Rare earth elements (REEs) are a small, but incredibly powerful, family of metals that have an integral role to play in the manufacture of a multitude of modern electronic devices.
The unique magnetic, electrochemical and luminescent properties of REEs are being put to work in all manner of electronic applications - from smartphones, hard disk drives and electric vehicles to military defence systems, clean energy and medical equipment.
Currently, the majority of REE production is concentrated in just two countries - China and Australia - with China being by far the greatest producer, accounting for 85% of total worldwide production and Australia around 10%.
As the use of these new technologies becomes more prevalent, however, the demand for rare earth metals is only going to increase.
A 2017 study from the University of Science and Technology in Beijing has estimated that global demand for REEs could reach a staggering 51.9 thousand metric tonnes by 2030.
And the same study also predicted that there may only be sufficient resources to sustain global REE production at the current pace for another hundred years.
What are rare earth elements?
In all there are seventeen REEs, fifteen of which form part of what is known as the lanthanide series, making up the atomic numbers 57 to 71 consecutively on the periodic table.
Here are just a few examples of REEs and how they're being used:
- Cerium - the most abundant of the rare earth elements, used in magnets, electrodes and carbon-arc lighting, as a catalyst in catalytic converters and for precision glass polishing
- Neodymium - a soft silvery metal used to create strong permanent magnets for computer disks, microphones and headphones and in the production of powerful infrared lasers
- Dysprosium - one of the most highly magnetic elements used in the manufacture of electronics, computer disks, lasers, commercial lighting and energy-efficient vehicles
- Terbium - a soft, silvery metal used as an additive in rare earth magnets, in some electronic devices and in sonar systems
- Holmium - another rare earth element with powerful magnetic properties, used in the microwave equipment and nuclear control rods
- Lanthanum - a highly reactive rare earth element used in the manufacture of telescope lenses and infrared absorbent glass
- Scandium - used in the manufacture of popular consumer products such as televisions and energy-saving lamps
- Yttrium - a silvery metal found in superconductors, lasers, and surgical supplies.
What makes a rare earth element 'rare'?
The term 'rare' is really a bit of a misnomer because REEs actually exist in abundance.
Even the rarest of REEs (thulium) is still 125 times more prevalent in the earth's crust than gold - and the most prolific REE (cerium) is 15,000 times more abundant.
The key difference though is that REEs aren't found in solid clumps or seams but instead are unevenly distributed over the earth's crust - which makes them much more challenging to mine than other metals.
Chemically, it's also harder to separate one REE from another in order to obtain a pure substance.
In a nutshell, REEs are expensive to produce.
The rare earth metal europium for example - which is used in the production of computer monitors and plasma TVs - is currently selling for around £580,000 per metric tonne, and that price is steadily on the rise.
Reclaiming and reusing REEs
Demand for REEs is growing - but they're also a limited resource with at present no viable alternative methods to replace them.
One possible solution is to reclaim and reuse the rare earth metals present in products that have reached the end of their useful life.
Surprisingly though, the Rare Earth Technology Alliance has estimated that currently less than one-percent of the world's rare earth metals are presently being recycled - with the majority of REEs ending up in landfill.
But a new research scheme, is hoping to change this.
The EU's Horizon 2020 research and innovation programme has awarded funding to the tune of £12.98 million to industry-based consortium Sustainable Recovery, Reprocessing and Reuse of Rare-Earth Magnets (SUSMAGPRO).
In turn, SUSMAGPRO have allocated £4.35 million of their funding to a research team at Birmingham University.
Their plan? To find a way to successfully extract and reuse the rare earth metals from rare earth magnets.
Rare earth magnets are powerful permanent magnets that are used in practically every application that relies on electricity to produce motion - from electric vehicles and hard disk drives to an array of common household appliances.
Researchers at Birmingham University say they are confident of developing new technology that will be capable of producing around twenty tonnes of recycled rare earth magnets every year.
And, all going well, the new scheme is expected to dramatically reduce the quantity of REEs currently going to landfill, to offer a more sustainable solution to the growing challenges of REE extraction and to provide a greater layer of protection for the European REE supply chain.