Dynamic simulation of pellet induration process in straight-grate system

A mathematical model of pellet induration process in the straight-grate system is presented. The important physical and chemical phenomena known to affect the heat and mass transfer in the process have been taken into account in the formulation of the model. These include heat transfer between gas and pellet, gas flow, evaporation and condensation of moisture, oxidation of magnetite, combustion of coke breeze, calcination of lime and dolomite, and shrinkage of pellet and pellet bed slump. The model is validated by comparing its predictions against actual measurements in an industrial scale plant as well as a pilot pot grate. The effect of several process parameters on the induration regime are evaluated using the model. It is demonstrated through a case study that the model can be employed as a valuable tool for such purposes as process optimization and design of the induration machine.