Reduction Kinetics of Cement-bonded Natural Ilmenite Pellets with Hydrogen.

Abstract

The hydrogen reduction kinetics of ilmenite was studied thermogravimetrically from I 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. Thereduction 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', which mainly constitute the overall reduction of preoxidized iimenite pellets, were determined separately. Theexperimental data of the reduction of unoxidized pellets were interpreted in terms of a modified one-interface kinetic modei derived from the aforementioned two-interface kinetic mode[, Diffusion of gaseous species through product layer and i ntrinsic chemical reaction were found to be the main rate controlling factors during reduction.