New aero-dynamic tribo-charging device with application to the electrostatic separation of granular mixtures of insulating materials

The aim of this paper is the development and functional optimization of a new propeller-type aero-dynamic tribo-charging device with application in the field of electrostatic separation. The originality of the system consists in 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 various of the following insulating materials: PC, PA, ABS, PVC and HIPS, grain sizes (up to 4 mm in diameter) for several values of the propeller rotation speed, and of the mass of the particles the particles in the tribocharging device, the wall of which are made of acetate, PMMA or aluminum. The efficiency of the device is tested by introducing the charged granular mixture into a 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.