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In a National Energy Technology Laboratory (NETL)-supported project with Virginia Polytechnic Institute and State University (Virginia Tech), researchers developed a safe and efficient processing technology that extracts and concentrates rare earth elements (REE) from coal refuse material. The new process decreases the size and cost of needed systems, opening the door to the future commercialization of technologies that can extract REEs from coal refuse.

Virginia Tech’s experiments focused on several fine coal waste materials sampled from active preparation plants in central and northern Appalachian coal basins. The technologies involved the use of ion flotation, which is a process that leverages simple ion-exchange leaching techniques currently used by the industry. The Virginia Tech team focused on modified leaching lixiviants—a novel liquid material used in hydrometallurgy to selectively extract the desired metal from the ore or mineral—instead of using acids to concentrate and extract REEs.

Findings throughout the project proved that novel leaching lixiviants, which assist in rapid and complete leaching, outperformed industry standards in effectively isolating and concentrating REE-enriched clay materials from coal refuse, often at lower quantities of the novel lixiviant. The project successfully produced a solution containing a final REE concentrate of 15 percent to 18 percent by weight, exceeding the objective of 2 percent REE by weight. 

“The fact that this project exceeded its goals is an encouraging development,” said NETL’s Project Manager Anthony Zinn. “Now that the concept has been demonstrated, Virginia Tech can begin the process of refining it to make it more economical and attractive for investors on a large scale beyond the laboratory setting.”

Zinn explained that the ion flotation demonstrated by Virginia Tech’s researchers offers a technical benefit because it can effectively increase REEs in the leach solutions prior to solvent extraction. Feeding a solvent extraction unit with a higher concentration of REEs would reduce the size and cost of such a system.

“The project also presents environmental benefits because modified leaching lixiviants would be far less hazardous than strong acids that are generally used to extract REEs from solid feedstocks,” Zinn said. “This means that workers would be operating in safer environments and there would be easier storage and disposal options for these materials.”

This project is part of a NETL-funded cooperative agreement intended to develop a domestic supply chain for REEs, which are vital to the manufacturing of personal electronics, energy infrastructure, and defense technologies, among many other high-tech applications.

NETL is a U.S. Department of Energy National Laboratory that produces technological solutions for America’s energy challenges. NETL research is providing breakthroughs and discoveries that support domestic energy initiatives, stimulate a growing economy, and improve the health, safety, and security of all Americans. Highly skilled men and women at NETL’s sites in Albany, Oregon; Anchorage, Alaska; Houston, Texas; Morgantown, West Virginia; and Pittsburgh, Pennsylvania conduct a broad range of research activities that support the Department’s mission to advance the national, economic, and energy security of the United States.