Uranium Deposits Research Articles

Mineralization process of the Changjiang uranium orefield in South China: Constraints from pitchblende geochemistry

The Changjiang uranium (U) orefield in northern Guangdong (South China) contains several important granite-related uranium deposits, including the Mianhuakeng deposit. The hydrothermal evolution and mineralization mechanism of the deposit remain unclear, and hence in this study we analyzed the mineral compositional variations of pitchblende from different elevation (−300 to −50 m) in the orebody at Mianhuakeng deposit. The results indicate that with decreasing depth, the hydrothermal mineral assemblage changes from a reducing one (pitchblende, pyrite, and chlorite) to a moderately oxidizing one (pitchblende, coffinite, hematite, and goethite). The contents of U, Sr, ∑REE, U/Th, and LREE/HREE ratios in the pitchblende decrease (whereas the Cu-Pb-Zn-Ni-Co-Sc-Rb contents increase) progressively with decreasing depth. Also, Ce anomaly (Ce/Ce*) changes from positive to negative, and Eu anomaly (Eu/Eu*) becomes more negative with decreasing depth. We interpreted such vertical variations to be caused by the ascent of deep, mid-to-high temperature, highly-oxidizing ore-forming fluid, which was reduced by early-stage reducing minerals in the wallrock, a process that also formed the mineralization at Changjiang. In addition, the pitchblende REE distribution patterns and Eu/Eu* at depth (−300 m) resemble those of the Zhuguang pluton, indicating that the ore-forming materials were originated from the U-bearing granite wallrocks. Therefore, the Ce/Ce* and Eu/Eu* variations of pitchblende can be used to guide deep uranium ore exploration.

Tl, Mo and U isotopes in U-ore deposits record Earth's fundamental redox processes

Understanding changes in redox conditions in the Earth's geological record is fundamental to unravelling some of the major events of our planet's history, such as the Great Oxidation Event (G.O.E.), biological changes through time related to mass extinctions, or the formation of ore deposits for primordial metal resources. Rocks from uranium deposits are ideal candidates to examine the coupled isotopic fractionation of Tl, Mo and U, as they are fundamentally caused by redox processes, occur in a wide variety of geological settings throughout much of geological history (from about 3 Ga), and result from the interplay between fluids and rocks of variable redox states. Herein we measure δ97Mo (−10.2 to +6.1 ‰), ε205Tl (−9.5 to +5.0 ε-units), and δ238U (−0.72 to 0.30 ‰) for 34 samples from granite-related, intrusive, metamorphic, and Proterozoic unconformity related U deposits. Collectively, these results suggest: 1) in metamorphic and unconformity-related contexts, samples with decreasing ε205Tl values also have decreasing δ238U values, indicative of change in redox conditions, 2) ε205Tl values in the sulfide-rich samples likely reflect the affinity of 205Tl for these minerals, 3) Tl undergoes significant isotopic fractionation during the reduction of U-bearing fluids to precipitate uraninite, and 4) Tl isotopes do not fractionate during secondary remobilization of elements within these systems, and thus retain a record of the conditions of formation, whereas Mo isotopes are heavily fractionated by secondary remobilization. We suggest that the study of U, Mo, and Tl isotopes in U-ore deposits conveys new information related to building blocks of life on Earth and shows great potential for the study of past oxygenation events, thus potentially allowing us to reconstruct the geological and chemical history of our planet.

Sedimentary Environment, Tectonic Setting, and Uranium Mineralization Implications of the Yimin Formation, Kelulun Depression, Hailar Basin, China

The sandstone-type uranium deposit of the Kelulun Depression is the first industrially valuable uranium deposit discovered in the Hailar Basin. This study performed a systematic examination of 17 sandstone samples from the Yimin Formation in the Kelulun Depression based on various analytical techniques. The findings of the current study were synthesized with previous research to investigate the impact of the redox conditions and the tectonic background of the source area, as well as the paleoclimatic evolution of the Yimin Formation on uranium mineralization. The elemental Mo, U/Th, V/Cr, Ni/Co, and V/(V+Ni) ratios indicate that the paleowater was in an oxygen-rich environment during the deposition of the Yimin Formation. Additionally, the C-value, Sr/Cu, Al2O3/MgO, and Rb/Sr ratios indicate that the Yimin Formation was formed in a paleoclimate characterized by arid-to-semi-arid conditions. The geochemical characteristics of the observed elements indicated that the sediment source of the Yimin Formation was mainly felsic rocks from the upper continental crust, the weathering of the rock was weak, and the tectonic background was a passive continental margin. Coffinite is distributed in the form of cementation and stellates within or around pyrite crystals, and uranium-titanium oxide is mostly distributed in an irregular granular distribution in the biotite cleavage fractures of the study area. In summary, the findings of this study reveal that the tectonic settings, provenance, uranium source, paleoclimate, and oxygen-rich paleowater of the Yimin Formation have important geological significance for the large-scale uranium mineralization of the Kelulun Depression.

Characterization and concentration of U, Nb, Pb, Ag, and Fe from the Huayangchuan polymetallic ore

The separation and recovery of valuable metals from the Huayangchuan uranium polymetallic ore was investigated based on mineralogical research and mineral processing experiments. The most promising valuable elements in the ore, according to mineralogical studies, are U, Nb, and Pb. 95.75% of U and 93.00% of Nb are found in betafite, 46.85% of Pb is present in galena, 52.01% of Pb occurs in cerussite, and associated Ag exists primarily in galena. The beneficiation process involving gravity concentration, magnetic separation, and flotation was determined based on the mineralogical characteristics of the ore. The U-Nb concentrate with U grade of 3578 ppm and recovery of 83.18 %, Nb<sub>2</sub>O<sub>5</sub> grade of 4391 ppm and recovery of 74.55 % can be obtained, and five elements including U, Nb, Pb, Ag, and Fe are recovered. Compared with the previous beneficiation experimental process, the flowsheet is greatly simplified and the beneficiation recovery efficiency has been improved. The results of this investigation can help to address the gaps in the processing of low-grade uranium deposits with similar mineralogical properties.

Identification of the Sedimentary Sources and Origin of Uranium for Zhiluo Formation of the Tarangaole U Deposit, Northeastern Ordos Basin

The large-sized Tarangaole uranium deposit and its neighboring Daying and Nalinggou deposits, located in the northeastern margin of the Ordos Basin, constitutes a major uranium resource base in northern China. In order to further clarify the sedimentary material source, uranium source and regional sediment–tectonic setting of the uranium-fed clastic rocks (i.e., Zhiluo Formation(J2z)) in the district, this paper carried out whole-rock geochemistry, heavy minerals composition and in situ U-Pb dating of detrital zircons for sandstones from the lower section of the Zhiluo Formation. The results have shown that the average chemical differentiation index (CIA) for the host rocks is 73.16 and the chemical weathering degree is moderate. Heavy minerals are mainly composed of ilmenite, garnet, chlorpyrite, zircon, pyrite, apatite, hematite, etc. The U-Pb dating of detrital zircon generally indicates three age peaks, i.e., 260~Ma, 1850~Ma and 2450~Ma, respectively. In conclusion, the source rocks may have been formed at active continental margins, e.g., in a continental margin arc environment. The sedimentary materials mainly come from khondalite series, TTGs, granulite, and mafic–ultramafic intrusive rocks distributed among the Daqing–Ula Mountains and adjacent areas, etc. The Late Paleozoic U-rich intermediate and acidic magmatic rocks spreading over the eastern part of the Ula–Daqing and Wolf mountains have provided the main uranium sources for the formation of major U deposits in the northern Ordos Basin.

Genesis of gray sandstone within the red beds in HLJ-DL uranium deposit, southwest Songliao Basin and its relationship with uranium mineralization

The search for uranium deposits in the red beds is currently a hotspot in China's sandstone-type uranium exploration efforts. The typical occurrence of uranium deposits is within gray sandstone layers amidst the red beds, where the distribution of these gray sand bodies dictates the presence of uranium deposits. Hence, delving into the genesis of gray sandstone within the red beds proves beneficial for both uranium exploration and unraveling the ore-forming mechanisms. However, there is currently significant controversy surrounding the genesis of gray sandstone in the red beds. This paper focuses on the typical uranium deposit in the red beds—the HLJ-DL uranium deposit in the southwestern part of the Songliao Basin. It investigates the genesis of gray sandstone within uranium-bearing rock series and its relationship with uranium mineralization. The lithology of representative drill cores, including the red sandstone for comparative study, is methodically examined, along with their elemental geochemistry as well as carbon and oxygen isotope characteristics. The petrological characteristics suggest that both the gray and red sandstone share similar compositions of clastic particles, indicating minimal influence of the source rock on the sandstone color. The gray sandstone displays comparable TOC content (averaging around 0.05 %) and δ18OPDB values (averaging around −16 ‰) to the red sandstone. However, it exhibits relatively higher δ13CPDB values (averaging −0.26 ‰), whereas the average δ13CPDB value for the red beds is −1.61 ‰. The data indicate that the gray sandstone is less affected by hydrothermal or hydrocarbon fluids. Compared to the red sandstone, which has relatively higher Cu/Al values (averaging 1.09) and Fe3+/Fe2+ ratios (averaging 3.37), the gray sandstone exhibits low Cu/Al values (averaging 0.44) and a low Fe3+/Fe2+ ratio (averaging 0.36), suggesting its formation in a relatively reducing environment. The reducing conditions necessary for the formation of gray sandstone may stem from the climate becoming relatively warm and humid, irrespective of whether it originates from the original sedimentary environment or is induced by the reducing pore water discharged from dark mudstones. The chemical weathering index of fine-grained sediments indicates that, the gray sandstones were commonly configured in relatively humid-warm climate with fairly low dissolved oxygen content in the bottom water. Additionally, the deposition of the uranium-bearing rock series experienced alternating climatic changes, rather than consistently being in a humid-warm climate. This resulted in the sand bodies with low TOC content, insufficient reducing potential, and uranium mineralization primarily occurring in the interior of the basin. Organic matter has a relatively weak control over uranium mineralization, whereas uranium mineralization shows a certain correlation with iron reduction. The ore-forming fluid was uranium-rich oxygenated atmospheric water. Dark-colored mudstones, formed under humid-warm climatic condition, contain relatively high TOC contents (avg. 0.43 %) and exhibit a strong reducing capacity. The reducing pore water in dark-colored mudstones excreted into the adjacent sandstones under compaction during the early diagenesis, is able to serve as a vital reducing agent in later-stage uranium mineralization. Additionally, certain dark-colored mudstones with high uranium content (up to 944 ppm) undergo significant uranium pre-enrichment, providing a partial uranium source for uranium mineralization.

Jurassic sedimentary evolution model and its implication for the sandstone-type uranium mineralization in the Kamusite area in eastern Junggar Basin, NW China

The Junggar Basin in the northern Xinjiang Province, northwestern China, is a large hydrocarbon basin with tremendous reserves of oil, gas and coals. Tens of sandstone-type uranium showings, occurrences and/or anomalies have also been discovered in the Junggar Basin since the 1960s, yet hitherto only one large uranium deposit, the Kamusite deposit, has been identified in the Middle Jurassic Toutunhe Formation sandstones in the eastern part of the basin. Sand bodies with high-permeability are the prerequisite for the formation of the in situ leachable sandstone-hosted uranium deposit, nevertheless the spatial distribution and genetic types of the sand bodies, as well as the deposition model in Jurassic time in the Kamusite area both remain unclear, which largely hindered the understanding of the sedimentary evolution and uranium exploration directions in the region.In this contribution, based on the outcrop observation, core logging and well logging data interpretation, and comprehensive analysis, the sedimentary characteristics, sedimentary facies types, sand body morphology, plane distribution characteristics, as well as the sedimentary evolution history in Jurassic time in the Kamusite area have been illustrated in details. From early to late, the Jurassic sediments in Kamusite can be divided into the Badaowan, Sangonghe, Xishanyao, Toutunhe and Qigu formations, of which the sand bodies favorable for the sandstone-type uranium mineralization have been systematically analyzed, and the depositional model in the Kamusite area have been established. The Early Jurassic Badaowan Formation is a set of coal-bearing coarse-grained clastic sediments of the braided river–braided river delta facies, followed by the lake transgression and fine-grained lacustrine deposition in the Sangonghe Formation. The Middle Jurassic Xishanyao Formation is a set of braided river delta facies coal-bearing clastic sediments, while the uranium orebody-bearing Toutunhe Formation underwent the paleoclimate transition from warm and humid to hot and arid, and developed a set of braided river delta to meandering river facies sequences with an overall positive sedimentary rhythm. The Qigu Formation is dominated by a series of meandering river to lacustrine facies fine-grained sediments and largely denuded by later tectonic activities. Three sets of sand bodies favorable for the sandstone-type uranium mineralization are recognized, including those in the lower Toutunhe Formation, the lower Xishanyao Formation, and the upper Badaowan Formation, from bottom to top. A four-stage sedimentary evolution model from the Badaowan Formation to the Toutunhe Formation has been established thereafter, and general exploration suggestions were proposed in the last of the contribution. More drilling is recommended to the south of the Kalasayi Fault, aiming the lower Toutunhe, lower Xishanyao and upper Badaowan formations. To the north of the Kalasayi Fault, more uranium mineralization could also be expected, and the exploration is suggested to focus on the Jurassic Toutunhe, Xishanyao formations and Cretaceous Tugulu Group.

State of the surface waters in the Mesta River basin, after the reclamation of the Eleshnitsa uranium deposit

In the period from 1955 to 1992, uranium ore was mined and processed in the Mesta River basin around the village of Eleshnitsa, region of Razlog. The ore processing plant was built and a tailings storage facility was built next to it. In the period 2002–2006, the tailings storage was reclaimed, and in 2011–2012 the ore mines were also reclaimed. For the treatment of drainage water, a treatment plant was built in the valley of Valchoto Dere River, a left tributary of the Mesta River. The radiological monitoring carried out by the Basin Directorate “West Aegean Sea Region” reveals a generally good quality of the surface waters in terms of the content of uranium and radium (226Ra) outside the area of the former uranium mining and the tailings storage facility. In this area, in some years a high content of natural uranium was found, with concentrations from 0.54 to 67.40 mg/l on average per year. The values significantly exceed (by 1.8 to 224.6 times) the norm regulated in the regulation for radiation protection and safety from the liquidation of the consequences of uranium mining. The spread of uranium is limited to a small area shortly downstream from the sources of contamination, but the potential risk to the local ecosystem should not be neglected. Radium, in contrast to uranium, has concentrations below the permissible limits in the twelve years studied. Its content varied from 0.025 to 0.11 Bq/l on average annually. The results show that the Mesta River near the border with the Republic of Greece is not contaminated with the studied radionuclides.

The Influence of the Physicochemical Characteristics of Ores on the Efficiency of Underground Well Leaching of Uranium Deposits in Kazakhstan

The features of uranium mining on Kazakhstan’s enterprises have been examined, and uranium deposits located in the Syrdarya and Shu-Sarysu depressions have been described. Actual and projected data on the development of technological blocks in areas with complex geological structures have been analyzed and compared. Core samples were collected and, using X-ray diffraction analysis, quantitative and qualitative characteristics as well as mineral compositions of ores from various productive horizons of uranium deposits in the Syrdarya and Shu-Sarysu depressions were comparatively analyzed. It was determined that the ores in the Syrdarya depression are relatively homogeneous compared to those in the Shu-Sarysu depression, although in some places, clay minerals and gypsum are present, which hinder the uranium leaching processes. In the ores of the Shu-Sarysu depression, clay minerals that impede the uranium leaching processes are present in certain areas. Microscopic analysis of core material samples using a LEICA DM 2500 P microscope revealed particle sizes and shapes, as well as their distribution within the structure of host rocks in the productive horizon. Using X-ray diffraction analysis, mineral compositions of sediment-forming components during uranium well mining in the considered productive horizons were determined and comparatively analyzed. It was established that in the geotechnological wells of the Syrdarya depression, sediments of predominantly chemical origin, such as gypsum, are formed. However, in the geotechnological wells of the Shu-Sarysu depression, sediments of mechanical origin, consisting predominantly of quartz particles and clay minerals, are formed. Based on the obtained data, a method for intensifying underground uranium leaching in complex geological conditions has been developed, which involves dissolving sediment formations and increasing the oxidative–reductive potential of the leaching solution. The proposed and experimentally substantiated universal methodology for enhancing uranium well production involves the dissolution and prevention of precipitation using hydrofluoric acid solutions, as well as the oxidation of uranium dioxide with hydrogen peroxide.

Mineralogical and geochemical studies on the Qianjiadian deposit, Songliao Basin, NE China: Insights into multiple metallogenic processes in the sandstone-type uranium deposit

Sandstone-type uranium deposits usually exhibit a range of metallogenic mechanisms. To gain insights into the nature, genetic relationships, and mineralization mechanisms of uranium and associated minerals, representative samples from the Qianjiadian uranium deposit in the Songliao Basin were investigated through detailed mineralogical, elemental geochemical, and in-situ sulfur isotopic analyses. The results provided invaluable information on the various stages of uranium mineralization. During the early diagenetic stage, uranium mineralization occurred in the local organic matter (OM)-enriched sites (TOC = 0.70 ∼ 2.05 %) in the Yaojia Formation. The paragenetic relationship revealed that uranium was firstly precipitated as pitchblende along with the biogenetic framboidal pyrite (δ34S values ranging from −44.1 ‰ to −1.8 ‰) through bacterial sulfate reduction (BSR) process. Simultaneously, organic acids generated through biodegradation of OM caused an acidic fluid condition and subsequent dissolution of feldspars, resulting in the production of kaolinite intergrowth with pitchblende. During the late diagenetic stage, the ore-forming fluid turned alkaline, leading to the conversion of pitchblende into coffinite, with elevated elements such as Si, P, Ca, Zr, and Y in the altered phase. In addition to the contribution of OM and sulfate-reducing bacteria (SRB), pyrite was confirmed as a reducing agent for its replacement by uranium minerals and the Fe-oxide produced along the boundaries. The diagenetic uranium enrichment is mainly hosted in the gray sandstone that experienced reduced alteration of deep hydrocarbons, resulting in pervasive kaolinization and promotion of reduction potential. A significant amount of uranium was fixed by adsorption, as evidenced by the rare observation of independent uranium minerals, but the higher whole-rock U content (U = 133.5 ∼ 394.0 ppm) and the detection of U signal in micro-XRF analysis and EPMA data (U content in representative kaolinite ranges from bld to 0.74 wt%). Overall, the formation of sandstone-type uranium deposits is a long-term and multi-stage process. The early enriched uranium during synsedimentary-diagenetic stages is non-negligible and can even result in an appreciable amount of mineralization, further serving as an important source for the subsequent secondary enrichment.

Fluid Migration Regimes during the Formation of the Unconformity-Related Uranium Deposits of the Alligator Rivers Uranium Field, Australia

Fluid Migration Regimes during the Formation of the Unconformity-Related Uranium Deposits of the Alligator Rivers Uranium Field, Australia

Polymorphic transformations of titanium oxides contribute to economic uranium mineralization in sandstone

Sandstone-hosted uranium (U) deposits provide a significant U resource for nuclear energy worldwide. Driven by redox reactions, tetravalent uranium-bearing minerals are commonly associated with reductants (e.g., pyrite and organic matter). However, numerous observations have revealed that tetravalent uranium-bearing minerals can spatially coexist with chemically stabilized titanium oxides in sandstone-hosted U deposits, requiring a complementary mechanism to interpret these findings. We present a new model based on in situ texture, trace-element content, and titanium isotopic ratio, as well as polymorph type and related transformation for titanium oxides from the Yaojia Formation of the southwestern Songliao Basin in northeast China. Specifically, in our model, abundant nanopores were generated during the spontaneous transformation of anatase to rutile, producing a porous material for hexavalent U adsorption. Facilitated by a U-rich source rock, adsorbed U in porous titanium oxide from the lower Yaojia Formation was up to several thousand parts per million. In order to minimize surface energy, a subsequent decrease in surface area by merging small pores is inevitable. When the evolved surface area was small enough, hexavalent U would be desorbed and subsequently transformed to tetravalent U by local reductants, forming uraninite nanoparticles on the surface of U-rich rutile with relatively large pores. Our newly proposed mechanism not only contributes to a better understanding of economic U mineralization in sandstone, but also suggests that U occurred as uranium oxide instead of brannerite in sandstone-hosted U deposits, providing a nano-mineralogical perspective required for industrial processing.

Genesis of the Haidewula volcanic rock-hosted uranium deposit in the East Kunlun Orogen, northwestern China

The Haidewula deposit in Northwest China is a recently discovered volcanic-related uranium deposit. To determine the origin of this deposit, whole-rock geochemical, stable isotope, U–Pb isotope and trace element compositions of the pitchblende were obtained, and microthermometric analyses of the fluid inclusions were performed. The Haidewula deposit is located within the Phanerozoic volcanic basin and contains Silurian trachyte, rhyolite, rhyolitic tuff, and Triassic basalt. These Silurian volcanic rocks are characterized by high-K calc-alkaline properties and were intruded by Triassic dolerite, which served as a source for mineralization. The mineralized zones were primarily influenced by NE-NNE-trending and SE-dipping faults. Vein-like pitchblende is commonly associated with calcite, illite, quartz, pyrite, and fluorite. Geochronology indicated that uranium mineralization occurred during 235–230 Ma. The ore-forming fluids contained meteoric water with limited magmatic water and exhibited moderate to low temperatures (246–133 °C), moderate to low salinities (17.3–1.06 wt% NaCleqv) and Cl-bearing rocks. U precipitation was attributed to changes in physicochemical conditions resulting from fluid–rock interactions and fluid boiling. The uranium mineralization at Haidewula coincided with the evolution of the Tethys Ocean. During late Wenlock, an extensional environment, triggered by the closure of the Proto-Tethys Ocean, led to the extrusion of Haidewula rhyolite and trachyte. During the crustal extensional environment resulting from the subduction of the A’nyemaqen Ocean in the Middle Triassic, ore-forming fluids circulated and remobilized uranium from the Haidewula volcanic rocks. As a result of fluid–rock interactions and fluid boiling within brittle structures, the U-complexes destabilized and formed pitchblende at Haidewula.

Geology and geochronology of the Yingqian granite-type uranium deposit in the Taoshan-Zhuguang Belt, South China

The Yingqian uranium deposit in the Taoshan-Zhuguang belt, South China is a typical granite-type uranium deposit. The geological characteristics and timing of mineralization are not clear, which hinders the understanding of the ore genesis of the Yingqian deposit as well as regional uranium metallogeny in the Taoshan-Zhuguang belt. These scientific problems are examined in this study through detailed field work and petrographic study, as well as geochemical and geochronological analyses on apatite, rutile and zircon. The orebodies of the Yingqian uranium deposit are mostly present in the medium–coarse grained biotite granite and fine grained two-mica granite, and controlled by the NE-trending faults. The principle U-bearing minerals are pitchblende and brannerite, with the presence of metal minerals like pyrite, hematite and minor galena and sphalerite. The predominant hydrothermal alterations are hematitization, fluoritization, illitization, silicification, chloritization and carbonatization. Gangue minerals are mainly quartz, fluorite, illite and calcite. Moreover, four hydrothermal stages can be recognized in the Yingqian deposit, and the second and third stages are the uraniferous ones. The alterations and mineral assemblages indicate ore fluids are acidic, oxidized, and rich in F, P, CO2, which is favorable for dissolving uranium. Abundant apatite and rutile are discovered in the uraniferous third-stage veins. Geochemical analyses indicate that rutile is plotted in the hydrothermal area in the Ti-100 (Fe + Cr + V)-1000 (W) ternary diagram, and apatite is classified as fluorapatite. In-situ LA-ICP-MS dating indicates that the ore-hosting medium–coarse grained biotite granite and fine grained two-mica granite obtain the zircon U-Pb ages of 160.0 ± 0.3 Ma and 164.1 ± 0.6 Ma, which are consistent with many Jurassic granites in the South China Block. The hydrothermal apatite and rutile yield the U-Pb ages of 96.4 ± 11.6 Ma and 85.6 ± 10.8 Ma, respectively, indicating that uranium mineralization is significantly younger than the ore-hosting granites and generally coeval with the regional mafic magmatism. Consequently, the uraniferous fluids in the Yingqian deposit are independent from the magmatic system. Combined with previous research, it is concluded that fluid convection promoted by mantle–crust interaction would leach uranium from various lithologies, and fluid-rock interactions, fluid boiling and cooling are the causes for uranium precipitation.

Role of zeolite content on the sorption properties of analcime-rich rocks from the Abinky Formation (Niger)

The Abinky formation, composed of analcimolites (i.e., rocks with <70 wt% analcime), underlies Tchirezrine II, which hosts the Imouraren (Niger) uranium deposit. A potential mining project is under consideration to recover U by in situ acid leaching. Analcimolites are uncommon rocks, and assessing their ion-exchange properties is the first step to understand and predict the mobility of aqueous species in these formations. The objective of this study is then to understand the link between the Cation Exchange Capacities (CEC) of analcimolites as a function of their analcime content and associated crystal chemistry. Mineral quantification was performed by Rietveld refinement constrained by local chemical analysis with scanning electron microscopy coupled with Energy Dispersive Spectrometry. CEC were obtained at neutral pH by performing NH4+-for-Na+ exchange (CECNa/NH4), and Na+/H+ ion exchange experiments were performed with 4 analcimolites.Results showed that the analcime crystal chemistry deduced from Rietveld refinement was in good agreement with that obtained from SEM analysis (1.99 < Si/Al < 2.53). The results showed that all samples had a positive correlation between CECNa/NH4 and analcime content until ~30 meq/100 g for a sample containing ~85wt%Riet. of analcime, and that ~6 % of the total amounts of Na+ present in the analcime could be exchanged by NH4+ and H+. Based on Si and Al aqueous measurements, results showed that exchange with Na+ is the main process consuming H+ during Na+/H+ exchange when pH > 3.5. These experimental data were then interpreted by considering a single site equal to the CECNa/NH4 value, specific for each analcimolite, and a selectivity coefficient equal to log KNa/H = 1.3 (Gaines Thomas convention) being equal for all samples investigated. Finally, these data were used to assess the role played by Na+/H+ exchange in the pH evolution of the pore water of an analcime-rich rock subjected to dynamic acidification.

Study of the Operating Cost of the Electric Pump for Mine Dewatering: Case of the SOMAÏR Uranium Mine

This study focuses on the operating cost of the electric pump used to extract water from the Artois mine owned by Société des Mines de l'AÏR. Exploitation of the SOMAÏR Artois mine uranium deposit is to be increased from the 20 m level to the 80, 100 or 120 m level; in the current phase of certain pits, access to the uranium deposit can only be achieved by a means that can draw off the water encountered. It is therefore essential to set up a drainage system to manage and evacuate the various water inflows. The main source of incoming water is the nearby water table, which is drained directly onto the mining unit.  The current drainage system has two sumps capable of storing the various water inflows without incident. The energy balance for the three (3) years of pumping was drawn up using the electricity consumption data received. Peaks appear in August for the year 2021, followed by January 2020 and May 2022. The results show that specific energy is high, resulting in higher power consumption than water production. According to the graph of performance curves P = f(Q), the power ratings obtained for flows corresponding to the 24 m head are 25 kW at a flow rate Q = 49 l/s for pump 261; 35 kW, at a flow rate Q = 59 l/s for pump 259 and 35 kW at a flow rate Q = 105 l/s for pump 234.

Experimental study of the influence of borehole parameters on prompt fission neutron uranium logging and its corrections

In prompt fission neutron uranium logging, borehole environmental parameters affect the measured results and must be corrected. In order to explore the influence of borehole parameters on the interpretation of logging results, this paper builds a sandstone type uranium ore block model to simulate the field production drilling device based on the “Epithermal/Thermal neutron counting rate ratio” (E/T) theory. The effects of borehole diameter, thickness of iron tube and well fluid on the decay rate of epithermal and thermal neutrons and their uncertainty correction methods were investigated. The results show that the effect of borehole diameter on E/T is negligible. The iron tube thickness has a certain effect on the moderation and absorption of epithermal and thermal neutrons, and its E/T increases slightly with increasing thickness. The influence of iron tube thickness on E/T is corrected and the relative uncertainty is less than 5%. The well fluid thickness also affects the decay rate of epithermal and thermal neutrons, and its E/T follows the law of negative exponential attenuation. The influence of well fluid thickness on E/T is corrected and the relative uncertainty is less than 5%. This study provides technical guidance for field well survey of uranium deposit.

Petrogenesis of Paleozoic trachyte and rhyolite in the Haidewula area, East Kunlun Orogenic Belt, and their implications for uranium mineralization

Zircon U–Pb-Hf isotopic compositions, mineralogical chemistry, and whole-rock geochemistry analyses were performed on rhyolite and trachyte from the Haidewula deposit in the East Kunlun Orogen Belt (EKOB). These analyses aimed to elucidate the genetic relationship between trachyte and rhyolite and to investigate the role of these volcanic rocks in uranium mineralization. Zircon U–Pb isotope dating indicates that the Haidewula rhyolite and trachyte were contemporaneous with emplacement ages of 421 Ma to 428 Ma, respectively. The trachyte samples exhibit high K2O/Na2O and Fe# [FeO/(FeO + MgO)] ratios, and belong to metaluminous, ferroan volcanic rock; the rhyolite samples display high A/CNK and Fe# ratios, elevated high field strength element contents, and can be classified as strongly peraluminous A2-type magma. Trace and major elemental geochemical signatures demonstrate that the Haidewula trachyte originated from the high-temperature partial melting of a mafic lower crust, followed by fractional crystallization of plagioclase, pyroxene, magnetite, and/or K-feldspar. On the other hand, the rhyolite was likely generated by high-temperature melting of granodiorite in a low water and mid-crust pressure environment, followed by fractional crystallization of feldspar and ilmenite. The occurrence of A-type volcanic rocks at Haidewula suggests that the initial timing of crustal extension in the EKOB was not later than 428 Ma. Overall, Paleozoic igneous rocks in the EKOB revealed that a post-collisional extensional regime, resulting from the rewelding of the microcontinents in eastern Gondwana, was responsible for intensive magmatism during the Late Silurian period. In comparison to other volcanic complexes hosting uranium deposits in eastern China, the relatively U-rich rhyolite and trachyte had the potential to contribute to the formation of U mineralization. In particular, the rhyolitic tuffaceous U-rich glassy volcanic rocks in the Haidewula deposit may represent favorable U-source rocks for mineralization, with uranium released through volcanic glass devitrification processes and leaching by oxidizing hydrothermal fluids.

Using seismic petrophysical modeling and prestack simultaneous inversion to provide insights into the physical properties of uranium-bearing reservoirs: Implications for favorable sites of sandstone-hosted uranium deposits

Seismic prospecting has been accepted as one of the most widely available methods for exploring sandstone-hosted uranium deposits (SUDs). However, conventional seismic interpretation faces a challenge in the identification and characterization of a uranium reservoir’s complexity. How to characterize in detail a uranium reservoir’s physical complexity and effectively improve uranium reservoir prediction accuracy remain unresolved problems. To address this, we develop a novel combination of petrophysical modeling and prestack simultaneous inversion to understand in detail the physical properties of uranium-bearing reservoirs and efficiently predict favorable SUD sites. First, we develop a workflow of rock-physics modeling for SUD logs using the Xu-White method to calculate the modulus of elasticity of the grain matrix; subsequently, we extend the Walton model for the modulus prediction of the dry rocks and the Gassmann equation for one of the saturated rocks after a massive calculation test; and then, we predict the S-wave data used for the following inversion. Second, we execute a prestack simultaneous inversion to obtain the petrophysical parameters (e.g., P-impedance, density [[Formula: see text]], shear modulus [[Formula: see text]], Lamé coefficient [[Formula: see text]], and Young’s modulus) that can provide insights into the physical properties of a uranium metallogenic environment. Accordingly, we discover that sites bearing uranium mineralization strongly correspond to areas with low elastic-parameter values (especially [Formula: see text] and [Formula: see text]), whereas nonuranium anomalies occur in high-value sites. This indicates that weakened elastic characteristics are caused by the enhancement of the total organic content and total clay mineral volumes of the uranium-bearing layers. In summary, the developed combination approach can yield an effective and accurate characterization of the geologic properties of uranium-bearing formations, and it can provide prediction factors (e.g., parameters related to the shear modulus) for uranium mineralization.

Mineral Chemistry and Chronology Investigation of Uraninite in the Jinguanchong Uranium Deposit in Eastern Hunan Province and the Implications for Geological Significance.

Jinguanchong deposit, a part of the Mingyuefeng ore field in eastern Hunan Province, China, is a typical perigranitic uranium deposit (a subtype of granite-related deposit) discovered recently with considerable uranium mineralization. Herein, uraninite, the primary ore mineral in the deposit, was investigated via scanning electron microscopy and electron probe microanalysis. Additionally, laser ablation-inductively coupled plasma-mass spectrometry was used for the first time to determine the in situ U-Pb age and the rare-earth element characteristics of uraninite. Uraninite mainly comprises UO2, CaO, and PbO with a low ThO2 content. Uraninite exhibits a low total content of rare-earth elements with a distinct fractionation between light and heavy rare-earth elements while displaying a negative Eu anomaly. The presence of major elements and rare-earth elements in uraninite suggests its formation within a hydrothermal environment at moderate to low temperatures below 350 °C, thereby classifying the Jinguanchong deposit as a typical hydrothermal vein-type uranium deposit. The uranium metallogenic age is determined to be 93.8 ± 1.4 Ma, falling within the midlate Cretaceous period. This age corresponds to the Mesozoic lithospheric extension and thinning events (approximately 85-95 Ma) in South China, suggesting that the formation of the Jinguanchong uranium deposit might be associated with the tectonic dynamics of lithospheric extension and thinning.