Quality assessment of mixed plastic flakes from Waste Electrical and Electronic Equipment (WEEE) by spectroscopic techniques

The quality of mechanically recycled plastics from WEEE is seen as one of the main bottlenecks for their re-application in high-quality products to enable a circular economy for these materials. Most literature focuses on the quality at the end of the value chain while significant potential to improve the performance of the entire value chain is seen by the quality assessment of input material of recyclers. In this research a testing procedure for mixed plastic flakes by Fourier-Transform InfraRed (FTIR) spectroscopy, X-Ray Fluorescence (XRF) and manual composition analysis assisted by computer vision. Mixed plastics from TV housings, washing machines, fridges and fridge drawers were taken as case studies. It is shown that unwanted plastic types, glass, metals, wood, rubber and foam as well as additives such as talc, calcium carbonate or brominated flame retardants can be detected by the procedure. In addition, a Failure Mode and Effect Analysis (FMEA) is shown to be a powerful tool for a risk-based assessment of the most relevant quality influences, which allows to define strategies for quality control. The economic evaluation showed that automation is required to allow the systematic use of the testing procedure.