5％氯化钙存在下高硫煤还原磷石膏实验研究

摘要

Phosphogypsum,waste slag derived from phosphate fertilizer industry doping with 5%(mass fraction) CaCl2 was used as raw material, purged with N2 and then calcined under the presence of high-sulfur coal as reductant to prepare CaS and CaO.The contents of CaS and CaO in the product were analyzed by iodine quantity method so as to investigate the reduction rate of calcium sulfate.The effects of raw material mix ratio, calcining time, calcining temperature, and particle size etc. on the reduction of phosphogypsum were studied.Based on these studies, orthogonal experiments were conducted to find out the optimum process conditions for obtaining CaS and CaO by reducing phosphogypsum,which are as follows: amount-of-substance ratio of CaSO4 to C was 1:1.3, calcining temperature was 900℃. ,and calcining time was 2.5 h. Under those conditions the reduction rate of CaSO4 in phosphogypsum could reach more than 98%.The doping of 5% CaCl2could decline the reductive decomposition temperature of phosphogypsum.%以磷肥工业废渣磷石膏为原料,在磷石膏中掺入5％氯化钙(以质量分数计),以高硫煤为还原剂,在氮气吹净空气后焙烧还原磷石膏制备硫化钙、氧化钙,并采用碘量法分析产物中硫化钙、氧化钙的含量,考察硫酸钙的还原率.研究了原料配比、焙烧时间、焙烧温度、颗粒细度等因素对还原磷石膏的影响.在此基础上进行了正交实验,得到还原磷石膏制备硫化钙、氧化钙的优化工艺条件:硫酸钙与碳物质的量比为1:1.3、焙烧温度为900℃、焙烧时间为2.5 h,在此条件下,磷石膏中硫酸钙的还原率可达到98％以上.在磷石膏中掺入5％氯化钙能降低磷石膏的还原分解温度.