2ZnS + 7,O ➡ ZnO + ZnSO4 + SO2
is suggested by Peters as a probable reaction occurring to this material under roasting conditions.
Lead Sulphide is also occasionally present with copper ores. It melts readily, and is not entirely decomposed at the temperatures employed for the roasting of copper ores. The reactions on oxidation are largely analogous to those for other sulphides.
 | |
| PbS + O2 ➡ Pb + SO2 | |
| Pb + O ➡ PbO | |
or,
PbS + 3.O ➡ PbO + SO2.
Also,
2PbO + SO3 ➡ PbSO4.PbO (basic sulphate).
Arsenides are partly left as the corresponding oxides, whilst some As4O6 is evolved, and some basic arsenate generally remains.