干旱区生态环境知识资源中心

Experimental and simulation approaches were combined to investigate the fluidization characteristics of a dense-medium gas-solid fluidized bed (DMGFB) for coal cleaning. Results indicated that the static bed height should be adjusted by maintaining a stable height of 150-300 mm to avoid its harmful effect on fluidization stability. Bed pressure drops presented favorable stability with slight fluctuations at a superficial gas velocity of 11.68 cm/s (1.6 U-mf). The uniform density distributions with slight variations throughout the whole bed were verified by comparing the experimental, simulated and calculated results. A fluidization index, U-mb/U-mf, was used to conduct stability-region analysis for DMGFB. On the basis of fluidization stability, a successive beneficiation flowsheet via a DMGFB separator was used to perform density-based separation of 6-50 mm sized run-of-mine coal. Results demonstrated that the low-ash clean coal with a yield of 61.36% was efficiently obtained with the ash content reduced from 39.64% to 10.18% and sulfur content rejected from 1.36% to 0.85%. Probable error E values were 0.06 and 0.075 g/cm(3) in high- and low-density separation stages, indicating efficient separation performance. The dry coal beneficiation technique has great potential for utilization in arid and water-deficient areas and countries. (C) 2015 Taiwan Institute of Chemical Engineers. Published by Elsevier B.V. All rights reserved.