Characteristic gas velocity and fluidization quality evaluation of vibrated dense medium fluidized bed for fine coal separation

Abstract In order to remove incombustible impurity minerals, a vibrated dense medium fluidized bed (VDMFB) can be adopted for fine coal dry separation, while Geldart B magnetite powder can serve as the medium. The influence of vibration on characteristic gas velocity in flow pattern transition stage was experimentally investigated at a vibration amplitude range of 0.5–4 mm and frequency range of 5–35 Hz. The experimental results demonstrate that at a low frequency (f  E p ⩽ 0.1 as the evaluation index, a suitable effective operating gas velocity range for coal separation under different vibration parameters is determined. The ratio of the boundary operating gas velocity to U mfc is 0.67–2.28. Thus, a uniform and stable fluidization environment is provided for dry fine coal separation.