Recovery of both magnesium and lithium from high Mg/Li ratio brines using a novel process

In this study, an integrated process was developed to separate and simultaneously recover both magnesium and lithium from brines. This technology includes production of magnesium-aluminum-carbonate-layered double hydroxide materials (MgAlCO3-LDHs), removal of boron, CO32–, and SO42 −, and precipitation of lithium carbonate. Factors such as water addition ratio, Mg2 +/Al3 + mole ratio, and lithium loss rate were investigated during MgAlCO3-LDHs production. The effects of lithium concentration and CO32 −/2Li+ mole ratio on lithium carbonate precipitation were also studied. It was found magnesium and lithium had been effectively separated after MgAlCO3-LDHs production. The magnesium content in brine displayed a notable decrease from 117 g/L to less than 0.02 g/L with a lithium yield more than 95.0%. To concentrate lithium and precipitate lithium carbonate, 96.46% of boron, 99.2% of the CO32 −, and 99.56% of the SO42 − impurities were removed from the brine by adsorption, acidification, and precipitation, respectively. The lithium yield was more than 91% when lithium concentration in brine approximated 27 g/L and the CO32 −/2Li+ mole ratio was 1.2. The purity of this product was 99.70%. Overall, this study provides an interesting vision for future integrated utilization of magnesium and lithium resources from salt lake brines with high Mg/Li ratio.