Experimental Modeling of a New Triboelectrostatic Separation Process for Mixed Granular Polymers

Recycling of plastics from industrial wastes requires appropriate sorting technologies, such as the free-fall electrostatic separation of tribocharged granular materials. This paper introduces a novel electrostatic separation process characterized by the fact that the granules to be separated are charged in a fluidized bed affected by an electric field generated by two rotating roll electrodes. The experimental design methodology was employed for the modeling and optimization of the separation of a mixture composed of acrylonitrile butadiene styrene (ABS) and high-impact polystyrene (HIPS), originating from shredded obsolete computer cases. After processing the experimental data using the MODDE 5.0 software, the masses of ABS, HIPS, and middling collected after separation were expressed as quadratic functions of three of the control variables of the process: 1) duration; 2) speed of the fluidization air; and 3) high voltage applied to the electrode system. The obtained results demonstrate the effectiveness of this method for the separation of plastics from granular wastes.