Question

Why is partial roasting of sulphide ore done in metallurgy of copper?

• A. Auto-reduction of $Cu_2O$ formed is carried out by remaining $Cu_2S$ in the reaction
• B. $Cu$ is separated out by partial reduction due to sedimentation
• C. Due to difference in gravity $Cu_2O$ and $Cu_2S$ are separated
• D. Complete roasting cannot be done in one step hence partial roasting is done

Answer 1

Answer: (A)

Auto-reduction of $Cu_2O$ formed is carried out by remaining $Cu_2S$ in the reaction

Answer 2

Partial roasting of sulphide ore forms some oxide. This oxide then reduces the remaining sulphide ore into metal. $2Cu_2S + 3O_2 \to 2Cu_2O + 2SO_2$ $2Cu_2O + Cu_2S \to 6Cu + SO_2$ This process is called autoreduction.