The Rate of Oxidation of Phosphorus and Silicon in Liquid Iron by Molten Slags

Abstract

The rates of oxidation of phosphorus and silicon in liquid iron by steelmaking-type slags were examined at temperatures from 1 540 to 1 670°C in an induction furnace. The results obtained were analyzed on the basis of a coupled reaction model.
The results showed that the silicon in the iron was rapidly oxidized after the slag addition, and the content of silicon decreased below 0.01% within one minute. A part of phosphorus was oxidized together with the oxidation of silicon. Thereafter, the dephosphorization of liquid iron occurred gradually.
The kinetic analysis showed that the value of apparent mass transfer coefficient in the slag, k_sρ_s, , was calculated to be 0.0027 to 0.0061 g/cm²s when the value in the liquid iron, k_mρ_m was given as 0.36 to 0.47 g/cm²s. When the values of overall mass transfer coefficients, K_P and K_Si, were calculated from the above data by the equations (5) and (7), respectively, it was found that the silicon transfer was controlled mainly by the diffusion step in the metal, while the transport in the slag played an important role for the phosphorus transfer.