Partnering to improve aluminum’s circularity

In November, Paris-based aluminum product producer Constellium SE announced it has partnered with a German automaker and OSR GmbH & Co. KG, a German recycling company, to sort mixed aluminum production scrap using laser-induced breakdown spectroscopy (LIBS) technology. Constellium says the partnership allows it to manufacture high-quality aluminum products with high scrap content without compromising material integrity, illustrating the viability of LIBS sorting and its potential to transform aluminum recycling globally.

Traditionally, mixed 5000 and 6000 series aluminum stamping scrap is downcycled. However, Constellium says OSR’s use of LIBS sorting technology has enabled this material to be sorted “rapidly” by alloy family at more than 95 percent purity so it can be put to its best use.

Fanny Mas, a metallurgist engineer at Constellium, says the company wanted to decrease the carbon footprint of its automotive products by incorporating the European automaker’s production scrap. “But one of the issues is that the alloy scrap is mixed at the stamping line, and there was no easy possibility to sort it directly at the production sites. And OSR had just acquired in August 2022 the LIBs machine. That's why it was decided that we were going to try, in a collaborative way, to sort this production scrap and see if we can remelt them back in order to make new products for the automotive industry.”

She says the collaboration began in September 2022, with deliveries of scrap beginning in April 2023.

The automaker sends its production scrap to OSR, which sorts the material before selling it to Constellium to be melted at its Neuf-Brisach plant in France.

Constellium’s Research and Technology team worked closely with OSR to set up the right operating conditions to meet the purity requirements that the aluminum producer expects for its products, which Mas says are “quite demanding in terms of application.”

Of the aluminum coils Constellium delivers to the automaker, she says approximately 30 percent to 40 percent will end up as stamping scrap, which illustrates why enabling the circularity of this material through better sorting is important.

Prior to LIBS sorting, the scrap is shredded and passed under a conventional magnet to remove any ferrous contamination. . The LIBs technology then sorts the material by alloy family, and Constellium uses the 5000 series and the 6000 series scrap streams to produce new products.

If the company were to use the mixed scrap stream, Mas says the resulting alloy would be too high in magnesium to be used as 6000 and too high in silicon to be used in a 5000. “It’s would really not be efficient, and it would require a lot of primary metal to dilute it to get to the right composition.”

Since 2023, Constellium has melted several tons of the LIBS-sorted scrap in its furnace at Neuf-Brisach, Mas says as of late November.

“For these dedicated customers, having this closed-loop recycling allows us to significantly reduce the carbon footprint of the products,” she says. In most cases, the preconsumer scrap Constellium receives from its customers is not mixed and can be used directly in its furnaces without first needing to be sorted.

For the mixed scrap, Mas says LIBs could present a short-term solution, while a more medium-term option could be investing to prevent the alloys from mixing during the manufacturing process. “And then in the long term, we are beginning to see a switch toward the unialloy design—all 6000—and in that case, even if you have different alloys of 6000, it would be OK for them to be mixed together.”

However, given the success of its first three-party arrangement with OSR and the German automaker, Mas says Constellium is interested in developing more such relationships. “It’s really something we want to extend,” she says, “and it’s working well with OSR and the German OEM.”

Constellium recently increased capacity at its Neuf-Brisach plant. “I would say all types of scrap are welcome in our operation,” Mas says of that site. “And this clean production scrap is really efficient. And that's why we think, even if it's mixed at the OEM, there is an interest in sorting it in order to be able to incorporate it. It should give us access to scrap that would be otherwise downcycled. Most of the time when the scrap is mixed, even if it's a good quality scrap, it's going to end up in secondary alloy casting because of the composition being far away from being compatible with the existing automotive sheet grades. LIBs sorting opens the way to upcycle some scrap that was recycled but to other less-demanding applications.”

By 2030, Constellium’s goal is for recovered aluminum to comprise 50 percent of its metal inputs, though it does not distinguish between preconsumer and postconsumer sources.

Regarding postconsumer scrap, Mas says the company has been doing a great deal of R&D work, which includes working with LIBS but also evaluating other technologies. “We have been working with, different scrap dealers and different technology providers,” she says. “The results so far are quite good. On the technical side, I would say, for example, we were able to achieve the same type of purity that we achieve on the preconsumer scrap on the postconsumer scrap. The main difficulty with the postconsumer scrap is related to the part of material that you will be able to valorize when you do the sorting.”

While Constellium can use 100 percent of the mixed production scrap, twitch, which the Recycled Materials Association defines as the post auto shredder mixed aluminum fraction derived from wet or dry media separation that contains no more than 1 percent maximum free zinc, 1 percent maximum free magnesium and 1 percent maximum of analytical iron, is largely casting scrap, which the company has no use for as an extrusion and sheet producer. While it has seen success recovering wrought grades from twitch, they are more limited, which affects the cost-effectiveness of the process. “We are quite satisfied and impressed by what the technology is able to do on the technical side but are waiting to see how it's going to evolve for the postconsumer side,” Mas says. “And we expect that in the coming years as the aluminum that has been introduced into vehicles has increased year after year, you will have more and more wrought aluminum in the twitch,” making the technology more cost-effective, she adds.