The minerals and the microwave: a cautionary supply chain tale
Posted: September 04, 2025
The materials that power much of modern life are by now fairly familiar. Think of a smartphone: aluminum and nickel in the casing, lithium and cobalt in the battery and copper wiring connecting it all.
But a typical smartphone also contains dozens of more obscure minerals.
Gallium nitride is key to the semiconductors that run your phone’s LED display. An ultra-thin film of indium tin oxide registers the input of your fingertips. Under the surface, tantalum capacitors stabilize the voltage in your phone’s critical circuits.
Although they perform very different tasks, gallium, indium and tantalum have a few things in common. They are only produced in relatively small quantities. And much of their mining and processing is concentrated in a handful of countries, including China.
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The brittle supply chains of critical minerals
That concentration is becoming an issue as countries look to secure their own production of important technologies—particularly in the context of the green transition.
Many of these minerals are important not just for phones, but for other consumer electronics as well as renewable technologies. Gallium and indium are both used in solar panels, for instance.
U.S. solar manufacturing capacity has been rising as part of a growing push to re-shore critical manufacturing. The E.U. is promoting domestic battery production to reduce the car industry’s reliance on Asian suppliers.
But the fact remains that many of their critical components are still made elsewhere. The U.S. is fully reliant on imports for its supply of gallium, indium and tantalum—as well as a dozen other mineral commodities. It’s a similar story in Europe.
And many of these minerals’ supply chains originate in China. The U.S. is reliant on China and Canada for more than 50% of its imports of 19 important mineral commodities.[1]
For example, China produces some 70% of the world’s indium, and a quarter of U.S. imports. The mineral is mainly produced during zinc ore processing and, aside from LCD screens and solar cells, is also used in 5G network components and as a coating on data center cables. China is also home to nearly all primary production of gallium, which is similarly recovered as a byproduct of processing bauxite and zinc.
Gallium, in particular, perfectly illustrates the dangers of that set-up: China has banned all exports of it to the U.S. as part of the two countries’ ongoing trade war. Analysts at the Center for Strategic and International Studies warn that this is now “causing a gallium supply crunch that may soon impact key production lines”—not just for green energy but also the military industry, where gallium is used in advanced radar and missile defense systems.[2]
“Amid spiraling trade tensions with the United States, Beijing has brandished a new arsenal of economic weapons, with few proving more potent than its export controls on critical minerals,” the analysts wrote in July.
Recycling rare minerals with microwaves
What to do in the face of such obviously risky supply chains?
One approach is to explore mining and processing closer to home. A private company is now exploring a deposit in Montana that it says contains high grades of rare earths as well as gallium, although it is still working on environmentally sustainable methods to separate and process the minerals. In Utah, another mining outfit wants to tap the country’s largest known indium resource.
A more common approach has been to look at recycling. After all, materials like aluminum, cobalt and copper are already recycled out of electronic waste—one of the fastest growing waste streams in the world, producing more than 60 million tons each year.
Whether in a discarded phone or an end-of-life solar cell, however, the likes of gallium and indium are typically present only as tiny specks compared to more common materials. Filtering out these materials is more akin to finding the needle in the proverbial haystack.
Enter Terence Musho and Edward Sabolksky, a scientist and engineer at West Virginia University’s Department of Mechanical, Materials and Aerospace Engineering. They found a promising solution by co-opting a common household appliance: the humble microwave.
“In our recycling method, we first shred the electronic waste, mix it with materials called fluxes that trap impurities, and then heat the mixture with microwaves,” Musho explained their technology in a recent piece for The Conversation.
“The microwaves rapidly heat the carbon that comes from the plastics and adhesives in the e-waste. This causes the carbon to react with the tiny specks of critical materials. The result: a tiny piece of pure, sponge-like metal about the size of a grain of rice.”
By filtering out those grains, the pair have managed to pull about 80% of the gallium, indium and tantalum from electronic waste at purities between 95% and 97%.[3]
They say the method is safer and more sustainable than leaching metals out of waste with chemicals—or simply burning it to get at copper and other valuables, as happens frequently in poorer countries that receive much of Western electronic waste.
Other companies are also exploring alternatives to traditional large-scale industrial refining. In Texas, Australian company MTM Critical Metals plans to build a processing site capable of extracting materials including gallium, indium and gold from electronic scrap, using a two-step process that involves no mining or smelting, as well as minimal chemicals. The company says its advanced electrothermal process can recover more of these materials than traditional methods, and do so more sustainably.
The two West Virginia University researchers are also developing their method and plan to test it next on smartphone circuit boards, LED lights and server cards from data centers. Whether developers of novel recycling techniques will succeed in repurposing more of these rare minerals, at least one thing is certain: They're unlikely to run out of suitable waste anytime soon.
