Selective separation of lithium from high Mg/Li ratio brine using single-stage and multi-stage selective electrodialysis processes

Lithium is an essential material in the energy and electronics industry. As abundant lithium resources, lake brines are exploited largely to extract lithium. Selective electrodialysis (S-ED) is a booming technology to recover and separate lithium from brines with high Mg/Li mass ratio. The effects of current, temperature and total dissolved solids (TDS) concentration of brine on the recovery rate of lithium, selective migration ratio, current efficiency and energy consumption were investigated by single-stage S-ED processes. The results confirm that a high current below limiting current density (LCD) could increase both the recovery rate of lithium and separation performance. Under a high temperature, the ion separation of lithium and magnesium decreases obviously but the recovery rate of lithium changes barely. Reducing TDS concentration has almost no effect on ion migration but increases energy consumption. Then according to the determination of LCD, a four-stage S-ED process with stepwise adjustment of current was conducted. The recovery rate of lithium could be obtained 90% with a decrease of Mg/Li mass ratio from 9.85 to 0.57.