Comparative Study on the Kinetics of the Isothermal Reduction of Iron Ore Composite Pellets Using Coke, Charcoal, and Biomass as Reducing Agents

Abstract

The kinetics of the isothermal reduction of iron ore–coke, iron ore–charcoal, and iron ore–biomass (straw) composite pellets were studied at 900–1200 °C. Compared with the other two composite pellets, the composite pellet using biomass as a reducing agent showed a more rapid reduction rate at a relatively low temperature. With an increase in the temperature, the reduction rates of the three different composite pellets tended to be equal. The reducing reactions of the three different composite pellets were all mainly controlled by gasification diffusion. The reduction rates can be described by the interface reaction kinetic model ([1−(1−m)1/3]2=kt). The apparent activation energies of the gasification diffusion of coke, charcoal, and biomass composite pellets at 900–1200 °C were calculated using the Arrhenius equation, and they were 95.81, 71.67, and 58.69 kJ/mol, respectively. The biomass composite pellets exhibited a lower apparent activation energy than the composite pellets with other reduction agents.