Whether it's in skyscrapers or innovative electronics, metals are the foundation of modern industry. Aluminium is noted for its relatively low weight and its significant energy inputs in production. Recycling aluminium saves considerable energy when compared with primary aluminium, but the automotive industry is facing a new challenge. With the transition towards electric vehicles accelerating, existing practices for recycling end-of-life car scrap may no longer be sufficient.
Historically, automobile recycling has been a reliable source of aluminium, with the major portion of it going back into engine blocks in newer combustion vehicles. However, with the end of engines, it raises the question of what will happen with all of the scrap? If there aren't avenues for car manufacturers to market scrap aluminium, we could see millions of tonnes built up for waste, which adds more waste and causes the industries to consider virgin aluminium, taking us back to years of reductions from emissions.
Obstacles in recycling aluminium
The urgency of the challenge is increasing. Electric vehicles require fewer conventional engine components, and are the primary source of recycled aluminium for automotive applications. Stefan Pogatscher from the University of Leoben noted that without engine blocks, there is not one settled solution for this scrap, when asked where the recycled aluminium from ICE vehicles will go.
This is a serious challenge since the aluminium cars turned into waste will be huge and their potential applications even greater, which in Europe alone is over 7 to 9 million tonnes of automotive aluminium waste created each year.
Without an available solution, this material may be sent to landfill or down-cycled when scrap is generated, while automakers are still creating carbon-heavy aluminium for new electric vehicles.
New method to the rescue
According to Pogatscher and his team, instead of separating aluminium along multiple recycling streams, they are melting each of the scrap alloys together in one process.
Modern vehicles can have 40 different aluminium alloys, while traditional recycling would separate the alloys into streams and sort the scrap. This new method allows all the aluminium alloys to be melted together, allowing for impurities, and is done in bulk in one step.
For the first step, melt the scrap alloys into a slab, described as brittle "like a ceramic". The slabs are useless at first, but if Pogatscher's team heats the slab to 500 degrees Celsius for 24 hours, they can restructure the internal structure, changing the property of that material from fragile to a ductile and strong material that is obviously reusable.
Also read: Global aluminium recycling market faces scrap squeeze amid surging demand
Recycled aluminium with improved strength
Pogatscher pointed out that in some instances, the recycled material has better mechanical properties than primary-produced wrought alloys. This indicates that the recycled aluminium can provide the same strength, and sometimes exceed the strength, of newly mined material. This provides opportunities for using this material in structural automotive applications, like chassis and frames.
The best part is that it will fit with the existing industrial equipment, which could ease the scale-up process compared to other advanced recycling attempts. However, Pogatscher admits that it will take some time to build a trusting relationship with a conservative industry for them to accept new material.
Scepticism about aluminium recycling
Geoffrey Scamans of Brunel University London described the work as "very interesting" but said it must undergo rigorous testing. Automotive body components are tested to stringent performance criteria, and until any recycled alloys meet every criterion, they will not be produced.
Scamans also expressed concern about consistency, since vehicles are scrapped randomly and every batch of materials could be substantially different. This unpredictability could affect the feasibility of producing consistent, reliable, high-grade alloys at scale.
Method to control the challenge
Mark Schlesinger of the University of Missouri of Science and Technology presented another hurdle. While melting scraps of alloys together may appear efficient, the chemical composition is essential. Schlesinger described that if you put some scraps in the furnace and then throw in some more scraps at a later time, you will not get a finished product that is of acceptable quality.
In other words, the manufacturers are going to have to identify the chemical content of the alloy and monitor it, potentially raising total costs. This adds a layer of complexity to a process intended to make recycling more feasible.
Also read: Recycling gains ground as aluminium industry rethinks dross disposal
Therefore, it might not be enough to monitor only the alloy and label the metal, whether the chemical traceability is needed or a system that utilises state-of-the-art sorting equipment? Without any such monitoring, scrap alloys could forfeit compliance with industry standards and diminish their usage in products.
Aiding in waste and emission reduction
Irrespective of the drawbacks, the potential benefits are substantial and cannot be ignored. The production of primary aluminium continues to be one of the most energy-intensive processes in the industrial sector and it is a significant contributor to carbon emissions globally.
Moulding millions of tonnes of automotive scrap into high-quality alloys could reduce waste and emissions. In Europe alone, preventing 7 to 9 million tonnes of scrap from being thrown away yearly would improve the environmental impact of the automotive sector. If the process can be scaled, it could open the door for similar projects in other aluminium-based industries.
Prospects of this method
Pogatscher has showcased the possibilities of reimagining the aluminium recycling market. Their strategy could give the automotive sector an essential remedy for transforming waste into a usable resource for the next generation of vehicles. However, challenges still exist to ensure consistency of materials and to convince manufacturers to use a new alloy.
In the upcoming years, the result highlighting whether this innovation can make a meaningful impact on the recycling of aluminium or will be considered an experimental breakthrough will be understood. Regardless, what is clear is that the consequences of the experiment, which is keeping scrap aluminium in circulation, could help to reduce emissions and ultimately allow the industry to be cleaner and more sustainable.
Also read: Here’s how to turn 9Mt of car waste into aluminium alloy for next-gen EVs
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