Search Results (159)

The Xiangshan Uranium Mining Area in Jiangxi Province is a pivotal uranium extraction site crucial for China’s nuclear sector. However, vegetation ecology research in this region remains scarce, particularly studies grounded in multi-source remote sensing data. To overcome these challenges, this paper introduces a methodology that combines multi-source remote sensing data with the random forest machine learning algorithm to invert vegetation canopy structure parameters in the Xiangshan Uranium Mining Area. This approach is complemented by the integration of multiple vegetation indices for a comprehensive evaluation. To guarantee the dependability of the inversion results, this study employs Sentinel-1/2 imagery and ICESat-2 spaceborne LiDAR data, which furnish abundant optical information, terrain data, and vertical vegetation structure insights. The experimental findings reveal that the overall vegetation ecology in the Xiangshan Uranium Mining Area is in a satisfactory state, yet the low Radar Vegetation Index (RVI) hints at potential soil degradation concerns within the mining area. Furthermore, notable disparities in vegetation canopy structure between the mining area and the comparison zone underscore that the presence of mining deposits indeed exerts a potential influence on vegetation canopy structure. This study bridges the research gap and offers scientific support for mineral exploration and sustainable mining development. Full article

The sustainable development of nuclear energy requires a secure long-term uranium supply. Seawater uranium extraction offers a nearly inexhaustible resource; however, its commercialization is limited due to high costs. To improve economic viability, this study proposes a synergistic strategy for simultaneously recovering uranium and vanadium using amidoxime-based adsorbents, with vanadium as a valuable co-product. Herein, a porous silica-supported poly(amidoxime) adsorbent was synthesized and characterized. The material possesses a well-developed porous structure with a specific surface area of 49.8 m² g⁻¹. Spectroscopic analyses confirmed the successful grafting of amidoxime groups onto the silica framework, whereas X-ray photoelectron spectroscopy revealed that uranium adsorption occurs via coordination with nitrogen and oxygen donor atoms. Batch experiments demonstrated rapid adsorption equilibrium within 2 h and a maximum Langmuir uranium capacity of 48.5 mg g⁻¹ at 45 °C. The adsorbent exhibited high selectivity toward uranium over vanadium and competing ions at near-neutral pH. Dynamic column experiments demonstrated efficient stepwise separation using 0.1 mol L⁻¹ HNO₃ for uranium and a Na₂CO₃–H₂O₂ system for vanadium, even in simulated seawater containing high concentrations of competing ions. Under the controlled model conditions employed, this study demonstrates a promising adsorbent and a feasible co-recovery strategy that may contribute to enhancing the economic feasibility of seawater uranium extraction, warranting further validation in natural seawater. Full article

Interest in improved disposal pathways and proliferation-resistant systems for used nuclear fuel recycling has driven research on monoamide extractants. Existing comparisons against the industry standard, tributyl phosphate (TBP), emphasize a fundamental approach and span a wide range of test conditions. This work narrows that range and addresses process-scale considerations by presenting hydrodynamic performance results alongside extraction capacity at optimized conditions. The monoamide solvents, 1.0 M DEHiBA (N,N-di(2-ethylhexyl)isobutanamide), 1.5 M DEHBA (N,N-di(2-ethylhexyl)butanamide), and 1.5 M DEHDMPA (N,N-di(2-ethylhexyl)-2,2-dimethylpropanamide), are compared to 1.1 M TBP in bench-scale extraction tests with nitric acid (2–6 M) and uranium (∼0.8 M). Performance is assessed with distribution ratios and dispersion number ratings and supported by specific gravity and viscosity measurements. DEHBA and DEHDMPA exhibited inadequate coalescence behavior with failed or poor dispersion ratings despite uranium distribution ratios of 2.06 ± 0.03 and 0.86 ± 0.01 at O/A = 1.9, limiting suitability for process application. TBP and DEHiBA maintained adequate dispersion ratings across all conditions tested, with maximum distribution ratios of 4.37 ± 0.08 at O/A = 2.6 and 0.67 ± 0.01 at O/A = 2.9, respectively. Higher viscosity values for DEHBA (5.21 cP ± 0.3%) and DEHDMPA (6.53 cP ± 0.4%) relative to TBP (2.04 cP ± 0.4%) and DEHiBA (3.18 cP ± 0.4%) correlate with observed coalescence deficiencies. The methods presented in this work demonstrate the significance of evaluation beyond extraction capacity. Full article

Sandstone-type uranium deposits represent one of the most significant uranium deposit types in China, predominantly hosted in Meso-Cenozoic sedimentary basins in the northern part of the country. Due to characteristics such as deep burial of orebodies, fine grain size of ores, and strong heterogeneity, traditional geological logging methods have limitations in rapidly and accurately identifying alteration minerals and mineralization indicator information. Core spectral technology (wavelength range approximately 400–2500 nm), particularly short-wave infrared spectroscopy (SWIR, 1300–2500 nm), enables rapid, non-destructive, and quantitative extraction of alteration mineral information from drill cores. This provides robust technical support for reconstructing metallogenic environments, delineating oxidation–reduction zones, and prospecting and prediction in sandstone-type uranium deposits. This review systematically examines the spectral absorption characteristics and geological significance of key alteration minerals (e.g., clay minerals, carbonate minerals, iron oxides, and hydrocarbon substances) in sandstone-type uranium deposits. It elaborates on the current application status of core spectral technology in sandstone-type uranium exploration within typical basins in northern China, such as the Ordos, Songliao, Erlian, and Qaidam Basins. These applications include alteration mineral mapping, oxidation–reduction zone delineation, and metallogenic fluid tracing. Due to the unique characteristics of host rock lithology, alteration mineral assemblages, and fluid properties in sandstone-type uranium deposits, the application of this technology also faces certain challenges, such as difficulties in spectral interpretation and insufficient accuracy in quantitative inversion. Integrating this technique with multiple methods, including petrography and X-ray diffraction (XRD), will facilitate more effective applications in both metallogenic research and prospecting practices for sandstone-type uranium deposits in northern China. Full article

Uranium is a resource with exceptionally high energy density, releasing substantially more energy per unit mass than conventional fossil fuels. In uranium mining, in situ leaching offers significant advantages over open-pit and underground mining, including reduced environmental impact, lower operational costs, enhanced safety, and improved controllability. Within the in situ leaching framework, acid leaching faces limitations in high-carbonate ore bodies, while alkaline leaching is unsuitable for deposits rich in pyrite and other sulfide minerals due to side reactions and precipitate formation that hinder leaching efficiency. In contrast, CO₂-O₂ leaching, as a neutral leaching approach, exhibits broader applicability across diverse ore types and geological settings. Incorporating CO₂ into the leaching process also enables carbon utilization, offering a potential pathway to cleaner uranium extraction aligned with carbon reduction and sustainable energy goals. This review systematically examines the geochemical principles, as well as hydrological and transport phenomena governing CO₂-O₂ in situ leaching. Recent technological advances are summarized, including progress in reaction kinetics and leaching efficiency, leaching solution design and control, and reservoir modification. Furthermore, the techno-economic implications of CO₂-O₂ in situ leaching are critically assessed, with particular emphasis on operational cost structures and the evolution of techno-economic analysis methodologies. On this basis, key challenges and future directions are identified. This work aims to support the future large-scale and economically efficient deployment of CO₂-O₂ in situ leaching for uranium resource development. Full article

Uranium is a critical raw material for the nuclear industry. Given the vast uranium reserves in seawater, the development of efficient adsorbents is central to extraction technologies. Polyamidoxime (PAO)-based adsorbents are widely utilized due to their high affinity for uranium; however, traditional PAO materials often suffer from low mechanical strength and poor recyclability. To address these limitations, this study utilized natural balsa wood as a substrate. A three-dimensional porous cellulose skeleton (DES-W) featuring high porosity, hydrophilicity, and retained mechanical strength was constructed by partially removing lignin using a deep eutectic solvent (DES). Subsequently, polyamidoxime was loaded onto the inner walls of the DES-W via vacuum impregnation, resulting in a polyamidoxime-functionalized wood-based adsorbent (PAO-WA). The results indicated that PAO-WA achieved an equilibrium adsorption capacity of 45.31 mg/g at pH 6.0 with an initial uranium concentration of 50 mg/L, representing a twofold increase compared to the unmodified DES-W. The adsorption kinetics and isotherms followed the pseudo-second-order and Langmuir models, respectively, suggesting a mechanism dominated by monolayer chemisorption. Mechanism analysis confirmed that uranyl ions were primarily captured via coordination with nitrogen and oxygen atoms in the amidoxime groups, with residual carboxyl groups in the wood contributing to the adsorption process. This work offers a novel strategy for developing efficient, environmentally friendly, and mechanically robust adsorbents for uranium extraction from seawater. Full article

Uranium tailings, the primary solid waste from uranium production, are characterized by vast quantity, high radioactivity, and substantial environmental risks. This study systematically investigated a combined magnetic separation–reverse flotation process for extracting quartz from uranium tailings. Process mineralogical analyses, including XRD, MLA, and XRF, revealed that the tailings are mainly composed of quartz, potassium feldspar, albite, and almandine, with quartz accounting for approximately 43% and non-magnetic/weakly magnetic materials making up 91.06% of the total. The experimental results showed that after high-intensity magnetic separation at 1.8 T, the SiO₂ grade increases to 76.36%. Under the conditions of pH 2, a mixed collector system of sodium oleate and dodecylamine at a mass ratio of 1:7, and a total dosage of 2000 g/t, the SiO₂ grade further rises to above 90%. This work proposes a green process route for extracting quartz from uranium tailings, which not only achieves a reduction in radioactive tailings but also successfully obtains high-grade quartz products. Full article

Nuclear energy has become a promising substitute for traditional fossil fuels (e.g., coal, oil, and natural gas) by reason of its ultra-high energy density, firm power generation, and near-zero carbon emissions. However, the shortage of uranium resources is threatening the sustainable development of nuclear power, and meanwhile the nuclear fuel front-end cycle inevitably causes radioactive uranium-bearing wastewater discharge, resulting in severe environmental pollution. Nowadays, the extraction and enrichment of uranium in seawater and uranium-containing wastewater offer a prospective avenue to secure the long-term viability of nuclear power with environmental conservation. Among numerous strategies, photocatalytic extraction of soluble hexavalent uranyl (U(VI)) over graphitic carbon nitride (g-C₃N₄), a conjugated polymer semiconductor, is increasingly attracting widespread attention due to its high solar energy utilization, environmental friendliness, high selectivity, good stability, and low cost. A comprehensive overview that pinpoints research directions for novice researchers is urgently required. Herein, the development progress of g-C₃N₄-mediated photocatalytic U(VI) extraction is briefly introduced. Subsequently, the possible mechanisms are discussed with the assistance of advanced characterization techniques, and the influential factors for catalytic efficiency are also discussed. Moreover, multiple applications of g-C₃N₄-based catalysts on photocatalytic U(VI) reduction and extraction are elaborated, especially for modularization approaches on a large scale. At length, the future challenges and prospects in photocatalytic uranium extraction from water bodies are proposed. This review aims to offer fundamental insights into designing and exploring novel g-C₃N₄-based photocatalysts for soluble U(VI) enrichment in water bodies, especially opening up new avenues for the future development of sustainable uranium extraction technologies in practice. Full article

The modern development of the energy and metallurgy industries is accompanied by the increasing use of coal in the form of fuel and raw material. However, at the same time, urgent issues are arising concerning assessments of its radiological and environmental safety. Coal and ashes accumulate natural radionuclides (such as thorium, uranium, and potassium-40), and toxic and rare earth elements (REEs) that are capable of migrating into the environment during the processes of production, burning and ash disposal. Special attention has recently been paid to rare earth elements that are of economic value as critical metals for sophisticated technologies, but these can pose environmental risks. Their presence in coal is becoming an increasingly relevant issue for cross-disciplinary research, at the intersection of geochemistry, radioecology and the sustainable use of natural resources. Moreover, issues regarding the radiological safety of coal deposits and their derivative products are especially crucial for Kazakhstan, Russia, China and other countries with developed coal production industries. Studies demonstrate that ash and slag of thermal power plants can comprise increased concentrations of natural radionuclides that can accumulate in soil, water and the environment. Therefore, the study of rare earth, toxic and radioactive element contents in coal using nuclear analytical methods is of high practical and environmental significance, especially in terms of assessing radiation load on the environment, designing control measures and ash disposal, and the prospect of the selective extraction of REEs from the coals. Full article

The growing global demand for clean and sustainable energy has reignited interest in nuclear power as a carbon-free alternative to fossil fuels, driving an increase in uranium mining. However, uranium extraction releases radioactive elements along with toxic and heavy metals, posing serious environmental risks. A combined narrative and systematic review was employed to evaluate remediation mechanisms, performance trends, sustainability, and emerging technological advancements. The results indicate that phytoremediation remains the most extensively studied and field-applicable technique, while phycoremediation offers rapid uptake in aqueous systems and mycoremediation demonstrates higher tolerance to extreme conditions. However, limitations such as slow remediation rates, site-specific performance, and scalability challenges restrict their widespread implementation. This study also highlights the emerging role of artificial intelligence and machine learning in optimizing remediation processes, although their application remains limited, particularly in fungal systems. Furthermore, the integration of nature-based solutions into nuclear waste management frameworks, aligned with international safety standards, presents a promising pathway for sustainable remediation. Future research should focus on developing hybrid remediation strategies, establishing performance thresholds under high contamination conditions, and advancing AI-driven, site-specific optimization models to enhance efficiency and scalability. Full article

The extraction of rare earth elements is becoming increasingly essential due to their many applications in current and emerging advanced material technologies. However, in many rare earth deposits, rare earth minerals are associated with radionuclides; specifically, thorium and uranium. The radioactive nature of these elements is a major concern during processing. Techniques such as solvent extraction and precipitation have been employed in this regard to minimize the radioactivity levels and address any related processing or environmental concerns. However, they face various challenges such as high chemical reagent consumption, secondary waste generation, and limited selectivity, which hinder either their scalability or sustainability. The current study provides a literature review about these technologies to provide critical insights on their applications and discuss the challenges hampering their extensive use in the mining industry. Biotechnology is also evaluated and highlighted as a promising, cost-effective, and low-environmental-impact option for the selective recovery of radionuclides from rare earth elements. Specifically, pyoverdine siderophores were discussed due to their catecholates and hydroxamate moieties which have high affinity for radionuclides to enhance selective recovery during rare earth processing. Conversely, integration of this approach into existing mineral processing flowsheets is a constraint. Hence, future studies should focus on optimizing the kinetics of siderophore synthesis and explore a hybrid approach to combine the biotechnological and conventional techniques. Full article

The exploit of an efficient method for uranium (U) extraction is crucial for the development of nuclear energy. In this study, an aminated lignin-based microsphere (AL-PEI/GMS) was synthesized and used as an adsorbent for the recovery of hexavalent uranium (U(VI)) from salt-lake brine. The effects of adsorbent dosage, initial solution pH value, interfering ions, adsorption time, and temperature on the U(VI) adsorption performance of AL-PEI/GMSs were systematically investigated. The results show that when the adsorbent dosage was 2 g/L, the temperature was 45 °C, and the pH was 8, the adsorption capacity of AL-PEI/GMS for U(VI) could reach 256.4 mg/g. In addition, after five cycles, a high U(VI) adsorption efficiency of over 90% could still be achieved. Furthermore, through a fixed-bed system, AL-PEI/GMS could rapidly adsorb U(VI) from actual salt-lake brine. Therefore, the prepared AL-PEI/GMS is a competitive alternative material compared with other adsorbents in terms of efficiently recovering U(VI) from actual salt-lake brine. Full article

Thorium has emerged as a promising alternative to uranium in nuclear energy systems due to its higher natural abundance, favorable conversion to fissile ²³³U, and reduced generation of long-lived transuranic waste. This review provides a comprehensive overview of advanced techniques for thorium recovery from primary ores and secondary resources. The main mineralogical carriers—including monazite, thorianite, thorite, and cheralite as well as industrial by-products such as rare-earth processing tailings—are critically examined with respect to their occurrence and processing potential. Physical enrichment methods (gravity, magnetic, and electrostatic separation) and hydrometallurgical approaches (acidic and alkaline leaching) are analyzed in detail, highlighting their efficiencies, limitations, and environmental implications. Particular emphasis is placed on modern separation strategies such as solvent extraction with organophosphorus reagents, diglycolamides, and ionic liquids, as well as extraction chromatography, nanocomposite sorbents, ion-imprinted polymers, and electrosorption on carbon-based electrodes. These techniques demonstrate significant progress in enhancing selectivity, reducing reagent consumption, and enabling recovery from low-grade and secondary feedstocks. Environmental and radiological aspects, including waste minimization, immobilization, and regulatory frameworks, are discussed as integral components of sustainable thorium management. Finally, perspectives on hybrid technologies, digital process optimization, and economic feasibility are outlined, underscoring the need for interdisciplinary approaches that combine chemistry, materials science, and environmental engineering. Collectively, the analysis highlights the transition from conventional practices to integrated, scalable, and environmentally responsible technologies for thorium recovery. Full article

The development of effective materials for uranium extraction from seawater is vital for advancing sustainable energy solutions. However, the efficient recovery of uranium from seawater presents significant challenges due to its extremely low concentration, the presence of competing ions, and the complex marine environment. To address these issues, various materials such as inorganic and organic sorbents, chelating resins, nanostructured sorbents, and composite materials have been explored. More recently, the functionalization of carbon-based materials for enhanced adsorption properties has attracted much interest because of their high specific surface area, excellent chemical and thermal stability, and tunable porosity. These materials include activated carbon, graphene oxide, biochar, carbon cloths, carbon nanotubes, and carbon aerogels. The enhancement of carbonaceous materials is typically achieved through surface functionalization with chelating groups and the synthesis of composite materials that integrate other high-performance sorbents. This review aims to summarize the work of these functionalized carbon materials, focusing on their adsorption capacity, selectivity, and durability for uranium adsorption. This is followed by a discussion on the binding mechanisms of uranium with major chelating functional groups grafted on carbonaceous sorbents. Finally, an outlook for future research is suggested. We hope that this review will be helpful to researchers engaged in related studies. Full article

Exploring materials for the uranium extraction from seawater holds great significance for the sustainable development of the nuclear industry. Though many adsorbents have been investigated to extract uranium, they still suffer from the issues of low adsorption performance and high production cost. In this work, biomass nanofiber adsorbents (PA-CS NFs) were prepared by the electrospinning of chitosan followed by functionalization with phytic acid. Based on the cost analysis, the preparation expense of PA-CS NFs was $16.4 kg⁻¹, lower than those of common synthetic polymer adsorbents. In addition, PA-CS NFs showed fast removal kinetics (equilibrium time = 60 min), high uptake capacity (457.8 mg g⁻¹), and good selectivity (the ratio of uranium/competing ion capacities > 3.8) from uranium spiked solution. PA-CS NFs also exhibited the ability to remove trace uranyl ions (distribution coefficient = 4.7 × 10⁵ mL g⁻¹) and satisfy recycling capacity. The experimental tests and theoretical calculations confirmed that the phosphate groups in the functionalized phytic acid displayed the main contribution to the uranyl ion adsorption, which had higher binding energy than the functional groups in chitosan. Benefiting from the good adsorption ability, low cost, and macroscopical membrane form, PA-CS NFs were applied to natural seawater for uranium extraction, and an extraction capacity of 4.52 mg g⁻¹ could be achieved after 35 days’ testing. On account of the obtained results, this study offers an efficient and low-cost nanofiber adsorbent for uranium extraction. Full article