Separation Process of Fine Coals by Ultrasonic Vibration Gas-Solid Fluidized Bed

Abstract

Ultrasonic vibration gas-solid fluidized bed was proposed and introduced to separate fine coals (0.5–0.125 mm fraction). Several technological methods such as XRF, XRD, XPS, and EPMA were used to study the composition of heavy products to evaluate the separation effect. Results show that the ultrasonic vibration force field strengthens the particle separation process based on density when the vibration frequency is 35 kHz and the fluidization number is 1.8. The ash difference between the light and heavy products and the recovery of combustible material obtain the maximum values of 47.30% and 89.59%, respectively. The sulfur content of the heavy product reaches the maximum value of 6.78%. Chemical state analysis of sulfur shows that organic sulfur (-C-S-), sulfate-sulfur (-SO4), and pyrite-sulfur (-S2) are confirmed in the original coal and heavy product. Organic sulfur (-C-S-) is mainly concentrated in the light product, and pyrite-sulfur (-S2) is significantly enriched in the heavy product. The element composition, phase composition, backscatter imagery, and surface distribution of elements for heavy product show concentration of high-density minerals including pyrite, quartz, and kaolinite. Some harmful elements such as F, Pb, and As are also concentrated in the heavy product.

Conventional and recent advances in gravity separation technologies for coal cleaning: A systematic and critical review

“…The experimental results of many researchers showed that superficial air velocity was the major parameter affecting the separation [ [231] , [232] , [233] , [234] , [235] ], followed by vibration (i.e., amplitude [ 230 , 231 , 233 , 234 ] and frequency [ 230 , 231 , [233] , [234] , [235] ]) and other parameters (i.e., feed rate [ 236 ] and separation time [ 230 ]) while bed height did not significantly affect the separation [ 231 , 234 ] (Table S3). Recently, ultrasonic vibration gas-solid fluidized bed was developed to separate coal and high-density impurities like pyrite, quartz, and kaolinite using ultrasonic vibration force field [ 237 ].…”