By Katharine Comisso – New Scientist – Published: October 29, 2010
For decades, the world has been busy incorporating the so-called rare earth elements into all manner of high-tech devices, including disc drives, wind turbines and hybrid cars. The messy business of mining the ore and extracting the elements was left to China, and few people in the west cared that the nation controlled 97 per cent of world supply.
“Rare earth” is an alternative name for the lanthanides – elements 57 to 71 – plus yttrium and scandium, and despite the name most of them were not considered rare at all. The elements hit the headlines a few weeks ago, when China appeared to be blocking exports to Japan and the US. The Chinese government, which has also been tightening its export quotas, claims that it needs to clean up mining procedures and support its own growing demand for rare earths.
So what can the rest of the world do about it? The most obvious course of action is to open mines elsewhere, since China accounts for little more than a third of known reserves. The biggest importer, Japan, is hoping to open a mine in Vietnam. And in the US, Molycorp Minerals plans to reopen its Mountain Pass mine in California, which has not been active since radioactive waste leaked from a pipe there in 2002.
However, facilities to refine rare earths cannot be created overnight, and few US scientists know how to do it anyway. “Even if Molycorp can get material mined and concentrated right now… it would have to send that material to China to get it refined,” says Gareth Hatch of Technology Metals Research, a consultancy firm in Carpentersville, Illinois.
Recycling is another option, but impurities sneak in during the process, so recycled materials are not always as good as the freshly refined equivalent. The neodymium magnets used in hybrid cars, for example, work less well at high temperatures when recycled neodymium is used.
Some items containing rare earths are reusable. The neodymium magnets in computer disc drives, for example, usually outlast the computer they are in, but disc drive manufacturers have till now found it cheaper to use new magnets than to reuse old ones.
The scarcity issue is being tackled in a different way by Kazuhiro Hono of Japan’s National Institute for Materials Science in Tsukuba. Dysprosium is one of the rarer rare earth elements, so Hono is reducing the amount of the element in the permanent magnets used in hybrid cars.
Hono hopes the crisis will encourage more scientists into the field. “The important thing is to recognise the importance worldwide,” he says. With efforts focused on innovation, he adds, “the solution to this problem will come out in the future”.