The effect of thermodynamics in effective removal of phosphorous in steel making

Numerous research works has been carried out for the removal of phosphorous from the steel since several decade because of its detrimental effect on mechanical properties of steel such as cold shortness temper embrittlement poor ductility and strength. In the present work, dephosphorization experiments have been carried out. Total fifteen heats were processed, experimenting on (0.017%C) low carbon steel. During each individual heat, the samples of slag and liquid metal have been collected. It is found that Rate of dephosphorization is mainly controlled by mass transfer in the slag. Addition of MgO may increase the melting point and viscosity of the slag which decreases the kinetic conditions of dephosphorization. It decreases the activity of CaO and FeO in slag and increase in Al2O3 decreases the viscosity of the melt which have a negative impact on phosphorous removal. The dephosphorization increases with increase in slag basicity and becomes maximum approximately 3, further increase in basicity beyond that has found to have negative impact on phosphorous removal.