Critical Rare Earths

Mobility would be at a standstill without electric motors and their powerful permanent magnets. These owe their useful magnetic properties to the chemical elements neodymium and dysprosium, which belong to the group of rare earths. Sometimes called critical raw materials, nobody is sure whether the supply of rare earths will hold out in the medium and long term. But ensuring that these raw materials remain available on the world market is far from easy, and prices have been rising steadily for years. One of the factors affecting the expansion of emerging technologies is having these prized resources available in sufficient quantities. This is why Fraunhofer researchers in the »critical rare earths« lighthouse project are working on technologies to process rare earths more efficiently, reuse them or to find suitable substitutes.

Cell phones, laptops, electric motors and wind turbines all have one thing in common: manufacturing them is impossible without the use of rare earths. Electric-vehicle motors and wind-turbine generators in particular require powerful permanent magnets that contain rare earths such as neodymium and dysprosium. What makes these elements so sought after are the outstanding, hard-magnetic properties of the intermetallic bonds they can form with ferromagnetic elements such as iron or cobalt.

The historical label »rare earths« for chemical lanthanide elements is not entirely accurate because, in the cases of what are known as industrial raw materials, we are really dealing with metallic alloys or oxidic compounds made up of these elements. The word »rare« refers to the fact that they are found only in low concentrations amid commonly found minerals and can be obtained only at great effort. Taking into account the advance of green technologies expected over the coming years, it is already clear that a supply of rare earths will be crucial to industry in the medium and long term. This will mainly affect the automotive industry as well as the production of renewable energy, and will in turn threaten the expansion of emerging technologies. With around 48 percent of global reserves and around 85 percent output share at present, China dominates the global market. As an aspiring high-tech country, China has a significant self-interest in strategic metals, which is why it restricts exports to control availability. A consortium made up of seven Fraunhofer Institutes launched the Fraunhofer lighthouse project »critical rare earths« to help ensure a resource-efficient industrial supply of high-performance materials for permanent magnets.

Project Goal: To Halve the Specific, Primary Demand for Heavy Rare Earths

In the lighthouse project, the research team intends to demonstrate how to cut neodymium and dysprosium demand for permanent magnets in half by 2017. This presents the challenges of finding substitute materials, designing more efficient manufacturing technologies, and developing new ways of reusing or recycling electric motors. To demonstrate possible solutions, the researchers will produce two electric motors from magnetic materials that contain lower amounts of neodymium and dysprosium. First up will be a simple, small electric drive, followed later by a complex traction motor. This will be the first time the entire process chain has been modeled – from a theoretical forecast of new magnetic materials down to a functional electric motor. The sheer range of expertise the project team has at its disposal in achieving its goal is unique in Germany. The lighthouse project is divided into the following subprojects:
 

The Search for Substitute Materials

In the Materials Substitution subproject, the research team is collaborating with materials scientists to find new materials that exhibit good magnetic characteristics comparable to those found in hard magnets made from rare earths. Here the scientists use a balance of theoretical modeling and simulation methods, and experimental melt metallurgy techniques. By carrying out systematic computational high-throughput screening and data mining, they can numerically evaluate a wide range of material combinations while at the same time analyzing their hard-magnetic properties. Similar strategies have already been successfully implemented to find new materials for batteries.
 

More Efficient Permanent Magnet Production

A standard technique used in manufacturing high-performance magnets is sintering. A powder mix of the chemical elements neodymium, dysprosium, iron and boron in their magnetic-metallic phase is pressed into a mold before being subjected to high temperatures and pressure to produce the workpiece. Additional processing steps are required to achieve the desired shape. Since sintering is an inefficient way of processing the raw material, the researchers are working up alternative technologies. Their goal here is to produce magnets with the required shape and size in a single manufacturing stage – removing the need for extensive post-processing and saving both material and money.
 

Optimizing Electric Drives

Small electric drives – such as those used for engine cooling or electric power-assisted steering – are designed according to specifications of size and weight related to performance characteristics of operating life, switching frequency, rotational speed, and torque. By taking a constructive approach to small-motor design that allows for future technical requirements, it is also possible to optimize magnet design and pave the way for reducing the amount of dysprosium required. Simply improving cooling systems allows the operating temperature of electric motors to be lowered to the point where they would require up to 21 percent less dysprosium.
 

Reusing and Recycling Raw Materials and Components

In the Design for Recycling subproject, the researchers are exploring the potential for recycling the components and materials that go into electric motors. As there are currently no suitable concepts for returning and reprocessing used electric motors, this is another area where designs are needed that anticipate how motors are to be reused. In the future, electric motors should be designed in such a way that, when the product’s operating life is over, individual components can be easily removed and the raw materials recovered.

Calculating Market Opportunities and Environmental Impact

China’s dominant position as primary producer of rare earths, coupled with increasing demand, means that there is a high risk of neodymium and dysprosium shortages; the lack of market transparency makes it difficult to calculate the risks. Using a dynamic market model, the researchers can evaluate various parameters in order to better estimate technologies developed in the project and their suitability for market application. But calculating the risks rare earth production poses to people and the environment is even less straightforward. Since mining releases toxic and radioactive substances, one of the key tasks facing the researchers is to evaluate how their project can help relieve the environmental burden. The lighthouse project’s findings are to provide support to industry members and politicians in making strategic decisions.