Which of the following is not a concentration technique?

Options

A. Levigation
B. Froth-flotation
C. Leaching
D. Calcination

Answer

To determine which of the following is not a concentration technique, we need to understand the different methods of concentration used in the isolation of elements. Concentration techniques can be classified into two main categories: chemical processes and physical processes.

### Step-by-Step Solution:

1. **Identify Concentration Techniques**: Concentration techniques are methods used to increase the concentration of a desired substance from a mixture. These techniques can be either chemical or physical.

2. **List Chemical Concentration Techniques**: The primary chemical concentration technique is:
- **Leaching**: This involves the extraction of a substance from a solid material by dissolving it in a liquid.

3. **List Physical Concentration Techniques**: The physical concentration techniques include:
- **Gravitational Separation**: This method uses gravity to separate particles based on their density.
- **Froth Flotation**: A process that separates hydrophobic materials from hydrophilic ones using bubbles.
- **Levigation**: This involves the separation of fine particles from coarser ones using water.
- **Hydraulic Washing**: A technique that uses water to wash away lighter impurities from heavier ore.
- **Wilfley Table**: A device used for separating particles based on their specific gravity.

4. **Identify the Non-Concentration Technique**: Among the listed techniques, we need to identify which one is not a concentration technique. The process of **Calcination** is mentioned as a technique that converts metal to metal oxide, which does not fit into the category of concentration techniques. Instead, it is a method used to heat substances in the absence of air.

5. **Conclusion**: Therefore, the option that is not a concentration technique is **Calcination**.

### Final Answer:
**Calcination** is not a concentration technique.

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