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Brine mining


Brine mining is the extraction of useful materials (elements or compounds) which are naturally dissolved in brine. The brine may be seawater, other surface water, or groundwater. It differs from solution mining or in-situ leaching in that those methods inject water or chemicals to dissolve materials which are in a solid state; in brine mining, the materials are already dissolved.

Brines are important sources of salt, iodine, lithium, magnesium, potassium, bromine, and other materials, and potentially important sources of a number of others.

Commercial brines include both surface water (seawater and saline lakes) and groundwater (shallow brine beneath saline or dry lakes, and deep brines in sedimentary basins). Brine brought to the surface by geothermal energy wells often contains high concentrations of minerals, but is not currently used for commercial mineral extraction. .

Seawater has been used as a source of sea salt since prehistoric times, and more recently of magnesium and bromine. Potassium is sometimes recovered from the bittern left after salt precipitation. The oceans are often described as an inexhaustible resource.

There are many saline lakes with salinity greater than seawater, making them attractive for mineral extraction. Examples are the Dead Sea and the Great Salt Lake. In addition, some saline lakes, such as Lake Natron in East Africa, have chemistry very different than seawater, making them potential sources of sodium carbonate.

The groundwater beneath saline or dry lakes often has brines with chemistry similar to that of the lakes or former lakes.

The chemistry of shallow brines used for mineral extraction is sometimes influenced by geothermal waters. This is true of a number of shallow brines in the western United States, such as at Searles Lake, California.

Geothermal power plants often bring brine to the surface as part of the operation. This brine is usually re-injected into the ground, but some experiments have been made to extract minerals before re-injection. Brine brought to the surface by geothermal energy plants has been used in pilot plants as a source of colloidal silica (Wairkei, New Zealand, and Mammoth Lakes, California), and as a source of zinc (Salton Sea, California). Boron was recovered circa 1900 from geothermal steam at Larderello, Italy. Lithium recovery has also been investigated. But as of 2015, there is no sustained commercial-scale mineral recovery from geothermal brine.


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