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Sample records for carnotite

  1. Correlation and origin of carnotite occurrences in the southern Nevada region

    International Nuclear Information System (INIS)

    Carnotite [K2(UO2)2(VO4)2.3H2O] is recognized at seven localities in the southern Nevada region. These general areas of occurrence are the Jean-Sloan Calcrete, Hidden Valley Calcrete, Hualapai Limestone, Boulder City ''fossil water table'', Horse Spring Formation type locality, Mormon Mesa Caliche, and exposures of the Willow Tank thrust fault. The carnotite occurrences pre-date the 3.80 MY (million years before present) basalt at Sandy Pint, post-date an 8.66 MY tuff that underlies the Hualapai Limestone, and are approximately coeval with the 5.84 MY Fortification Basalt. Analysis of the Th/U ratios from 2045 dry stream sediment samples collected during the National Uranium Resource Evaluation (NURE) Program indicates uranium depletion in Precambrian terrain of the region and enrichment in areas where carnotite is observed. Anomalous vanadium in dry stream sediment samples is associated with intermediate and mafic Cenozoic volcanic rocks of pre-Colorado River age, and to a lesser extent with uratic Precambrian rocks. Correlation of the Jean-Sloan Calcrete, Hidden Valley Calcrete, Mormon Mesa Caliche, Hualapai Limestone, and Boulder City ''fossil water table'' is proposed based on elevation, relief, and inferred common age and origin. Carnotite studies have provided recognition criteria for facies of a regional geomorphic surface that formed in association with sluggish shallow groundwater flow in axial drainage systems in the Late Miocene. Carnotite and gypsum were deposited in disrupted by normal faulting and climatic conditions become increasingly arid 5-6 MY ago. Major geologic events that approximately coincide with the formation of the carnotite occurrences include the Messinian Crisis, opening of the Gulf of California, and uplift of the Sierra Nevada

  2. Synthesis of potassium and calcium uranium vanadates, analogues of Carnotite and meta tyuyamunite minerals

    International Nuclear Information System (INIS)

    The aim of this study was to develop a synthesis of meta tyuyamunite (Ca(VUO6)2·3-5H2O) and carnotite (KVUO6·1-3H2O) under hydrothermal conditions. Also, crystals obtained from this synthesis were compared with crystals from melting method. The analyses of synthesis products were performed by X-ray techniques. X-ray diffraction was used for both species identification, whereas scanning electron microscopy was used to analyze their morphology and elemental composition. Both uranium vanadates were positive synthesized under hydrothermal conditions, besides, their morphology presents particles agglomerates. Calcium uranium vanadate agglomerates contain well-defined crystals, whereas potassium uranium vanadate agglomerates consist in fine powder particles. (Author)

  3. Synthesis of potassium and calcium uranium vanadates, analogues of Carnotite and meta tyuyamunite minerals

    Energy Technology Data Exchange (ETDEWEB)

    Requena Y, J. L.; Reyes C, M.; Torres M, E.; Lardizabal, D.; Montero C, M. E. [Centro de Investigacion en Materiales Avanzados, S. C., Miguel de Cervantes No. 120, Complejo Industrial Chihuahua, 31109 Chihuahua (Mexico); Riveros, H., E-mail: elena.montero@cimav.edu.mx [UNAM, Instituto de Fisica, Circuito Exterior, Ciudad Universitaria, 04510 Mexico D. F. (Mexico)

    2012-06-15

    The aim of this study was to develop a synthesis of meta tyuyamunite (Ca(VUO{sub 6}){sub 2}{center_dot}3-5H{sub 2}O) and carnotite (KVUO{sub 6}{center_dot}1-3H{sub 2}O) under hydrothermal conditions. Also, crystals obtained from this synthesis were compared with crystals from melting method. The analyses of synthesis products were performed by X-ray techniques. X-ray diffraction was used for both species identification, whereas scanning electron microscopy was used to analyze their morphology and elemental composition. Both uranium vanadates were positive synthesized under hydrothermal conditions, besides, their morphology presents particles agglomerates. Calcium uranium vanadate agglomerates contain well-defined crystals, whereas potassium uranium vanadate agglomerates consist in fine powder particles. (Author)

  4. Leaching Characteristics of Uranium and Vanadium From Wadi El-Sahu Carnotite- Bearing Kaolin, South Western Sinai, Egypt

    International Nuclear Information System (INIS)

    The leaching roats of carnotite-bearing kaolin sample from the lower carboneferous Um Bogma formation at Wadi El-Sahu, south western Sinai, Egypt, contain 2.6% U3O8 and 1.2% V2O5 , have been studied. Both sulfuric acid agitation and pug leaching techniques were applied. From the obtained agitation results, it was concluded that both acid concentration and temperature were quite important for increasing the leaching efficiency of the two studied metal values; about 82.5 and 50.5 % for U and V, respectively. The optimum conditions were 200 g/l H2SO4 at 50 degree C for 2 h agitation time in a solid / liquid ratio of 1/5. the results showed that high temperature and concentrated acid were required and the applied optimum pug leaching conditions of mesh size < 200 with an ore / acid ratio of 1/1 at 300 degree C for 4 h have resulted in about 81 and 87% of U and V leaching efficiencies, respectively.

  5. Pulmonary function evaluations of dogs exposed to uranium ore dust

    International Nuclear Information System (INIS)

    Pulmonary function evaluations were conducted on dogs exposed to carnotite uranium ore dust. Significant changes were detected in the slope of the single-breath N2 washout curve, suggesting an uneven distribution of ventilation

  6. Hydrology of uranium deposits in calcretes of western Australia

    International Nuclear Information System (INIS)

    Carnotite is the principal uranium mineral occurring in the calcreted trunk valleys of the ancient drainage system which extends over 400,000 sq km of south-western Australia. The calcretes, accumulations of calcium and magnesium carbonates up to 100 km long, 5 km wide, and 20 m thick, are discontinuous in character but act as aquifers for groundwaters of relatively low salinity that flow sluggishly to playa lakes. Catchment basins draining large areas of Precambrian granitic rocks can yield up to 200 parts per billion of uranium in the oxidizing environment of the water at shallow depth near the base of the calcretes. Where the product of the concentrations of active ion species of uranium, vanadium, and potassium exceeds the solubility product of carnotite, this mineral precipitates in fissures or between the carbonate and clay particles. Vanadium appears to be generally deficient in the upper levels of the aquifers; however, where it has been supplied at the required concentration from deeper reduced waters, forced up, for example, by a bar of resistant bedrock, carnotite mineralization has occurred. The incongruent dissolution of carnotite liberates vanadium preferentially. Some carnotite deposits currently are being leached and redeposited downstream. Where calcrete channels reach salt lakes, great increases in the activity of calcium and potassium promote further carnotite deposition by the decomplexing of uranyl carbonate complexes carried down the aquifers. Many areas of carnotite mineralization are now known. The largest, at Yeelirre, contains 46,000 MT of U3O8 at an average grade of 0.15%. Extraction from the ore is hampered by the carbonate content and the presence of illite-montmorillonite clay phases, but alkaline leach techniques are practicable. An appreciable proportion of the carnotite, in an extremely fine-grained form, can be associated with the clay fraction

  7. The occurrence of plutonium in nature

    Energy Technology Data Exchange (ETDEWEB)

    Levine, Charles A.; Seaborg, Glenn T.

    1950-11-29

    Plutonium has been chemically separated from seven different ores and the ratios of plutonium to uranium determined. This ratio was found to be fairly constant in pitchblende and monazite ores, in which the uranium content varied from 50% t o 0.24%, and substantially less in carnotite and fergusonite.

  8. Energy transfer processes in Ca.sub.3./sub.Tb.sub.2-x./sub.Eu.sub.x./sub.Si.sub.3./sub.O.sub.12./sub. (x = 0–2)

    Czech Academy of Sciences Publication Activity Database

    Carrasco, I.; Bartosiewicz, Karol; Nikl, Martin; Piccinelli, F.; Bettinelli, M.

    2015-01-01

    Roč. 48, Oct (2015), s. 252-257. ISSN 0925-3467 EU Projects: European Commission(XE) 316906 - LUMINET Institutional support: RVO:68378271 Keywords : phosphors * silico-carnotite * luminescence * energy transfer Subject RIV: BH - Optics, Masers, Lasers Impact factor: 1.981, year: 2014

  9. Uranium occurence in nature: Geophysical prospecting, and its occurence in Syria

    International Nuclear Information System (INIS)

    A general idea about naturaly occured uranium minerals such as uranite, pechblende, carnotite, coffinit, and bronnerit is given. At the same time, different geophysical methods and detecting devices applied for uranium exploration have been demonstrated. Investigations and studies carried out in Syria point to a uranium content of 100 ppm in the exploited Syrian phosphorite. 1 fig., 1 tab

  10. An assessment of the use of hydrogeochemistry in exploration for calcrete uranium in Australia

    International Nuclear Information System (INIS)

    The role of hydrogeochemistry in exploration for calcrete uranium deposits in Australia is reviewed and the sampling and analytical procedures used are described. The concept of carnotite solubility index (CSI) is introduced and a simplified derivation is given for field use. The various interpretation schemes are reviewed and compared. On the basis of experience in Australia, the uranium content of the aquifer was found to provide a guide to the fertility of the system, and anomalous vanadium concentrations in the groundwater could be related to carnotite mineralization. Using the simplified CSI function, values of -3 to zero and upwards were found to be indicative of prospective drainages. It is concluded that water sampling surveys carried out in conjunction with shallow drilling programs make for the most efficient use of hydrogeochemistry in calcrete exploration

  11. Possible variations on the calcrete-gypcrete uranium model

    International Nuclear Information System (INIS)

    Genetic models and favorability criteria for calcrete and gypcrete uranium deposits based upon Yeelirrie and other occurrences in Western Australia and upon Langer Henirich and others in Namibia-South West Africa are summarized. Viable analogues of these world-class deposits have not yet been found in USA even though several of the favorable conditions occur in the southwest. A principal deterrent to economic concentration has been tectonic instability. But even in the most favorable areas it is not clear that climates have ever been sufficiently similar to that of the valley-calcrete region of Western Australia. Extensive, thick valley (nonpedogenic) calcretes such as those which host the carnotite in Australia and in Namibia have not been documented here. Nevertheless, submarginal occurrances of carnotite have been found in southwestern United States in small bodies of nonpedogenic and mixed pedogenic-nonpedogenic calcrete. Much of the study is based upon occurrences of carnotite-bearing calcrete and calcrete-gypcrete in the Republic of South Africa. Several of these are described briefly. Some reference is also made to new occurrences and to new data on previously described occurrences on the Namib Desert. Possible variations on the Western Australian and Namibia-South West Africa models which are considered are capillary rise of U in solution, addition of new uraniferous sediment over a calcrete, lateral access of U into a pedogenic calcrete, reworking of U from a weekly mineralized pedogenic calcrete or gypcrete into a new or reconstituted calcrete, or into an unrelated environment for fixation of U

  12. Crystal structure refinements of two francevillites, (Ba,Pb)[(UO2)2V2O8].5H2O

    International Nuclear Information System (INIS)

    The crystal structures of two francevillites with atomar Ba/Pb ratios of 0.96/0.04 and 0.69/0.31 have been refined from X-ray four-circle diffractometer data to R-values of 0.025 and 0.027, respectively. Existing structure data were considerably improved. A previously missing water molecule was found as part of (Ba,Pb)O4(H2O)5 polyhedra which link adjacent [(UO2)2V2O8] layers. Aspects concerning the conformation of these layers in francevillite and other representatives of the carnotite-tyuyamunite group are briefly discussed. (orig.)

  13. Multielement drainage reconnaissance of the AD DAWW region, central Syria

    International Nuclear Information System (INIS)

    Geochemical drainage reconnaissance has been used to investigate the dispersion of uranium and its associated elements in the arid Ad Daww region of central Syria. Low order anomalies of U, accompanied by various combinations of anomalous concentrations of As, Ba, Mo, Se, Sr and V, have been recognized in wadi sediments and groundwaters. In wadi sediments anomalous dispersion trains are short and reflect phosphate rock units and minor occurrences of carnotite and tyuyamunite. Hydrogeochemical anomalies are found mainly in an aquifer in coarse clastic Neogene sediments. These anomalies constitute multielement geochemical signatures similar to those associated with sedimentary uranium deposits. 26 refs. (Author)

  14. Sandstone-type uranium deposits

    International Nuclear Information System (INIS)

    Sandstone deposits represent a large part of the world's uranium deposits, and are particularly common in the United States of America. Orebodies of this type tend to exhibit many of the following features: (1) tabular or roll shape; (2) cross-bedded grey or green sandstone host rock, generally of Silurian or younger age; (3) a certain minimum thickness of sandstone; (4) mudstone interbedded with the sandstone; and (5) abundant organic matter and pyrite. The orebodies contain mainly uraninite and coffinite, with carnotite and other secondary minerals, and are commonly clustered along mineral trends. (author)

  15. Distribution of calcretes and gypcretes in southwestern United States and their uranium favorability, based on a study of deposits in Western Australia and South West Africa (Namibia)

    International Nuclear Information System (INIS)

    Calcrete, dolocrete, and gypcrete carnotite are abundant in western Australia and Namib Desert, although only a few are of ore grade. The geology of these deposits are described. A genetic classification of calcretes emphasizing uranium favorability was developed, based on the distinction between pedogenic and nonpedogenic processes. Similarities between western Australia and South West Africa give support for the conclusions that lateral transport of U in groundwater is essential to ore deposition and that bedrock barriers or constrictions which narrow the channel of subsurface flow or force the water close to the land surface, greatly favor the formation of uraniferous calcretes. Criteria for uranium favorability deduced from the Australian and South West African studies were applied in a preliminary way to the southern Basin and Range Province of U.S. The procedure is to search for areas in which nonpedogenic calcrete or gypcrete may have developed. A caliche distribution map was compiled from soil survey and field data. Many areas were visited and some of the more interesting are described briefly, including parts of Clark County, Nevada, with occurrences of carnotite in calcrete

  16. Distribution of calcretes and gypcretes in southwestern United States and their uranium favorability, based on a study of deposits in Western Australia and South West Africa (Namibia)

    Energy Technology Data Exchange (ETDEWEB)

    Carlisle, D.; Merifield, P.M.; Orme, A.R.; Kohl, M.S.; Kolker, O.; Lunt, O.R.

    1978-01-06

    Calcrete, dolocrete, and gypcrete carnotite are abundant in western Australia and Namib Desert, although only a few are of ore grade. The geology of these deposits are described. A genetic classification of calcretes emphasizing uranium favorability was developed, based on the distinction between pedogenic and nonpedogenic processes. Similarities between western Australia and South West Africa give support for the conclusions that lateral transport of U in groundwater is essential to ore deposition and that bedrock barriers or constrictions which narrow the channel of subsurface flow or force the water close to the land surface, greatly favor the formation of uraniferous calcretes. Criteria for uranium favorability deduced from the Australian and South West African studies were applied in a preliminary way to the southern Basin and Range Province of U.S. The procedure is to search for areas in which nonpedogenic calcrete or gypcrete may have developed. A caliche distribution map was compiled from soil survey and field data. Many areas were visited and some of the more interesting are described briefly, including parts of Clark County, Nevada, with occurrences of carnotite in calcrete. (DLC)

  17. Recovery of uranium low grade ores by froth flotation: study of the texture and synergetic effects of flotation reagents

    International Nuclear Information System (INIS)

    Due to the energy growing demand, uranium low grade ores may be those exploited in the future. Uranium ores conventional treatment does not often use mineral processing such as concentration methods for reducing leaching reagent consumption. The aim of this work is to develop an upgrading process to improve the operating process (alkaline heap leaching) taking into account the mineralogical and textural variability of the ore. The Trekkopje deposit is composed of calcrete and a gypscrete. The uranium bearing mineral is carnotite (K2(UO2)2 [VO4]2.3H2O). The gangue minerals are composed by silicates, such as quartz, feldspars, micas and Ca-minerals, calcite and gypsum (XRD and ICP-MS analysis). A SEM image processing was used to study the textural properties and the exposed free surface of mineral inclusions in clay clusters. In calcrete milled to -200 μm, 50 % of all carnotite is associated with clay clusters, which are composed by 98 % of palygorskite, 2 % of illite, montmorillonite, and interbedded clays (XRD and microprobe analysis). The carnotite grain size is 95 % less than 70 μm. Calcite is the main inclusion in clay clusters. Indeed, the calcite inclusions average rate in the clay clusters is 12 % and 5 % for carnotite inclusion. And the free exposed surface percentage of these minerals in clay clusters is 3 % and 6 %, thus indicating that the inclusions should not affect the behavior of mixed clay particles. However, ore flotation essays did not verify this hypothesis. Three minerals separation have been proposed based on the mineral ability to consume leaching reagents: separating Ca-minerals from silicates, palygorskite from gangue minerals and carnotite from gangue minerals. A study of silicates and Ca-minerals electrokinetic properties (electrophoresis) was carried out to select the collectors and the optimum pH range for selective flotation. Basic pH near neutral was proved to be optimal for the separation of gangue minerals with cationic or anionic

  18. Design and construction of a system to determine Radon-222 through alpha spectroscopy; Diseno y construccion de un sistema para determinar Radon-222 mediante espectroscopia alfa

    Energy Technology Data Exchange (ETDEWEB)

    Bonifacio M, J. [Universidad Autonoma del Estado de Mexico. Facultad de Quimica. Toluca (Mexico)

    1991-12-31

    The purpose of this work consists in the design a radon-222 gas measurement system utilizing a surface barrier detector with the objective to obtain a more accurate measurement for this isotope through an alpha particle spectrum and so to address as to avoid the activity influence of the descendants of short half-life, which are too beta particles emitters, already other methods it must be correction series to obtain the real value of radon activity. Here are presented the general properties properties of radon, the experimental part description indicating the design to measure the radon-222 gas and its parts, as well as too the standard separation of radium-226 starting from carnotite mineral. Finally, it is presented the results obtained with a discussion about it. (Author) results obtained with a discussion about it. (Author)

  19. The Vanadium Window with special reference to Joseph and James Flannery's contribution to the American steel and radium industries

    International Nuclear Information System (INIS)

    The discovery of vanadium is described and the founding of the American Vanadium Company by Joseph Flannery (1867-1920) and its headquarters building in Pittsburgh in which was the stained glass window depicting the origin of the name Vanadium. Company orders for vanadium steel were obtained for the Panama canal and from Henry Ford. When his sister was diagnosed with cancer, Joseph Flannery withdrew from his vanadium interests and founded the Standard Chemical and Radium Chemical Companies which were the major suppliers of radium in the USA in the 1920s (before the Union Minicre du Haut Katanga commenced its commercial operations), processed from American mined carnotite in Colorado and Utah. Significant contributions to these enterprises involving vanadium and radium were also made by Joseph's elder brother, James Flannery (1848-1920). (author)

  20. Experiments by the Mexican NNEC on the Control of Airborne Radioactive Contamination

    International Nuclear Information System (INIS)

    The installations of the Mexican National Nuclear Energy Commission have to deal with the problem of environmental contamination caused by dust and aerosols suspended in the air and originating mainly with such uranium-bearing ores as tyuyamunite, carnotite, betafite, technical-grade sodium uranate, ammonium uranate concentrate, uranium tetrafluoride and uranium dioxide. To prevent environmental contamination by these radioactive materials, the Commission has experimented with three different systems, based on the principle of extracting the dust from the environment, passing it through a cyclone system, separating the particles of larger size and controlling the small particles or aerosols by means of filtration, dilution in liquid columns and dilution in liquid curtains. On the basis of the results obtained, plans have been made for supplementing the systems with an adsorption column and an ion exchange column, depending on the specific requirements of each laboratory. (author)

  1. Potentialities of in-situ leaching of uranium and copper ore material in west central Sinai, Egypt

    International Nuclear Information System (INIS)

    A low grade uranium-copper ore material is recently recorded in the Paleozoic sedimentary sequence in west central Sinai, Egypt. The host rocks composed mainly of siltstone, clay, sand and gravel. A number of secondary uranium and copper minerals have been reported including mainly uranophane, carnotite, meta-tyuyamunite and meta-autunite beside atacamite, para-atacamite and langite. Series of lab percolation leaching experiments in both vertical and horizontal columns have been performed using acid and alkaline leaching reagents. Due to the fact that the ore material is situated above the water table, the in-situ leaching technique is doubtful. However, other natural leaching methods especially heap and in place leaching could be proposed. (author). 23 refs, 12 figs, 4 tabs

  2. Analysis of stream sediment reconnaissance data for mineral resources from the Montrose NTMS Quadrangle, Colorado

    International Nuclear Information System (INIS)

    Multivariate statistical analysis to support the National Uranium Resource Evaluation and to evaluate strategic and other commercially important mineral resources was carried out on Hydrogeochemical and Stream Sediment Reconnaissance data from the Montrose quadrangle, Colorado. The analysis suggests that: (1) the southern Colorado Mineral Belt is an area favorable for uranium mineral occurrences; (2) carnotite-type occurrences are likely in the nose of the Gunnison Uplift; (3) uranium mineral occurrences may be present along the western and northern margins of the West Elk crater; (4) a base-metal mineralized area is associated with the Uncompahgre Uplift; and (5) uranium and base metals are associated in some areas, and both are often controlled by faults trending west-northwest and north

  3. Analysis of stream sediment reconnaissance data for mineral resources from the Montrose NTMS Quadrangle, Colorado

    Energy Technology Data Exchange (ETDEWEB)

    Beyth, M.; Broxton, D.; McInteer, C.; Averett, W.R.; Stablein, N.K.

    1980-06-01

    Multivariate statistical analysis to support the National Uranium Resource Evaluation and to evaluate strategic and other commercially important mineral resources was carried out on Hydrogeochemical and Stream Sediment Reconnaissance data from the Montrose quadrangle, Colorado. The analysis suggests that: (1) the southern Colorado Mineral Belt is an area favorable for uranium mineral occurrences; (2) carnotite-type occurrences are likely in the nose of the Gunnison Uplift; (3) uranium mineral occurrences may be present along the western and northern margins of the West Elk crater; (4) a base-metal mineralized area is associated with the Uncompahgre Uplift; and (5) uranium and base metals are associated in some areas, and both are often controlled by faults trending west-northwest and north.

  4. Design and construction of a system to determine Radon-222 through alpha spectroscopy

    International Nuclear Information System (INIS)

    The purpose of this work consists in the design a radon-222 gas measurement system utilizing a surface barrier detector with the objective to obtain a more accurate measurement for this isotope through an alpha particle spectrum and so to address as to avoid the activity influence of the descendants of short half-life, which are too beta particles emitters, already other methods it must be correction series to obtain the real value of radon activity. Here are presented the general properties properties of radon, the experimental part description indicating the design to measure the radon-222 gas and its parts, as well as too the standard separation of radium-226 starting from carnotite mineral. Finally, it is presented the results obtained with a discussion about it. (Author) results obtained with a discussion about it. (Author)

  5. Multivariate statistical analysis of stream sediments for mineral resources from the Craig NTMS Quadrangle, Colorado

    Energy Technology Data Exchange (ETDEWEB)

    Beyth, M.; McInteer, C.; Broxton, D.E.; Bolivar, S.L.; Luke, M.E.

    1980-06-01

    Multivariate statistical analyses were carried out on Hydrogeochemical and Stream Sediment Reconnaissance data from the Craig quadrangle, Colorado, to support the National Uranium Resource Evaluation and to evaluate strategic or other important commercial mineral resources. A few areas for favorable uranium mineralization are suggested for parts of the Wyoming Basin, Park Range, and Gore Range. Six potential source rocks for uranium are postulated based on factor score mapping. Vanadium in stream sediments is suggested as a pathfinder for carnotite-type mineralization. A probable northwest trend of lead-zinc-copper mineralization associated with Tertiary intrusions is suggested. A few locations are mapped where copper is associated with cobalt. Concentrations of placer sands containing rare earth elements, probably of commercial value, are indicated for parts of the Sand Wash Basin.

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

    International Nuclear Information System (INIS)

    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 Cu0.8(H3O)0.2(UO2)2(PO4)2.8H2O, meta-autunite Ca(UO2)2(PO4)2.6H2O, meta-ankoleite K2(UO2)2(PO4)2.6H2O and carnotite K2(UO2)2(VO4)2.3H2O 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 (PO43- or V2O86-) and uranyl form parallel layers between which counter cations (Cu2+, Ca2+ 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 solubility constants. Similarly, the dissolution of meta

  7. Multivariate statistical analysis of stream sediments for mineral resources from the Craig NTMS Quadrangle, Colorado

    International Nuclear Information System (INIS)

    Multivariate statistical analyses were carried out on Hydrogeochemical and Stream Sediment Reconnaissance data from the Craig quadrangle, Colorado, to support the National Uranium Resource Evaluation and to evaluate strategic or other important commercial mineral resources. A few areas for favorable uranium mineralization are suggested for parts of the Wyoming Basin, Park Range, and Gore Range. Six potential source rocks for uranium are postulated based on factor score mapping. Vanadium in stream sediments is suggested as a pathfinder for carnotite-type mineralization. A probable northwest trend of lead-zinc-copper mineralization associated with Tertiary intrusions is suggested. A few locations are mapped where copper is associated with cobalt. Concentrations of placer sands containing rare earth elements, probably of commercial value, are indicated for parts of the Sand Wash Basin

  8. Formerly utilized MED/AEC Sites Remedial Action Program. Radiological survey of the former VITRO Rare Metals Plant, Canonsburg, Pennsylvania. Final report

    International Nuclear Information System (INIS)

    This 18-acre site was used from 1911 to 1922 to extract radium from carnotite ore, from 1930 to 1942 to extract radium and uranium salts from onsite residues and carnotite ore, and from 1942 to 1957 to recover uranium from various ores and scrap materials. The radiological survey was conducted in two phases, Phase I included measurement of radon and radon daughter concentrations in onsite buildings; concentrations measured in this part of the survey were all above guideline levels. Phase II consisted of measurement of surface contamination levels on the site, external gamma radiation levels at 1 m above surfaces on and near the site, radionuclide concentrations in surface and subsurface soil and water on and near the site, and radon concentrations in air at offsite locations. The results of the second phase of the survey indicate that large quantities of the radioactive wastes generated during radium and uranium recovery operations still remain on the site. Radium-bearing wastes are present in soil beneath or adjacent to each of the buildings on the site and in the top few feet of soil over almost the entire site, with some areas being contaminated to a depth of 16 ft or more. Alpha contamination levels, beta--gamma dose rates, and external gamma radiation levels in some areas of the buildings and outdoors on the site are above current federal guidelines concerning the release of property for unrestricted use. Concentrations of 226Ra in water in holes drilled on the site are above the maximum permissible concentration (MPC/sub w/). Also, measurements made offsite show that contamination from the site has spread to nearby offsite locations, and that there is significant atmospheric transport of 222Rn from the site

  9. Formerly utilized MED/AEC sites remedial action program. Radiological survey of the former VITRO Rare Metals Plant, Canonsburg, Pennsylania

    International Nuclear Information System (INIS)

    The results of a radiological survey of the former Vitro Rare Metals Plant in Canonsburg, Pennsylvania, are presented in this report. This 18-acre site was used from 1911 to 1922 to extract radium from carnotite ore, from 1930 to 1942 to extract radium and uranium salts from onsite residues and carnotite ore, and from 1942 to 1957 to recover uranium from various ores and scrap materials. The radiological survey was conducted in two phases. Phase I included measurement of radon and radon daughter concentrations in onsite buildings; concentrations measured in this part of the survey were well above guideline levels. Phase II consisted of measurement of surface contamination levels on the site, external gamma radiation levels at 1 m above surfaces on and near the site, radionuclide concentrations in surface and subsurface soil and water on and near the site, and radon concentrations in air at offsite locations. The results of the second phase of the survey indicate that large quantities of the radioactive wastes generated during radium and uranium recovery operations still remain on the site. Radium-bearing wastes are present in soil beneath or adjacent to each of the buildings on the site and in the top few feet of soil over almost the entire site, with some areas being contaminatd to a depth of 16 ft or more. Alpha contamination levels, beta-gamma dose rates, and external gamma radiation levels in some areas of the buildings and outdoors on the site are above current federal guidelines concerning the release of property for unrestricted use. Concentrations of 226Ra in water in holes drilled on the site are above the maximum permissible concentration. Also, measurements made offsite show that contamination from the site has spread to nearby offsite locations, and that there is significant atmospheric transport of 222Rn from the site

  10. Biological effects of daily inhalation of radon and its short-lived daughters in experimental animals

    International Nuclear Information System (INIS)

    Syrian golden hamsters, C57BL mice, and specific-pathogen-free rats were exposed simultaneously in groups of 16 animals each for 90 hours per week to aerosols consisting of radon plus 3000--6000 Working Levels of radon-daughters with and without 18 mg/m3 carnotite uranium ore dust. Condensation nuclei concentrations ranged from 2000--4000 per ml and from 90,000--120,000 per ml in the chamber without and with uranium ore dust, respectively. At 4 months of exposure only one of the rodents remained alive. Histopathology of radon-daughter exposed mice includes acute interstitial pneumonitis, severe pulmonary congestion, and supperative rhinitis; mice inhaling radon-daughters with ore showed these lesions plus macrophage proliferation, alveolar septal cell hyperplasia, and bronchial epithelial hyperplasia. Hamsters inhaling radon-daughters showed proliferating lesions characterized by alveolar septal thickening, bronchiolar epithelial hyperplasia, septal fibrosis, and occasionally adenomatoid metaplasia and squamous metaplasia. Hamsters inhaling radon-daughters with ore dust showed similar effects plus granulomatous response and intense septal fibrosis. Rats inhaling radon-daughters showed lesions similar to those of hamsters but more focalized with classic radiation pneumonitis; rats exposed to radon-daughters with ore showed similar lesions, with greater consolidation and pneumoconiosis. These findings will be discussed in relation to pulmonary pathology in uranium miners

  11. A brief history of the American radium industry and its ties to the scientific community of its early Twentieth Century

    International Nuclear Information System (INIS)

    Federally funded remedial action projects are presently underway in New Jersey and Colorado at sites containing 226Ra and other radionuclides from radium-uranium ore extraction plants that operated during the early twentieth century. They are but the latest chapter in the story of an American industry that emerged and perished in the span of three decades. Major extraction plants were established in or near Denver (CO), Pittsburgh (PA), and New York City (NY) to process radium from ore that came largely from the carnotite deposits of western Colorado and eastern Utah. The staffs of these plants included some of the finest chemists and physicists in the nation, and the highly-refined radium products found a variety of uses in medicine and industry. The discovery of high-grade pitchblende ores in the Belgian Congo and the subsequent opening of an extraction plant near Antwerp, Belgium, in 1992, however, created an economic climate that put an end to the American radium industry. The geologic, chemical, and engineering information gathered during this era formed the basis of the uranium industry of the later part of the century, while the tailings and residues came to be viewed as environmental problems during the same period

  12. Histopathologic, morphometric, and physiologic investigation of lungs of dogs exposed to uranium-ore dust

    International Nuclear Information System (INIS)

    The most consistent pulmonary-function change attributed to carnotite uranium-ore-dust exposure (at 15 mg/m3, for 4 h/day, 5 days/week) is an increased slope of the single-breath N2 washout curve, suggesting an uneven distribution of ventilation. This change was observed in dogs exposed for less than 1 year and continued through 4 years of exposure. Measurements of pulmonary resistance, after 27, 40 and 47 months exposure, showed slight age-related changes and increasing differences between control and exposed animals with duration of exposure. These two changes are suggestive of a bronchitic response, similar to the industrial bronchitis of mine workers. The most notable pulmonary lesions observed in dogs exposed for up to 4 years are: vesicular emphysema, peribronchiolitis and focal pneumoconiosis. Lesions of the major airways and upper respiratory tract, when present, were minimal in severity. Pulmonary vesicular emphysema was present in all but one of the examined dogs. The emphysema was dose-related, in that it was present only to a slight degree in dogs exposed for less than 3 years and, thereafter, increased in severity. Morphometric measurement data confirmed the value of the histopathologic grading system for the degree of emphysema. These data correlated best with the dynamic pulmonary compliance measurements

  13. Geochemistry of uranium in ground waters of the Conlara river Valley, San Luis and Cordoba provinces (Argentina)

    International Nuclear Information System (INIS)

    Geochemical characteristics of ground waters related with lixiviation, transport and precipitation of uranium in the Conlara river valley (provinces of San Luis and Cordoba (Argentina)) are studied. Anions and cations' distributions, together with hardness, specific conductivity, pH, Eh, and uranium and vanadium contents, have been studied. Those parameters characterize four hidrogeochemical facies along an E-W profile: a calcic strong bicarbonate facies, an alkaline-calcic bicarbonate facies, an alkaline sulfate facies, and a strong alkaline sulfate facies. An ''Interphase zone'' (transition from bicarbonate water to sulfate water), where changes in composition may define a geochemical environment capable of UO2 precipitation, has been determined. The chemical-Thermodynamic studies give a dominance of UDC and UTC complexs ions (even in sulfate waters), so they represent the 99% of present ions. Besides, the calculated values required for equilibrium with uraninite or carnotite resulted much greater than those obtained in the performed experiments. It means that the precipitation of those minerals requires either the presence of greate amounts of uranium or vanadium, or a reducing environment with Eh values smaller than the observed ones. Finally, the steps to be taken in future investigations are suggested in view to a drilling plan where: 1) Priority to the ''Interphase zone'' areas is given. 2) The deepest aquifers in Tertiary sediments of the basin have to be reached in order to get the convenient environmental conditions (i.e. smallest Eh values) for uranium or uranium-vanadium precipitation. (author)

  14. Separation of Actinium 227 from the uranium minerals

    International Nuclear Information System (INIS)

    The purpose of this work was to separate Actinium 227, whose content is 18%, from the mineral carnotite found in Gomez Chihuahua mountain range in Mexico. The mineral before processing is is pre-concentrated and passed, first through anionic exchange resins, later the eluate obtained is passed through cationic resins. The resins were 20-50 MESH QOWEX and 100-200 MESH 50 X 8-20 in some cased 200-400 MESH AG 50W-X8, 1X8 in other cases. The eluates from the ionic exchange were electrodeposited on stainless steel polished disc cathode and platinum electrode as anode; under a current ODF 10mA for 2.5 to 5 hours and of 100mA for .5 of an hour. it was possible to identify the Actinium 227 by means of its descendents, TH-227 and RA-223, through alpha spectroscopy. Due to the radiochemical purity which the electro deposits were obtained the Actinium 227 was low and was not quantitatively determined. A large majority of the members of the natural radioactive series 3 were identified and even alpha energies reported in the literature with very low percentages of non-identified emissions were observed. We conclude that a more precise study is needed concerning ionic exchange and electrodeposit to obtain an Actinium 227 of radiochemical purity. (Author)

  15. Design and construction of a system to analyze Radon 222 by means of alpha spectroscopy

    International Nuclear Information System (INIS)

    Design and construction of a system to measure gaseous Radon 222 which arise from a source of Radium 226 electrodeposited in a stainless disc is described. Such a system allows to differentiate the energies of radium where they come from, as well as energies of daughter products. In this way it is possible to have a more precise measure of the alpha activity of this isotope. The system was constructed in a stainless steel hermetic container made of the camera, a cape and a valve, the used sample was a standards of Radium 226 attained from carnotite ore. The Radon 222 alpha particles, as well as the alpha particles of its decay products namely Polonium 210. Polonium 218 and Polonium 214 were identified by a surface barrier detector. The results in this manner obtained shows clearly well definite peaks of Radon 222 and also peaks of the Radon 222 daughter products with energies of 5.43, 5.31, 6.0 and 7.69 Mev respectively. The system allows to separate and to indentify the energies of Radon and its daughter products coming directly from a standard solid sample of Radium 226 (Author)

  16. Genesis of Uranium in the younger granites of gabal abu hawis area, central eastern desert of Egypt

    International Nuclear Information System (INIS)

    The younger granites cropping out in gabal abu hawis area are considered as uraniferous (fertile) granites (the fertile is mainly is mainly attributed to presence of radioactive zircon). Abu hawis granitic pluton is dissected by joints faults of different trends forming two mineralized shear zones in the northern peripheries and southern border. The younger granites hosting uranium mineralizations along the two mineralized shear zones. The uranium minerals include uranophane and carnotite. The altered granites have much lower Th/U ratios (0.03-0.10) than those of the fresh granites (1.69-2.05), indicating strong mobilization of uranium in this pluton by super-heated solutions that resulted from supergence meteoric water as well as U-addition by hypogene fluids. These solutions could pass through the structural network of fractures, joints and fault planes and have leached some of labile uranium from the surrounding rocks and/or the younger granites themselves. Then, changing in the physicochemical conditions of these solutions caused uranium precipitation as uranium minerals filling the cracks in the rock and/or adsorbed on the surface of clay minerals and iron oxides in the two shear zones

  17. Review of Radiotracer Applications in Geophysics in the United States of America

    International Nuclear Information System (INIS)

    The geophysical applications of radiotracers in the United States have grown steadily in number, scope, and importance since the radioactive mineral carnotite was first used in oil - well cementing operations nearly thirty years ago. Results of laboratory and field investigations with radiotracers have led to a realization and elucidation of underground conditions and events in petroleum production that would not otherwise have been possible. And still today, in cases where there are competing methods of obtaining information or performing an operation, the tracer approach often offers greater accuracy, more positive data, better operational control, or greater savings in time or money. Radiotracers are extensively used in the drilling, completion, and treatment of oil wells and in secondary recovery operations. They have proved particularly effective for following the movements of fluids in, adjacent to, and between wellbores and for following and pinpointing the stopping-place of materials introduced into wellbores. Specific applications include: the determination of production profiles; the determination of injectivity profiles and the rate and path of travel between injection and production wells; the location of cement tops; thief zones, channels, and casing leaks; the control of the placement of plugging materials; and, the determination of the number, type, and extent of fractures following stimulation. This paper reviews this application of radiotracers to geophysical problems in the USA. An aim is to evaluate the present position of the radiotracer technique with emphasis on extent of use, practical limitations, and competition from alternative techniques. (author)

  18. Environmental application of rice straw in energy production and potential adsorption of uranium and heavy metals

    International Nuclear Information System (INIS)

    The sustainable development of agricultural waste is nowadays a main strategy in producing neutral CO2 energy and metal removal technologies. In Egypt, large amounts of rice straw are annually burnt in the open air causing severe air pollution that could be directed to co-firing and adsorption technologies. On bench scale, rice straw was positively contributed in a clean and smokeless co-firing process with methanol due to the oxidizing effect of the alcohol. The co-firing temperature control is vital to develop the adsorptive character of the residual ash and to avoid prolonged time needed to improve the physical properties of the rice straw if applied directly as a biosorbent. The consumed methanol in the process ranges from 0.15 to 0.3 liter per each kg of straw depending on its compaction. The grossed heat value from such process may drive steam generator for electricity. The residual ash was subsequently cross-linked in uranium and heavy metals adsorption tests from solutions. The porous texture of the residual ash and the amorphous nature of the silica along with potassium content provide a suitable condition for uranium immobilization especially if phosphorus or vanadium exist. The resulted chemical precipitate is analogues in composition to meta-ankoleite (KUO2PO4 · 3H2O) or hydrated carnotite (K2(UO2)2V2O8) · 1-3H2O respectively. The XRD data of the latter form show an enhancement in crystallinity of the amorphous precipitate with the heated samples. (author)

  19. Application of solution-mineral equilibrium chemistry to solution mining of uranium ores

    International Nuclear Information System (INIS)

    Modern methods of uranium solution mining are typically accompanied by gains and losses of mass through reagent consumption by rock-forming minerals, with subsequent formation of clay minerals, gypsum, carbonates, and iron oxyhydroxides. A systematic approach to alleviate such problems involves the application of leach solutions that are in equilibrium with the host-rock minerals but in disequilibrium with the ore-forming minerals. This partial equilibrium can be approximated by solution-composition adjustments within the systems K2O-Al2O3SiO2-H2O and Na2O3-Al2O3SiO2-H2O. Uranium ore containing 0.15 percent U3O8 from the Gulf Mineral Resources Corporation's Mariano Lake mine, the Smith Lake district of the Grants mineral belt, was collected for investigation. Presented are a theoretical evaluation of leachate data and an experimental treatment of the ore, which contained mainly K-feldspar, plagioclase feldspar, and quartz (with lesser amounts of micas, clay minerals, and organic carbonaceous material). Small-scale (less than or equal to 1 kg) column-leaching experiments were conducted to model the results of conventional leaching operations and to provide leachate solutions that could be compared with solutions calculated to be in equilibrium with the matrix minerals. Leach solutions employed include: 1) sulfuric acid, 2) sodium bicarbonate, and 3) sulfuric acid with 1.0 molal potassium chloride. The uranium concentrations in the sodium-bicarbonate leach solution and the acid-leach solution were about a gram per liter at the termination of the tests. However, the permeability of the ore in the acid leach was greatly reduced, owing to the formation of clay minerals. Uranium solubility in the leach column stabilized with the potassium-chloride solution was calculated from leachate compositions to be limited by the solubility of carnotite

  20. Occurrence, behavior and distribution of high levels of uranium in shallow groundwater at Datong basin, northern China

    International Nuclear Information System (INIS)

    Geochemical investigations of uranium (U) occurrence in the environments were conducted at Datong basin of northern China. The results suggest that U contents were generally 22+) species is dominant and strongly adsorbed onto iron (hydro)xides, while it would be preferentially complexed with carbonate in the alkaline groundwater, forming highly soluble uranyl-carbonate complexes at Datong. Under reducing conditions, uranous (U(IV)) species is ready to precipitate or bind to organic matter, therefore having a low mobility. At the study area, high U groundwater (> 30 μg/L) occurs at the alluvial plains due to intermediate redox and enhanced alkaline conditions. The abnormally high levels of U in groundwater (> 100 μg/L) are locally found at the west alluvial plains. By contrast, U co-precipitation with secondary carbonate minerals like Ca2UO2(CO3)3 in the dominant Ca–Mg–Na–HCO3 type groundwater may prevail at the east alluvial plains. Besides, bedrocks such as Carboniferous and Permian sedimentary rocks, especially the coal-bearing strata which have higher U contents at the west mountain areas may also account for the abnormally high levels of U in groundwater. - Highlights: • High U groundwater occurs at the alluvial plains of Datong basin. • Redox state, complexation and adsorption are responsible for U enrichment. • Carboniferous and Permian sedimentary rocks have higher U contents at Datong. • Uranyl is preferentially complexed with carbonate in groundwater. • U in the aquifer sediments may be primarily associated with carnotite

  1. Uranium minerals and radioactive equilibrium in the Jordan phosphate deposit of Ruseifa

    International Nuclear Information System (INIS)

    In the open pit of Ruseifa (Jordan) a marine sedimentary succession is mined, which belongs to the Maastrichian stage (Upper Cretacious). This up to 28 m thick succession is composed of an alternated stratification of phosphorites, limestones, clay marls and cherts with gradations between these main rock types. As all these rocks contain apatite in varying amounts the whole succession is designed by the term 'phoshate layer'. In the 'phosphate layer' 4 workable phosphorite bearing beds with thicknesses between 1.15 and 3.45 m are present, giving an eminent economical importance to the deposit. Especially the stratigraphically youngest, the fourth phosphorite bed, shows remarkably increased gamma-activities. In the phoshorite the average uranium content amounts up to 110 ppm U. The mineral apatite has been identified to be the main carrier of the uranium. In veins and fissures yellow secondary uranium minerals occur, which have been determined as carnotite and metatuyamunite. The discovery, that uranium is in a state of preponderant radioactive equilibrium with its daughter products, is important for the genesis of the uranium enrichments as well as for practical means of mining. The detected radioactive disequilibria are restricted to the formation of secondary uranium minerals on fissures and joints demonstrating distinct migration of uranium and its daughter product in the last 800 000 years (quaternary until recent weathering). These young geochemical weathering processes did not essentially change the syngenetic distribution of uranium in the phosphorite. With the determined mean uranium content of 110 ppm the whole uranium reserves of Ruseifa evaluates approximately 8580 t of uranium metal out of total phosphate reserves of 78 mio. t. (orig.)

  2. The geology and geochemistry of some epigenetic uranium deposits near the Swakop River, South West Africa

    International Nuclear Information System (INIS)

    This study comprises a geological and geochemical investigation of the uranium deposits in the region near the Swakop River which extends from the Langer Heinrich Mountain in the east to the end of the Tumas River in the west. The general geology of the basement rocks in the Langer Heinrich region only is discussed. The general geology of the younger duricrust formations is discussed. Analytical methods were developed for the separation of thorium, protactinium and uranium from geological materials using various chromatographic procedures. Alpha spectrometry, neutron activation analysis and delayed neutron counting were the main techniques used. The occurrence of uranium in the region of study follows a unique geochemical cycle, and the geochemistry at each stage in the cycle was examined. The first stage in the uranium-geochemical cycle was the basement rocks. The second stage in the geochemical cycle of uranium was the subsurface water. The third stage in the geochemical cycle of uranium concerns its occurrence in the duricrust deposits. Isotopic disequilibrium measurements showed that uranium is still migrating, and that the age of the carnotite precipitation is 30 000 years, based on the open-system model of uranium migration. In the final stage of the geochemical cycle, the geochemistry of uranium in seawater and the diatomaceous muds is discussed. A classification system for the uranium deposits near the Swakop River, based on genetic relationships, is proposed and described in terms of the geochemical cycle of uranium, the mode of transport and mode of deposition. The relationships between the duricrust uranium deposits and the other uranium deposits of South Africa are compared

  3. Depletion of energy or depletion of knowledge alternative use of energy resources

    International Nuclear Information System (INIS)

    This research paper is about the depletion of Energy resources being a huge problem facing the world at this time. As available energy sources are coming to a shortage and measures are be taken in order to conserve the irreplaceable energy resources that leads to sustainability and fair use of energy sources for future generations. Alternative energy sources are being sought; however no other energy source is able to provide even a fraction of energy as that of fossil fuels. Use of the alternative energy resources like wind corridors (Sindh and Baluchistan), fair use of Hydro energy (past monsoon flooding can produce enough energy that may available for next century). Uranium Resources which are enough for centuries energy production in Pakistan (Dhok Pathan Formation) lying in Siwalick series from Pliocene to Pleistocene. Among all of these, my focus is about energy from mineral fuels like Uranium from Sandstone hosted deposits in Pakistan (Siwalik Series in Pakistan). A number of uranium bearing mineralized horizons are present in the upper part of the Dhok Pathan Formation. These horizons have secondary uranium mineral carnotite and other ores. Uranium mineralization is widely distributed throughout the Siwaliks The purpose of this paper was to introduce the use of alternative energy sources in Pakistan which are present in enough amounts by nature. Pakistan is blessed with wealth of natural resources. Unfortunately, Pakistan is totally depending on non renewable energy resource. There are three main types of fossil fuels: coal, oil and natural gas. After food, fossil fuel is humanity's most important source of energy. Pakistan is among the most gas dependent economies of the world. Use of fossil fuel for energy will not only increase the demand of more fossils but it has also extreme effects on climate as well as direct and indirect effects to humans. These entire remedial thinking can only be possible if you try to use alternative energy resources rather than

  4. A crystal-chemical investigation of phases of relevance to lime-chromite roast reactions

    International Nuclear Information System (INIS)

    The aim of this investigation was to elucidate the crystal chemistry of phases in the CaO-chromium oxide-Si-O2 system, by single crystal x-ray diffractometry. The crystal chemistry of calcium and chromium-containing phases, with chromium valencies higher than trivalent, which occur in the chromite-lime roast process has been investigated. The phases include the monocalcium, tricalcium and pentacalcium ortho-chromates and the fluor and oxy-chromium apatites. The crystal structures of Ca5Cr3O12 and Ca5Cr1.8Si1.2O12, the chromium analogues of silico-carnotite, Ca5P2SiO12, have been determined. An alternative model for the structure of Ca3(CrO4)2 has been investigated in which some of the (CrO4) tetrahedra are positionally disordered. It is proposed that the structure determined may represent an average of two different structure types and the transformation from the one polymorph to the other involves the alternate flipping of the disordered tetrahedra. The disordered model implies an alternative stoichiometry Ca10(CrO4)7 in which 6/7 of the chromium is pentavalent and 1/7 is hexavalent. The phase chemistry of mixtures of lime and chromite has been examined at temperatures above 850 0C in air. Ca5Cr3O12' Ca5(CrO4)F and Ca3(CrO4)2 are produced as relatively pure phases. Optimum chromite: lime addition is in the order 1:1, such that the product phases include Ca5Cr3O12, Ca4Fe+32Al2O10 and MgO. Reaction kinetics are however unfavourable. By replacing 7% CaO with CaF2, the kinetics are improved. The product phases are fluor-chromium apatite Ca5Cr3O10F, Ca4Fe+32Al2O12 and MgO. The apatite, like Ca5Cr3O12, may be preferentially leached with dilute acid

  5. Uranium roll-front deposits in the southern Black Hills, South Dakota

    International Nuclear Information System (INIS)

    In the southern Black Hills of South Dakota, uranium roll-type deposits are present in early Cretaceous Lakota Formation sandstone. Analysis of a 45-Foot drill core, representing a vertical section through the nose of the roll-front, by scanning X-ray fluorescence (XRF), standard XRF, X-ray diffraction (XRD), organic petrography, electron microprobe, and scanning electron microscopy (SEM) is underway. The core is lithologically composed of an orthoquartzite with varying amounts of chert and consists of an oxidized zone, four reduced zones, and three ore zones. The oxidized zone is characterized by medium- to fine-grained, well-sorted, well-rounded orthoquartzite with minor hermatitic kaolinite weakly cementing and coating quartz grains. Reduced zones have angular to rounded, medium- to fine-grained gray to black quartz grains; coarse-grained, angular, white to black chert; thin laminae and small isolated fragments of carbonaceous material with pyrite. Ore zones are composed of trough cross-bedded, poorly-cemented, well-sorted mixtures of rounded quartz grains and angular to rounded chert with yellow to olive-green uranium- and vanadium-rich clays, and carbonaceous material with pyrite. The chemistry of the entire core was determined by scanning X-ray fluorescence for 46 elements. In the oxidized, reduced, and ore zones, uranium and vanadium averaged 40 ppm U and 3300 ppm V, 800 ppm U and 3000 ppm V, and 3800 ppm U and 5000 ppm V, respectively. No uranium or vanadium minerals have been found by XRD or microprobe analysis. However, certain segments of the core are enriched in U and V, including those with high clay content. Preliminary SEM analyses have shown smectite, kaolinite, and possibly illite as coatings on quartz grains. U and V are present in some of the clay coatings, and probable carnotite and an authigenic vanadium mineral were found. Carbonaceous laminae are present in the reduced and ore zones and commonly contain pyrite with associated uranium. (author

  6. A review of uranium minerals exploration in Ethiopia

    International Nuclear Information System (INIS)

    Full text: Radioactive minerals such as uraninite, UO2, thorianite, ThO2, thorite, ThSiO4, and the like have been valuable for their uranium and thorium contents which are becoming important energy resources today in many countries where atomic reactors are used. They are also essential ingredients in modern weapon industries for the manufacture of devastating weapons. Uraninite is the chief source of uranium although other minerals are important sources of the element such as carnotite, K2(UO2)2(VO4).3H2O, Tyuyamunite, Ca(UO2)2(VO4).5-8 1/2 H2O, torbernite, Cu(UO2)2(PO4)2.8-12H2O,and autunite (Hurlbut et.al, 1977). Th can substitute for U and a complete series between uraninite and thorianite occurs. Analyses usually show the presence of small amounts of Pb, Ra, Ce, Y, N, He and A. Lead occurs as one of two stable isotopes (Pb206 and Pb207) which result from the radioactive decay of uranium (Hurlbut et.al. 1977). According to Bill Morton, a pioneer in the study of Ethiopian Minerals and Rocks, there are a number of radioactive minerals in Ethiopia, with varying physical properties. The presence of the radioactive minerals can easily be detected using a geiger counter or scintillation counter.These radioactive minerals are mainly found in small amounts in pegmatites and in some sandstones reported from the Hararghe area, south-eastern Ethiopia. Uraninite occurs in a form of pitchblende, which is massive with a banded structure. To date no extensive radioactive mineral deposits have been discovered in Ethiopia. Besides the Uranium and thorium minerals observed in pegmatite veins belonging to gneisses of Hararge, Precambrian granite as well as Cretaceous and Jurassic sediments in the same region, i.e., south eastern Ethiopia, particularly in the Dire-Dawa - Harar area, seem to be favorable host rocks for radioactive minerals (Getaneh Assefa, 1992). There are also reports of occurrences of radioactive minerals in Sidamo (Wadera, Zenbaba and Genale localities), Kaffa

  7. Experimental investigation of uranium-series isotope mobility in a basaltic weathering profile

    Science.gov (United States)

    Dosseto, Anthony; Menozzi, Davide; Kinsley, Leslie

    2015-04-01

    the preferential dissolution of a soluble phase, depleted in 234U relative to 238U as a result of alpha recoil of 234Th into a more resistant phase. In contrast, (234U/238U) ratios show little variation in the soil, suggesting further hydrolysis has little effect on the U isotope ratio of residual primary minerals in the soil. These results illustrate the complexity of U-series isotope behaviour during chemical weathering. While sequential extraction is a recommended approach to isolate primary minerals and follow their isotopic evolution during regolith formation, it also uncovers that U-series isotope mobility is more diverse than previously postulated. Reference [1] Sheng, Z., Kuroda, P., 1986a. Isotopic fractionation of uranium: Extremely high enrichments of 234U in the acid-residues of a Colorado carnotite. Radiochim. Acta 39, 131-138.