REDUCTION KINETICS OF CEMENT-BONDED NATURAL ILMENITE PELLETS WITH HYDROGEN

The hydrogen reduction kinetics of ilmenite was studied thermogravimetrically from 1 073 to 1 273 K with three kinds of cement-bonded natural ilmenite pellets. The kinetic behavior of the reduction of preoxidized ilmenite was researched with the same technique from 973 to 1 273 K. The reduction of the pellets proceeded topochemically, but, the behavior of the grains constituting the pellets was more complex. The reduction kinetics of preoxidized pellets was analyzed according to a two-interface kinetic model and the kinetic parameters of the two main reactions Fe3+ --> Fe2+ and Fe2+ --> Fe-degrees, which mainly constitute the overall reduction of preoxidized ilmenite pellets, were determined separately. The experimental data of the reduction of unoxidized pellets were interpreted in terms of a modified one-interface kinetic model derived from the aforementioned two-interface kinetic model. Diffusion of gaseous species through product layer and intrinsic chemical reaction were found to be the main rate controlling factors during reduction.