Our study showed that a pre-treatment of dismantled rear lights ahead of the solvent extraction process is technically feasible. Pre-concentration of PMMA and ABS by gravity separation using a novel jigging process developed at the Delft University of technology proved successful, notwithstanding the small density difference between the components to be separated. Electrostatic separation as part of the treatment is suitable for the process as exemplified in several discontinuous tests at the Delft University of Technology as well as by independent continuous tests performed by Hamos GmbH in Prenzberg/Germany. The results are corroborated by the fact that in the Hamos tests, a different type of electrostatic separator was used. However, electrostatic separation in continuous operation during our pilot study failed to reproduce previously gained results in discontinuous operation, probably due to a machine failure caused during the transport of our machine to Eurotec. There are indications that the solvent extraction process is not essential to produce a high-grade ABS fraction from dismantled rear lights. In general, a purity of about more than 98 wt-% is required for recycled ABS with respect to organic contaminants. Tests at Hamos GmbH indicate that electrostatic separation can possibly replace solvent extraction in this application. Especially a combination of jigging, producing an ABS pre-concentrate with a purity of about more than 90 wt-%, and electrostatic separation seems suitable. However, more data are needed to prove this concept. In particular, the talcum-reinforced PP content of the ABS fraction is critical, which has to be less than 1 wt-%, according to Eurotec. Our study exemplified that mechanical separation techniques are suitable to treat multi-component plastic mixtures for material recovery. Our next study will focuse on even more complex mixtures, e.g. wheel covers and the rigid plastic fraction of shredder residue. It appears that a similar strategy as for dismantled rear lights can be applied for such mixtures. A pre-concentration step by gravity techniques, e.g. jigging, is used to separate the mixture into a number of two - or three - component mixtures that are turned into final concentrates by electrostatic separation. Note that gravity techniques and electrostatic separation are synergistic for such applications. This is because gravity techniques are not suited to separate plastics with a density overlap between the components, e.g. ABS and talcum-reinforced PP, but such mixtures can be handled using the electrostatic technique. On the other hand, electrostatic separation is mainly suited to separate two-component mixtures. An important advantage of jigging for the gravity step is that it produces three pre-concentrates in a single stage: a float fraction (less than 1.0 g/cm(exp3)), light sink fraction and a heavy sink fraction.
Mechanical recycling of dismantled car rear lights
Mechanisches Recycling von demontierten Autorücklichtern
2003
14 Seiten, 5 Bilder, 6 Tabellen, 6 Quellen
Aufsatz (Konferenz)
Englisch
Automobilbau , Kraftfahrzeug , Rückführung , Recycling-Technik , Wiederverwertung , Pilotanlage , ABS-Polymer , PMMA (Polymethylmethacrylat) , Polypropylen , Polycarbonat , Kunststoffrecycling , Beleuchtung , Vorbehandlung , Demontage , Gravitationskraft , Dichte , Trennen , elektrostatische Anziehung , Reinheitsgrad , Gemisch , Setzarbeit
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