Aluminium Scrap: A Promising Technology

Post-consumer recycled aluminium scrap is transformed into new building materials

(Credit: Andrea Starr, Pacific Northwest National Laboratory)

Twisted aluminium mesh, broken bicycle frames and used car parts languishing in junkyards could gain new life as building structures such as door and window frames thanks to a new recycling technique.

Based on a patent-pending technology developed at the US Department of Energy’s Pacific Northwest National Laboratory (PNNL) in Washington state, the new process could reportedly provide energy savings of almost 90% when making aluminium building components.

“Strong yet lightweight aluminium parts are being deployed more often as building materials,” a PNNL announcement said. “But there’s a high energy and greenhouse gas emissions cost to mining and refining aluminium.”

According to the International Aluminium Institute, the production of 1 ton (0.9 tonnes) of primary aluminium emits an average of 17 tons (15.4 tonnes) of carbon dioxide into the atmosphere.

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

“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,” the announcement said.

The manufacturing process deforms scrap aluminium bricks or rod-shaped billets using high shear forces to ‘pulverise’ impurities in scrap aluminium into tiny particles, uniformly dispersing them within the aluminium microstructure.

The dispersion eliminates microscopic iron clumps that can generate microfractures in recycled aluminium products manufactured using conventional methods, the PNNL team said.

ShAPE aluminium extrusion could provide considerable energy savings, the announcement said, by eliminating the need to dilute impurities found in recycled aluminium with 25-40% newly mined aluminium before processing.

“The ShAPE manufacturing process conserves energy and eliminates greenhouse gas emissions on several fronts,” said PNNL chief scientist Scott Whalen, who led the research. “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.”

He added: “With approximately 55% 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.

“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.”

Founded by entrepreneur Eric Donsky, manufacturing start-up Atomic13 aims to commercialise the technology and create custom-extruded parts for building and consumer products.

“ShAPE technology enables companies like Atomic13 to produce aluminium extrusions made from 100% post-consumer scrap with 90% lower carbon,” Donsky said. “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.”

Source: I.meche