Localized heating and reduction of magnetite ore with coal in composite pellets using microwave irradiation

Magnetite iron ore-coal composite pellets were microwave irradiated in N-2, atmosphere with a power supply gradually increased in 2 min intervals from 0.2 up to 2kW at 2.45GHz. Electron probe microanalysis (EPMA), X-ray image of SEM micrographs, back scattered electron image (BSE) and Fe, O, S and C mappings of composite pellets irradiated up to different temperatures were obtained. Under the present experimental conditions, pellets heated up to about 800 degrees C without reduction. Above this temperature the reduction occurred stepwise, Fe3O4 reduced to FeO between about 800 degrees C and 1000 degrees C and then FeO reduced to Fe from about 1000 to 1250 degrees C average temperatures. The measured temperature appears to reasonable represent the average temperature of the pellet. However inside of the reacting mass localized slightly different temperatures may exist. Point carbon contents of reduced iron inside the composite pellet irradiated up to 1150 degrees C were from almost 0% to 2% with no correlation between with their spatial location inside the pellet. It is concluded that carbon in the microwave irradiated pellet acting as a reducing and heating agent at the same time generates localized reduction microenvironments.