Question

In blast furnace, the highest temperature is in

• A. reduction zone
• B. slag zone
• C. fusion zone
• D. combustion zone

Hint:

Combustion zone = hottest region in blast furnace.

Answer 1

The Correct Option is D

To understand where the highest temperature occurs within a blast furnace, we first need to examine the different zones present inside this installation. A blast furnace is typically divided into several zones, each characterized by different chemical reactions and temperature ranges:

1. Combustion Zone: Also known as the "hearth" or "bosh" zone, this is the area where coke burns in the presence of hot air (oxygen rich) blown in through tuyeres. This zone is responsible for reaching the highest temperatures in a blast furnace, typically in the range of 1900°C to 2300°C. The high temperature is essential for the reduction and melting processes in subsequent zones.
2. Fusion Zone: This zone exists above the combustion zone. It's where the reduced iron melts and flows. The temperatures here are quite high, but not higher than those in the combustion zone.
3. Slag Zone: This is where impurities, mainly silica and alumina, form slag. Although hot, it's not as hot as the combustion zone.
4. Reduction Zone: This is where iron oxides are reduced to iron by carbon monoxide generated in the lower zones. The temperature here varies and decreases as you move upwards in the furnace.

From the above explanation, it is evident that the combustion zone reaches the highest temperatures within the blast furnace because this is where the primary combustion of coke occurs, generating intense heat that is necessary for the smelting process. The correct answer is thus the combustion zone.