Improvement of Reactivity of Carbon Iron Ore Composite with Biomass Char for Blast Furnace

Abstract

Enhancement of reactivity of the burden in the blast furnace can decrease the reducing agent of blast furnace. Besides high reactivity coke, the carbon iron ore composite is considered to be a typical high reactivity burden that can control the thermal reserve zone temperature. Since the reactivity of biomass char is much higher than that of coke, the use of carbon iron ore composite with biomass char will be favorable for decreasing the reducing agent. In the present study the reaction and reducing behavior of the carbon iron ore composite with biomass char were investigated. The gasification rate of biomass char was measured in CO2 atmosphere, and the reaction rate equation of that was derived. The microscopic structure change of biomass during carbonization was experimentally analyzed. According to the experimental results, the reduction of the composite begins at about 550°C in an inert gas atmosphere, and it is much lower than the composite with coke. Analysis of the reaction of carbon iron ore composite was carried out with the reaction model of the carbon iron ore composite based on a lumped system, in which the reaction rate of biomass char and iron ore were installed. The reaction model shows that the biomass char can improve the reduction behavior of the carbon iron ore composite especially in the lower temperature region. Moreover, the influence of gas atmosphere and the optimum structure of the composite were investigated by the model calculation to estimate the optimum condition of the composite in the blast furnace.