Aluminium from cars to cans: recycling for the future

Professor Geoff Scamans, Innoval Technology & Brunel University, at a seminar given to the Warwick Manufacturing Group (Warwick University).

Abstract: In the past ten years there has been considerable penetration of wrought aluminium alloys into automotive closure panels and structures particularly for luxury vehicles and sports utility vehicles. The exponential increase in demand for aluminium automotive sheet has resulted in major investments in heat treatment and finishing capacity across the globe. The change to electric propulsion is now producing a similar surge in demand for aluminium extrusions.

For automotive applications the key to making aluminium both embedded carbon and cost competitive with steel for more and more affordable classes of automotive vehicles lies in recycling of both prompt scrap (process and press shop) and, in the longer term, end of life vehicle scrap. For the first time scrap separation technology is available that can compete effectively with hand sorting in the developing world and has the potential to sort the aluminium fraction from shredded vehicle scrap both into wrought and cast alloys and then into individual alloy groups. Extracting cans from the non-ferrous concentrate from mechanical-biological-treatment domestic waste plants is relatively simple and can prevent this fraction ending up in landfill. The challenge is to use more and more end of life scrap in alloy formulation whilst at the same time extending the property range in terms of both strength and formability. For example simple thermomechanical treatments of AA6xxx alloy sheet, extrusions and forgings can significantly increase strength for strength dominated automotive applications as an alternative to either the use of AA7xxx alloys or high strength steel grades.