Bauxite minerals

L. H. Baumgardner, Bauxite, Mineral Commodity Summaries, U.S. Bureau of Mines, Washington, D.C., 1990. 

Beach JR, de Klerk NH, Fritschi L, et al Respiratory symptoms and lung function in bauxite miners. Int Arch Occup Environ Health 74(7) 489 94, 2001... 

Bauxite mineral matter used as a treating agent hydrated aluminum oxide formed by the chemical weathering of igneous rocks. 

The most widespread fill material is reddish brown (2.5 YR 4/4, 5 YR 4/4) loam with a minor admixture of relatively large oolitic bauxite pebbles (derived from the Late Triassic - Camian - beds) and coarse clasts of black chert. Pilot X-ray diffraction analysis revealed mostly muscovite/illite, plus mixed-layer clay minerals of illite/montmorillonite type, chlorite plus mixed-layer clay minerals of chlorite/montmorillonite type, calcium montmorillonite, and diaspore plus gibbsite, or just traces of bauxite minerals (Misic, 2000). The mineral composition is not as uniform as might be expected, and further research, intended for application of factorial analysis, is in progress. A potential sediment source area in the present Cerkniscica River basin (Fig. 1) appears obvious at first glance, but similar outcrops of bauxite and chert do also appear at other sites that are not much more remote. 

These complex reactions are important for producing aluminum in industry. In the first step, one mixes Bauxite mineral with concentrated sodium hydroxide solution the tetrahydroxoaluminum complex will remove all the aluminum of the Bauxite. Then, aluminum hydroxide must be changed to aluminum oxide this compound is used in smelting flux electrolysis to finally produce pure aluminum metal. 

The other major raw material for zeolite production is the sodium aluminate solution. The production route to this important ingredient starts from bauxite minerals, for example, gibbsite [15,20,99,100,119,126,142,150-154]. The ore is extracted and purified via the Bayer process. The process encompasses the digestion of sodium aluminate by means of caustic soda and precipitation of purified aluminum trihydroxide [15,18,20,99,100,119,126,142,150-159]. 

Aluminum oxide or alumina (AbOg) is also known as corundum. It is the most widely used inorganic chemical for ceramics and is produced from fhe bauxite mineral. The production method is called the Bayer process. Bauxite is hydrated aluminum oxide with iron oxide (Pe203), silica (Si02), and titania (Ti02) as impurities. It is the result of the weathering of igneous aluminous rocks under tropical conditions. 

Starch is a polysaccharide found in many plant species. Com and potatoes are two common sources of industrial starch. The composition of starch varies somewhat in terms of the amount of branching of the polymer chains (11). Its principal use as a flocculant is in the Bayer process for extracting aluminum from bauxite ore. The digestion of bauxite in sodium hydroxide solution produces a suspension of finely divided iron minerals and siUcates, called red mud, in a highly alkaline Hquor. Starch is used to settle the red mud so that relatively pure alumina can be produced from the clarified Hquor. It has been largely replaced by acryHc acid and acrylamide-based (11,12) polymers, although a number of plants stiH add some starch in addition to synthetic polymers to reduce the level of residual suspended soHds in the Hquor. Starch [9005-25-8] can be modified with various reagents to produce semisynthetic polymers. The principal one of these is cationic starch, which is used as a retention aid in paper production as a component of a dual system (13,14) or a microparticle system (15). 

The CAS registry Hsts 5,037 aluminum-containing compounds exclusive of alloys and intermetaUics. Some of these are Hsted in Table 1. Except for nepheline and alunite in the USSR and Poland, bauxite is the raw material for all manufactured aluminum compounds. The term bauxite is used for ores that contain economically recoverable quantities of the aluminum hydroxide mineral gibbsite or the oxide—hydroxide forms boehmite and diaspore. 

C. A. Hamer, Held Extraction Processes forNon-Bauxitic Mlumina Materials, Canmet Report 77—54, Canada Center for Mineral and Energy Technology, August 1977. 

Potassium alum is manufactured by treating bauxite with sulfuric acid and then potassium sulfate. Alternatively, aluminum sulfate is reacted with potassium sulfate, or the mineral alum stone, alunite, can be calciaed and leached with sulfuric acid. Alunite is a basic potassium aluminum sulfate... 

High Alumina. The naturally occurring raw materials are bauxites, sillimanite [12141 5-6] group minerals, and diaspore clays (see Aluminum compounds). Other high alumina raw materials are made by beneficiation, blending, and other processing techniques. 

The possible content of hydrated alumina and iron. Hydrated alumina minerals like gibbsite [14762-49-3] Al(OH)2, boehmite [1318-23-6] AlOOH, and diaspore [14457-84-2] AlOOH, occur ia bauxitic clays. Bauxites grade chemically iato hydrated fermgiaous and manganiferous laterites. Hence, finely divided M2O2, usually hydrated, may be a significant constituent of a clay where M may be A1 or Fe. Hydrated colloidal s ica may play a role ia the sHppery and sticky properties of certain clays. 

Aluminum (third most abundant element) is found as the Al+ ion in oxides and as the complex ion AlFImportant minerals are bauxite, which is best described as a hydrated aluminum oxide, Al203-.xH20, and cryolite, NaaAlFs. The element is readily oxidized and is not found in an uncombined state in nature. 

Aluminum Oxide (Alumina, oAlumina, Corundum, Alandum). A1203, mw 101.96, v hard white cryst powd, mp 2045°, bp 2980°, d 3.965g/cc. Insol in w, v si sol in aq alkaline solns. Found in nature as a mineral such as bauxite. Lab prepn is by heating aluminum hydroxide to above 1100°. 

Aluminum is the most abundant metallic element in the Earth s crust and, after oxygen and silicon, the third most abundant element (see Fig. 14.1). However, the aluminum content in most minerals is low, and the commercial source of aluminum, bauxite, is a hydrated, impure oxide, Al203-xH20, where x can range from 1 to 3. Bauxite ore, which is red from the iron oxides that it contains (Fig. 14.23), is processed to obtain alumina, A1203, in the Bayer process. In this process, the ore is first treated with aqueous sodium hydroxide, which dissolves the amphoteric alumina as the aluminate ion, Al(OH)4 (aq). Carbon dioxide is then bubbled through the solution to remove OH ions as HCO and to convert some of the aluminate ions into aluminum hydroxide, which precipitates. The aluminum hydroxide is removed and dehydrated to the oxide by heating to 1200°C. 

The technologies involved in the minerals processing industry can be broken down into those where the desired metal component is in high concentration, such as scrap iron, iron ore, phosphate ore, and bauxite, and those where the concentration of the valuable constituent is low, such as gold and silver ore, lean copper ore, and certain types of scrap and wastes. 

C03-0100. A mineral is a chemical compound found in the Earth s crust. What are the chemical names of the following minerals (a) Ti02 (rutile) (b) PbS (galena) (c) AI2 O3 (bauxite) (d) CaC03... 

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