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Question
How does calcination differ from roasting?
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Solution
| Roasting | Calcination |
| Ore is heated in excess of air. | Ore is heated in the absence or limited supply of air. |
| This is used for sulphide ores. | This is used for carbonate ores. |
| SO2 is produced along with metal oxide. | CO2 is produced along with metal oxide. |
| e.g. \[\ce{ 2ZnS + 3O2 ->[\Delta] 2ZnO + 2SO2}\] | e.g. \[\ce{ZnCO3 ->[\Delta] ZnO + CO2}\] |
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