Model for the final decarburisation of the steel bath through a self-bubbling effect

Abstract

The decarburisation in the basic oxygen furnace is certainly the chemical process ruling the conversion of pig iron into steel and for the production of high deep drawability steel s. At the end of conversion, the steelmakers have often to blow again to achieve the targeted low values of carbon concentration. This further blowing process implies a productivity loss, even it is not strictly needed because the self-bubbling of the metal bath due to the CO formation can allow setting the carbon concentration within the required chemical range. Actually, due to the high temperatures and oxygen activity at the end of the blowing process, the decarburisation process keeps moving up to the equilibrium. The present study describes and validates a chemical-physical model based on thermodynamic and kinetic aspects that allow the steelmakers to forecast when exploiting the self-bubbling phenomenon avoiding the re-blow, increasing the productivity and the refractories working life.