Mathematical Model for Energy Saving in Induration of Iron Ore Pellets Containing Solid Fuel

Mathematical model for a pilot scale iron ore pellet induration furnace has been developed which considers the process of induration including the reactions of limestone, magnetite and coke. The differential equations of energy, mass and momentum are solved simultaneously. The profiles of temperature, pressure and concentration are obtained. Performing separate experiments on sub processes; drying, firing and cooling have checked the validity of the model. At first, a mixture of iron ore is selected and then the percentage of limestone is changed. The maximum metallization and fired pellet strength with minimum sticking vs. basicity is obtained. In the next stage the percentage of coke in iron ore is altered and all of physical and chemical property of the pellets are measured. Finally, the optimum percentage of coke in the iron ore is determined. By using different percentage of coke in the pellet the experiments are performed in three conditions. In the first condition, inlet gas temperature is decreased alone. In the second condition, inlet gas temperature and total indurtion time are decreased together and in the third condition, in addition to above conditions, oxygen injection to the furnace is carried out. Energy savings in all three conditions have been obtained.