The chemical formula of dolomite: [CaMg(CO3)2], also known as dolomite, dolomite accounts for about 2% of the earth’s crust. Dolomite deposits are relatively common around the world and are mostly sedimentary rocks or equivalents that change structure.
Dolomite is one of the widely distributed minerals in sedimentary rocks, which can form very thick dolomite. The primary sedimentary dolomite is directly formed in the sea lake with high salinity, and a large amount of dolomite is secondary, which is formed by the metasomatism of limestone by magnesium-containing solution. Marine sedimentary dolomite is often interbedded with siderite and limestone layers. In lake sediments, dolomite coexists with gypsum, anhydrite, halite, and potash.
Pure dolomite is a kind of mineral composed of calcium carbonate and magnesium carbonate. The theoretical ratio of calcium carbonate and magnesium carbonate is roughly 1: 1. It contains 30.41% calcium oxide, 21.86% magnesium oxide, 47.73% carbon dioxide, and often contains SiO2. AL2O3. Fe2O3, etc. impurities.
Generally white, off-white, relative density 2829, Mohs hardness 3.4-4.4, specific gravity 2.85-2.9, with vitreous luster, insoluble in water, slow reaction with dilute acid, only foaming slowly in powder or heated state. Widely distributed in nature. Dolomite is a carbonate mineral, there are iron dolomite and manganese dolomite respectively. The color of dolomite is generally grayish-white, and it is similar to limestone in appearance. Commonly called dolomite refers to purer dolomite with a calcite content of less than 5%. It can be used in building materials, ceramics, glass and refractory materials, chemical industry, agriculture, environmental protection, energy saving and other fields.
Application of dolomite in various fields:
1.1 Metallurgical Industry
Magnesium has good thermal conductivity, non-magnetic, non-toxic metal, magnesium alloy has the characteristics of light weight, durability, high strength, high toughness, good mechanical properties, etc. . in the magnesium smelting industry. Dolomite is one of the important raw materials for the production of magnesium metal, and the silicothermic method is generally used in the extraction of metal magnesium. The output accounts for about 20% of the total metal magnesium, and the right67. The silicothermal method is to calcine and decompose dolomite to obtain a mixture of MgO and CaO. After the calcined powder is milled and sieved, the molar ratio of Mg and Si is 2:1, and an appropriate amount of fluorite is added as a catalyst. spheres, reduced with silicon at 1150-1200C to form calcium and magnesium silicates. Dolomite is an important auxiliary material for steelmaking and sintering in the metallurgical industry. It is used as a flux in the ironmaking process. It has better fluidity than pure limestone slag and has a good desulfurization effect, thereby improving the quality of pig iron. It is used in steelmaking. , has the advantages of fast slag removal and so on. Dolomite is used as a refractory material to prepare refractory bricks, which are mainly used for steelmaking converter linings and open hearth furnace walls, and secondly for refining devices outside the furnace.
1.2 Building materials industry
As the raw material of magnesia cementitious material: dolomite is calcined at a certain temperature. The dolomite is partially decomposed to form magnesium oxide and calcium carbonate, and then the magnesium oxide solution and aggregate are added to stir and form. After curing, a high-strength ammonia oxy-iron cement material is formed. The 8th generation commitment period has broad application prospects in the development of Xinfajian village structures. Dolomite accounts for about 15% of the float glass mixture, and dolomite introduces two main components CaO and MgO, MgO can reduce the crystallization tendency of glass. In the production of ceramics, dolomite can reduce the firing temperature of the green body, promote the dissolution of quartz and the formation of dolomite, and increase the transparency of the green body, which can be used to produce Glass ceramics.
1.3 Chemical Industry
In the chemical industry, Zimite is mainly used to produce magnesium-containing compounds, and it is also the best way to increase the added value of Zimite products. At present, the main chemical products that have been industrialized are magnesium oxide, light magnesium carbonate, magnesium hydroxide, and Various magnesium salt products. Light magnesium carbonate, also known as industrial hydrated basic magnesium carbonate or basic magnesium carbonate, the molecular formula can be expressed as xMgCO3 yMg(OH)2 zHO. White monoclinic crystal or amorphous powder, non-toxic, tasteless, relative density 2.16, in air medium stable. Slightly soluble in water, the aqueous solution is weakly alkaline. Soluble in acid and ammonium salt solution, react with acid to form magnesium salt and release carbon dioxide. High temperature pyrolysis into magnesium oxide.
Light magnesium carbonate is a basic inorganic chemical raw material, mainly used in the manufacture of magnesium salts, magnesium oxide, magnesium metal, fireproof materials, printing inks, ceramics, household chemicals, fillers and reinforcing agents for rubber products: it can also be used in shipbuilding, Boiler, steelmaking, glass, pigment, medicine and other industries. Food grade light magnesium carbonate is used as food additive and improver. The main use of light magnesium carbonate is as an industrial intermediate raw material, such as the preparation of high-purity magnesia or magnesia.