Metallergy is the process of

Options

A. Concentration of ore
B. Roasting of ore
C. Extraction of metal from ore
D. Both a and c

Explanation

**Step-by-Step Solution:**

1. **Definition of Metallurgy**: Metallurgy is a branch of chemistry that focuses on the extraction of metals from their ores and refining them to obtain pure metals.

2. **Processes Involved in Metallurgy**: The metallurgy process consists of several key steps:
- **Extraction of the Ore**: This is the initial step where the metal is obtained from its natural mineral deposits.
- **Separation and Concentration of Ore**: This involves removing impurities from the ore. The impurities are referred to as "gangue."
- **Reduction of the Ore**: This is the process of converting the concentrated ore into pure metal.

3. **Importance of Dressing**: Dressing is the process of removing gangue from the ore. This is crucial because impurities can hinder the extraction of pure metals.

4. **Use of Flux**: A flux is a substance used in metallurgy to help remove impurities during the refining process. It aids in the concentration of the ore.

5. **Methods of Concentration**: There are various methods used to concentrate the ore, including:
- Froth flotation method
- Crushing and grinding method

6. **Example of Roasting**: Roasting is a specific metallurgical process where a sulphide ore is heated in the presence of air. For instance, when copper pyrite (CuFeS2) is roasted, it converts to copper sulphide (Cu2S) along with the formation of iron sulphide (FeS) and sulfur dioxide (SO2).

7. **Conclusion**: Metallurgy encompasses the extraction and refining of metals from ores, involving several processes to ensure that the final product is pure and usable.

---