二水磷石膏转化为半水石膏的工艺研究

摘要

中国磷肥工业每年排放出约5000万t的二水磷石膏,这些磷石膏中以水份和P2O5为主的杂质含量过高限制了磷石膏的综合利用.本文提出用化学转晶法将二水磷石膏转化为半水石膏,回收其中的P2O5并且大大降低石膏中的水份含量,为磷石膏的利用找到了一条经济适用的途径.实验研究了H2SO4浓度、温度和液固比对二水磷石膏转化为半水石膏的影响,得出最佳的转晶工艺条件为H2SO4浓度12.25％,转晶温度95℃,液固比2.8:1,在此条件下得到了纯度很高的半水-无水混合石膏.%The China Phosphate Industry generated about 50 million tons dehydrate phosphogypsum a year; the high content of impurities especially H2O and P2O5 in the phosphogypsum limited its comprehensive utilization. This work using chemical method transformed dehydrate phosphogypsum into hemihydrate-anhydrate phosphogypsum, recycling the P2O5 and reducing water content, and find an economic method for the use of phosphogypsum. This paper studied of the influence of sulfuric acid concentration, temperature and liquid-solid ratio on the transformation, and finded 12.25(wt)%,95℃, liquid-solid ratio of 2.8:1 was the ideal transformation conditions, and obtains high purity of hemihydrate-anhydrate phosphogypsum.