Abstract

Gas-solid fluidized bed is an effective dry method for beneficiation of −6mm fine coal, belonging to Geldart D particle. Due to the density difference of concentrates and gangue in the raw coal, the bed can remove gangue through segregation of binary particles. The core problem is how to reduce the bubble coalescence and improve segregation degree in the bed. In this study, glass beads and plastic beads were selected to simulate high-density and low-density particles in pulsed gas-solid bed (PGFB). And different pulsation frequencies (f = 0–7 Hz) and gas velocities (N = 1.1–1.7) were selected in this work. The results showed that gas velocity and pulsation frequency played important role on particle segregation and mixing behavior. The segregation index reached the maximum value at pulsation frequency f = 3.49 Hz and gas velocity N = 1.3 when h = 80 mm, indicating pulsed gas-solid fluidized bed can effectively separate particles of different densities. With the increase of bed height, the standard deviation of separation index decreases, and the optimal frequency moves to the low frequency region. This work provides guidance for the study of segregation and mixing behavior of Geldart D binary particles in pulsed fluidized bed.

摘要

气固流化床是一种有效的-6mm细煤干法选矿方法，属于Geldart D颗粒。由于原煤中精矿和矸石的密度不同，床层可以通过二元颗粒的分离来去除矸石。核心问题是如何减少气泡聚结，提高床层的离析度。在这项研究中，选择玻璃珠和塑料珠来模拟脉冲气固床 (PGFB) 中的高密度和低密度颗粒。以及不同的脉动频率（f  = 0-7 Hz）和气体速度（N = 1.1-1.7）在这项工作中被选中。结果表明，气体速度和脉动频率对颗粒的分离和混合行为有重要影响。分离指数在脉动频率f  =3.49 Hz、气速N  =1.3、h =80 mm时达到最大值 ，表明脉冲气固流化床可以有效分离不同密度的颗粒。随着床高的增加，分离指数的标准差减小，最优频率向低频区移动。该工作为研究Geldart D二元颗粒在脉冲流化床中的离析和混合行为提供了指导。