Heat transfer and chemical reaction models for reduction of iron oxide pellets in countercurrent moving bed reactors

Mass, energy and pressure balances are performed in a volume slice of a HyL III reactor in order to build a mathematical simulator for the different reduction steps. Three iron ore feed mixtures were simulated finding, in general, good agreement between plant data for metallization of DRI and the corresponding mathematical simulations. The main differences between these two types of data are explained as a consequence of the low efficiency of the contact between the reducing gases, H₂ and CO, and the bed of solids due to the formation of clusters in the different ore feeds. This tendency observes a remarkable increase with rise of the total iron content in the ore feed. The existence of clusters promotes fluid flow malfunctions affecting the uniformity of the DRI quality expressed as it final metallization. This leads to the need of a 3D simulator which should be able to quantify this effect. Finally it was found, in the present research, that carbon monoxide plays a minor role in the dynamic behaviour of the reduction for the feed mixtures analyzed with the mathematical simulator.