In this study, the mechanism of reduction of hematite-magnetite concentrate (HMC) by graphite-calcium carbonate reductant mixture at about 1000 C was investigated. The initial and middle stages of the reduction process (up to 63 pct) were mainly aected by the heat transfer inside the crucible. It was concluded that in the middle to nal stages of the reduction process, the gaseous diusion of reducing gas to the FeO-Fe reaction interface and the carbon gasication are the mixed controlling mechanism. The reduction rate was relatively slow below the carbon gasication temperature. According to X-ray diractometer (XRD) analysis, the formation of the metallic iron was not observed before the carbon gasication. The scanning electron micrographs showed the formation of iron whiskers in the outer layer of the sample, which resulted in swelling of the sample. The observation of the reduced samples’ sections showed that the reduction progress was topochemical. The progress of the reduction from the inner surface of the sample was insignicant compared to the reduction from the outer.

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