They are not-so-rare, in fact they are everywhere. But they are hard to find and even harder to separate, and we need them more and more for our modern technologies.
“The rare-earth elements have been described as the most important resource of the 21st century,” explained Peter Junk, of the College of Science & Engineering, James Cook University, Queensland, Australia. “Their ubiquity in contemporary life coupled with the impact of the Chinese near monopoly of supply, vividly illustrated by their recent cut in exports and their ban on exports to Japan in 2010 has highlighted their strategic importance to business leaders and politicians, as well as scientists.”
Junk’s STIAS project is to write a comprehensive review of the rare earths.
The 17 rare earths are scandium, yttrium, lanthanum, cerium, praseodymium, neodymium, promethium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, lutetium – “Their names are a mouthful but give a hint of their chemistry or of where they were initially discovered or the person who discovered them,” said Junk.
“Many were initially found in Northern Europe – in particular Scandinavia – where they were used for flint from the 1700s. Ytterby outside Stockholm is an important town for these rare elements – the only place that has four elements named after it.”
They are mostly grey to silvery-coloured metals, soft, malleable and ductile but in different combinations can be both fluorescent and luminous in various colours.
“All occur naturally except promethium which is radioactive and made in a nuclear reactor.”
But it’s their use in so many modern technologies and gadgets that is increasingly making them a political hot potato globally. “50 years ago rare earths were not commonly mined but they now have an important place in modern technologies.”
They are found in things we use every day from bicycles, baseball bats and cigarette lighters, to iPods, LEDS, hybrid cars, lasers, magnetic resonance imaging (MRI), mobile phones, wind turbines, fibre optics and energy-efficient fluorescent light bulbs.
“MRI developed from a chemical technique – nuclear magnetic resonance,” explained Junk. “They dropped the nuclear bit for medicine. It’s basically a big magnet used to image soft body tissue. If you inject the rare earth gadolinium – which is the most magnetic element in the periodic table – into the body the big magnet can see it.”
“They are also used in fluorescent lights – particularly to create cool, white light. With the right properties, and excited by electric current, you can combine green, red and blue into white.”
So why rare?
But if they are found everywhere, why are they described as rare?
“Rare earths are not common but also not the rarest elements,” explained Junk. “They are available roughly equivalent to lead but more abundant than iodine. They are found all over the world but described as rare because they are not found in concentrated bodies – like other metals – so they are scattered and more difficult to find.”
“They are hidden because they don’t exist in large-concentrated ores and multiple elements will exist in one ore,” said Junk. “They are also difficult to extract and isolate.”
The separation procedure uses acid and kerosene. And, largely because of this complex and unpleasant process, China is the only country currently that has substantial rare-earth mining and extraction plants.
With the growing technology boom China started producing rare earths from the 1980s and by 2009 were producing 95% of the world supply. Initially China used their rare earths in their own electronic products and didn’t export to other producers like South Korea and Japan.
China’s dominance of the field allowed them to control prices effectively squeezing out other potential producers like the US. And there is money to be made with prices ranging from about $100 per kg for the more common rare earths to $1000s per kg for those harder to find and extract.
“China remains the major provider of rare earth elements worldwide currently, producing some 80% of all rare earth minerals. But more countries including the USA, Japan and Australia are looking for alternatives so access to these metals is not restricted.”
Junk explained that in about 2017 Australia became involved and is now responsible for about 15 – 20% of global production. Lynas Rare Earths is the only producer of rare earths outside China at present, but other Australian companies are moving into production soon. In Australia rare earths tend to be found close to the surface so extraction is easier but they are still experiencing problems in the separation process especially due to environmental concerns. He added that it’s possible to recycle the kerosene but not the acid.
“Australia has large rare earth reserves and is well placed to provide a reliable source of supply. Australian companies are also currently investigating further opportunities worldwide, in Africa and particularly Uganda,” he continued. “Mining and production is likely to begin soon and it’s anticipated that by 2025 Uganda could be producing 25 000 tons per annum.”
But there’s still a lot more we need to learn about rare earths and Junk outlined some of the research he and his colleagues are involved in ranging from understanding the fundamental chemistry of these elements to more applied research looking at ways of synthesising new chemical compounds and understanding how to transfer this into useful materials including corrosion inhibitors and luminescent compounds.
Junk highlighted the corrosion inhibitors. Developing these from organic molecules and rare earths could eventually replace the use of toxic chromium. Chromium was the subject of the 1987 class action case in Hinkley, California – later made famous by the 2000 film Erin Brokovitch – which concerned hundreds of cases of respiratory disease and cancers linked to chromium-contaminated effluent from a gas-compressor plant resulting in a settlement of US $333 million.
“Chromates are being phased out of commercial use,” explained Junk. “But corrosion costs about $250 billion per annum in the US alone, so we need new corrosion inhibitors. We are looking at rare earths which are non-toxic and could be used at much lower concentrations than other substances. Using combinations of rare earths and organic compounds we have been able to form an organic raft which forms a protective barrier stopping corrosion.”
The group is also looking at using rare earths to absorb UV light for luminescence as well as at harnessing their optical properties in safety equipment, LEDs and imaging.
In discussion, he talked about recycling explaining that it’s possible to recycle rare earths from larger applications like batteries and magnets but it’s harder in small technologies like mobile phones where tiny amounts of rare earths are used.
He also addressed the challenges of moving from academic research to marketable products. “Right now the industry is still quite fickle in Australia. The companies seem to want the universities to just hand over their research – they won’t invest heavily in it,” he said. “We started a rare-earth interest group but the mining companies didn’t come. But if we come up with something good they will hopefully flock to us then.”
Michelle Galloway: Part-time media officer at STIAS
Photograph: Ignus Dreyer