The raw material specialty of boron mineral

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Boron is a kind of typical non-metallic element. It is only existed in the compound form, but it is distributed in the dispersed state in the Earth’s crust, which is also a kind of element existed in the surface water, underground water, magmatic emanation, spring water and all gas liquid inclusion of the rock stratum.

Boron is also a kind of typical lithophile that is remarkably decentralized and widely distributed in different kinds of formation and types of rock.

Boron mineral can be formed almost in all the stages of geological cycle, in which it can form the industrial concentration by the effects of magmatism and hypergenesis as well as under the endogenous conditions and exogenous conditions.

Boron mineral is a kind of chemical raw materials mineral that is widely used. It is mainly used in producing borax, boric acid and element boron. It is also a necessary substance in glass, metallurgy, medicine, enamel, oil paint, daily chemical, agriculture, advanced industry of national defense and other departments. For example, the superfine boron powder can be used as effective catalyst for the explosive material. Therefore, the exploitation and utilization of boron resources will play more and more important role in the development of modern industry.

There are many boron-bearing minerals in the world. According to the chemical composition of boron-bearing minerals, they can be divided into three categories: boron silicate minerals, boron aluminum silicate minerals and borate minerals. Among them, boron silicate minerals mainly include datolite and danburite; boron aluminum silicate minerals mainly include tourmaline and axinite. In these two types of boron minerals, apart from the industrial value of datolite, the other minerals are not that useful as they are difficult to process or not gathered into a large number of industrial ore deposit. At present, borate minerals which is the third type of boron minerals, is mainly used as the raw materials of boron industry. There are more than 100 species of this kind of minerals, among which only above 10 kinds of minerals can be used on the exploitation and utilization of industrial boron resources, such as tinkal, suanite, szaibelyite, colemanite, sassolite, ulexite, pinnoite and so on. In china, szaibelyite, suanite, ludwigite, borax, ulexite, pinnoite and other minerals all can form medium and large size of deposits. Below is the introduction to the physical and chemical performance of several kinds of main borate minerals.

Szaibelyite (Mg2[B2O4(OH)](OH)): In which the theory content of B2O3 is 41.38 percents; it has the shape of fibrous, tabular and columnar crystal; and also has satin luster; in addition, its colors are white, grey and light yellow; its density is 2.62-2.75g/cm3 while the Moh’s hardness is 3-4, which is also insoluble in water.

Ludwigite ((Mg•Fe)3Fe[BO3]O2): In which the theory content of B2O3 is 17.83 percents; it has the forms of acicular, columnar, fibrous, short columnar-granular aggregate and other various crystalline form; and also has pearl and adamantine luster; its colors are black and black green; its density is 3.6-4.7 g/cm3; while the Moh’s hardness is 5.5-6; besides, it is insoluble in water.

Tinkal (Na2B4O5(OH)4•8H2O): In which the theory content of B2O3 is 36.51 percents; it has the forms of crystal or dense clumps and earthy aggregate; its colors are white, light grey and light yellow; its density is 1.69-1.72 g/cm3; while the Moh’s hardness is 2.0-2.5; besides, it is soluble in water.

Suanite (Mg2(B2O5): Its B2O3 theory content is 46.34 percents; it has the forms of tabular columnar, sphenoid, bamboo leaf shape, acicular, fibrous and other various crystalline forms; and also has glass oily luster; its colors are white and biscuit; its density is 2.91-2.93 g/cm3; while the Moh’s hardness is 5.9; besides, it is insoluble in water.

Ulexite (NaCa(H2O)6[B3B2O7(OH)4]): In which the B2O3 theory content is 42.95 percents; it has two kinds of crystalline forms which are fibrous and acicular aggregate; besides, it has vitreous and satin luster; and appears to be colorless or white; its density is 1.65-1.95 g/cm3; while the Moh’s hardness is 2.5; in addition, it is poorly soluble in water.

Colemanite (Ca(H2O)[B2BO4(OH)3]): In which the B2O3 theory content is 50.81 percents; it has the forms of equigranular, radiating and dense aggregate; also has vitreous and adamantine luster; it appears to be white or colorless; its density is 2.41-2.44 g/cm3; while the Moh’s hardness is 4.5-5; in addition, it is insoluble in water.

Pinnoite (Mg[B2O(OH)3]): Its B2O3 theory content is 42.46 percents; it has three kinds of crystalline forms which are columnar, short column and fibrous; it has vitreous luster; and appears to be white, light grey and colorless; its density is 2.3 g/cm3; while the Moh’s hardness is 3.5.