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About aluminum
Aluminum (Aluminium) is an element of the periodic table III.A group. Aluminum has an oxidation number 0, has 3 valence electrons 3s2 3p 1st Located in the III group (they are aluminum compounds and aluminates).
Aluminum (Aluminium) is silver-grey, hard and lightweight metal. Is a good conductor of heat, electricity, and has good mechanical properties. Aluminum is a good, ductile metal for hot and cold making. Melting point of aluminum is 659°C; boiling point is 2500°C.
Aluminum (Aluminium) is Specific el. resistance is 0.02778 mm2/m. In the Beketov voltage range of metals there is aluminum on the left side from hydrogen and that’s why aluminum is a very electropositive metal. Aluminum density is 2.7 g/cm3.
Aluminum is made from bauxite. Direct production of aluminum is not possible and therefore is produced in two stages: the production begins with pure Al203, which is processed into a metal by electrolysis of aluminum.
The main raw material for the production of aluminum is bauxite, containing 55 to 65% Al203, can be produced from other kinds of raw materials such as kaolin, syenite, inorganic constituents, nepheline, etc., but not worth it, because the production is very expensive. Sometimes it is a combined production of Al203 and alkali, eventually cement. Al production processes 203 are divided into acidic and alkaline processes. Acid method is used to process neobouxite raw materials. The Bayern alkaline march is based on the principle of decomposition of bauxite with sodium lye at higher temperatures and pressures in the autoclave. This creates a sodium aluminate and insoluble residue. Since the solution is separated by settling and filtering. Sodium aluminate is stirred, vaccination, aluminum hydroxide and then diluting the decomposed Al (OH)3 and NaOH. Aluminum hydroxide is calcined at 1200oC to Al203, is the final raw material for aluminum electrolysis by Bayern alkaline march, suitable for processing high silica bauxite with a module that is converted to Al203. These procedures are very expensive and therefore are not use in the industry. Metallic aluminum is produced by fusing the electrolysis; this method produced aluminum has a purity of 99.5% Al more.
The main impurity in the iron and aluminum is silicium. Aluminum, which depletes the electrolysis van into a holding furnace, is transferred in the basins of which are either casted pieces called billets, or blanks (wire, bricks, etc.) to remove non-metallic impurities and Gas is used for refining processes by refining salt, chlorination, etc. Very clean aluminum is used to make special aluminum alloys used in electrical engineering, chemistry, in a car engine.
Compound elements are:
- Al2O3 - alumina (ruby, emery, corundum)
- Na3AlF6 - kexafluorohlinitan sodium (cryolite)
- AlCl3 - aluminum chloride
- Al2(SO4)3 - aluminum sulphate
- Al(CH3COO)3 - aluminum acetate Al
- K Al (OH)4 - tetrahydroxohliniton Potassium
- Al (OH) - aluminum hydroxide
- Al2 (HPO4)3 aluminum secondary phosphate
Aluminum is the second most used feature of the iron. Aluminum is used mainly as an electrical conductor, in chemistry as an ingredient in compounds. It is also used for high-voltage lines because it is cheaper and lighter than mainly copper. It is also used as food packaging (aluminum foil, aluminum foil). Very often we encounter the concept of alloy, which is an alloy of manganese, magnesium and copper. Increasingly used as a building material because of its strength.
Used Literature:
- Čipera J. Chemie A SPN Praha 1984
- Technický naučný slovník 2 díl E – I Praha 1982
- ABC číslo čas. 9. ročník 11. Rok 1989 J. Kukla Význam hliníku
- J.Lauš Elektrotechnické materiály INCOTEX Brno 1991
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