Which of the following statement is correct regarding `Cu` extraction ?

Options

A. In the smelting step, carbon reduction takes places
B. During roasting, `Cu_(2) S` remains almost unaffected
C. In Besse,er converter, only self-reduction occurs, not slag formation.
D. Blister formed in the blister `Cu` is due to dissolved `CO_(2)`

Answer

To determine which statement is correct regarding the extraction of copper (Cu), let's analyze each option step by step.

### Step-by-Step Solution:

1. **Statement A: In smelting step carbon reduction takes place.**
- This statement is incorrect. In the smelting process, copper oxide reacts with copper sulfide, leading to self-reduction. Carbon is not involved in this reduction process.

2. **Statement B: During roasting, copper sulfide remains almost unaffected.**
- This statement is correct. When roasting copper sulfide (CuFeS2), the reaction primarily produces copper sulfide and iron sulfide, with the liberation of sulfur dioxide (SO2). Only a small percentage of copper sulfide reacts to form copper oxide, indicating that the majority remains unaffected.

3. **Statement C: In Bessemer converter, only self-reduction happens, no slag formation.**
- This statement is incorrect. While self-reduction does occur in the Bessemer process, slag formation also takes place. The iron oxide (FeO) reacts with gangue impurities (SiO2) to form slag (FeSiO3).

4. **Statement D: Blister formed in the blister copper is due to dissolved carbon dioxide.**
- This statement is incorrect. The blister formation in blister copper is not due to dissolved carbon dioxide. Instead, it is primarily caused by the release of gases during the reduction process, and the presence of carbon does not contribute to blister formation.

### Conclusion:
The correct statement regarding copper extraction is **Statement B**: "During roasting, copper sulfide remains almost unaffected."

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