Mesoscale numerical simulation of the multiple step reaction in hydrogen reduction of iron oxides

This work designed a mesoscale method of multi-step reduction of Fe2O3 with H-2 based on Lattice Gas Cellular Automata (LGCA). Particles in the LGCA were marked to distinguish all the reactants, intermediates, products, and inert. A self-organized evolutionary mechanism is designed. The hydrogen reduction of Fe2O3 in the temperature range of 460-550 degrees C and 650-800 degrees C was simulated. Results show that the intermediate product Fe3O4 was found in both conditions, and its mass fraction quickly reach a peak at similar to 0.8 and gradually decrease thereafter. An "induction period" can be identified in the initial stage of the reaction at 650-800 degrees C, where the reduction rate is slow due to the hindered formation of FeO. The porosity inside the Fe2O3 particles increases continuously through the reduction process, resulting in significant changes in the flow field around the particles. Consequently, the wake vortex gradually decreases and disappears eventually.