Cristina Pozo-Gonzalo, Deakin University
Rare-earth metals are
critical to the high-tech society we live in as an essential component of
mobile phones, computers and many other everyday devices. But increasing demand
and limited global supply means we must urgently find a way to recover these
metals efficiently from discarded products.
Rare-earth metals are
currently mined or recovered via traditional e-waste recycling. But there are
drawbacks, including high cost, environmental damage, pollution and risks to
human safety. This is where our ongoing research comes
Our team in
collaboration with the research centre Tecnalia in Spain has developed a way to use environmentally
friendly chemicals to recover rare-earth metals. It involves a process called
“electrodeposition”, in which a low electric current causes the metals to
deposit on a desired surface.
This is important
because if we roll out our process to scale, we can alleviate the pressure on
global supply, and reduce our reliance on mining.
believe in experts. We believe knowledge must inform decisions
The increasing demand
for rare-earth metals
Rare-earth metals is
the collective name for a group of 17 elements: 15 from the “lanthanides
series” in the periodic table, along with the elements scandium and yttrium. These
elements have unique catalytic, metallurgical, nuclear, electrical, magnetic
and luminescent properties.
The term “rare” refers
to their even, but scarce, distribution around the world, noted after they
were first discovered in
the late 18th century.
These minerals are
critical components of electronic devices, and vital for many green technologies; they’re in magnets for
wind power turbines and in batteries for hybrid-electric vehicles. In fact, up
to 600 kilograms of rare-earth metals are required to operate just
one wind turbine.
The annual demand for
rare-earth metals doubled to
125,000 tonnes in 15 years, and the demand is
projected to reach 315,000 tonnes
in 2030, driven by increasing uptake in green technologies and advancing
electronics. This is creating enormous pressure on global production.
Can’t we just mine for
more rare metals?
are currently extracted through
mining, which comes with a number of downsides.
First, it’s costly and
inefficient because extracting even a very small amount of rare earth metals
requires large areas to be mined.
Second, the process
can have enormous environmental impacts. Mining for rare earth minerals
generates large volumes of toxic and radioactive material, due to the
co-extraction of thorium and uranium — radioactive metals which can cause
problems for the environment and human health.
Third, most mining for
rare-earth metals occurs in China, which produces more than 70% of
global supply. This raises concerns about long-term availability, particularly
after China threatened to restrict its
supply in 2019 during its trade war with the US.
E-waste recycling is
not the complete answer
recycling, rare-earth metals can be recovered from electronic products such as
mobile phones, laptops and electric vehicles batteries, once they reach the end
of their life.
recovering them from electric vehicle batteries involves traditional
hydrometallurgical (corrosive media treatment) and pyrometallurgical (heat
treatment) processes. But these have several drawbacks.
energy-intensive, involving multiple stages that require high working
temperatures, around 1,000℃. It also emits pollutants such as carbon dioxide, dioxins
and furans into
hydrometallurgy generates large volumes of corrosive waste, such as highly
alkaline or acidic substances like sodium hydroxide or sulfuric acid.
processes are also applied to other energy storage technologies, such as
lithium ion batteries.
Why our research is
challenges, we set out to find a sustainable method to recover rare-earth
metals, using electrodeposition.
already used to recover other metals. In our case, we have designed an
environmentally friendly composition based on ionic liquid (salt-based) systems.
We focused on
recovering neodymium, an important rare-earth metal due to its outstanding
magnetic properties, and in extremely
high demand compared to other
rare-earth metals. It’s used in electric motors in cars, mobile phones, wind
turbines, hard disk drives and audio devices.
liquids are highly stable, which
means it’s possible to recover neodymium without generating side products,
which can affect the neodymium purity.
The novelty of
our research using
ionic liquids for electrodeposition is the presence of water in the mix, which
improves the quantity of the final recovered neodymium metal.
reported methods, we can recover neodymium metal without using controlled
atmosphere, and at working temperature lower than 100℃. These are key considerations to
industrialising such a technology.
At this stage we have
proof of concept at lab scale using a solution of ionic liquid with water,
recovering neodymium in its most expensive metallic form in a few hours. We are
currently looking at scaling up the process.
An important early
In time, our method
could avoid the need to mine for rare earth metals and minimises the generation
of toxic and harmful waste. It also promises to help increase economic returns
method could be adapted to recover metals in other end-of-life applications,
such as lithium ion batteries, as a 2019 report projected
an 11% growth per annum in production in Europe.
Our research is an
important early step towards establishing a clean and sustainable processing
route for rare-earth metals, and alleviating the pressures on these critical