LABORATORY STUDY ON REDUCTION KINETICS OF IRON ORE PELLETS WITH CO GAS

In order to understand the reducibility of industrial pellets, isothermal reduction experiments were performed by using the thermogravimetry technique at 900-1100 degrees C with 100% CO. The apparent activation energy, reaction rate constant and diffusion coefficient were calculated in terms of the Arrhenius plots and the unreacted core model, respectively, and the rate determining steps were ascertained. The microstructure and iron oxides forms of the pellets at different reduction stages were studied by the FESEM and EDS techniques. The results manifested the determining step of the reaction was the interfacial chemical reaction dining most of the time from the initial stage through the middle and latter stage and shifted to the solid diffusion at the final stage, and that the pellets reduction progressed in the order from higher oxides to lower oxides of iron, which proved the application of the unreacted core model to the kinetics analysis was appropriate.