ARTICLE | doi:10.20944/preprints202309.1230.v1
Subject: Engineering, Mining And Mineral Processing Keywords: element concentration–area (C-A); multifractal; singularity exponent; uranium ore; uranium distribution characteristic
Online: 19 September 2023 (13:30:31 CEST)
Based on the analysis of the spatial distribution of uranium grade in 348 boreholes of a uranium deposit in Xinjiang, the enrichment and spatial variation of uranium ore in two stopes of the deposit are discussed by using multifractal theory. The distribution characteristics of uranium ore of the two stopes are studied by multifractal parameters: the scaling exponent of mass , the scaling exponent of each sub-set and its corresponding fractal dimension , the fractal dimension D0 and information dimension D1. The differences of uranium distribution in two stopes can be well quantified by multifractal spectrum and multifractal parameters( , , ).10m×10m is defined as a fence unit, and the window sizes are respectively set, the singularity exponent of the two stopes are calculated by this element concentration-area(C-A) 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 local concentration and spatial variation rules of uranium distribution and the design of the parameters of leaching uranium mining well site.
SHORT NOTE | doi:10.20944/preprints202305.0174.v1
Subject: Physical Sciences, Condensed Matter Physics Keywords: Thorium–Uranium Dioxide; Thorium–Plutonium Dioxide; Uranium–Plutonium Dioxide; Actinide Oxides; Melting; Solidification
Online: 4 May 2023 (03:39:53 CEST)
The article continues the search for a general law that describes the physical properties of a solid body, represented as a complex compound, through the physical properties of its elements. For a set of mixtures of metal oxides (actinide oxides), their melting or solidification temperatures were described in terms of the atomic weighted sum of the melting/solidification temperatures of these metals and molecular oxygen, multiplied by a variable which depending on the crystal structure and properties of melt of the compound and on the atomic numbers of the elements that make up the compound.
ARTICLE | doi:10.20944/preprints202309.1972.v1
Subject: Environmental And Earth Sciences, Pollution Keywords: heavy metals; uranium; contaminated food
Online: 28 September 2023 (10:12:51 CEST)
The rapid technological development of society determined increased demand for safe potable water and food resources. Unfortunately, this progress causes complex environmental pollution, that is continuously challenging the scholars’ community. Therefore, it is important to chemically analyze the food for a better understanding of pollution-spreading mechanisms. Our study is focused on food analysis originating from Vatra Dornei City, which belongs to Suceava County in the Bukovina region of Romania. It represents a well-known Romanian spa and ski resort in the northern parts of the Oriental Carpathians Mountains. The mountain region owns a lot of mineral resources, mainly consisting of mineral and sparkling waters, uranium, manganese, copper, pyrite, chalcopyrite, polymetallic ores, baryte, gold and silver-bearing orebodies, etc. The present contribution aims to point out the results obtained from the analysis of soil, water and food samples collected from the local markets. The food samples consisted of lettuce, spinach, apples, pork (smoked) chicken meat (raw), milk and cheese. Last year the survey was conducted over six months. The results highlighted that the mining activities carried out during time caused environmental pollution with uranium and heavy metals due to the waste heaps’ weathering phenomena and tailing ponds’ presence.
ARTICLE | doi:10.20944/preprints202211.0288.v1
Subject: Environmental And Earth Sciences, Environmental Science Keywords: radium; uranium; groundwater; interlaboratory comparison
Online: 15 November 2022 (11:04:44 CET)
226Ra and 228Ra are typically monitored for groundwater and surface water compliance at legacy U mining and milling sites. Groundwater monitoring results for combined Ra (226Ra+228Ra) reported by the existing contract laboratory at a former U mine and mill Site (Wyoming, USA) have been highly variable and with increasing trends at the Site compliance and background wells since the method was changed in 2005. Sample reanalysis has indicated poor reproducibility and significant analytical error in 228Ra measurements. An interlaboratory comparison was conducted to evaluate the potential causes of the high variability and analytical error. Two different methods were used for 226Ra (M903.0 and M903.1) and 228Ra (M904.0 and Ra-05). 226Ra results were less variable compared to 228Ra, and 228Ra data from the existing laboratory were qualified as estimated with high bias due to detection of 228Ra in the field blank. Compliance with the 226Ra+228Ra groundwater standard was either met or not met, depending on which laboratory conducted the analyses. Specific laboratory techniques, rather than the analytical method, are contributing to elevated 228Ra values being reported. It was recommended that samples whose 226Ra+228Ra results exceed the Site standard in the future be reanalyzed by the existing laboratory with a sample split also being sent to an outside laboratory for confirmatory analysis.
SHORT NOTE | doi:10.20944/preprints202303.0403.v1
Subject: Physical Sciences, Thermodynamics Keywords: Zirconium carbide; Zirconium nitride; Uranium nitride; Thorium nitride; Uranium carbide; rational numbers; thermal conductivity
Online: 22 March 2023 (15:24:16 CET)
Using number theory, a formula is obtained that describes the thermal conductivities of ZrC, UC, UN, ThN, ZrN and ThxU1-xN at x = 0.2 and 0.5 with temperature change. This formula contains the atomic numbers of the elements, the thermal conductivities of the individual elements of the substance, and the structural parameter. There is no direct dependence on temperature in the formula, since it is hidden in the thermal conductivities of each element and in the structure parameter. In some temperature ranges, the structural parameter is constant; therefore, the thermal conductivity of some carbides and nitrides is expressed through summing the thermal conductivities of individual elements.
ARTICLE | doi:10.20944/preprints201711.0032.v1
Subject: Environmental And Earth Sciences, Environmental Science Keywords: geology; radioactivity; uranium; sampling; Stara Planina
Online: 6 November 2017 (05:13:50 CET)
Stara Planina is known for numerous occurrences and deposits of uranium and associated radionuclides. It is also famous for its geodiversity. The geologic framework is highly complex. The mountain is situated between the latitudes of 43° and 44° N and the longitudes from 22°16′ to 23°00′ E. Uranium exploration and radioactivity testing on Stara Planina began back in 1948. Uranium has also been mined in the zone of Kalna, within the Janja granite intrusive. The naturally-radioactive geologic units of Stara Planina are presented in detail in the paper.
ARTICLE | doi:10.20944/preprints202208.0077.v3
Subject: Environmental And Earth Sciences, Environmental Science Keywords: Uranium; Groundwater; Colorado Plateau; Navajo Nation; Chinle Formation
Online: 7 July 2023 (05:29:53 CEST)
Uranium (U) is enriched in the waters of the southern Colorado Plateau, including waters of the Navajo Nation. The region has naturally occurring U in rocks and a history of U mining which may increase U concentrations in waters. Despite prior research into the concentration of U in the waters of the Navajo Nation, a framework has not been established to understand the variation of U in the region’s groundwater. To this end, we examined data from five studies to establish where and why U is likely to be enriched in waters of the southern Colorado Plateau. We show that U concentrations are related to the presence of U-rich rock bodies, surface elevation, and local aquifer salinity. Additionally, we show that the distance to the nearest mine is a significant predictor of U in water sources. Our work can act as a guide for local water withdrawal, regional water remediation and mitigation efforts, and provides a means for understanding the geographical patterns of U concentration in waters of the southern Colorado Plateau.
ARTICLE | doi:10.20944/preprints201911.0110.v1
Subject: Environmental And Earth Sciences, Environmental Science Keywords: partial extraction; mineral phases; uranium; disequilibrium; retardation factor
Online: 10 November 2019 (13:26:04 CET)
A partial extraction procedure was used to study the distribution of uranium in the mineral phases of rocks of an aquifer of sandy-clay deposits of the Vendian in the northwest of Russia. This work is a part of a research project to develop a method for combined radiocarbon and uranium-isotope dating of groundwater. Representative aliquots of each core sample were subjected to five "partial" extractions by treatment with: distilled water, low mineralized fresh natural groundwater, minopolycarboxylic acid chelating agent (0.05M EDTA), 0.5M HCl, 15M HNO3, and a total digestion, with U isotopes reported in this study for each procedure. The following mineral phases of core samples: adsorbed material, carbonate minerals, amorphous iron oxides, aluminosilicates partial digestion and a crystalline iron oxides, aluminosilicates total digestion and a clay/quartz resistate were characterized. Red-colored siltstones depleted in uranium in relatively readily soluble mineral phases. The concentration of adsorbed uranium was established in the amount of 15.8±2.1 - 30.5±3.9 μg/kg. Carbonate minerals contain even less of this element. In iron hydroxides and the most readily soluble aluminosilicates, its concentrations are in the range 168±24 - 212±28 μg/kg. The most insoluble fraction contains 1.65±0.21 - 4.32±0.45 mg/kg of uranium. In green-colored siltstones, the concentration of adsorbed uranium is much higher: 106±14 - 364±43 μg/kg. Carbonate minerals and amorphous iron oxides contain 1.91±0.21 - 2.34±0.26 mg/kg of uranium. In aluminosilicates and a clay/quartz resistate, uranium concentrations are 5.6±0.5 - 16.8±1.4 mg/kg. Elevated values of 234U:238U activity ratio prevail in the adsorbed material and iron hydroxides. In aluminosilicates and clay/quartz resistate, the values decrease. This indicates the replacement of primary sedimentogenic uranium by secondary hydrogenic uranium adsorbed on the surface of minerals and coprecipitated with iron hydroxides. The results obtained made it possible to carry out preliminary quantitative estimates of the retardation factor and recoil loss factor of uranium in the groundwater of siltstones of the studied Vendian aquifer.
REVIEW | doi:10.20944/preprints202212.0192.v1
Subject: Chemistry And Materials Science, Applied Chemistry Keywords: aerogels; environmental remediation; uranium adsorption; environmental water decontamination; adsorption thermodynamics and kinetics; extraordinary adsorption capacity; qmax values; competitive ions; material recycling; uranium recovery
Online: 12 December 2022 (04:06:36 CET)
Aerogel-based adsorbents present extraordinary sorption capacity for hexavalent uranium that can be as high as 8.8 mol kg–1 (2088 g kg–1). The adsorption data follow generally the Langmuir isotherm model and the kinetic data are better described by the pseudo-second-order kinetic model, which is associated with chemisorption. Evaluation of the thermodynamic data reveals that the adsorption is generally an endothermic, entropy-driven process (ΔHo, ΔSo > 0). Spectroscopic studies (e.g., FTIR, XPS) indicate that the adsorption is based on the formation of in-ner-sphere complexes between surface active moieties and the uranyl cation. Regeneration and uranium recovery by acidification and complexation using carbonate or chelating ligands (e.g., EDTA) have been found to be successful. The application of aerogel-based adsorbents to uranium removal from industrial processes and uranium-contaminated waste waters was also successful, assuming that these materials could be very attractive as adsorbents in water treatment and uranium recovery technologies. However, the selectivity of the studied materials towards hexavalent uranium is limited suggesting further development of aerogel materials which could be modified by surface derivatization with chelating agents (e.g., salophen, iminodiacetate) presenting high selectivity for uranyl moieties.
ARTICLE | doi:10.20944/preprints202105.0743.v1
Subject: Physical Sciences, Acoustics Keywords: PERALS; alpha spectrometry; Polonium; Radon; Radium; Radiostrontium; Thorium; Uranium; Actinides
Online: 31 May 2021 (11:16:23 CEST)
In this paper, experiences of the last 20 years with the PERALS-technique are described. PERALS stands for Photo Electron Rejecting Alpha Liquid Scintillation. This LSC-technique was developed by Jack McDowell in the 70ies and is a powerful technique for the analyses of many natural alpha nuclides. The principle is based on a selective extraction of the radionuclide from the water phase by means of a complexing or ion pair reagent. The extractant contains also a suitable cocktail for the scintillation counting. Therefore, the extract can be analysed directly after the extraction step. After removing quenchers, such as oxygen, and the proper setting of a pulse shape discriminator, alpha pulses can be counted with a photomultiplier. The paper describes the development of robust analysis schemes for the determination of traces of polonium, radon, radium, strontium, thorium, uranium and other actinides in water samples (groundwater, rain water, river water, drinking water, mineral water, sea water).
ARTICLE | doi:10.20944/preprints202310.1980.v1
Subject: Environmental And Earth Sciences, Pollution Keywords: Uranium; In-situ leaching; Reactive transport model; Capture zone; Streamline; pollution control
Online: 31 October 2023 (08:12:28 CET)
Acid in-situ leaching (ISL) is a common approach to the recovery of uranium in the subsurface. As some toxic and harmful substances might be produced by the chemical reactions among the injected sulphuric acid, the groundwater, and the porous media during leaching processes, the pollution control of the mining plan for ISL is important. In this study, a three-dimensional reactive transport modeling (3DRTM) was applied to decide the pollution control mining plan, considering the partial penetration through wellbore in confined aquifer and complex chemical reactions between main minerals. Based on the 3DRTM, different pumping ratio and non-uniform injection schemes were compared. The results show that the preferential pollution control mining plan is non-uniform injection ratio equal 0.1. By analyzing the characteristics of water table and streamline, it is concluded that the scheme has a strong hydraulic capture effect. In this scheme, the concentration of UO22+, H+, SO42- obtained by 3DRTM is lower. The inner well injection rate is 194.09 m3/d, the outer well injection rate is 158.89 m3/d, and the pumping rate is 264.00 m3/d. A reasonable suggestion is to adopt non-uniform injection mining mode in ISL.
ARTICLE | doi:10.20944/preprints202306.0870.v1
Subject: Environmental And Earth Sciences, Geochemistry And Petrology Keywords: Southern Margin of North China Craton; Xiaoqinling; Huayangchuan; Uranium; Pegmatite; Paleoproterozoic; Mineralization age
Online: 13 June 2023 (03:31:13 CEST)
The Huayangchuan uranium deposit, located in the west of the Xiaoqinling belt on the southern margin of the North China Craton, is a polymetallic deposit dominated by U, Nb, Pb, and rare earth elements. The Huayangchuan uranium deposit, discovered in the 1950s, has long been known as a carbonatite-type uranium deposit. Recently, new geological work has found uranium mineralisation in many granitic pegmatite veins in the Huayangchuan deposit and adjacent areas. Here, we report a systematic investigation of the petrography, whole-rock geochemistry, zircon U-Pb ages, and in situ Lu-Hf isotopic characteristics of newly discovered U-rich granitic pegmatite veins in the west of Huayangchuan deposit. The petrological results showed that the lithology of the samples is equivalent to that of granite. The U-Pb ages of zircon were 1826.3 ± 7.9 and 1829 ± 11 Ma. Microscopically, the symbiotic characteristics of zircon, betafite, and uraninite exist in the intergranular fissures of K-feldspar and quartz, reflecting metallogenic phenomena in the rock formation process. Almost all whole-rock samples were rich in SiO2 (64.37–70.69 wt.%), total alkalis (K2O+Na2O = 8.50–10.30 wt.%), and Al2O3 (12.20–14.41 wt.%), but poor in Ti2O (0.23–0.73 wt.%), MgO (0.38–0.90 wt.%), P2O5 (0.14–0.83 wt.%), MnO (0.04–0.57 wt.%). Additionally, they showed enrichment of LILEs (such as Rb, Ba, Th, U, and K), depletion of HFSEs (such as Ta, Nb, P, Ti, and Hf), no alkaline dark minerals, and the characteristics are typical of intraplate A1-type granite. The A1-type granite displayed low zircon εHf(t) values (-19.42– -15.02) with zircon two-stage Hf model aged 3.10–2.76 Ga, indicating that the U-rich granitic pegmatite was derived predominantly from partial melting of the ancient continental crust (such as the early Taihua group formed in Archean-Neoarchean). Combined with the above results and regional geological data, the U-rich granitic pegmatite discovered in the Huayangchuan deposit was related to granite magma activity that formed in a post-collisional regime after the Luliang movement in the late Palaeoproterozoic. This study suggests that future uranium prospecting work in this area should focus on late Palaeoproterozoic U-rich granitic pegmatites.
ARTICLE | doi:10.20944/preprints202302.0343.v1
Subject: Chemistry And Materials Science, Medicinal Chemistry Keywords: targeted alpha therapy; alpha-emitter; thorium-226; uranium-230; isotope generator; extraction chromatography
Online: 20 February 2023 (14:17:58 CET)
A unique two-column 230U/226Th generator has been developed. The focus was hold on obtaining 226Th of high purity in a solution amenable to further labeling. The first column of the proposed generator filled with TEVA Resin held 230U, from which 226Th was eluted with 7 M HCl solution. UTEVA Resin pretreated with nitric acid solution was used as a sorbent for the second column for thorium retention. 226Th was extracted with 0.01-0.05 M citric buffer solution. One cycle of generator milking took 5-7 minutes and produced > 90% of 226Th in 1.5 ml of eluate, pH 4.5-5.0. The proposed two-column 230U/226Th generator was tested over two months including a second loading of 230U additionally accumulated from 230Pa. The 230U impurity in 226Th eluate was less than 0.01% allowing to use it directly in synthesis of radiopharmaceutical compounds.
ARTICLE | doi:10.20944/preprints201805.0255.v1
Subject: Chemistry And Materials Science, Inorganic And Nuclear Chemistry Keywords: magnesium potassium phosphate compound; actinides; rare earth elements; uranium; plutonium; americium; lanthanum; neodymium; immobilization; leaching
Online: 18 May 2018 (06:13:11 CEST)
The problem of effective immobilization of liquid radioactive waste (LRW) is key to the successful development of nuclear energy. The possibility of using magnesium potassium phosphate (MKP) compound for LRW immobilization on the example of nitric acid solutions containing actinides and rare earth elements (REE), including high level waste (HLW) surrogate solution is considered in the research work. Under the study of phase composition and structure of the MKP compounds obtained by the XRD and SEM methods, it was established that the compounds are composed of crystalline phases - analogues of natural phosphate minerals (struvite, metaankoleite). The hydrolytic stability of the compounds was determined according to the semi-dynamic test GOST R 52126-2003. Low leaching rates of radionuclides from the compound are established, including a differential leaching rate of 239Pu and 241Am - 3.5 × 10-7 and 5.3 × 10-7 g/(cm2∙day). As a result of the research work it was concluded that the MKP compound is promising for LRW immobilization and can become an alternative material combining the advantages of easy implementation of the technology like cementation and the high physical and chemical stability corresponding to a glass-like compound.
ARTICLE | doi:10.20944/preprints202304.1211.v1
Subject: Chemistry And Materials Science, Nanotechnology Keywords: Uranyl Cations; Dendritic Polymers; Silica Xerogels; Composites; Nanoparticles; water purification; radioactive wastewater; Uranium removal; Dendrimers; Biomimetic
Online: 29 April 2023 (04:48:19 CEST)
Two different silica conformations (Xerogels and Nanoparticles) both formed by the mediation of dendritic poly (ethylene imine) were tested at low pHs on the problematic uranyl cation sorption. The effect of crucial factors i.e., temperature, electrostatic forces, adsorbent composition, accessibility of the pollutant to the dendritic cavities and MW of the organic matrix was investigated to conclude the optimum formulation for water purification under these conditions. This was attained with the aid of UV-Visible and FTIR spectroscopy, dynamic light scattering (DLS), ζ-potential; Brunauer–Emmett–Teller (BET) porosimetry, Thermo Gravimetric Analysis (TG) and Scanning Electron Microscopy (SEM) Results highlighted that both adsorbents have extraordinary sorp-tion capacity. Xerogels are cost-effective since they approximate the performance of na-noparticles with much lesser organic content. Furthermore, they are more practicable materials since they may penetrate the pores of a metal or ceramic solid substrate in the form of a precursor, gel-forming solution.
ARTICLE | doi:10.20944/preprints202212.0530.v1
Subject: Physical Sciences, Atomic And Molecular Physics Keywords: generalized relativistic pseudopotentials; molecular integrals; Gaussian basis functions; relativistic coupled cluster theory; excited states; heavy-element compounds; high-precision electronic structure modeling; thorium oxide; uranium dioxide.
Online: 28 December 2022 (07:57:51 CET)
Generalized relativistic pseudopotentials (GRPP) of atomic cores implying the use of different potentials for atomic electronic shells with different principal quantum numbers give rise to accurate and reliable relativistic electronic structure models of atoms, molecules, clusters, and solids. These models readily incorporate the effects of Breit electron-electron interactions and one-loop quantum electrodynamics effects. Here we report the computational procedure for evaluating one-electron integrals of GRPP over contracted Gaussian functions. This procedure was implemented in a library of routines named LIBGRPP, which can be integrated into existing quantum chemistry software, thus enabling the application of various methods to solve the many-electron problem with GRPPs. Pilot applications to electronic transitions in the ThO and UO2 molecules using the new library and intermediate-Hamiltonian Fock space relativistic coupled cluster method are presented. The results clearly demonstrate that rather economical tiny-core GRPP models can exceed in accuracy relativistic all-electron models defined by Dirac-Coulomb and Dirac-Coulomb-Gaunt Hamiltonians.