Extracting Rare Earth Metals from Coal Waste
Rare earth elements (REE), often referred to as “rare earth metals,” are crucial for their use, along with their oxides, in various modern devices. These include the use of REEs for batteries in computers, cell phones, and electric vehicles, and the use of rare-earth oxides for digital displays, monitors, and televisions. REEs are also used as catalysts, phosphors, and polishing compounds.
In response to increasing demands for REEs, the US is seeking alternative production of REEs. The Bipartisan Infrastructure Law, passed on November 15, 2021, gave the US Department of Energy (DOE) $140 million for fiscal year 2022 to establish a rare earth elements demonstration facility. The purpose of the facility is as follows, with extraction from coal waste:
“(A) provide environmental benefits through use of feedstock derived from acid mine drainage, mine waste, or other deleterious material;
(B) separate mixed rare earth oxides into pure oxides of each rare earth element;
(C) refine rare earth oxides into rare earth metals; and
(D) provide for separation of rare earth oxides and refining into rare earth metals at a single site.”
On February 9, 2022, a study conducted by James Tour and his team from Rice University in Houston, Texas, which included DOE funding, was published in Science Advances. Tour’s team reported the use of superfast flash Joule heating (FJH) on coal waste to improve REE extractability.
The DOE then released a Request for Information (RFI) on February 14, 2022 to solicit feedback from relevant stakeholders regarding the proposed rare earth elements demonstration facility, including demonstration facility features, supply chain considerations, research and development needs, and more.
Improvements are still needed in the extraction of REEs from coal waste. However, there is promise in new technologies, such as in the study above, to make the extraction of REEs more practical, especially given the amount of coal waste that already exists.