Iron and steel industries are one of the most important infrastructural industries of countries. In last decades, novel methods have attracted attentions to optimize industrial processes due to problems in traditional iron production methods and processes. One of these methods is Direct Reduction Process. In this method, Iron ore is reduced by a set of heterogeneous solid-gas chemical reactions in direct contact with coal. In these reactions, iron oxides are converted at different steps from Hematite to Magnetite, Magnetite to Wustite, and from Wustite to Iron. Most researchers have introduced one-dimensional mathematical models to predict reduction processes. In this study, an unsteady three-dimensional model for a cylindrical packed bed, with solving traort equations and implementation of necessary modules by coding in ANSYS FLUENT, is presented. Chemical mechanism of reduction processes such as iron oxides reduction by hydrogen and carbon monoxide, evaporation and condensation, coal devolatilization, together with their chemical kinetics, are considered thoroughly. Properties and features of solid and gas species are taken into account. In addition, equations related to chemical and physical properties and their variations with temperature are implemented in modelling to enhance accuracy of predictions. Effective conduction heat transfer coefficient is an important parameter in packed bed’s temperature distribution. Therefore, for samples with pure Hematite, different relations for effective conduction heat transfer coefficient are studied, results are compared with experimental data, and the best relation with the least error has been selected. One of the technologies which uses direct reduction to reduce iron, is FASTMET. In this process, iron metallization is done in a rotary hearth furnace. A 3D rotary hearth furnace and the combustion of its eight perimeter burners has been simulated in a steady state condition. Moving from the ceiling of the furnace to the hearth, the velocity of flow has been decreased. This reduction in velocity provides the required reducing atmosphere by maintaining reducing gases above the pellets’ bed. It is shown that in the discharging zone, the flow velocity and temperature have the maxium values. These values are proper for reaching the complete metallization of pellets in the final stage. Key words: Direct Reduction Process, Modelling, Chemical Kinetics, Rotary Hearth Furnace, Combustion.
