Liquid Mining of Lithium from Salt Brine Lakes Using Forward Osmosis

Forward osmosis (FO) is a sustainable liquid mining process that can be used to concentrate metal-containing aqueous solutions with minimal energy input and allow the recovery of valuable metals. It relies on a semi-permeable membrane to allow the selective and spontaneous permeation of water from a low-concentration feed solution into a high-concentration draw solution. In this work, the results of the application of FO in the liquid mining of lithium from an emulated lithium brine lake using nontoxic aqueous inorganic draw solutions are reported. A flat-sheet cellulose triacetate membrane was used to study the effects of the type (NaCl, CaCl₂, and MgCl₂) and initial concentration (1.5, 2.5, and 3.5 M) of the draw solution on the final lithium concentration in the feed solution. The latter was found to increase by more than 3.5 times after 1 h, while MgCl₂ (3.5 M) as a draw solution showed the highest water flux (4 L/m²/h). Overall, our results indicate a strong potential for FO in liquid mining applications: the concentration of dilute aqueous solutions containing critical and strategic metals, which due to their low concentration cannot be recovered.