Novel sustainable technique created for metal refinement

A new method has been developed to extract metals without requiring toxic solvents and reagents.

This novel system is less energy-hungry than current techniques and could reduce the environmental impact of producing metals from raw materials or post-consumer electronics. It takes advantage of mechanochemistry – an emerging branch of chemistry that relies on mechanical force instead of solvents and heat – by using stainless steel balls shaken at high speeds to aid purification.

Professor Jean-Philip Lumb, an associate professor at McGill University and co-author of the study, said: “At a time when natural deposits of metals are on the decline, there is a great deal of interest in improving the efficiency of metal refinement and recycling, but few disruptive technologies are being put forth. That's what makes our advance so important.”

The scientists’ initial experiment was to obtain germanium, a rare metal. The standard process of extracting it from ores requires numerous steps and harsh chemicals such as chlorine and hydrochloric acid to obtain germanium and zinc. The researchers extracted germanium at room temperature using a synthesised molecule with melanin-like properties. Further tests by the scientists discovered this process can be applied to other metals such as zinc, copper, manganese and cobalt.

Dr Tomislav Friš?i?, also from McGill University and co-author, said: “Combining elegant new chemistry with solvent-free mechanochemical techniques led us to a process that is cleaner by virtue of circumventing chlorine-based processing, but also eliminates the generation of toxic solvent waste"

The study was published in Science Advances.