What is meant by refining of a metal? Name the most widely used methods of refining impure metals produced by various reduction processes. Describe with the help of a labelled diagram how this method may be used for refining of copper.

Refining of metals: Refining of metals is nothing but the removal of impurities from crude metals or purifying the crude metal.
Electrolytic refining is the most widely used method for the refining of metals.
Electrolysis of copper:

Electrolysis of copper from copper sulphate solution is done using copper electrodes. The crude copper serves as the anode while the thin sheet of pure copper serves as the cathode.
$$\begin{gathered} \mathrm{At}\mathrm{anode}:\mathrm{Cu}\to {\mathrm{Cu}}^{+2}+2{\mathrm{e}}^{-} \\ \mathrm{At}\mathrm{cathode}:{\mathrm{Cu}}^{+2}+2{\mathrm{e}}^{-}\to \mathrm{Cu} \end{gathered}$$
As the anode dissolves away, the cathodes on which the pure metal is deposited grow in size.