Triboelectrostatic separation is one of the advanced techniques for separation of plastic materials. This technique is based on the triboelectric effect. It is known that when electrically non-conducting particles of two different levels come into contact with electric charge, one of them becomes more positive (or negative) with respect to the other one. And their trajectories in electric field (affected by the charge they carry) may be quite different.
The separator consists of two electrodes, one of them being grounded. The voltage of the other electrode is on the order of tens kV. The electrodes may be covered by insulating material that prevents the particles from recharging in case of the direct impact with them. At the bottom of the device there are several recycle bins used for accumulating of particular levels of plastics.
- Mach, F., Kůs, P., Karban, P., Doležel, I.: Higher-Order Modeling of Electrostatic Separator of Plastic Particles, Przeglad Elektrotechniczny, 2012, Volume 88, Issue 12B, pp 74-76, pdf