INCREASING THE USE OF ALTERNATIVE FUELS AT CEMENT PLANTS: INTERNATIONAL BEST PRACTICE © 2017 International Finance Corporation All rights reserved. 2121 Pennsylvania Avenue, N.W. Washington, D.C. 20433 ifc.org The material in this work is copyrighted. Copying and/or transmitting portions or all of this work without permission may be a violation of applicable law. IFC does not guarantee the accuracy, reliability or completeness of the content included in this work, or for the conclusions or judgments described herein, and accepts no responsibility or liability for any omissions or errors (including, without limitation, typographical errors and technical errors) in the content whatsoever or for reliance thereon. Cover Image: Sofies AS TABLE OF CONTENTS ABBREVIATIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . vi ACKNOWLEDGMENTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . vii ABSTRACT  .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . vii FOREWORD . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . viii 1 OVERVIEW OF THE USE OF ALTERNATIVE FUELS IN THE CEMENT INDUSTRY . . . . . . . . . . . . . . . . . . . . . . 1 1.1  Worldwide Use of Alternative Fuels in the Cement Industry  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 1.2  Fuel Preparation  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 1.2.1  Hazardous Waste . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 1.2.2  Non-hazardous Industrial and Commercial Wastes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 1.2.3  Municipal Waste  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 1.2.4 Biomass . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 1.2.5  Other Unclassified Alternative Fuels  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 1.3  Review of Pretreatment Technologies .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 1.3.1  Mixing in Liquid Phase . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 1.3.2  Mechanical Treatment  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 1.3.3  Bio-mechanical Treatment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 1.3.4  Other Pretreatment Techniques  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21 2 COMPREHENSIVE INFORMATION BY ALTERNATIVE FUEL TYPE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24 2.1  Hazardous Spent Solvents  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24 2.2  Waste Oil and Industrial Oil . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25 2.3 Wastewater . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26 2.4  Used Tires and Rubber Waste . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27 2.5  Industrial Sludge . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28 2.6  Non-hazardous Industrial Waste . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29 2.7  Municipal Solid Waste . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31 2.8  Municipal Sewage Sludge . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32 2.9  Construction and Demolition Waste  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33 2.10  Biomass and Green Wastes  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34 2.11  Animal Meal .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35 Increasing the Use of Alternative Fuels at Cement Plants: International Best Practice i 3 KEY SUCCESS FACTORS FOR ALTERNATIVE FUEL PROJECTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37 3.1  Success Criteria for Alternative Fuel Projects  .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37 4 FOUR CASE STUDIES OF ALTERNATIVE FUEL USE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38 4.1  Municipal Solid Waste . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38 4.1.1  Composition of Municipal Solid Waste  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38 4.1.2  Quality of Refuse-derived Fuel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39 4.1.3  Preparation of Municipal Solid Waste . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39 4.1.4  Business Models . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42 4.1.5  Conditions for an Alternative Fuel Project Using Municipal Solid Waste  . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43 4.2  Sewage Sludge  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44 4.2.1  Description of Municipal Sewage Sludge . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44 4.2.2  Positioning of Cement Plants in the Municipal Sewage Sludge Segment  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44 4.2.3  Quality of Municipal Sewage Sludge . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45 4.2.4  Preparation of Municipal Sewage Sludge . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45 4.2.5  Business Models . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46 4.2.6  Extension to Industrial Sludge  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46 4.3 Biomass  .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47 4.3.1  Description of Biomass Waste  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47 4.3.2  Positioning of Cement Plants in Biomass Source Collection  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47 4.3.3  Quality of Biomass Alternative Fuels  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48 4.3.4  Preparation of Biomass Alternative Fuels .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49 4.3.5  Technical Considerations for Biomass Integration in the Cement Process . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49 4.3.6  Main Steps to Implement a Pilot Project Based on Biomass Sources .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49 4.4  Industrial Waste  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49 4.4.1  Non-hazardous Industrial Waste  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50 4.4.2  Blending of Hazardous Industrial Waste  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53 APPENDIX 1: DETAILED INFORMATION BY ALTERNATIVE FUEL TYPE  .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56 APPENDIX 2: USE OF ALTERNATIVE FUELS IN CEMENT PRODUCTION: THE CASE OF POLAND . . . . . . . . . 77 ii Increasing the Use of Alternative Fuels at Cement Plants: International Best Practice LIST OF TABLES Table 1:  Alternative Fuel Substitution Rates in Selected Countries and Regions  .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 Table 2:  Shares of Different Types of Waste Used as Alternative Fuels by Large International Cement Groups  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 Table 3:  Type of Municipal Sewage Plant Affects Quality . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45 Table 4:  Quality Characteristics of Selected Biomass . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49 Increasing the Use of Alternative Fuels at Cement Plants: International Best Practice iii LIST OF FIGURES Figure 1:  Breakdown of Alternative Fuels and Main Fuel Types in the EU-28  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 Figure 2:  Solvent Storage in Austria and Storage and Recirculation Pumps in the United States . . . . . . . . . . . . . . . . . . . . . 4 Figure 3:  Oil Lagoons in the United Arab Emirates  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 Figure 4:  Storage and Injection Facility for Solid Wastes in Mexico  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 Figure 5:  Jumbo Trucks Used in the Cement Industry in the Philippines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 Figure 6:  Storage of Rice Husks for Off-season Use . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 Figure 7:  Decommissioned Seeds .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 Figure 8:  Wood from Rubber Trees in Africa  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 Figure 9:  Reception and Storage of Animal Meal in France and Japan  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 Figure 10:  Wood Waste Sorting Table in New England and Grinding Unit in Singapore  . . . . . . . . . . . . . . . . . . . . . . . . . 12 Figure 11:  Examples of Manufactured Items Based on Used Tires  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 Figure 12:  Solvent Mixing in Storage Tanks in France  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 Figure 13:  Pretreatment in Liquid Phase in the United States  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 Figure 14:  Pretreatment Line in Spain, with Milling at the Top of the Process  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 Figure 15:  Physical-chemical Pretreatment Unit Scori at the Leuna Refinery in Germany  . . . . . . . . . . . . . . . . . . . . . . . . 16 Figure 16:  Schematic of the Fabrication Process, Mixing Tower in Belgium, and Closed-circuit Production Unit in Norway  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 Figure 17:  Example of Typical Solid Waste Before Pretreatment, in Austria  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 Figure 18:  Examples of a Primary Mill and Cutting Table  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 Figure 19:  Manual Sorting Table, Trammel, and Air Separator  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 Figure 20:  Secondary Shredding Mill in Austria and Mexico  .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 Figure 21:  Schematic Showing the Bio-mechanical Treatment Process on a Landfill Site  . . . . . . . . . . . . . . . . . . . . . . . . . 20 Figure 22:  Classical Bio-mechanical Treatment Unit  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21 iv Increasing the Use of Alternative Fuels at Cement Plants: International Best Practice Figure 23:  Schematic of the AK System Process . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21 Figure 24:  Schematic of the Biomass Drying Process and Moisture Content  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22 Figure 25:  Belt Dryer Using the Excess Exhaust Gases from Kilns  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23 Figure 26:  Sequence of Pretreatment of Oil Sludge  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23 Figure 27:  Schematic Definition of the Collection and Sorting Systems Leading to RDF Production . . . . . . . . . . . . . . . . . 39 Figure 28:  Schematic of the Sorting System for the Preparation of Municipal Solid Waste .. . . . . . . . . . . . . . . . . . . . . . . 40 Figure 29:  Schematic Showing the Preparation of Municipal Solid Waste with Thermal Dryer  . . . . . . . . . . . . . . . . . . . . 41 Figure 30:  Schematic of Biodrying Process for Municipal Solid Waste  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42 Figure 31:  Schematic of Drying Process for Municipal Sewage Sludge  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44 Figure 32:  Picture and Schematic of Sewage Sludge Processing Unit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46 Figure 33:  Map of the Coffee Husk Collection Network in Uganda . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48 Figure 34:  Schematic of the Distribution in the Collection and Treatment Modes in France in 2008 Before the Reduction of Landfilling  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50 Figure 35:  Potential Positioning of Co-processing in Management of the Non-hazardous Industrial Waste Stream  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51 Figure 36:  Schematic of RDF Production from Paper Waste to Cement Plant  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52 Figure 37:  Example of Flowsheet for Liquid Alternative Fuel Preparation  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54 Figure 38:  Example of Facilities for Liquid Alternative Fuel Preparation  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54 Figure 39:  Example of Flowsheet for Solid Alternative Fuel Preparation  .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55 Increasing the Use of Alternative Fuels at Cement Plants: International Best Practice v ABBREVIATIONS CAPEX Capital Expenditure MW Megawatt CDM Clean Development Mechanism MWh Megawatt hour COD Chemical Oxygen Demand NHIS National Health Information Survey CSI Cement Sustainability Initiative OPEX Operational Expenditure GTP Gross Technical Potential PCB Polychlorinated Biphenyl IFC International Finance Corporation RDF Refuse-derived Fuel (typical calorific value of Kt Kiloton 8–15 MJ per kilogram, moisture of 25–40% LCV Lower Calorific Value and particle size of 0–400mm) MBT Mechanical Biological Treatment SRF Solid Refuse Fuel (also known as Solid MJ Mega Joule Recovered Fuel, (typical calorific value of over MSS Municipal Sewage Sludge 15 MJ per kilogram, moisture of less than 15% MSW Municipal Solid Waste and particle size of 0–35mm) vi Increasing the Use of Alternative Fuels at Cement Plants: International Best Practice ACKNOWLEDGMENTS This report was produced in cooperation between IFC, SNIC (Sindicato Nacional da Indústria do Cimento), and ABCP (Associação Brasileira de Cimento Portland). Development of the report was managed by Alexander Sharabaroff (IFC), Gonzalo Visedo (SNIC), and Mauricio Pecchio (ABCP). The primary authors include Dominique Bernard, Daniel Lemarchand, Nicolas Tétreault, Charlotte Thévenet, and Amaury de Souancé of Sofies AS. Professor Dr. José Goldemberg and Professor Dr. Cristiane Cortez shared invaluable insights to the report. The team would like to acknowledge a tremendous contribution to this report by Michel Folliet (IFC), James D. Michelsen (IFC), José Otavio Carvalho (President, SNIC), Renato José Giusti (President, ABCP), Hugo da C. Rodrigues Filho (ABCP), and Antonia Jadranka Suto (ABCP); Araceli Fernandez Pales, Kira West, and Steffen Dockweiler of the International Energy Agency (IEA); and Alexios Pantelias, John Kellenberg, Jeremy Levin, Luis Alberto Salomon, Sivaram Krishnamoorthy, Dragan Obrenovic, Denis Obarcanin, Yana Gorbatenko, and Alexander Larionov of IFC. ABSTRACT This report, and an accompanying report on thermal and electric energy efficiency, provide a summary of international best practice experience in the cement sector and focus on specific technical measures that could be implemented by cement plants to reduce their operating costs and improve their carbon footprints. The reports provide a plethora of practical information from implemented projects and include detailed technical descriptions, estimates of capital and operating costs, as well as case studies and references from locations where the measures have been implemented. A combination of general and in-depth information will make these reports a helpful read to both management and technical and operating personnel of cement plants as well as to a larger range of stakeholders. Increasing the Use of Alternative Fuels at Cement Plants: International Best Practice vii FOREWORD Cement is paramount for economic development and poverty reduction in emerging markets. Along with aggregates and water, cement is the key ingredient in the production of concrete, and, as such, is an essential construction material that enables large infrastructure projects in energy, water, and transport, as well as, importantly, the construction of modern buildings and urban infrastructure. Given the rapid urbanization rates in developing countries, cement is crucial for delivering on the climate-smart cities agenda. Emerging markets have been rapidly increasing their cement use and now account for over 90 percent of cement consumption worldwide (4.1 billion tons in 2016). Cement accounts for at least 5 percent of anthropogenic emissions of greenhouse gases, and, according to some estimates, this share may be even higher. At the same time, energy-related expenses in the cement sector, mostly on fossil fuels and electricity, account for 30 to 40 percent of the industry’s cash costs. While current energy prices are still recovering from the global financial and economic crises, there is no doubt that they will continue to increase in the long run. In recent years, the cement industry has been successful in reducing its operating costs and improving its carbon footprint (emissions per unit of output) by improving energy efficiency, increasing the use of alternative fuels, and deploying renewable energy sources. With a cumulative investment portfolio in cement of over $4.2 billion, IFC has accumulated a vast experience in the industry, including in sustainable energy projects. To share its knowledge with external stakeholders and to promote sustainable practices in the sector, IFC commissioned two studies on international best practice, covering alternative fuels, and thermal and electric energy efficiency. These studies were developed as part of the Brazil Low Carbon Technology Roadmap led by the National Cement Industry Association of Brazil (SNIC), the Brazilian Association of Portland Cement (ABCP), the International Energy Agency (IEA), the Cement Sustainability Initiative (CSI) of the World Business Council for Sustainable Development (WBCSD), and IFC. This report, and an accompanying report on thermal and electric energy efficiency, provide a summary of international best practice experience in the cement sector and focus on specific technical measures that could be implemented by cement plants to reduce their operating costs and improve their carbon footprints. The reports provide a plethora of practical information from implemented projects and include detailed technical descriptions, estimates of capital and operating costs, as well as case studies and references from locations where the measures have been implemented. A combination of general and in-depth information will make these reports a helpful read to both management and technical and operating personnel of cement plants as well as to a larger range of stakeholders. Michel Folliet Milagros Rivas Saiz Chief Industry Specialist Manager Cement, Manufacturing, Agriculture and Services Cross Industry Advisory viii Increasing the Use of Alternative Fuels at Cement Plants: International Best Practice OVERVIEW OF THE USE OF ALTERNATIVE FUELS IN THE CEMENT INDUSTRY 1 This chapter provides an overview of the worldwide use Table 1 summarizes the alternative fuel substitution rate in of alternative fuels in the cement industry, followed by a the cement sectors of selected countries during the period review of the different categories of alternative fuels and of 2010–2012. Poland, in particular, has seen rapid evolution in pretreatment technologies. its substitution rate, with the share of alternative fuels in the country’s cement sector now at 45 percent, far exceeding the 1.1  WORLDWIDE USE OF ALTERNATIVE FUELS CSI guidelines. Factors behind this remarkable growth are IN THE CEMENT INDUSTRY elaborated in Box 1. The first major use of alternative fuels in the cement manufacturing industry emerged during the mid-1980s. The primary goal in substituting fossil fuels was to enable Table 1: Alternative Fuel Substitution Rates in Selected the industry to remain economically competitive, as fuel Countries and Regionsa consumption accounts for almost one-third of the cost of Substitution Rate (%) producing clinker. Any positive impact on the environment Country CSI Guidelines 2010–12 was considered an added benefit. Germany 42 65 Since then, there has been increasing sensitivity to the Belgium 30 60 environmental impact of human and industrial activities. Beyond the cost-cutting benefits of alternative fuels, use of Switzerland 47.8 52.8 these fuels can contribute greatly to the environmentally sound disposal of waste and to the mitigation of Poland 1 45 greenhouse-gas emissions (GHG). Therefore, key cement players started to consider alternative fuels as a lever to Sweden 29 45 improve their contribution to sustainable development and as a key component of corporate social responsibility. France 28 30 Alternative fuels are at the heart of the Cement Sustainability Initiative (CSI), in which the largest worldwide cement Spain 1.3 22.4 companies are actively involved under the umbrella of the World Business Council for Sustainable Development. United Kingdom 6 19.4 The growth in alternative fuel use in cement kilns has been Japan 10 15.5 fostered by the 17 members of the CSI, all of whom are large cement companies operating worldwide. In December Brazil (2014) no data 8.1 2005, the CSI issued guidelines for the selection and use of alternative fuels and alternative raw materials in the cement Source: Sofies AS.  zad Rahman et al., “Recent Development on the Uses of Alternative Fuels in a. A manufacturing process. The document also contained details Cement Manufacturing Process,” Fuel 145 (April 2015): 84–99, doi:10.1016/j. on alternative fuel use in different countries. fuel.2014.12.029. Increasing the Use of Alternative Fuels at Cement Plants: International Best Practice 1 Box 1: Use of Alternative Fuels in Cement Production: The Case of Poland Over the past decade, the cement sector in Poland has experienced rapid growth in its use of alternative fuel sources for industrial processing. As shown in Table 1, the alternative fuel substitution rate in Poland reached 45 percent in 2011. It has continued to increase in recent years and is now above 60 percent, with some cement plants using up to 85 percent alternative fuel. The expansion of co-processing in Poland was made possible as a result of: • Strong commitment of the cement sector, including through: grasping the alternative fuel market opportunities as they were emerging; establishing mid-term and/or long-term contracts with the waste management sector; smart and continuous investments in the handling (and in some cases preparation) of alternative fuels; and the development of skills in kiln operation to accept low-quality alternative fuels. • Ongoing enforcement of waste regulations, particularly those related to landfilling. • A favorable economic context comprising smart national and international investments, taxation on landfilling, and some alternative fuel opportunities supported by European subsidies. A more detailed overview of the experience with alternative fuels in Poland can be found in Appendix 2. 1.2 REVIEW OF ALTERNATIVE FUELS, MARKETS, Table 2 summarizes the shares of different types of waste AND ACTORS that are being used as alternative fuels by five leading Although a variety of technical constraints limit the use of international cement producer groups.1 alternative fuels in cement plants, the range of wastes that Below is an overview of the various types of alternative fuels potentially can be used in the cement sector is very broad. used in the cement industry, followed by a review of diverse In addition to any processing limitations, the cement sector pretreatment techniques. has developed international guidelines listing waste that is prohibited for use as alternative fuel, including radioactive 1.2.1 HAZARDOUS WASTE waste, infectious waste, and explosives. Cement plants in the United States and Europe began their The waste used by cement plants as alternative fuel can be use of alternative fuels with hazardous waste, which offers classified into five broad categories, which generally are specifications that are close to those of the fuel oil and coal associated with specific regulations and/or implementation that traditionally are used in cement manufacturing. constraints related to the materials: SPENT SOLVENTS • Municipal waste Spent solvents were the first category of waste to be targeted as alternative fuel by cement companies. Largely available • Biomass on the market in the late 1970s, spent solvents combine • Non-hazardous industrial and commercial waste three main advantages: high calorific value, a liquid phase • Other unclassified alternative fuels. facilitating their injection into the heating hood, and the ability for the cement to receive a disposal (gate) fee Both research and international experience suggest that no as a result of regulatory pressures on hazardous waste single alternative fuel can, by itself, meet the entire thermal management. There are a number of important factors to be demand of cement manufacturing. However, a mix of considered including but not limited to: the chlorine content, different alternative fuels can achieve that goal. compatibility mixtures (concern about setting off reactions), Figure 1 shows the breakdown of the alternative fuel supply in the European Union. Alternative fuels are dominated by 1 Azad Rahman, M. G. Rasul, M. M. K. Khan, and S. Sharma, plastics which account for 31.6 percent of the total fuel supply “Impact of Alternative Fuels on the Cement Manufacturing Plant Performance: An Overview,” Procedia Engineering 56 in the region, followed by tires and mixed industrial waste. (2013): 393–400, doi:10.1016/j.proeng.2013.03.138. 2 Overview of the Use of Alternative Fuels in the Cement Industry Figure 1: Breakdown of Alternative Fuels and Main Fuel Types in the EU-28 Breakdown of Alternative Fossil Fuels, EU28, by percent 3.4 2.1 Plastics 5.2 Mixed industrial waste 6.3 Tyres 6.5 37.1 Other fossil based wastes Other biomass 6.8 Animal bone meal, animal meal and animal fats (biomass) Solvents 14.9 Impregnated sawdust 17.7 Waste oil Breakdown of Main Fuel Types, EU28 63.7 31.6 4.6 Conventional fossil fuels Alternative fossil fuels Biomass Source: Cembureau, March 2015. and security constraints related to the handling of products automotive industry). Available quantities of spent solvents with a low flash point. have declined considerably over the years as a result of producers’ efforts to reduce solvent use at the source, to The main sources of spent solvents are the chemical develop regeneration, and to alter manufacturing processes and pharmaceutical industries and the manufacture (particularly for powdered and water-based paints). Spent and use of paints, glues, and varnishes (including in the solvents are still a significant alternative fuel in some cement Table 2: Shares of Different Types of Waste Used as Alternative Fuels by Large International Cement Groups Waste Type Used as Alternative Fuel Holcim Cemex Heidelberg Italcementi Lafarge Waste oil 5 3.7 8.5 22.1 Solvent and liquid waste 11 4.7 21.9 Tires 10 16 11.6 14.9 19.7 Impregnated sawdust 6 Plastic 9 26.4 4.7 33.1 Industrial and household waste (solid) 65 13.8 Industrial waste and other fossil-based fuel 30 Meat and bone meal 2 4 6.1 15.7 Agricultural waste 9 10 4.2 11.1 Wood chip and other biomass 15 5 24.5 25.1 Sewage sludge 2 4.1 1.7 Other alternative fuel 14.6 Source: Sofies AS. Increasing the Use of Alternative Fuels at Cement Plants: International Best Practice 3 plants in the United States and Europe (see Figure 2). Even The market for used solvents has stabilized in Western with low substitution rates, they have the advantage of Europe and North America. It still represents some 100,000 making it easier to use low-calorific fuels in the mix nozzle. to 200,000 tons per year in the Benelux countries, France, and the United Kingdom. This alternative fuel source also Finally, spent solvents are used to dilute pasty wastes (paint allows at least two cement plants in the United States to sludge, resins, glues, distillation bottoms, and distillation operate at nearly 100 percent substitution. columns) in pretreatment facilities and to facilitate the handling of a liquid mixture injection at the nozzle (see USED OIL Section 2.3). Because of its high calorific value and ease of handling and burning, used oil is a very attractive and valuable The market for spent solvents is competitive, with cement alternative fuel. The ability of cement plants to access this plants vying with hazardous waste incineration facilities waste segment at competitive prices depends entirely on the for the resource. The solvents are useful to incinerators regulatory environment. because they can supply the energy required to operate the incineration kilns, avoiding the need for additional fossil The illegal disposal of used oil, facilitated by a multitude of fuels. When the average calorific value of their waste mix is small users (such as garages and repair shops), contributed low, incineration companies have no problem moving into greatly to the eutrophication (excessive nutrient loading the spent solvents market segment at very competitive prices leading to oxygen depletion) of surface waters in Europe. compared to those of cement plants. The use of oil-burning stoves to heat factories also was a source of pollution because of incomplete combustion and Cement plants complement solvent recycling activities, as the emission of heavy metals. the spent solvents can be distributed to one use or the other depending on the quality of the solvent. Moreover, the In the mid-1980s, to prevent the unsafe disposal of used solvent recycling process generates distillation residues that oil, France set up a clear regulatory scheme with an efficient can be used as alternative fuel by the cement industry. financial incentive tool and tracking system, helping to Figure 2: Solvent Storage in Austria (left) and Storage and Recirculation Pumps in the United States (right) Source: Sofies AS. 4 Overview of the Use of Alternative Fuels in the Cement Industry greatly reduce illegal disposal. Because of the country’s developed countries where regulation prohibits the landfilling low recycling capacity, the cement industry has quickly of hazardous organic waste, specialized hazardous waste seized this waste segment, with annual consumption of incinerators compete directly with cement producers for the used oil peaking at 150,000 tons. The French government sludge resource. The production costs of the two sectors are has encouraged energy recovery in cement kilns, as a similar, making this competition relatively balanced. lifecycle assessment showed that the cement route had preferable outcomes to acid regeneration in all categories of In developing countries, low regulatory pressure fosters environmental impact. the landfilling or onsite storage of industrial sludge. In this market segment, manmade lagoons of aging oil sludge The European Union nevertheless has taken a dogmatic are often found. Oil sludge is used in well drilling and is approach in favoring material recovery over energy recovery. present in oil-refining countries, particularly in the Middle This has greatly reduced the amount of waste oil recovered East. Significant amounts of this sludge are recoverable in in the cement industry. Outside of Europe, the used oil dedicated lagoons (for example, 100,000 tons per year have market segment has been accessible only sporadically to the been recovered for use in cement plants in Romania in the cement industry (for example, in Chile). Pollution arising last five years). Deposits estimated at 12 million cubic meters from the illegal and unsafe disposal of used oil could bring in the Gulf countries and 5 million cubic meters in Nigeria change, but this would need to pass by a regulatory lever. could be valorized (see Figure 3). INDUSTRIAL SLUDGE POLLUTED (WOOD AND PLASTIC) PACKAGING The industrial sludge market segment has grown rapidly This category includes, for example, chemical packaging, in parallel with the decrease in the use of spent solvents, in oil packaging from garages, and fertilizer packaging. The part because of the source reduction efforts undertaken by market segment is relatively new and is growing both in waste producers (the byproduct of concentrating industrial developed countries with advanced regulation as well as waste is industrial sludge, for example). The use of concrete in countries with emerging regulation, where it represents pumps for injection has allowed for the direct use of sludge one of the first segments of solid waste that is banned in cement kilns; however, direct injection is limited by from landfilling. Polluted packaging waste is generated the need to maintain good combustion. Industrial sludge by industries of various sizes, as well as by the general therefore typically is either pretreated by diluting the liquid population. Selective collection and strict enforcement or dispersed using a powdery carrier. of regulation are the two key factors necessary to create this waste stream. For example, France alone produces an Industrial sludge and spent solvents have similar origins estimated 1 million tons per year of polluted packaging (for example, chemical, parachemical, petrochemical, waste. This is an affordable segment for the cement mechanical, paints, varnishes, resins, distillation residues). In industry, with prior shredding occurring given the potential Figure 3: Oil Lagoons in the United Arab Emirates Source: Sofies AS. Increasing the Use of Alternative Fuels at Cement Plants: International Best Practice 5 chemical hazards. As with many other wastes, the main SUMMARY competition is from specialized incinerators. In Brazil, the Overall, hazardous waste is an easily accessible market polluted packaging waste segment already exists, and several segment for the cement industry. The cement process offers pretreatment platforms are focused on it. specific environmental advantages, enabling it to be a AQUEOUS WASTE competitive solution compared to traditional hazardous waste disposal routes. In some countries, such as India, Although aqueous waste is not classifiable under the hazardous waste represents one of the only economically category of alternative fuel, the cement process can provide accessible segments because of the high concentration of an effective service for removing this type of waste. polluting industries in certain states (for example, chemical Moreover, the injection of water at the mixing nozzle lowers industries in Gujarat). the amount of thermal nitrogen oxides produced. However, the amount of hazardous waste generated is lower There are many types of aqueous waste, including cutting than that of non-hazardous waste (discussed later); thus, oils; wastewater from chemical reactions and reactor it generally does not ensure a very high level of fossil fuel cleaning in the chemical, pharmaceutical, and para-chemical substitution for the cement industry. Except in special cases, industries; and de-icing water from airports and roads. such as with some plants in the United States and Europe, Generally speaking, any type of wastewater that has a the average level of fuel substitution with hazardous waste high chemical oxygen demand (COD), which is difficult to rarely exceeds 10 to 15 percent. dispose of in a wastewater treatment plant, is of interest for the cement disposal route. An important note regarding the market for hazardous waste is that the evolution of its characteristics makes pretreatment This market segment exists only in countries where increasingly unavoidable. In the past, most of the material regulations on water pollution are strong and restrictive. flow occurred via direct delivery to the cement kiln. Today, France is probably the country where incineration, evapo- more than 80 percent of the flow pass is pretreated. This incineration, and co-incineration of aqueous waste in cement trend can be seen in all geographical areas, including plants have been most developed. The amount used by the developing countries. French cement industry reaches several hundred thousand tons per year. Because of gate fees, hazardous waste can be transported over long distances without questioning the economic POLLUTED SOIL feasibility of co-processing in cement factories. In the United Geographical sites and polluted soil constitute a specific States, waste transfers occur between states as far apart as waste market segment. Their remediation stems from Ohio and Kansas. In India, cement plants can receive waste regulatory requirements and is generally practiced in from 1,000 kilometers away. countries that have strict soil pollution regulation. However, remediation also can be practiced in the case of Finally, one must keep in mind that using hazardous waste rehabilitation of polluted sites, for example in connection in cement plants often requires going through long and with real estate development in or near big cities. complex administrative authorization procedures, sometimes with a low success rate. The mineral composition of polluted soil is mostly compatible with the raw material for cement kilns. The sector 1.2.2 NON-HAZARDOUS INDUSTRIAL AND COMMERCIAL WASTES therefore is well suited to the treatment of soils polluted with hydrocarbons. The injection is done at the foot of the Initially, non-hazardous industrial and commercial wastes preheating tower so as to ensure destruction of the organic did not receive particular attention from the cement industry, matter while combining the minerals with the feedstock. as the sector was more focused on hazardous waste. At that 6 Overview of the Use of Alternative Fuels in the Cement Industry time, the costs of landfilling were low and landfill capacities substitution of fossil fuels has grown rapidly to more than 60 were significant. In addition, mechanical pretreatment percent on average, with some plants exceeding 80 percent. technologies were still embryonic. Note that quantities are potentially important, given the large The shift came from two converging effects: capacities of cement kilns. The market is broad. The level of interest depends on the cost of alternative solutions, but the • Regulatory changes resulting in significant increases in evolution of pretreatment techniques has made the cement waste disposal costs, mainly in Europe as a result of the industry competitive, including in the United States (where ban on the landfilling of recyclable and organic waste; and landfill capacity is an important concern), where running costs • Willingness of the cement plants to reach a high are as low as $20 to $25 per ton outside the Northeast. substitution rate even with limited and decreasing Unlike for hazardous waste, where cement manufacturers amounts of hazardous waste. often are able to approach producers directly, the structure Demand for non-hazardous industrial and commercial of the industrial and commercial solid waste market is based wastes first emerged in Germany and Austria, thanks to primarily on a collection service. Cement manufacturers strict implementation by countries affected by the European have to deal with waste collection companies to guarantee directive limiting landfilling. Following implementation their supplies in a context of balance or imbalance in of the Landfill Directive, Germany faced a lack of waste supply and demand, which affects the relative power of the disposal solutions, given its limited incineration capacity. economic partners. To consolidate their positions, the major Consequently, the manufacturing of shredded solid fuel cement companies often integrate pretreatment in their offer. developed naturally, spurring advances in sorting and This vertical integration sometimes is achieved through pretreatment techniques. partnerships between a collector and a cement producer. 1.2.3 MUNICIPAL WASTE Cement manufacturers themselves have made advances in their ability to use shredded solid waste. Use of this waste Municipal waste covers two major types of waste: municipal has developed steadily in Europe (Austria, the Benelux solid waste and municipal sewage sludge. countries, the Czech Republic, France, Italy, Poland, Spain, MUNICIPAL SOLID WASTE and the United Kingdom) and is now progressing worldwide (see Figure 4). In the German cement industry, the rate of Because of its heterogeneity, physical state, odor, and low calorific value, municipal solid waste is not, as such, Figure 4: Storage and Injection Facility for Solid Wastes in Mexico Source: Sofies AS. Increasing the Use of Alternative Fuels at Cement Plants: International Best Practice 7 ready for direct delivery to cement plants. It also can MUNICIPAL SEWAGE SLUDGE be prohibited from use for co-processing under certain Production of municipal sewage sludge has increased greatly guidelines. However, for the same reasons as for industrial with the development of communal sanitation. The land waste (landfill space limitations combined with difficulties area for spreading this sludge is becoming more and more in opening incinerators), the opportunity to produce an restrictive, and some disposal channels are increasingly alternative fuel derived from municipal solid waste has regulated (such as ocean dumping and landfilling). The use emerged in recent years. of sewage sludge as fuel, however, offers great interest. The production of RDF (refuse-derived fuel) from Sewage sludge can be injected directly into the back of the municipal solid waste involves two main aspects: sorting cement kiln, after a single pass on a filter press. However, its and shredding. The main producers of shredders developed calorific value is too low to make it a substitute fuel. In this dedicated machines mainly in Central Europe. Mechanical case, cement plants function instead as a disposal service. sorting has been established in parallel based on the density and/or size of the material. Sorting by material type has been The sludge also can be dried, giving it the characteristics much more complex, but efficient solutions now exist for the of a mid-calorific value alternative fuel, especially if it has removal of chlorine, iron, and non-iron metals. A particular not undergone digestion. This market, however, is totally attention should be paid to moisture management. Various dependent on the local context. The co-processing of sewage drying technologies are used in the industry: thermal or sludge competes with use of the sludge in incineration and biological. Integrated solutions are being proposed under the with its burning in power plants. name mechanical biological treatment (MBT) that include the technologies described above. Use of municipal sewage sludge in cement plants already exists in several countries, such as China, France, Japan, Spain, and RDF production is well developed in Central Europe and the United Kingdom. There are a few cases of drying in cement Italy as well as in the United Kingdom, but with some plants using waste heat from the cement kilns. differences in recovery routes. In Germany and Austria, the produced RDF is used locally in cement plants and power 1.2.4 BIOMASS plants; in Italy and Great Britain, the output is primarily AGRICULTURAL AND AGRO-INDUSTRIAL WASTES exported because of a lack of usage capacity. The best-known agricultural and agro-industrial waste for use in the cement industry is rice husk. In addition to its high Cement plants can enter into a contract either directly with calorific value, it contains a significant proportion of highly local authorities or with private companies that own and reactive silica, which combines very easily with some raw operate pretreatment facilities. As is the case for industrial mix. The use of rice husk in cement production has been waste, cement plants may have the opportunity to vertically developed in most rice-producing countries. The involvement integrate by taking part in the RDF preparation step. of some cement manufacturers in professionalization of the Technically, municipal solid waste markets can be supply logistics enabled them to capture significant market accessed by cement plants for RDF worldwide. However, share. In the Philippines, for example, Lafarge has achieved in an emerging market context, considering the waste substitution rates of more than 30 percent using only rice characteristics, low or no gate fee and limited regulations husk (see Figure 5). and enforcement, simpler technologies or more selective or Other forms of agricultural biomass waste include coffee labor intensive processes must be considered to produce husk, oil palm husk, cashew nut husk, and sunflower husk. RDF that is both technically and economically acceptable for Because the markets for these feedstocks are seasonal, their use by cement kilns, while taking into consideration the low use often follows the rhythm of the seasons; however, it also calorific value of the waste. 8 Overview of the Use of Alternative Fuels in the Cement Industry Figure 5: Jumbo Trucks Used in the Cement Industry in the Philippines Source: Sofies AS. can be spread throughout the year if stocks are substantial of this material. In India, for example, the government (see Figure 6). supports the use of husks for electricity generation in coal power plants. These wastes have received attention from international organizations. As part of its Resource Efficiency and Cement plants can use other agricultural and agro-industrial Cleaner Production program, the United Nations Industrial wastes as well. For example, significant amounts of waste Development Organization (UNIDO) has launched a from the cotton ginning and rice straw industries are major study on the development of biomass waste from the often left in the fields, either to decompose or be burned. production of rice and coffee in Asia and South America. This burning leads to air pollution, producing the high The program especially addresses energy recovery of waste concentrations of smog found in places such as Cairo, Egypt. in cement plants. 2 Although the quantities of these feedstocks are significant, their use in cement plants is limited because of their high In the agricultural and agro-industrial waste market segment, phosphorus content. cement producers usually compete with diffuse valorizations Cement producers have positioned themselves in niche 2 United Nations Environment Programme, “UNEP-UNIDO markets for this waste segment. For example, some have joint RECP Programme,” http://www.unep.org/ resourceefficiency/Business/CleanerSaferProduction/ used decommissioned seeds that have been treated with ResourceEfficientCleanerProduction/UNEP- pesticides, a source that cannot be overlooked (see Figure 7). UNIDOjointRECPProgramme/tabid/78757/Default.aspx. Figure 6: Storage of Rice Husks for Off-season Use Source: Sofies AS. Increasing the Use of Alternative Fuels at Cement Plants: International Best Practice 9 Figure 7: Decommissioned Seeds Source: Sofies AS. Additionally, genetically modified corn cobs have been GREEN WASTES offered to cement producers in Chile. Such residues represent Cement manufacturers have launched projects to exploit the tens of thousands of tons per year of byproducts with a byproducts of forest management. This includes, for example, high calorific value. The list of agricultural waste from the wood from the management and replacement of rubber trees food industry is long, and it depends on the local context. in Africa (see Figure 8). Large tree plantations represent a In general, however, this waste is more accessible for the significant source of untapped fuel. In such cases, the cement cement sector in developing countries. manufacturer traditionally has contracted directly with the owner of the plantation and outsourced operations. Finally, biomass fuel can be found in many agro-industries— for example, chicken litter from poultry farming or dried Freshly cut wood has a low heating value. To be properly sludge from the production of beer. valorized, it must be subjected to natural drying or forced drying after being ground up. The economic feasibility of Figure 8: Wood from Rubber Trees in Africa Source: Sofies AS. 10 Overview of the Use of Alternative Fuels in the Cement Industry the latter option could be improved by using the waste heat well as Japan, also were concerned about mad cow disease. from cement kilns for drying operations. Thus, public incentives have contributed to accelerated development of this sector. Although the quantities of animal The market for wood chips and pellets also is significant. For meal have decreased sharply in recent years, the facilities example, several million tons of this feedstock is produced in cement plants continue to operate using other waste, in Canada and the United States each year. The decline including powdery waste such as sawdust and coal dust. in production of wood pulp in these countries has led manufacturers to switch their activities to wood energy, much PLASTIC AND WOOD WASTE FROM THE CONSTRUCTION AND DEMOLITION SECTORS of which is exported to Europe. Generally, these fuels are marketed at rates that remain unattractive for cement plants. In some countries, particularly in North America, large quantities of wood materials are used in construction, 1.2.5 OTHER UNCLASSIFIED ALTERNATIVE FUELS resulting in significant construction and demolition waste. ANIMAL MEAL Projects aimed at recovering this waste and turning it into Because of concerns about mad cow disease, markets in a fuel for cement plants have been developed in Richmond many countries have stopped using meal from livestock (Vancouver) and St-Constant (Montreal) in Canada, as well quartering in animal feed. The need to find a rapid solution in Singapore (see Figure 10). for disposing of these flours pushed cement producers to Because of its large volume, construction and demolition respond by developing equipment for receiving and storing waste is receiving growing attention. Extraction of its fuel this material and injecting it into their kilns (see Figure 9). fraction may have to grow in industrialized countries. The In France, the quantities of animal meal processed peaked Netherlands has been a pioneer in this area. In Japan, the at 350,000 tons per year. Many European countries, as Figure 9: Reception and Storage of Animal Meal in France (left) and Japan (right) Source: Sofies AS. Increasing the Use of Alternative Fuels at Cement Plants: International Best Practice 11 Figure 10: Wood Waste Sorting Table in New England (left) and Grinding Unit in Singapore (right) Source: Sofies AS. lack of landfill capacity also has led to the recovery of such is a source of secondary waste, such as steel tire cords or waste in the country. granules without economical value. USED TIRES AND RUBBER WASTE Attempts to convert tires into a more convenient fuel Used tires are often cited as the best example of an source, for example by using pyrolysis, have not yielded alternative fuel for use in the cement industry. This waste is expected results. by definition homogeneous, although the calorific value is In Europe, introduction of the principle of extended producer impacted by the level of wear, and iron from the tire frames responsibility has facilitated the development of this market. enters easily into the chemical composition of the raw mix. In France, for example, Aliapur, owned by the country’s major Kiln temperatures ensure complete combustion. Whole tires tire manufacturers, manages the bulk of used tire disposals. In from light vehicles and small vans can be introduced via a general, the supply chains of used tires for cement plants are double-flap system, requiring only a low level of investment. based on direct agreements with manufacturers. Although the cement process is highly suitable for energy However, used tires often find a second or third life in many recovery from used tires, the market realities differ by country. emerging countries, with parallel material recovery routes. In industrialized countries, uncontrolled disposal of tires is The production of shoe soles is probably the most well- less accepted by the general population (because of the visible known valorization of used tires, but it is not the only one impact on the landscape). Furthermore, accidental fires at (see Figure 11). used tire storage facilities have attracted attention because of the difficulties of controlling the blazes (for example, at St. These parallel recovery routes enable valorization of used Amable tire depot in Canada). Finally, water that stagnates in tires that makes them inaccessible to cement producers, as is the envelopes of tires promotes the breeding of mosquitoes, the case in India and China. bringing associated risks of dengue fever and malaria. 1.3 REVIEW OF PRETREATMENT TECHNOLOGIES Today, around 50 percent of the available used tire resource worldwide is recovered. This material recovery can take Various pretreatment technologies are available to the very different forms, from the production of granules to cement industry today. Their purpose is to homogenize a the stabilization of road banks. The production of granules range of alternative fuels into a form that can be introduced 12 Overview of the Use of Alternative Fuels in the Cement Industry Figure 11: Examples of Manufactured Items Based on Used Tires Source: Sofies AS. more easily into the kiln, while removing undesirable recirculation in the storage tanks on-site at the cement plant components and/or increasing the calorific value of the fuel. (see Figure 12). 1.3.1 MIXING IN LIQUID PHASE More recently, the decline in the amounts of spent solvents MIXING WITH SOLVENTS available, along with the advent of high-viscosity muddy and/ or pasty wastes, including the frequent conditioning of pasty Historically, mixing with solvents was the first pretreatment waste in barrels, has led to increased sophistication in liquid- technique developed for alternative fuels. This approach was phase mixing techniques. These techniques generally are applied to solvents in the mid-1980s. Originally, the high based on a pre-mixture of pasty waste with a small amount of availability of spent solvents with negligible impurities meant solvents by means of a stirrer at greater or lesser speed. The that only simple pretreatment techniques were necessary. result of this pre-mixture is then diluted via recirculation and In some cases, this involved merely mixing the solvent via agitation in large storage tanks (see Figure 13). Figure 12: Solvent Mixing in Storage Tanks in France Source: Sofies AS. Increasing the Use of Alternative Fuels at Cement Plants: International Best Practice 13 Figure 13: Pretreatment in Liquid Phase in the United States Source: Sofies AS. The most advanced variant includes first a milling process for which is akin to the emulsification of “oil in water,” was treating full barrels, with separation of the metal component developed in France from the know-how and technology prior to the mixing phase (see Figure 14). acquired from the rheology of cement pastes in wet kilns. In brief, the solids and hydrocarbons are diluted in water in the Techniques that use fast mixers allow for the injection of presence of surfactant adjuvants. The respective percentages fuels that have pasty-solid contents of up to 70 percent of water, solids, and oil are identical. The resulting fuel does through injection nozzles. These approaches are well suited not have a high calorific value, but its homogeneity, stability, to the scarcity of liquid waste. and ease of use make it attractive. EMULSIONS However, it is unlikely that use of this technology will A more suitable pretreatment technique exists for develop further given the limited market, as the process hydrocarbons that have high flash points. This technique, control today is concentrated on a single operator. 14 Overview of the Use of Alternative Fuels in the Cement Industry Figure 14: Pretreatment Line in Spain, with Milling at the Top of the Process Source: Sofies AS. PHASE SEPARATION reagents are added to facilitate the final step of separation by simple or forced sedimentation (centrifugation). Early pretreatment technologies were based on the principle of manufacturing homogeneous mixtures from liquid, solid, These technologies produce a high-quality fuel that can and pasty wastes. Phase separation, however, involves substitute the heating or ignition fuel. Their disadvantage is that the opposite approach, whereby the unwanted waste they generate solid waste for disposal and waste to be treated. components of more or less liquid heterogeneous waste are extracted, leaving only the most useful fuel phase. DISPERSION ON A POWDERY CARRIER The reduction in the quantity of liquid waste that was This approach applies primarily to waste oil that contains available and usable for producing alternative fuel that could water and sediment (for example, oil waste, cleaning waste be pumped and injected through injection nozzles led to the bins, emulsion cutting fluids). development of technologies based on the dispersion of pasty Phase separation is carried out using physical-chemical waste on a powdery carrier (generally made of sawdust). treatment techniques (see Figure 15). The raw waste is subject The process was first used in Belgium from pre-impregnated to filtration and a first separation of the static phase, and waste in Germany. At the time, the control of waste Increasing the Use of Alternative Fuels at Cement Plants: International Best Practice 15 Figure 15: Physical-chemical Pretreatment Unit Scori at the Leuna Refinery in Germany Source: Sofies AS. flows was not very strict, and the industry could be seen, Some facilities are operated in a completely closed circuit probably rightly, as a means of circumventing regulations on (see Figure 16). hazardous waste. Now, the main challenge is linked to the choice of The first installations of this type were very rustic and used adsorbent. In many countries, sawdust, which was the first simple wheel loaders for the blending. Few precautions were and main adsorbent, is becoming too expensive because taken to control the dust and volatile organic compounds of the development of biomass incineration. Many other produced during preparation of the fuel. However, these adsorbents have been tested, with only a few providing the questionable practices do not undermine the real attraction same efficiency as sawdust (for example, some foams sourced of pasty waste dispersion on a powdery carrier. Far from from plastic wastes or some variety of cellulose). This new being marginalized or rejected, this technology was further economic burden is linked to a decline in the number and developed by serious operators who have tackled and scope of applications of this technology. resolved the associated health and environmental issues. Today, the technology is well controlled and is recognized as a good practice in the Best Available Techniques Reference Document (BREF) for waste treatment published in 2006 by INERIS under the European Industrial Emissions Directive. The process is based on a sequence of mixing and screening phases. Most of the more advanced facilities have a head crusher for primary treatment of solids or barrels (as in the case of liquid mixtures discussed previously) and a secondary crusher for refining the finished product. Volatile organic compounds are collected and processed, as well as dust. 16 Overview of the Use of Alternative Fuels in the Cement Industry Figure 16: Schematic of the Fabrication Process (top), Mixing Tower in Belgium (bottom left), and Closed-circuit Production Unit in Norway (bottom right) Source: Sofies AS. 1.3.2 MECHANICAL TREATMENT The first of these mechanical treatment RDF platforms is for the organic fraction of non-biodegradable solid waste. The pretreatment methods presented so far have focused on This includes industrial waste (packaging and manufacturing the preparation of alternative fuels from hazardous waste. waste), construction and demolition waste, commercial Mechanical treatment methods are most commonly applied waste, and the dry fraction of municipal waste after to municipal, commercial, non-hazardous industrial waste collection and sorting and from landfills (see Figure 17). streams to make an RDF. Increasing the Use of Alternative Fuels at Cement Plants: International Best Practice 17 Figure 17: Example of Typical Solid Waste Before Pretreatment, in Austria Source: Sofies AS. The aim of mechanical treatment is to transform the waste into the operation is increased by the heterogeneity of the waste RDF, reducing it to a particle size that enables its introduction materials and the specifications of the RDF required by the in a cement kiln and to remove unwanted components that may cement kiln. Shredder maintenance (and the sequencing of be subject to higher-value materials recovery. the maintenance) is also key to reaching high-level efficiency. The protection of shredders using prescreening improves the Injecting the RDF into the top kiln requires a relatively fine efficiency of the shredding line and reduces maintenance costs particle size, whereas introducing it to the rear oven may by removing large pieces and metallic parts that are present in necessitate only a primary crushing. The sophistication of the the waste streams and cannot be shredded. applied technology therefore depends on the specifications of the finished product. A typical pretreatment line comprises: Shredding technology has progressed steadily during the last 15 • Coarse sorting using an industrial excavator in the years. How each particular type of waste responds to shredding receiving and storage area for the raw waste depends on the nature of the material. The complexity of • Primary grinding in a slow grinding mill (see Figure 18) 18 Overview of the Use of Alternative Fuels in the Cement Industry Figure 18: Examples of a Primary Mill and Cutting Table Source: Sofies AS. • First removal of ferrous metals using an over-band • Lastly, high-speed secondary shredding to adjust the magnet conveyer desired final particle size (see Figure 20). • Sorting of fractions from primary crushing, either manually Mechanical pretreatment chains are increasingly well or in a fully mechanized fashion (vibrating or star, trammel, mastered, and this industry is well organized and has broad ballistic, or ventilation sorting) (see Figure 19) experience. Most machine suppliers are proposing adapted • Second removal of ferrous metals to protect the shredders or integrated lines. However, an integrated line secondary crusher, and eventual extraction of nonferrous proposed by one supplier might not always be the most metals by eddy current efficient solution for a given waste stream. Figure 19: Manual Sorting Table, Trammel, and Air Separator Source: Sofies AS. Figure 20: Secondary Shredding Mill in Austria (left) and Mexico (center and right) Source: Sofies AS. Increasing the Use of Alternative Fuels at Cement Plants: International Best Practice 19 1.3.3 BIO-MECHANICAL TREATMENT yet benefit from an extensive list of industrial references. Nevertheless, one can cite a simplified variant of this Purely mechanical treatment may not be most appropriate approach to achieve accelerated anaerobic digestion in small- for waste streams that contains a biodegradable fraction, scale digesters on landfill sites, to later extract the solid fuel as is found in municipal solid waste (unless biodegradable fraction (known as the Ikos Environment process). fraction is removed first). For this type of waste, mechanical treatment could be accompanied by biological treatment Bio-mechanical treatment units can be implemented that uses bacteria to degrade the organic matter and dry the independently, although they also can be coupled with a alternative fuel. landfill to benefit from synergies, as shown in Figure 21. With the addition of biological technology to the mechanical Bio-mechanical treatment is a popular option with treatment RDF platform described in the previous section, surrounding communities due mainly to the combined effect the MSW, including the biodegradable fraction, are treated of regulatory pressure to close landfills and to the reluctance so that they are suitable as RDF. these technologies, the of populations to embrace incinerators. Accelerated growth production of This biological technology, generally is based of the bio-mechanical option is observed in some European on an aerobic degradation process that does not produce countries (for example, the United Kingdom). However, methane. The heat generated during the degradation process these technologies are still expensive, requiring a significant reduces the moisture content of the waste, and increases the civil engineering effort and the effective treatment of odors calorific value. However, there are technologies that combine (see Figure 22). Investments of €15 million to €20 million are anaerobic degradation to recover methane, followed by a typically necessary for an installation of 100,000 tons per bio-drying step. These are not widespread, and they do not year and a price of €26 per ton. Figure 21: Schematic Showing the Bio-mechanical Treatment Process on a Landfill Site Source: Sofies AS. 20 Overview of the Use of Alternative Fuels in the Cement Industry developed by the German company Convaero3—accelerated Figure 22: Classical Bio-mechanical Treatment Unit drying in a breathable textile membrane—appears to be an interesting compromise. In another example, the Japanese cement company Taiheiyo has transformed one of its kilns into a bio-digester to prepare an alternative fuel for kiln operation (known as the AK System process; see Figure 23), as part of a contract with the community of Hidaka. The project focuses on a relatively small quantity of 15,000 tons per year; however, it generated some €3.3 million in economic gain for the cement plant, although this also included the high royalties (€300 per ton) paid by the municipality. Source: Sofies AS. 1.3.4 OTHER PRETREATMENT TECHNIQUES Bio-drying techniques derived from composting practices The pretreatment technologies presented up to now are offer an interesting alternative. Investment costs are relatively widespread. They are fairly flexible and cover minimal, but this approach may require long periods of a wide scope of applications. This section describes a biodegradation and high land use. An intermediate solution 3 Purchased by Eggersmann. Figure 23: Schematic of the AK System Process Source: Taihiyo. Increasing the Use of Alternative Fuels at Cement Plants: International Best Practice 21 variety of other technologies that are adapted for specific With that said, at least one successful implementation has applications and thus are less commonly applied. been conducted in a cement plant for the pretreatment of waste for raw biomass with excessively high hydrocarbon TORREFACTION content. The application of pyrolysis for the cement industry Although less common, this technique is gaining in should remain very anecdotal. Even then, pyrolysis likely popularity worldwide. Torrefaction of biomass (for example, will remain a low-value option for the industry. wood or grain) is a mild form of pyrolysis at temperatures DRYING typically between 200 and 320 degrees Celsius. Torrefaction changes biomass properties to provide a much better fuel Some wastes, such as sewage sludge biomass, and the quality for combustion and gasification applications. Thus, biodegradable fraction of developing nations’ MSW, have this pretreatment increases the calorific value and ease of a moisture content that is high enough to negatively affect grinding for an injection nozzle. An interesting example of their calorific value. Drying techniques such as thermal, implementation for the cement industry is that of the group waste heat, and solar therefore greatly increases their Solvay, which has launched production at the industrial level potential use as alternative fuels. in the United States as part of a joint venture with the U.S. company New Biomass Energy. Drying can be natural or forced with different temperature levels. Figure 24 shows the drying time and the residual PYROLYSIS moisture content for biomass based on the techniques used. Pyrolysis does not in itself present a strong option for the The possibility of recycling free energy in the form of the cement industry, which normally is capable of using the hot exhaust gas that leaves cement kilns is not new. Already, energy content of waste without having to go through any this method is used extensively to produce electricity to treatment for gasification and/or production of heavy oil. run the process, especially in cement plants in China. Belt In addition, pyrolysis, which is a traditional and proven dryers are well suited to the relatively low temperatures of method, presents multiple implementation challenges related the exhaust gases (see Figure 25). In the last three years, this primarily to control of the load and quality of secondary technology has been implemented in cement plants to dry products generated by the reaction. RDF produced from municipal solid waste, for example. The moderate investment coupled with low operating costs and Figure 24: Schematic of the Biomass Drying Process and Moisture Content Source: Sofies AS. 22 Overview of the Use of Alternative Fuels in the Cement Industry Figure 25: Belt Dryer Using the Excess Exhaust Gases from Kilns Source: Sofies AS. the straightforward adjustment of moisture levels for specific approach is particularly suited to the homogenization of punctual needs are strong advantages. Producers of dryers pasty waste. For example, the technique has been developed for agricultural products are now diversifying their machines in the United Arab Emirates for the pretreatment of waste oil for use in waste treatment (for example, Stela of Germany). contaminated with sand (see Figure 26). INLINE MIXING Lastly, it is worth mentioning the inline mixing technique, which relies on the use of static mixers and inline mills. This Figure 26: Sequence of Pretreatment of Oil Sludge Source: Sofies AS. Increasing the Use of Alternative Fuels at Cement Plants: International Best Practice 23 2 COMPREHENSIVE INFORMATION BY ALTERNATIVE FUEL TYPE 2.1 HAZARDOUS SPENT SOLVENTS Hazardous Spent Solvents • The spent solvents segment is of interest for the Origin clinkerization process, given that the physico-chemical • Chemical and pharmaceutical industries characteristics of these solvents are close to those of • Painting and production of building materials • Cleaning activities in metals workshops or garages liquid fossil fuel. However, the available quantities must • Recycling activities be significant to compensate for the investment costs Composition required to manage the health and safety risks. Because handling of the solvents requires special competencies • Chlorine: 0% to 2%, average 0.6% to 1% • Moisture: 0% to 25% that frequently are not available in a traditional cement • Metal: 1,000 to 5,000 parts per million (ppm) plant, a dedicated skilled team is often called upon. • LCV: 20 to 28 gigajoules per ton • A cement plant can achieve 100 percent substitution Traditional Disposal/Usage Practices with spent solvents. • Thermal recovery in specialized incinerators or in cement plants (major) • For a kiln producing 500,000 tons per year of cement, • Recycling in an internal workshop or in specialized activities a 20 percent thermal substitution rate means between Supply Chains 5,000 and 15,000 tons of spent solvents per year, with • Collection and transport in adapted tanks (specialized a calorific value of about 20 gigajoules per ton. companies) or in drums for small and medium-sized production • The availability of spent solvents is decreasing as the • Nature of solvent and risk information clearly mentioned industry has started to successfully replace solvents Preprocessing and Utilization Technologies with water. • Transfer from drums • Blending • The gate fee/cost of spent solvents is directly linked to • Phase separation the fuel cost. In the case of a high fuel cost, the spent • Homogenization solvents must be bought by the cement plant and Main risks: chemical reaction, creation of a solid phase, mixing of recycling becomes a more profitable alternative, reducing chlorinated with non-chlorinated solvents available quantities. With a low fuel cost, a gate fee Risk Identification: Environmental Implications and Operational Health and Safety Considerations could be expected. • Compliance with environmental regulation • Appropriate and safe storage: steel that is compatible with solvent specifications, fire protection system • Handling within confined equipment or workshops with collection of volatile organic compounds • Use of personal protective equipment 24 Comprehensive Information by Alternative Fuel Type also is a key factor and could be subsidized via an Typical Technical, Policy, and Financial Barriers eco-tax on new oil. Technical barriers: • Chlorine quantity due to traditional chlorinated solvents • Recycling of used oil is developing and can absorb • Wide range of flash points possible the entire production of a country in a limited number • Risk of phase separation in storage with huge calorific value of facilities. variation Other barriers: • The potential of development for cement plants is • Availability of large quantities of spent solvents decreasing rapidly as recycling offers sufficient capacity. • Complex permit procedure for hazardous wastes with possible opposition from the population Waste Oil and Industrial Oil • Priority given to recycling Origin • Competition with specific incinerators • Any engine requiring lubrication (truck, car, power generator, etc.) Recommended Policy Actions • Industrial processes (steel production, tire manufacturing, food • Ban on disposal in the natural environment oil production, etc.) • Financial support (tax exemption, subsidies to investment, etc.) Composition CAPEX and OPEX • Chlorine: 0% to 1% (due to potential presence of cleaning • Unloading zone for trucks on concrete with collection of spillage solvents) • Stirred tanks in retention basins • Moisture: 0% to 20% (linked to storage conditions) • Pumping system for unloading, stirring, and injection • Metal: < 1,000 ppm • Filtration by auto-cleaning system or a static system in the • Pollution risks: PCB and solvents with low flash point unloading line • LCV: 25 to 35 gigajoules per ton • Electrical devices must be designed with consideration of the Traditional Disposal/Usage Practices flash point of the solvents (ATEX rules) • Recycling: limited by the cost of recycling (profitability CAPEX: €5 to €10 million threshold: oil waste production > 100,000 tons per year) OPEX: €10 to €20 per ton • Incineration with energy recovery (mainly in cement plants) Carbon Dioxide Mitigation Potential Supply Chains Biomass concentration = 0% • Collection from garages: need for frequent collection because of Full replacement of fossil fuels limited tank storage • Transit via central platforms before being sent to final destinations Preprocessing and Utilization Technologies 2.2 WASTE OIL AND INDUSTRIAL OIL Occurring at transit platforms: • The used oil segment is of interest for the clinkerization • Emptying of drums process, given that the physico-chemical characteristics • Blending of different oil wastes • Extraction of water via decantation (natural or accelerated by of the oil are close to those of liquid fossil fuel. Provided surfactant chemicals) that the investment needs for storage and handling are • Control of PCB pollution (small tanks to avoid pollution low, use could be profitable even for small quantities. diffusion) Risk Identification: Environmental Implications and • A cement plant can achieve 100 percent substitution with Operational Health and Safety Considerations used oil. For a kiln producing 500,000 tons per year, • Equipment and regulations have to be compliant with a 15 percent thermal substitution rate means between regulation related to hydrocarbon management 5,000 and 15,000 tons of waste oil per year, with a • Leakage prevention: tanks located in retention basins, pumping calorific value of about 25 gigajoules per ton. system locations that facilitate leakage collection (usually retention bin or concrete soil with drainage) • Mobilization of the resource is a key issue given the • Fire protection: adapted to hydrocarbon storage geographical dispersion of sources. The cost of collection • Protections adapted to solvents with low flash points Increasing the Use of Alternative Fuels at Cement Plants: International Best Practice 25 Typical Technical, Policy, and Financial Barriers Wastewater Technical barriers: Origin • Chlorine and PCBs because of oil coming from electrical Liquid wastes from economic activities such as: equipment (transformers or condensers) • Chemical and pharmaceutical processes • Homogeneity: risk of water separation in storage • Metals workshops Financial barriers: • Airport (de-icing) and road activities • Cost of collection: need for a free and reliable collection system • Industrial cleaning activities Policy barriers: Composition • Distortion of competition: recycling (artificial market • Chlorine: < 0.5% competition) and energy recovery (not the same environmental rules) • Moisture: > 80% • Complex permit procedure for hazardous wastes with possible • Metal: 1,000 to 2,000 ppm opposition from the population • Pollution risks: chemicals, surfactants, solvents, or oil. Recommended Policy Actions • LCV: 0 gigajoules per ton Implementation of a regulation that: Traditional Disposal/Usage Practices • Bans the discharge of used oil in sewers (1 liter of oil • Sewage plants (biological treatment) contaminates 1 milliliter of water) • Physico-chemical treatment • Bans illegal burning of used oil • Incineration Homogenization of regulations for different energy recovery Supply Chains processes Wastewater that is registered as hazardous waste (flammable CAPEX and OPEX or containing hazardous components) requires transport by • Unloading zone for trucks on concrete with collection of spillage specialized companies • Tanks in retention basin (former tanks for fuel oil in cement Preprocessing and Utilization Technologies plant can be reused) • Blending • Pumping system for unloading, stirring, and injection • Phase separation • Filtration by auto-cleaning system or a static system on the • Homogenization unloading line Main risks: chemical reaction, solidification, mixing of chlorinated • Electrical devices solvents with non-chlorinated ones CAPEX: €1 million to €3 million Risk Identification: Environmental Implications and OPEX: €5 to €10 per ton Operational Health and Safety Considerations Carbon Dioxide Mitigation Potential Equipment and regulations have to be compliant with regulation Biomass concentration = 0% related to solvent management. Full replacement of fossil fuels Delivery: • Handling of drums: volatile organic compound treatment system for buildings and personal protective equipment adapted for workers 2.3 WASTEWATER Storage: • The wastewater segment is of interest for cement plants, • Steel storage tanks adapted for alkaline or acidic components but in limited quantities and as a local service for industries. • Fire protection systems • Pumping system locations that facilitate leakage collection • An injection rate of about 1 to 2 tons per hour is achievable with a small capital expenditure, but quality control must be established. • The technical benefit is limited to a decrease in nitrogen oxide emissions. This means that the cement plant is offering a service that must be compensated at the right price. 26 Comprehensive Information by Alternative Fuel Type • The solution could be put into operation quickly; thus, Typical Technical, Policy, and Financial Barriers co-processing is the rational first reponse to the problem Technical barriers: • Chlorine: potential presence of salts of tire disposal in a country, offering significant capacity. • Flash point: potential presence of solvent traces • As other solutions develop, the cost of used tires is • Homogeneity of the calorific value of waste: potential phase increasing, making shredded tires more expensive separation of solvents compared to other waste segments. • Risk of exceeding the capacity of the steam removal fan Solution: introduce the wastewater in the clinker cooler • A 20 percent thermal substitution rate is achievable in Policy barriers: cement plants with precalciners or preheaters. For a • Complex permit procedure for hazardous wastes with possible cement kiln producing 500,000 tons per year of clinker, opposition from the population this means 12,000 tons per year of whole tires. Recommended Policy Actions Regulation that bans and controls the discharge of wastewater in rivers. Used Tires and Rubber Waste CAPEX and OPEX Origin • Unloading zone for trucks on concrete with collection of spillage • Used tires: tire production and replacement • Tanks in retention basin or double-envelope tanks • Rubber waste from the recycling process (tire cords) • Pumping system for unloading, stirring, and injection • Other rubber waste: from conveyor bands, shoe production, etc. • Filtration by auto-cleaning system or static system on the Composition unloading line • Chlorine: < 0.1% • Electrical devices: must be designed with consideration of the flash point of the solvents (ATEX rules) • Sulfur: around 1.5% • Moisture: 0% (but possible accumulation of water inside the tire CAPEX: €1 million to €3 million depending on the flash point during storage) and size • Metal: iron: 10% to 15%, zinc: 1% to 2%, other: 1,000 to 4,000 ppm OPEX: €5 to €10 per ton • LCV: 26 to 28 gigajoules per ton (23 to 26 gigajoules per ton for Carbon Dioxide Mitigation Potential truck tires) Biomass concentration = 0% Traditional Disposal/Usage Practices Decrease nitrogen oxide production • Retreading: 10% in developed countries, close to 0% in Full replacement of fossil fuels developing countries • Material recovery: use in civil works or rubber recycling • Energy recovery: mainly in cement plants Supply Chains 2.4 USED TIRES AND RUBBER WASTE Collection is the critical issue due to small quantities stored in garages, at tire retailers, or in companies managing vehicle fleets. • Cement plants offer a perfect service for the recycling/ One solution is the creation of a specific network of collectors, recovery of used tires. Used tires are of interest for which could be: the cement process because of their high and constant • The new tire distribution network calorific value, the possibility to recycle the steel as iron • The cement distribution network oxide in the clinkerization process, and the opportunity If extended producer responsibility systems exist, responsibility for collection and treatment is given to producers. to reduce nitrogen oxide emissions at the stack. Many countries have large stockpiles of used tires without • The critical step is collection, given that the resource is official owners. scattered across large areas. Preprocessing and Utilization Technologies • A cement plant can burn whole tires as well as Shredding operation only For large-size tires: extraction of the metallic structure or shredded tires. pre-cutting in large pieces Increasing the Use of Alternative Fuels at Cement Plants: International Best Practice 27 Risk Identification: Environmental Implications and 2.5 INDUSTRIAL SLUDGE Operational Health and Safety Considerations • Generally speaking, industrial sludge is a complex Equipment and operations have to be compliant with environmental regulation related to used tires. problem for waste producers. Because access of sludge to landfills and land spreading is limited, waste producers The main risks are related to storage: • Health risks: mosquito presence (tropical countries) because of often use temporary lagoons as a solution. water accumulation • Co-processing offers a flexible solution by combining both • Fire risks: create several small heaps rather than one large one, use sand (or any high-density mineral) to block fire energy and material recovery. It also is flexible from a • Other risks: Health risks from handling large tires physical point of view because of the capability of receiving liquid, pasty, or solid sludge. The technical evolution Typical Technical, Policy, and Financial Barriers of pumping is bringing new flexibility to this solution, Technical barriers: • Sulfur: limited impact enabling it to now accept a wide range of viscosity. • Management of whole tires: injection and impact on the • Considering the quality of the service and the low calorific process value, the service must be paid for at the right price. Financial barriers: • Competition with other energy recovery processes • This market segment is promising in many countries Policy barriers: for a wide range of industries, such as refineries and • Application for a permit to use waste could be complex and chemical plants. could raise opposition from the population Recommended Policy Actions Industrial Sludge Collection facilitation: Implementing an extended producer Origin responsibility system Ban on tire landfilling: use of tires in civil works would Industrial sludge comes from the treatment of industrial effluent. approximate landfilling and should be strictly controlled There are two kinds of sludge: biological and physico-chemical. Favor material recovery It also comes from tank, pipe, or canal cleaning operations (for example, sewers). CAPEX and OPEX The remediation of old lagoons or storage is also a source of Shredding line: sludge. • CAPEX: €1 million Composition • OPEX: €15 to €40 per ton Composition can vary widely depending on the treatment In the cement plant: Injection of entire tires (precalciner, back end) process. or injection of shredded tires Example of oil sludge (from refineries or drilling): • CAPEX: €1 million to €3 million • Chlorine: 0% to 0.5% • OPEX: €5 to €10 per ton • Moisture: 1,000 to 3,000 ppm Carbon Dioxide Mitigation Potential • Metal: <1,000 ppm Biomass concentration = 25% to 30% • Ash: 10% to 50% Full replacement of fossil fuels • LCV: 5 to 15 gigajoules per ton Traditional Disposal/Usage Practices A wide range of destinations given the potential variety of qualities. Typical destinations are: • Land spreading for inorganic sludge, respecting regulation on pollutant concentration • Landfilling for sludge with low moisture • Incineration • Onsite treatment 28 Comprehensive Information by Alternative Fuel Type Supply Chains CAPEX and OPEX Conventional trucks are used; for basic trailers, the risk of spillage In the cement plant, in case of injection of pasty sludge: must be managed • Unloading pits Preprocessing and Utilization Technologies • Feeding hopper Mechanical drying in the sewage plant • Concrete pump Thermal drying in the sewage plant or in the cement plant • High-pressure pipe to injection line through use of waste heat from the kiln • Special burner Mixing with adsorbents to produce a solid alternative fuel: CAPEX: €1 million to €3 million • Sawdust or some wastes (with high adsorption properties) for OPEX: €10 to €20 per ton organic sludge In the cement plant, in case of injection of dry sludge: • Lime or limestone for oil sludge • Unloading zone for truck Risk Identification: Environmental Implications and Operational Health and Safety Considerations • Vertical silo with explosion protection; in some cases, inertization possible Equipment and operations have to be compliant with • Extraction environmental regulation related to sludge, in some cases hazardous. • Pneumatic injection The main risks linked to industrial sludge are: CAPEX: €1 million • Smell, mainly for biological sludge OPEX: €5 to €10 per ton • Dust pollution in the neighborhood Carbon Dioxide Mitigation Potential • Any chemical hazard linked to the presence of specific chemical Biomass concentration: variable or hazardous wastes in the sludge Oil sludge: biomass = 0% Prevention: personal protective equipment adapted to potential Full replacement of fossil fuels exposures Typical Technical, Policy, and Financial Barriers Technical barriers: • Variability of the calorific value and/or the ash content 2.6 NON-HAZARDOUS INDUSTRIAL WASTE • Variability of the viscosity Financial barriers: • For the cement process, the non-hazardous industrial • Competition with land spreading: cement plants are more waste segment is valuable because it could guarantee flexible (can accept hazardous sludge) and their activity is not large and constant quantities as well as quality. It also seasonal offers the advantage of creating a direct industry- • Competition with incineration: cement plants do not need to dispose of ash to-industry relationship for the waste coming from • The cost of the adsorbent could make preparation costly (case industrial processes. A preparation step is mandatory, of sawdust) involving at a minimum a shredding line that could Policy barriers: conclude with a drying facility; these investments could • Application for a permit to use waste could be complex and be shared between waste producers and cement plants. could raise opposition from the population Recommended Policy Actions • Industrial recycling operations produce wastes that also Regulation on landfilling: could be included in this segment. For example, the paper • A clear regulation defining landfilling must be issued with industry could be a good partner for cement plants. regular controls • Packaging waste from industry is of much higher quality • The rules for landfilling onsite prepared wastes must be clearly defined (in terms of calorific value, moisture, and chlorine) than the packaging waste extracted from municipal solid waste; however, recyclers also demand this higher-quality waste, presenting competition. Increasing the Use of Alternative Fuels at Cement Plants: International Best Practice 29 • Polluted packaging is of particular interest for cement Preprocessing and Utilization Technologies plants. This category includes, for example, chemical Preparation of SRF/RDF in dedicated facilities respecting packaging, oil packaging from garages, and fertilizer regulations related to waste management: packaging. Separate collection of this segment is • Sorting operation becoming mandatory to avoid the spread of pollution, • Drying of the waste and recycling of this waste is not possible. Shredding of Risk Identification: Environmental Implications and Operational Health and Safety Considerations the waste requires a facility that can manage potentially Equipment and operations have to be compliant with low-flash-point solvents, and special fire and explosion environmental regulation related to municipal waste. protections are necessary. The cement plant must apply The main risks linked to industrial SRF/RDF are: for a hazardous waste permit. The service provided to • Fire caused by fermentation: fire detection equipment the customer is paid to the cement plant; this gate fee • Dust explosion: cleaning procedures could, at minimum, cover the preparation costs. Typical Technical, Policy, and Financial Barriers Technical barriers: • Moisture and calorific value Non-hazardous Industrial Waste • Chlorine Origin • Particle size This category covers various sources: • Homogeneity • Packaging wastes Financial barriers: • Process wastes such as pulper wastes in paper recycling • Competition with landfilling due to low landfill gate fee industry • Competition with incineration: incinerator fixed costs are • Off-spec products and product falls expensive, so it must be operated at full capacity to be • Special category for packaging polluted with chemicals; same profitable. However, compared to existing cement plants, approach but including the chemical risks building an incinerator represents a higher investment. Composition Policy barriers: • Application for a permit to use waste could be complex and Main industrial wastes: could raise opposition from the population • Chlorine: 0% to 2% • Regulation that bans any thermal usage: co-processing and • Moisture: 10% to 20% recycling should be complementary (the former using the • Metal: 1,000 to 3,000 ppm wastes of the latter) • LCV: 15 to 25 gigajoules per ton Recommended Policy Actions Pulper wastes: Competition with landfilling: the regulation must limit access to • Chlorine: 0.5% landfilling by technical restriction or taxation • Moisture: 40% to 60% Competition with incineration: • LCV: 6 to 12 gigajoules per ton (20 to 25 gigajoules per ton after • Design of the incineration capacity must be strictly adapted to drying) the needs of residual waste to be incinerated Traditional Disposal/Usage Practices • Priority should be given to existing equipment to increase the efficiency of waste management • Recycling: a leading destination of these wastes when the • For polluted packaging, ban on mixing polluted (considered as wastes are made of mono-product hazardous) and non-polluted • Incineration: with or without energy recovery could be carried out internally and/or in a collective facility • Landfilling: in waste producers’ facilities or external facilities Supply Chains Different options for collection: • Selective collection: source separation of the recyclable fraction, plus waste sorting • Universal collection with transfer stations (especially for small and medium enterprises) 30 Comprehensive Information by Alternative Fuel Type • Creating a network of cement plants is critical to offer CAPEX and OPEX year-round service to the municipality and to properly Shredding operations: • One-step shredding line (granulometry = 50 to 80 mm): manage the annual maintenance stoppage requirements CAPEX: €0.5 million to €1 million + civil works and utilities of cement kilns. OPEX: €15 to €25 per ton • The use of RDF from municipal solid waste is a factor of • Two-step shredding line (granulometry = 20 to 35 mm): integration of the cement plant into the local community. CAPEX: €1 million to €2 million + civil works and utilities OPEX: €20 to €40 per ton, plus cost of chemical management • This segment is very promising for the development for polluted packaging of co-processing. Cement facilities: • For small capacity (1 to 5 tons per hour): CAPEX: €1 million to €2 million Municipal Solid Waste OPEX: €5 to €10 per ton Origin • For bigger capacities (more than 5 tons per hour): Municipal wastes are the wastes produced by citizen activities at CAPEX: €5 million to €15 million home, in their offices, or in commercial areas. OPEX: €5 to €20 per ton The scope of the wording “municipal wastes” could be different including (or not) commercial wastes, non-hazardous wastes Carbon Dioxide Mitigation Potential produced by the industries, green wastes, cleaning wastes from Biomass concentration = 25% to 50% the streets. Full replacement of fossil fuels Composition Composition varies widely depending on the distribution (vertical/horizontal housing, density of population), the districts of the city, the seasons, the organization of collection (selective or not, scavengers or not), the food standards of the city, etc. 2.7 MUNICIPAL SOLID WASTE Standard composition: • Municipal solid waste is produced everywhere in large • Chlorine: 0.5% to 1.5% quantities, and landfilling is becoming less of an option • Moisture: 30% to 45% • Metal: 2,000 to 5,000 ppm for municipalities because of increasing regulation • LCV: 8 to 10 gigajoules per ton and enforcement, existing landfills are at end of their SRF/RDF: capacity, and/or limited land availability. • Quality for main burner • Municipal solid waste must be pretreated to produce a • LCV: 20 to 25 gigajoules per ton suitable alternative fuel (or RDF). The quality produced • Moisture: < 15%, is suitable for precalciner injection. Because of the high • Granulometry: 20 to 30 mm cost of treating the waste for use in the main burner, • Quality for pre-calciner • LCV: 13 to 15 gigajoules per ton this alternative fuel could become too expensive to be • Moisture: 15% to 25% of interest for the main burner. Drying the material • Granulometry: 50 to 80 mm using waste heat from the cement process is an option to • Quality for pre-combustion chamber generate the quality required for use in the main burner. • LCV: 10 to 13 gigajoules per ton • To offer waste treatment and disposal service to • Moisture: 20% to 40% municipalities, different options are possible. One of • Granulometry: 100 to 200 mm the options is to locate the RDF platform in an existing Traditional Disposal/Usage Practices landfill or transfer station and then to send the sorted • Landfilling is the main destination burnable waste to the cement plant for final shredding. • Incineration (with or without energy recovery) Full preparation of the RDF could be done in a dedicated • Recycling is developing everywhere under the pressure of regulation and targets related to the circular economy location close to the municipal collection system. Increasing the Use of Alternative Fuels at Cement Plants: International Best Practice 31 Supply Chains Recommended Policy Actions • Selective collection: source separation of the recyclable fraction Competition with landfilling: and sorting center • The regulation must limit access to landfilling by technical • Universal collection with several transfer stations in big cities restriction or taxation. Collection and treatment responsibility: Municipalities or directly • Policies to encourage proper waste disposal in sanitary landfill, by citizens. Private sector may be involved. enforce illegal dumping/burning, encourage diversion through recycling composting should also be considered. Preprocessing and Utilization Technologies Competition with incineration: Preprocessing in dedicated facilities and respecting regulations related to waste management: • Design of the incineration capacity must be strictly adapted to the needs of residual waste to be incinerated • Sorting lines associated with shredding: extraction of recyclables and organic/inert fraction and shredding of the combustible • Priority should be given to existing equipment to increase the fraction efficiency of waste management • Mechanical biological treatment: production of SRF/RDF Mixing of hazardous wastes, including household hazardous associated with compost production or methanization wastes, must be prohibited. • Drying (biological or thermal): key point to produce alternative CAPEX and OPEX fuel acceptable in cement plant Sorting line with a capacity of 250,000 tons per year: Risk Identification: Environmental Implications and • CAPEX: €1 million to €2 million + €7 million to €8 million for Operational Health and Safety Considerations biodrying Equipment and operations have to be compliant with • OPEX: €5 to €15 per ton depending on the fraction of recyclables environmental regulation related to municipal waste. and the market price The main risks linked to SRF/RDF are: Shredding line and cement facilities: same as for “Non-hazardous • Fire caused by fermentation: fire prevention systems industrial waste” • Dust explosion: frequent cleaning procedures Carbon Dioxide Mitigation Potential Typical Technical, Policy, and Financial Barriers After pretreatment, biomass concentration = 35% to 45% Technical barriers: Full replacement of fossil fuels • Low LCV and high moisture (in cement plant, only used in calciner) • Chlorine: sources are PVC and salt from food. 2.8 MUNICIPAL SEWAGE SLUDGE Financial barriers: • Competition with landfilling due to low landfill gate fees • The market for dried sewage sludge is of interest to • Competition with incineration: incinerator fixed costs are cement plants. expensive, so it must be operated at full capacity to be profitable. However, compared to the use of existing cement • In terms of sourcing, the quantities produced are plants, building an incinerator represents a higher investment. significant and constant. Policy barriers: • The co-processing of sewage sludge must be considered • Application for a permit to use waste could be complex and could raise opposition from the population as a service to the community, with the gate fee • Regulation that bans any thermal usage: co-processing and accounting for the impact of water in the process and the recycling should be complementary (the former using the low calorific value. wastes of the latter) • Co-processing of sewage sludge offers an advantage by allowing for greater flexibility in the chemical composition of the material compared to land spreading. 32 Comprehensive Information by Alternative Fuel Type Municipal Sewage Sludge Typical Technical, Policy, and Financial Barriers Origin Technical barriers: Sewage sludge is produced by sewage plants treating municipal • Low LCV and high moisture or industrial wastewater. Financial barriers: The wastewater is cleaned by biological treatment. The pollution • Competition with land spreading: the cement industry activity is concentrated in the sludge. is not as seasonal as land spreading. After biological treatment, the sludge could be dried by • Competition with power plants or municipal solid waste mechanical treatment (centrifuge or filter press) or by a thermal incinerator: cement plants do not need to dispose of ash, process. other incineration processes need to be compliant with waste Composition incineration Composition depends on the drying process: Policy barriers: • Chlorine: 0.5% to 1% • Application for a permit to use waste could be complex and could raise opposition from the population • Moisture: 40% to 60% raw, 5% to 20% after drying • Ban on phosphorus waste incineration (as in Germany) • Metal: 1,000 to 5,000 ppm, special attention to aluminum and iron Recommended Policy Actions • LCV: 2 to 3 gigajoules per ton raw, 10 to 15 gigajoules per ton Regulation that limits land spreading to sewage sludge with a after drying high potential agronomic value and a low pollutant concentration Traditional Disposal/Usage Practices CAPEX and OPEX Land spreading as fertilizer. Issues: pollutant concentration, CAPEX: seasonality, agronomic value • For pasty sewage sludge: same as for “Industrial sludge” Incineration in different places: • For dried sewage sludge: same as for “Animal meal” • Sewage plant premises OPEX: €5 to €10 per ton • Municipal waste incinerator Carbon Dioxide Mitigation Potential • Power plant Biomass concentration: 100% Supply Chains Full replacement of fossil fuels Conventional trucks are used (tankers for fluids or basic trailers); with basic trailers, the risk of spillage must be managed Preprocessing and Utilization Technologies Mechanical drying in the sewage plant Thermal drying in the sewage plant or in the cement plant 2.9 CONSTRUCTION AND DEMOLITION WASTE through use of waste heat from the kiln • The construction and demolition of buildings creates Risk Identification: Environmental Implications and Operational Health and Safety Considerations opportunities for waste co-processing. In most countries, the natural destination of this waste is landfills because of Equipment and operations have to be compliant with environmental regulation related to sewage sludge. its heterogenous nature. Sorting is key to separating the The main risks linked to industrial sludge are: different components of the waste to extract the burnable • Smell fraction. Although the concept of sorting is emerging in • Dust in case of dry sewage sludge some countries, the economical equilibrium is still not • Any chemical or biological hazard stabilized in countries where the landfilling of inert wastes Prevention: personal protective equipment adapted to potential is inexpensive and not sufficiently controlled. exposures • Depending on the material used for construction, the burnable fraction of this waste can vary widely. Of greatest interest for alternative fuel are the shingles used for roofing in many countries. Windows and doors are of interest only if they are made of wood; plastic windows and doors made from PVC (polyvinyl chloride) are not compliant with cement plant specifications. Increasing the Use of Alternative Fuels at Cement Plants: International Best Practice 33 • For cement companies, which themselves are providers of Risk Identification: Environmental Implications and materials for construction, becoming a player in this waste Operational Health and Safety Considerations segment is an opportunity to implement the concept of a Equipment and operations have to be compliant with “circular economy.” The use of sorted rubble as aggregate environmental regulation related to construction and demolition waste. in concrete activity completes the concept. Special attention to: • Chlorine Construction and Demolition Waste • Ash composition • Appropriate and safe storage Origin Typical Technical, Policy, and Financial Barriers Construction and demolition waste comes from: • Building works Technical barriers: • Building deconstruction • Reliable collection and sorting network: SRF/RDF production, sorting lines close to production places, etc. Main characteristics: Financial barriers: • Huge heterogeneity • Competition with landfilling (the main destination) • Geographical dispersion of the sources Policy barriers: Composition • Application for a permit to use waste could be complex and Depends strongly on local construction materials and could raise opposition from the population deconstruction processes (selective or not) Recommended Policy Actions • Chlorine: depends on PVC content • Regulation that bans the landfilling of burnable wastes or mixed • Moisture: 5% to 10% for plastic wastes, 15% to 20% for paper and wastes cardboard • Standard on aggregates must be revised to allow the use of the • Metal: < 1,000 ppm inorganic part as aggregate LCV: CAPEX and OPEX • Plastic waste: 28 to 35 gigajoules per ton Same as for “Non-hazardous industrial waste” • Paper and cardboard: 10 to 15 gigajoules per ton • Mix of industrial wastes: 15 to 20 gigajoules per ton Carbon Dioxide Mitigation Potential Traditional Disposal/Usage Practices • Wood fraction: biomass concentration = 100% • Average wastes: biomass concentration = 10% to 50% • Landfilling: private or municipal landfills • Full replacement of fossil fuels • Backfilling in aggregates quarries or embankment (for pure rumbles) • Material recovery: wood, concrete (aggregate), metals, etc. • In some countries, sorting line to extract material with value on site or at a dedicated location 2.10 BIOMASS AND GREEN WASTES Supply Chains If landfilling is restricted, collection is favored. Demolition and • The opportunities in the biomass sector are multiple and construction wastes are often collected in bins. heterogeneous but potentially highly volatile. Preprocessing and Utilization Technologies • Competition in this waste segment comes from many Sorting operations allow for extraction of different fractions: potential uses, including combined heat and power doors, windows, shingles, wood parts, plaster board, etc. plants, methanization, livestock feed, and local heating. Shredding of the extracted fractions for alternative fuel production: In some countries, the subsidization of green electricity • Special attention to plastics because of PVC (risk of chlorine offers an advantage to the power sector in use of pollution) biomass feedstocks. • Hazardous wastes can be used in cement plants after shredding • For agricultural or green waste, the sourcing is often local to maintain a competitive position, as transportation costs can make use of this waste uncompetitive. 34 Comprehensive Information by Alternative Fuel Type • A strategic approach that includes the collection and Preprocessing and Utilization Technologies transport of biomass and even agroforestry waste would • Physical modification: grinding and pelletization give an advantage to the cement sector. Diversification of • Moisture reduction: solar or thermal drying (the latter is possible the biomass is a key factor to secure sufficient sourcing. in the cement kiln) • Calorific value concentration: carbonization and roasting Biomass and Green Wastes Risk Identification: Environmental Implications and Operational Health and Safety Considerations Origin Storage must be managed properly to avoid: Agricultural residue categories: • Rodent infestation • Field-based residues, coming from farming activities: stalks, • Fire caused by direct inflammation or fermentation straw, chicken litter, tops and leaves • Flying dust that could pollute the neighborhood • Process-based residues, coming from transformation processes: husks, bagasse, glycerin, sawdust Typical Technical, Policy, and Financial Barriers These wastes, especially the first category, are scattered over Technical barriers: large territories. • Low LCV: mitigated by drying, torrefaction, or carbonization Composition • Collection: could be managed by cement plant team Composition varies widely depending on the kind of waste. • Low density: storage and handling facilities should be adapted Some examples: to big quantities Coffee husk: • Ash concentration in biomass (20% to 50% on dry): low LCV, • Chlorine: < 0.5% chlorine concentration (1% to 5% on dry), silica concentration, etc. • Moisture: 10% to 20% Financial barriers: • Ash: presence of silica • Competition with energy recovery for internal uses: low yield, poor-quality emissions • Grain size: < 15 mm • Competition with energy recovery for external uses (power • LCV: 17 gigajoules per ton dry stations): high financial investment, high biomass quantity Chicken litter: needed • Chlorine: 0.4% to 0.8% Advantages of cement plant: high energy efficiency, no ash, • Moisture: 15% to 30% localization near production sites, low financial investment • Ash: 10% to 30% Recommended Policy Actions • LCV: 10 to 13 gigajoules per ton Ban biomass burning directly in the field Glycerin: Promote safe usage of biomass • Chlorine: marginal Develop network of information centers for the farmers • Moisture: 5% to 10% CAPEX and OPEX • Ash: 0% Same as for “Non-hazardous industrial waste” • LCV: 25 to 35 gigajoules per ton Carbon Dioxide Mitigation Potential Traditional Disposal/Usage Practices Biomass concentration = 100% Burning on-site: small quantity and field-based residues. Full replacement of fossil fuels • Ashes used as fertilizer • Prevent the spread of diseases Cattle feeding: directly or after transformation 2.11 ANIMAL MEAL Energy recovery: an important destination for these wastes, considering the calorific value • Cement plants were the main destination for potentially Supply Chains tainted animal meal during the “mad cow” crisis of For crop wastes, collection is a key point. Two parameters must the 1980s and 1990s. Following reorganization of the be considered: treatment chain, animal meal is now returning to its • Low density: 0.1 tons per m3 or less initial destinations, and only small fractions remain in • Resource dispersion: small quantities and large areas. co-processing. Collection could be optimized by implementing transfer stations. The stations must be managed properly to avoid exposure to rain. Increasing the Use of Alternative Fuels at Cement Plants: International Best Practice 35 • The market for animal meal is a spot market, making it Typical Technical, Policy, and Financial Barriers necessary to set up handling and storage facilities that Technical barriers: are compatible with different waste streams, as is also the • Resource quantity can vary widely depending on authorizations case for biomass and dried sewage sludge. or bans during crisis (for example, mad cow) Policy barriers: • Application for a permit to use waste could be complex and could raise opposition from the population Recommended Policy Actions Animal Meal Fundamental role of regulation: Origin • Clear definition needed of the different qualities as well as the Animal meal is produced in rendering plants, which are in charge allowed destinations of managing waste from cattle, slaughterhouses, and meat • Strong enforcement also required for the whole chain from production. animal wastes to the final destination. Regulation defines quantity authorized to be used for energy recovery. Authorized categories depend on the risk of disease CAPEX and OPEX outbreaks. Facility required is a silo and an injection line to the main burner: Composition CAPEX: €0.5 million to €1 million • Chlorine: < 0.5% depending on the cleaning strategy in the OPEX: €5 per ton rendering plant Carbon Dioxide Mitigation Potential • Moisture: 10% to 20% Biomass concentration = 100% • LCV: 15 to 17 gigajoules per ton Full replacement of fossil fuels Special attention to fat concentration: if fat > 15%, then risk of clogging in cement plant Traditional Disposal/Usage Practices • Traditional destination is the feeding of different species of animal or fishes after the animal meal is certified free of disease • Use as fertilizer, given the high agronomic value • Energy recovery is the main destination in case of health crisis (for example, the “mad cow” crisis) or in case of ban from other uses for overproduction reasons Supply Chains Transportation: • Most convenient solution is tanks (and silo storage at production sites) • Trailers could be used, but this requires more complex facilities in the cement plant: hopper and transfer to silo Preprocessing and Utilization Technologies Preprocessing is performed in rendering facilities Recommendation: no preparation step in the cement plant Risk Identification: Environmental Implications and Operational Health and Safety Considerations Storage must be managed properly to avoid: • Rodent infestation • Fire caused by direct inflammation or fermentation • Explosion because of flying dust: silo design must be adapted • Hopper must be located in a building to avoid contact with water and outside dissemination of smell 36 Comprehensive Information by Alternative Fuel Type KEY SUCCESS FACTORS FOR ALTERNATIVE FUEL PROJECTS 3 The success of an alternative fuel project depends on a (especially for pollution, health, and safety) of waste combination of several key factors, which can be either treatment in a cement plant located close to their homes. powerful levers or prohibitive barriers depending on how well Such an approach should be based on regular exchanges or poorly they are controlled. Those key factors are discussed between the cement plant and the surrounding community. below, followed by a special focus on municipal waste. • The success of a project requires a good knowledge of the various waste sources that are available at a 3.1 SUCCESS CRITERIA FOR ALTERNATIVE FUEL competitive price. It therefore is imperative to analyze PROJECTS and understand the market in the country. The selection • Probably the most important factor in the success of a of wastes should not be based on the experience and co-processing project is the commitment of management, technical know-how of cement manufacturers. This starting with the cement plant manager. It is fairly easy analysis should include an economic assessment that for an unmotivated management team to argue that allows cement producers to define how to approach substitution of fossil fuels is not possible or entails the market. Cement producers often have the choice to additional and prohibitive costs. The management develop their own supply or to partner with one or more team must leave its comfort zone and understand that players already in the waste sector. the use of waste as fuel is primarily a service offered to • All cement plants are not equal in their ability to replace waste producers. This practice is not comparable to the a significant portion of their fossil fuel use. The type traditional procurement process for fossil fuels. of process, quality of the raw material, nature of the • The use of waste in cement plants has been, and still fossil fuel used, and behavior of the kiln all have a direct is, the subject of numerous attacks by specialized influence on the feasibility of a project. Understanding incinerators. Opponents of co-processing highlight unfair phenomena and process control are key success factors. competition because of different levels of investment, Some cement kilns are not able to achieve the substitution and they engage in lobbying to support regulatory rate specified for a project. Analyzing the kiln’s ability to barriers against co-processing. The cement sector has replace its fossil fuel is a precondition of any project. had to organize itself to tackle these barriers. If this issue • Control of waste pretreatment is critical to the quality has mostly been addressed in industrialized countries, and regularity of alternative fuels. For instance, a poorly the capacity of cement plants to respond to regulatory controlled liquid mixture can result in large variations in changes in countries that do not yet have co-processing calorific value. It therefore is imperative that the operator remains a key success factor. Downstream of the of a pretreatment facility manage its production with a regulatory framework, permitting the use of waste as strong knowledge of the constraints of the cement kilns alternative fuel is often a long and complex process that that it supplies. Similarly, the cement producer must be needs to be managed. familiar with delivery check techniques as well as the • The establishment of transparent dialogue and trust unloading, storage, and handling of waste. The quality of relationships with stakeholders, particularly local dialogue between the two actors is key to the success of residents, is crucial for the success of a project. Local the operation. residents have the right to understand the implications Increasing the Use of Alternative Fuels at Cement Plants: International Best Practice 37 4 FOUR CASE STUDIES OF ALTERNATIVE FUEL USE The presented case studies were selected based on their POSITIONING OF CEMENT PLANTS IN THE relevance to the Brazilian cement sector as expressed by the MUNICIPAL SOLID WASTE SEGMENT leading cement players in the country. Cement plants could offer a service for waste management through the preparation of refuse-derived fuel (RDF) (also 4.1 MUNICIPAL SOLID WASTE known as solid refuse fuel (SRF) or solid shredded wastes 4.1.1 COMPOSITION OF MUNICIPAL SOLID WASTE (SSW)) or Process Engineered Fuel (PEF) out of some fraction of the municipal solid waste. The composition of municipal solid waste depends on the following factors: The positioning of cement plants could vary depending on how the waste is collected (see Figure 27): • The scope of waste collection in a given city, including waste produced by: • In the case of universal collection, RDF preparation will • The general population start with a sorting line to extract first the recyclables • Shopping malls and other commercial areas (more and then the combustible fraction. The extraction of the packaging means more recyclables and higher combustible fraction is performed either by a negative calorific value) collection means (removing the biodegradable fraction • Technical workshops that provide services to and fine particles with a sieve, with the remainder going the population, such as automotive garages, to RDF production) or by a positive extraction means maintenance and repair shops, and restaurants (manually extracting the fraction for RDF production, (with related risk of hazardous wastes) with the rest going to landfill or incineration). • Industrial zones with small and medium enterprises • In the case of selective collection, the extracted fraction is (more packaging means more recyclables, higher calorific value, and risk of polluted wastes). sent to a second sorting operation to further separate the materials (such as paper, plastics, textiles, cardboard); • The waste collection logistics, for which two main the remaining fraction often presents a calorific value approaches exist: favorable to RDF production. The remainder after • Universal collection selective collection is treated the same way as for • Selective collection for recycling and other uses universal collection, but without sorting of recyclables, (in the case of packaging waste, the material that only negative or positive selection to extract the burnable remains after collection will have a lower calorific fraction. value, and in the case of green or organic wastes, the portion that remains will have less moisture • It should be noted that recycling activities also produce content). wastes with a high calorific value for the production of RDF. Close association with these activities is therefore • The structure of the city and its suburbs (horizontal or of interest. vertical density structure). 38 Four Case Studies of Alternative Fuel Use Figure 27: Schematic Definition of the Collection and Sorting Systems Leading to RDF Production Municipal solid waste: household wastes/commercial and industrial wastes Universal Selective collection collection Unsorted wastes Unsorted fraction Sorted fraction Second sorting Landfill incineration Pre-treatment Non-recyclable Compost, landfilling Recyclable of stabilized wastes RDF Recycling activity RDF RDF Calciner Quality (12-17 GJ/t) Main Burner Quality (18-23 GJ/t) Source: Sofies AS. 4.1.2 QUALITY OF REFUSE-DERIVED FUEL A new technology is emerging in the cement process that would enable the kiln to receive very low-quality RDF. Considering the low calorific value of raw municipal solid This technology is based on installing a pre-combustion waste, the selection of the waste used to produce RDF is a key chamber before the calciner to burn the waste before it is point, and there are possibilities to create different qualities of introduced into the process. This pre-combustion chamber RDF suitable for different injection points in the cement kiln. could be based on a rotary sole or step burning, as in a Usually, cement companies consider two qualities defined by waste incinerator. This technology is aimed at receiving the calorific value and the granulometry: wastes with low calorific value (10 to 13 gigajoules per ton) and larger size (up to 300 millimeters), which would greatly • RDF for the calciner (calorific value: 12 to 17 gigajoules per reduce preparation costs. Several pilots are now in industrial ton; granulometry: 50 to 80 millimeters) operation. This quality is the most important and could be produced 4.1.3 PREPARATION OF MUNICIPAL SOLID WASTE after stringent selection and sieving without drying but will represent a limited fraction of the source (25 to 35 percent). A cement plant will have several options for starting In the case of drying (thermal or biological), production of co-processing using municipal solid waste. Among these, this quality could reach 50 percent of the input. we have selected three that could be considered as key steps of development: the pilot step, the development step, and • RDF for the main burner (calorific value: 18 to 23 mechanical and biological treatment. For these examples, we gigajoules per ton; granulometry: 20 to 35 millimeters) assume the production of 500 kilotons of RDF per year. This quality will be limited and will require either a significant fraction of commercial and industrial waste and/ or refuse from recycling operations or a drying operation. Increasing the Use of Alternative Fuels at Cement Plants: International Best Practice 39 PILOT STEP costs. The fraction could be shredded on-site or in the cement plant. This step is focused on the production of RDF from municipal solid waste (see Figure 28). The quality of the fuel DEVELOPMENT STEP is obtained through strict selection of the waste in order to This option is aimed at obtaining larger quantities of RDF implement a process that is as simple as possible to produce and preparing the two alternative fuel qualities that are the RDF in the context of a low gate fee for the waste. This usable in a cement plant (see Figure 29). This preparation pilot step would include a sorting line (with bag opener) is compatible with other waste management solutions, such to extract those recyclables that have a market value and as a waste incinerator, a composting plant, or a landfill. then engage in negative or, even better, positive selection The preparation would start with the selection of trucks to extract the combustible fraction of the waste. The based on the different collection routes. Depending on the combustible fraction is sent to a shredding line comprising collection logistics, it could make sense to set up an initial one or two steps of shredding with a sieving machine and an separation step to extract the large pieces in instances where over-band magnet conveyer to extract the larger parts and more potential recyclables are present. This fraction is sent metallic pieces. to a sorting line to extract the recyclables that can generate With this process, the RDF will have a calorific value revenue for the treatment chain. of about 15 gigajoules per ton and a particle size of 80 To produce the two RDF qualities important for the cement millimeters. The quantity produced will represent between plant, and considering the moisture content of the waste, a 10 and 25 percent of the raw municipal solid waste. drying operation is required. The drying operation is more The sorting operation could be performed at the landfill that efficient with shredded waste, and pre-shredding could take initially receives the municipal waste, to reduce transport place before drying. The drying operation could be thermal or Figure 28: Schematic of the Sorting System for the Preparation of Municipal Solid Waste Municipal solid waste (MSW): example for production of 500 kilotons per year (First Step) Sorting by origin or visual inspection MSW 100 Kt/yr MSW Bag opener / Manual sorting 400 Kt/yr 5–10 Kt/yr 40 Kt/yr Recyclable fraction Burnable fraction 50 Kt/yr Screening Shredder Landfill Recycling activities Kiln feeding back end Municipality or subcontractor Cement plant or joint venture with waste management company Cement plant Source: Sofies AS. 40 Four Case Studies of Alternative Fuel Use Figure 29: Schematic Showing the Preparation of Municipal Solid Waste with Thermal Dryer Municipal solid waste: example for production of 500 kilotons per year (Demonstration Step with thermal dryer) Truck selection 250 Kt 250 Kt 60 Kt Bag opener Incineration Landfill 40 Kt Coarse 125 Kt Manual sorting Tromel or sieve Screen 2*20 t/h 80/100 mm 110 Kt 150 Kt Fine 125 Kt Thermal Dryer Second-step shredder Coarse 15 Kt 225 Kt Recyclable Pre-shredder Dryer main burner Precalciner 30 Kt–60 Kt 60Kt Municipality or subcontractor Cement plant or joint venture with waste management company Cement plant Source: Sofies AS. biological, with the former requiring a source of energy but There are several concepts of MBT plants. The initial idea less volume, and the latter requiring more volume, given the is to optimize the separation of the different constituents time required for the bacterial activities. After drying, a sieve of municipal solid waste into four parts: recyclables (paper, is helpful to extract the inert fraction to be sent to landfill. plastics, metals, textiles), organics (food rejects, green wastes), combustibles (mixed materials or materials with The waste must be submitted to a second step of shredding, high moisture content or without an attractive selling price), mainly to provide the quality of material necessary for use and inerts (ash, bricks, stones). The distribution of the in the main burner. The calorific value required for the main fractions depends on the composition of the waste and on burner will be secured, just before feeding the main burner, the availabilities of the outputs. by a simple belt dryer using the waste heat of the kiln. After the initial sorting steps, two treatment lines occur MECHANICAL AND BIOLOGICAL TREATMENT PLANTS (see Figure 30): The mechanical and biological treatment plant (MBT) will treat the entire volume of municipal solid waste. Cement • A mechanical line to prepare the RDF and extract the companies are not typically motivated to adopt this process, recyclables, and as RDF is only one of the potential outputs of the process; • A biological line to prepare the compost through aerobic one potential exception is the case of a cement plant using treatment or, less commonly, to prepare biogas through a quarry as a landfill for stabilized wastes in the context of anaerobic treatment. quarry rehabilitation. The bio-drying also could be included in the first step. Then, sorting is done to extract the organic fraction. In the case Increasing the Use of Alternative Fuels at Cement Plants: International Best Practice 41 Figure 30: Schematic of Biodrying Process for Municipal Solid Waste Municipal solid waste Preparation Shredding and/or first sorting Extraction Thermal drying of organics or biodrying Biological Sorting and/or treatment second-step shredding Aerobic Anaerobic Stabilized wastes for landfilling Compost Biogaz Rejects RDF/SRF Recyclables Source: Sofies AS. of no outlet for the compost, because of its low quality municipal solid waste). The cement company’s involvement or its non-compliance with land spreading, the biological could be managed by the creation of a joint venture with treatment is simplified as stabilization to make the waste a waste operator, by sharing some investment, or through compatible with landfill regulation. the delegation of a quality/production manager inside the preparation platform. Additionally, involvement of the 4.1.4 BUSINESS MODELS cement company in the RDF production entity can make the The involvement of the cement company in RDF production deal more bankable for financing, as offtake arrangements depends on the strategy of the cement company and on can be stronger and longer term. the quality of the relationship created with the operator of the preparation step and/or the municipality. The cement The continuity of the service offered by the cement plant is company will consider the sustainability of waste sourcing in also a critical topic. Municipal solid waste must find a year- terms of quantity and quality. In some countries, contracting round destination. To manage the waste stream during annual provides sufficient confidence to the cement company: the kiln stoppages for maintenance, possible solutions including contract must set the technical and economic conditions as forming a network of cement plants; sharing the waste volume well as guarantees on the outputs. In other countries, the with another buyer, such as incineration; and landfill or cement company prefers to be involved in pretreatment to storage in bales in the case of a short stoppage period. have strong control over the quality; in some cases, even the Management of the informal sector could be critical to final shredding will take place at the cement plant to allow the success of the RDF production concept. Involving the the plant to maintain the flexibility needed for different informal waste pickers in the advanced RDF production, sources of RDF (where it makes sense to separately collect along with municipality or a waste management company/ non-polluted industrial and commercial waste alongside 42 Four Case Studies of Alternative Fuel Use RDF producer by offering formal employment in the sorting • There is a strong willingness to develop recycling in lines could be a win-win solution, which can improve the cooperation with the existing organization responsible working conditions dramatically. for recycling (waste pickers or at the landfill). 4.1.5 CONDITIONS FOR AN ALTERNATIVE FUEL • There are potential buyers for recyclables at attractive prices. PROJECT USING MUNICIPAL SOLID WASTE CRITERIA FROM THE CEMENT PLANT SIDE The success of an alternative fuel project depends on a • The cement plant is not sold out for clinker production. combination of criteria, including existing regulations on waste and industry, economic factors, technical knowledge, • The cement plant offers a capacity to absorb extra and good cooperation between different industrial sectors quantities of chlorine (and sulfur). and public institutions. • The cost of the fossil fuel is high enough to motivate the use of alternative fuels, or the alternative fuels are As discussed previously, for municipal solid waste, one of the cheaper than traditional fossil fuels. most promising waste segments, the following criteria will contribute to a successful project associating a municipality • The cement plant management shows a strong and a cement plant. willingness for technical development of alternative fuels. CRITERIA FROM THE MUNICIPALITY SIDE • There is no existing conflict with stakeholders of the cement plant. • The existing waste disposal site is a landfill that has a significant 4 gate fee (including transfer and/or • The cement company is willing to pay a reasonable price transport costs). and price adjustments for the RDF at the specification level, with sufficient contract term. • Municipality is creditworthy and/or has a history of on time payment to the private sector for waste or other The proximity of the city and the cement plant also helps to infrastructure services. create the conditions for a viable project. These criteria may • The municipality is facing difficulties in or the include, for example: impossibility of opening new landfills or increasing the • A city with between a half million and 1 million inhabitants; capacity in existing ones. • A cement plant with a kiln capacity of at least 1 million • The municipality is in charge of waste collection tons per year; and disposal, even if the execution of these tasks is subcontracted. • Distance between the city and the cement plant of less than 100 kilometers. • The contract with the landfill operator presents no incentive (direct or indirect) to increase the quantity of waste landfilled and/or is open to possibilities for renegotiation. • A piece of land is available for the creation of a sorting line somewhere either at the landfill or at a transfer station. 4 In many emerging markets, a “significant” gate fee may not be available. However, that does not mean that an RDF production facility cannot be considered. Simpler, lower CAPEX approaches may be required, or a plan needs to be in place to increase the tipping fee. Increasing the Use of Alternative Fuels at Cement Plants: International Best Practice 43 4.2 SEWAGE SLUDGE • Anaerobic Digestion (AD)5 to produce methane that is used 4.2.1 DESCRIPTION OF MUNICIPAL SEWAGE SLUDGE to generate power and also used directly in thermal engines Sewage sludge is produced by water treatment facilities that • Composting mixed with organic wastes to increase its collect the wastewater from a city’s sewers, including from possible use as fertilizer local industries and in some cases from small and medium • Drying to reduce the volume and to concentrate the enterprises. The wastewater is treated through physical and calorific value biological methods, and the organic content is concentrated • Incineration to reduce the volume and to produce heat. in sludge that is submitted to biological treatment to enable degradation of any pollutants. 4.2.2 POSITIONING OF CEMENT PLANTS IN THE MUNICIPAL SEWAGE SLUDGE SEGMENT Historically, treatment ended at this stage, and the most Cement plants could offer a service for sewage sludge common destination for the sludge was land spreading, which management at different stages of its production, with is still widely used in small cities that have nearby fields and varying interests and uses in the cement process as follows where farmers are available to accept the sludge. However, (see Figure 31): these conditions are becoming more difficult to find in many countries, and sewage plant operators are now forced to seek • The sludge produced after mechanical drying via a filter, alternative solutions by decreasing the volume of municipal screw, or centrifugal press: Because the moisture content sewage sludge and extracting more value from it. is still high, the calorific value is low. As a consequence, The sludge could be treated using varying solutions: 5 Bio-methanization usually refers to the process of producing methane through AD and cleaning it up to natural gas specification levels. Figure 31: Schematic of Drying Process for Municipal Sewage Sludge Municipal sewage sludges (MSS) Digestion Methanisation Mechanical Wet MSS Drying Calciner (5–8 GJ/t) Landspreading or Incineration in power plant or municipal solid waste incinerator Dry MSS Main Burner or Calciner Thermal Drying (10-13 GJ/t) Ashes Incineration ARM Source: Sofies AS. 44 Four Case Studies of Alternative Fuel Use the quantity is limited (1 to 5 tons per hour), and the Digestion could reduce the calorific value of the sludge. cement plant must be paid for providing this service. Methanization introduces a decline in the calorific value, making the sludge less appealing for cement plants. • The sludge produced after thermal drying (in some countries, it could be solar drying): The lower moisture The concentration of heavy metals must be controlled. The content of the dried sludge has a lower negative impact sewage plant potentially could receive wastewater with a on the kiln process. The quantity could be increased high concentration of metals from local industries involved to 10 tons per hour, provided that the impact of the in metal finishing or leather treatment. ash is managed. The cement plant can be used as a key destination for a municipality. The transport cost also Management of the smell must be taken into consideration would be substantially lower. during the design of the facility within the cement plant. • The ash from a sewage sludge incinerator: The potential The risk of smell is much higher in the case of wet municipal use of this ash in cement plants is limited to its use as an sewage sludge. alternative raw material, provided that the composition A new concern is emerging about the phosphorus is compatible with the raw mix composition of the concentration of municipal sewage sludge. Germany plans cement kiln. to ban the incineration of sewage sludge that has not Generally speaking, cement plants are not interested in undergone phosphorus extraction. raw sludge that has not undergone mechanical drying (via Dried municipal sewage sludge could be produced as a filter press). The quantity that is usable in a cement plant is powder or pelletized. Pelletization is making transport marginal compared to the quantity produced; a community easier (in traditional trailers versus tanks for powder), but cannot be interested in this service except in the case of a a grinding step (via hammer mill) often is mandatory to small village where the cement plant is located. In addition guarantee good burning conditions as the material is injected to a gate fee, which is expensive given the high moisture into the main burner. content of the waste, the transport cost is becoming too high for transporting what is considered to be mainly water. 4.2.4 PREPARATION OF MUNICIPAL SEWAGE SLUDGE 4.2.3 QUALITY OF MUNICIPAL SEWAGE SLUDGE Internationally, a few cases exist of cement plants installing The quality of municipal sewage sludge is linked to the dryers that use the waste heat from the kiln. This concept process used in the sewage plant (see Table 3). has been implemented in Germany, where the gate fee for wet municipal sewage sludge is expensive and where several Table 3: Type of Municipal Sewage Plant Affects Quality Calorific Value Water Content Type of Sludge (gigajoules per ton) (percent) Other Characteristics Wet 0–5 30–50 Ash: 5% to 10% Phosphorous: <1% Chlorine: <0.2% Dried 10–13 5–10 Ash: 20% to 25% Phosphorus: <1% Chlorine: <0.2% Ash 0 0 Inorganic composition: silicon dioxide; aluminum oxide; iron oxide; trace elements such as zinc and copper Source: Sofies AS. Increasing the Use of Alternative Fuels at Cement Plants: International Best Practice 45 medium-size cities are looking for an alternative to explosion risk. It is usable for sawdust, animal meal, black land spreading. carbon, and rubber dust/granules. Technical solutions in the cement plant have been developed for ASH wet and dry municipal sewage sludge, and for ash, as follows: The ash can be mixed directly into the raw mix. WET SLUDGE 4.2.5 BUSINESS MODELS The wet sludge (mechanically dried) can be injected at the The decision-making process in the municipal sewage back end of the kiln. Considering the viscosity of the sludge, sludge segment is often complex and lengthy, and pumping must be undertaken using a concrete pump that municipalities often ask for long-term commitments. This is adapted to sludge. The pipe must be designed to manage represents an advantage for cement plants in terms of high pressure. Storage could be in a rectangular silo with sustainability of sourcing and amortization of the requested an extracting screw at the bottom feeding a piston pump investment in the plant; however, pricing must take into (see Figure 32). consideration the potential evolution of the waste market, with smart revision systems. DRY SLUDGE The facility for dry municipal sewage sludge comprises: The continuity of the service offered by the cement plant is also a critical topic. Municipal sewage sludge must find a destination • A reception hopper, screw conveyor, or bucket elevator year-round; to manage the waste stream during annual kiln • A weigh belt stoppages for maintenance, options including creating a network of cement plants and sharing the sludge resource with • A silo for management of dust and explosion risk another solution, such as incineration or landfills. • Pneumatic transport to the calciner or main burner (for 4.2.6 EXTENSION TO INDUSTRIAL SLUDGE pellets, a grinder is recommended). All industries must manage their wastewater and could This kind of facility has the flexibility to receive different operate wastewater treatment plants. If biological treatment is types of waste in pellet or powder form, provided that the performed, which is common in the chemical, pharmaceutical, silo design takes into consideration dust management and and agro-industries, the industrial sludge produced could Figure 32: Picture and Schematic of Sewage Sludge Processing Unit · · + -   Source: Document Putzmeister/Lafarge. 46 Four Case Studies of Alternative Fuel Use be used in a cement plant in the same facility that uses wet fossil fuel price. Given the current low prices of both municipal sewage sludge. Refineries and steel industries carbon and fossil fuels, biomass projects could produce oil sludge that also is compatible with such facilities. be impacted. Industries often pay a lower gate fee than municipalities because alternatives such as land spreading frequently are not Despite these barriers, biomass waste remains of interest for allowed for industrial sludge, but the contracts are often of supplying energy in the cement industry. As seen in Section shorter duration than for municipal sewage sludge. 2.2.4, biomass alternative fuels are used widely in cement plants, substituting completely for costly fossil fuels that A mixture of these two different sources would provide release carbon dioxide to the atmosphere. Experience has cement plants with greater comfort in the sustainability of proved the real feasibility of using biomass as an alternative their sourcing. fuel in cement production. 4.3 BIOMASS This section will describe some of the critical points for implementing pilot projects using agricultural residues in the 4.3.1 DESCRIPTION OF BIOMASS WASTE cement industry. Many different potential sources of biomass waste exist, such as sugarcane straw, coffee husks, and food oil waste. 4.3.2 POSITIONING OF CEMENT PLANTS IN BIOMASS SOURCE COLLECTION These can be divided among the three categories of waste discussed earlier: field-based sources, process-based sources, First, it is important to identify the production areas for this and waste sources (see Section 5.2). Because biomass waste resource, as biomass waste or residue production tends to be is made of 100 percent renewable organic matter, it has high concentrated in specific regions. potential for mitigating carbon dioxide emissions from the cement industry. Secondly, it is important to quantify and evaluate the local waste sources. Because local biomass sources already may However, some challenges remain: be used for local purposes, these competitive uses and the owners of the production sites need to be clearly identified. • Heterogeneity: For each residue, the quantity and quality can vary widely because of different characteristics such • Coffee production: as crop or animal variety, weather, and farming region. • In Brazil, there is one harvesting season, which • Geographical dispersion: Biomass waste sources often covers May to August for Robusta and Arabica. It should represent about four or five months of coffee are dispersed over large territories, making collection husk supply for a cement plant. expensive. • Weather, especially rainfall, can greatly affect coffee • Seasonality: Because most agricultural residues are production and thus the stability of the resource. A produced only during harvesting periods, this could severe drought in 2015 sharply reduced Brazilian be an issue for a cement plant that needs a year-round coffee production. energy supply. • Sugarcane production: • Existing competitive uses: Most of the time, biomass • In Brazil, sugar cane (and the associated residue) wastes already are used locally for energy purposes, for is produced nine months a year. Cement industry livestock feed, or as fertilizer. Even if using them in the activity stops one month a year for maintenance. cement industry may be more efficient, other competitive With storage infrastructure adapted for two months, cement plants could be supplied with sugarcane uses exist. residues year-round. • Profitability: The profitability of a biomass-based project • Although bagasse is used as a fuel for steam depends strongly both on the carbon price and on the generation (see Table 4), this energy potential Increasing the Use of Alternative Fuels at Cement Plants: International Best Practice 47 remains under-exploited. Moreover, some sugar plants would save €4 per ton of clinker by replacing producers do not consume all of the bagasse they fossil fuels with sugarcane straw. produce, selling the surplus to other users. • It could be laborious to sign an agreement with each • The sugarcane tops and leaves (sugarcane straw) small producer. In Brazil, supply agreements with appears to be relatively unused, with most of it producers could be easier for sugarcane straw collection disposed of in the field. Assessments suggest that, at most, only 50 percent of the straw is required to because the same large companies often own both the maintain the soil’s agronomic value. production and processing infrastructure. Finally, a collection network can be implemented. Collection 4.3.3 QUALITY OF BIOMASS ALTERNATIVE FUELS is the most critical step and needs to be studied carefully The composition varies widely among the different biomass to tackle the main challenge: potentially high collection alternative fuels. costs. Collection expenses can be high because of scattered resources and low biomass density. The two means of With regard to our selected biomass resources, the collection are local collection and centralized collection. approximate quality characteristics are shown in Table 4. • In Uganda, Lafarge has implemented a special collection system for coffee husk recovery, using the existing cement distribution network to reduce the collection cost. First, husks are collected locally and consolidated in the cement intermediary storage areas (the green circles on Figure 33). Next, trucks that return empty from cement deliveries transport the husks from the intermediary areas to the cement plant (the red circle in the figure). • Despite the collection cost, the use of agricultural residues could be profitable. Lafarge assessed that cement Figure 33: Map of the Coffee Husk Collection Network in Uganda 26,486T 20,282T 55,037T 46,593T Total Tonnage = 148,398 Source: Sofies AS. 48 Four Case Studies of Alternative Fuel Use Table 4: Quality Characteristics of Selected Biomass Calorific Value Moisture Content Ash Type of Biomass (gigajoules per ton) (percent) (percent) Other Characteristics Bagasse 7.8 50 3.2–5.5 Phosphorous: 0.73% to 0.97% Chlorine: 0.05% to 0.2% Sulfur: 0.10% to 0.15% Sugarcane stalk 15 20 7.7 Chlorine: 0.3% to 0.5% Coffee husks 17.5 (dry) 10–20 2.5; presence of silica Chlorine: <0.5% Sulfur: 0.2% Grain size: <12 millimeters Source: Sofies AS. 4.3.4 PREPARATION OF BIOMASS ALTERNATIVE • For precalciner kilns, the injection could be realized to FUELS the riser duct at the same level, but on the opposite side, Generally speaking, preprocessing is fairly simple. of the existing coal feed points. 4.3.6 MAIN STEPS TO IMPLEMENT A PILOT PROJECT • The storage capacity should be adapted to low biomass BASED ON BIOMASS SOURCES density and seasonality. The critical points are the supply chain and collection, for • Depending on the biomass residue, drying or shredding the reasons explained above. steps could be implemented. It also is important to tackle social and environmental issues: • Some of the alternative fuels are roasted or carbonized to concentrate the calorific value. Even if it is an added cost, • Indirect changes in land use may have an impact on roasting is of interest for two main reasons: greenhouse-gas emissions. • It increases the calorific value • In Brazil, sugar cane is used in large quantities for biofuel generation. This can create competition with • Roasted biomass can be co-injected in the kiln directly with coal, obviating the need for other food production and increase food prices. Cement plants preparation infrastructure such as a supplementary should keep in mind these elements before implementing shredder or multi-fuel injection system. an alternative fuel project. 4.3.5 TECHNICAL CONSIDERATIONS FOR BIOMASS • In poor countries where child labor remains significant, INTEGRATION IN THE CEMENT PROCESS cement plants should make sure that no children would be exploited in the fields. Direct feeding for low-density material (0.1 to 0.3 tons per cubic meter): it is possible to introduce the alternative fuels 4.4 INDUSTRIAL WASTE directly without additional processing. Typical hazardous solid wastes include oily sludge and the • This includes coffee husks, rice husks, bagasse, sugarcane spent catalysts and solids from air pollution control systems. straw, and sunflower shells. Oily sludge has a liquid and pasty consistency and complex chemical composition, including asphaltenes, resins, and • The material should be introduced via a large burner polycyclic aromatic hydrocarbons. The water in the sludge placed on the top or in the center of the burner pipe contains heavy metals and other chemical elements such (not on the bottom). as sodium, calcium, magnesium, and potassium. Spent catalysts are granular solids with a chemical composition that includes a matrix of silica or alumina impregnated Increasing the Use of Alternative Fuels at Cement Plants: International Best Practice 49 with nickel, cobalt, platinum, molybdenum, or other heavy • Wood, including the production of furniture metals. Solids generated in pollution control systems contain • Paper and cardboard organic material, such as hydrocarbons, ash, and other particulate matter. • Metallic equipment • Automotive Recycling and reuse are the most common solutions for the disposal of solid waste in this sector. The oil and gas • Food exploration and production segment recycled about 70 • Rubber and plastic percent of the hazardous waste it generated in 2010. • Electrical and electronics equipment Incineration and biotechnological methods also are employed. Waste disposal in landfills has been avoided over • Shoe and textile industries. the years. Management of this waste stream could be handled directly 4.4.1 NON-HAZARDOUS INDUSTRIAL WASTE by the producer—including waste collection but also MARKET FOR NON-HAZARDOUS INDUSTRIAL WASTE operations such as sorting, recycling, and on-site recovery (including the production of steam or, less frequently, power) There are two main types of non-hazardous industrial waste: (see Figure 34). • Production waste, such as the raw material remainder The production of waste made of a mono-product often is and off-spec products managed directly between the producer and the collector- • Packaging waste from the containers and wrappings of recycler, mainly in the case of large production. The raw material and equipment (for example, from factories collection is managed by a collecting company with highly and administrative buildings). skilled professionals in waste/raw material sorting to European statistics show that the main industries producing deliver the qualities compliant with the specifications of the non-hazardous industrial waste are: recycling industry (for example, paper, cardboard, plastics). The company then finely sorts and delivers the waste in Figure 34: Schematic of the Distribution in the Collection and Treatment Modes in France in 2008 Before the Reduction of Landfilling Private collection system Collection by producer Included in municipal Mono-Product Selective Mixed solid waste collecton 22% 40% 8% 24% 6% Sorting 2.9 MT Incineration 8% Energy recovery on-site Material recovery Landfilling 9% 152% 30% Source: Sofies AS. 50 Four Case Studies of Alternative Fuel Use compressed bales, which are often exported. China has been • As a unique provider of service: In the case of large- the main destination of this waste, but the development scale waste production, the cement plant can contract of domestic recycling industries in many countries is directly with the waste producer, creating a direct link reintroducing this waste source in the country for both industry to industry. recycling and co-processing. • After a sorting operation: This scheme is comparable to that used in the case of municipal solid waste. For smaller amounts of waste, collection often is done via a rented bin that is used for receiving the non-hazardous • As a service to the recycling industry: The recycling industrial waste produced by a factory, for example. In the industry is receiving used product that contains case of several factories, several bins are located at the plant. pollutants (such as from the paper industry), and the The quality of the waste collected in a bin could be very process requires extracting those pollutants that could poor, as no sorting is done and the bins might be exposed be of sufficient quality for co-processing (see Figure 35). to the elements. A sorting operation is always required to PREPARING ALTERNATIVE FUELS FROM extract the burnable fraction. NON-HAZARDOUS INDUSTRIAL WASTE: THE CASE OF PAPER In the case of small and medium enterprises, the collection of non-hazardous industrial waste often is included in the Preparing RDF from non-hazardous industrial waste is municipal waste collection service. similar to the process of preparing RDF from municipal solid waste. One useful example is the cooperation of the cement POSITIONING OF CEMENT PLANTS IN THE industry with another industrial sector: the paper industry. NON-HAZARDOUS INDUSTRIAL WASTE MARKET There are several options for positioning cement plant Producing recycled paper creates waste at the initial stage co-processing in this market: of the paper recycling process—when the paper fiber is extracted from the used paper. The bales of used paper are Figure 35: Potential Positioning of Co-processing in Management of the Non-hazardous Industrial Waste Stream Private collection system Collection by producer Included in municipal Mono-Product Selective Mixed solid waste collecton 22% 40% 8% 24% 6% Sorting 2.9 MT Co-processing Co-processing Incineration 8% Energy recovery Co-processing on-site Material recovery Landfilling 9% 152% 30% Source: Sofies AS. Increasing the Use of Alternative Fuels at Cement Plants: International Best Practice 51 mixed with water in a pulper. Any “impurities” mixed in • The quality of packaging waste from industry is much with the paper in the bales (for example, plastics, textiles, better (in terms of calorific value, moisture, chlorine) inerts) are extracted by flotation or settling/sedimentation than the packaging extracted from municipal waste, and and become waste. • The process used to produce the RDF, even the quality for the main burner, is often simpler and produces less waste These impurities can represent 5 to 10 percent of the input compared to RDF produced from municipal solid waste. when saturated with water (40 percent). As produced, the calorific value is relatively low (8 to 10 gigajoules per ton), In countries where RDF for cement plants is produced from but it can reach 25 gigajoules per ton after drying and non-hazardous industrial waste, it is possible to achieve a extraction of the inert fraction. calorific value above 20 gigajoules per ton, and in some cases 23 to 25 gigajoules per ton, a quality that is directly usable A shredding line with an air separator and overband for the main burner. conveyer will produce the RDF with the adapted particle size. A thermal dryer fed with waste heat from the kiln will Considering the homogeneity of non-hazardous industrial produce the quality required for the main burner. waste, the quality will be much more constant than for municipal solid waste because the RDF is produced out of The waste from the paper industry also could be mixed with mono-product waste. waste from plastics recycling to guarantee a high calorific value (see Figure 36). This waste segment should be considered a priority, given RDF QUALITY the high potential of use in co-processing and the small quantities available in the market. The process used to produce RDF out of non-hazardous industrial waste is comparable to that described for The industry will be more sensitive to the reduction of municipal solid waste, with two main differences: landfilling, and, in a country where the incineration capacity is very limited, co-processing is an operational option for the entire industrial sector. Figure 36: Schematic of RDF Production from Paper Waste to Cement Plant Paper industry Used paper and Pulper Production of cardboard in bales recycled paper Pre-processing Plastic from Pre-shredding, recycling industry air classifier, shredder Calciner Co-processing Thermal dryer Main burner Source: Sofies AS. 52 Four Case Studies of Alternative Fuel Use Cooperation with recycling activities is important to reduce requiring highly skilled technicians to manage processes, the potential perception of co-processing being a competitor. chemical risks, and health risks. Co-processing the waste from recycling activities supports this activity and increases the recovery ratio of a country. In some countries, preparation is carried out by waste management companies dedicated to hazardous waste, 4.4.2 BLENDING OF HAZARDOUS INDUSTRIAL with whom the cement companies sign mid- to long-term WASTE contracts. However, relations between these companies HAZARDOUS INDUSTRIAL WASTE FOR THE can turn to conflict when the waste management company BLENDING MARKET operates its own treatment solutions using incinerators, with In most countries, hazardous industrial waste was the co-processing being considered as a buffer (or secondhand first waste stream available for waste treatment. In light solution) to guarantee full use of its equipment. of its heterogeneity and the small batch quantities made available by some producers, the concept of pretreatment In some countries, cement companies have opted to create was introduced to produce an alternative fuel acceptable for joint ventures with waste management companies or burning in cement kilns. subsidiaries dedicated to the management of hazardous industrial waste in order to have greater control over The first pretreatment processes were very simple and were sourcing and the market. oriented along two main directions: Given the specificities of the waste, some cement companies • Production of a liquid alternative fuel also have opted to subcontract operations inside the cement plant, giving control over waste receiving and handling to • Production of a solid alternative fuel. these dedicated companies. The pretreatment facility has to take into consideration the PREPARATION OF ALTERNATIVE FUEL THROUGH A chemical, physical (liquid, sludge, or solid), and conditioning BLENDING OPERATION (bulk and drums) heterogeneities. There are two blending options for the hazardous waste: one Hazardous industrial waste is generated by all industries producing a liquid alternative fuel (with high viscosity) and that process, produce, or use chemicals or oils. The main the other producing a solid alternative fuel. producers are the following industries or activities: Preparation of Liquid Alternative Fuel, or Fluidification • Chemical, pharmaceutical, and cosmetology This concept is based on a dilution of the pasty and small portion of solid waste with liquid wastes (spent solvents or • Oil (both extraction and refining) oily wastes), with the blending occurring in a high-speed • Paint mixer (see Figure 37). The blend is screened to extract the • Automotive remaining solid fraction. Some facilities also are including a shredder for drums to avoid the need for emptying them; • Steel and metallurgic the shredded metal is extracted using a magnetic separator • Industrial cleaning. before introduction in the high-speed mixer. The blend must be stored in a vertical silo with continuous stirring. POSITIONING OF CEMENT PLANTS IN THE BLENDING The maximum quantity of solid (pasty) waste that could MARKET be introduced is below 50 percent, with an average of 30 Based on the nature of the waste (heterogeneity and percent. The remaining waste from the process must be variability of the composition), a preparation step is disposed of in a specific incinerator at a high cost. mandatory. Given the chemical specificities of the waste, however, this step resembles more closely a chemical activity, Increasing the Use of Alternative Fuels at Cement Plants: International Best Practice 53 Figure 37: Example of Flowsheet for Liquid Alternative Fuel Preparation Source: Sofies AS. Preparation of Solid Alternative Fuel in foam form have been identified, but they have lower efficiency compared to sawdust. The ratio of sawdust is The basic concept is the mixing of solid and pasty wastes often about 40 percent, making this process relatively costly. with an adsorbent to produce a solid alternative fuel (see Figure 39). The mixing is realized in several steps: coarse The facility must be located in a closed building to avoid blending in a pit and one or two steps of mixing within the dispersion of volatile organic compounds. The collected screens, extracting the foreign bodies. To achieve a quality air must be treated; bio-filtering and catalytic burning have that is compliant with the main burner specifications, a shown good efficiencies. shredder is mandatory. The most popular adsorbent is sawdust, but with the increase in the cost of sawdust, operators have been looking for alternatives; some plastics Figure 38: Example of Facilities for Liquid Alternative Fuel Preparation Source: Sofies AS. 54 Four Case Studies of Alternative Fuel Use Figure 39: Example of Flowsheet for Solid Alternative Fuel Preparation Source: Sofies AS. ALTERNATIVE FUEL QUALITY The alternative fuel specifications are set in the contract between the preparation step and the cement plant. For the liquid alternative fuel, the calorific value depends mainly on the quality of the solvents; it is often above 15 gigajoules per ton, with 20 gigajoules per ton being possible in the best cases. For the solid alternative fuel, the calorific value depends on the moisture content of the sawdust (furniture sawdust is one of the driest) and the moisture of the wastes. A calorific value between 12 and 15 gigajoules per ton is achievable. Increasing the Use of Alternative Fuels at Cement Plants: International Best Practice 55 APPENDIX 1 DETAILED INFORMATION BY ALTERNATIVE FUEL TYPE 1. Hazardous Spent Solvents Origin Composition The hazardous solvents available in the waste market A wide variety of hazardous solvents are available in the waste originate from: market, ranging from the most expensive to the most common. • Chemical and pharmaceutical processes They include hydrocarbon- and alcohol-based solvents as well as solvents that are mixed with water or that are polluted with • Manufacturing of paint and other building materials, as well as chlorine and heavy metals to varying degrees. These solvents could the use of paint in the automotive industry, furniture production, exist in a liquid or a pasty phase, with the latter being generated and elsewhere. mainly from internal or external recycling activities. • Cleaning activities in metals workshops or garages The standard composition of the waste solvents that are available • Recycling activities. for energy recovery is: The production of spent solvents in the painting sector is • LCV: 20 to 28 gigajoules per ton (alcoholic solvents are below decreasing as solvents are replaced by water. these values) At the same time, stricter regulation of volatile organic compounds • Chlorine: 0% 2%; average 0.6% to 1% in most factories could increase slightly the quantity of spent • Moisture content: 0% to 25% solvents. However, this increase is mitigated by the replacement of solvents with water to avoid complex management of volatile • Metals: 1,000 to 5,000 parts per million organic compounds. Traditional Destination Supply Chains Provided that strict regulations are implemented for managing Because spent solvents are classified as hazardous waste volatile organic compounds and preventing water discharge, the and can be highly flammable, transport must be managed by typical destinations for spent solvents are: specialized companies using specially adapted tanker trucks. • Recycling The transport company must be notified about the specific risks linked to each component of the waste mixture. • This could occur within factories in the case of large-scale production or expensive solvents, or in specialized facilities. Small-to-medium volumes of spent solvents also could be stored in drums, with the nature of the stored solvents and the risk • Recycling activities produce distillation residues with high information written clearly on the drum casing. Collecting this concentrations of chlorine, metals, and sediments. waste could be done using trailers or by direct transfer in tanker • Thermal recovery trucks equipped with vacuum pumps. With the latter option, • This could occur in specialized incinerators or in cement plants the risk of reaction between two different qualities must be operating with a hazardous materials permit. managed as the solvent is pumped, meaning that this operation • Given the high calorific value of spent solvents, they are used must be handled by workers who are trained in responding in incinerators as a valuable energy source for burning other to potential risks (for example, heating, boiling, explosion, waste material. production of solid phases). 56 Appendix 1: Detailed Information by Alternative Fuel Type Preprocessing Environmental Implications The preprocessing operations for spent solvents could be: The equipment and operations must be compliant with • Transfer of wastes from drums to tanks environmental regulations related to solvent management. • Blending Spent solvents must be stored in steel tanks that are compatible with solvent specifications. The tanks must be located in a • Phase separation. retention basin to prevent spillage to the soil or water. The The main risks associated with the two first operations are: pumping system must be located in a place that facilitates the • Chemical reaction producing heat, gas, or explosion collection of leakage. • Solidification or creation of a solid phase (for example, by mixing The storage zone must be equipped with a fire protection system paint with alcohol) that is adapted to the stored solvents. • Mixing of chlorinated solvents with non-chlorinated ones, The solvents must be handled as much as possible in a producing a chlorinated product that is not compatible with confined unit or factory to avoid the release of volatile organic recovery in cement kilns. compounds to the atmosphere and the exposure of the workers These operations must be handled in a dedicated facility that has and stakeholders to these compounds. Depending on their a permit for hazardous waste. The workers must be trained in the specifications, the spent solvents could be managed in tanks risks. A lab to manage the quality and risk associated with blending with a nitrogen atmosphere or capping of the gas. The potential must be controlled by a chemist. dispersion of vapors must be taken into consideration during the loading and unloading of trucks. Whatever the operation performed, the wastes maintain their “hazardous” classification following preprocessing, even in the case For drums, it is recommended that handling be managed in a of blending hazardous with non-hazardous wastes. closed building with capping and treatment of the volatile organic compounds. Workers must wear personal protective equipment that is adapted to potential exposure. Carbon Dioxide Mitigation Barriers Spent solvents originate from hydrocarbons and have no impact on • Quantity of spent solvents with characteristics compatible with carbon dioxide reduction. the cement process • National regulations must ban discharge into the natural environment (for example, via sewers, sewage plants, rivers) CAPEX and OPEX • Mixing of chlorinated with non-chlorinated solvents must be avoided Facility requirements include: • Cement plants must apply for a hazardous waste permit, • Unloading zone for trucks on concrete, with collection of spillage a procedure that could be complex and could raise strong • Tanks in a retention basin opposition from stakeholders • Preference for vertical tanks with conical bottoms • Competition with incinerators, which could buy high-quality • Small tanks (10 to 25 cubic meters) in preprocessing facilities spent solvents and drive up the price to levels that are • Large tanks (100 to 500 cubic meters) in cement plants non-competitive with traditional fossil fuels in a cement plant. • Two stirring technologies: one vertical mechanic and one • Prioritization of recycling recirculation loop • However, recycling activities still need a recipient for the • Separate pumping systems for unloading, stirring, and injection distillation residues, which could lead to natural cooperation between recycling and co-processing. • Filtration by auto-cleaning system, or static filtration in the unloading line • Technical barriers • Electrical devices designed with consideration of solvent flash • Chlorine: traditional chlorinated solvents are not acceptable points (ATEX rules) • Flash point: a wide range of flash points is possible, with costly • CAPEX: €5 million to €10 million consequences for capital expenditures (CAPEX) • OPEX: €10 to €20 per ton • Homogeneity: risk of phase separation in storage, with huge variation in calorific value at the burner Increasing the Use of Alternative Fuels at Cement Plants: International Best Practice 57 2. Waste Oil and Industrial Oil Origin Composition Waste oil originates from any engine that requires lubrication (for The standard composition of the waste oil available for energy example, car, truck, bus, mining machine/ truck, diesel locomotive, recovery is: power generator, lawn maintenance equipment). Some industrial • LCV: 25 to 35 gigajoules per ton processes also generate used oil, such as steel plants (liquid), tire • Chlorine: 0% to 1% (related to the potential presence of cleaning manufacturing, food oil production, and others. solvents) • Moisture content: 0% to 20% (linked to storage conditions) • Metals: <1,000 parts per million Special attention should be given to potential PCB (polychlorinated biphenyl) pollution and to solvents with a low flash point. The composition of industrial oil could vary significantly. Blending of industrial oil with used engine oil must be checked in a lab prior to occurring in the cement plant. Traditional Destination Supply Chains The top two typical destinations for waste oil are: Collection of waste oil is a key issue. Garages typically store their • Recycling: producing recycled oil out of used oil used oil in small tanks and therefore need responsive and frequent collection. Often, the collection is performed by small trucks (5 to • Recycling could be limited if the cost of producing recycled oil 7 cubic meter volume) that ship the waste to a transit platform exceeds the cost of new oil. Some older recycling processes, before it is delivered to its final destination. such as the sulfuric process, produce waste (sulfuric tar) that is very difficult to dispose of. • Recycling is becoming more profitable in facilities with significant capacity (>100,000 tons per year) • Energy recovery: cement plants are the top destination when the used oil is classified as waste. Preprocessing Environmental Implications Waste preparation occurs at the transit platform, including: The equipment and operations must be compliant with • Blending of different collection sources environmental regulations related to hydrocarbon management. • Separation of water via decantation, either naturally or The tanks must be located in a retention basin to prevent spillage accelerated by surfactants to the soil or water. The pumping system must be located in a place that facilitates the collection of leakage (usually in the retention bin • Emptying of drums or on concrete soil with drainage). Because garages generally do not have the means to control waste The storage zone must be equipped with a fire protection system quality, this control must take place at the transit platform. For adapted to hydrocarbons and must consider the potential presence example, PCBs could be detected at this stage. The storage capacity of solvents with low flash points. of these facilities comprises small tanks (10 to 25 cubic meters) to avoid the diffusion of pollution within bigger waste volumes and to perform the appropriate blending. 58 Appendix 1: Detailed Information by Alternative Fuel Type Carbon Dioxide Mitigation Barriers Used oil is composed of hydrocarbons and has 0 percent biomass. • Mobilizing the market at a reasonable price • A good waste collection system with efficient quality control is required to mobilize this resource. Garages will give their used oil to a formal collection service if it is free. CAPEX and OPEX • Clear regulation Facility requirements for waste oil include: • The illegal burning of used oil in garages as a heating source or mixed with other hydrocarbons to produce fuel for engines • Unloading zone for trucks on concrete with collection of spillage is the largest competitive use when regulation is not clear and • Tanks in a retention basin does not classify used oil as waste. • Preference for vertical tanks with conical bottoms • Regulation also must control the discharge of used oil into • Small tanks (10 to 25 cubic meters) in preprocessing facilities sewers, which often occurs when people change the oil in their • Large tanks (100 to 500 cubic meters) in cement plants vehicles themselves. One liter of oil can contaminate more than 1 million liters of water! • Tanks that formerly were used for fuel oil in cement plants can be reused • Fair competition with recycling, based on market rules and not artificial competition • Stirring by a recirculation loop • Fair competition with other energy recovery process (such as • In case of vertical possibility, extract the water waste burning), meaning that the other processes must be • Pumping system for unloading, stirring, and injection subjected to the same environmental rules • Filtration by auto-cleaning system, or static filtration on the • Cement plants must apply for a waste permit (since used oil is unloading line considered waste), a procedure that could be complex and could • Electrical devices raise strong opposition from stakeholders. • CAPEX: €1 million to €3 million (could be reduced in cases of reuse • Technical barriers of old tanks) • Chlorine and PCBs, since the engine oil could be mixed with • OPEX: €5 to €10 per ton used oil from electrical equipment (for example, transformers, condensers) • Homogeneity: risk of water separation in storage. Increasing the Use of Alternative Fuels at Cement Plants: International Best Practice 59 3. Wastewater Origin Composition The wastewater available in the waste market originates from: Wastewater is mainly water that is polluted with chemicals, • Chemical and pharmaceutical processes surfactants, solvents, or oil. • Metals workshops The standard composition available for energy recovery is: • Airport and road de-icing activities • LCV: 0 gigajoules per ton • Cleaning activities in industries. • Chlorine: <0.5% • Moisture content: >80% • Metals: 1,000 to 2,000 parts per million Traditional Destination Supply Chains The typical destinations for wastewater are: Because wastewater is classified as hazardous waste and can • Sewage plants (when the water is compatible with biological be highly flammable, transport must be managed by specialized treatment) companies with specially adapted tanker tanks. The transport company must be notified about the specific risks linked to each • Physico-chemical treatment (to separate water and pollutants component of the mixture, even if the concentration of pollutants such as oil and solvents) is low. • Incineration (direct, or following a concentrating process). Preprocessing Environmental Implications The preprocessing operations for wastewater could be: The equipment and operations must be compliant with • Blending environmental regulations related to solvent management. • Phase separation. The wastewater must be stored in steel tanks that are compatible with its potentially alkaline or acidic characteristics. The tanks The main risks associated with these operations are: must be located in a retention basin to prevent spillage to the soil • Chemical reaction producing heat, gas, or explosion or water. The pumping system must be located in a place that • Solidification or creation of a solid phase (for example, by mixing facilitates the collection of leakage. paint solvents with alcohol) In case of the potential presence of solvents, the storage zone must • Mixing of chlorinated solvents with non-chlorinated solvents, be equipped with a fire protection system. producing a chlorinated solvent that is not compatible with For drums, it is recommended that their handling occur in a recovery in a cement kiln. closed building with capping and treatment of the volatile organic These operations must be handled in a dedicated facility that has compounds. Workers must wear personal protective equipment a permit for hazardous waste. The workers must be trained in adapted to a potential exposure. the risks. A lab that manages the quality and risks associated with blending must be controlled by a chemist. Whatever the operation performed, the preprocessed waste is still classified as ”hazardous” following preprocessing, even when hazardous wastes are blended with non-hazardous wastes. 60 Appendix 1: Detailed Information by Alternative Fuel Type Carbon Dioxide Mitigation Barriers Wastewater has no impact on carbon dioxide, but it decreases the • Regulations must set strict rules for the discharge of wastewater production of nitrogen oxide. in rivers. • A leading impact results from the introduction of water, which produces high-temperature steam inside the cement kiln. The CAPEX and OPEX extracting fan is designed to handle a certain quantity of steam at the kiln’s maximal load; however, this capacity could be reached Facility requirements include: with new injection of water. To mitigate this impact, it is possible • Unloading zone for trucks on concrete, with collection of spillage to inject the water into the clinker cooler, a stage at which the • Tanks in retention basin or double-envelope tanks temperature is compliant with regulations. • Preference for vertical tanks with conical bottoms • Cement plants must apply for a permit for hazardous waste, a procedure that could be complex and could raise strong • Small tanks (10 to 25 cubic meters) in preprocessing facilities opposition from stakeholders. • Large tanks (100 to 500 cubic meters) in cement plants • Technical barriers • Stirring by ic stirrer and a recirculation loop • Chlorine: potential presence of salts • Separate pumping systems for unloading, stirring, and injection • Flash point: potential presence of solvent traces • Filtration by auto-cleaning system, or static filtration on the • Homogeneity of the calorific value of waste: potential phase unloading line separation of solvents • Electrical devices designed with consideration of solvent flash points (ATEX rules) • CAPEX: €1 million to €3 million, depending on the flash point and installation capacity • OPEX: €5 to €10 per ton. Increasing the Use of Alternative Fuels at Cement Plants: International Best Practice 61 4. Used Tires and Rubber Wastes Origin Composition Used tires originate from the production of tires and the The standard composition of used tires available for energy replacement of tires from vehicles such as cars, trucks, and recovery is: buses. Other rubber waste originates from conveyor belts, shoe • LCV: 26 to 28 gigajoules per ton (for truck tires, 23 to 26 gigajoules production, and many other sources. per ton) Used tires are stored at garages, tire retailers, and large fleet depots • Chlorine: <0.1% for cars, trucks, and buses. • Sulfur: around 1.5% In many countries, historical disposal has created large stockpiles of • Moisture content: 0%, but possible accumulation of water inside used tires, without formal ownership. the tire during storage In countries where extended producer responsibility is • Metals: iron: 15% to 20%, zinc: 1% to 2%, others: 1,000 to 4,000 implemented, tire manufacturers are in charge of the collection parts per million and treatment of used tires. Often, these manufacturers create an entity to which they subcontract the collection and disposal management of used tires. Traditional Destination Supply Chains The typical destinations for used tires and rubber wastes are: Tire collection is the main management issue. Used tires are • Retreading dispersed widely in small quantities and are stored in factories with limited storage capacity, meaning that used tires need to be moved • In most developed countries, the national retreading ratio is out frequently. close to 10 percent Solutions for organizing collection include: • In developing countries, the ratio is very low, in part because the tires are used until the very end of their lives, making retreading • A specific network of collectors that could be registered by tire almost impossible manufacturers. • Material recovery, which could take different forms: • The distribution network for new tires also could be used for used tire collection. • Use in civil works in the form of bales, or direct use to reinforce road banks or dams • The distribution network for cement could be used, with the same trailers that transport bagged cement being used for tire • Production of granules used to produce rubber equipment, transport. athletic field surfaces, and other items. • The production of granules generates waste such as tire cords and steel. Tire cords are an interesting alternative fuel for cement plants, with high calorific value. • Energy recovery • Cement plants are a natural destination of used tires (shredded or not), as they provide an advantage from the recycling of the steel structure combined with energy recovery • Some trials have been done in steel plants, but with limited quantities because the process is very sensitive to the presence of the metallic structure of the tires as well as some metal traces. 62 Appendix 1: Detailed Information by Alternative Fuel Type Preprocessing Environmental Implications The preprocessing of used tires is limited to shredding operations. The main environmental risk is related to storage of used tires, with Dedicated shredders must be used to manage the combined two aspects: shredding of steel with rubber. • The accumulation of water in tire envelopes provides a breeding The shredding of large tires is more complex and occurs in several ground for mosquitoes steps, including first extracting the metallic structure or precutting • Handling procedures for tires (mainly truck tires) must address the tire into large pieces using a specialized machine (for example, ergonomic aspects to prevent back pain. a crocodile cutter). The equipment and operations must be compliant with environmental regulations related to used tires. Fire management in tire storage depots is a unique issue and requires a specific approach: • Creation of several smaller piles rather than one big pile to limit the risk of a large fire, since fire extinction could be a long process. • Storage of sand or another high-density mineral close to the tire piles to block fire and as part of the prevention plan • Taking enough time to fully extinguish a fire. Carbon Dioxide Mitigation Barriers Because the rubber typically used in tires comes partially from • Cement plants must apply for a permit for waste (since used tires natural sources, the biomass content is between 25 and 35 percent. are considered waste), a procedure that could be complex and could raise strong opposition from stakeholders. • Organizing tire collection is key and could be expensive. CAPEX and OPEX • Strict bans on the landfilling of used tires drive the need to find an organized solution. For shredding operations: • In several countries, extended producer responsibility has proven • Shredding line, depending on the size required after shredding its efficiency in creating an efficient collection operation, making • CAPEX: €1 million (30,000 to 50,000 tons) plus potential tire producers responsible for addressing waste management, infrastructure costs (for example, civil works, roads, power supply) with the cost passed on to purchasers of new tires through a • OPEX: €15 to €40 per ton (from 25 to 100 millimeters) small eco-tax. In the cement plant, facility requirements include: • Competition with material recovery • For injection in the pre-calciner or backend: • Use of the tires for land stabilization is very close to landfilling • Storage zone for used tires, with fire management system and, in some cases, becomes a means to bypass the landfill ban. • Transporting the tire to the injection point by lift, hock elevator, • Use of the tires in civil works must bring a real advantage conveyor belt and must be framed and classified to avoid the uncontrolled dispersion of tires in the environment. • Dosing system • The production of granules is economically more attractive than • Double- or triple-flap airlock to feed the tire in co-processing because of the good market price for granules. In • For injection of shredded material: Europe, investment in large granulating capacities over the last • Hall for receiving shredded tires two years created a production overcapacity that led to a direct • Tank for storage decline in the granule price, leading some companies to deliver the granules to cement plants. • Conveyor • Competition with other energy recovery processes • Injection system • The use of tires in steel plants is limited. • CAPEX: €1 million to €3 million • Some power plants are using used tires, but facility investments • OPEX: €5 to €10 per ton are required for feeding, burning, and emission depollution. • Technical barriers • Management of whole tires: injection and impact on the process • Sulfur: limited impact Increasing the Use of Alternative Fuels at Cement Plants: International Best Practice 63 5. Industrial Sludge Origin Composition Industrial sludge originates from the treatment of all of the effluent The composition of sewage sludge depends on the source and the of a plant, including process rejects, rainwater collection, and other preparation process. effluent. For oil sludge, the composition is as follows: In the production plant, different options for preparation can be • LCV: 5 to 15 gigajoules per ton implemented: • Chlorine: 0% to 0.5% • Reception in tanks or lagoons to blend the different sources and • Moisture content: 1,000 to 3,000 parts per million manage the quality control before discharging into a sewer, a combined sewage plant, or a river. • Metals: <1,000 parts per million • The tank or lagoon must be cleaned on a regular basis (monthly, • Ash: 10% to 50% annual), producing sludge that needs to be disposed of. • Simple decantation with or without oil separator • Sludge produced in small quantities is usually pumped by a vacuum cleaning truck. • Biological or physico-chemical sewage plant • Different natures of sludge are produced: physico-chemical or biological • After biological treatment, the sludge could be dried by mechanical treatment (centrifuge or filter press) or a thermal process. These operations can be performed in an external collection facility that will produce the sludge. The cleaning of tanks also produces sludge. The remediation of old lagoons or storage, either orphaned or with an identified owner, is also a source of sludge. In a similar category, dredge sludge originates from the cleaning of canals or sewers. This analysis focuses specifically on the oil sludge produced in refineries or during oil extraction. Huge quantities are produced worldwide, and cement plants are one of the main destinations for this sludge. Traditional Destination Supply Chains A wide range of destinations exist, considering the potential Traditional trucks are used to transport the sludge. In the case of variations in quality. Typical destinations are: simple trailers, the risk of spillage must be managed. • Land spreading • This solution could be used for inorganic sludge, presenting real agronomic value coming from inorganic chemistry. • The presence of pollutants, even in small concentrations, is a limiting factor on this use. • Landfilling • Landfilling of sludge is applicable for sludge with low moisture content. • Water present in the sludge could easily leach or give thixotropic properties to the sludge, disrupting landfill operations (production of leachate and destabilization of the waste layers). • Incineration • Within an incinerator located on the sewage plant premises (for large-scale production) • Within a external incinerator managed by a waste management company • In the case of remediation of old lagoons, the pretreated sludge could be landfilled on-site after preparation (mixing with lime or sawdust). 64 Appendix 1: Detailed Information by Alternative Fuel Type Preprocessing Environmental Implications For producing alternative fuel for cement plants, there are several The equipment and operations must be compliant with preprocessing options: environmental regulations related to sludge, in some cases • Mechanical drying in the sewage plant hazardous sludge. • Thermal drying (in the sewage plant or in the cement plant using The main risks associated with industrial sludge are: waste heat from the kiln) • Smell (mainly in the case of biological sludge) • Mixing with adsorbents to produce a solid alternative fuel • Dust (in the case of very dry sludge) • For organic sludge, the adsorbent could be sawdust or other • Chemical hazard linked to the presence of chemical or hazardous waste with high adsorption properties. wastes in the sludge • The adsorbent could be lime or limestone, used widely for oil • Biological hazard, which can be limited if workers wear personal sludge. protective equipment adapted to a potential exposure. • The cost of the adsorbent could make preparation expensive (as in the case of sawdust) compared to the benefit of handling solid wastes. Carbon Dioxide Mitigation Barriers The biomass content could be very variable. For oil sludge, it is 0%. • Cement plants must apply for a permit for waste (hazardous, in some cases), a procedure that could be complex and could raise strong opposition from stakeholders. • Competition with land spreading CAPEX and OPEX • Clear regulation regarding landfilling must be issued, with regular controls. In the cement plant, for the injection of pasty sludge, the facility requirements include: • Cement plants offer a service nearly year-round, compared to land spreading that has high seasonality. • Unloading pits • Cement plants are more flexible than land spreading because • Several pits to enable blending they can receive hazardous and non-hazardous sludge whatever • One pit with mechanical extraction at the bottom to feed the the physical nature. pump below this storage • Competition with incineration. Some waste producers operate • Feeding hopper incineration capacity, but they need to find a solution for the ash. • Transfer from pit to hopper by crane • The environmental regulation applied to these incinerators must • Concrete pump be compliant with regulation on waste incineration. • Traditional concrete pump with some adaptation to oil handling • Competition with on-site treatment • High-pressure pipe leading to the injection line • Rules for the on-site landfilling of prepared must be clearly • Special burner (atomization) defined. • CAPEX: €1 million to €3 million • Technical barriers to co-processing • OPEX: €10 to €20 per ton, depending upon the use of a crane • Variability of the calorific value and/or the ash content: managing the impact on the process and on the raw mix In the cement plant, for the injection of dry sludge, the facility composition requirements include: • Variability of the viscosity. • Unloading zone for truck • Pneumatic delivery, or • Delivery in an hopper at the bottom of the silo and feeding by mechanical conveyor • Vertical silo with explosion protection; in some cases the silo is equipped with an inertization system (N2 or other gas) • Extraction • Pneumatic injection • CAPEX: €1 million • OPEX: €5 to €10 per ton Increasing the Use of Alternative Fuels at Cement Plants: International Best Practice 65 6. Non-hazardous Industrial Waste Origin Composition This waste can originate from several different sources: The composition of industrial packaging waste is similar to • Packaging waste that of household packaging waste. The composition of other non-hazardous waste is linked to the process generating the waste. • Process waste, such as pulper waste in the paper recycling industry The standard composition of non-hazardous industrial waste available for energy recovery is: • Off-spec products and product losses. • LCV: 15 to 25 gigajoules per ton, depending on the composition (paper vs. plastics) • Chlorine: 0% to 2% • Moisture content: 10% to 20% • Metals: 1,000 to 3,000 parts per million The standard composition for pulper waste available for energy recovery is: • LCV: 6 to 12 gigajoules per ton (20 to 25 gigajoules per ton after drying) • Chlorine: 0.5% wet • Moisture content: 40% to 60% • Metals: <1,000 parts per million This waste segment is a source for producing solid recovered fuel (SRF)/RDF (see section on CAPEX/OPEX) • Quality required for main burner • Quality required for pre-calciner • Quality require for pre-combustion chamber. Traditional Destination Supply Chains The typical destinations for non-hazardous industrial waste are: There are different options for organizing the collection of • Recycling, a leading destination mainly when this waste is a non-hazardous industrial waste: mono-product • Selective collection (more or less complex) to extract the recyclable • Incineration (with or without energy recovery), which could fraction at the source. This could be followed by sorting of the be carried out internally and/or in an external collection facility materials, mainly within the recycling management company. including municipal waste incinerators • Universal collection, with use of a transfer station • Landfilling, which is an important destination in many countries • For small and medium enterprises, industrial wastes are mixed in and could occur on the premises of the waste producer or a designated bin. Recycling is more difficult in this case, and the externally (municipal or not). waste is considered to be normal municipal waste and follows the standard chain of treatment.. Preprocessing Environmental Implications For producing alternative fuel for cement plants, there are several The equipment and operations must be compliant with preprocessing options: environmental regulations related to municipal waste. • Sorting operations The main risks linked to the SRF/RDF are the same as the risks • Drying of the waste identified for SRF/RDF produced from municipal waste: These operations must be handled in a dedicated facility that has a • Fire provoked by a shredding operation, by self-combustion permit for waste management. The workers must be trained in the (when organic material is stored too long), and by other means risks. A quality management system must be implemented, with • Solution: fire detection equipment such as thermal cameras and subcontracting (or not) to an external lab. adapted extinguishing equipment as well as frequent training of The mixing of hazardous waste, including household hazardous workers waste, must be prohibited. • Dust explosion: given the fluffy aspect of the waste and the organic fraction of the dust, the accumulation of dust in factories Carbon Dioxide Mitigation and storage facilities could provoke an explosion SRF/RDF produced from non-hazardous wastes contains a • Solution: frequent cleaning of the halls and superstructure of biomass fraction made of wood, paper, and organic wastes. buildings. Depending on the country, the biomass fraction is between 25 and 50 percent. 66 Appendix 1: Detailed Information by Alternative Fuel Type CAPEX/OPEX Barriers The facility requirements include: • Cement plants must apply for a permit for waste (since SRF/ • Preprocessing shredding line RDF is considered waste), a procedure that could be complex and could raise strong opposition from stakeholders • Shredding line: the design depends on the targeted granulometry • Competition with landfilling • A one-step shredding operation could be performed to achieve the quality required for the precalciner (50 to 80 millimeters). For • SRF/RDF production must be competitive compared to a typical design, requirements include: landfilling. In some countries, the landfill gate fee is too low to cover the cost of RDF/SRF preparation. • First-step shredding • Regulation must limit access to landfilling (through either • Wind-shifter or ballistic separator technical restriction or taxation) and place a clear priority on • Recirculation of the larger pieces to the shredder recycling and recovery operations. • Magnetic separator • Competition with incinerators • CAPEX: €0.5 million to €1 million plus civil works and utilities • Because an incinerator as high fixed costs, it must operate at full • OPEX: €15 to €25 per ton capacity. The design must be strictly adapted to the needs of the • Two-step shredding is required to achieve the quality required for waste to be incinerated. the main burner (20 to 35 millimeters) • Regulation can give clear priority to the most efficient use of the • First-step shredding waste (in the context of optimizing resource management), to energy efficiency, and to phasing out energy-intensive industrial • Wind-shifter equipment. • Second-step shredding with two shredders in parallel • Cement plants operate a high-energy process and often • Wind-shifter approach large-scale waste utilization. This investment is • Magnetic separator minimal compared to building a new incinerator. • CAPEX: €1 million to €2 million plus civil works and utilities • Bans on thermal use of this waste • OPEX: €20 to €40 per ton • Co-processing (generally speaking, any thermal use) could be In the cement plant, the receiving facility could range from very seen as competing with recycling, providing an easy and cheap simple to more complex: solution for waste generators. • For small capacity (1 to 5 tons per hour): • However, recycling activities need a destination for their own recycling wastes, which could lead to natural cooperation • A simple docking station for two to three trucks is enough, between recycling and co-processing. provided the logistics are adapted (for example, proximity of the shredder, possibility of delivery over the weekend, low cost for • The profitability of recycling is linked to the market price of the immobilization of delivery trucks). recycled materials, and the alternative fuel also must be cheaper than the fossil fuel. Sustainable recycling must be profitable. • Storage is in a silo with protection from dust explosion. • Technical barriers: • Transport to the burning location must occur by mechanical conveyor as much as possible, finished by pneumatic feeding • Moisture and calorific value though a rotating valve and dosing system. • Chlorine • CAPEX: €1 million to €2 million • Particle size • OPEX: €5 to €10 per ton • Homogeneity. • For larger capacities (more than 5 tons per hour): • A storage facility must be created (for example, a simple hall, such as former clinker storage), adapted with fire detection and protection. • Hopper filling using a front loader • Injection line (as above) • Mechanical storage such as a top loader or a pit with an automatic crane; in this case, it is recommended to have one pit for deliveries and at least one pit to feed the hopper (in some cases, two cranes could be required) • CAPEX: €5 million to €15 million, depending on the capacity and civil works required • OPEX: €5 to €20 per ton, depending on manual or automatic operation and manpower costs Increasing the Use of Alternative Fuels at Cement Plants: International Best Practice 67 7. Municipal Waste Origin Composition Municipal waste is the waste produced by residents at home, The composition of municipal waste depends on the distribution of in offices, or in commercial activities. This waste could include housing (vertical/horizontal density), the city’s districts, seasonality, commercial waste, non-hazardous produced by industries, green the organization of collection (selective or not, using waste pickers waste, and street cleaning waste. or not), the city’s food standards, and other factors. Responsibility for the collection and treatment of municipal waste The standard composition of municipal waste available for energy is often in the hands of the city or regional council; however, in recovery is: some cases, this responsibility falls to residents, meaning that • LCV: 8 to 10 gigajoules per ton they must self-organize or create an entity responsible for waste • Chlorine: 0.5% to 1.5% collection and treatment (as was the case in Poland until July 2014). • Moisture content: 30% to 45% The city council could delegate (in part or total) the collection and/ • Metals: 2,000 to 5,000 parts per million or treatment of the waste. The standard composition of SRF/RDF is as follows: • Quality required for the main burner: • LCV: 20 to 25 gigajoules per ton • Moisture: <15% • Granulometry: 20 to 30 millimeters • Quality required for the precalciner: • LCV: 13 to 15 gigajoules per ton • Moisture: 15% to 25% • Granulometry: 50 to 80 millimeters • Quality required for the precombustion chamber: • LCV: 10 to 13 gigajoules per ton • Moisture: 20% to 40% • Granulometry: 100 to 200 millimeters Traditional Destination Supply Chains The typical destinations are: Options for organizing municipal waste collection include: • Landfilling, which is still the main destination in many countries, • Selective collection (more or less complex) to extract the although the level is decreasing because of: recyclable fraction at the source. The recyclable fraction is • Strict bans on landfilling of organic or recyclable waste (as in sent to a sorting center to separate out the material, and the some countries in Europe) or taxes on landfilling non-recyclable fraction is sent to final treatment • High population densities • Universal collection, with several transfer stations in large cities. • Ambitious recycling targets. • Incineration (with or without energy recovery), which is well developed in : • Countries with landfill limitations • Large cities or places where it is difficult to site a landfill. • Recycling, which is developing everywhere in response to regulations and targets related to the circular economy. 68 Appendix 1: Detailed Information by Alternative Fuel Type Preprocessing Environmental Implications For producing alternative fuel for cement plants, there are several The equipment and operations must be compliant with preprocessing options: environmental regulations related to municipal wastes. • Creation of a sorting line to extract the recyclables and the The main risks associated with SRF/RDF are: organic/inert fraction. The combustible fraction (without • Fire provoked by a shredding operation, by self-combustion (when recyclables) must be shredded to produce the quality expected by organic material is stored too long), and by other means the cement plant. • Solution: Fire detection equipment such as thermal cameras and • Creation of a mechanical biological treatment (MBT) plant adapted extinguishing equipment as well as frequent training of with different options for production of SRF/RDF (without or the workers in fire management without drying) that are associated with compost production or • Dust explosion; considering the fluffy aspect of the waste and the methanization organic fraction of the dust, dust accumulation in factories and • Drying is a key issue for producing alternative fuel that is storage facilities could provoke a dust explosion acceptable for use in cement plants. The drying could be biological • Solution: Frequent cleaning of the halls and superstructure of or thermal. In MBT, biological drying is mainly used. To use buildings. municipal waste to create the fuel quality required by the main The biological hazard is limited if workers wear personal protective burner, thermal drying is mandatory. equipment that is adapted to a potential exposure. These operations must be handled in a dedicated facility that has a permit for waste management. The workers must be trained in Barriers the risks. A quality management system must be implemented with • Cement plants must apply for a permit for waste (since SRF/RDF subcontracting (or not) to external labs. is considered waste), a procedure that could be complex and could The mixing of hazardous waste, including household hazardous raise strong opposition from stakeholders. waste, must be prohibited. • Competition with landfilling Carbon Dioxide Mitigation • RDF/SRF production must be competitive compared to landfilling. In some countries, the landfill gate fee is too low to cover the cost SRF/RDF produced from municipal waste contains a biomass of RDF/SRF preparation. fraction made of wood, paper, and organic wastes. Depending on the country, the biomass fraction is between 25 and 50 percent. • Regulation must limit access to landfilling (through technical restriction or taxation) and prioritize recycling and recovery CAPEX and OPEX operations. Producing alternative fuel from municipal waste requires two • Competition with incinerators steps: • Because an incinerator has high fixed costs, it must operate at • Sorting operation before or after shredding full capacity. The design must be strictly adapted to the needs of the waste to be incinerated. • Full shredding. • Regulation can give clear priority to the most efficient use of the For a sorting line with a capacity of 250,000 tons per year: waste (in the context of optimizing resource management), to • CAPEX: €1 million to €2 million plus €7 million to €8 million for energy efficiency, and to phasing out energy-intensive industrial bio-drying equipment. • OPEX: €5 to €15 per ton, depending on the fraction of recyclables • Cement plants operate a high-energy process and often approach and the market price. large-scale waste utilization. This investment is limited compared For the shredding line and the handling/sorting and injection line to building a new incinerator. in the cement plant, see Figure 41 in the section “non-hazardous • Bans on thermal use of this waste industrial waste.” • Co-processing (generally speaking, any thermal use) could be seen as competing with recycling, providing an easy and cheap solution for waste generators. • However, recycling activities need a destination for their own recycling wastes, which could lead to natural cooperation between recycling and co-processing. • The profitability of recycling is linked to the market price of the recycled material, and the alternative fuel also must be cheaper than the fossil fuel. Sustainable recycling must be profitable. • Technical barriers • Low calorific value and high moisture are the main barriers to the use of municipal waste in cement plants; as such, this waste segment is used only in the calciner. • Chlorine presence comes from two sources: PVC and the salt from food. Increasing the Use of Alternative Fuels at Cement Plants: International Best Practice 69 8. Sewage Sludge Origin Composition Sewage sludge is produced by sewage plants that receive municipal The composition of sewage sludge depends on the drying process or industrial wastewater. used in the plant. The wastewater is cleaned using biological treatment, and the The standard composition of sewage sludge available for energy pollution is concentrated in the sludge. recovery is: After biological treatment, the sludge could be dried through • LCV: 2 to 3 gigajoules per ton raw (10 to 15 gigajoules per ton after mechanical treatment (centrifuge or filter press) or a thermal drying) process. • Chlorine: 0.5% to 1% • Moisture content: 40% to 60% raw (5% to 20% after drying, depending on the process) • Metals: 1,000 to 5,000 parts per million, with special attention to aluminum and iron. Traditional Destination Supply Chains The typical destinations for sewage sludge are: The traditional transport method is by tanker truck or trailer. In the • Fertilizer use in fields case of simple trailers, the risk of spillage must be managed. • Different countries support this solution to reduce the use of synthetic fertilizers; however, limitations include the presence of pollutants, the real agronomic value, and seasonality • Incineration • This could occur at the sewage plant, in a municipal waste incinerator, or at a power plant. Preprocessing Environmental Implications For producing alternative fuel for cement plants, there are several The equipment and operations must be compliant with preprocessing options: environmental regulations related to sewage sludge. • Mechanical drying in the sewage plant The main risks associated with sewage sludge are: • Thermal drying, in the sewage plant or in the cement plant using • Smell, mainly for sludge with high or medium moisture content waste heat from the kiln. • Dust, in the case of dry sewage sludge. Biological hazard is limited if workers wear personal protective equipment that is adapted to a potential exposure. 70 Appendix 1: Detailed Information by Alternative Fuel Type Carbon Dioxide Mitigation Barriers Sewage sludge is considered to be 100 percent biomass. • Cement plants must apply for a permit for waste (since sewage sludge is considered waste), a procedure that could be complex and could raise strong opposition from stakeholders. • Competition with land spreading CAPEX and OPEX • Land spreading is not available year-round and requires large areas of land. CAPEX: • Land spreading should be limited to sewage sludge with real • For pasty sewage sludge, facility requirements are similar to those agronomic value and no pollutants and probably to small/ for industrial sludge. medium volumes of production. • For dried sewage sludge, pelletized or not, facility requirements • Competition with incinerators are similar to those for animal meal. • Some sewage plants want to operate a full line but need to find OPEX: €5 to €10 per ton a solution for the ash. • Co-incineration in power plants • Regulation applied to power plants must be compliant with waste incineration. • Ban on incineration of waste containing phosphorus • Some countries (such as Germany) could soon implement a ban on sewage sludge incineration to address limited phosphorus resources. • Recycling is considered as competition to co-processing. • Technical barrier: impact of moisture on calorific value. Increasing the Use of Alternative Fuels at Cement Plants: International Best Practice 71 9. Construction and Demolition Waste Origin Composition Construction and demolition waste originates from: The composition of construction and demolition waste depends on: • Building construction activities • The material used for construction: • The deconstruction of buildings. • In North America, wood is very important, whereas in Europe, The main characteristics of this waste segment are: rubble is the most important. • Huge heterogeneity of the materials • The deconstruction strategy • Geographic dispersion of these waste sources. • Preparation of the building before demolition, such as extraction of the doors, windows, and other components • Selective waste collection on-site (mainly for large operations) • Use of dedicated bins to collect the waste (for small operations). • Construction waste often is mixed with polluted packaging such as paint containers, glue, adhesives, and others. The standard composition of sorted construction and demolition waste is very variable. As an example, the composition for shingles is: LCV: 25 to 30 gigajoules per ton; chlorine: 0%. Traditional Destination Supply Chains The typical destinations for construction and demolition waste are: Construction and demolition waste is often collected in bins. • Landfilling In the case of strict rules on landfilling, sorting centers have been • In most countries, demolition waste is considered to be inert created near cities to allow for extraction of the burnable fraction. and is delivered to low-grade landfills without any control • In some cases, the burnable fraction is extracted and burned on-site • Construction waste can be disposed of in municipal landfills. • Material recovery • The rubble could be used as backfill in aggregate quarries or embankments • The packaging and production losses from construction waste are landfilled. Preprocessing Environmental Implications The preprocessing operation is linked to the sorting operation. The equipment and operations must be compliant with Sorting extracts different fractions such as doors, windows, environmental regulations related to construction and demolition shingles, wood parts, plaster board, and other components. wastes. These fractions can be shredded to produce alternative fuel: For the burnable portion, the environmental implications are the • Shingles made of paper with bitumen are used in cement plants in same as for SRF/RDF. Germany and North America. • For wood waste taken from houses (mainly in North America), dedicated facilities prepare the alternative fuel for cement plants. • The plastic fraction cannot be used in cement plants because of the presence of PVC. • Plasterboard has been used in the Republic of Korea, although the main problem is separating the cardboard from the gypsum. Both parts can be used separately or mixed. • Hazardous waste such as polluted packaging can be used in cement plants after shredding. The remaining portion of this waste could be crushed to produce aggregate. Several operations are ongoing (for example, in France) to recycle waste as aggregate in concrete production. 72 Appendix 1: Detailed Information by Alternative Fuel Type Carbon Dioxide Mitigation Barriers The wood fraction is 100 percent biomass. • Organizing an efficient collection network is key to producing alternative fuel usable for co-processing. • Cement plants cannot use these wastes in the form in which they are produced. CAPEX and OPEX • The creation of sorting lines near cities is helping to separate the different fractions to produce valuable alternative fuels and raw The CAPEX and OPEX are similar to those for non-hazardous materials. industrial waste. • Competition with landfilling (the main destination of this waste) • Regulation banning the landfilling of burnable or mixed waste is a major step to make this market available for cement plants. This ban must be combined with the enforcement of quality controls in landfills. • The standard for aggregate must be revised to allow for use of the inorganic portion of the waste. Increasing the Use of Alternative Fuels at Cement Plants: International Best Practice 73 10. Biomass/Green Wastes Origin Composition The term “green waste” includes different categories: The standard composition for crop waste (for example, coffee • Waste from crop production, for example: husk) is: • Out-of-date seeds, which could be considered hazardous waste • LCV: 17 gigajoules per ton (dry) depending on the pesticides applied to protect them • Chlorine: <0.5% • Rice husk, palm kernel shell, bagasse, coffee husk, cotton stalks, • Moisture content: 10% to 20% and others • Ash: Presence of silica causes high wear • Pesticide packaging or plastic from greenhouses (see “polluted • Granulometry: <15 millimeters packaging”) The standard composition for chicken litter is: • Green waste from urban and forestry services • LCV: 10 to 13 gigajoules per ton • Waste from agro-industries, for example: • Chlorine: 0.4% to 0.8% • Different kinds of sludge • Moisture content: 15% to 30% • Chicken litter and other animal waste • Ash: 10% to 30% • Glycerin from biofuel production. The standard composition for glycerin is: For waste from crop production and from urban and forestry • LCV: 25 to 35 gigajoules per ton services, production is scattered across large territories. • Chlorine: Marginal • Moisture content: 5% to 10% • Ash: 0% Traditional Destination Supply Chains The typical destinations for biomass and green wastes are: For crop waste, collection is a key issue. Two parameters must be • Burning on site considered: • Waste from crop production (rice husks, coffee husks, corn • Low density: 0.1 tons per cubic meter or less waste) is often burned directly in the field. This is typical for • Dispersion of the sources in small quantities across large areas. small-scale production, and the ash may have some fertilizing Collection could be optimized through the use of transfer stations, properties. However, keeping the waste in the field after which must be managed properly to protect the material from harvesting is often a source of disease for the next planting. long-term exposure to rain and other elements. • Waste from forestry operations is typically burned on-site. • Feeding cattle • Some sludge or crop production waste is used to feed cattle, either directly on small farms or following transformation. • Energy recovery is an important destination for this waste, given the high calorific value. Preprocessing Environmental Implications Preprocessing of biomass/green wastes is targeted at: Storage of biomass/green wastes must be managed properly to avoid: • Modifying the physical aspects • Rodents • Through grinding, pelletization, and other means • Fire caused by direct inflammation or fermentation • Decreasing the moisture content • Flying dust that could pollute communities around the plant. • Drying via solar or thermal means • Thermal drying can occur in the cement plant using waste heat from the kiln. • Concentrating the calorific value • Carbonization and torrefaction are two technologies available for biomass. 74 Appendix 1: Detailed Information by Alternative Fuel Type Carbon Dioxide Mitigation Barriers This waste material is 100 percent biomass. • Organizing waste collection is key and is often the main cost to be borne. • Cement plants could be involved in the collection system, as a way to also increase the degree of control over sourcing. CAPEX and OPEX • Low calorific value The facility requirements are comparable to those for • The calorific value of biomass is low (compared to traditional non-hazardous industrial waste. cement fuel), at around 10 gigajoules per ton. • Several technologies can be used to concentrate the calorific value, including drying (mechanical or thermal), torrefaction, and carbonization. Implementation of these technologies must bring real benefit, in terms of quality and compensation for costs. • Very low density • Storage and handling facilities must be designed to manage large quantities (to achieve the same heat load as is produced by traditional fuel). • The biomass contains ash (20 to 50 percent on dry) of varying composition (silica and others) as well as some large amounts of chlorine (1 to 5 percent on dry). • This must be taken into consideration in the raw mix of the cement kiln, given the low calorific value. • Competition with other energy recovery processes • This includes competition with own-use of the waste to produce heat. Most cement transformation processes require heat, and green wastes are considered a free source of energy; however, operating with poor yield and poor-quality emissions is not always taken into consideration. • In cement plants, energy efficiency is high and there is no production of ash. • Power plants with up-to-date emission treatment are being developed, but they require significant quantities of biomass to be profitable, given the high investment cost. • Cement plants have a cost advantage by using the biomass energy close to the source and because using it on-site requires limited investment. Increasing the Use of Alternative Fuels at Cement Plants: International Best Practice 75 11. Animal Meal Origin Composition Animal meal is produced in rendering plants, which are in charge of The standard composition of animal meal available for use in managing the waste from cattle, from slaughterhouses, and from energy recovery is: meat production. • LCV: 15 to 17 gigajoules per ton Regulation defines the standards for animal feed (such as for • Chlorine: <0.5%, depending on the cleaning strategy in the cattle and fish) and determines the quantity available for other rendering plants destinations such as energy recovery. Regulation defines different • Moisture content: 10% to 20% categories depending on the potential for pollution by disease. • Fat concentration: if fat >15%, there is a risk of clogging in the cement plant. Traditional Destination Supply Chains The typical destinations for animal meal are: The most convenient transport solution is by tanker truck, given • Use as animal feed, to feed different species of animals or fish, that animal meal is stored in silos at the production site. Trailers once the meal is certified as being free of disease also could be used, but they require a more complex receiving facility in the cement plant: use of a hopper and then transfer to • Use as fertilizer, given the agronomic value of animal meal the silo. • Energy recovery, which has become the main destination for animal meal in the case of a health crisis (for example, the “mad cow” crisis) or in the case of overproduction or specific qualities that are banned from previous use. Preprocessing Environmental Implications Preprocessing is performed at rendering facilities. It is Storage of animal meal must be managed properly to avoid: recommended that no preparation occur at cement plants. • Rodents • Fire caused by direct inflammation or fermentation • Explosion risk due to dust (the silo must be designed with this consideration in mind) • Smell (if a hopper is used for receiving the waste, it must be located in a building to avoid contact with water and the dissemination of smell outside). Carbon Dioxide Mitigation Barriers Animal meal is made from 100 percent biomass. • Regulation of animal meal plays a fundamental role. It must clearly define the different qualities as well as the allowable destinations for this waste, and it must be enforced strongly along the complete chain from animal waste to the final destination. CAPEX and OPEX • Cement plants must apply for a permit to use the waste, a procedure that could raise concern among the general population. The facility requirements include a silo and an injection line to the The local community could be opposed to the use of animal meal. main burner. • Sustainability of the resource. In Europe and other regions, • CAPEX: €0.5 million to €1 million cement plant capacity has been used during periods of health • OPEX: €5 per ton crisis. After the crisis, the waste streams return to their original destinations. The available quantities are limited, making the price less (or not at all) appealing to replace traditional fuel in cement plants. 76 Appendix 1: Detailed Information by Alternative Fuel Type APPENDIX 2 USE OF ALTERNATIVE FUELS IN CEMENT PRODUCTION: THE CASE OF POLAND Over the past decade, the cement sector in Poland has Union to implement the first waste shredding line to produce experienced rapid growth in its use of alternative fuel refuse-derived fuel (RDF). In 2001, the state tax was further sources for industrial processing. Two key factors helped simplified and extended to municipal waste. Responsibility initiate the adoption of co-processing (the use of waste as an for waste collection was transferred to landfill operators, energy source) in the country’s cement sector: which were easier to control and organize than hundreds of thousands of individual waste producers. 1. The willingness of Polish cement companies to reduce their operating costs by quickly replicating the alternative In parallel, with competition growing both for used tires fuel experience of international cement groups; and and for the small quantities of hazardous waste that were available, cement companies started investing in the 2. The enforcement of Polish waste regulations in order to development of handling facilities for RDF in their cement conform to relevant European Union directives, namely plants, creating significant demand that went beyond the the Waste Framework Directive, the Waste Incineration local market. This demand inflated the RDF price, further Directive, and the Landfill Directive. benefiting the cost-effectiveness of RDF preparation. At that Initial adoption of co-processing in Poland was relatively time, municipalities were not yet responsible for municipal slow and focused only on the use of hazardous waste, waste management; rather, this responsibility was scattered which was prohibited from being landfilled. The alternative among a small grouping of waste producers, including large fuel substitution rate grew to a few percent following the commercial buildings, housing communities, and farms, which adoption of the first waste regulation in 1998, which included had individual contracts with private waste management a small state tax on landfilling. Initially, this tax proved companies for the disposal of smaller quantities of waste. non-dissuasive and difficult to implement, largely because the In 2005, Germany adopted a ban on the landfilling of producers of waste were responsible for collecting it. At that recyclable and organic waste, leading to overproduction time, waste was particularly heterogeneous, which prompted of RDF. Poland’s shift toward alternative fuel development a simple solution: the blending of pasty, solid, and some liquid based on RDF was thus supported by importation of the fuel waste with sawdust for use in co-processing. from Germany for five years, before Germany increased its The second waste stream developed in Poland centered own waste burning capacity. At that point, the alternative on used tires. By law, tire manufacturers were responsible fuel substitution rate in Poland reached 20 percent. for the management of used tires, based on the principle In 2008, the state tax was increased sharply, climbing of “extended producer responsibility.” As a response, the from €4 per ton in 2007 to about €17 per ton, with a country’s tire manufacturers created a shared company to further doubling announced within the next 10 years. The manage this obligation through coordinated organization enforcement of this tax for municipal waste incited waste and subsidization of used tire collection. This propelled management companies to invest in alternative solutions. Poland’s alternative fuels substitution rate to the low teens. With cement plants capable of burning more than 1 million As the pressure grew to find ways to utilize non-hazardous tons of municipal waste per year, and given the relatively industrial waste, Poland used subsidies from the European lower financial and time investment required for building Increasing the Use of Alternative Fuels at Cement Plants: International Best Practice 77 a mechanical biological treatment plant compared to an The National Waste Management Plan 2014 (Official Journal incinerator, Poland’s waste management sector invested Polish Monitor of 2010 N°101, item 1183) included, among heavily in shredding lines for RDF preparation. others, the promotion of mechanical biological treatment for medium-sized communities, incineration for big cities (greater Waste management companies, supported by mid- to than 300,000 inhabitants), the reduction of landfilling (capped long-term contracts with the cement industry (which was at 35 percent of the 1995 waste weight for 2020), as well as guaranteeing a sustainable source of RDF produced locally), increasing the recycling targets to 50 percent by 2020. thus have developed numerous shredding lines in Poland. Some of the investment has been subsidized by European The Polish waste management market is now restructuring, Union and local government funds, supported in part by the with an increase in incineration capacities. Several state tax. Some of the investments also were shared between incinerators are under construction, targeting large cities. cement plants and RDF preparation plants. The typical However, co-processing is now a well-established waste investor profile was a local entrepreneur with the support of management stream—producing 1.5 million tons per year international companies or investment funds. The increase in of alternative fuels—and will grow to a capacity of about 2 the state tax immediately drove up the share of waste going to million tons of RDF, for a global production of municipal recycling and heat recovery, which more than doubled from 8 waste of between 15 and 20 million tons per year. To stay percent in 2007 to 18 percent in 2008 and 22 percent in 2009. competitive, Polish cement plants are now looking for innovative solutions to decrease RDF preparation costs and At that point, shredding line operators were sourcing waste increase the use of less-prepared wastes. New technologies from the industrial sector (obtaining good-quality waste for are under investigation based on longer residence time in the a low gate fee) as well as from the municipal waste sector, calciner or the use of external pre-burners (“hot disks”). with large cities being the main providers. The extension of sourcing to include municipal waste resulted in a degree As shown in Table 1, the alternative fuel substitution rate of downgrading of RDF quality, but the cement sector in Poland reached 45 percent in 2011. It has continued to continued the effort and pushed the substitution rate to increase in recent years and is now above 60 percent, with 40 percent in 2010. some cement plants using up to 85 percent alternative fuel. Once the capacity of RDF production lines reached an To summarize, the expansion of co-processing in Poland was equilibrium with the alternative fuel capacity of cement made possible as a result of: plants, the cement companies were able to pressure RDF producers to further improve the fuel quality. To face this 3. Strong commitment of the cement sector, including new demand, RDF producers had to innovate, improving through: grasping the alternative fuel market the quality of the RDF significantly through better sorting opportunities as they were emerging; establishing and drying sequences (thermal or biological). In parallel, mid-term and/or long-term contracts with the waste the cement plants developed new tools to improve drying, management sector; smart and continuous investments such as by installing thermal dryers that used the waste heat in the handling (and in some cases preparation) from the kilns. A new increase to the state tax then put more of alternative fuels; and the development of skills waste on the market—and at a better price—confirming the in kiln operation to accept low-quality alternative trend toward alternative fuel use. fuels.
Ongoing enforcement of waste regulations, particularly those related to landfilling. On July 1, 2013, a new law was issued (Journal of Law of 4. A favorable economic context comprising smart national 2013, item 1399 and item 21), transferring the responsibility and international investments, taxation on landfilling, for municipal waste management to the municipalities as and some alternative fuel opportunities supported by well as capping the municipal waste tax paid by each citizen European subsidies. at €17 per year. 78 Appendix 2: Use of Alternative Fuels in Cement Production: The Case of Poland ifc.org 2017 June