Innovative recycling methods for metals extracted from scrap cars can potentially eliminate millions of tons of waste annually while decreasing carbon emissions associated with the production of new aluminum.

Historically, a significant portion of scrap aluminum from cars has been repurposed into lower-grade cast alloys for engine blocks in traditional combustion engines. Yet, as the auto industry shifts towards electric vehicles, this low-grade metal no longer has utility.

Without effective strategies, there is a risk of generating millions of additional tons of carbon dioxide by accumulating “mountains” of unusable scrap and increasing the production of virgin aluminum for new vehicle manufacturing, warns Stephen Pogatcher from Leven University in Austria.

“As engine blocks become obsolete with electrification, we lack current paths for scrap utilization,” he cautions. “This constrains our recycling capabilities.”

Pogatscher and his team have developed a novel approach for recycling metals from scrap vehicles, which could convert approximately 7-9 million tons of waste annually into high-quality aluminum alloys suitable for various components of new cars.

The key lies in generating new products by harnessing a variety of alloy materials sourced from scrap vehicles, he elaborates.

Typically, when a car is discarded, its materials—plastic, fabric, steel, and aluminum—are processed separately. Moreover, as many as 40 different aluminum alloys are extracted from each vehicle across various recycling streams. Any non-separable components tend to blend into the engine block, associated with combustion engines.

The innovative recycling method pioneered by Pogatscher’s team involves melting all the scrap aluminum from the car simultaneously.

This results in a block of highly brittle material that resembles a metal ceramic, according to Pogatscher. Interestingly, the team found that reheating this block at approximately 500°C for 24 hours can restructure the metal, enhancing its strength and toughness. “Ultimately, it offers improved mechanical properties compared to conventional alloys,” he notes.

The team asserts that this new material rivals traditional automotive alloys, featuring “impressive” strength and versatility for fabricating various car components, including chassis and frames. Pogatscher emphasizes that it can be produced using standard industrial practices and has the potential for rapid scalability. While he recognizes the challenges in mainstream adoption of new alloys within the conservative manufacturing sector, discussions with industry partners regarding process development are already underway.

Jeffrey Scamans at Brunel University in London finds the concept “very intriguing,” but he stresses that further validation is essential, particularly to ensure the new alloy meets the stringent testing requirements for automotive applications.

He also cautions that achieving consistent high-quality alloys may be difficult since vehicles are discarded in a varied manner, not according to specific types. “It’s challenging to envision how to collect individual alloy compositions practically,” he remarks. “Scaling from laboratory experiments to full-scale metal production is notoriously complex.”

Mark Schlesinger at the Missouri University of Science and Technology states that commercial production must delineate and manage the composition of the new alloy. “Randomly mixing scrap in the furnace won’t yield acceptable results,” he says. “This necessitates precise scrap chemistry assessments, which subsequently raises handling costs.”