Rare earth elements and transition metals can be separated selectively using a technology developed for water treatment.
FREMONT, CA: In nature, rare earth metals tend to occur in low concentrations and can be difficult to separate from each other because they are chemically similar. Wind turbines, electric car motors, and computer hard drives use them. With high melting points and unique structural properties, transition metals are excellent thermal and electrical conductors, essential for producing common alloys such as steel, copper, and lithium-ion batteries.
Unlike traditional methods, which typically use hundreds of degrees Celsius, dimethyl ether-driven methods use significantly less energy and pressure. Approximately five atmospheres of pressure are needed for fractional crystallization to occur at ambient temperatures. Comparatively, an unopened 12-ounce soda can has 3.5 atmospheres of pressure. In addition to saving money, lower energy and pressure requirements reduce operating costs.
Competing technologies also use chemical "reagents" to drive precipitation and other separation processes, which result in additional waste products with financial and environmental consequences. With fractional crystallization based on dimethyl ether, this is not the case.
The team developed the zero-waste solvent-based metal recovery process by incorporating electrochemical rare earth metal recovery processes already in place at INL. An example is E-RECOV, which enables electronic waste to be recovered efficiently through an electrochemical cell. Critical material recovery can also be made more sustainable by reducing energy intensity and waste profile.