Community Research and Development Information Service - CORDIS

An automatic system for separating plastics

An automatic system using fluorescent tracer technology has been developed to enable articles made from different plastics to be identified and sorted. The performance of the system has been exemplified using plastics packaging. The system comprises three components:
the tracer system (the tracers, compounds which emit characteristic fluorescent signatures when illuminated by ultraviolet light, are incorporated into the plastics either during polymer manufacture or by means of masterbatches which are added during conversion);
the sensor system (the sensor identifies the characteristic signature of the tracer and hence the host plastic, and provides a signal to activate a sortation machine);
sortation machine (when a signal is received from the sensor, an air jet is activated to eject the identified article into the appropriate storage bin).

The main benefits of this system are that it is fully automatic, fast, accurate and capable of identifying a large variety of different plastics. A variable voting system ensures that the optimal balance between sorting efficiency and purity of sorted fractions is maintained, even under conditions where the articles are contaminated. Unique features are that the system can discriminate between grades of the same polymer and, if required, can reject materials (such as plastics containing certain additives) that must be kept out of the sorted streams. The system is capable of identifying articles or shredded fragments as small as about 10 mm in dimensions, and with minimal separation between adjacent fragments. Thus, there is potential for the system to be developed for sorting shredder wastes. This has significant implications for industry sectors other than packaging, for instance the automobile and electrical/electronics industries. The system has also been tested and found to work satisfactorily with coloured plastics, although more research and development is needed in this area.

Reported by

Pira International
Randalls Road
KT22 7RU Leatherhead
United Kingdom
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