[China Aluminum Industry Network] Aluminum is a light metal. Its compounds are widely distributed in nature. Aluminum is second only to oxygen and silicon in the earth's crust. Among the metal species, aluminum is second only to steel and is the second largest metal. Aluminum has special chemical and physical properties. Nowadays one of the more commonly used industrial metals is not only lighter in weight and firmer in texture, but also has good ductility, electrical conductivity, thermal conductivity, heat resistance and nuclear radiation resistance, and the development of the national economy. The important basic raw materials.
Aluminum density and structural aluminum density is 2.7 is about 1/3 of the general metal and commonly used aluminum wire conductivity is about 61% copper, thermal conductivity is half of silver. Although pure aluminum is extremely soft and ductile, it can be hardened by cold working and alloying. Bauxite is an important source of aluminum. It takes about two pounds of bauxite to produce one pound of alumina and two pounds of alumina to make one pound of metal aluminum.
Aluminium is naturally found in natural metals where oxides, hydroxides, and oxygen-containing aluminosilicates are rarely present. At present, there are 258 kinds of aluminum-containing minerals, of which about 43 are rare minerals. In fact, aluminum deposits composed of pure minerals are generally not symbiotic and mixed with impurities. From an economic and technical point of view, not all aluminum-containing minerals can be used as industrial raw materials. The metal used to extract the aluminum is mainly bauxite consisting of diaspore, boehmite or gibbsite.
The diaspore, also known as diaspore, structural formula and molecular formula are AlOOH and Al2O3? H2O orthorhombic system, crystallized well was columnar, plate-like, scaly, acicular, prismatic and so on. The diaspores in the ore generally contain TiO2SiO2Fe2O3Ga2O3Nb2O5Ta2O5P2O3 and other heterogeneous isomorphs. Diaspore is soluble in acid and alkali, but it dissolves very weakly under normal temperature and pressure. It needs to be completely decomposed under high temperature and high pressure and strong acid or strong alkali concentration. Diaspore is formed in an acidic medium and is symbiotic with boehmite, hematite, goethite, kaolinite, chlorite, and pyrite. Its hydration can become gibbsite, dehydration can become α corundum, can be kaolinite, pyrite, siderite, chlorite, etc.
Boehmite is also known as boehmite and boehmite. Its structural formula is AlOOH. Its molecular formula is Al2O3?H2O orthorhombic. Its crystallized form is rhombohedral, prismatic, prismatic, acicular, fibrous and hexagonal. shape. The ore boehmite in the ore usually contains isomorphous Fe2O3TiO2Cr2OGa2O3. The boehmite is soluble in acid and alkali. The mineral is formed in an acidic medium and is mainly produced in a heaped bauxite mine, which is characterized by its symbiotic association with siderite. It can be represented by diaspore, gibbsite, kaolinite, etc. Dehydration can be converted into diaspore and α corundum, and hydration can become gibbsite.
Also known as gibbsite, hydrated aluminoxite, borosilicate, structural AlOH molecular formula is Al2O3? 3H2O monoclinic system, crystallized in perfect hexagonal plate, prismatic, often with fine crystalline aggregates or double crystals Most of the gibbsite in the ore is irregular aggregates, all containing different amounts of TiO2SiO2Fe2O3Nb2O5Ta2O5Ga2O3 or other similar material or mechanical incorporation. The gibbsite is soluble in acid and alkali, and its powder is heated to 100° C. and completely dissolved in 2 hours. Gibbsite is formed in an acidic medium and is a primary mineral in weathering crust deposits. It is symbiotic with kaolinite, goethite, hematite, and illite. The dehydration of gibbsite can be converted into boehmite, diaspore and α-corundum, which can be accounted for by kaolinite, halloysite, and the like.
The chemical composition of the aluminum bauxite is mainly composed of Al2O3SiO2Fe2O3TiO2H2O+ which accounts for more than 95% of the total composition. In general, >98% of the main components are SCaOMgOK2ONa2OCO2MnO2 organic matter, carbonaceous, etc., and trace elements include GaGeNbTaPCoZrVPCrNi. Al2O3 mainly occurs in the aluminum minerals-dipramite, boehmite, and gibbsite, and secondly in the silicon minerals (mainly kaolinite minerals).
Under endogenous conditions, due to the presence of silica, Al2O3 and SiO2 are often tightly combined to form aluminosilicate minerals. These minerals generally have a Al-Si ratio of less than 1 and the industry generally requires Al2O3 ≥ 40% Al/Si for aluminum ore. >1.82.6 Therefore, industrial aluminum deposits are rarely formed under endogenous conditions.
At present, the known industrial bauxite mines at home and abroad are mostly under the supergene conditions formed under supergene conditions. There are two main forms of bauxite formation: weathering-residual (I) mineralization (red earth mineralization) and weathering. - Handling - accumulating mineralization or weathering - transformation - redeposition mineralization (accumulation mineralization) Weathering-residual (remaining) mineralization is the beneficial terrain (such as residual mounds) where aluminum-containing parent rocks are well excreted under hot and humid climate conditions. Because of the weathering and decomposition of water, CO2, and biomass, KNaCaMg and SiO2, which are easily soluble substances in the parent rock, are lost and lost. AlFeTi, a less active material, forms lateritic bauxite in situ. Weathering-conveying-accumulating mineralization is the weathering, erosion, or mechanical, or chemical weathering of aluminum-containing rocks, lateritic weathered crusts or formed laterite deposits, gravity, water and natural acids (sulfuric acid, carbonic acid, organic acids). The physical and chemical transformation functions such as transportation are used to form bauxite deposits in hilly depressions, valleys, offshore lake basins or coastal lakes, and in confined basins, and deposits of bauxite are formed in the water medium environment.
