Give one main difference between calcination and roasting?

Explanation

### Step-by-Step Text Solution:

1. **Definition of Calcination**:
- Calcination is a thermal treatment process where ore is heated in the absence of air. This process is often used to remove volatile substances or to drive off carbon dioxide from carbonate ores.

2. **Definition of Roasting**:
- Roasting is a thermal treatment process where ore is heated in the presence of air. This process is typically used to convert sulfide ores into oxides and to remove sulfur as sulfur dioxide gas.

...