Experimental modelling of a new tribo-electrostatic separation process for micronized plastics

Tribo-electrostatic separation of mm-size granular plastics 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 PVC 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. This latter was the most significant factor and the interval between the electrodes should not be less than 2 cm to avoid corona discharge.