煤炭气固流态化干法分选是干旱缺水及高寒地区细粒煤分选提质、矿物加工以及固废资源化的重要途径，工业应用潜力大。目前，用于分选的流化床已有较多研究，其基础理论研究也较为深入，研究领域包括流化床的形成、流化床空气动力学以及流化床流动模型与模拟等，但干法重介质流化床的低密度分选技术和密度调节范围仍待完善。加重质的合理选择对干法重介质流化床选煤具有重要意义,其与流化床干法选煤系统的净化回收流程、分选机的操作参数及分选效果密切相关。采用干法重介质流化床对二元加重质单一组分、窄粒级、宽粒级以及三元加重质在流化床中的流化特性进行研究，对比分析磁铁矿粉、硼铁矿粉流化特性、膨胀率与粒度的关系。试验结果表明，磁铁矿粉和硼铁矿粉均能达到良好的流化状态。随加重质粒度的减小，起始流化气速显著降低，膨胀性能逐渐增强。与150～125 μm硼铁矿粉和74～45 μm磁铁矿粉混合相比，125～74 μm硼铁矿粉与74～45 μm磁铁矿粉混合后的床层压降波动较大。300～74 μm粒级硼铁矿粉与74～45 μm粒级磁铁矿粉在9种不同质量配比下，床层压降均无明显波动。随加重质粒度的减小，膨胀性能逐渐增强；窄粒级二元加重质混合均匀程度随硼铁矿粉含量的增加而提高；宽粒级二元加重质混合时，稳定流化后的流化曲线随细粒级的增多而波动加剧，难以形成稳定的分选环境；随着煤粉含量增加，三元加重质的流化效果逐渐变差。为保证流化床床层密度较好的均匀稳定性，三元加重质中煤粉含量不宜超过15%。

Coal gas-solid fluidized dry separation is an important and effective way for fine-grained coal separation to improve quality,mineral processing and solid waste recycling in arid and water-scarce regions and alpine regions,and it has great industrial application potential. At present,the fluidized bed used for separation has been studied by many researchers. The basic theory has been studied in depth,including the formation of fluidized bed,fluidized bed aerodynamics,fluidized bed flow model and simulation,etc. However,the low-density separation technology and density adjustment range of dry dense medium fluidized bed still need to be improved. The reasonable selection of dense medium is of great significance to the coal preparation of dry dense medium fluidized bed. It is closely related to the purification and recovery process of the fluidized bed dry coal preparation system,the operation parameters of the separator and the separation effect. A self-made fluidized bed was used to study the fluidization of single component,narrow particle size and wide particle size in two-element dense medium,and the fluidization characteristics of three-element dense medium in a fluidized bed were studied. The fluidization characteristics,expansion rate and particle size of magnetite powder and paigeite powder were compared and analyzed. The results show that both magnetite powder and paigeite powder can reach good fluidized state. With the decrease of dense medium size,the initial fluidized gas velocity decreases significantly,and the expansion property increases gradually. Compared with the mixture of 150-125 μm paigeite powder and 74-45 μm magnetite powder,the bed pressure drop fluctuates more with the mixture of 125-74 μm paigeite powder and 74-45 μm magnetite powder. Under nine different weight ratio conditions,the bed pressure drop of 300-74 μm paigeite powder and 74-45 μm magnetite powder has no obvious fluctuation. With the decrease of the size of dense medium,the expansion property gradually increases. The homogeneity degree of the two-element narrow particle dense medium increases with the increase of the content of paigeite powder. When the two-element wide particle size dense medium is mixed,the approximate horizontal section of the fluidization curve fluctuates more with the increase of fine particles,which is not conducive to form a stable separation environment. With the increase of pulverized coal content,the fluidization effect of ternary dense medium gradually becomes worse. In order to ensure good uniform stability of fluidized bed density,the content of pulverized coal in ternary dense medium should not exceed 15%.

0 引言

1 试验

   1.1 分选系统

   1.2 评价指标

2 结果和讨论

   2.1 单一加重质流化特性

   2.2 多元加重质流化特性

   2.3 多元加重质临界流化气速与混合/分离

   2.4 低质煤分选效果

3 结论