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)

Smyth, J.R.; Caporuscio, F.A.

1981-06-01

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 85 0 C. This may restrict allowable gross thermal loadings in waste repositories in volcanic rocks

Analcite formation in the Agades Region (Niger)

International Nuclear Information System (INIS)

1966-06-01

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) [fr

Novel thermosyphon driven hydrothermal flow-through cell for in situ and time resolved neutron diffraction studies

International Nuclear Information System (INIS)

Xia, Fang; Qian, Gujie; Etschmann, Barbara; University of Adelaide, South Australia, Australia; University of Adelaide, South Australia, Australia; Studer, Andrew; Olsen, Scott

2009-01-01

Full text: A flow-through cell for hydrothermal phase transformation studies by in situ and time-resolved neutron diffraction has been designed and constructed. The cell has a large internal volume of 320 m L and can work at up to 300 degree Centigrade under autogeneous vapour pressures (-85 bar). The fluid flow is driven by thermosyphon which is realized by the proper design of temperature difference around the closed loop[1,2). The main body of the cell is made of stainless steel (316 type), but the sample compartment is constructed from non-scattering Ti/Zr alloy. We have successfully commissioned the cell on Australia's new high intensity powder diffractometer WOMBAT in ANSTO, using a simple transformation reaction from leucite (KAISi 2 O 6 ) to analcime (NaAISi 2 O 6H2O ) and then back from analcime to leucite. The demonstration proved that the cell is an excellent tool for probing hydrothermal phase transformations. By collecting diffraction data every 5 min, it was clearly seen that leucite was progressively transformed to analcime in a NaCI solution, and the produced analcime was progressively transformed back to leucite in a K 2 CO 3 solution.

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)

Billon, Sophie

2014-01-01

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)

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

International Nuclear Information System (INIS)

Barnes, H.L.; Wilkin, R.T.

1995-08-01

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

Electron irradiation of zeolites

International Nuclear Information System (INIS)

Wang, S.X.; Wang, L.M.; Ewing, R.C.

1999-01-01

Three different zeolites (analcime, natrolite, and zeolite-Y) were irradiated with 200 keV and 400 keV electrons. All zeolites amorphized under a relatively low electron fluence. The transformation from the crystalline-to-amorphous state was continuous and homogeneous. The electron fluences for amorphization of the three zeolites at room temperature were: 7.0 x 10 19 e - /cm 2 (analcime), 1.8 x 10 20 e - /cm 2 (natrolite), and 3.4 x 10 20 e - /cm 2 (zeolite-Y). The different susceptibilities to amorphization are attributed to the different channel sizes in the structures which are the pathways for the release of water molecules and Na + . Natrolite formed bubbles under electron irradiation, even before complete amorphization. Analcime formed bubbles after amorphization. Zeolite-Y did not form bubbles under irradiation. The differences in bubble formation are attributed to the different channel sizes of the three zeolites. The amorphization dose was also measured at different temperatures. An inverse temperature dependence of amorphization dose was observed for all three zeolites: electron dose for amorphization decreased with increasing temperature. This unique temperature effect is attributed to the fact that zeolites are thermally unstable. A semi-empirical model was derived to describe the temperature effect of amorphization in these zeolites

Effects of alteration product precipitation on glass dissolution

Energy Technology Data Exchange (ETDEWEB)

Strachan, Denis M.; Neeway, James J.

2014-06-01

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 rate constant at a constant analcime precipitation rate constant. From the simulations we conclude, firstly, that the rate of glass dissolution is dependent on the kinetics of

Preparation of leucite based materials

Czech Academy of Sciences Publication Activity Database

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

90-91, - (2003), s. 377-382 ISSN 1012-0394 Institutional research plan: CEZ:AV0Z4032918; CEZ:MSM 223100002 Keywords : leucite * analcime * hydrothermal synthesis Subject RIV: CA - Inorganic Chemistry Impact factor: 0.687, year: 2003

Phase formation during corrosion experiments with two simulated borosilicate nuclear waste glasses

International Nuclear Information System (INIS)

Haaker, R.F.

1985-10-01

Corrosion products resulting from the reaction of simulated high-level radioactive waste glasses with various solutions have been identified. At 200degC, in saturated NaCl, a degree of reaction of 10 g C31-3 glass or 2.6 g SON 68 glass per liter of solution was obtained. Analcime, vermiculite (a phyllosilicate) and a 2:1 zinc silicate are the major silica containing alteration products for the C31-3 glass. Analcime was the only silicate alteration product which could be identified for SON 68 glass. C31-3 glass appeared to be less reactive with a quinary brine containing Mg ++ than with NaCl. With the quinary brine, montmorillonite (a phyllosilicate) was the predominant silica containing alteration product. Hydrotalcite (a Mg-Al hydroxysulfate) and montmorillonite were the major Al-containing phases. A phyllosilicate, probably montmorillonite, was observed to form during the reaction of SON 68 glass with quinary brine. With either glass, modified NaCl brines which contained small amounts of MgCl 2 seem to have the effect of decreasing the amount of analcime and increasing the amount of phyllosilicate which is formed. In the case of C31-3 glass, there is approximately enough Mg, Al and Zn to precipitate most of the leached Si; measured Si concentrations remain well below that expected for amorphous silica. SON 68 glass has less Zn, Al and Mg than C31-3 glass and much higher Si concentrations of the leachates. (orig./RB)

Browse Title Index

African Journals Online (AJOL)

Items 51 - 100 of 1025 ... ... at trace levels using Celestine blue-KIO4-1,10-phenantroline redox ... of some preconcentration methods for certain metal ions in human .... natural analcime zeolite loaded 2,3,5,6-tetra(2-pyridyl)pyrazine, Abstract PDF.

Aqueous alteration of Japanese simulated waste glass P0798: Effects of alteration-phase formation on alteration rate and cesium retention

International Nuclear Information System (INIS)

Inagaki, Y.; Shinkai, A.; Idemistu, K.; Arima, T.; Yoshikawa, H.; Yui, M.

2006-01-01

Aqueous alteration tests were performed with a Japanese simulated waste glass P0798 in alkaline solutions as a function of pH or species/concentration of alkaline metals in the solution in order to evaluate the alteration conditions determining whether smectite (2:1 clay mineral) or analcime (zeolite) forms as the major alteration-phase. XRD analysis of the alteration-phases showed that smectite forms at any pH between 9.5 and 12, and analcime forms at pH above 11, though the formation also depends on species and concentrations of alkaline metals in the solution. These results cannot agree with the thermodynamically predicted phase stability, e.g., smectite is more stable than the thermodynamic prediction shows. On the basis of the results of alteration conditions, the alteration tests were performed under smectite forming conditions, where only smectite forms or no crystalline phases form, in order to evaluate the alteration rate and the mechanism of cesium release/retention. The results showed that the glass alteration proceeds slowly in proportion to square root of time under smectite forming conditions, which indicates that the alteration rate can be controlled by a diffusion process. It was suggested that the alteration rate under smectite forming conditions is independent of the pH, alkaline metal species/concentration in the solution and whether smectite actually forms or not. The results also indicated that most of cesium dissolved from the glass can be retained in the alteration-phases by reversible sorption onto smectite or irreversible incorporation into analcime, pollucite or solid solutions of them

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)

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)

Carroll, P.I.; Caporuscio, F.A.; Bish, D.L.

1981-11-01

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

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.

Ion Exchange Properties of Georgian Natural Zeolites

Directory of Open Access Journals (Sweden)

Vladimer Tsitsishvili

2017-06-01

Full Text Available Ion-exchange properties of natural zeolites of Georgia with a relatively low Si/Al ratio have been studied: analcimes are characterized by selectivity series: Na+>K+>Ag+>NH4+>Ca+2>Sr+2>Li+; for phillipsites selectivity sequences are different for calcium- and potassium forms; selectivity sequence for scolecite is: Sr+2>Ba+2>Rb+>Ca+2>Cs+>K+>NH4+>Na+>Mg+2>Li+>Cd+2>Cu+2> Mn+2> Zn+2>Co+2>Ni+2.

Zeolites of the Valle Central of Costa Rica and its outskirts

International Nuclear Information System (INIS)

Zeledon, Luis Alonso

2004-01-01

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) [es

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

International Nuclear Information System (INIS)

Waters, A.C.; Carroll, P.R.

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

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.

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.

Radiation effects on materials in the near-field of nuclear waste repository. 1998 annual progress report

International Nuclear Information System (INIS)

Ewing, R.C.; Wang, L.M.

1998-01-01

'Site restoration activities at DOE facilities and the permanent disposal of nuclear waste generated at DOE facilities involve working with and within various types and levels of radiation fields. Once the nuclear waste is incorporated into a final form, radioactive decay will decrease the radiation field over geologic time scales, but the alpha-decay dose for these solids will still reach values as high as 10 18 alpha-decay events/gm in periods as short as 1,000 years. This dose is well within the range for which important chemical (e.g., increased leach rate) and physical (e.g., volume expansion) changes may occur in crystalline ceramics. Release and sorption of long-lived actinides (e.g., 237 Np) can provide a radiation exposure to backfill materials, and changes in important properties (e.g., cation exchange capacity) may occur. The objective of this research program is to evaluate the long term radiation effects in the materials in the near-field of a nuclear waste repository with accelerated experiments in the laboratory using energetic particles (electrons, ions and neutrons). Experiments on the microstructural evolution during irradiation of two important groups of materials, sheet silicates (e.g., clays) and zeolites (analcime), have been conducted; and studies of radiation-induced changes in chemical properties (e.g. cation exchange capacity) are underway. As of the mid-2nd year of the 3-year project, experiments on the microstructural evolution during irradiation of two important group of materials, sheet silicates (mica) and zeolites (analcime), have been conducted; and studies of radiation-induced changes in chemical properties (e.g., cation exchange capacity) are underway.'

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)

1993-01-01

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

Mineralogy, geochemistry and low grade metamorphism of green tuffs of Karaj formation in Hesarbon area (south west Firoozkooh

Directory of Open Access Journals (Sweden)

Shiva Bahrami

2017-03-01

Full Text Available Green tuffs of middle Eocene age in Hesarbon area, south west of Firoozkuh (East of Central Alborz consist of a thick sequence of lithic-, crystal-,vitric-and calcareous-tuffs. Microscopic and x-ray diffraction studies show plagioclase (albite and oligoclase, alkali feldspar (sanidine, quartz, cristobalite, biotite and hornblende are the major minerals in the rocks studied. Secondary minerals such as analcime, chlorite, prehnite and clay minerals are mainly present in the groundmass of the rocks. Extensive tectonic activities have created a variety of structural features including numerous folds and faults and therefore, have caused the green tuffs to be crushed and converted to breccia tuffs in many parts. Veins and cavities are filled by considerable amounts of zeolitic minerals including heulandite group, clinoptilolite and natrolite along with calcite and secondary quartz. Based on geochemical data, they lie on the dacite and rhyodacite field showing a calc-alkaline nature in the corresponding diagrams. According to the chondrite and primitive mantle normalized diagrams of trace elements, negative anomalies of Eu, Nb, Ti, P and depletion of HFSE together with their position in the petrogenesis discrimination diagrams, it is most likely that these rocks are formed in the active continental margin of a subduction zone. The existence of analcime and prehnite in the groundmass demonstrate that these rocks have undergone some degrees of low-grade metamorphism due to the overburden of the layers in the temperature range 200-300 °C. The present study shows that zeolite minerals filling the fractures and cavities of tuffs are precipitated by hydrothermal fluids with a neutral pH to acidic

Zeolite facies and regional rank of bituminous coals

Energy Technology Data Exchange (ETDEWEB)

Kisch, H J

1966-01-01

The author has correlated diagnostic analcime-, heulandite-, and laumontite-bearing mineral assemblages from four areas in the Upper Carboniferous and the Permian of New South Wales with the rank of the associated coals, represented by the carbon content of vitrinite. The results show that lowest-grade regional metamorphism of the zeolite facies reflects at least in part the same physical conditions of metamorphism as the increase in degree of coalification (rank) in the bituminous coal range. Degree of coalification is probably independent of partial pressures of H/sub 2/O and CO/sub 2/: it is controlled mainly by maximum depth of burial, its duration, and the geothermal gradient.

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)

Nibou, D.

1990-06-01

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

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.

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.

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.

A short review of the formation, stability, and cementing properties of natural zeolites

International Nuclear Information System (INIS)

Jacobsson, A.

1977-10-01

The buffer mass for embedding nuclear waste canisters way down in tunnels or bore holes must fulfil a number of requirements. A 10-15 percent (by weight) sodium bentonite and 85-90 percent quartz mass has been suggested. In most respects this buffer mass has excellent properties but its ion exchange capacity is moderate or low. For this reason zeolites have been suggested as an active component in the mass. The question has been, however, whether zeolites are chemically stable together with other minerals such as montmorillonite which still has to be used to give the buffer mass suitable plastic and permeable properties. It is the main object of this report to illustrate any behaviour of zeolites relevant to the problem of finding a suitable buffer mass. Analcime or analcite, phillipsite, chabazite and clinoptilolite have been suggested as possible components in our buffer mass. (author)

Geochemical and petrographic investigation of Himmetoglu oil shale field, Goynuk, Turkey

Energy Technology Data Exchange (ETDEWEB)

Sener, M.; Gundogdu, M.N. [General Directorate of Mineral Research and Exploration, Ankara (Turkey)

1996-09-01

The Himmetoglu field is a good example of oil shale fields in Turkey. Mineral and maceral types show that the huminite and liptinite groups tend to be associated with smectite, clinoptilolite and calcite in Himmetoglu oil shale, while the liptinite group is accompanied by analcime and dolomite in bituminous laminated marl. The pH value increases from bottom (pH {lt} 9) to top (pH {gt} 9) in the Himmetoglu formation and volcanogenic materials have played a very important role in deposition of organic matter. The negative correlation between trace elements and organic carbon suggests absence of enrichment of trace elements in oil shales. The results of g.c.-m.s. and carbon isotope analysis show that there is a decrease in the amount of terrestrial organic matter and a relative decrease in maturity of the organic matter in the vertical succession from Himmetoglu oil shape up to the bituminous laminated marl. 8 refs., 6 figs., 5 tabs.

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

International Nuclear Information System (INIS)

Wang Yifei; Lin Feng

2009-01-01

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 Ca 2+ > K + > Mg 2+ .

Zeolites of the Valle Central of Costa Rica and its outskirts; Zeolitas del Valle Central de Costa Rica y sus alrededores

Energy Technology Data Exchange (ETDEWEB)

Zeledon, Luis Alonso [Moravia, San Jose, (Costa Rica)

2004-12-15

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) [Spanish] Se describen 19 especies diferentes de zeolitas procedentes de 25 afloramientos en los alrededores del Valle Central de Costa Rica y en la region de Siquirres. Todas las zeolitas descritas son de origen secundario y se presentan en vetillas y vesiculas de los basaltos y rocas piroclasticas de las formaciones La Cruz y Grifo Alto del Grupo Aguacate y en las rocas igneas alcalinas de Guayacan. Las especies mas frecuentes son estilbita, chabasita, laumontita, mesolita/modernita, thomsonita y analcima. La natrolita solo se encontro en los alrededores de Siquirres. (Autor)

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

International Nuclear Information System (INIS)

Bish, D.L.; Chipera, S.J.

1986-09-01

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

Alteration behavior of bentonite barrier of radioactive waste disposal by alkaline solutions. Part 1. Permeability change of compacted bentonite immersed in alkaline solutions

International Nuclear Information System (INIS)

Yokoyama, Shingo; Nakamura, Kunihiko

2010-01-01

Permeability tests using the compacted bentonites and alkaline solutions were carried out to estimate of alteration behavior and the change of permeability during the alteration reaction. The permeability tests of the compacted bentonites were carried out at 23degC for one week after they were immersed in alkaline solution at 60degC for four weeks (immersing test). After permeability tests, the compacted bentonites were repeatedly tested as the same procedure (i.e. repetition of permeability test and immersing test) at 11 cycles. The compacted bentonites with initial dry density of 1.6 Mg/m 3 were reacted with the different type of the alkaline solutions (deionized water, NaOH (pH=12 and 14), KOH (pH=12 and 14) and Ca(OH) 2 (pH=12)) in each experiments. In the case of deionized water and alkaline solutions of pH12, the mineral compositions of altered bentonite were similar to original bentonite while the exchangeable cations of altered bentonites were changed. No changes of the mineralogical features of montmorillonite in altered bentonites (i.e. illitization, baideritization and increasing of layer charge) were observed in the case of deionized water, pH12-NaOH and pH12-Ca(OH) 2 . The montmorillonite was changed to the illite/smectite interstratified mineral containing about 40% illite like component during the reaction with pH12-KOH. In the case of alkaline solutions with pH14, the component minerals of bentonite (e.g. montmorillonite, quartz and clinoptilolite) were dissolved, consequently secondly minerals (e.g. analcime and phillipsite) were crystallized during experiments. Furthermore, the mineralogical features of montmorillonite were changed as illitization (pH14-KOH), beidellitization (pH14-NaOH and pH14-KOH) and increasing of layer charge (pH14-NaOH and pH14-KOH). No increasing of permeability were observed during the experiment using pH12-NaOH and pH12-Ca(OH) 2 as well as the case of deionized water. In the case of pH12-KOH, the permeability continually

Ab Initio periodic Hartree-Fock study of group IA cations in ANA-type zeolites

International Nuclear Information System (INIS)

Anchell, J.L.; White, J.C.; Thompson, M.R.; Hess, A.C.

1994-01-01

This study investigates the electronic structure of Group IA cations intercalated into zeolites with the analcime (ANA) framework using ab initio periodic Hartree-Fock theory. The purpose of the study is to gain a better understanding of the role played by electron-donating species in zeolites in general, with specific applications to materials that have been suggested as storage matrices for radioactive materials. The effect of the intercalated species (Na, K, Rb, and Cs) on the electronic structure of the zeolite is presented on the basis of an analysis of the total and projected density of states, Mulliken charges, and charge density differences. The results of those analyses indicate that, relative to a charge neutral atomic state, the Group IA species donate an electron to the zeolite lattice and interact most strongly with the s and p atomic states of oxygen as the species are moved through the lattice. In addition, estimates of the self-diffusion constants of Na, K, Rb, and Cs based upon a one-dimensional diffusion model parameterized from the ab initio total energy data will be presented. 24 refs., 8 figs., 4 tabs

Suitability of alumina cements for the cementation of boreholes under corrosive conditions, especially at the press fitting of CO{sub 2}; Eignung von Tonerdezementen fuer die Bohrlochzementierung unter korrosiven Bedingungen, insbesondere bei CO{sub 2}-Einpressung. Literaturstudie

Energy Technology Data Exchange (ETDEWEB)

Plank, J.; Sieber, R. (comps.) [Technische Univ. Muenchen (Germany). Lehrstuhl fuer Bauchemie

2011-07-15

Calcium aluminate cements, also called aluminate cements, are special cements based on calcium aluminates. In construction (especially in dry-mix mortars), they are valued for their remarkably higher acid and corrosion resistance compared to Portland cement. Their high temperature resistance especially qualifies them for refractory cements which are used e.g. as liners in cement rotary kilns. The worldwide production of calcium aluminate cements adds up to about 3 million tons. In oil well cementing, calcium aluminate cements have first been used at the beginning of the 90ies, in fact initially for geothermal wells. Applications in permafrost soils as well as fire-flooding wells came later. The reason for the use in geothermal wells. Applications in permafrost soils as well as fire-flooding wells came later. The reason for the use in geothermal wells were severe problems with API Portland cements affected by hot, carbonic acid rich formation brines. With support from the companies Unocal and Halliburton, the Brookhaven National Laboratory (USA) developed a special cement based on 60 parts by weight of calcium aluminate cement and 40 parts ASTM class F fly ash. This binder is notably CO{sub 2} resistant when mixed with a 25 wt.% Na-polyphosphate solution. Laboratory tests and field applications conclude that this cement is resistant to CO{sub 2} corrosion at temperatures up to 300 C for over 20 years. In 1997, for the first time numerous geothermal wells have been cemented using this cement. They are intact to this day. When this cement hardens at room temperature, amorphous reaction products are formed and the reaction is incomplete. However, at higher temperatures hydroxyapatite, boehmite, Na-P-zeolite, analcime or katoite are formed as crystalline reaction products. The CO{sub 2} resistance of this cement is due to specific chemical reactions. In contact with hot alkaline carbonate solutions, analcime converts to cancrinite, and CO{sub 2} is incorporated into

Chemistry of glass corrosion in high saline brines

International Nuclear Information System (INIS)

Grambow, B.; Mueller, R.

1990-01-01

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 MgCl 2 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 MgCl 2 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

Retention of barium and europium radionuclides from aqueous solutions on ash-based sorbents by application of radiochemical techniques.

Science.gov (United States)

Noli, Fotini; Kapnisti, Maria; Buema, Gabriela; Harja, Maria

2016-10-01

New materials were synthesized for application in sorption of radionuclides from aqueous solutions. The elaboration was performed by conversion of power plant ash using the hydrothermal method under optimum experimental conditions. Sodalite, Na-Y, and analcime were formed from ash precursor during the treatment, exhibiting thermal stability as revealed by the characterization by X-ray diffraction (XRD) and thermogravimetric differential thermal analysis (TG-DTA). The Brunauer-Emmett-Teller (BET) surface area and pore volume were determined and they presented higher values than plant ash. The ability of the new products to retain Ba and Eu radionuclides was studied in aqueous solutions using (133)Ba and (152)Eu as tracers and γ-ray spectroscopy under batch experiments. The experimental data were modeled by the Langmuir and Freundlich equations, whereas sorption kinetics measurements were performed at 293, 308, and 323K and thermodynamic parameters were calculated. The release of the sorbed ions into the environment was also tested by leaching experiments. The results of these tests indicated that the synthesized materials are very efficient in removing the aforementioned metals from aqueous solutions and can be considered as potential low-cost sorbents in nuclear waste management. Copyright © 2016 Elsevier Ltd. All rights reserved.

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

International Nuclear Information System (INIS)

Utada, Minoru

2003-01-01

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)

Two-way Valorization of Blast Furnace Slag: Synthesis of Precipitated Calcium Carbonate and Zeolitic Heavy Metal Adsorbent.

Science.gov (United States)

Georgakopoulos, Evangelos; Santos, Rafael M; Chiang, Yi Wai; Manovic, Vasilije

2017-02-21

The aim of this work is to present a zero-waste process for storing CO2 in a stable and benign mineral form while producing zeolitic minerals with sufficient heavy metal adsorption capacity. To this end, blast furnace slag, a residue from iron-making, is utilized as the starting material. Calcium is selectively extracted from the slag by leaching with acetic acid (2 M CH3COOH) as the extraction agent. The filtered leachate is subsequently physico-chemically purified and then carbonated to form precipitated calcium carbonate (PCC) of high purity (Sodium hydroxide is added to neutralize the regenerated acetate. The morphological properties of the resulting calcitic PCC are tuned for its potential application as a filler in papermaking. In parallel, the residual solids from the extraction stage are subjected to hydrothermal conversion in a caustic solution (2 M NaOH) that leads to the predominant formation of a particular zeolitic mineral phase (detected by XRD), namely analcime (NaAlSi2O6∙H2O). Based on its ability to adsorb Ni 2+ , as reported from batch adsorption experiments and ICP-OES analysis, this product can potentially be used in wastewater treatment or for environmental remediation applications.

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

International Nuclear Information System (INIS)

Medina, Adriana; Gamero, Procoro; Almanza, Jose Manuel; Vargas, Alfredo; Montoya, Ascencion; Vargas, Gregorio; Izquierdo, Maria

2010-01-01

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 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 2 HAsO 4 .7H 2 O originally containing 740 ppb.

The role of pH in the vapor hydration at 175 °C of the French SON68 glass

International Nuclear Information System (INIS)

Ait Chaou, Abdelouahed; Abdelouas, Abdesselam; El Mendili, Yassine; Martin, Christelle

2017-01-01

The French simulated nuclear waste SON68 glass was altered in the presence of water vapor at 175 °C and 98% of relative humidity under several atmospheres (NH_3, H_2S, CO_2 and argon). The objectives were to study the role of pH on hydration kinetics and secondary phases formation. The hydration was followed by infrared spectroscopy and the nature and extent of alteration products were determined by characterizing the reacted glass surface with scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), μ-Raman spectroscopy and X-ray diffraction (XRD). The glass hydration/alteration rate clearly increased with increasing pH, that is controlled by the gas atmosphere, as the following: NH_3 > Ar > CO_2 > H_2S. This can directly be linked to the secondary phases precipitated on the glass surface. Hence, the major alteration products observed at high pH (under NH_3 and Ar) are analcime and Ca-silicates hydrates (CSH) while at low pH (under CO_2 and H_2S) only a hydrated gel layer was identified. - Highlights: • The vapor hydration study of the SON68 glass under geological conditions. • The secondary phases formation in the alteration of SON68 glass. • The pH effect on the alteration kinetics of glass.

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

International Nuclear Information System (INIS)

Lichtner, P.C.; Eikenberg, J.

1995-01-01

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

208-240 M.Y. old jadeite-glaucophane schists in the Kurosegawa tectonic zone near Kochi city, Shikoku

International Nuclear Information System (INIS)

Maruyama, Shigenori; Ueda, Yoshio; Banno, Shohei.

1978-01-01

A new member of the Kurosegawa tectonic zone was found in the serpentinite near Kochi city. They are high P and low T schists derived from basalt and chert. Three metamorphic events can be deciphered in the high-pressure schists, based upon the texture and mineral paragenesis: first, low P metamorphism at intermediate- to high-grade, second, high P and low T metamorphism of the jadeite-glaucophane facies and the third, retrograde crystallization of the second stage high P schists within the stability field of lawsonit + pumpellyite + glaucophane. Further, the formation of analcime replacing jadeite took place. The second and third metamorphism can be distinguished on pyroxene mineralogy that jadeite + quartz was stable in the second, but albite + quartz + aegirinejadeite in the third stage of metamorphism. Not all of the high P and low T schists had suffered low P metamorphism before they were metamorphosed by the high P one. Some basaltic rocks directly changed to high P and low T schists. Two muscovites in the schists give K-Ar ages of 208 - 240 m.y., and a relic igneous biotite, being partly replaced by chlorite, gives 225 m.y. of K-Ar age. These values are different not only from those of the Sanbagawa schists, but also from the other members of the Kurosegawa zone. (author)

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.

Arsenic and uranium transport in sediments near abandoned uranium mines in Harding County, South Dakota

International Nuclear Information System (INIS)

Kipp, Gregory G.; Stone, James J.; Stetler, Larry D.

2009-01-01

Sediment samples were analyzed as part of ongoing environmental investigations of historical U mining impacts within Custer National Forest in Harding County, South Dakota. Correlations between As and U content, grain size and soil mineralogy were determined to identify contaminant fate and transport mechanisms. Soil samples collected near the mining source zone and up to 61 km downgradient of the minesites were analyzed. Samples were homogenized and wet sieved through polymer screens, and metal(loid) concentrations were determined using inductively coupled plasma mass spectrometry (ICP-MS). Powder X-ray diffraction (XRD) analysis identified quartz as the primary mineral for all size fractions, with varying amounts of analcime, indicative of volcanic origin. Selected samples were examined for trace mineral composition using scanning electron microscopy (SEM). The presence of Fe sulfides and Fe (hydr)oxides indicate heterogeneity in redox potentials on a microscopic scale. Elevated metal(loid) concentrations were associated with trace concentrations of Fe sulfide, indicating an influence on metal transport during weathering. Sequential chemical extractions (SCE) performed on source sediment fractions demonstrated that most As and U was adsorbed to Fe- and Mn-oxides and carbonates with lesser amounts bound by ion exchange, organics and Fe sulfides. Large changes in U/Th and As/Th ratios were observed to coincide with geochemical changes in the watershed, suggesting that metal(loid)-Th ratios may be used in environmental investigations to identify geochemically-significant watershed conditions.

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

International Nuclear Information System (INIS)

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

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

Deposition and diagenesis of the Brushy Basin Member and upper part of the Westwater Canyon member of the Morrison Formation, San Juan Basin, New Mexico

International Nuclear Information System (INIS)

Bell, T.E.

1986-01-01

The Brushy Basin Member and the upper part of the Westwater Canyon Member of the Morrison Formation in northwest New Mexico are nonmarine sedimentary rocks of Late Jurassic age. This stratigraphic interval consists of as many as four lithofacies deposited in fluvial and playa-lake environments. Lithofacies A is composed of crossbed feldspathic sandstone and was deposited by braided streams on an alluvial plain. Lithofacies B is composed of crossbedded feldspathic sandstone and tuffaceous mudstone, and was deposited by braided and anastomosing streams at the distal end of the alluvial plain. Lithofacies C is composed of calcareous, tuffaceous mudstone and was deposited on a mudflat between the alluvial plain and a playa lake. Lithofacies D is composed of zeolitic, tuffaceous mudstone and was deposited in a playa lake. The distribution of diagenetic facies in mudstones and tuffs in the Brushy Basin Member and upper part of the Westwater Canyon Member reflects the pH and salinity gradients common to fluvial/playa-lake systems. The abundant vitric ash in the sediments reacted to form montmorillonite in the fluvial facies. Calcite and montmorillonite were the reaction products where the fluvial and outermost playa facies met. Vitric ash reacted to form clinoptilolite and heulandite along the playa margins. In the center of the playa facies, analcime replaced clinoptilolite, an early zeolite. These early diagenetic minerals were replaced by albite, quartz, and mixed-layer illitemontmorillonite where the Brushy Basin Member and upper part of the Westwater Canyon Member have been deeply buried in the San Juan basin

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.  

Zeolitization of intracaldera sediments and rhyolitic rocks in the 1.25 Ma lake of Valles caldera, New Mexico, USA

Science.gov (United States)

Chipera, Steve J.; Goff, Fraser; Goff, Cathy J.; Fittipaldo, Melissa

2008-12-01

Quantitative X-ray diffraction analysis of about 80 rhyolite and associated lacustrine rocks has characterized previously unrecognized zeolitic alteration throughout the Valles caldera resurgent dome. The alteration assemblage consists primarily of smectite-clinoptilolite-mordenite-silica, which replaces groundmass and fills voids, especially in the tuffs and lacustrine rocks. Original rock textures are routinely preserved. Mineralization typically extends to depths of only a few tens of meters and resembles shallow "caldera-type zeolitization" as defined by Utada et al. [Utada, M., Shimizu, M., Ito, T., Inoue, A., 1999. Alteration of caldera-forming rocks related to the Sanzugawa volcanotectonic depression, northeast Honshu, Japan — with special reference to "caldera-type zeolitization." Resource Geol. Spec. Issue No. 20, 129-140]. Geology and 40Ar/ 39Ar dates limit the period of extensive zeolite growth to roughly the first 30 kyr after the current caldera formed (ca. 1.25 to 1.22 Ma). Zeolitic alteration was promoted by saturation of shallow rocks with alkaline lake water (a mixture of meteoric waters and degassed hydrothermal fluids) and by high thermal gradients caused by cooling of the underlying magma body and earliest post-caldera rhyolite eruptions. Zeolitic alteration of this type is not found in the later volcanic and lacustrine rocks of the caldera moat (≤ 0.8 Ma) suggesting that later lake waters were cooler and less alkaline. The shallow zeolitic alteration does not have characteristics resembling classic, alkaline lake zeolite deposits (no analcime, erionite, or chabazite) nor does it contain zeolites common in high-temperature hydrothermal systems (laumontite or wairakite). Although aerially extensive, the early zeolitic alteration does not form laterally continuous beds and are consequently, not of economic significance.

Analytical electron microscopy study of surface layers formed on the French SON68 nuclear waste glass during vapor hydration at 200 C

International Nuclear Information System (INIS)

Gong, W.L.; Wang, L.M.; Ewing, R.C.; Bates, J.K.; Ebert, W.L.

1998-01-01

Extensive solid-state characterization (AEM/SEM/HRTEM) was completed on six SON68 (inactive R7T7) waste glasses which were altered in the presence of saturated water vapor (200 C) for 22, 91, 241, 908, 1000, 1013, and 1021 days. The samples were examined by AEM in cross-section (lattice-fringe imaging, micro-diffraction, and quantitative thin-film EDS analysis). The glass monoliths were invariably covered by a thin altered rind, and the surface layer thickness increased with increasing time of reaction, ranging from 0.5 to 30 μm in thickness. Six distinctive zones, based on phase chemistry and microstructure, were distinguished within the well-developed surface layers. Numerous crystalline phases such as analcime, gyrolite, tobermorite, apatite, and weeksite were identified on the surfaces of the reacted glasses as precipitates. The majority of the surface layer volume was composed of two basic structures that are morphologically and chemically distinct: The A-domain consisted of well-crystallized fibrous smectite aggregates; and the B-domain consisted of poorly-crystallized regions containing smectite, possibly montmorillonite, crystallites and a ZrO 2 -rich amorphous silica matrix. The retention of the rare-earth elements, Mo, and Zr mostly occurred within the B-domain; while transition metal elements, such as Zn, Cr, Ni, Mn, and Fe, were retained in the A-domain. The element partitioning among A-domains and B-domains and recrystallization of the earlier-formed B-domains into the A-domain smectites were the basic processes which have controlled the chemical and structural evolution of the surface layer. The mechanism of surface layer formation during vapor hydration are discussed based on these cross-sectional AEM results. (orig.)

Natural sorptive barriers in Yucca Mountain, Nevada, for long-term isolation of high-level waste

International Nuclear Information System (INIS)

Bish, D.L.; Vaniman, D.T.; Rundberg, R.S.; Wolfsberg, K.; Daniels, W.R.; Broxton, D.E.

1984-01-01

There are several sorptive phases occurring naturally in the silicic tuffs at Yucca Mountain, Nevada, that can aid in the long-term isolation of high-level wastes. These phases include hydrated volcanic glasses, smectites and zeolites. Los Alamos has a continuing programme to investigate the mineralogy and stratigraphy of the tuffs at Yucca Mountain. In addition, extensive data have been obtained on the sorptive behaviour of technetium, strontium, caesium, barium, cerium, europium, uranium, neptunium, plutonium and americium on the minerals in tuffs. Sorption of elements by ion-exchange processes is high in tuffs containing smectite and the zeolites clinoptilolite-heulandite and mordenite. Moreover, sorption correlates with abundances of these minerals. Sorption is not as high for the zeolite analcime and for volcanic glass. Elements that may not sorb by ion exchange, e.g. plutonium, also tend to be sorbed when the zeolite abundance is high, but the correlations are less clearly defined. Because of the correlation between sorptive capacity and mineralogy, an accurate knowledge of mineral distribution and stratigraphy is essential. The distribution of hydrated glasses is stratigraphically controlled, and the glasses occur in narrow unaltered horizons as vitrophyres and as vitric tuff. Although glasses are of minor importance as sorptive phases, they are very reactive and can alter to other minerals if heated in the presence of water. Smectite clays are reversibly expandable and are widespread in tuffs, but their beneficial properties can be modified by prolonged exposure to elevated temperatures. The zeolites clinoptilolite-heulandite and mordenite occur in high concentrations in silicic tuffs, mostly as secondary alterations of non-welded and poorly welded tuffs; their distribution is therefore stratigraphically controlled

Raman and X-ray absorption spectroscopic studies of hydrothermally altered alkali-borosilicate nuclear waste glass

Energy Technology Data Exchange (ETDEWEB)

McKeown, David A., E-mail: davidm@vsl.cua.ed [Vitreous State Laboratory, Catholic University of America, 620 Michigan Ave., N.E., Washington, DC 20064 (United States); Buechele, Andrew C.; Viragh, Carol; Pegg, Ian L. [Vitreous State Laboratory, Catholic University of America, 620 Michigan Ave., N.E., Washington, DC 20064 (United States)

2010-04-01

Raman spectroscopy and X-ray absorption spectroscopy (XAS) are used to characterize structural changes that took place in hydrothermally altered (Na,K)-alumina-borosilicate glasses with different Na/K ratios, formulated as part of a durability study to investigate the behavior of glasses for nuclear waste storage. The hydrothermal experiments, or vapor hydration tests (VHT), were performed on each glass for 3 and 20 days at 200 deg. C to accelerate and approximate long-term alteration processes that may occur in a nuclear waste repository. Results found for both glasses and their VHT altered counterparts show little, if any, structural influence from the different starting Na/K ratios. X-ray diffraction, differential scanning calorimetry, scanning electron microscopy, and Raman spectroscopy indicate that the altered samples are mostly amorphous with small amounts of analcime-like and leucite-like crystals within 200 mum of the sample surface and contain up to 9.7 wt.% water or OH. The Raman data are nearly identical for the amorphous portions of all altered VHT samples investigated, and indicate that two glass structural changes took place during alteration: one, partial depolymerization of the alumina-borosilicate network, and two, introduction of water or OH. Al and Si XAS data indicate tetrahedral AlO{sub 4} and SiO{sub 4} environments in the original glasses as well as in the altered samples. Small energy shifts of the Si K-edge also show that the altered VHT samples have less polymerized networks than the original glass. Na XAS data indicate expanded Na environments in the VHT samples with longer Na-O distances and more nearest-neighbor oxygen atoms, compared with the original glasses, which may be due to hydrous species introduced into the expanding Na-sites.

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

Energy Technology Data Exchange (ETDEWEB)

Wanty, R.B.; Langmuir, D.; Chatham, J.R.

1981-08-01

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.

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)

Wanty, R.B.; Langmuir, D.; Chatham, J.R.

1981-08-01

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

Paleotransport of lanthanides and strontium recorded in calcite compositions from tuffs at Yucca Mountain, Nevada, USA

International Nuclear Information System (INIS)

Vaniman, D.T.; Chipera, S.J.

1996-01-01

Secondary calcite occurs in both saturated and unsaturated hydrologic zones (SZ and UZ, respectively) in the tuffs at Yucca Mountain, Nevada, USA. In the upper UZ, the major constituents of the calcite crystal structure (C, O) have surface origins. At greater depth there is a open-quotes barren zone,close quotes straddling the water table, where calcite is rare and mixing of surface and subsurface sources may occur. Deep in the SZ, distinctive Mn calcites reflect deep sources, including Ca released as analcime or albite formed and carbonates derived from underlying Paleozoic rocks. In the UZ and in the barren zone, above the deep Mn calcites, variations in calcite lanthanide chemistry can be used to distinguish rhyolitic from quartz-latitic sources. Lanthanide ratios and Sr contents of calcites record the chemical evolution of waters flowing through the UZ and upper SZ. Variations in calcite chemistry in the UZ and in the barren zone show that (1) Sr, which is readily exchanged with clays or zeolites, is essentially removed from some flowpaths that are in contact with these minerals and (2) traces of Mn oxides found in the tuffs have a significant effect of groundwater chemistry in the UZ and in the barren zone by removing almost all Ce from solution (evidenced by characteristic Ce depletions in calcite throughout this zone). Extreme Ce removal may be a result of Ce oxidation (Ce 3+ → Ce 4+ ) at the surfaces of some Mn oxides, particularly rancieite. Higher Sr contents and lack of Ce depletions in the deeper Mn calcites reflect different ages, origins, and transport systems. The calcite record of lanthanide and Sr transport in the UZ shows that minor minerals (clays and zeolites) and even trace minerals (Mn oxides) will affect the compositions of groundwaters that flow over distances greater than a few tens of meters. 43 refs., 8 figs., 4 tabs

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.

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

International Nuclear Information System (INIS)

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, SiO 2 , smectite and degasses CO 2 . 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 CO 2 . Concomitantly, there is precipitation of calcite, smectite, SiO 2 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.)

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

International Nuclear Information System (INIS)

Bates, J.K.; Buck, E.C.; Ebert, W.L.; Luo, J.S.; Tam, S.W.

1998-01-01

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/(m 2 · d). The rate between seven and 70 days decreased to 0.009 g/(m 2 · 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/(m 2 · 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/(m 2 · d) and the rate after phase formation was about 0.20 g/(m 2 · 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

Alteration of borosilicate glass under water saturated condition

International Nuclear Information System (INIS)

Tsukimura, K.; Matsuhisa, Y.; Kanai, Y.; Hirai, H.

1991-01-01

In the long term of the high-level nuclear waste disposal, the dissolving rates of radionuclides from the waste will be controlled by crystalline phases secondarily formed in the borosilicate glass by reaction with ground water. We have determined the crystalline phases formed from borosilicate glass in a hydrothermal experiment. Borosilicate glass powder (50 mg, Si 40 B 20 Al 4 Li 12 Na 14 K 3 Ca 2 Fe 5 O 140 ) and 200 ml of water were reacted at 300degC and 300 bars for 2 weeks with a cold-seal type hydrothermal high pressure apparatus. After the reaction the liquid phase was analyzed with atomic absorption spectroscopy and the solid phases with x-ray powder diffraction and analytical electron microscopy. The liquid phase contains 58 % of Na, 14 % of Li and 11 % of K but less than 1 % of Ca and Fe. The solid phases were found to be zeolite and smectite. The zeolite is isostructural with analcime Na 2 Al 2 (SiO 3 ) 4 · 2H 2 O or wairakite CaAl 2 (SiO 3 ) 4 · 2H 2 O and contains Ca and Si as major constituents but does not contain Al. Although no direct analytical evidence is available, logical induction of the experimental results indicates that the chemical composition of the zeolite is CaB 2 (SiO 3 ) 4 . The remaining x-ray powder diffraction peaks are same as those of smectite Na 06.7 (Al 3.33 Mg 0.67 )Si 8 O 20 (OH) 4 . However, since our starting material was free of Mg, and Na was not detected by AEM, the smectite may contain Fe instead of Mg, and Li instead of Na. (author)

Why is Dawsonite Absent in CO2 Charged Reservoirs?

International Nuclear Information System (INIS)

Hellevang, H.; Declercq, J.; Aagaard, P.

2011-01-01

Growth of the sodium-aluminium-hydroxy carbonate dawsonite (NaAl(OH) 2 CO 3 ) after charging saline aquifers with CO 2 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 CO 2 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, CO 2 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 CO 2 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

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)

Immobilization of simulated low and intermediate level waste in alkali-activated slag-fly ash-metakaolin hydroceramics

Energy Technology Data Exchange (ETDEWEB)

Wang, Jin, E-mail: wjin761026@163.com [State Key Laboratory Cultivation Base for Nonmetal Composite and Functional Materials, Southwest University of Science and Technology, Mianyang 621010, Sichuan (China); School of Materials Science and Engineering, Southwest University of Science and Technology, Mianyang 621010, Sichuan (China); Wang, Jun-xia; Zhang, Qin [School of Materials Science and Engineering, Southwest University of Science and Technology, Mianyang 621010, Sichuan (China); Li, Yu-xiang [State Key Laboratory Cultivation Base for Nonmetal Composite and Functional Materials, Southwest University of Science and Technology, Mianyang 621010, Sichuan (China); School of Materials Science and Engineering, Southwest University of Science and Technology, Mianyang 621010, Sichuan (China)

2016-04-15

Highlights: • Evaluation of the suitability of ASFMH for solidifying simulated S-LILW. • The introduction of S-LILW avails forming zeolitic phases of ASFMH waste forms. • The ASFMH waste forms have low leachability and high compressive strength. - Abstract: In the current study, the alkali-activated slag-fly ash-metakaolin hydroceramic (ASFMH) waste forms for immobilizing simulated low and intermediate level waste (S-LILW) were prepared by hydrothermal process. The crystalline phase compositions, morphology, compressive strength and aqueous stability of S-LILW ASFMH waste forms were investigated. The results showed that the main crystalline phases of S-LILW ASFMH waste forms were analcime and zeolite NaP1. The changes of Si/Al molar ratio (from 1.7 to 2.2) and Ca/Al molar ratio (from 0.15 to 0.35) had little effect on the phase compositions of S-LILW ASFMH waste forms. However, the hydrothermal temperature, time as well as the content of S-LILW (from 12.5 to 37.5 wt%) had a major impact on the phase compositions. The compressive strength of S-LILW ASFMH waste forms was not less than 20 MPa when the content of S-LILW reached 37.5 wt%. In addition, the aqueous stability testing was carried out using the standard MCC-1 static leach test method; the normalized elemental leach rates of Sr and Cs were fairly constant in a low value below 5 × 10{sup −4} g m{sup −2} d{sup −1} and 3 × 10{sup −4} g m{sup −2} d{sup −1} after 28 days, respectively. It is indicated that ASFMH waste form could be a potential host for safely immobilizing LILW.

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

Raman-Mössbauer-XRD studies of selected samples from "Los Azulejos" outcrop: A possible analogue for assessing the alteration processes on Mars

Science.gov (United States)

Lalla, E. A.; Sanz-Arranz, A.; Lopez-Reyes, G.; Sansano, A.; Medina, J.; Schmanke, D.; Klingelhoefer, G.; Rodríguez-Losada, J. A.; Martínez-Frías, J.; Rull, F.

2016-06-01

The outcrop of "Los Azulejos" is visible at the interior of the Cañadas Caldera in Tenerife Island (Spain). It exhibits a great variety of alteration processes that could be considered as terrestrial analogue for several geological processes on Mars. This outcrop is particularly interesting due to the content of clays, zeolite, iron oxides, and sulfates corresponding to a hydrothermal alteration catalogued as "Azulejos" type alteration. A detailed analysis by portable and laboratory Raman systems as well as other different techniques such as X-ray diffraction (XRD) and Mössbauer spectroscopy has been carried out (using twin-instruments from Martian lander missions: Mössbauer spectrometer MIMOS-II from the NASA-MER mission of 2001 and the XRD diffractometer from the NASA-MSL Curiosity mission of 2012). The mineral identification presents the following mineral species: magnetite, goethite, hematite, anatase, rutile, quartz, gregoryite, sulfate (thenardite and hexahydrite), diopside, feldspar, analcime, kaolinite and muscovite. Moreover, the in-situ Raman and Micro-Raman measurements have been performed in order to compare the capabilities of the portable system specially focused for the next ESA Exo-Mars mission. The mineral detection confirms the sub-aerial alteration on the surface and the hydrothermal processes by the volcanic fluid circulations in the fresh part. Therefore, the secondary more abundant mineralization acts as the color agent of the rocks. Thus, the zeolite-illite group is the responsible for the bluish coloration, as well as the feldspars and carbonates for the whitish and the iron oxide for the redish parts. The XRD system was capable to detect a minor proportion of pyroxene, which is not visible by Raman and Mössbauer spectroscopy due to the "Azulejos" alteration of the parent material on the outcrop. On the other hand, Mössbauer spectroscopy was capable of detecting different types of iron-oxides (Fe3+/2+-oxide phases). These analyses

Predictive hydrogeochemical modelling of bauxite residue sand in field conditions.

Science.gov (United States)

Wissmeier, Laurin; Barry, David A; Phillips, Ian R

2011-07-15

The suitability of residue sand (the coarse fraction remaining from Bayer's process of bauxite refining) for constructing the surface cover of closed bauxite residue storage areas was investigated. Specifically, its properties as a medium for plant growth are of interest to ensure residue sand can support a sustainable ecosystem following site closure. The geochemical evolution of the residue sand under field conditions, its plant nutrient status and soil moisture retention were studied by integrated modelling of geochemical and hydrological processes. For the parameterization of mineral reactions, amounts and reaction kinetics of the mineral phases natron, calcite, tricalcium aluminate, sodalite, muscovite and analcime were derived from measured acid neutralization curves. The effective exchange capacity for ion adsorption was measured using three independent exchange methods. The geochemical model, which accounts for mineral reactions, cation exchange and activity corrected solution speciation, was formulated in the geochemical modelling framework PHREEQC, and partially validated in a saturated-flow column experiment. For the integration of variably saturated flow with multi-component solute transport in heterogeneous 2D domains, a coupling of PHREEQC with the multi-purpose finite-element solver COMSOL was established. The integrated hydrogeochemical model was applied to predict water availability and quality in a vertical flow lysimeter and a cover design for a storage facility using measured time series of rainfall and evaporation from southwest Western Australia. In both scenarios the sand was fertigated and gypsum-amended. Results show poor long-term retention of fertilizer ions and buffering of the pH around 10 for more than 5 y of leaching. It was concluded that fertigation, gypsum amendment and rainfall leaching alone were insufficient to render the geochemical conditions of residue sand suitable for optimal plant growth within the given timeframe. The

Provenance analysis and thermo-dynamic studies of multi-type Holocene duricrusts (1700 BC) in the Sua Salt Pan, NE Botswana

Science.gov (United States)

Dill, Harald G.; Dohrmann, R.; Kaufhold, S.; Techmer, A.

2014-08-01

Multi-type duricrusts, composed of silcretes, calcretes, halcretes and sulcretes developed during the Holocene at the northern rim of the Sua Salt Pan, NE Botswana. They were investigated for their light (quartz/chalcedony, feldspar, analcime, clinoptilolite, calcite, kaolinite/halloysite, illite-smectite mixed-layers, halite) and heavy minerals (baryte, clinozoisite-epidote s.s.s., amphibole, corundum, tourmaline, ilmenite, rutile, sphene, kyanite, andalusite, staurolite, garnet, zircon, apatite, monazite, cassiterite, garnet, biotite) using petrographic microscopy, X-ray fluorescence and diffraction analyses, radio-carbon dating, scanning electron microscopy equipped with an EDX-system, cation exchange capacity and infrared spectroscopy. Detrital minerals predominantly derived from the erosion of rocks belonging to the Archaean Basement Complex, the Stormberg Volcanites and the Kalahari sediments. Of particular interest to exploration geologists, geikielite-enriched ilmenite fragments are a hint to kimberlitic pipes. Biodetritus was derived from invertebrates and from vertebrates (fish bones?). A man-made impact on the heavy mineral suite has to be invoked from small fragments of cassiterite fragments that derived from processing of sulfidic and pegmatitic Sn-bearing ore. In the salt-pan-derived duricrusts mainly the aeolian and to a lesser degree fluvial inputs were responsible for the concentration of clasts in these multi-type duricrusts. Moreover, their variegated mineralogy enables us to constrain the physical-chemical regime, prevalently as to the pH and the chemical composition of the major constituents. All duricrusts developed in a self-sufficient chemically closed system where quartz and feldspar provided the elements Si, Na, K, Ca, and Ba to produce the encrustations. The spatial and temporal trend in the Sua Salt Pan rim encrustations may be described as follows: (1) sulcrete-silcretes, (2) silcretes with kaolinite-group minerals towards more recent

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 (-18.8) close to the SAG outcrop. This is consistent with a conceptual geochemical model of the SAG, suggesting dissolution of calcite

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

Geochemical Modeling of ILAW Lysimeter Water Extracts

Energy Technology Data Exchange (ETDEWEB)

Cantrell, Kirk J. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

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 K_sp) 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

Regional paleohydrologic and paleoclimatic settings of wetland/lacustrine depositional systems in the Morrison Formation (Upper Jurassic), Western Interior, USA

Science.gov (United States)

Dunagan, S.P.; Turner, C.E.

2004-01-01

and shoreline deposits. Marginal lacustrine deposits include ooid and skeletal packstone-grainstone, siltstone, and sandstone. Distal lacustrine units are skeletal mudstone-wackestone, microbialites, and laminated (siliciclastic) mudstone. Differentiation between wetlands and distal lacustrine units is not always possible. Palustrine features, Magadi-type chert (MTC), and evaporites record episodes of increased aridity and exposure. Farther upstream, during deposition of the upper part of the Brushy Basin Member, the ancestral Uncompahgre Uplift imposed a barrier to shallow, eastward-flowing groundwater that discharged into the San Juan/Paradox Basin on the upstream side of the uplift. This created the closed hydrologic setting necessary for development of an alkaline-saline wetland/lacustrine complex ("Lake" T'oo'dichi'). Silicic volcanic ash, delivered by prevailing winds from calderas west and southwest of the basin, contributed to the pore-water evolution in the sediments. A distinctive lateral hydrogeochemical gradient, reflecting increasing salinity and alkalinity in the pore waters, altered the ash to a variety of authigenic minerals that define concentric zones within the basin. The basinward progression of diagenetic mineral zones is smectite???clinoptilolite???analcime ??potassium feldspar???albite. The groundwater-fed wetlands were shallow and frequently evaporated to dryness. Scarce laminated gray mudstone beds record distinct episodes of freshwater lacustrine deposition that resulted from intermittent streams that carried detritus well out into the basin. ?? 2004 Elsevier B.V. All rights reserved.

Cataclastic rocks of the San Gabriel fault—an expression of deformation at deeper crustal levels in the San Andreas fault zone

Science.gov (United States)

Anderson, J. Lawford; Osborne, Robert H.; Palmer, Donald F.

1983-10-01

The San Gabriel fault, a deeply eroded late Oligocene to middle Pliocene precursor to the San Andreas, was chosen for petrologic study to provide information regarding intrafault material representative of deeper crustal levels. Cataclastic rocks exposed along the present trace of the San Andreas in this area are exclusively a variety of fault gouge that is essentially a rock flour with a quartz, feldspar, biotite, chlorite, amphibole, epidote, and Fe-Ti oxide mineralogy representing the milled-down equivalent of the original rock (Anderson and Osborne, 1979; Anderson et al., 1980). Likewise, fault gouge and associated breccia are common along the San Gabriel fault, but only where the zone of cataclasis is several tens of meters wide. At several localities, the zone is extremely narrow (several centimeters), and the cataclastic rock type is cataclasite, a dark, aphanitic, and highly comminuted and indurated rock. The cataclastic rocks along the San Gabriel fault exhibit more comminution than that observed for gouge along the San Andreas. The average grain diameter for the San Andreas gouge ranges from 0.01 to 0.06 mm. For the San Gabriel cataclastic rocks, it ranges from 0.0001 to 0.007 mm. Whereas the San Andreas gouge remains particulate to the smallest grain-size, the ultra-fine grain matrix of the San Gabriel cataclasite is composed of a mosaic of equidimensional, interlocking grains. The cataclastic rocks along the San Gabriel fault also show more mineralogiec changes compared to gouge from the San Andreas fault. At the expense of biotite, amphibole, and feldspar, there is some growth of new albite, chlorite, sericite, laumontite, analcime, mordenite (?), and calcite. The highest grade of metamorphism is laumontite-chlorite zone (zeolite facies). Mineral assemblages and constrained uplift rates allow temperature and depth estimates of 200 ± 30° C and 2-5 km, thus suggesting an approximate geothermal gradient of ~50°C/km. Such elevated temperatures imply a

Uranium geology and chemistry, programme and book of abstracts

International Nuclear Information System (INIS)

Patrice Bruneton; Cathelineau, Michel; Richard, Antonin; Mercadier, Julien; Boiron, Marie-Christine; Cuney, Michel; Beaufort, D.; Patrier, P.; Goncalves, Philippe; Trap, Pierre; Van Lichtervelde, Marieke; Jeanneret, Pauline; Marquer, Didier; Feybesse, Jean-Louis; Paquette, Jean-Louis; Mercadier, Julien; Annesley, Irvine R.; Austmann, Christine L.; Creighton, Steve; Eglinger, Aurelien; Vanderhaeghe, Olivier; Andre-Mayer, Anne-Sylvie; Cuney, Michel; Goncalves, Philippe; Durand, Cyril; Feybesse, Jean-Louis; Zeyen, Hermann; Beres, Jan; Pessel, Marc; Gaffet, Stephane; Rousset, Dominique; Senechal, Guy; Dargent, Maxime; Dubessy, Jean; Caumon, Marie-Camille; Trung, Chinh-Nguyen; Richard, Antonin; Montel, Jean-Marc; Peiffert, Chantal; Leborgne, Romain; Seydoux-Guillaume, Anne-Magali; Montel, J.M.; Bingen, B.; Bosse, V.; De Parseval, Ph.; Janots, Emilie; Wirth, Richard; Reiller, Pascal E.; Marang, Laura; Jouvin, Delphine; Benedetti, Marc F.; Clavier, N.; Costin, D.T.; Mesbah, A.; Dacheux, N.; Poinssot, C.; Raimbault, Louis; Mercadier, Julien; Cuney, Michel; Moncoffre, Nathalie; Marchand, Benoit; Perrat-Mabillon, Angela; Gine, A.; Saint-Bezar, B.; Benedicto, A.; Wattinne, A.; Andre, G.; Bonnetti, Christophe; Bourlange, Sylvain; Malartre, Fabrice; Benedicto, Antonio; Liu, Xiaodong; Cretaz, F.; Szenknect, S.; Descostes, M.; Dacheux, N.; Othmane, Guillaume; Allard, Thierry; Menguy, Nicolas; Vercouter, Thomas; Morin, Guillaume; Esteve, Imene; Calas, Georges; Fayek, Mostafa; Barbarand, Jocelyn; Drot, Romuald; Grare, Alexis; Reyx, Jean; Pagel, Maurice; Brouand, Marc; Zakari, Aziz; Bidaud, Adrien; Toe, Wilfried; Milesi, Jean-Pierre; Carrouee, Simon; Moyen, Jean-Francois; Schmitt, Jean-Michel; Brouand, Marc; Bouzid, Majda; Langlais, Valerie; Hocquet, Sebastien; Munara, A.; Boulvais, P.; Carpentier, C.; Ajjabou, Leila; Ledru, Patrick; Fiet, Nicolas; Hocquet, Sebastien; Royer, Jean-Jacques; Fiet, N.; Oppeneau, T.; Berestnev, N.; Merembayev, T.; Parize, Olivier; Aouami, I.; Nedjari, A.; Mahaman, T.; Sanguinetti, H.; Uri, Freddy; Beaufort, Daniel; Riegler, Thomas; Lescuyer, Jean-Luc; Wollenberg, Peter; Dardel, Jacques; Bourgeois, Damien; Maynadie, Jerome; Meyer, Daniel; Courtaud, B.; Auger, F.; Thiry, J.; Fakhi, S.; Fait, E.; Outayad, R.; Mouflih, M.; Voque Romero, I.; Manjon, Guillermo; Ben Mansour, M.; Bouih, A.; Nourreddine, A.; El Hadi, H.; Mokhtari, Hamid; Gourgiotis, Alkiviadis; Bassot, Sylvain; Simonucci, Caroline; Diez, Olivier; Mifsud, Aurelie; Martin-Garin, Arnaud; Coppin, Frederic; Dejeant, Adrien; Galoisy, Laurence; Calas, Georges; Phrommavanh, Vannapha; Descostes, Michael; Wattine-Morice, Aurelia; Belieres, Michel; Ben Simon, Rose; Schmitt, Jean-Michel; Thiry, Medard; Megneng, Melissa; Orberger, Beate; Hofmann, Axel; Wirth, Richard; Dumas, Paule; Sandt, Christophe; Hicks, Nigel; Tudryn, Alina; Tartese, Romain; Boulvais, Philippe; Poujol, Marc

2011-11-01

sand 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)

Major and trace elements in Mahogany zone oil shale in two cores from the Green River Formation, piceance basin, Colorado

Science.gov (United States)

Tuttle, M.L.; Dean, W.E.; Parduhn, N.L.

1983-01-01

and dilution of most trace elements as pointed out in several previous studies. Q-mode factor modeling is a statistical method used to group samples on the basis of compositional similarities. Factor end-member samples are chosen by the model. All other sample compositions are represented by varying proportions of the factor end-members and grouped as to their highest proportion. The compositional similarities defined by the Q-mode model are helpful in understanding processes controlling multi-element distributions. The models for each core are essentially identical. A four-factor model explains 70% of the variance in the CR-2 data and 64% of the O1-A data (the average correlation coefficients are 0. 84 and 0. 80, respectively). Increasing the number of factors above 4 results in the addition of unique instead of common factors. Table I groups the elements based on high factor-loading scores (the amount of influence each element has in defining the model factors). Similar elemental associations are found in both cores. Elemental abundances are plotted as a function of core depth using a five-point weighted moving average of the original data to smooth the curve (Figure 3 and 4). The plots are grouped according to the four factors defined by the Q-mode models and show similar distributions for elements within the same factor. Factor 1 samples are rich in most trace metals. High oil yield and the presence of illite characterize the end-member samples for this factor (3, 4) suggesting that adsorption of metals onto clay particles or organic matter is controlling the distribution of the metals. Precipitation of some metals as sulfides is possible (5). Factor 2 samples are high in elements commonly associated with minerals of detrital or volcanogenic origin. Altered tuff beds and lenses are prevalent within the Mahogany zone. The CR-2 end-member samples for this factor contain analcime (3) which is an alteration product within the tuff beds of the Green River Formation. Th

Long-Term CO2 Exposure Experiments - Geochemical Effects on Brine-Saturated Reservoir Sandstone

Science.gov (United States)

Fischer, Sebastian; Zemke, Kornelia; Liebscher, Axel; Wandrey, Maren

2010-05-01

The injection of CO2 into deep saline aquifers is the most promising strategy for the reduction of CO2 emissions to the atmosphere via long-term geological storage. The study is part of the CO2SINK project conducted at Ketzin, situated 40 km west of Berlin. There, food grade CO2 has been pumped into the Upper Triassic Stuttgart Formation since June 2008. The main objective of the experimental program is to investigate the effects of long-term CO2 exposure on the physico-chemical properties of the reservoir rock. To achieve this goal, core samples from observation well Ktzi 202 have been saturated with synthetic brine and exposed to CO2 in high quality steel autoclaves at simulated reservoir P-T-conditions of 5.5 MPa and 40 ° C. The synthetic brine had a composition representative of the formation fluid (Förster et al., 2006) of 172.8 g/l NaCl, 8.0 g/l MgCl2×2H2O, 4.8 g/l CaCl2×2H2O and 0.6 g/l KCl. After 15 months, the first set of CO2-exposed samples was removed from the pressure vessels. Thin sections, XRD, SEM as well as EMP data were used to determine the mineralogical features of the reservoir rocks before and after the experiments. Additionally, NMR relaxation and MP was performed to measure poroperm and pore size distribution values of the twin samples. The analyzed samples are fine- to medium grained, moderately well- to well sorted and weakly consolidated sandstones. Quartz and plagioclase are the major components, while K-feldspar, hematite, white & dark mica, chlorite and illite are present in minor and varying amounts. Cements are composed of analcime, dolomite and anhydrite. Some samples show mm- to cm-scale cross-beddings. The laminae comprise lighter, quartz- and feldspar-dominated layers and dark-brownish layers with notably less quartz and feldspars. The results are consistent with those of Blaschke et al. (2008). The plagioclase composition indicates preferred dissolution of the Ca-component and a trend toward albite-rich phases or even pure

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

Energy Technology Data Exchange (ETDEWEB)

Ebert, W. L.; Chemical Engineering

2006-09-30

directly. The 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{sup -5}, 2 x 10{sup -8}, and 1 x 10{sup -7} M in tests solutions near pH 3.7 to about 1 x 10{sup -9}, 8 x 10{sup -10}, and 1 x 10{sup -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

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