脱硫石膏作为电厂最大的固体废弃物之一，对其进行研究将其回收利用具有重要的意义。以电厂干法脱硫石膏为原料，采用将亚硫酸钙氧化并重结晶的方法制备二水石膏（CaSO4·2H2O），以用于水泥缓凝剂。考察了溶液pH、液固比（质量比）、催化剂用量、空气流速、反应时间等因素对亚硫酸钙氧化转化率的影响。得到亚硫酸钙氧化为二水石膏的最佳工艺条件：溶液pH为4~5、反应时间为1.5 h、催化剂用量（亚硫酸钙与催化剂的质量比）为7.5、空气流速为0.15 m3/h、液固比为10∶1。在此条件下，亚硫酸钙转化率接近100%。实验得到的二水石膏产品晶形良好、便于过滤，为后续工业化放大奠定了基础。

The recycle and reuse of desulfurization gypsum as one of the largest solid emissions from power plants was important to environmental protection.With dry process desulfurization gypsum of the power plant as raw material，dihydrate gyps um（CaSO4·2H2O） was prepared by oxidizing and recrystallizing calcium sulfite for use as cement retarder.The influences of factors，such as pH of solution，ratio of liquid to solid（mass ratio），amount of catalyst，air velocity and reaction time，on oxidation conversion of calcium sulfite were investigated.The optimum conditions of prepared CaSO4·2H2O from oxidized calcium sulfite were confirmed as follows: the pH of solution was at 4~5，the reaction time was 1.5 h，the amount of catalyst（the mass ratio of calcium sulfite to catalyst） was 7.5，the air velocity was 0.15 m3/h and the ratio of liquid to solid was 10∶1.Under the conditions，the oxidation conversion of calcium sulfite was about 100%.The CaSO4·2H2O product could be further used in industrial production with nice crystal forms and good filterability.