Roasting and calcination are

Options

A. used for the purification of metals
B. usually carried out in reverberatory furnace
C. employed for the concentration of the ore
D. different names of the same operation

Answer

### Step-by-Step Solution:

1. **Definition of Roasting and Calcination**:
- Roasting and calcination are two processes used in metallurgy for the extraction of metals from their ores.

2. **Roasting**:
- Roasting involves heating the ore in the presence of oxygen.
- This process is typically done at a temperature below the melting point of the metal.
- The purpose of roasting is to convert the ore into a more usable form, often by removing impurities or converting metal sulfides into oxides.

3. **Calcination**:
- Calcination, on the other hand, is the process of heating the ore in the absence of air (or oxygen).
- Similar to roasting, calcination is also performed below the melting point of the metal.
- The main aim of calcination is to drive off volatile substances, such as water or carbon dioxide, and to convert the ore into an oxide.

4. **Comparison of Roasting and Calcination**:
- Both processes are essential for the preparation of ores before they undergo further reduction to extract the metal.
- They are not the same operation; they serve different purposes and are conducted under different conditions.

5. **Options Analysis**:
- Option 1: "Used for purification of metal" - Incorrect, as they are primarily for ore preparation.
- Option 2: "Usually carried out in reverberatory furnace" - Correct, as both processes can be performed in this type of furnace.
- Option 3: "Employed for concentration of the ore" - Incorrect, as they are not primarily for concentration.
- Option 4: "Different names of the same operation" - Incorrect, as they are distinct processes.

6. **Conclusion**:
- The correct answer is option 2: "Usually carried out in reverberatory furnace."