Dissolution rate of solid iron into liquid Fe-C alloy

Abstract

Dissolution rate of solid iron into liquid Fe-C alloy was investigated using a sampling method at a fixed reaction area. The initial carbon concentration of the bulk liquid Fe-C alloy was set as 4.23, 3.29 and 2.17 wt% for the experiments at 1503, 1597, and 1688 K, respectively. The temperature dependence of the rate constant was obtained as follows: $\ln k(m/s) = - 3.47 - \tfrac{{8905}} {T}$. The activation energy was estimated to be 74 kJ/mol. A dimensionless analysis was carried out separately to confirm the rate-determining step. The measured values showed reasonable agreement with the calculated values from the dimensionless analysis. Therefore, it is concluded that the mass transfer in the liquid boundary layer is the rate-determining step for the dissolution of solid iron in the liquid Fe-C alloy. The liquid boundary layer was estimated approximately 100 μm, which slightly decreased with increasing temperature. Present experimental results would be helpful to understand the mechanism of liquid iron formation in the ironmaking and steelmaking processes as well as in the reduction of iron-containing slags.