溶剂萃取法净化盐酸法湿法磷酸的研究进展

Research progress purification of solvent extraction of wet-process phosphoric acid by hydrochloric acid route

盐酸法湿法磷酸路线相比硫酸法具有环保和低品位矿适应性优势。综述了溶剂萃取法净化盐酸法湿法磷酸的典型IMI流程、进展与现状和常用溶剂的优缺点;评述了盐酸法路线的固有弊端并提出了相应的解决办法与建议。IMI流程的步骤为酸解、溶剂萃取、浓缩、萃取剂回收。溶剂萃取是净化的核心步骤,常用萃取剂有正丁醇和/或异戊醇、磷酸三丁酯等。磷酸三丁酯相较低碳醇具有对磷酸萃取能力强、选择性高、溶解度小等优点。盐酸法路线有净化磷酸浓度低及盐酸、氯化钙废液利用困难和设备防腐要求高的固有弊端,虽可采用如微化工精确控制等手段,但仍无法完全克服。经分析认为盐酸法路线在特定地理区域或特定时代背景下,才有可能大规模工业化应用。

The hydrochloric acid route for producing phosphoric acid has the advantages of environmental protection and lowgrade ore adaptability compared with the sulfuric acid route.The steps of typical IMI process for purification of the hydrochloric acid route phosphoric acid by solvent extraction was reviewed this paper.The progress and current situation of the solvent extraction method was discussed.The advantages and disadvantages of commonly used solvents were presented as well.The inherent disadvantages of hydrochloric acid route were reviewed and the corresponding solution and suggestion were proposed.The steps of IMI process were acidulation,solvent extraction,concentration and extractant recovery.Solvent extraction was the core step,in which n-butanol and/or isoamyl alcohol and tri-n-butyl phosphate were commonly used as the extractants.Tri-nbutyl phosphate had the advantages of stronger extraction ability,higher selectivity and lower solubility compared with low aliphatic alcohols.The hydrochloric acid route encountered the inherent disadvantages of dilute purified phosphoric acid with hydrochloric acid,difficult utilization of CaCl2 waste liquid and high anticorrosion requirement of equipment,which could not be completely overcome even though the micro-chemical technology of high precise control was applied.It could be concluded that the large-scale industrial application of hydrochloric acid route may be put into action under the specific geographical area or specific era background.