How aluminium is extracted from its ore by Hall - Heroult's process ?

Explanation

Hall- Heroult.s process is based on the electrolysis process of alumina. The alumina is dissolved in cryolite to decrease the melting point and increase the electrical conductivity. The electrolysis is carried in an iron tank inside with carbon. The carbon lining acts as the cathode. The carbon rods dipped in the fused electrolyte act as anode. In the electrolytic tank, electrolyte is covered with a layer of powdered cake. On passing electric current, electrolysis takes place as given below :
At cathode : `Al^(3+) + 3e^(-) to Al ,` At anode : `O^(2-) to O + 2e^(-)`
Here, aluminium is liberated at the cathode and tgets collected at the bottom of tha tank.