Addition of X-ray fluorescent tracers into polymers, new technology for automatic sorting of plastics: Proposal for selecting some relevant tracers

A description of a new technology for automatic sorting of plastics, based on X-ray fluorescence detection of tracers, added in such materials is presented. This study describes the criteria for the selection of tracers, and concluded that the most adapted for XRF are some rare earth oxides. The plastics chosen for tracing and identification are the ones contained in ELV and WEEE from which discrimination is difficult for the existing sorting techniques due to their black colour.

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► The addition of X-ray fluorescent tracer to polymer materials provides positive and specific versatility, high purity of sorted fractions, efficient and effective sorting and identification of dark plastics.
► This study concluded that the tracers the most adapted for XRF detection are Y2O3, CeO2, Nd2O3, Gd2O3 and Dy2O3.
► The tracer concentration range suggested is [100–1000 ppm].