New Propeller-Type Tribocharging Device With Application to the Electrostatic Separation of Granular Insulating Materials

The aim of this paper is the development and functional optimization of a new propeller-type aerodynamic tribocharging device with application in the field of electrostatic separation. The originality of the system consists of its modular structure: one or several propellers can be stacked in the same device to provide appropriate tribocharging conditions to a wide variety of granular mixtures containing two or more of insulating materials. The study is conducted with samples of the following various insulating materials: polycarbonate, polyamide, acrylonitrile butadiene styrene, polyvinyl chloride, and high-impact polystyrene, grain sizes up to 4 mm in diameter, for several values of the propeller rotation speed, and of the mass of the particles in the tribocharging device, the wall of which are made of acetate, Polymethyl methacrylate (PMMA), or aluminum. The efficiency of the device is tested by processing the charged granular mixture in a metal-belt conveyor-type electrostatic separator. The aluminum-wall device enables better charging that PMMA and acetate. The mass introduced in the device has no significant effect on the outcome of the process, but the speed of the propellers does. Successful separation of a mixture of three insulating materials is reported.