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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. 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.

  4. Washing and caustic leaching of Hanford tank sludge: Results of FY 1997 studies

    Energy Technology Data Exchange (ETDEWEB)

    Lumetta, G.J.; Burgeson, I.E.; Wagner, M.J.; Liu, J.; Chen, Y.L.

    1997-08-01

    The current plan for remediating the Hanford tank farms consists of waste retrieval, pretreatment, treatment (immobilization), and disposal. The tank wastes will be partitioned into high-level and low-level fractions. 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 vitrification and geologic disposal, pretreatment processes will be implemented to reduce the volume of immobilized high-level waste (IHLW). Caustic leaching (sometimes referred to as enhanced sludge washing or ESW) represents the baseline method for pretreating Hanford tank sludges. Caustic leaching is expected to remove a large fraction of the Al, which is present in large quantities in Hanford tank sludges. A significant portion of the P is also expected to be removed from the sludge by metathesis of water-insoluble metal phosphates to insoluble hydroxides and soluble Na{sub 3}PO{sub 4}. Similar metathesis reactions can occur for insoluble sulfate salts, allowing the removal of sulfate from the HLW stream. This report describes the sludge washing and caustic leaching tests performed at the Pacific Northwest National Laboratory in FY 1996. The sludges used in this study were taken from Hanford tanks AN-104, BY-108, S-101, and S-111.

  5. 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.

    1997-12-31

    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.

  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. 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

  8. 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.

  9. 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.

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

    Energy Technology Data Exchange (ETDEWEB)

    Rapko, B.M.; Lumetta, G.J.; Wagner, M.J.

    1995-08-11

    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).

  11. 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.

  12. Chalcopyrite leaching: The rate controlling factors

    Science.gov (United States)

    Li, J.; Kawashima, N.; Kaplun, K.; Absolon, V. J.; Gerson, A. R.

    2010-05-01

    The processes that determine the rate of chalcopyrite leaching are central to understanding how chalcopyrite (CuFeS 2) behaves under the environmentally adverse conditions of acid rock drainage. To this end the effect of the acid anion on chalcopyrite leach rates using a variety of acidic media (H 2SO 4, HClO 4, HCl and H 2SO 4 with 0.25 M NaCl) under carefully controlled solution conditions (pH 1 and 2, Eh 750 mV (SHE) and 75 °C) has been examined. These conditions have been chosen to enable sufficient leach rates for accurate experimental determination and to compare to the previous mechanistic analysis carried out by Harmer et al. (2006). Extensive surface analysis of leach residues demonstrated that variations in the surface speciation could not be responsible for the observed variations in leach rate. The rate of Cu release, however, was found to be first order with respect to Fe 3+ activity and inversely proportional with respect to H + activity to the power of 0.7: {1}/{S}{dC}/{dt}=(2.0±0.2){a}/{aH0.7} where S is the relative surface area, C is concentration of Cu in the solution (M), t is the time (h), 2.0 is the rate constant (M 0.7 h -1) and a and a are Fe 3+ and H + activities, respectively (M). The rate model was further validated against additional leaches carried out in H 2SO 4 media with the initial addition of Fe 3+ (8 mM as Fe 2(SO 4) 3) at 75 °C under various pH and Eh regimes. The only condition under which this rate model was found not to hold was at simultaneously low a and high a, that is at pH 1 and a<5×10-5M, where the concentration of dissolved O 2 may be leach rate determining.

  13. 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.

  14. 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.

  15. [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.

  16. 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)

  17. 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

  18. 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.

  19. Increasing flux rate to shorten leaching period and ramp-up production

    Science.gov (United States)

    Ngantung, Billy; Agustin, Riska; Ravi'i

    2017-01-01

    J Resources Bolaang Mongondow (JBRM) has operated a dynamic heap leach in its Bakan Gold Mine since late 2013. After successfully surpassing its name plate capacity of 2.6 MT/annum in 2014, the clayey and transition ore become the next operational challenge. The presence of transition and clayey ore requires longer leaching period, hence reducing the leach pad capacity which then caused reduced production. Maintaining or even increasing production with such longer leaching ore types can be done by expanding the leach pad area which means an additional capital investment, and/or shortening the leaching cycle which compromise a portion of gold extraction. JBRM has been successfully increasing the leach pad production from 2.6 MT/annum to 3.8 MT/annum, whilst improving the gold extraction from around 70% to around 80%. This was achieved by managing the operation of the leach pad which is shortening the leach cycle by identifying and combining the optimal flux rate application versus the tonne processed in each cell, at no capital investment for expanding the cell capacity.

  20. Caustics for Spherical Waves

    CERN Document Server

    de Rham, Claudia

    2016-01-01

    We study the development of caustics in shift-symmetric scalar field theories by focusing on simple waves with an $SO(p)$-symmetry in an arbitrary number of space dimensions. We show that the Galileon and the DBI-Galileon naturally emerge as the unique set of caustic-free theories, highlighting a link between the caustic-free condition for simple $SO(p)$-waves and the existence of either a global galilean symmetry or a global relativistic galilean symmetry.

  1. 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.

  2. Space-time caustics

    Directory of Open Access Journals (Sweden)

    Arthur D. Gorman

    1986-01-01

    Full Text Available The Lagrange manifold (WKB formalism enables the determination of the asymptotic series solution of linear differential equations modelling wave propagation in spatially inhomogeneous media at caustic (turning points. Here the formalism is adapted to determine a class of asymptotic solutions at caustic points for those equations modelling wave propagation in media with both spatial and temporal inhomogeneities. The analogous Schrodinger equation is also considered.

  3. 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.

  4. Effect of irrigation and winery waste compost rates in nitrate leaching in vulnerable zones

    Science.gov (United States)

    Requejo, Maria Isabel; Castellanos, Maria Teresa; Villena, Raquel; Ribas, Francisco; Jesús Cabello, Maria; Arce, Augusto; Cartagena, Maria Carmen

    2013-04-01

    The winery industry is widespread in Spain (3,610,000 tonnes of wine in 2010 (FAO, 2010)), and generates wastes characterized by a high content of organic matter, a notable content in macronutrients and low heavy-metals. These organic wastes could be used for agricultural purposes after a correct stabilization process (e.g. composting).The addition of these organic wastes requires a correct management, especially on semiarid cropped areas of central Spain where environmental degradation of water supplies with high N loads is observed. An integrated optimization of both applied compost dose and amount of irrigation is important to ensure optimum yields and minimum nitrate leaching losses. The purpose of this work was to study the effect of the application of winery waste compost as fertilizer in a melon crop cultivated with different drip irrigation rates. The field experiment was carried out in Ciudad Real, designated "vulnerable zone" by the "Nitrates Directive" 91/676/CEE. Melon crop has been traditionally cultivated in this area with high inputs of water and fertilizers, but no antecedents of application of winery wastes are known. Beside the control treatment (D0), three doses of compost were applied: 6.7 (D1), 13.3 (D2) and 20 T/ha(D3).Irrigation treatments consisted of applying a 100% ETc and an excess irrigation of 120% ETc. The soil was a shallow sandy-loam (Petrocalcic Palexeralfs), with 0.6 m depth and a discontinuous petrocalcic horizon between 0.6 and 0.7 m. Drainage and nitrate concentration on the soil solution were measured weekly to determine N leached during the crop period. Crop yield was also followed by harvesting plots when a significant number of fruits were fully matured. A comparison between nitrate leached and crop production among different treatments and irrigation rates are presented. Acknowledgements: This project has been supported by INIA-RTA2010-00110-C03-01.

  5. 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.

  6. Caustic Recycling Pilot Unit to Separate Sodium from LLW at Hanford Site - 12279

    Energy Technology Data Exchange (ETDEWEB)

    Pendleton, Justin; Bhavaraju, Sai; Priday, George; Desai, Aditya; Duffey, Kean; Balagopal, Shekar [Ceramatec Inc., Salt Lake City, UT 84119 (United States)

    2012-07-01

    As part of the Department of Energy (DOE) sponsored Advanced Remediation Technologies initiative, a scheme was developed to combine Continuous Sludge Leaching (CSL), Near-Tank Cesium Removal (NTCR), and Caustic Recycling Unit (CRU) using Ceramatec technology, into a single system known as the Pilot Near-Tank Treatment System (PNTTS). The Cesium (Cs) decontaminated effluent from the NTCR process will be sent to the caustic recycle process for recovery of the caustic which will be reused in another cycle of caustic leaching in the CSL process. Such an integrated mobile technology demonstration will give DOE the option to insert this process for sodium management at various sites in Hanford, and will minimize the addition of further sodium into the waste tanks. This allows for recycling of the caustic used to remove aluminum during sludge washing as a pretreatment step in the vitrification of radioactive waste which will decrease the Low Level Waste (LLW) volume by as much as 39%. The CRU pilot process was designed to recycle sodium in the form of pure sodium hydroxide. The basis for the design of the 1/4 scale pilot caustic recycling unit was to demonstrate the efficient operation of a larger scale system to recycle caustic from the NTCR effluent stream from the Parsons process. The CRU was designed to process 0.28 liter/minute of NTCR effluent, and generate 10 M concentration of 'usable' sodium hydroxide. The proposed process operates at 40 deg. C to provide additional aluminum solubility and then recover the sodium hydroxide to the point where the aluminum is saturated at 40 deg. C. A system was developed to safely separate and vent the gases generated during operation of the CRU with the production of 10 M sodium hydroxide. Caustic was produced at a rate between 1.9 to 9.3 kg/hr. The CRU was located inside an ISO container to allow for moving of the unit close to tank locations to process the LLW stream. Actual tests were conducted with the NTCR effluent

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. 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

  12. 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.

  13. Rate of constitutive innate humoral immune development in Leach's storm petrel (Oceanodroma leucorhoa) chicks is negatively correlated with growth rate

    NARCIS (Netherlands)

    Mauck, R.A.; Matson, K.D.; Philipsborn, J.; Ricklefs, R.E.

    2005-01-01

    1 Using a simple technique for assessing constitutive innate immune function recently adapted for use in wild populations, we characterize changes in avian immune system development by repeated measurements of individuals over the period of nestling growth in a wild population of Leach's Storm-Petre

  14. 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

  15. 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.

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  20. 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

  1. In-situ caustic generation from sewage: the impact of caustic strength and sewage composition.

    Science.gov (United States)

    Pikaar, Ilje; Rozendal, René A; Rabaey, Korneel; Yuan, Zhiguo

    2013-10-01

    Periodic caustic dosage is a commonly used method by the water industry to elevate pH levels and deactivate sewer biofilms responsible for hydrogen sulfide generation. Caustic (NaOH) can be generated in-situ from sewage using a divided electrochemical cell, which avoids the need for transport, handling and storage of concentrated caustic solutions. In this study, we investigated the impact of caustic strength in the cathode compartment and the impact of sodium concentration in sewage on the Coulombic efficiency (CE) for caustic generation. The CE was found to be independent of the caustic strength produced in the range of up to ~3 wt%. Results showed that a caustic solution of ~3 wt% could be produced directly from sewage at a CE of up to 75 ± 0.5%. The sodium concentration in sewage had a significant impact on the CE for caustic generation as well as on the energy requirements of the system, with a higher sodium concentration leading to a higher CE and lower energy consumption. The proton, calcium, magnesium and ammonium concentrations in sewage affected the CE for caustic generation, especially at low sodium concentrations. Economical assessment based on the experimental results indicated that sulfide control in sewers using electrochemically-generated caustic from sewage is an economically attractive strategy.

  2. 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 by weight sodium hydroxide in aqueous solution. The amount of caustic soda used shall be such...

  3. Caustic ingestion and esophageal function

    Energy Technology Data Exchange (ETDEWEB)

    Cadranel, S.; Di Lorenzo, C.; Rodesch, P.; Piepsz, A.; Ham, H.R. (Children University Hospital, Brussels (Belgium))

    1990-02-01

    The aim of the present study was to investigate esophageal motor function by means of krypton-81m esophageal transit scintigraphy and to compare the results with the functional and morphological data obtained by means of triple lumen manometry and endoscopy. In acute and subacute stages of the disease, all clinical, anatomical, and functional parameters were in good agreement, revealing significant impairment. In chronic stages, the severity of the dysphagia was not correlated to the importance of the residual stenosis. Conversely, 81mKr esophageal transit and manometric's findings were in good agreement with the clinical symptoms, during the entire follow-up period ranging between 3 months to 7 years. The 81mKr test is undoubtedly the easiest and probably the most physiological technique currently available for long-term functional evaluation of caustic esophagitis.

  4. Caustic Soda Will Be Oversupply in 2007

    Institute of Scientific and Technical Information of China (English)

    Yao Liqin

    2007-01-01

    @@ Rapid output increase There are more than 220 caustic soda producers in China today. At the end of 2006 the capacity of caustic soda in China was 17.61 million t/a. The output of caustic soda was 15.118 million tons in 2006, an increase of 19.0% over 2005 and 1.331 million tons were exported, an increase of 55.8%. Production increased fastest in Northwest China, with growth 51.9% faster than 2005. The output in East China grew 22.9% and 22.3% in Southwest China, both higher than the national average level.

  5. Biochar applied with appropriate rates can reduce N leaching, keep N retention and not increase NH3 volatilization in a coastal saline soil.

    Science.gov (United States)

    Sun, Haijun; Lu, Haiying; Chu, Lei; Shao, Hongbo; Shi, Weiming

    2017-01-01

    The impacts of biochar addition on nitrogen (N) leaching, (ammonia) NH3 volatilization from coastal saline soils are not well understood. In this soil column study, the effects of wheat straw biochar application at rates of 0.5%, 1%, 2% and 4% by weight to a coastal saline soil on N leaching, NH3 volatilization, soil pH and N retention were investigated. Results showed that 0.5% and 1% biochar amendments reduce the NH4(+)-N, NO3(-)-N and total N concentrations of leachate and thereby significantly decrease their cumulative lost loads by 11.6-24.0%, 13.2-29.7%, and 14.6-26.0%, respectively, in compared with the control. The biochar-induced soil N leaching mitigation efficiency was weakened when the biochar application rates increased to 2% and 4%. However, the impact of biochar addition on cumulative NH3 volatilizations were negative and significantly 25.6-53.6% higher NH3 volatilizations in soils with 2% and 4% biochar amended than control were detected, which was mainly attributed to the averaged 0.53-0.88units higher soil pH as results of biochar addition. On average, the total N concentrations of soil were kept same with 1.01-1.06gkg(-1) under control and biochar treatments. Therefore, biochar application to the coastal saline soils with appropriate rates (i.e., 0.5% and 1% in current study) can reduce N leaching, keep soil N retention, and not increase NH3 volatilization, which was beneficial for sustainable use of saline soils.

  6. 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.

  7. 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.

  8. Pigging ends freezeups in caustic piping system

    Energy Technology Data Exchange (ETDEWEB)

    Gros, R.; Gaines, A.

    1985-03-01

    Convent Chemical Corporation in Convent, LA produces and ships bulk quantities of chlorine and caustic soda (NaOH). The caustic soda is available in various grades, including a 50% aqueous solution that freezes at 56/sup 0/F. An extensive network of chemical-resistant polypropylene-lined steel pipe (without heat tracing) is used to transfer the caustic soda from the production area to storage tanks and to the loading facilities for tank trucks, rail tank cars and barges. A sudden drop in ambient temperature can cause freezeup of the caustic transfer pipes which may result in downtime of as much as a week. Convent plant engineers designed a pigging system for the outdoor caustic transfer lines in the tank farm and to the loading stations. The patented design pig, (internal pipeline cleaner) consists of a flexible, bullet-shaped cylinder of chemical-resistant polyurethane foam with strips of urethane rubber on the surface, or with a solid coating of the tough material. Fluid or gas pressure on the sealed concave base propels the flexible pig through the pipe, valves, elbows, and other fittings, and material ahead of the pig is discharged into an appropriate receiver. The pigging system has eliminated the caustic freezing and plugging problems since it was installed in the summer of 1981. The flexible pig, propelled by 80 psi air, is used to clear the pipelines whenever caustic is transferred during the winter months. The air-propelled pig is designed and sized to easily pass through restrictions in the piping system, such as reduced port plug valves, but was once stuck when it reached a section of pipe that had collapsed. A pig containing the Cobalt 60 nuclear element was inserted into the line to quickly locate the stuck pig with the Geiger counter. The faulty section of pipe was replaced with a new polypropylene lined spool piece.

  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. 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%.

  13. Zinc leaching from tire crumb rubber.

    Science.gov (United States)

    Rhodes, Emily P; Ren, Zhiyong; Mays, David C

    2012-12-04

    Because tires contain approximately 1-2% zinc by weight, zinc leaching is an environmental concern associated with civil engineering applications of tire crumb rubber. An assessment of zinc leaching data from 14 studies in the published literature indicates that increasing zinc leaching is associated with lower pH and longer leaching times, but the data display a wide range of zinc concentrations, and do not address the effect of crumb rubber size or the dynamics of zinc leaching during flow through porous crumb rubber. The present study was undertaken to investigate the effect of crumb rubber size using the synthetic precipitation leaching procedure (SPLP), the effect of exposure time using quiescent batch leaching tests, and the dynamics of zinc leaching using column tests. Results indicate that zinc leaching from tire crumb rubber increases with smaller crumb rubber and longer exposure time. Results from SPLP and quiescent batch leaching tests are interpreted with a single-parameter leaching model that predicts a constant rate of zinc leaching up to 96 h. Breakthrough curves from column tests displayed an initial pulse of elevated zinc concentration (~3 mg/L) before settling down to a steady-state value (~0.2 mg/L), and were modeled with the software package HYDRUS-1D. Washing crumb rubber reduces this initial pulse but does not change the steady-state value. No leaching experiment significantly reduced the reservoir of zinc in the crumb rubber.

  14. Modeling the effects of different N fertilizer rates on N2O emissions and nitrate leaching from arable soils in Korea

    Science.gov (United States)

    Kim, Y.; Berger, S.; Tenhunen, J. D.; Gebauer, G.; Kiese, R.

    2012-12-01

    Process-based biogeochemical models can be used to predict the impact of various agricultural management practices on plant nitrogen use efficiency and nitrogen losses to the environment such as greenhouse gas emissions and nitrate leaching by analyzing the interactions between management practices, primary drivers such as climate, soil properties, crop types, etc., and biogeochemical reactions. In this study we applied the Landscape-DNDC model, which combines and uniforms functions of the agricultural-DNDC and the Forest-DNDC for simulation of C and N turnover, GHG emissions, nitrate leaching, and plant growth for a Korean arable field cultivated with radish (Raphanus sativus L.). The annual average temperature is app. 8.5°C and the annual precipitation is app. 1,500 mm. According to farmers practice the study field received a basal fertilizer application of app. 200 kg N ha-1 before setting up four fertilizer treatments i.e. additionally 50, 150, 250 and 350 kg N ha-1. All N treatment plots were tilled a week after application of specific N fertilizer in order to make row and interrow. Just before radish seeding rows were covered with black plastic mulch which was removed after harvest. In spite the widespread usage of black mulch in Korea or even Asia; so far biogeochemical models do not consider impacts of mulch on soil environmental conditions and soil biogeochemistry. Based on field measurements we adjusted input information and used only half of the annual precipitation and the maximum temperature for simulation of row conditions, whereas the actual weather data were used for the interrow simulations. Simulated N2O emissions agreed well with measurements; however peak emissions after fertilization were slightly underestimated in row and interrow. Annual N2O emissions of the fertilizer treatments increased with increasing fertilization rates from around 1.5 to 3 kg N ha-1 in the row and lower emissions of app. 1.5 kg N ha-1 (for all N treatments) in the

  15. Comparison of toxicity and release rates of Cu and Zn from anti-fouling paints leached in natural and artificial brackish seawater.

    Science.gov (United States)

    Ytreberg, Erik; Karlsson, Jenny; Eklund, Britta

    2010-05-15

    Biocide-containing anti-fouling paints are regulated and approved according to the added active ingredients, such as Cu. Biocide-free paints are considered to be less environmentally damaging and do not need an approval. Zn, a common ingredient in paints with the potential of causing adverse effects has received only minor attention. Laboratory experiments were conducted in artificial brackish seawater (ASW) and natural brackish seawater (NSW) to quantify release rates of Cu and Zn from biocide-containing and biocide-free labeled eroding anti-fouling paints used on commercial vessels as well as leisure boats. In addition, organisms from three trophic levels, the crustacean Nitocra spinipes, the macroalga Ceramium tenuicorne and the bacteria Vibrio fischeri, were exposed to Cu and Zn to determine the toxicity of these metals. The release rate of Cu in NSW was higher from the paints for professional use (3.2-3.6 microg cm(-)(2)d(-1)) than from the biocide leaching leisure boat paint (1.1 microg cm(-)(2)d(-1)). Biocide-free paints did leach considerably more Zn (4.4-8.2 microg cm(-)(2)d(-1)) than biocide-containing leisure boat paint (3.0 microg cm(-)(2)d(-1)) and ship paints (0.7-2.0 microg cm(-)(2)d(-1)). In ASW the release rates of both metals were notably higher than in NSW for most tested paints. The macroalga was the most sensitive species to both Cu (EC(50)=6.4 microg l(-1)) and Zn (EC(50)=25 microg l(-1)) compared to the crustacean (Cu, LC(50)=2000 microg l(-1) Zn, LC(50)=890 microg l(-1)), and the bacteria (Cu, EC(50)=800 microg l(-1) and Zn, EC(50)=2000 microg l(-1)). The results suggest that the amounts of Zn and Cu leached from anti-fouling paints may attain toxic concentrations in areas with high boat density. To fully account for potential ecological risk associated with anti-fouling paints, Zn as well as active ingredients should be considered in the regulatory process.

  16. Results Of Routine Strip Effluent Hold Tank, Decontaminated Salt Solution Hold Tank, Caustic Wash Tank And Caustic Storage Tank Samples From Modular Caustic-Side Solvent Extraction Unit During Macrobatch 6 Operations

    Energy Technology Data Exchange (ETDEWEB)

    Peters, T. B.

    2014-01-02

    Strip Effluent Hold Tank (SEHT), Decontaminated Salt Solution Hold Tank (DSSHT), Caustic Wash Tank (CWT) and Caustic Storage Tank (CST) samples from the Interim Salt Disposition Project (ISDP) Salt Batch (“Macrobatch”) 6 have been analyzed for 238Pu, 90Sr, 137Cs, and by Inductively Coupled Plasma Emission Spectroscopy (ICPES). The Pu, Sr, and Cs results from the current Macrobatch 6 samples are similar to those from comparable samples in previous Macrobatch 5. In addition the SEHT and DSSHT heel samples (i.e. ‘preliminary’) have been analyzed and reported to meet NGS Demonstration Plan requirements. From a bulk chemical point of view, the ICPES results do not vary considerably between this and the previous samples. The titanium results in the DSSHT samples continue to indicate the presence of Ti, when the feed material does not have detectable levels. This most likely indicates that leaching of Ti from MST has increased in ARP at the higher free hydroxide concentrations in the current feed.

  17. 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.

  18. 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...

  19. 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

    the cumulative loss of nitrate to increase significantly. More nitrate was leached after application of slurry because organic nitrogen in the slurry was mineralized. With IN (CAN) the leaching losses of nitrate were in the following order: continuous spring barley undersown with Italian ryegrass

  20. 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.

  1. Extracting Vanadium from Stone Coal by a Cyclic Alkaline Leaching Method

    Science.gov (United States)

    Hu, Kailong; Liu, Xuheng; Li, Qinggang

    2017-01-01

    In order to achieve an efficient and economical approach on extracting vanadium from stone coal, a cyclic alkaline leaching method was studied in this work. The effects of operating parameters, including the NaOH concentration, temperature, reaction time, and liquid-solid ratio, on vanadium leaching efficiency were investigated. Also, we studied the influence of caustic soda dosage on the cyclic leaching process as well as the effect of increasing ionic strength in leachates and wash water. The results show that this method achieved a 51 pct decrease of the dosage of caustic soda under the optimized conditions compared with the single-step alkaline leaching. The average leaching yield of vanadium reached 82.28 pct. The leachates and wash water in each leaching cycle were utilized for the next leaching cycle, achieving the recycling of alkali as well as waste water. During the cyclic process, the volume of water was not increased, which markedly reduces the discharge of waste water and is also beneficial in terms of cost reduction.

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

    Energy Technology Data Exchange (ETDEWEB)

    Katayama, Y.B.

    1979-04-01

    Spent light-water-reactor (LWR) fuels with burnups of 54.5, 28 and 9 MWd/kgU were leach-tested in deionized water at 25/sup 0/C. Fuel burnup has no apparent effect on the calculated leach rates based upon the behavior of /sup 137/Cs and /sup 239 +240/Pu. 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.

  3. Topical mitomycin C can effectively alleviate dysphagia in children with long-segment caustic esophageal strictures.

    Science.gov (United States)

    El-Asmar, K M; Hassan, M A; Abdelkader, H M; Hamza, A F

    2015-07-01

    Caustic ingestion in children and the resulting long esophageal strictures are usually difficult to be managed, and eventually, esophageal replacement was required for cases refractory to frequent dilatation sessions. Topical mitomycin C (MMC) application has been used recently to improve the results of endoscopic dilatation for short esophageal strictures. The study aims to assess the role of MMC application in management of long-segment caustic esophageal strictures. From January 2009 to June December 2013, patients presented with long caustic esophageal stricture (>3 cm in length) were included in this study and subjected to topical MMC application after endoscopic esophageal dilatation on multiple sessions. Regular follow-up and re-evaluation were done. A dysphagia score was used for close follow-up clinically; verification was done radiologically and endoscopically. During the specified follow-up period, 21 patients with long caustic esophageal stricture were subjected to topical MMC application sessions. Clinical, radiological, and endoscopic resolution of strictures occurred in 18 patients (85.7% cure rate). Number of dilatation sessions to achieve resolution of dysphagia was (n = 14.3 ± 5.7) with application of mitomycin two to six times. There was no recurrence in short- and mid-term follow-up. No complications were encountered related to topical MMC application. MMC is a promising agent in management of long-segment caustic esophageal strictures. Long-term follow-up is needed to prove its efficacy and to evaluate potential long-term side-effects of MMC application.

  4. Caustics and Caustic-Diffraction in Laser Shadowgraphy of a Sessile Drop and Identification of Profile Near Contact Line

    Science.gov (United States)

    Zhang, Neng-Li; Chao, David F.

    2003-01-01

    This paper presents an optical method based on the caustics and caustic-difraction in laser shadowgaphy of a sessile drop to identify and estimate the drop profile near the contact line. A parallel laser beam passes through a liquid sessile drop placed on a transparent substrate to produce a shadowgraphic image of the drop on the screen far from the substrate. Along the inflection line of the drop the Gaussian curvature of the wavefront deformed by the drop vanishes, and therefore the inflection line gives caustics in the far field of the wave, which can be seen on the screen. The neighboring light rays at both sides of the inflection line interfere with each other to form interference fringes at the inner side of the caustics. According to the pattern of the caustics, the drop-profile shape can be identified and estimated.

  5. 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

  6. Synthesis and characterization of TiO2 from ilmenite by caustic fusion process for photocatalytic application

    Science.gov (United States)

    Mulyono, J. E.; Soepriyanto, S.

    2017-01-01

    In this research, the use of TiO2 from Indonesian ilmenite will be developed using caustic fusion process and made into photocatalyst product that will be applied for water treatment applications. The research procedures include caustic fusion process involving the mixing of NaOH and ilmenite with a ratio of 1 : 4 at 650°C for 120 minutes. The result from this caustic fusion process, i.e. frit, was then washed with water and followed by acid leaching using sulfuric acid 45% to obtain precursor TiOSO4. This precursor was then hydrolyzed to produce white precipitates in the form of sol TiO(OH)2 which was then condensed for 24 hours. The precipitate was washed and dried before calcined at a temperature of 500°C for 1 hour. X-ray diffraction (XRD) and scanning electron microscopy coupled with energy dispersive X-ray spectroscopy (SEM-EDX) analysis is included to show the phases, morphology and the final composition of the synthesized TiO2 powder. UV-Vis Spectrometry was also used to calculate the band-gap energy and the photocatalytic ability of the synthesized TiO2 in the purification process of rhodamin-B.

  7. 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.

  8. Caustic ingestion-a forensic overview.

    Science.gov (United States)

    Byard, Roger W

    2015-05-01

    The ingestion of corrosive substances may produce severe burns to the upper aerodigestive tract and stomach, particularly if the pH is greater than 12 or less than two. There is a biphasic age grouping with adult cases most often involving self-harm and pediatric cases accidental ingestion. Three cases are reported to demonstrate characteristic features following the ingestion of potassium hydroxide, glacial acetic acid and Lysol(®) , respectively. All deaths were due to the effects of caustic burns to the upper aerodigestive tract, esophagus and stomach with perforation and/or hemorrhage. The extent of injuries in these cases depends on the nature, amount, and concentration of the agent and on the exposure time. A point to note at autopsy is that tissue damage may also occur from postmortem exposure. Typical injuries involve perioral, limb, and trunk burns, with extensive aerodigestive liquefactive/coagulative necrosis causing hemorrhage and perforation.

  9. Photon Differential Splatting for Rendering Caustics

    DEFF Research Database (Denmark)

    Frisvad, Jeppe Revall; Schjøth, Lars; Erleben, Kenny;

    2014-01-01

    We present a photon splatting technique which reduces noise and blur in the rendering of caustics. Blurring of illumination edges is an inherent problem in photon splatting, as each photon is unaware of its neighbours when being splatted. This means that the splat size is usually based...... on heuristics rather than knowledge of the local flux density. We use photon differentials to determine the size and shape of the splats such that we achieve adaptive anisotropic flux density estimation in photon splatting. As compared to previous work that uses photon differentials, we present the first method...... where no photons or beams or differentials need to be stored in a map. We also present improvements in the theory of photon differentials, which give more accurate results and a faster implementation. Our technique has good potential for GPU acceleration, and we limit the number of parameters requiring...

  10. 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.

  11. C-104 high-level waste solids: Washing/leaching and solubility versus temperature studies

    Energy Technology Data Exchange (ETDEWEB)

    GJ Lumetta; DJ Bates; JP Bramson; LP Darnell; OT Farmer III; SK Fiskum; LR Greenwood; FV Hoopes; CZ Soderquist; MJ Steele; RT Steele; MW Urie; JJ Wagner

    2000-05-17

    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 C-104 HLW solids. The objective of this work was to determine the composition of the C-104 solids remaining after washing with 0.01 M NaOH or leaching with 3 M NaOH. Another objective of this test was to determine the solubility of the C-104 solids 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.

  12. K-Area Acid/Caustic Basin groundwater monitoring report. Second quarter 1994

    Energy Technology Data Exchange (ETDEWEB)

    1994-09-01

    During second 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, of the SRS turbidity standard are provided in this report. No constituents exceeded the final PDWS in the KAC wells. Aluminum, iron, and specific conductance exceeded other SRS flagging criteria in one or more of the downgradient wells. Total organic halogens was elevated in upgradient well KAC 3. Groundwater flow direction and rate in the water table beneath the K-Area Acid/Caustic Basin were similar to past quarters.

  13. 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.

  14. Formation of caustics in k-essence and Horndeski theory

    CERN Document Server

    Babichev, Eugeny

    2016-01-01

    We study propagation of waves and appearance of caustics in k-essence and galileon theories. First we show that previously known solutions for travelling waves in k-essence and galileon models correspond to very specific fine-tuned initial conditions. On the contrary, as we demonstrate by the method of characteristics, a generic wave in k-essence ends up with formation of caustics. Finally, we find that any wave solution in pure k-essence is also a solution for a galileon theory with the same k-essence term. Thus in the Horndeski theory formation of caustics is generic. We discuss physical consequences of the caustics formation and possible ways to cure the problem.

  15. 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.

  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. Tracking nanoparticles in an optical microscope using caustics

    Energy Technology Data Exchange (ETDEWEB)

    Patterson, Eann A [Department of Mechanical Engineering, Michigan State University, East Lansing, MI 48824 (United States); Whelan, Maurice P [Nanotechnology and Molecular Imaging Unit, Institute for Health and Consumer Protection, European Commission DG Joint Research Center, 21021 Ispra (Vatican City State, Holy See,) (Italy)

    2008-03-12

    An elegant method is proposed and demonstrated for tracking the location and movement of nanoparticles in an optical microscope using the optical phenomenon of caustics. A simple and reversible adjustment to the microscope generates caustics several orders of magnitude larger than the particles. The method offers a simple and relatively inexpensive method for visualizing such phenomena as the formation of self-assembled monolayers and the interaction of nanoparticles with chemically functionalized surfaces.

  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. Engineering wavefront caustics trajectories in ${\\cal PT}$-symmetric lattices

    CERN Document Server

    Bender, Nicholas; Kottos, Tsampikos

    2015-01-01

    We utilize caustic theory in ${\\cal PT}-$symmetric lattices to design focusing and curved beam dynamics. We show that the gain and loss parameter in these systems provides an addition degree of freedom which allows for the design of the same caustics trajectories with different intensity distribution in the individual waveguides. Moreover we can create aberration-free focal points at any paraxial distance $z_f$, with anomalously large focal intensity.

  20. Nitrate Leaching Management

    Science.gov (United States)

    Nitrate (NO3) leaching is a significant nitrogen (N) loss process for agriculture that must be managed to minimize NO3 enrichment of groundwater and surface waters. Managing NO3 leaching should involve the application of basic principles of understanding the site’s hydrologic cycle, avoiding excess ...

  1. Nitrate Leaching Index

    Science.gov (United States)

    The Nitrate Leaching Index is a rapid assessment tool that evaluates nitrate (NO3) leaching potential based on basic soil and climate information. It is the basis for many nutrient management planning efforts, but it has considerable limitations because of : 1) an oversimplification of the processes...

  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. Critical Curves and Caustics of Triple-lens Models

    Science.gov (United States)

    Daněk, Kamil; Heyrovský, David

    2015-06-01

    Among the 25 planetary systems detected up to now by gravitational microlensing, there are two cases of a star with two planets, and two cases of a binary star with a planet. Other, yet undetected types of triple lenses include triple stars or stars with a planet with a moon. The analysis and interpretation of such events is hindered by the lack of understanding of essential characteristics of triple lenses, such as their critical curves and caustics. We present here analytical and numerical methods for mapping the critical-curve topology and caustic cusp number in the parameter space of n-point-mass lenses. We apply the methods to the analysis of four symmetric triple-lens models, and obtain altogether 9 different critical-curve topologies and 32 caustic structures. While these results include various generic types, they represent just a subset of all possible triple-lens critical curves and caustics. Using the analyzed models, we demonstrate interesting features of triple lenses that do not occur in two-point-mass lenses. We show an example of a lens that cannot be described by the Chang-Refsdal model in the wide limit. In the close limit we demonstrate unusual structures of primary and secondary caustic loops, and explain the conditions for their occurrence. In the planetary limit we find that the presence of a planet may lead to a whole sequence of additional caustic metamorphoses. We show that a pair of planets may change the structure of the primary caustic even when placed far from their resonant position at the Einstein radius.

  4. 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%。

  5. Wavefronts and caustic associated with Durnin’s beams

    Science.gov (United States)

    de Jesús Cabrera-Rosas, Omar; Espíndola-Ramos, Ernesto; Alejandro Juárez-Reyes, Salvador; Julián-Macías, Israel; Ortega-Vidals, Paula; Silva-Ortigoza, Gilberto; Silva-Ortigoza, Ramón; Sosa-Sánchez, Citlalli Teresa

    2017-01-01

    The aim of the present work is to give a geometrical characterization of Durnin’s beams. That is, we compute the wavefronts and caustic associated with the nondiffracting solutions to the scalar wave equation introduced by Durnin. To this end, first we show that in an isotropic optical medium \\psi ({r},t)={{{e}}}{{i}[{k}0S({r})-ω t]} is an exact solution of the wave equation, if and only if, S is a solution of both the eikonal and Laplace equations, then from one and two-parameter families of this type of solution and the superposition principle we define new solutions of the wave equation, in particular we show that the ideal nondiffracting beams are one example of this type of construction in free space. Using this fact, the wavefronts and caustic associated with those beams are computed. We find that their caustic has only one branch, which is invariant under translations along the direction of evolution of the beam. Finally, the Bessel beam of order m is worked out explicitly and we find that it is characterized by wavefronts that are deformations of conical ones and the caustic is an infinite cylinder of radius proportional to m. In the case m = 0, the wavefronts are cones and the caustic degenerates into an infinite line.

  6. Effect of asphericity in caustic mass estimates of galaxy clusters

    CERN Document Server

    Svensmark, Jacob; Hansen, Steen H

    2014-01-01

    The caustic technique of mass estimation of galaxy clusters relies on the assumption of spherical symmetry, which is not always a valid assumption. Here we demonstrate the effect of spatial anisotropy of galaxy clusters on the inferred caustic mass profiles by considering particle data from dark matter N-body simulations. We find a factor of ~3 discrepancy between major and minor axis mass estimates in ellipsoidal clusters within the virial radius Rv, and up to ~5 within 3 Rv. We also find filaments to influence caustic mass estimates at a comparable magnitude. By stacking halos to align their principal axes we find that a line of sight along the major axis overestimates the caustic mass of galaxy clusters, as well as a line of sight along the minor axis underestimates it. The mass discrepancy between the major and minor axis is a factor of 2.47, 2.97 and 3.95 at 1, 2 and 3 Rv for virial masses Mv = [1,2] x 10^{14} Msun/h, and $(30-35)\\%$ larger for Mv > 2 x 10^{14} Msun/h. Furthermore, the caustic mass is ov...

  7. 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.

  8. Caustic ingestion in adults: The role of endoscopic classification in predicting outcome

    Directory of Open Access Journals (Sweden)

    Tang Jui-Hsiang

    2008-07-01

    Full Text Available Abstract Background The ingestion of caustic substances induces an extensive spectrum of injuries to the aerodigestive tract which include extensive necrosis and perforation of the esophagus and stomach. The gold standard of safely assessing depth, extent of injury, and appropriate therapeutic regimen is esophagogastroduodenoscopy (EGD. The objective of this study was to report our clinical experience and to evaluate the role of a 6-point EGD classification system of injury in predicting outcomes in adult patients diagnosed with caustic agent ingestion. Methods The study was a retrospective medical chart review from 273 patients admitted to the Chang Gung Memorial Hospital in Tao-Yuan, Taiwan between June 1999 and July 2006 for treatment of caustic ingestion. The patients underwent EGD within 24 hours of admission and mucosal damage was graded using Zagar's modified endoscopic classification scheme. After treatment, patients were followed in the outpatient clinic for a minimum of 6 months. Results A total of 273 patients were included for analysis. Grade 3b injury was the most common caustic injury (n = 82, 30.03%, followed by grade 2b injuries (n = 62, 22.71%. Stricture was the most common complication (n = 66, 24.18%, followed by aspiration pneumonia (n = 31, 11.36%, and respiratory failure (n = 21, 7.69%. Compared to grade 3a mucosal injury, grade 3b mucosal injuries were at greater risk of prolonged hospital stay (odds ratio [OR]: 2.44; 95% confidence interval [CI]: 1.25–4.80, ICU admission (OR: 10.82; 95% CI: 2.05–200.39, and gastrointestinal (OR: 4.15; 95% CI: 1.55–13.29 and systemic complications (OR: 4.07; 95% CI: 1.81–14.07. Conclusion In patients with caustic ingestion, EGD should be performed within 12 to 24 hours and categorized according to a 6-point scale. Patients with grade 3b burns identified on endoscopy have high rates of morbidity. The 6-point scale is useful for predicting immediate and long-term complications, and

  9. 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).

  10. 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.

  11. 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.

  12. 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...

  13. 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.

  14. 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...

  15. 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)

  16. 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.

  17. 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....

  18. Critical Curves and Caustics of Triple-lens Models

    CERN Document Server

    Danek, Kamil

    2015-01-01

    Among the 25 planetary systems detected up to now by gravitational microlensing, there are two cases of a star with two planets, and two cases of a binary star with a planet. Other, yet undetected types of triple lenses include triple stars or stars with a planet with a moon. The analysis and interpretation of such events is hindered by the lack of understanding of essential characteristics of triple lenses, such as their critical curves and caustics. We present here analytical and numerical methods for mapping the critical-curve topology and caustic cusp number in the parameter space of $n$-point-mass lenses. We apply the methods to the analysis of four symmetric triple-lens models, and obtain altogether 9 different critical-curve topologies and 32 caustic structures. While these results include various generic types, they represent just a subset of all possible triple-lens critical curves and caustics. Using the analyzed models, we demonstrate interesting features of triple lenses that do not occur in two-p...

  19. Ingestion of Caustic Substances in Adults: A Review Article

    Directory of Open Access Journals (Sweden)

    Andon Chibishev

    2013-02-01

    Full Text Available Background: Ingestion of caustic agents can cause serious damages of the upper gastrointestinal tract and in some cases this kind of poisoning may have fatal outcomes. Acute caustic intoxications are one of the main problems in the modern clinical toxicology since they mainly affect young people with psychic disorders, suicidal intent, and alcohol addiction. Text: In diagnostic evaluation of this kind of poisoning, different procedures are used. Today’s golden standard for determination of the grade and extent of the lesion is esophagogastroduodenoscopy (EGD performed in the first 12-24 hours following corrosive ingestion. In some patients, some late complications, such as esophageal stenosis and gastric stenosis, which are the most common, as well as carcinoma of the upper gastrointestinal tract, which is rarely seen, can be detected. Acute caustic poisonings are treated with specific kinds of protocols. According to them, first, an attempt is made to neutralize the poison. Combinations of antibiotics, anti-secretory drugs, and collagen synthesis inhibitors are used. As a support therapy, nutritional liquids can be utilized, and in the most unmanageable cases, esophageal dilatation, stent placement and surgery are used. Conclusion: In the future, caustic poisonings will remain a serious socio-medical issue, due to the difficult clinical presentation, expensive diagnostic protocol, extended hospitalization, and possible permanent disability.

  20. 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.

  1. 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.

  2. 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.

  3. 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

  4. 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.

  5. Recovery of nickel from low grade laterite by electrochemical leaching

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Sung-Gyu; Lee, Hwa-Young; Oh, Jong-Kee [Korea Institute of Science and Technology, Seoul (Korea)

    1999-06-30

    A study on the recovery of nickel from low-grade laterite is carried out by the electrochemical leaching. The results show that the leaching reaction of Ni and Fe increases with time until 60 minutes, after which the leaching rate decreases. The leaching efficiencies of Ni and Fe are 73% and 64% at 2 hr. reaction, respectively. And current density plays an important role in the leaching rate of nickel, but power consumption increases with increase of current density which proportionally corresponds to nickel leaching. Also, the leaching efficiency of nickel appears to decrease in a small amount with increasing solid density. However, so as to reduce power consumption solid density has to be raised so long as the stirring intensity is not restricted due to heavy load. When the pH of the leaching solution is increased to 6.0, iron and nickel are remaining about 10% and 90% of initial concentrations in the leaching solution, respectively. (author). 11 refs., 2 tabs., 10 figs.

  6. 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.

  7. 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.

  8. Influence of chalcopyrite structure on their leaching by sodium nitrate in sulphuric acid

    Directory of Open Access Journals (Sweden)

    Miroslav Sokić

    2014-03-01

    Full Text Available During the chalcopyrite leaching by sodium nitrate and sulfuric acid solution, leaching rate decreases with increasing the time and a part of chalcopyrite mineral grains remains in the leach residue. In chalcopyrite concentrate, 95.5 % of chalcopyrite mineral occurs as in liberated grains, and the rest is in association with gangue minerals, which is very favorably from the aspect of hydrometallurgical treatment. Complex forms, like impregnations and complex intergrowths, do not exist. After experiments carried out, leaching of copper achieved 84 % at temperature 80 o C and time 240 min. In the all leach residues, 97 % chalcopyrite mineral grains occur as liberated with highly corroded surfaces. Therefore, the structural assembly of chalcopyrite grains is favorable and no reason to reduce the leaching rate in the final stage of reaction. Reason for this is elemental sulfur, which was formed during the reaction, precipitated at the particle surfaces, and slowed down the leaching rate in the final stage of leaching process.

  9. Leaching of used CANDU fuel: Results from a 19-year leach test under oxidizing conditions

    Energy Technology Data Exchange (ETDEWEB)

    Stroes-Gascoyne, S.; Johnson, L.H.; Tait, J.C.; McConnell, J.L.; Porth, R.J. [AECL, Pinawa, Manitoba (Canada). Whiteshell Labs.

    1997-12-31

    A fuel leaching experiment has been in progress since 1977 to study the dissolution behavior of used CANDU fuel in aerated aqueous solution. The experiment involves exposure of 50-mm clad segments of an outer element of a Pickering fuel bundle (burnup 610 GJ/kg U; linear and peak power ratings 53 and 58 kW/m, respectively), to deionized distilled water (DDH{sub 2}O, {approximately}2 mg/L carbonate) and tapwater ({approximately}50 mg/L carbonate). In 1992, it was observed that the fuel in at least one of the leaching solutions showed some signs of deterioration and, therefore, in 1993, parts of the fuel samples were sacrificed for a detailed analysis of the physical state of the fuel, using SEM and optical microscopy. Leaching results to date show that even after >6900 days only 5 to 7.7% of the total calculated inventory of {sup 137}Cs has leached out preferentially and that leach rates suggest a development towards congruent dissolution. Total amounts of {sup 137}Cs and {sup 90}Sr leached are slightly larger in tapwater than in DDH{sub 2}O. SEM examinations of leached fuel surface fragments indicate that the fuel surface exposed to DDH{sub 2}O is covered in a needle-like precipitate. The fuel surface exposed to tapwater shows evidence of leaching but no precipitate, likely because uranium is kept in solution by carbonate. Detailed optical and SEM microscopy examinations on fuel cross sections suggest that grain-boundary dissolution in DDH{sub 2}O is not prevalent, and in tapwater appears to be limited to the outer {approximately}0.5 mm (pellet/cladding) region of the fuel. Grain boundary attack seems to be limited to microcracks at or near the surface of the fuel. It thus appears that grain-boundary attack occurs only near the fuel pellet surface and is prevalent only in the presence of carbonate in solution.

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. Spectral caustics in laser assisted Breit–Wheeler process

    OpenAIRE

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

    2016-01-01

    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 ...

  15. Caustics in Tachyon Matter and Other Born-Infeld Scalars

    CERN Document Server

    Felder, G; Starobinsky, A A; Felder, Gary; Kofman, Lev; Starobinsky, Alexei

    2002-01-01

    We consider scalar Born-Infeld type theories with arbitrary potentials V(T) of a scalar field T. We find that for models with runaway potentials V(T) the generic inhomogeneous solutions after a short transient stage can be very well approximated by the solutions of a Hamilton-Jacobi equation that describes free streaming wave front propagation. The analytic solution for this wave propagation shows the formation of caustics with multi-valued regions beyond them. We verified that these caustics appear in numerical solutions of the original scalar BI non-linear equations. Our results include the scalar BI model with an exponential potential, which was recently proposed as an effective action for the string theory tachyon in the approximation where high-order spacetime derivatives of T are truncated. Since the actual string tachyon dynamics contain derivatives of all orders, the tachyon BI model with an exponential potential becomes inadequate when the caustics develop because high order spatial derivatives of T ...

  16. 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.

  17. Caustics and Rogue Waves in an Optical Sea.

    Science.gov (United States)

    Mathis, Amaury; Froehly, Luc; Toenger, Shanti; Dias, Frédéric; Genty, Goëry; Dudley, John M

    2015-08-06

    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 with broader spatial spectra. In addition, the electric field statistics of the intermediate pattern shows properties of an "optical sea" with near-Gaussian statistics in elevation amplitude, and trough-to-crest statistics that are near-Rayleigh distributed but with an extended tail where a number of rogue wave events are observed.

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

    Energy Technology Data Exchange (ETDEWEB)

    Coles, D.G.

    1981-08-20

    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 /sup 237/Np and /sup 239/Pu 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.

  19. 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

  20. 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.

  1. Effects of an expanding caustic ring on a distribution of stars

    Science.gov (United States)

    Chakrabarty, Sankha Subhra; Sikivie, Pierre

    2017-01-01

    In self-similar axially symmetric model of galactic halo, caustic rings lie on the galactic disk and expand on cosmological time scale. We study the motion of a distribution of stars under the gravitational field of an expanding caustic ring. We investigate how the bulk velocities of the stars are affected by the caustic. This work was supported in part by the Heising-Simons Foundation.

  2. 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.

  3. 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.

  4. ALUMINUM AND CHROMIUM LEACHING WORKSHOP WHITEPAPER

    Energy Technology Data Exchange (ETDEWEB)

    McCabe, D; Jeff Pike, J; Bill Wilmarth, B

    2007-04-25

    A workshop was held on January 23-24, 2007 to discuss the status of processes to leach constituents from High Level Waste (HLW) sludges at the Hanford and Savannah River Sites. The objective of the workshop was to examine the needs and requirements for the HLW flowsheet for each site, discuss the status of knowledge of the leaching processes, communicate the research plans, and identify opportunities for synergy to address knowledge gaps. The purpose of leaching of non-radioactive constituents from the sludge waste is to reduce the burden of material that must be vitrified in the HLW melter systems, resulting in reduced HLW glass waste volume, reduced disposal costs, shorter process schedules, and higher facility throughput rates. The leaching process is estimated to reduce the operating life cycle of SRS by seven years and decrease the number of HLW canisters to be disposed in the Repository by 1000 [Gillam et al., 2006]. Comparably at Hanford, the aluminum and chromium leaching processes are estimated to reduce the operating life cycle of the Waste Treatment Plant by 20 years and decrease the number of canisters to the Repository by 15,000-30,000 [Gilbert, 2007]. These leaching processes will save the Department of Energy (DOE) billions of dollars in clean up and disposal costs. The primary constituents targeted for removal by leaching are aluminum and chromium. It is desirable to have some aluminum in glass to improve its durability; however, too much aluminum can increase the sludge viscosity, glass viscosity, and reduce overall process throughput. Chromium leaching is necessary to prevent formation of crystalline compounds in the glass, but is only needed at Hanford because of differences in the sludge waste chemistry at the two sites. Improving glass formulations to increase tolerance of aluminum and chromium is another approach to decrease HLW glass volume. It is likely that an optimum condition can be found by both performing leaching and improving

  5. 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.

  6. 防污涂料中氧化亚铜的渗出速率及降解行为研究%Research on Leaching Rate & Degradation Behavior of Cu2O Contained in Antifouling Paints

    Institute of Scientific and Technical Information of China (English)

    于雪艳; 王科; 陈正涛; 余浩杰; 肖玲; 桂泰江

    2012-01-01

    Cuprous oxide is the main biocide used in marine antifouling paints, it's very important to investigate the leaching rate and degradation behavior of cuprous oxide. The ISO 15181 test method of copper-ion release rate was described in this paper, and the copper - ion release rate in different self - polishing antifouling paints formulations was discussed, and the degradation behavior of cuprous oxide in the marine environment was investigated. The results showed that the release rate of copper - ion could be adjusted by paint formula, the final degradation product of cuprous oxide in the marine environment was basic cupric carbonate.%氧化亚铜( Cu2O)作为在目前海洋防污涂料广泛使用的防污剂,研究其渗出速率和在海洋环境中的降解行为具有重要的意义.介绍了ISO15181铜离子渗出速率测试方法,并研究了不同配方的自抛光型防污涂料的铜离子渗出速率,最后研究了氧化亚铜在海洋环境中的降解行为.结果表明:铜离子渗出速率可通过涂料配方进行调整,氧化亚铜在海洋环境中的最终降解产物是碱式碳酸铜.

  7. Superboom Caustic Analysis and Measurement Program (SCAMP) Final Report

    Science.gov (United States)

    Page, Juliet; Plotkin, Ken; Hobbs, Chris; Sparrow, Vic; Salamone, Joe; Cowart, Robbie; Elmer, Kevin; Welge, H. Robert; Ladd, John; Maglieri, Domenic; Piacsek, Andrew

    2015-01-01

    The objectives of the Superboom Caustic Analysis and Measurement (SCAMP) Program were to develop and validate, via flight-test measurements, analytical models for sonic boom signatures in and around focal zones as they are expected to occur during commercial aircraft transition from subsonic to supersonic flight, and to apply these models to focus boom prediction of low-boom aircraft designs. The SCAMP program has successfully investigated sonic boom focusing both analytically and experimentally, while gathering a comprehensive empirical flight test and acoustic dataset, and developing a suite of focused sonic boom prediction tools. An experimental flight and acoustic measurement test was designed during the initial year of the SCAMP program, with execution of the SCAMP flight test occurring in May 2011. The current SCAMP team, led by Wyle, includes partners from the Boeing Company, Pennsylvania State University, Gulfstream Aerospace, Eagle Aeronautics, and Central Washington University. Numerous collaborators have also participated by supporting the experiment with human and equipment resources at their own expense. The experiment involved precision flight of a McDonnell Douglas (now Boeing) F-18B executing different maneuvers that created focused sonic booms. The maneuvers were designed to center on the flight regime expected for commercial supersonic aircraft transonic transition, and also span a range of caustic curvatures in order to provide a variety of conditions for code validations. The SCAMP experiment was designed to capture concurrent F-18B on-board flight instrumentation data, high-fidelity ground-based and airborne acoustic data, and surface and upper air meteorological data. Close coordination with NASA Dryden resulted in the development of new experimental instrumentation and techniques to facilitate the SCAMP flight-test execution, including the development of an F-18B Mach rate cockpit display, TG-14 powered glider in-flight sonic boom measurement

  8. 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}.

  9. Leaching behavior of microtektite glass compositions in sea water and the effect of precipitation on glass leaching

    Science.gov (United States)

    1991-01-01

    The present study attempts to account for the slow corrosion rates of microtektite glass in nature by comparing the leach rates of synthetic microtektite glass samples in deionized water and in sea-water, respectively. In order to obtain systematic data about leachant composition effects, leach tests were also carried out with synthetic leachant compositions enriched with respect to silica or depleted with respect to certain major components of sea-water (Mg, Ca).

  10. Leaching of toluene-neoprene adhesive wastes.

    Science.gov (United States)

    Font, R; Sabater, M C; Martínez, M A

    2001-03-01

    This work consists of the study of the extraction of solvent (toluene) from a polymeric (neoprene) substrate during a leaching process. Total organic carbon (TOC) is the main contaminant parameter in the leaching of these systems due to the solution of the toluene and the dispersion of the polymer. The toxicity of the extracts was measured with a Microtox equipment, using Photobacteria phosphoreum, deducing that the toxicity of the extracts is low due to the low solubility of toluene but that the toxicity of toluene is high. On the basis of the experimental results, the amount of toluene diffused vs time in plane sheet systems was studied. A kinetic model has been developed considering two stages: In the first stage, the toluene diffuses into the system across the neoprene chains at a constant rate, not depending on the initial toluene concentration. This fact is explained by considering that there is a constant difference of the toluene concentration between the interface with the water and the inner part of the sample. In the second stage, the dispersion of the polymer with the corresponding amount of toluene takes place. The diffusion of toluene in the leaching process is compared and analyzed considering the diffusion of toluene in a desorption process in air so that the difference of toluene concentration between the interface and the interior can be estimated. A mathematical model is also proposed for considering the leaching process in other operating conditions.

  11. 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...

  12. 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.

  13. 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.

  14. 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.

  15. Using microbiological leaching method to remove heavy metals from sludge

    Directory of Open Access Journals (Sweden)

    Zhuyu Gu

    2017-01-01

    Full Text Available Microbial leaching is one of the most effective methods to remove heavy metals from sludge. In the conducted researches, the sludge samples were processed with Thiobacillus ferrooxidans and Thiobacillus thiooxidans obtained via cultivation, extraction and purification processes. Heavy metals such as Pb, Cd, Cu and Ni were leached from sludge by Thiobacillus ferrooxidans and Thiobacillus thiooxidans within different substrate concentration and pH value conditions. It is defined that from the point of view of economy and efficiency the optimal concentration of FeSO4.7H2O and sulfur for bio-leaching process was 0.2 g. The leaching rates of heavy metals such as Pb, Cd, Cu and Ni of the same concentration were 74.72%, 81.54%, 70.46% and 77.35% respectively. However, no significant differences depending on the pH value among the leaching rates were defined, even for the pH value of 1.5. Along with the removal of heavy metals from sludge, the organic matter, N, P, K were also leached to some extent. The losing rate of phosphorus was the highest and reached 38.44%. However, the content of organic matter, N, P, K in the processed sludge were higher in comparison with level I of the National Soil Quality Standards of China. Ecological risk of heavy metals in sludge before and after leaching was assessed by Index of Geo-accumulation (Igeo and comprehensive potential risk (RI. The results of research defined that the content of heavy metals in sludge meets the level of low ecological risk after leaching and their contents is lower in comparison with the National Agricultural Sludge Standard of China. Sludge leached by biological methods is possible to use for treatment for increasing soil fertility.

  16. 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.

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

    Energy Technology Data Exchange (ETDEWEB)

    Coles, D.G.

    1981-01-22

    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 /sup 237/Np and /sup 239/Pu 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 temperature, at all three flow rates, and with all three leachant compositions varied 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 also indicated that matrix dissolution may be the dominant leaching mechanism, at least for Np in bicarbonate leachant. Regardless of the leaching mechanism the importance of this study is that it bounds the effects of repository environments when the ground water is oxidizing and when it doesn't reach the waste form until the waste has cooled to ambient rock temperature.

  18. 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.

  19. Caustic-based approach to understanding bunching dynamics and current spike formation in particle bunches

    Science.gov (United States)

    Charles, T. K.; Paganin, D. M.; Dowd, R. T.

    2016-10-01

    Current modulations, current spikes, and current horns, are observed in a range of accelerator physics applications including strong bunch compression in Free Electron Lasers and linear colliders, trains of microbunching for terahertz radiation, microbunching instability and many others. This paper considers the fundamental mechanism that drives intense current modulations in dispersive regions, beyond the common explanation of nonlinear and higher-order effects. Under certain conditions, neighboring electron trajectories merge to form caustics, and often result in characteristic current spikes. Caustic lines and surfaces are regions of maximum electron density, and are witnessed in accelerator physics as folds in phase space of accelerated bunches. We identify the caustic phenomenon resulting in cusplike current profiles and derive an expression which describes the conditions needed for particle-bunch caustic formation in dispersive regions. The caustic expression not only reveals the conditions necessary for caustics to form but also where in longitudinal space the caustics will form. Particle-tracking simulations are used to verify these findings. We discuss the broader implications of this work including how to utilize the caustic expression for manipulation of the longitudinal phase space to achieve a desired current profile shape.

  20. 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)...

  1. 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

  2. Leaching From Biomass Gasification Residues

    DEFF Research Database (Denmark)

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

    2011-01-01

    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 with geoche...

  3. 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.

  4. Preferential Leaching of Pinitol from Soybeans during Imbibition.

    Science.gov (United States)

    Nordin, P

    1984-10-01

    Sugars and cyclitols leached from soybeans (Glycine max var Sparks) during imbibition were assayed as a function of time. Pinitol leached many times faster than carbohydrates. During the initial 20 minutes of imibition, the pinitol/carbohydrate ratio was 3.4, declining to 0.29 for fully imbibed seeds. The value for dry soybeans was 0.14. Hypochlorite treatment of seeds more than doubled the rate at which carbohydrates leached out, but had little effect on pinitol. A role in development of soil microorganisms is postulated for pinitol.

  5. 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.

  6. A mathematical model for isothermal heap and column leaching

    Directory of Open Access Journals (Sweden)

    Lima L.R.P. de Andrade

    2004-01-01

    Full Text Available Leaching occurs in metals recovery, in contaminated soil washing, and in many natural processes, such as fertilizer dissolution and rock weathering. This paper presents a model developed to simulate the transient evolution of the dissolved chemical species in the heap and column isothermal leaching processes. In this model, the solid bed is numerically divided into plane layers; the recovery of the chemical species, the enrichment of the pregnant leach solution, and the residual concentration of the leaching agent are calculated by interactions among the layers. The solution flow in the solid bed is assumed as unidirectional without dispersion, and the solid-fluid reaction is described by a diffusive control model that is integrated analytically for each time step. The data set used in the model include physical-chemical, geometrical, and operational variables, such as: leachable chemical species content, leaching agent flow rate and concentration, particles size distribution, solution residence time in the solid bed, and solid bed length, weight and irrigated area. The results for two case studies, namely, an industrial gold heap leaching and a pilot column copper acid leaching, showed that the model successful predict the general features of the process time evolution.

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. 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

  12. 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.

  13. 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.

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

    Institute of Scientific and Technical Information of China (English)

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

    2016-01-01

    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 leach-ing efficiency of manganese and superior selectivity against calcium compared to hydrochloric acid. The optimal leaching conditions in sul-furic acid media were determined; under the optimal conditions, the leaching efficiencies of Mn and Ca were 92.42% and 9.61%, respec-tively. Moreover, the kinetics of manganese leaching indicated that the leaching follows the diffusion-controlled model with an apparent ac-tivation 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.

  15. 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.

  16. Reduced nitrogen leaching by intercropping maize with red fescue on sandy soils in North Europe

    DEFF Research Database (Denmark)

    Manevski, Kiril; Børgesen, Christen Duus; Andersen, Mathias Neumann

    2015-01-01

    effects on the maize systems. Results Intercropped maize had 15–37 % lower N leaching than monocrop maize. Maize intercropping following a maize crop was achieved without yield loss at the standard N rate or higher, while red fescue offset N leaching. Maize intercropping following grass-clover needed less...... N, thereby greatly reducing the N leaching. Conclusions The hypothesis that maize intercropping with fertilizer N rates applicable to monocrop maize decreases N leaching without significant yield loss was largely supported given the effect of cropping history and soil type. The applicability...

  17. Kinetics of the Carbonate Leaching for Calcium Metavanadate

    Directory of Open Access Journals (Sweden)

    Peiyang Shi

    2016-10-01

    Full Text Available The sodium salt roasting process was widely used for extracting vanadium due to its high yield rate of vanadium. However, the serious pollution was a problem. The calcium roasting process was environmentally friendly, but the yield rate of vanadium was relatively lower. Focusing on the calcium metavanadate produced in the calcium roasting process of vanadium minerals, the mechanism of the carbonate leaching for calcium metavanadate and its leaching kinetics of calcium metavanadate were studied. With the increase of the leaching agent content, the decrease of the particle size, the increase of the temperature and the increase of the reaction time, the leaching rate of vanadium increased, and the constant of reaction rate increased. In the carbonate leaching process, the calcium carbonate was globular and attached to the surface of calcium metavanadate. In the solution containing bicarbonate radical, lots of cracks formed in the dissolution process. However, the cracks were relatively fewer in the solution containing carbonate. In the present study, the carbonate leaching for calcium metavanadate was controlled by diffusion, the activation energy reached maximum and minimum in the sodium bicarbonate and the sodium carbonate solution, respectively. The activation energy value in the ammonium bicarbonate solution was between those two solutions. The kinetic equations of the carbonate leaching for calcium metavanadate were as follows: 1 − 2/3η − (1 − η2/3 = 4.39[Na2CO3]0.75/r0 × exp(−2527.06/Tt; 1 − 2/3η − (1 − η2/3 = 7.89[NaHCO3]0.53/r0 × exp(−2530.67/Tt; 1 − 2/3η − (1 − η2/3 = 6.78[NH4HCO3]0.69/r0 × exp(−2459.71/Tt.

  18. 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.

  19. Experimental Study of Preferential Solute Transportation During Dump Leaching

    Institute of Scientific and Technical Information of China (English)

    YIN Sheng-hua; WU Ai-xiang

    2006-01-01

    The production of dump leaching of the Dexing Copper Mine was affected by a preferential solution flow. Formative mechanism of the preferential solution flow was investigated by analyzing the relationship between both dump permeability and surface tension and ore diameter. The preferential solution flow occurred in the fine ore area when the application rate was low. The preferential solution flow entered into the coarse ore area because the negative pore water pressure disappeared with an increase of the application rate. The preferential solute transportation experiment was conducted by selecting NaCl as mineral. Results of the experiment showed that the concentration of the outflow solution reduced over time. The concentration of the coarse ore area outflow solution was greater than that of the fine ore area. The process of NaCl leaching can be divided into two stages. NaCl was carried out directly by diffusion-convection during the first stage, so the leaching rate increased sharply. But in the second stage, only a small amount of NaCl dissolved in the immobile water. The leaching rate increased slowly because NaCl, dissolved in the immobile water, can only be leached by diffusion.

  20. 提高含砷金精矿二段焙烧-氰化工艺金浸出率的试验研究%Experimental researches on enhancing gold leaching rate of a gold concentrate containing arsenic with two-stage roasting and cyanidation technique

    Institute of Scientific and Technical Information of China (English)

    薛光; 王永新; 薛元昕

    2011-01-01

    Based on experimental researches, a two-stage roasting and cyanidation technique is proposed to enhance the gold leaching rate of a gold concentrate containing arsenic. After the first stage roasting (450 ~ 500 ℃ ) to remove arsenic, an additive SR is added before the second stage roasting(630 ~ 650 ℃ ), and thendilute sulphuric acid is used for copper removal, the final process is cyanidation leaching. The test results show that the leaching rate of gold increases 4.65 %, and good economic and social benefits are obtained.%在试验研究基础上,提出了一种提高含砷金精矿二段焙烧-氰化浸出工艺金浸出率方法.试验结果表明,含砷金精矿经一段焙烧(450~500℃)除砷后,加入一定量的添加剂SR,再进行二段焙烧(630~650℃),然后经稀硫酸除铜后进行氰化浸出,可使金的氰化浸出率提高4.65%.该方法可获得较好的经济效益和社会效益.

  1. 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.

  2. 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.

  3. 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.

  4. Caustics, pseudocaustics and the related illuminated and dark regions with the computational method of quantifier elimination

    Science.gov (United States)

    Ioakimidis, Nikolaos I.

    2017-01-01

    The method of caustics is a powerful experimental method in elasticity and particularly in fracture mechanics for crack problems. The related method of pseudocaustics is also of interest. Here we apply the computational method of quantifier elimination implemented in the computer algebra system Mathematica in order to determine (i) the non-parametric equation and two properties of the caustic at a crack tip and especially (ii) the illuminated and the dark regions related to caustics and pseudocaustics in plane elasticity and plate problems. The present computations concern: (i) The derivation of the non-parametric equation of the classical caustic about a crack tip through the elimination of the parameter involved (here the polar angle) as well as two geometrical properties of this caustic. (ii) The derivation of the inequalities defining the illuminated region on the screen in the problem of an elastic half-plane loaded normally by a concentrated load with the boundary of this illuminated region related to some extent to the caustic formed. (iii) Similarly for the problem of a clamped circular plate under a uniform loading with respect to the caustic and the pseudocaustic formed. (iv) Analogously for the problem of an equilateral triangular plate loaded by uniformly distributed moments along its whole boundary, which defines the related pseudocaustic. (v) The determination of quantities of interest in mechanics from the obtained caustics or pseudocaustics. The kind of computations in the applications (ii) to (iv), i.e. the derivation of inequalities defining the illuminated region on the screen, seems to be completely new independently of the use here of the method of quantifier elimination. Additional applications are also possible, but some of them require the expansion of the present somewhat limited power of the quantifier elimination algorithms in Mathematica. This is expected to take place in the future.

  5. 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.

  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. 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.

  8. Leaching kinetics of gibbsitic bauxite with sodium hydroxide

    Directory of Open Access Journals (Sweden)

    Abdel-Aal El-Sayed A.

    2016-01-01

    Full Text Available In this paper the results of a leaching kinetics study of bauxite ore with sodium hydroxide are presented. The effect of ore particle size, sodium hydroxide concentration and reaction temperature on the Al2O3 extraction rate was determined. The results obtained showed that 99% of Al2O3 was leached out using −200+270 mesh ore particle size at a reaction temperature of 105 °C for 60 min reaction time with 250 g/L NaOH. The solid-to-liquid ratio was maintained constant at 1:20. The results indicated that leaching of bauxite is the rate controlling process. The activation energy was determined to be 46.04 kJ/mole, which was characteristic for a chemically controlled process.

  9. 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.

  10. Comparative study on copper leaching from waste printed circuit boards by typical ionic liquid acids.

    Science.gov (United States)

    Chen, Mengjun; Huang, Jinxiu; Ogunseitan, Oladele A; Zhu, Nengming; Wang, Yan-min

    2015-07-01

    Waste printed circuit boards (WPCBs) are attracting increasing concerns because the recovery of its content of valuable metallic resources is hampered by the presence of hazardous substances. In this study, we used ionic liquids (IL) to leach copper from WPCBs. [BSO3HPy]OTf, [BSO3HMIm]OTf, [BSO4HPy]HSO4, [BSO4HMim]HSO4 and [MIm]HSO4 were selected. Factors that affect copper leaching rate were investigated in detail and their leaching kinetics were also examined with the comparison of [Bmim]HSO4. The results showed that all six IL acids could successfully leach copper out, with near 100% recovery. WPCB particle size and leaching time had similar influences on copper leaching performance, while IL acid concentration, hydrogen peroxide addition, solid to liquid ratio, temperature, showed different influences. Moreover, IL acid with HSO4(-) was more efficient than IL acid with CF3SO3(-). These six IL acids indicate a similar behavior with common inorganic acids, except temperature since copper leaching rate of some IL acids decreases with its increase. The results of leaching kinetics studies showed that diffusion plays a more important role than surface reaction, whereas copper leaching by inorganic acids is usually controlled by surface reaction. This innovation provides a new option for recovering valuable materials such as copper from WPCBs.

  11. 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...

  12. Wavefields Near Transverse Cusp Caustics Produced by Reflecting Ultrasonic Transients and Tone Bursts from Curved Surfaces.

    Science.gov (United States)

    Frederickson, Carl King

    Ultrasonic wavefields reflected from curved surfaces were studied in the vicinity of caustics. Acoustical and optical transverse cusp diffraction catastrophes produced by reflections from a curved metal surface in water were imaged by displaying the amplitude or intensity in an observation plane transverse to the general direction of propagation. The optical image was used to locate the cusp point in the observation plane. Acoustical diffraction patterns for sine waves, described by the Pearcey function, were calculated with the parameters determined by the experimental setup leaving no adjustable scaling parameters. The calculated and experimental acoustical diffraction patterns showed good agreement near the cusp point. The acoustical diffraction pattern showed the expected mirror symmetry about an axis. The pattern was shown to scale properly with frequency. The transverse cusp caustic separates space into a region with three rays and a region with one ray. Inside the caustic there are three rays, on the curve two of the rays merge and disappear leaving one ray outside. Transient signals reflected from curved surfaces exhibited the merging and disappearance of rays on the caustic. Relative arrival times for signals in calculated and recorded time traces agree well. The relation to the wavefront parameters of the temporal orientation of the travel time surface is discussed. The general shape of the travel time surface is that of the swallow tail caustic surface. The temporal shape of the transient echoes was seen to be generally that of the incident signal or of its Hilbert transform. The Hilbert transform shape identifies the signals that have touched the caustic. The observed arrival sequence of the transient signals was shh inside the caustic and one h outside, where s stands for a signal with the general shape of the incident signal and h for its Hilbert transform. The relation between the surface and wavefront parameters and the arrival sequence is given.

  13. 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.

  14. Leaching study of PNL 76-68 glass beads using the LLNL continuous-flow method and the PNL-modified IAEA method. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Buddemeier, R.W.; Coles, D.G.; Mensing, R.W.; Rego, J.; Weed, H.C.

    1982-08-20

    Lawrence Livermore National Laboratory (LLNL) has conducted a long-term single-pass continuous-flow (SPCF) leaching test of the glass waste form PNL 76-68. Leaching rates of Np, Pu, and various stable elements were measured at 25/sup 0/ and 75/sup 0/C with three different solutions and three different flow rates. The purposes of the study were: (1) to compare SPCF leaching results with the results of a modified IAEA leach test performed by Pacific Northwest Laboratories (PNL); (2) to establish elemental leach rates and their variation with temperature, flow rate and solution composition; and (3) to gain insight into the leaching mechanisms. The LLNL and PNL leach tests yielded results which appear to agree within experimental uncertainties. The magnitude of the leach rates determined for Np and the glass matrix elements is 10/sup -5/ grams of glass/cm/sup 2/ geometric solid surface area/day. The rates increase with temperature and with solution flow rate, and are similar in brine and distilled water but higher in a bicarbonate solution. Other cations exhibit somewhat different behavior, and Pu in particular yields a much lower apparent leach rate, probably because of sorption or precipitation effects after release from the glass matrix. After the initial few days, most elements are leached at a constant rate. Matrix dissolution appears to be the most probable rate controlling step for the leaching of most elements.

  15. Free-fall accretion and emitting caustics in wind-fed X-ray sources

    CERN Document Server

    Illarionov, A F; Illarionov, Andrei F.; Beloborodov, Andrei M.

    2000-01-01

    In wind-fed X-ray binaries, the accreting matter is Compton cooled and falls freely onto the compact object. The matter has a modest angular momentum, $l$, and accretion is quasi-spherical at large distances from the compact object. Initially small non-radial velocities grow in the converging supersonic flow and become substantial in the vicinity of the accretor. The streamlines with $l>(GMR_*)^{1/2}$ (where $M$ and $R_*$ are the mass and radius of the compact object) intersect outside $R_*$ and form a two-dimensional caustic which emits X-rays. The streamlines with low angular momentum, $l<(GMR_*)^{1/2}$, run into the accretor. If the accretor is a neutron star, a large X-ray luminosity results. We show that the distribution of accretion rate/luminosity over the star surface is sensitive to the angular momentum distribution of the accreting matter. The apparent luminosity depends on the side from which the star is observed and can change periodically with the orbital phase of the binary. The accretor then...

  16. 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.

  17. Faraday caustics: Singularities in the Faraday spectrum and their utility as probes of magnetic field properties

    CERN Document Server

    Bell, M R; Enßlin, T A

    2011-01-01

    We describe singularities in the distribution of polarized intensity as a function of Faraday depth (i.e. the Faraday spectrum) that arise due to line of sight (LOS) magnetic field reversals. We call these features Faraday caustics due to their similarity to optical caustics. They appear sharply spiked in the Faraday spectrum with a tail that extends to one side. The direction in which the tail extends depends on the way in which the LOS magnetic field reversal occurs (either changing from oncoming to retreating or vice versa). We describe how surfaces of Faraday caustics relate to boundaries between regions where the LOS magnetic field has opposite polarity. Examples from simulations of the polarized synchrotron emission from the Milky Way are provided. We derive the probability or luminosity distribution of Faraday caustics produced in a Gaussian magnetic field distribution as a function of their strength, F, and find that for strong Faraday caustics P(F) ~ F^(-3). If fully resolved, this distribution is al...

  18. 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.

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

    Science.gov (United States)

    Zhu, Xiaobo; Li, Wang; Guan, Xuemao

    2015-04-09

    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.

  20. 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.

  1. 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.

  2. 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.

  3. Leaching study of PNL 76-68 glass beads using the LLNL continuous-flow method and the PNL modified IAEA method. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Coles, D.G.; Mensing, R.W.; Rego, J.; Weed, H.C.; Buddemeier, R.W.

    1982-10-04

    A long-term single-pass continuous-flow (SPCF) leaching test was conducted on the glass waste form PNL 76-68. Leaching rates of Np, Pu and various stable elements were measured at 25 and 75/sup 0/C with three different solutions and three different flow rates. The SPCF leaching results were compared with results of a modified IAEA leach test performed by Pacific Northwest Laboratories (PNL). Elemental leach rates and their variation with temperature, flow rate and solution composition were established. The LLNL and PNL leach test results appear to agree within experimental uncertainties. The magnitude of the leach rates determined for Np and the glass matrix elements is 10/sup -5/ grams of glass/cm/sup 2/ geometric solid surface area/day. The rates increase with temperature and with solution flow rate, and are similar in brine and distilled water but higher in a bicarbonate solution. Other cations exhibit somewhat different behavior, and Pu in particular yields a much lower apparent leach rate, probably because of sorption or precipitation effects after release from the glass matrix. After the initial few days, most elements are leached at a constant rate. Matrix dissolution appears to be the most probable rate controlling step for the leaching of most elements. 23 figures, 12 tables.

  4. [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.

  5. Observing phthalate leaching from plasticized polymer films at the molecular level.

    Science.gov (United States)

    Zhang, Xiaoxian; Chen, Zhan

    2014-05-06

    Phthalates, the most widely used plasticizers in poly(vinyl chloride) (PVC), have been extensively studied. In this paper, a highly sensitive, easy, and effective method was developed to examine short-term phthalate leaching from PVC/phthalate films at the molecular level using sum frequency generation vibrational spectroscopy (SFG). Combining SFG and Fourier transform infrared spectroscopy (FTIR), surface and bulk molecular structures of PVC/phthalate films were also comprehensively evaluated during the phthalate leaching process under various environments. The leaching processes of two phthalates, diethyl phthalate (DEP) and dibutyl phthalate (DBP), from the PVC/phthalate films with various weight ratios were studied. Oxygen plasma was applied to treat the PVC/phthalate film surfaces to verify its efficacy on preventing/reducing phthalate leaching from PVC. Our results show that DBP is more stable than DEP in PVC/phthalate films. Even so, DBP molecules were still found to very slowly leach to the environment from PVC at 30 °C, at a rate much slower than DEP. Also, the bulk DBP content substantially influences the DBP leaching. Higher DBP bulk concentration yields less stable DBP molecules in the PVC matrix, allowing molecules to leach from the polymer film more easily. Additionally, DBP leaching is very sensitive to temperature changes; higher temperature can strongly enhance the leaching process. For most cases, the oxygen plasma treatment can effectively prevent phthalate leaching from PVC films (e.g., for samples with low bulk concentrations of DBP-5 and 30 wt %). It is also capable of reducing phthalate leaching from high DBP bulk concentration PVC samples (e.g., 70 wt % DBP in PVC/DBP mixture). This research develops a highly sensitive method to detect chemicals at the molecular level as well as provides surface and bulk molecular structural changes. The method developed here is general and can be applied to detect small amounts of chemical

  6. 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.

  7. 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

  8. 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.

  9. 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...

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

    Science.gov (United States)

    Fang, Wen; Wei, Yonghong; Liu, Jianguo

    2016-06-05

    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 (6heavy metal speciation in the solid phase were similar between the reference soil and the amended soil.

  11. 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.

  12. Passivation of chalcopyrite during the leaching with sulphuric acid solution in presence of sodium nitrate

    Directory of Open Access Journals (Sweden)

    Sokić Miroslav D.

    2010-01-01

    Full Text Available In this work, the process of the chalcopyrite leaching in sulphuric acid solution was investigated. Sodium nitrate was used as oxidant in the leaching process. Chemical reactions of leaching and their thermodynamic possibilities are predicted based on the calculated Gibbs energies and analysis of E−pH diagrams. The negative values of the Gibbs energy show that all chemical reactions are thermodynamically feasible at atmospheric pressure and in a temperature range 25-90°C. At high electrode potential and low pH values, Cu2+, Fe2+ and Fe3+ ions exist in water solutions. The increase of temperature reduces the probability of Fe3+ ion existence in the system. The chalcopyrite concentrate, enriched in the “Rudnik” flotation plant, with 27.08% Cu, 25.12% Fe, 4.15% Zn and 2.28% Pb was used in the work. XRD and DTA analysis of the concentrate reveals that the sample contains mainly the chalcopyrite with small amount of sphalerite. For the description of the reaction of leaching process the leach residuals, obtained at different conditions, were chosen for XRD, TG/DTA and SEM/EDX analyses. The elemental sulphur and chalcopyrite phases identified in leach residuals confirm our prediction that the elemental sulphur is formed during the leaching process. Accordingly, elemental sulphur is the main product of the reaction, while a minor amount of sulphide sulphur is oxidized to sulphate during the leaching. The sulphur formed during the reaction was precipitated at the particle surfaces, and slowed down the leaching rate in the final stage of leaching process. In the initial stage, the reaction rate was controlled by the surface reaction. The mechanism, latter has been changed into a diffusion controlled one.

  13. 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.

  14. Phosphorus leaching in soils amended with piggery effluent or lime residues from effluent treatment.

    Science.gov (United States)

    Weaver, D M; Ritchie, G S

    1994-01-01

    Phosphorus (P) in wastes from piggeries may contribute to the eutrophication of waterways if not disposed of appropriately. Phosphorus leaching, from three soils with different P sorption characteristics (two with low P retention and one with moderate P retention) when treated with piggery effluent (with or without struvite), was investigated using batch and leaching experiments. The leaching of P retained in soil from the application of struvite effluent was determined. In addition, P leaching from lime residues (resulting from the treatment of piggery effluent with lime to remove P) was determined in comparison to superphosphate when applied to the same three soils. Most P was leached from sandy soils with low P retention when effluent with or without struvite was applied. More than 100% of the filterable P applied in struvite effluent was leached in sandy soils with low P retention. Solid, inorganic forms of P (struvite) became soluble and potentially leachable at pHdissolution if there were sufficient sorption sites. In sandy soils with low P retention, more than 39% of the total filterable P applied in recycled effluent (without struvite) was leached. Soil P increased mainly in surface layers after treatment with effluent. Sandy soils pre-treated with struvite effluent leached 40% of the P retained in the previous application. Phosphorus decreased in surface layers and increased at depth in the soil with moderate P retention after leaching the struvite effluent pre-treated soil with water. The soils capacity to adsorb P and the soil pH were the major soil properties that affected the rate and amount of P leaching, whereas the important characteristics of the effluent were pH, P concentration and the forms of P in the effluent. Phosphorus losses from soils amended with hydrated lime and lime kiln dust residues were much lower than losses from soils amended with superphosphate. Up to 92% of the P applied as superphosphate was leached from sandy soils with low P

  15. Nitrate leaching from Silage Maize

    OpenAIRE

    Hansen, Elly Møller; Eriksen, Jørgen

    2009-01-01

    During the last 20 years the area with maize in Denmark has increased dramatically and reached 163,000 ha in 2008. Silage maize is easy to grow, is a suitable fodder for cows and goes well with grass-clover in the diet. This means that silage maize is often found in crop rotations with grass-clover on sandy soils in western Denmark. The ploughing in of grass-clover fields poses a serious risk of increased nitrate leaching on a coarse sandy soil, even when carried out in spring. With increased...

  16. 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.

  17. Curvilinear wave-equation angle transform: Caustics, turning rays, absence of kinematic artifacts

    NARCIS (Netherlands)

    Stolk, C.C.; De Hoop, M.V.

    2007-01-01

    Migration of seismic reflection data to common image-point gathers is an integral part of both migration velocity analysis (MVA) and amplitude (AVA) analysis. Its applicability in complex geology depends on whether these gathers will be artifact free, and is related to the formation of caustics and

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

    Energy Technology Data Exchange (ETDEWEB)

    Leshikar, G.A.

    1995-06-16

    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.

  19. 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

  20. Prediction of complications following unintentional caustic ingestion in children. Is endoscopy always necessary?

    DEFF Research Database (Denmark)

    Christesen, H B

    1995-01-01

    The records of 115 children hospitalized following caustic ingestion over an 18.5-year period from 1976 to 1994 were reviewed. The relationship between types of product ingested, signs and symptoms, degree of esophageal injury and complications was analyzed. All complications were the result of s...

  1. 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.

  2. Caustic-Side Solvent Extraction: Chemical and Physical Properties of the Optimized Solvent

    Energy Technology Data Exchange (ETDEWEB)

    Delmau, L.H.

    2002-10-08

    This work was undertaken to optimize the solvent used in the Caustic Side Solvent Extraction (CSSX) process and to measure key chemical and physical properties related to its performance in the removal of cesium from the alkaline high-level salt waste stored in tanks at the Savannah River Site. The need to adjust the solvent composition arose from the prior discovery that the previous baseline solvent was supersaturated with respect to the calixarene extractant. The following solvent-component concentrations in Isopar{reg_sign} L diluent are recommended: 0.007 M calix[4]arene-bis(tert-octylbenzo-crown-6) (BOBCalixC6) extractant, 0.75 M 1-(2,2,3,3-tetrafluoropropoxy)-3-(4-sec-butylphenoxy)-2-propanol (Cs-7SB) phase modifier, and 0.003 M tri-n-octylamine (TOA) stripping aid. Criteria for this selection included BOBCalixC6 solubility, batch cesium distribution ratios (D{sub Cs}), calculated flowsheet robustness, third-phase formation, coalescence rate (dispersion numbers), and solvent density. Although minor compromises within acceptable limits were made in flowsheet robustness and solvent density, significant benefits were gained in lower risk of third-phase formation and lower solvent cost. Data are also reported for the optimized solvent regarding the temperature dependence of D{sub Cs} in extraction, scrubbing, and stripping (ESS); ESS performance on recycle; partitioning of BOBCalixC6, Cs-7SB, and TOA to aqueous process solutions; partitioning of organic anions; distribution of metals; solvent phase separation at low temperatures; solvent stability to elevated temperatures; and solvent density and viscosity. Overall, the technical risk of the CSSX process has been reduced by resolving previously identified issues and raising no new issues.

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

    Institute of Scientific and Technical Information of China (English)

    蔡创开; 庄荣传; 林鸿汉

    2015-01-01

    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.%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 .

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. LEACHING OF METALS FROM MINERAL PROCESSING WASTE

    Science.gov (United States)

    The purpose of this project is to test the leaching of Mineral Processing Waste (MPW) contaminated with heavy metals using scientifically defendable leaching tests other than TCLP. Past experience and literature have shown that TCLP underestimates the levels of metals such as oxo...

  9. Properties of Leach-Flessas-Gorringe polynomials

    Science.gov (United States)

    Pursey, D. L.

    1990-09-01

    A generating function is obtained for the polynomials recently introduced by Leach, Flessas, and Gorringe [J. Math. Phys. 30, 406 (1989)], and is then used to relate the Leach-Flessas-Gorringe (or LFG) polynomials to Hermite polynomials. The generating function is also used to express a number of integrals involving the LFG polynomials as finite sums of parabolic cylinder functions.

  10. 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/...

  11. 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.

  12. 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

  13. 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...

  14. 麦草氨法制浆工艺及动力学%Pulping of Wheat Straw with Caustic Potash-Ammonia Aqueous Solutions and Its Kinetics

    Institute of Scientific and Technical Information of China (English)

    黄国林; 张成芳; 陈中胜

    2006-01-01

    A pulping technology of wheat straw with aqueous ammonia and diluent caustic potash was investigated.Because its strong alkalinity, the addition of caustic potash not only reduced the quantity of NH3 consumed and cooking time, but also enriched the black liquor with nutrients such as potassium and nitrogen, which could be used as fertilizer for agriculture. Various pulping conditions including composition of cooking liquor, liquor-to-solid ratio,maximum cooking temperature, time to reach the maximum temperature and time at the maximum temperature were studied systematically to determine the suitable pulping conditions. Results of the cooking course showed that there were three distinct delignification phases, namely, the bulk delignification phase from the beginning of cooking to 100 ℃, the supplementary delignification phase from 100 ℃ to 155 ℃ for 45min and the third delignification phase till the end of cooking. The rate of delignification was found to be first order with respect to residual lignin and 0.34 order with respect to [OH-]. The activation energy of the delignification reaction was 29.75 kJ·mol-1 and the rate equation of delignification was also obtained.

  15. 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。

  16. Phosphorus leaching in a soil textural gradient

    DEFF Research Database (Denmark)

    Glæsner, Nadia; Kjærgaard, Charlotte; Rubæk, Gitte Holton;

    2009-01-01

    Texture is a major factor influencing mobilization and transport of P in soil owing partly to differences in adsorptive properties, and partly to differences in pore-size distribution and pore organization. Slurry application strategies may be important mitigation measures for reducing agricultural...... P leaching. We propose diverse interactions between dominant flow pathways and cattle slurry: - Injection of slurry reduces P leaching compared to surface application in soils with preferential flow behaviour - Injection of slurry has less impact on P leaching compared to surface application...... in soils with matrix dominated flow behaviour We tested these hypotheses on three textural soil classes (Olsen-P 1.6 mg P 100 g-1) on intact soil columns (20*20 cm) and compared them to in situ P leaching before slurry application. In a loamy sand P leaching with both slurry application techniques slightly...

  17. 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.  

  18. 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.

  19. Leaching of heavy metals from steelmaking slags

    Energy Technology Data Exchange (ETDEWEB)

    Gomez, J. F. P.; Pino, C. G.

    2006-07-01

    Leaching tests with EAF and Ladle slags were performed, using a flow through tests 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, and 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, slang samples submitted to these trials presented very low total leaching levels. The most extracted elements are calcium and magnesium. Nevertheless, in flow-though 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). (Author) 12 refs.

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

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Jinxiu; Chen, Mengjun, E-mail: kyling@swust.edu.cn; Chen, Haiyan; Chen, Shu; Sun, Quan

    2014-02-15

    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 E{sub a} was 25.36 kJ/mol. - Abstract: In this work, a Brønsted acidic ionic liquid, 1-butyl-3-methyl-imidazolium hydrogen sulfate ([bmim]HSO{sub 4}), 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]HSO{sub 4} 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.

  1. Embryotoxicity assays for leached components from dental restorative materials

    OpenAIRE

    Mummolo Stefano; Tecco Simona; Gallusi Gianni; Farini Donatella; Klinger Francesca G; Marzo Giuseppe; Libonati Antonio; De Felici Massimo; Campanella Vincenzo

    2011-01-01

    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 mo...

  2. 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.

  3. Leach test methodology for the Waste/Rock Interactions Technology Program

    Energy Technology Data Exchange (ETDEWEB)

    Bradley, D.J.; McVay, G.L.; Coles, D.G.

    1980-05-01

    Experimental leach studies in the WRIT Program have two primary functions. The first is to determine radionuclide release from waste forms in laboratory environments which attempt to simulate repository conditions. The second is to elucidate leach mechanisms which can ultimately be incorporated into nearfield transport models. The tests have been utilized to generate rates of removal of elements from various waste forms and to provide specimens for surface analysis. Correlation between constituents released to the solution and corresponding solid state profiles is invaluable in the development of a leach mechanism. Several tests methods are employed in our studies which simulate various proposed leach incident scenarios. Static tests include low temperature (below 100/sup 0/C) and high temperature (above 100/sup 0/C) hydrothermal tests. These tests reproduce nonflow or low-flow repository conditions and can be used to compare materials and leach solution effects. The dynamic tests include single-pass, continuous-flow(SPCF) and solution-change (IAA)-type tests in which the leach solutions are changed at specific time intervals. These tests simulate repository conditions of higher flow rates and can also be used to compare materials and leach solution effects under dynamic conditions. The modified IAEA test is somewhat simpler to use than the one-pass flow and gives adequate results for comparative purposes. The static leach test models the condition of near-zero flow in a repository and provides information on element readsorption and solubility limits. The SPCF test is used to study the effects of flowing solutions at velocities that may be anticipated for geologic groundwaters within breached repositories. These two testing methods, coupled with the use of autoclaves, constitute the current thrust of WRIT leach testing.

  4. Deselenization and detellurization of precious-metal ore concentrates by swelling oxidizing roasting and successive alkaline leaching

    Science.gov (United States)

    Zhang, Fu-yuan; Zheng, Ya-jie; Peng, Guo-min

    2017-02-01

    A new technique of swelling oxidizing roasting and alkaline leaching was proposed for deselenization and detellurization of precious-metal ore concentrates. Alkali-metal and alkaline-earth-metal chlorides and carbonates were preliminarily selected as swelling agents. The roasting removal rate and alkaline leaching rate of selenium and tellurium were investigated, and NaCl was selected as an appropriate swelling agent. Furthermore, the effects of various factors on the selenium gasification rate and leaching rate of selenium and tellurium were investigated. The results show that the selenium gasification rate reaches 88.41% after swelling oxidizing roasting for 2 h at 510°C using an NaCl dosage coefficient of 100 and a sulfuric acid dosage coefficient of 1.3; the amorphous elemental tellurium is completely transformed into TiO2. The roasted product is subjected to alkaline leaching using a 100 g/L NaOH solution, which results in a selenium leaching rate of 10.51%, a total selenium removal rate of 98.92%, and a tellurium leaching rate of 97.64%. In the alkaline leaching residue, the contents of selenium, tellurium, gold, platinum, and palladium are 0.7825%, 5.492%, 8.333%, 0.2587%, and 1.113%, respectively; the precious metals are enriched approximately sixfold.

  5. Aqueous leaching of di-2-ethylhexyl phthalate and "green" plasticizers from poly(vinyl chloride).

    Science.gov (United States)

    Kastner, Joshua; Cooper, David G; Marić, Milan; Dodd, Patrick; Yargeau, Viviane

    2012-08-15

    A method was developed to assess leaching of several poly(vinyl chloride) (PVC) plasticizers in aqueous media using gas chromatography (GC), and compared to a gravimetric standard test method (ASTM Method D1239). The GC method was a more direct measurement of plasticizer concentration in the aqueous phase. The leaching of commercial plasticizers, as well as several series of "green" candidate plasticizers, were assessed as a function of their molecular characteristics and compared to the industry standard PVC plasticizer, di-2-ethylhexyl phthalate (DEHP). It was found that plasticizers containing longer alkyl chains or non-polar branching emanating from polar structural units, increased the hydrophobicity of the molecule and reduced its aqueous leaching rate. Several "green" plasticizer candidates were found to minimize aqueous leaching to rates ten times below that of DEHP; notably dioctyl succinate (DOS), dihexyl maleate (DHM), methyl cyclohexyl diester (MCDE), diethylhexyl succinate (DEHS), hexanediol dibenzoate (C6), and the commercially available Hexamoll® DINCH.

  6. 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.

  7. Kinetic elements in thermophilic-microbial leaching of sulfur from coal. [Sulfolobus acidocaldarius

    Energy Technology Data Exchange (ETDEWEB)

    Chen, C.C.Y.; Skidmore, D.R.

    1988-01-01

    A mechanism found suitable for pyritic sulfur removal from coal by mesophilic organisms has been modified and evaluated for the same reaction by the thermophile: Sulfolobus acidocaldarius. The mechanism as modified includes direct and indirect mechanistic elements whose magnitudes were determined experimentally at leaching conditions with and without microbes. Chemical leaching of pyrite by Fe(III) ions and the chemical oxidation of Fe(II) to Fe(III) were found to contribute significantly to overall conversions at thermophilic temperature (72/degree/C) but not at mesophilic temperature (25-37/degree/C). The model thus constructed fit overall sulfur leaching data well after suitable assumptions had been made for extent of cell attachment; gas (oxygen) transfer rates, sulfur accessibility, and sulfate reprecipitation rates. The resulting equation is useful for process simulation, control and design. Further work is needed to define additional sulfur leaching effects.

  8. 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

  9. Experimental Study on Acid Leaching of a Copper-Cobalt Oxide%某氧化铜钴矿酸浸试验研究

    Institute of Scientific and Technical Information of China (English)

    肖天祥

    2014-01-01

    An oxidized copper and cobalt ore from Congo ( DRC) was tested through stirred acid leaching , agitation reduc-tion-acid leaching and leaching reduction-acid leaching contrast tests .Agitation reduction-acid leaching was identified as the best way , which was not only with fast leaching rate , but also good leaching effect , with the copper , cobalt leaching rate of 93.88%,95.2%respectively.Simultaneously heap leaching (leaching reduction-acid leaching) was also proved as another important way to deal with this ore , with ideal index .%针对刚果(金)某氧化铜钴矿进行了搅拌酸浸、搅拌还原-酸浸和淋滤还原-酸浸对比试验研究,确定了搅拌还原-酸浸是处理这种氧化铜钴矿的最佳方法,不但浸出速度快,而且浸出效果好,铜浸出率达到93.88%,钴浸出率达到95.2%;同时证明了采用堆浸(淋滤还原-酸浸)也是处理这种矿石的另一条重要的途径,也可得到理想的指标。

  10. Oxidative Alkaline leaching of Americium from simulated high-level nuclear waste sludges

    Energy Technology Data Exchange (ETDEWEB)

    Reed, Wendy A.; Garnov, Alexander Yu.; Rao, Linfeng; Nash, Kenneth L.; Bond, Andrew H.

    2004-01-23

    Oxidative alkaline leaching has been proposed to pre-treat the high-level nuclear waste sludges to remove some of the problematic (e.g., Cr) and/or non-radioactive (e.g., Na, Al) constituents before vitrification. It is critical to understand the behavior of actinides, americium and plutonium in particular, in oxidative alkaline leaching. We have studied the leaching behavior of americium from four different sludge simulants (BiPO{sub 4}, BiPO{sub 4 modified}, Redox, PUREX) using potassium permanganate and potassium persulfate in alkaline solutions. Up to 60% of americium sorbed onto the simulants is leached from the sludges by alkaline persulfate and permanganate. The percentage of americium leached increases with [NaOH] (between 1.0 and 5.0 M). The initial rate of americium leaching by potassium persulfate increases in the order BiPO{sub 4} sludge < Redox sludge < PUREX sludge. The data are most consistent with oxidation of Am{sup 3+} in the sludge to either AmO{sub 2}{sup +} or AmO{sub 2}{sup 2+} in solution. Though neither of these species is expected to exhibit long-term stability in solution, the potential for mobilization of americium from sludge samples would have to be accommodated in the design of any oxidative leaching process for real sludge samples.

  11. 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 < 0.05) in the extractable or acid-soluble and reducible fractions. By adopting the proposed approach, the 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.

  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. 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.

  14. Galaxy And Mass Assembly: Estimating galaxy group masses via caustic analysis

    CERN Document Server

    Alpaslan, Mehmet; Driver, Simon; Norberg, Peder; Peacock, John A; Baldry, Ivan; Bland-Hawthorn, Joss; Brough, Sarah; Hopkins, Andrew M; Kelvin, Lee S; Liske, Jochen; Loveday, Jon; Merson, Alexander; Nichol, Robert C; Pimbblet, Kevin

    2012-01-01

    We have generated complementary halo mass estimates for all groups in the Galaxy And Mass Assembly Galaxy Group Catalogue (GAMA G3Cv1) using a modified caustic mass estimation algorithm, originally developed by Diaferio & Geller (1997). We calibrate the algorithm by applying it on a series of 9 GAMA mock galaxy light cones and investigate the effects of using different definitions for group centre and size. We select the set of parameters that provide median-unbiased mass estimates when tested on mocks, and generate mass estimates for the real group catalogue. We find that on average, the caustic mass estimates agree with dynamical mass estimates within a factor of 2 in 90.8 +/- 6.1% groups and compares equally well to velocity dispersion based mass estimates for both high and low multiplicity groups over the full range of masses probed by the G3Cv1.

  15. K-Area Acid/Caustic Basin groundwater monitoring report: First quarter 1992

    Energy Technology Data Exchange (ETDEWEB)

    Thompson, C.Y.

    1992-06-01

    During first quarter 1992, samples from the seven KAC monitoring wells at the K-Area Acid/Caustic Basin of Savannah River Plant 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 Primary Drinking Water Standards (PDWS) and the Savannah River Site (SRS) flagging criteria and turbidity standards during the quarter are discussed in this report. No constituent exceeded the PDWS in the KAC wells at the K-Area Acid/Caustic Basin during first quarter 1992. Total organic halogens exceeded the Flag 2 criterion in wells KAC 6, and 7, and iron exceeded the Flag 2 criterion in well KAC 6. Well KAC 2 was the only well in the KAC well series to exceed the SRS turbidity standard.

  16. Detecting stellar spots through polarimetry observations of microlensing events in caustic-crossing

    CERN Document Server

    Sajadian, Sedighe

    2015-01-01

    In this work, we investigate if gravitational microlensing can magnify the polarization signal of a stellar spot and make it be observable. A stellar spot on a source star of microlensing makes polarization signal through two channels of Zeeman effect and breaking circular symmetry of the source surface brightness due to its temperature contrast. We first explore the characteristics of perturbations in polarimetric microlensing during caustic-crossing of a binary lensing as follows: (a) The cooler spots over the Galactic bulge sources have the smaller contributions in the total flux, although they have stronger magnetic fields. (b) The maximum deviation in the polarimetry curve due to the spot happens when the spot is located near the source edge and the source spot is first entering the caustic whereas the maximum photometric deviation occurs for the spots located at the source center. (c) There is a (partial) degeneracy for indicating spot's size, its temperature contrast and its magnetic induction from the...

  17. 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.

  18. SPHERICAL NONLINEAR PULSES FOR THE SOLUTIONS OF NONLINEAR WAVE EQUATIONS Ⅱ, NONLINEAR CAUSTIC

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    This article discusses spherical pulse like solutions of the system of semilinear wave equations with the pulses focusing at a point and emerging outgoing in three space variables. In small initial data case, it shows that the nonlinearities have a strong effect at the focal point. Scattering operator is introduced to describe the caustic crossing. With the aid of the L∞ norms, it analyzes the relative errors in approximate solutions.

  19. Caustic Injury In Adults – A Study For 3 Year Period

    OpenAIRE

    2016-01-01

    The aim of the study is to present the results of a 3-year clinico-epidemiological investigation of caustic injury in adults. The study includes 43 patients with acute corrosive ingestion, hospitalized in the Toxicology Clinic, University Hospital “N. I. Pirogov”, Sofia, Bulgaria, for the period 01.01. 2010-31.12.2012. The methods used include: clinical observation and examination, clinical laboratory, imaging, and psychiatric methods and tests. 43 patients between the ages of 22 and 82 with ...

  20. 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

  1. Recycling of metal-organic chemical vapor deposition waste of GaN based power device and LED industry by acidic leaching: Process optimization and kinetics study

    Science.gov (United States)

    Swain, Basudev; Mishra, Chinmayee; Kang, Leeseung; Park, Kyung-Soo; Lee, Chan Gi; Hong, Hyun Seon; Park, Jeung-Jin

    2015-05-01

    Recovery of metal values from GaN, a metal-organic chemical vapor deposition (MOCVD) waste of GaN based power device and LED industry is investigated by acidic leaching. Leaching kinetics of gallium rich MOCVD waste is studied and the process is optimized. The gallium rich waste MOCVD dust is characterized by XRD and ICP-AES analysis followed by aqua regia digestion. Different mineral acids are used to find out the best lixiviant for selective leaching of the gallium and indium. Concentrated HCl is relatively better lixiviant having reasonably faster kinetic and better leaching efficiency. Various leaching process parameters like effect of acidity, pulp density, temperature and concentration of catalyst on the leaching efficiency of gallium and indium are investigated. Reasonably, 4 M HCl, a pulp density of 50 g/L, 100 °C and stirring rate of 400 rpm are the effective optimum condition for quantitative leaching of gallium and indium.

  2. 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.

  3. 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.

  4. 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.)

  5. 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.

  6. 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.

  7. 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.

  8. Nitrate Leaching From Grain Maize After Different Tillage Methods and Long/Short Term Cover Cropping

    DEFF Research Database (Denmark)

    Hansen, Elly Møller

    The maize area in northern Europe has increased dramatically during the last 20 years, in Denmark from 19,000 ha in 1990 to 172,000 ha in 2010. Knowledge about nitrogen (N) leaching from maize under temperate coastal climate conditions is sparse. In 2009 an N leaching study was started in a field......, but the effect was insignificant. The effect of tillage and previous N rates were also insignificant but the present use of cover crops had a small but significant decreasing effect on leaching compared to no cover cropping. The cover crop was well established in both years but grew less vigorously during autumn...... due to strong competition from the maize crop. The experiment shows that it is difficult for the perennial ryegrass variety used as cover crop to survive until harvest of grain maize and to reduce leaching substantially....

  9. Alternative Sodium Recovery Technology—High Hydroxide Leaching: FY10 Status Report

    Energy Technology Data Exchange (ETDEWEB)

    Mahoney, Lenna A.; Neiner, Doinita; Peterson, Reid A.; Rapko, Brian M.; Russell, Renee L.; Schonewill, Philip P.

    2011-02-04

    Boehmite leaching tests were carried out at NaOH concentrations of 10 M and 12 M, temperatures of 85°C and 60°C, and a range of initial aluminate concentrations. These data, and data obtained during earlier 100°C tests using 1 M and 5 M NaOH, were used to establish the dependence of the boehmite dissolution rate on hydroxide concentration, temperature, and initial aluminate concentration. A semi-empirical kinetic model for boehmite leaching was fitted to the data and used to calculate the NaOH additions required for leaching at different hydroxide concentrations. The optimal NaOH concentration for boehmite leaching at 85°C was estimated, based on minimizing the amount of Na that had to be added in NaOH to produce a given boehmite conversion.

  10. 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.

  11. Bioleaching combined brine leaching of heavy metals from lead-zinc mine tailings: Transformations during the leaching process.

    Science.gov (United States)

    Ye, Maoyou; Yan, Pingfang; Sun, Shuiyu; Han, Dajian; Xiao, Xiao; Zheng, Li; Huang, Shaosong; Chen, Yun; Zhuang, Shengwei

    2017-02-01

    During the process of bioleaching, lead (Pb) recovery is low. This low recovery is caused by a problem with the bioleaching technique. This research investigated the bioleaching combination of bioleaching with brine leaching to remove heavy metals from lead-zinc mine tailings. The impact of different parameters were studied, including the effects of initial pH (1.5-3.0) and solid concentration (5-20%) for bioleaching, and the effects of sodium chloride (NaCl) concentration (10-200 g/L) and temperature (25 and 50 °C) for brine leaching. Complementary characterization experiments (Sequential extraction, X-ray diffractometer (XRD), scanning electronic microscope (SEM)) were also conducted to explore the transformation of tailings during the leaching process. The results showed that bioleaching efficiency was significantly influenced by initial pH and solid concentration. Approximately 85.45% of iron (Fe), 4.12% of Pb, and 97.85% of zinc (Zn) were recovered through bioleaching in optimum conditions. Increasing the brine concentration and temperature promoted lead recovery. Lead was recovered from the bioleaching residues at a rate of 94.70% at 25 °C and at a rate of 99.46% at 50 °C when the NaCl concentration was 150 g/L. The study showed that bioleaching significantly changed the speciation of heavy metals and the formation and surface morphology of tailings. The metals were mainly bound in stable fractions after bioleaching.

  12. Enhancement of leaching copper by electro-oxidation from metal powders of waste printed circuit board.

    Science.gov (United States)

    Ping, Zhu; ZeYun, Fan; Jie, Lin; Qiang, Liu; Guangren, Qian; Ming, Zhou

    2009-07-30

    Oxidation leaching copper from metal powders of waste printed circuit boards (PCBs) was conducted at room temperature in sulfuric acid solution. The result showed that the copper in metal powders was oxidized by Cu(2+) to form CuCl(2)(-) in the presence of chloride ion without electrochemical oxidation. Then, CuCl(2)(-) was oxidized into CuSO(4) by oxygen derived from the air insufflated into leaching solution. The leaching rate of copper reached 100%. The whole reaction took 5.5h because it was limited by the low solubility of the air in water. In the electro-oxidation conditions, the chloride ion was electro-oxidized into ClO(-), which oxidized CuCl(2)(-) into CuSO(4) and ClO(-) was reduced into Cl(-) itself again at the same time. Since Cl(-) was recycled in the solution not only as a complexing agent but also as an oxidant, which made the reaction speed up to 3.5h to reach 100% leaching rate. Leaching solution was concentrated to crystallize CuSO(4).5H(2)O, and crystal liquor was reused to leach copper from metal powders.

  13. Atmospheric nitrate leached from small forested watersheds during rainfall events: Processes and quantitative evaluation

    Science.gov (United States)

    Osaka, Ken'ichi; Kugo, Tatsuro; Komaki, Naoto; Nakamura, Takashi; Nishida, Kei; Nagafuchi, Osamu

    2016-08-01

    To determine the availability of atmospheric NO3- deposition on forested ecosystems and to understand the interaction between the nitrogen cycle in a forest ecosystem and atmospheric nitrogen input/output, we quantitatively evaluated the atmospheric NO3- passing through forested watersheds by measuring δ18ONO3 leaching during rainfall events in two forest ecosystems (Su-A and Ab-S). Atmospheric NO3- leaching in rainfall events was clearly higher in Ab-S than in Su-A, even for a similar amount of rainfall, which demonstrated that atmospheric NO3- leaching differs among forested watersheds. Our observations suggest that a large part of the atmospheric NO3- leached from the watersheds was derived from surface soil, which was deposited before rainfall events occurred; however, direct atmospheric NO3- leaching via throughfall discharge also contributed, especially at the beginning of rainfall events. In Ab-S, 2.9-37.8% (average = 15.5%) of atmospheric NO3- deposition passed through the watershed, accounting for 3.1-49.8% (average, 26.4%) of the total NO3- leached during rainfall events. The NO3- input was not large, and the NO3- pool and net nitrification rate were small; therefore, nitrogen was not saturated in the soil at Ab-S. Nevertheless, some of the atmospheric NO3- deposition was not assimilated and was leached immediately. Moreover, our observations suggest that the hydrological characteristics of the watersheds, which control the ease of rainwater discharge, strongly influenced the rate of atmospheric NO3- leaching. This suggests that the hydrological characteristics of watersheds influence the availability of atmospheric NO3- deposition in forested ecosystems and the progression of nitrogen saturation.

  14. 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.

  15. 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.

  16. 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.

  17. 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.

  18. 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%.

  19. 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

    2016-11-05

    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.

  20. 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.

  1. Quantifying Arsenic Leaching from Soils Using a Fractional-Derivative Model

    Science.gov (United States)

    Lu, B.; Zhang, Y.; LU, B.

    2015-12-01

    Arsenic leaching from soils can exhibit multiple-rate kinetics due to the heterogeneity nature of the medium, motivating the development of a fractional-order derivative model (FDM). The sorption-desorption process in saturated natural soils may not be limited to be a single rate or can reach equilibrium quickly, even at the laboratory scale. Applications of the FDM show that the multi-rate mass transfer quantifies the multi-stage desorption in Arsenic leaching characterized by the heavy late-time tailing behavior.

  2. 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.

  3. 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.

  4. 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%.

  5. 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.

  6. [Effects of biochar on soil nutrients leaching and potential mechanisms: A review].

    Science.gov (United States)

    Liu, Yu-xue; Lyu, Hao-hao; Shi, Yan; Wang, Yao-feng; Zhong, Zhe-ke; Yang, Sheng-mao

    2015-01-01

    Controlling soil nutrient leaching in farmland ecosystems has been a hotspot in the research field of agricultural environment. Biochar has its unique physical and chemical properties, playing a significant role in enhancing soil carbon storage, improving soil quality and increasing crop yield. As a kind of new exogenous material, biochar has the potential in impacting soil nutrient cycling directly or indirectly, and has profound influences on soil nutrient leaching. This paper analyzed the intrinsic factors affecting how biochar affects soil nutrient leaching, such as the physical and chemical properties of biochar, and the interaction between biochar and soil organisms. Then the latest literatures regarding the external factors, including biochar application rates, soil types, depth of soil layer, fertilization conditions and temporal dynamics, through which biochar influences soil nutrient (especially nitrogen and phosphorus) leaching were reviewed. On that basis, four related action mechanisms were clarified, including direct adsorption of nutrients by biochar due to its micropore structure or surface charge, influencing nutrient leaching through increasing soil water- holding capacity, influencing nutrient cycling through the interaction with soil microbes, and preferential transport of absorbed nutrients by fine biochar particles. At last future research directions for better understanding the interactions between biochar and nutrient leaching in the soil were proposed.

  7. Coordination leaching of tungsten from scheelite concentrate with phosphorus in nitric acid

    Institute of Scientific and Technical Information of China (English)

    张文娟; 杨金洪; 赵中伟; 王文强; 李江涛

    2016-01-01

    A hydrometallurgical process for tungsten extraction and recovery from scheelite is reported. The technology includes leaching scheelite using phosphoric acid as chelating agent in nitric acid solutions, extracting tungsten by solvent extraction and reusing leaching agent. In the leaching process, affecting factors, such as temperature, leaching time, nitric acid and dosage of phosphoric acid, were examined on recovery of tungsten. Results show that more than 97% of tungsten could be extracted under conditions of leaching temperature of 80−90 °C, HNO3 concentration of 3.0−4.0 mol/L, liquild-to-soild ratio of 10:1, H3PO4 dosage of 3 stoichiometric ratio and leaching time of 3 h. Solvent extraction was then employed for the W recovery from the leachate with a organic system of 40%(v/v) N235, 30%(v/v) TBP, and 30%sulfonated kerosene. Approximately 99.93%of W was extracted and ammonium tungstate solution containing 193 g/L W was obtained with a stripping rate of 98.10%under the optimized conditions.

  8. 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.

  9. 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.

  10. [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.

  11. 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.

  12. Leaching Behavior of Heavy Metals from Cement Pastes Using a Modified Toxicity Characteristic Leaching Procedure (TCLP).

    Science.gov (United States)

    Huang, Minrui; Feng, Huajun; Shen, Dongsheng; Li, Na; Chen, Yingqiang; Shentu, Jiali

    2016-03-01

    As the standard toxicity characteristic leaching procedure (TCLP) can not exhaust the acid neutralizing capacity of the cement rotary kiln co-processing solid wastes products which is particularly important for the assessment of the leaching concentrations of heavy metals. A modified TCLP was proposed. The extent of leaching of heavy metals is low using the TCLP and the leaching performance of the different metals can not be differentiated. Using the modified TCLP, however, Zn leaching was negligible during the first 180 h and then sharply increased (2.86 ± 0.18 to 3.54 ± 0.26 mg/L) as the acidity increased (pH cement rotary kiln co-processing products.

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

    Directory of Open Access Journals (Sweden)

    Davide Ciceri

    Full Text Available 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.

  14. Rates of deposition, reserve alteration, and of the leaching of some trace substances in forest ecosystems. Final report. Raten der Deposition, der Vorratsaenderungen und des Austrages einiger Spurenstoffe in Waldoekosystemen. Abschlussbericht

    Energy Technology Data Exchange (ETDEWEB)

    Schultz, R.; Lamersdorf, N.; Heinrichs, H.; Mayer, R.; Ulrich, B.

    1988-01-01

    The investigation related to: the concentrations and flow rates of precipitation in the open field, of precipitation in stands, litter deposition, and seepage waters below the surface humus as well as in a depth of about 1 metre in the ground. Furthermore, trace substances were determined in leaves, wood, bark, fine roots, surface-humus layers and in different ranges of depth of the mineral soil, and inventories were made up from this for the ecosystems investigated. Sites comprise the medium-altitude mountain range as far as the tree species beech, spruce, oak and pine are concerned. Trace materials covered in the analysis are: manganese, cadmium, thallium, lead, bismuth, mercury, silver, beryllium, antimony, vanadium, molybdenum, and boron. To record molybdenum and boron, suitable methods to render these element soluble and for their determination were developed.

  15. 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.

  16. Redox potential (Eh) and anion effects of pyrite (FeS 2 ) leaching at pH 1

    Science.gov (United States)

    Chandra, Anand P.; Gerson, Andrea R.

    2011-11-01

    Pyrite plays the central role in the environmental issue of acid rock drainage. Natural weathering of pyrite results in the release of sulphuric acid which can lead to further leaching of heavy and toxic metals from other associated minerals. Understanding how pyrite reacts in aqueous solution is critical to understanding the natural weathering processes undergone by this mineral. To this end an investigation of the effect of solution redox potential (Eh) and various anions on the rate of pyrite leaching under carefully controlled conditions has been undertaken. Leaching of pyrite has been shown to proceed significantly faster at solution Eh of 900 mV (SHE) than at 700 mV, at pH 1, for the leach media of HCl, H 2SO 4 and HClO 4. The predominant effect of Eh suggests electrochemical control of pyrite leaching with similar mechanism(s) at Eh of 700 and 900 mV albeit with different kinetics. Leach rates at 700 mV were found to decrease according to HClO 4 > HCl > H 2SO 4 while at 900 mV the leach rate order was HCl > HClO 4 > H 2SO 4. Solution Fe 3+ activity is found to continually increase during all leaches; however, this is not accompanied by an increase in leach rate. Synchrotron based photoemission electron microscopy (PEEM) measurements showed a localised distribution of adsorbed and oxidised surface species highlighting that pyrite oxidation and leaching is a highly site specific process mediated by adsorption of oxidants onto specific surface sites. It appears that rates may be controlled, in part, by the propensity of acidic anions to bind to the surface, which varies according to SO42->Cl->ClO4-, thus reducing the reactive or effective surface area. However, anions may also be involved in specific reactions with surface leach products. Stoichiometric dissolution data (Fe/S ratio), XPS and XRD data indicate that the highest leach rates (in HCl media at 900 mV Eh) correlate with relatively lower surface S abundance. Furthermore, there are indications that

  17. 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.

  18. 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.

  19. 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.

  20. Kinetics of gibbsite leaching in sodium hydroxide aqueous solution

    Directory of Open Access Journals (Sweden)

    Pavlović Ljubica J.

    2002-01-01

    Full Text Available In order to study the kinetics and mechanism of the reaction, laboratory leaching was carried out with industrially produced gibbsite γ-Al(OH3 in aqueous solutions containing an excess of sodium hydroxide. The results obtained reaction temperature, duration and base concentration varied. The basic kinetic parameters were determined from: the reaction rate constant k=8.72·107 exp (-74990/RT and the process activation energy in the range Ea=72.5-96.81 kJ/mol.

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

    Energy Technology Data Exchange (ETDEWEB)

    Bradley, D.J.; Harvey, C.O.; Turcotte, R.P.

    1979-08-01

    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), CaCl/sub 2/ (1.66 g/l), NaHCO/sub 3/ (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 CaCl/sub 2/ 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/sup -5/ to 10/sup -8/ g/cm/sup 2//day. 25 figures, 7 tables.

  2. Caustic waterflooding demonstration project: Ranger Zone, Long Beach Unit, Wilmington Field, California. Third annual report, June 1978-May 1979

    Energy Technology Data Exchange (ETDEWEB)

    Mayer, E.H.

    1979-12-01

    A caustic-enhanced waterflooding pilot test is being conducted in the Ranger Reservoir of the Long Beach Unit, Wilmington Field, California. Evaluation of entrapment and entrainment caustic flooding in Ranger Zone cores was continued. The caustic-only (entrapment) core floods failed to demonstrate improved behavior. Based on the unfavorable results of all tests of the entrapment mechanism, further laboratory work and flooding in the pilot with caustic alone have been eliminated from the project's plans. Some of the year's caustic-salt (entrainment) core floods in contrast showed both substantial recovery and WOR improvement. The poorer overall entrainment core flood results obtained in the year may be due to the core material, a smaller preflush volume used or the crude oil employed. Core flood testing where sodium silicate is substituted for some of the sodium hydroxide, was continued. The primary set of caustic water-oil dehydration tests was completed. The test softening of produced waters was completed and the results evaluated; produced water softening was found to be an economically feasible alternative to the use of fresh water. The preflush injection facilities became operational in January 1979 with the pilot's preflush officially begun April 15, 1979. The alkaline injection facility was expanded in scope to permit use of both sodium silicate and sodium hydroxide; its completion in late 1979 is anticipated with the alkaline-salt injection scheduled to begin at that time. The base case reservoir simulator prediction of the pilot under continued waterflooding was completed. This prediction provided the base line from which incremental alkaline flood production will be determined, as the test has now been declared a qualified tertiary enhanced recovery project by DOE's Economic Regulatory Administration. Major well repair/redrill work continued to be necessary exceeding earlier increased cost estimates.

  3. 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.

  4. Recovery of Mn2+, Co2+ and Ni2+ from manganese nodules by redox leaching and solvent extraction

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The recovery of Mn, Co and Ni from deep-sea manganese nodules was conducted by acid oxidative leaching and solvent extraction. The results indicate that pyrrhotite used during leaching can effectively facilitate the leaching out of manganese, cobalt and nickel. The leaching behaviors of Mn, Ni and Co were determined and the influences of temperature, leaching time and sulphuric acid concentration on leaching rate were also investigated. Co and Ni are precipitated from the leaching liquor by adding sodium sulfide into solution with agitation for 2 h at 50 ℃, and the manganese sulphate is obtained by concentrating the resulting solution.By re-dissolving the precipitates of cobalt and nickel, the separation of cobalt and nickel is performed using di(2-ethylhexyl)phosphoric acid (D2EHPA) for impurities elimination with 8 stages at organic-to-aqueous(O/A) volume ratio of 3:5, and 2-ethylhexyl phosphonic acid mono-2-ethylhexyl ester (known as PC88A or P507) for cobalt extraction with 3 stages counter-current operations at O/A volume ratio of 2:3 followed by their scrubbings and strippings, respectively. The final maximum recovery rates for manganese, cobalt and nickel are 85%, 75% and 78%, respectively.

  5. Experimental study of leaching parameters on extracting uranium from a uranium ore%从某铀矿石中回收铀的浸出工艺条件试验研究

    Institute of Scientific and Technical Information of China (English)

    邓锦勋; 李建华; 程威; 周磊

    2012-01-01

    根据某矿床铀矿石的化学组成和矿物形式,分别进行酸法、碱法搅拌浸出及酸法柱浸试验,以探索处理该矿石的工艺条件.试验结果表明:在适当条件下,酸法搅拌授出时,铀浸出率达到88.44%;酸法柱浸时,铀浸出率达到87.63%;碱法搅拌浸出时,铀浸出率较低.综合考虑,工业上宜采用酸法堆浸工艺处理该矿石.%Based on the investigation of the mineral form and chemical compositions, the processing method and leaching parameters were selected through acid stirring leaching, alkaline stirring leaching and acid column leaching experiments. Under suitable conditions, the leaching rate of acid stirring leaching can reach 88. 44%, and leaching rate of acid column leaching is 87. 65%. Alkaline stirring leaching is not suitable for the ore for its low leaching rate. In the final analysis acid heap leaching is available for extracting uranium from the uranium ore in the industrial production.

  6. 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.

  7. Origami constraints on the initial-conditions arrangement of dark-matter caustics and streams

    CERN Document Server

    Neyrinck, Mark C

    2012-01-01

    In a cold-dark-matter universe, cosmological structure formation proceeds in rough analogy to origami folding. Dark matter occupies a three-dimensional 'sheet,' non-intersecting in six-dimensional velocity-position phase space. At early times, the sheet was flat like an origami sheet, i.e. velocities were essentially zero. The present paper further illustrates this analogy, and identifies a result of origami mathematics that applies to cosmology. We define caustics in the initial conditions Lagrangian space) as surfaces in this sheet, along which the sheet has folded. The regions outlined by these caustics, which we call streams, may be colored according to the two possible orientations of initial basis vectors, a two-coloring such that adjacent streams are not colored the same. While this may not have clear observational consequences, it is a severe restriction on connectivity, since there are no bounds on the number of colors required to color a general arrangement of three-dimensional regions. Then, measur...

  8. 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.

  9. 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.

  10. 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.

  11. 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

  12. Column leaching from biomass combustion ashes

    DEFF Research Database (Denmark)

    Maresca, Alberto; Astrup, Thomas Fruergaard

    2015-01-01

    The utilization of biomass combustion ashes for forest soil liming and fertilizing has been addressed in literature. Though, a deep understanding of the ash chemical composition and leaching behavior is necessary to predict potential benefits and environmental risks related to this practice...

  13. Duality properties of Gorringe Leach equations

    Science.gov (United States)

    Grandati, Yves; Bérard, Alain; Mohrbach, Hervé

    2009-02-01

    In the category of motions preserving the angular momentum direction, Gorringe and Leach exhibited two classes of differential equations having elliptical orbits. After enlarging slightly these classes, we show that they are related by a duality correspondence of the Arnold Vassiliev type. The specific associated conserved quantities (Laplace Runge Lenz vector and Fradkin Jauch Hill tensor) are then dual reflections of each other.

  14. 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

  15. Gold and Silver Extraction from Leach Solutions

    OpenAIRE

    Bagdaulet K. Kenzhaliyev; Renata R. Iskhakova; Zamzagul D. Dosymbaeva; Esen N. Sulejmenov

    2014-01-01

    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.

  16. 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.

  17. 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.

  18. 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.

  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. 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.

  2. Stability and leaching of cobalt smelter fly ash

    DEFF Research Database (Denmark)

    Vítková, Martina; Hyks, Jiri; Ettler, Vojtěch

    2013-01-01

    The leaching behaviour of fly ash from a Co smelter situated in the Zambian Copperbelt was studied as a function of pH (5–12) using the pH-static leaching test (CEN/TS 14997). Various experimental time intervals (48h and 168h) were evaluated. The leaching results were combined with the ORCHESTRA ...

  3. Recovery of valuable metals from cathodic active material of spent lithium ion batteries: Leaching and kinetic aspects.

    Science.gov (United States)

    Meshram, Pratima; Pandey, B D; Mankhand, T R

    2015-11-01

    This work is focussed on the processing of cathodic active material of spent lithium ion batteries (LIBs) to ensure resource recovery and minimize environmental degradation. The sulfuric acid leaching of metals was carried out for the recovery of all the valuable metals including nickel and manganese along with the frequently targeted metals like lithium and cobalt. The process parameters such as acid concentration, pulp density, time and temperature for the leaching of metals from the cathode powder containing 35.8% Co, 6.5% Li, 11.6% Mn and 10.06% Ni, were optimized. Results show the optimized leach recovery of 93.4% Li, 66.2% Co, 96.3% Ni and 50.2% Mn when the material was leached in 1M H2SO4 at 368 K and 50 g/L pulp density for 240 min. The need of a reductant for improved recovery of cobalt and manganese has been explained by the thermodynamic analysis (Eh-pH diagram) for these metals. Leaching of the valuable metals was found to follow the logarithmic rate law controlled by surface layer diffusion of the lixiviant reacting with the particles. The mode of leaching of the metals from the spent LIBs was further examined by chemical analysis of the samples at various stage of processing which was further corroborated by characterizing the untreated sample and the leach residues by XRD phase identification and the SEM-EDS studies.

  4. Multiple heavy metals extraction and recovery from hazardous electroplating sludge waste via ultrasonically enhanced two-stage acid leaching.

    Science.gov (United States)

    Li, Chuncheng; Xie, Fengchun; Ma, Yang; Cai, Tingting; Li, Haiying; Huang, Zhiyuan; Yuan, Gaoqing

    2010-06-15

    An ultrasonically enhanced two-stage acid leaching process on extracting and recovering multiple heavy metals from actual electroplating sludge was studied in lab tests. It provided an effective technique for separation of valuable metals (Cu, Ni and Zn) from less valuable metals (Fe and Cr) in electroplating sludge. The efficiency of the process had been measured with the leaching efficiencies and recovery rates of the metals. Enhanced by ultrasonic power, the first-stage acid leaching demonstrated leaching rates of 96.72%, 97.77%, 98.00%, 53.03%, and 0.44% for Cu, Ni, Zn, Cr, and Fe respectively, effectively separated half of Cr and almost all of Fe from mixed metals. The subsequent second-stage leaching achieved leaching rates of 75.03%, 81.05%, 81.39%, 1.02%, and 0% for Cu, Ni, Zn, Cr, and Fe that further separated Cu, Ni, and Zn from mixed metals. With the stabilized two-stage ultrasonically enhanced leaching, the resulting over all recovery rates of Cu, Ni, Zn, Cr and Fe from electroplating sludge could be achieved at 97.42%, 98.46%, 98.63%, 98.32% and 100% respectively, with Cr and Fe in solids and the rest of the metals in an aqueous solution discharged from the leaching system. The process performance parameters studied were pH, ultrasonic power, and contact time. The results were also confirmed in an industrial pilot-scale test, and same high metal recoveries were performed.

  5. 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).

  6. 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).

  7. Leaching and mechanical properties of cabal glasses developed as matrices for immobilization high-level wastes

    Science.gov (United States)

    Ezz-Eldin, F. M.

    2001-10-01

    This paper discusses the leaching behavior of simulated high-level-waste cabal glass (CaO-B 2O 3-Al 2O 3) as a bulk specimen. During leach tests, the glass is immersed in either deionized water or in groundwater for up to 57 days at 70°C. Based on the results, mechanisms observed with the leaching of the glass in deionized water or groundwater are discussed. Three factors, i.e., time of immersion, type of leaching solution and irradiation effect, are extensively studied. The corrosion was found to be linear with time in the limit of investigation (1-57 days) but with different rates depending on the type of solution and glass composition. Effects of γ-irradiation on the glass together with groundwater were found to decrease the glass durability. The evolution of the damage on mechanical and physical properties of the glass before and after leaching or irradiation was also discussed. The addition of waste oxide changes the properties of the glass matrix, so the influence of the guest oxides on the properties of host materials is also discussed.

  8. 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.

  9. 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.

  10. Phosphorus leaching from soils amended with thermally gasified piggery waste ash

    DEFF Research Database (Denmark)

    Kuligowski, Ksawery; Poulsen, Tjalfe

    2009-01-01

    from anaerobically digested, thermally gasified (GA) and incinerated (IA) piggery waste has been tested using water loads ranging from 0.1 to 200 ml g−1. Leaching of P from soil columns amended with GA was investigated for one P application rate (205 kg P ha−1 corresponding to 91 mg P kg−1 soil dry...

  11. Evaluation of soil temperature effect on herbicide leaching potential into groundwater in the Brazilian Cerrado.

    Science.gov (United States)

    Paraíba, Lourival Costa; Cerdeira, Antonio Luiz; da Silva, Enio Fraga; Martins, João Souza; Coutinho, Heitor Luiz da Costa

    2003-12-01

    The effect of annual variations in the daily average soil temperatures, at different depths, on the calculation of pesticide leaching potential indices is presented. This index can be applied to assess the risk of groundwater contamination by a pesticide. It considers the effects of water table depth, daily recharge net rate, pesticide sorption coefficient, and degradation rate of the pesticide in the soil. The leaching potential index is frequently used as a screening indicator in pesticide groundwater contamination studies, and the temperature effect involved in its calculation is usually not considered. It is well known that soil temperature affects pesticide degradation rates, air-water partition coefficient, and water-soil partition coefficient. These three parameters are components of the attenuation and retardation factors, as well as the leaching potential index, and contribute to determine pesticide behavior in the environment. The Arrhenius, van't Hoff, and Clausius-Clapeyron equations were used in this work to estimate the soil temperature effect on pesticide degradation rate, air-water partition coefficient, and water-soil partition coefficient, respectively. The relationship between leaching potential index and soil temperature at different depths is presented and aids in the understanding of how potential pesticide groundwater contamination varies on different climatic conditions. Numerical results will be presented for 31 herbicides known to be used in corn and soybean crops grown on the municipality of São Gabriel do Oeste, Mato Grosso do Sul State, Brazil.

  12. Colorimetric detection of trace copper ions based on catalytic leaching of silver-coated gold nanoparticles.

    Science.gov (United States)

    Lou, Tingting; Chen, Lingxin; Chen, Zhaopeng; Wang, Yunqing; Chen, Ling; Li, Jinhua

    2011-11-01

    A colorimetric, label-free, and nonaggregation-based silver coated gold nanoparticles (Ag/Au NPs) probe has been developed for detection of trace Cu(2+) in aqueous solution, based on the fact that Cu(2+) can accelerate the leaching rate of Ag/Au NPs by thiosulfate (S(2)O(3)(2-)). The leaching of Ag/Au NPs would lead to dramatic decrease in the surface plasmon resonance (SPR) absorption as the size of Ag/Au NPs decreased. This colorimetric strategy based on size-dependence of nanoparticles during their leaching process provided a highly sensitive (1.0 nM) and selective detection toward Cu(2+), with a wide linear detection range (5-800 nM) over nearly 3 orders of magnitude. The cost-effective probe allows rapid and sensitive detection of trace Cu(2+) ions in water samples, indicating its potential applicability for the determination of copper in real samples.

  13. 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.

  14. 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.

  15. 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.

  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. 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.

  19. Mechanochemical leaching of chalcopyrite concentrate by sulfuric acid

    Science.gov (United States)

    Mohammadabad, Farhad Khorramshahi; Hejazi, Sina; khaki, Jalil Vahdati; Babakhani, Abolfazl

    2016-04-01

    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 determine 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.

  20. 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.

  1. 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

  2. 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.

  3. Probe of Multielectron Dynamics in Xenon by Caustics in High-Order Harmonic Generation

    Science.gov (United States)

    Faccialà, D.; Pabst, S.; Bruner, B. D.; Ciriolo, A. G.; De Silvestri, S.; Devetta, M.; Negro, M.; Soifer, H.; Stagira, S.; Dudovich, N.; Vozzi, C.

    2016-08-01

    We investigated the giant resonance in xenon by high-order harmonic generation spectroscopy driven by a two-color field. The addition of a nonperturbative second harmonic component parallel to the driving field breaks the symmetry between neighboring subcycles resulting in the appearance of spectral caustics at two distinct cutoff 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 Letter 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 us to see features that are normally not accessible and to obtain a good agreement between the experimental results and the theoretical predictions.

  4. K-Area/Caustic Basin Groundwater Monitoring Report. Second quarter 1993

    Energy Technology Data Exchange (ETDEWEB)

    Thompson, C.Y.

    1993-09-01

    During second quarter 1993, samples from the KAC monitoring wells at the K-Area Acid/Caustic Basin were collected and analyzed for indicator parameters, groundwater quality parameters, parameters indicating suitability as drinking water, 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. No analytes exceeded the final PDWS during second quarter 1993. Aluminum exceeded its Flag 2 criterion in wells KAC 6, 7, and 9. Iron exceeded the Flag 2 criterion in wells KAC 6 and 7, and specific conductance exceeded the Flag 2 criterion in well KAC 9. No samples exceeded the SRS turbidity standard.

  5. Free-fall accretion and emitting caustics in wind-fed X-ray sources

    Science.gov (United States)

    Illarionov, Andrei F.; Beloborodov, Andrei M.

    2001-05-01

    In wind-fed X-ray binaries the accreting matter is Compton-cooled and falls freely on to the compact object. The matter has a modest angular momentum l and accretion is quasi-spherical at large distances from the compact object. Initially small non-radial velocities grow in the converging supersonic flow and become substantial in the vicinity of the accretor. The streamlines with l>(GMR*)1/2 (where M and R* are the mass and radius of the compact object) intersect outside R* and form a two-dimensional caustic which emits X-rays. The streamlines with low angular momentum, lorbital phase of the binary. The accretor then appears as a `Moon-like' X-ray source.

  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 lycopene efficiently from tomato processing byproducts.

  7. 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.

  8. 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.

  9. 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.

  10. 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...

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. Sorption kinetics and its effects on retention and leaching.

    Science.gov (United States)

    de Wilde, Tineke; Mertens, Jan; Spanoghe, Pieter; Ryckeboer, Jaak; Jaeken, Peter; Springael, Dirk

    2008-06-01

    Sorption of pesticides to substrates used in biopurification systems is important as it controls the system's efficiency. Ideally, pesticide sorption should occur fast so that leaching of the pesticide in the biopurification system is minimized. Although modeling of pesticide transport commonly assumes equilibrium, this may not always be true in practice. Sorption kinetics have to be taken into account. This study investigated the batch sorption kinetics of linuron, isoproturon, metalaxyl, isoxaben and lenacil on substrates commonly used in a biopurification system, i.e. cow manure, straw, willow chopping, sandy loam soil, coconut chips, garden waste compost and peat mix. The first-order sorption kinetics model was fitted to the observed pesticide concentrations versus time resulting in an estimated kinetic rate constant alpha. Sorption appeared to be fast for the pesticides linuron and isoxaben, pesticides which were classified as immobile, while less mobile pesticides displayed an overall slower sorption. However, the substrate does not seem to be the main parameter influencing the sorption kinetics. Coconut chips, which is a substrate with a high organic matter content showed slow sorption for most of the pesticides. The effect of different estimated alpha values on the breakthrough of pesticides through a biopurification system was evaluated using the HYDRUS 1D model. Significant differences in leaching behavior were observed as a result of the obtained differences in sorption kinetics.

  16. 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.

  17. Duality properties of Gorringe-Leach equations

    OpenAIRE

    Grandati, Yves; Berard, Alain; Mohrbach, Herve

    2004-01-01

    International audience; In the category of motions preserving the angular momentum's direction, Gorringe and Leach exhibited two classes of differential equations having elliptical orbits. After enlarging slightly these classes, we show that they are related by a duality correspondence of the Arnold-Vassiliev type. The specific associated conserved quantities (Laplace-Runge-Lenz vector and Fradkin-Jauch-Hill tensor) are then dual reflections one of the other

  18. Duality properties of Gorringe-Leach equations

    CERN Document Server

    Grandati, Yves; Mohrbach, Herve

    2007-01-01

    In the category of motions preserving the angular momentum's direction, Gorringe and Leach exhibited two classes of differential equations having elliptical orbits. After enlarging slightly these classes, we show that they're related by a duality correspondence of the Arnold-Vassiliev type. The specific associated conserved quantities (Laplace-Runge-Lenz vector and Fradkin-Jauch-Hill tensor) are then dual reflections one of the other.

  19. 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.

  20. Effect of key parameters on the selective acid leach of nickel from mixed nickel-cobalt hydroxide

    Science.gov (United States)

    Byrne, Kelly; Hawker, William; Vaughan, James

    2017-01-01

    Mixed nickel-cobalt hydroxide precipitate (MHP) is a relatively recent intermediate product in primary nickel production. The material is now being produced on a large scale (approximately 60,000 t/y Ni as MHP) at facilities in Australia (Ravensthorpe, First Quantum Minerals) and Papua New Guinea (Ramu, MCC/Highlands Pacific). The University of Queensland Hydrometallurgy research group developed a new processing technology to refine MHP based on a selective acid leach. This process provides a streamlined route to obtaining a high purity nickel product compared with conventional leaching / solvent extraction processes. The selective leaching of nickel from MHP involves stabilising manganese and cobalt into the solid phase using an oxidant. This paper describes a batch reactor study investigating the timing of acid and oxidant addition on the rate and extent of nickel, cobalt, manganese leached from industrial MHP. For the conditions studied, it is concluded that the simultaneous addition of acid and oxidant provide the best process outcomes.

  1. Pitting Behavior of L415 Pipeline Steel in Simulated Leaching Liquid Environment

    Science.gov (United States)

    Wan, H. X.; Yang, X. J.; Liu, Z. Y.; Song, D. D.; Du, C. W.; Li, X. G.

    2016-12-01

    The corrosion behavior and laws of the west-east gas pressure pipeline of L415 steel were studied in simulated leaching liquid. The failure of the L415 steel during the pressure testing process was investigated using electrochemical polarization, electrochemical impedance spectroscopy, and immersion test. The corrosion rate of the L415 steel increased with ion concentration in the leaching liquid. This rate reached about 0.8 mm a-1 and belonged to the severe corrosion grade. Pitting corrosion was observed in various simulated solutions with different aggressive species concentrations. The original ion concentration in the leaching liquid (1×) is the key factor influencing pitting initiation and development. Pitting showed easy nucleation, and its growth rate was relatively slow, in the basic simulating solution of the leach liquid (i.e., the ion content is compactable to the real condition in the rust on the inner steel pipe surface). Pitting was also highly sensitive and easily grew in the solution with doubled ion concentration in the basic simulating solution (2×). A uniform corrosion, instead of pitting, mainly occurred when the ion concentration was up to 10× of the basic solution.

  2. Conversion of results from ash leaching in laboratory to field conditions. Final report; Oeversaettning av resultat fraan asklaknings foersoek i laboratorium till faeltfoerhaallanden. Slutrapport

    Energy Technology Data Exchange (ETDEWEB)

    Westling, Olle; Larsson, Per-Erik [Swedish Environmental Research Inst., Goeteborg (Sweden)

    2004-09-01

    The leaching of different elements from stabilised wood ash used for recycling of nutrients to forest soil was investigated and compared in both laboratory and field experiments. The aim was to evaluate if a simplified laboratory method can be used to describe the leaching in field conditions in a realistic way. The laboratory leaching study was performed by mixing wood ash and distilled water, adjusted to pH 4.2. The leachate was poured off after 24 h and new solution added. The leachate was analysed for pH, acid neutralising capacity and base cations. This procedure, with daily change of solution, continued for 30 days, simulating the time of a forest rotation (80-100 years). The field study used wood ash in litter bags placed under the humus layer in a spruce forest with and without contact with mycorrhiza. Litterbags were removed and analysed after 6, 12, 18 and 30 months. The leaching of wood ash and crushed limestone were also compared in both the laboratory and the field study. The weight loss of wood ash and limestone after 30 days in the laboratory study (simulating a forest rotation) varied between 20 and 35%, indicating a very long time for complete weathering. The weight loss in the field study after 30 months (8-22%) also indicated a long weathering time. The leaching of wood ash during the 30-month field experiment showed a variation in the leaching pattern for different elements. The leaching of calcium increased in the beginning of the study, followed by a decrease. The leaching of magnesium was relatively linear in contrast to potassium, with a fast leaching of 35 to 40% of the original content after 6 months. The experiment with leaching of wood ash and crushed limestone during field conditions with and without contact with mycorrhiza showed no significant differences between the treatments. The comparison between laboratory and field leaching generally showed that the different methods describe the leaching rate of base cations in a similar way

  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. 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

  5. Leaching Pretreatments for Improving Biomass Quality: Feedstocks, Solvents, and Extraction Modeling

    Science.gov (United States)

    Yu, Chao Wei

    In this research, a systematic study was conducted to quantify the inorganic and organic compounds leached from rice straw, wheat straw, corn stover, switchgrass, Jose Tall Wheatgrass, Douglas fir, and Miscanthus with water, and to evaluate the feedstock quality and characteristics of leached solids for thermal process applications. Leaching feedstocks with water at ambient temperature with a 20 L/kg (dry matter) ratio for 2 hours greatly increased the ash fusion temperature of rice straw (from 1050°C to above 1550°C) and wheat straw (from 900°C to 1250°C), but the treatment only increased the ash fusion temperature of corn stover from 900°C to 950°C. Miscanthus had relatively good initial feedstock quality and leaching may not prove necessary for this feedstock in thermal systems. Leaching also changed the combustion kinetics of biomass by increasing the initial degradation temperature of most feedstocks from originally between 165°C and 186°C to between 180°C and 250°C depending on feedstock. Moreover, leaching increased the maximum rate of weight loss of feedstock by 11% to 54% and increased the corresponding temperatures for peak loss up to 34°C. Leaching removed a sizeable fraction of organic compounds (between 2% and 12% of dry matter). These organic extracts were identified as mostly sugars and acids which might be valuable co-products. Moisture contents of feedstocks after leaching were typically high, ranging between 68 and 81% wet basis. A dewatering step is generally required prior to using the leached biomass for thermochemical conversion. Solvents with ability to dissolve ion-exchangeable, organically associated, and acid soluble metals can further remove non-water soluble metals from biomass and may also improve feedstock quality. In a solvent evaluation, corn stover and wheat straw were leached with water, 1M ammonium acetate, 1M HCl, 100% methanol, 50% methanol, 100% ethanol, and 50% ethanol, and leached solids and leachate were

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. Microstructure and leaching durability of glass composite wasteforms for spent clinoptilolite immobilisation

    Science.gov (United States)

    Juoi, J. M.; Ojovan, M. I.; Lee, W. E.

    2008-01-01

    Simulated spent Cs-clinoptilolite waste was immobilised in a monolithic glass composite material (GCM) produced by a pressureless sintering at 750 °C for 2 h duration. The effects of waste loading from 1:1 up to 1:10 glass to waste volume ratio (37 up to 88 wt%) on the GCM wasteform microstructure and leaching properties were analysed. The open porosity ranged between 0.84 and ˜13.2 % for the highest waste load. Significant changes occurred in the microstructure, phases present and wasteform durability at different waste loading. At waste loading up to 73 wt% of spent clinoptilolite, the GCM microstructure consists of several crystalline phases (clinoptilolite, sodalite, wollastonite and CsCl) that were fully encapsulated by a glass matrix. This leads to a low normalized leaching rate of Cs (remaining below 6.35 × 10 -6 g/cm 2 day in a GCM with 73 wt% waste) during a leaching test for 7 days conducted using ASTM C1220-98. In GCM's with waste loading exceeding 73 wt%, the crystalline phases present (clinoptilolite and CsCl) were not fully encapsulated by the glass matrix hence the normalized leaching rate of Cs was as high as 9.06 × 10 -4 g/cm 2 day at waste loading of ⩾80 wt%.

  11. Microstructure and leaching durability of glass composite wasteforms for spent clinoptilolite immobilisation

    Energy Technology Data Exchange (ETDEWEB)

    Juoi, J.M. [Immobilisation Science Laboratory, University of Sheffield, Sir Robert Hadfield Building, Mappin Street, Sheffield S1 3JD (United Kingdom)], E-mail: j.juoi@sheffield.ac.uk; Ojovan, M.I. [Immobilisation Science Laboratory, University of Sheffield, Sir Robert Hadfield Building, Mappin Street, Sheffield S1 3JD (United Kingdom); Lee, W.E. [Department of Materials, Imperial College London, S Kensington Campus, London SW7 2AZ (United Kingdom)

    2008-01-31

    Simulated spent Cs-clinoptilolite waste was immobilised in a monolithic glass composite material (GCM) produced by a pressureless sintering at 750 deg. C for 2 h duration. The effects of waste loading from 1:1 up to 1:10 glass to waste volume ratio (37 up to 88 wt%) on the GCM wasteform microstructure and leaching properties were analysed. The open porosity ranged between 0.84 and {approx}13.2 % for the highest waste load. Significant changes occurred in the microstructure, phases present and wasteform durability at different waste loading. At waste loading up to 73 wt% of spent clinoptilolite, the GCM microstructure consists of several crystalline phases (clinoptilolite, sodalite, wollastonite and CsCl) that were fully encapsulated by a glass matrix. This leads to a low normalized leaching rate of Cs (remaining below 6.35 x 10{sup -6} g/cm{sup 2} day in a GCM with 73 wt% waste) during a leaching test for 7 days conducted using ASTM C1220-98. In GCM's with waste loading exceeding 73 wt%, the crystalline phases present (clinoptilolite and CsCl) were not fully encapsulated by the glass matrix hence the normalized leaching rate of Cs was as high as 9.06 x 10{sup -4} g/cm{sup 2} day at waste loading of {>=}80 wt%.

  12. 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.

  13. 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)

  14. 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)

  15. 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.

  16. 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.

  17. 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

  18. Highly efficient and selective leaching of silver from electronic scrap in the base-activated persulfate - ammonia system.

    Science.gov (United States)

    Hyk, Wojciech; Kitka, Konrad

    2017-02-01

    A system composed of persulfate salt and ammonia in highly alkaline aqueous solution is developed and examined for leaching metallic silver from elements of the electronic waste materials (e-scrap). Strong base activates persulfate ions providing in situ generation of highly reactive oxygen molecules. The oxidized metal forms then well soluble complex ions with ammonia ligands. The kinetic studies of the leaching process were performed for pure metallic silver. They revealed that the efficiency of the process is affected by the type of the persulfate salt. By employing potassium persulfate one obtains significantly (more than 50% for silver plates and more than 100% for silver powder) increased efficiency of silver dissolution compared to the solution composed of either sodium or ammonium persulfates. In the range of persulfate concentrations between 0.02 and 0.23mol/L the apparent reaction order with respect to the persulfate concentration was similar for all persulfate salts and was estimated to be around 0.5. The room temperature (22±2°C) seems to be an optimal temperature for the leaching process. An increase in the temperature resulted in the significant drop in the silver dissolution rate due to the decreased solubility of oxygen. Based on these results a possible mechanism of dissolving silver is discussed and the optimal composition of the leaching solution is formulated. The obtained formulation of the leaching solution was applied for the extraction of silver coatings of Cu-based e-waste scrap and the obtained results revealed an important effect of copper in the mechanism of the leaching process. The regression analysis of the leaching curve indicated that each gram of base-activated potassium persulfate under the specified conditions may leach almost 100mg of silver coatings in a form of well soluble diamminesilver (I) complex. The silver complex can be relatively easy reduced to metallic silver. The method developed is relatively cheap, low toxic and

  19. 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.

  20. Nitrate leaching in a winter wheat-summer maize rotation on a calcareous soil as affected by nitrogen and straw management

    Science.gov (United States)

    Huang, Tao; Ju, Xiaotang; Yang, Hao

    2017-02-01

    Nitrate leaching is one of the most important pathways of nitrogen (N) loss which leads to groundwater contamination or surface water eutrophication. Clarifying the rates, controlling factors and characteristics of nitrate leaching is the pre-requisite for proposing effective mitigation strategies. We investigated the effects of interactions among chemical N fertilizer, straw and manure applications on nitrogen leaching in an intensively managed calcareous Fluvo-aquic soil with winter wheat-summer maize cropping rotations on the North China Plain from October 2010 to September 2013 using ceramic suction cups and seepage water calculations based on a long-term field experiment. Annual nitrate leaching reached 38–60 kg N ha‑1 from conventional N managements, but declined by 32–71% due to optimum N, compost manure or municipal waste treatments, respectively. Nitrate leaching concentrated in the summer maize season, and fewer leaching events with high amounts are the characteristics of nitrate leaching in this region. Overuse of chemical N fertilizers, high net mineralization and nitrification, together with predominance of rainfall in the summer season with light soil texture are the main controlling factors responsible for the high nitrate leaching loss in this soil-crop-climatic system.

  1. Nitrate leaching in a winter wheat-summer maize rotation on a calcareous soil as affected by nitrogen and straw management

    Science.gov (United States)

    Huang, Tao; Ju, Xiaotang; Yang, Hao

    2017-01-01

    Nitrate leaching is one of the most important pathways of nitrogen (N) loss which leads to groundwater contamination or surface water eutrophication. Clarifying the rates, controlling factors and characteristics of nitrate leaching is the pre-requisite for proposing effective mitigation strategies. We investigated the effects of interactions among chemical N fertilizer, straw and manure applications on nitrogen leaching in an intensively managed calcareous Fluvo-aquic soil with winter wheat-summer maize cropping rotations on the North China Plain from October 2010 to September 2013 using ceramic suction cups and seepage water calculations based on a long-term field experiment. Annual nitrate leaching reached 38–60 kg N ha−1 from conventional N managements, but declined by 32–71% due to optimum N, compost manure or municipal waste treatments, respectively. Nitrate leaching concentrated in the summer maize season, and fewer leaching events with high amounts are the characteristics of nitrate leaching in this region. Overuse of chemical N fertilizers, high net mineralization and nitrification, together with predominance of rainfall in the summer season with light soil texture are the main controlling factors responsible for the high nitrate leaching loss in this soil-crop-climatic system. PMID:28176865

  2. 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

  3. 常压富氧浸出在黄金氰化生产中的应用%Application of Atmospheric Oxygen Enriched Leaching in Gold Cyanide Production

    Institute of Scientific and Technical Information of China (English)

    杨俊彦; 国洪柱; 陈萍; 徐忠敏

    2016-01-01

    针对某氰化厂金精矿,为进一步提高氰化浸出率,采用常压富氧浸出工艺,进行了小型、半工业、工业3种规模的试验研究。小型试验结果表明,富氧浸出工艺能提高金浸出率0.30%;半工业试验结果表明,采用富氧浸出工艺后,金浸出速度明显高于空气浸出工艺组。通过3个月工业试验结果表明,与现场空气浸出工艺组对比,富氧浸出工艺能明显提高浸出速度,提高金浸出率0.18%,浸渣中银品位降低5×10-6~6×10-6,年增加经济效益490.10万元,取得了良好经济技术指标,该研究成果为在黄金企业推广应用提供借鉴,推动了氰化浸出技术的发展。%According to the gold concentrate of a cyanide plant,in order to further enhance the rate of cyanide leaching,the minitype,semi-industrial and industrial experimental study were conducted under atmospheric oxygen enriched leaching technology in this study.The results of minitype test showed that the rich oxygen leaching process can increase the leaching rate by 0.3% ,and the semi-industrial test displayed that the gold leaching rate was obviously higher than that obtained by the air leaching.In addition,industrial test results during three months demonstrated that the oxygen rich leaching can improve the leaching speed compared to the technique of air leaching,and significantly increase the leaching rate by 0.18%.With the oxygen rich leaching,the silver grade in leach residues can be even low to 5×10-6~6×10-6,and it increased economic benefits by 4.9 million yuan per year.Hence,the research results in the present work provide reference for application in the gold enterprises,and will promote the development of the cyanide leaching technology in the future.

  4. Leaching studies for metals recovery from waste printed wiring boards

    Science.gov (United States)

    Luyima, Alex; Shi, Honglan; Zhang, Lifeng

    2011-08-01

    The leaching behavior of most metals present in printed wiring boards is evaluated, aiming at its recycling by hydrometallurgy. Two leaching reagents (nitric acid and aqua regia) are compared. The effects of acid concentration, particle size of sample, leaching time, and temperature are examined. The results reveal that small particle size and a combination of both nitric acid and aqua regia are capable of dissolving most of the metals content of printed wiring boards.

  5. 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.

  6. 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.

  7. Leaching of Vanadium From Petroleum Coke by Alkali Solution%从高钒石油焦中碱浸钒

    Institute of Scientific and Technical Information of China (English)

    杨利群; 张亚莉; 化茜; 于先进

    2013-01-01

    研究了用碱法从氧化后的高钒石油焦中浸出钒,进行了槽浸、柱浸、堆浸试验。试验结果表明:在温度110℃、液固体积质量比6∶1、NaO H质量浓度150 g/L最佳条件下,槽浸钒浸出率为67.89%;在NaO H质量浓度为75 g/L时,槽浸钒浸出率最大为53.76%;在 NaO H 质量浓度为75 g/L时,堆浸钒浸出率最大为47.97%。%Leaching of vanadium from high vanadium oxidized petroleum coke using alkali solution was investigated .The tank-leaching ,column-leaching and heap-leaching tests were conducted .The results show that under the optimal temperature of 110 ℃ ,the ratio between liquid volume and solid mass of 6∶1 ,NaOH concentration of 150 g/L ,the tank-leaching rate of vanadium reaches 67 .89% .Under the condition of NaOH concentration of 75 g/L ,the volumn-leaching rate of vanadium reaches 53 .76% . The heap-leaching rate of vanadium reaches 47 .97% under the NaOH concentration of 75 g/L .

  8. Comparative evaluation of microbial and chemical leaching processes for heavy metal removal from dewatered metal plating sludge.

    Science.gov (United States)

    Bayat, Belgin; Sari, Bulent

    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 3l 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 degrees 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 degrees 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

  9. 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)

  10. Long-term leaching from MSWI air-pollution-control residues: Leaching characterization and modeling

    DEFF Research Database (Denmark)

    Hyks, Jiri; Astrup, Thomas; Christensen, Thomas Højlund

    2009-01-01

    Long-term leaching of Ca, Fe, Mg, K, Na, S, Al, As, Ba, Cd, Co, Cr, Cu, Hg, Mn, Ni, Pb, Zn, Mo, Sb, Si, Sri, Sr, Ti, V, P, Cl, and dissolved organic carbon from two different municipal solid waste incineration (MSWI) air-pollution-control residues was monitored during 24 months of column...

  11. 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.

  12. Simulations of sonic boom ray tube area fluctuations for propagation through atmospheric turbulence including caustics via a Monte Carlo method

    Science.gov (United States)

    Sparrow, Victor W.; Pierce, Allan D.

    1992-01-01

    A theory which gives statistical predictions for how often sonic booms propagating through the earth's turbulent boundary layer will encounter caustics, given the spectral properties of the atmospheric turbulence, is outlined. The theory is simple but approximately accounts for the variation of ray tube areas along ray paths. This theory predicts that the variation of ray tube areas is determined by the product of two similar area factors, psi (x) and phi (x), each satisfying a generic harmonic oscillator equation. If an area factor increases the peak acoustic pressure decreases, and if the factor decreases the peak acoustic pressure increases. Additionally, if an area factor decreases to zero and becomes negative, the ray has propagated through a caustic, which contributes a phase change of 90 degrees to the wave. Thus, it is clear that the number of times that a sonic boom wave passes through a caustic should be related to the distorted boom waveform received on the ground. Examples are given based on a characterization of atmospheric turbulence due to the structure function of Tatarski as modified by Crow.

  13. Study on Atmospheric Pressure Leaching Process of Cobalt-nickel Matte%钴冰镍常压浸出工艺研究

    Institute of Scientific and Technical Information of China (English)

    周雍茂; 胡宝磊

    2012-01-01

    The cobalt-nickel matte, a reduction product from nickel converter slag by vulcanization smelting, was atmospherically pressure leached at the sulfuric acid system. The effects of sulfuric acid concentration, ratio of liquid to solid (L/S) , leaching time and temperature on leaching rate of valuable metals were investigated. The results show that L/S and sulfuric acid concentration have great influence on the leaching rate of cobalt, nickel and ferrum. The ferrum leaching rate reaches to 69%, nickel and cobalt leaching rate could be controlled below 1% and 5% respectively under the conditions including sulfuric acid concentration of 1. 6 mol/L, L/S of 5, leaching time of 2. 5 h, and leaching temperature of 85 °C. A good selectivity leaching effect was obtained.%以镍转炉渣还原硫化熔炼得到的钴冰镍为原料,在常压下于硫酸体系中进行浸出,考察了硫酸浓度、液固比、浸出时间及浸出温度对钴冰镍中有价成分浸出率的影响.结果表明,液固比和硫酸浓度对钴、镍、铁的浸出率影响较大.当硫酸浓度为1.6 mol/L、液固比5、浸出时间2.5h、浸出温度85℃时,铁浸出率达到69%,镍、钴浸出率分别控制在1%和5%以内,取得了很好的选择性浸出效果.

  14. 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.

  15. 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.

  16. High temperature bacterial leaching: HIOX project

    Energy Technology Data Exchange (ETDEWEB)

    Morin, D.; D' Hugues, P.; Bonney, C. F.; Norris, P.; Shwab, W.; Sundkvist, J-E.; Bridges, P. [Bureau de Recherhes Geologiques et Minieres, Orleans (France)

    2001-07-01

    The HIOX project was designed to investigate the use of thermophilic bacterial cultures for the leaching of chalcopyrite (CuFeS{sub 2}, the natural source of copper). Beyond bacterial leaching, the study also encompassed the downstream processing steps in an effort to develop a new method for the recovery of copper in an economical and environmentally-friendly process. Using the HIOX process copper recovery was increased to better than 90 per cent within 5 days with a 12 per cent solids culture, although some potentially limiting factors such as foam generation, nutrient concentrations and mixing/aeration efficiency were also identified. The study resulted in the establishment of a mass balance based on a simplified flowsheet of the process. Techno-economic evaluation carried out at three sites indicated technical feasibility using relatively conventional equipment and capital and operating costs in ranges that suggest that bioleaching with high temperature bacteria is an attractive alternative for the treatment of chalcopyrite concentrate. 5 tabs.

  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. 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.

  20. 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.

  1. 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.

  2. 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

  3. 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.

  4. Caustic Hydrogen Peroxide Treatment of Effluent from Cassava Processing Industry: Prospects and Limitations

    Directory of Open Access Journals (Sweden)

    Olayinka Omotosho

    2015-04-01

    Full Text Available Cassava has been described as a major part of diet in most African countries. Its processing usually requires the release of polluted effluent which has been found to be toxic, carcinogenic as well as mutagenic to some extent. In this study, the treatment process comprised of a combination of peroxide oxidation at caustic range and filtration which ensured that the key pollutant, Cyanide was converted to cyanate. Metal and other non-metal pollutants were filtered off with the aid of a graded sand filter after undergoing hydroxide formation and precipitation. Results from the study shows that an optimum dosage of 0.3mg/l was adequate for Cyanide destruction and hydroxide precipitation reactions. A comparison of the effluent from the treatment process with FEPA standards for waste water discharge shows that most of the pollutant parameters were within acceptable limits after the treatment with the exception of PO4 and BOD5. However when compared with Canadian Water Quality Guidelines for Irrigation the only parameter outstanding was the BOD5. As a result of the inadequacy of the process in handling the phosphate and biological load content of the wastewater, It is proposed that an additional treatment method such as sorption using activated carbon or use of a combined baffle flocculation and aeration techniques will be appropriate if the water is to be discharged safely into water courses or even for irrigation purposes.

  5. Caustic Injury In Adults – A Study For 3 Year Period

    Directory of Open Access Journals (Sweden)

    Radenkova-Saeva J.

    2016-10-01

    Full Text Available The aim of the study is to present the results of a 3-year clinico-epidemiological investigation of caustic injury in adults. The study includes 43 patients with acute corrosive ingestion, hospitalized in the Toxicology Clinic, University Hospital “N. I. Pirogov”, Sofia, Bulgaria, for the period 01.01. 2010-31.12.2012. The methods used include: clinical observation and examination, clinical laboratory, imaging, and psychiatric methods and tests. 43 patients between the ages of 22 and 82 with acute corrosive ingestions have been observed. Eleven were male (25.6% and 32 female (74.4%. All ingestions were intentional. Alkaline agents were used by all of the patients. The severity of poisonings varied from moderate to extremely severe. Different complications were seen in 82% of the cases - severe bleeding, perforation, fistula or/and stricture formation. Two of the patients have undergone surgical intervention - coloesophagoplastic - and have recovered completely. The motivation in different age groups was also studied. Psychiatric comorbidity occurred in patients as depressive and schizoaffective disorder, as well as existential crises. Acute corrosive ingestions by alkaline agents cause severe pathology. The severity and complex character of the injuries require good coordination between different medical specialists.

  6. 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.

  7. 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.)

  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. 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

  10. 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....

  11. METALS LEACHING FROM A MINERAL PROCESSING WASTE: A COLUMN STUDY

    Science.gov (United States)

    A mineral processing waste was used to study the effect of liquid to solid ratio (L/S) on the leaching behavior of metals. Leaching tests in the form of column and batch studies were carried out to investigate liquid to solid ratios ranging from 0.7 to 50. Although the waste pass...

  12. Aqueous leaching of polycyclic aromatic hydrocarbons from bitumen and asphalt.

    Science.gov (United States)

    Brandt, H C; de Groot, P C

    2001-12-01

    The application of bitumen in, e.g. asphalt roads, roofs and hydraulic applications will lead to the leaching of compounds from the bitumen/asphalt into the environment. Because polycyclic aromatic hydrocarbons (PAHs) are present in bitumen, static and dynamic leach tests have been performed to study the leaching behaviour of this class of compounds. Nine petroleum bitumens covering a representative range of commercially available products and one asphalt made from one of the bitumens have been tested in a static leach test. The asphalt has been also subjected to a dynamic leach test. The main conclusions are that a 30h dynamic leach test is sufficient to determine the equilibrium concentration that will be reached after bitumen or asphalt has been in contact with the water for more than 3-6 days. As an alternative to performing a leach test, this concentration can be calculated from the PAH concentrations in the bitumen, and their distribution coefficients, as calculated here, or from their aqueous solubilities. The equilibrium PAH concentrations in the leach water from bitumens stay well below the surface water limits that exist in several EEC-countries and are also more than an order of magnitude lower than the current EEC limits for potable water.

  13. 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.

  14. 氯盐型融雪剂碳钢腐蚀性的测定新方法%Determination for Chloride Salt -Type of Deicing Salt Carbon Steel Causticity

    Institute of Scientific and Technical Information of China (English)

    王树轩; 李宁; 李波; 李玉龙

    2012-01-01

    文章考虑了融雪剂使用过程的通气状态,提出测定氯盐型融雪剂碳钢腐蚀率的新方法—充氧测定法.并比较了充氧与非充氧条件下,NaCl、MgCl2和CaCl2三种融雪剂对碳钢的腐蚀性.在充氧条件下,141 h三种融雪剂的失重率相差不大,普遍大于非充氧状态下553 h的失重率,553 h时,当浓度低于4%,失重率CaCl2> MgCl2> NaCl,浓度大于4%时,失重率NaCl> CaCl2> MgCl2.并利用灰色系统理论建模,预测分析CaCl2对碳钢腐蚀性.在553 h时,非充氧条件下,灰色预测效果好,误差<±10.%In this paper, after considering the aeration state of using deicing salt, we proposed a new method of measuring for chloride salt - type of deicing salt carbon steel causticity by oxygenizing mensuration. And compare with the condition of oxygenation and dis - oxygenation. The causticity for carbon steel from the three kind of deicing salt were NaCl, MgCl2 and CaCl2- In general , the rate of weight loss of these kind of deicing salt have less difference in the condition of oxygenation with 141 h, greater than the condition of dis - oxygenation with 553 h. When the time is 553 h and the conch is lower than 4% , the rate of weight loss is: CaCl2 > MgCl2 > NaCl; and when the conch is higher than 4% , the rate of weight loss is: NaCl > CaCl, > MgCl2. We predicted and analyzed the carbon steel causticity from CaCl2 with Grey system theory model. In the condition of dis - oxygenation with 553 h, the impact of grey predicting is very good, and the inaccuracy is lower than ± 10.

  15. [Soil Phosphorus Forms and Leaching Risk in a Typically Agricultural Catchment of Hefei Suburban].

    Science.gov (United States)

    Fan, Hui-hui; Li, Ru-zhong; Pei, Ting-ting; Zhang, Rui-gang

    2016-01-15

    To investigate the soil phosphorus forms and leaching risk in a typically agricultural catchment of Ershibu River in Hefei Suburban, Chaohu Lake basin, 132 surface soil samples were collected from the catchment area. The spatial distribution of total phosphorus (TP) and bio-available phosphorus (Bio-P), and the spatial variability of soil available phosphorus (Olsen-P) and easy desorption phosphorus (CaCl2-P) were analyzed using the Kriging technology of AreGIS after speciation analysis of soil phosphorus. Moreover, the enrichment level of soil phosphorus was studied, and the phosphorus leaching risk was evaluated through determining the leaching threshold value of soil phosphorus. The results showed that the samples with high contents of TP and Bio-P mainly located in the upstream of the left tributary and on the right side of local area where two tributaries converged. The enrichment rates of soil phosphorus forms were arranged as follows: Ca-P (15.01) > OP (4.16) > TP (3. 42) > IP (2.94) > Ex-P (2.76) > Fe/Al-P (2.43) > Olsen-P (2.34). The critical value of Olsen-P leaching was 18.388 mg x kg(-1), and the leaching samples with values higher than the threshold value accounted for 16.6% of total samples. Generally, the high-risk areas mainly occurred in the upstream of the left tributary, the middle of the right tributary and the local area of the downstream of the area where two tributaries converged.

  16. Impacts of Future Land-Use Change on Nitrogen Leaching and Global Water Quality

    Science.gov (United States)

    Meiyappan, P.; Barman, R.; Jain, A. K.; McIsaac, G.; Lawrence, P.

    2011-12-01

    Agricultural expansion, excessive application of fertilizers, and increase in fossil fuel burning have led to widespread increases in anthropogenic production of reactive nitrogen (N), increasing N-deposition rates. An important consequence of these processes is intensification of soil nutrient leaching activities, leading to serious ground water and coastal water contamination problems. During the 21st century, projected land-use changes due to expansion of cropland surface are likely to significantly enhance anthropogenic soil N loading, intensifying nutrient leaching activities. Additionally, projected soil warming and increased fire disturbances in the high latitude forest ecosystems is also likely to increasingly mobilize soil N, and significantly contributing to the global leaching budget. In this study we employ a land surface model, the Integrated Science Assessment Model (ISAM), recently coupled to the NCAR Community Earth System Model (CESM1), to investigate the 21st century budget of soil N-leaching due to both anthropogenic and natural causes. ISAM (spatial resolution of 0.5ox0.5o) contains process based representation of prognostically coupled carbon-nitrogen cycles, and simulates all major N processes (immobilization, mineralization, nitrification, denitrification, leaching, biological fixation, and vegetation uptake). Biogeophysical schemes in the ISAM have been adapted from the NCAR Community Land Model (CLM3.5/CLM4) and the Common Land Model (CoLM), and fluxes of water and carbon are integrated at a time step of 30 minutes. ISAM incorporates land use change and secondary forest dynamics, to simulate the anthropogenic perturbation effects to the N cycle including atmospheric deposition and fertilizer application. Finally, the ISAM-CESM framework integrates a nutrient runoff tracer into the existing River Transport Model (RTM) in the CESM, enabling this study. In this talk, we will specifically focus on the results of a series of simulation

  17. SULPHUR DIOXIDE LEACHING OF URANIUM CONTAINING MATERIAL

    Science.gov (United States)

    Thunaes, A.; Rabbits, F.T.; Hester, K.D.; Smith, H.W.

    1958-12-01

    A process is described for extracting uranlum from uranium containing material, such as a low grade pitchblende ore, or mill taillngs, where at least part of the uraniunn is in the +4 oxidation state. After comminuting and magnetically removing any entrained lron particles the general material is made up as an aqueous slurry containing added ferric and manganese salts and treated with sulfur dioxide and aeration to an extent sufficient to form a proportion of oxysulfur acids to give a pH of about 1 to 2 but insufficient to cause excessive removal of the sulfur dioxide gas. After separating from the solids, the leach solution is adjusted to a pH of about 1.25, then treated with metallic iron in the presence of a precipitant such as a soluble phosphate, arsonate, or fluoride.

  18. 一种LEACH协议的改进算法LEACH_EH%An improved algorithm of LEACH protocol LEACH-EH

    Institute of Scientific and Technical Information of China (English)

    徐鹏

    2014-01-01

    根据 LEACH 协议的特点和局限性对其进行了改进,提出了一种 LEACH_EH ( LEACH EAHANCE )算法。它使用 K_MEANS 算法对簇进行一次性分簇,之后结合节点到簇内质心距离与节点自身剩余能量选举出簇头。它将簇形成的顺序由先簇头后成簇变为先成簇后簇头,形成一次分簇多次选举簇头的模式。通过 MATLAB 进行仿真,实验结果表明,改进后的算法比原来的协议在节点能量均衡方面有了较大的提升,延长了网络生存周期。%This paper propose a LEACH_EH algorithm based on the characteristics and limitations of the LEACH protocol.It uses the K_MEANS algorithm to cluster only once, and then elects the cluster heads by considersing the distance from node to cluster center and the node′s residual energy. It makes the order from electing cluster first and clustering second to clustering first and electing cluster second. It forms the formation of clustering only once and electing cluster multi-times. The MATLAB simulation shows that comparing with LEACH, the LEACH_ED algorithm has a great improvement in the energy balance of the node,and prolong the network life cycle abviously.

  19. 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.

  20. Performance of NiB inhibitor for PbSCC of alloy 600 in Pb-contaminated water and caustic solutions

    Science.gov (United States)

    Kim, Joung Soo; Yi, Yong-Sun; Kwon, Oh Chul; Kim, Mi-Ae; Kim, Hong Pyo

    2008-06-01

    Nickel-based iron-chromium alloys are used as steam generator (SG) tubing materials in nuclear power plants (NPPs) but experience intergranular stress corrosion cracking (IGSCC) and lead stress corrosion cracking (PbSCC) due to the harsh operating conditions of NPPs. In order to improve the integrity of SGs, many studies have sought suitable inhibitors for IGSCC, while those for PbSCC have been sought to a limited extent. In this study, the performance of nickel boride (NiB) as an inhibitor for PbSCC was evaluated. Nickel boride has been shown to be a good inhibitor for IGSCC of Alloy (or Inconel) 600 in a caustic aqueous solution containing no lead (Pb). No significant SCC was observed to occur in Alloy 600 tested in pure water under the slow strain rate test (SSRT) condition in this study. A mixed mode of IGSCC and TGSCC, however, occurred relatively easily in Alloy 600 tested in pure water containing lead oxide (PbO) at 315 °C. The susceptibility of Alloy 600 to SCC decreased with the addition of NiB, implying that NiB can be used as an inhibitor for PbSCC in Pb-contaminated water.

  1. Study on Sulfuric Acid Reduction Leaching on Copper-Cobalt Ore%某铜钴矿的硫酸还原浸出研究

    Institute of Scientific and Technical Information of China (English)

    刘大学; 王云; 袁朝新; 郭持皓; 李云; 孙聪

    2013-01-01

    The sulfuric acid reduction leaching on copper-cobalt ore of Congo (DRC) was investigated.The results show that the leaching rate of copper and cobalt reaches 93.35 % and 90.13% respectively under the following conditions including ore particle size of sample of 90%-0.074 mm,terminal pH value of 1.5,dosage of SO2 of 1.5 times of theoretical amount,reaction temperature of 80 ℃,reaction time of 120min,and ratio of liquid to solid of 4 ∶ 1.Based on the above results,the column leaching test to simulate heap leaching is conducted.The multistage leaching process is adopted to leach copper firstly and then reduction leach cobalt by column leaching process.The leaching rate of copper and cobalt reaches 72% and 66 % respectively.%研究了刚果(金)某铜钴矿的硫酸还原浸出.结果表明,在矿样粒度为-0.074 mm占90%、终点pH为1.5、SO2用量为理论量的1.5倍(4 kg/t)、浸出温度80℃、浸出时间120 min、液固比4∶1的条件下,铜、钴浸出率分别达到了93.35%和90.13%.在此基础上进行了模拟堆浸的柱浸试验,柱浸采用先浸铜再还原浸钴的分步浸出方式,铜浸出率达72%,钴浸出率为66%.

  2. Atmospheric leaching of nickel and cobalt from nickel saprolite ores using the Starved Acid Leaching Technology

    Science.gov (United States)

    Dreisinger, David

    2017-01-01

    There is great potential to recover nickel from below cut-off grade nickel saprolite ores using the Starved Acid Leach Technology (SALT). Nickel saprolite ores are normally mined as feed to Fe-Ni smelters or Ni matte smelting operations. The smelting processes typically require high Ni cut-off grades of 1.5 to 2.2% Ni, depending on the operation. These very high cutoff grades result in a significant portion of the saprolite profile being regarded as "waste" and hence having little to no value. The below cut-off grade (waste) material can be processed by atmospheric acid leaching with "starvation" levels of acid addition. The leached nickel and cobalt may be recovered as a mixed hydroxide (or alternate product). The mixed hydroxide may be added to the saprolite smelting operation feed system to increase the nickel production of the smelter or may be refined separately. The technical development of the SALT process will be described along with an economic summary. The SALT process has great potential to treat many Indonesian Nickel ores that are too low a grade for current technology.

  3. Porosity and Permeability of Round Top Mountain Rhyolite (Texas, USA Favor Coarse Crush Size for Rare Earth Element Heap Leach

    Directory of Open Access Journals (Sweden)

    Lorraine Negron

    2016-02-01

    Full Text Available Water-saturation porosity and dye-penetration permeability measurements of Round Top Mountain rhyolite confirm that a ½-inch (13-mm crush size would permit efficient acid heap leaching of yttrium and heavy rare earth elements (YHREEs hosted in yttrofluorite, a YHREE-substituted variety of fluorite. Laboratory acid leaching has extracted up to 90% of the YHREEs. The bulk insoluble gangue mineralogy of the rhyolite, 90% to 95% quartz and feldspars, assures low acid consumption. Different crush sizes were weighed, soaked in water, and reweighed over time to determine water-penetration estimated porosity. Typical porosities were 1% to 2% for gray and 3% to 8% for pink varieties of Round Top rhyolite. The same samples were re-tested after soaking in dilute sulfuric to simulate heap leaching effects. Post-leach porosity favorably increased 15% in pink and 50% in gray varieties, due to internal mineral dissolution. Next, drops of water-based writing ink were placed on rhyolite slabs up to ~10 mm thick, and monitored over time for visual dye breakthrough to the lower side. Ink penetration through 0.5 to 2.5-mm-thick slabs was rapid, with breakthrough in minutes to a few hours. Pink rhyolite breakthrough was faster than gray. Thicker slabs, 4 to 10 mm, took hours to three days for breakthrough. Porosity and permeability of the Round Top rhyolite and acid solubility of the yttrofluorite host should permit liberation of YHREEs from the bulk rock by inexpensive heap leaching at a coarse and inexpensive nominal ½-inch (13-mm crush size. The rate-limiting step in heap leach extraction would be diffusion of acid into, and back-diffusion of dissolution products out of, the crushed particles. The exceptional porosity and permeability that we document at Round Top suggest that there may be other crystalline rock deposits that economically can be exploited by a coarse-crush bulk heap leach approach.

  4. Field-scale evaluation of water fluxes and manure solution leaching in feedlot pen soils.

    Science.gov (United States)

    García, Ana R; Maisonnave, Roberto; Massobrio, Marcelo J; Fabrizio de Iorio, Alicia R

    2012-01-01

    Accumulation of beef cattle manure on feedlot pen surfaces generates large amounts of dissolved solutes that can be mobilized by water fluxes, affecting surface and groundwater quality. Our objective was to examine the long-term impacts of a beef cattle feeding operation on water fluxes and manure leaching in feedlot pens located on sandy loam soils of the subhumid Sandy Pampa region in Argentina. Bulk density, gravimetric moisture content, and chloride concentration were quantified. Rain simulation trials were performed to estimate infiltration and runoff rates. Using chloride ion as a tracer, profile analysis techniques were applied to estimate the soil moisture flux and manure conservative chemical components leaching rates. An organic stratum was found over the surface of the pen soil, separated from the underlying soil by a highly compacted thin layer (the manure-soil interface). The soil beneath the organic layer showed greater bulk density in the A horizon than in the control soil and had greater moisture content. Greater concentrations of chloride were found as a consequence of the partial sealing of the manure-soil interface. Surface runoff was the dominant process in the feedlot pen soil, whereas infiltration was the main process in control soil. Soil moisture flux beneath pens decreased substantially after 15 yr of activity. The estimated minimum leaching rate of chloride was 13 times faster than the estimated soil moisture flux. This difference suggests that chloride ions are not exclusively transported by advective flow under our conditions but also by solute diffusion and preferential flow.

  5. Influences of clinoptilolite and surfactant-modified clinoptilolite zeolite on nitrate leaching and plant growth.

    Science.gov (United States)

    Malekian, Raheleh; Abedi-Koupai, Jahangir; Eslamian, Sayed Saeid

    2011-01-30

    The increasing demands for environmental protection and sustainable food production require an increase in the use of natural and non-toxic materials for agriculture. In this study, the feasibility of using surfactant-modified zeolite (SMZ) in comparison with zeolite clinoptilolite (Cp) application to reduce nitrate leaching and enhance crop growth was investigated. The effects of size (millimeter and nanometer) and application rate (20 g kg(-1) and 60 g kg(-1)) of Cp and SMZ on nitrate leaching and crop response were also evaluated. Using soil lysimeters, it was determined that the maximum and mean nitrate concentration in the leachate of SMZ-amended soil were significantly (p<0.05) lower than those of Cp-amended soil. The amount of NO(3)-N leached from SMZ- and Cp-amended lysimeters at the higher application rate (60 g kg(-1)) was approximately 26% and 22% lower, respectively, than that from the control system. The mean grain yield, grain nitrogen content, stover dry matter, and N uptake were significantly greater in Cp-amended than SMZ-amended lysimeters. There was no significant effect due to the particle size of the two soil amendments. The results implicitly suggest that plants may have a better response if Cp is used as a fertilizer carrier rather than SMZ when applied at a rate of 60 g kg(-1).

  6. Influences of clinoptilolite and surfactant-modified clinoptilolite zeolite on nitrate leaching and plant growth

    Energy Technology Data Exchange (ETDEWEB)

    Malekian, Raheleh [Isfahan University of Technology, Isfahan, 84156-83111 (Iran, Islamic Republic of); Abedi-Koupai, Jahangir, E-mail: koupai@cc.iut.ac.ir [Isfahan University of Technology, Isfahan, 84156-83111 (Iran, Islamic Republic of); Eslamian, Sayed Saeid [Isfahan University of Technology, Isfahan, 84156-83111 (Iran, Islamic Republic of)

    2011-01-30

    The increasing demands for environmental protection and sustainable food production require an increase in the use of natural and non-toxic materials for agriculture. In this study, the feasibility of using surfactant-modified zeolite (SMZ) in comparison with zeolite clinoptilolite (Cp) application to reduce nitrate leaching and enhance crop growth was investigated. The effects of size (millimeter and nanometer) and application rate (20 g kg{sup -1} and 60 g kg{sup -1}) of Cp and SMZ on nitrate leaching and crop response were also evaluated. Using soil lysimeters, it was determined that the maximum and mean nitrate concentration in the leachate of SMZ-amended soil were significantly (p < 0.05) lower than those of Cp-amended soil. The amount of NO{sub 3}-N leached from SMZ- and Cp-amended lysimeters at the higher application rate (60 g kg{sup -1}) was approximately 26% and 22% lower, respectively, than that from the control system. The mean grain yield, grain nitrogen content, stover dry matter, and N uptake were significantly greater in Cp-amended than SMZ-amended lysimeters. There was no significant effect due to the particle size of the two soil amendments. The results implicitly suggest that plants may have a better response if Cp is used as a fertilizer carrier rather than SMZ when applied at a rate of 60 g kg{sup -1}.

  7. Nitrate leaching through climatologic water balance in a fertigated coffee plantation

    Directory of Open Access Journals (Sweden)

    Rafael Pivotto Bortolotto

    2013-12-01

    Full Text Available Nitrate losses from soil profiles by leaching should preferentially be monitored during high rainfall events and during irrigation when fertilizer nitrogen applications are elevated. Using a climatologic water balance, based on the models of Thornthwaite and Penman Monteith for potential evapotranspiration, drainage soil water fluxes below the root zone were estimated in a fertigated coffee crop. Soil solution extraction at the depth of 1 m allowed the calculation of nitrate leaching. The average nitrate concentration in soil solution for plots that received nitrogen by fertigation at a rate of 400 kg ha-1, was 5.42 mg L-1, surpassing the limit of the Brazilian legislation of 10.0 mg L-1, only during one month. For plots receiving 800 kg ha-1 of nitrogen, the average was 25.01 mg L-1, 2.5 times higher than the above-mentioned limit. This information indicates that nitrogen rates higher than 400 kg ha-1 are potentially polluting the ground water. Yearly nitrate amounts of leaching were 24.2 and 153.0 kg ha-1 for the nitrogen rates of 400 and 800 kg ha-1, respectively. The six times higher loss indicates a cost/benefit problem for coffee fertigations above 400 kg ha-1.

  8. A comparative study between the use of artificial neural networks and multiple linear regression for caustic concentration prediction in a stage of alumina production

    Directory of Open Access Journals (Sweden)

    Giovanni Leopoldo Rozza

    2015-09-01

    Full Text Available With world becoming each day a global village, enterprises continuously seek to optimize their internal processes to hold or improve their competitiveness and make better use of natural resources. In this context, decision support tools are an underlying requirement. Such tools are helpful on predicting operational issues, avoiding cost risings, loss of productivity, work-related accident leaves or environmental disasters. This paper has its focus on the prediction of spent liquor caustic concentration of Bayer process for alumina production. Caustic concentration measuring is essential to keep it at expected levels, otherwise quality issues might arise. The organization requests caustic concentration by chemical analysis laboratory once a day, such information is not enough to issue preventive actions to handle process inefficiencies that will be known only after new measurement on the next day. Thereby, this paper proposes using Multiple Linear Regression and Artificial Neural Networks techniques a mathematical model to predict the spent liquor´s caustic concentration. Hence preventive actions will occur in real time. Such models were built using software tool for numerical computation (MATLAB and a statistical analysis software package (SPSS. The models output (predicted caustic concentration were compared with the real lab data. We found evidence suggesting superior results with use of Artificial Neural Networks over Multiple Linear Regression model. The results demonstrate that replacing laboratorial analysis by the forecasting model to support technical staff on decision making could be feasible.

  9. Caustic-Side Solvent Extraction Chemical and Physical Properties Progress in FY 2000 and FY 2001.

    Energy Technology Data Exchange (ETDEWEB)

    Moyer, BA

    2002-04-17

    The purpose of this work was to provide chemical- and physical-property data addressing the technical risks of the Caustic-Side Solvent Extraction (CSSX) process as applied specifically to the removal of cesium from alkaline high-level salt waste stored at the US Department of Energy Savannah River Site. As part of the overall Salt Processing Project, this effort supported decision-making in regards to selecting a preferred technology among three alternatives: (1) CSSX, (2) nonelutable ion-exchange with an inorganic silicotitanate material and (3) precipitation with tetraphenylborate. High risks, innate to CSSX, that needed specific attention included: (1) chemical stability of the solvent matrix, (2) radiolytic stability of the solvent matrix, (3) proof-of-concept performance of the proposed process flowsheet with simulated waste, and (4) performance of the CSSX flowsheet with actual SRS high-level waste. This body of work directly addressed the chemical-stability risk and additionally provided supporting information that served to plan, carry out, and evaluate experiments conducted by other CSSX investigators addressing the other high risks. Information on cesium distribution in extraction, scrubbing, and stripping served as input for flowsheet design, provided a baseline for evaluating solvent performance under numerous stresses, and contributed to a broad understanding of the effects of expected process variables. In parallel, other measurements were directed toward learning how other system components distribute in the flowsheet. Such components include the solvent components themselves, constituents of the waste, and solvent-degradation products. Upon understanding which components influence flowsheet performance, it was then possible to address in a rational fashion how to clean up the solvent and maintain its stable function.

  10. Leachability of volatile fuel compounds from contaminated soils and the effect of plant exudates: A comparison of column and batch leaching tests.

    Science.gov (United States)

    Balseiro-Romero, María; Kidd, Petra S; Monterroso, Carmen

    2016-03-05

    Volatile fuel compounds such as fuel oxygenates (FO) (MTBE and ETBE) and BTEX (benzene, toluene, ethylbenzene and xylene) are some of the most soluble components of fuel. Characterizing the leaching potential of these compounds is essential for predicting their mobility through the soil profile and assessing the risk of groundwater contamination. Plant root exudates can play an important role in the modification of contaminant mobility in soil-plant systems, and such effects should also be considered in leaching studies. Artificially spiked samples of A and B horizons from an alumi-umbric Cambisol were leached in packed-columns and batch experiments using Milli-Q water and plant root exudates as leaching agents. The leaching potential and rate were strongly influenced by soil-contaminant interactions and by the presence of root exudates. Organic matter in A horizon preferably sorbed the most non-polar contaminants, lowering their leaching potential, and this effect was enhanced by the presence of root exudates. On the other hand, the inorganic components of the B horizon, showed a greater affinity for polar molecules, and the presence of root exudates enhanced the desorption of the contaminants. Column experiments resulted in a more realistic protocol than batch tests for predicting the leaching potential of volatile organic compounds in dissimilar soils.

  11. Comparative value of phosphate sources on the immobilization of lead, and leaching of lead and phosphorus in lead contaminated soils.

    Science.gov (United States)

    Park, Jin Hee; Bolan, Nanthi; Megharaj, Mallavarapu; Naidu, Ravi

    2011-01-15

    The mobility and bioavailability of lead (Pb) in soils can be mitigated by its immobilization using both soluble and insoluble phosphate (P) compounds. The effectiveness of insoluble P sources on Pb immobilization depends on their rate of dissolution which can be enhanced by phosphate solubilizing bacteria (PSB). In this study, the effect of soluble (potassium dihydrogen phosphate) and insoluble (rock phosphate in the presence and absence of PSB) P compounds on the immobilization of Pb, and leaching of Pb and P was examined using both naturally contaminated (SR soil: NH₄NO₃ extractable Pb: 28.7 mg/kg, pH: 5.88, organic matter: 0.7%) and Pb spiked (AH soil: NH(4)NO(3) extractable Pb: 42.7 mg/kg, pH: 5.23, organic matter: 10.9%) soils. Phosphate compounds were added at the rate of 200 mg P/kg and 800 mg P/kg for SR and AH soils, respectively. Soluble P treatment immobilized 80% and 57% of Pb in SR and AH soils, respectively. Insoluble rock phosphate immobilized 40% and 9% of Pb without PSB, and 60% and 17% with PSB in SR and AH soils, respectively. Lead leaching was the lowest when soils were amended with rock phosphate in the presence of PSB, which reduced Pb leaching by 36% for SR soil and 18% for AH soil compared to the control. The leaching of Pb increased when the soils were amended with soluble P because soluble P treatment increased dissolved organic carbon (DOC) concentration of soil, thereby increasing Pb mobility. Soluble P treatment significantly increased P leaching and 9% of total added P was leached from low P retaining AH soil. The optimum level of P amendment is a critical issue when soluble P is used as a Pb immobilizing agent because of eutrophication resulting from excessive P leaching to surface and ground water. While the soluble P compound was effective in the immobilization of Pb, it resulted in P leaching which increased with increasing levels of P addition. However, rock phosphate amendment with PSB achieved the immobilization of Pb with

  12. 内蒙古某高砷金矿石碱浸预处理-氰化浸出试验研究%Alkali Leaching Pretreatment-Cyanide Leaching Experiments on a High Arsenic Gold Ore in Inner Mongolia

    Institute of Scientific and Technical Information of China (English)

    何毅; 高柏年; 姚凯

    2016-01-01

    Gold grade of Inner Mongolia Laodonggou Gold Mine is 8.27 g/t,associated silver can be recovered,arsenic content is as high as 3.1 8%.Gold is finely disseminated and mainly exists in other minerals in inclusions form and closely symbiotic,and easily sliming.Heap leaching method was used on the on-site process while the gold leaching rate is only 50%,resource was seriously wasted.To increase the gold leaching rate,on the basis of the analysis of ore properties,alkali leaching pretreatment-all slime cyanidation leaching process at room temperature was put forward.The optimum leaching conditions de-termined are as follows:the grinding fineness of 93.5% -0.074 mm,pulp solid-liquid ratio is 1 ∶2,ad-justing the pH =1 2,alkali leaching NaOH dosage of 3 000 g/t,pretreatment for 2.5 h,leaching agent NaCN dosage of 2 000 g/t,leaching for 24 h,eventually gold and silver leaching rate were 85.49% and 80.1 2%,respectively.By heap leaching process,the gold leaching rate increased by 35 percentage points,and silver was comprehensive recovered,and the economic benefit is remarkable,can be used as the gold ore new extraction process.%内蒙古老硐沟金矿金品位波动较大,综合金品位8.27 g/t,可伴随回收银,砷含量高达3.18%。矿石中金嵌布粒度细微,主要以包裹体形态存在于其它矿物中,共生关系密切,且泥化严重。现场采用堆浸法生产,金浸出率仅50%左右,资源浪费严重。为提高金浸出率,在分析矿石性质的基础上,提出采用常温碱浸预处理—全泥氰化浸出工艺,条件试验确定的最佳浸出条件为:磨矿细度-0.074 mm 93.5%,矿浆固液比为1∶2,调节 pH =12,碱浸 NaOH 用量3000 g/t,预处理2.5 h,浸出剂 NaCN 用量为2000 g/t,浸出24 h,最终金、银浸出率分别为85.49%、80.12%。相比堆浸工艺,金浸出率提高了35个百分点以上,并综合回收了银,经济效益显著,可作为该

  13. Advances in Nitrogen Loss Leached by Precipitation from Plant Canopy

    Institute of Scientific and Technical Information of China (English)

    LI Shi-qing; JI Chun-rong; FANG Ya-ning; CHEN Xiao-li; LI Sheng-xiu

    2008-01-01

    Function of canopy in changing nutrient cycle and flux is one of the focuses in recent years. On the basis of comprehensively appraising published research, we analyzed the nitrogen loss leaching from plant canopy and several factors which affected it. We pointed out the disadvantages of the published researches and the key issues that ought to be solved: (1) The menstruation need to be advanced, and the research should be carried out on nitrogen loss leaching from the canopy of the field plant. (2) If the nitrogen is leached from the plant canopy, the research on the type of nitrogen loss should be carried out, and the nitrogen use efficiency of different varieties should be dealt on a research perspective with regard to the nitrogen leaching. (3) The research should be conducted on the mechanism and pathway, and the progress of nitrogen leaching; and the factors affecting nitrogen leaching should be included in the research, such as the leaf area of different growth stages, stomata densities, stomata conductance, and the apparent free space, which are beneficial to explain the mechanism of nitrogen leaching from the plant canopy.

  14. Thiosulfate leaching of gold from waste mobile phones.

    Science.gov (United States)

    Ha, Vinh Hung; Lee, Jae-chun; Jeong, Jinki; Hai, Huynh Trung; Jha, Manis K

    2010-06-15

    The present communication deals with the leaching of gold from the printed circuit boards (PCBs) of waste mobile phones using an effective and less hazardous system, i.e., a copper-ammonia-thiosulfate solution, as an alternative to the conventional and toxic cyanide leaching of gold. The influence of thiosulfate, ammonia and copper sulfate concentrations on the leaching of gold from PCBs of waste mobile phones was investigated. Gold extraction was found to be enhanced with solutions containing 15-20 mM cupric, 0.1-0.14 M thiosulfate, and 0.2-0.3 M ammonia. Similar trends were obtained for the leaching of gold from two different types of scraps and PCBs of waste mobile phones. From the scrap samples, 98% of the gold was leached out using a solution containing 20 mM copper, 0.12 M thiosulfate and 0.2 M ammonia. Similarly, the leaching of gold from the PCBs samples was also found to be good, but it was lower than that of scrap samples in similar experimental conditions. In this case, only 90% of the gold was leached, even with a contact time of 10h. The obtained data will be useful for the development of processes for the recycling of gold from waste mobile phones.

  15. Accelerating column leaching trial on copper sulfide ore

    Institute of Scientific and Technical Information of China (English)

    WANG Hongjiang; WU Aixiang; ZHOU Xun; WANG Shaoyong; ZHANG Jie

    2008-01-01

    The main measures to accelerate leaching sulfide ore are large spraying intensity,manual oxygen supply,temperature control and acclimated bacteria.The indoor experiment accelerating sulfide ore leaching detected the temperature during leaching process,dissolvability of oxygen,bacterial concentration,Cu concentration and slag grade.At the same time,this paper also analyzed the effect of four factors,which are bacterial diversity cultivation stage,spraying intensity,air supply,and whether to control temperature,on the leaching efficiency of copper.The results indicate that the oxygen content of leach solution has a close relationship with temperature but it is rarely affected by air supply.The bacterial concentration preserves from 106 to 107 mL-1,and temperature has a great effect on the bacterial activity under the condition of proper temperature and oxygen supply,and the lack of nutrition prevents the bacterial concentration from rising in the late stage.The relationships of the copper leaching efficiency to temperature,air feed,and spraying intensity are directly proportional.The leaching efficiencies of the cultivated bacteria and acclimation bacteria are 1.2 and 1.4 times as large as that of the original bacteria.

  16. Acidic leaching of copper and tin from used consumer equipment

    Directory of Open Access Journals (Sweden)

    Orac D.

    2015-01-01

    Full Text Available This work is focused on studying thermal pretreatment and leaching of copper and tin from printed circuit boards (PCBs from used consumer equipment. Thermal treatment experiments were realized with and without presence of oxygen at 300°C, 500°C, 700°C and 900°C for 30 minutes. Leaching experiments were performed at 80°C in 2M HCl in two stages. The first stage consisted of classic leaching experiments of samples without and after thermal treatment. The second stage consisted of oxidative leaching experiments (blowing of air or oxygen with the aim to intensify metals leaching. The results of thermal treatment experiments show that maximal mass loss after burning (combustion was 53 % (700°C and after pyrolysis 47 % (900 %. Oxidative leaching resulted in complete dissolution of copper and tin after 60. or 90 minutes of thermally treated samples. Pyrolysis and combustion have positive effects on metals dissolution in comparison with samples without thermal pretreatment. Moreover, the dissolution of metals is more effective and needs shorter leaching time.

  17. Leaching of plasticizers from polyvinylchloride perfusion lines by different lipid emulsions for premature infants under clinical conditions.

    Science.gov (United States)

    Faessler, David; McCombie, Gregor; Biedermann, Maurus; Felder, Florian; Subotic, Ulrike

    2017-03-30

    Plasticizers migrate from polyvinylchloride (PVC) infusion systems into lipid emulsions. The aim of this study was to investigate the leaching of different plasticizers from PVC perfusion lines by a selection of lipid emulsions under clinical conditions. Seven PVC perfusion lines with an equal length of 150cm and three internal diameters were perfused with three lipid emulsions: Intralipid(®) 20%, ClinOleic(®) 20% and SMOFlipid(®) 20%, mimicking clinical conditions. The concentrations of the plasticizers were measured directly in the emulsions by gas chromatography - mass spectrometry. Of the four plasticizers examined in this study, di (2-ethylhexyl) phthalate (DEHP) leached the most and was found, on average, at 46.5μg/ml in the emulsions - around one order of magnitude higher than the other plasticizers. This study demonstrates that the leaching of DEHP by lipid emulsions in conditions of total parenteral nutrition is many times higher than should be accepted and higher when compared to the other plasticizers. There was no significant difference in leaching of plasticizers in relation to the type of lipid emulsion. The influence of tube diameter on the leaching rate of plasticizers should be taken into account especially in particular exposed patients.

  18. Leaching kinetics of low grade zinc oxide ore in NH3-NH4Cl-H2O system

    Institute of Scientific and Technical Information of China (English)

    WANG Rui-xiang; TANG Mo-tang; YANG Sheng-hai; ZHAGN Wen-hai; TANG Chao-bo; HE Jing; YANG Jian-guang

    2008-01-01

    The leaching kinetics of low grade zinc oxide ore in NH3-NH4Cl-H2O system was studied. The effects of ore particle size,reaction temperature and the sum concentration of ammonium ion and ammonia on the leaching efficiency of zinc were examined.The leaching kinetics of low-grade zinc oxide ore in NH3-NH4Cl-H2O system follows the kinetic law of shrinking-core model. The results show that diffusion through the inert particle pores is the leaching kinetics rate controlling step. The calculated apparent activation energy of the process is about 7.057kJ/mol. The leaching efficiency of zinc is 92.1% under the conditions of ore particle size of 69μm, holding at 80℃ for 60min, sum ammonia concentration of 7.5mol/L, the molar ratio of ammonium to ammonia being 2:1, and the ratio (g/mL) of solid to liquid being 1:10.

  19. Pesticide leaching FOCUS scenarios if only dissolved pesticides degrade: re-assessing the importance of soil water flow

    Science.gov (United States)

    Te Brake, B.; van der Zee, S. E. A. T. M.; Verhoef, A.

    2009-04-01

    Although the pesticide screening policies assume that both dissolved and adsorbed pesticides are subject to transformation (or degradation), it is debatable whether this assumption is correct. Instead, it has been proposed that only dissolved pesticides may degrade, in line with the consensus on other organic contaminants for which only the dissolved or easily accessible fractions are biodegradable. If only dissolved pesticide fractions can degrade, this has major impacts on the pesticide risk assessment in the EU, which so far assumes all pesticide can degrade, whatever their chemical forms. In particular, if only dissolved pesticide degrades, the sorption process becomes completely irrelevant for the long term leached fraction: both regarding its (non)equilibrium and its (non)linearity assumptions. If sorption as such becomes less important, other processes should become more important for the leached fraction, and water flow as the major driving force is a logical candidate. Indeed, the rate of leaching can be shown to depend significantly on the net precipitation, with some prominent adjustments, if sorption becomes less dominant than in the current pesticide screening approaches. It will be shown that the celerity of leaching depends differently on the water flow, than does the leached fraction (which is crucial for pesticide admission policies). Therefore, a reconsideration of EU pesticide screening and admission policies may be necessary.

  20. Extended Leach Testing of Simulated LAW Cast Stone Monoliths

    Energy Technology Data Exchange (ETDEWEB)

    Serne, R. Jeffrey [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Westsik, Joseph H. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Williams, Benjamin D. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Jung, H. B. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Wang, Guohui [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

    2015-07-09

    This report describes the results from long-term laboratory leach tests performed at Pacific Northwest National Laboratory (PNNL) for Washington River Protection Solutions (WRPS) to evaluate the release of key constituents from monoliths of Cast Stone prepared with four simulated low-activity waste (LAW) liquid waste streams. Specific objectives of the Cast Stone long-term leach tests described in this report focused on four activities: 1. Extending the leaching times for selected ongoing EPA-1315 tests on monoliths made with LAW simulants beyond the conventional 63-day time period up to 609 days reported herein (with some tests continuing that will be documented later) in an effort to evaluate long-term leaching properties of Cast Stone to support future performance assessment activities. 2. Starting new EPA-1315 leach tests on archived Cast Stone monoliths made with four LAW simulants using two leachants (deionized water [DIW] and simulated Hanford Integrated Disposal Facility (IDF) Site vadose zone pore water [VZP]). 3. Evaluating the impacts of varying the iodide loading (starting iodide concentrations) in one LAW simulant (7.8 M Na Hanford Tank Waste Operations Simulator (HTWOS) Average) by manufacturing new Cast Stone monoliths and repeating the EPA-1315 leach tests using DIW and the VZP leachants. 4. Evaluating the impacts of using a non-pertechnetate form of Tc that is present in some Hanford tanks. In this activity one LAW simulant (7.8 M Na HTWOS Average) was spiked with a Tc(I)-tricarbonyl gluconate species and then solidified into Cast Stone monoliths. Cured monoliths were leached using the EPA-1315 leach protocol with DIW and VZP. The leach results for the Tc-Gluconate Cast Stone monoliths were compared to Cast Stone monoliths pertechnetate.

  1. Amounts of carbon mineralised and leached as DOC during decomposition of Norway spruce needles and fine roots

    NARCIS (Netherlands)

    Hansson, K.; Berggren Kleja, D.; Kalbitz, K.; Larsson, H.

    2010-01-01

    Changes in climate or forest management practices leading to increased litter production will most likely cause increased leaching rates of dissolved organic carbon (DOC) from the O horizon. The rhizosphere is often assumed to have a large carbon flux associated with root turnover and exudation. How

  2. 离子膜法烧碱工艺改进%Process improvement of exchange membrane caustic soda production

    Institute of Scientific and Technical Information of China (English)

    许琼武

    2012-01-01

    Through addition of titanium heat exchanger, the steam condensed water recovery and utilization, vacuum dechlorination pipe renovation measures,the ionic membrane caustic soda device stable operation. Reduces energy consumption, improves the economic benefit.%通过新增钛换热器、蒸汽冷凝水回收利用、真空脱氯氯水管改造等措施,保证了离子膜烧碱生产装置的平稳运行,降低了能耗,提高了经济效益。

  3. The mechanisms of pyrite oxidation and leaching: A fundamental perspective

    Science.gov (United States)

    Chandra, A. P.; Gerson, A. R.

    2010-09-01

    Pyrite is the earth's most abundant sulfide mineral. Its frequent undesirable association with minerals of economic value such as sphalerite, chalcopyrite and galena, and precious metals such as gold necessitates costly separation processes such as leaching and flotation. Additionally pyrite oxidation is a major contributor to the environmental problem of acid rock drainage. The surface oxidation reactions of pyrite are therefore important both economically and environmentally. Significant variations in electrical properties resulting from lattice substitution of minor and trace elements into the lattice structure exist between pyrite from different geographical locations. Furthermore the presence of low coordination surface sites as a result of conchoidal fracture causes a reduction in the band gap at the surface compared to the bulk thus adding further electrochemical variability. Given the now general acceptance after decades of research that electrochemistry dominates the oxidation process, the geographical location, elemental composition and semi-conductor type (n or p) of pyrite are important considerations. Aqueous pyrite oxidation results in the production of sulfate and ferrous iron. However other products such as elemental sulfur, polysulfides, hydrogen sulfide, ferric hydroxide, iron oxide and iron(III) oxyhydroxide may also form. Intermediate species such as thiosulfate, sulfite and polythionates are also proposed to occur. Oxidation and leach rates are generally influenced by solution Eh, pH, oxidant type and concentration, hydrodynamics, grain size and surface area in relation to solution volume, temperature and pressure. Of these, solution Eh is most critical as expected for an electrochemically controlled process, and directly correlates with surface area normalised rates. Studies using mixed mineral systems further indicate the importance of electrochemical processes during the oxidation process. Spatially resolved surface characterisation of fresh

  4. DESIGN OF AN EXPERT CONTROL SYSTEM FOR LEACHING PROCESS

    Institute of Scientific and Technical Information of China (English)

    1999-01-01

    One important step in zinc hydrometallurgy is the leaching process, which involves the dissolving of zinc-bearing material in dilute sulfuric acid to form zinc sulfate solution. The key problem in the process control is to determine the optimal pHs of the overflows of the continuous leaches and track them. An expert control system for the leaching process was designed to solve the key problem. A methodology is proposed for determining and tracking the optimal pHs with an expert control strategy based on a combination of steadystate mathematical models and rule models of the process.

  5. Studies on Leaching of Heavy Metals from E – waste

    OpenAIRE

    Caroline Michael; R.Wilfred Sugumar

    2013-01-01

    One of the global problems in the present day world is the negative impacts created by the growing e-waste on the natural resources like air, soil and water. In the present work, the discarded electronic components were allowed to leach in water samples drawn from different rivers and the leachate were analyzed for the presence of heavy metals. The results highlight that even if the contact time is short, the toxic elements tend to leach to a great extent. In our studies, Arsenic had leached ...

  6. Effect of CaF2/CaO Composite Additive on Roasting of Vanadium-Bearing Stone Coal and Acid Leaching Kinetics

    Directory of Open Access Journals (Sweden)

    Bo Wang

    2017-03-01

    Full Text Available In this paper, the composite additive of CaF2/CaO was used to extract vanadium from stone coal, and the effect of roasting and leaching kinetics were studied. The purpose of this manuscript is to realize and improve the vanadium recovery from stone coal using the composite additive. The experimental results indicated that the roasted clinker can be obtained under the conditions of CaF2/CaO at a mass ratio of 2:3 and a total additive amount of 10 wt %, a roasting temperature 850 °C, and a roasting time of 90 min. The leaching rate of vanadium can reach 86.74%, which increased by 16.4% compared with that of blank roasting under the conditions including a leaching temperature of 950 °C, a sulfuric acid concentration of 15% (v/v, a leaching time of 2 h, and a ratio of liquid to solid of 3 mL/g. The phase transformation analysis indicated that the muscovite structure was effectively destroyed during the roasting process comparing with no additives, which provided the basis for vanadium dissociation. Roasting can promote the formation of calcium vanadate, which is beneficial to the leaching of vanadium. The vanadium leaching kinetic analysis indicated that the activation energy of the acid leaching reaction decreased from 42.50 KJ/mol in the blank roasting to 22.56 KJ/mol in the calcified roasting, and the reaction order, with respect to the sulfuric acid concentration, decreased from 1.15 to 0.85. Calcified roasting has a better mineral activation than blank roasting, which can accelerate the leaching of vanadium and reduce the dependence on high-temperature and high acid levels in the leaching process.

  7. Evaluation of the leaching characteristics of wood ash and the influence of ash agglomeration

    Energy Technology Data Exchange (ETDEWEB)

    Steenari, B.-M.; Lindqvist, O. [Chalmers University of Technology, Goeteborg (Sweden); Karlsson, L.G. [Kemakta Consulting AB, Stockholm (Sweden)

    1999-11-01

    The release of mineral nutrients and other species from untreated and stabilised wood ash has been investigated. Stabilisation is applied with the aim to modify the solubility of ash components and the ash particle size, i.e. to form dense ash particle agglomerates. This process induces the formation of several secondary minerals. The most important reaction is the transformation of Ca(OH){sub 2} into CaCO{sub 3} which lowers the calcium leaching rate significantly. A significant fraction of the alkali metals, K and Na, is present in salts which are rapidly released. The short-term release of these salts, as simulated in laboratory experiments, was not reduced by the stabilisation methods applied. Generally, low leaching rates were observed for the important plant nutrients P and Mg as well as for Fe and other metals from both untreated and agglomerated ashes. Thermodynamics equilibrium modelling of the hardening process showed that in addition to the transformation of Ca(OH){sub 2} to CaCO{sub 3}, formation of the mineral ettringite is possible at a high pH. Experimental results have confirmed this. As the pH in the pore solution decreases during long-term leaching ettringite will be transformed into calcium carbonate and gypsum. In accordance with the experimental results, no formation of secondary solubility controlling potassium or sodium minerals was indicated by the modelling results. (author)

  8. Porous starch/cellulose nanofibers composite prepared by salt leaching technique for tissue engineering.

    Science.gov (United States)

    Nasri-Nasrabadi, Bijan; Mehrasa, Mohammad; Rafienia, Mohammad; Bonakdar, Shahin; Behzad, Tayebeh; Gavanji, Shahin

    2014-08-08

    Starch/cellulose nanofibers composites with proper porosity pore size, mechanical strength, and biodegradability for cartilage tissue engineering have been reported in this study. The porous thermoplastic starch-based composites were prepared by combining film casting, salt leaching, and freeze drying methods. The diameter of 70% nanofibers was in the range of 40-90 nm. All samples had interconnected porous morphology; however an increase in pore interconnectivity was observed when the sodium chloride ratio was increased in the salt leaching. Scaffolds with the total porogen content of 70 wt% exhibited adequate mechanical properties for cartilage tissue engineering applications. The water uptake ratio of nanocomposites was remarkably enhanced by adding 10% cellulose nanofibers. The scaffolds were partially destroyed due to low in vitro degradation rate after more than 20 weeks. Cultivation of isolated rabbit chondrocytes on the fabricated scaffold proved that the incorporation of nanofibers in starch structure improves cell attachment and proliferation.

  9. Nitrogen and Carbon Leaching in Repacked Sandy Soil with Added Fine Particulate Biochar

    DEFF Research Database (Denmark)

    Bruun, Esben W.; Petersen, Carsten; Strobel, Bjarne W.

    2012-01-01

    Biochar amendment to soil may affect N turnover and retention, and may cause translocation of dissolved and particulate C. We investigated effects of three fine particulate biochars made of wheat (Triticum aestivum L.) straw (one by slow pyrolysis and two by fast pyrolysis) on N and C leaching from...... repacked sandy soil columns (length: 51 cm). Biochar (2 wt%), ammonium fertilizer (NH4+, amount corresponding to 300 kg N ha-1) and an inert tracer (bromide) were added to a 3-cm top layer of sandy loam, and the columns were then irrigated with constant rate (36 mm d-1) for 15 d. The total amount...... of leachate came to about 3.0 water filled pore volumes (WFPVs). Our study revealed a high mobility of labile C components originating from the fine particulate fast pyrolysis biochar. This finding highlights a potential risk of C leaching coupled with the use of fast pyrolysis biochars for soil amendment...

  10. Effect of temperature and precipitation on nitrate leaching from organic cereal cropping systems in Denmark

    DEFF Research Database (Denmark)

    Jabloun, Mohamed; Schelde, Kirsten; Tao, F;

    2015-01-01

    management. There were significant effects on annual N concentration and NO3single bondN leaching of location, rotation, previous crop and crop cover during autumn and winter. The relative effects of temperature and precipitation differed between seasons and cropping systems. A sensitivity analysis revealed......The effect of variation in seasonal temperature and precipitation on soil water nitrate (NO3single bondN) concentration and leaching from winter and spring cereals cropping systems was investigated over three consecutive four-year crop rotation cycles from 1997 to 2008 in an organic farming crop...... rotation experiment in Denmark. Three experimental sites, varying in climate and soil type from coarse sand to sandy loam, were investigated. The experiment included experimental treatments with different rotations, manure rate and cover crop, and soil nitrate concentrations was monitored using suction...

  11. Modeling of Nitrate Leaching from a Potato Field using HYDRUS-2D

    DEFF Research Database (Denmark)

    Shekofteh, Hosein; Afyuni, Majid; Hajabbasi, Mohammad Ali;

    2013-01-01

    Excessive use of nitrogen (N) fertilizers is likely to be responsible for the increasing nitrate in groundwater. Thus, appropriate water and nutrient management is required to minimize groundwater pollution and to maximize the nutrient-use efficiency. In this study HYDRUS-2D software package...... was applied to simulate nitrate leaching from a drip-irrigated sandy agricultural soil for varying emitter discharges and various amounts of fertilizer. It was found that for small emitter discharge values free drainage increased significantly with increase in discharge, whereas the increase was leveled out...... at greater discharge values. Nitrate leaching increased with an increase in emitter discharge and amount of fertilizer, but the rate of increase was most significant for low emitter discharges. Based on the results, with regard to the selection of emitter discharge and the amount of appropriate fertilizer...

  12. Cross-Comparison of Leaching Strains Isolated from Two Different Regions: Chambishi and Dexing Copper Mines

    Directory of Open Access Journals (Sweden)

    Baba Ngom

    2014-01-01

    Full Text Available A cross-comparison of six strains isolated from two different regions, Chambishi copper mine (Zambia, Africa and Dexing copper mine (China, Asia, was conducted to study the leaching efficiency of low grade copper ores. The strains belong to the three major species often encountered in bioleaching of copper sulfide ores under mesophilic conditions: Acidithiobacillus ferrooxidans, Acidithiobacillus thiooxidans, and Leptospirillum ferriphilum. Prior to their study in bioleaching, the different strains were characterized and compared at physiological level. The results revealed that, except for copper tolerance, strains within species presented almost similar physiological traits with slight advantages of Chambishi strains. However, in terms of leaching efficiency, native strains always achieved higher cell density and greater iron and copper extraction rates than the foreign microorganisms. In addition, microbial community analysis revealed that the different mixed cultures shared almost the same profile, and At. ferrooxidans strains always outcompeted the other strains.

  13. Cross-comparison of leaching strains isolated from two different regions: Chambishi and Dexing copper mines.

    Science.gov (United States)

    Ngom, Baba; Liang, Yili; Liu, Xueduan

    2014-01-01

    A cross-comparison of six strains isolated from two different regions, Chambishi copper mine (Zambia, Africa) and Dexing copper mine (China, Asia), was conducted to study the leaching efficiency of low grade copper ores. The strains belong to the three major species often encountered in bioleaching of copper sulfide ores under mesophilic conditions: Acidithiobacillus ferrooxidans, Acidithiobacillus thiooxidans, and Leptospirillum ferriphilum. Prior to their study in bioleaching, the different strains were characterized and compared at physiological level. The results revealed that, except for copper tolerance, strains within species presented almost similar physiological traits with slight advantages of Chambishi strains. However, in terms of leaching efficiency, native strains always achieved higher cell density and greater iron and copper extraction rates than the foreign microorganisms. In addition, microbial community analysis revealed that the different mixed cultures shared almost the same profile, and At. ferrooxidans strains always outcompeted the other strains.

  14. Leaching behaviour of and Cs disposition in a UMo powellite glass–ceramic

    Energy Technology Data Exchange (ETDEWEB)

    Vance, E.R., E-mail: erv@ansto.gov.au [Institute of Materials Engineering, ANSTO, Kirrawee DC, NSW 2232 (Australia); Davis, J.; Olufson, K.; Gregg, D.J.; Blackford, M.G.; Griffiths, G.R. [Institute of Materials Engineering, ANSTO, Kirrawee DC, NSW 2232 (Australia); Farnan, I. [Department of Earth Sciences, University of Cambridge, Cambridge CB2 3EQ (United Kingdom); Sullivan, J.; Sprouster, D.; Campbell, C.; Hughes, J. [Centre for Antimatter-Matter Studies (CAMS), Research School of Physics and Engineering, Australian National University, Canberra, ACT 0200 (Australia)

    2014-05-01

    A UMo powellite glass–ceramic designed by French workers to immobilise Mo-rich intermediate-level waste was found to be quite leach resistant in water at 90 °C with the dissolution of Cs, Mo, Na, B and Ca not exceeding 2 g/L in normalised PCT tests. {sup 133}Cs solid state nuclear magnetic resonance and scanning electron microscopy (SEM) showed the Cs to inhabit the glass phase. The microstructures were not greatly affected by cooling rates between 1 and 5 °C/min or by introducing 10 times as much Cs and Sr. Protracted leach tests at 90 °C showed surface alteration as evidenced by SEM and particularly transmission electron microscopy; the main alteration phase was a Zn aluminosilicate but several other alteration phases were evident. Voidage in the alteration layers was indicated from enhanced lifetimes in positron annihilation lifetime spectroscopy.

  15. Effects of Pregnant Leach Solution Temperature on the Permeability of Gravelly Drainage Layer of Heap Leaching Structures

    Directory of Open Access Journals (Sweden)

    mehdi amini

    2013-12-01

    Full Text Available In copper heap leaching structures, the ore is leached by an acidic solution. After dissolving the ore mineral, the heap is drained off in the acidic solution using a drainage system (consisting of a network of perforated polyethylene pipes and gravelly drainage layers and is, then, transferred to the leaching plant for copper extraction where the copper is extracted and the remaining solution is dripped over the ore heap for re-leaching. In this process, the reaction between the acidic solution and copper oxide ore is exothermal and the pregnant leach solution (PLS, which is drained off the leaching heap, has a higher temperature than the dripped acidic solution. The PLS temperature variations cause some changes in the viscosity and density which affect the gravelly drainage layer's permeability. In this research, a special permeability measuring system was devised for determining the effects of the PLS temperature variations on the permeability coefficient of the gravelly drainage layer of heap leaching structures. The system, consisting of a thermal acid resistant element and a thermocouple, controls the PLS temperature, which helps measure the permeability coefficient of the gravelly drainage layer. The PLS and gravelly drainage layer of Sarcheshmeh copper mine heap leaching structure No. 1 were used in this study. The permeability coefficient of the gravelly soil was measured against the PLS and pure water at temperatures varying between 3°C to 60°C. Also, the viscosity and density of the PLS and pure water were measured at these temperatures and, using existing theoretical relations, the permeability coefficient of the gravel was computed. A comparison between the experimental and theoretical results revealed a good conformity between the two sets of results. Finally, a case (Taft heap leaching structure, Yazd, Iran was studied and its gravelly drainage layer was designed based on the results of the present research.

  16. 高效生物处理技术在碱渣处理装置的工业应用%Commercial application of new high-efficiency biological treatment technology in caustic sludge treatment

    Institute of Scientific and Technical Information of China (English)

    高瑞民; 张书勤; 黄勇; 周东彦

    2012-01-01

    The process principles and technical features of the conventional caustic sludge treatment and high-efficient biological treatment technologies are studied and compared. The high-efficiency biological treatment technology uses MERION partial oxidation and neutralization extraction process to oxidize sulfides into thiosulfate to separate sulfide in the form of gaseous state so as to recover phenol and oil from caustic sludge. With the principles of biological metabolism oxidation, the organisms and sulfides in sewage are oxidized and decomposed into CO2, H2O and sulfate respectively. Through microbial decomposition, oxidation and conversion, VOC, H2O and exhaust gas are oxidized and decomposed into C02, H2O, NO32- , SO4 2-etc to remove other chemical substances, like alcohol, aldehyde and acetic acid to complete the harmless treatment. The technology is high in removal rate of harmful substances like COD, sulfide and phenol in caustic sludge ( >99%). The stable water quality (100% on specification) meets the standard of cooling water. The annual saving of water is 600 dam3, and the annual saving of cost for treatment to meet environmental protection is 10 million Yuan RMB.%分析对比传统碱渣处理和高效生物处理技术的工艺原理和技术特点.高效生物处理技术采用MERI-CON部分氧化和中和萃取工艺,将硫化物氧化成硫代硫酸盐,使硫化物以气态形式分离,回收碱渣中的酚和油;利用生物代谢氧化原理,将污水中有机物氧化分解成CO2和H2O,使硫化物转化成硫酸盐;利用微生物的分解、氧化和转化功能,将VOC,H2S和废气氧化分解成CO2,H2O,NO32-,SO42-等,去除醇、醛和酸等化学物质,完成无害化处理.该技术对碱渣中COD、硫化物和挥发酚等去除率高(>99%),处理后水质稳定(合格率100%),达到循环冷却用水要求,年节省用水600 dam3,累计节约环保处理费用1 000×104 RMB¥.

  17. Effect of low dose electron beam irradiation on the alteration layer formed during nuclear glass leaching

    Science.gov (United States)

    Mougnaud, S.; Tribet, M.; Renault, J.-P.; Jollivet, P.; Panczer, G.; Charpentier, T.; Jégou, C.

    2016-12-01

    This investigation concerns borosilicate glass leaching mechanisms and the evolution of alteration layer under electron beam irradiation. A simple glass doped with rare earth elements was selected in order to access mechanistic and structural information and better evaluate the effects of irradiation. It was fully leached in initially pure water at 90 °C and at high glass surface area to solution volume ratio (S/V = 20 000 m-1) in static conditions. Under these conditions, the system quickly reaches the residual alteration rate regime. A small particle size fraction (2-5 μm) was sampled in order to obtain a fairly homogeneous altered material enabling the use of bulk characterization methods. External irradiations with 10 MeV electrons up to a dose of 10 MGy were performed either before or after leaching, to investigate respectively the effect of initial glass irradiation on its alteration behavior and the irradiation stability of the alteration layer. Glass dissolution rate was analyzed by regular leachate samplings and the alteration layer structure was characterized by Raman, luminescence (continuous or time-resolved), and 29Si MAS NMR and EPR spectroscopy. It was shown that the small initial glass evolutions under irradiation did not induce any modification of the leaching kinetic nor of the structure of the alteration layer. The alteration process seemed to "smooth over" the created defects. Otherwise, the alteration layer and initial glass appeared to have different behaviors under irradiation. No Eu3+ reduction was detected in the alteration layer after irradiation and the defect creation efficiency was much lower than for initial glass. This can possibly be explained by the protective role of pore water contained in the altered material (∼20%). Moreover, a slight depolymerization of the silicon network of the altered glass under irradiation with electrons was evidenced, whereas in the initial glass it typically repolymerizes.

  18. Influence of Mechanical Activation on Acid Leaching Dephosphorization of High-phosphorus Iron Ore Concentrates

    Institute of Scientific and Technical Information of China (English)

    De-qing ZHU; Hao WANG; Jian PAN; Cong-cong YANG

    2016-01-01

    High pressure roll grinding (HPRG)and ball milling were compared to investigate the influence of me-chanical activation on the acid leaching dephosphorization of a high-phosphorus iron ore concentrate,which was man-ufactured through magnetizing roasting-magnetic separation of high-phosphorus oolitic iron ores.The results indica-ted that when high-phosphorus iron ore concentrates containing 54·92 mass% iron and 0·76 mass% phosphorus were directly processed through acid leaching,iron ore concentrates containing 55·74 mass% iron and 0·33 mass%phosphorus with an iron recovery of 84·64% and dephosphorization of 63·79% were obtained.When high-phosphor-us iron ore concentrates activated by ball milling were processed by acid leaching,iron ore concentrates containing 56·03 mass% iron and 0·21 mass% phosphorus with an iron recovery of 85·65% and dephosphorization of 77·49%were obtained.Meanwhile,when high-phosphorus iron ore concentrates activated by HPRG were processed by acid leaching,iron ore concentrates containing 58·02 mass% iron and 0·10 mass% phosphorus were obtained,with the iron recovery reaching 88·42% and the dephosphorization rate reaching 88·99%.Mechanistic studies demonstrated that ball milling can reduce the particle size,demonstrating a prominent reunion phenomenon.In contrast,HPRG pretreatment contributes to the formation of more cracks within the particles and selective dissociation of iron and P bearing minerals,which can provide the favorable kinetic conditions to accelerate the solid-liquid reaction rate.As such,the crystal structure is destroyed and the surface energy of mineral particles is strengthened by mechanical ac-tivation,further strengthening the dephosphorization.

  19. Radiotracer investigation in gold leaching tanks.

    Science.gov (United States)

    Dagadu, C P K; Akaho, E H K; Danso, K A; Stegowski, Z; Furman, L

    2012-01-01

    Measurement and analysis of residence time distribution (RTD) is a classical method to investigate performance of chemical reactors. In the present investigation, the radioactive tracer technique was used to measure the RTD of aqueous phase in a series of gold leaching tanks at the Damang gold processing plant in Ghana. The objective of the investigation was to measure the effective volume of each tank and validate the design data after recent process intensification or revamping of the plant. I-131 was used as a radioactive tracer and was instantaneously injected into the feed stream of the first tank and monitored at the outlet of different tanks. Both sampling and online measurement methods were used to monitor the tracer concentration. The results of measurements indicated that both the methods provided identical RTD curves. The mean residence time (MRT) and effective volume of each tank was estimated. The tanks-in-series model with exchange between active and stagnant volume was used and found suitable to describe the flow structure of aqueous phase in the tanks. The estimated effective volume of the tanks and high degree of mixing in tanks could validate the design data and confirmed the expectation of the plant engineer after intensification of the process.

  20. Caustic Recycle from Hanford Tank Waste Using NaSICON Ceramic Membrane Salt Splitting Process

    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.

    2009-02-20

    A family of inorganic ceramic materials, called sodium (Na) Super Ion Conductors (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 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 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.

  1. Molybdenum removal from copper ore concentrate by sodium hypochlorite leaching

    Institute of Scientific and Technical Information of China (English)

    Liu Youcai; Zhong Hong; Cao Zhanfang

    2011-01-01

    The removal of molybdenum from a copper ore concentrate by sodium hypochlorite leaching was investigated. The results show that leaching time, liquid to solid ratio, leaching ternperature, agitation speed, and sodium hypochlorite and sodium hydroxide concentrations all have a significant effect on the removal of molybdenum. The optimum process operating parameters were found to be: time, 4 h: sodium hydroxide concentration, 10%; sodium hypochlorite concentration, 8%; liquid to solid ratio, 10:1; temperature, 50℃; and,agitation speed, 500 r/min. Under these conditions the extraction of molybdenum is greater than 99.9% and the extraction of copper is less than 0.01%. A shrinking particle model could be used to describe the leaching process. The apparent activation energy of the dissolution reaction was found to be approximately 8.8 kJ/mol.

  2. The leaching behavior of simulated HLW glass under repository condition

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    As the multibarrier system has been adopted to dispose HLW glass in geological formation in many countries, it was important to study the leaching behavior of vitrification under geological formation. This article describes the leaching behavior of simulated high level waste glass (90Nd/10), which can incorporate 16 wt.% simulated HLW in five kinds of geological media, such as granite, cement, bentonite, Fe3O4, etc. The durable experimental results show that the glass had less mass loss in granite and more mass loss in bentonite after a two-year leaching test. The SEM/XEDS analysis shows some element distributions on the leached specimen's surface, i.e., Na, Si and Mg elements were reduced on the specimen's surface, whereas Ba, Al, and Fe were enriched on the specimen's surface.

  3. An Energy Balanced Algorithm of LEACH Protocol in WSN

    Directory of Open Access Journals (Sweden)

    Chunyao Fu

    2013-01-01

    Full Text Available In wireless sensor networks (WSNs, due to the limitation of nodes energy, energy efficiency is an important factor should be considered when the protocols are designing. As a typical representative of hierarchical routing protocols, LEACH Protocol plays an important role. In response to the uneven energy distribution that is caused by the randomness of cluster heads forming , this paper proposes a new improved algorithm of LEACH protocol (LEACH-TLCH which is intended to balance the energy consumption of the entire network and extend the life of the network . The new algorithm is emulated by Matlab simulation platform, the simulation results indicate that both energy efficiency and the lifetime of the network are better than that of LEACH Protocol.

  4. Leaching behavior of persistent organic pollutants (POPs) in shredder residues.

    Science.gov (United States)

    Sakai, S; Urano, S; Takatsuki, H

    1998-01-01

    It is well known that some kinds of waste contain persistent organic pollutants (POPs) such as PCDD/DFs and PCBs. Leaching behaviors of these chemicals, however, have not been focused so much because of their low leachability. On the other hand, shredder residues originated from automobiles and electric appliances consist mainly of plastics, such as PVC, which contain additives including DEHP. In this study, contents analyses and leaching tests with and without surfactant-like substances for shredder residues were conducted. As a result, shredder residues from automobile and electric appliance contained PCBs in ppm level and a quantity of PCDD/DFs. Surfactant-like substances increase the leaching concentration of POPs. DEHP also leached out considerably even though using distilled water.

  5. STUDY ON HIGH ACID LEACHING REACTIVE CALCINED KAOLIN

    Institute of Scientific and Technical Information of China (English)

    1999-01-01

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

  6. Leaching of Added Selenium in Soils Low in Native Selenium

    DEFF Research Database (Denmark)

    Nielsen, Gunnar Gissel; Hamdy, A. A.

    1977-01-01

    A soil column experiment was performed to evaluate the influence of organic matter and lime on the leaching and distribution of added selenite. 75Se-labeled Na2SeO3 was added to water-saturated soil columns with a diameter of 4.25 cm and a length of 16-20 cm. Leaching started immediately, one l...... water being added per column during the course of 1 wk. Most of the selenite did not move through the soil, and only a few per cent were found in the leaching water. Leaching was greatest in sandy soil. It was increased by the addition of lime, but decreased by addition of organic matter. Most...

  7. Drenagem interna e lixiviação de nitrato em um latossolo sob sucessão milho-braquiária-milho, com diferentes doses de nitrogênio Internal drainage and nitrate leaching in a typic hapludox under a maize-brachiaria-maize succession at different nitrogen fertilizer rates

    Directory of Open Access Journals (Sweden)

    Flávia Carvalho Silva Fernandes

    2009-10-01

    precipitação pluvial total (97 mm durante o primeiro cultivo de milho, de 26,1 a 58,1 % da precipitação pluvial total (695 mm no cultivo da braquiária e pousio e de 56,6 a 87,4 % do total de 419 mm de precipitação pluvial no segundo cultivo de milho. A lixiviação de NO3-total (do fertilizante e outras fontes foi muito baixa no primeiro cultivo de milho em todas as doses de N e significativa para as doses de 120 e 180 kg ha-1 nos períodos da cultura de braquiária mais pousio (26,16 kg ha-1 para a dose de 120 e 39,8 kg ha-1 para a de 180 kg ha-1 e da segunda cultura de milho (aproximadamente 23 kg ha-1 para ambas as doses. A lixiviação de NO3-proveniente do fertilizante foi praticamente nula no primeiro cultivo de milho e, em geral, baixa durante o cultivo de braquiária e o segundo cultivo de milho.The ideal N fertilization should be defined to satisfy the crop needs, but with minimum environmental risk. For this purpose, N fertilizer recommendations must be as accurate as possible. This study was carried out in a sand-clay soil (22 º 42 ' 30 '' S; 47 º 38 ' 00 '' W; 546 m asl and the objective was to evaluate the internal drainage and nitrate leaching during the cycles of three crops in succession under no-tillage at a soil depth of 0.80 m, using different doses of 15N -labeled ammonium sulphate. The crop succession consisted of: maize in 2006 followed by brachiaria plus fallow and finally maize in 2007. Labeled N fertilizer rates of 60, 120 and 180 kg ha-1 and a control (no N were tested. The labeled fertilizer was applied to previously defined subplots, only to maize in 2006. Internal drainage was derived from the soil-water flux density calculated by the Darcy-Buckingham equation in which the hydraulic conductivity and total water potential gradient were estimated based on daily readings of Hg tensiometers at depths of 0.70, 0.80 and 0.90 m. The hydraulic conductivity was determined in the field as a function of soil-water matric potential at a depth of 0

  8. MODULAR CAUSTIC SIDE SOLVENT EXTRACTION UNIT (MCU) GAMMA MONITORS SYSTEM FINAL REPORT

    Energy Technology Data Exchange (ETDEWEB)

    Casella, V

    2005-12-15

    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 Closure Business Unit (CBU) 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. Gamma-ray monitors are required to: (1) Measure the Cs-137 concentration in the decontaminated salt solution before entering the DSS (Decontaminated Salt Solution) Hold Tank, (2) Measure the Cs-137 concentration in the strip effluent before entering the Strip Effluent Hold Tank, (3) 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 fifteen times higher than the Cs-137 concentration in the Feed Tank.) Sodium iodide monitors are used to measure the Cs-137 concentration in the piping before the DSS Hold tank, while GM monitors are used for Cs-137 measurements before the Strip Effluent Hold Tank. Tungsten shields were designed using Monte Carlo calculations and fabricated to reduce the process background radiation at the detector positions. These monitors were calibrated with NIST traceable standards that were specially made to be the same as the piping being monitored. Since this gamma ray monitoring system is unique, specially designed software was written and acceptance tested by Savannah River National Laboratory personnel. The software is a LabView-based application that serves as a unified

  9. Caustic-Side Solvent-Extraction Modeling for Hanford Interim Pretreatment System

    Energy Technology Data Exchange (ETDEWEB)

    Moyer, B.A.; Birdwell, J.F.; Delmau, L. H.; McFarlane, J.

    2008-06-01

    The purpose of this work is to examine the applicability of the Caustic-Side Solvent Extraction (CSSX) process for the removal of cesium from Hanford tank-waste supernatant solutions in support of the Hanford Interim Pretreatment System (IPS). The Hanford waste types are more challenging than those at the Savannah River Site (SRS) in that they contain significantly higher levels of potassium, the chief competing ion in the extraction of cesium. It was confirmed by use of the CSSX model that the higher levels of potassium depress the cesium distribution ratio (DCs), as validated by measurement of DCs values for four of eight specified Hanford waste-simulant compositions. The model predictions were good to an apparent standard error of ±11%. It is concluded from batch distribution experiments, physical-property measurements, equilibrium modeling, flowsheet calculations, and contactor sizing that the CSSX process as currently employed for cesium removal from alkaline salt waste at the SRS is capable of treating similar Hanford tank feeds. For the most challenging waste composition, 41 stages would be required to provide a cesium decontamination factor (DF) of 5000 and a concentration factor (CF) of 5. Commercial contacting equipment with rotor diameters of 10 in. for extraction and 5 in. for stripping should have the capacity to meet throughput requirements, but testing will be required to confirm that the needed efficiency and hydraulic performance are actually obtainable. Markedly improved flowsheet performance was calculated for a new solvent formulation employing the more soluble cesium extractant BEHBCalixC6 used with alternative scrub and strip solutions, respectively 0.1 M NaOH and 10 mM boric acid. The improved system can meet minimum requirements (DF = 5000 and CF = 5) with 17 stages or more ambitious goals (DF = 40,000 and CF = 15) with 19 stages. Potential benefits of further research and development are identified that would lead to reduced costs, greater

  10. Assessment of leaching loss estimates and gross load of nitrogen from arable land in Sweden

    Energy Technology Data Exchange (ETDEWEB)

    Hoffman, Markus (Swedish Univ. of Agricultural Sciences, Uppsala (Sweden). Dept. of Soil Sciences)

    1999-01-01

    The focus of this thesis is on calculating N leaching loss estimates and gross loads of nitrogen. Calculations were done at two different scales, from field resolution in a small catchment to calculations at a large scale for the south and central part of Sweden. The latter study was initiated by Swedish commitments to international agreements concerning a decrease in N emissions to the Baltic Sea. Three of the papers deal with leaching of nitrogen in different periods: as it may have been in the 19[sup th] century, the current situation, and suggestions for a decrease with different countermeasures. The tools used in making these estimations were the SOIL/SOILN models. Calculations indicate that average N leaching was about the same in the 19[sup th] century as it is today at the end of the 20[sup th] century. The main reasons for high losses in the 19[sup th] century were high mineralisation rates in newly ploughed grassland, crop stress due to unfavourable conditions caused poor utilisation of N by crops, and large areas of bare fallow. N leaching was at its lowest in the 1930's due to larger N utilisation, a general termination of enhanced mineralisation and a large acreage of ley. Since then leaching has increased by on average about 60%, and more in the south of Sweden. Results also indicate that the draining of lakes has considerably decreased the retention capacity and is, along with the increase in gross load, one of the main causes of increased net load to the sea. A decrease in N leaching was estimated for the period 1985-1994. The decrease was mostly due to a smaller total area of arable land and an increase in the acreage of ley at the expense of cereals. The increase in the percentage of ley in the ten-year period (1985-1994) was the largest occurring in such a short time in the last 130 years in Sweden. Scenario calculations indicate that there is a potential for a decrease in the gross load of approximately 10 ktonnes from the current level of

  11. Steady-state leaching of tritiated water from silica gel

    DEFF Research Database (Denmark)

    Das, H.A.; Hou, Xiaolin

    2009-01-01

    Aqueous leaching of tritium from silica gel, loaded by absorption of water vapor, makes part of reactor de-commissioning. It is found to follow the formulation of steady-state diffusion.......Aqueous leaching of tritium from silica gel, loaded by absorption of water vapor, makes part of reactor de-commissioning. It is found to follow the formulation of steady-state diffusion....

  12. 空气氧化—氨浸出废旧电路板中的铜%Ammonia-Ammonium Sulfate Copper Leaching from Waste Printed Circuit Boards

    Institute of Scientific and Technical Information of China (English)

    张有新; 李静; 潘发芳

    2013-01-01

    A novel hydrometallurgical process of copper recovery from waste printed circuit boards was introduced. In this process, air was blown into solution as oxidant for copper leaching in NH3-(NH4)2SO4-H2O system, while leaching residue was treated by physical method. The effects of ammonia and ammonium sulfate concentration, ratio of solid to liquid, leaching temperature, air flow and leaching time on copper leaching rate were investigated. The results show that copper leaching rate is up to 96. 67% under the following optimum conditions including ammonia concentration of 2 mol/L, ammonium sulfate concentration of 2 mol/L, ratio of solid to liquid of 1 : 20, leaching temperature of 25 ℃ , air flow of 8 m3/h and leaching time of 4 h.%提出了在氨水—硫酸铵体系下鼓入空气浸出废旧电路板中铜的新工艺.考察了氨水浓度、硫酸铵浓度、固液比、反应温度、通入空气流量和浸出时间对铜浸出率的影响.结果表明,在下述最佳浸出条件下,渣计铜浸出率达到96.67%:氨水浓度2 mol/L,硫酸铵浓度2 mol/L,固液比1∶20,反应温度25℃、通入空气量8 m3/h、浸出时间4h.

  13. 废氰渣综合回收银铜试验研究%Recovery of Silver and Copper From Spent Cyanide Leaching Residue

    Institute of Scientific and Technical Information of China (English)

    杨涛; 曾斌; 余攀; 王瑞祥

    2013-01-01

    Recovery of silver and copper from cyanide leaching residue by roasting-leaching of copper using sulfuric acid-leaching of silver using cyanide was studied .The results show that the residue mixes with NaOH (the dosage of 6% ) and is roasted for 3 h at temperature of 630 ℃ .Copper is leached from the roasted product using sulfuric acid at the conditions of sulfuric acid concentration of 1 .25 mol/L ,the ratio between liquid volume and solid mass of 4 ∶ 1 ,temperature of 100 ℃ and leaching time of 4 h ,the leaching rate of copper is 97 .4% .Then using ammonium bicarbonate to adjust solution pH 9 .5-11 ,at the conditions of sodium cyanide concentration of 4‰ ,the ratio between liquid volume and solid mass of 3∶1 ,room temperature and leaching time of 36 h ,the leaching rate of silver reaches 79 .85% .%研究了从某废氰渣中综合回收有价金属银、铜。试验结果表明:废氰渣中加入6%氢氧化钠,在630℃下焙烧3 h ,然后在液固体积质量比4∶1、硫酸浓度1.25 mol/L、温度100℃、浸出时间4 h条件下浸出铜,铜浸出率为97.4%;然后在液固体积质量比3∶1、用碳酸氢铵调p H为9.5~11、氰化钠用量4‰、常温下浸出36 h ,银浸出率达79.85%。

  14. Nitrate leaching from intensive organic farms to groundwater

    Science.gov (United States)

    Dahan, O.; Babad, A.; Lazarovitch, N.; Russak, E. E.; Kurtzman, D.

    2014-01-01

    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 from both organic and conventional greenhouses.

  15. Studies on Leaching of Heavy Metals from E – waste

    Directory of Open Access Journals (Sweden)

    Caroline Michael

    2013-12-01

    Full Text Available One of the global problems in the present day world is the negative impacts created by the growing e-waste on the natural resources like air, soil and water. In the present work, the discarded electronic components were allowed to leach in water samples drawn from different rivers and the leachate were analyzed for the presence of heavy metals. The results highlight that even if the contact time is short, the toxic elements tend to leach to a great extent. In our studies, Arsenic had leached to an extent of 0.053ppm, Cadmium 0.010 ppm, Chromium 0.029 ppm, Lead 0.042ppm and Mercury 0.061ppm. The results indicate that most of the metals have a tendency to leach and the extent of leaching depends on the quality of the water. As a result of leaching the physico-chemical parameters like pH, hardness, conductance and TDS of the water samples underwent a change. On the other hand, the physical parameters like viscosity, density, were not much affected. These studies highlight the danger of dumping the discarded electronic components in river beds especially when the water flow is less and when the water is stagnated.

  16. Leaching of metals from cement under simulated environmental conditions.

    Science.gov (United States)

    Lu, Huixia; Wei, Fang; Tang, Jingchun; Giesy, John P

    2016-03-15

    Leaching of metals from cement under various environmental conditions was measured to evaluate their environmental safety. A cement product containing clinker, which was produced from cement kiln co-processing of hazardous wastes, was solidified and leaching of metals was characterized using the 8-period test. Concentrations and speciation of metals in cements were determined. Effects of ambient environment and particle size on leachability of metals and mineralogical phases of cement mortars were evaluated by use of XRD and SEM. Results indicated that metals in cements were leachable in various media in descending order of: sea water, groundwater and acid rain. Cr, Ni, As, Co and V were leached by simulated sea water, while Cu, Cd, Pb, Zn, Mn, Sb and Tl were not leached in simulated sea water, groundwater or acid rain. When exposed to simulated acid rain or groundwater, amounts of Cr, Ni, As and V leached was inversely proportional to particle size of cement mortar. According to the one-dimensional diffusion equation, Cr was most leachable and the cumulative leached mass was predicted to be 9.6 mg kg(-1) after 20 years. Results of this study are useful in predicting releases of metals from cement products containing ash and clinkers cement kiln co-processing of hazardous wastes, so that they can be safely applied in the environment.

  17. Investigation of pyrochlore-based U-bearing ceramic nuclear waste: uranium leaching test and TEM observation.

    Science.gov (United States)

    Xu, Huifang; Wang, Yifeng; Zhao, Pihong; Bourcier, William L; Van Konynenburg, Richard; Shaw, Henry F

    2004-03-01

    A durable titanate ceramic waste form (Synroc) with pyrochlore (Ca(U,Pu)Ti2O7) and zirconolite (CaZrTi2O7) as major crystalline phases has been considered to be a candidate for immobilizing various high-level wastes containing fissile elements (239Pu and 235U). Transmission electron microscopy study of a sintered ceramic with stoichiometry of Ca(U(0.5)Ce(0.25)Hf(0.25))Ti2O7 shows the material contains both pyrochlore and zirconolite phases and structural intergrowth of zirconolite lamellae within pyrochlore. The (001) plane of zirconolite is parallel to the (111) plane of pyrochlore because of their structural similarities. The pyrochlore is relatively rich in U, Ce, and Ca with respect to the coexisting zirconolite. Average compositions for the coexisting pyrochlore and zirconolite at 1350 degrees C are Ca(1.01)(Ce3+(0.13)Ce4+(0.19)U(0.52)Hf(0.18))(Ti(1.95)Hf(0.05))O7 (with U/(U + Hf) = 0.72) and (Ca(0.91)Ce(0.09))(Ce3+(0.08)U(0.26)Hf(0.66)Ti(0.01))Ti(2.00)O7 (with U/(U + Hf) = 0.28), respectively. A single pyrochlore (Ca(U,Hf)Ti2O7) phase may be synthesized at 1350 degrees C if the ratio of U/(U + Hf) is greater than 0.72, and a single zirconolite (Ca(Hf,U)Ti2O7) phase may be synthesized at 1350 degrees C if the ratio of U/(U + Hf) is less than 0.28. The synthesized products were used for dissolution tests. The single-pass flow-through dissolution tests show that the dissolution of the U-bearing pyrochlore is incongruent. All the elements are released at differing rates. The dissolution data also show a decrease in rate with run time. The results indicate that a diffusion-controlled process may play a key role during the release of U. TEM observation of the leached pyrochlore directly proves that an amorphous leached layer that is rich in Ti and Hf formed on the surface after the ceramic was leached in pH 4 buffered solution for 835 days. The thickness of the layer ranges from 6 to 10 nm. A nanocrystalline TiO2 phase also forms in the leached layer. The U

  18. A GIS-assisted regional screening tool to evaluate the leaching potential of volatile and non-volatile pesticides

    Science.gov (United States)

    Ki, Seo Jin; Ray, Chittaranjan

    2015-03-01

    A regional screening tool-which is useful in cases where few site-specific parameters are available for complex vadose zone models-assesses the leaching potential of pollutants to groundwater over large areas. In this study, the previous pesticide leaching tool used in Hawaii was revised to account for the release of new volatile organic compounds (VOCs) from the soil surface. The tool was modified to introduce expanded terms in the traditional pesticide ranking indices (i.e., retardation and attenuation factors), allowing the estimation of the leaching fraction of volatile chemicals based on recharge, soil, and chemical properties to be updated. Results showed that the previous tool significantly overestimated the mass fraction of VOCs leached through soils as the recharge rates increased above 0.001801 m/d. In contrast, the revised tool successfully delineated vulnerable areas to the selected VOCs based on two reference chemicals, a known leacher and non-leacher, which were determined in local conditions. The sensitivity analysis with the Latin-Hypercube-One-factor-At-a-Time method revealed that the new leaching tool was most sensitive to changes in the soil organic carbon sorption coefficient, fractional organic carbon content, and Henry's law constant; and least sensitive to parameters such as the bulk density, water content at field capacity, and particle density in soils. When the revised tool was compared to the analytical (STANMOD) and numerical (HYDRUS-1D) models as a susceptibility measure, it ranked particular VOCs well (e.g., benzene, carbofuran, and toluene) that were consistent with other two models under the given conditions. Therefore, the new leaching tool can be widely used to address intrinsic groundwater vulnerability to contamination of pesticides and VOCs, along with the DRASTIC method or similar Tier 1 models such as SCI-GROW and WIN-PST.

  19. Recovering Y and Eu from Waste Phosphors Using Chlorination Roasting—Water Leaching Process

    Directory of Open Access Journals (Sweden)

    Mingming Yu

    2016-10-01

    Full Text Available Recovering Y and Eu from waste phosphors using chlorination roasting followed by a water leaching process was investigated in this study. Firstly, by chlorination roasting and water leaching, Y and Eu elements present in waste phosphors were efficiently extracted into a leach solution. Secondly, the majority of the impurities in the solution can be removed by adjusting the pH to 4.5 using a Na2S and NH3·H2O solution. Thirdly, the rare earths can be precipitated afterwards by adding a H2C2O4 solution and adjusting the pH to 2.0. Then rare earth oxides (REOs can be obtained after calcining at 800 °C for 1 h. The characterization study of the waste phosphors and the rare earth oxide products was performed by XRD, XRF, and SEM-EDS analysis to determine the phase and morphological features. Influences of the factors, such as roasting temperatures and time, the addition of ammonium chloride on the roasting of waste phosphors, as well as the pH and the amount of oxalates on the precipitation of Y and Eu, were investigated. The maximum grade (99.84% of mixed rare earth oxides and recovery rate (87.35% of Y and Eu were obtained at the optimized conditions.

  20. OPTIMIZING OF TIO2 SEPARATION FROM BANGKA ILMENITE BY LEACHING PROCESS USING HCL

    Directory of Open Access Journals (Sweden)

    Sayekti Wahyuningsih

    2016-09-01

    Full Text Available Separation of titanium dioxide (TiO2 from ilmenite Bangka has been done byleaching processusing HCl. Before the leaching process, ilmenite was roastedat 900oC for pre-oxidation (preliminary - oxidation. Leaching process carried out by variation of HCl concentration and Fe0 reducing agents. While the re-deposition of dissolved Ti4+ ion achieved by hydrolysis - condensation using 2-propanol-H2O solvents. Leaching the pre-oxidazed ilmenite shows the phase change of pseudobrokite (Fe2TiO5 into hematite (Fe2O3 and synthetic rutile (TiO2. Formation of the synthetic rutile was characterized by the loss of intensity of Fe2TiO5 at 26.65º and the increasing intensity of rutile TiO2 at 27.49º.The dissolution rate of both titanium and iron was found to be increased, generally, by increasing acid concentration in case of HCl as well as by increasing ilmenite: Fe0 ratio. Precipitation of the dissolved titania with 2-propanol -H2Oof 8:2(v /v produced anatase TiO2 due to the hydrolysis and condensation of Ti-tetra isopropoxide complexes.

  1. 石煤焙烧—加压酸浸提钒研究%Study on Roasting-Pressure Acid Leaching of Vanadium from Stone Coal

    Institute of Scientific and Technical Information of China (English)

    黄俊; 张一敏; 黄晶; 刘涛; 薛楠楠

    2015-01-01

    In order to find a process which could increase the leaching velocity of vanadium,roasting-pressure acid leac-hing of vanadium on stone coal from Tongshan in Hubei was investigated. Results showed that,the optimal operation conditions are as followed:the roasting temperature was 850 ℃,the roasting time was 60 min,the kettle pressure was 1. 0 MPa,initial concentration of sulfuric acid was 15%,ratio of liquid to solid was 1. 5 mL/g,leaching temperature was 150 ℃ and leaching time was 120 min,with these conditions the vanadium leaching rate could reach 80. 51%. The changes of mica mineral struc-ture during leaching process were analyzed by Infrared Spectrometry analysis and the effect of temperature on vanadium effi-ciency was studied from the aspect of leaching kinetics. The results indicated that pressure acid leaching could destruct the crystal lattice of mica that was helpful for the release of vanadium and the increase of vanadium leaching efficiency. The leac-hing kinetics analysis results indicated that:effect of leaching temperature on vanadium efficiency was conspicuous,when the leaching temperature ranged from 60 to 120 ℃,the apparent activation energy was 41. 603 kJ/mol and the leaching was con-trolled by surface chemical reaction. When the temperature ranged from 150 to 210 ℃, the apparent activation energy was 4. 319 kJ/mol and the leaching was controlled by inner diffusion of reactants. As pressure acid leaching could raise the leac-hing temperature over 100 ℃,the destruction velocity of mica crystal lattice could be raised effectively and the vanadium leac-hing time could be shorten effectively.%为探索提高石煤中钒的浸出效率,以湖北通山某石煤矿石为研究对象,进行了石煤焙烧—加压酸浸提钒工艺研究. 结果表明:在焙烧温度为850 ℃、焙烧时间为60 min、釜内压力为1. 0 MPa、硫酸初始浓度为15%、液固比为1. 5 mL/g、浸出温度为150 ℃、浸出时间为120 min

  2. 富银低品位锰矿和闪锌矿的联合氧压酸浸%Simultaneous Acid Pressure Leaching of Silver-bearing Low-grade Manganese Ore and Sphalerite Concentrate

    Institute of Scientific and Technical Information of China (English)

    梁铎强; 王吉坤; 汪云华

    2008-01-01

    进行了硫化锌和含银低品位锰矿联合氧压酸浸的小型试验,以考察影响浸出的各种因素,诸如浸出温度、浸出时间、氧分压和搅拌速度.实验在2L的高压釜内进行.实验结果表明,硫化锌和含银低品位锰矿能相互促进浸出,但这种耦合作用须在一定条件下才会起作用.作者对一些浸出做了探讨.为下一步扩大试验的需要,本文给出了合理的浸出条件:浸出温度, 110℃; 浸出时间,2h; 氧分压, 0.6MPa; 硫酸用量, 1.2倍理论用量.%Lab-scale simultaneous acid pressure leaching of sphalerite concentrate and silver-bearing low-grade manganese ore was performed under various conditions to investigate leaching variables, such as leaching temperature, leaching duration, oxygen partial pressure and stirring rate. Such experiments were carried out in a 2 liter autoclave. Experimental results show that sphalerite concentrate and silver-bearing low-grade manganese ore help each other to leach in the simultaneous leaching experiments, but the coupling effect occurs obviously only under given leaching conditions. In this work some leaching mechanisms were proved in the experiments. For the sake of subsequent scale-up experiment, the reasonable conditions of simultaneous leaching are given as follows: leaching temperature, 135℃; leaching duration, 2h; oxygen partial pressure, 0.6MPa; sulfuric acid usage, 1.2.

  3. The side effects of nitrification inhibitors on leaching water and soil salinization in a field experiment

    Energy Technology Data Exchange (ETDEWEB)

    Diez, J. A.; Arauzo, M.; Hernaiz, P.; Sanz, A.

    2010-07-01

    In experiments carried out in greenhouses, some authors have shown that ammonium sulphate induces greater soil acidity and salinity than other sources of N. Moreover, nitrification inhibitors (NI) tend to cause ammonium to accumulate in soil by retarding its oxidation to nitrate. This accumulated ammonium would also have an effect on soil salinity. Consequently, the aim of this paper was to evaluate the soil and leaching water salinization effects associated with adding NI, dicyandiamide (DCD) and dimethylpyrazole-phosphate (DMPP) to ammonium sulphate nitrate (ASN) fertilizer. This experiment was carried out in the field with an irrigated maize crop. Drainage and Na concentration were measured during both seasons (2006 and 2007) and leached Na was determined. The treatments with NI (DCD and DMPP) were associated with greater Na concentrations in soil solutions and consequently higher rates of Na leaching (in 2007, ASN-DCD 1,292 kg Na ha{sup -}1, ASN-DMPP 1,019 kg Na ha{sup -}1). A treatment involving only ASN also increased the Na concentration in soil and the amount of Na leached in relation to the Control (in 2007, ASN 928 kg Na ha{sup -}1 and Control 587 kg Na ha{sup -}1). The increase in the ammonium concentration in the soil due to the NI treatments could have been the result of the displacement of Na ions from the soil exchange complex through a process which finally led to an increase in soil salinity. Treatments including ammonium fertilizer formulated with NI produced a greater degree of soil salinization due to the presence of ammonium from the fertilizer and accumulated ammonium from the nitrification inhibition. (Author) 31 refs.

  4. Tungsten Recovery from Spent SCR Catalyst Using Alkaline Leaching and Ion Exchange

    Directory of Open Access Journals (Sweden)

    Wen-Cheng Wu

    2016-10-01

    Full Text Available The recovery of tungsten (W from a honeycomb-type spent selective catalytic reduction (SCR catalyst using an alkaline leaching–ion exchange method was investigated. Spent SCR catalyst mainly consists of TiO2 and other oxides (6.37% W, 1.57% vanadium (V, and 2.81% silicon (Si, etc.. The ground catalyst was leached at the optimal conditions, as follows: NaOH concentration of 0.3 kg/kg of catalyst, pulp density of 3%, leaching temperature of 70 °C, particle size of −74 μm, and leaching time of 30 min. In this study, the leaching rate values of V and W under the above conditions were 87 wt %, and 91 wt %, respectively. The pregnant solution was then passed through a strong base anion exchange resin (Amberlite IRA900. At high pH conditions, the use of strong base anion exchange resin led to selective loading of divalent WO42− from the solution, because the fraction of two adjacent positively-charged sites on the IRA900 resin was higher and separate from the coexisting VO43−. The adsorbed W could then be eluted with 1 M NaCl + 0.5 M NaOH. The final concentrated W solution had 8.4 g/L of W with 98% purity. The application of this process in industry is expected to have an important impact on the recovery of W from secondary sources of these metals.

  5. Mechanism of electro-generating leaching of chalcopyrite-MnO2 in presence of Acidithiobacillus thiooxidans

    Institute of Scientific and Technical Information of China (English)

    XIAO Li; LIU Jian-she; FANG Zheng; QIU Guan-zhou

    2008-01-01

    A dual cell system with chalcopyrite anode and MnO2 cathode was used to study the relations between time and such data as the electric quantity and the dissolution rates of the two minerals in the electro-generating leaching(EGL) and the bio-electro-generating leaching(BEGL),respectively.The results showed that the dissolution rates for Cu2+ and Fe2+ in BEGL were almost 2 times faster than those in EGL,and nearly 3 times for Mn2+; the electric output increased nearly by 3 times.The oxidation residue of chalcopyrite was represented by TEM and XRD,whose pattern was similar to that of the raw ore in EGL.The mechanism for leaching of CuFeS2-MnO2 in the presence of Acidithiobacillus thiooxidans was proposed as a successive reaction of two independent sub-processes for the anode.The first stage,common to both processes,is dissolution of chalcopyrite to produce Cu2+,Fe2+ and sulfur.The second stage is subsequent oxidization of sulfur only in BEGL,which is the controlling step of the process.However,the dissolution of MnO2 lasts until the reaction of chalcopyrite stops or the ores exhaust in two types of leaching.

  6. Effect of Winter Cover Crops on Soil Nitrogen Availability, Corn Yield, and Nitrate Leaching

    Directory of Open Access Journals (Sweden)

    S. Kuo

    2001-01-01

    Full Text Available Biculture of nonlegumes and legumes could serve as cover crops for increasing main crop yield, while reducing NO3 leaching. This study, conducted from 1994 to 1999, determined the effect of monocultured cereal rye (Secale cereale L., annual ryegrass (Lolium multiflorum, and hairy vetch (Vicia villosa, and bicultured rye/vetch and ryegrass/vetch on N availability in soil, corn (Zea mays L. yield, and NO3-N leaching in a silt loam soil. The field had been in corn and cover crop rotation since 1987. In addition to the cover crop treatments, there were four N fertilizer rates (0, 67, 134, and 201 kg N ha-1, referred to as N0, N1, N2, and N3, respectively applied to corn. The experiment was a randomized split-block design with three replications for each treatment. Lysimeters were installed in 1987 at 0.75 m below the soil surface for leachate collection for the N0, N2, and N3 treatments. The result showed that vetch monoculture had the most influence on soil N availability and corn yield, followed by the bicultures. Rye or ryegrass monoculture had either no effect or an adverse effect on corn yield and soil N availability. Leachate NO3-N concentration was highest where vetch cover crop was planted regardless of N rates, which suggests that N mineralization of vetch N continued well into the fall and winter. Leachate NO3-N concentration increased with increasing N fertilizer rates and exceeded the U.S. Environmental Protection Agency’s drinking water standard of 10 mg N l�1 even at recommended N rate for corn in this region (coastal Pacific Northwest. In comparisons of the average NO3-N concentration during the period of high N leaching, monocultured rye and ryegrass or bicultured rye/vetch and ryegrass/vetch very effectively decreased N leaching in 1998 with dry fall weather. The amount of N available for leaching (determined based on the presidedress nitrate test, the amount of N fertilizer applied, and N uptake correlated well with average NO3

  7. Effect of winter cover crops on soil nitrogen availability, corn yield, and nitrate leaching.

    Science.gov (United States)

    Kuo, S; Huang, B; Bembenek, R

    2001-10-25

    Biculture of nonlegumes and legumes could serve as cover crops for increasing main crop yield, while reducing NO3 leaching. This study, conducted from 1994 to 1999, determined the effect of monocultured cereal rye (Secale cereale L.), annual ryegrass (Lolium multiflorum), and hairy vetch (Vicia villosa), and bicultured rye/vetch and ryegrass/vetch on N availability in soil, corn (Zea mays L.) yield, and NO3-N leaching in a silt loam soil. The field had been in corn and cover crop rotation since 1987. In addition to the cover crop treatments, there were four N fertilizer rates (0, 67, 134, and 201 kg N ha(-1), referred to as N0, N1, N2, and N3, respectively) applied to corn. The experiment was a randomized split-block design with three replications for each treatment. Lysimeters were installed in 1987 at 0.75 m below the soil surface for leachate collection for the N 0, N 2, and N 3 treatments. The result showed that vetch monoculture had the most influence on soil N availability and corn yield, followed by the bicultures. Rye or ryegrass monoculture had either no effect or an adverse effect on corn yield and soil N availability. Leachate NO3-N concentration was highest where vetch cover crop was planted regardless of N rates, which suggests that N mineralization of vetch N continued well into the fall and winter. Leachate NO3-N concentration increased with increasing N fertilizer rates and exceeded the U.S. Environmental Protection Agency's drinking water standard of 10 mg N l(-1) even at recommended N rate for corn in this region (coastal Pacific Northwest). In comparisons of the average NO3-N concentration during the period of high N leaching, monocultured rye and ryegrass or bicultured rye/vetch and ryegrass/vetch very effectively decreased N leaching in 1998 with dry fall weather. The amount of N available for leaching (determined based on the presidedress nitrate test, the amount of N fertilizer applied, and N uptake) correlated well with average NO3-N during

  8. Rectifying systems of ionic membrane caustic soda synchronized debugging%离子膜烧碱整流系统同步调试

    Institute of Scientific and Technical Information of China (English)

    朱琦; 孔强; 王小红

    2011-01-01

    论述了离子膜烧碱整流系统同步调试的原理、步骤和注意事项。%Discusses of rectifying systems for ionic membrane caustic soda synchronized debugging principles, steps and considerations.

  9. Recovery of indium by acid leaching waste ITO target based on neural network%神经网络优化ITO废靶酸浸回收铟

    Institute of Scientific and Technical Information of China (English)

    李瑞迪; 袁铁锤; 范文博; 邱子力; 苏文俊; 钟楠骞

    2014-01-01

    以提高铟浸出率为目标,通过工艺实验结合神经网络研究ITO废靶酸浸的优化工艺。首先,固定其他工艺因素,进行单因素如残酸度、氧化剂加入量、酸浸温度及时间对铟浸出率影响的实验研究。结果表明,增大残酸度可提高铟浸出率;氧化剂的加入可明显提高铟浸出率,但增加到一定程度后浸出率提高不明显;升高温度可明显提高浸出率,但继续升高则会降低铟浸出率;延长浸出时间也可提高铟浸出率。通过反向传播算法的人工神经网络(BPNN)研究多因素的综合作用对铟浸出率的影响规律,预测值与实验值相差很小,表明所建立的BP模型铟浸出率能比较准确地预测。最终,通过BPNN预测以及实验验证,获得高达99.5%浸出率的工艺参数:残酸度50~60 g/L、氧化剂含量10%、浸出温度70°C和浸出时间2 h。%The optimized leaching techniques were studied by technical experiment and neural network optimization for improving indium leaching rate. Firstly, effect of single technical parameter on leaching rate was investigated experimentally with other parameters fixed as constants. The results show that increasing residual acidity can improve leaching rate of indium. Increasing the oxidant content can obviously increase leaching rate but the further addition of oxidant could not improve the leaching rate. The enhancement of temperature can improve the leaching rate while the further enhancement of temperature decreases it. Extension leaching time can improve the leaching rate. On this basis, a BPNN model was established to study the effects of multi-parameters on leaching rate. The results show that the relative error is extremely small, thus the BPNN model has a high prediction precision. At last, optimized technical parameters which can yield high leaching rate of 99.5%were obtained by experimental and BPNN studies:residual acidity 50-60 g/L, oxidant addition

  10. Application of injection of spent caustic sludge into sour water stripper%酸性水汽提塔注废碱渣工艺技术应用

    Institute of Scientific and Technical Information of China (English)

    刘静翔; 黄占修; 耿庆光; 孙宁飞

    2013-01-01

    中国石油化工股份有限公司洛阳分公司液态烃脱硫醇装置废碱渣年产量超过1 kt,原采用碱渣湿式氧化装置脱硫、浓硫酸中和、酸性水限流排放至炼油污水处理场处理工艺.该工艺存在浓硫酸中和碱渣作业风险大、酸性水低温盐结晶堵塞管线,作业过程恶臭气体环境污染大等问题.通过实施酸性水汽提塔注废碱渣技术改造,停用了碱渣湿式氧化装置,不再进行碱渣酸化处理.工业实践表明:废碱渣注入汽提塔后,净化水中约70%的固定铵可去除,酸性水汽提塔蒸汽单耗下降约10 kg/t,对总外排水水质几乎没有影响,取得了良好的经济效益和社会效益.%The liquid hydrocarbon sweetening unit in Sinopec Luoyang Company produced more than 1000 tons of caustic sludge each year.In the original design,the process of wet oxidation desulfurization,sulfuric acid neutralization and controlled sour water drainage to refinery waste water plant for treatment was applied to treat the caustic sludge.This process had the problems of higher operating risk in neutralization of caustic sludge by sulfuric acid and easy plugging of pipelines by low-temperature salt crystallization of sour water and air pollution by foul gas from operation,etc.To solve these problems,the injection of spent caustic sludge was implemented,caustic sludge wet oxidation unit was shutdown and caustic sludge acidification operation was stopped.The above practices in commercial operation show that,after injection of spent caustic sludge into the sour water stripper,70% of fixed ammonium is removed,steam consumption of sour water stripper is reduced by 10 kg/t,there is no impact on the quality of discharge water,and good economic and social benefits have been achieved.

  11. POTENTIAL FOR STRESS CORROSION CRACKING OF A537 CARBON STEEL NUCLEAR WASTE TANKS CONTAINING HIGHLY CAUSTIC SOLUTIONS

    Energy Technology Data Exchange (ETDEWEB)

    Lam, P.; Stripling, C.; Fisher, D.; Elder, J.

    2010-04-26

    The evaporator recycle streams of nuclear waste tanks may contain waste in a chemistry and temperature regime that exceeds the current corrosion control program, which imposes temperature limits to mitigate caustic stress corrosion cracking (CSCC). A review of the recent service history found that two of these A537 carbon steel tanks were operated in highly concentrated hydroxide solution at high temperature. Visual inspections, experimental testing, and a review of the tank service history have shown that CSCC has occurred in uncooled/un-stress relieved tanks of similar construction. Therefore, it appears that the efficacy of stress relief of welding residual stress is the primary corrosion-limiting mechanism. The objective of this experimental program is to test A537 carbon steel small scale welded U-bend specimens and large welded plates (30.48 x 30.38 x 2.54 cm) in a caustic solution with upper bound chemistry (12 M hydroxide and 1 M each of nitrate, nitrite, and aluminate) and temperature (125 C). These conditions simulate worst-case situations in these nuclear waste tanks. Both as-welded and stress-relieved specimens have been tested. No evidence of stress corrosion cracking was found in the U-bend specimens after 21 days of testing. The large plate test was completed after 12 weeks of immersion in a similar solution at 125 C except that the aluminate concentration was reduced to 0.3 M. Visual inspection of the plate revealed that stress corrosion cracking had not initiated from the machined crack tips in the weld or in the heat affected zone. NDE ultrasonic testing also confirmed subsurface cracking did not occur. Based on these results, it can be concluded that the environmental condition of these tests was unable to develop stress corrosion cracking within the test periods for the small welded U-bends and for the large plates, which were welded with an identical procedure as used in the construction of the actual nuclear waste tanks in the 1960s. The

  12. Leaching process of anode slime with high silver and bismuth%高银铋阳极泥浸出工艺研究

    Institute of Scientific and Technical Information of China (English)

    何静; 郭瑞; 蓝明艳; 王灿; 鲁君乐

    2013-01-01

      某厂高银铋阳极泥产粗铋及综合回收有价金属,工艺采用两段浸出法处理此阳极泥,第1段硫酸浸出铜,第2段盐酸浸出铋.分别考察了浸出温度、时间、液固比(质量比)、酸量及氧化剂用量对浸出率的影响.铜的浸出率(液计)96%以上,铋、锑的浸出率(渣计)均在99%以上,铅、银富集于第2段浸出渣中,铅、银渣含Pb 26.63%左右,含Ag 36.77%左右,铅和银的直收率高,分别为97.82%及98.93%.浸出过程为串级联动循环浸出,洗酸洗水均返回下一次浸出,大大地减少了废水量,环境友好.%In order to produce crude bismuth and comprehensively recovery of valuable metals from anode slime with high silver and bismuth ,The process is Two-stage leaching. The first stage is leaching of copper with sulfuric acid and the second stage is leaching of bismuth with hydrochloric acid. Studied on the relationship between the Leaching rate and the leaching temperature, time, ratio of liquid to solid(Quality), dosage of acid and oxidant.The leaching rate (Liquid) of copper is above 96%,and The leaching rate (Slag) of bismuth and antimony are all above 99 %.The lead and silver are enriched in the second stage leaching slag, which containing Pb about 26.63%,Ag about 36.77 %,the direct yield of Pb and Ag are 97.82 % and 98.93 %respectively.The process is cycle leaching, washing water and washing acid are returned to the next leaching, which greatly reduced the amount of wastewater, and good for environmental protection.

  13. A New Process for Leaching of Silver and Zinc From Zinc-silver Residue%从锌银渣中浸出银、锌新工艺研究

    Institute of Scientific and Technical Information of China (English)

    李辉; 刘凯华; 刘岩; 丛自范

    2014-01-01

    Leaching of zinc and silver from zinc-silver residue in sulfuric acid and hydrochloric acid-magnesium chloride system was studied .Zinc-silver residue was leached first using dilute sulfuric acid . The leaching solution was returned to leach zinc .The leaching residue was leached using HCl-magnesium chloride solution ,silver in leaching solution was replaced by iron plate .Influences of magnesium chloride concentration ,leaching temperature ,leaching time ,ratio between liquid volume and solid mass ,and others fractors on leaching rate of silver and zinc were investigated .The experimental results show that the recovery rate of silver and zinc are 85 .26% and 89 .46% , respectively under the optimum conditions .%研究了用硫酸及盐酸-氯化镁体系从锌银渣中浸出银和锌。先用稀硫酸浸出锌银渣中的部分锌、铁,使银、铅富集在浸出渣中,再硫酸浸出渣用盐酸-氯化镁溶液浸出银、锌,然后用铁板置换回收浸出液中的银。考察了氯化镁浓度、浸出温度、浸出时间、液固体积质量比及其他因素对银浸出率的影响。试验结果表明,在最佳条件下,银回收率为85.26%,锌回收率为89.46%。

  14. Polymer structure modifications for immersion leaching and watermark control

    Science.gov (United States)

    Lee, Jae Woo; Oh, Seung Keun; Kim, Jung Woo; Lee, Sang Hyang; Jeong, Young Ho; Kim, Sang Soo; Park, Myoung Hwan; Kim, Deogbae; Kim, Jaehyun; Lee, Geunsu; Moon, Seung-Chan

    2006-03-01

    Immersion materials have to overcome immersion-issues for successful wet process introduction to semiconductor mass production. Component-leaching issue is one of the most influential wet process huddles, which is related to immersion-liquid and projection lens contamination as well as resist patterning performances. In this paper, we will introduce our experimental results of leaching blocking effects resulted from the modification of polymer and additive structures and from the application of top surface blocking layers. PAG-leaching level of resist film formed of low Tg resin shows the highest meanwhile that of high Tg resin is the smallest leaching value. The interaction forces between additives and resin platforms are the most important to prevent additives leaching to immersion liquid. We have tested 3 different types of resin structures to modify the interaction forces between resin platform and resist components especially PAG molecules and photo-generated acid molecules. We changed 2-hydroxyethyl methacrylate(2-HEMA) contents to be 5, 10, 15% in our base resin, COMA-acrylate hybrid system to modify the hydrophilicity of resist platforms. By mimicking immersion process to obtain wet-performance of their resists we have obtained relative value of component-leaching. Interaction-force between resist platform and PAG was seemed to be largest when resist component-leaching is least so that the pattern profiles become to be vertical. It was appeared that the 5% 2-HEMA containing resin and TPS-Nonaflate PAG system showed the best performance because of its low leaching resulted from their strong interaction forces. Another polymer parameter to determine the component-diffusivity is glass transition temperature, Tg. Low Tg means high mobility of resin by small thermal energy due to high free volume contents inside of the resist film which can act as diffusion pathways of resist components. 10% MA resin system shows the lowest Tg, around 140 degrees C and the most

  15. INFLUENCE OF LOADING RATE ON DYNAMIC FRACTURE BEHAVIOR OF FIBER-REINFORCED COMPOSITES

    Institute of Scientific and Technical Information of China (English)

    Kezhuang Gong; Zheng Li; Weizhong Qin

    2008-01-01

    The effect of loading rate on the dynamic fracture properties and the failure mechanisms of glass fiber-reinforced composite materials under mode I fracture is studied.Dynamic reflective caustic experiments are carried out for two loading rates.By measuring the characteristic dimensions of the shadow spots during the caustic experiments,the dynamic SIFs are calculated for different loading rates.The experimental results indicate that the dynamic fracture toughness KId increases remarkably with increasing loading rate,and the crack grows faster under the high-velocity impact.Moreover,by examining the crack growth routes and the fracture surfaces,it is shown that the loading rate also greatly affects the failure mechanisms at micro-scale.

  16. Kinetics of oxidative leaching of ocean polymetallic nodules in molten potassium hydroxide medium

    Institute of Scientific and Technical Information of China (English)

    WANG Yun-shan; LI Zuo-hu; LI Hao-ran

    2005-01-01

    The kinetics of oxidative leaching of ocean polymetallic nodules in molten potassium hydroxide medium was investigated in terms of the gas-flow rate, stirring rate, reaction time, reaction temperature and partial pressure of oxygen on the ratio of manganese conversion in ocean polymetallic nodules. The category of the rate controlling step was determined. The process of the liquid-phase oxidation reaction can be described by surface chemical reaction-controlled non-reaction shrinking core model(SCM), the apparent activation energy was achieved and the rate equation was put forward. From the equation, it can be concluded that the reaction rate mainly depends on the reaction temperature and the partial pressure of oxygen.

  17. Assessment of leaching potential of highly leaded jewelry.

    Science.gov (United States)

    Weidenhamer, Jeffrey D; Newman, Breinn E; Clever, Ashley

    2010-05-15

    Lead is a potent neurotoxin particularly toxic to young children, and in response to recent poisonings of children and high levels of lead contamination in children's jewelry, US regulatory standards for lead content in these items have become much more stringent. Parents are often advised to throw out suspect items in the trash. While household wastes are generally exempt from consideration as hazardous waste, the potential for leaching of hazardous quantities of lead from such items is unknown. A modified Toxicity Characteristic Leaching Procedure (TCLP), in which intact jewelry components were subjected to leaching, was used to evaluate the potential for leaching of lead from highly leaded jewelry. Of 62 jewelry components tested, 61 exceeded the US regulatory standard for lead of 5mg/L, and leachate lead concentrations averaged 1460 mg/L. Twenty-six of the component items tested yielded TCLP lead concentrations exceeding 1000 mg/L. These results demonstrate that highly leaded jewelry items may leach significant amounts of lead, and provide another reason to remove lead from these products. Furthermore, these results suggest that while the volume of such items in the municipal solid waste (MSW) stream is small, they have the potential to contribute significant quantities of lead to MSW leachates.

  18. Leaching hydrodynamics of weathered elution-deposited rare earth ore

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Both porosity (φ) and permeability (k) of the weathered elution-deposited rare earth ores are basic hydrodynamic parameters for RE leaching. The relationship between k and φ of two typical rare earth ores of South China in the packed bed was investigated by measuring the flow (Q) under various leaching pressure difference (Δp). The experimental results show that the relationship between k and φ is unique, moreover the relationship between Q and Δp is in accord with the Darcy's law. The effects of the type of ores, the leaching reagents and its concentration, the granule ore size on the leaching permeability have also been investigated. It is demonstrated that kH (for heavy RE ore, kH=35.98 mm2)>kM-H (for middle-heavy RE ore,kM-H=28.50 mm2), whereas k(NH4NO3)>k(NH4Cl)>k[(NH4)2SO4], and the k value increases with increasing leaching reagents concentration and granule ore size(k0.60~0.75 mm=99.96 mm2,k0.125~0.60 mm=11.83 mm2, k0.074~0.125 mm=0.84 mm2).

  19. Bryan Mound SPR cavern 113 remedial leach stage 1 analysis.

    Energy Technology Data Exchange (ETDEWEB)

    Rudeen, David Keith; Weber, Paula D.; Lord, David L.

    2013-08-01

    The U.S. Strategic Petroleum Reserve implemented the first stage of a leach plan in 2011-2012 to expand storage volume in the existing Bryan Mound 113 cavern from a starting volume of 7.4 million barrels (MMB) to its design volume of 11.2 MMB. The first stage was terminated several months earlier than expected in August, 2012, as the upper section of the leach zone expanded outward more quickly than design. The oil-brine interface was then re-positioned with the intent to resume leaching in the second stage configuration. This report evaluates the as-built configuration of the cavern at the end of the first stage, and recommends changes to the second stage plan in order to accommodate for the variance between the first stage plan and the as-built cavern. SANSMIC leach code simulations are presented and compared with sonar surveys in order to aid in the analysis and offer projections of likely outcomes from the revised plan for the second stage leach.

  20. Simultaneous leaching and carbon sequestration in constrained aqueous solutions.

    Science.gov (United States)

    Moon, Ji-Won; Cho, Kyu-Seong; Moberly, James G; Roh, Yul; Phelps, Tommy J

    2011-12-01

    The behavior of metal ions' leaching and precipitated mineral phases of metal-rich fly ash (FA) was examined in order to evaluate microbial impacts on carbon sequestration and metal immobilization. The leaching solutions consisted of aerobic deionized water (DW) and artificial eutrophic water (AEW) that was anaerobic, organic- and mineral-rich, and higher salinity as is typical of bottom water in eutrophic algae ponds. The Fe- and Ca-rich FAs were predominantly composed of quartz, mullite, portlandite, calcite, hannebachite, maghemite, and hematite. After 86 days, only Fe and Ca contents exhibited a decrease in leaching solutions while other major and trace elements showed increasing or steady trends in preference to the type of FA and leaching solution. Ca-rich FA showed strong carbon sequestration efficiency ranging up to 32.3 g CO(2)/kg FA after 86 days, corresponding to almost 65% of biotic carbon sequestration potential under some conditions. Variations in the properties of FAs such as chemical compositions, mineral constituents as well as the type of leaching solution impacted CO(2) capture. Even though the relative amount of calcite increased sixfold in the AEW and the relative amount of mineral phase reached 37.3 wt% using Ca-rich FA for 86 days, chemical sequestration did not accomplish simultaneous precipitation and sequestration of several heavy metals.

  1. Alkaline Leaching of Low Zinc Content Iron-Bearing Sludges

    Directory of Open Access Journals (Sweden)

    Gargul K.

    2016-03-01

    Full Text Available Various types of waste materials containing zinc (e.g. dusts and sludges from gas dedusting process are obtained in steel industry. The contents of Zn in these materials may vary considerably. Even a low concentration of zinc in recirculated products precludes their recycling in ferrous metallurgy aggregates. Long storage of this type of material can lead to contamination of soil and water by zinc compounds which can be leached out by acid rain, for example. This paper focuses on research involving alkaline leaching tests of low zinc content iron-bearing materials. These tests were preceded by the analysis of the elemental, phase and grain size composition, and analysis of the thermodynamic conditions of the leaching process. The main aim of research was to decrease the content of the zinc in the sludge to the level where it is suitable as an iron-bearing material for iron production (~1% Zn. Leaching at elevated temperatures (368 K, 60 min has led to a decrease in the zinc content in the sludge of about 66%. The research revealed that long hour leaching (298 K, 100 hours carried out at ambient temperatures caused a reduction in zinc content by 60% to the value of 1.15-1.2% Zn.

  2. Simultaneous leaching and carbon sequestration in constrained aqueous solutions

    Energy Technology Data Exchange (ETDEWEB)

    Phelps, Tommy Joe [ORNL; Moon, Ji Won [ORNL; Roh, Yul [Chonnam National University, Gwangju; Cho, Kyu Seong [ORNL

    2011-01-01

    The behavior of metal ions leaching and precipitated mineral phases of metal-rich fly ash (FA) was examined in order to evaluate microbial impacts on carbon sequestration and metal immobilization. The leaching solutions consisted of aerobic deionized water (DW) and artificial eutrophic water (AEW) that was anaerobic, organic- and mineral-rich, and higher salinity as is typical of bottom water in eutrophic algae ponds. The Fe- and Ca-rich FAs were predominantly composed of quartz, mullite, portlandite, calcite, hannebachite, maghemite, and hematite. After 86 days, only Fe and Ca contents exhibited a decrease in leaching solutions while other major and trace elements showed increasing or steady trends in preference to the type of FA and leaching solution. Ca-rich FA showed strong carbon sequestration efficiency ranging up to 32.3 g CO(2)/kg FA after 86 days, corresponding to almost 65% of biotic carbon sequestration potential under some conditions. Variations in the properties of FAs such as chemical compositions, mineral constituents as well as the type of leaching solution impacted CO(2) capture. Even though the relative amount of calcite increased sixfold in the AEW and the relative amount of mineral phase reached 37.3 wt% using Ca-rich FA for 86 days, chemical sequestration did not accomplish simultaneous precipitation and sequestration of several heavy metals.

  3. Bioleaching of refractory gold ore (Ⅲ)--Fluid leaching Jinya refractory gold concentrate by Thiobacillus ferrooxidans

    Institute of Scientific and Technical Information of China (English)

    闵小波; 柴立元; 陈为亮; 于霞; 张传福; 邝中

    2002-01-01

    A novel fluidized-bed reactor was designed and installed for bioleaching in a semi-continuous way,by which a process for bioleaching-cyanidation of Jinya refractory gold arsenical concentrate was studied.The arsenic extraction rate reaches 82.5% after 4-day batch biooxidation of the concentrate under the optimized condition of pH 2.0,ferric ion concentration 6.5 g/L and pulp concentration 10%.And leached rate of gold in the following cyanidation is over 90%.The parameters of three series fluidized-bed reactors exhibit stability during the semi-continuous bioleaching of the concentrate.Arsenic in the concentrate can be got rid of 91% after 6-day leaching.Even after 4 days,82% of arsenic extraction rate was still obtained.The recovery rates of gold are 92% and 87.5% respectively in cyaniding the above bioleached residues.The results will provide a base for further commercial production of gold development.

  4. Pretreatment of copper-bearing refractory gold ores by bio-heap leaching

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    The refractory gold ores associated with rich copper and trapped in pyrite and quartz were studied. With conventional technique (all-sliming cyanidation), the gold recovery rate is only 51.78%. To eliminate the negative effects of copper and pyrite on cyanidation and increase the gold recovery rate, the investigation on bio-heap leaching pretreatment was made, by which Cu would be dissolved and gold would be liberated from pyrite. The experiment adopted mixed bacteria, mainly Thiobacillus ferrooxidan (named T. f1), as the bacterial catalyst for bio-preconditioning and was carried out in a PVC column with a diameter of 20 cm and a height of 1.3 m loaded with gold ores. The temperature was controlled between 28 and 30℃, the pH value was kept between 2.0-2.5,and the flux of sprinkling bacterial liquid was maintained 0.80 L/h. After 45-day's bio-oxidization, among the samples sizing from 0to 5 mm, the oxidation rates of Cu, Fe and S were respectively 44.62%, 28.16% and 25.46%, and the gold recovery rate by cyaniding increased to 80.35%. The bio-heap leaching pretreatment can therefore effectively dissolve Cu and liberate gold from pyrite and lead to the increase of gold extraction.

  5. INVESTIGATION OF THE POTENTIAL FOR CAUSTIC STRESS CORROSION CRACKING OF A537 CARBON STEEL NUCLEAR WASTE TANKS

    Energy Technology Data Exchange (ETDEWEB)

    Lam, P.

    2009-10-15

    The evaporator recycle streams contain waste in a chemistry and temperature regime that may be outside of the current waste tank corrosion control program, which imposes temperature limits to mitigate caustic stress corrosion cracking (CSCC). A review of the recent service history (1998-2008) of Tanks 30 and 32 showed that these tanks were operated in highly concentrated hydroxide solution at high temperature. Visual inspections, experimental testing, and a review of the tank service history have shown that CSCC has occurred in uncooled/un-stress relieved F-Area tanks. Therefore, for the Type III/IIIA waste tanks the efficacy of the stress relief of welding residual stress is the only corrosion-limiting mechanism. The objective of this experimental program is to test carbon steel small scale welded U-bend specimens and large welded plates (12 x 12 x 1 in.) in a caustic solution with upper bound chemistry (12 M hydroxide and 1 M each of nitrate, nitrite, and aluminate) and temperature (125 C). These conditions simulate worst-case situations in Tanks 30 and 32. Both as-welded and stress-relieved specimens have been tested. No evidence of stress corrosion cracking was found in the U-bend specimens after 21 days of testing. The large plate test is currently in progress, but no cracking has been observed after 9 weeks of immersion. Based on the preliminary results, it appears that the environmental conditions of the tests are unable to develop stress corrosion cracking within the duration of these tests.

  6. Round robin testing of a percolation column leaching procedure.

    Science.gov (United States)

    Geurts, Roeland; Spooren, Jeroen; Quaghebeur, Mieke; Broos, Kris; Kenis, Cindy; Debaene, Luc

    2016-09-01

    Round robin test results of a percolation column leaching procedure (CEN/TS 14405:2004), organised by the Flemish Institute for Technological Research (VITO), over a time span of 13years with a participation of between 8 and 18 different laboratories are presented and discussed. Focus is on the leachability of heavy metals As, Cd, Cr, Cu, Hg, Ni, Pb and Zn from mineral waste materials. By performing statistical analyses on the obtained results, insight into the reproducibility and repeatability of the column leaching test is gathered. A ratio of 1:3 between intra- and inter-laboratory variability is found. The reproducibility of the eluates' element concentrations differ significantly between elements, materials and fractions (i.e. different liquid-to-solid ratios). The reproducibility is discussed in light of the application of the column leaching test for legal and environmental policy purposes. In addition, the performances of laboratories are compared.

  7. Incorporating Fault Tolerance in LEACH Protocol for Wireless Sensor Networks

    Directory of Open Access Journals (Sweden)

    Rudranath Mitra

    2012-06-01

    Full Text Available Routing protocols have been a challenging issue in wireless sensor networks. WSN is one of the focussed are of research because of its multi-aspect applications. These networks are self-organized using clustering algorithms to conserve energy. LEACH (Low-Energy Adaptive Clustering Hierarchy protocol[1] is one of the significant protocols for routing in WSN. In LEACH, sensor nodes are organized in several small clusters where there are cluster heads in each cluster. These CHs gather data from their local clusters aggregate them & send them to the base station. On the LEACH many new schemes have been proposed to enhance its activity like its efficiency, security etc. In this paper the fault tolerance issue is being incorporated.

  8. Influence of soil structure on contaminant leaching from injected slurry

    DEFF Research Database (Denmark)

    Amin, M. G. Mostofa; Pedersen, Christina Østerballe; Forslund, Anita;

    2016-01-01

    macropore flow paths. The slurry constituents that ended up in or near the macropore flow paths of the intact soil were presumably washed out relatively quickly in the first event. For the last three events the intact soil leached fewer microorganisms than the disturbed soil due to the bypassing effect...... and persistence of nitrogen, microorganisms (bacteriophage, E. coli, and Enterococcus) and a group of steroid hormone (estrogens) were investigated after injection of swine slurry into either intact (structured) or disturbed (homogeneous repacked) soil. The slurry was injected into hexaplicate soil columns...... of water through the macropore flow path in the intact soil. Estrogen leached from the intact soil in the first event only, but for the disturbed soil it was detected in the leachates of last two events also. Leaching from the later events was attributed to higher colloid transport from the disturbed soils...

  9. Ee-Leach(Low Energy Adaptive Clustering Hierarchy Modified Protocol

    Directory of Open Access Journals (Sweden)

    Nishita Payar,

    2014-05-01

    Full Text Available A wireless sensor network is made by many homogeneous and/or nodes which can sense data and communicate to each other. As energy is a scarce resource in WSN, the main issue is energy efficient routing. Many flat and hierarchical protocols have been projected to enhance the network lifetime. Low Energy Adaptive Clustering Hierarchy (LEACH protocol is a basic energy efficient hierarchical routing protocol in WSN. In LEACH, cluster heads are selected and cluster is formed by joining non cluster head nodes. Member nodes transmit the data to respective cluster head and the cluster head is conscientious to transmit the gathered and aggregated data directly to the base station. This paper examines the performance of the conventional LEACH protocol and gives an enhancement to it for energy efficiency. The proposed protocol considers many parameters like residual energy and distance from base station etc. for cluster head selection and energy efficient routing.

  10. BACTERIAL LEACHING OF ELECTRONIC SCRAP: INFLUENCE OF PROCESS PARAMETERS

    Directory of Open Access Journals (Sweden)

    Luciana Harue Yamane

    2013-03-01

    Full Text Available The application of bacterial leaching in the ore treatment is already known and also can be applied such as treatment of electronic waste to copper recovery. This paper investigates the influence of process parameters (pulp density, inoculums volume, rotation speed and initial concentration of ferrous iron on bacterial leaching of copper from printed circuit board of computers using the bacterium Acidithiobacillus ferrooxidans–LR. Printed circuit boards from computers were comminuted using a hammer mill. The powder obtained was magnetically separated and the non-magnetic material used in this study. A shake flask study was carried out on the non-magnetic material using a shaker. The results show that Acidithiobacillus ferrooxidans–LR can leach 99% of copper from printed circuit boards (non–magnetic material under the determined conditions through of the studies.

  11. The influence of process parameters on desulfurization of Mezino coal by HNO{sub 3}/HCl leaching

    Energy Technology Data Exchange (ETDEWEB)

    Alam, H.G.; Moghaddam, A.Z.; Omidkhah, M.R. [Chemical Engineering Department, Tarbiat Modares University, Tehran (Iran)

    2009-01-15

    Coal desulfurization prior to usage is a preprocessing in order to achieve clean fuel and reduce environmental impacts such as acid rain. Desulfurization of Tabas Mezino coal was conducted with two consecutive steps of froth flotation at ambient temperature followed by leaching at various conditions. Reducing the ash content of Mezino coal by 35.7 wt.% and its total sulfur content by 36.9% using froth flotation process was successful. HCl and HNO{sub 3} were used, separately, to leach the floated coal, and the effectiveness of each acid on Mezino coal desulfurization was investigated. Nitric acid was found to be much more effective than HCl and the effects of reaction time, acid concentration and temperatures as well as stirring speed were studied as major parameters in the nitric leaching process. Taguchi orthogonal experiment with the above mentioned parameter elements; one at three levels was used to optimize the experiment parameters by the analysis of variances. Applying of the Taguchi technique significantly reduced the time and cost required for the experimental investigation. The findings indicated that acid concentration, with a high contribution, had the most dominant effect on desulfurization performance, followed by temperature, stirring speed and time. Accordingly, the optimum condition was obtained as, temperature: 90 C., acid concentration: 30%., and stirring rate: 1000 rpm. The total sulfur and ash removal after flotation and leaching at optimum condition reached to 75.4 and 53.2% respectively that is a remarkable result compared to the previous works. (author)

  12. Reuse of cement-solidified municipal incinerator fly ash in cement mortars: physico-mechanical and leaching characteristics.

    Science.gov (United States)

    Cinquepalmi, Maria Anna; Mangialardi, Teresa; Panei, Liliana; Paolini, Antonio Evangelista; Piga, Luigi

    2008-03-01

    The reuse of cement-solidified Municipal Solid Waste Incinerator (MSWI) fly ash (solidified/stabilised (S/S) product) as an artificial aggregate in Portland cement mortars was investigated. The S/S product consisted of a mixture of 48 wt.% washed MSWI fly ash, 20 wt.% Portland cement and 32 wt.% water, aged for 365 days at 20 degrees C and 100% RH. Cement mortars (water/cement weight ratio=0.62) were made with Portland cement, S/S product and natural sand at three replacement levels of sand with S/S product (0%, 10% and 50% by mass). After 28 days of curing at 20 degrees C and 100% RH, the mortar specimens were characterised for their physico-mechanical (porosity, compressive strength) and leaching behaviour. No retardation in strength development, relatively high compressive strengths (up to 36 N/mm2) and low leaching rates of heavy metals (Cr, Cu, Pb and Zn) were always recorded. The leaching data from sequential leach tests on monolithic specimens were successfully elaborated with a pseudo-diffusional model including a chemical retardation factor related to the partial dissolution of contaminant.

  13. Leaching heavy metals from the surface soil of reclaimed tidal flat by alternating seawater inundation and air drying.

    Science.gov (United States)

    Guo, Shi-Hong; Liu, Zhen-Ling; Li, Qu-Sheng; Yang, Ping; Wang, Li-Li; He, Bao-Yan; Xu, Zhi-Min; Ye, Jin-Shao; Zeng, Eddy Y

    2016-08-01

    Leaching experiments were conducted in a greenhouse to simulate seawater leaching combined with alternating seawater inundation and air drying. We investigated the heavy metal release of soils caused by changes associated with seawater inundation/air drying cycles in the reclaimed soils. After the treatment, the contents of all heavy metals (Cd, Pb, Cr, and Cu), except Zn, in surface soil significantly decreased (P removal rates ranging from 10% to 51%. The amounts of the exchangeable, carbonate, reducible, and oxidizable fractions also significantly decreased (P heavy metals. Measurement of diffusive gradients in thin films indicated that seawater inundation significantly increased the re-mobility of heavy metals. During seawater inundation, iron oxide reduction induced the release of heavy metals in the reducible fraction. Decomposition of organic matter, and complexation with dissolved organic carbon decreased the amount of heavy metals in the oxidizable fraction. Furthermore, complexation of chloride ions and competition of cations during seawater inundation and/or leaching decreased the levels of heavy metals in the exchangeable fraction. By contrast, air drying significantly enhanced the concentration of heavy metals in the exchangeable fraction. Therefore, the removal of heavy metals in the exchangeable fraction can be enhanced during subsequent leaching with seawater.

  14. Synergistic Effect of Nanosilica Aerogel with Phosphorus Flame Retardants on Improving Flame Retardancy and Leaching Resistance of Wood

    Directory of Open Access Journals (Sweden)

    Xiaodan Zhu

    2014-01-01

    Full Text Available Nanosilica (Nano-SiO2 sol fabricated by a sol-gel process was introduced into wood modification with phosphorus flame retardants to improve the flame retardancy and leaching resistance of wood. The obtained materials were characterized by scanning electron microscopy and energy dispersive spectrometer (SEM-EDS, thermogravimetric analysis (TGA, cone calorimetric (CONE, and infrared spectroscopy (FT-IR. The residual rate of flame retardants before and after leaching was determinated by a leaching resistance. The results showed that the phosphorus flame retardants and SiO2 sol could reside in the poplar wood and are widely distributed in the vessels, pits, wood timber, and the spaces between wood cells of poplar substrate. TGA and CONE results indicated that the introduction of nano-SiO2 aerogel with phosphorus flame retardants had a significantly synergistic effect on improving the flame retardancy and inhibiting the release of smoke and toxic gases. In addition, the leaching resistance test, combined with infrared analysis and EDS analysis, confirmed that the phosphorus flame retardants were able to be fixed by SiO2 aerogel in the wood.