When copper pyrite is roasted in excess of air, a mixture of Cu2S and FeO are formed. FeO is present as impurity. This can be removed as slag during Smelting. The flux added to form slag is
When copper pyrites is roasted in excess of air, a mixture of CuO + FeO is formed. FeO is present as impurity. This can be removed as slag during reduction of CuO. The flux added to form slag is