The chemical composition of bauxite is mainly Al2O3, SiO2, Fe2O3, TO2, accounting for about 95% of the total composition, and the secondary components are CaO, MgO, K2O, Na20, S, MnO2 organic matter and trace components Ga, Ge, etc.
Calcined bauxite for refractory material
The chemical composition of bauxite is mainly Al2O3, SiO2, Fe2O3, TO2, accounting for about 95% of the total composition.
Al2O2 is the main chemical component of bauxite, and its occurrence state is mainly aluminum hydroxide, by aluminosilicate, which is clay minerals; in addition, it can also contain a small amount or trace amount in iron and titanium minerals. SiO2- generally exists as clay minerals, and rarely is free stone molybdenum.
Fe2O2 generally exists in the form of hematite in karst or sedimentary bauxite: the primary zone is often pyrite, less siderite, oolitic mud, and rarely magnetite, etc.; Belt (late weathering) and red seven-type bauxite are mainly goethite, others such as water hematite, water goethite and aluminum goethite, aluminum hematite, etc.
Rare. In addition, a small amount of iron often exists in diaspore, boehmite, gibbsite and corundum in a similar form.
The content of TiO2 in bauxite is usually 2%~4%, but there are also higher, which can reach 6%~12%, such as bauxite in southwestern Sichuan and India.
Both titanium and aluminum are inert elements in the process of parent salt weathering, so A/Ti often maintains a constant ratio in each mining area. In bauxite, the independent minerals of T element are mainly anatase and rutile, by brookite, leucite and ilmenite. There are also similar occurrences in aluminum minerals. In addition, it also occurs in other minerals in the form of gels.
S is a very harmful impurity in bauxite, and it generally exists in the form of pyrite. The pyrite content is higher in the acoustic zone of sedimentary or karst bauxite; the sulfur content in the oxidation zone or accumulation bauxite is lower, generally between 0.05% and 0.1.
Physical and chemical indicators of calcined bauxite
Project |
Al2O3% |
Fe2O3% |
TiO2% |
CaO+MgO% |
K2O+Na2O% |
Bulk density(g/cm3) |
water absorption |
GL-90 |
≥89.5 |
≤1.5 |
≤4.0 |
≤0.35 |
≤0.35 |
≥3.35 |
≤2.5 |
GL-88A |
≥87.5 |
≤1.6 |
≤4.0 |
≤0.4 |
≤0.4 |
≥3.20 |
≤3.0 |
GL-88B |
≥87.5 |
≤2.0 |
≤4.0 |
≤0.4 |
≤0.4 |
≥3.25 |
≤3.0 |
GL-85A |
≥85 |
≤1.8 |
≤4.0 |
≤0.4 |
≤0.4 |
≥3.10 |
≤3.0 |
GL-85B |
≥85 |
≤2.0 |
≤4.5 |
≤0.4 |
≤0.4 |
≥2.90 |
≤5.0 |
GL-80 |
>80 |
≤2.0 |
≤4.0 |
≤0.5 |
≤0.5 |
≥2.90 |
≤5.0 |
GL-70 |
70~80 |
≤2.0 |
- |
≤0.6 |
≤0.6 |
≥2.75 |
≤5.0 |
GL-60 |
60~70 |
≤2.0 |
- |
≤0.6 |
≤0.6 |
≥2.65 |
≤5.0 |
GL-50 |
50~60 |
≤2.5 |
- |
≤0.6 |
≤0.6 |
≥2.55 |
≤5.0 |
The use of calcined bauxite:
(1) Aluminum smelting industry. For, aviation, automobiles, electrical appliances, chemicals, daily necessities, etc.
(2) Precision casting. The bauxite clinker is processed into fine powder to make a mold and then precision cast. For medical, aerospace, communications, instrumentation, machinery and medical equipment sectors.
(3) For refractory products. High alumina bauxite clinker has a refractoriness of up to 1780℃, strong chemical stability and good physical properties.
(4) Aluminum silicate refractory fiber. It has the advantages of light weight, high temperature resistance, good thermal stability, low thermal conductivity, small heat capacity and mechanical vibration resistance. For steel, non-ferrous metallurgy, electronics, petroleum, chemical, aerospace, atomic energy, and other industries. It is to put high-alumina clinker into a high-temperature electric arc furnace with a melting temperature of about 2000-2200 ° C, and after high-temperature melting, high-pressure high-speed air or steam injection, and cooling, it becomes white "cotton" - aluminum silicate refractory fiber. It can be pressed into fiber blanket, board or woven into cloth to replace refractory bricks lining high temperature furnaces in smelting, chemical, glass and other industries. Firefighters can use fire-resistant fiber cloth to make clothes.
(5) Using magnesia and bauxite clinker as raw materials, adding appropriate binder, it is very effective for pouring the overall lining of the ladle.
(6) Manufacture of various compounds of alumina cement, abrasive materials, ceramic industry and chemical industry that can make aluminum.
In recent years, bauxite powder and bauxite have been widely used in common cast steel coatings and cast iron coatings due to their high fire resistance, good chemical stability, small expansion coefficient, rich source and low price.
silicon mullite brick is a kind of refractory brick product made of super high alumina bauxite and silicon carbide as raw materials through a special sintering process. It has the characteristics of continuously forming a protective layer and reducing ring formation, and its heat resistance is also very good. The softening temperature under load can reach 1600 ℃, and the service life is long. Mainly used in the transition zone, decomposition zone and cooler of small and medium-sized cement kilns.
Silica brick is an acidic refractory mainly composed of tridymite, cristobalite and a small amount of residual quartz and glass phases
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High alumina brick is one of the indispensable basic refractory materials in the upper and middle parts of blast furnace body in iron and steel industry
Fireclay bricks are classified as weak acid refractories. Due to the large fluctuation range of chemical composition, different production methods, and differences in firing temperature, the properties of clay bricks change greatly.We can produce all kinds of Fireclay bricks according to customers' requirements
Calcined alumina is a product obtained by calcining aluminum hydroxide at high temperature to partially or almost completely convert it into aAl2O2.
Refractory carstables for ladles is made of high-purity fused corundum as the main material, high-purity spinel is added to the matrix, and an appropriate amount of binder and admixture (dispersant, water reducing agent) are added.