ABSTRACT
The defining parameter of gravity classification is currently held to be the final settling velocity of particles of boundary grain size. However, results of an experimental and theoretical study of a multi-fraction solid phase show that the physics of the process is not determined exclusively by the interaction between individual solid particles and the flow and that energy exchange during collisions among particles has a significant effect on the results of separation. It was demonstrated that the structure of the flow is determined mainly by the geometry of the channel and that the lifting power is a composite of the flow’s action on a certain narrow size class and the action of particles belonging to other narrow size classes. Thus both the continuous medium and the individual fractions share in the formation of the dispersoid. In turn, the dispersoid influences the behavior of the particles in each fraction. Hence the need to consider a “differentiated” dispersoid that is distinct for the particles of each size class. Basic computational formulas for the process of gravity classification were worked out using the results of these studies and their conformity to the experimental data was demonstrated.
