Al^（3＋）对二水硫酸钙结晶动力学影响的研究

The Effect of Aluminium on the Crystallization of Gypsum from Phosphoric Acid Solution

本实验采用化学纯磷酸二氢钙和硫酸为原料，模拟湿法磷酸生产中二水硫酸钙的结晶过程，应用粒数平衡技术，改进的实验数据分析方法，在ＭＳＭＰＲ结晶器中研究了酸中杂质Ａｌ３＋对二水硫酸钙的结晶动力学及结晶习性的影响、结果表明Ａｌ３＋对二水硫酸钙的结晶动力学有很大影响，且使二水硫酸钙晶体变小变短。并发现存在－Ａｌ３＋浓度极值，低于此浓度，二水硫酸钙成核速随Ａｌ３＋浓度的增加而增大，成长速率则随Ａｌ３＋浓度的增大而减小，高于这个浓度，则情况相反．

The influence of aluminium on the crystallzation kinetics and the crystal habit of gypsum in phosphoric acid solution have been stuclied in a continuous MSMPR crystallizer.Pure mono-calcium phosphate sotution and reagent grade sulphuric acid have been used for simulating the crystallization process of gypsum.The results indicate that aluminium has great influence on the kinetics of gypsum.Furthermore.it causes gypsum crystal to become smaller and shorter.A optimum aluminium concentration has been found,below it.the nucleation rate of gypsum increases with aluminium concentration,while the growth rate decreases.above it,adverse effects occur.