Segregation and mixing behavior of geldart D binary particles in pulsed gas-solid fluidized bed

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.