A new process makes it easier to recycle the chemical elements used to make the strongest permanent magnets. These rare earth magnets are used in hard drives and EV motors. Beyond their use in magnets, rare earth elements are used in lasers, glass, electronics, and a host of other applications important to modern daily life. They are expensive to mine and separate, and have long been a geopolitical football in trade wars, including the current one between the United States and China.
Compared with existing methods to recover rare earth elements, a process based on rapidly heating waste magnet material in the presence of chlorine gas uses one-third of the processing steps, reduces energy consumption by 87 percent, and produces 84 percent fewer greenhouse gas emissions. That’s according to a life-cycle analysis done by researchers led by James Tour, a chemist at Rice University. Their process is described in a recent paper in the Proceedings of the National Academy of Sciences.
Rare Earth Elements in Electronics
Rare earth elements aren’t scarce, but they are complicated and expensive to produce. Consisting of many of the elements at the bottom of the periodic table, they are typically found in mixed deposits, and they are extremely challenging to separate from one another because they have very similar chemical properties. Separating them out for various uses is expensive and requires complex processing. China controls the supply of most of the planet’s rare earths, and also most of the world’s capacity to process and separate the minerals. Most of the rare earth magnets used in the United States are imported from China, Tour says.
Tour says countries like the United States have abundant supplies of the elements already separated out from one another—just in the form of electronic waste. “The waste materials have 100 to 1,000 times higher concentrations than are found in ores,” Tour says.
Existing methods for recycling rare earths require high temperatures, multiple stages of processing, and the use of harsh solvents and large amounts of energy. Tour compares his lab’s setup to a toaster oven, which uses electricity to rapidly heat a quartz tube under a slice of bread. Instead of a quartz tube, this reactor uses a sheet of carbon paper as the heating element, which can get much hotter, up to about 10,000 kelvins in one second (over 9,700 °C). Though the element gets incredibly hot, it happens in a very short amount of time, so the process, called flash joule heating, doesn’t require much energy.
The recycling technique begins with ground-up, demagnetized waste placed on the carbon paper and rapidly heated in the presence of chlorine gas. The separation process relies on simple chemistry—differences in the temperatures at which various metals readily react with chlorine. Rare earth oxides react with chlorine only when the temperature is above roughly 1,350 °C, but other metals in the magnets, called transition metals, react with chlorine at about 1,000 °C. The Rice group’s process uses flash joule heating to get temperatures up to about 1,000 °C, creating transition metal chlorides that will boil off, leaving behind rare earth elements that are about 90 percent pure.
So far, Tour’s group has tested the process with two of the most common rare earth magnet materials: samarium cobalt and neodymium iron boron. “You can take these magnets, pull the material back out, and it can go into a new magnet,” says Tour. This process could also make magnet manufacturing more efficient: When neodymium iron boron magnets are cut down to shape, over 70 percent of the starting material ends up as waste.
Tour says his simple process grew out of his work on graphene synthesis. In 2020, his team demonstrated that graphene can be produced by placing any carbon-based material between electrodes and rapidly heating it. A company that was spun out of his lab, called Universal Matter, uses flash joule heating to produce a tonne of graphene in a day, Tour says.
With support from the Defense Advanced Research Projects Agency, Tour’s lab began working on using flash joule heating to separate valuable metals from electronic waste. This work, which first focused on critical minerals including indium, gallium, and tantalum, has been licensed to Metallium, a mineral exploration company in Western Australia. The company is planning to open a flash joule heating plant to recover metals from electronic waste in Texas in December.
This article appears in the December 2025 print issue as “Toaster-like Process Recovers Rare Earths From E-Waste.”