Carbothermic Reduction of Alumina at 1823 K: On the Role of Molten Iron and Reaction Mechanisms

Abstract

A possible reaction mechanism is presented for the low temperature carbothermic reduction of alumina in the presence of molten iron under inert conditions. This reduction was found to take place in a number of stages that involved the carburization of molten iron, disintegration of alumina into sub-oxide gases, reduction of these gases by the solute carbon followed by the capture of reduced aluminum by molten iron due to its high affinity. With increasing levels of aluminum in the iron, the wettability of alumina with molten metal undergoes a transition from poor wetting (with Fe) to good wetting (with Fe–Al–C) leading to the dissolution and subsequent reduction of alumina in the Fe–Al–C melt. These reaction steps were observed to occur in Al₂O₃–Fe₂O₃–C system at 1823 K and atmospheric pressure.