WorldWideScience

Sample records for calcined aggregates

  1. The Effect of Calcination Temperature on the Performance of TiO2 Aggregates-based Dye Solar Cells (DSCs)

    International Nuclear Information System (INIS)

    In this paper, the effect of calcination temperature on the physicochemical properties of synthesized TiO2 aggregates and their influence on overall light conversion efficiency of dye solar cell (DSc) were investigated. Samples of TiO2 aggregates (mean size of 0.45 μm) composing of nano crystallites (10-40 nm) were synthesized through hydrolysis of dilute titanium alkoxide in ethanol. Phase and microstructure of the TiO2 obtained have been characterized using FESEM, XRD and UV-Vis spectroscopy. I-V characterization shows that TiO2 aggregates based DSC demonstrated better performance compared to nanoparticles (P-25)-based DSC. The optimum calcination temperature was found to be about 500 degree Celsius with efficiency of 4.456 %, which is 30 % increment compared to P-25-based DSC under the same condition. (author)

  2. Injector for calciner

    Energy Technology Data Exchange (ETDEWEB)

    Davis, R.L.; Edwards, D.L.; Graf, H.G.; Macbeth, W.B. Jr.

    1983-10-04

    Combustion gas such as air, oxygen-enriched air or oxygen is introduced to a calcining zone at an intermediate level in a vertical shaft kiln for the calcining of petroleum coke utilizing a plurality of radially disposed combustion gas injectors and at least one vertically disposed injector located within the shaft kiln and extending into the calcining zone. The injector includes means for circulating coolant around the periphery of the injector so that common metals may be used in the high temperature (above 2000/sup 0/ F.) environment of the shaft kiln. The vertical combustion gas injector may extend from the top of the calcining chamber to the calcining zone or from the bottom of the calcining chamber to the calcining zone. When the vertical combustion gas injector extends vertically upwardly from the bottom of the calcining chamber, means for introducing recycle gas to the calcining chamber may be incorporated into the vertical combustion gas injector.

  3. Calcine production and management

    International Nuclear Information System (INIS)

    The process technology related to calcination of power reactor wastes is summarized. The primary calcination processes developed are spray calcination, fluidized-bed calcination, and rotary kiln calcination. Calcines from the spray calciner and rotary kiln are fed directly to a glassification process. The fluidized-bed product can either be fed to a waste form conversion process or stored. The major process steps for calcinations are feed preparation, calcination and product handling, and off-gas cleanup. Feed systems for the three processes are basically similar. Gravity flow and pump pressurized systems have been used successfully. The major problems are fatigue failure of feed valve bellows, plugging by undissolved solids, and calibration of flowmeters. Process heat input is by electrical resistance heating for the spray and rotary kiln calciners and in-bed combustion or in-bed heat exchange for the fluidized-bed system. Low-melting solids which can cause scaling or solids agglomeration in any of the processes is a major calcination problem; however, feed blending, process operating conditions, and equipment design have successfully controlled solids agglomeration. Primary off-gas cleanup devices for particulates are cyclones, sintered metal filters, venturi scrubbers, and HEPA filters. Scrubbers, condensers, and solid adsorbents are used successfully for volatile ruthenium removal. The years of pilot-plant and plant-scale calcination testing and operation of the three systems have shown that reactor wastes can be calcined safely and practically. 11 figures, 2 tables

  4. Desempenho mecânico de misturas asfálticas confeccionadas com agregados sintéticos de argila calcinada Mechanical performance of asphalt mixtures composed of synthetic calcinated clay aggregates

    Directory of Open Access Journals (Sweden)

    C. A. Frota

    2007-09-01

    .A substantial number of municipal districts in the State of Amazonas are located in areas which are poor in stony materials. And this has led pavement builders into adopting alternatives which have historically produced pavements with low mechanical strength. Whist more effective and appropriate from a technical standpoint, the asphalt concrete has been usually left aside due to the referred lack of stony materials. Because of the specific situation in the State of Amazonas the adoption of synthetic calcinated clay aggregates (SCCA, with an abundant raw material (clay in the State of Amazonas is recommended in lieu of the traditional practice. Previous works carried out by the Federal University of Amazonas Geotechny Group have demonstrated that the clay soil commonly used in the production of ceramic materials can yield synthetic aggregates with adequate mechanical properties. In this research work, samples featuring similar characteristics as those of the soils in question have been found along the BR-319 highway connecting the Manaus (AM city to Porto Velho (RO city. The transportation structure in general is in deplorable conditions. Justifiably so, the recovery of this highway has been earmarked as one of the targets for the Ministry of Transportation. In this study, asphalt mixtures were blended with synthetic aggregates and pebbles taken from the river bed in order to compare the mechanical performance of such mixtures by means of the determination of the resilient modulus (RM. The results, as a rule, have shown that the asphalt mixtures comprising synthetic calcinated clay aggregates when compared with those comprising the naturally-found material (river bed pebbles have shown: (a greater tensile and resilient modulus strengths; (b low deformation tendency, as well as a considerable elastic recovery and (c less susceptibility to permanent deformation.

  5. Dissolution Kinetics of Alumina Calcine

    Energy Technology Data Exchange (ETDEWEB)

    Batcheller, Thomas Aquinas

    2001-09-01

    Dissolution kinetics of alumina type non-radioactive calcine was investigated as part of ongoing research that addresses permanent disposal of Idaho High Level Waste (HLW). Calcine waste was produced from the processing of nuclear fuel at the Idaho Nuclear Technology and Engineering Center (INTEC). Acidic radioactive raffinates were solidified at ~500°C in a fluidized bed reactor to form the dry granular calcine material. Several Waste Management alternatives for the calcine are presented in the Idaho High Level Waste Draft EIS. The Separations Alternative addresses the processing of the calcine so that the HLW is ready for removal to a national geological repository by the year 2035. Calcine dissolution is the key front-end unit operation for the separations alternative.

  6. Calcination/dissolution residue treatment

    International Nuclear Information System (INIS)

    Currently, high-level wastes are stored underground in steel-lined tanks at the Hanford site. Current plans call for the chemical pretreatment of these wastes before their immobilization in stable glass waste forms. One candidate pretreatment approach, calcination/dissolution, performs an alkaline fusion of the waste and creates a high-level/low-level partition based on the aqueous solubilities of the components of the product calcine. Literature and laboratory studies were conducted with the goal of finding a residue treatment technology that would decrease the quantity of high-level waste glass required following calcination/dissolution waste processing. Four elements, Fe, Ni, Bi, and U, postulated to be present in the high-level residue fraction were identified as being key to the quantity of high-level glass formed. Laboratory tests of the candidate technologies with simulant high-level residues showed reductive roasting followed by carbonyl volatilization to be successful in removing Fe, Ni, and Bi. Subsequent bench-scale tests on residues from calcination/dissolution processing of genuine Hanford Site tank waste showed Fe was separated with radioelement decontamination factors of 70 to 1,000 times with respect to total alpha activity. Thermodynamic analyses of the calcination of five typical Hanford Site tank waste compositions also were performed. The analyses showed sodium hydroxide to be the sole molten component in the waste calcine and emphasized the requirement for waste blending if fluid calcines are to be achieved. Other calcine phases identified in the thermodynamic analysis indicate the significant thermal reconstitution accomplished in calcination

  7. Utilização de massas cerâmicas na produção de agregado sintético de argila calcinada para uso em concreto Use of ceramic bodies in the production of synthetic aggregate calcined clay for use in concrete

    Directory of Open Access Journals (Sweden)

    E. M. Cabral

    2008-12-01

    manufacturing synthetic aggregate of calcined clay for use in concrete. The ceramic pastes were analyzed by X-ray diffraction, evaluation of chemical composition, particle size distribution and plasticity. The samples were prepared by uniaxial pressing at 20 MPa and calcined at 850, 950, 1050 and 1150 ºC. The technological properties evaluated were: linear shrinkage, water absorption, apparent specific mass and vitrification temperature. The ceramic paste that presented the smallest apparent specific mass and smallest percentile of molding humidity was chosen for synthetic aggregate. The results obtained for the concrete produced with the synthetic aggregate of calcined clay show its potential as a substitute of the natural aggregate of the Amazonic region, the natural gravel.

  8. Alternative calcination development status report

    International Nuclear Information System (INIS)

    The Programmatic Spent Nuclear Fuel and (INEEL) Environmental Restoration and Waste Management Programs Environmental Impact Statement Record of Decision, dated June 1, 1995, specifies that high-level waste stored in the underground tanks at the ICPP continue to be calcined while other options to treat the waste are studied. Therefore, the High-Level Waste Program has funded a program to develop new flowsheets to increase the liquid waste processing rate. Simultaneously, a radionuclide separation process, as well as other options, are also being developed, which will be compared to the calcination treatment option. Two alternatives emerged as viable candidates; (1) elevated temperature calcination (also referred to as high temperature calcination), and (2) sugar-additive calcination. Both alternatives were determined to be viable through testing performed in a lab-scale calcination mockup. Subsequently, 10-cm Calciner Pilot Plant scoping tests were successfully completed for both flowsheets. The results were compared to the standard 500 C, high-ANN flow sheet (baseline flowsheet). The product and effluent streams were characterized to help elucidate the process chemistry and to investigate potential environmental permitting issues. Several supplementary tests were conducted to gain a better understanding of fine-particles generation, calcine hydration, scrub foaming, feed makeup procedures, sugar/organic elimination, and safety-related issues. Many of the experiments are only considered to be scoping tests, and follow-up experiments will be required to establish a more definitive understanding of the flowsheets. However, the combined results support the general conclusion that flowsheet improvements for the NWCF are technically viable

  9. Simultaneous chlorination and sulphation of calcined limestone

    Energy Technology Data Exchange (ETDEWEB)

    Matsukata, M.; Takeda, K.; Miyatain, T.; Ueyama, K. [Osaka University, Osaka (Japan). Dept. of Chemical Engineering

    1996-06-01

    In order to analyze HCl and SO{sub 2} retention in fluidized bed combustors of coal and wastes, chlorination and sulphation of calcined limestone were investigated at 1023 K and atmospheric pressure using thermogravimetry. The rate of chlorination of calcined limestone slightly depended on its particle size and was kept almost constant against the progress of chlorination. In contrast, the rate of sulphation increased with decreasing particle size and steeply decreased with the progress of sulphation as commonly reported. It was found that the sulphation was markedly accelerated in the presence of HCl. Such acceleration of sulphation was remarkable for larger limestone. The level of conversion of CaO to (CaSO{sub 4} + CaCl{sub 2}) always approached 100% in the simultaneous absorption of HCl and SO{sub 2}. It was observed by SEM that in the chlorination a number of spherical aggregates and large voids were formed on the surface of limestone and that large aggregates with very flat surface and large voids have been formed in the course of the simultaneous chlorination and sulphation. The chlorination behavior and the acceleration of SO{sub 2} absorption in the presence of HCl can be due both to the formation of a mobile Cl{sup -} ion-containing phase and to the formation of voids playing a role of the diffusion paths for HCl and SO{sub 2} toward the interior of a limestone particle. Melting of a eutectic mixture of CaCl{sub 2} and CaSO{sub 4} might largely contribute to the promotion of SO{sub 2} absorption in the case of simultaneous absorption of HCl and SO{sub 2}. 8 refs., 4 figs.

  10. Dissolution properties of calcined gangue

    Institute of Scientific and Technical Information of China (English)

    Huajian Li; Henghu Sun; Xuchu Tie; Xuejun Xiao

    2006-01-01

    To study the dissolution mechanism of gangue, dissolution characteristics of the gangue samples calcined at different temperatures in alkaline solutions and alkali metal silicate solutions with respect to Si and A1 ions were analyzed by identical coupled plasma optical emission spectroscopy (ICP). The results show that the extent of dissolution of A1 and Si varies with calcination temperature. It shows that the samples have a higher degree of dissolution in NaOH than in KOH medium. Si and A1 appear to have synchro-dissolution behavior in alkaline solution, which means that Si and A1 could dissolve from the mineral surface in certain linked forms. The result that a higher degree of dissolution exists in sodium silicate solution and a lower degree of dissolution exists in sodium-potassium silicate solution of A1 is proved by the 29Si NMR spectra and the mean connectivity degree of these alkali metal silicate solutions.

  11. Summary of Waste Calcination at INTEC

    Energy Technology Data Exchange (ETDEWEB)

    O' Brien, Barry Henry; Newby, Bill Joe

    2000-10-01

    Fluidized-bed calcination at the Idaho Nuclear Technologies and Engineering Center (INTEC, formally called the Idaho Chemical Processing Plant) has been used to solidify acidic metal nitrate fuel reprocessing and incidental wastes wastes since 1961. A summary of waste calcination in full-scale and pilot plant calciners has been compiled for future reference. It contains feed compositions and operating conditions for all the processing campaigns for the original Waste Calcining Facility (WCF), the New Waste Calcining Facility (NWCF) started up in 1982, and numerous small scale pilot plant tests for various feed types. This summary provides a historical record of calcination at INTEC, and will be useful for evaluating calcinability of future wastes.

  12. Cementitious artificial aggregate particles for high-skid resistance pavements

    OpenAIRE

    De Larrard, François; MARTINEZ CASTILLO, Rafael; Sedran, Thierry; HAUZA, Philippe; Poirier, Jean Eric

    2012-01-01

    For some critical road sections, a high skid resistance of wearing course is required to minimise the risk of traffic accidents. Nowadays this skid resistance is mainly brought by the use of special aggregates as calcined bauxite, a scarce and expensive material. The paper presents a patented technology, where a special high-performance mortar is produced and crushed at early age. These cementitious artificial aggregates (CAA) can display aggregate properties close to those of calcined bauxit...

  13. Effect of Calcination on the Sintering of Gel-Derived, Zirconia-Toughened Alumina

    OpenAIRE

    Exter, den, P.; Winnubst, Louis; Leuwerink, Theo H.P.; Burggraaf, Anthonie J.

    1994-01-01

    The densification behavior of ZrO2 (+ 3 mol% Y2O3)/85 wt% Al2O3 powder compacts, prepared by the hydrolysis of metal chlorides, can be characterized by a transition- and an α-alumina densification stage. The sintering behavior is strongly determined by the densification of the transition alumina aggregates. Intra-aggregate porosity, resulting from calcination at 800°C, partly persists during sintering and alumina phase transformation and negatively influences further macroscopic densification...

  14. Estimation of alkali metal mole percent and weight of calcined solids for ICPP calcine

    International Nuclear Information System (INIS)

    An updated method is given for estimation of the weight of calcined solids and volume reduction factor for calcine, and mole percent sodium plus potassium in calcine produced from radioactive waste in a fluidized-bed calciner at the Idaho Chemical Processing Plant (ICPP). It incorporates new information on a calcine chemistry from a study by K. N. Brewer and G. F. Kessinger in which they determined the compounds formed during calcination by both high temperature thermodynamic equilibrium calculations and by analyses of pilot-plant calcines. An explanation of the assumptions made in the calculations, along with several example calculations and comparisons with the previous calculation methods are included. This method allows calculation of the heat generation rate and sodium content of the calcine, which are used to determine the suitability of the calcine for storage in the ICPP bin sets. Although this method accurately predicts the weight of calcine and mole percent Na + K for its intended purpose, the compounds predicted should only be used as a first approximation for other purposes since the calculation does not incorporate all of the compounds, such as mixed-metal oxides, which may form during calcination

  15. XANES analysis of dried and calcined bones

    Energy Technology Data Exchange (ETDEWEB)

    Rajendran, Jayapradhi [Materials Science and Engineering Department, University of Texas at Arlington (United States); Gialanella, Stefano [Materials Science and Industrial Technology Department, University of Trento (Italy); Aswath, Pranesh B., E-mail: aswath@uta.edu [Materials Science and Engineering Department, University of Texas at Arlington (United States)

    2013-10-15

    The structure of dried and calcined bones from chicken, bovine, deer, pig, sheep and chamois was examined using X-ray Absorption Near Edge Structure (XANES) spectroscopy. The oxygen K-edge absorption edge indicates that the surface of dried bone has a larger proportion of carbonate than the interior that is made up of phosphates. The phosphorus L and K edge clearly indicate that pyrophosphates, α-tricalcium phosphate (α-TCP) and hydrogen phosphates of Ca do not exist in either the dried bone or calcined bone and phosphorus exists as either β-tricalcium phosphate (β-TCP) or hydroxyapatite, both in the dried and calcined conditions. The Ca K-edge analysis indicates that β-TCP is the likely form of phosphate in both the dried and calcined conditions. - Highlights: • For the first time bones of five different species of vertebrates have been compared in both the dried and calcined states. • O, P and Ca edges detail the local coordination of these atoms in dried and calcined bone. • O K-edge shows that the surface of bone has more CO{sub 3} while the interior has more PO{sub 4}. • P and Ca edges eliminate the presence of pyrophosphates and confirmed the presence of HA and β-TCP. • The stability of these phosphates on calcination has been examined using XANES.

  16. Radiant-Heat Spray Calcination Studies

    International Nuclear Information System (INIS)

    The radiant-heat spray calcination process for conversion of liquid wastes to solids is described and the design of a one-gallon-per-hour spray calcination unit coupled with a small melt pot, capable of being run separately as a pot calciner, is discussed. The units were designed to test the feasibility of the calcination process with actual Purex plant waste in terms of the process as a unit operation, off-gas treatment, fission-product behaviour, condensate and calcined waste characteristics. The entire system was made to fit into an available 7-1/2 ft x 15 ft x 15 ft tall, manipulator-equipped, shielded cell which is also described. Included in the design discussion are: the resistance heating of the spray calciner column, thermal insulation of the column, spray nozzle, method of nozzle replacement, induction heating of the melt pot, radioactivity scanner for the pot, off-gas processing system including condenser, scrubber and filters, off-gas sampling device, liquid sampling device, wash-down system, feed system, instrumentation and control methods. The experience gained in operating the calciners and associated equipment is discussed. Experimental results presented show the effectiveness of off-gas decontamination and behaviour of gross chemical constituents and some specific fission products. (author)

  17. XANES analysis of dried and calcined bones

    International Nuclear Information System (INIS)

    The structure of dried and calcined bones from chicken, bovine, deer, pig, sheep and chamois was examined using X-ray Absorption Near Edge Structure (XANES) spectroscopy. The oxygen K-edge absorption edge indicates that the surface of dried bone has a larger proportion of carbonate than the interior that is made up of phosphates. The phosphorus L and K edge clearly indicate that pyrophosphates, α-tricalcium phosphate (α-TCP) and hydrogen phosphates of Ca do not exist in either the dried bone or calcined bone and phosphorus exists as either β-tricalcium phosphate (β-TCP) or hydroxyapatite, both in the dried and calcined conditions. The Ca K-edge analysis indicates that β-TCP is the likely form of phosphate in both the dried and calcined conditions. - Highlights: • For the first time bones of five different species of vertebrates have been compared in both the dried and calcined states. • O, P and Ca edges detail the local coordination of these atoms in dried and calcined bone. • O K-edge shows that the surface of bone has more CO3 while the interior has more PO4. • P and Ca edges eliminate the presence of pyrophosphates and confirmed the presence of HA and β-TCP. • The stability of these phosphates on calcination has been examined using XANES

  18. Calcined solids storage facility closure study

    Energy Technology Data Exchange (ETDEWEB)

    Dahlmeir, M.M.; Tuott, L.C.; Spaulding, B.C. [and others

    1998-02-01

    The disposal of radioactive wastes now stored at the Idaho National Engineering and Environmental Laboratory is currently mandated under a {open_quotes}Settlement Agreement{close_quotes} (or {open_quotes}Batt Agreement{close_quotes}) between the Department of Energy and the State of Idaho. Under this agreement, all high-level waste must be treated as necessary to meet the disposal criteria and disposed of or made road ready to ship from the INEEL by 2035. In order to comply with this agreement, all calcined waste produced in the New Waste Calcining Facility and stored in the Calcined Solids Facility must be treated and disposed of by 2035. Several treatment options for the calcined waste have been studied in support of the High-Level Waste Environmental Impact Statement. Two treatment methods studied, referred to as the TRU Waste Separations Options, involve the separation of the high-level waste (calcine) into TRU waste and low-level waste (Class A or Class C). Following treatment, the TRU waste would be sent to the Waste Isolation Pilot Plant (WIPP) for final storage. It has been proposed that the low-level waste be disposed of in the Tank Farm Facility and/or the Calcined Solids Storage Facility following Resource Conservation and Recovery Act closure. In order to use the seven Bin Sets making up the Calcined Solids Storage Facility as a low-level waste landfill, the facility must first be closed to Resource Conservation and Recovery Act (RCRA) standards. This study identifies and discusses two basic methods available to close the Calcined Solids Storage Facility under the RCRA - Risk-Based Clean Closure and Closure to Landfill Standards. In addition to the closure methods, the regulatory requirements and issues associated with turning the Calcined Solids Storage Facility into an NRC low-level waste landfill or filling the bin voids with clean grout are discussed.

  19. Calcined solids storage facility closure study

    International Nuclear Information System (INIS)

    The disposal of radioactive wastes now stored at the Idaho National Engineering and Environmental Laboratory is currently mandated under a open-quotes Settlement Agreementclose quotes (or open-quotes Batt Agreementclose quotes) between the Department of Energy and the State of Idaho. Under this agreement, all high-level waste must be treated as necessary to meet the disposal criteria and disposed of or made road ready to ship from the INEEL by 2035. In order to comply with this agreement, all calcined waste produced in the New Waste Calcining Facility and stored in the Calcined Solids Facility must be treated and disposed of by 2035. Several treatment options for the calcined waste have been studied in support of the High-Level Waste Environmental Impact Statement. Two treatment methods studied, referred to as the TRU Waste Separations Options, involve the separation of the high-level waste (calcine) into TRU waste and low-level waste (Class A or Class C). Following treatment, the TRU waste would be sent to the Waste Isolation Pilot Plant (WIPP) for final storage. It has been proposed that the low-level waste be disposed of in the Tank Farm Facility and/or the Calcined Solids Storage Facility following Resource Conservation and Recovery Act closure. In order to use the seven Bin Sets making up the Calcined Solids Storage Facility as a low-level waste landfill, the facility must first be closed to Resource Conservation and Recovery Act (RCRA) standards. This study identifies and discusses two basic methods available to close the Calcined Solids Storage Facility under the RCRA - Risk-Based Clean Closure and Closure to Landfill Standards. In addition to the closure methods, the regulatory requirements and issues associated with turning the Calcined Solids Storage Facility into an NRC low-level waste landfill or filling the bin voids with clean grout are discussed

  20. Activity and Structure of Calcined Coal Gangue

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Coal gangue was activated by means of calcination in seven temperature ranges. Systematic research was made about activation mechanism and structural evolution. Glycerin-ethanol method, SEM, MIP and XRD were used to determine the variation of structure and activation of coal gangue during the calcination.The experimental results show that because of heat treatment in the range of calcination temperature, mineral composition and microstructure of coal gangue are changed. In addition, its activity is improved evidently. The amount of lime absorbed by the sample calcined at 700 C is 2-4 times that by uncalcined coal gangue in the course of hydration. When NaOH is added to coal gangue-lime system, hydration reaction of the system is sped up and the microstructure of hydrating samples of coal gangue is improved.

  1. Activity and structure of calcined coal gangue

    Energy Technology Data Exchange (ETDEWEB)

    Gong Chenchen; Li Dongxu; Wang Xiaojun; Li Zongjin [Nanjing University of Technology, Nanjing (China). College of Materials Science and Engineering

    2007-12-15

    Coal gangue was activated by means of calcination in seven temperature ranges. Systematic research was made about activation mechanism and structural evolution. The glycerin-ethanol method, SEM, MIP and XRD were used to determine the variation of structure and activation of coal gangue during calcination. The experimental results show that because of heat treatment in the range of calcination temperatures, mineral composition and microstructure of coal gangue are changed. In addition, its activity is improved. The amount of lime absorbed by the sample calcined at 700{sup o}C is 2-4 times that by uncalcined coal gangue in the course of hydration. When NaOH is added to coal gangue-lime system, the hydration reaction rate of the system is increased and the microstructure of hydrating samples of coal gangue is improved.

  2. Bin Set 1 Calcine Retrieval Feasibility Study

    International Nuclear Information System (INIS)

    At the Department of Energy's Idaho Nuclear Technology and Engineering Center, as an interim waste management measure, both mixed high-level liquid waste and sodium bearing waste have been solidified by a calculation process and are stored in the Calcine Solids Storage Facilities. This calcined product will eventually be treated to allow final disposal in a national geologic repository. The Calcine Solids Storage Facilities comprise seven ''bit sets.'' Bin Set 1, the first to be constructed, was completed in 1959, and has been in service since 1963. It is the only bin set that does not meet current safe-shutdown earthquake seismic criteria. In addition, it is the only bin set that lacks built-in features to aid in calcine retrieval. One option to alleviate the seismic compliance issue is to transport the calcine from Bin Set 1 to another bin set which has the required capacity and which is seismically qualified. This report studies the feasibility of retrieving the calcine from Bi n Set 1 and transporting it into Bin Set 6 which is located approximately 650 feet away. Because Bin Set 1 was not designed for calcine retrieval, and because of the high radiation levels and potential contamination spread from the calcined material, this is a challenging engineering task. This report presents preconceptual design studies for remotely-operated, low-density, pneumatic vacuum retrieval and transport systems and equipment that are based on past work performed by the Raytheon Engineers and Constructors architectural engineering firm. The designs presented are considered feasible; however, future development work will be needed in several areas during the subsequent conceptual design phase

  3. Bin Set 1 Calcine Retrieval Feasibility Study

    Energy Technology Data Exchange (ETDEWEB)

    R. D. Adams; S. M. Berry; K. J. Galloway; T. A. Langenwalter; D. A. Lopez; C. M. Noakes; H. K. Peterson; M. I. Pope; R. J. Turk

    1999-10-01

    At the Department of Energy's Idaho Nuclear Technology and Engineering Center, as an interim waste management measure, both mixed high-level liquid waste and sodium bearing waste have been solidified by a calculation process and are stored in the Calcine Solids Storage Facilities. This calcined product will eventually be treated to allow final disposal in a national geologic repository. The Calcine Solids Storage Facilities comprise seven ''bit sets.'' Bin Set 1, the first to be constructed, was completed in 1959, and has been in service since 1963. It is the only bin set that does not meet current safe-shutdown earthquake seismic criteria. In addition, it is the only bin set that lacks built-in features to aid in calcine retrieval. One option to alleviate the seismic compliance issue is to transport the calcine from Bin Set 1 to another bin set which has the required capacity and which is seismically qualified. This report studies the feasibility of retrieving the calcine from Bi n Set 1 and transporting it into Bin Set 6 which is located approximately 650 feet away. Because Bin Set 1 was not designed for calcine retrieval, and because of the high radiation levels and potential contamination spread from the calcined material, this is a challenging engineering task. This report presents preconceptual design studies for remotely-operated, low-density, pneumatic vacuum retrieval and transport systems and equipment that are based on past work performed by the Raytheon Engineers and Constructors architectural engineering firm. The designs presented are considered feasible; however, future development work will be needed in several areas during the subsequent conceptual design phase.

  4. Calcined silica for enhanced polyethylene nano composites

    OpenAIRE

    Praeger, M.; Hosier, I.L.; A. S. Vaughan; Swingler, S.G.

    2015-01-01

    In this paper the dielectric performance of polymer composites containing untreated silica nanoparticles is compared with those containing calcined nanosilica. Nanosilica (as delivered by the supplier) is calcined at 1050 ºC for 10 h under an atmosphere of dry nitrogen. Efficacy of treatment is confirmed by Fourier transform Infrared spectroscopy (FTIR) and thermogravimetric analysis (TGA); the measurements being consistent with a marked reduction in both surface adsorbed water and in the num...

  5. Experimental results: Pilot plant calcine dissolution and liquid feed stability

    International Nuclear Information System (INIS)

    The dissolution of simulated Idaho Chemical Processing Plant pilot plant calcines, containing none of the radioactive actinides, lanthanides or fission products, was examined to evaluate the solubility of calcine matrix materials in acidic media. This study was a necessary precursor to dissolution and optimization experiments with actual radionuclide-containing calcines. The importance of temperature, nitric acid concentration, ratio of acid volume to calcine mass, and time on the amount, as a weight percentage of calcine dissolved, was evaluated. These parameters were studied for several representative pilot plant calcine types: (1) Run No. 74 Zirconia calcine; (2) Run No. 17 Zirconia/Sodium calcine; (3) Run No. 64 Zirconia/Sodium calcine; (3) Run No. 1027 Alumina calcine; and (4) Run No. 20 Alumina/Zirconia/Sodium calcine. Statistically designed experiments with the different pilot plant calcines indicated the effect of the studied process variables on the amount of calcine dissolved decreases in the order: Acid/Calcine Ratio > Temperature > HNO3 Concentration > Dissolution Time. The following conditions are suitable to achieve greater than 90 wt. % dissolution of most Zr, Al, or Na blend calcines: (1) Maximum nitric acid concentration of 5M; (2) Minimum acid/calcine ratio of 10 mL acid/1 gram calcine; (3) Minimum dissolution temperature of 90 degrees C; and (4) Minimum dissolution time of 30 minutes. The formation of calcium sulphate (CaSO4) precipitates was observed in certain dissolved calcine solutions during the dissolution experiments. Consequently, a study was initiated to evaluate if and under what conditions the resulting dissolved calcine solutions would be unstable with regards to precipitate formation. The results indicate that precipitate formation in the calcine solutions prepared under the above proposed dissolution conditions are not anticipated

  6. 1st International Conference on Calcined Clays for Sustainable Concrete

    CERN Document Server

    Favier, Aurélie

    2015-01-01

    This volume focuses on research and practical issues linked to Calcined Clays for Sustainable Concrete. The main subjects are geology of clays, hydration and performance of blended systems with calcined clays, alkali activated binders, economic and environmental impacts of the use of calcined clays in cement based materials. Topics addressed in this book include the influence of processing on reactivity of calcined clays, influence of clay mineralogy on reactivity, geology of clay deposits, Portland-calcined clay systems, hydration, durability, performance, Portland-calcined clay-limestone systems, hydration, durability, performance, calcined clay-alkali systems, life cycle analysis, economics and environmental impact of use of calcined clays in cement and concrete, and field applications. This book compiles the different contributions of the 1st International Conference on Calcined Clays for Sustainable Concrete, which took place in Lausanne, Switzerland, June, 23-25, 2015.The papers present the latest  res...

  7. Calcine Conversion Facility alternative concepts engineering studies

    International Nuclear Information System (INIS)

    The purpose of the engineering study reported is to develop conceptual designs for two alternative facilities for the conversion of high level waste calcine to high level glass. The objectives and design bases of the two concepts (CCF/RSSF and CCF/FRP) are described. No recommendation of one concept in preference to the other is given. (LK)

  8. Reaction between Hydrogen Sulfide and Limestone Calcines

    Czech Academy of Sciences Publication Activity Database

    Hartman, Miloslav; Svoboda, Karel; Trnka, Otakar; Čermák, Jiří

    2002-01-01

    Roč. 41, č. 10 (2002), s. 2392-2398. ISSN 0888-5885 R&D Projects: GA AV ČR IAA4072711; GA AV ČR IAA4072801 Keywords : hydrogen sulfide * limestone calcines * desulfurization Subject RIV: CI - Industrial Chemistry, Chemical Engineering Impact factor: 1.247, year: 2002

  9. JUDGMENT AGGREGATION AND PREFERENCE AGGREGATION

    OpenAIRE

    Joanna Ochremiak

    2011-01-01

    In the paper we present an introduction to the theory of judgment aggregation and discuss its relation to the theory of preference aggregation. We compare the formal model of judgment aggregation, based on logic, with the formal model of preference aggregation. Finally, we present a theorem in judgmentaggregation which is an exact analogue of Arrow's theorem for strict preferences.

  10. Modeling and Simulation of Petroleum Coke Calcination in Pot Calciner Using Two-Fluid Model

    Science.gov (United States)

    Xiao, Jin; Huang, Jindi; Zhong, Qifan; Zhang, Hongliang; Li, Jie

    2016-02-01

    The aim of this work was to establish a mathematical model for the analysis of calcining process of petroleum coke in a 24-pot calciner via computational fluid dynamics (CFD) numerical simulation method. The model can be divided into two main parts (1) heterogeneous reacting flow of petroleum coke calcination in the pot was simulated using a two-fluid model approach where the gas and solid phase are treated as a continuous phases; and (2) the standard turbulence equations combined with the finite rate/eddy-dissipation combustion model and discrete ordinates model were solved for the turbulent gas reacting flow in the flue. The model of the calcining process was implemented in ANSYS Fluent 15.0 (commercial CFD software) and validated by industrial production data. After the validation research, the model has been applied to inspect the distribution features of the temperature field in the furnace, the concentration field of residual moisture and volatiles in the petroleum coke, and the vector velocity field of gas and solid phases. This research can provide a theoretical basis for optimizing the structure and improving the automatic control level of a pot calciner.

  11. Experimental and modeling study of flash calcination of kaolinite rich clay particles in a gas suspension calciner

    DEFF Research Database (Denmark)

    Gebremariam, Abraham Teklay; Yin, Chungen; Rosendahl, Lasse;

    2015-01-01

    gas suspension calciner, with the aim to derive useful guidelines on smart calcination for obtaining products of the best pozzolanic properties. Calcination tests are performed in the calciner under six different operation conditions. The raw feed and the calcined clay samples are all characterized...... experimentally and a mathematical model is also developed to predict the conversion of the clay particles. The model properly accounts for the particle–ambient flow interaction and numerically solves all the processes occurring within the clay particles. The model predictions are compared against the...

  12. Effects of Calcination and Milling Process Conditions for Ceria Slurry on Shallow-Trench-Isolation Chemical-Mechanical Polishing Performance

    Science.gov (United States)

    Kim, Jun-Seok; Kang, Hyun-Goo; Kanemoto, Manabu; Paik, Ungyu; Park, Jea-Gun

    2007-12-01

    To improve the performance of shallow trench isolation chemical-mechanical polishing (STI-CMP) in terms of the removal selectivity of oxide and nitride films and the formation of surface defects, we investigated the effects of the calcination and milling process conditions during ceria slurry synthesis. We have focused on the effects of particle size distribution, the large-particle size, and the dispersion stability in a ceria slurry. We determined the optimum bead size for milling and appropriate calcination temperatures in order to obtain a reasonable particle distribution, with lower numbers of fine primary particles and large, agglomerated particles, in ceria slurry. This was achieved by reducing the quantity of aggregated particles during milling and two-step calcination process generating higher-density particles. These results can be qualitatively explained by abrasive collisions occurring between the milling beads and the decarbonation of cerium carbonate through diffusion during the manufacturing process used for the ceria slurry.

  13. Countercurrent flowsheet testing of the TRUEX process with ICPP calcine

    Energy Technology Data Exchange (ETDEWEB)

    Law, J.D.; Herbst, R.S.; Brewer, K.N.; Todd, T.A.

    1998-07-01

    Calcine was generated at the Idaho Chemical Processing Plant over several decades as a method of solidifying numerous raffinates and wastes from spent nuclear fuel reprocessing for convenient interim storage. Unfortunately, the bulk of the calcine is inert, with radionuclides comprising less than 1 weight percent of the total calcine mass. The bulk of the calcine currently stored at the ICPP was produced from wastes generated during reprocessing of zirconium clad fuels. Consequently, this material contains varying, but large quantities of zirconium oxide. Currently, separations options are being considered for acidic solutions of dissolved ICPP calcines to minimize high level waste volumes and economic penalties perceived for final disposal of these wastes. The actinide separation process being emphasized for the dissolved calcine solutions is the TRUEX process. Substantial problems have been encountered during TRUEX flowsheet development efforts for dissolved zirconium calcine simulant due to the high concentrations and subsequent extraction of zirconium from the feed. Alteration of the calcine dissolution parameters has resulted in the development of a successful TRUEX/Zr calcine baseline flowsheet. This flowsheet has been tested using 22 stages of a 2.0 centimeter diameter centrifugal contactor pilot plant using simulated dissolved Zr calcine solution. With this flowsheet, a removal efficiency of > 96% was obtained for {sup 241}Am (analytical detection limits were reached). Less than 0.25% of the {sup 95}Zr exited with the high-level waste strip product.

  14. Waste Calcining Facility remote inspection report

    International Nuclear Information System (INIS)

    The purpose of the Waste Calcining Facility (WCF) remote inspections was to evaluate areas in the facility which are difficult to access due to high radiation fields. The areas inspected were the ventilation exhaust duct, waste hold cell, adsorber manifold cell, off-gas cell, calciner cell and calciner vessel. The WCF solidified acidic, high-level mixed waste generated during nuclear fuel reprocessing. Solidification was accomplished through high temperature oxidation and evaporation. Since its shutdown in 1981, the WCFs vessels, piping systems, pumps, off-gas blowers and process cells have remained contaminated. Access to the below-grade areas is limited due to contamination and high radiation fields. Each inspection technique was tested with a mock-up in a radiologically clean area before the equipment was taken to the WCF for the actual inspection. During the inspections, essential information was obtained regarding the cleanliness, structural integrity, in-leakage of ground water, indications of process leaks, indications of corrosion, radiation levels and the general condition of the cells and equipment. In general, the cells contain a great deal of dust and debris, as well as hand tools, piping and miscellaneous equipment. Although the building appears to be structurally sound, the paint is peeling to some degree in all of the cells. Cracking and spalling of the concrete walls is evident in every cell, although the east wall of the off-gas cell is the worst. The results of the completed inspections and lessons learned will be used to plan future activities for stabilization and deactivation of the facility. Remote clean-up of loose piping, hand tools, and miscellaneous debris can start immediately while information from the inspections is factored into the conceptual design for deactivating the facility

  15. Synthesis and calcinations effects on size analysis of Co{sub 3}O{sub 4} nanospheres and their superparamagnetic behaviors

    Energy Technology Data Exchange (ETDEWEB)

    Anandha Babu, G. [Department of Physics, Alagappa University, Karaikudi 630004, Tamil Nadu (India); Ravi, G., E-mail: gravicrc@gmail.com [Department of Physics, Alagappa University, Karaikudi 630004, Tamil Nadu (India); Hayakawa, Y. [Research Institute of Electronics, Shizuoka University, Hamamatsu 432-8011 (Japan); Kumaresavanji, M. [IFIMUP and IN-Institute of Nanoscience and Nanotechnology, Department of Physics and Astronomy, University of Porto, 687 Rua Campo Alegre, 4169-007 Porto (Portugal)

    2015-02-01

    Co{sub 3}O{sub 4} nanoparticles were synthesized by microwave process using citric acid as a capping agent. Interestingly, when calcination temperature is increased to 600 °C, nanoparticles were formed into nanospheres of about less than 20 nm observed from SEM images. The particles were aggregated into bigger size of about 65 nm when the calcination temperature was increased to 800 °C. The samples calcined at 400 °C and 800 °C show superparamagnetism above the blocking temperature and the existence of small ferromagnetism is observed when Tcalcination temperature of the sample. - Highlights: • Spinel Co{sub 3}O{sub 4} nanoparticles are synthesized by fast and effective microwave route. • Tuning of size and morphology of Co{sub 3}O{sub 4} was investigated by calcination temperatures. • Well defined sphere morphology was achieved for the calcinations of 600 °C. • The prepared Co{sub 3}O{sub 4} was modified into moderate size of less than 20 nm for 600 °C. • The 600 °C calcined sample completely obeys superparamagnetism nature from 5K–300K.

  16. Calcination-Digestion-Desliming of Phosphorus Ore Bearing Rare Earth

    Institute of Scientific and Technical Information of China (English)

    Zhang Qin; Zhang Jie; Wang Jing; Qiu Yue qin

    2004-01-01

    The recoveries of phosphorus and RE of ore from Zhijin in Guizhou were studied.The influences of the calcination temperature, resident time, the digested time and water volume of the calcinating on concentrate yield by desliming were also investigated by orthogonal design.Appropriate calcination temperature is initial condition that makes carbonate mineral decomposition.The recovery of phosphorus is 83.02% and rare earth is 90.56% in phosphorus concentrate when calcined temperature is 900 ℃, other conditions include: calcined time is 30 min, digestion water volume is 300 ml, digestion time is 20 min.The results show that the pre-treatment of the ore is favorable for the separation and enrichment of rare earth from phosphorus ore, and a process of calcination-digestion-desliming was promised.

  17. Calcination of liquid radioactive wastes. Part II

    International Nuclear Information System (INIS)

    An attempt is made to design a universal modular system of machine equipment for processing wastes of different composition. First-stage concentration of radioactive wastes is assumed to 200 - 500 kg/m3 which is solved by the inclusion in the system of a single-stage circulation evaporator. Another equipment is the intermittently operating charging reactor with a high-speed stirrer for denitration or other chemical treatment. The types of mixers and the geometrical configuration of the system are described in detail. Also described is the equipment for water evaporation from the chemically treated solution. Several types of equipment have been designed for calcination. The most suitable is the equipment using the principle of a film evaporator. Several solutions are described which comprise the basis for the horizontal calciner for processing 10 l of active wastes per hour with several variants of sealings and heating systems. The performance tests of the equipment were successful in active and non-active operation. (M.D.)

  18. Leaching characteristics of Idaho Chemical Processing Plant calcines

    International Nuclear Information System (INIS)

    This report documents leaching studies conducted on two non-radioactive, pilot-plant calcines produced at the Idaho Chemical Processing Plant. The two pilot-plant calcines simulate radioactive calcine which may be produced in the New Waste Calcining Facility by blending high-level liquid waste and sodium-bearing liquid waste. The calcines were subjected to the Environmental Protection Agency's Extraction Procedure Toxicity Test and to a test based on the Materials Characterization Center's MCC-1 Static Leach Test. Following the protocol of these tests, leachates were obtained and analyzed for chemical composition to develop information about component mass loss and total mass loss. Surface analysis techniques were employed in an attempt to identify species that were leached from the calcines, but later precipitated during the MCC-1 tests. This report also documents leaching studies conducted on a radioactive fluorinel-sodium blend calcine produced in the New Waste Calcining Facility. This calcine was also subjected to a static leach test based on the MCC-1 test. The leachate was analyzed to develop information about total mass loss and leaching characteristics of radioactive species. 12 refs., 9 figs., 9 tabs

  19. Product removal and solids transport from fluidized-bed calciners

    International Nuclear Information System (INIS)

    Methods of removing the solid product from pilot-plant and production fluidized-bed calciners, and transporting product to underground storage vaults are reported here. Testing of dense-phase solids transport systems in test loops during development of a 15-cm-diam. and 30-cm-diam. calciner are described. A lean-phase solid transport system is used with the Waste Calcining Facility. The results of some recent tests done in a lean-phase transport system connected to the 30-cm-diam. calciner are included in this report

  20. Recent advances in spray calcination of nuclear wastes

    International Nuclear Information System (INIS)

    Developments over the last two decades have led to the recent successful demonstration of large-scale spray calcination equipment. The calcination process is ready for full-scale radioactive plant application. The spray calciner is a relatively simple machine. Its components are few and uncomplicated; thus maintenance is minimal, and the equipment lends itself well to remote use. Perhaps the most attractive feature of the spray calciner is its ability to accept an extremely wide range of liquid waste feed compositions. A flow control valve has previously been used to regulate the feed rate to the calciner. Recent tests demonstrate that this item may be eliminated from the feed line, thereby simplifying the overall process flowsheet. Regulation of the atomizing gas-to-liquid feed line pressures can accurately control the liquid flow rate to the calciner. Various types of spray nozzles further allow flexibility in system design. An internal mix nozzle allows the system to operate using a pressurized feed system. Nozzle abrasion has been essentially eliminated by ceramic nozzle inserts. Designs of nonpressurized feed systems have been demonstrated. To insure negligible calcine holdup on the spray chamber wall, pneumatic vibrators have been successfully used for several years without problems. Studies have now been completed based upon vibrator tests to ascertain the long-term effect of vibrator operation on the calcination system. Results indicate that the spray calciner design would not be adversely affected by vibrator operation over a typical 20-year plant life cycle

  1. Leaching characteristics of Idaho Chemical Processing Plant calcines

    Energy Technology Data Exchange (ETDEWEB)

    Chipman, N A

    1990-02-01

    This report documents leaching studies conducted on two non-radioactive, pilot-plant calcines produced at the Idaho Chemical Processing Plant. The two pilot-plant calcines simulate radioactive calcine which may be produced in the New Waste Calcining Facility by blending high-level liquid waste and sodium-bearing liquid waste. The calcines were subjected to the Environmental Protection Agency's Extraction Procedure Toxicity Test and to a test based on the Materials Characterization Center's MCC-1 Static Leach Test. Following the protocol of these tests, leachates were obtained and analyzed for chemical composition to develop information about component mass loss and total mass loss. Surface analysis techniques were employed in an attempt to identify species that were leached from the calcines, but later precipitated during the MCC-1 tests. This report also documents leaching studies conducted on a radioactive fluorinel-sodium blend calcine produced in the New Waste Calcining Facility. This calcine was also subjected to a static leach test based on the MCC-1 test. The leachate was analyzed to develop information about total mass loss and leaching characteristics of radioactive species. 12 refs., 9 figs., 9 tabs.

  2. Rational Aggregation

    OpenAIRE

    Bruce Chapman

    2002-01-01

    In two recent papers, Christian List and Philip Pettit have argued that there is a problem in the aggregation of reasoned judgements that is akin to the aggregation of the preference problem in social choice theory.1 Indeed, List and Pettit prove a new general impossibility theorem for the aggregation of judgements, and provide a propositional interpretation of the social choice problem that suggests it is a special case of their impossibility result.2 Specifically, they show that no judgemen...

  3. Practical results of the MESA 1 line calcinator trial operation

    International Nuclear Information System (INIS)

    Mobile calcination and cementation unit MESA 1 was designed and built by UJV Rez in cooperation with many enterprises, mainly with the Kralovopolske Strojirny Brno. This facility for direct fixation of liquid radioactive wastes was experimentally tested using model non-radioactive solutions and model and actual wastes from the Jaslovske Bohunice nuclear power plant. The calciner was run in trial operation at the Kralovopolske SAtrojirny Brno. A total of 1.3 m3 of model solutions was processed into 180 kg of calcinate. The fixation of the calcinate in cement, the times of solidification and of hardening and the moisture content of concrete blocks were studied. The application was also tested of the calciner in drying ion exchangers from WWER-440 prior to their bituminization. Following the despatch of the cementation module to the Chernobyl nuclear power plant, the direct calcination module was tested at Dukovany together with an auxiliary module which makes possible self-contained calciner operation. Model non-radioactive solutions from the Dukovany nuclear power plant were treated containing H3BO3 and NaNO3 as main components. The usability in actual conditions of the mobile calcination and cementation unit for radioactive wastes was tested in a total of about 70 operating hours. (E.S.). 2 figs., 2 refs

  4. Calcination of kaolinite clay particles for cement production

    DEFF Research Database (Denmark)

    Gebremariam, Abraham Teklay; Yin, Chungen; Rosendahl, Lasse;

    2014-01-01

    Kaolinite rich clay particles calcined under certain conditions can attain favorable pozzolanic properties and can be used to substitute part of the CO2 intensive clinker in cement production. To better guide calcination of a clay material, a transient one-dimensional single particle model...

  5. Modeling of calcination of single kaolinitic clay particle

    DEFF Research Database (Denmark)

    Gebremariam, Abraham Teklay; Yin, Chungen; Rosendahl, Lasse

    The present work aims at modeling of the calcination (dehydroxylation) process of clay particles, specifically kaolinite, and its thermal transformation. For such purpose, 1D single particle calcination model was developed based on the concept of shrinking core model to assess the dehydroxylation...

  6. Mission Need Statement: Calcine Disposition Project Major Systems Acquisition Project

    International Nuclear Information System (INIS)

    This document identifies the need to establish the Calcine Disposition Project to determine and implement the final disposition of calcine including characterization, retrieval, treatment (if necessary), packaging, loading, onsite interim storage pending shipment to a repository or interim storage facility, and disposition of related facilities

  7. Calcination processing method and calcination processing device for radioactive solid wastes

    International Nuclear Information System (INIS)

    In a calcination method of heating radioactive solid wastes comprising mixed organic and inorganic materials to thermally decompose organic materials in wastes, the temperature of the radioactive solid wastes is measured upon heating the radioactive solid wastes, and the amount of heat to be applied to wastes is controlled based on the measured value, and the atmosphere of the circumference of the wastes is cooled to suppress the temperature elevation rate of the wastes. In addition, the oxygen concentration in generated off gases is measured and the amount of heat to be applied to the wastes is controlled depending on the change of the oxygen concentration during calcination. Further, the concentration of gaseous carbon dioxide in the generated off gases is also measured to judge the completion of the calcination by the change of the concentration of the gaseous carbon dioxide. With such procedures, even if the wastes to be treated are radioactive solid wastes in which organic and inorganic materials are mixed with less burnable organic materials, stable and safe operation can be conducted. (T.M.)

  8. Properties of Formula 127 glass prepared with radioactive zirconia calcine

    International Nuclear Information System (INIS)

    Formula 127 glass has been developed to immobilize ICPP zirconia calcine. This glass has been prepared remotely on a laboratory scale basis with actual radioactive zirconia calcine retrieved after ten years of storage from Bin Set 2. The aqueous leachability of the glass produced was investigated and compared through application of the MCC-1, MCC-2 and Soxhlet leach tests with that of Formula 127 glass prepared with simulated calcine. The solid state properties of the glasses prepared with actual and simulated calcines were also measured by electron spectroscopy for chemical analysis (ESCA) and scanning electron microscopy energy dispersive x-ray (SEM-EDX). Based on the application of these leaching tests and analysis techniques the properties measured in this study are similar for 127 glass prepared with either simulated or radioactive calcine. 13 figures, 16 tables

  9. Weighted aggregation

    Science.gov (United States)

    Feiveson, A. H. (Principal Investigator)

    1979-01-01

    The use of a weighted aggregation technique to improve the precision of the overall LACIE estimate is considered. The manner in which a weighted aggregation technique is implemented given a set of weights is described. The problem of variance estimation is discussed and the question of how to obtain the weights in an operational environment is addressed.

  10. Calcination of Radioactive Waste in Molten Sulphur

    International Nuclear Information System (INIS)

    The Savannah River Laboratory is developing a novel process based on the unique properties of sulphur for converting radioactive wastes to a solid form of low solubility for ''ultimate'' disposal. In this process the aqueous acidic wastes are reacted with molten sulphur at 150°C so that the water and volatile acids are driven off and the chemical compounds present in the waste are calcined and/or chemically reduced. The resulting sulphur-waste slurry is then heated at 400 to 444°C for from 1 to 5 hr to drive off sulphuric acid and residual water and further calcine and/or reduce the chemical compounds in the sulphur-waste slurry. In these steps the molten sulphur serves as a heat-transfer medium, prevents the entrainment of the radioactive solids in the steam and reaction gases and eliminates the volatilization of radioactive ruthenium by preventing the formation of the tetroxide. Laboratory scale runs with concentrated high activity waste as feed (1.3 x 109 γ c/(min)(ml), 2.0M Al(N03)3, and 1.5M HNO3) have shown that only one part in approximately 100 000 parts of the activity in the feed is carried overhead in the off-gas in these process steps. After the completion of the high-temperature treatment, the sulphur-waste slurry is cooled to 120-150°C and transferred as a liquid to the final containment system where it is allowed to solidify. Although it is our intent to protect the containment system against the action of water, the resistance of the solidified sulphur- waste slurry to the action of water has been used as a measure of the effectiveness of this process. Small cylinders of the solidified slurry have been prepared from simulated wastes containing Al (NO3)3 or dissolved stainless-steel nitrates with tracer levels of Sr and Cs, and for concentrated high-activity waste containing Al(NO3s)3. These cylinders have been exposed to water over extended periods of time. Leaching rates are calculated as, though there is complete removal of material from a

  11. Enhanced Photocatalytic Activity of Powders (P25 via Calcination Treatment

    Directory of Open Access Journals (Sweden)

    Guohong Wang

    2012-01-01

    Full Text Available P25 TiO2 powders were calcined at different temperatures in a muffle furnace in air. The P25 powders before and after calcination treatment were characterized with XRD FTIR, UV-visible diffuse reflectance spectra, SEM, TEM, HRTEM, and N2 adsorption-desorption measurements. The photocatalytic activity was evaluated by the photocatalytic oxidation of methyl orange aqueous solution under UV light irradiation in air. The results showed that calcination treatment obviously influenced the microstructures and photocatalytic activity of the P25 TiO2 powders. The synergistic effect of the phase structure, BET surface area, and crystallinity on the photocatalytic of TiO2 powders (P25 after calcination was investigated. An optimal calcination temperature ( was determined. The photocatalytic activity of TiO2 powders calcined at was nearly 2 times higher than that of the uncalcined P25 TiO2. The highest photocatalytic activities of the calcined samples at for 4 h might be ascribed to the enhancement of anatase crystallization and the optimal mass ratio (ca. 1 : 2 of rutile to anatase.

  12. Calcination/dissolution testing for Hanford Site tank wastes

    Energy Technology Data Exchange (ETDEWEB)

    Colby, S.A.; Delegard, C.H. [Westinghouse Hanford Co., Richland, WA (United States); McLaughlin, D.F. [Westinghouse Science and Technology Center, Pittsburgh, PA (United States); Danielson, M.J. [Pacific Northwest Lab., Richland, WA (United States)

    1994-07-01

    Thermal treatment by calcination offers several benefits for the treatment of Hanford Site tank wastes, including the destruction of organics and ferrocyanides and an hydroxide fusion that permits the bulk of the mostly soluble nonradioactive constituents to be easily separated from the insoluble transuranic residue. Critical design parameters were tested, including: (1) calciner equipment design, (2) hydroxide fusion chemistry, and (3) equipment corrosion. A 2 gal/minute pilot plant processed a simulated Tank 101-SY waste and produced a free flowing 700 C molten calcine with an average calciner retention time of 20 minutes and >95% organic, nitrate, and nitrite destruction. Laboratory experiments using actual radioactive tank waste and the simulated waste pilot experiments indicate that 98 wt% of the calcine produced is soluble in water, leaving an insoluble transuranic fraction. All of the Hanford Site tank wastes can benefit from calcination/dissolution processing, contingent upon blending various tank waste types to ensure a target of 70 wt% sodium hydroxide/nitrate/nitrite fluxing agent. Finally, corrosion testing indicates that a jacketed nickel liner cooled to below 400 C would corrode <2 mil/year (0.05 mm/year) from molten calcine attack.

  13. Summary of Calcine Disposal Development Using Hot Isostatic Pressing

    Energy Technology Data Exchange (ETDEWEB)

    Bateman, Ken [Idaho National Lab. (INL), Idaho Falls, ID (United States); Wahlquist, Dennis [Idaho National Lab. (INL), Idaho Falls, ID (United States); Hart, Edward [Idaho National Lab. (INL), Idaho Falls, ID (United States); McCartin, William [Idaho National Lab. (INL), Idaho Falls, ID (United States)

    2015-03-01

    Battelle Energy Alliance, LLC, has demonstrated the effectiveness of the hot isostatic press (HIP) process for treatment of hazardous high-level waste known as calcine that is stored at the Idaho Nuclear Technology and Engineering Center (INTEC) at Idaho National Laboratory. HIP trials performed with simulated calcines at Idaho National Laboratory’s Materials and Fuels Complex and an Australian Nuclear Science and Technology Organization facility from 2007 to 2010 produced a dense, monolithic waste form with increased chemical durability and effective (storage) volume reductions of ~10 to ~70% compared to granular calcine forms. In December 2009, the U.S. Department of Energy signed an amended Record of Decision selecting HIP technology as the treatment method for the 4,400 m3 of granular zirconia and alumina calcine stored at INTEC. Testing showed that HIP treatment reduces the risks associated with radioactive and hazardous constituent release, post-production handling, and long-term (repository) storage of calcines and would result in estimated storage cost savings in the billions of dollars. Battelle Energy Alliance has the ability to complete pilot-scale HIP processing of INTEC calcine, which is the next necessary step in implementing HIP processing as a calcine treatment method.

  14. Structural Integrity Program for INTEC Calcined Solids Storage Facilities

    Energy Technology Data Exchange (ETDEWEB)

    Jeffrey Bryant

    2008-08-30

    This report documents the activities of the structural integrity program at the Idaho Nuclear Technology and Engineering Center relevant to the high-level waste Calcined Solids Storage Facilities and associated equipment, as required by DOE M 435.1-1, 'Radioactive Waste Management Manual'. Based on the evaluation documented in this report, the Calcined Solids Storage Facilities are not leaking and are structurally sound for continued service. Recommendations are provided for continued monitoring of the Calcined Solids Storage Facilities.

  15. Aggregate productivity and aggregate technology

    OpenAIRE

    Susanto Basu; John G. Fernald

    1997-01-01

    Aggregate productivity and aggregate technology are meaningful but distinct concepts. We show that a slightly-modified Solow productivity residual measures changes in economic welfare, even when productivity and technology differ because of distortions such as imperfect competition. We then present a general accounting framework that identifies several new non-technological gaps between productivity and technology, gaps reflecting imperfections and frictions in output and factor markets. Empi...

  16. CSER 97-004: PFP production denitration calciner system

    International Nuclear Information System (INIS)

    The plutonium stabilization program at the Plutonium Finishing Plant (PFP) includes conversion of acidic plutonium nitrate solution into plutonium oxide. Conversion is facilitated through use of a vertical calciner installed in Glovebox HC-23OC-2, which is located in RM 230C of this facility. This evaluation supports the Criticality Prevention Specification for the calcining process inside this glovebox. As the product of the calciner is a high density plutonium oxide, a number of limits are required to insure criticality safety. The containers allowed are product receiver vessels and 0.5 C slip lid cans and polyjars. The limits allow for two ''unit masses'' of 2 V total volume each, separated by a distance of at least 25.4 cm (10 in.). This evaluation allows for operation of the calciner for product densities not in excess of 5.5 g Pu/cm3

  17. CSER 99-001: PFP LAB Dentirating calciner

    International Nuclear Information System (INIS)

    A criticality safety evaluation report was prepared for the Plutonium Finishing Plant (PFP) laboratory denigrating calciner, located in Glovebox 188-1, that converts Pu(NO3)4 solutions to the high fired stable oxide PuO2. Fissile mass limits and volume limits are set for the glovebox for testing operations and training operators using only nitric acid feed to a plutonium oxide bed in the calciner

  18. CSER 99-001: PFP LAB Dentirating calciner

    Energy Technology Data Exchange (ETDEWEB)

    MILLER, E.M.; DOBBIN, K.D.

    1999-02-22

    A criticality safety evaluation report was prepared for the Plutonium Finishing Plant (PFP) laboratory denigrating calciner, located in Glovebox 188-1, that converts Pu(NO{sub 3}){sub 4} solutions to the high fired stable oxide PuO{sub 2}. Fissile mass limits and volume limits are set for the glovebox for testing operations and training operators using only nitric acid feed to a plutonium oxide bed in the calciner.

  19. Mechanism of boron uptake by hydrocalumite calcined at different temperatures.

    Science.gov (United States)

    Qiu, Xinhong; Sasaki, Keiko; Takaki, Yu; Hirajima, Tsuyoshi; Ideta, Keiko; Miyawaki, Jin

    2015-04-28

    Hydrocalumite (Ca-Al-layered double hydroxide (LDH)) was prepared and applied for the removal of borate. The properties of Ca-Al-LDH calcined at different temperatures were diverse, which affected the sorption density and mechanism of boron species. The sorption density increased with increase in calcined temperature and the sample calcined at 900°C (Ca-Al-LDH-900) showed the maximum sorption density in this work. The solid residues after sorption were characterized by (11)B NMR, (27)Al NMR, SEM, and XRD to investigate the sorption mechanism. Dissolution-reprecipitation was the main mechanism for sorption of borate in Ca-Al-LDH. For Ca-Al-LDH calcined at 300 and 500°C, regeneration occurred in a short time and the newly forming LDHs were decomposed to release Ca(2+) ions and formed ettringite with borate. Two stages occurred in the sorption of boron by Ca-Al-LDH calcined at 900°C. In the first stage, boron species adsorbed on the alumina gel resulting from the hydration of calcined products. In this stage, borate was included as an interlayer anion into the newly forming LDHs in the following stage, and then immobilized as HBO3(2-) into the interlayer, most the LDHs. PMID:25661174

  20. Lightweight alumina refractory aggregate. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Swansiger, T.G.; Pearson, A.

    1996-07-16

    Objective was to develop a lightweight, high alumina refractory aggregate for use in various high performance insulating (low thermal conductivity) refractory applications (e.g., in the aluminium, glass, cement, and iron and steel industries). A new aggregate process was developed through bench and pilot-scale experiments involving extrusion of a blend of calcined and activated alumina powders and organic extrusion aids and binders. The aggregate, with a bulk density approaching 2.5 g/cc, exhibited reduced thermal conductivity and adequate fired strength compared to dense tabular aggregate. Refractory manufacturers were moderately enthusiastic over the results. Alcoa prepared an economic analysis for producing lightweight aggregate, based on a retrofit of this process into existing Alcoa production facilities. However, a new, competing lightweight aggregate material was developed by another company; this material (Plasmal{trademark})had a significantly more favorable cost base than the Alcoa/DOE material, due to cheap raw materials and fewer processing steps. In late 1995, Alcoa became a distributor of Plasmal. Alcoa estimated that {ge}75% of the market originally envisioned for the Alcoa/DOE aggregate would be taken by Plasmal. Hence, it was decided to terminate the contract without the full- scale demonstration.

  1. Mechanism of boron uptake by hydrocalumite calcined at different temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Qiu, Xinhong, E-mail: qxinhong@gmail.com [Department of Earth Resources Engineering, Kyushu University,Fukuoka 819-0395 (Japan); Sasaki, Keiko; Takaki, Yu; Hirajima, Tsuyoshi [Department of Earth Resources Engineering, Kyushu University,Fukuoka 819-0395 (Japan); Ideta, Keiko; Miyawaki, Jin [Institute for Materials Chemistry and Engineering, Kyushu University, Kasuga 816-8180 (Japan)

    2015-04-28

    Highlights: • Higher sorption density of borate was observed at higher calcination temperature. • Sorption of borate by Ca-Al-LDH was mainly through DR mechanism. • Removal of borate by Ca-LDH-300 and Ca-LDH-500 were through forming of ettringite. • Boron was mainly adsorbed and intercalated into hydration of Ca-Al-LDH-900. - Abstract: Hydrocalumite (Ca-Al-layered double hydroxide (LDH)) was prepared and applied for the removal of borate. The properties of Ca-Al-LDH calcined at different temperatures were diverse, which affected the sorption density and mechanism of boron species. The sorption density increased with increase in calcined temperature and the sample calcined at 900 °C (Ca-Al-LDH-900) showed the maximum sorption density in this work. The solid residues after sorption were characterized by {sup 11}B NMR, {sup 27}Al NMR, SEM, and XRD to investigate the sorption mechanism. Dissolution–reprecipitation was the main mechanism for sorption of borate in Ca-Al-LDH. For Ca-Al-LDH calcined at 300 and 500 °C, regeneration occurred in a short time and the newly forming LDHs were decomposed to release Ca{sup 2+} ions and formed ettringite with borate. Two stages occurred in the sorption of boron by Ca-Al-LDH calcined at 900 °C. In the first stage, boron species adsorbed on the alumina gel resulting from the hydration of calcined products. In this stage, borate was included as an interlayer anion into the newly forming LDHs in the following stage, and then immobilized as HBO{sub 3}{sup 2−} into the interlayer, most the LDHs.

  2. Mechanism of boron uptake by hydrocalumite calcined at different temperatures

    International Nuclear Information System (INIS)

    Highlights: • Higher sorption density of borate was observed at higher calcination temperature. • Sorption of borate by Ca-Al-LDH was mainly through DR mechanism. • Removal of borate by Ca-LDH-300 and Ca-LDH-500 were through forming of ettringite. • Boron was mainly adsorbed and intercalated into hydration of Ca-Al-LDH-900. - Abstract: Hydrocalumite (Ca-Al-layered double hydroxide (LDH)) was prepared and applied for the removal of borate. The properties of Ca-Al-LDH calcined at different temperatures were diverse, which affected the sorption density and mechanism of boron species. The sorption density increased with increase in calcined temperature and the sample calcined at 900 °C (Ca-Al-LDH-900) showed the maximum sorption density in this work. The solid residues after sorption were characterized by 11B NMR, 27Al NMR, SEM, and XRD to investigate the sorption mechanism. Dissolution–reprecipitation was the main mechanism for sorption of borate in Ca-Al-LDH. For Ca-Al-LDH calcined at 300 and 500 °C, regeneration occurred in a short time and the newly forming LDHs were decomposed to release Ca2+ ions and formed ettringite with borate. Two stages occurred in the sorption of boron by Ca-Al-LDH calcined at 900 °C. In the first stage, boron species adsorbed on the alumina gel resulting from the hydration of calcined products. In this stage, borate was included as an interlayer anion into the newly forming LDHs in the following stage, and then immobilized as HBO32− into the interlayer, most the LDHs

  3. High Temperature Calcination - MACT Upgrade Equipment Pilot Plant Test

    Energy Technology Data Exchange (ETDEWEB)

    Richard D. Boardman; B. H. O& #39; Brien; N. R. Soelberg; S. O. Bates; R. A. Wood; C. St. Michel

    2004-02-01

    About one million gallons of acidic, hazardous, and radioactive sodium-bearing waste are stored in stainless steel tanks at the Idaho Nuclear Technology and Engineering Center (INTEC), which is a major operating facility of the Idaho National Engineering and Environmental Laboratory. Calcination at high-temperature conditions (600 C, with alumina nitrate and calcium nitrate chemical addition to the feed) is one of four options currently being considered by the Department of Energy for treatment of the remaining tank wastes. If calcination is selected for future processing of the sodium-bearing waste, it will be necessary to install new off-gas control equipment in the New Waste Calcining Facility (NWCF) to comply with the Maximum Achievable Control Technology (MACT) standards for hazardous waste combustors and incinerators. This will require, as a minimum, installing a carbon bed to reduce mercury emissions from their current level of up to 7,500 to <45 {micro}g/dscm, and a staged combustor to reduce unburned kerosene fuel in the off-gas discharge to <100 ppm CO and <10 ppm hydrocarbons. The staged combustor will also reduce NOx concentrations of about 35,000 ppm by 90-95%. A pilot-plant calcination test was completed in a newly constructed 15-cm diameter calciner vessel. The pilot-plant facility was equipped with a prototype MACT off-gas control system, including a highly efficient cyclone separator and off-gas quench/venturi scrubber for particulate removal, a staged combustor for unburned hydrocarbon and NOx destruction, and a packed activated carbon bed for mercury removal and residual chloride capture. Pilot-plant testing was performed during a 50-hour system operability test January 14-16, followed by a 100-hour high-temperature calcination pilot-plant calcination run January 19-23. Two flowsheet blends were tested: a 50-hour test with an aluminum-to-alkali metal molar ratio (AAR) of 2.25, and a 50-hour test with an AAR of 1.75. Results of the testing

  4. Calcined Waste Storage at the Idaho Nuclear Technology and Engineering Center

    Energy Technology Data Exchange (ETDEWEB)

    Staiger, M. Daniel, Swenson, Michael C.

    2011-09-01

    This comprehensive report provides definitive volume, mass, and composition (chemical and radioactivity) of calcined waste stored at the Idaho Nuclear Technology and Engineering Center. Calcine composition data are required for regulatory compliance (such as permitting and waste disposal), future treatment of the caline, and shipping the calcine to an off-Site-facility (such as a geologic repository). This report also contains a description of the calcine storage bins. The Calcined Solids Storage Facilities (CSSFs) were designed by different architectural engineering firms and built at different times. Each CSSF has a unique design, reflecting varying design criteria and lessons learned from historical CSSF operation. The varying CSSF design will affect future calcine retrieval processes and equipment. Revision 4 of this report presents refinements and enhancements of calculations concerning the composition, volume, mass, chemical content, and radioactivity of calcined waste produced and stored within the CSSFs. The historical calcine samples are insufficient in number and scope of analysis to fully characterize the entire inventory of calcine in the CSSFs. Sample data exist for all the liquid wastes that were calcined. This report provides calcine composition data based on liquid waste sample analyses, volume of liquid waste calcined, calciner operating data, and CSSF operating data using several large Microsoft Excel (Microsoft 2003) databases and spreadsheets that are collectively called the Historical Processing Model. The calcine composition determined by this method compares favorably with historical calcine sample data.

  5. Human health risk characterization of petroleum coke calcining facility emissions.

    Science.gov (United States)

    Singh, Davinderjit; Johnson, Giffe T; Harbison, Raymond D

    2015-12-01

    Calcining processes including handling and storage of raw petroleum coke may result in Particulate Matter (PM) and gaseous emissions. Concerns have been raised over the potential association between particulate and aerosol pollution and adverse respiratory health effects including decrements in lung function. This risk characterization evaluated the exposure concentrations of ambient air pollutants including PM10 and gaseous pollutants from a petroleum coke calciner facility. The ambient air pollutant levels were collected through monitors installed at multiple locations in the vicinity of the facility. The measured and modeled particulate levels in ambient air from the calciner facility were compared to standards protective of public health. The results indicated that exposure levels were, on occasions at sites farther from the facility, higher than the public health limit of 150 μg/m(3) 24-h average for PM10. However, the carbon fraction demonstrated that the contribution from the calciner facility was de minimis. Exposure levels of the modeled SO2, CO, NOx and PM10 concentrations were also below public health air quality standards. These results demonstrate that emissions from calcining processes involving petroleum coke, at facilities that are well controlled, are below regulatory standards and are not expected to produce a public health risk. PMID:26520182

  6. Apatite formation on calcined kaolin-white Portland cement geopolymer.

    Science.gov (United States)

    Pangdaeng, S; Sata, V; Aguiar, J B; Pacheco-Torgal, F; Chindaprasirt, P

    2015-06-01

    In this study, calcined kaolin-white Portland cement geopolymer was investigated for use as biomaterial. Sodium hydroxide and sodium silicate were used as activators. In vitro test was performed with simulated body fluid (SBF) for bioactivity characterization. The formation of hydroxyapatite bio-layer on the 28-day soaked samples surface was tested using SEM, EDS and XRD analyses. The results showed that the morphology of hydroxyapatite was affected by the source material composition, alkali concentration and curing temperature. The calcined kaolin-white Portland cement geopolymer with relatively high compressive strength could be fabricated for use as biomaterial. The mix with 50% white Portland cement and 50% calcined kaolin had 28-day compressive strength of 59.0MPa and the hydroxyapatite bio-layer on the 28-day soaked sample surface was clearly evident. PMID:25842101

  7. Talc-based cementitious products: Effect of talc calcination

    Directory of Open Access Journals (Sweden)

    C.J. Ngally Sabouang

    2015-09-01

    Full Text Available This study reports the use of calcined talc for cementitious products making. The calcination is used to enhance the availability of magnesium from talc to react with phosphate for cement phase formation. It is shown that previous calcination of talc leads to products having enhanced mechanical performance due to the formation of more cement phase than in products based on raw talc. Talc fired at 900 °C was found to be the one in which magnesium release was maximal. Firing at temperature higher than 900 °C leads to the stabilization of enstatite, which decreased the magnesium availability. The cement phase is struvite, which was better detected on the X-ray patterns of the products involving fired talc. All the products have very rapid setting time and low shrinkage.

  8. Letter report: Evaluation of dryer/calciner technologies for testing

    International Nuclear Information System (INIS)

    This letter report describes some past experiences on the drying and calcination of radioactive materials or corresponding simulants; and the information needed from testing. The report also includes an assessment of informational needs including possible impacts to a full-scale plant. This includes reliability, maintenance, and overall size versus throughput. Much of the material was previously compiled and reported by Mike Elliott of PNL open-quotes Melter Performance Assessmentclose quotes and Larry Eisenstatt of SEG on contract to WHC in a letter to Rod Powell. Also, an annotated bibliography was prepared by Reagan Seymour of WHC. Descriptions of the drying and calciner technologies, development status, advantages and disadvantages of using a WFE or calciner, and recommendations for future testing are discussed in this report

  9. Fluidized bed system for calcination of high level radioactive waste

    International Nuclear Information System (INIS)

    During the operation of nuclear facilities significant quantities of radiochemical liquid effluents of different concentrations and varying chemical compositions are generated. These effluents contain activated radionuclides, corrosion products and fission products. The advantage of feeding the waste in solid form into the vitrifying equipment are multifold. Efforts are therefore made in many countries to calcine the high level waste, and obtain waste in the oxide form before the same is mixed with glass forming additives and fed into the melter unit. An experimental rig for fluidized bed calcination is constructed for carrying out the detailed investigation of this process, in order to adopt the same for plant scale application. To achieve better gas-solid contact and avoid raining down of solids, a distributor of bubble cap type was designed. A review of existing experience at various laboratories and design of new experimental facility for development of calciners are given. (author)

  10. Total oxidation of toluene over calcined trimetallic hydrotalcites type catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Palacio, Luz A. [Instituto Superior Tecnico, IBB - Centro de Engenharia Biologica e Quimica, Universidade Tecnica de Lisboa, Av. Rovisco Pais, 1049-001 Lisboa (Portugal); Grupo Catalizadores y Adsorbentes, Universidad de Antioquia 1-317, A.A. 1226 Medellin (Colombia); Velasquez, Juliana; Echavarria, Adriana [Grupo Catalizadores y Adsorbentes, Universidad de Antioquia 1-317, A.A. 1226 Medellin (Colombia); Faro, Arnaldo [Departamento de Fisicoquimica, Instituto de Quimica, Universidade Federal do Rio de Janeiro, Ilha do Fundao, CT bloco A, Rio de Janeiro (Brazil); Ramoa Ribeiro, F. [Instituto Superior Tecnico, IBB - Centro de Engenharia Biologica e Quimica, Universidade Tecnica de Lisboa, Av. Rovisco Pais, 1049-001 Lisboa (Portugal); Ribeiro, M. Filipa, E-mail: filipa.ribeiro@ist.utl.pt [Instituto Superior Tecnico, IBB - Centro de Engenharia Biologica e Quimica, Universidade Tecnica de Lisboa, Av. Rovisco Pais, 1049-001 Lisboa (Portugal)

    2010-05-15

    Two trimetallic ZnCuAl and MnCuAl hydrotalcites have been successfully synthesized by a co-precipitation method. The manganese based material was identified as a new hydrotalcite phase. Both lamellar precursors were calcined at 450 and 600 deg. C and the resulting catalysts were tested on reaction of total oxidation of toluene. The solids were characterized by X-ray diffraction, thermal analysis, atomic absorption spectroscopy, Fourier transformed infrared spectroscopy, N{sub 2} adsorption and H{sub 2} temperature-programmed reduction. It was found that ZnCuAl materials are composed of copper and zinc oxides supported on alumina; while MnCuAl ones comprise basically spinel phases, which were not completely identified. The catalytic behavior of the calcined samples showed that Mn hydrotalcite calcined at 450 deg. C exhibited the best catalytic performance that corresponds to 100% toluene conversion into CO{sub 2} at about 300 deg. C.

  11. Spray calcination/in-can melting: effluent characterization and treatment

    International Nuclear Information System (INIS)

    According to data obtained during calcination of nonradioactive, simulated waste, ruthenium and cesium losses from the spray calciner are small, on the order of 3.5 x 10-2% and 3.4 x 10-2%, respectively. Calciner-melter and filter decontamination factors for ruthenium and cesium averaged 3.6 x 104 and 3.9 x 104, respectively. Particulate decontamination factors of 103 to 104 have been obtained using sintered stainless steel filters. A significant portion of the ruthenium and cesium lost to the process off-gas system was due to particle penetration of the filters. The particles penetrating the filters have a mass distribution centering about a size large enough to control with available technology. Processing wastes containing fluoride will probably volatilize a portion of the fluoride to the off-gas system, thus increasing the probability of corrosion problems. 34 figures, 30 tables

  12. CSER 95-005: PFP vertical denitration calciner

    International Nuclear Information System (INIS)

    The Vertical Denitrating Calciner system will stabilize certain unique solutions containing fissile salts by removing the water and nitrate ion to produce a more easily stored powder. This end is achieved by high-firing the solution in the calciner. The resultant calcine is distinguished by particles which are larger and denser than those produced by the more conventional oxalate precipitation process. This criticality safety evaluation report examines criticality safety for the denitration system, installed in glovebox 188-1 at PFP. The examination shows that, due to the incorporation of standard criticality safety design techniques, the glovebox can be maintained subcritical with minimal reliance on administrative controls. The examination also shows that, ignoring the necessary administrative controls can make a criticality possible in glovebox 188-1. Section 3.0 of this report lists the necessary administrative controls

  13. Characterization of Offgas Generated During Calcination of Incinerator Ash Surrogates

    International Nuclear Information System (INIS)

    The Pacific Northwest National Laboratory (PNNL), in cooperation with the Los Alamos National Laboratory (LANL) and Safe Sites of Colorado (SSOC), developed a recommended flowsheet for the processing of plutonium-bearing incinerator ash stored at the Rocky Flats Environmental Technology Site (RFETS) (Lucy et al. 1998). This flowsheet involves a calcination pretreatment step, the purpose of which is to remove carbonaceous material from the incinerator ash. Removal of this material reduced the probability of process upsets, improved product quality, and increases ash waste loading. As part of the continued development of the recommended flowsheet, PNNL performed a series of tests to characterize the offgas generated during the calcination process

  14. Corrosion experience in calcination of liquid nuclear waste

    Energy Technology Data Exchange (ETDEWEB)

    Zimmerman, C A

    1980-01-01

    The Waste Calcining Facility (WCF) at the Idaho National Engineering Laboratory became operational in 1963. Since that time, approximately 13,337,137 litres (3,523,375 gallons) of liquid nuclear wastes, generated during the reprocessing of spent nuclear fuel materials, have been reduced to dry granular solids. The volume reduction is about seven or eight gallons of liquid waste to one gallon of dry granular solids. This paper covers some of the corrosion experiences encountered in over fifteen years of operating that calcination facility. 7 figures, 7 tables.

  15. Corrosion experience in calcination of liquid nuclear waste

    International Nuclear Information System (INIS)

    The Waste Calcining Facility (WCF) at the Idaho National Engineering Laboratory became operational in 1963. Since that time, approximately 13,337,137 litres (3,523,375 gallons) of liquid nuclear wastes, generated during the reprocessing of spent nuclear fuel materials, have been reduced to dry granular solids. The volume reduction is about seven or eight gallons of liquid waste to one gallon of dry granular solids. This paper covers some of the corrosion experiences encountered in over fifteen years of operating that calcination facility. 7 figures, 7 tables

  16. Calcine Waste Storage at the Idaho Nuclear Technology and Engineering Center

    Energy Technology Data Exchange (ETDEWEB)

    M. D. Staiger

    1999-06-01

    A potential option in the program for long-term management of high-level wastes at the Idaho Nuclear Technology and Engineering Center (INTEC), at the Idaho National Engineering and Environmental Laboratory, calls for retrieving calcine waste and converting it to a more stable and less dispersible form. An inventory of calcine produced during the period December 1963 to May 1999 has been prepared based on calciner run, solids storage facilities operating, and miscellaneous operational information, which gives the range of chemical compositions of calcine waste stored at INTEC. Information researched includes calciner startup data, waste solution analyses and volumes calcined, calciner operating schedules, solids storage bin capacities, calcine storage bin distributor systems, and solids storage bin design and temperature monitoring records. Unique information on calcine solids storage facilities design of potential interest to remote retrieval operators is given.

  17. Method for calcining nuclear waste solutions containing zirconium and halides

    Science.gov (United States)

    Newby, Billie J.

    1979-01-01

    A reduction in the quantity of gelatinous solids which are formed in aqueous zirconium-fluoride nuclear reprocessing waste solutions by calcium nitrate added to suppress halide volatility during calcination of the solution while further suppressing chloride volatility is achieved by increasing the aluminum to fluoride mole ratio in the waste solution prior to adding the calcium nitrate.

  18. Restart plan for the prototype vertical denitration calciner

    Energy Technology Data Exchange (ETDEWEB)

    SUTTER, C.S.

    1999-09-01

    Testing activities on the Prototype Vertical Denitration Calciner at PFP were suspended in January 1997 due to the hold on fissile material handling in the facility. The Restart Plan will govern the transition of the test program from the completion of the activity based startup review; through equipment checkout and surrogate material runs; to resumption of the testing program and transition to unrestricted testing.

  19. Screening Level Risk Assessment for the New Waste Calcining Facility

    Energy Technology Data Exchange (ETDEWEB)

    M. L. Abbott; K. N. Keck; R. E. Schindler; R. L. VanHorn; N. L. Hampton; M. B. Heiser

    1999-05-01

    This screening level risk assessment evaluates potential adverse human health and ecological impacts resulting from continued operations of the calciner at the New Waste Calcining Facility (NWCF) at the Idaho Nuclear Technology and Engineering Center (INTEC), Idaho National Engineering and Environmental Laboratory (INEEL). The assessment was conducted in accordance with the Environmental Protection Agency (EPA) report, Guidance for Performing Screening Level Risk Analyses at Combustion Facilities Burning Hazardous Waste. This screening guidance is intended to give a conservative estimate of the potential risks to determine whether a more refined assessment is warranted. The NWCF uses a fluidized-bed combustor to solidify (calcine) liquid radioactive mixed waste from the INTEC Tank Farm facility. Calciner off volatilized metal species, trace organic compounds, and low-levels of radionuclides. Conservative stack emission rates were calculated based on maximum waste solution feed samples, conservative assumptions for off gas partitioning of metals and organics, stack gas sampling for mercury, and conservative measurements of contaminant removal (decontamination factors) in the off gas treatment system. Stack emissions were modeled using the ISC3 air dispersion model to predict maximum particulate and vapor air concentrations and ground deposition rates. Results demonstrate that NWCF emissions calculated from best-available process knowledge would result in maximum onsite and offsite health and ecological impacts that are less then EPA-established criteria for operation of a combustion facility.

  20. Activity Based Startup Plan for Prototype Vertical Denitration Calciner

    International Nuclear Information System (INIS)

    Testing activities on the Prototype Vertical Denitration Calciner at PFP were suspended in January 1997 due to the hold on fissile material handling in the facility. The restart of testing activities will require a review through an activity based startup process based upon Integrated Safety Management (ISM) principles to verify readiness. The Activity Based Startup Plan has been developed for this process

  1. Ninth Processing Campaign in the Waste Calcining Facility

    International Nuclear Information System (INIS)

    This report discusses the Ninth (and final) Processing Campaign at the Waste Calcining Facility. Several processing interruptions were experienced during this campaign and the emphasis of this report is on process and equipment performance with operating problems and corrective actions discussed in detail

  2. Inductive classification of operating data from a fluidized bed calciner

    International Nuclear Information System (INIS)

    A process flowsheet expert system for a fluidized bed calciner which solidifies high-level radioactive liquid waste was developed from pilot-plant data using a commercial, inductive classification program. After initial classification of the data, the resulting rules were inspected and adjusted to match existing knowledge of process chemistry. The final expert system predicts performance of process flowsheets based upon the chemical composition of the calciner feed and has been successfully used to identify potential operational problems prior to calciner pilot-plant testing of new flowsheets and to provide starting parameters for pilot-plant tests. By using inductive classification techniques to develop the initial rules from the calciner pilot-plant data and using existing process knowledge to verify the accuracy of these rules, an effective expert system was developed with a minimum amount of effort. This method may be applied for developing expert systems for other processes where numerous operating data are available and only general process chemistry effects are known

  3. Physical and chemical characterization of synthetic calcined sludge

    International Nuclear Information System (INIS)

    Calcined synthetic sludge was chemically characterized in support of engineering studies to design a processing plant to solidify highly radioactive waste at the Savannah River Plant. An analytical technique is described which provides quantitative data by mass spectrometric analysis of gases evolved during thermogravimetric analysis without measurements of gas flow rates or mass spectrometer sensitivities. Scanning electron microprobe analysis, Mossbauer spectroscopy, and several other common analytical methods were also used. Calcined sludge consists primarily of amorphous particles of hydrous oxides with iron, manganese, nickel, and calcium distributed fairly uniformly throughout the powder. Iron, manganese, nickel, and calcium exist in forms that are highly insoluble in water, but aluminum, sulfate, nitrate, and sodium exhibit relative water solubilities that increase in the given order from 60% to 94%. Evolved gas analysis in a helium atmosphere showed that calcined sludge is completely dehydrated by heating to 4000C, carbon dioxide is evolved between 100 to 7000C with maximum evolution at 5000C, and oxygen is evolved between 400 and 10000C. Evolved gas analyses are also reported for uncalcined sludge. A spinel-type oxide similar to NiFe2O4 was detected by x-ray diffraction analysis at very low-level in calcined sludge

  4. Method of processing liquid radioactive wastes by calcination and vitrification

    International Nuclear Information System (INIS)

    The original liquid radioactive waste is added to the radioactive waste calcinate and glass-forming additions. The said components are converted into a paste form which is proportioned in the melting furnace. Moisturising the mixture with liquid radioactive waste eliminates dust, avoids radionuclide volatility and has an additional advantage that more radioactive waste can be processed. (E.S.)

  5. Restart plan for the prototype vertical denitration calciner

    International Nuclear Information System (INIS)

    Testing activities on the Prototype Vertical Denitration Calciner at PFP were suspended in January 1997 due to the hold on fissile material handling in the facility. The Restart Plan will govern the transition of the test program from the completion of the activity based startup review; through equipment checkout and surrogate material runs; to resumption of the testing program and transition to unrestricted testing

  6. Calcined Waste Storage at the Idaho Nuclear Technology and Engineering Center

    Energy Technology Data Exchange (ETDEWEB)

    M. D. Staiger

    2007-06-01

    This report provides a quantitative inventory and composition (chemical and radioactivity) of calcined waste stored at the Idaho Nuclear Technology and Engineering Center. From December 1963 through May 2000, liquid radioactive wastes generated by spent nuclear fuel reprocessing were converted into a solid, granular form called calcine. This report also contains a description of the calcine storage bins.

  7. Aggregation of Scale Efficiency

    OpenAIRE

    Valentin Zelenyuk

    2012-01-01

    In this article we extend the aggregation theory in efficiency and productivity analysis by deriving solutions to the problem of aggregation of individual scale efficiency measures, primal and dual, into aggregate primal and dual scale efficiency measures of a group. The new aggregation result is coherent with aggregation framework and solutions for the other related efficiency measures that already exist in the literature.

  8. Magnesia formed on calcination of Mg(OH)2 prepared from natural bischofite

    International Nuclear Information System (INIS)

    Calcination of magnesium hydroxide, which was prepared from natural bischofite MgCl2.6H2O, leading to dehydration 2(≡MgOH) → ≡Mg-O-Mg≡ + H2O, is accompanied by transition of phase not only to MgO but also to MgO x at x 4O3) at moderate temperatures. At higher temperatures, MgO x is completely transformed into MgO. Magnesium hydroxide and oxide heated at different temperatures were studied using the TEM, XRD, IR, PCS, TG-DTA, nitrogen and argon adsorption methods. The electronic structure of MgO and Mg4O3 was studied using the ab initio quantum chemical method with periodic conditions. According to TEM images, the morphology of particles changing from Mg(OH)2 laminae to aggregates of interpenetrated MgO cubelets and foils depend strongly on the calcination temperature. Significant changes in surface area are observed mainly at 325-470 deg. C on desorption of a major portion of eliminated water corresponding to 28.4 wt.% at its total amount of 30.9 wt.%. Pore size distribution (PSD) is sensitive to treatment conditions and the main PSD peaks shift towards larger pore size with elevating temperature. The characteristics of the surface hydroxyls as well as of the bulk Mg-O bonds depend on heating conditions, as noticeable changes are observed in the XRD patterns and the IR spectra of the samples undergoing the mentioned transformation of phase Mg(OH)2→ MgO x→ MgO

  9. Pollution and Prevention of Pb during Cement Calcination

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Emission pollution and prevention measures of Pb during cement calcination were discussed. The content of Pb and the variation of composition were explored by means of atomic absorption spectroscopy (AAS) and X-ray diffraction. The results show that a number of Pb emits during cement calcination, F and C1 promote the emission of Pb, and Pb is enriched in kiln dust. The smaller the particle of kiln dust, the higher the content of Pb. When utilizing the raw materials with a high content of Pb, a more efficient dust collector should be used and the kiln dust should be used as the addition of cement. Pb in clinker is enriched in the intermediate phase. The reduction of silica modulus is useful to increase the solidification content of Pb in clinker. The solidification content of Pb in calcium sulphoaluminate mineral is higher than that in calcium aluminate mineral.

  10. Microstructural changes in porous hematite nanoparticles upon calcination

    DEFF Research Database (Denmark)

    Johnsen, Rune; Knudsen, Kenneth D.; Molenbroek, Alfons M.

    2011-01-01

    This combined study using small-angle neutron scattering (SANS), X-ray powder diffraction (XRPD), transmission electron microscopy (TEM) and adsorption isotherm techniques demonstrates radical changes in the microstructure of porous hematite (-Fe2O3) nanoparticles upon calcination in air. TEM...... images of the as-synthesized hematite sample show that it consists of subrounded nanoparticles [50 (8)–61 (11) nm in average minimum and maximum diameters] with an apparent porous structure of nanosized pores/ channels or cracks. SANS data confirm the presence of two characteristic sizes, one originating...... from the particle size and the other from the pore/void structure. Furthermore, the TEM images show that the particle sizes are nearly unaffected by calcination at 623 K, whereas their pore/void structure changes radically to an apparently pitted or spongy microstructure with cavities or/and voids. The...

  11. KINETICS OF SORPTION OF FLUORIDE ON CALCINED MAGNESITE IN BATCH

    DEFF Research Database (Denmark)

    Singano, J. J.; Mashauri, D. A.; Mtalo, F. W.;

    1997-01-01

    on first-order reaction with respect to the concentration of fluoride. The rate constant is directly proportional to the dosage. The model takes into accounts the lag time observed. The kinetical model can be described for any given dosage and initial fluoride concentration in the water. The reaction...... rate parameter, K, varies however slightly for different initial concentrations of fluoride in the water and different dosage of calcined magnesia. These relationships are described separately by two linear equations. It is discussed that the observed lag time is due to the fact that magnesia cannot......A series of sorption of fluoride on calcined magnesite are obtained from thermostatic pH-chemostat and jar test experiments. The fluoride removal is observed not to start instantly, as normal, but after a lag time of up to ½ an hour of contact time. A model for sorption kinetics is developed, based...

  12. Isotopic Variability of Mercury in Ore, Mine-Waste Calcine, and Leachates of Mine-Waste Calcine from Areas Mined for Mercury

    OpenAIRE

    Stetson, Sarah J.; Gray, John E.; Wanty, Richard B.; Macalady, Donald L.

    2009-01-01

    The isotopic composition of mercury (Hg) was determined in cinnabar ore, mine-waste calcine (retorted ore), and leachates obtained from water leaching experiments of calcine from two large Hg mining districts in the U.S. This study is the first to report significant mass-dependent Hg isotopic fractionation between cinnabar ore and resultant calcine. Data indicate that δ202Hg values relative to NIST 3133 of calcine (up to 1.52‰) in the Terlingua district, Texas, are as much as 3.24‰ heavier th...

  13. Leaching properties and chemical compositions of calcines produced at the Idaho Chemical Processing Plant

    International Nuclear Information System (INIS)

    No significant chemical differences were determined between retrieved and fresh calcine based on chemical and spectrochemical analyses. Little can be derived from the amounts of the radioisotopes present in the retrieved calcine samples other than the ratios of strontium-90 to cesium-137 are typical of aged fission product. The variations in concentrations of radionuclides within the composite samples of each bin also reflect the differences in compositions of waste solutions calcined. In general the leaching characteristics of both calcines by distilled water are similar. In both materials the radionuclides of cesium and strontium were selectively leached at significant rates, although cesium leached much more completely from the alumina calcine than from the zirconia calcine. Cesium and strontium are probably contained in both calcines as nitrate salts and also as fluoride salts in zirconia calcine, all of which are at least slightly soluble in water. Radionuclides of cerium, ruthenium, and plutonium in both calcines were highly resistant to leaching and leached at rates similar to or less than those of the matrix elements. These elements exist as polyvalent metal ions in the waste solutions before calcination and they probably form insoluble oxides and fluorides in the calcine. The relatively slow leaching of nitrate ion from zirconia calcine and radiocesium from both calcines suggests that the calcine matrix in some manner prevents complete or immediate contact of the soluble ions with water. Whether radiostrontium forms slightly fluoride salts or forms nitrate salts which are protected in the same manner as radiocesium is unknown. Nevertheless, selective leaching of cesium and strontim is retarded in some manner by the calcine matrix

  14. Apatite formation on calcined kaolin-white Portland cement geopolymer

    OpenAIRE

    Pangdaeng, S.; Sata, V.; Aguiar, J. L. Barroso de; Torgal, Fernando Pacheco; Chindaprasirt, P.

    2015-01-01

    In this study, calcined kaolin–white Portland cement geopolymerwas investigated for use as biomaterial. Sodiumhydroxide and sodium silicate were used as activators. In vitro test was performed with simulated body fluid (SBF) for bioactivity characterization. The formation of hydroxyapatite bio-layer on the 28-day soaked samples surface was tested using SEM, EDS and XRD analyses. The results showed that the morphology of hydroxyapatite was affected by the source material composition, alkali co...

  15. Calcining process emission screening test for polychlorinated dibenzodioxins

    International Nuclear Information System (INIS)

    Since 1963, the Idaho Chemical Processing Plant (ICPP) at the Idaho National Engineering Laboratory has been using fluidized-bed technology to convert high-level radioactive liquid waste into a granular solid for interim storage before eventual long-term storage. The calcining process uses kerosene, oxygen, air and a cooling jacket to maintain the temperature of the fluidized bed at approximately 400 C. The solids are moved to storage bins and the combustion gases and fine particles are swept from the bed to an atmospheric protection system. This atmospheric protection system includes a cyclone to collect larger particles; a nitric acid scrubber to cool gases and collect small particles; a condenser to reduce water content; silica gel beds to adsorb volatile ruthenium, water, and hydrocarbons; and a series of high efficiency particulate air (HEPA) filters to collect minute particles. The calcination process solidifies waste solutions containing molar levels of acid, nitrate, fluoride, zirconium, aluminum, iron, boron, and cadmium; minor levels (<0.1%) of various fission products and organics; and trace levels (<50 ppm) of chloride and sulfate. Because the process burns kerosene in the presence of other organics and chloride salts; the calciner was considered a potential production source of polychlorinated dibenzo-p-dioxins (PCDD). Therefore, it was necessary to determine if PCDD were being released from the calcination process. Because a gas chromatograph mass spectrometer (GC-MS) and PCDD standards were not available, a screening procedure using two gas chromatographs with electron capture detectors and no PCDD calibration standards was developed

  16. Calcining process emission screening test for polychlorinated dibenzodioxins

    Energy Technology Data Exchange (ETDEWEB)

    Hartenstein, S.D.

    1993-08-01

    Since 1963, the Idaho Chemical Processing Plant (ICPP) at the Idaho National Engineering Laboratory has been using fluidized-bed technology to convert high-level radioactive liquid waste into a granular solid for interim storage before eventual long-term storage. The calcining process uses kerosene, oxygen, air and a cooling jacket to maintain the temperature of the fluidized bed at approximately 400 C. The solids are moved to storage bins and the combustion gases and fine particles are swept from the bed to an atmospheric protection system. This atmospheric protection system includes a cyclone to collect larger particles; a nitric acid scrubber to cool gases and collect small particles; a condenser to reduce water content; silica gel beds to adsorb volatile ruthenium, water, and hydrocarbons; and a series of high efficiency particulate air (HEPA) filters to collect minute particles. The calcination process solidifies waste solutions containing molar levels of acid, nitrate, fluoride, zirconium, aluminum, iron, boron, and cadmium; minor levels (<0.1%) of various fission products and organics; and trace levels (<50 ppm) of chloride and sulfate. Because the process burns kerosene in the presence of other organics and chloride salts; the calciner was considered a potential production source of polychlorinated dibenzo-p-dioxins (PCDD). Therefore, it was necessary to determine if PCDD were being released from the calcination process. Because a gas chromatograph mass spectrometer (GC-MS) and PCDD standards were not available, a screening procedure using two gas chromatographs with electron capture detectors and no PCDD calibration standards was developed.

  17. Mathematical modeling of a rotary hearth coke calciner

    Directory of Open Access Journals (Sweden)

    Hilde C. Meisingset

    1995-10-01

    Full Text Available A mathematical model of a rotary hearth coke calciner is developed. The model is based on first principles including the most important dynamic phenomena. The model is a thermodynamic model involving heat and mass transfer and chemical reactions. Fundamental mass and energy balance equations for the coke phase, the gas phase and the lining are formulated. For the gas phase, a stationary model is used. The equations are solved numerically, and simulated temperature profiles are shown in this paper.

  18. Mathematical modeling of a rotary hearth coke calciner

    OpenAIRE

    Hilde C. Meisingset; Jens G. Balchen

    1995-01-01

    A mathematical model of a rotary hearth coke calciner is developed. The model is based on first principles including the most important dynamic phenomena. The model is a thermodynamic model involving heat and mass transfer and chemical reactions. Fundamental mass and energy balance equations for the coke phase, the gas phase and the lining are formulated. For the gas phase, a stationary model is used. The equations are solved numerically, and simulated temperature profiles are shown in this p...

  19. Synthesis of type A zeolite from calcinated kaolin

    International Nuclear Information System (INIS)

    The mineral production has caused great concern in environmental and industrial scenario due to the effects caused to the environment. The industries of processing kaolin for paper are important economically for the state of Para, but produce huge quantities of tailings, which depend on large areas to be stocked. This material is rich in silico-aluminates can be recycled and used as raw material for other industries. The objective is to synthesize zeolite A at different temperatures of calcination and synthesis. The starting materials and synthesis of zeolite A have been identified and characterized through analysis of X-ray diffraction (DRX) and scanning electron microscopy (MEV). The synthesis process of zeolite A, using as source of silica and the aluminum metakaolin, which was calcined at temperatures of 700 ° C and 800 ° C for 2 hours of landing in a burning furnace type muffle. Observed in relation to the calcination of kaolin as the main phase, the metakaolin. This is just a removal of water from its structure, so we opted for the lower temperature, less energy consumption. The synthesis process of zeolite A, produced good results for the formation of zeolites type A, which were characterized with high purities. (author)

  20. Mathematical modeling of an in-line low-NOx calciner

    DEFF Research Database (Denmark)

    Iliuta, Ion; Dam-Johansen, Kim; Jensen, Lars Skaarup

    2002-01-01

    The reduction of the NOx content in in-line-calciner-type kiln systems can be made by optimization of the primary filing in the rotary kiln and of the secondary firing in the calciner. Because the optimization of calciner offers greater opportunities the mathematical modeling of this reactor is...... very important. A heterogeneous, dynamic mathematical model for an in-line low-NOx calciner based on non-isothermal diffusion reaction models for char combustion and limestone calcination has been developed. The importance of the rate at which preheated combustion air was mixed into the main flow was...

  1. Flash calcination of kaolinite rich clay and impact of process conditions on the quality of the calcines: A way to reduce CO2 footprint from cement industry

    DEFF Research Database (Denmark)

    Gebremariam, Abraham Teklay; Yin, Chungen; Rosendahl, Lasse

    2016-01-01

    Use of properly calcined kaolinite rich clay (i.e., metakaolin) to offset part of CO2-intensive clinkers not only reduces CO2 footprint from cement industry but also improves the performance of concrete. However, calcination under inappropriately high temperatures or long retention times may...

  2. Literature Review of Puo2 Calcination Time and Temperature Data for Specific Surface Area

    International Nuclear Information System (INIS)

    The literature has been reviewed in December 2011 for calcination data of plutonium oxide (PuO2) from plutonium oxalate Pu(C2O4)2 precipitation with respect to the PuO2 specific surface area (SSA). A summary of the literature is presented for what are believed to be the dominant factors influencing SSA, the calcination temperature and time. The PuO2 from Pu(C2O4)2 calcination data from this review has been regressed to better understand the influence of calcination temperature and time on SSA. Based on this literature review data set, calcination temperature has a bigger impact on SSA versus time. However, there is still some variance in this data set that may be reflecting differences in the plutonium oxalate preparation or different calcination techniques. It is evident from this review that additional calcination temperature and time data for PuO2 from Pu(C2O4)2 needs to be collected and evaluated to better define the relationship. The existing data set has a lot of calcination times that are about 2 hours and therefore may be underestimating the impact of heating time on SSA. SRNL recommends that more calcination temperature and time data for PuO2 from Pu(C2O4)2 be collected and this literature review data set be augmented to better refine the relationship between PuO2 SSA and its calcination parameters.

  3. ICPP radioactive liquid and calcine waste technologies evaluation

    International Nuclear Information System (INIS)

    The Department of Energy (DOE) has received spent nuclear fuel (SNF) at the Idaho Chemical Processing Plant (ICPP) for interim storage since 1951 and reprocessing since 1953. Until recently, the major activity of the ICPP has been the reprocessing of SNF to recover fissile uranium; however, changing world events have raised questions concerning the need to recover and recycle this material. In April 1992, DOE chose to discontinue reprocessing SNF for uranium recovery and shifted its focus toward the management and disposition of radioactive wastes accumulated through reprocessing activities. Currently, 1.8 million gallons of radioactive liquid wastes (1.5 million gallons of radioactive sodium-bearing liquid wastes and 0.3 million gallons of high-level liquid waste) and 3,800 cubic meters (m3) of calcine waste are in inventory at the ICPP. Legal drivers and agreements exist obligating the INEL to develop, demonstrate, and implement technologies for safe and environmentally sound treatment and interim storage of radioactive liquid and calcine waste. Candidate treatment processes and waste forms are being evaluated using the Technology Evaluation and Analysis Methodology (TEAM) Model. This process allows decision makers to (1) identify optimum radioactive waste treatment and disposal form alternatives; (2) assess tradeoffs between various optimization criteria; (3) identify uncertainties in performance parameters; and (4) focus development efforts on options that best satisfy stakeholder concerns. The Systems Analysis technology evaluation presented in this document supports the DOE in selecting the most effective radioactive liquid and calcine waste management plan to implement in compliance with established regulations, court orders, and agreements

  4. Consistent Trade Policy Aggregation

    OpenAIRE

    Anderson, James E.

    2008-01-01

    Much empirical work requires the aggregation of policies. This paper provides methods of policy aggregation that are consistent with two common objectives of empirical work. One is to preserve real income. The other is to preserve the real volume of activity in one or more parts of the economy. Trade policy aggregation is an acute example of the aggregation problem with thousands of highly dispersed trade barriers to be aggregated. An application to India shows that the standard atheoretic me...

  5. Consistency in Aggregation

    OpenAIRE

    Ludwig Auer

    2004-01-01

    In empirical economic research, individual prices are often aggregated into average prices of sub-aggregates. Then, these average prices are aggregated to produce the average price of the total aggregate. Often, such two stage procedures help to illuminate the underlying forces driving the overall result. Since price data are usually published as price changes, this two stage aggregation is typically based on some price index formula. In this paper, various screening devices are introduced wh...

  6. Information-aggregation bias

    OpenAIRE

    Goodfriend, Marvin

    1991-01-01

    Aggregation in the presence of data-processing lags distorts the information content of data, violating orthogonality restrictions that hold at the individual level. Though the phenomenon is general, it is illustrated here for the life-cycle-permanent-income model. Cross-section and pooled-panel data induce information-aggregation bias akin to that in aggregate time series. Calculations show that information aggregation can seriously bias tests of the life-cycle model on aggregate time series...

  7. Retrieval System for Calcined Waste for the Idaho Cleanup Project - 12104

    International Nuclear Information System (INIS)

    This paper describes the conceptual approach to retrieve radioactive calcine waste, hereafter called calcine, from stainless steel storage bins contained within concrete vaults. The retrieval system will allow evacuation of the granular solids (calcine) from the storage bins through the use of stationary vacuum nozzles. The nozzles will use air jets for calcine fluidization and will be able to rotate and direct the fluidization or displacement of the calcine within the bin. Each bin will have a single retrieval system installed prior to operation to prevent worker exposure to the high radiation fields. The addition of an articulated camera arm will allow for operations monitoring and will be equipped with contingency tools to aid in calcine removal. Possible challenges (calcine bridging and rat-holing) associated with calcine retrieval and transport, including potential solutions for bin pressurization, calcine fluidization and waste confinement, are also addressed. The Calcine Disposition Project has the responsibility to retrieve, treat, and package HLW calcine. The calcine retrieval system has been designed to incorporate the functions and technical characteristics as established by the retrieval system functional analysis. By adequately implementing the highest ranking technical characteristics into the design of the retrieval system, the system will be able to satisfy the functional requirements. The retrieval system conceptual design provides the means for removing bulk calcine from the bins of the CSSF vaults. Top-down vacuum retrieval coupled with an articulating camera arm will allow for a robust, contained process capable of evacuating bulk calcine from bins and transporting it to the processing facility. The system is designed to fluidize, vacuum, transport and direct the calcine from its current location to the CSSF roof-top transport lines. An articulating camera arm, deployed through an adjacent access riser, will work in conjunction with the

  8. Precipitation of plutonium (III) oxalate and calcination to plutonium oxide

    International Nuclear Information System (INIS)

    The plutonium based fuel fabrication requires the conversion of the plutonium nitrate solution from nuclear fuel reprocessing into pure PuO2. The conversion method based on the precipitation of plutonium (III) oxalate and subsequent calcination has been studied in detail. In this procedure, plutonium (III) oxalate is precipitated, at room temperature, by the slow addition of 1M oxalic acid to the feed solution, containing from 5-100 g/l of plutonium in 1M nitric acid. Before precipitation, the plutonium is adjusted to trivalent state by addition of 1M ascorbic acid in the presence of an oxidation inhibitor such as hydrazine. Finally, the precipitate is calcinated at 700 deg C to obtain PuO2. A flowsheet is proposed in this paper including: a) A study about the conditions to adjust the plutonium valence. b) Solubility data of plutonium (III) oxalate and measurements of plutonium losses to the filtrate and wash solution. c) Characterization of the obtained products. Plutonium (III) oxalate has several potential advantages over similar conversion processes. These include: 1) Formation of small particle sizes powder with good pellets fabrication characteristics. 2) The process is rather insensitive to most process variables, except nitric acid concentration. 3) Ambient temperature operations. 4) The losses of plutonium to the filtrate are less than in other conversion processes. (Author)

  9. Examination of the system fly ash lime calcined gypsum water

    Science.gov (United States)

    Marinkovic, S.; Kostic-Pulek, A.

    2007-05-01

    The feasibility of the utilization of the system fly ash lime calcined gypsum (β-hemihydrate) water (the mass ratio 2:1:2:2.5) for the production of building ceramics was investigated. The system was cured under different conditions, i.e., tap water and ambient air. It was confirmed by X-ray diffraction analysis that three hydration products (gypsum, portlandite and ettringite) were formed in the water-cured system and two (gypsum and portlandite) in the air-cured system. Due to the formation of these products, a compressive strength of 4.01 MPa in the water-cured and 7.83 MPa in air-cured system developed. When the air-cured system was exposed to three alternate heating cooling or three alternate cooling heating cycles, the compressive strength increased (from 7.83 to 9.47 and 10.55 MPa, respectively). The fly ash lime calcined gypsum water systems prepared in this work can be applied for the manufacture of products for internal walls (bricks and blocks).

  10. 46 CFR 148.04-17 - Petroleum coke, calcined, at 130 °F or above.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 5 2010-10-01 2010-10-01 false Petroleum coke, calcined, at 130 °F or above. 148.04-17...-17 Petroleum coke, calcined, at 130 °F or above. (a) The requirements of this part do not apply to bulk shipments of petroleum coke, calcined, on any vessel when the material is less than 130 °F....

  11. 2.2. The kinetics of hydrochloric-acid decomposition of calcined borosilicate ore

    International Nuclear Information System (INIS)

    Present article is devoted to kinetics of hydrochloric-acid decomposition of calcined borosilicate ore. The experimental data of dependence of hydrochloric-acid decomposition of calcined borosilicate ore for boron oxide extraction on temperature (30-95 deg C) and process duration (15-60 min) were considered. It was defined that at temperature increasing the boron oxide extraction increases from 28.9 till 53.2%. The constants of decomposition rate of calcined ore were calculated.

  12. Fluidized-bed calcination of simulated commercial high-level radioactive wastes

    International Nuclear Information System (INIS)

    Work is in progress at the Idaho Chemical Processing Plant to verify process flowsheets for converting simulated commercial high-level liquid wastes to granular solids using the fluidized-bed calcination process. Primary emphasis in the series of runs reported was to define flowsheets for calcining simulated Allied-General Nuclear Services (AGNS) waste and to evaluate product properties significant to calcination, solids storage, or post treatment. Pilot-plant studies using simulated high-level acid wastes representative of those to be produced by Nuclear Fuel Services, Inc. (NFS) are also included. Combined AGNS high-level and intermediate-level waste (0.26 M Na in blend) was successfully calcined when powdered iron was added (to result in a Na/Fe mole ratio of 1.0) to the feed to prevent particle agglomeration due to sodium nitrate. Long-term runs (approximately 100 hours) showed that calcination of the combined waste is practical. Concentrated AGNS waste containing sodium at concentrations less than 0.2 M were calcined successfully; concentrated waste containing 1.13 M Na calcined successfully when powdered iron was added to the feed to suppress sodium nitrate formation. Calcination of dilute AGNS waste by conventional fluid-bed techniques was unsuccessful due to the inability to control bed particle size--both particle size and bed level decreased. Fluid-bed solidification of AGNS dilute waste at conditions in which most of the calcined solids left the calciner vessel with the off-gas was successful. In such a concept, the steady-state composition of the bed material would be approximately 22 wt percent calcined solids deposited on inert particles. Calcination of simulated NFS acid waste indicated that solidification by the fluid-bed process is feasible

  13. 3.2. Decomposition of calcined boron ore by sulfuric acid

    International Nuclear Information System (INIS)

    Present article is devoted to decomposition of calcined boron ore by sulfuric acid. The reaction of calcined danburite ore with sulfuric acid was studied at 30-100 deg C temperature ranges at concentration of H2SO4 from 5 to 70 mass %. The influence of process duration on the rate of extraction of B2O3, Fe2O3 and Al2O3 was studied as well. In order to reach the complete decomposition of oxides from calcined danburite ore the dependence of rate of oxides decomposition on concentration of sulfuric acid was studied. The optimal conditions of sulfuric acid decomposition of calcined danburite ore were proposed.

  14. Feasibility of Carbonaceous Nanomaterial-Assisted Photocatalysts Calcined at Different Temperatures for Indoor Air Applications

    Directory of Open Access Journals (Sweden)

    Wan-Kuen Jo

    2012-01-01

    Full Text Available This study examined the characteristics and photocatalytic activity of multiwall carbon nanotube-assisted TiO2 (MWNT-TiO2 nanocomposites calcined at different temperatures to assess their potential indoor air applications. It was confirmed that the composites calcined at low temperatures (300 and 400°C contained TiO2 nanoparticles bound intimately to the MWNT networks. Meanwhile, almost no MWNTs were observed when the calcination temperature was increased to 500 and 600°C. The MWNT-TiO2 composites calcined at low temperatures showed higher photocatalytic decomposition efficiencies for aromatic hydrocarbons at indoor concentrations than those calcined at high temperatures. The mean efficiencies for benzene, toluene, ethyl benzene, and o-xylene (BTEX by the composite calcined at 300°C were 32, 70, 79, and 79%, respectively, whereas they were 33, 71, 78, and 78% for the composite calcined at 400°C, respectively. In contrast, the efficiencies decreased to close to zero when the calcination temperature was increased to 600°C. Moreover, the MWNT-TiO2 exhibited superior photocatalytic performance for the decomposition efficiencies compared to TiO2 under conventional UV-lamp irradiations. Consequently, these carbonaceous nanomaterial-assisted photocatalysts can be applied effectively to indoor air applications depending upon the calcination temperature.

  15. Platelet aggregation test

    Science.gov (United States)

    The platelet aggregation blood test checks how well platelets , a part of blood, clump together and cause blood to clot. ... Decreased platelet aggregation may be due to: Autoimmune ... Fibrin degradation products Inherited platelet function defects ...

  16. Aggregation in manpower planning

    OpenAIRE

    Wijngaard, J

    1983-01-01

    In manpower planning, as in all other kinds of planning, an important choice is the level of aggregation. The proper level of aggregation depends on the flexibility (mobility) of the personnel. This dependency is investigated in this paper. The manpower system considered is characterized by two dimensions, level and function group. Conditions are derived for aggregate long-term planning (aggregation over function group) combined with one-period disaggregation being optimal.

  17. Aggregating Reputation Feedback

    OpenAIRE

    Garcin, Florent; Faltings, Boi; Jurca, Radu

    2009-01-01

    A fundamental task in reputation systems is to aggregate multiple feedback ratings into a single value that can be used to compare the reputation of different entities. Feedback is most commonly aggregated using the arithmetic mean. However, the mean is quite susceptible to outliers and biases, and thus may not be the most informative aggregate of the reports. We consider three criteria to assess the quality of an aggregator: the informativness, the robustness and the strategyproofness, and a...

  18. Protein aggregation and bioprocessing

    OpenAIRE

    Cromwell, Mary E. M.; Hilario, Eric; Jacobson, Fred

    2006-01-01

    Protein aggregation is a common issue encountered during manufacture of biotherapeutics. It is possible to influence the amount of aggregate produced during the cell culture and purification process by carefully controlling the environment (eg, media components) and implementing appro-priate strategies to minimize the extent of aggregation. Steps to remove aggregates have been successfully used at a manufacturing scale. Care should be taken when developing a process to monitor the compatibili...

  19. Dissolution of two NWCF calcines: Extent of dissolution and characterization of undissolved solids

    International Nuclear Information System (INIS)

    A study was undertaken to determine the dissolution characteristics of two NWCF calcine types. A two-way blended calcine made from 4 parts nonradioactive aluminum nitrate and one part WM-102 was studied to determine the extent of dissolution for aluminum-type calcines. A two-way blend of 3.5 parts fluorinel waste from WM-187 and 1 part sodium waste from WM-185 was used to determine the extent of dissolution for zirconium-type calcines. This study was necessary to develop suitable aqueous separation flowsheets for the partitioning of actinides and fission products from ICPP calcines and to determine the disposition of the resulting undissolved solids (UDS). The dissolution flowsheet developed by Herbst was used to dissolve these two NWCF calcine types. Results show that greater than 95 wt% of aluminum and zirconium calcine types were dissolved after a single batch contact with 5 M HNO3. A characterization of the UDS indicates that the weight percent of TRU elements in the UDS resulting from both calcine type dissolutions increases by approximately an order of magnitude from their concentrations prior to dissolution. Substantial activities of cesium and strontium are also present in the UDS resulting from the dissolution of both calcine types. Multiple TRU, Cs, and Sr analyses of both UDS types show that these solids are relatively homogeneous. From this study, it is estimated that between 63.5 and 635 cubic meters of UDS will be generated from the dissolution of 3800 M3 of calcine. The significant actinide and fission product activities in these UDS will preclude their disposal as low-level waste. If the actinide and fission activity resulting from the UDS is the only considered source in the dissolved calcine solutions, an estimated 99.9 to 99.99 percent of the solids must be removed from this solution for it to meet non-TRU Class A low-level waste

  20. Ignition Dynamic Parameters for Coke in Cement Calciners

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The mathematical ignition model was established and researches of ignition dynamic parameters for coke in some typical coal samples from cement plants was carried out according to circumstances of coal combusted in cement plants.In order to get the ignitioin temperature Tpi of carbon particles more accurately,the temperature rising experimental method was used and the actual heating circumstances for pulverized coal in calciners(in cement plants)were also considered.With this method,the accurate determination of the ignition temperature of coke in coal was achieved,so as to get some ignition dynamic parameters.These research results provide a theoretical basis for investigating coal ignition characteristics more scientifically and more accurately.

  1. STUDY ON HIGH ACID LEACHING REACTIVE CALCINED KAOLIN

    Institute of Scientific and Technical Information of China (English)

    1999-01-01

    Leaching experiments on metakaolin show that the final Al extraction ratio reached in a batch reaction is strikingly influenced by the inferior pore structure geometry of the metakaolin pellets. By calcining kaolin particles adhered in low humidity state,a variety of metakaolin pellet,inside which a large openings structure developed,has been prepared. The structure remarkably benefits leachant ion transference,so,the variety has high acid leaching reactivity,even coarse as the pellets are,its aluminum extracted ratio still has a linear relationship with leaching time,and the leaching kinetics is maintained zero order up to a significant conversion degree. A revised Pellet-Particle Model has been developed to interpret the structure influence on Al extraction ratio.

  2. Calcination system to reduce uranium compounds to UO2 powder

    International Nuclear Information System (INIS)

    Calcination systems to reduce uranium compounds by heating have to be designed in such a way that no oxygen gets into contact with the hot UO2. Up to now, large quantities of H2 were necessary to prevent this. The present invention describes a control system reducing H2 consumption appreciably. To the circulation furnace heated to about 1,0000C, a filling and cooling device is connected via an air-tight seal, this device having the shape of a long body whose hot and dense UO2 filling is moved on and circulated by means of a worm conveyor, the filling being cooled down to about 1000C. Inlet as well as outlet for this device are controlled so that any O2 access can be prevented. (UWI)

  3. Effect of calcination temperature on the photocatalytic reduction and oxidation processes of hydrothermally synthesized titania nanotubes.

    Energy Technology Data Exchange (ETDEWEB)

    Viayan, B.; Dimitrijevic, N. M.; Rajh, T.; Gray, K.; Northwestern Univ.

    2010-08-05

    Titania nanotubes having diameters 8 to 12 nm and lengths of 50-300 nm were prepared using a hydrothermal method. Further, the titania nanotubes were calcined over the temperature range 200-800 C in order to enhance their photocatalytic properties by altering their morphology. The calcined titania nanotubes were characterized by using X-ray diffraction and surface area analysis and their morphological features were studied by scanning and transmission electron microscopy. Nanotubes calcined at 400 C showed the maximum extent of photocatalyitc reduction of carbon dioxide to methane, whereas samples calcined at 600 C produced maximum photocatalytic oxidation of acetaldehyde. Electron paramagnetic resonance (EPR) spectroscopy was used to interrogate the effects of nanotube structure on the charge separation and trapping as a function of calcination temperature. EPR results indicated that undercoordinated titania sites are associated with maximum CO{sub 2} reduction occurring in nanotubes calcined at 400 C. Despite the collapse of the nantube structure to form nanorods and the concomitant loss of surface area, the enhanced charge separation associated with increased crystallinity promoted high rates of oxidation of acetaldehyde in titania materials calcined at 600 C. These results illustrate that calcination temperature allows us to tune the morphological and surface features of the titania nanostructures for particular photocatalytic reactions.

  4. Modeling of in-line low-NOx calciners - a parametric study

    DEFF Research Database (Denmark)

    Iliuta, Ion; Dam-Johansen, Kim; Jensen, Anker;

    2002-01-01

    Simulations with a heterogeneous model of an in-line low-NOx calciner, based on non-isothermal diffusion-reaction models for char combustion and limestone calcination combined with a kinetic model for NO formation and reduction, are reported. The analysis shows that the most important hydrodynamic...

  5. 3.3. The kinetics of sulfuric acid decomposition of calcined borosilicate ore

    International Nuclear Information System (INIS)

    Present article is devoted to kinetics of sulfuric acid decomposition of calcined borosilicate ore. The experimental data of kinetics of extraction of boron oxide from calcined borosilicate ore at sulfuric acid decomposition were obtained at 30-95 deg C temperature ranges and process duration from 15 to 60 minutes.

  6. Test Plan for Radioactive Testing of a Vertical Direct Denitration Calciner

    International Nuclear Information System (INIS)

    A vertical calciner will be used to demonstrate the direct denitration process for converting plutonium-bearing liquors to stable plutonium rich solids. The calciner and some of its associated equipment were previously tested with non-radioactive chemicals to demonstrate operability

  7. Model of fragmentation of limestone particles during thermal shock and calcination in fluidised beds

    Energy Technology Data Exchange (ETDEWEB)

    Saastamoinen, J.; Pikkarainen, T.; Tourunen, A.; Rasanen, M.; Jantti, T. [VTT Technical Research Center, Jyvaskyla (Finland)

    2008-11-15

    Fragmentation of limestone due to thermal shock and calcination in a fluidised bed was studied through experiments and modelling. The time for heating was estimated by model calculations and the time for calcination by measurements. Fragmentation due to thermal shock was carried out by experiments in a CO{sub 2} atmosphere in order to prevent the effect of calcination. It was found to be much less than fragmentation due to calcination. Average particle sizes before and after fragmentation are presented for several types of limestone. The effects of particle size and gas composition on the primary fragmentation were studied through experiments. Increasing the fluidisation velocity increased the tendency to fragment. The evolution of the particle size distribution (PSD) of limestone particles due to thermal shock and during calcination (or simultaneous calcination and sulphation) were calculated using a population balance model. Fragmentation due to thermal shock is treated as an instantaneous process. The fragmentation frequency during calcination is presented as exponentially decaying over time. In addition to the final PSD, this model also predicts the PSD during the calcination process. The fragmentation was practically found to end after 10 min. Furthermore. a population balance method to calculate the particle size distribution and amount of limestone in fluidised beds in dynamic and steady state, when feeding history is known, is presented.

  8. Influence of calcination temperature on the structure and morphology of HAp bioceramics

    International Nuclear Information System (INIS)

    This study aimed to evaluate the influence of calcination temperature on the structure and morphology of samples of hydroxyapatite (HAp) synthesized by the wet method. For hydroxyapatite was used as precursor solutions of calcium hydroxide and phosphoric acid 1M solution of calcium hydroxide was stirred and heated to 80 ° C and then dropwise with a solution of phosphoric acid. After the liquid was evaporated without an oven at 110 ° C and sieved. The sample of PA as synthesized was submitted to calcination at 900 °C and 1100 °C / 2 hours. The samples as synthesized and after calcination were characterized by XRD, XRF, FTIR, SEM. The XRD showed the presence of phase hydroxyapatite for samples without calcining and both calcination temperatures studied. FTIR spectra showed bands group and PO43-, CO32-. Through the SEM micrograph, there is the formation of agglomerates in the form of porous flakes approximately spherical shape. (author)

  9. LITERATURE REVIEW OF PUO2 CALCINATION TIME AND TEMPERATURE DATA FOR SPECIFIC SURFACE AREA

    Energy Technology Data Exchange (ETDEWEB)

    Daniel, G.

    2012-03-06

    The literature has been reviewed in December 2011 for calcination data of plutonium oxide (PuO{sub 2}) from plutonium oxalate Pu(C{sub 2}O{sub 4}){sub 2} precipitation with respect to the PuO{sub 2} specific surface area (SSA). A summary of the literature is presented for what are believed to be the dominant factors influencing SSA, the calcination temperature and time. The PuO{sub 2} from Pu(C{sub 2}O{sub 4}){sub 2} calcination data from this review has been regressed to better understand the influence of calcination temperature and time on SSA. Based on this literature review data set, calcination temperature has a bigger impact on SSA versus time. However, there is still some variance in this data set that may be reflecting differences in the plutonium oxalate preparation or different calcination techniques. It is evident from this review that additional calcination temperature and time data for PuO{sub 2} from Pu(C{sub 2}O{sub 4}){sub 2} needs to be collected and evaluated to better define the relationship. The existing data set has a lot of calcination times that are about 2 hours and therefore may be underestimating the impact of heating time on SSA. SRNL recommends that more calcination temperature and time data for PuO{sub 2} from Pu(C{sub 2}O{sub 4}){sub 2} be collected and this literature review data set be augmented to better refine the relationship between PuO{sub 2} SSA and its calcination parameters.

  10. Comparative evaluation of glasses reprocessing and reversible conditioning of calcinates

    International Nuclear Information System (INIS)

    Fission products and minor actinides separated during the spent fuel reprocessing treatment are industrially vitrified on-line and thus confined inside a glass matrix with admittedly durability properties. In the framework of the feasibility of a reversible conditioning, this document examines first the possible alternative ways of conditioning and storage of calcinates before vitrification, which may simplify the reversibility aspect. Such a conditioning must be compatible with the storage process, with a possible extraction of actinides and long-lived fission products, and with the vitrification process if no extraction is performed. Calcinates are pulverulent and comprise an important soluble fraction, a proportion of nitrates of about 30%, and release a high thermal power (17 kW/m3) combined to a low thermal conductivity (0.1 to 0.15 W.m-1 k-1). Among the different foreseeable solutions (denitration, mixing with another material, with or without compacting, dissolution inside another material..), the dissolution inside a borate seems to be the most acceptable with respect to the safety, feasibility and vitrification aspects. The thermal aspect of the storage remains complex as a specific container is necessary. In a second part, this report analyzes the possibility to re-extract back the long-lived radionuclides from vitrified wastes. The different possible ways to destroy the glass structure and to transfer the fission products and minor actinides in an aqueous solution compatible with an hydrometallurgical separation process are explored. Two processes are foreseeable: a low temperature dissolution process which requires a preliminary crushing and the handling of huge amounts of acids, and a both high and low temperature process which comprises the following steps: melting, fractionation by water tempering, addition of Na2O or sodium tetraborate to make it sensible to hot leaching, separation of fission products and minor actinides, recycling of reagents, and

  11. Provenance for Aggregate Queries

    OpenAIRE

    Yael Amsterdamer; Daniel Deutch; Val Tannen

    2011-01-01

    We study in this paper provenance information for queries with aggregation. Provenance information was studied in the context of various query languages that do not allow for aggregation, and recent work has suggested to capture provenance by annotating the different database tuples with elements of a commutative semiring and propagating the annotations through query evaluation. We show that aggregate queries pose novel challenges rendering this approach inapplicable. Consequently, we propose...

  12. Diffusion in aggregated soil.

    OpenAIRE

    Rappoldt, C.

    1992-01-01

    The structure of an aggregated soil is characterized by the distribution of the distance from an arbitrary point in the soil to the nearest macropore or crack. From this distribution an equivalent model system is derived to which a diffusion model can be more easily applied. The model system consists of spherical, or cylindrical or plane aggregates, which do not represent the individual aggregates of the soil, however. The radii of the spheres, cylinders or plane sheets represent different le...

  13. Synthesis of porous superparamagnetic iron oxides from colloidal nanoparticles: Effect of calcination temperature and atmosphere

    International Nuclear Information System (INIS)

    Nanostructured iron oxides with superparamagnetism were synthesized from colloidal particles of hydrous iron oxide. The synthesis procedure involved preparation of acetone-nanoparticle composite and calcination of the composite in air or nitrogen. The effects of calcination temperature and atmosphere on the properties of the products were investigated. Powder X-ray diffraction, 57Fe Mössbauer spectra, transmission electron microscopy, nitrogen sorption, thermal analysis and vibrating-sample magnetometry were applied to characterize the materials. The products calcined in flowing air are composed of nanoparticles, while those calcined in flowing nitrogen contain nanosheets. The former has larger specific surface areas, whereas the latter has stronger saturation magnetization in external magnetic field. Increasing calcination temperature reduced the specific surface area of the product, whereas enhanced its saturation magnetization. Furthermore, the iron oxides with superparamagnetism showed good affinity to arsenite, and therefore they could be potential adsorbents for arsenic remediation in water. - Highlights: • Nanostructured superparamagnetic iron oxides were synthesized from colloidal nanoparticles. • Calcination in air led to formation of nanoparticles. • Calcination in nitrogen led to formation of nanosheets. • The superparamagnetic materials had high adsorption capabilities for arsenite

  14. Cyclic calcination/carbonation looping of dolomite modified with acetic acid for CO2 capture

    International Nuclear Information System (INIS)

    The dolomite modified with acetic acid solution was proposed as a CO2 sorbent for calcination/carbonation cycles. The carbonation conversions for modified and original dolomites in a twin fixed-bed reactor system with increasing the numbers of cycles were investigated. The carbonation temperature in the range of 630 C-700 C is beneficial to the carbonation reaction of modified dolomite. The carbonation conversion for modified dolomite is significantly higher than that for original sorbent at the same reaction conditions with increasing numbers of reaction cycles. The modified dolomite exhibits a carbonation conversion of 0.6 after 20 cycles, while the unmodified sorbent shows a conversion of 0.26 at the same reaction conditions, which is calcined at 920 C and carbonated at 650 C. At the high calcination temperature over 920 C modified dolomite can maintain much higher conversion than unmodified sorbent. The mean grain size of CaO derived from modified dolomite is smaller than that from original sorbent with increasing numbers of reaction cycles. The calcined modified dolomite possesses greater surface area and pore volume than calcined original sorbent during the multiple cycles. The pore volume and pore area distributions for calcined modified dolomite are also superior to those for calcined unmodified sorbent during the looping cycle. The modified dolomite is proved as a new and promising type of regenerable CO2 sorbent for industrial applications. (author)

  15. Pyrochemical separation of radioactive components from inert materials in ICPP high-level calcined waste

    Energy Technology Data Exchange (ETDEWEB)

    Del Debbio, J.A.; Nelson, L.O.; Todd, T.A.

    1995-05-01

    Since 1963, calcination of aqueous wastes from reprocessing of DOE-owned spent nuclear fuels has resulted in the accumulation of approximately 3800 m{sup 3} of high-level waste (HLW) at the Idaho Chemical Processing Plant (ICPP). The waste is in the form of a granular solid called calcine and is stored on site in stainless steel bins which are encased in concrete. Due to the leachability of {sup 137}Cs and {sup 90}Sr and possibly other radioactive components, the calcine is not suitable for final disposal. Hence, a process to immobilize calcine in glass is being developed. Since radioactive components represent less than 1 wt % of the calcine, separation of actinides and fission products from inert components is being considered to reduce the volume of HLW requiring final disposal. Current estimates indicate that compared to direct vitrification, a volume reduction factor of 10 could result in significant cost savings. Aqueous processes, which involve calcine dissolution in nitric acid followed by separation of actinide and fission products by solvent extraction and ion exchange methods, are being developed. Pyrochemical separation methods, which generate small volumes of aqueous wastes and do not require calcine dissolution, have been evaluated as alternatives to aqueous processes. This report describes three proposed pyrochemical flowsheets and presents the results of experimental studies conducted to evaluate their feasibility. The information presented is a consolidation of three reports, which should be consulted for experimental details.

  16. Microstructural investigation on the effect of calcination temperature on UO3

    International Nuclear Information System (INIS)

    UO3 is one of the most important intermediate products in the nuclear fuel production. UO3 is produced by calcination of ammonium diuranate (ADU) and then subsequently it is reduced to UO2. Depending on the calcination temperature, the stoichiometry of the oxide changes which affects the final recovery in the fuel production. In the present study, microstructural changes in UO3 with the change in calcination temperature were investigated using scanning electron microscope (SEM). ADU slurry was produced by vapour ammonia precipitation of pure uranyl nitrate solution. Precipitate was filtered, dried and calcined in a pre calibrated furnace at different temperatures ranging from 450 deg C to 750 deg C. It was observed that basic microstructure of ADU, which consists of near spherical agglomerate of primary platelets, remains undisturbed during calcination. However, the formation and closure of internal porosities in those primary platelets of UO3 depend substantially on the calcination temperature of ADU. In the present investigation, very high resolution scanning electron micrographs of UO3 particles reveal the details of both internal and external porosities of the primary platelets in the structure. Thus the role of calcination temperature on the chemical reactivity of U-oxide powders and its microstructural evolution were demonstrated

  17. A Real-Time Mathematical Model for the Two-Dimensional Temperature Field of Petroleum Coke Calcination in Vertical Shaft Calciner

    Science.gov (United States)

    Xiao, Jin; Huang, Jindi; Zhong, Qifan; Li, Fachuang; Zhang, Hongliang; Li, Jie

    2016-02-01

    A real-time mathematical model for the two-dimensional temperature field of petroleum coke calcination in vertical shaft calciner was developed based on computational fluid dynamics. In the modeling process, the petroleum coke discharging process was described by the solid viscous flow, the dynamic heat flux boundary condition was adopted to specify the heat transfer between the flue wall and the gas in the flue, and the Arrhenius equation was used to characterize the pyrolysis process of petroleum coke. The model was validated with both measurement data and data from the literature. The effects of discharge rate per pot, volatile content of green coke, and excess air coefficient on the temperature field of the vertical shaft calciner were investigated with the use of the developed model. The following reasonable operating conditions were obtained: the discharge rate per pot should be less than 90 kg/h, the volatile content of green coke should be in the range of 9-11%, and the excess air coefficient should be in the range of 1.10-1.20. In this work, the governing equations were discretized by using the finite volume method, and the discrete linear equations were solved by using sparse matrix package UMFPACK. The model calculating process takes about less than 15 s. Therefore, the model is beneficial in realizing real-time online temperature detection of petroleum coke calcination in a vertical shaft calciner.

  18. Analysis of the attrition of a calcining limestone in a carbonation/calcination pilot plant to capture CO{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    B. Gonzalez; M. Alonso; I. Rodrguez; G. Grasa; J.C. Abanades [CSIC-INCAR Spanish Research Council, Oviedo (Spain)

    2009-07-01

    There is an increasing interest in CO{sub 2} looping cycles that involve the repeatedly calcination and carbonation of the sorbent as a way to capture CO{sub 2} from flue gases during the carbonation step, and the generation of a pure stream of CO{sub 2} in the oxyfired calcination. Attrition of the material in these interconnected fluidized bed reactors is one of the issues of concern. Attrition of limestone derived materials has been studied in fluidized-bed systems by many authors. Many CFB combustors in the world can cope with attrition problems of this material during repeated circulation in their life time in the boiler. In this work we have investigated the phenomenon of the attrition suffered by the limestone used in a system of two interconnected circulating fluidized bed reactors operating in continuous mode as carbonation and calciner reactors. We have found a rapid initial attrition of the limestone during the calcination step followed by a very stable period (during 140 h of added circulation) where particle size changes are negligible. This is consistent with previous observations of attrition in other systems making use of these materials. However, the comparison of attrition constants reveals that our limestone was particularly fragile during the initial calcination and the first few hours of circulation, and a careful choice of limestone according to their attrition properties will be of importance for future carbonate looping systems. 24 refs., 8 figs., 1 tab.

  19. Immobilization of Penicillin G Acylase on Calcined Layered Double Hydroxides

    Institute of Scientific and Technical Information of China (English)

    REN Ling-ling; HE Jing; Evans D. G.; DUAN Xue

    2003-01-01

    A hydrotalcite-like Mg2+/Al3+ layered double hydroxide(LDH) material was prepared by means of a modified coprecipitation method involving a rapid mixing step followed by a separate aging process. LDH calcined at 500 ℃, denoted as CLDH, was characterized by XRD, IR and BET surface area measurements. CLDH has a poor crystalline MgO-like structure with a high surface area and porosity. CLDH was used as a support for the immobilization of penicillin G acylase(PGA). The effect of varying the immobilization conditions, such as pH, contact time and the ratio of enzyme to support, on the activity of the immobilized enzyme in the hydrolysis of penicillin G has been studied. It was found that the activity of the immobilized enzyme decreased slightly with decreasing pH and reached a maximum after a contact time of 24 h. The activity of the immobilized enzyme increased with increasing the ratio of enzyme to support. It was found that the adsorption of PGA inhibited the expected reaction of CLDH with an aqueous medium to regenerate a LDH phase. Its original activity(36%) after 15 cycles of reuse of the immobilized enzyme was retained, but no further loss in the activity was observed.

  20. Microwave calcination for plutonium immobilization and residue stabilization

    International Nuclear Information System (INIS)

    In the late 1980's development was begun on a process using microwave energy to vitrify low level mixed waste sludge and transuranic mixed waste sludge generated in Building 374 at Rocky Flats. This process was shown to produce a dense, highly durable waste form. With the cessation of weapons production at Rocky Flats, the emphasis has changed from treatment of low level and TRU wastes to stabilizaiton of plutonium oxide and residues. This equipment is versatile and can be used as a heat source to calcine, react or vitrify many types of residues and oxides. It has natural economies in that it heats only the material to be treated, significantly reducing cycle times over conventional furnaces. It is inexpensive to operate in that most of the working components remain outside of any necessary contamination enclosure and therefore can easily be maintained. Limited testing has been successfully performed on cerium oxide (as a surrogate for plutonium oxide), surrogate electrorefining salts, surrogate residue sludge and residue ash. Future plans also include tests on ion exchange resins. In an attempt to further the usefullness of this technology, a mobile, self-contained microwave melting system is currently under development and expected to be operational at Rocky Flats Enviromental Technology Site by the 4th quarter of FY96

  1. Attrition of sorbents during fluidized bed calcination and sulphation

    Energy Technology Data Exchange (ETDEWEB)

    Scala, F.; Salatino, P. [Naples Univ. (Italy). Dipartimento di Ingegneria Chimica; Boerefijn, R.; Ghadiri, M. [Surrey Univ., Guildford (United Kingdom). Dept. of Chemical and Process Engineering

    2000-01-24

    The attrition behavior of two different limestones during calcination and sulphation in fluidized beds as been investigated by a combination of experimental techniques. The aim of the study is to shed light on the interactions between sorbent attrition and the change of particle mechanical and morphological properties associated with the progress of chemical reactions. A number of different experimental techniques have been used to characterize breakage mechanisms relevant to particle attrition in different sections of industrial fluidized bed reactors operated at atmospheric pressure. Primary fragmentation and abrasive attrition were characterized in situ by means of experiments carried out in a bench-scale fluidized bed reactor operated batchwise. Fragmentation under high velocity impact conditions was studied ex situ by means of single particle impact tests on pre-conditioned samples at room temperature. Scanning electron and optical microscopy analyses of the particles and EDX mapping of polished particle cross-sections were used to relate topography and internal composition of sorbent particles to the attrition mechanism. (orig.)

  2. PFP vertical calciner shield wall dose rate calculations using MCNP

    International Nuclear Information System (INIS)

    This report yields a neutron shield wall design for a full time occupancy dose rate of 0.25 mrem/h. ORIGEN2 generated gamma ray spectrum and neutron intensity for plutonium. MCNP modeled the calciner glovebox and room for reflection of neutrons off concrete walls and ceiling. Neutron calculations used MCNP in mode n, p to include neutron capture gammas. Photon calculations used MCNP in mode p for gamma rays. Neutron shield with lower 137.16 cm (4.5 feet) of 12.7 cm (5 inch) thick Lucite reg-sign and 0.3175 cm (0.125 inch) stainless steel on both sides, and upper 76.2 cm (2.5 feet) of 10.16 cm (4 inch) thick Lucite reg-sign and 1.905 cm (0.75 inch) thick glass on each side gave a total weighted dose rate of 0.23 mrem/h, fulfilling the design goal. Lucite reg-sign is considered to be equivalent to Plexiglas reg-sign since both are methylmethacrylate polymers

  3. Calcination/dissolution chemistry development Fiscal year 1995

    International Nuclear Information System (INIS)

    The task open-quotes IPC Liaison and Chemistry of Thermal Reconstitutionclose quotes is a $300,000 program that was conducted in Fiscal Year (FY) 1995 with U.S. Department of Energy (DOE) Office of Research and Development (EM-53) Efficient Separations and Processing Crosscutting Program supported under technical task plan (TTP) RL4-3-20-04. The principal investigator was Cal Delegard of the Westinghouse Hanford Company (WHC). The task encompassed the following two subtasks related to the chemistry of alkaline Hanford Site tank waste: (1) Technical Liaison with the Institute of Physical Chemistry of the Russian Academy of Science (IPC/RAS) and its research into the chemistry of transuranic elements (TRU) and technetium (Tc) in alkaline media. (2) Laboratory investigation of the chemistry of calcination/dissolution (C/D) (or thermal reconstitution) as an alternative to the present reference Hanford Site tank waste pretreatment flowsheet, Enhanced Sludge Washing (ESW). This report fulfills the milestone for the C/D subtask to open-quotes Provide End-of-Year Report on C/D Laboratory Test Resultsclose quotes due 30 September 1995. A companion report, fulfilling the milestone to provide an end-of-year report on the IPC/RAS liaison, also has been prepared

  4. The Aggregate-Supply/Aggregate-Demand Model

    OpenAIRE

    BARRO, Robert J.

    1994-01-01

    The aggregate-supply/ aggregate-demand (AS-AD) model is popular in textbooks, but has problems with logical consistency. In one interpretation, the Keynesian underpinnings of the AD curve-derived from the IS/LM model with downward price stickiness-conflict with the determination of the price level at the intersection of the AS and AD curves. In another view, the model corresponds to rational-expectations theories in which Keynesian properties are absent. In a third interpretation, the model i...

  5. SYNTHESIS OF SnO2 NANOCRYSTALS BY SOLID STATE REACTION FOLLOWED BY CALCINATION

    Institute of Scientific and Technical Information of China (English)

    Shanmin Gao; Li Pang; Hongwei Che; Xiaoping Zhou

    2004-01-01

    Nanocrystalline SnO2 was synthesized by direct mixing and grinding of SnCl4·5H2O and NaOH at roomtemperature, followed by calcination at different temperatures for different times in air. Product samples were characterized by X-ray diffraction and transmission electron microscope, revealing that the amorphous precursor SnO2 was transformed to crystals at 200 ℃ for 3 h, and that the average particle size increased upon raising the calcining temperature or prolonging the calcining time. The mechanism of the phase transformation of the products is discussed.

  6. Effect of calcination temperature on structural and magnetic properties of nanocrystalline magnesium ferrite powders

    Science.gov (United States)

    Sumangala, T. P.; Mahender, C.; Venkataramani, N.; Prasad, S.

    2013-02-01

    MgFe2O4 powders with nanosize (30 - 100 nm) were synthesized by the solgel auto combustion method. These powders were calcined at various temperatures (300°C, 400°C, 500°C, 600°C, 700°C, 800°C). An increase in particle size was observed as a function of calcination temperature. The appearance of α-Fe2O3 in samples calcined at intermediate temperatures was studied by XRD, Raman spectra and was confirmed using magnetization data.

  7. 5.3. The kinetics of acetic acid decomposition of calcined borosilicate concentrate

    International Nuclear Information System (INIS)

    Present article is devoted to kinetics of acetic acid decomposition of calcined borosilicate concentrate. The experimental data of kinetics of boron oxide extraction from the calcined danburite concentrate at acetic acid decomposition was obtained at 30-90 deg C temperature ranges and 15-60 minutes process duration. It was defined that at temperature increasing the extraction rate of boron oxide from the calcined danburite concentrate significantly increases. The influence of extraction rate of boron oxide on process duration at acetic acid decomposition was studied.

  8. An Aggregation Matrix MATLAB Function

    OpenAIRE

    Caleb Stair

    2013-01-01

    This Technical Document describes the foundations for an aggregation matrix function implemented in MATLAB, including the format and structure of the required aggregation vector used as an argument to the function. The function is passed with the N-dimensional aggregation vector as an argument. The aggregation vector contains N values ranging from 1 to M, each of which is the aggregate index corresponding to the N pre-aggregation indices. The function returns an aggregation matrix with M rows...

  9. DOES CONSISTENT AGGREGATION REALLY MATTER?

    OpenAIRE

    Shumway, C. Richard; Davis, George C.

    2000-01-01

    Consistent aggregation assures that behavioral properties which apply to disaggregate relationships also apply to aggregate relationships. The agricultural economics literature is reviewed which has tested for consistent aggregation or measured statistical bias and/or inferential errors due to aggregation. Tests for aggregation bias and errors of inference are conducted using indices previously tested for consistent aggregation. Failure to reject consistent aggregation in a partition did not ...

  10. DOES CONSISTENT AGGREGATION REALLY MATTER?

    OpenAIRE

    Shumway, C. Richard; Davis, George C.

    2000-01-01

    Consistent aggregation assures that behavioral properties, which apply to disaggregate relationships also, apply to aggregate relationships. The agricultural economics literature is reviewed which has tested for consistent aggregation or measured statistical bias and/or inferential errors due to aggregation. Tests for aggregation bias and errors of inference are conducted using indices previously tested for consistent aggregation. Failure to reject consistent aggregation in a partition did no...

  11. Thermodynamic Modeling of the Chemical Composition of Calcine at the Idaho Nuclear Technology and Engineering Center

    International Nuclear Information System (INIS)

    To send calcine produced at Idaho National Engineering and Environmental Laboratory to the Yucca Mountain Project for disposal, characterization information will be required. To sample calcine from its existing storage location would require extensive personnel exposure. Sufficient analyses of the chemical composition of the calcine would be extremely difficult and very expensive. In support of characterization development, the chemical composition of calcine from Bin 3 of Calcine Solid Storage Facility II was thermodynamic modeled. This calcine was produced in the Waste Calcination Facility during its second processing campaign, operating with indirect heating at 400 C and 0.744 bar (0.734 atm) during processing of aluminum high-level liquid waste (first cycle extraction raffinate from reprocessing aluminum-clad fuels) from tanks WM-180 and -182 from December 27, 1966 through August 26, 1967. The current modeling effort documents the input compositional data (liquid feed and calciner off-gas) for Batches 300 - 620 and a methodology for estimating the calcine chemical composition. The results, along with assumptions and limitations of the thermodynamic calculations, will serve as a basis for benchmarking subsequent calculations. This will be done by comparing the predictions against extensive analytical results that are currently being obtained on representative samples of the modeled calcine. A commercial free-energy minimization program and database, HSC 5.1, was used to perform the thermodynamic calculations. Currently available experimental data and process information on the calcine were used to make judgments about specific phases and compounds to include and eliminate in the thermodynamic calculations. Some off-gas species were eliminated based on kinetics restrictions evidenced by experimental data and other estimates, and some calcine components and off-gas compounds were eliminated as improbable species (unreliable thermodynamic data). The current Yucca

  12. Bovine Calcined Bone for the Repair of Radial Defect in a Rabbit Model

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    In order to investigate the bovine calcined bone's ability of repairing segmental bone defect and seek a new artificial bone substitute material, the bovine calcined bone (450℃,32 h) was implanted into the 10-mm middle radial defect of rabbits with tricalcium phosphate ceramics as the control. By using the methods of histology, radiology and biomechanics their osteogenic ability were measured. It was found that the bovine calcined bone's ability of repairing bone defect was better than that of tricalcium phosphate ceramics. The histological Nilsson′s scores at 3rd, 5th, 9th week after operation were significantly increased (P<0.01). At 12th week after operation the bending strength of radius in experimental group was much higher than that of control group and turned normal. It was suggested that bovine calcined bone is an ideal artificial bone substitute material with good ability of repairing segmental bone defect and some degree of mechanical strength.

  13. Synthesis of Dy2O3 nanoparticles via hydroxide precipitation:effect of calcination temperature

    Institute of Scientific and Technical Information of China (English)

    Bahaa M. Abu-Zied; Abdullah M. Asiri

    2014-01-01

    This work described the preparation of dysprosium oxide, Dy2O3, nanoparticles using the homogeneous precipitation method. Dy3+ions were precipitated using NaOH solution. The obtained product was filtered, dried, and then calcined for 1 h at the temperature range of 300-700 °C in static air. The calcination temperature of the Dy-precursor was chosen based on its decomposi-tion as indicated by the TGA analysis. The crystalline structure and surface morphology of the calcined solids were studied by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM) and X-ray pho-toelectron spectroscopy (XPS). The obtained results revealed that Dy2O3 with crystallites size of 11-21 nm was formed at 500 °C. Such value increased to 25-37 nm for the sample calcined at 700 °C.

  14. Interlock recovery during the drying, calcination and vitrification phase of Am/Cm processing

    International Nuclear Information System (INIS)

    This document summarizes the results of five CIM5 [5-inch Cylindrical Induction Melter] runs designed to demonstrate power interlock recovery methods during the drying, calcination and vitrification phases of the Am/Cm melter cycle

  15. Heat Transfer Characteristics of Calcined Petroleum Coke in Waste Heat Recovery Process

    Directory of Open Access Journals (Sweden)

    Bin Zheng

    2016-01-01

    Full Text Available This paper reports the results of heat transfer characteristics of calcined petroleum coke in waste heat recovery process. The model of heat exchanger was set up. The model has been used to investigate the effects of porosity (0.58 to 0.79, equivalent heat conductivity coefficient (0.9 to 1.1, and equivalent specific heat (0.9 to 1.1. The calculated values of calcined petroleum coke temperature showed good agreement with the corresponding available experimental data. The temperature distribution of calcined petroleum coke, the calcined petroleum coke temperature at heat exchanger outlet, the average heat transfer coefficient, and the heat recovery efficiency were studied. It can also be used in deriving much needed data for heat exchanger designs when employed in industry.

  16. Decomposition of bastnasite and monazite mixed rare earth minerals calcined byalkali liquid

    Institute of Scientific and Technical Information of China (English)

    XU Yanhui; LIU Haijiao; MENG Zhijun; CUI Jianguo; ZHAO Wenyi; LI Liangcai

    2012-01-01

    The process of decomposion of the bastnasite and monazite rare earth concentrates by alkali solutions was investigated.The mixed slurries of the rare earth concentrates and the alkali solutions were calcined at different temperatures in a rotary tubular electric furnace.The effects of calcination temperature on the decomposing ratio of rare earth,the oxidation ratio of cerium,the stripping of fluorine and phosphorous after calcinations,and the adaptability of the process to the mixed rare earth concentrates of different grade were studied.The results showed that the decomposition ratio of rare earth and the oxidation ratio of cerium could reach 95.8% and 93.7%,respectively,while the calcinating temperature was above 300 ℃.

  17. Preparation of orthorhombic Ba2YCu3O7 powder by single-step calcining

    International Nuclear Information System (INIS)

    A single calcination step, solid-state process that provides orthohombic Ba2YCu3O7 powder is described. BaCO3, Y2O3, and CuO are used as precursor materials. The only phase identifiable by x-ray diffraction is the orthorhombic Ba2YCu3O7. The use of a vacuum during the initial stages of the calcining process promotes complete decomposition of the carbonate, and no residual carbonate is observed. An oxygen atmosphere during the later stages of calcining ensures proper oxidation to Ba2YCu3O7. The use of a similar combination vacuum-oxygen calcining schedule should also be beneficial in the preparation of chemically derived powders

  18. Influence of reduction and calcination conditions of UO2 microspheres in its sintering and pressing behaviour

    International Nuclear Information System (INIS)

    This work describes the studies of the Sol-Gel processing conditions of UO2 microspheres which helps to obtain appropriate properties, for pressing and sintering in cylinder shape pellets with the projected sintered density. It was established that the calcination process is critical, leading to formation of microspheres with low (∼2 g/cm3) or high ≥3 g/cm3) apparent density and so impeding the obtention of reproducible pellets with projected density. This variation was attributed to a reducing condition of CO within the calcination process at 900 deg C due to variation of the oxygen partial pressure in the calcination process at 900 deg C due to the variation of the oxygen partial pressure in the calcination of this hypothesis will be main theme of confirmation in a future work. (author)

  19. Kinetics Analysis on Mixing Calcination Process of Fly Ash and Ammonium Sulfate

    Institute of Scientific and Technical Information of China (English)

    Peng Wang; Laishi Li; Dezhou Wei

    2014-01-01

    abstract The further development of the extraction of alumina that is produced in the calcination process of ammonium sulfate mixed with fly ash was limited because of the lack of systematic theoretical study. In order to aggrandize the research of the calcination process, the kinetics and reaction mechanism of the calcinations were studied. The result suggests that there are two stages in the calcination process, and the alumina extraction rate increases swiftly in the initial stage, but slows down increasing in the later stage. The apparent activation energy of the initial and later stages equals to 13.31 and 35.65 kJ·mol-1, respectively. In the initial stage, ammonium sulfate reacts directly with mullite in the fly ash to form ammonium aluminum sulfate, while in the later stage, alumi-num sulfate is formed by the reaction between ammonium aluminum sulfate and ammonium sulfate.

  20. Volatilization of cobalt, technetium, and uranium isotopes from soils through salt amendment and calcination

    International Nuclear Information System (INIS)

    The effects of alkali and alkaline earth metal chloride salts on the decontamination (through volatilization) of radionuclides from clay soils in a calcination process were examined. Calcium chloride was found to decontaminate 60Co-containing soils to a maximum extent of about 65% of 60Co present before treatment by calcination for 8 h at 1000 deg. C with the addition of about 4 milliequivalents (meq) of chloride per gram of soil. Repeated calcination treatments raised the level of decontamination to 80%, but not beyond. Technetium could be removed from clay soils slightly more effectively using a similar salting and calcination process. No decontamination of strontium or uranium soils was found using this process under reducing or oxidizing conditions. The data presented indicate areas in which the presence of chlorides may result in problems in the thermal treatment of soils or similar matrices; however, no viable decontamination process was achieved

  1. Test Plan for Radioactive Testing of a Vertical Direct Denitration Calciner

    International Nuclear Information System (INIS)

    Stored solutions containing plutonium and nitric acid and possibly uranium thorium and minor amounts of other substances will be used for development and demonstration of a vertical calciner direct denitration process for conversion of those to stable storable PuO2 rich solids. Some of those solutions are quite dilute and very impure these require either pretreatment to make them suitable for calciner feed or an alternate stabilization method. Untreated scrap solutions containing some amounts of sulfate phosphate sodium and/or potassium may also be tested for suitability of direct denitration for conversion directly to PuO2-rich solids. A vertical calciner will be used to demonstrate the direct denitration process for converting plutonium-bearing liquors to stable plutonium-rich solids. The calciner and some of its ancillary equipment were previously tested with non-radioactive chemicals to demonstrate operability

  2. The effect of calcination temperature on the crystallinity of TiO 2 nanopowders

    Science.gov (United States)

    Chen, Yung-Fang; Lee, Chi-Young; Yeng, Ming-Yu; Chiu, Hsin-Tien

    2003-01-01

    TiO 2 nanopowders have been prepared using 0.1 M titanium tetraisopropoxide (TTIP) in varied pH aqueous solution containing TMC and NP-204 surfactants. Only the powder acquired from a solution of pH=2 has a regular particle size distribution. Anatase phase powders are obtained by calcination in nitrogen in the 250-500°C temperature range. When calcined at 400°C, the diameter of the nanoparticles is approximately 10 nm with a specific surface area of 106.9 m 2/g. As the calcination temperature is increased, the particle size increases. Rutile phase powders are formed at calcination temperatures above 600°C.

  3. Test Plan for Radioactive Testing of a Vertical Direct Denitration Calciner

    International Nuclear Information System (INIS)

    Stored solutions containing plutonium and nitric acid and possibly uranium thorium and minor amounts of other substances will be used for development and demonstration of a vertical calciner direct denitration process for conversion of those to stable storable PuO2 rich solids. Some of those solutions are quite dilute and very impure these require either pretreatment to make them suitable for calciner feed or an alternate stabilization method. Untreated scrap solutions containing some amounts of sulfate phosphate sodium and/or potassium may also be tested for suitability of direct denitration for conversion directly to PuO2-rich solids. A vertical calciner will be used to demonstrate the direct denitration process for converting plutonium-bearing liquors to stable plutonium rich solids. The calciner and some of its associated equipment were previously tested with non-radioactive chemicals to demonstrate operability

  4. Design criteria for the new waste calcining facility at the Idaho Chemical Processing Plant

    International Nuclear Information System (INIS)

    The New Waste Calcining Facility (NWCF) at the Idaho Chemical Processing Plant (ICPP) is being built to replace the existing fluidized-bed, high-level waste calcining facility (WCF). Performance of the WCF is reviewed, equipment failures in WCF operation are examined, and pilot-plant studies on calciner improvements are given in relation to NWCF design. Design features of the NWCF are given with emphasis on process and equipment improvements. A major feature of the NWCF is the use of remote maintenance facilities for equipment with high maintenance requirements, thereby reducing personnel exposures during maintenance and reducing downtime resulting from plant decontamination. The NWCF will have a design net processing rate of 11.36 m3 of high-level waste per day, and will incorporate in-bed combustion of kerosene for heating the fluidized bed calciner. The off-gas cleaning system will be similar to that for the WCF

  5. Preparation of U3O8 by calcination from ammonium uranyl carbonate in microwave fields: Process optimization

    International Nuclear Information System (INIS)

    Highlights: • The U3O8 was prepared first from ammonium uranyl carbonate using microwave. • A quadratic model was developed to optimize the process conditions. - Abstract: The effects of process conditions on preparation of U3O8 by calcination from ammonium uranyl carbonate in microwave fields were assessed and optimized for maximizing the total uranium as well as calcination temperature, adopting as Central Composite Design (CCD) methodology. The process variables assessed were calcination temperature, calcination duration and mass of sample. A quadratic model relating the process variables and the total amount of uranium and U3O8 was proposed eliminating the insignificant parameters. The optimal calcination conditions were estimated to be a calcination temperature of 942.75 K, calcination duration of 8.78 min, with the corresponding total uranium and U3O8 to be 82.07% and 31.33%, respectively

  6. Pot-Calcination Process for Converting Highly Radioactive Wastes to Solids

    International Nuclear Information System (INIS)

    The pot-calcination process has successfully converted synthetic non-radioactive Purex, TBP-25 (aluminium, HNO3) and Darex (stainless steel, HNO3) wastes to solids in both bench-scale(24 x 4 in diam.) and engineering-scale (82 X 8 in diam.) pots. The process includes feed evaporation, calcination to 900°C in the pot and recycle of the calciner vapour to the evaporator in a closed loop. Vapour from the evaporator is fractionated to produce water for disposal and nitric acid for re-use. The stainless-steel pot would be sealed after being filled and would serve as both the shipping and ultimate containment vessel. The nitrate content of the calcined solids varied between 60 and 500 ppm. Sulphate volatility during calcination of Purex waste was reduced to less than 0.8% by conversion to thermally stable sodium, magnesium, or calcium salts. Ruthenium volatility from the pot was reduced to less than 20% of the feed by the addition of phosphite or nitric oxide gas to the calciner. Steam stripping to avoid excessive acid build-up in the evaporator limited the volatility of ruthenium from the evaporator to approximately 2% of the feed. Addition of up to 1 ml/1 each of monobutyl and dibutyl phosphate to the feed to simulate solvent degradation products reduced the ruthenium volatility to < 1%. The mercury in TBP wastes was completely volatilized during calcination. Control of a 25-1 hold-up continuous evaporator close-coupled to the. engineering-scale pot calciner was demonstrated and a batch evaporation system was developed during 25 experimental tests. Average feed rates for both systems varied between 8 and 30 1/hr. Small-scale equipment (24 x 4 in diam. pots) for studying fission-product volatilities from actual wastes is installed in a hot cell at Oak Ridge National Laboratory. A 20-1/hr pilot plant for calcination of radioactive Purex, Darex, and TBP-25 wastes in 82 x 6-12-in-diam. pots is being designed for installation at the Idaho Chemical Processing Plant

  7. Phenomenological study of the reactions between glass frit and simulated fission products calcine

    International Nuclear Information System (INIS)

    The COGEMA vitrification process is used in France to immobilize High Level Waste in a glass matrix. A phenomenological study was made in order to understand the reactions between simulated calcine and the glass frit at high temperature. At a laboratory scale, investigations conducted by Scanning Electron Microscopy (SEM) allow the observation of mechanisms and kinetics of interaction between calcine and molten glass frit. (authors)

  8. Structure-function relationships of peptides forming the calcin family of ryanodine receptor ligands.

    Science.gov (United States)

    Xiao, Liang; Gurrola, Georgina B; Zhang, Jing; Valdivia, Carmen R; SanMartin, Mario; Zamudio, Fernando Z; Zhang, Liming; Possani, Lourival D; Valdivia, Héctor H

    2016-05-01

    Calcins are a novel family of scorpion peptides that bind with high affinity to ryanodine receptors (RyRs) and increase their activity by inducing subconductance states. Here, we provide a comprehensive analysis of the structure-function relationships of the eight calcins known to date, based on their primary sequence, three-dimensional modeling, and functional effects on skeletal RyRs (RyR1). Primary sequence alignment and evolutionary analysis show high similarity among all calcins (≥78.8% identity). Other common characteristics include an inhibitor cysteine knot (ICK) motif stabilized by three pairs of disulfide bridges and a dipole moment (DM) formed by positively charged residues clustering on one side of the molecule and neutral and negatively charged residues segregating on the opposite side. [(3)H]Ryanodine binding assays, used as an index of the open probability of RyRs, reveal that all eight calcins activate RyR1 dose-dependently with Kd values spanning approximately three orders of magnitude and in the following rank order: opicalcin1 > opicalcin2 > vejocalcin > hemicalcin > imperacalcin > hadrucalcin > maurocalcin > urocalcin. All calcins significantly augment the bell-shaped [Ca(2+)]-[(3)H]ryanodine binding curve with variable effects on the affinity constants for Ca(2+) activation and inactivation. In single channel recordings, calcins induce the appearance of a subconductance state in RyR1 that has a unique fractional value (∼20% to ∼60% of the full conductance state) but bears no relationship to binding affinity, DM, or capacity to stimulate Ca(2+) release. Except for urocalcin, all calcins at 100 nM concentration stimulate Ca(2+) release and deplete Ca(2+) load from skeletal sarcoplasmic reticulum. The natural variation within the calcin family of peptides offers a diversified set of high-affinity ligands with the capacity to modulate RyRs with high dynamic range and potency. PMID:27114612

  9. 3.5. Sulfuric acid decomposition of calcined concentrate of boron raw material

    International Nuclear Information System (INIS)

    Present article is devoted to sulfuric acid decomposition of calcined concentrate of boron raw material. The results of study of influence of firing temperature of danburite were considered. The influence of firing temperature on the rate of extraction of boron and iron oxides was studied. The dependence of extraction rate of boron and iron oxides on process duration and acid dosage was defined. The optimal conditions of sulfuric acid decomposition of preliminary calcined danburite were proposed.

  10. Silicon-Polymer Encapsulation of High-Level Calcine Waste for Transportation or Disposal

    International Nuclear Information System (INIS)

    This report presents the results of an experimental study investigating the potential uses for silicon-polymer encapsulation of High Level Calcine Waste currently stored within the Idaho Nuclear Technology and Engineering Center (INTEC) at the Idaho National Engineering and Environmental Laboratory (INEEL). The study investigated two different applications of silicon polymer encapsulation. One application uses silicon polymer to produce a waste form suitable for disposal at a High Level Radioactive Waste Disposal Facility directly, and the other application encapsulates the calcine material for transportation to an offsite melter for further processing. A simulated waste material from INTEC, called pilot scale calcine, which contained hazardous materials but no radioactive isotopes was used for the study, which was performed at the University of Akron under special arrangement with Orbit Technologies, the originators of the silicon polymer process called Polymer Encapsulation Technology (PET). This document first discusses the PET process, followed by a presentation of past studies involving PET applications to waste problems. Next, the results of an experimental study are presented on encapsulation of the INTEC calcine waste as it applies to transportation or disposal of calcine waste. Results relating to long-term disposal include: (1) a characterization of the pilot calcine waste; (2) Toxicity Characteristic Leaching Procedure (TCLP) testing of an optimum mixture of pilot calcine, polysiloxane and special additives; and, (3) Material Characterization Center testing MCC-1P evaluation of the optimum waste form. Results relating to transportation of the calcine material for a mixture of maximum waste loading include: compressive strength testing, 10-m drop test, melt testing, and a Department of Transportation (DOT) oxidizer test

  11. Fluidized bed calcination experience with simulated commercial high-level nuclear waste

    International Nuclear Information System (INIS)

    Development and testing of a pilot-scale fluidized bed calciner (1-2 MTU/day) are described. Simulated high-level liquid waste compositions representing those most likely to be generated by commercial nuclear fuel reprocessors were calcined prior to conversion to borosilicate glass forms. A new, much improved operating technique, continuous inert-bed operation (CIB), is described. 38 figures, 16 tables

  12. Synthesis and characterization of ZSM-5 and calcined kaolin evaluation using the content of structure-directing; Sintese e caracterizacao da zeolita ZSM-5 utilizando caulim calcinado e avaliacao do teor de direcionador de estrutura

    Energy Technology Data Exchange (ETDEWEB)

    Rodrigues, J.J.; Silva, V.J. da; Rodrigues, M.G.F., E-mail: jocielys@yahoo.com.br [Universidade Federal de Campina Grande (LABNOV/UAEQ/UFCG), PB (Brazil). Unidade Academica de Engenharia Quimica. Lab. de Desenvolvimento de Novos Materiais

    2012-07-01

    This study aims to evaluate the effect of the structure-directing content, tetrapropylammonium bromide, on the structural and morphological characteristics of ZSM-5 zeolite obtained using calcined kaolin as silicon and aluminum. The samples were characterized by XRD, EDX, SEM and Physics Adsorption N{sub 2}. Trough X ray diffraction patterns was possible to observed the formation of the structure of ZSM-5 with intense peaks and well-defined characteristic of crystalline. The micrographs showed that the samples consist of agglomerates and/or aggregates of particles characteristic of the MFI structure typical of ZSM-5 zeolite. And through the adsorption-desorption isotherms physical N2 was possible to observe that the samples show hysteresis type I typical of microporous materials with specific surface areas of 218 and 222 m{sup 2}/g. Therefore, the use of calcined kaolin to obtain ZSM-5 zeolite was effective. (author)

  13. HWMA closure plan for the Waste Calcining Facility at the Idaho National Engineering Laboratory

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1996-05-01

    The Waste Calcining Facility (WCF) calcined and evaporated aqueous wastes generated from the reprocessing of spent nuclear fuel. The calciner operated from 1963 to 1981, primarily processing high level waste from the first cycle of spent fuel extraction. Following the calciner shutdown the evaporator system concentrated high activity aqueous waste from 1983 until 1987. In 1988, US Department of Energy Idaho Operations Office (DOE-ID) requested interim status for the evaporator system, in anticipation of future use of the evaporator system. The evaporator system has not been operated since it received interim status. At the present time, DOE-ID is completing construction on a new evaporator at the New Waste Calcining Facility (NWCF) and the evaporator at the WCF is not needed. The decision to not use the WCF evaporator requires Lockheed Idaho Technologies Company (LITCO) and DOE-ID to close these units. After a detailed evaluation of closure options, LITCO and DOE-ID have determined the safest option is to fill the voids (grout the vessels, cells and waste pile) and close the WCF to meet the requirements applicable to landfills. The WCF will be covered with a concrete cap that will meet the closure standards. In addition, it was decided to apply these closure standards to the calcining system since it is contained within the WCF building. The paper describes the site, waste inventory, closure activities, and post-closure care plans.

  14. ICPP calcined solids storage facility closure study. Volume III: Engineering design files

    International Nuclear Information System (INIS)

    The following information was calculated to support cost estimates and radiation exposure calculations for closure activities at the Calcined Solids Storage Facility (CSSF). Within the estimate, volumes were calculated to determine the required amount of grout to be used during closure activities. The remaining calcine on the bin walls, supports, piping, and floor was also calculated to approximate the remaining residual calcine volumes at different stages of the removal process. The estimates for remaining calcine and vault void volume are higher than what would actually be experienced in the field, but are necessary for bounding purposes. The residual calcine in the bins may be higher than was is experienced in the field as it was assumed that the entire bin volume is full of calcine before removal activities commence. The vault void volumes are higher as the vault roof beam volumes were neglected. The estimations that follow should be considered rough order of magnitude, due to the time constraints as dictated by the project's scope of work. Should more accurate numbers be required, a new analysis would be necessary

  15. ICPP calcined solids storage facility closure study. Volume III: Engineering design files

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1998-02-01

    The following information was calculated to support cost estimates and radiation exposure calculations for closure activities at the Calcined Solids Storage Facility (CSSF). Within the estimate, volumes were calculated to determine the required amount of grout to be used during closure activities. The remaining calcine on the bin walls, supports, piping, and floor was also calculated to approximate the remaining residual calcine volumes at different stages of the removal process. The estimates for remaining calcine and vault void volume are higher than what would actually be experienced in the field, but are necessary for bounding purposes. The residual calcine in the bins may be higher than was is experienced in the field as it was assumed that the entire bin volume is full of calcine before removal activities commence. The vault void volumes are higher as the vault roof beam volumes were neglected. The estimations that follow should be considered rough order of magnitude, due to the time constraints as dictated by the project`s scope of work. Should more accurate numbers be required, a new analysis would be necessary.

  16. Sorption characteristics of fluoride on to magnesium oxide-rich phases calcined at different temperatures.

    Science.gov (United States)

    Sasaki, Keiko; Fukumoto, Naoyuki; Moriyama, Sayo; Hirajima, Tsuyoshi

    2011-07-15

    The effect of calcination temperature during production of magnesium oxide-rich phases from MgCO(3) on the sorption of F(-) ions in the aqueous phase has been investigated. Magnesium oxide-rich phases were formed by calcination at over 873 K for 1h. Higher calcination temperatures produced more crystalline MgO with smaller specific surface area and provided larger values of the total basicity per unit surface area. The higher calcination temperatures lead to slower F(-) removal rate, and lower equilibrium F(-) concentrations, when the equilibrium F(-) concentrations are less than 1 mmol dm(-3). Larger total basicity per unit surface area made the reactivity with F(-) ions in aqueous phase more feasible, resulting in a greater degree of F(-) sorption. For equilibrium F(-) concentrations more than 1 mmol dm(-3), lower calcination temperatures favored the co-precipitation of F(-) with Mg(OH)(2), probably leading to the formation of Mg(OH)(2-x)F(x), and the achievement of larger sorption density. This is the first paper which describes the relationship between the solid base characteristics obtained by CO(2)-TPD for MgO with different calcination temperatures as a function of the reactivity of F(-) sorption in the aqueous phase. PMID:21571430

  17. HWMA closure plan for the Waste Calcining Facility at the Idaho National Engineering Laboratory

    International Nuclear Information System (INIS)

    The Waste Calcining Facility (WCF) calcined and evaporated aqueous wastes generated from the reprocessing of spent nuclear fuel. The calciner operated from 1963 to 1981, primarily processing high level waste from the first cycle of spent fuel extraction. Following the calciner shutdown the evaporator system concentrated high activity aqueous waste from 1983 until 1987. In 1988, US Department of Energy Idaho Operations Office (DOE-ID) requested interim status for the evaporator system, in anticipation of future use of the evaporator system. The evaporator system has not been operated since it received interim status. At the present time, DOE-ID is completing construction on a new evaporator at the New Waste Calcining Facility (NWCF) and the evaporator at the WCF is not needed. The decision to not use the WCF evaporator requires Lockheed Idaho Technologies Company (LITCO) and DOE-ID to close these units. After a detailed evaluation of closure options, LITCO and DOE-ID have determined the safest option is to fill the voids (grout the vessels, cells and waste pile) and close the WCF to meet the requirements applicable to landfills. The WCF will be covered with a concrete cap that will meet the closure standards. In addition, it was decided to apply these closure standards to the calcining system since it is contained within the WCF building. The paper describes the site, waste inventory, closure activities, and post-closure care plans

  18. Effects of rapid calcination on properties of calcium-based sorbents

    International Nuclear Information System (INIS)

    The calcination process may influence subsequent fragmentation, sintering and swelling when CaO derived from limestone acts as a CO2 or SO2-sorbent in combustion, gasification and reforming. Sorbent properties are affected by CO2 partial pressure, total pressure, temperature, heating rate, impurities and sample size. In this study, the effect of calcination heating rate was investigated based on an electrically heated platinum foil. The effects of heating rate (up to 800 C/s), calcination temperature (700-950 C), particle size (90-180 μm) and sweep gas velocity were investigated. Higher initial heating rates led to lower extents of limestone calcination, but the extents of carbonation of the resulting CaO were similar to each other. Calcium utilization declined markedly during carbonation or sulphation of CaO after calcination by rapid heating. Experimental results show that carbonation and calcium utilization were most effective for carbonation temperatures between 503 and 607 C. Increasing the extent of calcination is not the best way to improve overall calcium utilization due to the vast increase in energy consumption. (author)

  19. The leaching of base minerals from the calcines produced by the roasting of pyrite concentrates

    International Nuclear Information System (INIS)

    A number of gold and uranium plants in South Africa concentrate the pyrite in the ore residue by flotation and roast the concentrate for the production of sulphuric acid. The calcine produced, which is predominantly hematite, is generally subjected to cyanidation for the recovery of gold and silver. The calcines often contain economically significant quantities of copper, nickel , cobalt and uranium. Prior treatment of the calcine for the recovery of these metals would be desirable in terms of the value of the products. Several processes for the leaching of the base metals from plant calcines have been investigated, and an important general conclusion is that an adequate recovery of the base metals requires that a large proportion of the iron should also be extracted. This observation led to a more extensive investigation of the kinetics of leaching of various iron oxides. The application of electrochemical theory and techniques resulted in a fuller understanding of the various factors that govern the rate of leaching of iron oxides. As a result of this fundamental work, alternative treatment schemes that should yield more efficient extraction from calcines were suggested. Several of these possibilities were investigated, and the most promising were found to require reducing conditions during the leach, or prior partial reduction of the calcine to magnetite or wustite

  20. Charged Dust Aggregate Interactions

    Science.gov (United States)

    Matthews, Lorin; Hyde, Truell

    2015-11-01

    A proper understanding of the behavior of dust particle aggregates immersed in a complex plasma first requires a knowledge of the basic properties of the system. Among the most important of these are the net electrostatic charge and higher multipole moments on the dust aggregate as well as the manner in which the aggregate interacts with the local electrostatic fields. The formation of elongated, fractal-like aggregates levitating in the sheath electric field of a weakly ionized RF generated plasma discharge has recently been observed experimentally. The resulting data has shown that as aggregates approach one another, they can both accelerate and rotate. At equilibrium, aggregates are observed to levitate with regular spacing, rotating about their long axis aligned parallel to the sheath electric field. Since gas drag tends to slow any such rotation, energy must be constantly fed into the system in order to sustain it. A numerical model designed to analyze this motion provides both the electrostatic charge and higher multipole moments of the aggregate while including the forces due to thermophoresis, neutral gas drag, and the ion wakefield. This model will be used to investigate the ambient conditions leading to the observed interactions. This research is funded by NSF Grant 1414523.

  1. Aggregated Computational Toxicology Online Resource

    Data.gov (United States)

    U.S. Environmental Protection Agency — Aggregated Computational Toxicology Online Resource (AcTOR) is EPA's online aggregator of all the public sources of chemical toxicity data. ACToR aggregates data...

  2. Calcination, Reduction and Sintering of ADU Spheres for HTGR Fuel

    International Nuclear Information System (INIS)

    of spheres is then formed by the dispersed in air and ammonia gases atmosphere. The gelation of polymer was induced at the surface of the droplets in this step. The surfaces of these liquid droplets are slightly solidified by reaction of ammonia gas and uranyl ion into the droplets. Spherical droplets are converted to aged-ADU gels in NH4OH solution. Then, many steps, such as the ageing and drying of ADU gel, the calcining to UO3, the sintering to UO2, were progressed continuously

  3. Protein Colloidal Aggregation Project

    Science.gov (United States)

    Oliva-Buisson, Yvette J. (Compiler)

    2014-01-01

    To investigate the pathways and kinetics of protein aggregation to allow accurate predictive modeling of the process and evaluation of potential inhibitors to prevalent diseases including cataract formation, chronic traumatic encephalopathy, Alzheimer's Disease, Parkinson's Disease and others.

  4. Platelet activation and aggregation

    DEFF Research Database (Denmark)

    Jensen, Maria Sander; Larsen, O H; Christiansen, Kirsten; Fenger-Eriksen, C; Ingerslev, J; Sørensen, Benny

    2013-01-01

    This study introduces a new laboratory model of whole blood platelet aggregation stimulated by endogenously generated thrombin, and explores this aspect in haemophilia A in which impaired thrombin generation is a major hallmark. The method was established to measure platelet aggregation initiated...... by tissue factor evaluated by means of impedance aggregometry. Citrated whole blood from healthy volunteers and haemophilia A patients with the addition of inhibitors of the contact pathway and fibrin polymerization was evaluated. In healthy persons, a second wave of platelet aggregation was found to...... coincide with the thrombin burst and to be abolished by thrombin inhibitors. In this system, platelet aggregation in severe haemophilia A (n = 10) was found to be significantly decreased as compared with healthy individuals (912 ± 294 vs. 1917 ± 793 AU × min, P = 0.003), most probably due to the weak level...

  5. Recycled aggregates concrete: aggregate and mix properties

    Directory of Open Access Journals (Sweden)

    González-Fonteboa, B.

    2005-09-01

    Full Text Available This study of structural concrete made with recycled concrete aggregate focuses on two issues: 1. The characterization of such aggregate on the Spanish market. This involved conducting standard tests to determine density, water absorption, grading, shape, flakiness and hardness. The results obtained show that, despite the considerable differences with respect to density and water absorption between these and natural aggregates, on the whole recycled aggregate is apt for use in concrete production. 2. Testing to determine the values of basic concrete properties: mix design parameters were established for structural concrete in non-aggressive environments. These parameters were used to produce conventional concrete, and then adjusted to manufacture recycled concrete aggregate (RCA concrete, in which 50% of the coarse aggregate was replaced by the recycled material. Tests were conducted to determine the physical (density of the fresh and hardened material, water absorption and mechanical (compressive strength, splitting tensile strength and modulus of elasticity properties. The results showed that, from the standpoint of its physical and mechanical properties, concrete in which RCA accounted for 50% of the coarse aggregate compared favourably to conventional concrete.

    Se aborda el estudio de hormigones estructurales fabricados con áridos reciclados procedentes de hormigón, incidiéndose en dos aspectos: 1. Caracterización de tales áridos, procedentes del mercado español. Para ello se llevan a cabo ensayos de densidad, absorción, granulometría, coeficiente de forma, índice de lajas y dureza. Los resultados obtenidos han puesto de manifiesto que, a pesar de que existen diferencias notables (sobre todo en cuanto a densidad y absorción con los áridos naturales, las características de los áridos hacen posible la fabricación de hormigones. 2. Ensayos sobre propiedades básicas de los hormigones: se establecen parámetros de dosificaci

  6. Design and performance of a full-scale spray calciner for nonradioactive high-level-waste-vitrification studies

    International Nuclear Information System (INIS)

    In the spray calcination process, liquid waste is spray-dried in a heated-wall spray dryer (termed a spray calciner), and then it may be combined in solid form with a glass-forming frit. This mixture is then melted in a continuous ceramic melter or in an in-can melter. Several sizes of spray calciners have been tested at PNL- laboratory scale, pilot scale and full scale. Summarized here is the experience gained during the operation of PNL's full-scale spray calciner, which has solidified approx. 38,000 L of simulated acid wastes and approx. 352,000 L of simulated neutralized wastes in 1830 h of processing time. Operating principles, operating experience, design aspects, and system descriptions of a full-scale spray calciner are discussed. Individual test run summaries are given in Appendix A. Appendices B and C are studies made by Bechtel Inc., under contract by PNL. These studies concern, respectively, feed systems for the spray calciner process and a spray calciner vibration analysis. Appendix D is a detailed structural analysis made at PNL of the spray calciner. These appendices are included in the report to provide a complete description of the spray calciner and to include all major studies made concerning PNL's full-scale spray calciner

  7. Design and performance of a full-scale spray calciner for nonradioactive high-level-waste-vitrification studies

    Energy Technology Data Exchange (ETDEWEB)

    Miller, F.A.

    1981-06-01

    In the spray calcination process, liquid waste is spray-dried in a heated-wall spray dryer (termed a spray calciner), and then it may be combined in solid form with a glass-forming frit. This mixture is then melted in a continuous ceramic melter or in an in-can melter. Several sizes of spray calciners have been tested at PNL- laboratory scale, pilot scale and full scale. Summarized here is the experience gained during the operation of PNL's full-scale spray calciner, which has solidified approx. 38,000 L of simulated acid wastes and approx. 352,000 L of simulated neutralized wastes in 1830 h of processing time. Operating principles, operating experience, design aspects, and system descriptions of a full-scale spray calciner are discussed. Individual test run summaries are given in Appendix A. Appendices B and C are studies made by Bechtel Inc., under contract by PNL. These studies concern, respectively, feed systems for the spray calciner process and a spray calciner vibration analysis. Appendix D is a detailed structural analysis made at PNL of the spray calciner. These appendices are included in the report to provide a complete description of the spray calciner and to include all major studies made concerning PNL's full-scale spray calciner.

  8. Coagulation with limited aggregations

    CERN Document Server

    Bertoin, Jean

    2012-01-01

    Smoluchowski's coagulation equations can be used as elementary mathematical models for the formation of polymers. We review here some recent contributions on a variation of this model in which the number of aggregations for each atom is a priori limited. Macroscopic results in the deterministic setting can be explained at the microscopic level by considering a version of stochastic coalescence with limited aggregations, which can be related to the so-called random configuration model of random graph theory.

  9. The Aggregation Dilemma

    OpenAIRE

    Ingmar Schumacher

    2014-01-01

    The results in this paper show that the level of aggregation used in a social welfare func- tion matters significantly for policy analysis. Using climate change as an example, it is shown that, under the mild and widely-accepted assumptions of asymmetric climate change impacts and declining marginal utility, an aggregation dilemma may arise that dwarfs most other policy-relevant aspects in the climate change cost-benefit analysis. Estimates based on the RICE-99 model (Nordhaus and Boyer 2000)...

  10. Glycine reduces platelet aggregation

    OpenAIRE

    Schemmer, Peter; Zhong, Zhi; Galli, Uwe; Wheeler, Michael D.; Xiangli, Li; Bradford, Blair U.; Conzelmann, Lars O.; Forman, Dow; Boyer, José; Thurman, Ronald G

    2012-01-01

    It has been demonstrated that a wide variety of white blood cells and macrophages (i.e. Kupffer cells, alveolar and peritoneal macrophages and neutrophils) contain glycine-gated chloride channels. Binding of glycine on the receptor stimulates Cl− influx causing membrane hyperpolarization that prevents agonist-induced influx of calcium. Since platelet-aggregation is calcium-dependent, this study was designed to test the hypothesis that glycine would inhibit platelet aggregation. Rats were fed ...

  11. Effects of Coke Calcination Level on Pore Structure in Carbon Anodes

    Science.gov (United States)

    Fang, Ning; Xue, Jilai; Lang, Guanghui; Bao, Chongai; Gao, Shoulei

    2016-02-01

    Effects of coke calcination levels on pore structure of carbon anodes have been investigated. Bench anodes were prepared by 3 types of cokes with 4 calcination temperatures (800°C, 900°C, 1000°C and 1100°C). The cokes and anodes were characterized using hydrostatic method, air permeability determination, mercury porosimetry, image analysis and confocal microscopy (CSLM). The cokes with different calcination levels are almost the same in LC values (19-20 Å) and real density (1.967-1.985 g/cm3), while the anode containing coke calcined at 900°C has the lowest open porosity and air permeability. Pore size distribution (represented by Anode H sample) can be roughly divided into two ranges: small and medium pores in diameter of 10-400 μm and large pores of 400-580 μm. For the anode containing coke calcined at 800°C, a number of long, narrow pores in the pore size range of 400-580 μm are presented among cokes particles. Formation of these elongated pores may be attributed to coke shrinkages during the anode baking process, which may develop cracking in the anode under cell operations. More small or medium rounded pores with pore size range of 10-400 μm emerge in the anodes with coke calcination temperatures of 900°C, 1000°C and 1100°C, which may be generated due to release of volatiles from the carbon anode during baking. For the anode containing coke calcined at 1100°C, it is found that many rounded pores often closely surround large coke particles, which have potential to form elongated, narrow pores.

  12. Design of a Hot Pilot-Plant Facility for Demonstrating the Pot-Calcination Process

    International Nuclear Information System (INIS)

    A facility has been designed for demonstrating the pot-calcination process with full-level wastes from processing aluminium alloy fuels, from Darex or electrolytic processing of stainless-steel fuels and from Purex processes. This facility will also permit the determination of procedures require a for economical production of low-porosity, relatively non-leachable materials by the addition of suitable reagents to the wastes fed to the calciner. The pot-calcination process, consisting of concentration by evaporation and thermal decomposition in situ in pots which also serve as the final disposal containers, was evolved at the Oak Ridge National Laboratory and developed there in radioactive bench-scale and non-radioactive pilot-plant scale studies. The radioactive demonstration unit will permit identification and solution of operational and control problems connected with the calciner or its closely associated feed preparation and condensate clean-up systems; many of these problems are associated with self-heating and the volatility of fission products. This unit will permit determination of pot loading and density, leachability, melting point, volatile material content, heat release and thermal conductivity of the calcine. Also to be determined are transient calcine temperature distributions, fission-product behaviour during calcination, de-entrainment obtained in the various parts of the system, decontamination achieved on all liquid and gaseous effluent streams, need for venting of stored pots, optimum means of remotely sealing the pots, and methods required for production of a minimum volume of non-condensible off-gas. This facility will employ nominal full-scale pots 8 and 12 inches in diameter and 8 feet long. A unique evaporator design was evolved to permit operation either with close-coupled continuous feed preparation or with bath feed preparation. Provisions were made to circumvent possible explosions due to organic material in feed solutions and other

  13. Determination of the Rate of Formation of Hydroceramic Waste Forms made with INEEL Calcined Wastes

    Energy Technology Data Exchange (ETDEWEB)

    Barry Scheetz; Johnson Olanrewaju

    2001-10-15

    The formulation, synthesis, characterization and hydration kinetics of hydroceramic waste forms designed as potential hosts for existing INEEL calcine high-level wastes have been established as functions of temperature and processing time. Initial experimentations were conducted with several aluminosilicate pozzolanic materials, ranging from fly ash obtained from various power generating coal and other combustion industries to reactive alumina, natural clays and ground bottled glass powders. The final selection criteria were based on the ease of processing, excellent physical properties and chemical durability (low-leaching) determined from the PCT test produced in hydroceramic. The formulation contains vermiculite, Sr(NO32), CsC1, NaOH, thermally altered (calcined natural clay) and INEEL simulated calcine high-level nuclear wastes and 30 weight percent of fluorinel blend calcine and zirconia calcine. Syntheses were carried out at 75-200 degree C at autogeneous water pressure (100% relative humidity) at various time intervals. The resulting monolithic compact products were hard and resisted breaking when dropped from a 5 ft height. Hydroceramic host mixed with fluorinel blend calcine and processed at 75 degree C crumbled into rice hull-side grains or developed scaly flakes. However, the samples equally possessed the same chemical durability as their unbroken counterparts. Phase identification by XRD revealed that hydroceramic host crystallized type zeolite at 75-150 degree C and NaP1 at 175-200 degree C in addition to the presence of quartz phase originating from the clay reactant. Hydroceramic host mixed with either fluorinel blend calcine or zirconia calcine crystallized type A zeolite at 75-95 degree C, formed a mixture of type A zeolite and hydroxysodalite at 125-150 degree C and hydroxysodalite at 175-200 degree C. Quartz, calcium fluoride and zirconia phases from the clay reactant and the two calcine wastes were also detected. The PCT test solution

  14. Preparation of plutonium waste forms with ICPP calcined high-level waste

    International Nuclear Information System (INIS)

    Glass and glass-ceramic forms developed for the immobilization of calcined high-level wastes generated by Idaho Chemical Processing Plant (ICPP) fuel reprocessing activities have been investigated for ability to immobilize plutonium and to simultaneously incorporate calcined waste as an anti-proliferation barrier. Within the forms investigated, crystallization of host phases result in an increased loading of plutonium as well as its incorporation into potentially more durable phases than the glass. The host phases were initially formed and characterized with cerium (Ce+4) as a surrogate for plutonium (Pu+4) and samarium as a neutron absorber for criticality control. Verification of the surrogate testing results were then performed replacing cerium with plutonium. All testing was performed with surrogate calcined high-level waste. The results of these tests indicated that a potentially useful host phase, based on zirconia, can be formed either by devitrification or solid state reaction in the glass studied. This phase incorporates plutonium as well as samarium and the calcined waste becomes part of the matrix. Its ease of formation makes it potentially useful in excess plutonium dispositioning. Other durable host phases for plutonium and samarium, including zirconolite and zircon have been formed from zirconia or alumina calcine through cold press-sintering techniques and hot isostatic pressing. Host phase formation experiments conducted through vitrification or by cold press-sintering techniques are described and the results discussed. Recommendations are given for future work that extends the results of this study

  15. Influence of acid leaching and calcination on iron removal of coal kaolin

    Science.gov (United States)

    Zhu, Pei-wang; Zeng, Wei-qiang; Xu, Xiu-lin; Cheng, Le-ming; Jiang, Xiao; Shi, Zheng-lun

    2014-04-01

    Calcination and acid leaching of coal kaolin were studied to determine an effective and economical preparation method of calcined kaolin. Thermogravimetric-differential thermal analysis (TG-DTA) and X-ray diffraction (XRD) demonstrated that 900°C was the suitable temperature for the calcination. Leaching tests showed that hydrochloric acid was more effective for iron dissolution from raw coal kaolin (RCK), whereas oxalic acid was more effective on iron dissolution from calcined coal kaolin (CCK). The iron dissolution from CCK was 28.78wt%, which is far less effective than the 54.86wt% of RCK under their respective optimal conditions. Through analysis by using Mössbauer spectroscopy, it is detected that nearly all of the structural ferrous ions in RCK were removed by hydrochloric acid. However, iron sites in CCK changed slightly by oxalic acid leaching because nearly all ferrous ions were transformed into ferric species after firing at 900°C. It can be concluded that it is difficult to remove the structural ferric ions and ferric oxides evolved from the structural ferrous ions. Thus, iron removal by acids should be conducted prior to calcination.

  16. Fabrication and characterization of hexagonal boron nitride powder by spray drying and calcining-nitriding technology

    International Nuclear Information System (INIS)

    Hexagonal boron nitride (hBN) powder was fabricated prepared by the spray drying and calcining-nitriding technology. The effects of nitrided temperature on the phases, morphology and particle size distribution of hBN powder, were investigated. The synthesized powders were characterized by X-ray diffraction (XRD), field emission scanning electron microscope (FESEM), Fourier transformed infrared spectrum, ultraviolet-visible (UV-vis) spectrum and photoluminescence (PL) spectrum. UV-vis spectrum revealed that the product had one obvious band gap (4.7 eV) and PL spectrum showed that it had a visible emission at 457 nm (λex=230 nm). FESEM image indicated that the particle size of the synthesized hBN was mainly in the range of 0.5-1.5 μm in diameter, and 50-150 nm in thickness. The high-energy ball-milling process following 900 deg. C calcining process was very helpful to obtain fully crystallized hBN at lower temperature. - Graphical abstract: hBN powder was fabricated prepared by spray drying and calcining-nitriding technology. The results indicated that spray drying and calcining-nitriding technology assisted with high-energy ball-milling process following calcined process was a hopeful way to manufacture hBN powder with high crystallinity in industrial scale

  17. Influence of acid leaching and calcination on iron removal of coal kaolin

    Institute of Scientific and Technical Information of China (English)

    Pei-wang Zhu; Wei-qiang Zeng; Xiu-lin Xu; Le-ming Cheng; Xiao Jiang; Zheng-lun Shi

    2014-01-01

    Calcination and acid leaching of coal kaolin were studied to determine an effective and economical preparation method of calcined kaolin. Thermogravimetric-differential thermal analysis (TG-DTA) and X-ray diffraction (XRD) demonstrated that 900°C was the suitable temperature for the calcination. Leaching tests showed that hydrochloric acid was more effective for iron dissolution from raw coal kaolin (RCK), whereas oxalic acid was more effective on iron dissolution from calcined coal kaolin (CCK). The iron dissolution from CCK was 28.78wt%, which is far less effective than the 54.86wt% of RCK under their respective optimal conditions. Through analysis by using Mössbauer spectroscopy, it is detected that nearly all of the structural ferrous ions in RCK were removed by hydrochloric acid. However, iron sites in CCK changed slightly by oxalic acid leaching because nearly all ferrous ions were transformed into ferric species after firing at 900°C. It can be concluded that it is difficult to remove the structural ferric ions and ferric oxides evolved from the structural ferrous ions. Thus, iron removal by acids should be conducted prior to calcination.

  18. Spray Calciner/In-Can Melter high-level waste solidification technical manual

    International Nuclear Information System (INIS)

    This technical manual summarizes process and equipment technology developed at Pacific Northwest Laboratory over the last 20 years for vitrification of high-level liquid waste by the Spray Calciner/In-Can Melter process. Pacific Northwest Laboratory experience includes process development and demonstration in laboratory-, pilot-, and full-scale equipment using nonradioactive synthetic wastes. Also, laboratory- and pilot-scale process demonstrations have been conducted using actual high-level radioactive wastes. In the course of process development, more than 26 tonnes of borosilicate glass have been produced in 75 canisters. Four of these canisters contained radioactive waste glass. The associated process and glass chemistry is discussed. Technology areas described include calciner feed treatment and techniques, calcination, vitrification, off-gas treatment, glass containment (the canister), and waste glass chemistry. Areas of optimization and site-specific development that would be needed to adapt this base technology for specific plant application are indicated. A conceptual Spray Calciner/In-Can Melter system design and analyses are provided in the manual to assist prospective users in evaluating the process for plant application, to provide equipment design information, and to supply information for safety analyses and environmental reports. The base (generic) technology for the Spray Calciner/In-Can Melter process has been developed to a point at which it is ready for plant application

  19. Chemistry of proposed calcination/dissolution processing of Hanford Site tank wastes

    International Nuclear Information System (INIS)

    Plans exist to separate radioactive waste stored in underground tanks at the US Department of Energy's Hanford Site in south central Washington State into low-level and high-level fractions, and to immobilize the separate fractions in high-integrity vitrified forms for long-term disposal. Calcination with water dissolution has been proposed as a possible treatment for achieving low/high-level separation. Chemistry development activities conducted since 1992 with simulated and genuine tank waste show that calcination/dissolution destroys organic carbon and converts nitrate and nitrite to hydroxide and benign offgases. The process also dissolves significant quantities of bulk chemicals (aluminum, chromium, and phosphate), allowing their redistribution from the high-level to the low-level fraction. Present studies of the chemistry of calcination/dissolution processing of genuine wastes, conducted in the period October 1993 to September 1994, show the importance of sodium fluoride phosphate double salt in controlling phosphate dissolution. Peptization of waste solids is of concern if extensive washing occurs. Strongly oxidizing conditions imposed by calcination reactions were found to convert transition metals to soluble anions in the order chromate > manganate > > ferrate. In analogy with manganese behavior, plutonium dissolution, presumably by oxidation to more soluble anionic species, also occurs by calcination/dissolution. Methods to remove plutonium from the product low-level solution stream must be developed

  20. Effect of Calcined Temperature on the Solubility of Trace Elements from Manifanshi

    Institute of Scientific and Technical Information of China (English)

    HONG Hanlie; TIE Liyun; BIAN Qiujuan; ZHOU Yong

    2006-01-01

    A medical stone manifanshi were researched by using polarized light microscopy, X-ray diffraction (XRD), and inductively coupled plasma atomic emission spectrometry (ICP-AES) methods. The XRD pattern of the raw Manifanshi indicates that it is dominantly composed of plagioclase, orthoclase, quartz, and that of the calcined Manifanshi at 1000 ℃ shows that the distortion of crystal structure in both plagioclase and orthoclase takes place at the calcined temperature. The polarized light microscopy observation suggests that the Manifanshi is naturally weathered monzo-granite porphyry. Chemical analyses reveal that the Manifanshi contains a number of healthful trace elements and rare toxic trace elements, therefore, it is a high quality Manifanshi. The solubility of trace elements was determined by measuring the concentration of trace elements from Manifanshi calcined under varying temperature conditions by ICP method, the results suggest that the calcined product at 1000 ℃ shows the ideal result in ionic concentrations and dissolution rate of trace elements in water, which is contributed to the distortion of the crystal structure of feldspar at the calcined temperature.

  1. Spray Calciner/In-Can Melter high-level waste solidification technical manual

    Energy Technology Data Exchange (ETDEWEB)

    Larson, D.E. (ed.)

    1980-09-01

    This technical manual summarizes process and equipment technology developed at Pacific Northwest Laboratory over the last 20 years for vitrification of high-level liquid waste by the Spray Calciner/In-Can Melter process. Pacific Northwest Laboratory experience includes process development and demonstration in laboratory-, pilot-, and full-scale equipment using nonradioactive synthetic wastes. Also, laboratory- and pilot-scale process demonstrations have been conducted using actual high-level radioactive wastes. In the course of process development, more than 26 tonnes of borosilicate glass have been produced in 75 canisters. Four of these canisters contained radioactive waste glass. The associated process and glass chemistry is discussed. Technology areas described include calciner feed treatment and techniques, calcination, vitrification, off-gas treatment, glass containment (the canister), and waste glass chemistry. Areas of optimization and site-specific development that would be needed to adapt this base technology for specific plant application are indicated. A conceptual Spray Calciner/In-Can Melter system design and analyses are provided in the manual to assist prospective users in evaluating the process for plant application, to provide equipment design information, and to supply information for safety analyses and environmental reports. The base (generic) technology for the Spray Calciner/In-Can Melter process has been developed to a point at which it is ready for plant application.

  2. Sustainable Concrete with Recycled Aggregate

    OpenAIRE

    Kara, P

    2012-01-01

    Concretes produced with recycled aggregates are the subject of several papers recently published in the technical literature. Substitution of natural aggregates can be one of possibilities to take care of landfills and increase of CO2 emissions into the atmosphere in Latvia. Recycled aggregate is a valuable resource; value-added consumption of recycled aggregate, as replacement for virgin aggregate in concrete, can yield significant energy and environmental benefits. In present study recycled...

  3. Arrow's Theorem in Judgement Aggregation

    OpenAIRE

    Franz Dietrich; Christian List

    2005-01-01

    In response to recent work on the aggregation of individual judgements on logically connected propositions into collective judgements, it is often asked whether judgement aggregation is a special case of Arrowian preference aggregation. We argue the opposite. After proving a general impossibility theorem, we construct an embedding of preference aggregation into judgement aggregation and prove Arrow's theorem as a corollary of our result. Although we provide a new proof of Arrow's theorem, our...

  4. Absorption Spectra of Astaxanthin Aggregates

    OpenAIRE

    Olsina, Jan; Durchan, Milan; Minofar, Babak; Polivka, Tomas; Mancal, Tomas

    2012-01-01

    Carotenoids in hydrated polar solvents form aggregates characterized by dramatic changes in their absorption spectra with respect to monomers. Here we analyze absorption spectra of aggregates of the carotenoid astaxanthin in hydrated dimethylsulfoxide. Depending on water content, two types of aggregates were produced: H-aggregates with absorption maximum around 390 nm, and J-aggregates with red-shifted absorption band peaking at wavelengths >550 nm. The large shifts with respect to absorption...

  5. Aggregate Oligopoly Games with Entry

    OpenAIRE

    Anderson, Simon P.; Erkal, Nisvan; Piccinin, Daniel

    2013-01-01

    We use cumulative reaction functions to compare long-run market structures in aggregative oligopoly games. We first compile an IO toolkit for aggregative games. We show strong neutrality properties across market structures. The aggregator stays the same, despite changes in the number of firms and their actions. The IIA property of demands (CES and logit) implies that consumer surplus depends on the aggregator alone, and that the Bertrand pricing game is aggregative. We link together the follo...

  6. High-Temperature Release of SO2 from Calcined Cement Raw Materials

    DEFF Research Database (Denmark)

    Nielsen, Anders Rooma; Larsen, Morten B.; Glarborg, Peter;

    2011-01-01

    During combustion of alternative fuels in the material inlet end of cement rotary kilns, local reducing conditions may occur and cause reductive decomposition of sulfates from calcined cement raw materials. Decomposition of sulfates is problematic because it increases the gas-phase SO2...... concentration, which may cause deposit formation in the kiln system. In this study, the release of sulfur from calcined cement raw materials under both oxidizing and reducing conditions is investigated. The investigations include thermodynamic equilibrium calculations in the temperature interval of 800–1500 °C...... conditions was also observed to increase the sulfur release from the calcined raw materials by a factor of 3, from 14 to 48%....

  7. CALCINATION TEMPERATURE EFFECTS ON OPTICAL PROPERTIES OF NANO-POROUS SILICA THIN FILMS

    Directory of Open Access Journals (Sweden)

    Mohammadreza Mojab

    2015-06-01

    Full Text Available Silica nano-porous thin films at various calcination temperatures were deposited on glass substrates with a layer by layer method. The structure, morphology, surface composition, transmittance and reflectance of the films were investigated by X-ray diffraction, field emission scanning electron microscopy, attenuated total reflectance fourier transform infrared spectroscopy and UV-VIS-NIR spectrophotometer, respectively. The results indicated that the transmittance of the films is increased by increasing the calcinations temperatures to 300oC and at higher temperature, it is decreased. The deposition of silica nano-porous film on the glass at the optimum calcination temperature (300oC decreased refractive index of the glass at a wavelength of 550 nm from 1.5 to 1.37.

  8. Removal of hexavalent chromium from aqueous solution by calcined Zn/Al-LDHs.

    Science.gov (United States)

    Yang, Hui-Duo; Zhao, Yun-Peng; Li, Shi-Feng; Fan, Xing; Wei, Xian-Yong; Zong, Zhi-Min

    2016-01-01

    In this study, Zn/Al-layered double hydroxides (Zn/Al-LDHs) were synthesized by a co-precipitation method and characterized with X-ray diffraction, Fourier transform infrared spectroscopy, and scanning electron microscopy. Then the hexavalent chromium Cr(VI) adsorption experiments on calcined Zn/Al-LDHs were carried out to analyze the effects of pH, temperature, adsorption time, initial Cr(VI) concentration and adsorbent dosage on the removal of Cr(VI) from aqueous solutions. The maximum adsorption capacity for Cr(VI) on calcined Zn/Al-LDHs under optimal conditions was found to be over 120 mg/g. The kinetic and isotherm of Cr(VI) adsorption on calcined Zn/Al-LDHs can be described with the pseudo-second-order kinetic model and Langmuir isotherm, respectively. PMID:27387001

  9. Calcination of Fluorinel-sodium waste blends using sugar as a feed additive (formerly WINCO-11879)

    International Nuclear Information System (INIS)

    Methods were studied for using sugar as a feed additive for converting the sodium-bearing wastes stored at the Idaho Chemical Processing Plant into granular, free flowing solids by fluidized-bed calcination at 500 degrees C. All methods studied blended sodium-bearing wastes with Fluorinel wastes but differed in the types of sugar (sucrose or dextrose) that were added to the blend. The most promising sugar additive was determined to be sucrose, since it is converted more completely to inorganic carbon than is dextrose. The effect of the feed aluminum-to-alkali metal mole ratio on calcination of these blends with sugar was also investigated. Increasing the aluminum-to-alkali metal ratio from 0.6 to 1.0 decreased the calcine product-to-fines ratio from 3.0 to 1.0 and the attrition index from 80 to 15%. Further increasing the ratio to 1.25 had no effect

  10. An Assessment of Using Vibrational Compaction of Calcined HLW and LLW in DWPF Canisters

    International Nuclear Information System (INIS)

    Since 1963, the INEL has calcined almost 8 million gallons of liquid mixed waste and liquid high-level waste, converting it to some 1.1 million gallons of dry calcine (about 4275.0 m3), which consists of alumina-and zirconia-based calcine and zirconia-sodium blend calcine. In addition, if all existing and projected future liquid wastes are solidified, approximately 2,000 m3 of additional calcine will be produced primarily from sodium-bearing waste. Calcine is a more desirable material to store than liquid radioactive waste because it reduces volume, is much less corrosive, less chemically reactive, less mobile under most conditions, easier to monitor and more protective of human health and the environment. This paper describes the technical issue involved in the development of a feasible solution for further volume reduction of calcined nuclear waste for transportation and long term storage, using a standard DWPF canister. This will be accomplished by developing a process wherein the canisters are transported into a vibrational machine, for further volume reduction by about 35%. The random compaction experiments show that this volume reduction is achievable. The main goal of this paper is to demonstrate through computer modeling that it is feasible to use volume reduction vibrational machine without developing stress/strain forces that will weaken the canister integrity. Specifically, the paper presents preliminary results of the stress/strain analysis of the DWPF canister as a function of granular calcined height during the compaction and verifying that the integrity of the canister is not compromised. This preliminary study will lead to the development of better technology for safe compactions of nuclear waste that will have significant economical impact on nuclear waste storage and treatment. The preliminary results will guide us to find better solutions to the following questions: 1) What are the optimum locations and directions (vertical versus horizontal or

  11. The History and Future Challenges of Calcined Petroleum Coke Production and Use in Aluminum Smelting

    Science.gov (United States)

    Edwards, Les

    2015-02-01

    Calcined petroleum coke is used for the production of carbon anodes in the Hall-Héroult aluminum smelting process due to a combination of low impurity levels, ready availability, and relatively low cost. This article provides a review of the history and use of calcined petroleum coke for anode production and describes the different calcining technologies used by the industry. The article discusses the impact of changes in crude oil quality and refining economics over the last 10 years as well as the impact on green petroleum coke quality and availability. The industry has adapted well to quality changes in recent times, and the blending of different quality cokes by smelters is becoming increasingly important. The world has a plentiful supply of green petroleum coke, but the next wave of aluminum smelting capacity growth will put further pressure on the supply of the higher quality cokes traditionally favored by the industry.

  12. Effect of calcination temperature on the photocatalytic properties of electrospun TiO2 nanofibers.

    Science.gov (United States)

    Lee, Young-In; Lee, Jong-Sik; Park, Eun-Sil; Jang, Dae-Hwan; Lee, Jae-Eun; Kim, Kahee; Myung, Nosang V; Choa, Yong-Ho

    2014-10-01

    In this study, TiO2 nanofibers with a high aspect ratio and a large specific surface area were synthesized using the electrospinning technique, and the effect of calcination temperature on their crystal structure, diameter, specific surface area and photocatalytic activity was systematically investigated. The electrospun, as-prepared PVP/TTIP nanofibers were several tens of micrometers in length with a diameter of 74 nm. TiO2 nanofibers with an average diameter of 50 nm were prepared after calcination at various temperatures. The calcination temperature significantly influenced the photocatalytic and material properties of TiO2 including grain size and specific surface area. When compared to other nanostructured TiO2 materials, such as commercial TiO2 nanoparticles (P25, Degussa), the TiO2 nanofibers exhibited greater photocatalytic activity for the degradation of acetaldehyde and ammonia. PMID:25942911

  13. Effects of nanosized metallic palladium loading and calcination on characteristics of composite silica

    Institute of Scientific and Technical Information of China (English)

    吴玉程; 吴侠; 李广海; 张立德

    2003-01-01

    In order to investigate the effects of nanosized metallic palladium loading and calcination on the characteristics of composite silica,the silica was prepared by sol-gel technique,leading to an amorphous solid with mesoporosity,and the pore size distribution is narrow,centered at 3-5 nm.The composite silica was formed by impregnating palladium precursor into the porous network with sequel calcination in hydrogen.The results show that the nanosized palladium as guest phase in the composite silica is subjected to the mesoporous structure and calcination,resulting in the changes of optical adsorption that red-shifted to higher wavelength with the palladium loading and the heating temperature.The tailoring of the optical properties can be ascribed to the effect of the nanosized metal particles and interactions occurred between palladium and silica.

  14. Characterisation of sugar cane straw waste as pozzolanic material for construction: Calcining temperature and kinetic parameters

    International Nuclear Information System (INIS)

    This paper reports on the influence of calcining temperature (800 and 1000 deg. C) on the pozzolanic activation of sugar cane straw (SCS). The reaction kinetics of SCS ash-lime mixtures were inferred from physicochemical characteristics (X-ray diffraction patterns and thermogravimetry analysis. The fitting of a kinetic-diffusive model to the experimental data (fixed lime versus time) allowed the computing of the kinetic parameters (reaction rate constant) of the pozzolanic reaction. Results obtained confirm that the sugar cane straw ash (SCSA) calcined at 800 and 1000 deg. C have properties indicative of very high pozzolanic activity. No influence of calcining temperature on the pozzolanic activity was observed. Also, no crystalline compounds during the pozzolanic reaction were identified up to 90 days of reaction. Environmental durability and strength of the consequential mortars remain to be assessed

  15. Aggregation on heterogeneous surface

    Institute of Scientific and Technical Information of China (English)

    Lu Hang-Jun; Wu Feng-Min; Fang Yun-Zhang

    2004-01-01

    Chessboard-like substrates are introduced in this paper, in order to study the diffusion-limited aggregation (DLA)and the motion of poly-atoms on heterogeneous surfaces. The effect of morphology of such substrates upon the cluster aggregation is investigated using the Monte Carlo simulation. It is found that the growth process and the cluster morphology are governed by the energetic topography of the substrates. Our simulation also indicate that the island density and the fractal dimension of the clusters depend strongly on the substrate topography and the activation energy.

  16. Biodiesel production from waste cooking oil using calcined scallop shell as catalyst

    International Nuclear Information System (INIS)

    Highlights: • Calcined scallop shell was used as low-cost and effective catalyst for biodiesel production. • BDF yield from waste cooking oil reached 86% at 65 °C with a catalyst loading amount of 5 wt%. • Calcined scallop shell showed good reusability. • Calcium glyceroxide played an important role on the reusability of calcined scallop shell. • Water in the waste cooking oil had negative effect on the catalytic activity of calcined scallop shell. - Abstract: Transesterification of waste cooking oil (WCO) and methanol by using calcined scallop shell (CSS) as catalyst was carried out in a closed system for biodiesel fuel (BDF) production. It is found that the optimum calcination temperature for the preparation of CSS was 1000 °C. The effects of transesterification temperature, reaction time, methanol/oil molar ratio and catalyst loading amount on the BDF yield were investigated. Compared with the commercial CaO, CSS showed higher catalytic activity and the BDF yield reached 86% at 65 °C with a catalyst loading amount of 5 wt% (WCO basis) and a reaction time of 2 h. The catalyst was reused for 5 cycles whilst the BDF yield decreased 23%. It is found that CaO in CSS was transferred to calcium glyceroxide after the transesterification reaction, and calcium glyceroxide also showed good catalytic activity and reusability. Furthermore, Water content in WCO had negative effect on BDF yield. It is found that BDF yield reduced 15% due to the occurring of saponification when the water content was increased from 0.64% to 2.48%. It is expected that CCS can be used as an alternative and cheap catalyst for the biodiesel production

  17. Mechanism of cadmium biosorption from aqueous solutions using calcined oyster shells.

    Science.gov (United States)

    Alidoust, Darioush; Kawahigashi, Masayuki; Yoshizawa, Shuji; Sumida, Hiroaki; Watanabe, Makiko

    2015-03-01

    The physicochemical properties of oyster shell-derived adsorbents prepared by calcination at different temperatures were characterized by elemental analysis, specific surface area, particle size distribution, X-ray diffraction, and scanning electron microscopy. The pH value in natural oyster shell increased from 9 to 12.7 following calcination above 750 °C. All of the oyster shell-derived adsorbents exhibited a BET surface area that ranged from 1.8 to 64.6 m(2)/g. Clearly, the proportion of particles within the ranges 25-50 μm and 50-100 μm increased after calcination, regardless of calcination temperature. The adsorption equilibrium and kinetics of cadmium (Cd) were investigated, and the mechanisms of sorption discussed. Experimental equilibrium data were fitted to a Langmuir adsorption isotherm model. Most Cd adsorption occurred during the initial hours of contact time, and a pseudo-second-order kinetic model best fitted the adsorption process. Cd sorption profiles indicated an initial, low Cd sorption region (25.25-32.36 mg/g) that was associated with calcination temperatures of up to 650 °C for 2 h, and a second region that contributed to high Cd sorption from 750 °C, with the maximum sorption capacity reaching a value of 1666.67 mg/g at 900 °C. The high Cd-removal capacity of oyster shell-derived adsorbents above 750 °C is attributed to their enhanced specific surface area, their material porosity, the bulk precipitation of Cd hydroxide and otavite on shell fragments, the formation of ettringite as a secondary precipitate, and ion exchange via Ca ions. This study highlights the effectiveness of calcined oyster shells in Cd removal from highly contaminated water and wastewater. PMID:25438117

  18. Incineration of contaminated organic solvents in a fluidized-bed calciner

    International Nuclear Information System (INIS)

    The reprocessing of expended reactor fuels at the Idaho Chemical Processing Plant (ICPP) generates contaminated organic solvents. An evaluation of potential management alternatives shows that several are suitable for management of contaminated solvents containing tri-butyl phosphate (TBP): the solvent could be burned in a commercially-available burner which absorbs the phosphorus on a fluidized-bed of limestone leaving a solid product for burial; the solvent could be burned in a small fluidized-bed calciner which solidifies non-radioactive feed by in-bed combustion of the contaminated solvent. The fluidized-bed absorbs the phosphate forming a solid product for burial; the solvents could be solidified with a gel or sorbant for burial if the reprocessing system were modified to reduce the solvent volume; and the contaminated solvent could be burned in an existing fluidized-bed calciner designed for solidifying high-level aqueous wastes. Burning the solvent in the existing calciner was selected for process verification because it provides an existing burner, off-gas system, and solids transfer and storage system. No additional wastes are generated. A set of four pilot-plant tests verified the absence of adverse effects from the phosphorus in the fuel when calcining simulated ICPP aqueous wastes. Essentially all of the phosphorus remained in the calcined solids with only a neglegible quantity remaining in the scrubbed off-gas. Combustion efficiency was high (93 to 96%). There were no observable adverse effects on solids in the scrubbing system, corrosion rates, or solids flowability (for retrieval). Conclusions of general applicability are: alternative technologies are available for disposal of contaminated solvents, and the use of an existing fuel-using facility, e.g., calciner or incinerator - designed for contaminated wastes will usually be cost effective

  19. ICPP radioactive liquid and calcine waste technologies evaluation final report and recommendation

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1995-04-01

    Using a formalized Systems Engineering approach, the Latched Idaho Technologies Company developed and evaluated numerous alternatives for treating, immobilizing, and disposing of radioactive liquid and calcine wastes at the Idaho Chemical Processing Plant. Based on technical analysis data as of March, 1995, it is recommended that the Department of Energy consider a phased processing approach -- utilizing Radionuclide Partitioning for radioactive liquid and calcine waste treatment, FUETAP Grout for low-activity waste immobilization, and Glass (Vitrification) for high-activity waste immobilization -- as the preferred treatment and immobilization alternative.

  20. ICPP radioactive liquid and calcine waste technologies evaluation final report and recommendation

    International Nuclear Information System (INIS)

    Using a formalized Systems Engineering approach, the Latched Idaho Technologies Company developed and evaluated numerous alternatives for treating, immobilizing, and disposing of radioactive liquid and calcine wastes at the Idaho Chemical Processing Plant. Based on technical analysis data as of March, 1995, it is recommended that the Department of Energy consider a phased processing approach -- utilizing Radionuclide Partitioning for radioactive liquid and calcine waste treatment, FUETAP Grout for low-activity waste immobilization, and Glass (Vitrification) for high-activity waste immobilization -- as the preferred treatment and immobilization alternative

  1. Heat Transfer Characteristics of Calcined Petroleum Coke in Waste Heat Recovery Process

    OpenAIRE

    Bin Zheng; Yongqi Liu; Lichen Zou; Ruiyang Li

    2016-01-01

    This paper reports the results of heat transfer characteristics of calcined petroleum coke in waste heat recovery process. The model of heat exchanger was set up. The model has been used to investigate the effects of porosity (0.58 to 0.79), equivalent heat conductivity coefficient (0.9 to 1.1), and equivalent specific heat (0.9 to 1.1). The calculated values of calcined petroleum coke temperature showed good agreement with the corresponding available experimental data. The temperature distri...

  2. Fuzzy modeling and control of the calcination process in a kiln

    International Nuclear Information System (INIS)

    Calcination kilns are strongly nonlinear, multivariable processes, that only can be modeled with great uncertainty. In order to get a quality product and ensure the process efficiency, the controller must keep a prescribed temperature profile optimizing the fuel consumption. In this paper, a design methodology of a multivariable fuzzy controller for a nickel calcination kiln is presented. The controller structure is a classical one, and uses the Mamdani fuzzy inference system. In simulation results the fuzzy controller exhibits a great robustness in presence of several types of disturbances, and a better performance than the PID in same conditions is observed. (author)

  3. Ethanol Total Oxidation Over Calcined Layered Double Hydroxides Modified with Organic Components

    OpenAIRE

    Kovanda, F.; Zapivovarski Votipka, Z.; Raabová, H.; Jirátová, K. (Květa); Klempa, J. (Jan); Ludvíková, J. (Jana)

    2013-01-01

    Coprecipitation of Co, Mn, and Al nitrates by a solution of Na2CO3 and NaOH in the presence of Pluronic ® P123 has led to layered double hydroxide (LDH) precursors with hydrotalcite-like structure. Their calcination gave spinel-type mixed oxides; the presence of organic template increased both BET and mesopore surface areas of the calcined products. TPR profiles of the samples modified with Pluronic ® P123 exhibited a shift of reduction maxima to lower temperatures, similarly as increasing so...

  4. Remote design criteria and philosophy of the New Waste Calcining Facility

    International Nuclear Information System (INIS)

    A New Waste Calcining Facility is being built at the Idaho Chemical Processing Plant to replace the existing Waste Calcining Facility which was built to demonstrate fluidized-bed solidification of highly radioactive liquid wastes. The new facility will include significant remote features and provisions for effecting major reductions in the annual personnel radiation exposures being experienced at the Idaho Chemical Processing Plant. Past Chemical Processing Plant equipment failure histories and personnel radiation exposure histories are described along with corrective actions being taken in the new facility to reduce exposures and the anticipated results of those actions

  5. Volatilisation of ruthenium in vitrification. Isothermal calcination studies of 'Magnox' and thermal oxide simulates

    International Nuclear Information System (INIS)

    Ru volatilities have been measured for the static, isothermal calcination of ''Magnox'' and Thermal Oxide HAL's (Highly Active Liquors) at temperatures up to 6000C. Model solutions containing Ru, HNO3, and nitrates of important individual cations have also been investigated. Experimental design was primarily based on the requirements of rotary calcination process development. The results have been interpreted in terms of a reaction model involving competition between the simple degradation of Ru(NO) complexes to RuO2 and oxidative decomposition to volatile species (e.g. RuO4). (author)

  6. Behaviour of selected contaminants in spray calciner/in-can melter waste vitrification off-gas

    International Nuclear Information System (INIS)

    Product loss from spray calciner/in-can melter vitrification of high-level wastes was evaluated with respect to volatile, gaseous and particulate materials. Investigations of the off-gases in a non-radioactive system are discussed, including gaseous constituents, particulate size distributions and loadings. Monitoring of gases leaving the off-gas system during spray calcination/in-can melting of radioactive waste gave material concentrations and material forms in the gases. The most significant conclusion drawn from these studies was that particulate loss accounts for a significant portion of the fission products in the off-gas system. (author)

  7. Study of as-synthesized and calcined hydrocalumites as possible antacid agents

    Indian Academy of Sciences (India)

    Carlos F Linares; Freddy Ocanto; Pablo Bretto; Maricela Monsalve

    2014-06-01

    A hydrocalumite-type solid was synthesized by the homogeneous co-precipitation method by using Ca and Al nitrate solutions in a basic medium (NaOH). This solid was calcined at 700 and 900 °C, respectively. Then, solids were characterized by X-ray diffraction, FT–IR spectroscopy and BET surface area measurements. Finally, these solids were tested as antacids by using a synthetic gastric juice. Results showed that calcined samples were able to neutralize the synthetic gastric juice in more extension as an as-synthesized hydrocalumite; however, the last solid showed better conditions as a potential antacid.

  8. Study of structural transformations and phases formation upon calcination of Zn–Ni–Al hydrotalcite nanosheets

    Indian Academy of Sciences (India)

    Zhanshuang Li; Yanchao Song; Jun Wang; Qi Liu; Piaoping Yang; Milin Zhang

    2011-04-01

    In this paper, we describe a general process for the synthesis of highly crystalline Zn–Ni–Al hydrotalcitelike materials. The structure and thermal decomposition of the prepared samples are studied by XRD, FT–IR, TG–DSC, SEM, TEM and N2 adsorption/desorption. The morphology of large-sized, porous and hexagonal platelike Zn–Ni–Al hydrotalcite is affected by calcination temperature. BET specific surface area and pore volume are observed to increase with increase of the calcination temperature up to 700°C followed by a further decrease with increasing temperature.

  9. Talc-silicon glass-ceramic waste forms for immobilization of high- level calcined waste

    International Nuclear Information System (INIS)

    Talc-silicon glass-ceramic waste forms are being evaluated as candidates for immobilization of the high level calcined waste stored onsite at the Idaho Chemical Processing Plant. These glass-ceramic waste forms were prepared by hot isostatically pressing a mixture of simulated nonradioactive high level calcined waste, talc, silicon and aluminum metal additives. The waste forms were characterized for density, chemical durability, and glass and crystalline phase compositions. The results indicate improved density and chemical durability as the silicon content is increased

  10. Preliminary flowsheet for plasma arc calcination of selected Hanford tank waste

    International Nuclear Information System (INIS)

    This preliminary flowsheet document was developed for the Initial Pretreatment Module (IPM). This flowsheet documents the calcination technology that can be used to accomplish the destruction of organics, ferrocyanide, and nitrate/nitrite salts in addition to solubilizing aluminum compounds in selected waste tanks at the Hanford Site. The flow sheet conditions are 76 L/min diluted waste feed rate at 800 degrees C, atmospheric pressure, and 100 millisecond residence time in the calciner. Preliminary flow diagrams, material balances, and energy requirements are presented

  11. EFFECT OF DRYING AND CALCINATION TEMPERATURE ON HYDROCRACKING CATALYST%干燥及焙烧温度对加氢裂化催化剂的影响

    Institute of Scientific and Technical Information of China (English)

    樊宏飞; 孙晓艳; 崔国旗; 蔡天锡

    2012-01-01

    采用浸渍法在不同干燥和焙烧温度下制备一系列WNi型加氢裂化催化剂,采用N2-物理吸附、NH3-TPD、XRD、TPR等手段对催化剂进行表征,并用十二烷为模型化合物考察催化剂的加氢裂化性能.结果表明:随着焙烧温度的升高,催化剂的比表面积略有降低,孔径变大,孔体积变化不大;随着焙烧温度的升高,催化剂的酸量呈先增加后降低的变化趋势,在400℃时达到最大值,当焙烧温度提高到600℃时,金属组分在载体表面发生聚集;加氢裂化催化剂的活性随着焙烧温度的升高呈先增加后降低的变化趋势,峰值出现在焙烧温度为500℃处.说明适宜的焙烧温度有利于提高催化剂的催化性能,当催化剂经过高温焙烧时,会对其活性产生抑制作用.干燥温度由200℃降到120℃时,催化剂的孔体积和孔径提高,比表面积略有降低,酸量基本不变,催化活性提高.%A series of W/Ni-based hydrocracking catalysts dried and calcined under various temperatures was prepared by impregnation method. The prepared catalysts were characterized by means of N2-adsorption,NH3-TPD,XRD and TPR technique; the hydrocracking performance of these catalysts was investigated using dodecane as model compound. The results showed that with the increase of calcination temperature,the specific surface area of the catalyst decreased slightly,pore size increased and pore volume was basically unchanged. The acid amount and hydrocracking activity of the catalyst both showed a tendency to ascend firstly,followed to descend with the increase of calcination temperature,and the peak value for the former and the latter was at 400 ℃ and 500 ℃ respectively. When the calcination temperature reached 600 ℃ ,aggregation of the metal components happened on the surface of the carrier. On the whole,catalyst calcined under suitable temperature could improve its performance,yet high temperature calcination might suppress the activity of

  12. Aggregates, broccoli and cauliflower

    Science.gov (United States)

    Grey, Francois; Kjems, Jørgen K.

    1989-09-01

    Naturally grown structures with fractal characters like broccoli and cauliflower are discussed and compared with DLA-type aggregates. It is suggested that the branching density can be used to characterize the growth process and an experimental method to determine this parameter is proposed.

  13. Diffusion in aggregated soil.

    NARCIS (Netherlands)

    Rappoldt, C.

    1992-01-01

    The structure of an aggregated soil is characterized by the distribution of the distance from an arbitrary point in the soil to the nearest macropore or crack. From this distribution an equivalent model system is derived to which a diffusion model can be more easily applied. The model system consist

  14. Effect of calcination conditions on microstructures and Jc of YBCO films fabricated by TFA-MOD method

    International Nuclear Information System (INIS)

    YBCO films were grown on LaAlO3 substrates by a metal organic deposition using trifluoroacetates (TFA-MOD). In the TFA-MOD method, a starting solution is coated on a substrate firstly, and then the coated film is calcined to form precursor and finally the precursor film is crystallized to form superconducting YBCO film. In this study, the effects of calcination conditions such as temperature on the microstructures and Jc properties of the YBCO films were studied. In the calcination step, spin coating and calcination were repeated three times for obtaining thick film under the maximum temperatures of 400-500 deg. C. The prepared precursor films were crystallized at a constant condition. The Jc values of the films calcined at 500 deg. C after at 400 deg. C x 2 times, 400 deg. C x 3 times and 500 deg. C x 3 times were about 1.49 MA/cm2, 2.52 MA/cm2 and 1.47 MA/cm2, respectively. Jc depended strongly on the calcination temperature. The cross-sectional TEM images showed that the YBCO film calcined at 400 deg. C x 3 times had less pores than the others. Optimization of the calcination temperature was important to suppress the formation of large precipitates in precursor film, resulting in the suppression of the large pores in the YBCO film

  15. Mobile calcination and cementation unit for solidification of concentrated radioactive wastes

    International Nuclear Information System (INIS)

    The equipment consists of three modular parts placed one on top of the other. The bottom module contains a homogenizer of cement mixes and tanks for chemical additives, condensate and wash water. The second module contains an automatic balance for 8 to 100 kg of cement or calcinate and a balance for up to 100 kg of liquid. The top module contains an electrically heated calcinator and wet aerosol filters. The configuration of the unit is given. The overall dimensions of the equipment are 2350x5600x5400 mm, total weight 8000 kg. All exposed components of the solidification unit are manufactured of austenitic steel. The calcination unit was tested for processing calcinate and model concentrates containing H3BO3 at a concentration of 100 g/dm3 and radionuclides 60Co and 137Cs with an activity of 1010 Bq/m3. Portland 400 cement was used for fixation and CaO and Na2co3 were added to eliminate retardation effects. Solidification took 15 to 30 hrs. (E.S.)

  16. Influence of Calcination Temperature on Nano-TiO2 Photocatalyst Synthesized by Gliding Arc Plasma

    Directory of Open Access Journals (Sweden)

    LIU Shi-Xin, LI Xiao-Song, DENG Xiao-Qing, SUN Zhi-Guang, ZHU Ai-Min

    2015-02-01

    Full Text Available TiO2 nanopowders with different morphologies and initial anatase contents (fA were synthesized by gliding arc plasma. X-ray diffraction (XRD, transmission electron microscope (TEM and physisorption instruments were employed to investigate the effects of calcination temperature on phase composition, crystal size, morphology and specific surface area (SBET of the TiO2 nanopowders. Photocatalytic oxidation of methylene blue was utilized to evaluate the activities of calcined TiO2 nanopowders. The results indicate that the anatase-rutile transformation temperature of as-synthesized TiO2 nanopowders is around 650℃, and the anatase-rutile transformation rate depends on the calcination temperature, morphology and the initialfA. With the increase of calcination temperature, the anatase crystal size slightly increases and SBET slightly decreases for spherical particles, while for non-spherical particles, the anatase crystal size increases and SBET decreases rapidly. With the increase of fA, the variation of photocatalytic apparent rate constant (k of TiO2 nanopowder presents three profiles: whenfA is below 70%, k slowly increases; whenfA ranges from 70% to 85%, k rapidly increases; whenfA is beyond 85%, k rapidly decreases.

  17. Synthesis of alumina powder with seeds by Pechini Method using O2 as calcination atmosphere

    International Nuclear Information System (INIS)

    Alumina is a very investigated material due to its excellent refractory characteristics and mechanical properties. Its alpha phase, the most stable one, has a formation temperature of about 1200 ° C. Due to its high temperature of formation, many researches have been trying to reduce it through addition of seeds of alpha phase in chemical processes of synthesis. This work aims to synthesize ultrafine powders of alpha-alumina by the Pechini method with seeding, and using an O2 atmosphere in the pre-calcination (500 ° C) and calcination (1000 ° C and 1100° C) steps. The resulting powders were characterized through X-ray diffractometry, infrared spectroscopy and scanning electron microscopy. The results were compared with samples calcined on ai. It was verified that the presence of oxygen in the calcination atmosphere favored the elimination of residual carbon from the precursor powders, forthcoming from the great amount of organic material used on the synthesis, modifying its morphology and favoring reduction of particle size. (author)

  18. Restart Plan for the Prototype Vertical Denitration Calciner [SD Coversheet has Incorrect Document Number

    Energy Technology Data Exchange (ETDEWEB)

    SUTTER, C.S.

    1999-07-26

    Testing activities on the Prototype Vertical Denitration Calciner at PFP were suspended in January 1997 due to the hold on fissile material handling in the facility. The Restart Plan will govern the transition of the test program from the completion of the activity based startup review; through equipment checkout and surrogate material runs; to resumption of the testing program and transition to unrestricted testing.

  19. Oxidative dehydrogenation of ethylbenzene to styrene over alumina : effect of calcination

    NARCIS (Netherlands)

    Nederlof, Christian; Zarubina, Valeriya; Melian-Cabrera, Ignacio; Heeres, Hero Jan (Eric); Kapteijn, Freek; Makkee, Michiel

    2013-01-01

    Commercially available gamma-Al2O3 was calcined at temperatures between 500 and 1200 degrees C and tested for its performance in the oxidative ethylbenzene dehydrogenation (ODH) over a wide range of industrially-relevant conditions. The original gamma-Al2O3, as well as Z- and alpha-Al2O3, were teste

  20. Effect of sulfuric acid concentration of bentonite and calcination time of pillared bentonite

    Science.gov (United States)

    Mara, Ady; Wijaya, Karna; Trisunaryati, Wega; Mudasir

    2016-04-01

    An activation of natural clay has been developed. Activation was applied by refluxing the natural bentonite in variation of the sulfuric acid concentration and calcination time of pillared bentonite (PLC). Calcination was applied using oven in microwave 2,45 GHz. Determination of acidity was applied by measuring the amount of adsorbed ammonia and pyridine. Morphological, functional groups and chrystanility characterizations were analyzed using SEM, TEM, FTIR and XRD. Porosity was analyzed using SSA. The results showed that the greater of the concentration of sulfuric acid and calcination time was, the greater the acidity of bentonite as well as the pore diameter were. FTIR spectra showed no fundamental changes in the structure of the natural bentonite, SEM, and TEM images were showing an increase in space or field due to pillarization while the XRD patterns showed a shift to a lower peak. Optimization was obtained at a concentration of 2 M of sulfuric acid and calcination time of 20 minutes, keggin ion of 2.2 and suspension of 10 mmol, respectively each amounted to 11.7490 mmol/gram of ammonia and 2.4437 mmol/gram of pyridine with 154.6391 m2/gram for surface area, 0.130470 m3/gram of pore volume and 3.37484 nm of pore diameter.

  1. Effect of Boric Acid on Properties of Calcined Flint Clay-Bauxite Castables

    Institute of Scientific and Technical Information of China (English)

    ZHANG Wei; DAI Wenyong

    2010-01-01

    In order to prolong the working time of calcined flint clay-bauxite castables during construction at high temperature,boric acid was added into the castables.The effect of boric acid on working time and curing cold crushing strength of the castables at 25 ℃ and 35 ℃were investigated.After 24 h curing in mould and another 24 h curing at 110 ℃ after demoulding,the specimens were heat treated at 1 000 ℃,1 300 ℃,and1 500 ℃ for 3 h,respectively.The permanent linear change,bulk density,modulus of rupture,and cold crushing strength were determined.The result shows that there is no need to add boric acid when calcined flint clay-bauxite ca.stables works at 25 ℃ ; when calcined flint clay-bauxite castables works at 35 ℃,boric acid can increase the working time of the castables,but decrease the curing cold crushing strength a little.Adding boric acid into calcined flint clay-bauxite castables doesn' t worsen performance of the castablcs.

  2. Calcined eggshell (CES): An efficient natural catalyst for Knoevenagel condensation under aqueous condition

    Indian Academy of Sciences (India)

    Suresh Patil; Swati D Jadhav; M B Deshmukh

    2013-07-01

    A convenient, eco-friendly and economic method for Knoevenagel condensation of aromatic aldehydes with active methylene compounds using calcined eggshell (CES) as an efficient natural catalyst in aqueous medium has been reported. CES is a new, ecologically safe and inexpensive green catalyst obtained from renewable resources.

  3. 46 CFR 148.04-15 - Petroleum coke, uncalcined; petroleum coke, uncalcined and calcined (mixture).

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 5 2010-10-01 2010-10-01 false Petroleum coke, uncalcined; petroleum coke, uncalcined and calcined (mixture). 148.04-15 Section 148.04-15 Shipping COAST GUARD, DEPARTMENT OF HOMELAND... Requirements for Certain Material § 148.04-15 Petroleum coke, uncalcined; petroleum coke, uncalcined...

  4. The calcination and sulphation behaviour of sorbents in fluidized bed combustion

    Energy Technology Data Exchange (ETDEWEB)

    Haji-Sulaiman, M.Z.; Scaroni, A.W. (Pennsylvania State University, University Park, PA (USA). Combustion Laboratory)

    1991-02-01

    A study was performed on the effects of the CO{sub 2} partial pressure in the calcining gas and sorbent impurities on the structure of calcines produced and on subsequent sulphation behaviour under fluidized bed combustion conditions. It was found that the average pore size and the BET surface area were affected markedly by these two parameters, but their effect on pore volume was not significant. Increasing both parameters increased the average pore size and decreased the surface area as a consequence of sintering. During sulphation the presence of impurities delayed pore closure due to the formation of CaSO{sub 4}. Hence, higher calcium utilization was achieved from the lower purity stones. The results highlight the importance of considering chemical composition in addition to initial physical properties in the selection of sorbents for use during fluidized bed coal combustion, since chemical composition controls, to a large extent, the physical properties developed upon calcination, and the structure of the calcine affects sulphation behaviour. 30 refs., 7 figs., 2 tabs.

  5. Effect of the rate of calcination of kaolin on the properties of metakaolin-based geopolymers

    Directory of Open Access Journals (Sweden)

    B.B. Kenne Diffo

    2015-03-01

    Full Text Available Kaolin samples of the same mass were treated at 700 °C for the same duration of 30 min by varying the rate of calcination (1, 2.5, 5, 10, 15 and 20 °C/min in order to obtain metakaolins which were used to produce geopolymers. Depending on the nature of each type of material, kaolin, metakaolins and geopolymers were characterized using thermal analysis, chemical analysis, XRD, FTIR, particle size distribution, specific surface area, bulk density, setting time and compressive strength. FTIR and XRD analyses showed that metakaolins except at 1 °C/min contained residual kaolinite whose quantity increased with the rate of calcination of kaolin and which influenced the characteristics of geopolymers. Thus as the rate of calcination of kaolin increased, the setting time increased (226 min (rate of 1 °C/min–773 min (rate of 20 °C/min while the compressive strength reduced (49.4 MPa (rate of 1 °C/min–20.8 MPa (rate of 20 °C/min. From the obtained results the production of geopolymers having high compressive strength along with low setting time requires that the calcination of kaolin be carried out at a low rate.

  6. Method and apparatus for evaporating radioactive liquid and calcinating the residue

    International Nuclear Information System (INIS)

    This invention provides an apparatus and a process for evaporating liquid wastes and calcining the residue. The liquid is sprayed against a hollow, rotating heated cylinder within a casing. The dried residue is scraped from the rotating cylinder and released through a valve at the bottom of the casing, while the effluent gas is filtered

  7. Aggregation Algorithms in Heterogeneous Tables

    OpenAIRE

    Titus Felix FURTUNA; Ivan, Ion; Marian DARDALA

    2006-01-01

    The heterogeneous tables are most used in the problem of aggregation. A solution for this problem is to standardize these tables of figures. In this paper, we proposed some methods of aggregation based on the hierarchical algorithms.

  8. Chemical and mineralogical modifications of simplified radioactive waste calcine during heat treatment

    International Nuclear Information System (INIS)

    The microstructural and mineralogical changes associated with heating calcined mixtures of Al(NO3)3⋅9H2O–NaNO3 have been studied. This system is a simplified analogue of high-level radioactive waste calcine, one of the raw materials used in the vitrification process employed for waste management. The decomposition (dehydration and denitration) and formation of secondary crystalline phases have been studied by differential thermal and gravimetric analysis (DTA and TGA), and heat-treated products characterized by X-ray diffraction, Raman spectroscopy, Nuclear Magnetic Resonance (NMR) and Transmission Electron Microscopy (TEM). It is found that pure Al(NO3)3⋅9H2O transforms to amorphous Al2O3 at a temperature of ∼180 °C, well below that of the calcination process (500 °C). This amorphous Al2O3 is highly porous with a high specific surface area, but may in turn convert to denser γ-Al2O3 and α-Al2O3 with increasing temperature. On the other hand, pure NaNO3 remains stable up to ∼880 °C, despite a solid–liquid transition at ∼320 °C. For Al(NO3)3⋅9H2O–NaNO3 mixtures, the products of calcination at 500 °C are found to consist of very fine porous material containing Na, Al and O, in addition to a variable proportion of well-defined crystals consisting of Na, and O. Heating these mixtures to temperatures of up to 1000 °C shows that for the case 80% Al(NO3)3⋅9H2O −20% NaNO3 (weight%) a variety of crystalline sodium aluminates is formed (NaAlO2, NaAl11O17, NaAl6O9.5), while for the 50–50 mixture, only NaAlO2 is found. In large amounts, addition of alumina thus leads to the formation of crystalline phases rich in Al2O3 that are responsible for hardening the calcine as the temperature rises. The kinetics of nitrogen loss from NaNO3 are also found to be influenced by the relative proportion of Al(NO3)3⋅9H2O in the calcine, larger amounts of Al leading to denitration at lower temperature. These results constitute the necessary background for

  9. Chemical and mineralogical modifications of simplified radioactive waste calcine during heat treatment

    Science.gov (United States)

    Monteiro, A.; Schuller, S.; Toplis, M. J.; Podor, R.; Ravaux, J.; Clavier, N.; Brau, H. P.; Charpentier, T.; Angeli, F.; Leterrier, N.

    2014-05-01

    The microstructural and mineralogical changes associated with heating calcined mixtures of Al(NO3)3ṡ9H2O-NaNO3 have been studied. This system is a simplified analogue of high-level radioactive waste calcine, one of the raw materials used in the vitrification process employed for waste management. The decomposition (dehydration and denitration) and formation of secondary crystalline phases have been studied by differential thermal and gravimetric analysis (DTA & TGA), and heat-treated products characterized by X-ray diffraction, Raman spectroscopy, Nuclear Magnetic Resonance (NMR) and Transmission Electron Microscopy (TEM). It is found that pure Al(NO3)3ṡ9H2O transforms to amorphous Al2O3 at a temperature of ∼180 °C, well below that of the calcination process (500 °C). This amorphous Al2O3 is highly porous with a high specific surface area, but may in turn convert to denser γ-Al2O3 and α-Al2O3 with increasing temperature. On the other hand, pure NaNO3 remains stable up to ∼880 °C, despite a solid-liquid transition at ∼320 °C. For Al(NO3)3ṡ9H2O-NaNO3 mixtures, the products of calcination at 500 °C are found to consist of very fine porous material containing Na, Al and O, in addition to a variable proportion of well-defined crystals consisting of Na, and O. Heating these mixtures to temperatures of up to 1000 °C shows that for the case 80% Al(NO3)3ṡ9H2O -20% NaNO3 (weight%) a variety of crystalline sodium aluminates is formed (NaAlO2, NaAl11O17, NaAl6O9.5), while for the 50-50 mixture, only NaAlO2 is found. In large amounts, addition of alumina thus leads to the formation of crystalline phases rich in Al2O3 that are responsible for hardening the calcine as the temperature rises. The kinetics of nitrogen loss from NaNO3 are also found to be influenced by the relative proportion of Al(NO3)3ṡ9H2O in the calcine, larger amounts of Al leading to denitration at lower temperature. These results constitute the necessary background for understanding

  10. Effect of calcination methods on electrochemical performance of NiO used as electrode materials for supercapacitor

    Indian Academy of Sciences (India)

    L Wang; X Y Qin

    2014-05-01

    Ni(OH)2 precursors were prepared via the precipitation transformation method, which was originated from Na2C2O4, NiSO4.6H2O and urea. NiO samples were successfully obtained by calcining Ni(OH)2 precursor with different calcination methods. Some were calcination in a tube furnace under the nitrogen flow and others were calcination in a muffle furnace. The products were well-characterized by thermogravimetric analysis (TGA), X-ray diffraction (XRD) and scanning electron microscopy (SEM). The influence of calcination methods on electrochemical performance of NiO samples were investigated. Moreover, the possible reason was proposed. The charge storage mechanism of NiO positive electrode in aqueous electrolyte was discussed. The electrochemical test showed that the as-prepared NiO prepared in a tube furnace can exhibit a good pseudocapacitance behaviour due to the higher utilization of active material.

  11. Effect of calcination time on NiAl-Al2O3 using gel combustion synthesis method

    Science.gov (United States)

    Afandi, N. F.; Manap, A.; Yusof, S. N. A.; Salim, M. A.; Azim, M. Al.; Othman, S. Z.; Pauzi, N. I. M.; Omar, Nooririnah; Misran, H.

    2015-07-01

    This study was conducted in order to investigate the effect of calcination time on phase and microstructural characteristics of intermetallic matric composite (IMC), NiAl-Al2O3 powder. This powder was synthesized using gel combustion method with octyl alcohol as fuel. Upon completion of the combustion process, the loose powder was calcined at 1050°C for 1, 2 and 4 hours and characterized using XRD, FESEM and TEM. The crystallite size was calculated to be in the range of 29-30 nm. It was found that NiAl-Al2O3 exhibits high crystalline structure after calcination for 4 hours. Furthermore, longer calcination time also cause growth of the particle size. Findings indicate that high crystalline nanostructured NiAl-Al2O3 powder consisting of submicron particles can be successfully produced using gel combustion synthesis with longer calcination time.

  12. ASSESSMENT OF RECYCLED AGGREGATE CONCRETE

    OpenAIRE

    Ahmad Mujahid Ahmad Zaidi

    2009-01-01

    Used of recycled aggregate (RA) in concrete can be described in environmental protection and economical terms. The application of recycled aggregate to use in construction activities have been practice by developed European countries and also of some Asian countries. This paper reports the results of an experimental study on the mechanical properties of recycled aggregate concrete (RAC) as compared to natural aggregate concrete (NAC). The effects of size of RA on compressive strength were dis...

  13. Judgement aggregation and distributed thinking

    OpenAIRE

    Spiekermann, Kai

    2010-01-01

    In recent years, judgement aggregation has emerged as an important area of social choice theory. Judgement aggregation is concerned with aggregating sets of individual judgements over logically connected propositions into a set of collective judgements. It has been shown that even seemingly weak conditions on the aggregation function make it impossible to find functions that produce rational collective judgements from all possible rational individual judgements. This implies...

  14. Actinide partitioning from actual ICPP dissolved zirconium calcine using the TRUEX solvent

    International Nuclear Information System (INIS)

    The TRansUranic EXtraction process (TRUEX), as developed by E.P. Horwitz and coworkers at Argonne National Laboratory (ANL), is being evaluated as a TRU extraction process for Idaho Chemical Processing Plant (ICPP) wastes. A criteria that must be met during this evaluation, is that the aqueous raffinate must be below the 10 nCi/g limit specified in 10 CFR 61.55. A test was performed where the TRUEX solvent (0.2 M octyl(phenyl)-N-N-diisobutyl-carbamoylmethyl-phosphine oxide (CMPO), and 1.4 M tributylphosphate (TBP) in an Isopar-L diluent) was contacted with actual ICPP dissolved zirconium calcine. Two experimental flowsheets were used to determine TRU decontamination factors, and TRU, Zr, Fe, Cr, and Tc extraction, scrub, and strip distribution coefficients. Results from these two flowsheets show that >99.99% of the TRU alpha activity was removed from the acidic feed after three contacts with the TRUEX solvent (fresh solvent being used for each contact). The resulting aqueous raffinate solution contained an approximate TRU alpha activity of 0.02 nCi/g, which is well below the non-TRU waste limit of 10 nCi/g specified in 10 CFR 61.55. Favorable scrub and strip distribution coefficients were also observed for Am-241, Pu-238, and Pu-239, indicating the feasibility of recovering these isotopes from the TRUTEX solvent. A solution of 0.04 M 1-hydroxyethane-1,1-diphosphonic acid (HEDPA) in 0.04 M HNO3 was used to successfully strip the TRUs from the TRUEX solvent. The results of the test using actual ICPP dissolved zirconium calcine, and subsequent GTM evaluation, show the feasibility of removing TRUs from the dissolved zirconium calcine with the TRUEX solvent and the deleterious effects zirconium poses with the ICPP zirconium calcine waste. Test results using actual ICPP zirconium calcine reveal the necessity of preventing zirconium from following the TRUs

  15. Design and performance of atomizing nozzles for spray calcination of high-level wastes

    International Nuclear Information System (INIS)

    A key aspect of high-level liquid-waste spray calcination is waste-feed atomization by using air atomizing nozzles. Atomization substantially increases the heat transfer area of the waste solution, which enhances rapid drying. Experience from the spray-calciner operations has demonstrated that nozzle flow conditions that produce 70-μ median-volume-diameter or smaller spray droplets are required for small-scale spray calciners (drying capacity less than 80 L/h). For large-scale calciners (drying capacity greater than 300 L/h), nozzle flow conditions that produce 100-μ median-volume-diameter or smaller spray droplets are required. Mass flow ratios of 0.2 to 0.4, depending on nozzle size, are required for proper operation of internal-mix atomizing nozzles. Both internal-mix and external-mix nozzles have been tested at PNL. Due to the lower airflow requirements and fewer large droplets produced, the internal-mix nozzle has been chosen for primary development in the spray calciner program at PNL. Several nozzle air-cap materials for internal-mix nozzles have been tested for wear resistance. Results show that nozzle air caps of stainless steel and Cer-vit (a machineable glass ceramic) are suceptible to rapid wear by abrasive slurries, whereas air caps of alumina and reaction-bonded silicon nitride show only slow wear. Longer-term testing is necessary to determine more accurately the actual frequency of nozzle replacement. Atomizing nozzle air caps of alumina are subject to fracture from thermal shock, whereas air caps of silicon nitride and Cer-vit are not. Fractured nozzles are held in place by the air-cap retaining ring and continue to atomize satisfactorily. Therefore, fractures caused by thermal shocking do not necessarily result in nozzle failure

  16. Design and performance of atomizing nozzles for spray calcination of high-level wastes

    Energy Technology Data Exchange (ETDEWEB)

    Miller, F.A.; Stout, L.A.

    1981-05-01

    A key aspect of high-level liquid-waste spray calcination is waste-feed atomization by using air atomizing nozzles. Atomization substantially increases the heat transfer area of the waste solution, which enhances rapid drying. Experience from the spray-calciner operations has demonstrated that nozzle flow conditions that produce 70-..mu.. median-volume-diameter or smaller spray droplets are required for small-scale spray calciners (drying capacity less than 80 L/h). For large-scale calciners (drying capacity greater than 300 L/h), nozzle flow conditions that produce 100-..mu.. median-volume-diameter or smaller spray droplets are required. Mass flow ratios of 0.2 to 0.4, depending on nozzle size, are required for proper operation of internal-mix atomizing nozzles. Both internal-mix and external-mix nozzles have been tested at PNL. Due to the lower airflow requirements and fewer large droplets produced, the internal-mix nozzle has been chosen for primary development in the spray calciner program at PNL. Several nozzle air-cap materials for internal-mix nozzles have been tested for wear resistance. Results show that nozzle air caps of stainless steel and Cer-vit (a machineable glass ceramic) are suceptible to rapid wear by abrasive slurries, whereas air caps of alumina and reaction-bonded silicon nitride show only slow wear. Longer-term testing is necessary to determine more accurately the actual frequency of nozzle replacement. Atomizing nozzle air caps of alumina are subject to fracture from thermal shock, whereas air caps of silicon nitride and Cer-vit are not. Fractured nozzles are held in place by the air-cap retaining ring and continue to atomize satisfactorily. Therefore, fractures caused by thermal shocking do not necessarily result in nozzle failure.

  17. Extraction of potassium from K-feldspar via the CaCl2 calcination route☆

    Institute of Scientific and Technical Information of China (English)

    Bo Yuan; Chun Li; Bin Liang; Li Lü; Hairong Yue; Haoyi Sheng; Longpo Ye; Heping Xie

    2015-01-01

    The extraction of potassium from K-feldspar via a calcium chloride calcination route was studied with a focus on the effects of the calcination atmosphere, calcination temperature and time, mass ratio of CaCl2 to K-feldspar ore and particle size of the K-feldspar ore. The results demonstrated that a competing high-temperature hydrolysis reaction of calcium chloride with moisture in a damp atmosphere occurred concurrently with the conversion reaction of K-feldspar with CaCl2, thus reducing the amount of potassium extracted. The conversion reaction started at approximately 600 °C and accelerated with increasing temperature. When the temperature rose above 900 °C, the extraction of potassium gradually decreased due to the volatilization of the product, KCl. As much as approximately 41%of the potassium was volatilized in 40 min at 1100 °C. The mass ratio of CaCl2/K-feldspar ore significantly affected the extraction. At a mass ratio of 1.15 and 900 °C, the potassium extraction reached 91%in 40 min, while the extraction was reduced to only 22%at the theoretical mass ratio of 0.2. Optimal process conditions are as follows:ore particle size of 50–75μm, tablet forming pressure of 3 MPa, dry nitrogen atmosphere, mass ratio of CaCl2/ore 1.15:1, calcination temperature of 900 °C, and calcination time of 40 min. The XRD analysis revealed that a complex phase transition of the product SiO2 was also accompanied by the con-version reaction of K-feldspar/CaCl2. The SiO2 product formed at the initial stage was in the quartz phase at 900 °C and was gradually transformed into cristobalite after 30 min.

  18. Aggregating governance indicators

    OpenAIRE

    Kaufmann, Daniel; Kraay, Aart; Zoido-Lobaton, Pablo

    1999-01-01

    In recent years the growing interest of academics and policymakers in governance has been reflected in the proliferation of cross-country indices measuring various aspects of governance. The authors explain how a simple variant of an unobserved components model can be used to combine the information from these different sources into aggregate governance indicators. The main advantage of this method us that it allows quantification of the precision of both individual sources of governance data...

  19. Study of Recycled Concrete Aggregates

    OpenAIRE

    Jitender Sharma; Sandeep Singla

    2014-01-01

    This paper describes the introduction and production of recycled concrete aggregates and its various applications in the construction industry. In this paper, properties of recycled aggregates and its comparison with the natural aggregates are also mentioned. Future recommendations about RCA are also included.

  20. Proteins aggregation and human diseases

    Science.gov (United States)

    Hu, Chin-Kun

    2015-04-01

    Many human diseases and the death of most supercentenarians are related to protein aggregation. Neurodegenerative diseases include Alzheimer's disease (AD), Huntington's disease (HD), Parkinson's disease (PD), frontotemporallobar degeneration, etc. Such diseases are due to progressive loss of structure or function of neurons caused by protein aggregation. For example, AD is considered to be related to aggregation of Aβ40 (peptide with 40 amino acids) and Aβ42 (peptide with 42 amino acids) and HD is considered to be related to aggregation of polyQ (polyglutamine) peptides. In this paper, we briefly review our recent discovery of key factors for protein aggregation. We used a lattice model to study the aggregation rates of proteins and found that the probability for a protein sequence to appear in the conformation of the aggregated state can be used to determine the temperature at which proteins can aggregate most quickly. We used molecular dynamics and simple models of polymer chains to study relaxation and aggregation of proteins under various conditions and found that when the bending-angle dependent and torsion-angle dependent interactions are zero or very small, then protein chains tend to aggregate at lower temperatures. All atom models were used to identify a key peptide chain for the aggregation of insulin chains and to find that two polyQ chains prefer anti-parallel conformation. It is pointed out that in many cases, protein aggregation does not result from protein mis-folding. A potential drug from Chinese medicine was found for Alzheimer's disease.

  1. Influence of calcination temperature on structural and magnetic properties of nanocomposites formed by Co-ferrite dispersed in sol-gel silica matrix using tetrakis(2-hydroxyethyl orthosilicate as precursor

    Directory of Open Access Journals (Sweden)

    Gharagozlou Mehrnaz

    2011-04-01

    Full Text Available Abstract Effects of calcination temperatures varying from 400 to 1000°C on structural and magnetic properties of nanocomposites formed by Co-ferrite dispersed in the sol-gel silica matrix using tetrakis(2-hydroxyethyl orthosilicate (THEOS as water-soluble silica precursor have been investigated. Studies carried out using XRD, FT-IR, TEM, STA (TG-DTG-DTA and VSM techniques. Results indicated that magnetic properties of samples such as superparamagnetism and ferromagnetism showed great dependence on the variation of the crystallinity and particle size caused by the calcination temperature. The crystallization, saturation magnetization Ms and remenant magnetization Mr increased as the calcination temperature increased. But the variation of coercivity Hc was not in accordance with that of Ms and Mr, indicating that Hc is not determined only by the crystallinity and size of CoFe2O4 nanoparticles. TEM images showed spherical nanoparticles dispersed in the silica network with sizes of 10-30 nm. Results showed that the well-established silica network provided nucleation locations for CoFe2O4 nanoparticles to confinement the coarsening and aggregation of nanoparticles. THEOS as silica matrix network provides an ideal nucleation environment to disperse CoFe2O4 nanoparticles and thus to confine them to aggregate and coarsen. By using THEOS as water-soluble silica precursor over the currently used TEOS and TMOS, the organic solvents are not needed owing to the complete solubility of THEOS in water. Synthesized nanocomposites with adjustable particle sizes and controllable magnetic properties make the applicability of Co-ferrite even more versatile.

  2. Alliance between chemical industry Astral Calcining, India, and energy company E.On Benelux; Verbond chemie en energie [tussen Astral Calcining, India en E.On Benelux

    Energy Technology Data Exchange (ETDEWEB)

    Roggen, M. (ed.)

    2003-03-01

    The Indian chemical concern Astral Calcining (produces carbon for the aluminium industry) will supply high-pressure steam to the energy company E.ON Benelux, to be used by Lyondell Bayer (producer of propylene oxide). In exchange, Astral will receive electricity from E.On Benelux. This is a unique co-operation between companies with different production processes and cultures. [Dutch] Het Indiase chemieconcern Astral gaat aan E.ON Benelux hogedruk stoom leveren die bestemd is voor Lyondell Bayer. In ruil daarvoor ontvangt Astral elektriciteit. Een unieke samenwerking tussen concerns met totaal andere productieprocessen en uiteenlopende culturen.

  3. Absorption Spectra of Astaxanthin Aggregates

    CERN Document Server

    Olsina, Jan; Minofar, Babak; Polivka, Tomas; Mancal, Tomas

    2012-01-01

    Carotenoids in hydrated polar solvents form aggregates characterized by dramatic changes in their absorption spectra with respect to monomers. Here we analyze absorption spectra of aggregates of the carotenoid astaxanthin in hydrated dimethylsulfoxide. Depending on water content, two types of aggregates were produced: H-aggregates with absorption maximum around 390 nm, and J-aggregates with red-shifted absorption band peaking at wavelengths >550 nm. The large shifts with respect to absorption maximum of monomeric astaxanthin (470-495 nm depending on solvent) are caused by excitonic interaction between aggregated molecules. We applied molecular dynamics simulations to elucidate structure of astaxanthin dimer in water, and the resulting structure was used as a basis for calculations of absorption spectra. Absorption spectra of astaxanthin aggregates in hydrated dimethylsulfoxide were calculated using molecular exciton model with the resonance interaction energy between astaxanthin monomers constrained by semi-e...

  4. Influence of the Calcination Temperature on the Combustion Synthesized Perovskite LaMnO3 Compound

    Directory of Open Access Journals (Sweden)

    A.R. Shelke

    2015-10-01

    Full Text Available A simple combustion method based on principles of propellent chemistry in which Polyvinyl alcohol (PVA as fuel and nitrates as oxidizer were used for synthesizing the perovskite like LaMnO3 powders. The oxidizer to fuel ratio was maintained at 5 : 1. The darkish black powder obtained was calcined at 800 °C and 1000 °C for 5 hour. The combustion and thermal decomposition of the precursor were investigated using the TG-DTA and Fourier Transform Infra-Red (FT-IR techniques. The X-ray diffraction (XRD pattern of all three samples i.e., un-heated LaMnO3 powder (LMO-UH, calcined at 800 °C (LMO-800 and at 1000 °C (LMO-1000 were carried out. The single phase orthorhombic crystal structure was revealed to crystallize at LMO-800 and LMO-1000 with elevation in the crystalline size. A small impurity peak at 28.7° was seen of Mn3O4 for LMO-UH, which vanished after calcining it. The strong absorption in FT-IR spectra found at around 615 cm – 1 was due to the formation of metal-oxygen (M-O bond. Moreover a small shift in this M-O bond with increase in calcination temperature suggested the strained LaMnO3 compound. Elemental analysis using the energy dispersive X-ray fluorescence spectrometer (EDXRF indicated the presence of La and Mn with increase in the Mn contents after calcinations. The oxygen, nitrogen and hydrogen content in the sample were determined from the ONH analysis indicating a decrease in the oxygen content for LMO-800. Well defined porous-foam like morphology of the sample was achieved from scanning electron microscopic (SEM study, which become compact with calcination process. Magnetic properties were found to transform from the ferromagnetic-to-paramagnetic phase for LMO-UH sample, while reduction in magnetization values and coercivity at low temperatures was obtained for LMO-800 and LMO-1000 samples.

  5. Influence of calcination on the adsorptive removal of phosphate by Zn-Al layered double hydroxides from excess sludge liquor

    International Nuclear Information System (INIS)

    The influence of calcination of Zn-Al layered double hydroxides (LDHs) on their phosphate adsorption capacity was studied in order to improve phosphorus removal from an excess sludge liquor. Powder X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), thermogravimetry-differential scanning calorimetry (TG-DSC) and nitrogen adsorption-desorption were employed to characterize the raw Zn-Al and the calcined products. The results reveal that the Zn-Al LDHs evolved to a phase of mixed metal oxides with the calcination temperature increasing to 300 deg. C and finally to spinel ZnAl2O4 at 600 deg. C. When the Zn-Al was calcined at 300 deg. C, the interlayer carbonate ions were removed and the greatest BET surface area of 81.20 m2/g was achieved. The tested phosphate adsorption capacities of the raw and calcined Zn-Al were closely related to the evolution of physicochemical properties of the LDHs during the calcination. The Zn-Al-300 (Zn-Al LDHs calcined at 300 deg. C) exhibited the highest P uptake of 41.26 mg P/g in 24 h. The phosphate adsorption by the raw Zn-Al and the Zn-Al-300 both follows a pseudo-second-order kinetic model; the adsorption isotherms show a good fit with a Langmuir-type equation.

  6. Stepwise charging and calcination atmosphere effects for iron and nickel substituted lithium manganese oxide positive electrode material

    Science.gov (United States)

    Tabuchi, Mitsuharu; Kageyama, Hiroyuki; Shibuya, Hideka; Doumae, Kyosuke; Yuge, Ryota; Tamura, Noriyuki

    2016-05-01

    Fe- and Ni-substituted Li2MnO3 (Li1+x(FeyNiyMn1-2y)1-xO2, 0 < x < 1/3, y = 0.1, 0.15, 0.2) was prepared using coprecipitation-calcination. Its electrochemical properties were sensitive to the calcining atmosphere or the charging mode. Calcination in N2 atmosphere or selecting stepwise charging mode respectively engender better electrochemical performance than calcination in an air atmosphere or selecting galvanostatic charging mode. In fact, the sample for which y = 0.15 calcined in N2 atmosphere exhibited higher discharge capacity than that for the sample calcined in air atmosphere when stepwise charging mode was selected. By selecting stepwise charging mode instead of galvanostatic charging mode, the initial discharge capacity was increased and cyclability was improved. Among the samples calcined in N2 atmosphere, samples for which y = 0.1 and 0.15 were found to have attractive composition as positive electrode materials by selecting stepwise charging mode.

  7. Influence of calcination on the adsorptive removal of phosphate by Zn-Al layered double hydroxides from excess sludge liquor.

    Science.gov (United States)

    Cheng, Xiang; Huang, Xinrui; Wang, Xingzu; Sun, Dezhi

    2010-05-15

    The influence of calcination of Zn-Al layered double hydroxides (LDHs) on their phosphate adsorption capacity was studied in order to improve phosphorus removal from an excess sludge liquor. Powder X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), thermogravimetry-differential scanning calorimetry (TG-DSC) and nitrogen adsorption-desorption were employed to characterize the raw Zn-Al and the calcined products. The results reveal that the Zn-Al LDHs evolved to a phase of mixed metal oxides with the calcination temperature increasing to 300 degrees C and finally to spinel ZnAl(2)O(4) at 600 degrees C. When the Zn-Al was calcined at 300 degrees C, the interlayer carbonate ions were removed and the greatest BET surface area of 81.20 m(2)/g was achieved. The tested phosphate adsorption capacities of the raw and calcined Zn-Al were closely related to the evolution of physicochemical properties of the LDHs during the calcination. The Zn-Al-300 (Zn-Al LDHs calcined at 300 degrees C) exhibited the highest P uptake of 41.26 mg P/g in 24h. The phosphate adsorption by the raw Zn-Al and the Zn-Al-300 both follows a pseudo-second-order kinetic model; the adsorption isotherms show a good fit with a Langmuir-type equation. PMID:20060217

  8. Influence of calcination on the adsorptive removal of phosphate by Zn-Al layered double hydroxides from excess sludge liquor

    Energy Technology Data Exchange (ETDEWEB)

    Cheng Xiang, E-mail: sean.d.cheng@gmail.com [School of Municipal and Environmental Engineering, Harbin Institute of Technology, 202 Haihe Road, 150090 Harbin (China); Huang Xinrui [School of Municipal and Environmental Engineering, Harbin Institute of Technology, 202 Haihe Road, 150090 Harbin (China); Wang Xingzu; Sun Dezhi [College of Environmental Science and Engineering, Beijing Forestry University, 35 Tsinghua East Road, 100083 Beijing (China)

    2010-05-15

    The influence of calcination of Zn-Al layered double hydroxides (LDHs) on their phosphate adsorption capacity was studied in order to improve phosphorus removal from an excess sludge liquor. Powder X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), thermogravimetry-differential scanning calorimetry (TG-DSC) and nitrogen adsorption-desorption were employed to characterize the raw Zn-Al and the calcined products. The results reveal that the Zn-Al LDHs evolved to a phase of mixed metal oxides with the calcination temperature increasing to 300 deg. C and finally to spinel ZnAl{sub 2}O{sub 4} at 600 deg. C. When the Zn-Al was calcined at 300 deg. C, the interlayer carbonate ions were removed and the greatest BET surface area of 81.20 m{sup 2}/g was achieved. The tested phosphate adsorption capacities of the raw and calcined Zn-Al were closely related to the evolution of physicochemical properties of the LDHs during the calcination. The Zn-Al-300 (Zn-Al LDHs calcined at 300 deg. C) exhibited the highest P uptake of 41.26 mg P/g in 24 h. The phosphate adsorption by the raw Zn-Al and the Zn-Al-300 both follows a pseudo-second-order kinetic model; the adsorption isotherms show a good fit with a Langmuir-type equation.

  9. Aggregate Demand and Supply

    OpenAIRE

    Farmer, Roger E.A.

    2007-01-01

    This paper is part of a broader project that provides a microfoundation to the General Theory of J.M. Keynes. I call this project 'old Keynesian economics' to distinguish it from new-Keynesian economics, a theory that is based on the idea that to make sense of Keynes we must assume that prices are sticky. I describe a multi-good model in which I interpret the definitions of aggregate demand and supply found in the General Theory through the lens of a search theory of the labor market. I argue...

  10. Aggregation of smooth preferences

    OpenAIRE

    Norman Schofield

    1998-01-01

    Suppose p is a smooth preference profile (for a society, N) belonging to a domain PN. Let be a voting rule, and (p)(x) be the set of alternatives in the space, W, which is preferred to x. The equilibrium E((p)) is the set {x∈W:(p)(x) is empty}. A sufficient condition for existence of E((p)) when p is convex is that a "dual", or generalized gradient, d(p)(x), is non-empty at all x. Under certain conditions the dual "field", d(p), admits a "social gradient field" (p). is called an "aggregator" ...

  11. Concrete = aggregate, cement, water?

    International Nuclear Information System (INIS)

    Concrete for the Temelin nuclear power plant is produced to about 70 different formulae. For quality production, homogeneous properties of aggregates, accurate proportioning devices, technological discipline and systematic inspections and tests should be assured. The results are reported of measuring compression strength after 28 days for different concrete samples. The results of such tests allow reducing the proportion of cement, which brings about considerable savings. Reduction in cement quantities can also be achieved by adding ash to the concrete mixes. Ligoplast, a plasticizer addition is used for improving workability. (M.D). 8 figs

  12. JC properties and microstructures of YBCO films fabricated by low temperature calcination in TFA-MOD method

    International Nuclear Information System (INIS)

    YBa2Cu3O7-δ (YBCO) films were grown on LaAlO3 substrates by a metal organic deposition using trifluoroacetates (TFA-MOD). In this study, effects of calcination condition such as temperature on microstructures and Jc properties for the YBCO films were studied. The TFA starting solution was coated on a substrate by a spin-coating method. Then, a two-step heat treatment was applied to the coated films. In the calcination step, the coated film was calcined to form a homogeneous amorphous precursor by increasing the temperature which was varied from 300 deg. C to 500 deg. C at a constant heating rate of 2 deg. C/min. The prepared precursor films were crystallized at a constant condition. As a result, Jc value depended on the calcination temperature, YBCO film calcined at 400 deg. C showed the highest Jc of 2.5 MA/cm2. Jc's for the YBCO films calcined at 300 deg. C and 350 deg. C were 1.9 MA/cm2 and 2.0 MA/cm2, respectively. On the other hand, YBCO film calcined at 500 deg. C showed the lowest Jc of 1.4 MA/cm2. Cross-sectional TEM images showed that the YBCO film calcined at 400 deg. C had less pores and small size of pores in the crystallized film randomly throughout the film. Large pores were observed in the YBCO film calcined at 500 deg. C. Also, these large pores were existed near substrate in the YBCO film. It is considered that the differences of these pore formation mechanisms are the main cause of the difference of Jc characteristic.

  13. Taurine and platelet aggregation

    International Nuclear Information System (INIS)

    Taurine is a putative neurotransmitter or neuromodulator. The endogenous taurine concentration in human platelets, determined by amino acid analysis, is 15 μM/g. In spite of this high level, taurine is actively accumulated. Uptake is saturable, Na+ and temperature dependent, and suppressed by metabolic inhibitors, structural analogues, and several classes of centrally active substances. High, medium and low affinity transport processes have been characterized, and the platelet may represent a model system for taurine transport in the CNS. When platelets were incubated with 14C-taurine for 30 minutes, then resuspended in fresh medium and reincubated for one hour, essentially all of the taurine was retained within the cells. Taurine, at concentrations ranging from 10-1000 μM, had no effect on platelet aggregation induced by ADP or epinephrine. However, taurine may have a role in platelet aggregation since 35-39% of the taurine taken up by human platelets appears to be secreted during the release reaction induced by low concentrations of either epinephrine or ADP, respectively. This release phenomenon would imply that part of the taurine taken up is stored directly in the dense bodies of the platelet

  14. A parametric study of a solar calcinator using computational fluid dynamics

    International Nuclear Information System (INIS)

    In this work a horizontal rotating solar calcinator is studied numerically using computational fluid dynamics. The specific solar reactor is a 10 kW model designed and used for efficiency studies. The numerical model is based on the solution of the Navier-Stokes equations for the gas flow, and on Lagrangean dynamics for the discrete particles. All necessary mathematical models were developed and incorporated into a computational fluid dynamics model with the influence of turbulence simulated by a two-equation (RNG k-ε) model. The efficiency of the reactor was calculated for different thermal inputs, feed rates, rotational speeds and particle diameters. The numerically computed degrees of calcination compared well with equivalent experimental results

  15. Mg Al2 O4-Si C composites. Influence of the calcination atmosphere

    International Nuclear Information System (INIS)

    Alumina-magnesia spinel is a ceramic material with excellent physicochemical properties. The addition of a second phase like silicon carbide is with the objective of enhance its thermochemical properties. The preparation and sintering of spinel with Si C is studied. The samples were isostatically pressed at 200 Mpa. Calcination were performed under different atmospheres: air, Ar, CO and N2. Compacts after calcination were studied using XRD and Hg-density. Chemical interactions between Si C and spinel were observed depending on the atmosphere employed. Under Ar, spinel is partially reduced by the Si C producing the weight loss of the samples. Under N2 nitrogenous phases of the system Si-Al-O-N are formed and densities are near 90%. The reactions that takes place are explained taking into to account the atmosphere use. (author)

  16. Separation of Zinc from High Iron-Bearing Zinc Calcines by Reductive Roasting and Leaching

    Science.gov (United States)

    Peng, Bing; Peng, Ning; Min, Xiao-Bo; Liu, Hui; Li, Yanchun; Chen, Dong; Xue, Ke

    2015-09-01

    This paper focuses on the selective leaching of zinc from high iron-bearing zinc calcines. The FactSage 6.2 program was used for the thermodynamic analysis of the selective reduction and leaching, and the samples reduced by carbon and carbon monoxide were subjected to acid leaching for the separation of zinc from iron. It is shown that the generation of ferrous oxide should be avoided by modifying V CO ( P CO/( P CO + )) in the roasting process prior to the selective leaching of zinc. Gaseous roasting-leaching has a higher efficiency in the separation of zinc from iron than carbothermic reduction-leaching. The conversion of the zinc ferrite in high iron-bearing zinc calcines to zinc oxide and magnetite has been demonstrated by x-ray diffraction (XRD) and magnetic hysteresis loop characterization. This gaseous roast-leach process is technically feasible to separate zinc from iron without an iron precipitation process.

  17. Evaluation and selection of aqueous-based technology for partitioning radionuclides from ICPP calcine

    International Nuclear Information System (INIS)

    Early in 1993 Westinghouse Idaho Nuclear Company (WINCO) chartered a Panel of Nuclear Separations Experts. The purpose of this Panel was to assist WINCO scientists and engineers in selecting, evaluating, and ranking candidate aqueous-based processes and technologies for potential use in partitioning selected radionuclides from nitric acid solutions of retrieved Idaho Chemical Processing Plant (ICPP) calcine. Radionuclides of interest are all transuranium elements, 90Sr, 99Tc, 129I, and 137Cs. The six man Panel met for 4 days (February 16--19, 1993) on the campus of the Idaho State University in Pocatello, Idaho. Principal topics addressed included: Available radionuclide removal technology; applicability of separations technology and processes to ICPP calcine; and potential integrated radionuclide partitioning schemes. This report, prepared from contributions from all Panel members, presents a comprehensive account of the proceedings and significant findings of the February, 1993 meeting in Pocatello

  18. Ethanol Total Oxidation Over Calcined Layered Double Hydroxides Modified with Organic Components

    Directory of Open Access Journals (Sweden)

    Kovanda, F.

    2013-05-01

    Full Text Available Coprecipitation of Co, Mn, and Al nitrates by a solution of Na2CO3 and NaOH in the presence of Pluronic ® P123 has led to layered double hydroxide (LDH precursors with hydrotalcite-like structure. Their calcination gave spinel-type mixed oxides; the presence of organic template increased both BET and mesopore surface areas of the calcined products. TPR profiles of the samples modified with Pluronic ® P123 exhibited a shift of reduction maxima to lower temperatures, similarly as increasing sodium content in the catalysts. However, though the physical-chemical properties of Co-Mn-Al mixed oxides and their catalytic activity in ethanol oxidation were slightly improved, the changes evolved by the presence of Pluronic ® P123 during precipitation of LDH precursors were rather small.

  19. Conceptual design for remote handling methods using the HIP process in the Calcine Immobilization Program

    International Nuclear Information System (INIS)

    This report recommends the remote conceptual design philosophy for calcine immobilization using the hot isostatic press (HIP) process. Areas of remote handling operations discussed in this report include: (1) introducing the process can into the front end of the HIP process, (2) filling and compacting the calcine/frit mixture into the process can, (3) evacuating and sealing the process can, (4) non-destructive testing of the seal on the process can, (5) decontamination of the process can, (6) HIP furnace loading and unloading the process can for the HIPing operation, (7) loading an overpack canister with processed HIP cans, (8) sealing the canister, with associated non-destructive examination (NDE) and decontamination, and (9) handling canisters for interim storage at the Idaho Chemical Processing Plant (ICPP) located on the Idaho National Engineering Laboratory (INEL) site

  20. Influence of Calcination on the Physical Characteristics and Nitrogen Removal Performance of Clinoptilolites

    Institute of Scientific and Technical Information of China (English)

    LIN Hai; JIN Xin; DONG Yingbo; HUO Hanxin; LIU Quanli

    2014-01-01

    The influences of roasting activation on the particle morphology, microscopic structure, and adsorption properties of natural clinoptilolites were investigated. The experimental results show that the optimal modified conditions include a calcination temperature at 400℃, a roasting time of 0.5 h, and furnace cooling. The ammonia nitrogen removal rate from analog renewable water of the modified clinoptilolites reached 72%in the optimized conditions, which is 12%higher than that of natural ones. Scanning electron microscopy analysis showed that the surface morphology changed, the micro-hole size increased, and the surface became smoother and more uniform after calcination. The single-point total adsorption average pore width increased from 7.74 nm to 10.64 nm.

  1. Effect of Reaction Rate and Calcination Time on CaNb2O6 Nanoparticles

    International Nuclear Information System (INIS)

    The properties of CaNb2O6 nanoparticles synthesized by coprecipitation method under controlled reaction rate and extended calcination time were studied. Analysis of the X-ray diffraction pattern shows single orthorhombic phase of the material with lattice parameters: a=15.0147Å, b =5.74148 Å, and c=5.30296 Å. The morphology and size of particles was found to be improved due to the controlled reaction rate and extended calcination time. The average sizes of the particles were estimated as 40 nm and 90 nm for sintering temperatures 650°C and 800°C, respectively. The material was found to possess dielectric constant which is inversely proportional to the frequency. Surprisingly, the material shows ferroelectric behavior, the possible origin of which is discussed here.

  2. Early and Late Strength Characterization of Portland Cement Containing Calcined Low-Grade Kaolin Clay

    OpenAIRE

    Mark Bediako; Gawu, S. K. Y.; A. A. Adjaottor; John Solomon Ankrah

    2016-01-01

    Heat treated low-grade kaolin clays are now considered as a suitable pozzolanic material to metakaolins. However their suitability as a good pozzolanic material depends on the geochemistry and structure of the clay which is usually influenced by the geographical environment. This study investigated a low-grade kaolin clay from Nyamebekyere in the Ashanti Region of Ghana. The influence of the calcined material on the early and late strength development of Portland cement was analyzed. The earl...

  3. 3.6. The kinetics of sulfuric acid decomposition of calcined concentrate of borosilicate ore

    International Nuclear Information System (INIS)

    Present article is devoted to kinetics of sulfuric acid decomposition of calcined concentrate of borosilicate ore. The experimental data of kinetics of extraction of boron oxide from danburite at sulfuric acid decomposition were obtained at 20-90 deg C temperature range and process duration 15-90 minutes. The flowsheet of obtaining of boric acid from borosilicate ores of Ak-Arkhar Deposit by sulfuric acid method was proposed.

  4. In-situ investigation of the calcination process of mixed oxide xerogels with Raman spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Panitz, J.C. [Paul Scherrer Inst. (PSI), Villigen (Switzerland)

    1997-06-01

    The controlled calcination of materials derived by sol-gel reactions is important for the evolution of the final structure. Raman spectroscopy is an ideal tool for the identification of surface species under in-situ conditions, as demonstrated in the following for the example of a molybdenum oxide-silica xerogel. Raman spectra of this particular sample were recorded at temperatures as high as 1173 K, and compared with those of a reference material.(author) 3 figs., 4 refs.

  5. Various durability aspects of calcined Kaolin-blended Portland cement pastes and concretes

    OpenAIRE

    SAILLIO, Mickael; BAROGHEL BOUNY, Véronique; PRADELLE, Sylvain

    2015-01-01

    The use of calcined clay, in the form of metakaolin (MK), as a pozzolanic constituent for concrete has received considerable attention in recent years, due to the lower CO2 emission of this supplementary cementitious material compared to the production of a classic portland cement. Furthermore, concretes incorporating MK show some improve durability properties. In this paper, the durability of concretes and cement pastes with MK as partial replacement of cement (10 and 25%) has been investiga...

  6. Rotary Calciner - Metallic Melter and Slurry - Fed Ceramic Melter for Treatment of High Level Liquid Waste

    International Nuclear Information System (INIS)

    Rotary calciner-metallic melter and slurry-fed ceramic melter are used for treatment of high level liquid waste in the industrial scale. Rotary calciner-metallic melter is operated by induction heating and slurry-fed ceramic melter by Joule heating. Both of melter are compared it’s characteristics of waste-glass composition for process and melter operation, melter materials, life time of melter, treatment of off gas, and power consumption. For melter with Joule heating, electric resistance of waste-glass is 4.8 ohm.cm at temperature 1150 °C. The metal of platinum group is not soluble in the molten waste-glass, so that influence the electric current pass by the molten waste-glass. For melter with induction heating there is not influence of platinum metal group. For melter with Joule heating, the material which contact with waste-glass is monofrax K-3. The outer materials layer i.e MRT-70K, LN-135, AZ-GS, fiber board, and stainless steel 304. The material of melter with induction heating is Inconel-690. The life time of melter with Joule heating is longer than melter with induction heating. From the safety aspect, operation of the both of melter have already successful. Operation cost of slurry-fed ceramic melter is cheaper, but construction and decommissioning cost more expensive than rotary calciner-metallic melter. Based on Indonesia condition, the slurry-fed ceramic melter is more reasonable to be utilized. (author)

  7. Connecting section and associated systems concept for the spray calciner/in-can melter process

    International Nuclear Information System (INIS)

    For a number of years, researchers at the Pacific Northwest Laboratory have been developing processes and equipment for converting high-level liquid wastes to solid forms. One of these processes is the Spray Calciner/In-Can Melter system. To immobilize high-level liquid wastes, this system must be operated remotely, and the calcine must be reliably conveyed from the calciner to the melting furnace. A concept for such a remote conveyance system was developed at the Pacific Northwest Laboratory, and equipment was tested under full-scale, nonradioactive conditions. This concept and the design of demonstration equipment are described, and the results of equipment operation during experimental runs of 7 d are presented. The design includes a connecting section and its associated systems - a canister sypport and alignment concept and a weight-monitoring system for the melting furnace. Overall, the runs demonstrated that the concept design is an acceptable method of connecting the two pieces of process equipment together. Although the connecting section has not been optimized in all areas of concern, it provides a first-generation design of a production-oriented system

  8. Synthesis and luminescence of Eu3+ doped hydroxyapatite nanocrystallines: Effects of calcinations and Eu3+ content

    International Nuclear Information System (INIS)

    Eu3+ doped hydroxyapatite (Eu-HAP) luminescent nanocrystallines were prepared by ultrasound assisted precipitation method. Aiming to seek a compromise proposal for achieving high luminescence and nanocrystallines, the effects of calcinations temperature and Eu3+ doping content on luminescence property as well as phase composition, crystal size and crystallinity of Eu-HAP crystals were investigated. The results showed that the luminescence of Eu-HAP was enhanced by the thermal treatment and the increasing Eu doping content. However, the higher temperature and the excess Eu resulted in the size increase and phase composition change of HAP respectively. The 2% Eu doping content and calcinations temperature of 600 °C were preferred for preparing Eu-HAP nanocrystallines with strong luminescence. The Eu-HAP nanocrystallines were about 20–40 nm in diameter (TEM) and could be well dispersed in water to form aqueous suspension of about 140 nm (DLS intensity-averaged diameter). Eu-HAP nanocrystalline could be used as a fluorescent probe for cell labeling. - Highlights: ► 20–40 nm Eu-HAP luminescent nanocrystallines were prepared by the precipitation method. ► 2% Eu doping content and calcinations at 600 °C were preferred to prepare Eu-HAP. ► Eu-HAP nanocrystallines could be well dispersed to form aqueous suspension. ► Eu-HAP nanocrystallines could be used as cell labels.

  9. Mobile calcination and cementation unit for solidification of concentrated radioactive wastes

    International Nuclear Information System (INIS)

    Mobile experimental unit MESA-1 was developed and manufactured for processing radioactive concentrates by direct cementation. The unit is mainly designed for processing low-level liquid wastes from nuclear power plants and other nuclear installations, in which the level of radioactivity does not exceed 1010 Bq/m3, the salt content of liquid solutions does not exceed 500 kg/m3 and the maximum amount of boric acid is 130 kg/m3. The equipment is built into three modules which may be assembled and dismantled in a short time and transported separately. The unit without the calciner module was tested in non-radioactive mode and in operation with actual radioactive wastes from the V-1 nuclear power plant. The course and results of the tests are described in detail. All project design values were achieved, a total of 18 dm3 model solutions were processed and 1 m3 of actual wastes with a salt content of 450 kg/m3. The test showed that with regard to the radiation level reached it will be necessary in the process of calcination to increase the shielding of certain exposed points. The calciner module is being assembled for completion. (Z.M.)

  10. Processing of concentrated radioactive wastes into cement and bitumens following calcination

    International Nuclear Information System (INIS)

    A brief characteristic is presented of the most frequently used processes of solidification of liquid radioactive wastes, viz., bituminization, cementation and their combination with calcination. The effect of individual parameters is assessed on the choice of the type of solidification process as is their importance in the actual process, in temporary storage, during transportation and under conditions of long-term storage. It has been found that a combination of the procedures could lead to a modular system of methods and equipment. This would allow to approach optimal solidification of wastes in the present period and to establish a research reserve for the development of more modern, economically advantageous and safer procedures. A rough estimate is made of the costs of the solidification of 1 m3 of radioactive concentrate from the V-1 power plant at a production of 380 m3/year, this for the cementation-calcination and bituminization-calcination procedures. The said rough economic analysis only serves to identify the major operating components which have the greatest effect on the economic evaluation of the solidification procedures. (Z.M.)

  11. Numerical study of co-firing pulverized coal and biomass inside a cement calciner.

    Science.gov (United States)

    Mikulčić, Hrvoje; von Berg, Eberhard; Vujanović, Milan; Duić, Neven

    2014-06-24

    The use of waste wood biomass as fuel is increasingly gaining significance in the cement industry. The combustion of biomass and particularly co-firing of biomass and coal in existing pulverized-fuel burners still faces significant challenges. One possibility for the ex ante control and investigation of the co-firing process are computational fluid dynamics (CFD) simulations. The purpose of this paper is to present a numerical analysis of co-firing pulverized coal and biomass in a cement calciner. Numerical models of pulverized coal and biomass combustion were developed and implemented into a commercial CFD code FIRE, which was then used for the analysis. Three-dimensional geometry of a real industrial cement calciner was used for the analysis. Three different co-firing cases were analysed. The results obtained from this study can be used for assessing different co-firing cases, and for improving the understanding of the co-firing process inside the calculated calciner. PMID:24963094

  12. High-level waste vitrification by spray calcination/in-can melting

    Energy Technology Data Exchange (ETDEWEB)

    Larson, D.E.; Bonner, W.F. (comp.)

    1976-11-01

    Federal regulations require that high-level liquid waste (HLLW) be converted to a solid for custody in a Federal repository. The Spray Solidification/In-Can Melting process has been developed and is being demonstrated for commercial application. The bases used are similar to those of the NFS plant and to anticipated regulations for waste canister receipt at a Federal repository. The reference NFS flowsheet combines plant HA Column Wastes, Low-Level Wastes, and various HLLW process recycle streams to produce a borosilicate glass. After the canister is filled and sealed, the lid weld will be inspected and decontaminated. Equipment and instrumentation for feed supply to the calciner, calcination, melting, welding, weld inspection, canister decontamination, and in-cell canister storage are being designed and demonstrated. Preliminary facility layouts, equipment design data, and instrumentation needs are provided for major process equipment systems. Additional demonstration work is being performed to verify and complete the plant scale equipment design, including full-scale nonradioactive equipment testing, nonradioactive facility mockup for equipment remote operation and maintenance demonstration, and pilot plant production of waste glass from commercial fuel HLLW. The technology for spray calcination and in-can melting is ready for commercial application. Required additional work is described. A preliminary evaluation is made of materials that may be released from the process from normal and abnormal operations in the facility. 34 figures, 20 tables. (DLC)

  13. Removal of nickel on Bofe bentonite calcined clay in porous bed

    Energy Technology Data Exchange (ETDEWEB)

    Vieira, M.G.A.; Neto, A.F. Almeida [UNICAMP/FEQ/DTF, Campinas, SP (Brazil); Gimenes, M.L. [UEM/CTC/DEQ, Campinas, SP (Brazil); Silva, M.G.C. da, E-mail: meuris@feq.unicamp.br [UNICAMP/FEQ/DTF, Campinas, SP (Brazil)

    2010-04-15

    Bentonite clays have been showing good adsorbing characteristics and are used as an alternative material in the removal of heavy metals. The purpose of this study is to evaluate the removal of nickel on Bofe bentonite calcined clay in porous bed. Firstly, a study was conducted to define the operation outflow, based on the minimum mass transfer zone (MTZ) obtained, useful (q{sub U}) and total adsorbed (q{sub T}) removal amounts and total nickel removal percentage (Rem (%)). Assays of nickel adsorption on clay were conducted according to a 2{sup 2} factorial design with three central points to evaluate the effect of the particle diameter and initial adsorbate concentration on variables q{sub U}, q{sub T} and Rem (%). Tests to obtain the adsorbent physical and chemical characteristics were performed on samples of Bofe clay in natura, calcined, and calcined submitted to nickel adsorption. This clay was characterized according to the following techniques: Energy Dispersive Spectroscopy (EDS), Thermogravimetry (TG), Differential Scanning Calorimetry (DSC), X-ray Diffraction (XRD), Fourier Transformed Infrared Spectroscopy (FTIR), Physisorption of N{sub 2} (BET), Helium Picnometry and Scanning Electron Microscope (SEM) with metal mapping.

  14. Oxyfuel carbonation/calcination cycle for low cost CO2 capture in existing power plants

    International Nuclear Information System (INIS)

    Postcombustion CO2 capture is the best suitable capture technology for existing coal power plants. This paper focuses on an emerging technology that involves the separation of CO2 using the reversible carbonation reaction of CaO to capture CO2 from the flue gas, and the calcination of CaCO3 to regenerate the sorbent and produce concentrated CO2 for storage. We describe the application to this concept to an existing (with today's technology) power plant. The added capture system incorporates a new supercritical steam cycle to take advantage of the large amount of heat coming out from the high temperature capture process (oxyfired combustion of coal is needed in the CaCO3 calciner). In these conditions, the capture system is able to generate additional power (26.7% efficiency respect to LHV coal input to the calciner after accounting for all the penalties in the overall system), without disturbing the steam cycle of the reference plant (that retains its 44.9 efficiency). A preliminary cost study of the overall system, using well established analogues in the open literature for the main components, yields capture cost around 16 Euro /ton CO2 avoided and incremental cost of electricity of just over 1 Euro /MW h e

  15. DECONTAMINATION OF PLUTONIUM FOR FLUORIDE AND CHLORIDE DURING OXALATE PRECIPITATION, FILTRATION AND CALCINATION PROCESSES

    Energy Technology Data Exchange (ETDEWEB)

    Kyser, E.

    2012-07-25

    Due to analytical limitations for the determination of fluoride (F) and chloride (Cl) in a previous anion exchange study, an additional study of the decontamination of Pu from F and Cl by oxalate precipitation, filtration and calcination was performed. Anion product solution from the previous impurity study was precipitated as an oxalate, filtered, and calcined to produce an oxide for analysis by pyrohydrolysis for total Cl and F. Analysis of samples from this experiment achieved the purity specification for Cl and F for the proposed AFS-2 process. Decontamination factors (DF's) for the overall process (including anion exchange) achieved a DF of {approx}5000 for F and a DF of {approx}100 for Cl. Similar experiments where both HF and HCl were spiked into the anion product solution to a {approx}5000 {micro}g /g Pu concentration showed a DF of 5 for F and a DF of 35 for Cl across the combined precipitation-filtration-calcination process steps.

  16. Spectroscopy research on the Guizhou Xingyi gangue of different calcined temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, B.; Sun, Y.; Xie, C. [Guizhou University, Guiyang (China). School of Science

    2008-09-15

    The major components, the decomposition mechanisms and the optimum calcination temperature of gangue at different temperatures were studied by XRF, XRD and FTIR. XRF shows that the primary chemical constituents of gangue are SiO{sub 2}, Al{sub 2}O{sub 3}, Fe{sub 2}O{sub 3} and so on. Moreover, the ignition loss is relatively high. XRD shows that the main mineral components of gangue are kaolinite, mica, spathic iron, iron pyrites, rutile, bischofite, quartz and calcite. XRD and FTIR at different calcination temperatures show that kaolinite and mica take part in a dehydration reaction as the temperatures increases. The amounts of SiO{sub 2} and Al{sub 2}O{sub 3}are increased, so the activity of gangue increases. At temperatures above 800{sup o}C, SiO{sub 2} reacts with Al{sub 2}O{sub 3} to produce andalusite, so the activity of the gangue decreases. Based on the experimental results, the optimum calcination temperature of the gangue from Guizhou Xingyi is 700 {sup o}C. 9 refs., 2 figs., 1 tab.

  17. Fuel nitrogen conversion and release of nitrogen oxides during coal gangue calcination.

    Science.gov (United States)

    Zhang, Yingyi; Ge, Xinlei; Liu, Lili; Wang, Xidong; Zhang, Zuotai

    2015-05-01

    The pollution emission during the widespread utilization of coal gangue in construction industry has long been neglected. In present study, the NO x release behaviors in a simulation experiment of coal gangue calcination in construction industry were systematically investigated. The corresponding evolution of nitrogen functionalities in coal gangue was also discussed. Results showed that pyrrolic (N-5) and pyridine N-oxide (N-6-O) forms nitrogen were relatively abundant in the raw gangue. During calcination, the N-5 and N-6-O form nitrogen greatly decreased and converted to quaternary nitrogen (N-Q). It was found that NO2 was formed under slowly heating-up condition and at 600 °C under isothermal condition, while only NO was detected with further increase of temperature. From 600 to 1000 °C, the conversion ratio of fuel nitrogen to NO x increased from 8 to 12 %. The char nitrogen was found greatly contribute to NO formation, which may bring difficulty to the abatement of NO x emission during coal gangue calcination. PMID:25501860

  18. Effect of calcination temperature on the synthesis of potassium titanate with platy morphology

    International Nuclear Information System (INIS)

    The dramatic increases in the number of pneumoconiosis cases have stimulated the search of new materials for replacement of asbestos fibers. Titanate plates with formula AyTi2-xMxO4, where A = K, Rb, Cs and M = Li, Mg, Co, Ni, Cu, Zn, Mn (III), Fe (III) have been studied as an alternative for the use of fibers. The effect of the variation of calcination temperature on the reaction of K2CO3-TiO2-Mg(OH)2 system was studied with the aim of understanding the relationship of this parameter with the morphology and symmetry of the obtained plates. For this study the samples were calcined for 5 hours at temperatures of 950°C, 1000°C, 1050°C and 1100°C. The powders were analyzed by X-ray diffraction and scanning electron microscopy. It was concluded that 1000°C is the better calcination temperature for obtaining more symmetric plates with smaller particle size dispersion. (author)

  19. Test plan for radioactive testing of a vertical direct denitration calciner

    International Nuclear Information System (INIS)

    The prototype Vertical Denitration Calciner (VDC) is installed in glovebox 188 in the Plutonium Process Support Laboratory (PPSL). Safety analysis contained in WHC-SD-CP-SAR-021 (FSAR) Rev. 0-L and Addendum to WHC-SD-CP-SAR-021, ''Laboratory Prototype Calciner'' establishes the prototype VDC needs to be shut down if a seismic event of greater than 0.07 g occurs. Shut down is to be automatic upon detection of the seismic event. This requires tie-in of various valves and power for the prototype VDC into the existing Seismic Shutdown System for the Ventilation Supply Fans described in FSAR 5.4.1.2.4. The proposed changes covered by this USQ evaluation include: (1) the physical tie-in modifications, including drawings and Engineering Change Notice (ECN), (2) the work package for accomplishing the modifications, (3) the changes to the System Description Documents, (4) the changes to the Safety Equipment List necessitated by the modifications, and (5) the changes to the failure modes and effects analysis. WHC-SDCP-OSR-010, Plutonium Finishing Plant Operational Safety Requirements Limiting Condition for Operation (LCO) 3.2.3 has been revised to include the requirement for the existing seismic shutdown system to also shut down the laboratory calciner in the event of detection of a greater than 0.07 g seismic event

  20. Test Plan for Radioactive Testing of a Vertical Direct Denitration Calciner

    International Nuclear Information System (INIS)

    The prototype Vertical Denitration Calciner (VDC) is installed in glovebox 188 in the Plutonium Process Support Laboratory (PPSL). Safety analysis contained in WHC-SD-CP-SAR-021 (FSAR) Rev. 0-L and Addendum to WHC-SD-CP-SAR-021, ''Laboratory Prototype Calciner'' establishes the prototype VDC needs to be shut down if a seismic event of greater than 0.07 g occurs. Shut down is to be automatic upon detection of the seismic event. This requires tie-in of various valves and power for the prototype VDC into the existing Seismic Shutdown System for the Ventilation Supply Fans described in FSAR 5.4.1.2.4. The proposed changes covered by this USQ evaluation include: (1) the physical tie-in modifications, including drawings and Engineering Change Notice (ECN), (2) the work package for accomplishing the modifications, (3) the changes to the System Description Documents, (4) the changes to the Safety Equipment List necessitated by the modifications, and (5) the changes to the failure modes and effects analysis. WHC-SDCP-OSR-010, Plutonium Finishing Plant Operational Safety Requirements Limiting Condition for Operation (LCO) 3.2.3 has been revised to include the requirement for the existing seismic shutdown system to also shut down the laboratory calciner in the event of detection of a greater than 0.07 g seismic event

  1. Silicon Polymer Encapsulation of High Level Calcine Waste for Transportation or Disposal

    International Nuclear Information System (INIS)

    Engineers at the Idaho National Engineering and Environmental Laboratory (INEEL) are investigating the use of a proprietary silicon-polymer to encapsulate high-level calcine waste stored at the INEEL's Idaho Nuclear Technology and Engineering Center (INTEC). The silicon-polymer-encapsulated waste may be suitable for direct disposal at a radioactive waste disposal facility or for transport to an offsite melter for further processing. In connection with silicon-polymer encapsulation, the University of Akron, under special arrangement with Orbit Technologies, the originator of the Polymer Encapsulation Technology (PET), has studied a simulated waste material from INTEC called pilot-scale calcine that contains hazardous materials but no radioactive isotopes. In this study, Toxicity Characteristic Leaching Procedure (TCLP) and Materials Characterization Center Test 1P were performed to test the waste form for disposal. In addition, a maximum waste loading was established for transporting the calcine waste at INTEC to an offsite melter. For this maximum waste loading, compressive strength testing, 10-m drop testing, melt testing, and a Department of Transportation (DOT) oxidizer test were performed

  2. Holographic characterization of protein aggregates

    Science.gov (United States)

    Wang, Chen; Zhong, Xiao; Ruffner, David; Stutt, Alexandra; Philips, Laura; Ward, Michael; Grier, David

    Holographic characterization directly measures the size distribution of subvisible protein aggregates in suspension and offers insights into their morphology. Based on holographic video microscopy, this analytical technique records and interprets holograms of individual aggregates in protein solutions as they flow down a microfluidic channel, without requiring labeling or other exceptional sample preparation. The hologram of an individual protein aggregate is analyzed in real time with the Lorenz-Mie theory of light scattering to measure that aggregate's size and optical properties. Detecting, counting and characterizing subvisible aggregates proceeds fast enough for time-resolved studies, and lends itself to tracking trends in protein aggregation arising from changing environmental factors. No other analytical technique provides such a wealth of particle-resolved characterization data in situ. Holographic characterization promises accelerated development of therapeutic protein formulations, improved process control during manufacturing, and streamlined quality assurance during storage and at the point of use. Mrsec and MRI program of the NSF, Spheryx Inc.

  3. Biomimetic Dye Aggregate Solar Cells

    OpenAIRE

    Marek, Peter L.

    2012-01-01

    A biomimetic self-assembling dye, which forms aggregates that mimic the natural light-harvesting system of special photosynthetic active bacteria, has been investigated towards its applicability to solar cells. This fully synthetic dye, self-assembles to orderly structured nano- to micrometer sized rod-shaped aggregates, which might improve solar cells based on conventional organic dyes. In order to use the full potential of the dye aggregates, the self-assembly needed to be controlled and a ...

  4. Aggregation in Large Dynamic Panels

    OpenAIRE

    Pesaran, Mohammad Hashem; Chudik, Alexander

    2011-01-01

    This paper considers the problem of aggregation in the case of large linear dynamic panels, where each micro unit is potentially related to all other micro units, and where micro innovations are allowed to be cross sectionally dependent. Following Pesaran (2003), an optimal aggregate function is derived, and the limiting behavior of the aggregation error is investigated as N (the number of cross section units) increases. Certain distributional features of micro parameters are also identi...

  5. Modifiers of mutant huntingtin aggregation

    OpenAIRE

    Teuling, Eva; Bourgonje, Annika; Veenje, Sven; Thijssen, Karen; Boer, Jelle de; van der Velde, Joeri; Swertz, Morris; Nollen, Ellen

    2011-01-01

    Protein aggregation is a common hallmark of a number of age-related neurodegenerative diseases, including Alzheimer’s, Parkinson’s, and polyglutamine-expansion disorders such as Huntington’s disease, but how aggregation-prone proteins lead to pathology is not known. Using a genome-wide RNAi screen in a C. elegans-model for polyglutamine aggregation, we previously identified 186 genes that suppress aggregation. Using an RNAi screen for human orthologs of these genes, we here present 26 human g...

  6. Aggregation dynamics of rigid polyelectrolytes

    Science.gov (United States)

    Tom, Anvy Moly; Rajesh, R.; Vemparala, Satyavani

    2016-01-01

    Similarly charged polyelectrolytes are known to attract each other and aggregate into bundles when the charge density of the polymers exceeds a critical value that depends on the valency of the counterions. The dynamics of aggregation of such rigid polyelectrolytes are studied using large scale molecular dynamics simulations. We find that the morphology of the aggregates depends on the value of the charge density of the polymers. For values close to the critical value, the shape of the aggregates is cylindrical with height equal to the length of a single polyelectrolyte chain. However, for larger values of charge, the linear extent of the aggregates increases as more and more polymers aggregate. In both the cases, we show that the number of aggregates decrease with time as power laws with exponents that are not numerically distinguishable from each other and are independent of charge density of the polymers, valency of the counterions, density, and length of the polyelectrolyte chain. We model the aggregation dynamics using the Smoluchowski coagulation equation with kernels determined from the molecular dynamics simulations and justify the numerically obtained value of the exponent. Our results suggest that once counterions condense, effective interactions between polyelectrolyte chains short-ranged and the aggregation of polyelectrolytes are diffusion-limited.

  7. Novel aspects of platelet aggregation

    Directory of Open Access Journals (Sweden)

    Roka-Moya Y. M.

    2014-01-01

    Full Text Available The platelet aggregation is an important process, which is critical for the hemostatic plug formation and thrombosis. Recent studies have shown that the platelet aggregation is more complex and dynamic than it was previously thought. There are several mechanisms that can initiate the platelet aggregation and each of them operates under specific conditions in vivo. At the same time, the influence of certain plasma proteins on this process should be considered. This review intends to summarize the recent data concerning the adhesive molecules and their receptors, which provide the platelet aggregation under different conditions.

  8. Platelet aggregation following trauma

    DEFF Research Database (Denmark)

    Windeløv, Nis A; Sørensen, Anne M; Perner, Anders;

    2014-01-01

    We aimed to elucidate platelet function in trauma patients, as it is pivotal for hemostasis yet remains scarcely investigated in this population. We conducted a prospective observational study of platelet aggregation capacity in 213 adult trauma patients on admission to an emergency department (ED......). Inclusion criteria were trauma team activation and arterial cannula insertion on arrival. Blood samples were analyzed by multiple electrode aggregometry initiated by thrombin receptor agonist peptide 6 (TRAP) or collagen using a Multiplate device. Blood was sampled median 65 min after injury; median injury...... severity score (ISS) was 17; 14 (7%) patients received 10 or more units of red blood cells in the ED (massive transfusion); 24 (11%) patients died within 28 days of trauma: 17 due to cerebral injuries, four due to exsanguination, and three from other causes. No significant association was found between...

  9. Fractal Aggregation Under Rotation

    Institute of Scientific and Technical Information of China (English)

    WUFeng-Min; WULi-Li; LUHang-Jun; LIQiao-Wen; YEGao-Xiang

    2004-01-01

    By means of the Monte Carlo simulation, a fractal growth model is introduced to describe diffusion-limited aggregation (DLA) under rotation. Patterns which are different from the classical DLA model are observed and the fractal dimension of such clusters is calculated. It is found that the pattern of the clusters and their fractal dimension depend strongly on the rotation velocity of the diffusing particle. Our results indicate the transition from fractal to non-fractal behavior of growing cluster with increasing rotation velocity, i.e. for small enough angular velocity ω; thefractal dimension decreases with increasing ω;, but then, with increasing rotation velocity, the fractal dimension increases and the cluster becomes compact and tends to non-fractal.

  10. Fractal Aggregation Under Rotation

    Institute of Scientific and Technical Information of China (English)

    WU Feng-Min; WU Li-Li; LU Hang-Jun; LI Qiao-Wen; YE Gao-Xiang

    2004-01-01

    By means of the Monte Carlo simulation, a fractal growth model is introduced to describe diffusion-limited aggregation (DLA) under rotation. Patterns which are different from the classical DLA model are observed and the fractal dimension of such clusters is calculated. It is found that the pattern of the clusters and their fractal dimension depend strongly on the rotation velocity of the diffusing particle. Our results indicate the transition from fractal to non-fractal behavior of growing cluster with increasing rotation velocity, i.e. for small enough angular velocity ω the fractal dimension decreases with increasing ω, but then, with increasing rotation velocity, the fractal dimension increases and the cluster becomes compact and tends to non-fractal.

  11. Extended Development Work to Validate a HLW Calcine Waste Form via INL's Cold Crucible Induction Melter

    International Nuclear Information System (INIS)

    To accomplish calcine treatment objectives, the Idaho Clean-up Project contractor, CWI, has chosen to immobilize the calcine in a glass-ceramic via the use of a Hot-Isostatic-Press (HIP); a treatment selection formally documented in a 2010 Record of Decision (ROD). Even though the HIP process may prove suitable for the calcine as specified in the ROD and validated in a number of past value engineering sessions, DOE is evaluating back-up treatment methods for the calcine as a result of the technical, schedule, and cost risk associated with the HIPing process. Consequently DOE HQ has requested DOE ID to make INL's bench-scale cold-crucible induction melter (CCIM) available for investigating its viability as a process alternate to calcine treatment. The waste form is the key component of immobilization of radioactive waste. Providing a solid, stable, and durable material that can be easily be stored is the rationale for immobilization of radioactive waste material in glass, ceramic, or glass-ceramics. Ceramic waste forms offer an alternative to traditional borosilicate glass waste forms. Ceramics can usually accommodate higher waste loadings than borosilicate glass, leading to smaller intermediate and long-term storage facilities. Many ceramic phases are known to possess superior chemical durability as compared to borosilicate glass. However, ceramics are generally multiphase systems containing many minor phase that make characterization and prediction of performance within a repository challenging. Additionally, the technologies employed in ceramic manufacture are typically more complex and expensive. Thus, many have proposed using glass-ceramics as compromise between in the more inexpensive, easier to characterize glass waste forms and the more durable ceramic waste forms. Glass-ceramics have several advantages over traditional borosilicate glasses as a waste form. Borosilicate glasses can inadvertently devitrify, leading to a less durable product that could crack

  12. Improvement of the crystallinity and photocatalytic property of zinc oxide as calcination product of Zn-Al layered double hydroxide

    Energy Technology Data Exchange (ETDEWEB)

    Ahmed, Abdullah Ahmed Ali [Department of Physics, Faculty of Science, Universiti Putra Malaysia, 43400 UPM Serdang, Selangor (Malaysia); Talib, Zainal Abidin, E-mail: zainalat@science.upm.edu.my [Department of Physics, Faculty of Science, Universiti Putra Malaysia, 43400 UPM Serdang, Selangor (Malaysia); Hussein, Mohd Zobir bin [Department of Chemistry, Faculty of Science, Universiti Putra Malaysia, 43400 UPM Serdang, Selangor (Malaysia); Advanced Materials and Nanotechnology Laboratory, Institute of Advanced Technology (ITMA), Universiti Putra Malaysia, 43400 UPM Serdang, Selangor (Malaysia); Zakaria, Azmi [Department of Physics, Faculty of Science, Universiti Putra Malaysia, 43400 UPM Serdang, Selangor (Malaysia); Advanced Materials and Nanotechnology Laboratory, Institute of Advanced Technology (ITMA), Universiti Putra Malaysia, 43400 UPM Serdang, Selangor (Malaysia)

    2012-10-25

    Highlights: Black-Right-Pointing-Pointer ZnO phase and ZnAl{sub 2}O{sub 4} spinel can be formed as Zn-Al-NO{sub 3}-LDH calcination products. Black-Right-Pointing-Pointer The crystallinity of ZnO phase increased with an increase of calcination temperature. Black-Right-Pointing-Pointer The optical band gaps of ZnO were improved with an increase in temperature. Black-Right-Pointing-Pointer The oxygen vacancies in ZnO and ZnAl{sub 2}O{sub 4} generated the ESR signals. - Abstract: Zinc oxide with different degrees of crystallinity can be formed as Zn-Al-layered double hydroxide (Zn-Al-NO{sub 3}-LDH) calcination products. ZnAl{sub 2}O{sub 4} spinel is also formed in a range of calcination temperatures from 600 to 1000 Degree-Sign C from the LDH. X-ray diffraction patterns showed that the crystallinity of the ZnO phase increased as calcination temperatures increased. The LDH structure was fully collapsed at and above 400 Degree-Sign C. The photocatalytic activity was determined by UV-VIS-NIR diffuse reflectance spectroscopy. The band gap of the calcined samples increased as the calcination temperature increased. Electron spin resonance (ESR) spectra of the fresh and calcined LDH at room temperature demonstrated that oxygen vacancies in the ZnO and ZnAl{sub 2}O{sub 4} were responsible for the generation of ESR signals. One BET specific surface area increased from 1 m{sup 2}/g for the LDH to a maximum at 400 Degree-Sign C (43 m{sup 2}/g) and decreased thereafter down to 6 m{sup 2}/g at 1000 Degree-Sign C.

  13. 4.2. The kinetics of nitric acid decomposition of calcined borosilicate raw material of Ak-Arkhar Deposit

    International Nuclear Information System (INIS)

    Present article is devoted to kinetics of nitric acid decomposition of calcined borosilicate raw material of Ak-Arkhar Deposit. The dependence of nitric acid decomposition of calcined boric raw material for extraction of boron oxide on temperature (20-100 deg C) and process duration (15-60 minutes) was defined. It was defined that at temperature increasing the extraction rate of boron oxide increases from 20.8 to 78.6%.

  14. Analysis of the reusability of the energy of the exhaust gas from the calciner for the production of carbon

    International Nuclear Information System (INIS)

    A calciner is used to produce carbon from anthracite coal. In its working process, a significant amount of energy is lost through its exhaust gas. How much energy can be recovered from the exhaust gas becomes important. To answer this question a method to determine the mass flow rate and the composition of the exhaust gas from a calciner is developed, and a combustion model based on well-stirred reactor is used to obtain the suitable combustor parameters and the amount of the chemical energy which can be released in combustion. As an example to verify the method and the model, the energy utilization ratio of a calciner with power of 1250 kW is investigated. The results show that the method can determine the mass flow rate and the composition of the exhaust gas, and the combustion model is suitable for obtaining reasonable results in determining the volume and the heat duty of the combustor, the air–fuel ratio, and the amount of the chemical energy released. For a calciner with power of 1250 kW, when the temperature of the tail gas after combustion reaches to 135 °C, the energy utilization ratio of the calciner is calculated to be around 77%. - Highlights: • A method obtaining the mass balance of exhaust gas from calciner is reported. • A combustion model obtaining combustion behavior of the exhaust gas is reported. • Determining the energy utilization ratio of a typical calciner is demonstrated. • The energy utilization ratio of a typical calciner is about 77%

  15. Chemical and mineralogical modifications of simplified radioactive waste calcine during heat treatment

    Energy Technology Data Exchange (ETDEWEB)

    Monteiro, A. [CEA, DEN, DTCD/SECM/LDMC Marcoule, BP 17171, F-30207 Bagnols-sur-Cèze cedex (France); Schuller, S., E-mail: sophie.schuller@cea.fr [CEA, DEN, DTCD/SECM/LDMC Marcoule, BP 17171, F-30207 Bagnols-sur-Cèze cedex (France); Toplis, M.J. [CNRS, Observatoire Midi Pyrénées, IRAP (UMR 5277), F-31400 Toulouse (France); Podor, R.; Ravaux, J.; Clavier, N.; Brau, H.P. [ICSM UMR 5257 CEA/CNRS/UMR/ENSCM Site de Marcoule, BP 17171, F-30207 Bagnols-sur-Cèze cedex (France); Charpentier, T. [UMR CEA/CNRS 3299, IRAMIS, SIS2M, LSDRM Saclay, F-91191 Gif-sur-Yvette cedex (France); Angeli, F. [CEA, DEN, DTCD/SECM/LCLT Marcoule, BP 17171, F-30207 Bagnols-sur-Cèze cedex (France); Leterrier, N. [CEA, DEN, DM2S/SFME/LSFT Saclay, F-91191 Gif-sur-Yvette cedex (France)

    2014-05-01

    The microstructural and mineralogical changes associated with heating calcined mixtures of Al(NO{sub 3}){sub 3}⋅9H{sub 2}O–NaNO{sub 3} have been studied. This system is a simplified analogue of high-level radioactive waste calcine, one of the raw materials used in the vitrification process employed for waste management. The decomposition (dehydration and denitration) and formation of secondary crystalline phases have been studied by differential thermal and gravimetric analysis (DTA and TGA), and heat-treated products characterized by X-ray diffraction, Raman spectroscopy, Nuclear Magnetic Resonance (NMR) and Transmission Electron Microscopy (TEM). It is found that pure Al(NO{sub 3}){sub 3}⋅9H{sub 2}O transforms to amorphous Al{sub 2}O{sub 3} at a temperature of ∼180 °C, well below that of the calcination process (500 °C). This amorphous Al{sub 2}O{sub 3} is highly porous with a high specific surface area, but may in turn convert to denser γ-Al{sub 2}O{sub 3} and α-Al{sub 2}O{sub 3} with increasing temperature. On the other hand, pure NaNO{sub 3} remains stable up to ∼880 °C, despite a solid–liquid transition at ∼320 °C. For Al(NO{sub 3}){sub 3}⋅9H{sub 2}O–NaNO{sub 3} mixtures, the products of calcination at 500 °C are found to consist of very fine porous material containing Na, Al and O, in addition to a variable proportion of well-defined crystals consisting of Na, and O. Heating these mixtures to temperatures of up to 1000 °C shows that for the case 80% Al(NO{sub 3}){sub 3}⋅9H{sub 2}O −20% NaNO{sub 3} (weight%) a variety of crystalline sodium aluminates is formed (NaAlO{sub 2}, NaAl{sub 11}O{sub 17}, NaAl{sub 6}O{sub 9.5}), while for the 50–50 mixture, only NaAlO{sub 2} is found. In large amounts, addition of alumina thus leads to the formation of crystalline phases rich in Al{sub 2}O{sub 3} that are responsible for hardening the calcine as the temperature rises. The kinetics of nitrogen loss from NaNO{sub 3} are also found to be

  16. Research on Judgment Aggregation Based on Logic

    OpenAIRE

    Li Dai; Jihua Zhang

    2014-01-01

    Preference aggregation and judgment aggregation are two basic research models of group decision making. And preference aggregation has been deeply studied in social choice theory. However, researches of social choice theory gradually focus on judgment aggregation which appears recently. Judgment aggregation focuses on how to aggregate many consistent logical formulas into one, from the perspective of logic. We try to start with judgment aggregation model based on logic and then explore differ...

  17. Effect of calcination temperature on structural properties and photocatalytic activity of Mn-C-codoped TiO2

    International Nuclear Information System (INIS)

    Mn-C-codoped TiO2 catalysts were synthesized by modified sol-gel method based on the self-assembly technique using polyoxyethylene sorbitan monooleate (Tween 80) as template and carbon precursor and the effect of calcination temperature on their structural properties and photocatalytic activity were investigated. The XRD results showed undoped and Mn-C-codoped TiO2 calcined at 400 deg C only include anatase phase and the rutile phase appears when the calcination temperature reached to 600 deg C. UV-vis absorption spectroscopy demonstrates that the absorption spectra are strongly modified by the calcination temperature. Moreover, the Mn-C-TiO2 calcined at 400 deg C showed the lowest PL intensity due to a decrease in the recombination rate of photogenerated electrons and holes under light irradiation. The photocatalytic activity of Mn-C-codoped TiO2 were evaluated by the degradation of methyl orange (MO) under the simulate daylight irradiation and all the prepared Mn-C-codoped TiO2 samples exhibited high photocatalytic activities for photocatalytic decolorisation of methyl orange aqueous solution. At 400 deg C, the Mn-C-codoped TiO2 samples showed the highest photocatalytic activity due to synergetic effects of good crystallize ation, appropriate phase composition and slower recombination rate of photogenerated charge carriers, which further confirms the calcination temperature could affect the properties of Mn-C-codoped TiO2 significantly. (author)

  18. Role of Calcination Temperature on the Hydrotalcite Derived MgO–Al2O3 in Converting Ethanol to Butanol

    Energy Technology Data Exchange (ETDEWEB)

    Ramasamy, Karthikeyan K. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States). Chemical and Biological Process Development Group and Inst. for Integrated Catalysis; Gray, Michel [Pacific Northwest National Lab. (PNNL), Richland, WA (United States). Chemical and Biological Process Development Group; Job, Heather [Pacific Northwest National Lab. (PNNL), Richland, WA (United States). Chemical and Biological Process Development Group; Santosa, Daniel [Pacific Northwest National Lab. (PNNL), Richland, WA (United States). Chemical and Biological Process Development Group; Li, Xiaohong Shari [Pacific Northwest National Lab. (PNNL), Richland, WA (United States). Inst. for Integrated Catalysis; Devaraj, Arun [Pacific Northwest National Lab. (PNNL), Richland, WA (United States). Environmental Molecular Sciences Lab. (EMSL); Karkamkar, Abhi [Pacific Northwest National Lab. (PNNL), Richland, WA (United States). Chemical and Biological Process Development Group; Wang, Yong [Pacific Northwest National Lab. (PNNL), Richland, WA (United States). Chemical and Biological Process Development Group and Inst. for Integrated Catalysis; ; Washington State Univ., Pullman, WA (United States)

    2015-10-09

    In the base catalyzed ethanol condensation reactions, the calcined MgO-Al2O3 derived hydrotalcites used broadly as catalytic material and the calcination temperature plays a big role in determining the catalytic activity. The characteristic of the hydrotalcite material treated between catalytically relevant temperatures 450ºC and 800ºC have been studied with respect to the physical, chemical, and structural properties and compared with catalytic activity testing. With the increasing calcination temperature, the total measured catalytic basicity dropped linearly with the calcination temperature and the total measured acidity stayed the same for all the calcination temperatures except 800ºC. However, the catalyst activity testing does not show any direct correlation between the measured catalytic basicity and the catalyst activity to the ethanol condensation reaction to form 1-butanol. The highest ethanol conversion of 44 percent with 1-butanol selectivity of 50 percent was achieved for the 600ºC calcined hydrotalcite material.

  19. The variation of cationic microstructure in Mn-doped spinel ferrite during calcination and its effect on formaldehyde catalytic oxidation.

    Science.gov (United States)

    Liang, Xiaoliang; Liu, Peng; He, Hongping; Wei, Gaoling; Chen, Tianhu; Tan, Wei; Tan, Fuding; Zhu, Jianxi; Zhu, Runliang

    2016-04-01

    In this study, a series of Mn substituted spinel ferrites calcinated at different temperatures were used as catalysts for the oxidation of formaldehyde (HCHO). X-ray diffraction, Raman spectroscopy, X-ray photoelectron spectroscopy and H2 temperature-programmed reduction were conducted to characterize the structure and physico-chemical properties of catalysts, which were affected by calcination in the range of 200-600°C. Results show that all the ferrites were with spinel structure, and those calcinated in the range of 300-600°C were in the phase of maghemite. The calcination changed the valence and distribution of Mn and Fe on the ferrite surface, and accordingly the reducibility of ferrites. The HCHO catalytic oxidation test showed that with the increase of calcination temperature, the activity was initially improved until 400°C, but then decreased. The variation of HCHO conversion performance was well positively correlated to the variation of reduction temperature of surface Mn(4+) species. The remarkable effect of calcination on the catalytic activity of Mn-doped spinel ferrites for HCHO oxidation was discussed in view of reaction mechanism and variations in cationic microstructure of Mn-doped ferrites. PMID:26774985

  20. Effect of calcination temperature on structural properties and photocatalytic activity of Mn-C-codoped TiO{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Cai, Jianbo; Xin, Wei; Liu, Guanglong; Lin, Die; Zhu, Duanwei, E-mail: liugl@mail.hzau.edu.cn [Laboratory of Eco-Environmental Engineering Research, College of Resources and Environment, Huazhong Agricultural University (HZAU), Wuhan (China)

    2016-03-15

    Mn-C-codoped TiO{sub 2} catalysts were synthesized by modified sol-gel method based on the self-assembly technique using polyoxyethylene sorbitan monooleate (Tween 80) as template and carbon precursor and the effect of calcination temperature on their structural properties and photocatalytic activity were investigated. The XRD results showed undoped and Mn-C-codoped TiO{sub 2} calcined at 400 deg C only include anatase phase and the rutile phase appears when the calcination temperature reached to 600 deg C. UV-vis absorption spectroscopy demonstrates that the absorption spectra are strongly modified by the calcination temperature. Moreover, the Mn-C-TiO{sub 2} calcined at 400 deg C showed the lowest PL intensity due to a decrease in the recombination rate of photogenerated electrons and holes under light irradiation. The photocatalytic activity of Mn-C-codoped TiO{sub 2} were evaluated by the degradation of methyl orange (MO) under the simulate daylight irradiation and all the prepared Mn-C-codoped TiO{sub 2} samples exhibited high photocatalytic activities for photocatalytic decolorisation of methyl orange aqueous solution. At 400 deg C, the Mn-C-codoped TiO{sub 2} samples showed the highest photocatalytic activity due to synergetic effects of good crystallize ation, appropriate phase composition and slower recombination rate of photogenerated charge carriers, which further confirms the calcination temperature could affect the properties of Mn-C-codoped TiO2 significantly. (author)

  1. Topics in Probabilistic Judgment Aggregation

    Science.gov (United States)

    Wang, Guanchun

    2011-01-01

    This dissertation is a compilation of several studies that are united by their relevance to probabilistic judgment aggregation. In the face of complex and uncertain events, panels of judges are frequently consulted to provide probabilistic forecasts, and aggregation of such estimates in groups often yield better results than could have been made…

  2. J-aggregates, v.2

    CERN Document Server

    Kobayashi, Takayoshi

    2012-01-01

    This work deals with J-aggregates, which have a long history of research. The volume covers electronic states, linear and nonlinear optical properties. Various properties and processes of J-aggregates, such as super-radiance, excitons, photon echo, geometrical structure, electron transfer and femtosecond spectroscopy, are discussed.

  3. Molecular aggregation of humic substances

    Science.gov (United States)

    Wershaw, R. L.

    1999-01-01

    Humic substances (HS) form molecular aggregates in solution and on mineral surfaces. Elucidation of the mechanism of formation of these aggregates is important for an understanding of the interactions of HS in soils arid natural waters. The HS are formed mainly by enzymatic depolymerization and oxidation of plant biopolymers. These reactions transform the aromatic and lipid plant components into amphiphilic molecules, that is, molecules that consist of separate hydrophobic (nonpolar) and hydrophilic (polar) parts. The nonpolar parts of the molecules are composed of relatively unaltered segments of plant polymers and the polar parts of carboxylic acid groups. These amphiphiles form membrane-like aggregates on mineral surfaces and micelle-like aggregates in solution. The exterior surfaces of these aggregates are hydrophilic, and the interiors constitute separate hydrophobic liquid-like phases.

  4. Immunogenicity of Therapeutic Protein Aggregates.

    Science.gov (United States)

    Moussa, Ehab M; Panchal, Jainik P; Moorthy, Balakrishnan S; Blum, Janice S; Joubert, Marisa K; Narhi, Linda O; Topp, Elizabeth M

    2016-02-01

    Therapeutic proteins have a propensity for aggregation during manufacturing, shipping, and storage. The presence of aggregates in protein drug products can induce adverse immune responses in patients that may affect safety and efficacy, and so it is of concern to both manufacturers and regulatory agencies. In this vein, there is a lack of understanding of the physicochemical determinants of immunological responses and a lack of standardized analytical methods to survey the molecular properties of aggregates associated with immune activation. In this review, we provide an overview of the basic immune mechanisms in the context of interactions with protein aggregates. We then critically examine the literature with emphasis on the underlying immune mechanisms as they relate to aggregate properties. Finally, we highlight the gaps in our current understanding of this issue and offer recommendations for future research. PMID:26869409

  5. DRAG ON SUBMICRON NANOPARTICLE AGGREGATES

    Institute of Scientific and Technical Information of China (English)

    F.; Einar; Kruis

    2005-01-01

    A new procedure was developed for estimating the effective collision diameter of an aggregate composed of primary particles of any size. The coagulation coefficient of two oppositely charged particles was measured experimentally and compared with classic Fuchs theory, including a new method to account for particle non-sphericity. A second set of experiments were performed on well-defined nanoparticle aggregates at different stages of sintering, i.e. from the aggregate to the fully sintered stage. Here, electrical mobility was used to characterize the particle drag. The aggregates are being built from two different size-fractionated nanoparticle aerosols, the non-aggregated particles are discarded by an electrofilter and then they are passed through a furnace at concentrations low enough not to induce coagulation.

  6. Mechanics of fire ant aggregations

    Science.gov (United States)

    Tennenbaum, Michael; Liu, Zhongyang; Hu, David; Fernandez-Nieves, Alberto

    2016-01-01

    Fire ants link their bodies to form aggregations; these can adopt a variety of structures, they can drip and spread, or withstand applied loads. Here, by using oscillatory rheology, we show that fire ant aggregations are viscoelastic. We find that, at the lowest ant densities probed and in the linear regime, the elastic and viscous moduli are essentially identical over the spanned frequency range, which highlights the absence of a dominant mode of structural relaxation. As ant density increases, the elastic modulus rises, which we interpret by alluding to ant crowding and subsequent jamming. When deformed beyond the linear regime, the aggregation flows, exhibiting shear-thinning behaviour with a stress load that is comparable to the maximum load the aggregation can withstand before individual ants are torn apart. Our findings illustrate the rich, collective mechanical behaviour that can arise in aggregations of active, interacting building blocks.

  7. Erythrocyte aggregation in flowing blood

    International Nuclear Information System (INIS)

    This paper addresses the issue of whether nonionic contrast media (CM) promote thrombosis by the formation of large, irregular red blood cell aggregates with videomicroscopy and a flow chamber, red blood cell aggregates adjacent to an endothelial cell monolayer were imaged at 17 sec-1 in dilute suspensions (hematocrit, --8) at 370C in plasma with 20% CM by non-red blood cell volume. All aggregates were rouleaux (<100 μm) readily dispersed at higher shear rates. Aggregate length in eight experiments was increased 11% by ioxaglate (320 mg of iodine per milliliter), decreased 58% by diatrizoate (370 mg of iodine per milliliter) but reduced similarly (16%) by iohexol (350 mg of iodine per milliliter) and saline. Iohexol did not enhance platelet aggregation on injured monolayers

  8. RankAggreg, an R package for weighted rank aggregation

    Directory of Open Access Journals (Sweden)

    Datta Susmita

    2009-02-01

    Full Text Available Abstract Background Researchers in the field of bioinformatics often face a challenge of combining several ordered lists in a proper and efficient manner. Rank aggregation techniques offer a general and flexible framework that allows one to objectively perform the necessary aggregation. With the rapid growth of high-throughput genomic and proteomic studies, the potential utility of rank aggregation in the context of meta-analysis becomes even more apparent. One of the major strengths of rank-based aggregation is the ability to combine lists coming from different sources and platforms, for example different microarray chips, which may or may not be directly comparable otherwise. Results The RankAggreg package provides two methods for combining the ordered lists: the Cross-Entropy method and the Genetic Algorithm. Two examples of rank aggregation using the package are given in the manuscript: one in the context of clustering based on gene expression, and the other one in the context of meta-analysis of prostate cancer microarray experiments. Conclusion The two examples described in the manuscript clearly show the utility of the RankAggreg package in the current bioinformatics context where ordered lists are routinely produced as a result of modern high-throughput technologies.

  9. Perspectives on Preference Aggregation.

    Science.gov (United States)

    Regenwetter, Michel

    2009-07-01

    For centuries, the mathematical aggregation of preferences by groups, organizations, or society itself has received keen interdisciplinary attention. Extensive theoretical work in economics and political science throughout the second half of the 20th century has highlighted the idea that competing notions of rational social choice intrinsically contradict each other. This has led some researchers to consider coherent democratic decision making to be a mathematical impossibility. Recent empirical work in psychology qualifies that view. This nontechnical review sketches a quantitative research paradigm for the behavioral investigation of mathematical social choice rules on real ballots, experimental choices, or attitudinal survey data. The article poses a series of open questions. Some classical work sometimes makes assumptions about voter preferences that are descriptively invalid. Do such technical assumptions lead the theory astray? How can empirical work inform the formulation of meaningful theoretical primitives? Classical "impossibility results" leverage the fact that certain desirable mathematical properties logically cannot hold in all conceivable electorates. Do these properties nonetheless hold true in empirical distributions of preferences? Will future behavioral analyses continue to contradict the expectations of established theory? Under what conditions do competing consensus methods yield identical outcomes and why do they do so? PMID:26158988

  10. Physical, Chemical and Structural Evolution of Zeolite - Containing Waste Forms Produced from Metakaolinite and Calcined HLW

    International Nuclear Information System (INIS)

    During the seventh year of the current grant (DE-FG02-05ER63966) we completed an exhaustive study of cold calcination and began work on the development of tank fill materials to fill empty tanks and control residuals. Cold calcination of low and high NOx low activity waste (LAW) SRS Tank 44 and Hanford AN-107 simulants, respectively with metallic Al + Si powders was evaluated. It was found that a combination of Al and Si powders could be used as reducing agents to reduce the nitrate and nitrite content of both low and high NOx LAW to low enough levels to allow the LAW to be solidified directly by mixing it with metakaolin and allowing it to cure at 90 C. During room temperature reactions, NOx was reduced and nitrogen was emitted as N2 or NH3. This was an important finding because now one can pretreat LAW at ambient temperatures which provides a low-temperature alternative to thermal calcination. The significant advantage of using Al and Si metals for denitration/denitrition of the LAW is the fact that the supernate could potentially be treated in situ in the waste tanks themselves. Tank fill materials based upon a hydroceramic binder have been formulated from mixtures of metakaolinite, Class F fly ash and Class C flue gas desulphurization (FGD) ash mixed with various concentrations of NaOH solution. These harden over a period of hours or days depending on composition. A systematic study of properties of the tank fill materials (leachability) and ability to adsorb and hold residuals is under way

  11. Investigation of corrosion experienced in a spray calciner/ceramic melter vitrification system

    International Nuclear Information System (INIS)

    After periodic testing of a large-scale spray calciner/ceramic melter vitrification system over a 2-yr period, sufficient corrosion was noted on various parts of the vitrification system to warrant its disassembly and inspection. A majority of the 316 SS sintered metal filters on the spray calciner were damaged by chemical corrosion and/or high temperature oxidation. Inconel-601 portions of the melter lid were attacked by chlorides and sulfates which volatilized from the molten glass. The refractory blocks, making up the walls of the melter, were attacked by the waste glass. This attack was occurring when operating temperatures were >12000C. The melter floor was protected by a sludge layer and showed no corrosion. Corrosion to the Inconel-690 electrodes was minimal, and no corrosion was noted in the offgas treatment system downstream of the sintered metal filters. It is believed that most of the melter corrosion occurred during one specific operating period when the melter was operated at high temperatures in an attempt to overcome glass foaming behavior. These high temperatures resulted in a significant release of volatile elements from the molten glass, and also created a situation where the glass was very fluid and convective, which increased the corrosion rate of the refractories. Specific corrosion to the calciner components cannot be proven to have occurred during a specific time period, but the mechanisms of attack were all accelerated under the high-temperature conditions that were experienced with the melter. A review of the materials of construction has been made, and it is concluded that with controlled operating conditions and better protection of some materials of construction corrosion of these systems will not cause problems. Other melter systems operating under similar strenuous conditions have shown a service life of 3 yr

  12. PREPARATION AND PROPERTIES OF Co-Fe MIXED OXIDES OBTAINED BY CALCINATION OF LAYERED DOUBLE HYDROXIDES

    Directory of Open Access Journals (Sweden)

    M. E. Pérez Bernal

    2004-12-01

    Full Text Available Solids containing Co(II and Fe(III with molar ratios of 2/1, 3/2, 1/1, 2/3 and 1/2 have been synthetised by coprecipitation at constant pH. All they displayed a hydrotalcite-like structure with interlayer carbonate, which crystallinity decreases as the iron content was increased. No other crystalline phase was identified, even in the Fe-rich samples. They have been characterised by powder X-ray diffraction, FT-IR spectroscopy, thermal analysis (differential thermal analysis, thermogravimetric analysis and temperature-programmed reduction, in addition to specific surface area assessment by nitrogen adsorption at -196°C. A minor oxidation of Co(II to Co(III is observed in the Co-rich samples, although it reverses again to Co(II upon calcination in oxygen at ca. 850°C. Thermal decomposition takes place in a single step up to ca. 350°C, and the specific surface area increases with the iron content, probably because of the presence of hydrated amorphous iron oxides. The solids calcined at 1200°C in air contain crystalline CoO, Co3O4 and CoFe2O4 (spinel, this one being the dominant phase, and only phase detected for large Fe contents. Metallic species are more easily reduced in the original solids than in the calcined ones, and in all cases iron seems to be reduced at a higher temperature than cobalt.

  13. Effect of the rate of calcination of kaolin on the properties of metakaolin-based geopolymers

    OpenAIRE

    B.B. Kenne Diffo; A. Elimbi; Cyr, M; J. Dika Manga; H. Tchakoute Kouamo

    2015-01-01

    Kaolin samples of the same mass were treated at 700 °C for the same duration of 30 min by varying the rate of calcination (1, 2.5, 5, 10, 15 and 20 °C/min) in order to obtain metakaolins which were used to produce geopolymers. Depending on the nature of each type of material, kaolin, metakaolins and geopolymers were characterized using thermal analysis, chemical analysis, XRD, FTIR, particle size distribution, specific surface area, bulk density, setting time and compressive strength. FTIR an...

  14. Effects of Composition and Calcination Temperature on Photocatalytic Evolution over from Glycerol and Water Mixture

    OpenAIRE

    Cancan Fan; Xitao Wang; Fen Wang; Huanxin Sang

    2012-01-01

    A series of sulfide coupled semiconductors supported on SiO2, ( ), was prepared by incipient wet impregnation method. The photocatalysts were characterized by XRD, XPS, TPR, and UV/Vis DRS. Characterization results show that the chemical actions between ZnS and CdS resulted in the formation of solid solutions on the surface of the support and the formation of them is affected by the molar ratio of ZnS/CdS and calcination temperature. Performance of photocatalysts was tested in the home made r...

  15. Structure and pozzolanic activity of calcined coal gangue during the process of mechanical activation

    Energy Technology Data Exchange (ETDEWEB)

    Wei Guo; Dongxu Li; Jianhua Chen; Nanru Yang [Yancheng Institute of Technology, Yancheng (China). Department of Material Engineering

    2009-04-15

    On the basis of analyzing coal gangue's chemical and mineral compositions, the structure change of coal gangue during the mechanical activation was investigated by XRD, FTIR, NMR, and the mechanical strength of the cement doped coal gangue with various specific surface area was tested. The experimental results indicate that the lattice structure of metakaolin in coal gangue samples calcined at 700{sup o}C disorganizes gradually and becomes disordered, and the lattice structure of {alpha}-quartz is distorted slightly. The pozzolanic activity of the coal gangue increases obviously with its structural disorganization.

  16. Vitrification of radioactive high-level waste by spray calcination and in-can melting

    International Nuclear Information System (INIS)

    After several nonradioactive test runs, radioactive waste from the processing of 1.5 t of spent, light-water-reactor fuel was successfully concentrated, dried and converted to a vitreous product. A total of 97 L of waste glass (in two stainless steel canisters) was produced. The spray calcination process coupled to the in-can melting process, as developed at Pacific Northwest Laboratory, was used to vitrify the waste. An effluent system consisting of a variety of condensation of scrubbing steps more than adequately decontaminated the process off gas before it was released to the atmosphere

  17. Development of a SREX flowsheet for the separation of strontium from dissolved INEEL zirconium calcine

    International Nuclear Information System (INIS)

    Laboratory experimentation has indicated that the SREX process is effective for partitioning 90Sr from acidic radioactive waste solutions located at the Idaho Nuclear Technology and Engineering Center. These laboratory results were used to develop a flowsheet for countercurrent testing of the SREX process with dissolved pilot plant calcine. Testing was performed using 24 stages of 2-cm diameter centrifugal contactors which are installed in the Remote Analytical Laboratory hot cell. Dissolved Run No.64 pilot plant calcine spiked with 85Sr was used as feed solution for the testing. The flowsheet tested consisted of an extraction section (0.15 M 4prime,4prime(5prime)-di-(tert-butylcyclohexo)-18-crown-6 and 1.5 M TBP in Isopar-L.), a 1.0 M NaNO3 scrub section to remove extracted K from the SREX solvent, a 0.01 M HNO3 strip section for the removal of Sr from the SREX solvent, a 0.25 M Na2CO3 wash section to remove degradation products from the solvent, and a 0.1 M HNO3 rinse section. The behavior of 85Sr, Na, K, Al, B, Ca, Cr, Fe, Ni, and Zr was evaluated. The described flowsheet successfully extracted 85Sr from the dissolved pilot plant calcine with a removal efficiency of 99.6%. Distribution coefficients for 85Sr ranged from 3.6 to 4.5 in the extraction section. With these distribution coefficients a removal efficiency of approximately >99.99% was expected. It was determined that the lower than expected removal efficiency can be attributed to a stage efficiency of only 60% in the extraction section. Extracted K was effectively scrubbed from the SREX solvent with the 1.0 M NaNO3 resulting in only 6.4% of the K in the HLW strip product. Sodium was not extracted from the dissolved calcine by the SREX solvent; however, the use of a 1.0 M NaNO3 scrub solution resulted in a Na concentration of 70 mg/L (12.3% of the feed concentration) in the HLW strip product. Al, B, Ca, Cr, Fe, Ni, and Zr were determined to be essentially inextractable

  18. Anonymous aggregator election and data aggregation in wireless sensor networks

    OpenAIRE

    Tamás Holczer; Levente Buttyán

    2011-01-01

    In mission critical cyber-physical systems, dependability is an important requirement at all layers of the system architecture. In this paper, we propose protocols that increase the dependability of wireless sensor networks, which are potentially useful building blocks in cyber-physical systems. More specifically, we propose two private aggregator node election protocols, a private data aggregation protocol, and a corresponding private query protocol for sensor networks that allow for secure ...

  19. Arrow’s theorem in judgment aggregation

    OpenAIRE

    Dietrich, Franz; List, Christian

    2005-01-01

    In response to recent work on the aggregation of individual judgments on logically connected propositions into collective judgments, it is often asked whether judgment aggregation is a special case of Arrowian preference aggregation. We argue for the converse claim. After proving two impossibility theorems on judgment aggregation (using “systematicity” and “independence” conditions, respectively), we construct an embedding of preference aggregation into judgment aggregation and prove Arrow’s ...

  20. Idaho National Engineering and Environmental Laboratory, Old Waste Calcining Facility, Scoville vicinity, Butte County, Idaho -- Photographs, written historical and descriptive data. Historical American engineering record

    International Nuclear Information System (INIS)

    This report describes the history of the Old Waste Calcining Facility. It begins with introductory material on the Idaho National Engineering and Environmental Laboratory, the Materials Testing Reactor fuel cycle, and the Idaho Chemical Processing Plant. The report then describes management of the wastes from the processing plant in the following chapters: Converting liquid to solid wastes; Fluidized bed waste calcining process and the Waste Calcining Facility; Waste calcining campaigns; WCF gets a new source of heat; New Waste Calcining Facility; Last campaign; Deactivation and the RCRA cap; Significance/context of the old WCF. Appendices contain a photo key map for HAER photos, a vicinity map and neighborhood of the WCF, detailed description of the calcining process, and chronology of WCF campaigns

  1. Optimization of hydrogen dynamic heat treatment and re-calcination for preparation of strontium hexaferrite nanocrystalline powder

    International Nuclear Information System (INIS)

    Strontium hexaferrite is a hard magnetic material which under hydrogen treatment and re-calcination, its phase composition and also particles size and morphology change completely. Strontium hexaferrite was prepared by conventional route with calcination of strontium carbonate and hematite at 1100 deg. C for 1 h. Then strontium hexaferrite was heat treated in hydrogen dynamic atmosphere at various temperatures and gas flows for different times. Optimum conditions of hydrogen treatment were obtained at 850 deg. C with 60 cm3/min flow for 1 h. Subsequent re-calcination was carried out at various temperatures for the optimum hydrogen treated powder and its optimum conditions were obtained at 1000 deg. C for 1 h. The effect of dynamic hydrogen treatment and re-calcination on the phase composition and particles size and morphology characterized by X-ray diffraction (XRD) and scanning and transmission electron microscopes (SEM and TEM). The results showed decomposition of strontium hexaferrite and reduction of the resultant hematite mainly to iron during hydrogen treatment. Nanocrystalline powder of strontium hexaferrite was also reformed after the re-calcination. The magnetic properties of the initial and final strontium hexaferrite powder were measured by a vibration sample magnetometer (VSM). The results showed about 30% increase in the coercivity by application of this process on the strontium hexaferrite powder.

  2. CO{sub 2} capture capacity of CaO in long series of carbonation/calcination cycles

    Energy Technology Data Exchange (ETDEWEB)

    Grasa, G.S.; Abanades, J.C. [CSIC, Zaragoza (Spain)

    2006-12-20

    Calcium oxide can be an effective sorbent to separate CO{sub 2} at high temperatures. When coupled with a calcination step to produce pure CO{sub 2}, the carbonation reaction is the basis for several high-temperature CO{sub 2} capture systems. The evolution with cycling of the capture capacity of CaO derived from natural limestones is experimentally investigated in this work. Long series of carbonation/calcination cycles (up to 500) varying different variables affecting sorbent capacity have been tested in a thermogravimetric apparatus. Calcination temperatures above T > 950{sup o}C and very long calcination times accelerate the decay in sorption capacity, while other variables have a comparatively modest effect on the overall sorbent performance. A residual conversion of about 7-8% that remains constant after many hundreds of cycles and that seems insensitive to process conditions has been found. This residual conversion makes very attractive the carbonation/calcination cycle, by reducing (or even eliminating) sorbent purge rates in the system. A semiempirical equation has been proposed to describe sorbent conversion with the number of cycles based on these new long data series.

  3. Evaluation and Testing of IONSIV IE-911 for the Removal of Cesium-137 from INEEL Tank Waste and Dissolved Calcines

    International Nuclear Information System (INIS)

    Development of waste treatment processes for the remediation of radioactive wastes is currently underway. A number of experiments were performed at the Idaho Nuclear Technology and Environmental Center (INTEC) located at the Idaho National Engineering and Environmental Laboratory (INEEL) with the commercially available sorbent material, IONSIV IE-911, crystalline silicotitanate (CST), manufactured by UOP LLC. The purpose of this work was to evaluate the removal efficiency, sorbent capacity and selectivity of CST for removing Cs-137 from actual and simulated acidic tank waste in addition to dissolved pilot-plant calcine solutions. The scope of this work included batch contact tests performed with non-radioactive dissolved Al and Run-64 pilot plant calcines in addition to simulants representing the average composition of tank waste. Small-scale column tests were performed with actual INEEL tank WM-183 waste, tank waste simulant, dissolved Al and Run-64 pilot plant calcine solutions. Small-scale column experiments using actual WM-183 tank waste resulted in fifty-percent Cs-137 breakthrough at approximately 589 bed volumes. Small-scale column experiments using the tank waste simulant displayed fifty-percent Cs-137 breakthrough at approximately 700 bed volumes. Small-scale column experiments using dissolved Al calcine simulant displayed fifty-percent Cs-137 breakthrough at approximately 795 bed volumes. Column experiments with dissolved Run-64, pilot plant calcine did not reach fifty-percent breakthrough throughout the test

  4. The effects of calcination temperature on the electrochemical performance of LiMnPO4 prepared by ultrasonic spray pyrolysis

    International Nuclear Information System (INIS)

    Research highlights: → Carbon-coated LiMnPO4 cathode materials were prepared by ultrasonic spray pyrolysis. → The effects of calcinations temperature on the microstructure and electrochemical performance of C-LiMnPO4 were investigated. → X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) observations revealed that the calcination temperature had a strong influence on the morphology and crystallite size of the prepared final powder, and therefore the subsequent electrochemical performance of the material. → The C-LiMnPO4 powders prepared at 650 oC exhibited excellent electrochemical performance with a discharge capacity of 118 mAh g-1. - Abstract: Carbon-coated LiMnPO4 powders were prepared by ultrasonic spray pyrolysis. The effects of calcination temperature on the microstructure and electrochemical performance of C-LiMnPO4 were investigated. X-ray diffraction (XRD) studies showed that the crystallite size varied with calcination temperature. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) observations revealed that the calcination temperature had a strong influence on the morphology of the prepared final powder, and therefore the subsequent electrochemical performance of the material. The C-LiMnPO4 powders prepared at 650 oC exhibited excellent electrochemical performance with a discharge capacity of 118 mAh g-1.

  5. Aggregated Computational Toxicology Resource (ACTOR)

    Data.gov (United States)

    U.S. Environmental Protection Agency — The Aggregated Computational Toxicology Resource (ACTOR) is a database on environmental chemicals that is searchable by chemical name and other identifiers, and by...

  6. Implementation of industrial waste ferrochrome slag in conventional and low cement castables: Effect of calcined alumina

    Directory of Open Access Journals (Sweden)

    Pattem Hemanth Kumar

    2014-12-01

    Full Text Available A new class of conventional and low-cement ferrochrome slag-based castables were prepared from 40 wt.% ferrochrome slag and 45 wt.% calcined bauxite. Rest fraction varied between high alumina cement (HAC acting as hydraulic binder and calcined alumina as pore filling additive. Standard ASTM size briquettes were prepared for crushing and bending strengths evaluation, and the samples were then subjected to firing at 800, 1100 and 1300 °C for a soaking period of 3 h. The microstructure and refractory properties of the prepared castables have been investigated using X-ray diffraction (XRD, scanning electron microscopy (SEM, cold crushing strength, modulus of rupture and permanent linear changes (PLCs test. Castables show good volume stability (linear change <0.7% at 1300 °C. The outcomes of these investigations were efficacious and in accordance with previously reported data of similar compositions. High thermo-mechanical and physico-chemical properties were attained pointing out an outstanding potential to increase the refractory lining working life of non-recovery coke oven and reheating furnaces.

  7. Pecularities of carrying out radioactive wastes vitrification process without preliminary calcination of wastes

    International Nuclear Information System (INIS)

    Vitrification technology is considered for liquid radioactive wastes by means of electric furnace where heating of glass-paste is done by electric current passing through the melt. Continious process of gehydration, calcination and vitrification is going on in one apparatus. Testing if the method has been performed by use of a model solution, containing sodium and aluminium nitrates. To obtain phosphoric acid has been added into the solution. Lay-out of the device and its description as well as technical parameters of the electric furnace are given. The results are stated for determination of the optimum operation conditions for the device. To reduce entrainment of solid components, molasses has been added in the solution. Parameters are given for the process of the solution containing 80 g/l molasses processing. It has been shown that edding molasses to the solution permitted to reduse power consumption of the process due to the heat generation during oxidation-reduction reaction on the melt surface. The results are given for investigations of the nitrogen oxides catching in scrubbers. These results have shown that introduction of molasses reduces nitrigen oxides concentration. The results of the experimental works have shown the possibility of the continious process of dehydration, calcination and vitrification in single device with application of remote control and monitoring by means of automatics. (I.T.)

  8. Calcined Mg-Fe layered double hydroxide as an absorber for the removal of methyl orange

    Energy Technology Data Exchange (ETDEWEB)

    Peng, Chao [School of Civil Engineering and Mechanics, Central South University of Forestry and Technology, Changsha 410004, Hunan (China); State Key Laboratory of Silicate Materials for Architectures, Wuhan University of Technology, Wuhan 430070 (China); Dai, Jing [Key Laboratory of Advanced Technology for Special Functional Materials of Ministry of Education, Wuhan 430070 (China); Yu, Jianying, E-mail: Yujianyingwhut@163.com [State Key Laboratory of Silicate Materials for Architectures, Wuhan University of Technology, Wuhan 430070 (China); Yin, Jian [School of Civil Engineering and Mechanics, Central South University of Forestry and Technology, Changsha 410004, Hunan (China)

    2015-05-15

    In this work, methyl orange (MO) was effectively removed from aqueous solution with the calcined product of hydrothermal synthesized Mg/Fe layered double hydroxide (Mg/Fe-LDH). The structure, composition, morphology and textural properties of the Mg/Fe-LDH before and after adsorption were characterized by X-ray diffraction, Fourier transformation infrared spectroscopy, transmission electron microscopy, nitrogen adsorption apparatus and X-ray photoelectron spectroscopy. It was confirmed that MO had been absorbed by calcined Mg/Fe-LDH which had strong interactions with MO. The adsorption of MO onto the Mg/Fe-LDH was systematically investigated by batch tests. The adsorption capacity of the Mg/Fe-LDH toward MO was found to be 194.9 mg • g{sup −1}. Adsorption kinetics and isotherm studies revealed that the adsorption of MO onto Mg/Fe-LDH was a spontaneous and endothermic process. These results indicate that Mg/Fe-LDH is a promising material for the removal of MO.

  9. Mercury removal at Idaho National Engineering and Environmental Laboratory's New Waste Calciner Facility

    International Nuclear Information System (INIS)

    Technologies were investigated to determine viable processes for removing mercury from the calciner (NWCF) offgas system at the Idaho National Engineering and Environmental Laboratory. Technologies for gas phase and aqueous phase treatment were evaluated. The technologies determined are intended to meet EPA Maximum Achievable Control Technology (MACT) requirements under the Clean Air Act and Resource Conservation and Recovery Act (RCRA). Currently, mercury accumulation in the calciner off-gas scrubbing system is transferred to the tank farm. These transfers lead to accumulation in the liquid heels of the tanks. The principal objective for aqueous phase mercury removal is heel mercury reduction. The system presents a challenge to traditional methods because of the presence of nitrogen oxides in the gas phase and high nitric acid in the aqueous scrubbing solution. Many old and new technologies were evaluated including sorbents and absorption in the gas phase and ion exchange, membranes/sorption, galvanic methods, and UV reduction in the aqueous phase. Process modifications and feed pre-treatment were also evaluated. Various properties of mercury and its compounds were summarized and speciation was predicted based on thermodynamics. Three systems (process modification, NOxidizer combustor, and electrochemical aqueous phase treatment) and additional technology testing were recommended

  10. Morphological characterization of silica obtained by calcination of methacrylic and epoxy - silica hybrid systems

    Science.gov (United States)

    Tescione, F.; Lionetto, F.; Corcione, C. Esposito; Buonocore, G. G.; Striani, R.; Lavorgna, M.; Frigione, M.

    2016-05-01

    The work is addressed to investigating the potentiality of calcination of organic-inorganic (O-I) hybrids as a feasible approach to produce silica particles, at mild temperature conditions and with tailored morphology. Two different innovative hybrid systems were obtained through sol-gel process with a siloxane content ranging from 6 to 26wt%. The two O-I hybrids differed for i) the organic matrix (methacrylic or epoxy), ii) its crosslinking mechanism (photopolymerization for methacrylic systems or thermal cold-cure for epoxy systems) and iii) the rate ratio between sol-gel and crosslinking reactions. Different characterization techniques were used to understand the effect of composition and curing method on the morphology of the silica obtained from O-I hybrids after calcination in air. The results confirm the morphology and properties of silica particles in terms of surface and porosity may be tailored over a wide range by varying the composition and nature of organic and inorganic precursors of hybrids.

  11. Comparison of CaO-based synthetic CO{sub 2} sorbents under realistic calcination conditions

    Energy Technology Data Exchange (ETDEWEB)

    Gemma Grasa; Belen Gonzalez; Monica Alonso; J. Carlos Abanades [Instituto de Carboquimica (CSIC), Zaragoza (Spain)

    2007-12-15

    Several concepts to capture CO{sub 2} in power plants and hydrogen generation plants are under development using CaO as regenerable sorbent. The drastic decay in sorbent capture capacity of CaO obtained through calcination of natural sources of CaCO{sub 3} (limestones or dolomites) justifies the search of synthetic sorbents that aim to overcome this decay in capture capacity. We have reviewed some of the recent literature on the subject and tested some of the proposed sorbents under comparable conditions. Our results confirm the good performance of some of these synthetic sorbents under mild conditions and/or long carbonation times used in the original references. However, we show that these sorbents deactivate also very quickly when realistic regeneration conditions (high temperatures for calcination at high partial pressures of CO{sub 2}) are used in the laboratory test. We conclude that none of the reviewed sorbents have a chance to compete with the performance of natural limestones, of much lower cost. 24 refs., 4 figs.

  12. Calcination temperature influenced multiferroic properties of Ca-doped BiFeO3 nanoparticles

    International Nuclear Information System (INIS)

    The influence of Ca-doping and particle size on structural, morphological and magnetic properties of BiFeO3 nanoparticles has been studied. A sol-gel method was employed for the synthesis of nanoparticles and their particle size was tailored by varying the calcination temperature. Structural analysis revealed a rhombohedral distortion induced by Ca-substitution. The broadening of diffraction peaks with decreasing calcination temperature was indicative of reduction in crystallite size. The morphological analysis revealed the formation of agglomerated nanoparticles having average particle size ranging from 10-15 and 50-55 nm for C4 and C6, respectively. The agglomeration is attributed to high surface energy of nanoparticles. Ferromagnetism has been displayed by all the synthesized nanoparticles. Enhancement of saturation magnetization with Ca-substitution is attributed to suppression of spin cycloid structure by the reduction in size, lattice distortion and creation of oxygen vacancies by the substitution of divalent ion at trivalent site. Further, this value increases as a function of decreasing particle size. Strong particle size effects on magnetic properties of the synthesized nanoparticles are owed to increasing surface to volume ratio. All these observations are indicative of strong dependence of multiferroism on particle size

  13. Removal of acid blue 062 on aqueous solution using calcinated colemanite ore waste

    International Nuclear Information System (INIS)

    Colemanite ore waste (CW) has been employed as adsorbent for the removal of acid blue 062 anionic dye (AB 062) from aqueous solution. The adsorption of AB 062 onto CW was examined with respect to contact time, calcination temperature, particle size, pH, adsorbent dosage and temperature. The physical and chemical properties of the CW, such as particle sizes and calcinations temperature, play important roles in dye adsorption. The dye adsorption largely depends on the initial pH of the solution with maximum uptake occurring at pH 1.Three simplified kinetics models, namely, pseudo-first order, pseudo-second order, and intraparticle diffusion models were tested to investigate the adsorption mechanisms. The kinetic adsorption of AB 062 on CW follows a pseudo-second order equation. The adsorption data have been analyzed using Langmuir and Freundlich isotherms. The results indicate that the Langmuir model provides the best correlation of the experimental data. Isotherms have also been used to obtain the thermodynamic parameters such as free energy, enthalpy and entropy of the adsorption of dye onto CW

  14. Manganese oxide phases and morphologies: A study on calcination temperature and atmospheric dependence

    Directory of Open Access Journals (Sweden)

    Matthias Augustin

    2015-01-01

    Full Text Available Manganese oxides are one of the most important groups of materials in energy storage science. In order to fully leverage their application potential, precise control of their properties such as particle size, surface area and Mnx+ oxidation state is required. Here, Mn3O4 and Mn5O8 nanoparticles as well as mesoporous α-Mn2O3 particles were synthesized by calcination of Mn(II glycolate nanoparticles obtained through an economical route based on a polyol synthesis. The preparation of the different manganese oxides via one route facilitates assigning actual structure–property relationships. The oxidation process related to the different MnOx species was observed by in situ X-ray diffraction (XRD measurements showing time- and temperature-dependent phase transformations occurring during oxidation of the Mn(II glycolate precursor to α-Mn2O3 via Mn3O4 and Mn5O8 in O2 atmosphere. Detailed structural and morphological investigations using transmission electron microscopy (TEM and powder XRD revealed the dependence of the lattice constants and particle sizes of the MnOx species on the calcination temperature and the presence of an oxidizing or neutral atmosphere. Furthermore, to demonstrate the application potential of the synthesized MnOx species, we studied their catalytic activity for the oxygen reduction reaction in aprotic media. Linear sweep voltammetry revealed the best performance for the mesoporous α-Mn2O3 species.

  15. Calcined Mg-Fe layered double hydroxide as an absorber for the removal of methyl orange

    International Nuclear Information System (INIS)

    In this work, methyl orange (MO) was effectively removed from aqueous solution with the calcined product of hydrothermal synthesized Mg/Fe layered double hydroxide (Mg/Fe-LDH). The structure, composition, morphology and textural properties of the Mg/Fe-LDH before and after adsorption were characterized by X-ray diffraction, Fourier transformation infrared spectroscopy, transmission electron microscopy, nitrogen adsorption apparatus and X-ray photoelectron spectroscopy. It was confirmed that MO had been absorbed by calcined Mg/Fe-LDH which had strong interactions with MO. The adsorption of MO onto the Mg/Fe-LDH was systematically investigated by batch tests. The adsorption capacity of the Mg/Fe-LDH toward MO was found to be 194.9 mg • g−1. Adsorption kinetics and isotherm studies revealed that the adsorption of MO onto Mg/Fe-LDH was a spontaneous and endothermic process. These results indicate that Mg/Fe-LDH is a promising material for the removal of MO

  16. Isolation and Aggregation in Economics

    OpenAIRE

    Schlicht, Ekkehart

    1985-01-01

    In explaining economic phenomena, economic analysis concentrates on selected influences and fixes the host of other factors under a ceteris paribus clause. This view, which goes back to Alfred Marshall (1842-1924), is developed in the first part of the book. Aggregation is viewed as a particular application of ceteris paribus analysis - isolation from "structural effects". This leads to an approach, called "closed aggregation", which was introduced by Kenneth May and is also implicit in Keyne...

  17. Judgment aggregation with consistency alone

    OpenAIRE

    Dietrich, Franz; List, Christian

    2007-01-01

    All existing impossibility theorems on judgment aggregation require individ- ual and collective judgment sets to be consistent and complete (in some recent results with completeness relaxed to deductive closure), arguably a demand- ing rationality requirement. They do not carry over to aggregation functions mapping pro…les of (merely) consistent individual judgment sets to (merely) consistent collective ones. We prove that, whenever the agenda of propositions under consideration exhibits mild...

  18. Judgment aggregation without full rationality

    OpenAIRE

    Dietrich, Franz; List, Christian

    2007-01-01

    Several recent results on the aggregation of judgments over logically connected propositions show that, under certain conditions, dictatorships are the only independent (i.e., propositionwise) aggregation rules generating fully rational (i.e., complete and consistent) collective judgments. A frequently mentioned route to avoid dictatorships is to allow incomplete collective judgments. We show that this route does not lead very far: we obtain (strong) oligarchies rather than dictatorships if i...

  19. Familial aggregation of cluster headache

    OpenAIRE

    Cruz, S; Lemos, C; Monteiro, JM

    2013-01-01

    Several studies suggest a strong familial aggregation for cluster headache (CH), but so far none of them have included subjects with probable cluster headache (PCH) in accordance with the International Classification of Headache Disorders. OBJECTIVE: To identify cases of probable cluster headache and to assess the familial aggregation of cluster headache by including these subjects. METHOD: Thirty-six patients attending a headache consultation and diagnosed with trigeminal autonom...

  20. Familial aggregation of cluster headache

    OpenAIRE

    Simao Cruz; Carolina Lemos; Jose Maria Pereira Monteiro

    2013-01-01

    Several studies suggest a strong familial aggregation for cluster headache (CH), but so far none of them have included subjects with probable cluster headache (PCH) in accordance with the International Classification of Headache Disorders. Objective To identify cases of probable cluster headache and to assess the familial aggregation of cluster headache by including these subjects. Method Thirty-six patients attending a headache consultation and diagnosed with trigeminal autonomic headache...

  1. Glycation precedes lens crystallin aggregation

    International Nuclear Information System (INIS)

    Non-enzymatic glycosylation (glycation) seems to have the potential to alter the structure of crystallins and make them susceptible to thiol oxidation leading to disulfide-linked high molecular weight (HMW) aggregate formation. They used streptozotocin diabetic rats during precataract and cataract stages and long-term cell-free glycation of bovine lens crystallins to study the relationship between glycation and lens crystallin aggregation. HMW aggregates and other protein components of the water-soluble (WS) and urea-soluble (US) fractions were separated by molecular sieve high performance liquid chromatography. Glycation was estimated by both [3H]NaBH4 reduction and phenylboronate agarose affinity chromatography. Levels of total glycated protein (GP) in the US fractions were about 2-fold higher than in the WS fractions and there was a linear increase in GP in both WS and US fractions. This increase was parallelled by a corresponding increase in HMW aggregates. Total GP extracted by the affinity method from the US fraction showed a predominance of HMW aggregates and vice versa. Cell-free glycation studies with bovine crystallins confirmed the results of the animals studies. Increasing glycation caused a corresponding increase in protein insolubilization and the insoluble fraction thus formed also contained more glycated protein. It appears that lens protein glycation, HMW aggregate formation, and protein insolubilization are interrelated

  2. Kinetic model for erythrocyte aggregation.

    Science.gov (United States)

    Bertoluzzo, S M; Bollini, A; Rasia, M; Raynal, A

    1999-01-01

    It is well known that light transmission through blood is the most widely utilized method for the study of erythrocyte aggregation. The curves obtained had been considered empirically as exponential functions. In consequence, the process becomes characterized by an only parameter that varies with all the process factors without discrimination. In the present paper a mathematical model for RBC aggregation process is deduced in accordance with von Smoluchowski's theory about the kinetics of colloidal particles agglomeration. The equation fitted the experimental pattern of the RBC suspension optical transmittance closely and contained two parameters that estimate the most important characteristics of the aggregation process separately, i.e., (1) average size of rouleaux at equilibrium and (2) aggregation rate. The evaluation of the method was assessed by some factors affecting erythrocyte aggregation, such as temperature, plasma dilutions, Dextran 500, Dextran 70 and PVP 360, at different media concentrations, cellular membrane alteration by the alkylating agent TCEA, and decrease of medium osmolarity. Results were interpreted considering the process characteristics estimated by the parameters, and there were also compared with similar studies carried out by other authors with other methods. This analysis allowed us to conclude that the equation proposed is reliable and useful to study erythrocyte aggregation. PMID:10660481

  3. Effects of Calcination Condition on Photocatalytic Properties of Nano-TiO2/Opal Composite and Its Mechanism

    Directory of Open Access Journals (Sweden)

    WANG Bin, ZHENG Shui-Lin, WEN Ming, ZHANG Guang-Xin

    2014-08-01

    Full Text Available Nanocrystalline TiO2 particles immobilized on opal by a hydrolysis precipitation method are used as a novel catalyst in photocatalysis. Effects of crystalline and size, BET specific surface area and porous properties on the photoactivity were investigated by characterizing samples obtained under various calcination temperatures and periods. Results reveal that there is still no evidence of rutile phase in XRD patterns when the calcination temperature increases to 800°C. This indicates that the opal support impedes the phase transformation. The photocatalytic reactivity of this nano-TiO2/opal composite catalyst was evaluated by degrading Rhodamine B (RhB under ultraviolet light. The sample calcined at 600°C for 2 h exhibits the smaller crystalline size and larger specific surface area with a concomitant higher activity of 97.24% for RhB degradation by 4 h irradiation under 250 W Hg lamp.

  4. QUERY PLANNING FOR CONTINUOUS AGGREGATION QUERIES USING DATA AGGREGATORS

    Directory of Open Access Journals (Sweden)

    A. SATEESH, D. ANIL, M. KIRANKUMAR

    2013-08-01

    Full Text Available Continuous aggregation queries are used to monitor the changes in data with time varying for online decision making. For continuous queries low cost and scalable techniques used a network of aggregators. Individual node cannot by itself determine its inclusion in the query result for this a different algorithmic challenges from aggregate and selection queries are presented. At specific coherencies each data item can serve for a set of data aggregators. Technique involves disseminating query into sub query and sub queries are executed on the chosen data aggregators. We build a query cost model which can be used to estimate the number of refresh messages which is required to satisfy the client specified incoherency bound. Performance results shows that by our method the query can be executed using less than one third the messages required for existing schemes. Our adaptive strategy employs distributed decisions made by the distributed servers independently based on localized statistics collected by each server at runtime. When comparatively static environment, propose two motionless tree construction algorithms relying on apriori system statistics. These static trees can also be used as early trees in a dynamic environment and apply our schemes to both single- and multi object distribution. Our extensive performance study illustrate that the adaptive mechanisms.

  5. Preparation and thermal energy storage properties of paraffin/calcined diatomite composites as form-stable phase change materials

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Zhiming [School of Chemical and Environmental Engineering, China University of Mining and Technology, Beijing 100083 (China); Chemistry Discipline, Faculty of Science and Technology, Queensland University of Technology, 2 George Street, GPO Box 2434, Brisbane, Queensland 4001 (Australia); Zhang, Yuzhong [School of Chemical and Environmental Engineering, China University of Mining and Technology, Beijing 100083 (China); Zheng, Shuilin, E-mail: shuilinzh@yahoo.com.cn [School of Chemical and Environmental Engineering, China University of Mining and Technology, Beijing 100083 (China); Park, Yuri [Chemistry Discipline, Faculty of Science and Technology, Queensland University of Technology, 2 George Street, GPO Box 2434, Brisbane, Queensland 4001 (Australia); Frost, Ray L., E-mail: r.frost@qut.edu.au [Chemistry Discipline, Faculty of Science and Technology, Queensland University of Technology, 2 George Street, GPO Box 2434, Brisbane, Queensland 4001 (Australia)

    2013-04-20

    Highlights: ► Composite phase change material (PCM) was prepared by blending composite paraffin and calcined diatomite. ► The optimum mixed proportion was obtained through differential scanning calorimetry. ► Thermal energy storage properties of the composite PCMs were determined by DSC. ► Thermal cycling test showed that the prepared PCMs are thermally reliable and chemically stable. - Abstract: A composite paraffin-based phase change material (PCM) was prepared by blending composite paraffin and calcined diatomite through the fusion adsorption method. In this study, raw diatomite was purified by thermal treatment in order to improve the adsorption capacity of diatomite, which acted as a carrier material to prepare shape-stabilized PCMs. Two forms of paraffin (paraffin waxes and liquid paraffin) with different melting points were blended together by the fusion method, and the optimum mixed proportion with a suitable phase-transition temperature was obtained through differential scanning calorimetry (DSC) analysis. Then the prepared composite paraffin was adsorbed in calcined diatomite. The prepared paraffin/calcined diatomite composites were characterized by the scanning electron microscope (SEM) and Fourier transformation infrared (FT-IR) analysis techniques. Thermal energy storage properties of the composite PCMs were determined by DSC method. DSC results showed that there was an optimum adsorption ratio between composite paraffin and calcined diatomite and the phase-transition temperature and the latent heat of the composite PCMs were 33.04 °C and 89.54 J/g, respectively. Thermal cycling test of composite PCMs showed that the prepared material is thermally reliable and chemically stable. The obtained paraffin/calcined diatomite composites have proper latent heat and melting temperatures, and show practical significance and good potential application value.

  6. Fractal Aggregates in Tennis Ball Systems

    Science.gov (United States)

    Sabin, J.; Bandin, M.; Prieto, G.; Sarmiento, F.

    2009-01-01

    We present a new practical exercise to explain the mechanisms of aggregation of some colloids which are otherwise not easy to understand. We have used tennis balls to simulate, in a visual way, the aggregation of colloids under reaction-limited colloid aggregation (RLCA) and diffusion-limited colloid aggregation (DLCA) regimes. We have used the…

  7. Growth reactions of potassium titanate fibers by slow-cooling calcination method

    International Nuclear Information System (INIS)

    The growth of potassium titanate fibers was studied by a new growth technique called ''slow-cooling calcination method''. By this method, a specific composition is incongruently melted into a solid phase and liquid phase, and then is slowly cooled to a temperature region below the incongruent-melting temperature. Fibrous crystals are grown by a incongruent melt-association reaction between the solid and liquid phases during the cooling precess. In the system K2Ti2O5-K2Ti6O13, a stating material having the n value between 2 2O.nTiO2 formula was incongruently melted into a liquid phase and K2Ti6O13 solid phase at above the incongruent-melting temperature (11140CFF+-FF150C) of K2Ti4O9, and then was slowly cooled to a temperature region below 11140C. During the slow-cooling process, the incongruently melted K2Ti6O13 solid phase and liquid phase again reacted to associate. This association reaction plays a very important role to grow potassium titanate fibers, especially K2Ti4O9 fibers. Relatively long fibers were grown in the mixed fibers of K2Ti4O9 and K2Ti2O5 when a starting material of K2O.2.8 TiO2 composition was calcined at 11500C for 4 h, and then was slowly cooled to 9500C with a rate of 160C/h, and was followed by quenching to room temperature. Consequently, the K2Ti4O9 fibers in them were grown by an incongruent melt-association reaction, and the K2Ti2O5 fibers were crystallized from the liquid phase during the quenching process. The growth of K2Ti4O9 fibers was mainly depended upon three factors of starting composition, calcination temperature and cooling rate, and furthermore was also promoted by repeating the incongruent melt-association reaction. (author)

  8. An exact approach for aggregated formulations

    DEFF Research Database (Denmark)

    Gamst, Mette; Spoorendonk, Simon; Røpke, Stefan

    Aggregating formulations is a powerful approach for problems to take on tractable forms. Aggregation may lead to loss of information, i.e. the aggregated formulation may be an approximation of the original problem. In branch-and-bound context, aggregation can also complicate branching, e.g. when...... optimality cannot be guaranteed by branching on aggregated variables. We present a generic exact solution method to remedy the drawbacks of aggregation. It combines the original and aggregated formulations and applies Benders' decomposition. We apply the method to the Split Delivery Vehicle Routing Problem....

  9. Destructive Strength Properties of Recycled Coarse Aggregate

    OpenAIRE

    Chetna M Vyas,; Darshana R Bhatt,

    2013-01-01

    Due to a critical shortage of natural aggregate, the availability of demolished concrete for use as recycled coarse aggregate (RCA) is increasing. Use of waste concrete as RCA conserves natural aggregate, reduces the impact on landfills, save energy and can provide cost benefit. Recycled aggregates are the materials for the future. The application of recycled aggregate has been started in many Asian & Western countries for construction projects. Research Paper reports the basic strength prope...

  10. Erythrocyte aggregation: Basic aspects and clinical importance

    OpenAIRE

    Başkurt, Oğuz K.; Meiselman, Herbert J.

    2013-01-01

    Red blood cells (RBC) aggregate to form two- and three-dimensional structures when suspended in aqueous solutions containing large plasma proteins or polymers; this aggregation is reversible and shear dependent (i.e., dispersed at high shear and reformed at low or stasis). The extent of aggregation is the main determinant of low shear blood viscosity, thus predicting an inverse relationship between aggregation and in vivo blood flow. However, the effects of aggregation on hemodynamic mechanis...

  11. Individual income, incomplete information, and aggregate consumption

    OpenAIRE

    Pischke, J.

    1991-01-01

    In this paper I study a model of life-cycle consumption in which individuals react optimally to their own income process but ignore economy wide information. Since individual income is less persistent than aggregate income consumers will react too little to aggregate income variation. Aggregate consumption will be excessively smooth. Since aggregate information is slowly incorporated into consumption, aggregate consumption will be autocorrelated and correlated with lagged income. The second p...

  12. Study of Surface Modification Mechanism of Calcined Kaolin by MAS NMR

    Institute of Scientific and Technical Information of China (English)

    杨晓杰; 邓飞皇; 张蓓

    2002-01-01

    The 29Si and 27Al in modified and unmodified calcined kaolin were res earched and compared by using MAS NMR. The result shows that the chemical shift of -106×10-6 of 29Si almost keeps unchanged after being modifie d, but 27Al cha nges obviously. The chemical shift of 5.44×10-6 and 65.69×10-6 of 27Al are sep arately shifted to 3.8×10-6-4.4×10-6 and 54.6×10-6-59.9×1 0-6 after being mod ified. And the chemical modification of kaolin is completed by linking with Al o n the surface of it.

  13. Application of coal-water slurry on the rotary calcining kiln of pedgion magnesium reduction process

    Institute of Scientific and Technical Information of China (English)

    LI Hua-qing; XIE Shui-sheng; LIU Jin-ping; WU Peng-yue; HUANG Guo-jie

    2006-01-01

    Energy saving has been an important concept in modern industry especially to the countries and regions with energy shortage such as China and Japan. Utilization of Coal-Water Slurry (CWS) can improve the burning efficiency of coal and reduce the pollutions of soot, sulfide and the nitride by burning lump coal directly. The CWS is a promising energy saving technique and the effectual substitute of oil. The study on the preparation and application of the CWS has made progresses in many aspects. The present paper studied the basal problems for applying the CWS on the rotary kilns during the calcining-dolomite process in the magnesium factory, summarized the key points for the application process of the CWS and gave the corresponding solutions.

  14. Enhancement of biohydrogen production from brewers' spent grain by calcined-red mud pretreatment.

    Science.gov (United States)

    Zhang, Jishi; Zang, Lihua

    2016-06-01

    This paper investigated the utilization of calcined-red mud (CRM) pretreatment to enhance fermentative hydrogen yields from brewers' spent grain (BSG). The BSG samples were treated with different concentrations (0.0-20g/L) of CRM at 55°C for 48h, before the biohydrogen process with heat-treated anaerobic sludge inoculum. The highest specific hydrogen production of 198.62ml/g-VS was obtained from the BSG treated with 10g/L CRM, with the corresponding lag time of 10.60h. Hydrogen yield increments increased by 67.74%, compared to the control tests without CRM. The results demonstrated that the CRM could hydrolyze more cellulose and further provided adequate broth and suitable pH value for efficient fermentative hydrogen. The model-based analysis showed that the modified Gompertz model presented a better fit for the experimental data than the first-order model. PMID:26950758

  15. Effect of calcination temperature on phase transformation of HfO2 nanoparticles

    International Nuclear Information System (INIS)

    Oxides nanomaterials exhibit unique physical, chemical and structural properties and motivated a big research that focus in the integration of these materials for various optoelectronic device applications. In present work, hafnium oxide (HfO2) nanoparticles (NPs) have been synthesized using precipitation method. Hafnium tetrachloride and sodium hydroxide has been used as starting precursors. Prepared oxide material has been characterized by X-Ray Diffraction (XRD), Fourier Transform Infra-Red (FTIR) and UV-Vis spectroscopy. The phase transformation from amorphous to monoclinic is observed with the increase in calcination temperature from 500 °C and 800 °C. In FTIR spectra, the characteristic bands at ν ∼ 758.53 and 509.57 cm−1 reveals the monoclinic phase of prepared HfO2 NPs. UV-Vis spectroscopy shows an absorption peak at 204 nm and the bandgap calculated is 6.07 eV

  16. Turbulent breakage of ductile aggregates

    CERN Document Server

    Marchioli, Cristian

    2015-01-01

    In this paper we study breakage rate statistics of small colloidal aggregates in non-homogeneous anisotropic turbulence. We use pseudo-spectral direct numerical simulation of turbulent channel flow and Lagrangian tracking to follow the motion of the aggregates, modelled as sub-Kolmogorov massless particles. We focus specifically on the effects produced by ductile rupture: This rupture is initially activated when fluctuating hydrodynamic stresses exceed a critical value, $\\sigma>\\sigma_{cr}$, and is brought to completion when the energy absorbed by the aggregate meets the critical breakage value. We show that ductile rupture breakage rates are significantly reduced with respect to the case of instantaneous brittle rupture (i.e. breakage occurs as soon as $\\sigma>\\sigma_{cr}$). These discrepancies are due to the different energy values at play as well as to the statistical features of energy distribution in the anisotropic turbulence case examined.

  17. Equilibrium structure of ferrofluid aggregates

    International Nuclear Information System (INIS)

    We study the equilibrium structure of large but finite aggregates of magnetic dipoles, representing a colloidal suspension of magnetite particles in a ferrofluid. With increasing system size, the structural motif evolves from chains and rings to multi-chain and multi-ring assemblies. Very large systems form single- and multi-wall coils, tubes and scrolls. These structural changes result from a competition between various energy terms, which can be approximated analytically within a continuum model. We also study the effect of external parameters such as magnetic field on the relative stability of these structures. Our results may give insight into experimental data obtained during solidification of ferrofluid aggregates at temperatures where thermal fluctuations become negligible in comparison to inter-particle interactions. These data may also help to experimentally control the aggregation of magnetic particles.

  18. Molecular Aggregation in Disodium Cromoglycate

    Science.gov (United States)

    Singh, Gautam; Agra-Kooijman, D.; Collings, P. J.; Kumar, Satyendra

    2012-02-01

    Details of molecular aggregation in the mesophases of the anti-asthmatic drug disodium cromoglycate (DSCG) have been studied using x-ray synchrotron scattering. The results show two reflections, one at wide angles corresponding to π-π stacking (3.32 å) of molecules, and the other at small angles which is perpendicular to the direction of molecular stacking and corresponds to the distance between the molecular aggregates. The latter varies from 35 - 41 å in the nematic (N) phase and 27 -- 32 å in the columnar (M) phase. The temperature evolution of the stack height, positional order correlations in the lateral direction, and orientation order parameter were determined in the N, M, and biphasic regions. The structure of the N and M phases and the nature of the molecular aggregation, together with their dependence on temperature and concentration, will be presented.

  19. Photostimulated Aggregation of Metal Aerosols

    CERN Document Server

    Karpov, Sergei V

    2010-01-01

    The effect of optical radiation on the rate of aggregation of nanoscopic particles is studied in metal aerosols. It has been shown that under light exposure, polydisperse metal aerosols can aggregate up to two orders faster due to the size dependent photoelectron effect from nanoparticles. Different size nanoparticles undergo mutual heteropolar charging when exchanging photoelectrons through the interparticle medium to result in an increased rate of aggregation. It is shown that long-range electrostatic attractive forces drive the particles into closer distances where the short-range Van-der-Waals forces become dominating. Attention is drawn to the fact that this effect may occur in various types of dispersed systems as well as in natural heteroaerosols.

  20. Quantum Diffusion-Limited Aggregation

    CERN Document Server

    Johnson, David B

    2011-01-01

    Though classical random walks have been studied for many years, research concerning their quantum analogues, quantum random walks, has only come about recently. Numerous simulations of both types of walks have been run and analyzed, and are generally well-understood. Research pertaining to one of the more important properties of classical random walks, namely, their ability to build fractal structures in diffusion-limited aggregation, has been particularly noteworthy. However, only now has research begun in this area in regards to quantum random motion. The study of random walks and the structures they build has various applications in materials science. Since all processes are quantum in nature, it is important to consider the quantum variant of diffusion-limited aggregation. Recognizing that Schr\\"odinger equation and a classical random walk are both diffusion equations, it is possible to connect and compare them. Using similar parameters for both equations, we ran various simulations aggregating particles....

  1. Balancing energy flexibilities through aggregation

    DEFF Research Database (Denmark)

    Valsomatzis, Emmanouil; Hose, Katja; Pedersen, Torben Bach

    2014-01-01

    in both energy production and consumption, is the key to solving these problems. Flexibilities can be expressed as flex-offers, which due to their high number need to be aggregated to reduce the complexity of energy scheduling. In this paper, we discuss balance aggregation techniques that already......One of the main goals of recent developments in the Smart Grid area is to increase the use of renewable energy sources. These sources are characterized by energy fluctuations that might lead to energy imbalances and congestions in the electricity grid. Exploiting inherent flexibilities, which exist...... during aggregation aim at balancing flexibilities in production and consumption to reduce the probability of congestions and reduce the complexity of scheduling. We present results of our extensive experiments....

  2. Surface complexation modeling calculation of Pb(II) adsorption onto the calcined diatomite

    Science.gov (United States)

    Ma, Shu-Cui; Zhang, Ji-Lin; Sun, De-Hui; Liu, Gui-Xia

    2015-12-01

    Removal of noxious heavy metal ions (e.g. Pb(II)) by surface adsorption of minerals (e.g. diatomite) is an important means in the environmental aqueous pollution control. Thus, it is very essential to understand the surface adsorptive behavior and mechanism. In this work, the Pb(II) apparent surface complexation reaction equilibrium constants on the calcined diatomite and distributions of Pb(II) surface species were investigated through modeling calculations of Pb(II) based on diffuse double layer model (DLM) with three amphoteric sites. Batch experiments were used to study the adsorption of Pb(II) onto the calcined diatomite as a function of pH (3.0-7.0) and different ionic strengths (0.05 and 0.1 mol L-1 NaCl) under ambient atmosphere. Adsorption of Pb(II) can be well described by Freundlich isotherm models. The apparent surface complexation equilibrium constants (log K) were obtained by fitting the batch experimental data using the PEST 13.0 together with PHREEQC 3.1.2 codes and there is good agreement between measured and predicted data. Distribution of Pb(II) surface species on the diatomite calculated by PHREEQC 3.1.2 program indicates that the impurity cations (e.g. Al3+, Fe3+, etc.) in the diatomite play a leading role in the Pb(II) adsorption and dominant formation of complexes and additional electrostatic interaction are the main adsorption mechanism of Pb(II) on the diatomite under weak acidic conditions.

  3. Proposed Atomic Energy of Canada Ltd. 99Mo waste calcination process

    International Nuclear Information System (INIS)

    Atomic Energy of Canada Limited (AECL), at its Chalk River Laboratory, generates from 3000 to 5000 L/year of high-level fissile waste solution from the production of 99Mo. In this Mo process, highly enriched uranium (93 wt % 235U, total uranium basis) contained in uranium-aluminum alloy target rods is irradiated to produce the 99Mo product. The targets are removed from the reactor and dissolved in a mercury nitrate-catalyzed reaction with nitric acid. The 99Mo product is then recovered by passing the solution through an alumina (Al2O3) column. During discussions with personnel from the Oak Ridge National Laboratory (ORNL) on September 10, 1992, the ORNL-developed technology formerly applied to the solidification of aqueous uranium waste (Consolidated Edison Uranium Solidification Program or CEUSP) was judged potentially applicable to the AECL 99Mo waste. Under a Work-for-Others contract (no. ERD-92-1132), which began May 24, 1993, ORNL was tasked to determine the feasibility of applying the CEUSP (or a similar) calcination process to solidify AECL's 99Mo waste for > 30 years of safe dry storage. This study was to provide sufficient detailed information on the applicability of a CEUSP-type waste solidification process to allow AECL to select the process which best suited its needs. As with the CEUSP process, evaporation of the waste and a simultaneously partial destruction of acid by reaction with formaldehyde followed by in situ waste can thermal denitration waste was chosen as the best means of solidification. Unlike the CEUSP material, the 99Mo waste has a considerable number of problem volatile and semivolatile constituents which must be recovered in the off-gas treatment system. Mercury removal before calcination was seen as the best option

  4. Synthesis of Cd/(Al+Fe) layered double hydroxides and characterization of the calcination products

    International Nuclear Information System (INIS)

    Layered double hydroxides (LDHs) containing Cd(II), Al(III), and Fe(III) in the brucite-like layers with different starting Fe/Al atomic ratios and with nitrate as counteranion have been prepared following the coprecipitation method at a constant pH value of 8. An additional Cd(II),Al(III)-LDH sample interlayered with hexacyanoferrate(III) ions has been prepared by ionic exchange at pH 9. The samples have been characterized by elemental chemical analysis, powder X-ray diffraction (PXRD), and FT-IR spectroscopy. Their thermal stability has been assessed by thermogravimetric and differential thermal analyses (TG-DTA) and mass spectrometric analysis of the evolved gases. The PXRD patterns of the solids calcined at 800 deg. C show diffraction lines corresponding to Cd(Al)O and spinel-type materials, which precise nature (CdAl2O4, Cd1-xFe2+xO4, or CdxFe2.66O4) depends on location and concentration of iron in the parent material or precursor. - Graphical abstract: Layered double hydroxides (LDHs) containing Cd(II), Al(III), and Fe(III) in the brucite-like layers with different starting Fe/Al atomic ratios and with nitrate as counteranion have been prepared following the coprecipitation method. An additional Cd(II),Al(III)-LDH sample interlayered with hexacyanoferrate(III) ions has been prepared by ionic exchange. Calcination at 800 deg. C shows diffraction lines corresponding to CdO and to spinel-type materials. SEM micrograph of sample CdAlFe-N-0

  5. Genesis of Cr(VI) in Sri Lankan soils and its adsorptive removal by calcined gibbsite

    Science.gov (United States)

    Rajapaksha, A. U.; Wijesundara, D. M.; Vithanage, M. S.; Ok, Y. S.

    2012-12-01

    Hexavalent chromium is highly toxic to biota and considered as a priority pollutant. Industrial sources of Cr(VI) include leather tanning, plating, electroplating, anodizing baths, rinse waters, etc. In addition, weathering of ultramafic rocks rich in chromium, such as serpentine, is known to Cr(VI) sources into natural water. The Cr(III) is the most stable in the environment, however, conversion of Cr(III) into Cr(VI) occurs in soil due to presence of naturally occurring minerals such as manganese dioxides. We investigated the amount of Cr(VI) recorded from the soils from anthropogenically and naturally contaminated soils (serpentine soils) in Sri Lanka and the removal efficacy of Cr(VI) by calcined gibbsite (Al oxides). The effect of pH on Cr(VI) adsorption was determined by adjusting the pH in the range of 4-10. In the experiments, the adsorbent concentration was kept at 1 g/l of solution containing 10 mg/l Cr(VI) at 25 0C. Total chromium recorded were around 11,000 mg kg-1 and 6,000 mg kg-1 for serpentine soil and tannery waste-contaminated soil, respectively. Although total Cr was high in the contaminated soils, Cr(VI) concentration was only about 28 mg kg-1 and 210 mg kg-1 in the serpentine and tannery soils, respectively. The calcined gibbsite has maximum adsorption of 85 % around pH 4 and adsorption generally decreased with increase of pH.

  6. Chemistry of application of calcination/dissolution to the Hanford tank waste inventory

    International Nuclear Information System (INIS)

    Approximately 330,000 metric tons of sodium-rich radioactive waste originating from separation of plutonium from irradiated uranium fuel are stored in underground tanks at the Hanford Site in Washington State. Fractionation of the waste into low-level waste (LLW) and high-level waste (HLW) streams is envisioned via partial water dissolution and limited radionuclide extraction operations. Under optimum conditions, LLW would contain most of the chemical bulk while HLW would contain virtually all of the transuranic and fission product activity. Calcination at around 850 C, followed by water dissolution, has been proposed as an alternative initial treatment of Hanford Site waste to improve waste dissolution and the envisioned LLW/HLW split. Results of literature and laboratory studies are reported on the application of calcination/dissolution (C/D) to the fractionation of the Hanford Site tank waste inventory. Both simulated and genuine Hanford Site waste materials were used in the lab tests. To evaluation confirmed that C/D processing reduced the amount of several components from the waste. The C/D dissolutions of aluminum and chromium allow redistribution of these waste components from the HLW to the LLW fraction. Comparisons of simple water-washing with C/D processing of genuine Hanford Site waste are also reported based on material (radionuclide and chemical) distributions to solution and solid residue phases. The lab results show that C/D processing yielded superior dissolution of aluminum and chromium sludges compared to simple water dissolution. 57 refs., 26 figs., 18 tabs

  7. Test plan for non-radioactive testing of vertical calciner for development of direct denitration conversion of Pu-bearing liquors to stable, storage solids

    International Nuclear Information System (INIS)

    Plutonium-bearing liquors, including ANL scrap liquors, will be used for development and demonstration of a vertical calciner direct denitration process for conversion of those liquors to stable, storable PuO2-rich solids. This test plan is to test with non-radioactive stand-in materials to demonstrate adequate performance of the vertical calciner and ancillary equipment

  8. Stabilized γ-BIMNVOX solid electrolyte: Ethylene glycol–citrate sol–gel synthesis, microwave-assisted calcination, and structural and electrical characterization

    Energy Technology Data Exchange (ETDEWEB)

    Al-Areqi, Niyazi A.S., E-mail: niyazi.alareqi@gmail.com [Department of Chemistry, Faculty of Applied Science, Taiz University, Taiz, Republic of Yemen (Yemen); Beg, Saba [Department of Chemistry, Aligarh Muslim University, Aligarh 202002 (India); Al-Alas, Ahlam [Department of Chemistry, Faculty of Applied Science, Taiz University, Taiz, Republic of Yemen (Yemen); Hafeez, Shehla [Department of Chemistry, Aligarh Muslim University, Aligarh 202002 (India)

    2013-12-25

    Highlights: •γ-BIMNVOX was synthesized by ethylene glycol–citrate sol–gel route. •γ-BIMNVOX crystallizes by 25-min microwave-assisted calcination. •Smaller particle sizes for microwave calcined BIMNVOX samples. •Best oxide-ion performance for microwave calcined BIMNVOX samples. -- Abstract: Samples of γ-BIMNVOX (Bi{sub 2}V{sub 1−x}Mn{sub x}O{sub 5.5−x/2}; 0.13 ⩽ x ⩽ 0.20) system were synthesized by an ethylene glycol–citrate sol–gel route. The resulting xerogels were then calcined by the microwave heating using a modified domestic microwave oven operated at 2.45 GHz. Microwave-assisted calcination samples in comparison with other conventionally calcined samples were characterized in terms of phase crystallization, stabilization and particle size using simultaneous thermogravimetric–differential thermal analysis (TG–DTA), X-ray powder diffraction (XRPD) and scanning electron microscopy (SEM). The AC impedance spectroscopy was employed for electrical characterization. It was found that the microwave-assisted calcination route successfully produces better crystalline stabilized γ-BIMNVOX samples with appreciably small average particle sizes after only 25 min of microwave heating. The electrical properties of microwave calcined γ-BIMNVOX system make it an advanced low-temperature solid electrolyte suitable for use in oxide-ion based electrochemical applications.

  9. To study the effect of dopant NiO concentration and duration of calcinations on structural and optical properties of MgO-NiO nanocomposites

    Science.gov (United States)

    Kumar, Rajesh; Praveen, Sharma, Ashwani; Parmar, R.; Dahiya, S.; Kishor, N.

    2016-05-01

    In present work Magnesium oxide (MgO) samples were doped with different concentration of Transition metal Nickel Oxide(NiO) by using Chemical co-precipitation method. The doping levels were varied from NiO (5%, 10%, 15%) and all the samples were calcined at 600°C for 4hrs and 8hrs respectively. Structural analysis of these calcined materials is carried out by X-ray diffraction (XRD) techniques which reveals that average crystalline sizes are in nano region i.e. 21.77nm-31.13 nm and tabulated in table 1. The powder of calcined samples were also characterized by using various other techniques i.e. Scanning Electron Microscopy (SEM), Fourier Transformation Infrared Spectroscopy (FTIR), UV-Visible spectroscopy, Transmission Electron Microscopy (TEM) etc. The effects of dopant concentration, calcined temperature, calcinations duration on samples were studied and also investigate the effect of varying dopant concentration on morphology and optical properties of calcined nanomaterials. From results it was observed that the crystallite size of nanocomposites increases with increases dopant concentration or increases calcinations duration. The optical band gap decreases with increases sintering time and increase with increases dopant concentrations. TEM results coincide with XRD results and show that particles are polycrystalline in nature. FTIR spectra show that for all samples particles are pure in composition and transmission rate increases with calcinations duration.

  10. Influence of calcination temperature on sol-gel synthesized single-phase bismuth titanate for high dielectric capacitor applications

    Energy Technology Data Exchange (ETDEWEB)

    Thiruramanathan, Pandirengan; Marikani, Arumugam [Mepco Schlenk Engineering College, Tamil Nadu (India). Dept. of Physics; Madhavan, Durairaj [Mepco Schlenk Engineering College, Tamil Nadu (India). Dept. of Chemistry; Bharadwaj, Suresh; Awasthi, Anand Mohan [UGC-DAE Consortium for Scientific Research, Indore (India). Thermodynamics Lab.

    2016-05-15

    An inexpensive sol-gel combustion method using citric acid as fuel has been used to synthesize bismuth titanate, Bi{sub 4}Ti{sub 3}O{sub 12} nanopowders. Thermogravimetric analysis proved that a calcination temperature of 900 C is sufficient for the preparation of single-phase bismuth titanate. X-ray diffraction and Fourier transform infrared spectroscopy are used to examine the influence of calcination temperature on the structural growth of the Bi{sub 4}Ti{sub 3}O{sub 12} nanopowder. The average crystallite size estimated by using the Scherrer method and the Williamson-Hall method was found to increase with calcination temperature. Photoluminescence behavior as a function of calcination temperature was observed at two different excitation wavelengths of 300 nm and 420 nm. The morphology of the particles analyzed using images obtained from field emission scanning electron microscopy displayed irregular, random sized, and spherical-shaped structures. The stoichiometry and purity of the nanopowder are confirmed by energy-dispersive spectroscopy. The broadband dielectric results established the highest dielectric constant (ε{sub r} = 450) for a frequency of 100 Hz achieved with a potential capacitance of 138 pF m{sup -2}. This establishes Bi{sub 4}Ti{sub 3}O{sub 12} as a promising dielectric material for achieving high energy density capacitors for the next-generation passive devices.

  11. Effect of calcination temperature and reaction conditions on methane partial oxidation using lanthanum-based perovskite as oxygen donor

    Institute of Scientific and Technical Information of China (English)

    DAI Xiaoping; YU Changchun; LI Ranjia; WU Qiong; SHI Kaijiao; HAO Zhengping

    2008-01-01

    We investigated the effect of calcination temperature, reaction temperature, and different amounts of replenished lattice oxygen on the partial oxidation of methane (POM) to synthesis gas using perovskite-type LaFeO3 oxide as oxygen donor instead of gaseous oxygen, which was prepared by the sol-gel method, and the oxides were characterized by XRD, TG/DTA, and BET. The results indicated that the particle size increased with the calcination temperature increasing, while BET and CH4 conversion declined with the calcination temperature increasing using LaFeO3 oxide as oxygen donor in the absence of gaseous oxygen. CO selectivity remained at a high level such as above 92%, and increased slightly as the calcination temperature increased. Exposure of LaFeO3 oxides to methane atmosphere enhanced the oxygen migration of in the bulk with time online owing to the loss of lattice oxygen and reduction of the oxidative stated Fe ion simultaneously. The high reaction temperature was favorable to the migration of oxygen species from the bulk toward the surface for the synthesis gas production with high CO selectivity. The product distribution and evolution for POM by sequential redox reaction was determined by amounts of replenished lattice oxygen with gaseous oxygen. The optimal process should decline the total oxidation of methane, and increase the selectivity of partial oxidation of methane.

  12. CALCINATION AND SINTERING MODELS FOR APPLICATION TO HIGH-TEMPERATURE, SHORT-TIME SULFATION OF CALCIUM-BASED SORBENTS

    Science.gov (United States)

    To simulate the staged availability of transient high surface area CaO observed in high-temperature flow-reactor data, the rate of calcination of CaCO3 or Ca(OH)2 is described by an empirical modification of the shrinking-core model. The physical model depicts particle decomposi...

  13. Description of a pilot plant to produce a pelleted form from simulated ICPP high-level calcined wastes

    International Nuclear Information System (INIS)

    The pilot plant uses techniques learned in the laboratory to combine calcine with solid and liquid binders to form hard, leach-resistant pellets. The pilot plant is designed to process up to 25 kg/h of calcine and will provide information necessary to verify the operational feasibility of pelletizing calcined waste. Also, information for the design of a possible full-scale pelletizing plant will be obtained. All components of the pelletizing operations are described. The solids feed system consists of two loss-in-weight feeders: one for calcine and one for solid binders. Intimate mixing of the solids is accomplished in a screw mixer-feeder. A metering pump is used to pump liquid binders to the pelletizer through a spray nozzle. A 12.7 mm mesh, vibro screen separator removes oversize pellets, leaving the pelletizer. A 0-6 kW microwave-heated dryer operating at 150 to 2000C removes moisture from the pellets in about 15 minutes. To impart leach resistance, the pellets are heat treated at 800 to 9000C for 1 to 2 hrs in a kiln. Pellets move down through a set of 6 to 8 stacked, rotating trays inside the kiln. Pellets are collected from the heat treater and tested for strength and leach resistance. An off-gas system cools and removes dust present in the off-gas from the pilot plant. 20 figures

  14. Influence of calcinations temperature on physical properties of the nanocomposites containing spinel and CuO phases

    Energy Technology Data Exchange (ETDEWEB)

    Srivastava, Manish [Department of Physics, Motilal Nehru National Institute of Technology, Allahabad, Allahabad 211004 (India); Ojha, Animesh K., E-mail: animesh_r1776@rediffmail.co [Department of Physics, Motilal Nehru National Institute of Technology, Allahabad, Allahabad 211004 (India); Chaubey, S. [Department of Physics, Motilal Nehru National Institute of Technology, Allahabad, Allahabad 211004 (India); Sharma, Prashant K.; Pandey, Avinash C. [Nanophosphor Application Centre, University of Allahabad, Allahabad 211002 (India)

    2010-04-02

    Nanocomposites containing spinel and CuO phases have been synthesized by sol-gel method using Cu(II), Ni(II) and Fe(III) in a basic medium. The effect of calcinations temperature on the physical properties of the nanocomposites has been investigated by X-ray diffraction (XRD), Fourier transform infrared (FT-IR), micro-Raman spectroscopy (RS), differential scanning calorimetery (DSC)/thermogravemetric analysis (TGA), diffuse reflectance spectroscopy (DRS), scanning electron microscope (SEM), high resolution transmission electron microscope (HR-TEM) and vibrating sample magnetometer (VSM). The XRD pattern of nanocomposites synthesized at different calcinations temperature reveals spinel and CuO phases. The particle size of the nanocomposites is increasing with increasing the calcinations temperature. The band gap of synthesized nanocomposites has been calculated using DRS method. The prepared nanocomposites exhibit semiconducting nature with band gap values, 1.9-2.24 eV. The magnetic properties of nanocomposites are also measured at room temperature and the values of saturation magnetization (Ms), remanent magnetization (Mr) and coercivity are found enhanced with the calcinations temperature.

  15. Development and Testing of the Advanced CHP System Utilizing the Off-Gas from the Innovative Green Coke Calcining Process in Fluidized Bed

    Energy Technology Data Exchange (ETDEWEB)

    Chudnovsky, Yaroslav; Kozlov, Aleksandr

    2013-08-15

    Green petroleum coke (GPC) is an oil refining byproduct that can be used directly as a solid fuel or as a feedstock for the production of calcined petroleum coke. GPC contains a high amount of volatiles and sulfur. During the calcination process, the GPC is heated to remove the volatiles and sulfur to produce purified calcined coke, which is used in the production of graphite, electrodes, metal carburizers, and other carbon products. Currently, more than 80% of calcined coke is produced in rotary kilns or rotary hearth furnaces. These technologies provide partial heat utilization of the calcined coke to increase efficiency of the calcination process, but they also share some operating disadvantages. However, coke calcination in an electrothermal fluidized bed (EFB) opens up a number of potential benefits for the production enhancement, while reducing the capital and operating costs. The increased usage of heavy crude oil in recent years has resulted in higher sulfur content in green coke produced by oil refinery process, which requires a significant increase in the calcinations temperature and in residence time. The calorific value of the process off-gas is quite substantial and can be effectively utilized as an “opportunity fuel” for combined heat and power (CHP) production to complement the energy demand. Heat recovered from the product cooling can also contribute to the overall economics of the calcination process. Preliminary estimates indicated the decrease in energy consumption by 35-50% as well as a proportional decrease in greenhouse gas emissions. As such, the efficiency improvement of the coke calcinations systems is attracting close attention of the researchers and engineers throughout the world. The developed technology is intended to accomplish the following objectives: - Reduce the energy and carbon intensity of the calcined coke production process. - Increase utilization of opportunity fuels such as industrial waste off-gas from the novel

  16. Studies on recycled aggregates-based concrete.

    Science.gov (United States)

    Rakshvir, Major; Barai, Sudhirkumar V

    2006-06-01

    Reduced extraction of raw materials, reduced transportation cost, improved profits, reduced environmental impact and fast-depleting reserves of conventional natural aggregates has necessitated the use of recycling, in order to be able to conserve conventional natural aggregate. In this study various physical and mechanical properties of recycled concrete aggregates were examined. Recycled concrete aggregates are different from natural aggregates and concrete made from them has specific properties. The percentages of recycled concrete aggregates were varied and it was observed that properties such as compressive strength showed a decrease of up to 10% as the percentage of recycled concrete aggregates increased. Water absorption of recycled aggregates was found to be greater than natural aggregates, and this needs to be compensated during mix design. PMID:16784165

  17. Diversity, intent, and aggregated search

    NARCIS (Netherlands)

    M. de Rijke

    2014-01-01

    Diversity, intent and aggregated search are three core retrieval concepts that receive significant attention. In search result diversification one typically considers the relevance of a document in light of other retrieved documents. The goal is to identify the probable "aspects" of an ambiguous que

  18. Child Labor and Aggregate Fluctuations

    OpenAIRE

    Stéphane Pallage; Alice Fabre

    2010-01-01

    In this paper, we build a dynamic general equilibrium model with heterogeneous agents to measure the welfare effect of banning child labor in an economy with aggregate fluctuations and idiosyncratic shocks to employment. We then design an unemployment insurance system that generates the endogenous elimination of child labor.

  19. Using Information Aggregation Markets for Decision Support

    Directory of Open Access Journals (Sweden)

    Patrick Buckley

    2012-06-01

    Full Text Available Information Aggregation Markets, often referred to as prediction markets, are markets that are designed to aggregate information from a disparate pool of human individuals to make predictions about the likely outcome of future uncertain events. This paper looks at how Information Aggregation Markets can be incorporated into the standard body of decision making theory. It examines how Information Aggregation Markets can be used as decision support systems, and provides empirical evidence from a wide variety of sources as to the effectiveness and practicality of Information Aggregation Markets. Finally, this paper details some future research questions to be addressed in the area of Information Aggregation Markets.

  20. Reduction of Acute Inflammatory Effects of Fumed Silica Nanoparticles in the Lung by Adjusting Silanol Display through Calcination and Metal Doping.

    Science.gov (United States)

    Sun, Bingbing; Pokhrel, Suman; Dunphy, Darren R; Zhang, Haiyuan; Ji, Zhaoxia; Wang, Xiang; Wang, Meiying; Liao, Yu-Pei; Chang, Chong Hyun; Dong, Juyao; Li, Ruibin; Mädler, Lutz; Brinker, C Jeffrey; Nel, André E; Xia, Tian

    2015-09-22

    The production of pyrogenic (fumed) silica is increasing worldwide at a 7% annual growth rate, including expanded use in food, pharmaceuticals, and other industrial products. Synthetic amorphous silica, including fumed silica, has been generally recognized as safe for use in food products by the Food and Drug Administration. However, emerging evidence from experimental studies now suggests that fumed silica could be hazardous due to its siloxane ring structure, high silanol density, and "string-of-pearl-like" aggregate structure, which could combine to cause membrane disruption, generation of reactive oxygen species, pro-inflammatory effects, and liver fibrosis. Based on this structure-activity analysis (SAA), we investigated whether calcination and rehydration of fumed silica changes its hazard potential in the lung due to an effect on silanol density display. This analysis demonstrated that the accompanying change in surface reactivity could indeed impact cytokine production in macrophages and acute inflammation in the lung, in a manner that is dependent on siloxane ring reconstruction. Confirmation of this SAA in vivo, prompted us to consider safer design of fumed silica properties by titanium and aluminum doping (0-7%), using flame spray pyrolysis. Detailed characterization revealed that increased Ti and Al doping could reduce surface silanol density and expression of three-membered siloxane rings, leading to dose-dependent reduction in hydroxyl radical generation, membrane perturbation, potassium efflux, NLRP3 inflammasome activation, and cytotoxicity in THP-1 cells. The reduction of NLRP3 inflammasome activation was also confirmed in bone-marrow-derived macrophages. Ti doping, and to a lesser extent Al doping, also ameliorated acute pulmonary inflammation, demonstrating the possibility of a safer design approach for fumed silica, should that be required for specific use circumstances. PMID:26200133

  1. Effect of calcination temperature on structural and photocatalyst properties of nanofibers prepared from low-cost natural ilmenite mineral by simple hydrothermal method

    Energy Technology Data Exchange (ETDEWEB)

    Simpraditpan, Athapon [College of Nanotechnology, King Mongkut' s Institute of Technology Ladkrabang, Ladkrabang, Bangkok 10520 (Thailand); Wirunmongkol, Thanakorn [Department of Materials and Metallurgical Engineering, Faculty of Engineering, Rajamangala University of Technology Thanyaburi, Klong 6, Pathumthani 12110 (Thailand); Pavasupree, Sorapong, E-mail: sorapongp@yahoo.com [Department of Materials and Metallurgical Engineering, Faculty of Engineering, Rajamangala University of Technology Thanyaburi, Klong 6, Pathumthani 12110 (Thailand); Pecharapa, Wisanu [College of Nanotechnology, King Mongkut' s Institute of Technology Ladkrabang, Ladkrabang, Bangkok 10520 (Thailand); Thailand and Center of Excellence in Physics (ThEP Center), Commission on Higher Education, 328 Si Ayutthaya Rd., Bangkok 10400 (Thailand)

    2013-09-01

    Graphical abstract: - Highlights: • Nanofibers were prepared from low-cost ilmenite mineral via simple hydrothermal. • High photocatalyst nanofibers were prepared via post heat treatment method. • The nanofibers calcined at 100–700 °C for 2 h maintained nanofiber structure. • The calcined nanofibers at 400 °C showed the highest photocatalytic activity. - Abstract: Titanate nanofibers were synthesized via the hydrothermal method (120 °C for 72 h) using natural ilmenite mineral (FeTiO{sub 3}) as the starting material. The samples were characterized by X-ray diffraction (XRD), X-ray fluorescent (XRF), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and Brunauer–Emmett–Teller (BET) for specific surface area. The nanofibers were 20–90 nm in diameter and 2–7 μm in length. The as-synthesized nanofibers calcined at 300–400 °C showed TiO{sub 2} (B) whereas the nanofibers calcined at 500 °C revealed a mixture of two phases of TiO{sub 2} (B) and anatase. The nanofibers calcined at high temperature of 600–1000 °C showed a mixture of tri-crystalline of anatase, rutile, and Fe{sub 2}O{sub 3}. The rutile phase increased with increasing calcination temperature. The nanofibers calcined at 300–700 °C maintained their structure while the morphology of the nanofibers calcined at 800–1000 °C transformed into submicron rod-like structure. This increase of calcination temperature led to the phase transformation from thermodynamically metastable anatase to the most stable form of rutile phase. The crystallite size of prepared samples increased with increasing calcination temperature. Interestingly, with increasing calcination temperature, the absorption edge of the prepared samples shows an obvious shift to visible light region due to the change of crystallite phase and increased crystallite size. Therefore, the band gap energy of the prepared samples became narrower with increasing calcination temperature. Furthermore, the

  2. Synthesis and characterization of nanocrystalline hydroxyapatite gel and its application as scaffold aggregation

    Directory of Open Access Journals (Sweden)

    Leonardo Ribeiro Rodrigues

    2012-12-01

    Full Text Available The sol-gel process is a technique used to synthesize materials from colloidal suspensions and, therefore, is suitable for preparing materials in the nanoscale. In this work hydroxyapatite was used due to its known properties in tissue engineering. Hydroxyapatite Ca10(PO46(OH2 is a bioactive ceramic which is found in the mineral phase of bone tissue and is known for its great potential in tissue engineering applications. For this reason, this material can be applied as particle aggregates on ceramic slurry, coating or film on materials with a poorer biological response than hydroxyapatite. In this work, hydroxyapatite gel was obtained by the sol-gel process and applied as nanoparticle aggregation in the mixture of hydroxyapatite and tricalcium phosphate to form a ceramic slurry. This process is the polymer foam replication technique used to produce scaffolds, which are used in tissue engineering. For HA gel characterization it was used enviromental scanning electron microscopy (ESEM, transmission electron microscopy (TEM, electron energy loss spectroscopy (EELS, scanning electron microscopy (SEM, X-ray diffraction (XRD and X-ray fluorescence (XRF. The crystallite size was calculated from XRD data using the Scherrer equation. The nanoparticles size before firing was approximately 5nm. The crystallite size calculated after calcination was approximately 63 nm. The EELS results showed that calcium phosphate was obtained before firing. After HA gel calcination at 500 ºC the XRD results showed hydroxyapatite with a small content of beta-TCP. The scaffolds obtained by polymer foam replication technique showed a morphology with adequate porosity for tissue engineering.

  3. Pilot-Plant Studies of the Fluidized-Bed Waste Calcination Process

    International Nuclear Information System (INIS)

    Studies have been conducted in 6- and 12-in diam. electrically heated fluidized beds and in a 24-in square NaK-heated bed and are being extended in the two larger units. Although exploratory studies demonstrated the feasibility of this process for stainless steel and zirconium fuel wastes, the overwhelming majority of the work has been with aluminium fuel wastes. Feed rates from 5 to 150 1/hr per air-atomizing nozzle have been used with no perceptible tendency toward caking, capacity of all units has been limited by the rate of heat introduction through internal surfaces. Measured heat-transfer coefficients range from 40 to 110 BTU/(hr)(°F) (ft2), depending upon bed particle size and fluidized-bed density. Particle size has been controlled by varying the atomizing air rate, the major factor governing particle attrition; quantitatively this effect is very dependent on the crystalline form of alumina produced. Various operating factors make significant differences in the rate of conversion of amorphous alumina calcine to the alpha (or, in isolated cases, gamma or iota) crystalline form. Particle attrition increases with alpha alumina content; hence, average bed particle size decreases and particle elutriation rate increases with increasing alpha content. High alpha-content beds are more dense and contain less nitrate, both desirable features. Sodium is a necessary feed ingredient for alpha alumina formation; its effect can be overcome by addition of boric acid to the feed. Addition of one of these components to the feed is recommended to obtain the desired product form. Intra-particle porosity varies from 5 to 60% and is a direct function of bed temperature (from 250 to 550°C) and feed concentration (from 0, 8 to 2.0M aluminium), but not a significant function of any other variable. Superficial fluidizing velocities from 0.5 to 2.5 ft/sec have been used; best results are obtained with velocities under 1.0 ft/sec. Studies have been made with and without condensing

  4. Economic Evaluation of Tank Storage and Pot Calcination of Power-Reactor Fuel-Reprocessing Wastes

    International Nuclear Information System (INIS)

    As part of a comprehensive study undertaken to evaluate the economics and hazards associated with methods for ultimate disposal of highly radioactive liquid and solid wastes, costs have been estimated for interim storage of the wastes in tanks and conversion to solids by pot calcination. A 6-t(metric)/d capacity fuel-processing plant was assumed, processing 1500 t/yr of uranium fuel of 10 000-MWd/t bum-up and 270 t/yr of thorium fuel of 20 000-MWd/t burn-up, which would process all the fuel from a 15 000-MWe nuclear economy. Costs for storage of acidic and neutralized Purex and Thorex wastes were estimated for storage in stainless- steel tanks for acidic wastes and mild steel for neutralized waste. With interim storage time defined as filling time plus full time, tank costs were minimum when the full time was roughly 40 to 75% of the interim storage time. For 0.5 - 30 yr storage, costs ranged from 2.0 x 10-3 to 9.3 x 10-3 mill/kWhe for acid wastes and from 1.5 x 10-3 to 4.7 x 10-3 mill/kWhe for alkaline wastes. Costs were estimated for converting acidic and reacidified Purex and Thorex wastes to solids by pot calcination and for producing glass from acidic Thorex wastes. The vessels studied were made of 6-, 12-, and 24-in-diam. stainless-steel pipe, 10 ft high, with estimated costs of $500, $855 and $2515. Aging had negligible effect on costs for processing in a vessel of a given size, because capital costs were only about 10% of vessel and operating costs, but permitted larger vessels to be used; costs for processing in 6-in-diam. vessels were two to three times those in 24-in-diam.vessels. The lowest cost was 0.87 x 10-2 mill/kWhe for processing-acidic Purex and .Thorex wastes in 24-in-diam. vessels and the highest was 5.0 x 10-2 mill/kWhe for processing reacidified Purex and Thorex wastes in 6-in-diam. vessels. (author)

  5. Estimation of line efficiency by aggregation

    OpenAIRE

    Koster, de, MBM René

    1987-01-01

    textabstractPresents a multi-stage flow lines with intermediate buffers approximated by two-stage lines using repeated aggregation. Characteristics of the aggregation method; Problems associated with the analysis and design of production lines.

  6. Aggregation of metallochlorophylls - Examination by spectroscopy

    Science.gov (United States)

    Boucher, L. J.; Katz, J. J.

    1969-01-01

    Nuclear magnetic resonance measurements determine which metallochlorophylls, besides magnesium-containing chlorophylls, possess coordination aggregation properties. Infrared spectroscopy reveals that only zinc pheophytin and zinc methyl pheophorbide showed significant coordination aggregation, whereas divalent nickel and copper did not.

  7. Yeast prions: protein aggregation is not enough.

    OpenAIRE

    Sherman, Michael Y

    2004-01-01

    Although many proteins -- both damaged and normal -- have a tendency to aggregate, only some are capable of dividing and propagating. What does it take to turn a protein aggregate into an infectious prion?

  8. Estimation of Line Efficiency by Aggregation

    NARCIS (Netherlands)

    M.B.M. de Koster (René)

    1987-01-01

    textabstractPresents a multi-stage flow lines with intermediate buffers approximated by two-stage lines using repeated aggregation. Characteristics of the aggregation method; Problems associated with the analysis and design of production lines.

  9. Elections, information aggregation, and strategic voting

    OpenAIRE

    Feddersen, Timothy; Pesendorfer, Wolfgang

    1999-01-01

    A central role of elections is the aggregation of information dispersed within a population. This article surveys recent work on elections as mechanisms for aggregating information and on the incentives for voters to vote strategically in such elections.

  10. Bacterial Association with Particles: Aggregation to Dissolution

    Digital Repository Service at National Institute of Oceanography (India)

    DeSouza, M.J.B.D.

    stick to phytoplankton cells to form larger particles called marine snow that enhance the sinking flux of organic carbon. However, Smith et al. (1992) and Ploug et al. (1999) found that once the bacteria colonize the aggregate they solubilize... trophic levels of the aquatic food web (Kiorboe et al., 2002). Caron et al. (1982) thought that aggregates are important loci of microbial activity in the water column, similar to the much larger oceanic ?marine snow? aggregates. Marine snow aggregates...

  11. ASSESSMENT OF FINE RECYCLED AGGREGATES IN MORTAR

    OpenAIRE

    Feys, Charles; Joseph, Miquel; Boehme, Luc; Zhang, Yunlian

    2016-01-01

    In this study, the influence of fine recycled concrete aggregates as replacement for sand in mortar and the use as cement replacement and filler is investigated. Mortar with fine recycled aggregates is examined on its mechanical and physical properties. The samples are also examined on a microscopic scale. The fine recycled concrete aggregates are made with one-year old concrete made in the laboratory. Fine recycled aggregates (FRCA) are added as a cement replacement (0 %, 10 %...

  12. Revisiting Aggregation Techniques for Data Intensive Applications

    OpenAIRE

    Wen, Jian

    2013-01-01

    Aggregation has been an important operation since the early days of relational databases. Today's Big Data applications bring further challenges when processing aggregation queries, demanding robust aggregation algorithms that can process large volumes of data efficiently in a distributed, share-nothing architecture. Moreover, aggregation on each node runs under a potentially limited memory budget (especially in multiuser settings). Despite its importance, the design and evaluation of aggrega...

  13. Computers and Productivity: Are Aggregation Effects Important?

    OpenAIRE

    Robert H. McGuckin; Kevin Stiroh

    2000-01-01

    This paper examines the empirical implications of aggregation bias when measuring the productive impact of computers. To isolate two specific aggregation problems relating to "aggregation in variables" and "aggregation in relations," we compare various production function estimates across a range of specifications, econometric estimators, and data levels. The results show that both sources of bias are important, especially as one moves from the sector to the economy level, and when the elasti...

  14. Internal water curing with Liapor aggregates

    DEFF Research Database (Denmark)

    Lura, Pietro

    2005-01-01

    Internal water curing is a very efficient way to counteract self-desiccation and autogenous shrinkage in high performance concrete, thereby reducing the likelihood of early-age cracking. This paper deals with early-age volume changes and moisture transport in lightweight aggregate concrete realized...... with wet lightweight aggregates. Lightweight aggregate concrete mixtures with different degree of saturation and different particle size of the lightweight aggregates were studied and compared to normal weight concrete. Autogenous deformations, selfinduced stresses in fully restrained conditions...

  15. Aggregation resistant zwitterated superparamagnetic nanoparticles

    International Nuclear Information System (INIS)

    Superparamagnetic nanoparticles (NPs) are promising for biomedical applications since they can be directed toward the organ of interest using an external magnetic field. They are also good contrast agents for magnetic resonance imaging and have potential for the treatment of malignant tumors (i.e., hyperthermia). Therefore, there is a need to produce stable, non-aggregating superparamagnetic nanomaterials that can withstand the in vivo environment. In this work, the colloidal stability of a dispersion of iron oxide NPs was enhanced by functionalizing them with a short zwitterionic siloxane shell in aqueous media. The stabilization procedure yields superparamagnetic nanomaterials, ca. 10 nm in diameter, with saturation magnetization of about 54 emu/g that resist aggregation at physiological salt concentration, temperature, and pH. The loading of the zwitterionic shell was established with diffuse reflectance infrared spectroscopy and thermal gravimetric analysis. X-ray and electron diffraction verified the starting magnetite phase, and that no change in phase occurred on surface functionalization.

  16. Aggregating and Disaggregating Flexibility Objects

    DEFF Research Database (Denmark)

    Siksnys, Laurynas; Valsomatzis, Emmanouil; Hose, Katja;

    2015-01-01

    In many scientific and commercial domains we encounter flexibility objects, i.e., objects with explicit flexibilities in a time and an amount dimension (e.g., energy or product amount). Applications of flexibility objects require novel and efficient techniques capable of handling large amounts...... of such objects while preserving flexibility. Hence, this paper formally defines the concept of flexibility objects (flex-objects) and provides a novel and efficient solution for aggregating and disaggregating flex-objects. Out of the broad range of possible applications, this paper will focus on smart grid...... energy data management and discuss strategies for aggregation and disaggregation of flex-objects while retaining flexibility. This paper further extends these approaches beyond flex-objects originating from energy consumption by additionally considering flex-objects originating from energy production...

  17. Containing Internal Diffusion Limited Aggregation

    CERN Document Server

    Duminil-Copin, Hugo; Yadin, Ariel; Yehudayoff, Amir

    2011-01-01

    Internal Diffusion Limited Aggregation (IDLA) is a model that describes the growth of a random aggregate of particles from the inside out. Shellef proved that IDLA processes on supercritical percolation clusters of integer-lattices fill Euclidean balls, with high probability. In this article, we complete the picture and prove a limit-shape theorem for IDLA on such percolation clusters, by providing the corresponding upper bound. The technique to prove upper bounds is new and robust: it only requires the existence of a "good" lower bound. Specifically, this way of proving upper bounds on IDLA clusters is more suitable for random environments than previous ways, since it does not harness harmonic measure estimates.

  18. Phase and morphology evolution of (Na1-xKxNbO3 powders related to calcinations and K2CO3 content

    Directory of Open Access Journals (Sweden)

    Steven J. Milne

    2007-03-01

    Full Text Available Sodium-potassium niobate ((Na1-xKxNbO3 powders with x = 0.2, 0.4, 0.6 and 0.8 were prepared following the conventional mixed oxide method and characterized by TG-DTA, XRD and SEM techniques.The effects of calcination temperature, dwell time and K2CO3 content on phase formation behavior and morphology of the powders were investigated. The calcination temperature and dwell time were found tohave a pronounced effect on the phase formation of the calcined sodium-potassium niobate powders. It was found that the crystallized phase depended on calcination conditions. The high calcination temperature andlong dwell time clearly favored particle growth and the formation of large and hard agglomerates. All the (Na1-xKxNbO3 powders showed a similar orthorhombic phase structure. The K2CO3 content significantlyaffected the calcination temperature and particle size and shape. Large particle size, cubic shape and a lower calcined condition were observed in (Na1-xKxNbO3 powder with low K2CO3 content (x = 0.2.

  19. Effect of calcining temperature and time on the characteristics of Sb-doped SnO2 nanoparticles synthesized by the sol-gel method

    Institute of Scientific and Technical Information of China (English)

    Xiaohua Zhong; Baoping Yang; Xiaoliang Zhang; Junhong Jia; Gewen Yi

    2012-01-01

    Spherical Sb-doped SnO2 (ATO) nanoparticles were synthesized by the sol-gel route,employing SnCl4·5H2O and SbCl3 as precursors in an ethanol solution.The influences of the calcining temperature and calcining time on the crystallite size,crystallinity,lattice parameters,lattice distortion ratio and the resistivity of the ATO nanoparticles were synthetically investigated.The results suggested that the ATO nanoparticles were crystallized in a tetragonal cassiterite structure of SnO2 with a highly (110)-plane-preferred orientation.The calcining temperature had a dominating effect on the crystallite size,crystallinity,lattice distortion ratios and resistivity of the ATO.As the calcining temperature increased,the average crystallite size increased,the crystallinity was promoted accompanied by a decrease in the lattice distortion ratio and a corresponding decrease in the resistivity of the ATO.X-ray diffraction (XRD) and Fourier transform infrared spectrophotometer (FTIR) analysis revealed that Sb ions could not entirely supplant the Sn ions in the SnO2 lattice for a calcining time of less than 0.5 h,even at a calcining temperature of 1000℃.The ATO nanoparticles calcined at 1000℃ for 3.0h possessed the lowest resistivity of 10.18Ωcm.

  20. Argonne National Laboratory (ANL) Progress in Minimizing Effects of LEU conversion on calcination of fission product 99Mo acid waste solution

    International Nuclear Information System (INIS)

    A partnership between Argonne National Laboratory (ANL), MDS Nordion (MDSN), Atomic Energy Canada Limited (AECL) and SGN (France) has addressed the conversion of the MAPLE Reactor 99Mo production process from high-enriched uranium (HEU) targets to low-enriched uranium (LEU) targets. One effect of the conversion would be to increase the amount of solid uranium waste five-fold; we have worked to minimize the effect of the additional waste on the overall production process and, in particular, solid waste storage. Two processes were investigated for the treatment of the uranium-rich acidic waste solution: direct calcination, and oxalate precipitation as a prelude to calcination. Direct calcination generates a dense UO3 solid that should allow a significantly greater amount of uranium in one waste container than is planned for the HEU process, but doing so results in undesirable sputtering. These results suggest that direct calcination could be adapted for use with LEU targets without a large effect on the uranium waste treatment procedures. The oxalate-calcination generates a lower-density granular U3O8 product; sputtering is not significant during calcination of the uranyl oxalate precipitate. A physical means to densify the product would need to be developed to increase the amount of uranium in each waste container. Future work will focus on the specific chemical reactions that occur during the direct and oxalate calcination processes. (author)

  1. Recycled aggregate concrete; an overview

    OpenAIRE

    Sorato, Renan

    2016-01-01

    The aim of this Bachelor’s thesis was to investigate whether recycled materials can be incorporated into the production of concrete without compromising the compressive strength of the concrete produced. In order to shed light on the compressive strength of concrete made from recycled materials, the thesis reviewed studies in which waste materials are utilised as recycled aggregates in the composition of concrete and presented the results of this synthesis and analysis. It was found that som...

  2. Judgment aggregation functions and ultraproducts

    OpenAIRE

    Herzberg, Frederik

    2011-01-01

    The relationship between propositional model theory and social decision making via premise-based procedures is explored. A one-to-one correspondence between ultrafilters on the population set and weakly universal, unanimity-respecting, systematic judgment aggregation functions is established. The proof constructs an ultraproduct of profiles, viewed as propositional structures, with respect to the ultrafilter of decisive coalitions. This representation theorem can be used to prove other proper...

  3. Underground economy and aggregate fluctuations

    OpenAIRE

    Juan Carlos Conesa Roca; Carlos Díaz Moreno; José Enrique Galdón Sánchez

    2001-01-01

    This paper explores the role of underground economic activities as an explanation of differences in registered aggregate fluctuations. In order to do so, we introduce an underground economy sector in an otherwise standard Real Business Cycle model and calibrate it to the USA economy. We find that, at low frequencies, Europe fluctuates more than the USA, while its participation rate is smaller. The existence of underground activities rationalizes the negative relationship between participation...

  4. Credit contagion and aggregate losses

    OpenAIRE

    Giesecke, Kay; Weber, Stefan

    2002-01-01

    Credit contagion refers to the propagation of economic distress from one firm or sovereign government to another. In this paper we model credit contagion phenomena and study the fluctuation of aggregate credit losses on large portfolios of financial positions. The joint dynamics of firms’ credit ratings is modeled by a voter process, which is well-known in the theory of interacting particle systems. We clarify the structure of the equilibrium joint rating distribution using ergodic decomposit...

  5. Aggregating Labels in Crowdsourcing Data

    OpenAIRE

    Priisalu, Maria; Grey, Francois; Segal, Ben

    2015-01-01

    Project Specification Crowdsourcing is gaining popularity in academia with the launch of crowdsourcing platforms such as Crowdcrafting [Lombraña, 2015] and GeoTagX [UNOSAT, 2015]. There have been a number of proposed algorithms for the aggregation of true labels and a confusion matrix from crowdsourced labels for ordinal, nominal and binary labels. The work here consists of an implementation of the Dawid Skene [Dawid 1979] adaptation of the Expectation Maximization algorithm [D...

  6. Protein aggregates in Huntington's disease

    OpenAIRE

    Arrasate, M.; Finkbeiner, S

    2011-01-01

    Huntington's disease (HD) is an incurable neurodegenerative disease characterized by abnormal motor movements, personality changes, and early death. HD is caused by a mutation in the IT-15 gene that expands abnormally the number of CAG nucleotide repeats. As a result, the translated protein huntingtin contains disease-causing expansions of glutamines (polyQ) that make it prone to misfold and aggregate. While the gene and mutations that cause HD are known, the mechanisms underlying HD pathogen...

  7. Intuitionistic fuzzy aggregation and clustering

    CERN Document Server

    Xu, Zeshui

    2012-01-01

    This book offers a systematic introduction to the clustering algorithms for intuitionistic fuzzy values, the latest research results in intuitionistic fuzzy aggregation techniques, the extended results in interval-valued intuitionistic fuzzy environments, and their applications in multi-attribute decision making, such as supply chain management, military system performance evaluation, project management, venture capital, information system selection, building materials classification, and operational plan assessment, etc.

  8. Belt conveyor for recycle aggregate

    OpenAIRE

    Bezrodný, Roman

    2014-01-01

    This bachelor thesis deals with the belt conveyor for the transport of recycled aggregate in an oblique direction. The aim is to find constructional solutions to the belt conveyor for the assigned transport capacity of 95 000 kg per hour, and the assigned axial distance of 49 m and different height of 12 m. The thesis contains a brief description of the belt conveyor and a description of basic constructional components. It also contains a functional calculation of the capacity and forces acco...

  9. Aggregate Uncertainty, Money and Banking

    OpenAIRE

    Hongfei Sun

    2006-01-01

    This paper studies the problem of monitoring the monitor in a model of money and banking with aggregate uncertainty. It shows that when inside money is required as a means of bank loan repayment, a market of inside money is entailed at the repayment stage and generates information-revealing prices that perfectly discipline the bank. The incentive problem of a bank is costlessly overcome simply by involving inside money in repayment. Inside money distinguishes itself from outside money by its ...

  10. Economic Instability and Aggregate Investment

    OpenAIRE

    Robert S. Pindyck; Solimano, Andres

    1993-01-01

    Recent literature suggests that because investment expenditures are irreversible and can be delayed, they may be highly sensitive to uncertainty. The authors briefly summarize the theory, stressing its empirical implications. Then, using cross-section and time-series data for a set of developing and industrial countries, they explore the empirical relevance of irreversibility and uncertainty to aggregate investment. They find that: (a) the volatility of the marginal profitability of capital (...

  11. Parametric characterization of aggregation functions

    Czech Academy of Sciences Publication Activity Database

    Mesiar, Radko; Kolesárová, A.

    2009-01-01

    Roč. 160, č. 6 (2009), s. 816-831. ISSN 0165-0114 R&D Projects: GA ČR GA402/08/0618 Institutional research plan: CEZ:AV0Z10750506 Keywords : Aggregation function * Conjunction measure * Disjunction measure * Global/local parametric characterization * Idempotency measure Subject RIV: BA - General Mathematics Impact factor: 2.138, year: 2009 http://library.utia.cas.cz/separaty/2009/E/mesiar-parametriccharacterizationofaggregationfunctions.pdf

  12. 78 FR 68945 - Aggregation of Positions

    Science.gov (United States)

    2013-11-15

    ... (``1979 Aggregation Policy''), 44 FR 33839, 33843 (June 13, 1979). Note, however, that consistent with the... the ownership criteria of aggregation. \\40\\ See, e.g., 53 FR 13290, 13292 (1988) (proposal). The 1988... approach best resolves those issues while maintaining a bright-line aggregation test? \\41\\ See 77 FR...

  13. Aggregation functions: an approach using copulae

    OpenAIRE

    Marta Cardin; Maddalena Manzi

    2007-01-01

    In this paper we present the extension of the copula approach to aggregation functions. In fact we want to focus on a class of aggregation functions and present them in the multilinear form with marginal copulae. Moreover, we define the joint aggregation density function.

  14. 28 CFR 2.5 - Sentence aggregation.

    Science.gov (United States)

    2010-07-01

    ... 28 Judicial Administration 1 2010-07-01 2010-07-01 false Sentence aggregation. 2.5 Section 2.5 Judicial Administration DEPARTMENT OF JUSTICE PAROLE, RELEASE, SUPERVISION AND RECOMMITMENT OF PRISONERS... aggregation. When multiple sentences are aggregated by the Bureau of Prisons pursuant to 18 U.S.C. 4161...

  15. Aggregated Authentication (AMAC) Using Universal Hash Functions

    Science.gov (United States)

    Znaidi, Wassim; Minier, Marine; Lauradoux, Cédric

    Aggregation is a very important issue to reduce the energy consumption in Wireless Sensors Networks (WSNs). There is currently a lack of cryptographic primitives for authentication of aggregated data. The theoretical background for Aggregated Message Authentication Codes (AMACs) has been proposed by Chan and Castelluccia at ISIT 08.

  16. Aggregation of erythrocytes in burn disease

    OpenAIRE

    Levin, Grigory Y; Egorihina, Marpha N

    2011-01-01

    The manuscript describes experiments designed to examine factors that influence erythrocytes aggregation within the blood of burn patients. Results showed that the rate and degree of erythrocytes aggregation increased significantly in burn patients, and what is especially unfavorable for microcirculation, erythrocytes disaggregation decreased. We show that normalization of blood plasma contents completely restores erythrocytes aggregation and disaggregation of burn patients. The rate and degr...

  17. Network Provisioning Using Multimedia Aggregates

    Directory of Open Access Journals (Sweden)

    Joan Vila-Carbó

    2008-01-01

    Full Text Available Multimedia traffic makes network provisioning a key issue. Optimal provisioning of network resources is crucial for reducing the service cost of multimedia transmission. Multimedia traffic requires not only provisioning bandwidth and buffer resources in the network but also guaranteeing a given maximum end-to-end delay. In this paper we present methods and tools for the optimal dimensioning of networks based on multimedia aggregates. The proposed method minimises the network resources reservations of traffic aggregates providing a bounded delay. The paper also introduces several methods to generate multimedia traffic aggregation using real video traces. The method is evaluated using a network topology based on the European GÉANT network. The results of these simulations allow us to discover the relationship between a required delay and the necessary bandwidth reservation (or the achievable utilisation limit. An interesting conclusion of these scenarios is that, following several recommendations, the network utilisation can reach values of around 80% or higher.

  18. Surface modification of calcined kaolin with toluene diisocyanate based on high energy ball milling

    Energy Technology Data Exchange (ETDEWEB)

    Yuan, Yongbing; Chen, Hongling, E-mail: hlchen@njut.edu.cn; Lin, Jinbin; Ji, Yan

    2013-11-01

    The surface of calcined kaolin particle was modified with toluene diisocyanate (TDI) by using high energy ball milling. The prepared hybrids were characterized by FT-IR, MAS NMR, thermal analysis (TGA-DSC), static water contact angle (CA), apparent viscosity and transmission electron microscopy (TEM). FT-IR and MAS NMR spectra demonstrated that TDI molecules were chemically anchored to kaolin surface after modification. The results of thermal analysis showed that the maximum grafting ratio reached up to 446.61% when the mass ratio of TDI/kaolin was 0.5:1.0, and CA measurements revealed that the resultant hybrids exhibited strong hydrophobicity (148.82°). Apparent viscosity and TEM were employed to examine the dispersion properties of blank and modified kaolin particles in poly (dimenthylsiloxane) matrix. The results illustrated that the dispersion stability depended strongly on the grafting ratio of TDI, neither too low nor too high achieved uniform and stable dispersion, and the favorable grafting ratio was obtained when the mass ratio of TDI/kaolin was 0.2:1.0. Further modification of TDI/kaolin (mass ration of TDI/kaolin, 1.0:1.0) particles with bis(aminopropyl)-terminated-poly(dimethylsiloxane) (APS) was also investigated. TEM evidenced that the dispersion properties of the obtained TDI/APS/kaolin particles were remarkably improved in octamethyl cyclotetrasiloxane compared with the original TDI/kaolin particles.

  19. Grain growth and microstructural evolution of yttrium aluminum garnet nanocrystallites during calcination process

    International Nuclear Information System (INIS)

    An yttrium aluminum garnet (YAG) precursor precipitate was synthesized by urea method using yttria (Y2O3) and aluminum nitrate (Al(NO3)3.9H2O) as raw materials. The fresh wet precipitate was dried by supercritical carbon dioxide (CO2) fluid and the resulting powder was calcined at temperatures from 600 to 1600 oC. Crystallization of YAG was detected at 800 oC, and completed at 900 oC. HRTEM images of the YAG product obtained above 900 oC revealed crystallographically specific oriented attachment along the [1 1 2] direction. Based on the observation of the particle morphology a possible growth mechanism of YAG nanoparticles was presented. The fast increase on the average crystallite size of YAG at temperatures from 900 to 1300 oC is attributed to the crystallographically specific oriented attachment growth process. As the growth process proceeds at higher temperatures, oriented attachment based growth becomes less important because of the increase on particle size, and the self-integration assisted by the Ostwald ripening becomes dominant.

  20. Advanced mineral calciner for regeneration of lime. Final report, March 1995--May 1997

    Energy Technology Data Exchange (ETDEWEB)

    Namazian, M.; Nickeson, R.; Lovas, B.; Miller, G.; Kelly, J.

    1997-12-31

    There are approximately 800 pulp, paper and paperboard mills in the United States. Pulp and paper is the ninth largest industry in US, uses 2.8 quads of energy per year and ranks third among all domestic US industries in the cost of energy consumed. A significant fraction of the energy consumed in pulp and paper plants is needed to recover chemicals that are used in breaking down the wood chips into pulp. In particular, 0.1 quads of energy per year are used to regenerate lime. Furthermore, pulp and paper plant operations generate 9,870 tons of NOx per year. Additionally over two million tons of spent lime are sent to landfills each year. In addition, growth in paper demand and changes in plant processes (e.g., bleaching), as a result of environmental pressures, will continue to drive the need for more lime regeneration capacity. Unless the increased capacity can be delivered productively and inexpensively, the growth in pulp and paper may occur in overseas markets. Furthermore, if new environmental constraints cannot be met at low cost, existing US pulp and paper production capacity may also move off-shore. The advanced mineral calciner (AMC) technology was developed to address this lime regeneration need. Prior to describing the technology, and the program of work that was used to test the concept, conventional lime regeneration systems and their limitations are described.

  1. Strength of Limestone-based Non-calcined Cement and its Properties

    Institute of Scientific and Technical Information of China (English)

    LIN Zongshou; ZHAO Qian

    2009-01-01

    A new type of cement was prepared with ground limestone powder,blastfurnace slag,steel slag and gypsum without calcination.The fraction of ground limestone powder in the cement was as high as 40 wt%-60 wt%without Portland clinker.All of its physical properties can meet the requirements of masonry cement standards.The impact of limestone content on physical properties of the cement and determined its impact on law was investigated.The steel slag can excit the aquation activity of this cement effectively,and the influence of its quantity on the strength of the materials was studied,which shows that the optimum quantity of mixing is 10%.By way of changing the different content of the lime stone by quartzy sample,the law of the compression strength and the PH value was determined,confirming that the lime stone can promote the early aquation of the slag and improve the early strength.The main hydration product of this cement is calcium aluminate hydrate, ettringite and calcium silicate hydrate,as indicated by XRD and SEM analysis.

  2. Optimization Study on the Leaching of High Iron-Bearing Zinc Calcine After Reduction Roasting

    Science.gov (United States)

    Han, Junwei; Liu, Wei; Qin, Wenqing; Zheng, Yongxing; Luo, Honglin

    2016-02-01

    The selective leaching of zinc from high iron-bearing zinc calcine after reduction roasting was optimized by Taguchi experimental design method. The experimental parameters and their ranges were 303 to 343 K (30 to 70 °C) for leaching temperature ( T), 7 to 15 mL/g for liquid/solid ratio ( L/ S), 70 to 150 g/L for H2SO4 concentration ( C), 5 to 25 minutes for time ( t), and 100 to 500 rpm for stirring speed ( R). The results show that the optimum conditions were 303 K (30 °C), 9 mL/g, 110 g/L, 20 minutes, and 400 rpm, respectively. Under these conditions, about 92.81 pct Zn was extracted and more than 86 pct Fe was reported into the leach residue. L/ S and C had significant effects on the extractions of zinc and iron, while t and R had no significant effects, and T had significant effect on iron extraction but negligible effect on zinc extraction. This indicates that diffusion was not a major control step of the leaching process, and the dissolution of iron was controlled by chemical reaction. The interactive effects of parameters were negligible. The leach residue was mainly composed of Fe3O4 and ZnS, and its particle size was very fine.

  3. Sorption of H₃BO₃/B(OH)₄⁻ on calcined LDHs including different divalent metals.

    Science.gov (United States)

    Qiu, Xinhong; Sasaki, Keiko; Osseo-Asare, Kwadwo; Hirajima, Tsuyoshi; Ideta, Keiko; Miyawaki, Jin

    2015-05-01

    LDHs with different divalent metals (Zn-LDH, Mg-LDH and Ca-LDH) have been synthesized and produced calcined LDHs (Zn-CLDH, Mg-CLDH and Ca-CLDH) for borate removal. Based on XRD, SEM, BET, (27)Al NMR, CO2-TPD, and (11)B NMR, detailed characterization of different CLDHs before and after reaction with the boron species was systematically performed. The surface area, basicity and the particle charge of the different CLDHs, which are related to the hydration and regeneration, were markably influenced by the nature of the divalent metals. Transformation of crystal phases and the types of boron species adsorbed by the different CLDHs varied as time changed. The regeneration of Ca-CLDH required the shortest time. However, Ca-LDH decomposed to release Ca(2+) ions, forming ettringite with borate. Zn-CLDH also rapidly transformed into Zn-LDH. During this reconstruction, B(OH)4(-) was intercalated into the interlayer of Zn-LDHs, which is the predominant mechanism of borate removal by Zn-CLDH. Increase in the initial pH caused a competition between borate and OH(-) so that the removal efficiency of borate by Zn-CLDH decreased. For Mg-CLDH, surface complexation and electrostatic attraction were included in the first stage, immobilizing boric acid into Mg(OH)2 and attracting borate as interlayer anionic species into the new forming Mg-LDHs in the second stage. PMID:25618238

  4. Adsorption of methyl orange from aqueous solution onto calcined Lapindo volcanic mud

    International Nuclear Information System (INIS)

    In this study, calcined Lapindo volcanic mud (LVM) was used as an adsorbent to remove an anionic dye, methyl orange (MO), from an aqueous solution by the batch adsorption technique. Various conditions were evaluated, including initial dye concentration, adsorbent dosage, contact time, solution pH, and temperature. The adsorption kinetics and equilibrium isotherms of the LVM were studied using pseudo-first-order and -second-order kinetic equations, as well as the Freundlich and Langmuir models. The experimental data obtained with LVM fits best to the Langmuir isotherm model and exhibited a maximum adsorption capacity (qmax) of 333.3 mg g-1; the data followed the second-order equation. The intraparticle diffusion studies revealed that the adsorption rates were not controlled only by the diffusion step. The thermodynamic parameters, such as the changes in enthalpy, entropy, and Gibbs free energy, showed that the adsorption is endothermic, random and spontaneous at high temperature. The results indicate that LVM adsorbs MO efficiently and could be utilized as a low-cost alternative adsorbent for the removal of anionic dyes in wastewater treatment.

  5. Stabilization of lead and copper contaminated firing range soil using calcined oyster shells and fly ash.

    Science.gov (United States)

    Moon, Deok Hyun; Park, Jae-Woo; Cheong, Kyung Hoon; Hyun, Seunghun; Koutsospyros, Agamemnon; Park, Jeong-Hun; Ok, Yong Sik

    2013-12-01

    A stabilization/solidification treatment scheme was devised to stabilize Pb and Cu contaminated soil from a firing range using renewable waste resources as additives, namely waste oyster shells (WOS) and fly ash (FA). The WOS, serving as the primary stabilizing agent, was pre-treated at a high temperature to activate quicklime from calcite. Class C FA was used as a secondary additive along with the calcined oyster shells (COS). The effectiveness of the treatment was evaluated by means of the toxicity characteristic leaching procedure (TCLP) and the 0.1 M HCl extraction tests following a curing period of 28 days. The combined treatment with 10 wt% COS and 5 wt% FA cause a significant reduction in Pb (>98 %) and Cu (>96 %) leachability which was indicated by the results from both extraction tests (TCLP and 0.1 M HCl). Scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDX) analyses are used to investigate the mechanism responsible for Pb and Cu stabilization. SEM-EDX results indicate that effective Pb and Cu immobilization using the combined COS-FA treatment is most probably associated with ettringite and pozzolanic reaction products. The treatment results suggest that the combined COS-FA treatment is a cost effective method for the stabilization of firing range soil. PMID:23709229

  6. Environmental assessment: Closure of the Waste Calcining Facility (CPP-633), Idaho National Engineering Laboratory

    International Nuclear Information System (INIS)

    The U.S. Department of Energy (DOE) proposes to close the Waste Calcining Facility (WCF). The WCF is a surplus DOE facility located at the Idaho Chemical Processing Plant (ICPP) on the Idaho National Engineering Laboratory (INEL). Six facility components in the WCF have been identified as Resource Conservation and Recovery Ace (RCRA)-units in the INEL RCRA Part A application. The WCF is an interim status facility. Consequently, the proposed WCF closure must comply with Idaho Rules and Standards for Hazardous Waste contained in the Idaho Administrative Procedures Act (IDAPA) Section 16.01.05. These state regulations, in addition to prescribing other requirements, incorporate by reference the federal regulations, found at 40 CFR Part 265, that prescribe the requirements for facilities granted interim status pursuant to the RCRA. The purpose of the proposed action is to reduce the risk of radioactive exposure and release of hazardous constituents and eliminate the need for extensive long-term surveillance and maintenance. DOE has determined that the closure is needed to reduce potential risks to human health and the environment, and to comply with the Idaho Hazardous Waste Management Act (HWMA) requirements

  7. Draft environmental assessment -- Closure of the Waste Calcining Facility (CPP-633), Idaho National Engineering Laboratory

    Energy Technology Data Exchange (ETDEWEB)

    Braun, J.B.; Irving, J.S.; Staley, C.S.; Stanley, N.

    1996-04-01

    The DOE-Idaho Operations Office has prepared an environmental assessment (EA) to analyze the environmental impacts of closing the Waste Calcining Facility (WCF) at the Idaho National Engineering Laboratory (INEL). The purpose of the action is to reduce the risk of radioactive exposure and release of radioactive and hazardous constituents and eliminate the need for extensive long-term surveillance and maintenance. DOE has determined that the closure is needed to reduce these risks to human health and the environment and to comply with Resource Conservation and Recovery Act requirements. The WCF closure project is described in the DOE Programmatic Spent Nuclear Fuel Management and Idaho National Engineering Laboratory Environmental Restoration and Waste Management Programs Final Environmental Impact Statement (Programmatic EIS). DOE determined in the Programmatic EIS Record of Decision (ROD) that certain actions would be implemented and other actions deferred. The EA examined the potential environmental impacts of the proposed action and evaluated reasonable alternatives, including the no action alternative in accordance with the Council on Environmental Quality Regulations. Based on the analysis in the EA, the action will not have a significant effect on the human environment.

  8. Environmental assessment: Closure of the Waste Calcining Facility (CPP-633), Idaho National Engineering Laboratory

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1996-07-01

    The U.S. Department of Energy (DOE) proposes to close the Waste Calcining Facility (WCF). The WCF is a surplus DOE facility located at the Idaho Chemical Processing Plant (ICPP) on the Idaho National Engineering Laboratory (INEL). Six facility components in the WCF have been identified as Resource Conservation and Recovery Ace (RCRA)-units in the INEL RCRA Part A application. The WCF is an interim status facility. Consequently, the proposed WCF closure must comply with Idaho Rules and Standards for Hazardous Waste contained in the Idaho Administrative Procedures Act (IDAPA) Section 16.01.05. These state regulations, in addition to prescribing other requirements, incorporate by reference the federal regulations, found at 40 CFR Part 265, that prescribe the requirements for facilities granted interim status pursuant to the RCRA. The purpose of the proposed action is to reduce the risk of radioactive exposure and release of hazardous constituents and eliminate the need for extensive long-term surveillance and maintenance. DOE has determined that the closure is needed to reduce potential risks to human health and the environment, and to comply with the Idaho Hazardous Waste Management Act (HWMA) requirements.

  9. Chloride adsorption by calcined layered double hydroxides in hardened Portland cement paste

    KAUST Repository

    Yoon, Seyoon

    2014-06-01

    This study investigated the feasibility of using calcined layered double hydroxides (CLDHs) to prevent chloride-induced deterioration in reinforced concrete. CLDHs not only adsorbed chloride ions in aqueous solution with a memory effect but also had a much higher binding capacity than the original layered double hydroxides (LDHs) in the cement matrix. We investigated this adsorption in hardened cement paste in batch cultures to determine adsorption isotherms. The measured and theoretical binding capacities (153 mg g -1 and 257 mg g-1, respectively) of the CLDHs were comparable to the theoretical capacity of Friedel\\'s salt (2 mol mol-1 or 121 mg g-1), which belongs to the LDH family among cementitious phases. We simulated chloride adsorption by CLDHs through the cement matrix using the Fickian model and compared the simulation result to the X-ray fluorescence (XRF) chlorine map. Based on our results, it is proposed that the adsorption process is governed by the chloride transport through the cement matrix; this process differs from that in an aqueous solution. X-ray diffraction (XRD) analysis showed that the CLDH rebuilds the layered structure in a cementitious environment, thereby demonstrating the feasibility of applying CLDHs to the cement and concrete industries. © 2014 Published by Elsevier B.V. All rights reserved.

  10. Electron transfer behavior and water photodecomposition ability of calcined material from a cerium-S-phenylene-O-holmium-O-phenylene-S hybrid copolymer.

    Science.gov (United States)

    Matsui, Hideo; Otsuki, Keigo; Yamada, Hiroyoshi; Kawahara, Tetsuro; Yoshihara, Masakuni

    2006-05-15

    Calcination of a cerium-S-phenylene-O-holmium-O-phenylene-S hybrid copolymer under a vacuum gave cerium oxide-carbon cluster-holmium oxide composite material. The material calcined at 600 degrees C loaded with Pt particles could decompose water to H2 and O2 with a H2/O2 ratio of 2 under visible light irradiation. ESR spectral examinations of the calcined materials revealed the possibility of a two-step electron transfer in the process of CeO2 --> carbon cluster --> Ho2O3 --> Pt with an oxidation site at CeO2 particles and a reduction site at Pt particles. PMID:16313919

  11. Characterization and use of in natura and calcined rice husks for biosorption of heavy metals ions from aqueous effluents

    Directory of Open Access Journals (Sweden)

    M. G. A. Vieira

    2012-09-01

    Full Text Available Heavy metal removal by adsorption using rice husks as a bioadsorbent was evaluated as an alternative for wastewater treatment. Batch equilibrium experiments and kinetic sorption studies were performed using monocomponent solutions of Ni(II, Cd(II, Zn(II, Pb(II and Cu(II in surface samples of in natura(RH and calcined rice husks (RHA. RHA showed higher potential for removing lead and copper. Experimental data for adsorption isotherms of lead and copper were adjusted by Langmuir, Freundlich and Dubinin-Radushkevick (D-R models, being better represented by the Langmuir model. The calcination of RH increased its surface area, improving its adsorption properties. From a morphological analysis obtained by SEM and diffraction patterns (XRD, a longitudinal fibrous and amorphous structure was observed for RH. TGA resultsindicated a total mass loss of around 60% for RH and 24.5% for RHA.

  12. Studies of the Catalytic Activity and Deactivation of Calcined Layered Double Hydroxides in the Reaction of Ethanol with Propylene Oxide

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The reaction of ethanol with propylene oxide over calcined layered double hydroxides(CLDH) was investigated. The results show that CLDH has a good activity and a good selectivity, but the activity and the selectivity of CLDH decrease when CLDH reforms LDH- the so called "memory effect". The influence of the "memory effect" on the CLDH returning to LDH was studied by the hydration reaction. It is shown that the "memory effect" is not complete, and the decreases of the Mg/Al molar ratio of LDH and the crystallite size due to the increase of the hydration reaction time result in the drop of the activity and the selectivity.Keyworcds Ethanol, Propylene oxide, Calcined layered double hydroxide, "Memory effect", Hydration

  13. Effect of the calcining temperature on the porosity of the titanium dioxide powders obtained by Polymeric Precursor Method

    International Nuclear Information System (INIS)

    Ceramics materials obtained by Polymeric Precursor Method exhibit mechanisms of the pore formation and elimination dependents on the decomposition kinetics of the residual organic matter of the polyester. The mechanism of pore elimination seems to occur by disrupting of the wall among the pores because it leads to the consequent pore coalescence and increasing in pore volume, which posses higher pore diameters. In this case, it was observed that the porosity decreasing occurs by pore wall moving after that the residual organic matter is eliminated from the pore inside. The pore diameter associated to the highest volume desorption occurred for the material obtained after calcining at 450°C is approximately 1,7 nm, what seems to be related to the amorphous carbon accumulated inside the pores, once that the pore volume decreases more effectively for the material obtained by calcining at 550°C, making the maximum volume situates at 2,0 nm. (author)

  14. [AGGREGATION OF METABOLICALLY DEPLETED HUMAN ERYTHROCYTES].

    Science.gov (United States)

    Sheremet'ev, Yu A; Popovicheva, A N; Rogozin, M M; Levin, G Ya

    2016-01-01

    An aggregation of erythrocytes in autologous plasma after blood storage for 14 days at 4 °C was studied using photometry and light microscopy. The decrease of ATP content, the formation of echinocytes and spheroechinocytes, the decrease of rouleaux form of erythrocyte aggregation were observed during the storage. On the other hand the aggregates of echinocytes were formed in the stored blood. The addition of plasma from the fresh blood didn't restore the normal discocytic shape and aggregation of erythrocytes in the stored blood. The possible mechanisms of erythrocytes and echinocytes aggregation are discussed. PMID:27220249

  15. [Lysophosphatidic acid and human erythrocyte aggregation].

    Science.gov (United States)

    Sheremet'ev, Iu A; Popovicheva, A N; Levin, G Ia

    2014-01-01

    The effects of lysophosphatidic acid on the morphology and aggregation of human erythrocytes has been studied. Morphology of erythrocytes and their aggregates were studied by light microscopy. It has been shown that lysophosphatidic acid changes the shape of red blood cells: diskocyte become echinocytes. Aggregation of red blood cells (rouleaux) was significantly reduced in autoplasma. At the same time there is a strong aggregation of echinocytes. This was accompanied by the formation of microvesicles. Adding normal plasma to echinocytes restores shape and aggregation of red blood cells consisting of "rouleaux". A possible mechanism of action of lysophosphatidic acid on erythrocytes is discussed. PMID:25509147

  16. Electrochemical characterization for lithium vanadium phosphate with different calcination temperatures prepared by the sol–gel method

    International Nuclear Information System (INIS)

    Li3V2(PO4)3/C (LVP/C) composite materials were synthesized via a sol–gel method with oxalic acid as the chelating agent and polyethylene glycol (PEG) as the supplementary carbon source. The oxalic acid and PEG serve as double carbon sources. This study focused on the effect of different calcination temperatures on the electrochemical properties of Li3V2(PO4)3. The diffraction peaks for all of the samples are well indexed to monoclinic Li3V2(PO4)3 with a P21/n space group. The TGA data indicate that the residual carbon content of LVP/C-700 is the highest (i.e., 2.31 wt.%), and as the calcination temperature increased, the residual carbon content of the material gradually decreased. SEM and TEM analyses indicated that the LVP particles that were calcined at 700 °C exhibit a uniform particle size distribution and the carbon coating exhibited a complete and orderly moderate thickness. The LVP/C-700 material exhibits the best electrochemical performance in the voltage range of 3.0 to 4.3 V and 0.1 C where the initial discharge capacity can reach 128.98 mAh g− 1. Even after 200 cycles, the discharge capacity was 119.31 mAh g− 1, and the capacity retention rate was 92.49%. - Highlights: • Li3V2(PO4)3/C composite materials have been synthesized via a sol–gel method with double carbon sources. • The different calcination temperatures affect the grain growth and crystallinity of the Li3V2(PO4)3/C materials. • The LVP/C-700 material exhibites the largest lithium ion diffusivity and electronic conductivity

  17. Tailoring the Microstructure of a Solid Oxide Fuel Cell Anode Support by Calcination and Milling of YSZ

    Science.gov (United States)

    Hanifi, Amir Reza; Laguna-Bercero, Miguel A.; Sandhu, Navjot Kaur; Etsell, Thomas H.; Sarkar, Partha

    2016-06-01

    In this study, the effects of calcination and milling of 8YSZ (8 mol% yttria stabilized zirconia) used in the nickel-YSZ anode on the performance of anode supported tubular fuel cells were investigated. For this purpose, two different types of cells were prepared based on a Ni-YSZ/YSZ/Nd2NiO4+δ-YSZ configuration. For the anode preparation, a suspension was prepared by mixing NiO and YSZ in a ratio of 65:35 wt% (Ni:YSZ 50:50 vol.%) with 30 vol.% graphite as the pore former. As received Tosoh YSZ or its calcined form (heated at 1500 °C for 3 hours) was used in the anode support as the YSZ source. Electrochemical results showed that optimization of the fuel electrode microstructure is essential for the optimal distribution of gas within the support of the cell, especially under electrolysis operation where the performance for an optimized cell (calcined YSZ) was enhanced by a factor of two. In comparison with a standard cell (containing as received YSZ), at 1.5 V and 800 °C the measured current density was ‑1380 mA cm‑2 and ‑690 mA cm‑2 for the cells containing calcined and as received YSZ, respectively. The present study suggests that the anode porosity for improved cell performance under SOEC is more critical than SOFC mode due to more complex gas diffusion under electrolysis mode where large amount of steam needs to be transfered into the cell.

  18. Non-enzymatic amperometric detection of hydrogen peroxide using grass-like copper oxide nanostructures calcined in nitrogen atmosphere

    International Nuclear Information System (INIS)

    Highlights: •Unique grass-like CuO nanostructures prepared by simple hydrothermal reactions. •The influence of calcination in N2 atmosphere on CuO nanostructures was discussed. •Study of processing-structure-property relationship of different CuO samples. •As-prepared sensors exhibited excellent electrochemical catalytic performance. •As-synthesized sensors show great application potential of detecting H2O2. -- Abstract: In this research, grass-like CuO nanostructure was synthesized via a simple hydrothermal reaction at 100 °C for 6 h without using any surfactant. The as-prepared sample was further calcined at 500 °C for 1 h in nitrogen atmosphere for comparison. The surface morphology, crystal structure and chemical composition of the products were investigated by scanning electron microscopy (SEM), powder X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and room temperature photoluminescence spectroscopy (PL). The as-synthesized samples were also characterized systematically by electrochemical methods including cyclic voltammetry (CV), amperometric detection (i-t) and electrochemical impedance spectroscopy (EIS). It was found that the sample prepared after calcination in a nitrogen atmosphere exhibited better electrochemical catalytic performance for the determination of H2O2. In addition, high sensitivity (119.35 μA/mM) and fast amperometric response (< 3 s) were achieved; mainly due to the large specific surface area of the grass-like morphology, efficient electron charge transfer property resulting from the increased crystallinity after calcination, as well as more available and active absorption sites induced by surface defects and the CuO/Cu2O heterostructure, thus making it one of the promising candidates for the efficient and sensitive non-enzymatic amperometric detection of H2O2

  19. Structure and luminescence behaviour of as-synthesized, calcined, and restored MgAlEu-LDH with high crystallinity.

    Science.gov (United States)

    Zhao, Yushuang; Li, Ji-Guang; Fang, Fang; Chu, Nankai; Ma, Hui; Yang, Xiaojing

    2012-10-21

    Highly crystalline Eu(3+)-incorporated MgAl layered double hydroxides (LDHs) were synthesized by the homogeneous precipitation method. For the crystals as-prepared, after their calcination from 200-1000 °C, and, further, after restoration in a Na(2)CO(3) solution, the structural and luminescent changes were investigated for the first time. Eu(3+) ions with a coordination number of, probably, 8, were incorporated into the hydrotalcite layer, which led to a basal spacing (d(basal)) increase, microstrain formation, and crystalline morphology imperfections, while retaining the original lattice symmetry, R3[combining macron]m. In the deconstruction process due to calcination, the Eu(3+) ions restrained the formation of the spinel phase from the layered double oxide (LDO), but did not significantly change the memory effect, by which LDOs can convert to LDHs during the hydration process. For the reversible phase transformation between LDH and LDO, the morphology observation revealed that, in addition to the formation of pores on the surface, nano-slabs were formed, especially for the restored crystals. A layered phase with a d(basal) of 5.8 Å, due to bridging bidentate carbonates with the hydrotalcite layer, was formed in the calcination process at low temperature (300 °C) before the formation of LDO, but could not be restored to a large spacing. Typical (5)D(0) → (7)F(J) (J = 0-4) transitions of Eu(3+) at 579, 593, 615, 653, and 698 nm were observed in the photoluminescence spectra and the intensity of the dominating 615 nm band decreased with the LDH deconstruction and the formation of free water, and then increased with the formation of LDOs in the calcination process, and vice versa in the reconstruction process. The Eu(3+) ions had a probable 9- or 10-coordination mode in addition to the probable 8-coordination mode as the spinel phase appeared. PMID:22930336

  20. Aggregation of Diesel Contaminated Soil for Bioremediation

    Institute of Scientific and Technical Information of China (English)

    Yu Ying; Shi Xiu-hong; Li Song; Xu Jing-gang

    2014-01-01

    Diesel contaminated soil (DCS) contained a large amount of the hydrocarbons and salt which was dominated by soluble sodium chloride. Aggregation process which made the desired aggregate size distribution could speed up the degradation rate of the hydrocarbons since the aggregated DCS had better physical characteristics than the non-aggregated material. Artificial aggregation increased pores >30 µm by approximately 5% and reduced pores <1 µm by 5%, but did not change the percentage of the pores between 1 and 30 µm. The saturated hydraulic conductivity of non-aggregated DCS was 5×10-6 m• s-l, but it increased to 1×10-5 m• s-l after aggregation. The compression index of the non-aggregated DCS was 0.0186; however, the artificial aggregates with and without lime were 0.031 and 0.028, respectively. DCS could be piled 0.2 m deep without artificial aggregation; however, it could be applied 0.28 m deep when artificial aggregates were formed without limiting O2 transport.

  1. Bouncing Behavior of Microscopic Dust Aggregates

    CERN Document Server

    Seizinger, Alexander

    2013-01-01

    Context: Bouncing collisions of dust aggregates within the protoplanetary may have a significant impact on the growth process of planetesimals. Yet, the conditions that result in bouncing are not very well understood. Existing simulations studying the bouncing behavior used aggregates with an artificial, very regular internal structure. Aims: Here, we study the bouncing behavior of sub-mm dust aggregates that are constructed applying different sample preparation methods. We analyze how the internal structure of the aggregate alters the collisional outcome and determine the influence of aggregate size, porosity, collision velocity, and impact parameter. Methods: We use molecular dynamics simulations where the individual aggregates are treated as spheres that are made up of several hundred thousand individual monomers. The simulations are run on GPUs. Results: Statistical bulk properties and thus bouncing behavior of sub-mm dust aggregates depend heavily on the preparation method. In particular, there is no uni...

  2. An exact approach for aggregated formulations

    DEFF Research Database (Denmark)

    Gamst, Mette; Spoorendonk, Simon

    Aggregating formulations is a powerful approach for transforming problems into taking more tractable forms. Aggregated formulations can, though, have drawbacks: some information may get lost in the aggregation and { put in a branch-and-bound context { branching may become very di_cult and even...... mathematical formulation and the aggregated formulation. The method allows usage of relaxed aggregated formulations and enables branching on both aggregated and disaggregated variables. Also, the method guarantees an LP bound at least as good as those for the disaggregated and aggregated formulations. The...... paper includes general considerations on types of problems for which the method is of particular interest. Furthermore, we prove the correctness of the procedure and consider how to include extensions such as cutting planes and advanced branching strategies....

  3. Microwave extinction characteristics of nanoparticle aggregates

    Science.gov (United States)

    Wu, Y. P.; Cheng, J. X.; Liu, X. X.; Wang, H. X.; Zhao, F. T.; Wen, W. W.

    2016-07-01

    Structure of nanoparticle aggregates plays an important role in microwave extinction capacity. The diffusion-limited aggregation model (DLA) for fractal growth is utilized to explore the possible structures of nanoparticle aggregates by computer simulation. Based on the discrete dipole approximation (DDA) method, the microwave extinction performance by different nano-carborundum aggregates is numerically analyzed. The effects of the particle quantity, original diameter, fractal structure, as well as orientation on microwave extinction are investigated, and also the extinction characteristics of aggregates are compared with the spherical nanoparticle in the same volume. Numerical results give out that proper aggregation of nanoparticle is beneficial to microwave extinction capacity, and the microwave extinction cross section by aggregated granules is better than that of the spherical solid one in the same volume.

  4. Calcined Eggshell Waste for Mitigating Soil Antibiotic-Resistant Bacteria/Antibiotic Resistance Gene Dissemination and Accumulation in Bell Pepper.

    Science.gov (United States)

    Ye, Mao; Sun, Mingming; Feng, Yanfang; Li, Xu; Schwab, Arthur P; Wan, Jinzhong; Liu, Manqiang; Tian, Da; Liu, Kuan; Wu, Jun; Jiang, Xin

    2016-07-13

    The combined accumulation of antibiotics, heavy metals, antibiotic-resistant bacteria (ARB)/antibiotic resistance genes (ARGs) in vegetables has become a new threat to human health. This is the first study to investigate the feasibility of calcined eggshells modified by aluminum sulfate as novel agricultural wastes to impede mixed contaminants from transferring to bell pepper (Capsicum annuum L.). In this work, calcined eggshell amendment mitigated mixed pollutant accumulation in bell pepper significantly, enhanced the dissipation of soil tetracycline, sulfadiazine, roxithromycin, and chloramphenicol, decreased the water-soluble fractions of antibiotics, and declined the diversity of ARB/ARGs inside the vegetable. Moreover, quantitative polymerase chain reaction analysis detected that ARG levels in the bell pepper fruits significantly decreased to 10(-10) copies/16S copies, indicating limited risk of ARGs transferring along the food chain. Furthermore, the restoration of soil microbial biological function suggests that calcined eggshell is an environmentally friendly amendment to control the dissemination of soil ARB/ARGs in the soil-vegetable system. PMID:27333280

  5. Structure Analysis and Fluorescence of Mg-Al-Tb Ternary Layered Double Hydroxides and Their Calcined Products

    Science.gov (United States)

    Chen, Junfei; Lei, Zhigao; Wang, Anqi; Liu, Jie; Wu, Xiuling; Chang, Tianci; Zhang, Yang; Li, Muqing

    2015-02-01

    Layered double hydroxides (LDHs) doped with Tb3+ ions in the brucite-like layers were prepared successfully by the co-precipitation method. The structure and fluorescence properties of Mg-Al-Tb ternary LDHs and their products calcined at different temperatures were studied for the first time. X-ray diffraction patterns indicated that as-synthesized LDH samples maintained a hexagonal crystal structure, and Tb(OH)3 was detected as Tb3+ dopant content increasing to 5 at.%. In the fluorescent spectra, the green emission intensity arising from 5D4 → 7F5 transition became stronger with the increasing ratio of Tb3+ dopant. When the annealing temperature rose above 500°C, the layer structure collapsed and phases of MgO and MgAl2O4 formed. Meanwhile, compared with MgAlTb-LDHs, the Tb-doped calcined LDHs (CLDHs) showed stronger luminescent intensity of 5D4 → 7F5 transition. These results revealed that the calcined Mg-Al-Tb ternary LDHs may become a series of novel materials with potential applications in fluorescent devices.

  6. 均质铝矾土煅烧技术的研究%Study on calcining technology for homogeneous bauxite

    Institute of Scientific and Technical Information of China (English)

    谭莹

    2011-01-01

    A simulation experiment study is carried out for homogenous bauxite in tunnel kiln. The ex- periment result shows that the optimal calcining schedule for homogenous bauxite is 1 550℃, 5h. Here the bulk density reaches 3.45g.cm^-3 and the internal microstructure of the bauxite reaches optimal state. Meanwhile the quality index of the specimen is better than that of calcined bauxite QA1-88 obviously. Key words: Homogeneous bauxite ; Calcining temperature ; Holding time ; Quality index%在隧道窑中对均质铝矾土进行了模拟实验研究,结果表明:均质铝矾土的最佳煅烧制度为1550℃、5h,体积密度可达到3.45g·cm^-3,且铝矾土内部微观结构达到最佳状态。同时样品的质量指标明显优于优质铝矾土熟料QA1—88指标。

  7. Mesoporous Titania Powders: The Role of Precursors, Ligand Addition and Calcination Rate on Their Morphology, Crystalline Structure and Photocatalytic Activity

    Directory of Open Access Journals (Sweden)

    Elisabetta Masolo

    2014-07-01

    Full Text Available We evaluate the influence of the use of different titania precursors, calcination rate, and ligand addition on the morphology, texture and phase content of synthesized mesoporous titania samples, parameters which, in turn, can play a key role in titania photocatalytic performances. The powders, obtained through the evaporation-induced self-assembly method, are characterized by means of ex situ X-Ray Powder Diffraction (XRPD measurements, N2 physisorption isotherms and transmission electron microscopy. The precursors are selected basing on two different approaches: the acid-base pair, using TiCl4 and Ti(OBu4, and a more classic route with Ti(OiPr4 and HCl. For both precursors, different specimens were prepared by resorting to different calcination rates and with and without the addition of acetylacetone, that creates coordinated species with lower hydrolysis rates, and with different calcination rates. Each sample was employed as photoanode and tested in the water splitting reaction by recording I-V curves and comparing the results with commercial P25 powders. The complex data framework suggests that a narrow pore size distribution, due to the use of acetylacetone, plays a major role in the photoactivity, leading to a current density value higher than that of P25.

  8. Sulfation of CaO particles in a carbonation/calcination loop to capture CO{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Grasa, G.S.; Alonso, M.; Abanades, J.C. [CSIC, Zaragoza (Spain)

    2008-03-15

    CaO is being proposed as a regenerable sorbent of CO{sub 2} via a carbonation/calcination loop. It is well known that natural sorbents lose their capacity to capture CO{sub 2} with the number of cycles due to textural degradation. In coal combustion systems, reaction with the SO{sub 2} present in flue gases also causes sorbent deactivation. This work investigates the effect of partial sorbent sulfation on the amount of CaO used in systems where both carbonation and sulfation reactions are competing. We have found that SO{sub 2} reacts with the deactivated CaO resulting from repetitive calcination/carbonation reactions. Therefore, the deactivation of CaO as a result of the presence of SO{sub 2} is lower than one would expect if one assumes that SO{sub 2} reacts only with active CaO. This work shows that changes in the texture of the sorbent due to repetitive carbonation/calcination cycles tend to increase the sulfation capacity of the sorbents tested. This suggests that the purge of deactivated CaO obtained from a CO{sub 2} capture loop could be a more effective sorbent of SO{sub 2} than fresh CaO.

  9. SMALL-SCALE TESTING OF PLUTONIUM (IV) OXALATE PRECIPITATION AND CALCINATION TO PLUTONIUM OXIDE TO SUPPORT THE MOX FEED MISSION

    Energy Technology Data Exchange (ETDEWEB)

    Crowder, M.; Pierce, R.; Scogin, J.; Daniel, G.; King, W.

    2012-06-25

    The H-Canyon facility will be used to dissolve Pu metal for subsequent purification and conversion to plutonium dioxide (PuO{sub 2}) using Phase II of HB-Line. To support the new mission, SRNL conducted a series of experiments to produce calcined plutonium (Pu) oxide and measure the physical properties and water adsorption of that material. This data will help define the process operating conditions and material handling steps for HB-Line. An anion exchange column experiment produced 1.4 L of a purified 52.6 g/L Pu solution. Over the next nine weeks, seven Pu(IV) oxalate precipitations were performed using the same stock Pu solution, with precipitator feed acidities ranging from 0.77 M to 3.0 M nitric acid and digestion times ranging from 5 to 30 minutes. Analysis of precipitator filtrate solutions showed Pu losses below 1% for all precipitations. The four larger precipitation batches matched the target oxalic acid addition time of 44 minutes within 4 minutes. The three smaller precipitation batches focused on evaluation of digestion time and the oxalic acid addition step ranged from 25-34 minutes because of pump limitations in the low flow range. Following the precipitations, 22 calcinations were performed in the range of 610-690 C, with the largest number of samples calcined at either 650 or 635 C. Characterization of the resulting PuO{sub 2} batches showed specific surface areas in the range of 5-14 m{sup 2}/g, with 16 of the 22 samples in the range of 5-10 m2/g. For samples analyzed with typical handling (exposed to ambient air for 15-45 minutes with relative humidities of 20-55%), the moisture content as measured by Mass Spectrometry ranged from 0.15 to 0.45 wt % and the total mass loss at 1000 C, as measured by TGA, ranged from 0.21 to 0.58 wt %. For the samples calcined between 635 and 650 C, the moisture content without extended exposure ranged from 0.20 to 0.38 wt %, and the TGA mass loss ranged from 0.26 to 0.46 wt %. Of these latter samples, the samples

  10. Oxidative desulfurization of benzothiophene and thiophene with WOx/ZrO2 catalysts: Effect of calcination temperature of catalysts

    International Nuclear Information System (INIS)

    Highlights: ► Oxidative desulfurization was studied with WOx/ZrO2 calcined at different temp. ► The importance of the phases of zirconia and tungsten oxide was suggested. ► The catalyst was analyzed thoroughly with Raman and XRD techniques. ► The importance of electron density on S was confirmed with the kinetics of oxidation. - Abstract: Oxidative desulfurization (ODS) of model fuel containing benzothiophene (BT) or thiophene (Th) has been carried out with WOx/ZrO2 catalyst, which was calcined at various temperatures. Based on the conversion of BT in the model fuel, it can be shown that the optimum calcination temperature of WOx/ZrO2 catalyst is around 700 °C. The most active catalyst is composed of tetragonal zirconia (ZrO2) with well dispersed polyoxotungstate species and it is necessary to minimize the contents of the crystalline WO3 and monoclinic ZrO2 for a high BT conversion. The oxidation rate was interpreted with the first-order kinetics, and it demonstrated the importance of electron density since the kinetic constant for BT was higher than that for Th even though the BT is larger than Th in size. A WOx/ZrO2 catalyst, treated suitably, can be used as a reusable active catalyst in the ODS.

  11. Credit, Money, and Aggregate Demand

    OpenAIRE

    Bernanke, Ben S.; Alan S. Blinder

    1988-01-01

    Standard models of aggregate demand treat money and credit asymmetrically; money is given a special status, while loans, bonds, and other debt instruments are lumped together in a "bond market" and suppressed by Walras' Law. This makes bank liabilities central to the monetary transmission mechanism, while giving no role to bank assets. We show how to modify a textbook IS-UI model so as to permit a more balanced treatment. As in Tobin (1969) and Brunner-Meltzer (1972), the key assumption is th...

  12. Strategy-proof Preference Aggregation

    OpenAIRE

    Bossert, Walter; Sprumont, Yves

    2012-01-01

    An aggregation rule maps each profile of individual strict preference orderings over a set of alternatives into a social ordering over that set. We call such a rule strategyproof if misreporting one’s preference never produces a social ordering that is strictly between the original ordering and one’s own preference. After describing a few examples of manipulable rules, we study in some detail three classes of strategy-proof rules: (i) rules based on a monotonic alteration of the majority rela...

  13. Inhomogeneous diffusion-limited aggregation

    Science.gov (United States)

    Selinger, Robin Blumberg; Nittmann, Johann; Stanley, H. E.

    1989-01-01

    It is demonstrated here that inhomogeneous diffusion-limited aggregation (DLA) model can be used to simulate viscous fingering in a medium with inhomogeneous permeability and homogeneous porosity. The medium consists of a pipe-pore square-lattice network in which all pores have equal volume and the pipes have negligible volume. It is shown that fluctuations in a DLA-based growth process may be tuned by noise reduction, and that fluctuations in the velocity of the moving interface are multiplicative in form.

  14. PERCOLATION OF RANDOM CYLINDER AGGREGATES

    Directory of Open Access Journals (Sweden)

    Dominique Jeulin

    2011-05-01

    Full Text Available The percolation threshold ρc of Boolean models of cylinders with their axis parallel to a given direction is studied by means of simulations. An efficient method of construction of percolating connected components was developed, and is applied to one or two scales Boolean model, in order to simulate the presence of aggregates. The invariance of the percolation threshold with respect to affine transformations in the common direction of the axis of cylinders is approximately satisfied on simulations. The prediction of the model (ρc close to 0.16 is consistent with experimental measurements on plasma spray coatings, which motivated this study.

  15. Chloride adsorption by calcined layered double hydroxides in hardened Portland cement paste

    Energy Technology Data Exchange (ETDEWEB)

    Yoon, Seyoon [School of Engineering, Kings College, University of Aberdeen, Aberdeen AB24 3UE (United Kingdom); Moon, Juhyuk, E-mail: juhyuk.moon@stonybrook.edu [Civil Engineering Program, Department of Mechanical Engineering, State University of New York at Stony Brook, New York 11794 (United States); Bae, Sungchul [Department of Civil and Environmental Engineering, University of California, Berkeley, CA 94720 (United States); Duan, Xiaonan [Department of Materials Science and Engineering, Cornell University, Ithaca, NY 14853 (United States); Giannelis, Emmanuel P. [Department of Materials Science and Engineering, Cornell University, Ithaca, NY 14853 (United States); Center for Refining and Petrochemicals, The Research Institute, King Fahd University of Petroleum and Minerals, Dhahran 31261 (Saudi Arabia); Monteiro, Paulo M. [Department of Civil and Environmental Engineering, University of California, Berkeley, CA 94720 (United States)

    2014-06-01

    This study investigated the feasibility of using calcined layered double hydroxides (CLDHs) to prevent chloride-induced deterioration in reinforced concrete. CLDHs not only adsorbed chloride ions in aqueous solution with a memory effect but also had a much higher binding capacity than the original layered double hydroxides (LDHs) in the cement matrix. We investigated this adsorption in hardened cement paste in batch cultures to determine adsorption isotherms. The measured and theoretical binding capacities (153 mg g{sup −1} and 257 mg g{sup −1}, respectively) of the CLDHs were comparable to the theoretical capacity of Friedel's salt (2 mol mol{sup −1} or 121 mg g{sup −1}), which belongs to the LDH family among cementitious phases. We simulated chloride adsorption by CLDHs through the cement matrix using the Fickian model and compared the simulation result to the X-ray fluorescence (XRF) chlorine map. Based on our results, it is proposed that the adsorption process is governed by the chloride transport through the cement matrix; this process differs from that in an aqueous solution. X-ray diffraction (XRD) analysis showed that the CLDH rebuilds the layered structure in a cementitious environment, thereby demonstrating the feasibility of applying CLDHs to the cement and concrete industries. - Highlights: • We examine the adsorption equilibrium and kinetics of CLDH in the hydrated cement. • CLDH capacity to bind chloride ions in the hydrated cement paste is determined. • We model chloride adsorption by CLDH through the cement matrix. • CLDH reforms the layered structure with ion adsorption in the cement matrix.

  16. Chloride adsorption by calcined layered double hydroxides in hardened Portland cement paste

    International Nuclear Information System (INIS)

    This study investigated the feasibility of using calcined layered double hydroxides (CLDHs) to prevent chloride-induced deterioration in reinforced concrete. CLDHs not only adsorbed chloride ions in aqueous solution with a memory effect but also had a much higher binding capacity than the original layered double hydroxides (LDHs) in the cement matrix. We investigated this adsorption in hardened cement paste in batch cultures to determine adsorption isotherms. The measured and theoretical binding capacities (153 mg g−1 and 257 mg g−1, respectively) of the CLDHs were comparable to the theoretical capacity of Friedel's salt (2 mol mol−1 or 121 mg g−1), which belongs to the LDH family among cementitious phases. We simulated chloride adsorption by CLDHs through the cement matrix using the Fickian model and compared the simulation result to the X-ray fluorescence (XRF) chlorine map. Based on our results, it is proposed that the adsorption process is governed by the chloride transport through the cement matrix; this process differs from that in an aqueous solution. X-ray diffraction (XRD) analysis showed that the CLDH rebuilds the layered structure in a cementitious environment, thereby demonstrating the feasibility of applying CLDHs to the cement and concrete industries. - Highlights: • We examine the adsorption equilibrium and kinetics of CLDH in the hydrated cement. • CLDH capacity to bind chloride ions in the hydrated cement paste is determined. • We model chloride adsorption by CLDH through the cement matrix. • CLDH reforms the layered structure with ion adsorption in the cement matrix

  17. Mechanism of the sulphation of calcined limestone particles in combustion gases

    Energy Technology Data Exchange (ETDEWEB)

    Dennis, J.S.; Hayhurst, A.N. (Cambridge Univ. (GB). Dept. of Chemical Engineering)

    1990-01-01

    The reaction between SO{sub 2} and CaO, usually from calcined limestone, has been studied in an electrically heated fluidised bed in the presence of varying amounts (including zero) of O{sub 2}. Measurements of the initial rate of uptake of SO{sub 2} were made for small batches of CaO injected into silica sand fluidised by, for example, N{sub 2} + SO{sub 2} + O{sub 2}. The initial rate is found to be independent of the concentration of O{sub 2}. Although O{sub 2} has no effect on the initial rate of sulphation, it can accelerate sulphation of CaO by SO{sub 2} soon after a layer of CaSO{sub 4} has been formed. Ultimate sulphur uptakes are decreased by an increase in the concentration of O{sub 2}, as well as by a decrease in the concentration of SO{sub 2}. In addition, this final uptake of SO{sub 2} shows a maximum at around 1023 K. Below 923 K sulphur absorption is low, because of the low diffusivity of SO{sub 2} through the product CaSO{sub 4}. Above 923 K the overall conversion of a CaO particle to CaSO{sub 4} is limited by pores blocking at their entrances with product. The role of O{sub 2} is not totally clear, but it does appear to affect the crystal size or the number of cracks in the layer of CaSO{sub 4} produced. (author).

  18. Behavior of radioactive iodine and technetium in the spray calcination of high-level waste

    International Nuclear Information System (INIS)

    The Remote Laboratory-Scale Waste Treatment Facility (RLSWTF) was designed and built as a part of the High-Level Waste Immobilization Program (now the High-Level Waste Process Development Program) at the Pacific Northwest Laboratory. In this facility, which is installed in a radiochemical cell, small volumes of radioactive liquid wastes can be solidified, the process off gas can be analyzed, and the methods for decontaminating this off gas can be tested. Initial operations were completed with nonradioactive, simulated waste solutions (Knox, Siemens and Berger 1981). The first radioactive operations in this facility were performed with a simulated, commercial waste composition containing tracer levels of 99Tc and 131I. This report describes the facility and test operations and presents the results of the behavior of 131I and 99Tc during solidification of radioactive liquid wastes. During the spray calcination of commercial high-level liquid waste spiked with 99Tc and 131I, there was a 0.3 wt% loss of particulates, a 0.15 wt% loss of 99Tc and a 31 wt% loss of 131I past the sintered-metal filters. These filters and a venturi scrubber were very efficient in removing particulates and 99Tc from the off-gas stream. Liquid scrubbers were not efficient in removing 131I, as 25% of the total lost went to the building off-gas system. Therefore, solid adsorbents will be needed to remove iodine. For all future RLSWTF operations where iodine is present, a silver zeolite adsorber will be used

  19. The Influence of Calcined Clay Pozzolan, Low-Cao Steel Slag and Granite Dust On the Alkali-Silica Reaction in Concrete

    Directory of Open Access Journals (Sweden)

    James Sarfo-Ansah

    2015-08-01

    Full Text Available The influence of low CaO steel slag, calcined clay and granite dust on the alkali-silica reaction was investigated over a period of 35 days under accelerated curing conditions. The mineral admixtures were used to replace varying portions of high alkali Portland limestone cement up to an admixture content of 25% in order to study their effect on the alkali-silica reaction (ASR. Portland limestone cement used for the study had a total Na2Oeq of 4.32. XRD analysis of hydrated mortar bar samples confirmed the formation of an expansive sodium silica gel in the reference Portland cement mortar bar as the agent responsible for ASR. Stable calcium silicates were formed in the mortar bars containing calcined clay in increasing quantities whilst the presence of the sodium silicate gel decreased.The occurrence of these stable silicates in hydrated samples containing steel slag and granite dust was however minimal, compared to calcined clay cement mortars. The highest expansion was recorded for granite dust mortar bars, reaching a maximum of 25.98% at 35 days. Mortar-bar expansion decreased as calcined clay content in the cement increased;mortar bars with 25% calcined clay were the least expansive recording expansion less than 0.1% at all test ages. Whilst the expansion was reduced by between 42.5% and 107.8% at 14 days with increasing calcined clay content, expansion rather increased between 36.8% and 169.5% at 14 days with increasing granite dust content.Steel slag mortar bars experienced reduction in 14 days expansion between 14.3% - 46.2%.The study confirms that steel slag and calcined clay pozzolan have greater influence on ASR in mortar bars than granite dust and shows that calcined clay and low CaO steel slag could be considered as remedial admixtures for ASR at replacement levels of 25% and 15% respectively.

  20. Catalyst used in 1,2-epoxyalkane preparation is obtained by heating tetraalkyl ammonium salts, tetraalkyl siloxanes and amines, calcining and treating with a tetraalkoxy compound

    DEFF Research Database (Denmark)

    2001-01-01

    NOVELTY - The catalyst, used in 1,2-epoxyalkane preparation, is obtained by heat treating an aqueous composition comprising tetraalkyl ammonium salts, tetraalkyl siloxanes and amines, removing the template by calcining and treating with a tetraalkoxy compound......NOVELTY - The catalyst, used in 1,2-epoxyalkane preparation, is obtained by heat treating an aqueous composition comprising tetraalkyl ammonium salts, tetraalkyl siloxanes and amines, removing the template by calcining and treating with a tetraalkoxy compound...

  1. Utilization Possibility of Natural Aggregate Resources in Central Town of Tokat as Concrete Aggregate

    Directory of Open Access Journals (Sweden)

    S. I. Tutmaz

    2010-01-01

    Full Text Available In this study, aggregates of three quarries sampled from Tokat Province were tested to evaluate their suitability for concrete production. The aggregates were supplied from Yesilirmak River, and largely used in agricultural structures constructed in Tokat. Standard aggregate tests approved by Turkish Standards Institute were carried out to analyze the samples. Granulation, unit weight, specific weight, water absorption rate, resistance to frost, resistance against abrasion, ratio of fine materials, organic material contents and, mineralogical analysis of aggregates sampled from aggregate quarries were determined. Pressure resistance tests were conducted on concrete prepared by the aggregates. The results indicated that the aggregate granulation distribution of aggregate quarries evaluated was not suitable however other parameters determined were appropriate for concrete production. The resultant concrete had sufficient pressure resistance. The possible solutions to improve the improper characteristics of aggregates used in concrete were also determined and introduced with this study.

  2. Protein aggregates in Huntington's disease.

    Science.gov (United States)

    Arrasate, Montserrat; Finkbeiner, Steven

    2012-11-01

    Huntington's disease (HD) is an incurable neurodegenerative disease characterized by abnormal motor movements, personality changes, and early death. HD is caused by a mutation in the IT-15 gene that expands abnormally the number of CAG nucleotide repeats. As a result, the translated protein huntingtin contains disease-causing expansions of glutamines (polyQ) that make it prone to misfold and aggregate. While the gene and mutations that cause HD are known, the mechanisms underlying HD pathogenesis are not. Here we will review the state of knowledge of HD, focusing especially on a hallmark pathological feature-intracellular aggregates of mutant Htt called inclusion bodies (IBs). We will describe the role of IBs in the disease. We speculate that IB formation could be just one component of a broader coping response triggered by misfolded Htt whose efficacy may depend on the extent to which it clears toxic forms of mutant Htt. We will describe how IB formation might be regulated and which factors could determine different coping responses in different subsets of neurons. A differential regulation of IB formation as a function of the cellular context could, eventually, explain part of the neuronal vulnerability observed in HD. PMID:22200539

  3. Preparation and Characterization of Au/Pd Modified-TiO2 Photocatalysts for Phenol and Toluene Degradation under Visible Light—The Effect of Calcination Temperature

    Directory of Open Access Journals (Sweden)

    Anna Cybula

    2014-01-01

    Full Text Available Rutile loaded with Au/Pd nanoparticles was prepared using a water-in-oil microemulsion system of water/AOT/cyclohexane followed by calcination. The effect of calcination temperature (from 350 to 700°C on the structure of Au/Pd nanoparticles deposited at rutile matrix and the photocatalytic properties of Au/Pd-TiO2 was investigated in two model reactions (toluene degradation in gas phase and phenol degradation in aqueous phase. Toluene was irradiated over Au/Pd-TiO2 using light emitting diodes (LEDs, λmax⁡ = 415 nm. The sample 0.5 mol% Pd/TiO2 exhibited the highest activity under visible light irradiation in gas and aqueous phase reaction among all photocatalysts calcined at 350°C, while the sample modified only with gold nanoparticles showed the lowest activity. The Au/Pd-TiO2 sample calcinated at 350°C possesses the highest photocatalytic activity when degrading phenol under visible light, which is 14 times higher than that of the one calcinated at 450°C. It was observed that increasing temperature from 350 to 700°C during calcination step caused segregation of metals and finally resulted in photoactivity drop.

  4. Tailored temperature window of CuOx/WOx–ZrO2 for NOx reduction via adjusting the calcination temperature of WOx–ZrO2

    International Nuclear Information System (INIS)

    WOx–ZrO2 support was calcined at various temperatures for obtaining controllable activity of copper catalysts for NOx reduction by ammonia. The temperature window of copper catalyst for over 80% NOx conversion shifts from 180–300 to 230–350 °C by elevating the calcination temperature of WOx–ZrO2 support from 500 to 600 °C, due to the increased Brønsted acidity and reduced structure and electronic interactions between copper oxides and tungsten oxides arising from the polymerization of WOx clusters on surface of support. Calcining WOx–ZrO2 support at 700 °C leads to the reduced redox property of copper oxides on the Cu–O–W interface and the formation of bulk-like CuO, results in a low activity of catalyst. - Graphical abstract: The temperature window of catalyst for over 80% NOx conversion shifts from 180-300 °C to 230–350 °C by elevating the calcination temperature of WOx–ZrO2 support from 500 °C to 600 °C. Highlights: ► The temperature window of catalyst is tailored by calcining the support. ► The mechanisms of tailoring the temperature window of catalyst are discussed. ► The polymerization of WOx leads to the increased Brønsted acidity of catalysts. ► The CuOx/WOx interactions are reduced by elevating calcination temperature of support

  5. Effects of calcination temperature on Mn species and catalytic activities of Mn/ZSM-5 catalyst for selective catalytic reduction of NO with ammonia

    International Nuclear Information System (INIS)

    A series of Mn/ZSM-5 catalysts for the selective catalytic reduction of NO with NH3 was prepared by precipitation method at different calcination temperature. X-ray diffraction, X-ray photoelectron spectroscopy, H2 temperature-programmed reduction and N2 adsorption/desorption technologies were conducted to explore the effects of calcination temperature on the physical and chemical properties of Mn/ZSM-5 catalysts. Results suggested that when calcined at lower temperatures (x existed in the form of Mn3O4 and amorphous MnO2 on the catalyst surface. However, when calcined at 600 °C Mn2O3 species which is unfavorable for the SCR process were formed and became the major phase at 700 °C. On the other hand, with the increase of calcination temperatures, the surface Mn concentration and the specific surface area of catalysts both decreased. The catalytic activity test indicated that the Mn/ZSM-5 catalyst calcined at 300 °C demonstrated the best performance for NO removal, with almost 100% NO conversion in the range of 150–390 °C. According to the characterization results, the enrichment of surface Mn, surface Mn3O4 and amorphous MnO2 species may account for its superior catalytic activity.

  6. Asphaltene Aggregation and Fouling Behavior

    Science.gov (United States)

    Derakhshesh, Marzie

    This thesis explored the properties of asphaltene nano-aggregates in crude oil and toluene based solutions and fouling at process furnace temperatures, and the links between these two phenomena. The link between stability of asphaltenes at ambient conditions and fouling at the conditions of a delayed coker furnace, at over 450 °C, was examined by blending crude oil with an aliphatic diluent in different ratios. The stability of the blends were measured using a S-value analyzer, then fouling rates were measured on electrically heated stainless steel 316 wires in an autoclave reactor. The less stable the blend, the greater the rate and extent of fouling. The most severe fouling occurred with the unstable asphaltenes. SEM imaging of the foulant illustrates very different textures, with the structure becoming more porous with lower stability. Under cross-polarized light, the coke shows the presence of mesophase in the foulant layer. These data suggest a correlation between the fouling rate at high temperature furnace conditions and the stability index of the crude oil. Three organic polysulfides were introduced to the crude oil to examine their effect on fouling. The polysulfides are able to reduce coking and carbon monoxide generation in steam crackers. The fouling results demonstrated that polysulfide with more sulfur content increased the amount of corrosion-fouling of the wire. Various additives, solvents, ultrasound, and heat were employed to attempt to completely disaggregate the asphaltene nano-aggregates in solution at room temperature. The primary analytical technique used to monitor the nano-aggregation state of the asphaltenes in solution was the UV-visible spectroscopy. The results indicate that stronger solvents, such as pyridine and quinoline, combined with ionic liquids yield a slight reduction in the apparent absorbance at longer wavelengths, indicative of a decrease in the nano-aggregate size although the magnitude of the decrease is not significant

  7. One-dimensional long-range diffusion-limited aggregation III -- The limit aggregate

    CERN Document Server

    Amir, Gideon

    2009-01-01

    In this paper we study the structure of the limit aggregate (the union of all finite-time aggregates) of the one-dimensional long range diffusion limited aggregation process defined in [arXiv:0910.4416] . We show (under some regularity conditions) that for walks with finite third moment the limit aggregate has renewal structure and positive density, while for walks with finite variance the renewal structure no longer exists and the limit aggregate has 0 density. We define a tree structure on the aggregates and show some results on the degrees and number of ends of these random trees.

  8. A vertically resolved model for phytoplankton aggregation

    Indian Academy of Sciences (India)

    Iris Kriest; Geoffrey T Evans

    2000-12-01

    This work presents models of the vertical distribution and flux of phytoplankton aggregates, including changes with time in the distribution of aggregate sizes and sinking speeds. The distribution of sizes is described by two parameters, the mass and number of aggregates, which greatly reduces the computational cost of the models. Simple experiments demonstrate the effects of aggregation on the timing and depth distribution of primary production and export. A more detailed ecological model is applied to sites in the Arabian Sea; it demonstrates that aggregation can be important for deep sedimentation even when its effect on surface concentrations is small, and it presents the difference in timing between settlement of aggregates and fecal pellets.

  9. Aggregation server for grid-integrated vehicles

    Science.gov (United States)

    Kempton, Willett

    2015-05-26

    Methods, systems, and apparatus for aggregating electric power flow between an electric grid and electric vehicles are disclosed. An apparatus for aggregating power flow may include a memory and a processor coupled to the memory to receive electric vehicle equipment (EVE) attributes from a plurality of EVEs, aggregate EVE attributes, predict total available capacity based on the EVE attributes, and dispatch at least a portion of the total available capacity to the grid. Power flow may be aggregated by receiving EVE operational parameters from each EVE, aggregating the received EVE operational parameters, predicting total available capacity based on the aggregated EVE operational parameters, and dispatching at least a portion of the total available capacity to the grid.

  10. Influence of shear stress on erythrocyte aggregation.

    Science.gov (United States)

    Kim, Jeong-Ho; Lee, Hoyoon; Lee, Byoung-Kwon; Shin, Sehyun

    2015-09-25

    Shear stress is known to induce platelet activation and aggregation. The red blood cell (RBC) aggregation test requires the application of shear stress for the cells to disaggregate for initialization. We tested the hypothesis that applying shear stress may activate platelets, which can influence RBC aggregation. The present study used a commercial microchip-based aggregometer (RheoSCan-AnD300) with a rotating stirrer for RBC disaggregation. Whole blood samples were exposed to different magnitudes of shear stress with various shearing times. As the rotational speed was increased up to 2800 rpm, the RBC aggregation index (AI) of the whole blood increased by up to 30% (p <  0.05), whereas that of the platelet-excluded blood samples did not show any apparent alteration. The AI also increased in proportion with the stirring time. The data suggest that high shear stress affects RBC aggregation through shear-induced platelet aggregation. PMID:26444600

  11. A dimension map for molecular aggregates.

    Science.gov (United States)

    Jian, Cuiying; Tang, Tian; Bhattacharjee, Subir

    2015-05-01

    A pair of gyradius ratios, defined from the principal radii of gyration, are used to generate a dimension map that describes the geometry of molecular aggregates in water and in organic solvents. Molecular dynamics simulations were performed on the aggregation of representative biomolecules and polyaromatic compounds to demonstrate application of the dimension map. It was shown that molecular aggregate data on the dimension map were bounded by two boundary curves, and that the map could be separated into three regions representing three groups of structures: one-dimensional rod-like structures; two-dimensional planar structures or short-cylinder-like structures; and three-dimensional sphere-like structures. Examining the location of the aggregates on the dimension map and how the location changes with solvent type and solute material parameter provides a simple yet effective way to infer the aggregation manner and to study solubility and mechanism of aggregation. PMID:25768393

  12. Recycled aggregate concrete exposed to elevated temperature

    OpenAIRE

    Arundeb Gupta; Saroj Mandal; Somnath Ghosh

    2012-01-01

    An experimental investigation has been conducted to study the mechanical as well as micro structural properties of Recycled aggregate concrete (RAC) exposed to elevated temperature. Fly ash (as replacement of cement) was added while making concrete. Recycled aggregates are mixed with natural aggregates also to prepare concrete. Cubes and cylinder test specimens were prepared and cured under water for 28 days. Test specimens were exposed to different levels of temperature (200oC, 400oC, 600oC,...

  13. Constraint Aggregation Principle in Convex Optimization

    OpenAIRE

    Y.M. Ermoliev; Kryazhimskiy, A.V.; Ruszczynski, A.

    1995-01-01

    A general constraint aggregation technique is proposed for convex optimization problems. At each iteration a set of convex inequalities and linear equations is replaced by a single inequality formed as a linear combination of the original constraints. After solving the simplified subproblem, new aggregation coefficients are calculated and the iteration continues. This general aggregation principle is incorporated into a number of specific algorithms. Convergence of the new methods is pro...

  14. Linguistic Weighted Aggregation under Confidence Levels

    OpenAIRE

    2015-01-01

    We develop some new linguistic aggregation operators based on confidence levels. Firstly, we introduce the confidence linguistic weighted averaging (CLWA) operator and the confidence linguistic ordered weighted averaging (CLOWA) operator. These two new linguistic aggregation operators are able to consider the confidence level of the aggregated arguments provided by the information providers. We also study some of their properties. Then, based on the generalized means, we introduce the confide...

  15. Simulations of kinetically irreversible protein aggregate structure.

    OpenAIRE

    Patro, S Y; Przybycien, T M

    1994-01-01

    We have simulated the structure of kinetically irreversible protein aggregates in two-dimensional space using a lattice-based Monte-Carlo routine. Our model specifically accounts for the intermolecular interactions between hydrophobic and hydrophilic protein surfaces and a polar solvent. The simulations provide information about the aggregate density, the types of inter-monomer contacts and solvent content within the aggregates, the type and extent of solvent exposed perimeter, and the short-...

  16. Familial aggregation analysis of gene expressions

    OpenAIRE

    Rao Shao-Qi; Xu Liang-De; Zhang Guang-Mei; Li Xia; Li Lin; Shen Gong-Qing; Jiang Yang; Yang Yue-Ying; Gong Bin-Sheng; Jiang Wei; Zhang Fan; Xiao Yun; Wang Qing K

    2007-01-01

    Abstract Traditional studies of familial aggregation are aimed at defining the genetic (and non-genetic) causes of a disease from physiological or clinical traits. However, there has been little attempt to use genome-wide gene expressions, the direct phenotypic measures of genes, as the traits to investigate several extended issues regarding the distributions of familially aggregated genes on chromosomes or in functions. In this study we conducted a genome-wide familial aggregation analysis b...

  17. Making Sense of the Aggregator Bank

    OpenAIRE

    2009-01-01

    On Tuesday, 10 February 2009, Treasury Secretary Geithner proposed the aggregator bank (“public-private investment fund”) as a key instrument to resolve the financial crisis (www.financialstability.gov). The Treasury description leaves many issues unanswered. Here we explain how an aggregator bank might operate in practice. We fill in some of the major details so as to enhance the effectiveness of the aggregator bank. In particular, the approach emphasizes transparency and value to the taxpay...

  18. A File Aggregation Scheme for FLUTE

    OpenAIRE

    Neumann, Christoph; Roca, Vincent; Walsh, Rod

    2005-01-01

    This document introduces a logical and physical file aggregation scheme for File Delivery over Unidirectional Transport (FLUTE). The logical file aggregation mechanism is a generalized grouping mechanism, allowing to logically group files. The physical file aggregation scheme allows, additionally to a logical grouping, to more efficiently use Forward Error Correction (FEC) in the context of FLUTE, in particular when dealing with a large number of "small" files. Unlike a solution based on the ...

  19. Regulated protein aggregation: stress granules and neurodegeneration

    OpenAIRE

    Wolozin Benjamin

    2012-01-01

    Abstract The protein aggregation that occurs in neurodegenerative diseases is classically thought to occur as an undesirable, nonfunctional byproduct of protein misfolding. This model contrasts with the biology of RNA binding proteins, many of which are linked to neurodegenerative diseases. RNA binding proteins use protein aggregation as part of a normal regulated, physiological mechanism controlling protein synthesis. The process of regulated protein aggregation is most evident in formation ...

  20. Temporal aggregation of an ESTAR process

    OpenAIRE

    I Paya; Peel, D

    2005-01-01

    Nonlinear models of deviations from PPP have recently provided an important, theoretically well motivated, contribution to the PPP puzzle. Most of these studies use temporally aggregated data to empirically estimate the nonlinear models. As noted by Taylor (2001), if the true DGP is nonlinear, the temporally aggregated data could exhibit misleading properties regarding the adjustment speeds. We examine the effects of different levels of temporal aggregation on estimates of ESTAR models of rea...