New characterisation method of electrical and electronic equipment wastes (WEEE)

Abstract

Innovative separation and beneficiation techniques of various materials encountered in electrical and electronic equipment wastes (WEEE) is a major improvement for its recycling. Mechanical separation-oriented characterisation of WEEE was conducted in an attempt to evaluate the amenability of mechanical separation processes. Properties such as liberation degree of fractions (plastics, metals ferrous and non-ferrous), which are essential for mechanical separation, are analysed by means of a grain counting approach. Two different samples from different recycling industries were characterised in this work. The first sample is a heterogeneous material containing different types of plastics, metals (ferrous and non-ferrous), printed circuit board (PCB), rubber and wood. The second sample contains a mixture of mainly plastics. It is found for the first sample 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 larger than 20mm. Particle shapes were also quantified manually particle by particle. The results show that the particle shapes 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 sensor sorting in four different products: ABS, PC-ABS, PS and rest product. The fractions were characterised by using the methodology described in this paper. The results show that the grade and liberation degree of the plastic products ABS, PC-ABS and PS are close to 100%. Sink-float separation and infrared plastic identification equipment confirms the high plastic quality. On the basis of these findings, a global separation flow sheet is proposed to improve the plastic separation of WEEE.

Characterization and mechanical separation of metals from computer Printed Circuit Boards (PCBs) based on mineral processing methods

“…To choose a suitable cut-off size for an adequate comminution, the valuable are liberated from non-valuable and it is necessary to determine the liberation degree (Menad et al, 2013). The liberation degree is a simple ratio of the number of free particles of the desired material to total number of the desired particles (locked particles plus free particles).…”

“…It is a desired upgrading method for it can yield full material recovery including plastics and prepare a richer and cleaner feed for pyro-and hydrometallurgical processes. E-waste contains a large amount of different engineering plastics that need further separation by advanced separation techniques in order to produce high added value plastics (Menad et al, 2013).…”

“…Kasper et al (2011) carried out a similar investigation but focused on scraps of printed wiring boards of mobile phones (Kasper et al, 2011). Menad et al (2013) proposed a global separation flowsheet to improve the plastic separation of WEEE based on Mechanical separation-oriented characterization (Menad et al, 2013). The recovery of metals through the use of a column air classifier was studied by Eswaraiah et al (2008) and the performance at different rates and air velocities for the constant quantity of the feed was investigated (Eswaraiah et al, 2008).…”

Use of natural clays as sorbent materials for rare earth ions: Materials characterization and set up of the operative parameters

“…valuable metals). In this perspective, wastewaters generated by hydrometallurgical processes of Waste Electric and Electronic Equipment (WEEE) treatment could be a potential target of this kind of processes, since they contain a large amount of valuable metals (Behnamfard et al, 2013;Menad et al, 2013;Mueller et al, 2015). The main available technologies for metal recovery are electrodeposition (Fogarasi et al, 2015), solvent extraction (Akcil et al, 2015) or precipitation (Behnamfard et al, 2013); they are able to purify and recover noble metals as copper, gold or silver, but they are still quite unsatisfying for what concerns Rare Earths (REs) (Binnemans et al, 2013).…”

Steam gasification of printed circuit board from e-waste: Effect of coexisting nickel to hydrogen production

“…In Europe, the amount of WEEE generated is 12 million tons per year, only 18% of which is treated [2]. About 100 million mobile phones and 17 million computers are estimated to be wasted annually around the world [3].…”