Brine mining is the extraction of useful materials (chemical elements or compounds) which are naturally dissolved in brine. The brine may be seawater, other surface water, groundwater, or hyper-saline solutions from several industries (e.g., textile industries). 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 common salt (NaCl), calcium, iodine, lithium, magnesium, potassium, bromine, and other materials, and are potentially important sources of a number of others. Brine mining supports waste minimization and resource recovery efforts.
History Around 500 BC, the ancient Chinese dug hundreds of brine wells, some of which were over 100 meters (330 feet) in depth. Large brine deposits under the earth's surface were drilled by drilling boreholes.Tom (1989), 103. Bamboo towers were erected, similar in style to modern-day oil derricks. Bamboo was used for ropes, casing, and derricks since it was salt resistant. Iron wedges were hung from a bamboo cable tool attached to a lever on a platform constructed atop the tower. The derricks required two to three men jumping on and off the lever that moved the iron wedge pounded into the ground to dig a hole deep enough into the ground to hit the brine.
Types of brines used for mineral extraction 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 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.
Saline lakes There are many saline lakes with salinity greater than seawater, making them appealing 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.
Shallow groundwater brines associated with saline or dry lakes
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 brines 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 (Wairakei, New Zealand, and Mammoth Lakes, California), and as a source of zinc (Salton Sea, California).W. L. Bourcier, M. Lin, and G. Nix, Recovery of Minerals and Metals from Geothermal Fluids, Lawrence Livermore National Laboratory, 8 September 2005 Boron was recovered circa 1900 from geothermal steam at Larderello, Italy. Lithium recovery has also been investigated.R. Gordon Bloomquist, "Economic benefits of mineral extraction from geothermal brines," 2006, Washington State University Extension Energy Program. But as of 2015, there is no sustained commercial-scale mineral recovery from geothermal brine.
Deep brines in sedimentary basins The concentration of dissolved solids in deep connate water varies from much less than seawater to ten times the total dissolved solids of seawater. In general, total dissolved solids (TDS) concentrations increase with depth. Most deep groundwaters classified as brines (having total dissolved solids equal to or greater than that of seawater) are predominantly sodium chloride type. However, the predominance of chloride usually increases with increasing TDS, at the expense of sulfate. The ratio of calcium to sodium usually increases with depth.Donald E. White, "Saline waters in sedimentary rocks", in Addison Young and John E. Galley (eds.), Fluids in Subsurface Environments, American Association of Petroleum Geologists, Memoir 4, 1965.
The presence of groundwater with TDS higher than seawater is in some cases due to contact with salt beds. More often, however, the higher TDS of deep sediments is thought to be the result of the sediments acting as semi-permeable membranes. As the sediments compact under burial pressure, the dissolved species are less mobile than the water, resulting in higher TDS concentrations than seawater. Bivalent species such as calcium (Ca+2) are less mobile than univalent species such as sodium (Na+), resulting in calcium enrichment. The ratio of potassium to sodium (K/Na) may increase or decrease with depth, thought to be the result of ion exchange with the sediments.
Industrial brine Several industries produce brines as by-products. Such industries are dairy, textile, leather, oil industries, etc. Thus, useful materials can be extracted and reused. However in industrial brine other chemicals and inhibitors might limit the ability to extract these useful materials.
Materials recovered from brines Many brines contain more than one recovered product. For instance, the shallow brine beneath Searles Lake, California, is or has been a source of borax, potash, bromine, lithium, phosphate, soda ash, and sodium sulfate.
Salt Source Salt concentration Seawater F. F. Wright, "Minerals of the ocean," in Frank E. Firth (ed.), The Encyclopedia of Marine Resources (New York: Van Nostrand, 1969) 406407.
Salt (sodium chloride) has been a valuable commodity since prehistoric times, and its extraction from seawater also goes back to prehistory. Salt is extracted from seawater in many countries around the world, but the majority of salt put on the market today is mined from solid evaporite deposits.
Salt is produced as a byproduct of potash extraction from Dead Sea brine at one plant in Israel (Dead Sea Works), and another in Jordan (Arab Salt Works). The total salt precipitated in solar evaporation at the Dead Sea plants is tens of millions of tons annually, but very little of the salt is marketed.
Today, salt from groundwater brines is generally a byproduct of the process of extracting other dissolved substances from brines and constitutes only a small part of world salt production. In the United States, salt is recovered from surface brine at the Great Salt Lake, Utah, and from a shallow subsurface brine at Searles Lake, California.
Sodium sulfate In 1997 about two-thirds of world sodium sulfate production was recovered from brine. Two plants in the US, at Searles Lake, California, and Seagraves, Texas, recovered sodium sulfate from shallow brines beneath dry lakes.
Soda ash Soda ash (sodium carbonate) is recovered from shallow subsurface brines at Searles Lake, California. Soda ash was formerly extracted at El Caracol, Ecatepec, in Mexico City, from the remnant of Lake Texcoco.
Colloidal silica Brines brought to the surface by geothermal energy production often contain concentrations of dissolved silica of about 500 parts per million. A number of geothermal plants have pilot-tested recovery of colloidal silica, including those at Wairakei, New Zealand, Mammoth Lakes, California, and the Salton Sea, California. To date, colloidal silica from brine has not achieved commercial production.
Potash Location Potassium concentration Source Ocean Seawater Ocean P. Evan Dresel and Athur W. Rose, Chemistry and Origin of Oil and Gas Well Brines in Western Pennsylvania, Pennsylvania Geological Survey, Open-File Report OFOG 10=01.0, 2010. Seawater, bittern remaining after salt precipitation Salar de Olaroz mine, Argentina Projects Olaroz, Orocobre website, accessed 17 March 2016. Shallow brine beneath dry lake Salar de Atacama, Chile Greta J. Orris, Deposit model for closed-basin potash-bearing brines, US Geological Survey, Open-File Report 2011-1283, 2011. Shallow brine beneath dry lake Da Chaidam Salt Lake, China Saline lake Dead Sea, Israel and Jordan Saline lake
Potash is recovered from surface brine of the Dead Sea, at plants in Israel and Jordan. In 2013 Dead Sea brine provided 9.2% of the world production of potash.Stephen M. Jasinski, "Potash," US Geological Survey, 2013 Minerals Yearbook, August 2015. As of 1996, the Dead Sea was estimated to contain 2.05 million tons of potassium chloride, the largest brine reserve of potassium other than the ocean.
Lithium
Location Lithium concentration Source Ocean 0.17 mg/L Seawater Clayton Valley, Nevada J. R. Davis and J. D. Vine, "Stratigraphic and tectonic setting of the lithium brine field, Clayton Valley, Nevada," in Basin and Range Symposium, Rocky Mountain Association of Geologists, Utah Geological Association, 1979. Shallow brine beneath dry lake Cornwall, United Kingdom Geothermal waters Paradox Basin, Utah Brine at depth (Cane Creek well) Salar de Olaroz mine, Argentina Shallow brine beneath dry lake Salton Sea, California Geothermal brine
In 2015 subsurface brines yielded about half of the world's lithium production. Whereas seawater contains about , subsurface brines may contain up to , more than four orders of magnitude greater than seawater. Typical commercial lithium concentrations are between 200 and .
The largest operations are in the shallow brine beneath the Salar de Atacama dry lakebed in Chile, which as of 2015 yielded about a third of the world's supply. The brine operations are primarily for potassium; extraction of lithium as a byproduct began in 1997.US Geological Survey, Lithium, Mineral Commodity Summary, 2016.
The shallow brine beneath the Salar de Uyuni in Bolivia is thought to contain the world's largest lithium resource, often estimated to be half or more of the world's resource. As of 2015, no commercial extraction has taken place, other than a pilot plant.
Commercial deposits of shallow lithium brines beneath dry lakebeds have the following characteristics in common:Dwight Bradley and others, "A preliminary deposit model for lithium brines," US Geological Survey, Open-File Report 20131006, 2013.
Arid climate Closed basin with a dry or seasonal lake Tectonically driven subsidence Igneous or geothermal activity Lithium-rich source rock Permeable aquifers Enough time to concentrate brine
In 2010 Simbol Materials received a $3 million grant from the U.S. Department of Energy for a pilot project aimed at showing the financial feasibility of extracting high-quality lithium from geothermal brine. It uses brine from the 49.9 megawatt Featherstone geothermal power plant in California's Imperial Valley. Simbol passes the plant's extracted fluid through a series of membranes, filters and adsorption materials to extract lithium.
In 2016, MGX Minerals developed a proprietary design process (U.S. Provisional Patent #62/419,011) to potentially recover lithium and other valuable minerals from highly mineralized oilfield brine. The company has acquired development rights to over approximately 1.7 million acres of brine-bearing formations in Canada and Utah. According to MGX, the Saskatchewan Research Council, an independent laboratory, verified the MGX Minerals petrolithium extraction technology in April 2017.Rockstone Research (https://www.rockstone-research.com/images/PDF/MGX20en.pdf