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Purdue study highlights lifecycle benefits of neodymium-iron-boron magnet-to-magnet recycling for electric vehicle motors

In August 2017, international metals and minerals research firm Roskill reported that Tesla would use a 3-phase permanent magnet motor in the Model 3 RWD Long Range as the powertrain motor, as opposed to the asynchronous reluctance (induction) motors used in the Model 3 RWD standard and Model X AWD. At that time, Roskill suggested that neodymium (Nd) and praseodymium (Pr)—the two rare earth elements which form the majority of rare earth permanent magnets—would see further price increases as as demand increased and the Chinese dominance of supply restricts availability for many consumers.

Reuters earlier this week reported that with the additional projected demand generated by Tesla’s neodymium switch, the market for the neodymium-iron-boron magnet used in the motors is now worth more than $11.3 billion, with demand for the magnets rising at a compound annual growth rate of 8.5% between 2010 and 2017.

That article quoted Roskill’s David Merriman as saying that global demand of 31,700 tonnes for neodymium last year already outstripped supply by 3,300 tonnes. Merriman expects demand to climb to 34,200 tonnes this year and 38,800 tonnes in 2019, leaving larger deficits.

Into this market turmoil comes a study by Purdue University researchers, with colleagues at Urban Mining Company, detailing the lifecycle benefits of neodymium-iron-boron magnet-to-magnet recycling for electric vehicle motors. Their study is published in the ACS journal Environmental Science & Technology.

REE demand for NdFeB magnets in clean technologies such as electric vehicles is projected to increase dramatically. One strategy to mitigate supply risk is through recycling. Conventional pyro or hydrometallurgical methods are energy or chemically intensive as they separate REEs back to pure oxides. An alternative approach is to bulk-recycle all the materials in an NdFeB magnet without separation. This has been termed ‘magnet-to-magnet recycling’.

Recently, novel technologies have been developed to process end-of-life (EOL) NdFeB magnets into ‘new’ NdFeB magnets that retain or improve magnetic performance relative to starting materials. Magnet-to-magnet recycling has two major advantages: 1) it recovers all the magnet materials and reuses them in new magnets, minimizing waste and resource depletion, and 2) it utilizes mechanical rather than chemical processes, reducing the environmental footprint associated with chemical usage and harmful emissions.

The environmental impacts of NdFeB magnet recycling have not been well studied. … To correct this deficiency, the research described herein provides a comprehensive and reliable LCA on a real, industrial-scale NdFeB magnet-to-magnet recycling process. The material and energy input and output data were obtained from primary measurements, augmented with information from the literature where necessary. With this information, the environmental impacts of NdFeB magnet-to-magnet recycling were assessed and compared with ‘virgin’ production.

—Jin et al.

The study compared the lifecycle impacts of producing 1 kg of NdFeB magnets from virgin materials and 1kg of equivalent magnets from magnet-to-magnet recycling. Both magnets ere suitable for high-temperature applications such as EVs, offers similar performance, and could be used interchangeably.

Global warming potential of each processing step in virgin production and magnet-to-magnet recycling for 1kg of NdFeB magnets. Credit: ACS, Jin et al. Click to enlarge.

Starting feedstock materials for recycling were harvested magnets from EOL hard disk drives (HDDs). New materials such as iron, REEs, and other metals are required for both processes, but the specific material composition and quantities differ.

In recycling, only 0.0005-0.001 kg of new materials are required to produce 1kg of NdFeB magnets, while virgin production requires 1.3-3.0 kg—some of which is lost during sintering & annealing and grinding & slicing.

Process flows for NdFeB magnet virgin production and magnet-to-magnet recycling. Credit: ACS, Jin et al.Click to enlarge.

The baseline assessment found that the recycling route has substantially lower environmental impacts than virgin production in all ten impact categories. The processes that are distinctive from virgin production in terms of LCI (i.e., magnet harvesting, de-coating, and melting for magnet-to-magnet recycling vs. strip casting for virgin production) have significantly lower impacts.

The team found three key processes to be the most impactful:

  1. hydrogen mixing & milling (contributing 13-52% of the total environmental footprint);

  2. sintering & annealing (6-24%); and

  3. electroplating (6- 75%)

Within hydrogen mixing & milling, electricity contributes 99-100% of the total impact. For sintering & annealing, electricity contributes 70-100% of the total impact. For electroplating, the nickel coating material contributes 73-99% of the total impact.

The LCA results confirm that magnet-to-magnet recycling substantially lowers the environmental footprint of NdFeB magnet production, largely due to its minimal use of fresh REEs. By adopting greener electricity sources such as wind and hydroelectric power, the environmental footprint of NdFeB magnet-to-magnet recycling could be further reduced. These results also suggest possible directions for further development of magnet-to-magnet recycling to maximize the environmental benefits of this new technology.

—Jin et al.

Urban Mining Company is a for-profit corporation funded by private investment and the Defense Logistics Agency.


  • Hongyue Jin, Peter Afiuny, Stephen Dove, Gojmir Furlan, Miha Zakotnik, Yuehwern Yih, and John W. Sutherland (2018) “Life Cycle Assessment of Neodymium-Iron-Boron Magnet-to-Magnet Recycling for Electric Vehicle Motors” Environmental Science & Technology doi: 10.1021/acs.est.7b05442


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