Question

State the role of silica in the metallurgy of copper .

Answer 1

Silica acts as an acidic flux during the metallurgy of copper It reacts with the impurities of iron and form slag. FeS is present is the form of impurity with copper sulphide ore.
$\underset{Gangue}{2FeS}+3O_2\to 2FeO+2S{O}_2\underset{Gangue}{FeO}+\underset{Flux}{Si{O}_2}\to \underset{Slag}{\underset{Ironsilicate}{FeSi{O}_3}}$

The role of silica in the metallurgy of copper is to remove the iron oxide obtained during the process of roasting as 'slag'. If the sulphide ore of copper contains iron, then silica SiO₂ is added as flux before roasting. Then, FeO combines with silica to form iron silicate, FeSiO₃ (slag).