Study Preparation Of Calcium Sulfide And Its Reaction Process With Sulfur Dioxide

The high concentration of sulfur dioxide is mainly used to prepare sulfuric acid. In recent years, the overproduction of sulfuric acid lead to the problem of lower price and dull of sale. Aimed at the rational use of high concentrations of sulfur dioxide, the new technologies of preparation of calcium sulfide and its reaction characteristics with sulfur dioxide was studied.Using calcium sulfate or calcium sulfite as raw materials, clean coal as reducer, calcium sulfide was prepared by reduction roasting method. The influenceing factors of the preparation of the calcium sulfide such as ratio of raw materials, calcination temperature, calcination time and moisture content of raw materials were studied. When using calcium sulfate as raw material, the yield and purity of calcium sulfide were84.41%and82.60%respectively under the optimum conditions. When using calcium sulfite as raw material, the yield and purity of calcium sulfide in the product were96.52%and99.31%respectively under the optimum conditions. The roasted products were characterized by X-ray diffraction (XRD) analysis, and the result showed that they were mainly calcium sulfide.Using calcium sulfide as reducer, methanol as solvent, sulfur dioxide was removed by oxidation reduction method. The influencing factors of desulfurization process such as reaction temperature, the calcium sulfide content in the methanol, aeration rate of sulfur dioxide, reaction time, stirring speed, the reuse of methanol and sulfur dioxide removal in the absorption series were studied. Under the optimum conditions, the sulfur recovery ration was79.20%in the first absorption process, the two-stage absorption efficiency of sulfur dioxide reached99.5%and the three-stage absorption efficiency of sulfur dioxide reached100%. The recycled methanol had no effect on desulfurization. The products were characterized and confirmed by X-ray diffraction (XRD) analysis. The results show that they are mainly calcium sulfite, sulfur and part of calcium sulfate. Sulfur was separated by Carbon disulfide in the solid, the total mass calcium sulfate and calcium sulfite was85.22%. The studies of desulfurization kinetics show that it is belonged to unreacted shrinking core model and internal diffusions control, and its activation energy is22.96kJ/mol.In order to recycle resources, using the residue from the reaction between calcium sulfide and sulfur dioxide as raw materials, clean coal as reducer, calcium sulfide was prepared by reduction roasting method. The influencing factors of the preparation of the calcium sulfide such as ratio of raw materials, calcination temperature, calcination time and moisture content of raw materials were studied. Under the optimum conditions, the yield and purity of calcium sulfide were98.80%and83.21%respectively.