Aluminium recycling produces metal foam for industrial products Despite being highly recyclable, much aluminium still ends up in landfill. The ALFOAM breakthrough recycling technique helps close the production cycle by creating revenue streams from what would otherwise be waste. Industrial Technologies © MZeta, Shutterstock Aluminium has a range of properties attractive to a variety of industries, such as a good weight to strength ratio and resistance to corrosion. As such, it is increasingly popular with the aviation and automotive sectors, for example for lightweight electric vehicles. Over 50 % of aluminium is produced from waste materials such as aluminium scrap, which saves on natural resources such as bauxites, the principle source of aluminium. As recycled aluminium only uses 5 % of the energy needed to produce primary aluminium, it also saves on energy. However, there is still significant aluminium wastage (approximately 5.343 million tons) which ends up in landfill annually. Under the ALFOAM project, EU support helped Createc, the project host, undertake a feasibility study for a breakthrough technology which reuses aluminium which would otherwise be unrecyclable. The technique produces aluminium foam panels, of interest to vehicle parts manufacturers, designers and architects. The foam panels The ALFOAM team developed a process for manufacturing products made from metal foams directly from aluminium scrap, such as extruded profiles. These metal foams, formed with gas-filled pores, are strong and durable, and can be flexibly adapted to a variety of needs. While processing large pieces of aluminium scrap is fairly straightforward, smaller sizes are more problematic and uneconomical as they usually burn away during melting. What makes the ALFOAM process unique is that it doesn’t rely on melting the scrap, and uses much less energy, making it more environmentally friendly. “We started by developing a technique to process smaller waste pieces, but as a result of our experiments, completely by accident, we found our efforts were producing aluminium foam, and so we have exploited that to develop our proprietary technique,” explains project coordinator Maciej Nowosielski. Firstly, the scrap is selected and sorted to remove steel, plastic and other impurities. Next, the scrap is compacted to form pastilles which then undergo two strictly controlled operations for extrusion: shaping into a semi-finished product, and foaming. Lastly, ALFOAM’s proprietary technique is applied to form the final aluminium foam, as a material for further products. So far, compacting, extrusion and foaming trials have been conducted at the semi-industrial scale. The team also conducted trials with different input materials, for example chips from different machining processes, such as milling, polishing and cutting. In cooperation with partners, the team were able to verify that the technology was scalable. The flexible solution The ALFOAM solution could contribute to better management of difficult-to-process waste, reducing its overall volume, while also indirectly reducing the amount of waste released into the atmosphere as ash from the melting process. For a waste-generating company, the technology will not only reduce the cost of disposal, but also generate additional revenue from the sale of valuable metallic foam. The team are now continuing to adapt the technology for the recycling of other materials, with particular attention paid to aluminium alloys. In addition to the architecture, building and public transport sectors, they are also working with a leading manufacturer of wheeled armoured personnel carriers to explore the possibility of entering that market. “The immediate next step is to get the technology ready for early adopters. After that, we will develop longer-term strategies, maybe looking for an external investor to accelerate development,” says Nowosielski. Keywords ALFOAM, aluminium, metallic foam, waste, recycle, bauxites, alloys, extruded profiles
