Effect of high voltage and electrode configuration on the trajectories of metallic particles in roll-type electrostatic separators for granular mixtures

Electrostatic separation is a technique that uses electric field forces exerted on charged or polarized bodies for sorting the constituents of granular mixtures in various domains: minerals beneficiation, food processing, waste recycling, etc. In the case of the specific electrostatic separator that is the subject of this study, the electric field is generated between a rotating-roll electrode, connected to the ground, and a static electrode with inverted S profile connected to a high voltage (HV) supply. This paper is aimed at evaluating the effect of two factors: the high voltage applied between the two electrodes and the distance between them. A high-speed video camera was used to record the trajectories of mm-sized aluminum and copper particles. The visualization of these trajectories provided a better understanding of the dynamics of particles movement in the electric field of the separator. It enabled to adjust the applied high voltage and the inter-electrode distance to avoid the impacts between the fine aluminum particles and the static electrode, while driving the two types of metallic particles into different collecting compartments. The conclusions of the study will be implemented on a pilot-plant roll-type electrostatic separator integrated to the production line of an industrial recycler. • Context: electrostatic separation of metal mixtures originating from WEEE. • Aim: evaluate the effect of two factors that influence the separation process. • Use of a high-speed video camera to record the separation trajectories. • Experiments on mm-sized aluminum and copper particles. • Avoid particle-electrode impacts by adjusting the applied voltage and the air-gap.