Various methods adopted in purification of metals :
- Distillation : This method is very useful for purification of low boiling metals like zinc and mercury containing high boiling metals as impurities. The extracted metal in the molten state is distilled to obtain the pure metals as distillate.
- Poling : The molten metal is stirred with logs (poles) of greenwood. The impurities are removed either as gases or they get oxidized and form slag over the surface of molten metal.
- Liquation : Low melting metal like tin can be made to flow on a slope surface to separate it from high melting impurities.
- Electrolytic refining : In electrolytic refining impure metal is made as anode and pure metal is made as cathode and they are put in a electrolytic path containing soluble salt of the same metal.
The required metal gets deposited on the cathode in the pure form.