The main source of lead is $\mathrm{PbS}$. It is converted to $\mathrm{Pb}$ by:

Self - reduction process is:

Identify the metal $\mathrm{M}$ whose extraction is based on the following reactions:

$\mathrm{MS}+2{\mathrm{O}}_2\to {\mathrm{MSO}}_4$

$2\mathrm{MS}+3{\mathrm{O}}_2\to 2\mathrm{MO}+2{\mathrm{SO}}_2$

$\mathrm{MS}+2\mathrm{MO}\to 3\mathrm{M}+{\mathrm{SO}}_2$

$\mathrm{MS}+{\mathrm{MSO}}_4\to 2\mathrm{M}+2{\mathrm{SO}}_2$