Question

What is the role of the following compound- 
SiO₂ in the extraction of copper from copper pyrites?

Answer 1

Role of SiO₂ in the extraction of copper from copper pyrites:

1. The copper matte containing Cu₂S and FeS is put in silica lined converter in order to remove impurities as fusible slag. Som silica is also added and hot air blast is blown to convert remaining FeS to FeO, which is removed as slag with silica.
   \[\ce{\underset{\text{Ferrous sulphide}}{2FeS} + \underset{\text{From blast of hot air}}{3O_2} -> \underset{\text{Ferrous oxide}}{2FeO} + \underset{\text{Sulphur dioxide}}{2SO_2}}\]
2. Ferrous oxide combines with silica (flux) to form fusible slag.
   \[\ce{\underset{\text{Ferrous oxide}}{FeO} + \underset{\text{Silica (Flux)}}{SiO_2} -> \underset{\text{Ferrous silicate (Fusible slag)}}{FeSiO_3}}\]