Reduction rates of MnO and SiO2 in SiMn slags between 1500 and 1650°C

Abstract

The kinetics of MnO and SiO2 reduction in SiMn slags based on Assmang/Comilog ore and HCFeMn (high-carbon ferromanganese) slag were investigated between 1500 and 1650°C under a CO atmosphere. The results showed that charges containing HCFeMn slag had relatively faster reduction rates than those without. The difference in the driving force for MnO reduction was insignificant among the SiMn slags at 1500°C, which implies a low contribution of the driving force for reduction rate. The slag viscosities were also rather similar, around 1 poise at 1500°C, which could not explain the different reduction rates. Instead, the different charges containing various sulphur contents are believed to give rise to the varying reduction rates. The estimated activation energies for MnO reduction were around 500-920 kJ/mol for charges containing HCFeMn slag, and between 250-300 kJ/mol for those without. Based on the estimated kinetic parameters, the considered rate models were able to describe the reduction of MnO and SiO2 in SiMn slags between 1500 and 1650°C.