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Rare Earth Elements: Critical Developments in Harvesting from Waste


The Mountain Pass Rare Earth Mine & Processing Facility in the United States.  ©Tmy350/Wikimedia (CC BY-SA 4.0)
The Mountain Pass Rare Earth Mine & Processing Facility in the United States. ©Tmy350/Wikimedia (CC BY-SA 4.0)

From electric vehicles and wearable technology to artificial intelligence and smart cities—the modern world is becoming increasingly complex.


But what underpins it all are a handful of materials—called rare earth elements (REEs)—that are taken from the Earth. Without them, the trappings of modern life could never exist.


The challenge is to collect these materials in a way that is reliable and doesn’t harm people or the environment. Mining carries its own inherent problems, so the idea of recycling REEs is being seriously (re)considered.


Modern Technology Relies on REEs


Rare earth elements refer to a set of seventeen metallic elements; these include fifteen consecutive elements in the periodic table from lanthanum to lutetium, plus scandium and yttrium.


These metals form critical components of modern items ranging from computer hard drives and smartphones to catalytic converters in cars and the fiber-optic cables that make the Internet itself function.


They’re also vital in the move towards green technology, as they provide key components in high-powered magnets and rechargeable batteries that electric vehicles and other renewable technology rely on.


Prof. Simon Jowitt.  ©Mark Smith
Prof. Simon Jowitt. ©Mark Smith

With REEs in widespread use since the 1950s, the REE market size has reached around $9.5 billion in 2022. It is projected to more than double, to $20.9 billion, by 2028.


The REE industry, however, faces two quandaries—geopolitics and the negative impact of REE excavation on the environment. To deal with these dilemmas, a new generation of recycling methods—including one that has been used to make decaffeinated coffee—is being developed to provide more ways to harness the power of these metals.


“The desire, and in fact need, to recycle the rare earths is probably greater than ever for a variety of reasons,” said Prof. Simon Jowitt, associate professor at the Economic Geology Department of Geoscience at the University of Nevada.


“We've seen some progress in this area, but the fact is that we mine more rare earth elements than ever before, and they are crucial for the development of low and zero CO2 energy generation.”


Challenges to Extracting Rare Elements

Despite the use of “rare” in their name, REEs are actually quite plentiful in terms of their abundance in nature. Unfortunately, they are “rarely,” if ever, found in sufficient amounts in any one place. Extracting them is labor intensive and can have a negative impact on both the environment and human health.


For instance, the REE mining process can require toxic chemicals and create waste gas, wastewater, dust—and even radioactive residue—that can contaminate groundwater, land, and waterways. Exposure has also been associated with illnesses such as endomyocardial fibrosis and anemia.


The [REE] mining process can require toxic chemicals, and create waste gas, wastewater, dust—and even radioactive residue—that can contaminate groundwater, land, and waterways.

Geopolitical Concerns

Another pressing concern for Western governments and industry alike is China’s oversized role in REE production and the impact of global tensions.


Although China has only about one-third of the world’s rare earth reserves, it has the bulk of the world’s REE mining operations. China now accounts for “60% of global rare earth mined production, 85% of rare earth processing capacity, and over 90% of high-strength rare earth permanent magnets manufactured,” wrote a professor at De LaSalle University in Manila, Philippines.


By contrast, the US only has one REE mine, The Mountain Pass Rare Earth Mine and Processing Facility, in California, near the Nevada border. Recently, REEs were discovered in Brook Mine in Wyoming. The Biden administration has stated that mining domestic sources of rare earth elements is a matter of national security in terms of securing supply chains.


“China does have significant control on rare earth element mining—although this is decreasing with mining now occurring in the US and Australia,” Prof. Jowitt told The Earth & I. “The Chinese government tried to restrict exports of the rare earth elements around 2009/2010, but this was ruled unlawful by the [World Trade Organization], and their export restrictions were removed, but only after a spike in rare earth element prices.”


With a limited number of new mining operations in the West and the associated negative impacts of mining on the environment and on human health, the idea of recycling the REEs that people already have would seem to make sense. But doing so is far from simple or straightforward.


Emerging REE Recycling Industry

REEs are often blended with other metals for use in electronic components, so separating them from the unneeded elements—and in big enough quantities—is where the bulk of the recycling challenge lies.


REEs are used in electronic components such as light-emitting diodes (LEDs).  ©Afrank99/Wikimedia (CC BY-SA 2.0)
REEs are used in electronic components such as light-emitting diodes (LEDs). ©Afrank99/Wikimedia (CC BY-SA 2.0)

Some recycling processes require the use of hazardous chemicals, such as hydrochloric acid, which somewhat defeats the purpose of avoiding negative impacts of REE mining. And recycling REEs is not always cost effective, since only small amounts of REEs are reclaimed at the end of the process.


But the demand for recycled REE is substantial. A study commissioned by Eurometaux predicts that between 45% (nickel) and 75% (lithium) of Europe’s clean-energy metal needs could be met through secondary supply (including recycling) by 2050. The REE metals recycling market itself also has a projected worth of $422 million by 2026.


Between 45% (nickel) and 75% (lithium) of Europe’s clean-energy metal needs could be met through secondary supply (including recycling) by 2050.

To help fulfill this demand while also avoiding negative environmental impacts, new methods of recycling are being tested and deployed.


Lessons Learned from Decaf Coffee, Fungi, and Magnets


One such method is to employ microorganisms, such as bacteria, fungi, and algae, to absorb rare earths into their cells and cause them to ferment.


Organisms such as Gluconobacter bacteria naturally produce gluconic acid that can pull rare earths in a fluid catalytic cracking catalyst. Such organic acids are less environmentally harmful than hydrochloric acid or other traditional metal-leaching acids. This type of technology is being developed by REEgain, a Czech-Austrian platform funded by the European Union.


Another strategy uses copper salts to pull the rare earths from discarded magnets, a method developed by a team led by Ikenna Nlebedim, a materials scientist at Ames National Laboratory in Iowa and the Department of Energy’s Critical Materials Institute (CMI). In one projection, “recovering the neodymium in magnets from U.S. hard disk drives alone could meet about 5% of the world’s demand outside of China.”


CMI researchers also developed a way to extract REE from the high-powered magnets in electronic waste. Due to the sensitivities about content stored on hard drives, they are usually shredded before being dumped. The new method takes the shredded mix and puts it in solution which targets just the magnet and leaves the rest of the components of the mixture undissolved.


Other researchers are pondering ways to extract REEs in a similar manner to how caffeine is extracted from beans to make decaf coffee.


That is what a team at the McKelvey School of Engineering at Washington University in St. Louis is working on. They developed a process using supercritical CO2 that has been used in industry to extract caffeine from coffee beans since the 1970s. They used it to recover REEs from coal fly ash, a fine, powdery waste product from the combustion of coal.


A pile of fly ash.  ©Mailtosap/Wikimedia. Public Domain
A pile of fly ash. ©Mailtosap/Wikimedia. Public Domain

Project leader Young-Shin Jun, professor of energy, environmental and chemical engineering, said: “Supercritical fluid is considered as a greener solvent, is less invasive to the environment and allows us to extract REE directly from solid waste without leaching and roasting raw materials, so less energy is required for our new process, which also produces less waste.”


Meanwhile, in Texas, Noveon Magnetics, which uses its proprietary technology to recycle REE magnets, is rolling out solutions at the commercial level.


The firm takes magnets that have reached the end of their useful life in tech, such as electric motors and MRI scanners, and recycles them. It claims eleven tons of CO2 emissions are saved for every ton of magnets it produces.


Scott Dunn.  ©Mark Smith
Scott Dunn. ©Mark Smith

CEO Scott Dunn told The Earth & I: “We use a material agnostic, dry powder metallurgical process that harvests bulk scrap or pure materials, converts those materials to a fine powder, presses the powder, bakes the material in a vacuum furnace, and then creates newly engineered rare earth magnets with higher magnetic flux, increased resistivity, and superior thermal stability.”


An Industry in its Infancy

Prof. Jowitt said that while there are interesting developments in recycling rare earth elements from waste material like mining waste or coal ash, there are significant issues to overcome.


“The Mountain Pass rare earth element deposit in California mines rare earth element ore at a grade of 8%—in other words, 8% of the ore mined is rare earth elements.


“The coal ash that some say could be a source of rare earth elements contains about 500 parts per million, or 0.05% rare earth elements, mainly lanthanum and cerium, the ones that we don't want.


“In other words,” he said, “you'd have to move 160 tons of coal ash to get the same amount of rare earth elements as a ton of ore mined at Mountain Pass. This has all sorts of logistical, transport, and emissions issues, so we need to think about how viable these alternative solutions really are.”


As with other nascent industries, there are challenges tied to workforce development and equipment fabrication, said Mr. Dunn of Noveon Magnetics. “As a result, we’ve had to design and build a lot of our own machinery to create our own degree of supply chain resilience against the centralized forces.”

 

*Mark Smith is a journalist and author from the UK. He has written on subjects ranging from business and technology to world affairs, history, and popular culture for the Guardian, BBC, Telegraph, and magazines in the United States, Europe, and Southeast Asia.

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