Question

Explain with reason:

Roasting is carried out on sulphide ores and not on carbonate ores.

Answer 1

Roasting provides oxygen to convert metallic sulphides into metallic oxide and \[\ce{SO2}\] which takes place when heated in excess of air.

Carbonate is converted into oxide by loss of \[\ce{CO2}\] which takes place in the absence of air and when heated strongly.

\[\ce{CaCO3 ->[\Delta] CaO + CO2}\]

\[\ce{2PbS + 3O2 -> 2PbO + 2SO2 ^}\]