Fluidized bed device for plastic granules triboelectrification

The study of the triboelectrification process is the key factor to the successful industrial application of electrostatic separation in the field of plastics recycling. Therefore, the aim of the present work is to evaluate an original device for the laboratory study of this process. The original design of the fluidized bed type triboelectrification device has the following distinctive features: (i) transparent walls to observe the fluidization process and the particles moving in the triboelectrification module; (ii) air distributors with different mesh apertures correlated with granule size; (iii) quick replacement of the triboelectrification Plexiglas chamber with other metallic ( aluminium, copper) or nonmetallic chambers ( polyvinyl chloride - PVC, polyethylene - PE, and polyethylene terephthalate - PET); (iv) possibility of independent operation, for granule charge measurement or integrated operation, for the electrostatic separation experiments using a free-fall electrostatic separator. The results of charge measurement experiments pointed out the different triboelectric behaviour of two types of granules ( polystyrene and low-density polyethylene) in contact with the walls of the device. The electrostatic separation experiments carried out on a binary mixture of mm-size polystyrene/polyethylene granules confirmed the effectiveness of the triboelectrification device.