Sorting in Gas Fluidised Beds

Publication Reference: 
Author Last Name: 
Prof K Leschonski
Report Type: 
Research Area: 
Powder Flow
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Complementary to the already existing surveys offered by myself to IFPRI on "Air Classification" and the "Sorting by Sieving and Air Classification" a third survey report has been prepared on "Sorting in Gas Fluidised Beds". Sorting in a fluidised bed may be achieved either in a counterflow or a crossflow sorting machine. The present report describes in detail the relevant theoretical background necessary for the precalculation of a fluidised bed sorting process. Most of it belonging to the standard theories used in fluidised bed reactor design. It was clearly found, that the existing theories describing the behaviour of a fluidised bed with respect to changes in the size distribution of the particles forming the bed, their shape or the influence of the void ratio is inadequate and needs further theoretical and ex- perimental consideration. The precalculation of a fluidised bed used for sorting furthermore suffers from the fact, that the settling behaviour of the heavy that is the sink product cannot be described accurately enough. This is mainly due to the fact, that the influence of the above mentioned variables on the apparent density of the fluidised bed is not very well known. Therefore in actual practice bench scale experiments must yield the relevant data. Bench scale experiments have been performed with four different bed materials and several different materials to be sorted. The last part of the report summarises equipment as invented and suggested in the literature for the sorting in gas fluidised beds. This report finalises my work in classification and sorting.