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Author Khoury, H.N.; salameh, E.M.; Clark, I.D.
Title Mineralogy and origin of surficial uranium deposits hosted in travertine and calcrete from central Jordan Type Journal Article
Year 2014 Publication Applied Geochemistry Abbreviated Journal
Volume 43 Issue Pages 49-65
Keywords (up)
Abstract Secondary uranium encrustations are hosted in thick travertine and calcrete deposits of Pleistocene–Recent age in central Jordan. The central Jordan varicolored marble and travertine are equivalent to the active metamorphic area in Maqarin, north Jordan. More than 100 samples were collected from the outcrops of the varicolored marble, travertine, calcrete, and the yellow uranium encrustations. The secondary yellow encrustations are mainly composed of uranyl vanadate complexes. Tyuyamunite Ca(UO2)2V25+O8·3(H2O)–strelkinite Na2(UO2)2V2O8·6(H2O) solid solution series are the major components and their composition reflects changes in the Ca/Na ratio in solution. Potentially, new vanadium free calcium uranate phases (restricted to the varicolored marble) were identified with CaO:UO3 ratios different from the known mineral vorlanite (CaU6+)O4. Carbon and oxygen isotope data from calcite in the varicolored marble are characterized by Rayleigh-type enrichment in light isotopes associated with release of 13C and 18O enriched CO2 by high temperature decarbonation during combustion of the bituminous marl. Stable isotope results from uranium hosted travertine and calcrete varieties exhibit a wide range in isotopic values, between decarbonated and normal sedimentary carbonate rocks. The depleted δ13C and δ18O values in the travertine are related to the kinetic reaction of atmospheric CO2 with hyperalkaline Ca(OH)2 water. The gradual enrichment of δ13C and δ18O values in the calcrete towards equilibrium with the surrounding environment is related to continuous evaporation during seasonal dry periods. Uranium mineralization in central Jordan resulted from the interplay of tectonic, climatic, hydrologic, and depositional events. The large distribution of surficial uranium occurrences hosted in travertine and calcrete deposits is related to the artesian ascending groundwater that formed extensive lakes along NNW–SSE trending depressions. Fresh groundwater moved upward through the highly fractured phosphate, bituminous marl and varicolored marble to form unusual highly alkaline water (hydroxide–sulfate type) enriched with sensitive redox elements among which were U and V.
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ISSN 0883-2927 ISBN Medium
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Call Number THL @ christoph.kuells @ khoury_mineralogy_2014 Serial 121
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Author Ingham, E.S.; Cook, N.J.; Cliff, J.; Ciobanu, C.L.; Huddleston, A.
Title A combined chemical, isotopic and microstructural study of pyrite from roll-front uranium deposits, Lake Eyre Basin, South Australia Type Journal Article
Year 2014 Publication Geochimica et Cosmochimica Acta Abbreviated Journal
Volume 125 Issue Pages 440-465
Keywords (up)
Abstract The common sulfide mineral pyrite is abundant throughout sedimentary uranium systems at Pepegoona, Pepegoona West and Pannikan, Lake Eyre Basin, South Australia. Combined chemical, isotopic and microstructural analysis of pyrite indicates variation in fluid composition, sulfur source and precipitation conditions during a protracted mineralization event. The results show the significant role played by pyrite as a metal scavenger and monitor of fluid changes in low-temperature hydrothermal systems. In-situ micrometer-scale sulfur isotope analyses of pyrite demonstrated broad-scale isotopic heterogeneity (δ34S=−43.9 to +32.4‰VCDT), indicative of complex, multi-faceted pyrite evolution, and sulfur derived from more than a single source. Preserved textures support this assertion and indicate a genetic model involving more than one phase of pyrite formation. Authigenic pyrite underwent prolonged evolution and recrystallization, evidenced by a genetic relationship between archetypal framboidal aggregates and pyrite euhedra. Secondary hydrothermal pyrite commonly displays hyper-enrichment of several trace elements (Mn, Co, Ni, As, Se, Mo, Sb, W and Tl) in ore-bearing horizons. Hydrothermal fluids of magmatic and meteoric origins supplied metals to the system but the geochemical signature of pyrite suggests a dominantly granitic source and also the influence of mafic rock types. Irregular variation in δ34S, coupled with oscillatory trace element zonation in secondary pyrite, is interpreted in terms of continuous variations in fluid composition and cycles of diagenetic recrystallization. A late-stage oxidizing fluid may have mobilized selenium from pre-existing pyrite. Subsequent restoration of reduced conditions within the aquifer caused ongoing pyrite re-crystallization and precipitation of selenium as native selenium. These results provide the first qualitative constraints on the formation mechanisms of the uranium deposits at Beverley North. Insights into depositional conditions and sources of both sulfide and uranium mineralization and an improved understanding of pyrite geochemistry can also underpin an effective vector for uranium exploration at Beverley North and other sedimentary systems of the Lake Eyre Basin, as well as in comparable geological environments elsewhere.
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ISSN 0016-7037 ISBN Medium
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Call Number THL @ christoph.kuells @ ingham_combined_2014 Serial 188
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Author Hamutoko, J.; Mapani, B.; Ellmies, R.; Bittner, A.; Külls, C.
Title A fingerprinting method for the identification of uranium sources in alluvial aquifers: An example from the Khan and Swakop Rivers, Namibia Type Journal Article
Year 2014 Publication Physics and Chemistry of the Earth, Parts A/B/C Abbreviated Journal
Volume 72 Issue Pages 34-42
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Publisher Pergamon Place of Publication Editor
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Call Number THL @ christoph.kuells @ Hamutoko2014fingerprinting Serial 19
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Author Müller, M.; Alaoui, A.; Külls, C.; Leistert, H.; Meusburger, K.; Stumpp, C.; Weiler, M.; Alewell, C.
Title Tracking water pathways in steep hillslopes by δ18O depth profiles of soil water Type Journal Article
Year 2014 Publication Journal of hydrology Abbreviated Journal
Volume 519 Issue Pages 340-352
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Publisher Elsevier Place of Publication Editor
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Call Number THL @ christoph.kuells @ Mueller2014tracking Serial 20
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Author Gaj, M.; Beyer, M.; Hamutoko, J.; Uugulu, S.; Wanke, H.; Koeniger, P.; Külls, C.; Lohe, C.; Himmelsbach, T.
Title How do soil types affect stable isotope ratios of 2H and 18O under evaporation: A Fingerprint of the Niipele subbasin of the Cuvelai-Etosha basin, Namibia Type Conference Article
Year 2014 Publication EGU Geophysical Abstracts Abbreviated Journal
Volume Issue Pages 5890
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Call Number THL @ christoph.kuells @ Gaj2014soil Serial 44
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Author Joseph, J.; Külls, C.
Title Calibration of 13C and 18O measurements in CO2 using Off-axis Integrated Cavity Output Spectrometer (ICOS) Type Conference Article
Year 2014 Publication EGU Geophysical Abstracts Abbreviated Journal
Volume Issue Pages 659
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Call Number THL @ christoph.kuells @ Joseph2014calibration Serial 45
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Author Külls, C.; Nunes, A.; Köbel-Batista, M.; Branquinho, C.; Bianconi, N.; Costantini, E.
Title Integrated use of soil physical and water isotope methods for ecohydrological characterization of desertified areas Type Conference Article
Year 2014 Publication EGU Geophysical Abstracts Abbreviated Journal
Volume Issue Pages 15430
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Call Number THL @ christoph.kuells @ Kuells2014integrated Serial 46
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Author Külls, C.
Title Ecohydrological principles in economic models of water resources in drylands and desert restoration Type Miscellaneous
Year 2014 Publication UNCCD, 2nd Scient. Conf. Abbreviated Journal
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Call Number THL @ christoph.kuells @ Kuells2014ecohydrological Serial 68
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Author Pastukhov, A.M.; Rychkov, V.N.; Smirnov, A.L.; Skripchenko, S.Y.; Poponin, N.A.
Title Purification of in situ leaching solution for uranium mining by removing solids from suspension Type Journal Article
Year 2014 Publication Minerals Engineering Abbreviated Journal
Volume 55 Issue Pages 1-4
Keywords (up) Bag filter, Firm particles, In situ leaching mining, Injection wells, Intake capacity, Purification
Abstract This study investigated the process of in situ leaching (ISL) method of uranium mining, and the removal of solid particles from the leaching solution. Investigations were carried out for 4months. The content of firm suspensions in the productive solutions arriving from the well field was up to standard of 3–5mg/l. After keeping in a settler of productive solutions within one hour concentration of suspensions decreases to 2–2.5mg/l. To increase the life of the wells requires more fine purification of the ISL solutions. The best results can be obtained but using filtration. Bag filters were used in experiments carried out at the extraction site. All samples of polypropylene bag filter was produced by the Tamfelt Corporation. The best results were obtained for fabrics S-51M03-L2K4 (pore size 3μm). After three month of trials following indicators of wells work were fixed: on the trial cell decrease in intake capacity did not occur; on the other cells of well field injectability of holes for the same period of time decreased for 15–40%. The results illustrated the high efficiency of this method, which allows injection wells to reach a constant intake capacity, making it possible for technological cells to achieve a constant productivity and balance. Purification of solutions allows to reduce acidulation term of new technological cells from 3–4 to 1.5–2months.
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ISSN 0892-6875 ISBN Medium
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Notes Approved no
Call Number THL @ christoph.kuells @ pastukhov_purification_2014 Serial 204
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Author Tan, K.; Li, C.; Liu, J.; Qu, H.; Xia, L.; Hu, Y.; Li, Y.
Title A novel method using a complex surfactant for in-situ leaching of low permeable sandstone uranium deposits Type Journal Article
Year 2014 Publication Hydrometallurgy Abbreviated Journal
Volume 150 Issue Pages 99-106
Keywords (up) Complex surfactant, In-situ leaching of uranium mining, Leaching kinetics, Low permeable sandstone uranium deposit, Resin adsorption and elution
Abstract Applications of a complex surfactant developed in-house to in-situ leaching of low permeable sandstone uranium deposits are described based on results from agitation leaching, column leaching, resin adsorption, and elution experiments using uranium containing solution from the in-situ leaching site. The results of agitation leaching experiments show that adding surfactant with different concentrations into leaching solution improves the leaching rate of uranium. The maximum leaching rate of uranium from agitation leaching reached 92.6% at an added surfactant concentration of 10mg/l. Result of column leaching experiment shows that adding surfactant with varying concentrations into leaching solutions increased the permeability coefficient of ore-bearing layer by 42.7–86.8%. The leaching rate of uranium from column leaching increased by 58.0% and reached 85.8%. The result of kinetic analysis shows that for the extraction of uranium controlled by diffusion without surfactant the apparent rate constant 0.0023/d changed to 0.0077/d for the extraction with surfactant controlled by both diffusion and surface chemical reactions. Results from resin adsorption and elution experiments show that there was no influence on resin adsorption and elution of uranium with an addition of 50mg/l surfactant to production solution from in-situ leaching. The adsorption curve, sorption capacity of resin, recycling of resin remained the same as without adding any surfactant. Introducing complex surfactant to leaching solution increased the peak concentration of uranium in eluents, reduced the residual uranium content in resin, and promoted the elution efficiency. The method of using a complex surfactant for in-situ leaching is useful for low permeable sandstone uranium deposits.
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ISSN 0304-386x ISBN Medium
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Call Number THL @ christoph.kuells @ tan_novel_2014 Serial 201
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