| Sintering process is the main source of SO2 emissions in iron and steel company, which accounts for approximate 60% of the total emission in iron and steel works. Controlling SO2 emission from sintering is extremely important for reducing pollution in iron and steel works. Accelerating the implementation of sintering flue gas desulfurization, reducing SO2 emission of the sintering process is a inevitable requirement of the sustainable development of the iron & steel industry, is an important problem needed to be resolved urgently as well as a effective way to improve the international competitiveness of our iron and steel enterprisesIn response to our country's policy on the reduction of the total SO2 emission and constructing environment-friendly enterprises, Pingxiang iron and steel corporation is about to remake the existing flue gas system of the two 90 m2 sintering machine, so as to construct its sintering flue gas desulfurization facilities. Thus, research on the characteristics of the sintering flue gas from Pingxiang 2×90m2 sintering machine and the corresponding desulphurization process, the construction of a reasonable sintering flue gas desulfurization facilities, can reduce the total SO2 emission in Pingxiang Iron and Steel Co., Ltd., which complies with our country's increasingly severe SO2 emission situation and makes a contribution for the improvement of the surrounding air quality, and provide scheme for the environment-friendly economic development.Through the research of the sintering flue gas from Pingxiang 2×90m2 sintering machine by a simulation test and a lime-gypsum dynamicwave desulphurization process, the following conclusions can be obtained:(1) The research of simulated sintering shows:SO2 content in the flue gas in the ignition and heat preservation period emerges a small peak (up to 300ppm) due to the combustion of the ignition fuel gives off a small amount of SO2. Then, the SO2 content decreases to 150～200ppm, and maintains for some time. As the overwet layer of the sinter bed disappears, the SO2 content in the flue gas increases rapidly, and emerges the second peak (up to 1256 ppm). When the temperature of the flue gas begins to increase, the overwet layer has already disappeared at this time. As the temperature of the flue gas increases continuously, the SO2 content decreases rapidly to zero.(2) The research on the characteristics of the sintering flue gas from Pingxiang iron and steel company shows:the instability of the sintering process and fluctuations in raw sintering material, result in a substantial fluctuation and a high frequency in the amount of flue gas^ flue gas flow,dust concentration and SO2 concentration of the Pingxiang Iron and Steel Co., Ltd., and the characteristics of head flue gas between the two sintering machines are not consistent. The change in the total gas flow comes up to over 40%; while the quarterly SO2 average concentration changes in the range between 889 and 2240 mg/m3, while it may changes between 600 and 6000 mg/m3 in the single day.(3) Through the research on the domestic desulfurization technology and comprehensive considerations over the flue gas characteristics of the sintering plant in the Pingxiang Iron and Steel Co. Ltd.,the maturity of existing desulfurization process and the safety and reliability of operating system, combined with the availability of local desulfurization agent and so on, we choose the lime-gypsum dynamicwave desulphurization process to deal with the flue gases of the 2*90m2 sintering machines, using a single tower with two reverse nozzle desulfurization system, its designed capacity is of flue gas volume of 2*630000m3/h (working condition,110℃), SO2 concentration is 1440 mg/m3, the designed SO2 removal efficiency≥93%(guaranteed value≥90%), the flue gases after treatment release into the atmosphere through the Chimney corrosion (H: 70 m, D:4.5 m) of the desulphurization systems.(4) The desulphurization system in the Pingxiang Iron and Steel Co. Ltd. mainly consists of flue gas system,the absorbent preparation system,oxidation system and desulfurization by-product disposal system. The gas from the main exhaust fan of sintering machine is introduced into a tower where desulfurization reaction happens. The desulfurization agent comes from the absorbent Preparation System so, in the flue gas system sintering flue gas and desulfurization agent are fully mixed and reacted, then through the oxidation system, the desulfurization by-products will be addressed in desulfurization by-product processing system. The desulfurizated flue gas emit into air through the FRP corrosion chimney at the top of the reaction tower, which can meet the national emission requirements.(5) Using lime-gypsum dynamic wave desulfurization processing to deal with the sintering flue gas coming from 2×90m2 sintering machines in Pingxiang iron and steel plant, lime (CaO) are used after transforming to 20wt.% Ca(OH)2 slurry as the desulfurization agent. Desulfurization system quicklime (CaO,80%) consumption is 1.3 t/h, the power consumption is 2400 kW·h/h, annual power consumption is 18.06 million kW·h. The water consumption of Desulfurization process comes from water supply system in the Ping Steel sintering plant, about 39 m3/h, for the annual water consumption is 290,000 m3. The parameters of sintering flue gas treated by desulfurization system are in the following:flue gas volume:958,000 m3/h (standard state, wet), temperature:40℃, pressure: 100 kPa, H2O (Vol.%):7.37. Process Water is outleted mainly by gas (98.5% of total water consumption), and the remaining small amount is brought out by the desulfurization end products (gypsum). The whole desulfurization system is without waste water efflux.(6) The major cost of desulfurization system is sorbent consumption, system power, water and personnel costs for a total of 22.4778 million RMB/a. The desulfurization system (removal efficiency of 93% by total) runs, the cost of per ton of sinter increased by 7.2 RMB. Economic benefits gained are mainly due to the reduction of SO2 emission desulfurization costs (7994300 RMB/a) and the desulfurization by-products on sell. However, taking measures for desulphurization to reduce the SO2 emission concentration around the enterprise, the business environment and the air quality are improved, so as to set the environmently-friendly corporate image, promote the reputation of company, and obtain environmental and social benefits.
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