Brine mining
Brine mining is the extraction of valuable minerals and elements from concentrated saline solutions known as brines, which occur naturally in geological formations such as salt flats, geothermal reservoirs, or as byproducts from desalination and oil production processes.[1][2] This method, a form of solution mining, targets soluble resources like lithium, potassium, magnesium, and sodium chloride by dissolving and recovering them from subsurface deposits or surface pools.[3] Unlike traditional hard-rock mining, brine mining leverages the natural solubility of these minerals in water, making it particularly suitable for arid regions where evaporation can concentrate the solutions efficiently.[4] The process typically begins with drilling wells to pump brine to the surface, followed by concentration through solar evaporation in large, shallow ponds that can span kilometers.[4] Over periods of 12 to 24 months, water evaporates under the sun, precipitating less soluble salts first (such as sodium chloride) while enriching the remaining solution with target minerals like lithium, which reaches concentrations of up to 5,000 ppm.[1][4] The concentrated brine is then treated chemically—often with soda ash to form lithium carbonate—or via emerging technologies like direct lithium extraction (DLE) using adsorption or ion exchange to accelerate recovery, reduce evaporation times, and minimize environmental impacts; several DLE projects reached commercial scale by 2025.[1][3][5] Brine mining supplies approximately 30% of the world's lithium as of 2024, the most economically significant mineral extracted this way, with major deposits in the Lithium Triangle of South America's Andes region, including Chile's Salar de Atacama (average lithium concentration of 1,400 mg/L) and Bolivia's Salar de Uyuni, the largest salt flat on Earth.[6] Other notable sites include Clayton Valley in Nevada, USA, and geothermal brines in California's Imperial Valley, where operations yield substantial sodium, potassium, and calcium chlorides annually.[4][3] Rising global demand for lithium in batteries as of 2025 has spurred innovations, including recovery from produced water in oil fields and desalination waste, positioning brine mining as a key contributor to sustainable critical mineral supply chains.[1]Overview
Definition and Basic Process
Brine mining refers to the extraction of valuable chemical elements or compounds that are naturally dissolved in brine, defined as a concentrated aqueous solution of salts, typically containing high levels of sodium chloride along with other dissolved minerals.[7] This process targets resources such as lithium, potassium, magnesium, and bromine, which are recovered from natural saline waters rather than solid ores.[8] The basic workflow of brine mining begins with the pumping or collection of brine from subsurface reservoirs, surface salt lakes, or associated industrial streams. The brine is then concentrated, often through solar evaporation in shallow ponds that allow water to evaporate under arid conditions, leaving behind increasingly saturated solutions and initial precipitates of less soluble salts. Target minerals are subsequently separated via methods like selective precipitation, where chemical agents induce the formation of solid compounds, or through filtration and purification steps. Finally, the isolated minerals undergo further refining—such as calcination or chemical conversion—to yield commercial products like lithium carbonate, potassium chloride (potash), or bromine compounds.[9] Unlike hard-rock mining, which involves energy-intensive crushing and grinding of solid ores to liberate minerals, brine mining leverages the pre-dissolved state of target elements, reducing mechanical processing needs but often requiring extensive land and time for evaporation, alongside considerations for water management due to the large volumes of saline fluid handled.[10] Brine mining supplied about 54% of global lithium production in 2024, a critical input for batteries and electronics, as well as nearly all commercial bromine—used in flame retardants and pharmaceuticals—and a significant share of potash, essential for fertilizers.[5][11][12] A general schematic of the brine mining flow includes:- Extraction: Brine is pumped to the surface.
- Concentration: Evaporation reduces volume and precipitates impurities.
- Separation: Target ions are isolated via precipitation or adsorption.
- Processing: Refined products are dried, crystallized, or converted for market use. This sequence minimizes waste while maximizing recovery efficiency in suitable environments.[13]