| The main source of SO2 in steel industry is from sinter process and the coal-burning boilers of self-equiped power plant. So how to control SO2 emission during sintering and electricity generating is the key to deal with the pollution in iron & steel factory. There has been a lot of desulfurization technologies that are used to control SO2 emission for coal-burning boilers of self-equiped power plant, and dozons of technologies has been applied at home and abroad. There are two methods to control SO2 emission during sintering in iron and steel complex in countries abroad:controlling the Sulfur content in the raw materials and desulfurizing fume in the end. At home, the research is still on the initial stage. Study on how to develop a desulfurizing technique with less investment, less operating costs and resource regeneration, is very important. Therefore, adopting the advanced technology to control and reduce the emission of SO2 is a task needing to resolve for the sake of clear production in iron & steel factory.In order to do so, some investigation is undertook to make sure wher the Sulfur comes and whers goes in iron and steel factory, and to know the progress in fume desulfurization at home and abroad. Based on the analysis on the Sulfur flows in steel production, this paper puts forward a new desulfurizing technology:pyrolusit as oxidant and rhodochrosite as additives are used to absorb the SO2 in the fume in sinter process, so as to adjust the pH value of the pulp to make MnSO4. It is actually a new technology. In this technology, the production of MnS04 is connected with the treatment of SO2, so as to remove the reduction roasting process in the production of MnS04, to save energy, and to produce the new resource of H2SO4. At the same time, SO2 is absorbed without harm, and become a new resource. The main research content is as follows:The analytic model of Sulphur flows for a process is established based on the theory of Industrial Metabolism and the method of Material Flow Analysis. It will provide theoretic reference to further research the reducing SO2 pollution letting for iron & steel factory.According to the practical data of an iron & steel factory, the model was used to analyze the Sulphur in the factory, draw the sketch of Sulphur flows, and dissolve the cause and effect. The analysis results are as follows:the SO2 emission is about 1.30kg per ton steel for the main processes, and 1.15kg per ton steel for sinter process.It is essential to FGD in sinter process in the lack of scrap and decline of fuel quality.The reaction thermodynamics and mechanism of desulfurization process with pyrolusite are analyzed. We make sure there are two process of desulfurization:the main reaction as(MnO2+SO2=MnSO4, and the minor reaction (SO2+1/2O2+H2O=H2SO4). Though the minor reaction can promote the desulfurizing process, H2SO4 produced in the reaction cut down the PH value so as to reduce the solubility of SO2 in water, and in this way hold back the operation of the main and reduce the desulfurization efficiency.The experimental study of desulfurization of fume with pyrolusite is done. The technique conditions that affects desulfurizating process and leaching Mn2+process in the system, such as absorbing temperature, ratio of liquid to solid, size of Manganese and content of SO2 in the fume is analyzed. The effect of desulfurization and leaching Mn2+ is studied when rhodochrosite as additives is put in the system to adjust the pH value, so as to make sure the quatity of the additives. Through the experimental study, the technique condtions under which the high desulfurization rate and the rate of leaching Mn2+ can be obtained is set up:the temperature is at 40℃, the ratio of liquid to solid 5:1, the size of Manganese 0.075mm and the ratio of rhodochrosite 20%, and in this way offer the technique support to the middle test.Some deep developing research on the by product of the desulfurization- MnSO4 as fertilizer and feed is done. In the research, Fe and Al is based on the method of Ammonia counteraction; the purification of heavy metal ions is repalced by the Manganese powder; and the insoluble things such as CaSO44 and MgSO can be purified by placing staticly. By the purification, the heavy metal such as Fe and Al, and the insoluble things will arrive the level of trace.The middle test is done to testify the experimental results and speed up the pace of industrial application. The impaction of the desulfurization process has on the environment and the economic benefits is analyzed. The middle test shows that:the whole set of devices runs smoothly; the process for the middle test is reasonable; the desulfurization rate can be above 92% for long time; the the rate of leaching Mn2+ can be over 80%; The product MnSO4 can arrive the fertilizer level (GB1622-86) and feed level (GB5252-876).The desulfurization technology of fume with pyrolusite and rhodochrosite is a technology which meets the current conditions in China, and can be promoted widely. It has practical significance for the treatment of the fume from the sinter process and the boiler that burns coal in China. |
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