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Post-shredder technology: Light at the end of the tunnel
| | Scholz AG conducted a large-scale test using its post-shredder technology on behalf of BMW. The centrepiece of the test, conducted at the Leipzig-Espenhain plant, was the post-shredder technology developed by Scholz AG. The object of the test was to ascertain whether and how it is possible to recycle all of the material from cars of the current generation.
By Walter Henkes
Rome wasn’t built in a day, as they say. And that old saying is still proving to be largely true, even in an age of ever faster technological change. This was also the case when Scholz AG carried out a large-scale test. On behalf of the Munich-based carmaker BMW, one of Germany’s foremost metal scrap recycling companies conducted a large-scale test together with French company Galloo Plastics S.A. using 501 of the premium manufacturer’s vehicles.
The centrepiece of the test, conducted at the Leipzig-Espenhain plant, was the post-shredder technology developed by Scholz AG. The object of the test was to ascertain whether and how it is possible to recycle all of the material from cars of the current generation. For this reason BMW used pre-series vehicles for the test. They had already been largely dismantled and relieved of any pollutants in the BMW works buildings so that nothing but pressed bodies were finally delivered to the Scholz plant in Espenhain.
Photo: Scholz AG
End-of-life Vehicles
Target: high recycling quotas
BMW selected Scholz AG for this large-scale test in order to achieve the highest possible recycling quota. Scholz has been continually enhancing its post-shredder technology over the last few years. In the meantime the technicians in Espenhain have succeeded in sorting the existing plastics from both the heavy (SSF) and light (SLF) fractions for further treatment.
The Scholz technicians have also repeatedly managed to increase their metal recovery rates. It is meanwhile possible to sort and recycle practically all of the metal parts in a car. The test was conducted in a total of four procedural stages:
1. Pre-treatment of the 501 pre-series vehicles from the year 2007 and the dismantling of selected components by BMW.
2. Recovery of the non-alloy steel content of the vehicles with the aid of shredding equipment (in this case a Kondirator from the company Metso Lindemann).
3. Treatment of the metal-bearing heavy and light fractions by means of post-shredder technology with the aim of recovering the remaining metals (steel alloys, NE metals) so that finally only the enriched plastic-rubber fraction and secondary fuel fraction remained.
4. Recovery of the recyclable plastics from the plastic-rubber product.
A technical expert from the company TÜV NORD AG as well as representatives from the Bergakademie Freiberg technical university monitored the large-scale test throughout the entire procedure. They also attested to the fact that the vehicles pre-treated by BMW were complete. The pyrotechnical components were neutralised as part of the pre-treatment. According to a joint press statement released by the companies taking part, all fluids and toxic substances were previously removed from the vehicles.
The starting weight of all vehicles (BMW and MINI models) totalled 761.76 tons and the empty weight of all vehicles in accordance with the end-of-life vehicles directive was certified as being 718.77 tons. In the process of dismantling, components intended for reuse such as body parts, front lights, rear lights and bumpers were removed. A total weight of 646.36 tons remained after dismantling. This amount was then subjected to the shredding process.
Heavy and light shredder fractions further treated
The pressed car bodies were then fed into the Kondirator for shredding. A total of 382.62 tons of directly recyclable steel scrap was recovered in the process. This left 145.94 tons of waste attributable to the heavy shredder fraction and another 110 tons of waste belonging to the light shredder fraction. The heavy shredder fraction mainly consists of non-magnetic metals, metal-bearing composites and plastics composites.
The light shredder fraction includes textiles, fibrous material, paints, polyurethane foams, plastics, rubber and glass. From the remaining 5.08 tons another 3.96 tons of copper-bearing composites were extracted by hand. The remaining 1.42 tons mainly comprised rubber, textiles and non-metallic composite materials. Apart from the steel scrap, all other fractions were further subjected to dry-mechanical treatment at the company Sächsische Recyclingwerke GmbH, located in Leipzig-Espenhain, a wholly owned subsidiary of Scholz Recycling AG & Co. KG. According to the press statement, although the procedure has been in operation since 2005, it is apparently still the only one in Europe that generates various metal and plastics fractions from the heavy and light shredder fractions fully automatically.
Chart: Scholz AG
In a process of classification, magnetic separation and multi-level inspection it is possible to recover the following products in pieces of up to 300 mm in size from the light shredder fraction:
- directly recyclable metals,
- metal-bearing composites (cables and circuit boards for further treatment),
- substitute fuels (non-metal composites of varying particle sizes),
- plastics and products consisting mainly of plastic for further treatment and mineral products with particle sizes smaller than 2 mm.
Chart: Scholz AG
The following products were recovered from the heavy shredder fraction by means of magnetic separation, classification by sieving and eddy current separation: metals (directly recyclable Fe, Al and Cu metals, steel alloys, Al-Fe composites), metal-bearing composites (Cu-Fe products, cables, circuit boards, composites suitable for further treatment), substitute fuels, products consisting mainly of plastic (various particle sizes) as well as dust and fibrous material (< 20 mm) and mineral particles (< 2 mm). At the end of the treatment 67.46 tons of rubber and plastics were recovered, although they partly included metal deposits.
Due to the fact that the landfilling of the high calorific value fraction will no longer be permitted when the landfill simplification regulations come into force next year, the further treatment of this particular plastics fraction was at the centre of interest during the large-scale test in Espenhain. Firstly, as much adhering metal as possible was to be separated from this heterogeneous plastics fraction and secondly the plastics were to be sorted into their various fractions. In this case Scholz decided on cooperation with the French company Galloo Plastics S.A. In France the separation of the various materials was carried out by means of a float-sink installation at a density of 1.50 g/cm3 followed by a subsequent eddy current separation and an additional float-sink separation, this time at a density of 3.2 g/cm3.
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