Extraction of Rare Earth Elements from Idaho-Sourced Soil Through Phytomining: A Case Study in Central Idaho, USA

Kathryn Richardson, Amin Mirkouei (), Kasia Duellman, Anthony Aylward, David Zirker, Eliezer Schwarz and Ying Sun
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Kathryn Richardson: Environmental Science Program, University of Idaho, Idaho Falls, ID 83402, USA
Amin Mirkouei: Environmental Science Program, University of Idaho, Idaho Falls, ID 83402, USA
Kasia Duellman: Department of Entomology, Plant Pathology and Nematology, University of Idaho, Idaho Falls, ID 83402, USA
Anthony Aylward: Rare Flora Inc., UCR Life Science Incubator, Multidisciplinary Research Building (MRB), 900 University Ave, Riverside, CA 92501, USA
David Zirker: Department of Nuclear Engineering and Industrial Management, University of Idaho, Idaho Falls, ID 83402, USA
Eliezer Schwarz: Department of Biological Sciences, Idaho State University, Idaho Falls, ID 83404, USA
Ying Sun: Rare Flora Inc., UCR Life Science Incubator, Multidisciplinary Research Building (MRB), 900 University Ave, Riverside, CA 92501, USA

Sustainability, 2025, vol. 17, issue 11, 1-16

Abstract: Environmentally friendly and low-emission extraction methods are needed to meet worldwide rare earth element (REE) demand. Within a greenhouse setting, this study aims to investigate the REE hyperaccumulation ability of four plant species (e.g., Phalaris arundinacea , Solanum nigrum , Phytolacca americana , and Brassica juncea ) and the impact of amending REE-rich soil with biochar or fertilizer and watering with citric acid solution. Harvested samples were pyrolyzed, and the resulting bio-ores were acid-digested and underwent elemental analysis to determine REE content. Amending soil with fertilizer and biochar increased bio-ore production, while plant species explained the most variation in bioaccumulation factor. The results indicate that Phalaris arundinacea achieved the highest average REE concentration of 27,940 µg/g for the targeted REEs (comprising cerium, lanthanum, neodymium, praseodymium, and yttrium) and 37,844 µg/g for total REEs. It is also found that soil amendment and plant species are critical parameters in the design and implementation of Idaho-based REE phytomining operations. The life cycle assessment study estimated that the electricity demand of the greenhouse contributed the most to GHG emissions during the greenhouse study. Within the field study, electricity demand of the pyrolysis reactor was determined to be the largest producer of GHGs. The techno-economic analysis estimated that the total cost of growing P. arundinacea for six weeks on a one-acre field area is USD 6213, including 39%, 22%, 21%, and 18% of that cost derived from cultivation, biomass processing, soil treatment with fertilizer, and pyrolysis, respectively. It is concluded that the proposed low-emission extraction pathway, which combines phytomining, drying, and pyrolysis, is a promising sustainable approach for REE extraction, especially from REE-rich soil sourced in Idaho.

Keywords: rare earth elements; extraction; phytomining; hyperaccumulator plants; bio-ore; Phalaris arundinacea; life cycle assessment; techno-economic analysis (search for similar items in EconPapers)
JEL-codes: O13 Q Q0 Q2 Q3 Q5 Q56 (search for similar items in EconPapers)
Date: 2025
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