Calcination involves heating ore:

Calcination is a metallurgical process where an ore is heated to high temperatures, but below its melting point, in the **absence or limited supply of air**. ### Key aspects of Calcination: 1. **Purpose:** To remove moisture, organic matter, and volatile impurities. It is also used to decompose carbonate ores and hydrated oxides into oxides. 2. **Common Reaction (Carbonates):** $$CaCO_3 (s) \xrightarrow{\Delta} CaO (s) + CO_2 (g)$$ $$ZnCO_3 (s) \xrightarrow{\Delta} ZnO (s) + CO_2 (g)$$ 3. **Difference from Roasting:** While calcination occurs in the absence or limited supply of air (typical for carbonates), roasting involves heating the ore in a regular supply of **excess air** (typical for sulfide ores like $ZnS$). Therefore, calcination involves heating ore in the absence of air.