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:

In blast furnace operation, high temperature favors silicon pickup. To reduce silicon, lower the flame temperature, enrich the blast with oxygen, and add lime to trap silica.

Answer 1

The Correct Option is A, B, C

Step 1: General concept.
Silicon in hot metal mainly comes from reduction of silica in coke ash. This reduction is more favorable at high temperatures. To reduce silicon pickup, the process should reduce the effective high temperature and capture silica before it enters the hot metal. Step 2: Check each option.
- (A) Reduced flame temperature decreases silica reduction. Correct.
- (B) Oxygen enrichment improves efficiency and lowers coke rate. This shortens the high temperature zone and reduces silicon. Correct.
- (C) Lime injection increases basicity and captures silica as slag, preventing its entry into hot metal. Correct.
- (D) Increased hearth temperature promotes more silicon dissolution, which is unfavorable. Wrong.
Step 3: Conclusion.
The favorable conditions are (A), (B), and (C). \[ \boxed{\text{Correct: (A), (B), and (C)}} \]