Question

Identify the direct reduction reaction of iron ore in blast furnace:

• A. \( \text{Fe}_2\text{O}_3 + 3\text{C} \rightarrow 2\text{Fe} + 3\text{CO} \)
• B. \( \text{Fe}_2\text{O}_3 + 3\text{CO} \rightarrow 2\text{Fe} + 3\text{CO}_2 \)
• C. \( 3\text{FeO} + \text{CO}_2 \rightarrow \text{Fe}_3\text{O}_4 + \text{CO} \)
• D. \( 3\text{Fe}_2\text{O}_3 + \text{CO} \rightarrow 2\text{Fe}_3\text{O}_4 + \text{CO}_2 \)

Hint:

Remember the key distinction: Direct Reduction involves solid carbon (C), while Indirect Reduction involves carbon monoxide gas (CO). Look for the reducing agent on the reactant side of the equation.

Answer 1

The Correct Option is A

Step 1: Understanding the Concept:
In a blast furnace, the reduction of iron ore (oxides of iron like Fe\(_2\)O\(_3\) and Fe\(_3\)O\(_4\)) to metallic iron (Fe) occurs through two main mechanisms:

• Indirect Reduction: Reduction by a gaseous reducing agent, primarily carbon monoxide (CO). This occurs mainly in the upper and middle zones of the furnace where temperatures are lower.

• Direct Reduction: Reduction by a solid reducing agent, which is solid carbon (from coke). This occurs in the lower, high-temperature zone (bosh and hearth) of the furnace.
The question asks to identify the "direct reduction" reaction.

Step 3: Detailed Explanation:
Let's analyze the chemical reactions given in the options:

• (A) \( \text{Fe}_2\text{O}_3 + 3\text{C} \rightarrow 2\text{Fe} + 3\text{CO} \): This reaction shows iron oxide (Fe\(_2\)O\(_3\)) reacting directly with solid carbon (C). This is the definition of direct reduction. A more common direct reduction reaction in the furnace is \( \text{FeO} + \text{C} \rightarrow \text{Fe} + \text{CO} \), but the given reaction is also a valid representation of the principle.

• (B) \( \text{Fe}_2\text{O}_3 + 3\text{CO} \rightarrow 2\text{Fe} + 3\text{CO}_2 \): This shows iron oxide reacting with carbon monoxide (CO) gas. This is the primary indirect reduction reaction.

• (C) \( 3\text{FeO} + \text{CO}_2 \rightarrow \text{Fe}_3\text{O}_4 + \text{CO} \): This is an oxidation reaction of FeO by CO\(_2\), the reverse of a reduction step.

• (D) \( 3\text{Fe}_2\text{O}_3 + \text{CO} \rightarrow 2\text{Fe}_3\text{O}_4 + \text{CO}_2 \): This is the first step of indirect reduction, where hematite (Fe\(_2\)O\(_3\)) is reduced to magnetite (Fe\(_3\)O\(_4\)) by CO gas. It occurs in the upper part of the furnace stack.
Based on the definitions, only option (A) represents a direct reduction process.

Step 4: Final Answer:
The reaction \( \text{Fe}_2\text{O}_3 + 3\text{C} \rightarrow 2\text{Fe} + 3\text{CO} \) correctly represents the direct reduction of iron ore by solid carbon.