为了解决脱硫石膏的大量堆存对环境造成的潜在危害,同时提高脱硫石膏的附加值,采用常压盐溶液水热法以电厂脱硫石膏为原料探究α-半水石膏的最佳合成工艺,重点研究了盐溶液种类及浓度对α-半水石膏的合成过程、合成产物组成及结构的影响。结果表明：在氯化钙、氯化镁盐溶液中,由于同离子效应和硫酸镁离子对的形成,导致半水石膏的形成过程受阻。较高浓度氯化钾和氯化钠盐溶液可使二水石膏发生转晶,其中氯化钾会致使半水石膏过度脱水生成无水钾石膏,氯化钠盐溶液可以使二水石膏转变为半水石膏并维持较长时间,通过比较得出最佳合成工艺为氯化钠溶液质量分数为15%、体系反应温度为95 ℃、固液质量比为1∶4、搅拌速率为150 r/min、合成时间为3 h,可以制得长径比约为5∶1的六方短柱状α-半水石膏。

In order to solve the potential harm to the environment caused by the large amount of desulfurization gypsum,improve the added value of desulfurization gypsum,the atmospheric salt solution water thermal method was used to explore the optimal synthesis process of α-hemihydrate gypsum with the desulfurization gypsum of power plant as raw material.The effect of salt solution type and concentration on the synthesis process,synthesis product composition and structure of α-semi-water desulfurization gypsum was studied.The results showed that in the CaCl₂ and MgCl₂ salt solutions,the formation process of hemihydrate gypsum was hindered due to the same ion effect and the formation of magnesium sulfate ion pairs.The higher concentration of KCl and NaCl salt solution can transform the dihydrate gypsum,wherein KCl will cause the hemihydrate gypsum to be excessively dehydrated to form anhydrous potassium gypsum.The NaCl salt solution can convert the dihydrate gypsum into hemihydrate gypsum and maintain it for a long time.By comparing the optimal synthesis process was obtained as follows：NaCl solution mass fraction was 15%,system reaction temperature was 95 ℃,mass ratio of solid to water was 1∶4,stirring rate was 150 r/min and synthesis time was 3 h.Under the conditions,hexagonal short columnar α-hemihydrate gypsum with an aspect ratio of about 5∶1 was obtained.