Rate of Oxidation of Liquid Iron by Pure Oxygen

Abstract

The rate of oxidation of liquid iron by oxygen gas has been studied using a volume constant technique.
The process of oxidation consists of two stages of very rapid oxidation in the early stage and relatively slow oxidation in the second stage after the formation of iron oxide covering the surface of melt. The rate of the dissolution of oxygen into the melt was studied under the presence of three phases of gas, liquid oxide, and liquid iron to make clear the mechanism of oxidation.
From the experimental results obtained, it was considered that the rate-etermining step under the co-existence of three phases was the transport of solute gas through the stagnant layer in the oxide phase at the gasoxide interface. This mechanism is supported by the following experimental facts: a) The rate of oxidation is proportional to the square root of oxygen pressure in the gas phase. b) The reaction rate decreases with decreasing the stirring of the melt. c) The rate is not influenced by the amount of oxygen and sulphur in liquid iron.
The apprarent activation energy of the reaction is low, giving a value of 5 kcal/mol.