“氨法”纯化磷石膏水热反应制备硫酸钙晶须

以磷石膏为原料,采用"氨法"除杂纯化和水热反应制备硫酸钙晶须,考察磷石膏除杂及制备硫酸钙晶须的工艺条件。结果表明:当磷石膏、碳酸氢氨和氨水的配料比为1.0∶1.0∶0.8,温度T_1、T_2和T_3均为25℃,盐酸浓度2.5 mol·L~(-1),碳酸钙、盐酸的配料比为1∶2.5时,为其除杂最优条件;在此条件下,磷石膏经纯化处理后得到高纯度硫酸钙,其转化率为86.93%,纯度和白度分别是99.5%和99.3%。水热反应的最优条件为反应时间5 h、浆料质量浓度为8%和反应温度150℃;在此条件下制得的硫酸钙晶须平均长径比125.84,单个晶须长径比最大为169.66,对应晶须长度为554.43μm。

Preparation of Calcium Sulfate Whisker via Hydrothermal Reaction From Phosphogypsum Purified by Ammonia Method

The calcium sulfate whisker was prepared via hydrothermal reaction from phosphogypsum which was purified by ammonia method. And technological conditions for purifying phosphogypsum and preparing calcium sulfate whisker were investigated. The results showed that the high-purity calcium sulfate with conversion rate of 86.93%, purity of 99.5% and whiteness of 99.3% , was prepared when mixed ratio of phosphogypsum, ammonium bicarbonate and ammonia was 1.0:1.0:0.8, temperatures T1, T2, T3all were 25 ℃, concentration of hydrochloric acid was 2.5 mol·L-1, mixed ratio of calcium carbonate and hydrochloric was 1:2.5. And the calcium sulfate whisker with average length-diameter ratio of 125.84, individual whisker length-diameter ratio of 169.66,the length of 554.43 μm, was prepared. The technological conditions for preparing calcium sulfate whisker were as follows: reaction time 5 h, slurry concentration 8%, reaction temperature 150 ℃.