Effects and optimization of ratio of particle size grading on compaction density of calcined coke particles

Abstract The bulk density of the anodes affects the energy consumption and associated carbon emissions of the calcined anodes over the course of the Hall-Héroult process. The bulk density of the anode mainly depends on the compaction density of calcined coke particles. In this paper, the vibro-compacting process of calcined coke particles is simulated using discrete element method. The particle behavior during vibro-compacting process and the inter-particle contact information with different ratios of particle size grading are investigated. The effects of different ratios of particle size grading on the compaction density and microstructure are studied. The critical average diameter which can distinguish whether the compaction density meets standard requirement is first proposed and obtained. The triangular coordinate graphical is introduced to optimize the ratio of particle size grading which is different from conventional method. The results show that the larger the proportion of coarse particle and medium particle, the more large voids between particles, and the increase of fine particle can effectively fill the inter-particle gap. The critical average diameter of calcined coke particles is 2.26 mm, and average diameter less than 2.26 mm can meet the standard requirement. The optimal ratio of particle size grading is 46% for coarse particle, 12% for medium particle and 42% for fine particle.