Extraction of Iron from Haematite in Blast Furnace: Effectiveness of Reducing Agents

Introduction:
The extraction of iron from haematite (iron ore) is carried out in a blast furnace. The blast furnace is a large cylindrical tower-like structure made of steel. It is lined with refractory bricks and has a height of around 30 meters. The purpose of the blast furnace is to reduce the iron oxide present in haematite to metallic iron.

Reducing Agents in the Blast Furnace:
In the blast furnace, carbon monoxide (CO) and carbon (C) act as reducing agents. The reducing agents react with the iron oxide in haematite to remove oxygen and convert it into elemental iron. The overall chemical reaction is as follows:

Fe2O3 + 3CO → 2Fe + 3CO2

Effectiveness of Reducing Agents at Different Temperatures:

a) At Low Temperature:
At low temperatures (below 600°C), carbon monoxide (CO) is more effective as a reducing agent. This is because at low temperatures, the rate of reaction between CO and Fe2O3 is relatively high. The reaction between CO and Fe2O3 is exothermic, meaning it releases heat. This heat helps to maintain the temperature in the blast furnace and provides the energy required for the reduction process.

b) At High Temperature:
At high temperatures (above 600°C), carbon (C) becomes more effective as a reducing agent. This is because at high temperatures, the rate of reaction between carbon and Fe2O3 increases significantly. The reaction between carbon and Fe2O3 is also exothermic, contributing to the heat required for the reduction process.

c) Both Carbon and CO at Any Temperature:
While carbon monoxide (CO) is more effective at low temperatures and carbon (C) is more effective at high temperatures, both agents can still react with Fe2O3 at any temperature. However, their effectiveness may vary depending on the temperature and the availability of each agent in the blast furnace.

d) Carbon at Low Temperature and CO at High Temperature:
The correct answer, option 'A, B', suggests that carbon is effective at low temperatures, while carbon monoxide is more effective at high temperatures. This is consistent with the understanding that the effectiveness of the reducing agents varies with temperature in the blast furnace.

Conclusion:
In the extraction of iron from haematite in a blast furnace, both carbon monoxide (CO) and carbon (C) act as reducing agents. Carbon monoxide is more effective at low temperatures, while carbon becomes more effective at high temperatures. The choice of the most effective reducing agent depends on the temperature conditions inside the blast furnace.