Decreasing the carbon dioxide emission from steel industries is an important issue. It is considered that due to the high reactivity of carbon iron ore composite, it can control the thermal reserve zone temperature and decrease the consumption of reducing agents in blast furnace. In the present study, a reaction model of the carbon iron ore composite based on a lumped system is proposed to analyze the reduction behavior in the blast furnace. This model is composed of several reaction steps between carbon, iron ore, and gas phase. The carbon solution loss reaction rate of the small particles of reducing agents is determined by the thermogravimetric method. It is found that the gasification of reducing agents is the rate-determining step in the reduction of the carbon iron ore composite. Accordingly, the particle size and reactivity of reducing agents such as coke have an influence on the reduction rate of the carbon iron ore composite. The influence of the gas composition in the atmosphere around the composite on the reduction is analyzed by using the reaction model. Moreover, the reduction behavior of the carbon iron ore composite in the blast furnace is quantitatively examined by comparison of reduction degree and gas composition change in order to investigate the reduction mechanism of reducing agents.
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