Question

How is copper extracted from its sulphide ore? Explain the various steps supported by chemical equations.
Draw labelled diagram for the electrolytic refining of copper :

Answer 1

Metals low in activity series like copper are very unreactive. The oxides of these metals can be reduced to metals by heating alone. Copper is found as $C{u}_{2}S$ in nature. It can be formed just heating it in air.

$2C{u}_{2}S+3O_2\stackrel{Heat}{\to }2C{u}_{2}O+S{O}_2\uparrow$

$2C{u}_{2}O+C{u}_{2}S\stackrel{Heat}{\to }6Cu+S{O}_2\uparrow$

Then electrolytic refining of copper is carried out to remove the rest of the impurities present in the ore. The impure copper is made anode and strip of pure copper are made cathode. On passing the current as shown in the diagram, the pure copper from the anode dissolves into an electrolyte. An equivalent amount of copper is deposited on the cathode. Soluble impurities remain in the solution, whereas insoluble impurities settle at the bottom of the anode.