Dephosphorization rate of high carbon iron melts by CaO-based slags

The oxidation rates of phosphorus in high carbon iron melts were examined at 1400°C by using CaO-based slags such as LD slag and Calcium Ferrite (CF) type slag. The results were analyzed with the coupled reaction model. Although, little phosphorus was initially oxidized by the addition of LD slag alone, the degree of dephosphorization was considerably improved by adding further FeO to LD slag. This improvement can be explained by the increase in oxygen activity at the slag-metal interface and mass transfer coefficient. The degree of dephosphorization by CF type slags was higher than that by LD slag. Among them, the degree of the dephosphorization by a mixture of CaO or CaCO₃ and Fe₂O₃ was higher than that by CF sintered. The phosphorus distribution ratio and the CaO efficiency for dephosphorization by CF type slags were compared with those by slags containing CaF₂ or CaCl₂. As a result (or As a conclusion) it was expected for CF type slags to be the effective flux for the dephosphorization in practical operation.