Which of the following metal's ore is/are concentrated by leaching method?

Options

A. Al
B. Fe
C. Au
D. Ag

Answer

To determine which metal's ore is concentrated by the leaching method, we need to understand the leaching process and identify the ores of the given metals that can be concentrated using this method.

### Step-by-Step Solution:

1. **Understand the Leaching Process**:
- Leaching is a chemical process where a reagent is used to dissolve the ore of a metal, allowing the impurities to remain undissolved. The soluble product is the concentrated ore.

2. **Identify the Metals and Their Ores**:
- The metals mentioned in the question are likely to include aluminum, gold, silver, and iron. We need to check which of these can be concentrated using leaching.

3. **Analyze Each Metal**:
- **Aluminum**: The ore of aluminum is Al₂O₃·2H₂O (bauxite). It can be concentrated using sodium hydroxide (NaOH), which reacts with aluminum oxide to form sodium aluminate (NaAlO₂), a soluble complex.
- **Gold**: Gold ore can be concentrated using sodium cyanide (NaCN). The reaction forms a soluble complex, allowing the gold to be extracted.
- **Silver**: Silver ore, particularly silver sulfide (Ag₂S), can also be concentrated using sodium cyanide (NaCN), forming a soluble complex that allows for the extraction of silver.
- **Iron**: Iron ore (like hematite, Fe₂O₃) is not concentrated by leaching. It typically undergoes other processes such as roasting or smelting.

4. **Conclusion**:
- The metals whose ores can be concentrated by the leaching method are aluminum, gold, and silver. Iron does not undergo concentration by this method.

### Final Answer:
The metals whose ores are concentrated by the leaching method are **Aluminum, Gold, and Silver**.