Simultaneous Recovery of Magnesium and Lithium from Salt Lake Brine by Membrane Electrolysis for Resource Utilization

The extraction of lithium and potassium from salt lakes has led to the generation of substantial amounts of magnesium-rich waste streams. These by-products, with their high magnesium content, have contributed to severe environmental degradation in salt lake regions. Therefore, recovering and utilizing magnesium from salt lake resources is a crucial challenge for achieving sustainable development. In this study, magnesium and lithium were separated from evaporated brine—obtained via solar pond technology—using membrane electrolysis. Magnesium was converted into Mg(OH)2 as a flame retardant, while lithium was refined into battery-grade Li2CO3. The final products exhibited high purity, exceeding 99.5% for Mg(OH)2 and 99.99% for Li2CO3. This work systematically investigated the influence of electrolysis temperature on the physicochemical properties of Mg(OH)2 extracted via membrane electrolysis. The variation in electrolyte temperature was also analyzed in relation to other process parameters, such as electrolyte concentration, current density, and processing time. Results demonstrated that the electrolysis process could maintain a favorable operating temperature through self-heating, even under ambient conditions. Using this electrolysis approach for magnesium–lithium separation from brine, extraction rates of 95.86% for magnesium and 67.46% for lithium were achieved.