The density of aluminum industry and the density of structural aluminum is 2.7, which is about 1/3 of that of general metals, and the conductivity of commonly used aluminum wires is about 61% of copper, and the thermal conductivity is half of silver. Although pure aluminum is extremely soft and ductile, it can still be hardened by cold working and alloying. Bauxite is an important source of aluminum. It takes about two pounds of bauxite to make one pound of alumina, and two pounds of aluminum oxide to make one pound of metallic aluminum.
Aluminum exists in nature as oxides, hydroxides and oxygen-containing aluminosilicates. Natural metals in which aluminum is rarely found. There are currently 258 known aluminum-bearing 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 technological point of view, not all aluminum-bearing minerals can become industrial raw materials. Bauxite composed of diaspore, boehmite or gibbsite is mainly used for refining metallic aluminum.
Diaspore is also known as diaspore. Its structural formula and molecular formula are AlOOH and Al2O3? H2O orthorhombic crystal system. The crystals intact are columnar, plate-like, scale-like, needle-like and prismatic. The diaspore in the ore generally contains TiO2SiO2Fe2O3Ga2O3Nb2O5Ta2O5P2O3 and other similar quantities of the same kind of mixed materials. Diaspore is soluble in acids and alkalis, but it dissolves very weakly at room temperature and pressure, and can only be completely decomposed under high temperature and pressure and strong acid or alkali concentration. Diaspore is formed in an acidic medium and coexists with boehmite, hematite, goethite, kaolinite, chlorite, pyrite, etc. Its hydration can become gibbsite, dehydration can become α corundum, can be explained by kaolinite, pyrite, siderite, chlorite and so on.
Boehmite monohydrate is also known as boehmite and boehmite. Its structural formula is AlOOH and its molecular formula is Al2O3? H2O rhombic crystal system. shape. The boehmite in the ore often contains Fe2O3TiO2Cr2OGa2O3 and the like. Boehmite monohydrate is soluble in acids and alkalis. The mineral is formed in an acidic medium and is mainly produced in accumulated bauxite, which is characterized by symbiosis with siderite. It can be explained by diaspore, gibbsite, kaolinite, etc., dehydration can be transformed into diaspore and alpha corundum, hydration can be turned into gibbsite.
Gibbsite, also known as gibbsite and diaspore, has a structural formula of AlOH with the molecular formula of Al2O3? 3H2O monoclinic system. The crystals intact are in the shape of hexagonal plates and prisms, and often have fine crystal aggregates or twin crystal The gibbsite in the ore is mostly in the form of irregular aggregates, all containing different amounts of TiO2SiO2Fe2O3Nb2O5Ta2O5Ga2O3 and other similar homogeneous or mechanical admixtures. The gibbsite is soluble in acid and alkali, and its powder can be completely dissolved after heating to 100 ℃ for 2h. Gibbsite is formed in an acidic medium and is a primary mineral in a weathered shell deposit, and it coexists with kaolinite, goethite, hematite, and illite. The dehydration of gibbsite can be transformed into boehmite, diaspore and α-corundum, which can be explained by kaolinite, halloysite and so on.