State the role of silica in the metallurgy of copper.

(N/A) During the roasting of copper pyrite ore $(CuFeS_{2})$,a mixture of $FeO$ and $Cu_{2}O$ is obtained.
$2CuFeS_{2} + O_{2} \xrightarrow{\Delta} Cu_{2}S + 2FeS + SO_{2}$
$2Cu_{2}S + 3O_{2} \xrightarrow{\Delta} 2Cu_{2}O + 2SO_{2}$
$2FeS + 3O_{2} \xrightarrow{\Delta} 2FeO + 2SO_{2}$
The role of silica $(SiO_{2})$ in the metallurgy of copper is to act as an acidic flux to remove the basic impurity,iron$(II)$ oxide $(FeO)$,which is formed during the roasting process.
$FeO$ combines with silica to form iron$(II)$ silicate,$FeSiO_{3}$,which is known as slag.
$FeO + SiO_{2} \xrightarrow{\Delta} FeSiO_{3} \text{ (Slag)}$