In the metallurgy of copper, the flux used to remove the basic impurity of `FeO` is ______.

Answer

To solve the question regarding the flux used in the metallurgy of copper to remove the basic impurity FeO, we can follow these steps:

### Step 1: Identify the Impurity
The impurity mentioned in the question is FeO (iron oxide). In metallurgy, impurities are often referred to as gangue.

### Step 2: Determine the Nature of the Impurity
FeO is a basic oxide. In metallurgical processes, basic impurities need to be removed using an appropriate flux.

### Step 3: Understand the Role of Flux
A flux is a substance added to a metallurgical process to help remove impurities. It combines with the gangue to form a slag, which can be easily removed.

### Step 4: Identify the Suitable Flux
To remove a basic impurity like FeO, an acidic flux is required. The commonly used acidic flux in metallurgy is silica (SiO2).

### Step 5: Reaction Between Flux and Impurity
When silica (SiO2) is added to the process, it reacts with the basic impurity FeO to form a slag, specifically iron silicate (FeSiO3).

### Conclusion
Thus, the flux used to remove the basic impurity FeO in the metallurgy of copper is **silica (SiO2)**.

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