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Sample records for autunite

  1. Investigation on Microbial Dissolution of Uranium (VI) from Autunite Mineral - 13421

    International Nuclear Information System (INIS)

    Sepulveda, Paola; Katsenovich, Yelena; Lagos, Leonel

    2013-01-01

    Precipitating autunite minerals by polyphosphate injection was identified as a feasible remediation strategy for sequestering uranium in contaminated groundwater and soil in situ at the Hanford Site. Autunite stability under vadose and saturated zone environmental conditions can help to determine the long-term effectiveness of this remediation strategy. The Arthrobacter bacteria are one of the most common groups in soils and are found in large numbers in Hanford soil as well as other subsurface environments contaminated with radionuclides. Ubiquitous in subsurface microbial communities, these bacteria can play a significant role in the dissolution of minerals and the formation of secondary minerals. The main objective of this investigation was to study the bacterial interactions under oxidizing conditions with uranium (VI); study the potential role of bicarbonate, which is an integral complexing ligand for U(VI) and a major ion in groundwater compositions; and present data from autunite dissolution experiments using Arthrobacter strain G968, a less U(VI)-tolerant strain. Sterile 100 mL glass mixed reactors served as the major bioreactor for initial experimentation. These autunite-containing bioreactors were injected with bacterial cells after the autunite equilibrated with the media solution amended with 0 mM, 3 mM 5 mM and 10 mM concentrations of bicarbonate. G968 Arthrobacter cells in the amount of 10 6 cells/mL were injected into the reactors after 27 days, giving time for the autunite to reach steady state. Abiotic non-carbonate controls were kept without bacterial inoculation to provide a control for the biotic samples. Samples of the solution were analyzed for dissolved U(VI) by means of kinetic phosphorescence analyzer KPA-11 (Chemcheck Instruments, Richland, WA). Analysis showed that as [HCO 3 - ] increases, a diminishing trend on the effect of bacteria on autunite leaching is observed. Viability of cells was conducted after 24 hours of cell incubation with

  2. Investigation on Microbial Dissolution of Uranium (VI) from Autunite Mineral - 13421

    Energy Technology Data Exchange (ETDEWEB)

    Sepulveda, Paola; Katsenovich, Yelena; Lagos, Leonel [Applied Research Center, Florida International University. 10555 West Flagler St. Suite 2100, Miami Fl 33175 (United States)

    2013-07-01

    Precipitating autunite minerals by polyphosphate injection was identified as a feasible remediation strategy for sequestering uranium in contaminated groundwater and soil in situ at the Hanford Site. Autunite stability under vadose and saturated zone environmental conditions can help to determine the long-term effectiveness of this remediation strategy. The Arthrobacter bacteria are one of the most common groups in soils and are found in large numbers in Hanford soil as well as other subsurface environments contaminated with radionuclides. Ubiquitous in subsurface microbial communities, these bacteria can play a significant role in the dissolution of minerals and the formation of secondary minerals. The main objective of this investigation was to study the bacterial interactions under oxidizing conditions with uranium (VI); study the potential role of bicarbonate, which is an integral complexing ligand for U(VI) and a major ion in groundwater compositions; and present data from autunite dissolution experiments using Arthrobacter strain G968, a less U(VI)-tolerant strain. Sterile 100 mL glass mixed reactors served as the major bioreactor for initial experimentation. These autunite-containing bioreactors were injected with bacterial cells after the autunite equilibrated with the media solution amended with 0 mM, 3 mM 5 mM and 10 mM concentrations of bicarbonate. G968 Arthrobacter cells in the amount of 10{sup 6} cells/mL were injected into the reactors after 27 days, giving time for the autunite to reach steady state. Abiotic non-carbonate controls were kept without bacterial inoculation to provide a control for the biotic samples. Samples of the solution were analyzed for dissolved U(VI) by means of kinetic phosphorescence analyzer KPA-11 (Chemcheck Instruments, Richland, WA). Analysis showed that as [HCO{sub 3}{sup -}] increases, a diminishing trend on the effect of bacteria on autunite leaching is observed. Viability of cells was conducted after 24 hours of cell

  3. Enhanced U(VI) release from autunite mineral by aerobic Arthrobacter sp. in the presence of aqueous bicarbonate

    Energy Technology Data Exchange (ETDEWEB)

    Katsenovich, Yelena P.; Carvajal, Denny A.; Wellman, Dawn M.; Lagos, Leonel E.

    2012-05-01

    The bacterial effect on U(VI) release from the autunite mineral (Ca[(UO2)(PO4)]2•3H2O) was investigated to provide a more comprehensive understanding of the important microbiological processes affecting autunite stability within subsurface bicarbonate-bearing environments. Experiments were performed in a culture of the Arthrobacter oxydans G975 strain, herein referred to as G975, a soil bacterium previously isolated from Hanford Site soil. 91 mg of autunite powder and 50 mL of phosphorous-limiting sterile media were amended with bicarbonate (ranging between 1 and 10 mM) in glass reactor bottles and inoculated with the G975 strain after the dissolution of autunite was at steady state. SEM observations indicated that G975 formed a biofilm on the autunite surface and penetrated the mineral cleavages. The mineral surface colonization by bacteria tended to increase concomitantly with bicarbonate concentrations. Additionally, a sterile culture-ware with inserts was used in non-contact dissolution experiments where autunite and bacteria cells were kept separately. The data suggest that G975 bacteria is able to enhance the release of U(VI) from autunite without direct contact with the mineral. In the presence of bicarbonate, the damage to bacterial cells caused by U(VI) toxicity was reduced, yielding similar values for total organic carbon (TOC) degradation and cell density compared to U(VI)-free controls. The presence of active bacterial cells greatly enhanced the release of U(VI) from autunite in bicarbonate-amended media.

  4. Enhanced U(VI) release from autunite mineral by aerobic Arthrobacter sp. in the presence of aqueous bicarbonate

    Energy Technology Data Exchange (ETDEWEB)

    Katsenovich, Yelena; Carvajal, Denny A.; Wellman, Dawn M.; Lagos, Leonel

    2012-04-20

    The bacterial effect on U(VI) leaching from the autunite mineral (Ca[(UO{sub 2})(PO{sub 4})]{sub 2} {center_dot} 3H{sub 2}O) was investigated to provide a more comprehensive understanding into important microbiological processes affecting autunite stability within subsurface bicarbonate-bearing environments. Experiments were performed in a culture of G975 Arthrobacter oxydans strain, herein referred to as G975, a soil bacterium previously isolated from Hanford Site soil. 91 mg of autunite powder and 50 mL of phosphorus-limiting sterile media were amended with bicarbonate ranging between 1-10 mM in glass reactor bottles and inoculated with G975 strain after the dissolution of autunite was at steady state. SEM observations indicated G975 formed a biofilm on the autunite surface and penetrated the mineral cleavages. The mineral surface colonization by bacteria tended to increase concomitantly with bicarbonate concentrations. Additionally, a sterile cultureware with inserts was used in non-contact bioleaching experiments where autunite and bacteria cells were kept separately. The data suggest the G975 bacteria is able to enhance U(VI) leaching from autunite without the direct contact with the mineral. In the presence of bicarbonate, the damage to bacterial cells caused by U(VI) toxicity was reduced, yielding similar values for total organic carbon (TOC) degradation and cell density compared to U(VI)-free controls. The presence of active bacterial cells greatly enhanced the U(VI) bioleaching from autunite in bicarbonate-amended media.

  5. Crystal structure of bassetite and saleeite. New insight into autunite-group minerals

    Energy Technology Data Exchange (ETDEWEB)

    Dal Bo, Fabrice; Hatert, Frederic [Liege Univ. (Belgium). Lab. de Mineralogie; Mees, Florias [Royal Museum for Central Africa, Tervuren (Belgium); Philippo, Simon [Musee National d' Histoire Naturelle, Luxembourg (Luxembourg). Section Mineralogie; Baijot, Maxime; Fontaine, Francois [Liege Univ. (Belgium). Dept. de Geologie

    2016-06-15

    The crystal structures of two autunite-group minerals have been solved recently. The crystal structure of bassetite, Fe{sup 2+}[(UO{sub 2})(PO{sub 4})]{sub 2}(H{sub 2}O){sub 10}, from the type locality in Cornwall, United Kingdom (Basset Mines) was solved for the first time. Bassetite is monoclinic, space group P2{sub 1}/n, a = 6.961(1), b = 20.039(2), c = 6.974(1) Aa and β = 90.46(1) . The crystal structure of saleeite, Mg[(UO{sub 2})(PO{sub 4})]{sub 2}(H{sub 2}O){sub 10}, from Shinkolobwe, Democratic Republic of Congo, was also solved. Saleeite is monoclinic, space group P2{sub 1}/n, a = 6.951(1), b = 19.942(1), c = 6.967(1) Aa and β = 90.58(1) . The crystal structure investigation of bassetite (R{sub 1} = 0.0658 for 1879 observed reflections with vertical stroke F{sub o} vertical stroke ≥ 4σ{sub F}) and saleeite (R{sub 1} = 0.0307 for 1990 observed reflections with vertical stroke F{sub o} vertical stroke ≥ 4σ{sub F}) confirms that both minerals are topologically identical and that bassetite contains ten water molecules per formula unit. Their structure contains autunite-type sheets, [(UO{sub 2})(PO{sub 4})]{sup -}, consisting of corner-sharing UO{sub 6} square bipyramids and PO{sub 4} tetrahedra. Iron and magnesium are surrounded by water molecules to form Fe(H{sub 2}O){sub 6} or Mg(H{sub 2}O){sub 6} octahedra located in interlayer, between the autunite-type sheets. Two isolated independent water molecules are also located in interlayer. Energy-dispersive X-ray spectroscopy analysis confirmed the chemical composition obtained from structure refinement. These new data prompt a re-assessment of minerals of the autunite and meta-autunite groups.

  6. The Effect of Bicarbonate on the Microbial Dissolution of Autunite Mineral in the Presence of Gram-Positive Bacteria

    Energy Technology Data Exchange (ETDEWEB)

    Sepulveda-Medina, Paola; Katsenovich, Yelena; Wellman, Dawn M.; Lagos, Leonel

    2015-06-01

    Bacteria are key players in the processes that govern fate and transport of contaminants. The uranium release from Na and Ca-autunite by Arthrobacter oxydans strain G968 was evaluated in the presence of bicarbonate ions. This bacterium was previously isolated from Hanford Site soil and in earlier prescreening tests demonstrated low tolerance to U(VI) toxicity compared to other A.oxydans isolates. Experiments were conducted using glass serum bottles as mixed bioreactors and sterile 6-well cell culture plates with inserts separating bacteria cells from mineral solids. Reactors containing phosphorus-limiting media were amended with bicarbonate ranging between 0-10 mM and metaautunite solids to provide a U(VI) concentration of 4.4 mmol/L. Results showed that in the presence of bicarbonate, A.oxydans G968 was able to enhance the release of U(VI) from Na and Ca autunite at the same capacity as other A.oxydans isolates with relatively high tolerance to U(VI). The effect of bacterial strains on autunite dissolution decreases as the concentration of bicarbonate increases. The results illustrate that direct interaction between the bacteria and the mineral is not necessary to result in U (VI) biorelease from autunite. The formation of secondary calcium-phosphate mineral phases on the surface of the mineral during the dissolution can ultimately reduce the natural autunite mineral contact area, which bacterial cells can access. This thereby reduces the concentration of uranium released into the solution. This study provides a better understanding of the interactions between meta-autunite and microbes in conditions mimicking arid and semiarid subsurface environments of western U.S.

  7. Natural attenuation of uranium and formation of autunite at the expense of apatite within an oxidizing environment, south Eastern Desert of Egypt

    International Nuclear Information System (INIS)

    Abd El-Naby, Hamdy H.; Dawood, Yehia H.

    2008-01-01

    X-ray diffraction (XRD), back scattered electron imaging (BSE), wavelength-dispersion spectral scan (WDS), X-ray compositional mapping and quantitative electron probe micro analyses (EPMA) have been used to examine a natural attenuation of U during low temperature alteration of the Sela granite, south Eastern Desert of Egypt. The data confirmed that a pre-existing hydroxyapatite was transformed to autunite through an unidentified intermediate phase. The boundaries between these three phases are not sharp and are generally interfering indicative of the replacement of Ca by U. The hydroxyapatite, intermediate phase and autunite show similar chondrite normalized rare earth elements (REE) patterns suggesting a genetic relationship. Alteration processes have enriched the three phases with heavy rare earth elements (HREE) and Eu and caused Ce, Dy and Yb negative anomalies. Based on the pH of the aqueous solutions, two mechanisms may explain the conversion of hydroxyapatite to autunite: (1) the dissolution of hydroxyapatite and precipitation of autunite which would happen when the uranyl bearing solutions were acidic enough (pH = 3-6.8) to be able to dissolve the pre-existing hydroxyapatite and (2) sorption of the uranyl ion on the surface of hydroxyapatite followed by substitution of (UO 2 ) 2+ at the expense of Ca 2+ . The latter mechanism would have happened if the pH of the aqueous solutions were near neutral and at low dissolved concentrations of uranyl ion. The genesis of uranyl mineralization in the Sela area supports the use of apatite-based technologies for U remediation in an oxidizing environment

  8. Quantification of Kinetic Rate Law Parameters of Uranium Release from Sodium Autunite as a Function of Aqueous Bicarbonate Concentrations

    Energy Technology Data Exchange (ETDEWEB)

    Gudavalli, Ravi; Katsenovich, Yelena; Wellman, Dawn M.; Lagos, Leonel; Tansel, Berrin

    2013-09-05

    ABSTRACT: Hydrogen carbonate is one of the most significant components within the uranium geochemical cycle. In aqueous solutions, hydrogen carbonate forms strong complexes with uranium. As such, aqueous bicarbonate may significantly increase the rate of uranium release from uranium minerals. Quantifying the relationship of aqueous hydrogen carbonate solutions to the rate of uranium release during dissolution is critical to understanding the long-term fate of uranium within the environment. Single-pass flow-through (SPTF) experiments were conducted to estimate the rate of uranium release from Na meta-autunite as a function of bicarbonate solutions (0.0005-0.003 M) under the pH range of 6-11 and temperatures of 5-60oC. Consistent with the results of previous investigation, the rate of uranium release from sodium autunite exhibited minimal dependency on temperature; but were strongly dependent on pH and increasing concentrations of bicarbonate solutions. Most notably at pH 7, the rate of uranium release exhibited 370 fold increases relative to the rate of uranium release in the absence of bicarbonate. However, the effect of increasing concentrations of bicarbonate solutions on the release of uranium was significantly less under higher pH conditions. It is postulated that at high pH values, surface sites are saturated with carbonate, thus the addition of more bicarbonate would have less effect on uranium release. Results indicate the activation energies were unaffected by temperature and bicarbonate concentration variations, but were strongly dependent on pH conditions. As pH increased from 6 to 11, activation energy values were observed to decrease from 29.94 kJ mol-1 to 13.07 kJ mol-1. The calculated activation energies suggest a surface controlled dissolution mechanism.

  9. Comparison of the Kinetic Rate Law Parameters for the Dissolution of Natural and Synthetic Autunite in the Presence of Aqueous Bicarbonate Ions

    Energy Technology Data Exchange (ETDEWEB)

    Gudavalli, Ravi; Katsenovich, Yelena; Wellman, Dawn M.; Idarraga, Melina; Lagos, Leonel; Tansel, Berrin

    2013-08-02

    Bicarbonate is one of the most significant components within the uranium geochemical cycle. In aqueous solutions, bicarbonate forms strong complexes with uranium. As such, aqueous bicarbonate may significantly increase the rate of uranium release from uranium minerals. Quantifying the relationship of aqueous bicarbonate concentration to the rate of uranium release during dissolution is critical to understanding the long-term fate of uranium within the environment. Single-pass flow-through (SPTF) experiments were conducted to estimate the rate of uranium release from Na meta-autunite as a function of bicarbonate (0.0005-0.003 M) under the pH range of 6-11 and a temperature range of 5-60oC. Consistent with the results of previous investigation, the rate of uranium release exhibited minimal dependency on temperature; but were strongly dependent on pH. Increasing aqueous bicarbonate concentrations afforded comparable increases in the rate of release of uranium. Most notably under low pH conditions the aqueous bicarbonate resulted in up to 370 fold increases in the rate of uranium release in relative to the rate of uranium release in the absence of bicarbonate. However, the effect of aqueous bicarbonate on the release of uranium was significantly less under higher pH conditions. It is postulated that at high pH values, surface sites are saturated with carbonate, thus the addition of more bicarbonate would have less effect on uranium release.

  10. 300 Area Uranium Stabilization Through Polyphosphate Injection: Final Report

    Energy Technology Data Exchange (ETDEWEB)

    Vermeul, Vincent R.; Bjornstad, Bruce N.; Fritz, Brad G.; Fruchter, Jonathan S.; Mackley, Rob D.; Newcomer, Darrell R.; Mendoza, Donaldo P.; Rockhold, Mark L.; Wellman, Dawn M.; Williams, Mark D.

    2009-06-30

    The objective of the treatability test was to evaluate the efficacy of using polyphosphate injections to treat uranium-contaminated groundwater in situ. A test site consisting of an injection well and 15 monitoring wells was installed in the 300 Area near the process trenches that had previously received uranium-bearing effluents. This report summarizes the work on the polyphosphate injection project, including bench-scale laboratory studies, a field injection test, and the subsequent analysis and interpretation of the results. Previous laboratory tests have demonstrated that when a soluble form of polyphosphate is injected into uranium-bearing saturated porous media, immobilization of uranium occurs due to formation of an insoluble uranyl phosphate, autunite [Ca(UO2)2(PO4)2•nH2O]. These tests were conducted at conditions expected for the aquifer and used Hanford soils and groundwater containing very low concentrations of uranium (10-6 M). Because autunite sequesters uranium in the oxidized form U(VI) rather than forcing reduction to U(IV), the possibility of re-oxidation and subsequent re-mobilization is negated. Extensive testing demonstrated the very low solubility and slow dissolution kinetics of autunite. In addition to autunite, excess phosphorous may result in apatite mineral formation, which provides a long-term source of treatment capacity. Phosphate arrival response data indicate that, under site conditions, the polyphosphate amendment could be effectively distributed over a relatively large lateral extent, with wells located at a radial distance of 23 m (75 ft) reaching from between 40% and 60% of the injection concentration. Given these phosphate transport characteristics, direct treatment of uranium through the formation of uranyl-phosphate mineral phases (i.e., autunite) could likely be effectively implemented at full field scale. However, formation of calcium-phosphate mineral phases using the selected three-phase approach was problematic. Although

  11. Polyphosphate Amendments for In-Situ Immobilization of Uranium Plumes

    International Nuclear Information System (INIS)

    Wellman, Dawn M.; Icenhower, Jonathan P.; Pierce, Eric M.; McNamara, Bruce K.; Burton, Sarah D.; Geiszler, Keith N.; Baum, Steven R.; Butler, Bart C.; R.F. Olfenbuttel; P.J. White

    2005-01-01

    A multi-faceted approach has been taken to address basic science questions with regards to the efficacy of utilizing phosphate amendments for subsurface immobilization of uranium plumes. Hydraulically saturated and unsaturated column tests demonstrate the ability of polyphosphate compounds to control the precipitation kinetics of insoluble phosphate minerals and optimize conditions for controlled application of phosphate amendments for subsurface remediation. X-Ray micro-focus tomography results illustrate long-term effects of phosphate mineralization on hydraulic conductivity. 31P NMR has been utilized to quantify the effect of sedimentary and aqueous components on the in-situ hydrolysis kinetics of condensed polyphosphates. Single-pass flow-through (SPFT) tests have been conducted to evaluate the longevity and quantify the effects of aqueous organic material on the dissolution kinetics of autunite minerals, X1-2[(UO2)(PO4)]2nH2O. Preliminary results indicate: (1) autunite minerals will precipitate within 1-2 months given a 0.05 M phosphate concentration and 10-6 M aqueous uranium concentration, under hydraulically saturated conditions; (2) polyphosphate chain lengths can be optimized for specific site conditions, given thorough knowledge of the subsurface environment; (3) the release of uranium from autunite minerals appears to be 6-7 order of magnitude slower than uranium (UO2) minerals formed by iron barrier reduction; and (4) understanding secondary uranyl-phase formation is necessary for predicting the long-term fate of uranium in the environment

  12. Treatability Test Plan for 300 Area Uranium Stabilization through Polyphosphate Injection

    International Nuclear Information System (INIS)

    Vermeul, Vince R.; Williams, M. D.; Fritz, Brad G.; Mackley, Rob D.; Mendoza, Donaldo P.; Newcomer, Darrell R.; Rockhold, Mark L.; Williams, Bruce A.; Wellman, Dawn M.

    2007-01-01

    The U.S. Department of Energy has initiated a study into possible options for stabilizing uranium at the 300 Area using polyphosphate injection. As part of this effort, PNNL will perform bench- and field-scale treatability testing designed to evaluate the efficacy of using polyphosphate injections to reduced uranium concentrations in the groundwater to meet drinking water standards (30 (micro)g/L) in situ. This technology works by forming phosphate minerals (autunite and apatite) in the aquifer that directly sequester the existing aqueous uranium in autunite minerals and precipitates apatite minerals for sorption and long term treatment of uranium migrating into the treatment zone, thus reducing current and future aqueous uranium concentrations. Polyphosphate injection was selected for testing based on technology screening as part of the 300-FF-5 Phase III Feasibility Study for treatment of uranium in the 300-Area

  13. Treatability Test Plan for 300 Area Uranium Stabilization through Polyphosphate Injection

    Energy Technology Data Exchange (ETDEWEB)

    Vermeul, Vincent R.; Williams, Mark D.; Fritz, Brad G.; Mackley, Rob D.; Mendoza, Donaldo P.; Newcomer, Darrell R.; Rockhold, Mark L.; Williams, Bruce A.; Wellman, Dawn M.

    2007-06-01

    The U.S. Department of Energy has initiated a study into possible options for stabilizing uranium at the 300 Area using polyphosphate injection. As part of this effort, PNNL will perform bench- and field-scale treatability testing designed to evaluate the efficacy of using polyphosphate injections to reduced uranium concentrations in the groundwater to meet drinking water standards (30 ug/L) in situ. This technology works by forming phosphate minerals (autunite and apatite) in the aquifer that directly sequester the existing aqueous uranium in autunite minerals and precipitates apatite minerals for sorption and long term treatment of uranium migrating into the treatment zone, thus reducing current and future aqueous uranium concentrations. Polyphosphate injection was selected for testing based on technology screening as part of the 300-FF-5 Phase III Feasibility Study for treatment of uranium in the 300-Area.

  14. Synthesis and crystallochemical analysis of phosphoric analogue of troegerite

    International Nuclear Information System (INIS)

    Sidorenko, G.A.; Zhil'tsova, I.G.; Moroz, I.Kh.

    1975-01-01

    Uranyl phosphate is easily synthesized by adding a 0.36M solution of phosphorous acid of 60degC to a 0.5M solution of uranyle nitrate. The precipitate at pH 0.87-1.10 contains two morphologically different phases - one in the form of quadratic disks (''heavy'' phase) - the other in form of needle-crystals of size up to 0.1 mm (''light'' phase). X-ray analysis determined the ''heavy'' phase as meta-autunite, - the ''light'' phase as uranyl phosphate of composition (UO 2 ):(PO 4 )=3:2. Uranyl phosphate is straw-coloured, its specific weight is 3.45; the luminescence is similar to that of autunite; the refraction index is Nsub(g)=Nsub(m)=1.581; pr=1.570 with a slight pleochroism from light yellow to white; the interference colours are week; the extinction is direct. The chemical analysis of two independently obtained samples of uranyl phosphate was carried out. It led to the crystallo-chemical formula (UO 2 ) 3 (PO 4 ) 2 x 4,8H 2 O. The symmetry and the parameters of the elementary cell of the phosphate are determined: it is a rhombic cell with a=13.11+-0.01A, b=6.98+-0.01A, c=16.91+-0.03A and Z=3. The x-ray density is rho=3.53. The DTA curve shows a higher temperature at the beginning of the dehydration: nearly 120deg compared with the first endoeffect of N-metaautunite which occurs at 50deg. The i.r. spectrum gives a lower symmetry than for N-meta-autunite. The water in the uranyl phosphate is strongly orientated and coupled to the structure. Dumontite which has a ratio (UO 2 ):(PO 4 )=3:2 is found to have a analogous chemical composition to the uranyl phosphate. The parameters b and c are similar in both compounds. The formation of phosphate and the transformation into N-meta-autunite can take place even under natural coditions. The phosphoric analogue of troegerite has the same (UO 2 )/(PO 4 ) ratio but differs in the water content. The structural relations of the two compounds are still unknown

  15. Spectral Induced Polarization Response of Biofilm Formation in Hanford Vadose Zone Sediment

    Science.gov (United States)

    Garcia, A.; Katsenovich, Y.; Lee, B.; Whitman, D.

    2017-12-01

    As a result of the U.S. Nuclear weapons program during the second world war and the cold war, there now exists a significant amount of uranium contamination at the U.S. Department of Energy Hanford site located in Washington state. In-situ immobilization of mobile uranium via injections of a soluble sodium tripolyphosphate amendment may prove effective in the formation of insoluble uranyl phosphate mineral, autunite. However, the injected polyphosphate undergoes hydrolysis in aqueous solutions to form orthophosphate, which serves as a readily available nutrient for the various microorganisms in the sediment. Sediment-filled column experiments conducted under saturated oxygen restricted conditions using geophysical Spectral Induced Polarization technique have shown the impact of microbes on the dissolution of autunite, a calcium uranyl phosphate mineral. Spectral Induced Polarization may be an effective way to track changes indicative of bacterial activities on the surrounding environment. This method can be a cost-effective alternative to the drilling of boreholes at a field scale.

  16. Uranium occurence in California near Bucaramanga (Columbia)

    International Nuclear Information System (INIS)

    Heider Polania, J.

    1980-01-01

    The mining district of California, Bucaramanga, is on the west side of the Cordillera Oriental in the Santander massif region. The oldest rocks of the area form a complex of metamorphites and migmatites of the predevonic age. Amphibolite various types of paragneiss and orthogneiss are represented. Several stages of metamorphism can be documented in some rocks, as well as double anatexis. Triassic to jurassic quarz diorites and leukogranites show wide distribution. Porphyric rocks of granodioritic to granitic composition, to which the uranium mineralization is mainly bonded, intruded into the sediments of the lower cretaceous. Atomic absorption spectral analyses were carried out for the elements Cu, Zn and Li, as well as the uranium contents of some samples using fluorimetry. Uranium is primarily bonded to pitch blende and coffinite. The latter mostly occur in fine distribution grown in quarz and belong to the most recent mineralization phase. Autunite, meta-autunite, torbernite, meta-torbernite, zeunerite, meta-zeunerite and meta uranocircite detected as secondary uranium minerals. (orig./HP) [de

  17. Experimental Plan: 300 Area Treatability Test: In Situ Treatment of the Vadose Zone and Smear Zone Uranium Contamination by Polyphosphate Infiltration

    International Nuclear Information System (INIS)

    Wellman, Dawn M.; Pierce, Eric M.; Oostrom, Mart; Fruchter, Jonathan S.

    2007-01-01

    The overall objectives of the treatability test is to evaluate and optimize polyphosphate remediation technology for infiltration either from ground surface, or some depth of excavation, providing direct stabilization of uranium within the deep vadose and capillary fringe above the 300 Area aquifer. Expected result from this experimental plan is a data package that includes: (1) quantification of the retardation of polyphosphate, (2) the rate of degradation and the retardation of degradation products as a function of water content, (3) an understanding of the mechanism of autunite formation via the reaction of solid phase calcite-bound uranium and aqueous polyphosphate remediation technology, (4) an understanding of the transformation mechanism, identity of secondary phases, and the kinetics of the reaction between uranyl-carbonate and silicate minerals with the polyphosphate remedy under solubility-limiting conditions, (5) quantification of the extent and rate of uranium released and immobilized based on the infiltration rate of the polyphosphate remedy and the effect of and periodic wet-dry cycling on the efficacy of polyphosphate remediation for uranium in the vadose zone and capillary fringe, and (6) quantification of reliable equilibrium solubility values for autunite under hydraulically unsaturated conditions allowing accurate prediction of the long-term stability of autunite. Moreover, results of intermediate scale testing will quantify the transport of polyphosphate and degradation products, and yield degradation rates, at a scale that is bridging the gap between the small-scale UFA studies and the field scale. These results will be used to test and verify a site-specific, variable saturation, reactive transport model and to aid in the design of a pilot-scale field test of this technology. In particular, the infiltration approach and monitoring strategy of the pilot test would be primarily based on results from intermediate-scale testing. Results from this

  18. Mineralogical study of uraniferous graphitic ore from Deogpyeong, Mogso and southern part of Daejeon area

    Energy Technology Data Exchange (ETDEWEB)

    Lee, D J; Nam, S K [Korean Inst. of Energy and Resources, Seoul (Republic of Korea)

    1981-11-01

    Uranium minerals of torbernite, metatorbernite, metatyuyamunite and autunite have been identified from the uraniferous ores in graphitic beds of Ogcheon Group in Deogpyeong, Mogso and southern part of Daejeon area. Polarizing and ore microscopic studies, and chemical and X-ray powder diffraction analyses were carried out on the uraniferous graphite and associated materials. Main component minerals of uraniferous samples are graphite and quartz. Minor minerals are calcite, muscovite, sericite, andalusite, barite, kaolinite, hyaline opal, uranium minerals, sulfides such as pyrite, chalcopyrite, zincblende, and pyrrhotite, limonite, zeolite minerals such as laumontite and heulandite. Metatyuyamunite, torbernite, metatorbernite and autunite generally occur together with secondary minerals such as kaolinite, hyaline opal, calcite and limonite. They were found along the minor fissures or on the surface. Secondary uranium minerals described above were formed by supergenetic origin from primary uranium mineral. Uraniferous phosphatic nodule from Deogpyeong area are mainly composed of graphite and fluorapatite. And minor minerals are barite, quartz, muscovite and pyrite. Autoradiograph from uraniferous nodule shows that uranium enrichment in outer part of nodules is much higher than in inner part. This feature coincides with chemical analyses data of this uraniferous nodule.

  19. Uranium occurrences in the pegmatite 'Las Cuevas', province of San Luis, Argentine Republic

    International Nuclear Information System (INIS)

    Daziano, C.O.; Karlsson, A.C.; Ayala, R.

    1993-01-01

    Mineral associations found in an uranium deposit of Sierras Pampeanas, San Luis, are considered in these papers. Damourite stands out among the uranium minerals related to uraninite and coffinite. Pyrite, marcasite and other sulphides are found together with apatite and gummite. Autunite is the uranium secondary mineral more abundant. A mineralization with epigenetic contribution by circulating solutions is suggested to the studied area. (Author)

  20. Uranium Sequestration by Aluminum Phosphate Minerals in Unsaturated Soils

    International Nuclear Information System (INIS)

    Jerden, James L. Jr.

    2007-01-01

    A mineralogical and geochemical study of soils developed from the unmined Coles Hill uranium deposit (Virginia) was undertaken to determine how phosphorous influences the speciation of uranium in an oxidizing soil/saprolite system typical of the eastern United States. This paper presents mineralogical and geochemical results that identify and quantify the processes by which uranium has been sequestered in these soils. It was found that uranium is not leached from the saturated soil zone (saprolites) overlying the deposit due to the formation of a sparingly soluble uranyl phosphate mineral of the meta-autunite group. The concentration of uranium in the saprolites is approximately 1000 mg uranium per kg of saprolite. It was also found that a significant amount of uranium was retained in the unsaturated soil zone overlying uranium-rich saprolites. The uranium concentration in the unsaturated soils is approximately 200 mg uranium per kg of soil (20 times higher than uranium concentrations in similar soils adjacent to the deposit). Mineralogical evidence indicates that uranium in this zone is sequestered by a barium-strontium-calcium aluminum phosphate mineral of the crandallite group (gorceixite). This mineral is intimately inter-grown with iron and manganese oxides that also contain uranium. The amount of uranium associated with both the aluminum phosphates (as much as 1.4 weight percent) has been measured by electron microprobe micro-analyses and the geochemical conditions under which these minerals formed has been studied using thermodynamic reaction path modeling. The geochemical data and modeling results suggest the meta-autunite group minerals present in the saprolites overlying the deposit are unstable in the unsaturated zone soils overlying the deposit due to a decrease in soil pH (down to a pH of 4.5) at depths less than 5 meters below the surface. Mineralogical observations suggest that, once exposed to the unsaturated environment, the meta-autunite group

  1. Radioactive mineral deposits

    Energy Technology Data Exchange (ETDEWEB)

    1948-01-01

    This publication was designed as a guide for uranium and thorium prospectors in Australia. Physical properties, such as color, streak, luster, hardness, fracture, and specific gravity of the uranium and thorium-bearing minerals are summarized and the various methods suitable for detecting radioactivity in minerals are described. Two colored plates show samples of pitchblende (uraninite), autunite, carnotite, monazite, and others of the most important minerals sources of uranium and thorium.

  2. The geology of uranium mineralization at Mika, N.E. Nigeria

    International Nuclear Information System (INIS)

    Funtua, I.I.; Okujeni, C.P.; Elegba, S.B.

    1995-01-01

    The Uranium mineralization at Mike is located near Zing in Taraba State, N.E., Nigeria. The host rock consist of a sheared Pan-African medium-grained granite which is in places intruded by rhyolite and siliceous veins. Numerous joints, faults and fractures criss-cut the area. Some of the fractures are filled with secondary quartz. The ore occurs in two parallel N-S trending shear Zones with the western limb hosting a rhyolite body. Drill section reveals a subsurface extension of the mineralization. In the upper limb, mineralization consisting of metal autunite and coffinite occurs associated with the rhyolite body. In lower ore limb meta-autunite, coffinite and pitchblende occur along a set of two parallel shear surface. The pitchblende occurs massive and as vein lets in association with sulphides. The ore body is marked by distinct hydrothermal alteration zones which feature sericitization, silicification, hematization and kaolination. Reactivated regional structures of NE-SW and the N140oE and N170E played an important role in the formation of Mika mineralization. These acted as channel and as mechanical barrier for the mineralization fluid. The bimodal magmatism of the Burashika group is postulated to be related to the process of mineralization in view of the ubiquitous rhyolite in the mineralized bodies

  3. Processing of Madagascar's concentrates; Traitement des concentres de Madagascar

    Energy Technology Data Exchange (ETDEWEB)

    Mouret, P; Madinier, A

    1949-06-01

    This report describes the equipment (tanks, filters..) of the ore processing workshop of Le Bouchet used for the processing of the uranium ore from Madagascar (autunite). Then it describes the processing scheme: treatment with sodium carbonate, de-complexing of uranyl carbonate with soda, filtering, washing, drying and calcination of sodium uranate. The volume of reagents used, the production rate and the purity of the uranate obtained are given in conclusion. (J.S.)

  4. Distribution of uranium-bearing phases in soils from Fernald

    International Nuclear Information System (INIS)

    Buck, E.C.; Brown, N.R.; Dietz, N.L.

    1993-01-01

    Electron beam techniques have been used to characterize uranium-contaminated soils and the Fernald Site, Ohio. Uranium particulates have been deposited on the soil through chemical spills and from the operation of an incinerator plant on the site. The major uranium phases have been identified by electron microscopy as uraninite, autunite, and uranium phosphite [U(PO 3 ) 4 ]. Some of the uranium has undergone weathering resulting in the redistribution of uranium within the soil

  5. The fergusonite from Ampasipoana (Madagascar). Alteration mode and uranium transport

    International Nuclear Information System (INIS)

    Chervet, J.

    1958-01-01

    The author reports, comments and discusses the general characteristics of the fergusonite, a primary ore of uranium, and more particularly those of a very specific ore extracted from a large deposit located in Madagascar. These characteristics notably concern the composition and the presence and shapes of various crystals. The studied ore contains yttrium phosphate which demonstrated an attack of uranium and yttrium niobate by phosphated acid solutions, and the formation of autunite provided by the fergusonite uranium

  6. Mineralogical Study of Workable Material Coming from Mina Fe Ciudad Rodrigo

    International Nuclear Information System (INIS)

    Mingarro Martin, E.

    1962-01-01

    A mineralogical analysis is made to ascertain the effects of acid bleaching on normalized conditions. Uranium is mainly found under uranotile, pitchblende and autunite form with an average assay of 0.4 p. ct. The loss of uranium in tailings under current conditions of attach, mainly is due to pitchblende resistance, being practically no leachable, and to uranium absorption by hydrated iron oxides and colloidal ores. This last problem will be discussed in a next paper. (Author) 5 refs

  7. Mineralogical Study of Workable Material Coming from Mina Fe Ciudad Rodrigo; Estudio mineralogico del material beneficiable procedente de la Mina Fe. Ciudad Rodrigo (Salamanca)

    Energy Technology Data Exchange (ETDEWEB)

    Mingarro Martin, E

    1962-07-01

    A mineralogical analysis is made to ascertain the effects of acid bleaching on normalized conditions. Uranium is mainly found under uranotile, pitchblende and autunite form with an average assay of 0.4 p. ct. The loss of uranium in tailings under current conditions of attach, mainly is due to pitchblende resistance, being practically no leachable, and to uranium absorption by hydrated iron oxides and colloidal ores. This last problem will be discussed in a next paper. (Author) 5 refs.

  8. Uranium-contaminated soils: Ultramicrotomy and electron beam analysis

    International Nuclear Information System (INIS)

    Buck, E.C.; Dietz, N.L.; Bates, J.K.; Cunnane, J.C.

    1994-01-01

    Uranium contaminated soils from the Fernald Operation Site, Ohio, have been examined by a combination of optical microscopy, scanning electron microscopy with backscattered electron detection (SEM/BSE), and analytical electron microscopy (AEM). A method is described for preparing of transmission electron microscopy (TEM) thin sections by ultramicrotomy. By using these thin sections, SEM and TEM images can be compared directly. Uranium was found in iron oxides, silicates (soddyite), phosphates (autunites), and fluorite. Little uranium was associated with clays. The distribution of uranium phases was found to be inhomogeneous at the microscopic level

  9. Petrology, mineralogy and geochemistry of surficial uranium deposits

    International Nuclear Information System (INIS)

    Pagel, M.

    1984-01-01

    A comprehensive understanding of the petrology, mineralogy, and geochemistry of surficial uranium ore deposits is important for developing prospecting and evaluation strategies. Carnotite is the main uranium mineral and is found in those deposits that have the greatest potential uranium resources. The following uranium-bearing minerals have been reported to occur in surficial deposits: carnotite, tyuyamunite, soddyite, weeksite, haiweeite, uranophane, betauranophane, metaankoleite, torbernite, autunite, phosphuranylite, schroeckingerite, Pb-V-U hydroxide (unnamed mineral), uraninite and organourano complexes. The interrelationships between some of the minerals of the host rocks (especially the clays) are not well understood. (author)

  10. Factor analysis of geochemical data from ore and host rocks of the uranium mineralization at Mika, N. E. Nigeria

    International Nuclear Information System (INIS)

    Funtua, I. I.

    1997-01-01

    The Mika uranium occurrence is located in one of a series of NW-NE trending shear zones which host uraniferous Jurassic rhyolitic dykes located in Pan-African brecciated granites within peraluminous granite complex of NE Nigeria. The bodies of mineralization are about 100 metres long and up to 4 metres thick. The U mineralization associated with the rhyolite dykes contains predominantly meta-autunite and apatite, while that of the brecciated granites displays variable mineralogy with meta-autunite, one or two generations of coffinite and colloformic, pitch blend in open veins. The mineralization is thought to be related to bimodel magmatism of the Burashika group and the reactivation of regional structures. Multivariate statistical evaluation of geochemical data of 28 elements/oxides in 296 host rock and mineralized samples from the surface and drill cores display a coherent association of [(U, Pb, Zn, Cu, P 2 O 5 , Fe 2 O 3 ) + Mo], [(CaO, Zr, Sr) +(Y, Mo, V, As)] and [(MgO, K 2 O) + (TiO 2 , Rb)] in the mineralized rocks; reflecting the presence of hamatized phosphate bearing ores in association with sulphide minerals and apatite in the granite rhyolites. A link of the mineralizing fluids with the emplacement of the rhyolites is implied from the striking resemblance between the above element association in mineralized rocks to those of the unmineralized rhyolites. A source of ore fluids over saturated in uranium and silica emanating from crystallizing rhyolitic melts which were expelled into faults and/or shear zones in the surrounding country rock is inferred

  11. Radiometric geological exploration method used in the central part of the State of Sonora

    International Nuclear Information System (INIS)

    Pacheco R, R.

    1978-01-01

    The purpose of this study is to make known the importance of the radiometric data, the physical principles on which they are based and the geological interpretation which will permit in an indirect way to select important radioactive areas in order to carry out verification studies on the ground to see if there are sufficient reasons to show any interest in these areas. Till now this work has been realized in the State of Sonora (Mexico) in an area of 51,000 Km 2 subdivided in 14 zones, numbered from 201 to 214, and for the present work the zone 208 has been selected. This Zone is located at the north-west of the City of Hermosillo, and has a total area of 3400 Km 2 which has been the object of the study by plane through systematic flights in an east-west direction, in order to obtain the configuration and interpret it from a radiometrical point of view. The obtained isorads configuration plans of 4 channels of detection are the following: total counting, potassium, bismuth and thallium as well as their relations. From the 14 verified anomalies the anomaly Noche Buena was selected in order to carry out reconnaissance surveys and preliminary and detailed geological studies. The geology of the area is represented by extrusive and intrusive igneous rocks as well as sedimentary. The uraniferous mineralization is secondary and is represented by autunite, meta-autunite and torbenite which represent an average of 200 g to 3.08 Kg. of U 3 O 8 per ton. (author)

  12. Use of combined microscopic and spectroscopic techniques to reveal interactions between uranium and Microbacterium sp. A9, a strain isolated from the Chernobyl exclusion zone

    Energy Technology Data Exchange (ETDEWEB)

    Theodorakopoulos, Nicolas [CEA, DSV, IBEB, SBVME, LIPM, F-13108 Saint-Paul-lez-Durance (France); CNRS, UMR 7265, F-13108 Saint-Paul-lez-Durance (France); Université d' Aix-Marseille, F-13108 Saint-Paul-lez-Durance (France); IRSN/PRP-ENV/SERIS/L2BT, bat 183, B.P. 3, F-13115 Saint Paul-lez-Durance (France); Chapon, Virginie [CEA, DSV, IBEB, SBVME, LIPM, F-13108 Saint-Paul-lez-Durance (France); CNRS, UMR 7265, F-13108 Saint-Paul-lez-Durance (France); Université d' Aix-Marseille, F-13108 Saint-Paul-lez-Durance (France); Coppin, Fréderic; Floriani, Magali [IRSN/PRP-ENV/SERIS/L2BT, bat 183, B.P. 3, F-13115 Saint Paul-lez-Durance (France); Vercouter, Thomas [CEA, DEN, DANS, DPC SEARS, LANIE, F-91191 Gif-Sur-Yvette Cedex (France); Sergeant, Claire [Univ Bordeaux, CENBG, UMR5797, F-33170 Gradignan (France); CNRS, IN2P3, CENBG, UMR5797, F-33170 Gradignan (France); Camilleri, Virginie [IRSN/PRP-ENV/SERIS/L2BT, bat 183, B.P. 3, F-13115 Saint Paul-lez-Durance (France); Berthomieu, Catherine [CEA, DSV, IBEB, SBVME, LIPM, F-13108 Saint-Paul-lez-Durance (France); CNRS, UMR 7265, F-13108 Saint-Paul-lez-Durance (France); Université d' Aix-Marseille, F-13108 Saint-Paul-lez-Durance (France); Février, Laureline, E-mail: laureline.fevrier@irsn.fr [IRSN/PRP-ENV/SERIS/L2BT, bat 183, B.P. 3, F-13115 Saint Paul-lez-Durance (France)

    2015-03-21

    Highlights: • Microbacterium sp. A9 develops various detoxification mechanisms. • Microbacterium sp. A9 promotes metal efflux from the cells. • Microbacterium sp. A9 releases phosphate to prevent uranium entrance in the cells. • Microbacterium sp. A9 stores U intracellularly as autunite. - Abstract: Although uranium (U) is naturally found in the environment, soil remediation programs will become increasingly important in light of certain human activities. This work aimed to identify U(VI) detoxification mechanisms employed by a bacteria strain isolated from a Chernobyl soil sample, and to distinguish its active from passive mechanisms of interaction. The ability of the Microbacterium sp. A9 strain to remove U(VI) from aqueous solutions at 4 °C and 25 °C was evaluated, as well as its survival capacity upon U(VI) exposure. The subcellular localisation of U was determined by TEM/EDX microscopy, while functional groups involved in the interaction with U were further evaluated by FTIR; finally, the speciation of U was analysed by TRLFS. We have revealed, for the first time, an active mechanism promoting metal efflux from the cells, during the early steps following U(VI) exposure at 25 °C. The Microbacterium sp. A9 strain also stores U intracellularly, as needle-like structures that have been identified as an autunite group mineral. Taken together, our results demonstrate that this strain exhibits a high U(VI) tolerance based on multiple detoxification mechanisms. These findings support the potential role of the genus Microbacterium in the remediation of aqueous environments contaminated with U(VI) under aerobic conditions.

  13. Phurcalite and others secondary uranium minerals from Perus, Sao Paulo, Brazil

    International Nuclear Information System (INIS)

    Atencio, D.

    1991-01-01

    Phurcalite has been found filling fractures in the tourmaline-bearing granitic pegmatite of Perus, in the north-west part of Sao Paulo city, Brazil. It forms aggregates of radiating euhedral crystals up to 5 mm in length. The crystals are bright yellow, transparent and display vitreous to adamantine lustre. Its streak is pale yellow. Phurcalite is brittle, with a conchoidal fracture, and non-fluorescent. The crystal structure of phurcalite has been solves by single-crystal x-ray diffraction methods and refined to R = 3.8% using 2065 observed [I > 3σ(I)] reflections. The structure consists of [(U O 2 ) 3 O 2 (P O 4 ) 2 4n- ] n layers, parallel to (010), connected by Ca 2+ ions and H 2 O. The coordination polyhedra are: for U(1) hexagonal bi pyramid; for U(2) and U(3) pentagonal bi pyramids; for Ca(4) and Ca(5) capped trigonal prism and triangulated dodecahedron, respectively; and for P(6) and P(7) tetrahedra. As a consequence of this work, the molecular formula of phurcalite previously reported as Ca 2 (U O 2 ) 3 (P O 4 ) 2 (OH) 4 .4 H 2 O must be changed to Ca 2 (U O 2 ) 3 O 2 (P O 4 ) 2 .7 H 2 O. Other secondary uranium minerals associated with Perus phurcalite are autunite, torbernite, meta-autunite, meta-torbernite, chernikovite, meta-uranocircite I, phosphuranylite, uranophane-alpha, uranophane-beta, haiweeite, barian week site and perhaps also bassetite, meta-tyuyamunite and meta-haiweeite. Opal, tridymite, cristobalite, secondary quartz, saponite and rhodochrosite occur associated to the uranium minerals. (author)

  14. Uranium-contaminated soils: Ultramicrotomy and electron beam analysis

    International Nuclear Information System (INIS)

    Buck, E.C.; Dietz, N.L.; Bates, J.K.; Cunnane, J.C.

    1994-02-01

    Uranium-contaminated soils from the U.S. Department of Energy (DOE) Fernald Site, Ohio, have been examined by a combination of scanning electron microscopy with backscattered electron imaging (SEM/BSE) and analytical electron microscopy (AEM). The inhomogeneous distribution of particulate uranium phases in the soil required the development of a method for using ultramicrotomy to prepare transmission electron microscopy (TEM) thin sections of the SEM mounts. A water-miscible resin was selected that allowed comparison between SEM and TEM images, permitting representative sampling of the soil. Uranium was found in iron oxides, silicates (soddyite), phosphates (autunites), and fluorite (UO 2 ). No uranium was detected in association with phyllosilicates in the soil

  15. Uranium concentrations in the phosphates of Congo related to marin and continental mineral authigenesis

    International Nuclear Information System (INIS)

    Giresse, P.; N'Landou, J. de Dieu; Wiber, M.

    1984-01-01

    In the Maastrichtian phosphates of Tchivoula (Congo), uanium, for the most part fixed and tetravalent in marine apatites in there after mobilized and occasionally concentrates during the course of successive stages of dissolution, recrystallization (secondary apatite) or authigenesis (ferro-aluminous phosphates, autunite and torbernite). Very high levels near the top of the deposit appear to be related to the percolation of uraniferous solutions from Ypresian phosphatic beds which are no longer present. In the marine Tertiary phosphates of Djeno, diagenesis is less advanced; radial changes in uranium concentration on the scale of individual coprolites of selacians can be observed and are related to the loss of P 2 O 5 [fr

  16. Phurcalite and others secondary uranium minerals from Perus, Sao Paulo, Brazil; Furcalita e outros minerais uraniferos secundarios de Perus, Sao Paulo

    Energy Technology Data Exchange (ETDEWEB)

    Atencio, D

    1992-12-31

    Phurcalite has been found filling fractures in the tourmaline-bearing granitic pegmatite of Perus, in the north-west part of Sao Paulo city, Brazil. It forms aggregates of radiating euhedral crystals up to 5 mm in length. The crystals are bright yellow, transparent and display vitreous to adamantine lustre. Its streak is pale yellow. Phurcalite is brittle, with a conchoidal fracture, and non-fluorescent. The crystal structure of phurcalite has been solves by single-crystal x-ray diffraction methods and refined to R = 3.8% using 2065 observed [I > 3{sigma}(I)] reflections. The structure consists of [(U O{sub 2}){sub 3} O{sub 2} (P O{sub 4}){sub 2} {sup 4n-}]{sub n} layers, parallel to (010), connected by Ca{sup 2+} ions and H{sub 2} O. The coordination polyhedra are: for U(1) hexagonal bi pyramid; for U(2) and U(3) pentagonal bi pyramids; for Ca(4) and Ca(5) capped trigonal prism and triangulated dodecahedron, respectively; and for P(6) and P(7) tetrahedra. As a consequence of this work, the molecular formula of phurcalite previously reported as Ca{sub 2} (U O{sub 2}){sub 3} (P O{sub 4}){sub 2} (OH){sub 4}.4 H{sub 2} O must be changed to Ca{sub 2} (U O{sub 2}){sub 3} O{sub 2} (P O{sub 4}){sub 2}.7 H{sub 2} O. Other secondary uranium minerals associated with Perus phurcalite are autunite, torbernite, meta-autunite, meta-torbernite, chernikovite, meta-uranocircite I, phosphuranylite, uranophane-alpha, uranophane-beta, haiweeite, barian week site and perhaps also bassetite, meta-tyuyamunite and meta-haiweeite. Opal, tridymite, cristobalite, secondary quartz, saponite and rhodochrosite occur associated to the uranium minerals. (author).

  17. Mineralización de uranio en la Sierra de Velasco, La Rioja

    International Nuclear Information System (INIS)

    Morello, O.; Aparicio González, P.

    2013-01-01

    This contribution describes an uranium mineralization found in the Sierra de Velasco, La Rioja Province, Northwest of Ar¬gentina. In the study area crop out granites, pegmatites and metamorphic rocks. The host rocks of the mineralization are the La Chinchilla Granite (Carboniferous) and the La Cébila metamorphic Complex (Precambrian-Ordovician). The mine¬ralization is perigranitic and occurs disseminated, in fractures and in the contact between the granite and the metamorphic rocks. In the La Chinchilla Granite was identified a U-Nb-Ta oxide, and in the metamorphic rocks U-silicates (uranophane, uranophane-beta), U-phosphates (phurcalite and meta-autunite) and uranium oxides (pitchblende and coffinite) were found. (authors) [es

  18. Sedimentary uranium deposit of the Ipora/Amorinopolis region, state of Goias, Brazil

    International Nuclear Information System (INIS)

    Fernandes, S.M.; Leonardos, O.H.

    1984-01-01

    The uranium mineralization is chiefly found within arkosic sandstones at the base of the Devonian Ponta Grossa Formation. The ore is tabular and concordant with the bedding, the controls being simultaneously litho-stratigraphical and biochemical. Narrow permeable horizons of arkosic sandstone lie between impermeable shale and siltstone layers. Within the permeable horizon, the fossil remains (probably brachiopods) are replaced by uranium minerals. The oxidized iron minerals may have acted as to insulate and preserve the secondary soluble uranium minerals. The mineral paragenesis is represented by renardite, meta - autunite I, fourmarierite, Koninckite, ranquilite, meta-uranocircite II, barite, apatite, calophane, wavelite, varscite, an unnamed uranium mineral, quartz, calcedony, goethite, lepidocrocite and hematite. (Author) [pt

  19. Uranium mineralization in the Mesoproterozoic Banganapalle formation near Nagayapalle, Cuddapah Basin, Andhra Pradesh

    International Nuclear Information System (INIS)

    Basu, Himadri; Harikrishnan, T.; Hanumanthappa, D.; Rengarajan, M.; Saravanan, B.; Bhagat, Sangeeta; Mahendra Kumar

    2008-01-01

    Cuddapah Basin is the hub of uranium exploration for years together in India. Initial efforts were for quartz-pebble-conglomerate type mineralization. However, the emphasis later shifted towards dolostone-hosted mineralization and finally to unconformity-associated uranium mineralization. The recent finding of uranium mineralization associated with the Banganapalle Formation near Nagayapalle is the outcome of continuous exploration input in the Cuddapah Basin over years. Uranium mineralization (up to 0.278% U 3 O 8 ) associated with the Mesoproterozoic Banganapalle Formation near Nagayapalle is represented by pitchblende and autunite. Pitchblende occurs as tiny grains in the intergranular spaces and along grain boundaries; and also at places replaces pyrite and covellite grains. The geological set-up indicates that the geodomain is favourable for uranium mineralization. (author)

  20. Dating methods based on the radioactive disequilibrium (1961); Methodes de chronologie par le desequilibre radioactif (1961)

    Energy Technology Data Exchange (ETDEWEB)

    Coquema, C; Coulomb, R; Goldsztein, M; Schiltz, J C [Commissariat a l' Energie Atomique, Fontenay-aux-Roses (France). Centre d' Etudes Nucleaires

    1961-07-01

    The existence in the uranium families of two long-life descendants: ionium (half-life 80000 years) and protactinium (half-life 32000 years), together with the differences in geochemical behaviour of the various natural radio-elements, particularly thorium, make it possible to envisage several models of geological time-scales covering-periods from 0 to 500000 years The theory of two of the most important models i s developed and methods are described for making radiochemical measurements on the various nuclides which are essential for resolving these models (U{sup 238}, Th{sup 234}, Th{sup 230}, Ra{sup 226}, Pa{sup 231}, Th{sup 232}, Th{sup 228}, Po{sup 210}) An example of dating is given in the case of a secondary mineralisation on a weathered portion of a deposit in the Limouzat (Forez). Samples of autunite and chalcolite taken at different levels of the mine were calculated to be between 30000 and 240000 years old. (authors) [French] L'existence dans les familles de l'uranium de deux descendants a vie longue: ionium (periode 80000 ans) et protactinium (periode 32000 ans), ainsi que les differences tie comportement geochimique des divers radioelements naturels, en particulier du thorium, permettent d'envisager plusieurs modeles d'echelles geochronologiques couvrant un domaine allant de 0 a 500000 ans. Nous developpons la theorie de deux de ces modeles les plus importants, et decrivons les methodes de dosage radiochimiques des divers nucleides dont la connaissance est necessaire a la resolution des modeles ({sup 238}U, {sup 234}Th, {sup 230}Th, {sup 226}Ra, {sup 231}Pa, {sup 232}Th, {sup 228}Th, {sup 210}Po). On donne un exemple de chronologie d'une mineralisation secondaire sur la partie alteree du gisement du Liznouzat (Forez). Des echantillons d'autunite et de chalcolite pris a differents niveaux de la mine ont pu etre dates de 30000 a 240000 ans. (auteurs)

  1. Technological studies on the Manisa-Koprubasi uranium ores of Turkey

    International Nuclear Information System (INIS)

    Sagdik, U.

    1980-01-01

    At the end of the laboratory and pilot plant scale technological experiments, three main types of ore have been classified: (i) Kasar type: The ores consist of secondary uranium mineralization (autunite, meta-autunite and torbenite) in loosely consolidated sands, gravels and clays of Neogene Age. Heap leaching has been carried out on 100 and 1000 t ore samples (0.05% U 3 O 8 ) under economical conditions, such as 20 to 40 kg of H 2 SO 4 per tonne of ore at ambient temperature; original size -20 cm, solid/liquid ratio of 10, 20 days, and 90% recovery of uranium has been reached. The uraniferous solutions (1 to 2 g of U 3 O 8 per litre) obtained from the heap leaching operations were purified in a solvent extraction unit with a capacity of 100 ltr/h by using an Alamine 336-kerosene-decanol solution. The uranium in the purified and concentrated solutions (15 g of U 3 O 8 per litre) was then precipitated as a yellow cake with 65 to 75% U 3 O 8 content by means of magnesia milk. (ii) Tasharman type: No specific uranium mineral has been detected in the mineralogical determination, although uranium is disseminated in phosphate minerals as dahllite and apatite. Uranium in the ore has been leached under rather uneconomical conditions; 100 kg of H 2 SO 4 per tonne of ore, particle size -1 cm, 25 0 C, 30 days. In the SX-treatment of pregnant solutions phosphate ions, higher acidity than pH 1, and compounds formed as a chemical precipitation, hindered the SX-recoveries. In such cases, the addition of acid, dilution of pregnant solutions, membrane filtration, or 40 0 C temperature have been applied to decrease the uranium loss in the raffinate. (iii) Carbonate type: Even if alkaline leaching at 65 0 C, or leaching with 400 kg of H 2 SO 4 per tonne of ore, was carried out on -200 mesh ore samples, no acceptable uranium recoveries were obtained

  2. Surficial uranium deposits in Algeria

    International Nuclear Information System (INIS)

    Mokaddem, M.; Fuchs, Y.

    1984-01-01

    Along southern border of the Hoggar (Algeria) Precambrian shield, Lower Palaeozoic sediments lie unconformably on weathered metamorphic rocks. Along the eastern border of the Tin Seririne basin some good examples of the weathered rocks underneath the unconformity are exposed. The palaeosurface is a peneplain with only minor topographical reliefs from one to a few metres high. The nature and intensity of the weathering process was controlled by the topography, and the existence of badly drained areas is particularly important. At one such area the Tahaggart uranium ore deposit was discovered. The uranium ore consists mainly of torbernite and autunite. The deposit is present in the weathered gneiss underneath the palaeosurface. Mineralogical and geochemical observations indicated that the ore deposit was formed during the period of weathering which was controlled by climatological and palaeotopographical factors. (author)

  3. Minerals from Morvan; Les mineraux du Morvan

    Energy Technology Data Exchange (ETDEWEB)

    Bayle, L.D

    2007-07-01

    Morvan is a mountainous and wooded region of Bourgogne (Burgundy, France) which represents the NE end of the French Massif central. The geologic history of this area has been propitious to the setting up of numerous ore deposits: iron, fluor, manganese, lead, barium and uranium. Morvan is the cradle of the French uranium industry. This book presents, first, the geology, geodynamics and ore deposits of Morvan, the history of the discovery of autunite and the exploitation of uranium. The three uranium mining districts are reviewed with the list of uranium minerals. The uranium exploitation activity was abandoned in 1990. An overview of a dozen of fluorine, barytine, lead and silver-bearing ore deposits is presented as well. A summary of all other mineral species associated to the granitic, metamorphic and volcanic areas of the region is proposed. (J.S.)

  4. Uranium potential inventory on systematic prospection stage at Jumbang I sector, West Kalimantan

    International Nuclear Information System (INIS)

    Widodo, Manto; Rusmadi; Widito, P.; Marzuki, Anang; Sularto, Priyo

    2002-01-01

    At Jumbang I sector, West Kalimantan was discovered a uranium mineralization as outcrops, boulders, and high radioactivity soils. This research aim is to get know how of the extension, characters, and potential. The research approach was topographic, geologic, and radiometric soil mapping, trenching, and mineralogical and chemical analysis. The results are soil radiometric anomalies orientation are WNW-ESE strike or N-S, appropriate to the mineralization orientation. The mineralization have filled WNW-ESE fractures and associated with N-S fractures and it can be distinguished into five mineralization zones. The radioactive mineral consists of uraninite, gummite, autunite, and monazite, which are associated with magnetite, ilmenite, pyrite, quartz, feldspar, pyrrhotite, and chalcopyrite. Geochemically, the uranium content is well correlated with Co (R=0.601), Ni (R=0.646), Ag (R=0.752), Au (R=0.654), Pb (R=0.896) and Mo (R=0.847). The mineralization at Jumbang I sector could be classified as vein type granite related subtype, peri granitic class. Their potential until 50 m depth is 230.08 tons U within the speculative category of resources

  5. Biomineralization of Uranium by PhoY Phosphatase Activity Aids Cell Survival in Caulobacter crescentus

    Energy Technology Data Exchange (ETDEWEB)

    Yung, M C [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Jiao, Y [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2014-07-22

    Caulobacter crescentus is known to tolerate high levels of uranium [U(VI)], but its detoxification mechanism is poorly understood. Here we show that C. crescentus is able to facilitate U(VI) biomineralization through the formation of U-Pi precipitates via its native alkaline phosphatase activity. The U-Pi precipitates, deposited on the cell surface in the form of meta-autunite structures, have a lower U/Pi ratio than do chemically produced precipitates. The enzyme that is responsible for the phosphatase activity and thus the biomineralization process is identified as PhoY, a periplasmic alkaline phosphatase with broad substrate specificity. Furthermore, PhoY is shown to confer a survival advantage on C. crescentus toward U(VI) under both growth and nongrowth conditions. Results obtained in this study thus highlight U(VI) biomineralization as a resistance mechanism in microbes, which not only improves our understanding of bacterium-mineral interactions but also aids in defining potential ecological niches for metal-resistant bacteria.

  6. Immobilization of uranium in biofilm microorganisms exposed to groundwater seeps over granitic rock tunnel walls in Olkiluoto, Finland

    Science.gov (United States)

    Krawczyk-Bärsch, Evelyn; Lünsdorf, Heinrich; Pedersen, Karsten; Arnold, Thuro; Bok, Frank; Steudtner, Robin; Lehtinen, Anne; Brendler, Vinzenz

    2012-11-01

    In an underground rock characterization facility, the ONKALO tunnel in Finland, massive 5-10-mm thick biofilms were observed attached to tunnel walls where groundwater was seeping from bedrock fractures at a depth of 70 m. In laboratory experiments performed in a flow cell with detached biofilms to study the effect of uranium on the biofilm, uranium was added to the circulating groundwater (CGW) obtained from the fracture feeding the biofilm. The final uranium concentration in the CGW was adjusted to 4.25 × 10-5 M, in the range expected from a leaking spent nuclear fuel (SNF) canister in a future underground repository. The effects were investigated using microelectrodes to measure pH and Eh, time-resolved laser fluorescence spectroscopy (TRLFS), energy-filtered transmission electron microscopy (EF-TEM), and electron energy-loss spectroscopy (EELS) studies and thermodynamic calculations were utilized as well. The results indicated that the studied biofilms constituted their own microenvironments, which differed significantly from that of the CGW. A pH of 5.37 was recorded inside the biofilm, approximately 3.5 units lower than the pH observed in the CGW, due to sulfide oxidation to sulfuric acid in the biofilm. Similarly, the Eh of +73 mV inside the biofilm was approximately 420 mV lower than the Eh measured in the CGW. Adding uranium increased the pH in the biofilm to 7.27 and reduced the Eh to -164 mV. The changes of Eh and pH influenced the bioavailability of uranium, since microbial metabolic processes are sensitive to metals and their speciation. EF-TEM investigations indicated that uranium in the biofilm was immobilized intracellularly in microorganisms by the formation of metabolically mediated uranyl phosphate, similar to needle-shaped autunite (Ca[UO2]2[PO4]2·2-6H2O) or meta-autunite (Ca[UO2]2[PO4]2·10-12H2O). In contrast, TRLFS studies of the contaminated CGW identified aqueous uranium carbonate species, likely (Ca2UO2[CO3]3), formed due to the high

  7. The natural radioactivity in the Serido Pegmatite Province - Rio Grande do Norte State (Brazil): assessment and monitoring of water's source

    International Nuclear Information System (INIS)

    Campos, Thomas F.C; Petta, Reinaldo A.; Malanca, Alberto; Guimaraes Guedes, Anderson; Pastura, Valeria F.S.; Sindern, Sven

    2008-01-01

    Full text: This abstract show the preliminary considerations of a study accomplished on the radioactive minerals, primary and secondary uranium minerals that occur in the pegmatites of the Serido Region, State of Rio Grande do Norte, Brazil and their influence on the several sources of water provision and on population nuclei of the area from the municipal district of Parelhas and Ecuador. In general, the pegmatite from the area of Ecuador-Parelhas present high environmental radioactivity so much due to the dispersed uranium in the crystalline structure of minerals (columbite-tantalite, albite, microcline, quartz, phosphate minerals, tourmaline, lepidolite and apatite), as primary and secondary uranium minerals (uraninite, pitchblende, gummite, autunite, torbernite, and uranium-bearing opal, etc.). These uranium minerals appear associates to the fracture and voids in the pegmatite and in the tourmaline-bearing granite. These minerals were identified by petrography, X-Rays diffraction, ultraviolet fluorescence analysis, infrared spectroscopy, radioactivity (HPGe gamma spectrometry), thermal behavior and chemical analysis (ICP-MS and AAS, Microprobe). Geochemistry and hydrochemistry preliminary environmental studies on the pegmatites bodies from Serido Region show gamma radiation level which between 150 to 30.000 cps; uranium (U 3 O 8 ) and thorium (ThO 2 ) content in Columbite-Tantalite (and/or polycrase) varying between 0,3% - 3,0% and 0,1% - 0,5% respectively, and the coating existent in these minerals show uranium contents varying between 20% to 60%. While the soil samples gathered in Ecuador/Parelhas districts show an average activity of 226 Ra, 232 Th, and 40 K of 27.1/39.1; 33.74/48.5; 260.1/234.8 (Bq.kg -1 , dry-weight), respectively, and the corresponding kerma rate (l) in air are 50 and 67 nGyh -1 ], suggesting that the acid underground waters and others oxidizers attack and dissolve the radioactive minerals from pegmatite, generating solutions rich in U 6

  8. The Geology And Geochemistry Of Zona Uranium Occurence, Upper Benue Trough; N.E. Nigeria

    International Nuclear Information System (INIS)

    Ogunleye, P.O.; Okujeni, C.D.

    1993-01-01

    The Zona uranium is located at the NE flank of the Peta syncline, which is an arm of the Middle Gongola Basin. The hostreok- the Cretaceous Bima sandstone bears the imprint of more than two preore tectonic episodes which are thought to have resulted from reactivation of paleolineaments in the basement since the Pan African Orogeny. The mineralized zone occurs at point of intersection of a set of NE-SW trending shear zone and N-S fracture system. The centre of the ore zone exhibits intense alteration features such as sericitization, ferruginization, silification, remobilization and powdering of the rock matrix. These alteration features diminish progressively from the core to the periphery of the ore zone. The main uraniferous minerals identified are phosphouranylite and meta-autunite. These occur mainly absorbed to iron oxides, in silicified veinlets and partly disseminated in the matrix of the sandstone. Evaluation of the analytical data of 9 elements in 67 rock samples suggest a close link between ferruginization and enrichment of uranium. A model involving the leaching of the uranium from conceal volcanics (rhyolites) and granites at depths by heated groundwater residual magmatic solutions is proposed

  9. Uranium occurrence at Serra dos Quintos, Parelhas, Rio Grande do Norte, Brazil

    International Nuclear Information System (INIS)

    Favali, J.C.; Pires, A.C.R.

    1974-01-01

    The uraniferous showing of Serra dos Quintos near Parelhas, RN, was one of the first discoveries in the Serido belt and it was very interesting because of its uraninite-bearing sheared structure and polymetallic assemblage. The proposed model is the vein-type, the mineralization occurring is lens-like bodies with uranium remobilized from ancient sediments by later Precambrian faulting. The area is made up by migmatites and ectinites of the Caico Complex, Lower Precambrian and quartzites and conglomerates belonging to the Serido Complex, Upper Precambriam. Pegmatites cross-cut the units as concordant and discordant bodies. Structurally the prospect lies on the east flank of the Serra dos Quintos anticline, a north-northeasternly striking structure. The following uranium minerals are known at the locality: uranite, pitchblende (rare), kasolite, autunite and uranophane. Among the metallic minerals, magnetite, pyrite, pirrotite, chalcopyrite and galena are identified. The gangue is composed of quartz, calcite, chlorite and epidote. The drilling program has indicated a mineralized zone 400 meters long, tested to 60 bellow surface with an average of 0,2% U 3 O 8 over 0,90 m in thickness [pt

  10. Uranium resources inventory on systematic prospection stage at Jumbang II Sector West Kalimantan

    International Nuclear Information System (INIS)

    Subiantoro, Lilik; Paimin; Suripto; Widito, P.; Marzuki, Anang

    2002-01-01

    Some uranium occurrences have been discovered as mineralized outcrops and soils at Jumbang II sector. The aim of this investigation is to find the mineralization characteristic, geometric and distribution and resources estimation. The investigation method is systematic topographic, geologic, and radiometric mapping and identification of uranium on the geological aspect. At Jumbang II have been identified four mineralization zones within total area 8.56 hectare. The mineralization zones consist of quartzite rock associations. The quartzite is characterized by the existence of some mineralized veins. The veins contain uraninite and secondary uranium mineral autunite and gummite, and it also contains monazite, tourmaline, biotite, feldspar, quartz, zircon, and some ore minerals. The ore minerals consist of molybdenite, pyrrhotite, magnetite, pyrite, hematite, chalcopyrite, galena, sphalerite and arsenopyrite. Uranium content of quartzite is about 28 ppm to 18,500 ppm U (A zone), 1,125.9 ppm U (B zone) and 515 ppm U (C and D zone). The lateral and vertical ore distributions are locally. The mineralization is veins type and is controlled by intersection WNW-ESE, NNE-EEW structure direction, which was vertical to sub vertical fractures. Resources potential within 80-m depth is 3,106.893 tons U metal

  11. Report on the geological-geochemical research carried out within the area of geochemical anomaly P7, Vathyrema, Drama Department

    International Nuclear Information System (INIS)

    Stavropoulos, Athanasios.

    1982-08-01

    The investigated area covering about 30 km 2 is situated in the crystalline massive of Rhodope (north of Drama deparment, E. Macedonia) where granitoids constitute its main petrological type. The geological-geochemical and radiometric investigations carried out so far in the area have localized a large number of places with high values of γ-radiation (1.000 - 15.000 c/s), as well as high concentrations of uranium (50-500 ppm). The uranium mineralization within the zone of oxidation is expressed by the uranium mineral autunite, accompanied by intensive hematitization-limonitization and chloritization-kaolinization, and additionally by small spots and veinlets of pyrite and galena. It seems that tectonic control exists on the uranium mineralization, since most of the anomalous concentrations of uranium are sitting along mylonite zones rich in chlorite and kaolin. There have been discerned seven more anomalous part areas which will have to be covered by geochemical stream sediment sampling (phase 3), as well as geological mapping (scale 1:5.000). The results from the research conducted within the concerned anomaly lead us to the conclusion that this area is very promising and possibilities of localization of uranium payable concentrations are very high. (N.Ch.)

  12. The Geology And Geochemistry Of Zona Uranium Occurence, Upper Benue Trough; N.E. Nigeria.

    Energy Technology Data Exchange (ETDEWEB)

    Ogunleye, P O [Centre For Energy Research And Training, Ahmadu Bello University, Zaria (Nigeria); Okujeni, C D [Department Of Geology, Ahmadu Bello University, Zaria (Nigeria)

    1994-12-31

    The Zona uranium is located at the NE flank of the Peta syncline, which is an arm of the Middle Gongola Basin. The hostreok- the Cretaceous Bima sandstone bears the imprint of more than two preore tectonic episodes which are thought to have resulted from reactivation of paleolineaments in the basement since the Pan African Orogeny. The mineralized zone occurs at point of intersection of a set of NE-SW trending shear zone and N-S fracture system. The centre of the ore zone exhibits intense alteration features such as sericitization, ferruginization, silification, remobilization and powdering of the rock matrix. These alteration features diminish progressively from the core to the periphery of the ore zone. The main uraniferous minerals identified are phosphouranylite and meta-autunite. These occur mainly absorbed to iron oxides, in silicified veinlets and partly disseminated in the matrix of the sandstone. Evaluation of the analytical data of 9 elements in 67 rock samples suggest a close link between ferruginization and enrichment of uranium. A model involving the leaching of the uranium from conceal volcanics (rhyolites) and granites at depths by heated groundwater residual magmatic solutions is proposed.

  13. Influence of Uranium on Bacterial Communities: A Comparison of Natural Uranium-Rich Soils with Controls

    Science.gov (United States)

    Mondani, Laure; Benzerara, Karim; Carrière, Marie; Christen, Richard; Mamindy-Pajany, Yannick; Février, Laureline; Marmier, Nicolas; Achouak, Wafa; Nardoux, Pascal; Berthomieu, Catherine; Chapon, Virginie

    2011-01-01

    This study investigated the influence of uranium on the indigenous bacterial community structure in natural soils with high uranium content. Radioactive soil samples exhibiting 0.26% - 25.5% U in mass were analyzed and compared with nearby control soils containing trace uranium. EXAFS and XRD analyses of soils revealed the presence of U(VI) and uranium-phosphate mineral phases, identified as sabugalite and meta-autunite. A comparative analysis of bacterial community fingerprints using denaturing gradient gel electrophoresis (DGGE) revealed the presence of a complex population in both control and uranium-rich samples. However, bacterial communities inhabiting uraniferous soils exhibited specific fingerprints that were remarkably stable over time, in contrast to populations from nearby control samples. Representatives of Acidobacteria, Proteobacteria, and seven others phyla were detected in DGGE bands specific to uraniferous samples. In particular, sequences related to iron-reducing bacteria such as Geobacter and Geothrix were identified concomitantly with iron-oxidizing species such as Gallionella and Sideroxydans. All together, our results demonstrate that uranium exerts a permanent high pressure on soil bacterial communities and suggest the existence of a uranium redox cycle mediated by bacteria in the soil. PMID:21998695

  14. Geology and Uranium Mineralization of Tanah Merah and Dendang Arai Sectors, West Kalimantan

    International Nuclear Information System (INIS)

    Bambang-Soetopo

    2004-01-01

    Tanah Merah and Dendang Arai sectors are one of the mineralized sectors at Kalan. Goal of this study is to understand the relationship between geology and uranium mineralization character of Tanah Merah and Dendang Arai sectors. In general geology of Tanah Merah is similar with Dendang Arai which consist of biotite quartzite, leopard quartzite, muscovite quartzite, biotite muscovite quartzite, metasilt, metapelite, and granite. The folding is anticline with axel N45F in direction. The prominent fault is NE-SW sinistral fault, NW-SE dextral fault and N-S normal faults. U mineralization fills in the area space between minerals and also as the vein that fill in the fracture system W-E to WNW-ESE in direction. The thickness of mineralization is milimetric to centrimetric. Uranium minerals are uraninite, monazite, autunite and gummite associated with feldspar, tourmaline, zircon, biotite, quartz, pyrite, pyrhotite, hematite, rutile, chalcopyrite, magnenite ilmenite and molybdenite. Radiometric value is in the range of 1.000 to 15.000 c/s and the total grade of U are 12.6 to 2661.25 ppm. U mineralization process connected with intrusion of granite and in the secondary phase. (author)

  15. Effect of pH change on the primary uran-mica mineralization

    Energy Technology Data Exchange (ETDEWEB)

    Shmariovich, E M; Zhil' tsova, I G; Pakul' nis, G V; Shugina, G A [Ministerstvo Geologii SSR, Moscow

    1982-01-01

    Conditions of the formation of ore bodies of hexavalent uranium minerals represented by uranyl vanadates and phosphates which are primary and sedimented from low temperature solutions (carnotite deposits in calcretes and carnotite - autunite deposits in black shale formations) are considered. Thermodynamic curves of the solubility dependence of various uranyl minerals on pH medium in the absence of SO/sub 4//sup 2 -/ and CO/sub 3//sup 2 -/ ions and for sulphate-carbonate solutions have been calculated using dissociation constants of corresponding acids and ..delta..G/sup 0/f(298.15) values. It has been ascertained that uranyl mineral compounds according to the dependence of their solubility on ph medium form a distinct series from molybdates through arsenates, phosphates, vanadates and silicates to minerals of uranophane and kasolite group. It is shown that during the formation of infiltration deposits with uranyl mineralization a decisive role is played by the contrast change of pH value of medium caused by the presence of acid geochemical barrier (uranyl molybdates, arsenates, phosphates and vanadates are precipitating) or neutralizing alkaline barriers (uran-mica and uranyl silicates are precipitating) on the path of movement of oxygen metal-bearing solutions.

  16. Persistent U(IV) and U(VI) following in-situ recovery (ISR) mining of a sandstone uranium deposit, Wyoming, USA

    Science.gov (United States)

    Gallegos, Tanya J.; Campbell, Kate M.; Zielinski, Robert A.; Reimus, P.W.; J.T. Clay,; N. Janot,; J. J. Bargar,; Benzel, William M.

    2015-01-01

    Drill-core samples from a sandstone-hosted uranium (U) deposit in Wyoming were characterized to determine the abundance and distribution of uranium following in-situ recovery (ISR) mining with oxygen- and carbon dioxide-enriched water. Concentrations of uranium, collected from ten depth intervals, ranged from 5 to 1920 ppm. A composite sample contained 750 ppm uranium with an average oxidation state of 54% U(VI) and 46% U(IV). Scanning electron microscopy (SEM) indicated rare high uranium (∼1000 ppm U) in spatial association with P/Ca and Si/O attributed to relict uranium minerals, possibly coffinite, uraninite, and autunite, trapped within low permeability layers bypassed during ISR mining. Fission track analysis revealed lower but still elevated concentrations of U in the clay/silica matrix and organic matter (several 10 s ppm) and yet higher concentrations associated with Fe-rich/S-poor sites, likely iron oxides, on altered chlorite or euhedral pyrite surfaces (but not on framboidal pyrite). Organic C (mining, the likely sequestration of uranium within labile iron oxides following mining and sensitivity to changes in redox conditions requires careful attention during groundwater restoration.

  17. Uranium occurrence at Sao Teodosio farm, Currais Novos, Rio Grande do Norte, Brazil

    International Nuclear Information System (INIS)

    Favali, J.C.; Leal, J.R.L.V.

    1974-01-01

    The areas of certain radiometric anomalies discovered in Serido geosyncline were selected for intensive study because of the similarity of the geology to that of known uranium deposits in other parts of the world. The uranium mineralization at Sao Teodosio farm, near Currais Novos, RN, on the Serrinha anticline axis, occurs in alaskite similar to that at Rossing in Southwest Africa. The Rossing deposit is the best example of the model proposed by Armstrong (1974) as 'porphyry' uranium deposits. That uranium deposit presents low grade of uranium content, about 0,030% U 3 O 8 and hundred thousands tons of uranium oxide. At Sao Teodosio occurs 550 m.y. alaskitic pegmatitic granite and garnet-quartz-biotite-schists of Serido formation, Upper Precambrian. These older rocks are cut by diabases dykes of Upper Terciary age. Uranium mineralization is associated with pegmatitic granite bodies similar to dykes and sills. The most common uranium minerals are: uraninite, meta-autunite and uranophane. Oligoclase, microline and quartz are the most frequent minerals. Acessory minerals are magnetite, titanite and zircon. Uranium oxide content at Sao Teodosio is 0,023% and average thickness is 2,80 m [pt

  18. 300 Area Treatability Test: Laboratory Development of Polyphosphate Remediation Technology for In Situ Treatment of Uranium Contamination in the Vadose Zone and Capillary Fringe

    Energy Technology Data Exchange (ETDEWEB)

    Wellman, Dawn M.; Pierce, Eric M.; Bacon, Diana H.; Oostrom, Martinus; Gunderson, Katie M.; Webb, Samuel M.; Bovaird, Chase C.; Cordova, Elsa A.; Clayton, Eric T.; Parker, Kent E.; Ermi, Ruby M.; Baum, Steven R.; Vermeul, Vincent R.; Fruchter, Jonathan S.

    2008-09-30

    This report presents results from bench-scale treatability studies conducted under site-specific conditions to optimize the polyphosphate amendment for implementation of a field-scale technology demonstration to stabilize uranium within the 300 Area vadose and smear zones of the Hanford Site. The general treatability testing approach consisted of conducting studies with site sediment and under site conditions, to develop an effective chemical formulation and infiltration approach for the polyphosphate amendment under site conditions. Laboratory-scale dynamic column tests were used to 1) quantify the retardation of polyphosphate and its degradation products as a function of water content, 2) determine the rate of polyphosphate degradation under unsaturated conditions, 3) develop an understanding of the mechanism of autunite formation via the reaction of solid phase calcite-bound uranium and aqueous polyphosphate remediation technology, 4) develop an understanding of the transformation mechanism, the identity of secondary phases, and the kinetics of the reaction between uranyl-carbonate and -silicate minerals with the polyphosphate remedy under solubility-limiting conditions, and 5) quantify the extent and rate of uranium released and immobilized based on the infiltration rate of the polyphosphate remedy and the effect of and periodic wet-dry cycling on the efficacy of polyphosphate remediation for uranium in the vadose zone and smear zone.

  19. Preliminary report on the geology of uranium deposits in the Browns Park Formation in Moffat County, Colorado, and Carbon County, Wyoming

    International Nuclear Information System (INIS)

    Ormond, A.

    1957-06-01

    Uranium was first discovered in the Browns Park Formation in 1951 in the Miller Hill area of south-central Wyoming. Since that time economically important deposits in this formation have been discovered and developed in the Poison Basin of south-central Wyoming and in the Maybell area of northwest Colorado. The Browns Park is the youngest formation (Miocene) in the region and overlies older rocks with angular unconformity. The formation consists of a basal conglomerate, fluviatile, lacustrine, and eolian sandstones, and locally a few thin beds of clay, tuff, and algal limestone. The sandstones are predominantly fine- to medium-grained and consist of quartz grains, scattered black chert grains, and interstitial clay. The uranium deposits are of the sandstone-impregnation type and are not confined to specific stratigraphic horizons. The important ore minerals are autunite and uranophane in oxidized sandstones, and uraninite and coffinite in unoxidized sandstones. Uranium is often associated with limonite and calcium carbonate in concretionary forms. Woody material, thought to play an important part in the deposition of uranium in many sandstone-type deposits, is not present in the deposits of the Browns Park Formation. However, organic carbon in the form of petroleum and petroleum residues has been observed in association with uranium in both the Poison Basin and the Maybell areas

  20. Uranium Biominerals Precipitated by an Environmental Isolate of Serratia under Anaerobic Conditions

    Science.gov (United States)

    Newsome, Laura; Morris, Katherine; Lloyd, Jonathan. R.

    2015-01-01

    Stimulating the microbially-mediated precipitation of uranium biominerals may be used to treat groundwater contamination at nuclear sites. The majority of studies to date have focussed on the reductive precipitation of uranium as U(IV) by U(VI)- and Fe(III)-reducing bacteria such as Geobacter and Shewanella species, although other mechanisms of uranium removal from solution can occur, including the precipitation of uranyl phosphates via bacterial phosphatase activity. Here we present the results of uranium biomineralisation experiments using an isolate of Serratia obtained from a sediment sample representative of the Sellafield nuclear site, UK. When supplied with glycerol phosphate, this Serratia strain was able to precipitate 1 mM of soluble U(VI) as uranyl phosphate minerals from the autunite group, under anaerobic and fermentative conditions. Under phosphate-limited anaerobic conditions and with glycerol as the electron donor, non-growing Serratia cells could precipitate 0.5 mM of uranium supplied as soluble U(VI), via reduction to nano-crystalline U(IV) uraninite. Some evidence for the reduction of solid phase uranyl(VI) phosphate was also observed. This study highlights the potential for Serratia and related species to play a role in the bioremediation of uranium contamination, via a range of different metabolic pathways, dependent on culturing or in situ conditions. PMID:26132209

  1. Effect of natural uranium on the UMR-106 osteoblastic cell line: impairment of the autophagic process as an underlying mechanism of uranium toxicity.

    Science.gov (United States)

    Pierrefite-Carle, Valérie; Santucci-Darmanin, Sabine; Breuil, Véronique; Gritsaenko, Tatiana; Vidaud, Claude; Creff, Gaelle; Solari, Pier Lorenzo; Pagnotta, Sophie; Al-Sahlanee, Rasha; Auwer, Christophe Den; Carle, Georges F

    2017-04-01

    Natural uranium (U), which is present in our environment, exerts a chemical toxicity, particularly in bone where it accumulates. Generally, U is found at oxidation state +VI in its oxocationic form [Formula: see text] in aqueous media. Although U(VI) has been reported to induce cell death in osteoblasts, the cells in charge of bone formation, the molecular mechanism for U(VI) effects in these cells remains poorly understood. The objective of our study was to explore U(VI) effect at doses ranging from 5 to 600 µM, on mineralization and autophagy induction in the UMR-106 model osteoblastic cell line and to determine U(VI) speciation after cellular uptake. Our results indicate that U(VI) affects mineralization function, even at subtoxic concentrations (metal exposure. We observed that U(VI) was able to rapidly activate autophagy but an inhibition of the autophagic flux was observed after 24 h. Thus, our results indicate that U(VI) perturbs osteoblastic functions by reducing mineralization capacity. Our study identifies for the first time U(VI) in the form of meta-autunite in mammalian cells. In addition, U(VI)-mediated inhibition of the autophagic flux may be one of the underlying mechanisms leading to the decreased mineralization and the toxicity observed in osteoblasts.

  2. Natural analogue study of uranium deposits in Japan with special reference to the Tono uranium deposit

    International Nuclear Information System (INIS)

    Komuro, Kosei; Sasao, Eiji

    2004-05-01

    In order to verify the safety assessment for geological disposal system of high-level radioactive waste, it is necessary to evaluate properly the stability of the disposal system under natural hydrogeological environment over long period of time (ten to hundred thousands years). For the safety assessment for that in the Japanese Islands, many geological processes inherent in the tectonically active Island-Arc system should be also taken into consideration in addition to those in stable continental environment. However, it is difficult because some processes such as earthquake seem to be accidental and some are periodic or gradual over our life scale. The uranium deposits in Japan are subjected to many geological processes inherent in the tectonically active Island-Arc system. The studies on long-term preservation of uranium deposits in Japan from a natural analogue viewpoint would be expected to provide useful information for the assessment in the Japanese Islands over long period of time. In order to understand the behavior of radionuclides under natural hydrogeological environment in Japanese Islands over long period of time, the uranium deposits in Japan, especially of the Tono uranium deposit was investigated from a natural analogue viewpoint under the course of joint research program by University of Tsukuba and Japan Nuclear Cycle Development Institute. Important conclusions obtained in the present study are summarized as follows: The migration behavior of the radionuclides in the granite area is mainly controlled by the stability of original minerals in oxic condition, being due to poor reducing agents such as organic matter and sulfide minerals. In the case of hydrothermal alteration, yttrialite and fergusonite were decomposed and thorogummite was formed at the altered part, whereas zircon and allanite have not been significantly altered. In the case of weathering, autunite and torbernite were formed, probably due to the high phosphorus weathering

  3. Inventory of uranium potential sector at Tanah Merah (continuation), West Kalimantan, systematic prospection stage

    International Nuclear Information System (INIS)

    Subiantoro, L.; Sudarmadi; Sularto, P.; Widito, P.; Marzuki, A.; Paimin

    2000-01-01

    The investigation based on the previous study by CEA-BATAN (1977) and PPBGN-BATAN (1992-1994/1996), which was found radiometric anomalies on several outcrops (> 15.000 c/s) and soil (> 200 c/s). In again to find information of distribution, geometry and characteristically of mineralization zones, the systematic prospection was done by radiometric and topographic mapping and uranium geology aspect identification. Zones of mineralization were identified in Tanah Merah had total area 5468.4 m 2 . The outcrops of quarzitic rocks in this zone are characterized by vein distribution which contain uraninite, brannerite, autunite, gummite and gutite. The dominantly associated of their minerals are monazite, tourmaline, molybdenite, pirhotite, pyrite, ilmenite, sphalerite, chalcopyrite and hematite. By chips sampling in quarsite rock to appear of a lowest value is 8.45 ppm, highest 15259.73 ppm and average value is 319.9 to 489.5 ppm. Elements group correlation matrices from each rocks sample shows that the uranium had relatively good correlation with Cu, Pb, Zn, Co and Ni. The mineralized zone are consist of localized mineralization in lateral and vertically distribution. Structurally the mineralization exist in intersection WNW - ESE, NNE - SSw and WNW - ESE (sub horizontal) fracture. The mineralization are identified as vein type, granite related sub type, perigranitic class and polymetallic veins type, type deposits in metamorphic rocks sub class. (author)

  4. Bio-precipitation of uranium by two bacterial isolates recovered from extreme environments as estimated by potentiometric titration, TEM and X-ray absorption spectroscopic analyses.

    Science.gov (United States)

    Merroun, Mohamed L; Nedelkova, Marta; Ojeda, Jesus J; Reitz, Thomas; Fernández, Margarita López; Arias, José M; Romero-González, María; Selenska-Pobell, Sonja

    2011-12-15

    This work describes the mechanisms of uranium biomineralization at acidic conditions by Bacillus sphaericus JG-7B and Sphingomonas sp. S15-S1 both recovered from extreme environments. The U-bacterial interaction experiments were performed at low pH values (2.0-4.5) where the uranium aqueous speciation is dominated by highly mobile uranyl ions. X-ray absorption spectroscopy (XAS) showed that the cells of the studied strains precipitated uranium at pH 3.0 and 4.5 as a uranium phosphate mineral phase belonging to the meta-autunite group. Transmission electron microscopic (TEM) analyses showed strain-specific localization of the uranium precipitates. In the case of B. sphaericus JG-7B, the U(VI) precipitate was bound to the cell wall. Whereas for Sphingomonas sp. S15-S1, the U(VI) precipitates were observed both on the cell surface and intracellularly. The observed U(VI) biomineralization was associated with the activity of indigenous acid phosphatase detected at these pH values in the absence of an organic phosphate substrate. The biomineralization of uranium was not observed at pH 2.0, and U(VI) formed complexes with organophosphate ligands from the cells. This study increases the number of bacterial strains that have been demonstrated to precipitate uranium phosphates at acidic conditions via the activity of acid phosphatase. Copyright © 2011 Elsevier B.V. All rights reserved.

  5. Kinetic study of time-dependent fixation of U{sup VI} on biochar

    Energy Technology Data Exchange (ETDEWEB)

    Ashry, A. [Division of Agricultural and Environmental Sciences, School of Biosciences, University of Nottingham, Sutton Bonington, Leicestershire LE12 5RD (United Kingdom); Radiation Protection Department, Nuclear Research Centre, Egyptian Atomic Energy Authority, Cairo (Egypt); Bailey, E.H., E-mail: liz.bailey@nottingham.ac.uk [Division of Agricultural and Environmental Sciences, School of Biosciences, University of Nottingham, Sutton Bonington, Leicestershire LE12 5RD (United Kingdom); Chenery, S.R.N. [British Geological Survey, Nicker Hill, Keyworth, Nottingham NG12 5GG (United Kingdom); Young, S.D. [Division of Agricultural and Environmental Sciences, School of Biosciences, University of Nottingham, Sutton Bonington, Leicestershire LE12 5RD (United Kingdom)

    2016-12-15

    Biochar, a by-product from the production of biofuel and syngas by gasification, was tested as a material for adsorption and fixation of U{sup VI} from aqueous solutions. A batch experiment was conducted to study the factors that influence the adsorption and time-dependent fixation on biochar at 20 °C, including pH, initial concentration of U{sup VI} and contact time. Uranium (U{sup VI}) adsorption was highly dependent on pH but adsorption on biochar was high over a wide range of pH values, from 4.5 to 9.0, and adsorption strength was time-dependent over several days. The experimental data for pH > 7 were most effectively modelled using a Freundlich adsorption isotherm coupled to a reversible first order kinetic equation to describe the time-dependent fixation of U{sup VI} within the biochar structure. Desorption experiments showed that U{sup VI} was only sparingly desorbable from the biochar with time and isotopic dilution with {sup 233}U{sup VI} confirmed the low, or time-dependent, lability of adsorbed {sup 238}U{sup VI}. Below pH 7 the adsorption isotherm trend suggested precipitation, rather than true adsorption, may occur. However, across all pH values (4.5-9) measured saturation indices suggested precipitation was possible: autunite below pH 6.5 and either swartzite, liebigite or bayleyite above pH 6.5.

  6. Geologic and radiometric study in the Picacho, Arizpe's Municipality, Sorora (Mexico) area

    International Nuclear Information System (INIS)

    Garcia y Barragan, J.C.

    1975-01-01

    This research work was aimed chiefly at studying the geology and radiometry of the El Picacho area in order to establish its uranium mineralization potential. Another purpose was to ascertain the factors favouring deposition of radioactive material in areas bordering on the Sierra del Manzanal, where the work was carried out. Detailed geological-radiometric surveys were made, both inside the El Picacho mine and at the surface. The geological surveys were carried out by means of compass bearings and stadia, while scintillometers and spectrometers were used for the radiometric studies. The work was supported by a general geological exploration of the central part of the Serra del Manzanal. To ascertain the radiometric anomalies, the distribution of the population of values was determined by statistical methods, the frequency, cumulative frequency and frequency percentage being evaluated for that purpose. The geological survey at the El Picacho mine revealed a group of fractures enclosing the following minerals: torbernite, iriginite and autunite. These fractures are no thicker than 5 cm and tend to wedge out after 3 meters. Primary uraniferous ore is likely to be found in this zone, so surveys based on (a) radon gas emanometry and (b) sediment geochemistry in the Siera del Manzanal are recommended. The basic data relating to this area could be supplemented by mineragraphic and X-ray studies, which would provide a fuller picture of the class of mineralogical species and of the paragenesis of radioactive material presnent in the zone. (author)

  7. REMEDIATION OF THE SERBIAN SOILS CONTAMINATED BY RADIONUCLIDES IN THE FUNCTION OF THE SUSTAINABLE DEVELOPMENT

    Directory of Open Access Journals (Sweden)

    M. Stojanović

    2008-11-01

    Full Text Available Phosphate-induced metal stabilization (PIMS using apatite stabilizes uranium in situ, by chemically binding it into the new low-solubility (Ksp=10-49 phase. Uranium-phosphate-autunite is stable across a wide range of geological conditions for millions of years. A large area of contaminated soil is suitable for insitu remediation that involves minimizing the mobility of the uranium. Laboratory study was conducted to quantify different forms of apatite sequestration of uranium contaminant. The experiment was done with natural phosphate from Lisina deposit (14.43 % P2O5, with non-treated samples, phosphate concentrate samples with 34.95 % P2O5 and mechanochemically activated of natural apatite. Different concentration of P2O5 in apatite, pH, reaction time, solid/liquid ratio was investigated. The concentrate at pH 5.5 for 7 days sorbed around 93,64 % and nature apatite, with 14,43 % P2O5, for 30 days sorbed 94.54 % of the uranium from the water solution, concentration 100 μg U/ml. The results show that mineral apatite “Lisina” is very effective for the treatment of contaminated soils - in situ immobilization of U. Mechanochemical activation of natural apatite in vibration mill immobilized 85.37 % of uranium in the 7-day period of acting. This research on natural apatite from the deposit “Lisina” for immobilization of uranium was the first one of this type in our country.

  8. Geology of the uranium occurrence in the Bungua area, Siavonga District, Zambia

    International Nuclear Information System (INIS)

    Prasad, R.S.; Money, N.J.; Thieme, J.G.

    1979-01-01

    Uranium mineralization related to the fluviatile continental sandstone of the Escarpment Grit Formation of Upper Karroo System has been studied in detail in the Bungua area. Airborne and ground gamma-radiation surveys resulted in the discovery of mineralized bodies containing secondary minerals such as meta-autunite, phosphuranylite, uranocircite, abernythite, boltwoodite, etc. disseminated in various ways. Geological, radiometric, stratigraphic, sedimentological and petrological studies coupled with exploration pitting, trenching and drilling were employed to assess the nature, distribution and sub-surface continuation of mineralized bodies. Drilling, logging and XRF analysis revealed that the uranium mineralized bodies are mainly lenses at different levels, which may be concordant or discordant with bedding. The thickness and grade of ore horizons differ considerably. Mineral distribution and controls are complex and that the main deposit is controlled by reducing lithologies, organic matter, clay traps, micas, iron cementing and permeable channels. Although no definite mode of origin can be attributed to the presently seen uranium mineralized bodies, they appear to be from a pre-existing ore deposit which is mobilized and redistributed during oxidation by supergene processes. It is suggested that the original uranium was in solution as uranylion and came from the same source area as the host rocks and the uranium-bearing groundwater and streams moved in the same direction as the associated Escarpment Grit sediments. Uranium was precipitated wherever favourable conditions prevailed in the Escarpment Grit Formation. (author)

  9. Contact metamorphic effects of the basic intrusive rocks on the Proterozoic uraniferous dolostone in Cuddapah basin, Andhra Pradesh: implications on uranium mobilisation

    International Nuclear Information System (INIS)

    Roy, Minati; Panda, Arjuna; Dhana Raju, R.

    1997-01-01

    Mafic intrusive rocks in the Vempalle formation of the mid-Proterozoic Cuddapah basin occur as sills and dykes. These include minor bodies of gabbro, olivine gabbro, olivine norite, basalt and mainly dolerite with basaltic andesite. The metamorphic effects of these intrusive rocks on the uraniferous phosphatic siliceous dolostone are mainly mineralogical (thermal) with subordinate changes in chemistry. These are manifested by (a) formation of plagioclase-hornblende hornfels, (b) notable mineralogical changes in the dolostone leading to enrichment of magnetite, epidote, anatase and de-dolomitised calcite, (c) decrease in specific gravity of dolostone from 3.0 to 2.8 due to volatilisation reaction products of epidote and smectite, and (d) formation of wollastonite, chalcedony, and secondary uranium minerals (autunite and uranophane) at places, in the contact aureole that led to notable changes in the chemistry of the intrusive body and the host rock. Intrusive rocks at the contact show enrichment in Fe 2+ , Mg, Cu, Cr, Pb, Zn, Ni, and depletion in Ca and Fe 3+ , whereas the dolostone shows enrichment in Ti, Ca, and depletion in Si, Al, alkalies and P. Depletion of uranium in the affected parts (0.003% U 3 O 8 ) of mineralised dolostone (0.062% U 3 O 8 ) adjacent to the basic intrusive rocks suggests its mobilisation, due to increase in temperature, resulting in baking. This phenomenon is also manifested, at places, in the formation of secondary uranium minerals - result of remobilisation of uranium from primary phases and its subsequent precipitation. (author)

  10. Kinetic study of time-dependent fixation of U"V"I on biochar

    International Nuclear Information System (INIS)

    Ashry, A.; Bailey, E.H.; Chenery, S.R.N.; Young, S.D.

    2016-01-01

    Biochar, a by-product from the production of biofuel and syngas by gasification, was tested as a material for adsorption and fixation of U"V"I from aqueous solutions. A batch experiment was conducted to study the factors that influence the adsorption and time-dependent fixation on biochar at 20 °C, including pH, initial concentration of U"V"I and contact time. Uranium (U"V"I) adsorption was highly dependent on pH but adsorption on biochar was high over a wide range of pH values, from 4.5 to 9.0, and adsorption strength was time-dependent over several days. The experimental data for pH > 7 were most effectively modelled using a Freundlich adsorption isotherm coupled to a reversible first order kinetic equation to describe the time-dependent fixation of U"V"I within the biochar structure. Desorption experiments showed that U"V"I was only sparingly desorbable from the biochar with time and isotopic dilution with "2"3"3U"V"I confirmed the low, or time-dependent, lability of adsorbed "2"3"8U"V"I. Below pH 7 the adsorption isotherm trend suggested precipitation, rather than true adsorption, may occur. However, across all pH values (4.5-9) measured saturation indices suggested precipitation was possible: autunite below pH 6.5 and either swartzite, liebigite or bayleyite above pH 6.5.

  11. Uranium prospecting; La prospection de l'uranium

    Energy Technology Data Exchange (ETDEWEB)

    Roubault, M [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1955-07-01

    This report is an instruction book for uranium prospecting. It appeals to private prospecting. As prospecting is now a scientific and technical research, it cannot be done without preliminary studies. First of all, general prospecting methods are given with a recall of fundamental geologic data and some general principles which are common with all type of prospecting. The peculiarities of uranium prospecting are also presented and in particular the radioactivity property of uranium as well as the special aspect of uranium ores and the aspect of neighbouring ores. In a third part, a description of the different uranium ores is given and separated in two different categories: primary and secondary ores, according to the place of transformation, deep or near the crust surface respectively. In the first category, the primary ores include pitchblende, thorianite and rare uranium oxides as euxenite and fergusonite for example. In the second category, the secondary ores contain autunite and chalcolite for example. An exhaustive presentation of the geiger-Mueller counter is given with the presentation of its different components, its functioning and utilization and its maintenance. The radioactivity interpretation method is showed as well as the elaboration of a topographic map of the measured radioactivity. A brief presentation of other detection methods than geiger-Mueller counters is given: the measurement of fluorescence and a chemical test using the fluorescence properties of uranium salts. Finally, the main characteristics of uranium deposits are discussed. (M.P.)

  12. Uranium prospecting; La prospection de l'uranium

    Energy Technology Data Exchange (ETDEWEB)

    Roubault, M. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1955-07-01

    This report is an instruction book for uranium prospecting. It appeals to private prospecting. As prospecting is now a scientific and technical research, it cannot be done without preliminary studies. First of all, general prospecting methods are given with a recall of fundamental geologic data and some general principles which are common with all type of prospecting. The peculiarities of uranium prospecting are also presented and in particular the radioactivity property of uranium as well as the special aspect of uranium ores and the aspect of neighbouring ores. In a third part, a description of the different uranium ores is given and separated in two different categories: primary and secondary ores, according to the place of transformation, deep or near the crust surface respectively. In the first category, the primary ores include pitchblende, thorianite and rare uranium oxides as euxenite and fergusonite for example. In the second category, the secondary ores contain autunite and chalcolite for example. An exhaustive presentation of the geiger-Mueller counter is given with the presentation of its different components, its functioning and utilization and its maintenance. The radioactivity interpretation method is showed as well as the elaboration of a topographic map of the measured radioactivity. A brief presentation of other detection methods than geiger-Mueller counters is given: the measurement of fluorescence and a chemical test using the fluorescence properties of uranium salts. Finally, the main characteristics of uranium deposits are discussed. (M.P.)

  13. Solubility and dissolution kinetics study of uranium phosphates and vanadates: implications for the front end of the electronuclear cycle

    International Nuclear Information System (INIS)

    Cretaz, F.

    2013-01-01

    In the current context of restart of the nuclear energy, the needs in uranium are expected to increase significantly. Moreover, in a perspective of sustainable development, the exploitation, the treatment and the purification of uranium ores need to be optimized. It is thus necessary to determine reliable thermodynamic data (and especially solubility constants) for the systems of interest, especially uranium(VI) phosphates and vanadates. In this aim, a multi parametric study of the dissolution of meta-torbernite Cu 0.8 (H 3 O) 0.2 (UO 2 ) 2 (PO 4 ) 2.8 H 2 O, meta-autunite Ca(UO 2 ) 2 (PO 4 ) 2.6 H 2 O, meta-ankoleite K 2 (UO 2 ) 2 (PO 4 ) 2.6 H 2 O and carnotite K 2 (UO 2 ) 2 (VO 4 ) 2.3 H 2 O was undertaken. First, analogues of these four minerals were synthesized, based only on dry chemistry process for carnotite or on wet chemistry methods for the phosphate phases. They were then extensively characterized (in terms of structure, microstructure and chemical composition). It particularly highlighted the similar structures of such compounds. The anionic groups (PO 4 3- or V 2 O 8 6- ) and uranyl form parallel layers between which counter cations (Cu 2+ , Ca 2+ or K + ) and water molecules are inserted. However, the counter cations present in the interlayer space of the three phosphate phases present different lability. The synthetic phases were also compared to their natural analogues, except for meta-ankoleite, which allowed us to point out significant differences in the composition (presence of impurities in natural samples) and the morphology (grain size). The dissolution of these phases was then studied from a kinetic and thermodynamic point of view, through leaching tests in static and dynamic conditions, in various acid media (sulfuric, nitric and hydrochloric) and at different temperatures. In these conditions, the dissolution of meta-autunite was found to be un-congruent due to the precipitation of uranyl phosphate then avoiding the determination of

  14. Phosphate-induced metal stabilization: Use of apatite and bone char for the removal of soluble radionuclides in authentic and simulated DOE groundwater

    International Nuclear Information System (INIS)

    Bostick, W.D.; Jarabek, R.J.; Conca, J.L.

    1999-01-01

    The apatite group of minerals is a family of calcium phosphate phases. Apatite is the principal component of bone tissue, and it also occurs naturally as mineral deposits in the geosphere. Bone char is calcined (coked) animal bone, containing activated carbon as well as calcium phosphate mineral phases. Apatite IItrademark is a more reactive form of apatite, supplied by UFA Ventures, Inc., at a cost of approximately 1/4 that of commercial bone char. Apatite is shown to be effective for the removal of select heavy metal impurities in groundwater. Previous investigations have demonstrated that apatite is an effective medium for the stabilization of soluble lead, cadmium, and zinc from mine waste leachate by the formation of highly insoluble precipitate phases. The performance of bone char and apatite II are compared with other candidate sorption media (including granular activated carbon and anion exchange resin) for the removal of soluble uranyl ion in synthetic DOE Site groundwater supplemented with varying levels of interfering nitrate ion. Apatite II has a greater affinity for U(VI), especially in the presence of nitrate ion, as evidenced by a larger value for the conditional distribution coefficient (Kd) in batch test experiments. Contact of uranyl nitrate solution with apatite II is shown to produce highly insoluble mineral phases of the autunite group (calcium uranyl phosphate hydrates). Apatite II is also demonstrated to be moderately effective for the removal of soluble radioactive isotopes of strontium, but not cesium, when these ions are supplemented into authentic DOE Site groundwater

  15. International Uranium Resources Evaluation Project (IUREP) national favourability studies: Belgium

    International Nuclear Information System (INIS)

    1977-12-01

    Uranium occurrences and resources - To date the uranium identified in Belgium is limited to a number of occurrences and none of these have as yet proved significant from a reserve or resource viewpoint. The main uranium occurrences ares (1) In the Upper Cambrian graphite schists corresponding to the culm of Sweden small zones are found (30 - 50 cm thick) with an average of 20 ppm uranium. (2) Near Vise at the base of the Carboniferous the Visean formation is discordantly superimposed on the Permian (Frasnian) and overlain by shales and phyllites. Solution pockets at the boundary contain phosphatic lenses that contain uranium values of up to 200 ppm. Autunite and Torbernite are the main uranium minerals associated with a number of complex phosphatic minerals. Within the Chalk (Maestrichtien) of the Mons basin, that is mainly in the Ciply - St. Symphorien and Baudow district. Here is found enrichment of uranium up to 140 ppm over large areas related to phosphatic chalk. The thickness of the zone varies from a few to 20 metres. However, as the P 2 O 5 content is not high enough for the deposits to be exploited at present for phosphate there is little possibility of the uranium being concentrated at high enough levels to be exploited for itself alone. (4) Near to Vielsalm (in the Stavelot Massif) are some thin quartz veins containing small amounts of copper and uranium minerals (Torbornite). Values of up to 70 ppm are recorded. (5) A number of low uranium values are recorded associated with phosphatic nodules and zones in the Lower Pleistocene and Tertiary

  16. Bio-precipitation of uranium by two bacterial isolates recovered from extreme environments as estimated by potentiometric titration, TEM and X-ray absorption spectroscopic analyses

    Energy Technology Data Exchange (ETDEWEB)

    Merroun, Mohamed L., E-mail: merroun@ugr.es [Institute of Radiochemistry, Helmholtz Centre Dresden-Rossendorf, Dresden (Germany); Departamento de Microbiologia, Universidad de Granada, Campus Fuentenueva s/n 18071, Granada (Spain); Nedelkova, Marta [Institute of Radiochemistry, Helmholtz Centre Dresden-Rossendorf, Dresden (Germany); Ojeda, Jesus J. [Cell-Mineral Interface Research Programme, Kroto Research Institute, University of Sheffield, Broad Lane, Sheffield S3 7HQ (United Kingdom); Experimental Techniques Centre, Brunel University, Uxbridge, Middlesex UB8 3PH (United Kingdom); Reitz, Thomas [Institute of Radiochemistry, Helmholtz Centre Dresden-Rossendorf, Dresden (Germany); Fernandez, Margarita Lopez; Arias, Jose M. [Departamento de Microbiologia, Universidad de Granada, Campus Fuentenueva s/n 18071, Granada (Spain); Romero-Gonzalez, Maria [Cell-Mineral Interface Research Programme, Kroto Research Institute, University of Sheffield, Broad Lane, Sheffield S3 7HQ (United Kingdom); Selenska-Pobell, Sonja [Institute of Radiochemistry, Helmholtz Centre Dresden-Rossendorf, Dresden (Germany)

    2011-12-15

    Highlights: Black-Right-Pointing-Pointer Precipitation of uranium as U phosphates by natural bacterial isolates. Black-Right-Pointing-Pointer The uranium biomineralization involves the activity of acidic phosphatase. Black-Right-Pointing-Pointer Uranium bioremediation could be achieved via the biomineralization of U(VI) in phosphate minerals. - Abstract: This work describes the mechanisms of uranium biomineralization at acidic conditions by Bacillus sphaericus JG-7B and Sphingomonas sp. S15-S1 both recovered from extreme environments. The U-bacterial interaction experiments were performed at low pH values (2.0-4.5) where the uranium aqueous speciation is dominated by highly mobile uranyl ions. X-ray absorption spectroscopy (XAS) showed that the cells of the studied strains precipitated uranium at pH 3.0 and 4.5 as a uranium phosphate mineral phase belonging to the meta-autunite group. Transmission electron microscopic (TEM) analyses showed strain-specific localization of the uranium precipitates. In the case of B. sphaericus JG-7B, the U(VI) precipitate was bound to the cell wall. Whereas for Sphingomonas sp. S15-S1, the U(VI) precipitates were observed both on the cell surface and intracellularly. The observed U(VI) biomineralization was associated with the activity of indigenous acid phosphatase detected at these pH values in the absence of an organic phosphate substrate. The biomineralization of uranium was not observed at pH 2.0, and U(VI) formed complexes with organophosphate ligands from the cells. This study increases the number of bacterial strains that have been demonstrated to precipitate uranium phosphates at acidic conditions via the activity of acid phosphatase.

  17. Microbial diversity in opalinus clay and interaction of dominant microbial strains with actinides

    International Nuclear Information System (INIS)

    Moll, Henry; Luetke, Laura; Bachvarova, Velina; Steudtner, Robin; Geissler, Andrea; Krawczyk-Baersch, Evelyn; Selenska-Pobell, Sonja; Bernhardt, Gert

    2013-01-01

    For the first time microbial tDNA could be isolated from 50 g unperturbed Mont Terri Opalinus Clay. Based on the analysis of the tDNA the bacterial diversity of the unperturbed clay is dominated by representatives of Firmicutes, Betaproteobacteria, and Bacteriodetes. Firmicutes also dominate after treatment of the clay with R2A medium. Bacteria isolated from Mont Terri Opalinus Clay on R2A medium were related to Sporomusa spp., Paenibacillus spp., and Clostridium spp. All further investigations are concentrated on the unique isolates Sporomusa sp. MT-2 and Paenibacillus sp. MT-2. Cells of the type Sporomusa sp. MT-2 and Paenibacillus sp. MT-2 were comprehensively analyzed in terms of growing, morphology, functional groups of the cell envelope, and cell membrane structure. Strong actinide(An)/lanthanide(Ln)-interactions with the Opalinus Clay isolates and the Aespoe-strain Pseudomonas fluorescens (CCUG 32456) could be determined within a broad pH range (2-8). The metals bind as a function of pH on protonated phosphoryl, carboxyl and deprotonated phosphoryl sites of the respective cell membrane. The thermodynamic surface complexation constants of bacterial An/Ln-species were determined and can be used in modeling programs. Depending on the used An different interaction mechanisms were found (U(VI): biosorption, partly biomineralisation; Cm(III): biosorption, indications for embedded Cm(III); Pu: biosorption, bioreduction and indications for embedded Pu). Different strategies of coping with U(VI) were observed comparing P. fluorescens planktonic cells and biofilms under the chosen experimental conditions. An enhanced capability of the biofilm to form meta-autunite in comparison to the planktonic cells was proven. Conclusively, the P. fluorescens biofilm is more efficient in U(VI) detoxification. In conclusion, Mont Terri Opalinus Clay contains bacterial communities, that may influence the speciation and hence the migration behavior of selected An/Ln under

  18. Microbial diversity in opalinus clay and interaction of dominant microbial strains with actinides

    Energy Technology Data Exchange (ETDEWEB)

    Moll, Henry; Luetke, Laura; Bachvarova, Velina; Steudtner, Robin; Geissler, Andrea; Krawczyk-Baersch, Evelyn; Selenska-Pobell, Sonja; Bernhardt, Gert

    2013-07-01

    For the first time microbial tDNA could be isolated from 50 g unperturbed Mont Terri Opalinus Clay. Based on the analysis of the tDNA the bacterial diversity of the unperturbed clay is dominated by representatives of Firmicutes, Betaproteobacteria, and Bacteriodetes. Firmicutes also dominate after treatment of the clay with R2A medium. Bacteria isolated from Mont Terri Opalinus Clay on R2A medium were related to Sporomusa spp., Paenibacillus spp., and Clostridium spp. All further investigations are concentrated on the unique isolates Sporomusa sp. MT-2 and Paenibacillus sp. MT-2. Cells of the type Sporomusa sp. MT-2 and Paenibacillus sp. MT-2 were comprehensively analyzed in terms of growing, morphology, functional groups of the cell envelope, and cell membrane structure. Strong actinide(An)/lanthanide(Ln)-interactions with the Opalinus Clay isolates and the Aespoe-strain Pseudomonas fluorescens (CCUG 32456) could be determined within a broad pH range (2-8). The metals bind as a function of pH on protonated phosphoryl, carboxyl and deprotonated phosphoryl sites of the respective cell membrane. The thermodynamic surface complexation constants of bacterial An/Ln-species were determined and can be used in modeling programs. Depending on the used An different interaction mechanisms were found (U(VI): biosorption, partly biomineralisation; Cm(III): biosorption, indications for embedded Cm(III); Pu: biosorption, bioreduction and indications for embedded Pu). Different strategies of coping with U(VI) were observed comparing P. fluorescens planktonic cells and biofilms under the chosen experimental conditions. An enhanced capability of the biofilm to form meta-autunite in comparison to the planktonic cells was proven. Conclusively, the P. fluorescens biofilm is more efficient in U(VI) detoxification. In conclusion, Mont Terri Opalinus Clay contains bacterial communities, that may influence the speciation and hence the migration behavior of selected An/Ln under

  19. Laboratory and in situ determination of the migration processes of actinide complexes and colloids in a fissured granitic environment. El Berrocal project (preliminary activities - phase 0)

    International Nuclear Information System (INIS)

    Astudillo, J.; Del Olmo, C.; Commission of the European Communities, Ispra

    1993-01-01

    The experimental site of El Berrocal has been chosen for a study of the migration of natural radionuclides in a fractured granitic environment. The granite is classified as an alkaline feldspar-rich quartz granite with two micas. The fresh granite is affected by hydrothermal alteration processes related to fractures, which has led to a strong sericitization of albite, and the precipitation of secondary chlorites and carbonates. The most important U-bearing and Th-bearing accessory minerals are uraninite, thorite-auerlite, monazite, anatase, apatite and zircon. Approximately 65% of the total of U in the rock is held as uraninite. In the altered granite, most of the U is held as autunite. Hydrogeochemical data show that Co 2 /H 2 CO 3 is the dominant system, followed by the silica-silicate system. Based on their stability analyses, two zones can be defined: (i) waters north of the dyke and from deep zones where calcite is in equilibrium and albite and gibbsite precipitate, and (ii) surface waters, south of the dyke, subsaturated in relation to calcite, producing the alteration of albite and the precipitation of montmorillonite. The size distribution of the colloids varies, depending on the treatment given to the water samples. The particles are mainly composed of K-feldspars and clay minerals (smectite) and occasionally by quartz, mica, calcite and pollen. The El Berrocal groundwaters have a very low amount of organic matter. Column migration tests have been carried out and were performed with intact granitic cores and with crushed granite. Np proved to be an adequate radionuclide for these experiments. Under oxic conditions and in the absence of organic matter, it was completely retained in both types of columns, whereas in the presence of organic matter a more rapid breakthrough was observed. Under anoxic conditions, and with or without organic matter, Np was found to move faster than under oxic conditions. (author). 13 refs., 46 figs., 23 tabs

  20. Potential toxic elements in stream sediments, soils and waters in an abandoned radium mine (central Portugal).

    Science.gov (United States)

    Antunes, I M H R; Neiva, A M R; Albuquerque, M T D; Carvalho, P C S; Santos, A C T; Cunha, Pedro P

    2018-02-01

    The Alto da Várzea radium mine (AV) exploited ore and U-bearing minerals, such as autunite and torbernite. The mine was exploited underground from 1911 to 1922, closed in 1946 without restoration, and actually a commercial area is deployed. Stream sediments, soils and water samples were collected between 2008 and 2009. Stream sediments are mainly contaminated in As, Th, U and W, which is related to the AV radium mine. The PTEs, As, Co, Cr, Sr, Th, U, W, Zn, and electrical conductivity reached the highest values in soils collected inside the mine influence. Soils are contaminated with As and U and must not be used for any purpose. Most waters have pH values ranging from 4.3 to 6.8 and are poorly mineralized (EC = 41-186 µS/cm; TDS = 33-172 mg/L). Groundwater contains the highest Cu, Cr and Pb contents. Arsenic occurs predominantly as H 2 (AsO 4 ) - and H(AsO 4 ) 2- . Waters are saturated in goethite, haematite and some of them also in lepidocrocite and ferrihydrite, which adsorbs As (V). Lead is divalent in waters collected during the warm season, being mobile in these waters. Thorium occurs mainly as Th(OH) 3 (CO 3 ) - , Th(OH) 2 (CO 3 ) and Th(OH) 2 (CO 3 ) 2 2- , which increase water Th contents. Uranium occurs predominantly as UO 2 CO 3 , but CaUO 2 (CO 3 ) 3 2- and CaUO 2 (CO 3 ) 3 also occur, decreasing its mobility in water. The waters are contaminated in NO 2 - , Mn, Cu, As, Pb and U and must not be used for human consumption and in agricultural activities. The water contamination is mainly associated with the old radium mine and human activities. A restoration of the mining area with PTE monitoring is necessary to avoid a public hazard.

  1. Geochemistry and mineralogy of the radioactive minerals associated with some pegmatite veins of the Ukma-Nawahatu Hursi sector, Purulia district, W.B., in the Precambrian Chhotanagpur Gneissic complex

    International Nuclear Information System (INIS)

    Baidya, Tapan Kumar

    2014-01-01

    Some barite-bearing pegmatites in the Ukma-Nawahatu-Hursi sector (23° 25 min - 26 sec N, 86° 02 min - 04 sec E) in Purulia dist., West Bengal, have association of radioactive minerals in the form of coarse-grained pitchblack lumps and irregular patches. The present author and his associates first reported the occurrence of this radioactive belt along a ENE-WSW shearzone during their fieldwork in November, 1978. Groundborne radiometric survey and isorad mapping has established a radioactive high zone of about 15 km length running through Ukma, Nawahatu and Hursi areas. Mineralogical studies of the radioactive minerals have revealed the occurrence of Chevkinite, Aeschynite, Brannerite, Allanite, Uraninite, Tyuyamunite, Davidite, Euxenite, Samarskite, Thorutite, Autunite, Cerianite, in association with quartz, barite, microcline as the principal minerals and various minor minerals like biotite, vermiculite, hornblende, augite, orthoclase, celsian, muscovite, calcite, epidote, zoisite, ilmenite, sphene, rutile, hematite, magnetite, anatase, galena and sodic plagioclase. The barite-bearing pegmatites occur as lenses or lenticular veins hosted by garnetiferous sillimanite-biotite-quartz-schist or occasionally by migmatite. Near Nawahatu the radioactive barite-pegmatite vein occurs at or near the junction between the footwall amphibolite and hangingwall garnetiferous schist. The pegmatite veins have followed mainly schistosity of the host rock and dip at 70°-80° towards south. Chemical analyses of individual radioactive minerals by SEM-EDX and also of the bulk radioactive lumps by ICP-MS have shown significant concentration of U, Tb and Rare earths. Minor and trace element analyses also record notable contents of Zr, Ga, Sc, Pb, Zn, Nb, Cu, Ni, V, Cr, As, W, Pd, Ag and TI. Details of chemical analytical data are presented here. Chemically active fluids generated during metamorphism, metasomatism and granitic activity appear to have played a significant role in the

  2. Geochemical modelling of the weathering zone of the 'Mina Fe' U deposit (Spain): A natural analogue for nuclear spent fuel alteration and stability processes in radwaste disposal

    International Nuclear Information System (INIS)

    Arcos, D.; Perez del Villar, L.; Bruno, J.; Domenech, C.

    2008-01-01

    The 'Mina Fe' U deposit (Salamanca, Spain) has been studied in the context of Enresa's programme for U-mine sites restoration and also as a natural analogue for processes in high-level nuclear waste (HLNW) geological disposal. The investigations encompassed an array of geoscience disciplines, such as structural geology, mineralogy, hydrogeology and elemental and isotopic geochemistry and hydrogeochemistry of the site. Based on the obtained results, a conceptual mineralogical and geochemical model was performed integrating the main geochemical processes occurring at the site: the interaction between oxidised and slightly acidic water with pyrite, pitchblende, calcite and dolomite, as essential minerals of the U fracture-filling mineralisation, and hydroxyapatite from the host rock, as the main source of P. This conceptual model has been tested in a systematic numerical model, which includes the main kinetic (pyrite and pitchblende dissolution) and equilibrium processes (carbonate mineral dissolution, and goethite, schoepite and autunite secondary precipitation). The results obtained from the reactive-transport model satisfactorily agree with the conceptual model previously established. The assumption of the precipitation of coffinite as a secondary mineral in the system cannot be correctly evaluated due to the lack of hydrochemical data from the reducing zone of the site and valid thermodynamic and kinetic data for this hydrated U(IV)-silicate. This precipitation can also be hampered by the probable existence of dissolved U(IV)-organic matter and/or uranyl carbonate complexes, which are thermodynamically stable under the alkaline and reducing conditions that prevail in the reducing zone of the system. Finally, the intense downwards oxic and acidic alteration in the upper part of the system is of no relevance for the performance assessment of a HLNW disposal. However, the acidic and oxidised conditions are quickly buffered to neutral-alkaline and reducing at very

  3. Geochemical modelling of the weathering zone of the 'Mina Fe' U deposit (Spain): A natural analogue for nuclear spent fuel alteration and stability processes in radwaste disposal

    Energy Technology Data Exchange (ETDEWEB)

    Arcos, D. [AMPHOS XXI Consulting S.L., Passeig de Rubi, 29-31, 08197 Valldoreix, Barcelona (Spain)], E-mail: david.arcos@amphos21.com; Perez del Villar, L. [CIEMAT, Dpto.de Medio Ambiente, Avda, Complutense 22, 28040 Madrid (Spain); Bruno, J.; Domenech, C. [AMPHOS XXI Consulting S.L., Passeig de Rubi, 29-31, 08197 Valldoreix, Barcelona (Spain)

    2008-04-15

    The 'Mina Fe' U deposit (Salamanca, Spain) has been studied in the context of Enresa's programme for U-mine sites restoration and also as a natural analogue for processes in high-level nuclear waste (HLNW) geological disposal. The investigations encompassed an array of geoscience disciplines, such as structural geology, mineralogy, hydrogeology and elemental and isotopic geochemistry and hydrogeochemistry of the site. Based on the obtained results, a conceptual mineralogical and geochemical model was performed integrating the main geochemical processes occurring at the site: the interaction between oxidised and slightly acidic water with pyrite, pitchblende, calcite and dolomite, as essential minerals of the U fracture-filling mineralisation, and hydroxyapatite from the host rock, as the main source of P. This conceptual model has been tested in a systematic numerical model, which includes the main kinetic (pyrite and pitchblende dissolution) and equilibrium processes (carbonate mineral dissolution, and goethite, schoepite and autunite secondary precipitation). The results obtained from the reactive-transport model satisfactorily agree with the conceptual model previously established. The assumption of the precipitation of coffinite as a secondary mineral in the system cannot be correctly evaluated due to the lack of hydrochemical data from the reducing zone of the site and valid thermodynamic and kinetic data for this hydrated U(IV)-silicate. This precipitation can also be hampered by the probable existence of dissolved U(IV)-organic matter and/or uranyl carbonate complexes, which are thermodynamically stable under the alkaline and reducing conditions that prevail in the reducing zone of the system. Finally, the intense downwards oxic and acidic alteration in the upper part of the system is of no relevance for the performance assessment of a HLNW disposal. However, the acidic and oxidised conditions are quickly buffered to neutral-alkaline and

  4. Exploration for sandstone- type uranium mineralisation in the Siwaliks of northwestern Himalaya, India

    International Nuclear Information System (INIS)

    Swarnkar, B.M.; Kothari, P.K.; Umamaheswar, K.; Srinivasan, S.

    2002-01-01

    The Siwalik Group with a thickness of about 6000m of fluvial sediments of middle Miocene to Pleistocene age has been explored extensively over two decades for U, using various types of exploration techniques involving air-borne gamma-ray spectrometry, radiation jeep survey, hydrogeochemical survey, ground radiometric survey, radon survey, exploratory drilling and mining, Exploration effort by the Atomic Minerals Directorate for Exploration and Research (AMD) has helped in identifying numerous uranium occurrences spread over the entire Siwalik belt between Poonch (Jammu and Kashmir) in the west and Tanakpur (Uttar Pradesh) in the east, in the northwest Himalaya. Eight significant zones were delineated, mostly confining to distinct stratigraphic horizons of the transition zone between Middle and Upper Siwaliks, and occasionally the transition zone between Lower and Middle Siwaliks. These mineralised zones have a considerable lateral extent of up to 12 km and are associated with sandstones and rarely conglomerates. Uranium mineralisation occurs in the form of peneconcordant lensoidal bodies with individual lenses traceable from a few tens of metres to 700m, sub-parallel to strike or dip, with average grades varying from 0.020 - 0.060% U 3 O 8 and thickness less than a metre to 4m. The host rock of uranium mineralisation is predominantly sandstone containing carbonaceous matter, pyrite and clay pellets. The sandstone is often arkosic and micaceous, and termed as lithic wacke and arkosic wacke. The uranium minerals present are uraninite, pitchblende, coffinite and secondary minerals such as tyuyamunite, metatyuyamunite, uranophane, bayleyite, andersonite, schoepite, liebegite, swartzite, schroekingerite, wulfenite, billictite, betauranophane, autunite and torbernite. Relatively higher concentrations or Se, Mo, Cu, Co, V and Au have been noted in a few uranirerous zones. Concentration or uranium in the Siwalik clastic sediments is controlled by the redox interface

  5. Bacterial biodiversity analysis of a contaminated soil from the Chernobyl exclusion zone and characterization of the committed interaction of a Microbacterium strain with uranium

    International Nuclear Information System (INIS)

    Theodorakopoulos, Nicolas

    2013-01-01

    characterization of the interactions between the selected bacteria isolate (Microbacterium) and U(VI) highlighted an active mechanism of detoxification which involves an efflux of the U(VI) entering the cell and an intracellular precipitation of U(VI) in form of autunite. (author) [fr

  6. Evidence for Multiple Modes of Uranium Immobilization by an Anaerobic Bacterium

    International Nuclear Information System (INIS)

    Ray, Allison; Bargar, John R.; Sivaswamy, Vaideeswaran; Dohnalkova, Alice; Fujita, Yoshiko; Peyton, Brent M.; Magnuson, Timothy S.

    2011-01-01

    Microbial reduction of hexavalent uranium has been studied widely for its potential role in bioremediation and immobilization of soluble U(VI) in contaminated groundwater. More recently, some microorganisms have been examined for their role in immobilization of U(VI) via precipitation of uranyl phosphate minerals mediated by microbial phosphate release, alleviating the requirement for long-term redox control. Here, we investigated the mechanism of U(VI) removal mediated by an environmental isolate, strain UFO1, that is indigenous to the Field Research Center (FRC) in Oak Ridge, TN and has been detected in U(VI)-contaminated sediments. Changes in U(VI) speciation were examined in the presence and absence of the electron-shuttling moiety, anthraquinone-2,6-disulfonate (AQDS). Cell suspensions were capable of nearly complete removal of 100 (micro)M U(VI) from solution within 48 hours; U(VI) removal was not dependent on the presence of an exogenous electron donor or AQDS, although AQDS increased the rate of U(VI) removal. X-ray Absorption Near Edge Structure (XANES) spectroscopic measurements indicated that U(IV) was the predominant oxidation state of uranium in cell suspensions in both the absence and presence of 100 (micro)M AQDS. However, extended X-ray Absorption Fine Structure spectroscopy (EXAFS) measurements indicated that 17% of the cell-associated precipitates in a U(VI)-treated suspension that lacked AQDS had spectral characteristics consistent with a uranyl phosphate solid phase. The potential involvement of phosphate was consistent with observed increases in soluble phosphate concentrations over time in UFO1 cell suspensions, which suggested phosphate liberation from the cells. TEM-EDS confirmed the presence of uranyl phosphate with a U:P ratio consistent with autunite (1:1). EXAFS analyses further showed that U(IV) was present predominantly as a monomeric complex sorbed to carboxylate functional groups on biomass and also suggested that a fraction of the U

  7. VEIN-TYPE URANIUM MINERALIZATION IN THE EASTERN DESERT OF EGYPT

    Directory of Open Access Journals (Sweden)

    M. M. Ghoneim

    2018-03-01

    Full Text Available Vein type uranium deposits where uranium minerals fill cavities veins, fractures, fissures, pore spaces, shear zone, breccia and stockworks in igneous, meta-sediments and metamorphic rocks are common source of uranium mineralization all over the wold. In Egypt, El-Erediya, El-Missikat and El Sela uranium mineralization occur in younger granite plutons in the Eastern Desert of Egypt. These plutons are considered as good examples of intra-granitic vein-type uranium mineralization. The goal of this review article is to study the characteristics of granites and Th-U vein mineralization El Sela area. Main tasks are characteristics of vein type uranium mineralization in the world and Egypt, characteristics of ore-bearing intrusive rocks in the El Sela area, mineralogy of Th-U vein-type mineralization in El Sela area and secondary U and Th minerals in granites. Results. The article revealed that El Sela granite is a peraluminous, high-K Calc-Alkaline (HKCA granite. Two-mica leucogranitic pluton is considered the source rock of U-mineralization at El-Sela area, while the altered microgranite and dolerite dikes are good traps for these mineralizations. The reactivated faults system trending ENE-WSW and NNW-SSE make favorable condition to form uranium mineralization associated with polymetallic mineralization that are redeposited in the two mica granite, microgranite and dolerite dikes. The metallic mineral assemblages in the veins mainly consist of pyrite, chalcopyrite, galena, sphalerite and fluorite that are associated with primary (uraninite, coffinite and secondary U-mineralization (uranophane and autunite that occur either as disseminated clusters or as microfracture filling and coating joint surface. Five types of thorite-group minerals can be distinguished: thorite, Zr-rich thorite, phosphothorite, uranothorite and Zr-rich uranothorite. ThO2 content of uraninite vary from (1.1 to 3 wt.%, for PbO contents from 1.16 to 2.35 wt.%, P2O5 contents from

  8. Long-term performance of elemental iron and hydroxyapatite for uranium retention in permeable reactive barriers used for groundwater remediation

    International Nuclear Information System (INIS)

    Biermann, V.

    2007-01-01

    Elemental iron (Fe 0 ) and hydroxyapatite (HAP) were evaluated as reactive mate-rials for use in permeable reactive barriers (PRBs) to remove uranium from conta-minated groundwater. Special attention was given to the long-term performance of the materials, which was investigated by means of column tests with a duration of up to 30 months using two different artificial groundwaters (AGW) with varying composition and uranium concentration. The interaction of the materials with AGW was studied in column tests using 237 U as a radiotracer to monitor the movement of the contamination front through the columns. The tested materials were shredded cast iron (granulated grey cast iron, 0.3 - 1.3 mm) supplied by Gotthard Mayer, Rheinfelden, Germany, and food quality grade hydroxyapatite (Ca 5 (PO 4 ) 3 OH, 99 % 0 (AGW with 9.6 mg U/L and low bicarbonate content of 120 mg/L). No breakthrough was observed for the Fe 0 columns with effluent uranium con-centrations being below the detection limit of 10 μg/L after treating more than 2,000 pore volumes (PV) and no uranium could be leached from loaded Fe 0 columns with 200 PV of uranium free AGW. However, columns with high Fe 0 content (≥ 50%) suffered from severe loss of permeability when AGW with ≥ 320 mg/L bicarbonate was used. In the HAP columns a breakthrough occurred with effluent uranium concentrations > 15 μg/l after treating 1,240 PV (10% and 50% breakthrough after 1,460 PV and 2,140 PV respectively). 12.2% of the accu-mulated uranium could be desorbed again with 840 PV of uranium free AGW. Adsorption was found to be the dominant reaction mechanism for uranium and HAP. Image analysis of high uranium content samples showed uranium and phosphate bearing crystals growing from HAP surfaces. The uranium phases chernikovite and meta-ankoleite of the autunite group were identified by x-ray diffraction. The existence of these mineral phases proves that surface precipitation also occurs under favourable conditions. No uranium

  9. Long-term performance of elemental iron and hydroxyapatite for uranium retention in permeable reactive barriers used for groundwater remediation; Langzeitverhalten von elementarem Eisen und Hydroxylapatit zur Uranrueckhaltung in permeablen reaktiven Waenden bei der Grundwassersanierung

    Energy Technology Data Exchange (ETDEWEB)

    Biermann, V.

    2007-11-21

    from HAP surfaces. The uranium phases chernikovite and meta-ankoleite of the autunite group were identified by x-ray diffraction. The existence of these mineral phases proves that surface precipitation also occurs under favourable conditions. No uranium mineral phases could be identified in spent Fe{sup 0} column material. But image analysis (ESEM / EDX) indicates formation of a mixed U(IV)/U(VI) oxide. While HAP long-term performance depends mainly on sorption capacity, maintaining hydraulic conductivity is crucial for Fe{sup 0}. In both cases water compositon has a great influence as well. (orig.)

  10. Study of the Reactions Controlling the Mobility of Uranium in Ground and Surface Water Systems in Contact with Apatite

    International Nuclear Information System (INIS)

    Taffet, M

    2004-01-01

    hydroxyapatite can sorb over 7.53 X 10 -6 moles or 1.8 mg of uranium in agreement with calculations based on phosphate and calcium oxide sites on the unit cell. Our work is significant because small masses of hydroxyapatite can sorb appreciable masses of uranium quickly over a wide range of chemistries. Preliminary work with ground water containing 260 ppb of uranium and cow bone char indicates that its sorptive capacity is appreciable less than pure hydroxyapatite. Pure crystalline hydroxyapatite sequestered 2.9 mg of uranium per m 2 as opposed to 0.083 mg of uranium sequestered per m 2 of cow bone char, or 27% versus 3.5% by surface area, respectively. Extended x-ray adsorption fine structure (EXAFS) spectroscopy defined mono- and bidentate sorption of uranium to phosphate and calcium oxide groups on the hydroxyapatite surface. The EXAFS data indicate that up to several thousand parts U per million parts hydroxyapatite, surface complexation, and not precipitation, is the predominant process. Above this uranium: hydroxyapatite mass ratio, precipitation of meta-autunite (H 2 (UO 2 )2(PO 4 ) 2 x 10H 2 0) dominates the sequestration process

  11. Spatial distribution of environmental risk associated to a uranium abandoned mine (Central Portugal)

    Science.gov (United States)

    Antunes, I. M.; Ribeiro, A. F.

    2012-04-01

    The abandoned uranium mine of Canto do Lagar is located at Arcozelo da Serra, central Portugal. The mine was exploited in an open pit and produced about 12430Kg of uranium oxide (U3O8), between 1987 and 1988. The dominant geological unit is the porphyritic coarse-grained two-mica granite, with biotite>muscovite. The uranium deposit consists of two gaps crushing, parallel to the coarse-grained porphyritic granite, with average direction N30°E, silicified, sericitized and reddish jasperized, with a width of approximately 10 meters. These gaps are accompanied by two thin veins of white quartz, 70°-80° WNW, ferruginous and jasperized with chalcedony, red jasper and opal. These veins are about 6 meters away from each other. They contain secondary U-phosphates phases such as autunite and torbernite. Rejected materials (1000000ton) were deposited on two dumps and a lake was formed in the open pit. To assess the environmental risk of the abandoned uranium mine of Canto do Lagar, were collected and analysed 70 samples on stream sediments, soils and mine tailings materials. The relation between samples composition were tested using the Principal Components Analysis (PCA) (multivariate analysis) and spatial distribution using Kriging Indicator. The spatial distribution of stream sediments shows that the probability of expression for principal component 1 (explaining Y, Zr, Nb, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Hf, Th and U contents), decreases along SE-NW direction. This component is explained by the samples located inside mine influence. The probability of expression for principal component 2 (explaining Be, Na, Al, Si, P, K, Ca, Ti, Mn, Fe, Co, Ni, Cu, As, Rb, Sr, Mo, Cs, Ba, Tl and Bi contents), increases to middle stream line. This component is explained by the samples located outside mine influence. The spatial distribution of soils, shows that the probability of expression for principal component 1 (explaining Mg, P, Ca, Ge, Sr, Y, Zr, La, Ce, Pr

  12. Immobilization of uranium and neptunium by microorganisms in subsurface crystalline rock environments

    Energy Technology Data Exchange (ETDEWEB)

    Krawczyk-Baersch, Evelyn; Schmeide, Katja; Bok, Frank [Helmholtz-Zentrum Dresden-Rossendorf, Institute of Resource Ecology, P.O. Box 51 01 19, D-01314 Dresden (Germany); Pedersen, Karsten [Department of Civil and Environmental Engineering, Chalmers University of Technology, SE-412 96 Goeteborg (Sweden)

    2014-07-01

    In crystalline rock, the dominant transport medium for radionuclides is groundwater flowing through subsurface fractures. Since groundwater is containing microorganisms, fracture surfaces support biological growth of microbial communities, the so-called bio-films. The microbial diversity of these bio-films depends on the microbial consortia and the chemical composition of the fracture water. Subsurface bio-films have a significant effect on the adsorption capacity of host rock formations by forming a barrier between the rock surface and the groundwater. They can significantly affect subsurface biogeochemical interactions, leading to the immobilization and adsorption of radionuclides. Microbial studies were performed to evaluate the relevance of microbial processes for the immobilization of radionuclides in a deep crystalline repository for high-level radioactive waste. Studies were performed in Olkiluoto, in the rock characterization facility ONKALO in Finland, and in the Aespoe Hard Rock Laboratory (HRL) in Sweden. Massive 5-10-mm thick bio-films were observed in both sites attached to tunnel walls where groundwater was seeping from bedrock fractures. In experiments the effect of uranium on bio-films was studied on site in the ONKALO tunnel by adding UO{sub 2}(ClO{sub 4}){sub 2} with a final U-concentration of 1.0x10{sup -5} M to the fracture water in a self-constructed flow cell by using detached bio-film samples. bio-film specimens collected for transmission electron microscopy studies indicated that uranium in the bio-film was immobilized intracellularly in microorganisms as needle-shaped uranyl phosphate minerals, similar to meta-Autunite (Ca[UO{sub 2}]{sub 2}[PO{sub 4}]{sub 2}.10-12H{sub 2}O). In contrast, thermodynamic calculation of the theoretical predominant fields of uranium species and time-resolved laser fluorescence spectroscopy showed that the formation of aqueous uranium carbonate species Ca{sub 2}UO{sub 2}(CO{sub 3}){sub 3} and Mg{sub 2}UO{sub 2

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