Review
Chemistry, Inorganic & Nuclear
Daniele Paderni, Luca Giorgi, Vieri Fusi, Mauro Formica, Gianluca Ambrosi, Mauro Micheloni
Summary: Rare earth elements (REEs) are a group of elements playing critical roles in modern applications, with scientists showing strong interests in their new applications. However, the development of chemical sensors suitable for selective sensing of REE ions remains a challenging task due to their complicated coordination properties.
COORDINATION CHEMISTRY REVIEWS
(2021)
Article
Environmental Sciences
Xuexian Li, Wenlang Qiao, Deng Chen, Pan Wu, Yixi Xie, Xue Chen
Summary: Anomalous concentrations of rare earth elements (REEs) were found in the acid mine drainage (AMD) from a coal-mine area in northern Guizhou, China. The claystone from the floor of the coal seam was identified as a potential secondary source of extractable REEs, which were mainly adsorbed by clay minerals. Further studies will focus on the extraction model and economic benefits of REEs from the claystone samples.
SCIENCE OF THE TOTAL ENVIRONMENT
(2023)
Review
Engineering, Chemical
Orevaoghene Eterigho-Ikelegbe, Hamza Harrar, Samson Bada
Summary: This article discusses the current status and potential strategies for recovering REEs from coal and coal discard, including the feasibility of physical beneficiation and hydrometallurgical leaching. It highlights the abundance of REEs in coal but also the need to address processing costs and knowledge gaps to advance REEs recovery from these sources.
MINERALS ENGINEERING
(2021)
Article
Energy & Fuels
Juanjuan Ma, Shuyan Li, Jinxi Wang, Shuting Jiang, Balaji Panchal, Yuzhuang Sun
Summary: This study optimized the culture conditions and bioleaching process of Aspergillus niger for the extraction of rare earth elements (REEs) from coal fly ash (CFA). It was found that organic nitrogen sources influenced the morphology and acid production capacity of A. niger, with oxalic acid being the main acid secreted (4.05 mg/L). The initial pH value was identified as the most influential factor affecting the bioleaching process, and by optimizing it, a leaching rate of 30.91% for total REEs in CFA was achieved. The main mechanism of REEs bioleaching by A. niger from CFA was speculated to be proton exchange and organic ligand complexation.
Article
Environmental Sciences
Mathieu Desrosiers, Guillaume Pelletier, Denis Dieme, Jonathan Cote, Malek Jomaa, Andy Nong, Michele Bouchard
Summary: Toxicokinetic models are developed for four rare earth elements to establish biomonitoring equivalents (BE) as biological guidance values, based on experimental kinetic data showing disappearance from blood, accumulation in liver, and excretion mainly through feces. The model with 19 compartments fits well with experimental data and can be used for other REEs modeling. BEs of Pr and Nd were derived from provisional RfD, allowing for rapid screening and risk assessments in different populations.
ENVIRONMENT INTERNATIONAL
(2021)
Review
Thermodynamics
Biao Fu, James C. Hower, Wencai Zhang, Guangqian Luo, Hongyun Hu, Hong Yao
Summary: This review critically summarizes recent progress in the study of REY in coal ash, evaluating the content, speciation, and extraction potentials of REY. It discusses the different forms, distribution behavior, and transformation mechanisms of REY in coal ash, and proposes possible retention mechanisms of REY by aluminosilicate glass at boiler temperature. The modification of REY speciation in fly ash by reactions with flue gas components and current extraction techniques for REY recovery from coal combustion ash are also highlighted.
PROGRESS IN ENERGY AND COMBUSTION SCIENCE
(2022)
Article
Energy & Fuels
James C. Hower, Cortland F. Eble, Shelley D. Hopps, Tonya D. Morgan
Summary: The chemistry of rare earth elements in Pond Creek coal in Pike County, Kentucky was examined, and it was found that their concentration and distribution varied significantly between lithotypes, possibly due to hydrothermal enrichment and geological movements.
INTERNATIONAL JOURNAL OF COAL GEOLOGY
(2022)
Article
Energy & Fuels
James C. Hower, John G. Groppo, Cortland F. Eble, Shelley D. Hopps, Tonya D. Morgan
Summary: The Springfield coal in the Western Kentucky coalfield, a part of the Illinois Basin, ranges from high volatile A bituminous to high volatile C bituminous. The chlorine content closely follows coal rank, with highest concentration in high volatile A bituminous coals. V and Cr concentrations are high in top benches, particularly in higher rank sites. Zn and other elements show inconsistent enrichment patterns. Zr + Nb content is highest in high volatile C bituminous Spottsville quadrangle coals.
INTERNATIONAL JOURNAL OF COAL GEOLOGY
(2023)
Article
Nanoscience & Nanotechnology
Alexander T. Brown, Kenneth J. Balkus
Summary: There is a need for the development of new solid-phase adsorbents for element extraction from coal ash. High surface area carbon adsorbents are effective in adsorbing rare earth elements, and MFC-O has shown exceptional extraction capabilities for rare earth elements, thorium, and uranium. The binding properties of MFC-O make it an attractive material for selective extraction of rare earth elements from coal ash.
ACS APPLIED MATERIALS & INTERFACES
(2021)
Article
Energy & Fuels
James C. Hower, John G. Groppo, Heileen Hsu-Kim, Ross K. Taggart
Summary: The distribution of Rare Earth elements (REE) in coal-derived fly ashes varies depending on the coal source and basins. Different coal types exhibit variations in REE concentration and distribution in fly ashes. The signature of REE in fly ashes can be indicative of their behavior in extraction processes, but the actual distribution may differ between fly ashes from different basins.
Article
Environmental Sciences
Xuexian Li, Ruixue Zhang, Qingguang Li, Pan Wu, Huijun Ye
Summary: The study found that CMD in Guizhou coal mine areas contains varying concentrations of REY, with some CMD being enriched in critical-REY. The geochemical compositions of CMD and geological conditions are significantly correlated with the behaviors of REY in CMD, with elevated concentrations of dissolved REY found in acidic CMD.
SCIENCE OF THE TOTAL ENVIRONMENT
(2021)
Article
Engineering, Chemical
Shan Wu, Chao Bie, Hao Su, Yun Gao, Xiaoqi Sun
Summary: Two novel salicylic acid derivatives, OOBA and EHOBA, were synthesized for the extraction and separation of Y from ion adsorbed rare earth ores. The study found that OOBA exhibits similar extraction behavior to LREEs and has better selectivities for Y and other HREEs compared to common carboxylic acids. The extraction mechanism of OOBA was determined to be cation exchange. Furthermore, OOBA demonstrated advantages such as low stripping acid concentration, good cycle stability, and minimal loss in the extraction process. A simulated fractional extraction process was developed to separate Y from the Y-enriched HREEs feed liquid, resulting in a Y product with high purity and yield.
MINERALS ENGINEERING
(2022)
Article
Chemistry, Applied
M. Rucki, K. Kejlova, A. Vlkova, D. Jirova, M. Dvorakova, L. Svobodova, H. Kandarova, S. Letasiova, H. Kolarova, M. Mannerstrom, T. Heinonen
Summary: The study aimed to investigate the toxicological profile of rare earth elements salts (REEs) through a series of experiments evaluating cytotoxicity, environmental toxicity, skin irritation and corrosion potential, mutagenicity, endocrine disruption, and skin sensitization. The results showed that the tested REEs have no potential for mutagenicity or skin sensitization, but exhibit acute and chronic toxic effects on the aquatic environment.
JOURNAL OF RARE EARTHS
(2021)
Review
Polymer Science
Gabriel Salfate, Julio Sanchez
Summary: The demand for rare earth elements (REEs) has been increased by contemporary industrial processes and the application of new technologies. However, the increased mining of REEs has led to a supply crisis. Researchers have recently started considering the viability of recovering REEs from secondary sources such as mining wastewaters and acid mine drainage. In order to find more sustainable processes, the performance of various adsorption/ion exchange materials in capturing REEs from water sources is being evaluated.
Article
Energy & Fuels
Panpan Xie, Jingjing Liu, Biao Fu, Thomas Newmaster, James C. Hower
Summary: This article investigates the tailings material from the beneficiation of high volatile C bituminous coal and finds that although the concentration of critical elements like rare earths is low, the material has the potential to be an important resource.