Hoope’s refining process used for electrolytic refining of Aluminium:

Cathode : carbon electrodes

Anode : Fe tank lined with carbon bricks

Electrolyte : Na3AlF6 + BaF2

Bottom layer : Impure aluminium consists of Cu, Si etc in molten state.

Middle layer : molten mixtureof Fluorides of Na, Ba,Al andAl2O3

Top layer : pure molten aluminium.

On passing the current, Al is deposited at cathode from the middle layer and an equivalent amount of Al from the bottom layer moves into the middle layer leaving behind the impurities.

Chemical refining methods:

(1) Oxidative refining:

(i) Bessemerisation : Purification of iron from cast Iron or pig iron :

(ii) Cupellation : lead (Pb) present in Silver removed by Cupellation process:

(2) Parting Process:

(3) Polling process: This process is used for the purification of copper and tin.

(4) Electrolytic Refining:

(5) Kroll's Process and Imperial metal industries (IMI) Process of reduction;

(6) Vapour phase refining:

(A) Vapour phase refining : Mond's process:

(B) Vapour phase refining : Van Arkel–De Boer process :

(7) Parke's Process: Desilverisation of lead ;

(8) Pudding process: Used for the manufacture of wrought iron from cast iron: