Fluidization characteristics and fine coal separation in a gas-solid vibrated fluidized bed

The paper presents a vibration separation fluidized bed through introducing the vibration energy into a gas-solid fluidized bed and the pulverized coal and magnetite powder were mixed as a binary composite heavy medium solids.The micro-differential pressure sensors were used to collect the bed pressure signal online,and the signal time-frequency analysis method was used to decompose the signal.The fluidization behavior characteristics in the separation process of the vibration fluidized bed and the effect of vibration energy on the fluidization quality of separation fluidized bed were analyzed from microcosmic viewpoint.In addition,the energy characteristics of bed pressure signal was utilized to study the response of pressure fluctuation and different fluidization phenomena.Based on the research of 6-1 mm fine coal separation experimental results,combined with the evolution characteristic of bubble behavior in the bed,the evaluation method of particle mixing entropy was put forward for the analysis of the separation efficiency of fine coal beneficiation,meanwhile,the separation characteristics of 6-1 mm fine coal in vibrated fluidized bed and the effect of bubble movement on the separation and stratification of fine coal were studied.The results show that the energy of pressure drop signal caused by bubbles increases firstly and then decreases with the increase of gas velocity,and increases gradually with the increase of the amplitude and frequency.However,the total energy of bed pressure drop signal increases with the increase of the gas velocity,vibration frequency and amplitude.In addition,the separation degree of two components is determined by the particle mixing entropy of clean coal and gangue.It is found that with the increase of the gas velocity,the change trend of particle mixing entropy decreases firstly and then increases.With the increase of the vibration frequency and amplitude,the particle mixing entropy of clean coal and gangue increases gradually.Moreover,under the optimal conditions which are vibration amplitude A=2 mm,vibration frequency f=20 Hz and gas velocity v=12 cm/s,the energy of bed pressure fluctuation and particle mixing entropy are the lowest with stable bed pressure drop fluctuation and uniform bed density distribution.Moreover,the separation performance of 6-1 mm fine coal is the best with the separation accuracy value,E=0.095 g/cm3 and the ash content of clean coal is 9.59%.