1992 Volume 32 Issue 9 Pages 953-961
The kinetics of the oxidation of a cement-bonded pellet made of natural ilmenite was studied with an unsteady nonisothermal kinetic model derived by assuming pseudo-steady state mass transfer through the product layer and unsteady state heat transfer within the pellet. The derived model agreed well with the experiments. It was further found that the amount of the heat accumulated inside the pellet during oxidation was too great to be negligible in comparison with that lost to its surroundings, especially, in the initial period. During the oxidation of an ilmenite pellet with pure oxygen, the overall reaction rate was mainly controlled by the intrapellet diffusion of oxygen and the total heat transfer rate was principally limited by the poor heat conduction through the product shell. In the case of the oxidation of the ilmenite pellet with diluted oxygen, it is reasonable to analyze the reacting pellet as an isothermal system provided the oxygen concentration being less than 10 mol%.
