Leaching Behavior of Rare Earth Elements in Fort Union Lignite Coals of North America

Journal Article · Sun Apr 15 00:00:00 EDT 2018 · International Journal of Coal Geology

DOI:https://doi.org/10.1016/j.coal.2018.03.010· OSTI ID:1512701

Laudal, Daniel A. ^[1]; Benson, Steven A. ^[1]; Addleman, Raymond S.  ^[2]; Palo, Daniel ^[3]

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1. University of North Dakota
2. BATTELLE (PACIFIC NW LAB)
3. Barr Engineering

Rare earth elements are crucial materials in an incredible array of consumer goods, energy system components and military defense applications. However, the global production and entire value chain for rare earth elements is dominated by China, with the U.S. currently 100% import reliant for these critical materials. Traditional mineral ores including those previously mined in the U.S., however, have several challenges. Chief among these is that the content of the most critical and valuable of the rare earths are deficient, making mining uneconomical. Further, the supply of these most critical rare earths is nearly 100% produced in China from a single resource that is only projected to last another 10 to 20 years. The U.S. currently considers the rare earths market an issue of national security. It is imperative that alternative domestic sources of rare earths be identified and methods developed to produce them. Recently, coal and coal byproducts have been identified as one of these promising alternative resources. This paper details the results of a study on characterization of North Dakota lignite and lignite-related feedstocks as an assessment of their feasibility for rare earth element recovery. The abundance, distribution and modes of occurrence of the rare earth elements in the samples collected were determined in this initial study to inform the selection of appropriate extraction and concentration methods to recover the rare earth elements. Materials investigated include the lignite coals, clay-rich sediments associated with the coal seams, and materials associated with a lignite beneficiation system and power plant. The results show that high rare earth element levels exist both in lignite coals and associated sediments. The form of the rare earth elements in the clay materials is primarily as ultra-fine mineral grains. In the lignite coals, approximately 80-95% of the rare earths content is organically associated, primarily as coordination complexes.

• Research Organization: Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
• Sponsoring Organization: USDOE
• DOE Contract Number: AC05-76RL01830
• OSTI ID: 1512701
• Report Number(s): PNNL-SA-133066
• Journal Information: International Journal of Coal Geology, Vol. 191
• Country of Publication: United States
• Language: English