Question

Which of the following factors is of no significance for roasting sulphide ores to the oxides and not subjecting the sulphide ores to carbon reduction directly?

• A. CO2 is thermodynamically more stable than CS2
• B. Metal sulphides are less stable than the corresponding oxides
• C. CO2 is more volatile than CS2
• D. Metal sulphides are thermodynamically more stable than CS2

Answer 1

Answer: (C)

CO2 is more volatile than CS2

Answer 2

(3) It is true that this statement has no significance for roasting sulphide ores to the oxides.

The Gibb’s energies of formation of most sulphides are greater than that for CS2. In fact, CS2 is an endothermic compound. There, the DƒGQ of MXS is not compensated. So reduction of MXS is difficult. Hence it is common practice to roast sulphide ores to corresponding oxides prior to reduction.