Boron minerals

The element is not found free in nature, but occurs as orthoboric acid usually found in certain volcanic spring waters and as borates in boron and colemantie. Ulexite, another boron mineral, is interesting as it is nature s own version of "fiber optics."... 

Etibank is the sole producer of boron minerals and derivatives in Turkey, which is second in production only to the United States. The open-pit Kirka mine in the Eskisehir Province is the only source of Turkish sodium borate ore. A tincal concentrate is produced from ore that has been blasted and carried in tmcks to the concentration plant. The ore is screened and cmshed to reduce it to —100 mm and then hammer milled to —25 mm. The stockpiled material is further milled and screened to 6 mm. A fraction of +1 mm (+18 mesh, U.S. Standard) is washed and classified to remove fine clay. Clay is removed from the —1 mm faction bypassing it through cyclones and then through a classifier. This material is centrifuged and combined with the washed + 1 mm faction to produce a final product which is a —6 mm concentrate having 6—8 wt % moisture and 32% 2 3 1987 production was... 

R. WiH, Y. Sakuma, and R. WiUhalm, "Boron Minerals and Chemicals Report," in Chemical Economics Handbook, SRI International, Menlo Park, Calif., Sept. 1990, p. 717.1000A. 

O Neil JR (1986) Theoretical and experimental aspects of isotopic fractionation. Rev Mineral 16 1-40 Oi T (2000) Calculations of reduced partition function ratios of monomeric and dimeric boric acids and borates by the ab initio molecular orbital theory. J Nuclear Sci Tech 37 166-172 Oi T, Nomura M, Musashi M, Ossaka T, Okamoto M, Kakihana H (1989) Boron isotopic composition of some boron minerals. Geochim Cosmochim Acta 53 3189-3195 Oi T, Yanase S (2001) Calculations of reduced partition function ratios of hydrated monoborate anion by the ab initio molecular orbital theory. J Nuclear Sci Tech 38 429-432 Paneth P (2003) Chlorine kinetic isotope effects on enzymatic dehalogenations. Accounts Chem Res 36 120-126... 

The second main ingredient in reinforced plastic is the reinforcement, eg, fibers of glass, carbon, boron, mineral, cellulose, or polymers. Reinforcements can be configured in many ways, such as continuous or chopped strands, milled fibers, rovings, tows, mats, braids, and woven fabrics. 

Boric oxides, boric acids, and metal borates are of primary importance in any discnssion of boron chemistry since these inclnde essentially all boron minerals and the vast majority of boron componnds prodnced and nsed worldwide on a weight basis. Reviews of this chemistry and the commercial aspects of this general snbject are available. hs... 

Four sodium tetraborates are important as boron minerals and/or large tonnage items of commerce. Borax, or sodium tetraborate decahydrate, is extracted from large open-pit mines in Tnrkey and the United States. Turkish beneficiated native borax, also referred to by the mineral name tincal, is used directly in glass making and other applications. Refined borax is used widely in consumer products and as... 

Sodium borate minerals are found in nature mainly as Na2B407 IOH2O (tincal, raw borax), the most important boron mineral, Na2B407 4H2O (kemite, rasorite),... 

Sand, preferably fine particulate, is used as the source of Si02 in the manufacture of silicate glasses. Raw materials for the standard network-modifiers are lime, dolomite (CaC03 MgC03) for the alkaline earth oxides, sodium carbonate for sodium oxide, feldspar (sodium potassium calcium aluminum silicate), or other naturally occurring aluminum silicates, for aluminum oxide. Boron is used in the form of boric acid, borax and other boron minerals, e.g. ulexite (NaCa[B505(0H)6] 5H2O) or colemanite... 

Raw materials for glass wool sand, lime, dolomite, feldspar, kaolin, alumina-containing igneous rock, sodium carbonate, sodium sulfate, potassium carbonate, boron minerals... 

The soil forming rocks in this region are soft Tertiary and Quaternary sedimentary rocks, very often salty, with carbonate, and predominantly heavy granulometric composition (clay and loam-mergel depositions). The micas are responsible for the main part of boron in clay, sandstone and sand and the boron minerals represent the minor part (Table 12). 

Celik, M.S. and Yasar, E., Electrokinetic properties of some hydrated boron minerals, 7. Colloid Interf. Sci., 173, 181, 1995. 

The most abundant boron mineral is tourmaline, a complex aluminosilicate containing about 10% of boron. The principal boron ores are borates, such as borax, Na2B405(0H)4-8H2O, which occur in large beds in arid parts of California and elsewhere. 

The Raman spectrum of the aqueous borate ion and x-ray studies on boron minerals have shown that the borate ion has tetrahedral symmetry and is, in all likelihood, B(OH)4 , In 3 Af sodium perchlorate solution at 25° and with a total concentration of boron of B <0.025 M, essentially the mononuclear species boric acid, B(OH)s, and the anion B(OH)4 seem to be present, whilst, for B> 0.025 M, two polynuclear species, B30s(0H)4 and B308(0H)5 , can also be detected. This means that boric acid does not act as a proton donor but as a Lewis acid, accepting the electron pair of the base (for example, OH ) to form the tetrahedral anion B(OH)4 . 

Anovitz LM, Hemingway BS (1996) Thermodynamics of boron minerals Summary of stractuial, volumetric and thermochemical data. Rev Mineral 33 181-261... 

Boron — (Ar. Buraq, Pers. Burah), B at. wt. 10.811(7) at. no. 5 m.p. 2075°C b.p. 4000°C sp. gr. of crystals 2.34, of amorphous variety 2.37 valence 3. Boron compounds have been known for thousands of years, but the element was not discovered until 1808 by Sir Humphry Davy and by Gay-Lussac and Thenard. The element is not found free in nature, but occurs as orthoboric acid usually in certain volcanic spring waters and as borates in borax and colemanite. Ulexite, another boron mineral, is interesting as it is nature s own version of fiber optics. Important sources of boron are the ores rasorite (kern-ite) and tincal (borax ore). Both of these ores are found in the Mojave Desert. Tincal is the most important source of boron from the Mojave. Extensive borax deposits are also found in Turkey. Boron exists naturally as 19.9% B isotope and 80.1% B isotope. Ten other isotopes of boron are known. High-purity crystalline boron may be prepared by the vapor phase reduction of boron trichloride or tribromide with hydrogen on... 

Boron is distributed widely in the environment. Naturally, elevated boron levels are usually associated with marine sediments, thermal springs, large deposits of boron minerals, seawater, and certain groundwaters. Human activities, however, have resulted in elevated boron concentrations near coal-bred plants, in mine drainage waters, in muiucipal wastes, and... 

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