Effect of particle size, shape and density differences on binary mixture segregation during blast furnace charging

  • Roeplal, Raïsa (TU Delft)
  • Pang, Yusong (TU Delft)
  • Schott, Dingena (TU Delft)

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A blast furnace is a counter-current reactor which produces liquid iron through a series of chemical reactions occurring between ascending hot reduction gas, which is injected through nozzles at the bottom of the furnace, and a descending packed bed consisting of different raw materials (the “burden”) which are charged at the furnace top. Bed permeability is a crucial factor in furnace efficiency which depends on the burden distribution which is achieved through charging. It is well known that segregation is likely to occur during charging since the material mixture contains particles differing simultaneously in size, shape and density. However, predicting how the burden will be distributed is particularly difficult due to the combined effect of these differences. The Discrete Element Method has been used extensively to gain understanding of the prevalent segregation mechanisms during charging and the resulting burden distribution. So far, researchers have focused mostly on investigating size segregation [1] [2] [3] [4] [5] [6] while the effect of density difference has hardly been studied [7], and the effect of particle shape has not yet been considered. A few works modelled mixtures of particles differing in both size and density [8] [9] [10], however, fundamental understanding of how size and density differences contribute to the final burden distribution is still lacking. In this work, we systematically investigate the effects of size, shape and density differences on mixture segregation by means of a full-factorial design. We first consider the effects of these material properties separately and subsequently investigate combined effects on burden distribution. The novelty of this work is that, for the first time, we investigate the importance of all three material properties as well as their interactions on mixture segregation. These findings provide insight on how segregation can be mitigated when charging different kinds of mixtures to the furnace.