Bessemer converter operation — interpreting the white flame During basic or acid Bessemer conversion of hot metal, the flame observed at the converter mouth changes character as refining proceeds. The appearance of a strong white flame generally indicates that silicon and manganese have been largely oxidized and that oxidation of carbon has begun. Evaluate this statement.

Introduction / Context:
In the Bessemer process, hot metal is refined by blowing air through tuyeres. The flame at the mouth gives visual cues correlating with oxidation stages. Operators historically relied on flame color and intensity to judge progress before modern sensors.

Given Data / Assumptions:

• Hot metal contains C, Si, Mn, P, and other impurities.
• Blow sequence: rapid oxidation of Si and Mn, followed by intense carbon oxidation (“carbon boil”).
• Observation: flame color and brightness change with gas composition and temperature.

Concept / Approach:
Silicon and manganese oxidize early, raising bath temperature and forming silica and manganese oxide slags. As carbon oxidation accelerates, large volumes of carbon monoxide burn at the mouth, producing a bright, whitish flame. This “white flame” traditionally marks the onset and progression of the carbon blow. Toward the end, the flame drops when carbon is depleted.

Step-by-Step Solution:

Verification / Alternative check:
Historic operating manuals correlate photometric flame intensity with bath carbon content; modern practice uses off-gas analysis confirming CO/CO2 spikes during carbon oxidation.

Why Other Options Are Wrong:

• “Disagree” or “signals end of blow”: flame drop, not peak whiteness, signals endpoint.
• “Only in acid lining”: the flame behavior is tied to off-gas, not solely to lining chemistry.
• “Only after iron oxidation”: bulk Fe oxidation is not the intended stage indicator.

Common Pitfalls:
Confusing early orange/yellow flames with the intense white carbon blow; ignoring that final flame collapse indicates nearing completion.

Final Answer: