Equilibrium between FeO-MnO-Al₂O₃ Slags and Molten Iron

Abstract

The experimental work on the equilibrium between molten iron and FeO-MnO-Al₂O₃ slags at 1560°C has been carried out to determine the activities of the constituent oxides.
In the range of liquid slag composition, the activity of iron oxide shows positive deviation from ideality, which is increased with increasing alumina contents and attains to maximum at about 50mol% FeO composition regardless of alumina contents.
On the other hand, the activity of manganous oxide shows a progressive slight increase in negative deviation from the ideal solution law as the slag composition increases in alumina or manganous oxide contents.
Isoactivity diagram of the constituent oxides for the FeO-MnO-Al₂O₃ slags and isoconcentration diagram for the molten iron in equilibrium with those slags are established by the calculation based on DARKEN'S quadratic formalism and experimental data.
A statistical mechanical treatment is applied to derive the thermodynamic behavior of the FeOMnO-Al₂O₃ slags and the results are compared with those obtained by the same treatment for FeOMnO-SiO₂ system.