Uranium Mining Research Articles

Porous frameworks for uranium extraction from seawater

The utilization of uranium (U) fission energy as a high-density, clean power source plays a pivotal role in mitigating greenhouse gas emissions. Uranium extraction from seawater exhibits superior environmental friendliness compared to terrestrial uranium mining, as it avoids substantial generation of radioactive waste and harmful chemicals. However, conventional adsorbents such as fiber, polymer, and biomass materials exhibit slow adsorption rates and low ion selectivity. Porous frameworks with large inner surface, full host-guest interaction, and site utilization are utilized to improve uranium absorption performance. Consequently, devising and synthesizing materials that enable efficient and cost-effective extraction of U(VI) from seawater poses a formidable challenge. Recently, there has been a considerable surge in academic interest regarding the synthesis and design of porous frameworks. By integrating experimental data, spectroscopic analysis, and theoretical calculations, we have conducted an extensive investigation into the actual performance, underlying principles, and practicality of conventional materials (such as fibers) and novel porous materials serving as adsorbents, photocatalysts, and electrocatalysts for U(VI) extraction from seawater.

Neotectonic controls on large-scale uranium mineralization in the Meso-Cenozioc basins, Northern China

Neotectonic controls on large-scale uranium mineralization in the Meso-Cenozioc basins, Northern China

Unraveling the genetic type and metallogenetic mechanism of the oldest uranium deposit associated with granitoid, South China: A comprehensive analysis of whole-rock geochemistry, and elemental and U-Pb isotopic signatures of uranium minerals

The Daliang deposit in the Motianling area of South China is unique for its synchronous uranium mineralization with regional metamorphism. To elucidate its genetic mechanism, whole-rock geochemistry from the Daliang deposit was undertaken, along with analyses of the chemical and isotopic signatures of minerals. The Motianling granitoids exhibit strongly peraluminous S-type affinities with low Th/U ratios, representing a uranium source for mineralization. Altered mineralogical and geochemical signatures of altered and ore samples indicate a multi-stage history after granitic emplacement: (1) Late magmatic-hydrothermal alteration characterized by greisenization, K-feldspathization, and propylitization; and (2) brittle-ductile deformation with uranium mineralization. Notably, ore-stage alteration mineral contains chlorite + quartz + sericite, which is consistent with the mineral assemblage of low-greenschist facies metamorphism. EMPA and LA-ICPMS dating on pitchblende yielded ages of 378 and 380 Ma, coinciding with the timing of regional ductile deformation. The pitchblende exhibits weak fractionation between LREEs and HREEs and negative Eu anomalies, mirroring characteristics observed in syn-metamorphic uranium deposits. Therefore, we suggest that uranium mineralization within the Daliang was related to crustal metamorphism, and the Daliang deposit belongs to syn-metamorphic deposit. Fluids likely have been liberated from the acidic brines-bearing Sibao Group that underwent low-greenschist facies metamorphism. Paleozoic intracontinental orogeny in South China resulted in brittle-ductile deformation in the Motianling pluton. These zones provided favorable pathways for the migration of ore-forming fluids and subsequent uranium mineralization. Late Devonian retro-metamorphism facilitated the percolation of oxidizing metamorphic fluids into the Motianling granitoids, circulating along the pre-existing brittle-ductile zones. This study presents the first evidence for syn-metamorphic uranium deposits within the granite of South China. This finding suggests potentially distinct mineralization mechanisms compared to traditional granite-related uranium deposits in the region, warranting further investigation.

“Energy‒environment” life cycle assessment and comparison of a nuclear-based hydrogen production system

The use of fossil fuels has caused a global environmental catastrophe. To determine whether low-emission hydrogen to replace fossil fuels can successfully reduce environmental pollution, a comprehensive quantitative analysis of the product's whole industrial chain is necessary. This study proposes evaluating the environmental impacts of a pressurized water reactor (PWR) nuclear-based hydrogen production system using SimaPro and its database based on the life cycle assessment (LCA) method. The system covers fuel (uranium mine) production and use, equipment manufacturing and operation, factory construction and operation, and vehicle production and operation in hydrogen transportation. The emissions of 10 kinds of pollutants in the above four stages are calculated and classified into 6 environmental impact indicators for comprehensive analysis. The results show that the comprehensive energy recovery ratio of existing feasible high-temperature electrolysis (HTE) technology is 17.65%, which is 68% higher than the efficiency of conventional electrolysis (CE) technology. The global warming potential (GWP) of 1 kg H2 produced by PWR-HTE is 2.18 kg CO2 eq, of which the construction, operation, and transportation stages account for 9.6%, 30.7%, and 58.7%, respectively. Except for GWP, the operation stage contributes the highest environmental impact. Energy transition and hydrogen transportation distance are the key parameters with great environmental impacts on the system. Based on the above LCA quantitative research and assessment results, policy development recommendations are proposed for the clean nuclear-hydrogen industry.

Assessment of the Level of Radioactivity in the Soil in Urban Areas and Building Materials of Arlit City (Agadez-NIGER)

Niger's uranium deposits are located in the north, bordering the southern Sahara. Mining activities led to the creation of the town of Arlit in 1969. Uranium mining and uranate production generate large volumes of radioactive solid and liquid tailings, as well as radioactive gases. Through dispersion and transport, these radioactive discharges become a source of contamination to the environment and food chain. The aim of our work is to assess the additional ambient exposure to radioactivity of surrounding populations as a result of mining activities. We assessed the risk of exposure to radionuclides from the uranium-238 decay chain through soil and certain building materials. The methodology used is based on collection of soil, sand, gravel and mud samples, which are analyzed using gamma spectrometry technique. Nine (9) public sites and five (5) building materials quarries were sampled for the work. The radiological parameters calculated are radium equivalent activity (Raeq), absorbed dose rate (D), internal and external risk indices (Hin and Hex) and gamma index (Iγ). For the whole study area, the calculated Raeq values range from 78.67 Bq/kg to 199.32 Bq/kg. These values are below the guideline value of 370 Bq/kg. In terms of air dose rate, however, the average value found was 0.32 mSv/year for the nine public sites considered. This exceeds the threshold value of 0.29 mSv/year corresponding to the selected exposure scenarios. In addition, in the mud (Quarry 5) and the second gravel quarry (Quarry 4), Iγ values greater than unity were found. A comparison is made with the results of similar studies around the world. Interpretation of the data obtained concludes that there is a risk of radiological overexposure at six (6) sites and two (2) quarries. This work is independent research which sheds new light on the issue of uranium mining activities impact on the environment in Arlit.

Modification of the LSC method for determination of uranium in water

Uranium is a lithophile, reflecting its tendency to remain close to the earth's surface and be strongly bound to oxygen.A standard method ISO 13169:2018(E) “Water quality — Uranium — Test method using alpha liquid scintillation counting” is usually used for the determination of activity concentration of uranium in water samples by liquid scintillation counting. This paper presents the results of the modified application of the mentioned standard method and calibration results of LS counter Quantulus 1220, PerkinElmer. The applicability of the method was tested by using three different “two-phase” (water immiscible) scintillation cocktails produced by PerkinElmer: Ultima Gold F, Mineral Oil and Opti Fluor – O. For calibration purposes we used a natural uranium liquid calibration source, certified by Czech Metrology Institute, Prague. The innovation in the presented approach is that this calibration source was used as both alpha and beta emitter. As a first step in the calibration of the detector the discriminator factor, PSA was adjusted for each of the used scintillation cocktails. This step ensures the appropriate separation of alpha counts from beta counts in the obtained spectra.The obtained efficiencies for each of the scintillation cocktails are: for Ultima Gold F 75.6 (10)%, for Opti Fluor O 68 (9)% and for Mineral Oil 86 (6)%. The minimal detectable activities for the measuring time of 600 min are: for Ultima Gold F around 1 Bq/l, for Opti Fluor O 1.5 Bq/l and for Mineral Oil 1.3 Bq/l. In order to test the developed methodology samples of known activities were prepared with standard reference material and measured with all three scintillation cocktails. In addition to that, two samples of natural water from a former uranium mine were tested and gamma spectrometry results of the surrounding soil samples are also presented.

Efficient removal of uranium and sulfate in acid contaminated groundwater by flow electrode capacitive deionization

In-situ leaching (ISL) causes non-negligible groundwater pollution. It is urgent to remediate the groundwater after ISL activities. In this study, we evaluated the effectiveness of flow electrode capacitive deionization (FCDI) to treat a simulated groundwater, the uranium (U) and SO42− concentration of which are comparable to groundwater in acid in-situ leaching (AISL) uranium mine for the first time. Moreover, the removal mechanism of U and SO42− were investigated in-depth. It is found that the operational mode, applied voltage and initial SO42− concentration significantly affect the removal of U and SO42− by FCDI. The removal efficiency of U and SO42− were above 98 % at 75 min under optimal condition, although U in groundwater mainly existed in the form of uncharged UO2(SO4), followed by UO22+ and UO2(SO4)22−. UO22+ and UO2(SO4)22− in groundwater migrated into the two poles and were quickly absorbed by flow electrode, which promoted the dissociation of UO2(SO4) or complexation of UO2(SO4) with SO42−. In addition, the anion exchange membrane can absorb UO2(SO4) through complexation. These resulted in the efficient removal of U(VI). FCDI can reduce the U and SO42− concentration of the contaminated water (CU = 10 mg L−1, CSO42− = 5 g L−1) to a value lower than the Chinese emission limit (U: 300 μg L−1; SO42−: 250 mg L−1) even after 18 cycles with each cycle operated for 120 min, which informed that FCDI system using activated carbon is of great potential for acidic contaminated water treatment.

Characterization of Excavated Radionuclide Retention Ponds in a Uranium Mine in the Process of Decommissioning Using Geophysical Methods

Characterization of Excavated Radionuclide Retention Ponds in a Uranium Mine in the Process of Decommissioning Using Geophysical Methods

A Review on Uranium Mineralization Related to Na-Metasomatism: Indian and International Examples

Uranium mineralization related to Na-metasomatism is known as Na-metasomatite or albitite-type. They represent the fourth-largest uranium resource globally and constitute fifty thousand tons of U resources. The present work gives details about well-known Na-metasomatic uranium occurrences worldwide in terms of structures, metasomatic stages, geochemical characteristics, fluid inclusions, and compositions of stable isotopes. The host rocks are granite, granitoid, and metamorphosed volcano-sedimentary rocks, and these rocks experienced two/three deformational stages. U mineralization is mainly confined to faults and characterized by granitic intrusive, cataclasis, mylonitization, and albitization. The albitized rocks exhibit two to three metasomatic and late hydrothermal stages. The first stage is marked by the replacement of pre-existing host minerals during a ductile shear regime. The second stage is related to U mineralization contemporaneous with the brittle deformation. The albitized rocks exhibit depletion in Si, K, Ba, and heavy rare-earth elements relative to the host rocks and enrichments in Na, Ca, U, Zr, P, V, Sr, and light rare-earth elements. U-enrichment is positively correlated with Na, Mo, Cu, and high-field strength elements. The pressure–temperature (P-T) conditions of U mineralization are considered to be epithermal and mesothermal. Fluid inclusion studies indicate that the mineralizing fluids were rich in Na+, Mg2+, Cl−, CO2, H2O, F−, and PO43− and meteoric–magmatic derived. The geological processes responsible for the genesis of Na-metasomatic U deposits of the North Delhi Fold Belt (India) are comparable with some international examples, i.e., Australia, Ukraine, Cameroon, Brazil, Guyana, China, and the USA.

Phytoremediation of soil co‐contaminated with uranium and chromium by sunflower (Helianthus annuus L.) enhanced with slow‐release composite chelating agent (EDTA/ammonium citrate)

AbstractBACKGROUNDSoil in uranium mining areas is contaminated by uranium and associated heavy metals, posing a significant threat to human health and ecological security. Chelating agent assisted phytoremediation is a cost‐effective and ecologically friendly remediation approach for uranium and associated heavy metals contaminated soil. In this work, a novel slow‐release composite chelating agent (SRCMC‐g‐CMCD‐EDTA/AC) was fabricated using carboxymethyl chitosan‐graft‐carboxymethyl‐β‐cyclodextrin (CMC‐g‐CMCD) as a slow‐release carrier and EDTA/ammonium citrate (AC) as a composite chelating agent through the spray drying method, which was used for phytoremediation of soil co‐contaminated with uranium and chromium.RESULTSCMC‐g‐CMCD exhibited superior slow‐release performance for both EDTA and AC in comparison with CMC and CMCD. When applied to soil contaminated with uranium (U) and chromium (Cr), SRCMC‐g‐CMCD‐EDTA/AC effectively regulated the release of U and Cr. Sunflowers (Helianthus annuus L.) grown in treated soil showed a significant increase in U and Cr uptake by 70.55% and 35.55%, respectively, and reduced leaching losses by 34.88% and 37.42%.CONCLUSIONSRCMC‐g‐CMCD‐EDTA/AC not only assists in the phytoremediation of soil co‐contaminated with U and Cr but also reduces the risk of leaching into groundwater during the soil phytoremediation process. SRCMC‐g‐CMCD‐EDTA/AC‐assisted phytoremediation technology was an effective and environmentally friendly remediation means for the removal of U and heavy metals from contaminated soils in uranium mining areas. © 2024 Society of Chemical Industry (SCI).

Improvement of uranium adsorption in Kocuria rosea by phosphate: A combined physiological and proteomic analysis

In this study, a combined physiological and proteomic analysis was performed to investigate the effect of phosphate addition on uranium adsorption response of Kocuria rosea. When 0.4–5 g/L KH2PO4 was added to the culture medium, there was no significant change in biomass compared with the control (without KH2PO4 addition). Subsequently, the cells were collected and interacted with uranium solution (300 mg/L, 20 mL), and the adsorption rate of uranium was significantly increased from 22.14 % to 65.32 % with 3.0 g/L KH2PO4 addition. Meanwhile, the cells could release more phosphorus-containing substances and form thin film like uranium precipitates on the cell surface by fourier transform infrared spectroscopy and scanning electron microscopy characterization analyses. Furthermore, a proteomic approach was employed to reveal the regulation mechanism of phosphate on uranium interaction in the K. rosea cells. The bioinformatics analysis revealed that the differentially abundant proteins in K. rosea were mainly involved in cell motility, ribosomes, structural molecule activity, flagellar assembly, and energy metabolism under uranium stress. Interestingly, up-regulated proteins were significantly enriched for organic acid biosynthetic process in the cells with KH2PO4 addition. In addition, KH2PO4 led to upregulation of proteins including phosphohydrolase, asparagine synthase, and the phosphotransferase system (PTS) transporter subunit EIIC, which related to phosphate metabolism for regulation of uranium mineralization.

Community perceptions on socio-economic impacts of uranium exploration in Selous Ecosystem, Tanzania

Large-scale mining has positive and negative effects that impact people differently leading to varying perceptions. This study assessed perceptions of local communities on socio-economic impacts of uranium exploration in Selous Ecosystem, Tanzania. The study was guided by three main research questions (i) Are local communities aware of the impacts of uranium exploration? (ii) What are the socio-economic impacts of uranium exploration? and (iii) What are perceptions of local communities on uranium impacts? A simple random sampling technique was used to select 51 households for questionnaire survey. Additionally, 22 key informants were interviewed and 2 focus group discussions were conducted. Moreover, secondary information such as government policies, legislations, and previous published and unpublished reports were reviewed. The quantitative information was analysed through Statistical Package for Social Science. For the purpose of this study, descriptive statistics was used while qualitative information was analysed using content analysis technique. In terms of awareness, 51% were unaware on negative impacts of uranium mining. The positive socio-economic impacts reported were employment opportunities, improved quality of life, road accessibility and economic opportunities. However, the majority of people interviewed (70 %) claimed that they have not received individual benefits from uranium exploration activities. Perception differed significantly, with 72% of those employed in the mine having positive perceptions, compared to 62% of the unemployed individuals who had negative perceptions. This study recommends a community-based bottom-up approach for awareness raising on uranium impacts. In addition, the mining company should implement effectively its corporate social responsibilities because, the negative perceptions may stand as a hindrance for accomplishment of its goals. The findings of this study provide preliminary baseline for future studies to monitor the impacts of uranium in particular radioactivity pathways associated with uranium mining

Petrogenesis of U-rich two-mica granite from the Mesozoic Reshui pluton (Nanling Range, South China) with implications for uranium mineralization

Muscovite-bearing granites are the dominant rock type associated with metallic deposits in South China. Some of these granites are rich in U and considered potential sources for subsequent hydrothermal uranium mineralization. Although widely studied, the petrogenesis of muscovite-bearing granites remains obscure. The Reshui pluton contains fine-grained biotite granite and coarse grained two-mica granite (CGTG). CGTG exhibits high U concentrations (5.07–40.15 ppm, average 15.94 ppm) and is typical of U-rich granite in South China. We conducted detailed petrographic, geochemical and biotite mineralogical analyses of the CGTG from the Reshui pluton. Our findings provide new insights into the petrogenesis of U-rich granites in South China and their significance for uranium mineralization. LA-ICP-MS zircon U–Pb dating shows that the CGTG were formed at 167.3 ± 1.7 Ma. Integrated petrological, whole-rock geochemical and biotite geochemical data, the negative and limited variation of the εNd(t) values (from − 10.8 to − 9.6) and a two-stage Paleoproterozoic model age (1.72 to 1.83 Ga), suggest the U-rich S-type CGTG formed by partial melting of Paleoproterozoic clay-rich pelitic rocks and underwent extensive fractional crystallization. The U-rich pelitic magma sources characterized by relatively low oxygen fugacity and temperature, relatively high degree of magmatic differentiation and F content are the main factors controlling U enrichment in the Reshui pluton CGTG. The petrologic and whole-rock geochemical characteristics, together with the biotite chemical compositions and disseminated U-rich accessory minerals including uraninite, indicate that the CGTG in the Reshui pluton has a high uranium mineralization potential and should be given more attention in further explorations.

Petrological, mineralogical, carbonate C-O and sulfide S isotope study of the Bayinqinggeli sandstone-hosted uranium deposit in the northern Ordos Basin

Many sandstone-hosted uranium deposits have been discovered in the northern Ordos Basin, including the Bayinqinggeli deposit, exhibiting tremendous potential for uranium exploration and prospecting. This region is characterized by complex fluid activities, yet unknowns or controversies still exist regarding the source and properties of the fluids and their influence on uranium mineralization. In this study, we employed optical and scanning electron microscopy (SEM), X-ray diffraction (XRD), micro X-ray fluorescence (μ-XRF), C-O isotope of calcite, and in situ S isotope of pyrite, to investigate the genesis and evolution of the Bayinqinggeli deposit. Pyrite and calcite are closely associated with uranium minerals, and all exhibit distinct characteristics in rocks of varying grades. In high-grade mineralized rocks, ore-related pyrite, characterized by euhedral and colloidal forms, mainly predated uranium mineralization, evidenced by the extensive coffinite replacement. The mostly negative δ34S values with a broad range (−24.6 ‰ to 23.9 ‰; mean = −4.2 ‰) point to microbial sulfate reduction under restricted conditions. In low-grade and barren rocks, pyrite unrelated to mineralization, mainly as large granular or colloidal cement, shows generally positive δ34S values with a wide range (−49.5 ‰ to 67.4 ‰; mean = 15.3 ‰). This suggests the involvement of both biological and abiological processes during different stages, with the latter possibly associated with deep-sourced fluids. Considering the heterogeneous isotope compositions of sulfur in pyrite and carbon in calcite (δ13C ranging from −21.4 ‰ to −4.9 ‰), it can be deduced that the deposit was strongly affected by two types of fluids: (1) surface oxidizing fluids and (2) deep reducing fluids. The mineralizing fluids were derived from oxidizing surface water, which dissolved uranium ions, carbonates, and sulfates from weathered source rocks and during infiltration through the sandstone, resulting in the formation of abundant uranium minerals and associated pyrite and calcite. The presence of low δ13C calcite further corroborates the influence of deep hydrocarbon-bearing fluids, which played a protective role in post-ore stage preservation, corresponding to the widespread green alteration in the Lower Zhiluo formation. Overall, the development of sandstone-hosted uranium deposits is a continuous and progressive process, with early-formed mineralization being transformed by late-stage fluid events. Calcite has a significant impact on the formation, development, and extraction of uranium ores in the deposit, protecting the paleo-orebodies against remobilization and remigration. A significant portion of uranium ore is preserved by calcite cementation. Therefore, the careful management of carbonates during in situ leaching is essential for the effective extraction of uranium from the host sandstones.

Brazil's Uranium Mining Evolution: Domestic Developments and International Dynamics

This article provides an exploration of the historical trajectory of uranium mining in Brazil, providing insight into its emergence, development, and current status within the global nuclear landscape. From its early days, characterized by sporadic mining ventures to the establishment of strategic uranium reserves, Brazil's journey mirrors a complex interplay of domestic imperatives and international dynamics. However, despite Brazil's significant uranium resources and advances in nuclear technology, its narrative often remains overshadowed by other global nuclear actors. Thus, by delving into Brazil's historical engagement with uranium mining, this paper seeks to illuminate its evolving role and contributions to the nuclear domain. Furthermore, this study examines the impact of external influences, such as geopolitical pressures, the international price of uranium, and technological advancements, on Brazil's nuclear ambitions. Ultimately, it aims to enrich our understanding of Brazil's past, present, and future in the global nuclear area.

The role of hydrothermal alteration in uranium mineralization at the Xiaoshan uranium deposit, South China

Hydrothermal alteration can be utilized to constrain element migrations during mineralization, as it records the effects of fluid-rock interactions. Previous studies have suggested that uranium in deposits primarily originates from uranium-bearing granites; however, limited knowledge exists regarding the leaching mechamisms of this element and rare earth elements (REEs) from these rocks. In recent years, the Xiaoshan Deposit, a newly discovered medium-sized uranium deposit, has been discovered in the central part of the Lujing uranium ore field, South China. In this study, we examine this deposit to investigate hydrothermal alterations and their impact on elemental mass change. The deposit exhibits seven types of alteration including K-feldspar, albite, illite, sericite, muscovite, quartz and chlorite alteration. These alterations follow a certain sequence, starting from chlorite alteration, followed by widespread K-feldspar alteration, then to albite alteration, accompanied by muscovite alteration, and finally illite, sericite and quartz alteration. The main uranium mineralization stage was coeval with the late acid siliceous hydrothermal fluid, illite and sericite alteration. The pre-ore alkaline alteration (K-feldspar alteration) resulted in the leaching and extraction of uranium, leading to the precipitation of a significant amount of apatite in mineral interstices and initial uranium enrichment (ΔCi (U) = 16.52 ppm). This process facilitated material preparation for subsequent acidic alterations and localized ore enrichment. The original dense rock structure was disrupted, creating fractures/cavities that served as conduits for uranium mineralization. Moreover, under alkaline metasomatism, uranium and REEs was extensively leached out of uranium-bearing accessory minerals such as the apatite. According to apatite compositional variations and alteration geochemistry, these variations reveal the process of uranium dissolution, migration, and precipitation enrichment into ore bodies. Uranium was completely released during alkaline metasomatism, causing a sharp decline in U content from 53.1 ppm to 0.96 ppm. The formation of alkaline alteration fluids facilitates the extraction of uranium from the surrounding rocks (the Indosinian granite).

Southeastern extension of Singhbhum Shear Zone, Eastern Indian Shield: A detailed appraisal

Trans-crustal, northerly dipping, arcuate Singhbhum Shear Zone (SSZ) constituting the interface of Proterozoic North Singhbhum Mobile Belt (NSMB) and Singhbhum Craton (SC) is established over a strike length of about ∼200 km from Baharagorato Chakradharpur in the west beyond which it bifurcates around the wedge shaped Chakradharpur granite. Based on geological mapping and meso to micro scale structural analysis, present work examines the SSZ’s southeastern extension beyond Baharagora, indicating its southward continuation for about 50 km to Dubukidihi within the NSMB lithopackage. Bangriposi Shear Zone (BSZ) which defines the terrane boundary between the SC and NSMB in this sector, splays towards north as Bangriposi West Shear Zone (BWSZ) and both transects the Dhanjori Basin longitudinally. BSZ and BWSZ are interpreted to be cogenetic with SSZ. NSMB in this area comprises of pelitic and psamopelitic rocks intruded by mafic–ultramafic magmatism and granitoids. Considering a north to south compression regime during accretion of NSMB with SC, the study area, which forms the interface between the craton and mobile belt, is at an acute to obtuse angle with the direction of overall stress field. It is marked by several high strain zones characterized by N-S shear band cleavages with moderate easterly dips, and northerly pitching stretching/mineral lineation. Consistent westerly vergent folds on mylonitic plane and orientation of stretching lineation indicates top to WSW movement in the shear zones. Tectonically interleaved mafic–ultramafic schist within the Romapahari granite are sites of copper mineralization with enhanced nickel concentration pointing towards future exploration sites for epigenetic copper, uranium mineralization which is so characteristic of SSZ.

Fluid-rock reaction path modeling of uranium mobility in granite-related mineralization: A case study from the Variscan South Armorican Domain

The mobilization of uranium in granite-related systems presents a complex interplay of chemical and hydrodynamic factors. This is particularly obvious within syn-orogenic detachment zones where per descensum surface-derived fluids interact with per ascensum deeply sourced hydrothermal fluids. In this study, we employ a thermo-hydro-chemical (TH-C) modeling approach to explore the multifaceted processes that govern uranium transport and deposition in such environments. Our findings indicate that uranium mobility is not solely determined by the oxidizing nature of the percolating surface-derived fluids. Actually, the oxidation-reduction potential of these fluids varies as they flow in the crust, ultimately adjusting towards more neutral or mildly reducing conditions conducive to uranium dissolution and precipitation. Even in the presence of magnetite, which enhances the reductive potential of the fluids, uranium continues to dissolve, albeit in much smaller quantities, with U(IV) being the predominant species in the aqueous phase. The study highlights the crucial roles of temperature, pH, and fluid/rock interaction ratios in influencing uranium leaching efficacy. High fluid/rock ratios enhance uranium extraction from source rocks. A fluid/rock ratio around 1 is optimal, maximizing the dissolution of uranium-bearing minerals in the source rock and promoting the precipitation of uranium minerals in different locations along the fluid pathway due to changes in fluid chemistry. The TH-C modeling has the potential to be applied to a variety of other uranium deposits, developed below 300°C.

Electrochemical Drawdown of U3+ and Ce3+ in Molten LiCl-KCl Using a Liquid Cadmium Cathode

Abstract The electrorefining of spent nuclear fuels is a key step to recover uranium and transuranium on separated cathodes. However, the electrolyte salts become contaminated with fission products after batches of electrorefining, and therefore the two unit processes for the drawdown of actinide and lanthanide are suggested before treatment of the contaminated salts. We investigated the electrochemical drawdown of U3+, Ce3+, and U3+ from Ce3+ in molten LiCl-KCl electrolyte using a liquid cadmium cathode (LCC) at 773 K. The drawdown mechanism of U3+ and Ce3+ was determined by cyclic voltammograms and calculating the equilibrium potential. After galvanostatic electrolysis, high recovery yields were obtained for the drawdown of U3+ and Ce3+, but the current efficiency of Ce3+ was at least twice as high as that of U3+ due to the cyclic electrolysis of U3+/U4+. Despite significant underpotential deposition of Ce3+ in the LCC, an exceptional separation factor for Ce relative to U reached 84.67 ± 17.13, which was attributed to the formed pure uranium products hindering the subsequent deposition of Ce3+. Moreover, pure uranium products and Ce-Cd intermetallic compounds were characterized by X-ray diffraction and scanning electron microscope coupled with energy dispersive X-ray spectroscopy.

Uranium Mill Tailings Generation and Management Challenges

Uranium mining has been ongoing for the past 200 years, yet managing uranium waste remains a significant challenge. This difficulty arises due to strict regulations imposed on uranium-related industries, driven by the assumed health risks associated with radiation. As a result, much of the waste generated by nuclear industries is currently stored. In India, uranium mining and milling waste is stored that require large tracts of land and continuous monitoring. Given the high value of land in India and the potential expansion of uranium mining to meet net-zero emission targets, an effective solution for managing uranium mill tailings is urgently needed. Meanwhile, India's construction sector is rapidly growing that require a huge quantity of materials. This paper reviewed the history of uranium mining and mill tailings generation and propose that the construction industry could effectively utilize these tailings. This approach not only addresses resource scarcity but also promotes environmental sustainability by conserving natural resources, reducing ecological imbalances, and advancing a circular economy.