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Sample records for analcime

  1. Removal of radionuclides by analcime-bearing rocks

    International Nuclear Information System (INIS)

    The study of the removal of radionuclides (uranium, radium and thorium) in static conditions from aqueous solutions by analcime-bearing rocks and pure analcime was carried out. The high removal efficiency of all studied radionuclides by analcime-bearing rocks was determined. Analcime was efficient in removing of thorium only

  2. Preparation and characterisation of analcime powders

    Czech Academy of Sciences Publication Activity Database

    Novotná, Martina; Šatava, Vladimír; Maixner, J.; Kloužková, A.; Kostka, Petr; Ležal, Dimitrij

    2003-01-01

    Roč. 5, č. 5 (2003), s. 1405-1409. ISSN 1454-4164 R&D Projects: GA ČR GA104/03/0031 Institutional research plan: CEZ:AV0Z4032918 Keywords : analcime * leucite * hydrothermal synthesis Subject RIV: CA - Inorganic Chemistry Impact factor: 0.996, year: 2003

  3. The exchange of tritiated water between natural zeolite analcime and surrounding water

    International Nuclear Information System (INIS)

    Natural zeolite Analcime has been considered as a possible sorbent and storage material for tritiated water. The kinetics of tritiated water release from analcime crystals of two size fractions (20-50 and 50-80 μm dia.) into surrounding water has been investigated at 25-60 0C. At 25 0C the half-life of THO/H2O exchange for the smaller and larger beads is about 1.3 and 5.0 hours, respectively. This is higher than the corresponding results obtained with synthetic analcime, but still of the same order of magnitude. The difference is ascribed to the presence of mineral impurities in natural analcime. If the natural mineral could be processed into particles of 2-5 mm radius, that material might be useful as a storage for tritiated waste water. 6 refs.; 3 figs

  4. Development of empirical equation for analcime in the treatment of nuclear waste

    International Nuclear Information System (INIS)

    Highlights: ► An empirical correlation is proposed. ► Simplicity of the empirical correlation is very important. ► Tests have shown that correlation is excellent. - Abstract: A novel description has been provided by the modeling of adsorption behavior of the analcime zeolite. Based on the data obtained by an experimental research, models were developed on the natural and synthesized analcime for the adsorption of the radioisotopes of Rb+, Cs+, and Sr2+ at high temperatures using tablecurve and eviews software. In the batch operation, the best adsorption equation was presented. The results which revealed the following equation was the best choice: logN=c1+c2logT+c3logKd+c4Kd Therefore the empirical equation is recommended for the effective estimation of adsorption amount of the analcime zeolite within a shorter time at higher temperatures.

  5. Transformation of analcime into IMF structure during the synthesis of IMF zeolite

    Czech Academy of Sciences Publication Activity Database

    Kubů, Martin; Přech, Jan

    2015-01-01

    Roč. 206, APR 2015 (2015), s. 121-126. ISSN 1387-1811 R&D Projects: GA ČR GP13-17593P Institutional support: RVO:61388955 Keywords : IMF zeolite * analcime * crystallization Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 3.453, year: 2014

  6. Preparation and characterization of analcime powders by x-ray and sem analyses

    Czech Academy of Sciences Publication Activity Database

    Kohoutková, Martina; Kloužková, A.; Maixner, J.; Mrázová, M.

    2007-01-01

    Roč. 51, č. 1 (2007), s. 9-14. ISSN 0862-5468 R&D Projects: GA MPO 2A-1TP1/063 Institutional research plan: CEZ:AV0Z40320502 Keywords : analcime * hydrothermal synthesis * X-ray diffraction Subject RIV: CA - Inorganic Chemistry Impact factor: 0.488, year: 2007

  7. Natural zeolites chabazite/phillipsite/analcime increase blood levels of antioxidant enzymes

    OpenAIRE

    Dogliotti, Giada; Malavazos, Alexis E.; Giacometti, Sonia; Solimene, Umberto; Fanelli, Mauro; Corsi, Massimiliano M; Dozio, Elena

    2011-01-01

    Imbalance between reactive oxygen species generation and antioxidant capacity induces a condition known as oxidative stress which is implicated in numerous pathological processes. In this study we evaluated whether natural zeolites chabazite/phillipsite/analcime may affect the levels of different antioxidant enzymes (gluthatione peroxidase, superoxide dismutase, gluthatione reductase), total antioxidant status and oxidative stress in 25 clinically healthy men, both non-smokers and smokers. Me...

  8. Investigation of the mechanism of interaction at the hydrothermal conditions of zeolite – cubic analcime with the Li+, Mg2+, Sr2+ and Fe3+ ions

    Directory of Open Access Journals (Sweden)

    Asta TRAIDARAITĖ

    2013-09-01

    Full Text Available Analcime and clinoptilolite are among the most abundant zeolites in nature. During recent decades natural analcimes and clinoptilolites, also synthetic modified analcimes have been investigated as potential and innovative substances, possible to use for the immobilization of radioactive waste, molecular catalysis and other purposes. However, natural analcimes like many natural rocks are contamined with various impurities (about 30 %, which significally reduces their sorption possibilities and possibilities of their using in such chemical technologies as catalysis, fractioning of hydrocarbons and other. In this article the stability of cubic analcime at the hydrothermal conditions at 180 °C temperature in solutions of various concentrations, containing Li+, Mg2+, Sr2+ and Fe3+ ions has been examined. These processes have big signification for the formation of ion-exchanged analcimes, its sorption properties and also if ions have been immobilized in analcime structure. It has been established, that as result of interaction between cubic analcime and lithium chloride solutions the formation of new compounds: lithium silicate and silinaite occurs. At the same hydrothermal conditions the interaction between cubic analcime and chloride solutions, containing Sr2+, Mg2+ and Fe3+ ions pass without formation of new compounds, and only with interposition of these ions in the structure of cubic analcime. DOI: http://dx.doi.org/10.5755/j01.ms.19.3.1496

  9. Review of stabilities of analcime and some calcium zeolites. [Stilbite, lawsonite, prebnite, laumontite, and wairakite

    Energy Technology Data Exchange (ETDEWEB)

    Liou, J.G.

    1977-02-01

    Many laboratory experiments have been performed on the stabilities of analcime, stilbite, laumontite, wairakite, lawsonite and prehnite. Stabilities reported for most experiments in which fluid pressure equals 2 kb total pressure are: stilbite--less than 170/sup 0/C, laumontite--170/sup 0/ to 280/sup 0/C, and wairakite--280/sup 0/ to 385/sup 0/C. These three minerals are stable only below 3 kb fluid pressure. At higher fluid pressures, laumontite breaks down to lawsonite + quartz + H/sub 2/O, and wairakite reacts with H/sub 2/O to form prehnite + montmorillonite + quartz. Analcime + quartz together are stable below 4 kb and 200/sup 0/C. Under conditions where fluid pressure is less than total pressure, the stability fields of these zeolites are encroached by those of blueschist facies and prehnite-pumpellyite facies minerals in the higher pressure region and by those of greenschist facies minerals in the higher temperature region. At lower H/sub 2/O activities caused by dissolved substances, these zeolites would occur at lower P--T conditions than those determined by the experiments. For example, the upper stability temperature of laumontite is about 10/sup 0/C lower in an 0.25 N NaCl solution. Laumontite is stable in the CO/sub 2/-bearing fluid at 1 kb fluid pressure and 260/sup 0/C with maximum mol fraction of CO/sub 2/ of 0.023. At higher CO/sub 2/ contents, calcite + montmorillonite + quartz are stable. The stability data for these zeolites, together with our recent results on the relations of pumpellyite, prehnite-lawsonite, and wairakite-anorthite, permit delineation of the P--T paths for various observed mineral parageneses documented in the literature.

  10. A vibrational spectroscopic study of the silicate mineral analcime - Na2(Al4SiO4O12)·2H2O - A natural zeolite

    Science.gov (United States)

    Frost, Ray L.; López, Andrés; Theiss, Frederick L.; Romano, Antônio Wilson; Scholz, Ricardo

    2014-12-01

    We have studied the mineral analcime using a combination of scanning electron microscopy with energy dispersive spectroscopy and vibrational spectroscopy. The mineral analcime Na2(Al4SiO4O12)·2H2O is a crystalline sodium silicate. Chemical analysis shows the mineral contains a range of elements including Na, Al, Fe2+ and Si. The mineral is characterized by intense Raman bands observed at 1052, 1096 and 1125 cm-1. The infrared bands are broad; nevertheless bands may be resolved at 1006 and 1119 cm-1. These bands are assigned to SiO stretching vibrational modes. Intense Raman band at 484 cm-1 is attributed to OSiO bending modes. Raman bands observed at 2501, 3542, 3558 and 3600 cm-1 are assigned to the stretching vibrations of water. Low intensity infrared bands are noted at 3373, 3529 and 3608 cm-1. The observation of multiple water bands indicate that water is involved in the structure of analcime with differing hydrogen bond strengths. This concept is supported by the number of bands in the water bending region. Vibrational spectroscopy assists with the characterization of the mineral analcime.

  11. Review of the thermal stability and cation exchange properties of the zeolite minerals clinoptilolite, mordenite, and analcime; applications to radioactive waste isolation in silicic tuff

    International Nuclear Information System (INIS)

    Silicic tuffs of the southern Great Basin and basalts of the Columbia River Plateau are under investigation as potential host rocks for high- and intermediate-level radioactive wastes. Nonwelded and partially welded tuffs may contain major amounts (> 50%) of the zeolite minerals clinoptilolite, mordenite, and analcime. Densely welded tuffs and some basalt flows may contain clinoptilolite as fracture filling that limits the permeability of these rocks. The cation exchange properties of these zeolite minerals allow them to pose a formidable natural barrier to the migration of cationic species of various radionuclides in aqueous solutions. However, these minerals are unstable at elevated temperatures and at low water-vapor pressures and may break down either by reversible dehydration or by irreversible mineralogical reactions. All the breakdown reactions occurring at increased temperature involve a net volume reduction and evolution of fluids. Thus, they may provide a pathway (shrinkage fractures) and a driving force (fluid pressure) for release of radionuclides to the biosphere. These reactions may be avoided by keeping zeolite-bearing horizons saturated with water and below about 850C. This may restrict allowable gross thermal loadings in waste repositories in volcanic rocks

  12. Efeito do glutaraldeído na adsorção de extrato proteico da Ipomoea Batatas (L Lam na superficie de uma zeólita analcima Effect of the glutaraldeide on the adsorption of proteic extract of the Ipomoea Batatas (L Lam in analcime zeolite surface

    Directory of Open Access Journals (Sweden)

    A. C. S. Gondim

    2005-09-01

    Full Text Available A zeólita analcime (Na16Al16Si32O96.nH 2O foi submetida a ataque ácido com HCl 0,25 mol.L-1, seguido da funcionalização com glutaraldeído, foi imersa em extrato protéico obtido da polpa da batata-doce (Ipomoea Batatas (L Lam, que tem em sua composição a enzima polifenol oxidase (PFO. As amostras foram submetidas a procedimentos de caracterização por microscopia eletrônica de varredura, espectroscopia na região do infravermelho com transformada de Fourier e termogravimetria.The analcime zeolite (Na16Al16Si32O96.nH2O was treated with hydrochloric acid 0.25 mol.L-1, followed by the funcionalization with glutaraldehyde and immersed in the proteic extract obtained from gross extract of sweet potato pulp (Ipomoea Batatas (L Lam, which presents in its composition the polyphenol oxidase enzyme (PPO. Other samples were submitted to the same procedure with characterizations by scanning electron microscopy, Fourier Transform Infrared spectroscopy and thermogravimetry.

  13. Progress report on the kinetic measurements of the reactions of the silicates at the Yucca Mountain potential repository site. [Final] report, June 15, 1993--September 30, 1993

    International Nuclear Information System (INIS)

    Preliminary results are provided on: Synthesis and characterization of analcime and Na-clinoptilolite (Penn State), batch solubility experiments on analcime and clinoptilolite, thermodynamic modelling of solubility data, and kinetic flow-through experiments on analcime and clinoptilolite

  14. Analcite formation in the Agades Region (Niger)

    International Nuclear Information System (INIS)

    A study based mainly upon field mapping and drill cores examination, followed by a laboratory survey allows us to support a genetic hypothesis upon the formation of analcime in the 'Continental intercalaire' of Agades (Niger). Analcime could be generated from an early diagenesis of argillaceous sediments influenced by high soda content fossil waters inside confined continental sedimentary basins. (authors)

  15. Tritiated waste water fixation of solid materials

    International Nuclear Information System (INIS)

    The exchange kinetics between tritiated and distilled water (THO/H2O) from various zeolites, natural and synthetic analcimes, saturated with THO are reported. Kinetic parameters for the diffusion process are calculated from experimental data. Tritiated water releases from the zeolites saturated with THO into distilled water is given for various temperatures and times. Ferric, zinc, cobalt and sodium zeolites are investigated. Results indicated that cobalt zeolite and synthetic analcime release rates of THO are superior to the other zeolites tested

  16. Zeolite rocks from the paleogene lacustrine volcano-sedimentary deposits in Gorna Glogovitsa Graben (Kraishte region, Western Bulgaria)

    International Nuclear Information System (INIS)

    Analcime-clinoptilolite and clinoptilolite-analcime zeolite rocks established in the Paleogene deposits of Gorna Glogovitza Graben are the forth Tertiary zeolite rocks deposit in Western Bulgaria. Terrigenous and abiogenic (calcareous) lacustrine sedimentation in the Graben has been influenced of process(es) of acid ash pyroclastics deposition. Pyroclastic material constitutes of glass-shards, pumice fragments (with plagioclase, biotite, amphibole and scarce sanidine microphenocrysts), crystalloclasts and cognate phenorhyolitic-penorhyodacitic fragments. Glassy components have been completely transformed according to the following reactions' sequence: volcanic glass →clinoptilolite → analcime → K-feldspar. Such an authigenic silicate association formed in lacustrine environment is interpreted as characteristic of high salinity (about 50000 ppm) and high pH value (nearly 9.5) of the basin/pore wa-ter. The environments in which Gorna Glogovitza Graben and other Bulgarian and Serbian Tertiary analcime rocks were formed can be hardly compared. A suggestion about a similar environment of analcime formation in Gorna Glogovitza Graben and Slanci basin (near Belgrade, Serbia) can be made based on the very close cell parameters of the analcime (respectively a0 = 13.70980 A, cell volume = 2576.87 A3 and a0 13.699-13.707 A, cell volume - 2571-2575 A3)

  17. Clay minerals in uraniferous deposit of Imouraren (Tim Mersoi basin, Niger): implications on genesis of deposit and on ore treatment process

    International Nuclear Information System (INIS)

    Nigerian uraniferous deposits are located in carboniferous and Jurassic formations of Tim Mersoi basin. AREVA is shareholder of 3 mine sites in this area: SOMAIR and COMINAK, both in exploitation since 1960's and IMOURAREN, 80 km further South, whose exploitation is planned for 2015. Mineralization of Imouraren deposit is included in the fluvial formation of Tchirezrine 2 (Jurassic), composed of channels and flood plains. Facies of channel in-fillings range from coarse sandstones to siltstones, while overflow facies are composed of analcimolites. Secondary mineralogy was acquired during 2 stages: 1- diagenesis, with formation of clay minerals, analcime, secondary quartz and albites, and 2- stage of fluids circulations, which induced alteration of detrital and diagenetic minerals, formation of new phases and uranium deposition. A mineralogical zoning, at the scale of deposit resulted from this alteration. The heterogeneity of Tchirezrine 2, at the level of both facies and mineralogy, is also evidenced during ore treatment, as ore reacts differently depending on its source, with sometimes problems of U recovery. Ore treatment tests showed that analcimes and chlorites were both penalizing minerals, because of 1- the sequestration of U-bearing minerals into analcimes, 2- their dissolution which trends to move away from U solubilization conditions (pH and Eh) and to form numerous sulfates, and 3- problems of percolation. A detection method of analcime-rich ores, based on infrared spectroscopy, was developed in order to optimize ore blending and so to reduce negative effects during ore treatment process. (author)

  18. Mineral X, a new thalcusite homologue from the Ilimaussaq complex, south Greenland

    DEFF Research Database (Denmark)

    Makovicky, Emil; Karup-Møller, Sven

    2011-01-01

    Mineral X is assumed to be a new member of the thalcusite homologous series with the structural formula TlCu2NS2N+1 with N=1.5. It was found in loose ussingite-analcime boulders on the Taseq slope towards the Narsaq Elv in the northern part of the Ilímaussaq complex in South Greenland in associat...

  19. Mineral X, a new thalcusite homologue from the Ilimaussaq complex, South Greenland Contribution to the mineralogy of Ilimaussaq, no. 144

    DEFF Research Database (Denmark)

    Karup-Møller, Sven; Makovicky, E.

    2011-01-01

    Mineral X is assumed to be a new member of the thalcusite homologous series with the structural formula TlCu2NS2N+1 with N=1.5. It was found in loose ussingite-analcime boulders on the Taseq slope towards the Narsaq Elv in the northern part of the Ilimaussaq complex in South Greenland in associat...

  20. Effects of alteration product precipitation on glass dissolution

    International Nuclear Information System (INIS)

    Highlights: • Calculations differ between kinetically-controlled and thermodynamic precipitation. • There is an initial increase in dissolution rate when analcime precipitates. • Analcime precipitation rate affects glass rate initially, but glass controls at long time. - Abstract: Understanding the mechanisms that control the durability of nuclear waste glass is paramount if reliable models are to be constructed so that the glass dissolution rate in a given geological repository can be calculated. Presently, it is agreed that (boro)silicate glasses dissolve in water at a rate dependent on the solution concentration of orthosilicic acid (H4SiO4) with higher [H4SiO4] leading to lower dissolution rates. Once the reaction has slowed as a result of the buildup of H4SiO4, another increase in the rate has been observed that corresponds to the precipitation of certain silica-bearing alteration products. However, it has also been observed that the concentration of silica-bearing solution species does not significantly decrease, indicating saturation, while other glass tracer elements concentrations continue to increase, indicating that the glass is still dissolving. In this study, we have used the Geochemist’s Workbench code to investigate the relationship between glass dissolution rates and the precipitation rate of a representative zeolitic silica-bearing alteration product, analcime [Na(AlSi2O6)⋅H2O]. To simplify the calculations, we suppressed all alteration products except analcime, gibbsite (Al(OH)3), and amorphous silica. The pseudo-equilibrium-constant matrix for amorphous silica was substituted for the glass pseudo-equilibrium-constant matrix because it has been shown that silicate glasses act as a silica-only solid with respect to kinetic considerations. In this article, we present the results of our calculations of the glass dissolution rate at different values for the analcime precipitation rate constant and the effects of varying the glass dissolution

  1. Experimental alteration of basalt glass applied to the alteration of nuclear waste glass

    International Nuclear Information System (INIS)

    The main objective of the experiments was to produce in the laboratory an altered basalt glass similar to basalt glass altered in a natural environment. This objective has been accomplished with a very good correlation between the observed alteration of basalt glass in a natural environment with that in the laboratory. The formation of the amorphous hydration layer, smectite, analcime, calcium carbonate, and thomsonite all have been observed in natural glass samples that have undergone palagonitization. The SRL 165 glass reacts to a greater extent than the synthetic basalt glass under the same conditions. The alteration of SRL 165 glass produced a smectite clay, analcime, and gyrolite similar to that produced by the synthetic basalt glass

  2. Kinetic measurements on the silicates of the Yucca Mountain potential repository. Final report for October 1994--September 1995

    International Nuclear Information System (INIS)

    This Final Report includes a summary and discussion of results obtained under this project on the solubilities in subcritical aqueous solutions of Mont St. Hilaire analcime, Wikieup analcime, and Castle Creek Na-clinoptilolite. Also included here are the methods and results of hydrothermal flow-through experiments designed to measure the rates of Na-clinoptilolite dissolution and precipitation at 125 degree C. In this report, high-temperature solubility measurements made in our lab are integrated and discussed along with the low-temperature measurements made at Yale University. The final report prepared by the group at Yale University (Lasaga et al.) includes a synthesis of dissolution rate measurements made between 25 degree and 125 degree C on the Na-clinoptilolite

  3. The ion-exchange capacity and Cs, Sr leachability of natural clinoptilolites at 200--300 C and PH{sub 2}O{sub sat}

    Energy Technology Data Exchange (ETDEWEB)

    Redkin, A.F. [Russian Academy of Sciences, Moscow (Russian Federation). Inst. of the Geology of Ore Deposits; Hemley, J.J.; Doughten, M.W.; Cygan, G.L. [Geological Survey, Reston, VA (United States)

    1995-12-31

    Clinoptilolites of three US clinoptilolite-rich tuff deposits, with different alkali and alkaline earth element mole ratios, were used for experimental investigation. The runs on stability and sorption ability were carried out in water and 0.3 molal chloride solution, using individual minerals and using assemblages containing microcline and analcime at 200 to 300 C and PH{sub 2}O{sub sat} water (duration of one month and two weeks). The clinoptilolites showed different behavior, unrelated to exchange capacity, when run under similar conditions. It was also found that Cs-bearing clinoptilolites contained 12--14 wt.% Cs after runs in 0.1mNaCl+0.1mKCl+ 0.1mCsCl, whereas Sr-bearing clinoptilolite contained about 3--5% Sr in 0.1mNaCl+0.1mKCl+0.05mSrCl{sub 2}. The compositional trend showed some linear variation between Sr and Cs content and Si/Al mole ratio up to Si/Al=5.0. Thermal investigation showed that (Na-K)rich clinoptilolite completely decomposes at 325 C, (Na-Mg) rich at 350 C and (Ca-Mg) rich at 375 C in runs of 2 weeks duration in pure water. Na-analcimes associated with clinoptilolites have low Cs and Sr adsorption capacity relative to the clinoptilolites. Na-Sr -bearing analcimes have an inverse dependence of Sr/(Sr+Na+K) mole ratio with Si/Al in the reaction of heterovalent exchange in analcime, where Na and Si replace Sr and Al. Thermodynamic calculation was done for the solubility of Cs and Sr-bearing clinoptilolites at 300 C, PH{sub 2}O{sub sat}. It was established that under some conditions Sr leachability from Sr-bearing clinoptilolite is insignificant whereas Cs-bearing clinoptilolite leachability is considerably higher.

  4. Zeolite occurrence and genesis in the Late-Cretaceous Cayo arc of Coastal Ecuador: Evidence for zeolite formation in cooling marine pyroclastic flow deposits

    OpenAIRE

    Machiels, L.; Garces, D. (D.); Snellings, R.; Vilema, W.; Morante, F.; C Paredes; ELSEN, J

    2014-01-01

    This paper describes the quantitative mineralogy, the mineral chemistry and the distribution of natural zeolites over the outcrop area of the Late Cretaceous Cayo Formation of Coastal Ecuador (>1000 km(2)) and develops a model for zeolite alteration in the Cayo volcanic arc. Different zeolite types were identified: Ca-heulandite-type zeolites (clinoptilolite and heulandite), mordenite, laumontite, analcime, stilbite, epistilbite, chabazite, thomsonite and erionite. Zeolites occur over nearly ...

  5. Zeolitization of Tuffaceous Rocks in the Kesan Region, Thrace, Turkey

    OpenAIRE

    Esenli, F.; Uz, B.; Suner, F.; Esenli, V.; Ece, O.I.; Kumbasar, I.

    2005-01-01

    A 33 metre thick pyroclastic-rich zone of the Mezardere formation of Oligocene age is exposed in the Kesan region of Thrace, Turkey. In this zone, vitreous tuffs of dacitic composition have altered primarily to zeolites, including mordenite, heulandite–clinoptilolite and analcime. Silicification and alteration to clay minerals are common. Zeolite minerals have developed from volcanic glass, whereas some mordenites have formed from dissolution of heulandite-group zeolites. Although authigenic ...

  6. Geochemical investigations related to the Yucca Mountain environment and potential nuclear waste repository

    International Nuclear Information System (INIS)

    This report presents final results of the Geochemistry Research Project conducted at the Center for Nuclear Waste Regulatory Analyses (CNWRA) for the Nuclear Regulatory Commission (NRC) Office of Nuclear Regulatory Research. The study focused on experimental determinations and theoretical interpretations of fundamental thermodynamic and kinetic properties of minerals and reactions that characterize geochemical processes at the proposed nuclear waste repository site at Yucca Mountain and that could affect the capacity of the site to isolate nuclear waste. Technical results are presented in three major sections covering (i) cation exchange studies on clinoptilolite, (ii) kinetic and solubility studies on analcime and Na-clinoptilolite, and (iii) conceptual and numerical geochemical modeling of natural and repository systems. Experimental studies were designed to advance knowledge of the fundamental properties of the zeolite minerals clinoptilolite and analcime through controlled tests at 25 degrees C, and to interpret the data in the context of the geochemical system at Yucca Mountain. Cation exchange equilibria were determined for clinoptilotite and binary solutions of Na+ with K+, Ca2+, and Sr2+ at several solution concentrations. Results were interpreted using a Margules solid solution model for clinoptilolite coupled with a Pitzer activity coefficient model for aqueous solutions. Experimental data for analcime and clinoptilolite dissolution rates were interpreted using postulated rate mechanisms, and corresponding rate constants were determined. Dissolution rate data for analcime can be rationalized by alternate mechanisms which invoke either the presence of ultrareactive material or rate dependence on aqueous aluminum. Reversed solubility determinations were interpreted to obtain equilibrium constants for dissolution reactions and standard state Gibbs free energies of formation of the minerals

  7. EFFECT OF QUARTZ/MULLITE BLEND CERAMIC ADDITIVE ON IMPROVING RESISTANCE TO ACID OF SODIUM SILICATE-ACTIVATED SLAG CEMENT. CELCIUS BRINE.

    Energy Technology Data Exchange (ETDEWEB)

    SUGAMA, T.; BROTHERS, L.E.; VAN DE PUTTE, T.R.

    2006-06-01

    We evaluated the usefulness of manufactured quartz/mullite blend (MQMB) ceramic powder in increasing the resistance to acid of sodium silicate-activated slag (SSAS) cementitious material for geothermal wells. A 15-day exposure to 90{sup o} CO{sub 2}-laden H{sub 2}SO{sub 4} revealed that the MQMB had high potential as an acid-resistant additive for SSAS cement. Two factors, the appropriate ratio of slag/MQMB and the autoclave temperature, contributed to better performance of MQMB-modified SSAS cement in abating its acid erosion. The most effective slag/MQMB ratio in minimizing the loss in weight by acid erosion was 70/30 by weight. For autoclave temperature, the loss in weight of 100 C autoclaved cement was a less than 2%, but at 300 C it was even lower. Before exposure to acid, the cement autoclaved at 100 C was essentially amorphous; increasing the temperature to 200 C led to the formation of crystalline analcime in the zeolitic mineral family during reactions between the mullite in MQMB and the Na from sodium silicate. In addition, at 300 C, crystal of calcium silicate hydrate (1) (CSH) was generated in reactions between the quartz in MQMB and the activated slag. These two crystalline phases (CSH and analcime) were responsible for densifying the autoclaved cement, conveying improved compressive strength and minimizing water permeability. The CSH was susceptible to reactions with H{sub 2}SO{sub 4}, forming two corrosion products, bassanite and ionized monosilicic acid. However, the uptake of ionized monosilicic acid by Mg dissociated from the activated slag resulted in the formation of lizardite as magnesium silicate hydrate. On the other hand, the analcime was barely susceptible to acid if at all. Thus, the excellent acid resistance of MQMB-modified SSAS cement was due to the combined phases of lizardite and analcime.

  8. Coupling between mineral reactions, chemical changes in groundwater, and earthquakes in Iceland

    Science.gov (United States)

    Andrén, Margareta; Stockmann, Gabrielle; Skelton, Alasdair; Sturkell, Erik; Mörth, Carl-Magnus; Guðrúnardóttir, Helga Rakel; Keller, Nicole Simone; Odling, Nic; Dahrén, Börje; Broman, Curt; Balic-Zunic, Tonci; Hjartarson, Hreinn; Siegmund, Heike; Freund, Friedemann; Kockum, Ingrid

    2016-04-01

    Chemical analysis of groundwater samples collected from a borehole at Hafralækur, northern Iceland, from October 2008 to June 2015 revealed (1) a long-term decrease in concentration of Si and Na and (2) an abrupt increase in concentration of Na before each of two consecutive M > 5 earthquakes which occurred in 2012 and 2013, both 76 km from Hafralækur. Based on a geochemical (major elements and stable isotopes), petrological, and mineralogical study of drill cuttings taken from an adjacent borehole, we are able to show that (1) the long-term decrease in concentration of Si and Na was caused by constant volume replacement of labradorite by analcime coupled with precipitation of zeolites in vesicles and along fractures and (2) the abrupt increase of Na concentration before the first earthquake records a switchover to nonstoichiometric dissolution of analcime with preferential release of Na into groundwater. We attribute decay of the Na peaks, which followed and coincided with each earthquake to uptake of Na along fractured or porous boundaries between labradorite and analcime crystals. Possible causes of these Na peaks are an increase of reactive surface area caused by fracturing or a shift from chemical equilibrium caused by mixing between groundwater components. Both could have been triggered by preseismic dilation, which was also inferred in a previous study by Skelton et al. (2014). The mechanism behind preseismic dilation so far from the focus of an earthquake remains unknown.

  9. Synthesis of nanosized ZSM-5 zeolite using extracted silica from rice husk without adding any alumina source

    Science.gov (United States)

    Sari, Zahra Ghasemi Laleh Vajheh; Younesi, Habibollah; Kazemian, Hossein

    2015-08-01

    The synthesis of analcime and nanosized ZSM-5 zeolites was carried out by a hydrothermal method with silica extracted from rice husk, available as an inexpensive local biowaste, and without the use of an extra alumina source. Amorphous silica (with 88 wt% of SiO2) was extracted from rice husk ash by a suitable alkali solution. The effects of crystallization temperature, time and SiO2/Al2O3 ratio of the initial system on the properties of final products were investigated. For the characterization of the synthesized product, X-ray diffraction, scanning electron microscope, energy dispersive X-ray techniques, Fourier transform infrared and Brunauer-Emmett-Teller method were applied. Crystallinity percentages of analcime and nanosized ZSM-5 were 95.86 and 89.56, respectively, with specific surface area of 353.5 m2 g-1 for ZSM-5. The experimental results revealed that the synthesis of analcime and nanosized ZSM-5 zeolites was more practical with using silica extracted from inexpensive raw materials, while the whole crystallization process was accomplished without adding any alumina source during.

  10. Fundamental study on HLW glass corrosion and mineralization

    International Nuclear Information System (INIS)

    A large number of studies on aqueous corrosion of HLW glass have shown that the glass react with water to form more stable solid phases (alteration-phases or secondary phases). The process of alteration-phase formation is expected to play an important role in the radionuclide release from the glass, because it can affect both the glass dissolution rate and the retention of radio nuclides in the phases. Recent studies have indicated that analcime (zeolite) forms during aqueous corrosion of the glass in certain conditions, and the analcime formation can accelerate the glass corrosion by consuming orthosilicic acid (H4SiO4) from the solution. On the other hand, the alteration-phases such as zeolite and smectite are expected to have a retention capacity for some radio nuclides by sorption or incorporation. Therefore, a sound understanding of the alteration phase formation is expected to be essential for validation of the long-term performance. The purpose of this study is to understand, qualitatively and quantitatively, the alteration-phase formation and associated elemental release during aqueous corrosion of HLW glass. Static corrosion tests were performed with a simulated HLW glass, P0798 glass, in NaOH solutions at elevated temperatures, in order to accelerate the reaction, as a function of temperature, time and NaOH concentration. Crystalline alteration-phases formed in the corroded glass were analyzed by use of XRD, and the solution concentrations of dissolved elements were measured by use of ICP-MS. The results indicated that; 1) Analcime or Na-beidellite or both of them form during the corrosion depending on the conditions, 2) Si rich amorphous phases are contained in the alteration-phases, 3) In addition to solution pH, solution concentrations of Na and K sensitively affect formation of analcime and Na-beidellite, 4) Analcime formation accelerates the glass corrosion, 5) Most of Cs in the glass is retained in the alteration-phases by sorption onto Na

  11. Geochronology and geochemistry of Eocene-aged volcanic rocks around the Bafra (Samsun, N Turkey) area: Constraints for the interaction of lithospheric mantle and crustal melts

    Science.gov (United States)

    Temizel, İrfan; Arslan, Mehmet; Yücel, Cem; Abdioğlu, Emel; Ruffet, Gilles

    2016-08-01

    40Ar-39Ar age, whole-rock chemical, and Sr-Nd isotope data are presented for the post-collisional, Eocene (51.3-44.1 Ma)-aged volcanic rocks from the Bafra (Samsun) area in the western part of the Eastern Pontides (N Turkey) aiming to unravel their sources and evolutionary history. The studied Eocene volcanic rocks can be divided into two groups: analcime-bearing (tephritic lava flows and dykes) and analcime-free (basaltic to trachytic lava flows and basaltic dykes). The analcime-bearing volcanic rocks have a fine-grained porphyritic texture with clinopyroxene phenocrysts, whereas analcime-free volcanic rocks show a variety of textures including hyalo-microlitic microgranular porphyritic, intersertal, trachytic, fluidal, and glomeroporphyritic. The volcanic rocks also show evidence of mineral-melt disequilibrium textures such as sieved, rounded, and corroded plagioclases, partially melted and dissolved clinopyroxenes and poikilitic texture. Petrochemically, the parental magmas of the volcanic rocks evolved from alkaline to calc-alkaline lava suites and include high-K and shoshonitic compositions. They display enrichments in light rare earth and large ion lithophile elements such as Sr, K, and Rb, as well as depletions in high field strength elements such as Nb, Ta, Zr, and Ti, resembling subduction-related magmas. The analcime-bearing and -free volcanic rocks share similar incompatible element ratios and chondrite-normalised rare rearth element patterns, indicating that they originated from similar sources. They also have relatively low to moderate initial 87Sr/86Sr (0.7042-0.7051), high positive εNd(t) values (+ 0.20 to + 3.32), and depleted mantle Nd model ages (TDM1 = 0.63-0.93 Ga, TDM2 = 0.58-0.84 Ga). The bulk-rock chemical and Sr-Nd isotope features as well as the high Rb/Y and Th/Zr, but low Nb/Zr and Nb/Y ratios, indicate that the volcanic rocks were derived from a lithospheric mantle source that had been metasomatised by slab-derived fluids. Trace element

  12. Waste Minimization Protocols for the Process of Synthesizing Zeolites from South African Coal Fly Ash

    Directory of Open Access Journals (Sweden)

    Leslie F. Petrik

    2013-04-01

    Full Text Available Production of a high value zeolite from fly ash has been shown to be an avenue for the utilization of South African fly ash which presently constitutes a huge disposal problem. The synthesis of zeolites Na-P1 and analcime on a micro-scale has been successful and preliminary investigation shows that scale-up synthesis is promising. However, the post-synthesis supernatant waste generated contains high levels of NaOH that may constitute a secondary disposal problem. A waste minimization protocol was developed to reduce the volume of waste generated with a view to enhancing the feasibility of the scale synthesis. Series of experiments were conducted in 100 mL jacketed batch reactors. Fly ash was reacted with 5 Mol NaOH on a 1:1 mass basis during the aging step, followed by hydrothermal treatment in which ultrapure water was added to the slurry. This study shows that by re-introducing the supernatant waste into the experiments in such a way that it supplies the required reagent (NaOH for the zeolite synthesis, zeolite Na-P1 and analcime can be synthesized. It also shows that the synthesis process can be altered to allow up to 100% re-use of the supernatant waste to yield high value zeolitic products. This study effectively constructed two protocols for the minimization of waste generated during the synthesis of zeolites from South African coal fly ash. This result could be used to establish a basis for legal and environmental aspects involved in the commission of a full-scale plant synthesizing zeolites NaP1 and analcime.

  13. Hydrothermal zeolitisation controlled by host-rock lithofacies in the Periadriatic (Oligocene) Smrekovec submarine composite stratovolcano, Slovenia

    Science.gov (United States)

    Kralj, Polona

    2016-05-01

    Hydrothermal zeolites (laumontite, yugawaralite, analcime, heulandite, clinoptilolite), prehnite and pumpellyite have been recognised in a succession of volcanic, autoclastic, pyroclastic, resedimented volcaniclastic and mixed siliciclastic-volcaniclastic deposits. In cone-building lithofacies association attaining 310 m, the alteration minerals commonly change within a single normally graded depositional unit or alternate in the section on a dm- to m-scale, according to the host-rock lithofacies. Fine-grained deposits rich in juvenile glassy pyroclasts are altered to heulandite and clinoptilolite or analcime, and laumontite widely occurs in coarse-grained host-rocks (lapilli tuff, hyaloclastite breccia, volcaniclastic breccia, hyaloclastites) and fracture systems. In near-vent lithofacies association attaining 420 m, prehnite-laumontite, laumontite-analcime, and laumontite-heulandite-clinoptilolite zones developed as a result of superimposed thermal regime generated by the emplacement of an over 200 m thick sill. The recognised dependence of alteration on porosity, permeability and fracturing of the host-rock is closely related to hydrological conditions in the stratovolcano-hosted hydrothermal system with convective-advective flow regime. After separation of steam and gases from convecting hydrothermal fluids, denser liquids outflowed intermittently, preferentially through steeply inclined (20-30°) high-permeability layers in the stratovolcano edifice. In low-permeability layers the flow was slow and thermal conditions were mainly attained by conduction. Zeolites developed only in coarse- and fine-grained vitroclastic tuffs, presumably by the dissolution of volcanic glass. The interstratified siliciclastic siltstones, tuffites and resedimented deposits with low content of glassy particles are devoid of zeolites and indicate compositional constraint on zeolitisation. Lava flows, cooling in a submarine environment and undergoing disintegration and mingling with

  14. Further description of the petrology of the Topopah Spring member of the paintbrush tuff in drill holes UE25A-1 and USW-G1 and of the lithic-rich tuff in USW-G1, Yucca Mountain, Nevada

    International Nuclear Information System (INIS)

    The Topopah Spring Member of the Paintbrush Tuff and the Lithic-rich tuff and two Tertiary volcanic units that occur in cores from drill holes UE25a-1 and USW-G1 at Yucca Mountain, Nevada. Recently they have been suggested as possibly suitable for the permanent storage of high-level radioactive waste. Earlier petrologic characterization of these units is augmented here. The Topopah Spring Member (approximately 350 m thick) has two compound cooling units. The upper, thinner unit is densely welded to vitrophyric. The lower unit ranges from nonwelded to vitrophyric, and its nonwelded base is extensively zeolitized to clinoptilolite and mordenite. Heulandite occurs as fracture fill in the overlying vitrophyric part, but zeolites are absent above that vitrophyre. Here primary devitrification plus vapor-phase crystallization dominate the mineralogy. Vapor-phase effects are especially prominent between the two vitrophyres in both cores and include numerous large lithophysal cavities throughout most of this moderately to densely welded tuff. The Lithic-rich tuff extends from 1203 to 1506 m in the USW-G1 drill core. It is nonwelded to partly welded but is well indurated due to pervasive intergrowths of authigenic minerals. These phases are analcime, albite, alkali feldspar, sericite, chlorite and quartz. The transition from analcime to secondary albite corresponds to Iijima's zeolite Zone IV boundary, and this boundary appears in USW-G1 at 1326 m. However, analcime remains as a prominent phase through most of the Lithic-rich tuff. Further work is necessary to assess the suitability of either of these horizons for a waste repository. In the Topopah Spring Member, both mechanical and hydrologic properties of thick lithophysal zone must be studied, as well as the complete sequence of fracture fill. For both units, zeolite and clay mineral stabilities need to be investigated

  15. Geological, mineralogical and geochemical characteristics of zeolite deposits associated with borates in the Bigadiç, Emet and Kirka Neogene lacustrine basins, western Turkey

    Science.gov (United States)

    Gündogdu, M. N.; Yalçin, H.; Temel, A.; Clauer, N.

    1996-09-01

    The Bigadiç, Emet and Kirka lacustrine basins of western Turkey may be considered as Tibet-type graben structures that were developed during the Miocene within the Izmir-Ankara suture zone complex. The volcanic-sedimentary successions of these basins are made up of mudstone, carbonate (limestone and dolomite) and detrital rocks, and also of crystal or vitric tuffs about 135 to 200 m thick. The Degirmenli (Bigadiç), Emirler (Bigadiç) Köpenez (Emet) and Karaören (Kirka) tuffs constituting the zeolite deposits are situated beneath four borate deposits (colemanite, ulexite, borax). The most abundant diagenetic silicate minerals are K- and Ca-clinoptilolites in the zeolite deposits, and Li-rich trioctahedral smectites (stevensite, saponite and hectorite) and K-feldspar in the borate deposits. In the Degirmenli, Emirler, Köpenez and Karaören deposits, the following diagenetic facies were developed from rhyolitic glasses rich in K and poor in Na: (glass+smectite), (K-clinoptilolite+opal-CT), (Ca-clinoptilolite+K-feldspar±analcime± quartz) and (K-feldspar+analcime+quartz). K-feldspar which is also rarely associated with phillipsite (Karaören) and heulandite (Degirmenli and Karaören), succeeds clinoptilolite and precedes analcime in these diagenetic facies where dioctahedral smectites, opal-CT and quartz are the latest minerals. No diagenetic transformations exist between clinoptilolite, K-feldspar and analcime that were formed directly from glass. The lateral facies distributions resulted from the differences in salinity and pH of pore water trapped during deposition of the tuffs, but vertical distributions in vitric tuffs seem to have been controlled by the glass/liquid ratio of the reacting system and the permeability or diffusion rate of alkali elements. The Bigadiç, Emet and Kirka zeolite deposits which were formed in saline basins rich in Ca and Mg ions, show similar chemical changes, i.e. loss of alkalis and gain in alkaline-earth elements that have taken

  16. Zeolite mineralogy of the Cayo formation in Guayaquil, Ecuador

    OpenAIRE

    Machiels, L.; Morante Carballo, Fernando Enrique; Snellings, R.; Calvo Pérez, Benjamín; Canoira López, Laureano; Paredes Bartolomé, Carlos; Elsen, J.

    2008-01-01

    This work shows the presence of zeolites in the Cretaceous Cayo formation in Coastal Ecuador. In the area of Guayaquil the Cayo formation consist of marine pyroclastic flow deposits, associated fallout tuffs and epiclastic rocks. The main zeolites are Ca-heulandite (mean Si/Al: 3.30) and Ca-clinoptilolite (mean Si/Al: 4.35). Less common are laumontite, mordenite and analcime. Zeolites compose 10–60% of the rocks. The deposit is of great importance for Ecuador, considering its enormous zeoliti...

  17. Zeolites of the Valle Central of Costa Rica and its outskirts

    International Nuclear Information System (INIS)

    19 different species of zeolites have been found in 25 outcrops in the Valle Central of Costa Rica and in the Siquirres region. All the zeolites are secondary minerals and crystallized in little veins and vesicles of the basalts and pyroclastics rocks of the La Cruz and Grifo Alto formations, belonging to the Aguacate Group and the alkaline igneous rocks of Guayacan. The most frequent species of zeolites are stibnite, chabasite, laumontite, mesolite/mordenite, thomsonite, and analcime. Natrolite only was found near to Siquirres. (Author)

  18. Clay mineralogy of the Boda Claystone Formation (Mecsek Mts., SW Hungary

    Directory of Open Access Journals (Sweden)

    Németh Tibor

    2016-04-01

    Full Text Available Boda Claystone Formation (BCF is the host rock of the planned site for high level nuclear waste repository inHungary. Samples representing the dominant rock types of BCF were studied: albitic claystone, claystone with high illite content, and analcime bearing claystone. Clay minerals in these three rock types were characterized by Xray powder diffraction (XRD, transmission electron microscopy (TEM and thermal analysis (DTA-TG, and the results were discussed from the point of view of the radionuclide sorption properties being studied in the future. Mineral compositions of bulk BCF samples vary in wide ranges. In the albitic sample, besides the dominant illite, few percent of chlorite represents the layer silicates in the clay fraction. Illite is the dominating phase in the illitic sample, with a few percent of chlorite. HRTEM study revealed that the thickness of illite particles rarely reaches 10 layers, usually are of 5-6 TOT layer thick. Illite crystals are generally thicker in the albitic sample than in the illitic one. The significant difference between the clay mineral characterisitics of the analcimous and the other two samples is that the former contains regularly interstratified chlorite/smectite beside the dominant illite.

  19. Distribution and chemistry of fracture-lining zeolites at Yucca Mountain, Nevada

    International Nuclear Information System (INIS)

    Yucca Mountain, a > 1.5-km thick sequence of tuffs and subordinate lavas in southwest Nevada, is being investigated as a potential high-level nuclear waste repository site. Fracture-lining minerals are possible sources of information on past transport within the tuffs, and they may act as natural barriers to radionuclide migration along the fractures. Cores from several drill holes were examined to determine the distribution and chemistry of zeolite minerals in fractures. Fracture-lining minerals in the Paintbrush Tuff are highly variable in distribution, both vertically and laterally across the mountain, with mordenite, heulandite, and stellerite widespread in fractures even though the tuff matrix is generally devitrified and not zeolitic. Where heulandite occurs as both tabular and prismatic crystals in the same fracture, the two morphologies have different compositions, suggesting multiple episodes of zeolite formation within the fractures. In contrast to the Paintbrush Tuff, fractures in the Calico Hills Formation and the Crater Flat Tuff generally contain abundant clinoptilolite and mordenite only where the matrix is zeolitic, although mordenite does occur as fracture linings in some devitrified intervals of the Crater Flat Tuff as well. The fracture-lining zeolites correlate with the degree of alteration of the zeolitic tuffs, with clinoptilolite plus mordenite in tuffs containing clinoptilolite, and analcime in fractures limited to tuff intervals containing analcime. These data suggest that fracture-lining zeolite formation may have been coincident with the original alteration of the tuffs

  20. Morphology and origin of dolomite in paleosols and lacustrine sequences. Examples from the Miocene of the Madrid Basin

    Science.gov (United States)

    Casado, Ana I.; Alonso-Zarza, Ana M.; La Iglesia, Ángel

    2014-10-01

    The northern Madrid Basin contains paleosols and lacustrine sequences composed of ordered dolomite. Smectite-rich mudstones with analcime deposited in distal alluvial fans affected by pedogenic processes. Mudstones contain dolomite and silica laminae interpreted as mineralized root-mats. Dolostones with prismatic structure constitute Stage III dolocretes. Homogeneous lacustrine dolomudstones show some features indicative of subaerial exposure. Dolomite textures include: microcrystalline dolomite, coarse crystalline mosaics located in root cavities, dolomite dumbbells and dolomite spheroids replacing clays, dolomudstones or opal. Mol values of MgCO3 of dolomites vary between 47.67% and 53.34% mol. δ18O values range between - 3.65 and - 5.51‰ VPDB. δ13C values range between - 7.19 and - 8.38‰ VPDB. Dolomicrite formed in alkaline lakes by direct precipitation and replacement of clays in soils. The rhizosphere was favorable for dolomite mosaic and dumbbells formation. Spheroidal dolomite replaced clays and opal under early phreatic diagenesis. Trioctahedral smectites, silica and analcime indicate that these pedogenic and lacustrine environments were alkaline. Smectites and/or carboxyl groups acted as a catalyst favoring the incorporation of Mg into dolomite. In these non-saline settings the kinetic barriers for dolomite precipitation lowered by high pH and Mg enrichment. Ordered dolomite formation occurred under biogenic and abiogenic conditions, during sedimentation, pedogenesis and early diagenesis.

  1. Synthesis of zeolitic materials from volcanic ash in presence and absence of cetyltrimethylammonium bromide

    Energy Technology Data Exchange (ETDEWEB)

    Sanhueza N, V. M.; Bennun T, L. D., E-mail: vsanhuez@udec.cl [Universidad de Concepcion, Facultad de Ciencias Quimicas, Edmundo Larenas 129, Region del Biobio (Chile)

    2015-07-01

    Zeolitic materials as Na-phillipsite, Na-K-phillipsite-like zeolites and the mixtures of zeolites (phillipsite+analcime and phillipsite+chabazite+analcime) were synthesized from volcanic ash, either in presence and absence of cetiltrimetilamonium bromide (CTAB). The ash sample used in the laboratory experiments contains 75.36% SiO{sub 2} and 14.11% Al{sub 2}O{sub 3}, abundances. The reaction time as well as the influence of CTAB were studied in the zeolitic materials crystallization. The experiments were carried out under hydrothermal conditions, autogenic pressure and temperature of 150 grades C, as well as reaction time from 8 to 116 h. Products from this hydrothermal treatment were identified by X-ray diffraction (XRD) and characterized by scanning electron microscopy-energy dispersive X-ray spectroscopy (Sem-EDS). Of the zeolitic materials obtained the Na-K-phillipsite-like zeolite was found to be the most effective for the retention of cations Pb{sup 2+}, Zn{sup 2+} and Ba{sup 2+}. (Author)

  2. Synthesis of zeolitic materials from volcanic ash in presence and absence of cetyltrimethylammonium bromide

    International Nuclear Information System (INIS)

    Zeolitic materials as Na-phillipsite, Na-K-phillipsite-like zeolites and the mixtures of zeolites (phillipsite+analcime and phillipsite+chabazite+analcime) were synthesized from volcanic ash, either in presence and absence of cetiltrimetilamonium bromide (CTAB). The ash sample used in the laboratory experiments contains 75.36% SiO2 and 14.11% Al2O3, abundances. The reaction time as well as the influence of CTAB were studied in the zeolitic materials crystallization. The experiments were carried out under hydrothermal conditions, autogenic pressure and temperature of 150 grades C, as well as reaction time from 8 to 116 h. Products from this hydrothermal treatment were identified by X-ray diffraction (XRD) and characterized by scanning electron microscopy-energy dispersive X-ray spectroscopy (Sem-EDS). Of the zeolitic materials obtained the Na-K-phillipsite-like zeolite was found to be the most effective for the retention of cations Pb2+, Zn2+ and Ba2+. (Author)

  3. Diagénesis y arcillas intersticiales en las unidades neopaleozoicas del Grupo Paganzo-La Rioja Diagenesis and intersticial clays of the late Paleozoic Paganzo Group - La Rioja

    Directory of Open Access Journals (Sweden)

    R.R. Andreis

    2006-09-01

    Full Text Available En esta contribución se describen los principales procesos diagenéticos vinculados a las arcillas que ocurren en las areniscas de las unidades Neopaleozoicas del Grupo Paganzo. Se incluyen minerales de la arcillas en las wackes y en los poros de areniscas (caolinita, illita, clorita, y minerales interestratificados, procesos de neoformación (caolinita a dickita y procesos de cementación (hematita, calcita. Las tobas y tobas pisolíticas con chalazolitas contienen vitroclastos planares, curviplanares y ramificados y pumicitas vesiculares y están alterados a esmectita y analcima (Formaciones Patquía y La Colina. En la Formación La Antigua, los vitroclastos están alterados en caolinita y analcima.In this paper the most important diagenetic clay-related processes that take place in the sandstones from the Neopaleozoic units of the Paganzo Group are described. They include both clay minerals in the wackes and in the pores of clean sandstones (caolinite, illite, chlorite, interestratified clay minerals, processes of neoformation (caolinite to dickite and of cementation (hematite, calcite. The tuffs and pisolithic tuffs with chalazolites in the Patquía and La Colina formations have planar, curviplanar and branched vitroclasts and vesicular pumites and they are also altered into smectite and analcime, while the tuffs of La Antigua Formation, are altered into kaolinite and analcime.

  4. Significant mineral variations in the Lower Karoo deposits of the Mid-Zambezi Basin, Zimbabwe, and their palaeoenvironmental implications

    International Nuclear Information System (INIS)

    Mineralogical composition of Lower Karoo deposits from the Mid-Zimbabwe Basin, Zimbabwe, have been established by means of X-ray diffractometry to evaluate mineralogical variables as possible palaeoenvironment indicators. Mineral variations are stratigraphically controlled. Dwyka tillites are composed of quartz, K-feldspar and plagioclase. Varvites contain additional calcite. The clay fraction is dominated by kaolinite in the northwestern part of the study area while in the southwest only subordinate proportions of kaolinite occur associated with approximately equal amounts of mica, chlorite, smectite, and interstratifications. The overlying Ecca sediments are characterized by a high kaolinite content, traces of K-feldspar, mica and occasional pyrite. In mudstones of the uppermost Ecca, the kaolonite proportion decreases in favour of mica and chlorite. The mineral composition of Beaufort mudstones differs significantly with considerable amounts of plagioclase and a more than sporadic presence of analcime which is restricted to this stratigraphic unit. The clay fraction is dominated by either kaolinite, mica, or smectite. Within the geotectonical setting discussed by this paper the kaolinite dominance in Ecca sediments corresponds well with freshwater depositional conditions deduced from sedimentological and palaeontological evidence. However, the abundance of 2:1 phyllosilicates and especially analcime prevalence in the Beaufort section indicates an alkaline palaeoenvironment. 10 figs., 29 refs

  5. ThermoChimie database developments in the framework of cement/clay interactions

    International Nuclear Information System (INIS)

    Highlights: • We present a selection of thermodynamic properties for cement minerals, zeolites and clay minerals. • The work takes place within the framework of the geological disposal of nuclear wastes. • Consistency is checked by establishing predominance area diagrams. • A specific focus is proposed for zeolites, with examples of analcime and mordenite. - Abstract: We present here the global results of an eight-year project, where we attempted to complete the ThermoChimie database for cement minerals, zeolites and clay minerals. This work reports the methodology adopted to ensure the consistency between the three groups of minerals. Our first step concerns the relations between the three groups of minerals from field observations and experimental results gathered from the literature. A summary of the selection process is then given for clay and cement minerals and a specific focus is proposed for zeolites, with examples of analcime and mordenite. The global consistency of the selection is investigated with respect to the main chemical tendencies found for cement/clay interactions, especially considering the “alkalinity” of the minerals. Consistency is checked by establishing predominance diagrams in the chemical sub-systems of interest for the three groups of minerals, then comparing the phase relations with respect to experimental results or field observations. The methodology is illustrated using the case of gismondine and zeolite P(Ca)

  6. A study on long term stability of bentonite. The preliminary study on the bentonite stability in the groundwater influenced by cementitious material

    International Nuclear Information System (INIS)

    In the geological disposal concept of radioactive wastes, a kind of clay with sorption ability and low permeability, called bentonite, is envisaged as an engineered barrier system in the geological repository. Also, the cementitious material is envisaged as the backfill material in the vaults and the structure material of the vaults. The groundwater in contact with the cementitious material will promote hyperalkaline conditions in the repository environment and these conditions will affect the performance of the bentonite. Therefore, it is necessary to investigate the interaction between the cementitious material and the bentonite for the evaluation of long term stability of the disposal system. In this study, for the identification and the investigation of the secondary minerals, the batch immersion experiments of the powder bentonite were carried out using synthetic cement leachates (pH=7, 12.5, 14) at 200degC. As the results, it was confirmed that Na as exchangeable cations in the bentonite can exchange relatively easily with Ca in the solution from the experiment results. And the ratio of cation exchange was estimated to be about 25% based on the amount of exchangeable cations Ca2+ between layers. Furthermore, it was concretely shown that the generation of analcime might be affected by the Na concentration from results of the solution analyses and a stability analysis of analcime using the chemical equilibrium model, in addition to the pH in the solution. (author)

  7. Diagenesis of Oligocene continental sandstones in salt-walled mini-basins-Sivas Basin, Turkey

    Science.gov (United States)

    Pichat, Alexandre; Hoareau, Guilhem; Callot, Jean-Paul; Ringenbach, Jean-Claude

    2016-06-01

    The recent discovery of Oligo-Miocene salt-walled continental mini-basins in the Sivas Basin (central Anatolia, Turkey) provides the opportunity to unravel the influence of halokinesis on the diagenesis of continental mini-basin infilling. In this study, petrographic and geochemical analyses are used to define the diagenetic sequences recorded by two mini-basins filled mainly by fluvial clastic sediments of the upper Oligocene Karayün Formation. The initial diagenetic features are those commonly encountered in arid to semi-arid continental environments, i.e. clay infiltration, hematite precipitation and vadose calcite cement. Other early cements were strongly controlled by sandstone detrital composition in the presence of saline/alkaline pore water. In feldspathic litharenites and lithic arkoses, near-surface alterations were characterized by the precipitation of analcime (up to 10%), albite and quartz overgrowths (cementation (up to 30%) during shallow burial diagenesis which prevented further mesogenetic alteration phenomena such as compaction. In feldsarenites, early diagenesis differs by (i) the absence of analcime, (ii) better developed albite cements, (iii) thin smectite-illite coatings forming pore linings and (iv) patchy calcite cementation (cement allowed mesogenetic alterations to occur, such as late quartz overgrowths, albitization of feldspar grains and chemical compaction. All these phases are responsible for the low porosity of feldsarenites (cement in feldspathic litharenites and lithic arkoses is related to a greater proportion of detrital limestone in these sandstones. Early precipitation of analcime, albite, smectite-illite and quartz was likely triggered by the alteration of reactive grains by near-surface saline/alkaline brines originating from the dissolution of adjacent diapiric structures. Mini-basin confinement resulting from halokinesis was probably an important factor influencing surface and subsurface saline/alkaline fluid flow and

  8. Diagramas de eslabilidad de zeolitas. I. Zeolitas en ambientes confinados alcalinos

    Directory of Open Access Journals (Sweden)

    La Iglesia, A.

    1989-12-01

    Full Text Available The stability fieds of zeolites in saline alkaline-lake deposits has been studied. Thermodynamical equilibriums were calculed by ussing a method of stimating the Gibbs free energies of formation of zeolites. We have studied the following stability fields: - Diagram c1inoptilolite-erionite-phillipsite.- Diagram analcime-clinoptilolite-chabazite-erionite-mordenite-phillipsite.- Diagram K-feldspar-zeolites in saline alkaline-lake deposits.The obtained stability diagrams show the influence of silica activity, water activity and alkaline ions activity on equilibrium relationship between analcime and alkalic silicic zeolites, and or feldspar and zeolites. pH influence on the solubility zeolites has been also studied. These results show, at pH below 10, that the most silicic zeolites (clinoptilolite and mordenite are more stable than low silicic ones (analcime and chabazite. However, at pH above 10, the low silicic zeolites are the most stable phases.Se estudia la estabilidad de las zeolitas que aparecen en ambientes confinados salinos. Los cálculos de equilibrio se realizan usando valores de energía libre de Gibbs estimados teóricamente. En este artículo se presentan los siguientes diagramas de estabilidad:- Diagrama clinoptiloita-erionita-phillipsita.- Diagrama aoalcima-clinoptilolita-chabazita-eriooita-mordenita-phillipsita.- Diagrama feldespato potásico-zeolitas depósitos salinos.Los diagramas calculados ponen de manifiesto la influencia de las actividades de los iones alcalinos, alcalinotérreos, agua y sílice en el equilibrio entre las distintas zeolitas y entre estas y el feldespato potásico. Se estudia también la influencia del pH en la solubilidad de las zeolitas. Los resultados obtenidos demuestran que las zeolitas muy silícicas (clinoptilolita y mordenita son las más estables a pH inferiores a 10. Por el contrario, las zeolitas de bajo contenido en sílice (analcima y chabazita son las más estables a pH superiores a 10.

  9. Inorganic Corrosion-Inhibitive Pigments for High-Temperature Alkali-activated Well Casing Foam Cement

    Energy Technology Data Exchange (ETDEWEB)

    Sugama, T. [Brookhaven National Lab. (BNL), Upton, NY (United States); Pyatina, T. [Brookhaven National Lab. (BNL), Upton, NY (United States)

    2014-11-14

    This study evaluates inorganic pigments for improving carbon steel (CS) brine-corrosion protection by the sodium metasilicate-activated calcium aluminate cement/Fly Ash blend at 300°C. Calcium borosilicate (CBS) and zinc phosphate, significantly improved CS corrosion-protection by decreasing cement’s permeability for corrosive ions and inhibiting anodic corrosion. An amorphous Na2O-Al2O3-SiO2-H2O phase tightly attached to CS surface formed at 300oC in CBS-modified cement pore solution. The corrosion rate of the CS covered with this phase was nearly 4-fold lower than in the case of nonmodified cement pore solution where the major phase formed on the surface of CS was crystalline analcime.

  10. Inorganic Corrosion-Inhibitive Pigments for High-Temperature Alkali-activated Well Casing Foam Cement

    Energy Technology Data Exchange (ETDEWEB)

    Sugama, T. [Brookhaven National Lab. (BNL), Upton, NY (United States); Pyatina, T. [Brookhaven National Lab. (BNL), Upton, NY (United States)

    2014-11-01

    This study evaluates inorganic pigments for improving carbon steel (CS) brine-corrosion protection by the sodium metasilicate-activated calcium aluminate cement/Fly Ash blend at 300°C. Calcium borosilicate (CBS) and zinc phosphate, significantly improved CS corrosion-protection by decreasing cement’s permeability for corrosive ions and inhibiting anodic corrosion. An amorphous Na2O-Al2O3-SiO2-H2O phase tightly attached to CS surface formed at 300oC in CBS-modified cement pore solution. The corrosion rate of the CS covered with this phase was nearly 4-fold lower than in the case of nonmodified cement pore solution where the major phase formed on the surface of CS was crystalline analcime.

  11. Dacite – siltstone peperite from Trlično at Rogatec, Eastern Slovenia

    Directory of Open Access Journals (Sweden)

    Polona Kralj

    2006-06-01

    Full Text Available Dacitic glassy lava flow at Trlično is surrounded by a dacite – siltstone peperite and peperitic breccia that underwent alteration, recognised in two, only a few metres thick zones. In the higher-temperature alteration zone, albite extensively replaces volcanic glass and primary plagioclases. The siltstone components are altered to microcrystalline quartz, iron oxides and interlayered illite/smectite clay minerals. This zone developed upon thermalmetamorphosis related to the transfer of heat from the cooling lava. In the lower temperature alteration zone, analcime occurs as the replacement of volcanic glass and pore- and fissure-filling, while the primary plagioclases and poorly lithified siltstone remained fairly unchanged. This zone developed under hydrothermal conditions related to the heating, circulation and reactions of pore waters in the sediment surrounding the lava flow.

  12. Elaboration of y-fanjasite catalysts containing radioactive elements such as uranyl ion in order to obtain aromatic solvents and heavy amines

    International Nuclear Information System (INIS)

    The present work has shown the possibility of ammonia alkylation by n-octanol-l in gaseous phase, in presence of zeolitic catalysts. These catalysts are Y faujasitic types being used in waste water demineralization containing radioactive elements such as uranyl ion. This ion gives to the Y faujasite similar activity and selectivity as those of catalysts containing rare earths or transition metals. Toluene disproportionation has permitted to test beforehand catalysts destined to ammonia alkylation and to compare their mechanism. We have also proved the possibility to produce heavy amines such as tertiary amines which are used as uranium extractant agent. Some zeolites such as ZSM-5, beta, X, A, analcime, HS and Y faujasite type are prepared by hydrothermal synthesis method and characterized by some analysis techniques

  13. From anorthite to vesuvianite: an excursion through the minerals first discovered in Italy

    Institute of Scientific and Technical Information of China (English)

    GiovanniFerraris; MarcoCiriotti

    2003-01-01

    With regard to the number of mineral species first dis-covered in a particular country, Italy ranks fourth, being preceded only by USA, Russia and Germany. Important rock-forming minerals like analcime, anorthite, anortho-clase, antigorite, celadonite, diopside, dolomite,forsterite, humite, leucite, lime, lizardite, magnesiochlo-ritoid, magnesite, nepheline, and sepiolite are among the 240 species first discovered in Italy. Other significant first Italian findings are some important index mineralsof the UHP metamorphism (ellenbergerite, phosphoel-lenbergerite, magnesiodumortierite, and magnesiostau-rolite; second occurrence of coesite) which were discov-ered in the well-known and first reported UHP outcrop of the Dora-Màira massif Italy is also the native land of about 30 zeolites and of the two most abundant modern species: balangeroite and carlosturanite, which are rock-forming asbestos-like minerals of serpentinites in the western Alps.

  14. Preliminary stratigraphic and petrologic characterization of core samples from USW-G1, Yucca Mountain, Nevada

    International Nuclear Information System (INIS)

    Tuffs of the Nevada Test Site are currently under investigation to determine their potential for long-term storage of radioactive waste. As part of this program, hole USW-G1 was drilled to a depth of 6000 ft below the surface, in the central part of the Yucca Mountain area, Nevada Test Site, Nevada. Petrographic study of the USW-G1 core is presented in this report and shows the tuffs (which generally were variably welded ash flows) are partly recrystallized to a variety of secondary minerals. The important alteration products are zeolites (heulandite, clinoptilolite, mordenite and analcime), smectite clays with minor interstratified illite, albite, micas, potassium feldspar, and various forms of silica. Iijima's zeolite zones I through IV of burial metamorphism can be recognized in the core. Zeolites are first observed at about the 1300-ft depth, and the high-temperature boundary of zeolite stability in this core occurs at about 4350 ft. Analcime persists, either metastably or as a retrograde mineral, deeper in the core. The oxidation state of Fe-Ti oxide minerals, through most of the core, increases as the degree of welding decreases, but towards the bottom of the hole, reducing conditions generally prevail. Four stratigraphic units transected by the core may be potentially favorable sites for a waste repository. These four units, in order of increasing depth in the core, are (1) the lower cooling unit of the Topopah Spring Member, (2) cooling unit II of the Bullfrog Member, (3) the upper part of the Tram tuff, and (4) the Lithic-rich tuff

  15. Experimental study on long-term stability of bentonite. Influence of hyperalkaline pore water generated by the chemical reaction of cementitious material and saline groundwater

    International Nuclear Information System (INIS)

    The engineered barrier system (EBS) in the geological disposal of TRU waste is composed of bentonite and cementitious materials. The montmorillonite component of bentonite is, however, not chemically compatible with the high pH leachates derived from cementitious materials and may alter to a more stable secondary mineral assemblage. Previous research for TRU waste disposal has focused on the alteration behavior of bentonite in leachates from cementitious materials exposed to fresh groundwater. If the EBS is located in the coastal region, then the leachates will instead be derived from the interaction of cementitious materials and saline groundwater. This has important implications for the alteration of bentonite because the likely difference in the chemical composition of the leachate will influence the dissolution rate of montmorillonite and the composition of the secondary mineral assemblage. At present, these processes are not well understood. The focus of the present study was to examine the alteration of bentonite in high pH saline groundwaters. Two solutions were used in batch immersion experiments of bentonite. The first solution was prepared using a mixture of NaOH and NaCl (NN), and the second solution was prepared using synthetic Region 1 water (high K and Na content) and synthetic seawater (SR). Analysis showed that bentonite altered to analcime in the NN solution and to analcime and phillipsite-K in the SR solution. Moreover, the generation of calcium silicate hydrate and calcium aluminosilicate hydrate were extrapolated in the SR solution based on the concentrations of dissolved species. These alteration products were in accord with Oda et al.(2005), who summarized the possible relationships between the secondary mineral assemblage of bentonite under high pH conditions and the influence of solution composition. (author)

  16. Evidence for low-grade metamorphism, hydrothermal alteration, and diagenesis on mars from phyllosilicate mineral assemblages

    Science.gov (United States)

    Ehlmann, B.L.; Mustard, J.F.; Clark, R.N.; Swayze, G.A.; Murchie, S.L.

    2011-01-01

    The enhanced spatial and spectral resolution provided by the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) on the Mars Reconnaissance Orbiter (MRO) has led to the discovery of numerous hydrated silicate minerals on Mars, particularly in the ancient, cratered crust comprising the southern highlands. Phases recently identified using visible/near-infrared spectra include: smectite, chlorite, prehnite, high-charge phyllosilicates (illite or muscovite), the zeolite analcime, opaline silica, and serpentine. Some mineral assemblages represent the products of aqueous alteration at elevated temperatures. Geologic occurrences of these mineral assemblages are described using examples from west of the Isidis basin near the Nili Fossae and with reference to differences in implied temperature, fluid composition, and starting materials during alteration. The alteration minerals are not distributed homogeneously. Rather, certain craters host distinctive alteration assemblages: (1) prehnite-chlorite-silica, (2) analcime-silica-Fe,Mg-smectite-chlorite, (3) chlorite-illite (muscovite), and (4) serpentine, which furthermore has been found in bedrock units. These assemblages contrast with the prevalence of solely Fe,Mg-smectites in most phyllosilicate-bearing terrains on Mars, and they represent materials altered at depth then exposed by cratering. Of the minerals found to date, prehnite provides the clearest evidence for subsurface, hydrothermal/metamorphic alteration, as it forms only under highly restricted conditions (T = 200 400??C). Multiple mechanisms exist for forming the other individual minerals; however, the most likely formation mechanisms for the characteristic mineralogic assemblages observed are, for (1) and (2), low- grade metamorphism or hydrothermal (400??C has not been found.

  17. Spatial and stratigraphic distribution of water in oil shale of the Green River Formation using Fischer Assay, Piceance Basin, northwestern Colorado

    Science.gov (United States)

    Johnson, Ronald C.; Mercier, Tracey J.; Brownfield, Michael E.

    2014-01-01

    The spatial and stratigraphic distribution of water in oil shale of the Eocene Green River Formation in the Piceance Basin of northwestern Colorado was studied in detail using some 321,000 Fischer assay analyses in the U.S. Geological Survey oil-shale database. The oil-shale section was subdivided into 17 roughly time-stratigraphic intervals, and the distribution of water in each interval was assessed separately. This study was conducted in part to determine whether water produced during retorting of oil shale could provide a significant amount of the water needed for an oil-shale industry. Recent estimates of water requirements vary from 1 to 10 barrels of water per barrel of oil produced, depending on the type of retort process used. Sources of water in Green River oil shale include (1) free water within clay minerals; (2) water from the hydrated minerals nahcolite (NaHCO3), dawsonite (NaAl(OH)2CO3), and analcime (NaAlSi2O6.H20); and (3) minor water produced from the breakdown of organic matter in oil shale during retorting. The amounts represented by each of these sources vary both stratigraphically and areally within the basin. Clay is the most important source of water in the lower part of the oil-shale interval and in many basin-margin areas. Nahcolite and dawsonite are the dominant sources of water in the oil-shale and saline-mineral depocenter, and analcime is important in the upper part of the formation. Organic matter does not appear to be a major source of water. The ratio of water to oil generated with retorting is significantly less than 1:1 for most areas of the basin and for most stratigraphic intervals; thus water within oil shale can provide only a fraction of the water needed for an oil-shale industry.

  18. Clay mineralogy of the Boda Claystone Formation (Mecsek Mts., SW Hungary)

    Science.gov (United States)

    Németh, Tibor; Máthé, Zoltán; Pekker, Péter; Dódony, István; Kovács-Kis, Viktória; Sipos, Péter; Cora, Ildikó; Kovács, Ivett

    2016-04-01

    Boda Claystone Formation (BCF) is the host rock of the planned site for high level nuclear waste repository inHungary. Samples representing the dominant rock types of BCF were studied: albitic claystone, claystone with high illite content, and analcime bearing claystone. Clay minerals in these three rock types were characterized by Xray powder diffraction (XRD), transmission electron microscopy (TEM) and thermal analysis (DTA-TG), and the results were discussed from the point of view of the radionuclide sorption properties being studied in the future. Mineral compositions of bulk BCF samples vary in wide ranges. In the albitic sample, besides the dominant illite, few percent of chlorite represents the layer silicates in the clay fraction. Illite is the dominating phase in the illitic sample, with a few percent of chlorite. HRTEM study revealed that the thickness of illite particles rarely reaches 10 layers, usually are of 5-6 TOT layer thick. Illite crystals are generally thicker in the albitic sample than in the illitic one. The significant difference between the clay mineral characterisitics of the analcimous and the other two samples is that the former contains regularly interstratified chlorite/smectite beside the dominant illite. Based on the structural and chemical data two illite type minerals are present in the BCF samples: 1M polytype containing octahedral Fe and Mg besides Al, 2M polytype illite generally is free of Fe andMg. Close association of very thin illite plates and nanosized hematite crystals is typical textural feature for BCF. The goal of this study is to provide solid mineralogical basis for further studies focusing on radionuclide sorption properties.

  19. Preliminary stratigraphic and petrologic characterization of core samples from USW-G1, Yucca Mountain, Nevada

    Energy Technology Data Exchange (ETDEWEB)

    Waters, A.C.; Carroll, P.R. (eds.)

    1981-11-01

    Tuffs of the Nevada Test Site are currently under investigation to determine their potential for long-term storage of radioactive waste. As part of this program, hole USW-G1 was drilled to a depth of 6000 ft below the surface, in the central part of the Yucca Mountain area, Nevada Test Site, Nevada. Petrographic study of the USW-G1 core is presented in this report and shows the tuffs (which generally were variably welded ash flows) are partly recrystallized to a variety of secondary minerals. The important alteration products are zeolites (heulandite, clinoptilolite, mordenite and analcime), smectite clays with minor interstratified illite, albite, micas, potassium feldspar, and various forms of silica. Iijima`s zeolite zones I through IV of burial metamorphism can be recognized in the core. Zeolites are first observed at about the 1300-ft depth, and the high-temperature boundary of zeolite stability in this core occurs at about 4350 ft. Analcime persists, either metastably or as a retrograde mineral, deeper in the core. The oxidation state of Fe-Ti oxide minerals, through most of the core, increases as the degree of welding decreases, but towards the bottom of the hole, reducing conditions generally prevail. Four stratigraphic units transected by the core may be potentially favorable sites for a waste repository. These four units, in order of increasing depth in the core, are (1) the lower cooling unit of the Topopah Spring Member, (2) cooling unit II of the Bullfrog Member, (3) the upper part of the Tram tuff, and (4) the Lithic-rich tuff.

  20. Preparation for kinetic measurements on the silicates of the Yucca Mountain potential repository. [Final report], June 15, 1993--September 30, 1993

    International Nuclear Information System (INIS)

    Part 1, ''The Preparation of Clinoptilolite, Mordenite and Analcime,'' summarized progress made during the contract period on preparing Na-end member clinoptilolite, mordenite, and analcime. The objective is to use the prepared zeolites to determine rates of dissolution and precipitation in laboratory flow-through systems in both this lab to 350 C and by the geochemists at Yale University to about 80 C. Because clinoptilolite represents the most complicated phase of these three zeolites and it is most abundant at Yucca Mountain, the authors have concentrated most of their efforts on its preparation. They have collected, high-concentration natural clinoptilolite samples. A hindered settling technique that takes advantage of the relatively low specific gravity of clinoptilolite coupled with ultrasonic cleaning in deionized water has been employed. This material is now a mixed Na-K zeolite which must then be converted to the pure Na-end member composition. In Part 2, ''Draft Manuscript on the Heterogeneous Kinetics of Cristobalite,'' experiments on the rates of reactions of dissolution and precipitation of cristobalite were carried at 150--300 C. Results show that cristobalite may precipitate from hydrothermal solution if the concentration of Si(OH)4 exceeds that at quartz saturation and is less than that of amorphous silica saturation and if there are cristobalite nuclei present. Such nuclei may occur where there has been devitrification of volcanic glasses, for example. Cristobalite has refused to crystallize in the absence of such nuclei. Steady state concentrations were reached experimentally after starting at 150 degree with initially supersaturated solutions and at 200 C starting with either supersaturated or undersaturated solutions. From the steady state conditions, equilibrium constants can be derived

  1. Estimación de propiedades termodinámicas de silicatos. Construcción de diagramas de actividad de zeolitas

    Directory of Open Access Journals (Sweden)

    La Iglesia, A.

    1995-12-01

    Full Text Available In this paper we analyze the present methods of estimation of the thermodynamic properties of silicates with special emphasis on the free energy and enthalpy of zeolites. These data are not available in the literature, as these phases are chemically complexo The obtained values allow us to build the 10 following thermodynamic equilibrium diagrams: solubility of laumontite, chabazite, analcime, volcanic glass, zeolite A and zeolite X, and stability diagrams of chabazite-analcime-phillipsite-volcanic glass, clinoptilolite-phillipsite-erionite, prehnite-laumontite-heulandite, and kaolinite-metakaolinhidrosodalite-zeolite A. These diagrams can be useful to understand the genesis of these minerals and the processes that allow their formation in the laboratory.En este artículo se pasa revista a los métodos actuales de estimación de propiedades termodinámicas de silicatos, haciendo especial énfasis a los dedicados a la estimación de la energía libre de formación y de la entalpía de zeolitas, datos poco disponibles en la bibliografía debido a la complejidad química de estas fases. Los valores obtenidos han permitido construir los 10 diagramas de equilibrio termodinámico siguientes: diagramas de solubilidad de laumontita, chabazita, analcima, vidrio volcánico, zeolita A y zeolita X y los de estabilidad de chabazita-analcima-philipsitavidrio volcánico, clinoptilolita-philipsita-erionita, prehnita-laumontita-heulandita y caolinita-metacaolinita-hidrosodalita-zeolita A. Estos diagramas pueden explicar la génesis de los minerales o los procesos que dan lugar a su síntesis en el laboratorio.

  2. Alkali element enrichments on the BABBs at the IODP Expedition 333 Site C0012 in the northern Shikoku Basin

    Science.gov (United States)

    Haraguchi, S.; Nakamura, K.; Fujinaga, K.

    2015-12-01

    The Shikoku Basin is a back arc basin located westside of the Izu-Ogasawara (Bonin) arc, spreading was from 25 to 15 Ma. The drilling of the DSDP, ODP and IODP recovered the backarc basin basalt (BABB) of the Shikoku Basin. Site C0012, south of the Kii Peninsula, was operated during the IODP Exp 333, and BABB was recovered 100m thickness under the 520m of sediment. This BABB is divided into upper aphyric pillow (Unit 1) and lower massive flow (Unit 2) divided at the 560 mbsf, and show variable degree of alteration, clay mineral and zeolite depositions. SiO2 and MgO contents of these basalts are 47-55 and 5-8 wt%. These basalts show wide variation of enrichment of alkali elements, 2.3-7.5 and 0.4-4.2 wt% of Na2O and K2O. Na2O+K2O contents show 3.2-8.0 wt%, and 2 wt% higher trends than other BABBs in the Shikoku Basin at the same SiO2 contents. Na2O and K2O show proportional and anti-proportional trends with increasing LOI. Therefore, both alkali element enrichments in these rocks are caused by secondary mineralization, and host phase of Na2O is hydrous and that of K2O is anhydrous minerals. Secondary mineral phases was mainly identified by XRD. The identified host phases of Na are analcime and thomsonite. Analcime is observed in rocks of more than 4 wt% of Na2O. Chlorite and smectite are identified to clay minerals. This mineral assemblage indicates the high-temperature zeolite facies alteration. The host phases of K are mainly identified into K-feldspar. We assume that secondary mineralization of K-fd is associated with low-temperature albitization. Compared to the lithostratigraphy, the Na enrichment is prominent in the Unit 1 and upper 20 m of the Unit 2, and the K enrichment is prominent in lower part of the Unit 2. We consider that the Na enrichment associated with zeolite depositions occurred under high water/rock ratio with active hydrothermal circulation because of high water permeability of pillow lava, and K enrichment associated with albitization occurred

  3. Reaction-path calculations of groundwater chemistry and mineral formation at Rainier Mesa, Nevada

    International Nuclear Information System (INIS)

    Reaction-patch calculations of groundwater chemistry and mineral formation at Rainier Mesa, Nevada, have been done using a model of volcanic-glass dissolution by water that is initially saturated with CO2. In the reaction-path calculation, rate processes control the availability of species through dissolution of volcanic glass, and equilibrium processes distribute the species between the aqueous phase and mineral phases in equilibrium at each step in the reaction path. The EQ3/6 chemical-equilibrium programs were used for the calculation. Formation constants were estimated for three zeolites (clinoptilolite, mordenite, and heulandite), so they could be considered as possible mineral precipitates. The first stage of mineral evolution, from volcanic glass to a cristobalite, smectite clay, and zeolite mixture, was modeled quite well. Predicted aqueous-phase compositions and precipitates agree with observations at Rainier Mesa and other Nevada Test Site areas. Further mineral evolution, to quartz, clay, analcime, and albite mixtures, was also modeled. Decreasing aqueous silica activity from the first stage, where cristobalite precipitates, to later stages, where quartz is present, was the controlling variable in the mineral evolution. 30 references, 20 figures, 4 tables

  4. Mineralogy of drill holes J-13, UE-25A No. 1, and USW G-1 at Yucca Mountain, Nevada

    International Nuclear Information System (INIS)

    The mineralogy of drill holes J-13, UE-25A No. 1, and USW G-1 was previously determined using qualitative and semiquantitative techniques, and most of the available data were neither complete nor accurate. New quantitative x-ray diffraction data were obtained for rocks from all three of these drill holes at Yucca Mountain, Nevada. These quantitative analyses employed both external and internal standard x-ray powder diffraction methods and permitted the precise determination of all phases commonly found in the tuffs at Yucca Mountain, including glass and opal-CT. These new data supplant previous analyses and include numerous additional phases. New findings of particular importance include better constraints on the distribution of the more soluble silica polymorphs, cristobalite and opal-CT. Opal-CT was associated solely with clinoptilolite-bearing horizons, and cristobalite disappearance coincided with the appearance of analcime in USW G-1. Unlike previous analyses, we identified significant amounts of smectite in drill hole J-13. We found no evidence to support previous reports of the occurrence of erionite or phillipsite in these drill holes

  5. Shock-compression on Eu2O3 doped pollucite phosphors

    Science.gov (United States)

    Hamada, Sho; Kishimura, Hiroaki; Aruga, Atsushi; Matsumoto, Hitoshi

    2015-06-01

    Pollucite CsAlSi2O6 is a natural mineral belong to zeolite group formed with analcime, and general formula is following: (Cs,Na)16Al16Si32O96 .n(H2O). The crystal structure of pure CsAlSi2O6 is cubic(Ia-3d) and unit cell is 136645 nm Pollucite is stable stone yielding on the surface of the Earth since ancient times and is used to as a raw material of Cs element. Eu2O3-doped pollucite phosphors are efficient white phosphor for Application of deep-UV -light emitting diode (LED). Phosphors were prepared by solid-state reaction. 1 mol% Eu2O3-doped and 3 mol% Eu2O3-doped pollucites were prepared. Shock-recovery experiments were conducted involving the impact of a flyer plate accelerated by a single-stage powder-propellant gun. The recovered samples were characterized by X-ray diffraction (XRD) analysis and photoluminescence (PL) spectroscopy. The XRD and PL results of samples shocked at pressures of 22 GPa indicated that dissolution and amorphous-to-crystalline transformation occurred. In addition, emission peak wavelength of 3 mol% Eu2O3-doped sample shift 20 nm (520 -->500 nm). As a result, it is considered that Eu2+ moved in the crystalline by shock-compression.

  6. Precipitation of nitrate-cancrinite in Hanford Tank Sludge.

    Science.gov (United States)

    Buck, E C; McNamara, B K

    2004-08-15

    The chemistry of underground storage tanks containing high-level waste at the Hanford Site in Washington State is an area of continued research interest. Thermodynamic models have predicted the formation of analcime and clinoptilolite in Hanford tanks, rather than cancrinite; however, these predictions were based on carbonate-cancrinite. We report the first observation of a nitrate-cancrinite [possibly Na8(K,Cs)(AlSiO4)6(NO3)2 x nH2O] extracted from a Hanford tank 241-AP-101 sample that was evaporated to 6, 8, and 10 M NaOH concentrations. The nitrate-cancrinite phase formed spherical aggregates (4 microm in diameter) that consisted of platy hexagonal crystals (approximately 0.2 microm thick). Cesium-137 was concentrated in these aluminosilicate structures. These phases possessed a morphology identical to that of nitrate-cancrinite synthesized using simulant tests of nonradioactive tank waste, supporting the contention that it is possible to develop nonradioactive artificial sludges. This investigation points to the continued importance of understanding the solubility of NO3-cancrinite and related phases. Knowledge of the detailed structure of actual phases in the tank waste helps with thermodynamic modeling of tank conditions and waste processing. PMID:15382874

  7. Physical, chemical and mineralogical characterisation of hydraulically disposed fine coal ash from SASOL Synfuels

    Energy Technology Data Exchange (ETDEWEB)

    Jabulani S. Mahlaba; Elsabe P. Kearsley; Richard A. Kruger [University of Pretoria, Pretoria (South Africa). Civil Engineering

    2011-07-15

    Coal serves as the primary energy source in most parts of the world. It is a fact that coal combustion yields enormous quantities of fly ash some of which are either hydraulically placed or dry dumped. The current study attempts to provide a comprehensive characterisation of a disused alkaline fine coal ash dam (FCAD) towards assessing environmental impact, rehabilitation and utilisation potential. Fine coal ash refers to a combination of approximately 83% power station fly ash and 17% gasification and bottom ash fines (particles {lt}250 {mu}m) at SASOL Synfuels. The hydration products found in Weathered Fine Coal Ash (WFCA) using X-ray Diffraction (XRD) and Differential Scanning Calorimetry (DSC) are analcime, calcite, C-S-H gel, ettringite, hydrated gehlenite (Strtlingite), magnetite, periclase, pyrrhotite and sillimanite. High resolution Scanning Electron Microscope (SEM) results provide additional proof that hydration products are present in WFCA. No indication of appreciable leaching was given by X-ray Fluorescence (XRF) results except calcium and silicon. Thus evidence exists that pollutants from saline brines are immobilised in WFCA and an insight of reaction kinetics was obtained. High content of amorphous phase and lack of alteration in some geotechnical properties suggest that WFCA can be reutilised with lime addition to increase alkalinity and activate pozzolanic reactions. 48 refs., 18 figs., 4 tabs.

  8. Fly ash from a Mexican mineral coal. II. Source of W zeolite and its effectiveness in arsenic (V) adsorption

    International Nuclear Information System (INIS)

    Coal-fired plants in Coahuila (Mexico) produce highly reactive fly ash (MFA), which is used in a one-step process as a raw material in producing zeolite. We explored two routes in the synthesis of zeolite: (a) direct MFA zeolitization, which resulted in the formation of W zeolite with KOH and analcime with NaOH and (b) a MFA fusion route, which resulted in the formation of zeolite W or chabazite with KOH and zeolite X or P with NaOH. No residual crystalline phases were present. When LiOH was employed, ABW zeolite with quartz and mullite were obtained. For both zeolitization routes, the nature of the alkali (KOH, NaOH, LiOH), the alkali/MFA ratio (0.23-1.46), and the crystallization temperature and time (90-175 oC; 8-24 h) were evaluated. Additionally, the effect of temperature and time on MFA fusion was studied. W zeolite was obtained by both zeolitization methods. The direct route is preferred because it is a straightforward method using soft reaction conditions that results in a high yield of low cost zeolites with large crystal agglomerates. It was demonstrated that aluminum modified W zeolite has the ability to remove 99% of the arsenic (V) from an aqueous solution of Na2HAsO4.7H2O originally containing 740 ppb.

  9. Catalytic decarboxylations of fatty acids in immature oil source rocks

    Institute of Scientific and Technical Information of China (English)

    李哲; 张再龙; 孙燕华; 劳永新; 蔺五正; 吴卫芳

    2003-01-01

    Catalytic decarboxylations of fatty acids in immature oil source rock samples were examined in this study. The rock samples were obtained from seven oil fields in China. In order to clarify the effect of each mineral matter in the rock samples, both the Fe M?ssbauer effect and the X-ray diffraction (XRD) were used to determine the relative content of each mineral in the rock samples, and the catalytic activities of several minerals like clays, carbonates and pyrite were determined. The Fe M?ssbauer effect and the XRD studies show that clays are the main mineral components in the rock samples except for the samples from Biyang and Jianghan in which the main mineral component is ankerite. The other mineral components include calcite, plagioclase, quartz, feldspar, siderite, aragonite, pyrite, analcime, pyroxene and anhydrite. The studies of the catalytic decarboxylations of fatty acids suggest that carbonates and pyrite can make much greater contributions to the catalytic activities of the rock samples than clays. It is found that the overall catalytic activities of the rock samples are well related to the relative contents and the catalytic activities of clays, carbonates and pyrite in the rock samples.

  10. Fly ash from a Mexican mineral coal. II. Source of W zeolite and its effectiveness in arsenic (V) adsorption

    Energy Technology Data Exchange (ETDEWEB)

    Medina, Adriana [CINVESTAV IPN-Unidad Saltillo, Carretera Saltillo-Monterrey Km 13.5, C.P. 25900, Ramos Arizpe, Coahuila (Mexico); Gamero, Procoro, E-mail: pgamerom@hotmail.com [CINVESTAV IPN-Unidad Saltillo, Carretera Saltillo-Monterrey Km 13.5, C.P. 25900, Ramos Arizpe, Coahuila (Mexico); Almanza, Jose Manuel [CINVESTAV IPN-Unidad Saltillo, Carretera Saltillo-Monterrey Km 13.5, C.P. 25900, Ramos Arizpe, Coahuila (Mexico); Vargas, Alfredo; Montoya, Ascencion [Instituto Mexicano del Petroleo, Eje Central Lazaro Cardenas 152, G.A. Madero, C.P. 07730, Distrito Federal (Mexico); Vargas, Gregorio [CINVESTAV IPN-Unidad Saltillo, Carretera Saltillo-Monterrey Km 13.5, C.P. 25900, Ramos Arizpe, Coahuila (Mexico); Izquierdo, Maria [Instituto de Ciencias de la Tierra ' Jaume Almera' , CSIC, C/Luis Sole Sabaris, s/n 08028 Barcelona (Spain)

    2010-09-15

    Coal-fired plants in Coahuila (Mexico) produce highly reactive fly ash (MFA), which is used in a one-step process as a raw material in producing zeolite. We explored two routes in the synthesis of zeolite: (a) direct MFA zeolitization, which resulted in the formation of W zeolite with KOH and analcime with NaOH and (b) a MFA fusion route, which resulted in the formation of zeolite W or chabazite with KOH and zeolite X or P with NaOH. No residual crystalline phases were present. When LiOH was employed, ABW zeolite with quartz and mullite were obtained. For both zeolitization routes, the nature of the alkali (KOH, NaOH, LiOH), the alkali/MFA ratio (0.23-1.46), and the crystallization temperature and time (90-175 {sup o}C; 8-24 h) were evaluated. Additionally, the effect of temperature and time on MFA fusion was studied. W zeolite was obtained by both zeolitization methods. The direct route is preferred because it is a straightforward method using soft reaction conditions that results in a high yield of low cost zeolites with large crystal agglomerates. It was demonstrated that aluminum modified W zeolite has the ability to remove 99% of the arsenic (V) from an aqueous solution of Na{sub 2}HAsO{sub 4}.7H{sub 2}O originally containing 740 ppb.

  11. Smectite-zeolite envelope surrounding the Tsukiyoshi uranium deposit, central Japan. A natural analogue study

    International Nuclear Information System (INIS)

    The Tsukiyoshi uranium deposit in Gifu Prefecture is the largest one in Japan. It is embedded in lower part of the Mizunami Group of Miocene age. Relating to the existence of this uranium deposit, the constituent minerals in sediments were studied by XRD and SEM, using many drilling cores. The most abundant authigenic mineral is smectite. The amount of smectite increases generally from upper to lower horizons, and a highly smectitized zone is situated around the uranium deposit. Smectitization predominated in mafic glassy grains of sediments, which was probably formed in early burial diagenesis. Zeolites including clinoptilolite-heulandite, mordenite, analcime, chabazite and philipsite are secondly abundant authigenic minerals. They seem to have been formed at early to late diagenetic stages. Opaline silica is rather rare. Carbonate minerals, including calcite, dolomite, siderite and rhodocrosite are common. They may be formed by diagenesis as well. Gypsum and pyrite occur in upper horizons and lower horizons, respectively. In particular, a highly smectitized zone including pyrite probably played an important role for retarding the migration of uranium and as a result keeping the uranium deposit for past one million years. This smectite-zeolite envelope surrounding the Tsukiyoshi uranium deposit is regarded as a natural analogue of the buffer materials surrounding the high-level radioactive waste repository. (author)

  12. Surface alteration of sintered product of strontium aluminum silicate under hydrothermal conditions

    International Nuclear Information System (INIS)

    The surface alteration of strontium aluminum silicate has been studied under hydrothermal conditions in connection with the leachability of Sr from solidified radioactive wastes. Samples exposed to a 3 M NaCl solution at 300 C produced a precipitated layer of analcime (NaAlSi2O6) with high crystallinity. The normalized leach rates for Sr in 3 M NaCl and 3 M KCl solutions were found to be less than 10-3 g/cm2·d, yielding high resistance to leaching in these solutions. On exposure to the CaCl2 solution at 300 C, anorthite (CaAl2Si2O8) was formed on the surface, indicating the replacement of Sr with Ca through isomorphous substitution. In the case of MgCl2 solution, a thick precipitated layer of clinochlore (Mg5Al(Si3Al)O10(OH)8) built up on the outermost surface. This layer serves to depress the migration of Sr, resulting in the deposition of SrCl2 salts in the altered layer

  13. Origin of lacustrine dolostones of the Middle Permian Lucaogou Formation in Santanghu Basin of Xinjiang%新疆三塘湖盆地中二叠统芦草沟组湖相白云岩成因

    Institute of Scientific and Technical Information of China (English)

    李红; 柳益群; 梁浩; 周小虎; 焦鑫; 刘洪福; 杨锐; 雷川

    2012-01-01

    .48. Morphologically, the dolomite was divided into micro-rhombohedra, xenomorphic crystal, microsphere, and microtubule types under the SEM. Part of the micro-rhombohedra dolomite was ferric dolomite. The other kind of dolostone was named analcime-sanidine dolostone which was composed of fine grained analcime with the granularity of 0. 08 ~ 0. 35 mm, micrite potash feldspar ( almost sanidine ) , micrite dolomite, ankerite, and few coarse crystalline dolomite. This kind of dolomite also showed weak ordering with degree of 0.58. Compared with the dolomites in silt-micrite dolostone, the dolomites in analcime-sanidine dolostone which were almost subhedral rhombohedras under the SEM were characterized as high iron and manganese. The similarities between these two dolostones were that they were poor ordering dolomites, abundant in strontium, and lacking of the evidence in replacement during the buried period. Although these two dolostones were deposited in the similar shallow and semi-deep lake anoxic reduction environment, their differences in composition, trace elements and stable isotopes indicated that they had great diversity in their genesis. The silt-micrite dolostone revealed the features of primary precipitation. The microbe was likely to play a formative role in the precipitation of the microspheroidal and microtubular dolomites. Moreover, the micro-rhombohedrala and xenomorphic dolomites were directly precipitated from lake water. Contrastly, the dolomites in analcime-sanidine dolostone were precipitated by the hydrothermal exhalative processes of the sublacustrine hotsprings.

  14. Mineralogy and origin of rhizoliths on the margins of saline, alkaline Lake Bogoria, Kenya Rift Valley

    Science.gov (United States)

    Owen, Richard Alastair; Owen, Richard Bernhart; Renaut, Robin W.; Scott, Jennifer J.; Jones, Brian; Ashley, Gail M.

    2008-01-01

    A wide range of rhizoliths occurs around the margins of Lake Bogoria, Kenya. These include root casts, moulds, tubules, rhizocretions, and permineralised root systems. These rhizoliths are variably composed of opaline silica, calcite, zeolites (mainly analcime), fluorite, and possibly fluorapatite, either alone or in combinations. Some rhizoliths are infilled moulds with detrital silicate grains. Most rhizoliths are in situ, showing both vertical and horizontal orientations. Reworked rhizoliths have been concentrated locally to form dense rhizolites. Hot-spring fluids, concentrated by evapotranspiration and capillary evaporation, have provided most of the silica for the permineralisation of the plant tissues. Precipitation involved the growth of silica nanospheres and microspheres that coalesced into homogeneous masses. Calcite rhizoliths formed following evaporative concentration, evapotranspiration, and (or) CO 2 degassing of Ca-bearing runoff water that infiltrated the sediment, or by mixing of runoff with saline, alkaline groundwater. Fluorite precipitated in areas where mixing of hot-spring and meteoric waters occurred, or possibly where hot-spring fluids came into contact with pre-existing calcite. Zeolitic rhizoliths formed during a prolonged period of aridity, when capillary rise and evaporative pumping brought saline, alkaline waters into contact with detrital silicate minerals around roots.

  15. Chemistry of glass corrosion in high saline brines

    International Nuclear Information System (INIS)

    Corrosion data obtained in laboratory tests can be used for the performance assessment of nuclear waste glasses in a repository if the data are quantitatively described in the frame of a geochemical model. Experimental data were obtained for conventional pH values corrected for liquid junction, amorphous silica solubility and glass corrosion in concentrated salt brines. The data were interpreted with a geochemical model. The brine chemistry was described with the Pitzer formalism using a data base which allows calculation of brine compositions in equilibrium with salt minerals at temperatures up to 200C. In MgCl2 dominated brines Mg silicates form and due to the consumption of Mg the pH decreases with proceeding reaction. A constant pH (about 4) and composition of alteration products is achieved, when the alkali release from the glass balances the Mg consumption. The low pH results in high release of rare earth elements REE (rare earth elements) and U from the glass. In the NaCl dominated brine MgCl2 becomes exhausted by Mg silicate formation. As long as there is still Mg left in solution the pH decreases. After exhaustion of Mg the pH rises with the alkali release from the glass and analcime is formed

  16. Characterisation and potential economic interest of authigenic zeolites in continental sediments from NW Mexico

    Science.gov (United States)

    Cochemé, J.-J.; Lassauvagerie, A.-C.; Gonzalez-Sandoval, J.; Perez-Segura, E.; Münch, P.

    1996-09-01

    In NW Mexico, zeolite deposits of potential economic interest occur in continental sediments related to mid-Tertiary basin and range tectonism. In central Sonora, where the stratigraphic column is thicker (e.g. in the Moctezuma Basin), two superposed sequences of sediments are distinguished on the basis of their lithology and stratigraphy. They are known as the Baucarit Formation. The lower sequence, Miocene in age and 300 to 400 m thick, is indurated and consists mainly of sandstones and conglomerates. The upper one, of variable thickness, consists of clays. Zeolites occur in both sequences as alteration products of volcanic glass in beds of white intercalated rhyolitic tuff. Previously known outcrops of zeolitites from Rio Batepito (erionite), Tetuachi and San Pedro Ures (heulandite group), Divisaderos (chabazite) and several other newly discovered occurrences are described in this work in terms of mineral association, physical properties (porosity, thermal behaviour) and chemical characteristics (major and trace elements for individual crystals and bulk rock). Heulandite-group minerals are also present as cement (30% by volume) of the sandstones from the lower sequence. Amygdales and veins from basaltic flows intercalated within the lowest sediments contain a large variety of zeolite species: chabazite, stilbite, phillipsite, mesolite, erionite, thomsonite, heulandite and analcime. Zeolites in the pyroclastic beds intercalated in the upper sequence represent the highest economic potential because they are essentially monomineralic and constitute up to 80% in volume of the whole rock. Because of the inhomogeneous distribution of amygdales, zeolites in the basaltic flows have a low economic interest.

  17. Propagation of a hyperalkaline plume into the geological barrier surrounding a radioactive waste repository

    International Nuclear Information System (INIS)

    A coupled geochemical transport model (MPATH) which includes chemical reaction kinetics is used to evaluate the alteration of Swiss argillaceous sediments in a high-pH environment and to predict the spatial propagation of the hyperalkaline plume with time. The calculations predict dissolution of quartz, clay minerals and chlorite, and precipitation of zeolite minerals such as analcime and natrolite as well as he feldspars K-feldspar and albite. In addition, Portland cement-hydrates such as calcium silicate and aluminate hydrates, ettringite and friedel-salt are also predicted to form, depending on the composition of the inlet fluid and the host rock. The dissolution of clay minerals reduces the pH of the hyperalkaline plume to levels between approximately 8 and 10, depending on the composition of the inlet fluid and the host rock. For pure advective transport through porous medium, neglecting changes in porosity and permeability, the migration velocity of the high-pH front is calculated to be approximately one to two orders of magnitude less than that of the infiltrating groundwater. However, due to precipitation of secondary phases, in the present model concept a rapid decrease in porosity of the marl occurs several meters from the repository. At the interface between the marl host rock and cement the porosity increases as a consequence of the low silica concentration of the cement pore fluid. (author) 10 figs., 7 tabs., refs

  18. Synthesis of zeolites from boiler fly ash: physical, chemical and mineralogical characterization

    International Nuclear Information System (INIS)

    Along the years, worldwide industrial development has causing a growing generation of residues, bringing potentials environmental problems. A study of the characteristics of these wastes, as well as the development of techniques for their use in new processes becomes indispensable for the environment preservation. The main purpose of this work is to evaluate the possible use of two important industrial residues from the Amazon region for zeolite synthesis: (a) the fly ash (particle size 2O/Al2O3 molar ratio of 5 and Si/Al molar ratio ranging from 2.12 to 15, and reaction time of 24 h. The results of the fly characterization demonstrate its enormous potential as raw material for the zeolite synthesis. SiO2 and Al2O3 represent more than 50% of its composition, mineralogical phases defined, low humidity content, low particle size (d90 < 10 μm), among others. Mineralogical analyses of the synthesized products showed the formation of some zeolite types, as follow: analcime, phillipsite, sodalite, zeolite P and tobermorite. The results show that the mixture fly ash-micro silica in these reaction conditions point to a promising material for zeolite synthesis (author)

  19. Synthesis of high capacity cation exchangers from a low-grade Chinese natural zeolite

    International Nuclear Information System (INIS)

    The Chinese natural zeolite, in which clinoptilolite coexists with quartz was treated hydrothermally with NaOH solutions, either with or without fusion with NaOH powder as pretreatment. Zeolite Na-P, Na-Y and analcime were identified as the reacted products, depending on the reaction conditions such as NaOH concentration, reaction time and hydrothermal temperature. The products were identified by X-ray diffraction, and characterized by Fourier transform IR and ICP. With hydrothermal treatment after fusion of natural zeolite with NaOH, high purity of zeolite Na-Y and Na-P can be selectively formed, their cation exchange capacity (CEC) are 275 and 355 meq/100 g respectively, which are greatly higher than that of the natural zeolite (97 meq/100 g). Furthermore, the ammonium removal by the synthetic zeolite Na-P in aqueous solution was also studied. The equilibrium isotherms have been got and the influence of other cations present in water upon the ammonia uptake suggested an order of preference Ca2+ > K+ > Mg2+.

  20. Zeolite stability constraints on radioactive waste isolation in zeolite-bearing volcanic rocks

    International Nuclear Information System (INIS)

    Silicic tuffs of the southern Great Basin and basalts of the Columbia River Plateau are under investigation as potential host rocks for high- and intermediate-level radioactive wastes. Non-welded and partially welded tuffs may contain major amounts (> 50%) of the zeolite minerals: clinoptilolite, mordenite, and analcime. Densely welded tuffs and some basalt flows may contain clinoptilolite as fracture filling which limits permeability of these rocks. The cation exchange properties of these zeolite minerals allow them to pose a natural barrier to the migration of cationic species of various radionuclides in aqueous solutions. However, these minerals are unstable at elevated temperatures and at low water vapor pressures, and they may break down either by reversible dehydration or by irreversible mineralogical reactions. All of the breakdown reactions occurring with increased temperature involve a net volume reduction and evolution of fluids. Thus, they may provide both a pathway (shrinkage fractures) and a driving force (fluid pressure) for release of radionuclides to the biosphere. These reactions may be avoided by keeping zeolite-bearing horizons saturated with water and below about 850C. This may restrict allowable gross thermal loadings in radioactive waste repositories in zeolite-bearing volcanic rocks. 3 figures

  1. Mineralogía de los materiales de la Formación de La Viñuela (Cordilleras Béticas

    Directory of Open Access Journals (Sweden)

    Galán, E.

    1984-12-01

    Full Text Available Mineralogy of several samples from the Viñuela Formation,Lower Burdigalian (Vélez Málaga, Cordilleras Béticas, has been studied. Materials are composed of abundant microfauna. and pebbles of micaschits, quartzites and other materials, from the Alpujárrides and Maláguides Nappes, cemented by a micritic matrix . Most samples contain zeolites (clinoptilolite, mordenite and analcime, and illite chlorite, interstratified clay minerals, montmorillonite and opal C-T. A diagenetic genesis for zeolites is suggested.

    Se ha estudiado la composición mineralógica de unas muestras de la serie tipo de la Formación de La Viñuela (norte de Vélez Málaga, Cordilleras Béticas, datadas como Burdigaliense inferior. Se trata de sedimentos marinos carbonatados micríticos, con abundante microfauna. que cementan cantos de micaesquistos, cuarcitas y otros materiales procedentes de los mantos alpujárrides y maláguides. En gran parto de estas muestras se han encontrado zeolitas (clinoptilolita, mordenita y analcima, así como illita, clorita, interestratificados, montmorillonita y ópalo C-T. Se atribuye a las zeolitas un origen diagenético.

  2. High to ultrahigh potassic alkaline volcanic belt along the Ankara-Erzincan suture (northern Turkey): new geochemical and Ar-Ar data constraining petrogenesis with implications for the late Cretaceous subduction of the Neotethys Ocean

    Science.gov (United States)

    Genc, S. Can; Gulmez, Fatma; Tuysuz, Okan; Karacik, Zekiye; Roden, Michael F.; Zeki Billor, M.; Hames, Willis E.

    2013-04-01

    Remnants of some high- to ultrahigh-K alkaline volcanic rocks crop out as isolated small and discontinuous bodies along the Ankara-Erzincan suture belt in northern Turkey. These rocks are represented by leucite-bearing lavas (LB), basaltic andesites, trachytes, monzonite/syenites) and lamprophyres. Leucite-bearing rocks are small stocks, dikes and lava flows. Pebbles and blocks of the LB are found in the coeval volcanic debris avalanche deposits and volcanoclastic breccias. Leucite-bearing rocks are mainly phonotephrite, tephriphonolite, trachyandesite and basaltic trachyandesites (shoshonite) and have mineral assemblages of lct + cpx + ol + pl + Kfs + mag+ ap. Leucites were almost totally analcimized. Trachytes and monzonite/syenites, which are seen as small stocks and dikes, are characterized by amp + bt + pl + Kfs + spn + ap + opq paragenesis. Lamprophyres are mica-rich melanocratic dikes, and include cpx + mica (phlogopitic) + Kfs + ap + opq. Rarely leucite, olivine and plagioclase are also present. Ar-Ar data reveal that this volcanic activity occurred between 73.6±0.18 and 76.78±0.19 Ma, corresponding to latest Cretaceous. All the samples from the high- and ultrahigh-K volcanic belt are alkaline in nature. Leucite-bearing lavas are characterized by their MgO (2.70-5.81, av. 4.58 wt.%), K2O (0.79-4.81, av. 2.35 wt.%), Na2O (4.86-7.48, av. 3.58 wt.%) and K2O/Na2O (0.13-0.92, av. 0.42 wt.%). The low K2O and K2O/Na2O contents of these rocks are due to extensive analcimization of the leucites. Major oxide contents in lamprophyric rocks are 3.25-7.48 (MgO), 1.35-7.76 (K2O), 1.77-4.00 (Na2O) and 0.31-2.69 (K2O/Na2O). The silica content of these rocks are variable and range from 47.18-50.26 (wt.%) (LB) to 39.14-53.28 (lamprophyres). Based on their major element contents, these rocks are classified as plagioleucitites or ultrapotassic rocks of the active orogenic zones (Foley, 1992). Leucite-bearing rocks, lamprophyres and the trachytes (with their hypabyssal

  3. Geologic History of a Felsic and Hydrated Mineral Suite in Syrtis Major

    Science.gov (United States)

    Smith, M. R.; Bandfield, J. L.; Gillespie, A.

    2010-12-01

    Here we assess the ancient environments represented by the compositions of exposures within two craters near Antoniadi Crater in N. Syrtis Major, Mars (63°E, 20°N). We used both thermal (TIR) and visible/near-infrared (VNIR) spectroscopy to place constraints on the mineralogy, formation environment, and astrobiological potential. This region was chosen because of its varied and well-exposed mineralogy. It was first studied in the TIR because of its unique exposures of quartz- and feldspar-rich surfaces1, representing both the only current identification of crystalline quartz and the most felsic composition yet found on Mars. VNIR data acquired within the same region reveal a suite of hydrated minerals, including phyllosilicates, hydrated silica (opal), and the zeolite analcime2. In this study, we utilize the combined stability fields of the full suite of quartzofeldspathic and hydrated minerals - a unique mineral assemblage on Mars - to infer formation conditions: neutral-to-alkaline pH, low-to-moderate temperatures, and sustained water. These conditions have been cited as ideal for providing a habitable environment for nascent life3. We answer three main questions about the alteration history of these deposits: When did alteration occur? Alteration is thought to either pre-date the impact or occur in a post-impact hydrothermal cell. Our study suggests the former, since alteration is restricted to impact breccia blocks, indicating that altered rocks had formed and were later exhumed by impact. How are the quartzofeldspathic and hydrated minerals related? Quartzofeldspathic material exposed within these craters is always co-located with opal. Opal is metastable and will alter to chalcedony (microcrystalline quartz) in 400 Ma under martian conditions4 with sustained exposure to water5. In the TIR, species of opal are separable6, but spectra of chalcedony and quartz share a distinctive doublet between 8-9.5 μm7, and are mostly indistinguishable. However, in the

  4. Metamorfismo de muy bajo grado asociado a un sistema geotermal en rocas volcánicas básicas del Jurásico Medio, Formación Lonco Trapial, Paso Berwin, Chubut extra-andino Very low grade metamorphism associated with a geothermal system in basic volcanic rocks of the Middle Jurassic, Lonco Trapial Formation, Paso Berwin, Extra-Andean Chubut

    Directory of Open Access Journals (Sweden)

    P. Montecinos

    2004-12-01

    Full Text Available Las rocas volcánicas básicas de la Formación Lonco Trapial, poseen una mineralogía primaria compuesta principalmente por olivino, plagioclasa cálcica y piroxeno, presentando además gran cantidad de amígdalas. La mineralogía metamórfica de muy bajo grado en estas rocas está caracterizada por ceolitas, minerales arcillosos y micáceos. La asociación mineral más característica está compuesta por celadonita, montmorillonita, heulandita, analcima, gonnardita y, además, por levyna y minerales de la serie analcima-wairakita en forma subordinada. Esta asociación pertenece a la facies ceolita y tuvo un origen asociado a un sistema geotermal. La analogía establecida con las zonas de ceolitas conocidas para sistemas geotermales equivalentes y el uso de la grilla petrogénetica para paragénesis ceolíticas, en el sistema An-Ab-SiO2-H2O, permiten establecer un rango de temperatura entre 80°-180°C. En este contexto habría ocurrido un único evento metamórfico hidrotermal en presencia de una fase fluida, muy pobre en CO2, cuya composición química habría cambiado desde un carácter neutro con baja a(SiO2 y a(K2O moderada (permitiendo la precipitación de esmectitas y celadonita a un carácter neutro-alcalino con a(SiO2 que posibilita la estabilidad de la heulandita.The basic volcanic rocks of the Lonco Trapial Formation, have a primary mineralogy mainly composed of olivine, calcic plagioclase and pyroxene, and present a large quantity of amygdales. Their metamorphic mineralogy is characterized by zeolites, clay and micaceous minerals. The main mineral association includes celadonite, montmorillonite, heulandite, analcime, gonnardite and subordinate levyne and minerals of the wairakite-analcime series. This association belongs to the zeolite facies and its origin was associated with a geothermal system. The analogy with known zeolite zones in equivalent geothermal systems and the use of the petrogenetic grid for zeolite parageneses, in

  5. Environmental effect and genetic influence: a regional cancer predisposition survey in the Zonguldak region of Northwest Turkey

    Science.gov (United States)

    Kadir, Selahattin; Önen-Hall, A. Piril; Aydin, S. Nihal; Yakicier, Cengiz; Akarsu, Nurten; Tuncer, Murat

    2008-03-01

    The Cretaceous-Eocene volcano-sedimentary units of the Zonguldak region of the western Black Sea consist of subalkaline andesite and tuff, and sandstone dominated by smectite, kaolinite, accessory chlorite, illite, mordenite, and analcime associated with feldspar, quartz, opal-CT, amphibole, and calcite. Kaolinization, chloritization, sericitization, albitization, Fe-Ti-oxidation, and the presence of zeolite, epidote, and illite in andesitic rocks and tuffaceous materials developed as a result of the degradation of a glass shards matrix, enclosed feldspar, and clinopyroxene-type phenocrysts, due to alteration processes. The association of feldspar and glass with smectite and kaolinite, and the suborientation of feldspar-edged, subparallel kaolinite plates to fracture axes may exhibit an authigenic smectite or kaolinite. Increased alteration degree upward in which Al, Fe, and Ti are gained, and Si, Na, K, and Ca are depleted, is due to the alteration following possible diagenesis and hydrothermal activities. Micromorphologically, fibrous mordenite in the altered units and the presence of needle-type chrysotile in the residential buildings in which cancer cases lived were detected. In addition, the segregation pattern of cancer susceptibility in the region strongly suggested an environmental effect and a genetic influence on the increased cancer incidence in the region. The most likely diagnosis was Li-Fraumeni syndrome, which is one of the hereditary cancer predisposition syndromes; however, no mutations were observed in the p53 gene, which is the major cause of Li-Fraumeni syndrome. The micromorphology observed in the altered units in which cancer cases were detected may have a role in the expression of an unidentified gene, but does not explain alone the occurrence of cancer as a primary cause in the region.

  6. Corrosion behavior of environmental assessment glass in product consistency tests of extended duration

    International Nuclear Information System (INIS)

    We have conducted static dissolution tests to study the corrosion behavior of the Environmental Assessment (EA) glass, which is the benchmark glass for high-level waste glasses being produced at US Department of Energy facilities. These tests were conducted to evaluate the behavior of the EA glass under the same long-term and accelerated test conditions that are being used to evaluate the corrosion of waste glasses. Tests were conducted at 90 C in a tuff groundwater solution at glass surface area/solution volume (WV) ratios of about 2000 and 20,000 m-1. The glass dissolved at three distinct dissolution rates in tests conducted at 2000 m-1. Based on the release of boron, dissolution within the first seven days occurred at a rate of about 0.65 g/(m2 · d). The rate between seven and 70 days decreased to 0.009 g/(m2 · d). An increase in the dissolution rate occurred at longer times after the precipitation of zeolite phases analcime, gmelinite, and an aluminum silicate base. The dissolution rate after phase formation was about 0.18 g/(m2 · d). The formation of the same zeolite alteration phases occurred after about 20 days in tests at 20,000 m-. The average dissolution rate over the first 20 days was 0.5 g/(m2 · d) and the rate after phase formation was about 0.20 g/(m2 · d). An intermediate stage with a lower rate was not observed in tests at 20,000 m-1. The corrosion behavior of EA glass is similar to that observed for other high-level waste glasses reacted under the same test conditions. The dissolution rate of EA glass is higher than that of other high-level waste glasses both in 7-day tests and after alteration phases form

  7. ANL technical support program for DOE Office of Environmental Management. Annual report, October 1994--September 1995

    International Nuclear Information System (INIS)

    A program was established for the DOE Office of Environmental Management (EM) to evaluate factors that are anticipated to affect waste glass reaction during repository disposal, especially in an unsaturated environment typical of what may be expected for the proposed Yucca Mountain repository site. This report covers progress in FY 1995 on the following tasks: (1) Tests are ongoing to evaluate and compare the reactivity of fully radioactive glasses with that of glasses having the same compositions except for the absence of radionuclides under conditions representative of a high-level waste repository environment. Data from these tests will be used to evaluate the effect of radionuclides on the glass corrosion behavior and to determine the disposition of the radionuclides as the glass corrodes. Static dissolution tests and unsaturated tests are being conducted with several Defense Waste Processing Facility (DWPF) and West Valley Demonstration Project (WVDP) glasses. (2) A series of static dissolution tests is being performed to compare the corrosion behavior of nuclear waste glasses made with SRL 131 and SRL 202 frits at different S/V ratios. The S/V ratio affects the extent to which dissolved glass species are diluted; the solution chemistry then affects continued glass dissolution. The solutions generated in tests at high S/V ratios are conducive to the formation of alteration phases that may be deleterious to the glass. After long time periods, the glass dissolution rates of both glasses increase coincidentally with the formation of analcime and other alteration phases. However, the release of radionuclides from the glasses into solution is controlled by their individual solubilities

  8. ANL technical support program for DOE Office of Environmental Management. Annual report, October 1994--September 1995

    Energy Technology Data Exchange (ETDEWEB)

    Bates, J.K.; Buck, E.C.; Dietz, N.L.; DiSanto, T.; Ebert, W.L. [and others

    1996-07-01

    A program was established for the DOE Office of Environmental Management (EM) to evaluate factors that are anticipated to affect waste glass reaction during repository disposal, especially in an unsaturated environment typical of what may be expected for the proposed Yucca Mountain repository site. This report covers progress in FY 1995 on the following tasks: (1) Tests are ongoing to evaluate and compare the reactivity of fully radioactive glasses with that of glasses having the same compositions except for the absence of radionuclides under conditions representative of a high-level waste repository environment. Data from these tests will be used to evaluate the effect of radionuclides on the glass corrosion behavior and to determine the disposition of the radionuclides as the glass corrodes. Static dissolution tests and unsaturated tests are being conducted with several Defense Waste Processing Facility (DWPF) and West Valley Demonstration Project (WVDP) glasses. (2) A series of static dissolution tests is being performed to compare the corrosion behavior of nuclear waste glasses made with SRL 131 and SRL 202 frits at different S/V ratios. The S/V ratio affects the extent to which dissolved glass species are diluted; the solution chemistry then affects continued glass dissolution. The solutions generated in tests at high S/V ratios are conducive to the formation of alteration phases that may be deleterious to the glass. After long time periods, the glass dissolution rates of both glasses increase coincidentally with the formation of analcime and other alteration phases. However, the release of radionuclides from the glasses into solution is controlled by their individual solubilities.

  9. The chemical evolution of Kurnub Group palcowater in the Sinai-Negev province - A mass balance approach

    Science.gov (United States)

    Rosenthal, E.; Jones, B.F.; Weinberger, G.

    1998-01-01

    The chemical evolution of the Kurnub Group paleowater was studied starting from rainwater in recharge areas of the Sinai and along groundwater flowpaths leading to the natural outlets of this regional aquifer. This was achieved by investigating the chemical composition of groundwater, ionic ratios, degrees of saturation with common mineral species, normative analysis of dissolved salts and by modeling of rock/water interaction and mixing processes occurring along groundwater flow paths. The initial groundwater composition used is from the Nakhel well in Sinai. It evolves from desert rainwater percolating through typical Kurnub Group lithology in Sinai. This rainwater dissolves mainly gypsum, halite and dolomite together with smaller amounts of marine aerosol and K-feldspar. At the same time it precipitates calcite, SiO2, smectite and degasses CO2. Between the area of Nakhel and the northern Negev the chemistry of Kurnub Group waters is influenced by dissolution of halite and lesser amounts of gypsum of surficial origin in recharge areas, small amounts of feldspars and of dolomite cement in sandstones eroded from the Arabo-Nubian igneous massif of Sinai and organic degradation-derived CO2. Concomitantly, there is precipitation of calcite, smectite, SiO2 and probably analcime characteristic of sediments in continental closed basins. North of the Negev, the Kurnub Group fluids are diluted and altered by mixing with Judea Group aquifer groundwaters. On the E there is mixing with residual brines from the water body ancestral to the Dead Sea, prior to discharge into the Arava valley. Rock/water interaction indicated by NETPATH and PHREEQC modeling is in agreement with lithology and facies changes previously observed in the Kurnub Group sequence.

  10. Indikasi mineralisasi epitermal emas bersulfi da rendah, di Wilayah Kecamatan Bonjol, Kabupaten Pasaman, Sumatera Barat

    Directory of Open Access Journals (Sweden)

    Hamdan Z. Abidin

    2014-06-01

    Full Text Available http://dx.doi.org/10.17014/ijog.vol2no1.20075Bonjol gold prospect, known as Old Dutch Gold mine, consists of several ore bodies (Malintang, Balimbing, Lubang Sempit, Lubang Belanda and Lubang Perak. The deposit hosts within the altered volcanic rocks known as Gunung Amas Formation of Early Miocene age (9.3 ± 0.4 - 11.9 ±1.0 Ma. This formation consists of various rock types such as rhyolitic tuff, volcanic breccia, dacitic tuffs and rhyolites. These rocks are moderate to strongly alter. Mineralogy of the deposit consists of gold and silver with minor pyrite, sphalerite and galena. Besides this, hematite, jarosite and manganese are also present as supergene minerals. Ore minerals are found within quartz veins ranging from few centimetres to tens of metres thick. The veins are characterized by crustiform, comb, vuggy, botroyidal, layering and bladed. Quartz is a dominant mineral as hydrothermal alteration in addition to illite, dickite, monmorillonite, kaolinite, chlorite, smectite, natrolite, nontronite, calcite, halloysite, palygorskite, muscovite, sepiolite, analcime, heulandite, clino-chlor, zircon, zoisite, laumontite, alunite, biotite and erionite. The presence of these secondary minerals could be classifi ed into prophylitic, argillic and advanced argillic types. Analytical result of gold–bearing quartz vein indicates higher content of gold (0.3% and silver (400 ppm. In contrast, the content of sulphide minerals (Cu, Pb, and Zn is very low (< 100 ppm. Combined geology, mineralogy, textures and alteration minerals, it is concluded that gold deposit in the area shows an indication of a low sulphidation epithermal type within Gunung Amas Formation.  

  11. SODIUM POLYPHOSPHATE-MODIFIED CLASS C/CLASS F FLY ASH BLEND CEMENTS FOR GEOTHERMAL WELLS.

    Energy Technology Data Exchange (ETDEWEB)

    SUGAMA, T.; BROTHERS, L.E.; KASPEREIT, D.

    2006-02-01

    The authors investigated the usefulness of the coal combustion by-products, Class C fly ash (C) and Class F fly ash (F), in developing cost-effective acid-resistant phosphate-based cements for geothermal wells. In the temperature range of 20-100 C, sodium polyphosphate (NaP) as the acidic cement-forming solution preferentially reacted with calcium sulfate and lime in the C as the base solid reactant through the exothermic acid-base reaction route, rather than with the tricalcium aluminate in C. This reaction led to the formation of hydroxyapatite (HOAp). In contrast, there was no acid-base reaction between the F as the acidic solid reactant and NaP. After autoclaving the cements at 250 C, a well-crystallized HOAp phase was formed in the NaP-modified C cement that was responsible for densifying the cement's structure, thereby conferring low water permeability and good compressive strength on the cement. however, the HOAp was susceptible to hot CO{sub 2}-laden H{sub 2}SO{sub 4} solution (pH 1.1), allowing some acid erosion of the cement. On the other hand, the mullite in F hydrothermally reacted with the Na from NaP to form the analcime phase. Although this phase played a pivotal role in abating acid erosion, its generation created an undesirable porous structure in the cement. They demonstrated that blending fly ash with a C/F ratio of 70/30 resulted in the most suitable properties for acid-resistant phosphate-based cement systems.

  12. Hydrothermal interactions of cement or mortar with zeolites or montmorillonites

    International Nuclear Information System (INIS)

    Concretes, grouts, clays and/or zeolites are candidate borehole, shaft or tunnel plugging materials for any nuclear waste repository. Interactions between these plugging materials may take place under mild hydrothermal conditions during the life of a repository. Class H cement or motar (PSU/WES mixture) was reacted with one of two montmorillonites, clinoptilolite or mordenite at 1000 and 2000C for different periods under a confining pressure of 30 MPa. The solid reaction products were characterized by x-ray powder diffraction and scanning electron microscopy after the hydrothermal treatments. When zeolites were in contact (not intimate mixture) with class H cement, they did not seem to alter but clinoptilolite altered to analcime, and mordenite became poorly crystalline in the presence of mortar (containing NaCl) at both 1000 and 2000C. When cement or mortar was intimately mixed with zeolites or montmorillonites and reacted hydrothermally, the reaction resulted in the formation of Al substituted tobermorite (11A type) in all cases (this type of reaction is expected at the interface) at both 1000 and 2000C. The mechanism of tobermorite formation includes the decomposition of zeolites or montmorillonites in the presence of alkaline (pH approx. = 12) cement or mortar and recrystallization to form Al substituted tobermorite. Cesium sorption measurements in 0.01N CaCl2 on the reaction products revealed that selective Cs sorption increased in most cases, even though little or none of the original zeolites and montmorillonites remained in the products. For example, Cs sorption K/sub d/ (mL/g) increased from 80 in the untreated mortar + Ca montmorillonite mixture to 1700 in the interaction product which is Al substituted tobermorite. Thus, we discover here that Al substituted tobermorite has good selectivity for Cs

  13. The chemical evolution of Kurnub Group paleowater in the Sinai-Negev province-a mass balance approach

    International Nuclear Information System (INIS)

    The chemical evolution of the Kurnub Group paleowater was studied starting from rainwater in recharge areas of the Sinai and along groundwater flowpaths leading to the natural outlets of this regional aquifer. This was achieved by investigating the chemical composition of groundwater, ionic ratios, degrees of saturation with common mineral species, normative analysis of dissolved salts and by modeling of rock/water interaction and mixing processes occurring along groundwater flow paths. The initial groundwater composition used is from the Nakhel well in Sinai. It evolves from desert rainwater percolating through typical Kurnub Group lithology in Sinai. This rainwater dissolves mainly gypsum, halite and dolomite together with smaller amounts of marine aerosol and K-feldspar. At the same time it precipitates calcite, SiO2, smectite and degasses CO2. Between the area of Nakhel and the northern Negev the chemistry of Kurnub Group waters is influenced by dissolution of halite and lesser amounts of gypsum of surficial origin in recharge areas, small amounts of feldspars and of dolomite cement in sandstones eroded from the Arabo-Nubian igneous massif of Sinai and organic degradation-derived CO2. Concomitantly, there is precipitation of calcite, smectite, SiO2 and probably analcime characteristic of sediments in continental closed basins. North of the Negev, the Kurnub Group fluids are diluted and altered by mixing with Judea Group aquifer groundwaters. On the E there is mixing with residual brines from the water body ancestral to the Dead Sea, prior to discharge into the Arava valley. Rock/water interaction indicated by NETPATH and PHREEQC modeling is in agreement with lithology and facies changes previously observed in the Kurnub Group sequence. (Copyright (c) 1998 Elsevier Science B.V., Amsterdam. All rights reserved.)

  14. Preferential Treatment: Interaction Between Amino Acids and Minerals

    Science.gov (United States)

    Crapster-Pregont, E. J.; Cleaves, H. J.; Hazen, R. M.

    2008-12-01

    Amino acids are the building blocks of proteins and are important for some models of the origin of life. Polymerization of amino acids from dilute solution is unlikely without a scaffold or catalyst. The surfaces of early Earth minerals are the most likely candidates for this role. The surface adsorption behavior of 12 amino acids (L-alanine, L-serine, L-aspartic acid, L-proline, L- phenylalanine, L-valine, L-arginine, d-amino valeric acid, glycine, L-lysine, L-isoleucine, and B-alanine) on 21 minerals (quartz, calcite, enstatite, illite, olivine, pyrrhotite, pyrite, alkali basalt, albite, analcime, chlorite, barite, hydroxyl apatite, hematite, magnetite, aluminum hydroxide, kaolin, silica gel, corundum, rutile, and montmorillonite) was determined via batch adsorption experiments. Absorption was determined for concentrations between 10-4M and 10-6M in the presence of 0.1M NaCl, and between pH values of 3 and 9 at 25 degrees C. The equilibrated solutions were centrifuged, filtered, derivatized using a fluorescent amino group tag (dansyl-chloride) and analyzed by HPLC. Adsorption was standardized using BET surface area measurements for each mineral to give the number of mols of each amino acid adsorbed per square meter for each mineral. The results indicate an enormous difference in the adsorption of amino acids between minerals, along with major differences in the adsorption of individual amino acids on the same mineral surface. There is also a change in the absorbance of amino acids as the pH changes. Many previous studies of amino acid concentration and catalysis by minerals have used clay minerals because of their high surface areas, however, this data suggests that the surfaces of minerals such as calcite, quartz and pyrite have even higher affinities for amino acids. The results suggest mineral surfaces that could be optimal locations for the polymerization of molecules linked to the origin of life.

  15. Depositional conditions of the coal-bearing Hirka Formation beneath Late Miocene explosive volcanic products in NW central Anatolia, Turkey

    Indian Academy of Sciences (India)

    Mehmet Şener

    2007-04-01

    This work focuses on the relationship between the coal deposition and explosive volcanism of the Miocene basin, NW central Anatolia, Turkey. The coal-bearing Hirka Formation was deposited over the Galatian Andesitic Complex and/or massive lagoonal environments during the Miocene. The investigated lignite is a high ash (from 32 to 58%) and sulphur (from 1.43 to 3.03%) lignite which is petrographically characterised by a high humunite content. The mineral matter of the studied lignite samples is made up of mainly clay minerals (illite–smectite and kaolinite), plagioclase and quartz in Bolu coal field, clay minerals (illite–smectite, smectite and illite), quartz, calcite, plagioclase and gypsum in Seben coal field, quartz, K-feldspar, plagioclase and clay minerals (kaolinite and illite) in Kıbrıscık, and dolomite, quartz, clinoptilolite, opal CT and gypsum in C¸ amlıdere coal field. The differences in these four types of lignite with specific mineralogical patterns may be due to the explosive volcanic events and depositional conditions which changed from one coal field to the others. There is a zonation from SW to SE in the studied area for zeolites such as Opal CT+smectite-clinoptilolite-analcime-K-feldspar. Carbonate minerals are commonly calcite in Seben and Kıbrıscık coal fields. In Bolu, coal samples are devoid of calcite and dolomite. These analyses show that there is an increase in the amount of Mg and a decrease in the amount of Na from the northwestern part to the southern part in the study area.

  16. Synthesis of zeolites from boiler fly ash: physical, chemical and mineralogical characterization; Sintese de zeolitas a partir de cinza volante de caldeiras: caracterizacao fisica, quimica e mineralogica

    Energy Technology Data Exchange (ETDEWEB)

    Rocha Junior, C.A.F.; Santos, S.C.A.; Souza, C.A.G., E-mail: augustorocha2@gmail.com [Programa de Pos Graduacao em Engenharia Quimica (PPEQ-UFPA), Belem, PA (Brazil); Angelica, R.S.; Neves, R.F. [Programa de Pos-Graduacao em Geologia e Geoquimica, Instituto de Geociencias (PPGG-IG-UFPA), Ananindeua, PA (Brazil)

    2012-01-15

    Along the years, worldwide industrial development has causing a growing generation of residues, bringing potentials environmental problems. A study of the characteristics of these wastes, as well as the development of techniques for their use in new processes becomes indispensable for the environment preservation. The main purpose of this work is to evaluate the possible use of two important industrial residues from the Amazon region for zeolite synthesis: (a) the fly ash (particle size < 100 {mu}m) that comes from burning of mineral coal in boiler; and (b) the micro silica, a by-product of the reaction between quartz and coal in the production of metallic silicon and alloys iron-silicon.The following chemical, physical and mineralogical characterization methods were carried out: X-ray diffractometry, X-ray fluorescence, scanning electron microscopy, granulometric analysis, differential thermal and thermogravimetric analysis (DTA-TG). The analyses were carried out at the following conditions: 60, 100, 150 and 190 deg C, Na{sub 2}O/Al{sub 2}O{sub 3} molar ratio of 5 and Si/Al molar ratio ranging from 2.12 to 15, and reaction time of 24 h. The results of the fly characterization demonstrate its enormous potential as raw material for the zeolite synthesis. SiO{sub 2} and Al{sub 2}O{sub 3} represent more than 50% of its composition, mineralogical phases defined, low humidity content, low particle size (d{sub 90} < 10 {mu}m), among others. Mineralogical analyses of the synthesized products showed the formation of some zeolite types, as follow: analcime, phillipsite, sodalite, zeolite P and tobermorite. The results show that the mixture fly ash-micro silica in these reaction conditions point to a promising material for zeolite synthesis (author)

  17. Groundwater prospecting for sandstone-type uranium deposits: the merits of mineral-solution equilibria versus single element tracer methods. Volume II

    International Nuclear Information System (INIS)

    This report presents the results of further research on the groundwater geochemistry of 96 well waters in two uraniferous aquifers in Texas and Wyoming, and is a continuation of the work presented by Chatham et al. (1981). In this study variations in concentrations of U, As, Mo, Se and V were compared with the saturation state of the groundwater with respect to mineral phases of these elements known or expected to occur in each area. The non-radiogenic trace elements exhibited strong redox dependence consistent with thermodynamic predictions, but their variations did not pinpoint existing uranium ore bodies, because of a shift in groundwater flow patterns since the time of ore emplacement. Saturation levels of trace element minerals such as realgar, native Se, and molybdenite showed broad anomalies around the ore-bearing areas, similar to patterns found for U minerals by Langmuir and Chatham (1980), and Chatham et al. (1981). The radiogenic elements Ra and Rn showed significant anomalies directly within the ore zones. Helium anomalies were displaced in the direction of groundwater flow, but by their magnitude and areal extent provided strong evidence for the existence of nearby uranium accumulations. Uranium isotope ratios showed no systematic variations within the two aquifers studied. Saturation maps for kaolinite, illite, montmorillonite and the zeolites analcime and clinoptilolite provided 1 to 2 km anomalies around the ore at the Texas site. Saturation values for the gangue minerals pyrite and calcite defined the redox interface and often suggested the position of probable uranium mineralization. When properly used, the groundwater geochemical concepts for exploration can accurately pinpoint uranium mineralization at a fraction of the cost of conventional methods that involve test drilling and geophysical and core logging

  18. Why is Dawsonite Absent in CO2 Charged Reservoirs?

    International Nuclear Information System (INIS)

    Growth of the sodium-aluminium-hydroxy carbonate dawsonite (NaAl(OH)2CO3) after charging saline aquifers with CO2 has been assumed in a plethora of numerical simulations at different mineralogies, aqueous solutions, pressures and temperatures. It appears however that dawsonite is less abundant than expected in natural CO2 storage analogues if we take into account the thermodynamic stability alone. We have mapped the thermodynamic stability of dawsonite relative to mineral phases like albite, kaolinite and analcime from 37 to 200 C and performed closed-system batch kinetic simulations using a new kinetic expression including a nucleation term based on classical nucleation theory, and a growth term that was based on BCF growth theory. Using this rate equation, we have performed a sensitivity study on dawsonite growth on mineralogy, temperature, CO2 pressure, nucleation rate and its dependencies on temperature and affinity, and on the dawsonite precipitation rate coefficient. Simulations with dawsonite growth disabled showed that the maximum over-saturation reached for dawsonite for seawater-like solutions never exceeded 3-4 times over-saturation. The positive effect on dawsonite growth of increasing the CO2 pressure was mostly neutralized by higher acidity. Decreasing the precipitation rate coefficient by 5 orders of magnitude had a limited effect on the onset of significant growth, but the amount of dawsonite formed at the end of the 1 000 years simulated time was only 37% below the high-rate case. Reducing the nucleation rates had similar effects leading to postponed dawsonite growth. Finally, based on thermodynamic considerations and numerical simulations, we suggest that the potential of dawsonite growth is limited to a medium-temperature window framed by a high thermodynamic stability relative to competing mineral phases at low temperatures, but with rapidly diminishing nucleation and growth rates at lower temperatures constrained by energy barriers. (authors)

  19. Reactivity of the cement-bentonite interface with alkaline solutions using transport cells

    Energy Technology Data Exchange (ETDEWEB)

    Fernandez, Raul [Dpto. Quimica Agricola, Geologia y Geoquimica, Facultad de Ciencias, Universidad Autonoma de Madrid, Campus Cantoblanco, 28049 Madrid (Spain); Cuevas, Jaime [Dpto. Quimica Agricola, Geologia y Geoquimica, Facultad de Ciencias, Universidad Autonoma de Madrid, Campus Cantoblanco, 28049 Madrid (Spain)]. E-mail: jaime.cuevas@uam.es; Sanchez, Laura [Dpto. Quimica Agricola, Geologia y Geoquimica, Facultad de Ciencias, Universidad Autonoma de Madrid, Campus Cantoblanco, 28049 Madrid (Spain); Villa, Raquel Vigil de la [Dpto. Quimica Agricola, Geologia y Geoquimica, Facultad de Ciencias, Universidad Autonoma de Madrid, Campus Cantoblanco, 28049 Madrid (Spain); Leguey, Santiago [Dpto. Quimica Agricola, Geologia y Geoquimica, Facultad de Ciencias, Universidad Autonoma de Madrid, Campus Cantoblanco, 28049 Madrid (Spain)

    2006-06-15

    Clayey formations are considered as suitable host rocks to develop a Deep Geological Repository (DGR) for nuclear wastes. A concrete ring, located between the clayey formation and the bentonite barrier, is needed as structural support for the galleries. This material will act as a source of alkaline fluids when the formation's pore water saturates the system. This investigation evaluates the performance of the concrete-bentonite system by means of both geochemical codes and experimental results. A column made of compacted bentonite from La Serrata (Almeria, Spain) (1.4 g/cm{sup 3}, dry density) was held in contact with an ordinary Portland cement (OPC) mortar. Two alkaline solutions (Ca(OH){sub 2} saturated and NaOH 0.25 M) were injected from the mortar's side at 25, 60 and 120 deg. C. The permeability of the system and the effluent fluid composition were determined periodically. Finally, the solid phase was sampled and analyzed after 1 year of treatment. Ca(OH){sub 2} saturated fluids does not alter the mineralogy over the experiment time scale. NaOH fluids produced minor changes at 60-25 deg. C but at 120 deg. C a thin tobermorite layer of 1.5 mm precipitates in the clay aggregate surfaces at the interface. After this layer, analcime nucleates in heterogeneous patches affecting the whole compacted bentonite probe (2 cm thickness). The use of the PHREEQC code thermodynamic approach predicts the mineralogical transformations. However, it is necessary to introduce kinetic laws and to consider the existence of stagnant zones in the model in order to simulate the heterogeneous spatial alteration observed.

  20. Summary of the mineralogy-petrology of tuffs of Yucca Mountain and the secondary-phase thermal stability in tuffs

    International Nuclear Information System (INIS)

    Yucca Mountain is composed of a thick sequence of silicic tuffs that are quite variable in degree of welding, alteration, and zeolitization. Tuff units above the water table are commonly devitrified or still vitric, with the exception of the zeolitized Pah Canyon Member in USW-G2. The devitrified tuffs above the water table commonly contain alkali feldspar, quartz, tridymite, and cristobalite, with minor smectite. The vitric tuffs are partly to wholly altered to sodium-calcium-saturated smectite. Below the water table are generally densely welded nonzeolitized tuffs and less densely welded zeolite-containing tuffs. The specific mineral assemblage present in Yucca Mountain tuffs has important implications in choosing a repository. The secondary phases clinoptilolite, mordenite, and smectite are very important because of their large cation sorption capacities. However, whereas densely welded tuffs containing no zeolite or glass are resistant to heating and do not dehydrate significantly, zeolitized, vitric, and smectite-containing horizons are very sensitive to minor increases in temperature. Smectites are particularly sensitive to changes in water vapor pressure and temperature, and temperature increases can lead to water evolution and large volume reductions. Similarly, clinoptilolite and mordenite begin to dehydrate below 1000C, resulting in volume decreases. The exact effect of temperature on vitric tuffs is unclear. Under hydrothermal conditions the smectites gradually transform to nonexpanding, low sorption capacity illites, and there is evidence that this reaction has occurred in the deeper portions of USW-G2. Clinoptilolite transforms under hydrothermal conditions to analcime plus quartz with a concomitant volume decrease and water evolution. Again, there is evidence of this reaction occurring in Yucca Mountain tuffs at 80 to 1000C

  1. Petrologic and isotopic data from the Cretaceous (Campanian) Blackhawk Formation and Star Point Sandstone (Mesaverde Group), Wasatch Plateau, Utah

    Science.gov (United States)

    Fishman, Neil S.; Turner, Christine E.; Peterson, Fred

    2013-01-01

    The presence of discrete minerals associated with coal—whether (1) detrital or authigenic constituents of the coals or in thin mudstone or siltstone units interbedded with coals, or (2) authigenic phases that formed along cleats—might influence its utilization as an energy resource. The build-up of sintered ash deposits on the surfaces of heat exchangers in coal-fired power plants, due to the alteration of minerals during combustion of the coal, can seriously affect the functioning of the boiler and enhance corrosion of combustion equipment. In particular, the presence of sodium in coals has been considered a key factor in the fouling of boilers; however, other elements (such as calcium or magnesium) and the amount of discrete minerals burned with coal can also play a significant role in the inefficiency of and damage to boilers. Previous studies of the quality of coals in the Cretaceous (Campanian) Blackhawk Formation of the Wasatch Plateau, Utah, revealed that the sodium content of the coals varied across the region. To better understand the origin and distribution of sodium in these coals, petrologic studies were undertaken within a sedimentological framework to evaluate the timing and geochemical constraints on the emplacement of sodium-bearing minerals, particularly analcime, which previously had been identified in coals in the Blackhawk Formation. Further, the study was broadened to include not just coals in the Blackhawk Formation from various localities across the Wasatch Plateau, but also sandstones interbedded with the coals as well as sandstones in the underlying Star Point Sandstone. The alteration history of the sandstones in both formations was considered a key component of this study because it records the nature and timing of fluids passing through them and the associated precipitation of sodium-bearing minerals; thus, the alteration history could place constraints on the distribution and timing of sodium mineralization in the interbedded or

  2. Relation between sedimentary framework and hydrogeology in the Guarani Aquifer System in São Paulo state, Brazil

    Science.gov (United States)

    Hirata, Ricardo; Gesicki, Ana; Sracek, Ondra; Bertolo, Reginaldo; Giannini, Paulo César; Aravena, Ramón

    2011-04-01

    This paper presents the results of a new investigation of the Guarani Aquifer System (SAG) in São Paulo state. New data were acquired about sedimentary framework, flow pattern, and hydrogeochemistry. The flow direction in the north of the state is towards the southwest and not towards the west as expected previously. This is linked to the absence of SAG outcrop in the northeast of São Paulo state. Both the underlying Pirambóia Formation and the overlying Botucatu Formation possess high porosity (18.9% and 19.5%, respectively), which was not modified significantly by diagenetic changes. Investigation of sediments confirmed a zone of chalcedony cement close to the SAG outcrop and a zone of calcite cement in the deep confined zone. The main events in the SAG post-sedimentary history were: (1) adhesion of ferrugineous coatings on grains, (2) infiltration of clays in eodiagenetic stage, (3) regeneration of coatings with formation of smectites, (4) authigenic overgrowth of quartz and K-feldspar in advanced eodiagenetic stage, (5) bitumen cementation of Pirambóia Formation in mesodiagenetic stage, (6) cementation by calcite in mesodiagenetic and telodiagenetic stages in Pirambóia Formation, (7) formation of secondary porosity by dissolution of unstable minerals after appearance of hydraulic gradient and penetration of the meteoric water caused by the uplift of the Serra do Mar coastal range in the Late Cretaceous, (8) authigenesis of kaolinite and amorphous silica in unconfined zone of the SAG and cation exchange coupled with the dissolution of calcite at the transition between unconfined and confined zone, and (9) authigenesis of analcime in the confined SAG zone. The last two processes are still under operation. The deep zone of the SAG comprises an alkaline pH, Na-HCO 3 groundwater type with old water and enriched δ 13C values (groundwater type with young water and depleted δ 13C values (>-18.8) close to the SAG outcrop. This is consistent with a conceptual

  3. Oil shales, evaporites and ore deposits

    Science.gov (United States)

    Eugster, Hans P.

    1985-03-01

    elevated temperatures and with carbonates as principal host rocks. The Pine Point deposits are cited for their close association with evaporites. Alkaline, metal-rich brines are postulated for the HYC deposit of McArthur River, Australia. Such brines are known from the Green River Formation and deposits formed from such brines constitute the GRT class. They can be recognized by the presence of Magadi-type cherts and zeolite-analcime-K-spar tuffs. The Cu-Co ore bodies of Outokumpu, Finland, might also belong to this type. A new classification of sedimentary ore deposits is proposed, based on their geochemical environment. KST and MVT are formed from acid ore fluids, while GRT and CT (Creede type) are derived from basic ore fluids. pH of the fluids is best evaluated not from the ores themselves, but from their effect on the host-rocks.

  4. Composition and diagenetic processes of sandstone and tuff deposits of the Cenomanian Cardiel Formation, Cardiel Lake area, province of Santa Cruz

    Directory of Open Access Journals (Sweden)

    R.R. Andreis

    2007-06-01

    Full Text Available The Cardiel Formation (Cenomanian, around 200 m in thickness in the studied area, includes different types of volcaniclastic deposits, mainly represented by fine tuffs and massive bentonites, and subordinated epiclastics such as lithic sandstones of yellowish-brown, dusky yellow, or light olive hues, siltstones and claystones. Reddened paleosols with some small axial roots and weak prismatic structures appear on top of siltstones, tuffs and bentonites. Tufites and tuffs contain the same neovolcanic components, abundant glass shards and minor pumices. Different types of glass shards can be differentiated whitin this unit, whereas pumice fragments are represented by different vesicular varieties. Vitreous tuffaceous clasts are abundant in the tufites. Almost all samples contain not only diagenetically-derived, but also pedogenetically-infiltrated montmorillonite, as well as zeolites. Predominant Ca-Na-K clinoptilolite (Si/Al>4 and minor analcime (Si/Al near 3 were identified. Smectite and clinoptilolite may either replace glass-shards or pumices, or fill pore spaces, whereas smectite also appears as thin cutans. The sequence of diagenetic processes includes the conversion (hydrolysis of glass to smectite, and later to zeolites. Furthermore, zeolites preceded calcite growth (sometimes replacing glass-shards or pumices, which in turn, formed prior to pervading ferric oxides-hydroxides. The vertical distribution of zeolites can be explained taking into account the presence of percolating waters in an open hydrologic system. The zeolite content throughout the whole profile links the mineralogical association observed within the sediments of the Cardiel Formation to the clinoptilolite zone. Paleoenvironmental reconstructions for the Cardiel Formation point out to tidal currents taking place in wide lagoons; tuffaceous and bentonitic deposits covered those ancient lagoons forming wide, flat plains on which paleosols developed. Paleocurrents measured on

  5. Natural zeolites filling amygdales and veins in basalts from the British Tertiary Igneous Province on the Isle of Skye, Scotland

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    Triana J M

    2012-10-01

    Full Text Available

    ABSTRACT

    Natural zeolites filling amygdales and veins in tertiary basaltic host rocks on the Isle of Skye (NW Scotland have been studied in some detail by transmitted light microscopy, scanning electron microscopy and X-ray diffraction techniques . The zeolites and associated minerals so identified in order of their relative time of formation from early to late were nontronite, amorphous silica phases, carbonate phases, chabazite, phillipsite, wairakite, thomsonite, analcime, natrolite and stilbite-type minerals . Zeolite formation in the Skye basalts began with low Si/Al ratio Na zeolites and a gradual increase in Ca content and Si/Al ratio, ending up as Ca zeolites . They were probably formed as a consequence of late-stage hydrothermal activity, although, locally, contact metamorphism may control the process of zeolite formation

    RESUMEN

    Las zeolitas naturales como relleno en amígdalas y venas que ocurren en rocas basálticas Terciarias de la Isla de Skye (NW Escocia han sido estudiadas en detalle por técnicas de microscopía de luz transmitida, microscopía electrónica de barrido y difracción de rayos X. Las zeolitas y los minerales asociados identificados, en orden de su tiempo relativo de formación, son nontronita, fases de sílice amorfa, carbonatos, chabazita, filipsita, wairakita, thomsonita, analcima, natrolita y minerales tipo estilbita. La formación de zeolitas en los basaltos de Skye comenzó con una zeolita rica en Na de baja relación Si/Al y con el aumento gradual en el contenido de Ca y Si/Al, terminó con una zeolita rica en Ca Estas probablemente se formaron como consecuencia de una actividad hidrotermal tardía, aunque localmente un metamorfismo de contacto pudo controlar el proceso de formación de las zeolitas

  6. Development of analytical technique of alteration minerals formed in bentonite by the reaction with alkaline solution

    International Nuclear Information System (INIS)

    Bentonite will be used as a buffer material, according to the TRU waste disposal concept in Japan, to retard radionuclides migration, to restrict seepage of ground water and to filtrate colloids. One of the concern about the buffer material is the long term alteration of bentonite with cementitious material. Long term alteration of bentonite-based materials with alkaline solution has been studied by means of analytical approaches, coupling mass transport and chemical reactions, which suggest changes in various properties of buffer materials. Long term performance assessment of engineered barriers under disposal conditions is important to achieve a reasonable design, eliminating excessive conservatism in the safety assessment. Therefore it is essential for improving the reliance of the performance assessment to verify the analytical results through alteration tests and/or natural analogue. The geochemical analyses indicate that major alteration reactions involve dissolution of portlandite, chalcedony and montmorillonite and formation of C-S-H gel and analcime at the interface between cement and bentonite. However, in the alteration tests assuming interaction between bentonite and cement, secondary minerals due to alteration under the expected condition for geological disposal (equilibrated water with cement at low liquid/solid ratio) had not been observed, though the alteration was observed under accelerated hyper alkaline and high temperatures conditions. The reason is considered that it is difficult to analyze C-S-H gel formed at the interface because of its small quantity. One of examples is the Kunigel V1, a potential buffer material in Japan, which consists of montmorillonite, chalcedony, plagioclase, and calcite. In the XRD analysis of the Kunigel V 1, the locations of the primary peak of the calcite and that of the C-S-H gel overlap, which makes identification of small quantity of C-S-H gel formed as a secondary mineral difficult. Thus development of

  7. Experimental Analysis of Impact Glass Alteration

    Science.gov (United States)

    Kalleson, E.; Dypvik, H.; Hellevang, H.

    2011-12-01

    -pyrophylite, saponite, analcime, talc and philippsite. On the Earth, as well as on Mars, additional processes such as surface weathering and postdepositional diagenesis may affect the mineralogical transformations. In this study our primary goal is to demonstrate and explain the formation of phyllosilicates and zeolites from impact melt / glass alteration, during conditions imitating an impact-induced hydrothermal system.

  8. Quantitative kinetic and structural analysis of geopolymers. Part 2. Thermodynamics of sodium silicate activation of metakaolin

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Zuhua, E-mail: zuhua.zhang2@usq.edu.au [Faculty of Engineering and Surveying, University of Southern Queensland, Toowoomba, QLD 4350 (Australia); Provis, John L. [Department of Materials Science and Engineering, The University of Sheffield, Mappin St, Sheffield S1 3JD (United Kingdom); Wang, Hao; Bullen, Frank [Faculty of Engineering and Surveying, University of Southern Queensland, Toowoomba, QLD 4350 (Australia); Reid, Andrew [Halok Pty Ltd. West End, QLD 4101 (Australia)

    2013-08-10

    Highlights: • ICC is confirmed again to be useful in studying the thermodynamics of geopolymerization. • Na-silicate activation of metakaolin at 25 °C processes an extent of ∼0.20, far from the final structure. • Na/Al has a more pronounced influence on the reaction extent of metakaolin than do temperature and Si/Al ratio. • ICC is expected to be a powerful technique in quantifying the reactivity of various aluminosilicate precursors. - Abstract: The paper describes the outcomes of a study using isothermal conduction calorimetry (ICC) to characterize the geopolymerization kinetics of metakaolin activated with sodium silicate. Two exothermic peaks are observed in the calorimetric curves for all systems reacting within the temperature range 20–40 °C. The peaks are assigned to the dissolution of metakaolin, and the formation of geopolymeric gels with disordered structure, respectively. Compared with the use of NaOH solution to activate metakaolin, the presence of soluble silicate in the activator hinders the reorganization of the local structure of geopolymeric gels and also suppresses the formation of zeolites or zeolite precursors. The ICC data are used via a thermochemical model to quantify the reaction kinetics of geopolymerization, by assuming that the geopolymeric gels have an analcime-like local structure and taking into account the speciation of the silicate monomers and dimers in the activator. Decreasing the modulus from 1.6 to 1.0 increases the fractional reaction extent from 0.12 to 0.26 after 72 h at 25 °C. When the modulus is 1.2, increasing the reaction temperature from 20 °C to 35 °C results in an improved reaction extent from 0.24 to 0.35. The rapid polymerization that occurs at 40 °C appears to hinder the further reaction of MK and consequently results in a lower reaction extent than at 35 °C. Combined with the findings from previous analysis of systems where NaOH was used to activate MK, the concentration of available Na

  9. Supercritical carbon dioxide and sulfur in the Madison Limestone: A natural analog in southwest Wyoming for geologic carbon-sulfur co-sequestration

    Science.gov (United States)

    Kaszuba, John P.; Navarre-Sitchler, Alexis; Thyne, Geoffrey; Chopping, Curtis; Meuzelaar, Tom

    2011-09-01

    The Madison Limestone on the Moxa Arch, southwest Wyoming, USA contains large volumes (65-95%) of supercritical CO 2 that it has stored naturally for 50 million years. This reservoir also contains supercritical H 2S, aqueous sulfur complexes (SO 42- and HS -), and sulfur-bearing minerals (anhydrite and pyrite). Although SO 2 is not present, these sulfur-bearing phases are known products of SO 2 disproportionation in other water-rock systems. The natural co-occurrence of SO 42-, S 2-, supercritical CO 2 and brine affords the opportunity to evaluate the fate of a carbon-sulfur co-sequestration scenario. Mineralogic data was obtained from drill core and aqueous geochemical data from wells outside and within the current supercritical CO 2-sulfur-brine-rock system. In addition to dolomite, calcite, and accessory sulfur-bearing minerals, the Madison Limestone contains accessory quartz and the aluminum-bearing minerals feldspar, illite, and analcime. Dawsonite (NaAlCO 3(OH) 2), predicted as an important carbon sink in sequestration modeling studies, is not present. After confirming equilibrium conditions for the Madison Limestone system, reaction path models were constructed with initial conditions based on data from outside the reservoir. Addition of supercritical CO 2 to the Madison Limestone was simulated and the results compared to data from inside the reservoir. The model accurately predicts the observed mineralogy and captures the fundamental changes expected in a Madison Limestone-brine system into which CO 2 is added. pH decreases from 5.7 to 4.5 at 90 °C and to 4.0 at 110 °C, as expected from dissolution of supercritical CO 2, creation of carbonic acid, and buffering by the carbonate rock. The calculated redox potential increases by 0.1 V at 90 °C and 0.15 V at 110 °C due to equilibrium among CO 2, anhydrite, and pyrite. Final calculated Eh and pH match conditions for the co-existing sulfur phases present in produced waters and core from within the reservoir

  10. Chemical evolution of coal mine drainage in a non-acid producing environment, Wasatch Plateau, Utah, USA

    Science.gov (United States)

    Mayo, A. L.; Petersen, E. C.; Kravits, C.

    2000-09-01

    drainage relative to the TDS of roof-drip water. Pyrite oxidation does not result in acid drainage because of the buffering effect of abundant carbonate minerals. Dissolution of gypsum, both native and gypsum dust previously used as rock dust, is also a significant contributor of SO 42-. Ion exchange of Ca 2+ on the sodium zeolite analcime, which occurs in the coal, accounts for an increase in Na + concentrations. Oxidation of fugitive longwall emulsion fluid produces abundant CO 2(g) some of which indirectly affect the TDS of mine drainage.

  11. Why is Dawsonite Absent in CO2 Charged Reservoirs? Pourquoi la dawsonite est-elle absente des réservoirs chargés en CO2 ?

    Directory of Open Access Journals (Sweden)

    Hellevang H.

    2011-03-01

    Full Text Available Growth of the sodiumaluminium-hydroxy carbonate dawsonite (NaAl(OH2CO3 after charging saline aquifers with CO2 has been assumed in a plethora of numerical simulations at different mineralogies, aqueous solutions, pressures and temperatures. It appears however that dawsonite is less abundant than expected in natural CO2 storage analogues if we take into account the thermodynamic stability alone. We have mapped the thermodynamic stability of dawsonite relative to mineral phases like albite, kaolinite and analcime from 37° to 200°C and performed closed-system batch kinetic simulations using a new kinetic expression including a nucleation term based on classical nucleation theory, and a growth term that was based on BCF growth theory. Using this rate equation, we have performed a sensitivity study on dawsonite growth on mineralogy, temperature, CO2 pressure, nucleation rate and its dependencies on temperature and affinity, and on the dawsonite precipitation rate coefficient. Simulations with dawsonite growth disabled showed that the maximum oversaturation reached for dawsonite for seawater-like solutions never exceeded 3-4 times oversaturation. The positive effect on dawsonite growth of increasing the CO2 pressure was mostly neutralized by higher acidity. Decreasing the precipitation rate coefficient by 5 orders of magnitude had a limited effect on the onset of significant growth, but the amount of dawsonite formed at the end of the 1 000 years simulated time was only 37% below the high-rate case. Reducing the nucleation rates had similar effects leading to postponed dawsonite growth. Finally, based on thermodynamic considerations and numerical simulations, we suggest that the potential of dawsonite growth is limited to a medium-temperature window framed by a high thermodynamic stability relative to competing mineral phases at low temperatures, but with rapidly diminishing nucleation and growth rates at lower temperatures constrained by energy

  12. Petrology of continental pyroclastic and epiclastic sequences in the Chubut Group (Cretaceous: Los Altares-Las Plumas area, Chubut, Patagonia Argentina

    Directory of Open Access Journals (Sweden)

    Marcelo Manassero

    2000-07-01

    The volcaniclastic successions of the Cerro Barcino Formation (Chubut Group, of Aptian-Cenomanian age, crop out on both margins of the Chubut River with a thickness of 200 m. The Middle Member Cerro Castaño (syneruptive, 90 m and the Upper Member, Las Plumas (intereruptive, 110 m are described on the basis of photogeological mapping, sections, and mineralogical, petrographical and geochemical analysis. Paleocurrents are directed to the northeast (Cerro Castaño or north (Las Plumas. An erosive boundary, located at the base of the Las Plumas Member, is reported for the first time in this contribution The pyroclastic rocks are composed, of planar, curviplanar, branching, Y-shaped shards and fibrous pumice fragments. The volcanogenic sedimentary deposits also include, vitric fragments with hematitic pigmentation (Las Plumas. Due to diagenetic processes, the glass fragments are replaced by clay minerals (smectites and scarce illite and zeolites which also appear as cementing material. Within the Cerro Castaño Member, analcime prevails assembled with less clinoptilolite, while in the Las Plumas Member, the abundant clinoptilolite is assembled with scarce analcime and mordenite. Pyroclastic sediments (ash-fall covered extended flat or slightly undulated plains, where discrete sandy rivers flowed. The presence of gravels and sandstones at the base of the Las Plumas Member and wide and shallow braided river channels are associated to tectonic events and seasonability. Eruptions were highly explosive derived from viscous and volatile-rich magmas. The abundance of fine planar and cuspate shards in the tuff suggest that the explosive center was located approximately 500 km probably to the west

  13. Thermodynamic and Kinetic Aspects of the Dissolution of Quartz-Kaolinite Mixtures by Alkalis Aspects thermodynamiques et cinétiques de la dissolution des mélanges quartz-kaolinite par les alcalis

    Directory of Open Access Journals (Sweden)

    Labrid J.

    2006-11-01

    de réduire la tension interfaciale entre l'eau et l'huile brute, grâce à la formation in situ de tensio-actifs résultant de la réaction de l'additif alcalin avec certains constituants de l'huile. La technique s'est depuis largement améliorée avec l'emploi des alcalins en combinaison avec d'autres additifs chimiques tels que les polymères et les tensio-actifs. Dans tous les cas, un point critique réside dans le transport de l'agent alcalin du puits d'injection au puits de production. Divers processus contribuent en effet à réduire la quantité d'additif réellement disponible. Parmi ceux-ci, figure la consommation de l'alcali par dissolution de certains minéraux de la roche réservoir. Ce problème est abordé en étudiant tout d'abord les conditions de dissolution d'un sable supposé représenter la matrice quartzeuse d'une roche gréseuse naturelle. Nous avons adopté un schéma cinétique fondé sur l'adsorption d'acide silicique à la surface du quartz : l'étape déterminante de la dissolution est l'expulsion d'un motif silicique du réseau cristallin, l'acide silicique adsorbé bloquant la dissolution. La concentration en silicium solubilisé au cours du temps est calculée à l'aide d'un modèle numérique qui utilise les paramètres cinétiques déterminés de manière expérimentale. Il est connu que l'adsorption d'aluminium à la surface du quartz réduit de manière considérable sa dissolution. Dans une roche gréseuse, l'aluminium provient de la dissolution des argiles et des feldspaths. Les essais de dissolution effectués avec des solutions alcalines contenant de l'aluminium ont montré que celui-ci s'adsorbait à la surface solide et réduisait ainsi les vitesses initiale et courante de dissolution. Ces essais ont aussi permis de mettre en évidence la formation et la précipitation, au cours de la dissolution, d'un aluminosilicate : l'analcime AISi2O6Na. H2O. Son produit de solubilité a pu être déterminé par analyse des effluents. L

  14. Volcanic facies and mineral chemistry of Tertiary volcanics in the northern part of the Eastern Pontides, northeast Turkey: implications for pre-eruptive crystallization conditions and magma chamber processes

    Science.gov (United States)

    Yücel, Cem; Arslan, Mehmet; Temizel, İrfan; Abdioğlu, Emel

    2014-06-01

    Tertiary volcanics in the northern zone of the Eastern Pontides are characterized by subaerial and shallow-subaqueous facieses, and are divided into three volcanic suites: Eocene aged (1) basalt-trachybasalt-basaltic trachyandesite (BTB) and (2) trachyte-trachyandesite (TT), and Miocene aged (3) basanite-tephrite (BT) suites. Clinopyroxene is a common phase in all three volcanic suites, and has different compositions with Mg# varying from 0.57 to 0.91 in BTB suite and 0.57-0.84 in TT suite to 0.65-0.90 in BT suite. Feldspars in all suites generally exhibit wide range of compositions from sanidine to albite or anorthite and have weak normal and reverse compositional zoning. Olivines in BTB and BT suites have Fo60-92. Hornblendes in BTB, TT and BT suites are commonly magnesio-hastingsite and rare pargasite in composition (Mg#: 0.67-0.90). Brown mica is mainly phlogopite with Mg# ranging from 0.56 to 0.92 in the BTB suite, 0.59-0.84 in the TT suite, and 0.75-0.93 in the BT suite. Analcime is present only in the BT suite rocks. Fe-Ti oxides in all suites are mainly composed of magnetite and titanomagnetite. Textural petrographic and mineral chemical data suggest that magmas had undergone hydrous and anhydrous crystallizations in deep-, mid-, and shallow-crustal magma chambers. Clinopyroxene thermobarometric calculations show that Eocene magma chambers were characterized by temperature ranging from 1,100 to 1,244 °C and pressure ranging from 1.84 to 5.39 kbar. Similarly, the Miocene magma chambers were characterized by temperature ranging from 1,119 to 1,146 °C and pressure ranging from 4.23 to 4.93 kbar. Hornblende thermobarometry, oxygen fugacity, and hygrometer reveal that the crystallization temperature of Eocene volcanics range from 956 to 959 °C at pressure ranging from 6.49 to 6.52 kbar. Eocene volcanics were characterized by water content ranging from 7.83 to 8.57 wt.% and oxygen fugacity of 10-9.36 to 10-9.46 (ΔNNO+2). Miocene volcanics had crystallization

  15. Experimental Study on Alteration of Highly Compacted Bentonite -Dissolution Rate of Montmorillonite and the Effect on Permeability

    International Nuclear Information System (INIS)

    Case 3 was not. After measuring the density, they were dried and loosened for the solid analyses. The XRD charts around the second strong peak of analcime are shown in Fig.5. Using AFM, the one-hundred crystal particles of montmorillonite in each part were randomly chosen and their Basal Surface Area and Edge Surface Area were measured. Based on statistical study using the AFM measurements, it is shown that the upper bound of dissolution rate of montmorillonite in the compacted bentonite is 9.7x10-13 mol/m2/sec in significance level of 95%. The value is less than one thirtieth of the Sato equation (Sato et al., 2004) as shown in Fig.6. That is because the pore solution of compacted bentonite is close to equilibrium for montmorillonite dissolution. The values of hydraulic conductivity of compacted bentonite in this study are plot against montmorillonite partial density as shown in Fig.7, which are approximately one tenth of the estimates by the equation of Ito and Mihara (2005). (authors)

  16. Geochemical Modeling of ILAW Lysimeter Water Extracts

    Energy Technology Data Exchange (ETDEWEB)

    Cantrell, Kirk J.

    2014-12-22

    Geochemical modeling results of water extracts from simulated immobilized low-activity waste (ILAW) glasses, placed in lysimeters for eight years suggest that the secondary phase reaction network developed using product consistency test (PCT) results at 90°C may need to be modified for field conditions. For sediment samples that had been collected from near the glass samples, the impact of glass corrosion could be readily observed based upon the pH of their water extracts. For unimpacted sediments the pH ranged from 7.88 to 8.11 with an average of 8.04. Sediments that had observable impacts from glass corrosion exhibited elevated pH values (as high as 9.97). For lysimeter sediment samples that appear to have been impacted by glass corrosion to the greatest extent, saturation indices determined for analcime, calcite, and chalcedony in the 1:1 water extracts were near equilibrium and were consistent with the secondary phase reaction network developed using PCT results at 90°C. Fe(OH)3(s) also appears to be essentially at equilibrium in extracts impacted by glass corrosion, but with a solubility product (log Ksp) that is approximately 2.13 units lower than that used in the secondary phase reaction network developed using PCT results at 90°C. The solubilities of TiO2(am) and ZrO2(am) also appear to be much lower than that assumed in the secondary phase reaction network developed using PCT results at 90°C. The extent that the solubility of TiO2(am) and ZrO2(am) were reduced relative to that assumed in the secondary phase reaction network developed using PCT results at 90°C could not be quantified because the concentrations of Ti and Zr in the extracts were below the estimated quantification limit. Gibbsite was consistently highly oversaturated in the extract while dawsonite was at or near equilibrium. This suggests that dawsonite might be a more suitable phase for the secondary phase reaction network than gibbsite under field conditions. This may be due to the

  17. Native sulfur, sulfates and sulfides from the active Campi Flegrei volcano (southern Italy): Genetic environments and degassing dynamics revealed by mineralogy and isotope geochemistry

    Science.gov (United States)

    Piochi, Monica; Mormone, Angela; Balassone, Giuseppina; Strauss, Harald; Troise, Claudia; De Natale, Giuseppe

    2015-10-01

    We investigated sulfur-bearing minerals from the Campi Flegrei caldera, southern Italy, in relation to the increase of hydrothermal activity phenomena since 2006, aimed at providing insights into the volcanic system dynamics. Mineral encrustations and muds were sampled between 2013 and 2015 at the long-standing degassing crater of the Solfatara tuff cone and its recently restless north-eastern Pisciarelli slope. Deep-seated sulfides were further separated from two drill cores (AGIP's Mofete boreholes: 1500 m and 2695 m depth). The mineral assemblage and texture of sampled encrustations were determined by X-ray diffraction, optical and scanning electron microscopy and X-ray microanalysis by energy dispersive spectrometry. Native sulfur and alunite dominate among the newly formed mineral phases. Other minerals are mostly alunogen, and locally pickeringite, potassium alum, hematite and pyrite. Mereiterite and amarillite sporadically occur. The mud pools are rich in gypsum, potassium alum and pyrite. Quartz and argillic phases, locally with analcime, are dispersed in the outcropping rocks. δ34S values were determined for shallow subsurface native sulfur (- 5.5 to 0.0‰) and alunite (- 1.7 to - 0.2‰), as well as for the deep-seated pyrite (3.3 to 7.4‰ in the depth range:1500-2695 m). δ18O values were measured for shallow native alunite (4.2 to 7.0‰). Pisciarelli alunite was finally analyzed for its 87Sr/86Sr ratio and 143Nd/144Nd ratios (0.707517 ± 6 and 0.512459 ± 6, respectively). Textural and isotopic data constrain the genesis of alunite at the expense of K-feldspars through rock alteration by hydrothermal fluids. We suggest that the caldera is a low-sulfidation system hosting acid-sulfate deposits in its active degassing area. The acid-sulfate environment developed on an argillitic facies that thins outwards and is characteristic for steam-heated and magmatic-steam environments. These environments developed in relation to the fractured settings that

  18. Identification of Some Zeolite Group Minerals by Application of Artificial Neural Network and Decision Tree Algorithm Based on SEM-EDS Data

    Science.gov (United States)

    Akkaş, Efe; Evren Çubukçu, H.; Akin, Lutfiye; Erkut, Volkan; Yurdakul, Yasin; Karayigit, Ali Ihsan

    2016-04-01

    Identification of zeolite group minerals is complicated due to their similar chemical formulas and habits. Although the morphologies of various zeolite crystals can be recognized under Scanning Electron Microscope (SEM), it is relatively more challenging and problematic process to identify zeolites using their mineral chemical data. SEMs integrated with energy dispersive X-ray spectrometers (EDS) provide fast and reliable chemical data of minerals. However, considering elemental similarities of characteristic chemical formulae of zeolite species (e.g. Clinoptilolite ((Na,K,Ca)2 ‑3Al3(Al,Si)2Si13O3612H2O) and Erionite ((Na2,K2,Ca)2Al4Si14O36ṡ15H2O)) EDS data alone does not seem to be sufficient for correct identification. Furthermore, the physical properties of the specimen (e.g. roughness, electrical conductivity) and the applied analytical conditions (e.g. accelerating voltage, beam current, spot size) of the SEM-EDS should be uniform in order to obtain reliable elemental results of minerals having high alkali (Na, K) and H2O (approx. %14-18) contents. This study which was funded by The Scientific and Technological Research Council of Turkey (TUBITAK Project No: 113Y439), aims to construct a database as large as possible for various zeolite minerals and to develop a general prediction model for the identification of zeolite minerals using SEM-EDS data. For this purpose, an artificial neural network and rule based decision tree algorithm were employed. Throughout the analyses, a total of 1850 chemical data were collected from four distinct zeolite species, (Clinoptilolite-Heulandite, Erionite, Analcime and Mordenite) observed in various rocks (e.g. coals, pyroclastics). In order to obtain a representative training data set for each minerals, a selection procedure for reference mineral analyses was applied. During the selection procedure, SEM based crystal morphology data, XRD spectra and re-calculated cationic distribution, obtained by EDS have been used for

  19. Selected durability studies of geopolymer concrete with respect to carbonation, elevated temperature, and microbial induced corrosion

    Science.gov (United States)

    Badar, Mohammad Sufian

    prepared with certain fly ashes exhibited signs of expansion along with cracking and spalling, while GPC prepared with specific class F fly ash showed superior resistance to thermal shock. Microstructural analysis revealed that the resistance of GPC at elevated temperatures was dependent on the type of fly ash used, its particle size distribution, formation of zeolitic phases such as sodalite, analcime and nepheline, and the overall pore structure of the geopolymer concrete. The work indicates that the chemical composition and particle size distribution of the fly ash, type of fly ash (Class C & F) and the geopolymerization process that took place a vital role in the performance of geopolymer concretes in high temperature applications. Microbial Induced Corrosion: Corrosion is a major form of deterioration in concrete structures. According to a report published by the U.S. FHWA 2002, the cost of corrosion in water and wastewater conveyance, and storage and treatment facilities in the U.S. is about $138 billions. A main form of corrosion in wastewater collection systems is Microbial Induced Corrosion (MIC). However, the conditions present in industrial or municipal wastewater pipes, or storage facility are induced by the production of sulfuric acid by biological processes, which cannot be fully mimicked by simple acid corrosion. The present study intends to provide similar conditions inside pipe specimens that mimic a true sewer atmosphere. The experimental setup consisted of three 12" diameter and 30" long concrete pipe specimens, 2 specimens were coated with different formulations of GPC while the third was a control. Both ends of each pipe specimen were sealed to prevent hydrogen sulfide gas from escaping. One pipe was coated with GPC that had a biocide agent entrained. Another pipe specimen was coated with OPC and the 3rd pipe was used as a control and was not coated. Parameters measured can be divided into three groups: general environmental parameters like pH and

  20. Encapsulating Metal Clusters and Acid Sites within Small Voids: Synthetic Strategies and Catalytic Consequences

    Science.gov (United States)

    Goel, Sarika

    The selective encapsulation of metal clusters within zeolites can be used to prepare clusters that are uniform in diameter and to protect them against sintering and contact with feed impurities, while concurrently allowing active sites to select reactants based on their molecular size, thus conferring enzyme-like specificity to chemical catalysis. The apertures in small and medium-pore zeolites preclude the use of post-synthetic protocols to encapsulate the relevant metal precursors because cationic or anionic precursors with their charge-balancing double layer and gaseous complexes cannot diffuse through their windows or channels. We have developed general strategies to encapsulate metal clusters within small-pore zeolites by using metal precursors stabilized by ammonia or organic amine ligands, which stabilize metal precursors against their premature precipitation at the high temperature and pH conditions required for the hydrothermal synthesis of the target zeolite structures and favor interactions between metal precursors and incipient aluminosilicate nuclei during the self-assembly of microporous frameworks. When synthesis temperatures were higher than 400 K, available ligands were unable to prevent the premature precipitation of the metal precursors. In such cases, encapsulation was achieved instead via interzeolite transformations after successfully encapsulating metal precursors or clusters via post-synthesis exchange or ligand protection into parent zeolites and subsequently converting them into the target structures while retaining the encapsulated clusters or precursors. Such strategies led to the successful selective encapsulation of a wide range of metal clusters (Pt, Pd, Ru, Rh, Ir, Re, and Ag) within small-pore (SOD (sodalite), LTA (Linde type A (zeolite A)), GIS (gismondine), and ANA (analcime)) and medium-pore (MFI (ZSM-5)) zeolites. These protocols provide novel and diverse mechanism-based strategies for the design of catalysts with protected

  1. Burovaite-Ca, (Na,K)4Ca2(Ti,Nb)8[Si4O12]4(OH,O)8·12H2O, a new labuntsovite-group mineral species and its place in low-temperature mineral formation in pegmatites of the Khibiny pluton, Kola Peninsula, Russia

    Science.gov (United States)

    Azarova, Yu. V.; Shlyukova, Z. V.; Zolotarev, A. A.; Organova, N. I.

    2009-12-01

    This paper presents data on burovaite-Ca, the first Ti-dominant member of the labuntsovite group with a calcium D-octahedron. The idealized formula of burovaite-Ca is (K,Na)4Ca2(Ti,Nb)8[Si4O12]4(OH,O)8 · 12H2O. The mineral has been found in the hydrothermal zone of aegirine-microcline pegmatite located in khibinite at Mt. Khibinpakhkchorr, the Khibiny pluton, Kola Peninsula, Russia. Radiaxial intergrowths of burovaite-Ca and labuntsovite-Mn associated with lemmleynite-Ba, analcime, and apophyllite have been identified in caverns within microcline. The mean composition of the mineral is as follows, wt %: 3.72 Na2O, 2.76 K2O, 4.22 CaO, 0.47 SrO, 0.23 BaO, 0.01 MnO, 0.30 Fe2O3, 0.14 Al2O3, 42.02 SiO2, 17.30 TiO2, 15.21 Nb2O5, 12.60 H2O (measured); the total is 98.98. Its empirical formula has been calculated on the basis of [(Si,Al)16O48]: {(Na3.10K1.07Ca0.37Sr0.04Ba0.04)4.62}(Ca1.28Zn0.01)1.29(Ti4.97Nb2.56Fe0.08Ta0.02)7.63(Si15.93Al0.07)16O48(OH6.70O0.93)7.63 · 12H2O. The strongest lines in the X-ray powder diffraction pattern of burovaite-Ca ( I-d Å] are as follows: 70-7.08, 40-6.39, 40-4.97, 30-3.92, 40-3.57, 100-3.25, 70-3.11, 50-2.61, 70-2.49, 40-2.15, 50-2.05, 70-1.712, 70-1.577, and 70-1.444. The structure of burovaite-Ca was solved by A.A. Zolotarev, Jr. The mineral is monoclinic, space group C2/ m. The unit-cell dimensions are a = 14.529(3), b = 14.203(3), c = 7.899(1), β = 117.37(1)°, V = 1447.57 Å3. Burovaite-Ca is an isostructural Ti-dominant analogue of karupmøllerite-Ca and gjerdingenite-Ca. Two stages of mineral formation—pegmatite proper and hydrothermal—have been recognized in the host pegmatite. The hydrothermal stage included K-Ba-Na, Na-K-Ca, and Na-Sr substages. Burovaite-Ca is related to the intermediate Na-K-Ca substage. At the first substage, labuntsovite-Mn and lemmleynite-Ba were formed, and tsepinite-Na, paratsepinite-Nd, and tsepinite-Sr were formed at the final substage. Thus, the sequence of crystallization of labuntsovite

  2. Síntese de zeólitas a partir de cinza volante de caldeiras: caracterização física, química e mineralógica Synthesis of zeolites from boiler fly ash: physical, chemical and mineralogical characterization

    Directory of Open Access Journals (Sweden)

    C. A. F. Rocha Junior

    2012-03-01

    chemical, physical and mineralogical characterization methods were carried out: X-ray diffractometry, X-ray fluorescence, scanning electron microscopy, granulometric analysis, differential thermal and thermogravimetric analysis (DTA-TG. The analyses were carried out at the following conditions: 60, 100, 150 and 190 °C, Na2O/Al2O3 molar ratio of 5 and Si/Al molar ratio ranging from 2.12 to 15, and reaction time of 24 h. The results of the fly characterization demonstrate its enormous potential as raw material for the zeolite synthesis. SiO2 and Al2O3 represent more than 50% of its composition, mineralogical phases defined, low humidity content, low particle size (d90 < 10 µm, among others. Mineralogical analyses of the synthesized products showed the formation of some zeolite types, as follow: analcime, phillipsite, sodalite, zeolite P and tobermorite. The results show that the mixture fly ash-microsilica in these reaction conditions point to a promising material for zeolite synthesis.

  3. Hydrothermal Synthesis of Zeolite from Coal Class F Fly Ash. Influence of Temperature

    Directory of Open Access Journals (Sweden)

    Goñi, S.

    2010-06-01

    Full Text Available The influence of temperature of alkaline hydrothermal treatment on the conversion in zeolite of Spanish coal low calcium-fly ash (ASTM class F is presented in this work. Zeolite Na-P1 gismondine type (Na6Al6Si10O32.12H2O was formed at the temperature of 100ºC, which transformed in zeolite; analcime-C type (Na(Si2AlO6H2O and sodalite (1.08 Na2O.Al2O3.1.68SiO2.1.8H2O at 200ºC together with traces of tobermorite-11Å (Ca5(OH2Si6O16.4H2O. At this temperature the 100% of the fly ash reaction was allowed. An equivalent study was carried out in water as reference. The zeolite conversion of the fly ash was characterized by X ray diffraction (XRD, FT infrared (FTIR spectroscopy, surface area (BET-N2 and thermal analyses.

    En este trabajo se presenta el papel que juega la temperatura durante el tratamiento hidrotermal en medio alcalino para convertir una ceniza volante de bajo contenido en cal (clase F, según la norma ASTM en zeolita. Durante este tratamiento a la temperatura de 100ºC se forma Zeolita Na-P1 tipo gismondina (Na6Al6Si10O32.12H2O; al elevar la temperatura a 200ºC, dicha zeolita se transforma en zeolita Analcima C (Na(Si2AlO6H2O y en fase sodalita (1.08 Na2O.Al2O3.1.68SiO2.1.8H2O junto con trazas de tobermorita-11Å (Ca5(OH2Si6O16.4H2O. A esta temperatura y en estas condiciones se ha conseguido un 100% de reacción. Un estudio equivalente se ha llevado a cabo empleando agua como medio de referencia. La conversión de ceniza volante en zeolita se ha caracterizado mediante técnicas, como difracción de Rayos X (DRX, espectroscopia

  4. Composition and diagenetic processes of sandstone and tuff deposits of the Cenomanian Cardiel Formation, Cardiel Lake area, province of Santa Cruz Composición y procesos diagenéticos de los depósitos de arenisca y toba de la Formación Cardiel (Cenomaniano, área Lago Cardiel, provincia de Santa Cruz

    Directory of Open Access Journals (Sweden)

    R.R. Andreis

    2007-06-01

    Full Text Available The Cardiel Formation (Cenomanian, around 200 m in thickness in the studied area, includes different types of volcaniclastic deposits, mainly represented by fine tuffs and massive bentonites, and subordinated epiclastics such as lithic sandstones of yellowish-brown, dusky yellow, or light olive hues, siltstones and claystones. Reddened paleosols with some small axial roots and weak prismatic structures appear on top of siltstones, tuffs and bentonites. Tufites and tuffs contain the same neovolcanic components, abundant glass shards and minor pumices. Different types of glass shards can be differentiated whitin this unit, whereas pumice fragments are represented by different vesicular varieties. Vitreous tuffaceous clasts are abundant in the tufites. Almost all samples contain not only diagenetically-derived, but also pedogenetically-infiltrated montmorillonite, as well as zeolites. Predominant Ca-Na-K clinoptilolite (Si/Al>4 and minor analcime (Si/Al near 3 were identified. Smectite and clinoptilolite may either replace glass-shards or pumices, or fill pore spaces, whereas smectite also appears as thin cutans. The sequence of diagenetic processes includes the conversion (hydrolysis of glass to smectite, and later to zeolites. Furthermore, zeolites preceded calcite growth (sometimes replacing glass-shards or pumices, which in turn, formed prior to pervading ferric oxides-hydroxides. The vertical distribution of zeolites can be explained taking into account the presence of percolating waters in an open hydrologic system. The zeolite content throughout the whole profile links the mineralogical association observed within the sediments of the Cardiel Formation to the clinoptilolite zone. Paleoenvironmental reconstructions for the Cardiel Formation point out to tidal currents taking place in wide lagoons; tuffaceous and bentonitic deposits covered those ancient lagoons forming wide, flat plains on which paleosols developed. Paleocurrents measured on

  5. Corrosion testing of a plutonium-loaded lanthanide borosilicate glass made with Frit B

    International Nuclear Information System (INIS)

    releases of Gd, Hf, and Pu from the glass were also measured. The release of Pu was significantly less than Si at all temperatures and pH values (on a normalized basis). More Gd than Pu or Hf was released from the glass in acidic solutions, but more Pu than Gd or Hf was released in alkaline solutions. Almost all of the released Gd remained in solution in tests conducted in Teflon vessels, whereas about half of the released Pu and Hf became fixed to the Teflon. In tests conducted in Type 304L stainless steel vessels, most of the released Gd, Hf, and Pu became fixed to the steel. The aqueous concentrations of Gd, Hf, and Pu decreased from about 2 x 10-5, 2 x 10-8, and 1 x 10-7 M in tests solutions near pH 3.7 to about 1 x 10-9, 8 x 10-10, and 1 x 10-8 M in test solutions near pH 10.8, respectively, in the 90 C tests in Teflon vessels (the solutions were not filtered prior to analysis). Vapor hydration tests (VHTs) were conducted at 120 and 200 C with Pu LaBS-B glass and SRL 418 glass, which was made to represent the HLW glass that will be used to macro-encapsulate LaBS glass within the waste form. Some VHTs were conducted with specimens of Pu LaBS-B and SRL 418 glasses that were in contact to study the effect of the solution generated as HLW glass dissolves on the corrosion behavior of Pu LaBS-B glass. Other VHTs were conducted in which the glasses were not in contact. The Pu LaBS-B glass is more durable than the HLW glass under these accelerating test conditions, even when the glasses are in contact. The presence of the SRL 418 glass did not promote the dissolution of the Pu LaBS-B glass significantly. However, Gd, Hf, and Pu were detected in alteration phases formed on the Pu LaBS-B glass surface and in (or on) phases formed by SRL 418 glass degradation, such as analcime. This indicates that Gd, Hf, and Pu were transported from the LaBS glass, through the water film formed on the specimens, and to the SRL 418 glass during the test. The disposition of the PuO2 inclusion

  6. A study on zeolite precipitation at alkaline conditions: effect of solution composition on mineralogy and crystallization rate

    International Nuclear Information System (INIS)

    .8. In addition, crystalline products have Si/Al ratios that are almost the same a s their amorphous precursors. These results indicate that the composition of the crystalline material is directly inherited from its amorphous precursor. Thus, the lower Si/Al ratio of the amorphous products from the Al-rich systems favored the precipitation of Zeolite A, which has a Si/Al ratio of 1, whereas the higher Si/Al ratio of the amorphous products from the Si-rich systems favored the precipitation of the relatively more siliceous zeolites faujasite and phillipsite. The data, therefore, suggest that the composition of the starting fluid, particularly its Si/Al ratio, control the Si/Al ratio of the precursor phase, which determines the mineralogy. The observed phases are markedly different from zeolites commonly observed in bentonite alteration experiments. In particular, the absence of analcime, which typically forms in Na dominated systems, is noteworthy. This may be attributed to the relatively high concentrations of Si and Al used in these experiments, in contrast to the low concentrations commonly observed in bentonite alteration studies. This observation further highlights the role of solution composition in determining zeolite mineralogy. The results show that at fixed pH, the composition of the solution, particularly its Si/Al ratio controls the rate of crystallization and the mineralogy of the zeolites that precipitate. For the Al-rich solutions with Si/Al 1, siliceous zeolites faujasite and phillipsite crystallized at a slower rate. The dependence of rate on the composition is explained by the formation of aluminosilicate polymers that build the zeolite framework. The dependence of mineralogy on composition is due to the solution controlling the composition of the amorphous precursor phase, from which the zeolite inherits its composition. (authors)

  7. Procesos de formación de paragénesis ceolíticas en el metamorfismo de muy bajo grado de las volcanitas paleógenas al sur de Confluencia, Neuquén, República Argentina Formation of zeolitic assemblages during very low grade metamorphism of Paleogene volcanic rocks, south of Confluencia, Neuquén, Argentina

    Directory of Open Access Journals (Sweden)

    María E. Vattuone

    2001-12-01

    edad miocena inferior; posteriormente, un fracturamiento tensional (Mioceno Superior? favoreció la acción de nuevos fluidosA metamorphic assemblage of very low grade metamorphism in Paleogene volcanic rocks from the Andesitic Formation, Confluencia, Neuquén Province, is studied. The protolith is basaltic and andesitic. The secondary minerals are calcic, calcosodic and sodic zeolites. Wairakite is the first zeolite to crystallize, together with other minerals like albite, adularia, pumpellyite, titanite, pectolite, pyrite, native copper, hematite, smectite and quartz in the matrix and in phenocrysts. They were followed by laumontite, yugawaralite, and sodic wairakite in the matrix and in amygdales. Later on, only in amygdales, sodic wairakite was replaced by scolecite and mesolite, whereas laumontite and yugawaralite were replaced by heulandite and calcic clinoptilolite. Then barrerite, tetranatrolite and paranatrolite replaced albite and adularia was replaced by illite. These assemblages are in accordance with a pervasive geothermal field type, very low grade metamorphism in the zeolite facies. The equilibrium assemblage wairakite-yugawaralite-albite indicates P-T conditions of <0,5kb and <220°C. At temperatures lower than 200°C in the zeolite facies heulandite group minerals, scolecite and mesolite formed replacing the first association. In a second event, at temperature lower than 150°C, barrerite, paranatrolite and tetranatrolite precipitated in joints together with stilbite and stellerite. Other process, formed analcime by replacement of barrerite. Then, an increase in X CO2 favoured the precipitation of calcite in joints. The thermal waters were neutral to slightly alkaline, the ƒO2 conditions were in the hematite - pyrite stability field, the P H2O / Ptotal ratio was high and then, decrases in the joints, at the same time that X C2O was increasing; it was low during the main process. The geothermal system was heated by Early Miocene magmatic intrusions

  8. Paravinogradovite, (Na,□)2 [(Ti4+, Fe3+)4 {Si2 O6}2 {Si3 Al O10} (OH)4] H2O, a new mineral species for the Khibina alkaline massif, Kola Peninsula, Russia: description and crystal structure

    International Nuclear Information System (INIS)

    Paravinogradovite is a new mineral species from Mount Kukisvumchorr, Khibina alkaline massif, Kola Peninsula, Russia. Paravinogradovite forms prismatic crystals elongate along [100] and up to 0.5-1.0cm long; crystals in some cases occur in fan-shaped aggregates sporadically scattered throughout a matrix of feldspar, nepheline and natrolite in a strongly mineralized nepheline-feldspar pegmatite. Associated minerals are nepheline, K-feldspar, albite, analcime, natrolite, aegirine, biotite, chlorite, zircon, ilmenite, pyrochlore, ancylite-(Ce), nordstrandite, carbonate-fluorapatite, fluorite, galena and cerussite. Crystals of paravinogradovite are colorless to white, with a white streak and a luster that varies from vitreous to pearly. The mineral is translucent to transparent, and shows weak yellow-green fluorescence under 240-400 nm ultraviolet radiation. Paravinogradovite has a perfect cleavage on {001} and an indistinct cleavage on {010}. It is brittle, has a splintery fracture and a Mohs hardness of 5. Its observed and calculated densities are 2.77(2) and 2.76 g/cm3, respectively. It is biaxial negative with α 1.707(2), β 1.741(2), γ 1.755(2), 2V(obs.) = 64(1)o, 2V(calc.) = 64o, nonpleochroic with dispersion r> v, with Z ∼ b, X Λα 30o. Paravinogradovite is triclinic, space group P1, a 5.2533(1), b 8.7411(3), c 12.9480(5) Angstroem, α 70.466(1), β 78.472(1), γ 89.932(1)o, V547.65(5) )Angstroem, Z = 1. The strongest seven lines in the X-ray powder-diffraction pattern [d in Angstroem(I)((hkl)] are: 3.182(100)(0 13,014), 5.88(65)(011,012), 11.9(58)(001), 4.35 (38)(021,102), 5.98(35)(002), 3.085(29)(123) and 2.735(21)(122). Chemical analysis by electron microprobe gave SiO2 43.54, A12O3 6.12, Fe2O3 4.11, Nb2O5 0.50, TiO2 29.59, BeO 0.76, MgO 0.13, Na2O 7.77, K2O 0.87, H2O 6.23, sum 99.62 wt.%, where the amount of Be and the amount of H2O were determined by crystal-structure analysis, and the valence state of Fe was determined by Moessbauer spectroscopy. The

  9. Uranium geology and chemistry, programme and book of abstracts

    International Nuclear Information System (INIS)

    column in the presence of humic acids; 35 - U speciation and stability factors in the Cominak mining wastes (Niger); 36 - IMOURAREN - leaching tests and analcimes specificity; 37 - Modeling of U ore acid leaching tests, application to in-situ recovery; 38 - Role of detrital pyrites in U concentration in the meso-Archean Pongola basin (2.9 Ga, South Africa); 39 - The role of black chert pebbles in uranium mineralisation in conglomerates of the basal Mozaan Group (Pongola basin, South Africa); 40 - U hydrothermal alteration and leaching in the Questembert granite (Massif Armoricain, France)

  10. Modeling of the chemical interactions between concrete and Febex bentonite subjected to hydration and a thermal gradient

    International Nuclear Information System (INIS)

    Document available in extended abstract form only. Concrete can be used in a radioactive waste repository to support either the bentonite barriers in disposal tunnels or the access galleries. Concrete degradation generates an alkaline plume that can affect the swelling and transport properties of the bentonite barriers and the clayey host rock in contact with concrete. Various studies have been performed in order to study the influence of alkaline solutions on the FEBEX bentonite. For instance, Cuevas et al. carried out a set of batch and column experiments on the system alkaline-water/mortar/bentonite in the temperature range 25-120 deg. C. The main phases identified during these experiments were tobermorite or C-S-H gels, Mg-clays and zeolites (analcime, phillipsite). Precipitation of a smectitic tri-octahedral phase was confirmed, as well. In the framework of the NF-Pro Project, a series of complementary tests were designed to study the interactions between concrete (CEM-I cement) and the FEBEX bentonite under more relevant repository conditions. The tests were carried out in hermetic cylindrical cells in which a concrete slab was placed on the top of a compacted bentonite block. Hydration was performed with a synthetic solution by applying a hydraulic pressure of 12 bars at the concrete slab. The solution mimicked a Na-Cl-SO4 pore water found in Spanish argillaceous formations. A constant thermal gradient was also established in the cells, ranging from 25 deg. C on the top of the concrete slab to 100 deg. C at the bottom of the bentonite block. Three of the cells were dismantled after 6, 12 and 18 months of operation. The chemical and mineralogical evolutions of the concrete slab and the bentonite block were modeled with the reactive transport code HYTEC, taking into account hydration and a temperature gradient. The thermal and suction properties of the materials were correctly considered in the calculations but not the important process of vapor transport (i