A Novel Solvent Extraction System for Lithium Recovery from Underground Brine

In order to effectively recover lithium from underground brine, a novel solvent extraction system [tri-isobutyl phosphate (TIBP)+butyl acetate (BA)+FeCl3+sulfonated kerosene (SK)] is studied experimentally. The effects of organic phase composition, molar ratio of Fe3+ and Li+ [n(Fe3+/Li+)], phase ratio [R(O/A)], temperature and pH in the stage of lithium extraction, as well as NaOH concentration and phase ratio in the stage of back-extraction were investigated. The singlestage extraction rate of lithium at room temperature was about 72% with the solvent extraction system (50% TIBP+ 10% BA+40% SK) under the optimum extractive condition of n(Fe3+/Li+)= 2.0, pH = 2-3, phase ratio R(O/A) = 1.0, and the single-stage back-extraction rate was about 82% under the optimum back-extraction condition 1.3 mol.L-1 NaOH at the phase ratio R(O/A) = 2.0. These results indicate that lithium ion in underground brine can be efficiently recovered by employing a multistage continuous extraction method using centrifuge or mixer settler at these conditions.