Question

What is calcination? Give an example.

Hint:

To remember the difference: - Calcination is for Carbonates (heated in limited air). - Roasting is for Sulphides (heated in excess air).

Answer 1

Concept: Calcination is a metallurgical process used to convert ore into its oxide. It is a critical step in the extraction of metals from their naturally occurring forms, such as carbonates or hydrated oxides.
Calcination is the process of heating the ore strongly in the absence of air or in a limited supply of air, at a temperature below its melting point.
The primary objectives of calcination are: • To remove moisture from hydrated ores. • To remove volatile impurities. • To decompose carbonate ores into metal oxides by expelling carbon dioxide.
A common example is the calcination of Zinc Carbonate (Calamine ore). When heated, it decomposes to form Zinc Oxide and releases Carbon Dioxide gas: ZnCO₃(s) Δ ZnO(s) + CO₂(g)
Another example is the calcination of Limestone: CaCO₃(s) Δ CaO(s) + CO₂(g)