Your browser is no longer supported

For the best possible experience using our website we recommend you upgrade to a newer version or another browser.

Your browser appears to have cookies disabled. For the best experience of MRW, please enable cookies in your browser

We'll assume we have your consent to use cookies, so you won't need to log in each time you visit our site.
Learn more

Why sorting through residue is worth it

Once a vehicle has had valuable parts removed, along with any pollutants such as the oil, fuel and battery, it is ready to be crushed, baled and shredded. But that is by no means the end of the process for recovery.

Thanks to a variety of processes – including magnetic, sink/float, air separation and induction/ X-ray – metals and plastics are also saved from landfill to be recy­cled or reused.

An issue has always been what to do with all that is left behind after all of the above have been carried out. Despite containing several types of potentially valuable materials, such as plastic (about 45%), textiles (29%) and foam (13%), as well as smaller quantities of rubber, ferrous met­als, aluminium, copper and paper, it has not been possible to separate and recover this automotive shredder residue (ASR) cost effec­tively, so instead it has all gone to landfill.

The challenge faced by those looking to process ASR is that it has already been through a com­prehensive series of sorting procedures to extract as much material as possible. What remains is largely the result of inefficiencies in those methods.

Few, if any, suppliers offer technology that can process asr sufficiently well to extract the variety of resources present.”

But there is value in going the extra mile to recover more resources, for sustainability pur­poses as well as economic ones.

Extra wet screening and sorting will be of most benefit to the larg­est ASR recyclers. The volumes they process and the high degree of automation in their plants mean that processing material below 20mm becomes worth­while. It can bring in added value rather than being a cost.

The early stages of ASR pro­cessing usually involve using a trommel or flip-flow screen to extract the main constituents at less than 15 or 20mm, including sand, glass and mineral (40%), plastics (25%), organics (20%) and metals (15%).

The remaining metals are often the next focus; some are removed using basic dry screening, mag­nets, eddy current separator (ECS) and perhaps density separation, wind sifting or air knife.

Finally, the remaining material is washed and screened to produce further sand and aggregates that meet legislation for secondary aggregates reuse. The materials that are recovered can be suitable for a range of applications, includ­ing embankments, fill materials, capping and sub-base for paving areas.

automotive shredder residue

automotive shredder residue

At this stage, plastics that may be suitable for further processing or incineration can also be recov­ered. Much of any remaining fer­rous and non-ferrous metals can also be recovered at this stage.

Few, if any, suppliers offer tech­nology that can process ASR suffi­ciently well to extract the variety of resources present. Instead, plants dealing with ASR tend to rely on a number of suppliers and form modular solutions.

To extract full value, an ASR plant may require a shredder, finger and flip-flow screens, wind sifting, air knife, wet sink/float system, magnet ECS steps, in-duction and X-ray separation technology, milling and density separation.

This is not something that can be done on a small scale. A sophis­ticated plant averages operating costs of around £500,000 per process tonne per hour, meaning that a 20-tonne tonne/hour plant may require a £9m+ investment.

If we are to truly achieve a cir­cular economy, which keeps resources in the loop, every aspect of material recovery needs to be implemented. CDEnviro is proud to be playing its part in this recov­ery challenge, making sure that sifting through scrap is worth­while and the remaining resources are saved from landfill.

We know the challenge is far from over. In future, ASR will no longer be the biggest problem in automotive recycling. With more and more cars being made as com­posites – so that they are lighter and consume less fuel – there will be new challenges for those look­ing to recycle them. We will be looking to play our part in those solutions too.

Sean Dobbs is senior product development engineer at waste management specialist CDEnviro

Have your say

You must sign in to make a comment

Please remember that the submission of any material is governed by our Terms and Conditions and by submitting material you confirm your agreement to these Terms and Conditions. Links may be included in your comments but HTML is not permitted.