Segregation of equal-sized particles of different densities in a vertically vibrated fluidized bed

The present work experimentally studies the influence of vibration and gas velocity on the density-induced segregation of particles in a pseudo-2D vibrated fluidized bed. One half of the particles of the bed are ballotini spheres of density 2500kg/m3 and the other half are heavier ceramic particles of density 4100kg/m3 or 6000kg/m3. Digital Image Analysis is used to characterize the rate and extent of particle mixing with time for different gas velocities, vibration amplitudes and frequencies. The results of the experiments indicate that the vibration strength and the gas velocity have an important effect on both the evolution and the final extent of density-induced particle segregation. It was observed that by introducing vertical vibration to a bed that is fluidized close to minimum fluidization conditions the rate of segregation and the final segregation index of a mixture of light and dense particles is enhanced. However, for vibration strengths greater than a critical value around 3–4, the degree of segregation decreases due to a more vigorous three dimensional mixing of particles in the bed. [Display omitted] •Density segregation is studied experimentally in a vibrated fluidized bed.•Particles of the same size and different density were used as bed material.•A segregation index is proposed to quantify the segregation rate and extent.•Adding vibration close to minimum fluidization conditions enhances segregation.•Vibration strength over a critical value decreases the degree of segregation.