During heating the moisture gets expelled and the copper pyrites gets converted to ferrous sulfide and cuprous sulfide. \[ 2CuFeS_2 + O_2 \rightarrow Cu_2S + 2FeS + SO_2 \nonumber \] Blast furnace is used to heat the mixture of roasted ore, powdered coke and sand. In the blast furnace oxidation reactions takes place. Ferrous sulfide forms ferrous oxide which combines with silica and forms the slag (\(FeSiO_2\)). \[ 2FeS + 3O_2 \rightarrow 2FeO + 2SO_2 \nonumber \] \[ FeO + SiO_2 \rightarrow FeSiO_3 \nonumber \] Cuprous sulfide forms cuprous oxide which is partially converted to cuprous sulfide. \[ Cu_2S + 3 O_2 \rightarrow 2Cu_2O + 2SO_2 \nonumber \] \[ Cu_2O + FeS \rightarrow Cu_2S + FeO \nonumber \] This cuprous sulfide contains some amount of ferrous sulfide and this is called matte. Matte is removed from the base outlet of blast furnace. The removed matte is shifted into Bessemer converter which is lined inside with magnesium oxide. This converter has pipes through which hot air and \(SiO_2\) are sent in. In this converter \(Cu_2S\) converts to \(Cu_2O\) and \(FeS\) converts to \(FeO\). The ferrous oxide forms slag with \(SiO_2\).