萃余酸净化制三聚磷酸钠研究

摘要

为利用湿法磷酸萃取净化过程产生的副产物萃余酸,对萃余酸净化制三聚磷酸钠进行了探索.实验研究了分步中和净化方法,通过控制反应pH,可以除掉磷酸中绝大部分有害杂质.为提高湿法磷酸中和过程的除杂效果,还尝试在中和过程中加入氨水、氯化铵、草酸铵、氟化铵、氟化钠几种沉淀促进剂.初步实验结果表明,氨水和氟化钠对沉淀析出有显著效果,为最佳沉淀促进剂.%In order to utilize the by-product raffinate, produced in the extraction purification of wet process phosphoric acid, the preparation of sodium tripolyphosphate by purification of raffinate was explored.A fractional neutralization purification method was studied.Through control the pH in the reaction , most of harmful substances could be removed from the phosphonc acid.In order to improve the impurity removing effect during the neutralization process of wet process phosphoric acid,several precipitators,such as ammonia,ammonium chloride,ammonium oxalate,ammonium fluoride,and sodium fluoride,were added.Preliminary experiment results showed ammonia and sodium fluoride had obvious effect for the precipitation.