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Chemistry

METALS AND THEIR COMPOUND

Aluminum can be obtained as Kaolin, Al2O3.2SiO3.2H2O, cryolite. Na3AlF6, Corundum Al2O3 and mica K2O.Al2O3.6SiO2. NB: the main source of aluminum is bauxite Al2O3.2H2O   Extraction Aluminum can be found in clay and rocks, but due to their high silica content, they can not be used for extraction of aluminum. The extraction of aluminum is carried out by electrolysis of bauxite. The extraction proceeds in two stages.   Purification of Bauxite Bauxite is first heated with caustic soda solution under pressure to form soluble sodium aluminate(III) Al2O3 + 2NaOH + 3H2O                     2NaAl(OH)4 The impurities, iron III oxide and trioxosilicates (iv) can be filtered off as a sludge. The filterate contains aluminate (III) and then seeded with aluminum hydroxide crystals to induce precipitation of aluminum hydroxide. NaAl(OH)4        Al(OH)3  + NaOH The Al(OH)3 is then filtered off, washed, dried and heated strongly to yield pure aluminium oxide or alumina while the… Read More »METALS AND THEIR COMPOUND

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