湿法磷酸萃取制备磷酸二氢钾的研究

开发了以湿法磷酸和氯化钾为原料，利用有机溶剂萃取法制备高品质磷酸二氢钾的新工艺。研究了溶配过程氯化钾的加入量对脱氟的影响和萃取时间、萃取温度、相比、氯化钾与磷酸物质的量比等对磷酸、盐酸的萃取率与硫酸根、铁离子、氟离子等杂质的脱除率的影响；以及洗涤相比对五氧化二磷洗涤率的影响，确定了适宜的工艺条件。实验表明：在萃取温度为 60 ℃、萃取时间为 30 min、相比为3.0、氯化钾与磷酸物质的量比为1.0、洗涤相比为12的条件下，五氧化二磷收率可达95.98%以上，产品磷酸二氢钾纯度可达96.75%以上。

Study on preparation of potassium dihydrogen phosphate from wet-process phosphoric acid by solvent extraction method

A new process for preparation of high-quality potassium dihydrogen phosphate（KDP） by organic solvent extraction method with wet-process phosphoric acid and potassium chloride as raw materials was developed.The influences of the addition amounts of potassium chloride on defluorination in the dissolution process were analyzed，and the influences of extraction temperature，extraction time，phase ratio，and the amount-of-substance ratio of phosphoric acid to potassium chloride etc.on the extraction rates of H₃PO₄ and HCl，as well as on the removal rates of SO₄²⁺，Fe³⁺，and F^- etc.were analyzed.According to the influences of phase ratio on washing rate of P₂O₅，the suitable technological conditions were confirmed.Results showed that when the extraction temperature was 60 ℃；extraction time was 30 min；phase ratio was 3.0；amount-of-substance ratio of potassium chloride  to phosphoric acid was 1.0；and phase ratio of washing was 12，P₂O₅ yield could reach over 95.98% and the purity of product KDP was more than 96.75%.