Underground brines

V. M. G. Mannar and H. L. Bradley, Guidelines for the Establishment on Solar Salt Facilities from Seawater, Underground Brines and Salted Takes, United Nations Industrial Development Organi2ation, 1983. 

In the United States the primary route for making calcium chloride is by the evaporation of underground brines (see Chemicals frombrines). Additional commercial material is available by the action of hydrochloric acid on limestone. Typically the hydrochloric acid is a by-product of some other commercial process and the conversion to calcium chloride is motivated by waste avoidance (see Hydrogen chloride). 

A third source of brine is found underground. Underground brines ate primarily the result of ancient terminal lakes that have dried up and left brine entrained in their salt beds. These deposits may be completely underground or start at the surface. Some of these beds ate hundreds of meters thick. The salt bed at the Salat de Atacama in Chile is over 300 m thick. Its bed is impregnated with brine that is being pumped to solar ponds and serves as feedstock to produce lithium chloride, potassium chloride, and magnesium chloride. Seades Lake in California is a similar ancient terminal lake. Brine from its deposit is processed to recover soda ash, borax, sodium sulfate, potassium chloride, and potassium sulfate. 

Occurrence. Bromine [7726-95-6] is found in seawater and in underground brine deposits of marine origin (21). Bromine (qv) is also found in Dead Sea brine and is currently being produced there by the Dead Sea Works. 

Occurrence. Iodine [7553-56-2] is widely distributed in the Hthosphere at low concentrations (about 0.3 ppm) (32). It is present in seawater at a concentration of 0.05 ppm (33). Certain marine plants concentrate iodine to higher levels than occur in the sea brine these plants have been used for their iodine content. A significant source of iodine is caUche deposits of the Atacama Desert, Chile. About 40% of the free world s iodine was produced in Japan from natural gas wells (34), but production from Atacama Desert caUche deposits is relatively inexpensive and on the increase. By 1992, Chile was the primary world producer. In the United States, underground brine is the sole commercial source of iodine (35). Such brine can be found in the northern Oklahoma oil fields originating in the Mississippian geological system (see Iodine and iodine compounds). 

Later, more concentrated brines of the Midland, Michigan producers displaced the California producers. In 1976, Houston Chemicals began recovery using the blowing-out process from underground brines of the Anadarko Basin in northwestern Oklahoma. Annual capacity was 900 metric tons (38). In 1991, nearly all of the iodine produced was made from Oklahoma brines by a blowing-out process. 

Calcium chloride is obtained as a by-product in the manufacture of sodium carbonate (soda ash) by ammonia-soda (Solvay) process. The process involves the reaction of sodium chloride with calcium carbonate and ammonia. Calcium chloride is currently produced in bulk amounts by evaporation of natural underground brines. In the laboratory, calcium chloride can be prepared by treating bmestone with hydrochloric acid followed by evaporation of solution to obtain crystals. The crystals are dehydrated to obtain anhydrous salt. Calcium oxide or hydroxide may be used instead of carbonate. 

Iodine is widely distributed in nature, found in rocks, soils and underground brines. An important mineral is lautarite, which is anhydrous calcium iodate found in nitrate deposits in Chde. The element also occurs in brown seaweeds, in seawater, and in many natural gas wells. Its concentration in the earth s crust is an estimated 0.5 mg/kg and in seawater 0.06 mg/L. 

All the magnesium produced in the world currently is derived from its minerals dolomite and carnallite, as well as from the underground brines and seawaters. In most processes, magnesium is recovered from its mineral or brine either as magnesium chloride or converted to the latter for electrolytic production. 

In most commercial processes, the compound is either derived from the sea water or from the natural brines, both of which are rich sources of magnesium chloride. In the sea water process, the water is treated with lime or calcined dolomite (dolime), CaO MgO or caustic soda to precipitate magnesium hydroxide. The latter is then neutralized with hydrochloric acid. Excess calcium is separated by treatment with sulfuric acid to yield insoluble calcium sulfate. When produced from underground brine, brine is first filtered to remove insoluble materials. The filtrate is then partially evaporated by solar radiation to enhance the concentration of MgCb. Sodium chloride and other salts in the brine concentrate are removed by fractional crystallization. 

In the United Stales the principal route for making calcium chloride is by the evaporation of underground brines. Additional commercial material is available by the action of hydrochloric acid on limestone. 

Major sources of commercial bromine are underground brines in Arkansas (which contain 3000-5000 ppm bromine), China, Russia, and the United Kingdom. Bitterns from mined potash in France and Germany, seawater bitterns in India, Italy, and Japan, and bitterns of potash production (which contain 12,000 ppm bromine) from Dead Sea brines in Israel are the other sources. 

Another method for recovering strontium from NaCI stripping concentrates as well as from natural underground brines of similar composition has been examined in the laboratory of Professor V. I. Gorshkov at Moscow State University [254-256]. 

Bondarenko, S. S., Lubensky, A. A. and Kulikov, G. V. Geologiko-Economi-cal Estimation of Underground Brine Resources, Nedra, Moscow, 1988, p. 203. (Russian)... 

Equations 1.30 and 1.31 work pretty well for single electrolyte aqueous solutions but cannot be easily used when two or more electrolytes have high concentrations. In a multicomponent aqueous solution, Equations 1.30 and 1.31 can be used only if one of the electrolytes is dominating and concentrations of all others are much smaller. A well-known example of such a solution is sea water (or underground brine) where... 

Once made, chlorine can be used to produce bromine and iodine from seawater, or underground brines like those found in Louisiana. Chlorine is bubbled through the solution to yield the free elements ... 

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