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%.