Abstract: The twostage drying and shrinking core model were used to build a kinetic drying model on the basis of research of heat and mass transfer phenomenon. The heat and mass changes together with hot wind direction changing were also considered in this model. Furthermore， the key parameters were recognized with field data， and the simulation curves showed that the models well described the processes of moisture evaporation， dry pellets oxidation and heat exchange of outer air. Based on the kinetic models， hardness models for dry and preheated pellets were also proposed. The comparison results showed that the model was efficient and the realistic drying and oxidation process was well reflected. It also provided a foundation of accurate control and optimization for iron ore pellet drying and oxidation process which has practical significance.

Key words: drying and oxidation process, Gratekiln system, two stage, shrinking core model, kinetic modeling