Blast Furnace Iron Extraction Chemistry

Steps:

• Coke burns with air to produce CO, which acts as the reducing agent for haematite (Fe₂O₃).
• Haematite is reduced by CO to iron metal and CO₂.
• Calcium carbonate (limestone) decomposes to CaO, forming slag with silica impurities.
• Evaluate options against reduction and impurity removal processes.

Why A is correct:

• Calcium carbonate decomposes to CaO (quicklime), which reacts with acidic SiO₂ impurities to form neutral slag (CaSiO₃), per the formula CaCO₃ → CaO + CO₂ followed by CaO + SiO₂ → CaSiO₃.

Why the others are wrong:

• B: Coke (carbon) is oxidized to CO and CO₂, not reduced.
• C: Haematite (Fe₂O₃) is reduced by CO to Fe, not oxidized.
• D: Haematite is reduced chemically by CO, not decomposed by heat alone.

Final answer: A