Uranium Mining Research Articles

The energy crossroads: Exploring the moderating role of the energy crisis on the acceptance of the development of a uranium mine

The energy crisis caused by the lack of supply from some countries involved in armed conflicts, coupled with society’s continuous demand for energy production, is leading to the proposal of new energy sources, such as the development of uranium mines to increase nuclear energy production. Mine projects (MPs) trigger numerous conflicts in the local societies involved. While for some people, they represent an opportunity for development and benefits, for others these proposals are perceived as a threat and a health risk. However, energy scarcity and price increases create a social dilemma that moderates the established relationships between the perceived risks and benefits and the valuation of energy proposals. This research aims to analyze both the weight of the factors influencing the acceptance of a uranium MP and the moderating role of the energy crisis on these factors. A total of 629 people participated in this study (371 before and 258 after the energy crisis). The participants answered a questionnaire assessing their socio-demographic characteristics, beliefs about the environment, the perceived risks and benefits, and their emotional balance, as well as their level of knowledge and acceptance of the uranium mine proposal. The results show that age, gender, and level of education and knowledge both directly and indirectly influence the acceptance of a mine. In addition, the perception of risks and benefits is associated with the emotional balance generated, explaining the level of final acceptance of the proposal. The moderation-mediated energy crisis hypothesis influences the relationship between the perceived risks and acceptance of the uranium mine. The results are discussed in order to determine factors for intervention to alleviate the social conflicts created by new energy proposals.

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.

Establishing a Mining Group of Deposit and an Exploration Grid Pattern for Uranium Ore Intercalated in Sandstone at Pa Lua - Pa Rong Area, Nong Son Basin

This research shows the results of establishing a mine group and a uranium ore exploration network in Nong Son depression sandstone, Quang Nam province based on the results of exploration of uranium ore bodies in the Pa Lua - Pa Rong area. Some main findings include: i) The uranium content in most industrial ore bodies can be attributed to a lognormal distribution function. The ore bodies (two main ore bodies are referred to as TQ1 and TQ2) have an average uranium concentration from 0,032% to 0,054% U3O8 with high variations (with the amount of variation in content (Vc) greater than 100%). The average thickness of the ore bodies is from 2,30 meters to 2,35 meters. The thickness variation coefficient (Vm) varies from 89,4% to 100,3%, indicating the unstable to very unstable type of ore body; and ii) Uranium mines in sandstones of the Pa Lua - Pa Rong type, Nong Son basin mainly belong to exploration mine group III. The most reasonable exploration approach is to use a parallel and fan-shaped network. To calculate the reserves, the distance between drilling routes is set at 50 to 60 meters. To determine the road and pavement, wet set the drilling routes to be 25 to 30 meters apart from each other. This exploration network can be applied to other sandstone mines in the Nong Son basin with similar characteristics to the Pa Lua - Pa Rong mine.
  
  
  

A mass and energy balance for a specific refuelling of Angra 2 nuclear power plant from a life cycle perspective

This work presents a detailed analytical balance of the material and energy flows associated with the nuclear fuel dynamics of the Angra 2 nuclear power plant (Brazil). A model is proposed for tabulation of material and energy flows, applied to each life stage of the nuclear fuel cycle, from extraction of raw material and production of nuclear fuel to post-use of fuel assemblies (FAs), when these are transformed into nuclear tailings. The tabulated and systematized data refer to the plant operation over a full load period. Approximately one year is the period of the plant operation after a regular refuelling and, at this period, all the materials and energy inputs are considered in addition to the wastes generated by the nuclear fuel cycle, including the ones due to operation and maintenance of the power plant in that period. Since 1/3 of the FAs of the core are replaced by fresh FAs, this analysis considers energy and material flows related to the production of fresh FAs. Related to these processes, it is taken into account what follows: 1) Uranium mining and processing, 2) Conversion of uranium concentrate into uranium hexafluoride (UF6), 3) Uranium (UF6) enrichment, 4) reconversion of the enriched UF6 to uranium dioxide (UO2), 5) Production of nuclear fuel - from the pellets to FAs, 6) Power generation from plant operation, and 7) Generation and management of nuclear tailings arising from the regular operation of the plant in that period. The analysis of systematized data from the various stages of the cycle allows a broader analysis and the perception of critical aspects, such as the need for technological improvements, logistical advances, care for the environment and public health, increased energy efficiency, in addition to the need for materials recycling, among other possibilities.

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.

Analyze the Impact of Nuclear Energy on Many Aspects of Life Cycles—Review

AbstractEnergy has long been seen as an important factor in meeting needs of people, in order to sustain and support the economic growth and livelihood. To understand the various technological processes in the nuclear power life cycle, it is first necessary to know the types of fuels used today. There are two types of gasoline in use today, “open” and “partially closed,” respectively, referred to as “single cycle” (OTC) and “double cycle” (TTC). A distinction must be made between “partial” closed fuel cycles, as they apply to current critical (thermal neutron spectrum) reactor technology, which is limited to two passes, and “full” closed cycles, which allow for greater circulation of spent oil but must be used. Fast reactors (FR) are included in the reactor fleet. Many recoveries of FR—already proven but not yet widely used in industry—will lead to reduced demand for uranium mining. In this section, references to “closed” fuel cycles include “partially” closed cycles, i.e., TTCs. What type, if any, is the correct content or information in question? Analysis of the world's energy consumption in recent years shows that the world's energy consumption has increased by 50% in less than a decade.

Уран и редкоземельные элементы в диктионемовых сланцах Прибалтийского бассейна (Кайболово-Гостилицкая площадь)

The article presents the results of the study of dictyonema shales of the Baltic basin (Leningrad Oblast, Kaibolovo-Gostilitsy prospecting area) for uranium (updated data on uranium mineralization of dictyonema shales) and rare earth elements (for the first time – as a new promising raw material source). At the same time, updated author’s data on the total metalliferous content of dictyonema shales was made In relation to uranium, its average content in dictyonema shales has been clarified, the distribution of uranium in the section of sedimentary strata according to new well profiles has been given, and the features of its distribution have been clarified, in comparison with earlier authors’ publications on this object of research. For rare earth elements in dictyonema shales, the results on their concentrations on a much larger analytical material are presented (670 samples, instead of 88, data on which were published earlier). For the first time, the features of the distribution of rare earth elements over the prospecting area and in the section of sedimentary strata along the profiles of wells are illustrated. New data on the petrographic composition of dictyonema shales are presented. An additional study of mineral impurities of dictyonema shales was carried out using a new method of areal scanning of preparations with an electron probe microanalyzer using the “Feature” software module. The correlations between the concentrations of uranium and rare earths with other micro- and macroelements, the forms of uranium and rare earth elements in dictyonema shales, geochemical indicators, conditions and genesis of the formation of uranium and rare earth mineralization developed in them was clarified. Based on an earlier assessment of the resource potential of uranium and rare earths, a modern assessment of their prognostic mineral resources and possible recoverable industrial reserves and the cost of potential ore raw materials of the studied acute-deficient metals for energy and a number of important industries has been made. The authors express the opinion that the mineral resource base of uranium and rare earth elements in Russia can be significantly increased due to the presence of these critical metals in the dictyonema shales of the Baltic sedimentary basin, since only within the studied Kaibolovo-Gostilitsy prospecting area the largest uranium resources and large resources of rare earths have been discovered, which may increase even more with further geological research in the conditions of a developed infrastructure of the middle zone of the Russian Federation.

Water-soluble rare earth elements (REEs) recovered from uranium tailings

The global energy transition from fossil fuels to renewable sources poses substantial challenges to increase metal production, including industry-critical rare earth elements (REEs). Environmental and social concerns obfuscate the production of these ‘green’ metals and only ∼1% of REE demand is met from recycling. This work highlights the potential for the ‘economic rehabilitation’ of the Mary Kathleen Mine, a relinquished uranium (U) mine with very high (∼3 wt%) total REE concentrations within the tailings storage facility (TSF). Leaching of the tailings revealed that approximately 5% of the REEs are water-soluble, suggesting the possibility for in situ extraction. Using an in situ water leach, the projected total REE recovery is >10,000 t, which would exceed the total amount of U recovered (7,532 t) during the initial mining operation. The proposed in situ recovery would offer a truck-free mine, using solar energy and water recycling technologies to recover REEs from a waste source, reducing environmental contamination.

RECONNAISSANCE SURVEY OF MOTHBALLED URANIUM MINING FACILITIES AND SETTLEMENTS IN THE SOUTHERN PART OF THE NORTH-KAZAKHSTAN REGION

This paper provides data of the reconnaissance (preliminary) radiation survey of mothballed uranium mining facilities (MUMF) and adjacent settlements in the southern part of the North-Kazakhstan region (NKR). It is shown that, according to the level of EDR values, MUMF locations, when the public periodically stays in these areas, do not pose any radiation hazard. The exception is Grachevskoe MUMF where EDR values reached up to 14.0 µSv/h. Around the settlements, EDR values vary from 0.1 to 0.5 µSv/h. Elevated values are noted on highways. Regulatory values of radon EEVA were also found to be significantly exceeded in Toksan bi vil. A minor excess of radon EEVA was detected in Novoukrainka vil. Exceedance of the content of 238U up to 4 MPC was detected in sources of drinking water supply. Exceedances of up to 5 MPC for 238U were also found in natural waters.  The total alpha activity showed an excess of up to 15 MPC. Natural waters exhibit an excess of up to 10 MPC. Based upon the data analysis during the reconnaissance survey, the Grachevskoe MUMF and Novoukrainka settlement were selected for a detailed survey.

Study on the remediation of uranium-contaminated soils by compound leaching: Screening of leaching agents and a pilot-scale application

To solve the problem of soil environmental pollution resulting from uranium mine development and production, a soil slurry reactor was used to evaluate the use of chemical leaching to remediate uranium-contaminated soils and to analyze possible uranium removal mechanisms through laboratory-scale trials and pilot-scale trials. A laboratory-scale trial comparing different reagents and operating methods revealed that the removal of total uranium from contaminated soil could reach 91.18% under optimal conditions when FeCl3, OA, NaClO2, and HEDP were used as eluents.Based on the optimal ratio and operating conditions determined from laboratory-scale trials, a pilot-scale trial was conducted around a uranium mining area: soil leaching remediation was conducted in two 3 m3 soil-slurry reactors to verify the practicality of the leaching technology and examine the functionality of the remediated soil. The experimental results showed that the rate of uranium removal from contaminated soil by the chemical leaching method was greater than 80%. FTIR, XRF and enzyme activity analysis proved that remediation restored the original soil function and reduced the ecological risk, indicating that the chemical leaching technology was environmentally friendly and economical. These findings provide insight to guide the future assessment and remediation practices of uranium-contaminated sites.

Assessment of radon transportation and uranium content in the tectonically active zone of Himalaya, India

The study shows how geology and tectonic activity affect the soil gas 222Rn concentration. The tectonically active zone, namely the Ghuttu region, which is located within the Himalayan seismic belt, was studied to decipher its impact on soil gas 222Rn concentrations. A soil gas 222Rn study was performed in the soil at a depth of 30 cm, and it varied from 426 ± 156 Bq m−3 to 24,057 ± 1110 Bq m−3 with an average of 5356.5 ± 1634.6 Bq m-3, and at 60 cm below the soil surface, the concentration varied from 1130 ± 416 Bq m−3 to 30,236 ± 1350 Bq m−3 with an average of 8928.5 ± 2039.5 Bq m−3. These concentrations vary in soil from −3.4 % to 437.3 % as the depth moves from 30 cm to 60 cm. The variation in uranium content also shows anomalies, and higher values of uranium content in the soil affect the radon concentration in the study area. The average soil gas 222Rn concentration in the Ghuttu window was found to be higher than that in its surrounding region. This is likely due to transportation from daughter products of uranium. 222Rn mass exhalation rate measurements were also carried out, and a weak correlation with the soil gas 222Rn concentration was observed. A significant variation in the mass exhalation rate was noticed in tectonically active areas. This study is vital to understanding the behavior of radon and uranium in tectonic regions.

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.

Advanced “turn-on” colorimetric uranium platform based on the enhanced nanozyme activity of a donor-acceptor structured covalent organic framework

BackgroundThe increasing uranium containing wastes generated during uranium mining and finishing pose a huge threat to the environment and human health, and thus robust strategies for on-site monitoring of uranium pollutant are of great significance for environmental protection around uranium tailings. ResultsHerein, a facile “turn-on” colorimetric platform that can achieve uranium detection by spectrometry and naked eyes was developed based on the uranium-enhanced nanozyme activity of covalent organic framework (JUC-505). Thanks to the extended π-conjugated skeleton and donor-acceptor (D-A) structure, JUC-505 exhibited superior photo-activated nanozyme activity, which would be prohibited when the cyano group in JUC-505 skeleton was transformed to the amidoxime group. Further results elucidated that the coordination of uranium with amidoxime groups led to the electron transfer between uranium and the JUC-505-AO skeleton, and thus significantly restored the nanozymatic activity of JUC-505-AO with the subsequent remarkable color changes. Moreover, the uranium concentrations in uranium tailing wastewater detected by the present “turn-on” colorimetric method were well agreed with those by ICP-MS, demonstrating a high accuracy of the present method in real samples. SignificanceThe D-A structured JUC-505 with superior photocatalytic property and nanozymatic activity was applied to facilitate colorimetric detection of uranium, which displays the advantages of low detection limit, excellent selectivity, fast response and simple operation for uranium detection in real samples, and shows a great potential in on-site monitoring of uranium pollutant around uranium tailings as well as nuclear power plant.

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.

Magnetic alginate supported potassium manganese ferrocyanide for the recovery of uranium from acidic wastewater

Abstract With the rapid development of the atomic energy industry, the demand for nuclear fuel has risen, while the limited resources of uranium mines make it difficult to meet the needs of the future development of nuclear energy. Expanding sources of uranium acquisition is necessary, and the enrichment and recovery of precious uranium from uranium-containing wastewater is invaluable. By synthesizing alginate supported potassium manganese ferrocyanide nanocomposites with magnetic response (KMnFC/MA/Fe3O4), the high efficiency adsorption and separation of uranium in acidic uranium-containing wastewater can be realized conveniently and quickly. The magnetic composite was characterized by a variety of technical means, and the adsorption behavior of the magnetic material on uranium was studied by static adsorption experiments under different environmental conditions. The adsorption kinetics and isotherm of uranium by KMnFC/MA/Fe3O4 were studied by using some common linear adsorption models. The results show that the adsorption rate of KMnFC/MA/Fe3O4 on uranium is fast, and the adsorption equilibrium can be reached within 90 min. The adsorption process conforms to a pseudo-secondary kinetic model and is dominated by chemisorption. The adsorption of uranium by KMnFC/MA/Fe3O4 magnetic material is single molecular layer adsorption, and the maximum adsorption capacity is 425.5 mg g−1 at 35 °C. KMnFC/MA/Fe3O4 is a promising adsorbent in the field of acidic low-concentration uranium wastewater treatment because of its good effect on the treatment of low concentration uranium wastewater, the concentration of uranium in the wastewater reaches the emission standard after treatment and it is easy to be separated magnetically after adsorption.

An electrochemical method for the regeneration of trivalent iron to increase the efficiency of in-situ leaching of uranium

Due to the increasing demand for electricity with the development of production and general infrastructure, increasing the production of uranium as an economically and environmentally efficient source of energy is an urgent problem. The purpose of this study is to develop an electrochemical method for the regeneration of iron (III) ions used as a uranium oxidizer in the process of in-situ leaching of uranium minerals with sulfuric acid solutions. Methods. The mechanism of reactions in the iron (II)-iron (III) redox system was studied by recording potentiodynamic polarization curves and conducting electrolysis of the oxidation of divalent iron ions under galvanostatic conditions. Results and discussion. Cathode-anodic and anodic-cathode cyclic polarization curves taken on platinum electrodes showed that the redox reactions of iron ions are reversible and these reactions occur at a slight overvoltage. The influence of the main electrochemical parameters (current density, concentrations of iron (II) ions and sulfuric acid) on the oxidation of divalent iron ions was studied for the first time using granular anode electrodes, the electrode spaces of which are separated by an anionite membrane. It has been found that the use of granular graphite electrodes in the oxidation divalent iron ions increases the current output by more than 2 times compared to a plate graphite electrode. Conclusion. According to the results of the study, it was noted that under optimal conditions, the current output of the oxidation of divalent iron ions exceeds 90%. Extensive research has shown that trivalent iron ions, widely used in the in-situ leaching process for uranium production, can be regenerated by electrochemical methods.

Relationship between the genesis of Changlinggang alkaline rocks and uranium mineralization in the 414U-Th deposit, Jianshui County, Yunnan Province, China

Alkaline rocks identified in the 414 U-Th deposit in Jianshui County, Yunnan Province, exhibit intense spatial correlation with uranium mineralization. However, limited investigations into their genesis have had an adverse impact on our understanding of uranium mineralization. Analyses of major and trace elements, U-Pb chronology, and petrography were conducted on alkaline rocks. The results indicate that anorthosite, which is rich in alkalis, high in potassium, peraluminous, enriched in rare earth elements (U, Th, Rb, and Zr) and deficient in Sr, Ba, Ti, and P, predominates the lithology. The light and heavy rare earth fractionation of the material is readily apparent (LREE/HREE=7.89–46.72), and the presence of Eu negative anomalies (δEu=0.65–0.81) suggests that the region from which the magma originated is a metasomatism-enriched mantle where the source material originates from the transition zone between garnet-lherzolite and spinel-lherzolite in the EMII-enriched lithospheric mantle. This area underwent metasomatization by subduction material from the Paleo-Pacific Ocean and during the ascent process, magma experienced a certain degree of partial melting and a significant degree of crystallization differentiation. The diagenesis of the syenite (186.64 ± 3.76 Ma) occurred after the closure time of the Paleotethys Ocean (237 Ma) in a dynamical context of an intra-terrestrial rift environment following subduction of the oceanic plate. In summary, the U and Th present in the 414 U-Th deposits underwent isomorphism within biotite and feldspars during the hydrothermal mineralization stage of magma evolution, where they were enriched in minerals through the separation and crystallization of alkaline magma.

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.

Case study of fluorite mineralization using traditional and laser spectroscopic techniques, homret akarem area south eastern desert, Egypt

Green fluorite samples from Homret Akarem, eastern desert Egypt, were investigated by laser-based Raman spectroscopy to study the effect of rare earth elements (REEs) and natural radiation from the surrounding environment on their physico-chemical properties, taking into consideration the geological setting. Geochemical data of trace elements display fluorite enrichment with Y, Pb, Sr, Sn, and other REEs. XRD showed lattice parameters with values higher than those for synthetic fluorite due to the substitution of Ca by Sr and less likely by radiation from U. A considerable shift in the binding energy (BE) for Ca and F obtained from the XPS spectrum indicates that U carried by the hydrothermal solutions formed a discontinuous thin film on the surface of fluorite. Laser-Raman spectroscopy showed strong peaks below 500 cm−1 and both shallow and weak peaks above 500 cm−1. The strong peaks indicate that the substitution of Ca by Sr, point defects, and natural radiation caused by U have a stronger effect on the crystal structure than REEs. Raman spectroscopy supported the initial reports of uranium minerals like Rutherfordine, Kasolite, Soddyite, and Uranophane-alpha.

A numerical model for the prediction of radon flux from uranium mill tailings at Jaduguda, India.

Solid process fine waste or tailings of a uranium mill is a potential source of release of radiologically significant gaseous radon (222Rn). A number of variables such as radium (226Ra) content, porosity, moisture content, and tailings density can affect the extent of emanation from the tailings. Further, if a cover material is used for remediation purposes, additional challenges due to changes in the matrix characteristics in predicting the radon flux can be anticipated. The uranium mill tailings impoundment systems at Jaduguda have been in use for the long-term storage of fine process waste (tailings). A pilot-scale remediation exercise of one of the tailings ponds has been undertaken with 30cm soil as a cover material. For the prediction of the radon flux, a numerical model has been developed to account for the radon exhalation process at the remediated site. The model can effectively be used to accommodate both the continuous and discrete variable inputs. Depth profiling and physicochemical characterization for the remediated site have been done for the required input variables of the proposed numerical model. The predicted flux worked out is well below the reference level of 0.74Bqm-2s-1 IAEA (2004).