Strategy to Reduce Unintentional Production of POPs in China (Sino-Italian Project funded for UNIDO POPs Program)

-Sector Report on Iron & Steel Industry 2005-

1. GENERAL INFORMATION ON THE INDUSTRIAL SECTOR The iron and steel industry is highly intensive in materials and is a major energy producer and consumer. The sector has special requirements for technologies, too. It has also an important environmental relevance in terms of releases and impacts to the various environmental media, including a global significance regarding CO2 emissions. Global steel production has grown exponentially in the twentieth century, rising from 28 million tons at the beginning of the century to a world total of 757 million tons in 1995. During this period, the steel industry developed in Western Europe and the USA followed by the Soviet Union, Eastern Europe and Japan. Since the oil crisis of 1974-75 and until 1995, production of crude steel was virtually stagnant worldwide, with production of around 700-750 million tons per annum. From 1995 to 2005, growth in world crude steel production rose to 848 million tons in 2000 and up to 1,132 million tons in 2005. This strong growth in steel production was largely a result of rising income and strong demand for steel in developing countries, particularly in East Asia, China and South Asia. Steel consumption in developed countries has nowadays reached a stable level. The apparent steel consumption per capita in the world in 2005 was 189 kg/capita, varying from 43.3 kg/capita in Africa to 398.9 kg/capita in the European Union (15). 1.1. Applied processes and techniques in the iron and steel industry Steel is manufactured by “integrated” and “non-integrated” producers. Integrated producers make steel from mostly virgin raw materials including iron ore, coal, and limestone. Coke is produced by heating coal in the absence of oxygen at high temperatures in coke ovens. Pig iron is then produced by heating coke, iron ore, and limestone in a blast furnace. Pig iron from the blast furnace is finally converted in steel in basic oxygen furnaces (BOFs). Non-integrated producers make steel mostly by melting and refining ferrous scrap at smaller scale facilities (often referred to as minimills). Non-integrated steel plants generally use electric arc furnaces (EAFs), where the scrap is melted and refined by passing an electric current from the electrodes through the scrap. Some non-integrated steel mills also use high-quality iron materials such as pig iron or direct-reduced iron along with scrap. Steel produced at steel mills can be classified as carbon steels, alloy steels, and stainless steels. Carbon steels owe their properties to varying concentrations of carbon. Alloy steel contains specified alloying elements added to impart unique properties to the steel. Stainless steels are corrosion resistant and heat resistant; the principal alloying elements for stainless steel are chromium, nickel, and silicon. Depending on final product specifications, the molten steel undergoes various refining steps prior to casting, hot forming, and finishing operations. Some of the integrated steel plants also operate cold forming (rolling mills), surface treatments, and finishing processes. The product range may include continuous cast billets, blooms, or slabs, long or bar mill products, reinforcing steel, round and square bars, and flat rolled steel including plate, strip, and sheet. The iron and steel industry has been characterized by the dominance of integrated steel production over the electric arc furnace (EAF), which accounted for respectively 65.4 per cent and 31.7 per cent of the world production of crude steel in 2005. Electric arc furnace steel production gradually increased over the last years. Nevertheless, the blast furnace-basic oxygen furnace route is predicted to remain the dominant means of steel production. Moreover, more than half of the market for quality steel products still remains beyond minimill capability.

1.2. Industrial process description. Raw materials handling. The iron and steel industry involves high input mass streams of raw materials such as ores, pellets, scrap, coal, lime, limestone, additives and auxiliaries. These materials are usually transferred to the site in bulk carriers by road, rail or water transport. Both these and the intermediate products, such as coke and sinter, have to be stored on stockyards or silos and transported to the individual processing plants, usually by conveyor belts. Coke-making. Coke-making is the process of conversion of coal in metallurgical coke. Coke is needed as the primary reducing agent in blast furnaces to reduce iron oxide to iron. Coke also acts as a fuel, provides physical support and provides a porous matrix structure in the blast furnace. Since coal cannot fulfill all these functions, it must be converted to coke. There are two types of coke-making plants: by-product recovery and non-recovery. In byproduct coke plants, metallurgical coke is produced by distilling coal in refractory-lined ovens at high temperatures in the absence of air. In by-product coke operations, the gas that is generated from the coal distillation process is collected as a gas called coke oven gas (COG). COG is used as a by-product fuel with about half the heating value of natural gas. Prior to distribution as a fuel gas, part of the raw COG is processed in a by-products plant where some of the components are removed. In non-recovery coke plants, coal is made into coke in negative pressure, high temperature, dome-shaped coke ovens. Volatile by-products generated during the coke-making process are contained in the ovens and are thermally destroyed at the high temperature inside the oven. Because non-recovery plants combust all materials evolved from the coal, there are no by-products recovered. Sintering Process. Sintering is the process used to convert iron-rich materials (e.g. fine-grained iron ore, mill scale, dust, sludge) into a porous material with the size and strength characteristics necessary for feeding into the blast furnace. The sinter process is generally performed on a continuously moving grate or “strand” that transport a layer of pulverized ferrous material, intimately mixed with additives (limestone, dolomite) and fuel materials (coke breeze, fine coal). Raw materials are mixed in a specified ratio and blended prior to the sintering operation. At the start of the sintering operation the ore blend is transferred as a bed of uniform thickness to the start of the sinter grate and ignited. The combustion is started by gas burners and subsequently sustained by the fuel. Air is drawn down through the moving bed into suction wind-boxes with the purpose to allow the front of combustion to move downward and to get the combustion on the whole thickness of materials. The combustion process produces enough heat (1,300-1,480 °C) to allow the superficial fusion of the particles and their agglomeration into a porous clinker termed ‘sinter’. As it is produced, sinter falls off the end of the grate. The solidified sinter is hot crushed, then air-cooled, cold crushed and finally screened. Pieces 5-50 mm are sent to the blast furnace. Fines measuring less than around 5 mm are separated and recycled back to the process. Briquetting-pelletising. Briquetting is a different agglomeration process used to recycle and reuse fine materials recovered from iron and steel operations that otherwise could not be charged to blast furnaces. Materials are similar to those charged to sintering operations, although they are usually formed with the use of a binder and do not possess the strength of sintered products. Blast Furnace Ironmaking. In ironmaking, blast furnaces are used to chemically reduce iron oxides into liquid iron called “hot metal”, which is subsequently charged to basic oxygen steel-making converters.

The blast furnace is a large steel stack lined with carbon-type refractory blocks. Blast furnaces usually range between 20 and 40 meters in height, with hearth diameters between 6 and 14 meters. The rated capacity of blast furnaces ranges from under one million tons per year to over four million tons per year. The raw materials charged to the top of the blast furnace include iron bearing materials (iron ore lumps, sinter and/or pellets), reducing agents (coke), and additives (slag formers such as limestone). Hot blast (preheated air) at temperatures between 850 and 1,250 °C and injected fuel (e.g., oil, pulverized coal, natural gas, coal tar) are blown into the bottom of the furnace through a bustle pipe and nozzles called tuyeres located around the circumference of the furnace. The hot blast passes up through the raw material mass and reacts with the coke to produce the reducing agent, carbon monoxide. The reducing gases ascend through the furnace to reduce the iron-bearing materials to liquid iron. The limestone combines with sulphur and other unwanted impurities to form slag. Both the liquid iron and slag are collected on the hearth and are periodically tapped from the furnace. The molten iron is tapped into refractory lined ladles mounted on railway trucks, known as torpedo cars due to their shape. Steel-making - Basic Oxygen Furnace (BOF). The BOF steel-making process involves the conversion of the hot metal from the blast furnace, which contains approximately 4 % carbon, into steel, which typically contains less than 1 % carbon, through the injection of pure oxygen into the liquid iron bath. The conversion takes place in a refractory-lined, pear-shaped vessel. The BOF process is semi-continuous with a complete cycle taking about 45 minutes. In steel-making operations, one-quarter to one-third of the furnace charge is steel scrap that is charged into the furnace before the liquid iron is poured from a ladle into the furnace. Fluxes such as lime or dolomite are added to the bath to produce slag. Oxygen is then injected into the molten bath either through the top of the furnace (top blown), bottom of the furnace (bottom blown), or both (combination blown). The reactions between silicon, carbon, and oxygen are strongly exothermic and cause the temperature in the vessel to rise. During the process the carbon is oxidized and released as CO and CO2. Silicon, manganese, and phosphorus are also oxidized and captured in the slag formed by the fluxes. Once the desired steel composition and temperature has been achieved, the oxygen lance is removed and the slag is separated from the molten steel. The liquid steel is tapped into a refractorylined ladle for transfer to the ladle metallurgy station and to the casting section. Steel-making – Electric arc Furnace (EAF). The electric arc furnace (EAF) steel-making process is generally used for melting and refining a metallic charge of scrap to produce low tonnage carbon, high alloy, stainless steels and other high value specialty steels. Steel scrap comes from within the plant, customers and scrap recyclers (automobiles, appliances, containers, demolition sites, and other sources). In addition to steel scrap, the charge may include hot metal, pig iron and direct reduced iron (DRI). An electric arc furnace is a cylindrical vessel, internally lined up with refractory while watercooled panels make the upper part of the walls. A dome-shaped removable roof, provided with one or three graphite electrodes, closes the vessel. The production of steel in an EAF is a batch process. The main processes can usually be split into the following steps: scrap charging, melting, refining, deslagging, and tapping. Scrap is charged from bottom-opening buckets into the open furnace shell. Additional inputs are fluxes (e.g. limestone or dolomite), coke, de-oxidants and alloying elements. The heat derived from the alternating current (AC) or direct current (DC) electrical power is supplemented by oxy-fuel burners. Pure oxygen is injected through water-cooled lances to speed up the process. Phosphorus, silicium, manganese and other elements contained in the scrap are oxidized and incorporated in the slag. At the end of the process, the slag is removed and the furnace is tilted for tapping the melted steel into a refractory-lined ladle. Nowadays, a cycle (tap-to-tap) lasts around 45-60 minutes. Vacuum Degassing. Vacuum degassing is a batch process in which gases (mainly oxygen and hydrogen) are removed from molten steel to produce steel of high metallurgical quality.

Ladle Metallurgy and Secondary Steel-making. Ladle metallurgy and secondary steel-making are steel refining operations that molten steels undergo at atmospheric conditions before casting. Common types of ladle metallurgy and secondary steel-making include argon or nitrogen bubbling and stirring, argon-oxygen decarburization, deoxidation, magnetic stirring, electroslag refining and alloy addition operations. Casting. Casting converts molten steel into a semi-finished product or shape that is suitable for further processing. There are two main types of casting operations: continuous casting and ingot casting. Because continuous casting directly forms the molten steel into blooms, billets, or slabs, increasing productivity and conserving energy, continuous casting has replaced most ingot casting operations. In the continuous casting process, molten steel is poured from the ladle into a refractory-lined vessel called tundish. Stoppers or sliding gates in the base of the tundish are opened to control the flow of the molten metal into a water-cooled copper mould, where the metal partially solidifies. After passing through the water-cooled mould, the partially solidified product is withdrawn through the bottom of the mould and passes into a secondary cooling zone through guiding rollers where solidification of the semi-finished product is completed with the help of water sprays. The product then passes into the cut-off zone where it is cut to the desired length. The other main casting operation type is ingot casting, in which molten steel is poured into ingot moulds. After cooling, the solidified ingots are stripped out of the moulds. The ingots are then heated and rolled or forged. Ingot casting is used typically for small, specialty batches and for certain high-value applications. Hot Forming processes. Hot forming processes take place at integrated mills or at stand-alone hot forming mills. Hot forming is a process in which preheated, solidified steel is reshaped through a series of forming steps in which mechanical pressure is applied through electrically powered rolls. Metallurgical properties of the steel are changed, too. In general, section mills reduce billets to form rod, bar products, structural shapes or other forms. Pipe and tube mills form seamless products from round billets and butt-welded products from strips. Flat mills, specifically hot strip mills, are the most common type of hot forming mills. Hot rolled strip is formed from a slab, which is heated in one or more furnaces. The slab then rolls through roughing stands until it reaches a desired thickness. Forging is another type of hot forming operation in which steel shapes are produced by hammering or by processing in a hydraulic press. Forging operations can be conducted on cold, warm, or hot steel. Secondary forging processes may also be conducted on steel shapes. Cold forming processes. Some flat-rolled products, primarily steel strip or sheet, undergo further processing by cold forming. The steel strip or sheet is cold reduced at ambient temperatures by compression between rolls to the required thickness and specifications. Cold forming is mainly performed in order to impart desired mechanical and surface properties in the steel, such as hardness. Cold rolling mills modify steel sheet properties, including strength, surface hardness, and thickness. Temper mills primarily improve flatness, alter mechanical properties and improve the finish of steel sheet. Some specialty products may be annealed after the cold rolling. Steel is heated at a designated temperature and then cooled at a designated rate through a batch or continuous process. Through the annealing process, the steel modifies its metallurgical properties and the desired mechanical and surface properties in the steel are obtained. Finishing. The type of steel finishing operation is closely related to the type of steel processed. Acid pickling, descaling, acid and/or alkaline cleaning, surface coating, and electroplating are usually performed.

Acid pickling and descaling operations remove oxides and scale from the surface of hot-formed flat-rolled product prior to further processing. Alkali cleaning is used to remove fats and oils that remain on the steel surface from the cold forming operation. Steel coating operations are performed to improve resistance to corrosion of steel and to improve appearance of some products. Applied coatings may be metallic or nonmetallic. Metallic coatings are applied by immersing pre-cleaned steel into a molten bath of coating metal such as tin or zinc (hot galvanizing) or by electrodeposition (zinc, nickel, tin, chromium, and copper coatings). Non-metallic coatings are normally organic compounds in the form of powders, paints, films, and liquids and are applied by brushing, rolling, spraying, or immersion. Utilities. Utilities include boilers, air compressors, liquid oxygen plants, fuel storage and distribution, electrical power distribution, etc. The most significant emissions are from the boiler fuel combustion. Boiler fuels include coke oven gas, blast furnace gas, natural gas, and heavy fuel oil.

2. PROFILE OF THE INDUSTRIAL SECTOR IN CHINA Driven by the demand in domestic and world markets and supported by the economical growth policy of the country, steel production and consumption grew steadily in China. Since becoming the world’s largest steel producer in 1996, crude steel output in China reached 349.4 million tons in 2005 (30.9 % of the world crude steel production) and 422.7 million tons in 2006 (34% of world production). This growth is expected to continue over the next few years due to the continued growth in domestic demand. Most of the companies operating blast furnaces are located in the North and Northeast regions, where coal and ore mines are located. However, the average grade of China's iron ore is 32.7 per cent while that in Brazil, Australia and South Africa exceeds 55 per cent. Iron ore production in China was 588 million tons in 2006. Forecast for 2007 is 805 million tons (equivalent to 383 million tons of grade 65 % iron ore). In 2006, China imported 325 million tons of iron ore and the forecast is 370 million tons (+ 14.2 %) for 2007 and 410 million tons (+ 10.8 %) for 2008. Pig iron output was 330.4 million tons in the year 2005 and 404.2 million tons in 2006. In 2006, the national production of coke reached 297,68 million tons, with a relative increase of 17.1 % compared to the country production of the previous year. China's major coke producers are located in the provinces Shanxi, Hebei, Shandong, Henan and Liaoning. Approximately 48 new coke furnaces have been commissioned in the year 2007, bringing an additional capacity of 25 million tons to the country. By the end of 2008, 25 million tons of additional coking capacity is expected to be added. China eliminated 15 million tons of out-of-date coke production capacity in 2006. The highest geographic concentration of finished steel producers is in the East and South Coast. About 60 % of the Chinese steel-making capacity is located in the Province and Municipality of Liaoning, Hebei, Beijing, Tianjin, Shandong, Jiangsu, Shanghai, Zhejiang, Fujian, Guangdong and Hainan. While China is the world's largest producer of steel, it is also the world's largest consumer of steel with an apparent consumption of 350.17 million tones (2005). The United States ranks as the second largest consumer of steel at 113.26 million tons, followed by Japan at 82.9 million tons. The apparent consumption of steel per capita in China is approximately 250 kg. Considering a steel consumption of 400 kg per man per year to be a fair level of economic development, the per capita steel consumption is below that of the developed countries. Indeed, while China has been progressively raising steel production for many years, it has also been importing substantial quantities of steel. It is only recently that China has become an exporter of steel. This indirectly means that China has also reached a level of production saturation and its steel industry is more likely will go through consolidation and reorganization in coming years rather than any major expansion. China's steel industry has seen an annual growth of at least 20 per cent in production terms since the beginning of this century. The scientific and technical development strategy in China's iron and

steel industry focused on continuous casting, a more efficient forming technology than ingot casting. A large number of completely continuous casting steel mills appeared. Continuous casting has increased from about 25 % of all steel produced in 1990 to 94 % in 2004. In 2005 continuous casting throughput exceeded 330 million tons, with accounted for approximately 96 % of the steel output in China. The rapid development of continuous casting technology achieved several technological and economic benefits, amongst them an increase of the overall yield of steel produced of about 11 %. Besides the development of continuous casting technology, others key technologies have been introduced and developed in the iron and steel industry in China. The pulverized coal injection (PCI) technology in blast furnace operation increased from a PCI ratio of 51 kg/t in 1990 to 125 kg/t in 2002, providing important economic and operational benefits, first of all a lower consumption of more expensive coke (one ton of pulverized coal used for steel production displaces about 1.4 tons of coking coal), higher blast furnace productivity, and greater flexibility in blast furnace operation. At the same time, average coke ratio dropped from 557 kg/t to 415 kg/t. In 2002, the average utilization rate of blast furnaces of key large and medium enterprises reached 2.448t/m3·d, the average campaign of converters reached 4268 heats and many converters were more than 10,000 heats. Moreover, a large amount of outdated technology and equipment, such as open-hearth furnaces, were eliminated. Product structure changed and particularly the production of flat products increased rapidly under the pressure of market demand. In 1996, the total output of flat products was 29.25 Mt. It reached 50.63 Mt in 2000 and 166.9 Mt in 2005. The fast development of building construction greatly promoted also the demand of long products (concrete reinforcing bar and wire rod). The optimization of procedures greatly improved the level of technical process of China’s iron and steel industry and become a mainstream of energy conservation. Energy consumption dropped from 0.997 tce/t-steel in 1990 to 0.715 tce/t-steel in 2002. Since 1990, the structure of the steel mills has been adjusted and improved and the distribution of steel industry has been expanded and regulated. The number of steel mills with an annual output of over 1 million tons increased from 14 to 59 from the year 1990 to 2003. However, a large amount of China's iron and steel output is still produced by small or medium-sized plants. For example, in 2005 approximately 52 % of the pig iron production in China was obtained from 347 blast furnaces with an inner volume of 1000 m3 or smaller. Small blast furnaces (300 m3 in inner volume or smaller) accounted for approximately 6.3 % of the pig iron production in China in 2005. Compared with more developed steel-producing countries, the progress in size enlargement is still slow and lags behind some advanced foreign countries. It affects productivity, reduction in material and energy consumption and improvement in production stability. According to China Iron and Steel Association (CISA), 871 iron and steel manufacturing facilities were operating in China in 2005, of which 89 large and medium-size enterprises operating one or more iron or steel-making facilities. However, only 17 steel producers had an annual crude steel output of more than 5 million tons in 2005. In 2005 steel output of the top 10 steel enterprises made up 35 % of the total output, a proportion far lower than that of developed countries. For instance, in the United States the top six companies produce around 50 % of all domestic production. The percentage for the top five in Japan is 75 % and for the top three in Russia is 50 %. POSCO alone produces 65 % of Korean steel while one or two major steel producers represents almost all the production of a whole country in France, UK and Italy. Though there is a fast increment in secondary refining, the percentage of hot metal pretreatment and liquid steel refining is still far below the level in some advanced steel producing countries. This influences the improvement in casting operation and the quality of produced steel. As a developing country, China still needs to produce and consume large amount of steel. China's economy has entered a development stage that is characterized by enlargement in consumption intensity and rapid growth in urbanization and industrialization, with an increased demand of steel in building construction, automobile industry, ship-building industry, etc. In order to enhance concentration and competitiveness of the steel industry, China's National Development and Reform Commission (NDRC) released "Steel Industry Development Policies". The new policies encourage merging and restructuring of steel enterprises with the purpose to expand the scale of key enterprises and groups. By 2010 China’s number of steel making enterprises should be

reduced so as to establish two internationally competitive steel groups with 30-million-ton production capacity per year and several with 10-million-ton production capacity. The steel output of the top 10 steel enterprises should account for half of the country's total steel production by 2010 and over 70% by 2020. This will be achieved through merging or acquisitions among existing steel makers. Relatively small and inefficient steel mills will be phased-out or will join larger groups to fit into the country's sustainable development programs. The aggravation of environmental conditions has started to restrict the scale expansion of Chinese steel enterprises and the rapid growth of the industry production capacity. The Government sets forth the target asking steel-making sector to keep lowering the total pollutant emission. Building new (or expanding) high energy-consuming enterprise like iron and steel complexes or smelting plants in large or medium-size city or at its suburb will be under strict control and prohibition. New construction projects related with the iron and steel industry will be carefully straighten out. Management in investment, land utilization, environment assessment, and quality control will be strengthened in order to strictly control the market access. The Chinese steel industry has set out several priority issues, including the establishment of clean production systems through the efficient use of raw material and energy resources and environmental protection measures. The gap between China and foreign countries in view of air pollutants generated during iron and steel production process is mainly represented as follow: • • •

almost no measure taken for treatment of SO2 generated in sintering and other processes; dust content in atmospheric emissions has lowered down to 20-30 mg/Nm3 in developed countries, or even down to 10-20 mg/Nm3 in some steel complexes. However the current criteria for dust emission in China from sinter plants is still as high as 50-100 mg/Nm3; lack of effective monitoring of pollutants like dioxin, PAHs, mercury, etc.

2.1. Characterization of sinter plants in China. According to an incomplete statistic of 2005, there are 369 sintering machines in China, of which 27 large-sized (200-495 m2), with an annual sinter production of approximately 380 million tons. The technical improvement in sintering process is represented by the fact that China now can independently design and manufacture large-sized, modern sintering machine. Advanced technologies such as enhanced feed agglomeration, deep bed, high basicity and full automation control have already been widely adopted. Progress in some field has also been achieved, like high efficient de-dusting, waste heat recovery from off gas at medium or low temperature, etc. The average area of sintering machines in China is only 58 m2, much less than, for example, in Japan where the figure is 342 m2 or in the enlarged EU 25, where the 58 sintering machine (spread over 47 sintering plants with a total capacity of 127 Mt/a) have an average surface of approximately 200 m2. However, most of the plants in Europe were erected in the sixties or seventies. Compared with Japan, in China the utilization factor is 0.07 t/(m2*h) lower, the capacity utilization is 3.9 % lower, TFe is 3.6 % lower, solid fuel consumption is 7.6 kg st-coal/t higher and FeO content in sinter is 2.7 % higher. In Japan most of the sintering machines are equipped with SOx removal device and a small number is also provided with NOx removal unit. However, the implementation of this kind of equipment is just started to be applied in China. Many Japanese steel producers employ intelligent systems to control sintering process, fuel consumption and production management, but the percentage of such application is quite low in China. The technical development for sintering in China has the following objectives: • • •

increase the proportion of beneficiated burden material; increase the percentage of pellet in burden material of blast furnace (meeting the requirement of pellet > 20 % in charge mix by 2010); expedite the elimination of small (< 75 m2) sintering machine and the construction of new sintering machine larger than 180 m2;

New technologies that will be largely implemented and developed in sinter plants in China include:

• • • •

recycling of part of the waste gas from the whole sinter strand back to the surface of the strand in order to reduce pollutant emissions and save energy as well; waste-heat recovery in warm off gas from cooling machine and tail part of sintering machine to produce steam and hot water ; SOx and NOx removal technology for off gases generated in sintering and pelletizing plants. dedusting with electrostatic precipitator.

Main objectives of sintering machine in China. Year Utilization factor, t/m2*h Capacity utilization, % TFe in sinter, % FeO in sinter, % Strength of sinter, % Solid fuel consumption, kg-coal/t

2006~2010 1.4~1.6 (fine ore) 1.3~1.5 (concentrated ore) 94 59 6~7 79 45

2011~2020 1.6~1.8 (fine ore) 1.5~1.7 (concentrated ore) 97~98 60 5~6 80 40

High dust content in atmospheric emissions from sinter plants in China represents one of the main environmental issues. Average dust content in emitted waste gas from sintering and pelletizing plants is 131.5 mg/m3. With an average specific waste gas flow of 4313.7 m3/t·sinter, the average emission factor for dust emissions to air for sinter operations at Chinese sinter plants is 567 g-dust/t-sinter. In China, criteria for existing emission source (60 %) will be defined as 0.55 kg/tsinter, while for new emission sources (40 %) it will be 0.25 kg/t-sinter. 2.2 Characterization of the electric arc furnace steel-making route in China. Electric arc furnace steel-making developed in China particularly in areas with abundant steel scrap supply and low electricity price. However, due to the shortage in steel scrap and the increase in electricity cost, the percentage of steel made by electric arc furnaces started to decline since the mid of ‘90s despite of a step increase after entering the new century. Although ranking second in the world after United States, the percentage of EAF produced steel maintains far below the world percentage. China’s EAF steel output amounted only 12.9 % of the total national steel output in 2005. For comparison, in Europe 15 and in the United States, steel output by electric arc furnaces accounted, respectively, for 40.7 % and 56.0 % of national steel output in 2005. Steel scrap is an important strategic resource since it is an energy-containing resource and an environmental protective resource as well. Using steel scrap for steel-making can reduce the consumption of energy by 60 % and of water by 40 % compared with the conventional process in which steel-making comes after iron-making from iron ore. Furthermore, it considerably reduces emissions of waste gas, discharge of wastewater and production of slag by 86 %, 76 % and 7 % respectively. Also, consumption of iron and steel scrap reduces the burden on landfill disposal facilities and prevents the accumulation of abandoned steel products in the environment. In 2007, the demand for steel scrap in China will be 80 million tons. It is predicted that selfproduced steel scrap will be 27 million tons and steel scrap collected from society will be 44 million tons. Even if all steel scrap from the two sources will be used in steel-making, there will still be a shortage of 9 million tons. Considering also the steel scrap demand in foundries, the total shortage of steel scrap will be 12~15 million ton. This amount must be imported. In developed countries, old (post-consumer) scrap (scrap from the recovery of products that are no longer used or needed) account for a high percentage of used steel scrap. For instance, in the USA, recycled scrap consists of approximately 49 % old scrap, 26 % prompt scrap (produced in

steel-product manufacturing plants), and 25 % home scrap (scrap from current operations) in 2005. In China, only approximately 20 % of steel scrap is old scrap. In developed countries, the primary source of old steel scrap is the automobile. Old appliances, steel cans and construction materials are also actively recycled. In China, one important gap is the availability of car shredders for supplying shredded steel scrap. This affects not only the storage and utilization of steel scrap but also its quality and, as a consequence, the quality of liquid steel. Classification is a major problem in storage and utilization of steel scrap in China, too. Only a small number of special steel producers sort the recovered scrap for their steel-making processes. A poor classification and a mixed storage of recovered steel scrap causes a low removal of inclusion and a low utilization of valuable components such as alloying elements. A better classification of the reusable portion (including also the non-ferrous and plastic fractions) from the steel scrap shall be carried out in future to improve sorting and recycling. In recent years, addition of big amount of hot metal in the electric arc furnace steel-making process is a new fashion in China. In the electric arc furnace with more than 30 % hot metal in the charge mix, production is accelerated and the power consumption for smelting declines below 300 kwh/t. Content of unwanted elements and N2 in steel is reduced as well. Thanks to the low cost of hot metal produced by small-size blast furnace in China, steel producer with electric arc furnaces can gain a significant profit. However, the advantage of the short process routing and compact layout for EAF steel-making plants is lost owing to the small blast furnace and related iron-making sections arranged upstream the EAF. In spite of 16 EAFs in China having reached advanced world level of 0.8~1.2 million tons per year in 2003, the average annual productivity per furnace is only 170,000 t/a. The majority of the EAFs in China size approximately 30 t. For comparison, in foreign countries the size of EAFs is usually of 80~120 t. The tendency in recent years indicates an increase of the size of EAFs up to 150~200 t. Small furnaces result in low automation, low energy utilization, low productivity, low quality and stability in production and poor environment protection. The technical development for the EAF steel-making process in China in the next years will be oriented to technical research in raw material, size enlargement of the furnaces, high efficiency and automation and standardization of the process. Technological objectives will be connected with the implementation, development and diffusion of key technologies in the EAF steel-making process: • • • • • • •

scrap sorting, processing, storing and mixing; optimization of the charge mix and process technology aiming at minimum cost and high rate of smelting; clean production technology; "water zero-discharge" technology; high efficient primary and secondary de-dusting technology; slag treatment and reutilization technology; technologies for reducing emissions of dioxins, furans and benzo(a)pyrene.

Main objectives of the EAF steelmaking process in China. Period Average power consumption, kwh/t Tap-to-tap time, min Oxygen consumption, m3/t Furnace campaign, heats Others

2006~2010 400~420 ~ 65 25~30 > 600~800 Computerized operation at furnace larger than 50-t

2011~2020 < 380 ~ 55 36 > 1000

High dust content in atmospheric emissions from EAF plants in China represents one of the main environmental issues. Dust is generated during smelting in electric arc furnaces as well as during charging, oxygen blowing, deslagging and tapping. Dust is also generated during steel refining with LF and VD or other refining units. Nowadays, primary and secondary off-gases of EAFs are normally collected by means of a combination of direct suction through the 4th hole (2nd hole for a DC EAF) + "dog house" + canopy hood. After collection, off-gases are cleaned with high efficient bag filters. At present high efficient bag filters are state-of-the art for gas cleaning in EAF steel-making plants. In China, emission standards for atmospheric emission of dust from electric arc furnace are 35 mg/Nm3 and 20 mg/Nm3 for existing and new installations, respectively.

3. INVENTORY OF U-POPS RELEASES FROM THE IRON & STEEL INDUSTRY IN CHINA In the framework of the activities related to the implementation of the Stockholm Convention in China, the Inventory Group from the Research Center of Eco-Environmental Science of the Chinese Academy of Science (RCEES-CAS) compiled the emission inventory of unintentional produced POPs in China for the year 2004 from all known sources. The inventory is mainly based on the recommendations and methodology of the UNEP “Standardized Toolkit for Identification and Quantification of Dioxin and Furan Releases”. Most of the evaluations were made according to the default emission factors reported in the Toolkit. However, for the iron ore sintering process and EAF plants, default emission factors were integrated with monitoring data collected during the Sino-Italian U-POPs demonstration project. The total PCDDs/Fs release in China has been estimated in 9952.8 g I-TEQ with a total emission to air, to residues, to products and to water estimated at 4160.6, 5331.9, 384.1, and 76.2 g I-TEQ, respectively. Despite the large uncertainty in the emission factors, the metal sector was identified as a significant contributor to the national inventory from industrial sources. This follows worldwide experience where the metal sector is recognized as an important source of PCDDs/PCDFs. According to this inventory, most of the atmospheric emission of PCDDs/PCDFs originate during iron ore sintering (1150 g I-TEQ/a, accounting for 27.6 % of the national release to air), coke production (239.2 g I-TEQ) and steel production (123.5g I-TEQ, accounting for 5.7 % of the national release to air). Iron and steel production processes (628.1 g I-TEQ, 11.8 % of the national release to residues) and galvanized steel (863.6 g I-TEQ) are important sources of PCDD/PCDF releases in residues. The contribute of sinter plant to PCDD/PCDF releases associated with solid residues was marginal, only 0.69 g I-TEQ/a. The RCEES-CAS also developed the inventories of unintentional produced HCB (UP-HCB) and unintentional produced PCBs (UP-PCBs). Since there is no Toolkit developed by UNEP, the estimation of the inventory releases were mainly based on emission factors evaluated in Japan. The applicability to the Chinese conditions must be considered highly uncertain. The ferrous and non-ferrous metal production appears to be the most important source category in releasing unintentionally produced HCB and PCBs to the atmosphere. Iron ore sinter plants and iron and steel production plants are the most important sub-categories of this main source category in releasing unintentionally produced HCB and PCBs to the atmosphere. 3.1. Achievable emissions reduction from the iron and steel industry in China. The UNEP Toolkit typically considers different classes within each subcategory. Each class has a characteristic and different Emission Factor. Class 1 means processes/technologies with no or poor controls. Increasing the number of the class means processes/technologies with increased performance regarding PCDDs/PCDFs releases. The potential reduction of PCDDs/PCDFs releases for sinter plant and EAFs can be estimated by multiplying activity rates by the Emission Factors provided in the Toolkit for the highest class numbers, class 3, and corresponding to the highest technology plants, with full implementation of BAT and BEP. For sinter plants, class 3 Emission Factors reported in the Dioxin Toolkit are 0.3 µg TEQ/t-sinter and 0.003 µg TEQ/t-sinter to air and residues (dust), respectively, from sinter plant with “high technology emission reduction”. As far as EAFs are considered, Class 3 Emission Factors reported in the Dioxin Toolkit are 0.1 µg TEQ/t-

steel and 1.5 µg TEQ/t-steel to air and residues (filter dust), respectively, from “EAFs designed for low PCDD/PCDF emission” and feed with “clean scrap/virgin iron”. According to the emission factors reported in the UNEP Toolkit, in a BAT- and BEP-based scenario, PCDD/PCDF releases to air from sinter plants and EAFs could be 111 g I-TEQ/a, and 4.6 g I-TEQ/a, respectively. PCDD/PCDF releases to residues from EAFs could be reduced to 67.4 g ITEQ/a. The implementation of BAT and BEP to sinter plants and EAFs in China could provide a reduction of PCDD/PCDF releases of approximately 1720 g I-TEQ per year or about 90 % of the baseline scenario. It is recognized that default Emission Factors provided in the Toolkit represent average PCDDs/PCDFs emissions and that default Emission Factors, derived predominantly from measurements made in developed countries, might be not applicable to each country. Emission levels can vary considerably with technological processes, industrial practices, raw materials, and pollution control systems. Therefore, estimated values should be considered only as order of magnitude. 4. COMPARISON OF ESTIMATED EMISSIONS WITH MONITORING DATA FROM THE DEMONSTRATION ENTERPRISES. Under the Sino-Italian U-POPs project, two demonstration enterprises were selected, namely Shanghai Baosteel Group Corporation (BaoSteel) and Taiyuan Iron and Steel Company Ltd (TISCO). Two processes, the iron ore sintering process and the electric arc furnace steel-making process, considered to be relevant for PCDD/PCDF releases from the Iron and Steel industry, where investigated in both enterprises. Finally, two demonstration installations were selected for each process: • •

No. 1 iron ore sintering machine of BaoSteel and No. 3 sintering machine of TISCO; the 100-t EAF of BaoSteel Group Shanghai, No.5 Steel Co., Ltd. and the 50-t EAF of TISCO.

4.1 Inferences to the iron ore sintering process. No. 1 sintering machine of BaoSteel has an effective area of 450 m2. The designed annual production is 5,500,000 t. Feed contains 86.5 % imported ore and 13.5 % recycled materials. Recycled material contains pressed materials from the bottom of stock yard, dust from ESCS precipitators, slag sized iron, rolling mill scales, steel-making slag, and returned fine sinter. Additives added to the blend include quicklime, limestone, dolomite, and serpentine. Coke breeze and anthracite coal are added as solid fuels. Two fans draw process air through the entire length of the sinter bed into 23 wind-boxes located underneath the sinter strand. The main exhaust flow gas rate is 1,260,000 m3/h. Before discharging into the atmosphere, raw gases are treated in two threefields electrostatic precipitators (ESCS-A and ESCS-B). The waste gas (900,000 m3/h) at high temperature (290~300°C) from the discharge zone and the hot crusher is partially reused as combustion-supporting air for igniting furnace and for steam production. Waste gases (390,000 m3/h) from the annular cooler are treated separately in an electrostatic precipitator. The amount of dust separated by the off-gas treatment systems is 1.3 kg/t-sinter from the main exhaust, 5.6 kg/tsinter from the discharge zone and hot crusher and 5.3 kg/t-sinter from cooling and crushing. No. 3 sintering machine of TISCO has an effective area of 100 m2 and has been designed for an annual production of 1,186,000 t/a. Blended raw materials used for sintering contains 76% concentrated fine domestic ore, 6% concentrated fine imported ore and 18% recycled materials. Recycled materials contain returned fine sinter, red sludge from converters, coarse dust from blast furnaces and rolling mill scale. Additives added to the blend include lime and dolomite. Coke breeze and pulverized coal are added as solid fuels. Raw gases (540,000 m3/h) from the sinter strand, collected through the 15 wind-boxes located underneath the sinter strand, are treated in a single chamber, 3-fields ESP. Raw gases from the discharge zone are treated in a single chamber, 3fields ESP. Raw gases from the cooling and crushing zone (175,000 m3/h) are treated in a 3-fields ESP. The amount of dust separated by the off-gas treatment systems is 1.53 kg/t-sinter for the main ESP and 3.57 kg/t-sinter for the ESP at the discharge zone. In the baseline scenario, PCDD/PCDF atmospheric releases were generally low (less than 0.1 ng I-TEQ/Nm3) at No. 3 sintering machine of TISCO. Conversely, No. 1 sintering machine of

BaoSteel showed significant PCDD/PCDF releases to the atmosphere, in the range of 1.28-3.30 ng I-TEQ/Nm3. The proposed process modifications for No 1 sintering machine of BaoSteel were chosen according to the present knowledge of the mechanism formations of PCDDs/PCDFs in the iron ore sintering process: PCDDs/PCDFs formation is strongly related to the quality of raw materials. As a consequence, the demonstration plan was oriented towards a basic primary measure: raw materials selection. The implemented process modifications (avoiding processing electrostatic precipitator dust, avoiding processing of mill scale, and avoiding the addition of CaCl2 to the sinter feed) led to a reduction of PCDD/PCDF concentrations in the flue gases emitted into the atmosphere and in residues of approximately 50 %.

Estimated emission rates of PCDDs/PCDFs from No 1 sintering machine of Baosteel. Emission rate (g TEQ/a) Air Sinter dust Total Baseline scenario 15.12 4.07 19.19 Modified scenario 7.86 1.54 9.40

Since atmospheric PCDDs/PCDFs releases from No 3 sintering machine in TISCO were very low, it was very difficult to individuate a simple, viable, feasible and not excessively expensive opportunity to amend process procedures in order to further reduce an already low unintentional production of POPs. In the modified scenario, different feed compositions were tested in order to evaluate their effect on PCDD/PCDF releases. In particular, the relative proportion of domestic and imported iron ore was changed, different imported ore (from Australia and Brazil) were tested and some recycled materials were not added to the mixed feed. At No. 3 sintering machine of TISCO, PCDD/PCDF releases appeared not directly influenced by the tested feed composition. Probably, other factors rather than feed composition took control over the measured atmospheric emission values. However, values higher than 0.2 ng I-TEQ/Nm3 were observed during some trials.

Estimated emission rates of PCDDs/PCDFs from No 3 sintering machine of TISCO. Emission rate (g TEQ/a) Air ESP dust* Total Baseline scenario 0.10 0.37 0.47 st 1 modified scenario 0.36 0.26** 0.62 2nd modified scenario 0.40 0.66 3rd modified scenario 0.46 0.37 0.83 * Emission rates to residues have been calculated only for comparison. Since ESP dust is totally recycled, no release to the environment occurs through this route from No 3 sintering machine of TISCO. **(Calculated assuming 70:20:10 ratios for dust collected at 1st, 2nd, and 3rd fields) 4.2. Inferences to the electric arc furnace steel-making process. The 100-t EAF of BaoSteel Group Shanghai, No 5 Steel Corporation, Ltd. is a direct current (DC), one graphite electrode, with a nominal capacity of 100 tons and an operational capacity of 106 tons. The total annual production is 550,000 tons. Feed is 100% scrap. The furnace is enclosed in a doghouse. Primary off-gases are extracted from the 2nd hole. A canopy hood, located just above the EAF and the doghouse, collect secondary emissions from charging and tapping, as well as from EAF leakage during melting. The gaseous streams are treated in a common bag-house and emitted into the atmosphere through a common stack. Total waste gas

flow from the plant is about 0.85 million Nm3/h. The amount of abated dust is 15 kg/t-steel. The separated dust is recycled for zinc recovery and as a cement additive. The 50-t EAF of TISCO is an alternate current (AC), 3-phase graphite electrodes, with a nominal capacity of 50 tons and an operating capacity of 60 tons. The total annual production is 400,000 tons. The furnace is feed with liquid hot metal (35-41 tons, 58-60 % of nominal capacity) scrap (23-26 tons, 38-40% of nominal capacity), dust (4 tons) and pig iron (6 tons). Steel scrap is mainly composed of unsorted light scrap. Primary off gases, generated during the melting phase, are extracted from the 4th hole (70,000 Nm3/h) and sent to a post-combustion chamber for the full combustion of remaining CO and H2. A roof hood located just above the EAF captures secondary emissions, produced during charging and tapping of the furnace as well as from leakage during melting. Off gases captured by the hood are divided into two streams. Part of the off gases stream (approx. 1/5, max. 107,000 Nm3/h) is added to the waste gas collected by the 4th hole. This stream, composed by the primary off-gases (70,000 Nm3/h) and secondary off-gases (max. 107,000 Nm3/h) is sent to a bag-house for dust abatement. The main stream (approximately 350,000 Nm3/h) of raw gases captured by the canopy hood is sent to a dedicated bag-house for dust removal. Filter dust separated by APCDs is 25 kg/t steel. Collected dust is agglomerated and recycled into the EAF. In the baseline scenario, PCDD/PCDF atmospheric releases were generally low (less than 0.1 ng I-TEQ/Nm3) at both the 100-t EAF of BaoSteel and the 50-t EAF of TISCO. The proposed process modifications for the 100-t EAF of BaoSteel was chosen according to the present knowledge of the mechanism formations of PCDDs/PCDFs in the Iron & Steel production processes: PCDDs/PCDFs formation is strongly related to the quality of raw materials. As a consequence, the demonstration plan was oriented towards a basic primary measure: raw materials selection. The implemented process modification at the 100-t EAF of BaoSteel (improvement of scrap quality) effectively led to a reduction of PCDD/PCDF concentrations in the flue gases emitted into the atmosphere and in filter dust of approximately 50 %. Emission rates of PCDDs/PCDFs from the 100-t EAF of Baosteel. Emission rate (g TEQ/a) Air Filter dust Total Baseline scenario 0.33 5.06 5.39 Modified scenario 0.19 2.86 3.05

Emission data in the baseline scenario at the 50-t EAF of TISCO indicated that PCDD/PCDF releases were already very low and well below those from similar plants in Western Countries after the implementation of sophisticated and advanced technologies. Therefore, the modified scenarios were conceived in order to worsen the PCDDs/PCDFs releases and/or to test the effects of some process modifications (changing the relative percentages of steel scrap and liquid hot metal in feed) on PCDD/PCDF releases. The implemented process modification at the 50-t EAF of TISCO led to unpredictable results. Estimated emission rates of PCDDs/PCDFs from the 50-t EAF of TISCO. Emission rate (g TEQ/a) Air Filter dust* Total Baseline scenario 0.056 0.20 0.26 st 1 modified scenario 0.076 0.47 0.55 2nd modified scenario 0.57 0.39 0.96 * Emission rates to residues have been calculated only for comparison. Since filter dust is totally recycled, no release to the environment occurs through this route from the 50-t EAF of TISCO.

At the 50-t EAF of TISCO, PCDD/PCDF releases appeared not directly influenced by the tested feed composition. Probably, other factors rather than feed composition took control over the measured atmospheric emission value found during the sampling rounds. However, during the third

sampling round, values higher than 0.1 ng I-TEQ/Nm3 were observed. This is an important point if the objective is to achieve PCDD/PCDF emission concentrations less than 0.1 ng TEQ/Nm3 consistently.

5. COST EVALUATION FOR POSSIBLE TECHNICAL OPTIONS FOR REDUCING UPOPS RELEASES The steps involved in identifying and evaluating available technical options include: • • • • •

quantifying the emissions from the source; identifying technologies or techniques which could improve the level of abatement; quantifying the costs for implementing these abatement measures; estimating the effectiveness of these abatement measures at reducing emissions; combining cost and effectiveness data to provide a list of options ranked by cost per unit abated. Measures to control and abate emissions to air generally fall into two categories:

• •

primary or process-integrated measures that attempt to prevent or minimize the pollutant being formed and emitted from the main process; secondary or end-of pipe measures that attempt to destroy or recapture emissions after they have been formed and emitted from the main process.

Implementation of both primary and secondary measures is probably necessary to achieve the desired emission levels. 5.1. Reducing U-POPs releases from the iron ore sintering process. The following options for reducing U-POPs releases from No 1 sintering machine of BaoSteel and No 3 sintering machine of TISCO, mainly based on the experience with the iron ore sintering process in West Europe, were considered: • • • • • • •

raw material selection; re-circulation of off-gases; addition of suppressant (i.e. urea) high efficient dust removal equipment (fabric filters); adsorption onto activated carbon in combination with fabric filters; regenerative activated carbon technology; fine wet scrubbing system.

According to all available information, likely annualized costs, effectiveness and cost/effectiveness ratios were estimated for implementing each option at No 1 sintering machine of Baosteel and No 3 sintering machine of TISCO.

Estimated annualized incremental costs and cost/effectiveness ratios for proposed options at No 1 sintering machine of Baosteel. Technology option Annualized Cost/Effectiveness ratios incremental costs (MEUR/g TEQ reduced) (MEUR/a) Air Sinter Total dust Raw material selection 7.9 1.1 3.1 0.8 Urea addition 0.56 0.074 0.28 0.059 Recycling of off-gases 1.71 0.20 0.75 0.16

(Sectional waste gas recirculation). Recycling of off-gases (EOS) Fabric filter plus lignite injection Fine wet scrubbing system Fabric filter Regenerative activated carbon

2.25 13.14

0.23 1.35

0.85 -1.35

0.18 ∞

12.8 12.8 15.76

0.98 2.27 1.32

-0.98 -2.27 ∞

∞ ∞ 1.32

Estimated annualized incremental costs and cost/effectiveness ratios for proposed options at No. 3 sintering machine of TISCO. Technology option Annualized Cost/Effectiveness ratios incremental costs (MEUR/g TEQ reduced) (MEUR/a) Air Sinter Total dust Raw material selection 1.8 ∞ ∞ ∞ Urea addition 0.23 0.86 2.74 0.65 Recycling of off-gases (sectional 0.83 2.77 8.3 2.07 waste gas re-circulation). Recycling of off-gases (EOS) 0.95 2.72 8.64 2.07 Fabric filter 2.56 14.2 -14.2 ∞ Fabric filter plus lignite injection 2.78 9.27 -9.27 ∞ Fine wet scrubbing system 5.26 17.5 -17.5 ∞ Regenerative activated carbon 5.6 18.7 ∞ 18.7

Raw material selection, the option tested during the Sino-Italian U-POPs project, was able in reducing PCDD/PCDF releases only at No. 1 sintering machine of BaoSteel. Implementation costs of this option are high but costs and cost/effectiveness ratios are in the same order of magnitude of those for the implementation of advanced end-of-pipe technologies. Urea addition seems to be the most cost-effective option. Urea addition is attractive also because this technique, by suppressing PCDDs/PCDFs formation, not only reduces atmospheric emissions but also reduce PCDD/PCDF in sinter dust. However, it should be considered that literature data suggest a possible reduction of PCDDs/PCDFs of approximately 50 %. It can be estimated that a 50 % reduction in PCDD/PCDF emission at No 1 sintering machine of BaoSteel would still achieve an emission concentration higher than 1.0 ng TEQ/Nm3. The two options based on recycling part of the waste gas from the whole sinter strand back to the surface of the strand, both in the Emission Optimized Sintering (EOS) and the Sectional Waste Gas Re-circulation version, show similar cost/effectiveness ratios and annualized incremental costs. The reduction in emissions of particulate matter and particulate-related pollutants should be considered as an added benefit. However, since the reported reduction of PCDD/PCDF emission is approximately 55-70 %, it can be estimated that PCDD/PCDF emission at No 1 sintering machine of Baosteel would still achieve an emission concentration higher than 1.0 ng TEQ/Nm3 if this technique should be implemented. Fabric filters with lignite injection, fine wet scrubbing system, and regenerative activated carbon technology are the only options that can guarantee atmospheric PCDD/PCDF emissions less than 0.5 ng TEQ/Nm3. However, these emission concentrations can be achieved only with high annualized incremental costs (investment and operating) and high cost/effectiveness ratios. It is evident that fabric filters alone are less cost-effective of fabric filters with lignite injection. However, with fabric filters, with or without lignite injection, PCDDs/PCDFs are simply removed from the gaseous stream (adsorbed on fine particulate matter or on carbon particles) and not

destroyed. With the regenerative activated carbon technology, PCDD/PCDF adsorbed to the char are decomposed and destroyed during the regeneration process of the adsorbent bed. No 3 sintering machine of TISCO is characterized by low PCDD/PCDF emission values. Further reducing these values can be obtained only with excessively high unit abatement costs. The implementation of additional measures is probably not necessary at the moment since PCDD/PCDF releases are already low and comparable with those from similar plants in Western Countries after implementation of advanced technologies. The associated incremental cost for implementing and operating these technological options is, probably, an unnecessary additional cost. However, the following approach to the reduction of the unintentional production of POPs might be suggested for both No 1 sintering machine of Baosteel and No 3 sintering machine of TISCO: • • • • • • • •

implement a program for systematic measurements of PCDD/PCDF releases in atmospheric emissions and sinter dust; implement a continuous parameter monitoring systems coupled with the emission measurement program for the identification of those operating parameters or practices that may lead to reduced PCDD/PCDF emissions; identify and implement optimum operating parameters and practices that prevent or minimize the formation of PCDDs/PCDFs in the sintering process; identify and avoid substances in the sinter feed mix that contribute to the formation of PCDDs/PCDFs in the sintering process; investigate the addition of materials such as urea that may suppress or prevent the formation and release of PCDDs/PCDFs in the sintering process; evaluate the possibility of recycling part of the waste gas from the whole sinter strand back to the surface of the strand; evaluate the possibility of implementing one of the following technologies: fabric filter with lignite injection, fine wet scrubbing system, regenerative activated carbon technology; identify and implement best environmental practices for the storage, handling, and disposal of material containing PCDDs/PCDFs such as sinter dust.

5.2. Reducing U-POPs releases from the electric arc furnace steel-making process. The following options for reducing U-POPs releases from the 100-t EAF of BaoSteel and the 50-t EAF of TISCO, mainly based on the experience with the EAF steel-making process in West Europe, were considered: • • • •

raw material selection; adsorption onto activated carbon in combination with fabric filters; post-combustion and quenching of off-gases; change to a joined off-gas ducting system (only for the 50-t EAF of TISCO).

According to all available information, likely annualized costs, effectiveness and cost/effectiveness ratios were estimated for implementing each option at both the 100-t EAF of BaoSteel and the 50-t EAF of TISCO.

Estimated annualized incremental costs and cost/effectiveness ratios for the proposed options at the 100-t EAF of Basoteel. Technology option Annualized incremental Cost/Effectveness ratios cost (MEUR/g TEQ reduced) (MEUR/a) Air Filter Total dust Raw material selection 5.2 37 2.4 2.2

Lignite injection post-combustion and quenching

0.27 0.33

0.97 1.99

-0.97 0.13

∞ 0.12

Estimated annualized incremental costs and cost/effectiveness ratios for the proposed options at the 50-t EAF of TISCO. Cost/Effectiveness ratios Technology option Annualized incremental (MEUR/g TEQ reduced) costs (MEUR/a) Air Filter Total dust Raw material selection 1.5 ∞ ∞ ∞ Change to a joined off-gases 0.11 0.59 -0.59 ∞ ducting system Lignite injection 0.32 1.62 -1.62 ∞ Post-combustion and quenching 0.33 5.46 1.02 0.86

Raw material selection, the option selected during the demonstration plan, was able in reducing PCDD/PCDF releases both to the air and to filter dust only at the 100-t EAF of BaoSteel. The reduction was approximately 50%. However, the cost of implementing this option and the cost/effectiveness ratios appear to be excessively high. This option seems to be the least cost/effective. The annualized incremental costs for lignite injection and post-combustion/quenching of the raw gases seems to be similar for both options and for both installations. The cost/effectiveness ratios (to air) appear to be quite high for both options, in the order of millions EUR per g TEQ reduced. Both options seem to be not cost-effective in reducing PCDD/PCDF atmospheric emissions from both installations. The main reason of the high values of the cost/effectiveness ratios must be found in the low values of PCDD/PCDF atmospheric releases in the baseline scenario. A substantial difference between the two options is that with lignite injection to supplement the fabric filter bag-house technology PCDDs/PCDFs are simply removed from the gaseous stream (adsorbed on the carbon particles) and not destroyed. On the other hand, post-combustion can be considered capable to destroy completely PCDDs/PCDFs in primary off-gases. The following rapid quenching should avoid de novo synthesis in raw gases. Therefore, a reduction in the total releases from the plant should be attained. Changing the actual layout of ducting and de-dusting system of raw gases from a separate system to a joined system seems the most cost/effective option for reducing PCDD/PCDF atmospheric releases from the 50-t EAF of TISCO. The cost/effectiveness ratio for this option seems, however, still high. The main reason of the high value of the cost/effectiveness ratio must be found in the low values of the present PCDD/PCDF atmospheric releases from the plant. With low PCDD/PCDF atmospheric releases both from the 100-t EAF of BaoSteel and the 50-t EAF of TISCO the implementation of BAT/BEP is not a priority. The incremental cost for implementing and operating these techniques is, probably, an unnecessary additional cost. However, if the aim is to achieve PCDD/PCDF emission concentrations of less than 0.1 ng TEQ/Nm3 consistently, the following approach to the reduction in the unintentional production of POPs might be suggested for both the 100-t EAF of Baosteel Group Shanghai, No. 5 Steel Co., Ltd. and the 50-t EAF of TISCO: • • •

implement a program for systematic measurements of PCDD/PCDF releases in atmospheric emissions and filter dust; implement a continuous parameter monitoring system coupled with the emission measurement program for the identification of those operating parameters or practices that may lead to reduced PCDD/PCDF emissions; identify and implement optimum operating parameters and practices that prevent or minimize the formation of PCDDs/PCDFs in the steel-making process;

• • • • • •

identify and avoid substances in the feed mix that contribute to the formation of PCDDs/PCDFs in the steel-making process; evaluate the possibility of changing the actual layout of ducting and de-dusting of raw gases from a separate system to a joined ducting system (only for the 50-t EAF of TISCO); evaluate the possibility of avoiding the recycle of filter dust (only for the 50-t EAF of TISCO); evaluate the possibility of implementing lignite injection to supplement the fabric filter baghouse technology; evaluate the possibility of implementing post-combustion and quenching to the raw primary offgases; identify and implement best environmental practices for the storage, handling, and disposal of material containing PCDDs/PCDFs such as filter dust.

6. POSSIBLE TECHNICAL OPTIONS AND NATION-WIDE COSTS FOR THE U-POPS REDUCTION STRATEGY IN CHINA Likely annualized costs, effectiveness and cost/effectiveness ratios were estimated for implementing each option at all sinter plants and all EAF steel-making plants across China. The evaluation of the cost-effectiveness of the proposed technical options for reducing PCDD/PCDF releases from the Iron & Steel Industry in China have been performed considering the 2004 as the baseline scenario since the available releases inventory of PCDDs/PCDFs in China is for the base year 2004. Moreover, two different baseline scenarios have been considered. The first baseline scenario has been set according to the actual number and distribution of sintering machines and EAFs in China. The second baseline scenario has been set under the hypothesis of closure of small plants and their replacement with larger ones. Some of the technology options available for PCDDs/PCDFs reduction are not suitable for implementation on small plants. Small plants does not allow for possible economies of scale and this might exclude the affordability of the technique in comparison with the market price for the goods produced. In addition, the ‘‘China Iron and Steel industry development policy’ sets new technology development guidelines and new requirements for steel-makers in China, including the increase of the scale of production. Under this alternative baseline scenario, the likely range of incremental cost might be approximately 20 % lower as a consequence of economies of scale.

Summary of costs, abatement potential and cost-effectiveness ratios for different technology options applied to the iron ore sintering process. Baseline 1: all existing sinter plants. Remaining emission Cost/effectiveness ratios Technology option Total Total Total (g TEQ/a) (MEUR/g TEQ reduced) investment operating annualized cost across cost across cost across Air Residues Total Air Residues Total China China China (MEUR) (MEUR/a) (MEUR/a) Baseline 1150 0.7 1150.7 Raw material selection 0 665 665 862.5 114 976.5 2.3 - 5.9 3.8 Emission Optimized 3600 -180 406 402.5 0.25 402.7 0.54 902 0.54 sintering (EOS) Sectional waste gas re2585 0 421 506 0.3 506.3 0.65 1052 0.65 circulation Urea addition 277÷553 23÷34 68÷124 575 0.35 575.35 0.12÷0.22 194÷354 0.12÷0.22 Fabric filters 958÷2844 337÷2461 493÷2924 667 483.7 1150.7 1÷6 - (1÷6) ∞ Fabric filter plus lignite 1038÷2924 341÷2465 510÷2932 490 660.7 1150.7 0.8÷4.4 - (0.8÷4.4) ∞ injection Regenerative activated 8430 430 1802 328 0.7 328.7 2.2 ∞ 2.2 carbon (RAC) technology Fine wet scrubbing 7118÷15246 57 1215÷2538 490 660.7 1150.7 1.8÷3.8 - (1.8÷3.8) ∞ system

Summary of costs, abatement potential and cost-effectiveness ratios for different technology options applied to the iron ore sintering process. Baseline 2: small sinter plants closed and substituted with larger plants. Remaining emission Cost/effectiveness ratios Technology option Total Total Total (g TEQ/a) (MEUR/g TEQ reduced) investment operating annualized cost across cost across cost across Air Residues Total Air Residues Total China China China (MEUR) (MEUR/a) (MEUR/a) Baseline 1150 0.7 1150.7 Emission Optimized sintering (EOS) Sectional waste gas recirculation. Urea addition Regenerative activated carbon technology Fine wet scrubbing system

2900

-145

327

402.5

0.25

402.7

0.44

727

0.44

2084

0

339

506

0.3

506.3

0.53

848

0.53

145÷290 6794

23÷34 430

46÷81 1536

575 328

0.35 0.7

575.35 328.7

0.08÷0.14 1.87

133÷232 ∞

0.08÷0.14 1.87

5730÷12317

57

989÷2061

490

660.7

1150.7

1.5÷3.1

-(1.5÷3.1)

∞

Summary of costs, abatement potential and cost-effectiveness ratios for different technology options applied to the EAF steel-making process. Baseline 1: all existing EAFs. Remaining emission Cost/effectiveness ratios Technology option Total Total Total (g TEQ/a) (MEUR/g TEQ reduced) investment operating annualized cost across cost across cost across Air Residues Total Air Residues Total China China China (MEUR) (MEUR/a) (MEUR/a) Baseline 123.5 628.1 751.6 Raw material selection 0 365 365 74.1 376.9 451 7.4 1.45 1.2 Change to a joined 26÷79 1.9 6.1÷14.7 74.1 677.5 751.6 0.12÷0.30 ∞ ducting and cleaning (0.12÷0.30) system Lignite injection 21.4 11.2 14.7 61.7 689.8 751.6 0.24 -0.24 ∞ Post-combustion and 83 4.5 18 61.7 314.1 375.8 0.30 0.06 0.05 quenching

Summary of costs, abatement potential and cost-effectiveness ratios for different technology options applied to the EAF steel-making process. Baseline 2: small EAFs closed and substituted with larger plants. Technology option

Baseline Lignite injection Post-combustion and quenching

Total investment cost across China (MEUR) 15.6 62

Total operating cost across China (MEUR/a) 11.2 4.5

Total annualized cost across China (MEUR/a) 13.7 14.6

Remaining emission (g TEQ/a) Air Residues Total

123.5 61.75 61.75

628.1 689.85 314.05

751.6 751.6 375.8

Cost/effectiveness ratios (MEUR/g TEQ reduced) Air Residues Total

0.22 0.24

- 0.22 0.05

∞ 0.04

The possibility of implementation of the presented options should be carried out on a sitespecific basis to take into consideration site-specific requirements, site-specific space considerations, operating conditions, and economic situation. Implementation of at least one or more of the identified options should be technically feasible for all plants. However, some of the options require further investigation before they can be implemented and some may not be applicable to all plants. Some of the options would unlikely be taken forward solely on the grounds of reductions in PCDD/PCDF emissions. Measures to reduce PCDD/PCDF emissions may also reduce emissions, and thus impacts, of other toxic pollutants, or have other benefits, which may mean that the costs attributable to PCDDs/PCDFs are reduced. A wide variety of input materials, different modes of operations and a wide range of efficiencies of air pollution control systems characterize the iron ore sintering and the EAF steel-making processes. As a consequence, PCDD/PCDF emissions can be expected to vary widely from plant to plant and, for an individual plant, they can also change over time. Up to now, very few data are available regarding U-POPs releases from the Iron and Steel Industry in China. The available baseline emission is mainly based on the recommendations and methodology of the UNEP “Dioxin Toolkit”. The methodology provided in the Toolkit is a very transparent tool for estimating releases and may be usefully employed to meet inventory obligations under the Stockholm Convention. Of course, its applicability needs to be verified with direct measurements of representative samples taken from actual industrial sources. A reliable evaluation of existing PCDD/PCDF releases to the environment would help in deciding what might be the best way for reducing releases and would be an aid in determining priorities in the selection of specific technology options. Any emission reduction strategy should start with first implementing the most cost-effective measures. Reduction of PCDD/PCDF emissions from manufacturing processes in the Iron and Steel Industry is a complex problem, not simply resolvable with implementing some technology options, but it also involves control of the process and combustion parameters. Given the complexity of the problem, the range of available control options and the very large number of potential significant sources, the most effective approach for reducing PCDD/PCDF releases from the Iron and Steel Industry in China should be the evaluation of the most cost-effective combination of primary and secondary measures on a case-by-case basis. Reduction of emissions of U-POPs requires that the technical solution that produce minimum emissions (BAT/BEP) should be chosen taking into account the balance between the costs incurred by the operators and the society as a whole and environmental benefits. However, while approaching the problem on an individual site basis, the national and global significance of PCDD/PCDF releases should be always kept in mind. Keeping in mind the limitations due to the uncertainties of available information, the following approach, based on the findings identified under the Sino-Italian U-POPs project, could be suggested as consideration for the development of an U-POPs reduction strategy from the Iron and Steel Industry in China: • •

• •

implement a program for systematic measurements of PCDD/PCDF releases in atmospheric emissions and filter dust. A reasonable number of facilities should be included in the testing program, including small and small-to-medium facilities; implement a continuous parameter monitoring systems coupled with the emission measurement program for the identification of those operating parameters or practices that may lead to reduced PCDD/PCDF emissions. The information to be collected could include raw materials used, operating conditions and parameters, and off-gas data at key points in the gas conditioning system; identify and implement optimum operating parameters and practices that prevent or minimize the formation of PCDDs/PCDFs; identify and avoid substances in the feed mix that contribute to the formation of PCDDs/PCDFs;

• •

evaluate the possibility of implementing secondary (end-of-pipe) measures at those facilities with elevated PCDD/PCDF releases; identify and implement best environmental practices for the storage, handling, and disposal of material containing PCDDs/PCDFs such as filter dust. To assist with the above, the following recommendations can be indicated:

• •

•

the closure of small and out-to-date installations and the construction of new plants with a larger capacity should be completed as quick as possible; a detailed survey should be performed with the aim of gathering data for a better characterization of the industry sector in terms of raw materials, types of processes, size/capacity of processes, relevant process details, geographical distribution, air pollution control systems, emission factors, etc. An insight in emission data under individual specific technological processes and in the efficiency of the air pollution control devices is necessary; the sharing of information that would assist enterprises in identifying pollution prevention practices and in assessing the abatement efficiency of techniques as well as details on capital and operating costs should be encouraged, particularly between facilities which will be able to achieve significant emission reductions and those still facing with elevated PCDD/PCDF emissions.

Appendix A -Profile of the Industrial Sector in China-

400

349,4 350

300

280,5

250 222,33 200

182,25 151,63

150

100

80,93

71

65,35

89,54

92,61

95,36

1993

1994

1995

101,24

108,91

114,59

123,95 128,5

50

0 1990

1991

1992

1996

1997

1998

1999

2000

2001

2002

2003

2004

2005

Year

Crude steel output in China from 1990 to 2005 (million tons).

100 Open-hearth

BOF

EAF

90

80

82,8

83,3

83,5

83,3

82,4

15,7

15,9

15,9

16,7

17,6

85,1

87,4

79,5 73,5

70 67,3

68,8

63,8 60

58,5

60,5

60,9

21,1 18,4

17,3

60,7

50

40

30

20

21,4 20,1

21,8

23,2 16,1

21,2 15

19

18,7

13,7

12,5

10

17,6

15,8

14,9

12,6

8,9 4,7 1,5

0 1990

1991

1992

1993

1994

1995

1996

1997

1998

1999

0,8 2000

0,6 2001

0

0

0

0

2002

2003

2004

2005

Year

Production of crude steel in open-hearth furnaces, electric furnaces and oxygen converters (%).

120

100 93,03

93,5

94

2002

2003

2004

95,7

89,68 84,81 78,62

80 71,11 63,78 60

55,91 49,37 41,75

40

36,11 31,79 25,07

27,71

20

0 1990

1991

1992

1993

1994

1995

1996

1997

1998

1999

2000

2001

2005

Year

Continuously-cast steel output in China from 1990 to 2005 (%).

1,2

1

0,997

0,996 0,964

0,976

0,958

0,973

0,959

0,938 0,901 0,833 0,781

0,8

0,747 0,715

0,6

0,4

0,2

0 1990

1991

1992

1993

1994

1995

1996

1997

1998

1999

2000

2001

2002

Year

Energy consumption of Chinese steel mills from 1990 to 2002 (tce/t-steel).

140 124 118

120 110 99

100 83,6 80 72 61,3 60 50,8

51,1

50,5

1990

1991

1992

58,5

53,7

40

20

0 1993

1994

1995

1996

1997

1998

1999

2000

2001

Year

Average PCI ratio of China’s major steel plants from 1990 to 2001 (kg/t).

70

59

60 53 50

47

40 36

30

33

33

1998

1999

27 24 19

20 16

20

20

1994

1995

17

14 10

0 1990

1991

1992

1993

1996

1997

2000

2001

2002

2003

Year

Chinese steel mills with an annual output of over 1 million tons from 1990 to 2003.

50 44,95 45 41,67 39,06

40

35 30,49 30

24

25 20,75 20

15

19,66 18,11

17,63 14,02

18,93

19,12

1996

1997

19,49

20,2

18,14

15

10

5

0 1990

1991

1992

1993

1994

1995

1998

1999

2000

2001

2002

2003

2004

2005

Year

Production of crude steel in electric furnaces in China. From 1990 to 2005 (million tons)

16 14,6 14

12 10,22 9,78

10

9,23 7,82

8

6 5,1

4

3,34

3,18 2,12

2

1,34

1,5

1991

1992

2,02 1,35

1,28

1,2

1995

1996

1997

0 1993

1994

1998

1999

2000

2001

2002

2003

Year

Imported steel scrap in China from 1991 to 2005 (million tons).

2004

2005

Production in China’s iron and steel industry in the year 2005. Product Production (million tons) Iron ore (Fe 28 %)* 335.6 Coke* 224 Normal sinter ore 51.7 High-basicity sinter ore 317.5 Pelletized iron ore 59.1 Pig iron 330.4 Direct reduced iron 0.5 Crude steel 349.4 Crude steel by process BOF 304.4 EAF 44.95 Ingots Continuously-cast steel Liquid steel for casting

14.1 334.3 1.0

* 2004

Main indexes of the Chinese steel industry in 1990 and 2002. 1990 Yield of steel product, % 83.1 Energy consumption, tce/t-steel 0.997 Utilization rate of BF, t/m3·d 1.73 Coke ratio, kg/t 557 PCI ratio, kg/t 50.8 Converter campaign, heats 438 Continuous casting ratio, % 25.07

National consumption of steel in China in 2005. Apparent consumption of crude steel Apparent consumption of crude steel per capita Apparent consumption of finished steel Apparent consumption of finished steel per capita Scrap consumption* * 2004

Year 2005 export/import (Unit: million tons). Product name Iron ore Scrap Pig iron Steel Semi-finished and finished steel products

2002 94.2 0.715 2.448 415 125 4268 93.03

350.17 million tons 268.6 kg 327.00 million tons 250.8 kg 51.0 million tons

Export 0 0 2.24 20.1 27.41

Import 275.26 10.14 0.27 33.2 27.31

Top steel-producing company in China in 2005 Company Production Million tons per year Shanghai Baosteel Group Corporation 22.7 Tangshan Steel Corporation 16.1 Wuhan Iron and Steel Corporation 13.0 Anshan Iron and Steel Group Corporation 11.9 Jiangsu Shagang 10.5 Shougang 10.4 Jinan 10.4 Laiwu 10.3 Ma'anshan Iron and Steel Corporation 9.6 Handan 7.3 Baotou Iron and Steel Corporation 7.0 Benxi Iron and Steel Group 6.5 Panzhihua Steel Company 6.2 Anyang Iron and Steel Group Company 5.8 Jiuquan Iron & Steel (Group) Company 5.7 Taiyuan Iron & Steel (Group) Company 5.4 Jianlong Iron & Steel Group 5.0 Liuzhou Iron & Steel Company 4.6 Beitei Iron & Steel Group Company 4.6 Tangshan Guofeng 4.5 Nangang 4.4 Jiangxi Xinyu Iron & Steel Company 4.0 Xuanhua Steel 3.6 Shaoguan Iron and Steel Group Company 3.5 Kunming Iron and Steel Company 3.5 Tianjin Tiantie 3.4 Hebei Jinxi Iron & Steel Company 3.4 Pingxiang Iron and Steel Company 3.4

Rank in the World 6 12 18 19 21 22 23 24 26 33 35 38 40 44 45 48 51 52 53 54 58 63 68 69 70 72 75 76

45.5%

140

129,52 120

100

80 21.1% 60,01

18.2%

60 51,68

40

9.0% 25,63

5.9% 16,7

20

0.4% 9

33

48

260

75

300-999 m3

101-299 m3

0 > 3000 m3

2000-2999 m3

1000-1999 m3

1,03

12

< 100 m3

Capacity

Distribution of blast furnaces in China in 2005 (million tons).

Classification of sinter plants in China in 2005. Class Total number 2 (m ) ≤18 4 19-35 104 36-89 119 90-129 63 ≥130 79 Total 369

Classification of EAFs in China in 2005. Class Total Designed (t) number capacity (Mt/a) ≤ 10 t 39 1.02 11 – 49 t 76 10.77 50 – 99 t 32 15.97 ≥ 100 t 12 11.06 Total 159 38.82

Total capacity (Mt/a) 0.94 40.34 80.69 69.61 187.86 379.44

total Average capacity (Mt/a) 0.026 0.14 0.50 0.92 0.24

Share of the total (%) 0.3 10.6 21.3 18.3 49.5 100

Share of total (%) 2.6 27.7 41.1 28.5 100

Eastern Region, 60.89 % Central Region 25.55 % Western Region, 13.56 %

Chinese steel output in 2002 by regions

Distribution (in % of the output) of Chinese steel production from 1950 to 2002. 1950 1970 1980 1990 2000 2002 North China 12.72 19.96 21.51 22.69 25.82 28.89 Northeast China 82.83 37.32 26.44 20.89 14.16 12.65 East China 1.95 23.7 24.74 27.57 31.91 31.42 Central South China 0.90 13.57 15.05 16.64 15.75 16.32 Southwest China 1.61 4.51 10.34 9.38 8.93 7.81 Northwest China 0 0.94 1.91 2.82 3.43 2.91

APPENDIX B -BaoSteel and TISCO sinter plant & EAF data-

No 1 sintering machine of BaoSteel

Operational data. In operation since Width of the sinter strand (m) Length of the sinter stand (m) Effective area (m2) Bed height (mm) Speed of the sinter strand (m/min) Annual production (t) Productivity (t/h) Wind-boxes (n°) Operating rate (%) Operational time (h/a) Raw materials

Additional fuels Off gas cleaning systems

Heat recovery

1985 5.5 90 495 650 - 720 2.0 – 2.8 5,500,000 650 23 96.5 8453 Imported ores, inner recycled materials, quicklime, limestone, dolomite, serpentine, coke breeze, anthracite coal COG (used for ignition) ESCS (main exhaust); EP (charge end and discharge end); multi-tube dust cleaner (high temperature waste gas) The waste gas with high temperature (290~300°C) is reused as combustionsupporting air for igniting furnace and holding furnace. Steam production (68.2 kg/t-sinter).

Dust

Air

Average concentrations of PCDD/PCDF (ng I-TEQ/Nm3 or ng I-TEQ/kg dust). Sample Baseline scenario Modified scenario 3 ESCS-A 1.28* ng I-TEQ/Nm 1.54 ng I-TEQ/Nm3 ESCS-B 3.30 ng I-TEQ/Nm3 1.15 ng I-TEQ/Nm3 3 ESP 0.24 ng I-TEQ/Nm ESCSs 267 ng I-TEQ/kg 336 ng I-TEQ/kg (1st and 2nd fields) ESCSs 2551 ng I-TEQ/kg 1186 ng I-TEQ/kg rd (3 field) ESP dust 46 ng I-TEQ/kg 25 ng I-TEQ/kg *Only one of the two available analytical results, 1.28 ng I-TEQ/Nm3, was considered since the other, 0.006 ng I-TEQ/Nm3, appears excessively low and unreal.

Dust

Air

Estimated emission factors of PCDD/PCDF (µg I-TEQ/t sinter). Baseline scenario Modified scenario ESCSs main stack 2.75 1.43 ESP 0.03 ESCSs 0.39* 0.37* (1st and 2nd fields) ESCSs 0.74 0.28 (3rd field) ESP dust 0.35* 0.12* * Emission Factors to residues from the front container and ESP have been calculated only for comparison. Since these residues are totally recycled, no release to the environment occurs through this route from No 1 sintering machine of Baosteel.

No 3 sintering machine of TISCO.

Operational data In operation since Width of the sinter strand (m) Length of the sinter stand (m) Effective area (m2) Bed height (mm) Speed of the sinter strand (m/min) Annual production (t) Productivity (t/h) Wind-boxes (n°) Operating rate (%) Operational time (h/a) Raw materials

Additional fuels Off gas cleaning systems Heat recovery

1996 2.5 40 100 700 1.01 1,186,000 142.1 15 95.3 8345 Domestic ore, imported ore, inner recycled materials, lime, dolomite, coke breeze, pulverized coal COG (used for ignition) ESPs (main exhaust, discharge zone, cooling and crushing) None

Average concentrations of PCDDs/PCDFs (ng I-TEQ/Nm3 or ng I-TEQ/kg dust) Average concentration in Average concentration in cleaned gases ESP dust Air ESP dust Baseline scenario 0.036 204 st 1 modified scenario 0.23 145* 2nd modified scenario 0.27 3rd modified scenario 0.23 190 *(Calculated assuming 70:20:10 ratios for dust collected at 1st, 2nd, and 3rd fields)

Emission factors of PCDD/PCDF (µg I-TEQ/t sinter). Emission Factor to air

Emission Factor to ESP dust* ESP dust 0.31 0.22**

Air Baseline scenario 0.086 1st modified scenario 0.30 nd 2 modified scenario 0.34 3rd modified scenario 0.39 0.31 * Emission Factors to residues (ESP dust) have been calculated only for comparison. Since ESP dust is totally recycled, no release to the environment occurs through this route from No 3 sintering machine of TISCO. **(Calculated assuming 70:20:10 ratios for dust collected at 1st, 2nd, and 3rd fields)

100-t EAF of Baosteel Group Shanghai, No.5 Steel Co., Ltd.

Operational data In operation since Furnace type Number of graphite electrodes Produced steel grade Nominal capacity (t) Batch capacity (t) Metallic charge weight, t Raw materials Productivity, t/hour Capacity (t/a) Operational time (d/a) Additional fuels Additional burners

1997 DC, UHP one Carbon steel, low alloyed steel, highalloyed steel 100 106 120.8 Scrap 84.8 550,000 323 Coal, gas Six (one oxygen lance and five sidewall oxy-fuel burners) None

Nitrogen, argon or other inert gases injection in the bottom of the EAF Duration of the cycle (tap to tap) 75 Cooling system Water cooled side walls, water cooled ducts, air-cooled heat exchanger Tapping system EBT Emission collection Direct extraction (2nd hole), dog-house, roof hood Off gas cleaning system Fabric filter Heat recovery None Secondary metallurgy Ladle furnace, vacuum degassing

Average PCDD/PCDF concentrations Emission to air, ng I-TEQ/Nm3 Filter dust, ng I-TEQ/kg dust

Baseline scenario 0.079 610

Emission Factors (µg I-TEQ/t-steel) of PCDD/PCDF Baseline scenario Emission Factor to air 0.60 Emission Factor to residues 9.2

Modified scenario 0.041 350

Modified scenario 0.35 5.2

50-t EAF of TISCO.

Operational data In operation since Furnace type Number of graphite electrodes Produced steel grade Nominal capacity (t) Batch capacity (t) Metallic charge weight, t/furnace Raw materials

2000 AC, UHP Three Several 50 60 63.5 Liquid hot metal, scrap, pig iron, filter dust, recycled materials. Productivity, t/hour 57 Capacity (t/a) 400,000 Operational time (h/a) 6967 Additional fuels Coal Additional burners One water-cooled oxygen lance at furnace door (4000 m3/h) and two sidewall lances (400 m3/h each, only oxygen injection). Nitrogen, argon or other inert gases None injection in the bottom of the EAF Duration of the cycle tap to tap, min. 63 Cooling system Water cooled side walls, water cooled ducts, air-cooled heat exchanger Tapping system EBT Emission collection Direct extraction (4th hole), roof hood. Off gas cleaning system Fabric filter Heat recovery None Secondary metallurgy Ladle metallurgy, vacuum degassing

Average PCDD/PCDF concentrations

Bag-house primary emission (4th hole) Bag-house secondary emission (hood)

Emission to air, ng I-TEQ/Nm3 Emission to dust, ng I-TEQ/kg dust Emission to air, ng I-TEQ/Nm3 Emission to dust, ng I-TEQ/kg dust

Baseline scenario 0.005

1st modified scenario 0.020

2nd modified scenario 0.13

26

63

55

0.010

0.016

0.17

6.9

12

7.5

Emission Factors (µg I-TEQ/t-steel) of PCDDs/PCDFs Baseline 1st modified 2nd modified scenario scenario scenario Emission Factor to air 0.14 0.19 1.43 Emission Factor to residues* 0.51 1.17 0.98 * Emission Factors to residues have been calculated only for comparison. Since filter dust is totally recycled, no release to the environment occurs through this route from the 50-t EAF of TISCO.

APPENDIX C -Cost/effectiveness analysis-

An evaluation of the costs needed to implement BAT/BEP in the Iron and Steel sector in China can be based on the cost/effectiveness evaluation performed in the framework of the Sino-Italian UP-POP project. Incremental costs were expressed by two variables, an initial capital investment, and annual operating and maintenance costs. The calculations have been carried out as follows; firstly the incremental costs (capital and operating costs) and the effectiveness (the decrement in the amount emitted in a standard time period, i.e. g TEQ reduced per year) were calculated, and secondly, the cost/effectiveness ratios (the ratio of cost to effectiveness, i.e. in units of EUR per g TEQ not emitted into the environment) for the optimized process, both for the PCDD/PCDF emission to air and to solid residues were obtained. The methodology adopted for the calculation of the cost/effectiveness consists in calculating the annualized cost by using the following relationship: Annualized cost (EUR/a) = (Investment cost (EUR) * Annualization factor) + Operating costs (EUR/a)

The annualization factor (e) is given by:

  d e= +d n  (1 + d ) − 1 where d is the discount (interest) rate and n is the amortization period in years. To reflect the effect of timing on the present value of costs, a discount rate of 10 % has been used. A 10-year amortization period has been assumed for all technology options by assuming that a technology option would last at least 10 years. Thus, the annualization factor will assume the value of 0.163 in all of the evaluations. Investment and operating costs have been derived from available literature data for reference plants. In order to take into account different sizes, the average cost for retrofitting an existing plant has been calculated by using the scale exponent method to scale the cost of the reference plant to the actual size of the plant. An approximate cost value has been calculated according to the formula: Cx = Cref * (scalex/scaleref)e where: Cx = cost of plant x; Cref = cost of the reference plant; scalex = scale of the plant x (i.e., the plant capacity, the waste gas flow, etc.); scaleref = scale of the reference plant (i.e., the plant capacity, the waste gas flow, etc.); e = approximation factor. By assuming a value of the exponent e of 0.6 (as usually done), the estimated investment cost for retrofitting an existing plant can be calculated. Effectiveness for each proposed option have been derived from available literature data for reference plants and under various assumptions based on expert judgment of these available data.

It should be underlined that there is a great deal of uncertainty in selecting specific scenarios for estimating costs and effectiveness. The most important uncertainties in costs estimates are: • • • • • •

only limited information regarding the costs of implementing BAT/BEP for reducing U-POPs releases is publicly available and a clear year of reference for costs of specific measures is often not given; the available cost information represents costs based on specific cases for a particular installation and it is not simple to translate and adapt this information to different plants of the industry sector; available information for a specific case may not be directly applicable to other sites because local conditions, site-specific influences and corporate specific components generate complex effects on costs; additional uncertainty is introduced when scaling up costs from a specific case to the sector as a whole; specific technology options for emission reduction of U-POPs (generally PCDDs/PCDFs) may also reduce emissions of other substances as well (e.g. PAHs, mercury, particulate matter, heavy metals) and co-benefits of the measures are not accounted for in the costs; it is likely that costs will be lower if technology options will be built into a new system rather than retrofitted to an existing system.

However, the largest uncertainty is the expected performance of the technical options since there is very little published information on dioxin destruction or removal efficiencies. The following limitations exist in available information: • • • •

•

site-specific technical details and operating parameters are generally not available for those plants which successfully reached low emission values; operating practices and environmental control systems vary from plant to plant and, consequently, the effectiveness of PCDDs/PCDFs emission control can vary from plant to plant; reported emissions vary widely and consequently the effectiveness of the various technical options is uncertain; limited information on the absolute effectiveness in PCDDs/PCDFs reduction is available. Often, this information is based on claims from equipment suppliers; equipment suppliers do not generally guarantee performance below 0.1 TEQ ng/Nm3 since emission standards are 0.1 ng TEQ/Nm3. most of the available data are in the form of a concentration or an emission factor (ng TEQ/Nm3 or µg/t). It is not a simple task to translate this information into dioxin removal rates.

Without more information it is not easy to correlate the operating parameters and the proposed options with PCDDs/PCDFs reduction. While the most commonly used BAT/BEP are easily identified, the assessment of BAT/BEP implementation feasibility and the estimate of PCDDs/PCDFs reduction effectiveness are limited by the above information limitations. The information collected in the framework of the Sino-Italian U-POPs project only gives an order of magnitude of costs and effectiveness and allows only a limited comparison between techniques. Moreover they are generally based on prices in Western Europe and do not include the adjustments to local conditions. Therefore, the information should be considered only as a rough estimate and subject to a high degree of uncertainty. Moreover, various assumptions based on expert judgment of available data are necessary in order to model the expected performance of technical options and the order of magnitude of likely cost values. More problems that are encountered in the evaluation of the cost/effectiveness of possible technology options suitable for the reduction of PCDDs/PCDFs from the Chinese Iron & Steel Industry are:

•

•

• •

unintentional releases of PCDDs/PCDFs in China from the iron and steel industry have been estimated in the framework of the activities related to the implementation of the Stockholm Convention. However, due to the uncertainty in literature emission factors, these estimates have to be considered only as a first approximation. Up to now, the few available data regarding UPOPs releases from the iron and steel industry in China has been collected in the framework of the Sino-Italian UP-POPs Project; extensive information on the iron and steel industry in the People’s Republic of China is not yet available, due to the very high number of enterprises, some of them probably technologically outdated. Such information should include technical information on processes, technologies, raw materials, wastes, products, etc. As this is a first assessment, all of the most up to date information may not have been included; a limiting factor in being able to estimate emission data and costs may be identified in the large number of small operators in the sector; the iron and steel industry in the People’s Republic of China is growing very fast but is also changing very fast. It is probable that some of the conclusions reached in the present report could be not valid any more in the near future.

The evaluation of the cost-effectiveness of the proposed technical options for reducing PCDD/PCDF releases from the Iron & Steel Industry in China have been performed considering the year 2004 as the baseline scenario because the available dioxin inventory in China has been calculated for the base year 2004. However, information about the distribution of sinter plants and EAFs in China is available for the year 2005. It is interesting to note that the production of crude steel in 2005 was 349.4 million tons, approximately 24.6 % higher than the 280.5 million tons of the previous year. This gives an idea on how fast the Iron and Steel industry is growing and changing in China.