Pretreatment Strategies for Direct Lithium Extraction from Brines: A Systematic Review

This systematic review investigates pretreatment requirements for direct lithium extraction (DLE) technologies. Lithium (Li) is a critical mineral as defined by the United States Geological Survey due to its importance for battery electric vehicles and energy storage devices. Lithium-rich brines from many sources, including salt lakes, salars, oilfields, geothermal formations, seawater, and seawater reverse osmosis systems, are being evaluated for DLE to meet growing demand. These lithium-rich brines also contain high concentrations of other elements that may interfere with DLE processes through scale formation, chemical competition, or other mechanisms. Without pretreatment, DLE technologies currently under consideration may be less efficient than anticipated or even infeasible. This systematic review aggregates and analyzes information from previous studies on DLE pretreatment. Brine chemistry is summarized. Major and minor contaminating elements that may interfere with DLE are identified, along with gaps in literature related to trace elements. Pretreatment processes are discussed in the context of the brine type and composition, as well as the DLE technology to which they were applied. This review provides context into: the importance of pretreating for specific elements present in brine; the techniques used to pretreat for various confounding elements and brine conditions; and future areas of research that will aid in commercialization of DLE. This review provides timely information for addressing implementation challenges for full-scale development of lithium extraction from brines.