Burden distribution plays an important role in achieving stable and efficient operation in a modern ironmaking blast furnace. In this process, burden materials are charged and distributed to the throat region, and further affect gas distribution and blast furnace performance. In this work, a model based on discrete element method is established. In particular, the surface properties of spherical particles are first justified in terms of angle of repose aiming to reflect the effect of particle shape. The proper values of sliding friction and rolling friction coefficients for different burden materials are then recommended. Burden trajectories from the rotating chute and burden layers formed at the throat region are compared with physical experiments, showing consistent results. The effects of some key variables such as chute angle and friction coefficients are also examined. The results indicate that burden trajectories are not sensitive to sliding and rolling friction coefficients. But those variables should be properly set to obtain reasonable burden layer profiles.

HYUNSIK PARK, IL SOHN, JOHN TSALAPATIS, and VEENA SAHAJWALLA High-temperature behavior of magnetite-coke composite pellet fluxed with dolomite was investigated by customized thermogravimetric analyzer (TGA) at 1573 K (1300°C). The overall reaction was influenced by C/O ratio and dolomite content. The reduction was accelerated by increased amount of dolomite, while the samples with higher C/O ratio showed the improved reduction degree. X-ray diffraction (XRD) pattern of reduced pellet showed the phase changes of the iron oxides. Noticeable iron peaks were observed when the sample reached the final stage of reduction. CO and CO 2 gases released from the reaction were measured by Infrared (IR) gas analyzer. Relation between enhanced reducibility of pellets and larger CO gas evolution from the Boudouard reaction was confirmed from the analysis. Compressive strengths were studied for the practical assessment of reduced pellets. Samples with low-reduction degree showed better physical property. Excessive amount of dolomite also deteriorated the integrity of pellets.

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