Electronic waste is mined for rare earth elements

phys.org | 8/10/2015 | Staff
maye (Posted by) Level 3
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Rare earth elements are the "secret sauce" of numerous advanced materials for energy, transportation, defense and communications applications. Their largest use for clean energy is in permanent magnets, which retain magnetic properties even in the absence of an inducing field or current.

Now, U.S. Department of Energy researchers have invented a process to extract rare earth elements from the scrapped magnets of used hard drives and other sources. They have patented and scaled up the process in lab demonstrations and are working with ORNL's licensee Momentum Technologies of Dallas to scale the process further to produce commercial batches of rare earth oxides.

Process - Materials - Co-inventor - Ramesh - Bhave

"We have developed an energy-efficient, cost-effective, environmentally friendly process to recover high-value critical materials," said co-inventor Ramesh Bhave of DOE's Oak Ridge National Laboratory, who leads the membrane technologies team in ORNL's Chemical Sciences Division. "It's an improvement over traditional processes, which require facilities with a large footprint, high capital and operating costs and a large amount of waste generated."

Permanent magnets help computer hard drives read and write data, drive motors that move hybrid and electric cars, couple wind turbines with generators to make electricity, and assist smartphones to translate electrical signals into sound.

Process - Magnets - Acid - Solution - Module

Through the patented process, magnets are dissolved in nitric acid, and the solution is continuously fed through a module supporting polymer membranes. The membranes contain porous hollow fibers with an extractant that serves as a chemical "traffic cop" of sorts; it creates a selective barrier and lets only rare earth elements pass through. The rare-earth-rich solution collected on the other side is further processed to yield rare earth oxides at purities exceeding 99.5%.

That's remarkable considering that typically, 70% of a permanent magnet is iron, which is not a rare earth element. "We are essentially able to eliminate iron completely and recover only rare earths," Bhave said. Extracting...
(Excerpt) Read more at: phys.org
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