In the Ellingham diagram, the Cu2O line is almost at the top. So it is quite easy to reduce oxide ores of copper directly to the metal by heating with coke (as can be seen in graph that the lines of C, CO and C, CO2 are at much lower positions).But most of the ores are sulphide and some may also contain iron. So, the sulphide ores are roasted/smelted to give oxides :
2Cu2S+3 O2 ––––▶ 2Cu2O+2SO2
The oxide can then be easily reduced to metallic copperusing coke :
Cu2S+C ––––▶ 2Cu+CO