In the extraction process of copper, the product obtained after carrying out the reactions
(i) $2 \mathrm{Cu}_2 \mathrm{~S}+3 \mathrm{O}_2 \rightarrow 2 \mathrm{Cu}_2 \mathrm{O}+2 \mathrm{SO}_2$
(ii) $2 \mathrm{Cu}_2 \mathrm{~S}+\mathrm{Cu}_2 \mathrm{~S} \rightarrow 6 \mathrm{Cu}+\mathrm{SO}_2$ is called