(61e) Systematic Investigation of Segregated Layer Inversion in Liquid-Fluidized Binary Beds

Liquid-fluidized beds of two or more components are encountered in a variety of industrial processes, such as mineral ore dressing, sorting/classification, coal beneficiation, separation in plastic waste recycling and in some biochemical reactors. Depending on the application, segregation may be a desirable or undesirable feature in the process. In some cases, size-driven or density-driven segregation occurs separately or one of them strongly prevails over the other, making predictions obtained using simple models rather reliable. When the solids to separate exhibit contrasting differences in size and density (like in many examples cited above), even the direction of segregation is not easily predictable, i.e. which one component tends to separate towards the surface and which one to sink to the bottom, giving rise for some systems to the so-called “layer inversion phenomenon.”

In the present contribution, the reliability of a recently introduced model for predicting the segregation direction of fluidized binary beds (the Particle Segregation Model, PSM) is examined by systematic experimental investigation of binary beds with different size and density ratios and at different bed composition. The experimentally obtained surface concentration, expansion properties and the layer inversion voidage are compared with the PSM predictions, offering a direct means of model validation.