INFLUENCE OF SULFUR ON INTERFACIAL REACTION-KINETICS IN DECARBURIZATION OF LIQUID-IRON BY CARBON-DIOXIDE

The kinetics of decarburization of continuously carbon-saturated liquid iron by CO2 have been studied between 1280 and 1600‡C at sulfur concentrations between 0.01 and 1 wt pct. The results are consistent with a surface blockage mechanism by chemisorbed sulfur which shows an essentially ideal adsorption isotherm. The adsorption coefficient of sulfur, in (wt pct)-1, is given by the equation log K = 3600/T + 0.57 for carbon-saturated alloys. A small residual rate at apparent surface saturation is observed. This leaves about 1.4 pct of the active surface sites available for reaction, essentially independent of temperature. Studies with varying carbon concentration suggest that to a first approximation, and above about 3 wt pct C, the adsorption equilibrium for sulfur depends only on the thermodynamic activity of sulfur. © 1978 American Society for Metals and The Metallurgical Society of AIME.