Oxidation of magnetite

The oxidation of large octahedral single crystals of magnetite extracted from chlorite shale at Shabrovsk talc mine (Middle Urals) is experimentally studied. Differential heating curves show that the processes occurring in the oxidative roasting of magnetite (Fe₃O₄) are highly reproducible. The mechanism of martensite oxidation is considered, as well as the temperature ranges corresponding to exothermal and endothermal reactions. The thermal effect of martensite oxidation is determined from that of a standard (CaCO₃) and the areas under the differential heating curves on the corresponding thermograms. Those areas are proportional to the thermal effect. The results obtained are of considerable interest: knowing the temperature range of martensite oxidation, the heat sources in the various technological zones of the conveyer roasting machines may be taken into account in establishing the roasting conditions, thereby optimizing the thermal conditions and reducing the fuel consumption.