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How does basic oxygen steelmaking convert blast-furnace iron and scrap into steel?
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iron processing
Iron ore is one of the most abundant elements on Earth, and one of its primary uses is in the production of steel. When combined with carbon, iron changes character completely and becomes the alloy steel.
Basic oxygen steelmaking (BOP) is a highly efficient process that converts a charge of liquid blast-furnace iron and scrap metal into steel using pure oxygen.12
The process typically follows these steps:
- Charging: A basic oxygen furnace (BOF)—a refractory-lined, tiltable vessel—is charged with approximately 70–75 percent molten iron and 25–30 percent scrap metal, along with lime and other fluxes. The scrap is essential to absorb the intense heat generated during the reaction, preventing the molten steel from reaching temperatures too high for casting.23
- Oxygen Blow: A water-cooled lance is lowered into the furnace to inject pure oxygen at supersonic velocities. This triggers rapid, exothermic (heat-releasing) oxidation of impurities such as carbon, silicon, phosphorus, and manganese.12
- Refining: The duration of the oxygen blow, usually around 20 minutes, is carefully controlled to reduce carbon to the desired level.12
- Tapping: Once refined, the liquid steel is tapped into a ladle, where ferroalloys and deoxidizers are added to achieve the final required composition.2