Calcination and roasting are both ore processing metallurgical methods which are used to generate metal oxides. In both the methods, ores are heated below their melting points. There are a number of differences between the two:
- Calcination takes place in absence or limited supply of air (or oxygen). Roasting, on the other hand, is done in presence of air (or oxygen).
- Calcination removes the volatile impurities and moisture from the ore. Roasting, on the other hand, removes the impurities by oxidizing them and results in release of carbon dioxide and sulfur oxides.
- Calcination is commonly used for carbonate and bicarbonate ores, while roasting is more commonly used for sulfide ores.
- An example of calcination is the processing of calcium carbonate (CaCO3) ore. Roasting can be used for a sulfide ore like zinc sulfide (ZnS).
Hope this helps.