Drying and Roasting Characteristics of Iron Ore Pellets with Microwave Heating

Drying and roasting behavior of iron ore pellets with microwave and conventional heating have been comparably investigated. The results showed that the dehydration time of green pellets can be shortened by approximately two-thirds with microwave heating. Meanwhile, the average compressive strength of pellets with organic binders dried by microwave heating reached 40 N, which was four times that obtained by conventional heating. Mechanism research indicated that the microwaves heated moisture selectively and resulted in the rapid dehydration of the green pellets at a relatively lower temperature. Therefore, the organic binder in the green pellets remained unharmed and functioned as strength holder for the dried pellets. Moreover, sintered pellets with an average compressive strength of 1600 N can be obtained by microwave heating, which was superior to that of conventional heating (800 N). Microwave heating was proven to improve the oxidation of magnetite and the crystallization of newly formed hematite grains during the pellet-roasting process.