(331e) Powders With Class: Beyond Fluidization

Fluidization in the context of industrial practice involves the deliberate and controlled aeration of a body of particulate solids, and the Geldart classification provides general insights into the behaviour of these fluidized solids, on the basis of their density and size. There are many other situations, both in industry and in nature, where bulk particle-fluid contact and interaction take place, or are caused to take place, and not surprisingly, the Geldart Classification offers a potentially useful frame of reference for the behaviour of such systems. 

Included in the presentation will be a look at pneumatic conveying where the Geldart classification first found application outside fluidization and still endures as a useful indicator of suitability for dense phase or other conveying modes, and consideration of the behaviour of particulate materials in rotating drums, where powders from different groups display distinctly different avalanching behaviour. Also, I will give a brief account of an industrial case study where the work of Derek Geldart facilitated the quantification and explanation of a problem involving the handling and transport of a material with a wide size distribution, and finally the talk will visit the natural world.