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Copyright of World Nuclear Geoscience is the property of World Nuclear Geoscience Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Various symbiotic/associated oil and gas resources have been found in the exploration area of Shengli Oilfield， and some of them serve as strategic resources for guaranteeing the security of national defense， agriculture， high-tech， and other industries， which are of great value in development and utilization. The current exploration and development status， occurrence characteristics， ore-forming conditions， and comprehensive utilization prospects of helium， brine （potassium salt）， and uranium ore that have been deeply studied and industrially produced in China were analyzed. The results show that ① the high helium anomalies are mainly distributed in more than 10 areas of the Jiyang Depression and Qaidam Basin， as well as in multiple layers of the Proterozoic-Cenozoic， associated with conventional natural gas， non-hydrocarbon gas， and shale gas； ② Jiyang Depression and Qaidam Basin provide the paleoclimate and palaeoenvironment for developing brine （potassium salt） from the Paleogene to the Quaternary. The oilfield water in Dongying Sag contains abundant amounts of bromine， lithium， and potassium， and more potassium and lithium are found in the oilfield water in Qaidam Basin， with the content in some areas reaching industrial grade； ③ the sandstone is the primary type of uranium ore. The multiple wells in Chepaizi Uplift exhibit highly abnormal gamma values in the Cretaceous and Neogene， indicating that this area is the most favorable prospective area of associated uranium ore. In other exploration areas of Shengli Oilfield， such as Tuha Basin， Qaidam Basin， and Jiyang Depression， the forming conditions for uranium ore are observed， including uranium sources， structures， lithofacies， hydrogeology， etc.， and natural gamma logging data from some wells show high abnormal values. Overall， the symbiotic/associated oil and gas resources in the exploration area of Shengli Oilfield show the characteristics of various types， multiple layers， and wide abnormal areas. It is necessary to fully take the natural advantages of Shengli Oilfield in terms of basic exploration data， basic geological achievements， and engineering facilities，to systematically carry out research on the reservoir forming （ore-forming） law of symbiotic/associated oil and gas resources， evaluate resource potential， and innovate extraction technology as soon as possible， to achieve a new business growth pole.

Aiming at the problems such as low settling speed and poor solid-liquid separation effect of a uranium ore high-calcium slurry, static flocculation method was used to settle high-calcium pulp of a uranium ore, and the effects of flocculant type, dosage, mixed flocculant ratio and adding method on the settling effect were investigated. The results show that the settling rate of high calcium pulp can be significantly increased by the mixed flocculant prepared by WZ944 flocculant and 5330 flocculant. The optimal mass ratio of the two flocculants is 1:1, and the minimum dosage of the mixed flocculant is 35 g/t. The research results can provide reference for the optimization design of the uranium ore solid-liquid separation process. [ABSTRACT FROM AUTHOR]

Overlapping uranium and coal resources are widely distributed in the basins of China. The current uranium–coal coordinated mining model, mining interaction, and multi-phase and multi-field coupling mechanisms remain unclear, thereby substantially restricting the mining of overlapping uranium and coal resources. This article reviews the overlapping uranium–coal mining technology and conditions, summarizes the main problems faced by the coordinated mining of coexisting uranium–coal resources, proposes a dynamic coordinated mining technology system for the entire life cycle of coexisting uranium–coal resources, and describes the multiphase and multifield coordinated mining of co-associated uranium–coal resources. The multifield coupling mechanism clarifies the solid–liquid–gas three-phase spatiotemporal coupling effects of the stress, fracture, seepage, geochemical, pressure, and microbial fields, and explains the safe and efficient mining technology of uranium and coal resources, and the coordinated mining and isolation technology of uranium and coal. "Trinity" pollution prevention and control technology and other key research directions are discussed to promote green, efficient, joint, and coordinated mining of uranium and coal. [ABSTRACT FROM AUTHOR]

Copyright of Petroleum Geology & Recovery Efficiency is the property of Petroleum Geology & Recovery Efficiency and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Natural Gas Geoscience is the property of Natural Gas Geoscience and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Uranium Mining & Metallurgy is the property of Uranium Mining & Metallurgy Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This research investigated the feasibility of employing organic acids, like citric acid, produced by Aspergillus nidulans MT355567 in a bioleaching process to recover uranium (U) from a low-grade rock sample. The optimal conditions for fungal growth and maximum citric acid (CA) synthesis across three distinct media were determined. The maximum citric acid concentration was produced on medium made from wheat bran (83%) and tea waste (77%). An investigation was carried out to see how citric acid and, by consequence, uranium bioleaching affinity, were affected by varying carbon sources, nitrogen sources, pH, temperature, incubation period, ore particle size, and the solid–liquid ratio. At 25 °C and a pH of 5.0, media containing 100 g/L of sucrose as a carbon source and peptone as a nitrogen source made the highest yield of citric acid and U bioleaching. Higher U bioleaching was achieved with ore particles 0.075 mm at a ratio of 2 g/L after only 30 min of contact with the fungal filtrate. Iron interference has a negative impact on uranium extraction. Interestingly, none of the conditions applied to enhance CA synthesis and U-bioleaching caused iron (Fe) dissolution. Based on these findings, it appears that bioleaching using A. nidulans MT355567 metabolic products is a promising economic and ecofriendly technology for extracting uranium from low-grade ore that might be adopted on a pilot scale. summarizing the experimental workflow for bioleaching of uranium from low-grade ore using citric acid produced by Aspergillus nidulans. The process involved optimizing A. nidulans growth and citric acid biosynthesis, evaluating factors influencing bioleaching activity of the acid metabolite solutions, and finally applying the optimized conditions to bioleach uranium from the ore sample. The schematic illustrates the key steps and the optimal condition for Aspergillus nidulans growth medium preparation using agricultural wastes, downstream application of metabolite synthesized for uranium bioleaching [ABSTRACT FROM AUTHOR]

Copyright of Bányászati és Kohászati Lapok - Kohászat is the property of Hungarian Mining & Metallurgical Society and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In 1981-1983, before the start of full production, trial mining of uranium ore was carried out at the Žirovski vrh mine to test the methods of geological and radiometric control as well as the technical methods of extraction. The trial excavation was done in block 1, in the extreme NW part of the mine in the upper fold of the double S structure. In this block, the ore deposits bodies were found only in the horizon of grey sandstone about 20–30 m thick. Geological monitoring of the excavation confirmed that the sandstones were deposited in sequences from a few dm to more than 2 m thick. The sequence usually graded bed started with coarse-grained sandstone, with pebbles of quartz and mudstone occasionally present at the base. Upwards, coarse-grained sandstone often passed into medium-grained, and more rarely into fine-grained sandstone and siltstone. The sandstones were characterized by the presence of organic fragments, which created an anoxic environment during diagenesis and that in turn enabled uranium to precipitate from the groundwater and concentrate in the host rock. Most often, ore bodies were found in coarse-grained sandstones, usually in several sedimentary sequences. As such, ore bodies appear in several sequences, usually under 1 m thick. In some places ore bodies can join together, exceeding 5 m. The length of the uninterrupted ore body in the longitudinal direction was up to 150 m, the width ranges from a few meters to more than 40 m. In the intermediate areas where the ore body is interrupted, we observed that the sandstones changed from dark grey and grey to light grey and greenish grey. These sandstones were usually barren or contained only small concentrations of uranium. In the longitudinal direction, such a transition took place between cross-sections P-35 and P-35a, where excavation was completed. Cross-sections P-36 and P-37 were also investigated inside the mine, where predominantly greenish-grey sandstone with only rare lenses of poor uranium concentrations appeared. Further to the west, two cross-sections 1.3 and 2.8 km from the mine area were also explored with surface boreholes. Grey and greenish-grey sandstones with very rare remains of organic matter and very rare traces of mineralisation were found in these boreholes, alternating with siltstones. Block 1 is therefore considered the boundary block on the NW side of the mine, intended for extraction.

Uranium ore is one of the most important mineral resources in nuclear industry, and the nuclear industry is in urgent need of an analytical technology that can quickly and effectively explore uranium ore resources. Rapid and effective exploration of uranium ore resources could promote the stable and healthy development of the nuclear industry. Laser induced breakdown spectroscopy (LIBS) is a kind of emission spectral element analysis technology, which has the advantages of rapid detection of multi-target elements, and can realize the purpose of rapid and accurate field exploration and analysis of uranium resources. The quantitative analysis of U in uranium ore was carried out based on LIBS technology and machine learning. A total of 12 groups of experimental samples were prepared in this work, and 9 groups of samples were set as training sets for model establishment and hyper-parameter optimization. Three sets of samples were set for model validation. Partial least squares(PLS) and Random forest(RF) algorithms were used to establish a quantitative model, and the hyper-parameters of the two models were optimized by the ten-fold cross-validation method. Finally, the quantitative effects of the two models were verified and compared by three verification sets. After hyper-parameter optimization, both quantitative models had good linear correlation and model stability. The linear correlation coefficient of RF quantitative model was 0.996, while that of PLS quantitative model was 0.997. In terms of model validation, the relative errors of RF model for the three validation sets were 22.33%, 12.79% and 12.04%, respectively. The relative errors of PLS model for the three verification sets were 4.33%, 6.63% and 6.85 %, respectively. Compared with the verification results of the two quantitative models, the relative error of the PLS model on the three verification sets was lower than that of the RF model, which indicated that the PLS model had higher quantitative accuracy than the RF model. Therefore, compared with RF algorithm, PLS algorithm is more suitable for quantitative analysis of U LIBS in uranium ore. [ABSTRACT FROM AUTHOR]

Based on an analysis of the spatial distribution of uranium grade in 338 boreholes of a uranium deposit in Xinjiang, the enrichment and spatial variation of uranium ore in two stopes of the deposit are discussed using multifractal theory. The distribution characteristics of the uranium ore of the two stopes are studied by multifractal parameters: the scaling exponent of mass τ (q) , the scaling exponent α (q) of each sub-set and its corresponding fractal dimension f (α) , the fractal dimension D0 and information dimension D1. The differences of uranium distribution in the two stopes can be quantified well by using multifractal spectrum and multifractal parameters such as Δ α , Δ f and R. After a comprehensive multifractal distribution analysis, 10 m × 10 m is defined as a fence unit, and the window sizes ε = 3 , 6 , 9 ⋯ , 45 are set; the singularity exponents α of the two stopes are calculated by using this element concentration–area method. The results show that the multifractal theory and model can organically combine spatial structure information, scale change information and anisotropy information to obtain low-grade and weak mineral resources information and can effectively distinguish complex and superimposed anomalies. This will provide a basis for the local concentration and spatial variation rules of uranium distribution and the design of the parameters of the leaching uranium mining well site. [ABSTRACT FROM AUTHOR]

To improve the utilisation of uranium resources while reducing the radioactive contamination of uranium slag by 226Ra, the effects of various factors on uranium–radium co-leaching from uranium ore were investigated. For nitric acid agitation leaching, the optimal performance was achieved using 80 mesh ore in 4 mol L−1 nitric acid at 40 °C for 4 h with a liquid-to-solid ratio of 3. Under these conditions, the uranium leaching rate was > 99% and the radium leaching rate was > 93% with standard deviations of < 0.04% and < 0.7%, respectively. Thus, this approach realises simultaneous uranium and radium leaching at high rates. [ABSTRACT FROM AUTHOR]

BACKGROUND Studying the characteristics of rare earth elements in uranium ore can determine the source of the ore-forming fluids, the mineralization environment, and the physical and chemical conditions. It is particularly important to accurately determine the content of rare earth elements in uranium ore. At present, rare earth elements are mainly determined by inductively coupled plasma-mass spectrometry (ICP-MS). High-pressure closed acid-dissolution is commonly used. The open acid dissolution method is rarely used because perchloric acid is routinely used to dissolve samples, and the temperature is relatively low, which may cause incomplete decomposition of some samples. OBJECTIVES In order to solve the problem that the rare earth elements have contents lower than real values in open acid dissolution. METHODS The tetracid system of nitric acid-hydrofluoric acid-perchloric acid-sulfuric acid was used in the open acid dissolution method. ICP-MS with Rh as internal standard was used to determine 15 rare earth elements in uranium ore. RESULTS The relative standard deviation (RSD) of the 15 rare earth elements was between 0.54% and 5.98%, and the recovery was between 96.0% and 106.0%. Applying to national rock standard materials (GBW07103, GBW07104, GBW07122), the measured values were consistent with the standard values, and the relative error (RE) was between -8.33% and 7.24%, indicating that this method was effective for the determination of rare earth elements. CONCLUSIONS The method has simple operation, accurate and reliable results, and is suitable for the determination of rare earth elements in large quantities of uranium ore.

Copyright of Chinese Journal of Inorganic Analytical Chemistry / Zhongguo Wuji Fenxi Huaxue is the property of Beijing Research Institute of Mining & Metallurgy Technology Group and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Geology & Exploration is the property of Geology & Exploration Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Geologija (0016-7789) is the property of Geological Survey of Slovenia and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The use of similarity theorems for simulation of the technological process of mineral extraction is considered. The list of parameters that significantly influence the process of underground leaching of minerals is defined. Using these parameters and fundamental laws of physics and chemistry, mathematical functions are determined to describe the processes’ behaviour under these conditions. The obtained mathematical functions make it possible to develop a computer model of polymetallic ores leaching. This allows for the prediction of the volume of extracted concentrate with minerals from the ore mass with the associated compounds. The obtained results of calculations showed a change in the volume of minerals extracted from the rock mass depending on the mass of the working agent, the volume of leached ore and the solvent percolation rate. The results of the research can be used at mining enterprises to extract polymetallic ores by underground leaching. Also, they allow for the estimation of the economic issues from mining the ore reserves.

In this paper, we review both practical and theoretical assessments for evaluating radon geohazards from permafrost landforms in northern environments (>60º N). Here, we show that polar amplification (i.e. climate change) leads to the development of thawing permafrost, ground subsidence, and thawed conduits (i.e. Taliks), which allow radon migration from the subsurface to near surface environment. Based on these survey results, we conjecture that abruptly thawing permafrost soils will allow radon migration to the near surface, and likely impacting human settlements located here. We analyze potential geohazards associated with elevated ground concentrations of natural radionuclides. From these results, we apply the main existing legislation governing the control of radon parameters in the design, construction and use of buildings, as well as existing technologies for assessing the radon hazard. We found that at present, these laws do not consider our findings, namely, that increasing supply of radon to the surface during thawing of permafrost will enhance radon exposure, thereby, changing prior assumptions from which the initial legislation was determined. Hence, the legislation will likely need to respond and reconsider risk assessments of public health in relation to radon exposure. We discuss the prospects for developing radon geohazard monitoring, methodical approaches, and share recommendations based on the current state of research in permafrost effected environments.

Copyright of Rudarsko-Geolosko-Naftni Zbornik is the property of Faculty of Mining, Geology & Petroleum Engineering and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The Metropolitan Region of Recife, the capital of the state of Pernambuco in northeastern Brazil, has a high demographic density and developed under a region of marine phosphorus with high concentrations of phosphate that naturally contains uranium ore, producing ionizing radiation from descendants of the radioisotope 238U where 226Ra and 210Pb are of great importance in verifying the probable harmful effects on human health due to environmental radioactivity. The supply of drinking water is the responsibility of the state-owned company COMPESA which uses wells of great depth to complete the supply of drinking water for the entire population. COMPESA and the RAE Group of the Federal University of Pernambuco developed a joint project to assess the concentrations of 226Ra and 210Pb and estimate the equivalent and effective doses caused by ingesting these radiation sources. According to the above, this research aimed to evaluate concentrations of 226Ra and 210Pb in drinking water samples from 110 deep wells in Recife. The activities of 226Ra and 210Pb ranged from 1.4 ± 0.3 to 119.3 ± 12.9 and from 25.6 ± 3.3 to 563.2 ± 45.6 mBq.L−1, with arithmetic means of 48.1 ± 3.8 and 231.1 ± 20 mBq.L−1, respectively. The equivalent doses average in bone tissue due to 226Ra and 210Pb were 0.45 ± 0.04 and 3.9 ± 0.37 mSv.y−1, and the annual average effective doses were 0.01 ± 0.00 and 0.13 ± 0.01 mSv.y−1, respectively. [ABSTRACT FROM AUTHOR]

Copyright of Uranium Mining & Metallurgy is the property of Uranium Mining & Metallurgy Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

External (in-air) Particle Induced Gamma-ray Emission (PIGE) setup of FOlded Tandem Ion Accelerator (FOTIA), Bhabha Atomic Research Centre (BARC) was utilized for determining concentrations of low Z elements (Si, Na, Al and F) in geological samples by a simple and novel sample preparation method using thin Mylar films to pack direct solid samples. Low energy proton beam was utilized and the current-normalized count rates of analytes were obtained using the count rate of tantalum, the beam exit window material. Meticulousness of the method was ascertained by analysing different CRMs and compared with conventional pelletisation method. Proposed method was adopted for elemental analysis in uranium ore samples for possible nuclear forensic applications. [ABSTRACT FROM AUTHOR]

Copyright of Uranium Mining & Metallurgy is the property of Uranium Mining & Metallurgy Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Rock & Mineral Analysis is the property of Editorial Board of Rock & Mineral Analysis and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Uranium Mining & Metallurgy is the property of Uranium Mining & Metallurgy Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of World Nuclear Geoscience is the property of World Nuclear Geoscience Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Radiation exposure in humans can emanate from natural radionuclides through uranium and thorium decay series as well as40K due to emitted ionising radiations. It is important to estimate the exposure of humans to the diverse sources of radiation. In this study, the activity concentrations of natural radionuclides238U and232Th in granitic rock samples from uranium mine sites in parts of Northern Nigeria were measured, by inductively coupled plasma-mass spectrometry. The highest values of238U and232Th concentrations (924.56 ± 17.13 and 21.96 ± 1.28 Bq/kg, respectively) were observed at Mika-I and Riruwai. Furthermore, the radiological exposure parameters (i.e., absorbed dose rate in air [D], annual effective dose [external], radium equivalent activity (Raeq), external exposure index (Hex), internal exposure index (Hin), and representative level index (Iγand Iα) were estimated and compared to the international recommended values. In terms of terrestrial gamma radiation from granitic rock within the study area, it does not pose any significant radiation exposure to the workers and dwellers.

Microwave pretreatment based on selective heating effectively improved the bioleaching properties of encapsulated granite-type uranium deposits. A mixed bacterial strain containing Acidithiobacillus ferrooxidans and Acidithiobacillus thiooxidans was used to leach uranium from granite-type uranium ore pretreated by microwave. Effect of three important variables (i.e. pH, pulp concentration, Fe2+ concentration) on uranium leaching was investigated with response surface methodology based on central composite design. The most influential factor is the Fe2+ concentration, followed by the pulp concentration and the initial pH of the leaching system. The interaction between Fe2+ concentration and pulp concentration has the most significant impact on uranium leaching. The optimized conditions are as follows: pH of 1.58, pulp density of 10.11%, Fe2+ concentration of 3.67 g/L and the predicted maximum uranium extraction is 93.91%, which is consistent with the experimental result (93.71%). Kinetics studies shows the biological leaching of the uranium ore pretreated by microwave is jointly controlled by chemical reaction and diffusion, but mainly controlled by chemical reaction with apparent activation energy of 71.17 kJ/mol. This may be ascribed to the increase in cracks and porosity of the ore after microwave pretreatment, which strengthened the diffusion effect of the bioleaching process. [ABSTRACT FROM AUTHOR]

We evaluated the effect of uranium bioleaching and mechanism by microwave pretreatment on uranium embedded in granite. The maximum uranium bioleaching ratio reached 93.1% after an ore sample was pretreated with microwave at 10 kW for 10 min, which was approximately 20% higher than untreated. After microwave pretreatment, the generation of micro-cracks can provide more adsorption sites for bacteria and promote contact between uranium-bearing minerals and leaching solution, a portion of the strongly bound uranium in the uranium ore was transformed into weakly bound uranium, and insoluble U(IV) into soluble U(VI), further improving uranium leaching ratio. [ABSTRACT FROM AUTHOR]

Copyright of Hydrometallurgy of China is the property of Hydrometallurgy of China Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Hydrometallurgy of China is the property of Hydrometallurgy of China Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Nonferrous Metals (Mineral Processing Section) is the property of Beijing Research Institute of Mining & Metallurgy Technology Group and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of World Nuclear Geoscience is the property of World Nuclear Geoscience Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Uranium uptake, translocation and its effects on leaf anatomy in vetiver grass (Vetiveria zizanioides L. Nash) grown in hydroponics were investigated at a wide range of concentrations. At concentrations below 200 ppm (1, 5, 25, 100, and 200 ppm) almost 90–95% of uranium was depleted from the medium within 3 days of treatment, while at other concentrations viz., at 318, 500, 619, 1,000, 5,000, 7,500, and 11,900 ppm, it reached a maximum between 7 and 14 days, with a marginal increase in the depletion thereafter. Most of the uranium could be recovered from plants at concentrations below 200 ppm. On the contrary, a significant reduction in the recovery of uranium was noticed at higher concentrations and the percentage of recovery dropped from 82% at 318 ppm to 35% at 11,900 ppm. While most of the uranium taken up by the plants could be recovered from roots at lower concentrations, a preferential translocation of the element to shoot occurred at concentrations beyond 1,000 ppm. Histological studies of leaves from plants treated with 1,000 ppm uranium displayed the formation of multilayered cells between the epidermis and vascular bundles on the adaxial side in the distal regions of the leaves. The plants were also found to tolerate and survive the radiological and chemical constituents of both uranium mill tailings soil as well as various effluents of uranium mine and mill operations. Further, they could also survive in uranium ore containing 600 ppm of triuranium octoxide (U3O8) and could withstand the amendment of ore with citric acid. The ability of vetiver to take up uranium from solutions to high levels and its survival in effluents, mill tailings soil, and ore coupled with its ecological characteristics makes it an ideal plant for phytoextraction of uranium. [ABSTRACT FROM AUTHOR]

The ability to identify the sources of nuclear materials using various analytical methods has become a major target of nuclear forensics science. However, despite the emergence of novel tools developed in recent years, it has become obvious that accurate identification of sources requires multiple tools. Here, we have developed a new isotope tool based on Mo isotopes that could be used in nuclear forensics. Molybdenum is a trace element that is found in significant levels in uranium ores (0.5–4800 ppm), uranium minerals (0.02–6000 ppm) and uranium ore concentrates (UOCs, from 0.7 to 1400 ppm). The Mo isotope composition, reported as δ98Mo was analyzed in these materials and shown to have a significant variability from −2.62 to +0.30‰ in uranium ores and from −3.50 to +0.46‰ in UOCs. In uranium ores, the largest Mo isotope fractionation is found in deposits of sedimentary origin while the few ores with a magmatic origin show limited Mo isotope fractionation. Thus, the Mo isotope ratios may ultimately be used to distinguish high temperature from low temperature uranium ores. The δ98Mo values in UOCs also show a significant range that not only originate from variations in ore compositions but can also be attributed to ore processing such as leaching, solvent extraction, resin extraction and UOC precipitation. Laboratory experiments based on existing protocols of uranium ore separation demonstrate the existence of sizeable Mo isotope fractionation associated with these processes. Experiments with solvent extraction and precipitation of ammonium diuranate and peruranate show that the refined uranium fraction is enriched in light Mo isotopes in both cases. In the case of a uranium ore (SOMAÏR, Niger) and associated UOC, the observed fractionation can possibly be assigned to the combined effect of solvent extraction and precipitation, although Mo isotope variability in ores and UOCs may make such a diagnostic difficult. Ultimately, these experiments can be used to reconstruct the Mo isotope composition of the ore, if there is sufficient knowledge about the ore processing flowsheet or to provide information about the type of uranium ore. Alternatively, it could be used to identify the process used for manufacturing a given UOC, if one can make an estimate about the composition of the ore, probably in conjunction with other tools. Our study demonstrates the potential of Mo isotopes as a useful tool in the field of nuclear forensics. [ABSTRACT FROM AUTHOR]

Thorium-230 has many research applications, but there is not a commercial source of this isotope. However, since 230Th is part of the 238U decay chain, it can be separated from naturally occurring uranium. In this work, a novel procedure was developed to separate thorium from uranium ore, consisting of leaching, liquid–liquid extraction, precipitations and ion exchange chromatography. The final product was 91.32 ± 0.77 mg of thorium with a purity of 99.5 ± 1.2 wt%. Of that, 7.65 ± 0.10 mg was 230Th and the remainder 232Th. The total yield of 230Th was 71.1 ± 5.4%. Ways to improve the yield by further processing the back-extraction solution are suggested. [ABSTRACT FROM AUTHOR]

The application of comparator instrumental neutron activation analysis combined with the internal standard method was considered to study rhenium content of the uranium raw material core samples collected in Chu-Sarysu uranium province in the Southern Kazakhstan. Iron content of the samples as the internal comparator was determined by X-ray fluorescence analysis with the help of a laboratory energy dispersive X-ray spectrometer. Rhenium was analyzed by its long-lived radionuclide 186Re using a planar type HPGe detector. Six certified reference materials of complex ores and non-ferrous metal concentrates were analyzed to verify the accuracy of the method. Rhenium and its main interfering elements were determined in the samples from three different sites of the uranium province. Due to reverse correlation dependence, selenium was found as a simple predictor of industrially significant rhenium contents. The method can be used to analyse rhenium mass fractions more than ~0.02 mg/kg in the ores with uranium content of the samples not exceeding several hundreds mg/kg. [ABSTRACT FROM AUTHOR]

Radiation exposure in humans can emanate from natural radionuclides through uranium and thorium decay series as well as40K due to emitted ionising radiations. It is important to estimate the exposure of humans to the diverse sources of radiation. In this study, the activity concentrations of natural radionuclides238U and232Th in granitic rock samples from uranium mine sites in parts of Northern Nigeria were measured, by inductively coupled plasma-mass spectrometry. The highest values of238U and232Th concentrations (924.56 ± 17.13 and 21.96 ± 1.28 Bq/kg, respectively) were observed at Mika-I and Riruwai. Furthermore, the radiological exposure parameters (i.e., absorbed dose rate in air [D], annual effective dose [external], radium equivalent activity (Raeq), external exposure index (Hex), internal exposure index (Hin), and representative level index (Iγand Iα) were estimated and compared to the international recommended values. In terms of terrestrial gamma radiation from granitic rock within the study area, it does not pose any significant radiation exposure to the workers and dwellers. [ABSTRACT FROM AUTHOR]

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A low-grade and permeable sandstone uranium samples in Inner Mongolia prospect, China was subjected to Na2CO3/NaHCO3 leaching. The uranium dissolution mechanism was investigated by effects of leaching parameters and the shrinking core model was selected to model uranium leaching reactions. Agitation leach tests showed that the maximum uranium leaching rate reached 96.5% at 25 °C and had an 19% yield increase when added of 1 mg/L the anionic surfactant to the leaching solution. The optimum process operating parameters were: molar ratio of Na2CO3:NaHCO3 1:1, solid–liquid ratio 1:6, contact time 4 h, agitation speed 400 rpm and the surfactant concentration in leach liquor with 1 mg/L. The kinetics equations indicated that the reactions appear to mix control turn to layer diffusion control with the surfactants adding. [ABSTRACT FROM AUTHOR]

In order to study the radon release behavior when heap leaching uranium ores with dilute sulfuric acid, unleached uranium ores from a uranium mine in southern China were selected as test samples. Adopting parameters from leaching processes commonly used in uranium mines, a laboratory experiment was carried out for 21 days with a one-dimensional acid heap leaching experimental column. The surface radon exhalation rate of uranium ore column was determined by static accumulation method while spraying with deionized water and dilute sulfuric acid. The uranium leaching rate and ore column height for all 21 days of the experiment were also measured. The results show that (1) when sprayed with a leaching agent, the surface radon exhalation rate of uranium ore column initially increased with time sharply. After a maximum value was reached, the rate gradually decreased and stabilized. When the spraying stopped, the surface radon exhalation rate of uranium ore column initially decreased, before increasing until it tended to stabilize. (2) During the entirety of the 21-day leaching experiment, the cumulative leaching rate of uranium increased gradually with time. On the other hand, the surface radon exhalation rate of uranium ore column fluctuated, but the leaching of uranium from uranium ores had almost no effect on the radon exhalation rate. (3) There was no linear correlation between the surface radon exhalation rate and the residual height of ore column during leaching, but the collapsing event of ore column was the direct inducing factor of the fluctuation of surface radon exhalation rate. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • The smaller uranium ore particle size led to the faster leaching rate of uranium. • The maximum uranium extraction was 64.85% with ore particle size of <15 mm. • Uranium bioleaching process followed a diffusion-controlled kinetics model. Abstract This study evaluated the effectiveness of ore particle size on column bioleaching from low-grade uranium ore using an indigenous Acidithiobacillus ferrooxidans , isolated from local uranium ore. The uranium content was 0.033% by weight and ore particle size was crushed to <50 mm, <30 mm, and <15 mm. The additive content of sulfuric acid 5 g/L, Fe3+ dosage of 5.0 g/L, spray strength of 2.57 L/(h·m2) and temperature of 25 °C were controlled. After 150 days of leaching, acid consumption amounted to 2.73 g H 2 SO 4 per kg ore, the obtained maximum uranium extraction was 64.85% with the ore particle size of <15 mm. The results showed that a smaller particle size ore had a higher uranium extraction and that an economic uranium extraction can be obtained by correctly controlling the ore granularity. [ABSTRACT FROM AUTHOR]

Arsenic (As) is often found naturally as the co-contaminant in the uranium (U)-contaminated area, obstructing the bioremediation process. Although the U-contaminated environment harbors microorganisms capable of interacting with U which could be exploited in bioremediation. However, they might be unable to perform with their full potential due to As toxicity. Therefore, potential in arsenic resistance and oxidation is greatly desired among the microorganisms for a continued bioremediation process. In this study, arsenic-resistant bacteria were isolated from U ore collected from Bundugurang U mine, characterized and their As oxidation and U removal potentials were determined. 16S rRNA gene sequencing and phylogenetic analysis showed the affiliation of isolated bacteria with Microbacterium, Micrococcus, Shinella, and Bacillus. Except Bacillus sp. EIKU7, Microbacterium sp. EIKU5, Shinella sp. EIKU6, and Micrococcus sp. EIKU8 were found to resist more than 400 mM As(V); however, all the isolates could survive in 8 mM As(III). The isolates were found to readily oxidize As under different culture conditions and are also resistant towards Cd, Cr, Co, Ni, and Zn. All the isolates could remove more than 350 mg U/g dry cells within 48 h which were found to be highly dependent upon the concentration of U, biomass added initially, and on the time of exposure. Ability of the isolates to grow in nitrogen-free medium indicated that they can flourish in the nutrition deprived environment. Therefore, the recovery of isolates with the potent ability to resist and oxidize As from U ore might play an important role in toxic metal bioremediation including U. [ABSTRACT FROM AUTHOR]