Simulations of a multicomponent mixture in the reflux classifier todemonstrate the effect of dispersion coefficient on its internal state

In this study, influence of the dispersion coefficient on the internal state of a multicomponent mixture comprising 35 types of particle species with five different sizes ranging -2.0+0.25 mm and seven different densities, 1400 to 2000 kg/m3, in a reflux classifier under continuous process conditions is presented. Simulations were performed to study the effect of dispersion coefficient on the separation density, D50, separation efficiency, Ep, and solid volume fraction of the multicomponent mixture. The simulation results provided a good agreement with the published experimental results of the reflux classifier, operated at full scale in 2005, for a relatively high value of the dispersion coefficient, 0.0030 m2/s, and a relatively small value of the dispersion, 0.00030 m2/s, in the fluidization and inclined sections of the device, respectively. Moreover, different fixed values of the dispersion coefficient and a published proposed model of the dispersion coefficient were incorporated in the model to examine variations in the system and were compared with the validated simulation results. It was found that the selected values of the dispersion coefficient had not much effect on the $D_{50}$ values. However, the Ep values changed significantly with changes in the dispersion coefficient values. The smaller values of the dispersion coefficient provided lower values of the Ep that did not match well with the validated simulation results. Furthermore, the variations in the total solid volume fraction within the reflux classifier for different values of the dispersion coefficient has been demonstrated.