1979 Volume 65 Issue 12 Pages 1692-1701
The effects of some foreign oxides on the rate limiting step of the reduction of pellets from wustite to metallic iron and the values of rate parameters are studied.
It is confirmed that the reduction behavior of those pellets is represented by an unreacted core model or an uniform reaction model depending on the kinds of foreign oxides and iron oxides as starting materials. The mixed rate control equation of mass transfer in the gas phase, intraparticle gas diffusion, and chemical reaction can be applied to any iron oxide containing CaO and hematite and magnetite containing Al2O3. On the other hand, the reduction rate of the pure iron oxides, wustite containing Al2O3 and any iron oxides containing MgO is controlled by the oxygen diffusion in the metallic iron shell.
These results are suggested by the conclusion of our previous studies that wustite grains are reduced nontopochemically and pellets are reduced topochemically when those complex oxides consisting of iron oxides and any foreign oxide precipitate in wustite during reduction.