Question

Which of the following conditions is/are favorable for producing low-silicon hot metal in blast furnace ironmaking?

• A. Reduced raceway adiabatic flame temperature
• B. Oxygen-enriched blast
• C. Lime injection through tuyeres
• D. Increased hearth temperature

Hint:

To reduce the silicon content in hot metal, conditions that lower temperature and improve slag formation, like reduced raceway temperature and lime injection, are beneficial.

Answer 1

The Correct Option is A, C

To produce low-silicon hot metal in blast furnace ironmaking, several conditions need to be optimized, particularly those that affect the reduction reactions, the formation of silicates, and the temperature control inside the furnace. Let's go over each option:
Step 1: Analysis of the options - Option (A): "Reduced raceway adiabatic flame temperature" - Correct: A lower raceway flame temperature helps reduce the formation of silicon and silicon oxides, which leads to the production of low-silicon hot metal. A lower flame temperature reduces the degree of silicon reduction during the process.
- Option (B): "Oxygen-enriched blast" - Incorrect: An oxygen-enriched blast typically increases the temperature in the furnace and promotes the reduction of iron. However, it may also increase the silicon content in the hot metal due to higher temperature conditions and enhanced reduction reactions. Therefore, this is not favorable for producing low-silicon hot metal.
- Option (C): "Lime injection through tuyeres" - Correct: The injection of lime helps control the slag chemistry by increasing the amount of calcium silicate, which can capture silicon as it forms. This is beneficial in reducing the silicon content in the hot metal. Lime injection is a key technique to lower the silicon content in the ironmaking process.
- Option (D): "Increased hearth temperature" - Incorrect: Increasing the hearth temperature generally increases the reduction of silicon and other impurities, leading to higher silicon content in the hot metal. Therefore, this condition is not favorable for producing low-silicon hot metal.
Step 2: Conclusion The conditions that are favorable for producing low-silicon hot metal are reduced raceway adiabatic flame temperature (Option A) and lime injection through tuyeres (Option C). Hence, the correct answer is Option A and C.