Hidden Gems: Hunting Rare Earth Elements in Georgia Kaolins

Yuanzhi Tang has received a National Science Foundation grant to see if areas along the middle and coastal plains of Georgia that produce a highly sought-after clay are also home to large amounts of rare earth elements (REEs) needed for a wide range of industries, including rapidly evolving clean energy efforts.

Tang is an associate professor in the School of Earth and Atmospheric Sciences at Georgia Tech. She is joined by Crawford Elliott, associate professor  at Georgia State University, on their proposal, “The occurrences of the rare earth elements in highly weathered sedimentary rocks, Georgia kaolins,” funded by the NSF Division of Earth Sciences. 

All about REEs

REEs such as cerium, terbium, neodymium, and yttrium, are critical minerals used in many industrial technology components such as semiconductors, permanent magnets, and rechargeable batteries (smart phones, computers), phosphors (flat screen TVs, light-emitting diodes), and catalysts (fuel combustion, auto emissions controls, water purification). They impact a wide range of industries such as health care, transportation, power generation (including wind turbines), petroleum refining, and consumer electronics. 

“With the increasing global demand for green and sustainable technologies, REE demand is projected to increase rapidly in the U.S. and globally,” Tang says. “Yet currently the domestic REE production is very low, and the U.S. relies heavily on imports. The combination of growing demand and high dependence on international supplies has prompted the U.S. to explore new resources and develop environmentally friendly extraction and processing technologies.”  

Georgia geology

Kaolin is a white, aluminosilicate clay mineral used in making paper, plastics, rubber, paints, and many other products. More than $1 billion worth of kaolin is mined from Georgia’s kaolin deposits every year, more than any other state.

Tang and Elliott say considerable amounts of the REEs have been found in the waste residues generated from Georgia kaolin mining. 

“These occurrences have high REE contents and might add significantly to domestic resources,” Tang says. “By understanding the geological and geochemical processes controlling the occurrence and distribution of REEs in these weathered environments, we might be able to provide fundamental information for the identification of REE resources, and the design of efficient and green extraction technologies.”

“The new work with Dr. Tang has the potential to advance our fundamental understanding of the occurrences, mineralogical speciation, and distribution of the REEs in bauxite and kaolin ore,” Elliott says. “I am thrilled to be working with Dr. Tang on this project.”

Laterite thinking

The Department of Energy notes the 17 rare earth elements are found in highly weathered environments, such as the laterites, a type of soil and rock located in eastern and southeastern China, which currently comprises around 80 percent of the world’s REE reserves. To promote domestic production of REEs, the NSF sought proposals to explore natural unconventional element resources located in highly weathered sedimentary/regolith (loose rocky material covering bedrock) settings in the U.S. Georgia’s kaolin deposits and mines extend in the state from southwest to northeast, paralleling the state’s ‘fall line’ that separates the Piedmont Plateau from the coastal plains.

With the NSF grant, Tang and Elliott will find out more about the geochemical factors and processes controlling REE mobility, distribution, and fractionation (enrichment of light REE versus heavy REE) in these environments, which can provide the foundation to identify domestic resources, and for the rational design of extraction technologies. 

Community connections

The proposed work will also integrate research with education, combining student training with undergraduate education and research, as well as K-12 and community outreach emphasizing the participation of underrepresented groups in geological sciences. 

The grant relates to Tang’s work at two Georgia Tech interdisciplinary research institutes dedicated to sustainability, energy, and climate: the Strategic Energy Institute and the Brook Byers Institute for Sustainable Systems (BBISS), where she is a co-lead with Hailong Chen, an associate professor in the School of Materials Science and Engineering. Tang and Chen’s BBISS project is “Sustainable Resources for Clean Energy.” Tang also serves as an SEI/BBISS initiative lead on sustainable resources.

“The state of Georgia has already been experiencing rapid and exciting developments in the clean energy industry,” Tang says. “We hope to bridge an important link in this space. We hope to help identify and explore regional critical resources for clean energy development by both understanding the geological/geochemical fundamentals, and developing sustainable extraction technologies.” 

Georgia Tech is also investing in the community outreach and social aspects of energy research, not just in science and engineering, Tang adds. “Collaboration with Georgia State University also gives exciting opportunities for the engagement with underrepresented student groups, especially in geological sciences, which will serve in the long term for workforce development.”