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Sample records for caustic leach rate

  1. EFRT M-12 Issue Resolution: Caustic Leach Rate Constants from PEP and Laboratory-Scale Tests

    Energy Technology Data Exchange (ETDEWEB)

    Mahoney, Lenna A.; Rassat, Scot D.; Eslinger, Paul W.; Aaberg, Rosanne L.; Aker, Pamela M.; Golovich, Elizabeth C.; Hanson, Brady D.; Hausmann, Tom S.; Huckaby, James L.; Kurath, Dean E.; Minette, Michael J.; Sundaram, S. K.; Yokuda, Satoru T.

    2009-08-14

    concentrated to nominally 20 wt% solids using cross-flow ultrafiltration before adding caustic. The work described in this report addresses the kinetics of caustic leach under WTP conditions, based on tests performed with a Hanford waste simulant. The tests were completed at the lab-scale and in the PEP, which is a 1/4.5-scale mock-up of key PTF process equipment. The purpose of this report is to summarize the results from both scales that are related to caustic leach chemistry to support a scale-up factor for the submodels to be used in the G2 model, which predicts WTP operating performance. The scale-up factor will take the form of an adjustment factor for the rate constant in the boehmite leach kinetic equation in the G2 model.

  2. EFRT M-12 Issue Resolution: Caustic-Leach Rate Constants from PEP and Laboratory-Scale Tests

    Energy Technology Data Exchange (ETDEWEB)

    Mahoney, Lenna A.; Rassat, Scot D.; Eslinger, Paul W.; Aaberg, Rosanne L.; Aker, Pamela M.; Golovich, Elizabeth C.; Hanson, Brady D.; Hausmann, Tom S.; Huckaby, James L.; Kurath, Dean E.; Minette, Michael J.; Sundaram, S. K.; Yokuda, Satoru T.

    2010-01-01

    Pacific Northwest National Laboratory (PNNL) has been tasked by Bechtel National Inc. (BNI) on the River Protection Project-Hanford Tank Waste Treatment and Immobilization Plant (RPP-WTP) project to perform research and development activities to resolve technical issues identified for the Pretreatment Facility (PTF). The Pretreatment Engineering Platform (PEP) was designed, constructed and operated as part of a plan to respond to issue M12, “Undemonstrated Leaching Processes” of the External Flowsheet Review Team (EFRT) issue response plan.( ) The PEP is a 1/4.5-scale test platform designed to simulate the WTP pretreatment caustic leaching, oxidative leaching, ultrafiltration solids concentration, and slurry washing processes. The PEP replicates the WTP leaching processes using prototypic equipment and control strategies. The PEP also includes non-prototypic ancillary equipment to support the core processing. The work described in this report addresses caustic leaching under WTP conditions, based on tests performed with a Hanford waste simulant. Because gibbsite leaching kinetics are rapid (gibbsite is expected to be dissolved by the time the final leach temperature is reached), boehmite leach kinetics are the main focus of the caustic-leach tests. The tests were completed at the laboratory-scale and in the PEP, which is a 1/4.5-scale mock-up of key PTF process equipment. Two laboratory-scale caustic-leach tests were performed for each of the PEP runs. For each PEP run, unleached slurry was taken from the PEP caustic-leach vessel for one batch and used as feed for both of the corresponding laboratory-scale tests.

  3. Caustic Leaching of Hanford Tank S-110 Sludge

    Energy Technology Data Exchange (ETDEWEB)

    Lumetta, Gregg J.; Carson, Katharine J.; Darnell, Lori P.; Greenwood, Lawrence R.; Hoopes, Francis V.; Sell, Richard L.; Sinkov, Sergey I.; Soderquist, Chuck Z.; Urie, Michael W.; Wagner, John J.

    2001-10-31

    This report describes the Hanford Tank S-110 sludge caustic leaching test conducted in FY 2001 at the Pacific Northwest National Laboratory. The data presented here can be used to develop the baseline and alternative flowsheets for pretreating Hanford tank sludge. The U.S. Department of Energy funded the work through the Efficient Separations and Processing Crosscutting Program (ESP; EM﷓50).

  4. Laboratory Demonstration of the Pretreatment Process with Caustic and Oxidative Leaching Using Actual Hanford Tank Waste

    Energy Technology Data Exchange (ETDEWEB)

    Fiskum, Sandra K.; Billing, Justin M.; Buck, Edgar C.; Daniel, Richard C.; Draper, Kathryn E.; Edwards, Matthew K.; Jenson, Evan D.; Kozelisky, Anne E.; MacFarlan, Paul J.; Peterson, Reid A.; Shimskey, Rick W.; Snow, Lanee A.

    2009-01-01

    This report describes the bench-scale pretreatment processing of actual tank waste materials through the entire baseline WTP pretreatment flowsheet in an effort to demonstrate the efficacy of the defined leaching processes on actual Hanford tank waste sludge and the potential impacts on downstream pretreatment processing. The test material was a combination of reduction oxidation (REDOX) tank waste composited materials containing aluminum primarily in the form of boehmite and dissolved S saltcake containing Cr(III)-rich entrained solids. The pretreatment processing steps tested included • caustic leaching for Al removal • solids crossflow filtration through the cell unit filter (CUF) • stepwise solids washing using decreasing concentrations of sodium hydroxide with filtration through the CUF • oxidative leaching using sodium permanganate for removing Cr • solids filtration with the CUF • follow-on solids washing and filtration through the CUF • ion exchange processing for Cs removal • evaporation processing of waste stream recycle for volume reduction • combination of the evaporated product with dissolved saltcake. The effectiveness of each process step was evaluated by following the mass balance of key components (such as Al, B, Cd, Cr, Pu, Ni, Mn, and Fe), demonstrating component (Al, Cr, Cs) removal, demonstrating filterability by evaluating filter flux rates under various processing conditions (transmembrane pressure, crossflow velocities, wt% undissolved solids, and PSD) and filter fouling, and identifying potential issues for WTP. The filterability was reported separately (Shimskey et al. 2008) and is not repeated herein.

  5. Washing and Caustic Leaching of Hanford Tank Sludge: Results of FY 1998 Studies

    Energy Technology Data Exchange (ETDEWEB)

    GJ Lumetta; BM Rapko; J Liu; DJ Temer; RD Hunt

    1998-12-11

    Sludge washing and parametric caustic leaching tests were performed on sludge samples tiom five Hanford tanks: B-101, BX-1 10, BX-112, C-102, and S-101. These studies examined the effects of both dilute hydroxide washing and caustic leaching on the composition of the residual sludge solids. ` Dilute hydroxide washing removed from <1 to 25% of the Al, -20 to 45% of the Cr, -25 to 97% of the P, and 63 to 99% of the Na from the Hdord tank sludge samples examined. The partial removal of these elements was likely due to the presence of water-soluble sodium salts of aluminate, chromate, hydroxide, nitrate, nitrite, and phosphate, either in the interstitial liquid or as dried salts.

  6. Caustic leaching of high-level radioactive tank sludge: A critical literature review

    Energy Technology Data Exchange (ETDEWEB)

    McGinnis, C.P.; Welch, T.D.; Hunt, R.D.

    1998-08-01

    The Department of Energy (DOE) must treat and safely dispose of its radioactive tank contents, which can be separated into high-level waste (HLW) and low-level waste (LLW) fractions. Since the unit costs of treatment and disposal are much higher for HLW than for LLW, technologies to reduce the amount of HLW are being developed. A key process currently being studied to reduce the volume of HLW sludges is called enhanced sludge washing (ESW). This process removes, by water washes, soluble constituents such as sodium salts, and the washed sludge is then leached with 2--3 M NaOH at 60--100 C to remove nonradioactive metals such as aluminum. The remaining solids are considered to be HLW while the solutions are LLW after radionuclides such as {sup 137}Cs have been removed. Results of bench-scale tests have shown that the ESW will probably remove the required amounts of inert constituents. While both experimental and theoretical results have shown that leaching efficiency increases as the time and temperature of the leach are increased, increases in the caustic concentration above 2--3 M will only marginally improve the leach factors. However, these tests were not designed to validate the assumption that the caustic used in the ESW process will generate only a small increase (10 Mkg) in the amount of LLW; instead the test conditions were selected to maximize leaching in a short period and used more water and caustic than is planned during full-scale operations. Even though calculations indicate that the estimate for the amount of LLW generated by the ESW process appears to be reasonable, a detailed study of the amount of LLW from the ESW process is still required. If the LLW analysis indicates that sodium management is critical, then a more comprehensive evaluation of the clean salt process or caustic recycle would be needed. Finally, experimental and theoretical studies have clearly demonstrated the need for the control of solids formation during and after leaching.

  7. Mechanism of Phosphorus Removal from Hanford Tank Sludge by Caustic Leaching

    Energy Technology Data Exchange (ETDEWEB)

    Lumetta, Gregg J. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

    2008-03-05

    Two experiments were conducted to explore the mechanism by which phosphorus is removed from Hanford tank sludge by caustic leaching. In the first experiment, a series of phosphate salts were treated with 3 M NaOH under conditions prototypic of the actual leaching process to be performed in the Waste Treatment and Immobilization Plant (WTP). The phosphates used were aluminum phosphate, bismuth phosphate, chromium(III) phosphate, and β-tri-calcium phosphate; all of these phases have previously been determined to exist in Hanford tank sludge. The leachate solution was sampled at selected time intervals and analyzed for the specific metal ion involved (Al, Bi, Ca, or Cr) and for P (total and as phosphate). The solids remaining after completion of the caustic leaching step were analyzed to determine the reaction product. In the second experiment, the dependence of P removal from bismuth phosphate was examined as a function of the hydroxide ion concentration. It was anticipated that a plot of log[phosphate] versus log[hydroxide] would provide insight into the phosphorus-removal mechanism. This report describes the test activities outlined in Section 6.3.2.1, Preliminary Investigation of Phosphate Dissolution, in Test Plan TP-RPP-WTP-467, Rev.1. The objectives, success criteria, and test conditions of Section 6.3.2.1 are summarized here.

  8. PEP Integrated Test D Run Report Caustic and Oxidative Leaching in UFP-VSL-T02A

    Energy Technology Data Exchange (ETDEWEB)

    Sevigny, Gary J.; Bredt, Ofelia P.; Burns, Carolyn A.; Kurath, Dean E.; Geeting, John GH; Golovich, Elizabeth C.; Guzman-Leong, Consuelo E.; Josephson, Gary B.

    2009-12-11

    Pacific Northwest National Laboratory (PNNL) has been tasked by Bechtel National Inc. (BNI) on the River Protection Project-Hanford Tank Waste Treatment and Immobilization Plant (RPP-WTP) project to perform research and development activities to resolve technical issues identified for the Pretreatment Facility (PTF). The Pretreatment Engineering Platform (PEP) was designed, constructed and operated as part of a plan to respond to issue M12, "Undemonstrated Leaching Processes" of the External Flowsheet Review Team (EFRT) issue response plan. The PEP is a 1/4.5-scale test platform designed to simulate the WTP pretreatment caustic leaching, oxidative leaching, ultrafiltration solids concentration, and slurry washing processes. The PEP replicates the WTP leaching processes using prototypic equipment and control strategies. The PEP also includes non-prototypic ancillary equipment to support the core processing. Two operating scenarios are currently being evaluated for the ultrafiltration process (UFP) and leaching operations. The first scenario (Test B and D) has caustic leaching performed in the UFP-2 ultrafiltration feed vessels (i.e., vessel UFP-VSL-T02A in the PEP and vessels UFP-VSL-00002A and B in the WTP PTF). The second scenario (Test A) has caustic leaching conducted in the UFP-1 ultrafiltration feed preparation vessels (i.e., vessels UFP-VSL-T01A and B in the PEP and vessels UFP VSL-00001A and B in the WTP PTF). In Test D, 19M sodium hydroxide (NaOH, caustic) was added to the waste slurry in the UFP VSL T02 vessel after the solids were concentrated to ~20% undissolved solids. The NaOH was added to leach solid aluminum compounds (e.g., gibbsite, boehmite). Caustic addition is followed by heating to 85°C using direct injection of steam to accelerate the leach process. The main difference of Test D compared to Test B is that the leach temperature is 85°C for 24 hrs as compared to 100°C for 12 hours. The other difference is the Test D simulant had Cr in the

  9. Washing and caustic leaching of Hanford tank sludges: results of FY 1996 studies. Revision

    International Nuclear Information System (INIS)

    During the past few years, the primary mission at the US Department of Energy's Hanford Site has changed from producing plutonium to restoring the environment. Large volumes of high-level radioactive wastes (HLW), generated during past Pu production and other operations, are stored in underground tanks on site. The current plan for remediating the Hanford tank farms consists of waste retrieval, pretreatment, treatment (immobilization), and disposal. The HLW will be immobilized in a borosilicate glass matrix and then disposed of in a geologic repository. Because of the expected high cost of HLW vitrification and geologic disposal, pretreatment processes will be implemented to reduce the volume of borosilicate glass produced in disposing of the tank wastes. On this basis, a pretreatment plan is being developed. This report describes the sludge washing and caustic leaching test conducted to create a Hanford tank sludge pretreatment flowsheet

  10. Extraction of Zinc from Electric Arc Furnace Dust by Alkaline Leaching Followed by Fusion of the Leaching Residue with Caustic Soda

    Institute of Scientific and Technical Information of China (English)

    赵由才; R.Stanforth

    2004-01-01

    Extractability of zinc from two types of electric arc furnace (EAF) dusts containing 24.8% and 16.8% of zinc respectively (denoted as Sample A and Sample B) were tested using direct alkaline leaching followed by fusion of the resulting leaching residues with caustic soda. The experimental results show that the extraction of zinc is heavily dependent on the contents of iron in the dusts. The higher iron content, the lower extraction of zinc is obtained. 53% and 38% of zinc can be extracted when both dusts were directly contacted with 5mol·L-1 NaOH solution for 42h. The remaining zinc left in the leaching residues, which supposed to be present as zinc ferrites, can be further leached when the residues were fused with caustic soda. Quantitative extraction of zinc can be obtained from the leaching residue of Sample A while only 85% from Sample B. The extractability of zinc from dusts wit hvarious contents of iron is compared. The production flowsheet for zinc from the dusts using the process proposed is discussed.

  11. PEP Run Report for Integrated Test A, Caustic Leaching in UFP-VSL-T01A, Oxidative Leaching in UFP-VSL-T02A

    Energy Technology Data Exchange (ETDEWEB)

    Guzman-Leong, Consuelo E.; Bredt, Ofelia P.; Burns, Carolyn A.; Daniel, Richard C.; Su, Yin-Fong; Geeting, John GH; Golovich, Elizabeth C.; Josephson, Gary B.; Kurath, Dean E.; Sevigny, Gary J.; Smith, Dennese M.; Valdez, Patrick LJ; Yokuda, Satoru T.; Young, Joan K.

    2009-12-04

    Pacific Northwest National Laboratory (PNNL) was tasked by Bechtel National Inc. (BNI) on the River Protection Project-Hanford Tank Waste Treatment and Immobilization Plant (RPP-WTP) project to perform research and development activities to resolve technical issues identified for the Pretreatment Facility (PTF). The Pretreatment Engineering Platform (PEP) was designed and constructed and operated as part of a plan to respond to issue M12, “Undemonstrated Leaching Processes.”(a) The PEP, located in the Process Engineering Laboratory-West (PDLW) located in Richland, Washington, is a 1/4.5-scale test platform designed to simulate the WTP pretreatment caustic leaching, oxidative leaching, ultrafiltration solids concentration, and slurry washing processes. The PEP replicates the WTP leaching processes using prototypic equipment and control strategies. The PEP also includes non-prototypic ancillary equipment to support the core processing.

  12. Washing and caustic leaching of Hanford tank sludges: Results of FY 1995 studies

    International Nuclear Information System (INIS)

    During the past few years, the primary mission at the US Department of Energy's Hanford Site has changed from producing plutonium to environmental restoration. Large volumes of high-level radioactive wastes (HLW), generated during past Pu production and other operations, are stored in underground tanks on site. The current plan for remediating the Hanford tank farms consists of waste retrieval, pretreatment, treatment (immobilization), and disposal. The HLW will be immobilized in a borosilicate glass matrix; the resulting glass canisters will then be disposed of in a geologic repository. Because of the expected high cost of HLW immobilization and disposal, pretreatment processes will be implemented to reduce the volume of borosilicate glass produced in processing the tank wastes. This document describes sludge washing and caustic leaching tests conducted in FY 1995 at the Pacific Northwest Laboratory (PNL) at the request of Westinghouse Hanford Company. These tests were performed using sludges from seven Hanford waste tanks -- B-111, BX-107, C-103, S-104, SY-103, T-104, and T-111. The primary and secondary types of waste stored in each of these tanks are given in Table 1. 1. The data collected in this effort will be used to support the March 1998 Tri-Party Agreement decision on the extent of pretreatment to be performed on the Hanford tank sludges (Ecology, EPA, and DOE 1994)

  13. Increasing silver leaching rate from leaching-resistant zinc residues by thiourea leaching method with pressurized preoxidation process

    Institute of Scientific and Technical Information of China (English)

    胡天觉; 曾光明; 黄国和; 袁兴中; 李建兵

    2003-01-01

    As for the leaching-resistant zinc residues, the silver leaching rate can be over 98% through the processof pressurized preoxidation and thiourea leaching. Compared with the method of extracting the silver directly fromthe leaching-resistant zinc residues, the silver leaching rate is greatly improved. The optimum preoxidation condi-tions are: particle size range 40 - 60 μm, oxygen partial pressure 106 Pa, temperature 80 - 90 ℃, pH= 1.0, andleaching time 5 h. After pretreatment, the time of thiourea leaching silver is shortened to 1.5 h, and the thioureaconsumption is reduced greatly. The oxidation mechanism and the thiourea leaching kinetics were also explored.

  14. Water washes and caustic leaches of sludge from Hanford Tank S-101 and water washes of sludge from Hanford Tank C-103

    International Nuclear Information System (INIS)

    In 1993, the Department of Energy (DOE) selected the enhanced sludge washing (ESW) process as the baseline for pretreatment of Hanford tank sludges. The ESW process uses a series of water washes and caustic leaches to separate nonradioactive components such as aluminum, chromium, and phosphate from the high-level waste sludges. If the ESW process is successful, the volume of immobilized high-level waste will be significantly reduced. The tests on the sludge from Hanford Tank S-101 focused on the effects of process variables such as sodium hydroxide concentration (1 and 3 M), temperature (70 and 95 C), and leaching time (5, 24, 72, and 168 h) on the efficacy of the ESW process with realistic liquid-to-solid ratios. Another goal of this study was to evaluate the effectiveness of water washes on a sludge sample from hanford Tank C-103. The final objective of this study was to test potential process control monitors during the water washes and caustic leaches with actual sludge. Both 137Cs activity and conductance were measured for each of the water washes and caustic leaches. Experimental procedures, a discussion of results, conclusions and recommendations are included in this report

  15. Water washes and caustic leaches of sludge from Hanford Tank S-101 and water washes of sludge from Hanford Tank C-103

    Energy Technology Data Exchange (ETDEWEB)

    Hunt, R.D.; Collins, J.L.; Chase, C.W.

    1998-07-01

    In 1993, the Department of Energy (DOE) selected the enhanced sludge washing (ESW) process as the baseline for pretreatment of Hanford tank sludges. The ESW process uses a series of water washes and caustic leaches to separate nonradioactive components such as aluminum, chromium, and phosphate from the high-level waste sludges. If the ESW process is successful, the volume of immobilized high-level waste will be significantly reduced. The tests on the sludge from Hanford Tank S-101 focused on the effects of process variables such as sodium hydroxide concentration (1 and 3 M), temperature (70 and 95 C), and leaching time (5, 24, 72, and 168 h) on the efficacy of the ESW process with realistic liquid-to-solid ratios. Another goal of this study was to evaluate the effectiveness of water washes on a sludge sample from hanford Tank C-103. The final objective of this study was to test potential process control monitors during the water washes and caustic leaches with actual sludge. Both {sup 137}Cs activity and conductance were measured for each of the water washes and caustic leaches. Experimental procedures, a discussion of results, conclusions and recommendations are included in this report.

  16. Pretreatment Engineering Platform (PEP) Integrated Test B Run Report--Caustic and Oxidative Leaching in UFP-VSL-T02A

    Energy Technology Data Exchange (ETDEWEB)

    Geeting, John GH; Bredt, Ofelia P.; Burns, Carolyn A.; Golovich, Elizabeth C.; Guzman-Leong, Consuelo E.; Josephson, Gary B.; Kurath, Dean E.; Sevigny, Gary J.; Aaberg, Rosanne L.

    2009-12-10

    Pacific Northwest National Laboratory (PNNL) has been tasked by Bechtel National Inc. (BNI) on the River Protection Project-Hanford Tank Waste Treatment and Immobilization Plant (RPP-WTP) project to perform research and development activities to resolve technical issues identified for the Pretreatment Facility (PTF). The Pretreatment Engineering Platform (PEP) was designed, constructed and operated as part of a plan to respond to issue M12, “Undemonstrated Leaching Processes” of the External Flowsheet Review Team (EFRT) issue response plan.( ) The PEP is a 1/4.5-scale test platform designed to simulate the WTP pretreatment caustic leaching, oxidative leaching, ultrafiltration solids concentration, and slurry washing processes. The PEP replicates the WTP leaching processes using prototypic equipment and control strategies. The PEP also includes non-prototypic ancillary equipment to support the core processing.

  17. PEP Support: Laboratory Scale Leaching and Permeate Stability Tests

    Energy Technology Data Exchange (ETDEWEB)

    Russell, Renee L.; Peterson, Reid A.; Rinehart, Donald E.; Buchmiller, William C.

    2010-05-21

    This report documents results from a variety of activities requested by the Hanford Tank Waste Treatment and Immobilization Plant (WTP). The activities related to caustic leaching, oxidative leaching, permeate precipitation behavior of waste as well as chromium (Cr) leaching are: • Model Input Boehmite Leaching Tests • Pretreatment Engineering Platform (PEP) Support Leaching Tests • PEP Parallel Leaching Tests • Precipitation Study Results • Cr Caustic and Oxidative Leaching Tests. Leaching test activities using the PEP simulant provided input to a boehmite dissolution model and determined the effect of temperature on mass loss during caustic leaching, the reaction rate constant for the boehmite dissolution, and the effect of aeration in enhancing the chromium dissolution during caustic leaching. Other tests were performed in parallel with the PEP tests to support the development of scaling factors for caustic and oxidative leaching. Another study determined if precipitate formed in the wash solution after the caustic leach in the PEP. Finally, the leaching characteristics of different chromium compounds under different conditions were examined to determine the best one to use in further testing.

  18. Distribution of velocity gradients and rate of caustic formation in turbulent aerosols at finite Kubo numbers

    CERN Document Server

    Gustavsson, K

    2012-01-01

    In a one-dimensional model for a turbulent aerosol (inertial particles suspended in a random flow) we compute the distributions of particle-velocity gradients and the rate of caustic formation at finite but small Kubo numbers Ku, for arbitrary Stokes numbers St. Our results are consistent with those obtained earlier in the limit of small Ku and and large St, such that Ku^2 St remains constant. We show how finite-time correlations and non-ergodic effects influence the inertial-particle dynamics at finite but small Kubo numbers.

  19. Prediction of leaching rate in heap leaching process by grey dynamic model GDM(1,1)

    Institute of Scientific and Technical Information of China (English)

    LIU Jin-zhi; wu Ai-xiang

    2008-01-01

    The method of developing GM(1,1)model is extended on the basis of grey system theory.Conditions for the transfer function that improve smoothness of original data sequence and decrease the revert error are given.The grey dynamic model is first combined with the transfer function to predict the leaching rate in heap leaching process.The resuhs show that high prediction accuracy call be expected by using the proposed method.This provides a new approach to realize prediction and control of the future behavior of leaching kinetics.

  20. Low leach rate glasses for immobilization of nuclear wastes

    International Nuclear Information System (INIS)

    Improved defense and commercial waste glass have about one order of magnitude lower leach rates at 900C in static deionized water than reference glasses. This durability difference diminishes as the leaching temperature is raised, but at repository temperature less than 1500C, the improved compositions would have considerable advantages over reference glases. At the melting temperatures necessary for most of the high-durability glasses, volatility was found to be higher than that experienced in processing current reference glases. Higher volatilities might be compensated for by specific design of the off-gas system for improved off-gas treatment and volatile materials recovery. 6 figures, 2 tables

  1. Assessment of weathering and leaching rates of Thule hot particles

    Energy Technology Data Exchange (ETDEWEB)

    Roos, P. (Technical Univ. of Denmark, Risoe National Laboratory for Sustainable Energy, Roskilde (Denmark)); Outola, I. (STUK-Radiation and Nuclear Safety Authority (Finland)); Nygren, U.; Ramebaeck, H. (FOI CBRN Defence and Security (Sweden)); Sidhu, R. (Institute of Energy Technology, Environmental Monitoring Section, Health and Safety Dept. (Norway))

    2010-03-15

    Within the current project a methodology for separating actinide particles originating from the Thule 1968 accident has been developed. Particles were completely isolated in water using visual and radiometric methods. The particles were attached electrostatic to a plastic support and could easily be moved to any container for leaching studies or other type of studies. Leaching and dissolution studies performed within the project indicate that some particles are relatively easily destroyed or leached while others are more refractory. The results shows that even though the oxide particles are hard to completely dissolve they release material even when exposed to weak solvents like water and salt solutions. Exposures to lung simulant fluids show relatively slow dissolution rates comparable to what is found using only water. Sequential extraction of particles shows that variation between particles is very large; some dissolve easily while some does not. Of radiological importance is the disruption of particles when exposed to dissolution. (author)

  2. Leaching of Natural Gravel and Concrete by CO2 - Experimental Design, Leaching Behaviour and Dissolution Rates

    Science.gov (United States)

    Fuchs, Rita; Leis, Albrecht; Mittermayr, Florian; Harer, Gerhard; Wagner, Hanns; Reichl, Peter; Dietzel, Martin

    2015-04-01

    The durability of building material in aggressive aqueous environments is a key factor for evaluating the product quality and application as well as of high economic interest. Therefore, aspects of durability have been frequently investigated with different approaches such as monitoring, modelling and experimental work. In the present study an experimental approach based on leaching behaviour of natural calcite-containing siliceous gravel used as backfill material in tunnelling and sprayed concrete by CO2 was developed. CO2 was introduced to form carbonic acid, which is known as an important agent to induce chemical attack. The goals of this study were (i) to develop a proper experimental design to survey the leaching of building materials on-line, (ii) to decipher individual reaction mechanisms and kinetics and (iii) to estimate time-resolved chemical resistance of the used material throughout leaching. A combined flow through reactor unit was successfully installed, where both open and closed system conditions can be easily simulated by changing flow directions and rates. The chemical compositions of the experimental solutions were adjusted by CO2 addition at pHstat conditions and monitored in-situ by pH/SpC electrodes and by analysing the chemical composition of samples throughout an experimental run. From the obtained data e.g. dissolution rates with respect to calcite were obtained for the gravel material, which were dependent on the individual calcite content of the leached material. The rates were found to reflect the flow rate conditions, and the kinetic data lay within the range expected from dissolution experiments in the CaCO3-CO2-H2O system. In case of concrete the reactions throughout the leaching experiment were complex. Coupled dissolution and precipitation phenomena (e.g. portlandite dissolution, calcite formation) occurred. The coupled reactions can be followed by the evolution of the solution chemistry. The overall rates of elemental removal from

  3. [Caustic ingestions].

    Science.gov (United States)

    Adukauskiene, Dalia; Mazeikiene, Sandra; Rumba, Arvydas; Vizgirdaite, Venta

    2009-01-01

    Caustic ingestions (alkalis, acids) may cause severe chemical burns and lifelong complications, which worsen life quality. Approximately 80% of caustic ingestions occur in children. They mostly intoxicate because of chemical substances kept insecurely or in inappropriate containers. Until now, there is no general opinion about diagnostics and management of caustic ingestions. Therefore, the main aim of this article is accurately represent diagnostic and treatment options believing that this information would help physicians to diagnose caustic ingestions easier and faster, to provide emergency management correctly, and to avoid acute and chronic complications.

  4. Extraction of Zinc from Electric Arc Furnace Dust by Alkaline Leaching Followed by Fusion of the Leaching Residue with Caustic Soda%氢氧化钠浸取-浸取渣熔融法从炼钢厂烟尘中提取锌的研究

    Institute of Scientific and Technical Information of China (English)

    赵由才; R. Stanforth

    2004-01-01

    Extractability of zinc from two types of electric arc furnace (EAF) dusts containing 24.8% and 16.8%of zinc respectively (denoted as Sample A and Sample B) were tested using direct alkaline leaching followed by fusion of the resulting leaching residues with caustic soda. The experimental results show that the extraction of zinc is heavily dependent on the contents of iron in the dusts. The higher iron content, the lower extraction of zinc is obtained. 53% and 38% of zinc can be extracted when both dusts were directly contacted with 5 mol. L-1 NaOH solution for 42 h. The remaining zinc left in the leaching residues, which supposed to be present as zinc ferrites, can be further leached when the residues were fused with caustic soda. Quantitative extraction of zinc can be obtained from the leaching residue of Sample A while only 85% from Sample B. The extractability of zinc from dusts with various contents of iron is compared. The production flowsheet for zinc from the dusts using the process proposed is discussed.

  5. Causticizing process

    Energy Technology Data Exchange (ETDEWEB)

    Engdal, H.

    1987-03-10

    This invention seeks to provide a method in which the soda lye obtained as a result of cellulose cooking process and unslaked lime are used for producing white liquor which can be re-used in the cooking process. In this method, the heat released by the slaking of lime with soda lye is recovered by a high pressure slaking process wherein the heat is transferred, either to the steam separating from the lye, which steam is then led to the desired application, or to some other medium to be heated. The invention is characterized in that the soda lye to be causticized is divided into two parts, one of which is used for the slaking of lime by adding to it all the unslaked lime needed for the causticizing process, and that, following slaking, the two volumes are brought together for the actual causticizing reaction involving the total amount of lye needed. This invention provides the advantage that the amount of lye needed is smaller, and so the temperature can be increased.

  6. The effect of devitrification on leaching rate of glass containing simulated high level liquid waste (HLLW)

    International Nuclear Information System (INIS)

    Effect of devitrification on leaching rate of glass named G1 and G2 each contains 20 wt% and 30wt% of waste has been studied. devitrification of waste - glass has been carried out by heating those specimens at 850oC for 10, 18, 26, 34, 42 and 50 hours respectively. The weight percentage of crystal in waste glass was determined by X-ray diffractometer and leaching rate was determined by soxhlet apparatus at 100oC for 24 hours. The longer heating time, the more weight percentage of crystal is formed. The results show that leaching rate of G2 specimens are higher than those of G1. For G1 the leaching rate at 850oC in 20 times than without heating, and for G2 leaching rate is 15.7 times than without heating. (author)

  7. The rate of caustic crossing microlensing events for Q2237+0305

    CERN Document Server

    Wyithe, J S B; Turner, E L

    2000-01-01

    Spectrophotometric observation of the gravitationally microlensed quasar Q2237+0305 during a High Magnification Event (HME) is potentially a very powerful tool for probing the structure of the quasars accretion disc on scales of less than 10^-8 arc seconds. How often we can expect to observe a HME is dependent on the lens system parameters of galactic transverse velocity, mean microlens mass and the size of the magnified continuum source. We have previously used published microlensed light-curves to obtain expressions for the likely-hood of the values for these parameters (Wyithe, Webster & Turner 1999b,c; Wyithe, Webster, Turner & Mortlock 1999). Here we use this information to investigate the expected rate of SHMEs. We find the average rate of SHMEs as well as the number that we can expect to observe over periods of a decade and of a single observing season. We find that the average SHME rate summed over all images in Q2237+0305 is 1.5\\pm0.6 - 6.3\\pm1.3 events per decade. During the period following...

  8. Sensitivity of radioactive nuclide leaching rate under the sub-surface disposal

    International Nuclear Information System (INIS)

    In order to dispose of radioactive wastes generated from and stored in JAEA in the sub-surface disposal facility, JAEA has studied the safety assessment of sub-surface disposal considering likely scenario and less-likely scenario. Leaching rate of radionuclide from radioactive wastes to permeation water in sub-surface disposal facility is important parameter in the safety assessment because radionuclides contained in activated metal are released to permeation water by the corrosion of metal. In this report, we studied sensitivity of radionuclide leaching rate from radioactive wastes in the safety assessment of sub-surface disposal. As a result, it is confirmed that the dose due to Cl-36 which is dominant nuclide at groundwater scenario in the safety assessment is sensitive to radionuclide leaching rate from radioactive wastes, but the dose due to Nb-94 which is dominant nuclide at tunnel excavation scenario in the assessment is not sensitive to radionuclide leaching rate but to distribution coefficients of engineered barrier. (author)

  9. Behavior of calcium silicate in leaching process

    Institute of Scientific and Technical Information of China (English)

    刘桂华; 李小斌; 彭志宏; 周秋生

    2003-01-01

    Based on the thermodynamic calculation, the mole ratio of CaO to SiO2, temperature and A/S of bauxitehave a profound influence on the mole ratio of 2CaO @ SiO2 to CaO @ SiO2 in sinter. CaO @ SiO2 and β-2CaO @ SiO2appear stable in caustic solution but unstable in soda solution, and CaO @ SiO2 is more stable than β-2CaO @ SiO2 un-der the same leaching condition. Compared with the conventional sinter, the rate of alumina extraction of the newsinter is large and the secondary reaction is restricted in the leaching, which might be mainly due to the more contentof CaO @ SiO2 in sinter and better stability of CaO @ SiO2 in leaching.

  10. [Dynamic change of phosphorus leaching of neutral purple soil at different re-wetting rate].

    Science.gov (United States)

    Zhang, Si-Lan; Shi, Xiao-Jun; Guo, Tao

    2014-03-01

    Re-wetting was one of the most common forms of abiotic stresses experienced by soils. To investigate the effects of soil re-wetting rate on phosphorus (P) leaching and the relationship between soil microbial biomass carbon (MBC) and forms of P in leachate; five kinds of neutral purple soils of different fertilizer treatments were analyzed using simulating lab test at re-wetting rate of 0 h, 2 h, 4 h, 24 h and 48 h. The results showed that: (1) The lowest content of MBC appeared at the rate of 2 h during the soil re-wetting process, and the content of MBC increased with the reducing re-wetting rate. (2) Slower re-wetting helped to enhance soil microbial activity and the enhancement effect of organic fertilizer with NPK fertilizer (MNPK) was more significant. (3) The P leaching events of all fertilizer treatments occurred mainly at rapid re-wetting rates such as 0 h, 2 h, 4 h. Slower re-wetting was an important measure to prevent P leaching especially for the soils applied with chemical fertilizers, and it was of great significance in the field management of P. (4) Dissolved organic phosphorus (DOP) was the primary leaching part in leachate, and the variation range of ratio of total dissolved phosphorus (TDP) to total phosphorus (TP) and DOP to TP was 35.42%-85.99% and 29.74%-78.58% respectively. (5) With the reducing of re-wetting rate, significant negative correlation was observed between MBC and TP, TDP as well as DOP in the leachate (P < 0.05). To sum up, it was speculated that the P in soil leachate mainly came from soil microorganisms. PMID:24881404

  11. Identifying critical nitrogen application rate for maize yield and nitrate leaching in a Haplic Luvisol soil using the DNDC model.

    Science.gov (United States)

    Zhang, Yitao; Wang, Hongyuan; Liu, Shen; Lei, Qiuliang; Liu, Jian; He, Jianqiang; Zhai, Limei; Ren, Tianzhi; Liu, Hongbin

    2015-05-01

    Identification of critical nitrogen (N) application rate can provide management supports for ensuring grain yield and reducing amount of nitrate leaching to ground water. A five-year (2008-2012) field lysimeter (1 m × 2 m × 1.2 m) experiment with three N treatments (0, 180 and 240 kg Nha(-1)) was conducted to quantify maize yields and amount of nitrate leaching from a Haplic Luvisol soil in the North China Plain. The experimental data were used to calibrate and validate the process-based model of Denitrification-Decomposition (DNDC). After this, the model was used to simulate maize yield production and amount of nitrate leaching under a series of N application rates and to identify critical N application rate based on acceptable yield and amount of nitrate leaching for this cropping system. The results of model calibration and validation indicated that the model could correctly simulate maize yield and amount of nitrate leaching, with satisfactory values of RMSE-observation standard deviation ratio, model efficiency and determination coefficient. The model simulations confirmed the measurements that N application increased maize yield compared with the control, but the high N rate (240 kg Nha(-1)) did not produce more yield than the low one (120 kg Nha(-1)), and that the amount of nitrate leaching increased with increasing N application rate. The simulation results suggested that the optimal N application rate was in a range between 150 and 240 kg ha(-1), which would keep the amount of nitrate leaching below 18.4 kg NO₃(-)-Nha(-1) and meanwhile maintain acceptable maize yield above 9410 kg ha(-1). Furthermore, 180 kg Nha(-1) produced the highest yields (9837 kg ha(-1)) and comparatively lower amount of nitrate leaching (10.0 kg NO₃(-)-Nha(-1)). This study will provide a valuable reference for determining optimal N application rate (or range) in other crop systems and regions in China. PMID:25681775

  12. Identifying critical nitrogen application rate for maize yield and nitrate leaching in a Haplic Luvisol soil using the DNDC model.

    Science.gov (United States)

    Zhang, Yitao; Wang, Hongyuan; Liu, Shen; Lei, Qiuliang; Liu, Jian; He, Jianqiang; Zhai, Limei; Ren, Tianzhi; Liu, Hongbin

    2015-05-01

    Identification of critical nitrogen (N) application rate can provide management supports for ensuring grain yield and reducing amount of nitrate leaching to ground water. A five-year (2008-2012) field lysimeter (1 m × 2 m × 1.2 m) experiment with three N treatments (0, 180 and 240 kg Nha(-1)) was conducted to quantify maize yields and amount of nitrate leaching from a Haplic Luvisol soil in the North China Plain. The experimental data were used to calibrate and validate the process-based model of Denitrification-Decomposition (DNDC). After this, the model was used to simulate maize yield production and amount of nitrate leaching under a series of N application rates and to identify critical N application rate based on acceptable yield and amount of nitrate leaching for this cropping system. The results of model calibration and validation indicated that the model could correctly simulate maize yield and amount of nitrate leaching, with satisfactory values of RMSE-observation standard deviation ratio, model efficiency and determination coefficient. The model simulations confirmed the measurements that N application increased maize yield compared with the control, but the high N rate (240 kg Nha(-1)) did not produce more yield than the low one (120 kg Nha(-1)), and that the amount of nitrate leaching increased with increasing N application rate. The simulation results suggested that the optimal N application rate was in a range between 150 and 240 kg ha(-1), which would keep the amount of nitrate leaching below 18.4 kg NO₃(-)-Nha(-1) and meanwhile maintain acceptable maize yield above 9410 kg ha(-1). Furthermore, 180 kg Nha(-1) produced the highest yields (9837 kg ha(-1)) and comparatively lower amount of nitrate leaching (10.0 kg NO₃(-)-Nha(-1)). This study will provide a valuable reference for determining optimal N application rate (or range) in other crop systems and regions in China.

  13. Filtration and Leach Testing for PUREX Cladding Sludge and REDOX Cladding Sludge Actual Waste Sample Composites

    Energy Technology Data Exchange (ETDEWEB)

    Shimskey, Rick W.; Billing, Justin M.; Buck, Edgar C.; Casella, Amanda J.; Crum, Jarrod V.; Daniel, Richard C.; Draper, Kathryn E.; Edwards, Matthew K.; Hallen, Richard T.; Kozelisky, Anne E.; MacFarlan, Paul J.; Peterson, Reid A.; Swoboda, Robert G.

    2009-03-02

    of gibbsite, and its impact on filtration. The initial sample was diluted with a liquid simulant to simulate the receiving concentration of retrieved tank waste into the UFP2 vessel (< 10 wt% undissolved solids). Filtration testing was performed on the dilute waste sample and dewatered to a higher solids concentration. Filtration testing was then performed on the concentrated slurry. Afterwards, the slurry was caustic leached to remove aluminum present in the undissolved solid present in the waste. The leach was planned to simulate leaching conditions in the UFP2 vessel. During the leach, slurry supernate samples were collected to measure the dissolution rate of aluminum in the waste. After the slurry cooled down from the elevated leach temperature, the leach liquor was dewatered from the solids. The remaining slurry was rinsed and dewatered with caustic solutions to remove a majority of the dissolved aluminum from the leached slurry. The concentration of sodium hydroxide in the rinse solutions was high enough to maintain the solubility of the aluminum in the dewatered rinse solutions after dilution of the slurry supernate. Filtration tests were performed on the final slurry to compare to filtration performance before and after caustic leaching.

  14. Applying a statewide geospatial leaching tool for assessing soil vulnerability ratings for agrochemicals across the contiguous United States.

    Science.gov (United States)

    Ki, Seo Jin; Ray, Chittaranjan; Hantush, Mohamed M

    2015-06-15

    A large-scale leaching assessment tool not only illustrates soil (or groundwater) vulnerability in unmonitored areas, but also can identify areas of potential concern for agrochemical contamination. This study describes the methodology of how the statewide leaching tool in Hawaii modified recently for use with pesticides and volatile organic compounds can be extended to the national assessment of soil vulnerability ratings. For this study, the tool was updated by extending the soil and recharge maps to cover the lower 48 states in the United States (US). In addition, digital maps of annual pesticide use (at a national scale) as well as detailed soil properties and monthly recharge rates (at high spatial and temporal resolutions) were used to examine variations in the leaching (loads) of pesticides for the upper soil horizons. Results showed that the extended tool successfully delineated areas of high to low vulnerability to selected pesticides. The leaching potential was high for picloram, medium for simazine, and low to negligible for 2,4-D and glyphosate. The mass loadings of picloram moving below 0.5 m depth increased greatly in northwestern and central US that recorded its extensive use in agricultural crops. However, in addition to the amount of pesticide used, annual leaching load of atrazine was also affected by other factors that determined the intrinsic aquifer vulnerability such as soil and recharge properties. Spatial and temporal resolutions of digital maps had a great effect on the leaching potential of pesticides, requiring a trade-off between data availability and accuracy. Potential applications of this tool include the rapid, large-scale vulnerability assessments for emerging contaminants which are hard to quantify directly through vadose zone models due to lack of full environmental data.

  15. Caustics in dark matter haloes

    CERN Document Server

    Mohayaee, R; Mohayaee, Roya; Colombi, Stephane; Fort, Bernard; Gavazzi, Raphael; Shandarin, Sergei; Touma, Jihad

    2005-01-01

    Cold dark matter haloes are populated by high-density structures with sharply-peaked profiles known as caustics which have not yet been resolved by 3-dimensional numerical simulations. Here, we derive semi-analytic expressions for the density profiles near caustics in haloes which form by self-similar accretions of dark matter with infinitesimal velocity dispersion. A simple rescaling shows that these profiles are universal: they are valid for all caustics and irrespective of physical parameters of the halo. We derive the maximum density of the caustics and show that it depends on the velocity dispersion and the caustic location. Finally, we demonstrate that there can be a significant contribution to the emission measure from dark matter particle annihilation in the caustics.

  16. COMPILATION OF LABORATORY SCALE ALUMINUM WASH AND LEACH REPORT RESULTS

    Energy Technology Data Exchange (ETDEWEB)

    HARRINGTON SJ

    2011-01-06

    This report compiles and analyzes all known wash and caustic leach laboratory studies. As further data is produced, this report will be updated. Included are aluminum mineralogical analysis results as well as a summation of the wash and leach procedures and results. Of the 177 underground storage tanks at Hanford, information was only available for five individual double-shell tanks, forty-one individual single-shell tanks (e.g. thirty-nine 100 series and two 200 series tanks), and twelve grouped tank wastes. Seven of the individual single-shell tank studies provided data for the percent of aluminum removal as a function of time for various caustic concentrations and leaching temperatures. It was determined that in most cases increased leaching temperature, caustic concentration, and leaching time leads to increased dissolution of leachable aluminum solids.

  17. COMPILATION OF LABORATORY SCALE ALUMINUM WASH AND LEACH REPORT RESULTS

    International Nuclear Information System (INIS)

    This report compiles and analyzes all known wash and caustic leach laboratory studies. As further data is produced, this report will be updated. Included are aluminum mineralogical analysis results as well as a summation of the wash and leach procedures and results. Of the 177 underground storage tanks at Hanford, information was only available for five individual double-shell tanks, forty-one individual single-shell tanks (e.g. thirty-nine 100 series and two 200 series tanks), and twelve grouped tank wastes. Seven of the individual single-shell tank studies provided data for the percent of aluminum removal as a function of time for various caustic concentrations and leaching temperatures. It was determined that in most cases increased leaching temperature, caustic concentration, and leaching time leads to increased dissolution of leachable aluminum solids.

  18. Nitrogen Fertilizer Rate and Crop Management Effects on Nitrate Leaching from an Agricultural Field in Central Pennsylvania

    Directory of Open Access Journals (Sweden)

    Richard H. Fox

    2001-01-01

    Full Text Available Eighteen pan lysimeters were installed at a depth of 1.2 m in a Hagerstown silt loam soil in a corn field in central Pennsylvania in 1988. In 1995, wick lysimeters were also installed at 1.2 m depth in the same access pits. Treatments have included N fertilizer rates, use of manure, crop rotation (continuous corn, corn-soybean, alfalfa-corn, and tillage (chisel plow-disk, no-till. The leachate data were used to evaluate a number of nitrate leaching models. Some of the highlights of the 11 years of results include the following: 1 growing corn without organic N inputs at the economic optimum N rate (EON resulted in NO3–-N concentrations of 15 to 20 mg l-1 in leachate; 2 use of manure or previous alfalfa crop as partial source of N also resulted in 15 to 20 mg l-1 of NO3–-N in leachate below corn at EON; 3 NO3–-N concentration in leachate below alfalfa was approximately 4 mg l-1; 4 NO3–-N concentration in leachate below soybeans following corn was influenced by fertilizer N rate applied to corn; 5 the mass of NO3–-N leached below corn at the EON rate averaged 90 kg N ha-1 (approx. 40% of fertilizer N applied at EON; 6 wick lysimeters collected approximately 100% of leachate vs. 40–50% collected by pan lysimeters. Coefficients of variation of the collected leachate volumes for both lysimeter types were similar; 7 tillage did not markedly affect nitrate leaching losses; 8 tested leaching models could accurately predict leachate volumes and could be calibrated to match nitrate leaching losses in calibration years, but only one model (SOILN accurately predicted nitrate leaching losses in the majority of validation treatment years. Apparent problems with tested models: there was difficulty estimating sizes of organic N pools and their transformation rates, and the models either did not include a macropore flow component or did not handle macropore flow well.

  19. Evaluation of Foaming and Antifoam Effectiveness During the WTP Oxidative Leaching Process

    Energy Technology Data Exchange (ETDEWEB)

    Burket, P. R.; Jones, T. M.; White, T. L.; Crawford, C. L.; Calloway, T. B

    2005-10-11

    The River Protection Project-Waste Treatment Plant (RPP-WTP) requested Savannah River National Laboratory (SRNL) to conduct small-scale foaming and antifoam testing using a Hanford waste simulant subjected to air sparging during oxidative leaching. The foaminess of Hanford tank waste solutions was previously demonstrated by SRNL during WTP evaporator foaming studies and in small scale air sparger studies. The commercial antifoam, Dow Corning Q2-3183A was recommended to mitigate the foam in the evaporators and in vessel equipped with pulse jet mixers and air spargers. Currently, WTP is planning to use air spargers in the HLW Lag Storage Vessels (HLP-VSL-00027A/B), the Ultrafiltration Vessels (UFP-VSL-00002A&B), and the HLW Feed Blend Vessel (HLPVSL-00028) to assist the performance of the Pulse Jet Mixers (PJM). The previous air sparger antifoam studies conducted by SRNL researchers did not evaluate the hydrogen generation rate expected from antifoam additions or the effectiveness of the antifoam during caustic leaching or oxidative leaching. The fate of the various antifoam components and breakdown products in the WTP process under prototypic process conditions (temperature & radiation) was also not investigated. The effectiveness of the antifoam during caustic leaching, expected hydrogen generation rate associated with antifoam addition, and the fate of various antifoam components are being conducted under separate SRNL research tasks.

  20. Characterization, Washing, Leaching, and Filtration of C-104 Sludge

    Energy Technology Data Exchange (ETDEWEB)

    KP Brooks; PR Bredt; GR Golcar; SA Hartley; LK Jagoda; KG Rappe; MW Urie

    2000-06-09

    Approximately 1,400 g of wet Hanford Tank C-104 Sludge was evaluated by Battelle for the high-level waste (HLW) pretreatment processes of ultrafiltration, dilute caustic washing, and elevated-temperature caustic leaching. The filterability of diluted C-104 sludge was measured with a 0.1-{micro}m sintered metal Mott filter using a 24-inch-long, single-element, crossflow filtration system (cells unit filter [CUF]). While the filtrate was being recirculated prior to washing and leaching, a 6.9 wt% solids slurry was evaluated with a matrix of seven 1-hour conditions of varying trans-membrane pressure (30 to 70 psid) and axial velocity (9 to 15 ft/s). The filtrate flux and backpulse efficiency were determined for each condition. The slurry was concentrated to 23 wt% solids, a second matrix of six 1-hour conditions was performed, and data analogous to that recorded in the first matrix were obtained. The low-solids-concentration matrix produced filtrate flux rates that ranged from 0.038 to 0.083 gpm/ft{sup 2}. The high-solids-concentration matrix produced filtrate flux rates that ranged from 0.0095 to 0.0172 gpm/ft{sup 2}. In both cases, the optimum filtrate flux was at the highest axial velocity (15 ft/s) and transmembrane pressure had little effect. Nearly all of the measured filtrate fluxes were more than an order of magnitude greater than the required plant flux for C-104 of 0.00126 gpm/ft{sup 2}. In both matrices, the filtrate flux appeared to be proportional to axial velocity, and the permeability appeared to be inversely proportional to the trans-membrane pressure. The first test condition was repeated as the last test condition for each matrix. In both cases, there was a significant decrease in filtrate flux, indicating some filter fouling during the test matrix that could not be removed by backpulsing alone, although the backpulse number and duration were not optimized. Following testing of these two matrices, the material was washed within the CUF by

  1. Characterization, Washing, Leaching, and Filtration of C-104 Sludge

    International Nuclear Information System (INIS)

    Approximately 1,400 g of wet Hanford Tank C-104 Sludge was evaluated by Battelle for the high-level waste (HLW) pretreatment processes of ultrafiltration, dilute caustic washing, and elevated-temperature caustic leaching. The filterability of diluted C-104 sludge was measured with a 0.1-microm sintered metal Mott filter using a 24-inch-long, single-element, crossflow filtration system (cells unit filter [CUF]). While the filtrate was being recirculated prior to washing and leaching, a 6.9 wt% solids slurry was evaluated with a matrix of seven 1-hour conditions of varying trans-membrane pressure (30 to 70 psid) and axial velocity (9 to 15 ft/s). The filtrate flux and backpulse efficiency were determined for each condition. The slurry was concentrated to 23 wt% solids, a second matrix of six 1-hour conditions was performed, and data analogous to that recorded in the first matrix were obtained. The low-solids-concentration matrix produced filtrate flux rates that ranged from 0.038 to 0.083 gpm/ft2. The high-solids-concentration matrix produced filtrate flux rates that ranged from 0.0095 to 0.0172 gpm/ft2. In both cases, the optimum filtrate flux was at the highest axial velocity (15 ft/s) and transmembrane pressure had little effect. Nearly all of the measured filtrate fluxes were more than an order of magnitude greater than the required plant flux for C-104 of 0.00126 gpm/ft2. In both matrices, the filtrate flux appeared to be proportional to axial velocity, and the permeability appeared to be inversely proportional to the trans-membrane pressure. The first test condition was repeated as the last test condition for each matrix. In both cases, there was a significant decrease in filtrate flux, indicating some filter fouling during the test matrix that could not be removed by backpulsing alone, although the backpulse number and duration were not optimized. Following testing of these two matrices, the material was washed within the CUF by continuously adding

  2. Velocity peaks and caustic rings

    International Nuclear Information System (INIS)

    The late infall of cold dark matter onto an isolated galaxy produces flows with definite velocity vectors at any physical point in the galactic halo. It also produces caustic rings, which are places in space where the dark matter density is very large. The self-similar model of galactic halo formation predicts that the caustic ring radii an follow the approximate law an ≅ 1/n. Bumps in the rotation curves of NGC 3198 and of our own galaxy are interpreted as due to caustic rings of dark matter

  3. Microstructure and leach rates of apatite glass-ceramics as a host for Sr high-level liquid waste

    Science.gov (United States)

    He, Yong; Bao, Weimin; Song, Chongli

    2002-10-01

    An apatite glass-ceramic wasteform with 21 wt% SrO loading was fabricated for immobilizing Sr high-level liquid waste. The normalized leach rates of Sr, K, Mo, Al, P, Si are 6.9×10 -4, 1.09×10 -1, 2.7×10 -3, 3.22×10 -2, 2.84×10 -2, 3.26×10 -2 g/m 2 day, respectively. Component Fe in all leachates is not detectable in the 28-day static leaching test procedure in MCC-1. Instead of leaching, component Ca is adsorbed by testing samples. All the component Mo concentrates in the glass matrix of the well crystallized apatite glass-ceramics. For an apatite glass-ceramic wasteform, the optimum microstructure should be one in which poorly crystallized apatite crystallites distribute evenly in the glass phase. Perfect crystallization makes the crystal phase more stoichiometric and significantly changes the composition of the coexisting glass phase in the system, which, in our case, decreases the chemical stability of the apatite glass-ceramics.

  4. Causticizing for Black Liquor Gasifiers

    Energy Technology Data Exchange (ETDEWEB)

    Scott Sinquefeld; James Cantrell; Xiaoyan Zeng; Alan Ball; Jeff Empie

    2009-01-07

    The cost-benefit outlook of black liquor gasification (BLG) could be greatly improved if the smelt causticization step could be achieved in situ during the gasification step. Or, at a minimum, the increase in causticizing load associated with BLG could be mitigated. A number of chemistries have been proven successful during black liquor combustion. In this project, three in situ causticizing processes (titanate, manganate, and borate) were evaluated under conditions suitable for high temperature entrained flow BLG, and low temperature steam reforming of black liquor. The evaluation included both thermodynamic modeling and lab experimentation. Titanate and manganate were tested for complete direct causticizing (to thus eliminate the lime cycle), and borates were evaluated for partial causticizing (to mitigate the load increase associated with BLG). Criteria included high carbonate conversion, corresponding hydroxide recovery upon hydrolysis, non process element (NPE) removal, and economics. Of the six cases (three chemistries at two BLG conditions), only two were found to be industrially viable: titanates for complete causticizing during high temperature BLG, and borates for partial causticizing during high temperature BLG. These two cases were evaluated for integration into a gasification-based recovery island. The Larsen [28] BLG cost-benefit study was used as a reference case for economic forecasting (i.e. a 1500 tpd pulp mill using BLG and upgrading the lime cycle). By comparison, using the titanate direct causticizing process yielded a net present value (NPV) of $25M over the NPV of BLG with conventional lime cycle. Using the existing lime cycle plus borate autocausticizing for extra capacity yielded a NPV of $16M.

  5. The Influence of Zeolite Granular Size and Temperature for Waste Ceramicof Leached Rate

    International Nuclear Information System (INIS)

    The experiment was conducted by mixing, zeolite, water and uranium wastefor the ceramic monolite block. The parameters to be investigated were theeffect of zeolite granular of size -10/+20 - -100/+200 mesh and temperatureof 800 - 1200 oC. The conclusions that could be drawn from the research withthe best zeolite granular size of -80/+100 mesh and temperature of 1200 oC.The compound was leached in aquadest 22.76x10-3 - 10.74x10-3 gram cm-2day-1. (author)

  6. PEP Support Laboratory Leaching and Permeate Stability Tests

    Energy Technology Data Exchange (ETDEWEB)

    Russell, Renee L.; Peterson, Reid A.; Rinehart, Donald E.; Buchmiller, William C.

    2009-09-25

    Pacific Northwest National Laboratory (PNNL) has been tasked by Bechtel National Inc. (BNI) on the River Protection Project-Hanford Tank Waste Treatment and Immobilization Plant (RPP-WTP) project to perform research and development activities to resolve technical issues identified for the Pretreatment Facility (PTF). The Pretreatment Engineering Platform (PEP) was designed, constructed, and operated as part of a plan to respond to issue M12, "Undemonstrated Leaching Processes," of the External Flowsheet Review Team (EFRT) issue response plan.( ) The PEP is a 1/4.5-scale test platform designed to simulate the WTP pretreatment caustic leaching, oxidative leaching, ultrafiltration solids concentration, and slurry washing processes. The PEP replicates the WTP leaching processes using prototypic equipment and control strategies. A simplified flow diagram of the PEP system is shown in Figure 1.1. Two operating scenarios are currently being evaluated for the ultrafiltration process (UFP) and leaching operations. The first scenario has caustic leaching performed in the UFP-2 ultrafiltration feed vessels (i.e., vessel UFP-VSL-T02A in the PEP and vessels UFP-VSL-00002A and B in the WTP PTF). The second scenario has caustic leaching conducted in the UFP-1 ultrafiltration feed preparation vessels (i.e., vessels UFP-VSL-T01A and B in the PEP and vessels UFP-VSL-00001A and B in the WTP PTF). In both scenarios, 19-M sodium hydroxide solution (NaOH, caustic) is added to the waste slurry in the vessels to leach solid aluminum compounds (e.g., gibbsite, boehmite). Caustic addition is followed by a heating step that uses direct injection of steam to accelerate the leach process. Following the caustic leach, the vessel contents are cooled using vessel cooling jackets and/or external heat exchangers. The main difference between the two scenarios is that for leaching in UFP-VSL-T01A and B, the 19-M NaOH is added to un-concentrated waste slurry (3 to 8 wt% solids), while for leaching in

  7. Model simulation of solute leaching and its application for estimating the net rate of nitrate formation under field conditions

    Science.gov (United States)

    Otoma, Suehiro; Kuboi, Toru

    1985-12-01

    A model of the discrete type was built to describe unsteady infiltrations and redistributions of water and solutes in soil. The model was evaluated by comparing the measurements of the changes in chloride concentration in the field soil amended with sewage sludge with those obtained by simulation. The simulations showed that the amount of chloride adsorbed in the field was as small as 60% of that measured in the flask of the batch test, and that most of the chloride leached quickly through the upper zone of soil (0-20 cm) but stagnated in the lower zone (20-100 cm). The model was applied for estimating the daily net rate of nitrate formation. The estimation results indicated that the rate was accelerated remarkably by rainfall and abruptly slowed down soon after.

  8. Process for converting sodium nitrate-containing, caustic liquid radioactive wastes to solid insoluble products

    Science.gov (United States)

    Barney, Gary S.; Brownell, Lloyd E.

    1977-01-01

    A method for converting sodium nitrate-containing, caustic, radioactive wastes to a solid, relatively insoluble, thermally stable form is provided and comprises the steps of reacting powdered aluminum silicate clay, e.g., kaolin, bentonite, dickite, halloysite, pyrophyllite, etc., with the sodium nitrate-containing radioactive wastes which have a caustic concentration of about 3 to 7 M at a temperature of 30.degree. C to 100.degree. C to thereby entrap the dissolved radioactive salts in the aluminosilicate matrix. In one embodiment the sodium nitrate-containing, caustic, radioactive liquid waste, such as neutralized Purex-type waste, or salts or oxide produced by evaporation or calcination of these liquid wastes (e.g., anhydrous salt cake) is converted at a temperature within the range of 30.degree. C to 100.degree. C to the solid mineral form-cancrinite having an approximate chemical formula 2(NaAlSiO.sub.4) .sup.. xSalt.sup.. y H.sub.2 O with x = 0.52 and y = 0.68 when the entrapped salt is NaNO.sub.3. In another embodiment the sodium nitrate-containing, caustic, radioactive liquid is reacted with the powdered aluminum silicate clay at a temperature within the range of 30.degree. C to 100.degree. C, the resulting reaction product is air dried eitheras loose powder or molded shapes (e.g., bricks) and then fired at a temperature of at least 600.degree. C to form the solid mineral form-nepheline which has the approximate chemical formula of NaAlSiO.sub.4. The leach rate of the entrapped radioactive salts with distilled water is reduced essentially to that of the aluminosilicate lattice which is very low, e.g., in the range of 10.sup.-.sup.2 to 10.sup.-.sup.4 g/cm.sup.2 -- day for cancrinite and 10.sup.-.sup.3 to 10.sup.-.sup.5 g/cm.sup.2 -- day for nepheline.

  9. Immobilized waste leaching

    International Nuclear Information System (INIS)

    The main mechanism by which the immobilized radioactive materials can return to biosphere is the leaching due to the intrusion of water into the repositories. Some mathematical models and experiments utilized to evaluate the leaching rates in different immobilization matrices are described. (author)

  10. Sensitivity analysis of the leaching rate parameter in assessing the environmental risk of phosphogypsum application in sanitary landfills

    Energy Technology Data Exchange (ETDEWEB)

    Marchesi, Marcos Vinicius A.; Hama, Naruhiko; Jacomino, Vanusa M.F.; Ladeira, Ana Claudia Q.; Cota, Stela D.S., E-mail: mvmarchesi@hotmail.com, E-mail: sdsc@cdtn.br, E-mail: vmfj@cdtn.br, E-mail: ana.ladeira@cdtn.br, E-mail: naruhikohama@hotmail.com [Centro de Desenvolvimento da Tecnologia Nuclear (CDTN/CNEN-MG), Belo Horizonte, MG (Brazil)

    2013-07-01

    The attack with sulfuric acid to phosphate rock produces both phosphoric acid, basic raw material in the manufacture of fertilizers, as a by-product called phosphogypsum. Phosphogypsum is composed mostly of calcium sulfate dihydrated, but may have high levels of impurities from the phosphate rock matrix as a series of natural radionuclides, and heavy metals (e.g. Cd, Zn) and metalloids (e.g. , As and Se). Although it is used for agricultural purposes and more recently in construction, in Brazil the generation rate estimated at six million tons per year is much higher than the amount spent on existing alternatives, and therefore mostly deposited in piles in the same place production, causing thereby the risk of contamination of soil and water resources of the region and providing risk to human health. Taken into account the need to find alternative arrangements for phosphogypsum and reduce the impact generated by its contaminants, this study aims to analyze the sensitivity of the leaching rate parameter in the environmental risk evaluation of the application of phosphogypsum in landfills through mathematical modeling, where it is evaluated the concentration of heavy metals and radionuclides in the layer of the soil under the clay layer of the landfill.

  11. The Influence of Form and Rate on the Efficacy of Matrix-Based Fertilizers to Reduce Nutrient Leaching

    Directory of Open Access Journals (Sweden)

    James A. Entry

    2009-01-01

    Full Text Available We tested the efficacy of matrix-based fertilizers (MBFs to reduce NO3, NH4, and total phosphorus (TP leaching compared to Osmocote 14-14-14, a commercial slow release fertilizer (SRF in greenhouse column studies. The MBFs covered a range of inorganic N and P in compounds that are relatively loosely bound (MBF4 and more tightly bound compounds (MBF5 with A12(SO43⋅18H2O and/or Fe2(SO43⋅3H2O and with high ionic exchange compounds starch, chitosan, and lignin. When N and P are released, the chemicals containing these nutrients in the MBF bind N and P to an Al2(SO43⋅18H2O and/or Fe2(SO43⋅3H2O starch- chitosan- lignin matrix. SRF leachate contained a greater amount of NO3, NH4, DRP, and TP than leachate from MBF4 and MBF5 regardless of whether fertilizers were pellets, banded or broadcast, or fertilizer rate. St Augustine grass growing in soils receiving MBF4 and MBF5 had decreased shoot biomass by 49% to 56% and decreased total biomass by 33% to 46% respectively as grass receiving SRF. Although further greenhouse and field testing are necessary, results of this initial investigation are promising and with further development, testing, and rate calibration should be competitive with commercial fertilizers in environmentally sensitive markets.

  12. The Influence of Form and Rate on the Efficacy of Matrix-Based Fertilizers to Reduce Nutrient Leaching

    International Nuclear Information System (INIS)

    We tested the efficacy of matrix-based fertilizers (MBFs) to reduce NO3, NH4, and total phosphorus (TP) leaching compared to Osmocote 14-14-14, a commercial slow release fertilizer (SRF) in greenhouse column studies. The MBFs covered a range of inorganic N and P in compounds that are relatively loosely bound (MBF4) and more tightly bound compounds (MBF5) with Al2(SO4)3 18H2O and/or Fe2(SO4)3 3H2O and with high ionic exchange compounds starch, chitosan, and lignin. When N and P are released, the chemicals containing these nutrients in the MBF bind N and P to an Al2(SO4)3 18H2O and/or Fe2(SO4)3 3H2O starch- chitosan- lignin matrix. SRF leachate contained a greater amount of NO3, NH4, DRP, and TP than leachate from MBF4 and MBF5 regardless of whether fertilizers were pellets, banded or broadcast, or fertilizer rate. St Augustine grass growing in soils receiving MBF4 and MBF5 had decreased shoot biomass by 49% to 56% and decreased total biomass by 33% to 46% respectively as grass receiving SRF. Although further greenhouse and field testing are necessary, results of this initial investigation are promising and with further development, testing, and rate calibration should be competitive with commercial fertilizers in environmentally sensitive markets.

  13. Modeling of Boehmite Leaching from Actual Hanford High-Level Waste Samples

    International Nuclear Information System (INIS)

    The Department of Energy plans to vitrify approximately 60,000 metric tons of high level waste sludge from underground storage tanks at the Hanford Nuclear Reservation. To reduce the volume of high level waste requiring treatment, a goal has been set to remove about 90 percent of the aluminum, which comprises nearly 70 percent of the sludge. Aluminum in the form of gibbsite and sodium aluminate can be easily dissolved by washing the waste stream with caustic, but boehmite, which comprises nearly half of the total aluminum, is more resistant to caustic dissolution and requires higher treatment temperatures and hydroxide concentrations. In this work, the dissolution kinetics of aluminum species during caustic leaching of actual Hanford high level waste samples is examined. The experimental results are used to develop a shrinking core model that provides a basis for prediction of dissolution dynamics from known process temperature and hydroxide concentration. This model is further developed to include the effects of particle size polydispersity, which is found to strongly influence the rate of dissolution

  14. Stress corrosion cracking of duplex stainless steels in caustic solutions

    Science.gov (United States)

    Bhattacharya, Ananya

    susceptibility. Annealed and water quenched specimens were found to be immune to SCC in caustic environment. Aging treatment at 800°C gave rise to sigma and chi precipitates in the DSS. However, these sigma and chi precipitates, known to initiate cracking in DSS in chloride environment did not cause any cracking of DSS in caustic solutions. Aging of DSS at 475°C had resulted in '475°C embrittlement' and caused cracks to initiate in the ferrite phase. This was in contrast to the cracks initiating in the austenite phase in the as-received DSS. Alloy composition and microstructure of DSS as well as solution composition (dissolved ionic species) was also found to affect the electrochemical behavior and passivation of DSS which in turn plays a major role in stress corrosion crack initiation and propagation. Corrosion rates and SCC susceptibility of DSS was found to increase with addition of sulfide to caustic solutions. Corrosion films on DSS, characterized using XRD and X-ray photoelectron spectroscopy, indicated that the metal sulfide compounds were formed along with oxides at the metal surface in the presence of sulfide containing caustic environments. These metal sulfide containing passive films are unstable and hence breaks down under mechanical straining, leading to SCC initiations. The overall results from this study helped in understanding the mechanism of SCC in caustic solutions. Favorable slip systems in the austenite phase of DSS favors slip-induced local film damage thereby initiating a stress corrosion crack. Repeated film repassivation and breaking, followed by crack tip dissolution results in crack propagation in the austenite phase of DSS alloys. Result from this study will have a significant impact in terms of identifying the alloy compositions, fabrication processes, microstructures, and environmental conditions that may be avoided to mitigate corrosion and stress corrosion cracking of DSS in caustic solutions.

  15. Caustic stress corrosion cracking of austenitic stainless steels with thermal treatment(TT)

    International Nuclear Information System (INIS)

    This paper dealt with the effects of TT(Thermal Treatment) and nitrogen content on caustic stress corrosion cracking of austenitic stainless steels. Nitrogen content and grain size had affected on the caustic SCC resistance. Increasing nitrogen content, SCC resistance was increased due to the enhanced repassivation rate, but at high nitrogen content, the resistance was decreased because of the dual effects between mechanical and repassivation behavior. Regardless of nitrogen content, TT improved the caustic SCC resistance and this behavior was reviewed on the points of residual stress, grain size, and dislocation array

  16. Increased stocking rate and associated strategic dry-off decision rules reduced the amount of nitrate-N leached under grazing.

    Science.gov (United States)

    Roche, J R; Ledgard, S F; Sprosen, M S; Lindsey, S B; Penno, J W; Horan, B; Macdonald, K A

    2016-07-01

    The effect of intensive agricultural systems on the environment is of increasing global concern, and recent review articles have highlighted the need for sustainable intensification of food production. In grazing dairy systems, the leaching of nitrate-N (NO3-N) to groundwater is a primary environmental concern. A herd-level factor considered by many to be a key contributor to the amount of NO3-N leached from dairy pastures is stocking rate (SR), and some countries have imposed limits to reduce the risk of NO3-N loss to groundwater. The objective of the current experiment was to determine the effect of dairy cow SR on NO3-N leached in a grazing system that did not import feed from off-farm and had the same N fertilizer input. Five SR were evaluated (2.2, 2.7, 3.1, 3.7, and 4.3 cows/ha) in a completely randomized design (i.e., 2 replicates of each SR as independent farmlets) over 2 y. Pasture utilization, milk production/hectare, and days in milk/hectare increased with SR, but days in milk/cow and milk production/cow declined. The concentration of NO3-N in drainage water and the quantity of NO3-N leached/ha per year declined linearly with increasing SR, and the operating profit/kg NO3-N leached per ha increased. Higher SR was associated with fewer days in milk/cow, resulting in a reduction in estimated urine N excretion/cow (the main source of N leaching) during the climatically sensitive period for NO3-N leaching (i.e., late summer to winter). We hypothesized that the reduction in estimated urine N excretion per cow led to an increase in urinary N spread and reduced losses from urine patches. The results presented indicate that lowering SR may not reduce nitrate leaching and highlight the need for a full farm system-level analysis of any management change to determine its effect on productivity and environmental outcomes. PMID:27157574

  17. Increased stocking rate and associated strategic dry-off decision rules reduced the amount of nitrate-N leached under grazing.

    Science.gov (United States)

    Roche, J R; Ledgard, S F; Sprosen, M S; Lindsey, S B; Penno, J W; Horan, B; Macdonald, K A

    2016-07-01

    The effect of intensive agricultural systems on the environment is of increasing global concern, and recent review articles have highlighted the need for sustainable intensification of food production. In grazing dairy systems, the leaching of nitrate-N (NO3-N) to groundwater is a primary environmental concern. A herd-level factor considered by many to be a key contributor to the amount of NO3-N leached from dairy pastures is stocking rate (SR), and some countries have imposed limits to reduce the risk of NO3-N loss to groundwater. The objective of the current experiment was to determine the effect of dairy cow SR on NO3-N leached in a grazing system that did not import feed from off-farm and had the same N fertilizer input. Five SR were evaluated (2.2, 2.7, 3.1, 3.7, and 4.3 cows/ha) in a completely randomized design (i.e., 2 replicates of each SR as independent farmlets) over 2 y. Pasture utilization, milk production/hectare, and days in milk/hectare increased with SR, but days in milk/cow and milk production/cow declined. The concentration of NO3-N in drainage water and the quantity of NO3-N leached/ha per year declined linearly with increasing SR, and the operating profit/kg NO3-N leached per ha increased. Higher SR was associated with fewer days in milk/cow, resulting in a reduction in estimated urine N excretion/cow (the main source of N leaching) during the climatically sensitive period for NO3-N leaching (i.e., late summer to winter). We hypothesized that the reduction in estimated urine N excretion per cow led to an increase in urinary N spread and reduced losses from urine patches. The results presented indicate that lowering SR may not reduce nitrate leaching and highlight the need for a full farm system-level analysis of any management change to determine its effect on productivity and environmental outcomes.

  18. EFRT M12 Issue Resolution: Comparison of PEP and Bench-Scale Oxidative Leaching Results

    Energy Technology Data Exchange (ETDEWEB)

    Rapko, Brian M.; Brown, Christopher F.; Eslinger, Paul W.; Fountain, Matthew S.; Hausmann, Tom S.; Huckaby, James L.; Hanson, Brady D.; Kurath, Dean E.; Minette, Michael J.

    2009-08-14

    Pacific Northwest National Laboratory (PNNL) has been tasked by Bechtel National Inc. (BNI) on the River Protection Project-Hanford Tank Waste Treatment and Immobilization Plant (RPP-WTP) project to perform research and development activities to resolve technical issues identified for the Pretreatment Facility (PTF). The Pretreatment Engineering Platform (PEP) was designed and constructed and is to be operated as part of a plan to respond to issue M12, “Undemonstrated Leaching Processes.” The PEP is a 1/4.5-scale test platform designed to simulate the WTP pretreatment caustic leaching, oxidative leaching, ultrafiltration solids concentration, and slurry washing processes. The PEP replicates the WTP leaching processes using prototypic equipment and control strategies. The PEP also includes non-prototypic ancillary equipment to support the core processing. Two operating scenarios are currently being evaluated for the ultrafiltration process (UFP) and leaching operations. The first scenario has caustic leaching performed in the UFP-2 ultrafiltration feed vessels (i.e., vessel UFP-VSL-T02A in the PEP; and vessels UFP-VSL-00002A and B in the WTP PTF). The second scenario has caustic leaching conducted in the UFP-1 ultrafiltration feed preparation vessels (i.e., vessels UFP-VSL-T01A and B in the PEP; vessels UFP-VSL-00001A and B in the WTP PTF). In both scenarios, 19-M sodium hydroxide solution (NaOH, caustic) is added to the waste slurry in the vessels to dissolve solid aluminum compounds (e.g., gibbsite, boehmite). Caustic addition is followed by a heating step that uses direct steam injection to accelerate the leaching process. Following the caustic leach, the vessel contents are cooled using vessel cooling jackets and/or external heat exchangers. The main difference between the two scenarios is that for leaching in UFP1, the 19-M NaOH is added to un-concentrated waste slurry (3 to 8 wt% solids), while for leaching in UFP2, the slurry is concentrated to nominally

  19. 27 CFR 21.102 - Caustic soda, liquid.

    Science.gov (United States)

    2010-04-01

    ... 27 Alcohol, Tobacco Products and Firearms 1 2010-04-01 2010-04-01 false Caustic soda, liquid. 21....102 Caustic soda, liquid. (a) The liquid caustic soda may consist of either 50 percent or 73 percent...: Accurately weigh 2 grams of liquid caustic soda into a 100 ml volumetric flask, dissolve, and dilute to...

  20. On the degree of caustics of reflection

    CERN Document Server

    Josse, Alfrederic

    2012-01-01

    Given a point S and an irreducible algebraic curve C in P^2, we consider the caustic of reflection defined as the envelope of the reflected lines from the point S on the curve C. We identify this caustic with the Zariski closure of the image of C by a rational map. Thanks to a general fundamental lemma, we give a formula of the degree of the caustic of reflection in terms of multiplicity numbers of pro-branches of C. Our formula holds in the most general case. We also give some precisions about Pl\\"ucker formulas.

  1. Caustic addition system operability test procedure

    International Nuclear Information System (INIS)

    This test procedure provides instructions for performing operational testing of the major components of the 241-AN-107 Caustic Addition System by WHC and Kaiser personnel at the Rotating Equipment Shop run-in pit (Bldg. 272E)

  2. Caustic graphene plasmons with Kelvin angle

    CERN Document Server

    Shi, Xihang; Gao, Fei; Xu, Hongyi; Yang, Zhaoju; Zhang, Baile

    2015-01-01

    A century-long argument made by Lord Kelvin that all swimming objects have an effective Mach number of 3, corresponding to the Kelvin angle of 19.5 degree for ship waves, has been recently challenged with the conclusion that the Kelvin angle should gradually transit to the Mach angle as the ship velocity increases. Here we show that a similar phenomenon can happen for graphene plasmons. By analyzing the caustic wave pattern of graphene plasmons stimulated by a swift charged particle moving uniformly above graphene, we show that at low velocities of the charged particle, the caustics of graphene plasmons form the Kelvin angle. At large velocities of the particle, the caustics disappear and the effective semi-angle of the wave pattern approaches the Mach angle. Our study introduces caustic wave theory to the field of graphene plasmonics, and reveals a novel physical picture of graphene plasmon excitation during electron energy-loss spectroscopy measurement.

  3. Tunable caustic phenomena in electron wavefields

    Energy Technology Data Exchange (ETDEWEB)

    Tavabi, Amir Hossein, E-mail: a.tavabi@fz-juelich.de [Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons (ER-C) and Peter Grünberg Institute (PGI), Forschungszentrum Jülich, D-52425 Jülich (Germany); Migunov, Vadim; Dwyer, Christian; Dunin-Borkowski, Rafal E. [Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons (ER-C) and Peter Grünberg Institute (PGI), Forschungszentrum Jülich, D-52425 Jülich (Germany); Pozzi, Giulio [Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons (ER-C) and Peter Grünberg Institute (PGI), Forschungszentrum Jülich, D-52425 Jülich (Germany); Department of Physics and Astronomy, University of Bologna, Viale B. Pichat 6/2, 40127 Bologna (Italy)

    2015-10-15

    Novel caustic phenomena, which contain fold, butterfly and elliptic umbilic catastrophes, are observed in defocused images of two approximately collinear oppositely biased metallic tips in a transmission electron microscope. The observed patterns depend sensitively on defocus, on the applied voltage between the tips and on their separation and lateral offset. Their main features are interpreted on the basis of a projected electrostatic potential model for the electron-optical phase shift. - Highlights: • Electron-optical caustics are observed in defocused images of biased metallic tips. • The caustics depend on defocus, on the bias between the tips and on their separation. • The setup offers the flexibility to study a wide variety of caustic phenomena.

  4. The Influence of Form and Rate on the Efficacy of Matrix-Based Fertilizers to Reduce Nutrient Leaching

    OpenAIRE

    James A. Entry; Sojka, R.E

    2009-01-01

    We tested the efficacy of matrix-based fertilizers (MBFs) to reduce N O 3 , N H 4 , and total phosphorus (TP) leaching compared to Osmocote 14-14-14, a commercial slow release fertilizer (SRF) in greenhouse column studies. The MBFs covered a range of inorganic N and P in compounds that are relatively loosely bound (MBF4) and more tightly bound compounds (MBF5) with A 1 2 ( S O 4 ) 3 ⋅ 1 8 H 2 O and/or F e 2 ( S O 4 ) 3 ⋅ 3 H 2 O and with high ionic exchange compounds starch, chitosan, and lig...

  5. A methodology for evaluating biocide release rate, surface roughness and leach layer formation in a TBT-free, self-polishing antifouling coating.

    Science.gov (United States)

    Howell, Dickon; Behrends, Brigitte

    2006-01-01

    Due to the forthcoming IMO ban on the use of tributyltin (TBT) antifouling paints, a new generation of TBT-free coatings has been developed that typically contain cuprous oxide and an organic co-biocide. Accurate and reproducible test methods are needed to evaluate the performance and environmental impact of these new coatings. This study investigated a methodology for evaluating TBT-free, AF coatings containing cuprous oxide. A commercially available AF coating underwent rotary immersion testing at 0, 0.51 and 2.05 m s-1. Scanning electron microscopy (SEM) and energy dispersive x-ray (EDX) analysis were used to assess leach layer formation, percentage cuprous oxide by weight and particle size distribution (PSD). Biocide release rates and surface roughness were also measured. An increase in rotary speed caused a spike in Cu2+ release rate after which the release rate stabilised to previous levels. An increase in leach layer thickness was also observed after the rotary speed increase. A model is suggested to account for the observations. PMID:17110354

  6. ANALYSIS ON INFLUENCE REGULARITY OF THE AMMONIA-AMMONIUM LEACHING SYSTEM ON LEACHING RATE OF COPPER%不同氨-铵浸出体系对氧化铜矿铜浸出率影响规律的研究

    Institute of Scientific and Technical Information of China (English)

    毛莹博; 方建军; 文娅; 赵文娟; 王珊; 魏志聪

    2012-01-01

    In this paper, through a series of experiment studies about the different ammonia-ammonium coupling of leaching system for the effect of copper oxide ore leaching, a significant influence sequence of the different ammonia-ammonium coupling of leaching system on the leaching rate of copper is determined as following : ammonia-ammonium carbamate > ammonia-ammonium carbonate > ammonia-ammonium chloride > ammonia-ammonium fluoride > ammonia-ammonium bicarbonate > ammonia-ammonium sulfate. The ammonia-ammonium carbamate leaching system is adopted as the experiment study of high calcium and magnesium, low grade and argillaceous copper oxide ore in Xinjiang Water, and the copper leaching rate is as high as 85. 25% .%通过不同氨-铵浸出体系对氧化铜矿浸出影响的试验研究,确定了不同氨-铵浸出体系对铜浸出率的显著性影响顺序是:氨-氨基甲酸铵>氨-碳酸铵>氨-氯化铵>氨-氟化铵>氨-碳酸氢铵>氨-硫酸铵.采用氨-氨基甲酸铵浸出体系对新疆滴水高钙镁低品位泥质氧化铜矿进行浸出试验,铜浸出率高达85.25%.

  7. Bacteria heap leaching test of a uranium ore

    International Nuclear Information System (INIS)

    Column bioleaching test of a uranium ore was carried out. The optimum acidity, spraying intensity, spray-pause time ratio were determined. The potential, Fe and U concentrations in the leaching process were investigated. The effect of bacteria column leaching was compared with that of acid column leaching. The results show that bacteria column leaching can shorten leaching cycle, and the leaching rate of uranium increases by 9.7%. (authors)

  8. Leaching of Zinc Sulfide by Thiobacillus ferrooxidans: Bacterial Oxidation of the Sulfur Product Layer Increases the Rate of Zinc Sulfide Dissolution at High Concentrations of Ferrous Ions

    OpenAIRE

    Fowler, T. A.; Crundwell, F. K.

    1999-01-01

    This paper reports the results of leaching experiments conducted with and without Thiobacillus ferrooxidans at the same conditions in solution. The extent of leaching of ZnS with bacteria is significantly higher than that without bacteria at high concentrations of ferrous ions. A porous layer of elemental sulfur is present on the surfaces of the chemically leached particles, while no sulfur is present on the surfaces of the bacterially leached particles. The analysis of the data using the shr...

  9. Probing dark matter caustics with weak lensing

    CERN Document Server

    Gavazzi, R; Fort, B; Gavazzi, Raphael; Mohayaee, Roya; Fort, Bernard

    2006-01-01

    Caustics are high-density structures that form frequently in collisionless media. Under self-gravity, cold dark matter flows focus onto caustics which are yet to be resolved in numerical simulations and or observed in the real world. If detected, caustics would provide a strong evidence for dark matter and would rule out alternative models such as those with modified dynamics. Here, we demonstrate how they might be observed in the weak lensing data. We evaluate the shear distortion and show that its radial profile is marked by a characteristic sawtooth pattern due to the caustics in dark matter haloes that form by selfsimilar accretion. We discuss the observational complications, mainly due to the poor knowledge of the virial radii of the haloes and demonstrate that a superposition of about 600 cluster-size haloes would give a signal-to-noise ratio which is sufficiently large for the detection of caustics with ground-based observations. This number is reduced to 200 for space-based observations. These bounds ...

  10. Line Caustic Microlensing and Limb Darkening

    CERN Document Server

    Rhie, S H; Rhie, Sun Hong; Bennett, David P.

    1999-01-01

    In a line caustic crossing microlensing event, the caustic line moving across the surface of the source star provides a direct method to measure the integrated luminosity profile of the star. Combined with the enormous brightening at the caustic crossings, microlensing offers a promising tool for studying stellar luminosity profiles. We derive the amplification behavior of the two extra images that become partial images conjoined across the critical curve at a line caustic crossing. We identify the multiplicative factors that depend on the caustic crossing point and the relative size of the star, and the shape function that depends on the stellar luminosity profile. We examine the analytic limb-darkening models -- linear, square root, and square -- using the analytic form of the shape function. We find that the microlensing lightcurves must be determined to an accuracy of better than 0.3-0.8% in order to be able to determine the linear limb-darkening parameter $c_1$ with precision of binaries as reported by P...

  11. Plutonium Speciation in Support of Oxidative-Leaching Demonstration Test

    Energy Technology Data Exchange (ETDEWEB)

    Sinkov, Sergey I.

    2007-10-31

    Bechtel National, Inc. (BNI) is evaluating the plutonium speciation in caustic solutions that reasonably represent the process streams from the oxidative-leaching demonstration test. Battelle—Pacific Northwest Division (PNWD) was contracted to develop a spectrophotometric method to measure plutonium speciation at submicromolar (< 10-6 M) concentrations in alkaline solutions in the presence of chromate and carbonate. Data obtained from the testing will be used to identify the oxidation state of Pu(IV), Pu(V), and Pu(VI) species, which potentially could exist in caustic leachates. Work was initially conducted under contract number 24590-101-TSA-W000-00004 satisfying the needs defined in Appendix C of the Research and Technology Plan TSS A-219 to evaluate the speciation of chromium, plutonium, and manganese before and after oxidative leaching. In February 2007, the contract mechanism was switched to Pacific Northwest National Laboratory (PNNL) Operating Contract MOA: 24590-QL-HC9-WA49-00001.

  12. Scintillation Caustics in Planetary Occultation Light Curves

    CERN Document Server

    Cooray, A R; Cooray, Asantha R.

    2003-01-01

    We revisit the GSC5249-01240 light curve obtained during its occultation by Saturn's North polar region. In addition to refractive scintillations, the power spectrum of intensity fluctuations shows an enhancement of power between refractive and diffractive regimes. We identify this excess power as due to high amplitude spikes in the light curve and suggest that these spikes are due to caustics associated with ray crossing situations. The flux variation in individual spikes follows the expected caustic behavior, including diffraction fringes which we have observed for the first time in a planetary occultation light curve. The presence of caustics in scintillation light curves require an inner scale cut off to the power spectrum of underlying density fluctuations associated with turbulence. Another possibility is the presence of gravity waves in the atmosphere. While occultation light curves previously showed the existence of refractive scintillations, a combination of small projected stellar size and a low rel...

  13. Electrochemical generation of fentons reagent to treat spent caustic wastewater

    International Nuclear Information System (INIS)

    An important wastewater stream from oil refineries is the spent caustic. Caustic solutions are used as scrubbing agent during the desulphurization process to eliminate sulphur an mercaptans from oil and gasses. Spent caustic is classified as DOO3 (reactive sulphide) hazardous waste under the US Resource Conservation and Recovery Act (RCRA). (Author)

  14. Influencing factors of pyrite leaching in germ-free system

    Institute of Scientific and Technical Information of China (English)

    OU Le-ming; HE Rong-quan; FENG Qi-ming

    2007-01-01

    The effect of mineral particle size,pulp potential and category of oxidant on pyrite leaching was studied.The results show that a smaller mineral particle size leads to a higher leaching rate of pyrite, and the optimum result with pyrite leaching rate of 2.92% is obtained when mineral particle size is less than 0.037 1/mm.The pulp potential reflects the leaching process. The increase of pulp potential can improve pyrite leaching. The leaching rate and velocity of pyrite can be enhanced rapidly by adding strong oxidant. The kind and the method of adding oxidant have important effect on the pyrite leaching. Appropriate concentration of Fe3+ can enhance pyrite leaching but the precipitation generated by high concentration of ferric ion covers the surface of pyrites and prevents the leaching process.The leaching rate increases with the constant addition of H2O2.

  15. Rendering Caustics on Non-Lambertian Surfaces

    DEFF Research Database (Denmark)

    Jensen, Henrik Wann

    1997-01-01

    This paper presents a new technique for rendering caustics on non-Lambertian surfaces. The method is based on an extension of the photon map which removes previous restrictions limiting the usage to Lambertian surfaces. We add information about the incoming direction to the photons and this allow...

  16. Effects of biochar on the contents of potassium and phosphorus,and their leaching rates in red soil under simulated leaching condition%淋溶条件下生物质炭对红壤中钾和磷含量及其淋出率的影响

    Institute of Scientific and Technical Information of China (English)

    朱盼; 应介官; 彭抒昂; 姜存仓

    2016-01-01

    采用室内模拟降水的方法,在未施肥红壤和施肥红壤中添加不同用量的生物质炭(0%、1%、2%和3%),分析在淋溶条件下生物质炭对土壤速效钾、速效磷含量及其淋出量的影响.结果表明:随着生物质炭用量的增加,红壤中速效钾和速效磷含量均显著提高,但淋洗液中总钾量和总磷量并没有显著增加;在未施肥土壤中,0%、1%、2%和3%生物质炭处理的钾淋出率分别为53.6%、14.3%、9.1%和7.5%,磷淋出率分别为88.8%、23.5%、16.3%和7.8%;在施肥土壤中,磷的淋出率随生物质炭用量的增加而减少,由24.1%降至7.2%;而钾淋出率受生物质炭用量的影响相对较小.在淋溶条件下,添加3%生物质炭可使未施肥土壤速效钾降幅由9.8%减少至0.3%,使施肥土壤速效钾降幅由10.8%减少至0.5%,但经生物质炭处理的未施肥和施肥土壤的速效磷含量在淋溶后下降更为明显.上述结果表明,生物质炭不仅能使土壤中速效钾和速效磷含量提高,且生物质炭有较强的养分保持能力,能够减少土壤中钾和磷的淋出率.%Summary Phosphorus(P)and potassium(K)are the major essential macronutrients required for the biological growth and development of crop.As the mineral resource reserve declined for both P and K,the increasing demand for phosphorus-potassium fertilizer from global food production caused imbalance between supply and demand.As a result,the cost of agricultural production increased,and economic benefits reduced,along with increasing environmental risks.In China,synchronization between rainfall and temperature is common in red soil area,with strong soil leaching, and phosphorus and potassium nutrients are easy to lose, thus excessive application of fertilizer is necessary.Therefore,investigation on improvement of use efficiency and reduction of leaching rate for K and P will have great economic significance on agricultural production,help maintaining good

  17. DEVELOPMENT OF A KINETIC MODEL OF BOEHMITE DISSOLUTION IN CAUSTIC SOLUTIONS APPLIED TO OPTIMIZE HANFORD WASTE PROCESSING

    Energy Technology Data Exchange (ETDEWEB)

    DISSELKAMP RS

    2011-01-06

    Boehmite (e.g., aluminum oxyhydroxide) is a major non-radioactive component in Hanford and Savannah River nuclear tank waste sludge. Boehmite dissolution from sludge using caustic at elevated temperatures is being planned at Hanford to minimize the mass of material disposed of as high-level waste (HLW) during operation of the Waste Treatment Plant (WTP). To more thoroughly understand the chemistry of this dissolution process, we have developed an empirical kinetic model for aluminate production due to boehmite dissolution. Application of this model to Hanford tank wastes would allow predictability and optimization of the caustic leaching of aluminum solids, potentially yielding significant improvements to overall processing time, disposal cost, and schedule. This report presents an empirical kinetic model that can be used to estimate the aluminate production from the leaching of boehmite in Hanford waste as a function of the following parameters: (1) hydroxide concentration; (2) temperature; (3) specific surface area of boehmite; (4) initial soluble aluminate plus gibbsite present in waste; (5) concentration of boehmite in the waste; and (6) (pre-fit) Arrhenius kinetic parameters. The model was fit to laboratory, non-radioactive (e.g. 'simulant boehmite') leaching results, providing best-fit values of the Arrhenius A-factor, A, and apparent activation energy, E{sub A}, of A = 5.0 x 10{sup 12} hour{sup -1} and E{sub A} = 90 kJ/mole. These parameters were then used to predict boehmite leaching behavior observed in previously reported actual waste leaching studies. Acceptable aluminate versus leaching time profiles were predicted for waste leaching data from both Hanford and Savannah River site studies.

  18. DEVELOPMENT OF A KINETIC MODEL OF BOEHMITE DISSOLUTION IN CAUSTIC SOLUTIONS APPLIED TO OPTIMIZE HANFORD WASTE PROCESSING

    International Nuclear Information System (INIS)

    Boehmite (e.g., aluminum oxyhydroxide) is a major non-radioactive component in Hanford and Savannah River nuclear tank waste sludge. Boehmite dissolution from sludge using caustic at elevated temperatures is being planned at Hanford to minimize the mass of material disposed of as high-level waste (HLW) during operation of the Waste Treatment Plant (WTP). To more thoroughly understand the chemistry of this dissolution process, we have developed an empirical kinetic model for aluminate production due to boehmite dissolution. Application of this model to Hanford tank wastes would allow predictability and optimization of the caustic leaching of aluminum solids, potentially yielding significant improvements to overall processing time, disposal cost, and schedule. This report presents an empirical kinetic model that can be used to estimate the aluminate production from the leaching of boehmite in Hanford waste as a function of the following parameters: (1) hydroxide concentration; (2) temperature; (3) specific surface area of boehmite; (4) initial soluble aluminate plus gibbsite present in waste; (5) concentration of boehmite in the waste; and (6) (pre-fit) Arrhenius kinetic parameters. The model was fit to laboratory, non-radioactive (e.g. 'simulant boehmite') leaching results, providing best-fit values of the Arrhenius A-factor, A, and apparent activation energy, EA, of A = 5.0 x 1012 hour-1 and EA = 90 kJ/mole. These parameters were then used to predict boehmite leaching behavior observed in previously reported actual waste leaching studies. Acceptable aluminate versus leaching time profiles were predicted for waste leaching data from both Hanford and Savannah River site studies.

  19. Epidemiology and prevention of caustic ingestion in children

    DEFF Research Database (Denmark)

    Christesen, H B

    1994-01-01

    A total of 102 children less than 16 years of age admitted for caustic ingestion in the period 1976-1991 were registered. The annual incidence rate of hospitalization was 10.8:100,000 for the city of Aarhus, Denmark. Esophageal burns occurred with a frequency of 5.0:100,000 per year. Ninety......-four percent of the children were less than 5 years old. For this age group, the incidence rates of admission and esophageal burns were 34.6:100,000 and 15.8:100,000, respectively. All ingestions were accidental. The incidence rates of esophageal burns in children 0-4 years old (p = 0.019) decreased...

  20. Interaction of aqueous caustic with acidic oils

    Energy Technology Data Exchange (ETDEWEB)

    Chiwetelu, C.I.; Hornof, V.; Neale, G.H. (Univ. of Ottawa, Ottawa, ON (Canada))

    High content of native carboxylic acids make heavy oils acidic. It is generally accepted that these acids react with caustic reagents present in floodwater, resulting in the in-situ formation of surface active soap anions. When these adsorb at the oil-water interface, they can drastically lower the interfacial tension to the point where residual oil is mobilized. The most intriguing aspect of these acid/caustic interactions is the dynamic nature of the interfacial tension. Given a sufficiently long time, the dynamic tension would attain an equilibrium state. Measurements were made of the equilibrium interfacial tensions of acidified oleic phases contacted with a wide range of caustic concentrations in the aqueous phase. A novel measurement technique (photomicropendography) was used, and data analysis was carried out by nonlinear regression. The present approach utilizes pre-selected fatty acids in a defined oleic phase, enabling quantification of relevant model parameters and facilitating evaluation of key variables influencing interfacial activity. The acid ionization constant and the equilibrium constant governing the formation of inactive soap species were found to be the most important parameters for systems of oleic and lauric acids dissolved in hexadecane. Regression analysis showed that the acid dissociation constant (pKa) of oleic acid ranged from 6.2 to 6.9 and was dependent on the working acid concentration. For lauric acid, the pKa values were in the range of 9 to 11 depending on the caustic concentration of the aqueous phase. Species aggregation in both the oleic and aqueous phases is mostly responsible for the variations in pKa values. 30 refs., 10 figs., 4 tabs.

  1. In Situ Causticizing for Black Liquor Gasification

    Energy Technology Data Exchange (ETDEWEB)

    Scott Alan Sinquefield

    2005-10-01

    Black liquor gasification offers a number of attractive incentives to replace Tomlinson boilers but it also leads to an increase in the causticizing load. Reasons for this have been described in previous reports (FY04 ERC, et.al.). The chemistries have also been covered but will be reviewed here briefly. Experimental results of the causticizing reactions with black liquor are presented here. Results of the modeling work were presented in detail in the Phase 1 report. They are included in Table 2 for comparison but will not be discussed in detail. The causticizing agents were added to black liquor in the ratios shown in Table 1, mixed, and then spray-dried. The mixture ratios (doping levels) reflect amount calculated from the stoichiometry above to achieve specified conversions shown in the table. The solids were sieved to 63-90 microns for use in the entrained flow reactors. The firing conditions are shown in Table 2. Pictures and descriptions of the reactors can be found in the Phase 1 annual report. Following gasification, the solids (char) was collected and analyzed by coulometric titration (for carbonate and total carbon), and by inductively coupled plasma emission spectroscopy (ICP) for a wide array of metals.

  2. Analysis of factors affecting the effect of stope leaching

    International Nuclear Information System (INIS)

    The industrial test and industrial trial production of stope leaching were carried out at Taoshan orefield of Dabu deposit. The results of test and trial production showed obvious differences in leaching rate and leaching time. Compared with industrial trial production of stope leaching, the leaching rate of industrial test was higher, and leaching time was shorter. It was considered that the blasting method and liquid arrangement were the main factors affecting the leaching rate and leaching time according to analysis. So we put forward the following suggestions: the technique of deep hole slicing tight-face blasting was used to reduce the yield of lump ores, the effective liquid arrangement methods were adopted to make the lixiviant infiltrating throughout whole ore heap, and bacterial leaching was introduced. (authors)

  3. Spent LWR fuel leach tests: Waste Isolation Safety Assessment program

    International Nuclear Information System (INIS)

    Spent light-water-reactor (LWR) fuels with burnups of 54.5, 28 and 9 MWd/kgU were leach-tested in deionized water at 250C. Fuel burnup has no apparent effect on the calculated leach rates based upon the behavior of 137Cs and 239+240Pu. A leach test of 54.5 MWd/kgU spent fuel in synthetic sea brine showed that the cesium-based leach rate is lower in sea brine than in deionized water. A rise in the leach rate was observed after approximately 600 d of cumulative leaching. During the rise, the leach rate for all the measured radionuclides become nearly equal. Evidence suggests that exposure of new surfaces to the leachant may cause the increase. As a result, experimental work to study leaching mechanisms of spent fuel has been initiated. 22 figures

  4. Effect of Heat Treatment on Corrosion and Stress Corrosion Cracking of S32205 Duplex Stainless Steel in Caustic Solution

    Science.gov (United States)

    Bhattacharya, Ananya; Singh, Preet M.

    2009-06-01

    Duplex stainless steels (DSSs) have generally performed very well in caustic environments. However, some corrosion and stress corrosion cracking (SCC) of DSSs have been reported in different pulp mill environments employing caustic solutions. Studies have shown that the corrosion and SCC susceptibility of DSSs depend on the alloy composition and microstructure of the steel. In this study, the effect of a sulfide-containing caustic environment (pulping liquor) and material properties (DSS alloy composition and microstructure) on the corrosion and SCC of DSSs was evaluated. During metal fabrication processes, localized areas of DSSs may be exposed to different temperatures and cooling rates, which may lead to changes in the microstructure in these regions. This change in microstructure, in turn, may affect the general and localized corrosion or SCC susceptibility of the affected area as compared to the rest of the metal. Hence, the effect of different annealing and aging temperatures as well as cooling rates on the microstructure and corrosion behavior of S32205 DSSs in caustic environment was evaluated. The results showed that changes in the microstructure of S32205 DSSs due to selected heat treatments did not have a significant effect on the general corrosion susceptibility of the steel in caustic environment, but its SCC susceptibility varied with changes in microstructures.

  5. Test report - caustic addition system operability test procedure

    International Nuclear Information System (INIS)

    This Operability Test Report documents the test results of test procedure WHC-SD-WM-OTP-167 ''Caustic Addition System Operability Test Procedure''. The Objective of the test was to verify the operability of the 241-AN-107 Caustic Addition System. The objective of the test was met

  6. 钒渣钙化焙烧参数对钒浸出率的影响%Effects of Vanadium-containing Slag Calcium Roasting Conditions on Leaching Rate of Vanadium

    Institute of Scientific and Technical Information of China (English)

    李晓军; 张润平; 谢兵

    2012-01-01

    在分析钒渣(V2O3 8.07%)钙化焙烧过程反应机理的基础上,采用钙化焙烧-酸浸法研究了钙化焙烧过程中CaO/V2O3(质最比)、焙烧温度、焙烧时间对钒浸出率的影响.结果表明,焙烧温度在600~900℃之间时,V2O5等钒氧化物可与CaO发生反应,形成以CaV2O6,Ca3V2O8,CaV3O7为主的钒酸钙.当CaO/V2O3由0.48提高到约1.125时,钒浸出率由55.3%提高到69.2%,当CaO/V2O3>1.125时,钒浸出率开始下降.焙烧温度由750℃提高到825℃时,钒浸出率由56.3%提高到69.7%,温度进一步升高,物料开始烧结,浸出率逐渐下降.随焙烧时间延长,钒浸出率逐渐提高,2h后达最大;时间继续增加,钒浸出率会因物料间发生二次反应而下降.%Based on the analysis of reaction mechanism of vanadium-containing slag (V2O3 8.07%) calcium roasting process, the effects of various factors on vanadium leaching rate were investigated by means of calcium roasting coupled with acid leaching. The results showed that various calcium vanadates namely CaV2O6, Ca3V2O8, CaV3O7 would form between V2O5 and CaO at 600~900 ℃. The acid leaching of roasted slag indicated that the mass ratio of CaO to V2O3 in the roasted slag played an important role in the roasting process. Vanadium leaching rate increased from 55.3% to 69.2% when the ratio was from 0.48 to 1.125, while the rate decreased when the ratio exceeded 1.125. When the roasting temperature increased from 750 to 825 ℃, the leaching rate from 56.3% to 69.7%. However, the slag roasted the temperature higher than 825 ℃ lead to the decrease of leaching rate. Vanadium leaching rate increased with the roasting time. The maximum rate was achieved when the roasting time was 2 h. With longer roasting time, the slag reacted further, leading to the decrease of vanadium leaching rate.

  7. Mill Integration-Pulping, Stream Reforming and Direct Causticization for Black Liquor Recovery

    Energy Technology Data Exchange (ETDEWEB)

    Adriaan van Heiningen

    2007-06-30

    MTCI/StoneChem developed a steam reforming, fluidized bed gasification technology for biomass. DOE supported the demonstration of this technology for gasification of spent wood pulping liquor (or 'black liquor') at Georgia-Pacific's Big Island, Virginia mill. The present pre-commercial R&D project addressed the opportunities as well as identified negative aspects when the MTCI/StoneChem gasification technology is integrated in a pulp mill production facility. The opportunities arise because black liquor gasification produces sulfur (as H{sub 2}S) and sodium (as Na{sub 2}CO{sub 3}) in separate streams which may be used beneficially for improved pulp yield and properties. The negative aspect of kraft black liquor gasification is that the amount of Na{sub 2}CO{sub 3} which must be converted to NaOH (the so called causticizing requirement) is increased. This arises because sulfur is released as Na{sub 2}S during conventional kraft black liquor recovery, while during gasification the sodium associated Na{sub 2}S is partly or fully converted to Na{sub 2}CO{sub 3}. The causticizing requirement can be eliminated by including a TiO{sub 2} based cyclic process called direct causticization. In this process black liquor is gasified in the presence of (low sodium content) titanates which convert Na{sub 2}CO{sub 3} to (high sodium content) titanates. NaOH is formed when contacting the latter titanates with water, thereby eliminating the causticizing requirement entirely. The leached and low sodium titanates are returned to the gasification process. The project team comprised the University of Maine (UM), North Carolina State University (NCSU) and MTCI/ThermoChem. NCSU and MTCI are subcontractors to UM. The principal organization for the contract is UM. NCSU investigated the techno-economics of using advanced pulping techniques which fully utilize the unique cooking liquors produced by steam reforming of black liquor (Task 1). UM studied the kinetics and

  8. Kinetic study on pressure leaching of high iron sphalerite concentrate

    Institute of Scientific and Technical Information of China (English)

    XIE Ke-qiang; YANG Xian-wan; WANG Ji-kun; YAN Jiang-feng; SHEN Qing-feng

    2007-01-01

    The kinetics of pressure leaching high iron sphalerite concentrate was studied. The effects of agitation rate, temperature, oxygen partial pressure, initial acid concentration, particle size, iron content in the concentrate and concentration of Fe2+ added into the solution on the leaching rate of zinc were examined. The experiment results indicate that if the agitation rate is greater than 600 r/min, its influence on Zn leaching rate is not substantial. A suitable rise in temperature can facilitate the leaching reaction, and the temperature should be controlled at 140-150 ℃. The increase trend of Zn leaching rate becomes slow when pressure is greater than 1.2 MPa, so the pressure is controlled at 1.2-1.4 MPa. Under the conditions of this study, Zn leaching rate decreases with a rise in the initial sulfuric acid concentration; and Zn leaching rate increases with a rise of iron content in the concentrate and Fe2+ concentration in the solution. Moreover, the experiment demonstrates that the leaching process follows the surface chemical reaction control kinetic law of "shrinking of unreacted core". The activation energy for pressure leaching high iron sphalerite concentrate is calculated, and a mathematical model for this pressure leaching is obtained. The model is promising to guide the practical operation of pressure leaching high iron sphalerite concentrate.

  9. Effects of cropping system and rates of nitrogen in animal slurry and mineral fertilizer on nitrate leaching from a sandy loam

    DEFF Research Database (Denmark)

    Thomsen, Ingrid Kaag; Hansen, Jørgen Frederik; Kjellerup, Viggo K.;

    1993-01-01

    Leaching of nitrate from a sandy loam cropped with spring barley, winter wheat and grass was compared in a 4-year lysimeter study. Crops were grown continuously or in a sequence including sugarbeet. Lysimeters were unfertilized or supplied with equivalent amounts of inorganic nitrogen in calcium...

  10. Preconceptual Design Description for Caustic Recycle Facility

    Energy Technology Data Exchange (ETDEWEB)

    Sevigny, Gary J.; Poloski, Adam P.; Fountain, Matthew S.; Kurath, Dean E.

    2008-04-12

    The U.S. Department of Energy plans to vitrify both high-level and low-activity waste at the Hanford Site in southeastern Washington State. One aspect of the planning includes a need for a caustic recycle process to separate sodium hydroxide for recycle. Sodium is already a major limitation to the waste-oxide loading in the low-activity waste glass to be vitrified at the Waste Treatment Plant, and additional sodium hydroxide will be added to remove aluminum and to control precipitation in the process equipment. Aluminum is being removed from the high level sludge to reduce the number of high level waste canisters produced. A sodium recycle process would reduce the volume of low-activity waste glass produced and minimize the need to purchase new sodium hydroxide, so there is a renewed interest in investigating sodium recycle. This document describes an electrochemical facility for recycling sodium for the WTP.

  11. Sever Gastrointestinal Caustic Injury and Surgical Treatment

    Directory of Open Access Journals (Sweden)

    A Bazrafshan

    2014-04-01

    Full Text Available Approximately 20% of caustic ingestions result in some degree of esophageal injury. Alkaline materials are the most frequent corrosive materials ingested.     The physical form and PH of ingested materials play a critical role in the site and type of gastrointestinal injury (PH > 12 or PH < 1.5, crystalline drain cleaners. Unlike Alkaline solutions, strong acids are bitter, burn on contact and usually produce vomiting but when swallowed pass rapidly through the esophagus and damage the antrum of the stomach. I will present the results of 5 cases of gastric out let obstruction after acid ingestion (subtotal gastrectomy and billroth 1 and 4 patients with extensive esophageal damage and perforation ( Total esophagectomy and gastric pull up.  

  12. Process Development for Permanganate Addition During Oxidative Leaching of Hanford Tanks Sludges

    Energy Technology Data Exchange (ETDEWEB)

    Rapko, Brian M.; Lumetta, Gregg J.; Deschane, Jaquetta R.; Peterson, Reid A.; Blanchard, David L.

    2007-10-30

    Previous Bechtel National, Incorporated (BNI)-sponsored studies have targeted optimizing sodium permanganate for the selective oxidation of chromium from washed Hanford tank sludges (Rapko et al. 2004; Rapko et al. 2005). The recommendation from previous work was that contact with sodium permanganate in a minimally caustic solution, i.e., 0.1 to 0.25 M [OH-] initially, provided maximum Cr dissolution while minimizing concomitant Pu dissolution. At the request of BNI, further work on oxidative alkaline leaching was performed.

  13. P-Area Acid/Caustic Basin groundwater monitoring report: Third quarter 1994

    International Nuclear Information System (INIS)

    During third quarter 1994, groundwater from the six PAC monitoring wells at the P-Area Acid/Caustic Basin was analyzed for herbicides/pesticides, indicator parameters, metals, nitrate, radionuclide indicators, and other constituents. Monitoring results that exceeded the final Primary Drinking Water Standards (PDWS) or the Savannah River Site (SRS) flagging criteria or turbidity standard during the quarter are discussed in this report. During third quarter 1994, no constituents exceeded the final PDWS. Aluminum exceeded its SRS Flag 2 criterion in all six PAC wells. Iron and manganese exceeded Flag 2 criteria in three wells, while turbidity was elevated in one well. Groundwater flow direction and rate in the water table beneath the P-Area Acid/Caustic Basin were similar to past quarters

  14. K-Area Acid/Caustic Basin groundwater monitoring report. Third quarter 1994

    International Nuclear Information System (INIS)

    During third quarter 1994, samples from the KAC monitoring wells at the K-Area Acid/Caustic Basin were collected and analyzed for herbicides/pesticides, indicator parameters, metals, nitrate, radionuclide indicators, and other constituents. Monitoring results that exceeded the final Primary Drinking Water Standards (PDWS), other Savannah River Site (SRS) Flag 2 criteria, or the SRS turbidity standard are provided in this report. No constituents exceeded the final PDWS in the KAC wells. Aluminum and iron exceeded other SRS flagging criteria in one or more of the downgradient wells. Groundwater flow direction and rate in the water table beneath the K-Area Acid/Caustic Basin were similar to past quarters

  15. Dynamic leaching test of personal computer components.

    Science.gov (United States)

    Li, Yadong; Richardson, Jay B; Niu, Xiaojun; Jackson, Ollie J; Laster, Jeremy D; Walker, Aaron K

    2009-11-15

    A dynamic leaching test (DLT) was developed and used to evaluate the leaching of toxic substances for electronic waste in the environment. The major components in personal computers (PCs) including motherboards, hard disc drives, floppy disc drives, and compact disc drives were tested. The tests lasted for 2 years for motherboards and 1.5 year for the disc drives. The extraction fluids for the standard toxicity characteristic leaching procedure (TCLP) and synthetic precipitation leaching procedure (SPLP) were used as the DLT leaching solutions. A total of 18 elements including Ag, Al, As, Au, Ba, Be, Cd, Cr, Cu, Fe, Ga, Ni, Pd, Pb, Sb, Se, Sn, and Zn were analyzed in the DLT leachates. Only Al, Cu, Fe, Ni, Pb, and Zn were commonly found in the DLT leachates of the PC components. Their leaching levels were much higher in TCLP extraction fluid than in SPLP extraction fluid. The toxic heavy metal Pb was found to continuously leach out of the components over the entire test periods. The cumulative amounts of Pb leached out of the motherboards in TCLP extraction fluid reached 2.0 g per motherboard over the 2-year test period, and that in SPLP extraction fluid were 75-90% less. The leaching rates or levels of Pb were largely affected by the content of galvanized steel in the PC components. The higher was the steel content, the lower the Pb leaching rate would be. The findings suggest that the obsolete PCs disposed of in landfills or discarded in the environment continuously release Pb for years when subjected to landfill leachate or rains. PMID:19616380

  16. Leaching of lead from zinc leach residue in acidic calcium chloride aqueous solution

    Science.gov (United States)

    Wang, Le; Mu, Wen-ning; Shen, Hong-tao; Liu, Shao-ming; Zhai, Yu-chun

    2015-05-01

    A process with potentially reduced environmental impacts and occupational hazards of lead-bearing zinc plant residue was studied to achieve a higher recovery of lead via a cost-effective and environmentally friendly process. This paper describes an optimization study on the leaching of lead from zinc leach residue using acidic calcium chloride aqueous solution. Six main process conditions, i.e., the solution pH value, stirring rate, concentration of CaCl2 aqueous solution, liquid-to-solid (L/S) ratio, leaching temperature, and leaching time, were investigated. The microstructure and components of the residue and tailing were characterized using scanning electron microscopy (SEM) and X-ray diffraction (XRD). On the basis of experimental results, the optimum reaction conditions were determined to be a solution pH value of 1, a stirring rate of 500 r·min-1, a CaCl2 aqueous solution concentration of 400 g·L-1, a liquid-to-solid mass ratio of 7:1, a leaching temperature of 80°C, and a leaching time of 45 min. The leaching rate of lead under these conditions reached 93.79%, with an iron dissolution rate of 19.28%. Silica did not take part in the chemical reaction during the leaching process and was accumulated in the residue.

  17. EFRT M-12 Issue Resolution: Comparison of PEP and Bench-Scale Oxidative Leaching Results

    Energy Technology Data Exchange (ETDEWEB)

    Rapko, Brian M.; Schonewill, Philip P.; Brown, Christopher F.; Eslinger, Paul W.; Fountain, Matthew S.; Hausmann, Tom S.; Huckaby, James L.; Hanson, Brady D.; Kurath, Dean E.; Minette, Michael J.

    2010-01-01

    Pacific Northwest National Laboratory (PNNL) has been tasked by Bechtel National Inc. (BNI) on the River Protection Project-Hanford Tank Waste Treatment and Immobilization Plant (RPP-WTP) project to perform research and development activities to resolve technical issues identified for the Pretreatment Facility (PTF). The Pretreatment Engineering Platform (PEP) was designed, constructed, and operated as part of a plan to respond to issue M12, “Undemonstrated Leaching Processes” of the External Flowsheet Review Team (EFRT) issue response plan.( ) The PEP is a 1/4.5-scale test platform designed to simulate the WTP pretreatment caustic leaching, oxidative leaching, ultrafiltration solids concentration, and slurry washing processes. The PEP replicates the WTP leaching processes using prototypic equipment and control strategies. The PEP also includes non-prototypic ancillary equipment to support the core processing.

  18. Test report - 241-AN-274 Caustic Pump Control Building

    Energy Technology Data Exchange (ETDEWEB)

    Paintner, G.P.

    1995-05-01

    This Acceptance Test Report documents the test results of test procedure WHC-SD-WM-ATP-135 `Acceptance Test Procedure for the 241-AN- 274 Caustic Pump Control Building.` The objective of the test was to verify that the 241-AN-274 Caustic Pump Control Building functions properly based on design specifications per applicable H-2-85573 drawings and associated ECN`s. The objective of the test was met.

  19. Predictability of outcome of caustic ingestion by esophagogastroduodenoscopy in children

    Institute of Scientific and Technical Information of China (English)

    Abdulkerim Temiz; Pelin Oguzkurt; Semire Serin Ezer; Emine Ince; Akgun Hicsonmez

    2012-01-01

    AIM:To assess the necessity of esophagogastroduodenoscopy (EGD) to predict the outcome of caustic ingestion in children.METHODS:The study included 206 children who underwent EGD because of ingestion of caustic substances between January 2005 and August 2010.Retrospective analysis of data of the patients was performed.RESULTS:The male/female ratio was 1.6 and mean age was 38.1 ± 28.8 mo.The caustic substances were acidic in 72 (34.9%) cases,alkaline in 56 (27.2%),liquid household bleach in 62 (30.1%),and unknown in 16 (7.8%).Fifty-seven (27.7%) patients were symptom-free.Significant clinical findings were observed in 149 (72.3%) patients.Upper gastrointestinal endoscopy findings of esophageal injury were grade 0 in 86 (41.7%) patients,grade 1 in 49 (23.8%),grade 2a in 42 (20.4%),grade 2b in 28 (13.6%),and grade 3a in 1 (0.5%) patient.35 patients with grade 2a,2b,and 3a injuries underwent esophageal dilation at second week of ingestion.Esophageal stricture,which necessitated a regular dilation program developed in 13 of the aforementioned 35 patients.There is no statistically significant difference in the rate of development of esophageal stricture between the patients who ingested acidic (15.3%) and alkaline (8.9%) substances (P =0.32).Severe gastric injury was detected in 38 (18.5%)patients.The rate of development of gastric injury was significantly higher in the acidic group (14%) than in the alkaline group (2.9%) (P =0.001).Out of 149 patients with clinical findings,49 (32.9%) patients had no esophageal injury and 117 (78.5%) patients had no gastric lesion.Esophageal and severe gastric injuries were detected in 20 (35.1%) and 8 (14%) of patients with no clinical findings respectively.Pyloric stenosis developed in 6 patients.Pyloric obstruction improved with balloon dilation in 2 patients.Mean hospitalization time were 1.2±0.5 d for grade 0 and 2.3 ± 5 d for grade 1 and 6.3 ± 6.2 d for grade 2a and 15.8 ± 18.6d for

  20. Study on Leaching Rate of Metal Cobalt in Wasting Lithium Ion Battery%废旧锂离子电池中有价金属钴的回收研究

    Institute of Scientific and Technical Information of China (English)

    叶芳; 林文川

    2014-01-01

    Xylenol orange spectrophotometric method was used to study the leaching rate of the cobalt in worn -out lithium-ion battery.The heating time , the volume of hydrogen peroxide solution , sulfuric acid concentration , solid -liquid ratio , reaction temperature and so on single optimum determination were explored , and leaching rate of cobalt was investigated in waste lithium ion battery with the best condition of determination above.Experimental showed when the volume of hydrogen peroxide was 2 mL, sulfuric acid concentration was 2 mol/L, water bath temperature was 70℃, solid-liquid ratio was 1:40 , the heating time was 60 min, and leaching rate of Co 2+was 94.9%in lithium ion batteries.%利用用二甲酚橙分光光度法对废旧锂离子电池中钴浸出率进行研究。探索了加热时间、加入双氧水体积、硫酸浓度、固液比、反应温度等单项最佳测定条件,并在最佳条件下测定废旧锂离子电池中钴的浸出率。实验研究证明,当在加入双氧水的体积为2 mL、加入硫酸的浓度为2 mol/L、水浴温度为70℃、固液比为1砄40、加热时间为60 min时,废旧锂离子电池中Co2+的浸出率为94.9%。

  1. In situ leaching of uranium

    International Nuclear Information System (INIS)

    A process is described for the in-situ leaching of uranium-containing ores employing an acidic leach liquor containing peroxymonosulphuric acid. Preferably, additionally, sulphuric acid is present in the leach liquor. (author)

  2. Illuminating Hot Jupiters in caustic crossing

    CERN Document Server

    Sajadian, Sedighe

    2010-01-01

    In recent years a large number of Hot Jupiters orbiting in a very close orbit around the parent stars have been explored with the transit and doppler effect methods. Here in this work we study the gravitational microlensing effect of a binary lens on a parent star with a Hot Jupiter revolving around it. Caustic crossing of the planet makes enhancements on the light curve of the parent star in which the signature of the planet can be detected by high precision photometric observations. We use the inverse ray shooting method with tree code algorithm to generate the combined light curve of the parent star and the planet. In order to investigate the probability of observing the planet signal, we do a Monte-Carlo simulation and obtain the observational optical depth of $\\tau \\sim 10^{-8}$. We show that about ten years observations of Galactic Bulge with a network of telescopes will enable us detecting about ten Hot Jupiter with this method. Finally we show that the observation of the microlensing event in infra-re...

  3. Stranded Zostera marina L. vs wrack fauna community interactions on a Baltic sandy beach (Hel, Poland: a short-term pilot study. Part I. Driftline effects of fragmented detritivory, leaching and decay rates

    Directory of Open Access Journals (Sweden)

    Marcin F. Jêdrzejczak

    2002-06-01

    Full Text Available The effects of the beach community structure of macro- and meiofauna on the process of beach wrack decay were investigated by means of a simple field colonisation experiment in a temperate, fine quartz sediment, sandy beach at the end of the Hel Peninsula in Poland. 1260 replicate litterbags of three mesh sizes (12 mm, 0.5 mm, 48 µm containing fresh wrack were used to assess the role of faunal and non-faunal components in the breakdown of stranded Zostera marina. Wrack breakdown was determined during a three-year field study. This paper presents the first part of the results of this field experiment, which refer to the effects of fragmentation detritivory, leaching and decay rates. Material was lost from the bags at a rapid rate, with only 22-32% of the original dry mass remaining after 27 days in the field. This degradation was not directly related to the faunal succession of the eelgrass tissue, which proceeded in two distinct phases throughout the study period. Exclusion of macrofauna from the wrack by the use of finer-mesh litterbags (< 1 mm had no appreciable effect on the rate of dry matter loss. Microbial decay, and abiotic leaching and fragmentation are probably the major causes of seagrass weight loss from the litterbags.

  4. Continuous-flow leaching studies of crushed and cored SYNROC

    International Nuclear Information System (INIS)

    Both crushed (150 to 300 μm) and cored (1.8 mm diameter) samples of SYNROC have been leached with the single-pass continuous-flow leaching equipment. Crushed samples of Cs-hollandite were also leached in a similar experiment. Temperatures used were 25 and 750C and leachates were 0.03 N NaHCO3 and distilled water. Leaching rates from SYNROC C were ranked Cs > Sr greater than or equal to Ca > Ba > Zr. A comparison of leaching rates is made between crushed SYNROC, cored SYNROC, and PNL 76-68 glass beads. This comparison depends on how the surface areas are determined for each sample. Based on geometric surface areas for SYNROC cores and glass beads Cs leach rates from SYNROC compare well with both Na and Np leached from the glass. The other elements leached from SYNROC are lower than Na and Np leached from glass. They also vary for each element while glass shows nearly the same leach rate for both Na and Np

  5. Kinetics of Leaching Flavonoids from Pueraria Lobata with Ethanol%乙醇从葛根中提取黄酮动力学

    Institute of Scientific and Technical Information of China (English)

    池汝安; 田君; 高洪; 周芳; 刘敏; 王存文; 吴元欣

    2006-01-01

    The kinetics of leaching flavonoids from Pueraria Lobata with ethanol was investigated. The effects of leaching temperature, mechanical agitation rate, concentration of ethanol and feed particle size on leaching kinetics were examined. It is found that the smaller the feed particle size or the higher the leaching temperature, the higher the leaching rate. The leaching process can be described by the shrinking-core model. The apparent activation energy is 10.8kJ·mol-1, suggesting that the leaching process is controlled by the inner diffusion. An empirical equation relating the flavonoids leaching rate constant to the feed particle size and leaching temperature was expected.

  6. Kinetic process of oxidative leaching of chalcopyrite under low oxygen pressure and low temperature

    Institute of Scientific and Technical Information of China (English)

    QIU Ting-sheng; NIE Guang-hua; WANG Jun-feng; CUI Li-feng

    2007-01-01

    Kinetic process of oxidative leaching of chalcopyrite in chloride acid hydroxide medium under oxygen pressure and low temperature was investigated. The effect on leaching rate of chalcopyrite caused by these factors such as ore granularity, vitriol concentration, sodium chloride concentration, oxygen pressure and temperature was discussed. The results show that the leaching rate of chalcopyrite increases with decreasing the ore granularity. At the early stage of oxidative reaction, the copper leaching rate increases with increasing the oxygen pressure and dosage of vitriol concentration, while oxygen pressure affects leaching less at the later stage. At low temperature, the earlier oxidative leaching process of chalcopyrite is controlled by chemical reactions while the later one by diffusion. The chalcopyrite oxidative leaching rate has close relation with ion concentration in the leaching solution. The higher ion concentration is propitious for chalcopyrite leaching.

  7. CODCr leaching rules of municipal solid waste in Songtao Reservoir,Hainan Province,China

    Institute of Scientific and Technical Information of China (English)

    陈大勇; 王里奥

    2009-01-01

    By the means of static leaching experiment and dynamic leaching experiment,CODCr leaching rules of dumped MSW(Municipal Solid Waste) in Songtao Reservoir,Hainan Province,China,were studied. And according to academic experience and fitted results of experiment data,the models of CODCr leaching rules in the leaching condition were deduced. The static leaching experiment indicates that,both in water-changing section and no-water-changing section,the ratio of liquid to solid has a remarkable influence on CODCr leaching concentration. The exponential model could be established to approximately describe CODCr leaching rules and the curve fits well. The dynamic leaching experiment indicates that,leaching rules of MSW can be approximately described by power model,which can well fit the leaching experiment data. By the contrast of the static leaching experiment and dynamic leaching experiment,the differences of CODCr leaching rules between the two experiments are significant. By the exponential model,the average static leaching rate of CODCr is calculated as 882.24 mg/(kg·d) for water-changing section and 320.39 mg/(kg·d) for no-water-changing section; by the power model,the average dynamic leaching rate of CODCr is 208.77 mg/(kg·d).

  8. Caustic Structures and Detectability of Circumbinary Planets in Microlensing

    Science.gov (United States)

    Luhn, Jacob K.; Penny, Matthew T.; Gaudi, B. Scott

    2016-08-01

    Recent discoveries of circumbinary planets in Kepler data show that there is a viable channel of planet formation around binary main-sequence stars. Motivated by these discoveries, we have investigated the caustic structures and detectability of circumbinary planets in microlensing events. We have produced a suite of animations of caustics as a function of the projected separation and angle of the binary host to efficiently explore caustic structures over the entire circumbinary parameter space. Aided by these animations, we have derived a semi-empirical analytic expression for the location of planetary caustics, which are displaced in circumbinary lenses relative to those of planets with a single host. We have used this expression to show that the dominant source of caustic motion will be due to the planet’s orbital motion and not that of the binary star. Finally, we estimate the fraction of circumbinary microlensing events that are recognizable as such to be significant (5%–50%) for binary projected separations in the range 0.1–0.5 in units of Einstein radii.

  9. Leaching and recycling of zinc from liquid waste sediments

    Institute of Scientific and Technical Information of China (English)

    PENG Bing; GAO Hui-mei; CHAI Li-yuan; SHU Yu-de

    2008-01-01

    The selective leaching and recovery of zinc in a zinciferous sediment from a synthetic wastewater treatment was investigated. The main composition of the sediment includes 6% zinc and other metal elements such as Ca, Fe, Cu, Mg. The effects of sulfuric acid concentration, temperature, leaching time and the liquid-to-solid ratio on the leaching rate of zinc were studied by single factor and orthogonal experiments. The maximum difference of leaching rate between zinc and iron, 89.85%, was obtained by leaching under 170 g/L H2SO4 in liquid-to-solid ratio 4.2 mL/g at 65 "C for 1 h, and the leaching rates of zinc and iron were 91.20% and 1.35%, respectively.

  10. Caustics and Rogue Waves in an Optical Sea

    CERN Document Server

    Mathis, Amaury; Toenger, Shanti; Dias, Frederic; Genty, Goery; Dudley, John M

    2015-01-01

    There are many examples in physics of systems showing rogue wave behaviour, the generation of high amplitude events at low probability. Although initially studied in oceanography, rogue waves have now been seen in many other domains, with particular recent interest in optics. Although most studies in optics have focussed on how nonlinearity can drive rogue wave emergence, purely linear effects have also been shown to induce extreme wave amplitudes. In this paper, we report a detailed experimental study of linear rogue waves in an optical system, using a spatial light modulator to impose random phase structure on a coherent optical field. After free space propagation, different random intensity patterns are generated, including partially-developed speckle, a broadband caustic network, and an intermediate pattern with characteristics of both speckle and caustic structures. Intensity peaks satisfying statistical criteria for rogue waves are seen especially in the case of the caustic network, and are associated w...

  11. Caustics of exotic ($1/r^n$) binary gravitational lenses

    CERN Document Server

    Bozza, V

    2015-01-01

    With some violation of the energy conditions, it is possible to combine scalar fields or other types of matter so as to build metrics that fall as $1/r^n$ asymptotically, one famous example being the Ellis wormhole. Gravitational lensing provides a natural arena to distinguish and identify such exotic objects in our Universe. In fact, these metrics predict the possibility to defocus light, which is impossible with ordinary matter. In this paper we continue the investigation of gravitational lensing in this new realm by providing a thorough study of critical curves and caustics produced by binary exotic lenses. We find that there are still three topologies as in the standard binary lens, with the main novelty coming from the secondary caustics of the close topology, which become huge at higher $n$. After drawing caustics by numerical methods, we derive a large amount of analytical formulae in all limits that are useful to provide deeper insight in the mathematics of the problem.

  12. Uranium leaching by fungal metabolite

    International Nuclear Information System (INIS)

    To explore new means of bioleaching, one strain of high-yielding fungi-Aspergillus niger which could produce organic acids was separated and purified from soil samples of uranium mine. The influence of cultural temperature, initial pH value, inoculum sizes on its growth characteristics were carried out. And the tests of uranium leaching of metabolin of Aspergillus niger were operated. On these tests, the effects of metabolin of Aspergillus niger with different pH value produced in the diverse culture temperature on uranium leaching were investigated. The results show that this strain of Aspergillus niger can grow best under the following conditions: the temperature is 37℃, the initial pH value is 7.0, the inoculum sizes is 2% (the OD value of the spores solution is 0.06). The uranium extraction effects relative to the final pH value of the cultures. and the maximum leaching rates is 83.05% when the pH value is 2.3. (authors)

  13. A systematic fitting scheme for caustic-crossing microlensing events

    DEFF Research Database (Denmark)

    Kains ...[et al], N.; Jørgensen, Uffe Gråe

    2009-01-01

    We outline a method for fitting binary-lens caustic-crossing microlensing events based on the alternative model parametrization proposed and detailed by Cassan. As an illustration of our methodology, we present an analysis of OGLE-2007-BLG-472, a double-peaked Galactic microlensing event with a...... source crossing the whole caustic structure in less than three days. In order to identify all possible models we conduct an extensive search of the parameter space, followed by a refinement of the parameters with a Markov Chain Monte Carlo algorithm. We find a number of low-chi(2) regions in the...

  14. Wavefield extrapolation in caustic-free normal ray coordinates

    KAUST Repository

    Ma, Xuxin

    2012-11-04

    Normal ray coordinates are conventionally constructed from ray tracing, which inherently requires smooth velocity profiles. To use rays as coordinates, the velocities have to be smoothed further to avoid caustics, which is detrimental to the mapping process. Solving the eikonal equation numerically for a line source at the surface provides a platform to map normal rays in complex unsmoothed velocity models and avoid caustics. We implement reverse-time migration (RTM) and downward continuation in the new ray coordinate system, which allows us to obtain efficient images and avoid some of the dip limitations of downward continuation.

  15. 21 CFR 2.110 - Definition of ammonia under Federal Caustic Poison Act.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 1 2010-04-01 2010-04-01 false Definition of ammonia under Federal Caustic Poison... SERVICES GENERAL GENERAL ADMINISTRATIVE RULINGS AND DECISIONS Caustic Poisons § 2.110 Definition of ammonia under Federal Caustic Poison Act. For the purpose of determining whether an article containing...

  16. Electrochemical generation of Fenton's reagent to treat spent caustic wastewater

    Energy Technology Data Exchange (ETDEWEB)

    Hansen, H. K.; Nunez, P.; Rodriguez, N.; Guzman, J.

    2009-07-01

    An important wastewater stream from oil refineries is the spent caustic. Caustic solutions are used as scrubbing agent during the desulphurization process to eliminate sulphur an mercaptans from oil and gasses. Spent caustic is classified as DOO3 (reactive sulphide) hazardous waste under the US Resource Conservation and Recovery Act (RCRA). (Author)

  17. 18种袋泡茶型保健食品铅浸出率和人群摄入量研究%Study on leaching rate and intake on lead in 18 kinds of teabag-healthy foods

    Institute of Scientific and Technical Information of China (English)

    孙鑫贵; 沙博郁; 王正; 沙怡梅; 罗仁才

    2013-01-01

    目的 了解袋泡茶型保健食品铅的浸出率和人群摄入量,为进一步评估其安全性提供基础数据.方法 从北京市商场、超市、药店购买18种袋泡茶型保健食品,按照GB5009.12-2010检测样品和浸提液中铅含量.用产品中铅含量与产品标识的食用量和铅的浸出率相乘计算铅的摄入量.采用联合国粮农组织和世界卫生组织食品添加剂联合专家委员会推荐的暂定每周耐受摄入量(PTWI)值评价铅摄入的安全性.结果 袋泡茶型保健食品浸泡后铅的浸出量为0.0036~0.5400 mg/kg,平均浸出率为5.49%.人群铅的摄入量为0.018~4.324μg,占暂定每周耐受摄入量(PTWI)的最高比例为2.0%,平均仅为0.8%.结论 18种袋泡茶型保健食品铅的摄入量是安全的,但个别产品较高的铅含量应引起监管部门关注.%OBJECTIVE To investigate leaching rate of lead from teabag-healthy foods and the intake amount of lead of per person from it and to provide scientific data used to further evaluate the safety of lead level in it. METHODS 18 products were purchased from markets in Beijing. The contents of lead both in samples and leaching liquid were determined according to the standard method of GB5008.12-2010. The intake level of lead was obtained by timing the lead content, leaching rate of lead in teabag-healthy foods and labeling dosage. The intake safety of lead was assessed by Provisional Tolerable Weekly Intake (PTWI) recommended by JECFA of WHO/FAO. RESULTS The content of lead leached from products was from 0.003 6 mg/kg to 0.540 0 mgAg, with the average leaching rate was 5.49%. The intake level of lead from teabag-healthy foods was 0.018-4.324μg. The average ratio of intake level of lead in PTWI was only 0.8%, while the maximum was 2.0%. CONCLUSION The intake of lead in 18 kinds of teabag-health foods is safe, but the higher lead content in individual products should be concerned by food hygiene supervision departments.

  18. Characterization of irregular seeds on gibbsites precipitated from caustic aluminate solutions

    Institute of Scientific and Technical Information of China (English)

    CHEN Guo-hui; CHEN Qi-yuan; YIN Zhou-lan; YIN Zhi-min

    2006-01-01

    The irregular surface of seeds on which gibbsites are precipitated from caustic aluminate solutions, was investigated according to the fractal theory. Two kinds of fractal dimensions were used to characterize these irregularity. Box-dimension and spectral dimension are based on the SEM images of seeds and diffusive dynamic equation ofthe precipitation respectively. Both these two dimensions are affected by the reaction temperature, evolved with different reaction conditions and can reflect the influence of irregularity of seeds on the precipitation rate. Box dimension is fit for the characterization of the irregular morphology of seeds, while spectral dimension can explain the fractal dynamic behavior.

  19. Optimization of the factors that accelerate leaching

    International Nuclear Information System (INIS)

    The prediction of long-term leachability of low-level radioactive waste forms is an essential element of disposal-site performance assessment. This report describes experiments and modeling techniques used to develop an accelerated leach test that meets this need. The acceleration in leaching rates caused by the combinations of two or more factors were experimentally determined. These factors were identified earlier as being able to individually accelerate leaching. They are: elevated temperature, the size of the waste form, the ratio of the volume of leachant to the surface area of the waste form, and the frequency of replacement of the leachant. The solidification agents employed were ones that are currently used to treat low-level radioactive wastes, namely portland type I cement, bitumen, and vinyl ester-styrene. The simulated wastes, sodium sulfate, sodium tetraborate, and incinerator ash, are simplified representatives of typical low-level waste streams. Experiments determined the leaching behavior of the radionuclides of cesium (Cs-137), strontium (Sr-85), and cobalt (Co-60 or Co-57) from several different formulations of solidification agents and waste types. Leaching results were based upon radiochemical and elemental analyses of aliquots of the leachate, and on its total alkalinity and pH at various times during the experiment (up to 120 days). Solid phase analyses were carried out by Scanning/Electron Microscopy and Energy Dispersive Spectroscopy on the waste forms before and after some leaching experiments. 43 refs., 96 figs., 16 tabs

  20. Lixiviação de potássio no solo de acordo com suas doses aplicadas sobre palha de milheto Potassium leaching in soil as affected by potassium fertilizer rates applied over pearl millet straw

    Directory of Open Access Journals (Sweden)

    Ciro Antonio Rosolem

    2006-10-01

    Full Text Available A presença de palha na superfície do solo influi na ciclagem do K do sistema de produção e pode alterar as propriedades químicas do solo, com possíveis reflexos na lixiviação do nutriente. No presente trabalho, foi avaliada a lixiviação de K no perfil de um solo submetido a 30 mm de chuva simulada, de acordo com doses de K aplicadas a lanço, na presença e ausência de palha de milheto na superfície do solo. O milheto foi cultivado por 55 dias em condições controladas. A seguir, foi cortado à altura do colo, em pedaços de 3 a 5 cm e colocado sobre o solo, em vasos de PVC com 20 cm de diâmetro, em quantidade equivalente a 8 t ha-1 do material seco. Sobre a palha foi aplicado cloreto de K, correspondente às doses de 0, 40, 80, 120 e 160 kg ha-1. A seguir, os vasos foram submetidos à chuva simulada equivalente a 30 mm. A palha foi coletada e analisada quanto aos teores de K, assim como o solo foi amostrado nas profundidades de 0-2, 2-4, 4-8, 8-12 e 12-20 cm de profundidade para análise de K trocável. A chuva de 30 mm foi necessária e suficiente para carrear para o solo o fertilizante potássico aplicado sobre a palha. A intensidade de lixiviação do K no perfil do solo foi proporcional à dose aplicada, de modo que uma chuva de 30 mm lixiviou o nutriente até a camada de 8-12 cm de profundidade, quando o solo estava descoberto. A presença de palha de milheto na superfície do solo aumentou a quantidade de K levada até à superfície do solo pela chuva, mas diminuiu a intensidade de lixiviação do nutriente.The presence of straw on soil surface affects K cycling in the production system and can affect soil chemistry by modifying K leaching rate and intensity. An experiment was conducted to evaluate K leaching as affected by 30 mm of simulated rain over pearl millet straw receiving several broadcasted K rates. Pearl millet was grown for 55 days in a green house and then cut at soil level into pieces of 3 to 5 cm. Then it was

  1. Uranium in situ leaching

    International Nuclear Information System (INIS)

    Despite the depressed situation that has affected the uranium industry during the past years, the second Technical Committee Meeting on Uranium In Situ Leaching, organized by the International Atomic Energy Agency and held in Vienna from 5 to 8 October 1992, has attracted a relatively large number of participants. A notable development since the first meeting was that the majority of the contributions came from the actual operators of in situ leaching uranium production. At the present meeting, presentations on operations in the USA were balanced by those of the eastern European and Asian countries. Contributions from Bulgaria, China, Czechoslovakia, Germany (from the operation in the former German Democratic Republic), the Russian Federation and Uzbekistan represent new information not commonly available. In situ leach mining is defined in one of the paper presented as a ''mining method where the ore mineral is preferentially leached from the host rock in place, or in situ, by the use of leach solutions, and the mineral value is recovered. Refs, figs and tabs

  2. Leaching of DOC, DN, and inorganic constituents from scrap tires.

    Science.gov (United States)

    Selbes, Meric; Yilmaz, Ozge; Khan, Abdul A; Karanfil, Tanju

    2015-11-01

    One concern for recycle and reuse of scrap tires is the leaching of tire constituents (organic and inorganic) with time, and their subsequent potential harmful impacts in environment. The main objective of this study was to examine the leaching of dissolved organic carbon (DOC), dissolved nitrogen (DN), and selected inorganic constituents from scrap tires. Different sizes of tire chips and crumb rubber were exposed to leaching solutions with pH's ranging from 3.0 to 10.0 for 28days. The leaching of DOC and DN were found to be higher for smaller size tire chips; however, the leaching of inorganic constituents was independent of the size. In general, basic pH conditions increased the leaching of DOC and DN, whereas acidic pH conditions led to elevated concentrations of metals. Leaching was minimal around the neutral pH values for all the monitored parameters. Analysis of the leaching rates showed that components associated with the rubbery portion of the tires (DOC, DN, zinc, calcium, magnesium, etc.) exhibited an initial rapid followed by a slow release. On the other hand, a constant rate of leaching was observed for iron and manganese, which are attributed to the metal wires present inside the tires. Although the total amounts that leached varied, the observed leaching rates were similar for all tire chip sizes and leaching solutions. Operation under neutral pH conditions, use of larger size tire chips, prewashing of tires, and removal of metal wires prior to application will reduce the impact of tire recycle and reuse.

  3. Leaching of DOC, DN, and inorganic constituents from scrap tires.

    Science.gov (United States)

    Selbes, Meric; Yilmaz, Ozge; Khan, Abdul A; Karanfil, Tanju

    2015-11-01

    One concern for recycle and reuse of scrap tires is the leaching of tire constituents (organic and inorganic) with time, and their subsequent potential harmful impacts in environment. The main objective of this study was to examine the leaching of dissolved organic carbon (DOC), dissolved nitrogen (DN), and selected inorganic constituents from scrap tires. Different sizes of tire chips and crumb rubber were exposed to leaching solutions with pH's ranging from 3.0 to 10.0 for 28days. The leaching of DOC and DN were found to be higher for smaller size tire chips; however, the leaching of inorganic constituents was independent of the size. In general, basic pH conditions increased the leaching of DOC and DN, whereas acidic pH conditions led to elevated concentrations of metals. Leaching was minimal around the neutral pH values for all the monitored parameters. Analysis of the leaching rates showed that components associated with the rubbery portion of the tires (DOC, DN, zinc, calcium, magnesium, etc.) exhibited an initial rapid followed by a slow release. On the other hand, a constant rate of leaching was observed for iron and manganese, which are attributed to the metal wires present inside the tires. Although the total amounts that leached varied, the observed leaching rates were similar for all tire chip sizes and leaching solutions. Operation under neutral pH conditions, use of larger size tire chips, prewashing of tires, and removal of metal wires prior to application will reduce the impact of tire recycle and reuse. PMID:25712610

  4. Laser Beam Caustic Measurement with Focal Spot Analyser

    DEFF Research Database (Denmark)

    Olsen, Flemming Ove; Gong, Hui; Bagger, Claus

    2005-01-01

    In industrial applications of high power CO2-lasers the caustic characteristics of the laser beam have great effects on the performance of the lasers. A welldefined high intense focused spot is essential for reliable production results. This paper presents a focal spot analyser that is developed...... for measuring the beam profiles of focused high power CO2-lasers....

  5. Test Procedure - pumping system for caustic addition project

    International Nuclear Information System (INIS)

    This test procedure provides the requirements for sub-system testing and integrated operational testing of the submersible mixer pump and caustic addition equipment by WHC and Kaiser personnel at the Rotating Equipment Shop run-in pit (Bldg. 272E)

  6. Measurement of leached hulls

    International Nuclear Information System (INIS)

    Leached hulls are the short lengths of fuel rod cladding and fuel element hardware which constitute a major waste product of a reprocessing plant employing a chop-and-leach head-end process. The small, undissolved fuel residue (0.1 to 1.0% of original fuel content) which is discarded with this waste must be measured for safeguards, material accountability, and process control reasons. This report gives a critical analysis of hull measurement techniques involving the analysis of fission product gamma rays, spontaneous fission neutrons from curium, and delayed neutron activation. Major emphasis is given to the measurement of 2186-keV gamma rays from 144Ce--144Pr. A detailed description of typical leached hull characteristics is presented at the beginning of the report. An extensive review of experience gained from existing hull measurement systems in the United Kingdom, France, Japan, Germany, Italy, and the United States is presented

  7. Kinetic model for simultaneous leaching of zinc sulfide and manganese dioxide in the presence of iron-oxidizing bacteria

    OpenAIRE

    KAI, Takami; Suenaga, Yo-ich; Migita, Atsuko; TAKAHASHI, Takeshige

    2000-01-01

    The effect of iron-oxidizing bacteria on the simultaneous leaching of zinc sulfide and manganese dioxide was studied. Some researchers have reported the enhancement of the leaching rate during the simultaneous leaching of metal oxides and metal sulfides. In the present study, we examined the effect of the presence of Thiobacillus ferrooxidans in the simultaneous leaching. We also examined the reaction rates during the simultaneous leaching in the presence of the bacteria in order to study the...

  8. MECHANISTIC UNDERSTANDING OF CAUSTIC CRACKING OF CARBON STEELS

    Energy Technology Data Exchange (ETDEWEB)

    Garcia-Diaz, B.; Roy, A.

    2009-10-19

    hysteresis during the scan. Analysis of the CPP data was performed to compare the corrosion susceptibility of the samples under different environmental conditions. Test results indicated that the most important factors affecting corrosion of the steel are the solution temperature, hydroxide concentration, and the material used in constructing the tanks. Variables that did not significantly affect the corrosion susceptibility of the steel were the nitrate or nitrite concentration and the atmosphere in the tank. The passivation current of the coupons increased exponentially with temperature. Longer-term studies of the passivation current are suggested based on results from the literature for iron in highly caustic environments. Polarization resistance studies showed a significant increase in corrosion rate at 125 C and 12 M hydroxide concentration when compared with tests at lower temperatures and lower hydroxide concentrations. Within the temperature and pH range of these tests, iron oxide, Fe{sub 3}O{sub 4}, becomes unstable and could account for the increased corrosion susceptibility. The applicability of these conditions should be confirmed and detailed surface studies should be conducted to determine the corrosion resistance of A285 and A516 carbon steels under these conditions. Surface science studies should also be conducted to determine the role of the carbon steel composition in preventing corrosion under these conditions.

  9. Selective Leaching of Chromium from Hanford Tank Sludge 241-U-108

    Energy Technology Data Exchange (ETDEWEB)

    Rapko, Brian M.; Vienna, John D.

    2002-09-09

    This study evaluated the oxidants permanganate, MnO4-, and peroxynitrite, ONOO-, as selective chromium-leaching agents from washed 241-U-108 tank sludge under varying conditions of hydroxide concentration, temperature, and time. The mass changes and final sludge compositions were evaluated using glass-property models to ascertain the relative impacts of the various oxidative alkaline leach conditions on the amount of borosilicate glass required to immobilize a given amount of washed 241-U-108 Hanford tank sludge. Only permanganate leaching removes sufficient chromium to make the chromium concentration in the oxidatively alkaline leached solids non-limiting. In the absence of added oxidants, continued washing or caustic leaching have no beneficial effects. Peroxynitrite addition reduces the amount of glass required to immobilize a given amount of washed 241-U-108 tank sludge by approximately a factor of two. Depending on the leach conditions and the exact chromium concentration limits, contact with alkaline permanganate solutions reduces the amount of immobilized high-level waste glass by a factor of 10 to 30.

  10. Life cycle assessment and residue leaching: The importance of parameter, scenario and leaching data selection

    International Nuclear Information System (INIS)

    Highlights: • Relevance of metal leaching in waste management system LCAs was assessed. • Toxic impacts from leaching could not be disregarded. • Uncertainty of toxicity, due to background activities, determines LCA outcomes. • Parameters such as pH and L/S affect LCA results. • Data modelling consistency and coverage within an LCA are crucial. - Abstract: Residues from industrial processes and waste management systems (WMSs) have been increasingly reutilised, leading to landfilling rate reductions and the optimisation of mineral resource utilisation in society. Life cycle assessment (LCA) is a holistic methodology allowing for the analysis of systems and products and can be applied to waste management systems to identify environmental benefits and critical aspects thereof. From an LCA perspective, residue utilisation provides benefits such as avoiding the production and depletion of primary materials, but it can lead to environmental burdens, due to the potential leaching of toxic substances. In waste LCA studies where residue utilisation is included, leaching has generally been neglected. In this study, municipal solid waste incineration bottom ash (MSWI BA) was used as a case study into three LCA scenarios having different system boundaries. The importance of data quality and parameter selection in the overall LCA results was evaluated, and an innovative method to assess metal transport into the environment was applied, in order to determine emissions to the soil and water compartments for use in an LCA. It was found that toxic impacts as a result of leaching were dominant in systems including only MSWI BA utilisation, while leaching appeared negligible in larger scenarios including the entire waste system. However, leaching could not be disregarded a priori, due to large uncertainties characterising other activities in the scenario (e.g. electricity production). Based on the analysis of relevant parameters relative to leaching, and on general results

  11. Life cycle assessment and residue leaching: The importance of parameter, scenario and leaching data selection

    Energy Technology Data Exchange (ETDEWEB)

    Allegrini, E., E-mail: elia@env.dtu.dk [Technical University of Denmark, Department of Environmental Engineering, Building 115, 2800 Lyngby (Denmark); Butera, S. [Technical University of Denmark, Department of Environmental Engineering, Building 115, 2800 Lyngby (Denmark); Kosson, D.S. [Vanderbilt University, Department of Civil and Environmental Engineering, Box 1831 Station B, Nashville, TN 37235 (United States); Van Zomeren, A. [Energy Research Centre of the Netherlands (ECN), Department of Environmental Risk Assessment, P.O. Box 1, 1755 ZG Petten (Netherlands); Van der Sloot, H.A. [Hans van der Sloot Consultancy, Dorpsstraat 216, 1721 BV Langedijk (Netherlands); Astrup, T.F. [Technical University of Denmark, Department of Environmental Engineering, Building 115, 2800 Lyngby (Denmark)

    2015-04-15

    Highlights: • Relevance of metal leaching in waste management system LCAs was assessed. • Toxic impacts from leaching could not be disregarded. • Uncertainty of toxicity, due to background activities, determines LCA outcomes. • Parameters such as pH and L/S affect LCA results. • Data modelling consistency and coverage within an LCA are crucial. - Abstract: Residues from industrial processes and waste management systems (WMSs) have been increasingly reutilised, leading to landfilling rate reductions and the optimisation of mineral resource utilisation in society. Life cycle assessment (LCA) is a holistic methodology allowing for the analysis of systems and products and can be applied to waste management systems to identify environmental benefits and critical aspects thereof. From an LCA perspective, residue utilisation provides benefits such as avoiding the production and depletion of primary materials, but it can lead to environmental burdens, due to the potential leaching of toxic substances. In waste LCA studies where residue utilisation is included, leaching has generally been neglected. In this study, municipal solid waste incineration bottom ash (MSWI BA) was used as a case study into three LCA scenarios having different system boundaries. The importance of data quality and parameter selection in the overall LCA results was evaluated, and an innovative method to assess metal transport into the environment was applied, in order to determine emissions to the soil and water compartments for use in an LCA. It was found that toxic impacts as a result of leaching were dominant in systems including only MSWI BA utilisation, while leaching appeared negligible in larger scenarios including the entire waste system. However, leaching could not be disregarded a priori, due to large uncertainties characterising other activities in the scenario (e.g. electricity production). Based on the analysis of relevant parameters relative to leaching, and on general results

  12. Characterization and Leach Testing for PUREX Cladding Waste Sludge (Group 3) and REDOX Cladding Waste Sludge (Group 4) Actual Waste Sample Composites

    Energy Technology Data Exchange (ETDEWEB)

    Snow, Lanee A.; Buck, Edgar C.; Casella, Amanda J.; Crum, Jarrod V.; Daniel, Richard C.; Draper, Kathryn E.; Edwards, Matthew K.; Fiskum, Sandra K.; Jagoda, Lynette K.; Jenson, Evan D.; Kozelisky, Anne E.; MacFarlan, Paul J.; Peterson, Reid A.; Swoboda, Robert G.

    2009-02-13

    A testing program evaluating actual tank waste was developed in response to Task 4 from the M-12 External Flowsheet Review Team (EFRT) issue response plan.(a) The testing program was subdivided into logical increments. The bulk water-insoluble solid wastes that are anticipated to be delivered to the Waste Treatment and Immobilization Plant (WTP) were identified according to type such that the actual waste testing could be targeted to the relevant categories. Eight broad waste groupings were defined. Samples available from the 222S archive were identified and obtained for testing. The actual wastetesting program included homogenizing the samples by group, characterizing the solids and aqueous phases, and performing parametric leaching tests. Two of the eight defined groups—plutonium-uranium extraction (PUREX) cladding waste sludge (Group 3, or CWP) and reduction-oxidation (REDOX) cladding waste sludge (Group 4, or CWR)—are the subjects of this report. Both the Group 3 and 4 waste composites were anticipated to be high in gibbsite, requiring caustic leaching. Characterization of the composite Group 3 and Group 4 waste samples confirmed them to be high in gibbsite. The focus of the Group 3 and 4 testing was on determining the behavior of gibbsite during caustic leaching. The waste-type definition, archived sample conditions, homogenization activities, characterization (physical, chemical, radioisotope, and crystal habit), and caustic leaching behavior as functions of time, temperature, and hydroxide concentration are discussed in this report. Testing was conducted according to TP-RPP-WTP-467.

  13. Water flow and nitrate leaching in a layered silt loam

    NARCIS (Netherlands)

    Vos, J.A.; Hesterberg, D.L.R.; Raats, P.A.C.

    2000-01-01

    Nitrate (NO3) leaching was studied for a winter leaching period in a layered calcareous silt loam with tile-drains at about 1-m depth and 12-m spacing. Groundwater levels, drain discharge rates, and NO3 concentrations in the drainage water were monitored, and the soil hydraulic characteristics were

  14. Caustic cracking of 9Cr 1Mo steel at 3000C

    International Nuclear Information System (INIS)

    The stress corrosion cracking of correctly heat-treated 9Cr-1Mo in caustic solutions at 3000C has been examined using a bursting tube version of the slow strain rate technique. Some susceptibility was detected at all concentrations examined, the more concentrated solutions which favoured less protective oxide formation, producing the more severe cracking. The cracking in these strong solutions proceeded at velocities up to 0.1 mm h-1 and produced wide oxide filled cracks. This cracking is not strongly dependent on potential, although more anodic potentials promote thicker oxide formation while cathodic potentials favour general dissolution. Normalized and tempered, annealed, and a simulated heat-affected zone microstructure were all equally susceptible to cracking. Some constant pressure tests were performed which suggested cracking could occur at stresses below the yield stress. In more dilute solutions susceptibility was much less, and the crack velocity was about 0.01 mm h-1, i.e. ten times slower than in 8 M NaOH. The relationship between slow strain rate tests, conventional tests and practical experience are discussed. The behaviour of 9Cr 1Mo in caustic below 2 1/2 M places it in the low susceptibility category and failures under realistic conditions are unlikely. (author)

  15. Sodium sulfide leaching of low-grade jamesonite concentrate in production of sodium pyroantimoniate

    Institute of Scientific and Technical Information of China (English)

    YANG Tian-zu; JIANG Ming-xi; LAI Qiong-lin; CHEN Jin-zhong

    2005-01-01

    Sodium sulfide leaching of a low-grade jamesonite concentrate in the production of sodium pyroantimoniate through the air oxidation process and the influencing factors on the leaching rate of antimony were investigated.In order to decrease the consumption of sodium sulfide and increase the concentration of antimony in the leaching solution, two-stage leaching of jamesonite concentrate and combination leaching of high-grade stibnite concentrate and jamesonite concentrate were used. The experimental results showthat the consumptions of sodium sulfide for the two-stage leaching process and the combination leaching process are decreased by 20% and 60% compared to those of one-stage leaching process respectively. The final concentrations of antimony in the leaching solutions of both processes are above 100 g/L.

  16. CHEMICAL STABILITY OF POLYPHENYLENE SULFIDE IN THE NEXT GENERATION SOLVENT FOR CAUSTIC-SIDE SOLVENT EXTRACTION

    Energy Technology Data Exchange (ETDEWEB)

    Fondeur, F.; Fink, S.

    2011-12-08

    The Office of Waste Processing, within the Office of Technology Innovation and Development, is funding the development of an enhanced solvent for deployment at the Savannah River Site for removal of cesium from High Level Waste. For simplicity, this solvent is referred to as the Next Generation Solvent (NGS). The technical effort is collaboration between Oak Ridge National Laboratory (ORNL), Savannah River National Laboratory (SRNL), and Argonne National Laboratory. The initial deployment target envisioned for the technology was within the Modular Caustic-Side Solvent Extraction Unit (MCU). Deployment of a new chemical within an existing facility requires verification that the chemical components are compatible with the installed equipment. In the instance of a new organic solvent, the primary focus is on compatibility of the solvent with polyphenylene sulfide (PPS), the polymer used in the coalescers within MCU. This report provides the data from exposing PPS polymer to NGS. The test was conducted over a three month period. PPS is remarkably stable in the presence of the next generation solvent. Testing showed no indication of swelling or significant leaching. Preferential sorption of the Modifier on PPS was observed but the same behavior occurs with the baseline solvent. Therefore, PPS coalescers exposed to the NGS are expected to perform comparably to those in contact with the baseline solvent.

  17. Electrogenerative leaching of nickel sulfide concentrate with ferric chloride

    Institute of Scientific and Technical Information of China (English)

    王少芬; 方正; 王云燕; 陈阳国

    2004-01-01

    In order to utilize the chemical energy in hydrometallurgical process of sulfide minerals reasonably and to simplify the purifying process, the electrogenerative process was applied and a dual cell system was introduced to investigate FeCl3 leaching of nickel sulfide concentrate. Some factors influencing the electrogenerative leaching, such as electrode structure, temperature and solution concentration were studied. The results show that a certain quantity of electrical energy accompanied with the leached products can be acquired in the electrogenerative leaching process.The output current and power increase with the addition of acetylene black to the electrode. Varying the components of electrode just affects the polarization degree of anode. Increasing FeCl3 concentration results in a sharp increase in the output of the leaching cell when c(FeCl3) is less than 0.1 mol/L. The optimum value of NaCl concentration for electrogenerative leaching nickel sulfide concentrate with FeCl3 is 3.0 mol/L. Temperature influences electrogenerative leaching by affecting anodic and cathodic polarization simultaneously. The apparent activation energy is determined to be 34.63 kJ/mol in the range of 298 K to 322 K. The leaching rate of Ni2+ is 29.3% after FeCl3 electrogenerative leaching of nickel sulfide concentrate for 620 min with a filter bag electrode.

  18. Kinetics of Leaching Calcium from Dolomite

    Directory of Open Access Journals (Sweden)

    Azizi, A.

    2011-06-01

    Full Text Available Magnesia is obtained from magnesite ore and the production process applied should remove accompanying minerals that reduce its refractoriness. Given that magnesite reservoirs are more exploited and largely exhausted, there is a growing need for production of magnesia on the basis of other magnesium minerals. Dolomite is a promising source of magnesia because it forms large deposits, is easy to exploit, and generally contains a small quantity of impurities.The kinetics of calcium leaching from dolomite by magnesium-nitrate solution has been studied. The research program included the influence of temperature, mass fraction of magnesium nitrate in solution, dolomite particle size and leaching time. Time dependence of calcium leaching is described by relevant kinetic equations. Rate coefficients, their temperature dependence and Arrhenius activation energy have been determined.

  19. Experimental study of in situ leaching uranium mining for low permeable sandstone uranium deposits using some surfactant

    International Nuclear Information System (INIS)

    In-situ leaching mining of low-permeable sandstone uranium deposit is difficult in technology now. The application of surfactant to in-situ leaching uranium mining of low permeable sandstone uranium deposit was studied using agitation leaching and column leaching for some uranium deposit in Xinjiang, China. The leaching solutions were adopted 10 g/L H2SO4 with different concentrations of the surfactant P. The results from agitation leaching experiments show that adding surfactant P can enhance the leaching rate, and the leaching rate of uranium reaches the highest which is 92.6% at 10 mg/L surfactant P. The results of column leaching show that the hydraulic conductivity of ore was increased by 28.8%, and the leaching rate of uranium was increased by 32% which reached 85.79%, when the leaching solutions were added 10 mg/L surfactant P. The surfactant decreases the surface tension of solution, which further increases the wetting capacity of solution to ore,so the adding of surfactant P could promote the leaching of uranium and increase the leaching rate. For low permeable sandstone uranium deposit, the in-situ leaching mining may be operated through adding suitable surfactant into leaching solutions. (authors)

  20. Soil column leaching of pesticides.

    Science.gov (United States)

    Katagi, Toshiyuki

    2013-01-01

    In this review, I address the practical and theoretical aspects of pesticide soil mobility.I also address the methods used to measure mobility, and the factors that influence it, and I summarize the data that have been published on the column leaching of pesticides.Pesticides that enter the unsaturated soil profile are transported downwards by the water flux, and are adsorbed, desorbed, and/or degraded as they pass through the soil. The rate of passage of a pesticide through the soil depends on the properties of the pesticide, the properties of the soil and the prevailing environmental conditions.Because large amounts of many different pesticides are used around the world, they and their degradates may sometimes contaminate groundwater at unacceptable levels.It is for this reason that assessing the transport behavior and soil mobility of pesticides before they are sold into commerce is important and is one indispensable element that regulators use to assess probable pesticide safety. Both elementary soil column leaching and sophisticated outdoor lysimeter studies are performed to measure the leaching potential for pesticides; the latter approach more reliably reflects probable field behavior, but the former is useful to initially profile a pesticide for soil mobility potential.Soil is physically heterogeneous. The structure of soil varies both vertically and laterally, and this variability affects the complex flow of water through the soil profile, making it difficult to predict with accuracy. In addition, macropores exist in soils and further add to the complexity of how water flow occurs. The degree to which soil is tilled, the density of vegetation on the surface, and the type and amounts of organic soil amendments that are added to soil further affect the movement rate of water through soil, the character of soil adsorption sites and the microbial populations that exist in the soil. Parameters that most influence the rate of pesticide mobility in soil are

  1. In-situ uranium leaching

    International Nuclear Information System (INIS)

    This invention provides a method for improving the recovery of mineral values from ore bodies subjected to in-situ leaching by controlling the flow behaviour of the leaching solution. In particular, the invention relates to an in-situ leaching operation employing a foam for mobility control of the leaching solution. A foam bank is either introduced into the ore bed or developed in-situ in the ore bed. The foam then becomes a diverting agent forcing the leaching fluid through the previously non-contacted regions of the deposit

  2. Statistics of Caustics in Large-Scale Structure Formation

    Science.gov (United States)

    Feldbrugge, Job L.; Hidding, Johan; van de Weygaert, Rien

    2016-10-01

    The cosmic web is a complex spatial pattern of walls, filaments, cluster nodes and underdense void regions. It emerged through gravitational amplification from the Gaussian primordial density field. Here we infer analytical expressions for the spatial statistics of caustics in the evolving large-scale mass distribution. In our analysis, following the quasi-linear Zel'dovich formalism and confined to the 1D and 2D situation, we compute number density and correlation properties of caustics in cosmic density fields that evolve from Gaussian primordial conditions. The analysis can be straightforwardly extended to the 3D situation. We moreover, are currently extending the approach to the non-linear regime of structure formation by including higher order Lagrangian approximations and Lagrangian effective field theory.

  3. Statistics of Caustics in Large-Scale Structure Formation

    CERN Document Server

    Feldbrugge, Job; van de Weygaert, Rien

    2014-01-01

    The cosmic web is a complex spatial pattern of walls, filaments, cluster nodes and underdense void regions. It emerged through gravitational amplification from the Gaussian primordial density field. Here we infer analytical expressions for the spatial statistics of caustics in the evolving large-scale mass distribution. In our analysis, following the quasi-linear Zeldovich formalism and confined to the 1D and 2D situation, we compute number density and correlation properties of caustics in cosmic density fields that evolve from Gaussian primordial conditions. The analysis can be straightforwardly extended to the 3D situation. We moreover, are currently extending the approach to the non-linear regime of structure formation by including higher order Lagrangian approximations and Lagrangian effective field theory.

  4. Practical procedure for coma-free alignment using caustic figure

    International Nuclear Information System (INIS)

    The practical procedure for coma-free alignment using a single defocused transmission electron microscopy (TEM) image is presented. Caustic figures observed in the defocused TEM image of a focused probe are utilized. Coma-free alignment can be carried out by coinciding a bright-field spot with the center of a caustic curve as observed in an underfocus TEM image. With this method, beam tilt misalignment is reduced to the sub-mrad order (e.g. 0.3 mrad for 300 kV FEG-TEM). This can be done without intentional beam tilting, an amorphous specimen, high-resolution TEM images, or fast Fourier transform for diffractogram or cross-correlation, which are used in previous methods. Residual coma aberration is detected using the multiple Bragg images of a known crystal. Similarity between the present coma-free alignment and well-known STEM alignment using shadow image is discussed

  5. Caustics and Intermittency in Turbulent Suspensions of Heavy Particles

    CERN Document Server

    Bec, J; Cencini, M; Lanotte, A S; Toschi, F

    2009-01-01

    The statistics of velocity differences between very heavy inertial particles suspended in an incompressible turbulent flow is found to be extremely intermittent. When particles are separated by distances within the viscous subrange, the competition between quiet regular regions and multi-valued caustics leads to a quasi bi-fractal behavior of the particle velocity structure functions, with high-order moments bringing the statistical signature of caustics. Contrastingly, for particles separated by inertial-range distances, the velocity-difference statistics is characterized in terms of a local H\\"{o}lder exponent, which is a function of the scale-dependent particle Stokes number only. Results are supported by high-resolution direct numerical simulations. It is argued that these findings might have implications in the early stage of rain droplets formation in warm clouds.

  6. Study of the relation between hydrated portland cement composition and leaching resistance

    NARCIS (Netherlands)

    Eijk, van R.J.; Brouwers, H.J.H.

    1998-01-01

    The present paper addresses cement compositions that have an optimal resistance against acid attack and hence, low leaching rates and optimal waste containment. To this end a shrinking core leaching model is used that describes the leaching of metals from a cement sample. This process is directly re

  7. Caustic ingestion injuries-at military hospital rawalpindi

    International Nuclear Information System (INIS)

    To study the pattern and endoscopic severity of caustic ingestion injuries presenting at Military Hospital Rawalpindi. Study Design: Descriptive study. Place and Duration of Study: The study was conducted at Medical and Gastroenterology Department Military Hospital Rawalpindi from August 2012 to April 2013. Material and Methods: Patients were selected from those who presented with caustic ingestion history in Medical OPD, ER and in medical wards. After informed consent the patient underwent upper gastrointestinal (GI) Endoscopy. Endoscopic findings were recorded. Results: Out of 50 patients, 21(42%) were males and 29 (58%) were females. Ingestion was accidental in 19 (38%) and was with intent of suicide or self-harm in 31(62%) patients. Mean age was 33.2 years (SD ± 13.2). All the patients were subjected to upper GI endoscopy and findings were recorded. Endoscopic findings were grade 0 in 4 (8%), Grade 1 in 6 (12%), grade 2a in 7 (14%), grade 2b in 10 (20%), grade 3a in 6 (12%) and grade 3b in 17 (34%) patients. Conclusion: Caustic ingestion injuries were seen more in younger females with predominant cause as suicidal intent. On endoscopic examination severe corrosive injuries were more frequent. (author)

  8. A middle age addicted man with caustic stomach

    Directory of Open Access Journals (Sweden)

    Gholamreza Nouri Broujerdi

    2014-06-01

    Full Text Available Background: The term caustic generally refers to alkaline and the term corrosive generally refers to acidic agents' injury; however, in medical literature caustic is frequently a term applied to both substances. Ingested alkali typically damage the esophagus more than stomach or duodenum, whereas acids usually cause more severe gastric injury. Since esophagus has a slightly alkaline pH, its epithelium is more resistant to acids, so that only 6 to 20% of those who ingest these substances present lesions in this organ. Case : A middle-aged addicted man who drunk hydrochloric acid accidentally had extensive necrosis of the stomach with remarkable sparing of the esophagus on second look exploration. A total gastrectomy with a Roux-en-Y esophago-jejunostomy with feeding jejunostomy was performed. Conclusion : In caustic GI injury, patients who are operated on and found to have no evidence of extensive esophago-gastric necrosis, a biopsy of the posterior gastric wall should be performed to exclude occult injury. If histologically there is a question of viability, a second look operation should be performed within 36 hours.

  9. Analysis of ray stability and caustic formation in a layered moving fluid medium

    CERN Document Server

    Bergman, David R

    2015-01-01

    Caustic formation occurs within a ray skeleton as optical or acoustic fields propagate in a medium with variable refractive properties and are unphysical, their presence being an artifact of the ray approximation of the field, and methods of correcting the field near a caustic are well known. Differential geometry provides a novel approach to calculating acoustic intensity, assessing ray stability and locating caustics in acoustic ray traces when the properties of medium are completely arbitrary by identifying points on the caustic with conjugate points along various rays. The method of geodesic deviation is applied to the problem of determining ray stability and locating caustics in 2-dimensional acoustic ray traces in a layered moving medium. Specifically, a general treatment of caustic formation in sound ducts and in piecewise continuous media is presented and applied to various idealized and realistic scenarios.

  10. Dynamics of aluminum leaching from water purification sludge.

    Science.gov (United States)

    Cheng, Wen-Po; Fu, Chi-Hua; Chen, Ping-Hung; Yu, Ruey-Fang

    2012-05-30

    In this investigation, the shrinking core model is used to study the rate of aluminum salt leaching from water purification sludge (WPS). This model, which describes the aluminum leaching rate, can be developed to maximize the Al(III) recovering efficiency. Laboratory results indicate that when the mixing speed exceeds 80rpm, the effect of film diffusion control on the leaching process is greatly reduced, such that any further increase in the mixing speed does not affect the Al(III) leaching rate. Additionally, increasing the temperature or acid concentration improves Al(III) leaching rate. The laboratory data were verified by using the shrinking core model to confirm that the leaching of Al(III) from WPS is consistent with the inert-layer diffusion control model. This finding reveals that large amounts of SiO(2), Al(2)O(3) and other inert constituents will form an inter diffusion layer in the WPS and thus become the major limiting factors that control the Al(III) leaching process. The dynamic equation can be expressed as 1-3(1-x)(2/3)+2(1-x)=(2707.3 exp(-3887.6/T))t, in which the apparent activation energy and pre-exponential factors are 32.32 kJ/mol and 2707.3 min(-1), respectively, as determined by solving the Arrhenius equation.

  11. Defense High-Level Waste Leaching Mechanisms Program. Final report

    International Nuclear Information System (INIS)

    The Defense High-Level Waste Leaching Mechanisms Program brought six major US laboratories together for three years of cooperative research. The participants reached a consensus that solubility of the leached glass species, particularly solubility in the altered surface layer, is the dominant factor controlling the leaching behavior of defense waste glass in a system in which the flow of leachant is constrained, as it will be in a deep geologic repository. Also, once the surface of waste glass is contacted by ground water, the kinetics of establishing solubility control are relatively rapid. The concentrations of leached species reach saturation, or steady-state concentrations, within a few months to a year at 70 to 900C. Thus, reaction kinetics, which were the main subject of earlier leaching mechanisms studies, are now shown to assume much less importance. The dominance of solubility means that the leach rate is, in fact, directly proportional to ground water flow rate. Doubling the flow rate doubles the effective leach rate. This relationship is expected to obtain in most, if not all, repository situations

  12. Defense High-Level Waste Leaching Mechanisms Program. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Mendel, J.E. (compiler)

    1984-08-01

    The Defense High-Level Waste Leaching Mechanisms Program brought six major US laboratories together for three years of cooperative research. The participants reached a consensus that solubility of the leached glass species, particularly solubility in the altered surface layer, is the dominant factor controlling the leaching behavior of defense waste glass in a system in which the flow of leachant is constrained, as it will be in a deep geologic repository. Also, once the surface of waste glass is contacted by ground water, the kinetics of establishing solubility control are relatively rapid. The concentrations of leached species reach saturation, or steady-state concentrations, within a few months to a year at 70 to 90/sup 0/C. Thus, reaction kinetics, which were the main subject of earlier leaching mechanisms studies, are now shown to assume much less importance. The dominance of solubility means that the leach rate is, in fact, directly proportional to ground water flow rate. Doubling the flow rate doubles the effective leach rate. This relationship is expected to obtain in most, if not all, repository situations.

  13. Leaching from solidified waste forms under saturated and unsaturated conditions

    International Nuclear Information System (INIS)

    The leaching behavior of nitrate ion from a cement based waste form containing low-level radioactive waste was shown to be identical under saturated and unsaturated soil conditions. Only in soils containing less than 2 wt %water did the leach rate decrease. The observation of identical leach rates under saturated and unsaturated conditions is explained by diffusion through the waste form being the limiting step. Diffusion through the soil decreases in very dry soil and the limiting step changes. These laboratory tests were verified by measurements on similar, Portland cement based waste form in a field lysimeter

  14. Modeling of Boehmite Leaching from Actual Hanford High-Level Waste Samples

    International Nuclear Information System (INIS)

    The U.S. Department of Energy plans to vitrify approximately 60,000 metric tons of high-level waste (HLW) sludge from underground storage tanks at the Hanford Site in Southwest Washington State. To reduce the volume of HLW requiring treatment, a goal has been set to remove a significant quantity of the aluminum, which comprises nearly 70 percent of the sludge. Aluminum is found in the form of gibbsite and sodium aluminate, which can be easily dissolved by washing the waste stream with caustic, and boehmite, which comprises nearly half of the total aluminum, but is more resistant to caustic dissolution and requires higher treatment temperatures and hydroxide concentrations. Chromium, which makes up a much smaller amount (∼3%) of the sludge, must also be removed because there is a low tolerance for chromium in the HLW immobilization process. In this work, the coupled dissolution kinetics of aluminum and chromium species during caustic leaching of actual Hanford HLW samples is examined. The experimental results are used to develop a model that provides a basis for predicting dissolution dynamics from known process temperature and hydroxide concentration. (authors)

  15. Modelling the Long Term Leaching Behaviour of 137CS from Different Stabilized Waste Matrices

    International Nuclear Information System (INIS)

    Leaching characteristics of ''1''3''7Cs from immobilized waste matrices in different cement-based grouts have been assessed to investigate the influence of the additives on the leaching behavior of the solid waste matrices. The International Atomic Energy's Agency (IAEA) standard leach method has been employed to study the leach pattern of 137Cs radionuclide from the immobilized waste form. The examination of the leaching data revealed that clay additives reduces the leach rate for the studied radionuclide. The controlling leaching mechanism has been studied and the transport parameters were calculated for all studied waste matrices. Simplified analytical models have been derived to predict the Cumulative Leach Fraction (CLF) of radionuclides over the studied experimental period. These simplified research models could be used as a screening tool to assess the performance of the waste matrix under repository conditions. (author)

  16. C-106 High-Level Waste Solids: Washing/Leaching and Solubility Versus Temperature Studies

    Energy Technology Data Exchange (ETDEWEB)

    GJ Lumetta; DJ Bates; PK Berry; JP Bramson; LP Darnell; OT Farmer III; LR Greenwood; FV Hoopes; RC Lettau; GF Piepel; CZ Soderquist; MJ Steele; RT Steele; MW Urie; JJ Wagner

    2000-01-26

    This report describes the results of a test conducted by Battelle to assess the effects of inhibited water washing and caustic leaching on the composition of the Hanford tank C-106 high-level waste (HLW) solids. The objective of this work was to determine the composition of the C-106 solids remaining after washing with 0.01M NaOH or leaching with 3M NaOH. Another objective of this test was to determine the solubility of various C-106 components as a function of temperature. The work was conducted according to test plan BNFL-TP-29953-8,Rev. 0, Determination of the Solubility of HLW Sludge Solids. The test went according to plan, with only minor deviations from the test plan. The deviations from the test plan are discussed in the experimental section.

  17. Leaching of Pyrites of Various Reactivities by Thiobacillus ferrooxidans

    OpenAIRE

    Baldi, Franco; Clark, Thomas; Pollack, S. S.; Olson, Gregory J.

    1992-01-01

    Wide variations were found in the rate of chemical and microbiological leaching of iron from pyritic materials from various sources. Thiobacillus ferrooxidans accelerated leaching of iron from all of the pyritic materials tested in shake flask suspensions at loadings of 0.4% (wt/vol) pulp density. The most chemically reactive pyrites exhibited the fastest bioleaching rates. However, at 2.0% pulp density, a delay in onset of bioleaching occurred with two of the pyrites derived from coal source...

  18. STATISTICS OF MICROLENSING CAUSTIC CROSSINGS IN Q 2237+0305: PECULIAR VELOCITY OF THE LENS GALAXY AND ACCRETION DISK SIZE

    Energy Technology Data Exchange (ETDEWEB)

    Mediavilla, E. [Instituto de Astrofísica de Canarias, Vía Láctea S/N, La Laguna E-38200 Tenerife (Spain); Jimenez-Vicente, J. [Departamento de Física Teórica y del Cosmos, Universidad de Granada, Campus de Fuentenueva E-18071 Granada (Spain); Muñoz, J. A. [Departamento de Astronomía y Astrofísica, Universidad de Valencia E-46100 Burjassot, Valencia (Spain); Mediavilla, T.; Ariza, O. [Departamento de Estadística e Investigación Operativa, Universidad de Cádiz, Avda Ramón Puyol s/n E-11202, Algeciras, Cádiz (Spain)

    2015-01-10

    We use the statistics of caustic crossings induced by microlensing in the lens system Q 2237+0305 to study the lens galaxy peculiar velocity. We calculate the caustic crossing rates for a comprehensive family of stellar mass functions and find a dependence of the average number of caustic crossings with the effective transverse velocity and the average mass, 〈n〉∝v{sub eff}/√(〈m〉), equivalent to the theoretical prediction for the case of microlenses with identical masses. We explore the possibilities of the method to measure v {sub eff} using the ∼12 yr of Optical Gravitational Lensing Experiment monitoring of the four images of Q 2237+0305. To determine a lower limit for v {sub eff}, we count, conservatively, a single caustic crossing for each one of the four high magnification events identified in the literature (plus one additional proposed by us) obtaining v{sub eff}≳240√(〈m〉/0.17 M{sub ⊙}) km s{sup −1} at 68% of confidence. From this value and the average FWHM of the four high magnification events, we obtain a lower limit of r{sub s}≳1.4√(〈m〉/0.17 M{sub ⊙}) light-days for the radius of the source (r{sub s} = FWHM/2.35). Tentative identification of three additional caustic crossing events leads to estimates of v{sub eff}≃(493±246)√(〈m〉/0.17 M{sub ⊙}) km s{sup −1} for the effective transverse velocity and of r{sub s}≃(2.7±1.3)√(〈m〉/0.17 M{sub ⊙}) light-days for the source size. The estimated transverse peculiar velocity of the galaxy is v{sub t}≃(429±246)√(〈m〉/0.17 M{sub ⊙}) km s{sup −1}.

  19. Improving hydrolysis of food waste in a leach bed reactor

    International Nuclear Information System (INIS)

    Highlights: • This paper assesses leaching of food waste in a two phase digestion system. • Leaching is assessed with and without an upflow anaerobic sludge blanket (UASB). • Without the UASB, low pH reduces hydrolysis, while increased flows increase leaching. • Inclusion of the UASB increases pH to optimal levels and greatly improves leaching. • The optimal conditions are suggested as low flow with connection to the UASB. - Abstract: This paper examines the rate of degradation of food waste in a leach bed reactor (LBR) under four different operating conditions. The effects of leachate recirculation at a low and high flow rate are examined with and without connection to an upflow anaerobic sludge blanket (UASB). Two dilution rates of the effective volume of the leach bed reactors were investigated: 1 and 6 dilutions per LBR per day. The increase in dilution rate from 1 to 6 improved the destruction of volatile solids without connection to the UASB. However connection to the UASB greatly improved the destruction of volatile solids (by almost 60%) at the low recirculation rate of 1 dilution per day. The increase in volatile solids destruction with connection to the UASB was attributed to an increase in leachate pH and buffering capacity provided by recirculated effluent from the UASB to the leach beds. The destruction of volatile solids for both the low and high dilution rates was similar with connection to the UASB, giving 82% and 88% volatile solids destruction respectively. This suggests that the most efficient leaching condition is 1 dilution per day with connection to the UASB

  20. Improving hydrolysis of food waste in a leach bed reactor

    Energy Technology Data Exchange (ETDEWEB)

    Browne, James D.; Allen, Eoin; Murphy, Jerry D., E-mail: jerry.murphy@ucc.ie

    2013-11-15

    Highlights: • This paper assesses leaching of food waste in a two phase digestion system. • Leaching is assessed with and without an upflow anaerobic sludge blanket (UASB). • Without the UASB, low pH reduces hydrolysis, while increased flows increase leaching. • Inclusion of the UASB increases pH to optimal levels and greatly improves leaching. • The optimal conditions are suggested as low flow with connection to the UASB. - Abstract: This paper examines the rate of degradation of food waste in a leach bed reactor (LBR) under four different operating conditions. The effects of leachate recirculation at a low and high flow rate are examined with and without connection to an upflow anaerobic sludge blanket (UASB). Two dilution rates of the effective volume of the leach bed reactors were investigated: 1 and 6 dilutions per LBR per day. The increase in dilution rate from 1 to 6 improved the destruction of volatile solids without connection to the UASB. However connection to the UASB greatly improved the destruction of volatile solids (by almost 60%) at the low recirculation rate of 1 dilution per day. The increase in volatile solids destruction with connection to the UASB was attributed to an increase in leachate pH and buffering capacity provided by recirculated effluent from the UASB to the leach beds. The destruction of volatile solids for both the low and high dilution rates was similar with connection to the UASB, giving 82% and 88% volatile solids destruction respectively. This suggests that the most efficient leaching condition is 1 dilution per day with connection to the UASB.

  1. Complex Leaching Process of Scheelite in Hydrochloric and Phosphoric Solutions

    Science.gov (United States)

    Liu, Liang; Xue, Jilai; Liu, Kang; Zhu, Jun; Wang, Zengjie

    2016-09-01

    The complex leaching process of synthetic scheelite and scheelite concentrate in hydrochloric and phosphoric solutions has been investigated for improving process efficiency. A higher leaching rate, compared with the classic acid leaching process, can be obtained through the synergy of HCl and H3PO4 with appropriate W/P mole ratio, temperature, and acid concentration. For synthetic scheelite, the optimum leaching conditions were W/P mole ratio 7:1, temperature 50°C, HCl 0.72 mol/L, and stirring speed 600 rpm; for scheelite concentrate, W/P mole ratio 7:1, temperature 80°C, HCl 2.16 mol/L, and stirring speed 1000 rpm. The leaching rates under the optimized conditions can reach up to 98% or even higher. FTIR spectra analysis confirmed that the leachate composition remained as H3[PW12O40] in the range of varying W/P mole ratios, so the PO4 3- in acidic solution and phosphorus content in the leaching product could be better controlled. The function 1 - (1 - X)1/3 against leaching time was applied to fit the experimental data, and the apparent activation energy, E a, was calculated as 60.65 kJ/mol. The results would be valuable for effectively using scheelite as a raw material resource for sustainable tungsten production.

  2. Leaching Test Relationships, Laboratory-to-Field Comparisons and Recommendations for Leaching Evaluation using the Leaching Environmental Assessment Framework (LEAF)

    Science.gov (United States)

    This report presents examples of the relationships between the results of laboratory leaching tests, as defined by the Leaching Environmental Assessment Framework (LEAF) or analogous international test methods, and leaching of constituents from a broad range of materials under di...

  3. Spectral caustics in laser assisted Breit-Wheeler process

    CERN Document Server

    Nousch, T; Kämpfer, B; Titov, A I

    2015-01-01

    Electron-positron pair production by the Breit-Wheeler process embedded in a strong laser pulse is analyzed. The transverse momentum spectrum displays prominent peaks which are interpreted as caustics, the positions of which are accessible by the stationary phases. Examples are given for the superposition of an XFEL beam with an optical high-intensity laser beam. Such a configuration is available, e.g., at LCLS at present and at European XFEL in near future. It requires a counter propagating probe photon beam with high energy which can be generated by synchronized inverse Compton backscattering.

  4. Spectral caustics in laser assisted Breit-Wheeler process

    Science.gov (United States)

    Nousch, T.; Seipt, D.; Kämpfer, B.; Titov, A. I.

    2016-04-01

    Electron-positron pair production by the Breit-Wheeler process embedded in a strong laser pulse is analyzed. The transverse momentum spectrum displays prominent peaks which are interpreted as caustics, the positions of which are accessible by the stationary phases. Examples are given for the superposition of an XFEL beam with an optical high-intensity laser beam. Such a configuration is available, e.g., at LCLS at present and at European XFEL in near future. It requires a counter propagating probe photon beam with high energy which can be generated by synchronized inverse Compton backscattering.

  5. Eikonal waves, caustics and mode conversion in tokamak plasmas

    Science.gov (United States)

    Jaun, A.; Tracy, E. R.; Kaufman, A. N.

    2007-01-01

    Ray optics is used to model the propagation of short electromagnetic plasma waves in toroidal geometry. The new RAYCON code evolves each ray independently in phase space, together with its amplitude, phase and focusing tensor to describe the transport of power along the ray. Particular emphasis is laid on caustics and mode conversion layers, where a linear phenomenon splits a single incoming ray into two. The complete mode conversion algorithm is described and tested for the first time, using the two space dimensions that are relevant in a tokamak. Applications are shown, using a cold plasma model to account for mode conversion at the ion-hybrid resonance in the Joint European Torus.

  6. Spectral caustics in laser assisted Breit–Wheeler process

    Directory of Open Access Journals (Sweden)

    T. Nousch

    2016-04-01

    Full Text Available Electron–positron pair production by the Breit–Wheeler process embedded in a strong laser pulse is analyzed. The transverse momentum spectrum displays prominent peaks which are interpreted as caustics, the positions of which are accessible by the stationary phases. Examples are given for the superposition of an XFEL beam with an optical high-intensity laser beam. Such a configuration is available, e.g., at LCLS at present and at European XFEL in near future. It requires a counter propagating probe photon beam with high energy which can be generated by synchronized inverse Compton backscattering.

  7. 16 CFR 1500.129 - Substances named in the Federal Caustic Poison Act.

    Science.gov (United States)

    2010-01-01

    ... Poison Act. 1500.129 Section 1500.129 Commercial Practices CONSUMER PRODUCT SAFETY COMMISSION FEDERAL... REGULATIONS § 1500.129 Substances named in the Federal Caustic Poison Act. The Commission finds that for those substances covered by the Federal Caustic Poison Act (44 Stat. 1406), the requirements of section 2(p)(1)...

  8. Biological treatment of sulfidic spent caustics under haloalkaline conditions using soda lake bacteria

    NARCIS (Netherlands)

    Graaff, de C.M.

    2012-01-01

    In this thesis, the development of a newbiotechnological process for the treatment of undiluted sulfidic spent caustics (SSC’s) using soda lake bacteria is described. SSC’s are waste solutions that are formed in the oil and gas industry due to the caustic (NaOH) scrubbing of hydrocarbon

  9. Coupling leaching of sphalerite concentrate

    Institute of Scientific and Technical Information of China (English)

    彭鹏; 谢惠琴; 卢立柱

    2004-01-01

    Coupling process of sphalerite concentrate leaching in H2 SO4-HNO3 and tetrachloroethylene extracting of sulfur was investigated. Effects of leaching temperature, leaching time, mass ratio of liquid to solid and tetrachloroethylene addition on zinc leaching processes were examined separately. SEM images of sphalerite concentrate and residues were performed by using JEM-6700F field emission scanning electron microscope. The relationship between the number of recycling and extraction ratio of zinc was studied. The results indicate that 99.6 % zinc is obtained after leaching for 3 h at 85 ℃ and pressure of 0.1 MPa O2, with 20 g sphalerite concentrate in 200 mL leaching solution containing 2.0 mol/L H2SO4 and 0.2 mol/L HNO3, in the presence of 10 mL C2Cl4. The leaching time of zinc is 50% shorter than that in the common leaching. The coupling effect is distinct. The recycled C2Cl4 exerts little influence on extraction ratio of zinc.

  10. Biases and caustics in long-range acoustic tomography

    Science.gov (United States)

    Munk, Walter; Wunsch, Carl

    1985-11-01

    We consider the travel time perturbation δt of acoustic rays in an ocean sound channel. The perturbations arom a straining e(x,z) of the water column. An expansion to second order gives δt ≈ τ + ατ , where and are suitably weighted strain wverages, α is a number of order 1 (except near caustics), and τ is the phase integral (the 'reduced travel time' in the seismic literature); τ is a function of ray steepness and range, and varies from zero for axial rays to order 10 s for steep rays at 1000 km range. The quadratic bais ατ changes sign at the caustics; generally it is negative (warm bias) for a range-dependent ocean as compared to a range-independent ocean with the same average properties. We consider two separate problems: (a) linear inversions for the range-averaged profile in soundspeed (temperature) introduces 0.5 m s -1 (0.1 °C) systematic errors arising from horizontal ocean variability (mesoscal activity), but these errors can be reduced by making corrections for . (b) In the problem of monitoring for climatic changes of large-scale ocean features, the quadratic bias is negligible compared to the sample variability, and there is an inherent advantage to the long-range horizontal integration in acoustic tomography over the traditional local measurements.

  11. Effect of thermal treatment on caustic stress corrosion cracking an chloride SCC of super austenitic stainless steel-S32050

    International Nuclear Information System (INIS)

    This paper focused on the caustic SCC and chloride SCC of super austenitic stainless stee S32050. Thermal treatment (550 .deg. C 15hrs) and high temperature mill annealing (HTMA, 1,250 .deg. C 5min.) did enhance the SCC resistance than mill annealed specimen. It is considered that dislocation array is the most important factor on SCC resistance among some variables such as repassivation rate, residual stress, grain size, yield strength etc. Substituted Mn didn't affec the anodic polarization behavior of Mn-modified S32050, but cold working to the alloys reduced the SCC resistance because of the embrittlement by cold working

  12. Effect of thermal treatment on caustic stress corrosion cracking an chloride SCC of super austenitic stainless steel-S32050

    Energy Technology Data Exchange (ETDEWEB)

    Kim, S. K.; Park, Y. S. [Yonsei Univ., Seoul (Korea, Republic of); Kim, Y. S. [Andong Univ., Andong (Korea, Republic of); Ryu, W. S. [KAERI, Taejon (Korea, Republic of)

    2000-10-01

    This paper focused on the caustic SCC and chloride SCC of super austenitic stainless stee S32050. Thermal treatment (550 .deg. C 15hrs) and high temperature mill annealing (HTMA, 1,250 .deg. C 5min.) did enhance the SCC resistance than mill annealed specimen. It is considered that dislocation array is the most important factor on SCC resistance among some variables such as repassivation rate, residual stress, grain size, yield strength etc. Substituted Mn didn't affec the anodic polarization behavior of Mn-modified S32050, but cold working to the alloys reduced the SCC resistance because of the embrittlement by cold working.

  13. Mathematical modelling in leaching studies of radioactive waste

    International Nuclear Information System (INIS)

    Transport phenomena involved in the leaching of a radioactive material from a composite matrix into surrounding water are investigated using three methods based on theoretical equations. These arc: diffusion equation derived for a plane source model, rate equation for diffusion coupled with a first-order reaction and an empirical method employing a polynomial equation. The obtained results are compared with respect to their applicability to the 60Co and 137Cs leaching data. (author)

  14. Kinetics of Uranium Extraction from Uranium Tailings by Oxidative Leaching

    Science.gov (United States)

    Zhang, Biao; Li, Mi; Zhang, Xiaowen; Huang, Jing

    2016-07-01

    Extraction of uranium from uranium tailings by oxidative leaching with hydrogen peroxide (H2O2) was studied. The effects of various extraction factors were investigated to optimize the dissolution conditions, as well as to determine the leaching kinetic parameters. The behavior of H2O2 in the leaching process was determined through scanning electron microscopy-energy dispersive x-ray spectroscopy (SEM-EDX) and x-ray diffraction analysis of leaching residues. Results suggest that H2O2 can significantly improve uranium extraction by decomposing the complex gangue structures in uranium tailings and by enhancing the reaction rate between uranium phases and the leaching agent. The extraction kinetics expression was changed from 1 - 3(1 - α)2/3 + 2(1 - α) = K 0(H2SO4)-0.14903(S/L)-1.80435( R o)0.20023 e -1670.93/T t ( t ≥ 5) to 1 - 3(1 - α)2/3 + 2(1 - α) = K 0(H2SO4)0.01382(S/L)-1.83275( R o)0.25763 e -1654.59/T t ( t ≥ 5) by the addition of H2O2 in the leaching process. The use of H2O2 in uranium leaching may help in extracting uranium more efficiently and rapidly from low-uranium-containing ores or tailings.

  15. Kinetics of Uranium Extraction from Uranium Tailings by Oxidative Leaching

    Science.gov (United States)

    Zhang, Biao; Li, Mi; Zhang, Xiaowen; Huang, Jing

    2016-05-01

    Extraction of uranium from uranium tailings by oxidative leaching with hydrogen peroxide (H2O2) was studied. The effects of various extraction factors were investigated to optimize the dissolution conditions, as well as to determine the leaching kinetic parameters. The behavior of H2O2 in the leaching process was determined through scanning electron microscopy-energy dispersive x-ray spectroscopy (SEM-EDX) and x-ray diffraction analysis of leaching residues. Results suggest that H2O2 can significantly improve uranium extraction by decomposing the complex gangue structures in uranium tailings and by enhancing the reaction rate between uranium phases and the leaching agent. The extraction kinetics expression was changed from 1 - 3(1 - α)2/3 + 2(1 - α) = K 0(H2SO4)-0.14903(S/L)-1.80435(R o)0.20023 e -1670.93/T t (t ≥ 5) to 1 - 3(1 - α)2/3 + 2(1 - α) = K 0(H2SO4)0.01382(S/L)-1.83275(R o)0.25763 e -1654.59/T t (t ≥ 5) by the addition of H2O2 in the leaching process. The use of H2O2 in uranium leaching may help in extracting uranium more efficiently and rapidly from low-uranium-containing ores or tailings.

  16. Self inhibition of aluminium leaching from coal fly ash by sulfuric acid

    Energy Technology Data Exchange (ETDEWEB)

    Seidel, A.; Sluszny, A.; Shelef, G.; Zimmels, Y. [Technion-Israel Institute of Technology, Haifa (Israel). Dept. of Civil Engineering

    1999-11-01

    Coal fly ash (CFA) produced by power plants in Israel is alkaline and contains aluminium that can be leached by different acids. The mechanism of aluminium leaching from CFA by sulfuric acid was investigated. It was found that higher CFA content, which indicates higher solid to liquid ratio in the leaching suspension, decreases the fraction of aluminium leached by sulfuric acid. This behavior constitutes a new unexplained phenomenon, which could not be explained by analysis of the mass action law of the dissolution reactions, but rather by mass transfer considerations. The leaching process involves a self-inhibition mechanism due to the precipitation of calcium sulfate on the surface and within the CFA particles. The effects of CFA content, acid concentration, temperature, and pre-leaching conditioning, upon leaching rates and yields, were tested.

  17. Self inhibition of aluminium leaching from coal fly ash by sulfuric acid

    Energy Technology Data Exchange (ETDEWEB)

    Seidel, A.; Sluszny, A.; Shelef, G.; Zimmels, Y. (Technion-Israel Institute of Technology, Haifa (Israel). Dept. of Civil Engineering)

    1999-01-01

    Coal fly ash (CFA) produced by power plants in Israel is alkaline and contains aluminium that can be leached by different acids. The mechanism of aluminium leaching from CFA by sulfuric acid was investigated. It was found that higher CFA content, which indicates higher solid to liquid ratio in the leaching suspension, decreases the fraction of aluminium leached by sulfuric acid. This behavior constitutes a new unexplained phenomenon, which could not be explained by analysis of the mass action law of the dissolution reactions, but rather by mass transfer considerations. The leaching process involves a self-inhibition mechanism due to the precipitation of calcium sulfate on the surface and within the CFA particles. The effects of CFA content, acid concentration, temperature, and pre-leaching conditioning, upon leaching rates and yields, were tested.

  18. Experimental research in leaching of copper-bearing tailings enhanced by ultrasonic treatment

    Institute of Scientific and Technical Information of China (English)

    ZHANG Jie; WU Ai-xiang; WANG Yi-ming; CHEN Xue-song

    2008-01-01

    On the basis of an experiment in ultrasonic enhanced ammonia leaching of tailings, the effect of ultrasonic waves on copper dissolution was studied. The mechanism of ultrasonic enhanced tailing leaching was analyzed and a technique of ultrasonic enhanced pipe leaching of tailings was proposed. The results show that tailings with ultrasonic treatment can leach up to 89.5% of Cu, which is 13.5% more than those without the treatment. Ultrasonic technology is capable of improving leaching rates and the overall recovery of tailing leaching. Impact waves and micro jet streams can strip and erode affected surfaces of tailing particles to create new active surfaces and disturbances can intensify mass transfer processes in "dead zones". The technique of ultrasonic enhanced pipe leaching of tailings is a combination of existing agitation enhancement with ultrasonic enhancement and can im-prove mineral recovery.

  19. Leach test of cladding removal waste grout using Hanford groundwater

    Energy Technology Data Exchange (ETDEWEB)

    Serne, R.J.; Martin, W.J.; Legore, V.L.

    1995-09-01

    This report describes laboratory experiments performed during 1986-1990 designed to produce empirical leach rate data for cladding removal waste (CRW) grout. At the completion of the laboratory work, funding was not available for report completion, and only now during final grout closeout activities is the report published. The leach rates serve as inputs to computer codes used in assessing the potential risk from the migration of waste species from disposed grout. This report discusses chemical analyses conducted on samples of CRW grout, and the results of geochemical computer code calculations that help identify mechanisms involved in the leaching process. The semi-infinite solid diffusion model was selected as the most representative model for describing leaching of grouts. The use of this model with empirically derived leach constants yields conservative predictions of waste release rates, provided no significant changes occur in the grout leach processes over long time periods. The test methods included three types of leach tests--the American Nuclear Society (ANS) 16.1 intermittent solution exchange test, a static leach test, and a once-through flow column test. The synthetic CRW used in the tests was prepared in five batches using simulated liquid waste spiked with several radionuclides: iodine ({sup 125}I), carbon ({sup 14}C), technetium ({sup 99}Tc), cesium ({sup 137}Cs), strontium ({sup 85}Sr), americium ({sup 241}Am), and plutonium ({sup 238}Pu). The grout was formed by mixing the simulated liquid waste with dry blend containing Type I and Type II Portland cement, class F fly ash, Indian Red Pottery clay, and calcium hydroxide. The mixture was allowed to set and cure at room temperature in closed containers for at least 46 days before it was tested.

  20. Characterization of solids deposited on the modular caustic-side solvent extraction unit (MCU) coalescer media removed in May and October 2014

    Energy Technology Data Exchange (ETDEWEB)

    Fondeur, F. F. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)

    2015-10-01

    During routine maintenance, the coalescers utilized in the Modular Caustic-Side Solvent Extraction Unit (MCU) processing of Salt Batch 6 and a portion of Salt Batch 7 were sampled and submitted to the Savannah River National Laboratory (SRNL) for characterization, for the purpose of identifying solid phase constituents that may be accumulating in these coalescers. Specifically, two samples were received and characterized: A decontaminated salt solution (DSS) coalescer sample and a strip effluent (SE) coalescer sample. Aliquots of the samples were analyzed by XRD, Fourier Transform Infrared (FTIR) Spectroscopy, SEM, and EDS. Other aliquots of the samples were leached in acid solution, and the leachates were analyzed by ICP-AES. In addition, modeling was performed to provide a basis for comparison of the analytical results.

  1. Leaching behavior of butanedionedioxime as gold ligand

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Butanedionedioxime, a small organic compound with low-toxicity and good chemical stability, has been proposed as an effective gold ligand in gold extraction. The result of experiment shows that: 1) highly effective gold lixiviantcan be composed of butanedionedioxime (BDM) with many oxidants, especially potassium permanganate; 2)in the leaching system of BD M- K M nO4 the suitable Ox/Lig(ratio of oxidants to gold ligands) tange is 0.20 ~ 0. 50, optimally 0.25 ~0.45 at the pH range of 7 ~ 11; 3) BDM-KMnO4 extraction of gold from an oxide ore is similar to cyanide(cyanide-O2)extraction, but the leaching rate of gold by BDM-KMnO4 is faster than that by cyanide-O2; 4) gold may readily be recov-ered by carbon adsorption and zinc precipitation

  2. The use of biochar to reduce nitrogen and potassium leaching from soil cultivated with maize

    Directory of Open Access Journals (Sweden)

    W Widowati

    2014-10-01

    Full Text Available Nutrient leaching is often a problem especially in tropical areas with soil fertility constraints. This study aims to reveal the effect of biochars on leaching and uptake of nitrogen and potassium from degraded soils cultivated with maize. Each of three types of biochar originated from rice husk, wood, and coconut shell, was applied to the soil placed in PVC tube at four rates (0, 15, 30, and 45 t/ha. Maize was then planted in each pot. All pots received urea (135 kg N/ha, SP36 (36 kg P2O5/ha, and KCl (110 kg K2O/ha. Twelve treatments (three biochars and four application rates were arranged in a factorial randomized block design with three replicates. Results of the study showed interaction effects of biochar materials and biochar rates on nitrate leaching (except on day 1 to 30 and potassium, N uptake, and plant growth. On day 1-30, leaching of nitrate and potassium was reduced by biochar application. The lowest nitrate leaching was observed at rate of 45 t /ha of wood biochar, while application of 45 t coconut shell biochar / ha resulted in the highest K leaching. Beside, wood biochar resulted in a similar nitrate leaching with that of coconut shell biochar, but nitrate leaching increased with increasing rate of rice husk biochar on day 30-60. All biochar materials yielded similar potassium leaching at all rates. Application of 45 t rice husk biochar /ha resulted in the best maize growth.

  3. Leaching From Biomass Gasification Residues

    DEFF Research Database (Denmark)

    Allegrini, Elisa; Boldrin, Alessio; Polletini, A.;

    2011-01-01

    with geochemical modelling were carried out both on fresh and aged samples. The results showed that the material is comparable to residues from wood combustion and the leaching behaviour was dominated by Ca-containing minerals and solid solutions. Heavy metals were detected in very low concentrations in the bulk......The aim of the present work is to attain an overall characterization of solid residues from biomass gasification. Besides the determination of chemical and physical properties, the work was focused on the study of leaching behaviour. Compliance and pH-dependence leaching tests coupled...

  4. Investigation of the use of ammonium acetate as an alternative lixiviant in the leaching of malachite ore

    Directory of Open Access Journals (Sweden)

    Künkül Asım

    2013-01-01

    Full Text Available The solutions containing ammonia allow for selective leaching of the copper from a copper ore. In this study, the leaching and kinetics of malachite ore were examined using ammonium acetate solutions as an alternative lixiviant. The effects of some experimental parameters on the leaching of malachite ore were investigated. A kinetic model to represent the effects of these parameters on the leaching rate was developed. It was determined that the leaching rate increased with increasing solution concentration, temperature and stirring speed, and decreasing particle size and solid-to-liquid ratio. It was found that the leaching reaction followed the mixed kinetic control model. The activation energy of this leaching process was determined to be 59.6 kJmol-1. Consequently, it was determined that ammonium acetate solutions could be used as an effective leaching agent for the copper extraction form malachite ore.

  5. Leaching of trace elements from coal solid waste

    International Nuclear Information System (INIS)

    In the present work leaching of ash from coal-fired power plants is described and the elemental analysis of coal, ash and leachates has been performed by neutron activation analysis, atomic absorption spectrometry and ion chromatography. The research concerns precipitator ash from powder-coal fired utilities, desulfurization ash from a dry-scrubbing process and fabric filter ash from a fluidized-bed boiler. Reproducibility of shake tests and column leaching has been studied. In the shake tests a wide range of solid to liquid ratios is applied, which allows extrapolation to column conditions. Column experiments carried out in upflow at a fixed flow-rate of approximately 1 cm per day showed good column performance and proved that equilibrium is reached fairly rapidly. A classification of precipitator ashes with respect to leaching behaviour is given, which allows an estimate of leaching characteristics beforehand. In relation to this variability in coal and ash compositions has been studied. (Auth.)

  6. Sulfuric acid leaching kinetics of South African chromite

    Institute of Scientific and Technical Information of China (English)

    Qing Zhao; Cheng-jun Liu; Pei-yang Shi; Bo Zhang; Mao-fa Jiang; Qing-song Zhang; Ron Zevenhoven; Henrik Saxn

    2015-01-01

    The sulfuric acid leaching kinetics of South African chromite was investigated. The negative influence of a solid product layer constituted of a silicon-rich phase and chromium-rich sulfate was eliminated by crushing the chromite and by selecting proper leaching con-ditions. The dimensionless change in specific surface area and the conversion rate of the chromite were observed to exhibit a proportional re-lationship. A modified shrinking particle model was developed to account for the change in reactive surface area, and the model was fitted to experimental data. The resulting model was observed to describe experimental findings very well. Kinetics analysis revealed that the leach-ing process is controlled by a chemical reaction under the employed experimental conditions and the activation energy of the reaction is 48 kJ·mol–1.

  7. Testing the Caustic Ring Dark Matter Halo Model Against Observations in the Milky Way

    Science.gov (United States)

    Dumas, Julie; Newberg, Heidi Jo; Niedzielski, Bethany; Susser, Adam; Thompson, Jeffery M.; Weiss, Jake; Lewis, Kim M.

    2016-06-01

    One prediction of axion dark matter models is they can form Bose-Einstein condensates and rigid caustic rings as a halo collapses in the non-linear regime. In this thesis, we undertake the first study of a caustic ring model for the Milky Way halo (Duffy & Sikivie 2008), paying particular attention to observational consequences. We first present the formalism for calculating the gravitational acceleration of a caustic ring halo. The caustic ring dark matter theory reproduces a roughly logarithmic halo, with large perturbations near the rings. We show that this halo can reasonably match the known Galactic rotation curve. We are not able to confirm or rule out an association between the positions of the caustic rings and oscillations in the observed rotation curve, due to insufficient rotation curve data. We explore the effects of dark matter caustic rings on dwarf galaxy tidal disruption with N-body simulations. Simulations of the Sagittarius (Sgr) dwarf galaxy in a caustic ring halo potential, with disk and bulge parameters that are tuned to match the Galactic rotation curve, match observations of the Sgr trailing tidal tails as far as 90 kpc from the Galactic center. Like the Navarro-Frenk-White (NFW) halo, they are, however, unable to match the leading tidal tail. None of the caustic, NFW, or triaxial logarithmic halos are able to simultaneously match observations of the leading and trailing arms of the Sagittarius stream. We further show that simulations of dwarf galaxies that move through caustic rings are qualitatively similar to those moving in a logarithmic halo. This research was funded by NSF grant AST 10-09670, the NASA-NY Space Grant, and the American Fellowship from AAUW.

  8. Cement based grouts - longevity laboratory studies: leaching behaviour

    International Nuclear Information System (INIS)

    This report describes a series of laboratory tests carried out to determine the possible leaching behaviour of cement-based grouts in repository environments. A reference high-performance cement-based grout, comprised of Canadian Type 50 (U.S. Type V) Sulphate Resisting Portland Cement, silica fume, potable water and superplasticizer, and a commercially available cement grout were subjected to leaching in distilled water and three simulated groundwaters of different ionic strength. Hardened, monolithic specimens of the grout were leached in static, pulsed-flow and continuous flow conditions at temperatures from 10 degrees C to 150 degrees C for periods of up to 56 days. The changes in concentration of ions in the leachants with time were determined and the changes in the morphology of the surfaces of the grout specimens were examined using electron microscopy. After a review of possible mechanisms of degradation of cement-based materials, the data from these experiments are presented. The data show that the grouts will leach when in contact with water through dissolution of more soluble phases. Comparison of the leaching performance of the two grouts indicates that, while there are some minor differences, they behaved quite similarly. The rate of the leaching processes were found to tend to decrease with time and to be accompanied by precipitation and/or growth of an assemblage of secondary alteration phases (i.e., CaCO3, Mg(OH)2). The mechanisms of leaching depended on the environmental conditions of temperature, groundwater composition and water flow rate. Matrix dissolution occurred. However, in many of the tests leaching was shown to be limited by the precipitated/reaction layers which acted as protective surface coatings. (37 refs.) (au)

  9. Biosorption of Copper Ions by Caustic Treated Waste Baker's Yeast Biomass

    OpenAIRE

    Göksungur, Yekta; ÜREN, Sibel; Güvenç, Ulgar

    2003-01-01

    Waste baker's yeast (Saccharomyces cerevisiae) was used as a biosorbent for Cu+2 biosorption. The yeast cells were treated with caustic soda, ethanol and heat to increase their biosorption capacity. Among the treatment methods used, the highest copper uptake (21.1 mg g-1) was obtained with the caustic treatment of baker's yeast. The effect of initial copper concentration and pH on biosorption for caustic treated yeast was studied. The highest Cu+2 uptake (120.7 mg g-1) was obtained ...

  10. Studying the microlenses mass function from statistical analysis of the caustic concentration

    Energy Technology Data Exchange (ETDEWEB)

    Mediavilla, T; Ariza, O [Departamento de Estadistica e Investigacion Operativa, Universidad de Cadiz, Avda de Ramon Puyol, s/n 11202 Algeciras (Spain); Mediavilla, E [Instituto de Astrofisica de Canarias, Avda Via Lactea s/n, La Laguna (Spain); Munoz, J A, E-mail: teresa.mediavilla@ca.uca.es, E-mail: octavio.ariza@uca.es, E-mail: emg@iac.es [Departamento de Astrofisica y Astronomia, Universidad de Valencia, Burjassot, Valencia (Spain)

    2011-09-22

    The statistical distribution of caustic crossings by the images of a lensed quasar depends on the properties of the distribution of microlenses in the lens galaxy. We use a procedure based in Inverse Polygon Mapping to easily identify the critical and caustic curves generated by a distribution of stars in the lens galaxy. We analyze the statistical distributions of the number of caustic crossings by a pixel size source for several projected mass densities and different mass distributions. We compare the results of simulations with theoretical binomial distributions. Finally we apply this method to the study of the stellar mass distribution in the lens galaxy of QSO 2237+0305.

  11. A Systematic Analysis of Caustic Methods for Galaxy Cluster Masses

    CERN Document Server

    Gifford, Daniel; Kern, Nicholas

    2013-01-01

    We quantify the expected observed statistical and systematic uncertainties of the escape velocity as a measure of the gravitational potential and total mass of galaxy clusters. We focus our attention on low redshift (z 25, the scatter in the escape velocity mass is dominated by projections along the line-of-sight. Algorithmic uncertainties from the determination of the projected escape velocity profile are negligible. We quantify how target selection based on magnitude, color, and projected radial separation can induce small additional biases into the escape velocity masses. Using N_gal = 150 (25), the caustic technique has a per cluster scatter in ln(M|M_200) of 0.3 (0.5) and bias 1+/-3% (16+/-5%) for clusters with masses > 10^14M_solar at z<0.15.

  12. Intragranular porosity in Hanford sand grains after reaction with caustic tank wastes: Quantification and implications for reactive transport

    Science.gov (United States)

    Crandell, L. E.; Peters, C. A.; Um, W.; Jones, K. W.; Lindquist, W. B.

    2011-12-01

    Reactions of caustic tank waste with sediments in the 200 East Area of the Hanford site cause quartz and primary aluminosilicate minerals to dissolve. Secondary minerals of sodalite and cancrinite have been shown to nucleate on, and cement together, quartz grains. These secondary precipitates have been found to uptake radionuclides in their network of channels and cages. In this work, thin sections from unreacted and reacted column experiments packed with Hanford sand grains were imaged using 2D Scanning Electron Microscopy (SEM). SEM image analysis reveals large amounts of intragranular pore space in both the reacted and unreacted sands. Grayscale Backscattered Electron (BSE) images were thresholded to separate grain and pore pixels. To quantify the amount of intragranular pore space, a set of images were manually created with the intragranular pore space removed, or the grains filled-in. Porosity, and intragranular porosity, was determined by counting and comparing the number of pore pixels in each pair of images. Intragranular pore space accounts for up to 14% of total porosity. Quartz dissolution in intragranular regions increases the proportion of intragranular pore space in reacted samples. Diffusion of tank waste into these free silica rich areas provides a favorable environment for cancrinite precipitates to form and a potential significant trapping mechanism for radionuclides. Part of this work was to quantify where, within a single pore and a network of pores, precipitation occurred. While the bulk amount of cancrinite precipitation occurred on grain surfaces, cancrinite precipitates were also found in intragranular pore spaces. Up to 10% of total precipitation occurred in intragranular pore space. However, as the system recovers and clean water flow returns, radionuclides incorporated into precipitates in intragranular regions may act as a secondary long term leaching source for contaminants. To determine the trapping or leaching potential from

  13. Leaching of Silver from Boorchi Ag-Pb Ore in Mongolia with Acidic Thiourea Solution

    Institute of Scientific and Technical Information of China (English)

    Nyamdelger Shirchinnamjil; 杨超; 方兆珩

    2008-01-01

    A hydrometalhirgical process to extract silver from the silver-lead ore in Boorchi, Mongolia by using thiourealeaching solution is studied in this work. Through the observation of optical and scanning electron microscopes, and energyspectral analysis, it is determined that 5 kinds of silver minerals exist in the ore, including argentite, Ag-tetrahedrite,Ag-Zn-Sb-tetrahedrite, freibergite and acanthite. The experimental results of direct thiourea leaching of the ore show that56%~60% of silver is leached. The main reason for the low leaching rate is due to silver minerals enveloped in galena andother minerals, even though the ore is ground to the particle size of 75 μm. When the ore is pretreated with ammoniumcarbonate solution under oxidation, the experimental results of thiourea leaching show that the leaching rate of silver increasesto near 75% with the pretreatment. Based on the leaching experiments, a principle hydrometallurgical technological route toextract silver from the Ag-Pb ore is proposed.

  14. Leaching characteristics of heavy metals and brominated flame retardants from waste printed circuit boards

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Xiaoyu [State Environmental Protection Key Laboratory of Environmental Risk Assessment and Control on Chemical Process, East China University of Science and Technology, Shanghai 200237 (China); Guo, Jie, E-mail: guojie@ecust.edu.cn [State Environmental Protection Key Laboratory of Environmental Risk Assessment and Control on Chemical Process, East China University of Science and Technology, Shanghai 200237 (China); Lin, Kuangfei [State Environmental Protection Key Laboratory of Environmental Risk Assessment and Control on Chemical Process, East China University of Science and Technology, Shanghai 200237 (China); Shanghai Key Laboratory of Functional Materials Chemistry, East China University of Science and Technology, Shanghai 200237 (China); Huang, Kai; Deng, Jingjing [State Environmental Protection Key Laboratory of Environmental Risk Assessment and Control on Chemical Process, East China University of Science and Technology, Shanghai 200237 (China)

    2013-02-15

    Highlights: ► Cu and Pb were the most leachable heavy metals in WPCBs according to TCLP and SPLP. ► Penta-BDE congeners were dominated in all extracts. ► High dissolved organic matter condition promoted the BFRs leaching rate. ► Leaching from WPCBs was a significant emission source of BFRs in landfill. -- Abstract: Leaching assessment on five heavy metals (copper, zinc, lead, nickel and cadmium) and two brominated flame retardants (BFRs), polybrominated diphenyl ethers (PBDEs) and tetrabromobisphenol A (TBBPA), from waste printed circuit boards (WPCBs) were conducted using various leaching methods. The mean leaching concentrations of copper were the highest in both toxicity characteristic leaching procedures (TCLP) and synthetic precipitation leaching procedures (SPLP) tests at 8.6 mg/L and 1.1 mg/L, while only lead (6.2 mg/L) exceeded the TCLP criteria and Chinese EPA regulatory limit (both 5.0 mg/L). However, PBDEs and TBBPA were not detected in TCLP and SPLP tests. Then the BFRs leaching trends and potential leachabilities were further investigated in actual landfill leachates using a modified method. Leaching characteristics that fast-leaching initially followed by slow-desorption over time were generally observed. In landfill leachate tests, the highest leaching concentrations of PBDEs and TBBPA were determined at 30.39 and 12.27 μg/L. Meanwhile, the highest leaching rates were estimated to reach 0.08% and 1.00%, respectively, which were significantly influenced by the dissolved organic carbon contents of extracts, the hydrophobicities of target BFRs and the specific surface areas of WPCBs materials. These results proved that leaching from WPCBs was a significant emission source of BFRs in landfill and electronic waste recycling dumpsite.

  15. Leaching characteristics of heavy metals and brominated flame retardants from waste printed circuit boards

    International Nuclear Information System (INIS)

    Highlights: ► Cu and Pb were the most leachable heavy metals in WPCBs according to TCLP and SPLP. ► Penta-BDE congeners were dominated in all extracts. ► High dissolved organic matter condition promoted the BFRs leaching rate. ► Leaching from WPCBs was a significant emission source of BFRs in landfill. -- Abstract: Leaching assessment on five heavy metals (copper, zinc, lead, nickel and cadmium) and two brominated flame retardants (BFRs), polybrominated diphenyl ethers (PBDEs) and tetrabromobisphenol A (TBBPA), from waste printed circuit boards (WPCBs) were conducted using various leaching methods. The mean leaching concentrations of copper were the highest in both toxicity characteristic leaching procedures (TCLP) and synthetic precipitation leaching procedures (SPLP) tests at 8.6 mg/L and 1.1 mg/L, while only lead (6.2 mg/L) exceeded the TCLP criteria and Chinese EPA regulatory limit (both 5.0 mg/L). However, PBDEs and TBBPA were not detected in TCLP and SPLP tests. Then the BFRs leaching trends and potential leachabilities were further investigated in actual landfill leachates using a modified method. Leaching characteristics that fast-leaching initially followed by slow-desorption over time were generally observed. In landfill leachate tests, the highest leaching concentrations of PBDEs and TBBPA were determined at 30.39 and 12.27 μg/L. Meanwhile, the highest leaching rates were estimated to reach 0.08% and 1.00%, respectively, which were significantly influenced by the dissolved organic carbon contents of extracts, the hydrophobicities of target BFRs and the specific surface areas of WPCBs materials. These results proved that leaching from WPCBs was a significant emission source of BFRs in landfill and electronic waste recycling dumpsite

  16. Caustics of 1/rn binary gravitational lenses: from galactic haloes to exotic matter

    Science.gov (United States)

    Bozza, V.; Melchiorre, C.

    2016-03-01

    We investigate the caustic topologies for binary gravitational lenses made up of two objects whose gravitational potential declines as 1/rn. With n1 regime can be obtained with some violations of the energy conditions, one famous example being the Ellis wormhole. Gravitational lensing provides a natural arena to distinguish and identify such exotic objects in our Universe. We find that there are still three topologies for caustics as in the standard Schwarzschild binary lens, with the main novelty coming from the secondary caustics of the close topology, which become huge at higher n. After drawing caustics by numerical methods, we derive a large amount of analytical formulae in all limits that are useful to provide deeper insight in the mathematics of the problem. Our study is useful to better understand the phenomenology of galaxy lensing in clusters as well as the distinct signatures of exotic matter in complex systems.

  17. Identifying appropriate conditions for producing spindle-like causticizing precipitated calcium carbonate for paper filler applications

    Directory of Open Access Journals (Sweden)

    Jin Wang

    2012-11-01

    Full Text Available Causticizing precipitated calcium carbonate (CPCC as a by-product of the green liquor causticizing process can be used as paper filler to save resources and reduce costs. In this study, CPCC was prepared with green liquor and quicklime, which were obtained from an alkali recovery line of a paper mill. The factors influencing crystal morphology of CPCC, such as slaking temperature, slaking time, and causticizing time were investigated. The morphology of CPCC was observed and analyzed for optimizing reaction conditions. The following were compared: properties of CPCC obtained in this study, conventional CPCC (white mud from a paper mill, and commercial PCC as fillers. The results showed that slaking time and causticizing time were important for morphology control. Spindle-like and rod-like CPCC obtained in this study had better drainability and retention, higher paper bulk, opacity, and physical strength compared to conventional CPCC, and had nearly the same performances as commercial PCC.

  18. From Pop-Up Cards to Coffee-Cup Caustics: The Knight's Visor

    OpenAIRE

    Jakus, Stephanie; O'Rourke, Joseph

    2012-01-01

    As a pedagogical exercise, we derive the shape of a particularly elegant pop-up card design, and show that it connects to a classically studied plane curve that is (among other interpretations) a caustic of a circle.

  19. Industrial Experience on the Caustic Cracking of Stainless Steels and Nickel Alloys - A Review

    Energy Technology Data Exchange (ETDEWEB)

    Rebak, R B

    2005-10-09

    Caustic environments are present in several industries, from nuclear power generation to the fabrication of alkalis and alumina. The most common material of construction is carbon steel but its application is limited to a maximum temperature of approximately 80 C. The use of Nickel (Ni) alloys is recommended at higher temperatures. Commercially pure Ni is the most resistant material for caustic applications both from the general corrosion and the stress corrosion cracking (SCC) perspectives. Nickel rich alloys also offer a good performance. The most important alloying elements are Ni and chromium (Cr). Molybdenum (Mo) is not a beneficial alloying element and it dissolves preferentially from the alloy in presence of caustic environments. Austenitic stainless steels such as type 304 and 316 seem less resistant to caustic conditions than even plain carbon steel. Experimental evidence shows that the most likely mechanism for SCC is anodic dissolution.

  20. Study of matrix crack-tilted fiber bundle interaction using caustics and finite element method

    Science.gov (United States)

    Hao, Wenfeng; Zhu, Jianguo; Zhu, Qi; Yuan, Yanan

    2016-02-01

    In this work, the interaction between the matrix crack and a tilted fiber bundle was investigated via caustics and the finite element method (FEM). First, the caustic patterns at the crack tip with different distances from the tilted fiber were obtained and the stress intensity factors were extracted from the geometry of the caustic patterns. Subsequently, the shielding effect of the fiber bundle in front of the crack tip was analyzed. Furthermore, the interaction between the matrix crack and the broken fiber bundle was discussed. Finally, a finite element simulation was carried out using ABAQUS to verify the experimental results. The results demonstrate that the stress intensity factors extracted from caustic experiments are in excellent agreement with the data calculated by FEM.

  1. Computer simulation of the leaching and washing of waste in tanks C-106, AY-102, AZ-101, and AZ-102

    Energy Technology Data Exchange (ETDEWEB)

    MacLean, G.T.

    1997-05-01

    The waste in underground storage tanks C-106, AY-102, AZ-101, and AZ-102 will be used to prepare feed material for the proposed high level waste vitrification demonstration plant at Hanford. A chemical process simulation computer program called the Environment Simulation Program (ESP) was used to estimate the compositions and quantities of this waste and the products after pretreatment processing. The amount of precipitated material in Tank C-106 predicted to be dissolved by sluicing is 27 wt.%. The amount of precipitated material predicted to be dissolved by mild leaching is about 30% for the C-106 and AY-102 combined waste and about 50% for AZ-101, and 35% for AZ-102 wastes. The predicted caustic solution raw material requirements for leaching are 158 m{sup 3} for C-106 and AY-102, 60 m{sup 3} for AZ-101, and 146 m{sup 3} for AZ-102, all as 50 wt.% NAOH.

  2. Evaluation of glass leaching as nutrient source for microalgae growth

    International Nuclear Information System (INIS)

    Three glasses with an elemental composition similar to the nutrient ratio required for Spirulina platensis growth and with different SiO2 content have been prepared. The glasses were crushed and sieved into 2 different fractions and the effect of the particle size has been studied in terms of the leaching kinetics of each element. The chemical analysis of the leaching water was used for obtaining the dissolution rate curves for each element taking part of the glass composition. From the calculation of the leaching rate constant and the exponential constant of the lixiviation reaction, it has been evaluated the Spirulina platensis growth in ambient normal conditions of light, temperature and pH of the growing media. It has been concluded that, either from the modification of the chemical composition of the glass or its particle size, it is possible to tune the delivery of the nutrients to match the growth rate of Spirulina platensis. (Author)

  3. Scaling-Free Electrochemical Production of Caustic and Oxygen for Sulfide Control in Sewers.

    Science.gov (United States)

    Lin, Hui-Wen; Rabaey, Korneel; Keller, Jürg; Yuan, Zhiguo; Pikaar, Ilje

    2015-10-01

    Caustic shock-loading and oxygen injection are commonly used by the water industry for biofilm and sulfide control in sewers. Caustic can be produced onsite from wastewater using a two-compartment electrochemical cell. This avoids the need for import and storage of caustic soda, which typically represents a cost and a hazard. An issue limiting the practical implementation of this approach is the occurrence of membrane scaling due to the almost universal presence of Ca(2+) and Mg(2+) in wastewater. It results in a rapid increase in the cell voltage, thereby increasing the energy consumption of the system. Here, we propose and experimentally demonstrate an innovative solution for this problem involving the inclusion of a middle compartment between the anode and cathode compartments. Caustic was efficiently produced from wastewater over a period of 12 weeks and had an average Coulombic efficiency (CE) of 84.1 ± 1.1% at practically relevant caustic strengths (∼3 wt %). Neither membrane scaling nor an increase in the cell voltage was observed throughout the experiments. In addition, dissolved oxygen was produced in the anode, resulting in continuously oxygenated wastewater leaving the three-compartment cell. This membrane-scaling control strategy represents a major step forward toward practical implementation of on-site simultaneous electrochemical caustic and oxygen generation for sulfide control in sewers and also has the potential to be applied to other (bio)electrochemical systems receiving wastewater as source for product recovery. PMID:26377687

  4. Structured caustic vector vortex optical field: manipulating optical angular momentum flux and polarization rotation.

    Science.gov (United States)

    Chen, Rui-Pin; Chen, Zhaozhong; Chew, Khian-Hooi; Li, Pei-Gang; Yu, Zhongliang; Ding, Jianping; He, Sailing

    2015-05-29

    A caustic vector vortex optical field is experimentally generated and demonstrated by a caustic-based approach. The desired caustic with arbitrary acceleration trajectories, as well as the structured states of polarization (SoP) and vortex orders located in different positions in the field cross-section, is generated by imposing the corresponding spatial phase function in a vector vortex optical field. Our study reveals that different spin and orbital angular momentum flux distributions (including opposite directions) in different positions in the cross-section of a caustic vector vortex optical field can be dynamically managed during propagation by intentionally choosing the initial polarization and vortex topological charges, as a result of the modulation of the caustic phase. We find that the SoP in the field cross-section rotates during propagation due to the existence of the vortex. The unique structured feature of the caustic vector vortex optical field opens the possibility of multi-manipulation of optical angular momentum fluxes and SoP, leading to more complex manipulation of the optical field scenarios. Thus this approach further expands the functionality of an optical system.

  5. Preparation of manganese sulfate from low-grade manganese carbonate ores by sulfuric acid leaching

    Science.gov (United States)

    Lin, Qing-quan; Gu, Guo-hua; Wang, Hui; Zhu, Ren-feng; Liu, You-cai; Fu, Jian-gang

    2016-05-01

    In this study, a method for preparing pure manganese sulfate from low-grade ores with a granule mean size of 0.47 mm by direct acid leaching was developed. The effects of the types of leaching agents, sulfuric acid concentration, reaction temperature, and agitation rate on the leaching efficiency of manganese were investigated. We observed that sulfuric acid used as a leaching agent provides a similar leaching efficiency of manganese and superior selectivity against calcium compared to hydrochloric acid. The optimal leaching conditions in sulfuric acid media were determined; under the optimal conditions, the leaching efficiencies of Mn and Ca were 92.42% and 9.61%, respectively. Moreover, the kinetics of manganese leaching indicated that the leaching follows the diffusion-controlled model with an apparent activation energy of 12.28 kJ·mol-1. The purification conditions of the leaching solution were also discussed. The results show that manganese dioxide is a suitable oxidant of ferrous ions and sodium dimethyldithiocarbamate is an effective precipitant of heavy metals. Finally, through chemical analysis and X-ray diffraction analysis, the obtained product was determined to contain 98% of MnSO4·H2O.

  6. Characterization, Leaching, and Filtration Testing for Tributyl Phosphate (TBP, Group 7) Actual Waste Sample Composites

    Energy Technology Data Exchange (ETDEWEB)

    Edwards, Matthew K.; Billing, Justin M.; Blanchard, David L.; Buck, Edgar C.; Casella, Amanda J.; Casella, Andrew M.; Crum, J. V.; Daniel, Richard C.; Draper, Kathryn E.; Fiskum, Sandra K.; Jagoda, Lynette K.; Jenson, Evan D.; Kozelisky, Anne E.; MacFarlan, Paul J.; Peterson, Reid A.; Shimskey, Rick W.; Snow, Lanee A.; Swoboda, Robert G.

    2009-03-09

    .A testing program evaluating actual tank waste was developed in response to Task 4 from the M-12 External Flowsheet Review Team (EFRT) issue response plan. The bulk water-insoluble solid wastes that are anticipated to be delivered to the Waste Treatment and Immobilization Plant (WTP) were identified according to type such that the actual waste testing could be targeted to the relevant categories. Eight broad waste groupings were defined. Samples available from the 222S archive were identified and obtained for testing. The actual waste-testing program included homogenizing the samples by group, characterizing the solids and aqueous phases, and performing parametric leaching tests. The tributyl phosphate sludge (TBP, Group 7) is the subject of this report. The Group 7 waste was anticipated to be high in phosphorus as well as aluminum in the form of gibbsite. Both are believed to exist in sufficient quantities in the Group 7 waste to address leaching behavior. Thus, the focus of the Group 7 testing was on the removal of both P and Al. The waste-type definition, archived sample conditions, homogenization activities, characterization (physical, chemical, radioisotope, and crystal habit), and caustic leaching behavior as functions of time, temperature, and hydroxide concentration are discussed in this report. Testing was conducted according to TP-RPP-WTP-467.

  7. Behavior of SiO2 in the leaching process of alumina clinker with high concentration

    Institute of Scientific and Technical Information of China (English)

    Bin Chen; Xiaobin Li; Guihua Liu

    2008-01-01

    It is essential for alumina production by alkaline process to know the behavior of minerals containing Al and Si in basic solution, and the behavior of SiO2 in the process of clinker leaching is an important portion. To study the behavior of SiO2 in the process of high concentration clinker leaching, experiments were carried out in home-made reactors. The results indicate that factors,such as temperature, time, Al2O3 concentration, as well as SiO2 concentration, have profound impact on the SiO2 and Al2O3 concen-tration of pregnant liquor during the high concentration leaching. However, sodium carbonate and free caustic soda concentrations have no remarkable effect on it, thus they are the secondary factors compared with Al203 concentration. The concentration of SiO2 in the pregnant liquor could be reduced to a lower level when the major effect parameters of this process are controlled properly.

  8. Feasibility study for an additional HEPA filter leaching system in NWCF

    International Nuclear Information System (INIS)

    This report documents the feasibility of installing a second high-efficiency particulate air (HEPA) filter leaching system in the New Waste Calcining Facility at the Idaho Chemical Processing Plant (ICPP). A large spent filter backlog already exists at the ICPP, and it has been uncertain whether the existing HEPA filter leaching system will have a throughput rate sufficient to work off the existing backlog in a timely manner. Three areas within the New Waste Calcining Facility (NWCF) have been identified as possible locations for a second filter leaching system. This report examines the suitability of each location, identifies modifications that would be necessary-to install a filter leaching system at each location, examines the impact of modifying each location, and discusses recent efforts to estimate filter throughput using the existing filter leaching system. Based on all available information, installation of a second filter leaching system is not recommended at the present time

  9. Leaching studies of soda-lime-silica glass using deuterium- and 18O-enriched solutions

    International Nuclear Information System (INIS)

    With a glass of composition (in mol%) 74 SiO2,16 NaO, 10 CaO, various leaching experiments were conducted, in which besides solutions of normal isotopic composition deuterium- and 18O-enriched solutions were used. The concentration profiles of deuterium, hydrogen, and 18O in the sample were measured with nuclear analyzing techniques. A distinct H/D isotope effect was observed, showing that hydrogen takes part in the rate-determining step of leaching. The measured ratio of 18O uptake to hydrogen uptake during leaching gives evidence for exchange of oxygen between the glas network and water molecules contained in the leached layer. From measurements on the exchange of hydrogen and oxygen between solution and leached layer, a high mobility of water molecules in the leached layer and evidence for condensation of silanol groups was found. (orig.)

  10. The influence of mechanical activation of chalcopyrite on the selective leaching of copper by sulphuric acid

    Directory of Open Access Journals (Sweden)

    Achimovičová, M.

    2006-01-01

    Full Text Available In this paper chalcopyrite, CuFeS2, has been selective leached by H2SO4 as leaching agent (170 g/dm3 in procedure of hydrometallurgical production of copper. Mechanical activation of the chalcopyrite resulted in mechanochemical surface oxidation as well as in the mineral surface and bulk disordering. Furthermore, the formation of agglomerates during grinding was also occured. Surface changes of the samples using infrared spectroscopy and scanning electron microscopy methods were investigated before and after leaching. The leaching rate, specific surface area, structural disorder as well as copper extraction increased with the mechanical activation of mineral.

  11. Dephosphorization of Steelmaking Slag by Leaching with Acidic Aqueous Solution

    Science.gov (United States)

    Qiao, Yong; Diao, Jiang; Liu, Xuan; Li, Xiaosa; Zhang, Tao; Xie, Bing

    2016-09-01

    In the present paper, dephosphorization of steelmaking slag by leaching with acidic aqueous solution composed of citric acid, sodium hydroxide, hydrochloric acid and ion-exchanged water was investigated. The buffer solution of C6H8O7-NaOH-HCl system prevented changes in the pH values. Kinetic parameters including leaching temperature, slag particle size and pH values of the solution were optimized. The results showed that temperature has no obvious effect on the dissolution ratio of phosphorus. However, it has a significant effect on the dissolution ratio of iron. The dephosphorization rate increases with the decrease of slag particle size and the pH value of the solution. Over 90% of the phosphorus can be dissolved in the solution while the corresponding leaching ratio of iron was only 30% below the optimal condition. Leaching kinetics of dephosphorization follow the unreacted shrinking core model with a rate controlled step by the solid diffusion layer, the corresponding apparent activation energy being 1.233 kJ mol-1. A semiempirical kinetic equation was established. After leaching, most of the nC2S-C3P solid solution in the steelmaking slag was selectively dissolved in the aqueous solution and the iron content in the solid residue was correspondingly enriched.

  12. Experimental research on the improvement of gold recovery rate applying alkaline leaching pretreatment of a refractory arsenic and antimony contained gold concentrate%碱浸预处理提高某含砷锑难处理金精矿回收率的试验研究

    Institute of Scientific and Technical Information of China (English)

    李勇; 徐忠敏; 吕翠翠; 张治磊

    2013-01-01

    内蒙古某黄金矿山金精矿中,金主要包裹在黄铁矿及砷黄铁矿中,同时还有锑金属硫化物的存在.氰化浸出生产工艺中金的回收率比较低,只有76.63%.通过常规氰化工艺条件优化试验,金的回收率最高可达到80.15%.对该低品位含砷、锑难处理金精矿进行碱浸预处理,优先除砷、锑,以提高金氰化浸出率.确定了生产操作的最佳工艺条件,金的氰化回收率由原来的76.63%提高到92%,试验获得了较好技术指标和经济效益.%Gold in the gold concentrates of a mine in Inner Mongolia is mainly wrapped in pyrite and arsenopy-rite, and together with the existence of metallic antimony sulfide, cyanide leaching rate of gold in the production is relatively low,only 76. 63 %. By optimization experiment of conventional cyanide process conditions, gold recovery rate can reach a max of 80. 15 % , using alkaline leaching to pretreat the arsenic and antimony contained refractory gold concentrate, with the arsenic and antimony first removed, the cyanide leaching rate of gold increased from 76. 63 % to 92 % , achieving satisfactory technical and economical index.

  13. Life cycle assessment and residue leaching: The importance of parameter, scenario and leaching data selection

    DEFF Research Database (Denmark)

    Allegrini, Elisa; Butera, Stefania; Kosson, D.S.;

    2015-01-01

    , due to the potential leaching of toxic substances. In waste LCA studies where residue utilisation is included, leaching has generally been neglected. In this study, municipal solid waste incineration bottom ash (MSWI BA) was used as a case study into three LCA scenarios having different system......Residues from industrial processes and waste management systems (WMSs) have been increasingly reutilised, leading to landfilling rate reductions and the optimisation of mineral resource utilisation in society. Life cycle assessment (LCA) is a holistic methodology allowing for the analysis...... of systems and products and can be applied to waste management systems to identify environmental benefits and critical aspects thereof. From an LCA perspective, residue utilisation provides benefits such as avoiding the production and depletion of primary materials, but it can lead to environmental burdens...

  14. H-Area Acid/Caustic Basin Groundwater Monitoring Report

    International Nuclear Information System (INIS)

    The four monitoring wells at the H-Area Acid/Caustic Basin are sampled quarterly as part of the Savannah River Site (SRS) Groundwater Monitoring Program and to comply with a consent decree signed May 26, 1988, by the US District Court (District of South Carolina, Aiken Division). During fourth quarter 1993, samples from the monitoring wells received comprehensive analyses. Monitoring results that exceeded the final Primary Drinking Water Standards (PDWS), the SRS flagging criteria, or the SRS turbidity standard are the focus of this report. During fourth quarter 1993, tritium exceeded the final PDWS in all four HAC wells, with activities between 3.8E + 01 and 4.6E + 01 pCi/mL. Aluminum exceeded its Flag 2 criterion in wells HAC 2, 3, and 4. Iron exceeded its Flag 2 criterion in wells HAC 1, 2, and 3. Specific conductance was elevated in well HAC 2, total organic halogens exceeded its Flag 2 criterion in wells HAC 2 and 3, and manganese was elevated in wells HAC 3 and 4. No well samples exceeded the SRS turbidity standard

  15. Our experience with caustic oesophageal burn in South of Iran

    Directory of Open Access Journals (Sweden)

    Seyed M. V. Hosseini

    2011-01-01

    Full Text Available Context: The alkaline oesophageal burn (EB is a very debilitating injury and common in the southern rural area of Iran, where the air conditioning systems are cleaned with an alkaline liquid, which is accidentally ingested by children. Aims: The aim is to share our experiences with caustic injury in children. Settings and Design : A ′before′ and ′after′ clinical trial. Materials and Methods: From November 2006-2009, 35 cases of alkaline burns were referred to our center. All underwent flexible endoscopy and thereafter received steroid, antibiotic and H2 blocker. They subsequently underwent rigid oesophagoscopy, with grade IIb or higher burns, for inserting the two different kinds of stents. Results: Four out of 10 (GIIa < underwent dilatation occasionally. Fifteen (GIIb with early large stent (eight weeks developed complications (three antral contractures, one oesophagotracheal fistula, one tracheobronchial fistula, three perforations, three deaths, and the remaining cases had not undergone dilatation yet. Four out of 10 with (GIIb, who had small stents (Six months and early gastrostomy needed dilatation every four to six weeks and all recovered, with no significant complications. Conclusions: Early use of gastrostomy prevents malnutrition in patients. Small size stents are much more tolerable for a prolonged time are not obstructed by saliva that washes the wall of the damaged oesophagus continuously and promotes healing.

  16. Behavior of leaching and precipitation of weathering crust ion-absorbed type by magnetic field

    Institute of Scientific and Technical Information of China (English)

    QIU Tingsheng; FANG Xihui; CUI Lifeng; FANG Yanxi

    2008-01-01

    With weathering crust Ion-Absorbed Type Rare Earth (IATRE) ores in southern Jiangxi as an example, rare earth percolation leaching and leaching solution precipitation process research were carried out under conditions of magnetic field. The effect on the rare earth leaching process such as magnetic field strength, magnetization time, magnetization manner, and other factors were discussed. The effect on the mother rare earth liquor sedimentation rate, purity, and crystallization behavior such as magnetic field strength, magnetization time, and magnetization manner were investigated. Leaching and precipitation mechanism of magnetization on IATRE were analyzed. The results showed that the magnetic treatment can improve leaching rate of weathering crust IATRE and the sedimentation rate, and reduce consumption of reagents.

  17. The effects of types of media on uranium leaching using metabolite of Aspergillus niger

    International Nuclear Information System (INIS)

    To investigate the influences of different media to uranium leaching applying with metabolite of Aspergillus niger, PSA and glucose-steepwater medium were used for the culture of Aspergillus niger, and the metabolite of Aspergillus niger with different pH value produced in the diverse culture temperature were obtained which was applied on the tests of uranium leaching as leaching agent. The test results show that the maximum leaching rate is 83.05% when the leaching agent is the metabolite of Aspergillus niger produced by PSA, as for the glucose- steepwater medium, the maximum leaching rate is 68.20%. The pH value of the metabolite of Aspergillus niger of the two kinds of media has a significant effect on the leaching rate. When PSA is adopted, the best leaching rate appears at the pH value of metabolite ranging from 2.0 to 2.5, and as for the glucose-steepwater medium, the pH value is below 2.1. (authors)

  18. Single-pass continuous-flow leach test of PNL 76-68 glass: some selected Bead Leach I results

    International Nuclear Information System (INIS)

    A single-pass continuous-flow leach test of PNL 76-68 glass beads (7 mm dia) was concluded after 420 days of uninterrupted operation. Variables included in the experimental matrix were flow-rate, leachant composition, and temperature. Analysis was conducted on all leachate samples for 237Np and 239Pu as well as a number of nonradioactive elements. Results indicated that flow-rate and leachant systematically affected the leach rate, but only slightly. Temperature effects were significant. Plutonium leach rate was lower at higher temperature suggesting that Pu sorption onto the beads was enhanced at the higher temperature. The range of leach rates for all analyzed elements (except Pu), at both temperatures, at all three flow rates, and with all three leachant compositions varied over only three orders of magnitude. The range of variables used in this experiment covered those expected in many proposed repository environments. The preliminary interpretation of the results aPPh3 also reacted with Mn2(CO)10 and Cp2Mo2(CO)6 to give a variety of products at room temperature. A radical mechanism was suggested

  19. A preferential flow leaching index

    NARCIS (Netherlands)

    McGrath, G.S.; Hinz, C.; Sivapalan, M.

    2009-01-01

    The experimental evidence suggests that for many chemicals surface runoff and rapid preferential flow through the shallow unsaturated zone are significant pathways for transport to streams and groundwater. The signature of this is the episodic and pulsed leaching of these chemicals. The driver for t

  20. Leach and EP [extraction procedure] toxicity tests on grouted waste from Tank 106-AN

    International Nuclear Information System (INIS)

    Pacific Northwest Laboratory is conducting laboratory experiments to produce leach rate data for various waste species that will be contained in grout at Hanford. In the work reported here, grout made from Tank 106-AN liquid waste was used to produce empirical leach rate data for several radionuclides (60Co, 90Sr, 99Tc, 129I, 137Cs, and 241Am), stable major components (NO3-, NO2-, F, Cl, and Na), and trace metals (Cr, Mo, and Ni). Two types of tests were used to produce leach rate data: an intermittent replacement leach test (ANS 16.1 leach test) and a static leach test. Measured effective diffusivities of key species are as follows: 4 to 6 x 10-8 cm2/sec for 99Tc, 3 to 7 x 10-8 cm2/sec for 129I, 4 to 6 x 10-9 cm2/sec for nitrate, and 6 to 7 x 10-9 cm2/sec for nitrite. The leach indices of all species studied are above (more favorable than) the waste form criteria. The leach indices for 99Tc and 129I are 7.4 ± 1.2 and 7.6 ± 0.4, respectively, and are being further investigated in continuing studies of double-shell slurry feed grouts. An Extraction Procedure (EP) toxicity test was also conducted and the grouted water is considered nontoxic per this test protocol. 19 refs., 9 figs., 8 tabs

  1. An active dealkalization of red mud with roasting and water leaching.

    Science.gov (United States)

    Zhu, Xiaobo; Li, Wang; Guan, Xuemao

    2015-04-01

    The research has focused on the dealkalization of red mud after active roasting and water leaching, which is obtained from bauxite during alumina production. The main factors such as roasting temperature, roasting time, water leaching stage, leaching temperature, leaching reaction time and liquid to solid ratio were investigated. The mechanism of dealkalization was in-depth studied by using ICP-AES, XRD, TG-DSC, SEM-EDS and leaching kinetic. The results show that the dealkalization rate reached 82% under the condition of roasting temperature of 700 °C, roasting time of 30 min, four stage water leaching, liquid to solid ratio of 7 mL/g, leaching temperature of 90 °C and reaction time of 60 min. The diffraction peak of Na6CaAl6Si6(CO3)O24 · 2H2O in red mud was decreased during the active roasting process, whereas the mineral phases of NaOH · H2O and Na2Ca(CO3)2 were appeared. The content of alkali obviously decreased and the grade of other elements increased during the process of active roasting and water leaching, which was in favor of next application process of red mud. The water leaching was controlled by internal diffusion of SCM and the apparent activation energy was 22.63 kJ/mol. PMID:25559862

  2. Code Combining Based Cooperative LEACH Protocol for Wireless Sensor Networks

    Science.gov (United States)

    Asaduzzaman; Kong, Hyung-Yun

    This letter proposes a simple modification of LEACH protocol to exploit its multi-hop scenario for user cooperation. Instead of a single cluster-head we propose M cluster-heads in each cluster to obtain the diversity of order M. All cluster-heads gather data from all sensor nodes within the cluster using the same technique as LEACH. Cluster-heads transmit gathered data cooperatively towards the destination or higher order cluster-head. We propose a code combining based cooperative protocol. We also develop the upper bounds on frame error rate (FER) for our proposal. Simulation and analysis show that our proposal can significantly prolong the system lifetime.

  3. Testing the Dark Matter Caustic Theory Against Observations in the Milky Way

    CERN Document Server

    Dumas, Julie; Niedzielski, Bethany; Susser, Adam; Thompson, Jeffery M; Weiss, Jake; Lewis, Kim M

    2015-01-01

    We test a particular theory of dark matter in which dark matter axions form ring "caustics" in the plane of the Milky Way against actual observations of Milky Way stars. According to this theory, cold, collisionless dark matter particles with angular momentum flow in and out of the Milky Way on sheets. These flows form caustic rings (at the positions of the rings, the density of the flow is formally infinite) at the locations of closest approach to the Galactic center. We show that the caustic ring dark matter theory reproduces a roughly logarithmic halo, with large perturbations near the rings. We show that the theory can reasonably match the observed rotation curve of the Milky Way. We explore the effects of the caustic rings on dwarf galaxy tidal disruption using N-body simulations. In particular, simulations of the Sagittarius dwarf galaxy tidal disruption in a caustic ring halo potential match observations of the trailing tidal tail as far as 90 kpc from the Galactic center; they do not, however, match t...

  4. Caustic Ingestion in Children: a Systematic Review and Meta-Analysis

    Science.gov (United States)

    Rafeey, Mandana; Ghojazadeh, Morteza; Sheikhi, Saeede; Vahedi, Leila

    2016-01-01

    Introduction:Caustic ingestion that occurs accidently is one of the most common problems in children. Methods: This systematic review has been performed by searching the databases including Science Direct, ProQuest, Google Scholar, and PubMed. A strategic search was performed with keywords including caustic, corrosive, ingestion, and children, and was limited to articles in English and Persian. Data were analyzed using Comprehensive Meta-Analysis2 and PASW Statistics 18. Results: We selected 64 articles regarding caustic ingestion with a total sample of 11,345 cases. The data analysis indicated a higher consumption in young boys (age range 2.78 (2.02) years (OR=0.53 with a 95% confidence interval of 0.49-0.57 (P=0.08)). The most common caustic substances were household cleaning agents, particularly bleaches and cleaners. Esophageal cancer and death were reported as well as digestive and respiratory complications. Invasive and expensive techniques are frequently used for diagnosis, treatment and follow up. Conclusion: The results demonstrated that although caustic ingestion is a serious problem among children, it is a preventable and manageable issue. Therefore, appropriate efforts by families, government, factories, health team and media should be made to handle adequately this matter.

  5. 碱性加压浸出三次氨浸渣中钼的实验研究%Experimental Study on Alkaline Pressure Leaching of Molybdenum from Ammonia Leach Residues

    Institute of Scientific and Technical Information of China (English)

    沈裕军; 杨文魁; 公彦兵; 丁喻

    2011-01-01

    采用加压碱浸的方法浸出钼焙砂三次氨浸渣中的钼,研究了浸出剂、温度、时间、催化剂等对钼浸出率的影响,得出钼浸出最优条件为:Na2CO3加入量为30%,液固比为3,催化剂A加入量为6%,温度为180℃,浸出时间为1h,此条件下钼浸出率可达98%;进行了4次连续循环浸出试验,钼浸出率均在98%以上.%Pressure alkaline leaching was introduced to extract molybdenum from ammonia leaching residues after molybdenum was treated by ammonia leaching process for three times. The effects of leaching agent, temperature, time and catalyst on the leaching rate of molybdenum were investigated. The best leaching conditions of molybdenum were as follows; the addition amount of Na2CO, was 30% , liquid-solid ratio was 3, the addition amount of catalyst A was 6% , the temperature was 180 ℃ and leaching time was 1 h. Under these conditions the leaching rate of molybdenum reached 98% , and the leaching rate of molybdenum from four cycling leaching experiments were all above 98%.

  6. Effect of Antifoam Agent on Oxidative Leaching of Hanford Tank Sludge Simulants

    Energy Technology Data Exchange (ETDEWEB)

    Rapko, Brian M.; Jones, Susan A.; Lumetta, Gregg J.; Peterson, Reid A.

    2010-02-26

    Oxidative leaching of simulant tank waste containing an antifoam agent (AFA) to reduce the chromium content of the sludge was tested using permanganate as the oxidant in 0.25 M NaOH solutions. AFA is added to the waste treatment process to prevent foaming. The AFA, Dow Corning Q2-3183A, is a surface-active polymer that consists of polypropylene glycol, polydimethylsiloxane, octylphenoxy polyethoxy ethanol, treated silica, and polyether polyol. Some of the Hanford Tank Waste Treatment and Immobilization Plant (WTP) waste slurries contain high concentrations of undissolved solids that would exhibit undesirable behavior without AFA addition. These tests were conducted to determine the effect of the AFA on oxidative leaching of Cr(III) in waste by permanganate. It has not previously been determined what effect AFA has on the permanganate reaction. This study was conducted to determine the effect AFA has on the oxidation of the chromium, plus plutonium and other criticality-related elements, specifically Fe, Ni and Mn. During the oxidative leaching process, Mn is added as liquid permanganate solution and is converted to an insoluble solid that precipitates as MnO2 and becomes part of the solid waste. Caustic leaching was performed followed by an oxidative leach at either 25°C or 45°C. Samples of the leachate and solids were collected at each step of the process. Initially, Battelle-Pacific Northwest Division (PNWD) was contracted by Bechtel National, Inc. to perform these further scoping studies on oxidative alkaline leaching. The data obtained from the testing will be used by the WTP operations to develop procedures for permanganate dosing of Hanford tank sludge solids during oxidative leaching. Work was initially conducted under contract number 24590-101-TSA-W000-00004. In February 2007, the contract mechanism was switched to Pacific Northwest National Laboratory (PNNL) operating Contract DE-AC05-76RL01830. In summary, this report describes work focused on

  7. Time Motion Study for Modular Caustic Solvent Extraction Unit

    International Nuclear Information System (INIS)

    The Defense Waste Processing Facilities (DWPF) at the Savannah River Site (SRS) is used to process high-level radioactive waste from the Tank Farm into borosilicate glass to reduce the mobility of the radionuclides and has processed and vitrified nuclear wastes into canisters for long-term disposal since FY96. All wastes vitrified to date in DWPF are ''sludge only'' wastes. The old salt waste processing technology, ITP, was suspended in FY98 due to benzene build-up inside the tank. The new selected technologies for treating the salt waste are Actinide Removal Process (ARP) and Caustic Side Solvent Extraction process (CSSX). The Modular CSSX Unit (MCU) is a cesium removal process that will be operated downstream of the ARP. The MCU is a short-term method for cesium removal, which uses the same technology as the Salt Waste Processing Facility (SWPF). Once the SWPF becomes operational, the MCU will be shut down. The modeling request is from the MCU project to verify the validity of its Concept Design Package. The modeling task is not typical because there are five different facilities/projects/processes involved, i.e., Tank Farm, ARP, MCU, Saltstone, and DWPF. Each facility, project, and process has their own management team and organization, with its own fiscal responsibility and performance accountability. In addition, from a task cost perspective, MCU desires to minimize modeling not directly associated with their facility. The balancing of comprehensive analysis with limited granularity is challenging. The customer expectation is the model should be small and delivered within weeks. Modeling a stand-alone MCU will not yield overall meaningful results because it can be expected that most problems will occur at interfaces with other facilities. This paper discusses how we set out our modeling strategy, overcame obstacles, avoided touchy issues, and delivered the modeling result on time and on budget

  8. PAHs leaching test for solidified waste

    Energy Technology Data Exchange (ETDEWEB)

    Henzler, R.; Grathwohl, P. [Tuebingen Univ. (Germany). Center for Applied Geoscience

    2003-07-01

    The treatment of waste materials to allow recycling or safe disposal is a rapidly expanding business, but also subject to increasing public awareness of enviromental issues and tightening of the regularise governing in many countries. One of the most widely used treatment for wastes is stabilisation /solidification using a cement matrix to obtain a monolithic residue. The most common test procedure to assess the risks of contaminant release into water (seepage, surface and groundwater) is the so-called ''tank leaching test'' or ''diffusion test'' (NEN 7345, Mulder et al 2001, Hohberg et al 2000), in which a solidified specimen is leached with water during different periods of time. The tests are usually done at room temperatures between 20 C and 25 C. However, the temperature under natural conditions are lower resulting in lower contaminant release rates. (subsurface temperature: 5 C - 10 C). If the thermodynamics of the contaminant release, especially the activation energy of desorption and diffusion, is known, it is possible to estimate the contaminant release for lower temperatures, e.g. down to groundwater temperatures. In addition the test can be accelerated if performed at high temperatures.

  9. New strategies for treatment and reuse of spent sulfidic caustic stream from petroleum industry

    Directory of Open Access Journals (Sweden)

    Jéssica Frontino Paulino

    2012-01-01

    Full Text Available This work examines traditional and new routes for removal of H2S and other sulfur compounds from spent sufidic caustic (SSC. SH- (hydrogenosulfide and S2- (sulfide ions were quantitatively oxidized at 25 ºC using H2O2, NaOCl or a spent sulfochromic mixture. SH-/S2- ions were also removed via reaction with freshly prepared iron or manganese hydroxides, or after passing the SSC through strong basic anion exchange resins (OH- form. The treated caustic solution, as well as iron/manganese hydroxides, removed H2S from diesel samples at 25 ºC. SSC treatment via strong basic anion-exchange resins produced the treated caustic solution with the highest free alkalinity.

  10. INTER-CONTACT FORCE ANALYSIS OF IMPACTED DISK ASSEMBLY BY DYNAMIC CAUSTICS

    Institute of Scientific and Technical Information of China (English)

    LI Ming(李明); ZHANG Jue; FANG Jing(方竞)

    2003-01-01

    The caustic method was utilized to study the contact force transmission in disk assemblies under impact load. The mapping equations were obtained based on the first invariant of the stress components in the disk subject to a normal concentrated force, and a characteristic dimension of the maximum size in the caustic curve was proposed to evaluate the contact force between the disks.Transient patterns of the caustic shadows were recorded by means of a high-speed camera of off-focus imaging, then the histories of the inter-contact forces among the disks were obtained with respect to the conditions of different masses and heights of the falling hammers. The influence of the impact loading and impulsive velocity was analyzed with respect to the force responses of the disk assembly,the double-peak phenomenon with comparison to the initial masses, and the energy dissipation of the systems under impact of different momentums.

  11. Phosphorus leaching in an acid tropical soil "recapitalized" with phosphate rock and triple superphosphate.

    Science.gov (United States)

    Gikonyo, Esther W; Zaharah, Abdul R; Hanafi, Mohamed M; Anuar, Rahim A

    2010-01-01

    With high rates of phosphorus applied to increase "capital P" as a stock for plant uptake over several years, the question of P leaching is inevitable. We conducted an intact soil column experiment in the field to evaluate P leached from soils treated with triple superphosphate (TSP) and Gafsa phosphate rock (GPR) at 300, 600, and 900 kg P ha-1 with and without integration of cattle manure. The lysimeters, made from PVC tubes of 30-cm length, were inserted into the soil up to the 25-cm depth. The tubes were fitted with a resin bag containing a mixture of cation and anion exchange resin (50:50) at the lower end of the tube inserted into the soil. The tubes, arranged in a completely randomized design, were sampled randomly at 10-week intervals for 12 months. Phosphorus extractable from the top- and subsoil at the end of experiment and leached P were determined. More P was leached out from TSP (threefold) compared to GPR, and the amount of P leached increased with increasing rates of P fertilizer applied. Application of manure intensified the amounts of P leached from TSP, particularly at the 6-month sampling time. There was hardly any substantial P leached from the soil treated with GPR. Thus, for effective and efficient long-term P fertilizer management strategies, choosing the right P fertilizer source and monitoring P losses through leaching has to be done for enhanced fertilizer use efficiency and thus reducing P pollution of ground waters. PMID:20694445

  12. Investigation of Leaching Kinetics of Copper from Malachite Ore in Ammonium Nitrate Solutions

    Science.gov (United States)

    Ekmekyapar, Ahmet; Aktaş, Evrim; Künkül, Asim; Demirkiran, Nizamettin

    2012-08-01

    The production of metallic copper from low-grade copper ores is generally carried out by hydrometallurgical methods. Leaching is the first prerequisite of any hydrometallurgical process. Solutions containing ammonia may allow for selective leaching of the copper from the ore. In this study, the leaching kinetics of malachite, which is an oxidized copper ore, in ammonium nitrate solutions was examined. The effects of some experimental parameters on the leaching process were investigated, and a kinetic model to represent the effects of these parameters on the leaching rate was developed. It was determined that the leaching rate increased with increasing solution concentration, temperature, and agitation speed, as well as decreasing particle size. It was found that the leaching reaction followed the mixed kinetic controlled model, which includes two different leaching processes including the surface chemical reaction (303 K to 323 K [30 °C to 50 °C]) and diffusion through a porous product layer (323 K to 343 K [50 °C to 70 °C]). The activation energies of these sequential steps were determined to be 95.10 and 29.50 kJ/mol, respectively.

  13. Diffraction and Dissipation of Atmospheric Waves in the Vicinity of Caustics

    Science.gov (United States)

    Godin, O. A.

    2015-12-01

    A large and increasing number of ground-based and satellite-borne instruments has been demonstrated to reliably reveal ionospheric manifestations of natural hazards such as large earthquakes, strong tsunamis, and powerful tornadoes. To transition from detection of ionospheric manifestations of natural hazards to characterization of the hazards for the purposes of improving early warning systems and contributing to disaster recovery, it is necessary to relate quantitatively characteristics of the observed ionospheric disturbances and the underlying natural hazard and, in particular, accurately model propagation of atmospheric waves from the ground or ocean surface to the ionosphere. The ray theory has been used extensively to model propagation of atmospheric waves and proved to be very efficient in elucidating the effects of atmospheric variability on ionospheric signatures of natural hazards. However, the ray theory predicts unphysical, divergent values of the wave amplitude and needs to be modified in the vicinity of caustics. This paper presents an asymptotic theory that describes diffraction, focusing and increased dissipation of acoustic-gravity waves in the vicinity of caustics and turning points. Air temperature, viscosity, thermal conductivity, and wind velocity are assumed to vary gradually with height and horizontal coordinates, and slowness of these variations determines the large parameter of the problem. Uniform asymptotics of the wave field are expressed in terms of Airy functions and their derivatives. The geometrical, or Berry, phase, which arises in the consistent WKB approximation for acoustic-gravity waves, plays an important role in the caustic asymptotics. In addition to the wave field in the vicinity of the caustic, these asymptotics describe wave reflection from the caustic and the evanescent wave field beyond the caustic. The evanescent wave field is found to play an important role in ionospheric manifestations of tsunamis.

  14. Use of low-cost heat sources to improve the efficiency of heap leaching of uranium ores. Part of a coordinated programme on bacterial leaching of uranium ores

    International Nuclear Information System (INIS)

    Basic technical parameters are given of two solar heaters designed for use in heap leaching of uranium ores. Inexpensive and easily available materials such as flat glass panes, glass tubing and corrugated metal sheets were used in the construction of the heaters. Under optimum conditions, the heaters can produce temperature differentials of 520C (500C) at the flow rate of 30ml/min. The dependence of percent recovery on the temperature of solutions in heap leaching of ore from 'El Nopal' was studied. Even though no precise correlation was found, an increase in the temperature of solutions seems to improve the efficiency of heap leaching

  15. Leaching kinetics of ionic rare-earth in ammonia-nitrogen wastewater system added with impurity inhibitors

    Institute of Scientific and Technical Information of China (English)

    邱廷省; 朱冬梅; 方夕辉; 曾清华; 高广阔; 朱华磊

    2014-01-01

    Ammonia-nitrogen wastewater is produced during the dressing and smelting process of rare-earth ores. Such wastewater includes a very high concentration of NH4+, as well as other ions (e.g., NH4+, RE3+, Al3+, Fe3+, Ca2+, Cl–, and SiO32–) with a pH of 5.4–5.6. Its direct discharge will pollute, yet it can be recycled and used as a leaching reagent for ionic rare-earth ores. In this study, leaching kinetics studies of both rare earth ions and impurity ion Al3+were conducted in the ammonia-nitrogen wastewater system with the aid of impurity inhibitors. Results showed that the leaching process of rare-earth followed the internal diffusion kinetic model. When the temperature was 298 K and the concentration of NH4+was 0.3 mol/L, the leaching reaction rate constant of ionic rare-earth was 1.72 and the apparent activation energy was 9.619 kJ/mol. The leaching rate was higher than that of conventional leaching system with ammonium sulfate, which indicated that ammonia-nitrogen wastewater system and the addition of impurity inhibitors could pro-mote ionic rare-earth leaching. The leaching kinetic process of impurity Al3+did not follow either internal diffusion kinetic model or chemical reaction control, but the hybrid control model which was affected by a number of process factors. Thus, during the industrial production the leaching of impurity ions could be reduced by increasing the concentration of impurity inhibitors, reducing the leach-ing temperature to a proper range, accelerating the seepage velocity of leaching solution, or increasing the leaching rate of rare earths.

  16. Biological treatment of sulfidic spent caustics under haloalkaline conditions using soda lake bacteria

    OpenAIRE

    Graaff, de, R.J.

    2012-01-01

    In this thesis, the development of a newbiotechnological process for the treatment of undiluted sulfidic spent caustics (SSC’s) using soda lake bacteria is described. SSC’s are waste solutions that are formed in the oil and gas industry due to the caustic (NaOH) scrubbing of hydrocarbon streams for the removal of sulfur compounds.Without treatment, SSC’s may impose serious environmental problems because of their alkalinity (pH>12), salinity (Na+ 5-12 wt%) and high sulfide...

  17. Leaching of wood ash - Laboratory and field studies; Lakning av vedaska - Laboratorie- och faeltstudier

    Energy Technology Data Exchange (ETDEWEB)

    Larsson, Per-Erik

    2012-02-15

    High forest production leads to diminishing amounts of base cations and micro nutrients in forest soils. This is due to uptake in, and harvest of, the trees. Losses can be compensated for by spreading stabilized wood ash on the forest ground, which means recycling of base cations and micro nutrients. Chemical composition of wood ash can easily be described by standard methods in the laboratory. However, this does not include the process of leaching in nature, such as which components and leaching rate for different compounds. During field conditions several factors are added, which are not available in the laboratory. After almost 10 years in the forest soils there still remains large quantities of the original product. Only 10-30 % of the wood ash products and 5 % of the lime product has been leached. In the laboratory study the leached amount was slightly larger, at the most 35 % for wood ash and 20 % for lime. Both studies indicate long time for weathering of the products in forest soils. Slower leaching rate from pellets of wood ash compared to leaching rate from crushed wood ash in the laboratory study is not verified by the field study. This indicates limited possibilities to control rates of leaching in the environment

  18. Saltstone Oxidation Study: Leaching Method

    Energy Technology Data Exchange (ETDEWEB)

    Langton, C. A.; Stefanko, D. B.; Burns, H. H.

    2013-02-24

    Cementitious waste forms can be designed to chemically stabilize selected contaminants, such as Tc{sup +7} and Cr{sup +6}, by chemically reduction to lower valance states, Tc{sup +4} and Cr{sup +3}, respectively, and precipitation of these species in alkaline media as low solubility solid phases. Data for oxidation of this type of cementitious waste form cured under field conditions as a function of time is required for predicting the performance of the waste form and disposal facility. The rate of oxidation (oxidation front advancement) is an important parameter for predicting performance because the solubilities of some radionuclide contaminants, e.g., technetium, are a function of the oxidation state. A non-radioactive experiment was designed for quantifying the oxidation front advancement using chromium, as an approximate redox-sensitive surrogate (Cr{sup +6} / Cr{sup +3}) for technetium (Tc{sup +7} / Tc{sup +4}). Nonradioactive cementitious waste forms were prepared in the laboratory and cured under both laboratory and ?field conditions.? Laboratory conditions were ambient temperature and sealed sample containers. Field conditions were approximated by curing samples in open containers which were placed inside a plastic container stored outdoors at SRS. The container had a lid and was instrumented with temperature and humidity probes. Subsamples as thin as 0.2 mm were taken as a function of distance from the exposed surface of the as-cast sample. The subsamples were leached and the leachates were analyzed for chromium, nitrate, nitrite and sodium. Nitrate, nitrite, and sodium concentrations were used to provide baseline data because these species are not chemically retained in the waste form matrix to any significant extent and are not redox sensitive. ?Effective? oxidation fronts for Cr were measured for samples containing 1000, 500 and 20 mg/kg Cr added as soluble sodium chromate, Na{sub 2}CrO{sub 4}. For a sample cured for 129 days under field conditions

  19. [Mixture Leaching Remediation Technology of Arsenic Contaminated Soil].

    Science.gov (United States)

    Chen, Xun-feng; Li, Xiao-ming; Chen, Can; Yang, Qi; Deng, Lin-jing; Xie, Wei-qiang; Zhong, Yui; Huang, Bin; Yang, Wei-qiang; Zhang, Zhi-bei

    2016-03-15

    Soil contamination of arsenic pollution has become a severely environmental issue, while soil leaching is an efficient method for remediation of arsenic-contaminated soil. In this study, batch tests were primarily conducted to select optimal mixture leaching combination. Firstly, five conventional reagents were selected and combined with each other. Secondly, the fractions were analyzed before and after the tests. Finally, to explore the feasibility of mixed leaching, three soils with different arsenic pollution levels were used to compare the leaching effect. Comparing with one-step washing, the two-step sequential washing with different reagents increased the arsenic removal efficiency. These results showed that the mixture of 4 h 0.5 mol · L⁻¹ NaOH + 4 h 0.1 mol · L⁻¹ EDTA was found to be practicable, which could enhance the removal rate of arsenic from 66.67% to 91.83%, and the concentration of arsenic in soil was decreased from 186 mg · kg⁻¹ to 15.2 mg · kg⁻¹. Furthermore, the results indicated that the distribution of fractions of arsenic in soil changed apparently after mixture leaching. Leaching process could significantly reduce the available contents of arsenic in soil. Moreover, the mixture of 0.5 mol · L⁻¹ NaOH + 0.1 mol L⁻¹ EDTA could well decrease the arsenic concentration in aluminum-type soils, while the mixture of 0.5 mol · L⁻¹ OX + 0.5 mol · L⁻¹ NaOH could well decrease the arsenic concentration in iron-type soils.

  20. An active dealkalization of red mud with roasting and water leaching

    International Nuclear Information System (INIS)

    Highlights: • The dealkalization of active roasting and water leaching from red mud was put forward. • The main factors on dealkalization during active roasting and water leaching were investigated. • The mechanism of dealkalization from red mud was in-depth studied in the process. - Abstract: The research has focused on the dealkalization of red mud after active roasting and water leaching, which is obtained from bauxite during alumina production. The main factors such as roasting temperature, roasting time, water leaching stage, leaching temperature, leaching reaction time and liquid to solid ratio were investigated. The mechanism of dealkalization was in-depth studied by using ICP–AES, XRD, TG-DSC, SEM–EDS and leaching kinetic. The results show that the dealkalization rate reached 82% under the condition of roasting temperature of 700 °C, roasting time of 30 min, four stage water leaching, liquid to solid ratio of 7 mL/g, leaching temperature of 90 °C and reaction time of 60 min. The diffraction peak of Na6CaAl6Si6(CO3)O24·2H2O in red mud was decreased during the active roasting process, whereas the mineral phases of NaOH·H2O and Na2Ca(CO3)2 were appeared. The content of alkali obviously decreased and the grade of other elements increased during the process of active roasting and water leaching, which was in favor of next application process of red mud. The water leaching was controlled by internal diffusion of SCM and the apparent activation energy was 22.63 kJ/mol

  1. An active dealkalization of red mud with roasting and water leaching

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, Xiaobo, E-mail: zhuxiaobo0119@126.com [School of Materials Science and Engineering, Henan Polytechnic University, Jiaozuo, Henan 454000 (China); Henan Key Discipline Open Laboratory of Mining Engineering Materials, Henan 454000 (China); Li, Wang; Guan, Xuemao [School of Materials Science and Engineering, Henan Polytechnic University, Jiaozuo, Henan 454000 (China); Henan Key Discipline Open Laboratory of Mining Engineering Materials, Henan 454000 (China)

    2015-04-09

    Highlights: • The dealkalization of active roasting and water leaching from red mud was put forward. • The main factors on dealkalization during active roasting and water leaching were investigated. • The mechanism of dealkalization from red mud was in-depth studied in the process. - Abstract: The research has focused on the dealkalization of red mud after active roasting and water leaching, which is obtained from bauxite during alumina production. The main factors such as roasting temperature, roasting time, water leaching stage, leaching temperature, leaching reaction time and liquid to solid ratio were investigated. The mechanism of dealkalization was in-depth studied by using ICP–AES, XRD, TG-DSC, SEM–EDS and leaching kinetic. The results show that the dealkalization rate reached 82% under the condition of roasting temperature of 700 °C, roasting time of 30 min, four stage water leaching, liquid to solid ratio of 7 mL/g, leaching temperature of 90 °C and reaction time of 60 min. The diffraction peak of Na{sub 6}CaAl{sub 6}Si{sub 6}(CO{sub 3})O{sub 24}·2H{sub 2}O in red mud was decreased during the active roasting process, whereas the mineral phases of NaOH·H{sub 2}O and Na{sub 2}Ca(CO{sub 3}){sub 2} were appeared. The content of alkali obviously decreased and the grade of other elements increased during the process of active roasting and water leaching, which was in favor of next application process of red mud. The water leaching was controlled by internal diffusion of SCM and the apparent activation energy was 22.63 kJ/mol.

  2. Effect of Harsh or Mild Extraction of Soil on Pesticide Leaching to Groundwater.

    Science.gov (United States)

    Boesten, Jos J T I

    2016-07-01

    Assessment of leaching to groundwater is an important aspect of pesticide risk assessment. The first leaching tier usually consists of simulations with leaching scenarios based on pesticide-soil properties derived from laboratory studies. Because the extractability of pesticide residues in such studies decreases with time, the harshness of the extraction method influences these pesticide-soil properties. This study investigates the effect of using a mild or harsh extraction method on simulated leaching to groundwater with consideration of substances with a range of half-lives and organic matter sorption coefficient values for selected leaching scenarios. The model for linking the concentrations of the mild and the harsh systems was based on laboratory studies with two pesticides and a Dutch sandy soil and was tested against Canadian field studies with atrazine (6-chloro-2-ethyl-4-isopropyl-1,3,5-triazine-2,4-diamine). The degradation rate and the aged-sorption parameters of each "mild" soil-substance system were derived from a hypothetical laboratory incubation study using prescribed parameter values for the corresponding "harsh" soil-substance system. Simulations were performed for three European leaching scenarios (United Kingdom, France, Portugal). For the best-guess parameter set, the leaching concentrations of the harsh system were approximately equal to those of the mild system at leaching concentrations greater than 1 μg L and were at most approximately a factor of two higher than those of the mild systems at mild leaching concentrations between 0.01 and 0.1 μg L. However, an extreme parameter set led to harsh leaching concentrations that were at most approximately 10 times higher than the mild leaching concentrations at levels between 0.01 and 0.1 μg L. PMID:27380081

  3. Leaching of complex sulphide concentrate in acidic cupric chloride solutions

    Institute of Scientific and Technical Information of China (English)

    M. TCHOUMOU; M. ROYNETTE

    2007-01-01

    The chemical analysis of a complex sulphide concentrate by emission spectrometry and X-ray diffraction shows that it contains essentially copper, lead, zinc and iron in the form of chalcopyrite, sphalerite and galena. A small amount of pyrite is also present in the ore but does not be detected with X-ray diffraction. The cupric chloride leaching of the sulphide concentrate at various durations and solid/liquid ratios at 100 ℃ shows that the rate of dissolution of the ore is the fastest in the first several hours, and after 12 h it does not evolve significantly. If oxygen is excluded from the aqueous cupric chloride solution during the leaching experiment at 100 ℃, the pyrite in the ore will not be leached. The determination of principal dissolved metals in the leaching liquor by flame atomic absorption spectrometry, and the chemical analysis of solid residues by emission spectrometry and X-ray diffraction allow to conclude that the rate of dissolution of the minerals contained in the complex sulphide concentrate are in the order of galena>sphalerite>chalcopyrite.

  4. Leaching of irradiated light-water-reactor fuel in a simulated post-accident environment

    International Nuclear Information System (INIS)

    Personnel involved in cleanup operations following a light-water-reactor accident in which the fuel has been significantly damaged will have to consider the fission products that have leached from the fuel into the reactor water. Five samples of declad, irradiated fuel were leached in a borate solution that should approximate the post-accident conditions in a reactor. The resulting release of fission products was measured over the course of approx. 1 year. The radioactivity levels of the leaching solutions were converted into leach rates and fractional releases. Fractional releases are projected for 4 years following the start of leaching. These values can be used to estimate the radioactive content of the reactor water before cleanup operations begin. 25 figures, 4 tables

  5. Nitrate leaching from organic arable crop rotations is mostly determined by autumn field management

    DEFF Research Database (Denmark)

    Askegaard, M; Olesen, Jørgen E; Rasmussen, Ilse Ankjær;

    2011-01-01

    in the manured treatments the application rate was lower than crop demand. The results identify management of crop and soil during autumn as the main determinant of N leaching. Nitrate leaching was lowest for a catch crop soil cover during autumn and winter (avg. 20 kg N ha−1), a soil cover of weeds......Two main challenges facing organic arable farming are the supply of nitrogen (N) to the crop and the control of perennial weeds. Nitrate leaching from different organic arable crop rotations was investigated over three consecutive four-year crop rotations in a field experiment at three locations...... in Denmark (12 years in total). The experimental treatments were: (i) crop rotation, (ii) catch crop and (iii) animal manure. Nitrate leaching was estimated from measured soil nitrate concentration in ceramic suction cells and modelled drainage. There were significant effects on annual N leaching of location...

  6. Leaching of Glyphosate and Aminomethylphosphonic Acid from an Agricultural Field over a Twelve-Year Period

    DEFF Research Database (Denmark)

    Norgaard, Trine; Moldrup, Per; Ferré, Ty P A;

    2014-01-01

    The globally-used herbicide glyphosate (N-(phosphonomethyl)glycine) and its most frequently detected metabolite, aminomethylphosphonic acid (AMPA), were studied in a unique 12-year field-scale monitoring program. The leaching of glyphosate, AMPA, and soil particles were studied in a shallow...... drainage system beneath a 1.26 ha field. Five annual glyphosate applications were applied with different autumn application dates. Solute mass flux from the drain system following the five glyphosate applications were compared to determine how different factors affect the leaching of glyphosate, AMPA......, and particles. Glyphosate and AMPA leaching were highly event driven, controlled by the time and intensity of the first precipitation event after glyphosate application. A high similarity in time-accumulated curves for drainage and leached pesticide masses suggests near-constant drainage and leaching rates...

  7. Leaching of solutes from ion-exchange resins buried in Bandelier Tuff

    Energy Technology Data Exchange (ETDEWEB)

    Essington, E.H.; Fuentes, H.R.; Polzer, W.L.; Lopez, E.A.; Stallings, E.A.

    1986-10-01

    Prediction of solute transport at shallow land burial facilities requires a knowledge of the rates of release of solutes (source term) from the buried wastes and of those processes affecting transport through the surrounding media. The leaching (removal) of lithium, strontium, and cesium from a resin/tuff mixture (Bandelier Tuff) was conducted under unsaturated steady and unsteady (drainage) flow conditions in both laboratory columns and large-scale field caissons to approximate the conditions of buried contaminated-waste resins. Lithium was leached most rapidly and strontium least rapidly. Stopping the flow for a period of 40 to 60 days to create drainage (unsteady flow) conditions had very little effect on the concentrations of solutes leached from the resin/tuff layer. Leaching of these solutes in laboratory columns simulated the large-scale (caisson) leaching very well. Thus, laboratory studies may be reasonable predictors of leaching under certain large-scale field conditions. Also, leaching appears to be a kinetics-controlled process that, for the experimental conditions of this study, may be represented by simple first-order kinetics. Further work should concentrate on understanding the effect of environmental factors such as solute mixtures, concentrations, and temperature, as well as those mechanisms that control leaching of solutes. Also, the evaluation and development of alternative mathematical models for describing the source term are needed.

  8. Dynamics in simultaneous electro-generative leaching for sphalerite-MnO2

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The principle for the electro-generative leaching was applied to simultaneous leaching of sphalerite-MnO2. A galvanic system for the bio-electro-generative leaching was set up. The effects of grain size and temperature on rate of zinc extraction from sphalerite under the conditions of presence and absence ofAcidithiobacillusferrooxidans (A.ferrooxidans) were studied, respectively.The results show that with bacteria, the maximum extraction of zinc from the ores with grain size of 16.6 μm can reach 32.01% after leaching for 12 h, while to obtain the same extraction ratio in the traditional bio-leaching route (i.e. not electro-generative one) 10 d is needed to ore granules with same size. The unreacted shrinking core model was used for describing the reaction-relative and diffusion-relative phenomena presented in the process of the electro-generative leaching with and without bacteria, which is considered to be diffusion controlled. The activation energies of the anodic reaction for leaching system in the presence and absence of bacteria are 11.97 and 14.39 kJ/mol, respectively, indicating that leaching rate can be decreased by A. ferrooxidans. SEM was used to study the effect of A. ferrooxidans on the ores in the simultaneous electro-generative leaching, which indicates that the produced sulfur on the surface of the sulfides can be oxidized by A. ferrooxidans after bio-electro-generative leaching for 24 h, and the transferred charge due to the bacterial oxidation is up to 17.86%, which is an important part of the output electric quantity.

  9. Leaching kinetics of bottom ash waste as a source of calcium ions.

    Science.gov (United States)

    Koech, Lawrence; Everson, Ray; Neomagus, Hein; Rutto, Hilary

    2015-02-01

    Bottom ash is a waste material from coal-fired power plants, and it is known to contain elements that are potentially toxic at high concentration levels when disposed in landfills. This study investigates the use of bottom ash as a partial substitute sorbent for wet flue gas desulfurization (FGD) processes by focusing on its leaching kinetics in adipic acid. This was studied basing on the shrinking core model that was applied to the experimental data obtained by the authors presented at the International Conference on Industrial, Manufacturing, Automation and Mechanical Engineering, Johannesburg, South Africa, November 27-28, 2013) on dissolution of bottom ash. The leaching rate constant was obtained from different reaction variables, namely, temperature, pH, acid concentration, and solid-to-liquid ratio, that could affect the leaching process. The solid sample of bottom ash was characterized at different leaching periods using X-ray diffraction (XRD) and scanning electron microscopy (SEM). It was found that solid-to-liquid ratio had a significant effect on the leaching rate constant when compared with other variables. The leaching kinetics showed that diffusion through the product layer was the rate-controlling step during leaching, and the activation energy for the process was found to be 18.92 kJ/mol.

  10. Underground leaching of uranium ores

    International Nuclear Information System (INIS)

    Large amounts of low-grade U ore, not worth processing by conventional methods, are to be found at many sites in mine pillars, walls, and backfilling. Many proven deposits are not being mined because the geological conditions are difficult or the U ore is of relatively low grade. Factors such as radioactive emission, radon emanation, and the formation of radioactive dust give rise to health hazards. When U ores are treated above ground, enormous quantities of solid and liquid radioactive waste and mining spoil accumulate. The underground leaching of U is a fundamentally different kind of process. It is based on the selective dissolving of U at the place where it occurs by a chemical reagent; all that reaches the ground surface is a solution containing U, and after extraction of the U by sorption the reagent is used again. The main difficult and dangerous operations associated with conventional methods (excavation; extraction and crushing of the ore; storage of wastes) are avoided. Before underground leaching the ore formation has to be fractured and large ore bodies broken down into blocks by shrinkage stopping. These operations are carried out by advanced machinery and require the presence underground of only a few workers. If the ore is in seams, the only mining operation is the drilling of boreholes. The chemical reagent is introduced under pressure through one set of boreholes, while the U bearing solution is pumped out from another set. The process is monitored with the help of control boreholes. After extraction of the U by sorption, the reagent is ready to be used again. Very few operations are involved and insignificant amounts of dissolved U escape into the surrounding rock formations. Experience has shown that underground leaching reduces the final cost of the U metal, increases productivity, reduces capital expenditure, and radically improves working conditions

  11. The Theory of Caustics and Wave Front Singularities with Physical Applications

    OpenAIRE

    Ehlers, J.; Newman, E.

    2000-01-01

    This is intended as an introduction to and review of the theory of Lagrangian and Legendrian submanifolds and their associated maps developed by Arnold and his collaborators. The theory is illustrated by applications to Hamilton–Jacobi theory and the eikonal equation, with an emphasis on null surfaces and wave fronts and their associated caustics and singularities.

  12. Biological treatment of refinery spent caustics under halo-alkaline conditions

    NARCIS (Netherlands)

    Graaff, de M.; Bijmans, M.F.M.; Abbas, B.; Euverink, G.J.W.; Muyzer, G.; Janssen, A.J.H.

    2011-01-01

    The present research demonstrates the biological treatment of refinery sulfidic spent caustics in a continuously fed system under halo-alkaline conditions (i.e. pH 9.5; Na(+)= 0.8M). Experiments were performed in identical gas-lift bioreactors operated under aerobic conditions (80-90% saturation) at

  13. Structural evaluation of mixer pump installed in Tank 241-AN-107 for caustic addition project

    International Nuclear Information System (INIS)

    This report documents the structural analysis and evaluation of a mixer pump and caustic addition system to be used in Tank 107-AN. This pump will be installed in the central pump pit of this double- shell tank for the purpose of bringing the hydroxide ion concentration into compliance with Tank Farm operating specifications

  14. Caustic Agent Ingestion by a 1.5-Year-Old Boy.

    Science.gov (United States)

    Gharib, Behdad; Mohammadpour, Masoud; Yaghmaie, Bahareh; Sharifzadeh, Meisam; Mehdizadeh, Mehrzad; Zamani, Fatemeh; Edalatkhah, Rouhollah; Mohsenipour, Reihaneh

    2016-07-01

    We present a case of caustic ingestion by a 1.5-year-old boy. The caustic agent was drain opener which is a strong alkaline substance. Children in Iran and many other countries are still exposed to not "child proof" (child resistant packaging) toxic substance containers. Ingestion of caustic agents may lead to necrosis, perforation, and strictures. Substances that are ingested more frequently are liquid alkali material which causes severe, deep liquefaction necrosis. Common signs and symptoms of caustic agents are vomiting, drooling, refusal to drink, oral burns, stridor, hematemesis, dyspnea, dysphagia and abdominal pain. Even if no oropharyngeal lesion is seen, a significant esophageal injury which can lead to perforation and stricture cannot be ruled out. If abdominal pain or rigidity, substernal, chest or back pain exists, visceral perforation should be considered. The first thing to be checked is airway assessment. A lot of patients should be admitted to intensive care unit, and endoscopic evaluation, surgical intervention, long-term hospitalization, and worsening quality of life or among the complications. Preventive measures especially at the country level and approving proper legislation for obligating the related industries to produce child proof containers for house hold toxic products are the urgent measures to be followed by all of us. PMID:27424019

  15. Biological treatment of refinery spent caustics under halo-alkaline conditions

    NARCIS (Netherlands)

    M. de Graaff; M.F.M. Bijmans; B. Abbas; G.J.W. Euverink; G. Muijzer; A.J.H. Janssen

    2011-01-01

    The present research demonstrates the biological treatment of refinery sulfidic spent caustics in a continuously fed system under halo-alkaline conditions (i.e. pH 9.5; Na+ = 0.8 M). Experiments were performed in identical gas-lift bioreactors operated under aerobic conditions (80-90% saturation) at

  16. Biological treatment of refinery spent caustics under halo-alkaline conditions

    NARCIS (Netherlands)

    Graaff, Marco de; Bijmans, Martijn F.M.; Abbas, Ben; Euverink, Gert-J.W.; Muyzer, Gerard; Janssen, Albert J.H.

    2011-01-01

    The present research demonstrates the biological treatment of refinery sulfidic spent caustics in a continuously fed system under halo-alkaline conditions (i.e. pH 9.5; Na+ = 0.8 M). Experiments were performed in identical gas-lift bioreactors operated under aerobic conditions (80–90% saturation) at

  17. Novel Electrochemical Treatment of Spent Caustic from the Hydrocarbon Industry Using Ti/BDD

    Directory of Open Access Journals (Sweden)

    Alejandro Medel

    2015-01-01

    Full Text Available During the crude oil refining process, NaOH solutions are used to remove H2S, H2Saq, and sulfur compounds from different hydrocarbon streams. The residues obtained are called “spent caustics.” These residues can be mixed with those obtained in other processes, adding to its chemical composition naphthenic acids and phenolic compounds, resulting in one of the most dangerous industrial residues. In this study, the use of electrochemical technology (ET, using BDD with Ti as substrate (Ti/BDD, is evaluated in electrolysis of spent caustic mixtures, obtained through individual samples from different refineries. In this way, the Ti/BDD’s capability of carrying out the electrochemical destruction of spent caustics in an acidic medium is evaluated having as key process a chemical pretreatment phase. The potential production of •OHs, as the main reactive oxygen species electrogenerated over Ti/BDD surface, was evaluated in HCl and H2SO4 through fluorescence spectroscopy, demonstrating the reaction medium’s influence on its production. The results show that the hydrocarbon industry spent caustics can be mineralized to CO2 and water, driving the use of ET and of the Ti/BDD to solve a real problem, whose potential and negative impact on the environment and on human health is and has been the environmental agencies’ main focus.

  18. Method of continuous pressure leaching of ores

    International Nuclear Information System (INIS)

    Ore leaching, especially suspensions of ground ore or fine ore fractions from physical treatment was divided into two operations. The former, i.e., ore mixing with technical grade concentrated sulfuric acid proceeded in a separate mixer. The mixture was then transported into an autoclave where the actual leaching proceeded for 2 to 4 hours. The extracted mixture was discharged through the autoclave bottom. The leaching autoclave used can be without any inner structures. The separation of mixing from the actual leaching allows processing ores with high levels of clay components, increasing operating reliability of the facility, reducing consumption of special structural materials and energy, and increasing process efficiency. (E.S.)

  19. 从铜阳极泥中氧压浸出有价金属试验研究%Leaching of Valuable Metals From Copper Anode Slime by Oxygen Pressure-Acid Leaching Process

    Institute of Scientific and Technical Information of China (English)

    蔡创开; 庄荣传; 林鸿汉

    2015-01-01

    Leaching of valuable metals from copper anode slime by three oxygen pressure process was investigated .The distribution of copper ,tellurium ,selenium and silver in the processes were examined . The results show that by the direct oxygen pressure-acid leaching process ,selenium is partially leached out which is not conducive to enrich of selenium in leaching residues .The process of water leaching-oxygen pressure alkali leaching is lengthy and complex ,the silver is dispersed in the leaching solution . By water leaching-oxygen pressure acid leaching process ,under the conditions of temperature of 130℃ ,oxygen pressure of 0 .8 M Pa ,the leaching rate of copper ,tellurium and selenium are 98 .3% ,46 .8%and 0 .11% ,respectively ,and the silver is concentrated in leaching residues .So the water leaching-oxygen pressure acid leaching process is recommended to further research .%研究了采用3种加压氧化方式从铜阳极泥中浸出有价金属 ,考察了阳极泥中铜、碲、硒、银的走向.结果表明 :直接氧压酸浸 ,阳极泥中的硒被部分浸出 ,不利于集中回收 ;氧压碱浸工艺流程长 ,工艺复杂 ,银被分散 ;水浸—氧压酸浸过程中 ,控制体系温度130 ℃ ,氧压0 .8 M Pa ,铜浸出率达98 .3% ,碲浸出率为46 .8% ,硒浸出率仅0 .11% ,银集中在渣中 ,有利于下一步集中回收.3种工艺中 ,以水浸—氧压酸浸效果最佳.

  20. A geochemical module for "AMDTreat" to compute caustic quantity, effluent quantity, and sludge volume

    Science.gov (United States)

    Cravotta, Charles A., III; Parkhurst, David L.; Means, Brent P; McKenzie, Bob; Morris, Harry; Arthur, Bill

    2010-01-01

    Treatment with caustic chemicals typically is used to increase pH and decrease concentrations of dissolved aluminum, iron, and/or manganese in largevolume, metal-laden discharges from active coal mines. Generally, aluminum and iron can be removed effectively at near-neutral pH (6 to 8), whereas active manganese removal requires treatment to alkaline pH (~10). The treatment cost depends on the specific chemical used (NaOH, CaO, Ca(OH)2, Na2CO3, or NH3) and increases with the quantities of chemical added and sludge produced. The pH and metals concentrations do not change linearly with the amount of chemical added. Consequently, the amount of caustic chemical needed to achieve a target pH and the corresponding effluent composition and sludge volume can not be accurately determined without empirical titration data or the application of geochemical models to simulate the titration of the discharge water with caustic chemical(s). The AMDTreat computer program (http://amd.osmre.gov/ ) is widely used to compute costs for treatment of coal-mine drainage. Although AMDTreat can use results of empirical titration with industrial grade caustic chemicals to compute chemical costs for treatment of net-acidic or net-alkaline mine drainage, such data are rarely available. To improve the capability of AMDTreat to estimate (1) the quantity and cost of caustic chemicals to attain a target pH, (2) the concentrations of dissolved metals in treated effluent, and (3) the volume of sludge produced by the treatment, a titration simulation is being developed using the geochemical program PHREEQC (wwwbrr.cr.usgs.gov/projects/GWC_coupled/phreeqc/) that will be coupled as a module to AMDTreat. The simulated titration results can be compared with or used in place of empirical titration data to estimate chemical quantities and costs. This paper describes the development, evaluation, and potential utilization of the PHREEQC titration module for AMDTreat.

  1. Role of microstructure in caustic stress corrosion cracking of Alloy 690

    International Nuclear Information System (INIS)

    Alloy 690 has been selected for nuclear heat transport system tubing application in recent commercial reactor plants due to its resistance to multiple types of corrosion attack. Typical corn final heat treatments for this material are a mill-anneal (MA, approximately 1,070 C) to completely dissolve the carbides and develop the final grain structure plus a thermal treatment (TT, approximately 700 C) to precipitate carbides at the grain boundaries. Tubing with grain boundary carbides and no or few intragranular carbides has been found resistant to intergranular stress corrosion cracking (IGSCC) in caustic environments. In this work, first, Alloy 690 plate was subjected to a variety of MA and MA-TT heat treatments to create microstructures of carbide-decorated grain boundaries and undecorated boundaries. Caustic IGSCC test results were consistent with tubing data. Second, experiments were conducted to understand the mechanism by which caustic-corrosion resistance is imparted to Alloy 690 by grain boundary carbides. Tubing with a fully-developed MA-TT carbide microstructure was strained and heat-treated to create a mixed microstructure of new grain boundaries with no carbide precipitate decoration, intermixed with intragranular carbide strings from prior grain boundaries. Caustic SCC performance of this material was identical to that of material with the MA-TT carbide-decorated grain boundaries. This work suggests that the fundamental cause of good IGSCC resistance of MA-TT Alloy 690 in caustic does not derive solely from grain boundary carbides. It is suggested that matrix strength, as measured by yield stress, could be a controlling factor

  2. Study on indium leaching from mechanically activated hard zinc residue

    Directory of Open Access Journals (Sweden)

    Yao J.H.

    2011-01-01

    Full Text Available In this study, changes in physicochemical properties and leachability of indium from mechanically activated hard zinc residue by planetary mill were investigated. The results showed that mechanical activation increased specific surface area, reaction activity of hard zinc residue, and decreased its particle size, which had a positive effect on indium extraction from hard zinc residue in hydrochloric acid solution. Kinetics of indium leaching from unmilled and activated hard zinc residue were also investigated, respectively. It was found that temperature had an obvious effect on indium leaching rate. Two different kinetic models corresponding to reactions which are diffusion controlled, [1-(1- x1/3]2=kt and (1-2x/3-(1-x2/3=kt were used to describe the kinetics of indium leaching from unmilled sample and activated sample, respectively. Their activation energies were determined to be 17.89 kJ/mol (umilled and 11.65 kJ/mol (activated within the temperature range of 30°C to 90°C, which is characteristic for a diffusion controlled process. The values of activation energy demonstrated that the leaching reaction of indium became less sensitive to temperature after hard zinc residue mechanically activated by planetary mill.

  3. Kinetics and leaching behaviors of aluminum from pharmaceutical blisters in sodium hydroxide solution

    Institute of Scientific and Technical Information of China (English)

    王重庆; 王晖; 顾帼华; 符剑刚; 刘又年

    2015-01-01

    A hydrometallurgical process was developed for recycling pharmaceutical blisters. Leaching aluminum from pharmaceutical blisters using sodium hydroxide (NaOH) solutions was investigated with respect to leaching behaviors and kinetics. A L9(34) orthogonal design of experiments suggests that the most significant factor is NaOH concentration followed by temperature and leaching time. Factorial experiments demonstrate that the leaching rate of aluminum increases with increasing of the factors. The optimum conditions are temperature of 70 °C, leaching time of 20 min, NaOH concentration of 1.25 mol/L, liquid-to-solid mass ratio of 15:1 and agitation speed of 400 r/min. Under optimum conditions, the leaching rate is up to 100%, implying that aluminum and polyvinyl chloride (PVC) plastic in pharmaceutical blisters are separated completely. Kinetics of leaching aluminum is best described by the product layer diffusion control model, and the activation energy is calculated to be 19.26 kJ/mol.

  4. Leach tests on grouts made with actual and trace metal-spiked synthetic phosphate/sulfate waste

    International Nuclear Information System (INIS)

    Pacific Northwest Laboratory conducted experiments to produce empirical leach rate data for phosphate-sulfate waste (PSW) grout. Effective diffusivities were measured for various radionuclides (90Sr, 99Tc, 14C, 129I, 137Cs, 60Co, 54Mn, and U), stable major components (NO3-, SO42-, H3BO3, K and Na) and the trace constituents Ag, As, Cd, Hg, Pb, and Se. Two types of leach tests were used on samples of actual PSW grout and synthetic PSW grout: the American Nuclear Society (ANS) 16.1 intermittent replacement leach test and a static leach test. Grout produced from both synthetic and real PSW showed low leach rates for the trace metal constituents and most of the waste radionuclides. Many of the spiked trace metals and radionuclides were not detected in any leachates. None of the effluents contained measurable quantities of 137Cs, 60Co, 54Mn, 109Cd, 51Cr, 210Pb, 203Hg, or As. For those trace species with detectable leach rates, 125I appeared to have the greatest leach rate, followed by 99Tc, 75Se, and finally U, 14C, and 110mAg. Leach rates for nitrate are between those for I and Tc, but there is much scatter in the nitrate data because of the very low nitrate inventory. 32 refs., 6 figs., 15 tabs

  5. Comparative Study on the Leaching Dynamic Properties of Five Kinds of Microparticulate forms of Vitamin B1

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    With an aim to reduce leaching of water-soluble vitamins, the leaching properties of five kinds of microparticulate forms of vitamin B1 are investigated by means of dynamic system. These microparticles include: alginate and alginate-CMC microcapsules prepared by emulsion coacervation process (ECP), alginate and gelatin microcapsules prepared by spray-drying process (SDP), and alginate microbound. The results show these five microparticulate forms of VB1 can reduce leaching significantly compared to crystalline form VB1, and the leaching rates at different intervals, diameters and encapsulation efficiencies (EE) are significantly different among all kinds of microparticles (ANOVA, P<0.05). The leaching properties of the five microparticles are in accord with Higuchi equation. Based on the regression equation, the half loss time (T50) is determined.In conclusion, the alginate-CMC microencapsule is a potential tool to reduce leaching of water-soluble vitamins.

  6. Simultaneous Pressure Oxidation Leaching of Zinc Sulfide Concentrate and Neutral Leaching Residue%闪锌矿与中性浸出渣合并氧压酸浸

    Institute of Scientific and Technical Information of China (English)

    梁铎强; 王吉坤; 周廷熙; 张怀伟

    2009-01-01

    硫化锌精矿和由传统流程得到的中浸渣混在一块,对其进行了浸出的小型试验.试验在不同的条件下进行,以考察影响浸出的各种因素,包括浸出温度、浸出时间、氧分压和搅拌速度.试验在一个两升的高压釜内进行.试验结果表明了硫化锌精矿和中浸渣能相到促进浸出,但只有在一定的浸出条件下这种耦合作用才表现得比较明显.研究过程中一些机理也得到了证实.最后为了后面的扩大试验提供了关键的浸出条件:浸出温度135℃;浸出时间2h;氧分压0.8MPa;初始酸度120g/L.%Lab-scale simultaneous leaching of zinc sulfide concentrate and neutral leaching residue obtained by traditional roast-leachelectrowin (RLE) were performed in various conditions to investigate leaching variables such as leaching temperature, leaching duration, oxygen partial pressure and stirring rate. Experiments were carried out in a 2-liter autoclave. Experimental results show that zinc sulfide concentrate and the neutral leaching residue help each other to leach in such simultaneous leaching experiments, but the coupling effect occurs obviously only in a given leaching conditions. In this work some mechanisms are proved in the experiments. For the sake of subsequent scaleup experiment,the reasonable condition of simultaneous leaching is given as follows,leaching temperature,135%;leaching duration,2hr;oxygen partial pressure,0.8MPa; initial acidity,120g/l.

  7. Column leaching of lanthanides from Abu Tartur phosphate ore with kinetic study

    Institute of Scientific and Technical Information of China (English)

    A.T.; Kandil; M.M.; Aly; E.M.; Moussa; A.M.; Kamel; M.M.; Gouda; M.N.; Kouraim

    2010-01-01

    The dynamic leaching of lanthanides from a west desert phosphate ore, Egypt (Abu Tartur) by hydrochloric acid, nitric acid and sulfuric acid solutions was investigated in this study as a function of acid concentration, flow rate and the presence of some additives such as boric acid. Also the kinetics of leaching of lanthanides was investigated as a function of temperature. It was found that the leaching process could be described by a shrinking-core model, with activation energy about 5.9, 13.8 and 21.9 kJ/...

  8. Extraction of Alumina from Coal Fly Ash with Sulfuric Acid Leaching Method

    Institute of Scientific and Technical Information of China (English)

    李来时; 吴玉胜; 刘瑛瑛; 翟玉春

    2011-01-01

    Coarse γ-Al2O3 powder was prepared through acid leaching, solid-liquid separation, crystallizing and aluminum sulfate decomposing processes using coal fly ash and concentrated sulfuric acid as raw materials. The metallurgy level Al2O3 can be obtained by disposing coarse γ-Al2O3 powder with Bayer process. The optimum conditions of acid leaching process were determined by experiments. The extraction rate of Al2O3 can be stabilized at about 87% under these conditions. The thermodynamics and kinetics of sulfuric acid leaching process were studied with irreversible thermodynamics.

  9. Use of Polyphosphate to Decrease Uranium Leaching in Hanford 300 Area Smear Zone Sediments

    Energy Technology Data Exchange (ETDEWEB)

    Szecsody, James E.; Zhong, Lirong; Oostrom, Martinus; Vermeul, Vincent R.; Fruchter, Jonathan S.; Williams, Mark D.

    2012-09-30

    The primary objective of this study is to summarize the laboratory investigations performed to evaluate short- and long-term effects of phosphate treatment on uranium leaching from 300 area smear zone sediments. Column studies were used to compare uranium leaching in phosphate-treated to untreated sediments over a year with multiple stop flow events to evaluate longevity of the uranium leaching rate and mass. A secondary objective was to compare polyphosphate injection, polyphosphate/xanthan injection, and polyphosphate infiltration technologies that deliver phosphate to sediment.

  10. Experimental Study of the Rhizobium and Iron Oxide Thiobacillus for Heap Leaching of Zinc Leaching Slag%根瘤菌与氧化铁硫杆菌堆浸锌浸出渣的试验研究

    Institute of Scientific and Technical Information of China (English)

    李勇; 邓兴; 金开胜; 杨光棣

    2012-01-01

    This paper adopts the rhizobium and thiobaeillus ferrooxidans respectively for heap leaching processing of hydrometallurgy of zinc leaching residue. Through the treatment of rhizobium with thiobacillus ferrooxidans, zinc leaching residue of zinc leaching rate is compared. The test results indicate that rhizobium treatment of zinc leaching residue of zinc leaching rate reaches 24.12 % and thiobacillus ferrooxidans treatment of zinc leaching residue of zinc leaching rate reaches 33.86 %. Treatment rate by thiobacillus ferrooxidans was significantly higher than that of rhizobium.%本文采用根瘤菌与氧化铁硫杆菌分别堆浸处理湿法冶金的锌浸出渣,通过比较根瘤菌与氧化铁硫杆菌处理的锌浸出渣的锌浸出率。试验结果表明,根瘤菌处理锌浸出渣锌浸出率达到了24.12%,而氧化铁硫杆菌处理的锌浸出渣锌浸出率达到了33.86%,氧化铁硫杆菌处理锌浸出渣的锌浸出率明显高于根瘤菌。

  11. Leaching behavior of copper from waste printed circuit boards with Brønsted acidic ionic liquid

    International Nuclear Information System (INIS)

    Highlights: • A Brønsted acidic ILs was used to leach Cu from WPCBs for the first time. • The particle size of WPCBs has significant influence on Cu leaching rate. • Cu leaching rate was higher than 99% under the optimum leaching conditions. • The leaching process can be modeled with shrinking core model, and the Ea was 25.36 kJ/mol. - Abstract: In this work, a Brønsted acidic ionic liquid, 1-butyl-3-methyl-imidazolium hydrogen sulfate ([bmim]HSO4), was used to leach copper from waste printed circuit boards (WPCBs, mounted with electronic components) for the first time, and the leaching behavior of copper was discussed in detail. The results showed that after the pre-treatment, the metal distributions were different with the particle size: Cu, Zn and Al increased with the increasing particle size; while Ni, Sn and Pb were in the contrary. And the particle size has significant influence on copper leaching rate. Copper leaching rate was higher than 99%, almost 100%, when 1 g WPCBs powder was leached under the optimum conditions: particle size of 0.1–0.25 mm, 25 mL 80% (v/v) ionic liquid, 10 mL 30% hydrogen peroxide, solid/liquid ratio of 1/25, 70 °C and 2 h. Copper leaching by [bmim]HSO4 can be modeled with the shrinking core model, controlled by diffusion through a solid product layer, and the kinetic apparent activation energy has been calculated to be 25.36 kJ/mol

  12. COMPARE AND ANALYSES OF OPTIMIZED R-LEACH WITH LEACH ALGORITHM IN WSN

    Directory of Open Access Journals (Sweden)

    Tarun Sharma

    2015-11-01

    Full Text Available Wireless sensor networks are composed of numerous small charge, little power devices with sensing, local processing and wireless communication capabilities. Minimizing energy consumption and maximizing network lifespan are significant issues in the design of routing protocols for sensor networks. In this paper, we analyses the efficiency of LEACH protocol in extending the existence for energy-constrained wireless sensor networks. Based on LEACH protocol, an enhanced protocol termed as R- LEACH is proposed which aims to diminish energy consumption within the wireless sensor networks. The simulation results suggest R-LEACH protocol could equilibrium network energy consumption and extend the network lifecycle more successfully as compared to LEACH.

  13. Study on Leaching of Hexavalent Chromium from Hardened Concretes Using Tank Leaching Test

    OpenAIRE

    Takahashi, Shigeru; Sakai, Etsuo; Sugiyama, Takafumi

    2007-01-01

    Tank leaching tests were carried out to investigate the behavior of leaching trace elements from monolith samples. This study consists of two series, and the trace element used was hexavalent chromium. In Series I, the influence of the leachant/surface area of the specimen (L/S ratio) on the leaching amount was investigated. The leaching amount was found to increase with the amount of worked water. This shows that any L/S ratio can be selected in the tank leaching test. In Series II, th...

  14. Atrazine leaching from biochar-amended soils.

    Science.gov (United States)

    Delwiche, Kyle B; Lehmann, Johannes; Walter, M Todd

    2014-01-01

    The herbicide atrazine is used extensively throughout the United States, and is a widespread groundwater and surface water contaminant. Biochar has been shown to strongly sorb organic compounds and could be used to reduce atrazine leaching. We used lab and field experiments to determine biochar impacts on atrazine leaching under increasingly heterogeneous soil conditions. Application of pine chip biochar (commercially pyrolyzed between 300 and 550 °C) reduced cumulative atrazine leaching by 52% in homogenized (packed) soil columns (p=0.0298). Biochar additions in undisturbed soil columns did not significantly (p>0.05) reduce atrazine leaching. Mean peak groundwater atrazine concentrations were 53% lower in a field experiment after additions of 10 t ha(-1) acidified biochar (p=0.0056) relative to no biochar additions. Equivalent peat applications by dry mass had no effect on atrazine leaching. Plots receiving a peat-biochar mixture showed no reduction, suggesting that the peat organic matter may compete with atrazine for biochar sorption sites. Several individual measurement values outside the 99% confidence interval in perched groundwater concentrations indicate that macropore structure could contribute to rare, large leaching events that are not effectively reduced by biochar. We conclude that biochar application has the potential to decrease peak atrazine leaching, but heterogeneous soil conditions, especially preferential flow paths, may reduce this impact. Long-term atrazine leaching reductions are also uncertain.

  15. Atrazine leaching from biochar-amended soils.

    Science.gov (United States)

    Delwiche, Kyle B; Lehmann, Johannes; Walter, M Todd

    2014-01-01

    The herbicide atrazine is used extensively throughout the United States, and is a widespread groundwater and surface water contaminant. Biochar has been shown to strongly sorb organic compounds and could be used to reduce atrazine leaching. We used lab and field experiments to determine biochar impacts on atrazine leaching under increasingly heterogeneous soil conditions. Application of pine chip biochar (commercially pyrolyzed between 300 and 550 °C) reduced cumulative atrazine leaching by 52% in homogenized (packed) soil columns (p=0.0298). Biochar additions in undisturbed soil columns did not significantly (p>0.05) reduce atrazine leaching. Mean peak groundwater atrazine concentrations were 53% lower in a field experiment after additions of 10 t ha(-1) acidified biochar (p=0.0056) relative to no biochar additions. Equivalent peat applications by dry mass had no effect on atrazine leaching. Plots receiving a peat-biochar mixture showed no reduction, suggesting that the peat organic matter may compete with atrazine for biochar sorption sites. Several individual measurement values outside the 99% confidence interval in perched groundwater concentrations indicate that macropore structure could contribute to rare, large leaching events that are not effectively reduced by biochar. We conclude that biochar application has the potential to decrease peak atrazine leaching, but heterogeneous soil conditions, especially preferential flow paths, may reduce this impact. Long-term atrazine leaching reductions are also uncertain. PMID:24129000

  16. Direct Causticizing for Black Liquor Gasification in a Circulating Fluidized Bed

    Energy Technology Data Exchange (ETDEWEB)

    Scott Sinquefield; Xiaoyan Zeng, Alan Ball

    2010-03-02

    Gasification of black liquor (BLG) has distinct advantages over direct combustion in Tomlinson recovery boilers. In this project we seek to resolve causticizing issues in order to make pressurized BLG even more efficient and cost-effective. One advantage of BLG is that the inherent partial separation of sulfur and sodium during gasification lends itself to the use of proven high yield variants to conventional kraft pulping which require just such a separation. Processes such as polysulfide, split sulfidity, ASAQ, and MSSAQ can increase pulp yield from 1% to 10% over conventional kraft but require varying degrees of sulfur/sodium separation, which requires additional [and costly] processing in a conventional Tomlinson recovery process. However during gasification, the sulfur is partitioned between the gas and smelt phases, while the sodium all leaves in the smelt; thus creating the opportunity to produce sulfur-rich and sulfur-lean white liquors for specialty pulping processes. A second major incentive of BLG is the production of a combustible product gas, rich in H2 and CO. This product gas (a.k.a. “syngas”) can be used in gas turbines for combined cycle power generation (which is twice as efficient as the steam cycle alone), or it can be used as a precursor to form liquid fuels, such as dimethyl ether or Fischer Tropsh diesel. There is drawback to BLG, which has the potential to become a third major incentive if this work is successful. The causticizing load is greater for gasification of black liquor than for combustion in a Tomlinson boiler. So implementing BLG in an existing mill would require costly increases to the causticizing capacity. In situ causticizing [within the gasifier] would handle the entire causticizing load and therefore eliminate the lime cycle entirely. Previous work by the author and others has shown that titanate direct causticizing (i.e. in situ) works quite well for high-temperature BLG (950°C), but was limited to pressures below

  17. 新型硫化物助剂强化浸出酸浸渣中铁的研究%Study on Intensified Leaching of Ferric Iron from Acid-leach Residues Using Sulfide as a Novel Leaching Agent

    Institute of Scientific and Technical Information of China (English)

    金程; 赵颖华; 李登新

    2011-01-01

    采用硫化物作助剂强化溶浸酸浸渣中的氧化铁.分别进行了助浸剂用量、硫酸用量、时间、温度、液固比等条件试验,考察其对酸溶效果的影响,结果表明:当助剂与渣质量比为0.69:1,硫酸过剩系数为1.4,起始液固比为2:1,搅拌速度为1 300 r/min时,在95℃下反应2h,铁的浸取率可以达到89.2%,助剂中锌的浸出率为90.2%,尾渣易于进一步提金.与现行技术条件相比,硫酸用量大大减少,工艺简单,能耗低.%Taking sulfide as a leaching agent, tests were conducted on the intensified-leaching of iron oxide from acid-leach residue. Influence of different factors, such as consumption of leaching agent, dosage of sulfuric acid, leaching time and temperature, as well as liquid-solid ratio, on the leaching effect was investigated. Results show that iron leaching rate reaches 89.2% and the leach rate of zinc from leaching agent is 90.2% under the following conditions of the initial liquid/solid ratio being 1'-1, the mass ratio of leaching agent to residue being 0. 69: 1, excess coefficient of sulfuric acid being 1.4, with a stirring rate at 1 300 r/min and reaction at the temperature of 95 X. For 2 h. The tailings obtained can also be used for further gold-extraction. This process is simple with low energy consumption compared with the existing technology, and sulfuric acid consumption is greatly reduced.

  18. PRESERVATIVE LEACHING FROM WEATHERED CCA-TREATED WOOD

    Science.gov (United States)

    Disposal of discarded CCA-treated wood in landfills raises concerns with respect to leaching of preservative compounds. When unweathered CCA-treated wood is leached using the toxicity characteristic leaching procedure (TCLP), arsenic concentrations exceed the toxicity characteris...

  19. Pesticide sorption and leaching potential on three Hawaiian soils.

    Science.gov (United States)

    Hall, Kathleen E; Ray, Chittaranjan; Ki, Seo Jin; Spokas, Kurt A; Koskinen, William C

    2015-08-15

    On the Hawaiian Islands, groundwater is the principal source of potable water and contamination of this key resource by pesticides is of great concern. To evaluate the leaching potential of four weak acid herbicides [aminocyclopyrachlor, picloram, metsulfuron-methyl, biologically active diketonitrile degradate of isoxaflutole (DKN)] and two neutral non-ionizable herbicides [oxyfluorfen, alachlor], their sorption coefficients were determined on three prevalent soils from the island of Oahu. Metsulfuron-methyl, aminocylcopyrachlor, picloram, and DKN were relatively low sorbing herbicides (K(oc) = 3-53 mL g(-1)), alachlor was intermediate (K(oc) = 120-150 mL g(-1)), and oxyfluorfen sorbed very strongly to the three soils (K(oc) > 12,000 mL g(-1)). Following determination of K(oc) values, the groundwater ubiquity score (GUS) indices for these compounds were calculated to predicted their behavior with the Comprehensive Leaching Risk Assessment System (CLEARS; Tier-1 methodology for Hawaii). Metsulfuron-methyl, aminocyclopyrachlor, picloram, and DKN would be categorized as likely leachers in all three Hawaiian soils, indicating a high risk of groundwater contamination across the island of Oahu. In contrast, oxyfluorfen, regardless of the degradation rate, would possess a low and acceptable leaching risk due to its high sorption on all three soils. The leaching potential of alachlor was more difficult to classify, with a GUS value between 1.8 and 2.8. In addition, four different biochar amendments to these soils did not significantly alter their sorption capacities for aminocyclopyrachlor, indicating a relatively low impact of black carbon additions from geologic volcanic inputs of black carbon. Due to the fact that pesticide environmental risks are chiefly dependent on local soil characteristics, this work has demonstrated that once soil specific sorption parameters are known one can assess the potential pesticide leaching risks. PMID:26024994

  20. The use of natural zeolites for radioactive waste treatment. Studies on leaching from zeolite/cement composites

    International Nuclear Information System (INIS)

    Samples of the natural zeolites chabazite, clinoptilolite and a clinoptilolite-rich tuff, were loaded with the isotope 137Cs. Composites of these labeled materials were made with cement and blast furnace slag. Standard leaching experiments were carried out with synthetic sea, ground and 'pond' waters, as well as distilled water. Rates of leaching were calculated and compared to similar systems. (author)

  1. Study on leaching rare earths from bastnaesite treated by calcification transition

    Institute of Scientific and Technical Information of China (English)

    黄宇坤; 张廷安; 豆志河; 刘江; 唐方方

    2014-01-01

    Extracting rare earths from bastnaesite concentrate treated by calcification transition was studied through the single factor test and XRD patterns of bastnaesite after calcification and slags after leaching in HCl solution. And the effects of the main calcified parameters such as temperature, liquid/solid and calcified time on transition performance of bastnaesite were investigated. It was found that under the optimal conditions of calcification temperature of 250 ºC, liquid/solid of 20 mL/g, calcification time of 180 min, the highest leaching rate of rare earth were obtained, with the leaching ratio of rare earths 83.70%and Ce 77.01%, La 90.55%, Nd 92.03%, respectively;loss rates of fluorine with different calcification conditions were always less than 1%and XRD patterns of cal-cification slags and leaching slags showed that fluorine existed in the form of CaF2.

  2. Leaching of tritium from a cement composite

    International Nuclear Information System (INIS)

    Leaching of tritium from cement composites into an aqueous phase has been studied to evaluate the safety of incorporation of the tritiated liquid waste into cement. Leaching tests were performed by the method recommended by the International Atomic Energy Agency. The Leaching fraction was measured as functions of waste-cement ratio (Wa/C), temperature of leachant and curing time. The tritium leachability of cement in the long term test follows the order: alumina cement portland cement slag cement. The fraction of tritium leached increases with increasing Wa/C and temperature and decreasing curing period. A deionized water as a leachant gives a slightly higher leachability than synthetic sea water. The amount leached of tritium from a 200 l drum size specimen was estimated on the basis of the above results. (author)

  3. Rule of oxygen transmission in dump leaching

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    According to the chemical equations, the flux and concentration of oxygen required during bacterial leaching sulfuric mineral were investigated; the rule of air bubble transmitted in granular was researched in the Dump Leaching Plant of Dexing Copper Mine. The results show that lack of oxygen in dump leaching is the critical factor of restricting leaching reaction. Pyrite is the primary oxygen-consuming mineral in bioleaching. When its content is too high, it needs a great deal of oxygen for reaction and competes for the finite oxygen with objective minerals, and thus the leaching velocity decreases greatly. The average size of ore particles and diameter of bubbles are the key parameters affecting the mass transfer coefficient. Reverse analysis was adopted, and it shows that 44.8 m3 air per unit ore can meet the requirement of production if the molar ratio of pyrite to chalcopyrite is 10.

  4. LEACH Algorithm Based on Load Balancing

    Directory of Open Access Journals (Sweden)

    Wangang Wang

    2013-09-01

    Full Text Available This paper discusses advantages of LEACH Algorithm and the existing improved model which takes the famous hierarchy clustering routing protocol LEACH Algorithm as researching object. Then the paper indicates the problem that in the algorithm capacity factor of cluster head node is not taken into account leading the structure of clusters to be not so reasonable. This research discusses an energy-uniform cluster and cluster head selecting mechanism in which “Pseudo cluster head” concept is introduced in order to coordinate with “Load Monitor” Mechanism and “Load Leisure” Mechanism to maintain load balancing of cluster head character and stability of network topology. On the basis of LEACH Protocol improving algorithm of LEACH-C, CEFL and DCHS. NS2 simulation instrument is applied to do simulation analysis on the improved algorithm. Simulation result shows that LEACH-P Protocol effectively increase energy utilization efficiency, lengthens network lifetime and balances network load.  

  5. Microbial leaching of marmatite by Acidithiobacillus ferrooxidans and Acidithiobacillus thiooxidans

    Institute of Scientific and Technical Information of China (English)

    WANG Jun; QIU Guan-zhou; QIN Wen-qing; ZHANG Yan-sheng

    2006-01-01

    The bioleaching of marmatite in shaken flasks was studied. After leaching for 29 days, the leaching ratio of zinc was 91%.Three kinds of bacteria, mixture-based bacteria, 9K-based bacteria and sulfur-based bacteria were used in marmatite leaching, of which the mixture-based bacteria have the best leaching result while the sulfur-based bacteria have the worst. By analyzing the leaching residue using SEM and EDXA, the marmatite leaching mechanism was discussed.

  6. Gold Recovery by Chloridization Leaching of Lead Anode Slime%氯化浸出铅阳极泥回收金的研究

    Institute of Scientific and Technical Information of China (English)

    李怀仁; 陈家辉; 徐庆鑫; 和晓才; 翟中标

    2011-01-01

    The lead anode slime is treated by hydrometallurgy in order to recover gold. The results indicate that the leaching of copper is the main influencing factor in impurity -reduction acid. On the condition that the temperature is 65 ℃HC1 concentration is 2. 9 mol/L, NaCl concentration is 1. 3 mol/L and H2SO4 concentration is 0. 3 mol/L, the copper leaching rate is 92. 03 % , and the impurities are effectively removed. In the process of chloride leaching of gold, the temperature and the amount of NaC103 have obvious impact on the leaching rate of gold. With the increase of them, the gold leaching rate is improved notably. When the temperature is above 80 ℃, NaClO3 amount is greater than 12. 5% and H2SO4 concentration is 2.9 mol/L, the leaching rate of gold is higher than 98% .

  7. Best Management Practices for Minimizing Nitrate Leaching from Container-Grown Nurseries

    OpenAIRE

    Jianjun Chen; Yingfeng Huang; Russell D. Caldwell

    2001-01-01

    Containerized plant production represents an extremely intensive agricultural practice; 40,000 to 300,000 containers may occupy one acre of surface area to which a large amount of chemical fertilizer is applied. Currently, recommended fertilizer application rates for the production of containerized nursery ornamental plants are in excess of plant requirements, and up to 50% of the applied fertilizers may run off or be leached from containers. Among the nutrients leached or allowed to runoff, ...

  8. Evaluation of six pesticides leaching indexes using field data of herbicide application in Casablanca Valley, Chile.

    Science.gov (United States)

    Kogan, M; Rojas, S; Gómez, P; Suárez, F; Muñoz, J F; Alister, C

    2007-01-01

    A field study was performed to evaluate the accuracy of six pesticide screening leaching indexes for herbicide movement. Adsorption, dissipation and soil movement were studied in a vineyard in a sandy loam soil during 2005 season. Simazine, diuron, pendimethalin, oxyfluorfen and flumioxazin were applied to bare soil at rates commonly used, and their soil concentrations throughout soil profile were determined at 0, 10, 20, 40 and 90 days after application (DAA). Herbicides were subjected to two pluviometric regimens, natural field condition and modified conditions (plus natural rainfall 180 mm). Leaching indexes utilized were: Briggs's Rf, Hamaker's Rf, LEACH, LPI, GUS and LIX. Simazine reached 120 cm, diuron 90 cm, flumioxazin 30 cm soil depth respectively. Pendimethalin and oxyfluorfen were retained up to 5 cm. None of the herbicides leaching was affected by rainfall regimen. Only flumioxazin field dissipation was clearly affected by pluviometric condition. The best representation of the herbicide soil depth movement and leaching below 15 cm soil depth were: Hamaker's Rf < Briggs's Rf < GUS < LPI, < LEACH < LIX. Field results showed a good correlation between herbicides K(d) and their soil depth movement and mass leached below 15 cm soil depth. PMID:17849992

  9. Leaching heavy metals in municipal solid waste incinerator fly ash with chelator/biosurfactant mixed solution.

    Science.gov (United States)

    Xu, Ying; Chen, Yu

    2015-07-01

    The chelator [S,S]-ethylene diamine disuccinic acid, citric acid, and biosurfactant saponin are selected as leaching agents. In this study, the leaching effect of saponin mixed with either ethylene diamine disuccinic acid or citric acid on the levels of copper, zinc, lead, and cadmium in municipal solid waste incinerator fly ash is investigated. Results indicate that saponin separately mixed with ethylene diamine disuccinic acid and citric acid exhibits a synergistic solubilisation effect on copper, zinc, lead, and cadmium leaching from fly ash. However, saponin and ethylene diamine disuccinic acid mixed solution exhibits a synergistic solubilisation effect that is superior to that of a saponin and citric acid mixed solution. The extraction rate of heavy metal in fly ash leached with a saponin and chelator mixed solution is related to the pH of the leaching solution, and the optimal range of the pH is suggested to be approximately neutral. After leaching with a saponin and chelator mixed solution, copper, zinc, lead, and cadmium contents significantly decreased (p leaching concentrations of copper, zinc, lead, and cadmium in treated fly ash are in accordance with Standard for Pollution Control on the Security Landfill Site for Hazardous Wastes GB18598-2001. PMID:26185165

  10. LEACHING OF MALACHITE ORE IN AMMONIUM SULFATE SOLUTIONS AND PRODUCTION OF COPPER OXIDE

    Directory of Open Access Journals (Sweden)

    A. Ekmekyapar

    2015-03-01

    Full Text Available Abstract Malachite ore is one of the most important of oxidized copper ores. Copper production can be performed by using this ore. In this work, the leaching kinetics of malachite in ammonium sulfate solutions was investigated, and metallic copper was recovered by a cementation method from the resulting actual leach solution. Copper (II oxide was prepared by an isothermal oxidation method from the cement copper. In the leaching experiments, the effects of reaction temperature, particle size, and stirring speed on copper leaching from malachite ore were studied. In the cementation experiments, metallic zinc was used as the reductant metal to recover the copper from the solution. Thermal oxidation of cement copper was performed under isothermal conditions. It was found that the leaching rate increased with increasing stirring speed and temperature, and decreased with particle size. It was observed that the leaching reaction fit to diffusion through the product layer. The activation energy of the leaching process was determined to be 25.4 kJ/mol. It was determined that the copper content of the metallic product obtained by the cementation method increased up to 96%. It was found that copper oxide prepared from cement copper had a tenorite structure.

  11. ASSESSMENT OF INORGANIC POLLUTANTS LEACHING FROM WASTE IN THE PERCOLATION PROCESS

    Directory of Open Access Journals (Sweden)

    Kamila Mizerna

    2016-05-01

    Full Text Available The leaching of inorganic components from granular waste can be determined by up-flow column leaching test. The study allows researcher to assess the leaching behaviour of contaminants under specified percolation conditions (dynamic conditions. Dynamic tests simulate real conditions of the leaching of contaminants in the landfill aeration area. Percolation test also enables to perform observations on how the change of the liquid to solid (L/S ratio influences the obtained concentrations of particular components. Test conditions, including the flow rate of leachant, determine which components are quickly leached and which are released under the influence of contact with matrix. The paper presents the research results of heavy metals (Zn, Cd, Ni, Cu, Pb i Cr leaching from smelter waste using of column leaching test. The eluates with predetermined liquid to solid ratio (L/S = 0.1; 0.2; 0.5; 1.0; 2.0; 5.0; 10.0 were systematically collected. In eluates from each stage of the procedure the highest concentration of zinc and the lowest concentration of chromium were determined. The increase of heavy metals release from waste mass with increasing the L/S ratio was observed.

  12. An experimental study of pyrite bio-leaching as a way to control spontaneous combustion

    Institute of Scientific and Technical Information of China (English)

    Yin Shenghua; Wu Aixiang; Liu Jinzhi; Huang Mingqing; Wang Hongjiang

    2011-01-01

    Bio-leaching of pyrite by native strains of acidophilic bacteria was examined by laboratory scale tests.Three groups of batch trials in agitated flasks and three continuous column leaching tests were performed.The leaching ability and efficiency of native bacteria was greatly improved by adaptation of the bacteria to the test conditions.These cultivated bacteria were then used for the leaching process.The changes in solution pH,Eh,Fe2+ concentration,and sulfate ion concentration were monitored throughout the tests.A portion of the pyritic sulfur is transformed into soluble sulfate ion.The desulfurization ratio of 42.6% was obtained in a flask shaking test and a ratio of 39.4% was obtained during column leaching.A weight gain test was performed on leached and unleached samples by exposing the samples to humid air for several days.A smaller weight gain of the bio-leached samples indicates that removing sulfur from the sulphide ore helps reduce its oxidation rate and the potential for spontaneous combustion.

  13. Leaching characteristics of calcium-based compounds in MSWI Residues: From the viewpoint of clogging risk

    International Nuclear Information System (INIS)

    Highlights: • The leaching behavior of Ca-based compounds commonly in MSWI residues was studied. • pH is the crucial factor for calcium leaching process. • CaCO3 was the most sensitive to leaching temperature and Ca3(PO4)2 was the least. • Ca leaching of MSWIBA and SAPCR attributed to CaCO3 and Ca3(PO4)2 respectively. • Potential clogging ability of MSWI residues leachate in open air was calculated. - Abstract: Leachate collection system (LCS) clogging caused by calcium precipitation would be disadvantageous to landfill stability and operation. Meanwhile, calcium-based compounds are the main constituents in both municipal solid waste incineration bottom ash (MSWIBA) and stabilized air pollution control residues (SAPCR), which would increase the risk of LCS clogging once these calcium-rich residues were disposed in landfills. The leaching behaviors of calcium from the four compounds and municipal solid waste incineration (MSWI) residues were studied, and the influencing factors on leaching were discussed. The results showed that pH was the crucial factor in the calcium leaching process. CaCO3 and CaSiO3 began leaching when the leachate pH decreased to less than 7 and 10, respectively, while Ca3(PO4)2 leached at pH < 12. CaSO4 could hardly dissolve in the experimental conditions. Moreover, the sequence of the leaching rate for the different calcium-based compounds is as follows: CaSiO3 > Ca3(PO4)2 > CaCO3. The calcium leaching from the MSWIBA and SAPCR separately started from pH < 7 and pH < 12, resulting from CaCO3 and Ca3(PO4)2 leaching respectively, which was proven by the X-ray diffraction results. Based on the leaching characteristics of the different calcium compounds and the mineral phase of calcium in the incineration residues, simulated computation of their clogging potential was conducted, providing the theoretical basis for the risk assessment pertaining to LCS clogging in landfills

  14. Leaching characteristics of calcium-based compounds in MSWI Residues: From the viewpoint of clogging risk

    Energy Technology Data Exchange (ETDEWEB)

    Xia, Yi [State Key Laboratory of Pollution Control & Resource Reuse, Tongji University, Shanghai 200092 (China); Institute of Waste Treatment and Reclamation, Tongji University, Shanghai 200092 (China); Zhang, Hua, E-mail: zhanghua_tj@tongji.edu.cn [State Key Laboratory of Pollution Control & Resource Reuse, Tongji University, Shanghai 200092 (China); Phoungthong, Khamphe [State Key Laboratory of Pollution Control & Resource Reuse, Tongji University, Shanghai 200092 (China); Institute of Waste Treatment and Reclamation, Tongji University, Shanghai 200092 (China); Shi, Dong-Xiao; Shen, Wen-Hui [Changzhou Domestic Waste Treatment Center, Changzhou 213000 (China); Shao, Li-Ming [Institute of Waste Treatment and Reclamation, Tongji University, Shanghai 200092 (China); Center for the Technology Research and Training on Household Waste in Small Towns & Rural Area, Ministry of Housing and Urban–Rural Development of PR China (MOHURD), Shanghai 200092 (China); He, Pin-Jing, E-mail: solidwaste@tongji.edu.cn [Institute of Waste Treatment and Reclamation, Tongji University, Shanghai 200092 (China); Center for the Technology Research and Training on Household Waste in Small Towns & Rural Area, Ministry of Housing and Urban–Rural Development of PR China (MOHURD), Shanghai 200092 (China)

    2015-08-15

    Highlights: • The leaching behavior of Ca-based compounds commonly in MSWI residues was studied. • pH is the crucial factor for calcium leaching process. • CaCO{sub 3} was the most sensitive to leaching temperature and Ca{sub 3}(PO{sub 4}){sub 2} was the least. • Ca leaching of MSWIBA and SAPCR attributed to CaCO{sub 3} and Ca{sub 3}(PO{sub 4}){sub 2} respectively. • Potential clogging ability of MSWI residues leachate in open air was calculated. - Abstract: Leachate collection system (LCS) clogging caused by calcium precipitation would be disadvantageous to landfill stability and operation. Meanwhile, calcium-based compounds are the main constituents in both municipal solid waste incineration bottom ash (MSWIBA) and stabilized air pollution control residues (SAPCR), which would increase the risk of LCS clogging once these calcium-rich residues were disposed in landfills. The leaching behaviors of calcium from the four compounds and municipal solid waste incineration (MSWI) residues were studied, and the influencing factors on leaching were discussed. The results showed that pH was the crucial factor in the calcium leaching process. CaCO{sub 3} and CaSiO{sub 3} began leaching when the leachate pH decreased to less than 7 and 10, respectively, while Ca{sub 3}(PO{sub 4}){sub 2} leached at pH < 12. CaSO{sub 4} could hardly dissolve in the experimental conditions. Moreover, the sequence of the leaching rate for the different calcium-based compounds is as follows: CaSiO{sub 3} > Ca{sub 3}(PO{sub 4}){sub 2} > CaCO{sub 3}. The calcium leaching from the MSWIBA and SAPCR separately started from pH < 7 and pH < 12, resulting from CaCO{sub 3} and Ca{sub 3}(PO{sub 4}){sub 2} leaching respectively, which was proven by the X-ray diffraction results. Based on the leaching characteristics of the different calcium compounds and the mineral phase of calcium in the incineration residues, simulated computation of their clogging potential was conducted, providing the

  15. Intensified alkaline leaching pretreatment of refractory gold concentrates at common temperature and pressure

    Institute of Scientific and Technical Information of China (English)

    孟宇群; 吴敏杰; 宿少玲; 王隆保

    2003-01-01

    A new process for the hydrometallurgy of refractory gold concentrates was presented. The process comprises grinding-leaching, intensified alkaline leaching (IAL), cyanidation and adsorption. In a stirring-type pulverizing-leaching tower mill, the concentrate is ground to <35.6μm of 95.5 % while simultaneously leached by NaOH of 12kg/t, then carried out intensified alkaline leaching for 48h by NaOH of 108kg/t in enhanced agitation tanks with the pulp concentration of 40% solids at the environmental temperature of 9.5 ~ 13.5℃ and the environmental pressure of 105Pa. The oxidation rate of As is 94.9%, and 47.6% for S. The total consumption of NaOH is only 20% of that theoretically calculated under the conditions of full oxidation at the same oxidation rates of arsenic to arsenate and sulfur to sulfate. The gold leaching rate by NaCN in 24h is increased from 9.2% before pretreatment to 94.2%. The consumption of NaCN is 7.5kg/t, which is one times less than that before pretreatment. The extraction cost of gold is about 422Yuan/t.

  16. Identification of nitrate leaching loss indicators through regression methods based on a meta-analysis of lysimeter studies.

    Science.gov (United States)

    Boy-Roura, M; Cameron, K C; Di, H J

    2016-02-01

    This study presents a meta-analysis of 12 experiments that quantify nitrate-N leaching losses from grazed pasture systems in alluvial sedimentary soils in Canterbury (New Zealand). Mean measured nitrate-N leached (kg N/ha × 100 mm drainage) losses were 2.7 when no urine was applied, 8.4 at the urine rate of 300 kg N/ha, 9.8 at 500 kg N/ha, 24.5 at 700 kg N/ha and 51.4 at 1000 kg N/ha. Lismore soils presented significantly higher nitrate-N losses compared to Templeton soils. Moreover, a multiple linear regression (MLR) model was developed to determine the key factors that influence nitrate-N leaching and to predict nitrate-N leaching losses. The MLR analyses was calibrated and validated using 82 average values of nitrate-N leached and 48 explanatory variables representative of nitrogen inputs and outputs, transport, attenuation of nitrogen and farm management practices. The MLR model (R (2) = 0.81) showed that nitrate-N leaching losses were greater at higher urine application rates and when there was more drainage from rainfall and irrigation. On the other hand, nitrate leaching decreased when nitrification inhibitors (e.g. dicyandiamide (DCD)) were applied. Predicted nitrate-N leaching losses at the paddock scale were calculated using the MLR equation, and they varied largely depending on the urine application rate and urine patch coverage. PMID:26498804

  17. An experimental study of the dynamic features of shadow areas of caustics in response to loading/unloading fracture

    Institute of Scientific and Technical Information of China (English)

    许昭永; 杨润海; 赵晋明; 王赟赟; 熊秉衡; 王正荣; 梅世蓉

    2002-01-01

    Using a plexiglass sample and by means of real-time holographic interferometry and shadow optical method of caustics, the different features of dynamic variation in stress (strain) field, plastic area and nucleation zone (shadow area) when the sample fractures during loading (loading-fracture) and unloading (unloading-fracture) are studied visually. The results show that the strain nuclei (zones with dense fringes) appear first at the tips of prefabricated cracks at low stress, and then the shadow areas of caustics form with the increase of load. These nuclei and shadow areas can become larger, or smaller, when the process of loading, or unloading, goes on. When the stress is kept within a certain range, the shadow areas of caustics can become larger and smaller alternatively with repeated loading and unloading (cyclic loading). However, when loading and unloading at high stress, in particular when the macrofracture is about to appear, the variations of the shadow areas of caustics are irreversible and quite different. The shadow areas of caustics expand rapidly at an increasing speed when loading-fracture appears. In contrast, the shadow areas of caustics expand at a lower speed when unloading-fracture appears; besides, there is a circular shadow in front of the sharp-angle shaped area.

  18. The rate of caustic crossing microlensing events for Q2237+0305

    OpenAIRE

    Wyithe, J. S. B.; Webster, R. L.; Turner, E. L.

    1999-01-01

    Spectrophotometric observation of the gravitationally microlensed quasar Q2237+0305 during a High Magnification Event (HME) is potentially a very powerful tool for probing the structure of the quasars accretion disc on scales of less than 10^-8 arc seconds. How often we can expect to observe a HME is dependent on the lens system parameters of galactic transverse velocity, mean microlens mass and the size of the magnified continuum source. We have previously used published microlensed light-cu...

  19. Influence of thermal treatment on the caustic SCC of super austenitic stainless steel

    Energy Technology Data Exchange (ETDEWEB)

    Yoo, Y.R.; Park, Y.B.; Chung, T.J.; Kim, Y.S. [School of Advanced Materials Engineering, Andong National Univ. (Korea); Chang, H.Y. [Korea Power Engineering Co. (Korea); Park, Y.S. [Dept. of Metallurgical Engineering, Yonsei Univ. (Korea)

    2005-07-01

    In general, thermal treatment at 500 C {proportional_to} 900 C ranges depending upon alloy composition of stainless steels can sensitize the steels and promote the intergranular cracking, and their intergranular corrosion resistance is decreased. These behaviors seem to be related to the change of microstructures. So, heat treatment at that temperature range should be avoided in fabrication, especially welding of stainless steels. In this work, it is focused on the effect of thermal treatment on caustic stress corrosion cracking of super austenitic stainless steel - S32050 The low temperature thermal treatment increased greatly the resistance to caustic SCC than those of annealed specimen. This enhancement might be closely related to the reduction of residual stress and slightly large grain, but its resistance was not affected by the anodic polarization behavior. (orig.)

  20. Characterizing the Leaching Behavior of Coal Combustion Residues using the Leaching Environmental Assessment Framework (LEAF) to Inform Future Management Decisions

    Science.gov (United States)

    Abstract for presentation on Characterizing the Leaching Behavior of Coal Combustion Residues using the Leaching Environmental Assessment Framework (LEAF) to Inform Future Management Decisions. The abstract is attached.

  1. Leach and EP (extraction procedure) toxicity tests on grouted waste from Tank 106-AN

    Energy Technology Data Exchange (ETDEWEB)

    Serne, R.J.; Martin, W.J.; Lokken, R.O.; LeGore, V.L.; Lindenmeier, C.W.; Martin, P.F.C.

    1989-09-01

    Pacific Northwest Laboratory is conducting laboratory experiments to produce leach rate data for various waste species that will be contained in grout at Hanford. In the work reported here, grout made from Tank 106-AN liquid waste was used to produce empirical leach rate data for several radionuclides ({sup 60}Co, {sup 90}Sr, {99}Tc, {129}I, {137}Cs, and {sup 241}Am), stable major components (NO{sub 3}{sup {minus}}, NO{sub 2}{sup {minus}}, F, Cl, and Na), and trace metals (Cr, Mo, and Ni). Two types of tests were used to produce leach rate data: an intermittent replacement leach test (ANS 16.1 leach test) and a static leach test. Measured effective diffusivities of key species are as follows: 4 to 6 {times} 10{sup {minus}8} cm{sup 2}/sec for {sup 99}Tc, 3 to 7 {times} 10{sup {minus}8} cm{sup 2}/sec for {sup 129}I, 4 to 6 {times} 10{sup {minus}9} cm{sup 2}/sec for nitrate, and 6 to 7 {times} 10{sup {minus}9} cm{sup 2}/sec for nitrite. The leach indices of all species studied are above (more favorable than) the waste form criteria. The leach indices for {sup 99}Tc and {sup 129}I are 7.4 {plus minus} 1.2 and 7.6 {plus minus} 0.4, respectively, and are being further investigated in continuing studies of double-shell slurry feed grouts. An Extraction Procedure (EP) toxicity test was also conducted and the grouted water is considered nontoxic per this test protocol. 19 refs., 9 figs., 8 tabs.

  2. Caustic ingestion management: world society of emergency surgery preliminary survey of expert opinion

    OpenAIRE

    Kluger, Yoram; Ishay, Ofir Ben; Sartelli, Massimo; Katz, Amit; Ansaloni, Luca; Gomez, Carlos Augusto; Biffl, Walter; Catena, Fausto; Fraga, Gustavo P; Di Saverio, Salomone; Goran, Augustin; Ghnnam, Wagih; Kashuk, Jeffry; Leppäniemi, Ari; Marwah, Sanjay

    2015-01-01

    Caustic material ingestion injuries (CMI) are uncommon. Only 5,000 cases are reported in the United States each year and most acute care healthcare facilities admit only a few cases annually. Accordingly, no single institution can claim extensive experience, and management protocols are most probably based on either expert opinion or literature reports. In this study, we will attempt to review opinions and practices of representatives of the board members of the World Society of Emergency Sur...

  3. F-Area Acid/Caustic Basin groundwater monitoring report: Second quarter 1992

    International Nuclear Information System (INIS)

    During second quarter 1992, samples from the six FAC monitoring wells at the F-Area Acid/Caustic Basin were analyzed for herbicides, indicator parameters, major ions, pesticides, radionuclides, turbidity, volatile organic compounds, and other constituents. Monitoring results that exceeded the US Environmental Protection Agency's Primary Drinking Water Standards (PDWS) or the Savannah River Site flagging criteria or turbidity standards during the quarter are the focus of this report

  4. F-Area Acid/Caustic Basin groundwater monitoring report: Second quarter 1992

    Energy Technology Data Exchange (ETDEWEB)

    Thompson, C.Y.

    1992-09-01

    During second quarter 1992, samples from the six FAC monitoring wells at the F-Area Acid/Caustic Basin were analyzed for herbicides, indicator parameters, major ions, pesticides, radionuclides, turbidity, volatile organic compounds, and other constituents. Monitoring results that exceeded the US Environmental Protection Agency's Primary Drinking Water Standards (PDWS) or the Savannah River Site flagging criteria or turbidity standards during the quarter are the focus of this report.

  5. F-Area Acid/Caustic Basin groundwater monitoring report: Second quarter 1992

    Energy Technology Data Exchange (ETDEWEB)

    Thompson, C.Y.

    1992-09-01

    During second quarter 1992, samples from the six FAC monitoring wells at the F-Area Acid/Caustic Basin were analyzed for herbicides, indicator parameters, major ions, pesticides, radionuclides, turbidity, volatile organic compounds, and other constituents. Monitoring results that exceeded the US Environmental Protection Agency`s Primary Drinking Water Standards (PDWS) or the Savannah River Site flagging criteria or turbidity standards during the quarter are the focus of this report.

  6. Electrowinning of lead powder from chloride leach liquor

    Energy Technology Data Exchange (ETDEWEB)

    Owais, Ashour [Suez Canal Univ., Suez (Egypt). Metallurgical and Materials Engineering Dept.

    2012-11-15

    Electrowinning of lead powder from chloride leach liquor obtained from secondary lead slag leached in hydrochloric acid is the main aim of this work. The resulted lead chloride solution (leachate) containing 2.2 wt.-% Pb and 1.24 wt.-% HCl was electrowon in an electrolytic cell containing one graphite plate as inert anode and two lead sheets as starting permanent cathodes. Different electrolysis parameters such as current density, electrolyte temperature and electrolyte stirring rate were studied. As indicated by SEM, EDX and XRD analyses, fine and pure (100 % Pb) powders with a dispersed and needle-like shape were formed with cathodic current efficiency up to 67.9 % and electrical energy demand ranges from 0.809 to 4.998 kWh/kg Pb with productivity up to 2.63 g/Ah. (orig.)

  7. An approximation method for diffusion based leaching models

    International Nuclear Information System (INIS)

    In connection with the fixation of nuclear waste in a glassy matrix equations have been derived for leaching models based on a uniform concentration gradient approximation, and hence a uniform flux, therefore requiring the use of only Fick's first law. In this paper we improve on the uniform flux approximation, developing and justifying the approach. The resulting set of equations are solved to a satisfactory approximation for a matrix dissolving at a constant rate in a finite volume of leachant to give analytical expressions for the time dependence of the thickness of the leached layer, the diffusional and dissolutional contribution to the flux, and the leachant composition. Families of curves are presented which cover the full range of all the physical parameters for this system. The same procedure can be readily extended to more complex systems. (author)

  8. ALKALINE CARBONATE LEACHING PROCESS FOR URANIUM EXTRACTION

    Science.gov (United States)

    Thunaes, A.; Brown, E.A.; Rabbitts, A.T.

    1957-11-12

    A process for the leaching of uranium from high carbonate ores is presented. According to the process, the ore is leached at a temperature of about 200 deg C and a pressure of about 200 p.s.i.g. with a solution containing alkali carbonate, alkali permanganate, and bicarbonate ion, the bicarbonate ion functionlng to prevent premature formation of alkali hydroxide and consequent precipitation of a diuranate. After the leaching is complete, the uranium present is recovered by precipitation with NaOH.

  9. Column leaching from biomass combustion ashes

    DEFF Research Database (Denmark)

    Maresca, Alberto; Astrup, Thomas Fruergaard

    2015-01-01

    this study, a fly ash sample from an operating Danish power plant based on wood biomass was collected, chemically characterized and investigated for its leaching release of nutrients and heavy metals. A column leaching test was employed. The strongly alkaline pH of all the collected eluates suggested...... the potential suitability of the ash as a liming material. Although high contents of nutrients were detected, differences in their leaching release were found. Heavy metals were detected within typical literature contents for Nordic countries ashes....

  10. Leaching from municipal solid waste incineration residues

    Energy Technology Data Exchange (ETDEWEB)

    Hyks, J.

    2008-02-15

    Leaching of pollutants from Municipal Solid Waste Incineration (MSWI) residues has been investigated combining a range of laboratory leaching experiments with geochemical modeling. Special attention was paid to assessing the applicability of laboratory data for subsequent modeling with respect to presumed full-scale conditions; both sample pretreatment and actual influence of leaching conditions on the results of laboratory experiments were considered. It was shown that sample pretreatment may have large impact on leaching test data. In particular, a significant fraction of Pb was shown mobile during the washing of residues with water. In addition, drying of residues (i.e. slow oxidation) prior to leaching experiments increased the leaching of Cr significantly. Significant differences regarding the leaching behavior of individual elements with respect to (non)equilibrium conditions in column percolation experiments were observed in the study. As a result, three groups of elements were identified based on the predominant leaching control and the influence of (non)equilibrium on the results of the laboratory column experiments: I. Predominantly availability-controlled elements (e.g. Na, K, Cl) II. Solubility-controlled elements (e.g. Ca, S, Si, Al, Ba, and Zn) III. Complexation-controlled elements (e.g. Cu and Ni) With respect to the above groups it was suggested that results of laboratory column experiments can, with consideration, be used to estimate full-scale leaching of elements from Group I and II. However, in order to avoid large underestimations in the assessment of leaching from Group III, it is imperative to describe the time-dependent transport of dissolved organic carbon (DOC) in the tested system or to minimize the physical non-equilibrium during laboratory experiments (e.g. bigger column, slower flow velocity). Forward geochemical modeling was applied to simulate long-term release of elements from a MSWI air-pollution-control residue. Leaching of a

  11. Corrosion Study of Super Ferritic Stainless Steel UNS S44660 (26Cr-3Ni-3Mo) and Several Other Stainless Steel Grades (UNS S31603, S32101, and S32205) in Caustic Solution Containing Sodium Sulfide

    Science.gov (United States)

    Chasse, Kevin R.; Singh, Preet M.

    2013-11-01

    Electrochemical techniques, scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS) were used in this study to show how the corrosion mechanism of several commercial grades of stainless steel in hot caustic solution is strongly influenced by the presence of sodium sulfide. Experimental results from super ferritic stainless steel UNS S44660 (26Cr-3Ni-3Mo) were compared to austenitic stainless steel UNS S31603, lean duplex stainless steel (DSS) UNS S32101, and standard DSS UNS S32205 in caustic solution, with and without sodium sulfide, at 443 K (170 °C). Weight loss measurements indicated that corrosion rates of UNS44660 were much lower than the other grades of stainless steel in the presence of the sodium sulfide. Potentiodynamic polarization and linear polarization resistance measurements showed that the electrochemical behavior was altered by the adhesion of sulfur species, which reduced the polarization resistances and increased the anodic current densities. SEM and XPS results imply that the surface films that formed in caustic solution containing sodium sulfide were defective due to the adsorption of sulfide, which destabilized the passive film and led to the formation of insoluble metal sulfide compounds.

  12. An unconventional method for the recovery of caustic soda from spent Al-rich pickling solutions.

    Science.gov (United States)

    Aprea, Paolo; de Gennaro, Bruno; Colella, Carmine

    2011-07-01

    This work presents an unconventional procedure for the recovery of spent Al-rich caustic soda solutions from the pickling of dies for the production of aluminium extrusions. Caustic soda was regenerated at roughly 70%, by precipitating aluminate, after addition of a silica source, in the form of zeolite A, a microporous material that is widely used in many technological sectors. It was shown that the process is reliable and can be repeated for several cycles, provided the concentration of the caustic soda solution is suitably restored. The by-product obtained, zeolite A, proved to be a high-grade material with performance as a cation exchanger and physical sorbent that is certainly comparable to that reported in literature (e.g., cation exchange capacity equal to 5.14 meq g(-1) vs. 5.48 meq g(-1) and water vapour adsorption capacity of 26.5% vs. 27.6% at 16 torr and 298 K). The economics of the process, although not examined yet, would appear generally favourable, considering that zeolite A is a valuable by-product which widely covers the costs for the recovery of the spent solutions. There are, therefore, significant prospects for the use of zeolite A, particularly as a builder in detergent formulation. PMID:21458911

  13. The Efficacy of Mesenchymal Stem Cell Transplantation in Caustic Esophagus Injury: An Experimental Study

    Directory of Open Access Journals (Sweden)

    Murat Kantarcioglu

    2014-01-01

    Full Text Available Introduction. Ingestion of corrosive substances may lead to stricture formation in esophagus as a late complication. Full thickness injury seems to exterminate tissue stem cells of esophagus. Mesenchymal stem cells (MSCs can differentiate into specific cell lineages and have the capacity of homing in sites of injury. Aim and Methods. We aimed to investigate the efficacy of MSC transplantation, on prevention of esophageal damage and stricture formation after caustic esophagus injury in rats. 54 rats were allocated into four groups; 4 rats were sacrificed for MSC production. Group 1, untreated controls (n: 10. Group 2, membrane labeled MSCs-treated rats (n: 20. Group 3, biodistribution of fluorodeoxyglucose labeled MSCs via positron emission tomography (PET imaging (n: 10. Group 4, sham operated (n: 10. Standard caustic esophageal burns were created and MSCs were transplanted 24 hours after. All rats were sacrificed at the 21st days. Results. PET scan images revealed the homing behavior of MSCs to the injury site. The histopathology damage score was not significantly different from controls. However, we demonstrated Dil labeled epithelial and muscle cells which were originating from transplanted MSCs. Conclusion. MSC transplantation after caustic esophageal injury may be a helpful treatment modality; however, probably repeated infusions are needed.

  14. 热酸浸出锌浸渣中镓锗的研究%Extracting Gallium and Germanium from Zinc-leaching Residues by Hot-acid Leaching Process

    Institute of Scientific and Technical Information of China (English)

    马喜红; 覃文庆; 吴雪兰; 任浏祎

    2012-01-01

    研究了锌浸渣热酸浸出过程的工艺条件,分析了浸出热力学和动力学机理,并用于指导回收稀有金属镓和锗.实验结果表明,锌浸渣中镓和锗浸出的最佳工艺条件为:硫酸初始质量浓度为188 g/L,反应温度为95℃,反应时间为3h,液固比为5∶1,搅拌速度为300 r/min,该条件下多组综合实验的酸浸出液中Ga和Ge的浸出率均高于86%和62%.锌浸渣中金属镓锗的浸出过程在动力学上属于“未反应核减缩”模型,浸出过程主要受反应温度、始酸浓度、反应时间的影响,反应由界面化学反应控制.%Extraction of gallium and germanium from zinc leaching residue was carried out by hot-acid leaching. The effects of leaching agent ( sulfuric acid) , leaching temperature, leaching time, L/S ratio and agitation speed on the leaching rate of Ga and Ge were examined, while the thermodynamics and dynamic mechanism for the leaching were, also analyzed. Results showed that the optimal leaching conditions were as follows: the initial mass concentration of sulfuric acid was 188 g/L, leaching temperature was 95 ℃ , leaching time was 3 h, L/S ratio was 5:1, and agitation speed was 300 r/min. Under these conditions, the leaching rates of Ga and Ge in acid leaching solution from multi-group comprehensive tests were averagely above 86% and 62% , respectively. Furthermore, the leaching process of Ga and Ge follows the kinetic law of "shrinking of unreacted core" , mainly influenced by leaching temperature, concentration of sulfuric acid and leaching time, also being controlled by interface chemical reaction.

  15. Uranium recovery from acid leach liquors: Ix or Sx?

    International Nuclear Information System (INIS)

    Various technologies for uranium recovery from sulphuric acid leach solutions were compared. Although the main consideration was the economics (Capex, recovery and Opex) of the various technologies and associated unit operations, other factors, such as flexibility, reliability, ease of operation, fire risk, stability with regards to feed flow variations, and feed solids content, would also need to be considered in the overall analysis. The design basis used for the comparison was a production rate or 200 kg/h U3O8 over a solution concentration range of 40 to 1500 mg/L U3O8. The technologies to be compared included Resin-in-pulp (RIP), Fixed-bed Ion Exchange (FBIX), Continuous Countercurrent Ion Exchange (CCIX, e.g. NIMCIX), and Solvent Extraction (Sx) using Bateman Pulsed Columns (BPC) and Bateman Settlers. Countercurrent Decantation (CCD) and clarification would be required for the Sx and FBIX technologies. The preliminary economic evaluation indicated that a flowsheet, comprising RIP for bulk uranium extraction and upgrade, followed by Sx, employing the BPC for purification of the RIP eluate stream, was the most economic option at leach liquor concentrations below 900 mg/L. Above 900 mg/L the economic evaluation suggested that CCDs followed by Sx in the BPC was the most economical processing option. For applications where the ore is abrasive and not amenable to RIP, due to the rate of resin consumption, Paste Thickeners to remove the bulk of the solids, followed by RIP, was found to be the most economic processing option at leach liquor concentrations below 200 mg/L. However, for leach liquor concentrations above 200 mg/L, a CCD-circuit followed by Sx using BPC was again the most economic favourable route

  16. Development of mathematic model for coffee decaffeination with leaching method

    Directory of Open Access Journals (Sweden)

    Sukrisno Widyotomo

    2011-08-01

    Full Text Available A simple mathematic model for caffeine kinetic description during the extraction process (leaching of coffee bean was developed. A non­steady diffusion equation coupled with a macroscopic mass transfer equation for solvent was developed and them solved analytically. The kinetic of caffeine extraction from coffee bean is depend on initial caffeine content, final caffeine content, caffeine content at certain time, mass­transfer coefficient, solvent volume, surface area of coffee beans, process time, radius of coffee bean, leaching rate of caffeine, caffeine diffusivity and a are constan, solvent concentration, activation energy, temperature absolute and gas constant. Caffeine internal mass diffusivity was estimated by fitting the model to an experiment using acetic acid and liquid waste of cocoa beans fermentation. The prediction equation for leaching rate of caffeine in coffee beans has been found. It was found that Dk (m2/sec=1.345x10­7—4.1638x10­7, and kL (m/sec=2.445x10­5—5.551x10­5 by acetic acid as solvent depended on temperature and solvent concentration. The prediction equation for length of time to reduce initial caffeine content to certain concentration in coffee beans has been developed, Caffeine diffusivity (Dk and mass­transfer coefficient (kL was found respectively 1.591x 10­7—2.122x10­7 m2/sec and 4.897x10­5—6.529x10­5 m/sec using liquid waste of cocoa bean fermentation as solvent which depend on temperature and solvent concentration. Key words: Coffee, caffeine, decaffeination, leaching, mathematic model.

  17. Cyclic stress effect on stress corrosion cracking of duplex stainless steel in chloride and caustic solutions

    Science.gov (United States)

    Yang, Di

    Duplex stainless steel (DSS) is a dual-phase material with approximately equal volume amount of austenite and ferrite. It has both great mechanical properties (good ductility and high tensile/fatigue strength) and excellent corrosion resistance due to the mixture of the two phases. Cyclic loadings with high stress level and low frequency are experienced by many structures. However, the existing study on corrosion fatigue (CF) study of various metallic materials has mainly concentrated on relatively high frequency range. No systematic study has been done to understand the ultra-low frequency (˜10-5 Hz) cyclic loading effect on stress corrosion cracking (SCC) of DSSs. In this study, the ultra-low frequency cyclic loading effect on SCC of DSS 2205 was studied in acidified sodium chloride and caustic white liquor (WL) solutions. The research work focused on the environmental effect on SCC of DSS 2205, the cyclic stress effect on strain accumulation behavior of DSS 2205, and the combined environmental and cyclic stress effect on the stress corrosion crack initiation of DSS 2205 in the above environments. Potentiodynamic polarization tests were performed to investigate the electrochemical behavior of DSS 2205 in acidic NaCl solution. Series of slow strain rate tests (SSRTs) at different applied potential values were conducted to reveal the optimum applied potential value for SCC to happen. Room temperature static and cyclic creep tests were performed in air to illustrate the strain accumulation effect of cyclic stresses. Test results showed that cyclic loading could enhance strain accumulation in DSS 2205 compared to static loading. Moreover, the strain accumulation behavior of DSS 2205 was found to be controlled by the two phases of DSS 2205 with different crystal structures. The B.C.C. ferrite phase enhanced strain accumulation due to extensive cross-slips of the dislocations, whereas the F.C.C. austenite phase resisted strain accumulation due to cyclic strain

  18. High-Zinc Recovery from Residues by Sulfate Roasting and Water Leaching

    Science.gov (United States)

    Hu, Ming; Peng, Bing; Chai, Li-yuan; Li, Yan-chun; Peng, Ning; Yuan, Ying-zhen; Chen, Dong

    2015-09-01

    An integrated process for the recovery of zinc that is generated from zinc hydrometallurgy in residues was developed. A mixture of residue and ferric sulfate was first roasted to transform the various forms of zinc in the residue, such as ferrite, oxide, sulfide, and silicate, into zinc sulfate. Next, water leaching was conducted to extract the zinc while the iron remained in the residue as ferric oxide. The effects of the roasting and leaching parameters on zinc recovery were investigated. A maximum zinc recovery rate of 90.9% was achieved for a mixture with a ferric sulfate/residue weight ratio of 0.05 when roasting at 640°C for 30 min before leaching with water at room temperature for 20 min using a liquid/solid ratio of 10. Only 0.13% of the iron was dissolved in the water. Thus, the leaching liquor could be directly returned for zinc smelting.

  19. Characterization, Leaching, and Filtration Testing for Bismuth Phosphate Sludge (Group 1) and Bismuth Phosphate Saltcake (Group 2) Actual Waste Sample Composites

    Energy Technology Data Exchange (ETDEWEB)

    Lumetta, Gregg J.; Buck, Edgar C.; Daniel, Richard C.; Draper, Kathryn; Edwards, Matthew K.; Fiskum, Sandra K.; Hallen, Richard T.; Jagoda, Lynette K.; Jenson, Evan D.; Kozelisky, Anne E.; MacFarlan, Paul J.; Peterson, Reid A.; Shimskey, Rick W.; Sinkov, Sergey I.; Snow, Lanee A.

    2009-02-19

    A testing program evaluating actual tank waste was developed in response to Task 4 from the M-12 External Flowsheet Review Team (EFRT) issue response plan.() The test program was subdivided into logical increments. The bulk water-insoluble solid wastes that are anticipated to be delivered to the Waste Treatment and Immobilization Plant (WTP) were identified according to type such that the actual waste testing could be targeted to the relevant categories. Eight broad waste groupings were defined. Samples available from the 222S archive were identified and obtained for testing. The actual waste-testing program included homogenizing the samples by group, characterizing the solids and aqueous phases, and performing parametric leaching tests. Two of the eight defined groups—bismuth phosphate sludge (Group 1) and bismuth phosphate saltcake (Group 2)—are the subjects of this report. The Group 1 waste was anticipated to be high in phosphorus and was implicitly assumed to be present as BiPO4 (however, results presented here indicate that the phosphate in Group 1 is actually present as amorphous iron(III) phosphate). The Group 2 waste was also anticipated to be high in phosphorus, but because of the relatively low bismuth content and higher aluminum content, it was anticipated that the Group 2 waste would contain a mixture of gibbsite, sodium phosphate, and aluminum phosphate. Thus, the focus of the Group 1 testing was on determining the behavior of P removal during caustic leaching, and the focus of the Group 2 testing was on the removal of both P and Al. The waste-type definition, archived sample conditions, homogenization activities, characterization (physical, chemical, radioisotope, and crystal habit), and caustic leaching behavior as functions of time, temperature, and hydroxide concentration are discussed in this report. Testing was conducted according to TP-RPP-WTP-467.

  20. Watchdog-LEACH: A new method based on LEACH protocol to Secure Clustered Wireless Sensor Networks

    Directory of Open Access Journals (Sweden)

    Mohammad Reza Rohbanian

    2013-07-01

    Full Text Available Wireless sensor network comprises of small sensor nodes with limited resources. Clustered networks have been proposed in many researches to reduce the power consumption in sensor networks. LEACH is one of the most interested techniques that offer an efficient way to minimize the power consumption in sensor networks. However, due to the characteristics of restricted resources and operation in a hostile environment, WSNs are subjected to numerous threats and are vulnerable to attacks. This research proposes a solution that can be applied on LEACH to increase the level of security. In Watchdog-LEACH, some nodes are considered as watchdogs and some changes are applied on LEACH protocol for intrusion detection. Watchdog-LEACH is able to protect against a wide range of attacks and it provides security, energy efficiency and memory efficiency. The result of simulation shows that in comparison to LEACH, the energy overhead is about 2% so this method is practical and can be applied to WSNs.

  1. Effect of Tetrachloroethylene on Sphalerite Leaching

    Institute of Scientific and Technical Information of China (English)

    王兴尧; 彭鹏; 谢慧琴; 卢立柱

    2004-01-01

    The effects of tetrachloroethylene (C2C14) on sphalerite leaching in FeCl3-HCl wereinvestigated in view of simultaneous mass transfer and reaction, and the leaching models with andwithout organic solvent C2Cl4 were derived. The leaching experiments and the SEM results show thatC2C14 is an effective organic solvent for sphalerite leaching in FeC13-HC1 system to be accelerated andfor the sulfur to be separated. Adding C2C14 in the FeCl3-HC1 medium will turn the kinetic modelcontrolled by sulfur layer diffusion with process activation energy of 67.9 kJ/mol into mixed diffusionwith the energy reduced to 55.1 kJ/mol when 20 ml of C2C14 was added.

  2. Alternative leaching processes for uranium ores

    International Nuclear Information System (INIS)

    Laboratory studies have been carried out to compare the extraction of uranium from Australian ores by conventional leaching in sulphuric acid with that obtained using hydrochloric acid and acidified ferric sulphate solutions. Leaching with hydrochloric acid achieved higher extractions of radium-226 but the extraction of uranium was reduced considerably. The use of acidified ferric sulphate solution reduced acid consumption by 20-40% without any detrimental effect on uranium extraction. The ferric ion, which is reduced during leaching, can be reoxidized and recycled after the addition of acid makeup. Hydrogen peroxide was found to be an effective oxidant in conventional sulphuric acid leaching. It is more expensive than alternative oxidants, but it is non-polluting, lesser quantities are required and acid consumption is reduced

  3. Phosphorus Leaching in an Acid Tropical Soil “Recapitalized” with Phosphate Rock and Triple Superphosphate

    Directory of Open Access Journals (Sweden)

    E. Gikonyo

    2010-01-01

    Full Text Available With high rates of phosphorus applied to increase “capital P” as a stock for plant uptake over several years, the question of P leaching is inevitable. We conducted an intact soil column experiment in the field to evaluate P leached from soils treated with triple superphosphate (TSP and Gafsa phosphate rock (GPR at 300, 600, and 900 kg P ha-1 with and without integration of cattle manure. The lysimeters, made from PVC tubes of 30-cm length, were inserted into the soil up to the 25-cm depth. The tubes were fitted with a resin bag containing a mixture of cation and anion exchange resin (50:50 at the lower end of the tube inserted into the soil. The tubes, arranged in a completely randomized design, were sampled randomly at 10-week intervals for 12 months. Phosphorus extractable from the top- and subsoil at the end of experiment and leached P were determined. More P was leached out from TSP (threefold compared to GPR, and the amount of P leached increased with increasing rates of P fertilizer applied. Application of manure intensified the amounts of P leached from TSP, particularly at the 6-month sampling time. There was hardly any substantial P leached from the soil treated with GPR. Thus, for effective and efficient long-term P fertilizer management strategies, choosing the right P fertilizer source and monitoring P losses through leaching has to be done for enhanced fertilizer use efficiency and thus reducing P pollution of ground waters.

  4. YACON INULIN LEACHING DURING HOT WATER BLANCHING

    OpenAIRE

    Caroline Fenner Scher; Adriano Brandelli; Caciano Zapata Noreña

    2015-01-01

    ABSTRACTYacon roots contain inulin, which has prebiotic properties and it may be used as sucrose or fat substitutes. However, inulin is very soluble in water. The loss of this important nutrient during blanching is caused mainly by diffusion or leaching, which might be diminished if blanching temperature - time conditions are correctly employed. The aim of this study was to determine the leaching of the sugars inulin, glucose and fructose, present in yacon roots, during hot water blanching un...

  5. Bacterial oxidation activity in heap leaching

    Institute of Scientific and Technical Information of China (English)

    柳建设; 夏海波; 王兆慧; 胡岳华

    2004-01-01

    Bioleaching of sulfide minerals by bacteria, mainly Thiobacillus ferrooxidans (T. f. ) and Thiobacillus thiooxidans, plays an important role in hydrometallurgy because of its economic and environmental attractions. The surveys of production process and the bacterial oxidation activity in the heap bioleaching were investigated. The results show that pH value is high, bacteria biomass and ferric concentration are low, generation time (above 7.13 h)is long in leachate, and less bacteria are adsorbed on the ores. The bacteria in the leachate exposing on the surface and connecting with mineral, have much faster oxidation rate of Fe( Ⅱ ) and shorter generation time, compared with those which are in the reservoir for a long time. There is diversity for oxidation activity of Fe( Ⅱ ), while there is no diversity for oxidation of sulfur. So it is advisable to add sulfuric acid to degrade pH value to 2.0, add nutrients and shorten recycling time of leachate, so as to enhance bacteria concentration of leachate and the leaching efficiency.

  6. Mesophilic leaching of copper sulphide sludge

    Directory of Open Access Journals (Sweden)

    VLADIMIR B. CVETKOVSKI

    2009-02-01

    Full Text Available Copper was precipitated using a sodium sulphide solution as the precipitation agent from an acid solution containing 17 g/l copper and 350 g/l sulphuric acid. The particle size of nearly 1 µm in the sulphide sludge sample was detected by optical microscopy. Based on chemical and X-ray diffraction analyses, covellite was detected as the major sulphide mineral. The batch bioleach amenability test was performed at 32 °C on the Tk31 mine mesophilic mixed culture using a residence time of 28 days. The dissolution of copper sulphide by direct catalytic leaching of the sulphides with bacteria attached to the particles was found to be worthy, although a small quantity of ferrous ions had to be added to raise the activity of the bacteria and the redox potential of the culture medium. Throughout the 22-day period of the bioleach test, copper recovery based on residue analysis indicated a copper extraction of 95 %, with copper concentration in the bioleach solution of 15 g/l. The slope of the straight line tangential to the exponential part of the extraction curve gave a copper solubilisation rate of 1.1 g/l per day. This suggests that a copper extraction of 95 % for the period of bioleach test of 13.6 days may be attained in a three-stage bioreactor system.

  7. Intoxicación por cáusticos Poisoning by caustic substances

    Directory of Open Access Journals (Sweden)

    E. Mencías

    2003-01-01

    Full Text Available A la hora de valorar a un paciente que ha ingerido un cáustico existen guías o protocolos de tratamiento discordantes. Diversas ideas o tendencias hablan a favor de diluir, neutralizar, provocar el vómito, realizar lavado gástrico, etc., dependiendo del medio en que se haga la encuesta: domicilio, centro de salud, servicio de urgencias u hospital. Lo mismo sucede con el tipo de diluyente o neutralizante a usar, cómo y cuándo iniciar pauta de tratamiento con corticoides y/o antibióticos y antisecretores, y eso si es que hay que hacerlo. Se ha realizado una revisión bibliográfica exhaustiva, un trabajo experimental y el estudio de diversas guías o protocolos de diagnóstico y tratamiento que se siguen en diversos hospitales españoles. A escala experimental se evidencia que existen marcadores histopatológicos que desaconsejan la utilización de sustancias diluyentes tras la ingestión de álcalis cáusticos. Salvo en los casos de ingesta de sustancias cáusticas sólidas -cristalinas o granulosas- se contraindica, de forma absoluta, la dilución. Los corticoides no son eficaces cuando se ingiere un ácido cáustico; su uso es más que cuestionable tras la ingesta de álcalis cáusticos. El diagnóstico y calidad de tratamiento se apoya en la endoscopia. No existe un criterio único que defina en qué momento (tiempo post-ingesta es más conveniente llevarla a cabo, aunque el periodo comprendido entre las primeras 6-12 horas es el más adecuado. Se presenta un protocolo independiente de diagnóstico y tratamiento -en forma de algoritmos- que debe seguirse tras la ingesta de ácidos cáusticos o álcalis cáusticos.There are discordant guides and protocols when it comes to treating a patient who has ingested a caustic substance. Different ideas or tendencies speak in favour of dilution, neutralization, provoking vomiting, carrying out stomach washes, etc., depending on the milieu where the problem arises: at home, at the health centre

  8. Treatment of cadmium dust with two-stage leaching process

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The treatment of cadmium dust with a two-stage leaching process was investigated to replace the existing sulphation roast-leaching processes. The process parameters in the first stage leaching were basically similar to the neutralleaching in zinc hydrometallurgy. The effects of process parameters in the second stage leaching on the extraction of zincand cadmium were mainly studied. The experimental results indicated that zinc and cadmium could be efficiently recoveredfrom the cadmium dust by two-stage leaching process. The extraction percentages of zinc and cadmium in two stage leach-ing reached 95% and 88% respectively under the optimum conditions. The total extraction percentage of Zn and Cdreached 94%.

  9. Heat transfer law in leaching dump

    Institute of Scientific and Technical Information of China (English)

    WU Ai-xiang; WANG Hong-jiang; XI Yong; YANG Bao-hua; LI Jian-feng; YIN Sheng-hua; ZHA Ke-bing

    2005-01-01

    Based on the law of temperature changes in the leaching dump and the forming process of heat flux, the basic balance equation of heat flow in dump was established, the dissipated heat flow from dump to the atmosphere was analyzed to estimate the surface temperature of the ore particle in dump and discover the law of forced heat convection of heat flow transfer in dump. And the lixiviate flow formula taking a certain heat flow out of dump was deduced by using the inversion method. Through theoretic analysis, combining Dexing copper mine heap leaching production practice, the results show that the heat flow of chalcopyrite leaching emitted is not so great, but the heat flow of pyrite leaching and sulphur oxidation produced take up a higher proportion of total heat flow; the dissipated heat flow takes up a lower proportion, and most of heat flow is absorbed by itself, thus the inside temperature rises gradually; and the saturation flow form for leaching is adopted, which makes the lixiviate seepage in the transitional flow or even in the turbulent flow, so as to accelerate the heat flow diffusing and keep the leaching dump temperature suitable for bacteria living.

  10. Zinc Leaching from Tire Crumb Rubber

    Science.gov (United States)

    Rhodes, E. P.; Ren, J.; Mays, D. C.

    2010-12-01

    Recent estimates indicate that more than 2 billion scrap tires are currently stockpiled in the United States and approximately 280 million more tires are added annually. Various engineering applications utilize recycled tires in the form of shredded tire crumb rubber. However, the use of tire crumb rubber may have negative environmental impacts, especially when the rubber comes into contact with water. A review of the literature indicates that leaching of zinc from tire crumb rubber is the most significant water quality concern associated with using this material. Zinc is generally used in tire manufacturing, representing approximately 1.3% of the final product by mass. This study will report results from the U.S. Environmental Protection Agency’s (EPA’s) Synthetic Precipitation Leaching Procedure, batch leaching tests, and column leaching tests performed to quantify the process by which zinc leaches from tire crumb rubber into water. Results are interpreted with a first-order kinetic attachment/detachment model, implemented with the U.S. Agricultural Research Service software HYDRUS-1D, in order to determine the circumstances when zinc leaching from tire crumb rubber would be expected to comply with the applicable discharge limits. One potential application for recycled tires is replacing sand with tire crumb rubber in granular media filters used for stormwater pollution control. For this to be a viable application, the total zinc in the stormwater discharge must be below the EPA’s benchmark value of 0.117 mg/L.

  11. Leaching of nano-ZnO in municipal solid waste.

    Science.gov (United States)

    Sakallioglu, T; Bakirdoven, M; Temizel, I; Demirel, B; Copty, N K; Onay, T T; Uyguner Demirel, C S; Karanfil, T

    2016-11-01

    Despite widespread use of engineered nanomaterials (ENMs) in commercial products and their potential disposal in landfills, the fate of ENMs in solid waste environments are still not well understood. In this study, the leaching behavior of nano ZnO -one of the most used ENMs- in fresh municipal solid waste (MSW) was investigated. Batch reactors containing municipal solid waste samples were spiked with three different types of nano ZnO having different surface stabilization. The leaching of ZnO was examined under acidic, basic and elevated ionic strength (IS) conditions. The results of the 3-day batch tests showed that the percent of the added nano-ZnO mass retained within the solid waste matrix ranged between 80% and 93% on average for the three types of nano-ZnO tested. The pH and IS conditions did not significantly influence the leaching behavior of ZnO. To further analyze the behavior of ZnO in the MSW matrix, a kinetic particle deposition/detachment model was developed. The model was able to reproduce the main trends of the batch experiments. Reaction rate constants for the batch tests ranged from 0.01 to 0.4 1/hr, reflecting the rapid deposition of nano-ZnO within the MSW matrix. PMID:27318728

  12. Suppressing Heavy Metal Leaching through Ball Milling of Fly Ash

    Directory of Open Access Journals (Sweden)

    Zhiliang Chen

    2016-07-01

    Full Text Available Ball milling is investigated as a method of reducing the leaching concentration (often termed stablilization of heavy metals in municipal solid waste incineration (MSWI fly ash. Three heavy metals (Cu, Cr, Pb loose much of their solubility in leachate by treating fly ash in a planetary ball mill, in which collisions between balls and fly ash drive various physical processes, as well as chemical reactions. The efficiency of stabilization is evaluated by analysing heavy metals in the leachable fraction from treated fly ash. Ball milling reduces the leaching concentration of Cu, Cr, and Pb, and water washing effectively promotes stabilization efficiency by removing soluble salts. Size distribution and morphology of particles were analysed by laser particle diameter analysis and scanning electron microscopy. X-ray diffraction analysis reveals significant reduction of the crystallinity of fly ash by milling. Fly ash particles can be activated through this ball milling, leading to a significant decrease in particle size, a rise in its BET-surface, and turning basic crystals therein into amorphous structures. The dissolution rate of acid buffering materials present in activated particles is enhanced, resulting in a rising pH value of the leachate, reducing the leaching out of some heavy metals.

  13. Electro chemical studies on stress corrosion cracking of Incoloy-800 in caustic solution, part I: As received samples

    Directory of Open Access Journals (Sweden)

    Dinu Alice

    2005-01-01

    Full Text Available Many non-volatile impurities accidentally introduced into the steam generator tend to Concentrate on its surface in restricted flow areas. In this way these impurities can lead to stress corrosion cracking (SCC on stressed tubes of the steam generator. Such impurities can be strong alkaline or acid solutions. To evaluate the effect of alkaline concentrated environments on SCC of steam generator tubes, the tests were con ducted on stressed samples of Incoloy-800 in 10% NaOH solution. To accelerate the SCC process, stressed specimens were anodically polarised in a caustic solution in an electro chemical cell. The method of stressing of Incoloy-800 tubes used in our experiments was the C-ring. Using the cathodic zone of the potentiodynamic curves it was possible to calculate the most important electrochemical parameters: the corrosion current, the corrosion rate, and the polarization resistance. We found that the value of the corrosion potential to initiate the SCC microcracks was -100 mV. The tested samples were examined using the metallographic method. The main experimental results showed that the in crease of the stress state promoted the in crease of the SCC susceptibility of Incoloy-800 samples tested under the same conditions, and that the length of the SCC-type microcracks in creased with the growth of the stress value.

  14. Electrochemical studies on stress corrosion cracking of Incoloy-800 in caustic solution Part I: As received samples

    International Nuclear Information System (INIS)

    Many non-volatile impurities accidentally introduced into the steam generator tend to concentrate on its surface in restricted flow areas. In this way these impurities can lead to stress corrosion cracking (SCC) on stressed tubes of the steam generator. Such impurities can be strong alkaline or acid solutions. To evaluate the effect of alkaline concentrated environments on SCC of steam generator tubes, the tests were conducted on stressed samples of Incoloy-800 in 10% NaOH solution. To accelerate the SCC process, stressed specimens were anodically polarised in a caustic solution in an electrochemical cell. The method of stressing of Incoloy-800 tubes used in our experiments was the C-ring. Using the cathodic zone of the potentiodynamic curves it was possible to calculate the most important electrochemical parameters: the corrosion current, the corrosion rate, and the polarisation resistance. We found that the value of the corrosion potential to initiate the SCC microcracks was -100 mV. The tested samples were examined using the metallographic method. The main experimental results showed that the increase of the stress state promoted the increase of the SCC susceptibility of Incoloy-800 samples tested under the same conditions, and that the length of the SCC-type microcracks increased with the growth of the stress value. (author)

  15. Prediction of yttrium, lanthanum, cerium, and neodymium leaching recovery from apatite concentrate using artificial neural networks

    Institute of Scientific and Technical Information of China (English)

    E. Jorjani; A.H. Bagherieh; Sh. Mesroghli; S. Chehreh Chelgani

    2008-01-01

    The assay and recovery of rare earth elements (REEs) in the leaching process is being determined using expensive analytical methods: inductively coupled plasma atomic emission spectroscopy (ICP-AES) and inductively coupled plasma mass spectroscopy (ICP-MS). A neural network model to predict the effects of operational variables on the lanthanum, cerium, yttrium, and neodymium recovery in the leaching of apatite concentrate is presented in this article. The effects of leaching time (10 to 40 min),pulp densities (30% to 50%), acid concentrations (20% to 60%), and agitation rates (100 to 200 r/min), were investigated and optimized on the recovery of REEs in the laboratory at a leaching temperature of 60οC. The obtained data in the laboratory optimization process were used for training and testing the neural network. The feed-forward artificial neural network with a 4-5-5-1 arrangement was capable of estimating the leaching recovery of REEs. The neural network predicted values were in good agreement with the experimental results. The correlations of R=1 in training stages, and R=0.971, 0.952, 0.985, and 0.98 in testing stages were a result of Ce, Nd, La, and Y recovery prediction respectively, and these values were usually acceptable. It was shown that the proposed neural network model accurately reproduced all the effects of the operation variables, and could be used in the simulation of a leaching plant for REEs.

  16. Kinetics and mechanism of sphalerite leaching by sodium nitrate in sulphuric acid solution

    Directory of Open Access Journals (Sweden)

    Sokić M.

    2012-01-01

    Full Text Available Interest for application of hydrometallurgical processes in a processing of complex sulphide ores and concentrates has increased in recent years. Their application provides better metal recoveries and reduced emission of gaseous and toxic ageneses in the environment. The kinetics and mechanism of sphalerite leaching from complex sulphide concentrate with sulphuric acid and sodium nitrate solution at standard conditions was presented in this paper. The influences of temperature and time on the leaching degree of zinc were investigated and kinetic analysis of the process was accomplished. With temperature increasing from 60 to 90°C, the zinc leaching increased from 25.23% to 71.66% after 2 hours, i.e. from 59.40% to 99.83% after 4 hours. The selected kinetic model indicated that the diffusion through the product layer was the rate-controlling step during the sphalerite leaching. The activation energy was determined to be 55 kJ/mol in the temperature range 60-90°C. XRD, light microscopy and SEM/EDX analyses of the complex concentrate and leach residue confirmed formation of elemental sulphur and diffusion-controlled leaching mechanism.

  17. Near-surface leaching studies of Pb-implanted Savannah River waste glass

    Energy Technology Data Exchange (ETDEWEB)

    Arnold, G.W.; Northrup, C.J.M.; Bibler, N.E.

    1982-01-01

    The present experiments with Savannah River Plant simulated nuclear waste glass implanted with Pb ions, used Rutherford backscattering spectrometry and elastic recoil detection to follow in detail the changes in composition which occur in the near-surface region upon leaching in deionized water at 90/sup 0/C. Analyses of the leach solutions were made in an attempt to correlate the actual leach rates with the observed near-surface compositional changes. These experiments show that radiation damage can cause changes in the composition of the near-surface of the leached glass. We also find that a critical fluence is reached where abrupt changes of the surface elemental composition occur as a result of leaching. This fluence is near the value observed by both Dran, et al. and Primak. Solution analyses were not made for all the leaching experiments. However, those analyses which were made indicate that the amount of material actually leaving the glass is not significantly increased as a result of the radiation damage.

  18. Leaching of seven pesticides currently used in cotton crop in Mato Grosso State-Brazil.

    Science.gov (United States)

    Martins, Eucarlos L; Weber, Oscarlina L S; Dores, Eliana F G C; Spadotto, Cláudio A

    2007-11-01

    This study aimed to evaluate the leaching of pesticides and the applicability of the Attenuation Factor (AF) Model to predict their leaching. The leaching of carbofuran, carbendazim, diuron, metolachlor, alpha and beta endosulfan and chlorpyrifos was studied in an Oxisol using a field experiment lysimeter located in Dom Aquino-Mato Grosso. The samples of percolated water were collected by rain event and analyzed. Chemical and physical soil attributes were determined before pesticide application to the plots. The results showed that carbofuran was the pesticide that presented a higher leaching rate in the studied soil, so was the one representing the highest contamination potential. From the total carbofuran applied in the soil surface, around 6% leached below 50 cm. The other pesticides showed lower mobility in the studied soil. The calculated values to AF were 7.06E-12 (carbendazim), 5.08E-03 (carbofuran), 3.12E-17 (diuron), 6.66E-345 (alpha-endosulfan), 1.47E-162 (beta-endosulfan), 1.50E-06 (metolachlor), 3.51E-155 (chlorpyrifos). AF Model was useful to classify the pesticides' potential for contamination; however, that model underestimated pesticide leaching. PMID:17978955

  19. Leaching of iodide (I(-)) and iodate (IO3(-)) anions from synthetic layered double hydroxide materials.

    Science.gov (United States)

    Theiss, Frederick L; Ayoko, Godwin A; Frost, Ray L

    2016-09-15

    Several studies have previously demonstrated that layered double hydroxides (LDHs) show considerable potential for the adsorption of radioiodine from aqueous solution; however, few studies have demonstrated that these materials are able to store radioactive (131)I for an acceptable period. The leaching of iodide (I(-)) and iodate (IO3(-)) form Mg/Al LDHs has been carried out. Contact time appeared to be a more significant variable for the leaching of iodate (IO3(-)) compared to that of iodide (I(-)). Experimental results are fitted to the pseudo second order model, suggesting that diffusion is likely to be the rate-limiting step. The presence of carbonate in the leaching solution appeared to significantly increase the leaching of iodide (I(-)) as did the presence of chloride to a lesser extent. The maximum amount of iodate (IO3(-)) leached using ultrapure water as the leaching solution was 21% of the iodate (IO3(-)) originally present. The corresponding result for iodide (I(-)) was even lower at 3%. PMID:27309951

  20. Comparative characterization of sewage sludge compost and soil: Heavy metal leaching characteristics.

    Science.gov (United States)

    Fang, Wen; Wei, Yonghong; Liu, Jianguo

    2016-06-01

    The leaching and accumulation of heavy metals are major concerns following the land application of sewage sludge compost (SSC). We comparatively characterized SSC, the reference soil, and the SSC amended soil to investigate their similarities and differences regarding heavy metal leaching behavior and then to evaluate the effect of SSC land application on the leaching behavior of soil. Results showed that organic matter, including both of particulate organic matter (POM) and dissolved organic matter (DOM), were critical factors influencing heavy metal leaching from both of SSC and the soil. When SSC was applied to soil at the application rate of 48t/ha, the increase of DOM content slightly enhanced heavy metal leaching from the amended soil over the applicable pH domain (6alkaline pH, and led to more DOM-bound species in the liquid phases. However, the increase of POM content with the SSC application had less influence on the leaching behavior of heavy metals. The geochemical speciation modeling revealed that heavy metal speciation in the solid phase were similar between the reference soil and the amended soil. PMID:26897569

  1. Chemical characterization, leach, and adsorption studies of solidified low-level wastes

    International Nuclear Information System (INIS)

    Laboratory and field leaching experiments are beig conducted by Pacific Northwest Laboratory (PNL) to investigate the performance of solidified low-level nuclear waste in a typical, arid, near-surface disposal site. Under PNL's Special Waste Form Lysimeters-Arid Program, a field test facility was constructed to monitor the leaching of commercial solidified waste. Laboratory experiments were conducted to investigate the leaching and adsorption characteristics of the waste forms in contact with soil. Liquid radioactive wastes solidified in cement, vinyl ester-styrene, and bitumen were obtained from commercial boiling water and pressurized water reactors, and buried in a field leaching facility on the Hanford site in southeastern Washington State. Batch leaching, soil column adsorption, and soil/waste form column experiments were conducted in the laboratory, using small-scale cement waste forms and Hanford site ground water. The purpose of these experiments is to evaluate the ability of laboratory leaching tests to predict leaching under actual field conditions and to determine which mechanisms (i.e., diffusion, solubility, adsorption) actually control the concentration of radionuclides in the soil surrounding the waste form. Chemical and radionuclide analyses performed on samples collected from the field and laboratory experiments indicate strong adsorption of /sup 134,137/Cs and 85Sr onto the Hanford site sediment. Small amounts of 60Co are leached from the waste forms as very mobile species. Some 60Co migrated through the soil at the same rate as water. Chemical constituents present in the reactor waste streams also found at elevated levels in the field and laboratory leachates include sodium, sulfate, magnesium, and nitrate. Plausible solid phases that could be controlling some of the chemical and radionuclide concentrations in the leachate were identified using the MINTEQ geochemical computer code

  2. [Influence of ammonia on leaching behaviors of incineration fly ash and its geochemical modeling].

    Science.gov (United States)

    Guan, Zhen-Zhen; Chen, De-Zhen; Thomas, Astrup

    2013-06-01

    Incineration fly ash could be contaminated with NH3 that was slipped from the ammonia-based selective non-catalytic reduction(SNCR) process and from evaporation of municipal solid wastes' leachate involved in the wastes. This research was conducted to investigate the impacts of ammonia on leaching of dissolved organic carbon (DOC) and metals from incineration fly ash in the pH range of 3.66-12.44 with an active ammonia spike. A geochemical modeling software Visual MINTEQ was adopted to calculate the chemical speciation of metals under the leaching conditions to reveal the mechanism behind the impacts. It was proved that at pH > 9, the leaching of DOC increased significantly in the presence of high concentrations of ammonia (> or = 1 357 mg x L(-1)), but there was little effect when the ammonia level in eluates was not higher than 537 mg x L(-1). At pH or = 3 253 mg x L(-1)) mobilized Cd, Cu, Ni and Zn significantly due to the formation of soluble metal-ammonia complexes, and the leaching rates reached their peaks at pH around 9; however, ammonia had little impacts on Al and Pb leaching within this pH range. At pH > 12, for Cd, Cu, Ni and Zn, their leaching species were predominantly in the form of hydroxide complexes. Under the ammonia concentration of 3253 mg x L(-1), the Visual MINTEQ modeling results were compared with the experimental data, and it was proved that the leaching of Al, Pb and Zn was mainly controlled by precipitation/dissolution modeling, while Cd, Cu and Ni were controlled by precipitation/dissolution and surface complexation/precipitation processes; Visual MINTEQ modeling could well describe the leaching behaviors of Al, Cu, Pb and Zn from incineration fly ash. PMID:23947071

  3. Transport, fate, and infectivity of Cryptosporidium parvum oocysts released from manure and leached through macroporous soil

    Science.gov (United States)

    Boyer, Douglas G.; Kuczynska, Ewa; Fayer, Ron

    2009-09-01

    A major mode of transmission of Cryptosporidium parvum, a widespread waterborne pathogen, is via contaminated drinking and recreational waters. Oocyst transport to surface water can occur by deposition of manure directly in the water or by wash off in surface runoff. Oocyst transport to groundwater is less straightforward and requires that the oocysts move through soil and bedrock to reach the water table. The purpose of this study was to determine the relative concentration and infectivity of C. parvum oocysts released from manure and leached through columns of undisturbed, macroporous karst soil. Modeling the fate of oocysts in this system over time can provide baseline data for evaluating real world events. Substantially more oocysts leached from undisturbed soil columns than disturbed soil columns. Oocyst survival studies using BALB/c neonatal suckling mice showed that about 85% of oocysts were infective at the beginning of leaching experiments. The oocyst infectivity decreased to about 20% after 12 weeks of leaching from soil columns maintained at 10°C. Cool (10°C) temperatures appear to increase survivability and maintain infectivity of many oocysts for 3 months or longer. Cool temperatures also appear to increase rates of release of oocysts from manure and leaching through soil. This study demonstrated that leaching is an important mechanism of oocyst transport in karst soils where infiltration capacities are high and long, continuous macropores exist. Karst groundwater systems might be especially vulnerable to contamination by leached oocysts, because of the prevalence of shallow soils and rapid groundwater movement. Oocysts leaching from soils into the epikarst could accumulate and remain viable for months until hydrological conditions are right for flushing the oocysts into the conduit flow system.

  4. Role of minerals properties on leaching process of weathered crust elution-deposited rare earth ore

    Institute of Scientific and Technical Information of China (English)

    肖燕飞; 刘向生; 冯宗玉; 黄小卫; 黄莉; 陈迎迎; 吴文远

    2015-01-01

    Granite belonged to intrusive rock and volcanic was extrusive rock. There may be many differences in their degree of weathering and mineral chemical composition. The present study investigated the minerals properties and the leaching mechanism of the granitic weathered crust elution-deposited rare earth ore from Longnan Rare Earth Mine area (LN ores) and volcanic weathered crust elution-deposited rare earth ore from Liutang Rare Earth Mine area (LT ores). The X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR) were used to characterize the phase of rare earth ores. The particle size distributions and main composition of the ore were also presented in this paper. The leaching mechanisms of two kinds of rare earth ores were analyzed with different kinetics models and could be described by the shrinking-core model. They were all inner diffusion-controlled leaching processes. The leaching equation of the kinetics of the LN ores could be expressed as:4 LN LN 1.096 10 2/3 0.377 8.314 0 2 3=0.1061 (1 ) Tr e tη η×−−− − −, leaching equation of kinetics of LT ores was 3 LT LT 4.640 10 2/3 0.411 8.314 0 32 3=8.33 101 (1 ) Tr e tη η×−− −×− − −. The rare earth leaching rate of LT ores was always lower in the same condition, and it would need more time and more (NH4)2SO4 consump-tion to achieve the same rare earth leaching efficiency, which would lead to more serious ammonia-nitrogen pollution. Therefore, magnesium salt was proposed as the leaching agent to eliminate ammonia-nitrogen pollution and further studies would be taken in the future.

  5. Chemical characterization, leach, and adsorption studies of solidified low-level wastes

    Energy Technology Data Exchange (ETDEWEB)

    Walter, M.B.; Serne, R.J.; Jones, T.L.; McLaurine, S.B.

    1986-12-01

    Laboratory and field leaching experiments are beig conducted by Pacific Northwest Laboratory (PNL) to investigate the performance of solidified low-level nuclear waste in a typical, arid, near-surface disposal site. Under PNL's Special Waste Form Lysimeters-Arid Program, a field test facility was constructed to monitor the leaching of commercial solidified waste. Laboratory experiments were conducted to investigate the leaching and adsorption characteristics of the waste forms in contact with soil. Liquid radioactive wastes solidified in cement, vinyl ester-styrene, and bitumen were obtained from commercial boiling water and pressurized water reactors, and buried in a field leaching facility on the Hanford site in southeastern Washington State. Batch leaching, soil column adsorption, and soil/waste form column experiments were conducted in the laboratory, using small-scale cement waste forms and Hanford site ground water. The purpose of these experiments is to evaluate the ability of laboratory leaching tests to predict leaching under actual field conditions and to determine which mechanisms (i.e., diffusion, solubility, adsorption) actually control the concentration of radionuclides in the soil surrounding the waste form. Chemical and radionuclide analyses performed on samples collected from the field and laboratory experiments indicate strong adsorption of /sup 134,137/Cs and /sup 85/Sr onto the Hanford site sediment. Small amounts of /sup 60/Co are leached from the waste forms as very mobile species. Some /sup 60/Co migrated through the soil at the same rate as water. Chemical constituents present in the reactor waste streams also found at elevated levels in the field and laboratory leachates include sodium, sulfate, magnesium, and nitrate. Plausible solid phases that could be controlling some of the chemical and radionuclide concentrations in the leachate were identified using the MINTEQ geochemical computer code.

  6. Microfluidic Leaching of Soil Minerals: Release of K+ from K Feldspar.

    Science.gov (United States)

    Ciceri, Davide; Allanore, Antoine

    2015-01-01

    The rate of K+ leaching from soil minerals such as K-feldspar is believed to be too slow to provide agronomic benefit. Currently, theories and methods available to interpret kinetics of mineral processes in soil fail to consider its microfluidic nature. In this study, we measure the leaching rate of K+ ions from a K-feldspar-bearing rock (syenite) in a microfluidic environment, and demonstrate that at the spatial and temporal scales experienced by crop roots, K+ is available at a faster rate than that measured with conventional apparatuses. We present a device to investigate kinetics of mineral leaching at an unprecedented simultaneous resolution of space (~101-102 μm), time (~101-102 min) and fluid volume (~100-101 mL). Results obtained from such a device challenge the notion that silicate minerals cannot be used as alternative fertilizers for tropical soils. PMID:26485160

  7. Test Results for Caustic Demand Measurements on Tank 241-AX-101 and Tank 241-AX-103 Archive Samples

    Energy Technology Data Exchange (ETDEWEB)

    Doll, Stephanie R. [Washington River Protection Solutions, Richland, WA (United States); Bolling, Stacie D. [Washington River Protection Solutions, Richland, WA (United States)

    2016-07-14

    Caustic demand testing is used to determine the necessary amount of caustic required to neutralize species present in the Hanford tank waste and obtain a target molarity of free hydroxide for tank corrosion control. The presence and quantity of hydroxide-consuming analytes are just as important in determining the caustic demand as is the amount of free hydroxide present. No single data point can accurately predict whether a satisfactory hydroxide level is being met as it is dependent on multiple factors (e.g., free hydroxide, buffers, amphoteric metal hydroxides, bicarbonate, etc.). This enclosure contains the caustic demand, scanning electron microscopy (SEM), polarized light microscopy (PLM), and X-ray diffraction (XRD) analysis for the tank 241-AX-101 (AX-101) and 241-AX-103 (AX-103) samples. The work was completed to fulfill a customer request outlined in the test plan, WRPS-1505529, “Test Plan and Procedure for Caustic Demand Testing on Tank 241-AX-101 and Tank 241-AX-103 Archive Samples.” The work results will provide a baseline to support planned retrieval of AX-101 and AX-103.

  8. Laboratory leach tests of phosphate/sulfate waste grout and leachate adsorption tests using Hanford sediment

    Energy Technology Data Exchange (ETDEWEB)

    Serne, R.J.; Martin, W.J.; McLaurine, S.B.; Airhart, S.P.; LeGore, V.L.; Treat, R.L.

    1987-12-01

    An assessment of the long-term risks posed by grout disposal at Hanford requires data on the ability of grout to resist leaching of waste species contained in the grout via contact with water that percolates through the ground. Additionally, data are needed on the ability of Hanford sediment (soil) surrounding the grout and concrete vault to retard migration of any wastes released from the grout. This report describes specific laboratory experiments that are producing empirical leach rate data and leachate-sediment adsorption data for Phosphate-Sulfate Waste (PSW) grout. The leach rate and adsorption values serve as inputs to computer codes used to forecast potential risk resulting from the use of ground water containing leached species. In addition, the report discusses other chemical analyses and geochemical computer code calculations that were used to identify mechanisms that control leach rates and adsorption potential. Knowledge of the controlling chemical and physical processes provides technical defensibility for using the empirical laboratory data to extrapolate the performance of the actual grout disposal system to the long time periods of interest. 59 refs., 83 figs., 18 tabs.

  9. Laboratory leach tests of phosphate/sulfate waste grout and leachate adsorption tests using Hanford sediment

    International Nuclear Information System (INIS)

    An assessment of the long-term risks posed by grout disposal at Hanford requires data on the ability of grout to resist leaching of waste species contained in the grout via contact with water that percolates through the ground. Additionally, data are needed on the ability of Hanford sediment (soil) surrounding the grout and concrete vault to retard migration of any wastes released from the grout. This report describes specific laboratory experiments that are producing empirical leach rate data and leachate-sediment adsorption data for Phosphate-Sulfate Waste (PSW) grout. The leach rate and adsorption values serve as inputs to computer codes used to forecast potential risk resulting from the use of ground water containing leached species. In addition, the report discusses other chemical analyses and geochemical computer code calculations that were used to identify mechanisms that control leach rates and adsorption potential. Knowledge of the controlling chemical and physical processes provides technical defensibility for using the empirical laboratory data to extrapolate the performance of the actual grout disposal system to the long time periods of interest. 59 refs., 83 figs., 18 tabs

  10. Investigation of Copper Ammonia Leaching from Smelter Slags: Characterization, Leaching and Kinetics

    Science.gov (United States)

    Bidari, Ehsan; Aghazadeh, Valeh

    2015-10-01

    Although ammonia leaching of copper from slags has been reported generally as a part of copper slag utilization methods, but no detailed studies have been reported in the literature. In this research, we tried to investigate the effect of different parameters on ammonia leaching of copper from copper smelting slag by identifying different copper-bearing phases and following them during leaching time. Mineralogical characterization of the smelting slag (1.7 pct Cu) was done using X-ray fluorescence, X-ray diffraction, optical microscopy, diagnostic leaching tests, and scanning electron microscopy. The characterization studies indicated that main copper-bearing species are soluble copper oxides and chalcocite along with minor amount of covellite, bornite, blister copper particles, and chalcopyrite. It was also found that only approximately 0.2 pct Cu was present in the insoluble bulk silicate phases. These results suggest that approximately 88 pct of the total copper of slag could be extracted by ammonia sulfide leaching. Leaching tests were carried out and the effects of various parameters, namely pH, ammonia concentration, temperature, presence of oxygen, stirring speed, and pulp density were examined on copper leaching. The temperature and stirring speed had the most pronounced effect on the copper leaching, whereas ammonia affected the leaching yield at low concentrations of ammonia. It was found that 78 pct of Cu could be extracted within 4 hours and under optimum conditions: T = 343 K (70 °C), 2M ammonia, pH 10.5, stirring speed = 900 rpm, pulp density = 10 pct ( w s/ v). The kinetic data were analyzed with the shrinking core models, and it was found that the leaching process is controlled by both the interfacial transfer and diffusion across the product layer and the activation energy is calculated to be 49.4 kJ mol-1.

  11. Leaching of actinides and technetium from simulated high-level waste glass

    International Nuclear Information System (INIS)

    Leach tests were conducted using a modified version of the IAEA procedure to study the behavior of glass waste-solution interactions. Release rates were determined for Tc, U, Np, Pu, Am, Cm, and Si in the following solutions: WIPP B salt brine, NaCl (287 g/l), NaCl (1.76 g/1), CaCl2 (1.66 g/l), NaHCO3 (2.52 g/l), and deionized water. The leach rates for all elements decreased an order of magnitude from their initial values during the first 20 to 30 days leaching time. The sodium bicarbonate solution produced the highest elemental release rates, while the saturated salt brine and deionized water in general gave the lowest release. Technetium has the highest initial release of all elements studied. The technetium release rates, however, decreased by over four orders of magnitude in 150 days of leaching time. In the prepared glass, technetium was phase separated, concentrating on internal pore surfaces. Neptunium, in all cases except CaCl2 solution, shows the highest actinide release rate. In general, curium and uranium have the lowest release rates. The range of actinide release rates is from 10-5 to 10-8 g/cm2/day. 25 figures, 7 tables

  12. Caustic Recycle from Hanford Tank Waste Using NaSICON Ceramic Membranes

    Energy Technology Data Exchange (ETDEWEB)

    Fountain, Matthew S.; Kurath, Dean E.; Sevigny, Gary J.; Poloski, Adam P.; Pendleton, J.; Balagopal, S.; Quist, M.; Clay, D.

    2008-07-15

    A sodium (Na) Super Ion Conductor (NaSICON), has been studied at Pacific Northwest National Laboratory (PNNL) to investigate their ability to separate sodium from radioactively contaminated sodium salt solutions for treating U.S. Department of Energy (DOE) tank wastes. Ceramatec Inc. developed and fabricated a membrane disk containing a proprietary NAS-GY material formulation that was electrochemically tested in a bench-scale apparatus with both a simulant and a radioactive tank-waste solution to determine the membrane performance when removing sodium from DOE tank wastes. Implementing this sodium separation process can result in significant cost savings by reducing the disposal volume of low-activity wastes and by producing a 19M NaOH feedstock product for recycle into waste treatment processes such as sludge leaching, regenerating ion exchange resins, inhibiting corrosion in carbon-steel tanks, or retrieving tank wastes. In actual waste tests, average sodium transport rates of 10.3 kg/day/m2 were achieved at average sodium transport efficiencies of 99%. The membrane was found to be highly selective to sodium ions resulting in no detectable cation transport except Na and a small quantity (0.04% to 0.06%) of 137Cs. An average decontamination factor of 2000 was observed with respect to 137Cs. As expected, Gibbsite precipitation was observed as OH- ions were depleted from the tank waste.

  13. Demonstration of Caustic-Side Solvent Extraction with Savannah River Site High Level Waste

    Energy Technology Data Exchange (ETDEWEB)

    Walker, D.D.

    2001-08-27

    Researchers successfully demonstrated the chemistry and process equipment of the Caustic-Side Solvent Extraction (CSSX) flowsheet for the decontamination of high level waste using a 33-stage, 2-cm centrifugal contactor apparatus at the Savannah River Technology Center. This represents the first CSSX process demonstration using Savannah River Site (SRS) high level waste. Three tests lasting 6, 12, and 48 hours processed simulated average SRS waste, simulated Tank 37H/44F composite waste, and Tank 37H/44F high level waste, respectively.

  14. Extraction of copper from bacterial leach solution using LIX98

    Institute of Scientific and Technical Information of China (English)

    柳建设; 邱冠周; 葛玉卿; 徐竞

    2002-01-01

    Extraction of copper from bacterial leach solution using Lix984 had been performed.It was found that the main factors influencing extraction yield of copper are the phase ratio and the concentration of extractant,following the pH of solution and extraction time and the order of factors influencing the separation rate is the pH of solution,the concentration of extractant,the extraction time and the phase ratio.The best conditions obtained by the orthogonal tests are as follows: the extractant concentration 4%,extraction time 3 min,phase ratio 1∶1,pH of solution 2.

  15. Arbuscular mycorrhizas reduce nitrogen loss via leaching.

    Directory of Open Access Journals (Sweden)

    Hamid R Asghari

    Full Text Available The capacity of mycorrhizal and non-mycorrhizal root systems to reduce nitrate (NO₃⁻ and ammonium (NH₄⁺ loss from soils via leaching was investigated in a microcosm-based study. A mycorrhiza defective tomato mutant and its mycorrhizal wildtype progenitor were used in this experiment in order to avoid the indirect effects of establishing non-mycorrhizal control treatments on soil nitrogen cycling and the wider soil biota. Mycorrhizal root systems dramatically reduced nitrate loss (almost 40 times less via leaching, compared to their non-mycorrhizal counterparts, following a pulse application of ammonium nitrate to experimental microcosms. The capacity of AM to reduce nutrient loss via leaching has received relatively little attention, but as demonstrated here, can be significant. Taken together, these data highlight the need to consider the potential benefits of AM beyond improvements in plant nutrition alone.

  16. Effects of increased deposition of atmospheric nitrogen on an upland moor: leaching of N species and soil solution chemistry

    International Nuclear Information System (INIS)

    This study was designed to investigate the leaching response of an upland moorland to long-term (10 yr) ammonium nitrate additions of 40, 80 and 120 kg N ha-1 yr-1 and to relate this response to other indications of potential system damage, such as acidification and cation displacement. Results showed increases in nitrate leaching only in response to high rates of N input, in excess of 96 and 136 kg total N input ha-1 yr-1 for the organic Oh horizon and mineral Eag horizon, respectively. Individual N additions did not alter ammonium leaching from either horizon and ammonium was completely retained by the mineral horizon. Leaching of dissolved organic nitrogen (DON) from the Oh horizon was increased by the addition of 40 kg N ha-1 yr-1, but in spite of increases, retention of total dissolved nitrogen reached a maximum of 92% and 95% of 80 kg added N ha-1 yr-1 in the Oh and Eag horizons, respectively. Calcium concentrations and calcium/aluminium ratios were decreased in the Eag horizon solution with significant acidification mainly in the Oh horizon leachate. Nitrate leaching is currently regarded as an early indication of N saturation in forest systems. Litter C:N ratios were significantly lowered but values remained above a threshold predicted to increase leaching of N in forests. - Nitrate leaching from an upland moor podsol was significantly increased only in response to rates of N deposition in excess of 96 kg N ha-1 yr-1

  17. Leaching of vanadium from stone coal with sulfuric acid

    Institute of Scientific and Technical Information of China (English)

    WANG Mingyu; XIAO Liansheng; LI Qinggang; WANG Xuewen; XIANG Xiaoyan

    2009-01-01

    The effects of roasting, mass ratio of H2SO4 to stone coal, leaching temperature, liquid-to-solid ratio, grinding fineness of stone coal, and two-stage counter-current leaching on the vanadium leaching ratio were studied. The results show that the vanadium leaching ratio of roasted stone coal through two-stage counter-current leaching can reach 65.1% at the mass ratio of H2SO4 to stone coal of 20%, leaching temperature for the production of vanadium from stone coal.

  18. Alkaline leaching of metal melting industry wastes dseparation of zinc and lead in the leach solution

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    In this work, a thorough examinations on the extractability of zinc and lead present in the steelmaking dusts using alkaline leaching process and the effectiveness of the zinc and lead separation in the resultant leaching solutions using sulfide precipitation method were made. It was found that only about 53% of zinc and over 70% of the lead could be leached out of the dusts, while the other 47% of zinc and 306 of lead were left in the leaching residues. The zinc and lead in the resultant leaching solution can be effectively and selectively separated. When the weight ratio of sodium sulfide (M. W. = 222-240) to Pb was kept at 1.8, the lead in the solution could be precipitated out quantitatively while all the zinc was remained in the solution. The zinc left in the solution can be further recovered by the addition of extra sodium sulfide with a weight ratio of sodium sulfide to the zinc over 2.6. The resultant filtrate can be recycled to the leaching of dust in the next leaching process.

  19. Leaching Rate Test of Nuclei Cs and Sr

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    A novel material-resemble verifiable cement for disposal of spent nuclear fuel reprocessing mediate-level waste has been developed. Waste form has been characterized for their compressive strength, phase composition. The cement formulation has been patented. In this experiment, the cement was mixed with simulated wastes for each composition 5 min at least. Ratio of waste to the cement is 0.45-0.55. After being packed into cylindrical molds, the grouts were cured for a period 28 days in a room temperature curing chamber at atmospheric pressure. The wasteform then

  20. Comparison of Leaching Rates of Glass-Ceramic and Glass

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    <正>With the increase of the burn-up of the nuclear fuel, the amounts of the long-lived radionuclides increase. The solubility of actinides such as plutonium in glass is very limited. Glass-ceramic as the new

  1. New parameters for a better evaluation of vegetative bioremediation, leaching, and phytodesalination.

    Science.gov (United States)

    Rabhi, Mokded; Atia, Abdallah; Abdelly, Chedly; Smaoui, Abderrazak

    2015-10-21

    Vegetative bioremediation of calcareous sodic and saline-sodic soils is a biological approach for soil desalination by plants. It is based on three main processes: (i) sodium release from cation exchange sites, (ii) its leaching, and/or (iii) phytodesalination (Na(+) uptake by plant roots and its accumulation in shoots). Leaching needs sufficient rainfall and/or adequate irrigation. Thus, under non-leaching conditions, phytodesalination is the only existing process in terms of sodium removal. Several works tried to evaluate these processes; used plants were grown in field, in lysimeters, or in non-perforated pots. The evaluation of vegetative bioremediation, leaching, and phytodesalination was mainly based on plant analyses (including biomass production, sodium accumulation, test culture, and co-culture) and soil analyses (porosity, salinity, sodicity...). Nevertheless, used parameters are not enough to ensure comparisons between results found in different investigations. The present study introduces new parameters like phytodesalination efficiency, yield, and rate as well as vegetative bioremediation and leaching yields and rates. Our study is also illustrated by an estimation of all parameters for several previously-published data from our own works and those of other authors. Obtained results showed usefulness of these parameters and some of them can be extended to heavy metal phytoexraction. PMID:26254216

  2. New parameters for a better evaluation of vegetative bioremediation, leaching, and phytodesalination.

    Science.gov (United States)

    Rabhi, Mokded; Atia, Abdallah; Abdelly, Chedly; Smaoui, Abderrazak

    2015-10-21

    Vegetative bioremediation of calcareous sodic and saline-sodic soils is a biological approach for soil desalination by plants. It is based on three main processes: (i) sodium release from cation exchange sites, (ii) its leaching, and/or (iii) phytodesalination (Na(+) uptake by plant roots and its accumulation in shoots). Leaching needs sufficient rainfall and/or adequate irrigation. Thus, under non-leaching conditions, phytodesalination is the only existing process in terms of sodium removal. Several works tried to evaluate these processes; used plants were grown in field, in lysimeters, or in non-perforated pots. The evaluation of vegetative bioremediation, leaching, and phytodesalination was mainly based on plant analyses (including biomass production, sodium accumulation, test culture, and co-culture) and soil analyses (porosity, salinity, sodicity...). Nevertheless, used parameters are not enough to ensure comparisons between results found in different investigations. The present study introduces new parameters like phytodesalination efficiency, yield, and rate as well as vegetative bioremediation and leaching yields and rates. Our study is also illustrated by an estimation of all parameters for several previously-published data from our own works and those of other authors. Obtained results showed usefulness of these parameters and some of them can be extended to heavy metal phytoexraction.

  3. Leach tests on grouts made with actual and trace metal-spiked synthetic phosphate/sulfate waste

    Energy Technology Data Exchange (ETDEWEB)

    Serne, R.J.; Martin, W.J.; LeGore, V.L.; Lindenmeier, C.W.; McLaurine, S.B.; Martin, P.F.C.; Lokken, R.O.

    1989-10-01

    Pacific Northwest Laboratory conducted experiments to produce empirical leach rate data for phosphate-sulfate waste (PSW) grout. Effective diffusivities were measured for various radionuclides ({sup 90}Sr, {sup 99}Tc, {sup 14}C, {sup 129}I, {sup 137}Cs, {sup 60}Co, {sup 54}Mn, and U), stable major components (NO{sub 3}{sup {minus}}, SO{sub 4}{sup 2{minus}}, H{sub 3}BO{sub 3}, K and Na) and the trace constituents Ag, As, Cd, Hg, Pb, and Se. Two types of leach tests were used on samples of actual PSW grout and synthetic PSW grout: the American Nuclear Society (ANS) 16.1 intermittent replacement leach test and a static leach test. Grout produced from both synthetic and real PSW showed low leach rates for the trace metal constituents and most of the waste radionuclides. Many of the spiked trace metals and radionuclides were not detected in any leachates. None of the effluents contained measurable quantities of {sup 137}Cs, {sup 60}Co, {sup 54}Mn, {sup 109}Cd, {sup 51}Cr, {sup 210}Pb, {sup 203}Hg, or As. For those trace species with detectable leach rates, {sup 125}I appeared to have the greatest leach rate, followed by {sup 99}Tc, {sup 75}Se, and finally U, {sup 14}C, and {sup 110m}Ag. Leach rates for nitrate are between those for I and Tc, but there is much scatter in the nitrate data because of the very low nitrate inventory. 32 refs., 6 figs., 15 tabs.

  4. A functional study of caustic strictures of the esophagus in children

    Directory of Open Access Journals (Sweden)

    E.A.L. Da-Costa-Pinto

    2004-11-01

    Full Text Available The objective of the present study was to assess esophageal motor function in 21 children (7.5 ± 2.9 years with caustic strictures. Esophageal manometry was performed using a water-infusion system interfaced with a polygraph and displayed on a computer screen. The data were compared with those obtained from 9 healthy children. Radionuclide transit was determined by studying deglutition of a single bolus of 99mTc pertechnetate in 10 ml of water. Non-peristaltic low-amplitude and long-duration waves were the most common findings detected in patients with strictures longer than 20% of esophageal length (N = 11. Compared with the control group, these patients presented lower mean amplitude and longer mean duration of waves (24.4 ± 11.2 vs 97.9 ± 23.7 mmHg, P < 0.05, and 6.7 ± 2.4 vs 1.6 ± 0.1 s, P < 0.05, respectively. Six patients presented low-amplitude waves just below the constricted site. Ten children presented delayed esophageal transit. There was an association between dysphagia and abnormalities on manometry (P = 0.02 and between symptoms and scintigraphy data (P = 0.01. Dysphagia in caustic strictures is due to esophageal motility abnormalities, which are closely related to the scarred segment.

  5. Additives effects on crystallization and morphology in a novel caustic aluminate solution decomposition process

    Institute of Scientific and Technical Information of China (English)

    Ying ZHANG; Sbili ZHENG; Yifei ZHANG; Hongbin XU; Yi ZHANG

    2009-01-01

    A novel process of caustic aluminate solution decomposition by alcohol medium was developed by the Institute of Process Engineering, Chinese Academy of Sciences in order to solve the problem of low decomposi-tion ratio in the traditional Bayer seeded hydrolysis process. In this research, effects of additives on the crystallization ratio, secondary particle size and morphol-ogy of aluminum hydroxide in the new process were studied to obtain high-quality products. On the basis of primary selection of additives, an orthogonal design L9(34)was used as a chemometric method to investigate the effects of additives. The studied parameters include the reaction style, quantity of additives, caustic soda concen-tration, as well as the combination manner. The crystal-lization ratios of sodium aluminate solution and crystal size of aluminum hydroxide, determined by ICP-OES, SEM and MLPSA (Malvern Laser Particle Size Analyzer), were used to evaluate the effects of the additives. The results showed that different combination manners could promote agglomeration or dispersion. An additive composed by Tween 80 and PEG 200 could promote agglomeration,while a spot of PEG species had a relatively strong dispersion effect. However, the additives had little effects on the crystallization ratios. According to the Raman spectra result, the added alcohol medium might serve as a kind of solvent.

  6. H-Area Acid/Caustic Basin groundwater monitoring report. Second quarter 1994

    International Nuclear Information System (INIS)

    During second quarter 1994, samples collected from the four HAC monitoring wells at the H-Area Acid/Caustic Basin received comprehensive analyses (exclusive of boron and lithium) and turbidity measurements. Monitoring results that exceeded the final Primary Drinking Water Standards (PDWS) or the Savannah River Site (SRS) flagging criteria or turbidity standard during the quarter are the focus of this report. Tritium exceeded the final PDWS in all four HAC wells during second quarter 1994. Carbon tetrachloride exceeded the final PDWS in well HAC 4. Aluminum exceeded its Flag 2 criterion in wells HAC 2, 3, and 4. Iron was elevated in wells HAC 1, 2, and 3. Manganese exceeded its Flag 2 criterion in well HAC 3. Specific conductance and total organic halogens were elevated in well HAC 2. No well samples exceeded the SRS turbidity standard. Groundwater flow direction in the water stable beneath the H-Area Acid/Caustic Basin was to the west during second quarter 1994. During previous quarters, the groundwater flow direction has been consistently to the northwest or the north-northwest. This apparent change in flow direction may be attributed to the lack of water elevations for wells HTF 16 and 17 and the anomalous water elevations for well HAC 2 during second quarter

  7. Direct anodic hydrochloric acid and cathodic caustic production during water electrolysis

    Science.gov (United States)

    Lin, Hui-Wen; Cejudo-Marín, Rocío; Jeremiasse, Adriaan W.; Rabaey, Korneel; Yuan, Zhiguo; Pikaar, Ilje

    2016-02-01

    Hydrochloric acid (HCl) and caustic (NaOH) are among the most widely used chemicals by the water industry. Direct anodic electrochemical HCl production by water electrolysis has not been successful as current commercially available electrodes are prone to chlorine formation. This study presents an innovative technology simultaneously generating HCl and NaOH from NaCl using a Mn0.84Mo0.16O2.23 oxygen evolution electrode during water electrolysis. The results showed that protons could be anodically generated at a high Coulombic efficiency (i.e. ≥ 95%) with chlorine formation accounting for 3 ~ 5% of the charge supplied. HCl was anodically produced at moderate strengths at a CE of 65 ± 4% together with a CE of 89 ± 1% for cathodic caustic production. The reduction in CE for HCl generation was caused by proton cross-over from the anode to the middle compartment. Overall, this study showed the potential of simultaneous HCl and NaOH generation from NaCl and represents a major step forward for the water industry towards on-site production of HCl and NaOH. In this study, artificial brine was used as a source of sodium and chloride ions. In theory, artificial brine could be replaced by saline waste streams such as Reverse Osmosis Concentrate (ROC), turning ROC into a valuable resource.

  8. Microbial Fuel Cell-driven caustic potash production from wastewater for carbon sequestration.

    Science.gov (United States)

    Gajda, Iwona; Greenman, John; Melhuish, Chris; Santoro, Carlo; Ieropoulos, Ioannis

    2016-09-01

    This work reports on the novel formation of caustic potash (KOH) directly on the MFC cathode locking carbon dioxide into potassium bicarbonate salt (kalicinite) while producing, instead of consuming electrical power. Using potassium-rich wastewater as a fuel for microorganisms to generate electricity in the anode chamber, has resulted in the formation of caustic catholyte directly on the surface of the cathode electrode. Analysis of this liquid has shown to be highly alkaline (pH>13) and act as a CO2 sorbent. It has been later mineralised to kalicinite thus locking carbon dioxide into potassium bicarbonate salt. This work demonstrates an electricity generation method as a simple, cost-effective and environmentally friendly route towards CO2 sequestration that perhaps leads to a carbon negative economy. Moreover, it shows a potential application for both electricity production and nutrient recovery in the form of minerals from nutrient-rich wastewater streams such as urine for use as fertiliser in the future. PMID:27133363

  9. Kinetics and Modeling of Chemical Leaching of Sphalerite Concentrate Using Ferric Iron in a Redox-controlled Reactor

    Institute of Scientific and Technical Information of China (English)

    宋健; 高玲; 林建群; 吴洪斌; 林建强

    2013-01-01

    This work presents a study for chemical leaching of sphalerite concentrate under various constant Fe3+concentrations and redox potential conditions. The effects of Fe3+ concentration and redox potential on chemical leaching of sphalerite were investigated. The shrinking core model was applied to analyze the experimental results. It was found that both the Fe3+ concentration and the redox potential controlled the chemical leaching rate of sphalerite. A new kinetic model was developed, in which the chemical leaching rate of sphalerite was proportional to Fe3+concentration and Fe3+/Fe2+ratio. All the model parameters were evaluated from the experimental data. The model predictions fit well with the experimental observed values.

  10. Comparison of ultrasonic-assisted and regular leaching of germanium from by-product of zinc metallurgy.

    Science.gov (United States)

    Zhang, Libo; Guo, Wenqian; Peng, Jinhui; Li, Jing; Lin, Guo; Yu, Xia

    2016-07-01

    A major source of germanium recovery and also the source of this research is the by-product of lead and zinc metallurgical process. The primary purpose of the research is to investigate the effects of ultrasonic assisted and regular methods on the leaching yield of germanium from roasted slag containing germanium. In the study, the HCl-CaCl2 mixed solution is adopted as the reacting system and the Ca(ClO)2 used as the oxidant. Through six single factor (leaching time, temperature, amount of Ca(ClO)2, acid concentration, concentration of CaCl2 solution, ultrasonic power) experiments and the comparison of the two methods, it is found the optimum collective of germanium for ultrasonic-assisted method is obtained at temperature 80 °C for a leaching duration of 40 min. The optimum concentration for hydrochloric acid, CaCl2 and oxidizing agent are identified to be 3.5 mol/L, 150 g/L and 58.33 g/L, respectively. In addition, 700 W is the best ultrasonic power and an over-high power is adverse in the leaching process. Under the optimum condition, the recovery of germanium could reach up to 92.7%. While, the optimum leaching condition for regular leaching method is same to ultrasonic-assisted method, except regular method consume 100 min and the leaching rate of Ge 88.35% is lower about 4.35%. All in all, the experiment manifests that the leaching time can be reduced by as much as 60% and the leaching rate of Ge can be increased by 3-5% with the application of ultrasonic tool, which is mainly thanks to the mechanical action of ultrasonic.

  11. Comparison of ultrasonic-assisted and regular leaching of germanium from by-product of zinc metallurgy.

    Science.gov (United States)

    Zhang, Libo; Guo, Wenqian; Peng, Jinhui; Li, Jing; Lin, Guo; Yu, Xia

    2016-07-01

    A major source of germanium recovery and also the source of this research is the by-product of lead and zinc metallurgical process. The primary purpose of the research is to investigate the effects of ultrasonic assisted and regular methods on the leaching yield of germanium from roasted slag containing germanium. In the study, the HCl-CaCl2 mixed solution is adopted as the reacting system and the Ca(ClO)2 used as the oxidant. Through six single factor (leaching time, temperature, amount of Ca(ClO)2, acid concentration, concentration of CaCl2 solution, ultrasonic power) experiments and the comparison of the two methods, it is found the optimum collective of germanium for ultrasonic-assisted method is obtained at temperature 80 °C for a leaching duration of 40 min. The optimum concentration for hydrochloric acid, CaCl2 and oxidizing agent are identified to be 3.5 mol/L, 150 g/L and 58.33 g/L, respectively. In addition, 700 W is the best ultrasonic power and an over-high power is adverse in the leaching process. Under the optimum condition, the recovery of germanium could reach up to 92.7%. While, the optimum leaching condition for regular leaching method is same to ultrasonic-assisted method, except regular method consume 100 min and the leaching rate of Ge 88.35% is lower about 4.35%. All in all, the experiment manifests that the leaching time can be reduced by as much as 60% and the leaching rate of Ge can be increased by 3-5% with the application of ultrasonic tool, which is mainly thanks to the mechanical action of ultrasonic. PMID:26964934

  12. Leaching of Main Elements of Glass Immersed in Beishan Groundwater

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    <正>The leaching quantities of the elements from the HLW are very important parameters for the safety assessments of the repository of high level radioactive wastes. It is necessary to study the leaching

  13. Leaching of Plastic Additives to Marine Organisms

    NARCIS (Netherlands)

    Koelmans, A.A.; Besseling, E.; Foekema, E.M.

    2014-01-01

    It is often assumed that ingestion of microplastics by aquatic species leads to increased exposure to plastic additives. However, experimental data or model based evidence is lacking. Here we assess the potential of leaching of nonylphenol (NP) and bisphenol A (BPA) in the intestinal tracts of Areni

  14. Heap leaching of clay ish uranium ores

    International Nuclear Information System (INIS)

    This paper describes an experimental facility, built near El Lobo mine. In it we study the beneficiation of low-grade uranium ore. The mineral has a great amount of clay and fines. The flow-sheet used has four steps: head leaching, ph-ajustement, ion-exchange and participation. We show, also, the most interesting results. (Author)

  15. Leaching performance of imidazolium based ionic liquids in the presence of hydrogen peroxide for recovery of metals from brass waste

    OpenAIRE

    Kilicarslan, Ayfer; Saridede, Muhlis N.

    2016-01-01

    The application of ionic liquids (ILs), 1-methylimidazolium hydrogen sulfate (HmimHSO4), 1-ethyl-3-methylimidazolium hydrogen sulfate (HmimHSO4) and 1-butyl-3-methylimidazolium chloride (BmimCl) as leaching agents was investigated in the leaching of copper and zinc from brass waste in the presence of an oxidant, hydrogen peroxide (H2O2). Factors that affect copper and zinc dissolution rates such as ionic liquid concentration, time and temperature were investigated. The results indicated that ...

  16. Mineralogy and uranium leaching of ores from Triassic Peribaltic sandstones

    OpenAIRE

    Gajda, Dorota; Kiegiel, Katarzyna; Zakrzewska-Koltuniewicz, Grazyna; Chajduk, Ewelina; Bartosiewicz, Iwona; Wolkowicz, Stanislaw

    2014-01-01

    The recovery of uranium and other valuable metals from Polish Peribaltic sandstones were examined. The solid–liquid extraction is the first stage of the technology of uranium production and it is crucial for the next stages of processing. In the laboratory experiments uranium was leached with efficiencies 71–100 % by acidic lixiviants. Satisfactory results were obtained for the alkaline leaching process. Almost 100 % of uranium was leached with alkaline carbonate solution. In post leaching so...

  17. Enhancements of LEACH Algorithm for Wireless Networks: A Review

    Directory of Open Access Journals (Sweden)

    M. Madheswaran

    2013-12-01

    Full Text Available Low Energy Adaptive Clustering Hierarchy (LEACH protocol is the first hierarchical cluster based routing protocol successfully used in the Wireless Sensor Networks (WSN. In this paper, various enhancements used in the original LEACH protocol are examined. The basic operations, advantages and limitations of the modified LEACH algorithms are compared to identify the research issues to be solved and to give the suggestions for the future proposed routing algorithms of wireless networks based on LEACH routing algorithm.

  18. Diffusion-based leaching models for glassy waste forms

    International Nuclear Information System (INIS)

    Most scenarios for the disposal of high-level nuclear wastes assume burial under conditions in which only a limited quantity of groundwater will contact the waste form. In order to model these conditions, it is necessary to describe the release of species from a waste form matrix in contact with a limited volume of leachant in which the concentration of released species is not zero and is itself a function of release rate. Eight leaching models are presented that include the cases of a dissolving and a nondissolving matrix, finite, infinite, and replenished leachant volumes, and a matrix covered by a surface layer with different properties. The equations that describe these models assume a linear concentration profile of the diffusing species within the waste form and apply Fick's first law to obtain the leach rate. In three cases a direct comparison is possible between the solutions of these equations and solutions obtained by use of the diffusion equation derived from Fick's second law. Good agreement is found. The equations given are convenient for use with programmable calculators

  19. Embryotoxicity assays for leached components from dental restorative materials

    Directory of Open Access Journals (Sweden)

    Mummolo Stefano

    2011-10-01

    Full Text Available Abstract Background Currently, there are no suitable assays available to evaluate the embryotoxicity of leached components from restorative dental materials. Methods The effect of the medium conditioned by composites and amalgam on mouse blastocysts in vitro was tested. The materials were also subcutaneously implanted, and the effect of the medium supplemented with serum from the host blood was evaluated in the embryotoxicity assay. The embryo implantation rate in the material-transplanted mothers was also evaluated. Results The results show that while the culture in media conditioned by amalgams did not affect blastocyst development, the medium conditioned by composites caused blastocyst degeneration and apoptosis. The development of blastocysts in a medium containing serum obtained from animals after transplantation was, however, without effect. Finally, inconsistent reduction in the implantation rate in transplanted mothers was observed. Conclusions In this study, we provide examples of in vitro and in vivo tests that may be used to evaluate embryotoxicity for dental materials. Our results show that leached components from our composite-material induced embryotoxicity in vitro, however, no toxicity was observed when subcutaneously implanted in vivo. This highlights the necessity of integrated in vitro and in vivo tests for valuable predictive estimation of embryotoxicity for complex materials.

  20. Pesticide leaching through sandy and loamy fields - long-term lessons learnt from the Danish Pesticide Leaching Assessment Programme.

    Science.gov (United States)

    Rosenbom, Annette E; Olsen, Preben; Plauborg, Finn; Grant, Ruth; Juhler, René K; Brüsch, Walter; Kjær, Jeanne

    2015-06-01

    The European Union authorization procedure for pesticides includes an assessment of the leaching risk posed by pesticides and their degradation products (DP) with the aim of avoiding any unacceptable influence on groundwater. Twelve-year's results of the Danish Pesticide Leaching Assessment Programme reveal shortcomings to the procedure by having assessed leaching into groundwater of 43 pesticides applied in accordance with current regulations on agricultural fields, and 47 of their DP. Three types of leaching scenario were not fully captured by the procedure: long-term leaching of DP of pesticides applied on potato crops cultivated in sand, leaching of strongly sorbing pesticides after autumn application on loam, and leaching of various pesticides and their DP following early summer application on loam. Rapid preferential transport that bypasses the retardation of the plow layer primarily in autumn, but also during early summer, seems to dominate leaching in a number of those scenarios. PMID:25771345

  1. Leaching of Bornite Produced from the Sulfurization of Chalcopyrite

    Science.gov (United States)

    Veloso, T. C.; Paiva, P. R. P.; Silva, C. A.; Leão, V. A.

    2016-06-01

    The pyrometallurgical route accounts for 80 pct of world metallic copper production, because chalcopyrite, the most abundant copper sulfide, is refractory to hydrometallurgical treatment. However, pyrometallurgical routes are quite restrictive as far as copper concentrates are concerned mainly owing to limits on the concentration of impurities, such as fluorine, chlorine, and arsenic that can be tolerated. Such concentrates require innovative processing solutions because their market value is greatly reduced. A potential alternative is the transformation of chalcopyrite to a sulfide amenable to leaching, such as chalcocite, covellite, or bornite, through treatment in either aqueous or gaseous environments. In this study, the sulfurization of a chalcopyrite concentrate containing 78 pct CuFeS2 in the presence of gaseous sulfur was investigated, with the goal of demonstrating its conversion to the leachable phases, i.e., bornite and covellite. The concentrate was reacted with elemental sulfur in a tubular furnace at temperatures ranging from 573 K to 723 K (300 °C to 450 °C), followed by atmospheric leaching in an Fe(III)-bearing solution. The mineral phases in the sample were quantified using the Rietveld method, and it was shown that at temperatures below 673 K (400 °C) chalcopyrite was converted to covellite (41 pct) and pyrite (34 pct), whereas at temperatures above these, the reaction products were bornite (45 pct) and pyrite (31 pct). Leaching tests [6 hours at 353 K (80 °C)] showed significantly higher copper extraction rates after sulfurization (90 pct) than those using the raw chalcopyrite concentrate (15 pct).

  2. Cuspidal caustic and focusing of acoustical waves generated by a parametric array onto a concave reflecting surface

    Science.gov (United States)

    Castagnède, Bernard; Sahraoui, Sohbi; Tournat, Vincent; Tahani, Najat

    2009-09-01

    The present Note is devoted to the study of the so-called cuspidal caustic at the surface of a hemi-cylindrical reflector illuminated with plane waves. In order to generate low frequency (e.g. in the range of 4 kHz) acoustical plane waves, a commercially available parametric array has been used. It produces powerful ultrasonic carrier waves at 40 kHz which can be electronically modulated between 200 Hz and 10 kHz. Further self-demodulation process during propagation in air generates an ultra-directive acoustical field (i.e. quasi-planar wavefronts) enabling to accurately study the focusing process occurring along the cuspidal caustic. The focusing coefficient can be computed locally by using two numerical tools, on one hand by computing the density of tangent rays to the caustic, and on the other hand by using some numerical results provided by a ray tracing algorithm. Some preliminary experimental data are then provided in order to validate the numerical predictions (spatial position of the caustic and focusing coefficient). To cite this article: B. Castagnède et al., C. R. Mecanique 337 (2009).

  3. Mechanism of influence of ferric ion on electrogenerative leaching of sulfide minerals with FeCl3

    Institute of Scientific and Technical Information of China (English)

    WANG Shao-fen; FANG Zheng

    2006-01-01

    A dual cell system was used to study the influence of ferric ion on the electrogenerative leaching of sulfide minerals.Reaction mechanisms for the ferric chloride electrogenerative leaching of a series of sulfide minerals were proposed based on the data collected from the dual cell experiments. The influences of ferric ion on the electrogenerative leaching of sulfide minerals are similar. Ferric ion plays an important role on limiting the electrogenerative leaching rate at a relatively low concentration of FeCl3(about less than 0.15 mol/L). The mathematical models based on the Butler-Volmer relation were delineated, and kinetic equations with respect to ferric ions for each sulfide mineral were obtained. The kinetic equations show that when the concentration of ferric ion is relatively low, the electrogenerative leaching rates are predicted to be proportional to 6/7, 4/5, 2/3 and 2/3 order of ferric ion for nickel concentrate, chalcopyrite concentrate, sphalerite and galena respectively. As the concentration of ferric ion increase, the correlative dependence between electrogenerative leaching rate and concentration of ferric ion becomes weak. The above conclusions are in agreement with the experimental results.

  4. Phosphorus leaching from loamy sand and clay loam topsoils after application of pig slurry

    OpenAIRE

    Liu, Jian; Aronsson, Helena; Bergström, Lars; Sharpley, Andrew

    2012-01-01

    Appropriate management of animal waste is essential for guaranteeing good water quality. A laboratory leaching study with intact soil columns was performed to investigate the risk of phosphorus (P) leaching from a clay loam and a loamy sand. The columns (0.2 m deep) were irrigated before and after application of pig slurry on the surface or after incorporation, or application of mineral P, each at a rate of 30 kg P ha-1. The two soils had different initial P contents (i.e. the ammonium lactat...

  5. Development of SO2-O2 system as an oxidant at uranium leaching processes

    International Nuclear Information System (INIS)

    The oxidation of Fe2+ in uranium leaching solutions with gaseous mixture of SO2 and air has been studied. The variables studied include H2SO4 concentration, temperature, SO2 concentration and time. The oxidation rate was founded to increase greatly with an increase in the solution temperature. The almost total oxidation of Fe2+ is readily achieved at 95 deg C. By appropriately adjusting the temperature of solution and SO2/O2 in the gas, oxidation of ferrous ion and generation of sulphuric acid can be carried out. It was founded that solutions produced by such oxidation processing are very suitable for the uranium ore leaching. (author)

  6. Microbial leaching of iron from pyrite by moderate thermophile chemolithotropic bacteria

    International Nuclear Information System (INIS)

    The present work was aimed at studying the bioleachability of iron from pyrite by the selected moderately thermophilic strains of acidophilic chemolithotrophic and acidophilic heterotrophic bacteria. These included Sulfobacillus thermosulfidooxidans (chemolithotroph) and an un-identified strain of acidophilic heterotroph (code 6A1TSB) isolated from local environments. As compared to inoculated flasks, dissolution of metal (due to acid leaching) was significantly low in the un-inoculated control flasks in all the experiments in ore. A decrease in the bioleaching activity was observed at the later stages of bioleaching of metal from ore. Among the strategies adopted to enhance the metal leaching rates, a mixed consortium of the metal adapted cultures of the above-mentioned bacteria was found to exhibit the maximum metal leaching efficiency. In all the flasks where high metal leaching rates were observed, concomitantly biomass production rates were also high indicating high growth rates. It showed that the metal bioleaching capability of the bacteria was associated with their growth. Pyrite contained 42% iron. (author)

  7. Recovery of struvite from animal wastewater and its nutrient leaching loss in soil

    Energy Technology Data Exchange (ETDEWEB)

    Rahman, Md M.; Liu Yinghao [Laboratory of Livestock Environment, College of Animal Life Science, Kangwon National University, Chunchon 200-701 (Korea, Republic of); Kwag, Jung-Hoon [National Institute of Animal Science, RDA, Suwon 441-350 (Korea, Republic of); Ra, Chang Six, E-mail: changsix@kangwon.ac.kr [Laboratory of Livestock Environment, College of Animal Life Science, Kangwon National University, Chunchon 200-701 (Korea, Republic of)

    2011-02-28

    Contaminants in swine wastewater were recovered in the form of struvite, a crystal of magnesium ammonium phosphate (MAP), using a newly designed process, and the leaching loss of MAP in soil was examined. The continuous flow process was operated under optimal conditions: 1.0 molar ratio of magnesium (Mg) addition with respect to orthophosphate (OP) and an aeration rate of 0.73 L/L min. Five treatments were performed with three replications for soil pH and nutrient leaching loss tests. It was found that 93% of the OP in the swine wastewater was crystallized, and the MAP crystal formation was verified by X-ray diffraction (XRD) and scanning electron microscope (SEM) analyses. The analyses revealed that the pattern of pH change and N leaching losses for MAP-treated soil were remarkably different from those for fused super phosphate (FSP)-urea-treated soils. The pH levels for the control and FSP-urea-treated soils after a five-week experiment were unchanged or slightly decreased, whereas an increase in pH was observed in the MAP-treated soils. Leaching loss of N was higher in FSP-urea treatments, with MAP treatments showing N losses of only 1.93 and 2.05%, respectively, while FSP-urea treatments showed N losses of 7.82 and 6.47%, respectively, during the same period. Phosphate (P) leaching was very slow in both MAP- and FSP-treated groups.

  8. A Routing Protocol Orphan-Leach to Join Orphan Nodes in Wireless Sensor Network

    Directory of Open Access Journals (Sweden)

    Wassim JERBI

    2016-04-01

    Full Text Available The hierarchical routing protocol LEACH (Low Energy Adaptive Clustering Hierarchy is referred to as the basic algorithm of distributed c lustering protocols. LEACH allows clusters formation. Each cluster has a leader called Cluster Head (CH. The selection of CHs is made with a probabilistic calculation. It is supposed th at each non-CH node join a cluster and becomes a cluster member. Nevertheless, some CHs ca n be concentrated in a specific part of the network. Thus several sensor nodes cannot reach any CH. As a result, the remaining part of the controlled field will not be covered; some sensor n odes will be outside the network. To solve this problem, we propose O-LEACH (Orphan Low Energy Adap tive Clustering Hierarchy a routing protocol that takes into account the orphan nodes. Indeed, a cluster member will be able to play the role of a gateway which allows the joining of o rphan nodes. If a gateway node has to connect a important number of orphan nodes, thus a sub-cluster is created and the gateway node is considered as a CH’ for connected orphans. As a result, orphan nodes become able to send their data messages to the CH which performs i n turn data aggregation and send aggregated data message to the CH. The WSN applicat ion receives data from the entire network including orphan nodes. The simulation results show that O-LEACH performs b etter than LEACH in terms of connectivity rate, energy, scalability and coverage .

  9. Leaching of marine manganese nodules by acidophilic bacteria growing on elemental sulfur

    Science.gov (United States)

    Konishi, Yasuhiro; Asai, Satoru; Sawada, Yuichi

    1997-02-01

    This article describes the bioleaching of manganese nodules by thermophilic and mesophilic sulfuroxidizing bacteria, in which oxidized sulfur compounds are biologically produced from elemental sulfur added to liquid medium and are simultaneously used to leach nodules. The thermophile Acidianus brierleyi solubilized the manganese nodules faster at 65 °C than did the mesophiles Thiobacillus ferrooxidans and Thiobacillus thiooxidans at 30 °C. Leaching experiments with A. brierleyi growing on elemental sulfur were used to optimize various process parameters, such as medium pH, initial sulfur-liquid loading ratio, and initial cell concentration. The observed dependencies of the leaching rates at a pH optimum on the initial amounts of elemental sulfur and A. brierleyi cells were qualitatively consistent with model simulations for microbial sulfur oxidation. Under the conditions determined as optimum, the leaching of nodule particles (-330+500 mesh) by A. brierleyi yielded 100 pct extraction of both copper and zinc within 4 days and high extractions of nickel (85 pct), cobalt (70 pct), and manganese (55 pct) for 10 days. However, the iron leaching was practically negligible.

  10. 含铁低品位氧化锌矿石浸出研究%Leaching of low grade zinc oxide ore bearing iron

    Institute of Scientific and Technical Information of China (English)

    杨金林; 马少健; 封金鹏; 王桂芳; 莫伟; 苏秀娟

    2011-01-01

    Alkaline leaching and sulfuric acid leaching of low grade zinc oxide ore bearing iron were studied in this work. The effecting factors, such as leaching time in different leaching agents and leaching temperature using ammonia-ammonium chloride as leaching agent, on zinc and iron leaching rates were investigated in alkaline leaching. The effecting factors, such as the initial sulfuric acid concentration, liquid-solid ratio, leaching temperature in different initial sulfuric acid concentrations and leaching time in different leaching temperatures, on zinc and iron leaching rates were studied in sulfuric acid leaching. The results showed that the leaching rates of zinc and iron were less than 50% and zero in alkaline leaching, respectively, while their leaching rates were greater than 87% and 45% in sulfuric acid leaching. The results of XRD analysis indicated that smithsonite was leached from the ore in alkaline leaching or in sulfuric acid leaching with low initial concentration such as less than 60 g/L or shorter time such as less than 10 min, and smithsonite and siderite were leached from the ore in sulfuric acid leaching with high initial concentration such as greater than 60 g/L or longer time such as more than 10 min.%针对含铁低品位氧化锌矿石,进行了碱性浸出与硫酸浸出研究.其中碱性浸出主要考察了采用不同浸出剂时浸出时间以及采用氨水——氯化铵作浸出剂时浸出温度对锌、铁浸出率的影响;硫酸浸出主要考察了硫酸初始浓度、矿浆液固比以及不同硫酸初始浓度时浸出温度和不同浸出温度时浸出时间对锌、铁浸出率的影响.研究结果表明,碱性浸出时锌浸出率不到50%,铁基本不被浸出;XRD分析结果说明,碱性浸出时浸出的主要是菱锌矿.硫酸浸出时锌浸出率最高可达87%以上,但铁的浸出率也在45%以上;XRD分析结果说明,硫酸浸出在低浓度如小于60 g/L或短浸出时间如10 min时浸出的主

  11. Nitrate leaching from a potato field using fuzzy inference system combined with genetic algorithm

    DEFF Research Database (Denmark)

    Shekofteh, Hosein; Afyuni, Majid M; Hajabbasi, Mohammad-Ali;

    2012-01-01

    The conventional application of nitrogen fertilizers via irrigation is likely to be responsible for the increased nitrate concentration in groundwater of areas dominated by irrigated agriculture. This requires appropriate water and nutrient management to minimize groundwater pollution...... and to maximize nutrient use efficiency. To fulfill these requirements, drip fertigation is an important alternative. This study deals with fuzzy modeling of nitrate leaching from a potato field under a drip fertigation system. In the first part of the study, a two-dimensional model (HYDRUS-2D) was used...... to simulate nitrate leaching from a sandy soil with varying emitter discharge rates and various amounts of fertilizer. The results from the modeling were used to train and validate a Mamdani fuzzy inference system (MFIS) in order to estimate nitrate leaching. The centers of triangular membership functions...

  12. Discovery and Characterization of a Caustic Crossing Microlensing Event in the Small Magellanic Cloud

    International Nuclear Information System (INIS)

    We present photometric observations and analysis of the second microlensing event detected toward the Small Magellanic Cloud (SMC), MACHO Alert 98-SMC-1. This event was detected early enough to allow intensive observation of the light curve. These observations revealed 98-SMC-1 to be the first caustic crossing binary microlensing event toward the Magellanic Clouds to be discovered in progress. Frequent coverage of the evolving light curve allowed an accurate prediction for the date of the source crossing out of the lens caustic structure. The caustic crossing temporal width, along with the angular size of the source star, measures the proper motion of the lens with respect to the source and thus allows an estimate of the location of the lens. Lenses located in the Galactic halo would have a velocity projected to the SMC of v∼1500 kms-1, while an SMC lens would typically have v∼60 kms-1. The event light curve allows us to obtain a unique fit to the parameters of the binary lens and to estimate the proper motion of the lensing system. We have performed a joint fit to the MACHO/GMAN data presented here, including recent EROS data of this event from Afonso and collaborators. These joint data are sufficient to constrain the time t* for the lens to move an angle equal to the source angular radius: t* =0.116±0.010 days. We estimate a radius for the lensed source of R* =1.1±0.1 Rcircle-dot from its unblended color and magnitude. This yields a projected velocity of v=76±10 kms-1. Only 0.12% of halo lenses would be expected to have a v value at least as small as this, while 38% of SMC lenses would be expected to have v as large as this. This implies that the lensing system is more likely to reside in the SMC than in the Galactic halo. Similar observations of future Magellanic Cloud microlensing events will help to determine the contribution of MACHOS to the Galaxy's dark halo. copyright copyright 1999. The American Astronomical Society

  13. Reductive Leaching of Iron from Sulfate Slag%硫酸烧渣还原浸取铁

    Institute of Scientific and Technical Information of China (English)

    金程; 李登新

    2012-01-01

    采用硫化物作助剂还原浸出硫酸烧渣中的三价铁.采用L9(43)四因素三水平正交试验,考察助剂用量、硫酸用量、温度、时间对浸出效果的影响,并确定最佳配比.结果表明:影响的显著顺序为助剂用量>时间>硫酸用量>温度.在下述最佳条件下铁浸取率可以达到87.8%:起始液固比2∶1、搅拌转速1 300 r/min、助剂用量17.2g、硫酸23 mL、85℃反应3h.%The ferric iron was reductive leached from sulfate slag with sulfide. The effects of leaching agent dosage, sulfuric acid consumption, reaction temperature and time on leaching rate of iron were investigated with L9(43) orthogonal test. The results show that the sequence of effecting is leaching agent dosage, reaction time, sulfuric acid consumption and reaction temperature. The iron leaching rate reaches 87. 8% on the following optimum conditions: ratio of liquid to solid of 2 : 1, stirring rate of 1 300 r/min, leaching a-gent dosage of 17. 2 g, sulfuric acid consumption of 23 mL, leaching temperature of 85 °C and leaching time of 3 h.

  14. THE CHEMICAL AND RADIATION RESISTANCE OF POLYPHENYLENE SULFIIDE AS ENCOUNTERED IN THE MODULAR CAUSTIC SIDE SOLVENT EXTRACTION PROCESSES

    Energy Technology Data Exchange (ETDEWEB)

    Fondeur, F.; Herman, D.; Poirier, M.; Fink, S.

    2011-06-30

    Polyphenylene sulfide (PPS) is a semicrystalline polymer with excellent engineering plastic properties and suitable processing temperatures. PPS can also be made containing branches (using a trifunctional monomer) and with crosslinked microstructure (when curing the monomer at high temperature in the presence of oxygen). PPS is made from the condensation reaction between para-dichlorobenzene and sodium sulfide with the assistance of a catalyst (to lower the activation barrier). The synthesis conditions for making PPS has evolved since its invention in the 1960's to the optimal conditions developed by the Philips Corporation in the 1970's. The resulting polymer consists of chemically stable molecular moieties such as benzene rings and ether like sulfur linkages between the aromatic rings. Polyphenylene sulfide (PPS) is extremely resistant to gamma irradiation, caustic solution, and dilute nitric acid. PPS is the material of construction for the coalescers used in the Modular Caustic-Side Solvent Extraction Unit (MCU). After applying the equivalent of 3.3 E8 rad (330 Mrad), or the equivalent of 11 years of gamma irradiation (assuming a stripping solution concentration of 7.5 Ci/gal), and several months of exposures to 3M caustic solution and caustic salt simulant, no dimensional changes nor chemical changes were detected in PPS whether the PPS was in fiber form or in a composite with E-glass fibers. However, PPS acts as a media for heterogeneous nucleation. In particular, PPS appears to favor aluminosilicate formation in saturated solutions of aluminum and silicon in caustic environments. Parallel testing, in progress, is examining the stability of PPS when exposed to the new solvent formulation under development for MCU. Preliminary data, after two months of exposure, demonstrates PPS is stable to the new solvent.

  15. Leaching mechanism of zinc powder replacement residue containing gallium and germanium by high pressure acid leaching%锌粉置换镓锗渣高压酸浸的浸出机理

    Institute of Scientific and Technical Information of China (English)

    刘付朋; 刘志宏; 李玉虎; 刘智勇; 李启厚

    2014-01-01

    The high pressure acid leaching of zinc powder replacement residue containing gallium and germanium was carried out. The effects of sulfuric acid concentration, liquid to solid ratio, time, temperature, as well as the kind and concentration of leaching assistant agents on the leaching rates of gallium and germanium were studied, the filterabilities of the leaching residues were also investigated. The results show that increasing sulfuric acid concentration till 156 g/L benefits the leaching of gallium and germanium. Above this point, the leaching rate of germanium will decrease. The increase of leaching time or temperature has little influence on the leaching rates of gallium and germanium, but the filterabilities of leaching residues are improved obviously. Adding cadmium nitrate or sodium nitrate can improve the leaching of gallium and germanium, moreover, adding cadmium nitrate can also improves the filterability of the leaching residue sharply. The sample of zinc powder replacement residues is leached for 3 h under the conditions of sulfuric acid concentration of 156 g/L, cadmium nitrate concentration of 60 g/L as leaching assistant agent, liquid to solid ratio of 8, temperature of 150℃, the leaching rates obtained are over 98% for gallium and over 94% for germanium, respectively. Moreover, the filterability of the leaching residue is 20 times more than that of the residue obtained under normal pressure acid leaching condition.%研究锌粉置换镓锗渣的高压酸浸过程,考察硫酸浓度、液固比、浸出时间、浸出温度、助浸剂种类和添加量对Ga、Ge浸出率以及浸出渣过滤性能的影响。结果表明:增加硫酸浓度有利于Ga、Ge的浸出,但硫酸浓度超过156 g/L后,反而不利于Ge的浸出。浸出时间和温度对Ga、Ge浸出率影响较小,但增加浸出时间或提高反应温度均有利于改善浸出渣的过滤性能。添加硝酸钠或硝酸钙均可促进Ga、Ge

  16. Nitrate leaching from short-hydroperiod floodplain soils

    Directory of Open Access Journals (Sweden)

    B. Huber

    2012-05-01

    Full Text Available Numerous studies have shown the importance of riparian zones to reduce nitrate (NO3 contamination coming from adjacent agricultural land. Much less is known about nitrogen (N transformations and nitrate fluxes in riparian soils with short hydroperiods (1–3 days of inundation and there is no study that could show whether these soils are a N sink or source.

    Within a restored section of the Thur River in NE Switzerland, we measured nitrate concentrations in soil solutions as an indicator of the net nitrate production. Samples were collected along a quasi-successional gradient from frequently inundated gravel bars to an alluvial forest, at three different depths (10, 50 and 100 cm over a one-year period. Along this gradient we quantified N input (atmospheric deposition and sedimentation and N output (leaching to create a nitrogen balance and assess the risk of nitrate leaching from the unsaturated soil to the groundwater.

    Overall, the main factor explaining the differences in nitrate concentrations was the variability in soil texture and volumetric water content (VWC at field capacity (FC. In subsoils with high VWC at FC and VWC near 100 % FC, high nitrate concentrations were observed, often exceeding the Swiss and EU groundwater quality criterions of 400 and 800 μmol l−1, respectively. High sedimentation rates of river-derived nitrogen led to apparent N retention up to 200 kg N ha−1 yr−1 in the frequently inundated zones. By contrast, in the mature alluvial forest, nitrate leaching exceeded total N input most of the time. As a result of the large soil N pools, high amounts of nitrate were produced by nitrification and up to 94 kg N-NO3 ha−1 yr−1 were leached into the groundwater. Thus, during flooding when water fluxes are high, nitrate from soils can contribute up to 11 % to the total nitrate load in groundwater.

  17. Nitrate leaching from short-hydroperiod floodplain soils

    Directory of Open Access Journals (Sweden)

    B. Huber

    2012-11-01

    Full Text Available Numerous studies have shown the importance of riparian zones to reduce nitrate (NO3 contamination coming from adjacent agricultural land. Much less is known about nitrogen (N transformations and nitrate fluxes in riparian soils with short hydroperiods (1–3 days of inundation and there is no study that could show whether these soils are a N sink or source. Within a restored section of the Thur River in NE Switzerland, we measured nitrate concentrations in soil solutions as an indicator of the net nitrate production. Samples were collected along a quasi-successional gradient from frequently inundated gravel bars to an alluvial forest, at three different depths (10, 50 and 100 cm over a one-year period. Along this gradient we quantified N input (atmospheric deposition and sedimentation and N output (leaching to create a nitrogen balance and assess the risk of nitrate leaching from the unsaturated soil to the groundwater. Overall, the main factor explaining the differences in nitrate concentrations was the field capacity (FC. In subsoils with high FCs and VWC near FC, high nitrate concentrations were observed, often exceeding the Swiss and EU groundwater quality criterions of 400 and 800 μmol L−1, respectively. High sedimentation rates of river-derived nitrogen led to apparent N retention up to 200 kg N ha−1 yr−1 in the frequently inundated zones. By contrast, in the mature alluvial forest, nitrate leaching exceeded total N input most of the time. As a result of the large soil N pools, high amounts of nitrate were produced by nitrification and up to 94 kg N-NO3 ha−1 yr−1 were leached into the groundwater. Thus, during flooding when water fluxes are high, nitrate from soils can contribute up to 11% to the total nitrate load in groundwater.

  18. Leaching of metals from steel samples in peracetic acid

    Science.gov (United States)

    Yabutani, Tomoki; Nakamura, Takamasa; Takayabagi, Toshio

    2015-03-01

    In this paper, leaching behavior of metallic species from steel samples in peracetic acid was investigated. We compared the leaching efficiency between peracetic acid and acetic acid to estimate the role of peroxo functional group for the leaching. As a result, peracetic acid enhanced the leaching ability of metallic species from the high speed steel and the alloy steel samples. MoO3, Mo, MO2C, W, WO3, VC and MnO2 were effectively leached by peracetic acid, while the stainless steel had a high resistance against corrosion by peracetic acid.

  19. SPR salt wall leaching experiments in lab-scale vessel : data report.

    Energy Technology Data Exchange (ETDEWEB)

    Webb, Stephen Walter; O' Hern, Timothy John; Hartenberger, Joel David

    2010-10-01

    During cavern leaching in the Strategic Petroleum Reserve (SPR), injected raw water mixes with resident brine and eventually interacts with the cavern salt walls. This report provides a record of data acquired during a series of experiments designed to measure the leaching rate of salt walls in a labscale simulated cavern, as well as discussion of the data. These results should be of value to validate computational fluid dynamics (CFD) models used to simulate leaching applications. Three experiments were run in the transparent 89-cm (35-inch) ID diameter vessel previously used for several related projects. Diagnostics included tracking the salt wall dissolution rate using ultrasonics, an underwater camera to view pre-installed markers, and pre- and post-test weighing and measuring salt blocks that comprise the walls. In addition, profiles of the local brine/water conductivity and temperature were acquired at three locations by traversing conductivity probes to map out the mixing of injected raw water with the surrounding brine. The data are generally as expected, with stronger dissolution when the salt walls were exposed to water with lower salt saturation, and overall reasonable wall shape profiles. However, there are significant block-to-block variations, even between neighboring salt blocks, so the averaged data are considered more useful for model validation. The remedial leach tests clearly showed that less mixing and longer exposure time to unsaturated water led to higher levels of salt wall dissolution. The data for all three tests showed a dividing line between upper and lower regions, roughly above and below the fresh water injection point, with higher salt wall dissolution in all cases, and stronger (for remedial leach cases) or weaker (for standard leach configuration) concentration gradients above the dividing line.

  20. Recovery of iron from cyanide tailings with reduction roasting-water leaching followed by magnetic separation

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Yali; Li, Huaimei [College of Chemical Engineering, Shandong University of Technology, 255081, Zibo, Shandong (China); Yu, Xianjin, E-mail: xjy@sdut.edu.cn [College of Chemical Engineering, Shandong University of Technology, 255081, Zibo, Shandong (China)

    2012-04-30

    Highlights: Black-Right-Pointing-Pointer Using reduction roasting-water leaching-magnetic separation method, the recovery of iron from cyanide tailings was optimized. Black-Right-Pointing-Pointer The recovery of iron was highly depended on the water-leaching process after reduction roasting. Black-Right-Pointing-Pointer The results suggest that the method can be effectively used for iron recovery, and the grade of magnetic concentrate and recovery rate can reach 59.11% and 75.12%, respectively. - Abstract: Cyanide tailing is a kind of solid waste produced in the process of gold extraction from gold ore. In this paper, recovery of iron from cyanide tailings was studied with reduction roasting-water leaching process followed by magnetic separation. After analysis of chemical composition and crystalline phase, the effects of different parameters on recovery of iron were chiefly introduced. Systematic studies indicate that the high recovery rate and grade of magnetic concentrate of iron can be achieved under the following conditions: weight ratios of cyanide tailings/activated carbon/sodium carbonate/sodium sulfate, 100:10:3:10; temperature, 50 Degree-Sign C; time, 60 min at the reduction roasting stage; the liquid to solid ratio is 15:1 (ml/g), leaching at 60 Degree-Sign C for 5 min and stirring speed at 20 r/min at water-leaching; exciting current is 2 A at magnetic separation. The iron grade of magnetic concentrate was 59.11% and the recovery ratio was 75.12%. The mineralography of cyanide tailings, roasted product, water-leached sample, magnetic concentrate and magnetic tailings were studied by X-ray powder diffraction (XRD) technique. The microstructures of above products except magnetic tailings were also analyzed by scanning electron microscope (SEM) and energy disperse spectroscopy (EDS) to help understand the mechanism.

  1. A simple approach to identify critical source areas for phosphorus leaching in the Netherlands

    Science.gov (United States)

    van der Salm, C.; Schoumans, O. F.; Walvoort, D.; Groenendijk, P.; Pleijter, M.

    2009-04-01

    High soil phopshorus contents in agricultural soils in the Netherlands cause excessive losses of P to surface waters. The reductions in P application rates in the present manure policy are not sufficient to reach surface water quality standards resulting from the European Water Framework Directive in all catchments by 2015. Accordingly, additional measures have to be considered to further reduce P loading to surface water. For a cost effective implementation of these measures an instrument to identify critical source areas for phosphorus leaching is indispensable. In the Netherlands phosphorus leaching at a national scale is simulated with a comprehensive mechanistic simulation model (STONE, Wolf et al., 2005) focusing on changes in P leaching with time. The identification of critical source areas requires simulations at a high spatial resolution. STONE is less suitable for this purpose, because of the large number of input parameters required by this complex model. For this reason, a simple model (PLEASE: Phosphorus LEAching from Soils to the Environment; Schoumans et al., in prep.) has been developed based on the same mechanistic process description for inorganic P as the complex model STONE and a simplified description of the lateral flow of water from soil to surface waters. With this model P leaching to surface waters can be calculated using readily available information of field characteristics like depth of the groundwater table, precipitation surplus and P status and phosphorus adsorption capacity of the soil. To evaluate the performance of the model, it was applied to the Netherlands using the same input as the national model. Parameterised in this way, PLEASE is a metamodel of STONE. The model was also tested on two small catchments: a catchment with sandy soils and high P accumulation and a clay catchment with a moderate P accumulation. The application at the national scale showed that the overall order of magnitude of the calculated leaching fluxes was

  2. Standard test method for accelerated leach test for diffusive releases from solidified waste and a computer program to model diffusive, fractional leaching from cylindrical waste forms

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2008-01-01

    1.1 This test method provides procedures for measuring the leach rates of elements from a solidified matrix material, determining if the releases are controlled by mass diffusion, computing values of diffusion constants based on models, and verifying projected long-term diffusive releases. This test method is applicable to any material that does not degrade or deform during the test. 1.1.1 If mass diffusion is the dominant step in the leaching mechanism, then the results of this test can be used to calculate diffusion coefficients using mathematical diffusion models. A computer program developed for that purpose is available as a companion to this test method (Note 1). 1.1.2 It should be verified that leaching is controlled by diffusion by a means other than analysis of the leach test solution data. Analysis of concentration profiles of species of interest near the surface of the solid waste form after the test is recommended for this purpose. 1.1.3 Potential effects of partitioning on the test results can...

  3. Mechanochemical leaching of chalcopyrite concentrate by sulfuric acid

    Institute of Scientific and Technical Information of China (English)

    Sina Hejazi; Jalil Vahdati khaki; Abolfazl Babakhani

    2016-01-01

    This study aimed to introduce a new cost-effective methodology for increasing the leaching efficiency of chalcopyrite concentrates at ambient temperature and pressure. Mechanical activation was employed during the leaching (mechanochemical leaching) of chalcopyrite concentrates in a sulfuric acid medium at room temperature and atmospheric pressure. High energy ball milling process was used during the leaching to provide the mechanochemical leaching condition, and atomic absorption spectroscopy and cyclic voltammetry were used to de-termine the leaching behavior of chalcopyrite. Moreover, X-ray diffraction and scanning electron microscopy were used to characterize the chalcopyrite powder before and after leaching. The results demonstrated that mechanochemical leaching was effective; the extraction of copper increased significantly and continuously. Although the leaching efficiency of chalcopyrite was very low at ambient temperature, the percentages of copper dissolved in the presence of hydrogen peroxide (H2O2) and ferric sulfate (Fe2(SO4)3) after 20 h of mechanochemical leaching reached 28%and 33%, respectively. Given the efficiency of the developed method and the facts that it does not require the use of an autoclave and can be conducted at room temperature and atmospheric pressure, it represents an economical and easy-to-use method for the leaching industry.

  4. Predictive Factors of Gastrointestinal Caustic Injury According to Clinical and Endoscopic Findings

    Directory of Open Access Journals (Sweden)

    Cherie Quingking

    2013-03-01

    Full Text Available Background: Ingestion of caustic substances is the main reason for referral to Philippines National Poison Management and Control Center among other causes of acute poisoning. Rapid assessment of severity of injury is important for treatment and prognosis of these cases. This study was aimed to investigate the correlation of clinical factors with severity of gastrointestinal (GI mucosal injury. Methods: In this retrospective study, a total of 105 patients were included. Patients were categorized into two groups including 35 patients with low grade and 70 patients with high grade GI injury to compare the predictive value of clinical findings. Results: Mean (SD age of patients was 27 (10 and 47% of patients were male. Oral burns (P

  5. Probe of Multi-electron Dynamics in Xenon by Caustics in High Order Harmonic Generation

    CERN Document Server

    Faccialà, Davide; Bruner, Barry D; Ciriolo, Anna G; De Silvestri, Sandro; Devetta, Michele; Negro, Matteo; Soifer, Hadas; Stagira, Salvatore; Dudovich, Nirit; Vozzi, Caterina

    2016-01-01

    We investigated the giant resonance in Xenon by high-order harmonic generation spectroscopy driven by a two-color field. The addition of a non-perturbative second harmonic component parallel to the driving field breaks the symmetry between neighboring sub-cycles resulting in the appearance of spectral caustics at two distinct cut-off energies. By controlling the phase delay between the two color components it is possible to tailor the harmonic emission in order to amplify and isolate the spectral feature of interest. In this paper we demonstrate how this control scheme can be used to investigate the role of electron correlations that give birth to the giant resonance in Xenon. The collective excitations of the giant dipole resonance in Xenon combined with the spectral manipulation associated with the two color driving field allow to see features that are normally not accessible and to obtain a quantitative good agreement between the experimental results and the theoretical predictions.

  6. Effect of solvent addition sequence on lycopene extraction efficiency from membrane neutralized caustic peeled tomato waste.

    Science.gov (United States)

    Phinney, David M; Frelka, John C; Cooperstone, Jessica L; Schwartz, Steven J; Heldman, Dennis R

    2017-01-15

    Lycopene is a high value nutraceutical and its isolation from waste streams is often desirable to maximize profits. This research investigated solvent addition order and composition on lycopene extraction efficiency from a commercial tomato waste stream (pH 12.5, solids ∼5%) that was neutralized using membrane filtration. Constant volume dilution (CVD) was used to desalinate the caustic salt to neutralize the waste. Acetone, ethanol and hexane were used as direct or blended additions. Extraction efficiency was defined as the amount of lycopene extracted divided by the total lycopene in the sample. The CVD operation reduced the active alkali of the waste from 0.66 to Extraction efficiency varied from 32.5% to 94.5%. This study demonstrates a lab scale feasibility to extract lycopene efficiently from tomato processing byproducts. PMID:27542486

  7. The Caustic Alkali-free Water Extraction Agents for Treating Inner Mongolia Oil Sands

    Institute of Scientific and Technical Information of China (English)

    Shen Zhibing; Zhang Juntao; Zhang Jie; Liang Shengrong

    2014-01-01

    The caustic alkali-free water extraction agents were studied for treating the oil sands excavated from Inner Mon-golia, China. Several kinds of chemical reagents were evaluated, among which sodium carbonate (SC), sodium dodecyl benzene sulfonate (SD) and sodium chloride were conifrmed as composite solutes. Their proportion was optimized by an orthogonal test. The optimum proportion of the composite agent covered 0.03%of SD, 0.50%of sodium chloride, 3.00%of SC, with the rest composed of water. The optimal operating condition was also conifrmed. The oil sands were extracted at the following optimized conditions:a treating time of 15 min, a temperature of 80℃and an extraction agent/feed ratio of 1:1, with the bitumen yield reaching more than 96%. The extraction agent after separation from the bitumen product can be recycled for reuse to carve out a good environmentally friendly route.

  8. Removal of phosphorus from iron ores by chemical leaching

    Institute of Scientific and Technical Information of China (English)

    JIN Yong-shi; JIANG Tao; YANG Yong-bin; LI Qian; LI Guang-hui; GUO Yu-feng

    2006-01-01

    Alkali-leaching and acid-leaching were proposed for the dephosphorization of Changde iron ore, which contains an average of 1.12% for phosphorus content. Sodium hydroxide, sulfuriced, hydrochloric and nitric acids were used for the preparation of leach solutions. The results show that phosphorus occurring as apatite phase could be removed by alkali-leaching, but those occurring in the iron phase could not. Sulfuric acid is the most effective among the three kinds of acid. 91.61% phosphorus removal was attained with 1% sulfuric acid after leaching for 20 min at room temperature. Iron loss during acid-leaching can be negligible, which was less than 0.25%.The pH value of solution after leaching with 1% sulfuric acid was about 0.86, which means acid would not be exhausted during the process and it could be recycled, and the recycle of sulfuric acid solution would make the dephosphorization process more economical.

  9. Use of leaching chambers for on-site sewage treatment.

    Science.gov (United States)

    St Marseille, J G; Anderson, B C

    2002-03-01

    An innovative chamber system was installed for on-site sewage treatment beneath an active parking lot at a restaurant near Cornwall, Ontario. The configuration of this prototype system used polyethylene leaching chambers over which wastewater was allowed to trickle. The chambers were vented to the surface to provide direct, passive air transfer. This demonstration project was examined as a cost-effective wastewater treatment alternative for a very constrained site. The leaching chambers were installed over a geotextile-covered sand filter bed. Chamber sidewall contact contributed an additional 50% to the total soil contact area hence justification for a footprint reduction. A labile carbon source (sawdust) was added into one half of the bed to encourage dissimilatory denitrification. Average hydraulic loading was 50 l m(-1) day(-1) (5 cm day(-1)). Treatment rates exceeded more than 4 orders of magnitude removal for E. coli; 90% biochemical oxygen demand; ammonium; and 99% total phosphorus. Nitrate-N on the carbon-amended side averaged 0.6 mg l(-1) compared with 8.6 mg l(-1) on the (non-carbon) control side. This project has demonstrated that effective on-site treatment can be accomplished. Flow and load equalization, pulse dosing, chamber venting, phosphorus precipitation, and denitrification were keys to treatment success. Applications include domestic and commercial sites. PMID:11999988

  10. Ecological plasticity of Trichoderma fungi in leached chernozem

    Science.gov (United States)

    Svistova, I. D.; Senchakova, T. Yu.

    2010-03-01

    The autecological properties of Trichoderma fungi ecotypes isolated from the leached chernozem of the forest-steppe zone of the European part of Russia have been studied. We were the first who carried out the complex study of the synecological relations of micromycetes of such kinds in a system including the soil, microbial community, and plants, i.e., their relations with soil saprotrophic fungi, bacteria, actinomycetes, plants, and pathogenic fungi. It was shown that the ecological plasticity of the Trichoderma genus in the soil of this zone is determined by its growth rate, the optimum pH and temperature, the biosynthesis of extracellular hydrolytic enzymes, the biological action of mycotoxins, and the ability for parasitism. The efficiency of the introduction of Trichoderma species typical and atypical for the leached chernozem into this soil and their influence on the structure of the microbial community were evaluated. The T. pseudokoningii ecotype, which produces cellulolytic enzymes, is very promising for industrial biotechnology, and the T. harzianum ecotype can be used in soil biotechnology for the biocontrol of chernozem. The addition of a commercial trichodermin preparation into the chernozem damages the structure of its microbial community.

  11. Evolution of the local environment of lanthanum during simplified SON68 glass leaching

    Energy Technology Data Exchange (ETDEWEB)

    Jollivet, P.; Delaye, J.M. [CEA, Lab Comportement Long Terme, F-30207 Bagnols Sur Ceze (France); Den Auwer, C. [CEA, Lab Concept Architectures Mol, F-30207 Bagnols Sur Ceze (France); Simoni, E. [Inst Phys Nucl, F-91406 Orsay (France)

    2007-03-15

    The evolution of the short- and medium-range local environment of lanthanum was determined by L-III-edge X-ray absorption spectroscopy (XAS) during leaching of simplified SON68-type glasses. In glass without phosphorus, lanthanum is found in a silicate environment, and its first coordination sphere comprises eight oxygen atoms at a mean distance of 2.51 angstrom. When this glass was leached at a high renewal rate, the lanthanum local environment was significantly modified: it was present at hydroxy-carbonate and silicate sites with a mean La-O distance of 2.56 angstrom, and the second neighbors consisted of La atoms instead of Si for the glass. Conversely, in the gel formed at low renewal rates, lanthanum was found in a silicate environment similar to that of the glass. In phosphorus-doped glass, lanthanum is found in a phosphate environment, although the Si/P atomic ratio is 20:1. Lanthanum is surrounded by seven oxygen atoms at a mean distance of 2.37 angstrom. When phosphorus-doped glass is leached, regardless of the leaching solution flow rate, the short- and medium-range lanthanum local environment remains almost constant; the most significant change is a 0.05 angstrom increase in the La-O distance. (authors)

  12. Evolution of the local environment of lanthanum during simplified SON68 glass leaching

    International Nuclear Information System (INIS)

    The evolution of the short- and medium-range local environment of lanthanum was determined by L-III-edge X-ray absorption spectroscopy (XAS) during leaching of simplified SON68-type glasses. In glass without phosphorus, lanthanum is found in a silicate environment, and its first coordination sphere comprises eight oxygen atoms at a mean distance of 2.51 angstrom. When this glass was leached at a high renewal rate, the lanthanum local environment was significantly modified: it was present at hydroxy-carbonate and silicate sites with a mean La-O distance of 2.56 angstrom, and the second neighbors consisted of La atoms instead of Si for the glass. Conversely, in the gel formed at low renewal rates, lanthanum was found in a silicate environment similar to that of the glass. In phosphorus-doped glass, lanthanum is found in a phosphate environment, although the Si/P atomic ratio is 20:1. Lanthanum is surrounded by seven oxygen atoms at a mean distance of 2.37 angstrom. When phosphorus-doped glass is leached, regardless of the leaching solution flow rate, the short- and medium-range lanthanum local environment remains almost constant; the most significant change is a 0.05 angstrom increase in the La-O distance. (authors)

  13. Field-scale leaching of arsenic, chromium and copper from weathered treated wood

    Energy Technology Data Exchange (ETDEWEB)

    Hasan, A. Rasem, E-mail: hasan@arij.or [Department of Civil, Architectural and Environmental Engineering, University of Miami, 1251 Memorial Dr., Coral Gables, FL 33124 (United States); Hu Ligang [Department of Chemistry and Biochemistry, Florida International University, 11200 SW 8th Street, University Park, Miami, FL 33199 (United States); Solo-Gabriele, Helena M., E-mail: hmsolo@miami.ed [Department of Civil, Architectural and Environmental Engineering, University of Miami, 1251 Memorial Dr., Coral Gables, FL 33124 (United States); Fieber, Lynne [Division of Marine Biology and Fisheries, Rosenstiel School of Marine and Atmospheric Science, University of Miami, 4600 Rickenbacker Causeway, Miami, FL 33149-1098 (United States); Cai Yong [Department of Chemistry and Biochemistry, Florida International University, 11200 SW 8th Street, University Park, Miami, FL 33199 (United States); Southeast Environmental Research Center, Florida International University, 11200 SW 8th Street, University Park, Miami, FL 33199 (United States); Townsend, Timothy G. [Department of Environmental Engineering Sciences, University of Florida, 217 A.P. Black Hall, Gainesville, FL 32611-6450 (United States)

    2010-05-15

    Earlier studies documented the loss of wood preservatives from new wood. The objective of this study was to evaluate losses from weathered treated wood under field conditions by collecting rainfall leachate from 5 different wood types, all with a surface area of 0.21 m{sup 2}. Wood samples included weathered chromate copper arsenate (CCA) treated wood at low (2.7 kg/m{sup 3}), medium (4.8 kg/m{sup 3}) and high (35.4 kg/m{sup 3}) retention levels, new alkaline copper quat (ACQ) treated wood (1.1 kg/m{sup 3} as CuO) and new untreated wood. Arsenic was found to leach at a higher rate (100 mg in 1 year for low retention) than chromium and copper (<40 mg) in all CCA-treated wood samples. Copper leached at the highest rate from the ACQ sample (670 mg). Overall results suggest that metals' leaching is a continuous process driven by rainfall, and that the mechanism of release from the wood matrix changes as wood weathers. - Metals leaching rates on a percent basis increase as treated wood weathers, although the mass released decreases.

  14. Next Generation Solvent (NGS): Development for Caustic-Side Solvent Extraction of Cesium

    International Nuclear Information System (INIS)

    This report summarizes the FY 2010 and 2011 accomplishments at Oak Ridge National Laboratory (ORNL) in developing the Next Generation Caustic-Side Solvent Extraction (NG-CSSX) process, referred to commonly as the Next Generation Solvent (NGS), under funding from the U.S. Department of Energy, Office of Environmental Management (DOE-EM), Office of Technology Innovation and Development. The primary product of this effort is a process solvent and preliminary flowsheet capable of meeting a target decontamination factor (DF) of 40,000 for worst-case Savannah River Site (SRS) waste with a concentration factor of 15 or higher in the 18-stage equipment configuration of the SRS Modular Caustic-Side Solvent Extraction Unit (MCU). In addition, the NG-CSSX process may be readily adapted for use in the SRS Salt Waste Processing Facility (SWPF) or in supplemental tank-waste treatment at Hanford upon appropriate solvent or flowsheet modifications. Efforts in FY 2010 focused on developing a solvent composition and process flowsheet for MCU implementation. In FY 2011 accomplishments at ORNL involved a wide array of chemical-development activities and testing up through single-stage hydraulic and mass-transfer tests in 5-cm centrifugal contactors. Under subcontract from ORNL, Argonne National Laboratory (ANL) designed a preliminary flowsheet using ORNL cesium distribution data, and Tennessee Technological University confirmed a chemical model for cesium distribution ratios (DCs) as a function of feed composition. Interlaboratory efforts were coordinated with complementary engineering tests carried out (and reported separately) by personnel at Savannah River National Laboratory (SRNL) and Savannah River Remediation (SRR) with helpful advice by Parsons Engineering and General Atomics on aspects of possible SWPF implementation.

  15. Next Generation Solvent Performance in the Modular Caustic Side Solvent Extraction Process - 15495

    Energy Technology Data Exchange (ETDEWEB)

    Smith, Tara E. [Savannah River Remediation, LLC., Aiken, SC (United States); Scherman, Carl [Savannah River Remediation, LLC., Aiken, SC (United States); Martin, David [Savannah River Remediation, LLC., Aiken, SC (United States); Suggs, Patricia [Savannah River Site (SRS), Aiken, SC (United States)

    2015-01-14

    Changes to the Modular Caustic Side Solvent Extraction Unit (MCU) flow-sheet were implemented in the facility. Implementation included changing the scrub and strip chemicals and concentrations, modifying the O/A ratios for the strip, scrub, and extraction contactor banks, and blending the current BoBCalixC6 extractant-based solvent in MCU with clean MaxCalix extractant-based solvent. During the successful demonstration period, the MCU process was subject to rigorous oversight to ensure hydraulic stability and chemical/radionuclide analysis of the key process tanks (caustic wash tank, solvent hold tank, strip effluent hold tank, and decontaminated salt solution hold tank) to evaluate solvent carryover to downstream facilities and the effectiveness of cesium removal from the liquid salt waste. Results indicated the extraction of cesium was significantly more effective with an average Decontamination Factor (DF) of 1,129 (range was 107 to 1,824) and that stripping was effective. The contactor hydraulic performance was stable and satisfactory, as indicated by contactor vibration, contactor rotational speed, and flow stability; all of which remained at or near target values. Furthermore, the Solvent Hold Tank (SHT) level and specific gravity was as expected, indicating that solvent integrity and organic hydraulic stability were maintained. The coalescer performances were in the range of processing results under the BOBCalixC6 flow sheet, indicating negligible adverse impact of NGS deployment. After the Demonstration period, MCU began processing via routine operations. Results to date reiterate the enhanced cesium extraction and stripping capability of the Next Generation Solvent (NGS) flow sheet. This paper presents process performance results of the NGS Demonstration and continued operations of MCU utilizing the blended BobCalixC6-MaxCalix solvent under the NGS flowsheet.

  16. Synthesis of ZnS thin films from aqueous caustic of trisodium citrate and their properties

    Directory of Open Access Journals (Sweden)

    Martyn A. Sozanskyi

    2015-12-01

    Full Text Available Zinc sulfide (ZnS thin films due to their properties are widely used in various electronic optical devices. They are produced by several methods, among which – vacuum sublimation, high frequency sputtering method, quasiclosed volume method, sol-gel method, electrodeposition. These methods have high energy consumption which increases the price of ZnS thin films. Aim: The aim of this work is to establish the optimal parameters of the synthesis of ZnS thin films of the aqueous caustic and the correlation between content of zinc in the synthesized films determined by the method of stripping voltammetry and thickness, structural, morphological and optical parameters. Materials and Methods: The ZnS thin films were obtained from aqueous caustics of zinc-containing salt using chemical deposition. Fresh solution of zinc-containing salt, trisodium citrate (Na3C6H5O7 as a complexing agent, thiourea ((NH22CS and ammonium hydroxide (NH4OH was used for the synthesis of ZnS films by chemical deposition. The deposition was performed on prepared glass substrates with the area of 5,76 cm2. Results: The phase mixture of the films has been determined. It showed the presence of ZnS compounds in the cubic modification (sphalerite. Stripping voltammetry was used to determine the mass of zinc in the ZnS films on various conditions of synthesis, namely on the concentration of the initial zinc-containing salt, trisodium citrate, thiourea, deposition time and temperature. The surface morphology, optical properties, the thickness of the ZnS resulting films have been studied. Conclusions: The optimal conditions for the synthesis of ZnS films were found based on these data. Three-dimensional surface morphology of ZnS film studies showed its smoothness, uniformity, integrity and confirmed the correctness of determining the optimal synthesis parameters.

  17. Next Generation Solvent Development for Caustic-Side Solvent Extraction of Cesium

    Energy Technology Data Exchange (ETDEWEB)

    Moyer, Bruce A. [Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States); Birdwell, Joseph F. [Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States); Bonnesen, Peter V. [Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States); Bruffey, Stephanie [Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)

    2014-03-01

    This report summarizes the FY 2010 and 2011 accomplishments at Oak Ridge National Laboratory (ORNL) in developing the Next Generation Caustic-Side Solvent Extraction (NG-CSSX) process, referred to commonly as the Next Generation Solvent (NGS), under funding from the U.S. Department of Energy, Office of Environmental Management (DOE-EM), Office of Technology Innovation and Development. The primary product of this effort is a process solvent and preliminary flowsheet capable of meeting a target decontamination factor (DF) of 40,000 for worst-case Savannah River Site (SRS) waste with a concentration factor of 15 or higher in the 18-stage equipment configuration of the SRS Modular Caustic-Side Solvent Extraction Unit (MCU). In addition, the NG-CSSX process may be readily adapted for use in the SRS Salt Waste Processing Facility (SWPF) or in supplemental tank-waste treatment at Hanford upon appropriate solvent or flowsheet modifications. Efforts in FY 2010 focused on developing a solvent composition and process flowsheet for MCU implementation. In FY 2011 accomplishments at ORNL involved a wide array of chemical-development activities and testing up through single-stage hydraulic and mass-transfer tests in 5-cm centrifugal contactors. Under subcontract from ORNL, Argonne National Laboratory (ANL) designed a preliminary flowsheet using ORNL cesium distribution data, and Tennessee Technological University confirmed a chemical model for cesium distribution ratios (DCs) as a function of feed composition. Inter laboratory efforts were coordinated with complementary engineering tests carried out (and reported separately) by personnel at Savannah River National Laboratory (SRNL) and Savannah River Remediation (SRR) with helpful advice by Parsons Engineering and General Atomics on aspects of possible SWPF implementation.

  18. Next Generation Solvent (NGS): Development for Caustic-Side Solvent Extraction of Cesium

    Energy Technology Data Exchange (ETDEWEB)

    Moyer, Bruce A. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Birdwell, Jr, Joseph F. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Bonnesen, Peter V. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Bruffey, Stephanie H. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Delmau, Laetitia Helene [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Duncan, Nathan C. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Ensor, Dale [Tennessee Technological Univ., Cookeville, TN (United States); Hill, Talon G. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Lee, Denise L. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Rajbanshi, Arbin [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Roach, Benjamin D. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Szczygiel, Patricia L. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Sloop, Jr., Frederick V. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Stoner, Erica L. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Williams, Neil J. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2014-03-01

    This report summarizes the FY 2010 and 2011 accomplishments at Oak Ridge National Laboratory (ORNL) in developing the Next Generation Caustic-Side Solvent Extraction (NG-CSSX) process, referred to commonly as the Next Generation Solvent (NGS), under funding from the U.S. Department of Energy, Office of Environmental Management (DOE-EM), Office of Technology Innovation and Development. The primary product of this effort is a process solvent and preliminary flowsheet capable of meeting a target decontamination factor (DF) of 40,000 for worst-case Savannah River Site (SRS) waste with a concentration factor of 15 or higher in the 18-stage equipment configuration of the SRS Modular Caustic-Side Solvent Extraction Unit (MCU). In addition, the NG-CSSX process may be readily adapted for use in the SRS Salt Waste Processing Facility (SWPF) or in supplemental tank-waste treatment at Hanford upon appropriate solvent or flowsheet modifications. Efforts in FY 2010 focused on developing a solvent composition and process flowsheet for MCU implementation. In FY 2011 accomplishments at ORNL involved a wide array of chemical-development activities and testing up through single-stage hydraulic and mass-transfer tests in 5-cm centrifugal contactors. Under subcontract from ORNL, Argonne National Laboratory (ANL) designed a preliminary flowsheet using ORNL cesium distribution data, and Tennessee Technological University confirmed a chemical model for cesium distribution ratios (DCs) as a function of feed composition. Interlaboratory efforts were coordinated with complementary engineering tests carried out (and reported separately) by personnel at Savannah River National Laboratory (SRNL) and Savannah River Remediation (SRR) with helpful advice by Parsons Engineering and General Atomics on aspects of possible SWPF implementation.

  19. Leaching of Electronic Waste Using Biometabolised Acids

    Institute of Scientific and Technical Information of China (English)

    M. Saidan; B. Brown; M. Valix

    2012-01-01

    The revolution in information and communication technology has brought huge technical benefits and wealth, but has created a major global problem: the generation of vast amounts of electronic waste, or e-waste through product obsolesce. The challenge in managing e-waste will be in developing sustainable recycling tech- nologies that are able to address the volume and complexity of this waste using cost effective and ecologically sen-sitive methods. In this study, the capability or microorganism metabolic acids in dissolving the metallic tractions from waste printed circuit boards was examined. Several factors were considered in the examination of the activityof the acids-including secondary reactions, solution pH, temperature and the nature of ligands in solutions (or bioacid constituents). The leaching tests were cgnducted ex-situ, using synthetic organic acids. Leaching was performed for periods of up to 6 hat 70-90 ℃ and 1000 r-min-1.

  20. Lead sulphate leaching by sodium chloride solution

    Directory of Open Access Journals (Sweden)

    Conić Vesna T.

    2013-01-01

    Full Text Available Bioleaching treatment of complex multi-metallic Cu-Zn-Pb-Ag-Au mineral concentrates leds to the formation, besides easily soluble zinc and cooper sulphates, of hardly soluble lead (II sulfate (PbSO4 sludge. To determine the leaching parameters of PbSO4 with NaCl in the bioleaching residue, lead sulphate solution was synthetically prepared. The effect of process parameters, namely NaCl concentration, solid:liquid phase ratio, processing time, temperature and Cl ions was examined. It was found that 100% Pb by leaching can be achieved with NaCl concentration of 250 g/dm3, time 20 min, temperature 353 K and solid:liquid phase ratio =1:20.

  1. The equilibrium leach testing of CAGR hulls

    International Nuclear Information System (INIS)

    Equilibrium leach tests were carried out on a laboratory scale in order to investigate the long-term performance of an intermediate level waste repository. The tests involved leaching fully active Commercial Advanced Gas-cooled Reactor (CAGR) hulls in the presence of crushed matrix and backfill materials. The matrix materials used were blast furnace slag (BFS)/ordinary Portland cement (OPC) and epoxide MS7531/MS7532, and the backfill materials were bentonite and pulverised fuel ash/ordinary Portland cement (PFA/OPC). Comparison of the long-lived radionuclide concentrations with the derived drinking water levels indicates that the performance of a repository under oxidising conditions would tend to be limited by the release of I-129 and Tc-99. (author)

  2. Leaching from denture base materials in vitro

    Energy Technology Data Exchange (ETDEWEB)

    Lygre, H.; Solheim, E.; Gjerdet, N.R. [School of Medicine, Univ. of Bergen (Norway)

    1995-04-01

    Specimens made from denture base materials were leached in Ringer Solution and in ethanol. The specimens comprised a heat-cured product processed in two different ways and two cold-cured materials. The organic compounds leaching from the specimens to the solutions were separated, identified, and quantified by a combined gas-chromatography and gas-chromatography/mass-spectrometry technique. Additives and degradation products, possibly made by free radical reactions, were released from the denture base materials. In Ringer solution only phthalates could be quantified. In ethanol solvent, biphenyl, dibutyl phthalate, dicyclohexyl phthalate, phenyl benzoate, and phenyl salicylate were quantified. In addition, copper was found in the ethanol solvent from one of the denture base materials. The amount of leachable organic compounds varies among different materials. Processing temperature influences the initial amount of leachable compounds. 36 refs., 7 figs., 1 tab.

  3. Nitrate leaching of winter wheat grown in lysimeters as affected by fertilizers and irrigation on the North China Plain

    Institute of Scientific and Technical Information of China (English)

    GU Li-min; LIU Tie-ning; ZHAO Jun; DONG Shu-ting; LIU Peng; ZHANG Ji-wang; ZHAO Bin

    2015-01-01

    Proper application of nitrogen (N) fertilizers and irrigation management are important production practices that can reduce nitrate leaching into groundwater and improve the N use efifciency (NUE). A lysimeter/rain shelter facility was used to study effects of the rate of N fertilization, type of N fertilizer, and irrigation level on key aspects of winter wheat production over three growing seasons (response variables were nitrate transport, N leaching, and NUE). Results indicated that nitrate concentration in the soil proifle and N leaching increased with the rate of N fertilization. At the end of the third season, nitrate concentration in the top 0–75 cm layer of soil was higher with manure treatment while urea treatments resulted in higher concentrations in the 100–200 cm layer. With normal irrigation, 3.4 to 15.3%of N from applied fertilizer was leached from the soil, yet no leaching occurred under a stress irrigation treatment. The manure treatment experienced less N leaching than the urea treatment in al cases except for the 180 kg N ha-1 rate in 2011–2012 (season 3). In terms of grain yield (GY), dry matter (DM) or NUE parameters, values for the manure treatment were lower than for the urea treatment in 2009–2010 (season 1), yet were otherwise higher for urea treatment in season 3. GY and crop nitrogen uptake (NU) were elevated when the rate of N fertilizer increased, while the NUE decreased;GY, DM, and NU increased with the amount of irrigation. Data indicated that reduced rates of N fertilization combined with increased manure application and proper irrigation management can lower nitrate levels in the subsoil and reduce potential N leaching into groundwater.

  4. Gold and Silver Extraction from Leach Solutions

    Directory of Open Access Journals (Sweden)

    Bagdaulet K. Kenzhaliyev

    2014-03-01

    Full Text Available There has been carried out an investigation on the extraction of gold and silver from thiosulfate solutions: standard test and technological solutions of chemical and electrochemical leaching. The influence of related metals on the process of extracting gold from solution was studied. There has been conducted a comparative study of the IR spectra of solutions after the sorption of gold, silver and related metals.

  5. Alkaline leaching of iron and steelmaking dust

    OpenAIRE

    Stafanova, Anna; Aromaa, Jari

    2012-01-01

    Steel production generates significant quantities of dust and sludge in blast furnaces (BF),basic oxygen furnaces (BOF), and electric arc furnaces (EAF). These dusts contain toxicelements, such as heavy metals, and are thus classified as harmful waste making the disposalof them expensive. In addition, direct recycling of dust back to steel production is hindered dueto the presence of zinc. In this literature survey the alkaline leaching of zinc from iron and steelmaking dusts isreviewed. T...

  6. Economic leaching at Roessing Uranium Limited

    International Nuclear Information System (INIS)

    In the fourteen years that Roessing Uranium Limited has been in production, the metallurgical operations and controls on the leaching plant have envolved through four basic stages. Initially, the emphasis was placed on the achievement of consistent plant operation by overcoming severe start-up difficulties. The second stage involved the attainment of the design operating targets and also the commissioning of the ferric-leaching reactors in order to achieve a ferric ion concentration of more than 3.0 g/l. Improvements in control then became the priority, with the emphasis on consistently achieving the target concentrations of ferric ions, total iron, and terminal acidity. The latest phase has concentrated on the optimization of costs by means of adjustments to the historically established operating parameters in order to achieve large savings on consumables while maintaining the leaching efficiencies. Apart from the obvious incentive of reducing costs in an inflationary economy and a depressed uranium market, impetus for this work was given by a change in the type of ore from the open pit, which has the effect of reducing the extraction efficiency while increasing the consumption of consumable materials. These problems and their solutions are discussed in detail, and the importance to cost-effective optimization of an accurate up-to-date cost-reporting structure is stressed. 9 figs., 2 tabs

  7. CVLEACH: Coverage based energy efficient LEACH algorithm

    Directory of Open Access Journals (Sweden)

    Ankit Thakkar

    2012-06-01

    Full Text Available Designing a protocol stack for wireless sensor network (WSNis a challenging task due to energy, computational and storageconstraints. Energy spent for communication between sensornodes dominates the energy spent for the computation [10].Multi-hop short range communication between wireless sensorsnodes is energy efficient compared to single-hop long rangecommunication. Hierarchical clustering is one of the possiblesolutions to save energy of wireless sensor nodes. Low-EnergyAdaptive Clustering Hierarchy (LEACH, Centralized Low-Energy Adaptive Clustering Hierarchy (LEACH-C andAdvanced Low-Energy Adaptive Clustering Hierarchy(ALEACH are energy efficient hierarchical clustering routingprotocol. In this paper we proposed Coverage based Low-EnergyAdaptive Clustering Hierarchy routing protocol – CVLEACH tomake uniform distribution of Cluster Heads (CHs by creatingnon-overlapped cluster regions using overhearing properties ofthe sensor nodes, which makes the routing protocol more energyefficient and prolongs life time of a wireless sensor network.Simulation results show that CVLEACH improves network lifetime compared to LEACH and ALEACH algorithms.

  8. Pesticide leaching through sandy and loamy fields – Long-term lessons learnt from the Danish Pesticide Leaching Assessment Programme

    International Nuclear Information System (INIS)

    The European Union authorization procedure for pesticides includes an assessment of the leaching risk posed by pesticides and their degradation products (DP) with the aim of avoiding any unacceptable influence on groundwater. Twelve-year's results of the Danish Pesticide Leaching Assessment Programme reveal shortcomings to the procedure by having assessed leaching into groundwater of 43 pesticides applied in accordance with current regulations on agricultural fields, and 47 of their DP. Three types of leaching scenario were not fully captured by the procedure: long-term leaching of DP of pesticides applied on potato crops cultivated in sand, leaching of strongly sorbing pesticides after autumn application on loam, and leaching of various pesticides and their DP following early summer application on loam. Rapid preferential transport that bypasses the retardation of the plow layer primarily in autumn, but also during early summer, seems to dominate leaching in a number of those scenarios. - Highlights: • Field-results reveal shortcomings in the EU authorization procedure for pesticides. • The plough layer can be bypassed via preferential transport in e.g. wormholes. • Pesticides properties are decisive for leaching pattern on the sandy fields. • The hydrogeological settings control the leaching patterns on the loamy fields. • Pesticide detection frequency seems to be independent of the month of the year. - Long-term lessons learnt from the Danish Pesticide Leaching Assessment Programme reveals shortcomings in the European Union authorization procedure for pesticides

  9. Mechanical Activation-Assisted Reductive Leaching of Cadmium from Zinc Neutral Leaching Residue Using Sulfur Dioxide

    Science.gov (United States)

    Zhang, Chun; Min, Xiaobo; Chai, Liyuan; Zhang, Jianqiang; Wang, Mi

    2015-12-01

    In this work, zinc neutral leaching residue was mechanically activated by ball-milling. The subsequent leaching behavior and kinetics of cadmium extraction in a mixed SO2-H2SO4 system were studied. Changes in the crystalline phase, lattice distortion, particle size and morphology, which were induced by mechanical activation, were also investigated. The activated samples showed different physicochemical characteristics, and cadmium extraction was found to be easier than for the un-activated samples. Under the same conditions, mechanical activation contributed to higher cadmium leaching. The cadmium extraction kinetics at 75-95°C was found to fit the shrinking core model. The raw neutral leaching residue, and the samples activated for 60 min and 120 min had a calculated activation energy of 65.02 kJ/mol, 59.45 kJ/mol and 53.46 kJ/mol, respectively. The leaching residue was characterized by ICP, XRD and SEM analysis. According to XRD analysis, the main phases in the residue were lead sulfate (PbSO4), zinc sulfide (ZnS) and cadmium sulfide (CdS).

  10. Leaching of heavy metals from steelmaking slags

    Directory of Open Access Journals (Sweden)

    Gomes, J. F. P

    2006-12-01

    Full Text Available Leaching tests with EAF and Ladle slags were performed, using a flow through test and the standard batch test DIN 38414-S4. The previous method was used to simulate the leaching behaviour of steel slags under landfill. The chemical analysis of the leachates during this period shows, in general, for both types of slag, an increase of heavy metal releases with ageing. Standard test method DIN 38414-S4 was used to evaluate leachability of heavy metals by water in unprocessed slags. After more than one year of trials, slag samples submitted to these trials presented very low total leaching levels. The most extracted elements are calcium and magnesium. Nevertheless, in flow-through test, calcium and magnesium leached from solid slags are below 0.5% and all other metals below 0.1%. Leachates obtained with DIN 38414-S4 present, as expected, higher leaching values; however, these are inferior to 5 % (Ca and 1% (other elements.

    Este articulo contiene los resultados obtenidos en ensayos de lixiviación de escorias de acero (horno electrico y cuchara ejecutados siguiendo la metodologia de flujo dinámico así como el ensayo normalizado DIN 38414-S4. El primer ensayo intenta simular el comportamiento de lixiviación de las escorias en vertedero. Para las escorias ensayadas se han complementado los ensayos con el análisis químico de los lixiviados y se ha verificado un aumento de la liberación de metales pesados. El ensayo DIN 38414-S4 se ha utilizado para evaluar la lixiviación por agua de metales pesados, en muestras de escorias originales. Despues de un año de ensayos, se han observado niveles muy bajos de lixiviación. Los elementos mas lixiviados han sido calcio y magnesio. No obstante, en los ensayos de flujo dinámico, el calcio y el magnesio lixiviados de las escorias sólidas era menor de 0,5% y el resto de los otros metales era inferior a 0,1%. Los lixiviados obtenidos con el ensayo DIN 38414-S4 presentan, como era de esperar, valores

  11. Kinetic Investigations on the Leaching of Niobium from a Low-Grade Niobium-Tantalum Ore by Concentrated KOH Solution

    Institute of Scientific and Technical Information of China (English)

    周宏明; 郑诗礼; 张懿

    2004-01-01

    The leaching kinetics of niobium from a low-gr~te niobium-tantalum ore by concentrated KOH solution under atmospheric pressure has been studied. Significant effects of reaction temperature, KOH concentration,stirring speed, particle size and mass ratio of alkali-to-ore on the dissolution rate of niobium were examined. The experimental data of the leaching rates and the observed effects of the relevant operating variables were well interpreted with a shrinking core model under diffusion control. By using the Arrhenius expression, the apparent activation energy for the dissolution of niobium was evaluated. Finally, on the base of the shrinking core model, the rate equation was established.

  12. DYNAMIC RE-CLUSTERING LEACH-BASED (DR-LEACH PROTOCOL FOR WIRELESS SENSOR NETWORKS

    Directory of Open Access Journals (Sweden)

    Abdallah Ijjeh

    2015-11-01

    Full Text Available A Wireless Sensor Network (WSN contains a large number of sensor nodes equipped with limited energy supplies. In most applications, sensor nodes are deployed in a random fashion. Therefore, battery replacement or charging is considered not practical. As a result, routing protocols must be energy-efficient to prolong the network’s lifetime. In this paper, we propose a new Dynamic Re-clustering LEACH-Based protocol (DR-LEACH which aims to reduce the energy consumption and extending the network’s lifetime. The idea is to balance energy consumption of Cluster Heads (CHs by generating clusters with almost equal number of nodes during each round of the network life time. To perform this, we first calculate the optimal number of CHs in each round, and based on that we calculate the optimal size of each cluster. Results show that the proposed protocol improves network lifetime and reduces overall energy consumption compared to LEACH and BCDCP protocols.

  13. Quality Assurance Project Plan for the HWMA/RCRA Closure Certification of the TRA-731 Caustic and Acid Storage Tank System - 1997 Notice of Violation Consent Order

    Energy Technology Data Exchange (ETDEWEB)

    Evans, Susan Kay; Orchard, B. J.

    2002-01-01

    This Quality Assurance Project Plan for the HWMA/RCRA Closure Certification of the TRA-731 Caustic and Acid Storage Tank System is one of two documents that comprise the Sampling and Analysis Plan for the HWMA/RCRA closure certification of the TRA-731 caustic and acid storage tank system at the Idaho National Engineering and Environmental Laboratory. This plan, which provides information about the project description, project organization, and quality assurance and quality control procedures, is to be used in conjunction with the Field Sampling Plan for the HWMA/RCRA Closure Certification of the TRA-731 Caustic and Acid Storage Tank System. This Quality Assurance Project Plan specifies the procedures for obtaining the data of known quality required by the closure activities for the TRA-731 caustic and acid storage tank system.

  14. Quality Assurance Project Plan for the HWMA/RCRA Closure Certification of the TRA-731 Caustic and Acid Storage Tank System - 1997 Notice of Violation Consent Order

    Energy Technology Data Exchange (ETDEWEB)

    Evans, S.K.

    2002-01-31

    This Quality Assurance Project Plan for the HWMA/RCRA Closure Certification of the TRA- 731 Caustic and Acid Storage Tank System is one of two documents that comprise the Sampling and Analysis Plan for the HWMA/RCRA closure certification of the TRA-731 caustic and acid storage tank system at the Idaho National Engineering and Environmental Laboratory. This plan, which provides information about the project description, project organization, and quality assurance and quality control procedures, is to be used in conjunction with the Field Sampling Plan for the HWMA/RCRA Closure Certification of the TRA-731 Caustic and Acid Storage Tank System. This Quality Assurance Project Plan specifies the procedures for obtaining the data of known quality required by the closure activities for the TRA-731 caustic and acid storage tank system.

  15. Best Management Practices for Minimizing Nitrate Leaching from Container-Grown Nurseries

    Directory of Open Access Journals (Sweden)

    Jianjun Chen

    2001-01-01

    Full Text Available Containerized plant production represents an extremely intensive agricultural practice; 40,000 to 300,000 containers may occupy one acre of surface area to which a large amount of chemical fertilizer is applied. Currently, recommended fertilizer application rates for the production of containerized nursery ornamental plants are in excess of plant requirements, and up to 50% of the applied fertilizers may run off or be leached from containers. Among the nutrients leached or allowed to runoff, nitrogen (N is the most abundant and is of major concern as the source of ground and surface water pollution. In this report, current N fertilizer application rates for different container-grown nursery ornamental plants, the amount of nitrate leaching or runoff from containers, and the potential for nitrate contamination of ground and surface water are discussed. In contrast, our best N management practices include: (1 applying fertilizers based on plant species need; (2 improving potting medium�s nutrient holding capacity using obscure mineral additives; (3 using controlled-release fertilizers; and (4 implementing zero runoff irrigation or fertigation delivery systems that significantly reduce nitrate leaching or runoff in containerized plant production and encourage dramatic changes in N management.

  16. Orthophosphate Leaching in St. Augustinegrass and Zoysiagrass Grown in Sandy Soil under Field Conditions.

    Science.gov (United States)

    Gonzalez, Ronald F; Sartain, Jerry B; Kruse, Jason K; Obreza, Thomas A; O'Connor, George A; Harris, Willie G

    2013-01-01

    Phosphorus (P) is required to maintain healthy, high-quality, warm-season turf. However, excessive P applications to soils with poor P retention capabilities may lead to leaching losses to groundwater. This field study was conducted to determine the maximum P fertilizer application rate to (Walt.) [Kuntze] 'Floratam' St. Augustinegrass (St. Augustinegrass) and 'Empire' zoysiagrass (zoysiagrass) below which P leaching is minimized. Five P levels ranging from 0 to 5.0 g P m yr were surface applied as triple superphosphate. Turf was established on an uncoated, low-P sand with negligible P retention capacity. Leaf and root growth, tissue P concentration, soil P concentration, soil P saturation, leachate volume, and orthophosphate (P) concentration in leachates were measured. Mehlich 1-extractable soil P (M1-P) and soil P saturation ratio (PSR) increased with time as the P rate increased. Lower M1-P and PSR values were measured with St. Augustinegrass, which absorbed more P than did zoysiagrass. The root system of St. Augustinegrass was larger and deeper compared with zoysiagrass, promoting greater P uptake and less P leaching. If tissue analysis indicates that P fertilization is required and the soil has the capacity to retain additional P, application of 0.8 g P m yr to zoysiagrass and 1.07 g P m yr to St. Augustinegrass is appropriate and does not result in increased P leaching. PMID:23673941

  17. Leaching Kinetics of Atrazine and Inorganic Chemicals in Tilled and Orchard Soils

    Science.gov (United States)

    Szajdak, Lech W.; Lipiec, Jerzy; Siczek, Anna; Nosalewicz, Artur; Majewska, Urszula

    2014-04-01

    The aim of this study was to verify first-order kinetic reaction rate model performance in predicting of leaching of atrazine and inorganic compounds (K+1, Fe+3, Mg+2, Mn+2, NH4 +, NO3 - and PO4 -3) from tilled and orchard silty loam soils. This model provided an excellent fit to the experimental concentration changes of the compounds vs. time data during leaching. Calculated values of the first-order reaction rate constants for the changes of all chemicals were from 3.8 to 19.0 times higher in orchard than in tilled soil. Higher first-order reaction constants for orchard than tilled soil correspond with both higher total porosity and contribution of biological pores in the former. The first order reaction constants for the leaching of chemical compounds enables prediction of the actual compound concentration and the interactions between compound and soil as affected by management system. The study demonstrates the effectiveness of simultaneous chemical and physical analyses as a tool for the understanding of leaching in variously managed soils.

  18. Nitrogen leaching from short-rotation willow coppice after intensive irrigation with wastewater

    Energy Technology Data Exchange (ETDEWEB)

    Dimitriou, Ioannis; Aronsson, Paer [Swedish Univ. of Agricultural Sciences, Dept. of Short Rotation Forestry, Uppsala (Sweden)

    2004-05-01

    Short-rotation willow coppice is being used in several locations in Sweden as vegetation filters for wastewater treatment. An experiment was conducted in order to quantity the leaching of nitrogen and the toxic effects on the plants after application of wastewater under 'worst case' conditions. Eight 1200-l lysimeters (4 with clay and 4 with sand) were irrigated-fertilised with wastewater from dewatering of sewage sludge or with liquid fertiliser during 8 days, resulting in doses corresponding to 320 kg N ha{sup -1}. Thereafter, plants were daily irrigated with tapwater at a rate of 10 mm d{sup -1} for 123 days. Nitrate-N leaching loads from May until October were approximately 70 kg N ha{sup -1} for clay and 90 kg N ha{sup -1} for sand lysimeters (not significantly different). Leaching loads of ammonium-N and organic N were low (approximately 10 kg N ha{sup -1} for all treatments). The high nitrate-N leaching loads were mainly attributed to the high nitrogen application rate and not to the chemical composition of the fertilisers. No short-term damages to the plants caused by the application of wastewater were observed. (Author)

  19. Leaching performance of imidazolium based ionic liquids in the presence of hydrogen peroxide for recovery of metals from brass waste

    International Nuclear Information System (INIS)

    The application of ionic liquids (ILs), 1-methylimidazolium hydrogen sulfate (HmimHSO4), 1-ethyl-3-methylimidazolium hydrogen sulfate (EmimHSO4) and 1-butyl-3-methylimidazolium chloride (BmimCl) as leaching agents was investigated in the leaching of copper and zinc from brass waste in the presence of an oxidant, hydrogen peroxide (H2O2). Factors that affect copper and zinc dissolution rates such as ionic liquid concentration, time and temperature were investigated. The results indicated that zinc was dissolved in leach solutions with EmimHSO4 and HmimHSO4, completely. Temperature had no considerable influence on copper dissolution rate whilst the rate increased with decreasing IL concentration. In the EmimHSO4 system, higher copper recoveries were achieved with 40% and 60% IL concentrations compared with IL concentrations of 20% and 80% at 40 degree centigrade leaching temperature. Copper dissolution rates decreased with EmimHSO4 concentration at 60 degree centigrade and 80 degree centigrade in the following order; 40%>20%>60%>80%. On the other hand the leaching system with BmimCl generally resulted in poor extractions of copper and zinc. (Author)

  20. Leaching performance of imidazolium based ionic liquids in the presence of hydrogen peroxide for recovery of metals from brass waste

    Energy Technology Data Exchange (ETDEWEB)

    Kelicarslan, A.; Saridede, M. N.

    2016-05-01

    The application of ionic liquids (ILs), 1-methylimidazolium hydrogen sulfate (HmimHSO{sub 4}), 1-ethyl-3-methylimidazolium hydrogen sulfate (EmimHSO{sub 4}) and 1-butyl-3-methylimidazolium chloride (BmimCl) as leaching agents was investigated in the leaching of copper and zinc from brass waste in the presence of an oxidant, hydrogen peroxide (H{sub 2}O{sub 2}). Factors that affect copper and zinc dissolution rates such as ionic liquid concentration, time and temperature were investigated. The results indicated that zinc was dissolved in leach solutions with EmimHSO{sub 4} and HmimHSO{sub 4}, completely. Temperature had no considerable influence on copper dissolution rate whilst the rate increased with decreasing IL concentration. In the EmimHSO{sub 4} system, higher copper recoveries were achieved with 40% and 60% IL concentrations compared with IL concentrations of 20% and 80% at 40 degree centigrade leaching temperature. Copper dissolution rates decreased with EmimHSO{sub 4} concentration at 60 degree centigrade and 80 degree centigrade in the following order; 40%>20%>60%>80%. On the other hand the leaching system with BmimCl generally resulted in poor extractions of copper and zinc. (Author)

  1. Discussion of prolong service life of solid caustic soda pots%延长固碱锅使用寿命的探讨

    Institute of Scientific and Technical Information of China (English)

    李文超

    2012-01-01

    The service condition of the solid caustic soda pots were introduced,and the damage reasons were analyzed.The measures of prolong the service life of solid caustic soda pots were put forward.%介绍了天津渤天化工有限责任公司固碱锅的使用情况,分析了损坏原因,提出了延长固碱锅使用寿命的措施。

  2. Effects of increased deposition of atmospheric nitrogen on an upland moor: leaching of N species and soil solution chemistry.

    Science.gov (United States)

    Pilkington, M G; Caporn, S J M; Carroll, J A; Cresswell, N; Lee, J A; Ashenden, T W; Brittain, S A; Reynolds, B; Emmett, B A

    2005-05-01

    This study was designed to investigate the leaching response of an upland moorland to long-term (10 yr) ammonium nitrate additions of 40, 80 and 120 kg N ha(-1) yr(-1) and to relate this response to other indications of potential system damage, such as acidification and cation displacement. Results showed increases in nitrate leaching only in response to high rates of N input, in excess of 96 and 136 kg total N input ha(-1) yr(-1) for the organic Oh horizon and mineral Eag horizon, respectively. Individual N additions did not alter ammonium leaching from either horizon and ammonium was completely retained by the mineral horizon. Leaching of dissolved organic nitrogen (DON) from the Oh horizon was increased by the addition of 40 kg N ha(-1) yr(-1), but in spite of increases, retention of total dissolved nitrogen reached a maximum of 92% and 95% of 80 kg added N ha(-1) yr(-1) in the Oh and Eag horizons, respectively. Calcium concentrations and calcium/aluminium ratios were decreased in the Eag horizon solution with significant acidification mainly in the Oh horizon leachate. Nitrate leaching is currently regarded as an early indication of N saturation in forest systems. Litter C:N ratios were significantly lowered but values remained above a threshold predicted to increase leaching of N in forests.

  3. A green salt-leaching technique to produce sericin/PVA/glycerin scaffolds with distinguished characteristics for wound-dressing applications.

    Science.gov (United States)

    Aramwit, Pornanong; Ratanavaraporn, Juthamas; Ekgasit, Sanong; Tongsakul, Duangta; Bang, Nipaporn

    2015-05-01

    Sericin/PVA/glycerin scaffolds could be fabricated using the freeze-drying technique; they showed good physical and biological properties and can be applied as wound dressings. However, freeze-drying is an energy- and time-consuming process with a high associated cost. In this study, an alternative, solvent-free, energy- and time-saving, low-cost salt-leaching technique is introduced as a green technology to produce sericin/PVA/glycerin scaffolds. We found that sericin/PVA/glycerin scaffolds were successfully fabricated without any crosslinking using a salt-leaching technique. The salt-leached sericin/PVA/glycerin scaffolds had a porous structure with pore interconnectivity. The sericin in the salt-leached scaffolds had a crystallinity that was as high as that of the freeze-dried scaffolds. Compared to the freeze-dried scaffolds with the same composition, the salt-leached sericin/PVA/glycerin scaffolds has larger pores, a lower Young's modulus, and faster rates of biodegradation and sericin release. When cultured with L929 mouse fibroblast cells, a higher number of cells were found in the salt-leached scaffolds. Furthermore, the salt-leached scaffolds were less adhesive to the wound, which would reduce pain upon removal. Therefore, salt-leached sericin/PVA/glycerin scaffolds with distinguished characteristics were introduced as another choice of wound dressing, and their production process was simpler, more energy efficient, and saved time and money compared to the freeze-dried scaffolds. PMID:25175958

  4. Optimizing conditions for bacterial leaching of copper from discarded mines

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    The effect of process parameters (pH, pulp density, inoculum volume, ferrous content, particle size) on the rate of copper solubilization was analyzed respectively through bioleaching tests with mixed bacteria in shake flasks.These results show that the optimal process parameters are: pH, 1.50-1.80; pulp density, 5wt%; inoculum volume, 10vol%; ferrous content, 2g.L-1; particle size,<0.076 mm.Furthermore, when the pH value is below 1.50 in leaching solution, the iron precipitated can be reduced to a great extent,but it shows low bacterial activity at this pH.Finally, it is emphasized that the optimal parameters are also determined by economical benefit.

  5. Nitrate leaching from intensive organic farms to groundwater

    Directory of Open Access Journals (Sweden)

    O. Dahan

    2013-07-01

    Full Text Available It is commonly presumed that organic agriculture causes only minimal environmental pollution. In this study, we measured the quality of percolating water in the vadose zone, underlying both organic and conventional intensive greenhouses. Our study was conducted in newly established farms where the subsurface underlying the greenhouses has been monitored continuously from their establishment. Surprisingly, intensive organic agriculture relying on solid organic matter, such as composted manure that is implemented in the soil prior to planting as the sole fertilizer, resulted in significant down leaching of nitrate through the vadose zone to the groundwater. On the other hand, similar intensive agriculture that implemented liquid fertilizer through drip irrigation, as commonly practiced in conventional agriculture, resulted in much lower rates of pollution of the vadose zone and groundwater. It has been shown that accurate fertilization methods that distribute the fertilizers through the irrigation system, according to plant demand, during the growing season dramatically reduce the potential for groundwater contamination.

  6. Simfuel dissolution studies in granitic groundwater leaching experiments at VTT

    International Nuclear Information System (INIS)

    The dissolution behaviour of an irradiated analogue of spent nuclear fuel, SIMFUEL, was studied in synthetic granitic groundwater. The release of uranium and the minor components was monitored during static (bach) leaching experiments in oxic and anoxic (N2) atmosphere at 25 deg C. Molybdenum, ruthenium, barium and zirconium showed a trend to congruent dissolution behaviour with UO2 matrix towards the end of the experimental time (540 days) under anoxic conditions. Under oxic conditions, molybdenum and strontium had higher release rates relative to the matrix (the exp. time of 220 days). The presence of particulate material in the leachates in anoxic atmosphere was shown by SEM/EDX and XRD analyses. The material retained on membrane after filtration consisted of Ca-rich and U-rich particles in addition to finely divided material. Calcite (CaCO3) and uranium oxide were identified. (orig.)

  7. Study on Leaching Process of Germanium Fly Ash with Sulfuric Acid%含锗烟尘的硫酸浸出工艺研究

    Institute of Scientific and Technical Information of China (English)

    郑东升; 肖松; 梁杰

    2012-01-01

    为简化含锗烟尘浸出过程,提出一段硫酸浸出工艺。浸出工艺条件为:浸出温度90℃,初始硫酸质量浓度120g/L,液固比8mL/g,浸出时间2.5h,搅拌转速120r/min。在该条件下,锌、锗浸出率分别为99.1%和87.61%左右,最终硫酸质量浓度约34.80g/L。去除不溶性锗后,锗浸出率可达到97.21%。%To simplify the leaching process of germanium fly ash, the one stage sulfuric acid leaching process was studied. The result shows the leaching processing as following: leaching temperature 90℃ initial sulfuric acid concentration 120 g/L, ratio of hquid to solid 5 mL/g, leaching time 2 h, and mixing speed 120 r/min. Under these conditions, the leaching rates of Zn and Ge were about 99.1% and 87.61%, and the concentration of end acid is about 34.80 g/L, and by removal of insoluble germanium, the leaching rate of Germanium could be about 97.21%. Zinc and Germanium can be effectively leached from Germanium fly ash in the leaching process, and the leaching technique is effective and stable.

  8. Long-term leaching mechanisms of ashes and slags; combining laboratory experiments with computer simulations

    International Nuclear Information System (INIS)

    properties similar to those of a medium strength concrete, but had a higher density. The leaching properties of the steel slag concrete and the reference concrete were the same except for chromium, where the leaching from the steel slag concrete was much higher. The release rate was, however, very low, so there should be no environmental problems associated with the use of this concrete. Several computer simulations have been performed using CHEMFRONTS. The input data are based on experimental results. Serial batch experiments have been simulated. The simulation conditions have also been changed to simulate different conditions with the same material 62 refs, 30 figs, 10 tabs

  9. Long-term leaching mechanisms of ashes and slags; Combining laboratory experiments with computer simulations

    Energy Technology Data Exchange (ETDEWEB)

    Baeverman, C.

    1997-12-31

    concrete had physical properties similar to those of a medium strength concrete, but had a higher density. The leaching properties of the steel slag concrete and the reference concrete were the same except for chromium, where the leaching from the steel slag concrete was much higher. The release rate was, however, very low, so there should be no environmental problems associated with the use of this concrete. Several computer simulations have been performed using CHEMFRONTS. The input data are based on experimental results. Serial batch experiments have been simulated. The simulation conditions have also been changed to simulate different conditions with the same material 62 refs, 30 figs, 10 tabs

  10. Evaluation of glass leaching as nutrient source for microalgae growth; Evaluacion del comportamiento de vidrios lixiviados como nutrientes de algas

    Energy Technology Data Exchange (ETDEWEB)

    Grabska, N.; Tamayo, A.; Mazo, M. A.; Pascual, L.; Rubio, J.

    2015-10-01

    Three glasses with an elemental composition similar to the nutrient ratio required for Spirulina platensis growth and with different SiO{sub 2} content have been prepared. The glasses were crushed and sieved into 2 different fractions and the effect of the particle size has been studied in terms of the leaching kinetics of each element. The chemical analysis of the leaching water was used for obtaining the dissolution rate curves for each element taking part of the glass composition. From the calculation of the leaching rate constant and the exponential constant of the lixiviation reaction, it has been evaluated the Spirulina platensis growth in ambient normal conditions of light, temperature and pH of the growing media. It has been concluded that, either from the modification of the chemical composition of the glass or its particle size, it is possible to tune the delivery of the nutrients to match the growth rate of Spirulina platensis. (Author)

  11. Leaching of spent fuel in the presence of environmental material

    International Nuclear Information System (INIS)

    The aim of this work is the study of the alteration kinetics of spent fuels and the making of a status of the radioactivity released by spent fuels in conditions of direct disposal in deep underground. A system has been fitted inside a shielded cell to study the leaching by synthetic groundwater of fuel powder irradiated at 60 GWJ.tU-1 in the presence of environmental material (clay or granite) at 40 bars and 90 deg. C. This system allows to reach and keep reductive conditions characteristic of the redox conditions of a deep geological repository. The preparation of calibrated spent fuel powders and the recovery of the activity fixed by the environmental materials has required the implementation of specific procedures. Similar experiments have been performed in parallel with Simfuel in a controlled area. A first series of experiments has been carried out in 4 environments for each fuel. Important sorption phenomena take place in the environmental materials and the actinide concentrations stabilize rapidly at low values: 10-8 mol/l for U, 10-12 mol/l for Pu and 10-13-10-14 mol/l for Cm. The activity released by 90Sr at the end of each experiment is about two times higher in the presence of clay than in the presence of granite. The average alteration rates are of about 0.2 mg.m-2/day in the presence of granite and 0.4 to 0.6 mg.m-2/day in the presence of clay. They are comparable to those reported in the literature for reducing conditions. Such tests are necessary to determine the leaching rate of spent fuels in reducing conditions and in the absence of environmental materials in order to show the possible effects of these materials. (J.S.)

  12. Comparative evaluation of microbial and chemical leaching processes for heavy metal removal from dewatered metal plating sludge

    Energy Technology Data Exchange (ETDEWEB)

    Bayat, Belgin, E-mail: bbayat@cu.edu.tr [Department of Environmental Engineering, Faculty of Engineering and Architecture, Cukurova University, Balcali, Adana 01330 (Turkey); Sari, Bulent [Department of Environmental Engineering, Faculty of Engineering and Architecture, Cukurova University, Balcali, Adana 01330 (Turkey)

    2010-02-15

    The purpose of the study described in this paper was to evaluate the application of bioleaching technique involving Acidithiobacillus ferrooxidans to recover heavy metals (Zn, Cu, Ni, Pb, Cd and Cr) in dewatered metal plating sludge (with no sulfide or sulfate compounds). The effect of some conditional parameters (i.e. pH, oxidation-reduction potential (ORP), sulfate production) and operational parameters (i.e. pulp density of the sludge and agitation time) were investigated in a 3 l completely mixed batch (CMB) reactor. The metal recovery yields in bioleaching were also compared with chemical leaching of the sludge waste using commercial inorganic acids (sulfuric acids and ferric chloride). The leaching of heavy metals increased with decreasing of pH and increasing of ORP and sulfate production during the bioleaching experiment. Optimum pulp density for bioleaching was observed at 2% (w/v), and leaching efficiency decreased with increasing pulp density in bioleaching experiments. Maximum metal solubilization (97% of Zn, 96% of Cu, 93% of Ni, 84% of Pb, 67% of Cd and 34% of Cr) was achieved at pH 2, solids contents of 2% (w/v), and a reaction temperature of 25 {+-} 2 deg. C during the bioleaching process. The maximum removal efficiencies of 72% and 79% Zn, 70% and 75% Cu, 69% and 73% Ni, 57% and 70% Pb, 55% and 65% Cd, and 11% and 22% Cr were also attained with the chemical leaching using sulfuric acids and ferric chloride, respectively, at pH 2, solids contents of 2% (w/v), and a reaction temperature of 25 {+-} 2 deg. C during the acid leaching processes. The rates of metal leaching for bioleaching and chemical leaching are well described by a kinetic equation related to time. Although bioleaching generally requires a longer period of operation compared to chemical leaching, it achieves higher removal efficiency for heavy metals. The efficiency of leaching processes can be arranged in descending order as follows: bioleaching > ferric chloride leaching > sulfuric

  13. Comparative evaluation of microbial and chemical leaching processes for heavy metal removal from dewatered metal plating sludge

    International Nuclear Information System (INIS)

    The purpose of the study described in this paper was to evaluate the application of bioleaching technique involving Acidithiobacillus ferrooxidans to recover heavy metals (Zn, Cu, Ni, Pb, Cd and Cr) in dewatered metal plating sludge (with no sulfide or sulfate compounds). The effect of some conditional parameters (i.e. pH, oxidation-reduction potential (ORP), sulfate production) and operational parameters (i.e. pulp density of the sludge and agitation time) were investigated in a 3 l completely mixed batch (CMB) reactor. The metal recovery yields in bioleaching were also compared with chemical leaching of the sludge waste using commercial inorganic acids (sulfuric acids and ferric chloride). The leaching of heavy metals increased with decreasing of pH and increasing of ORP and sulfate production during the bioleaching experiment. Optimum pulp density for bioleaching was observed at 2% (w/v), and leaching efficiency decreased with increasing pulp density in bioleaching experiments. Maximum metal solubilization (97% of Zn, 96% of Cu, 93% of Ni, 84% of Pb, 67% of Cd and 34% of Cr) was achieved at pH 2, solids contents of 2% (w/v), and a reaction temperature of 25 ± 2 deg. C during the bioleaching process. The maximum removal efficiencies of 72% and 79% Zn, 70% and 75% Cu, 69% and 73% Ni, 57% and 70% Pb, 55% and 65% Cd, and 11% and 22% Cr were also attained with the chemical leaching using sulfuric acids and ferric chloride, respectively, at pH 2, solids contents of 2% (w/v), and a reaction temperature of 25 ± 2 deg. C during the acid leaching processes. The rates of metal leaching for bioleaching and chemical leaching are well described by a kinetic equation related to time. Although bioleaching generally requires a longer period of operation compared to chemical leaching, it achieves higher removal efficiency for heavy metals. The efficiency of leaching processes can be arranged in descending order as follows: bioleaching > ferric chloride leaching > sulfuric acid

  14. Impact of weather variability on nitrate leaching

    Science.gov (United States)

    Richards, Karl; Premrov, Alina; Hackett, Richard; Coxon, Catherine

    2016-04-01

    The loss of nitrate (NO3 - N) to water via leaching and overland flow contributes to eutrophication of freshwaters, transitional and near coastal waters with agriculture contributing significantly to nitrogen (N) loading to these water. Environmental regulations, such as the Nitrates and Water Framework Directives, have increased constraints on farmers to improve N management in regions at risk of NO3--N loss to water. In addition, farmers also have to manage their systems within a changing climate as the imapcts of climate change begin to impact resulting in more frequent extreme events such as floods and droughts. The objective of this study was to investigate the link between weather volatility and the concentration of leached NO3--N spring barley. Leaching was quantified under spring barley grown on a well-drained, gravelly sandy soil using ceramic cup samplers over 6 drainage years under the same farming practices and treatments. Soil solution NO3--N concentrations under spring barley grown by conventional inversion ploughing and reduced tillage were compared to weather parameters over the period. Weather was recorded at a national Met Eireann weather station on site. Soil solution NO3--N varied significantly between years. Within individual years NO3--N concentrations varied over the drainage season, with peak concentrations generally observed in the autumn time, decreasing thereafter. Under both treatments there was a three-fold difference in mean annual soil solution NO3--N concentration over the 6 years with no change in the agronomic practices (crop type, tillage type and fertiliser input). Soil solution nitrate concentrations were significantly influenced by weather parameters such as rainfall, effective drainage and soil moisture deficit. The impact of climate change in Ireland could lead to increased NO3--N loss to water further exacerbating eutrophication of sensitive estuaries. The increased impact on eutrophication of waters, related to climatic

  15. Leaching refuse after sphalerite mineral for extraction zinc and cobalt

    Directory of Open Access Journals (Sweden)

    S. Brožová

    2016-07-01

    Full Text Available The paper deals with a possibility of zinc and cobalt extraction from refuse after sphalerite mineral leaching. It contains theoretic analysis of hydrometallurgical processes. Practical part describes samples and their leaching in 10 % and 20 % sulphuric acid. In the end of the paper it is evaluated under which conditions the highest yield of zinc and cobalt from refuse after sulphide ore leaching is reached.

  16. Leaching of vanadium from sulphuric acid manufacture spent catalysts

    OpenAIRE

    García, Diego Juan; Lozano Blanco, Luis Javier; Mulero Vivancos, María Dolores

    2001-01-01

    Recovery of vanadium contained in spent catalysts from the manufacture of sulphuric acid has been studied in this work, resulting in an industrial multistage process for the treatment of them avoiding direct deposition or dumping. Characterization of supplied spent catalysts samples, confirmed vanadium levels showed in the literature. The study of variables influencing leaching process: type of leaching agent, leaching agent concentration, S/L ratio, stirring speed and temperature, allows to ...

  17. Leaching refuse after sphalerite mineral for extraction zinc and cobalt

    OpenAIRE

    S. Brožová; J. Drápala; Kursa, M.; Pustějovská, P.; S. Jursová

    2016-01-01

    The paper deals with a possibility of zinc and cobalt extraction from refuse after sphalerite mineral leaching. It contains theoretic analysis of hydrometallurgical processes. Practical part describes samples and their leaching in 10 % and 20 % sulphuric acid. In the end of the paper it is evaluated under which conditions the highest yield of zinc and cobalt from refuse after sulphide ore leaching is reached. Web of Science 55 3 499 497

  18. Research on the Process for Conventional Leaching and Oxidation Leaching of Indium Sulfide%硫化铟常规酸浸和氧化酸浸试验研究

    Institute of Scientific and Technical Information of China (English)

    韦岩松; 马宸; 黎铉海

    2011-01-01

    用人工合成的硫化铟模拟实际硫化铟,研究了硫化铟在硫酸体系中常规浸出和以高锰酸钾、双氧水为氧化剂的氧化浸出的浸出效果和工艺条件.结果表明:在搅拌速度为800 r/min、物料粒度为75~96μm、液固比为300:1、温度为80℃、硫酸初始浓度为2.0 mol/L的条件下,常规浸出60min,铟的浸出率为84.9%;而在相同条件下加入氧化剂KMnO4或H2O2进行氧化浸出,只需20min就可使铟的浸出率达到94.9%或92.8%.在温度<70℃时,氧化剂的效应起主要作用,高锰酸钾的氧化效果比双氧水更明显;在温度>70℃时,温度效应占主导地位,两种氧化剂的影响差别不大..%By using the synthetic Indium sulfide to simulate the actual indium sulfide, the leaching effect and leaching process conditions of indium sulfide With the conventional leaching method and the oxidation leaching of potassium permanganate and hydrogen peroxide as the oxidant in sulfuric acid leaching system were studied. The results showed that under conditions of the stirring speed at 800 r/min, particle size of 75 ~ 96 μn, the liquid-solid ratio of 300: 1, the temperature at 80 ℃, and initial concentration of sulfuric acid of 2.0 mol/L for leaching 60 min, the leaching rate of indium arrived at 84. 9% by the conventional leaching method. Under the same conditions, the leaching rate reached 94. 9% or 92. 8% by adding oxidant KMnO4 or H202 to realize oxidation leaching only for 20 min. At temperature <70 ℃, the oxidant plays a major role, where the effect of potassium permanganate is more obvious than the that of hydrogen peroxide; At temperature > 70 ℃, the temperature effect plays a leading rule, and the impact of the two oxidants are less different.

  19. Coupling GIS with Nitrogen Leaching Models

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Geographical information systems (GIS) are increasingly being applied to surface and subsurface flow and transport modeling issues. In this paper, more attentions are focused on the methodology and strategies of coupling GIS with non-point pollution models. Suggestions are made on how to best integrate current available or selected nitrogen leaching models, especially in the aspect of programming development so as to effectively and flexibly address the specific tasks. The new possibilities for dealing with non-point pollution problems at a regional scale are provided in the resulting integrated approach, including embedding grid-based GIS components in models.

  20. Lead sulphate leaching by sodium chloride solution

    OpenAIRE

    Conić Vesna T.; Pešovski Branka D.; Cvetkovski Vladimir B.; Stanojević-Šimšić Zdenka S.; Dragulović Suzana S.; Simonović Danijela B.; Dimitrijević Silvana B.

    2013-01-01

    Bioleaching treatment of complex multi-metallic Cu-Zn-Pb-Ag-Au mineral concentrates leds to the formation, besides easily soluble zinc and cooper sulphates, of hardly soluble lead (II) sulfate (PbSO4) sludge. To determine the leaching parameters of PbSO4 with NaCl in the bioleaching residue, lead sulphate solution was synthetically prepared. The effect of process parameters, namely NaCl concentration, solid:liquid phase ratio, processing time, temperature and Cl ions was examined. It wa...

  1. Effects of Sodium Citrate on the Ammonium Sulfate Recycled Leaching of Low-Grade Zinc Oxide Ores

    Science.gov (United States)

    Yang, Kun; Li, Shi-wei; Zhang, Li-bo; Peng, Jin-hui; Ma, Ai-yuan; Wang, Bao-bao

    2016-03-01

    The effects of sodium citrate on ammonium sulfate recycled leaching of low-grade zinc oxide ores were studied. By applying various kinds of detection and analysis techniques such as chemical composition analysis, chemical phase method, scanning electron microscopy and energy dispersive spectrum (SEM/EDS), X-ray diffraction (XRD) and Fourier-transforming infrared spectrum (FT-IR), zinc raw ore, its leaching slag and the functional mechanism of sodium citrate were investigated. Based on a comprehensive analysis, it can be concluded that in contrast to hemimorphite (Zn4Si2O7(OH)2 · H2O), amorphous smithsonite (ZnCO3) and zinc silicate (Zn2SiO4) prove to be refractory phases under ammonium sulfate leaching, while sodium citrate has a better chelating action with the refractory phases, resulting in a higher zinc leaching rate. Under conditions of [NH3]/[NH3]T molar ratio being 0.5, [NH3]T being 7.5 mol/L, [Na3C6H5O7] being 0.2 mol/L, S/L ratio being 1:5, temperature being 303 K, holding time being 1 h in each of the two stages, and stirring rate being 300 rpm, the leaching rate of zinc reached 93.4%. In this article, sulfate ammonium recycled technology also reveals its unique advantage in processing low-grade zinc oxide ores accompanied by high silicon and high alkaline gangue.

  2. Influence of microstructure on stress corrosion cracking of mild steel in synthetic caustic-nitrate nuclear waste solution

    International Nuclear Information System (INIS)

    The influence of alloy microstructure on stress corrosion cracking of mild steel in caustic-nitrate synthetic nuclear waste solutions was studied. An evaluation was made of the effect of heat treatment on a representative material (ASTM A 516 Grade 70) used in the construction of high activity radioactive waste storage tanks at Savannah River Plant. Several different microstructures were tested for susceptibility to stress corrosion cracking. Precracked fracture specimens loaded in either constant load or constant crack opening displacement were exposed to a variety of caustic-nitrate and nitrate solutions. Results were correlated with the mechanical and corrosion properties of the microstructures. Crack velocity and crack arrest stress intensity were found to be related to the yield strength of the steel microstructures. Fractographic evidence indicated pH depletion and corrosive crack tip chemistry conditions even in highly caustic solutions. Experimental results were compatible with crack growth by a strain-assisted anodic dissolution mechanism; however, hydrogen embrittlement also was considered possible

  3. Cadmium leaching from thermal treated and gamma irradiated Mexican aluminosilicates

    Energy Technology Data Exchange (ETDEWEB)

    Davila-Rangel, J.I. [Departamento de Quimica, Instituto Nacional de Investigaciones Nucleares, Apdo. Postal 18-1027, Mexico 11801, D.F. (Mexico); Unidad Academica Centro Regional de Estudios Nucleares, Universidad Autonoma de Zacatecas Cipres 10, Frac. La Penuela, Zacatecas, Zacatecas 98068 (Mexico); Facultad de Ciencias, Universidad Autonoma del Estado de Mexico, Instituto Literario No. 100 Col. Centro C.P. 50000, Toluca, Edo. de Mexico (Mexico); Solache-Rios, M. [Departamento de Quimica, Instituto Nacional de Investigaciones Nucleares, Apdo. Postal 18-1027, Mexico 11801, D.F. (Mexico)], E-mail: msr@nuclear.inin.mx

    2008-10-15

    Thermal and radiation effects on the leaching of cadmium from two cadmium exchanged zeolitic tuffs and one clay were determined. The cadmium exchanged aluminosilicates were heated at different temperatures (500, 700, 900 and 1100 {sup o}C), and the materials were then treated with NaCl (1 M and 5 M) and HNO{sub 3} (0.001 M and 1 M) solutions to determine the leaching behaviour of cadmium from the materials. The stability of cadmium in the materials increased as the heating temperature was increased. Cadmium leaching from gamma irradiated and heated materials at 1100 {sup o}C was higher than leaching from non-irradiated samples.

  4. Leaching of polyphase nuclear waste ceramics: microstructural and phase characterization

    International Nuclear Information System (INIS)

    The leaching of complex polyphase nuclear waste ceramics is described in the context of the geochemically established dissolution behavior of the constituent phases. Static leach tests conducted on ceramic monoliths in deionized water, in simulated silicate, and in brine groundwaters, conforming to Materials Characterization Center standards and an accelerated, microscopic leach test, were used to identify the processes. Dissolution and formation of surface passivation layers are discussed in terms of hydrolysis and the adsorption of the metal hydroxocomplexes onto the monolith surface. The factors observed to affect dissolution are pertinent to the leaching of other polyphase nuclear waste ceramics. 11 figures, 1 table

  5. Effect of peroxodisulfate on uranium leaching with ammonium bicarbonate

    Directory of Open Access Journals (Sweden)

    Nurbek Nurpeisov

    2013-05-01

    Full Text Available In this study, uranium leaching from ore material using acid solution and bicarbonate in a presence peroxodisulfate ion was examined. For experiments two different tips of leaching methods were used: leaching in static and dynamic conditions. The determination of uranium concentrations in product solutions were analyzed by titrimetric (by ammonia vanadate solution method. The maximum yield of uranium leached with ammonium bicarbonate in a presence of ammonium peroxodisulfate (5 g/L was only 33%, which is half the corresponding value obtained by sulfuric acid (65%.

  6. Carbonate leaching of uranium and hydrogen peroxide stabilizer therefor

    International Nuclear Information System (INIS)

    In the carbonate leaching process for the solution mining of subterranean uranium containing formations in which an injection well is drilled and completed within the uranium formation; alkaline carbonate uranium leaching solution and sufficient hydrogen peroxide are injected through the injection wells into the formation whereby uranium values are produced from production wells, characterized by providing in the leaching solution a mixture of 1-hydroxyethylidene-1,1-diphosphonic acid and an alkali metal pyrophosphate in a weight ratio of from 1 to 10 to 10 to 1, the amount of said mixture being sufficient to inhibit decomposition of the hydrogen peroxide in said leaching solution

  7. Cadmium leaching from thermal treated and gamma irradiated Mexican aluminosilicates

    International Nuclear Information System (INIS)

    Thermal and radiation effects on the leaching of cadmium from two cadmium exchanged zeolitic tuffs and one clay were determined. The cadmium exchanged aluminosilicates were heated at different temperatures (500, 700, 900 and 1100 oC), and the materials were then treated with NaCl (1 M and 5 M) and HNO3 (0.001 M and 1 M) solutions to determine the leaching behaviour of cadmium from the materials. The stability of cadmium in the materials increased as the heating temperature was increased. Cadmium leaching from gamma irradiated and heated materials at 1100 oC was higher than leaching from non-irradiated samples

  8. Actinide speciation in glass leach-layers: An EXAFS study

    Energy Technology Data Exchange (ETDEWEB)

    Biwer, B.M.; Soderholm, L. [Argonne National Lab., IL (United States); Greegor, R.B. [Boeing Co., Seattle, WA (United States); Lytle, F.W. [EXAFS Co., Pioche, NV (United States)

    1996-12-31

    Uranium L{sub 3} X-ray absorption data were obtained from two borosilicate glasses, which are considered as models for radioactive wasteforms, both before and after leaching. Surface sensitivity to uranium speciation was attained by a novel application of simultaneous fluorescence and electron-yield detection. Changes in speciation are clearly discernible, from U(VI) in the bulk to (UO{sub 2}){sup 2+}-uranyl in the leach layer. The leach-layer uranium concentration variations with leaching times are also determined from the data.

  9. Fertilizer management effects on nitrate leaching and indirect nitrous oxide emissions in irrigated potato production.

    Science.gov (United States)

    Venterea, Rodney T; Hyatt, Charles R; Rosen, Carl J

    2011-01-01

    Potato ( L.) is a N-intensive crop, with high potential for nitrate (NO) leaching, which can contribute to both water contamination and indirect nitrous oxide (NO) emissions. Two approaches that have been considered for reducing N losses include conventional split application (CSA) of soluble fertilizers and single application of polymer-coated urea (PCU). The objectives of this study were to: (i) compare NO leaching using CSA and two PCUs (PCU-1 and PCU-2), which differed in their polymer formulations, and (ii) use measured NO leaching rates and published emissions factors to estimate indirect NO emissions. Averaged over three growing seasons (2007-2009), NO leaching rates were not significantly different among the three fertilizer treatments. Using previously reported direct NO emissions data from the same experiment, total direct plus indirect growing season NO emissions with PCU-1 were estimated to be 30 to 40% less than with CSA. However, PCU-1 also resulted in greater residual soil N after harvest in 2007 and greater soil-water NO in the spring following the 2008 growing season. These results provide evidence that single PCU applications for irrigated potato production do not increase growing season NO leaching compared with multiple split applications of soluble fertilizers, but have the potential to increase N losses after the growing season and into the following year. Estimates of indirect NO emissions ranged from 0.8 to 64% of direct emissions, depending on what value was assumed for the emission factor describing off-site conversion of NO to NO. Thus, our results also demonstrate how more robust models are needed to account for off-site conversion of NO to NO, since current emission factor models have an enormous degree of uncertainty.

  10. Fertilizer management effects on nitrate leaching and indirect nitrous oxide emissions in irrigated potato production.

    Science.gov (United States)

    Venterea, Rodney T; Hyatt, Charles R; Rosen, Carl J

    2011-01-01

    Potato ( L.) is a N-intensive crop, with high potential for nitrate (NO) leaching, which can contribute to both water contamination and indirect nitrous oxide (NO) emissions. Two approaches that have been considered for reducing N losses include conventional split application (CSA) of soluble fertilizers and single application of polymer-coated urea (PCU). The objectives of this study were to: (i) compare NO leaching using CSA and two PCUs (PCU-1 and PCU-2), which differed in their polymer formulations, and (ii) use measured NO leaching rates and published emissions factors to estimate indirect NO emissions. Averaged over three growing seasons (2007-2009), NO leaching rates were not significantly different among the three fertilizer treatments. Using previously reported direct NO emissions data from the same experiment, total direct plus indirect growing season NO emissions with PCU-1 were estimated to be 30 to 40% less than with CSA. However, PCU-1 also resulted in greater residual soil N after harvest in 2007 and greater soil-water NO in the spring following the 2008 growing season. These results provide evidence that single PCU applications for irrigated potato production do not increase growing season NO leaching compared with multiple split applications of soluble fertilizers, but have the potential to increase N losses after the growing season and into the following year. Estimates of indirect NO emissions ranged from 0.8 to 64% of direct emissions, depending on what value was assumed for the emission factor describing off-site conversion of NO to NO. Thus, our results also demonstrate how more robust models are needed to account for off-site conversion of NO to NO, since current emission factor models have an enormous degree of uncertainty. PMID:21712579

  11. Mathematical modeling of an exothermic leaching reaction system: pressure oxidation of wide size arsenopyrite participates

    Science.gov (United States)

    Papangelakis, V. G.; Berk, D.; Demopoulos, G. P.

    1990-10-01

    In the design of processes involving exothermic reactions, as is the case of several sulfide leaching systems, it is desirable to utilize the energy liberated by the reaction to drive the reactor toward autogenous operation. For optimal reactor design, models which couple leaching kinetics and heat effects are needed. In this paper, the principles of modeling exothermic leaching reactions are outlined. The system investigated is the high-temperature (160 °C to 200 °C) pressure (O2) oxidation of arsenopyrite (FeAsS). The reaction system is characterized by three consecutive reactions: (1) heterogeneous dissolution of arsenopyrite particles, (2) homogeneous oxidation of iron(II) to iron(III), and (3) precipitation of scorodite (FeAsO4-2H2O). The overall kinetics is controlled by the arsenopyrite surface reaction. There was good agreement between laboratory-scale batch tests and model predictions. The model was expanded to simulate the performance of large-scale batch and single-stage continuous stirred tank reactor (CSTR) for the same rate-limiting regime. Emphasis is given to the identification of steady-state temperatures for autogenous processing. The effects of operating variables, such as feed temperature, slurry density, and retention time, on reactor operation and yield of leaching products are discussed.

  12. 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

  13. Risk of Leaching in Soils Amended by Compost and Digestate from Municipal Solid Waste

    Directory of Open Access Journals (Sweden)

    Marta García-Albacete

    2014-01-01

    Full Text Available New European directives have proposed the direct application of compost and digestate produced from municipal solid wastes as organic matter sources in agricultural soils. Therefore information about phosphorus leaching from these residues when they are applied to the soil is increasingly important. Leaching experiments were conducted to determine the P mobility in compost and digestate mixtures, supplying equivalent amounts to 100 kg P ha−1 to three different types of soils. The tests were performed in accordance with CEN/TS 14405:2004 analyzing the maximum dissolved reactive P and the kinetic rate in the leachate. P biowaste fractionation indicated that digestate has a higher level of available P than compost has. In contrast, P losses in leaching experiments with soil-compost mixtures were higher than in soil-digestate mixtures. For both wastes, there was no correlation between dissolved reactive P lost and the water soluble P. The interaction between soil and biowaste, the long experimentation time, and the volume of leachate obtained caused the waste’s wettability to become an influential parameter in P leaching behavior. The overall conclusion is that kinetic data analysis provides valuable information concerning the sorption mechanism that can be used for predicting the large-scale behavior of soil systems.

  14. Kinetics of the leaching of TiO2 from Ti-bearing blast furnace slag

    Institute of Scientific and Technical Information of China (English)

    LIU Xiao-hua; GAI Guo-sheng; YANG Yu-fen; SUI Zhi-tong; LI Li; FU Jian-xia

    2008-01-01

    Ti-bearing blast furnace slag is a valuable secondary resource containing about 24 percent of TiO2. In this paper a process of leaching Ti-bearing blast furnace slag with sulfuric acid to recover TiO2, and the kinetics of that reaction, are described. Under laboratory conditions the rate is controlled by a chemical reaction. The leaching reaction is in accord with a shrinking un-reacted-core model. The apparent reaction order of the leaching reaction was 1.222 and the apparent activation energy was 87.01 kJ/mol. The model fits the observed data well until 90% of the TiO2 has be leached from the particles. The model disagrees with observations during later periods of the reaction because the solution becomes supersaturated with Ti ions, which precipitate as H2TiO4. The assumptions of constant reactant concentration and that there is no effect from the product layer on diffusion, also cause the model to deviate from the actual values.

  15. Characterization of solute transport parameters in leach ore:inverse modeling based on column experiments

    Institute of Scientific and Technical Information of China (English)

    Sheng PENG

    2009-01-01

    Heap leaching is essentially a process in which metals are extracted from mine ores with lixiant. For a better understanding and modeling of this process, solute transport parameters are required to characterize the solute transport system of the leach heap. For porous media like leach ores, which contain substantial gravelly particles and have a broad range of particle size distributions, traditional small-scale laboratory experimental apparatus is not appropriate. In this paper, a 2.44m long, 0.3 m inner diameter column was used for tracer test with boron as the tracer. Tracer tests were conducted for 2 bulk densities (1.92 and 1.62g/cm3) and 2 irrigation rates (2 and 5 L/(mE. h-i)). Inverse modeling with two-region transport model using computer code CXTFIT was conducted based on the measured breakthrough curves to estimate the transport parameters. Fitting was focused on three parameters: dispersion coefficient D, partition coefficient r, and mass transfer coefficient ω. The results turned out to fall within reasonable ranges. Sensitivity analysis was conducted for the three parameters and showed that the order of sensitivity is β > ω > D. In addition, scaling of these parameters was discussed and applied to a real scale heap leach to predict the tracer breakthrough.

  16. YACON INULIN LEACHING DURING HOT WATER BLANCHING

    Directory of Open Access Journals (Sweden)

    Caroline Fenner Scher

    2015-10-01

    Full Text Available ABSTRACTYacon roots contain inulin, which has prebiotic properties and it may be used as sucrose or fat substitutes. However, inulin is very soluble in water. The loss of this important nutrient during blanching is caused mainly by diffusion or leaching, which might be diminished if blanching temperature - time conditions are correctly employed. The aim of this study was to determine the leaching of the sugars inulin, glucose and fructose, present in yacon roots, during hot water blanching under different time/temperature conditions. The samples were cleaned and peeled and cut into geometric forms of 1.75 ± 0.35 mm thick disks. A complete factorial experimental design was used, and the treatments of the samples were compared using the Tukey test. The results indicated that the time and temperature were significant in the dissolution of the sugars. The lowest inulin losses occurred at temperatures and times lower than 60 ºC and 3 minutes. For all temperatures, the lowest glucose and fructose losses were obtained at time lower than 3 and 5 minutes, respectively.

  17. Heterogeneous LEACH Protocol for Wireless Sensor Networks

    Directory of Open Access Journals (Sweden)

    Nishi Sharma

    2013-07-01

    Full Text Available Wireless Sensor Networks are networks of large number of tiny, battery powered sensor nodes having limited on-board storage, processing, and radio capabilities. Nodes sense and send their reports toward a processing center which is called base station. Since this transmission and reception process consumes lots of energy as compare to data processing, Designing protocols and applications for such networks has to be energy aware in order to prolong the lifetime of the network. Generally, real life applications deal with such Heterogeneity rather than Homogeneity. In this paper, a protocol is proposed, which is heterogeneous in energy. We analyze the basic distributed clustering routing protocol LEACH (Low Energy Adaptive Clustering Hierarchy, which is a homogeneous system, and then we study the impact of heterogeneity in energy of nodes to prolong the life time of WSN. Simulation results using MATLAB shows that the proposed Leach-heterogeneous system significantly reduces energy consumption and increase the total lifetime of the wireless sensor network.

  18. A Simulator for Copper Ore Leaching

    Energy Technology Data Exchange (ETDEWEB)

    Travis, B.

    1999-05-14

    This is the final report of a one-year, Laboratory Directed Research and Development (LDRD) project at Los Alamos National Laboratory (LANL). Copper is a strategic metal and the nation needs a secure supply both for industrial use and military needs. However, demand is growing worldwide and is outstripping the ability of the mining industry to keep up. Improved recovery methods are critically needed to maintain the balance of supply and demand. The goal of any process design should be to increase the amount of copper recovered, control movement of acid and other environmentally harmful chemicals, and reduce energy requirements. To achieve these ends, several improvements in current technology are required, the most important of which is a better understanding of, and the ability to quantify, how fluids move through heterogeneous materials in a complex chemical environment. The goal of this project is create a new modeling capability that couples hydrology with copper leaching chemistry . once the model has been verified and validated, we can apply the model to specific problems associated with heap leaching (flow channeling due to non-uniformities in heap structure, precipitation/dissolution reactions, and bacterial action), to understand the causes of inefficiencies, and to design better recovery systems. We also intend to work with representatives of the copper mining industry to write a coordinated plan for further model development and application that will provide economic benefits to the industry and the nation.

  19. Transmission Time and Throughput analysis of EEE LEACH, LEACH and Direct Transmission Protocol: A Simulation Based Approach

    Directory of Open Access Journals (Sweden)

    Meenakshi Sharma

    2012-10-01

    Full Text Available This paper gives a brief description about some routing protocols like EEE LEACH, LEACH and DirectTransmission protocol (DTx in Wireless Sensor Network (WSN and a comparison study of theseprotocols based on some performance matrices. Addition to this an attempt is done to calculate theirtransmission time and throughput. To calculate these, MATLAB environment is used. Finally, on the basisof the obtained results from the simulation, the above mentioned three protocols are compared. Thecomparison results show that, the EEE LEACH routing protocol has a greater transmission time thanLEACH and DTx protocol and with smaller throughput

  20. Transmission Time and Throughput analysis of EEE LEACH, LEACH and Direct Transmission Protocol: A Simulation Based Approach

    Directory of Open Access Journals (Sweden)

    Meenakshi Sharma

    2012-12-01

    Full Text Available This paper gives a brief description about some routing protocols like EEE LEACH, LEACH and DirectTransmission protocol (DTx in Wireless Sensor Network (WSN and a comparison study of theseprotocols based on some performance matrices. Addition to this an attempt is done to calculate theirtransmission time and throughput. To calculate these, MATLAB environment is used. Finally, on the basisof the obtained results from the simulation, the above mentioned three protocols are compared. Thecomparison results show that, the EEE LEACH routing protocol has a greater transmission time thanLEACH and DTx protocol and with smaller throughput.

  1. Recommended Guanidine Suppressor for the Next-Generation Caustic-Side Solvent Extraction Process

    Energy Technology Data Exchange (ETDEWEB)

    Moyer, Bruce A [ORNL; Delmau, Laetitia Helene [ORNL; Duncan, Nathan C [ORNL; Ensor, Dale [Tennessee Technological University; Hill, Talon G [ORNL; Lee, Denise L [ORNL; Roach, Benjamin D [ORNL; Sloop Jr, Frederick {Fred} V [ORNL; Williams, Neil J [ORNL

    2013-01-01

    The guanidine recommended for the Next-Generation Caustic-Side is N,N ,N -tris(3,7-dimethyloctyl)guanidine (TiDG). Systematic testing has shown that it is significantly more lipophilic than the previously recommended guanidine DCiTG, the active extractant in the commercial guanidine product LIX -79, while not otherwise changing the solvent performance. Previous testing indicated that the extent of partitioning of the DCiTG suppressor to the aqueous strip solution is significantly greater than expected, potentially leading to rapid depletion of the suppressor from the solvent and unwanted organic concentrations in process effluents. Five candidate guanidines were tested as potential replacements for DCiTG. The tests included batch extraction with simulated waste and flowsheet solutions, third-phase formation, emulsion formation, and partition ratios of the guanidine between the solvent and aqueous strip solution. Preliminary results of a thermal stability test of the TiDG solvent at one month duration indicated performance approximately equivalent to DCiTG. Two of the guanidines proved adequate in all respects, and the choice of TiDG was deemed slightly preferable vs the next best guanidine BiTABG.

  2. Dynamic caustics test of blast load impact on neighboring different cross-section roadways

    Institute of Scientific and Technical Information of China (English)

    Guo Dongming; Zhou Baowei; Liu Kang; Yang Renshu; Yan Pengyang

    2016-01-01

    Using digital laser dynamic caustics experimental system and conducting simulation experiment researched the influence rule of blasting excavation of a new roadway on neighboring existed different cross-section roadways. The experimental results show that the influence of blast load on adjacent road-way has a good relationship with the cross-section of roadway. The expansion distance of precrack existed in circular, arch-wall, rectangular roadway is respectively 1.76, 1.61 and 0 cm under blast load. At the same time, the direct-blast side of rectangular roadway has more obvious damage compared with circular and arch-wall roadway. It explains that plane reflects more stress wave than arc, so that it exerts more tensile failure in the direct-blast side, which leads to less stress wave diffracting to the precrack in the back-blast side. When the precrack extends, higher value dynamic stress intensity factor in circular roadway works longer than that of arch-wall roadway. Indirectly, it explains that plane’s weakening func-tion on stress wave is significantly stronger than arc. Stress wave brings about self-evident influence on the upper and bottom endpoints of the rectangular roadway, and it respectively extends 1.03, 2.06 cm along the line link direction of the center of the blasthole and the upper and bottom endpoints on the right wall.

  3. Elimination of the calcium cycle: direct electrolytic causticizing of Kraft smelt. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Pfromm, P.; Winnick, J.

    1999-01-19

    An electrochemical molten salt alternative to the classic Kraft causticizing process has been investigated and the feasibility of the process was successfully shown. The experiments include (A) the determination of background thermal decomposition gases, (B) the electrolysis of a sodium carbonate only smelt to show that sodium oxide can be electrochemically produced, and (C) electrolysis of a synthetic smelt containing 80 mole % Na{sub 2}CO{sub 3} and 20 mole % Na{sub 2}S. The experiments show, that sodium hydroxide (NaOH) was produced by the electrochemical reduction of sodium carbonate to sodium oxide in the molten state. In the experiment containing sodium sulfide, there was formation of less than 5 mole % of polysulfide. Energy savings on the order of 500,000 BTU per ton of kraft pulp produced are estimated, based on the energy used by the mill. Operating costs are estimated to be currently similar to conventional processing. However, price increases of fossil fuels and increased co-generation of electricity in the mill will give the electrolytical process significant cost advantages.

  4. Elimination of the Calcium Cycle: Direct Electrolytic Causticizing of Kraft Smelt, Final report

    Energy Technology Data Exchange (ETDEWEB)

    P. Pfromm, J. Winnick

    1999-01-31

    An electrochemical molten salt alternative to the classic kraft causticizing process has been investigated and the feasibility of the process was successfully shown. The experiments included (a) determination of background thermal decomposition gases, (b) the electrolysis of a sodium-carbonate-only smelt to show that sodium oxide can be electrochemically produced, and (c) electrolysis of a synthetic smelt containing 80 mole% Na2-CO3 and 20 mole% Na2-S. The experiments show that sodium hydroxide (NaOH) was produced by the electrochemical reduction of sodium carbonate to sodium oxide in the molten state. In the experiment containing sodium sulfide, there was formation of less than 5 mole% of polysulfide. Energy savings on the order of 500,000 BTU per ton of kraft pulp produced are estimated, based on the energy used by the mill. Operating costs are estimated to be currently similar to conventional processing. However, price increases of fossil fuels and increased co-generation of electricity in the mill will give the electrolytical process significant cost advantages.

  5. Sub-grain scale mineralogy of Hanford sand after reaction with caustic tank wastes

    Science.gov (United States)

    Crandell, L. E.; Peters, C. A.; Um, W.; Lindquist, W.

    2010-12-01

    Reactions of caustic tank waste with vadose-zone sediments at the DOE Hanford, WA site cause dissolution of quartz and aluminosilicate minerals and precipitation of secondary minerals, sodalite and cancrinite. In this study, Hanford sediments from reactive column experiments were examined using 2-D imaging technologies. Mineralogy was examined at the sub-grain scale through image analysis of SEM backscattered electron (BSE) images supplemented with elemental mapping from energy-dispersive X-ray spectroscopy (EDS). The thin sections were made from cross-sections of epoxied sediments in the experimental columns, before and after reaction with simulated tank waste leachate. The image analysis method developed for this work identifies the important minerals and quantifies their accessibility to pore fluids, information that may be used to improve reactive transport modeling of water-rock reactions. Current reactive transport models use mineralogical information obtained through X-ray diffraction (XRD) analysis of crushed samples. Such analysis provides reliable information on the relative quantities of minerals present in macroscopic samples. However, the absence of information on sub-grain scale mineralogy may lead to erroneous interpretation in the context of reactive transport. Preliminary findings indicate the presence of grain inclusions and secondary mineral coatings which may significantly impact the accessibility of minerals to pore waters and thus alter the predicted water -rock reactions.

  6. MODULAR CAUSTIC SIDE SOLVENT EXTRACTION UNIT GAMMA MONITORS SYSTEM FINAL REPORT

    Energy Technology Data Exchange (ETDEWEB)

    Casella, V

    2007-06-25

    The Department of Energy (DOE) selected Caustic-Side Solvent Extraction (CSSX) as the preferred technology for the removal of radioactive cesium from High-Level Waste (HLW) at the Savannah River Site (SRS). Before the full-scale Salt Waste Processing Facility (SWPF) becomes operational, the liquid Waste Organization (LWO) plans to process a portion of dissolved saltcake waste through a Modular CSSX Unit (MCU). This work was derived from Technical Task Request SP-TTR-2004-00013, ''Gamma Monitor for MCU.'' The deliverables for this task are the hardware and software for the gamma monitors and a report summarizing the testing and acceptance of this equipment for use in the MCU. Revision of this report is a deliverable in Technical Task Report SP-TTR-2006-00010, ''NaI Shield Box Testing.'' Gamma-ray monitors were developed to: {lg_bullet} Measure the Cs-137 concentration in the decontaminated salt solution before entering the DSS (Decontaminated Salt Solution) Hold Tank, {lg_bullet} Measure the Cs-137 concentration in the strip effluent before entering the Strip Effluent Hold Tank, {lg_bullet} Verify proper operation of the solvent extraction system by verifying material balance within the process (The DSS Hold Tank Cs-137 concentration will be very low and the Cs-137 concentration in the Strip Effluent Hold Tank will be approximately fifteen times higher than the Cs-137 concentration in the Feed Tank.)

  7. UV-catalytic treatment of spent caustic from ethene plant with hydrogen peroxide and ozone oxidation

    Institute of Scientific and Technical Information of China (English)

    YU Zheng-zhe; SUN De-zhi; LI Chang-hai; SHI Peng-fei; DUAN Xiao-dong; SUN Guo-rong; LIU Jun-xin

    2004-01-01

    The performance of UV/H2O2, UV/O3 and UV/H2O2/O3 oxidation systems for treating spent caustic froman ethylene plant was investigated. In UV/H2O2 system, with the increase of H2O2 dosage, removal efficiencies ofCOD and the ratio of biochemical oxygen demand(BOD) to chemical oxygen demand(COD) of the effluent wereincreased and a better performance was obtained than the H2O2 system alone. In UV/H2O2 system, removalefficiency of COD reach 68% under the optimum condition, and BOD/COD ratio was significantly increased from0.22 to 0.52. In UV/O3 system, with the increase of O3 dosage, removal efficiency of COD and BOD/COD ratiowere increased, and a better performance was obtained than the O3 system alone. Under the optimum condition,removal efficiency of COD was 54%, and BOD/COD ratio was significantly increased from 0.22 to 0.48. In UV/H2O2/O3 system, COD removal efficiency was found to be 22.0% higher than UV/O3 system.

  8. Electrochemical studies on stress corrosion cracking of incoloy-800 in caustic solution. Part II: Precracking samples

    Directory of Open Access Journals (Sweden)

    Dinu Alice

    2006-01-01

    Full Text Available Stress corrosion cracking (SCC in a caustic medium may affect the secondary circuit tubing of a CANDU NPP cooled with river water, due to an accidental formation of a concentrated alkaline environment in the areas with restricted circulation, as a result of a leakage of cooling water from the condenser. To evaluate the susceptibility of Incoloy-800 (used to manufacture steam generator tubes for CANDU NPP to SCC, some accelerated corrosion tests were conducted in an alkaline solution (10% NaOH, pH = 13. These experiments were performed at ambient temperature and 85 °C. We used the potentiodynamic method and the potentiostatic method, simultaneously monitoring the variation of the open circuit potential during a time period (E corr/time curve. The C-ring method was used to stress the samples. In order to create stress concentrations, mechanical precracks with a depth of 100 or 250 μm were made on the outer side of the C-rings. Experimental results showed that the stressed samples were more susceptible to SCC than the unstressed samples whereas the increase in temperature and crack depth lead to an increase in SCC susceptibility. Incipient micro cracks of a depth of 30 μm were detected in the area of the highest peak of the mechanical precrack.

  9. Biofilm forming and leaching mechanism during bioleaching chalcopyrite by Thiobacillus ferrooxidans

    Institute of Scientific and Technical Information of China (English)

    傅建华; 胡岳华; 邱冠周; 柳建设; 徐竞

    2004-01-01

    The mechanism of attachment and leaching of thiobacillus ferrooxcidans (T. f. ) on chalcopyrite were studied. The shaking flasks with bacteria were observed by SEM. The process of T. f attached to the surface of the mineral sample and the biofilm forming were described. The promoting role of the biofilm for bioleaching was discussed. The existence of Fe2+ in the exopolysaccharide layer of T. f was demonstrated by EM(electronic microscope)cell-chemistry analysis. These results show that under the proper growth condition of bacteria, bioleaching of chalcopyrite results in the formation of complete biofilm after 2 - 3 weeks. There are iron ions in the outer layer polymer of T. f. , which provides the micro-environment for themselves, and can guaruntee the energy needed for the bacteria growth in the biofilm. At the same time, Fe3+ ions produced oxidize sulfide which brings about the increase of both growth rate of the bacterial and leaching rate of sulfide minerals.

  10. Nitrate Leaching From Grain Maize After Different Tillage Methods and Long/Short Term Cover Cropping

    DEFF Research Database (Denmark)

    Hansen, Elly Møller

    trial initiated in 1968 on a coarse sandy soil. The previous trial included spring sown crops undersown (with or without) perennial ryegrass (Lolium perenne L.) as cover crop, two N-rates (90 and 120 kg N ha-1) and different tillage methods (shallow tillage and ploughing autumn or spring). With maize......, each previous long-term treatment with soil tillage and cover crop was sub-divided into two, one with perennial ryegrass as cover crop and one without cover crop. The maize was sown in 2009 and 2010 and fertilized with 140 kg N ha-1. The objectives were to determine the effects on leaching of i......) previous history of long-term cover cropping, ii) soil tillage methods, iii) N rates and iv) present short-term use of cover cropping in maize. Preliminary results from 2009 – 2011 suggest that leaching after a history of cover cropping tended to be higher than after no history of cover cropping...

  11. Organic ligands influence leaching kinetics of fixated FGD material

    Energy Technology Data Exchange (ETDEWEB)

    Chin-Min Cheng; Yu Sik Hwang; John J. Lenhart; Harold W. Walker [Ohio State University, Columbus, OH (United States). Department of Civil and Environmental Engineering and Geodetic Science

    2008-10-15

    The presence of organic ligands, including oxalate, citrate, maleate and Pahokee peat humic acid (PPHA), influenced the leaching kinetics of fixated flue gas desulfurization (FGD) material in acidic solution (pH 2.9-5.0). In the presence of oxalate, the leaching was inhibited at all pH values examined. XRD and SEM analyses demonstrated that formation of a calcium oxalate mineral phase on the fixated FGD material surface created a surface layer which reduced the extent of leaching. Maleate and PPHA inhibited leaching at pH 2.9, but either promoted, inhibited, or had no effect on leaching, depending on the particular element, at pH 5.0. ATR-FTIR analysis indicated maleate and PPHA formed both inner- and outer-spherically bound species at pH 2.9, whereas at pH 5.0 only outer-sphere complexes seemed evident. These surface species likely inhibited the leaching process at pH 2.9 through a surface blocking mechanism. At pH 5.0, the ligand surface complexes either promoted or inhibited leaching, depending on the element, through a combination of direct and indirect mechanisms. Citrate significantly promoted the leaching process at all pH values examined. 43 refs., 6 figs., 3 tabs.

  12. Leaching of polyphase nuclear waste ceramics: microstructural and phase characterization

    International Nuclear Information System (INIS)

    Alumina-based ceramics are potential materials for storage of nuclear wastes. Static leach tests conducted on ceramic monoliths in deionized water, in simulated silicate, and in brine groundwaters, conforming to Materials Characterization Center standards and an accelerated, microscopic leach test, were used to identify the processes. Dissolution and formation of surface passivation layers are discussed. 40 refs

  13. Nitrate leaching and pesticide use in energy crops

    DEFF Research Database (Denmark)

    Jørgensen, Uffe

    2006-01-01

    Nitrate leaching measured below willow and miscanthus is very low from the established crops. Pesticide use in energy crops is low as well.......Nitrate leaching measured below willow and miscanthus is very low from the established crops. Pesticide use in energy crops is low as well....

  14. Accelerated Leach Test(s) Program: Annual report

    Energy Technology Data Exchange (ETDEWEB)

    Dougherty, D.R.; Pietrzak, R.F.; Fuhrmann, M.; Colombo, P.

    1986-09-01

    A computerized data base of LLW leaching data has been developed. Long-term tests on portland cement, bitumen and vinyl ester-styrene (VES) polymer waste forms containing simulated wastes are underway which are designed to identify and evaluate factors that accelerate leaching without changing the mechanisms.

  15. Manual of acid in situ leach uranium mining technology

    International Nuclear Information System (INIS)

    In situ leaching (ISL) technology recovers uranium using two alternative chemical leaching systems - acid and alkaline. This report brings together information from several technical disciplines that are an essential part of ISL technology. They include uranium geology, geohydrology, chemistry as well as reservoir engineering and process engineering. This report provides an extensive description of acid ISL uranium mining technology

  16. Pesticide leaching in macroporous clay soils: field experiment and modeling

    NARCIS (Netherlands)

    Scorza Júnior, R.P.

    2002-01-01

    Keywords : pesticide leaching, macropores, preferential flow, preferential transport, cracked clay soil, pesticide leaching models, groundwater contamination, inverse modeling, bentazone and imidacloprid. The presence of macropores (i.e. shrinkage c

  17. PLEASE: a simple model to determine P losses by leaching

    NARCIS (Netherlands)

    Schoumans, O.F.; Salm, van der C.; Groenendijk, P.

    2013-01-01

    Non-point phosphorus (P) loss from agricultural land to streams is caused mainly by overland flow and leaching. In many countries P-index methods are used to identify areas at risk of P loss to streams. In flat areas with shallow groundwater levels, where losses by leaching are important, these inde

  18. Leaching of actinide-doped nuclear waste glass in a tuff-dominated system

    International Nuclear Information System (INIS)

    A laboratory leaching test has been performed as part of a project to evaluate the suitability of tuff rocks at Yucca Mountain, Nevada, as a site for a high-level nuclear waste repository. Glass samples were placed in water inside tuff vessels, and then the tuff vessels were placed in water inside Teflon containers. Glass-component leach rates and migration through the tuff were measured for samples of the ATM-8 actinide glass, which is a PNL 76-68 based glass doped with low levels of 99Tc, 237Np, 238U, and 239Pu to simulate wastes. Disc samples of this glass were leached at 900C for 30, 90, and 183 days inside tuff vessels using a natural groundwater (J-13 well-water) as the leachant. At the end of each leaching interval, the J-13 water present inside and outside the rock vessel was analyzed for glass components in solutions. Boron, molybdenum, and technetium appear to migrate through the rock at rates that depend on the porosity of each vessel and the time. The actinide elements were found only in the inner leachate. Normalized elemental mass loss values for boron, molybdenum, and technetium were calculated using concentrations of the inner and outer leachates and assuming a negligible retention on the rock. The maximum normalized release was 2.3 g/m2 for technetium. Boron, molybdenum, technetium, and neptunium were released linearly with respect to each other, with boron and molybdenum released at about 85% of the technetium rate, and neptunium at 5 to 10% of the technetium rate. Plutonium was found at low levels in the inner leachate but was strongly sorbed on the steel and Teflon supports. Neptunium was sorbed to a lesser extent. 8 refs., 6 figs., 6 tabs

  19. Reduction in nitrate leaching from a concrete waste form by using waterproofing admixture additions

    International Nuclear Information System (INIS)

    Admixture additions of active lime and tricalcium aluminate reduced leach rate about 20% during a seven-day test of a concrete waste form containing a nitrate bearing, aqueous waste. CaO was 5% more effective and, in SEM examination, appeared to hydrate to CaOH which expanded in the concrete pores and blocked water movement. Over time, this compound appeared to dissolve slowly in the water, and the barrier layer it produced slowly receded into the specimen interior

  20. Thermal And Spectroscopic Analyses Of Next Generation Caustic Side Solvent Extraction Solvent Contacted With 3, 8, And 16 Molar Nitric Acid

    Energy Technology Data Exchange (ETDEWEB)

    Fondeur, F. F.; Fink, S. D.

    2011-12-07

    A new solvent system referred to as Next Generation Solvent or NGS, has been developed at Oak Ridge National Laboratory for the removal of cesium from alkaline solutions in the Caustic Side Solvent Extraction process. The NGS is proposed for deployment at MCU{sup a} and at the Salt Waste Processing Facility. This work investigated the chemical compatibility between NGS and 16 M, 8 M, and 3 M nitric acid from contact that may occur in handling of analytical samples from MCU or, for 3 M acid, which may occur during contactor cleaning operations at MCU. This work shows that reactions occurred between NGS components and the high molarity nitric acid. Reaction rates are much faster in 8 M and 16 M nitric acid than in 3 M nitric acid. In the case of 16 M and 8 M nitric acid, the nitric acid reacts with the extractant to produce initially organo-nitrate species. The reaction also releases soluble fluorinated alcohols such as tetrafluoropropanol. With longer contact time, the modifier reacts to produce a tarry substance with evolved gases (NO{sub x} and possibly CO). Calorimetric analysis of the reaction product mixtures revealed that the organo-nitrates reaction products are not explosive and will not deflagrate.