脱硫石膏晶体提纯脱色的研究

Decoloration and Purification of FGD Gypsum Crystal

以H2O-HCl-CaCl2溶液为反应介质采用两步法在常压下对脱硫石膏脱色;考察了HCl浓度、CaCl2浓度、料浆浓度对水热反应时间的影响和转晶温度、转晶时间、料浆浓度对产品白度和收率的影响。得出的较适宜条件为:HCl浓度为1.21mol/L,CaCl2浓度为0.27mol/L,料浆浓度为6.98%,转晶温度25℃、转晶时间18h,该条件下水热反应时间缩短至120min,脱色产品的白度和纯度分别提高至90%和96%。脱色提纯过程的母液反复利用5次后,产品性能与初次配料时无明显差异。以提纯脱色后的脱硫石膏为原料制备的半水硫酸钙晶须白度达到95.22%。

Two step decoloring process of FGD gypsum was studied in H2O-HCl-CaCl2 system at atmospheric pressure. The influence of HCl,CaCl2 and slurry concentration on the hydrothermal time were investigated. The effect of crystal transformation time,temperature,slurry concentration on whitness and yield of decolored FGD gypsum were investigated. The proper operation condition was obtained：concentration of HCl,CaCl2 and slurry are 1. 21 mol / L,0. 27 mol / L and 6. 98%,respectively,crystal tempreture and time are 25 ℃ and 18 h,respectively. Under this condition the hydrothermal time can be shortened to 120 min,the whitness and purity of decolored FGD gypsum can reach 90% and 96%respectively. After 5 cyclies of the mother liquid,there is no significantly negative impact on the product quality. The whitness of CSW（ Calcium Sulfate Whisker） prepared by decolored FGD gypsum reached95. 22%.