The main ore of lead is galena (PbS). Lend is extracted from galena ore either by (P) or (Q).

(P) $$\begin{gathered} \mathrm{PbS}\underset{\text{ in air }}{\stackrel{\text{ Roasted }}{⟶}}\mathrm{PbO}+{\mathrm{SO}}_2 \\ \downarrow \mathrm{Heated} \mathrm{with} \mathrm{C} \\ \downarrow \to \mathrm{Pb}+{\mathrm{CO}}_2 \end{gathered}$$

(Q) $$\begin{gathered} \mathrm{PbS}\underset{\text{ in air }}{\stackrel{\text{ Roasted }}{⟶}}\mathrm{PbO}+{\mathrm{SO}}_2 \\ \downarrow \mathrm{Heated} \mathrm{with} \mathrm{PbS} \\ \downarrow \to \mathrm{Pb}+{\mathrm{SO}}_2 \end{gathered}$$

Auto-reduction process is :