Describe the reaction occurring in a blast furnace during the extraction of iron.

by

Points to Remember:

  • The primary reaction in a blast furnace is the reduction of iron oxides to metallic iron.
  • Coke (carbon) acts as the reducing agent.
  • Hot air is blown in to provide oxygen for combustion and maintain high temperatures.
  • Several other chemical reactions occur simultaneously, including the formation of slag.

Introduction:

Iron extraction in a blast furnace is a complex high-temperature process involving several simultaneous chemical reactions. The overall goal is to reduce iron oxides (primarily Fe₂O₃ and Fe₃O₄) present in iron ore to metallic iron (Fe). This is achieved through a series of redox reactions, driven by the heat generated from the combustion of coke (a form of carbon) with hot air. The process is highly efficient, producing pig iron, a form of impure iron, which is then further refined.

Body:

1. Combustion of Coke:

Subscribe on YouTube

The process begins with the combustion of coke in the lower part of the furnace. Hot air is blown into the furnace, reacting with coke to produce carbon monoxide (CO) and heat:

2C(s) + O₂(g) → 2CO(g) + Heat

This exothermic reaction generates the high temperatures (around 2000°C) necessary for the subsequent reduction reactions.

2. Reduction of Iron Oxides:

The carbon monoxide produced then acts as the reducing agent, reacting with iron oxides in the upper regions of the furnace in a series of steps:

  • Reduction of Fe₂O₃ to Fe₃O₄: 3Fe₂O₃(s) + CO(g) → 2Fe₃O₄(s) + CO₂(g)
  • Reduction of Fe₃O₄ to FeO: Fe₃O₄(s) + CO(g) → 3FeO(s) + CO₂(g)
  • Reduction of FeO to Fe: FeO(s) + CO(g) → Fe(l) + CO₂(g)

These reactions are endothermic, meaning they absorb heat, which is supplied by the combustion of coke. The iron produced is molten due to the high temperature and collects at the bottom of the furnace.

3. Slag Formation:

Iron ore typically contains impurities like silica (SiO₂) and calcium carbonate (CaCO₃). These react with the added limestone (CaCO₃) at high temperatures to form slag, a molten mixture of calcium silicate (CaSiO₃):

Join Our Telegram Channel

CaCO₃(s) → CaO(s) + CO₂(g)
CaO(s) + SiO₂(s) → CaSiO₃(l)

Slag is less dense than molten iron and floats on top, allowing for easy separation. This removes impurities from the iron, improving its quality.

4. Other Reactions:

Several other minor reactions occur, including the reaction of carbon with iron oxides to form iron carbide (Fe₃C) and the reduction of some impurities by carbon monoxide.

Conclusion:

The blast furnace process is a highly efficient and effective method for extracting iron from its ores. The key reactions involve the combustion of coke to generate heat and carbon monoxide, which then reduces iron oxides to metallic iron. Simultaneously, slag formation removes impurities, resulting in relatively pure molten iron. The process is crucial for the steel industry, which relies on this pig iron as a raw material. Further research into optimizing the process, such as using alternative reducing agents to reduce carbon emissions, is crucial for sustainable iron production and minimizing the environmental impact. Continuous improvements in blast furnace technology, focusing on energy efficiency and waste reduction, are essential for a greener and more sustainable future for iron and steel manufacturing.

CGPCS Notes brings Prelims and Mains programs for CGPCS Prelims and CGPCS Mains Exam preparation. Various Programs initiated by CGPCS Notes are as follows:-

error: Content is protected !!