Basic Oxygen Furnace

What is a Basic Oxygen Furnace?

A basic oxygen furnace is a tiltable converter used in stainless steel making to transform liquid pig iron and steel scrap into steel. The furnace is a vertical cylindrical vessel, fitted with a water-cooled lance that delivers oxygen at high speeds, oxidising impurities in the metal bath.

How a Basic Oxygen Furnace Works in Stainless Steelmaking

While the BOF is widely used in traditional steelmaking, its role in stainless steel production is more selective and often combined with other processes. In operation, molten pig iron is charged into the furnace along with scrap metal and fluxes such as lime. Oxygen is then blown over the bath through nozzles via the lance for around 20 minutes. This oxidises carbon, silicon, phosphorus, and manganese, generating intense heat and forming slag to capture impurities. 

The process is highly efficient, and each heat charge yields between 30 and 360 tons of stainless steel and completes in less than an hour. The vessel can be tilted to charge materials and to tap molten steel once the refining is complete.

Role of Basic Oxygen Furnace in Stainless Steel Production

Although the BOF is not the primary method for producing stainless steel, it is occasionally used in hybrid routes, especially when Electric Arc Furnaces (EAF) are used to melt stainless steel scrap or pig iron, followed by refining steps. In such cases, the basic oxygen furnace can contribute to carbon reduction and slag formation, but the fine control of alloy content and impurity removal is typically carried out in processes like AOD (Argon Oxygen Decarburisation) and VOD (Vacuum Oxygen Decarburisation).