Influence of bubbles on the segregated stability of fine coal in a vibrated dense medium gas–solid fluidized bed

[Display omitted] •The evolution characteristics of bubbles in the separation process was studied.•The influence of bubble movement on the separation stability of fine coal was investigated.•The separation effect of raw coal was quantitatively analyzed by the solids mixing entropy. In this paper, the variation of bubble size and number in the separation process of vibrated fluidized bed as well as the influence of bubble movement on the axial distribution of fine coal in different positions of the bed were studied. The result revealed that the size and number of bubbles is correlated with the fine coal separation effect in the separation process. When the bed is in a uniform and stable fluidized state, the size of bubbles in the separation process was in the range of 1–2.5cm and the number of bubbles was reduced by nearly 50%, which is helpful to promote the stratification and segregation of fine coal. Thereby, after separation, the ash content of refined coal products of anthracite and 1/3 coking coal was reduced to 12.1% and 23.7% respectively, and the content of refined coal was up to 42.5% and 68.5% respectively, which show that the vibrated fluidized bed has a good separation performance, and can separate efficiently the coal of size −6+1mm.