Flow of Non-Homogeneous Particulates in Rotating Drums

Abstract

Numerous industries deal with particulate systems such as the cement, ceramics, chemical, metallurgical and pharmaceutical industries. Usually the particulate systems handled in these industries are non-homogeneous, that is, their constituents are heterogeneous in their physical properties such as particle size, density, particle shape, and surface roughness. Handling of these systems during transport and/or manufacturing is usually associated with movements of these particulates at transfer points, being shaken, moving through drums, or sliding over inclined planes, which leads to the particulate mass being energized or disturbed. Disturbing such non-homogeneous systems results in mutual separation of the particulate constituents as a result of differences in their physical properties. The mutual separation is a natural phenomenon called segregation. In some instances, segregation is desired, while in most cases it is detrimental. Segregation in particulate systems takes place as a result of several forces, mainly frictional and gravitational forces, acting on the individual particles inside the system while it is energized. It is well known that the contributions of these forces in controlling the movement of particles are functions of the physical properties of the constituting components of the system. This paper concerns investigation and discussion of the mechanisms of particulate motion and the role of the forces acting during energizing a particulate system, particularly while moving through rotating drums, and their effects on the quality of the final products of non-homogeneous particulate systems.

Keywords

• segregation
• particulate systems
• flow of non-homogeneous particulates
• rotating drums
• mixing-demixing of particulates
• continuous flow of powders