Describe the industrial extraction of copper metal from its major ore, chalcopyrite.

a) The formula of the major ore of copper metal is chalcopyrite.

$$\boxed{\text{CuFeS}_2}$$

b) Process (II) is froth flotation.

c) The reaction that occurs in stage (III) is the roasting of chalcopyrite in air to produce copper(I) sulfide and iron(II) oxide.

$$2\text{CuFeS}_2(s) + 4\text{O}_2(g) \rightarrow \text{Cu}_2\text{S}(s) + 2\text{FeO}(s) + 3\text{SO}_2(g)$$

d) In stage (IV), copper(I) sulfide is heated in a converter with air and sand ($\text{SiO}_2$). Iron impurities are oxidized to $\text{FeO}$, which reacts with $\text{SiO}_2$ to form $\text{FeSiO}_3$ slag. The $\text{Cu}_2\text{S}$ then undergoes self-reduction: some is oxidized to $\text{Cu}_2\text{O}$, which reacts with remaining $\text{Cu}_2\text{S}$ to produce molten copper and $\text{SO}_2$ gas. This molten copper is blister copper.

e) The half-cell equations for the reactions occurring at the anode and cathode in stage (VII) (electrolytic refining) are:

At the anode (oxidation):

$$\text{Cu}(s) \rightarrow \text{Cu}^{2+}(aq) + 2e^-$$

At the cathode (reduction):

$$\text{Cu}^{2+}(aq) + 2e^- \rightarrow \text{Cu}(s)$$