Environmental, Health, and Safety Guidelines LARGE VOLUME INORGANIC COMPOUNDS MANUFACTURING AND COAL TAR DISTILLATION WORLD BANK GROUP Environmental, Health and Safety Guidelines for Large Volume Inorganic Compounds Manufacturing and Coal Tar Distillation the results of an environmental assessment in which site- Introduction specific variables, such as host country context, assimilative The Environmental, Health, and Safety (EHS) Guidelines are capacity of the environment, and other project factors, are taken technical reference documents with general and industry- into account. The applicability of specific technical specific examples of Good International Industry Practice recommendations should be based on the professional opinion (GIIP) 1. When one or more members of the World Bank Group of qualified and experienced persons. When host country are involved in a project, these EHS Guidelines are applied as regulations differ from the levels and measures presented in the required by their respective policies and standards. These EHS Guidelines, projects are expected to achieve whichever is industry sector EHS guidelines are designed to be used more stringent. If less stringent levels or measures than those together with the General EHS Guidelines document, which provided in these EHS Guidelines are appropriate, in view of provides guidance to users on common EHS issues potentially specific project circumstances, a full and detailed justification for applicable to all industry sectors. For complex projects, use of any proposed alternatives is needed as part of the site-specific multiple industry-sector guidelines may be necessary. A environmental assessment. This justification should complete list of industry-sector guidelines can be found at: demonstrate that the choice for any alternate performance www.ifc.org/ifcext/enviro.nsf/Content/EnvironmentalGuidelines levels is protective of human health and the environment. The EHS Guidelines contain the performance levels and Applicability measures that are generally considered to be achievable in new This EHS Guideline includes information relevant to chemical facilities by existing technology at reasonable costs. Application manufacturing projects and facilities, and covers the production of the EHS Guidelines to existing facilities may involve the of large volume inorganic compounds (LVIC), including establishment of site-specific targets, with an appropriate ammonia, acids (nitric, hydrochloric, sulfuric, hydrofluoric, timetable for achieving them. phosphoric acid), chlor-alkali (e.g. chlorine, caustic soda, soda The applicability of the EHS Guidelines should be tailored to the ash, etc.), carbon black, and coal tar distillation (naphthalene, hazards and risks established for each project on the basis of phenanthrene, anthracene). This document is organized according to the following sections: 1 Defined as the exercise of professional skill, diligence, prudence and foresight that would be reasonably expected from skilled and experienced professionals engaged in the same type of undertaking under the same or similar Section 1.0 — Industry-Specific Impacts and Management circumstances globally. The circumstances that skilled and experienced Section 2.0 — Performance Indicators and Monitoring professionals may find when evaluating the range of pollution prevention and Section 3.0 — References and Additional Sources control tec hniques available to a project may include, but are not limited to, Annex A — General Description of Industry Activities varying levels of environmental degradation and environmental assimilative capacity as well as varying levels of financial and technical feasibility. DECEMBER 10, 2007 1 Environmental, Health, and Safety Guidelines LARGE VOLUME INORGANIC COMPOUNDS MANUFACTURING AND COAL TAR DISTILLATION WORLD BANK GROUP and intermediates; waste water handling; flares; and emergency 1.0 Industry-Specific Impacts vents. and Management The following section provides a summary of EHS issues Although chemical manufacturing emissions vary depending on associated with facilities manufacturing large volume inorganic the specific process and related feedstok, the most common compounds (LVIC) and for coal tar distillation, which occur pollutants that may be emitted from point or fugitive sources during the operational phase, along with recommendations for during routine operations, include: carbon dioxide (CO2), their management. nitrogen oxides (NOX), sulfur oxides (SOX), ammonia (NH3), acids and acid mists, chlorine gas, and dust. Volatile organic Recommendations for the management of EHS impacts compounds and tar fume are emitted from carbon black and common to most large industrial facilities during the construction coal tar distillation plants. and decommissioning phases are provided in the General EHS Guidelines. The gaseous emissions from the chemical manufacturing industry can be typically controlled by adsorption or absorption. 1.1 Environmental Parti culate emissions, usually less than 10 mi crons in aerodynamic diameter, are controlled by highly efficient systems Typical environmental issues associated with LVIC such as bag filters, electrostatic precipitators, etc. manufacturing include the following: Chemical manufacturing facilities are large consumer of energy. • Air emissions Exhaust gas emissions produced by the combustion of gas or • Liquid effluents other fuels in turbines, boilers, compressors, pumps and other • Generation of solid waste engines for power and heat generation, are a significant source • Hazardous materials management of mainly CO2 and NOX. Guidance for the management of • Noise small combustion source emissions with a capacity of up to 50 • Odors megawatt hours thermal (MWth), including air emission • Decommissioning standards for exhaust emissions, is provided in the General EHS Guidelines. Guidance for the management of combustion Air Emissions source emissions from larger sources of power generation is The manufacture and use of inorganic chemicals and chemical provided in the EHS Guidelines for Thermal Power. products typically generate s large volume of emissions; however, current technology allows for closed system Greenhouse Gases (GHGs) operations, thus significantly reducing emission releases to the The LVIC manufacturing industry is a significant emitter of environment. greenhouse gases, especially carbon dioxide (CO2). GHGs are generated from the process as well as during the production of Emission sources from chemical processes include process tail its highly demanding energy needs. Measures to increase gases, heaters and boilers; valves, flanges, pumps, and compressors; storage and transfer of raw materials, products DECEMBER 10, 2007 2 Environmental, Health, and Safety Guidelines LARGE VOLUME INORGANIC COMPOUNDS MANUFACTURING AND COAL TAR DISTILLATION WORLD BANK GROUP energy efficiency and installation of Low NOX burners should be • Implementation of leak detection and repair programs; adopted since they will contribute to reduce CO2 generation. • Installation of continuous monitoring in all sensitive areas. Attempts should be made to maximize energy efficiency and Venting and Flaring design facilities for lowest energy use. Recommendations on Venting and flaring are important safety measures used in energy efficiency are addressed in the General EHS chemical manufacturing facilities to ensure gas is safely Guidelines. disposed of during process start up and shut down or in the event of an emergency, power or equipment failure, or other Fugitive Emissions plant upset conditions. Fugitive emissions are associated with leaks from pipes, valves, connections, flanges, packings, open-ended lines, floating roof Recommended methods to prevent, minimize, and control air storage tank and pump seals, gas conveyance systems, emissions from venting and flaring include: compressor seals, pressure relief valves, tanks or open pits / containments, and loading and unloading operations of • Use best practices and new technologies to minimize products. Due to the presence of hazardous products in LVIC releases and potential impacts from venting and flaring manufacturing facilities (i.e. NH3 and chlorine), methods for (e.g., efficient flare tips, reliable pilot ignition system, controlling and preventing fugitive emissions should be minimization of liquid carry over, control of odor and visible considered and implemented in their design, operation, and smoke emissions, and locating flare at a safe distance from maintenance. The selection of appropriate valves, flanges, potential human and environmental receptors); fittings, seals, and packings should be based on their capacity to • Estimate flaring volumes and develop flaring targets for reduce gas leaks and fugitive emissions. new facilities, and record volumes of gas flared for all flaring events; Use of open vents in tank roofs should be avoided by installing • Divert gas emissions from emergency or upset conditions pressure relief valves. Storages and unloading stations should to an efficient flare gas system. Emergency venting may be be provided with vapor recovery units. Vapor processing acceptable under specific conditions where flaring of the systems may consist of different methods, such as carbon gas stream is not possible, on the basis of a risk analysis. adsorption, refrigeration, recycling collecting and burning. Justification for no gas flaring system should be fully documented before an emergency gas venting facility is Examples of measures for reducing the generation of fugitve considered. emissions include: Process Air Emissions – Ammonia Manufacturing • Rigorous maintenance programs, particularly in stuffing Process air emissions from ammonia plants consist mainly of boxes on valve stems and seats on relief valves, to reduce hydrogen (H2), carbon dioxide (CO2), carbon monoxide (CO), or eliminate accidental releases; and ammonia (NH3). Concentrated carbon dioxide emissions • Selection of appropriate valves, flanges, fittings; are generated from CO2 removal in these facilities. Fugitive • Well designed, constructed, operated and maintained emissions of NH3 (e.g. from storage tanks, valves, flanges, and installations; DECEMBER 10, 2007 3 Environmental, Health, and Safety Guidelines LARGE VOLUME INORGANIC COMPOUNDS MANUFACTURING AND COAL TAR DISTILLATION WORLD BANK GROUP tubing) may also occur, especially during transport or transfer. • SO2 resulting from incomplete oxidation and SO3 resulting Non-routine emissions associated with process upsets or from incomplete absorption and droplets of sulfuric acid accidents may contain natural gas, CO, H2, CO2, volatile organic (H2SO4) from sulfuric acid manufacturing plants; compounds (VOCs), nitrogen oxides (NOX) and NH3. • Gaseous fluorides and dust from phosphoric / hydrofluoric acid plants; Recommended emission prevention and control measures • Hydrochloric acid (HCl) gas, chlorine, and chlorinated include the fo llowing: organic compounds resulting primarily from gases exiting the HCl purification system in HCl production; • Use synthesis NH3 purge gas treatment to recover NH3 and • Fluorine, hydrofluoric acid (HF), and silicon tetrafluoride H2 before combustion of the remainder in the primary (SiF 4) from digestion of phosphate rock and dust from reformer; handling of phosphate rock in HF production. Particulate • Increase the residence time for off-gas in the high- matter is emitted during handling and drying of the temperature zone; fluorspar. In hydrofluoric acid facilities fluorine emissions • Connect ammonia emissions from relief valves or pressure present in the final vents are typically very low following the control devices from vessels or tanks to a flare or to a required treatment. water scrubber; • Combine ammonia and urea facilities to reduce (through Recommended emission prevention and control measures reuse in urea plant) ammonia process-generated CO2 include the following: emissions2. Another industrial alternative is to combine with methanol production. It is noted that, in methanol • The plant should be equipped with pre-condensers that production facilities, hydrogen is produced from natural remove water vapor and sulfuric acid mist, and with gas, by means of a steam reforming unit followed by a condensers, acid scrubbers, and water scrubbers that methanol unit. This process, therefore, does not fully minimize the release of HF, SiF 4, SO2, and CO2 from the eliminate CO2 emissions because of the energy used to run tail-gas; the hydrogen production and methanol synthesis units. • Use high-pressure adsorption process for nitric acid production to minimize the concentration of NOX in the tail Process Air Emissions – Acid Manufacturing gas; Process emissions from acid plants include the following: • Treat the off-gases from nitric acid plants using cata lytic NOX removal; • Nitrous oxide (N2O) and NOX from nitric acid manufacturing • Consider using double absorption process for H2SO4 plants, particularly from tail gas emissions 3; plants. Plants operating on a single absorption process shouild consider implementation of the following: 2 Ammonia process-derived CO2 can be almost totally consumed if the o Cesium catalyst in the last bed produced ammonia is transformed into urea (1t NH3 - 1.5 t urea). 3 The lowest NOX emission levels currently achieved in a modern plant without added pollution abatement are between1,000 to 2,000 ppmv for medium pressure absorption and 100 to 200 ppmv for high pressure absorption. For new can be at 100 ppmv, which is equivalent to 0.65kg NOX (expressed as NO2) per plants in normal operating conditions the NOX emission level (excluding N 2O) ton of 100% nitric acid produced. DECEMBER 10, 2007 4 Environmental, Health, and Safety Guidelines LARGE VOLUME INORGANIC COMPOUNDS MANUFACTURING AND COAL TAR DISTILLATION WORLD BANK GROUP o SO2 abatement by scrubbing with a neutralizing from liquefaction (H2, O2, N2, CO2) having a chlorine content compound from 1-8% of the raw chlorine gas produced are treated. Other o SO2 abatement with hydrogen peroxide (H2O2) emissions from chlor-alkali plants are linked to the brine • Control dust emissions from the flue-gases of directly purification. Air emissions from mercury cell technology include heated dryers and/or from pneumatic conveying gases mercury vapors, emitted as fugitive emissions from the cells using cyclones and filters; (e.g. cell room ventilation gas). • Recover the fluorine as fluosilicic acid; a dilute solution of Principal air emissions from soda ash manufacturing are fluosilicic acid should be used as the scrubbing liquid. process carbon dioxide and particulate emissions from ore Fluorine, released during the digestion of phosphate rock calciners, soda ash coolers and dryers, ore crushing, screening, and during the concentration of phosphoric acid, should be and transportation operations, product handling and shipping removed by scrubbing systems; operations. Emissions of products of combustion, such as • Control emissions of HF by the condensing, scrubbing, and carbon monoxide, nitrogen oxides, and sulfur dioxide, occur absorption equipment used in the recovery and purification from direct- fired process heating units such as ore calcining of the hydrofluoric and hexafluorosilicic acid products; kilns and soda ash dryers. Ammonia may also be emitted. • Minimize HF emissions, maintaining a slight negative Nitrogen oxides are produced in small quantities inside the kiln pressure in the kiln during normal operations; by the oxidation of nitrogen contained in the air used in the • Install caustic scrubbers to reduce the levels of pollutants combustion process, and sulfur oxides by the oxidation of in the HF tail-gas, as needed; compounds containing sulfur in the limestone. • Control dust emissions by bag filters at the fluorspar silos and drying kilns. Collect dust from the gas streams exiting Recommended emission prevention and control measures the kiln in HF production and return the dust to the kiln for include the fo llowing: fur ther processing; • Control dust emissions from fluorspar handling and storage • Discontinue use of mercury and diaphragm cell processes, with flexible coverings and chemical additives, and where possible, and adopt new membrane cell process. • Control dust emissions from phosphate rock during Alternatively, install improved cell part materials (e.g. transport, handling and storage, using enclosed systems dimensionally stable anodes (DSA®), modified diaphragm), and bag filters. as needed; • Prepare mercury mass balances to account for all mercury Process Air Emissions – Chlor-Alkali Plants use; The principal chlor-alkali processes are mercury, diaphragm, • Optimize process to keep the cells as close as possible; and membrane cell electrolysis. The most significant emi ssions • Install mercury distillation units to recover mercury; from all three processes are both fugitive and point source • Ensure that that the mercury cell end boxes and caustic chlorine gas emissions. Sources of potential signifi cant chlorine boxes are properly sealed, thus eliminating fugitive emissions are normally associated with the chlorine destruction releases; unit where emissions from non-condensable gases remaining DECEMBER 10, 2007 5 Environmental, Health, and Safety Guidelines LARGE VOLUME INORGANIC COMPOUNDS MANUFACTURING AND COAL TAR DISTILLATION WORLD BANK GROUP • Design the chlorine absorption unit with a treatment • Use primary feedstock with a sulfur content in the range of capacity sufficient to absorb the full cell-room production 0.5 - 1.5 percent4; and prevent emissions of chlorine gas in the event of a • Preheat process air in heat exchangers using the hot process upset until the plant can be shut down. The gases (containing carbon black) leaving the furnace black absorption unit should be designed to lower the chlorine reactor; content in the emitted gas to less than 5 mg/m3 in the worst • Install and maintain high-performance bag filters to ensure case scenario; high carbon black collection efficiency and minimum • Direct all chlorine-containing waste gas streams to the product losses of the residual carbon black in the filtered chlorine absorption unit and ensure that the system is gas tail gas; tight; • Utilize the energy content of the tail gas (by burning the • Install chlorine gas detectors in areas with a potential risk gas and using the energy produced); of chlorine leaks to allow for immediate leakage detection; • Primary NOX reduction techniques should be applied to • Use carbon tetrachloride- free chlorine liquefaction and reduce the NOX content in flue-gas originating from tail-gas purification processes. The use of carbon tetrachloride combustion in energy producing systems 5; (CCl4), for removal of nitrogen trichloride (NCl3) and for • Install fabric filters for the air conveying system, vent absorption of tail gas, should be avoided and discontinued; collection system, and dryer purge gas6; • In soda ash facilities, control particulate emissions from ore • Vent un-combusted tail-gas only during emergencies, start- and product handling operations by either venturi up and shut- down periods, and during periods of grade scrubbers, or baghouse filters, electrostatic precipita tors, change. and/or cyclones and recycle the collected particulates. Process Air Emissions – Coal Tar Distillation Process Air Emissions – Carbon Black Manufacturing Although coal tar distillation emissions occur in normal operating An important potential source of emission to air is the tail gas conditions, the key emissions from these processes that warrant coming from the reactor after carbon black separation, which is control are those consisting of tar fume, odor, polycyclic a low calorific gas with a high moisture content due to the aromatic hydrocarbons (PAH), and particulate ma tter, which quench water vapor. The tail-gas composition may vary may originate from facility processes including delivering, considerably according to the grade of carbon black being storing, heating, mixing, and cooling tar. produced and the feedstock used. It may contain H2, CO, CO2, reduced sulfur compounds (H2S, CS2 and COS), SO2, nitrogen Recommended emission prevention and control measures compounds (N2, NOX, HCN and NH3), VOCs such as ethane include the fo llowing: and acetylene, and carbon black particles that are not captured 4 Specific emission levels of 10 – 50 kg SOX (as SO2) per tonne of rubber grade by product separation bag filters. carbon black produced are possible, as a yearly average. 5 Plants emission levels associated with use of BAT are less than 0.6 g Recommended emission prevention and control measures NOX/Nm 3 as an hourly average at 3 % O2 during normal production. 6 For the low temperature air conveying and vent collector systems, assoc iated include the following: emission levels are 10 to 30 mg/Nm 3 as a half-hour average. For the dryer purge filter, associated emission levels are from less than 20 to 30 mg/Nm 3 as a half- hour average DECEMBER 10, 2007 6 Environmental, Health, and Safety Guidelines LARGE VOLUME INORGANIC COMPOUNDS MANUFACTURING AND COAL TAR DISTILLATION WORLD BANK GROUP • Use ground-based pumps and other methods to opti mize soot and ash removal may impact water discharged, if not tar deliveries to reduce emissions of tar fume and odor; properly handled. • Site storage tanks downwind of potential nearby receptors, Recommended measures to prevent, minimize, and control control temperature of stored materials7, and implement effluents from ammonia plants include: careful handling procedures to prevent odor nuisance; • Implement overfill prevention methods for bulk storage • Recover ammonia absorbed from purge and flash gases in tanks, such as high-level alarms or volume indicators; a closed loop system so that no aqueous ammonia • Used local exhaust ventilation adequate to collect and treat emissions occur; VOC emissions from mixing tanks and other processing • Recover soot from gasification in partial oxidation equipment. processes and recycle the recovered material to the process. Liquid Effluents Liquid effluents include process and cooling water, storm water, Effluents – Acids Manufacturing and other specific discharges (e.g. hydrotesting and cleaning, Effluents from nitric acid plants may be contaminated with mainly during facility start up and turnaround). 8 Process water nitrogen compounds. Effluents from hydrochloric acid plants discharges from LVIC manufacturing plants may include the can vary depending on manufacturing processes from traces of acid wash from scheduled cleaning activities and purges, which HCl when reacting H2 with Cl, to mineral salt (Na2SO4) when the are part of daily operation. Additional potential sources of acid is produced by reacting sodium chloride with sulfuric acid. effluents may include scrubbers, if used as air emission control systems. Accidental releases or leaks from product storage Liquid releases from phosphoric acid plants mainly consist of tanks such as refrigerated ammonia and acid storage may also the liquid effluents originating from vacuum cooler condensers produce effluents. Other sources include acidic and caustic and gas scrubbing systems used for condensation and cleaning effluents from the boiler feed water preparation for the different of the vapors that evolve in the various process stages. These steam systems. Cooling water and storm water management condensed acidic vapors contain mainly fluorine and small are addressed in the General EHS Guidelines. amounts of phosphoric acid. The fluorine released from the reactor and evaporators can be recovered as a commercial by- Effluents and control specific to different types of chemicals product (fluorosilicic acid 20-25 percent). manufacturing plants are described below. Recommended measures to prevent, minimize, and control Effluents – Ammonia Manufacturing effluents from acid plants include: Plant discharges, during normal operation, may occur due to process condensates or due to the scrubbing of waste gases • Use closed-loop reactors and evaporators to eliminate containing ammonia and other products. In partial oxidation, process wastewater; • Recirculate the water used for the transport of 7 The rate of fume emission doubles for approximately every 11ºC rise in temperature. phosphogypsum into the process after settling; 8 Facility turnarounds are usually limited to once every three to four years and last a few weeks. DECEMBER 10, 2007 7 Environmental, Health, and Safety Guidelines LARGE VOLUME INORGANIC COMPOUNDS MANUFACTURING AND COAL TAR DISTILLATION WORLD BANK GROUP • Treat scrubber effluent with lime or limestone or use • Purify brine by pH adjustment, precipitation, flocculation seawater as a scrubbing liquid to precipitate fluorine as and filtration to keep impurities at acceptable levels. The calcium fluoride; consumption of chemicals which are employed to purify the • Install a separator to remove phosphoric acid droplets from brine varies from plant to plant depending on the impurities vacuum flash coolers and vacuum evaporators emissions of the brine; before scrubbing to minimize contamination of the scrubber • Recycle brine in membrane technology, removing effluent with phosphorous pentoxide (P2 O5); impurities by ion exchange resin units. Regeneration of • Recover fluorosilicic acid (H2SiF 6) from treatment of tail resins requires caustic soda and acid washing; gases from hydrofluoric units for use as a feed material or • Minimize consumption and discharge of sulfuric acid by for the manufacture of fluorides or silicofluorides. H2SiF 6 means of on-site re-concentration in closed loop can also be chemically combined to produce CaF2 and evaporators. The spent acid should be used to control pH silica. in process and waste water streams; resold to a user that accepts this quality of acid; or returned to a sulfuric acid Effluents – Chlor-Alkali Plants manufa cturer for re-concentration; Brine is one of key waste streams of the chlor-alkali industry. • Use fixed bed catalytic reduction, chemical reduction, or Membrane cells may use recycled brine requiring other equally effective method to minimize discharge of dechlorination. Specifically for membrane technology, brine free oxidants 11; purification is of critical importance to long membrane life and • Adopt carbon tetrachloride- free chlorine liquefaction and high efficiency. The main components in brine purification purification processes; wastes are sulfate, chloride, free oxidants, chlorate, bromate, • Use acid conditions in the anolyte (pH 1-2) to minimize the and carbon tetrachloride. formation of chlorate (ClO3) and bromate (BrO3), and chlorate destruction in the brine circuit to remove chlorate The main sources of liquid effluent from the soda ash process before purging in membrane plants 12. are typically waste water from the distillation and brine purification and cooling waters. The effluents are characterized Effluents – Carbon Black / Coal Tar Distillation by high levels of suspended solids 9. Another significant issue is Wastewater effluents are of relatively limited significance for the the potential discharge of heavy metals present in the main raw carbon black industry and in coal tar distillation units. materials 10. A zero discharge to water is possible for some types of carbon Recommended measures to prevent, minimize, and control black plants. However, the production of some rubber black and effluents from chlor-alkali plants include: nearly all specialty black grades require clean quench water. Suspended solids (mainly carbon black) should be filtered 9 Loads of suspended solids discharged with waste waters are generally 11 The emission level of free oxidants to water associated with implementation significant and range from 90 to 700 kg/t soda ash, with an average value of best available technuiques is less than 10 mg/l. estimated at 240 kg/t soda ash. 12 The chlorate level associated with best available techniques in the brine 10 For a soda ash plant with a capacity of around 600 kt/year, 10 tonnes per circuit is 1-5 g/l and the associated bromate level is 2-10 mg/l, and depends on year can be reached. the bromide level in the salt. DECEMBER 10, 2007 8 Environmental, Health, and Safety Guidelines LARGE VOLUME INORGANIC COMPOUNDS MANUFACTURING AND COAL TAR DISTILLATION WORLD BANK GROUP before discharge (or re-use) to levels less than 20 mg/l. After Recommended management strategies for spent catalysts filtration, process streams can be reused. include the following: Suspended solids, BOD and PAH concentrations should be • Proper on-site management, including submerging monitored in effluents from coal tar distillation units. pyrophoric spent catalysts in water during temporary storage and transport until they reach the final point of Hydrostatic Testing Water treatment to avoid uncontrolled exothermic reactions; Hydrostatic testing of equipment and pipelines usually needs • Off-site management by specialized companies that can significant amount of water (e.g., NH3 tanks may have recover and reclycle heavy metals (or precious metals from capacities of more than 20-30,000 m3). Chemical additives nitric acid plant catalysts) whenever possible. (typically a corrosion inhibitor, an oxygen scavenger, and a dye) are often added to the water to prevent internal corrosion. Storage and handling of hazardous and non-hazardous wastes should be conducted in a way consistent with good EHS In managing hydrotest waters, pollution prevention and control practice for waste management, as described in the EHS measures should be considered including: optimizing water General Guidelines. consumption and optimum dosage and careful selection of needed chemicals. Waste – Ammonia Manufacturing Ammonia manufacturing processes should not produce If discharge of hydrotest waters to the sea or to surface water is significant solid wastes 13. Spent catalysts and molecular sieves the only feasible alternative, a hydrotest water disposal plan management should be conducted as specified above. should be prepared. The plan should include, at a minimum, characteristics of the discharge point(s) rate of discharge, Waste – Acids Manufacturing chemical use and dispersion, environmental risk, and required Phosphogypsum is the most significant by-product in wet monitoring. phosphoric acid production 14. Phosphogypsum contains a wide range of impurities, some of which are considered a potential Hydrotest water disposal into shallow coastal waters should be hazard to the environment and public health. 15,16 avoided. Wastes Well- managed chemicals manufacturing plants should not 13 Spent catalysts and other solid waste should be less than 0.2kg per ton of product. generate significant quantities of solid wastes during normal 14 Around 4 - 5 tons of phosphogypsum (princ ipally calcium sulfate, CaSO4) are produced for every ton of phosphoric acid produced operation. Typical wastes generated include waste oils, spent 15 The impurities contained in the phosphate rock are distributed between the catalysts, sludge from wastewater treatment units, collected phosphoric acid produced and the calcium sulfate (gypsum); mercury, lead and radioactive components, where present, end up mainly in the gy psum, while dust from bag houses, bottom ashes from boilers, muds and arsenic and the other heavy metals such as cadmium end up mainly in the acid. The radioactivity of phosphate rock is mainly from radionuclides from the cakes from filtration units, etc. radioactive decay series of uranium-238. 16 Phosphate rock, phosphogypsum, and the effluents produced from a phosphoric acid plant have generally a lower radioactivity than the exem ption values given in the relevant international regulations and guidelines (for example, EU Directive 96/26/EURATOM) DECEMBER 10, 2007 9 Environmental, Health, and Safety Guidelines LARGE VOLUME INORGANIC COMPOUNDS MANUFACTURING AND COAL TAR DISTILLATION WORLD BANK GROUP Calcium sulfate (anhydrite) is produced as a by-product of exchange resins for secondary brine purification are rarely hydrofluoric acid (HF) manufacturing, containing between 0.2 to changed 19. Spent me mbranes 20 and gaskets from membrane 2.0 % of unreacted CaF2 and less than 1.0 % H2SO4. It also cells are other waste streams. contains the majority of the trace impurities contained in the The main solid wastes from soda ash unit are fines of limestone fluorspar 17. (30 – 300 kg/t soda ash) and non recycled grits at slaker (10 – Recommended measures to prevent or minimize solid waste 120 kg/t soda ash). generation and to manage solid waste from acid plants include: Recommended measures to prevent, minimize solid waste • Disposal of phosphogypsum in land facilities designed to generation and to manage solid waste from chlor-alkali plants prevent leaching to groundwater or surface water. Any include: effort should be made in order to reduce the impact of • Attempt to find reuse options for waste solids from the phosphogypsum disposal and possibly improve the quality of the gypsum, for its reuse. Disposal to sea is considered purification of salt brine; if the waste must be disposed of, consider the use of natural repositories, such brine cavities; non acceptable; • Select limestone with high CaCO3 content, appropriate • Refinement and sale of calcium sulfate anhydrite from HF physical characteristics, and limited content of heavy production for use in other products (e.g. cement), if metals and other impurities. possible. Waste – Chlor-Alkali Plants Waste – Carbon Black / Coal Tar Distillation Brine sludges are one of the largest waste streams of the chlor- Carbon black processes generate very limited amount of hazardous waste (oil residues). Coal- tar pitch is a black solid alkali industry. The quantity of brine filtration sludges mainly residue from the distillation of coal tar. The recovery of tar depends on the incoming salt characteristics, used for the chemicals leaves residual oils, including heavy naphtha, purification of the brine. The precipitated salts are removed from dephenolated carbolic oil, naphthalene drained oil, wash oil, the brine through decantation/clarification and filtration. The strained anthracene oil, and heavy oil. sludge may be removed discontinuously by flushing with a weak hydrochloric acid solution. The acid causes the precipitate to Recommended measures to prevent, minimize solid waste dissolve and the relatively harmless solution can be discharged generation and to manage solid waste include: with liquid effluent. Wastes are generated during the secondary brine purification and consist of used materials such as precoat • Reuse spent oil, oil sludge, and coal tar distillation residues and body feed material made of cellulose. The precoat filter as feedstock or fuel, if possible; sludge from the brine softener consists mainly of alpha- • Recycle off-specification carbon black back into the cellulose, contaminated with iron hydroxide and silica 18. Ion process. 17 About 3.7 tonnes of anhydrite per tonne of HF are produced as by -product. 18 19 Resins are regenerated about 30 times per year. Membrane cell plants report a figure of 600 g/t for sludge from brine softening. 20 The membranes have a lifetime of between 2 and 4 years. DECEMBER 10, 2007 10 Environmental, Health, and Safety Guidelines LARGE VOLUME INORGANIC COMPOUNDS MANUFACTURING AND COAL TAR DISTILLATION WORLD BANK GROUP Hazardous Materials Management During emergency depressurization, high noise levels can be Chemical manufacturing plants are required to assess the risks generated due to high pressure gases to flare and/or steam associated with the use and handling of hazardous materials release into the atmosphere. and implement practices to prevent and minimized such risks. Noise prevention and abatement strategies include: As indicated in the General EHS Guidelines, the application of these management practices should be documented in a written • Optimization of plant layouts in order to use the larger Hazardous Materials Management Plan 21. The purpose of this buildings as noise barriers and locating noise sources as plan is to establish and implement a systema tic set of preventive far as possible from existing receptors; actions against accidental releases of substances that can • Use of low noise generation equipment; cause serious harm to the public and the environment from • Installation of acoustic insulating barriers and silencers. short- term exposures and to mitigate the severity of releases that do occur. Noise abatement and control measures are similar to other large industries and are addressed in the General EHS Guidelines. Industry-specific pollution prevention and control practices include the following: Odors Odors from fugitive vapor releases or from wastewater • Accidental releases of fluids through should be prevented treatment plants may be generated in the LVIC manufacturing trough inspections and maintenance of storage and processes. Adequate controls to eliminate leaks should be conveyance systems, including stuffing boxes on pumps implemented to minimize fugitive releases and prevent odor and valves and other potential leakage points. Spillages of nuisances. dangerous intermediates and product should be contained and recovered or neutralized as quick as possible; Decommissioning • Secondary containment for the storage tanks storing liquids Chemical manufacturing facilities may have important quantities (i.e, ammonia, acids, etc.) and spare capacity for of solid and liquid hazardous materials such as CO2 removal dangerous products like chlorine should be installed as solutions, liquid ammonia, chlorine, soda, acids and products in discussed in the General EHS Guidelines; process and storage systems, off spec products, spent • Maintain good housekeeping practices, including catalysts, and mercury from mercury cell chlor-alkali plants. conducting product transfer activities over paved areas and prompt collection of small spills. Recommended management practices of decommissioning activities include the following: Noise In chemical manufacturing facilities, significant noise sources • In the case of mercury cell chlor-alkali plants, carefully plan include large size rotating machines, such as compressors and all decommissioning steps to minimize releases of mercury turbines, pumps, electric motors, air coolers, and fired heaters. and other hazardous substances (including dioxins and furans if graphite anodes were used) and to protect worker 21 See IFC Hazardous Waste Management Manual. DECEMBER 10, 2007 11 Environmental, Health, and Safety Guidelines LARGE VOLUME INORGANIC COMPOUNDS MANUFACTURING AND COAL TAR DISTILLATION WORLD BANK GROUP health and safety, and plan for disposition of the remaining • Chemical hazards due to acute and chronic exposure to mercury; toxic gases and other hazardous compounds; • Collect CO2 removal solutions in the ammonia plants and • Major hazards, including fires and explosions. all dangerous products for further handling and disposal as a hazardous waste material; Major hazards should be managed according to international regulations and best practices (e.g., OECD • Remove spent catalysts from NH3 and HNO3 plants for Recommendations 22, EU Seveso II Directive23 and USA EPA fur ther management as described in the solid waste Risk Management Program Rule 24). section above; • Recover and further manage NH3, Cl2, acids, and all other Chemical Hazards products from the synthesis section and storage tanks as The industry is characterized by the presence of toxic well as all products and intermediates from the storage compounds, including chlorine gas, ammonia, acids, caustic tanks according to hazardous materials management soda, amines, components of coal tar (e.g. mononuclear and guidance from the General EHS Guidelines. polycyclic aromatic hydrocarbons, phenols, and pyridine bases), General guidance on decommissioning and contaminated land which can be toxic when ingested, inhaled, or absorbed through remediation is provided in the General EHS Guidelines. the skin. The main health hazard usually associated with coal tar and its products is carcinogenicity due to long-term, 1.2 Occupational Health and Safety continued exposure of the skin to finely divided solid pitch (dust). The occupational health and safety issues that may occur during the construction and decommissioning of LVIC facilities are Recommendations to prevent, minimize, or control occupational similar to those of other industrial facilities, and their health impacts from exposure to toxic substances at these management is discussed in the General EHS Guidelines. facilities include: Facility -specific occupational health and safety issues should be identified based on job safety analysis or comprehensive hazard • Assess and minimize the concentrations of toxic or risk assessment, using established methodologies such as a substances in working areas in both normal and hazard identification study [HAZID], hazard and operability study emergency conditions. Rigorous workplace monitoring [HAZOP], or a quantitative risk assessment [QRA]. As a general protocols ought to be in place as part of the overall approach, health and safety management planning should occupational and health and safety management system. include the adoption of a systematic and structured approach for Protective clothing, including eye protection and PVC prevention and control of physical, chemical, biological, and gloves, should be worn, suitable respirators be available, radiological health and safety hazards described in the General and regular medical checkups be carried out on all EHS Guidelines. personnel, as needed; In addition, occupational health and safety issues for specific 22 OECD, Guiding Principles for Chemical Accident Prevention, Preparedness and Response, Second Edition (2003). consideration in chemical operations include: 23 EU Council Directive 96/82/EC, so-called Seveso II Directive, extended by the Directive 2003/105/EC. 24 EPA, 40 CFR Part 68, 1996 - Chemical accident prevention provisions . DECEMBER 10, 2007 12 Environmental, Health, and Safety Guidelines LARGE VOLUME INORGANIC COMPOUNDS MANUFACTURING AND COAL TAR DISTILLATION WORLD BANK GROUP • Install gas detectors in hazard areas, wherever possible. • Establishing a plant layout to reduce the frequency of For example, chlorine detectors should be placed in areas product transfers and the likelihood of accidental releases, of potential risk of chlorine leaks, giving immediate as well as to facilitate the collection of accidental releases; indication of the presence and location of any leakage; • Early detection of the release; • Ensure effective ventilation, where the lower boiling • Limiting the inventory which may be released by isolation products are handled; of the installation from large inventories and isolation and • Provide and use barrier creams formulated against blow-down of pressurized flammable gases inventories. aromatic hydrocarbons. Process areas, storage areas, utility areas, and safe areas should be segregated, preferably by adoption of safety Major Hazards distances. These distances can be derived from safety The most significant safety impacts are related to the handling analyses specific for the facility, considering the occurrence and storage of NH3 (volatile and poisonous in high of the hazards or from applicable standards or guidelines concentrations), chlorine (highly poisonous), caustic soda, nitric, (e.g., API, NFPA); hydrochloric, sulfuric, hydrofluoric, phosphoric acids and organic • Removing potential ignition sources; compounds and combustible gases such as natural gas, CO, • Removing or diluting the release and limiting the area and H2 and other process chemicals. These impacts may affected by the loss of containment. include significant acute exposures to workers and, potentially, to surrounding communities, depending on the quantities and Recommended industry specific measures to minimize the types of accidentally released chemicals and the conditions for above mentioned risks include: reactive or catastrophic events, such as fire and explosion. • Minimize the liquid chlorine inventory and the length of LVIC manufacturing facilities may generate or process large pipeline containing liquid chlorine; quantities of combustible gases, such as natural gas, H2, CO, • Design atmospheric ammonia storage tanks (- 33°C) with and other process chemicals. Synthetic Gas (SynGas; dual walls and an external concrete wall with the roof containing H2 and CO25) generated at ammonia plants may resting on the outer wall, and using an adequate margin cause “Jet Fires” if ignited in the release section, or give rise to between operating and relief pressure. Refrigerated Vapor Cloud Explosion, “Fireballs,” or “Flash Fires,” depending storage should be preferred for storage of large quantities on the quantity of flammable material involved, the degree of of liquid ammonia, since the initial release of ammonia in confinement of the cloud, and the congestion of the area the case of a line or tank failure is slower than with interested by the flammable cloud. pressurized ammonia storage systems; • Design chlorine storage tanks based on a specific analysis The risk of fire, explosion and other major hazards should be of major failure or accident risks and consequences, and minimized through the following measures: accounting on the possibility to safely recover and handle any product spills—consider low- temperature storage (- 25 Hydrogen and carbon monoxide have autoignition temperatures of 500°C and 609°C, respectively; therefore in some points of the SynGas generation 34°C) for large storage capacities, and provision of at least unit, where gas temperature is higher, potential gas releases may self ignite without the need of ignition sources. DECEMBER 10, 2007 13 Environmental, Health, and Safety Guidelines LARGE VOLUME INORGANIC COMPOUNDS MANUFACTURING AND COAL TAR DISTILLATION WORLD BANK GROUP one empty tank equal in capacity to the largest chlorine The design should include safeguards to minimize and control storage tank as an emergency spare; hazards to the community, through the following: • Given their highly corrosive and toxic nature, special • Identifying reasonable design leak cases; attention should be given to the handling and storage of acids including prevention of leaks or spills to effluent • Assessing the effects of the potential leaks on the waters by provision of secondary containment; separation surrounding areas, including groundwater and soil from critical drainage channels; and continuous monitoring pollution; and alarm detection systems (such as auto matic pH • Properly selecting the plant location in respect to the monitoring) of at- risk containment and drainage networks; inhabited areas, meteorological conditions (e.g. prevailing wind directions), and water resources (e.g., groundwater • Avoid pressurizing for unloading large quantities of nitric acid. The recommended material for tanks, vessels and vulnerability) and identifying safe distances between the accessories is low carbon austenitic stainless steel; plant area and the community areas; and • Only use specially trained and certified staff or contractors • Identifying the prevention and mitigation measures required for deliveries and transfer of all process chemicals, to avoid or minimize the hazards. including chemicals used in the CO2 removal unit of the If the facilities are located on the shore, the ship traffic ammonia plant. associated with the facilities should be considered in the assessment, analyzing the potential impact of the traffic on the 1.3 Community Health and Safety local marine traffic and activities and the potential impacts of Community health and safety impacts during the construction liquids leaks from the unloading or offloading operations. are common to those of most industrial facilities, and are Measures to avoid accidental impacts and minimize disturbance discussed in the General EHS Guideline. These impacts to other marine activities in the area should be assessed. Risk include, among other things, dust, noise, and vibration from analysis and emergency planning should include, at a minimum, construction vehicle transit, and communicable disease the preparation of an Emergency Management Plan, prepared associated with the influx of temporary construction labor. with the participation of local authorities and potentially affected communities. Other community health and safety hazards are The most significant community health and safety hazards common to those of most large industrial facilities, and are during the operation of chemical facilities are related to: discussed in the General EHS Guideline. • Handling and storage of hazardous materials including raw Community health and safety impacts during the materials, intermediaries, products and wastes near decommissioning are common to those of most large industrial populated areas; facilities, and are discussed in the General EHS Guideline. • Shipping of hazardous products (ammonia, chlorine, acids, These impacts include, among other things, transport safety, carbon black), with possibility of accidental leak of toxic disposal of demolition waste that may include hazardous and flammable gases; materials, and other impacts related to physical conditions and • Disposal of solid waste (phosphogypsum, sludge). the presence of hazardous materials after site abandonment. DECEMBER 10, 2007 14 Environmental, Health, and Safety Guidelines LARGE VOLUME INORGANIC COMPOUNDS MANUFACTURING AND COAL TAR DISTILLATION WORLD BANK GROUP Guidance for the management of these issues at chemical Guidance on ambient considerations based on the total load of plants is presented under Section 1.2 and in relevant sections of emissions is provided in the General EHS Guideline. the General EHS Guidelines including “Planning, Siting, and Design”, and “Emergency Preparedness and Response”. 2.0 Performance Indicators and Monitoring 2.1 Environment Emissions and Effluent Guidelines Tables 1 and 2 present emission and effluent guidelines for this sector. Guideline values for process emissions and effluents in this sector are indicative of good international industry practice as reflected in relevant standards of countries with recognized regulatory frameworks. These levels should be achieved, without dilution, at least 95 percent of the time that the plant or unit is operating, to be calculated as a proportion of annual operating hours. Deviation from these levels in consideration of specific, local project conditions should be justified in the environmental assessment. Effluent guidelines are applicable for direct discharges of treated effluents to surface waters for general use. Site-specific discharge levels may be established based on the availability and conditions in the use of publicly operated sewage collection and treatment systems or, if discharged directly to surface waters, on the receiving water use classification as described in the General EHS Guideline. Emissions guidelines are applicable to process emissions. Combustion source emissions guidelines associated with steam and power generation activities from sources with a capacity equal to or lower than 50 thermal megawatts are addressed in the General EHS Guideline with larger power source emissions addressed in the EHS Guidelines for Thermal Power . DECEMBER 10, 2007 15 Environmental, Health, and Safety Guidelines LARGE VOLUME INORGANIC COMPOUNDS MANUFACTURING AND COAL TAR DISTILLATION WORLD BANK GROUP Table 2. Effluent Levels Table 1. Air Emissions Levels Pollutant Units Guideline Value pH S.U. 6-9 Pollutant Units Guideline Value Temperature Increase °C <3 Ammonia Plants Ammonia Plants NH 3 mg/Nm 3 50 10 NH 3 mg/l NOX mg/Nm 3 300 (0.1 kg/t) 1 Particulate Matter mg/Nm 3 50 TSS mg/l 30 Nitric Acid Plants Nitric Acid Plants NOX mg/Nm 3 300 NH 3 mg/l 10 N 2O mg/Nm 3 800 Nitrates g/t 25 NH 3 mg/Nm 3 10 TSS mg/l 30 Sulfuric Acid Plants Sulfuric Acid Plants 450 Phosphorus mg/l 5 SO2 mg/Nm 3 (2 kg/t acid) Fluoride mg/l 20 60 TSS mg/l 30 SO3 mg/Nm 3 (0.075 kg/t acid) Phosphoric Acid Plants H 2S mg/Nm 3 5 Phosphorus mg/l 5 NOX mg/Nm 3 200 Fluoride mg/l 20 Phosphoric / Hydrofluoric Acids Plants TSS mg/l 30 Fluorides (gas eous) as HF mg/Nm 3 5 Hydrofluoric Acid Plants 50 Particulate Matter/CaF 2 mg/Nm 3 (0.10 kg/t phosphate kg/tonne Fluorides 1 rock) HF Chlor-alkali / Hydrochloric Acid Plants kg/tonne 1 (partial liquefaction) 1 Cl2 mg/Nm 3 Suspended Solids HF 3 (complete liquefaction mg/l 30 HCl ppmv 20 Chlor-alkali /Hydrochloric Acid Plant 0.2 TSS mg/l 202 Hg mg/Nm 3 (annual average emission of 1 g/t COD mg/l 1502 chlorine) AOX mg/l 0.52 Soda Ash Plants Sulfides mg/l 1 NH 3 mg/Nm 3 50 Chlorine mg/l 0.22 H 2S mg/Nm 3 5 0.05 mg/l Mercury -- NOx mg/Nm 3 200 0.1 g/t chlorine Particulate Matter mg/Nm 3 50 Toxicity to Fish Eggs TF 2 Soda Ash Plants Carbon Black Suspended solids kg/t 270 SO2 mg/Nm 3 850 Phosphorus kg/t 0.2 NOX mg/Nm 3 600 TSS mg/l 30 CO mg/Nm 3 500 Ammonia (as N) mg/l 10 Particulate Matter mg/Nm 3 30 VOC mg/Nm 3 50 Carbon Black Plants Coal Tar Distillation COD mg/l 100 Tar fume mg/Nm 3 10 Suspended Solids mg/l 20 VOC mg/Nm 3 50 Coal Tar Distillation Plants Particulate Matter mg/Nm 3 50 35 (monthly average) BOD 5 mg/l 90 (daily max imum) 50 (monthly average) TSS mg/l 160 (daily max imum) Anthracene, Naphthalene and 20 (monthly average) µg/l Phenanthrene (each) 60 (daily max imum) Notes: 1. Load based guideline: 0.1 kg/t of product 2. Non-asbestos diaphragm plants DECEMBER 10, 2007 16 Environmental, Health, and Safety Guidelines LARGE VOLUME INORGANIC COMPOUNDS MANUFACTURING AND COAL TAR DISTILLATION WORLD BANK GROUP Resource Use, Energy Consumption, Emission Notes: 1. European Fertilizer Manufacturers Association (EFMA). 2000. and Waste Generation 2. EU IPPC - Reference Document on Best Available Techniques in Large Volume Inorganic Chemicals - Solid and Others industry. December 2006. Tables 3 and 4 provide examples of resource consumption and 3. EU IPPC - Reference Document on Best Available Techniques in the Chlor-Alkali Manufacturing industry December 2001. waste generation benchmarks in this sector. Industry 4. EU IPPC - Reference Document on Best Available Techniques in Large Volume Inorganic Chemicals – Ammonia, Acids and Fertilizers Industries. benchmark values are provided for comparative purposes only October 2006. and individual projects should target continual improvement in these areas. Table 4. Emissions, Effluents and Waste Table 3. Resource and Energy Consumption Generation Industry Product Unit Industry Benchmark Parameter Unit Benchmark GJ lower heating value Ammonia 28.8 to 31.5(1) (LHV)/tonne NH3 Ammonia Plants Phosphoric Tonne phosphate rock/tonne 2.6-3.5 (1) CO2 from process tonne/tonne NH3 1.15-1.3 (1) Acid P2O5 NOX (advanced conventional kg/tonne NH3 0.29 – 0.32 KWh/tonne P2O5 120-180 (1) reforming processes and processes with reduced primary reforming) m 3 cooling water/tonne P2O5 100-150 (1) NOX (heat exchange autothermal kg/tonne NH3 0.175 Hydrofluoric Tonne CaF 2l/ tonne HF 2.1-2.2 (4) reforming) Acid Tonne H2SO4/tonne HF 2.6-2.7 (4) Nitric Acid Plants N 2O kg/tonne 100% 0.15-0.6 (4) KWh/tonne HF 150-300 (4) HNO3 Chlor-Alkali KWh/tonne Cl2 3000 without Cl NOX ppmv 5-75 (4) liquefaction 3200 with Cl liquefaction Sulfuric Acid Plants / evaporation(3) SO2 (Sulfur burning, double mg/Nm 3 30-350 (1)(4) contact/double absorption) Tonne NaCl/tonne Cl2 1.750 (3) SO2 (Single contact/single mg/Nm 3 100-450(4) g Hg/tonne of chlorine capacity 0.2-0.5 (3) absorption) (mercury cell plants) Phosphoric / Hydrofluoric Acid Plants Soda Ash GJ/tonne soda ash 9.7-13.6(2) Fluorides mg/Nm 3 0.6-5(4) Tonne limestone/tonne soda 1.09-1.82 (2) SO2 kg/tonne HF 0.001 – 0.01(4) ash Solid Waste (phosphogypsum) tonne/tonne P2O5 4-5 (1) Tonne NaCl/tonne soda ash 1.53-1.80 (2) Anhydrite (CaSO4) tonne/tonne HF 3.7 (4) m 3 cooling water/tonne soda 50-100 (2) Chlor Alkali Plants ash Cl2 (partial liquefaction) mg/Nm 3 <1 (3) Carbon Black KWh/tonne carbon black 430-550 (2) Cl2 (total liquefaction) mg/Nm 3 <3 (3) GJ/tonne carbon black 1.55-2 (2) Chlorates (brine circuit) g/l 1-5 (3) Bromates (brine circuit) mg/l 2-10 (3) Soda Ash Plants CO2 Kg/tonne soda ash 200-400 (2) Cl Kg/tonne soda ash 850-1100 (2) DECEMBER 10, 2007 17 Environmental, Health, and Safety Guidelines LARGE VOLUME INORGANIC COMPOUNDS MANUFACTURING AND COAL TAR DISTILLATION WORLD BANK GROUP Ca Kg/tonne soda ash 340-400 (2) 2.2 Occupational Health and Safety Na Kg/tonne soda ash 160-220 (2) Performance Waste water/suspended solids m 3/tonne/ tonne 8.5-10.7 / 0.09- soda ash 024 (2) Occupational Health and Safety Guidelines Carbon Black Plants Occupational health and safety performance should be kg/tonne of rubber SO2 10-50(2) evaluated against internationally published exposure guidelines, grade carbon black of which examples include the Threshold Limit Value (TLV®) NOX mg/Nm 3 <600(2) occupational exposure guidelines and Biological Exposure VOC mg/Nm 3 <50(2) Table 4 Notes : Indices (BEIs®) published by American Conference of 1. European Fertilizer Manufacturers Association (EFMA). 2000; Governmental Industrial Hygienists (ACGIH), 26 the United 2. EU IPPC - Reference Document on Best Available Techniques in Large Volume Inorganic Chemicals - Solid and Other Industries. Dec, 2006.; States National Institute for Occupational Health and Safety 3. EC IPPC - Reference Document on Best Available Techniques in the Chlor-Alkali Manufacturing industry December 2001; (NIOSH),27 Permissible Exposure Limits (PELs) published by 4. EC IPPC - Referenc e Document on Best Available Techniques in Large Volume Inorganic Chemicals – Ammonia, Acids and Fertilizers the Occupational Safety and Health Administration of the Industries. Oct, 2006. United States (OSHA), 28 Indicative Occupational Exposure Limit Values published by European Union me mber states, 29 or other Environmental Monitoring similar sources. Environmental monitoring programs for this sector should be implemented to address all activities that have been identi fied to Accident and Fatality Rates have potentially significant impacts on the environment, during Projects should try to reduce the number of accidents among normal operations and upset conditions. Environmental project workers (whether directly employed or subcontracted) to monitoring activities should be based on direct or indirect a rate of zero, especially accidents that could result in lost work indicators of emissions, effluents, and resource use applicable time, different levels of disability, or even fatalities. Facility rates to the particular project. may be benchmarked against the performance of facilities in this sector in developed countries through consultation with Monitoring frequency should be sufficient to provide published sources (e.g. US Bureau of Labor Statistics and UK representative data for the parameter being monitored. Health and Safety Executive)30. Monitoring should be conducted by trained individuals following monitoring and record-keeping procedures and using properly Occupational Health and Safety Monitoring calibrated and maintained equipment. Monitoring data should be The working environment should be monitored for occupational analyzed and reviewed at regular intervals and compared with hazards relevant to the specific project. Monitoring should be the operating standards so that any necessary corrective actions can be taken. Additional guidance on applicable 26 Available at: http://www.acgih.org/TLV/ sampling and analytical methods for emi ssions and effluents is 27 Available at: http://www.cdc.gov/niosh/npg/ 28 Available at: provided in the General EHS Guidelines. http://www.osha.gov/pls/oshaweb/owadisp.show_document?p_table=STANDAR DS&p_id=9992 29 Available at: http://europe.osha.eu.int/good_practice/risks/ds/oel/ 30 Available at: http://www.bls.gov/iif/ and http://www.hse.gov.uk/statistics/index.htm DECEMBER 10, 2007 18 Environmental, Health, and Safety Guidelines LARGE VOLUME INORGANIC COMPOUNDS MANUFACTURING AND COAL TAR DISTILLATION WORLD BANK GROUP designed and implemented by accredited professionals 31 as part of an occupational health and safety monitoring program. Facilities should also maintain a record of occupational accidents and diseases and dangerous occurrences and accidents. Additional guidance on occupational health and safety monitoring programs is provided in the General EHS Guidelines. 31 Accredited professionals may include Certified Industrial Hygienists, Registered Occupational Hygienists, or Certified Safety Professionals or their equiv alent. DECEMBER 10, 2007 19 Environmental, Health, and Safety Guidelines LARGE VOLUME INORGANIC COMPOUNDS MANUFACTURING AND COAL TAR DISTILLATION WORLD BANK GROUP National Fire Protection Association (NFPA). 2000. Standard 850: 3.0 References Recommended Practice for Fire Protection for Electric Generating Plants and High Voltage Direct Current Converter Stations. 2000 Edition. Quincy, Massachusetts Australian Government, Department of the Environment and Heritage. 2004. Emission Estimation Technique Manual for Inorganic Chemicals Manufacturing. Version 2.0. Canberra, Australia NFPA. 2004. Standard 120: Standard for Fire Prevention and Control in Coal Mines . 2004 Edition. Quincy, Massachusetts European Integrated Pollution Prevention and Control Bureau (EIPPCB). 2001. Integrated Pollution Prevention and Control (IPPC ) Reference Document on Paris Commission. 1990. Parcom Decision 90/3 of 14 June 1990 on Reducing Best Available Techniques in the Chlor-Alkali Manufacturing Industry. December Atmospheric Emissions from Existing Chlor-Alkali Plants. Paris, France 2001. Sevilla, Spain UK Environmental Agency. 1999a. IPC Guidance Note Series 2 (S2) Chem ical EIPPCB. 2006a. Integrated Pollution Prevention and Control (IPPC) Reference Industry Sector. S2 4.03: Inorganic Acids and Halogens. Bristol, UK Document on Best Available Techniques in Large Volume Inorganic Chemicals - Solids and Others Industry. October 2006. Sevilla, Spain UK Environmental Agency. 1999b. IPC Guidance Note Series 2 (S2) Chem ical Industry Sector. S2 4.04: Inorganic Chemicals. Bristol, UK EIPPCB. 2006b. Integrated Pollution Prevention and Control (IPPC) Reference Document on Best Available Techniques in Large Volume Inorganic Chemicals – Ammonia, Acids and Fertilisers. December 2006. Sevilla, Spain UK Environmental Agency. 2004a. Sector Guidance Note IPPC S4.03. Guidance for the Inorganic Chemicals Sector. Bristol, UK European Fertilizer Manufacturers Association (EFMA). 2000a. Best Available UK Environmental Agency. 2004b. Process Guidance Note 6/42 (04). Secretary Techniques for Pollution Prevention and Control in the European Fertilizer Industry. “Production of Ammonia,” Booklet No. 1. Brussels, Belgium of State's Guidance for Bitumen and Tar Processes . Bristol, UK EFMA. 2000b. Best Available Techniques for Pollution Prevention and Control in US Environmental Protection Agency (EPA). Office of Compliance. 1995. Sector Notebook Project. Profile of the Inorganic Chemical Industry. Was hington, DC the European Fertilizer Industry. “Production of Nitric Acid,” Booklet No. 2. Brussels, Belgium US EPA. 40 CFR Part 60, Standards of Performance for New and Existing EFMA. 2000c. Best Available Techniques for Pollution Prevention and Control in Stationary Sources: Subpart G—Standards of Performance for Nitric Acid the European Fertilizer Industry. “Production of Sulphuric Acid,” Booklet No. 3. Plants. Washington, DC. Available at http://www.gpoaccess.gov/cfr/index.html (accessed on October 2006) Brussels, Belgium US EPA. 40 CFR Part 60, Standards of Performance for New and Existing EFMA. 2000d. Best Available Techniques for Pollution Prevention and Control in the European Fertilizer Industry. “Production of Phosphoric Acid,” Booklet No. 4. Stationary Sources: Subpart H—Standards of Performance for Sulfuric Acid Brussels, Belgium Plants. Washington, DC. Available at http://www.gpoaccess.gov/cfr/index.html (accessed on October 2006) German Federal Government. 2002. First General Administrative Regulation Pertaining the Federal Immission Control Act (Technical Instructions on Air US EPA. 40 CFR Part 60, Standards of Performance for New and Existing Quality Control – TA Luft). Berlin, Germany Stationary Sources: Subpart T—Standards of Performance for the Phosphate Fertilizer Industry: Wet-Process Phosphoric Acid Plants. Washington, DC. Available at http://www.gpoaccess.gov/cfr/index.html (accessed on October German Federal Ministry for the Environment, Nature Conservation and Nuclear 2006) Safety. 2004. Promulgation of the New Version of the Ordinance on Requirements for the Discharge of Waste Water into Waters (Waste Water Ordinance - AbwV) of 17. June 2004. Berlin, Germany US EPA. 40 CFR Part 63, National Emission Standards for Hazardous Air Pollutants for Source Categories: Subpart AA—National Emission Standards for Hazardous Air Pollutants From Phosphoric Acid Manufacturing Plants. Helsinki Commission. 2002. Helcom Recommendation 23/6. Reduction of Washington, DC. Available at http://www.gpoaccess.gov/cfr/index.html Emissions and Discharges of Mercury from Chloralkali Industry. Helsinki, (accessed on October 2006) Finland. US EPA. 40 CFR Part 63, National Emission Standards for Hazardous Air Intergovernmental Panel on Climate Change (IPCC). 2006. Special Report, Pollutants for Source Categories: Subpart IIIII—National Emission Standards for Carbon Dioxide Capture and Storage, March 2006. Geneva, Switzerland Hazardous Air Pollutants: Mercury Emissions From Mercury Cell Chlor-Alkali Plants. Washington, DC. Available at http://www.gpoaccess.gov/cfr/index.html (accessed on October 2006) Kirk-Othmer, R.E. 2006. Encyclopedia of Chemical Technology. 5th Edition. John Wiley and Sons Ltd., New York, NY US EPA. 40 CFR Part 63, National Emission Standards for Hazardous Air Pollutants for Source Categories: Subpart NNNNN—National Emission Standards for Hazardous Air Pollutants: Hydrochloric Acid Production. DECEMBER 10, 2007 20 Environmental, Health, and Safety Guidelines LARGE VOLUME INORGANIC COMPOUNDS MANUFACTURING AND COAL TAR DISTILLATION WORLD BANK GROUP Washington, DC. Available at http://www.gpoaccess.gov/cfr/index.html (accessed on October 2006) US EPA. 40 CFR Part 414. Subpart G—Bulk Organic Chemicals. Washington, DC. Available at http://www.gpoaccess.gov/cfr/index.html (accessed on October 2006) US EPA. 40 CFR Part 414. Subpart I—Direct Discharge Point Sources That Use End-of-Pipe Biological Treatment. Washington, DC. Available at http://www.gpoaccess.gov/cfr/index.html (accessed on October 2006) US EPA. 40 CFR Part 414. Subpart J—Direct Discharge Point Sources That Do Not Use End-of-Pipe Biological Treatment. Washington, DC. Available at http://www.gpoaccess.gov/cfr/index.html (accessed on October 2006) US EPA. 40 CFR Part 415. Subpart F—Chlor-alkali Subcategory (Chlorine and Sodium or Potassium Hydroxide Production). Washington, DC. Available at http://www.gpoaccess.gov/cfr/index.html (accessed on October 2006) US EPA. 40 CFR Part 415. Subpart H—Hydrofluoric Acid Production Subcategory. Washington, DC. Available at http://www.gpoaccess.gov/cfr/index.html (accessed on October 2006) US EPA. 40 CFR Part 418. Subpart A—Phosphate Subcategory. Washington, DC. Available at http://www.gpoaccess.gov/cfr/index.html (accessed on October 2006) US EPA. 40 CFR Part 418. Subpart B—Ammonia Subcategory. Washington, DC. Available at http://www.gpoaccess.gov/cfr/index.html (accessed on October 2006) US EPA. 40 CFR Part 418. Subpart E—Nitric Acid Subcategory. Washington, DC. Available at http://www.gpoaccess.gov/cfr/index.html (accessed on October 2006) US EPA. 40 CFR Part 422. Subpart D—Defluorinated Phosphate Rock Subcategory. Washington, DC. Available at http://www.gpoaccess.gov/cfr/index.html (accessed on October 2006) US EPA. 40 CFR Part 422. Subpart E—Defluorinated Phosphoric Acid Subcategory. Washington, DC. Available at http://www.gpoaccess.gov/cfr/index.html (accessed on October 2006) US EPA. 40 CFR Part 458. Subpart A—Carbon Black Furnace Process Subcategory. Washington, DC. Available at http://www.gpoaccess.gov/cfr/index.html (accessed on October 2006) DECEMBER 10, 2007 21 Environmental, Health, and Safety Guidelines LARGE VOLUME INORGANIC COMPOUNDS MANUFACTURING AND COAL TAR DISTILLATION WORLD BANK GROUP Annex A: General Description of Industry Activities This EHS Guideline for Large Volume Inorganic Compound The natural gas reforming with steam and air is the simplest and (LVIC) Manufacturing and Coal Tar Distillation includes most efficient way of ammonia synthesis gas production and is Ammonia; Chlor-Alkali (i.e., chlorine, caustic soda, soda ash, today the most used. etc.); Acids (Nitric, Hydrochlodric, Sulfuric, Hydrofluodric, Ammonia is produced by an exothermic reaction of hydrogen Phosphoric); Carbon Black; and Coal Tar Distillation and nitrogen. This reaction is carried out in the presence of (naphthalene, phenanthrene, anthracene) sectors. It covers the metal oxide catalysts at elevated pressure. Catalysts used in the production of major intermediates and products for the process may contain cobalt, molybdenum, nickel, iron oxide / downstream industry covering many diversified sectors ranging chromium oxide, copper oxide / zinc oxide, and iron. The from fertilizers to plastics. It is characterized by large volume ammonia product, in liquefied form, is stored either in large productions, which can reach up to million ton per year and be manufactured in large facilities. atmospheric tanks at temperature of –33 degrees centigrade or in large spheres at pressures up to 20 atmospheres at ambient Ammonia 32 temperature. The raw material source of nitrogen is atmospheric air and it may be used in its natural state as compressed air or About 80 % of ammonia (NH3) is currently used as the nitrogen as pure nitrogen from an air liquefaction plant. Hydrogen is source in fertilizers, with the remaining 20 % applied in several available from a variety of sources such as natural gas, crude industrial applications, such as the manufacture of plastics, oil, naphtha, or off gases from processes such as coke oven or fibres, explosives, hydrazine, amines, amides, nitriles and other refineries. organic nitrogen compounds which serve as intermediates in dyes and pharmaceuticals manufacturing. Important inorganic Ammonia production from natural gas includes the following products manufactured from ammonia include nitric acid, urea process steps: removal of trace quantities of sulfur in the and sodium cyanide. Liquid ammonia is an important solvent feedstock; primary and secondary reforming; carbon monoxide and is also used as a refrigerant. shift conversion, removal of carbon dioxide, methanation, compression, ammonia synthesis, and ammonia product Ammonia plants may be built as stand-alone or integrated with refrigeration. Carbon is removed in the form of concentrated other plants at a site, typically with urea production. However CO2, which should preferably be used for urea manufacture or recent trends include combined ammonia with methanol other industrial purposes to reduce its release to the production. Hydrogen and / or carbon monoxide production can atmosphere. also be integrated with ammonia plants. An ammonia plant typically produces around 2,000 tonnes per day, but plants that Two other non conventional process routes include: (1) the can produce up to 3,400 tonnes per day have been built. addition of extra process air to the secondary reformer with cryogenic removal of the excess nitrogen, and (2) heat- exchange autothermal reforming. The second process route has 32 EIPPCB. 2006b; EFMA. 2000a DECEMBER 10, 2007 22 Environmental, Health, and Safety Guidelines LARGE VOLUME INORGANIC COMPOUNDS MANUFACTURING AND COAL TAR DISTILLATION WORLD BANK GROUP some environmental advantage because of the reduced need and burning the mixture over a platinum / rhodium catalyst; for firing in the primary reformer and the potential to lower cooling the resultant nitric oxide (NO) and oxidizing it to nitrogen energy consumption. It is a recent technology and, to date, built dioxide (NO2) with residual oxygen; and absorbing the nitrogen for a capacity of about 500 tonnes NH3 per day. dioxide in water in an absorption column to react into nitric acid. Large-capacity plants normally have dual-pressure design (e.g. Liquefied ammonia from production plants is either used directly medium-pressure combustion and high-pressure absorption), in downstream plants or transferred to storage tanks. From while small plants may have combustion and absorption storage the ammonia can be shipped to users, through road conducted at the same pressure. High pressure in the tankers, rail tank cars or ships. Ammonia is usually stored by absorption column reduces the nitrogen oxides (NOX) using one or other of three methods: emissions. Generation of NOX and nitrous oxide (N2O), which is a greenhouse gas, in nitric acid plants is significant; however • Fully refrigerated storage in large tanks with a typical catalytic conversion techniques can reduce the emission level capacity of 10,000 to 30,000 tonnes (up to 50,000) by more than 80 percent. • Pressurized storage spheres or cylinders with a capacity up to about 1,700 tonnes The recommended material for tanks, vessels and accessories • Semi-refrigerated tanks. is low carbon austenitic stainless steel. Transfer to transport vessels is typically via pumping or by gravity. Pressurizing for There are several storage types for refrigerated liquid products. unloading large quantities should be avoided. Nitric acid is The most important types are: transported using rail tank cars, road tankers and less • Single containment: a single-wall insulated tank, usually frequently, ships. with a containment bund around it; The typical capacity of modern plants for producing nitric acid is • Double containment: tanks with two vertical walls, both approximately 1,000 tons per day. designed to contain the stored liquid and withstand its hydrostatic pressure. The roof rests on the inner wall; and Sulfuric Acid 34 • Full containment: closed storage tanks with two walls, as The most important use of sulfuric acid (H2SO4) is in the for double containment, but with the roof resting on the phosphate fertilizer industry. Sulfuric acid is manufactured from outer wall and using an adequate margin between sulfur dioxide (SO2) produced by combustion of elemental sulfur. operating and relief pressure. Liquid sulfur is a product of the desulfurization of natural gas or Nitric Acid 33 the cleaning of coal flue-gas; another possible route is the melting of naturally occurring solid sulfur. Sulfur dioxide is also The production stages for nitric acid manufacture include the produced by the metals industry, through roasting and smelting following: vaporizing liquid ammonia; mixing the vapor with air processes generating off-gases with a sufficiently high 33 EIPPCB. 2006b; EFMA. 2000b. 34 EIPPCB. 2006b; EFMA. 2000c. DECEMBER 10, 2007 23 Environmental, Health, and Safety Guidelines LARGE VOLUME INORGANIC COMPOUNDS MANUFACTURING AND COAL TAR DISTILLATION WORLD BANK GROUP concentration of SO2 to allow direct processing to H2SO4. The The second types of processes, known as wet processes, are thermal oxidizing process of spent acids used as raw materials those digesting phosphate rocks with an acid (i.e. sulfuric, nitric is another route to produce SO2 and H2SO4. The exothermic or hydrochloric acid). The wet digestion of phosphate rock with oxidation of sulfur dioxide over several layers of a suitable sulfuric acid is the preferred process in term of volume. The tri- catalyst (i.e., vanadium pentoxide) to produce sulfur trioxide calcium phosphate from the phosphate rock reacts with (SO3) is the process used today in almost all sulfuric acid concentrated sulfuric acid to produce phosphoric acid and manufacturing plants. Modern plants can be designed to be very calcium sulfate that is an insoluble salt. The operating efficient in terms of sulfur dioxide conversion (more than 99%) conditions are generally selected so that the calcium sulfate is and energy recovery. precipitated as the dihydrate (DH) or hemihydrate (HH) form. Sulfuric acid is obtained from the absorption of SO3 and water The main production steps are the fo llowing: grinding of into H2SO4 (with a concentration of at least 98%). SO3 is phosphate rock; reaction with sulfuric acid in a series of absorbed in an intermediate absorber installed after the second separate agitated reactors at a temperature of 70-80 °C; and or third catalyst layer in a double contact process, where the filtration to separate the phosphoric acid from the calcium gases are then conveyed to the final catalyst layer(s) and the sulfate. SO3 formed here is absorbed in a final absorber. The final Phosphoric acid is most commonly stored in rubber-lined steel absorber is installed after the last catalyst layer in a single tanks, although stainless steel, polyester and polyethylene-lined contact process. The warm acid produced is sparged with air in concrete are also used. Storage tanks are normally equipped a column or in a tower to collect the remaining SO2 in the acid; with some means of keeping the solids in suspension to avoid the SO2 laden air is returned to the process. costly cleaning of the tank. Phosphoric Acid35 Hydrofluoric Acid 36 Phosphoric acid (H3PO4) is primarily used in the manufacture of Hydrogen fluoride (HF) is produced in two forms, as anhydrous phosphate salts (fertilizers and animal feed supplements). Two hydrogen fluoride and as aqueous hydrofluoric acid. The different processes can be used in the manufacture of predominant form manufactured is hydrogen fluoride, a phosphoric acid. In the first process, known as the thermal colorless liquid or gas that fumes when in contact with air and is process, elemental phosphorus is produced from phosphate water-soluble. Hydrogen fluoride is also a fortuitous by-product rock, coke and silica in an electrical resistance furnace and is in the manufacture of superphosphate fertilizers. Hydrofluoric then oxidized and hydrated to form the acid. Thermal-generated acid is used in glass etching and polishing, petroleum alkylation, acid is considerably pure, but also expensive, and hence and stainless steel pickling. Hydrofluoric acid is also used to produced in small quantities, mainly for the manufacture of produce fluorocarbons for the manufacture of resins, solvents, industrial phosphates. stain removers, surfactants, and pharmaceuticals. 35 EIPPCB. 2006b; EFMA. 2000d 36 EIPPCB. 2006b DECEMBER 10, 2007 24 Environmental, Health, and Safety Guidelines LARGE VOLUME INORGANIC COMPOUNDS MANUFACTURING AND COAL TAR DISTILLATION WORLD BANK GROUP Hydrofluoric acid is manufactured by the reaction of acid-grade condense the evaporating HF. Liquid HF is normally stored at fluorspar (CaF2) with sulfuric acid (H2SO4). The endothermic atmospheric pressure in carbon steel tanks, where a thin reaction is conducted in horizontal rotary kilns externally heated protective layer of FeF2 is formed, preventing the tank walls from to 200 to 250°C. Dry fluorspar and a slight excess of sulfuric fur ther corrosion. Liquid velocity in the pipelines should be acid are fed continuously to the front end of a stationary pre- below 1 m/s to avoid erosion of the FeF2 layer. Hydrofluoric acid reactor for mixing or directly to the kiln by a screw conveyor. with a concentration of at least 70 % is also stored in carbon Calcium sulfate (CaSO4) is removed through an air lock at the steel tanks, whereas acid with concentrations of less than 70 % opposite end of the kiln. is stored in lined steel tanks or alternatively in polyethylene tanks. The gaseous reaction products - hydrogen fluoride and excess H2SO4 from the primary reaction, and silicon tetrafluoride (SiF 4), Hydrochloric Acid37 sulfur dioxide (SO2), carbon dioxide (CO2), and water vapor Hydrochloric acid (HCl) is a versatile chemical used in a variety produced in secondary reactions - are removed from the front of chemical processes, including hydrometallurgical processing, end of the kiln along with entrained particulate matter. The chlorine dioxide syntheses, hydrogen production, and particulate matter is then removed from the gas stream and miscellaneous cleaning and etching operations. It is also a returned to the kiln. Sulfuric acid and water are removed in a common ingredient in many chemical reactions, and a pre-condenser. Hydrogen fluoride vapors are subsequently commonly used acid for catalyzing organic processes. condensed in refrigerant condensers forming crude HF, which is sent to intermediate storage tanks. The remaining gas stream The acid is manufactured by several different processes. passes through a sulfuric acid absorption tower or acid commonly applied production processes consist of reacting scrubber, removing most of the remaining hydrogen fluoride and sodium chloride with sulfuric acid, or more recently, the acid is some residual sulfuric acid, which are also sent to intermediate generated as a by-product of the chlorination reaction process storage. The gases exiting the acid scrubber are treated in (e.g., production of chlorinated solvents and organics). water scrubbers, where both SiF 4 and remaining HF are recovered as hexafluorosilicic acid (H2SiF 6). The water scrubber Chlor-alkali38 tail-gases are passed through a caustic scrubber before being The chlor-alkali industry produces chlorine (Cl2) and alkali (i.e., emitted to the atmosphere. The hydrogen fluoride and sulfuric caustic soda or sodium hydroxide (NaOH) and potassium acid are delivered from intermediate storage tanks to distillation hydroxide (KOH)), by electrolysis of a salt solution, mainly using columns, where the hydrofluoric acid is extracted at 99.98 sodium chloride (NaCl) as feed or potassium chloride (KCl) for percent purity. A final dilution step with water is needed to the production of potassium hydroxide. The chlor-alkali process produce weaker concentrations (typically 70 to 80 per cent). is an important consumer of electrical energy. Anhydrous HF is a liquid which boils at 19.5 °C. The liquid HF is kept at low temperature, preferably below 15 °C, by cooling or 37 Australian Government, Department of the Environment and Heritage. 2004. by the installation of condensers in vent storage pipelines which 38 EIPPCB. 2001. DECEMBER 10, 2007 25 Environmental, Health, and Safety Guidelines LARGE VOLUME INORGANIC COMPOUNDS MANUFACTURING AND COAL TAR DISTILLATION WORLD BANK GROUP The main chlor-alkali manufacturing technologies are mercury, The cathode material used in membrane cells is either stainless diaphragm and membrane cell electrolysis. In the chlorine steel or nickel and the anodes used are metal. The cathodes are process, chlorine gas leaving the electrolyzers is at often coated with a catalyst that increases surface area and approximately 80-90 ºC and saturated with water vapor. It also reduces over-voltage. Coating materials include Ni-S, Ni- Al, and contains impurities such as brine mist, nitrogen, hydrogen, Ni-NiO mixtures, as well as mixtures of nickel and platinum oxygen, carbon dioxide and traces of chlorinated hydrocarbons. group meta ls. The membranes used in the chlor-alkali industry After direct or indirect cooling and impurities removal, chlorine is are commonly made of perfluorinated polymers. passed to the drying towers for drying with concentrated sulfuric Chlorine is often produced near consumers. Storage and acid. The gas is then compressed and liquefied at different transport of chlorine requires proper handling and use of best pressure and temperature levels. Liquefied chlorine is stored in bulk tanks at ambient or low temperature. practice to minimize potential hazards. Chlorine is transported by pipe, road and rail. The membrane cell process has environmental advantages over Hydrogen is a co-product of the electrolysis of brine (28 kg for 1 the two older processes, in addition to be currently the most tonne of chlorine) and is generally used on-site as a economically advantageous process. The anode and cathode combustible, sent as a fuel to other companies, or sold and are separated by a water-impermeable ion-conducting transported as chemical. It can be used on integrated sites for membrane. Brine solution flows through the anode compartment certain applications because of its high purity, including where chloride ions are oxidized to chlorine gas. The sodium synthesis of ammonia, methanol, hydrochloric acid, hydrogen ions migrate through the membrane to the cathode peroxide, etc. compartment which contains caustic soda solution. The demineralized water added to the catholyte circuit is hydrolyzed, In addition to cell electrolysis, there are processing steps which and releases hydrogen gas and hydroxide ions. The sodium and are common to all technologies and include: salt unloading and hydroxide ions combine to produce caustic soda which is storage, brine purification and resaturation, chlorine, caustic typically brought to a concentration of 32-35% by recirculating soda, and hydrogen processing. the solution before discharge from the cell. Higher concentrations are produced concentrating the caustic liquor by The brine purification process consists of a primary system for steam evaporation. The output of caustic soda is proportional to the mercury and diaphragm technologies and an additional that of chlorine (1.128 tonnes of caustic soda (100%) are secondary system for membrane technology. This operation is produced by electrolysis per tonne of chlorine). Because of the needed to eliminate impurities (sulfate anions, cations of membrane, the caustic soda solution contain a very limited calcium, magnesium, barium and metals) that can affect the amount of salt due to migration of chloride, as in the diaphragm electrolytic process. cell process. Depleted brine is discharged from the anode compartment and resaturated with salt. The primary brine purification uses sodium carbonate and sodium hydroxide to precipitate calcium and magnesium ions as calcium carbonate (CaCO3) and magnesium hydroxide DECEMBER 10, 2007 26 Environmental, Health, and Safety Guidelines LARGE VOLUME INORGANIC COMPOUNDS MANUFACTURING AND COAL TAR DISTILLATION WORLD BANK GROUP (Mg(OH)2). Metals may also precipitate as hydroxide during this Soda ash is generally manufactured by large, highly integrated operation. Sodium sulfate may be controlled by adding calcium production units, with a plant capacity ranging from 150 to 1,200 chloride (CaCl2) or barium salts (which however may represent kt per year. a hazard due to their toxicity) to remove sulfate anions by The Solvay process (ammonia soda process) involves precipitation of calcium sulfate (CaSO4) or barium sulfate saturation of brine with ammonia and carbon dioxide gas. The (BaSO4). After precipitation, impurities are removed by process uses salt brine (NaCl) and limestone (CaCO3) as raw sedimentation, filtration or a combination of both. Other materials. Ammonia is almost totally regenerated and recycled. possibilities to remove sulfates include ultra-filtration and brine The main advantage of this process is the widespread purging. availability of the relatively pure raw materials, which allow The secondary brine purification consists of a polish filtration operating production units relatively close to the market. step and brine softening in an ion exchange unit generally with The Solvay process produces ‘light soda ash’, with a pouring filters in order to sufficiently reduce the suspension matter and density of about 500 kg/m3. ‘Light soda ash’ is transformed by protect the ion-exchange resin from damage. The ion exchange recrystallization first to sodium carbonate monohydrate, and chelating resin treatment is designed to decrease the alkaline then to ‘dense soda ash’ after drying (dehydration). Dense soda earth metals to trace levels. The resin is periodically ash has a pouring density of about 1,000 kg/m3. Dense soda regenerated with high purity hydrochloric acid and sodium ash can also be produced by compaction. hydroxide solutions. Instead of diluting the remaining gases after partial Carbon Black40 condensation of the chlorine gas, the hydrogen is removed by Carbon black is produced by partial oxidation or thermal means of a reaction with chlorine gas in a column. This step decomposition of hydrocarbons. About 65 – 70 % of the world’s produces gaseous hydrochloric acid, which can be recovered in consumption of carbon black is used in the production of tires a hydrochloric acid unit. and tire products for automobiles and other vehicles. Roughly 25 - 30% is used for other rubber products and a small percent Soda Ash39 is used in plastics, printing ink, paint, paper and miscellaneous Sodium carbonate (Na2CO3) or soda ash is a fundamental raw applications. material to the glass, soaps and detergents, and chemicals Carbon black differs from other carbon-based materials in many industries. Soda ash (calcined soda) is manufactured in two respects, especially in bulk density. Mixtures of gaseous or grades: ‘light soda ash’ and ‘dense soda ash’. Dense soda ash liquid hydrocarbons represent the raw materials preferable for is mainly used in the glass industry and for economic industrial production with preference to aromatic hydrocarbons transportation over long distances. The light form is used mainly for better yields. for the detergent market and certain chemical intermediates. 39 EIPPCB. 2006a. 40 EIPPCB. 2006a. DECEMBER 10, 2007 27 Environmental, Health, and Safety Guidelines LARGE VOLUME INORGANIC COMPOUNDS MANUFACTURING AND COAL TAR DISTILLATION WORLD BANK GROUP The processes are divided into two groups: those employing groups, and to a lesser extent their sulfur-, nitrogen-, and incomplete or partial combustion and those based on thermal oxygen-containing analogues. Tars produced at the lower coal cracking. In the partial combustion processes, air is used to burn carbonization temperatures also contain hydroaromatics, part of the feedstock, producing the energy required to carry out alkanes, and alkenes. The residue from the distillation is at least the pyrolysis, whereas in the thermal cracking process, heat is 50% of the coal tar products by high temperature carbonization generated externally and introduced into the process. and consists of a continuation of the sequence of polynuclear aromatic, aromatic, and heterocyclic compounds, up to The furnace black process is currently the most important molecules containing 20 to 30 rings. production process. It accounts for more than 95% of the to tal worldwide production. It is a continuous process and its Metal corrosion associated to continuous coal tar distillation is a advantages are its great flexibility and its better economy typical issue to be considered in plant management. The compared to other process. The typical production rate is ammonium salts (mainly ammonium chloride), associated with approximately 2,000 kg/h for a modern furnace black reactor. In the entrained liquor remain in the tar after dehydration, tend to furnace black, a heavy aromatic feedstock is injected by dissociate with the production of hydrochloric acid. This acid atomization into a high speed stream of combustion gases and may deteriorate any equipment parts in which these vapors and partially burned and mostly cracked (45 – 65%) to produce steam are present above 240°C, including the condensers on carbon black and hydrogen at a te mperature ranging from 1200 the dehydration and fractionation columns. Corrosion is to 1700° C. After quenching with water, carbon black is controlled by the addition of alkali (either sodium carbonate recovered by cyclones and bag filters, pellettized, dried and solution or caustic soda) to the tar. delivered to storage (silos) or shipped. A primary distillation product pattern at a tar-processing plant Coal Tar Distillation can give only one fraction, naphthalene oil taken between 180 and 240°C, or two fractions, light creosote or middle oil (230– Coal tar is currently almost totally distilled mainly in continuous 300°C) and heavy creosote or heavy oil (above 300°C) between stills that have daily capacities of 100–700 tons. It is a the naphthalene oil and pitch. condensation product obtained by cooling the gas evolved in coal distillation (pyrolysis or carbonization of coal). Coal tar is a The higher boiling cresylic acids are mixtures of cresols or black viscous liquid denser than water. Coal- tar pitch is a black xylenols with higher boiling phenols. Their main uses are in very viscous, semisolid, or solid residue from the distillation of phenol- formaldehyde resins, solvents for wire-coating enamels, coal tar. metal degreasing agents, froth-flotation agents, and synthetic tanning agents. The coal tar product, which distills up to about 400°C at atmospheric pressure, is primarily a complex mixture of mono- Naphthalene is the principal component of coke-oven tars and and polycyclic aromatic hydrocarbons, a proportion of which are the only component that can be concentrated to a reasonably substituted with alkyl, hydroxyl, amine and/or hydro sulfide DECEMBER 10, 2007 28 Environmental, Health, and Safety Guidelines LARGE VOLUME INORGANIC COMPOUNDS MANUFACTURING AND COAL TAR DISTILLATION WORLD BANK GROUP high content on primary distillation 41. Naphthalene oils can be further upgraded by several methods, mainly based on crystallization of the primary naphthalene oil to upgrade to phthalic grade quality or to convert the latter into the purer chemical grade anthracene oils. Naphthalene has been traditionally used for the production of phthalic anhydride, ß- naphthol and dye stuff intermediates. More recently, naphthalene has been used in condensation products from naphthalene sulfonic acids, utilizing formaldehyde as additives to improve the flow properties of concrete. Another application is the production of diisopropylnaphthalenes. Crude anthracene is isolated from coke-oven anthracene oils. Where the anthracene oil gives only a limited residue at 360°C, the oil is diluted using naphthalene drained oil or a light wash oil and this blend is cooled to 35°C. The resulting solid–liquid slurry is filtered or centrifuged to give a crude anthracene oil containing 40–45% anthracene. The recovery of tar chemicals leaves residual oils, including heavy naphtha, dephenolated carbolic oil, naphthalene drained oil, wash oil, strained anthracene oil, and heavy oil. These are blended to give creosote oils, which have been used as timber preservatives Coal-tar creosote is also a feedstock for carbon black manufacture. Other smaller markets for creosote are for fluxing coal tar, pitch, and bitumen. 41Naphthalene oils from coke-oven tars generally contain 60–65% of naphthalene. DECEMBER 10, 2007 29