DESIGN AND MODELLING OF A NEW VALUABLE OPERATIVE PRACTICE FOR PHOSPHORUS REMOVAL IN LD CONVERTER

In the primary ironmaking production process, the use of iron ores featured by a high concentration of the chemical elements affecting detrimentally the mechanical properties (i.e. phosphorus) leads to a greater difficulty to manage the refining period of the hot metal by the Basic Oxygen Furnace (BOF). High initial phosphorus concentration in the hot metal (0.08-0.11 %wt.) results in operative practice troubles for achieving a final P concentration lower than 0.015 %wt. In this context, the conventional oxygen blowing patterns developed for low phosphorus pig iron cannot be used anymore for steels characterized by deep drawing attitude and/or high toughness requirements. In this study, a kinetic-thermodynamic model for dephosphorization is proposed and a more efficient dephosphorization procedure of the hot metal in LD converters (350 t) have been developed, able to reach a final P concentration at the end point lower than 0.015 %wt.