Iron grain growth kinetics during carbothermic reduction of ilmenite concentrates with microwaves

The iron grain growth kinetics during the carbothermic reduction of ilmenite concentrates in the microwave field were investigated and described by using iron grain size d(t) and a parameter (attenuation voltage U) of microwave-absorbing characteristics. The results demonstrated that there was a linear relationship between ln d(t) and 1/T during the iron grain growth, and the kinetic model equation for the iron grain growth in the microwave field was deduced as: ln ; the activation energy of the iron grain growth at the initial stage and the late stage in the microwave field were calculated to be 31.04 and 69 kJ/mol. It was found that there was also a linear relationship between ln U and 1/T. The iron grain growth described by using the attenuation voltage (U) of microwave-absorbing characteristics and the grain size d(t) had the same rule, the activation energy at initial stage was small and became big at the late stage. The results suggested that the iron grain growth could be described by using a parameter of microwave-absorbing characteristics during the carbothermic reduction of ilmenite concentrates in the microwave field, if ignored the specific values of the activation energy, just used the changing trends of the activation energy, which could help us utilize the microwave technology in the ilmenite concentrate processing and the recovery of the byproducts of metallic iron.