Electrostatic Separation of Tribocharged Granular Mixtures of Two or More Plastics Originating From WEEE

Electrostatic separation is able to process mixtures of plastics from waste electrical and electronic equipment. The efficiency of the electrostatic separation depends on the electric charge acquired by the particles in the appropriate tribocharging devices. The aim of this work is to validate the possibility of using a roll-type electrostatic separator to sort mixtures of particles that are difficult to process by other means. In this type of separator, the plastic particles are charged by triboelectric effect. Two types of charging devices have been used: fluidized bed and rotating multicylinder. Two series of experiments were performed with samples composed in equal proportions of: first, acrylonitrile butadiene styrene (ABS) and polystyrene (PS); second, polypropylene (PP) and polyethylene (PE). A third series of experiments were carried out with a mixture of three plastics: PP, PE, and ABS, and the last series of experiments were carried out with a mixture of four plastics of (PE/PP/ABS/PS), with an average particle diameter ranging between 3 and 6 mm. The efficiency of the electrostatic separation was evaluated by measuring the charge, purity, and recovery of the granules collected at the outlet of the electrostatic separation. The results confirm that the separation of ABS/PS and PP/PE mixtures is feasible and the best separation results were obtained using the fluidized bed tribocharger.