Scarce metals such as tin, silver, tungsten and indium are used in most electronic equipment and are both rare and difficult to extract since the workable concentrations are very small. This ensures the metals are highly sought after – and their extraction is a breeding ground for conflicts, such as in the Democratic Republic of the Congo where they fund armed conflicts.
In addition, they are difficult to recycle profitably since they are often present in small quantities in various components such as electronics.
Rickard Arvidsson and Björn Sandén, researchers in environmental systems analysis at Chalmers University of Technology, have examined an alternative solution: substituting carbon nanomaterials for the scarce metals. These substances – the best known of which is graphene – are strong materials with good conductivity, like scarce metals.
“Now technology development has allowed us to make greater use of the common element carbon,” says Sandén. “Today there are many new carbon nanomaterials with similar properties to metals. It’s a welcome new track, and it’s important to invest in both the recycling and substitution of scarce metals from now on.”
The Chalmers researchers have studied the main applications of 14 different metals, and by reviewing patents and scientific literature have investigated the potential for replacing them by carbon nanomaterials. The results provide a unique overview of research and technology development in the field.
According to Arvidsson and Sandén there is already a shift away from the use of scarce metals to carbon nanomaterials taking place.
“There are potential technology-based solutions for replacing 13 out of the 14 metals by carbon nanomaterials in their most common applications. The technology development is at different stages for different metals and applications, but in some cases such as indium and gallium, the results are very promising,” Arvidsson says.
“This offers hope,” says Sandén. “In the debate on resource constraints, the focus has long been on recycling and reuse. Substitution is a potential alternative that has not been explored to the same extent and as the resource issues become more pressing, we now have more tools to work with.”
The research findings were recently published in the Journal of Cleaner Production. Arvidsson and Sandén stress that there are significant potential benefits from reducing the use of scarce metals, and they hope to be able to strengthen the case for more research and development in the field.
