Chuncheng Liang

The Effect of Fine Coal Particles on the Performance of Gas–Solid Fluidized Beds

The distribution of 3 × 1 mm fine coal particles across the fluidized bed was analyzed during beneficiation of coal in a gas–solid fluidized-bed separator. The effect of accumulation of the fine coal on the bed performance was also studied. The experimental results show that as 3 × 1 mm size fine coal content increases in the solid medium the mean density of bed decreases linearly. A mathematical model was developed that can predict the standard deviation of the bed density. The bed density increases sharply as the coal-fines content exceeds 4.5 weight%, at which point the bed becomes unstable and poor fluidization performance takes place. Furthermore, the separation performance of a bed was measured by 50 × 6 mm size tracker balls. The separation performance decreased gradually as the fine coal particles accumulated. When the content of the bed reached 4.5 weight%, the probable error, E, rose from 0.05–0.08 g/cm3. Therefore, to maintain good fluidization and separation performance the 3 × 1 mm fine coal content of the medium should be controlled to less than 4.5% during dry beneficiation processing of coal.

Industrial Application of a Modularized Dry-Coal-Beneficiation Technique Based on a Novel Air Dense Medium Fluidized Bed

ABSTRACT Coal is one of the most important primary energy sources all over the world. One of the clean-coal technologies is coal preparation, and dry-coal beneficiation plays an increasingly important role with an increasing shortage of water. A novel air dense medium fluidized bed (ADMFB) separator developed by the China University of Mining and Technology, with magnetic powder and fine coal acting as the heavy medium, has the advantages of uniform and stable bed density, low cost, and high reliability. The world’s first modularized dry-coal beneficiation based on the novel ADMFB was established, realizing the industrial application of ADMFB separation technology. The industrial application showed that the ash content of coal decreased to 3.46% with an ash rejection of 85.57%, the yield of clean coal was 67.88%, the probable error (E value) was 0.055 g/cm3, the organic efficiency was 93%, and the heavy-medium loss when separating one ton of coal was 0.42 kg. Less than

Fluidization Characteristics of a Fine Magnetite Powder Fluidized Bed for Density-Based Dry Separation of Coal

2 was spent for separating one ton of raw coal.

Experimental and numerical simulation studies of the fluidization characteristics of a separating gas–solid fluidized bed

Gas-solid fluidized bed separation technique is very beneficial for saving water resources and for the clean utilization of coal resource. The hydrodynamics of 0.15–0.06 mm fine Geldart B magnetite powder were experimentally and numerically studied to decrease the lower size limit. The results show that the static bed height should be controlled near 300 mm (e.g., 300–350 mm). The bubble size, amount, and frequency of the fine particle bed are smaller than those of the bed containing 0.3–0.15 mm large Geldart B particles, thus leading to a higher bed activity. The pressure drop and density of the fine particle bed are uniform and stable, which indicates a good fluidization quality. Furthermore, simulated results are consistent with experimental data, which indicates the correctness and effectiveness of the simulations. The superficial gas velocity should be adjusted to not more than 1.8U mf for the fine particle bed. Additionally, wide size range magnetite powder, which contains 94.23 wt% < 0.3 mm particles with a 0.3–0.06 mm particles content of 91.38 wt%, was used in an industrial scale modularized demonstration system for 50-6 mm coal density separation. The ash content of feed coal was reduced from 55.35% to 14.67% with a probable error, E, value of 0.06 g/cm3.