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Tribo-electrostatic separation of mm-size granular insulating materials is a process widely used in the plastics recycling industry. However, the separation of micronized plastics is still inefficient because of their tendency to aggregate. The paper is aimed at validating the feasibility of a new tribo-aero-electrostatic separation process for micronized mixed plastics originating from waste electric and electronic equipment. The separation process is based on a fluidized bed tribocharging system equipped with rotating roll electrode connected to a dc high-voltage supply. The micronized insulating materials to be separated (white and grey polyvinyl chloride particles of average size 20 µm) were tribocharged using the fluidization air provided by a variable-speed blower. The charged particles were pinned to the rotating electrode of opposite polarity. This process enabled the sorting of one product while the other materials were left in the fluidized bed. The new electrode configuration has the merit to significantly reduce the particle aggregation problem that affects the operation of other fluidized-bed-type tribocharging devices. The separation outcome, in terms of recovery and purity, depended on several factors, and was found to be optimal for a voltage of 35 kV and a rotation speed of roll electrode of 60 r/min. This new process was also tested for ternary mixtures of granular plastics and the obtained results demonstrate its effectiveness for recovering a targeted product, according to the voltage polarity, leaving the other products in the fluidized bed. [ABSTRACT FROM AUTHOR]

Commercial electrostatic separators have already been employed for the selective sorting of binary mixtures of granular materials. The aim of this paper is to validate the three-stage design of an electrostatic separator for recycling of plastics from granular waste electrical and electronic equipment WEEE. This separator, which combines two different methods of tribocharging, is specially built for processing ternary mixtures of granular materials. The experiment was performed on a mixture of polyvinyl chloride (PVC), high-impact polystyrene (HIPS), and acrylonitrile butadiene styrene. The purity of the obtained products was analyzed by using a program of image processing written in MATLAB. High purities (more than 81% for the PVC, 75% for the HIPS, and 97% for PA) were obtained at a recovery rate higher than 80%. [ABSTRACT FROM PUBLISHER]

Triboelectrostatic separation of millimeter-size granular plastic mixtures is widely used in recycling industry. However, electrostatic separation of micronized plastics is still inefficient since the adhesion and aerodynamic forces surpass the electric force. The aim of this paper is to optimize a new separation process for mixed fine granular plastics based on a fluidized bed tribocharging system. A pair of opposite high-voltage parallel plate electrodes are immersed in that bed and undergo a vertical alternating movement. The fine polyvinyl chloride particles of average size 0.1-mm particles to be separated are tribocharged using a fluidization air provided by a variable-speed blower. The charged particles are pinned to the electrodes of opposite polarities. The separation depends on several factors: the electric field, the speed of the electrode movement, the mass of the granular product, and the fluidization rate. The latter was the most significant factor, and the interval between the electrodes should not be less than 2 cm to avoid corona discharge. [ABSTRACT FROM PUBLISHER]