Question

Write short note on the following:

Calcination

Answer 1

1. Calcination is the process of heating concentrated ore in a limited supply of air, below its melting point.
2. It removes moisture and volatile impurities from the ore.
3. The ore becomes porous and dry.
4. Carbonate ores decompose into oxides, releasing carbon dioxide (e.g., \[\ce{CaCO3 -> CaO + CO2}\]).
5. Hydrated oxides lose water of crystallisation and get dehydrated (e.g., \[\ce{Fe2O3 * 3H2O -> Fe2O3 + 3H2O}\]).
6. Typically done with carbonate ores at temperatures around 670-770 K, except CaCO₃ requiring about 1270 K.
7. It prepares the ore for further metallurgical processes like roasting or smelting.