蒸压处理对磷石膏中石膏相脱水性能的影响及其过程的研究

Study on the dehydration performance influences and process of the gypsum phases in phosphogypsum using autoclave

一般认为,在蒸压处理过程中,磷石膏有3种晶相:二水硫酸钙、α型半水硫酸钙、无水硫酸钙。讨论了在不同温度和不同保温时间蒸压条件下,磷石膏的相转变过程及其产物的物理性能。结果表明,部分磷石膏首先直接脱水成β型半水硫酸钙,然后二水硫酸钙和β型半水硫酸钙转变成β型半水硫酸钙,最后全部转变为无水硫酸钙。同时还探讨了可溶性磷、氟对磷石膏脱水过程及其脱水相性能的影响,发现P/F杂质形成的难溶性磷酸钙和氟化钙影响硫酸钙的脱水形貌。

Generally speaking, there are three crystalline phases-calcium sulfate dihydrate,α-calcium sulfate hemihydrates and anhydrous calcium sulfate in the autoclave process. The phase transition of phosphogypsum and the physical properties of the products were studied at different temperatures and in different holding time in this paper. The results show that a part of phos- phogypsum is dehydrated to give β-calcium sulfate hemihydrates,and then the rest of calcium sulfate dihydrate transformed into a-calcium sulfate hemihydrates together withβ-calcium sulfate hemihydrates,finally changed into anhydrous calcium sulfate entire- ly. Meanwhile,the influences of the dehydration process and the properties of the dehydrated phase that dissolubility P and F worked on phosphogypsum were discussed. The results showed that the insoluble calcium orthophosphate and calcium fluoride pro- duced by the P/F impurity had an influence ou the morphology of calcium sulfate dehydrate.