Thermal stress in iron-ore pellets with differentiated porosity

The thermal stresses in three types of iron-ore pellets with differentiated porosity are compared. The thermal stress of pellets obtained by the spraying of wet batch onto the batch coating and onto pelletized materials is analyzed. The influence of the porosity and thermal mass of the pellets on the thermal-stress distribution over the pellet cross section is determined. The variation in the strength of pellets with differentiated porosity over the cross section is assessed in the presence of a dynamic temperature field over the porous sphere. The role of the thermal mass in the core and shell of the pellet is also evaluated. The action of thermal stress in activating the sintering of iron-ore pellets is analyzed. Recommendations for improving the thermal conditions in pellet roasting are outlined. The best pore structure is obtained by forced nucleation of pellets, which results in elevated porosity in the core.