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Extraction

Lithium and its compounds were historically isolated and extracted from hard rock but by the 1990s mineral springs, brine pools, and brine deposits had become the dominant source. Most of these were in Chile, Argentina and Bolivia. Large lithium-clay deposits under development in the McDermitt caldera (Nevada, United States) require concentrated sulfuric acid to leach lithium from the clay ore.

By early 2021, much of the lithium mined globally comes from either " spodumene, the mineral contained in hard rocks found in places such as Australia and North Carolina" or from the salty brine pumped directly out of the ground, as it is in locations in Chile. In Chile's Salar de Atacama, the lithium concentration in the brine is raised by solar evaporation in a system of ponds. The enrichment by evaporation process may require up to one-and-a-half years, when the brine reaches a lithium content of 6%. The final processing in this example is done near the city of Antofagasta on the coast where pure lithium carbonate, lithium hydroxide, and lithium chloride are produced from the brine.

Low- cobalt cathodes for lithium batteries are expected to require lithium hydroxide rather than lithium carbonate as a feedstock, and this trend favors rock as a source.

One method for lithium extraction, as well as other valuable minerals, is to process geothermal brine water through an electrolytic cell, located within a membrane.

The use of electrodialysis and electrochemical intercalation has been proposed to extract lithium compounds from seawater (which contains lithium at 0.2 parts per million). Ion-selective cells within a membrane in principle could collect lithium either by use of electric field or a concentration difference. In 2024, a redox/electrodialysis system was claimed to offer enormous cost savings, shorter timelines, and less environmental damage than traditional evaporation-based systems.