Environmental, Health, and Safety Guidelines PETROLEUM-BASED POLYMERS MANUFACTURING WORLD BANK GROUP Environmental, Health and Safety Guidelines for Petroleum-based Polymers Manufacturing Introduction specific variables, such as host country context, assimilative capacity of the environment, and other project factors, are The Environmental, Health, and Safety (EHS) Guidelines are taken into account. The applicability of specific technical technical reference documents with general and industry- recommendations should be based on the professional opinion specific examples of Good International Industry Practice of qualified and experienced persons. (GIIP) 1. When one or more members of the World Bank Group are involved in a project, these EHS Guidelines are applied as When host country regulations differ from the levels and required by their respective policies and standards. These measures presented in the EHS Guidelines, projects are industry sector EHS guidelines are designed to be used expected to achieve whichever is more stringent. If less together with the General EHS Guidelines document, which stringent levels or measures than those provided in these EHS provides guidance to users on common EHS issues potentially Guidelines are appropriate, in view of specific project applicable to all industry sectors. For complex projects, use of circumstances, a full and detailed justification for any proposed multiple industry-sector guidelines may be necessary. A alternatives is needed as part of the site-specific environmental complete list of industry-sector guidelines can be found at: assessment. This justification should demonstrate that the www.ifc.org/ifcext/enviro.nsf/Content/EnvironmentalGuidelines choice for any alternate performance levels is protective of human health and the environment The EHS Guidelines contain the performance levels and measures that are generally considered to be achievable in new Applicability facilities by existing technology at reasonable costs. Application These guidelines are applicable to petroleum-based polymer of the EHS Guidelines to existing facilities may involve the establishment of site-specific targets, with an appropriate manufacturing where monomers are polymerized and finished into pellets or granules for subsequent industrial use.2 timetable for achieving them. This document is organized according to the following sections: The applicability of the EHS Guidelines should be tailored to the hazards and risks established for each project on the basis Section 1.0 — Industry-Specific Impacts and Management of the results of an environmental assessment in which site- Section 2.0 — Performance Indicators and Monitoring Section 3.0 — References and Additional Sources Annex A — General Description of Industry Activities 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 circumstances globally. The circumstances that skilled and experienced professionals may find when evaluating the range of pollution prevention and control techniques available to a project may include, but are not limited to, varying levels of environmental degradation and environmental assimilative 2 Elastomer manufacturing plants and fiber manufacturing plants are not capacity as well as varying levels of financial and technical feasibility. included in the scope of this Guideline. APRIL 30, 2007 1 Environmental, Health, and Safety Guidelines PETROLEUM-BASED POLYMERS MANUFACTURING WORLD BANK GROUP 1.0 Industry-Specific Impacts • Condensing VOCs at low temperature or in adsorption beds, before venting exhaust air. Drying should recycle and Management exhaust air or nitrogen, with VOC condensation; The following section provides a summary of EHS issues • Use of closed-loop nitrogen purge systems, use of associated with polymer manufacturing, along with degassing extruders, and collection of off-gases from recommendations for their management. Recommendations for extrusion in polyolefin plants due to the fire hazard related the management of EHS issues common to most large industrial to the flammability of the hydrocarbons and to the high facilities during the construction and decommissioning phase(s) temperatures involved; are provided in the General EHS Guidelines. • Vent gases emitted from reactors, blow-down tanks, and 1.1 Environmental strippers containing significant levels of VCM should be collected and purified prior to emission to atmosphere. Potential environmental issues associated with polymer Water that has significant levels of VCM, for example water manufacturing projects include: used for the cleaning of reactors containing VCM, transfer lines, and suspension or latex stock tanks, should be • Air emissions passed through a stripping column to remove VCM in • Wastewater polyvinyl chloride manufacturing using the suspension • Hazardous materials process; • Wastes • Use of stripping columns specifically designed to strip • Noise suspensions in polyvinyl chloride manufacturing using the suspension process; Air Emissions • Production of stable latexes and use of appropriate Volatile Organic Compounds (VOCs) from Drying and Finishing stripping technologies in emulsion polyvinyl chloride plants, The most typical air emissions from polymer plants are volatile which combine emulsion polymerization and open cycle organic compound (VOC) emissions from drying and finishing, spray drying; and purging. Recommended measures to control VOC in drying • Multistage vacuum devolatilization of molten polymer to and finishing operations include the following: reduce the residual monomer at low levels4,5 in polystyrene and generally in styrenic polymers manufacturing;6 • Separation and purification of the polymer downstream to • Spill and leak prevention in acrylic monomer emulsion the reactor; 3 polymerization, due to the very strong, pungent, low- • Flash separation of solvents and monomers; threshold odor of all acrylic monomers 7; • Steam or hot nitrogen stripping; • Degassing stages in extruders, possibly under vacuum; 4 EU Commission Directive 2002/72/EC and following amendments. 5 Food, Drug and Cosmetic Act as amended under Food Additive Regulation 21 CFR §. 6 This situation may occur due to the relatively low volatility of the monomer 3The removal effectiveness is dependent on various factors including the (styrene) or solvent (ethylbenzene) compared to the low concentrations required volatility of the VOC, the properties of the polymer, and the type of in the process (e.g. for food application products). polymerization process. 7 US EPA Technology Transfer Network, Air Toxics Website, Ethyl acrylate APRIL 30, 2007 2 Environmental, Health, and Safety Guidelines PETROLEUM-BASED POLYMERS MANUFACTURING WORLD BANK GROUP • Treatment of waste gases by catalytic oxidation or accepted standards, or by thermic/catalytic oxidation, prior equivalent techniques in polyethylene terephthalate to emission to the atmosphere; manufacturing; • In High Impact Polystyrene Sheets (HIPS) manufacture, air • Wet scrubbing of vents in polyamide manufacturing; emissions from polybutadiene dissolution systems should • Catalytic or thermal treatment of gaseous and liquid wastes be minimized by use of continuous systems, vapor balance in all thermoset polymer manufacturing; lines, and vent treatment; • Installation of closed systems, with vapor condensation and • In unsaturated polyester and alkyd resins units, waste gas vent purification, in phenol-formaldehyde resins streams generated from process equipment should be manufacturing, due to the high toxicity of both main treated by thermal oxidation or, if emissions concentrations monomers; and permit, by activated carbon adsorption; • VOCs from the finishing sections and reactor vents should • Use glycol scrubbers or sublimation boxes for anhydride be treated through thermal and catalytic incineration vapor recovery from unsaturated polyester and alkyd resins techniques before being discharged to the atmosphere. storage tank vents; For chlorinated VOCs, incineration technology should • In phenolic resins production, VOC contaminated process ensure the emission levels of dioxins / furans meet the limit emissions, especially from reactor vents, should be stated in Table 1. recovered or incinerated; • In aliphatic polyamide manufacturing, use wet scrubbers, VOCs from Process Purges condensers, activated carbon adsorbers, together with Process purges are associated with purification of raw materials, thermal oxidation. filling and emptying of reactors and other equipment, removal of reaction byproducts in polycondensation, vacuum pumps, and VOCs from Fugitive Emissions depressurization of vessels. Recommended pollution Fugitive emissions in polymer manufacturing facilities are mainly prevention and control measures include the following: associated with the release of VOCs from leaking piping, valves, connections, flanges, packings, open-ended lines, floating roof • Process vapors purges should be recovered by storage tanks and seals, pump seals, gas conveyance systems, compression or refrigeration and condensation of compressor seals (e.g. ethylene and propylene compressors), liquefiable components or sent to a high efficiency flare pressure relief valves, loading and unloading operations of raw system that can ensure efficient destruction; materials and chemicals (e.g. cone roof tanks), preparing and • The incondensable gases should be fed to a waste-gas blending of chemicals (e.g. preparation of solutions of burning system specifically designed to ensure a complete polymerization aids and polymer additives), and waste water combustion with low emissions and prevention of dioxins treatment units (WWTUs). The process system should be and furans formation; designed to minimize fugitive emissions of toxic and • In polyvinyl chloride (PVC) plants, VCM-polluted gases (air hydrocarbon gases. General VOC and fugitive emissions and nitrogen) coming from VCM recovery section should guidance is provided in the General EHS Guidelines. be collected and treated by VCM absorption or adsorption, Recommended industry-specific measures include: by incineration techniques following internationally APRIL 30, 2007 3 Environmental, Health, and Safety Guidelines PETROLEUM-BASED POLYMERS MANUFACTURING WORLD BANK GROUP • In polyethylene manufacturing, monomer leakages from through scrubbing and high-efficiency flaring. Industry-specific reciprocating compressors used in high-pressure measures include the following: polyethylene plants should be recovered and recycled to the low pressure suction stage; • Ethylene vented from high-pressure low density polyethylene (LDPE) and linear low density polyethylene • In polyvinyl chloride manufacture, opening of reactors for (LLDPE) plants, cannot be conveyed to the flare due to maintenance should be minimized and automatic cleaning opening of the reactor safety disks at high pressures, but systems should be adopted. should be vented to the atmosphere through a stack, after Particulate Matter having been diluted with steam and cooled by water Emissions of particulate matter (i.e. polymer fines and/or scrubbing to minimize risks of explosive clouds. additives as antistick agents, etc.) are associated with polymer Specifically designed systems operated by detonation drying and packaging operations. Other sources of particulate sensors should be used; mater include pellet conveyance, transfer, and dedusting. • Pressure Safety Valves (PSV) should be used in Recommended particulate matter management measures polymerization plants to reduce the amount of chemicals include: released from an overpressure/relief device activation, where release is directly to the atmosphere; • Optimization of dryer design; • Because of the possibility of pipe plugging by polymer • Use of gas closed loop; formation, redundant safety systems are recommended, • Reduction at source (e.g. granulation transfer systems) and with frequent and proper inspection. PSV lines should be capture via elutriation facilities; protected upstream by PSDs, to avoid losses and plugging. • Installation of electrostatic precipitators, bag filters or wet Fittings should be provided to enable check of safety scrubbing; systems during plant operation; • Installation of automatic bagging systems and efficient • In polyvinyl chloride manufacturing, the occurrence of ventilation in packaging operations; emergency venting from the polymerization reactors to • Good housekeeping. atmosphere due to runaway reaction should be minimized by one or more of the following techniques: Venting and Flaring o Specific control instrumentation for reactor feed and Venting and flaring are important safety measures used in operational conditions, polymer manufacturing facilities to ensure all process gases, o Chemical inhibitor system to stop the reaction, coming from storage as well from process units, are safely o Emergency reactor cooling capacity, disposed off in the event of a safety disk or valve opening, o Emergency power for reactor stirring, and emergency, power or equipment failure, or other plant upset o Controlled emergency venting to VCM recovery conditions. Emergency discharges from reactors and other system.8 critical process equipment should be conveyed to blow-down tanks, where the reactants are recovered (e.g. by steam or vacuum stripping) before discharging the treated wastes, or 8 EIPPCB BREF (2006) APRIL 30, 2007 4 Environmental, Health, and Safety Guidelines PETROLEUM-BASED POLYMERS MANUFACTURING WORLD BANK GROUP • Where foaming occurs during emergency venting, it should stress. Additional areas with potential opportunities for reduction be reduced by antifoam addition, to avoid plugging of in energy consumption include dewatering systems, closed loop venting system; cooling water systems, inert gas close loop drying, use of low • During emergency venting, the content of the reactor shear extruders for compounding, increase of polymer should be discharged to a blow-down tank and steam concentration, and gear pumps for pelletizing. stripped before disposal; • In acrylic latexes manufacturing, emergency venting to Acid Gases flare system from reactors due to runaway polymerization Hydrogen chloride (HCl) traces, originated from the hydrolysis of should be prevented by one or more of the following: chlorinated organic compounds by the catalyst, can be present o Continuous computer controlled addition of reactants in exhaust air from drying of polymers produced by ionic to the reactor, based on actual polymerization kinetics, catalysis. Although acid is usually present at low level, gas o Chemical inhibitor system to stop the reaction, stream testing is recommended and pollution control measures, o Emergency reactor cooling capacity, such as wet scrubbing, should be considered if levels become o Emergency power for reactor stirring, and significant. o Discharge of reactor content to a blow-down tank. Dioxins and Furans Combustion Sources and Energy Efficiency Gaseous, liquid, and solid waste incineration plants are typically Polymerization plants consume large quantities of energy and present as one of the auxiliary facilities in polymer steam, which are typically produced on site in cogeneration manufacturing plants. The incineration of chlorinated organic facilities. Emissions related to the operation of power sources compounds (e.g. chlorophenols) could generate dioxins and should be minimized through the adoption of a combined furans. Certain catalysts in the form of transition metal strategy which includes a reduction in energy demand, use of compounds (e.g. copper) also facilitate the formations of dioxins cleaner fuels, and application of emissions controls where and furans. Recommended prevention and control strategies required. Recommendations on energy efficiency are include: addressed in the General EHS Guidelines. • Operation of incineration facilities according to Polymerization plants operate in a wide range of conditions internationally recognized technical standards;9 (temperature and pressure) and it is usually possible and useful • Maintaining proper operational conditions, such as to include a temperature or energy cascade in their design to sufficiently high incineration and flue gas temperatures, to recover heat (e.g. low pressure steam for stripping or heating prevent the formation of dioxins and furans; purposes) and compression energy. The correct choice and • Ensuring emissions levels meet the guideline values design of the purification operations according to their presented in Table 2. thermodynamic efficiency is a major component in reduction of energy requirements. Drying and finishing of polymers are important aspects to consider, because of their energy demand and because polymers are sensitive to heat and mechanical 9For example, Directive 2000/76/EC of the European Parliament and of the Council of 4 December 2000 on the incineration of waste. APRIL 30, 2007 5 Environmental, Health, and Safety Guidelines PETROLEUM-BASED POLYMERS MANUFACTURING WORLD BANK GROUP Wastewater polymerization catalysts (e.g., Li, Ni, Co, V, etc) should be Industrial Process Wastewater pre-treated as needed prior to discharge to the facility’s wastewater treatment system; Process wastewater from plant units may contain hydrocarbons, monomers and other chemicals, polymers and other solids • Spent reactant solutions should be sent to specialized (either suspended or emulsified), surfactants and emulsifiers, treatment for disposal; oxygenated compounds, acids, inorganic salts, and heavy • Acidic and caustic effluents from demineralized water metals. preparation should be treated by neutralization prior to discharge to the facility’s wastewater treatment system; Recommended wastewater management strategies include the • Contaminated water from periodic cleaning activities during following: facility turn-arounds should be tested and treated in the facility’s wastewater treatment system; • Wastewater containing volatile monomers (e.g., VCM, • Oily effluents, such as process leakages, should be styrene, acrylonitrile, acrylic esters, vinyl acetate, collected in closed drains, decanted and discharged to the caprolactam) and/or polymerization solvents (e.g., facility’s wastewater treatment system; condensate from steam stripping of suspensions or • Facilities should prepare and implement hazardous latexes, condensate from solvent elimination, or materials management program, including specific spill wastewater from equipment maintenance) should be prevention and control plans, according to the recycled to the process where possible, or otherwise recommendations provided in the General EHS treated by flash distillation or equivalent separation to Guidelines ; remove VOC, prior to conveying it to the facility’s • Sufficient process fluids let-down capacity should be wastewater treatment system; provided to avoid process liquid discharge into the oily • Organics should be separated and recycled to the process, water drain system and to maximize recovery into the when possible, or incinerated; process. • Non-recyclable contaminated streams, such as wastewater originated from polyester or from thermoset polymer Process Wastewater Treatment manufacturing, should be catalytically or thermally Techniques for treating industrial process wastewater in this incinerated; sector include source segregation and pretreatment of • Emulsion and suspension polymerization aids should be concentrated wastewater streams. Typical wastewater treatment selected with consideration of their biodegradability, as steps include: grease traps, skimmers, dissolved air floatation or they enter the wastewater stream during polymer recovery; oil water separators for separation of oils and floatable solids; • Whenever less biodegradable or non-biodegradable filtration for separation of filterable solids; flow and load polymerization aids are used, a specifically designed water equalization; sedimentation for suspended solids reduction pre-treatment unit should be installed prior to discharge to using clarifiers; biological treatment, typically aerobic treatment, the facility’s wastewater treatment system; for reduction of soluble organic matter (BOD); chlorination of • Wastewater originated from polymer recovery after ionic effluent when disinfection is required; dewatering and disposal polymerization and containing metal ions from of residuals in designated hazardous waste landfills. APRIL 30, 2007 6 Environmental, Health, and Safety Guidelines PETROLEUM-BASED POLYMERS MANUFACTURING WORLD BANK GROUP Additional engineering controls may be required for (i) and transport, as well as issues associated with Ozone containment and treatment of volatile organics stripped from Depleting Substances (ODSs) are presented in the General various unit operations in the wastewater treatment system, EHS Guidelines . (ii)advanced metals removal using membrane filtration or other physical/chemical treatment technologies, (iii) removal of Wastes recalcitrant organics and non biodegradable COD using Storage and handling of hazardous and non-hazardous wastes activated carbon or advanced chemical oxidation, (iii) reduction should be conducted in a way consistent with good EHS in effluent toxicity using appropriate technology (such as reverse practice for waste management, as described in the General osmosis, ion exchange, activated carbon, etc.), and (iv) EHS Guideline. Industry-specific hazardous wastes include containment and neutralization of nuisance odors. waste solvents and waste oil spent catalysts, saturated filtering beds, and solid polymer wastes from polymerization plants.10 Management of industrial wastewater and examples of treatment approaches are discussed in the General EHS Spent Catalysts Guidelines . Through use of these technologies and good Spent catalysts are originated from catalyst bed replacement in practice techniques for wastewater management, facilities scheduled turnarounds of monomer purification reactors (e.g. should meet the Guideline Values for wastewater discharge as hydrogenation of impurities in lower olefins) or less frequently, in indicated in the relevant table of Section 2 of this industry sector heterogeneous polymerization catalysis. Spent catalysts can document. contain nickel, platinum, palladium, and copper, depending on the process. Recommended management strategies for spent Other Wastewater Streams & Water Consumption catalysts include the following: Guidance on the management of non-contaminated wastewater from utility operations, non-contaminated stormwater, and • Appropriate on-site management, including submerging sanitary sewage is provided in the General EHS Guidelines. pyrophoric spent catalysts in water during temporary Contaminated streams should be routed to the treatment system storage and transport until they can reach the final point of for industrial process wastewater. Stormwater collection and treatment to avoid uncontrolled exothermic reactions; treatment may usually entail collection of runoff from paved • Return to the manufacturer for regeneration, or off-site areas and treatment through a skimmer pit to recover spilled management by specialized companies that can either resin. Recommendations to reduce water consumption, recover the heavy or precious metals, through recovery especially where it may be a limited natural resource, are and recycling processes whenever possible, or manage provided in the General EHS Guidelines. spent catalysts according to hazardous and non-hazardous waste management recommendations presented in the Hazardous Materials General EHS Guidelines. Catalysts that contain platinum Polymer manufacturing facilities use and store significant or palladium should be sent to a noble metals recovery amounts of hazardous materials, including intermediate / final facility. products and by-products. Recommended practices for 10Refer to section on dioxins and furans for emissions-related guidance hazardous material management, including handling, storage, applicable to incineration of chlorinated organic wastes. APRIL 30, 2007 7 Environmental, Health, and Safety Guidelines PETROLEUM-BASED POLYMERS MANUFACTURING WORLD BANK GROUP Saturated Filtering Beds Noise Saturated filtering beds originate from solution polymerization Significant noise sources in polymer manufacturing facilities processes, for example, from removal of spent polymerization include activities involving physical processing of polymers (e.g., catalysts from the polymer solution or in a number of screening, grinding, pneumatic conveying), as well as large deodorization or clarification operations. Recommended rotating machines, such as extruders, compressors and management strategies for saturated filtering beds include turbines, pumps, electric motors, fans, air coolers. During minimizing purification agents through online regeneration and emergency depressurization, high noise levels can be extended lifetime, proper containment during temporary storage generated due to high pressure gases to flare and/or steam and transport, and off-site management by specialized release into the atmosphere. Recommendations for noise companies. management are provided in the General EHS Guidelines . Solid Polymer Wastes 1.2 Occupational Health and Safety Polymer wastes are produced during normal plant operation The occupational health and safety issues that may occur during (e.g., latex filtering and sieving, powder screening and granule the construction and decommissioning of polymer grinding); campaign changes; start-up; and maintenance and manufacturing facilities are similar to those of other industrial emergency shutdowns of polymer processing equipment. facilities, and their management is discussed in the General Recommended pollution prevention and control measures EHS Guidelines. include the following: Facility-specific occupational health and safety issues should be • Recycling or re-use of waste streams where possible identified based on job safety analysis or comprehensive hazard instead of disposal. Possible recycling options include sale or risk assessment, using established methodologies such as a of waxes to wax industry; hazard identification study [HAZID], hazard and operability study [HAZOP], or a quantitative risk assessment [QRA]. As a general • Treatment as necessary to remove and separately recover approach, health and safety management planning should VOCs (e.g. by steam stripping); include the adoption of a systematic and structured approach for • Segregation and storage in a safe location. Some polymer prevention and control of physical, chemical, biological, and wastes (e.g. heat or shear stressed polymers produced radiological health and safety hazards described in the General during start or stop operations of drying and finishing EHS Guidelines . The most significant occupational health and equipment, oxidized polymer recovered during dryer safety hazards occur during the operational phase of polymer maintenance, process plant crusts without antioxidants, manufacturing and primarily include: and aged polymer wastes) might be unstable and prone to self-heating and self-ignition. Such waste should be stored • Process Safety in a safe manner and disposed of (e.g., incinerated) as • Fires and Explosions soon as practical. • Other chemical hazards • Confined spaces APRIL 30, 2007 8 Environmental, Health, and Safety Guidelines PETROLEUM-BASED POLYMERS MANUFACTURING WORLD BANK GROUP Process Safety • Product decomposition in tubular reactors should be Process safety programs should be implemented due to prevented through heat transfer, temperature profile industry-specific characteristics, including complex chemical control, high speed flow and good pressure control; reactions, use of hazardous materials (e.g., toxic and reactive • Explosion of high pressure separators should be prevented materials and flammable or explosive compounds), and multi- by vessel reactors design measures, careful dosing of step reactions. Process safety management includes the peroxides, control of polymerization temperature, rapid following actions: detection of uncontrolled exothermic reactions and rapid isolation / depressurizing, and good maintenance of • Physical hazard testing of materials and reactions; reactors and separators. • Hazard analysis studies to review the process chemistry and engineering practices, including thermodynamics and With the High Density Polyethylene (HDPE) and Linear Low kinetics; Density Polyethylene (LLDPE) solution process, fire hazards • Examination of preventive maintenance and mechanical originate from high-pressure and high-temperature conditions in integrity of the process equipment and utilities; the polymerization reactor and desolventizer operating at a • Worker training; and temperature close to self-ignition temperature of the solvent, • Development of operating instructions and emergency together with high flow rates of hydrocarbon solvent. In HDPE response procedures. slurry process and in iPP bulk process, a spill from the reactor can result in an explosive cloud due to flash evaporation of Process safety recommendations applicable to specific isobutane and propylene. The prevention of spills and explosive manufacturing processes are presented below. clouds should be based on the application of internationally recognized engineering standards for equipment and piping Polyethylene Manufacturing design, maintenance, plant lay-out, and location / frequency of In polyethylene manufacturing, a specific process hazard is emergency shut-off valves. related to the possible release of large amounts of hot ethylene to the atmosphere and subsequent cloud explosion. Accidental PVC Manufacturing events are mainly related to leaks from gaskets or during Accidental venting to the atmosphere of VCM with a subsequent maintenance operations. For LDPE production units in formation of an explosive and toxic cloud can be caused by particular, accidental events can include opening of the safety opening of Pressure Safety Valves (PSVs) of a reactor due to disk of the reactor and explosion of the high pressure separator. runaway polymerization. Management actions include Specific safety management measures include the following: degassing and steam flushing of reactor before opening. • Ethylene vented due to opening of the reactor safety disks VCM is easily oxidized by air to polyperoxides during recovery at high pressure cannot be conveyed to the flare, but operations after polymerization. After recovery, VCM is held in should be vented to the atmosphere by a short stack, after a holding tank under pressure or refrigeration. A chemical dilution with steam and cooling with water scrubbing to inhibitor, such as a hindered phenol, is sometimes added to minimize risks of explosive clouds; prevent polyperoxide formation. Normally any polyperoxide APRIL 30, 2007 9 Environmental, Health, and Safety Guidelines PETROLEUM-BASED POLYMERS MANUFACTURING WORLD BANK GROUP formed is kept dissolved in VCM, where it reacts slowly and facilities should include consideration of distances to monomer safely to form PVC. However, if liquid VCM containing plants, in order to minimize storage times and to reduce polyperoxides is evaporated, polyperoxides may precipitate and potential hazards from monomer transport.13 decompose exothermically with the risk of explosion and consequent toxic cloud.11 Styrene Styrene polymerizes readily and should be stored at cool Batch Polymerization Process temperatures, with adequate levels of 4-tert-butylcatechol (TBC) Batch polymerization can generate a hazard of runaway used as an inhibitor, in tanks designed and built according to polymerization and reactor explosion in the event of improper international standards. dosing of reactants or failure in the stirring or heat exchange systems. Recommended process safety management practices Acrylic Acid and Esters 14,15 include limiting the practice of batch polymerization and the Acrylic acid is a liquid freezing at 13 °C, and is extremely application of process controls, including the provision of backup reactive by runaway polymerization if uninhibited. Accidents emergency power, cooling, inhibitor addition systems, and blow- originated in acrylic acid storages are relatively frequent. down tanks. It is sold inhibited with hydroquinone mono methyl ether, which Compounding, Finishing and Packaging Processes is active in the presence of air. It is easy flammable when overheated and it should be stored in stainless steel tanks. Compounding, finishing, and packaging operations present risks Overheating or freezing should be avoided because thawing of of fire in blenders and in extruders (if the polymer is overheated), and in equipment involving mixtures of polymer frozen acrylic acid is an operation involving runaway polymerization risks. Acrylic esters behave in a similar way, but powders and air, such as dryers, pneumatic conveyors, and they don’t present risks related to freezing. grinding equipment. Use of internationally recognized electric installation standards, including grounding of all equipment, and Phenol installation of specific fire fighting systems are recommended. Phenol melts at 40.7°C and it is usually received, stored and Fires and Explosions handled in molten state. Tanks should be fitted with a vapor recovery system and fitted with heating coils; nitrogen blanket is Vinyl Chloride Monomer (VCM) also recommended. Lines and fittings should be steam-traced VCM is classified as a toxic and carcinogen (IARC group 1)12. It and should be purged with nitrogen before and after product is gas under normal conditions (boiling point = -13.9°C), and is transfer. potentially explosive when in contact with air. VCM is stored as a liquid in pressurized or refrigerated tanks. Transportation of VCM, including pipeline transportation, should be conducted in a 13 The cost of transportation may be a significant contributing factor to the co- manner consistent with good international practice for transport location of new facilities in proximity to sources of VCM. 14 Acrylic acid - A summary of safety and handling, 3rd Edition, 2002; of hazardous materials. Evaluations for the location of new PVC Intercompany Committee for the Safety and Handling of Acrylic Monomers, ICSHAM 11EIPPCB BREF (2006) 15 Acrylate esters – A summary of safety and handling, 3 rd Edition, 2002 ; 12IARC Monographs on the Evaluation of Carcinogenic Risks to Humans, Intercompany Committee for the Safety and Handling of Acrylic Monomers, Volume 19 http://monographs.iarc.fr/ENG/Monographs/vol19/volume19.pdf ICSHAM APRIL 30, 2007 10 Environmental, Health, and Safety Guidelines PETROLEUM-BASED POLYMERS MANUFACTURING WORLD BANK GROUP Formaldehyde should be sloped to facilitate drainage to an emergency Formaldehyde is used as an aqueous solution at concentrations burning pit. of 37 – 50 percent, usually stabilized with low amounts of methanol (<1 percent). Formaldehyde is a confirmed Peroxides carcinogenic for humans (IARC Group 1)16 Formaldehyde Organic and inorganic peroxides, as well as diazo compounds, releases flammable vapors to air, so it should be kept under an are widely used as radical polymerization initiators. Inorganic inert gas blanket during storage. peroxides, like hydrogen peroxide and peroxydisulfates, are capable of violent reaction with organic substrates. Inorganic Metal alkyls (Al, Li, Zn, Na, K, etc.) peroxides are classified as oxidizers. Oxidizer hazards include The most widely used metal alkyls are aluminum and increase in the burning rate of combustible materials; magnesium alkyls in Z-N polymerization of olefins, and lithium spontaneous ignition of combustible materials; rapid and self- alkyls in anionic polymerization of styrene and dienes. sustained decomposition, which can result in explosion; Recommended management practices include: generation of hazardous gases; and explosion hazards if mixed • Preparation of a specific fire prevention and control plan to with incompatible compounds or exposure to fires. address the fire and other hazards associated with metal Recommended management practices include: alkyls;17 • Peroxide formulations should be transported and handled • Respecting safety distances within and outside of the according to manufacturer recommendations and facility;18 applicable international standards 20,21,22. • Shipping in tank cars, tank trailers, portable tanks, or ISO • Storage should be segregated facilities designed and built tanks according to internationally recognized standards;19 according to internationally accepted standards (e.g. NFPA • Transfer should be made to bunkerized storage facilities Codes23 24). Organic peroxides should be stored in through specially designed valves, fittings, and pumps; dedicated refrigerated or air conditioned explosion proof • Storage tanks should be kept under a nitrogen blanket and buildings;25 connected to the atmosphere by one or more oil hydraulic • Preparation of a specific fire prevention and control plan to seals. The product levels and flows should be monitored address the peculiarities of strong inorganic oxidizers.26 with high reliability instrumentation and alarms; • Metal alkyl storage facilities should be equipped with containment walls, and the area within the containment 20 UN Recommendations on the Transport of Dangerous Goods. Model Regulations. Thirteenth revised edition (2003) 21 Safety and handling of organic peroxides: A Guide Prepared by the Organic 16 IARC Monographs on the Evaluation of Carcinogenic Risks to Humans, peroxide producers safety division of the Society of the plastics industry, Inc. Volume 88 http://monographs.iarc.fr/ENG/Monographs/vol88/volume88.pdf Publication # AS-109 17 Fog spray may be used to deactivate pyrophoric alkyls. Larger amounts of 22 NFPA 432, Code for the Storage of Organic Peroxide Formulations, 2002 water or foam should not normally be used as fire extinguishing agents due to Edition their violent reactivity with aluminum alkyls. Water may be used to cool adjacent 23 NFPA 430, Code for the Storage of Liquid and Solid Oxidizers, 2004 Edition objects directly or as a water screen to shield any objects from heat radiation. 24 NFPA 432, Code for the Storage of Organic Peroxide Formulations, 2002 Other agents such as CO 2 or other chemical powders are needed in large Edition amounts to control the fire and prevent re-ignition. 25 Class 3 peroxides may require less stringent storage standards. 18 E.J Major, H.G. Wissink, J.J. de Groot, (Akzo Nobel), Aluminum Alkyl Fires 26 For example, the most appropriate fire extinguishing agent for organic 19 UN Recommendations on the Transport of Dangerous Goods. Model peroxides is liquid nitrogen applied with remotely operable fire fighting Regulations. Thirteenth revised edition (2003) equipment. APRIL 30, 2007 11 Environmental, Health, and Safety Guidelines PETROLEUM-BASED POLYMERS MANUFACTURING WORLD BANK GROUP Polymers potential for accidents may vary among facilities depending on Fires in polymer storage warehouses may be difficult to control design, on-site equipment, and infrastructure. Confined spaces due to the very high combustion heat of most polymers. in polymer manufacturing facilities may include reactors which Polymers combustion in fires also produces toxic clouds. must be accessed during maintenance activities. Facilities Recommended management practices include: should develop and implement confined space entry procedures as described in the General EHS Guidelines. • Storage buildings should be designed in accordance with internationally accepted standards including, for example, 1.3 Community Health and Safety appropriate ventilation, air temperature control, and Community health and safety impacts during the construction protection from direct sunlight; and decommissioning of polymer manufacturing facilities are • Effective fire prevention and control systems should be common to those of most other industrial facilities and are adopted, including for example, smoke detectors, IR hot discussed in the General EHS Guidelines. The most significant spot detectors, and distributed water sprinklers designed community health and safety hazards associated with polymer for the very high thermal load of a polymer fire; manufacturing facilities occur during the operation phase and • Because most polymers are subjected to slow oxidative include the threat from major accidents related to potential fires aging by heat or light, they should be kept in closed and explosions or accidental releases of finished products within packaging; the facility or during transportation outside the processing • “First In First Out” (FIFO) management procedure for the facility. Guidance for the management of these issues is products together with frequent inspections and good presented above under the environmental and occupational housekeeping. Aged materials should be traced, evaluated health and safety sections of this document. Major hazards for safety, and separated for disposal. should be managed according to international regulations and best practices (e.g., OECD Recommendations,27 EU Seveso II Chemicals Directive,28 and USA EPA Risk Management Program Rule).29 Potential inhalation and dermal contact exposures to chemicals during routine plant operations should be managed based on Additional guidance on the management of hazardous materials the results of a job safety analysis and industrial hygiene survey is provided in relevant sections of the General EHS Guidelines and according to the occupational health and safety guidance including: Hazardous Materials Management (including Major provided in the General EHS Guidelines. Protection measures Hazards); Traffic Safety; Transport of Hazardous Materials; and include worker training, work permit systems, use of personal Emergency Preparedness and Response. Additional relevant protective equipment (PPE), and toxic gas detection systems guidance applicable to transport by sea and rail as well as with alarms. shore-based facilities can be found in the EHS Guidelines for Confined Spaces Confined space hazards, as in any other industry sector, can, in 27 OECD, Guiding Principles for Chemical Accident Prevention, Preparedness the worse case scenario, potentially lead to fatalities if not and Response , Second Edition, 2003 28 EU Council Directive 96/82/EC, Seveso II Directive, extended by the Directive properly managed. Confined space entry by workers and the 2003/105/EC. 29 EPA, 40 CFR Part 68, 1996 — Chemical accident prevention provisions APRIL 30, 2007 12 Environmental, Health, and Safety Guidelines PETROLEUM-BASED POLYMERS MANUFACTURING WORLD BANK GROUP Shipping; Railways; Ports and Harbors; and Crude Oil and operating hours. Deviation from these levels due to specific local Petroleum Products Terminals. project conditions should be justified in the environmental assessment. 2.0 Performance Indicators and Monitoring Table 1. Air Emissions Guidelines Pollutant Unit Guideline Value 2.1 Environment Particulate Matter (PM) mg/Nm 3 20 Emissions and Effluent Guidelines Nitrogen Oxides mg/Nm 3 300 Hydrogen Chloride mg/Nm 3 10 Tables 1 and 2 present emission and effluent guidelines for this Sulfur Oxides mg/Nm 3 500 sector. Guideline values for process emissions and effluents in g/t s-PVC 80 Vinyl Chloride (VCM) g/t e-PVC 500 this sector are indicative of good international industry practice as reflected in relevant standards of countries with recognized Acrylonitrile mg/Nm 3 5 (15 from dryers) Ammonia mg/Nm 3 15 regulatory frameworks. These guidelines are achievable under VOCs mg/Nm 3 20 normal operating conditions in appropriately designed and Heavy Metals (total) mg/Nm 3 1.5 operated facilities through the application of pollution prevention Hg mg/Nm 3 0.2 Formaldehyde mg/m 3 0.15 and control techniques discussed in the preceding sections of Dioxins / Furans ng TEQ/Nm 3 0.1 this document. Emissions guidelines are applicable to process emissions. Resource Use, Energy Consumption, Emission Combustion source emissions guidelines associated with and Waste Generation steam- and power-generation activities from sources with a Table 3 (below) provides examples of resource consumption capacity equal to or lower than 50 MWth are addressed in the indicators for energy and water as well as relevant indicators of General EHS Guidelines with larger power source emissions emissions and wastes. Industry benchmark values are provided addressed in the EHS Guidelines for Thermal Power . for comparative purposes only and individual projects should Guidance on ambient considerations based on the total load of target continual improvement in these areas. emissions is provided in the General EHS Guidelines . 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. 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 APRIL 30, 2007 13 Environmental, Health, and Safety Guidelines PETROLEUM-BASED POLYMERS MANUFACTURING WORLD BANK GROUP Environmental Monitoring Table 2. Effluents Guidelines Environmental monitoring programs for this sector should be Pollutant Unit Guideline Value implemented to address all activities that have been identified to pH S.U. 6-9 have potentially significant impacts on the environment, during Temperature Increase °C =3 normal operations and upset conditions. Environmental BOD5 mg/L 25 monitoring activities should be based on direct or indirect COD mg/L 150 indicators of emissions, effluents, and resource use applicable Total Nitrogen mg/L 10 to the particular project. Monitoring frequency should be Total Phosphorous mg/L 2 sufficient to provide representative data for the parameter being Sulfide mg/L 1 monitored. Monitoring should be conducted by trained Oil and Grease mg/L 10 individuals following monitoring and record-keeping procedures TSS mg/L 30 and using properly calibrated and maintained equipment. Monitoring data should be analyzed and reviewed at regular Cadmium mg/L 0.1 intervals and compared with the operating standards so that any Chromium (total) mg/L 0.5 necessary corrective actions can be taken. Additional guidance Chromium (hexavalent) mg/L 0.1 on applicable sampling and analytical methods for emissions Copper mg/L 0.5 and effluents is provided in the General EHS Guidelines . Zinc mg/L 2 Lead mg/L 0.5 Nickel mg/L 0.5 Mercury mg/L 0.01 Phenol mg/L 0.5 Benzene mg/L 0.05 Vinyl Chloride mg/L 0.05 Adsorbable Organic mg/L 0.3 Halogens Toxicity To be determined on a case specific basis APRIL 30, 2007 14 Environmental, Health, and Safety Guidelines PETROLEUM-BASED POLYMERS MANUFACTURING WORLD BANK GROUP Table 3. Resource, Energy Consumption, Emission and Waste Benchmarks Parameter Unit Industry Benchmark (EU, 1999, Average best 50%) Product LDPE20 HDPE14 LLDPE GPPS HIPS EPS Direct energy consumption12 kWh/t 720 570 580 3002 4102 5002 Primary energy consumption13 kWh/t 2,070 1,180 810 -- -- -- Water consumption3 m3/t 1.7 1.9 1.1 0.8 0.8 5.0 Dust emission g/t 17 56 11 2 2 30 VOC emission 10 g/t 700 – 1,100 650 180 – 5001 85 85 450 - 7004 COD emission g/t 19 17 39 30 -- -- Inert waste kg/t 0.5 0.5 1.1 2.0 3.0 6.0 Hazardous waste kg/t 1.8 3.1 0.8 0.5 0.5 3.0 Product S-PVC E-PVC PET 15, 19 PA 615,17 PA 6615,16 Direct energy consumption kWh/t 750–1,100 2,000-3,000 850 – 1,500 1,800 – 2,000 1,600 – 2,100 Primary energy consumption kWh/t 1,100-1,600 2,800-4,300 -- -- -- Water to waste m /t 3 4.0 9 -- 0.6 - 25 1-3 1.5 – 3.0 Dust emission g/t 406,9 2006,9 -- -- -- Monomer emission to air5, 9,10 g/t 18 - 43 245-813 -- 6 – 10 -- VOC emission 10 g/t -- -- 518 -- 10 - 30 Monomer emission to water7,9 g/t 3.5 10 -- -- -- COD emission g/t 4808,9 3408,9 2,000 – 16,000 4,300 – 5,70016 4,500 – 6,00016 Inert waste kg/t -- -- 0.8 – 18 3.0 – 3.5 3.0 – 3.5 Hazardous waste 17 kg/t 559 749 < 0.45 0.2 – 0.5 0.2 – 0.5 Product UPES Direct energy consumption kWh/t < 1,000 Primary energy consumption kWh/t -- Water to waste m3/t 1 –5 Dust emission g/t 5 – 30 Monomer emission to air g/t -- VOC emission 10 g/t 40 – 100 Monomer emission to water g/t -- COD emission g/t -- Inert waste kg/t -- Hazardous waste kg/t <7 Source : EU IPPC BREF (2006) Notes: 1) According to type of comonomer (C4 or C8); 2) European average; 3) Not including cooling water purge; 4) 60% is pentane; not including storage; 5) Average best 25%; 6) PVC dust; 7) After stripping, before WWT; 8) After final WWT; 9) Median value; 10) Inclusive of diffuse emissions; 11) Direct energy is the total energy consumption as delivered; 12) Primary energy is energy calculated back to fossil fuel. For the primary energy calculation the following efficiencies were used: electricity: 40 % and steam: 90 %; 13) Good practice industry values; 14) iPP values can be considered more or less equivalent; 15) Before WWT; 16) Continuous process; 17) Solid waste containing > 1,000 ppm VCM; 18) Using catalytic oxidation (only point souces); 19) TPA process plus continuous post-condensation; 20) Based on tubular reactor APRIL 30, 2007 15 Environmental, Health, and Safety Guidelines PETROLEUM-BASED POLYMERS MANUFACTURING 2.2 Occupational Health and Safety Occupational Health and Safety Monitoring Performance The working environment should be monitored for occupational hazards relevant to the specific project. Monitoring should be Occupational Health and Safety Guidelines designed and implemented by accredited professionals35 as Occupational health and safety performance should be part of an occupational health and safety monitoring program. evaluated against internationally published exposure guidelines, Facilities should also maintain a record of occupational of which examples include the Threshold Limit Value (TLV®) accidents and diseases and dangerous occurrences and occupational exposure guidelines and Biological Exposure accidents. Additional guidance on occupational health and Indices (BEIs®) published by American Conference of safety monitoring programs is provided in the General EHS Governmental Industrial Hygienists (ACGIH),30 the Pocket Guidelines. Guide to Chemical Hazards published by the United States National Institute for Occupational Health and Safety (NIOSH),31 Permissible Exposure Limits (PELs) published by the Occupational Safety and Health Administration of the United States (OSHA),32 Indicative Occupational Exposure Limit Values published by European Union member states,33 or other similar sources. Accident and Fatality Rates Projects should try to reduce the number of accidents among project workers (whether directly employed or subcontracted) to a rate of zero, especially accidents that could result in lost work time, different levels of disability, or even fatalities. Facility rates may be benchmarked against the performance of facilities in this sector in developed countries through consultation with published sources (e.g. US Bureau of Labor Statistics and UK Health and Safety Executive)34. 30 Available at: http://www.acgih.org/TLV/ and http://www.acgih.org/store/ 31 Available at: http://www.cdc.gov/niosh/npg/ 32 Available at: http://www.osha.gov/pls/oshaweb/owadisp.show_document?p_table=STANDAR DS&p_id=9992 33 Available at: http://europe.osha.eu.int/good_practice/risks/ds/oel/ 35Accredited professionals may include Certified Industrial Hygienists, 34 Available at: http://www.bls.gov/iif/ and Registered Occupational Hygienists, or Certified Safety Professionals or their http://www.hse.gov.uk/statistics/index.htm equivalent. APRIL 30, 2007 16 FINAL DOCUMENT Environmental, Health, and Safety Guidelines PETROLEUM-BASED POLYMERS MANUFACTURING 3.0 References and Additional Sources Directive 2000/76/EC of the European Parliament and of the Council of 4 Oslo and Paris Commission (OSPAR). 2006. Recommendation 2000/3 for December 2000 on the incineration of waste Emission and Discharge Limit Values for E-PVC, as amended by OSPAR Recommendation 2006/1. Oslo, Norway and Paris, France. European Commission. 2006. Integrated Pollution Prevention and Control (IPPC) Reference Document on Best Available Techniques for Polymers. Oslo and Paris Commission (OSPAR). 1999. Recommendation 99/1 on BAT for October 2006. Sevilla, Spain the Manufacture of Emulsion PVC (e-PVC). Oslo, Norway and Paris, France. European Council of Vinyl Manufacturers (ECVM). 1994. Industry Charter for the Oslo and Paris Commission (OSPAR). 1998. Decision 98/5 for Emission and Production of VCM and PVC (Suspension Process). Brussels, Belgium Discharge Limit Values for the Vinyl Chloride Sector, Applying to the Manufacture of Suspension PVC (S-PVC) from Vinyl Chloride Monomer (VCM). Oslo, Norway and Paris, France. European Council of Vinyl Manufacturers (ECVM). 1998. Industry Charter for the Production of Emulsion PVC. Brussels, Belgium UN Recommendations on the Transport of Dangerous Goods. Model Regulations. Thirteenth revised edition, 2003. EU Council Directive 96/82/EC, so-called Seveso II Directive, extended by the Directive 2003/105/EC US EPA. 2000. 40 CFR Part 63 National Emission Standards for Hazardous Air German Federal Government. 2002. First General Administrative Regulation Pollutants for Amino/ Phenolic Resins Production. Washington, DC Pertaining to the Federal Emission Control Act (Technical Instructions on Air Quality Control – TA Luft). Berlin, Germany. US EPA. 1996. 40 CFR Parts 9 and 63 National Emission Standards for Hazardous Air Pollutant Emissions: Group IV Polymers and Resins. German Federal Ministry for the Environment, Nature Conservation and Nuclear Washington, DC Safety. 2004. Promulgation of the New Version of the Ordinance on Requirements for the Discharge of Waste Water into Waters (Waste Water US EPA. 40 CFR Part 63 — National emission standards for hazardous air Ordinance - AbwV) of 17. June 2004. Berlin, Germany. pollutants, Subpart F—National Emission Standard for Vinyl Chloride. Washington, DC Intercompany Committee for the Safety and Handling of Acrylic Monomers, ICSHAM. 2002. Acrylate Esters – A Summary of Safety and Handling, 3rd US EPA 40 CFR Part 60 — Standards of performance for new stationary Edition, 2002 sources, Subpart DDD — Standards of Performance for Volatile Organic Compound (VOC) Emissions from the Polymer Manufacturing Industry. Intercompany Committee for the Safety and Handling of Acrylic Monomers, Washington, DC ICSHAM. 2002 Acrylic acid - A summary of safety and handling, 3rd Edition, 2002 IARC Monographs on the Evaluation of Carcinogenic Risks to Humans Kirk-Othmer, R.E. 2006. Encyclopedia of Chemical Technology. 5th Edition. John Wiley and Sons Ltd., New York, NY. Organic Peroxide Producers Safety Division of the Society of the Plastics Industry. 1999. Safety and Handling of Organic Peroxides. Publication # AS- 109. Washington, DC National Fire Protection Association (NFPA). Standard 430, Code for the Storage of Liquid and Solid Oxidizers. 2004 Edition. Quincy, MA. NFPA. Standard 432, Code for the Storage of Organic Peroxide Formulations. 2002 Edition. Quincy, MA. NFPA Standard 654: Standard for the Prevention of Fire and Dust Explosions from the Manufacturing, Processing, and Handling of Combustible Particulate Solids OECD, Guiding Principles for Chemical Accident Prevention, Preparedness and Response, Second Edition, 2003 APRIL 30, 2007 17 FINAL DOCUMENT Environmental, Health, and Safety Guidelines PETROLEUM-BASED POLYMERS MANUFACTURING Annex A: General Description of Industry Activities Polymers Polymerization Processes Polymers are generally classified according to their physical Polymerization processes vary according to the properties of properties at service temperature including: monomers and polymers and their polymerization mechanisms. Polymerization reactors are either continuous or discontinuous • Resins: rigid, with high Young modulus36 and low (batch). In general, batch polymerization is chosen when the elongation to failure37; production capacity is small and/or the product range is broad, • Rubbers (or ‘elastomers’), with low Young modulus and leading to frequent campaign changes. Continuous high elongation to failure. polymerization is chosen for large scale production of a small number of polymer grades. They are also classified according to the types of manufacturing technologies used, including: Batch reactors are usually STR (Stirred Tank Reactor) type, equipped for heat exchange (internal coils, jacket, and reflux • Thermoplastics or thermoplasts: Soften and melt condensers) according to process needs; stirring is optimized reversibly when heated (harden when cooled). They are according to process needs. Continuous reactors are designed fabricated by molding or extrusion, or by smearing or on the basis of the process requirement and they can be of very dipping, diluted in solutions or in emulsions, as in the cases different types. Depending on the polymerization media, of coatings and adhesives; they can be easily recycled, processes can be classified as follows: though with a general degradation of their properties; • Thermosets: After curing, they harden permanently and • Solution polymerization: applied to monomers and decompose when heated to high temperatures. They polymers that are soluble in organic solvents or water; cannot be recycled after use. Thermosets are harder, more used for manufacturing HDPE, LLDPE, several acrylic dimensionally stable, and more brittle than thermoplastics. polymers for coating and adhesive markets, step-growth polymerizations, etc. Polymer Manufacturing Phases • Suspension polymerization: applied to insoluble Monomer and Solvent Purification monomers, polymers, and initiators or catalysts; used for Polymerization reactions need high purity raw materials and manufacturing PVC and EPS. The monomer is suspended chemicals because impurities can affect the catalyst or in the solvent in small drops (facilitated by stirring and negatively influence the product properties including changes in addition of a colloid), and the initiator, or catalyst, is the structure and reduction of the chain length. dissolved in the monomer. • Emulsion polymerization: the monomers, insoluble or sparingly soluble in water, are emulsified by soaps and other surfactants in droplets and are partly dissolved in 36 Measure of the stiffness of a given material. Defined as the ratio, for small strains, of the rate of change of stress with strain micelles by the excess soap. A water-soluble initiator 37 Measure of the ductility of a materials, it is the amount of strain it can experience before failure in tensile testing. starts the polymerization in the micelles, which grow as APRIL 30, 2007 18 FINAL DOCUMENT Environmental, Health, and Safety Guidelines PETROLEUM-BASED POLYMERS MANUFACTURING WORLD BANK GROUP polymer particles. Monomers and other reactants, as well and polymerization medium. These operations are often as new radicals, are fed to polymer particles by diffusion integrated with finishing operations. Flash evaporation, steam through the water. The final product from the reactor is a stripping, and wet nitrogen stripping are the most commonly stable dispersion of polymer in water (latex). Inverse used unit operations for recovery of unreacted monomers and emulsion (water-in-oil) polymerization is used for water- solvents. soluble monomers. Typical products obtained via emulsion polymerization are ABS, emulsion PVC, polyvinyl acetate, Finishing and acrylic latexes; Finishing of the polymers may include addition of additives, • Bulk (or mass) polymerization: monomer is directly drying, extrusion and pelletization, and packaging. Typical polymerized, after addition of initiator or catalyst or by product additives include antioxidants, UV absorbers, extension effect of heat or light. Typical products obtained by bulk oils, lubricants, and various kinds of stabilizers and pigments. polymerization are LDPE, GPPS and HIPS, iPP, PMMA Polymers are usually produced for sale as a powder (e.g. PVC), sheets, nylons, and PET; in granules (e.g. HDPE, EPS), in pellets (e.g. polyolefins, • Slurry polymerization: the polymer is insoluble in the polystyrene, PET, polyamides, PMMA), in sheets (e.g. PMMA), reaction medium, generally due to its crystalline properties. or in liquid emulsions or solutions. The polymer precipitates from the solution of monomer in solvent or from monomer itself and is maintained in Specific Processes and Products suspension (“slurry”) by stirring or from flow turbulence. Thermoplastics Polymer recovery is obtained by decantation (settler or Polyethylene decanting centrifuge). Active monomer solution can be Three main types of polyethylene are produced: LDPE, HDPE recirculated directly to the reactor. Batch and continuous and LLDPE. polymerizations are both feasible. Typical products obtained by slurry polymerization are polyolefins (HDPE, Low Density Polyethylene (LDPE) is produced in high pressure iPP); continuous process: ethylene is compressed up to 3,000 bar • Gas phase polymerization: Gas phase polymerization is (tubular reactor) or 2,000 bar (vessel reactor), and fed to the operated in a fluidized-bed reactor, where the catalyst is reactor, where oxygen or organic peroxide are injected to initiate added in fine dust form and polymerization is performed in the radical polymerization at 140 – 180 °C. Temperature of the the growing polymer particles, fluidized from the upward reaction is high, peaking to more than 300 °C. The ethylene – flow of monomer. Stirred reactors are also used to this polymer blend is continuously discharged to a high pressure purpose. Typical products obtained by gas-phase (250 bar) separator, where polymer precipitates and most of the polymerization are polyolefins (HDPE and iPP). unreacted ethylene is recovered, recompressed, and recycled to the reactor. Polymer is then fed to a low pressure separator, Polymer Recovery where degassing is completed. The molten polyethylene is then After polymerization, catalysts or initiators have to be destroyed finished by extrusion and pelletizing. and polymers have to be separated from residual monomers APRIL 30, 2007 19 Environmental, Health, and Safety Guidelines PETROLEUM-BASED POLYMERS MANUFACTURING WORLD BANK GROUP High Density Polyethylene (HDPE) and Linear Low Density • Gas phase process at 70 – 90 °C, 20 – 40 bar. Fluidized Polyethylene (LLDPE, linear copolymers with 1-butene, 1- bed reactors are used, as well as stirred vessel reactors, hexene or 1-octene) are produced by Ziegler-Natta or, recently both vertical and horizontal. by metallocene catalysis, with mostly the same processes and • Slurry process in liquid monomer at 60 – 80 °C, 20 – 50 in many instances in the same plants. Processes employed bar, also known as “bulk” or “liquid” phase process. A include: tubular loop reactor is used. • Gas phase polymerization: Large (> 500 m3) fluidized bed One or more reactors in series are used to produce a wide reactors are used, operating at relatively high pressure (20 range of polymers, including toughened isotactic Polypropylene – 30 bar), with high ethylene recycle through a gas cooler, (iPP) 38, containing copolymers with ethylene. The two types of to remove heat of polymerization. One or two reactors in reactors can be combined for better process optimization (e.g. series may be used. Spheripol® process). • Slurry process: HDPE can be produced in slurry Polyvinyl Chloride (PVC) continuous reactors (one or more reactors in series, in some cases (BORSTAR) coupled with gas phase Polyvinyl chloride (PVC) is produced by the polymerization of reactors), using as diluent isobutane in tubular loop vinyl chloride monomer (VCM). There are three different processes used in the manufacture of PVC: reactors and hexane or heptane in CSTR reactors. • Solution process: In the solution reactor, the polymer is • Suspension process; dissolved in a solvent/comonomer system. Typically, the • Emulsion process; and polymer content in a solution reactor is controlled at • Mass (bulk) process. between 10 and 30 wt-%. The reactor pressure is controlled between 30 and 200 bar, while the reactor Suspension PVC (S-PVC) is produced batchwise in a STR. The temperature is typically maintained between 150 and 250 monomer is dispersed in demineralized water by the °C. A hydrocarbon in the range of C6 to C9 is typically combination of mechanical stirring, colloids and surfactants. used as the solvent The polymerization takes place inside the VCM droplets under • High pressure process: LLDPE, VLDPE and ULDPE based the influence of VCM soluble initiators. The PVC suspension is on butene-1 copolymerization can be industrially produced then degassed to remove the bulk of unconverted VCM, and fed with Z-N catalysts by high pressure process, both tubular to a steam stripping tower, where traces of unconverted VCM and vessel." are removed. The product is subsequently sent to a Polypropylene centrifuge/rinsing system for the removal of impurities and for Two different kinds of processes are applied in the production of dewatering, and eventually to a drier. The dry polymer can then polypropylene: 38Isotactic polymers refer to those polymers formed by branched monomers that have the characteristic of having all the branch groups on the same side of the polymeric chain. APRIL 30, 2007 20 Environmental, Health, and Safety Guidelines PETROLEUM-BASED POLYMERS MANUFACTURING WORLD BANK GROUP be sieved and grinded as needed. The final step is packaging vacuum. This operation is called devolatilization. Water or storing in silos for bulk shipping. injection (steam stripping) can be added to improve monomer removal. Unreacted styrene and ethyl benzene are condensed In emulsion processes, PVC latex is produced. E-PVC is and recycled to the feed line. The molten polymer is then manufactured by three polymerization processes: batch pelletized (dry or under water).and dried for storing and emulsion, continuous emulsion and microsuspension. The packaging. VCM is dispersed using an emulsifier, usually a sodium alkyl or aryl sulphonate or alkyl sulphate. The polymerization takes Expandable polystyrene beads are produced by suspension place at the VCM water interface using initiators, such as an polymerization of styrene initiated by organic peroxides with the alkali metal peroxydisulphate. Residual VCM is removed by addition of pentane as blowing agent. The beads are separated stripping the latex. Latex is usually dried in a spray dryer and the by centrifugation, washed, and then dried for packaging. derived exhausts are a critical point for VCM emissions to the atmosphere. Acrylates Acrylic polymers are a wide class of polymers produced by Polystyrene radical polymerization of acrylic monomers (acrylic acid and its Three different types of polystyrene are produced: a transparent derivatives) and their copolymerization with other vinyl and brittle polymer called General Purpose Polystyrene (GPPS), monomers (e.g. vinyl acetate or styrene). The main acrylic a white, non-shiny but relatively tough, rubber modified monomers are acrylic acid itself, acrylamide, and a large range polystyrene called High Impact Polystyrene (HIPS), and the of acrylic esters, from methyl acrylate to fatty alcohol esters. Expandable Polystyrene (EPS). Water-soluble monomers, as acrylic acid and acrylamide, are usually polymerized in water solution or in inverse emulsion GPPS and HIPS are produced by continuous bulk polymerization. Acrylic esters polymers and copolymers are polymerization where the monomer is polymerized by radical produced in emulsion or in solution, according with their final polymerization, initiated by heat, with or without an organic use. peroxide. The main difference is that in HIPS manufacturing, medium- or high- cis-polybutadiene dissolved in styrene is Emulsion polymerization is the most diffused technology. added to improve polymer toughness. Solvents used in solution polymerization are alcohols, esters, chlorinated hydrocarbons, aromatics, according to the solubility The process may include the addition of solvent, initiator properties of the polymer. Initiators are organic or inorganic (optional), and chain transfer agents into the reactors under peroxides. Polymerization is usually performed in batches, in well-defined conditions. Styrene itself acts as the solvent of the stirred tank reactors, equipped with steam/water heat exchange reaction, although up to 10 % ethyl benzene may be added to systems. ensure better reaction control. Polyethylene Terephthalate (PET) To remove unconverted monomers and solvents, the crude PET is produced by polycondensation of terephthalic acid or its product is heated to about 220 - 260 °C and led through a high dimethyl ester (dimethyl terephthalate, DMT) with ethylene APRIL 30, 2007 21 Environmental, Health, and Safety Guidelines PETROLEUM-BASED POLYMERS MANUFACTURING WORLD BANK GROUP glycol (EG). The reaction is conducted in two steps, the first Thermosets step leading to a prepolymer of relatively low molecular weight Thermosetting polymers fabrication processes include chemical (raw polymer), the second leading to the final, high molecular crosslinking (networking) of their molecular structure, leading to weight polymer. The DMT process has largely been a material that does not melt, but decomposes on heating. The superseded by terephthalic acid (TPA) as the preferred reactive solid or liquid intermediate is transformed into the final industrial route to polyester production. product at the customer site by curing with hardeners or catalysts. Solid state polymerization can be operated in continuous, with various reactor designs, and hot nitrogen flow for heat exchange Phenolics and volatile reaction product removal, or in batch in a solids Phenolic resins are a family of polymers and oligomers, based mixer/drier operating under vacuum. on the reaction products of phenols with formaldehyde. Other raw materials include amines (hexamethylenetetramine Polyamides (Aliphatic) [HEXA]). Phenolic resins can be classified in: Polyamides have a macromolecular structure with the amide group (-NH-CO-) as a recurring functional unit that gives the • Novolaks (solid polymers by acid catalysts); specific chemical properties to the final products. Linear • High ortho novolaks (fast cure polymers by neutral polyamides, widely known as ‘nylons’, from the original DuPont catalysts); trademark name, are the most common category of the family. • Resoles (high formaldehyde-to-phenol molar ratio, liquids The family of polyamides is wide, with the number of carbon or solids, by alkaline catalysis). atoms in the monomers ranging from 4 to 12. Phenolic resins are produced in batch processes in STR For example, the monomer of polyamide 6 is e-caprolactam, reactors. polymerizing by step-growth polymerization. The main raw material for the production of polyamide 66 is an aqueous Unsaturated Polyesters solution of the organic salt (called AH salt, 66 salt or nylon salt) Unsaturated polyester (UPE) is the generic name for a variety of obtained by the reaction of 1,6-hexamethylene diamine and 1,6- thermoset products, mainly prepared by polycondensation of an hexane dicarboxylic acid (adipic acid). anhydride or a diacid (e.g., maleic anhydride, fumaric acid, phthalic anhydride, orthophthalic acid, isophthalic acid and Polyamides can be produced both by batch or continuous terephthalic acid) with a diol, (e.g., ethylene glycol, diethylene polymerization. After polymerization, the polymer melt he glycol, propylene glycol, butanediol, hexanediol, dipropylene polymer melt is extruded and cut, yielding chips. An extraction glycol, neopentyl glycol and dicyclopentadiene). These phase with hot water allows removes residual oligomers and condensation products are dissolved in a reactive monomer, monomers, and is followed by a drying phase. An extract which is usually styrene, but methyl methacrylate, t-butyl acetate waste processing phase is then needed to reuse the oligomers or diallyl phthalate are also used. When this mixture is cured by and monomers. the customer, a three-dimensional network is formed. Several APRIL 30, 2007 22 Environmental, Health, and Safety Guidelines PETROLEUM-BASED POLYMERS MANUFACTURING WORLD BANK GROUP hardeners, accelerators, inhibitors, additives and fillers are used The main polyurethane producing reaction is between a in the manufacturing process. diisocyanate (either aromatic or aliphatic) and a polyol (e.g., polyethylene glycol or polyester polyol), in the presence of The core of a resin plant usually consists of a number of batch catalysts, pigments, fillers, and materials for controlling the cell reactors, served by storage and dosing of raw materials and structure, and foaming agents and surfactants in the case of blending tanks for finishing of products, and equipped with heat foams. exchange systems and distillation columns, nitrogen, vacuum. Alkyds Alkyd coatings are a class of polyester coatings derived from the reaction of an alcohol and an acid or acid anhydride and are the dominant resin or "binder" in most "oil-based" coatings. Alkyd coatings are typically manufactured from acid anhydrides (e.g., phthalic anhydride or maleic anhydride) and polyols (e.g., glycerin or pentaerythritol). They are modified with unsaturated fatty acids (from plant and vegetable oils) to give them air drying properties. The drying speed of the coatings depends on the amount and type of drying oil employed and use of organic metal salts or "driers" which catalyze cross-linking. Based on their content of drying oil, alkyd resins are classified in “long oil”, “medium oil” and “short oil” Alkyd coatings are produced through two processes: fatty acid process and alcoholysis or glyceride process. In both cases the resulting product is a polyester resin to which drying oil groups are attached. At the conclusion of both processes the resin is purified and diluted in solvent. Polyurethanes The petrochemical industry produces the main polyurethane (PU) raw materials; polymerization is integrated in the process of fabrication of the final articles. Blending and compounding companies, named “system houses”, prepare and sell tailor- made systems to the final users. APRIL 30, 2007 23