Reduction of haematite by carbon monoxide in iron extraction

Steps:

• Hot air blasts into furnace, burning coke to form carbon monoxide (CO).
• CO acts as reducing agent, reacting with haematite (Fe₂O₃) to produce iron: Fe₂O₃ + 3CO → 2Fe + 3CO₂.
• Limestone (CaCO₃) decomposes to CaO, which removes silica impurities as slag.
• Molten iron sinks and is tapped off, separating from slag.

Why B is correct:

• Haematite reduction by CO is the core reaction yielding iron, per the blast furnace process equation Fe₂O₃ + 3CO → 2Fe + 3CO₂.

Why the others are wrong:

• A: Calcium carbonate removes impurities via slag formation, but it's a supporting step, not the iron-producing process.
• C: Haematite is reduced, not oxidised; CO₂ is a byproduct, not an oxidising agent.
• D: Haematite requires reduction, not thermal decomposition, which wouldn't yield iron.

Final answer: B