Selectivity of Microwave Energy Consumption in the Reduction of Fe₃O₄ with Carbon Black in Mixed Powder

抄録

In the present work, mixtures of magnetite and carbon black powers were irradiated by a constant microwave power supply of 2.8 kW at 2.45 GHz. The temperature was measured as a function of the irradiation time from 220°C. The progress of the reduction was examined by XRD analyses of reaction products at various temperatures in the range 400–1200°C. Under the present experimental conditions magnetite selectively absorbs microwave energy below approximately 650°C; meanwhile carbon black absorbs it in the whole temperature range. The reduction of magnetite to wustite was observed to occur from at least a measured temperature of 400°C but did not occur homogenously inside the mixture. At 800°C, the reduction of wustite to iron started and occurred almost homogeneously inside the reacting mixture mass.
A general conclusion of this work is that microwaves are absorbed and used in their path within the irradiated mass by the material of highest absorbing microwave power.