New Insights into Powder Flowability

By Reg Freeman
Published in Innovations in Food Technology - December 2001

In recent years technological advances have enabled the close definition of the physical
properties of many materials, yet experts in the food industry accept that characterising the flow behaviour of powders is still a significant challenge. While much has been written about the theoretical aspects of powder behaviour, anyone involved in the development, formulation or manufacture of products that have constituents in powder form at some stage of processing, will be aware of the high degree of variability exhibited by these materials. Familiar processing problems include the adhesion of cohesive materials to containing surfaces, excessive aeration of powders in pneumatic transport systems, the bridging of powders in hoppers, electrostatic charging of materials during handling, and the consolidation of powders during transportation and storage. Managing these requires an understanding of powder flowability that until now has come mostly from experience. Developments in powder rheometry now offer better and easier characterisation of powders, providing the information necessary to optimise handling conditions and to bring improvements in processing efficiency.