Aluminium hydroxide is produced from bauxite. Bauxite is refined to produce alumina from which aluminium metal is recovered by electrolytic reduction aluminium is also recycled from scrap.
Certain uses lead to the presence of aluminium in drinking water and foodstuffs.īauxite is the most important raw material used in the production of aluminium. Acidic precipitation mobilizes aluminium from natural sources, and direct anthropogenic releases of aluminium compounds associated with industrial processes occur mainly to air. Natural processes account for most of the redistribution of aluminium in the environment. And finally, the more recent analytical methods available for the study of chemical speciation in solids and solution, and for quantitative analysis, have been applied to the determination of aluminium and the identification of its various forms.Īluminium and its compounds comprise about 8% of the Earth’s surface aluminium occurs naturally in silicates, cryolite, and bauxite rock.
Few compounds of aluminium are classified in Annex 1 of the European Economic Union Council (EEC) Directive 67/1548, with aluminium powder and sodium aluminium fluoride (cryolite) as examples of exceptions, as well as compounds in which the anion renders them reactive such as aluminium phosphide. Aluminium oxides, hydroxides and oxyhydroxides occur in numerous crystallographic forms, which exhibit different surface properties. Like Mg 2+ and Ca 2+ ions, Al 3+ in most situations seeks out complexing agents with oxygen-atom donor sites such as carboxylate and phosphate groups, including in biological systems. The solubility of aluminium salts is governed by pH, because the aluminium(III)-cation (Al 3+) has a strong affinity for the hydroxide ion, which promotes precipitation.
Most aluminium compounds are solids exhibiting high melting points. Identity, Physical and Chemical Properties, Analytical MethodsĪ compendium is provided of aluminium compounds used in industrial settings, and as pharmaceuticals, food additives, cosmetics and as other household products.
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