Cambridge O Level Chemistry · Syllabus 5070 · Metals
Blast Furnace
What is Blast Furnace?
The tall furnace in which iron is extracted from its ore. Hematite, coke and limestone are fed in at the top and hot air is blasted in at the bottom; carbon monoxide formed from the coke reduces the iron(III) oxide to molten iron, while calcium oxide from the limestone removes sandy impurities as molten slag.
This definition is part of the Metals chapter in Cambridge O Level Chemistry.
Common mistakes with Blast Furnace
- 9. “Coke reduces the iron(III) oxide in the blast furnace.” Repair In the route you are required to give, the reducing agent is carbon monoxide: \(\mathrm{Fe_2O_3 + 3CO \rightarrow 2Fe + 3CO_2}\). The coke does two other jobs — it burns to release heat and carbon dioxide, and it then converts that carbon dioxide into the carbon monoxide that does the reducing. Where Lesson 9.6B.
- 21. “The coke reduces the iron(III) oxide in the blast furnace.” Defect Names the wrong reducing agent for the required route. Reason The coke burns to carbon dioxide and then converts it to carbon monoxide; it is the carbon monoxide that reduces the ore. Repair \(\mathrm{Fe_2O_3 + 3CO \rightarrow 2Fe + 3CO_2}\), with coke named as the fuel and the source of the carbon monoxide. Transfer Which equation makes the reducing agent? \(\mathrm{CO_2 + C \rightarrow 2CO}\).
Questions students ask about Blast Furnace
What actually reduces the iron(III) oxide in the blast furnace?
Carbon monoxide is the reducing agent: \(\mathrm{Fe_2O_3 + 3CO \rightarrow 2Fe + 3CO_2}\). Coke itself is not the reducing agent in this route — it burns to release heat and carbon dioxide, and that carbon dioxide then reacts with more coke to form the carbon monoxide that reduces the ore.
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