Out of the following which ores are calcinated during extraction
(a) Copper pyrites (b) Malachite (c) Bauxite
Correct answer is

Options

A. a,b,c
B. b,c
C. Only a
D. All

Answer

To determine which ores are calcinated during extraction, let's analyze each of the given options: Copper pyrites, Malachite, and Bauxite.

### Step 1: Understanding Calcination
Calcination is a thermal treatment process where an ore is heated in the absence of air or in a limited supply of air. The main purpose of calcination is to convert ores into their metallic oxides, remove moisture, and eliminate volatile impurities. This process is typically used for carbonate ores and hydroxide ores.

### Step 2: Analyzing Each Ore
1. **Copper Pyrites (CuFeS2)**:
- This ore is primarily a sulfide mineral. The extraction process for copper from copper pyrites involves roasting, not calcination. Roasting converts sulfides to oxides by heating in the presence of air. Therefore, copper pyrites are **not calcinated**.

2. **Malachite (CuCO3·Cu(OH)2)**:
- Malachite is a carbonate mineral. When heated, it undergoes calcination to form copper oxide (CuO), water (H2O), and carbon dioxide (CO2). The reaction is as follows:
\[ \text{CuCO}_3 \cdot \text{Cu(OH)}_2 \rightarrow 2 \text{CuO} + \text{H}_2\text{O} + \text{CO}_2 \]
- Since it is a carbonate, Malachite is **calcinated**.

3. **Bauxite (Al2O3·2H2O)**:
- Bauxite is a hydrated aluminum oxide. During calcination, it is heated to remove water and convert it to alumina (Al2O3). The reaction can be summarized as:
\[ \text{Al}_2\text{O}_3 \cdot 2\text{H}_2\text{O} \rightarrow \text{Al}_2\text{O}_3 + 2\text{H}_2\text{O} \]
- Since it involves the removal of water from a hydroxide, Bauxite is also **calcinated**.

### Conclusion
From the analysis:
- **Copper pyrites**: Not calcinated (roasting process).
- **Malachite**: Calcinated.
- **Bauxite**: Calcinated.

Thus, the correct answer is **Malachite and Bauxite**.