Bessemer converter operation — meaning of the red flame During the blowing process in a Bessemer converter, the appearance of a bright red flame typically indicates that:

Introduction / Context:
The Bessemer process refines molten pig iron into steel by blowing air through the bath. Observing the flame at the mouth of the converter offers real-time cues about which impurities are being oxidized. Students should correlate flame appearance with the sequence of chemical reactions.

Given Data / Assumptions:

• Typical acid Bessemer practice on low-phosphorus iron.
• Common oxidation sequence: silicon and manganese first, followed by carbon.
• Operators monitor flame characteristics to time the blow.

Concept / Approach:
When air is blown, the most readily oxidized elements burn first. Silicon and manganese oxidize early, producing slags and a flame that then changes character. The bright red or luminous flame associated with carbon monoxide burning indicates that carbon oxidation has begun in earnest after Si and Mn have largely been removed. The intensity of the flame helps determine the endpoint.

Step-by-Step Solution:
At blow start: Si and Mn oxidize preferentially.As these diminish, carbon begins to oxidize, producing CO that burns at the mouth with a bright flame.The red or vivid flame thus signals carbon removal phase.Therefore, select the option stating Si and Mn are burned out and carbon oxidation has started.

Verification / Alternative check:
Classic metallurgical descriptions of converter practice correlate the flame rise and fall with the carbon removal curve, confirming the interpretation.

Why Other Options Are Wrong:

• Air burning out silicon and manganese: this occurs earlier before the red flame surge.
• Immediate tilt to pour: pouring is timed after the carbon blowdown endpoint, not simply at first red flame.
• No red flame: contrary to observed practice.
• Phosphorus removal: acid Bessemer does not remove phosphorus effectively.

Common Pitfalls:
Confusing the initial oxidation stage with the carbon monoxide flame stage; the latter marks carbon oxidation, not Si/Mn removal.

Final Answer:
silicon and manganese have been removed and carbon oxidation has started