Gangue content in iron ore used for sintering process is increasing year after year. It results in increasing the energy consumption of ironmaking, if these are used directly. The utilization of magnetite concentrate as iron source for sinter process is one of the methods to resolve this problem because its gangue content is very low. Furthermore, the oxidation reaction of magnetite with oxygen is exothermic. It leads to decreasing amounts of coke agglomerating agent in sinter and decreasing carbon dioxide emissions. However, the production rate decreases by the utilization of magnetite concentrate because the fine size distribution leads to decreasing permeability in the sinter bed. And, increasing the utilization amount of magnetite leads to lowering of the sinter property such as reducibility since the ratio of bivalent iron ions in sinter increases. In this study, effect of coke and CaO in the sinter bed on the oxidation behavior of magnetite is examined to discuss the optimum quasi-particles state in the sinter bed. Using TG, the oxidation rate of magnetite concentrate with and without the addition of coke breeze and CaCO_3 was measured in air at 1473 K. The oxidation rate of magnetite decreased with increasing coke ratio, and the final oxidation ratio also decreased. The reason is that iron oxide reacts with ash compounds in coke and the melted slag with low melting point forms. The CaO addition also leads to the same results. It is suggested that magnetite should be kept away from coke and CaO source in the sinter bed.
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