Which of the following statements is correct for roasting

Options

A. convert sulphide to oxide
B. Convert sulphide to carbonate
C. Remove aresnic and sulphur impurities
D. melt the ore

Answer

**Step-by-Step Solution:**

1. **Understanding Roasting:**
- Roasting is a metallurgical process used to convert ores into their metallic oxides. This process involves heating the ore strongly in the presence of excess air (oxygen) but at a temperature that is insufficient to melt the ore.

2. **Chemical Reaction:**
- A common example of roasting is the conversion of zinc sulfide (ZnS) to zinc oxide (ZnO) and sulfur dioxide (SO2). The reaction can be represented as:
\[ 2 \text{ZnS} + 3 \text{O}_2 \rightarrow 2 \text{ZnO} + 2 \text{SO}_2 \]
- This shows that sulfide ores are converted into their respective oxides.

3. **Key Features of Roasting:**
- During roasting, moisture is removed from the ore.
- Organic matter present in the ore is destroyed.
- Non-volatile impurities such as sulfur, phosphorus, and arsenic are oxidized and removed as volatile gases.

4. **Example of Impurity Removal:**
- For instance, arsenic (As) can be oxidized during roasting:
\[ 4 \text{As} + 3 \text{O}_2 \rightarrow 2 \text{As}_2\text{O}_3 \]
- This indicates that arsenic is converted into arsenic trioxide, which is a volatile compound and can be removed from the process.

5. **Conclusion on Correct Statements:**
- Based on the above understanding, the correct statements regarding roasting are:
- It converts sulfide ores to oxides (correct).
- It does not melt the ore (correct).
- Moisture and organic matter are removed, and non-volatile impurities are oxidized (correct).
- Therefore, the correct options regarding roasting are options that highlight these features.