Dependence of Temperature and Slag Composition on Dephosphorization at the First Deslagging in BOF Steelmaking Process

Abstract

Abstract Effects of temperature and slag composition on dephosphorization in a 120 ton top-bottom combined blown converter steelmaking process by double slag method were studied. The slag properties were determined by scanning electron microscope- energy dispersive spectrometry (SEM-EDS), X-ray diffraction (XRD). The results show that the transition oxidation temperature between dephosphorization and decarbonization T f is not the favorable temperature for the first deslagging. The optimum first deslagging temperature is confirmed to be approximately 1,673 K which is about 70 K higher than T f . High melting temperatures phases (such as 3CaO·SiO 2 ) in the slag with high basicity and MgO content are unfavorable to the dephosphorization. The optimum process condition for dephosphorization at the first deslagging in present work is approximately 1,673 K in temperature, 2.0 in slag basicity, 6 and 17 mass% in MgO and T.Fe content, 6 mass% ≤ MnO content.