Search Results (229)

This study presents a comprehensive computational analysis of flow rate efficiency during uranium extraction via the In Situ Recovery method. Using field data from a deposit located in Southern Kazakhstan, a series of mathematical models were developed to evaluate the distribution and balance of leaching solution. A reactive transport model incorporating uranium dissolution kinetics and acid–rock interactions were utilized to assess the accuracy of both traditional and proposed methods. The results reveal a significant spatial imbalance in sulfuric acid distribution, with up to 239.1 tons of acid migrating beyond the block boundaries. To reduce computational demands while maintaining predictive accuracy, two alternative methods, a streamline-based and a trajectory-based approach were proposed and verified. The streamline method showed close agreement with reactive transport modeling and was able to effectively identify the presence of intra-block reagent imbalance. The trajectory-based method provided detailed insight into flow dynamics but tended to overestimate acid overflow outside the block. Both alternative methods outperformed the conventional approach in terms of accuracy by accounting for geological heterogeneity and well spacing. The proposed methods have significantly lower computational costs, as they do not require solving complex systems of partial differential equations involved in reactive transport simulations. The proposed approaches can be used to analyze the efficiency of mineral In Situ Recovery at both the design and operational stages, as well as to determine optimal production regimes for reducing economic expenditures in a timely manner. Full article

The aim of this study was to improve the efficiency of in situ uranium leaching by developing a specialized methodology for selecting rational parameters for the chemical treatment of production wells. This approach was designed to enhance the filtration properties of ores and extend the uninterrupted operation period of wells, considering the clay content of the productive horizon, the geological characteristics of the ore-bearing layer, and the composition of precipitation-forming materials. The mineralogical characteristics of ore and precipitate samples formed during the in situ leaching of uranium under various mining and geological conditions at a uranium deposit in the Syrdarya depression were identified using an X-ray diffraction analysis. It was established that ores of the Santonian stage are relatively homogeneous and consist mainly of quartz. During well operation, the precipitates formed are predominantly gypsum, which has little impact on the filtration properties of the ore. Ores of the Maastrichtian stage are less homogeneous and mainly composed of quartz and smectite, with minor amounts of potassium feldspar and kaolinite. The leaching of these ores results in the formation of gypsum with quartz impurities, which gradually reduces the filtration properties of the ore. Ores of the Campanian stage are heterogeneous, consisting mainly of quartz with varying proportions of clay minerals and gypsum. The leaching of these ores generates a variety of precipitates that significantly reduce the filtration properties of the productive horizon. Effective compositions and concentrations of decolmatant (clog removal) solutions were selected under laboratory conditions using a specially developed methodology and a TESCAN MIRA scanning electron microscope. Based on a scanning electron microscope analysis of the samples, the effectiveness of a decolmatizing solution based on hydrochloric and hydrofluoric acids (taking into account the concentration of the acids in the solution) was established for the destruction of precipitate formation during the in situ leaching of uranium. Geological blocks were ranked by their clay content to select rational parameters of decolmatant solutions for the efficient enhancement of ore filtration properties and the prevention of precipitation formation. Pilot-scale testing of the selected decolmatant parameters under various mining and geological conditions allowed the optimal chemical treatment parameters to be determined based on the clay content and the composition of precipitates in the productive horizon. An analysis of pilot well trials using the new approach showed an increase in the uninterrupted operational period of wells by 30%–40% under average mineral acid concentrations and by 25%–45% under maximum concentrations with surfactant additives in complex geological settings. As a result, an effective methodology for ranking geological blocks based on their ore clay content and precipitate composition was developed to determine the rational parameters of decolmatant solutions, enabling a maximized filtration performance and an extended well service life. This makes it possible to reduce the operating costs of extraction, control the geotechnological parameters of uranium well mining, and improve the efficiency of the in situ leaching of uranium under complex mining and geological conditions. Additionally, the approach increases the environmental and operational safety during uranium ore leaching intensification. Full article

Background/Objectives: This study aimed to evaluate the effects of lung injury induced by insoluble uranium oxide particles on gut microbiota and related metabolites in rats. Methods: The rats were randomly divided into six UO₂ dose groups. A rat lung injury model was established through UO₂ aerosol. The levels of uranium in lung tissues were detected by ICP-MS. The expression levels of the inflammatory factors and fibrosis indexes were measured by enzyme-linked immunosorbent assay. Paraffin embedding-based hematoxylin & eosin staining for the lung tissue was performed to observe the histopathological imaging features. Metagenomic sequencing technology and HM700-targeted metabolomics were conducted in lung tissues. Results: Uranium levels in the lung tissues increased with dose increase. The expression levels of Tumor Necrosis Factor-α (TNF-α), Interleukin-1β (IL-1β), Collagen I, and Hydroxyproline (Hyp) in rat lung homogenate increased with dose increase. Inflammatory cell infiltration and the deposition of extracellular matrix were observed in rat lung tissue post-exposure. Compared to the control group, the ratio of Firmicutes and Bacteroides in the gut microbiota decreased, the relative abundance of Akkermansia_mucinphila decreased, and the relative abundance of Bacteroides increased. The important differential metabolites mainly include αlpha-linolenic acid, gamma-linolenic acid, 2-Hydroxybutyric acid, Beta-Alanine, Maleic acid, Hyocholic acid, L-Lysine, L-Methionine, L-Leucine, which were mainly concentrated in unsaturated fatty acid biosynthesis, propionic acid metabolism, aminoacyl-tRNA biosynthesis, phenylalanine metabolism, and other pathways in the UO₂ group compared to the control group. Conclusions: These findings suggest that uranium-induced lung injury can cause the disturbance of gut microbiota and its metabolites in rats, and these changes are mainly caused by Akkermansia_mucinphila and Bacteroides, focusing on unsaturated fatty acid biosynthesis and the propionic acid metabolism pathway. Full article

Systematic studies were conducted at one of the uranium deposits in Kazakhstan. Native strains of Acidithiobacillus ferrooxidans bacteria were found in leaching solutions at the deposit. The modeling of iron species in the culturing medium was analyzed using Medusa software v.2.0.5. To intensify the process, the bacterial strains were propagated in laboratory conditions, and strains available in the laboratory were added. The ability of bacteria to oxidize divalent iron to trivalent iron at 8 °C in laboratory conditions was established, but the oxidation rate was low. It was found that the limiting stage of bioleaching use in deposit conditions is the temperature mode, the content of divalent iron, and oxygen. A biomass volume of 15 L was initially cultivated under laboratory conditions, and subsequently scaled up to 3 m³ in production using three 1 m³ pachucas with air aeration. In addition, pilot tests were carried out directly in production conditions and biomass in the volume of over 30 m³ was produced. The kinetics of the oxidation process of divalent iron to trivalent iron in 1 g/h under production conditions was established. The features of the bioleaching process at the field are shown as follows: since production, the solution contains the main microelements for the nutrition and reproduction of bacteria, and recommendations for the use of bioleaching are proposed. Research has established that under conditions of a shortage of divalent iron in the solution, sulfuric acid is formed due to sulfur-containing substances. It was observed that for the effective conversion of divalent iron to trivalent iron, bacteria of the provided strain and air (oxygen) supply are sufficient. The corresponding recommendations were issued during the work. Full article

Significant uranium exploration breakthroughs have been achieved in the eolian deposits of the uranium reservoirs in the southwestern part of the Ordos Basin. The redox environment remains a crucial factor in controlling the migration and precipitation of uranium. This study, through rock mineralogical observations and hydrocarbon gas composition analysis, combined with the regional source rock and basin tectonic evolution history, reveals the characteristics of the reducing medium and the mineralization mechanisms involved in uranium ore formation. The Lower Cretaceous Luohe Formation uranium reservoirs in the study area exhibit a notable lack of common reducing media, such as carbonaceous debris and pyrite. However, the total hydrocarbon gases in the Luohe Formation range from 2967 to 20,602 μmol/kg, with an average of 8411 μmol/kg—significantly higher than those found in uranium reservoirs elsewhere in China, exceeding them by 10 to 100 times. Due to the absence of other macroscopically visible organic matter, hydrocarbon gases are identified as the most crucial reducing agent for uranium mineralization. These gases consist predominantly of methane and originate from the Triassic Yanchang Formation source rock. Faults formed during the Indosinian, Yanshanian, and Himalayan tectonic periods effectively connect the Cretaceous uranium reservoirs with the oil and gas reservoirs of the Triassic and Jurassic, providing pathways for the migration of deep hydrocarbon fluids into the Cretaceous uranium reservoirs. The multiphase tectonic evolution of the Ordos Basin since the Cenozoic has facilitated the development of faults, ensuring a sufficient supply of reducing media for uranium reservoirs in an arid sedimentary context. Additionally, the “Replenishment-Runoff-Drainage System” created by tectonic activity promotes a continuous supply of uranium- and oxygen-bearing fluids to the uranium reservoirs, resulting in a multi-energy coupling mineralization effect. Full article

To achieve a significant breakthrough in the exploration of uranium resources in the Guangzitian area of northern Guangxi, China, an innovative combination of exploration methods was implemented at the peripheral regions of the Guangzitian uranium deposit under the guidance of the following principle: “exploring the edges and identifying the bottom, delving deep and un-covering blind spots”. This study introduces geo-electrochemical integrated technology for prospecting research at the peripheral areas of the Guangzitian deposit. By validating the technology’s effectiveness on known geological sections, distinct geo-electrochemical extraction anomalies were identified above recognized ore bodies. Simultaneously, soil ionic conductivity and thermally released mercury anomalies were observed, partially indicating the presence of concealed uranium deposits and fault structures. These findings demonstrate that geo-electrochemical integrated technology is effective in detecting buried uranium mineralization in this region. Subsequently, a geological-geoelectrical prospecting model was established through a systematic analysis of anomaly characteristics and metallogenic regularity, and it was subsequently applied to unexplored areas. As a result, one key anomaly verification zone, one Class A comprehensive anomaly zone, two Class B comprehensive anomaly zones, and one Class C comprehensive anomaly zone were identified within the unexplored research area. Drilling engineering validation was conducted in the No. Ι key anomaly verification zone, resulting in the discovery of an industrial-grade uranium ore body. This achievement not only provides critical technical support but also develops a robust theoretical foundation for future mineral exploration endeavors. Full article

Carbonaceous–siliceous–argillaceous rock-type uranium deposits, a major uranium resource in China, pose significant environmental risks due to heavy metal contamination. Geochemical investigations in the former Zoige uranium mine revealed elevated As, Cd, Cr, Cu, Ni, U, and Zn concentrations in soils and sediments, particularly at river confluences and downstream regions, attributed to leachate migration from ore bodies and tailings ponds. Surface samples exhibited high Cd bioavailability. The integrated BCR and mineral analysis reveals that Acid-soluble and reducible fractions of Ni, Cu, Zn, As, and Pb are governed by carbonate dissolution and Fe-Mn oxide dynamics via silicate weathering, while residual and oxidizable fractions show weak mineral-phase dependencies. Positive Matrix Factorization identified natural lithogenic, anthropogenic–natural composite, mining-related sources. Pollution assessments using geo-accumulation index and contamination factor demonstrated severe contamination disparities: soils showed extreme Cd pollution, moderate U, As, Zn contamination, and no Cr, Pb pollution (overall moderate risk); sediments exhibited extreme Cd pollution, moderate Ni, Zn, U levels, and negligible Cr, Pb impacts (overall extreme risk). USEPA health risk models indicated notable non-carcinogenic (higher in adults) and carcinogenic risks (higher in children) for both age groups. Ecological risk assessments categorized As, Cr, Cu, Ni, Pb, and Zn as low risk, contrasting with Cd (extremely high risk) and sediment-bound U (high risk). These findings underscore mining legacy as a critical environmental stressor and highlight the necessity for multi-source pollution mitigation strategies. Full article

The characteristics of interlayer oxidation zones constrain sandstone-type uranium mineralization. This study conducted a quantitative characterization of the interlayer oxidation zones in the uranium-bearing reservoir of the Saihan Formation in the central Wulanchabu Subbasin of the Erlian Basin through sand dispersion system mapping, the analysis of sedimentary debris components, environmentally sensitive parameters, and elemental geochemical characteristics. The formation mechanisms and controlling factors of interlayer oxidation zones were investigated, along with uranium mineralization patterns. Research findings reveal that the sandbodies in the study area primarily consist of red sandstone, yellow sandstone, gray ore-bearing sandstone, and primary gray sandstone, representing strong oxidation zones, weak oxidation zones, transitional zones, and reduction zones, respectively. Although the mineral debris content shows minimal variation among different zones, feldspar dissolution is more prevalent in oxidized zones. During interlayer oxidation, environmentally sensitive parameters exhibit an ascending trend from strong oxidation zones through weak oxidation zones and reduction zones to mineralized transitional zones. Four transition metal elements (Co, Ni, Zn, and Mo) demonstrate enrichment in mineralized transitional zones. The development of interlayer oxidation zones is directly controlled by reservoir heterogeneity and sedimentary environments. Oxidation subzones primarily occur in sandbodies with moderate thickness (40–80 m), sand content ratios of 40%–80%, and 2–10 or 10–18 mudstone barriers (approximately 20 m thick), mainly in braided river channels and channel margin deposits. Reduction zones develop in thicker sandbodies (~100 m) with higher sand contents (~80%), fewer mudstone barriers (2–8 layers), greater thickness (40–80 m), and predominantly channel margin deposits. Transitional zones mainly occur in braided distributary channels and floodplain deposits. When oxygen-bearing uranium fluids infiltrate reservoirs, oxygen reacts with reductants like organic matter, whereFe²⁺ oxidizes to Fe³⁺, S²⁻ reacts with oxygen, and U⁴⁺ oxidizes to U⁶⁺, migrating as uranyl complexes. As oxygen depletes, Fe³⁺ reduces to Fe²⁺, combining with S²⁻ to form pyrite between mineral grains. Uranyl complexes reduce to precipitate as pitchblende, while some U⁴⁺ reacts with SiO₄⁴⁻, forming coffinite, occurring as colloids around quartz debris or pyrite. The concurrent enrichment of certain transition metal elements occurs during this process. Full article

The drilling core sampling and chemical analysis method for the quantitative determination of solid mineral deposits has several drawbacks, including a low core drilling efficiency, a high core sampling cost, and a long chemical analysis cycle. In current uranium quantification practices, advanced techniques have been developed to preliminarily determine the formation of uranium content based on the interpretation results of natural $\gamma$-ray total logging. However, such methods still require supplementary core chemical analysis to derive the uranium–radium–radon balance coefficient, which is then used for equilibrium correction to obtain the true uranium content within the uranium-bearing layer. Furthermore, conventional prompt neutron time spectrum logging is constrained by low count rates, resulting in slow logging speeds that fail to meet the demands of practical engineering applications. To address this, this study proposes a uranium quantification method that corrects the natural $\gamma$-ray total logging using prompt neutron time spectrum logging. Additionally, a calibration parameter determination method necessary for quantitative interpretation is constructed. Experimental results from standardized model wells indicate that, in sandstone-type uranium deposits, the absolute error of uranium content is within $\pm 0.002\%\mathrm{eU}$, and the relative error is within $\pm 2.5\%$. These findings validate the feasibility of deriving the uranium–radium–radon balance coefficient without relying on core chemical analysis. Compared with the prompt neutron time spectrum logging method, the proposed approach significantly improves the logging speed while producing results that are essentially consistent with those of natural $\gamma$-ray total logging. It provides an efficient and accurate solution for uranium quantitative interpretation. Full article

Using pitchblende uranium ore GBW04420 as the standard material and through the secondary ion mass spectrometry (SIMS) technical method, the in situ U-Pb isotopic chronology characteristics of the main granite-type uranium deposits in the Xiazhuang ore field in the Nanling area of southern China were studied. Firstly, the suitability of GBW04420 as the in situ U-Pb isotopic dating standard material for uranium minerals was verified. On this basis, the in situ U-Pb isotopic ages of the three main granite-type uranium deposits in the Xiazhuang ore field, namely the Xianshi, Zhaixia, and Xiwang deposits, were obtained by SIMS dating. The results show that the overall mineralization period of the Xiazhuang ore field is mainly in Late Cretaceous and the Eocene-Oligocene. The mineralization ages indicate that the uranium deposits are of post-magmatic, medium-low temperature hydrothermal origin rather than the magmatic uranium deposit type. The hydrothermal fluids originate from the combined effect of the crust-mantle hydrothermal fluid and atmospheric precipitation; the uranium source originates from the extraction of the Indosinian-Early Yanshanian diagenetic granite by atmospheric water and partly from the mantle source of the basic dike. Full article

A combination of microstructural, fluid inclusion, and in situ sulfur isotopic analyses of pyrite, along with major and trace element studies of the mineralization-hosting sandstone, reveals the complexity of its genesis from the Jurassic Toutunhe Formation in the Liuhuanggou sandstone-hosted uranium deposit, Southern Junggar Basin. Based on field geological investigations and the geochemical characteristics, it is concluded that the source of the ore-bearing sandstones originates from felsic igneous rocks in the Northern Tianshan and Central Tianshan regions. Through optical microscopy and scanning electron microscopy (SEM), three generations of pyrite were identified: framboidal pyrite, concentric overgrown pyrite, and sub-idiomorphic to idiomorphic cement pyrite. The sulfur isotopes of the pyrite were analyzed using laser ablation multi-collector inductively coupled plasma mass spectrometry (LA-MC-ICP-MS). The results indicate that each type of pyrite has distinct sulfur isotope compositions (the framboidal pyrite: −16.85‰ to +2.16‰, the concentric overgrown pyrite: −7.86‰ to +10.32‰, the sub-idiomorphic to idiomorphic cement pyrite: +9.16‰ to +16.77‰). The framboidal pyrite and the sub-idiomorphic to idiomorphic cement pyrite were formed through bacterial sulfate reduction (BSR), while the concentric overgrown pyrite was formed through thermochemical sulfate reduction (TSR) triggered by the upward migration of hydrocarbons. The discovery of hydrocarbon inclusions provides evidence for the involvement of deep-seated reducing fluids in uranium mineralization. Uranium mineralization occurred in two distinct stages: (1) The early stage involved the interaction of uranium-bearing fluids with reductants in the mineralization-hosting strata under the influence of groundwater dynamics, leading to initial uranium enrichment. (2) The later stage involved the upward migration of deep-seated hydrocarbons along faults, which enhanced the reducing capacity of the sandstone and resulted in further uranium enrichment and mineralization. Full article

The Mamuju region in West Sulawesi, Indonesia, is a High Background Natural Radiation Area (HBNRA) characterized by a significant enrichment of high field strength elements (HFSEs) and rare earth elements (REEs) within its lateritic deposits. This study investigates the geochemical behavior, mineralogical distribution, and enrichment processes of HFSEs and REEs in lateritic profiles of drill cores and surface samples derived from alkaline volcanic rocks. The mineralogy and geochemical content of HFSEs and REEs in the alkaline bedrocks indicate its potential to become a source of lateritic enrichment. An intense lateritic weathering process leads to the residual accumulation of HFSEs and REEs, particularly in B-horizon soils, where clay minerals and Fe–Al oxides are crucial in element precipitation. Moreover, groundwater redox conditions are a key factor for uranium precipitation in the lateritic profile. The findings provide insight into the potential of lateritic weathering as a natural mechanism for HFSE and REE concentration, contributing to the broader understanding of critical metal resources in Indonesia. These insights have implications for sustainable resource exploration and environmental management in areas with high natural radiation exposure. Full article

Progress in the exploration of uranium deposits in the Qinling region is impacted by a number of factors, including extensive forest distribution, large-scale terrain segmentation, and hidden ore bodies. Airborne gamma-ray spectrometry measurement is a direct method for uranium exploration, with data containing rich uranium mineralization information. In addition to surface mineralization information, such measurements also contain some information on deep uranium mineralization. Based on the geological characteristics of a specific area in the Qinling region, conventional data processing methods of airborne gamma-ray spectrometry (such as total elemental content, uranium, potassium and thorium content, and elemental ratios), the overall spectral characteristics obtained were analyzed. By utilizing the geochemical differences among K, U, and Th element contents, a model of four multi-element combination parameters of airborne gamma-ray spectrometry was constructed, including ancient uranium content, uranium activation migration coefficient, uranium abundance degree coefficient, and uranium migration enrichment coefficient, together with their geological significance. The model enhances the weak anomaly information of airborne gamma-ray spectrometry and provides a detailed analysis of key areas within the study area. Lastly, based on the extraction of multi-element anomaly information from airborne gamma-ray spectrometry data and optimal selection, combined with favorable geological information for exploration, a method for rapidly delineating prospective uranium ore areas is proposed, with three uranium ore prospective areas being predicted within the study area. Full article

In the late 1960s, a uranium province was explored in the Shu-Sarysu depression in southern Kazakhstan. These mining operations can lead to potential contamination of the environment and pose health risks to the population. The aim of this study is to carry out environmental monitoring in uranium deposits and assess indoor radon levels in settlements located in the uranium mining area in the southern region of Kazakhstan. Elevated outdoor ambient equivalent dose rates (0.5–1.2 µSv/h) were detected beyond the buffer zone, particularly near a preserved self-flowing well, where the highest activity concentrations of natural radionuclides were recorded (²²⁶Ra—2350 Bq/kg, ²³²Th—270 Bq/kg, ⁴⁰K—860 Bq/kg), exceeding background levels. Indoor ambient equivalent dose rates in the settlements of Taukent, Zhuantobe, Tasty, and Shu ranged from 0.04 to 0.15 μSv/h, while outdoor levels varied from 0.03 to 0.1 μSv/h, remaining within global and regional average values. Radon concentrations were highest in Tasty and Shu but did not exceed the permissible level. However, Shu exhibited the highest radiation exposure dose (>4 mSv/y), approaching the lower range of recommended action levels (3–10 mSv/y). These findings highlight the necessity for continuous monitoring and potential mitigation strategies in areas with naturally elevated radiation levels. Full article

Lithological mapping using satellite images, particularly hyperspectral data, helps in effectively defining the best initial targets for regional exploration. In this study, ZY1-02D hyperspectral image (HSI) data with moderate spectral and very high spatial resolution were employed for lithological mapping using spectral indices along with support vector machine (SVM) machine learning and spatial–spectral transformer (SSTF) deep learning methods in the Kohat–Pothohar Plateau at the eastern edge of the Main Boundary Thrust (MBT) in Pakistan. The research was accomplished using spectral profiles of minerals accompanied by false color composite (FCC), principal component analysis (PCA), SVM, and SSTF methods for classifying the main lithological units. The lithological discrimination map derived from the ZY1-02D data matched well with the known deposits and field inspections. The principal component analysis (PCA) obtained the highest eigenvalues and provided a significant discrimination of lithologies, particularly with hyperspectral data. The results revealed lithological units, three of which contained limestone and gypsum, while other lithological units were defined as sandstone, clay, and conglomerates. Field investigation and laboratory sample analysis through X-ray diffraction (XRD), photomicrographs, and spectral analysis confirmed the occurrence of limestone, gypsum, and sandstone, which are useful in identifying lithological units in the study area. This study will assist in more accurate geological discrimination and play a vital role in identifying oil and gas reservoirs, coal, gypsum, uranium, salt, and limestone deposits. Furthermore, the results of the SVM and SSTF techniques were quantitatively compared with the geological boundaries mapped in the field, showing an accuracy of nearly 89.7% and 92.1%, respectively. Overall, the methodology adopted showed great performance and strong potential for mapping alteration areas and lithological discriminations applied on the ZY1-02D hyperspectral data. Full article