离子液体体系卤水提锂的洗涤工艺研究

溶剂萃取法是盐湖提锂的重要工艺方法。采用磷酸三丁酯（TBP）/1-丁基-3-甲基咪唑双三氟甲基磺酰亚胺盐（[C₄mim][NTf₂]）离子液体体系对高镁锂比盐湖卤水中的锂进行萃取分离提取实验,对负载有机相的洗涤和反萃过程进行了研究。萃取实验：在TBP与[C₄mim][NTf₂]体积比为9∶1、相比（有机相与水相的体积比）为2∶1条件下,锂离子与其他离子的分离系数分别为β（锂/钠）=94.70、β（锂/钾）=148.85、β（锂/镁）=131.81。洗涤实验：系统考察了洗涤剂种类及浓度、相比、洗涤次数等因素对杂质离子洗脱率的影响,结果发现氯化锂和盐酸的混合溶液是从负载有机相中洗涤除去杂质离子的有效洗涤剂。洗涤过程适宜条件：洗涤剂中氯化锂浓度为4 mol/L、盐酸浓度为0.5 mol/L,相比为5∶1,洗涤次数为2次。反萃实验：用稀盐酸（1.0 mol/L）对负载有机相进行反萃取,在相比为1∶1条件下,单级反萃率达到97.81%。研究表明,离子液体体系作为一种新型萃取体系,在高镁锂比盐湖卤水中提取锂具有较好的应用前景。

Study on scrubbing process of lithium extraction from brine in ionic liquid system

Solvent extraction was considered to be a importing technique for lithium extraction from the salt lake brine.The ionic liquid system containing tributyl phosphate（TBP） and 1-butyl-3-methylimidazolium bistrifluoromethylsulfonimide salt（[C₄mim][NTf₂]） was used to extract lithium ions from salt lake brine with a high Mg/Li ratio.The scrubbing and stripping processes from the loaded organic phase were also studied.In the extraction experiment,under the condition of a volume ratio of TBP to[C₄mim][NTf₂] of 9∶1 and a phase ratio （O/A） of 2∶1,the separation factor βLi/Na,βLi/K and βLi/Mg were 94.70,148.85 and 131.81,respectively.In the scrubbing experiment,the effect of the types and concentration of scrubbing agent,phase ratio and scrubbing times on scrubbing efficiencies were investigated systematically.The results showed that the mixed solution of lithium chloride and hydrochloric acid was an effective scrubbing agent for removing impurity ions from the loaded organic phase.Optimal extraction conditions of the scrubbing process included 4 mol/L LiCl and 0.5 mol/L HCl in scrubbing agent,phase ratio（O/A） of 5∶1 and the scrubbing times of two times.In the stripping experiment,the loaded organic phase was stripped by 1.0 mol/L HCl and the single-stage stripping rate reached 97.81% at the phase ratio（O/A） of 1/1.This study showed that the new ionic liquid system had a good application prospect for extracting lithium from salt lake brine with a high Mg/Li ratio.