The GATE Grind

GATE 2025 MT – Question 27

Mineral Processing and Extractive Metallurgy · Ironmaking · 1 mark · Multiple select

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

  1. Reduced raceway adiabatic flame temperature
  2. Oxygen-enriched blast
  3. Lime injection through tuyeres
  4. Increased hearth temperature

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Show answer and explanation

Correct answer: (A) Reduced raceway adiabatic flame temperature; (C) Lime injection through tuyeres

Explanation

Lower raceway temperature suppresses silicon reduction/SiO generation and therefore lowers silicon pickup. Lime injection binds silica and lowers its activity, also reducing silicon transfer to metal. Oxygen enrichment and increased hearth temperature tend to promote silicon reduction. Hence **A,C**.