Basic knowledge of bauxite

Bauxite Bauxite is actually a collective term for ores that can be used industrially and consists mainly of gibbsite, boehmite, or dicalite. Its application areas are both metallic and non-metallic.
Bauxite is the best raw material for the production of metallic aluminum, and it is also the most important application field. The amount of bauxite is more than 90% of the total output of bauxite in the world.
The non-metallic use of bauxite is mainly used as raw materials for refractory materials, abrasive materials, chemicals and high-alumina cement. The use of bauxite in non-metallic applications is small, but its use is quite extensive. For example, chemical products such as sulfate, trihydrate, and aluminum chloride can be used in papermaking, purified water, ceramics, and petroleum refining; activated alumina can be used as a catalyst and catalyst carrier in the chemical, oil refining, and pharmaceutical industries. Decolorization, dehydration, degassing, deacidification, drying and other physical adsorbents; aluminum chloride produced with r-Al2O3 can be used for organic synthesis applications such as dyes, rubber, medicine, petroleum; 3% to 5% of Al2O3 in glass composition Improve the melting point, viscosity, strength; abrasive material is the main raw material of high-grade grinding wheel and polishing powder; refractory material is an indispensable building material for the industrial sector.
Metal aluminum is the second most important metal in the world, second only to steel. In 1995, the world’s per capita consumption reached 3.29 kg. Because aluminum has a small specific gravity, good electrical and thermal conductivity, easy machining and many other excellent properties, it is widely used in various sectors of the national economy. At present, the largest amount of aluminum used in the world is the construction, transportation and packaging sector, accounting for more than 60% of the total aluminum consumption. Aluminum is an indispensable raw material for the electrical appliance industry, aircraft manufacturing industry, machinery industry and civilian appliances.
The focus is on the production of bauxite and its deposits. As for the use of bauxite as a refractory clay and its deposits, see Non-metallic minerals in "Refractory Clay" for discussion.
First, the characteristics of mineral raw materials Aluminum is one of the most widely distributed elements in the earth's crust. Aluminium is found in nature as oxides, hydroxides, and oxygen-containing aluminosilicates, and aluminum is rarely found in natural metals.
There are 258 kinds of aluminum-containing minerals known in nature, of which about 43 are common minerals. In fact, aluminum deposits made of pure minerals are not available and are generally 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. Due to the lack of bauxite resources, the former Soviet Union used nepheline and alum to refine alumina. China's sulphoaluminium antimony ore can comprehensively recover alumina.
The diaspore is also known as diaspore. Its structural formula and molecular formula are AlO(OH) and Al2O3·H2O, respectively. Orthorhombic system, crystallized well was columnar, plate-like, scaly, acicular, prismatic and so on. The diaspores in the ore generally contain different amounts of isomorphous contaminants such as TiO2, SiO2, Fe2O3, Ga2O3, Nb2O5, Ta2O5, and TR2O3. Diaspore is soluble in acid and alkali, but it dissolves very weakly under normal temperature and pressure. It needs to be completely decomposed under the conditions of high temperature, high pressure, and strong acid or 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 and so on.
The boehmite monohydrate is also known as boehmite and boehmite. Its structural formula is AlO(OH) and its molecular formula is Al2O3·H2O. Orthorhombic system, crystallized well was diamond, prismatic, prismatic, acicular, fibrous and hexagonal plate. The ore boehmite in the ore often contains Fe2O3, TiO2, Cr2O, Ga2O3, and the like. The boehmite is soluble in acid and alkali. This mineral is formed in an acidic medium and is mainly produced in a sedimentary bauxite ore, 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 alpha corundum, and hydration can become gibbsite.
The gibbsite is also known as hydrated bauxite, borosilicate, structural formula Al(OH), molecular formula is Al2O3·3H2O. Monoclinic crystals, crystallized in perfect hexagonal plate, prismatic, often fine crystal aggregates or twin crystals, gibbsite in the ore is mostly irregular aggregates, all contain different amounts of TiO2, SiO2 , Fe2O3, Nb2O5, Ta2O5, Ga2O3 and other isomorphous or mechanical inclusions. The gibbsite is soluble in acid and alkali, and the powder is heated to 100° C. and completely dissolved in 2 hours. The mineral is formed in an acidic medium, and gibbsite is a primary mineral in the weathering crust deposit, and is also a main ore mineral, which 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 bauxite is mainly Al2O3, SiO2, Fe2O3, TiO2, and H2O+. The total of these five components accounts for more than 95% of the composition, and is generally >98%. The minor components are S, CaO, MgO, K2O, Na2O, CO2, MnO2, organic matter, carbonaceous, etc., trace components include Ga, Ge, Nb, Ta, TR, Co, Zr, V, P, Cr, Ni, and the like. Al2O3 mainly occurs in aluminum minerals - diaspore, boehmite, and gibbsite, and secondly in silicon minerals (mainly kaolinite minerals).
Under endogenous conditions, Al2O3 and SiO2 due to the presence of silica