Realising Advanced Sensor Technology for Enhanced Recovery of Metal Scrap (RASTER)

A growing global population and the rising demand for consumer products is imposing severe pressures on our dwindling natural resources. Combined with other global challenges such as climate change and food security, this failure to manage resources seriously undermines the likelihood of a sustainable future. It is widely recognized that we need to adopt a circular-economy, where used and discarded products are recycled, their materials recovered and re-used to become the feedstock for the new.

For example, end-of-life vehicles, waste electrical and electronic equipment, and white goods all contain substantial quantities of valuable metals, such as aluminium, copper, brass, lead, magnesium, nickel, tin and zinc, which can profitably be recovered and returned to the supply chain. Materials recovery facilities however, face a tough market place with disruption from national and international policies, trade barriers, and resource volatility. Against these challenges, recyclers are having to re-examine their mixed metal products. There is now a real need for more effective sorting technologies, driving investment to improve efficiency, capacity, yields, and quality of the recyclate, while minimizing the residue set for landfill.

This proposal aims to develop new science and concepts to drive a new generation of electromagnetic and induction-based non-ferrous metal separation technologies. Induction sorters, essentially metal detectors, are already in common use in recovery facilities to extract low-conductivity metals such as stainless steel. This project mobilizes our research in electromagnetic inspection, developed from work across a range applications as diverse as food testing to detection of landmines, to deliver a new class of these kinds of sensors - 'smart' induction technologies which use multi-frequency analysis, new theoretical magnetic scattering approximations, and visual information to classify and separate a much wider set of non-ferrous metals with higher recyclate purities and efficient recovery relative to cost.

For example, in our previous work we showed that a multi-frequency induction design could achieve effective separation performance for some of the most common non-ferrous metals seen in end-of-life vehicles shredded waste - metals such as copper, aluminium and brass. The success of this simple innovation over standard induction technology has led us to partner with a leading UK magnetic separation equipment manufacturer to develop a commercial sorting solution.

This project is the next major initiative in our research strategy, focusing on new approaches for materials characterization to disrupt induction separation in resource recovery. We set out a plan to explore new theoretical insights in magnetic scattering approximation, such as the magnetic polarizability tensor, expanding on this work by developing fast and efficient approaches that deal with the demanding through-put and conditions of metal recovery. We will demonstrate these new approaches using an experimental platform emulating the key features of an industrial material separation rig to obtain relevant and realistic performance statistics. Our goal is for the new science and results that emerge from this research will impact how electromagnetic sensors are used in resource recovery, potentially enabling new high-throughput and lower-cost separation technologies that support a more profitable and buoyant recycling economy.