In the extraction of iron in the blast furnace, phosphorous separates as

Options

A. Slag, `Ca_3(PO_4)_2`
B. Slag, `Mg_3(PO_4)_2`
C. Volatile, `P_2O_5`
D. `Ca_3P_2`

Answer

To solve the question regarding the separation of phosphorus in the extraction of iron in the blast furnace, we will analyze the information provided step by step.

### Step-by-Step Solution:

1. **Understanding the Process**: The extraction of iron in a blast furnace involves the reduction of iron ore (usually iron oxide) using carbon (from coke) at high temperatures. Limestone (calcium carbonate) is added to remove impurities.

2. **Role of Limestone**: Limestone decomposes in the furnace to form calcium oxide (CaO), which reacts with silica (SiO2) to form slag. This slag is crucial for removing impurities from the iron.

3. **Phosphorus in Iron Ore**: Phosphorus is an impurity that can be present in iron ores. During the blast furnace process, it needs to be removed to improve the quality of the iron.

4. **Formation of Slag**: The phosphorus combines with calcium oxide to form calcium phosphate. The reaction can be represented as:
\[ 6 \text{CaO} + \text{P}_4\text{O}_{16} \rightarrow 2 \text{Ca}_3\text{PO}_4 \cdots \]
This indicates that phosphorus is removed in the form of calcium phosphate.

5. **Identifying the Correct Option**: The options given in the question are:
- a. \( \text{Ca}_3\text{PO}_4 \cdots \) (calcium phosphate)
- b. \( \text{Mg}_3\text{PO}_4 \cdots \) (magnesium phosphate)
- c. \( \text{P}_2\text{O}_5 \) (phosphorus pentoxide)
- d. \( \text{Ca}_3\text{P}_2 \) (calcium phosphide)

From the reaction, we can see that phosphorus separates as calcium phosphate, which corresponds to option (a) \( \text{Ca}_3\text{PO}_4 \cdots \).

6. **Conclusion**: Therefore, the correct answer to the question is:
\[ \text{Phosphorus separates as } \text{Ca}_3\text{PO}_4 \cdots \text{ (slag).} \]

### Final Answer:
**Phosphorus separates as \( \text{Ca}_3\text{PO}_4 \cdots \) (slag).**

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