Technology critical metal recycling using ultrasonics and catalytic etchants

Technology critical metals (TCMs) are an essential distinct subset of specialist, often 'critical' metals, and each has its own specific properties. They are fundamental enablers of most major applications throughout industry and especially in clean energy and digital technologies, and they are essential for the world to decarbonise. The demand for TCMs is growing, and a wider range of materials and a circular economy approach are needed for the emerging technologies that will enable the energy transition and net zero aims. The UK is currently 100% import-reliant on TCMs and so it is essential to recycle these metals and develop a circular economy. Unfortunately these metals are diffusely distributed and maintaining value is difficult with current non-selective hydrometallurgical techniques. The vision of this research proposal centres on the use of targeted, catalytic etchants which can control the redox state of TCMs from complex architectures. This project will target layered structures such as photovoltaic and thermoelectric devices although it could equally be applied to a variety of other structures such as printed circuit boards and composites, particularly those of significant value to industries such as aerospace or wind renewables. The novelty of this project lies in combining catalytic etchants with ultrasonic techniques to bring about almost instantaneous separation and enable selective, fast-throughput processes to be developed. This project aims to develop a range of sustainable, inexpensive catalysts which can preferably be regenerated using air emulating what is done in a biological and geological environment. Practical recycling solutions need to be rapid and efficient and the secret to doing this for metals is to increase mass transport and change speciation. This project addresses the former using focussed ultrasound and the latter using novel ambient temperature ionic fluids.