Question

How is copper extracted from its sulphide ore (copper glance), Cu₂S? Explain with equations of the reactions involved.

Answer 1

Copper is a less reactive metal, which is quite low in the reactivity series. Copper metal can be extracted just by heating its sulphide ore in air.

The concentrated copper (I) sulphide ore (copper glance) is roasted in air, when a part of copper (I) sulphide is oxidised to copper (I) oxide.

\[\ce{\underset{(Copper glance ore)}{\underset{Copper (I) sulphide}{2Cu2S_{(s)}}} + \underset{(From air)}{\underset{Oxygen}{3O2_{(g)}}} ->[Roasting] \underset{Copper (I) oxide}{2Cu2O_{(s)}} + \underset{Sulphur dioxide}{2SO2_{(g)}}}\]

Once a sufficient quantity of copper (I) sulphide has been transformed into copper (I) oxide, the airflow for roasting is ceased. In the absence of air, the copper (I) oxide produced combines with the residual copper (I) sulphide to yield copper metal and sulphur dioxide.

\[\ce{\underset{(Formed above)}{\underset{Copper (I) oxide}{2Cu2O_{(s)}}} + \underset{(From unoxidised ore)}{\underset{Copper (I) sulphide}{Cu2S_{(s)}}} ->[Heat] \underset{Copper metal}{6Cu2_{(s)}} + \underset{Sulphur dioxide}{SO2_{(g)}}}\]