磷石膏作为湿法磷酸工业排放的大宗工业固体废物，随着磷酸工业的产生而产生，大量的磷石膏需要进行无害化处理或资源化利用。用其生产水泥缓凝剂是综合利用途径之一，但因其含有水溶性磷和氟等有害元素，因此需要添加其他物质对其进行改性。研究了改性工艺条件对改性效果的影响，结果表明：在电石渣改性磷石膏的反应中，反应时间和电石渣加入量对改性结果有较大的影响，而反应温度相较于反应时间和电石渣加入量则影响较小。在反应时间达2 h，电石渣加入量大于0.3%时，可有效去除磷石膏中的可溶性磷和氟，达到GB/T 21371—2008《用于水泥中的工业副产石膏》对磷石膏的性能要求。

Phosphogypsum is a large?鄄scale industrial solid waste discharged from the wet?鄄process phosphoric acid industry. With the production of the phosphoric acid industry，a large amount of phosphogypsum needs to be harmlessly treated or utilized.It is one of the comprehensive utilization ways to use it to produce cement retarder.But it contains harmful elements such as water?鄄soluble phosphorus and fluorine，therefore，it is necessary to add other substances to modify it.The effect of modification process conditions on the modification effect was studied.The results showed that in the reaction of calcium carbide slag modified phosphogypsum，the reaction time and the adding amount of calcium carbide slag had a great influence on the modification results，while the reaction temperature had little influence compared with reaction time and adding amount.When the reaction time was up to 2 h and the adding amount of calcium carbide slag was more than 0.3%，the soluble phosphorus and fluorine in the phosphogypsum could be effectively removed，which met the performance requirements of the gypsum gypsum in Industrial By?鄄product Gypsum Used in Cement，GB/T 21371—2008.