In 2016, a team of Penn State and U.S. Department of Energy researchers discovered a cost-effective and environmentally friendly way to extract rare earth elements (REEs) from coal and coal byproducts. Now, through a $1 million grant from DOE's Office of Fossil Energy, this research may be headed one-step closer to commercialization.
Rare-earth oxides, clockwise from top center: praseodymium, cerium, lanthanum, neodymium, samarium, and gadolinium. Image: Peggy Greb / USDA
Penn State and a consortium of three industry partners, Texas Mineral Resources Corporation (TMRC), Inventure Renewables Inc., and K-Technologies, will use the funding to conduct laboratory testing and prepare a technical design for a pilot plant to profitably produce salable REEs and other critical elements from coal-related materials from an eastern Pennsylvania anthracite coal mine. The goal is to determine the economic feasibility of recovering REEs from domestic coal and coal by-products.
Penn State researchers found
initial success in extracting REEs in 2016 using ion exchange, which involved extracting coal byproducts with a solvent that releases the rare-earth elements bound to them. Through this new grant, the researchers will develop a new extraction technique that combines pressure filtration, which uses external forces to separate solids from fluids, with an environmentally friendly ion-exchange/ion-chromatography process. The resulting REE-enriched liquid can be processed to recover the elements while recycling the liquid for reuse in the system.
"We're interested in using environmentally friendly solvents that will be the best at reacting with these elements and extracting them," said
Sarma Pisupati, professor of energy and mineral engineering at Penn State. "If we reach a ceiling with the method of ion exchange, we will begin to test alternative methods that may be economical and environmentally feasible. We believe this novel approach for extraction will be able to provide the high efficiency and throughput sought by the industry for a technologically feasible and an economically viable extraction method for REEs."
TMRC's focus will be to install a self-contained, modular and portable continuous-ion-exchange/continuous-ion-chromatography pilot plant in Pennsylvania, and to determine the economic viability of producing scandium and other REEs associated with coal waste material from Pennsylvania coal.
"The potential to profitably produce scandium and other rare earth minerals from Pennsylvania coal waste holds great promise," said TMRC Chairman Anthony Marchese. "Creating value profitably from waste is an environmental goal shared by all citizens, especially when considering the strategic nature of the minerals proposed to be produced."
REEs are a group of 17 elements — all metals — found in the Earth's crust. REEs have unique chemical properties making them essential components of technologies ranging from electronics, computer and communication systems, transportation, health care, and national defense. The United States Geological Survey expects worldwide demand for rare earth elements to grow more than 5 percent annually through 2020. The increased demand for REEs has spurred interest in developing cost-effective technologies for domestic REE recovery.
The team of Penn State researchers includes Pisupati;
Mark Klima, associate professor of mineral processing and geo-environmental engineering; and Xiaojing Yang, graduate student in energy and mineral engineering.