Separation of small nonferrous particles using an angular rotary drum eddy-current separator with permanent magnets

The paper presents a method for separating the small metallic nonferrous particles from two component nonferrous mixtures using a new type of dynamic eddy-current separator with permanent magnets. The so called Angular Drum Eddy-Current Separator (ADECS) consists of a horizontal rotary drum covered with permanent magnets, alternately N–S and S–N oriented. The rotor is placed oblique, under the superior part of a horizontal conveyor belt, coplanar with its surface. The axis of the drum and the direction of displacement of the belt make a certain angle, depending on the physical properties of the particles subjected to the separation process. The separator functions on the basis of the jump effect of the strongly conducting particles which assume different trajectories in the active zone of the field, namely, upper part of the drum. The experimental results and comments regarding the values obtained for grade and recovery for wastes consisting in Cu–Pb and Cu–Al mixtures are given.     

Separation of small metallic nonferrous particles in low concentration from mineral wastes using dielectrophoresis

This paper presents a theoretical study and a method regarding the separation of small nonferrous particles (Au, Ag) in low concentration from mineral wastes, using the dielectrophoresis phenomenon. The main theoretical considerations referring to the dielectrophoresis and the appearance and action of the electric gradient forces, typical for nonuniform fields, are presented. The gradient and superficial electric forces, in competition with gravitational forces, act on the dielectric particles from the surface of the material subjected to the separation process. Under the combined actions of all these forces, the metallic particles are concentrated on the surface of the mixture, forming a superficial conductive layer. Finally, the experimental results and conclusions regarding the concentrations in Au and Ag of the particles collected from the formed layer are presented, based on chemical analysis.