Study on Particle–Bubble Interaction and Separation in Fluidized-Bed Flotation

Fluidized-bed flotation can realize effective recovery of coarse minerals. In this study, 1-2 mm lignite was used as the experimental material. First, the interaction between the particle and bubble was investigated to reveal the mechanism of fluidized-bed flotation. The rising water flow makes the particle settling velocity decrease, leading to an increase in the particle-bubble contact time. The application of methyl oleate as a collector for coal leads to a significant reduction in the induction time and an increase in the critical detachment force. Both these conditions contribute to the formation of particle-bubble aggregation, indicating that the decrease in settling velocity and the enhancement of hydrophobicity are significant for the recovery of coarse coal. Subsequently, a comparative analysis of separation efficiency between column flotation and fluidized-bed flotation was performed alongside an investigation into the optimal parameters of fluidized-bed flotation. The clean coal yield of fluidized-bed flotation is more than 30%, while that of column flotation is less than 10%. The combination of fluidized-bed flotation and a methyl oleate collector demonstrates a capacity for efficient recovery of coarse coal particles. When the methyl oleate dosage is 2000 g/t and the superficial water velocity is 87 mm/s, the fluidized-bed flotation achieves the optimum separation effect, with a clean coal yield of 32.71% and an ash content of 9.89%.