Researchers file for Patent to Recover Rare Earth Elements from Coal and Coal Byproducts
New technology addresses White House Executive Order declaring a national emergency on the supply of critical rare earth elements
Virginia Tech Intellectual Properties (VTIP) recently filed a patent application for a new technology developed by Roe-Hoan Yoon, University Distinguished Professor and Director of the Center for Advanced Separations Technologies, and Aaron Noble, mining and minerals engineering associate professor, to extract rare earth elements from coal refuse materials. The application follows the recent announcement of the American Energy Society, which recognized the technology as its Energy Technology of the Year.
According to a 2015 Tetra Tech report, the majority of rare earth elements associated with coal favor partitioning to clay materials, with only a relatively small amount partitioning to organic materials. In the U.S. coal industry, clayey materials are discarded as waste into numerous impoundments along with the coal fines that are difficult to recover. The concentrations of rare earth elements associated with the clayey materials are low; therefore, the cost of extracting them must be substantially lower than those for conventional rare earth resources, such as those in Mountain Pass, CA, and Bayan Obo, Inner Mongolia.
The initial separations step of the new technology involves decarbonization, by which salable coal is recovered from fine coal refuse using the hydrophobic-hydrophilic separation (HHS) process, developed earlier at Virginia Tech and commercialized by the Minerals Refining Company, Richmond, VA. In the next step, the rare earth elements are extracted from clayey and other materials left over from the decarbonization step. The second step is similar to the ion-exchange leaching process used in South China to extract rare earth elements at low cost from the weathered crust of granite – the best-known igneous rock. The U.S. Geological Survey reported the presence of similar, non-conventional rare earth resources in Virginia’s Appalachian Mountains near Stewartsville, Striped Rock, Amissville, and Battle Mountain.
“Extracting rare earth elements from fine coal refuse has merits and could lead to significant societal benefits; however, the process can be quite difficult and costly depending on the geochemical environment under which the non-conventional resources have been formed during the geological time scale,” said Noble. “The innovative approach we have developed addresses these difficulties,” he added.
The patent application addresses a September 2020 White House Executive Order declaring a national emergency on the supply of rare earth elements, which are critical to high-tech industries, national security, and renewable energy resources. With little to no domestic production at the moment, the U.S. imports 80% of its rare earth needs from China, leaving its economy and national security vulnerable to possible supply disruptions.
“Having low mining costs while producing salable coal as byproduct helps the economy,” Roe-Hoan Yoon, University Distinguished Professor, added. He credits the success of his research group to team members with diverse expertise in chemistry, separation science, and process engineering. If successful, the production of rare earths from fine coal waste alone can easily meet the domestic needs for the critical materials.
Congressman Morgan Griffith lauded the team’s effort and described how this new separation technology can benefit citizens in the coal regions and throughout the Commonwealth. “I am excited that the research of Dr. Yoon, Dr. Noble, and the Center for Advanced Separation Technologies will take this significant step forward. Rare earth elements are vital to our national security and economic future. Innovation in separating rare earth elements from coal refuse materials will help our country secure domestic supplies of these elements and create economic opportunity where they can be found, including in the coalfields of Southwest Virginia.”
Dr. Joel Cornfield, a managing partner of Grimstone Mining, LLC, who has signed an agreement with VTIP stated, “We are delighted at the opportunity to enter into an agreement to play a role in developing this exciting and important technology. Grimstone firmly believes that this new process will provide numerous long-term benefits including the creation of well-paying jobs and the removal of previously discarded coal GOB through a relatively environmentally friendly means, all while providing materials essential for our national security.”
“Rare earth elements are not rare; what is rare are the efficient separation technologies for extracting them,” said Yoon. The development of the new and efficient separation method by its four co-inventors at Virginia Tech required significant research funding from the Rare Earth Elements and Critical Minerals (REECM) Program of the National Energy Technology Laboratory (NETL), U.S., Department of Energy.