Tribocharging of Mixed Granular Plastics in a Fluidized-Bed Device

The output of any electrostatic separation process is strongly dependent on the effectiveness of particle charging. The aim of the present paper is to evaluate the effects of several factors that might influence the efficiency of a fluidized bed tribocharger, in the presence of an electric field orthogonally oriented to the direction of the fluidization air. The experiments were carried out on several synthetic mixtures of binary granular mixtures. The velocity of the fluidization air, the duration of the tribocharging process, and the composition of the mixture were the three process variables investigated. Whenever possible, the effects of these variables on the output of the process (i.e., the mass and the charge of the granules collected at the electrodes), were evaluated using the experimental design methodology. The results of full- and composite-factorial experimental designs were analyzed with a commercial software (MODDE 5.0, Umetrics). The effectiveness of the charging process was found to depend significantly on each of these factors. The propitious aerodynamic design of the device is a prerequisite for the successful industry application of the technique.