General Principles and Processes of Isolation of Elements

During the extraction of copper, iron is present in the ore as impurity (FeS). The ore together with a little coke and silica is smelted; FeS present as impurity in the ore is oxidized to iron oxide, which then reacts with silica to form fusible ferrous silicate which is removed as slag. $2FeS+3O_2\to 2FeO+2S{O}_2$ $FeO+Si{O}_2\to \underset{\left(Slag\right)}{FeSi{O}_3}$