A steel converter is a primary steelmaking furnace used to convert molten iron (hot metal) into steel by blowing oxygen to remove excess carbon and impurities.
In modern steel plants, the steel converter most commonly refers to the Basic Oxygen Furnace (BOF), also called the Basic Oxygen Converter (BOC) or LD converter.
What Does a Steel Converter Do?
The main function of a steel converter is to refine hot metal by:
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Reducing carbon content
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Removing impurities such as silicon (Si), manganese (Mn), phosphorus (P), and sulfur (S)
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Adjusting steel composition to meet target specifications
This is achieved through high-speed oxygen blowing, which causes oxidation reactions that generate heat and refine the metal.
Main Types of Steel Converters
1. Basic Oxygen Furnace (BOF / LD Converter)
Most widely used worldwide
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Uses 99.5% pure oxygen
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Oxygen is blown onto molten iron through a water-cooled lance
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Steelmaking time: 15–20 minutes per heat
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Produces large volumes of steel efficiently
Typical charge:
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70–85% hot metal
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15–30% scrap steel
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Fluxes (lime, dolomite)
2. Bottom-Blown or Combined-Blown Converter
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Oxygen or inert gas blown from the bottom and/or top
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Improved bath stirring
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Better control of chemical reactions
Key Components of a Steel Converter
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Converter vessel (steel shell)
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Refractory lining (mainly magnesia-carbon bricks)
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Oxygen lance
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Tilting mechanism
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Slag door and tapping spout
Typical Operating Conditions
| Parameter | Range |
|---|---|
| Temperature | 1,600–1,700 °C |
| Carbon after refining | 0.03–0.1% |
| Heat size | 50–300+ tons |
Why Refractory Lining Is Critical
Steel converters operate under:
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Extreme temperatures
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High oxygen activity
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Highly basic, FeO-rich slag
Therefore, magnesia-carbon bricks are used in:
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Slag line
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Barrel
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Impact and tapping zones
They provide:
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Excellent slag resistance
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High thermal shock resistance
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Long service life
In One Sentence
A steel converter is a high-temperature furnace—most commonly a Basic Oxygen Furnace (BOF)—that converts molten iron into steel by blowing oxygen to remove carbon and impurities efficiently.
