Modeling and optimization of a propeller-type tribocharger for granular materials

Electrostatic separation has already proved to be an effective means for the recycling of granular plastics from industrial wastes. The aim of the present work was to optimize the operation of a novel device that could ensure effective triboelectric charging of such materials prior to their selective sorting in a high-intensity electric field. The experiments were performed on two sorts of mm-size granular materials Acrylonitrile Butadiene Styrene and High Impact Polystyrene, originating from the processing of waste electric and electronic equipment. The samples were introduced in a Polyvinyl Chloride cylinder, where a co-axial propeller entrained the plastic granules into a helical motion that favored their triboelectric charging by combining the mechanical and aerodynamical effects. The experimental design methodology was employed for the modeling and optimization of the tribocharging process.

► Optimization of a new tribocharging device for granular materials.
► Composite factorial experimental designs performed on ABS and HIPS granular wastes.
► Charge evaluated by electric field measurements at the surface of a granular layer.
► Highly-efficient tribocharging by combined mechanical and aerodynamical effects.
► Possible application: tribo-electrostatic separation of plastics from granular wastes.