Optimization of coal size for beneficiation efficiency promotion in gas–solid fluidized bed

Abstract

With China already committed to peak carbon dioxide emissions before 2030 and aiming at achieving carbon neutrality before 2060, coal separation has recently become a hot research topic, in particular, gas–solid fluidized separation technology has attracted significant research attention. Coal particles with size of +10 mm can be separated efficiently via currently used technologies; nonetheless, specific scientific problems of fine coal separation still need to be systematically explored. In this study, combined with the properties of coal particles, a density model of fine coal in fluidized bed separation process was proposed. The separation effect was found to be better with the increase of feeding coal particle size, in particular, the coal particles with size larger than 5 mm underwent effective separation. The results reveal that the drag force of the fine coal separation process is an important factor restricting the separation efficiency. Fluidization theories, such as pressure drop, gas–solid two-phase model, and particle sedimentation theory could explain that with the decrease in the feeding coal particle size from 10 mm, the probable error E value increases from 0.105 to 0.355 g/cm3, the misplaced material content M increases from 5.48% to 16.13%, and the lower limit of the separation is controlled at 5 mm. This helps to enhance the processing capacity and increase the separation granularity range of the fluidized bed.