Copper Matte is the mixture of copper sulphide (Cu2S) and some iron sulphide (FeS). Matte is the phase where copper is extracted prior to the final reduction. The roasted ore is mixed with coke and silica (sand) SiO2 and is introduced in to a blast furnace. The hot air is blasted and FeO is converted in to ferrous silicate (FeSiO3). FeSiO3 (slag) floats over the molten matte of copper.