Production of electric motors for electric vehicles, electric generators for wind turbines, and hard disk drives (HDDs) is highly dependent on the availability of rare earth elements (REE) such as Neodymium, Dysprosium, and Praseodymium to produce permanent magnets (which are also called Neodymium magnets). The adoption of permanent magnets is rapidly increasing in various products owing to their phenomenal properties. For example, in the Automotive Market, the Electric motors have permanent magnets, such as neodymium magnets, and in the energy sector, there is a preference for permanent magnets over electromagnets for wind turbines, owing to added benefits such as enhanced efficiency and less installation cost, due to reduced weight of electricity-generating components. This is a positive sign for the segment to flourish in the coming years. Although the prices of these REE are high, currently only about 1% of End-of-Life Neodymium magnets are recycled.
Neodymium magnets are rarely recycled due to difficulties in the separation of REE from the other elements in the magnetic composite: Iron and Boron. While several methods were developed for such separation, all of them consume a large amount of energy and end up with low yield. Therefore, there is an unmet need for an efficient method to recycle REE.
The group of Prof. Lubomirsky developed a rapid and economical process for recycling rare earth metals from end-of-life rare-earth/iron/boron alloy permanent magnets using a chlorine gas treatment.
The key for separation of the REE in permanent magnets (Neodymium, Dysprosium and Praseodymium) from Iron and Boron is the boiling point of their chlorides. While the boiling point of NdCl3, DyCl3 and PrCl3 is more than 1800K, BCl3 is gas at room temperature and FeCl3 boils in 588K. In the extraction method chlorine gas is flowing through pieces of end-of -life magnets in 673K. The chlorine reacts with the magnet to produce the corresponding chlorides, were only the REE chlorides remain in the crucible as a clinker (figure 1)[i]. FeCl3 is collected in a sublimate collector and BCl3 is hydrolyzed to Boric acid when bubbled through water. The REE chlorides can be reduced later to elemental metals by electrolysis or by reaction with Li.
[i] Kaplan, V., Wachtel, E., Gartsman, K. et al. Using Chlorine Gas to Recover Rare Earth Metals from End-of-Life Permanent Magnets. JOM (2021). https://doi.org/10.1007/s11837-021-04592-3
- Recovering rare earth elements (REE) from used magnets.
- High selectivity extraction.
- High yield of conversion- more than 95% for all REE.
- Low temperature process (673K).
- Does not require any special preparation of the magnets
The group developed a laboratory-scale process for recycling rare earth metals from end-of-life rare-earth/iron/boron alloy permanent magnets and demonstrated its efficiency and purity. The following step of reduction of the rare earth metal chlorides in the clinker metal is suggested based on the literature.
Producing permanent magnets is highly depended on the availability of REE. This technology enables to extract those elements from end-of-life magnets to create new ones. The new magnets could implement in many industries such as:
Electric Vehicles Industry: Neodymium magnets are a crucial part of electric engines and they can reduce the energy consumption of electric motor by half. This made the electric vehicles industry a heavy consumer for REE, for example, each Toyota Prius contain about 1 Kg of Neodymium. Recycling those metals from used motors could reduce the costs of producing new ones.
Electricity Industry: Except for photovoltaic cells, all kinds of electricity producers (from wind turbines to nuclear power plants) are based on an electrical generator which contains a huge magnet. Extraction of REE from old generators could lower the costs of replacing it with more efficient new ones.
Recycling Industry: While new SSD containing computers are continuously sold, old HDD containing computers are thrown away. Each HDD contain several grams of neodymium which could be recycled.