2000 Volume 40 Issue 4 Pages 315-321
The kinetics of several gas–metal reactions relevant to bath smelting have been investigated. The rate of carburization of liguid iron by C2H6 gas was measured between 1400 and 1600°C under conditions in which partial pressure of C2H6 was in the range of 0.016 to 0.04 atm and sulfur content in the iron was in the range of 0.003 to 0.5 wt%. The experimental results indicate that the rate is controlled by the dissociation of C2H6 on the surface of iron and gas phase mass transfer in series. The gas phase mass transfer can be corrected with reasonable accuracy and the chemical rate constants were obtained. The rate was retarded by sulfur in liquid iron and there was evidence of a large residual rate at high sulfur contents. The rate of carburization of pure liquid iron (as=0.01) by CH4 –CO2 gas mixture was measured at 1600°C under conditions at which the rate is controlled by gas phase mass transfer and chemical reaction in series. The gas was 6% CH4 and up to 2.5% CO2 in Ar. It was concluded that CH4 and CO2 reached the surface of the iron before they reacted with each other and carburization by CH4 and decarburization by CO2 occurred independently for the present experimental conditions. The rate of decarburization of carbon saturated liquid iron by CO–CO2 –O2 gas mixture was measured at 1600°C. The partial pressure of O2 in 90%CO/10%CO2 gas was in the range of 0 to 0.03 atm and sulfur content in the metal was 0.1 wt%. The measured rate shows that the gases reached the surface of metal before they reacted with each other and decarburization by CO2 and O2 proceeded independently at a high gas flow rate (5l/min), but there may have been some gas phase reaction at lower flow rate (2l/min).