Cohesive interparticle forces and bulk flow properties in fluidisation and powder flow: is a coordinated view possible and convenient?

Binary cohesive interparticle forces are often used to describe the aggregative behaviour of particles in gas fluidization applications of fine powders and, sometime, to explain other phenomena in fluidization such as the delayed bubbling in aeratable powders. These forces, however, can be theoretically estimated but can be hardly measured. The direct measurement of bulk flow properties is a common procedure to predict the powder flow in silos and piles. Rumpf and Molerus suggest some approaches to relate interparticle cohesive forces with bulk properties. In theory, therefore, it would be possible to use the measurement of bulk flow properties to estimate interparticle forces in order to predict the aggregative behaviour of particles in fluidized systems. In this presentation some recent experimental results will be reported trying to demonstrate the direct relationship between bulk flow properties and the aggregative behaviour of cohesive powders in vibrated fluidization and aerated discharge of solids. Other experiments will be also reported to validate the possibility of using the Rumpf approach to relate cohesive interparticle forces to the measurement of bulk flow properties