Extraction of $Cu$ from copper pyrites $\left( CuFeS _{2}\right)$ involves.
$\rightarrow$ Crushing followed by concentration of the ore by froth flotation
$\rightarrow$ removal of iron as slag
$FeO +\underset{\text{acidic flux}}{SiO _{2}} \longrightarrow \underset{\text{Slag}}{FeSiO _{3}}$
$\rightarrow$ Self-reduction step to produce 'blister copper' following evolution of $SO _{2}$,
$Cu _{2} S +2 Cu _{2} O \longrightarrow \underset{\text{bliscer copper}}{6 Cu}+ SO _{2} \uparrow$