Article
Metallurgy & Metallurgical Engineering
Jian-qiang Xue, Jian-xin Liu, De-zhi Huang, Wei-jian Zhou, Chun-ming Liu, Yu-sen Cao, Chuang-hua Cao
Summary: By analyzing the trace elements of coals, host-rocks, and wall-rocks from Bayili Coal Mine in Xinjiang, China, this study aims to trace the sources and evaluate the utilization prospects of REY in the coals. The distribution patterns of REY in the coals are divided into flat-type and heavy REE-enrichment type (H-type), while the host-rocks show middle REE-enrichment type (M-type) and H-type patterns. Almost all coal samples at Bayili Coal Mine are in a promising area on the diagram of percentage of critical elements vs ratio of sum of critical elements to sum of excessive elements, indicating good utilization prospects as by-product.
TRANSACTIONS OF NONFERROUS METALS SOCIETY OF CHINA
(2021)
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
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)
Article
Microbiology
Stephanie Skeba, Morgan Snyder, Chris Maltman
Summary: The field of microbe-metal interactions has gained significant attention. This study identified eight bacterial isolates with siderophore and metallophore activity, mostly from sites impacted by coal mine drainage. These findings suggest that bacteria may play a role in the removal/recovery of critical elements.
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
Geochemistry & Geophysics
Sophia Bauer, Jonathan Yang, Mengling Stuckman, Circe Verba
Summary: Rare earth elements (REEs) and critical minerals (CMs) are increasingly used in various modern industries. Optimizing extraction techniques and understanding the distribution of REEs in different solid fractions can stabilize the unpredictable supply chain. The co-extraction of critical metals during the extraction process is observed. The mobility of major cations and REEs is associated with specific fractions, while non-extractable REEs are likely held in refractory apatitic phases or primary REE-phosphates.
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
Environmental Sciences
Shengfeng Liu, Bai Gao, Keng Xuan, Wenjie Ma, Nan Chen, Meiyu Jia
Summary: Sulfur autotrophic denitrification (SAD) is an efficient method for wastewater denitrification. In this study, a permeable reactive barrier technology with a SAD composite filler was created to treat rare earth mine groundwater. The results showed that the technology had a high nitrate removal efficiency, low accumulation of nitrite and ammonium, and good removal effect on rare earth elements. Moreover, the study identified the main denitrification genera and confirmed the role of extracellular polymeric substances (EPSs) in rare earth element removal. Overall, the study provides a reference for the application of permeable reactive barrier technologies with SAD composite fillers in rare earth mine engineering.
WATER AIR AND SOIL POLLUTION
(2023)
Review
Geochemistry & Geophysics
Marouen Jouini, Alexandre Royer-Lavallee, Thomas Pabst, Eunhyea Chung, Rina Kim, Young-Wook Cheong, Carmen Mihaela Neculita
Summary: This study compares and evaluates the environmental and social impacts of primary and secondary sources of rare earth elements (REEs) production. The results show that production from secondary sources has lower environmental impact. Important impact categories related to particulate matter formation, abiotic resource depletion, and fossil fuel depletion could be mitigated by avoiding tailings disposal. Therefore, increasing the recycling of secondary REE sources is encouraged to balance demand and resource exploitation.
Article
Chemistry, Applied
Xiaorui Wang, Wei Cheng, Renda Xu
Summary: This study investigates the adsorption behaviors of rare earth elements (REY) on organic matter in coal through leaching tests and molecular simulation calculations. The results show that the organic matter in coal has a strong adsorption capacity for heavy rare earth elements (HREY) compared to light rare earth elements (LREY). The molecular simulation calculations also confirm the advantage of HREY in adsorption on organic matter. These findings are of great significance for the application of rare earth elements in coal-based resources.
JOURNAL OF RARE EARTHS
(2023)
Article
Engineering, Chemical
Qiuting Yan, Zhenjun Zhang, Zuliang Chen
Summary: In this study, microbial synthesized iron nanoparticles after the recovery of rare earth elements (FeNPs/REEs) were used as an environmentally friendly material to remove arsenic from mine groundwater. The removal efficiencies of FeNPs/REEs were higher than those of FeNPs, and the removal mechanism involved surface complexation, oxidation, electrostatic, and ion exchange. The study provides new insights into the use of FeNPs/REEs for groundwater remediation.
SEPARATION AND PURIFICATION TECHNOLOGY
(2023)
Article
Environmental Sciences
Seyyed Saeed Ghannadpour, Ardeshir Hezarkhani
Summary: The association between rare earth elements and uranium occurrences in Central Iran has been explored in this study. By investigating a Skarn mine, the study proposes a new exploration method and sampling pattern for rare earth elements based on their correlation with radioactive elements.
ENVIRONMENTAL EARTH SCIENCES
(2022)
Article
Environmental Sciences
Guoqiang Wu, Nan Shi, Tao Wang, Chin-Min Cheng, Jiawei Wang, Chunxiao Tian, Wei-Ping Pan
Summary: Coal ash has been identified as an important alternative source of rare earth elements (REEs). This study investigated the enrichment and occurrence form of REEs in coal ash, specifically in coal fly ash (CFA) from power plants. The findings revealed the higher enrichment ratio of REEs in CFA compared to ashes from muffle furnace, which was attributed to several factors including the fractionation of coal ashes, higher combustion temperature, and longer residence time of fly ash. The study also highlighted the important role of aluminum in the occurrence form of REEs in CFA. These experimental and computational results provide valuable insights for understanding the distribution of REEs in CFA and optimizing their extraction processes.
ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH
(2022)
Article
Energy & Fuels
Vinoth Kumar Kuppusamy, Maria Holuszko
Summary: The applicability of sulfuric acid baking followed by water leaching (ABWL) for enhancing rare earth element (REE) leaching recovery from coal tailings was investigated in this study. The results showed that ABWL significantly improved REE extraction, reaching around 80% recovery. During the ABWL process, rare earth minerals in the sample were transformed into easily soluble rare earth sulfates.