With a neat labelled diagram,describe the extraction of aluminium by Hall - Haroult process.

Explanation

exteraction of aliminium form bauxite , .A1. is extracted from bauxite `A1_2O_3. 2H_3 O` .
(i) Concentration of bauxite is done by leaching
(ii) Electrolytic Reduction (Hall - Herout process) . Purified bauxite ore is mixed with cryolite `( Na_3 AIF_6 )` or `CaF_2` which lowers its melting point and increases electrolysed using number of graphite rods as anode and carbon lining as cathode
The graphite anode is useful for reduction of metal
`2A1_2O_3 + 3C` to` 4A1+3CO_2`.
`Al_2O_3`.
`Al_2O_2 overset ("electrolysis")to 2Al^3 +3O^2- `
`Al^3(mel t ) + 3e^(-)to Al(l)`
`O^2-2e^-to O`
`O+O to O_2`
`C+O_2 to CO_2`
` O^2 - 2e to O `
` O+O to O_2
C+ O_2 to CO_2 `
Graphite rods get burnt forming `CO` and `CO_2` the aluminium thus obtaine is refined electrolyte cally using impure Al anode , pure Al as cathod and molten cryolite as electrolyte .
At anode : `Al to Al^3+ +3e^-`
At cathod `Al^3- + 3e^- to Al (pure)`