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Difficulty: MediumGeneral Principles of Metallurgy and Metal Extraction

In the industrial extraction of iron from haematite (Fe2O3Fe_2O_3) in a blast furnace, which chemical species acts as the primary reducing agent for reducing iron(III) oxide in the upper zone of the furnace?

  1. Carbon(II) oxide (COCO)Answer
  2. B
    Coke (CC)
  3. C
    Calcium oxide (CaOCaO)
  4. D
    Carbon(IV) oxide (CO2CO_2)

Answer

Carbon(II) oxide (COCO)
Gaseous carbon(II) oxide (COCO) is the primary reducing agent in the upper, cooler region of the blast furnace. It reduces iron(III) oxide (Fe2O3Fe_2O_3) to iron according to the reaction equation Fe2O3(s)+3CO(g)→2Fe+3CO2(g)Fe_2O_3(s) + 3CO(g) \rightarrow 2Fe + 3CO_2(g).

Step-by-Step Solution

1
Identify the chemical reactions producing reducing species in the blast furnace.
Coke reacts with oxygen to form carbon(IV) oxide, which is subsequently reduced by excess hot coke higher up in the furnace to yield carbon(II) oxide (CO2+C→2COCO_2 + C \rightarrow 2CO).
Gaseous carbon(II) oxide rises through the furnace and comes into intimate contact with descending iron ore.
2
Analyze the reduction step of haematite in the upper zone.
Gaseous COCO reduces Fe2O3Fe_2O_3 via the reaction Fe2O3(s)+3CO(g)→2Fe(s/l)+3CO2(g)Fe_2O_3(s) + 3CO(g) \rightarrow 2Fe(s/l) + 3CO_2(g).
Carbon(II) oxide is a powerful gaseous reducing agent at the moderate temperatures (400°C–700°C) found near the top of the furnace.

Key Concept

General Principles of Metallurgy and Metal Extraction - Reduction of Iron Ore in the Blast Furnace
Estimated Time:1m 0s
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General Principles of Metallurgy and Metal Extraction

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