Study on the separation mechanism of coal and gangue particles during coal slime classification in a hydrocyclone

The precise classification of coal slime containing lots of ultrafine particles provides appropriate size range of feed for subsequent sorting. In this study, experiments are performed to investigate the classification performance of coal slime. Both high-density gangue and low-density coal are considered in simulating the multicomponent system of coal slime. The misplacement of fine particles in the underflow is mainly caused by -0.045 mm fine gangue component. The enrichment ratio of -0.045 mm gangue is much larger than that of -0.045 mm coal in the underflow due to its higher density. The adverse effect of particle density on classification can be reduced by increasing feed concentration appropriately. Multiphase flow pattern, theoretical force analysis, and particle trajectory are applied to reveal the migration mechanism of the coal and gangue components. This work will give insights into the migration mechanism of multi-component particles during the classification of coal slime.