Write the method to produce copper matte from copper pyrites.

Answer

To produce copper matte from copper pyrites (CuFeS₂), we follow a series of steps involving froth flotation, roasting, and smelting. Here’s a detailed step-by-step process:

### Step 1: Froth Flotation
- **Process**: The first step is to concentrate the copper pyrites. This is done using the froth flotation method. In this process, the crushed ore is mixed with water and a suitable frothing agent. Air is blown through the mixture, creating bubbles. The copper sulfide particles attach to the bubbles and rise to the surface, forming a froth.
- **Outcome**: The froth is skimmed off, and it contains about 25-30% pure copper concentrate, while the impurities settle at the bottom.

### Step 2: Roasting
- **Process**: The concentrated copper sulfide (copper concentrate) obtained from froth flotation is then subjected to roasting. During roasting, the concentrate is heated in the presence of oxygen. This process converts the copper sulfide into copper oxide and sulfur dioxide gas.
- **Chemical Reaction**:
\[ 2 \text{CuFeS}_2 + 4 \text{O}_2 \rightarrow 2 \text{Cu}_2\text{O} + 2 \text{FeO} + 4 \text{SO}_2 \]
- **Outcome**: The sulfur dioxide gas is released, and we obtain a mixture of copper oxide and iron oxide.

### Step 3: Smelting
- **Process**: The roasted product is then subjected to smelting. In this step, the copper oxide is mixed with silica and heated in a furnace. The silica reacts with the iron oxide to form slag (ferrous silicate), which can be removed.
- **Chemical Reactions**:
1. Formation of slag:
\[ \text{FeO} + \text{SiO}_2 \rightarrow \text{FeSiO}_3 \quad (\text{slag}) \]
2. Reduction of copper oxide:
\[ \text{Cu}_2\text{O} + \text{C} \rightarrow 2 \text{Cu} + \text{CO} \]
- **Outcome**: The final product is copper matte, which contains a mixture of copper and iron sulfides. The slag is removed, and pure copper can be extracted from the matte through further refining if necessary.

### Summary of the Process:
1. **Froth Flotation**: Concentration of copper pyrites to obtain copper concentrate.
2. **Roasting**: Conversion of copper sulfide to copper oxide and sulfur dioxide.
3. **Smelting**: Reduction of copper oxide to copper and formation of slag.

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