Thermodynamic and Kinetic Aspects of Sulfur Evaporation from Fe–C Alloy Droplets

Abstract

Evaporative loss of sulfur from Fe-C-0.1 mass% S alloys was investigated using electromagnetic levitation. An inert atmosphere was maintained with a constant flow of purified argon. The influence of carbon concentration, up to carbon saturation, on the reaction kinetics was determined at 1 873 K. The effect of carbon on the activity coefficient of sulfur in liquid iron was also evaluated. While the value for the first order interaction parameter was found to be in good agreement with data in the literature, the value for the second order parameter was higher than those measured using a conventional crucible approach involving gas dissolution into liquid iron. The results are consistent with the premise that sulfur loss is primarily due to the evolution of monatomic sulfur vapor.

Evaporation of S from Liquid Fe–C–S Alloy

“…According to the Eq. (8), the overall rate constant and normalized overall rate constant can also be derived as: values are in favorable agreement with those reported by Wu et al 10) Therefore, it can be concluded that the present kinetic model for S evaporation in liquid Fe-C-S alloy is able to represent the effect of C on the S evaporation.…”

“…Increasing evaporation rate of S by C was attributed to the fact that 1) C increases activity coefficient of S, and 2) C forms volatile carbosulfide species. The latter is consistent with the proposal of Belton et al 13) Contrary to the approach by Wu et al, 10) thermodynamically consistent interaction parameters were used in the present study which were taken from the present authors' CALPHAD type thermodynamic modeling of Fe-C-S system.…”

“…k S R was also estimated by fitting reported data of S evaporation in Fe-S alloy, which was reported by Jung et al ). 10) However, during the evaluation of their work, it was found that two experimental data set from Wu et al 10) and Jung et al 7) were not consistent each other. Figure 3 shows the reported experimental data from these two studies for similar C content 10) (open symbols).…”

“…Almost at the same time, another interesting investigation was carried out by Wu et al 10) They investigated evaporation of S in liquid Fe-C-S alloys at 1 873 K of various C content, at approximately similar S content ([pct S] 0 = 0.1-0.14). Both studies 7,10) employed very similar technique (electromagnetic levitation under flowing Ar gas of the same flow rate).…”

“…Both studies 7,10) employed very similar technique (electromagnetic levitation under flowing Ar gas of the same flow rate). Therefore, these two independent investigations may be used in order to understand evaporation mechanism of S in liquid Fe-C-S alloys of various C and S content, at least at 1 873 K. In the present article, these two experimental research results were carefully analyzed in order to develop a model equation for S evaporation in liquid Fe-C-S alloys.…”