Control of Pollution in the Iron and Steel Industry

CONTROL OF POLLUTION IN THE IRON AND STEEL INDUSTRY D. L. Doushanov Department of Fuel, Institute of Organic Chemistry, Bulgarian Academy of Sciences, Bulgaria Keywords: Environmental pollution, Sintering, Cokemaking, Ironmaking, Direct reduction, Steelmaking, Ferroalloy industry, Rolling, Skarfing, Pickling, Iron foundries, Steel foundries, Alternative technologies. Contents Introduction. 1. Sinter production: Control of pollution. 2. Coke production: Control of pollution. 3. Iron production: Control of pollution. 4. Steel production.Control of pollution. 5. Ferroalloy Production: Control of pollution. 6. Rolling: Control of pollution. 7. Iron foundries: Control of Pollution 8. Steel Foundries: Control of Pollution 9. Concluding remarks. Related Chapters Glossary Bibliography Biographical Sketch Abstract The iron and steel industry causes significant effects on environmental media – air, water and soil. In the sinter plants the dominant emissions generated from material handling, windbox exhaust, disharge end, and cold screen are particulate emissions - mainly iron oxides, sulfur oxides, calcium oxides, hydrocarbons, carbonaceous compounds, and chlorides. Emission of particulate matter, carbon monoxide, sulfur dioxide, organic compounds and other pollutants originate from several operations in the coking plants. Emissions from the blast furnace are generated from the top, in the casting stages, by drilling and plugging the taphole. During the casting operation, iron oxides, magnesium oxide and carbonaceous compounds are generated. The most significant emissions from the basic oxygen process are emitted during the oxygen blow period: iron oxides, mainly heavy metals and fluorides. The operations which generate emissions during the electric steelmaking are: melting - iron oxide; refining - calcium oxide from the slag; charging - iron and metallic oxides from alloy in the scrap; dumping slag and tapping steel - iron oxides and oxydes from the fluxes. During the semifinished product preparation the pollution is produced from the pouring of the molten steel into ingot molds and when semifinished steel is scarfed. Open dust sources include vehicle traffic; raw material handling and wind erosion from storage pile and contribute to the atmospheric pollution. The polluting emissions in the iron and steel industry are controlled by a variety of evacuation systems, devices, and methods such as cyclone cleaners, dry or wet electrostatic precipitators, scrubbers, bag houses, hoods, funrace enclosures; chemical, catalytic and biological methods. Introduction

The main types of plants involved in iron and steel industry are sintering plants, blast furnaces and steel works, direct reduction plants, ferroalloy production, rolling, scarfing, pickling, iron and steel foundry, and other technologies, such as argon - oxygen decarburization, ladle metallurgy vacuum degassing. Coking plants are considered here as part of this sector, since coke is produced practically exclusively for the iron and steel industry. The iron and steel industry causes significant effects on environmental media: air - emissions of SO2, NO x, CO, H2S, PAH, lead, Ni, As, Cd, Cr, Cu, Zn, Se, Hg, PM, etc.; water - process water with organic matter, oil, metals, suspended solids, benzene, phenol, acids, sulfides, sulfates, ammonia, cyanides, thiocyanates, thiosulfates, fluorides (scrubber effluent); soil slag, sludge, sulfur compounds, heavy metals, oil and grease residues, salts. The environmental sustainability of the blast furnace with its upstream stages coking and sintering plants is of great significance if existing capacities are to be retained or new ones are to be built. The blast furnaces built over the past years thus have a similar standard of environmental protection, independent of the location. The blast furnace process will remain the basic member in the technological chain of steel production in a foreseeable future. The coke production remains an inseparable part of the steel production. The needs for coke in the future will depend to a great extent on the factors influencing the reduction of these needs or rather on the possibility for alternative technologies to replace the blast furnace process. In 1995, about 358 million tones of coke have been produced in the world by 250 coke plants. Steel will remain the basis for economic development in the world. It is used to produce everything from sewing needles and tools to automobiles, ships and planes. Steel consumption will tend to follow the development in gross national product in the world. In accordance with the IISI,s data the total world steel production in 1997 was 793 million tons. The Protocol agreed at the Conference in Kyoto (1997) set out commitments to limit greenhouse gas emissions for industrial countries for the period 2008-2012. For example, emissions of CO2 only from fossil fuel combustion increased from 14.3 Gt (1971) to 22.1 Gt (1995) in the world. This document is very important for engineers, scientists and operators to implement technology strategies and public policies that prevent, reduce, or eliminate adverse environmental consequences in the iron and steel industry. From the standpoint of the new millennium there must be realized a change from a technology for fulfilling primary requirements only, to the development of modern, sustainable iron and steel technology within human activity in coexistence with environment on a global scale. 1. Sinter Production: Control of pollution Sinter plants have to fulfill increasing environmental regulations. For this plant manufacturers and operators had to develop new technical solutions for the reduction of pollution. Presently relevant new equipment has been installed at several sinter plants. For various pollutants, especially for dioxins and furanes further efforts are currently undertaken. For the blast furnace the future availibility of high quality sinter is of great importance because very few lump ores comply with the quality requirements of the blast furnace. Alternative quality feeds are limited in supply. This applies for pellets. The sintering converts fine-sized raw material, iron ore, coke breeze, limestone, mill scale, and flue dust into an agglomerated product (sinter) at suitable size for charging into the blast furnace. The raw materials are sometimes mixed with water to provide a cohesive matrix and

then placed on a travelling grate called the sinter strand. A burner hood, at the beginning of the sinter strand ignites the coke in the mixture. The combustion provides sufficient heat, from 13000C to 1480oC, to cause surface melting and agglomeration of the mix. On the underside of the sinter strand there is a series of wind boxes that draw combusted air down through the material bed to a gas cleaning. The fused sinter is discharged at the end of the sinter strand, where it is crushed and screened. The remaining sinter product is cooled in open air or in a circular cooler with water sprays or mechanical fans. The cooled product is crushed and screened for a final time, then the fines are recycled, and the product is sent to the blast furnaces. Practically two and a half tons of raw materials are required to produce one ton of product sinter. The pollution from sinter plants is generated from handling of raw material, wind box exhaust, discharge, cooler and cold screen. The cleaning of the sintering process gases is one of the most difficult cleaning problems in the steel industry. The wind box exhaust is the primary source of particulate emissions, mainly iron oxides, sulfur oxides, carbonaceous compounds, aliphatic hydrocarbons and chlorides. At the discharge end, emissions are mainly iron and calcium oxides. A cyclone cleaner, a dry or wet ESP, a wet scrubber or a bag house absorbs the sinter strand wind box emissions. The cyclone collectors are installed ahead of the induced-draft fans to remove particles with diameters of 25  m or greater. The dry ESP opperates with removal efficiencies of up to 99 per cent of the wind box emissions emited during the production of acid sinters. With the use of oil - bearing mill sclales in the feed materials, there are increased amounts of condensed hydrocarbon particulate matter in the wind box gases. Dry ESP is not efficient for hydrocarbons. The wet scrubbers are efficient in treating wind box gases. The wet scrubbers may remove the particles with diameters of one  m or less and they are capable of capturing the condensable hydrocarbons and other fine wind box gas particulate matter. The treatment of the scrubber matter requires neutralization of the acidic components from the scrubber and adding the coagulants for the clarification of the discharge maters before the re-circulation to the scrubber (see Control of Particulate Matter in Gaseous Emissions ). 2. Coke production: Control of pollution Metallurgical coke is produced by destructive distillation without contact with air in coke ovens until all volatile components in the coal evaporate. All metallurgical coke is produced using different recovery by-product coke oven systems: Koppers-Becker (Figure 1), Otto, Willput, PVR-Russia, Carl Steel, Koppers - Becker "underfind" and non recovery by-product coke ovens systems:

Figure 1: By-product coke oven battery showing major emission points "Jewell - Thompson ", "Pennsylvania Coke Technologies Inc. (PACTI)" - USA; "TJ - 75", "JKH - 97" - China. Process technology for cokemaking in pursuit of the aim to render innovative contribution to a future oriented steel production is available now: Multi Chamber - Systems (MCS) as demonstrated in the Kaiserstuhl, Single - Chamber - System (SCS), Non - Recovery/Heat Recovery Coke Oven (NR/HR - CO), 2 - Product - Cokemaking - Plant (2 - PCP). Conventional by-product recovery coke ovens. Coke manufacturing includes preparing, charging, heating the coal, removing and cooling the coke product. In addition the coke-oven gas is processed through a by-product recovery device exhauster consisting primarily of coolers, naphthalene scrubbers, ammonia absorbers, final coolers, benzene scrubbers and desulfurization facilities. The conventional recovery byproduct coke oven has three main parts: coking chambers, heating chambers and regenerative chambers, which are lined with refractory bricks. The coking chambers have ports in the top for charging of the coal. Process heat comes from the combustion of gases between the coke chambers. The maximum temperature attained at the center of the coke mass is usually 1100o C to 1150o C. After coking is completed the coke in the chamber is ready to be removed. The doors on both sides of the chamber are opened and the coke is pushed out of the oven into a quench car. The quench car with the hot coke moves to a tower where the coke mass is cooled from 1100o C to 80o C. The car then discharges the coke onto a wharf to drain and continue cooling. Gates on the wharf are opened to allow the coke to fall onto a conveyor that carries it to crushing and screening. After sizing, coke is sent to the blast furnace or to storage. Non recovery and new coke ovens. Cokemaking techniques must be offered and made available as viable design concepts taking into account the demand for a "lean" and adaptable process technology in coke production. Many projects are pursued worldwide to reach this goal.

In the NR / HR-CO "Jewell-Thompson" concept, following complete destruction of coal volatile matter, flue gas is drown through a spray dryer and a bag house to remove SO2 and PM before venting to the atmosphere. The ovens operate under negative pressure that prevents the release of hazardous air pollutants through leaks in the doors and crowns. The by product can be incinerated but the heat derived is used to generate power (see Management of Combustible Waste). The U.S. federal regulators have recognized the smog-free nature of the system. The 1990 amendments to the Clean Air Act (USA) specifically identify this process as setting the standard for MACT. 

The high-performance/single chamber system (HP-SCS) has ben developed within the framework of the European Cokemaking Technology Center (ECTC). This new system represents a perfect dissolution of the conventional multiple coking chambers system into an independent heavyload-bearing, high efficiency single chamber system to meat the requirements of a modern, environmentally adaptable "modular technology".



Conventional coke oven gas treatment in conjunction with coal byproducts recovery involve greater necessity of environmental control while not offering any satisfactory basis to play an active role in shaping linkage and structure for future steel plant. Consequently, the development of a "2PCP", that is cracking the coke oven gas with oxygen to get "new coke oven gas" (COG-N) come to a "lean" coke oven of the future. In this instance it is necessary to present the Japanese project "Super coke oven for productivity and environmental enhancement toward the 21-st century" (SCOPE - 21). This process features two stages. The first stage consists of a rapid- heating fine coal agglomeration process followed by a carbonisation in a horisontal chamber up to 750o C - 850oC. The second step is a heat treatment up to 1000o C in a coke dry quenching (CDQ). The innovative process shall guarantee improved environmental control and energy saving.

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Particulate matter, VOCs, CO and other emissions originate from several by-product coking operations: coal preparation, coal preheating (if used), coal charging, oven leakage during the coking period, coke removal, hot coke quenching and underfire combustion stacks.

Gaseous emissions collected from the ovens during the coking process are subjected to various operations for separating ammonia, coke oven gas, tar, phenol, benzene, toluene, xylenes and pyridine. These unit operations are potential sources of VOCs emissions. Small emissions may occur when transferring coal between conveyors or from conveyors to bunkers. A few plants preheat the coal to about 2600 C before charging, using a flash drying column by combustion of coke oven gas. The air stream that conveys coal through the drying column passes through conventional wet scrubbers for particulate removal before discharging to the atmosphere. In the conventional wet charging the emissions are similar. Oven charging can produce significant emissions of particulate matter and VOCs from coal decomposition if not properly controlled. Charging techniques can draw most charging emissions into a battery collecting mains. Effective control requires that goosenecks and the collecting main passages be cleaned frequently to prevent obstructions. During the coking cycle, VOCs emissions from the thermal distillation process can occur through poorly sealed doors, charge lids, off-take caps, collecting main, and cracks that may

develop in oven brickwork. Door leaks may be controlled by diligent door cleaning and maintenance, rebuilding doors, and in some plants, by manual application of lute material. Charge lid and off-take leaks may be controlled by an effective patching program. Pushing coke into the quench car is another major source of particulate emissions. If the mass is not fully coked, VOCs and combustion products will be emitted. Most facilities control pushing emissions by using mobile scrubber cars with hoods shed enclosures evacuated to a gas cleaning installation, or traveling hoods with a fixed duct leading to a stationary gas cleaner. Coke quenching entrains particulate from the coke mass. The dissolved solids from the quenched water may become entrained in the steam plume rising from the tower. Coking plant waste water generated from high temperature coal carbonization, associated gas purification and chemical processing is very complex in composition. Concentrations of various pollutants are very high and highly toxic, very hard to treat. Sources of waste water are: excess ammonia liquor from coal carbonization and raw gas cooling, water from gas purification such as gas final cooling and crude benzene separation, water from coal tar, crude benzene refining and other processes. Waste water separated from raw gas and coal tar contains as much as ten thousands compounds. Many of these compounds dissolve. Of these dissolved compounds not only large amounts of inorganic matters are present such as ammonia, sulfide, cyanide, chloride, thiocyanide radicals and compounds of silicon, calcium, iron, boron, magnesium, potassium, sodium and germanium, but also organic matter in a still larger amount. Analysis of coking plant wastewater shows that nearly one thousand compounds are present in a concentration not higher than one  g l-1 . These include not only large amounts of acidic organic matters, such as phenol, cresol, naphthol and nitrogen containing basic organic matters like pyridine, aniline, quinoline, carbazole and acridine etc., but also large amounts of PAH, such as BaP. The typical analysis of a coke plant waste water stream (mg l-1) is following: COD - 25003500; phenols - 280-500; ammonia - 10-70; sulfide - 2-15; thiocyanide - 250-350; cyanide 10-20. To clean coke plant waste water dephenolization devices were built on large-scale coke plants. These extraction processes include, for example: "Phenosolvan"- operates on a low-boiling solvent (diisopropylether), "Podbielniak" and "Pott-Hilgenstok" - also operate on benzol caustic solution. In these processes the efficiency degree of phenol scrubbing moves from 93 per cent to 99 per cent. Apart from phenol other organic substances are scrubbed out in the dephenolization devices causing a reduction (per cent) of: COD - 70-75; BOD - 40-60; total organic carbon - 52-62. At present, conventional bio-chemical processes are widely used for coking plant waste water treatment (see Control of Pollution in the Chemical Industry and Control of Pollution in the Petroleum Industry). 3. Iron production: Control of pollution 3.1. Ironmaking Iron is produced in blast furnaces by the reduction of iron bearing materials with a hot gas. During the residence time in blast furnace, coke has to serve different functions: heat resources, producer and regenerator of reducing gas, supporting structure, carburizing agent and dust filter. Coke is partly gasified. Carbon and oxygen react to carbon monoxyde (1):

2C + O2  2CO + heat

(1)

Carbon monoxyde is used as reducing gas. The CO in the gas then reacts with iron oxyde in the stack, producing metallic iron and CO2 Fe2O3 + 3CO  2Fe + 3CO2

(2)

At temperatures above 900-1000o C direct reduction starts and CO react with carbon from coke (3): C + CO2  2CO

(3)

Again CO reduces the iron oxydes. All the phosphorus pentoxide, some of the silica and manganous oxide are reduced, also, while phosphorus, silicon, and manganese dissolve in the iron tougether with some carbon from the coke. Then iron oxides, fluxes and coke react with the blast air to form molten reduced iron, CO and slag. The large, refractory lined furnace is charged through its top with iron as ore, pellets, (or sinter); flux (limestone, dolomite) and coke. The molten iron and slag collect in the hearth at the base of the furnace. The production of one ton of iron requires: 1.4 tons of ore, 0.5 to 0.65 tons of coke, 0.25 tons of limestone (dolomite) and 1.8 to 2 tons of air. Byproducts consist of 0.2 to 0.4 tons of slag, and 2.5 to 3.5 tons of blast furnace gas containing up to 40 kg of dust. The molten iron and slag are removed, or cast, from the furnace periodically. The casting process begins with drilling a hole, called taphole, into the clay-filled iron notch at the base of the hearth. During casting, molten iron flows into runners that lead to transport ladles. Slag also flows into the clay-filled iron notch at the base of the hearth and also flows from the furnace to a slag pit. The utilization of water as a coolant for slag quenching, results in H2S pollution. A reduction in H2S emission can be achieved by increasing the air cooling before water is used. A reduction in H2S can also be realized by adding caustic or potassium permanganate to the quench water. It is possible to attain reduction of 80-85 per cent of H2S. A combination of a 2 -3 days cooling period better the quenching as well as an addition of KMnO4 to the quench water. The blast furnace by-product gas is collected from the top and contains CO and particulate. This gas has a heating value about 2800 to 3300 J l-1 and is used as a fuel within the steel plant. The diagram for the iron and steel industry is presented in Figure 2.

Figure 2: General flow diagram for the iron and steel industry The cleaning of pollution ingredients from the blast furnace creates complex problems for resolution. The blast furnace gases pass through a dry cyclone to remove about 60 per cent of the particulate and in the next step, the gases undergo cleaning operations. The primary cleaner is normally a wet scrubber, which removes about 90 per cent of the remaining particulate. The secondary cleaner is a Venturi or an ESP, either of which can remove up to 90 per cent of the particulate, which eludes the primary cleaner. These operations provide a clean fuel of less than 0.06 g m-3 grains. A portion of this gas is fired in the stoves of blast furnace to preheat the blast air. The casting operation is the primary source of blast furnace emissions: iron oxides, magnesium oxide and carbonaceous compounds are generated as particulate. Casting emissions are controlled by evacuation through retrofitted capture hoods to a gas cleaner, or by suppression gases like CH4 and N2 at the ladle spot, trough and runner. The principle of suppression is to eliminate oxygen from contact with liquid iron during casting. Emissions controlled by hoods and an evacuation system are usually vented to a bag house. Another source of emissions is the blast furnace top during charging from imperfect bell seals. A modern charging installation - bell-less Paul Wurth- minimizes this pollution. Sulfur in the molten iron is sometimes reduced before charging into the steel making furnace by adding reagents with the formation a floating slag, which can be skimmed off. Desulfurization may be performed in the hot metal transfer (torpedo) car at a location between the blast furnace and the BOF, or it may be done in the ladle inside the BOF. Powdered reagents CaC2, CaCO3 or salt-coated magnesium granules (containing 85 per cent Mg) are injected into the metal with high-pressure N2. Calcium carbide desulfurizes the hot metal, and CaCO3 provides the CO2 hich mixes the hot metal and the desulfurizing powder. The Mg-salt

goes through the boiling dissolution during the desulfurization. Most of the reagents are captured by the slag. The remaining salts are evacuated as a fume. The treatment can reduce the sulfur level down to less than 0.005 per cent. Coal injection, together with increasing amounts of oxygen and natural gas, continue to be adopted in blast furnace operations to reduce coke consumption and increase productivity. In Germany and Japan was completed the construction of an integrated waste plastics recycling system in which processed plastics are blown into the blast furnace. In Japan, for example, it is planned to recycle 30 000 tons of industrial waste plastics (excluding polyvinyl chloride) annually. A maximum addition of 200 kg of waste plastics ton-1 charge is anticipated. Benefits include reduced coke consumption, reduced emission of carbon dioxide compared with current incineration processes, and no generation of harmful by-product gas. 3.2. Direct reduction to iron The blast furnace is the dominant method of smelting iron from oxides. Steel producers using EAF based on scrap are moving upscale rolling products that require lower levels of residual elements available from direct reduiced iron (DRI). The amounts of DRI available of the number of molten iron facilities grow substantially. In 1999 direct reduction plants produced 17.8 million tons or 3 per cent of world steel production. The first industrial production of hot metal (molten iron) without the use of coke metallurgy was realized with DRI in the Corex plant at the 1980 for the production of solid sponge iron. The blast furnace and the Corex (based on coal) are the only ones smelting reduction processes for the production of liquid hot metal. The gas from Corex process is similar to coke oven gas and can be used as a fuel in boilers. The sulfur from the coal forms an agglomeration with the constituents of the slag. A part of the sulfur leaves the device as H2S. The clean-up system comprising a standard boiler is used to remove the SO2 and NOx (see Mechanical and Cyclonic Collectors). The Midrex (Midland Ross Corporation) and HYL - III processes with the charge of lump ore as well as the Fior, Circored and Finmet processes with the use of fine ores, are used in practice for the production of sponge iron based on the use of natural gas (NG) in vertical shaft type plants. In the Midrex process the reducing gas is obtained through the cracking of the NG in a reformer. The reducing gas is blown into the shaft. The top gas, rich on CO2, passed through the scrubber and cooled to about 40oC, is used for cracking as well as for heating the NG in the reformer. One third of the cleaned gas must be purged to remove CO2 and N2. The purged gas from reformer is cleaned by a scrubber or ESP. The sulfur removed from the reformer cycle may be recovered. The sponge iron is cooled in separate area or is extracted for hot briqueting. Usually Midrex plants operate with pellets (80 per cent), because too high percentage of lump ore can increase the dust in the crud gas. The HYL - III operates similar to the Midrex but in this case the reducing gas contains a large per cent of H2 which is produced through the reaction of NG with steam. In 1990 Midrex and HYL accounted for 90 per cent of DRI in the world. The SL/RN and DRC rotary kiln processes as well as the Inmetco rotary hearth process are in operation for DRI, based on coal. The total dust collected from the raw material and the product-handling amount to from 250 kg t-1 to 300 kg t-1 of iron produced. The waste gas contains hydrocarbons, CO and H2. The air in the kiln influence whether the sulfur is present as oxides or H2S. About one third of the sulfur in the feed reverts to the SO2. The destruction of PAH is favorized by reducing the temperature from 1200oC to 500oC at the exit. The exhaust gas is combusted in an afterburner. An afterburner would require a scrubber for PM. The alternative use of boiler needs the use of ESP for PM removal. The medium heat content

gases do not produce high amounts of NOx. The SO2 and the NOx removing methods are the same as with the conventional boilers (see Thermal and Catalytic Combustion). The Finmet process is a further development of the Fior process. In both cases the reducing gas is produced through the cracking of the NG with steam. The sponge iron production occurs in a reduction of fine ores in the fluidized beds. The extracted fine-grained sponge iron is directly briquetted. The hot metal bath process, Hismelt, differs from the other DRI processes with the influence of the coal-reactant on the volatile and nonvolatile organic emissions from the furnace. Most of the sulfur from the coal and the metallic feed would stay with slag and metal. This process operates at high temperature and in these conditions the N2 from the infiltrated air sometimes produce high NO2 concentration. The PAH would be destroyed if the temperature at the mouth of the combustion hood is over 850oC. The SO2 retained by the oxides in the prereduction step. The PM from this device is similar to those from a BOF. The comparison of the blast furnace route, including the sinter and coking plants, or hot metal production and DRI shown that the blast furnace route and particularly for integrated steel production represent the most cost effective route. The production costs of Corex can approach the more advantageous hot metal costs of the modern blast furnaces. The production of sponge iron is more favorable from the DRI based on coal rather than NG. Direct reduction iron plants based on NG can more efficiently produce iron in the countries with cheap energy sources. 4. Steel production: Control of pollution 4.1. Basic oxygen process In the basic oxygen process (BOP), molten iron and iron scrap are refined by injecting oxygen in a furnace. The charge is 70 per cent molten iron and 30 per cent scrap. The oxygen reacts with carbon and other impurities to remove them from the metal. The CO produced by the reactions in the BOF can be controlled by combustion at the mouth of the furnace and then oriented to gas cleaning, as with open hoods, or the combustion can be suppressed, as with closed hoods. The BOP is conducted in large refractory lined pear shaped furnace with a capacity up to 400 tons. There are different modifications of the process. The conventional BOP has oxygen blown into the top of the furnace through a water cooled injection. In the Quelle Basic Oxygen Process (Q-BOP), oxygen is lanced through tuyeres located in the bottom of the furnace. The third type is the combined blown ( K-OBM) furnace, where 30 per cent of oxygen is blown through the bottom. Nitrogen, Ar, NG and powdered lime can also be injected through the bottom tuyeres. A typical BOP cycle consists of the scrap charge, hot metal charge, oxygen blow, alloy addition, tapping and slagging. The full cycle ranges from 20 to 50 minutes. Significant pollution from the BOP occurs during the oxygen blowing period. The predominantly emitted compounds are iron oxides, but also heavy metals and fluorides are present. Charging emissions depend on the particular quality and quantity of the scrap charged to the furnace and on the pour rate. The tapping emissions include iron oxides, sulfur oxides and other metallic oxides, depending of the grade of used scrap. Hot metal transfer emissions are mostly iron oxides. The BOF is equipped with a primary hood capture system located directly over the open mouth of the furnace to absorb the emissions during the period of oxygen blow. Two types of capture systems are used to collect exhaust gas as it leaves the furnace mouth: closed hood or open hood.

4.2. Electric Arc Furnace The electric arc furnaces (EAF) are used to produce carbon and alloy steels. The input material to an EAF is 100 per cent scrap. EAF are the prime means of recycling steel scrap into liquid steel. Cylindrical, refractory lined EAF is equipped with carbon electrodes lowered through the furnace roof. With electrodes retracted, the furnace roof can be rotated aside to permit the charge of scrap steel by overhead crane. Alloying agents and fluxing materials usually are added through the doors on the side of the furnace. Electric current between the electrodes generates heat through the scrap. After melting and refining periods, the slag and steel are poured from the furnace by tilting. The production of steel in an EAF is a batch process. Cycles range from about 1 to 5 hours to produce carbon steel and from 5 to 10 hours to produce alloy steel. Scrap steel is charged to begin a cycle. Alloying agents and slag are added for refining. Stages of each cycle are charging, melting, refining (oxygen blowing) and tapping. The operations, which generate emissions, and dust specially, during the process are melting, charging scrap, tapping steel and dumping slag. Iron oxide is the major constituent of the PM emitted during melting. The PM emitted during refining is calcium oxide from the slag. The charging scrap emissions usually contain iron and other metallic oxides from alloys in the scrap metals. The constituents of the slag emissions are iron oxides from the fluxes. During the tapping, iron oxide is the major PM emitted. The industry uses the following capture systems: direct shell evacuation, side draft hood, combination hood, canopy hood, and furnace enclosures. Direct shell evacuation consists of ductwork attached to a separate or fourth hole in the furnace roof, which draws emissions to a gas cleaner. This system works when the furnace is upright with the roof in place. Side draft hood collect furnace off gases from around the electrode holes and the doors after gases leave the furnace. The combination hood incorporates elements from the fourth hole and side draft systems. An air gap in the ducting introduces secondary air for combustion of CO in the exhaust gas. The canopy hood captures emissions during charging and tapping. In the different EAF the canopy hood is incorporated with one of the other preceding systems. The furnace enclosure surrounds the furnace and evacuates the emissions through hooding in the top of the enclosure. 4.2.1. Electric Arc Furnace Dust Treatment Electric arc furnace dust is a hazardous waste because it fails some test for lead, cadmium and chromium. Electric arc furnace treatment creates different opportunities: a hazardous waste can be rendered innocuous and its products safely enter again the environmental cycle and the great quantities of already mined and concentrated zinc, iron, chromium and nickel can be returned to the economics. For example, in the Italy mini mill dust recycling facilities has the capacity to process 10 000 tonnes of dust annually, removing 2000 tons of zink. In Japan, the Kawasaki Steel has a method to recover iron and zink from EAF dust that is similar to the process in the blast furnace. It utilizes a shaft furnace with two tiers of tueres and a zinc recovery at the top of the furnace. In the U.S. 700 000 tons year-1 of EAF dust are removed. This quantity contains 100 000 tons of zink and 200 000 tons of iron. The range of chemical composition for carbon steel EAF dust in the U.S. is following (per cent): zinc - 15-25, lead 2-5, cadmium - 0.1-0.2, chlorine - 1-5, and iron - 30-40. The methods of treating EAF dust are included: pyrometallurgical (kiln, flame reactor, bath smelting, and plasma and electric based) - Waels kiln, ZTT Ferrolime, MR Electrothermic, Ausmelt, MetWool, Enviroplas, etc.; hydromatallurgical (acidic or basic leaching alone or

combined with electrowinning) - EZINEX, Resada, Cashman; stabilization using cement and other additives; glassification; and hybrid hydrometallurgical/pyrometallurgical - MRT and IBDR - ZIP. The economics for treating dust depending on the process employed. The main factor ranges generally apply: tipping fees - $150-200 ton-1 dust; transportation costs - $15-50 ton-1 dust; operating costs - $100-200 ton-1 dust. Producing high value zinc metall selling for $1000 ton-1 and metallized iron as a scrap replacement selling for $100 to 120 ton-1 rather than leady zinc oxide ($300 ton-1), iron oxide ($40 to 50 ton-1), or slag ($5 to 15 ton-1) is a prospective economic direction. Argon – oxygen decarburization processis used for the production of speciaalty steel.The vessels oo this process are charged with high carbon andccchromium molen steel from EAF.The process is a converter type that is equipped with gaas injection of oxygen with argon or nytrogen and air in the bottom.This is necessary for the decarburizing the wwthout oxxxxxydizing the alloing components.The gas,blown through the bottom into the molten steel, generates the primary pollution.These emissions are captured in a local hood and oriented to the EAF fume system. The primary off-gas hood require attentive maintenance if it is not designed to withstand impringement by the flame of the vessel-mouth.The vessel offgas ( CO and the inert injection ) is burned and collect.The hood and ssubsequent ducting are water cooled.Canopy hood, similar to those of EAF canopy hood, is used to capture the emissions of processes charging and tapping. Ladle metallurgy vacuum degassing is used to adjust the composition and the temperature of a steel heat from aprimary melting furnace such as EAF or BOF. Ladle metallurgy facilities include a series of processes: injection or addition of fluxes, nonferrous metals and gases; raking or skimming of slag; degassing by vacuum; and electric arc reheating. These were introduced to producecleaner steel in response to more stringent standards.The combination of processesat a different plants depends on the product made, the requirements of the melting furnace and contnuous caster, the quality desired. The ladle metallurgy facilities includes deslagging station,ladle furnace,vacuum degasser tank, strong stir-powder-injection station and wire injection station.The gas emisions are captured similarly to the BOF.The particulate emissions are collected by baghouses, exept for vacuum degassing systems,which have steam ejectors and condensers 5. Ferroalloy Production: Control of pollution A ferroalloy is an alloy of iron and one or more other elements such as Si, Mn, and Cr. Silicon is used for deoxidation in steel and as an alloying agent in cast iron. Manganese is essential to counteract the harmful effect of sulfur in the production steels and cast iron. Chromium provides corrosion resistance to stainless steels. Nickel, molybdenum, cobalt, titanum, vanadium and the rare earth are also added as ferroalloys. A variety of furnace types produce ferroalloys: submerged electric arc furnace (SEAF), induction furnace, electrolytic cells, etc. About 25 percent of all ferroalloys are produced in SEAF. The SEAF ‘s products include: silvery iron (15-22 per cent Si), ferrosilicon (50 per cent Si), ferrosilicon (65-75 per cent Si), FeSi (90 per cent Si), high carbon (HC) ferromanganese, HC ferrochrom, silicon/manganese/zirconium (SMZ), etc. A typical reaction producing ferrosilicon (4) is: FeO3 + 2SiO2 + 7C  2FeSi + 7CO

(4)

The reactants in SEAF process consist of metallic ores (ferrous oxides, chrome oxides, etc.) a reductant (coke, coal, etc.) and flux, usually-limestone. In the SEAF the carbon source reacts with the metal oxides to form CO and to reduce the ores to base metal. There is particular matter from all operations during ferroaloy production: raw material handling, smetling, tapping and product handling. The organic emissions are generated exclusively from the smelting operations. Carbon monoxide is formed as a byproduct of the chemical reaction between oxygen in the metal oxides of the charge and carbon contained in the reducing agent. The head-induced fume consists of the oxides of the products being produced from the reducing agent. The fumes are enriched by silicon dioxide, calcium oxide, and magnesium oxide, if present in the charge. In an open EAF, all CO and much of the organic matter burn with the induced air at the furnace top. The remaining fume, captured by hooding above the furnace, is directed to a gascleaning device. Two emission capture systems, not usually connected to the same gas cleaning installations are necessary for covered furnaces. A primary capture system withdraws gases from the furnace cover, a secondary system captures fumes released around the electrode seals and during tapping. Scrubbers are used to control exhaust gas from sealed furnaces. This gas contains a substantial percentage of the organic emissions, which are much greater for covered furnaces then open furnaces. The gas from sealed and mix sealed furnaces is usually flared at the exhaust of the scrubber. The CO-rich gas is used as a fuel in sintering and kilns. The efficiency of flares for the control of CO and the reduction of VOC is estimated to be greater than 98 per cent. Fumes are generated also in tapping. It is usually conducted during 10 to 20 per cent of the furnace operating time. The most of fumes are a result of induced heat transfer from the molten metal (slag) as it contacts the runners, ladles, casting beds and ambient air. Some plants capture these emissions to varying degrees with a main canopy hood. Other plants employ separate tapping hoods ducted to control device. After furnace tapping is completed, a reaction ladle is used to adjust the process by oxidation, chlorination and gas mixing. Reaction ladle emissions are often captured by the tapping control system. Approximately 50 per cent of ferroalloy devices have a control for dust emissions. Dust generated from raw material storage may be controlled by several methods: sheltering storage pile from the wind with block walls or plastic covers. Dust generated by crushing, sizing and drying is captured by collection devices, such as cyclones, scrubbers or bag houses. 6. Rolling: Control of Pollution Forming processes convert solidified steel into products useful for different industrial purposes. There are a numbers of steel-forming processes, including forging, pressing, drawing, extruding, but the most important one is rolling. Rolling operations are usually subdivided into hot working and cold working. Semi-finished form (slabs, blooms and billets) are made by the ingot process or the continuous casting process. In the ingot method, the finishing stages of steel making begin when ingots are lowered into furnace called soaking pits that reheat them to the temperature of rolling. The ingot is rolled in a primary mill into semi-finished slabs or into rectangular shapes called blooms. In the continuous casting process, steel is poured directly into a tundish, which feeds a curved mold where the steel is solidified directly into semi-finished products. In this case the end products, also, are slabs, blooms, or billets. Shaping by rolling consist of passing the steel between two rolls that revolve at the same speed, but in opposite direction. During hot rolling the steel is heated to

2300oC. All rolling parameters such as temperature, thickness, width, speed of rolling are computerized. Air emissions from hot rolling mills consist of water vapor from scale breaking or metallurgical water spray and are usually uncontrolled. There are potential emissions from rolling sollution aerosols that are localized to the rolling stand, as well as small pieces of scale that may become airborne. Steel rolled on the hot strip mill can be fed into a cold rolling mill. Without reheating the cold mill rolls the steel under great pressure to precision thickness and specific surfaces. This mill exhibits MACT and is expected to release minimal quantities of pollutants because of the high level of control devices. The per cent of control by different measures in the major processing steps is following: PM from pinch roll leveler, flash butt wilder and tension leveler - 99 by bag houses; HCl vapor from pickling - 99 by scrubbers; spray of water and oil - from tandem cold mill - 80 by mist eliminator; alkali mist - from electrolytic cleaning - 95 by air washer; oil aerosol - from electrostatic oiler - 90 by mist eliminator. In hot and cold rolling, one can expect NOx emissions from combustion boilers, reheat and annealing furnace. These emissions are controlled generally by reducing flame temperature by means of: flue gas re-circulation from the boiler outlet into a wind box; low turbulence burner, which rapidly radiate the heat; allow heat release furnace, which absorb energy from the flame rapidly or by expensive post combustion method - SCR, where ammonia is used as reducing agent in reaction with oxides of nitrogen in the presence of catalyst to form N2 and water. Scarfing. Whatever the production technique, the blooms, billets or slabs undergo a scarfing which removes surface defects before shaping or rolling. Scarfing may be performed by a machine applying jets or oxygen to the surface of hot semi-finished steel or with torches by hand on cold semi-finished steel. The flame is used to melt the steel surface while the oxigen stream propels the oxidized product from the surface.The device of hot scarfing is placed before the slab or bloom shears or after the roughing or first billets mill. The device scarfer removes defects up to 4.5 mm which is sufficient to remove defects such as rolled seam and light scabs. During this activity, emissions are produced when molten steel is poured into ingot molds, and when semi-finished steel is machine or manually scarfed. The smoke of scarfing machine contains some solids, steam and gases. The submicron particles give the smoke a yellowishbrown color. Smoke gas contains (per cent): 23.0 - O2, 76.5 - N2, 0.12 - H2, and 0.22 - CO2. Pollutants emitted are iron, silicon, manganese and other oxides. The teeming emissions are rarely controlled. The machine scarfing generally use as ESP or water spray scrubbers for control. Most hand scarfing is uncontrolled. The devices used for the smoke-removal system shoud be abrasion and corrosion resistant in accordance with the nature of smoke and the composition of steel scarfed. Pickling. Pickling is a process of removing scale by contacting steel with acid solution. During the hot rolling of steel in air, an oxide scale forms that must be removed before processing procedures. Rods, bars and tubing are immersed in tanks containing sulfuric acid solutions. For alloy steel the same operation requires the use of nitric or hydrofluoric acids. Concerning the pollution a droplet of acid is formed during hydrogen evolution and the spray and water vapor are present in the air. When a hydrochloric acid is used, a hydrogen chloride vapor is also present. Scrubber and air exhaust systems are used to recover acid components. The water from the scrubber is used for makeup an addition to the pickling tanks and the waste acid solution can be regenerated or treated to prepare iron salts for different industrial use. A performed by Green Technology Group (USA) "Pickliq" process combines diffusion

dialysis, energy transfer and low-temperature crystallization to provide efficient recovery of acids for reuse in acid pickling operations. The system produces a high-quality by-product of ferrous sulfate salt suitable for sale. 7. Iron Foundries: Control of Pollution The iron foundries produce a high - strength casting products for transportation manufacturing and industrial machinery. Iron foundries cast different type of iron: grey iron, ductile iron, white iron. Cast iron is an Fe-C-Si alloy, containing from 2 to 4 per cent C, from 0.25 to 3 per cent Si, and varying percentages of S, P an Mn. Sometimes are used the following additives: Ni, Cu, Cr, Mo, Ti, fluorspar, etc. Half of the iron castings were used by automotive and truck manufacturing industry, while approximately 50 per cent of ductile iron castings were pressure pipe and fitting. The major operations are raw material handling, melting, mold and core preparation, and casting. The handling operation consists in the conveying of raw materials to the furnace: metals (pig iron, iron and steel scrub); fluxes (carbonates, carbide compounds and fluoride) and fuel (coke, coal, oil, NG). The all raw materials are added to the melting furnaces directly. For induction furnaces the scrap must be pretreated to remove grease and oil by means of solvents, centrifugation, or by preheating. The fugitive PM from the handling and preparation operations can be controlled in the point of disturbance by routing air from enclosures through bag houses or wet collectors. The preparation of scrap with heat emits smoke, CO, and organic compounds, while the utilization of solvents degreaser emit organics. About 90 per cent of the organics and CO are removed by afterburners and catalytic incinerators. The basic melting operations are charging, melting, refining, removal of slag and molding. The cupolas, electric arc, and induction furnaces are most widespread in iron foundry. Cupola. The incomplete combustion of coke causes CO and SO2. According to American Foundrymen’s Society the average emissions from an uncontrolled cupola were from 6 kg to 7.7 kg of particulate per melted ton. The dust composition and amount depend on the cupola types. The dusts include some or all of the materials: Fe, Si, Mg, Mn, Ca, Zn oxides, Cd and Pb. The fluorine emitted cause corrosion with dust collectors. When CO2 reacts with water vapor, the carbonic acid formed cause corrosion as well. Scrubbers and bag houses are used to remove PM and achieve efficiencies of 95 and 98 per cent, respectively. The afterburner oxidizes CO and burns organics and tars. Teflon-coated glass-fiber bags are used on a cupola because of their high temperature resistance. Catridge collectors and pulse-jets can also be used to collect pollutants from sand and casting cleaning operations. In comparison with other melting furnaces, cupola emit the most hazardous organic and inorganic constituents. Arc and induction melting furnaces. Electric arc furnaces are large, steel welded cylindrical vessels equipped with a removable roof through which three carbon electrodes are inserted. During melting in electric arc furnace, metal and mineral oxides generate PM by the transformation of mineral additives and vaporization of iron. CO results from combustion of graphite and carbon added to the charge. Hydrocarbons result from vaporization and incomplete combustion of oil remaining on the charged scrap. The PM is removed by bag houses and scrubbers. Typical dust loading from EAF range from 4.5 to 6.8 kg per ton melted. In the induction furnaces the heating and melting occur through low-, or high - frequency alternating current. These furnaces have lower emissions per ton of melted metal and as result, in spite of lower capacity, they have supplanted cupola in many foundries.

Pouring, Casting, and Finishing. Particulate emissions can be generated during the treatment and inoculation of molten iron before pouring. The addition of Mg to molten iron to produce ductile iron causes a reaction between the Mg and molten iron with emissions of magnesium oxides and metallic fumes. Some techniques, such as the tundush method, result in a considerable diminution of the emissions than others. The emissions from pouring consist of metal fumes, CO, organic compounds and particulates evolved from the mold and core materials. Arsenic, Cr, halogenated and aromatic hydrocarbons are released in the refining process. The pouring emissions are captured by a collection system and the treated gases are vented to the atmosphere. Emissions continue as the molds cool and during the shakeout operation. The major pollutant emitted in mold and core production is particulates from sand preparation, sand mixing with additives, and mold and core forming. Organics, CO, and particulates are emitted from core baking and organic emissions from mold drying. Bag houses and scrubbers are used to remove the particulate from mold and core production. Organics and CO emissions are controlled by afterburners and catalytic incinerators. In addition to organic binders, mold and cores may be held together in the desired shape by means of a organic polymer network. This material undergoes thermal decomposition when exposed to the 1400o C. At this temperature occurs pyrolysis of the binder which results in different free radicals which recombine to form a wide range of chemical compounds. Emissions during pouring include decomposition products of PM, resins and organic compounds. Finishing operations emits PM during the removale of burrs, gates and risers, and during shot blast cleaning. These particulates consist of iron, iron oxide and abrasive media. Cyclon separators and bag houses are controled these emissions. 8. Steel Foundries: Control of Pollution Steel foundry produces steel castings for a large utilization in machinery, transportation and many other industries. Steel castings are divided into 3 types: carbon steel, low-alloy steel and high-alloy steel. The major operations of a steel foundry are: raw materials handling, melting, alloying, molding, casting and finishing. Raw material handling operations include receving, unloading, storing, and conveying all raw materials for the foundry. Some of the raw materials used by steel foundries are iron and steel scrap, foundry returns, metal turnings, alloys, carbon additives, fluxes (limestone, soda ash, flourspar and calcium carbide), sand, sand additives and binders. These raw materials are received in ships, railcars, trucks, and containers, and are transferred by trucks, loadrs, and conveyors to both open- pile and enclosed storage areas. They are then transferred by similar means from storage to the subsequent processes. Metal melting process operations include: scrap preparation; furnace charging, in which metal, scrap, alloys, carbon, and flux are added to the furnace; melting, during which the furnace remains closed; backcharging, which is the addition of more metal (alloys); refining by oxidizing slag or by oxidizing and reducing slagging operations; oxygen lancing into the molten steel to adjust the chemistry of the metal and speed up the melt; and tapping the molten metal into a ladle or directly into molds. In steel foundry the electric furnaces are used exclusively for melting steel. There are 2 types of electric furnaces: direct arc and induction. A small per cent of the secondary steel industry uses crucible and pneumatic converter. In the end of the melting process, the molten metal is tapped and poured into a ladle. The molten metal may be treated in the ladle by adding alloys and other chemicals. The treated metal is then poured into molds and allowed to cool. When cooled, the castings are placed on a vibrating grid and the sand of the mold and core is shaken away from the casting. In the cleaning and finishing process, burrs, risers, and gates are

broken or ground off to match the contour of the casting. Afterward, the castings can be shotblasted to remove remaining mold sand and scale. Emissions from the raw materials handling operations are fugitive particulates generated from receiving, storing, and conveying all raw materials for the foundry. These emissions are cotrolled by enclosing the major emission points and routing the air from the enclosures through bag houses. Emissions from scrap preparation consist of smoke, organics, and CO if heating is used and consist of hydrocarbon if solvent degreasing is used. In this case catalytic incinerators and afterburners of approximately 95 percent control efficiency for CO and organics are used. Emissions from melting furnaces are particulates, carbon monoxide, organics, sulfur dioxide, nitrogen oxides, and small quantities of chlorides and fluorides. The particulates, chlorides, and fluorides are generated by the flux. Scrap contains VOC and dirt particles, along with a oxidized phosphorus, silicon, and manganes. In addition, organics on the scrap and the carbon additive increase CO emissions. There are also trace constituents such as nickel, hexavalent chromium, lead, cadmium, and arsenic. The highest concentrations of furnace emissions occur when the furnace lids and doors are opened during charging, backcharging, alloying, oxygen lancing, slag removal, and tapping operations. These emissions escape in the furnace building and are vented through roof vents. Controls for emissions during the melting and refining operations focus on venting the furnace gases and fumes directly to an emissions collection duct and control system. Controls for fugitive furnace emissions involve either the use of building roof hoods or special hoods near the furnace doors, to collect emissions and route them to emission control system. Emission control systems commonly used to control particulate emissions from electric arc and induction furnaces are bag filters, cyclones, and venturi scrubbers. Molten steel is tapped from a furnace into a ladle. Alloying agents such as aluminium, titanium, zirconium, vanadium, and boron can be added to the ladle. Ferroalloys are used to produce steel alloys and adjust the oxygen content while the molten steel is in the ladle. Emissions consist of iron oxides during tapping in addition to oxide fumes from alloys added to the ladle. The major pollutants from mold and core production are particulates from sand reclaiming, sand preparation, sand mixing with binders and additives, and mold and core forming. 9. Concluding Remarks In the iron and steel industry environmental issues now command center stage. Decisions to maintain or to modify current sinter, coke, iron and steel utilization and to develop sustainable environmental strategy must positively respond to public and regulatory concerns over how iron and steel technology may adversely affect human health and local, regional, and global ecosystems. Related Chapters Click Here To View The Related Chapters Glossary BaP : benzo(a)pyrene BOD : Biological Oxygen Demand BOF : Basic Oxygen Furnace

COD : Chemical Oxygen Demand DRI : Direct Oxygen Reduction EAF : Electric Arc Furnace ESP : electrostatic precipitator Gt : giga tons (109 tons) KMnO4 : potassium permanganate LAER : Lowest Achievable Emission Rate MACT : Maximum Achievable Control Technology MCS : Multi-Chamber-System : micron (10-6)  NG : natural gas NR/HR : CO-Non Recovery/Heat Recovery-Coke Oven PAH : polycyclic organic hydrocarbon PM : particulate matter POM : polycyclic organic matter : battery systems with enlarged flues and crossover gas PVR circulation. SCR : selective catalytic reduction SCS : Single Chamber System VOC : volatile organic matter Bibliography Wotte J., Wolfgang A. H. and Kramer B.J. (1966). Environmental Engineering and Pollution Prevention, NATO ASI Series ,2. Env.- Vol. 18, , pp. 43-62 . Dordrecht, The Netherlands: Kluver Academic Publisher [Contains useful descriptions and evaluations of contamination problems on industrial areas in connection with techniques for clean-up]. Conners A. and Mullen J. ( 1980). Development in Coke-Oven Emission Control. Iron and Steel Engineer Vol. 57, 6, pp. 33-39. [ This represents one of the plausible aspects to the study of coke oven emissions]. Eliot A.C. and Freniere A.J. (1962). Metallurgical Dust Collection in Open Hearth and Sinter Plant. Canadian Mining and Metallurgical Bulletin Vol.55, 10, pp. 724-731.[ This presents some data concerning hazardous emissions from open hearth and sinter facilities]. Bender M. and Rostic L.F. (1987). Emission control aspects of modern EAF steel making. Iron and Steel Engineer, Vol.64, 9, pp. 22-25. [ This work presents an informations concerning EAF ‘s emission control: direct evacuation control(DEC) systems, canopy hoods systems, furnace enclosures, different types of bag houses]. Zunkel A.D. (1997). Electric arc furnace dust management. Iron and Steel Engineer, Vol. 74, 3, pp. 33-38. [ This work includes some interesting data concerning economics and utilization of different dust recycling facilities in the world]. Lungen H. B. and Steffen R. (1998). Comparison of Production Costs for Hot Metal and Sponge Iron. Cokemaking International, Vol. 10, 1, pp. 28-34.[This article shows the current state of development of the ore reduction processes, and a comprehensive discussion of new processes of direct reduction iron(DRI)]. Hullinger J.P., Skubak J., Hawthorne D.S. and Swales A.C. (1997). Innovative environmental investigation techniques for iron and steel facilities. Iron and Steel Engineer, Vol 74, 2, pp.54-59. {This paper includes the strategy of investigation of environmental aspects in iron and steel industry]. Kotzin E. L. (1989). Metalcaster’s Reference and Guide, 2nd ed., American Foundrymen ‘s Society, pp. 18-47. Des Plaines, IL. [This book introduces all the essential aspects of pollution control mesures in the casting operations].

Greenfield M.S. (1984). Environmental problems in iron and steel industry. Handbook of air pollution technology, Vol. 2 (ed. Calvert S. and Englund H. M.), pp. 24-91. New York, Chichester, Brisban: John Wiley & Sons. [This book provides some aspects of the environmental problems in: sintering, cokemaking, blast furnaces, basic oxygen process; the trends in electric arc furnace emission control; environmental assesment of iron casting] Doushanov D.L. (2000). Clean technology of the coke oven industry : a way to a sustanable economic development. JOURNAL of ENVIRONMENTAL PROTECTION AND ECOLOGY, Special Issue,pp.5-9 [ This article includes some environmental aspects of alternative technologies and the situation in the coke plant "Kremikovtzi"] Doushanov D.L. (2002). Environmental problems and control of pollution in iron industry. JOURNAL of ENVIRONMENTAL PROTECTION AND ECOLOGY, Vol 3, 2, pp.92 – 100 [ This paper includes the data concerning environmental problems in different countries and Bulgaria ] Web site of the US EPA (http//www.epa gov.) [Provides information for many problems, covered in this chapter]. Biographical Sketch Doushko Doushanov is Charman of the Bulgarian Society of Petrochemists, Sofia, Bulgaria.His graduate thesis ilustrated the mathematical simulation of large scale technological systems. He has worked several years in Metallurgical works "Kremikovtzi", Departement of Fuel-Bulgarian Academy of Sciences, as associate professor in the National University in Algeria (Chemistry and Technology of Petroleum). He has worked also as consultant to the UNIDO on cokemaking and metallurgical problems. In this capacity he has contributed to the real improvement and protection of the environmental media - air, water and soil from the iron and steel plants. His interests include also the Petrochemical Processes, Gazification, Pyrolysis (Adsorbents), Picling, and Rolling. The results of Doushanov, s researches have been reported in numerous scientific publications also in the Official Journal of Balkan Environmental Association ( B.EN.A.).

To cite this chapter D. L. Doushanov, (2006), CONTROL OF POLLUTION IN THE IRON AND STEEL INDUSTRY, in Pollution Control Technologies, [Eds. Bhaskar Nath, and Georgi St. Cholakov], in Encyclopedia of Life Support Systems (EOLSS), Developed under the Auspices of the UNESCO, Eolss Publishers, Oxford ,UK, [http://www.eolss.net] [Retrieved July 6, 2007]