HSLU Optimizes Metal Recycling AI Turns Scrap Into Valuable Material

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In Switzerland, nearly two million tons of scrap metal are generated annually. However, much of it is insufficiently sorted and therefore poorly recycled: instead of being used in vehicle manufacturing or the machinery industry, it often ends up as construction material. Two studies by the Lucerne University of Applied Sciences and Arts now show how this "downcycling" can be avoided through intelligent technologies and new approaches, and how high-quality metal can once again be produced from scrap.

Up to 95 percent of metal scrap in Switzerland ends up in recycling plants. Sounds good, but it’s not necessarily so. "The return rate alone says nothing about the quality of the recycling," says Prof. Dr. Simon Züst, research group leader of two studies on the subject at the Lucerne University of Applied Sciences and Arts (HSLU).

While the scrap is processed further, it can no longer be used for high-quality applications due to impurities—such as copper from cables or tin from can coatings.

An example: Copper in steel scrap can no longer be removed during melting. Even the smallest amounts affect material properties such as malleability and weldability. The resulting recycled steel is no longer suitable for safety-critical components in vehicle manufacturing or for precise machine components. Instead, it ends up in civil engineering, for example, as steel reinforcement (rebar) in concrete, where lower requirements for quality and purity apply.

This so-called downcycling is not only economically unattractive but also strategically problematic: Switzerland has no economically viable ore deposits. "Every ton that is recycled at a high quality strengthens our independence from imports," emphasizes Züst. This is a particularly relevant factor in times of trade and economic instability.

Sensors Identify Metal Scrap Even Before Processing

In the ReRe Circular Economy for Metals project, the research group examined, among other things, the role that intelligent sensors combined with self-learning AI can play at collection points when it comes to detecting the material composition of metal scrap. They can identify critical components such as batteries or pressure vessels, enabling precise and safe sorting.

This not only increases the efficiency of recycling but also its ecological and economic benefits: according to Züst, if just 15% of returned metal scrap were recycled in higher quality, up to 40,000 U.S. tons of CO₂ could be saved annually, and an added value of around 30 million francs ($33 million) per year could be generated. The effect is also significant for other metals such as aluminum, zinc, or copper, according to the "International Copper Association (2022)": cleanly recycled copper, for example, retains around 95 percent of its material value, as it can be reused almost losslessly. Currently, only about half of Europe's copper demand is met through recycling, so there is still room for improvement.

Systemic Approaches: Rethinking Cycles

The second project, Reinvent, funded by Innosuisse, examined the overall metal recycling system: from material flows to stakeholders to business models. The aim of the study was to lay the foundation for a connected, future-proof circular economy for metals in Switzerland.

In addition to technological innovations, binding quality standards, reliable data for traceability, and economic incentives for companies involved in metal processing, scrap generation, or collection logistics and processing are necessary. For example, a key factor is recyclers' understanding of the added value of clean recycling. Only when this value is recognized will the willingness and motivation to invest in measures such as optimized sorting processes increase. Bonus models for particularly sustainable practices are also conceivable. Züst remains optimistic: "The industry is open and ready for innovation."

Defined Key Areas for Action

The two studies by the Lucerne University of Applied Sciences and Arts provide a concrete foundation for making the metal cycle in Switzerland future-proof, resilient, and less dependent on imports. To make high-quality recycling the norm, the researchers recommend, among other things, integrating sensor technologies on a large scale, establishing standardized data systems for traceability, and strengthening collaborations along the value chain. Reuse strategies should also be considered and promoted technologically, economically, and regulatorily throughout the entire system. For Züst, it is clear: "High-quality recycling is not a compromise but a key to the sustainable raw material supply of tomorrow."

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