New charaterisation method of wastes of electric and electronic equipment
Résumé
The amount of waste electrical and electronic equipment (WEEE) will continue to increase in the coming decades with an expected rate of at least 4%/y, about three times higher than the growth of the average municipal waste because the market of the electrical and electronic equipment (EEE) is growing very fast.in the world. Innovative separation and beneficiation techniques of various materials encountered in WEEE waste is a major improvement for WEEE recycling. In this context, mechanical separation-oriented characterization of these wastes was conducted in an attempt to evaluate the flexibility of mechanical separation processes. A new methodology of characterisation was developed in BRGM. It is consisted on the sampling step followed by particle size distribution. Each size fraction is analysed manually to determine the colour, shape and liberation degrees of various products (plastics, metals ferrous and non-ferrous), which are essential for mechanical separation, were analysed by means of a grain counting approach. To identify the types of plastics, a mobile Phazir plastic detector based on IR spectroscopy was used, and the combination of magnetic and eddy current separations was performed to quantify ferrous and non-ferrous particles. The bromine was analysed by the instrument operates on the principle of x-ray fluorescence (Niton). Two different samples from different recycling industries were characterised in this work. The first sample is heterogeneous material containing different types of plastics, metals (ferrous and non-ferrous), printed circuit board (PCB), rubber, wood, etc. The second sample contains mostly plastics with high content of ABS. It is found that all aluminium particles are free (100%) in all investigated size fractions. Between 92 and 95% of plastics are present as free particles; however 67% in average of ferromagnetic particles are liberated. It can be observed that only 42% of ferromagnetic particles are free in the size fraction higher than 20 mm. Particle shapes were also quantified manually particle by particle. The results obtained show that the shapes of the particles, as a result of shredding, turn out to be heterogeneous, thereby complicating mechanical separation processes. In addition, the separability of various materials was ascertained by a sink-float analysis and eddy current separation. The second sample was separated by automatic sorting in four different products: ABS, PC/ABS, PC and rest product. The fractions were characterised by using the methodology described in this paper. The results show that the liberation degree of the plastic products (ABS, PC/ABS and PC) are close to 100%. Sink-float separation and Phazir plastic identification equipment confirms the high plastic quality. The products obtained from the automatic sorting of plastics containing brominated flame retardant were analysed by Niton which is confirmed the efficiency of the separation