Abstract:Lithium was extracted from salt lake brine with mixed solvent system consisting of extraction agent of TBP, synergistic solvent extraction agent of MIBK, co-extraction agent of FeCl3, and diluent of sulfonated kerosene. The optimum solvent extraction conditions include 40%TBP 20%MIBK 40% sulfonated kerosene, O/A=2.5, n(Fe3 /Li )=2.5, and original H concentration of 0.04 mol/L. The results show that single-stage lithium solvent extraction rate is 91.21%, and magnesium solvent extraction rate is 2.10% with separation coefficient ( ) of 483.05. New extracting complex formation is demonstrated by chemical analysis and IR spectra, and the formation is LiFeCl4?4TBP?MIBK inferred by slope method. Extraction processes are discussed based on ion-pair extraction theory. This mixed system is demonstrated to extract lithium from chloride salt lake with high Mg/Li ratio and low acidity.