湿法磷酸萃取制取高品质磷酸二氢钾工艺研究

磷酸二氢钾在当前的磷酸盐工业中具有重要的实用价值，其应用涉及到工业、农业、医药以及食品等多个行业。以尽可能低成本的原材料与更简易的工艺流程来生产具备更高品质特性的磷酸二氢钾为时下所需。以湿法磷酸与氯化钾为原料，进行了有机溶剂萃取法制备磷酸二氢钾的工艺研究。研究内容包括：在溶配过程中氯化钾与磷酸物质的量比对氟离子脱除率的影响；氯化钾与磷酸物质的量比、反应时间、反应温度以及萃取相比对萃取率及杂质脱除率的影响；不同洗涤相比对五氧化二磷洗涤率的影响；反萃取以及磷酸二氢钾浓缩结晶的相关工艺。通过实验确定湿法磷酸萃取制取高品质磷酸二氢钾适宜工艺条件：反应温度为60 ℃，反应时间为30 min，氯化钾与磷酸物质的量比为1.0，洗涤相比为12。在此工艺条件下所得磷酸二氢钾产品纯度高达97%，达到磷酸二氢钾农用级优等品标准的要求，同时五氧化二磷回收率可达到96%。

Preparation of high-quality potassium dihydrogen phosphate from wet-process phosphoric acid by extraction method

Potassium dihydrogen phosphate has an important practical value in the current phosphate industry，and it was also applied in many industries，such as industry，agriculture，pharmacy，and foodstuff.To produce higher-quality potassium dihydrogen phosphate with lower cost of raw materials and simpler process is today′s need.Potassium dihydrogen phosphate was prepared by organic solvent extraction process with wet-process phosphoric acid and potassium chloride as raw materials. The study contents included：the influence of amount-of-substance ratio of potassium chloride to phosphoric acid on removal rate of F- during the solution preparation；the influence-of-amount of substance ratio of potassium chloride to phosphoric acid，reaction time，reaction temperature，and extraction phase ratio on extraction rate and impurities removal effect；the influence of different washing phase ratios on washing rate of the high-quality P2O5；relevant back-extracted and potassium dihydrogen phosphate concentrated crystallization processes etc..Optimum conditions for preparing high-quality potassium dihydrogen phosphate were obtained as follows:reaction temperature of 60 ℃，reaction time of 30 min，amount-of-substance ratio of potassium chloride to phosphoric acid of 1.0，and washing phase ratio of 12.Under those conditions the product purity was 97% and the recovery rate of P2O5 reached 96%，which met the first grate requirement of agricultural standard.