Carbothermal reduction of iron ore applying microwave energy

Abstract

This paper presents the results of a study on carbothermal reduction of iron ore made under the microwave field in equipment specially developed for this purpose. The equipment allows the control of radiated and reflected microwave power, and therefore measures the microwave energy actually applied to the load in the reduction process. It also allows performing energy balances and determining the reaction rate with high levels of confidence by simultaneously measuring temperature and mass of the material upon reduction with high reproducibility. We used a microwave generator of 2.45GHz with variable power up to 3000W. Self-reducing pellets under argon atmosphere, containing iron ore and petroleum coke, with 3.5g of mass and 15mm of diameter were declined. We obtained the kinetic curves of reduction of iron ore and of energy consumption to the process in the maximum electric field, in the maximum magnetic field and at different values of power/mass. The data allow analyzing how the microwave energy was actually consumed in the reduction of ore. Composite pellets of iron ore and carbon were subjected to microwave radiation and the amount of microwave energy absorbed during carbothermal reduction was measured. Although only a fraction of the incident radiation is absorbed, it is possible to heat the pellet and complete the reduction reaction at rates that can be competitive to conventional heating. Copyright © 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.