DESIGN AND MODELLING OF FINAL STEEL DECARBURATION PROCEDURE THROUGH SELF-BUBBLING EFFECT

Within the context of the Basic Oxygen Furnace (BOF), the decrease of the carbon concentration is certainly the chemical process ruling the conversion of pig iron into steel and to produce steel featured by a significant attitude to the deep drawing. At the end of the oxygen blowing and after the fulfilling of the chemical analysis the steelmakers have often to blow again to achieve the targeted low values of carbon concentration. The further blowing process implies a productivity loss and it is not usually 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 without a further oxygen blowing. Actually, due to the high temperatures and the value of the oxygen activity at the end of the blowing process, the decarburization process keeps moving up to the equilibrium. The present study describes and validates a thermodynamic-kinetic model that allow the steelmakers to forecast when the working conditions can avoid blowing again, thus exploiting the self-bubbling phenomenon. This action can increase the productivity and the working life of the refractories.