Recycling Rare Earth Metals Presents Challenges, Opportunities
Few things have had as big an impact on modern technology as rare earth elements (REEs). Sometimes called rare earth metals (REMs), these are a group of 17 related elements which, despite their name, can be surprisingly abundant. They are found in a huge swath of technologies, including smartphones, TVs, light bulbs, glass, hybrid and electric vehicle batteries, steel and aluminum (as strengthening agents), medical and dental devices (including x-rays, MRI machines, and surgical lasers), wind turbines and other clean technologies, and so much more.
As ubiquitous as REE usage is, the supply chain for them is fairly limited. With fears of a possible shortage looming in the near future, researchers and businesses are looking for ways to cost-effectively reclaim and recycle REEs.
Many REEs are found throughout the world, including large deposits in the U.S., Brazil, Australia, South Africa, and many parts of Asia. However, today more than 95 percent of all REE production is in China, where low labor costs and lax regulations make it difficult for other countries to compete.
In June of 2012, China released a white paper explaining how current veins of REEs were running low, and that production would be ramped down. Naturally, industries that depend on these metals shuddered. China has been playing games with its rare earth supplies, restricting exports and driving up prices, and then announcing huge quota increases following pressure from the World Trade Organization.
Currently the country is stockpiling the metals in anticipation of low production output. Despite this, prices of REEs have actually been dropping since April 2011, but businesses that depend on these metals don’t trust they will stay that way.
How to Reclaim
Recycling REEs sounds like an obvious route. But it’s not necessarily an easy one. For starters, rare earths are typically used in small amounts in electronics, medical, and similar applications — often less than one gram. But the other challenge is handling.
Larry Jones, an associate scientist at U.S. Department of Energy (DoE) Ames Laboratory, told the Iowa State Daily, “Air reactivity makes it difficult to work with [rare earth metals] because … if you took a small chunk of it and left it out in the air on a workbench in the lab, come back tomorrow morning, it’ll be a pile of powder.”
At present, there is no standard method of recycling rare earths. Several years ago, Japanese mining company Dowa began harvesting circuit boards, hard drives, computer chips and other components for rare earth metals. According to a 2010 New York Times article, the company cuts the components into 2 cm squares and then smelts them at 1,400 degrees C. But 300 tons of e-waste results in a mere 150 grams of REEs. Still, company claims to turn a profit on the operation, though it’s more likely due to the large amounts of gold, silicon, and other materials that can also be extracted from e-waste.
Jones of Ames Laboratory is developing a method of isolating REEs from magnets using molten magnesium. The process isn’t actually new — it was developed by Iowa State University in 1990 to create a magnesium-neodymium alloy and was used with raw neodymium. But the current research aims to extract it and other rare earths from scrap.
The Ames process breaks the rare earth magnets into 2 mm to 4 mm long pieces, which are added to a crucible with solid magnesium. A radio frequency furnace heats the magnesium until it liquefies, at which point the REEs diffuse into the molten metal, leaving behind base materials like iron and boron. The molten mixture is cooled and cast, only to have the magnesium boiled off again so that only the REEs remain.
Researchers from the University of Leuven in Belgium are using ionic liquids to separate rare earths from transition metals in rare-earth magnets. The process uses trihexyl(tetradecyl)phosphonium chloride to remove transition metals like iron, cobalt, magnesium, and copper into a liquid phase, leaving the rare earths behind in an aqueous state.
Honda has also developed a method of using molten salt to extract rare earths from nickel-metal hydride batteries used in hybrid vehicles. The process has been tested on the 386 Honda hybrids that were damaged in the Great East Japan Earthquake on March 11, 2011. The company claims the extracted metals have 99 percent purity and that as much as 80 percent of REEs in nickel-hydride batteries can be reclaimed this way.
There are those who believe that the best way to make REE recycling is to consider reclamation in the initial product design. Two reports by the United Nations Environmental Program (which you can find here and here) speak to this approach. Achim Steiner, executive director of the UNEP, said at a conference in Berlin last month, “Product designers need to ensure that materials such as rare earth metals in products ranging from solar panels and wind turbine magnets to mobile phones can still be recovered easily when they reach the end of their life.”
Still, some groups are looking to find ways to avoid using REEs at all. In particular, as we reported last year, automakers are looking to break free of their dependence on neodymium and lanthanum. Up to 10 pounds of the latter can be found in a Toyota Prius. Electronics manufacturer Philips announced in April 2012 that it sought a substitute to yttrium in its LED (light-emitting diode) products.
Of course, as prices rise and China becomes less competitive, some mining companies have looked to reopen old rare earth mines. Molycorp announced in August 2012 that it has resumed operations of the California Mountain Pass on a start-up basis. Mountain Pass had once produced the majority of the world’s rare earths before being shuttered in 2002 due to mounting environmental restrictions and a drop in prices for REEs.
But others are looking for new sources of rare earths. Japanese researchers have discovered high amounts of REEs in the seabed around Minamitori Island. Reports claim the deposit holds 20 to 30 times the amount found in Chinese mines. Unfortunately, extracting them could be cost prohibitive, and studies still need to be done to minimize the impact on the local marine ecosystem.
REEs can also be found in another hard-to-reach place: Outer space. At the Off-Earth Mining Forum in Sydney, Australia this past March, scientists speculated about the possibilities of mining asteroids or even the moon. Here the speculation was less about feasibility — all the necessary technology exists and is fully commercial — than cost-competitiveness.
And cost competition, as you may remember, is what got us into this mess.