Lead is extracted from galena (PbS), either by Following ways.
$$\begin{gathered} \left(\mathrm{i}\right) \mathrm{PbS}\underset{-{\mathrm{SO}}_2}{\overset{\mathrm{Roasted} \mathrm{in} air}{\to }}\mathrm{PbO}\underset{-{\mathrm{CO}}_2}{\overset{\mathrm{Heated} \mathrm{with} \mathrm{C}}{\to }}\mathrm{Pb} \\ \left(\mathrm{ii}\right) \mathrm{PbS}\underset{-{\mathrm{SO}}_2}{\overset{\mathrm{Roasted} \mathrm{in} air}{\to }}\mathrm{PbO}\stackrel{\mathrm{Heated} \mathrm{with} \mathrm{PbS}}{\to } \mathrm{Pb}+ {\mathrm{SO}}_2 \end{gathered}$$
Auto-reduction process is