Kinetics of MgO Reduction in CaO-Al 2 O 3 -MgO Slag by Al in Liquid Fe

摘要

Kinetics analysis without fully taking into account the effect of mass transport in slag phase on MgO reduction by Al in liquid steel would lead to overestimation of Mg pickup by steel and driving force of the reaction. Two rate models considering mass transport in (a) steel melt phase only (single control model) and (b) steel and slag melt phases (mixed control model) were developed for evaluating the thermodynamic equilibria between CaO-Al 2 O 3 -MgO slags and Al-killed steels. Calculated results from the two models were compared and then validated by equilibrium experiments between a CaO-Al 2 O 3 -MgO slag (Al 2 O 3 -saturated) and Al-killed steels with different Al levels at 1873 K (1600 °C). Results showed that the calculated reaction rate in the mixed control model was always lower than that in the single control model due to the slow mass transport in the slag phase. The mass transfer coefficient of [Mg] in the steel was computed to be 6.2 × 10 ?5 m/s from the equilibrium experiment results between an Fe-1.0 mass% Al steel and 51 mass% CaO-39 mass% Al 2 O 3 -10 mass% MgO slag at 1873 K (1600 °C), with which the mixed control model was validated at different initial Al levels in the steels.