Optimized industrial sorting of WEEE plastics: development of fast and robust h-XRF technique for hazardous components

Waste electrical and electronic equipment (WEEE) are a source of both hazardous and valuable materials that must be segregated for treatment. Previous studies addressing the use of handheld X-Ray fluorescence (h-XRF) as a sorting tool for WEEE plastics through the identification of hazardous components include plastics from mixed WEEE streams, processed material (shredded or treated plastics) and low number of samples not allowing to consider their findings for application on an industrial scale. Thus, further research is needed to establish scalable robust methods for sorting this material. We describe a study carried out on whole flat panel display equipment (FPD) plastic casings using h-XRF for the detection of total bromine (Br) and antimony (Sb) as tracers for Brominated Flame Retardants (BFRs) and Sb₂O₃ additives. The aim being to characterize the targeted material and to define the optimal analysis conditions to meet large scale throughputs. A ring trial exercise comprising 100 samples was conducted to evaluate the validity of the measurements. Results indicate that: 1) the use of h-XRF under the conditions determined in this study offers a valid technique to screen total Br and Sb in whole FPD casings at industrial scale with low uncertainty, 2) Br and Sb are found to be homogeneously distributed within the casing, 3) an optimal h-XRF analysis time of 10 seconds is suitable from both accuracy and practical implementation for LOD<[Br]≤ 830 mg kg⁻¹ and LOD<[Sb]≤8400 mg kg⁻¹, and 4) the presence of dust deposited on the casings was excluded as a factor affecting h-XRF results. To our knowledge this is the first evaluation of optimal sorting conditions for whole display casings using h-XRF, within a manual dismantling process.