Recovery of lithium from salt lake brine with high Na/Li ratio using solvent extraction

Efficient separation of lithium from salt lake brine with high Na/Li ratio is of great importance for the development of new energy industry. Liquid-liquid extraction using β-diketone system was proved to be an effective approach to separate lithium from alkaline metal ions, while the separation effect of lithium to alkali earth ions needs further investigation. In this work we proposed an extraction process using HBTA/TRPO system to recovery lithium from salt lake brine with high Na/Li ratio. The conditions of saponification, extraction, eluting, stripping and regeneration process was optimized by equilibrium experiments. Through the process, lithium, calcium and magnesium were extracted to the organic phase and then stripped step by step to obtain lithium-rich solution, then the stability of the process and organic was tested by cycle experiments, the results indicated the proposed method was effective and stable. Theoretical study based on density functional theory was conducted to expound the extraction selectivity to different metal ions, and the energy change, electrostatic potential and Mulliken charge of the complexes was obtained, the calculated results suggested the stability of the complexes followed the sequence: Mg2+ > Ca2+ > Li+ > Na+ > K+, which is consistent with the experimental results. The present work may provide a novel way to efficiently recover lithium from salt lake brine with high Na/Li ratio.