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CH1012
ALUMINIUM
1. Aluminium electrometallurgy
• Most abundant
metal by mass in the crust.
• the most common ore is bauxite (mostly Al2O3.nH2O - alumina, + SiO2, Fe2O3, TiO2)
eg. Weipa COMALCO mine
• Step 1: bauxite is purified to obtain pure alumina Al2O3(s).
The hydrometallurgical Bayer process uses NaOH (dissolves amph. alumina & leaves Fe2O3 behind) then add H+.
Al2O3(s) + 3H2O + 2OH-(aq) D 2Al(OH)4-(aq)
Al2O3(s) + 3H2O + 2OH-(aq) D 2Al(OH)4-(aq)
eg. Gladstone QAL refinery
• Step
2: the Hall-Heroult process
is used to produce aluminum metal from alumina using electrolysis.
is used to produce aluminum metal from alumina using electrolysis.
eg.
Gladstone COMALCO Boyne smelter
