6.17 Why copper matte is put in silica lined converter?

Copper matte contains Cu2S and FeS. Copper matte is put in a silica-lined converter to remove the remaining FeO and FeS present in the matte as slag (FeSiO3). Also, some silica is added to the silica-lined converter. Then, a hot air blast is blown. As a result, the remaining FeS and FeO are converted to iron silicate (FeSiO3) and Cu2S is converted into metallic copper.
                    2 FeS + 3O2  2FeO + 2SO2FeO + SiO2  FeSiO32Cu2S + 3O2  2Cu2O + 2SO22Cu2O + Cu2S  6Cu + SO2