Selective lithium recovery from lithium precipitation mother liquor by using a diketone-based solvent

Lithium recovery from lithium precipitation mother liquor is an important point for improving lithium resource utilization efficiency. In this study, a modified beta-diketone based organic solvent was developed. DBM was selected as extractant, which has the advantage of low cost compared to fluor-diketones. Organic phosphate TBP was used instead of traditional alkylphosphine oxide as co-extractant. The results show that TBP has the ability to inhabit the extraction of sodium so that it is positive for separation factor of lithium to sodium. Simultaneously, TBP plays the role of diluent, thus improving two-phase separation performance significantly. The phase separation time is only tens of seconds, which is much less than that of alkylphosphine oxide co-extraction system. Besides, low cost and low viscosity properties of TBP avoid the limitation of additive amount, which means that it has the industrial feasibility to improve the extraction performance by increasing TBP concentration. The developed extraction solvent has the combination sequence of H+ > > Li+ > > Na+. By using optimized solvent of 0.4 mol/L DBM and 1.2 mol/L TBP dissolved in sulfonated kerosene, single-stage lithium extraction rate is 99.96 % and separation factor of lithium to sodium reaches >160,000 at the O/A phase ratio of 1:1.