用盐酸溶解工业磷石膏重结晶法制备硫酸钙晶须

Preparating of Calcium Sulphate Whisker Using Phosphogypsum by Recrystallization

研究了以磷石膏为原料，以盐酸溶解、重结晶法制备高纯硫酸钙晶须。采用常规方法、XRD和扫描电镜分析和表征磷石膏原料和硫酸钙晶须产品。结果表明，盐酸溶解、重结晶法制备硫酸钙晶须的最优条件为：固液质量体积比50g／500mL，溶解温度约70℃，HCl浓度2．0～2．5mol／L，反应时间1．0h；得到高纯硫酸钙后，加入体积分数为1．0％的HCl溶液，同时加入质量浓度0．5g／L的MgCl2溶液，加热至沸腾（约95℃），待溶液中长出絮状物后继续反应1．0h，快速过滤干燥即得硫酸钙晶须产品，产品中硫酸钙质量分数大于99．0％，白度大于95．0％，晶须直径1～4μm，长度20-400μm，长径比达100。重结晶法制备硫酸钙晶须对磷石膏质量及反应条件精度要求较低，易于实现规模化工业生产。

The high purity calcium sulfate whisker （CSW） was prepared using industrial phosphogypsum by hydrochloric acid dissolution and recrystallization. The raw material and CSW were analyzed and characterized by conventional method,XRD and scanning electron microscopy. The results show that the optimum conditions for preparating CSW are that solid-to-liquid ratio of 50.00 g/500 mL,reaction time of 1 h, dissolution temperature of over 70.0℃,and hydrochloric acid concentration of 2.0--2.5 mol/L. The high purity calcium sulfate prepared is mixed with 1.0% HCl solution and 0.5 g/L MgCl2 solution, then is heated to 95℃. After the whisker appearing, the reaction continues for 1.0 h, then the whisker is quickly filtered and dried. The whisker white and purity are over 95.0%and 99%. The whisker diameter is 1-4 μm,and the length is 20-400 nm,the ratio of length-to-diameter is 100. The recrystaUization method has no high requirements for phosphogypsum and reaction conditions,and is easy for large scale industrial production.