Verfahren zum Sortieren von Kunststoffen aus einem Partikelgemisch unterschiedlicher Kunststoffe

摘要

Sepn. of a mixt. of different types of plastic particles into pure types involves flotation by treating the particles to modify their wetting property according to type, so that the various types can be floated individually from the mixt. The novelty is that the wetting property is modified by dry physical plasma treatment before flotation and outside the flotation unit, followed by storage. Pref. the mixt. is reduced to a particle dia. of less than 20 mm., pref. 2-12 mm., then subjected to plasma treatment in batches of loose material or continuously, pref. in a single layer. Plasma treatment is carried out for 1-120 s. in the presence of a microwave-stimulated process gas, pref. O2 at a pressure of less than 200 Pa. Suitable treatment times and pressures are 5-10 s. and 10 Pa in small plant and/or thin layers; and 60-120 s and 30 Pa in larger plant and/or thicker layers. Plasma treatment may also be carried out continuously in an open atmos. in the presence of air, in which case atmos. O2 and/or N2 is stimulated to a plasma in the treatment zone, esp. by a direct barrier discharge.