晶形对磷石膏性能的影响

采用实验室模拟二水物湿法磷酸工艺制备不同晶形的磷石膏,测试其过滤性能和洗涤效果,然后将磷石膏充分水洗并煅烧成磷建筑石膏,测试其物理力学性能及微观形貌.结果表明:粗大斜方板状结晶的磷石膏过滤性能和洗涤效果最佳,磷石膏中可溶磷含量最少,胶结材的标准稠度需水量最大,绝干抗压强度最低;长径比(5~8):1的棱柱状结晶的磷石膏过滤性能较好,胶结材的性能最佳;细小的薄片状或细长的针状、棒状结晶的磷石膏过滤和洗涤性能最差,其胶结材的性能居中.从兼顾磷酸生产和磷石膏建材资源化利用出发,棱柱状结晶应为磷石膏晶形调控的方向.

Influence of crystal morphology on the performance of phosphogypsum

Phosphogypsum with different crystal morphology were prepared by simulating wet-process phosphoric acid production by the dihydrate process in laboratory, then the filtration performance and washing effect of phosphogypsum were tested> after that they were calcined to building plaster after adequate washing, their physical and mechanical properties were tested, phosphogypsum crystal morphology and its microstructure were observed. The results showed that: the filtration performance and washing effect of phosphogypsum with orthorhombic plate shape crystalline were the best,the water soluble P2O5 content in phosphogypsum was the l*wehasilte the water requirement of the standard consistency of its cementitious binders was the greatest,and the dry compressive strength was the lowest. The filtration performance of prismatic crystalline phosphogypsum with (5~8):1 length-diameter ratio was also good, and the physical and mechanical properties of its cementitious binder was the best: The filtration and washing performance of tiny thin sheet or slender needle or stick crystalline phosphogypsum was the worst,and the performance of its cementitious binder was the medium. The phosphogypsum crystal which can balance the production of phosphoric acid and phosphogypsum utilization in building materials should be regulated to prismatic crystallization.