Restore The Decomposition Of Phosphogypsum The Reductant Filter And Influencing Factors

Phosphogypsum is a industrial by-products of wet phosphoric acid production, untreated phosphogypsum stacking not only takes up a lot of land, capital, and many sulfur resources wasted, but will cause serious soil, water, air pollution. Phosphogypsum has been the impact of phosphate fertilizer production technology and safety engineering major problem. coal gangue is associated with coal mining and is separated from washing processes of the solid waste, coal gangue substantial stacking cause serious environmental pollution. Comprehensive utilization of phosphogypsum and coal gangue, the waste change to treasure, both for environmental safety or recovery of resources, or to ensure the development of phosphate fertilizer industry technology security have commercial value and practical significance. In this paper, a large number of tests are maked to selecte excellent reducing agent, and to post graduate material C/S value, reaction temperature and other factors on the selection of reducing agent on the reduction of phosphogypsum and solid decomposition products of P, F content in the effects of phosphogypsum. comprehensive utilization of coal gangue can be made. Main research contents are as follows:(1) selecting reducing agentBy studying on using different reducing agents to deoxidize phosphogypsum,the results show that:the use of coal gangue to do a separate reducing agent, the results are unsatisfactory; compound reducing agente,which mhigh sulfur coal/gangue valu is 1:1 to l:5,and high-sulfur coal to deoxidize phosphogypsum, the results are desirable. From the P and F, the solid product is able to meet the requirements of cement clinker.(2) Investigating the effect factors of deoxidizing phosphogypsum by high sulfur coalThrough studying deoxidizing phosphogypsum by high sulfur coal under the conditions of express warming,experimental study results show that:when the value of C/S is from 0.5 to 0.7, concentration of SO2 and the desulfurization rate of phosphogypsum with the value of C/S of the increase in growth; when the value of C/S is from 0.8 to 1.1, the concentration of SO2 and the desulfurization rate of phosphogypsum with the value of C/S increased reduced; with the value of C/S increased, the decomposition rate of CaSO4 in phosphogypsum. With increasing temperature, the concentration of SO2, the decomposition rate of CaSO4 and the removal rate also increase. High-sulfur coal particle size is from 40 mesh to 120 mesh, the concentration of SO2, the decomposition rate of CaSO4 and the desulfurization rate decreased as the size increase; diameter is>120mesh, the concentration of SO2, the decomposition rate of CaSO4 and the desulfurization rate decreased as the particle size lower. deoxidizing phosphogypsum by high sulfur coal can remove materials soluble P and total F, so that the content P the product of soluble solids and total F are able to meet the requirements of cement clinker, deoxidizing phosphogypsum by high sulfur coal to produce high concentration SO2 and cement clinker is feasible, the feat process control conditions is the value of C/S being from 0.7 to 0.8, the high-sulfur coal particle size being from 100mesh to 120mesh, the temperature being not lower than 1000℃.(3) Investigating the effect factors of deoxidizing phosphogypsum by compound reducing agentUsing reducing agent to deoxidize phosphogypsum, the effect influence of the value of C/S, reaction temperature, reducing agent particle size is basically similar to the use of high sulfur coal. The results show that using the value of mhigh sulfur coal/gangue is 2:1,1:1,1:2 to deoxidize phosphogypsum produceing high concentration SO2 and cement clinker is feasible. The feat process control conditions is C/S being 0.7, reducing agent particle size being from 120mesh to 140mesh, the reaction temperature being not lower than 1000℃. To take full advantage of coal gangue, coal-saving resources should be used the value of mhigh sulfur coal/gangue is 1:1 compound reductant.(4) By comparing S, P, F balance of the response of before and after, results showe that the using composite reductant decomposition Phosphogypsum can get more conducive SO2, reducing quality of the content of CaS in solid and quality of the content of single-product S; not conducive to the removal of P in Phosphogypsum, but there is conducive to soluble P fixed in the solid product, so that the solid product can meet the more high-grade cement clinker requirements; it is conducive to remove F from Phosphogypsum, so that the solid product be able to meet the requirements of high-grade cement clinker.