From cell phones to wind turbines and missile defense systems, modern technologies depend on critical minerals like rare earth elements. As demand grows, researchers are exploring more efficient and adaptable methods to recover and reuse these materials.
A new study suggests that magnets make the process more efficient.
Waste from coal power plants, mining operations and oil and gas wells contains trace amounts of rare earth elements , such as dysprosium and lanthanum, which are used in electric vehicles, rechargeable batteries and defense technologies.
Current industrial methods for extracting these elements from domestic feedstocks depend on complex processes that are energy-, cost- and time-consuming, and produce significant chemical waste.
University of Mississippi doctoral student Ivani Jayalath collaborated with a team of researchers in the Non-Equilibrium Transport Driven Separations initiative at Pacific Northwest National Laboratory to develop new methods for recovering critical minerals. Their results, published in Separation and Purification Technology , show that magnets streamline this process while reducing energy and chemical consumption as well as waste generation.
"There is an urgent demand for rare earth elements due to recent technological advancements and supply chain disruptions," said Giovanna Ricchiuti, a postdoctoral researcher at the national laboratory and the first author of the study. "This presents a challenge as most of these elements have very similar chemical and physical properties. Because of their similarities, it is very difficult to find an efficient way to separate them.
"We exploit small differences in magnetic susceptibility, or the magnetic moment of these ions. Based on these small differences, we use magnetic field gradients to drive selective transport and separation."
Despite the similarities between the elements, they respond differently to magnetic field gradients, allowing researchers to use a simple permanent magnet to separate targeted elements from other components in liquid feedstocks, said Jayalath, an Ole Miss doctoral student in chemistry . Unlike traditional methods, the process is also faster and produces less chemical waste, she said.
"Traditional separation methods use large amounts of organic solvents," Jayalath said. "This increases waste disposal costs and can cause harmful environmental effects.
"Using magnets offers a simple and potentially more sustainable way to assist separation processes. In our study, magnetic fields helped drive selective ion transport and concentration from solution."
The national laboratory developed an imaging system that uses lasers to detect the movement of ions in real time, Ricchiuti said. This system allows the researchers to observe enrichment zones – areas where ions are concentrated in response to the magnet – and depletion zones, or areas where ions are repelled from the magnet.
"The magnetic field creates dynamic 'ion concentration waves' and enrichment or depletion zones due to the interplay of magnetic drift, diffusion and self-generated electric fields," she said.
When the researchers combined a precipitating agent with a magnetic field, they observed enhanced crystallization of the dissolved rare earth elements, making them easier to extract.
While this is an initial study, the team said implementing a magnet-based approach is a potentially promising step toward improving current extraction processes.
"The world is looking for robust and sustainable energy and supply chains for critical minerals," Jayalath said. "We need these elements for electric cars, batteries and other technologies. So, they are essential for the future.
"That is why we need to focus on how to extract and recycle these elements efficiently."
