Selective Recovery of Lithium from Lithium Precipitation Mother Liquor by DBM-TIBP Synergetic Extraction System

Lithium precipitation mother liquor produced during the lithium precipitation process is a typical solution with a high Na/Li ratio. In this work, the dibenzoylmethane (DBM) and triisobutyl phosphate (TIBP) extraction system after saponification with sodium hydroxide was used to selectively recover lithium ions from lithium precipitation mother liquor. Under optimal extraction conditions, the single-stage extraction efficiency of lithium ions reached up to 95%, and the mass ratio of Na to Li decreased from 36 in aqueous solution to 0.7 in the extractant. After washing with ammonium chloride and lithium chloride, the washing efficiency of sodium ions reached up to 98.9% without the loss of lithium ions. The stripping efficiency of lithium ions was 99.6% by three-stage stripping processes with ammonium carbonate, and battery-grade lithium carbonate could be directly prepared by evaporation of the stripping solution, leading to no production of lithium precipitation mother liquor again. Finally, the selective extraction mechanism of DBM-TIBP extraction system was explored by FT-IR and 31P NMR characterizations.