From Trash to Treasure: US Researchers Recover Rare Earths from E-Waste

Researchers from the US Department of Energy have invented a process for extracting rare earths from the e-waste of scrapped magnets of used hard drives and other sources, and are working with colleagues at Oak Ridge National Laboratory, to scale up the method and produce commercial batches of rare earth oxides, according to Mining.com.

E-waste is discarded electrical or electronic devices. Used electronics that are destined for refurbishment, reuse, resale, salvage recycling through material recovery, or disposal are also considered e-waste. Informal processing of e-waste in developing countries can lead to adverse human health effects and environmental pollution.

electronic waste is mined for rare earth elements image

To extract rare earth elements, the US scientists dissolve the magnets in nitric acid and continuously injected the solution into them through a module supporting polymer membranes. The membranes contain porous hollow fibers with an extractant that acts as a chemical "traffic cop" of sorts because it creates a selective barrier that allows only rare earth elements to pass through. The rare-earth-rich solution collected on the other side is further treated to yield rare earth oxides at purities exceeding 99.5%.

In general, 70% of permanent magnets are iron, while the iron is not a rare earth element. However, with the new process, it is possible to eliminate Fe components and recover only rare earths. This means that less waste is created when compared to other mechanisms aimed at producing similar results.

Ramesh Bhave, co-inventor of the Oak Ridge National Laboratory, said in a media statement: “We have developed an energy-efficient, cost-effective, environmentally friendly process to recover high-value critical materials,” This is an improvement over traditional processes." which require facilities with a large footprint, high capital and operating costs and a large amount of waste generated.”

researchers of Oak Ridge National Laboratory use Feedstock magnets to recover rare earths image

Besides hard drives, magnets are being recovered from magnetic resonance imaging machines, cell phones, and hybrid cars. Most of the rare earth elements obtained from them are lanthanides, elements with atomic numbers between 57 and 71 in the periodic table. Examples of these are neodymium, praseodymium, and dysprosium.

In the second phase, the US researchers will also explore whether the underlying process for separating rare earths can be developed for separating other in-demand elements from lithium-ion batteries, such as lithium and cobalt, to reduce the waste and save energy cost from the e-waste.

 

 

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