钙芒硝石膏深度提纯工艺的研究

钙芒硝石膏是工业上采用溶浸法生产元明粉的副产尾矿，与脱硫石膏和磷石膏等工业副产石膏相比其杂质含量高、纯度低、利用价值低。采用酸浸-重结晶工艺对钙芒硝石膏进行提纯，通过酸浸去除钙芒硝石膏中的酸溶性杂质，并将二水硫酸钙（DH）脱水转化为无水硫酸钙（AH），然后控制水化条件，使AH水化为大尺寸的DH晶体，并与小尺寸的酸不溶性杂质分离开来，得到高纯度的二水石膏。研究了硫酸浓度、水化激发剂、液固质量比、反应时间等对石膏提纯的影响。研究结果表明：常压下，在硫酸酸洗液质量分数为35%、反应温度为80 ℃、石膏与硫酸溶液固液质量比为1∶5、酸洗时间为2 h时能有效去除钙芒硝石膏中的酸溶性杂质；在水化硫酸质量分数为5%、硫酸钾质量分数为1.74%、反应温度为25 ℃、固液质量比为1∶6、陈化时间为18 h时能有效去除钙芒硝石膏中酸不溶性杂质，提纯后的石膏纯度可达97%以上。

Research on deep purification process of glauberite gypsum

Glauberite gypsum is the by-product tailings produced by leaching sodium sulfate in the industry.Compared with industrial by-product gypsum such as desulfurized gypsum and phosphogypsum，it has higher impurity content，lower purity and utilization value.Glauberite gypsum was purified by acid leaching-recrystallization process，the acid-soluble impurities in Glauberite gypsum were removed by acid leaching and dihydrate calcium sulfate（DH） was converted into anhydrous calcium sulfate（AH）.Then hydration conditions were controlled to hydrate AH into large-size DH crystals separated from small-sized acid-insoluble impurities to obtain high-purity dihydrate gypsum.The effects of sulfuric acid concentration，hydration activator，liquid-solid ratio and reaction time on purified gypsum were studied.The research results showed that under normal pressure，when the mass fraction of sulfuric acid pickling solution was 35%，the reaction temperature was 80 ℃，the solid-liquid ratio of gypsum and sulfuric acid solution was 1∶5，and the pickling time was 2 h，it could effectively remove acid-soluble impurities in glauberite gypsum.When mass fraction of hydrate sulfuric acid was 5%，mass fraction of potassium sulfate was 1.74%，reaction temperature was 25 ℃，solid-liquid ratio was 1∶6，aging time was 18 h，it could effectively remove acid-insoluble impurities in glauberite gypsum，and the purity of purified gypsum could reach more than 97%.