Summary:
Scarce metals are found in a wide
range of everyday objects around us. They are complicated to extract, difficult
to recycle and so rare that several of them have become "conflict
minerals" which can promote conflicts and oppression. New research shows
that there are potential technology-based solutions that can replace many of
the metals with carbon nanomaterials, such as graphene.
Scarce metals are found in a wide
range of everyday objects around us. They are complicated to extract, difficult
to recycle and so rare that several of them have become "conflict
minerals" which can promote conflicts and oppression. A survey at Chalmers
University of Technology now shows that there are potential technology-based solutions
that can replace many of the metals with carbon nanomaterials, such as
graphene.
They can be found in your computer,
in your mobile phone, in almost all other electronic equipment and in many of
the plastics around you. Society is highly dependent on scarce metals, and this
dependence has many disadvantages.
Scarce metals such as tin, silver,
tungsten and indium 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 now 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
the summary shows that a shift away from the use of scarce metals to carbon
nanomaterials is already 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, circular economy and
society's handling of materials, 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.
"Imagine being able to replace
scarce metals with carbon," Sandén says. "Extracting the carbon from
biomass would create a natural cycle."
"Since carbon is such a common
and readily available material, it would also be possible to reduce the
conflicts and geopolitical problems associated with these metals,"
Arvidsson says.
At the same time they point out that
more research is needed in the field in order to deal with any new problems
that may arise if the scarce metals are replaced.
"Carbon nanomaterials are only
a relatively recent discovery, and so far knowledge is limited about their
environmental impact from a life-cycle perspective. But generally there seems
to be a potential for a low environmental impact," Arvidsson says.
Facts:
Carbon nanomaterials consist solely
or mainly of carbon, and are strong materials with good conductivity. Several
scarce metals have similar properties. The metals are found, for example, in
cables, thin screens, flame-retardants, corrosion protection and capacitors.
Rickard Arvidsson and Björn Sandén
at Chalmers University of Technology have investigated whether the carbon
nanomaterials graphene, fullerenes and carbon nanotubes have the potential to
replace 14 scarce metals in their main areas of application (see table in
attached image). They found potential technology-based solutions to replace the
metals with carbon nanomaterials for all applications except for gold in
jewellery. The metals which we are closest to being able to substitute are
indium, gallium, beryllium and silver.
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