Endurance Test of a Rotating-Cylinder-Type Tribocharger

The electric charging of granular plastics in view of their electrostatic separation is one of the major industrial applications of the triboelectric phenomenon. The granules get charged by collisions and frictions with each-others and with the walls of the tribocharging device. In electrostatic separation applications, the granules of a mixture must be sufficiently charged to be attracted by electrodes of opposite polarity for their separation by type of material. The objective of the present paper is to study the endurance of a novel rotating-cylinder-type triboelectric charger for two types of granular materials (sizes between 2 mm and 5 mm), originating from waste electric and electronic equipment: Acrylonitrile Butadiene Styrene (ABS) and Polystyrene (PS). The performance of the triboelectric charger was evaluated by measuring the charge per mass ratio of the granules collected at the outlet of the device. The outcome of the process depended on the rotation speed of the cylinder, as well as on the mass flow rate of product. The charge per mass recorded at the start of the process (typically 5 nC/g pour ABS and 2 nC/g pour PS) decreased in time, due to the saturation of the tribocharging cylinder.