Application of a 2D segregation-dispersion model to describe binary and multi-component size classification in a Reflux Classifier

Abstract

A 2D segregation-dispersion model was utilized to study the transport mechanism of particle species in the Reflux Classifier (RC) with a wide channel spacing. The main objective was to study size classification and describe the internal state of the system under continuous process conditions with changing variables such as fluidization velocity, underflow rate and solids throughput. Moreover, the Richardson and Zaki hindered settling model was incorporated into the 2D model to study the separation of particle species based on differences in their settling velocities. A set of simulations was performed for binary and multicomponent mixtures, having a density equal to 2490 kg/m3 in both cases. For the binary mixture, particle species of size 200 and 300 µm were used, while for the multicomponent mixture eight particle species with sizes between 49 and 421 µm were selected. The partition curves obtained from the model predictions were successfully validated with published experimental results. The separation performance of the RC was characterised by analysing how the imperfection and the d50 values changed with the process variables. Furthermore, the simulation data were used for the first time to demonstrate the concentration distribution of the individual solid particle species in the fluidization and inclined sections of the RC. This study showed that the particle species with sizes closer to the d50 values had a larger presence in both the vertical and inclined sections of the RC. Thus, the total concentration inside the RC mainly consisted of those particle species.