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Conflict Minerals and Resource Extraction: Dodd-Frank, SEC Regulations, and Legal Challenges

Description: This report discusses the two sections of the Dodd-Frank Wall Street Reform and Protection Act (Dodd-Frank) that require the Securities and Exchange Commission (SEC or Commission) to issue regulations to make public the involvement of U.S. companies in conflict minerals and in resource extraction payments.
Date: December 2, 2014
Creator: Seitzinger, Michael V. & Ruane, Kathleen Ann
Partner: UNT Libraries Government Documents Department

Conflict Minerals and Resource Extraction: Dodd-Frank, SEC Regulations, and Legal Challenges

Description: This report discusses the two sections of the Dodd-Frank Wall Street Reform and Protection Act (Dodd-Frank) that require the Securities and Exchange Commission (SEC or Commission) to issue regulations to make public the involvement of U.S. companies in conflict minerals and in resource extraction payments.
Date: October 15, 2014
Creator: Seitzinger, Michael V. & Ruane, Kathleen Ann
Partner: UNT Libraries Government Documents Department

Minerals Price Increases and Volatility: Causes and Consequences

Description: This report discusses China's efforts to improve and increase its access to foreign mineral resources, which may have the effect of raising prices for U.S. domestic industrial users. The report examines in detail the relationship between prices, production, and availability of selected metal minerals essential to the U.S. economy. It focuses on iron ore, aluminum (bauxite/alumina), copper, manganese, molybdenum (moly), zinc, platinum group metals (PGMs), and uranium.
Date: October 3, 2008
Creator: Cooney, Stephen; Pirog, Robert; Folger, Peter; Humphries, Marc & Nanto, Dick K.
Partner: UNT Libraries Government Documents Department

Effect of different glasses in glass bonded zeolite

Description: A mineral waste form has been developed for chloride waste salt generated during the pyrochemical treatment of spent nuclear fuel. The waste form consists of salt-occluded zeolite powders bound within a glass matrix. The zeolite contains the salt and immobilizes the fission products. The zeolite powders are hot pressed to form a mechanically stable, durable glass bonded zeolite. Further development of glass bonded zeolite as a waste form requires an understanding of the interaction between the glass and the zeolite. Properties of the glass that enhance binding and durability of the glass bonded zeolite need to be identified. Three types of glass, boroaluminosilicate, soda-lime silicate, and high silica glasses, have a range of properties and are now being investigated. Each glass was hot pressed by itself and with an equal amount of zeolite. MCC-1 leach tests were run on both. Soda-lime silicate and high silica glasses did not give a durable glass bonded zeolite. Boroaluminosilicate glasses rich in alkaline earths did bind the zeolite and gave a durable glass bonded zeolite. Scanning electron micrographs suggest that the boroaluminosilicate glasses wetted the zeolite powders better than the other glasses. Development of the glass bonded zeolite as a waste form for chloride waste salt is continuing.
Date: May 1, 1995
Creator: Lewis, M.A.; Ackerman, J.P. & Verma, S.
Partner: UNT Libraries Government Documents Department

Appalachian Clean Coal Technology Consortium. Technical progress report, October 10, 1994--December 31, 1994

Description: The Appalachian Clean Coal Technology Consortium (ACCTC) has been established to help U.S. Coal producers, particularly those in the Appalachian region, increase the production of lower-sulfur coal. The cooperative research conducted as part of the consortium activities will help utilities meet the emissions standards established by the 1990 Clean Air Act Amendments, enhance the competitiveness of U.S. coals in the world market, create jobs in economically-depressed coal producing regions, and reduce U.S. dependence on foreign energy supplies. The consortium has three charter members, including Virginia Polytechnic Institute and State University, West Virginia University, and the University of Kentucky. The Consortium also includes industry affiliate members that form an Advisory Committee. Affiliate members currently include AMVEST Minerals; Arch Minerals Corp.; A.T. Massey Coal Co.; Carpco, Inc.; CONSOL Inc.; Cyprus Amax Coal Co.; Pittston Coal Management Co.; and Roberts & Schaefer Company. First year activites are focused on dewatering and modeling of spirals.
Date: June 26, 1995
Creator: Feeley, T.J. III
Partner: UNT Libraries Government Documents Department

Predictive modelling of boiler fouling. Final report.

Description: A spectral element method embodying Large Eddy Simulation based on Re- Normalization Group theory for simulating Sub Grid Scale viscosity was chosen for this work. This method is embodied in a computer code called NEKTON. NEKTON solves the unsteady, 2D or 3D,incompressible Navier Stokes equations by a spectral element method. The code was later extended to include the variable density and multiple reactive species effects at low Mach numbers, and to compute transport of large particles governed by inertia. Transport of small particles is computed by treating them as trace species. Code computations were performed for a number of test conditions typical of flow past a deep tube bank in a boiler. Results indicate qualitatively correct behavior. Predictions of deposition rates and deposit shape evolution also show correct qualitative behavior. These simulations are the first attempts to compute flow field results at realistic flow Reynolds numbers of the order of 10{sup 4}. Code validation was not done; comparison with experiment also could not be made as many phenomenological model parameters, e.g., sticking or erosion probabilities and their dependence on experimental conditions were not known. The predictions however demonstrate the capability to predict fouling from first principles. Further work is needed: use of large or massively parallel machine; code validation; parametric studies, etc.
Date: December 31, 1990
Creator: Chatwani, A
Partner: UNT Libraries Government Documents Department

A comparative study of radiation damage in Al{sub 2}O{sub 3}, FeTiO{sub 3}, and MgTiO{sub 3}

Description: Oriented single crystals of synthetic alpha-alumina ({alpha}-Al{sub 2}O{sub 3}), geikielite (MgTiO{sub 3}) natural ilmenite (FeTiO{sub 3}) were irradiated with 200 keV argon ions under cryogenic conditions (100 K) to assess their damage response. Using Rutherford backscattering spectrometry combined with ion channeling techniques, it was found that ilmenite amorphized readily at doses below 5{times}10{sup 14}, alumina amorphized at a dose of 1-2{times}{sup 15}, and geikielite was amorphized at {approximately}2{times}10{sup 15} Ar cm{sup {minus}2}. The radiation damage response of the ilmenite crystal may be complicated by the presence of hematite exsolution lamellae and the experimentally induced oxidation of iron. The relative radiation-resistance of geikielite holds promise for similar behavior in other Mg-Ti oxides.
Date: December 31, 1995
Creator: Mitchell, J.N.; Yu, Ning; Sickafus, K.E.; Nastasi, M.; Taylor, T.N.; McClellan, K.J. et al.
Partner: UNT Libraries Government Documents Department

EQ3/6, a software package for geochemical modeling of aqueous systems: Package overview and installation guide (Version 7.0)

Description: EQ3/6 is a software package for geochemical modeling of aqueous systems. This report describes version 7.0. The major components of the package include: EQ3NR, a speciation-solubility code; EQ6, a reaction path code which models water/rock interaction or fluid mixing in either a pure reaction progress mode or a time mode; EQPT, a data file preprocessor, EQLIB, a supporting software library; and five supporting thermodynamic data files. The software deals with the concepts of thermodynamic equilibrium, thermodynamic disequilibrium, and reaction kinetics. The five supporting data files contain both standard state and activity coefficient-related data. Three support the use of the Davies or B-dot equations for the activity coefficients; the other two support the use of Pitzer`s equations. The temperature range of the thermodynamic data on the data files varies from 25{degree}C only to 0--300{degree}C. EQPT takes a formatted data file (a data0 file) and writes an unformatted near-equivalent called a datal file, which is actually the form read by EQ3NR and EQ6. EQ3NR is useful for analyzing groundwater chemistry data, calculating solubility limits, and determining whether certain reactions are in states of partial equilibrium or disequilibrium. It is also required to initialize an EQ6 calculation. EQ6 models the consequences of reacting an aqueous solution with a set of reactants which react irreversibly. It can also model fluid mixing and the consequences of changes in temperature. This code operates both in a pure reaction progress frame and in a time frame.
Date: September 14, 1992
Creator: Wolery, T.J.
Partner: UNT Libraries Government Documents Department

EQ6, a computer program for reaction path modeling of aqueous geochemical systems: Theoretical manual, user`s guide, and related documentation (Version 7.0); Part 4

Description: EQ6 is a FORTRAN computer program in the EQ3/6 software package (Wolery, 1979). It calculates reaction paths (chemical evolution) in reacting water-rock and water-rock-waste systems. Speciation in aqueous solution is an integral part of these calculations. EQ6 computes models of titration processes (including fluid mixing), irreversible reaction in closed systems, irreversible reaction in some simple kinds of open systems, and heating or cooling processes, as well as solve ``single-point`` thermodynamic equilibrium problems. A reaction path calculation normally involves a sequence of thermodynamic equilibrium calculations. Chemical evolution is driven by a set of irreversible reactions (i.e., reactions out of equilibrium) and/or changes in temperature and/or pressure. These irreversible reactions usually represent the dissolution or precipitation of minerals or other solids. The code computes the appearance and disappearance of phases in solubility equilibrium with the water. It finds the identities of these phases automatically. The user may specify which potential phases are allowed to form and which are not. There is an option to fix the fugacities of specified gas species, simulating contact with a large external reservoir. Rate laws for irreversible reactions may be either relative rates or actual rates. If any actual rates are used, the calculation has a time frame. Several forms for actual rate laws are programmed into the code. EQ6 is presently able to model both mineral dissolution and growth kinetics.
Date: October 9, 1992
Creator: Wolery, T.J. & Daveler, S.A.
Partner: UNT Libraries Government Documents Department

Characterization of Climax granite ground water

Description: The Climax ground water fails to match the commonly held views regarding the nature of deep granitic ground waters. It is neither dilute nor in equilibrium with the granite. Ground-water samples were taken for chemical analysis from five sites in the fractured Climax granite at the Nevada Test Site. The waters are high in total dissolved solids (1200 to 2160 mg/L) and rich in sodium (56 to 250 mg/L), calcium (114 to 283 mg/L) and sulfate (325 to 1060 mg/L). Two of the samples contained relatively high amounts of uranium (1.8 and 18.5 mg/L), whereas the other three contained uranium below the level of detection (< 0.1 mg/L). The pH is in the neutral range (7.3 to 8.2). The differences in composition between samples (as seen in the wide range of values for the major constituents and total dissolved solids) suggest the samples came from different, independent fracture systems. However, the apparent trend of increasing sodium with depth at the expense of calcium and magnesium suggests a common evolutionary chemical process, if not an interconnected system. The waters appear to be less oxidizing with depth (+ 410 mV at 420 m below the surface vs + 86 mV at 565 m). However, with Eh measurements on only two samples, this correlation is questionable. Isotopic analyses show that the waters are of meteoric origin and that the source of the sulfate is probably the pyrite in the fracture-fill material. Analysis of the measured water characteristics using the chemical equilibrium computer program EQ3 indicates that the waters are not in equilibrium with the local mineral assemblage. The solutions appear to be supersaturated with respect to the mineral calcite, quartz, kaolinite, muscovite, k-feldspar, and many others.
Date: August 1, 1982
Creator: Isherwood, D.; Harrar, J. & Raber, E.
Partner: UNT Libraries Government Documents Department

Geochemical analysis of fluid mineral relations in the Tiwi Geothermal Field, Philippines

Description: Geochemical modeling simulations are being used to examine the source of the reservoir fluids in the Tiwi geothermal field and to evaluate the chemical and physical processes responsible for producing observed vein parageneses. Such information can be used to trace the evolution of the Tiwi geothermal field through time. The React geochemical modeling code was used to simulate the effects of isothermal and isoenthalpic boiling, conductive cooling and heating, and incorporation of condensed steam, on fluids from the Matalibong area. Predicted mineral stabilities were used to identify mineral indicators for each process. Calcite and anhydrite precipitation were favored by conductive heating, while illite precipitation was favored when condensed steam was added to the reservoir fluid. Reconstructed downhole fluids from borehole Mat-25 are acidic and are consistent with the presence of illite as the latest alteration mineral in veins. The processes of isothermal and isoenthalpic boiling could be differentiated from conductive cooling by the presence of epidote and/or calcite during boiling, and illite during cooling. Both boiling and cooling favored precipitation of quartz, K-feldspar, wairakite, and pyrite. Ratios of Na, Cl, and Br in waters from the Matalibong are relative to seawater indicate a significant component of seawater in reservoir fluids.
Date: January 1, 1997
Creator: Bruton, C.J.; Moore, J.N. & Powell, T.S.
Partner: UNT Libraries Government Documents Department

The testing of thermal-mechanical-hydrological-chemical processes using a large block

Description: The radioactive decay heat from nuclear waste packages may, depending on the thermal load, create coupled thermal-mechanical-hydrological-chemical (TMHC) processes in the near-field environment of a repository. A group of tests on a large block (LBT) are planned to provide a timely opportunity to test and calibrate some of the TMHC model concepts. The LBT is advantageous for testing and verifying model concepts because the boundary conditions are controlled, and the block can be characterized before and after the experiment. A block of Topopah Spring tuff of about 3 {times} 3 {times} 4.5 m will be sawed and isolated at Fran Ridge, Nevada Test Site. Small blocks of the rock adjacent to the large block will be collected for laboratory testing of some individual thermal-mechanical, hydrological, and chemical processes. A constant load of about 4 MPa will be applied to the top and sides of the large block. The sides will be sealed with moisture and thermal barriers. The large block will be heated with one heater in each borehole and guard heaters on the sides so that a dry-out zone and a condensate zone will exist simultaneously. Temperature, moisture content, pore pressure, chemical composition, stress and displacement will be measured throughout the block during the heating and cool-down phases. The results from the experiments on small blocks and the tests on the large block will provide a better understanding of some concepts of the coupled TMHC processes.
Date: January 1, 1994
Creator: Lin, W.; Wilder, D.G.; Blink, J.A.; Blair, S.C.; Buscheck, T.A.; Chesnut, D.A. et al.
Partner: UNT Libraries Government Documents Department

Radionuclide migration as a function of mineralogy

Description: The migration of radionuclides is studied as a function of mineralogy utilizing batch sorption and column experiments. The transport behavior of alkaline, alkaline-earth, and transition metals, and actinide species is studied in pure mineral separates. The solid phases utilized for these investigations are silicates, alumino-silicates, carbonates, and metal oxides and oxyhydroxides. The results of this effort are utilized to aid in the elucidation of the dominant chemical mechanisms of radionuclide migration, the prediction of radionuclide transport in conditions similar to those expected at the proposed high-level nuclear waste repository at Yucca Mountain, Nevada, and the identification of materials that act as natural geological barriers or that can be utilized as strong sorbers in engineered barriers. 9 refs., 2 figs., 2 tabs.
Date: February 1, 1991
Creator: Triay, I.R.; Mitchell, A.J. & Ott, M.A.
Partner: UNT Libraries Government Documents Department

Radionuclide migration laboratory studies for validation of batch sorption data

Description: Advective and diffusive migration experiments (within the Dynamic Transport Column Experiments and Diffusion Studies of the Yucca Mountain Site Characterization Project) involve utilizing crushed material, intact, and fractured tuff in order to test and improve (if necessary) transport models by experimentally observing the migration of sorbing and non-sorbing radionuclides on a laboratory scale. Performing a validation of the sorption data obtained with batch techniques (within the Batch Sorption Study) is an integral part of the mission of the Dynamic Transport Column Experiments and Diffusion Studies. In this paper the work scope of the radionuclide migration laboratory experiments (as they apply to validation of batch sorption data) is reviewed.
Date: December 31, 1991
Creator: Triay, I.R.; Mitchell, A.J. & Ott, M.A.
Partner: UNT Libraries Government Documents Department

Fracture-coating minerals in the Topopah Spring Member and upper tuff of Calico Hills from drill hole J-13

Description: Fracture-lining minerals from drill core in the Topopah Spring Member of the Paintbrush Tuff and the tuff of Calico Hills from water well J-13 were studied to identify the differences between these minerals and those seen in drill core USW G-4. In USW G-4 the static water level (SWL) occurs below the tuff of Calico Hills, but in J-13 the water table is fairly high in the Topopah Spring Member. There are some significant differences in fracture minerals between these two holes. In USW G-4 mordenite is a common fracture-lining mineral in the Topopah Spring Member, increasing in abundance with depth. Euhedral heulandite >0.1 mm in length occurs in fractures for about 20 m above the lower vitrophyre. In J-13, where the same stratigraphic intervals are below the water table, mordenite is uncommon and euhedral heulandite is not seen. The most abundant fracture coating in the Topopah Spring Member in J-13 is drusy quartz, which is totally absent in this interval in USW G-4. Though similar in appearance, the coatings in the vitrophyre have different mineralogy in the two holes. In USW G-4 the coatings are extremely fine grained heulandite and smectite. In J-13 the coatings are fine-grained heulandite, chabazite, and alkali feldspar. Chabazite has not been identified from any other hole in the Yucca Mountain area. Fractures in the tuff of Calico Hills have similar coatings in core from both holes. In J-13, as in USW G-4, the tuff matrix of the Topopah Spring Member is welded and devitrified and that of the tuff of Calico Hills is zeolitic. 11 refs., 10 figs., 5 tabs.
Date: February 1, 1989
Creator: Carlos, B.
Partner: UNT Libraries Government Documents Department

Measurement and control of pH in hydrothermal solutions

Description: Hydrogen-electrode concentration cells with liquid junction are routinely used to measure the pH of aqueous solutions from 0 to 300 C. Results include the dissociation constants of common acids and bases and the hydrolysis and complexation of metal ions in aqueous electrolytes over a wide range of salinities. Recently, we have utilized these cells to examine the sorption of H{sup +} on mineral surfaces, the solubility of minerals with continuous in situ pH measurement, and the thermal decompositon rates of organic acids.
Date: December 31, 1995
Creator: Wesolowski, D.J.; Palmer, D.A. & Mesmer, R.E.
Partner: UNT Libraries Government Documents Department

Impact of organic-mineral matter interactions on thermal reaction pathways for coal model compounds

Description: Coal is a complex, heterogeneous solid that includes interdispersed mineral matter. However, knowledge of organic-mineral matter interactions is embryonic, and the impact of these interactions on coal pyrolysis and liquefaction is incomplete. Clay minerals, for example, are known to be effective catalysts for organic reactions. Furthermore, clays such as montmorillonite have been proposed to be key catalysts in the thermal alteration of lignin into vitrinite during the coalification process. Recent studies by Hatcher and coworkers on the evolution of coalified woods using microscopy and NMR have led them to propose selective, acid-catalyzed, solid state reaction chemistry to account for retained structural integrity in the wood. However, the chemical feasibility of such reactions in relevant solids is difficult to demonstrate. The authors have begun a model compound study to gain a better molecular level understanding of the effects in the solid state of organic-mineral matter interactions relevant to both coal formation and processing. To satisfy the need for model compounds that remain nonvolatile solids at temperatures ranging to 450 C, model compounds are employed that are chemically bound to the surface of a fumed silica (Si-O-C{sub aryl}linkage). The organic structures currently under investigation are phenethyl phenyl ether (C{sub 6}H{sub 5}CH{sub 2}CH{sub 2}OC{sub 6}H{sub 5}) derivatives, which serve as models for {beta}-alkyl aryl ether units that are present in lignin and lignitic coals. The solid-state chemistry of these materials at 200--450 C in the presence of interdispersed acid catalysts such as small particle size silica-aluminas and montmorillonite clay will be reported. Initial focus will be on defining the potential impact of these interactions on coal pyrolysis and liquefaction.
Date: July 1, 1995
Creator: Buchanan, A.C. III; Britt, P.F. & Struss, J.A.
Partner: UNT Libraries Government Documents Department

Radiation-Induced Phase Transformations in Ilmenite-Group Minerals

Description: Transmission electron microscopy (TEM) is a powerful tool for characterizing and understanding radiation-induced structural changes in materials. We have irradiated single crystals of ilmenite (FeTiO{sub 3}) and geikielite (MgTiO{sub 3}) using ions and electrons to better understand the response of complex oxides to radiation. Ion irradiation experiments of bulk single crystals at 100 K show that ilmenite amorphized at doses of less than 1x10(exp15) Ar(2+)/sq cm and at a damage level in the peak damage region of 1 displacement per atom (dpa). Transmission electron microscopy and electron diffraction of a cross-sectioned portion of this crystal confirmed the formation of a 150 am thick amorphous layer. Geikielite proved to be more radiation resistant, requiring a flux of 2x10(exp 15) Xe(2+)/sq cm to induce amorphization at 100 K. This material did not amorphize at 470 K, despite a dose of 2.5 x10(exp 16) Xe(2+)/sq cm and a damage level as high as 25 dpa. Low temperature irradiations of electron- transparent crystals with 1 MeV Kr(+) also show that ilmenite amorphized after a damage level of 2.25 dpa at 175 K.Similar experiments on geikielite show that the microstructure is partially amorphous and partially crystalline after 10 dpa at 150 K. Concurrent ion and electron irradiation of both materials with 1 MeV Kr(+) and 0.9 MeV electrons produced dislocation loops in both materials, but no amorphous regions were formed. Differences in the radiation response of these isostructural oxides suggests that in systems with Mg-Fe solid solution, the Mg-rich compositions may be more resistant to structural changes.
Date: December 31, 1997
Creator: Mitchell, J. N.
Partner: UNT Libraries Government Documents Department

The Corrosion of UO2 Versus ThO2: a Quantum Mechanical Investigation

Description: Quantum mechanical surface energy calculations have been performed on both uranium dioxide (UO{sub 2}) and thorium dioxide (ThO{sub 2}) (111), (110), and (100) surfaces to determine their relative reactivities. While UO{sub 2} and ThO{sub 2} both have the fluorite structure Fm3m, they differ in that uranium has two dominant oxidation states, U{sup 4+} and U{sup 6+}, while thorium only has one, Th{sup 4+}. Furthermore, UO{sub 2} is an intrinsically weak p-type semi-conductor with a band gap of 2.14 eV (Killeen, 1980), while ThO{sub 2} is an insulator. Dissolution and spectroscopic studies indicate that UO{sub 2} and ThO{sub 2} have different solubilities (Sunder and Miller, 2000). We use the quantum mechanical program, CASTEP (CAmbridge Scientific Total Energy Package) to perform surface and adsorption energy calculations on the (111) surface of both materials, with specific attention to O, H{sub 2}O, and combined adsorption cases. UO{sub 2} and ThO{sub 2} bulk unit cells were optimized to find the most stable configuration of atoms. Surface slabs were ''cleaved'' from the relaxed bulk for each orientation, placed in a 10 {angstrom} vacuum gap in order to simulate a free surface and were optimized. Relative surface energy trends and atomic relaxation were compared between the surfaces of UO{sub 2} and ThO{sub 2}. The (111) surface is found to have the most energetically stable configuration of atoms in both cases, although ThO{sub 2} has higher surface energy values than UO{sub 2} on all three surfaces. The (111) surface slab is doubled in width in order to increase the number of surface sites, and different starting positions for adsorbates are tested in order to calculate the most energetically favorable adsorption sites. Adsorption energy results indicate that adsorption is more favorable on the UO{sub 2} (111) surface than the ThO{sub 2} (111) surface. Adsorption calculations are accompanied by partial ...
Date: January 11, 2005
Creator: Skomurski, F.N.; Shuller, L.C.; Becker, U. & Ewing, R.C.
Partner: UNT Libraries Government Documents Department

Suppression of fine ash formation in pulverized coal flames. Quarterly technical progress report No. 10, January 1, 1995--March 31, 1995

Description: The production of ash particles from coal combustion limits it`s use as a fuel. On mechanism by which small ash particles are formed is the generation of submicron aerosols through a vaporization/condensation mechanism. Previous work has shown that coal cleaning can lead to increased emissions of aerosols. This research will investigate the means or aerosol formation in coals and the effects that various methods of coal cleaning have on aerosol production, and whether or not cleaning can be performed in a manner that will not lend itself to aerosol formation.
Date: June 1, 1995
Creator: Kramlich, J.C.; Chenevert, B. & Park, J.
Partner: UNT Libraries Government Documents Department

Visual display of reservoir parameters affecting enhanced oil recovery. Quarterly report, April 1995--June 1995. 2nd Quarter, FY 1995

Description: This report describes the development of a Spatial Database Manager (SDBM) shell/interface which will provide information to users on how to collect, store, analyze, interpret, visualize and present data in an integrated reservoir characterization study. SDBM will provide access to various geologic, reservoir visual data via a well log interpretation program (Crocker Petrolog), mapping and cross section software ( the GeoGraphix Exploration System Workbench) and a volume visualization application. Data tables for geochemical and petrographic data, well logs, well header information, well production data, formation tops, and fault trace data have been completed. Spectral mineral data are currently being collected which will ultimately be used for identification of mineral assemblages. The geochemical program CHILLER is being used to model fluid-rock interactions and possibly porosity predictions.
Date: April 5, 1995
Creator: Wood, J.R.
Partner: UNT Libraries Government Documents Department

Analysis of mineral trapping for CO{sub 2} disposal in deep aquifers

Description: CO{sub 2} disposal into deep aquifers has been suggested as a potential means whereby atmospheric emissions of greenhouse gases may be reduced. However, our knowledge of the geohydrology, geochemistry, geophysics, and geomechanics of CO{sub 2} disposal must be refined if this technology is to be implemented safely, efficiently, and predictably. As a prelude to a fully coupled treatment of physical and chemical effects of CO{sub 2} injection, we have analyzed the impact of CO{sub 2} immobilization through carbonate precipitation. A survey of all major classes of rock-forming minerals, whose alteration would lead to carbonate precipitation, indicated that very few minerals are present in sufficient quantities in aquifer host rocks to permit significant sequestration of CO{sub 2}. We performed batch reaction modeling of the geochemical evolution of three different aquifer mineralogies in the presence of CO{sub 2} at high pressure. Our modeling considered (1) redox processes that could be important in deep subsurface environments, (2) the presence of organic matter, (3) the kinetics of chemical interactions between the host rock minerals and the aqueous phase, and (4) CO{sub 2} solubility dependence on pressure, temperature and salinity of the system. The geochemical evolution under both natural background and CO{sub 2} injection conditions was evaluated. In addition, changes in porosity were monitored during the simulations. Results indicate that CO{sub 2} sequestration by matrix minerals varies considerably with rock type. Under favorable conditions the amount of CO{sub 2} that may be sequestered by precipitation of secondary carbonates is comparable with and can be larger than the effect of CO{sub 2} dissolution in pore waters. The precipitation of ankerite and siderite is sensitive to the rate of reduction of ferric mineral precursors such as glauconite, which in turn is dependent on the reactivity of associated organic material. The accumulation of carbonates in the rock matrix ...
Date: July 20, 2001
Creator: Xu, Tianfu; Apps, John A. & Pruess, Karsten
Partner: UNT Libraries Government Documents Department

Chemical structure and dynamics. Annual report 1995

Description: The Chemical Structure and Dynamics program is a major component of Pacific Northwest National Laboratory`s Environmental Molecular Sciences Laboratory (EMSL), providing a state-of-the-art collaborative facility for studies of chemical structure and dynamics. We respond to the need for a fundamental, molecular-level understanding of chemistry at a wide variety of environmentally important interfaces by (1) extending the experimental characterization and theoretical description of chemical reactions to encompass the effects of condensed media and interfaces; (2) developing a multidisciplinary capability for describing interfacial chemical processes within which the new knowledge generated can be brought to bear on complex phenomena in environmental chemistry and in nuclear waste processing and storage; and (3) developing state-of-the-art analytical methods for the characterization of waste tanks and pollutant distributions, and for detection and monitoring of trace atmospheric species.
Date: May 1996
Creator: Colson, S. D. & McDowell, R. S.
Partner: UNT Libraries Government Documents Department