Since their invention, rare earth permanent magnets have been used in automotive motors (small motors and now drive motors), consumer electronics, industrial applications, wind turbines, and many other products. With the growth of renewable and electric vehicle (EV) industries, the requirement for magnets and their raw materials has increased drastically.
NdFeB magnets are the strongest rare earth permanent magnets available and ideal for use in electric vehicles.
To meet the market demand more sustainably, governments and key players across industries are taking a greater interest in material recycling efforts. Recycling of rare earth permanent magnets creates a local, circular, independent supply chain without the devastating environmental impacts of conventional mining methods.
Permanent magnets in EV designs
According to Adamas Intelligence, more than 92% of EVs produced in 2021 used permanent-magnet synchronous motors (PMSM). These motors create torque using permanent magnets in the rotor to create a constant magnetic field that interacts with a varying magnetic field from the copper coils in the stator.
Compared to other motor types, PMSMs provide extremely high efficiency and torque density while minimizing heat losses. This leads to EVs that offer better driving performance using less energy. In general, the stronger a PMSM’s magnet, the more these benefits are maximized.
The strongest permanent magnets available are rare earth permanent magnets, called NdFeB magnets. Invented independently in 1984 by General Motors and Sumitomo Special Metals, NdFeB magnets have the highest Maximum Energy Product (MEP), meaning they can store the most magnetic energy per unit volume out of any known magnetic material.
As a result, NdFeB magnets have been used to make automobile components smaller, lighter, and more powerful — helping EV manufacturers extend range, reduce battery requirements, and decrease the copper composition of motors.
Permanent magnet design
NdFeB magnets are based on the crystal structure of the compound Nd2Fe14B. The original design only used Neodymium (symbol Nd) in an alloy of approximately 30% Nd, 1% Boron (B), and 69% Iron (Fe) by weight, resulting in the NdFeB nomenclature.
Modern permanent magnets use varying compositions of Neodymium, Praseodymium (Pr), Dysprosium (Dy), and Terbium (Tb) to further improve the properties of the magnet.
Dy and Tb were the most critical inclusions in modern magnet compositions, as their use renders the permanent magnet strength more durable, especially at higher temperatures. In contrast to their benefits, Dy and Tb are the most costly elements used in modern permanent magnets. As such, materials engineering advancements have carefully balanced a reduction of their concentrations in the magnet alloys while maintaining their magnetic property benefits.
Rare earth magnets, including neodymium magnets, are essential in the traction electric motors of EVs. Their strong magnetic fields deliver high performance and efficiency, critcal for extending the driving range and reducing battery load.
Magnet ratings, such as “N35,” indicate magnetic properties and temperature resistance but do not specify the magnet composition. With modern manufacturing methods designed to reduce the amount of expensive rare earths, the same magnet performance and rating can be achieved as with higher loadings in the past. In short, magnet ratings do not specify composition; they specify performance.
The supply chain
As with most mineral resources, the primary supply chain for rare earths begins at a mine. A mine produces a mixed rare-earth concentrate containing up to 17 rare-earth elements.
This mixed concentrate is sent to an offsite processing facility where, through an arduous process, separated rare earth oxides are produced. Of these 17 elements, the four magnet elements (Nd, Pr, Dy, and Tb) are the most valuable and main economic drivers for rare-earth mining.
Following this, the separated oxides are turned into metals and then NdFeB alloy. Magnet manufacturers will perform a final step of shaping the metal alloy into the size and shape required by an application. Typically, the magnetization occurs at the manufacturer, but can also occur after the magnet is inserted into the final application, such as an EV motor.
In many cases, each of these steps — separation, metallization, alloy making, and magnet manufacturing — is performed by separate companies, although vertically integrated producers do exist.
In the ’80s, California’s Mountain Pass produced the highest amount of rare earths in the world, and the US dominated magnet manufacturing. However, Mountain Pass was eventually forced to shut down due to environmental concerns.
Since then, China’s rare earth deposits have become the primary source of rare earth elements globally. Exploiting these deposits, the Chinese industry developed the processing expertise to extract rare earth elements from ore.
Currently, China controls much of the world’s supply chain, including 60% of rare earth mining, 90% of separation and metallization, and 92% of magnet manufacturing.
Learn more about the recovering and recycling rare earth elements from components in this video.
Risks to the supply chain
With the growing efforts to electrify our world, the demand for these critical rare-earth elements has increased faster than new raw materials are mined.
Adamas Intelligence projects a staggering four-fold increase in demand for magnet rare earth oxides, from 60 kt per year in 2020 to 250 kt per year in 2035. Several new mining projects have been proposed, but there are challenges in opening greenfield mines in time to meet demands.
Additionally, many rare-earth oxide users, such as automobile OEMs, are concerned about supply chain concentration. Global shipping reliability, ESG impact, and geopolitical risk have companies reevaluating near-shoring their supply chains throughout the industry. This is also true for national governments that want to isolate their industry and military from the same supply chain risks.
Increasing circularity
In response to these supply chain risks, the EU and US have strengthened their domestic supply chains for rare earth permanent magnets. The EU has introduced the Critical Raw Materials Act to increase the diversity of supply and circularity for the rare earth elements required for permanent magnets.
The US has begun funding projects associated with rare earth mining and magnet production through the Inflation Reduction Act and the Department of Defense’s Defense Production Act (DPA) Title III program to accelerate the development of a domestic supply chain. One example is the DPA’s funding of VAC’s new US magnet manufacturing facility, which will provide magnets to General Motors, among others.
The recycling of rare-earth permanent magnets is also increasing to address critical supply chain risks. Currently, rare earth permanent magnets are only recycled at around a 1% rate from end-of-life (EOL) devices. This is because magnets stick to steel during the recycling process and follow materials to a steel refinery, where they’re often lost to slag.
New companies are developing ways to recover and refine EOL rare earth permanent magnets from waste to introduce a domestic and recycled supply into the EU and North American markets and alleviate supply chain risks.
Conclusion
Rare-earth magnets are ubiquitous in modern technology, from automotive drive motors to various electric motors throughout all vehicles (including for electronic power steering, pumps, window motors, lift gates, etc.).
These magnets are essential to the energy transition and continued growth of the EV market. Recycling of rare earth permanent magnets can ensure better safety and sustainability.
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