Extraction of Lithium from Salt Lake Brine

Lithium has been regarded as a new kind of strategic energy for its unique physicochemical property with the rapid development of the new energy industry. The demand for lithium increases every year and the lithium extraction and separation technology has attracted more and more interests. China is rich in lithium resource from salt lake brine, but it has not been exploited effectively due to the difficulty by high Mg/Li ratio. Thus, there are crucial research value and strategic significance to study the extraction of lithium from high Mg/Li ratio salt lake brine. In this review, the research status of popular lithium extraction technology from salt lake is summarized, including precipitation, solvent extraction, ion-sieve adsorption, nanofiltration and electrodialysis methods. The advantages and characteristics of the methods above are reviewed and the influence of high Mg/Li ratio on lithium separation is discussed. Moreover, the emerging solvent extraction using ionic liquid extractant and electrodialysis technology with monovalent selective permeability ion exchange membrane used to extract lithium from high Mg/Li ratio salt lake brine are introduced in detail. The two technologies exhibit great research significace and wide application prospects. The former has the potential to develop high effective lithium extractants due to the designability of ionic liquid structure and function. The current research shows that the latter could even reduce the Mg/Li mass ratio from 150 to 8.0 for the simulated brine, and simultaneously, the Li+ recovery reaches 95.3%. Finally, the existing problems and development directions of lithium extraction from high Mg/Li ratio salt lake brine in the future are discussed.