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Circular economy closes loop on scrap aluminium

05 February 2024

Recycling scrap aluminium for high-grade building materials can achieve energy savings of 90 percent.

Image: Andrea Starr | Pacific Northwest National Laboratory
Image: Andrea Starr | Pacific Northwest National Laboratory

The circular economy just closed the loop on scrap aluminium, thanks to a new patent-pending technology developed at the Department of Energy’s Pacific Northwest National Laboratory. 

That twisted aluminium mesh, those banged-up bicycle frames, and the used car parts now languishing in junk yards could gain new life as building structures such as door and window frames, facades, lighting, decorative features and a myriad of other uses – all while conserving nearly all the energy required to manufacture new aluminium products.

It’s no secret that strong, yet lightweight aluminium parts are being deployed more often as building materials. However, there’s a high energy and greenhouse gas emissions cost to mining and refining aluminium. According to the International Aluminum Institute, the production of one ton of primary aluminium emits an average of 17 tons of carbon dioxide into the atmosphere.

Now, rather than processing mined aluminium, rigorous laboratory testing has shown that PNNL’s Shear Assisted Processing and Extrusion Process (ShAPE) can transform 100 percent post-consumer scrap aluminium into usable extrusions that meet or exceed stringent ASTM standards for strength and flexibility for common building-grade alloys 6061 and 6063. 

The ShAPE technology unlocks the possibility of creating circularity in aluminium scrap markets, thus reducing dependency on imported primary aluminium and the massive amounts of energy associated with its production.

“With approximately 55 percent of the global aluminium extrusion market servicing the building and construction industry, the evolution of ShAPE to include aluminium recycling for building structures is an enormous opportunity for decarbonising the built environment,” said PNNL Chief Scientist Scott Whalen, who led this research. 

“We are finding that the unique microstructures within the metal are more tolerant to impurities than previously thought. This enables us to reach even deeper into the aluminium scrap market while maintaining material performance.”

The latest round of patented ShAPE technology prompted technology entrepreneur Eric Donsky to form a start-up manufacturing company to scale a ShAPE-based process into vertically integrated manufacturing facilities that upcycle scrap aluminium into a portfolio of low-carbon extruded parts initially targeting the building and construction industry.

Atomic13 has signed an exclusive agreement with PNNL to commercialise the technology in certain fields of use and aims to move rapidly to create a myriad of custom-extruded aluminium parts for the building and consumer product industries, relying entirely on post-consumer aluminium scrap. 

The energy savings is expected to assist builders aiming to meet or exceed Leadership in Energy and Environmental Design standards for energy-efficient buildings, among other benefits.

“The ShAPE technology is an amazing opportunity for US manufacturing and the build-out of our critical infrastructure,” said Atomic13 Founder Eric Donsky. 

“We believe there is tremendous environmental and commercial value to building circularity in the aluminium extrusion industry while helping the building and construction industry significantly reduce the embodied carbon of their products.

“ShAPE technology enables companies like Atomic13 to produce aluminium extrusions made from 100 percent post-consumer scrap with 90 percent lower carbon. At the same time, the low feedstock costs result in lower costs for consumers. 

“We look forward to continuing to work with PNNL engineers to advance this promising technology.”

Aluminium extrusions are already a mainstay of the building industry. What’s different about the ShAPE manufacturing process is that the scrap aluminium bricks or rod-shaped billets are deformed using heat generated by high shear forces to pulverise impurities in scrap aluminium into tiny particles and uniformly disperse them within the aluminium microstructure. This dispersion eliminates, for example, microscopic iron clumps that can generate microfractures in recycled aluminium products manufactured using conventional methods. 

ShAPE aluminium extrusion offers massive energy savings by eliminating the need to dilute impurities found in recycled aluminium with 25 percent to 40 percent newly mined aluminium before processing.

The PNNL team evaluated the mechanical properties of rods, tubes and irregular hollow, multichannel trapezoids under mechanical stress. The team tested 540 unique conditions products, made from post-consumer scrap briquettes, some with high iron content (0.2 to 0.34 percent iron). All performed at or above ASTM standards for yield strength and ultimate tensile strength.

Creating new demand in the scrap aluminium market
According to the International Aluminum Organization, producing one metric ton of molten aluminium requires 16.6mWh of electricity. Globally, the aluminium industry produced over 69,000 metric tons of primary, mined aluminium in 2022. Half of that came from China, which uses coal-fired power to generate the 16.6mWh of electricity and 17 tons of carbon dioxide emissions per ton of aluminium produced.

“The ShAPE manufacturing process conserves energy and eliminates greenhouse gas emissions on several fronts,” said Whalen. “First, we avoid the need to add primary aluminium. Then, we eliminate the need for what is called homogenisation of the billet material, a six- to 24-hour heat treatment near 500°C prior to extrusion.”

In addition, eliminating the need to add newly mined aluminium greatly reduces the manufacturing cost, opening the door to a larger market for what has been considered lower-grade “twitch” aluminium scrap. 

This kind of scrap is composed of an ever-changing mix of manufacturing scrap and post-consumer goods such as the ubiquitous beverage cans, but also all manner of used house siding, window and door frames, step ladders and a myriad of used equipment of all sorts.

“Creating a circular market that provides a value proposition for this twitch scrap opens up the possibility for new industrial uses in the building industry, among sporting goods manufacturers, auto parts, and framing for emerging industries such as solar panel manufacturing,” said Donsky.

Atomic13 is currently in the design phase of its first commercial manufacturing line with a leading equipment company in the extrusion industry and is also evaluating site locations in the Midwest and Southeast. 

The company is in discussions with builders and construction companies interested in sustainability and the decarbonisation of building materials and plans to accept orders by early 2025.

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