Experimental study of a new tribocharging device for the electrostatic separation of mixed granular insulating materials

Recycling of waste plastics is a complex process, which often includes an operation of electrostatic separation, the efficiency of which depends on the electric charge carried by the particles. The present work is aimed at evaluating the performances of a new multi-cylinder-type tribocharger for granular plastics (size: 3 mm to 5 mm). The design of the device ensures a quasi-permanent particle-wall friction that improves the tribocharging efficiency. The experiments were carried out using PVC as material for the tribocharging cylinders and involved nine different polymers. Charge per mass ratios higher than 10 nC/g were obtained for PC and ABS particles, i.e. a level of charge that is adequate for electrostatic separation.