Isothermal reduction kinetics of the mixture of iron carbon agglomerates and sinter

Abstract

The effect of iron carbon agglomerates (ICA) on the reduction of sinter is very important to blast furnace (BF) ironmaking. In this paper, the isothermal reduction kinetics of ICA-sinters mixture and the coupling synergistic mechanism between ICA and sinter are comprehensively studied. The results show that the early stage of isothermal reduction of ICA-sinters mixture is jointly controlled by the interfacial chemical reactions of FeO being reduced to Fe in sinter and gasification reaction in ICA, and the later stage is controlled by the internal diffusion. As the reactivity of ICA improves from 52.81% to 69.71%, the isothermal reduction reaction activation energy of ICA-sinters mixture decreases from 84.22 to 72.58 kJ/mol in early stage and decreases from 110.78 to 97.41 kJ/mol in late stage. Meanwhile, the activation energy of isothermal reduction reaction for the mixture of ICA and sinter with a higher reducibility is lower. There is a coupling synergistic effect between ICA and sinters, and ICA plays a continuous role in circulating CO and transferring oxygen during the reduction of sinter, which can significantly promote the reduction of iron oxides in sinter. The synergistic effect gradually increases with the improvement of the reactivity of ICA and the reducibility of sinter.