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Sample records for acid leaching present

  1. Acid leaching of uranium present in a residue from mining industry

    Energy Technology Data Exchange (ETDEWEB)

    Braulio, Walace S.; Ladeira, Ana C.Q. [Center for Development of Nuclear Technology (CDTN/CNEN-MG), Belo Horizonte, MG (Brazil). Dept. of Mineral Technology

    2011-07-01

    The acid mine drainage is one of the most important environmental problems associated with mining of ores containing sulfides. The treatment of these acid effluents, which contains high concentrations of dissolved metals and anions, is generally by liming. The wastes generated in the liming process may present significant toxicity and their storage in inappropriate places waiting for treatment is a common issue that requires solution. Osamu Utsumi Mine located in the city of Caldas, Minas Gerais, has been facing this problem. The residue of this mine consists of an alkaline sludge generated from the neutralization of the pH of acid mine drainage and is rich in various metals, including uranium. The main concern is the long term stability of this residue, which is in permanent contact with the acid water in the open pit. The recovery of uranium by hydrometallurgical techniques, such as acid leaching, can be a viable alternative on the reuse of this material. This study aimed at establishing a specific leaching process for the recovery of uranium present in the sludge from Caldas uranium mine. Some parameters such as solid/liquid ratio (0.09 to 0.17), time of leaching (1 to 24 hours) and concentration of sulfuric acid (pH from 0 to 3.0) were assessed. The results showed that it is possible to extract 100% of uranium present in the sludge. The concentration of U{sub 3}O{sub 8} in the residue was 0.25%, similar to the content of the vein ores which is around 0.20% to 1.0%. The best experimental leaching condition is solid/liquid ratio of 0.17, pH 1.0 and 2 hours of reaction at room temperature (25 deg C). The content of uranium in the liquor is around 440 mgL{sup -1}. The recovery of the uranium from the liquor is under investigation by ionic exchange. (author)

  2. 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.

  3. 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.

  4. 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.

  5. Caro's acid - its introduction to uranium acid leaching in Australia

    International Nuclear Information System (INIS)

    After extensive testing and plant trials to establish the benefits of Caro's acid (H2SO5) as an alternative oxidant, Queensland Mines Limited decided to replace pyrolusite with Caro's acid in its acid leach uranium treatment plant at Nabarlek. The decision was based on the reagent savings and environmental gains associated with the removal of manganese from the process liquors, as well as the labour savings and improved oxidation reduction potential control possible in leaching using the Caro's acid system. Some changes in operating parameters were necessary with the introduction of Caro's acid to the treatment plant. Operating results have confirmed the relationship between oxidant demand and uranium content of ore established during the trials. Acid savings have been as predicted from the plant trials. The major saving has been of hydrated lime required for tailings neutralisation

  6. In situ leaching of uranium

    International Nuclear Information System (INIS)

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

  7. Manual of acid in situ leach uranium mining technology

    International Nuclear Information System (INIS)

    In situ leaching (ISL) technology recovers uranium using two alternative chemical leaching systems - acid and alkaline. This report brings together information from several technical disciplines that are an essential part of ISL technology. They include uranium geology, geohydrology, chemistry as well as reservoir engineering and process engineering. This report provides an extensive description of acid ISL uranium mining technology

  8. Pb(II) leaching from waste CRT funnel glass in nitric acid solutions

    OpenAIRE

    A. Strzałkowska; M. Wojtala; J. Siwka

    2012-01-01

    Purpose: The paper presents experimental results of Pb (II) leaching from waste CRT funnel glass using solution of nitric acid (V) . This work focused on examining the impact of concentration and particle size on the leaching percentage of Pb (II) from funnel glass.Design/methodology/approach: Material for the investigation was crushed and sieved. Leaching was carried out using working solutions pfrom co repared ncentrated HNO3 and mechanical stirrer.Findings: The received results show the po...

  9. Mechanochemical leaching of chalcopyrite concentrate by sulfuric acid

    Institute of Scientific and Technical Information of China (English)

    Sina Hejazi; Jalil Vahdati khaki; Abolfazl Babakhani

    2016-01-01

    This study aimed to introduce a new cost-effective methodology for increasing the leaching efficiency of chalcopyrite concentrates at ambient temperature and pressure. Mechanical activation was employed during the leaching (mechanochemical leaching) of chalcopyrite concentrates in a sulfuric acid medium at room temperature and atmospheric pressure. High energy ball milling process was used during the leaching to provide the mechanochemical leaching condition, and atomic absorption spectroscopy and cyclic voltammetry were used to de-termine the leaching behavior of chalcopyrite. Moreover, X-ray diffraction and scanning electron microscopy were used to characterize the chalcopyrite powder before and after leaching. The results demonstrated that mechanochemical leaching was effective; the extraction of copper increased significantly and continuously. Although the leaching efficiency of chalcopyrite was very low at ambient temperature, the percentages of copper dissolved in the presence of hydrogen peroxide (H2O2) and ferric sulfate (Fe2(SO4)3) after 20 h of mechanochemical leaching reached 28%and 33%, respectively. Given the efficiency of the developed method and the facts that it does not require the use of an autoclave and can be conducted at room temperature and atmospheric pressure, it represents an economical and easy-to-use method for the leaching industry.

  10. Leaching of vanadium from sulphuric acid manufacture spent catalysts

    OpenAIRE

    García, Diego Juan; Lozano Blanco, Luis Javier; Mulero Vivancos, María Dolores

    2001-01-01

    Recovery of vanadium contained in spent catalysts from the manufacture of sulphuric acid has been studied in this work, resulting in an industrial multistage process for the treatment of them avoiding direct deposition or dumping. Characterization of supplied spent catalysts samples, confirmed vanadium levels showed in the literature. The study of variables influencing leaching process: type of leaching agent, leaching agent concentration, S/L ratio, stirring speed and temperature, allows to ...

  11. Canopy leaching of subtropical mixed forests under acid rain

    Institute of Scientific and Technical Information of China (English)

    Renjun XIANG; Liyuan CHAI; Xilin ZHANG; Gong ZHANG; Guifang ZHAO

    2008-01-01

    Leaching of major ions from acid precipitation in a subtropical forest was examined based on an experi-ment in four sample sites in Shaoshan City, Hunan Province, China, from January 2001 to June 2002. Results clearly show that when rain passed through the canopy, pH increased and the evidence of ion uptake was presented for SO42- , NO3-, Mg2+ and NH4+ ions, espe-cially of NH4+ and NO3-. The percentages of dissolved SO42-, Ca2+ and Mg2+ show a decreasing trend with increasing rainfall. Percentages of leaching Ca2+, K+ and Cl- ions show an increasing trend as a function of increased pH values. The forest canopy in Shaoshan City has a strong effect on the uptake of SO42- and NO3- ions under acid rain conditions. The decreasing order of ions leaching in the forest canopy is as follows: K+> Ca2+ > Cl- > Mg2+ > SO42- > NO3- > NH4+ > Na+.

  12. 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.

  13. Sulfuric acid leaching of mechanically activated manganese carbonate ore

    Directory of Open Access Journals (Sweden)

    Kenan Yıldız

    2010-06-01

    Full Text Available Acidic leaching of mechanically activated manganese ore from Denizli – Tavas was investigated. The ore was activated mechanically in a planetary mill and the amorphisation in manganese structure was analyzed with X-ray diffraction. The parameters in acidic leaching of the ore were milling time, acid concentration and time. All experiments were performed at 25°C with solid to liquid ratio: 1/10. The activation procedure led to amorphization and structural disordering in manganese ore and accelerated the dissolution of manganese in acidic media.

  14. 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.

  15. 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.

  16. Leaching of vanadium from sulphuric acid manufacture spent catalysts

    Directory of Open Access Journals (Sweden)

    García, Diego Juan

    2001-02-01

    Full Text Available Recovery of vanadium contained in spent catalysts from the manufacture of sulphuric acid has been studied in this work, resulting in an industrial multistage process for the treatment of them avoiding direct deposition or dumping. Characterization of supplied spent catalysts samples, confirmed vanadium levels showed in the literature. The study of variables influencing leaching process: type of leaching agent, leaching agent concentration, S/L ratio, stirring speed and temperature, allows to fix the most advantageous conditions using industrial application criterion and verifying that the process is difusión controlled. The work is completed by developing an industrial leaching cycle simulation with the aim of reproducing real performance of spent catalyst, proposing operating conditions, and verifying the non-toxic character of the final residue obtained.

    En el presente trabajo se ha estudiado la recuperación del vanadio contenido en los catalizadores agotados procedentes de la fabricación del ácido sulfúrico, planteando un proceso industrial multietapa para el tratamiento de estos residuos, evitando su deposición o vertido directos. La caracterización de las muestras de catalizadores agotados disponibles confirmó los valores encontrados en la bibliografía. Se estudiaron las variables que influyen en el proceso de lixiviación (tipo de agente de lixiviación y concentración del mismo, relación S/L, velocidad de agitación y temperatura definiendo las condiciones más adecuadas desde el punto de vista industrial y verificando que el proceso está controlado por mecanismos difusionales. El trabajo se completa con la simulación de un ciclo industrial de lavado del catalizador y la verificación de la nula toxicidad de los lixiviados obtenidos por degradación del residuo final. 24 Aplicación de la resistencia de ruido al estudio de pinturas ricas en zinc Noise resistance applied to the study of zinc rich paints

  17. Ultrasound effects on zinc recovery from EAF dust by sulfuric acid leaching

    Science.gov (United States)

    Brunelli, K.; Dabalà, M.

    2015-04-01

    In this work, an ultrasound-assisted leaching process was studied for the recovery of zinc from electric arc furnace (EAF) dust, in which zinc was mainly present in the form of franklinite (60%). Hydrometallurgy is emerging as a preferred process for the recovery of a variety of metals, and the use of ultrasound could offer advantages over the conventional leaching process, especially for the dissolution of franklinite. Franklinite is a refractory phase that is difficult to leach and represents the main obstacle in conventional hydrometallurgy processing. Atmospheric leaching with different sulfuric acid concentrations (0.2-2.0 M) at two temperatures (323 and 353 K) was performed. The tests were conducted using both conventional and ultrasound-assisted leaching. After the leaching tests, the solid residues were characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD) techniques, whereas the leach liquor was analyzed by inductively coupled plasma spectroscopy (ICP). The use of ultrasound facilitated the dissolution of franklinite at low acid concentrations and resulted in a greater zinc recovery under all of the investigated operating conditions.

  18. Nitric acid leaching of polymetallic middlings of concentration

    OpenAIRE

    Rogozhnikov, D. A.; Mamyachenkov, S. V.; Karelov, S. V.; Anisimova, O. S.

    2013-01-01

    Investigations into the nitric acid leaching of polymetallic middlings with the purpose of the maximal recovery of copper and zinc into the solution are performed. Using methods of mathematical planning of the experiment, the optimal process parameters are determined: ratio L: S = 5, the consumption of nitric acid is 80 cm3 per 20 g of the charge, and the process duration is 120 min. © 2013 Allerton Press, Inc.

  19. Sorption and leaching potential of acidic herbicides in Brazilian soils.

    Science.gov (United States)

    Spadotto, Claudio A; Hornsby, Arthur G; Gomes, Marco A F

    2005-01-01

    Leaching of acidic herbicides (2,4-D, flumetsulam, and sulfentrazone) in soils was estimated by comparing the original and modified AF (Attenuation Factor) models for multi-layered soils (AFi). The original AFi model was modified to include the concept of pH-dependence for Kd (sorption coefficient) based on pesticide dissociation and changes in the accessibility of soil organic functional groups able to interact with the pesticide. The original and modified models, considering soil and herbicide properties, were applied to assess the leaching potential of selected herbicides in three Brazilian soils. The pH-dependent Kd values estimated for all three herbicides were observed to be always higher than pH-independent Kd values calculated using average Koc data, and therefore the original AFi model overestimated the overall leaching potential for the soils studied. PMID:15656159

  20. Pb(II leaching from waste CRT funnel glass in nitric acid solutions

    Directory of Open Access Journals (Sweden)

    A. Strzałkowska

    2012-12-01

    Full Text Available Purpose: The paper presents experimental results of Pb (II leaching from waste CRT funnel glass using solution of nitric acid (V . This work focused on examining the impact of concentration and particle size on the leaching percentage of Pb (II from funnel glass.Design/methodology/approach: Material for the investigation was crushed and sieved. Leaching was carried out using working solutions pfrom co repared ncentrated HNO3 and mechanical stirrer.Findings: The received results show the possibility of find the parameters of leaching that could remove the whole Pb(II from funnel glass.Practical implications: Results after additional research can be applicate by glass industry.Originality/value: Worked out technologies can be used in glass recycling and production.

  1. The treatments of soil Rirang by floatation and Acid leaching

    International Nuclear Information System (INIS)

    The treatments of soil Rirang by floatation and acid leaching has been carried out to increase high uranium concentrates of materials, separating associated economical minerals and to reduce the gangue minerals which bothering at chemical processing. The physical treatment has been done by ore preparation and floatation using oleic acid and pine oil, 20 % of pulp at pH 9, condition time at 5 minutes and collections of float fraction was 10 minutes. The chemical processing has been done by dynamic leaching using H2SO4 100 kg/ton, MnO2 20 kg/ton, 50 % of solid with ore size - 65 mesh, temperature at 80 oC and time of leaching was 8 hours. The result of experiments is as follows : Physical treatment by floatation shown that the concentrates of U increased at sink fraction by (1.5 - 2) times against feed sample for all the samples, and in the float fraction the recovery of molybdenite separation is 58 - 81 % and rare earths is 57 - 80 %. The result of dynamic leaching is 76 - 91 %, and recovery uranium increasing from 81.02 % (mixture samples soil before floatation) to 91.16 % ( mixture samples of float fraction)

  2. Effect of Microwave Heating on the Leaching of Lateritic Nickel Ore in Perchloric Acid

    International Nuclear Information System (INIS)

    In this study, the leaching conditions of Sivrihisar (Adatepe) limonite type lateritic ore in acidic medium were investigated. Leaching experiments were carried out using conventional and microwave-assisted method. The effects of stirring speed, leaching temperature, perchloric acid concentration, solid/liquid ratio and particle size on conventional leaching were determined. Microwave-assisted leaching was carried out by using the optimum results of the conventional leaching. The pre-heating process was applied on different microwave powers (0, 90, 180, 360 and 600 W) and pre-processing time (0, 1, 3, 5, 7, 10, 15 and 20 min). These experimental results demonstrated that acid leaching was a convenient method for Ni extraction from lateritic ore. The higher dissolution and the higher Ni recoveries in the microwave-assisted leaching process were obtained in less leach time. (author)

  3. Primary beneficiation of tantalite using magnetic separation and acid leaching

    Institute of Scientific and Technical Information of China (English)

    M Nete; F Koko; T Theron; W Purcell; JT Nel

    2014-01-01

    Primary beneficiation was successfully performed prior to dissolution of manganotantalite (sample A) and ferrotantalite (sample C) samples obtained from two different mines in the Naquissupa area, Mozambique. Magnetic separation removed the majority of iron and tita-nium, whereas H2SO4 leaching removed a large portion of thorium and uranium in these samples. Analytical results indicated that 64.14wt%and 72.04wt%of the total Fe and Ti, respectively, and~2wt%each of Nb2O5 and Ta2O5 were removed from sample C (ferrotantalite) using the magnetic separation method, whereas only 9.64wt%and 8.66wt%of total Fe2O3 and TiO2, respectively, and~2wt%each of Nb2O5 and Ta2O5 were removed from sample A (manganotantalite). A temperature of 50°C and a leaching time of 3 h in the presence of concentrated H2SO4 were observed to be the most appropriate leaching conditions for removal of radioactive elements from the tantalite ores. The results obtained for sample A under these conditions indicated that 64.14wt%U3O8 and 60.77wt%ThO2 were leached into the acidic solution, along with 4.45wt%and 0.99wt%of Nb2O5 and Ta2O5, respectively.

  4. The presentation of leaching and bio-leaching from different ores using SIMPLEX EVOP

    OpenAIRE

    Krstev, Boris; Krstev, Aleksandar; Golomeova, Mirjana; Gocev, Zivko

    2013-01-01

    The refractory or low grade lead/zinc domestic ores in Republic of Macedonia are investigated by conventional separation technology or flotation separation. In the mean time, investigations are directed to the new possibilities of leaching by microorganisms – bioleaching. The paper is result of these technologies and investigations carried out for recovery of in the mentioned ores. Using Simplex EVOP and computer program Multisimplex performances are appropriate and most acceptable and exce...

  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. Method of gradual acid leaching of uranium ores of silicate and aluminosilicate nature

    International Nuclear Information System (INIS)

    Leaching uranium ore pulp is divided into two stages. The first stage takes place without any addition of a leaching agent at elevated pressure and temperature. In the second stage, sulfuric acid is added to the pulp (50 to 1000 kg per tonne of ore) or an oxidation agent. Leaching then proceeds according to routine procedures. The procedure is used to advantage for silicate or aluminosilicate ores which contain uranium minerals which are difficult to leach, pyrite and reducing substances. The two stage leaching allows to use the technology of pressure leaching, reduces consumption of sulfuric acid and oxidation agents and still achieves the required reduction oxidation potential. (E.S.)

  7. 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.

  8. Leaching of Carbothermic Reduced Titanium-bearing Blast Furnace Slag by Acid

    Institute of Scientific and Technical Information of China (English)

    ZHEN Yulan; ZHANG Guohua; CHOU Kuochih

    2016-01-01

    The kinetics of the leaching of carbothermic reduced titanium-bearing blast furnace slag in Panzhihua Iron and Steel Company with acid system under atmosphere pressure was studied. The results show that the temperature and concentration have significant influence on leaching of carbothermic reduced titanium-bearing blast furnace slag by ac-id. The experimental data of leaching indicate that the shrinking core model with chemical reaction controlled process is most applicable for the acid leaching. The apparent activation energy can be estimated to be from 23 to 32 kJ/mol. Fur-thermore, the main products are TiC and SiO2 after leaching.

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

    International Nuclear Information System (INIS)

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    1999-11-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    1999-01-01

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

  12. Dissolution behavior of Caldag lateritic nickel ore subjected to a sequential organic acid leaching method

    Science.gov (United States)

    Kursunoglu, Sait; Kaya, Muammer

    2015-11-01

    The dissolution behavior of Caldag lateritic nickel ore subjected to a sequential organic acid leaching method was investigated. The effects of the type of organic acid, acid concentration, leaching time, and leaching temperature on the lateritic nickel ore were examined. Organic acids were used individually prior to sequential leaching. Citric acid was more effective than the other two acids for the selective leaching of nickel and cobalt. An increase in the citric acid concentration negligibly affected the dissolution of the metals, whereas temperature exhibited a strong beneficial effect. Oxalic acid was determined to be the most appropriate organic acid for the second leaching step. After 8 h (4 h + 4 h) of leaching with organic acids (0.5 M citric + 0.5 M oxalic) in sequence at 90°C, 89.63% Ni, 82.89% Co, and 69.63% Fe were leached from the lateritic nickel ore. A sequential citric + oxalic acid leaching method could represent a viable alternative for the dissolution of metals from lateritic nickel ore.

  13. Leaching of spent lead acid battery paste components by sodium citrate and acetic acid.

    Science.gov (United States)

    Zhu, Xinfeng; He, Xiong; Yang, Jiakuan; Gao, Linxia; Liu, Jianwen; Yang, Danni; Sun, Xiaojuan; Zhang, Wei; Wang, Qin; Kumar, R Vasant

    2013-04-15

    A sustainable method, with minimal pollution and low energy cost in comparison with the conventional smelting methods, is proposed for treating components of spent lead-acid battery pastes in aqueous organic acid(s). In this study, PbO, PbO2, and PbSO4, the three major components in a spent lead paste, were individually reacted with a mixture of aqueous sodium citrate and acetic acid solution. Pure lead citrate precursor of Pb3(C6H5O7)2 · 3H2O is the only product crystallized in each leaching experiment. Conditions were optimized for individual lead compounds which were then used as the basis for leaching real industrial spent paste. In this work, efficient leaching process is achieved and raw material cost is reduced by using aqueous sodium citrate and acetic acid, instead of aqueous sodium citrate and citric acid as reported in a pioneering hydrometallurgical method earlier. Acetic acid is not only cheaper than citric acid but is also more effective in aiding dissolution of the lead compounds thus speeding up the leaching process in comparison with citric acid. Lead citrate is readily crystallized from the aqueous solution due to its low solubility and can be combusted to directly produce leady oxide as a precursor for making new battery pastes.

  14. Chapter 4. Uranium extraction technology from wastes of uranium industry. 4.1. Sulfuric acid leaching kinetics of residues from anthropogenic deposit Map 1-9

    International Nuclear Information System (INIS)

    Present article is devoted to sulfuric acid leaching kinetics of residues from anthropogenic deposit Map 1-9. Since residues from anthropogenic deposit Map 1-9 basically contain quartz (69%), it went through acid leaching. Results of laboratory investigations on the opening degree and uranium conversion to solution were summarized. The influence of sulfuric acid consumption on uranium extraction during leaching (U = 0,018%, t =20 deg C, t = 10 hours) was considered. The kinetic and energetic parameters of residues leaching of anthropogenic deposit Map 1-9 was discussed. The basic process flow diagram of uranium industry wastes reprocessing was proposed.

  15. Leaching of vanadium from stone coal with sulfuric acid

    Institute of Scientific and Technical Information of China (English)

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

    2009-01-01

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

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

    Science.gov (United States)

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

    2016-05-01

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

  17. Selective Acidic Leaching of Spent Zinc-Carbon Batteries Followed by Zinc Electrowinning

    Science.gov (United States)

    Shalchian, Hossein; Rafsanjani-Abbasi, Ali; Vahdati-Khaki, Jalil; Babakhani, Abolfazl

    2015-02-01

    In this work, a selective acidic leaching procedure was employed for recycling zinc from spent zinc-carbon batteries. Leaching experiments were carried out in order to maximize zinc recovery and minimize manganese recovery in diluted sulfuric acid media. Response surface methodology and analysis of variance were employed for experimental design, data analysis, and leaching optimization. The experimental design has 28 experiments that include 24 main runs and four replicate in center point. The optimal conditions obtained from the selective acidic leaching experiments, were sulfuric acid concentration of 1 pct v/v, leaching temperature of 343 K (70 °C), pulp density of 8 pct w/v, and stirring speed of 300 rpm. The results show that the zinc and manganese recoveries after staged selective leaching are about 92 and 15 pct, respectively. Finally, metallic zinc with purity of 99.9 pct and electrolytic manganese dioxide were obtained by electrowinning.

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

    OpenAIRE

    Sokić M.; Marković B.; Matković V.; Živković D.; Štrbac N.; Stojanović J.

    2012-01-01

    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 ...

  19. Concentrating Ge in zinc hydrometallurgical process with hot acid leaching-halotrichite method

    Institute of Scientific and Technical Information of China (English)

    何静; 唐谟堂; 鲁君乐; 刘中清; 杨声海; 姚维义

    2003-01-01

    In recovering Ge and Ag from the calcine and fume dusts mixture of Huidong Lead-zinc Mine, the flow sheet of hot acid leaching-halotrichite method mainly consists of neutral leaching, low-acid leaching, high acid leaching and jarosite precipitation. In the ten circulation periods, the technology flow sheet was carried out smoothly.The loss of Ge in halotrichite residue is less than 5.0%, when iron is precipitated by using ferric potassium alum instead of common Na or ammonium alum and the conditions are controlled at temperature about 95 ℃ for more than 3 h, pH values below 1.5. Ge and Ag are concentrated in the high acid leached residue, and their contents are 0. 032% and 0. 162%, respectively, and the total recovery and direct recovery of zinc are 98.94% and 96.15%, respectively.

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

    Institute of Scientific and Technical Information of China (English)

    李来时; 吴玉胜; 刘瑛瑛; 翟玉春

    2011-01-01

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

  1. Study on the Leaching of Pt, Pd and Rh from Spent Auto-catalysts in Various Acidities

    Institute of Scientific and Technical Information of China (English)

    WAN Jing; YU Jianmin; QIAN Lin; WAN Huoyin; ZHAO Yunkun

    2012-01-01

    Auto-catalysts were the largest consumers of platinum group metals and the most important secondary resources,recovery of PGMs from spent auto-catalysts by leaching with various acidities were investigated.The leaching thermodynamics of PGMs at 363 K was first discussed.At 363 K the higher the acidities of HC1,the higher the leaching recoveries of PGMs,and the sequence of leaching recovery was Pd>Pt>Rh.When H2SO4 used alone,the leaching recoveries of PGMs was low,when the acidity of H2SO4 increasing,the leaching recovery of Rh kept stable.

  2. Hydrometallurgical process for zinc recovery from electric arc furnace dust (EAFD): part I: Characterization and leaching by diluted sulphuric acid.

    Science.gov (United States)

    Oustadakis, P; Tsakiridis, P E; Katsiapi, A; Agatzini-Leonardou, S

    2010-07-15

    The present paper is the first of a series of two articles dealing with the development of an integrated process for the recovery of zinc from electric arc furnace dust (EAFD), a hazardous industrial waste generated in the collection of particulate material during steelmaking process via electric arc furnace. Part I presents the EAFD characterization and its leaching process by diluted sulphuric acid, whereas Part II deals with the purification of the leach liquor and the recovery of zinc by solvent extraction/electrowinning. The characterization of the examined electric arc furnace dust was carried out by using granulometry analysis, chemical analysis, X-ray diffraction (XRD), thermogravimetric/differential thermal analysis (TG/DTA) and scanning electron microscopy (SEM). The leaching process was based on the Zn extraction with diluted sulphuric acid from EAFD under atmospheric conditions and without using any preliminary treatment. Statistical design and analysis of experiments were used, in order to determine the main effects and interactions of the leaching process factors, which were: acid normality, temperature and solid to liquid ratio. The zinc recovery efficiency on the basis of EAFD weight reached 80%. X-ray diffraction and scanning electron microscopy were used for the characterization of the leached residues.

  3. 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.

  4. Extraction of uranium from coarse ore and acid-curing and ferric sulphate-trickle leaching process

    International Nuclear Information System (INIS)

    On the basis of analysis of the problems in the technology of the traditional uranium hydrometallurgy and the limitations of thin layer leaching process (TLL), a new leaching system-acid-curing and ferric sulphate-trickle leaching (AFL) process (NGJ in Chinese) has developed for extraction of uranium from the coarse ore. The ferric sulphate solution was used for trickling the acid-cured uranium ore and the residual leaching reaction incomplete in TLL process can be improved in this process. And the AFL process has a wide applicability to China's uranium ores, being in competition with the traditional agitation leaching process for treating coarse ores. The uranium ore processing technology based on the AFL process will become one of the new basic technologies of uranium hydrometallurgy. A series of difficulties will be basically overcome associated with fine grinding because of its elimination in the presented process. Moreover, the situation of the present uranium hydrometallurgy can be also changed owing to without technological effluent discharge

  5. Soil stabilisation using AMD sludge, compost and lignite: TCLP leachability and continuous acid leaching.

    Science.gov (United States)

    Tsang, Daniel C W; Olds, William E; Weber, Paul A; Yip, Alex C K

    2013-11-01

    Utilising locally available industrial by-products for in situ metal stabilisation presents a low-cost remediation approach for contaminated soil. This study explored the potential use of inorganic (acid mine drainage (AMD) sludge and zero-valent iron) and carbonaceous materials (green waste compost, manure compost, and lignite) for minimising the environmental risks of As and Cu at a timber treatment site. After 9-month soil incubation, significant sequestration of As and Cu in soil solution was accomplished by AMD sludge, on which adsorption and co-precipitation could take place. The efficacy of AMD sludge was comparable to that of zero-valent iron. There was marginal benefit of adding carbonaceous materials. However, in a moderately aggressive environment (Toxicity Characteristic Leaching Procedure), AMD sludge only suppressed the leachability of As but not Cu. Therefore, the provision of compost and lignite augmented the simultaneous reduction of Cu leachability, probably via surface complexation with oxygen-containing functional groups. Under continuous acid leaching in column experiments, combined application of AMD sludge with compost proved more effective than AMD sludge with lignite. This was possibly attributed to the larger amount of dissolved organic matter with aromatic moieties from lignite, which may enhance Cu and As mobility. Nevertheless, care should be taken to mitigate ecological impact associated with short-term substantial Ca release and continuous release of Al at a moderate level under acid leaching. This study also articulated the engineering implications and provided recommendations for field deployment, material processing, and assessment framework to ensure an environmentally sound application of reactive materials. PMID:24144464

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

    DEFF Research Database (Denmark)

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

    2014-01-01

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

  7. Reductive Leaching Kinetics of Low Grade Manganese Deposits in H2SO4 Solution Using Malonic Acid as Reducing Agent

    OpenAIRE

    Taysser Lasheen; S. A. Abu Elenein; Saleh, W A; A. H Orabi; D. A Ismaiel

    2014-01-01

    A leaching process was developed to extract manganese and metal values from Alloga manganese concentrate. The preferential leaching process was achieved through reductive leaching in dilute sulfuric acid medium with malonic acid as the reducing agent. Leaching parameters were optimized as 1.0 M H2SO4, 10% malonic acid in solid/liquid ratio 1:10 for 90 min at 80 C and using ore ground to – 74 µm. Under these conditions, the leaching efficiency of manganese reaches 97%, whilst iron dissolution ...

  8. Kinetics of Reductive Acid Leaching of Cadmium-Bearing Zinc Ferrite Mixture Using Hydrazine Sulfate

    Science.gov (United States)

    Zhang, Chun; Zhang, Jianqiang; Min, Xiaobo; Wang, Mi; Zhou, Bosheng; Shen, Chen

    2015-09-01

    The reductive acid leaching kinetics of synthetic cadmium-bearing zinc ferrite was investigated, and the influence of reaction temperature, sulfuric acid and hydrazine sulfate were studied. The results illustrated that an increase in the reaction temperature, initial sulfuric acid and hydrazine sulfate significantly enhanced the extraction efficiencies of cadmium, zinc and iron. The leaching kinetics were controlled by a surface chemical reaction based on a shrinking core model. The empirical equation applied was found to fit well with the kinetics analysis; the leaching processes of cadmium, zinc and iron were similar and the activation energies were 79.9 kJ/mol, 77.9 kJ/mol and 79.7 kJ/mol, respectively. The apparent orders of cadmium-bearing zinc ferrite dissolution with respect to sulfuric acid concentration were 0.83, 0.83 and 0.84 for Cd, Zn and Fe, respectively.

  9. Process optimization of reaction of acid leaching residue of asbestos tailing and sodium hydroxide aqueous solution

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    Silica is the major component of the acid leaching residue of asbestos tailing. The waterglass solution can be prepared by the reaction of the residue with sodium hydroxide aqueous solution. Compared to the high temperature reaction method, this process is environmental friendly and low cost. In this paper, the reaction process of the residue and the sodium hydroxide aqueous solution is optimized. The optimum reaction process parameters are as follows: the usage of sodium hydroxide is 26.4 g/100 g acid leaching residue, the reaction temperature is 90℃, the reaction time is 1 h, and the ratio of the liquid/solid is 2.0. The significance sequence of the process parameters to the alkali leaching reaction effect is the usage of sodium hydroxide > the ratio of the liquid/solid > the reaction time > the reaction temperature. The significance sequence to the leaching ratio of SiO2 is the ratio of the liquid/solid > the usage of sodium hydroxide > the reaction time > the reaction temperature. The significance sequence to the modulus of the sodium silicate is the ratio of the liquid/solid > the usage of sodium hydroxide > the reaction time > the reaction temperature. Under the optimum conditions, the leaching ratio of the SiO2 is 77.5%, and the modulus of the sodium silicate is 3.15. The XRD analysis result indicates that the major components of the alkali leaching residue are serpentine, talc, quartz and some albite.

  10. Influences of humic acid and fulvic acid on horizontal leaching behavior of anthracene in soil barriers.

    Science.gov (United States)

    Yu, Sheng; Li, Bang-Yu; Chen, Yi-Hu

    2015-12-01

    The influences of humic acid (HA) and fulvic acid (FA) on horizontal leaching behaviors of anthracene in barriers were investigated. Soil colloids (≤1 μm) were of concern because of their abilities of colloid-facilitated transport for hydrophobic organic compounds with soluble and insoluble organic matters. Through freely out of the barriers in the presence of soil colloids with FA added, the higher concentrations of anthracene were from 320 μg L(-1) (D1 and D3) to 390 μg L(-1) (D2 and D4) with 1 to 20 cm in length. The contents of anthracene were distributed evenly at 25 ng g(-1) dry weight (DW) (D1 and D3) and 11 ng g(-1) DW (D2 and D4) in barriers. Therefore, anthracene leaching behaviors were mainly induced by soil colloids with soluble organic matters. The insoluble organic matters would facilitate anthracene onto soil colloids and enhance the movement in and through porous media of soil matrix. PMID:26300357

  11. Meteoric 10Be in volcanic materials and its behavior during acid-leaching

    Science.gov (United States)

    Shimaoka, Akiko; Sakamoto, Minoru; Hiyagon, Hajime; Matsuzaki, Hiroyuki; Kaneoka, Ichiro; Imamura, Mineo

    2004-08-01

    We have investigated the chemical and isotopic behavior of beryllium (Be) during acid leaching for removing meteoric 10Be in volcanic samples. Determination of the Be isotopic ratio in the leachate was carried out using accelerator mass spectrometry (AMS) and inductivity coupled plasma mass spectrometer (ICP-MS). Elemental distribution of Be and other incompatible elements including boron (B) were also examined by ion microprobe (SIMS) for a deeper understanding of their chemical behavior in volcanic samples. SIMS analysis show that Be is concentrated in the groundmass together with B. However, the behavior of their elements during acid leaching is quite different. The Be concentration decreases through progressive leaching, while the concentration of B remains constant. Furthermore, the variation in the Be isotopic ratio after acid leaching is different between the two samples, neither of which has altered minerals under microscopic observation. It is demonstrated that meteoric 10Be resides in a rather narrow region of the rock and can be removed by acid leaching with minimum loss of the main host phase of Be.

  12. An Approach to Reduce Load on the Acid Leaching Circuit of the Commercial Uranium Recovery Plant at Jaduguda, India

    OpenAIRE

    Rao, G. V.; Prakash, S.

    1998-01-01

    The commercial uranium recovery plant at Jaduguda, Bihar, India, currently treats around 900 tonnes of ore per day from the Jaduguda mine, containing around 0.05% U3O8. Subsequent to removal of the sulphide minerals present in the ore by flotation, nearly 95% of the tailings are being treated in the acid leaching circuit to recover the uranium values. Laboratory investigations on the bulk flotation tailings revealed that around 63% of the uranium values are associated with feebly magnetic mat...

  13. Leaching and selective copper recovery from acidic leachates of Três Marias zinc plant (MG, Brazil) metallurgical purification residues.

    Science.gov (United States)

    Sethurajan, Manivannan; Huguenot, David; Lens, Piet N L; Horn, Heinrich A; Figueiredo, Luiz H A; van Hullebusch, Eric D

    2016-07-15

    Zinc plant purification residue (ZPR), a typical Zn-hydrometallurgical waste, was collected from the Três Marias Zn plant (MG, Brazil). ZPR was characterized for its metal content and fractionation, mineralogy, toxicity and leachability. Toxicity characteristics leaching procedure (TCLP) and European Community Bureau of Reference (BCR) sequential extraction results revealed that this ZPR displays high percentages of metals (Cd, Cu, Zn and Pb) in the highly mobilizable fractions, increasing its hazardous potential. Bulk chemical analysis, pH dependent leaching and acid (H2SO4) leaching studies confirm that the ZPR is polymetallic, rich in Cd, Cu and Zn. The sulfuric acid concentration (1 M), agitation speed (450 rpm), temperature (40 °C) and pulp density (20 g L(-1)) were optimized to leach the maximum amount of heavy metals (Cd, Cu and Zn). Under optimum conditions, more than 50%, 70% and 60% of the total Cd, Cu and Zn present in the ZPR can be leached, respectively. The metals in the acid leachates were investigated for metal sulfide precipitation with an emphasis on selective Cu recovery. Metal sulfide precipitation process parameters such as initial pH and Cu to sulfide ratio were optimized as pH 1.5 and 1:0.5 (Cu:sulfide) mass ratio, respectively. Under optimum conditions, more than 95% of Cu can be selectively recovered from the polymetallic ZPR leachates. The Cu precipitates characterization studies reveal that they are approximately 0.1 μm in diameter and mainly consist of Cu and S. XRD analysis showed covellite (CuS), chalcanthite (CuSO4·5H2O) and natrochalcite (NaCu2(SO4)2(OH)·H2O) as the mineral phases. ZPRs can thus be considered as an alternative resource for copper production. PMID:27074201

  14. Site susceptibility to leaching by H/sub 2/SO/sub 4/ in acid rainfall

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, D. W.

    1978-01-01

    One of the major concerns about the terrestrial effects of acid rainfall has been the leaching of nutrient cations from forest soils and the consequences of this to forest growth. A concept that has proven useful in assessing soil leaching due to acid rainfall and many other manipulations is that of anion mobility in the soil. This concept does not consider cation exchange reactions directly, but the sum of cations must balance the sum of anions, in meq/l, in the soil solution. Total ionic leaching can, therefore, be described by anion flux alone. Although much more basic research has been devoted to cation adsorption and exchange than to anion adsorption and exchange, the anion mobility concept has proven very valuable in explaining soil leaching processes in both undisturbed and disturbed conditions. The effects of atmospheric sulfuric acid inputs on forest soil leaching have been evaluated from the perspective of the mobility of the sulfate anion in several ecosystems. In this paper, the factors affecting sulfate mobility in soils are discussed in relation to soil properties and site susceptibility, drawing some examples from specific studies.

  15. Ag recovery from copper anode slime by acid leaching at atmospheric pressure to synthesize silver nanoparticles

    Institute of Scientific and Technical Information of China (English)

    Atefeh Khaleghi; Sattar Ghader; Dariush Afzali

    2014-01-01

    In this paper, recovery of silver from anode slime of Sarcheshmeh copper complex in Iran and subsequent synthesis of silver nanoparticles from leaching solution is investigated. Sarcheshmeh anode slime is mainly consisted of Cu, Ag, Pb and Se. Amount of Ag in the considered anode slime was 5.4%(by weight). The goal was to recover as much as possible Ag from anode slime at atmospheric pressure to synthesize Ag nanoparticles. Therefore, acid leaching was used for this purpose. The anode slime was leached with sulfuric and nitric acid from room to 90 ?C at different acid concentrations and the run which yielded the most recovery of Ag was selected for Ag nanoparticles synthesis. At this condition, Cu, Pb and Se are lea-ched as well as Ag. To separate Ag from leach solution HCl was added and silver was precipitated as AgCl which were then dissolved by ammonia solution. The Ag nanoparticles are synthesized from this solution by chemical reduction method by aid of sodium borohydride in the presence of PVP and PEG as stabiliz-ers. The synthesized Ag nanoparticles showed a peak of 394 nm in UV-vis spectrum and TEM images showed a rather uniform Ag nanoparticles of 12 nm.

  16. Leaching potential and changes in components of metals in two acidic ferrisols

    Institute of Scientific and Technical Information of China (English)

    GUO Zhao-hui; LIAO Bo-han; HUANG Chang-yong

    2006-01-01

    Two acidic ferrisols, i.e., red soil (RS) and yellow red soil (YRS), from the vicinity regions of non-ferrous ores in Hunan province of China, were leached with simulated acid rain through artificial column experiments. The results show that the total leaching mass of metals are m(Zn)>m(Cu)>m(Cd) from the original soils and m(Cd)>m(Zn)>> m(Cu) from the contaminated soils with external metals after leaching for 60 d continuously, leaching quantities of Cd and Zn from the contaminated red soil (CRS)are more than that from the contaminated yellow red soil (CYRS), but for Cu, it is almost the same. The preferential fractions for leaching are mainly in exchangeable forms, and content of exchangeable forms decreases significantly in the contaminated soil profiles. The unstable fractions of Cd, Cu and Zn in the RS and YRS increase significantly with the decrease of pH value of simulated acid rain. Changes of fractions of external Cd, Cu, and Zn in the residual CRS and CYRS profiles are significantly affected by the acidity of acid rain, too. After leaching for 60 d continuously, Cd exists mostly in exchangeable form, Cu exists mainly in exchangeable, manganese oxide-occluded and organically bounding forms, and Zn exists in residual in CRS and CYRS profiles.Most of exchangeable Cd and Zn exist only small in surface layer (0-20 cm) and are transferred to the sub-layers, contrarily, Cu accumulates mostly in the topsoil (0-20 cm) with low translocation.

  17. Acid decomposition and thiourea leaching of silver from hazardous jarosite residues: Effect of some cations on the stability of the thiourea system.

    Science.gov (United States)

    Calla-Choque, D; Nava-Alonso, F; Fuentes-Aceituno, J C

    2016-11-01

    The recovery of silver from hazardous jarosite residues was studied employing thiourea as leaching agent at acid pH and 90°C. The stability of the thiourea in synthetic solutions was evaluated in the presence of some cations that can be present in this leaching system: cupric and ferric ions as oxidant species, and zinc, lead and iron as divalent ions. Two silver leaching methods were studied: the simultaneous jarosite decomposition-silver leaching, and the jarosite decomposition followed by the silver leaching. The study with synthetic solutions demonstrated that cupric and ferric ions have a negative effect on thiourea stability due to their oxidant properties. The effect of cupric ions is more significant than the effect of ferric ions; other studied cations (Fe(2+), Zn(2+), Pb(2+)) had no effect on the stability of thiourea. When the decomposition of jarosite and the silver leaching are carried out simultaneously, 70% of the silver can be recovered. When the acid decomposition was performed at pH 0.5 followed by the leaching step at pH 1, total silver recovery increased up to 90%. The zinc is completely dissolved with any of these processes while the lead is practically insoluble with these systems producing a lead-rich residue. PMID:27322901

  18. Uranium Leaching from Contaminated Soil Utilizing Rhamnolipid, EDTA, and Citric Acid

    Directory of Open Access Journals (Sweden)

    Sara Asselin

    2014-01-01

    Full Text Available Biosurfactants have recently gained attention as “green” agents that can be used to enhance the remediation of heavy metals and some organic matter in contaminated soils. The overall objective of this paper was to investigate rhamnolipid, a microbial produced biosurfactant, and its ability to leach uranium present in contaminated soil from an abandoned mine site. Soil samples were collected from two locations in northern Arizona: Cameron (site of open pit mining and Leupp (control—no mining. The approach taken was to first determine the total uranium content in each soil using a hydrofluoric acid digestion, then comparing the amount of metal removed by rhamnolipid to other chelating agents EDTA and citric acid, and finally determining the amount of soluble metal in the soil matrix using a sequential extraction. Results suggested a complex system for metal removal from soil utilizing rhamnolipid. It was determined that rhamnolipid at a concentration of 150 μM was as effective as EDTA but not as effective as citric acid for the removal of soluble uranium. However, the rhamnolipid was only slightly better at removing uranium from the mining soil compared to a purified water control. Overall, this study demonstrated that rhamnolipid ability to remove uranium from contaminated soil is comparable to EDTA and to a lesser extent citric acid, but, for the soils investigated, it is not significantly better than a simple water wash.

  19. The effect of organic acids on base cation leaching from the forest floor under six North American tree species

    NARCIS (Netherlands)

    Dijkstra, F.A.; Geibe, C.; Holmstrom, S.; Lundstrom, U.S.; Breemen, van N.

    2001-01-01

    Organic acidity and its degree of neutralization in the forest floor can have large consequences for base cation leaching under different tree species. We investigated the effect of organic acids on base cation leaching from the forest floor under six common North American tree species. Forest floor

  20. Leaching Behavior and Mechanism of Cement Solidiifed Heavy Metal Pb in Acid Medium

    Institute of Scientific and Technical Information of China (English)

    ZHOU Mingkai; WANG Caiping; CHEN Yan; CHEN Xiao

    2015-01-01

    The relationship between Pb leaching concentration and the solution’s pH with time was analyzed when cement in its solidiifed form was leached in an acid medium. The effects of the particle size of the solidified form, the cement adding method, and the hydration degree on Pb solidification were also investigated. The experimental results indicate that cement is quickly dissolved and hydrated in the acid medium, forming a C-S-H gel or silicic acid sol with good adsorption. When cement-Pb solidified form is leached in an acetate solution, the hydrated product erodes with time, so the Pb concentration increases slightly in the beginning. Then, some of the Pb ions are absorbed by the newly generated silicic acid sol, C-S-H. Others produce Pb(OH)2 precipitation for secondary solidification, leading to a gradual decrease in the Pb concentration in a leaching time of more than two hours. Moreover, the particle size of the solidiifed form has important effects on the Pb dissolution. When the amount of added cement is low, with a pH of less than 9.5, the solidiifcation affects the sequence of the original cement powder, the cement hydrated powder, and the cement-Pb solidiifed form. When the added amount of cement increases with a pH of more than 11, the effect of adding methods on solidiifcation decreases, and the solidiifed form is a little better than others.

  1. Use of organosmectites to reduce leaching losses of acidic herbicides

    OpenAIRE

    Carrizosa, M. J.; Hermosín, M. C.; Koskinen, W. C.; Cornejo, J.

    2003-01-01

    The modification of smectitic clays with organic cations via cation-exchange reactions produces sorbents with an increased sorption capacity for organic compounds such as acidic herbicides. These organoclays (OCIs) could be used as carriers in controlled release formulations of herbicides to decrease their contamination potential. Various OCIs and two acidic herbicides (bentazone [3-isopropyl-1H-2,1,3-benzothiadiazin-4 (3H) one 2,2-dioxide] and dicamba [2-methoxy-3,6-dichlorobenzoic acid]) we...

  2. Reducing acid leaching of manganiferous ore: Effect of the iron removal operation on solid waste disposal

    International Nuclear Information System (INIS)

    The process of reducing acid leaching of manganiferous ore is aimed at the extraction of manganese from low grade manganese ores. This work is focused on the iron removal operation. The following items have been considered in order to investigate the effect of the main operating conditions on solid waste disposal and on the process costs: (i) type and quantity of the base agent used for iron precipitation, (ii) effective need of leaching waste separation prior to the iron removal operation, (iii) presence of a second leaching stage with the roasted ore, which might also act as a preliminary iron removal step, and (iv) effect of tailings washing on the solid waste classification. Different base compounds have been tested, including CaO, CaCO3, NaOH, and Na2CO3. The latter gave the best results concerning both the precipitation process kinetics and the reagent consumption. The filtration of the liquor leach prior to iron removal was not necessary, implying significant savings in capital costs. A reduction of chemical consumption and an increase of manganese concentration in the solution were obtained by introducing secondary leaching tests with the previously roasted ore; this additional step was introduced without a significant decrease of global manganese extraction yield. Finally, toxicity characteristic leaching procedure (TCLP) tests carried out on the leaching solid waste showed: (i) a reduction of arsenic mobility in the presence of iron precipitates, and (ii) the need for a washing step in order to produce a waste that is classifiable as not dangerous, taking into consideration the existing Environmental National Laws

  3. Decontamination of CCA-treated eucalyptus wood waste by acid leaching.

    Science.gov (United States)

    Ferrarini, Suzana Frighetto; dos Santos, Heldiane Souza; Miranda, Luciana Gampert; Azevedo, Carla Maria Nunes; Maia, Sandra Maria; Pires, Marçal

    2016-03-01

    Preservatives such as chromated copper arsenate (CCA) are used to increase the resistance of wood to deterioration. The components of CCA are highly toxic, resulting in growing concern over the disposal of the waste generated. The aim of this study was to investigate the removal of Cu, Cr and As present in CCA-treated eucalyptus wood from utility poles removed from service in southern Brazil, in order to render them non-hazardous waste. The removal was carried out by acid leaching in bench-scale and applying optimal extractor concentration, total solid content, reactor volume, temperature and reaction time obtained by factorial experiments. The best working conditions were achieved using three extraction steps with 0.1 mol L(-1) H2SO4 at 75°C for 2h each (total solid content of 15%), and 3 additional 1h-long washing steps using water at ambient temperature. Under these conditions, removal of 97%, 85% and 98% were obtained for Cu, Cr and As, respectively, rendering the decontaminated wood non-hazardous waste. The wastewater produced by extraction showed acid pH, high organic loading as well as high concentrations of the elements, needing prior treatment to be discarded. However, rinsing water can be recycled in the extraction process without compromising its efficiency. The acid extraction is a promising alternative for CCA removal from eucalyptus wood waste in industrial scale. PMID:26856447

  4. Recovery of zinc and manganese from spent batteries by reductive leaching in acidic media

    Science.gov (United States)

    Buzatu, M.; Săceanu, S.; Petrescu, M. I.; Ghica, G. V.; Buzatu, T.

    2014-02-01

    A systematic investigation has been carried out on the influence of the acid leaching process parameters on the simultaneous metal recovery (Zn and Mn) from the electrode paste of spent alkaline Zn-MnO2 and spent Zn-C batteries. By introducing a reducing agent namely 30% H2O2 in the H2SO4 leaching solution the extraction efficiency for Mn was increased from 43.5% (no addition of H2O2) up to 97.54% (50% excess H2O2 in comparison with the required stoichiometric amount of H2O2). This H2O2 addition proved to have no influence on Zn extraction efficiency which kept constant at a high level (∼98.4%). A less important influence has been noticed for the molar concentration of H2SO4 in the leaching solution. In the range 0.5 M up to 2 M molar concentration of H2SO4 the extraction efficiency was increased from 78.2% up to 98.4% for Zn and from 63.1% up to 97.2% for Mn. Leaching time up to 60 min proved to gradually increase the extraction efficiency up to 96% for Mn and 98% for Zn but further time increase has no more influence. An attempt has been made to recover the carbon from the leaching residue but its structural characterization is still required.

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

    Science.gov (United States)

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

    2014-04-01

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

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

    Institute of Scientific and Technical Information of China (English)

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

    2014-01-01

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

  7. Process optimization of reaction of acid leaching residue of asbestos tailing and sodium hydroxide aqueous solution

    Institute of Scientific and Technical Information of China (English)

    DU GaoXiang; ZHENG ShuiLin; DING Hao

    2009-01-01

    Silica is the major component of the acid leaching residue of asbestos tailing. The waterglass solution can be prepared by the reaction of the residue with sodium hydroxide aqueous solution. Compared to the high temperature reaction method, this process is environmental friendly and low cost. In this paper, the reaction process of the residue and the sodium hydroxide aqueous solution is optimized. The op-timum reaction process parameters are as follows: the usage of sodium hydroxide is 26.4 g/100 g acid leaching residue, the reaction temperature is 90℃, the reaction time is 1 h, and the ratio of the liq-uid/solid is 2.0. The significance sequence of the process parameters to the alkali leaching reaction effect is the usage of sodium hydroxide > the ratio of the liquid/solid > the reaction time > the reaction temperature. The significance sequence to the leaching ratio of SiO2 is the ratio of the liquid/solid > the usage of sodium hydroxide > the reaction time > the reaction temperature. The significance sequence to the modulus of the sodium silicate is the ratio of the liquid/solid > the usage of sodium hydroxide > the reaction time > the reaction temperature. Under the optimum conditions, the leaching ratio of the SiO2 is 77.5%, and the modulus of the sodium silicate is 3.15. The XRD analysis result indicates that the major components of the alkali leaching residue are serpentine, talc, quartz and some albite.

  8. Effect of reduction in acid rain on phosphate loss-phosphate leached from agriculture soil and Al leaked from upstream acid forest soil

    OpenAIRE

    2012-01-01

    This master thesis was an integrated part of EUTROPIA. The specific aim of this present study is to enhance our understanding of the effects of reduction in acid rain on P-loss from agriculture soil due to reduced co-precipitation between P leached from agriculture soil and Al leaked from upstream acid forest soils. The study was carried out at two watersheds: Dalen, which is an aluminium rich, acidic forest stream water catchment upstream, and Støa1, which is a P-loaded agricultural water ca...

  9. Uranium, Cesium, and Mercury Leaching and Recovery from Cemented Radioactive Wastes in Sulfuric Acid and Iodide Media

    Directory of Open Access Journals (Sweden)

    Nicolas Reynier

    2015-11-01

    Full Text Available The Canadian Nuclear Laboratories (CNL is developing a long-term management strategy for its existing inventory of solid radioactive cemented wastes, which contain uranium, mercury, fission products, and a number of minor elements. The composition of the cemented radioactive waste poses significant impediments to the extraction and recovery of uranium using conventional technology. The goal of this research was to develop an innovative method for uranium, mercury and cesium recovery from surrogate radioactive cemented waste (SRCW. Leaching using sulfuric acid and saline media significantly improves the solubilization of the key elements from the SRCW. Increasing the NaCl concentration from 0.5 to 4 M increases the mercury solubilization from 82% to 96%. The sodium chloride forms a soluble mercury complex when mercury is present as HgO or metallic mercury but not with HgS that is found in 60 °C cured SRCW. Several leaching experiments were done using a sulfuric acid solution with KI to leach SRCW cured at 60 °C and/or aged for 30 months. Solubilization yields are above 97% for Cs and 98% for U and Hg. Leaching using sulfuric acid and KI improves the solubilization of Hg by oxidation of Hg0, as well as HgS, and form a mercury tetraiodide complex. Hg and Cs were selectively removed from the leachate prior to uranium recovery. It was found that U recovery from sulfuric leachate in iodide media using the resin Lewatit TP260 is very efficient. Considering these results, a process including effluent recirculation was applied. Improvements of solubilization due to the recycling of chemical reagents were observed during effluent recirculation.

  10. Different low-molecular-mass organic acids specifically control leaching of arsenic and lead from contaminated soil

    Science.gov (United States)

    Ash, Christopher; Tejnecký, Václav; Borůvka, Luboš; Drábek, Ondřej

    2016-04-01

    Low-molecular-mass organic acids (LMMOA) are of key importance for mobilisation and fate of metals in soil, by functioning as ligands that increase the amount of dissolved metal in solution or by dissociation of metal binding minerals. Column leaching experiments were performed on soil polluted with As and Pb, in order to determine the specificity of LMMOA related release for individual elements, at varying organic acid concentrations. Acetic, citric and oxalic acids were applied in 12 h leaching experiments over a concentration range (0.5-25 mM) to soil samples that represent organic and mineral horizons. The leaching of As followed the order: oxalic > citric > acetic acid in both soils. Arsenic leaching was attributed primarily to ligand-enhanced dissolution of mineral oxides followed by As released into solution, as shown by significant correlation between oxalic and citric acids and content of Al and Fe in leaching solutions. Results suggest that subsurface mineral soil layers are more vulnerable to As toxicity. Leaching of Pb from both soils followed the order: citric > oxalic > acetic acid. Mineral soil samples were shown to be more susceptible to leaching of Pb than samples characterised by a high content of organic matter. The leaching efficiency of citric acid was attributed to formation of stable complexes with Pb ions, which other acids are not capable of. Results obtained in the study are evidence that the extent of As and Pb leaching in contaminated surface and subsurface soil depends significantly on the types of carboxylic acid involved. The implications of the type of acid and the specific element that can be mobilised become increasingly significant where LMMOA concentrations are highest, such as in rhizosphere soil.

  11. Roasting-induced phase change and its influence on phosphorus removal through acid leaching for high-phosphorus iron ore

    Science.gov (United States)

    Yang, Min; Zhu, Qing-shan; Fan, Chuan-lin; Xie, Zhao-hui; Li, Hong-zhong

    2015-04-01

    In the present study, roasting-induced phase change and its influence on phosphorus removal via leaching has been investigated for high-phosphorus iron ore. The findings indicate that phosphorus in the ore is associated with goethite and exists mainly in amorphous Fe3PO7 phase. The phosphorus remains in the amorphous phase after being roasted below 300°C. Grattarolaite (Fe3PO7) is found in samples roasted at 600-700°C, revealing that phosphorus phase is transformed from the amorphous form to crystalline grattarolaite during roasting. Leaching tests on synthesized pure grattarolaite reveal a low rate of phosphorus removal by sulfuric acid leaching. When the roasting temperature is higher than 800°C, grattarolaite is found to react with alumina to form aluminum phosphate, and the reactivity of grattarolaite with alumina increases with increasing roasting temperature. Consequently, the rate of phosphorus removal also increases with increasing roasting temperature due to the formation of acid-soluble aluminum phosphate.

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

    Institute of Scientific and Technical Information of China (English)

    金程; 赵颖华; 李登新

    2011-01-01

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

  13. Bypass flow and its role in leaching of raised beds under different land use types on an acid sulphate soil.

    NARCIS (Netherlands)

    Minh, L.Q.; Tuong, T.P.; Booltink, H.W.G.; Mensvoort, van M.E.F.; Bouma, J.

    1997-01-01

    A better understanding of leaching processes in raised beds is useful in assessing management options for acid sulphate soils. Field and laboratory studies were carried out to quantify the effects of soil physical properties and bypass flow on leaching processes of new, 1-year-old and 2-year-old rai

  14. Kinetics of the Leaching Process of an Australian Gibbsitic Bauxite by Hydrochloric Acid

    Directory of Open Access Journals (Sweden)

    Aichun Zhao

    2016-01-01

    Full Text Available Gibbsitic bauxite from Australia was leached by hydrochloric acid in this work. Analysis on kinetics for the extraction of Al2O3 was quantitatively studied. It was concluded that the hydrochloric acid leaching process of gibbsitic bauxite was controlled by chemical reaction. Moreover, the mechanism for the dissolution followed the equation, ln⁡k=39.44-1.66×104(1/T, with an apparent activation energy of 137.90 kJ/mol, according to the equation of k=Ae-Ea/RT. This work aims to provide a good theory support for the process control by using a new method of alumina production from the low grade bauxite.

  15. 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.

  16. Autoclave leaching of molybdenite concentrates with catalytic additives of nitric acid

    Science.gov (United States)

    Smirnov, K. M.; Raspopov, N. A.; Shneerson, Ya. M.; Lapin, A. Yu.; Bitkov, G. A.; Men'shikov, Yu. A.; Paskhin, P. N.; Kirichenko, V. P.

    2010-07-01

    The scientific theoretical prerequisites for the use of small additives of nitric acid for the intensification of the autoclave oxidative leaching (AOL) of sulfide concentrates are checked in order to increase the degree of extraction of the base metal with a simultaneous decrease in the cost of the process. The technological parameters of the AOL conditions applied to molybdenite are also refined, and recommendations for a practical application of the apparatus of the process and for a decrease in its cost are made.

  17. Leaching kinetics of molybdenum from Ni-Mo ore in sulfuric acid solution with sodium peroxodisulfate as oxidant

    Institute of Scientific and Technical Information of China (English)

    刘志雄; 尹周澜; 陈义光; 熊利芝

    2015-01-01

    The leaching kinetics of molybdenum from Ni-Mo ore in sulfuric acid solution with sodium peroxodisulfate was studied. The effects including leaching temperature, reaction time, particle size, stirring speed, and concentrations of sulfuric acid and sodium peroxodisulfate were investigated. The leaching process of molybdenum from Ni-Mo ore is controlled by the chemical reaction through the solid layer across the unreacted shrinking core. The apparent activation energy of the leaching of molybdenum is calculated to be 41.0 kJ/mol and the leaching kinetics equation of molybdenum from Ni-Mo ore is expressed as 1−(1−a)1/3=3405.7exp[−41030.0/(RT)]t.

  18. Vanadium recovery from clay vanadium mineral using an acid leaching method

    Institute of Scientific and Technical Information of China (English)

    LI Haoran; FENG Yali; LIANG Jianglong; LUO Xiaobing; DU Zhuwei

    2008-01-01

    A technique including direct acid leaching,vanadium precipitation with alkaline,sodium hydroxide releaching,impurity removing by adjusting pH value,precipitation vanadium with ammonium chloride,and vanadium pentoxide by roasting steps was proposed according to the characteristic of Xichuan clay vanadium mineral.The factors influencing leaching vanadium such as temperature and the concentration of sulfuric acid were investigated and optimized.The experimental results indicate that the extract ratios of V2O5 can reach 94% and 92% at a sodium chlorate ratio of 3% and a manganese dioxide ratio of 3%,respectively.A completely chemical precipitation method was adopted to decontaminate and enrich the vanadium in the acid leaching solution.The X-ray diffraction (XRD) pattern and the purity analysis of vanadium pentoxide indicate that the purity of final vanadium pentoxide can reach 99% and meet the standard specifications.The total recovery can reach about 75%.The technique has the characteristics of simplicity,less investlnent,and more environment safety as compared with the traditional salt roasting method.

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

    International Nuclear Information System (INIS)

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

  20. Effect of storage of rice seeds on solute leaching and nucleic acid synthesis

    International Nuclear Information System (INIS)

    Rice (Oryza sativa Linn.) seeds of early varieties 'Ratna' and 'Jaya' and late varieties 'Suakalma' and 'Pankaj' remained viable for 12 to 16 months in normal storage. Conductivity of pooled leachates, leaching of soluble carbohydrate and nitrogen increased with duration of storage. While 32P uptake in isolated embryos and endosperms of fresh, 1-year and 2-year-old seeds showed a declining trend, its incorporation in nucleic acids did not vary significantly. The content of nucleic acid of seeds, however, decreased with an increase in the storage period. (auth.)

  1. A statistical approach to the experimental design of the sulfuric acid leaching of gold-copper ore

    Directory of Open Access Journals (Sweden)

    Mendes F.D.

    2003-01-01

    Full Text Available The high grade of copper in the Igarapé Bahia (Brazil gold-copper ore prevents the direct application of the classic cyanidation process. Copper oxides and sulfides react with cyanides in solution, causing a high consumption of leach reagent and thereby raising processing costs and decreasing recovery of gold. Studies have showm that a feasible route for this ore would be a pretreatment for copper minerals removal prior to the cyanidation stage. The goal of this experimental work was to study the experimental conditions required for copper removal from Igarapé Bahia gold-copper ore by sulfuric acid leaching by applying a statistical approach to the experimental design. By using the Plackett Burman method, it was possible to select the variables that had the largest influence on the percentage of copper extracted at the sulfuric acid leaching stage. These were temperature of leach solution, stirring speed, concentration of sulfuric acid in the leach solution and particle size of the ore. The influence of the individual effects of these variables and their interactions on the experimental response were analyzed by applying the replicated full factorial design method. Finally, the selected variables were optimized by the ascending path statistical method, which determined the best experimental conditions for leaching to achieve the highest percentage of copper extracted. Using the optimized conditions, the best leaching results showed a copper extraction of 75.5%.

  2. Succinic acid-based leaching system: A sustainable process for recovery of valuable metals from spent Li-ion batteries

    Science.gov (United States)

    Li, Li; Qu, Wenjie; Zhang, Xiaoxiao; Lu, Jun; Chen, Renjie; Wu, Feng; Amine, Khalil

    2015-05-01

    A hydrometallurgical method involving natural organic acid leaching has been developed for recovery of lithium and cobalt from the cathode active materials in spent lithium-ion batteries. Succinic acid is employed as leaching agent and H2O2 as reductant. The cobalt and lithium contents from the succinic acid-based treatment of spent batteries are determined by inductively coupled plasma-optical emission spectroscopy to calculate the leaching efficiency. The spent LiCoO2 samples after calcination and the residues after leaching are characterized by X-ray diffraction and scanning electron microscopy. The results show that nearly 100% of cobalt and more than 96% of lithium are leached under optimal conditions: succinic acid concentration of 1.5 mol L-1, H2O2 content of 4 vol.%, solid-to-liquid ratio of 15 g L-1, temperature of 70 °C, and reaction time of 40 min. Results are also given for fitting of the experimental data to acid leaching kinetic models.

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

    Institute of Scientific and Technical Information of China (English)

    蔡创开; 庄荣传; 林鸿汉

    2015-01-01

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

  4. Acid Leaching of SHS Produced MgO/TiB2

    OpenAIRE

    Lok, Jonathan Y.

    2006-01-01

    The stoichiometric Self-propagating High-temperature Synthesis (SHS) thermite reaction involving magnesium oxide (MgO), titanium dioxide (TiO2), and boron oxide (B2O3) forms titanium diboride (TiB2) and MgO as final products. Selective acid leaching is used to remove the MgO leaving high purity TiB2 powder. The SHS method to produce TiB2 is attractive because of the relatively low temperature required to initiate the reaction, fast reaction time, and product purity. This study investigates th...

  5. Reductive leaching of manganese from low-grade pyrolusite ore in sulfuric acid using pyrolysis-pretreated sawdust as a reductant

    Science.gov (United States)

    Feng, Ya-li; Zhang, Shi-yuan; Li, Hao-ran

    2016-03-01

    Manganese (Mn) leaching and recovery from low-grade pyrolusite ore were studied using sulfuric acid (H2SO4) as a leachant and pyrolysis-pretreated sawdust as a reductant. The effects of the dosage of pyrolysis-pretreated sawdust to pyrolusite ore, the concentration of sulfuric acid, the liquid/solid ratio, the leaching temperature, and the leaching time on manganese and iron leaching efficiencies were investigated. Analysis of manganese and iron leaching efficiencies revealed that a high manganese leaching efficiency was achieved with low iron extraction. The optimal leaching efficiency was determined to be 20wt% pyrolysis-pretreated sawdust and 3.0 mol/L H2SO4 using a liquid/ solid ratio of 6.0 mL/g for 90 min at 90°C. Other low-grade pyrolusite ores were tested, and the results showed that they responded well with manganese leaching efficiencies greater than 98%.

  6. A novel and efficient method combining acid leaching and thermal annealing for impurities removal from silicon intended for photovoltaic application

    Energy Technology Data Exchange (ETDEWEB)

    Khalifa, M. [Photovoltaic Laboratory, Research and Technology Centre of Energy, Borj-Cedria Science and Technology Park, BP 95, 2050 Hammam-Lif (Tunisia); Hajji, M. [Photovoltaic Laboratory, Research and Technology Centre of Energy, Borj-Cedria Science and Technology Park, BP 95, 2050 Hammam-Lif (Tunisia); High Institute of Electronics and Communications, Sfax University, PB 868 Sfax 3018 (Tunisia); Ezzaouia, H. [High Institute of Electronics and Communications, Sfax University, PB 868 Sfax 3018 (Tunisia)

    2012-10-15

    The aim of this work is the purification of MG-silicon powder using a method combining acid leaching and thermal annealing. It describes experiment carried out by using a tungsten lamps furnace (rapid thermal processing, RTP) to purify silicon powder under controlled atmosphere. This process enables to segregate the impurities to the surface of silicon powder where they can be extracted by partial dissolution in acids. Obtained silicon was investigated by Inductively Coupled Plasma Atomic Emission Spectrometry (ICP-AES) method. Major impurities present in silicon powder were Al, K, Fe, Na, Ca, Mg and B. After purification the concentration of major impurities significantly decreased. (copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  7. Influence of Polyethylene and Oxidized Polyethylene Wax Emulsions on Leaching Dynamics of Boric Acid from Impregnated Spruce Wood

    Directory of Open Access Journals (Sweden)

    Boštjan Lesar

    2010-12-01

    Full Text Available Boron biocides belong to the most frequently used ingredients of commercial wood preservatives. They are very effective fungicides and insecticides, but they do not react with wood and thus leach from it in wet applications. This fact signifi cantly limits use of boron compounds in the field of wood preservation. In order to reduce leaching of boric acid, the emulsion of polyethylene (WE1 and an emulsion of oxidized polyethylene (WE6 wax were combined with boric acid (cB = 0.1 % or 0.5 % of boron. Spruce wood specimens were vacuum impregnated and afterwards leached according to the prCEN/TS 15119-1, EN 1250-2 and EN 84 procedures. The results showed that the boron leaching is predominantly infl uenced by moisture content of wood during leaching, and furthermore by the concentration gradient (frequency of water replacement. The fact that the prCEN/TS 15119-1 leaching procedure is less severe than other two methods is also refl ected in the results. The results of the EN 84 and ENV 1250 test are comparable, while the results of the prCEN/TS 15119-1 testing are not in line with the other two methods. Considerable portions of boron are leached from wood in the first leaching cycles, already. WE6 wax emulsion (oxidized polyethylene wax emulsion in combination with heat treatment reduces boron leaching to a certain extent. On the other hand, impregnation of wood with WE1 (polyethylene wax emulsion does not reduce it and it even enhances it.

  8. Leaching lithium from the anode electrode materials of spent lithium-ion batteries by hydrochloric acid (HCl).

    Science.gov (United States)

    Guo, Yang; Li, Feng; Zhu, Haochen; Li, Guangming; Huang, Juwen; He, Wenzhi

    2016-05-01

    Spent lithium-ion batteries (LIBs) are considered as an important secondary resource for its high contents of valuable components, such as lithium and cobalt. Currently, studies mainly focus on the recycling of cathode electrodes. There are few studies concentrating on the recovery of anode electrodes. In this work, based on the analysis result of high amount of lithium contained in the anode electrode, the acid leaching process was applied to recycle lithium from anode electrodes of spent LIBs. Hydrochloric acid was introduced as leaching reagent, and hydrogen peroxide as reducing agent. Within the range of experiment performed, hydrogen peroxide was found to have little effect on lithium leaching process. The highest leaching recovery of 99.4wt% Li was obtained at leaching temperature of 80°C, 3M hydrochloric acid and S/L ratio of 1:50g/ml for 90min. The graphite configuration with a better crystal structure obtained after the leaching process can also be recycled.

  9. Behaviors of clay minerals in dilute sulphuric acid and sodium carbonate leaching

    International Nuclear Information System (INIS)

    The dissolution properties and acid consumption of kaolinite, montmorillonite, illite and their dewatered products roasted at temperature 600-800 deg C in dilute sulphuric acid are studied. The results indicate that the dissolubility of kaolinite is smaller, montmorillonite is greater and illite is between them. But after roasting at temperature 600-800 deg C, the dissolubility of dewatered kaolinite is greater, dewatered montmorillonite is much smaller, and the dewatered illite is between them. The study on reaction products of kaolinite with sodium carbonate in pressurized sodium carbonate leaching indicates that the reaction product is the colloid multiple sodium silicate at lower temperature (below 120 deg C), the crystalline hydroxysodalite at higher temperature (above 160 deg C)

  10. Leaching behavior of heavy metals and transformation of their speciation in polluted soil receiving simulated acid rain.

    Directory of Open Access Journals (Sweden)

    Shun-an Zheng

    Full Text Available Heavy metals that leach from contaminated soils under acid rain are of increasing concern. In this study, simulated acid rain (SAR was pumped through columns of artificially contaminated purple soil. Column leaching tests and sequential extraction were conducted for the heavy metals Cu, Pb, Cd, and Zn to determine the extent of their leaching as well as to examine the transformation of their speciation in the artificially contaminated soil columns. Results showed that the maximum leachate concentrations of Cu, Pb, Cd, and Zn were less than those specified in the Chinese Quality Standards for Groundwater (Grade IV, thereby suggesting that the heavy metals that leached from the polluted purple soil receiving acid rain may not pose as risks to water quality. Most of the Pb and Cd leachate concentrations were below their detection limits. By contrast, higher Cu and Zn leachate concentrations were found because they were released by the soil in larger amounts as compared with those of Pb and Cd. The differences in the Cu and Zn leachate concentrations between the controls (SAR at pH 5.6 and the treatments (SAR at pH 3.0 and 4.5 were significant. Similar trends were observed in the total leached amounts of Cu and Zn. The proportions of Cu, Pb, Cd, and Zn in the EXC and OX fractions were generally increased after the leaching experiment at three pH levels, whereas those of the RES, OM, and CAR fractions were slightly decreased. Acid rain favors the leaching of heavy metals from the contaminated purple soil and makes the heavy metal fractions become more labile. Moreover, a pH decrease from 5.6 to 3.0 significantly enhanced such effects.

  11. Leaching behavior of heavy metals and transformation of their speciation in polluted soil receiving simulated acid rain.

    Science.gov (United States)

    Zheng, Shun-an; Zheng, Xiangqun; Chen, Chun

    2012-01-01

    Heavy metals that leach from contaminated soils under acid rain are of increasing concern. In this study, simulated acid rain (SAR) was pumped through columns of artificially contaminated purple soil. Column leaching tests and sequential extraction were conducted for the heavy metals Cu, Pb, Cd, and Zn to determine the extent of their leaching as well as to examine the transformation of their speciation in the artificially contaminated soil columns. Results showed that the maximum leachate concentrations of Cu, Pb, Cd, and Zn were less than those specified in the Chinese Quality Standards for Groundwater (Grade IV), thereby suggesting that the heavy metals that leached from the polluted purple soil receiving acid rain may not pose as risks to water quality. Most of the Pb and Cd leachate concentrations were below their detection limits. By contrast, higher Cu and Zn leachate concentrations were found because they were released by the soil in larger amounts as compared with those of Pb and Cd. The differences in the Cu and Zn leachate concentrations between the controls (SAR at pH 5.6) and the treatments (SAR at pH 3.0 and 4.5) were significant. Similar trends were observed in the total leached amounts of Cu and Zn. The proportions of Cu, Pb, Cd, and Zn in the EXC and OX fractions were generally increased after the leaching experiment at three pH levels, whereas those of the RES, OM, and CAR fractions were slightly decreased. Acid rain favors the leaching of heavy metals from the contaminated purple soil and makes the heavy metal fractions become more labile. Moreover, a pH decrease from 5.6 to 3.0 significantly enhanced such effects. PMID:23185399

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

    Institute of Scientific and Technical Information of China (English)

    马喜红; 覃文庆; 吴雪兰; 任浏祎

    2012-01-01

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

  13. An Analytical Model Approach for the Dissolution Kinetics of Magnesite Ore Using Ascorbic Acid as Leaching Agent

    Directory of Open Access Journals (Sweden)

    Nadeem Raza

    2013-01-01

    Full Text Available Ascorbic acid was used as leaching agent to investigate the dissolution kinetics of natural magnesite ore. The effects of various reaction parameters such as acid concentration, liquid-solid ratio, particle size, stirring speed, and temperature were determined on dissolution kinetics of the magnesite ore. It was found that the dissolution rate increased with increase in acid concentration, liquid-solid ratio, stirring speed, and temperature and decrease in the particle size of the ore. The graphical and statistical methods were applied to analyze the kinetic data, and it was evaluated that the leaching process was controlled by the chemical reaction, that is, . The activation energy of the leaching process was found to be 57.244 kJ mol−1 over the reaction temperature range from 313 to 343 K.

  14. Study of radionuclide leaching from the residues of K Basin sludge dissolution

    Energy Technology Data Exchange (ETDEWEB)

    Bechtold, D.B.

    1998-07-30

    The sludges remaining in the K Basins after removal of the spent N Reactor nuclear fuel will be conditioned for disposal. After conditioning, an acid-insoluble residue will remain that may require further leaching to properly condition it for disposal. This document presents a literature study to identify and recommend one or more chemical leaching treatments for laboratory testing, based on the likely compositions of the residues. The processes identified are a nitric acid cerate leach, a silver-catalyzed persulfate leach, a nitric hydrofluoric acid leach, an oxalic citric acid reactor decontamination leach, a nitric hydrochloric acid leach, a ammonium fluoride nitrate leach, and a HEOPA formate dehydesulfoxylate leach. All processes except the last two are recommended for testing in that order.

  15. Recovery of lead from smelting fly ash of waste lead-acid battery by leaching and electrowinning.

    Science.gov (United States)

    Chen, Chuh-Shun; Shih, Yu-Jen; Huang, Yao-Hui

    2016-06-01

    Fly ash that was enriched with lead (Pb), formed as an intermediate in waste lead-acid battery (WLAB) smelting, was recycled by the hydro-electrometallurgy. Characterization of fly ash thereof indicated that the Pb was in the forms of PbSO4 (anglesite) and Pb2OSO4 (lanarkite). Nitric acid and sodium hydroxide were firstly used to study the leaching of the fly ash sample, which was affected by leachant dosage and solid-to-liquid ratio (S/L). At an S/L of 60gL(-1), the leachability of Pb was 43% and 67% in 2M acidic and basic solutions, respectively, based on an average 70wt% of Pb in the original fly ash. Anglesite was completely soluble in NaOH and lanarkite was mildly soluble in HNO3. Pb was recovered from the pregnant leach solution within an electrolytic cell constructed with graphite or RuO2/IrO2-coated titanium (Ti-DSA) anodes and a stainless steel cathode. Properties of anodes deposited with lead dioxides were analyzed by cyclic voltammetry. The optimized parameters of electrowinning were 2M NaOH leachant, a current density of 0.75Adm(-2) and an electrolytic process duration of 120min, which yielded a Pb removal of higher than 99% and a specific energy consumption of 0.57Whg(-1). This process constitutes an eco-friendly and economic alternative to the presently utilized secondary pyrometallurgy for treating lead-containing fly ash.

  16. Oxidative leaching process with cupric ion in hydrochloric acid media for recovery of Pd and Rh from spent catalytic converters

    Energy Technology Data Exchange (ETDEWEB)

    Nogueira, C.A., E-mail: carlos.nogueira@lneg.pt [Laboratório Nacional de Energia e Geologia, I.P., Campus do Lumiar, 1649-038 Lisboa (Portugal); Paiva, A.P., E-mail: appaiva@fc.ul.pt [Centro de Química e Bioquímica, Departamento de Química e Bioquímica, Faculdade de Ciências da Universidade de Lisboa, 1749-016 Lisboa (Portugal); Oliveira, P.C. [Laboratório Nacional de Energia e Geologia, I.P., Campus do Lumiar, 1649-038 Lisboa (Portugal); Costa, M.C., E-mail: mcorada@ualg.pt [Centro de Ciências do Mar, Departamento de Química e Farmácia, Faculdade de Ciências e de Tecnologia, Campus de Gambelas, 8005-139 Faro (Portugal); Costa, A.M. Rosa da, E-mail: amcosta@ualg.pt [Centro de Investigação em Química do Algarve, Departamento de Química e Farmácia, Faculdade de Ciências e de Tecnologia, Campus de Gambelas, 8005-139 Faro (Portugal)

    2014-08-15

    Highlights: • A new leaching process based on Cu{sup 2+}/HCl media for recovering Pd and Rh from spent autocatalytic converters is presented. • Palladium and rhodium were efficiently leached, with attained maximum yields of 95% and 86%, respectively. • Temperature, time, and HCl and Cu{sup 2+} concentrations were found to be significant factors in the leaching of Pd and Rh. - Abstract: The recycling of platinum-group metals from wastes such as autocatalytic converters is getting growing attention due to the scarcity of these precious metals and the market pressure originated by increase of demand in current and emerging applications. Hydrometallurgical treatment of such wastes is an alternative way to the most usual pyrometallurgical processes based on smelter operations. This paper focuses on the development of a leaching process using cupric chloride as oxidising agent, in HCl media, for recovery of palladium and rhodium from a spent catalyst. The chloride media allows the adequate conditions for oxidising and solubilising the metals, as demonstrated by equilibrium calculations based on thermodynamic data. The experimental study of the leaching process revealed that Pd solubilisation is clearly easier than that of Rh. The factors temperature, time, and HCl and Cu{sup 2+} concentrations were significant regarding Pd and Rh leaching, the latter requiring higher factor values to achieve the same results. Leaching yields of 95% Pd and 86% Rh were achieved under optimised conditions (T = 80 °C, t = 4 h, [HCl] = 6 M, [Cu{sup 2+}] = 0.3 M)

  17. Acid leaching of scheelite concentrates; Lixiviacion acida de concentrado de scheelita

    Energy Technology Data Exchange (ETDEWEB)

    Navarro, P.; Vargas, C.; Alguacil, F. J.

    2005-07-01

    The acid leaching in hydrochloric media of a tungsten concentrate (scheelite, CaWO{sub 4}) was studied. Of the above-mentioned, an insoluble solid (H{sub 2}WO{sub 4}) was obtained which were treated with an alkaline solution of sodium hydroxide, achieving the complete solubilization of the tungsten as wolframate ion (WO''2{sub 4}). The transformed fraction of tungsten increases with the temperature, as well as with a finer grain. A maximum dissolution of 88.5% (400 g/l HCL, 363 K and 20 {mu}m of particle size) was achieved for a 3 h process, of the dissolution process was interpreted by the recessive core model with formation of a layer of solid product for the whole range of variation of the parameters in study. the activation energy value was found to be 28.0kJ/mol. (Author) 6 refs.

  18. Hydrometallurgical recovery of metal values from sulfuric acid leaching liquor of spent lithium-ion batteries

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Xiangping; Chen, Yongbin; Zhou, Tao, E-mail: zhoutao@csu.edu.cn; Liu, Depei; Hu, Hang; Fan, Shaoyun

    2015-04-15

    Highlights: • Selective precipitation and solvent extraction were adopted. • Nickel, cobalt and lithium were selectively precipitated. • Co-D2EHPA was employed as high-efficiency extraction reagent for manganese. • High recovery percentages could be achieved for all metal values. - Abstract: Environmentally hazardous substances contained in spent Li-ion batteries, such as heavy metals and nocuous organics, will pose a threat to the environment and human health. On the other hand, the sustainable recycling of spent lithium-ion batteries may bring about environmental and economic benefits. In this study, a hydrometallurgical process was adopted for the comprehensive recovery of nickel, manganese, cobalt and lithium from sulfuric acid leaching liquor from waste cathode materials of spent lithium-ion batteries. First, nickel ions were selectively precipitated and recovered using dimethylglyoxime reagent. Recycled dimethylglyoxime could be re-used as precipitant for nickel and revealed similar precipitation performance compared with fresh dimethylglyoxime. Then the separation of manganese and cobalt was conducted by solvent extraction method using cobalt loaded D2EHPA. And McCabe–Thiele isotherm was employed for the prediction of the degree of separation and the number of extraction stages needed at specific experimental conditions. Finally, cobalt and lithium were sequentially precipitated and recovered as CoC{sub 2}O{sub 4}⋅2H{sub 2}O and Li{sub 2}CO{sub 3} using ammonium oxalate solution and saturated sodium carbonate solution, respectively. Recovery efficiencies could be attained as follows: 98.7% for Ni; 97.1% for Mn, 98.2% for Co and 81.0% for Li under optimized experimental conditions. This hydrometallurgical process may promise a candidate for the effective separation and recovery of metal values from the sulfuric acid leaching liquor.

  19. Copper Leaching from Copper Residue with Oxygen in Sulfuric Acid/Chloride Solution DENG Tong 1,%在硫酸/氯化物深液中用氧气浸出铜渣中的铜

    Institute of Scientific and Technical Information of China (English)

    邓彤; 文震

    2000-01-01

    Leaching of a copper residue, produced by selected oxidation leaching of a nickel matte, in oxygenated sulfuric acid solution with the participation of chloride was investigated. The effects of quantity of chloride, flowrate of oxygen, concentration of sulfuric acid and temperature were discussed as leaching variables. Addition of chloride in small amount into the leach slurry was justified in enhancing copper leaching from the residue.

  20. Sustainable Soil Washing: Shredded Card Filtration of Potentially Toxic Elements after Leaching from Soil Using Organic Acid Solutions.

    Directory of Open Access Journals (Sweden)

    Christopher Ash

    Full Text Available Shredded card (SC was assessed for use as a sorbent of potentially toxic elements (PTE carried from contaminated soil in various leachates (oxalic acid, formic acid, CaCl2, water. We further assessed SC for retention of PTE, using acidified water (pH 3.4. Vertical columns and a peristaltic pump were used to leach PTE from soils (O and A/B horizons before passing through SC. Sorption onto SC was studied by comparing leachates, and by monitoring total PTE contents on SC before and after leaching. SC buffers against acidic soil conditions that promote metals solubility; considerable increases in solution pH (+4.49 were observed. Greatest differences in solution PTE content after leaching with/without SC occurred for Pb. In oxalic acid, As, Cd, Pb showed a high level of sorption (25, 15, and 58x more of the respective PTE in leachates without SC. In formic acid, Pb sorption was highly efficient (219x more Pb in leachate without SC. In water, only Pb showed high sorption (191x more Pb in leachate without SC. In desorption experiments, release of PTE from SC varied according to the source of PTE (organic/mineral soil, and type of solvent used. Arsenic was the PTE most readily leached in desorption experiments. Low As sorption from water was followed by fast release (70% As released from SC. A high rate of Cd sorption from organic acid solutions was followed by strong retention (~12% Cd desorption. SC also retained Pb after sorption from water, with subsequent losses of ≤8.5% of total bound Pb. The proposed use of this material is for the filtration of PTE from extract solution following soil washing. Low-molecular-mass organic acids offer a less destructive, biodegradable alternative to strong inorganic acids for soil washing.

  1. Sustainable Soil Washing: Shredded Card Filtration of Potentially Toxic Elements after Leaching from Soil Using Organic Acid Solutions.

    Science.gov (United States)

    Ash, Christopher; Drábek, Ondřej; Tejnecký, Václav; Jehlička, Jan; Michon, Ninon; Borůvka, Luboš

    2016-01-01

    Shredded card (SC) was assessed for use as a sorbent of potentially toxic elements (PTE) carried from contaminated soil in various leachates (oxalic acid, formic acid, CaCl2, water). We further assessed SC for retention of PTE, using acidified water (pH 3.4). Vertical columns and a peristaltic pump were used to leach PTE from soils (O and A/B horizons) before passing through SC. Sorption onto SC was studied by comparing leachates, and by monitoring total PTE contents on SC before and after leaching. SC buffers against acidic soil conditions that promote metals solubility; considerable increases in solution pH (+4.49) were observed. Greatest differences in solution PTE content after leaching with/without SC occurred for Pb. In oxalic acid, As, Cd, Pb showed a high level of sorption (25, 15, and 58x more of the respective PTE in leachates without SC). In formic acid, Pb sorption was highly efficient (219x more Pb in leachate without SC). In water, only Pb showed high sorption (191x more Pb in leachate without SC). In desorption experiments, release of PTE from SC varied according to the source of PTE (organic/mineral soil), and type of solvent used. Arsenic was the PTE most readily leached in desorption experiments. Low As sorption from water was followed by fast release (70% As released from SC). A high rate of Cd sorption from organic acid solutions was followed by strong retention (~12% Cd desorption). SC also retained Pb after sorption from water, with subsequent losses of ≤8.5% of total bound Pb. The proposed use of this material is for the filtration of PTE from extract solution following soil washing. Low-molecular-mass organic acids offer a less destructive, biodegradable alternative to strong inorganic acids for soil washing. PMID:26900684

  2. 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.

  3. 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.

  4. Experimental Study on Acid Leaching of Lead Matte%铅冰铜盐酸浸出试验研究

    Institute of Scientific and Technical Information of China (English)

    蒋朝金; 黄海飞; 杨跃新

    2015-01-01

    采用盐酸加入双氧水氧化浸出铅冰铜,使铅冰铜中的铜与铅、银、金等金属分离而分别回收,探索从铅冰铜高效、清洁回收有价金属的新工艺。通过试验,详细考察盐酸起始浓度、氧化剂的用量、液固比、反应温度、搅拌速度和浸出时间对铜浸出率的影响,得出铅冰铜酸性氧化浸出的最佳条件。%The oxidation leaching of lead matte by adding hydrogen peroxide under hydrochloric acid was carried out to separate and recycle the Cu,Pb,Ag,Au and other metals,so as to explore a new technology of high efficiency and clean recycling of valuable metals.Through the test,the effect of initial concentration of hydrochloric acid,oxidant dosage,liquid solid ratio,reaction temperature,stirring speed and leaching time was investigated in detail on the leaching rate of copper,and the optimum leaching condition of lead matte was achieved.

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

    Science.gov (United States)

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

    2010-01-01

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

  6. Study of the Extraction Kinetics of Lithium by Leaching β-Spodumene with Hydrofluoric Acid

    Directory of Open Access Journals (Sweden)

    Gustavo D. Rosales

    2016-09-01

    Full Text Available Parameters affecting the kinetics of the dissolution of β-spodumene with hydrofluoric acid have been investigated. The experimental tests were carried out in a closed vessel. The influence of several parameters, such as stirring speed, temperature, and reaction time were studied in order to deduce the kinetics of the dissolution reaction. The other parameters, particle size −45 μm; HF concentration 4% v/v, and the solid–liquid ratio 0.95% w/v were kept constant. The results indicate that the stirring speed does not have an important effect on the dissolution of the mineral above 330 rpm. The extent of the leaching of β-spodumene increases with temperature and reaction time augmentations. Scanning electron microscope (SEM analyses of some residues in which the conversion was lower than 30% indicated a selective attack on certain zones of the particle. The treatment of the experimental data was carried out using the Modelado software. The model that best represents the dissolution of the mineral is the following: ln(1 − X = −b1 [ln(1 + b2t − b2t/(1 + b2t]. This model is based on “nucleation and growth of nuclei” theory, and describes the style of attack physically observed by SEM on the residues.

  7. Methylmercury determination in biological samples using electrothermal atomic absorption spectrometry after acid leaching extraction

    Energy Technology Data Exchange (ETDEWEB)

    Saber-Tehrani, Mohammad; Hashemi-Moghaddam, Hamid; Givianrad, Mohammad Hadi; Abroomand-Azar, Parviz [Islamic Azad University, Department of Chemistry, Science and Research Branch, Tehran (Iran)

    2006-11-15

    An efficient and sensitive method for the determination of methylmercury in biological samples was developed based on acid leaching extraction of methylmercury into toluene. Methylmercury in the organic phase was determined by electrothermal atomic absorption spectrometry (ETAAS). The methylmercury signal was enhanced and the reproducibility increased by formation of certain complexes and addition of Pd-DDC modifier. The complex of methylmercury with DDC produced the optimum analytical signal in terms of sensitivity and reproducibility compared to complexes with dithizone, cysteine, 1,10-phenanthroline, and diethyldithiocarbamate. Method performance was optimized by modifying parameters such as temperature of mineralization, atomization, and gas flow rate. The limit of detection for methylmercury determination was 0.015 {mu}g g{sup -1} and the RSD of the whole procedure was 12% for human teeth samples (n=5) and 15.8% for hair samples (n=5). The method's accuracy was investigated by using NIES-13 and by spiking the samples with different amounts of methylmercury. The results were in good agreement with the certified values and the recoveries were 88-95%. (orig.)

  8. Leaching mechanism of zinc powder replacement residue containing gallium and germanium by high pressure acid leaching%锌粉置换镓锗渣高压酸浸的浸出机理

    Institute of Scientific and Technical Information of China (English)

    刘付朋; 刘志宏; 李玉虎; 刘智勇; 李启厚

    2014-01-01

    The high pressure acid leaching of zinc powder replacement residue containing gallium and germanium was carried out. The effects of sulfuric acid concentration, liquid to solid ratio, time, temperature, as well as the kind and concentration of leaching assistant agents on the leaching rates of gallium and germanium were studied, the filterabilities of the leaching residues were also investigated. The results show that increasing sulfuric acid concentration till 156 g/L benefits the leaching of gallium and germanium. Above this point, the leaching rate of germanium will decrease. The increase of leaching time or temperature has little influence on the leaching rates of gallium and germanium, but the filterabilities of leaching residues are improved obviously. Adding cadmium nitrate or sodium nitrate can improve the leaching of gallium and germanium, moreover, adding cadmium nitrate can also improves the filterability of the leaching residue sharply. The sample of zinc powder replacement residues is leached for 3 h under the conditions of sulfuric acid concentration of 156 g/L, cadmium nitrate concentration of 60 g/L as leaching assistant agent, liquid to solid ratio of 8, temperature of 150℃, the leaching rates obtained are over 98% for gallium and over 94% for germanium, respectively. Moreover, the filterability of the leaching residue is 20 times more than that of the residue obtained under normal pressure acid leaching condition.%研究锌粉置换镓锗渣的高压酸浸过程,考察硫酸浓度、液固比、浸出时间、浸出温度、助浸剂种类和添加量对Ga、Ge浸出率以及浸出渣过滤性能的影响。结果表明:增加硫酸浓度有利于Ga、Ge的浸出,但硫酸浓度超过156 g/L后,反而不利于Ge的浸出。浸出时间和温度对Ga、Ge浸出率影响较小,但增加浸出时间或提高反应温度均有利于改善浸出渣的过滤性能。添加硝酸钠或硝酸钙均可促进Ga、Ge

  9. Reductive atmospheric acid leaching of spent alkaline batteries in H2SO4/Na2SO3 solutions

    Science.gov (United States)

    Morcali, Mehmet Hakan

    2015-07-01

    This work studies the optimum reductive leaching process for manganese and zinc recovery from spent alkaline battery paste. The effects of reducing agents, acid concentration, pulp density, reaction temperature, and leaching time on the dissolution of manganese and zinc were investigated in detail. Manganese dissolution by reductive acidic media is an intermediate-controlled process with an activation energy of 12.28 kJ·mol-1. After being leached, manganese and zinc were selectively precipitated with sodium hydroxide. The zinc was entirely converted into zincate (Zn(OH){4/2-}) ions and thus did not co-precipitate with manganese hydroxide during this treatment (2.0 M NaOH, 90 min, 200 r/min, pH > 13). After the manganese was removed from the solution, the Zn(OH){4/2-} was precipitated as zinc sulfate in the presence of sulfuric acid. The results indicated that this process could be effective in recovering manganese and zinc from alkaline batteries.

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

    Directory of Open Access Journals (Sweden)

    E. Gikonyo

    2010-01-01

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

  11. Study on Leaching Process of Germanium Fly Ash with Sulfuric Acid%含锗烟尘的硫酸浸出工艺研究

    Institute of Scientific and Technical Information of China (English)

    郑东升; 肖松; 梁杰

    2012-01-01

    为简化含锗烟尘浸出过程,提出一段硫酸浸出工艺。浸出工艺条件为:浸出温度90℃,初始硫酸质量浓度120g/L,液固比8mL/g,浸出时间2.5h,搅拌转速120r/min。在该条件下,锌、锗浸出率分别为99.1%和87.61%左右,最终硫酸质量浓度约34.80g/L。去除不溶性锗后,锗浸出率可达到97.21%。%To simplify the leaching process of germanium fly ash, the one stage sulfuric acid leaching process was studied. The result shows the leaching processing as following: leaching temperature 90℃ initial sulfuric acid concentration 120 g/L, ratio of hquid to solid 5 mL/g, leaching time 2 h, and mixing speed 120 r/min. Under these conditions, the leaching rates of Zn and Ge were about 99.1% and 87.61%, and the concentration of end acid is about 34.80 g/L, and by removal of insoluble germanium, the leaching rate of Germanium could be about 97.21%. Zinc and Germanium can be effectively leached from Germanium fly ash in the leaching process, and the leaching technique is effective and stable.

  12. Sulfate retention and cation leaching of forest soils in response to acid additions

    International Nuclear Information System (INIS)

    Much research within the past decade has focused on the effects of increased sulfur (S) deposition on surface waters. As inputs of S deposition as SO4(2-) build up in the soil over time, the concentration of SO4(2-) leaching from soils may also increase. Leachate SO4(2-) concentrations were greater for the high-S than for the low-S treatment for each soil type, resulting in greater cation leachate concentrations for soils that received the high-S treatment. Calcium was the primary base cation in both the Spodosol and Alfisol leachates. Declining concentrations of base cations and NH4(+) over the length of the study led to an increase in Al(3+) concentrations and decrease in pH for some of the Spodosol leachates. It is difficult to extrapolate their laboratory rates of change to the BBWM catchments because of differences between the experiment and field conditions. Soil temperature, the amount and rate of S application, and the total mass of soil exposed to treatment were hypothesized to be important factors affecting net S retention in Spodosols under field conditions. However, the authors feel that SO4(2-) adsorption under field conditions would still be the primary mechanism of S retention because of similarities between SO4(2-) concentrations in treatment solutions used for the present experiment and those in natural throughfall solutions

  13. 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

  14. 锌焙砂一段酸性浸出试验研究%Study on Single -stage Acid Leaching of Zinc Calcine

    Institute of Scientific and Technical Information of China (English)

    阙绍娟; 陈燕清; 马少健; 何春林

    2011-01-01

    The test on single - stage acid leaching of zinc calcine had been proceed. The effects of stirring speed, particle size, leaching temperature, initial acidity of sulfuric acid and ratio of liquid to solid were studied on the leaching rates of zinc and iron. The results showed that initial acidity of sulfuric acid and liquid -solid ratio were the most important factors on leaching. Under the condition of leaching temperature 55℃, initial acidity of sulfuric acid 120 g/L, leaching time 0.5 h,liquid- solid ratio 6: 1 and stirring rate 500 r/min, the leaching rate of zinc and iron was 81.33% and 3.45% respectively, which basically achieved selective leaching of zinc and iron.%对锌焙砂进行了一段酸性浸出试验研究,考察了搅拌速度、矿样粒度、浸出温度、初始酸度、液固比等因素对Zn和Fe浸出率的影响规律.试验结果表明:初始酸度和液固比是影响浸出的最重要因素,锌焙砂在55℃、初始酸度120 g/L、液同比6:1和搅拌速度为500 r/min的条件下浸出0.5 h,Zn的浸出率为81.33%、Fe的浸出率为3.45%,基本能够实现Zn、Fe的选择性浸出.

  15. 镀锌灰的热酸浸出和除铁试验研究%Research on Leaching of Zinc Using Hot Acid From Zinc Ash and Removal of Iron From Leaching Solution by Jarosite Process

    Institute of Scientific and Technical Information of China (English)

    何小凤; 李运刚; 陈金

    2014-01-01

    By single factor experiments ,leaching of zinc using hot acid from zinc ash and removal of iron from the leaching solution by jarosite process were researched .The results show that the optimum conditions for leaching zinc are determined as follow s initial acid concentration of 150 g/L ,leaching temperature of 90 ℃ ,ratio between liquid volume and solid mass of 6∶1 .At the optimum conditions , the leaching rate of zinc is more than 97% .Removal of iron is over 98% under the conditions of temperature of 90 ℃ ,reaction time of 3 h .%采用单因素试验法研究了从镀锌灰中热酸浸出锌及黄钾铁矾法除铁。试验结果表明:在硫酸初始质量浓度为150 g/L、浸出温度90℃、浸出时间3 h、液固体积质量比6∶1条件下,锌浸出率在97%以上;用黄钾铁矾法除铁,在温度90℃、反应时间3 h条件下,铁去除率在98%以上。

  16. Long-Term Acid-Generating and Metal Leaching Potential of a Sub-Arctic Oil Shale

    Directory of Open Access Journals (Sweden)

    Kathryn A. Mumford

    2014-04-01

    Full Text Available Shales are increasingly being exploited for oil and unconventional gas. Exploitation of sub-arctic oil shales requires the creation of gravel pads to elevate workings above the heaving effects of ground ice. These gravel pads can potentially generate acidic leachate, which can enhance the mobility of metals from the shale. To examine this potential, pyrite-bearing shale originating from sub-Arctic gravel pad sites were subjected to leaching tests for 600 days at initial pH values ranging from 2 to 5, to simulate potential real world conditions. At set times over the 600 day experiment, pH, oxidation reduction potential (ORP, dissolved oxygen and temperature were recorded and small liquid samples withdrawn and analysed for elemental concentrations using total reflection X-ray fluorescence spectrometry (TRXRF. Six of eight shale samples were found to be acid generating, with pH declining and ORP becoming increasingly positive after 100 days. Two of the eight shale samples produced increasingly alkaline leachate conditions with relatively low ORP after 100 days, indicating an inbuilt buffering capacity. By 600 days the buffering capacity of all samples had been consumed and all leachate samples were acidic. TRXRF analyses demonstrated significant potential for the leaching of S, Fe, Ni, Cu, Zn and Mn with greatest concentrations found in reaction vessels with most acidic pH and highest ORP.

  17. The leaching behaviour of a Ni-Cu-Co sulphide ore in an oxidative pressure-acid medium / Danie Strydom Smit

    OpenAIRE

    Smit, Danie Strydom

    2001-01-01

    Hydrometallurgical processing of sulphide concentrates is an attractive method for the selective extraction of valuable metals. The dissolution of minerals in a leaching process involves several electrochemical parameters that need to be investigated• to ensure the development and growth of the base metal industry in South Africa. A study has been carried out to elucidate the leaching mechanism of a nickel-coppercobalt sulphide concentrate in an oxidative pressure-acid medium. ...

  18. Leaching of cadmium, chromium, copper, lead, and zinc from two slag dumps with different environmental exposure periods under dynamic acidic condition.

    Science.gov (United States)

    Jin, Zhisheng; Liu, Taoze; Yang, Yuangen; Jackson, Daniel

    2014-06-01

    Over the past few decades, zinc smelting activities in Guizhou, China have produced numerous slag dumps, which are often dispersed on roadsides and hill slopes throughout the region. During periods of acid rain, these exposed slags release heavy metals into surface water bodies. A column leaching study was designed to test the potential release of the heavy metals cadmium (Cd), chromium (Cr), copper (Cu), lead (Pb), and zinc (Zn) under simulated acid rain events. Two slags with varying environmental exposure periods were packed in columns and subjected to leaching solutions of pH 3.5, 5.5, or DI H2O at intervals of 1, 7, 14, 28, 56d. Pulse concentrations of Cd in leachate were found above 5μg/L, Cr, Pb, and Zn >10μg/L, whereas, Cu reached 10μg/L. After five leaching events, the leachability (percentage of cumulative heavy metal leached after five leaching events as in its respective total concentration in slags) of Cd was 0.05 percent and 0.035 percent from the old and young slag, respectively. Cr (0.035 percent and 0.05 percent) was greater than Cu (0.002 percent and 0.005 percent) and Zn (0.006 percent and 0.003 percent), while the lowest leachability was observed for Pb (0.0005 percent and 0.0002 percent) from the old and young slags, respectively. Reaction rates (release amount of heavy metals in certain period of leaching) of heavy metals in the leachates demonstrated the sequence of Zn>Cr>Cd, Cu>Pb. Leaching release of heavy metals was jointly affected by the pH of leaching solution and mineral composition of slags (including chemical forms of Cd, Cr, Cu, Pb, and Zn). Environmental exposure period of slags, resulting in the alteration of minerals, could affect the release process of heavy metals in leaching as well. PMID:24632122

  19. Mechanisms of Vanadium Recovery from Stone Coal by Novel BaCO3/CaO Composite Additive Roasting and Acid Leaching Technology

    Directory of Open Access Journals (Sweden)

    Zhenlei Cai

    2016-03-01

    Full Text Available In this report, the vanadium recovery mechanisms by novel BaCO3/CaO composite additive roasting and acid leaching technology, including the phase transformations and the vanadium leaching kinetics, were studied. The purpose of this manuscript is to realize and improve the vanadium recovery from stone coal using BaCO3/CaO as the composite additive. The results indicated that during the composite additive BaCO3/CaO roasting process, the monoclinic crystalline structure of muscovite (K(Al,V2[Si3AlO10](OH2 was converted into the hexagonal crystalline structure of BaSi4O9 and the tetragonal crystalline structure of Gehlenite (Ca2Al2SiO7, which could, therefore, facilitate the release and extraction of vanadium. Vanadium in leaching residue was probably in the form of vanadate or pyrovanadate of barium and calcium, which were hardly extracted during the sulfuric acid leaching process. The vanadium leaching kinetic analysis indicated that the leaching process was controlled by the diffusion through a product layer. The apparent activation energy could be achieved as 46.51 kJ/mol. The reaction order with respect to the sulfuric acid concentration was 1.1059. The kinetic model of vanadium recovery from stone coal using novel composite additive BaCO3/CaO could be finally established.

  20. 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

  1. Leaching Kinetics of Zinc from Metal Oxide Varistors (MOVs with Sulfuric Acid

    Directory of Open Access Journals (Sweden)

    Youngjin Kim

    2016-08-01

    Full Text Available The leaching kinetics of zinc from zinc oxide-based metal oxide varistors (MOVs was investigated in H2SO4 at atmospheric pressure. Kinetics experiments were carried out at various agitation speeds, particle sizes, initial H2SO4 concentrations, and reaction temperatures. It was determined that the leaching rate of zinc was independent of agitation speed above 300 rpm and also independent of particle size below 105 μm, whereas it dramatically increased with an increasing H2SO4 concentration. Except for when the H2SO4 concentration was varied, the m-values were almost constant at varying agitation speeds (m-values: 0.554–0.579, particle sizes (m-values: 0.507–0.560 and reaction temperature (m-values: 0.530–0.560 conditions. All of the m-values in these experiments were found to be below 0.580. Therefore, it is proposed that the extraction of zinc is a diffusion-controlled reaction. The leaching kinetics followed the D3 kinetic equation with a rate-controlling diffusion step through the ash layers, and the corresponding apparent activation energy was calculated as 20.7 kJ/mol in the temperature range of 313 K to 353 K.

  2. ACID RAIN - A PROBLEM OF THE PRESENT

    OpenAIRE

    Rozelinda Čož-Rakovac; Mato Hacmanjek; Zlatica Teskeredžić; Marija Tomec; Emin Teskeredžić; Šojat, V.; D Borovečki

    1995-01-01

    Acid rains is one of the most relevant problems of the human environment, the result being pollution of the atmosphere caused by ever growing industrial development. It is caused by the freeing of sulphuric oxides and oxygen, which along with certain chemical reactions transfer into sulphate and nitrate, and through wet or dry sediments reach the ground. This has an effect on lakes, rivers, the entire animal and plant kingdom, including all the good creations of mankind. Over a longer time pe...

  3. Recovery of Vanadium from H2SO4-HF Acidic Leaching Solution of Black Shale by Solvent Extraction and Precipitation

    Directory of Open Access Journals (Sweden)

    Xingbin Li

    2016-03-01

    Full Text Available The recovery of vanadium from sulfuric and hydrofluoric mixed acid solutions generated by the direct leaching of black shale was investigated using solvent extraction and precipitation methods. The process consisted of reduction, solvent extraction, and stripping, followed by precipitation and calcination to yield vanadium pentoxide. The influence of various operating parameters on the extraction and recovery of vanadium was studied. Vanadium (IV was selectively extracted using a mixture of 10% (v/v di(2-ethylhexylphosphoric acid and 5% (v/v tri-n-butylphosphate in sulfonated kerosene. Using six extraction and five stripping stages, the extraction efficiency for vanadium was 96.7% and the stripping efficiency was 99.7%. V2O5 with a purity of 99.52% was obtained by oxidation of the loaded strip solution and precipitation of ammonium polyvanadate at pH 1.8 to 2.2, followed by calcination of the dried precipitate at 550 °C for 2 h. It was concluded that the combination of solvent extraction and precipitation is an efficient method for the recovery of vanadium from a multi-element leach solution generated from black shale.

  4. Lead recovery and glass microspheres synthesis from waste CRT funnel glasses through carbon thermal reduction enhanced acid leaching process.

    Science.gov (United States)

    Mingfei, Xing; Yaping, Wang; Jun, Li; Hua, Xu

    2016-03-15

    In this study, a novel process for detoxification and reutilization of waste cathode ray tube (CRT) funnel glass was developed by carbon thermal reduction enhanced acid leaching process. The key to this process is removal of lead from the CRT funnel glass and synchronous preparation of glass microspheres. Carbon powder was used as an isolation agent and a reducing agent. Under the isolation of the carbon powder, the funnel glass powder was sintered into glass microspheres. In thermal reduction, PbO in the funnel glass was first reduced to elemental Pb by carbon monoxide and then located on the surface of glass microspheres which can be removed easily by acid leaching. Experimental results showed that temperature, carbon adding amount and holding time were the major parameters that controlled lead removal rate. The maximum lead removal rate was 94.80% and glass microspheres that measured 0.73-14.74μm were obtained successfully by setting the temperature, carbon adding amount and holding time at 1200°C, 10% and 30min, respectively. The prepared glass microspheres may be used as fillers in polymer materials and abrasive materials, among others. Accordingly, this study proposed a practical and economical process for detoxification and recycling of waste lead-containing glass. PMID:26642446

  5. Leaching studies for metals recovery from printed circuit boards scrap

    OpenAIRE

    Oliveira, Paula C.; Cabral, Marta; Taborda, F. Charters; Margarido, F.; Nogueira, C. A.

    2009-01-01

    In this paper, the leaching behavior of the major metals present in printed circuit boards waste is evaluated, aiming at its recycling by hydrometallurgy. Several leachants were compared (sulfuric, hydrochloric and nitric acids, at 2 M H+ concentration), at temperatures of 25ºC and 90ºC and 4 hours of reaction time. Sulfuric acid leaching was not very promising concerning metals dissolution being only effective for iron. Hydrochloric acid allowed the leaching up to 60% of tin and about 50% of...

  6. 用盐酸从锌烟尘中浸出铅锌试验研究%Leaching of Lead and Zinc From Zinc Dust Using Hydrochloric Acid

    Institute of Scientific and Technical Information of China (English)

    孙红燕; 森维; 孔馨; 李富宇

    2014-01-01

    研究了用盐酸从炼铅厂烟化段产出的锌烟尘中浸出分离铅和锌,考察了液固体积质量比、盐酸浓度、浸出温度和浸出时间对铅、锌浸出率的影响,确定了最佳浸出参数。试验结果表明:在浸出温度80℃、液固体积质量比8∶1、盐酸浓度6 mol/L最佳条件下,铅和锌的浸出率均大于90%。%Leaching of lead and zinc from zinc dusts coming from fuming stage in lead smelter were studied using hydrochloric acid .The effects the ratio between liquid volume and solid mass , concentration of acid ,leaching temperature and leaching time on zinc and lead leaching rates were examined .The results show that under the best conditions of the ratio between liquid volume and solid mass of 8∶1 ,leaching temperature of 80 ℃ and HCl concentration of 6 mol/L ,the leaching of lead and zinc are both more than 90% .

  7. Recovery of rare earths from acid leach solutions of spent nickel-metal hydride batteries using solvent extraction

    Institute of Scientific and Technical Information of China (English)

    夏允; 肖连生; 田吉英; 李兆洋; 曾理

    2015-01-01

    The extraction of rare earths from acid leach solutions of spent nickel-metal hydride batteries using a primary amine ex-tractant of N1923 was studied. The effects of feed pH, temperature, agitation rate and time on the extraction of rare earths, as well as stripping agent composition and concentration, phase ratio on the stripping were investigated. In addition, the extraction isotherm was determined. The pilot plant test results showed that the extraction of rare earths reached 99.98% after a five-stage counter current ex-traction. The mixed rare earths oxalates with the 99.77% purity of rare earth elements and impurity content less than 0.05% were ob-tained by the addition of oxalic acids in loaded strip liquors. The extractant exhibited good selectivity of rare earths over base metals of iron, nickel, copper and manganese.

  8. 黄铜矿硫化焙烧及氧压酸浸研究%Research on Oxygen Pressure Acid Leaching of Sulfidized Chalcopyrite

    Institute of Scientific and Technical Information of China (English)

    叶钟林; 施哲; 史谊峰; 张邦琪; 代红坤

    2014-01-01

    The special crystal structure of chalcopyrite makes it difficult to be leached in sulfuric acid system. Sulfidation roast process is studied in the present paper which transforms the chemical composition and structure of chalcopyrite into simple sulfides,which are more amenable to leaching.Both of the chalcopyrite and its sulfi-dation products are then leached for the extraction of copper in an appropriate leaching system.The results show that only covellite and pyrite could be found in the sulfidation product after being roasted for 60 min at 350 ℃which suggests nearly complete conversion of chalcopyrite.The leaching rate of copper from chalcopyrite and its sulfidation product,with leaching temperature of 150 ℃,time 120 min,oxygen partial pressure 0.5 MPa,stir-ring speed 700 r/min,and sulfuric acid 0.1 M,is 45% and 98%,respectively.The dissolve performance of chalcopyrite can be greatly improved by sulfidation roast.The results will provide theoretical instruction and tech-nological supports for industrializing application of chalcopyrite hydrometallurgy.%黄铜矿因其特殊的晶体结构在硫酸体系中较难溶解,采用硫化焙烧法使黄铜矿(CuFeS2)由复杂矿物组成及结构转变为易酸溶的简单硫化物(CuS,FeS2),并对黄铜矿及其硫化焙烧产物进行氧压酸浸对比实验研究.研究结果表明:350℃下黄铜矿与硫磺硫化焙烧60 min后,硫化焙烧反应进行的比较完全,焙烧产物中只有铜蓝CuS 和黄铁矿FeS2;当浸出温度为150℃、时间为120 min、氧分压为0.5 MPa、搅拌转速为700 r/min、木质磺酸钠为5 g/kg,液固比为7∶1,硫酸浓度为0.1 mol/L时,黄铜矿及硫化焙烧产物中铜的浸出率分别为45%和98%,经硫化焙烧后可显著改善黄铜矿在氧压酸浸过程中的溶解性能,为黄铜矿湿法冶炼工艺的工业化生产提供理论指导和技术支撑.

  9. 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...

  10. Two-stage precipitation process of iron and arsenic from acid leaching solutions

    Institute of Scientific and Technical Information of China (English)

    N.J.BOLIN; J.E.SUNDKVIST

    2008-01-01

    A leaching process for base metals recovery often generates considerable amounts of impurities such as iron and arsenic into the solution.It is a challenge to separate the non-valuable metals into manageable and stable waste products for final disposal,without loosing the valuable constituents.Boliden Mineral AB has patented a two-stage precipitation process that gives a very clean iron-arsenic precipitate by a minimum of coprecipitation of base metals.The obtained product shows to have good sedimentation and filtration properties,which makes it easy to recover the iron-arsenic depleted solution by filtration and washing of the precipitate.Continuos bench scale tests have been done,showing the excellent results achieved by the two-stage precipitation process.

  11. [Dynamic leaching behavior of heavy metals in eco-cement mortar block].

    Science.gov (United States)

    Li, Cheng; Liu, Jian-Guo; Zhang, Jun-Li; Yue, Dong-Bei; Nie, Yong-Feng; Wang, Chang-Hai

    2008-03-01

    A dynamic leaching test with the renewal of acidic leaching medium was designed to study the leaching behavior of the seven heavy metals (As, Cd, Cr, Cu, Ni, Pb, Zn) in three solidified eco-cement mortar samples with different particle size (fine granule, coarse granule, block) under a long-term leaching condition. It was demonstrated that all the heavy metals were detected in the leachate except Cd. The leaching ratio of Cr was the highest when compared with other metals in the same sample, and the leaching ratio of every metal showed an identical tendency: fine granule> coarse granule > block. The on-going leaching part of the relationship curve of accumulative leaching point (Pt) and t1/2 of each metal presented a fairly good linearity, which indicated that the leaching process was under the control of diffusion mechanism by the Fick Law. To each metal, the effective diffusion coefficient (Deff) showed a tendency of fine granule < coarse granule < block, which was opposite to the tendency of leaching ratio. It could be concluded that the solidified eco-cement mortar with a bigger size would have a lower leaching ratio and a shorter period to finish the leaching test. To all the metals, the Deff was very low, with the magnitude around 10(-10) cm2/s, which meant the leaching process would take a relatively long time. PMID:18649553

  12. Nutrient leaching potential following application of papermill lime-sludge to an acidic clay soil

    Directory of Open Access Journals (Sweden)

    S. C. Vettorazzo

    2001-09-01

    Full Text Available This experiment was carried out under greenhouse conditions with soil pots during 210 days, to evaluate the effect of calcitic papermill lime-sludge application (at the rates 0, 773, 1.547, and 2.320 mg kg-1 or respective equivalents to control, 2, 4, and 6 t ha-1, on chemical composition of soil leachate and its effects on eucalypt growth and yield. Highest soil leachate pH, SO4, and Na concentrations occurred in the 4 and 6 t ha-1 treatments. Soil leachate nitrate concentrations decreased with increasing lime-sludge rate. Soil leachate phosphate remained low (below the detection limit in all treatments until 120 days, while the concentration increased in the lime-sludge treatments at 210 days (last sampling in about 600 mg L-1. Lime-sludge decreased leachate Mg concentration, but had no significant effect among rates. Soil leachate Ca, K, B, Cu, Fe, and Zn did not change significantly for any lime-sludge application rates. The maximum NO3, Ca, Mg, K, and Na concentrations in the soil leachate occurred at 60 days after lime-sludge application (leaching equivalent to 1 pore volume, but for pH and SO4, the maximum occurred at 210 days (leaching equivalent to 4 pore volumes. Lime-sludge application decreased the concentration of exchangeable Al in the soil. Plant diameter growth and dry matter yield were increased with increasing lime-sludge rate. Beneficial effects on mineral nutrition (P, K, Ca, B, and Zn of eucalypts were also obtained by the application of 4 and 6 t ha-1 of lime-sludge.

  13. Study on leaching process of lead from acid residue%酸浸渣综合回收浸铅工艺研究

    Institute of Scientific and Technical Information of China (English)

    彭国敏; 俎小凤; 张福元

    2012-01-01

    In allusion to the comprehensive recovery of low-grade lead in acid residue from cyanidation process of golden leaching, salt leaching method was adopted to extract lead in the experimental study. Influences of the factors, such as liquid and solid (L/S) mass ratio, leaching temperature, leaching time, concentration of NaCl, and leaching pH, on leaching ratio of lead were studied through orthogonal experiment. It was found that when L/S mass ratio was 5, leaching tempeture was 333.15 K,mass fraction of NaCl was 30% ,pH =0,and leaching time was 4 h the best average lead leaching rate was 92.05% and relatively standard deviation was 4. 3‰. At room temperature, lead leaching rate also reached 90. 20% and relatively standard deviation was 4.1‰ So salt leaching method is an effective way of lead recovery and gold and silver yield improvement in comprehensive utilization of mines at room temperature.%针对氰化提金工艺酸浸渣中低品位金属铅的综合回收,采用盐浸法对金属铅进行了浸出实验研究,通过正交试验详细考察了浸出液固质量比、浸出温度、氯化钠浓度、浸出pH和浸出时间等因素对浸铅率的影响.结果表明,浸出液固质量比为5、浸出温度为333.15 K、氯化钠质量分数为30%、pH =0、浸出时间为4h的实验条件下,最佳平均浸铅率为92.05%,相对标准偏差RSD=4.3‰;室温下最佳平均浸铅率为90.20%,RSD =4.1‰.因此,酸浸渣常温盐浸提铅是综合利用矿产资源回收铅及提高金、银回收率的有效途径.

  14. Treatment of electronic waste to recover metal values using thermal plasma coupled with acid leaching – A response surface modeling approach

    International Nuclear Information System (INIS)

    Highlights: ► Sentences/phrases were modified. ► Necessary discussions for different figures were included. ► More discussion have been included on the flue gas analysis. ► Queries to both the reviewers have been given. - Abstract: The global crisis of the hazardous electronic waste (E-waste) is on the rise due to increasing usage and disposal of electronic devices. A process was developed to treat E-waste in an environmentally benign process. The process consisted of thermal plasma treatment followed by recovery of metal values through mineral acid leaching. In the thermal process, the E-waste was melted to recover the metal values as a metallic mixture. The metallic mixture was subjected to acid leaching in presence of depolarizer. The leached liquor mainly contained copper as the other elements like Al and Fe were mostly in alloy form as per the XRD and phase diagram studies. Response surface model was used to optimize the conditions for leaching. More than 90% leaching efficiency at room temperature was observed for Cu, Ni and Co with HCl as the solvent, whereas Fe and Al showed less than 40% efficiency.

  15. Kinetics of Mo, Ni, V and Al leaching from a spent hydrodesulphurization catalyst in a solution containing oxalic acid and hydrogen peroxide

    Energy Technology Data Exchange (ETDEWEB)

    Szymczycha-Madeja, Anna, E-mail: anna.szymczycha@pwr.wroc.pl [Chemistry Department, Analytical Chemistry Division, Wroclaw University of Technology, Wybrzeze Wyspianskiego 27, 50-370 Wroclaw (Poland)

    2011-02-28

    The kinetics of molybdenum, nickel, vanadium and aluminium leaching from a spent hydrodesulphurization catalyst in a solution containing oxalic acid and hydrogen peroxide was investigated. The effects of temperature and particle size were examined. In addition, the reaction mechanism for the dissolution of the spent catalyst was discussed. The results of the kinetic analysis for various experimental conditions indicated that the reaction rate of leaching process is controlled by chemical reaction at the particle surface. The values of the activation energies of 31 {+-} 2, 36 {+-} 4, 30 {+-} 4 and 57 {+-} 3 kJ mol{sup -1} for Mo, Ni, V and Al, respectively, are characteristic for mechanism controlled by chemical reaction.

  16. Selective Leaching of Zinc From Waste Alkaline Batteries Using Sulfuric Acid%用硫酸从废碱性电池中选择性浸出锌

    Institute of Scientific and Technical Information of China (English)

    易梦雨; 郎婷; 许东东; 孙维义; 丁桑岚; 苏仕军

    2014-01-01

    Spent alkaline zinc-manganese battery polar material mainly composes of manganese oxide , ZnO and graphite .Based on the different solubility of manganese oxides and ZnO in acid medium , sulfuric acid leaching of zinc is experimented to separate zinc and manganese .T he effect of the ratio between liquid volume and solid mass ,sulfuric acid concentration ,leaching time and leaching temperature on zinc and manganese leaching rate was investigated .The experimental results show that leaching rate of zinc and manganese reach 99% and 14% ,respectively at the conditions of leaching time of 1 h ,sulfuric acid concentration of 1 .0 mol/L ,the ratio between liquid volume and solid mass of 10 , temperature of 25 ℃ .T he XRD spectrum of leached residue show that zinc has been largely leached , the residues mainly contain graphite and manganese dioxide .%废碱性锌锰电池的极性材料主要由锰氧化物、ZnO和石墨组成。基于锰氧化物和ZnO在酸性介质中的溶解性差异,研究了用硫酸浸出锌,并实现锌、锰分离,考察了硫酸浓度、液固体积质量比、浸出时间、浸出温度对锌、锰浸出率的影响。结果表明:在硫酸浓度1.0 mol/L、液固体积质量比10∶1、反应时间1 h、温度25℃条件下,锰浸出率为14%,而锌浸出率达99%。浸出渣的XRD图谱表明,锌几乎完全浸出,剩余成分主要为石墨和二氧化锰。

  17. Recovery of tungsten from wolframite from the Igarape Manteiga mine (Rondonia - Brazil) via acidic leaching; Isolamento do tungstenio da volframita da mina de Igarape Manteiga (Rondonia - Brasil) por lixiviacao acida

    Energy Technology Data Exchange (ETDEWEB)

    Paulino, Jessica Frontino; Afonso, Julio Carlos [Departamento de Quimica Analitica, Instituto de Quimica, Universidade Federal do Rio de Janeiro, RJ (Brazil); Mantovano, Jose Luiz; Vianna, Claudio Augusto; Cunha, Jose Waldemar Silva Dias da [Instituto de Engenharia Nuclear (IEN/CNEN-RJ), Rio de Janeiro - RJ (Brazil)

    2012-07-01

    We report results of the efficiency of tungsten extraction from wolframite concentrate (containing 61.5 wt % WO{sub 3}) from the Igarape Manteiga mine (state of Rondonia, Brazil) through acid leaching with strong mineral acids at 100 deg C and 400 rpm for 2-4 h. HCl yielded insoluble matter containing the highest WO{sub 3} content (90 wt %). This solid was dissolved in concentrated NH{sub 3(aq)} at 25 deg C and the insoluble matter filtrated. The filtrate was slowly evaporated. 70 wt % of the tungsten present in the starting concentrate material was recovered as ammonium paratungstate (APT). (author)

  18. Manganese extraction from high-iron-content manganese oxide ores by selective reduction roasting-acid leaching process using black charcoal as reductant

    Institute of Scientific and Technical Information of China (English)

    张元波; 赵熠; 游志雄; 段道显; 李光辉; 姜涛

    2015-01-01

    Reduction roasting-acid leaching process was utilized to process high-iron-content manganese oxide ore using black charcoal as reductant. The results indicate that, compared with the traditional reductant of anthracite, higher manganese extraction efficiency is achieved at lower roasting temperature and shorter residence time. The effects of roasting parameters on the leaching efficiency of Mn and Fe were studied, and the optimal parameters are determined as follows: roasting temperature is 650 °C, residence time is 40 min, and black charcoal dosage is 10% (mass fraction). Under these conditions, the leaching efficiency of Mn reaches 82.37% while that of Fe is controlled below 7%. XRD results show that a majority of MnO2 and Fe2O3in the raw ore are reduced to MnO and Fe3O4, respectively.

  19. Combining Nitrilotriacetic Acid and Permeable Barriers for Enhanced Phytoextraction of Heavy Metals from Municipal Solid Waste Compost by and Reduced Metal Leaching.

    Science.gov (United States)

    Zhao, Shulan; Jia, Lina; Duo, Lian

    2016-05-01

    Phytoextraction has the potential to remove heavy metals from contaminated soil, and chelants can be used to improve the capabilities of phytoextraction. However, environmentally persistent chelants can cause metal leaching and groundwater pollution. A column experiment was conducted to evaluate the viability of biodegradable nitrilotriacetic acid (NTA) to increase the uptake of heavy metals (Cd, Cr, Ni, Pb, Cu, and Zn) by L. in municipal solid waste (MSW) compost and to evaluate the effect of two permeable barrier materials, bone meal and crab shell, on metal leaching. The application of NTA significantly increased the concentrations and uptake of heavy metals in . The enhancement was more pronounced at higher dosages of NTA. In the 15 mmol kg NTA treatment using a crab shell barrier, the Cr and Ni concentrations in the plant shoots increased by approximately 8- and 10-fold, respectively, relative to the control. However, the addition of NTA also caused significant heavy metal leaching from the MSW compost. Bone meal and crab shell barriers positioned between the compost and the subsoil were effective in preventing metal leaching down through the soil profile by the retention of metals in the barrier. The application of a biodegradable chelant and the use of permeable barriers is a viable form of enhanced phytoextraction to increase the removal of metals and to reduce possible leaching.

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

    Science.gov (United States)

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

    2015-11-01

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

  2. 用钛白废酸浸出赤泥的试验研究%Leaching of Red Mud Using Titanium White Waste Acid

    Institute of Scientific and Technical Information of China (English)

    樊艳金; 梁焕龙; 黄泰元; 张建飞; 郭旦奇

    2014-01-01

    研究了用钛白废酸从赤泥中浸出钪、钒、钛、硅,考察了钛白废酸浓度、反应时间、反应温度、液固体积质量比对各元素浸出率的影响。结果表明:随废酸浓度提高,元素浸出率提高,但溶液过滤性能变差;最佳浸出条件为废酸浓度1.6 mol/L ,反应时间40 min ,反应温度80℃,液固体积质量比4.5∶1。最佳条件下,钪、钛、钒、硅浸出率分别为62.12%、50.85%、40.56%和66.46%,溶液过滤性能良好。%Leaching of scandium ,titanium ,vanadium and silicium from red mud using titanium w hite waste acid as leaching agent was researched .The effect of titanium white waste acid concentration , reaction time ,reaction temperature ,the ratio between liquid volume and solid mass on leaching of scandium ,titanium ,vanadium and silicium were examined .The results show that the leaching of elements increase with concentration of titanium white waste acid ,but filtering performance of solution goes bad .At the optimal conditions of titanium white waste acid concentration of 1 .6 mol/L ,reaction time of 40 min ,reaction temperature of 80 ℃ ,the ratio between liquid volume and solid mass of 4 .5∶1 ,the leaching of scandium ,titanium ,vanadium and silicium are 62 .12% 、50 .85% 、40 .56% and 66 .46% ,respectively .

  3. [Dynamic leaching behavior of heavy metals in eco-cement mortar block].

    Science.gov (United States)

    Li, Cheng; Liu, Jian-Guo; Zhang, Jun-Li; Yue, Dong-Bei; Nie, Yong-Feng; Wang, Chang-Hai

    2008-03-01

    A dynamic leaching test with the renewal of acidic leaching medium was designed to study the leaching behavior of the seven heavy metals (As, Cd, Cr, Cu, Ni, Pb, Zn) in three solidified eco-cement mortar samples with different particle size (fine granule, coarse granule, block) under a long-term leaching condition. It was demonstrated that all the heavy metals were detected in the leachate except Cd. The leaching ratio of Cr was the highest when compared with other metals in the same sample, and the leaching ratio of every metal showed an identical tendency: fine granule> coarse granule > block. The on-going leaching part of the relationship curve of accumulative leaching point (Pt) and t1/2 of each metal presented a fairly good linearity, which indicated that the leaching process was under the control of diffusion mechanism by the Fick Law. To each metal, the effective diffusion coefficient (Deff) showed a tendency of fine granule mortar with a bigger size would have a lower leaching ratio and a shorter period to finish the leaching test. To all the metals, the Deff was very low, with the magnitude around 10(-10) cm2/s, which meant the leaching process would take a relatively long time.

  4. Catchment scale modelling of changes in pesticide leaching under present and future climate conditions. Demonstrated for two cases in Denmark

    Science.gov (United States)

    van der Keur, P.; Henriksen, H.; Sonnenborg, T.; van Roosmalen, L.; Rosenbom, A. E.; Olesen, J. E.; Kjaer, J.; Jørgensen, L. N.; Christensen, O. B.

    2011-12-01

    A catchment scale model MACRO-MIKE SHE is applied for simulating changes in pesticide concentrations to the aquatic environment. The MACRO model is used to model the effect of changes in climate and pesticide management on pesticide leaching from the unsaturated zone and simulated percolation as well as solute flow is propagated to the MIKE SHE model. The intensity based bias correction method for converting from Regional Climate Modelling data to hydrological input data is the most appropriate method as it best reflects changes in rainfall intensity, and thus also in intensity for MACRO simulated percolation and solute flow. Results show that increased percolation simulated by the MACRO model and propagated to the MIKE SHE model nearly all ends up in increased drainage to the river. Further, pesticide solute entering the saturated zone (SZ) is mainly leaving SZ via drainage (85-94%), base flow (3.8-11.3%) and overland flow (0-3.1 %). Mean concentrations in groundwater (SZ) increase by 30-99% for one type of herbicide under future climatic conditions, whereas mean concentrations decrease for two other types by app. 93 and 91 % respectively. Future climatic conditions lead to higher concentrations in surface water for the first type of herbicides, but to decreased concentrations for the another type of herbicide and insecticide. It is overall concluded that an integrated catchment scale modeling approach is essential for pesticide fate simulation taking account of all possible hydrologic pathways.

  5. Bacteria heap leaching test of a uranium ore

    International Nuclear Information System (INIS)

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

  6. Extraction of Alumina from high-silica bauxite by hydrochloric acid leaching using preliminary roasting method

    Science.gov (United States)

    Valeev, D. V.; Mansurova, E. R.; Bychinskii, V. A.; Chudnenko, K. V.

    2016-02-01

    A process of dissolution Severoonezhsk deposit boehmite-kaolinite bauxite by hydrochloric acid, as well as the processes that occur during open-air calcination, were investigated. A dehydration process has been studied, and the basic phase transformation temperatures were identified. Temperature and time of calcination influence on bauxite dehydration speed were determined. It is shown that the preliminary calcination increases the extraction ratio of alumina into solution up to 89%. Thermodynamic modelling of physical and chemical processes of bauxite decomposition by hydrochloric acid and the basic forms of aluminium speciation in solution were obtained.

  7. 高压酸浸法从镍红土矿中回收镍钴%Nickel and Cobalt Recovery from Laterite Type Nickel Ore with High Pressure Acid Leaching Technology

    Institute of Scientific and Technical Information of China (English)

    施洋

    2013-01-01

    Nickel and cobalt were recovered from Ramu laterite type nickel ore with high pressure acid leaching technology. The process introduced in detail includes slurry treatment, high pressure acid leaching (HPAL) , cycling leaching and slurry neutralization, CCD countercurrent washing, iron and aluminum removal with neutralization, precipitation of nickel hydroxide and cobalt hydroxide, deep sea tailings placement (DSTP). The problem presented in the process was investigated and improvement measurements were put forward. The recovery rate of nickel and cobalt are~96% and~94% respectively.%采用高压酸浸法从Ramu镍红土矿中回收镍钴.详细介绍了矿浆处理、高压酸浸、循环浸出及矿浆中和、CCD逆流洗涤、中和除铁铝、氢氧化镍钴沉淀、深海填埋工艺(DSTP)等流程,并分析了工艺出现的问题及改进措施.全流程镍回收率~96%,钴回收率~94%.

  8. 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.

  9. Leaching of organic acids from macromolecular organic matter by non-supercritical CO2

    Science.gov (United States)

    Sauer, P.; Glombitza, C.; Kallmeyer, J.

    2012-04-01

    The storage of CO2 in underground reservoirs is discussed controversly in the scientific literature. The worldwide search for suitable storage formations also considers coal-bearing strata. CO2 is already injected into seams for enhanced recovery of coal bed methane. However, the effects of increased CO2 concentration, especially on organic matter rich formations, are rarely investigated. The injected CO2 will dissolve in the pore water, causing a decrease in pH and resulting in acidic formation waters. Huge amounts of low molecular weight organic acids (LMWOAs) are chemically bound to the macromolecular matrix of sedimentary organic matter and may be liberated by hydrolysis, which is enhanced by the acidic porewater. Recent investigations outlined the importance of LMWOAs as a feedstock for microbial life in the subsurface [1]. Therefore, injection of CO2 into coal formations may result in enhanced nutrient supply for subsurface microbes. To investigate the effect of high concentrations of dissolved CO2 on the release of LMWOAs from coal we developed an inexpensive high-pressure high temperature system that allows manipulating the partial pressure of dissolved gases at pressures and temperatures up to 60 MPa and 120° C, respectively. In a reservoir vessel, gases are added to saturate the extraction medium to the desired level. Inside the extraction vessel hangs a flexible and inert PVDF sleeve (polyvinylidene fluoride, almost impermeable for gases), holding the sample and separating it from the pressure fluid. The flexibility of the sleeve allows for subsampling without loss of pressure. Coal samples from the DEBITS-1 well, Waikato Basin, NZ (R0 = 0.29, TOC = 30%). were extracted at 90° C and 5 MPa, either with pure or CO2-saturated water. Subsamples were taken at different time points during the extraction. The extracted LMWOAs such as formate, acetate and oxalate were analysed by ion chromatography. Yields of LMWOAs were higher with pure water than with CO2

  10. A perspective of stepwise utilisation of Bayer red mud: Step two--Extracting and recovering Ti from Ti-enriched tailing with acid leaching and precipitate flotation.

    Science.gov (United States)

    Huang, Yanfang; Chai, Wencui; Han, Guihong; Wang, Wenjuan; Yang, Shuzhen; Liu, Jiongtian

    2016-04-15

    The extraction and recovery of Ti from Ti-enriched tailing with acid leaching and precipitate flotation, as one of the critical steps, was proposed for the stepwise utilization of red mud. The factors influencing acid leaching and precipitate flotation were examined by factorial design. The leaching thermodynamics, kinetics of Ti(4+), Al(3+) and Fe(3+), and the mechanism of selectively Fe(3+) removal using [Hbet][Tf2N] as precipitating reagent were discussed. The extracting of Ti(4+), Al(3+) and Fe(3+) in concentrated H2SO4 is controlled by diffusion reactions, depending mainly upon leaching time and temperature. The maximum extracting efficiency of Ti(4+) is approximately 92.3%, whereas Al(3+) and Fe(3+) leaching are respectively 75.8% and 84.2%. [Hbet][Tf2N], as a precipitating reagent, operates through a coordination mechanism in flotation. The pH value is the key factor influencing the flotation recovery of Ti(4+), whereas the dosage of precipitating reagent is that for Al(3+) recovery. The maximum flotation recovery of Ti(4+) is 92.7%, whereas the maximum Al(3+) recovery is 93.5%. The total recovery rate for extracting and recovering titanium is 85.5%. The liquor with Ti(4+) of 15.5g/L, Al(3+) of 30.4g/L and Fe(3+) of 0.48g/L was obtained for the following hydrolysis step in the integrated process for red mud utilisation. PMID:26799223

  11. 二次酸浸法提取煤灰中的氧化铝%Aluminum extraction from coal ash by a two-step acid leaching method

    Institute of Scientific and Technical Information of China (English)

    Pei-wang ZHU; Hua DAI; Lei HAN; Xiu-lin XU; Le-ming CHENG; Qin-hui WANG; Zheng-lun SHI‡

    2015-01-01

    目的:煤灰渣酸浸提铝通常效率不高,主要因为灰渣中存在含铝晶体矿物(如莫来石、尖晶石和长石等)。为解决含铝晶体不易与硫酸反应的问题,本文提出二次酸浸提铝法。创新点:基本实现铝硅分离,第一步酸浸实现非晶态铝的浸出,残渣经焙烧和水浸后,第二步酸浸实现剩余铝的浸出。方法:1.一次酸浸时,硫酸直接与煤灰渣反应浸出部分氧化铝,提铝残渣加碳酸钠焙烧后,含铝晶体遭到破坏;2.焙烧产物经水浸溶解出硅酸钠,水浸残渣做X射线衍射分析表明其主要为铝硅非晶体活性物质,此时可用硫酸在温和条件下浸出剩余的铝。结论:1.一次酸浸提铝在10 mol/L硫酸、120°C、2 h和1:2固液比的条件下,铝浸出率为81.72%;2.用5 mol/L硫酸二次酸浸时,20°C下铝浸出率已经达到87.31%,100°C下更是达到99.06%;3.综合两次酸浸结果,铝的浸出总效率在97%以上。%To improve aluminum extraction efficiency, a two-step acid leaching process was proposed to dissolve aluminum and aluminum-bearing crystals with sulfuric acid. The first leaching residue (FLR) was obtained through direct leaching of coal ash with sulfuric acid. After roasting a mixture of the FLR and sodium carbonate, the aluminum-bearing crystals in FLR were com-pletely destroyed while sodium silicate was generated. Then the roasted products were leached with water to dissolve the sodium carbonate. X-ray diffraction (XRD) analysis indicated that the water leaching residues (WLR) mainly contained the amorphous phase, which allowed easy aluminum extraction in the second leaching step. In the first leaching test with 10 mol/L sulfuric acid at 120 °C in 2 h and a solid to liquid ratio (S/L) of 1:2, aluminum dissolution from raw coal ash reached 81.72%. In the second leaching step with 5 mol/L sulfuric acid, the aluminum dissolutions from WLR were 87.31% at 20 °C and 99.06% at 100

  12. Anti-reflection coatings applied by acid-leaching process. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Pastirik, E.

    1980-09-01

    The Magicote C process developed by S.M. Thompsen was evaluated for use in applying an antireflective coating to the cover plates of solar cell panels. The process uses a fluosilicic acid solution supersaturated with silica at elevated temperature to selectively attack the surface of soda-lime glass cover plates and alter the physical and chemical composition of a thin layer of glass. The altered glass layer constitutes an antireflective coating. The process produces coatings of excellent optical quality which possess outstanding resistance to soiling and staining. The coatings produced are not resistant to mechanical abrasion and are attacked to some extent by glass cleansers. Control of the filming process was found to be difficult.

  13. Comparative sorption and leaching study of the herbicides fluometuron and 4-chloro-2-methylphenoxyacetic acid (MCPA) in a soil amended with biochars and other sorbents

    OpenAIRE

    Cabrera Mesa, Alegría; Cox, L.; K. A. Spokas; Celis, R.; Hermosín, M. C.; Cornejo, J.; Koskinen, W. C.

    2011-01-01

    Biochar, the solid residual remaining after the thermochemical transformation of biomass for carbon sequestration, has been proposed to be used as a soil amendment, because of its agronomic benefits. The effect of amending soil with six biochars made from different feedstocks on the sorption and leaching of fluometuron and 4-chloro-2-methylphenoxyacetic acid (MCPA) was compared to the effect of other sorbents: an activated carbon, a Ca-rich Arizona montmorillonite modified with hexadecyltrime...

  14. 热酸浸出黄钾铁矾工艺的生产实践%Production Practice of Jarosite Process in Hot-acid Leaching

    Institute of Scientific and Technical Information of China (English)

    王顺才; 张豫

    2001-01-01

    介绍了热酸浸出黄钾铁矾工艺的生产实践,对氢氧化铁法和黄钾铁矾法两种除铁方法进行了比较。%This paper covers production practice of jarosite process in hot-acid leaching and comparison between iron hydroxide process and jarosite process that are used for iron removal.

  15. Direct Sulfuric Acid Leaching of A Lead-zinc Oxide Ore%氧化铅锌矿直接硫酸浸出

    Institute of Scientific and Technical Information of China (English)

    贺山明; 王吉坤; 李勇

    2011-01-01

    The direct sulfuric acid leaching process of lead-zinc oxide ore is investigated, and the impact factors on leaching are described. The results show that the more than 97% of zinc can be leached, more than 98% of lead into the slag, the rate of fluid production is greater than 162. 5L/m2 · H, the zinc content in residue is about 2. 5% and the lead content in residue is greater than 40% , under the optimal condition. The leaching residue can be sent to the lead smelting process.%探讨用硫酸直接浸出氧化铅锌矿,研究各种因素对浸出的影响.结果表明,在最佳工艺条件下,锌的浸出率可达97%以上,铅入渣率可达98%以上,产液速率大于162.5L/m2·h,渣含锌约2.5%,渣含铅量高达40%以上,浸出渣可送往炼铅系统处理.

  16. Effect of acid rain on mercury leaching from forest yellow soil in Jinyun Mountain%酸雨对缙云山林地黄壤汞溶出的影响

    Institute of Scientific and Technical Information of China (English)

    李静; 魏世强; 杨学春

    2004-01-01

    Forest yellow soil and arable yellow soil in Jinyun Mountain were collected to study the effect of simulated acid rain(adjusted to pH 2.0, 3.0, 4.0 and 5.0) on the Hg leaching from soils by the methods of static extraction and dynamic leaching. The results showed that in forest yellow soils, surface accumulation of Hg occurred, and the accumulated Hg was easier to be leached out than that in arable yellow soil by acid rain. The amount of leached Hg was the largest at pH 4.0. To abate the risk of Hg pollution in water bodies by the Hg leaching from this forest soil, the Mountain should be closed, and timber-felling should be forbidden.

  17. Kinetics study of leaching arsenic from Ni-Mo ore roasting in dust mixture of hydrochloric and sulfuric acids

    Institute of Scientific and Technical Information of China (English)

    侯晓川; 杨润德; 李贺; 曾理; 肖连生

    2014-01-01

    The kinetics of leaching arsenic from Ni-Mo ore roasting dust was investigated. The effects including leaching temperature, particle size of the smelter dust, stirring speed, the coefficientβ(the molar ratio of sodium chlorate to arsenic in the smelter dust) and the initial H+ concentration on leaching arsenic were studied. The results indicate that the leaching of arsenic increases sharply with the decrease of particle size. The orders of reaction with respect to H+ concentration and particle size are determinted to be 1.136 and-1.806, respectively.The leaching of arsenic reaches 99% under experimental conditions, the apparent activation energy is determined to be 11.157 kJ/mol, which is consistent with the values of activation energy for diffusion model. The kinetics equation of leaching arsenic from the roasting dust could be expressed by a semi-empirical equation as 1-2/3η-(1-η)2/3=k0(c[H+])1.136r0-1.806exp[(-11157/RT)t].

  18. Present and potential nitrogen outputs from Norwegian soft water lakes – an assessment made by applying the steady-state First-order Acidity Balance (FAB model

    Directory of Open Access Journals (Sweden)

    Ø. Kaste

    2002-01-01

    Full Text Available The steady-state First-order Acidity Balance (FAB model for calculating critical loads of sulphur (S and nitrogen (N is applied to 609 Norwegian soft-water lakes to assess the future nitrate (NO3‾ leaching potential under present (1992-96 S and N deposition. The lakes were separated into five groups receiving increasing levels of N deposition (-2yr-1. Using long-term sustainable N sink rates presently recommended for FAB model applications, N immobilisation, net N uptake in forests, denitrification and in-lake N retention were estimated for each group of lakes. Altogether, the long-term N sinks constituted 9.9 ± 3.2 to 40.5 ± 11.4 meq m-2yr-1 in the lowest and highest N deposition categories, respectively. At most sites, the current N deposition exceeds the amount of N retained by long-term sustainable N sinks plus the NO3‾ loss via the lake outlets. This excess N, which is currently retained within the catchments may, according to the FAB model, leach as acidifying NO3‾ in the future. If these predictions are fulfilled, NO3‾ leaching at sites in the various N deposition categories will increase dramatically from present (1995 mean levels of 1-20 meq m-2yr-1, to mean levels of 7-70 meq m-2yr-1 at future steady state. To illustrate the significance of such an increase in NO3‾ leaching, the mean Acid Neutralising Capacity (ANC at sites in the highest N deposition category may decrease from -18 ± 15 μeq L-1 at present, to -40 ± 20 μeq L-1. Under present S and N deposition levels, the FAB model predicts that 46% of the Norwegian lakes may experience exceedances of critical loads for acidifying deposition. In comparison, the Steady-State Water Chemistry model (SSWC, which considers only the present N leaching level, estimates critical load exceedances in 37% of the lakes under the same deposition level. Thus far, there are great uncertainties regarding both the time scales and the extent of future N leaching, and it is largely unknown

  19. Kinetics of Mo, Ni, V and Al leaching from a spent hydrodesulphurization catalyst in a solution containing oxalic acid and hydrogen peroxide.

    Science.gov (United States)

    Szymczycha-Madeja, Anna

    2011-02-28

    The kinetics of molybdenum, nickel, vanadium and aluminium leaching from a spent hydrodesulphurization catalyst in a solution containing oxalic acid and hydrogen peroxide was investigated. The effects of temperature and particle size were examined. In addition, the reaction mechanism for the dissolution of the spent catalyst was discussed. The results of the kinetic analysis for various experimental conditions indicated that the reaction rate of leaching process is controlled by chemical reaction at the particle surface. The values of the activation energies of 31±2, 36±4, 30±4 and 57±3 kJ mol(-1) for Mo, Ni, V and Al, respectively, are characteristic for mechanism controlled by chemical reaction. PMID:21167639

  20. On Sulfuric Acid Leaching in Magnetized Reduction of Zinc from Calcines%磁化还原焙砂硫酸浸出探索

    Institute of Scientific and Technical Information of China (English)

    曹子宇; 陈永明

    2015-01-01

    In order to address the problem of iron flowing into solution in profusion in the process of zinc reduction which causes environmental pollution,this paper conducts a systematic research into the process of sulfuric acid leaching in reducing zinc from calcines. By adopting single-factor conditional testing,this paper thoroughly investigates various factors that affect the sulfuric acid leaching including the initial acidity,liquid-solid ratio,temperature and duration. The optimized testing shows that under the optimized condition with the initial acidity of 120 g/L,at liquid-solid ratio of 7∶1,at a temperature of 60℃and in 2 hours the zinc leaching rate reaches 88.5%,the iron leaching rate 10.6% and the leached iron is almost totally ferrous iron. The result explains one step up to zinc calcine magnetized reduction of a reduction.%针对锌浸出过程中铁大量进入溶液,由此带来的环境污染问题,本研究对锌还原焙砂的硫酸浸出过程进行系统研究.采用单因素条件试验法,详细考察硫酸初始酸度、液固比、温度和时间对还原焙砂浸出过程的影响,并在最佳工艺条件下进行综合扩大试验.结果表明,在硫酸初始酸度120 g/L、液固比7∶1、温度60℃、时间2 h的优化条件下,锌的浸出率达到了88.5%,铁的浸出率为10.6%.浸出液中铁几乎全部为二价铁离子,表明对锌焙砂的磁化还原过还原了.

  1. Recovery of manganese and zinc from spent Zn-C cell powder: Experimental design of leaching by sulfuric acid solution containing glucose.

    Science.gov (United States)

    Biswas, Ranjit K; Karmakar, Aneek K; Kumar, Sree L

    2016-05-01

    The spent Zn-C cell powder, containing ZnMn2O4, ZnO, MnO(OH) and possibly Mn2O3 and Mn3O4, can be leached by a sulfuric acid solution mixed with some glucose. The leaching is found to be dependent on solid to liquid (S/L) ratio, amount of glucose, concentration of sulfuric acid solution, time and pulp agitation speed. For 5g powder (S), 1h leaching time and 300rpm pulp agitation speed, two-level four-factor (2(4)) experimental designs have been carried out to derive models for extraction of both Mn(II) and Zn(II). Amount of glucose (G, g), concentration of H2SO4 solution (C, mol/L), volume of H2SO4 solution as leachant (L, mL) and leaching temperature (T, °C) are considered as factors (variables). The model in both cases consists of mean, factor effects and interaction effects. The four-factor interaction effect is observed in neither of the cases. Some two-factor and three-factor effects are found to have produced positive or negative contributions to dissolution percentage in both cases. The models are examined for comparison with experimental results with good fits and also used for optimization of factors. At optimized condition (G=0.50g, C=2mol/L, L=250mL and T=100°C), an aliquot of 5g powder in 1h and at 300rpm produces a solution containing (7.08±0.10)g/L Mn(II) and (2.20±0.06)g/L Zn(II) corresponding to almost 100% extraction of both metal ions. PMID:26564257

  2. Leaching of Iron From Water-quenched Slag in Lead Smelting Using Sulfuric Acid%用硫酸从铅冶炼水淬渣中浸出铁的试验研究

    Institute of Scientific and Technical Information of China (English)

    孙红燕; 孔馨; 森维; 肖锐敏; 鲁顺利

    2015-01-01

    Leaching of iron from water‐quenched slag in lead smelting using sulfuric acid was researched .T he effects of sulfuric acid concentration ,leaching temperature and leaching time on leaching of iron were examined .The results show that under the optimum process conditions of sulfuric acid concentration of 175 g/L ,leaching temperature of 60 ℃ and leaching time of 60 min , leaching rate of iron is up to 73 .85% .%研究了用硫酸从铅冶炼水淬渣中浸出铁。考察了硫酸质量浓度、浸出温度、浸出时间对铁浸出率的影响。试验结果表明,用硫酸浸出铁,在硫酸质量浓度175 g/L、浸出温度60℃、浸出时间60 min最佳条件下,铁浸出率达73.85%。

  3. Uranium in situ leaching

    International Nuclear Information System (INIS)

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

  4. Gold leaching by organic base polythionates: new non-toxic and secure technology.

    Science.gov (United States)

    Smolyaninov, Vladislav; Shekhvatova, Galina; Vainshtein, Mikhail

    2014-01-01

    The article present a review on own experimental and some published data which are related with the gold leaching. It is well-known that the most common and usual process of the leaching with cyanide can be dangerous, needs a great water consumption, and additional costs for remediation of the poisoned and toxic sites. The experimental data described production of poythionates which are not toxic but perspective for the prosperous gold leaching. The paper dedicated to the safe gold leaching with thiosulfates and organic salts of polythionic acids (organic base polythionates). The method of production of these polythionates based on the Smolyaninov reaction is described in stages and in details for the first time. Possible application of the polythionates application in the gold leaching is discussed and its advantages are compared with the gold leaching by cyanation. PMID:24790825

  5. Temporal and spatial variation in the status of acid rivers and potential prevention methods of AS soil-related leaching in peatland forestry

    Energy Technology Data Exchange (ETDEWEB)

    Saarinen, T.

    2013-06-01

    This thesis examines temporal and spatial variations in the status of different rivers and streams of western Finland in terms of acidity and sources of acid load derived from the catchment area. It also examines the monitoring of acid runoff water derived from maintenance drainage in peatland forestry and suggests potential mitigation methods. A total of 17 river basins of different sizes in western Finland were selected for study, including rivers affected by both drainage of agricultural AS soils and forested peatlands. Old data from 1911-1931 were available, but most data were from the 1960s onwards and were taken from the HERTTA database. During 2009-2011, pH and conductivity measurements and water sampling were conducted. Biological monitoring for ecological classification was conducted in the Sanginjoki river system during 2008 and 2009. Three peatland forestry sites were selected to study acid leaching via pH and EC measurements and water sampling. Fluctuations in groundwater level in different drainage conditions were simulated and acid leaching was investigated in laboratory experiments in order to replicate a situation where the groundwater level drops and allows oxidation of sulphidic materials. It was found that river pH decreased and metal concentrations increased with runoff. The highest acidity observed coincided with periods of intense drainage in the 1970s and after dry summers in the past decade. Together with pH, electric conductivity and sulphate in river water were identified as suitable indicators of AS soils in a catchment, because they directly respond to acid leaching derived from AS soils. Acidity derived from organic acids was clearly observed in catchments dominated by forested peatlands and wetlands. Temporal and spatial variations in ecological status were observed, but monitoring at whole-catchment scale and during consecutive years is needed to increase the reliability of the results. Simulations on the potential effects of

  6. Recovery of zinc and manganese, and other metals (Fe, Cu, Ni, Co, Cd, Cr, Na, K) from Zn-MnO2 and Zn-C waste batteries: Hydroxyl and carbonate co-precipitation from solution after reducing acidic leaching with use of oxalic acid

    Science.gov (United States)

    Sobianowska-Turek, A.; Szczepaniak, W.; Maciejewski, P.; Gawlik-Kobylińska, M.

    2016-09-01

    The article discusses the current situation of the spent batteries and portable accumulators management. It reviews recycling technologies of the spent batteries and portable accumulators which are used in the manufacturing installations in the world. Also, it presents the authors' research results on the reductive acidic leaching of waste material of the zinc-carbon batteries (Zn-C) and zinc-manganese batteries (alkaline Zn-MnO2) delivered by a company dealing with mechanical treatment of this type of waste stream. The research data proved that the reductive acidic leaching (H2SO4 + C2H2O4) of the battery's black mass allows to recover 85.0% of zinc and 100% of manganese. Moreover, it was found that after the reductive acidic leaching it is possible to recover nearly 100% of manganese, iron, cadmium, and chromium, 98.0% of cobalt, 95.5% of zinc, and 85.0% of copper and nickel from the solution with carbonate method. On the basis of the results, it is possible to assume that the carbonate method can be used for the preparation of manganese-zinc ferrite.

  7. Measurement of leached hulls

    International Nuclear Information System (INIS)

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

  8. Oxidative leaching process with cupric ion in hydrochloric acid media for recovery of Pd and Rh from spent catalytic converters.

    Science.gov (United States)

    Nogueira, C A; Paiva, A P; Oliveira, P C; Costa, M C; da Costa, A M Rosa

    2014-08-15

    The recycling of platinum-group metals from wastes such as autocatalytic converters is getting growing attention due to the scarcity of these precious metals and the market pressure originated by increase of demand in current and emerging applications. Hydrometallurgical treatment of such wastes is an alternative way to the most usual pyrometallurgical processes based on smelter operations. This paper focuses on the development of a leaching process using cupric chloride as oxidising agent, in HCl media, for recovery of palladium and rhodium from a spent catalyst. The chloride media allows the adequate conditions for oxidising and solubilising the metals, as demonstrated by equilibrium calculations based on thermodynamic data. The experimental study of the leaching process revealed that Pd solubilisation is clearly easier than that of Rh. The factors temperature, time, and HCl and Cu(2+) concentrations were significant regarding Pd and Rh leaching, the latter requiring higher factor values to achieve the same results. Leaching yields of 95% Pd and 86% Rh were achieved under optimised conditions (T = 80 °C, t = 4h, [HCl] = 6M, [Cu(2+)] = 0.3M).

  9. 硫酸浸出电镀污泥中Zn、Cr条件及其动力学研究%Study on the Conditions and Kinetics on Sulfuric Acid Leaching Zinc and Chromium from Electro-plating Sludge

    Institute of Scientific and Technical Information of China (English)

    姚倩; 张宇峰; 葛苏苏; 汤传栋; 张慧

    2015-01-01

    采用硫酸作为酸浸出剂,考察了浸出时间、酸浓度和浸出温度对电镀污泥中重金属Zn、Cr浸出效果的影响,并运用Avrami方程拟合Zn、Cr的浸出动力学。结果表明:硫酸浸出Zn、Cr的最适浸出时间、酸浓度、温度均为4h、3mol/L、20℃。Zn、Cr的浸出过程均可用Avrami方程进行很好的拟合,其浸出反应的表观活化能分别为3.58和3.06kJ/mol,即两者的浸出过程均是扩散控制的,为工业规模的硫酸浸出电镀污泥中Zn、Cr提供理论参考。%This article,using sulphuric acid as acid leaching agent,investigates the effects of leaching time, acid concentration and leaching temperature on the leaching effect of zinc and chromium which are heavy metals from electroplating sludge,and uses Avrami equation to fit the leaching kinetics of zinc and chromi⁃um. The results showed that:both the optimum leaching time,acid concentration and temperature of sulph⁃uric acid leaching zinc and chromium are 4h,3mol/L and 20°C. Avrami equation could be used to fit both the leaching process of zinc and chromium very well,and the apparent activation energy of the leaching re⁃action are 3.58 and 3.06kJ/mol respectively,that is,both the leaching process are controlled by diffusion, which provides the theory reference for the sulfuric acid leaching zinc and chromium from electroplating sludge on an industrial scale.

  10. Electrochemistry of a semiconductor chalcopyrite concentrate leaching by Thiobacillus ferrooxidans

    Science.gov (United States)

    Torma, A. E.

    1991-05-01

    Using carbon-paste-CuFeS2 electrodes and a cyclic voltammetric technique, it was found that a large number of intermediate electrochemical oxidation reactions were associated with the dissolution of chalcopyrite in presence and absence of bacteria. The effects of concentrations of copper, ferrous and ferric ions, as well as of agitation on the peaks of cyclic voltammograms were measured. It was established that chalcopyrite oxidation was solid-state controlled as suggested by the data of chronopotentiometric and chronoamperometric measurements. The activation energy of solid state diffusion of chalcopyrite leaching was determined by the Sand's method to be delta E(sub a) = 20.5 kJ. The leaching mechanism is discussed in terms of solid-state properties (energy bonding) of the n-type semiconductor chalcopyrite and energy density states of redox systems of acidic bacterial leach media. A generalized model for the mechanism of chalcopyrite leaching in presence and absence of bacteria is presented.

  11. 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.

  12. 湿法炼锌净化渣酸浸的动力学%Acid leaching kinetics of zinc plant purification residue

    Institute of Scientific and Technical Information of China (English)

    李倩; 张宝; 闵小波; 申文前

    2013-01-01

    The leaching processes of zinc plant purification residue in sulfuric acid solution were investigated with respect to the effects of sulfuric acid concentration, reaction temperature, and particle size. A particle size of 75−80 μm was required to leach 99.8%cobalt and 91.97%zinc at 70 °C for 20 min when the sulfuric acid concentration was 100 g/L and the ratio of liquid to solid was 50׃1 (mL/g). The leaching kinetics of zinc plant purification residue in sulfuric acid solution system conformed well to the shrinking core model, and the dissolution rates of cobalt and zinc were found to be controlled by diffusion through a porous product layer. The apparent activation energy values of cobalt and zinc reaction were calculated to be 11.6931 kJ/mol and 6.6894 kJ/mol, respectively, according to the Arrhenius formula equation. The results show that diffusion through the inert particle pores is the leaching kinetics rate-controlling step.%对湿法炼锌净化渣的浸出动力学进行了研究,并探讨了硫酸浓度、反应温度、粒度等对钴、锌浸出率的影响规律。从动力学的角度分析了整个浸出过程,得到优化条件:液固比50:1(mL/g),硫酸浓度100 g/L,反应温度70°C,粒度75~80μm,反应时间20 min。在此优化条件下钴的浸出率为99.8%,锌的浸出率为91.97%。结果表明:在硫酸体系中钴的浸出符合不生成固体产物层的“未反应收缩核”模型。通过 Arrhenius 经验公式求得钴和锌表观反应活化能分别为11.693 kJ/mol和6.6894 kJ/mol,这表明浸出过程受边界层扩散控制。

  13. 铅反射炉含铟烟尘氧压酸浸的研究%Study on Oxygen Pressure Acid Leaching for Lead Reverberatory Furnace Indium Bearing Dust

    Institute of Scientific and Technical Information of China (English)

    李栋

    2012-01-01

    采用氧压酸浸技术对铅冶炼富铟烟尘进行浸出试验研究,详细考察了硫酸用量、氧分压、温度、液固比、时间、粒度等因素对铟浸出效果的影响,确定了氧压酸浸的最佳条件.结果表明,在下述最佳条件下:初始硫酸浓度180 g/L、氧分压0.8 MPa、温度150℃、液固比5∶1、时间120 min、反应物粒度0.15~0.12 mm,铟和锌的浸出率分别达到96.74%和99.19%,渣含铟小于0.02%.%Indium bearing dust from lead reverberatory furnace was leached with oxygen pressure acid leaching process. The effects of H2SO4 initial concentration, oxygen partial pressure, leaching temperature, ratio of liquid to solid (L/S), leaching time, and particle size of dust on the leaching were investigated, and the optimum conditions for oxidic-acidic pressure leaching were obtained. The results show that the leaching rate of indium and zinc reaches 96. 74% and 99, 19% respectively, and the content of indium in slag is reduced to less than 0. 02% under the optimum conditions including H2SO4 initial concentration of 180 g/L, oxygen partial pressure of 0. 8 MPa, leaching temperature of 150 ℃ , L/S of 5 : 1, leaching time of 120 min, and particle size of dust of 0- 15~0. 12 mm.

  14. 锑精炼除铅渣硝酸浸出回收铅的研究%Study on Lead Recovery from Lead Slag of Antimony Refining by Nitric Acid Leaching Process

    Institute of Scientific and Technical Information of China (English)

    韦岩松; 盘有旺

    2013-01-01

    采用硝酸浸出的方法从锑精炼除铅渣中回收金属铅,考察了液固比、浸出温度和时间、硝酸浓度等对铅浸出率的影响.结果表明,适宜的浸出工艺为:液固比4、浸出温度80℃、浸出时间50 min、硝酸浓度7.0 mol/L.在此条件下,铅浸出率可以达到94%.%Lead was recovered from lead slag of antimony refining by nitric acid leaching process.The effects of ratio of liquid to solid (L/S),leaching temperature and time,and nitric acid concentration on lead leaching rate were investigated.The results show that the lead leaching rate is above 94% under the optimum conditions including L/S of 4,leaching temperature of 80 ℃,leaching time of 50 min,and nitric acid concentration of 7.0 mol/L.

  15. 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.

  16. 刚果(金)氧化铜矿硫酸浸出的研究%Study on Sulfuric Acid Leaching of Oxidized Copper Ore f rom Congo (DRC)

    Institute of Scientific and Technical Information of China (English)

    李辉; 胡重; 刘岩

    2014-01-01

    研究了刚果(金)Shamitunba氧化铜矿的浸出过程。详细考察了矿石粒度、初始酸浓度、浸出温度、浸出时间、还原剂加入量及其它因素对铜和钴浸出率的影响。考察了浸出矿浆沉降、过滤和洗涤的效果。试验结果表明,在最佳试验条件下,铜、钴的浸出率分别为95.32%,41.99%。浸出液含铜4.47 g/L ,浸出液含钴0.032 g/L。%Leaching process of oxidized copper ore from Shamitunba in Congo(DRC)was studied .Influences of ore size 、initial acid concentration、leaching temperature、leaching time、dosage of reductant and others on the leaching rate of copper and cobalt were investigated in detail .Effect of settling 、filtration and washing of leaching pulp were examined . Experimental resalts indicated that the leaching rate of copper and cobalt is 95 .32% and 41 .99% respectively under the optimum conditions . The copper content in leaching solution is 4 .47 g/L ,and cobalt is 0 .032 g/L .

  17. Remediation of grey forest soils heavily polluted with heavy metals by means of their leaching at acidic pH followed by the soil reclamation by means of neutralization and bacterial manure addition

    Science.gov (United States)

    Georgiev, Plamen; Groudev, Stoyan; Spasova, Irena; Nicolova, Marina

    2014-05-01

    Some grey forest soils in Western Bulgaria are heavily polluted with heavy metals (copper, lead, and zinc), arsenic, and uranium due to the infiltration of acid mine drainage generated at the abandoned uranium mine Curilo. This paper presents some results from a study about soil remediation based on the contaminants leaching from the topsoil by means of irrigation with solutions containing sulphuric acid or its in situ generation by means of sulphur-oxidizing chemolithotrophic bacteria in or without the presence of finely cut straw. These methods were tested in large scale zero suction lysimeters. The approaches based on S° and finely cut straw addition was the most efficient amongst the tested methods and for seven months of soil remediation the concentration of all soil contaminants were decreased below the relevant Maximum Admissible Concentration (MAC). Neutralization of the soil acidity was applied as a next stage of soil reclamation by adding CaCO3 and cow manure. As a result, soil pH increased from strongly acidic (2.36) to slightly acidic (6.15) which allowed subsequent addition of humic acids and bacterial manure to the topsoil. The soil habitat changed in this way facilitated the growth of microorganisms which restored the biogeochemical cycles of nitrogen and carbon to the levels typical for non-polluted grey forest soil.

  18. 酸洗去除冶金硅中的典型杂质%Removal of representative impurities from metallurgical grade silicon by acid leaching

    Institute of Scientific and Technical Information of China (English)

    李成义; 赵立新; 王志; 郭占成; 王永刚

    2011-01-01

    以王水和氢氟酸为酸洗介质,研究酸洗对冶金硅中典型杂质元素的脱除效果.结果表明:王水和氢氟酸对金属类杂质均有明显的去除作用,但对非金属B和P去除效率差.Al杂质经王水和氢氟酸酸洗后去除率分别为80%和86.3%,Fe杂质的去除率分别为78.6%和89.4%.氢氟酸对总杂质去除率比王水提高12%,但其对Cu的去除率仅为4.8%.Cu的相态分析表明:Cu在冶金硅中主要是以Al-Si-Cu合金相存在,抗氢氟酸腐蚀性强.与氢氟酸不同,王水通过化学破碎作用使硅粉粒度变小,利于杂质相暴露.两种酸对硅粉的损失率均小于3.5%.%The removals of representative impurities by acid-leaching were studied using aqua regia and HF as the leaching acids. The results show that the two acids have obvious removal efficiency to metal impurities, but have little removal effect to B and P. After leaching, the removal rates of Al are 80% and 86.3% by aqua regia and HF, meanwhile, the removal rates of Fe are 78.6% and 89.4%, respectively. The total impurities removal rates after HF increase by 12% than that after aqua regia, but the removal efficiency of Cu by HF is very poor, with the removal rate reaches 4.8%. The structural phase analysis results show that Al-Si-Cu is the main existence form of Cu in metallurgical grade silicon (MG-Si), which is strong acid-resistance to HF. Unlike HF, the chemical stripping-off effect of the particle size of silicon powder made by aqua regia decreases obviously and the impurity phases easily expose at the grain boundaries. The loss rates of Si powder after two acids are less than 3.5%.

  19. Evaporation Behavior of Phosphorus from Metallurgical Grade Silicon via Calcium-Based Slag Treatment and Hydrochloric Acid Leaching

    Science.gov (United States)

    Huang, Liuqing; Lai, Huixian; Lu, Chenghao; Fang, Ming; Ma, Wenhui; Xing, Pengfei; Luo, Xuetao; Li, Jintang

    2016-01-01

    Phosphorus removal from metallurgical grade silicon by CaO-SiO2-CaCl2 slag treatment, HCl leaching, and vacuum refining was investigated. The effect of different compositions of slag was evaluated. The calcium concentration in slag-treated silicon increased with increasing CaO/SiO2 mass ratio of slag, decreasing the evaporation efficiency of phosphorus in molten silicon. The total phosphorus removal efficiency changed from 93.0% to 98.3% when the slag-treated silicon was treated with HCl before vacuum refining. The final concentration of phosphorus in silicon was 0.43 ppmw. This is because phosphorus was removed from metallurgical-grade silicon as follows: Phosphorus reacts with slag at the silicon/slag interface and forms Ca3(PO4)2 and Ca3P2, most of which diffuse from the interface to the slag phase. The remaining Ca3(PO4)2 and Ca3P2 reduce the phosphorus removal efficiency by altering the activity coefficient of phosphorus in molten silicon. HCl leaching enhanced the phosphorus removal efficiency by removing the remaining Ca3(PO4)2 and Ca3P2. Therefore, the mass transfer of phosphorus from metallurgical-grade silicon was accelerated.

  20. Alternative leaching processes for uranium ores

    International Nuclear Information System (INIS)

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

  1. Treatment of Fe(III) ions from leaching solutions with neutralisation and precipitation

    OpenAIRE

    Danovska, Milena; Golomeova, Mirjana; Karanfilov, Dejan; Zendelska, Afrodita

    2013-01-01

    The results of the study of leaching solutions (in the further text: productive solutions) from “BUCIM” mine treated with various neutralizing agents and combinations of two or a number of neutralizing agents are presented in this work. Leaching of copper with sulfuric acid is forwarded with the leaching of many other elements which are present in the ores. Among the elements is Fe (III) which abuses the Cu2+ Ions in further processing in production of cathode copper. The main objective o...

  2. Kinetics of titanium leaching with citric acid in sulfuric acid from red mud%柠檬酸助浸提取赤泥中钛的动力学

    Institute of Scientific and Technical Information of China (English)

    朱晓波; 李望; 管学茂

    2015-01-01

    The recovery of titanium with citric acid in sulfuric acid from red mud was put forward to strengthen acid leaching efficiency. The main factors on the recovery of titanium such as citric acid addition, sulfuric acid concentration, leaching temperature, time and liquid-to-solid ratio were studied. The kinetics analysis of titanium leaching from red mud was deeply investigated. The results show that the citric acid could increase the recovery of titanium and decrease the consumption of sulfuric acid. The recovery of titanium was increased from 65% to 82% and the consumption of sulfuric acid was decreased by about 30% with using 5% citric acid. The dissolution of perovskite, brookite, and hematite in red mud could easily be dissolved using citric acid. The acid leaching process was controlled by internal diffusion of shrinking core model (SCM) and the correlation coefficient was above 0.98. The apparent rate constant was increased from 0.0012 to 0.0019 with 5% citric acid at 90 ℃. The apparent activation energy of titanium leaching decreased from 39.77 kJ/mol to 34.61 kJ/mol with 5% citric acid.%在硫酸体系中,采用柠檬酸助浸提取赤泥中的钛,以提高钛的浸出效率.考察柠檬酸用量、硫酸浓度、浸出温度、反应时间和液固比等因素对钛浸出率的影响.研究赤泥浸出提钛过程的动力学理论.结果表明:在赤泥浸出过程中添加柠檬酸可显著提高钛的回收率和降低硫酸消耗.通过添加 5%的柠檬酸,钛的浸出率从 65%提高至82%,硫酸消耗降低30%,赤泥中的钙钛矿、板钛矿和赤铁矿更容易溶解溶出.动力学研究表明:赤泥助浸酸浸提钛过程受未反应收缩核模型的扩散步骤控制,线性相关系数大于 0.98.通过添加 5%的柠檬酸,可使赤泥酸浸提钛表观速率常数从0.0012提高至0.0019,表观活化能由39.77 kJ/mol降至 34.61 kJ/mol.

  3. Investigations into Recycling Zinc from Used Metal Oxide Varistors via pH Selective Leaching: Characterization, Leaching, and Residue Analysis.

    Science.gov (United States)

    Gutknecht, Toni; Gustafsson, Anna; Forsgren, Christer; Ekberg, Christian; Steenari, Britt-Marie

    2015-01-01

    Metal oxide varistors (MOVs) are a type of resistor with significantly nonlinear current-voltage characteristics commonly used in power lines to protect against overvoltages. If a proper recycling plan is developed MOVs can be an excellent source of secondary zinc because they contain over 90 weight percent zinc oxide. The oxides of antimony, bismuth, and to a lesser degree cobalt, manganese, and nickel are also present in varistors. Characterization of the MOV showed that cobalt, nickel, and manganese were not present in the varistor material at concentrations greater than one weight percent. This investigation determined whether a pH selective dissolution (leaching) process can be utilized as a starting point for hydrometallurgical recycling of the zinc in MOVs. This investigation showed it was possible to selectively leach zinc from the MOV without coleaching of bismuth and antimony by selecting a suitable pH, mainly higher than 3 for acids investigated. It was not possible to leach zinc without coleaching of manganese, cobalt, and nickel. It can be concluded from results obtained with the acids used, acetic, hydrochloric, nitric, and sulfuric, that sulfate leaching produced the most desirable results with respect to zinc leaching and it is also used extensively in industrial zinc production. PMID:26421313

  4. Investigations into Recycling Zinc from Used Metal Oxide Varistors via pH Selective Leaching: Characterization, Leaching, and Residue Analysis

    Directory of Open Access Journals (Sweden)

    Toni Gutknecht

    2015-01-01

    Full Text Available Metal oxide varistors (MOVs are a type of resistor with significantly nonlinear current-voltage characteristics commonly used in power lines to protect against overvoltages. If a proper recycling plan is developed MOVs can be an excellent source of secondary zinc because they contain over 90 weight percent zinc oxide. The oxides of antimony, bismuth, and to a lesser degree cobalt, manganese, and nickel are also present in varistors. Characterization of the MOV showed that cobalt, nickel, and manganese were not present in the varistor material at concentrations greater than one weight percent. This investigation determined whether a pH selective dissolution (leaching process can be utilized as a starting point for hydrometallurgical recycling of the zinc in MOVs. This investigation showed it was possible to selectively leach zinc from the MOV without coleaching of bismuth and antimony by selecting a suitable pH, mainly higher than 3 for acids investigated. It was not possible to leach zinc without coleaching of manganese, cobalt, and nickel. It can be concluded from results obtained with the acids used, acetic, hydrochloric, nitric, and sulfuric, that sulfate leaching produced the most desirable results with respect to zinc leaching and it is also used extensively in industrial zinc production.

  5. Leaching From Biomass Gasification Residues

    DEFF Research Database (Denmark)

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

    2011-01-01

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

  6. An efficient method combining thermal annealing and acid leaching for impurities removal from silica intended for photovoltaic application

    Indian Academy of Sciences (India)

    M Khalifa; M Hajji; H Ezzaouia

    2013-11-01

    This work investigates the photothermal treatment of silica sand to reduce impurities to a low level suitable for the production of acceptable solar grade silicon for photovoltaic application. It describes experiment carried out by using a tungsten lamp furnace to purify silica under controlled atmosphere. This process enables to attract impurities to the surface of silica grains where they can be easily extracted by partial dissolution in an acid mixture. Thus obtained silica was investigated by inductively coupled plasma atomic emission spectrometry (ICP–AES) method. Major impurities present in silica sand were Al, K, Fe, Na, Ca, Mg and B. Among the new products, almost major impurities were removed effectively. Indeed purity degree, given by characterization of ICP–AES, passes from 99.76 to 99.96% and the average impurity removal efficiency is 83.33%.

  7. 石煤微波空白焙烧-酸浸提钒工艺%Microwave roasting-acidic leaching technique for extraction of vanadium from stone coal

    Institute of Scientific and Technical Information of China (English)

    张小云; 覃文庆; 田学达; 陈燕波; 谷雨; 习晓光

    2011-01-01

    Compared with the conventional roasting-acidic leaching procedure and acidic leaching process of raw stone coal, the microwave roasting-acidic leaching technique for extraction of vanadium from stone coal was developed, and the effects of H2SO4 dosage and leaching time on vanadium extraction were investigated. The results show that the leaching rate of V2O5 reaches up to 83.5% when the tested sample is microwave roasted (without any additive) at 700 ℃for 60 min, the dosage of sulfuric acid is 22% of V2O5 leaching at 90 ℃. The leaching rate is improved by about 30%,more than that obtained from the conventional roasting or acidic leaching of raw stone coal under the same leaching conditions. The positive correlation between the leaching rate of V2O5 and Al2O3 is found out by leaching V2O5 and A12O3 from both the roasted samples and raw stone coal. Based on the minerals crystal constitution and the characteristics of microwave roast, the mechanism on improving the leaching rate of V2O5 by microwave roasting was discussed. It is indicated that the breakage of the minerals crystal constitution resulted from microwave roasting is the key factor of affecting the improvement of V2O5 leaching rate.%通过微波空白焙烧-酸浸提钒与传统加热焙烧一酸浸提钒和直接酸浸提钒的对比实验,考察H2SO用量和浸出时间对石煤中钒浸出的影响.结果表明:石煤在700℃下微波焙烧60 min,H2804用量为矿样质量的22%,浸出温度为90℃时,V2O浸出率达到83.50%,比传统加热焙烧一酸浸提钒和直接酸浸的浸出率提高约30%.通过对焙烧熟料酸浸和直接酸浸时Al2O3浸出率的分析发现,V2O浸出率与Al2O3浸出率呈正相关性.结合矿物晶体构造与微波加热原理,探讨了微波焙烧改善酸浸提钒的机理,认为微波焙烧可破坏含钒云母的晶体结构,是提高V2O浸出率的主要原因.

  8. Arachidonic acid needed in infant formula when docosahexaenoic acid is present.

    Science.gov (United States)

    Brenna, J Thomas

    2016-05-01

    Recently, the European Food Safety Authority asserted that arachidonic acid (ARA) is an optional nutrient for the term infant even when docosahexaenoic acid (DHA) is present. The brief rationale is based on an explicit, widespread misapplication of the concept of "essential fatty acids" to linoleic acid that implies it is uniquely required as a nutrient per se. Linoleic acid prevents acute clinical symptoms caused by polyunsaturated fatty acid-deficient diets and is the major precursor for ARA in most human diets. Experimental diets with ARA as the sole n-6 similarly prevent symptoms but at a lower energy percentage than linoleic acid and show ARA is a precursor for linoleic acid. The absence of consistent evidence of ARA benefit from randomized controlled trials is apparently an issue as well. This review highlights basic and clinical research relevant to ARA requirements as an adjunct to DHA in infancy. ARA is a major structural central nervous system component, where it rapidly accumulates perinatally and is required for signaling. Tracer studies show that ARA-fed infants derive about half of their total body ARA from dietary preformed ARA. Clinically, of the 3 cohorts of term infants studied with designs isolating the effects of ARA (DHA-only vs DHA+ARA), none considered ARA-specific outcomes such as vascular or immune function; the study with the highest ARA level showed significant neurocognitive benefit. All breastfed term infants of adequately nourished mothers consume both DHA and ARA. The burden of proof to substantially deviate from the composition of breastmilk is greater than that available from inherently empirical human randomized controlled trial evidence. Infant formulas with DHA but without ARA risk harm from suppression of ARA-mediated metabolism manifest among the many unstudied functions of ARA. PMID:27013482

  9. Method of continuous pressure leaching of ores

    International Nuclear Information System (INIS)

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

  10. 氧压酸浸低品位富银硫化矿富集提取银和锌%Silver and Zinc Recoveries by Acid Pressure Oxidative Leaching of Silver-bearing Lead-Zinc-Iron Sulfide Concentrate

    Institute of Scientific and Technical Information of China (English)

    梁铎强; 王吉坤; 汪云华

    2008-01-01

    The beneficiation of silver-bearing lead-zinc-iron sulfide concentrate from Yunnan Lancang Lead Ore Co.,Ltd is very difficult because of existence of great deal of pyrite and marcasite with content up to 70%,and the a-certain-extent oxidation of galena to yellow lead.In the present work,acid pressure oxidative leaching of such complex sulfide was investigated at the temperature ranging 90~170℃ to shed new light on the deportment of silver from the source concentrates to the residue with subsequent recovery by cyanidation.Lab-scale leaching experiments were conducted in a 2L autoclave to investigate the influences of temperature,acidity,sodium iodide usage,oxygen partial pressure,oxygen flow rate on the recoveries of silver and zinc.The results obtained show that the recovery of silver depends on whether the leached silver is incorporated into jarosite or convened into silver iodide by reaction with sodium iodide.Under optimum conditions,recoveries of silver and zinc can reach 71.5% and 41.29%,respectively.%由于含有大量的黄铁矿和白铁矿(它们约占原矿的70%,质量分数),以及闪铅矿一定程度上的氧化,云南澜沧铅矿股份有限公司所产的富银硫化矿难以富集.本文通过对该矿在90-170℃下氧压酸浸,以期连同后面的氰化能提取精矿中的银.通过进行2L高压釜的小型试验,考察了温度、酸度、碘化钠用量、氧分压、氧气流速对银和锌回收率的影响.结果表明,银的回收率取决于银是否进入黄钾铁矾渣,或者与碘化钠反应生成碘化银沉淀.在优化的条件下,银和锌的回收率分别达到71.5%和41.29%.

  11. 二氧化锰对石煤钒矿酸性浸出的影响%Effect of Manganese Dioxide on Acid Leaching of Vanadium from Stone Coal

    Institute of Scientific and Technical Information of China (English)

    颜文斌; 胡蓝双; 高峰; 华骏; 何新波

    2013-01-01

    采用湘西地区的石煤钒矿为研究对象,石煤中+3,+4,+5价钒分布分别为75.67%,17.85%和6.48%,硅酸盐含量较高,属高硅石煤矿.在传统直接酸浸工艺的基础上,添加少量氧化剂二氧化锰,考察了二氧化锰的用量、液固比、浸出温度、浸出时间、硫酸体积浓度等因素对钒浸出率的影响.单因素实验和正交试验结果表明:加入少量二氧化锰能协同H+破坏石煤结构,大大提高石煤中钒的浸出率;在二氧化锰用量为2%、液固比为1:1、浸出时间为13 h、硫酸体积浓度为25%和浸出温度为95℃的条件下,钒浸出率达到97.2%,其中硫酸体积浓度对石煤湿法提钒影响最大.和直接酸浸工艺相比,钒的浸出率提高40%以上;与传统的钠化焙烧工艺相比,钒的浸出率提高40%以上,完全消除了焙烧过程中所产生的烟气污染;本实验采用氧化酸浸提钒技术,不经焙烧过程,不产生烟气污染,节约能源,且能大幅度提高钒的浸出率,实现资源的充分利用,具有较好的应用前景.%The valence state distribution of +3, + 4, +5 V in stone coal from Xiangxi region were 75.67% 17. 85% and 6. 48% , respectively. Silicate content was higher, it belonged to high silica stone coal mine. Based on the traditional direct acid leaching technology, a small amount manganese dioxide as oxidant was added. Effects of manganese dioxide dosage, liquid-solid ratio, leaching temperature, leaching time, sulfuric acid volume concentration were investigated by single factor experiment and orthogonal test. The results showed that manganese dioxide could coordinate with hydrogen ions to damage the structure of the stone coal and increase significantly the leaching rate of vanadium, and the leaching rate could reach 97. 24% under the extraction conditions of oxidant dosage of 2% , liquid-solid ratio of 1: 1, leaching time of 13 h, sulfuric acid volume concentration of 25% , leaching temperature of 95

  12. 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.

  13. Nucleic acid therapy for lifespan prolongation: Present and future

    Indian Academy of Sciences (India)

    Wing-Fu Lai

    2011-09-01

    Lifespan prolongation is a common desire of the human race. With advances in biotechnology, the mechanism of aging has been gradually unraveled, laying the theoretical basis of nucleic acid therapy for lifespan prolongation. Regretfully, clinically applicable interventions do not exist without the efforts of converting theory into action, and it is the latter that has been far from adequately addressed at the moment. This was demonstrated by a database search on PubMed and Web of Science, from which only seven studies published between 2000 and 2010 were found to directly touch on the development of nucleic acid therapy for anti-aging and/or longevity enhancing purposes. In light of this, the objective of this article is to overview the current understanding of the intimate association between genes and longevity, and to bring the prospect of nucleic acid therapy for lifespan prolongation to light.

  14. Mineralogy and uranium leaching of ores from Triassic Peribaltic sandstones

    OpenAIRE

    Gajda, Dorota; Kiegiel, Katarzyna; Zakrzewska-Koltuniewicz, Grazyna; Chajduk, Ewelina; Bartosiewicz, Iwona; Wolkowicz, Stanislaw

    2014-01-01

    The recovery of uranium and other valuable metals from Polish Peribaltic sandstones were examined. The solid–liquid extraction is the first stage of the technology of uranium production and it is crucial for the next stages of processing. In the laboratory experiments uranium was leached with efficiencies 71–100 % by acidic lixiviants. Satisfactory results were obtained for the alkaline leaching process. Almost 100 % of uranium was leached with alkaline carbonate solution. In post leaching so...

  15. Reductive leaching of low-grade manganese ore with pre-processed cornstalk

    Science.gov (United States)

    Yi, Ai-fei; Wu, Meng-ni; Liu, Peng-wei; Feng, Ya-li; Li, Hao-ran

    2015-12-01

    Cornstalk is usually directly used as a reductant in reductive leaching manganese. However, low utilization of cornstalk makes low manganese dissolution ratio. In the research, pretreatment for cornstalk was proposed to improve manganese dissolution ratio. Cornstalk was preprocessed by a heated sulfuric acid solution (1.2 M of sulfuric acid concentration) for 10 min at 80°C. Thereafter, both the pretreated solution and the residue were used as a reductant for manganese leaching. This method not only exhibited superior activity for hydrolyzing cornstalk but also enhanced manganese dissolution. These effects were attributed to an increase in the amount of reductive sugars resulting from lignin hydrolysis. Through acid pretreatment for cornstalk, the manganese dissolution ratio was improved from 50.14% to 83.46%. The present work demonstrates for the first time the effective acid pretreatment of cornstalk to provide a cost-effective reductant for manganese leaching.

  16. Reductive leaching of low-grade manganese ore with pre-processed cornstalk

    Institute of Scientific and Technical Information of China (English)

    Ai-fei Yi; Meng-ni Wu; Peng-wei Liu; Ya-li Feng; Hao-ran Li

    2015-01-01

    Cornstalk is usually directly used as a reductant in reductive leaching manganese. However, low utilization of cornstalk makes low manganese dissolution ratio. In the research, pretreatment for cornstalk was proposed to improve manganese dissolution ratio. Cornstalk was preprocessed by a heated sulfuric acid solution (1.2 M of sulfuric acid concentration) for 10 min at 80°C. Thereafter, both the pretreated solu-tion and the residue were used as a reductant for manganese leaching. This method not only exhibited superior activity for hydrolyzing corn-stalk but also enhanced manganese dissolution. These effects were attributed to an increase in the amount of reductive sugars resulting from lignin hydrolysis. Through acid pretreatment for cornstalk, the manganese dissolution ratio was improved from 50.14%to 83.46%. The pre-sent work demonstrates for the first time the effective acid pretreatment of cornstalk to provide a cost-effective reductant for manganese leaching.

  17. Leaching and efficiency of six organic zinc fertilizers applied to navy bean crop grown in a weakly acidic soil of Spain.

    Science.gov (United States)

    Gonzalez, D; Novillo, J; Rico, M I; Alvarez, J M

    2008-05-14

    Zinc contamination of groundwater from fertilizers applied to pulse crops is a potential problem, but the use of different types of organic chelates can minimize the contamination potential while still adequately feeding the crops. The objective of this study was to compare the leaching, distribution in fractions and availability, and relative effectiveness of Zn from six organic Zn fertilizers (zinc-ethylenediaminetetraacetate- N-2-hydroxyethylethylenediaminetriacetate (Zn-EDTA-HEDTA), Zn-HEDTA, zinc- S, S'-ethylenediaminedisuccinate (Zn- S, S-EDDS), zinc-polyhydroxyphenylcarboxylate, Zn-EDTA, and zinc-ethylenediaminedi(2-hydroxy-5-sulfophenylacetate) (Zn-EDDHSA)) applied to a navy bean ( Phaseolus vulgaris, L.) crop cultivated by applying different Zn levels, in a weakly acidic soil under greenhouse conditions. Zinc soil behavior was evaluated by diethylenetriaminepentaacetic acid-triethanolamine (DTPA-TEA), DTPA-ammonium bicarbonate (DTPA-AB), Mehlich-3, and BaCl 2 extractions and sequential fractionation. In all the fertilizer treatments, the percentage of labile Zn that remained in the soil was high with respect to the quantity of Zn applied, with values respectively ranging from 42 to 80% for Zn-EDDHSA and Zn-EDTA sources. A positive correlation with a high level of significance existed between the micronutrient concentration in the navy bean crop (total and soluble) and labile Zn fractions, available Zn, and easily leachable Zn ( r ranged from 0.89 to 0.95, P < 0.0001). The relatively high quantity of total Zn leached by applying Zn-EDTA and Zn-S,S-EDDS sources (11.9 and 6.0%, respectively, for the rate 10 mg of Zn kg(-1) of soil) poses a potential pollution risk for neighboring waters. It would seem recommendable to apply Zn-HEDTA or Zn-EDDHSA sources, even applied at the low rate (5 mg of Zn kg(-1) of soil), because they produced available Zn concentrations in the soil that were above the critical concentration and also produced high Zn concentrations in

  18. Neptunium Colloidal Behaviors in Present of Humic Acids

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    <正>The colloidal-borne facilitated transport of actinides is an important part of radionuclide migration investigation in HLW geological disposal. In the present studies, Np colloidal behaviors in present of

  19. Aristolochic acid nephropathy: epidemiology, clinical presentation, and treatment.

    Science.gov (United States)

    Luciano, Randy L; Perazella, Mark A

    2015-01-01

    Aristolochic acid (AA) is a compound extracted from the Aristolochia species of herbs. It has been used for centuries as a remedy for various illnesses and diseases. However, in the early 1990s in the setting of a weight loss herbal remedy, AA exposure was associated with a syndrome of kidney injury, termed aristolochic acid nephropathy (AAN). This entity is marked by elevated serum creatinine, significant anemia, and histopathologic changes demonstrating a hypocellular interstitial infiltrate with severe fibrosis. Progression towards end-stage renal disease (ESRD) is rapid, with most patients having chronic kidney disease for less than 2 years. In addition, AAN is associated with a 40-45 % prevalence of urothelial carcinomas. Treatment of AAN is limited to glucocorticoids that have been shown to delay progression in non-randomized trials. As most patients progress to ESRD, need for renal replacement therapy, as either dialysis or kidney transplant, usually ensues. However, given the high malignant potential, care must be taken to minimize future development of upper urinary tract cancers by performing prophylactic bilateral nephroureterectomies and aggressive cancer surveillance. PMID:25446374

  20. Factors influencing leaching of uranium ore by organic acids from Aspergillus niger%黑曲霉产有机酸浸出铀矿石的影响因素

    Institute of Scientific and Technical Information of China (English)

    王永东; 李广悦; 丁德馨; 胡南; 邓钦文; 周支香

    2012-01-01

    Leaching uranium ores by fungi is a promising new bioleaching approach, and organic acids play key roles. However, little is known about the relationships between uranium leaching rate and organic acids produced by fungi. To explore the effects of medium types, culture temperature and pH value on uranium leaching by organic acids from Aspergillus niger, a strain of them was separated and purified from some water samples from a uranium mine. PSA and PCS medium were used for culture of Aspergillus niger, and mixed organic acids with different pH value produced by Aspergillus niger at diverse culture temperature were obtained and applied to tests of uranium leaching. The results show that leaching rate of uranium has statistically significant difference for these organic acids produced at different conditions, because there are different ingredients in these organic acids. All factors including of medium type, culture temperature and pH could influence composition and quantity of mixed organic acids. When Aspergillus niger was cultured in different medium, the composition of mixed organic acids is different, mainly oxalic acid and citric acid, and uranium leaching rates also different. Uranium leaching is better for the products obtained in PSA medium than in PCS one no matter different pH and culture temperature (p<0. 05). For same medium, due to difference in pH value culture temperature uranium leaching rate is also different (p<0.05). For example, for PSA the best culture temperature and pH value are 25℃ and 2.3 respectively, and mean uranium leaching rate were 76.14% and 82.40% at these conditions. While for PCS, the best conditions were 30℃ and 2.0, and the mean uranium leaching rate were 56.60% and 67.91%, respectively. The results also show that there are interaction effects between culture temperature and pH value of mixed organic acids (p<0. 05). Main factor influencing uranium leaching rate is pH value, and the second their interaction effects. Culture

  1. 钾长石活化焙烧-酸浸新工艺的研究%Research on the New Technology of Activated Roasting-Acid Leaching of Potash Feldspar

    Institute of Scientific and Technical Information of China (English)

    古映莹; 苏莎; 莫红兵; 徐文泱

    2012-01-01

    The new technology of activated roasting-acid leaching of potash feldspar in Xiangxi was researched in this paper. During the roasting process,by adding the low melting point potassium carbonate as flux,the potassium feldspar can be dissolved in the liquid state of the flux, which can increase the contact area and generate a com pound soluble in the acid medium. This made the degrading ability of potassium feldspar effectively improved. Dur ing the leaching process,the way that water leaching was followed by acid leaching was adopted. Because the roast ing itself is alkaline, the first water leaching could reduce the pH value, which can make subsequent leaching im prove the degrading rate of potassium feldspar without the change of acidity. In this experiment,during the coasting course, such factors which influenced the degrading rate as the material ration of flux and ore, roasting temperature and roasting time were investigated. During the course of leach course,such factors as the ration of liquid to solid, the concentration of sulfuric acid, leaching temperature and leaching time were investigated. The results showed when the mass ration of flux and otash feldspar was 0.7, the potash feldspar ore was roasted at 950T: about 1.5h, the achieved material was leached by 3mol/L about lh at room temperature and the ration of liquid to solid was 3: 1, the degrading rate of potash feldspar could reach 96%.%对湘西某钾长石矿进行了活化焙烧-酸浸新工艺的研究.在焙烧过程中,通过添加低熔点的碳酸钾作助熔剂,使钾长石的熔解在助熔剂的液体状态下进行,在增加反应的接触面积的同时生成了一种在酸性介质下易溶的化合物,从而有效的提高了钾长石的分解能力.在浸出过程中,采用了先水浸后酸浸的方式.由于焙炒本身呈碱性,先水浸有利于降低其pH值,使得后续的酸浸可在保持酸度不变的情况下提高钾长石的分解率.本试验主要考察了焙烧过程

  2. Zinc recovery from zinc calcine by selective reduction roasting and acid leaching%锌焙砂的选择性还原焙烧硫酸浸出工艺研究

    Institute of Scientific and Technical Information of China (English)

    侯栋科; 彭兵; 柴立元; 彭宁; 闫缓; 胡明

    2014-01-01

    Zinc recovery from zinc calcine containing high content of iron by selective reduction roasting and acid leaching was investigated. Zinc ferrite in zinc calcine was selectively transformed to zinc oxide and magnetite under CO and CO2 atmosphere. The reduced zinc calcine was then leached with sulfuric acid for dissolving the soluble zinc in the leaching solution and leaving the iron in the residue as magnetite. The effects of reaction parameters of reduction roasting and sulfuric acid leaching on the recovery of zinc were studied and the reduced sample was analyzed by chemical analysis, XRD and SEM-EDS. Using the content of soluble zinc and ferrous iron as the evaluation index of the reduction roasting, the optimum conditions were obtained as follows: roasting temperature (750 ℃), roasting time (60 min), CO concentration (8 %) and CO/(CO+CO2) ratio (20 %). Under the optimum conditions, the content of soluble zinc in zinc calcine increased from 79.64 % to 91.75 %. With the leaching efficiency of zinc and iron as the evaluation index of the acid leaching, the best leaching conditions were obtained as follows:leaching temperature (normal temperature), leaching time (30 min), sulfuric acid concentration (90 g/L) and liquid to solid ratio (10∶1). The leaching efficiency of zinc and iron under this condition is 91.8%and 7.17%, respectively.%研究了选择性还原焙烧-硫酸浸出两段工艺处理高铁锌焙砂的方法.首先在CO还原气氛下将锌焙砂中的铁酸锌选择性转化为氧化锌和磁铁矿,然后采用硫酸浸出使可溶锌溶出而铁存留于渣中,实现铁锌有效分离.主要考察了还原焙烧以及硫酸浸出的工艺条件对铁锌分离效果的影响,并采用化学分析法及XRD、SEM-EDS的检测手段对焙烧样品进行分析.以可溶性锌和亚铁的含量作为焙烧评价指标,得出最佳焙烧条件为:焙烧温度750℃,焙烧时间60 min,CO浓度8%,CO/(CO+CO2)气氛比例20%,此条件下

  3. Comparison of hot hydroxylamine hydrochloride and oxalic acid leaching of stream sediment and coated rock samples as anomaly enhancement techniques

    Science.gov (United States)

    Filipek, L.H.; Chao, T.T.; Theobald, P.K.

    1982-01-01

    A hot hydroxylamine hydrochloride (H-Hxl) extraction in 25% acetic acid is compared with the commonly used oxalic acid extraction as a method of anomaly enhancement for Cu and Zn in samples from two very different metal deposits and climatic environments. Results obtained on minus-80-mesh stream sediments from an area near the Magruder massive sulfide deposit in Lincoln County, Georgia, where the climate is humid subtropical, indicate that H-Hxl enhances the anomaly for Cu by a factor of 2 and for Zn by a factor of 1.5, compared to the oxalic method. Analyses of Fe oxide-coated rock samples from outcrops overlying the North Silver Bell porphyry copper deposit near Tucson, Arizona, where the climate is semi-arid to arid, indicate that both techniques effectively outline the zones of hydrothermal alteration. The H-Hxl extraction can also perform well in high-carbonate or high-clay environments, where other workers have suggested that oxalic acid is not very effective. Therefore, the H-Hxl method is recommended for general exploration use. ?? 1982.

  4. Phytanic acid alpha-oxidase deficiency (Refsum disease) presenting in infancy.

    Science.gov (United States)

    Herbert, M A; Clayton, P T

    1994-01-01

    This report describes a patient with high serum phytanic acid concentration due to phytanic acid alpha-oxidase deficiency (classical Refsum disease). He presented unusually early, hypotonia and developmental delay being apparent by 7 months. A generalized peroxisomal disorder (so-called 'infantile Refsum disease') was excluded by analyses of pristanic acid, very long-chain fatty acids, bile acids and plasmalogen synthesis. The early presentation raises the possibility of in utero exposure to phytanate.

  5. Recovering of Zinc ,Indium and Tin From Hard Zinc Slag by Alkaline-acid Cooperating Leaching%从硬锌渣中综合回收锌铟锡试验研究

    Institute of Scientific and Technical Information of China (English)

    戴兴征; 杨美彦; 陈凯; 曾鹏; 李永祥; 黄孟阳

    2015-01-01

    The process of neutral leaching zinc-concentrated sulfuric acid curing and water leaching indium-alkali leaching tin from a hard zinc slag produced from zinc pyromentallurgy was researched . The effects of hard zinc slag particle size ,ratio of liquid volume-to-solid mass and system acidity on leaching rate of zinc ,indium and tin w ere examined .T he results show that under the conditions of hard zinc slag particle size below 200 mesh ,ratio of liquid volume-to-solid mass of 4:1 ,and reaction ending pH of 5 .0-5 .5 ,leaching rate of zinc is 93% after reacting for 2 h at room temperature by neutral leaching .When curing for 4 h using concentrated sulfuric acid at the conditions of ratio of liquid volume-to-solid mass of 8:1 ,system acidity of 100 g/L then leaching for 4 h using water ,the leaching rate of indium reaches 99 .7% .When alkali leaching for 2 h at room temperature and ratio of liquid volume-to-solid mass of 3:1 with NaOH solution of 2 mol/L ,the leaching rate of tin is about 97% . Zinc ,indium and tin in the hard-zinc slag can be recovered effectively .%针对火法炼锌过程中产出的硬锌渣 ,研究了中性浸出锌—浓硫酸熟化水浸铟—碱浸锡 ,考察了物料粒度、液固体积质量比、体系酸度对锌、铟、锡浸出率的影响.结果表明 :在硬锌渣粒度小于200目、液固体积质量比4:1、反应终点p H为5 .0~5 .5、反应时间2 h、室温、中性浸出条件下 ,锌浸出率为93% ;在反应温度85℃ 、液固体积质量比8:1、体系酸度100 g/L、反应时间4 h条件下进行浓硫酸熟化浸出 ,铟浸出率达99 .7% ;在反应温度为室温、氢氧化钠浓度为2 mol/L、液固体积质量比3:1、反应时间2 h条件下进行碱浸 ,锡浸出率达97% .锌、铟、锡得到较好回收.

  6. Study on Leaching High Zn-Pb Dust from Rotary Hearth Furnace by Sulfuric Acid Solution%硫酸浸出转底炉高锌铅粉尘的研究

    Institute of Scientific and Technical Information of China (English)

    诸荣孙; 吴争; 伊廷锋; 夏征宇

    2012-01-01

    研究了硫酸浸出转底炉高锌铅粉尘提取锌的工艺条件和参数.最佳浸出工艺条件为:搅拌速度400 r/min,硫酸浓度为1.0mol/L,浸出温度为25℃,固液比为1∶8,浸出时间为0.5h.在此条件下,锌的浸出率可达96%以上.采用针铁矿-氧化水解法除铁、过硫酸铵深度除铁锰、锌粉置换除杂的方法对浸出液净化处理,得到高纯度硫酸锌溶液,该溶液可直接电解制取锌或制取碱式碳酸锌和氧化锌.%The technological conditions and parameters of leaching high Zn-Pb dust to extract Zn from rotary hearth furnace by sulfuric acid solution were studied. The optimum leaching conditions were obtained as follows; the stirring rate was 400 r/min, sulfuric acid concentration was 1.0 mol/L, the leaching temperature was 25 ℃ , the solid-liquid ratio was 1:8 and leaching time was 0. 5 h. Under these conditions, the leching rate of zinc can reach above 96%. Purification treatment was conducted for the leaching liquid, including using geothite and oxidation-hydrolysis process to remove iron, using ammonium persulphate to remove iron and manganese, using zinc powder to replace and remove impurities, thus high purity zinc sulfate solution was obtained, which can be used to prepare zinc or basic zinc carbonate and zinc oxide by direct electrolysis.

  7. Leaching and efficiency of six organic zinc fertilizers applied to navy bean crop grown in a weakly acidic soil of Spain.

    Science.gov (United States)

    Gonzalez, D; Novillo, J; Rico, M I; Alvarez, J M

    2008-05-14

    Zinc contamination of groundwater from fertilizers applied to pulse crops is a potential problem, but the use of different types of organic chelates can minimize the contamination potential while still adequately feeding the crops. The objective of this study was to compare the leaching, distribution in fractions and availability, and relative effectiveness of Zn from six organic Zn fertilizers (zinc-ethylenediaminetetraacetate- N-2-hydroxyethylethylenediaminetriacetate (Zn-EDTA-HEDTA), Zn-HEDTA, zinc- S, S'-ethylenediaminedisuccinate (Zn- S, S-EDDS), zinc-polyhydroxyphenylcarboxylate, Zn-EDTA, and zinc-ethylenediaminedi(2-hydroxy-5-sulfophenylacetate) (Zn-EDDHSA)) applied to a navy bean ( Phaseolus vulgaris, L.) crop cultivated by applying different Zn levels, in a weakly acidic soil under greenhouse conditions. Zinc soil behavior was evaluated by diethylenetriaminepentaacetic acid-triethanolamine (DTPA-TEA), DTPA-ammonium bicarbonate (DTPA-AB), Mehlich-3, and BaCl 2 extractions and sequential fractionation. In all the fertilizer treatments, the percentage of labile Zn that remained in the soil was high with respect to the quantity of Zn applied, with values respectively ranging from 42 to 80% for Zn-EDDHSA and Zn-EDTA sources. A positive correlation with a high level of significance existed between the micronutrient concentration in the navy bean crop (total and soluble) and labile Zn fractions, available Zn, and easily leachable Zn ( r ranged from 0.89 to 0.95, P EDDHSA sources, even applied at the low rate (5 mg of Zn kg(-1) of soil), because they produced available Zn concentrations in the soil that were above the critical concentration and also produced high Zn concentrations in plants (139 and 106 mg of Zn kg(-1) of dry matter, respectively). PMID:18402454

  8. Study of a bacterial leaching program for uranium ores by Thiobacillus ferroxidans

    International Nuclear Information System (INIS)

    The development of a bacterial leaching program for uranium ores is studied. Three basic points are presented: isolation and purification of Thiobacillus ferroxidans, as well Thiobacillus thio oxidans; physiological studies of growth and respiratory metabolism of T. ferroxidans; uranium leaching from two types of ore by T. ferroxidans action, on laboratory, semi pilot and pilot scales. The bacterial leaching studies were carried out in shake flasks, percolation columns (laboratory and semi pilot) and in heap leaching (pilot). The potential of the ores studied in relation to bacterial action, was first showed in shake flask experiments. The production of H2 S O4 and Fe3+ was a result of the bacterial activity on both ore samples containing pyrite (Fe S2). These two bacterial products resulted in a high uranium and molybdenum extraction and a lower sulfuric acid consumption compared to the sterilized treatments. Similar results were obtained in percolation column at the same scale (lab). (author)

  9. Oxalic-acid leaching of rock, soil, and stream-sediment samples as an anomaly-accentuated technique

    Science.gov (United States)

    Alminas, Henry V.; Mosier, Elwin L.

    1976-01-01

    In many instances total-rock and sieved-soil and stream-sediment samples lack the sensitivity and contrast required for reconnaissance exploration and necessary in the search for blind ore deposits. Heavy-mineral concentrates incorporate the required sensitivity and contrast but are overly expensive for two reasons: time-consuming sample preparation is required to obtain them, and they cannot be easily derived from all bulk-sample types. Trace-metal-content comparisons of the oxalic-acid-leachable portions with heavy-mineral concentrates show that the leachates are equal to the heavy-mineral concentrates in sensitivity and contrast. Simplicity of preparation and the resultant cost savings are additional advantages of this proposed method.

  10. 难处理铅锌矿酸浸渣回收硫酸铅的工艺研究%Study on recovery lead sulfate from complex acid leaching residue of lead-zinc mine

    Institute of Scientific and Technical Information of China (English)

    张传宝; 颜文斌; 徐辉; 高峰; 华骏

    2012-01-01

    The extraction process using sodium chloride and suliuric acid mixed solution, leaching lead from complex acid leaching residue of lead-zinc mine and preparing the lead sulfate by dilute leaching so lution. The influences of sodium chloride concentration,the liquid-solid ratio,time,temperature,acid concentration on lead leaching rate and diluted times,time on the lead sulfate precipitation was discussed. The results showed that the lead leaching rate of 82. 1% . when sodium chloride concentration of 330 g/L, sulfuric acid concentration of 1 mol/L,the liquid-solid ratio of 7: 1 at 95℃ for 1. 5 h, the purity of 99.1% products. The leaching solution in diluted times of 2.5 for standing time 7 h,lead sulfate precipitation rate was 93%. The lead recovery rate was 76% , it was improved by more than 30% compared with the traditional method.%采用氯化钠-硫酸混合溶液对铅锌矿难处理酸浸渣进行浸出,对浸出液稀释,制备硫酸铅,考察了氯化钠浓度、液固比、时间、温度和硫酸浓度等因素对酸浸渣的浸出影响和考察稀释倍数、时间等因素对沉淀硫酸铅的影响.结果表明,在氯化钠浓度为330 g/L,液固比为7:1,时间为1.5h,温度95℃,硫酸浓度为1mol/L的条件下,铅的浸出率为82.1%;在浸出液稀释倍数为2.5,静置时间7h的条件下,硫酸铅的沉淀率为93%,产品纯度为99.1%.铅的回收率为76%,比传统方法提高30%以上.

  11. 从闪速还原锌焙砂中选择性浸出锌、铁试验研究%Selective Acid Leaching of Zinc and Iron From Flash Reduction Zinc Calcine

    Institute of Scientific and Technical Information of China (English)

    戴曦; 陈田庄; 吴永谦; 周康洁; 李良斌

    2013-01-01

    Selective acid leaching of zinc and iron from flash reduction roasting product was studied .The influence of initial sulfuric acid concentration ,leaching temperature ,leaching time ,the ratio between liquid volume and solid mass ,stirring rate on leaching of zinc and iron were studied .The results show that the leaching rate of zinc increases more than 10% after zinc calcine being reduction roasted ,iron content in the leaching residue increases more than 7% .The leaching as well as filtering performance are improved due to the porous structure of reduction zinc calcine .The formation of the desired magnetic compound Fe3 O4 by efficient decomposition of ZnFe2 O4 in zinc calcine is effective to separate zinc and iron .%研究了从锌焙砂闪速还原焙烧产物中选择性酸浸锌,考察了初始硫酸质量浓度、浸出温度、浸出时间、液固体积质量比、搅拌速度对锌、铁浸出率的影响。试验结果表明:还原锌焙砂的锌浸出率较锌焙砂的锌浸出率提高10%以上,其浸出渣中含铁质量分数提高7%以上;还原锌焙砂结构疏松多孔,使其及浸出渣的过滤性能得以改善。高效分解锌焙砂中ZnFe2 O4并形成理想形态的磁性化合物Fe3 O4,是提高还原锌焙砂锌浸出率并抑制铁浸出从而实现锌、铁有效分离的关键。

  12. Cross-current leaching of indium from end-of-life LCD panels.

    Science.gov (United States)

    Rocchetti, Laura; Amato, Alessia; Fonti, Viviana; Ubaldini, Stefano; De Michelis, Ida; Kopacek, Bernd; Vegliò, Francesco; Beolchini, Francesca

    2015-08-01

    Indium is a critical element mainly produced as a by-product of zinc mining, and it is largely used in the production process of liquid crystal display (LCD) panels. End-of-life LCDs represent a possible source of indium in the field of urban mining. In the present paper, we apply, for the first time, cross-current leaching to mobilize indium from end-of-life LCD panels. We carried out a series of treatments to leach indium. The best leaching conditions for indium were 2M sulfuric acid at 80°C for 10min, which allowed us to completely mobilize indium. Taking into account the low content of indium in end-of-life LCDs, of about 100ppm, a single step of leaching is not cost-effective. We tested 6 steps of cross-current leaching: in the first step indium leaching was complete, whereas in the second step it was in the range of 85-90%, and with 6 steps it was about 50-55%. Indium concentration in the leachate was about 35mg/L after the first step of leaching, almost 2-fold at the second step and about 3-fold at the fifth step. Then, we hypothesized to scale up the process of cross-current leaching up to 10 steps, followed by cementation with zinc to recover indium. In this simulation, the process of indium recovery was advantageous from an economic and environmental point of view. Indeed, cross-current leaching allowed to concentrate indium, save reagents, and reduce the emission of CO2 (with 10 steps we assessed that the emission of about 90kg CO2-Eq. could be avoided) thanks to the recovery of indium. This new strategy represents a useful approach for secondary production of indium from waste LCD panels.

  13. Cross-current leaching of indium from end-of-life LCD panels.

    Science.gov (United States)

    Rocchetti, Laura; Amato, Alessia; Fonti, Viviana; Ubaldini, Stefano; De Michelis, Ida; Kopacek, Bernd; Vegliò, Francesco; Beolchini, Francesca

    2015-08-01

    Indium is a critical element mainly produced as a by-product of zinc mining, and it is largely used in the production process of liquid crystal display (LCD) panels. End-of-life LCDs represent a possible source of indium in the field of urban mining. In the present paper, we apply, for the first time, cross-current leaching to mobilize indium from end-of-life LCD panels. We carried out a series of treatments to leach indium. The best leaching conditions for indium were 2M sulfuric acid at 80°C for 10min, which allowed us to completely mobilize indium. Taking into account the low content of indium in end-of-life LCDs, of about 100ppm, a single step of leaching is not cost-effective. We tested 6 steps of cross-current leaching: in the first step indium leaching was complete, whereas in the second step it was in the range of 85-90%, and with 6 steps it was about 50-55%. Indium concentration in the leachate was about 35mg/L after the first step of leaching, almost 2-fold at the second step and about 3-fold at the fifth step. Then, we hypothesized to scale up the process of cross-current leaching up to 10 steps, followed by cementation with zinc to recover indium. In this simulation, the process of indium recovery was advantageous from an economic and environmental point of view. Indeed, cross-current leaching allowed to concentrate indium, save reagents, and reduce the emission of CO2 (with 10 steps we assessed that the emission of about 90kg CO2-Eq. could be avoided) thanks to the recovery of indium. This new strategy represents a useful approach for secondary production of indium from waste LCD panels. PMID:25997989

  14. Study on Recovering Copper and Zinc from Slag by Process of Acid Leaching and Solvent Extraction%酸浸-萃取法从炉渣中回收铜、锌的研究

    Institute of Scientific and Technical Information of China (English)

    刘缘缘; 黄自力; 秦庆伟

    2012-01-01

    以硫酸-双氧水浸出低品位炉渣,有效回收了铜和锌.分别进行了pH值、温度、双氧水用量对炉渣中铜锌浸出率的影响研究.研究结果表明:在常压条件下,当pH=2.5,浸出温度70℃,双氧水用量150 L/t时,炉渣中铜和锌的浸出率分别为54.77%和72.33%.用P204作萃取剂,硫酸作反萃剂,得到铜回收率为84.97%,锌回收率为96.47%.%Copper and zinc were effectively recovered by leaching low-grade slag with sulphate-hydrogen peroxide. The effects of pH value, leaching temperature and hydrogen peroxide dosage on leaching rate of copper and zinc were studied. Results showed that leaching rate of copper and zinc from slag reached 54. 77% and 72. 33% , respectively, under normal atmospheric pressure, at a leaching temperature of 70 ℃ , with pH value of 2. 5 and hydrogen peroxide dosage of 150 L/t. The recovery of copper and zinc was 84.97% and 96.47% , respectively, by using P204 as extractant and sulfuric acid as stripping agent.

  15. 石棉尾矿酸浸渣填充改性道路沥青的研究%Research on Road Asphalt Filled and Modified with Acid-leaching Residue of Asbestos Tailings

    Institute of Scientific and Technical Information of China (English)

    孙志明; 郑水林; 文明; 吴照洋

    2009-01-01

    The acid-leaching residue of asbestos tailings is silicon slag of asbestos tailings, one kind of solid waste after acid leaching extraction of magnesium. In this experiment, using acid leaching residue of asbestos tailings after calcination as the filler of asphalt modifier, through the test of penetration, ductility, softening point of modified asphalt, the effects of the adding volume and mixing conditions (temperature, time, etc.) of the acid leaching residue on the performance of road asphalt has been studied. The results showed that the appropriate conditions of modified process is that the adding volume of acid leaching residue 6%, mixing temperature 140℃, and heating mixing time 20rain. In this condition, the performance of modified asphalt material, such as high temperature and low temperature performance, temperature sensitivity, and anti-aging property have been significantly improved.%石棉尾矿酸浸渣是石棉尾矿蛇纹石酸浸提取氧化镁后的硅质粉体材料.本实验以煅烧后的石棉尾矿酸浸渣作为道路沥青填充改性剂,通过测定改性沥青的针入度、延度、软化点等指标,研究了酸浸渣填充量、混合控温以及加热混合时间对道路沥青综合性能的影响.结果表明,石棉尾矿酸浸渣填充改性沥青适宜的填充工艺条件为填充量6%,混合控温140℃,加热混合时间20min;在适宜的填充工艺条件下,改性沥青的高温性能、低温性能、高低温稳定性以及抗老化性均得到显著改善或提高.

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

    Institute of Scientific and Technical Information of China (English)

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

    2007-01-01

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

  17. Oxygen Pressure Acid Leaching Synthetic Reclaiming of Complex Cu -Pb Bulk Concentrate%复杂铜铅混合精矿氧压浸出综合回收工艺

    Institute of Scientific and Technical Information of China (English)

    杨俊奎; 徐斌; 杨大锦; 钟宏; 姜涛

    2011-01-01

    The main copper and lead minerals in complex Cu - Pb bulk concentrate from Sichuan province of China are tetrahedrite and galena, and there are also abundant Pb, Zn, Fe, As and Sb in the concentrate. The concentrate is treated by oxygen pressure acid leaching synthetic reclaiming technique. The best technology conditions are obtained by experiments. It is concluded through the enlarged experiment that the leaching rates of copper and zinc are 98.89% and 94.92% respectively, and that the elements of Pb and Ag transform into sulfate and sulfid depositions. The abruption between Cu, Zn and Pb, Ag is complete. Copper and Zinc are reclaimed with the method of extraction and electrolyse. While lead and silver in the leaching residue are reclaimed through the translation of carbonate first, and then leaching Pb with silicofluoric acid and leaching Ag with thiourea at the last. The extraction rate of copper, leaching rate of lead and silver are 96%, 94% and 93% respectively.%呷村铜铅混合精矿中铜、铅矿物主要为黝铜矿和方铅矿,还含有较高的锌、银、砷和锑.本试验针对该矿采用一段氧压浸出综合回收工艺进行处理,通过条件优化实验确定了氧压浸出的操作条件.扩大验证实验表明Cu、Zn的浸出率分别高达98.89%、94.92%,Pb、Ag转化为矾类和硫化物形式留在浸出渣中,铜锌与铅银分离彻底.浸出液中的铜、锌分别通过萃取、电积进行回收.浸出渣中的铅、银通过碳酸盐转化-硅氟酸浸铅-硫脲浸银进行回收.铜萃取率,铅、银浸出率分别为96%、94%和93%.

  18. 从酸浸渣中综合回收金银铁铅的试验研究%Experimental research on comprehensive recovery of gold, Chinese silver,iron and lead from acid leaching slag

    Institute of Scientific and Technical Information of China (English)

    薛元昕; 薛光

    2011-01-01

    对从酸浸渣中综合回收金银铁铅进行了试验研究.试验结果表明,采用试验确定的工艺方法,不但可回收酸浸渣中铁铅,还可提高金银的氰化浸出率,分别可达98 %和70 %以上,能获得较好的经济效益和社会效益.%Experimental study is carried out on comprehensive recovery of gold, silver, iron and lead from acid leaching slag. The tests show that with the technology, not only the iron and lead can be recovered, but also the cyanide leaching rate of gold and silver can be enhanced, which is respectively up to 98 % and 70 %. Good economic and social benefits can be obtained.

  19. MODEL FOR PREDICTING THE INITIAL SOLUTION pH AT PRE-ASSUMED FINAL pH AND CONCENTRATION OF DISSOLVED LEAD DURING LEACHING OF GALENA IN BUTANOIC ACID SOLUTION

    Directory of Open Access Journals (Sweden)

    C. I. NWOYE

    2010-06-01

    Full Text Available Model for predicting the initial solution pH at pre-assumed final pH and concentration of dissolved lead, during leaching of galena in butanoic acid solution has been derived. The model shows that the initial pH of the leaching is dependent on the values of the pre-assumed final solution pH and concentration of dissolved lead. The validity of the model was rooted in the expression e^(Nγ/α=∛Pb where both sides of the expression were approximately equal to 5. The maximum deviation of the model-predicted initial solution pH value from that of the corresponding experimental value was less than 3% which is quite within the acceptable deviation limit of experimental results.

  20. Reductive leaching of manganese oxide ores using waste tea as reductant in sulfuric acid solution%以废茶叶为还原剂在硫酸溶液中还原浸出氧化锰矿

    Institute of Scientific and Technical Information of China (English)

    唐清; 钟宏; 王帅; 李进中; 刘广义

    2014-01-01

    Manganese oxide ores from Gabon and Xiangxi were leached with waste tea as reductant in dilute sulfuric acid solution. The effects of waste tea dosage, concentration of sulfuric acid, liquid-to-solid ratio, leaching temperature and reaction time on leaching process were explored. The leaching efficiency of Gabonese manganese oxide ore reached almost 100%under the optimal condition which was determined as follows:manganese oxide ore to waste tea mass ratio of 10:1, sulfuric acid concentration of 2.5 mol/L, liquid-to-solid ratio of 7.5:1, leaching temperature of 368 K, time of 8 h. The leaching efficiency of Xiangxi manganese oxide ore reached 99.8%under the optimal condition which was determined as follows:manganese oxide ore to waste tea mass ratio of 10:1, sulfuric acid concentration of 1.7 mol/L, liquid-to-solid ratio of 7.5:1, leaching temperature of 368 K, time of 8 h. The leaching process followed the internal diffusion controlled kinetic model, and the apparent activation energies of Gabonese manganese oxide ore and Xiangxi manganese oxide ore were calculated to be 38.2 kJ/mol and 20.4 kJ/mol, respectively. The morphological changes and mineralogical forms of the ore before and after the chemical treatment were discussed with the support of XRD analysis and SEM analysis.%采用废茶叶在硫酸溶液中还原浸出加蓬和湘西氧化锰矿石,探索废茶叶用量、硫酸浓度、固液比、浸出温度和反应时间对浸出过程的影响。对加蓬氧化锰矿,优化的浸出条件为:氧化锰矿与废茶叶的质量比10:4、硫酸浓度2.5 mol/L、固液比7.5:1、浸出温度368 K、浸出时间8 h;在此条件下,加蓬氧化锰矿的浸出率几乎达100%。对于湘西氧化锰矿,优化浸出条件为:氧化锰矿与废茶叶的质量比10:1、硫酸浓度1.7 mol/L、液固比7.5:1、温度368 K、浸出时间8 h;在此条件下,锰的浸出率达到99.8%。氧化锰矿的还原浸出过程符合内扩散控制模

  1. Effect of peroxodisulfate on uranium leaching with ammonium bicarbonate

    Directory of Open Access Journals (Sweden)

    Nurbek Nurpeisov

    2013-05-01

    Full Text Available In this study, uranium leaching from ore material using acid solution and bicarbonate in a presence peroxodisulfate ion was examined. For experiments two different tips of leaching methods were used: leaching in static and dynamic conditions. The determination of uranium concentrations in product solutions were analyzed by titrimetric (by ammonia vanadate solution method. The maximum yield of uranium leached with ammonium bicarbonate in a presence of ammonium peroxodisulfate (5 g/L was only 33%, which is half the corresponding value obtained by sulfuric acid (65%.

  2. Past and Present Insights on Alpha-linolenic Acid and the Omega-3 Fatty Acid Family.

    Science.gov (United States)

    Stark, Aliza H; Reifen, Ram; Crawford, Michael A

    2016-10-25

    Alpha-linolenic acid (ALA) is the parent essential fatty acid of the omega-3 family. This family includes docosahexaenoic acid (DHA), which has been conserved in neural signaling systems in the cephalopods, fish, amphibian, reptiles, birds, mammals, primates, and humans. This extreme conservation, in spite of wide genomic changes of over 500 million years, testifies to the uniqueness of this molecule in the brain and affirms the importance of omega-3 fatty acids. While DHA and its close precursor, eicosapentaenoic acids (EPA), have received much attention by the research community, ALA, as the precursor of both, has been considered of little interest. There are many papers on ALA requirements in experimental animals. Unlike humans, rats and mice can readily convert ALA to EPA and DHA, so it is unclear whether the effect is solely due to the conversion products or to ALA itself. The intrinsic role of ALA has yet to be defined. This paper will discuss both recent and historical findings related to this distinctive group of fatty acids, and will highlight the physiological significance of the omega-3 family. PMID:25774650

  3. Comparision of Different Reductants in Leaching of Spent Lithium Ion Batteries

    Science.gov (United States)

    Meshram, Pratima; Abhilash; Pandey, Banshi Dhar; Mankhand, Tilak Raj; Deveci, Haci

    2016-10-01

    The present work focuses on the processing of cathode active material of spent lithium ion batteries to improve the recovery of constituent metals using reducing agents. Reductants enhance the solubility of metals, which hitherto have been solubilised to a lesser extent using only acid as leaching agent. Thus, we have investigated sulfuric acid leaching in the presence of sodium bisulfite comparing its efficiency with hydrogen peroxide. By simple acid leaching using 1 M H2SO4 at 368 K and 50 g/L pulp density, 93.4% Li, 66.2% Co, 96.3% Ni and 50.2% Mn were recovered in 240 min. In the presence of 5% H2O2 as a reducing agent at 368 K with 1 M H2SO4 and 50 g/L pulp density, the leaching of cobalt (79.2%) and manganese (84.6%) were significantly improved in 240 min. With the addition of 0.075 M NaHSO3 as a reducing agent, ~96.7% Li, 91.6% Co, 96.4% Ni and 87.9% Mn were recovered under similar conditions. Sodium bisulfite addition results in better recovery of cobalt and manganese by reducing them to their lower oxidation states. The HSC evaluation of thermodynamic feasibility vis-à-vis x-ray diffraction and scanning electron microscopy characterization of residues generated by leaching with hydrogen peroxide and sodium bisulfite substantiates the governing mechanism.

  4. Comparision of Different Reductants in Leaching of Spent Lithium Ion Batteries

    Science.gov (United States)

    Meshram, Pratima; Abhilash; Pandey, Banshi Dhar; Mankhand, Tilak Raj; Deveci, Haci

    2016-07-01

    The present work focuses on the processing of cathode active material of spent lithium ion batteries to improve the recovery of constituent metals using reducing agents. Reductants enhance the solubility of metals, which hitherto have been solubilised to a lesser extent using only acid as leaching agent. Thus, we have investigated sulfuric acid leaching in the presence of sodium bisulfite comparing its efficiency with hydrogen peroxide. By simple acid leaching using 1 M H2SO4 at 368 K and 50 g/L pulp density, 93.4% Li, 66.2% Co, 96.3% Ni and 50.2% Mn were recovered in 240 min. In the presence of 5% H2O2 as a reducing agent at 368 K with 1 M H2SO4 and 50 g/L pulp density, the leaching of cobalt (79.2%) and manganese (84.6%) were significantly improved in 240 min. With the addition of 0.075 M NaHSO3 as a reducing agent, ~96.7% Li, 91.6% Co, 96.4% Ni and 87.9% Mn were recovered under similar conditions. Sodium bisulfite addition results in better recovery of cobalt and manganese by reducing them to their lower oxidation states. The HSC evaluation of thermodynamic feasibility vis-à-vis x-ray diffraction and scanning electron microscopy characterization of residues generated by leaching with hydrogen peroxide and sodium bisulfite substantiates the governing mechanism.

  5. Leaching remediation of a heavy metal contaminated soil using tartaric acid%利用酒石酸土柱淋洗法修复重金属污染土壤

    Institute of Scientific and Technical Information of China (English)

    可欣; 张昀; 李培军; 李润东

    2009-01-01

    The remediation of a heavy metal(HM)contaminated soil was studied by using an environmentallyfriendly extractant of tartaric acid.Column leaching experiments were performed to analyze the effects of tartaric acid five-portion style leaching and ten-portion style leaching on heavy metals removal as well as the differences of heavy metals speeiation before and after tartaric acid treatment.Results show that 2.5 L tartaric acid five-portion style leaching was more effective than ten.poaion style leaching for removal of heavy metals from the contaminated soil,attaining 91.3%Cd,11.1%Pb.39.2%Zn and 11.1%Cu.The breakthrough curve of lead Was slower than other three heavy metals.Sequential fractionations of treated and untreated soil samples showed that tartaric acid was very effective in removing the exchangeable and carbonate fractions of heavy metals from the contaminated soils.The contents of heavy metals in Fe-Mn oxide fraction were also significantly decreased by tartaric acid leaching treatment.The heavy metals in organic matter fraction and residual fraction could not be removed by tartaric acid.This indicates that tartaric acid is a promising agent for remediation of HM contaminated soils.However,further research is required before the method can be used for in situ remediation of contaminatedsites.%通过室内模拟试验,采用土柱淋洗方法,研究酒石酸溶液两种不同添加方式对冶炼厂土壤中重金属离子去除率的影响,采用连续分级方法研究了淋洗前后冶炼厂土壤中重金属形态的变化.结果表明,2.5 L酒石酸5次加样的淋洗效果明显好于10次加样的淋洗效果,其中5次加样淋洗能去除91.3%的Cd,11.1%的Pb,39.2%的Zn,11.1%的Cu;淋洗过程中铅的穿透曲线明显滞后于镉、铜和锌3种重金属离子.形态分级结果表明,酒石酸5次加样淋洗能有效去除污染土壤中交换态和碳酸盐结合态部分重金属离子,明显降低氧化物结合态部分重金属离子,而

  6. Immobilized waste leaching

    International Nuclear Information System (INIS)

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

  7. Cross-current leaching of indium from end-of-life LCD panels

    Energy Technology Data Exchange (ETDEWEB)

    Rocchetti, Laura; Amato, Alessia; Fonti, Viviana [Department of Life and Environmental Sciences, Università Politecnica delle Marche, Via Brecce Bianche, 60131 Ancona (Italy); Ubaldini, Stefano [Institute of Environmental Geology and Geoengineering IGAG, National Research Council, Via Salaria km 29300, 00015 Montelibretti, Rome (Italy); De Michelis, Ida [Department of Industrial Engineering, Information and Economy, University of L’Aquila, Via Giovanni Gronchi 18, 67100, Zona industriale di Pile, L’Aquila (Italy); Kopacek, Bernd [ISL Kopacek KG, Beckmanngasse 51, 1140 Wien (Austria); Vegliò, Francesco [Department of Industrial Engineering, Information and Economy, University of L’Aquila, Via Giovanni Gronchi 18, 67100, Zona industriale di Pile, L’Aquila (Italy); Beolchini, Francesca, E-mail: f.beolchini@univpm.it [Department of Life and Environmental Sciences, Università Politecnica delle Marche, Via Brecce Bianche, 60131 Ancona (Italy)

    2015-08-15

    Graphical abstract: Display Omitted - Highlights: • End-of-life LCD panels represent a source of indium. • Several experimental conditions for indium leaching have been assessed. • Indium is completely extracted with 2 M sulfuric acid at 80 °C for 10 min. • Cross-current leaching improves indium extraction and operating costs are lowered. • Benefits to the environment come from reduction of CO{sub 2} emissions and reagents use. - Abstract: Indium is a critical element mainly produced as a by-product of zinc mining, and it is largely used in the production process of liquid crystal display (LCD) panels. End-of-life LCDs represent a possible source of indium in the field of urban mining. In the present paper, we apply, for the first time, cross-current leaching to mobilize indium from end-of-life LCD panels. We carried out a series of treatments to leach indium. The best leaching conditions for indium were 2 M sulfuric acid at 80 °C for 10 min, which allowed us to completely mobilize indium. Taking into account the low content of indium in end-of-life LCDs, of about 100 ppm, a single step of leaching is not cost-effective. We tested 6 steps of cross-current leaching: in the first step indium leaching was complete, whereas in the second step it was in the range of 85–90%, and with 6 steps it was about 50–55%. Indium concentration in the leachate was about 35 mg/L after the first step of leaching, almost 2-fold at the second step and about 3-fold at the fifth step. Then, we hypothesized to scale up the process of cross-current leaching up to 10 steps, followed by cementation with zinc to recover indium. In this simulation, the process of indium recovery was advantageous from an economic and environmental point of view. Indeed, cross-current leaching allowed to concentrate indium, save reagents, and reduce the emission of CO{sub 2} (with 10 steps we assessed that the emission of about 90 kg CO{sub 2}-Eq. could be avoided) thanks to the recovery of indium

  8. ALKALINE CARBONATE LEACHING PROCESS FOR URANIUM EXTRACTION

    Science.gov (United States)

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

    1957-11-12

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

  9. 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.

  10. A classification and regression tree model of controls on dissolved inorganic nitrogen leaching from European forests

    International Nuclear Information System (INIS)

    Often, there is a non-linear relationship between atmospheric dissolved inorganic nitrogen (DIN) input and DIN leaching that is poorly captured by existing models. We present the first application of the non-parametric classification and regression tree approach to evaluate the key environmental drivers controlling DIN leaching from European forests. DIN leaching was classified as low (15 kg N ha-1 year-1) at 215 sites across Europe. The analysis identified throughfall NO3- deposition, acid deposition, hydrology, soil type, the carbon content of the soil, and the legacy of historic N deposition as the dominant drivers of DIN leaching for these forests. Ninety four percent of sites were successfully classified into the appropriate leaching category. This approach shows promise for understanding complex ecosystem responses to a wide range of anthropogenic stressors as well as an improved method for identifying risk and targeting pollution mitigation strategies in forest ecosystems. - Classification and regression trees provide new insights into the non-linear behaviour of nitrogen leaching from forests

  11. Leach behavior of high-level borosilicate glasses under deep geological environment

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Seung Soo; Chun, Kwan Sik; Park, Hyun Soo

    1998-02-01

    This report presents an overview of the activities in high-level radioactive waste glass which is considered as the most practicable form of waste, and also is intended to be used in the disposal of national high-level radioactive waste in future. Leach theory of waste glass and the leach effects of ground water, metal barrier, buffer materials and rocks on the waste glass were reviewed. The leach of waste glass was affected by various factors such as composition, pH and Eh of ground water, temperature, pressure, radiation and humic acid. The crystallization, crack, weathering and the formation of altered phases of waste glass which is expected to occur in real disposal site were reviewed. The results of leaching in laboratory and in-situ were compared. The behaviors of radioactive elements leached from waste glass and the use of basalt glass for the long-term natural analogue of waste glass were also written in this report. The appraisal of durability of borosilicate waste glass as a waste media was performed from the known results of leach test and international in-situ tests were introduced. (author). 134 refs., 15 tabs., 24 figs

  12. Main means for reducing the production costs in process of leaching uranium

    International Nuclear Information System (INIS)

    The production costs in process of leaching uranium have been reduced by controlling mixture ratio of crudes, milling particle size, liquid/solid mass ratio of leaching pulp, potential and residue acidity, and improving power equipment

  13. 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.

  14. Leaching refuse after sphalerite mineral for extraction zinc and cobalt

    OpenAIRE

    S. Brožová; J. Drápala; Kursa, M.; Pustějovská, P.; S. Jursová

    2016-01-01

    The paper deals with a possibility of zinc and cobalt extraction from refuse after sphalerite mineral leaching. It contains theoretic analysis of hydrometallurgical processes. Practical part describes samples and their leaching in 10 % and 20 % sulphuric acid. In the end of the paper it is evaluated under which conditions the highest yield of zinc and cobalt from refuse after sulphide ore leaching is reached. Web of Science 55 3 499 497

  15. 钠盐焙烧-酸浸处理高铝高硅极难选褐铁矿研究%Research on Sodium Salt Roasting-Acid Leaching Technology for High-alumina and High-silicon Refractory Limonite

    Institute of Scientific and Technical Information of China (English)

    舒聪伟; 唐云; 王在谦; 张覃

    2012-01-01

    采用钠盐焙烧-酸浸工艺处理以部分铁氧化物呈浸染状分布在粘土矿物中的某高铝硅极难选褐铁矿.通过单因素试验分别考察了焙烧工艺中焙烧温度、焙烧时间、钠盐用量、磨矿粒度等对焙烧的影响,酸浸工艺中考察了硫酸浓度、液固比、酸浸温度和时间等因素对浸出指标的影响.试验结果表明,在磨矿粒度为-0.074 mm粒级占90.36%,碳酸钠用量为15%,焙烧温度为950℃,焙烧时间为30 min,硫酸浓度为7%,液固比为15:1,酸浸温度为60℃,酸浸时间15 min条件下,可获得TFe品位为60.21%,回收率为93.49%,SiO2和Al2O3含量分别为3.28%和6.81%的铁精矿.%The sodium salt roasting-acid leaching technology was adopted to treat high-alumina and high-silicon refractory limonite with part of iron oxides disseminated in the clay minerals. Some single-factor tests were conducted to investigate the effects of roasting temperature, roasting time, sodium salt consumption and grinding size, respectively, on the roasting, as well as the effects of sulfuric acid concentration, L/S ratio, acid leaching temperature and time on the leaching index. The test results showed that under the following conditions, such as the grinding size of -0. 074 mm 90.36% , the dosage of sodium carbonate of 15% , roasting for 30 mins at the temperature of 950℃ , sulfuric acid concentration of 7% , L/S ratio of 15: 1 , acid leaching for 15 mins at the temperature of 60 ℃ , the iron concentrates containing 3.28%SiO2 and 6.81%A12O3 were obtained with Tfe grade of 60.21% at a recovery of 93.49%.

  16. Removal of uranium and gross radioactivity from coal bottom ash by CaCl2 roasting followed by HNO3 leaching

    International Nuclear Information System (INIS)

    Highlight: • Roasting the ash with CaCl2 enhanced the removal of uranium and gross radioactivity. • 87.3% of the total uranium was removed via the optimized roast-leach process. • Nearly 90% of gross α and β radioactivity was removed via the roast-leach process. • Molten CaCl2 promoted the incorporation of Ca and Al into Si-O matrices in ash. • Radionuclides were removed by the acid decomposition of newly formed silicates. - Abstract: A roast-leach method using CaCl2 and HNO3 to remove uranium and gross radioactivity in coal bottom ash was investigated. Heat treatment of the ash with 100% CaCl2 (900 °C, 2 h) significantly enhanced uranium leachability (>95%) compared with direct acid-leaching (22.6–25.5%). The removal efficiency of uranium and gross radioactivity increased steeply with increasing CaCl2 content, from 10% to 50%, and a HNO3 leaching time from 5 min to 1 h, but remained nearly constant or decreased slightly with increasing CaCl2 dosage >50% or acid-leaching time >1 h. The majority of the uranium (87.3%), gross α (92.9%) and gross β (84.9%) were removed under the optimized roast-leach conditions (50% CaCl2, 1 M HNO3 leaching for 1 h). The mineralogical characteristics of roasted clinker indicated that molten CaCl2 promoted the incorporation of Ca into silica and silicates and resulted in its progressive susceptibility to acid attack. Uranium and other radionuclides, most likely present in the form of silicates or in association with miscellaneous silicates in the highest density fraction (>2.5 g mL−1), were probably leached out as the result of the acid decomposition of newly formed “gelatinizing silicates”

  17. Uranium leaching by fungal metabolite

    International Nuclear Information System (INIS)

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

  18. Stability Analysis and Stabilization of Miduk Heap Leaching Structure, Iran

    Directory of Open Access Journals (Sweden)

    Mehdi Amini

    2013-06-01

    Full Text Available To construct copper heap leaching structures, a stepped heap of ore is placed over an isolated sloping surface and then washed with sulphuric acid. The isolated bed of such a heap consists of some natural and geosynthetic layers. Shear strength parameters between these layers are low, so they form the possible sliding surfaces of the heaps. Economic and environmental considerations call for studying such slides. In this study, firstly, results of the laboratory tests carried on the materials of the heap leaching structures bed are presented. Then, the instability mechanisms of such structures are investigated and proper approaches are summarized for their stabilization. Finally, stability of the Miduk copper heap is evaluated as a case history, and appropriate approaches and their effects are discussed for its stabilization.

  19. 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

  20. The effectiveness of surface liming in ameliorating the phytotoxic effects of soil contaminated by copper acid leach pad solution in an arid ecosystem

    Science.gov (United States)

    Golos, Peter

    2016-04-01

    Revegetation of sites following soil contamination can be challenging especially in identifying the most effective method for ameliorating phytotoxic effects in arid ecosystems. This study at a copper mine in the Great Sandy Desert of Western Australia investigated vegetation restoration of a site contaminated by acid (H2SO4) leach pad solution. Elevated soil copper at low soil pH is phytotoxic to plant roots inhibiting root elongation. In arid ecosystems where rapid root growth is crucial for seedling survival post germination physical or chemical barriers to root growth need to be identified and ameliorated. Initial attempt at rehabilitation of contaminated site with hydrated lime (CaOH2) at 2 tonnes/ha followed by ripping to 30 cm depth then seeding was ineffective as successful seedling emergence was followed by over 90% seedling mortality which was 10-fold greater than seedling mortality in an uncontaminated reference site. High mortality was attributed to seedling roots being impededed as soil water was more than 3-fold greater at 5 to 40 cm depth in contaminated site than reference site. In response to high seedling mortality after emergence test pits were dug to 1 m deep to collect soil samples at 10 cm intervals for phytotoxicity testing and to measure soil pH-CaCl2, copper (DPTA ion extraction), electrical conductivity and gravimetric water content in three replicate pits at three replicate sites. Also, soil impedance was measured down the soil profile at 5 cm intervals at six replicate points/pit. For phytotoxicity testing soil samples were placed into three replicate plastic pots/sample and seeded with 10 seeds of Avena sativa and watered daily. Seedlings were harvested after at least two weeks after seedling emergence and rooting depth in pots measured. There was no difference in seedling emergence and survival of seedlings between contaminated and uncontaminated soil samples however mean seedling root growth was significantly lower in soil samples

  1. The effectiveness of surface liming in ameliorating the phytotoxic effects of soil contaminated by copper acid leach pad solution in an arid ecosystem

    Science.gov (United States)

    Golos, Peter

    2016-04-01

    Revegetation of sites following soil contamination can be challenging especially in identifying the most effective method for ameliorating phytotoxic effects in arid ecosystems. This study at a copper mine in the Great Sandy Desert of Western Australia investigated vegetation restoration of a site contaminated by acid (H2SO4) leach pad solution. Elevated soil copper at low soil pH is phytotoxic to plant roots inhibiting root elongation. In arid ecosystems where rapid root growth is crucial for seedling survival post germination physical or chemical barriers to root growth need to be identified and ameliorated. Initial attempt at rehabilitation of contaminated site with hydrated lime (CaOH2) at 2 tonnes/ha followed by ripping to 30 cm depth then seeding was ineffective as successful seedling emergence was followed by over 90% seedling mortality which was 10-fold greater than seedling mortality in an uncontaminated reference site. High mortality was attributed to seedling roots being impededed as soil water was more than 3-fold greater at 5 to 40 cm depth in contaminated site than reference site. In response to high seedling mortality after emergence test pits were dug to 1 m deep to collect soil samples at 10 cm intervals for phytotoxicity testing and to measure soil pH-CaCl2, copper (DPTA ion extraction), electrical conductivity and gravimetric water content in three replicate pits at three replicate sites. Also, soil impedance was measured down the soil profile at 5 cm intervals at six replicate points/pit. For phytotoxicity testing soil samples were placed into three replicate plastic pots/sample and seeded with 10 seeds of Avena sativa and watered daily. Seedlings were harvested after at least two weeks after seedling emergence and rooting depth in pots measured. There was no difference in seedling emergence and survival of seedlings between contaminated and uncontaminated soil samples however mean seedling root growth was significantly lower in soil samples

  2. Gold and palladium adsorption from leached electronic scrap using ordered mesoporous carbon nanoscaffolds

    Energy Technology Data Exchange (ETDEWEB)

    McDowell, Rocklan; Dutech, Guy

    2014-09-01

    Ordered mesoporous carbon (OMC) nanoscaffolds are engineered agglomerates of carbon nanotubes held together by small carbon nanofibers with uniform pore sizes, high pore volume, and high channel permeability. These materials exhibit very high affinity for the adsorption of gold from aqueous acidic mixtures. The efficiency of gold recovery is comparable to those typically accomplished using biopolymer-based adsorbents. The adsorption efficiency for other precious metals such as palladium and platinum is lower. Studies on the precious metal (Au, Pd) adsorption on OMC materials from actual liquors of leached electronics will be presented. Adsorption properties will be compared for several different sorbents used for the recovery of precious metals. The leach liquor compositions for three different types of electronic scrap materials (personal computer board, cell phone and tv input/output board) will be presented. The sorption efficiencies for Au, Pd, together with a spectrum of competing and non-competing metals, from such leach mixtures will be compared.

  3. Carbonate leaching of uranium and hydrogen peroxide stabilizer therefor

    International Nuclear Information System (INIS)

    In the carbonate leaching process for the solution mining of subterranean uranium containing formations in which an injection well is drilled and completed within the uranium formation; alkaline carbonate uranium leaching solution and sufficient hydrogen peroxide are injected through the injection wells into the formation whereby uranium values are produced from production wells, characterized by providing in the leaching solution a mixture of 1-hydroxyethylidene-1,1-diphosphonic acid and an alkali metal pyrophosphate in a weight ratio of from 1 to 10 to 10 to 1, the amount of said mixture being sufficient to inhibit decomposition of the hydrogen peroxide in said leaching solution

  4. Leaching from municipal solid waste incineration residues

    Energy Technology Data Exchange (ETDEWEB)

    Hyks, J.

    2008-02-15

    range of elements was adequately predicted over a liquid-to-solid ratio of 250 L kg-1 corresponding to more than 10,000 years in a typical landfill. Overall, only a minor fraction of many potential pollutants (e.g. heavy metals) present in MSWI residues have been shown leachable even during long-term percolation experiments; typically, less than 1% of initially present As, Cr, Sb, Cu, Cd, and Pb has leached. (ln)

  5. Study on process of recovering lead from acid leaching residue by precipitation transformation method%沉淀转化法综合回收酸浸渣中铅的工艺研究

    Institute of Scientific and Technical Information of China (English)

    张福元; 俎小凤; 彭国敏

    2013-01-01

    Comprehensive recovery of low-grade lead in the acid leaching residue from cyanidation process for golden leaching was made through precipitation transformation method.The recovery process was introduced.Influences of factors, such as mass ratio of liquid to solid (L/S), amount of ammonium bicarbonate, and reaction time on converting rate of lead in the reaction process of ammonium bicarbonate and acid leaching residue were also studied through orthogonal tests.The optimum conditions were as follows:mass ratio of L/S was 2.0,amount of ammonium bicarbonate was 30 g,and reaction time was 2.0 h. The transformation ratio of lead reached 97% under those conditions.%通过沉淀转化法对氰化提金工艺酸浸渣中低品位铅进行了综合回收.介绍了回收工艺流程,通过正交实验考察了酸浸渣采用碳酸氢铵转化过程中液固比、碳酸氢铵用量、转化时间等因素对铅转化率的影响,确定了转化反应的最佳条件为:转化液固质量比为2.0、碳酸氢铵用量为30 g、转化时间为2.0 h.在最佳条件下反应,铅转化率可达97%.

  6. 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.

  7. YACON INULIN LEACHING DURING HOT WATER BLANCHING

    OpenAIRE

    Caroline Fenner Scher; Adriano Brandelli; Caciano Zapata Noreña

    2015-01-01

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

  8. Leaching of polycyclic aromatic hydrocarbons from power plant lignite ash--influence of parameters important for environmental pollution.

    Science.gov (United States)

    Pergal, Miodrag M; Relić, Dubravka; Tešić, Zivoslav Lj; Popović, Aleksandar R

    2014-03-01

    Nikola Tesla B power plant (TENT B), located at the Sava River, in Obrenovac, 50 km west from the Serbian's capital, Belgrade, is the second largest coal-fired power plant in the country, consisting of two blocks, each of 620 MW capacity. In order to investigate the threat polycyclic aromatic hydrocarbons (PAHs) from deposited coal ash, obtained by coal combustion in this power plant, can represent for the surrounding environment, samples of coal ash were submitted to extraction with river water used for transport of coal ash to the dump, as well as with water of different ionic strength and acidity. It was found that, out of 16 EPA priority PAHs, only naphthalene, acenaphthylene, fluorene, phenantrene, fluoranthene, and pyrene were found in measurable concentrations in the different extracts. Their combined concentration was around 0.1 μg/L, so they do not, in terms of leached concentrations, represent serious danger for the surrounding environment. In all cases of established (and leached) PAH compounds, changes of ionic strength, acidity, or the presence of organic compounds in river water may to some extent influence the leached concentrations. However, under the examined conditions, similar to those present in the environment, leached concentrations were not more than 50 % greater than the concentrations leached by distilled water. Therefore, water desorption is likely the most important mechanism responsible for leaching of PAH compounds from filter coal ash. PMID:24243163

  9. Leaching of polycyclic aromatic hydrocarbons from power plant lignite ash--influence of parameters important for environmental pollution.

    Science.gov (United States)

    Pergal, Miodrag M; Relić, Dubravka; Tešić, Zivoslav Lj; Popović, Aleksandar R

    2014-03-01

    Nikola Tesla B power plant (TENT B), located at the Sava River, in Obrenovac, 50 km west from the Serbian's capital, Belgrade, is the second largest coal-fired power plant in the country, consisting of two blocks, each of 620 MW capacity. In order to investigate the threat polycyclic aromatic hydrocarbons (PAHs) from deposited coal ash, obtained by coal combustion in this power plant, can represent for the surrounding environment, samples of coal ash were submitted to extraction with river water used for transport of coal ash to the dump, as well as with water of different ionic strength and acidity. It was found that, out of 16 EPA priority PAHs, only naphthalene, acenaphthylene, fluorene, phenantrene, fluoranthene, and pyrene were found in measurable concentrations in the different extracts. Their combined concentration was around 0.1 μg/L, so they do not, in terms of leached concentrations, represent serious danger for the surrounding environment. In all cases of established (and leached) PAH compounds, changes of ionic strength, acidity, or the presence of organic compounds in river water may to some extent influence the leached concentrations. However, under the examined conditions, similar to those present in the environment, leached concentrations were not more than 50 % greater than the concentrations leached by distilled water. Therefore, water desorption is likely the most important mechanism responsible for leaching of PAH compounds from filter coal ash.

  10. Vitamin B12 and folic acid deficiency presenting as acute febrile illness: a case report

    Directory of Open Access Journals (Sweden)

    Khwaja Saifullah Zafar

    2014-08-01

    Full Text Available Megaloblastic anemia is not uncommon in India, but data is insufficient regarding its presentation as pyrexia. We report the case of a patient who presented with pyrexia and anaemia, which after exclusion of infective, inflammatory or endocrine causes was attributed to megaloblastic anaemia secondary to vitamin B12 and folic acid deficiency. The patient's fever responded to treatment of vitamin B12 and folic acid deficiency. [Int J Res Med Sci 2014; 2(4.000: 1768-1770

  11. Leaching studies for tin recovery from waste e-scrap.

    Science.gov (United States)

    Jha, Manis Kumar; Choubey, Pankaj Kumar; Jha, Amrita Kumari; Kumari, Archana; Lee, Jae-Chun; Kumar, Vinay; Jeong, Jinki

    2012-10-01

    Printed circuit boards (PCBs) are the most essential components of all electrical and electronic equipments, which contain noteworthy quantity of metals, some of which are toxic to life and all of which are valuable resources. Therefore, recycling of PCBs is necessary for the safe disposal/utilization of these metals. Present paper is a part of developing Indo-Korean recycling technique consists of organic swelling pre-treatment technique for the liberation of thin layer of metallic sheet and the treatment of epoxy resin to remove/recover toxic soldering material. To optimize the parameters required for recovery of tin from waste PCBs, initially the bench scale studies were carried out using fresh solder (containing 52.6% Sn and 47.3% Pb) varying the acid concentration, temperature, mixing time and pulp density. The experimental data indicate that 95.79% of tin was leached out from solder material using 5.5M HCl at fixed pulp density 50 g/L and temperature 90°C in mixing time 165 min. Kinetic studies followed the chemical reaction controlled dense constant size cylindrical particles with activation energy of 117.68 kJ/mol. However, 97.79% of tin was found to be leached out from solder materials of liberated swelled epoxy resin using 4.5M HCl at 90°C, mixing time 60 min and pulp density 50 g/L. From the leach liquor of solder materials of epoxy resin, the precipitate of sodium stannate as value added product was obtained at pH 1.9. The Pb from the leach residue was removed by using 0.1M nitric acid at 90°C in mixing time 45 min and pulp density 10g/L. The metal free epoxy resin could be disposed-of safely/used as filling material without affecting the environment.

  12. 从某铀矿石硫酸浸出液中回收铀、铜试验研究%Experiment Research on Recovery of Uranium and Copper From Leaching Solution of Uranium Ore With Sulfuric Acid

    Institute of Scientific and Technical Information of China (English)

    刘辉; 周根茂; 孟运生; 郑英; 师留印; 程浩

    2013-01-01

      某铀矿石硫酸浸出液中含有铀和铜,研究了从中综合回收铀和铜。试验结果表明:采用201×7树脂吸附铀,用酸性氯化钠溶液淋洗负载树脂,然后用氢氧化钠溶液从淋洗液中沉淀铀,铀回收率为98.4%;对铀的吸附尾液,采用循环铁粉置换法回收铜,铜回收率为90%。采用该方法可实现铀、铜的综合回收。%Recovery of uranium and copper from sulfuric acid leaching solution of a uranium ore has been studied .The results showed that uranium recovery was 98 .4% by adsorption uranium using 201 × 7 resin from the leaching solution ,and desorption uranium using acidic sodium chloride solution from loaded resin ,then precipitating uranium from the stripping liquid .The copper in the adsorption tail liquid was be replaced using iron powder ,recovery of copper was 90% .Comprehensive recovery of uranium and copper can be realized by the method .

  13. 造球焙烧-低酸浸出五氧化二钒试验研究%Experimental Research on Leaching V2O5 hv Palletizing Roasting and Low Acid

    Institute of Scientific and Technical Information of China (English)

    陈庆根; 黄怀国; 叶志勇; 熊明

    2011-01-01

    The experimental research on leaching V2O5 by palletizing roasting and low acid was carried on a stone coach vanadium ore. The results show when the vanadium ore is pretreated under the condition of the grinding fineness of l5% passing 200 mesh,the concentration of sulfuric acid is 4% ,the ration of liquid to solid is 2,the leaching rate of V2Oj can reach 88.15% under the normal atmospheric temperature.%对某石煤钒矿采用造球焙烧-低酸浸出五氧化二钒试验研究,结果表明:该钒矿在粒度- 200目75%造球焙烧预处理,焙砂在硫酸浓度4%、浸出时间1h、矿浆液固比2、常温浸出的条件下,五氧化二钒浸出率可达88.15%.

  14. Ni, Co recovery study and Fe by acid leaching in columns; Estudio de la extraccion de Ni, Co y Fe en lateritas por medio de lixiviacion acida en columnas

    Energy Technology Data Exchange (ETDEWEB)

    Yorio, C. di; Betancourt, E.; Vivas, R.; Rus, J.

    2006-07-01

    In the following work the possibility of the mic kel recovery by hydrometallurgy extraction for nickeliferous laterite is studied. The work looks for to study the technical viability of the extraction of nickel and cobalt by means of the application of heap leaching. The ore is chemically and physically characterized with the purpose of analyzes its composition and mineral phase, by means of x-rays diffraction, quantitative chemical analysis and elementary chemical analysis by electronic microscopy. One the ore is characterized, it is mixed with sulfuric acid to relations 0.05; 0.1 and 0.2 g acid/g to agglomerated pellets and paste, with the aim to improve the percolation in column, due to the argillaceous nature of the ore leaching rate ranged from 0.305 to 1.06 x 10 l/h m''2 and in the agglomerate condition of the percolation l/h m''2 improves at interval 3.05 to 6.11 x 100 l/h m''2. (Author)

  15. Study of uranium leaching from industrial residues of Industrias Nucleares do Brazil S.A. (INB), Caetite, Bahia, Brazil

    Energy Technology Data Exchange (ETDEWEB)

    Formiga, Thiago S.; Morais, Carlos A., E-mail: cmorais@cdtn.b [Centro de Desenvolvimento da Tecnologia Nuclear (CDTN/CNEN-MG), Belo Horizonte, MG (Brazil); Gomiero, Luiz A., E-mail: gomiero@inb.gov.b [Industrias Nucleares do Brasil S/A (INB), Caetite, BA (Brazil)

    2011-07-01

    The uraniferous district of Lagoa Real, located in the south-central region of the state of Bahia, has reserves estimated at 100,000 tons of uranium, which is enough to supply Angra I, II and III for 100 more years. The process adopted for the beneficiation of the uranium ore from Lagoa Real is heap leaching, a static process in which the ore is crushed, disposed in heaps and irrigated with a sulfuric acid solution to remove the uranium. This technique has a relatively low cost of implementation, although the yield of uranium recovery is low, with an uranium content in the leached residue of 700 {mu}g/g U{sub 3}O{sub 8} for ores with an initial content of 2,700 {mu}g/g U{sub 3}O{sub 8}. With the deepening of the mine pit, an increase in the carbonate content in the ore was noted, which required a higher acid consumption in the leaching. In order to reduce the concentration of carbonates, a study of the ore concentration by flotation column was accomplished. The flotation reject had high carbonate content, with a uranium content of about 2,300 {mu}g/g U{sub 3}O{sub 8} for flotation in one column and 1,100 {mu}g/g U{sub 3}O{sub 8} for flotation in two columns. This paper presents the study of the leaching process for the recovery of the uranium present in the residue of the heap leaching and in the carbonated residue from the flotation of the anomaly 13 ore. The results indicate the feasibility of treating the waste of the heap leaching through dynamic leaching. The study of the uranium leaching from the flotation residue through acid leaching technique indicated a recovery of 96% of uranium, however with a high consumption of acid, around 450 kg/t, showing that for this case, the most suitable technique for the process is alkaline leaching. (author)

  16. Presentation

    Directory of Open Access Journals (Sweden)

    Paulo Henrique Freire Vieira

    2013-12-01

    Full Text Available This dossier focuses on one of the essential debate topics today about the territorial dimension of the new development strategies concerned with the worsening of the global socioecological crisis, that is: the challenges related to the activation and integration in networks of localized agri-food systems. For its composition, some contributions presented and debated during the VI International Conference on Localized Agri-food System - The LAFS facing the opportunities and challenges of the new global context have been gathered. The event took place in the city of Florianópolis, from May 21th to 25th of 2013. The event was promoted by the Federal University of Santa Catarina (UFSC and by the Center for the International Cooperation on Agricultural Research for Development (CIRAD. Besides UFSC and CIRAD, EPAGRI, State University of Santa Catarina (UDESC, as well as research institutes and universities from other states (UFMG, IEA/SP, UFS, UFRGS and Mexican and Argentinian partners from the RED SIAL Latino Americana also participated in the organization of lectures, discussion tables and workshops.

  17. 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.

  18. Presentation

    Directory of Open Access Journals (Sweden)

    Isidor Marí Mayans

    2004-04-01

    Full Text Available As was the case at the conference, "Humanities professions in the knowledge society", the Director of Humanities and Philology Studies at the UOC, Isidor Marí, presents this Dossier, and the subsequent virtual debate, with the aim of gaining useful conclusions, with specific repercussions on the organisation of the degree studies and its professional projection, especially at this time, which requires study plans to be redesigned in line with the Bologna process. In the author's opinion, we can only make the right operative decisions when we are able to understand the transformations taking place in the humanistic culture framed by the knowledge society, and to do so, debate has to be opened in which students, graduates, academics, researchers, professionals and analysts can all take part.In this article, Isidor Marí analyses the tensions and contradictions that arise when attempts are made to relate the concepts of the professional world, Humanities and the knowledge society. Firstly, neither are Humanities a profession nor the study of Humanities seen by students or society to be adaptable to the definition of professional profiles. However, this highlights an important paradox, as the culture economy, (and, thus, occupations in the cultural sector, is growing increasingly throughout western societies. Likewise, in terms of the relationship between Humanities and the knowledge society, the author describes and analyses how there currently coexist voices foreseeing the worst alongside those that see information and communications technologies opening the way for an enormously positive transformation in human civilisation and a new cultural era.

  19. Presentation

    Directory of Open Access Journals (Sweden)

    Eduardo Vicente

    2013-06-01

    Full Text Available In the present edition of Significação – Scientific Journal for Audiovisual Culture and in the others to follow something new is brought: the presence of thematic dossiers which are to be organized by invited scholars. The appointed subject for the very first one of them was Radio and the invited scholar, Eduardo Vicente, professor at the Graduate Course in Audiovisual and at the Postgraduate Program in Audiovisual Media and Processes of the School of Communication and Arts of the University of São Paulo (ECA-USP. Entitled Radio Beyond Borders the dossier gathers six articles and the intention of reuniting works on the perspectives of usage of such media as much as on the new possibilities of aesthetical experimenting being build up for it, especially considering the new digital technologies and technological convergences. It also intends to present works with original theoretical approach and original reflections able to reset the way we look at what is today already a centennial media. Having broadened the meaning of “beyond borders”, four foreign authors were invited to join the dossier. This is the first time they are being published in this country and so, in all cases, the articles where either written or translated into Portuguese.The dossier begins with “Radio is dead…Long live to the sound”, which is the transcription of a thought provoking lecture given by Armand Balsebre (Autonomous University of Barcelona – one of the most influential authors in the world on the Radio study field. It addresses the challenges such media is to face so that it can become “a new sound media, in the context of a new soundscape or sound-sphere, for the new listeners”. Andrew Dubber (Birmingham City University regarding the challenges posed by a Digital Era argues for a theoretical approach in radio studies which can consider a Media Ecology. The author understands the form and discourse of radio as a negotiation of affordances and

  20. Simultaneous determination of butyltin and phenyltin species in sediments using ultrasound-assisted leaching

    Energy Technology Data Exchange (ETDEWEB)

    Carpinteiro, J.; Rodriguez, I.; Cela, R. [Dpto. Quimica Analitica, Nutricion y Bromatologia, Universidad de Santiago de Compostela (Spain)

    2001-08-01

    A fast and simple procedure is presented for the simultaneous leaching of butyl (mono, di and tributyl) and phenyl organotin species from sediment samples. Leached compounds are further ethylated with sodium tetraethylborate in aqueous medium, and analyzed by gas chromatography. After testing the stability of triphenyltin under different extraction conditions, ultrasound-assisted leaching at room temperature in the presence of acetic acid was been proposed as an extraction procedure compatible with the simultaneous determination of phenyl- and butyltin compounds in sediments. Recoveries between 70 and 90% were obtained for phenyl species in spiked samples prepared in the laboratory. Results for butyltin species were validated by use of the reference material PACS-2. Quantification limits, using GC-MIP-AES as measurement technique, were approximately 5-10 ng g{sup -1}. Precision in the consecutive analysis of three sediment samples varied between 3 and 10%. (orig.)

  1. Presentation

    Directory of Open Access Journals (Sweden)

    Nicanor Lopes

    2010-11-01

    Full Text Available The Journal Caminhando debuts with a new editorial format: eachmagazine will have a Dossier.In 2010 Christianity celebrated the centenary of Edinburgh. TheWorld Missionary Conference in Edinburgh in 1910 is regarded by manyas missiological watershed in the missionary and ecumenical movement.So the Faculty of Theology of the Methodist Church (FATEO decidedto organize a Wesleyan Week discussing the issue of mission. For anevent of this magnitude FATEO invited the Rev. Dr. Wesley Ariarajah,Methodist pastor and teacher of Sri Lanka with extensive experience inpastoral ministry in local churches and professor of History of Religionsand the New Testament at the Theological College of Lanka, maintainedby the Protestant Churches in Sri Lanka. In 1981 he was invited to jointhe World Council of Churches, where he presided for over ten years theCouncil of Interreligious Dialogue. From 1992 he served as Deputy GeneralSecretary of the WCC.The following texts are not the speeches of the Rev. Dr. WesleyAriarajah, for they will be published separately. Nevertheless, the journaldialogs with the celebrations of the centenary of Edinburgh, parting formthe intriguing theme: "Mission in the 21st century in Brazil". After all, howis it that mission takes place among us in personal, church, and communityactivities?Within the Dossier, as common to the journal, the textos are organizedas follows: Bible, Theology / History and Pastoral Care. Other items thatdo not fit within the Dossier, but, do articulate mission, can be found inthe section Declarations and Documents and Book Reviews.The authors of the Dossier have important considerations in buildinga contemporary missiological concept considering Brazilian reality.Anderson de Oliveira, in the Bible-Section, presents a significantexegeses of Matthew 26.6-13. What does it mean when Jesus is quotedwith the words: "For the poor always ye have with you, but me ye havenot always." Is this declaration challenging the gospels

  2. 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.

  3. 电解剥离-生物质酸浸回收废旧锂电池%Electrolytic stripping-biomass acid leaching-recycling spent Li-ion battery

    Institute of Scientific and Technical Information of China (English)

    徐筱群; 满瑞林; 张建; 刘琦; 徐娟; 孙祖眉

    2014-01-01

    采用电解剥离−浸出正极材料、P204萃取除铝、秸秆硫酸浸出电池渣、草酸沉钴等工艺回收废旧锂电池中的钴。结果表明:经过20~30 min的电解剥离,实现了电池粉与铝箔的分离,钴的浸出率为50%,电流效率为70%;通过两次P204错流萃取除铝后,萃余液中Al3+Co 2+含量可以降到0.4 mg/L,而钴却未损失;燕麦秸秆粉−硫酸浸出电池渣中钴的最佳工艺条件如下:硫酸2 mol/L、1 g电池渣加入0.5~0.7 g麦秆粉,固液比1:10,在80~90℃反应1~2 h,钴的浸出率达到98%以上;经三级浸出,COD的含量可降至1.3 g/L左右;草酸沉钴调节溶液温度为50℃, pH为2,保持n()/n(2−24CO)=1,1 h后钴的一次沉淀率达到92%以上,滤液pH为0.2,其滤液可作为电解浸出液循环使用。%Cobalt was recycled from spent Li-ion battery through the electrolytic stripping-leaching cathode material, P204 extraction Al, straw sulphuric acid leaching battery slag and oxalate precipitating cobalt. The results show that the battery powder can be separated from aluminum foil after 20−30 min electrolytic stripping process, the cobalt leaching rate is 50% and current efficiency is 70%. After two−stage P204 cross-flow extraction, Al3+Co 2+ remained in the raffinate can be dropped to 0.4 mg/L, and cobalt is not lose. Under the condition of sulfuric acid concentration 2 mol/L, adding 0.5−0.7 g straw powder into 1g battery slag, and liquid-solid ratio 1:10, the cobalt leaching rate is over 98% after 1−2 h in 80−90℃. After three−stage leaching process, COD content can drop to about 1.3 g/L. In oxalate precipitating process, adjusting the pH of solution to 2, keepingn( )/n(2−24CO) of 1, cobalt precipitation rate is above 92% after 1h reaction under 50℃, and pH of the filtrate is 0.2, which can be circulated used as electrolytic leaching liquid.

  4. Acidic ribosomal proteins and histone H3 from Leishmania present a high rate of divergence

    Directory of Open Access Journals (Sweden)

    Ysabel Montoya

    2000-08-01

    Full Text Available Another additional peculiarity in Leishmania will be discussed about of the amino acid divergence rate of three structural proteins: acidic ribosomal P1 and P2b proteins, and histone H3 by using multiple sequence alignment and dendrograms. These structural proteins present a high rate of divergence regarding to their homologous protein in Trypanosoma cruzi. At this regard, L. (V. peruviana P1 and T. cruzi P1 showed 57.4% of divergence rate. Likewise, L. (V. braziliensis histone H3 and acidic ribosomal P2 protein exhibited 31.8% and 41.7% respectively of rate of divergence in comparison with their homologous in T. cruzi.

  5. Solidified structure and leaching properties of metallurgical wastewater treatment sludge after solidification/stabilization process.

    Science.gov (United States)

    Radovanović, Dragana Đ; Kamberović, Željko J; Korać, Marija S; Rogan, Jelena R

    2016-01-01

    The presented study investigates solidification/stabilization process of hazardous heavy metals/arsenic sludge, generated after the treatment of the wastewater from a primary copper smelter. Fly ash and fly ash with addition of hydrated lime and Portland composite cement were studied as potential binders. The effectiveness of the process was evaluated by unconfined compressive strength (UCS) testing, leaching tests (EN 12457-4 and TCLP) and acid neutralization capacity (ANC) test. It was found that introduction of cement into the systems increased the UCS, led to reduced leaching of Cu, Ni and Zn, but had a negative effect on the ANC. Gradual addition of lime resulted in decreased UCS, significant reduction of metals leaching and high ANC, due to the excess of lime that remained unreacted in pozzolanic reaction. Stabilization of more than 99% of heavy metals and 90% of arsenic has been achieved. All the samples had UCS above required value for safe disposal. In addition to standard leaching tests, solidificates were exposed to atmospheric conditions during one year in order to determine the actual leaching level of metals in real environment. It can be concluded that the EN 12457-4 test is more similar to the real environmental conditions, while the TCLP test highly exaggerates the leaching of metals. The paper also presents results of differential acid neutralization (d-AN) analysis compared with mineralogical study done by scanning electron microscopy and X-ray diffraction analysis. The d-AN coupled with Eh-pH (Pourbaix) diagrams were proven to be a new effective method for analysis of amorphous solidified structure. PMID:26457922

  6. 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.

  7. Leaching of valuable elements from thermal power plant bottom ash using a thermo-hydrometallurgical process.

    Science.gov (United States)

    Bojinova, Darinka; Teodosieva, Ralitsa

    2016-06-01

    The solid industrial wastes generated from thermal power plants (TPPs) can be considered as renewable secondary sources for recovery of valuable metals. This study presents the results from investigations that integrated a thermo-hydro-metallurgical method for treatment of bottom ash obtained from the Enel Maritsa East 3 TPP in Bulgaria. Leaching was performed with 20, 30 and 40 wt% sulphuric acid, respectively, in an autoclave at 100(o)C, 120(o)C and 140(o)C for 120, 240, 360 and 480 min, at a constant value of the liquid/solid ratio. After autoclaving, the samples (suspensions) were diluted with a constant value of water and stirring at 50(o)C for 60 min. On the basis of the experimental data the leaching efficiency (α) of the elements in the liquid phase after filtration was estimated. The leaching of aluminium increases significantly with increasing of the temperature, reaching the maximum value of 70 wt%. The highest leaching efficiency values for the other elements are as follows: Fe (86.4%), Ca (86.6%), Na (86.6%), Ni (83.3%) and Zn (83.3%). The maximum value of leaching for Mg, K, Mn, Cu and Cr is in the interval of 46-70%. PMID:26951342

  8. Materials Characterization Center workshop on the leaching mechanisms of nuclear waste forms, December 7-8, 1982, Thousand Oaks, CA. Summary report

    International Nuclear Information System (INIS)

    Each of the six laboratories involved in the 3-yr leaching mechanism program presented a progress report on borosilicate glass studies. Presentations were made on various techniques for characterizing leached surfaces and on in situ characterization of leaching surfaces

  9. 复杂铜铅锌银混合精矿两段逆流氧压浸出工艺%Two stage adverse current oxygen pressure acid leaching of complex Cu-Pb-Zn-Ag bulk concentrate

    Institute of Scientific and Technical Information of China (English)

    徐斌; 钟宏; 王魁珽; 姜涛

    2011-01-01

    By mineralogical analysis, the primary lead and zinc minerals in the complex Cu-Pb-Zn-Ag bulk concentrate are separately galena and sphalerite. While the primary copper mineral of the concentrate and most of silver indwell in the tetrahedrite is difficult to be leached. The treatment of the complex Cu-Pb-Zn-Ag bulk concentrate by a two-stage adverse current oxygen pressure acid leaching was studied. The optimum process operating parameters of the initial sulfuric acid concentration 150 g/L, the first stage that liquid-to-solid ratio of 3, temperature of 135 ℃, oxygen partial pressure of 0.75 MPa and time of 2.0 h, and the initial sulfuric acid concentration of 80 g/L, the optimum parameters of the second stage that liquid-to-solid ratio of 3, temperature of 180 ℃, oxygen partial pressure of 1.0 MPa and time of 2.5 h were both established by conditional experiments. The enlarged verification experiment was carried out under the optimum conditioas, and the average leaching efficiencies of copper and zinc are separately as high as 93.23% and 99.47% in the experiment while the average leaching efficiencies of Fe and As as impurities are only 15.77% and 6.9%,respectively. The lead and silver stayed in residue in the main forms of sulfate and sulfide separately after the leaching, so the lead and silver are separated with copper and zinc completely.%通过对呷村铜铅锌银多金属混合精矿的矿物分析可知,铅、锌主要赋存于方铅矿、闪锌矿中,而大部分铜、银均为难浸出的黝铜矿所载.采用两段逆流氧压浸出工艺进行处理该矿,条件试验研究得出一、二段最佳浸出条件分别为硫酸浓度150 g/L、液固比3:1、反应温度135℃、氧分压O.75 MPa、浸出时间2.0 h;硫酸浓度80 g/L、液固比3:1、反应温度180℃、氧分压1.0 MPa、浸出时间2.5 h.9轮扩大验证循环浸出试验运行顺利,Cu和Zn的平均两段总浸出率分别为93.23%和99.47%,而

  10. Ferric Sulfate Leaching of Pyrrhotite Tailings between 30 to 55 °C

    OpenAIRE

    Nazanin Samadifard; Cheryl E. Devine; Elizabeth Edwards; Krishna Mahadevan; Vladimiros G. Papangelakis

    2015-01-01

    Mine tailings present major environmental issues in the mining industry. However due to the depletion of high-grade sulfide ores for metal recovery, tailings could also be a potential resource for certain valuable metals. The present study investigates the potential to recover nickel from pyrrhotite tailings. Leaching tests were performed in acidic ferric sulfate media with 0.14 wt % solids to keep the ferric concentration essentially constant. The temperature was varied between 30 and 55 °C,...

  11. Organic ligands influence leaching kinetics of fixated FGD material

    Energy Technology Data Exchange (ETDEWEB)

    Chin-Min Cheng; Yu Sik Hwang; John J. Lenhart; Harold W. Walker [Ohio State University, Columbus, OH (United States). Department of Civil and Environmental Engineering and Geodetic Science

    2008-10-15

    The presence of organic ligands, including oxalate, citrate, maleate and Pahokee peat humic acid (PPHA), influenced the leaching kinetics of fixated flue gas desulfurization (FGD) material in acidic solution (pH 2.9-5.0). In the presence of oxalate, the leaching was inhibited at all pH values examined. XRD and SEM analyses demonstrated that formation of a calcium oxalate mineral phase on the fixated FGD material surface created a surface layer which reduced the extent of leaching. Maleate and PPHA inhibited leaching at pH 2.9, but either promoted, inhibited, or had no effect on leaching, depending on the particular element, at pH 5.0. ATR-FTIR analysis indicated maleate and PPHA formed both inner- and outer-spherically bound species at pH 2.9, whereas at pH 5.0 only outer-sphere complexes seemed evident. These surface species likely inhibited the leaching process at pH 2.9 through a surface blocking mechanism. At pH 5.0, the ligand surface complexes either promoted or inhibited leaching, depending on the element, through a combination of direct and indirect mechanisms. Citrate significantly promoted the leaching process at all pH values examined. 43 refs., 6 figs., 3 tabs.

  12. 氟化钙参与石煤提钒过程的浸出行为研究%Acid-Leaching of Vanadium from Stone Coal with Calcium Fluoride Addition

    Institute of Scientific and Technical Information of China (English)

    王非; 张一敏; 黄晶; 刘涛; 赵杰; 张国斌

    2013-01-01

    The behavior of leaching vanadium from stone coal with calcium fluoride was researched under the conditions of 95 ℃,4 h,1 ml·g-1,15% (volume fraction) H2SO4 and 5% (mass fraction) calcium fluoride.The leaching rate of vanadium could reach 92.39%.Through the analyses of inductively coupled plasma atomic emission spectroscopy (ICP-AES),valence state vanadium and X-ray diffractometry (XRD) for the raw ore of stone coal,ICP-AES,X-ray photoelectron spectroscopy (XPS) and 19F liquid nuclear magnetic resonance (NMR) for the leachate,and XRD and scanning electron microscope (SEM) for the leaching residue,the whole leaching process could be summarized that calcium fluoride reacted with sulfuric acid to generate hydrofluoric acid and the hydrofluoric acid solution (HF) could enhance the leaching process owing to its strong destructiveness to vanadium-bearing minerals; calcite consumed part of acid to generate CaSO4 and CO2 ; chlorite and vanadium-bearing phlogopite were thoroughly broken down and released V,Al,K,Mg,Si etc.[AlF5] 2-and [SiF6] 2-were generated and left in the leachate after F-reacted with other elements in the vanadium leaching.In the process of intense stir,the released Ⅴ(Ⅲ) was oxidized into VO2+ by O2 from air to exist in leachate.Part of the released Al existed in leachate as Al3 + and others combined with F to generate [AlF5] 2-.Part of the released Si existed in residue as SiO2,and the rest combined with F to generate [SiF6] 2-.It was because the bond energies of Al-F and Si-F were bigger than that of Al-O and Si-O,and the generation of [AlF5] 2-and [SiF6] 2-made the leaching system more stable and facilitated leaching vanadium.%研究了氟化钙参与石煤提钒过程的浸出行为,浸出条件为95℃,4h,1ml·g-1,15%(体积分数)硫酸和5%(质量分数)氟化钙.在此条件下钒的浸出率可达到92.39%.通过对石煤原矿进行电感耦合等离子体原子发射光谱分析(ICP-AES)、钒价态分析和X射线衍射(XRD

  13. 宜昌某鳞片石墨浮选精矿酸浸脱杂试验%Deimpurity Experiments by Acid Leaching on a Flake Graphite Flotation Concentrate in Yichang

    Institute of Scientific and Technical Information of China (English)

    胡宇; 彭伟军; 王承二; 宋少先

    2015-01-01

    The carbon content of a flaky graphite flotation concentrate in Yichang was 93. 72%,-200 mesh accounted for 83. 27%. Main impurity compositions were quartz,kaolin and illite. Mixed acid leaching process condition research was per-formed in order to obtain high purity graphite. The results indicated that the molar ratio of HCl to HF was 1 ∶ 4,the volume to mass ratio of mixed acid to graphite was 3 ∶ 1 and leaching at 60 ℃ for 6 h,the removal effect of impurities was the best and high purity graphite with fixed carbon content of 99. 1% could be obtained. The analysis results of XRD and SEM indicated that acid leaching process could efficiently dissolve the impurities without destroy the component and structure of graphite,thus can be an important method to obtain high purity graphite.%宜昌某鳞片石墨浮选精矿碳含量达93.72%,-200目占83.27%,主要杂质成分为石英、高岭石和伊利石。为了获得高纯石墨精矿,采用混合酸对试样进行了酸浸工艺条件研究。结果表明,混合酸和石墨的体积质量比为3∶1,HF与HCl的物质的量之比为1∶4,酸浸温度为40℃,酸浸时间为6 h情况下,可获得固定碳含量为99.1%的高纯石墨精矿。石墨精矿的XRD和SEM分析表明,酸浸工艺可高效地溶出试样中的杂质,且不破坏石墨成分和结构,是获取高品质石墨的重要手段。

  14. 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.

  15. 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.

  16. 热酸浸出-低污染沉矾工艺的生产实践%Production Practice of Low Pollution Jarosite Process in Hot Acid Leaching

    Institute of Scientific and Technical Information of China (English)

    朱永良

    2014-01-01

    介绍了热酸浸出-低污染沉矾的工艺原理和该工艺在某企业的生产实践,针对原料含铁高造成沉矾工序操作不稳定,在预中和时出现黄铁矾早熟,造成除铁效率降低,渣含锌等问题进行讨论。%This paper introduces zinc hydrometallurgy process of low pollution jarosite process in hot acid Leaching and production practice in Chifeng non -ferrous of China zinc industry limited company . In this thesis , it is mainly discussed the unsteady operation of jarosite process and the Zinc Content in the Lead -Silver Slag.

  17. Enrichment and Recovery of Pt from Spent Petroleum Reforming Catalyst by Ammonium Salt Roasting-acid Leaching Process%铵盐焙烧-酸浸法从石油重整废催化剂中富集回收铂的研究

    Institute of Scientific and Technical Information of China (English)

    董海刚; 赵家春; 杨海琼; 李博捷; 崔浩

    2014-01-01

    Enrichment and recovery of Pt from spent petroleum reforming catalyst by ammonium salt roasting-acid leaching process were studied. The result showed that, when the roasting suitable conditions as follows: (NH4)2SO4to spent catalysts mass ratio 7.5, roasting temperature 350℃, roasting time 5 h; and acid leaching conditions as follow: H2SO4 condition concentration 0.5 mol/L, leaching time 3h, leaching temperature 80℃, liquid to solid ratio 12.5, the enrichment of Pt is more than 274 times. Main mineral phase in the roasted product is NH4Al(SO4)2, the product was leached with acid, realizing enrichment and recovery of Pt by acid leaching.%采用铵盐焙烧-酸浸法进行了从石油重整废催化剂中富集回收铂的研究。结果表明,适宜的铵盐焙烧条件为:硫酸铵与废催化剂质量比为7.5,焙烧温度350℃,焙烧时间5 h;稀酸浸出条件:液固比12.5,浸出温度80℃,硫酸浓度为0.5 mol/L,浸出时间3 h。在上述条件下,铂的富集倍数达到274倍以上。通过XRD分析,焙烧产物的物相主要以硫酸铝铵形式存在,焙烧产物通过稀酸浸出,实现铂的富集回收。

  18. Study on arsenic removal from acid-leaching solution of zinc smelter slag with sulfide precipitation process%锌冶炼废渣浸出液硫化法除砷的研究

    Institute of Scientific and Technical Information of China (English)

    高峰; 贾永忠; 孙进贺; 景燕

    2011-01-01

    A method of using Na2S as precipitation reagent for eliminating arsenic from leaching solution of zinc smelter slag was studied. The effects of acidity, dosages of Na2S, reaction time and so on were investigated.The results indicated that the optimum conductions were as follows: the dosages of Na2S, 16.1 g/L( acid-leaching solution); H2SO4, 3 mol/L; reaction time, 30 min. The arsenic removal rate could reach 99.3% , so the method could prevent AsH3 gas efficiently in the process of extracting of indium.%以硫化钠为沉淀剂,将锌冶炼废渣浸出液中的砷以硫化砷的形式沉淀析出,实验考察了浸出液酸度、硫化钠加入量、反应时间等因素对除砷效率的影响.实验结果表明,当浸出液中游离H2SO4浓度为3 mol/L,Na2S·9H2O投加量为16.1 g/L(浸出液),反应时间为30 min时,浸出液中的砷去除率达到99.3%,较好地解决了在浸出液提铟过程中AsH3气体对环境的污染问题.

  19. In-situ uranium leaching

    International Nuclear Information System (INIS)

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

  20. Applications for biotechnology: present and future improvements in lactic acid bacteria.

    Science.gov (United States)

    McKay, L L; Baldwin, K A

    1990-09-01

    The lactic acid bacteria are involved in the manufacture of fermented foods from raw agricultural materials such as milk, meat, vegetables, and cereals. These fermented foods are a significant part of the food processing industry and are often prepared using selected strains that have the ability to produce desired products or changes efficiently. The application of genetic engineering technology to improve existing strains or develop novel strains for these fermentations is an active research area world-wide. As knowledge about the genetics and physiology of lactic acid bacteria accumulates, it becomes possible to genetically construct strains with characteristics shaped for specific purposes. Examples of present and future applications of biotechnology to lactic acid bacteria to improve product quality are described. Studies of the basic biology of these bacteria are being actively conducted and must be continued, in order for the food fermentation industry to reap the benefits of biotechnology.

  1. Hydrofluoric acid exposure: a case report and review on the clinical presentation and management.

    Science.gov (United States)

    Strausburg, Matthew; Travers, Jeffrey; Mousdicas, Nico

    2012-01-01

    Exposure to hydrofluoric acid can cause severe skin damage via both corrosive and chemical means. Dermatologists should be aware of the various clinical presentations and knowledgeable of how to manage such patients. A case of a man with exposure of the hands after use of a consumer product containing hydrofluoric acid is presented. The presentation may vary depending on the concentration and duration of exposure. Patients experiencing exposure are at risk of serious complications, including death, resulting from electrolyte abnormalities. Information regarding the source of exposure will allow the physician to better predict the patient's course. The use of immediate flushing with water and the use of topical calcium gluconate can prevent extensive damage to the area of exposure and potentially fatal complications that may occur. More extensive burns may necessitate more invasive therapies. The treatment and the management and monitoring of such cases will allow for more optimal outcomes.

  2. Recycling of spent lithium-ion battery cathode materials by ammoniacal leaching.

    Science.gov (United States)

    Ku, Heesuk; Jung, Yeojin; Jo, Minsang; Park, Sanghyuk; Kim, Sookyung; Yang, Donghyo; Rhee, Kangin; An, Eung-Mo; Sohn, Jeongsoo; Kwon, Kyungjung

    2016-08-01

    As the production and consumption of lithium ion batteries (LIBs) increase, the recycling of spent LIBs appears inevitable from an environmental, economic and health viewpoint. The leaching behavior of Ni, Mn, Co, Al and Cu from treated cathode active materials, which are separated from a commercial LIB pack in hybrid electric vehicles, is investigated with ammoniacal leaching agents based on ammonia, ammonium carbonate and ammonium sulfite. Ammonium sulfite as a reductant is necessary to enhance leaching kinetics particularly in the ammoniacal leaching of Ni and Co. Ammonium carbonate can act as a pH buffer so that the pH of leaching solution changes little during leaching. Co and Cu can be fully leached out whereas Mn and Al are hardly leached and Ni shows a moderate leaching efficiency. It is confirmed that the cathode active materials are a composite of LiMn2O4, LiCoxMnyNizO2, Al2O3 and C while the leach residue is composed of LiNixMnyCozO2, LiMn2O4, Al2O3, MnCO3 and Mn oxides. Co recovery via the ammoniacal leaching is believed to gain a competitive edge on convenitonal acid leaching both by reducing the sodium hydroxide expense for increasing the pH of leaching solution and by removing the separation steps of Mn and Al. PMID:27060219

  3. Determination of optimal conditions for pressure oxidative leaching of Sarcheshmeh Molybdenite concentrate using Taguchi method

    OpenAIRE

    Khoshnevisana A.; Yoozbashizadeha H.

    2012-01-01

    The present research work is based on finding the optimum conditions for pressure oxidative leaching of the molybdenite concentrate to produce technical-grade molybdic oxide (MoO3) with high recovery through further treatment of the filtrate solution. The Taguchi method was used to design and minimize the number of experiments. By using Taguchi orthogonal (L25) array, five parameters (time, temperature, oxygen pressure, pulp density and acid concentration) at five levels were selected f...

  4. Kinetics of Non-Catalytic Esterification of Free Fatty Acids Present in Jatropha Oil.

    Science.gov (United States)

    Prasanna Rani, Karna Narayana; Ramana Neeharika, Tulasi Sri Venkata; Kumar, Thella Prathap; Satyavathi, Bankupalli; Sailu, Chintha

    2016-05-01

    Non-catalytic esterfication of free fatty acids (FFA) present in vegetable oils is an alternative pretreatment process for the biodiesel production. Biodiesel, consists of long-chain fatty acid methyl esters (FAME) and is obtained from renewable sources such as vegetable oils or animal fat. This study presents kinetics of thermal esterification of free fatty acids present in jatropha oil with methanol. The effect of process parameters like reaction time (1-5 h), temperature (170-190°C) and oil to methanol ratio (1:3-1:5) at constant pressure was investigated. The optimal conditions were found to be oil to methanol ratio of 1:4, 190°C, at 27.1 bar and 5 h which gave a maximum conversion of 95.1%. A second order kinetic model for both forward and backward reactions was proposed to study the reaction system. A good agreement was observed between the experimental data and the model values. The activation energy for forward reaction and the heat of reaction were found to be 36.364 Kcal/mol and 1.74 Kcal/mol respectively. PMID:27086997

  5. 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.

  6. Anomalous transient leaching behavior of metals solidified/stabilized by pozzolanic fly ash

    Energy Technology Data Exchange (ETDEWEB)

    Camacho, Lucy Mar [Department of Chemical Engineering, New Mexico State University, Las Cruces, NM 88003 (United States)]. E-mail: lcamacho@nmsu.edu; Munson-McGee, Stuart H. [Department of Chemical Engineering, New Mexico State University, Las Cruces, NM 88003 (United States)

    2006-09-01

    This study presents observations on the transient leaching behavior of chromium, cadmium, and aluminum that were solidified/stabilized by pozzolanic fly ash. These three metals were selected since they were present in a simulated waste stream generated by an evaporator during plutonium purification and also because the minimum solubility of these metals occurs at significantly different pHs. The transient pH behavior of the toxicity characteristic leaching procedure (TCLP) leachate showed a monotonic increase for all cases, but the equilibrium value was affected by process conditions. The transient leachate concentration behavior showed curves with one or two local maxima for some cases and curves with a monotonic increase for other cases. Data from the leaching experiments was compared to the solubility curves for the hydroxides of each metal since it was assumed that the highly alkaline conditions inside the fly ash waste would cause the metals to precipitate as hydroxides after initially dissolving in the acidic leaching solution. It was found that of the three metals, only cadmium followed the solubility curve for pure hydroxide solutions or for fly ash systems currently reported in the literature.

  7. Resource Recovery of Magnesium Saponification Wastewater of Leaching Solution of Sulfuric Acid Calcining RE Concentrate%浓硫酸高温焙烧稀土精矿水浸液镁皂化废水的资源化

    Institute of Scientific and Technical Information of China (English)

    刘磊; 谢军; 李赫; 柳凌云; 侯少春; 萨如拉; 姚龙君

    2015-01-01

    研究了包头稀土精矿浓硫酸高温焙砂水浸液经过镁皂化萃取转型产生的镁皂废水的资源化全循环工艺,针对镁皂废水的净化除杂、晶体制备、晶体煅烧等进行了可行性研究。结果表明:控制草酸用量为理论量的2倍,镁皂废水的氧化钙质量浓度<0.2g/L ;净化后的镁皂废水经陶瓷膜过滤、纳滤膜浓缩得到的透析水可回用于水浸,浓水进入蒸发系统回收硫酸镁和冷凝水;冷凝水回用于水浸,硫酸镁晶体与碳粉在850℃下煅烧8 h可制备氧化镁;所得氧化镁的 CAA 活性值为109 s ,MgO 质量分数为96.84%,CaO 质量分数为0.52%,可用于生产稀土;硫酸镁煅烧产生的二氧化硫在钒触媒催化作用下可转化成70%的硫酸,回用于焙烧。该工艺可实现镁皂废水资源化全循环利用。%The resource recovery of magnesium saponification wastewater of leaching solution of sulfuric acid calcining rare earth concentrate was studied mainly involving the progresses of purification ,crystallization ,calcination and so on .T he experiment results show w hen the actual amount of oxalic acid is twice the theoretical amount ,the content of CaO in the magnesium saponification wastewater can be reduced to less than 2% .Then the dialysis water by ceramic membrane and nanofiltration membrane can be used in the process of RE leaching ,and the concentrate water can be used to recover magnesium sulfate and condensate water in evaporation system .The condensate water can used in the process of RE leaching .The magnesium sulfate crystal with carbon powder is calcinated for 8 h at 850 ℃ ,the magnesium oxide can be obtained .The analysis results show that in the magnesium oxide ,the content of MgO and CaO is 96 .84% and 0 .52% ,respectively .The value of CAA for the magnesium oxide is 109 s .Sulfur dioxide produced in the process of calcination can be conversed into 70% sulfuric acid used in the process

  8. 钛渣活化焙烧酸浸制备富钛料%Preparation of Ti-rich material from titanium slag by activation roasting followed by acid leaching

    Institute of Scientific and Technical Information of China (English)

    刘水石; 郭宇峰; 邱冠周; 姜涛; 陈凤

    2013-01-01

    A method of activation roasting followed by acid leaching using titanium slag was introduced to prepare Ti-rich material.The effects of H3PO4 dosage,roasting temperature,and roasting time on TiO2 grade were investigated.A Ti-rich material containing 88.54% TiO2,0.42% (CaO+MgO) was obtained when finely ground titanium slag was roasted with 7.5% H3PO4 at 1000 ℃ for 2 h,followed by a two-stage leaching in boiling dilute sulfuric acid for 2 h.The XRD patterns show that the product is titanium dioxide with a rutile structure.Mechanism studies show that structures of anosovite solid solution and silicate minerals are destroyed in the roasting process.As a result,titanium components in titanium slag are transformed into TiO2 (rutile) while impurities are transformed into acid-soluble phosphate and quartz.%提出了一种钛渣活化焙烧酸浸制备富钛料的方法,对磷酸用量、焙烧温度和焙烧时间对富钛料TiO2品位的影响进行研究.将细磨钛渣与7.5%磷酸在1000℃下焙烧2h,再将焙烧产物经过两段硫酸沸腾浸出,可获得TiO2品位为88.54%,CaO与MgO总量为0.42%的富钛料.经XRD鉴定,该富钛料主要物相为金红石结构的TiO2.机理研究表明,钛渣添加磷酸后焙烧,黑钛石固溶体结构和硅酸盐矿物结构遭到破坏,从而使钛渣中的钛组分转变为金红石物相,杂质组分转变为可酸溶的磷酸盐和石英.

  9. Evaluation of gold and silver leaching from printed circuit board of cellphones

    Energy Technology Data Exchange (ETDEWEB)

    Petter, P.M.H., E-mail: patymhp@yahoo.com.br; Veit, H.M.; Bernardes, A.M.

    2014-02-15

    Highlights: • Printed circuit boards (PCB) of mobile phones have large amounts of metals with high economic value such as gold and silver. • Dissolution of gold was done with a cyanide-based reagent and silver with nitric acid. • Leaching of PCB with Na{sub 2}S{sub 2}O{sub 3} and (NH{sub 4}){sub 2}S{sub 2}O{sub 3} to examine the feasibility of using these reagents was done. - Abstract: Electronic waste has been increasing proportionally with the technology. So, nowadays, it is necessary to consider the useful life, recycling, and final disposal of these equipment. Metals, such as Au, Ag, Cu, Sn and Ni can be found in the printed circuit boards (PCB). According to this, the aims of this work is to characterize the PCBs of mobile phones with aqua regia; obtaining “reference” values of leaching, to gold and silver, with cyanide and nitric acid, respectively; and study the process of leaching of these metals in alternative leaching with sodium thiosulfate and ammonium thiosulfate. The metals were characterized by digesting the sample with aqua regia for 1 and 2 h at 60 °C and 80 °C. The leaching of Au with a commercial reagent (cyanide) and the Ag with HNO{sub 3}were made. The leaching of Au and Ag with alternative reagents: Na{sub 2}S{sub 2}O{sub 3,} and (NH{sub 4}){sub 2}S{sub 2}O{sub 3} in 0.1 M concentration with the addition of CuSO{sub 4}, NH{sub 4}OH, and H{sub 2}O{sub 2}, was also studied. The results show that the digestion with aqua regia was efficient to characterize the metals present in the PCBs of mobile phones. However, the best method to solubilize silver was by digesting the sample with nitric acid. The leaching process using sodium thiosulfate was more efficient when an additional concentration of 0.015 and 0.030 M of the CuSO{sub 4} was added.

  10. 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.

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

    OpenAIRE

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

    2000-01-01

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

  12. Hydrothermal synthesis of NaY molecular sieve from coal-series kaolin by acid-leaching dealuminization%煤系高岭土酸浸脱铝水热合成NaY分子筛

    Institute of Scientific and Technical Information of China (English)

    蒋荣立; 陈文龙; 赵锐先; 王茜

    2012-01-01

    以煤系高岭土为原料,经煅烧、酸浸脱铝工艺,首次在酸浸偏高岭土-碱水热反应体系中合成了NaY分子筛.采用XRD,SEM对所合成样品进行表征,考察了体系中碱度、硅铝比、老化过程、晶化过程对NaY分子筛合成的影响.结果表明:该水热反应体系适宜的碱度条件为n(H2O)/n(Na2O)=80,碱度过高或过低均会出现P型分子筛杂相.适宜的硅铝配比为n(SiO2)/n(Al2O3)=6.4;老化有助于生成纯相、结晶度好的NaY分子筛,其适宜的老化温度为50℃、老化时间为4h.晶化温度过高或晶化时间过长易转晶生成P型杂相,适宜的晶化条件是晶化温度为85℃、晶化时间为24h.在该反应体系中反应原料由偏高岭土酸浸脱铝后获得,产物结晶度较高,无杂晶,晶形完整,粒度为2μm左右.%Taking coal-series kaolin as the material, the high-silica NaY molecular sieve was synthesized firstly in the hydrothermal reaction system of acid-leaching metakaolinite-alkali af- ter calcination and acid-leaching processes. The product was charactered by XRD and SEM. The effects of various hydrothermal conditions, including the molar ratios of n(SiO2)/ n(A12O3), aging process and crystallizing process on NaY molecular sieve synthesizing were in- vestigated. The results show that the proper alkalinity condition is molar ratios n(H20)/ n(Na2O)=80. The higher or lower alkalinity will cause molecular sieve impurity phase. The optimum n(SiO2)/n(A12O3) is 6.4. Theaging process contributes to generate pure and good crystallinity NaY molecular sieve, and the proper aging temperature and time are 50 ℃ and 4 h, respectively. The higher crystallizing temperature or longer crystallizing time will easily cause crystal transformation and yield P molecular sieve impurity phase. The proper crystalli- zing temperature and time are 85 ℃ and 24 h, respectively. The reaction material is easily yiel- ded by acid-leaching only once and the 2/

  13. 用N235从富铁高酸度硫酸浸出液中萃取除铁%Removal of Fe3+ from iron rich and high acidity sulfuric acid leaching liquid by extraction of N235

    Institute of Scientific and Technical Information of China (English)

    张魁芳; 刘志强; 曹洪杨; 邱显扬

    2015-01-01

    The extraction of Fe 3+ by N235 was studied based on the technology gap on the removal of Fe3+ from iron rich and high acidity sulfuric acid leaching liquid by extraction. The effects of H2O2 dosage, feed initial pH, extractant concentration, extractant composition and extraction time on the extraction, and the effects of H2SO4 concentration and tripping time on the stripping were investigated. The cross current extraction process was designed and the isotherms of stripping were plotted, and the conditions of extractant transformation were researched. The results show that, when 30% (mass fraction) H2O2 dosage is 3.85 times of theoretical one, Fe2+ can be oxidized into Fe3+ totally, and with 30% (volume fraction) N235 and10% (volume fraction) TBP in sulphonated kerosene as extractant, the extraction rate of Fe3+ from the solution with initial pH of 0.11reaches 96.67% in four-stage cross current extraction with O/A ratio of 1:1 (volume ratio of oil phase to aqueous phase) at 25℃ for 2 min, and the loss rate of Cu2+, Co2+, Ni2+ are 3.04%, 1.39%, 3.84%, respectively. The Fe3+ in loaded organic can be stripped into Fe2(SO4)3 with purity of 98.87% using 0.3 mol/L H2SO4 solution and the stripping rate reaches 99.12% in two-stage counter current stripping with O/A ratio of 1:1 (volume ratio of oil phase to aqueous phase) at 25℃ for 6 min. After stripping, the acid in loaded organic phase can be neutralized using Na2CO3. The organic phase returns to extraction circularly.%对N235萃取除铁进行研究,考察H 2 O 2用量、料液初始pH、萃取剂浓度、萃取剂组成、萃取时间对萃取的影响以及H2SO4浓度、反萃时间对反萃的影响,设计错流萃取过程并绘制反萃平衡等温线,对萃取剂转型条件进行研究。结果表明:H 2 O 2用量为理论量3.85倍时可将Fe2+完全氧化成Fe3+,并采用有机相组成30%(体积分数)N235+10%(体积分数)TBP+磺化煤油作为萃取剂,料液初始pH为0.11,其最佳萃

  14. 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/...

  15. 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.

  16. 可见分光光度计测定赤泥盐酸浸出液中的钪%Determination of scandium in hydrochloric acid leaching solution of red mud with visible spectrophotometer

    Institute of Scientific and Technical Information of China (English)

    李爱秀; 张晓芸

    2011-01-01

    用SP- 723PC可见分光光度计测定赤泥盐酸浸出液中的钪,考察了温度、时间、显色剂用量、酸度对待测溶液吸光度的影响.结果表明,温度对吸光度值影响较小,10 min后,显色完成,溶液颜色16 h内保持稳定,酸度对吸光度有较大的影响,最佳pH为2.0.溶液最大吸光度波长为650nm,Sc(Ⅲ)的质量浓度在0~1.2mg/L范围内符合朗伯-比尔定律,表观摩尔吸光系数为7.78×105 L· mol-1.cm-1.应用本法测定赤泥盐酸浸出液中的钪,结果重现性好,灵敏度高.%The scandium in hydrochloric acid leaching solution of red mud was determined with a SP-723 PC visible spectrophotometer. The effects of temperature, reaction time, coloring reagent quantity and pH on the absorbance of solution were investigated. It is showed that the temperature had weak effect on the absor-bance, color reaction completed in 10 min and the color of the solution maintained stable for 16h. But the pH value had stronger effect and the best pH value was 2. 0. The maximum absorbance is at 650nm. Lambert-Beer law is obeyed for Sc(Ⅲ) in the range of 0~12mg/L and the apparent molar absorptivity is 7. 78 ×l05L/(mol ? Cm). The method has been applied to the determination of Sc(Ⅲ) in hydrochloric acid leaching solution of red mud with good repeatability and high sensitivity.

  17. Chapter 3. Classical method of uranium leaching from ores and reasons for incomplete recovery at dumps of State Enterprise 'VOSTOKREDMET'. 3.3. Basic regularities of uranium ores leaching

    International Nuclear Information System (INIS)

    Present article is devoted to basic regularities of uranium ores leaching. It was found that the basic method of uranium ores enrichment and producing of reasonably rich and pure uranium concentrates (usually technical uranium oxide) is a chemical concentration concluded in selective uranium leaching from ore raw materials with further, uranium compounds - so called uranium chemical concentrates. Such reprocessing of uranium ores with the purpose of uranium chemical concentrates production, currently, are produced everywhere by hydrometallurgical methods. This method in comparison with enrichment and thermal reprocessing is a universal one. Hydrometallurgy - the part of chemical technology covering so called moist methods of metals and their compounds (in the current case, uranium) extraction from raw materials, where they are contained. It can be ores or ore concentrates produced by radiometric, gravitational, floatation enrichment, sometimes passed through high-temperature reprocessing or even industry wastes. The basic operation in hydrometallurgy is its important industrial element - metal or metals leaching as one or another compound. Leaching is conversion of one or several components to solution under impact of relevant technical solvents: water, water solutions, acids, alkali or base, solution of some salts and etc. The basic purpose of leaching in uranium technology is to obtain the most full and selective solution of uranium.

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

    Science.gov (United States)

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

    2015-09-01

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

  19. Winery vermicomposts to control the leaching of diuron, imidacloprid and their metabolites: role of dissolved organic carbon content.

    Science.gov (United States)

    Fernández-Bayo, Jesús D; Nogales, Rogelio; Romero, Esperanza

    2015-01-01

    Soil organic amendment addition is an effective practice in Mediterranean areas due to its associated high agricultural benefits and its potential to reduce the pesticide impact on water resources. However, their metabolites have received scarce attention, even when they may pose more risk than their parent compounds. Two winery vermicomposts obtained from spent grape marc (V1) and the mixture vine shoot-biosolid vinasses (V2) have been investigated as low cost organic amendments to minimize the leaching of diuron, imidacloprid and their metabolites in columns packed with a sandy loam (S1) and a silty-clay loam soil (S2) under steady state flow conditions. In the unamended soil columns, leached amounts of diuron were 75% and 53% in S1 and S2, respectively. Its metabolites (3-(3,4-dichlorophenyl)-1-methylurea, DPMU; and 3,4-dichlorophenylurea, DPU) percolated less than 35% of the total applied amount. The amount of the metabolite 3,4-dichloroaniline (DCA) was 2% and 30% for S1 and S2, respectively. Leaching of imidacloprid was 79% and 96% for S1 and S2, respectively, while its metabolite 6-chloronicotinic acid (CNA) was entirely leached. In the vermicompost-amended columns, the leaching of diuron was reduced 2 to 3-fold. DPMU and DPU were also significantly reduced (more than 6-fold). DCA did not appear in any of the leachates of the amended soil columns. Imidacloprid leaching was reduced 1 to 2-folds in the amended columns. The amendments did not affect the transport of CNA. The dissolved organic carbon (DOC) from the vermicomposts did not enhance pesticide transport throughout the soil in any case. This qualitative study presents these vermicomposts as an effective potential low-cost tool in reducing pesticide and metabolite leaching. The next step would be to test them under more realistic conditions. PMID:25602152

  20. Microbial leaching of iron from pyrite by moderate thermophile chemolithotropic bacteria

    International Nuclear Information System (INIS)

    The present work was aimed at studying the bioleachability of iron from pyrite by the selected moderately thermophilic strains of acidophilic chemolithotrophic and acidophilic heterotrophic bacteria. These included Sulfobacillus thermosulfidooxidans (chemolithotroph) and an un-identified strain of acidophilic heterotroph (code 6A1TSB) isolated from local environments. As compared to inoculated flasks, dissolution of metal (due to acid leaching) was significantly low in the un-inoculated control flasks in all the experiments in ore. A decrease in the bioleaching activity was observed at the later stages of bioleaching of metal from ore. Among the strategies adopted to enhance the metal leaching rates, a mixed consortium of the metal adapted cultures of the above-mentioned bacteria was found to exhibit the maximum metal leaching efficiency. In all the flasks where high metal leaching rates were observed, concomitantly biomass production rates were also high indicating high growth rates. It showed that the metal bioleaching capability of the bacteria was associated with their growth. Pyrite contained 42% iron. (author)

  1. Two-stage fungal leaching of vanadium from uranium ore residue of the leaching stage using statistical experimental design

    International Nuclear Information System (INIS)

    Highlights: ► In this work, the percent of vanadium recovery from uranium mine waste was 44.8. ► Unlike autotrophs, Aspergillus niger is a suitable microorganism to deal with such a resource. ► In the first step of the present work, citric acid was produced more than the other acids. ► When sterilization of uranium ore waste is not economic, two-step bioleaching is an appropriate method. - Abstract: In this investigation, bioleaching of vanadium from uranium ore residue of the leaching stage was studied by Aspergillus niger in a two-step process at 30 °C and 150 rpm. The first step was initiated by growth of fungi in the absence of mine waste. Using response surface methodology, three factors were surveyed for fungal growth: initial pH, sucrose concentration and spore population. Also concentrations of oxalic, citric, and gluconic acids were measured as response in this step. During 30 days, maximum productions of these acids were 3265, 11578, and 7988 mg/l, respectively. Initial pH and sucrose concentration were significant factors for oxalic and citric acid production; however, for gluconic acid production sucrose concentration and spore population were significant. Then, the content of each flask was filtered and mine waste was added to liquor with pulp density of 3%. During 3 days, in the second step, vanadium recovered about 44.8% in the liquor

  2. 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.

  3. The Effect of Simulated Acid Rain on the Leaching Behavior of Havy Metals from Brick Made in MSWI Lime - ash%模拟酸雨对污泥焚烧灰渣砖中重金属浸出影响

    Institute of Scientific and Technical Information of China (English)

    刘世宇; 童飞; 陈兴凡

    2012-01-01

    Bricks made in ted acid rain. Effect of soaking municipal sludge waste incineration (MSWI) lime - ash were soaked in kinks of simulatime of brick and pH of simulated acid rain on the leaching behavior of heavy metals from the bricks was investigated. Results showed that under the same dip in times, the total leaching concentration of 4 kinds of heavy metals was Cr, Mn, Cu and Fe, with the simulated acid rain pH accretion and drop. At the pH 4.4 of simulated acid rain, the order to leaching concentration of 4 kinds of heavy metals was Cr 〉 Mn 〉 Cu 〉 Fe, after 8 h dip in times. The total leaching concentration of Cd, Ni and Cu was lower than 0. 1 ppb, at the kinks of simulated acid rain.%用不同pH的模拟酸雨浸泡掺杂污泥焚烧灰渣自制的混凝土路面砖,探讨了相同浸泡时间时,模拟酸雨pH对自制路面砖中重金属浸出的影响。结果表明,在相同浸泡时间时,铬、锰、铜、铁的浸出浓度都随着模拟酸雨pH的增大而下降。在pH为4.4的模拟酸雨中,浸泡时间大于8小时后,铬、锰、铜、铁浸出浓度的大小关系是铬〉锰〉铜〉铁。而镉、镍、铅的浸出浓度在各种模拟酸雨中都小于0.1 ppb。

  4. A comparison of an optimised sequential extraction procedure and dilute acid leaching of elements in anoxic sediments, including the effects of oxidation on sediment metal partitioning

    International Nuclear Information System (INIS)

    The effect of oxidation of anoxic sediment upon the extraction of 13 elements (Cd, Sn, Sb, Pb, Al, Cr, Mn, Fe, Co, Ni, Cu, Zn, As) using the optimised Community Bureau of Reference of the European Commission (BCR) sequential extraction procedure and a dilute acid partial extraction procedure (4 h, 1 mol L-1 HCl) was investigated. Elements commonly associated with the sulfidic phase, Cd, Cu, Pb, Zn and Fe exhibited the most significant changes under the BCR sequential extraction procedure. Cd, Cu, Zn, and to a lesser extent Pb, were redistributed into the weak acid extractable fraction upon oxidation of the anoxic sediment and Fe was redistributed into the reducible fraction as expected, but an increase was also observed in the residual Fe. For the HCl partial extraction, sediments with moderate acid volatile sulfide (AVS) levels (1-100 μmol g-1) showed no significant difference in element partitioning following oxidation, whilst sediments containing high AVS levels (>100 μmol g-1) were significantly different with elevated concentrations of Cu and Sn noted in the partial extract following oxidation of the sediment. Comparison of the labile metals released using the BCR sequential extraction procedure (ΣSteps 1-3) to labile metals extracted using the dilute HCl partial extraction showed that no method was consistently more aggressive than the other, with the HCl partial extraction extracting more Sn and Sb from the anoxic sediment than the BCR procedure, whilst the BCR procedure extracted more Cr, Co, Cu and As than the HCl extraction

  5. Evaluation of the effectiveness of the filtration leaching for uranium recovery from uranium ore

    OpenAIRE

    Bolat Uralbekov; Mukhambetkaly Burkitbayev; Bagdat Satybaldiev

    2015-01-01

    The physical and chemical processes taking place in filtration leaching of uranium from uranium ore sample by sulphuric acid solution have been studied by modern physico-chemical methods (X-ray diffraction, scanning electron spectroscopy, electron probe microanalysis, optical emission spectroscope, ICP OES). Column leaching test was carried out for ore samples obtained from a uranium in-situ leaching (ISL) mining site using deluted sulphuricacid to study the evolution of various elements conc...

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

    Science.gov (United States)

    Xu, Ying; Chen, Yu

    2015-07-01

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

  7. Recovery of valuable metals from spent lithium-ion batteries by ultrasonic-assisted leaching process

    Science.gov (United States)

    Li, Li; Zhai, Longyu; Zhang, Xiaoxiao; Lu, Jun; Chen, Renjie; Wu, Feng; Amine, Khalil

    2014-09-01

    The anticipated significant use of lithium-ion batteries (LIBs) for energy storage applications in electric grid modernization and vehicle electrification shall generate a large quantity of solid waste that could become potential environmental hazards and waste natural resources. Recycling of the major components from spent LIBs is, therefore, considered desirable to prevent environmental pollution and to recycle valuable metals. This study reports on the application of ultrasonic-assisted technology to the leaching of cobalt and lithium from the cathode active materials of spent LIBs. Three acids were tested for the leaching process: two inorganic acids (H2SO4 and HCl) and one organic acid (citric acid, C6H8O7·H2O). The results show that the leaching of Co and Li is more efficient with citric acid than with the two inorganic acids. More than 96% Co and nearly 100% Li were recovered from spent LIBs. The optimal leaching conditions were 0.5 M citric acid with 0.55 M H2O2, a solid-to-liquid ratio of 25 g L-1, a temperature of 60 °C, leaching time of 5 h, and ultrasonic power of 90 W. The high leaching efficiency is mainly ascribed to the unique cavitation action of the ultrasonic waves. This ultrasonic-assisted leaching process with organic acid is not only effective but also environmentally friendly.

  8. Up-gradation of MoO3 and separation of copper, iron, zinc from roasted molybdenum ore by a leaching process

    International Nuclear Information System (INIS)

    The present research paper deals with the oxidation process of molybdenum ore. The main target of the present study is the up-gradation of MoO3 from roasted molybdenum ore by a leaching process without waste generation. The most important application of hydrometallurgical processing is the leaching process of the ore and it is the primary process to make pure metal from ore. The present investigations optimize the following experimental parameters to improve the concentration of MoO3 as well as the separation of copper, iron and zinc in roasted molybdenum ore: effect of acid concentration, temperature, pulp density and leaching time were studied systematically. The temperature study was carried out at 550-595 °C for the oxidation process. The XRD result shows that oxidation process of molybdenum ore and SEM pictures were taken for particles before and after the oxidation process at 585 °C for 360 min. (author)

  9. Up-gradation of MoO3 and separation of copper, iron, zinc from roasted molybdenum ore by a leaching process

    Directory of Open Access Journals (Sweden)

    Jin-Young Lee

    2013-06-01

    Full Text Available The present research paper deals with the oxidation process of molybdenum ore. The main target of the present study is the up-gradation of MoO3 from roasted molybdenum ore by a leaching process without waste generation. The most important application of hydrometallurgical processing is the leaching process of the ore and it is the primary process to make pure metal from ore. The present investigations optimize the following experimental parameters to improve the concentration of MoO3 as well as the separation of copper, iron and zinc in roasted molybdenum ore: effect of acid concentration, temperature, pulp density and leaching time were studied systematically. The temperature study was carried out at 550-595 ºC for the oxidation process. The XRD result shows that oxidation process of molybdenum ore and SEM pictures were taken for particles before and after the oxidation process at 585 ºC for 360 min.

  10. Up-gradation of MoO{sub 3} and separation of copper, iron, zinc from roasted molybdenum ore by a leaching process

    Energy Technology Data Exchange (ETDEWEB)

    Jin-Young, Lee; Jyothi Rajesh, Kumar; Ho-Seok, Jeon; Joon-Soo, Kim, E-mail: rajeshkumarphd@rediffmail.com, E-mail: rkumarphd@kigam.re.kr [Extractive Metallurgy Department, Mineral Resources Research Division, Korea Institute of Geoscience and Mineral Resources (KIGAM) (Korea, Republic of)

    2013-04-15

    The present research paper deals with the oxidation process of molybdenum ore. The main target of the present study is the up-gradation of MoO{sub 3} from roasted molybdenum ore by a leaching process without waste generation. The most important application of hydrometallurgical processing is the leaching process of the ore and it is the primary process to make pure metal from ore. The present investigations optimize the following experimental parameters to improve the concentration of MoO{sub 3} as well as the separation of copper, iron and zinc in roasted molybdenum ore: effect of acid concentration, temperature, pulp density and leaching time were studied systematically. The temperature study was carried out at 550-595 Degree-Sign C for the oxidation process. The XRD result shows that oxidation process of molybdenum ore and SEM pictures were taken for particles before and after the oxidation process at 585 Degree-Sign C for 360 min. (author)

  11. Kinetic investigations of oxidative roasting and afterwards leaching of copper-lead matte

    Directory of Open Access Journals (Sweden)

    Minić Duško

    2004-01-01

    Full Text Available In this paper, results of copper - lead matte investigations are presented. Investigated copper-lead matte is intermediate product of lead production in TREPCA-Zvecan. In the first part of the paper characterization of starting material is presented, consisting of: chemical composition analysis (XRQ, sceaning electron microscopy (SEM and diffractometry (XRD. Thermal properties of matte investigated were determined using differential thermal analysis (DTA at characteristic temperatures. Using results of induced analysis, mechanism of matte oxidation process was determined. In second part of the paper kinetic parameters describing oxidative roasting and afterwards leaching in sulfuric acid of copper-lead mate are presented.

  12. Economic leaching at Roessing Uranium Limited

    International Nuclear Information System (INIS)

    In the fourteen years that Roessing Uranium Limited has been in production, the metallurgical operations and controls on the leaching plant have envolved through four basic stages. Initially, the emphasis was placed on the achievement of consistent plant operation by overcoming severe start-up difficulties. The second stage involved the attainment of the design operating targets and also the commissioning of the ferric-leaching reactors in order to achieve a ferric ion concentration of more than 3.0 g/l. Improvements in control then became the priority, with the emphasis on consistently achieving the target concentrations of ferric ions, total iron, and terminal acidity. The latest phase has concentrated on the optimization of costs by means of adjustments to the historically established operating parameters in order to achieve large savings on consumables while maintaining the leaching efficiencies. Apart from the obvious incentive of reducing costs in an inflationary economy and a depressed uranium market, impetus for this work was given by a change in the type of ore from the open pit, which has the effect of reducing the extraction efficiency while increasing the consumption of consumable materials. These problems and their solutions are discussed in detail, and the importance to cost-effective optimization of an accurate up-to-date cost-reporting structure is stressed. 9 figs., 2 tabs

  13. Extraction and Recovery of Lead from Kaldo Slag by Acetate Acid and Sodium Acetate Leaching and Sodium Sulfite Precipitation%用乙酸-乙酸钠浸出及亚硫酸钠沉淀分离回收卡尔多炉渣中的铅

    Institute of Scientific and Technical Information of China (English)

    吕建军; 肖连生; 张启修; 黄芍英; 胡磊; 曾之琪

    2013-01-01

    采用乙酸-乙酸钠溶液浸出卡尔多炉渣中的铅,用无水亚硫酸钠沉淀分离浸出液中的铅,沉铅滤液脱硫(加氢氧化钡)后返回浸出工序,研究了相关工艺参数对铝直收率及亚硫酸铅纯度的影响.结果表明:在搅拌速度为300 r/min,浸出温度为室温(25℃),乙酸、乙酸钠浓度分别为1 mol/L和2 mol/L,液固比5∶1,浸出时间2h时,铅的浸出率可达到99.1%,浸出液含铅78.3 g/L;在搅拌速度200 r/min,沉淀温度为室温(25℃),无水亚硫酸钠过量系数1.25,沉淀时间20 min时,沉铅滤液余铅含量可降至4×10-6,亚硫酸铅纯度达到97.4%,铅的直收率可达到98%以上;沉铅滤液除硫酸根后,补充乙酸、乙酸钠至摩尔浓度分别为1mol/L和2 mol/L,返回浸出工序,按浸出的最优条件处理同样的卡尔多炉渣,铅的浸出率可以达到98.1%,实现了浸出剂的闭路循环.%Lead was leached from Kaldo slag using acetate acid and sodium acetate, then precipitated and extracted from the leaching liquor by sodium sulfite. The lead-extracted filtrate was returned to the leaching process after being desulfurized by barium hydroxide. The effects of related process parameters on aluminum recovery and lead sulfite purity were investigated. The results show that under the conditions such as stirring speed of 300 r/min, leaching temperature of 251, acetate acid concertration of 1 mol/L, sodium acetate concertration of 2 mol/L, liquid-solid ratio of 5:1 and leaching time of 2 h, the leaching rate of lead can reach to 99.1%, with a lead content of 78.3 g/L in the leaching liquor. Under the following conditions; stirring speed of 200 r/min, precipitation temperature of 25 ℃, an excess coefficient of hydrous sodium sulfite of 1.25 and precipitation time of 20 min, the lead content in the lead-extracted filtrate can be decreased to 4 × 10-6 while the purity of lead sulfite and lead recovery reaches to 97.4% and 98% respectively. After desulfurization

  14. 熔剂精炼结合湿法处理提纯冶金级硅的研究进展%Latest Progress in Purification of Metallurgical Grade Silicon by Solvent Refining and Subsequent Acid Leaching

    Institute of Scientific and Technical Information of China (English)

    陆海飞; 魏奎先; 马文会; 谢克强; 伍继君; 雷云; 戴永年

    2015-01-01

    冶金级硅是生产多晶体硅的主要原料,而多晶硅主要用于太阳电池的制备。为了满足制备太阳电池的条件,需精炼冶金级硅以降低其中的杂质含量。熔剂精炼是一种相对能耗低,在杂质硼、磷去除方面具有一定优势的冶金级硅提纯技术,将熔剂精炼和酸浸处理结合起来的方法能进一步提高冶金级硅的提纯效果,对制备低成本太阳能级多晶硅具有重要影响。对目前熔剂精炼提纯冶金级硅的最新研究进展作了较为全面的阐述,详细介绍了国内外研究人员采用 Ca-Si、Al-Si、Sn-Si、Cu-Si 等熔剂体系精炼去除冶金级硅中杂质的方法、工艺及效果。采用熔剂精炼结合湿法处理提纯冶金级硅,通过调控析出成分,使得金属杂质或非金属杂质间形成易于在晶界处沉淀析出并溶于酸的化合物,实现熔剂精炼与湿法处理对杂质的强化析出及协同去除。最后对熔剂精炼结合湿法处理提纯冶金级硅进行了总结并对其发展做出展望。%Metallurgical grade silicon(MG-Si)is the essential raw material for producing polycrystalline silicon, which is mainly used for the preparation of solar cells.MG-Si should be refined to reduce the impurity contend to be appropriate for the preparation of solar cells.Solvent refining is a low-energy consumption purification technology which is good at removing impurities such as boron and phosphorus in MG-Si.If combine with the acid leaching treat-ment with the solvent refining method,the purification effect of MG-Si will be improved,and this can reduce the cost for the solar polysilicon industry.The latest progress in purification of MG-Si by solvent refining is comprehensively described,and the purification of MG-Si is introduced in detail,such as the Ca-Si,Al-Si,Sn-Si,Cu-Si solvent sys-tem.MG-Si can be purified by employing the method of solvent refining and subsequent acid leaching.The key work is to adjust

  15. Study on leaching of refractory uranium in clay

    International Nuclear Information System (INIS)

    The leaching characteristcs of uranium-bearing clay of deposit A and other uranium deposits ar described. The causes of leaching refractoriness of the uranium in clay have been discussed. The research results show that the reason of leaching refractoriness of the uranium in clay is associated with recryctallization of clay minerals (including opel and goethite) during metamorphism of rocks. The probable course of forming refractory uranium in clay may be: adsorption of U+6 by clay minerals; reduction of U+6 to U+4; recrystalization of the clay mineral and U+4 exists at closed or semi-closed state in it. The results show that in order to leach the refractory uranium in clay, the uranium-bearing mineral should be made to produce new faultiness for reopening the passages into the mineral, thereby the uranium existing at closed or semi-closed state is exposed, and at the same time U+4 is oxidized to U+6. The middle-low temperature oxidation roasting, pressure alkaline leaching (160-180 deg C), and leaching with concentrated acid are efficient in treating the refractory type uranium ore

  16. Analysis of SPR salt cavern remedial leach program 2013.

    Energy Technology Data Exchange (ETDEWEB)

    Weber, Paula D.; Gutierrez, Karen A.; Lord, David L.; Rudeen, David Keith

    2013-09-01

    The storage caverns of the US Strategic Petroleum Reserve (SPR) exhibit creep behavior resulting in reduction of storage capacity over time. Maintenance of oil storage capacity requires periodic controlled leaching named remedial leach. The 30 MMB sale in summer 2011 provided space available to facilitate leaching operations. The objective of this report is to present the results and analyses of remedial leach activity at the SPR following the 2011 sale until mid-January 2013. This report focuses on caverns BH101, BH104, WH105 and WH106. Three of the four hanging strings were damaged resulting in deviations from normal leach patterns; however, the deviations did not affect the immediate geomechanical stability of the caverns. Significant leaching occurred in the toes of the caverns likely decreasing the number of available drawdowns until P/D ratio criteria are met. SANSMIC shows good agreement with sonar data and reasonably predicted the location and size of the enhanced leaching region resulting from string breakage.

  17. 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.

  18. Determination of optimal conditions for pressure oxidative leaching of Sarcheshmeh Molybdenite concentrate using Taguchi method

    Directory of Open Access Journals (Sweden)

    Khoshnevisana A.

    2012-01-01

    Full Text Available The present research work is based on finding the optimum conditions for pressure oxidative leaching of the molybdenite concentrate to produce technical-grade molybdic oxide (MoO3 with high recovery through further treatment of the filtrate solution. The Taguchi method was used to design and minimize the number of experiments. By using Taguchi orthogonal (L25 array, five parameters (time, temperature, oxygen pressure, pulp density and acid concentration at five levels were selected for 25 experiments. The experiments were designed and carried out in a high-pressure reactor in the presence of nitric acid as solvent and oxidizing agent for the molybdenite concentrate and its ReS2 content. The optimum conditions for pressure leaching of molybdenite were obtained through using Signal to Noise analysis and modified by using Minitab software prediction tool. Furthermore, the optimum condition for an economical pressure leaching of rhenium sulfide (ReS2 was achieved with the same process. Analysis of variance (ANOVA showed that the pulp density is of paramount importance in this process.

  19. Triterpenic Acids Present in Hawthorn Lower Plasma Cholesterol by Inhibiting Intestinal ACAT Activity in Hamsters

    OpenAIRE

    Yuguang Lin; Vermeer, Mario A.; Trautwein, Elke A.

    2010-01-01

    Hawthorn (Crataegus pinnatifida) is an edible fruit used in traditional Chinese medicine to lower plasma lipids. This study explored lipid-lowering compounds and underlying mechanisms of action of hawthorn. Hawthorn powder extracts inhibited acylCoA:cholesterol acyltransferase (ACAT) activity in Caco-2 cells. The inhibitory activity was positively associated with triterpenic acid (i.e., oleanolic acid (OA) and ursolic acid (UA)) contents in the extracts. Cholesterol lowering effects of hawtho...

  20. Using S and Pb isotope ratios to trace leaching of toxic substances from an acid-impacted industrial-waste landfill (Pozdatky, Czech Republic)

    International Nuclear Information System (INIS)

    Highlights: ► S and Pb isotopes are useful tracers of polluted groundwater movement. ► Large ranges of found δ34S and 206Pb/207Pb ratios made source apportionment robust. ► δ34S values higher than 6.5 permil indicated contamination. ► Pb in stream sediment recorded landfill leaks, but was insensitive to air pollution. ► The front of polluted groundwater plume in fractured plutonic rocks spread unevenly. - Abstract: Slightly elevated concentrations of toxic species in waters sampled in the surroundings of a leaky landfill may be both a sign of an approaching contaminant plume, or a result of water–rock interaction. Isotopes can be instrumental in distinguishing between anthropogenic and geogenic species in groundwater. We studied sulfur and lead isotope ratios at an abandoned industrial-waste landfill, located in a densely populated part of Central Europe. Stable isotope variability in space and time was used to follow the movement of a groundwater plume, contaminated with toxic metals (Cd, Cr, Be), in fractured granitoids. Toxic metals had been mobilized from industrial waste by a strong pulse of sulfuric acid, also deposited in the landfill. Both tracers exhibited a wide range of values (δ34S between +2.6 and +18.9‰; 206Pb/207Pb between 1.16 and 1.39), which facilitated identification of mixing end-members, and made it possible to assess the sources of the studied species. In situ fractionations did not hinder source apportionment. Influx of contaminated groundwater was observed neither in irrigation wells in a nearby village, nor at distances greater than 300 m from the landfill. Combination of stable isotope tracers can be used as part of an early-warning system in landscapes affected by landfills.

  1. 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.

  2. Unique odd-chain polyenoic phospholipid fatty acids present in chytrid fungi.

    Science.gov (United States)

    Akinwole, Philips O; Lefevre, Emilie; Powell, Martha J; Findlay, Robert H

    2014-09-01

    Chytrid fungi are ubiquitous components of aquatic and terrestrial ecosystems yet they remain understudied. To investigate the use of phospholipid fatty acids as phenotypic characteristics in taxonomic studies and biomarkers for ecological studies, 18 chytrid fungi isolated from soil to freshwater samples were grown in defined media and their phospholipid fatty acid profile determined. Gas chromatographic/mass spectral analysis indicated the presence of fatty acids typically associated with fungi, such as 16:1(n-7), 16:0, 18:2(n-6), 18:3(n-3) 18:1(n-9), and 18:0, as well as, a number of odd-chain length fatty acids, including two polyunsaturated C-17 fatty acids. Conversion to their 3-pyridylcarbinol ester facilitated GC-MS determination of double-bond positions and these fatty acid were identified as 6,9-17:2 [17:2(n-8)] and 6,9,12-17:3 [17:3(n-5)]. To the best of our knowledge, this is the first report of polyunsaturated C-17 fatty acids isolated from the phospholipids of chytrid fungi. Cluster analysis of PLFA profiles showed sufficient correlation with chytrid phylogeny to warrant inclusion of lipid analysis in species descriptions and the presence of several phospholipid fatty acids of restricted phylogenetic distributions suggests their usefulness as biomarkers for ecological studies. PMID:25119485

  3. Experimental study on the extraction of scandium from the sulfuric acid leach solution of red mud%赤泥硫酸浸出液中钪的萃取试验研究

    Institute of Scientific and Technical Information of China (English)

    池丕华; 赵孟珊; 刘丹丹; 张春生; 王学哲; 李京; 韩治纬

    2016-01-01

    In this paper,P204 extraction experimental study is carried out according to the property of the high-pressure sulfuric acid leach solution of red mud.The experiment investigated the influence that different extractant MVF,extraction temperature,and sulfuric acid concentration in water phase have on the extraction separation of scan-dium and iron, and optimum conditions were obtained, namely the extraction temperature of 35 ℃, extraction agent concentration of 5 %,O/A =1∶3,time of 15 min,rotation speed of 230 r/min and 10-stage extraction; under the conditions,the separation effect of scandium and iron is satisfactory with scandium extraction rate of 92.10%and iron extraction rate of 1.13%.After 10-stage cleansing by hydrochloric acid of loaded organic phase,removal rate of iron, as impurity,is 97.88 %and loss rate of scandium is 0.24 %.The results show that P204 is effective in separation of scandium and iron in extraction solutions.%针对赤泥的硫酸高压浸出液的性质,进行了P204萃取试验研究。通过考察萃取剂体积分数、萃取温度、水相中硫酸浓度等因素对钪、铁萃取分离的影响,得出了最佳萃取条件为萃取温度35℃,水相硫酸浓度4 mol/L,萃取剂体积分数5%,O/A=1∶3,萃取时间15 min,转速230 r/min,10级萃取;在最佳条件下,钪、铁分离效果较好,钪萃取率为92.10%、铁萃取率为1.13%。负载有机相经10级4 mol/L盐酸洗涤,杂质Fe的去除率为97.88%,钪损失率为0.24%;这表明P204能够很好地将萃取原液中的钪与杂质金属铁分离。

  4. 模拟酸雨对赣南稀土矿淋滤实验研究%Leaching experiments on rare earth ore in Southern Jiangxi under condition of simulated acid rain

    Institute of Scientific and Technical Information of China (English)

    温春辉; 刘祖文; 张念; 徐春燕; 张旭东

    2016-01-01

    采用模拟土柱淋滤实验研究酸雨条件下浸矿土壤和尾矿土壤中氮化物的迁移.选取有机玻璃管为试验柱,模拟酸雨淋滤液pH为5.4~5.6,测量两类土壤中NH4+-N、NO3--N、有效氮含量,实验结果表明:稀土土壤对铵态氮有一定截留作用,铵态氮流失是导致矿区土壤及周边水环境污染的主要原因;铵态氮在两类土壤的含量随着淋洗量增加而逐渐减少;硝态氮在两类土壤的含量随着淋洗量增加呈现先减少至最低再有所回升,且受土壤pH和土壤埋深影响;有效氮在两类土壤中的迁移特征与铵态氮相似.实验研究为有效控制赣南稀土矿土壤污染和水体污染提供理论基础.%The leaching mine and tailings migration of nitrogen in the soil were studied by simulation of soil column and leaching experiment under the condition of acid rain. The organic glass tube was chosen for testing column, the pH value of acid rain drench filtrate was simulated at 5.4~5.6, and the two types of NH4+-N, NO3--N, and effective nitrogen content in the soil were measured. The experimental results show that the rare earth soil play a certain role in entrapment of ammonia nitrogen and ammonium nitrogen loss, which is the main cause of water pollution in mining area and the surrounding soil. Ammonia nitrogen in the two types of the content of the soil reduce gradually as the elution volume increases. The NO3--N in the two types of the content of soil re-duce to a minimum first then recovered with elution volume rendering increase, and it is affected by soil pH and soil depth. The characteristics of effective nitrogen migration in two kinds of soil are similar to ammonia nitrogen. Experimental study provides the theoretical foundation for the effective control soil pollution and wa-ter pollution of the rare earth ores in Southern Jiangxi.

  5. Leaching of a copper flotation concentrate with ammonium persulfate in an autoclave system

    Institute of Scientific and Technical Information of China (English)

    M Deniz Turan; H Soner Altundoan

    2014-01-01

    The leaching behavior of a copper flotation concentrate was investigated using ammonium persulfate (APS) in an autoclave sys-tem. The decomposition products of APS, active oxygen, and acidic medium were used to extract metals from the concentrate. Leaching ex-periments were performed to compare the availability of APS as an oxidizing agent for leaching of the concentrate under atmospheric condi-tions and in an autoclave system. Leaching temperature and APS concentration were found to be important parameters in both leaching sys-tems. Atmospheric leaching studies showed that the metal extractions increased with the increase in APS concentration and temperature (up to 333 K). A similar tendency was determined in the autoclave studies up to 423 K. It was also determined that the metal extractions de-creased at temperatures above 423 K due to the passivation of the particle surface by molten elemental sulfur. The results showed that higher copper extractions could be achieved using an autoclave system.

  6. Influence of several experimental parameters on As and Se leaching from coal fly ash samples

    Energy Technology Data Exchange (ETDEWEB)

    Otero-Rey, Jose R. [Department of Analytical Chemistry, Faculty of Sciences, University of A Coruna, Campus da Zapateira s/n, E-15071 A Coruna (Spain); Mato-Fernandez, Maria J. [Department of Analytical Chemistry, Faculty of Sciences, University of A Coruna, Campus da Zapateira s/n, E-15071 A Coruna (Spain); Moreda-Pineiro, Jorge [Department of Analytical Chemistry, Faculty of Sciences, University of A Coruna, Campus da Zapateira s/n, E-15071 A Coruna (Spain); Alonso-Rodriguez, Elia [Department of Analytical Chemistry, Faculty of Sciences, University of A Coruna, Campus da Zapateira s/n, E-15071 A Coruna (Spain)]. E-mail: elia@udc.es; Muniategui-Lorenzo, Soledad [Department of Analytical Chemistry, Faculty of Sciences, University of A Coruna, Campus da Zapateira s/n, E-15071 A Coruna (Spain); Lopez-Mahia, Purificacion [Department of Analytical Chemistry, Faculty of Sciences, University of A Coruna, Campus da Zapateira s/n, E-15071 A Coruna (Spain); Prada-Rodriguez, Dario [Department of Analytical Chemistry, Faculty of Sciences, University of A Coruna, Campus da Zapateira s/n, E-15071 A Coruna (Spain)

    2005-02-28

    Coal fly ash leaching process for As and Se is studied. Environmental parameters such as pH, temperature, solid-liquid ratio, particle size and leaching time are taken into account in order to simulate As and Se leaching process for disposal coal fly ash. Analysis of reference materials was carried out by using of hydride generation coupled to atomic fluorescence spectrometry. Plackett-Burman experimental design is used to know the significative parameters, and Box-Behnken experimental design is used to refine the results obtained for these significative parameters. pH and temperature shown a hardly influence in leaching process. Furthermore, leaching time was also significative. According our results, it may be assumed that percentage of As and Se leaching in experimental conditions tested is relatively low for acidic fly ashes.

  7. Detoxification of mercury pollutant leached from spent fluorescent lamps using bacterial strains.

    Science.gov (United States)

    Al-Ghouti, Mohammad A; Abuqaoud, Reem H; Abu-Dieyeh, Mohammed H

    2016-03-01

    The spent fluorescent lamps (SFLs) are being classified as a hazardous waste due to having mercury as one of its main components. Mercury is considered the second most toxic heavy metal (arsenic is the first) with harmful effects on animal nervous system as it causes different neurological disorders. In this research, the mercury from phosphor powder was leached, then bioremediated using bacterial strains isolated from Qatari environment. Leaching of mercury was carried out with nitric and hydrochloric acid solutions using two approaches: leaching at ambient conditions and microwave-assisted leaching. The results obtained from this research showed that microwave-assisted leaching method was significantly better in leaching mercury than the acid leaching where the mercury leaching efficiency reached 76.4%. For mercury bio-uptake, twenty bacterial strains (previously isolated and purified from petroleum oil contaminated soils) were sub-cultured on Luria Bertani (LB) plates with mercury chloride to check the bacterial tolerance to mercury. Seven of these twenty strains showed a degree of tolerance to mercury. The bio-uptake capacities of the promising strains were investigated using the mercury leached from the fluorescent lamps. Three of the strains (Enterobacter helveticus, Citrobacter amalonaticus, and Cronobacter muytjensii) showed bio-uptake efficiency ranged from 28.8% to 63.6%. PMID:26725036

  8. Study on leaching vanadium from roasted residue of stone coal

    Energy Technology Data Exchange (ETDEWEB)

    He, D.; Feng, Q.; Zhang, G.; Luo, W.; Ou, L. [Central South University, Changsha (China)

    2008-11-15

    In China, the total reserves of vanadium, reported as V{sub 2}O{sub 5}, in stone coal is 118 Mt (130 million st). Recovering vanadium from such a large resource is very important to China's vanadium industry. The technology now being used to recover vanadium from stone coal has the following two problems in the leaching process: a low recovery of vanadium and high acid consumption. To resolve these problems, a new leaching technology is proposed. The effects of factors such as H{sub 2}SO{sub 4} concentration, liquid-solid ratio, temperature and time, and the types and additions of additives were studied. By adding 1.5% (by weight) CaF2 and leaching the roasted residue of stone coal with 5.4% (by weight) sulfuric acid at 90{sup o}C for 12 hours at a liquid-solid ratio of 2 mL/g, the leaching degree of vanadium reached 83.10%. This proposed leaching technology gives a feasible alternative for the processing of roasting residue of stone coal and can be applied in the comprehensive utilization of stone coal ores in China.

  9. Literature Survey Concerning the Feasibility of Remedial Leach for Select Phase I Caverns

    Energy Technology Data Exchange (ETDEWEB)

    Weber, Paula D. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Flores, Karen A. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Lord, David L. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2015-09-01

    Bryan Mound 5 ( BM5 ) and West Hackberry 9 ( WH9 ) have the potential to create a significant amount of new storage space should the caverns be deemed "leach - ready". This study discusses the original drilling history of the caverns, surrounding geology, current stability, and, based on this culmination of data, makes a preliminary assessment of the leach potential for the cavern. The risks associated with leaching BM5 present substantial problems for the SPR . The odd shape and large amount of insoluble material make it difficult to de termine whether a targeted leach would have the desired effect and create useable ullage or further distort the shape with preferential leaching . T he likelihood of salt falls and damaged or severed casing string is significant . In addition, a targeted le ach would require the relocation of approximately 27 MMB of oil . Due to the abundance of unknown factors associated with this cavern, a targeted leach of BM5 is not recommended. A targeted leaching of the neck of WH 9 could potentially eliminate or diminis h the mid - cavern ledge result ing in a more stable cavern with a more favorable shape. A better understanding of the composition of the surrounding salt and a less complicated leaching history yields more confidence in the ability to successfully leach this region. A targeted leach of WH9 can be recommended upon the completion of a full leach plan with consideration of the impacts upon nearby caverns .

  10. Hydrometallurgical recovery of copper from leach liquor of polymetallic nodules in solvent extraction process

    Directory of Open Access Journals (Sweden)

    B. Pospiech

    2012-12-01

    Full Text Available Purpose: Purpose of this paper is to present the possibilities of copper(II recovery from the synthetic sulphate leach liquor containing cobalt(II, nickel(II and manganese(II.Design/methodology/approach: The investigations have been undertaken in order to determine the influence of major parameters on the extraction process of copper(II from the leach liquor of polymetallic manganese nodules. Copper(II ions were extracted with Kelex 100 and LIX 70 in kerosene. The effect of different parameters such as pH of aqueous phase, extractants concentration in the organic phase, concentration of sulphuric acid as the stripping reagent were investigated.Findings: The optimal conditions of metal ions selectivity extraction have been determined. Over 99% of Cu(II can be effectively extracted with 5% Kelex 100 and 10% LIX 70 at pH of 2.0 from model leach liquor in the presence of Co(II, Ni(II and Mn(II, while less than 10% of the other metals is transported to the organic phase. The selectivity of Cu(II extraction over Co(II, Ni(II and Mn(II with Kelex 100 depended upon the acidity of aqueous solution and the selectivity increased with decreasing of pH in the feed solution. Separation of Cu(II from these metal ions is very effective. Cu(II can be recovered successfully from the loaded organic phase with Kelex 100 through stripping with 2.0 M H2SO4.Practical implications: The results can be used during the hydrometallurgical recovery of metals from nodules on the industrial scale.Originality/value: The study on the solvent extraction of Cu(II using LIX 70 and Kelex 100 from leach liquor of polymetallic manganese nodules has not been reported yet. Conducting this research is therefore the most reasonable and necessary.

  11. Phosphorus leaching from cow manure patches on soil columns

    NARCIS (Netherlands)

    Chardon, W.J.; Aalderink, G.H.; Salm, van der C.

    2007-01-01

    The loss of P in overland flow or leachate from manure patches can impair surface water quality. We studied leaching of P from 10-cmhigh lysimeters filled with intact grassland soil or with acid-washed sand. A manure patch was created on two grassland and two sandfilled lysimeters, and an additional

  12. Leaching of trace elements from coal solid waste

    International Nuclear Information System (INIS)

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

  13. Ferric Sulfate Leaching of Pyrrhotite Tailings between 30 to 55 °C

    Directory of Open Access Journals (Sweden)

    Nazanin Samadifard

    2015-11-01

    Full Text Available Mine tailings present major environmental issues in the mining industry. However due to the depletion of high-grade sulfide ores for metal recovery, tailings could also be a potential resource for certain valuable metals. The present study investigates the potential to recover nickel from pyrrhotite tailings. Leaching tests were performed in acidic ferric sulfate media with 0.14 wt % solids to keep the ferric concentration essentially constant. The temperature was varied between 30 and 55 °C, and the ferric concentration was in a range 0.02–0.3 M. The results showed that both temperature and ferric sulfate concentration had significant effects on the nickel extraction kinetics. The shrinking core model (SCM was applied to the nickel extraction data. The rate controlling step was found to be product layer diffusion. The Arrhenius plot yielded an activation energy of Ea = 62.12 kJ/mol based on apparent reaction rates obtained by the SCM. The reaction order with respect to ferric ion was found to be 1 at the high concentration range. SEM images of partially leached tailings confirmed the presence of elemental sulfur around the pyrrhotite particles, which was responsible for the observed non-linear leaching kinetics (diffusion control.

  14. Static leaching of uraniferous shales on open areas; Lixiviacion estatica de izarras uraniferas (tratamiento de mineral rico en era abierta)

    Energy Technology Data Exchange (ETDEWEB)

    Hernandez Nieto, J.; Cordero, G.; Villarrubia, M.

    1973-07-01

    This report describes the tests on acid heap leaching with conventional (1.400 ppm U{sub 3}O{sub 8}) crushed uranium ores. We use open circuits with low internal recycled. Using starving acidity in the leaching solutions we obtain a smooth solubilization of uranium and, at the same time, the pregnant liquors are good for the solvent extraction recovery. (Author)

  15. Development of an extractive spectrophotometric method for estimation of uranium in ore leach solutions using 2-ethylhexyl phosphonic acid-mono-2-ethylhexyl ester (PC88A) and tri-n-octyl phosphine oxide (TOPO) mixture as extractant and 2-(5-bromo-2-pyridylozo)-5-diethyl aminophenol (Br-PADAP) as chromophore.

    Science.gov (United States)

    Biswas, Sujoy; Pathak, P N; Roy, S B

    2012-06-01

    An extractive spectrophotometric analytical method has been developed for the determination of uranium in ore leach solution. This technique is based on the selective extraction of uranium from multielement system using a synergistic mixture of 2-ethylhexyl phosphonic acid-mono-2-ethylhexyl ester (PC88A) and tri-n-octyl phosphine oxide (TOPO) in cyclohexane and color development from the organic phase aliquot using 2-(5-Bromo-2-pyridylazo)-5-diethyl aminophenol (Br-PADAP) as chromogenic reagent. The absorption maximum (λ(max)) for UO(2)(2+)-Br-PADAP complex in organic phase samples, in 64% (v/v) ethanol containing buffer solution (pH 7.8) and 1,2-cyclohexylenedinitrilotetraacetic acid (CyDTA) complexing agent, has been found to be at 576 nm (molar extinction coefficient, ɛ: 36,750 ± 240 L mol(-1)cm(-1)). Effects of various parameters like stability of complex, ethanol volume, ore matrix, interfering ions etc. on the determination of uranium have also been evaluated. Absorbance measurements as a function of time showed that colored complex is stable up to > 24h. Presence of increased amount of ethanol in colored solution suppresses the absorption of a standard UO(2)(2+)-Br-PADAP solution. Analyses of synthetic standard as well as ore leach a solution show that for 10 determination relative standard deviation (RSD) is uranium using standard addition method and was found to be accurate with a 98-105% recovery rate. The developed method has been applied for the analysis of a number of uranium samples generated from uranium ore leach solutions and results were compared with standard methods like inductively coupled plasma emission spectrometry (ICPAES). The determined values of uranium concentrations by these methods are within ± 2%. This method can be used to determine 2.5-250 μg mL(-1) uranium in ore leach solutions with high accuracy and precision. PMID:22381794

  16. 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.

  17. 硫酸铅在柠檬酸钠-乙酸体系中的浸出转化%Leaching and desulphurisation of PbSO4 in sodium citrate and acetic acid solution

    Institute of Scientific and Technical Information of China (English)

    刘玲静; 何雄; 朱新锋; 李磊; 杨丹妮; 杨家宽

    2013-01-01

    硫酸铅可以在柠檬酸钠-乙酸体系中脱硫转化生成柠檬酸铅.考察了柠檬酸钠投加量、反应时间、固液比以及反应温度对PbSO4浸出转化的影响.实验结果表明,PbSO4的转化率随着柠檬酸钠投加量和反应时间的增加而增大,固液比和反应温度对浸出过程影响不大.溶液中溶解的铅含量随着柠檬酸钠投加量的增大而增大,其他条件对其影响不明显.最佳浸出工艺条件是:柠檬酸钠与PbSO4的物质的量之比为2:1,固液比为1/5~ 1/3,反应温度为25℃,反应时间为2h,此时PbSO4的转化率可达到99%左右,溶液中的铅含量为总铅的3.8%左右.PbSO4浸出得到[Pb3(C6H5O7)2]·3H2O,它在350℃左右可完全分解,得到PbO/Pb粉末.%In this study, to achieve lead recovery simultaneously with desulphurization, PbSO4 were reacted with sodium citrate and acetic acid in aqueous media, and lead was recovered as lead citrate in this process. Optimal leaching conditions were determined by investigating the effect of concentration, reaction time, the initial PbSO4/water and temperature. The results show that the conversion rate of PbSO4 in the solution increases with the increase of the concentration of sodium citrate and reaction time, while other factors show no significant effects. The remaining lead content in the filtrate solution only increases with the increase of the concentration of sodium citrate. The optimal conditions for leaching 1 mol of PbSO4 at 25℃ were found to be: 2 mol of sodium citrate solution; 2 h of reaction time and 1/3 ~ 1/5 as the starting PbSO4/water ratio. Under the experimental conditions, the conversion rate of PbSO4 was about 99% , and the remaining lead content in the filtrate solution was 3. 8% of the total lead. Pure citrate product [Pb3 ( C6H5O7)2 ] · 3H2O was crystallized from the solution, which could be decomposed to PbO/Pb powder at 350℃.

  18. Crosslinked and Dyed Chitosan Fiber Presenting Enhanced Acid Resistance and Bioactivities

    Directory of Open Access Journals (Sweden)

    Xiao-Qiong Li

    2016-04-01

    Full Text Available The application of biodegradable chitosan fiber for healthy and hygienic textiles is limited due to its poor acid resistance in wet processing and poor antioxidant activity. In order to prepare chitosan fiber with good acid resistance and high antioxidant activity, chitosan fiber was first crosslinked by a water-soluble aziridine crosslinker, and then dyed with natural lac dye consisting of polyphenolic anthraquinone compounds. The main application conditions and crosslinking mechanism of the aziridine crosslinker, the adsorption mechanism and building-up property of lac dye on the crosslinked fiber, and the effects of crosslinking and dyeing on the antioxidant and antibacterial activities of chitosan fiber were studied. The crosslinked fiber exhibited greatly reduced weight loss in acidic solution, and possessed excellent acid resistance. Lac dye displayed a very high adsorption capability on the crosslinked fiber and a high utilization rate under weakly acidic medium. The Langmuir–Nernst isotherm was the best model to describe the adsorption behavior of lac dye, and Langmuir adsorption had great contribution to total adsorption. Lac dyeing imparted good antioxidant activity to chitosan fiber. Crosslinking and dyeing had no impact on the good inherent antibacterial activity of chitosan fiber.

  19. Serial 99mTc dimercaptosuccinic acid (DMSA) scans after urinary infections presenting before the age of 5 years.

    OpenAIRE

    Verber, I G; Meller, S. T.

    1989-01-01

    Forty five children presenting with a first proven urinary tract infection under the age of 5 years were studied by sequential 99mTc dimercaptosuccinic acid (DMSA) scans. Forty nine kidneys in 40 children had definite defects at presentation, and 39 (80%) of these defects were still present when the DMSA scan was repeated. Changes in the appearance of defects were independent of the presence or degree of reflux at presentation and of symptomatic recurrence of infection, though the combination...

  20. Evaluation of field and lysimeter studies on the leaching of pesticides from soil using the PESTLA model

    NARCIS (Netherlands)

    Veen, van de J.R.; Boesten, J.J.T.I.

    1996-01-01

    The PESTLA model Version 2.4 is used to evaluate pesticide leaching from soil under Dutch agricultural conditions. A method is presented to translate the results of a leaching experiment into the standard scenario, using the ratio between measured andcomputed leaching for that experiment. An attempt

  1. Analysis of environmental impact about in-situ leaching uranium mines of Xinjiang and measures of pollution prevention

    International Nuclear Information System (INIS)

    The effects of in-situ leaching uranium on environment are analyzed from the aspects of groundwater, soil, atmosphere and surface water. Compared with conventional mining methods, in-situ leaching process has good environmental benefits, but the effect of in-situ leaching on the pollution of groundwater should not be neglected. The measures of pollution prevention are presented, and these measures can minimize the environmental pollution caused by in-situ leaching process. (authors)

  2. Adequate drainage system design for heap leaching structures.

    Science.gov (United States)

    Majdi, Abbas; Amini, Mehdi; Nasab, Saeed Karimi

    2007-08-17

    The paper describes an optimum design of a drainage system for a heap leaching structure which has positive impacts on both mine environment and mine economics. In order to properly design a drainage system the causes of an increase in the acid level of the heap which in turn produces severe problems in the hydrometallurgy processes must be evaluated. One of the most significant negative impacts induced by an increase in the acid level within a heap structure is the increase of pore acid pressure which in turn increases the potential of a heap-slide that may endanger the mine environment. In this paper, initially the thickness of gravelly drainage layer is determined via existing empirical equations. Then by assuming that the calculated thickness is constant throughout the heap structure, an approach has been proposed to calculate the required internal diameter of the slotted polyethylene pipes which are used for auxiliary drainage purposes. In order to adequately design this diameter, the pipe's cross-sectional deformation due to stepped heap structure overburden pressure is taken into account. Finally, a design of an adequate drainage system for the heap structure 2 at Sarcheshmeh copper mine is presented and the results are compared with those calculated by exiting equations. PMID:17321044

  3. Preparation, sintering and leaching of optimized uranium thorium dioxides

    Science.gov (United States)

    Hingant, N.; Clavier, N.; Dacheux, N.; Barre, N.; Hubert, S.; Obbade, S.; Taborda, F.; Abraham, F.

    2009-03-01

    Mixed actinide dioxides are currently studied as potential fuels for several concepts associated to the fourth generation of nuclear reactors. These solids are generally obtained through dry chemistry processes from powder mixtures but could present some heterogeneity in the distribution of the cations in the solid. In this context, wet chemistry methods were set up for the preparation of U1-xThxO2 solid solutions as model compounds for advanced dioxide fuels. Two chemical routes of preparation, involving the precipitation of crystallized precursor, were investigated: on the one hand, a mixture of acidic solutions containing cations and oxalic acid was introduced in an open vessel, leading to a poorly-crystallized precipitate. On the other hand, the starting mixture was placed in an acid digestion bomb then set in an oven in order to reach hydrothermal conditions. By this way, small single-crystals were obtained then characterized by several techniques including XRD and SEM. The great differences in terms of morphology and crystallization state of the samples were correlated to an important variation of the specific surface area of the oxides prepared after heating, then the microstructure of the sintered pellets prepared at high temperature. Preliminary leaching tests were finally undertaken in dynamic conditions (i.e. with high renewal of the leachate) in order to evaluate the influence of the sample morphology on the chemical durability of the final cohesive materials.

  4. 垃圾焚烧飞灰水洗-酸浸稳定化技术研究%Effects of a water-washing process on heavy metal speciation and leaching efficiency in MSWI fly ash during acid extraction

    Institute of Scientific and Technical Information of China (English)

    于昕; 薛军

    2011-01-01

    of the Pb, were found to be leached at L/S=20. The washing process resulted in more concentrated heavy metal content in the washed fly ash. A comparison of the results of acid extraction of raw ash and washed fly ash demonstra ted that increment of extracted amount of Zn improved evidently after washing, while Pb improved indistinctively. Leaching with more concentrated acid yielded greater heavy metal content from washed fly ash. The removal of most of the exchangeable and carbonate fractions from the ash, which were sensitive to the change of ion intensity and pH, was thought to be contributing to the rapid extraction of Pb and Zn as the L/S increased within 1M. The results of sequential extraction procedure reveal that the zinc and lead fractions in the extracted washed ash shifted from being mostly bound to the Fe-Mn oxides and carbonate, to being mostly bound to residual form, which is stable in the environment. Results from this work showed WWAF process can increase the environmental safety of fly ash by increasing its stability and decreasing heavy metal leachability.

  5. Leaching Properties of Naturally Occurring Heavy Metals from Soils

    Science.gov (United States)

    Zhang, M.; Hoshino, M.; Yoshikawa, M.; Hara, J.; Sugita, H.

    2014-12-01

    The major threats to human health from heavy metals are associated with exposure to arsenic, lead, cadmium, chromium, mercury, as well as some other elements. The effects of such heavy metals on human health have been extensively studied and reviewed by international organizations such as WHO. Due to their toxicity, heavy metal contaminations have been regulated by national environmental standards in many countries, and/or laws such as the Soil Contamination Countermeasures Act in Japan. Leaching of naturally occurring heavy metals from the soils, especially those around abandoned metal mines into surrounding water systems, either groundwater or surface water systems, is one of the major pathways of exposure. Therefore, understanding the leaching properties of toxic heavy metals from naturally polluted soils is of fundamentally importance for effectively managing abandoned metal mines, excavated rocks discharged from infrastructure constructions such as tunneling, and/or selecting a pertinent countermeasure against pollution when it is necessary. In this study, soil samples taken from the surroundings of abandoned metal mines in different regions in Japan were collected and analyzed. The samples contained multiple heavy metals such as lead, arsenic and chromium. Standard leaching test and sequential leaching test considering different forms of contaminants, such as trivalent and pentavalent arsenics, and trivalent and hexavalent chromiums, together with standard test for evaluating total concentration, X-ray Fluorescence Analysis (XRF), X-ray diffraction analysis (XRD) and Cation Exchange Capacity (CEC) tests were performed. In addition, sequential leaching tests were performed to evaluate long-term leaching properties of lead from representative samples. This presentation introduces the details of the above experimental study, discusses the relationships among leaching properties and chemical and mineral compositions, indicates the difficulties associated with

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

    International Nuclear Information System (INIS)

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

  7. Label-free direct surface-enhanced Raman scattering (SERS) of nucleic acids (Conference Presentation)

    Science.gov (United States)

    Guerrini, Luca; Morla-Folch, Judit; Gisbert-Quilis, Patricia; Xie, Hainan; Alvarez-Puebla, Ramon

    2016-03-01

    Recently, plasmonic-based biosensing has experienced an unprecedented level of attention, with a particular focus on the nucleic acid detection, offering efficient solutions to engineer simple, fast, highly sensitive sensing platforms while overcoming important limitations of PCR and microarray techniques. In the broad field of plasmonics, surface-enhanced Raman scattering (SERS) spectroscopy has arisen as a powerful analytical tool for detection and structural characterization of biomolecules. Today applications of SERS to nucleic acid analysis largely rely on indirect strategies, which have been demonstrated very effective for pure sensing purposes but completely dismiss the exquisite structural information provided by the direct acquisition of the biomolecular vibrational fingerprint. Contrarily, direct label-free SERS of nucleic acid shows an outstanding potential in terms of chemical-specific information which, however, remained largely unexpressed mainly because of the inherent poor spectral reproducibility and/or limited sensitivity. To address these limitations, we developed a fast and affordable high-throughput screening direct SERS method for gaining detailed genomic information on nucleic acids (DNA and RNA) and for the characterization and quantitative recognition of DNA interactions with exogenous agents. The simple strategy relies on the electrostatic adhesion of DNA/RNA onto positively-charged silver colloids that promotes the nanoparticle aggregation into stable clusters yielding intense and reproducible SERS spectra at picogram level (i.e. the analysis can be performed without the necessity of amplification steps thus providing realistic direct information of the nucleic acid in its native state). We anticipate this method to gain a vast impact and set of applications in different fields, including medical diagnostics, genomic screening, drug discovery, forensic science and even molecular electronics.

  8. Ultra fast microwave-assisted leaching for the recovery of copper and tellurium from copper anode slime

    Science.gov (United States)

    Ma, Zhi-yuan; Yang, Hong-ying; Huang, Song-tao; Lü, Yang; Xiong, Liu

    2015-06-01

    The decomposition of copper anode slime heated by microwave energy in a sulfuric acid medium was investigated. Leaching experiments were carried out in a multi-mode cavity with microwave assistance. The leaching process parameters were optimized using response surface methodology (RSM). Under the optimized conditions, the leaching efficiencies of copper and tellurium were 99.56% ± 0.16% and 98.68% ± 0.12%, respectively. Meanwhile, a conventional leaching experiment was performed in order to evaluate the influence of microwave radiation. The mechanism of microwave-assisted leaching of copper anode slime was also investigated. In the results, the microwave technology is demonstrated to have a great potential to improve the leaching efficiency and reduce the leaching time. The enhanced recoveries of copper and tellurium are believed to result from the presence of a temperature gradient due to the shallow microwave penetration depth and the superheating at the solid-liquid interface.

  9. New technology of bio-heap leaching uranium ore and its industrial application in Ganzhou uranium mine

    International Nuclear Information System (INIS)

    Bioleaching mechanism of uranium ore is discussed. Incubation and selection of new strain, biomembrane oxidizing tank--a kind of new equipment for bacteria culture and oxidation regeneration of leaching agent are also introduced. The results of industrial experiment and industrial production are summarized. Compared with conventional heap leaching, bioleaching period and acid amount are reduced, oxidant and leaching agent are saved, and uranium concentration in leaching solution is increased. It is the first time to realize industrial production by bio-heap leaching in Chinese uranium mine. New equipment-biomembrane oxidizing tank give the basis of bio-heap leaching industrial application. Bio-heap leaching process is an effective technique to reform technique of uranium mine and extract massive low-content uranium ore in China. (authors)

  10. 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...... elements, the released concentrations were very similar after 48h and 168h, indicating near-equilibrium conditions in the system. Calcite, clinopyroxenes, quartz and amorphous phases predominated in the fly ash. Various metallic sulfides, alloys and the presence of Cu, Co and Zn in silicates and glass were...... and Cu. However, there is a high risk of Co, Cu, Pb and Zn mobility in the acidic soils around the smelter facility. Therefore, potential local options for “stabilisation” of the fly ash were evaluated on the basis of the modelling results using the PHREEQC code....

  11. 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

  12. 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.

  13. Influence of Organic Amendments on Adsorption, Desorption and Leaching of Methiopyrisulfuron in Soils

    Institute of Scientific and Technical Information of China (English)

    WU Chun-xian; NIE Guo; ZHANG Zhong-ming; WANG Guang-cheng; GAO Li-ming; WANG Jin-jun

    2013-01-01

    Methiopyrisulfuron is a novel sulfonylurea herbicide with good activity for annual broadleaf and gramineal weeds control. Present study was to investigate the effects of organic amendments (including peat (PE), sewage sludge (SS), and humic acid (HA)) on adsorption, desorption and leaching of methiopyrisulfuron in soils. The batch equilibration technique was applied for adsorption-desorption experiments and the leaching was tested through soil column simulated experiments under laboratory conditions. The Freundlich model may well describe adsorption-desorption of methiopyrisulfuron on organic amendments, the natural soil, and amended soils. Organic amendments could not only greatly increase the adsorption capacity of methiopyrisulfuron, but also significantly enhance the hysteresis of desorption of methiopyrisulfuron. The correlations between Kf-ads and organic matter content of amended soils were significant, and the correlations between H and soil organic matter in amended soils with PE, SS, and HA were significant too. The results of soil column experiments indicated that organic amendments greatly decreased leaching of methiopyrisulfuron. This study suggested that PE, SS, and HA could greatly influence environmental behavior of methiopyrisulfuron in soils. Use of organic amendments might be an effective management practice for controlling potential pollution of methiopyrisulfuron to environment.

  14. Leaching of Major and Minor Elements during the Transport and Storage of Coal Ash Obtained in Power Plant

    Directory of Open Access Journals (Sweden)

    Rada Krgović

    2014-01-01

    Full Text Available In power plant, coal ash obtained by combustion is mixed with river water and transported to the dump. Sequential extraction was used in order to assess pollution caused by leaching of elements during ash transport through the pipeline and in the storage (cassettes. A total of 80 samples of filter ash as well as the ash from active (currently filled and passive (previously filled cassettes were studied. Samples were extracted with distilled water, ammonium acetate, ammonium oxalate/oxalic acid, acidic solution of hydrogen-peroxide, and a hydrochloric acid. Concentrations of the several elements (Al, As, Cd, Co, Cu, Cr, Fe, Ba, Ca, Mg, Ni, Pb, and Zn in all extracts were determined by inductively coupled plasma atomic emission spectrometry. Pattern recognition method was carried out in order to provide better understanding of the nature of distribution of elements according to their origins. Results indicate possible leaching of As, Ca, Cd, Cu, Zn, and Pb. Among these elements As, Cd, and Pb are toxicologically the most important but they were not present in the first two phases with the exception of As. The leaching could be destructive and cause negative effects on plants, water pollution, and damage to some life forms.

  15. The roasting and leaching of Witwatersrand pyrite concentrates

    International Nuclear Information System (INIS)

    Many of the pyrite concentrates produced at South African gold and uranium mines contain economically significant amounts of nickel, copper, and cobalt, apart from gold and uranium. The extent to which base metals, particularly cyanocides in the calcine, can be made soluble in water or in dilute acid by variation of the pyrite roasting conditions was investigated. An important finding of the investigation was that the conditions producing favourable base-metal sulphation (and hence solubility in water) also produced good sulphation of the uranium values that had not been extracted in a conventional leach of the original pyrite. Thus, if the pyrite is subjected to a sulphating roast followed by quenching in water (or dilute acid), it should be possible for the uranium to be extracted in improved yield. The need for leaching of the pyrite would therefore fall away. It was noted that sulphation roasting also resulted in improved gold extractions when the calcine was subsequently subjected to conventional cyanide-extraction procedures. From well-sulphated calcine, the dissolution of base metals and uranium appeared to be fairly independent of leaching pH, time, and temperature. On an inadequately sulphated calcine, low pH values during leaching gave increased extraction of copper and uranium but did not have a significant effect on the dissolution of nickel and cobalt. The extraction of uranium increased with increasing leaching time and temperature, while only longer times at a low pH value markedly improved the extraction of copper. The extraction of cobalt was fairly independent of leaching time and temperature, but the results were insufficient for a conclusive evaluation to be made of their effects on the dissolution of nickel. A cursory economic assessment indicated that sulphation roasting applied to the pyrite investigated is likely to be very profitable

  16. Leaching characteristics of Wadi Belih uraniferous Hammamat sediments,eastern desert,Egypt

    International Nuclear Information System (INIS)

    This work deals with the direct chemical treatment of Wadi Belih uraniferous ore material using the agitation leaching technique. The study ore is mainly localized in siltstones belonging to the Hammamat sediments situated in the northern part of the eastern desert. The uranium mineral in the ore are mainly represented by the silicate mineral uranophane, the vanadate mineral tyuyamunite and to a laser extent the sulphate mineral shroekingerite, both acid (sulphuric acid) alkaline (sodium carbonate and bicarbonate) leaching methods have been applied beside sodium and ferric chlorides. The latter leaching reagents are greatly beneficial in removing radium together with uranium, a matter which is greatly important for environmental concerns

  17. Triterpenic Acids Present in Hawthorn Lower Plasma Cholesterol by Inhibiting Intestinal ACAT Activity in Hamsters

    Directory of Open Access Journals (Sweden)

    Yuguang Lin

    2011-01-01

    Full Text Available Hawthorn (Crataegus pinnatifida is an edible fruit used in traditional Chinese medicine to lower plasma lipids. This study explored lipid-lowering compounds and underlying mechanisms of action of hawthorn. Hawthorn powder extracts inhibited acylCoA:cholesterol acyltransferase (ACAT activity in Caco-2 cells. The inhibitory activity was positively associated with triterpenic acid (i.e., oleanolic acid (OA and ursolic acid (UA contents in the extracts. Cholesterol lowering effects of hawthorn and its potential additive effect in combination with plant sterol esters (PSE were further studied in hamsters. Animals were fed a semi-synthetic diet containing 0.08% (w/w cholesterol (control or the same diet supplemented with (i 0.37% hawthorn dichloromethane extract, (ii 0.24% PSE, (iii hawthorn dichloromethane extract (0.37% plus PSE (0.24% or (iv OA/UA mixture (0.01% for 4 weeks. Compared to the control diet, hawthorn, PSE, hawthorn plus PSE and OA/UA significantly lowered plasma non-HDL (VLDL + LDL cholesterol concentrations by 8%, 9%, 21% and 6% and decreased hepatic cholesterol ester content by 9%, 23%, 46% and 22%, respectively. The cholesterol lowering effects of these ingredients were conversely associated with their capacities in increasing fecal neutral sterol excretion. In conclusion, OA and UA are responsible for the cholesterol lowering effect of hawthorn by inhibiting intestinal ACAT activity. In addition, hawthorn and particularly its bioactive compounds (OA and UA enhanced the cholesterol lowering effect of plant sterols.

  18. Impact of Roasting on Fatty Acids, Tocopherols, Phytosterols, and Phenolic Compounds Present in Plukenetia huayllabambana Seed

    Directory of Open Access Journals (Sweden)

    Rosana Chirinos

    2016-01-01

    Full Text Available The effect of roasting of Plukenetia huayllabambana seeds on the fatty acids, tocopherols, phytosterols, and phenolic compounds was evaluated. Additionally, the oxidative stability of the seed during roasting was evaluated through free fatty acids, peroxide, and p-anisidine values in the seed oil. Roasting conditions corresponded to 100, 120, 140, and 160°C for 10, 20, and 30 min, respectively. Results indicate that roasting temperatures higher than 120°C significantly affect the content of the studied components. The values of acidity, peroxide, and p-anisidine in the sacha inchi oil from roasted seeds increased during roasting. The treatment of 100°C for 10 min successfully maintained the evaluated bioactive compounds in the seed and quality of the oil, while guaranteeing a higher extraction yield. Our results indicate that P. huayllabambana seed should be roasted at temperatures not higher than 100°C for 10 min to obtain snacks with high levels of bioactive compounds and with high oxidative stability.

  19. RepSeq – A database of amino acid repeats present in lower eukaryotic pathogens

    Directory of Open Access Journals (Sweden)

    Smith Deborah F

    2007-04-01

    Full Text Available Abstract Background Amino acid repeat-containing proteins have a broad range of functions and their identification is of relevance to many experimental biologists. In human-infective protozoan parasites (such as the Kinetoplastid and Plasmodium species, they are implicated in immune evasion and have been shown to influence virulence and pathogenicity. RepSeq http://repseq.gugbe.com is a new database of amino acid repeat-containing proteins found in lower eukaryotic pathogens. The RepSeq database is accessed via a web-based application which also provides links to related online tools and databases for further analyses. Results The RepSeq algorithm typically identifies more than 98% of repeat-containing proteins and is capable of identifying both perfect and mismatch repeats. The proportion of proteins that contain repeat elements varies greatly between different families and even species (3–35% of the total protein content. The most common motif type is the Sequence Repeat Region (SRR – a repeated motif containing multiple different amino acid types. Proteins containing Single Amino Acid Repeats (SAARs and Di-Peptide Repeats (DPRs typically account for 0.5–1.0% of the total protein number. Notable exceptions are P. falciparum and D. discoideum, in which 33.67% and 34.28% respectively of the predicted proteomes consist of repeat-containing proteins. These numbers are due to large insertions of low complexity single and multi-codon repeat regions. Conclusion The RepSeq database provides a repository for repeat-containing proteins found in parasitic protozoa. The database allows for both individual and cross-species proteome analyses and also allows users to upload sequences of interest for analysis by the RepSeq algorithm. Identification of repeat-containing proteins provides researchers with a defined subset of proteins which can be analysed by expression profiling and functional characterisation, thereby facilitating study of pathogenicity

  20. Hypochlorous acid-mediated oxidation of lipid components and antioxidants present in low-density lipoproteins

    DEFF Research Database (Denmark)

    Pattison, David I; Hawkins, Clare L; Davies, Michael Jonathan

    2003-01-01

    Oxidation of low-density lipoproteins (LDL) is believed to contribute to the increased uptake of LDL by macrophages, which is an early event in atherosclerosis. Hypochlorous acid (HOCl) has been implicated as one of the major oxidants involved in these processes. In a previous study, the rates...... are relatively ineffective as direct scavengers for HOCl as compared to water soluble antioxidants (e.g., ascorbate, k ca. 10(6) M(-)(1) s(-)(1)). The reaction of HOCl with hydroquinone (a simple model for ubiquinol-10) was also investigated both in aqueous solution (k = 45 M(-)(1) s(-)(1)) and in a less polar...

  1. Lead, Cadmium and Cobalt (Pb, Cd, and Co Leaching of Glass-Clay Containers by pH Effect of Food

    Directory of Open Access Journals (Sweden)

    Juan Diego García-Paredes

    2011-04-01

    Full Text Available Recent studies have shown that handcrafted glass-clay containers are a health risk because they can be contaminated by heavy metals, which can be transferred to food, thus reaching the human body to potentially cause illness. Therefore, in the present work, we evaluate the leaching of lead, cadmium, and cobalt from glass-clay containers into two types of food: tomato sauce (salsa, and chickpea puree. The containers were obtained from four regions in the Mexican state of Hidalgo. Repetitive extractions from the containers were carried out to quantify the leaching of the heavy metals into the salsa, the chickpea puree, and acetic acid using the technique proposed by the USFDA. The results show that greater use of the containers leads to more leaching of heavy metals into both types of food and into the acetic acid, with the greatest metal extraction recorded for the Ixmiquilpan vessels. These results indicate that the metals present in the glass-clay containers leach into the food and that increased reuse increases the risk to the people who use them in food preparation.

  2. A preferential flow leaching index

    NARCIS (Netherlands)

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

    2009-01-01

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

  3. 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.

  4. Acid rain monitoring in East-Central Florida from 1977 to present

    Science.gov (United States)

    Madsen, B. C.; Kheoh, T.; Hinkle, C. R.; Dreschel, T. W.

    1990-01-01

    Rainfall has been collected on the University of Central Florida campus and at the Kennedy Space Center over a 12 year period. The chemical composition has been determined and summarized by monthly, annual periods, and for the entire 12 year period at both locations. The weighted average pH at each site is 4.58; however, annual weighted average pH has been equal to or above the 12 year average during six of the past eight years. Nitrate concentrations have increased slightly during recent years while excess sulfate concentrations have remained below the 12 year weighted average during six of the past seven years. Stepwise regression suggests that sulfate, nitrate, ammonium ion and calcium play major roles in the description of rainwater acidity. Annual acid deposition and annual rainfall have varied from 20 to 50 meg/(m(exp 2) year) and 100 to 180 cm/year, respectively. Sea salt comprises at least 25 percent of the total ionic composition.

  5. Simultaneous analysis of saturated and unsaturated fatty acids present in pequi fruits by capillary electrophoresis

    Directory of Open Access Journals (Sweden)

    Patrícia M. de Castro Barra

    2013-01-01

    Full Text Available In the current study, an alternative method has been proposed for simultaneous analysis of palmitic, stearic, oleic, linoleic, and linolenic acids by capillary zone electrophoresis (CZE using indirect detection. The background electrolyte (BGE used for the analysis of these fatty acids (FAs consisted of 15.0 mmol L−1 NaH2PO4/Na2HPO4 at pH 6.86, 4.0 mmol L−1 SDBS, 8.3 mmol L−1 Brij 35, 45% v/v acetonitrile (can, and 2.1% n-octanol. The FAs quantification of FAs was performed using a response factor approach, which provided a high analytical throughput for the real sample. The CZE method, which was applied successfully for the analysis of pequi pulp, has advantages such as short analysis time, absence of lipid fraction extraction and derivatization steps, and no significant difference in the 95% confidence intervals for FA quantification results, compared to the gas chromatography official method (AOCS Ce 1h-05.

  6. Behaviour of the pH adjustment, Ion exchange and concentrate precipitation stages in the acid leaching of uranium phosphate ores; Tratamiento de disoluciones de lixiviacion de minerales de uranio en presencia de fosfatos. Comportamiento en las etapas de ajuste de PH, cambio de ion y precipitacion de concentrados

    Energy Technology Data Exchange (ETDEWEB)

    Estrada Aguilar, J.; Uriarte Hueda, A.

    1962-07-01

    The uranium recovery from acid leach solutions of uranium-phosphate ores has been studied. Relations have been found between the solution characteristics and the results obtained at different stages of the process. The following data can thus be predicted: solids to remove and uranium recovery in the pH adjustment stage, uranium capacity of the resin, more suitable eluating agent, elution velocity and uranium concentration in the eluate in the ion exchange stage, and composition of the concentrate produced by direct precipitation of the eluate in the concentrate precipitation stage. (Author) 8 refs.

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

    International Nuclear Information System (INIS)

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

  8. Gold leaching with elemental sulfur in alkaline solutions under oxygen pressure

    Institute of Scientific and Technical Information of China (English)

    方兆珩; 石伟

    2003-01-01

    A gold leaching process by using oxidation products of elemental sulfur in alkaline solutions was pro-posed and investigated. A gold concentrate and a residue from an arsenic refractory gold concentrate by acidic oxida-tion leaching were tested. The residue contains 16.3% elemental sulfur and no more elemental sulfur was added intests. For the concentrate elemental sulfur was added before leaching tests. The leaching ratio of gold depends main-ly on the initial equivalent ratio of elemental sulfur to hydroxyl ions, the consumption of oxygen and the reactiontemperature in the process. Analysis of the experimental results shows that thiosulfate is the majority complexingreagent for gold in the process. Over 90% gold was leached from the residue and 82%-87% from the concentrate byusing this process.

  9. 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...... percolation experiments; liquid-to-solid (L/S) ratios of 200-250 L/kg corresponding to more than 10,000 years in a conventional landfill were reached. Less than 2% of the initially present As, Cu, Pb, Zn, Cr, and Sb had leached during the Course of the experiments. Concentrations of Cd, Fe, Mg, Hg, Mn, Ni, Co...

  10. Solid waste and leaching studies using nuclear analytical techniques

    International Nuclear Information System (INIS)

    As a result of the awareness of the potential hazards that solid wastes may pose to the environment, many countries have instituted research agendas and regulations to address these issues issues. During the past fifteen years there has been a plethora of leaching studies proposed to ascertain the potential impact that solid wastes may have on water quality. Regulatory laboratory leaching procedures should be applicable to a variety of waste types while providing useful data for the prediction of leachate quality generated by the wastes in a landfill environment. Although it is unrealistic to expect a single laboratory leaching procedure to reliably assess all wastes, an ideal procedure would include the following features: (a) use a leaching medium to be encountered in a landfill (b) include procedures to estimate the intensity and dynamics of Teachable constituents; (c) minimize sample particle size alteration; (d) optimize the liquid to solid ratio to minimize leachate dilution and experimental variability; (e) avoid exotic laboratory apparatus; and (f) restrict procedures used to those conveniently performed by laboratory personnel. In the University of Illinois laboratories, the focus is on assessing the short and long term hazards from municipal solid waste, incinerator ash and coal fly ash through the elemental analysis of heavy metals in ash and leachates using a variety of multi-elemental techniques. Other studies have included the identification of heavy metals in household plastics and the characterization of contaminated soils in urban environments. These techniques included neutron activation analysis, X ray fluorescence spectrometry and inductively coupled plasma-atomic emission spectrometry. The leaching tests have included the Toxicity Characteristic Leaching Procedure, water batch extraction, sequential extraction and column tests. The philosophy of leaching procedures, the strength of non-destructive multi-elemental techniques, and results from

  11. 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.

  12. Influence of acidified acidity to uranium bioleaching

    International Nuclear Information System (INIS)

    The relationship between the acidified acidity and the acid consumption and uranium leaching rate in the process of uranium bioleaching is investigated. Results indicate that higher uranium leaching rate is obtained when the relatively high acidity was applied at beginning. For different minerals, although the original acidity should be different, lower original acidity was not better for shortening leaching period and improving uranium leaching rate. It confirms 30-40 g/L sulfuric acid as the original acidity was more suitable and more than 30 g/ L should be applied if the mineral particle sizes were larger. (authors)

  13. Retinoic acid-treated pluripotent stem cells undergoing neurogenesis present increased aneuploidy and micronuclei formation.

    Directory of Open Access Journals (Sweden)

    Rafaela C Sartore

    Full Text Available The existence of loss and gain of chromosomes, known as aneuploidy, has been previously described within the central nervous system. During development, at least one-third of neural progenitor cells (NPCs are aneuploid. Notably, aneuploid NPCs may survive and functionally integrate into the mature neural circuitry. Given the unanswered significance of this phenomenon, we tested the hypothesis that neural differentiation induced by all-trans retinoic acid (RA in pluripotent stem cells is accompanied by increased levels of aneuploidy, as previously described for cortical NPCs in vivo. In this work we used embryonal carcinoma (EC cells, embryonic stem (ES cells and induced pluripotent stem (iPS cells undergoing differentiation into NPCs. Ploidy analysis revealed a 2-fold increase in the rate of aneuploidy, with the prevalence of chromosome loss in RA primed stem cells when compared to naïve cells. In an attempt to understand the basis of neurogenic aneuploidy, micronuclei formation and survivin expression was assessed in pluripotent stem cells exposed to RA. RA increased micronuclei occurrence by almost 2-fold while decreased survivin expression by 50%, indicating possible mechanisms by which stem cells lose their chromosomes during neural differentiation. DNA fragmentation analysis demonstrated no increase in apoptosis on embryoid bodies treated with RA, indicating that cell death is not the mandatory fate of aneuploid NPCs derived from pluripotent cells. In order to exclude that the increase in aneuploidy was a spurious consequence of RA treatment, not related to neurogenesis, mouse embryonic fibroblasts were treated with RA under the same conditions and no alterations in chromosome gain or loss were observed. These findings indicate a correlation amongst neural differentiation, aneuploidy, micronuclei formation and survivin downregulation in pluripotent stem cells exposed to RA, providing evidence that somatically generated chromosomal

  14. Evaluation of leaching potential of three systemic neonicotinoid insecticides in vineyard soil

    Science.gov (United States)

    Kurwadkar, Sudarshan; Wheat, Remington; McGahan, Donald G.; Mitchell, Forrest

    2014-12-01

    Dinotefuran (DNT), imidacloprid (IMD), and thiamethoxam (THM) are commonly used neonicotinoid insecticides in a variety of agriculture operations. Although these insecticides help growers control pest infestation, the residual environmental occurrence of insecticides may cause unintended adverse ecological consequences to non-target species. In this study, the leaching behavior of DNT, IMD, and THM was investigated in soils collected from an active AgriLife Research Extension Center (AREC) vineyard. A series of column experiments were conducted to evaluate the leaching potential of insecticides under two experimental scenarios: a) individual pulse mode, and b) mixed pulse mode. In both scenarios, the breakthrough pattern of the insecticides in the mostly acidic to neutral vineyard soil clearly demonstrates medium to high leachability. Of the three insecticides studied for leaching, DNT has exhibited high leaching potential and exited the column with fewer pore volumes, whereas IMD was retained for longer, indicating lower leachability. Relative differences in leaching behavior of neonicotinoids could be attributed to their solubility with the leaching pattern IMD insecticides. The repeatability of the breakthrough curves shows that both DNT and IMD are reproducible between runs, whereas, THM shows some inconsistency. Leaching behavior of neonicotinoid insecticides based on the leachability indices such as groundwater ubiquity score, relative leaching potential, and partitioning between different environmental matrices through a fugacity-based equilibrium criterion model clearly indicates that DNT may pose a greater threat to aquatic resources compared to IMD and THM.

  15. Dissolved carbon leaching from soil is a crucial component of the net ecosystem carbon balance

    DEFF Research Database (Denmark)

    Kindler, Reimo; Siemens, Jan; Kaiser, Klaus;

    2011-01-01

    Estimates of carbon leaching losses from different land use systems are few and their contribution to the net ecosystem carbon balance is uncertain. We investigated leaching of dissolved organic carbon (DOC), dissolved inorganic carbon (DIC), and dissolved methane (CH4), at forests, grasslands, a...... solubility of CO2 in acidic forest soil solutions and large NEE. Leaching of CH4 proved to be insignificant compared with other fluxes of carbon. Overall, our results show that leaching losses are particularly important for the carbon balance of agricultural systems.......Estimates of carbon leaching losses from different land use systems are few and their contribution to the net ecosystem carbon balance is uncertain. We investigated leaching of dissolved organic carbon (DOC), dissolved inorganic carbon (DIC), and dissolved methane (CH4), at forests, grasslands...... ecosystem exchange (NEE) plus carbon inputs with fertilization minus carbon removal with harvest. Carbon leaching increased the net losses from cropland soils by 24–105% (median: 25%). For the majority of forest sites, leaching hardly affected actual net ecosystem carbon balances because of the small...

  16. Pretreatment and thiosulfate leaching of refractory gold-bearing arsenosulfide concentrates

    Institute of Scientific and Technical Information of China (English)

    Yuqun Meng

    2005-01-01

    A hydrometallurgical process for refractory gold-bearing arsenosulfide concentrates at ambient temperature and pressure was presented, including fine grinding with intensified alkali-leaching (FGIAL), enhanced agitation alkali-leaching (EAAL), thiosulfate leaching and displacement. Experimental results on a refractory gold concentrate showed that the total consumption of NaOH in alkaline leaching is only 41% of those theoretically calculated under the conditions of full oxidization for the same amount of arsenides and sulfides transformed into arsenates and sulfates, and 72.3% of gold is synchro-dissoluted by thiosulfate self-generated during alkaline leaching. After alkaline leaching, thiosulfate leaching was carried out for 24 h. The dissolution of gold is increased to 91.9% from 4.6% by cyanide without the pretreatment. The displacement of gold by zinc powder in the solution gets to 99.2%. Due to an amount of thiosulfate self-generated during alkaline leaching, the reagent addition in thiosulfate leaching afterwards is lower than the normal.

  17. Cadmium telluride leaching behavior: Discussion of Zeng et al. (2015).

    Science.gov (United States)

    Sinha, Parikhit

    2015-11-01

    Zeng et al. (2015) evaluate the leaching behavior and surface chemistry of II-VI semiconductor materials, CdTe and CdSe, in response to pH and O2. Under agitation in acidic and aerobic conditions, the authors found approximately 3.6%-6.4% (w/w) solubility of Cd content in CdTe in the Toxicity Characteristic Leaching Procedure (TCLP), Waste Extraction Test (WET), and dissolution test, with lower solubility (0.56-0.58%) under agitation in acidic and anoxic conditions. This range is comparable with prior long-term transformation and dissolution testing and bio-elution testing of CdTe (2.3%-4.1% w/w solubility of Cd content in CdTe). The implications for potential leaching behavior of CdTe-containing devices require further data. Since CdTe PV modules contain approximately 0.05% Cd content by mass, the starting Cd content in the evaluation of CdTe-containing devices would be lower by three orders of magnitude than the starting Cd content in the authors' study, and leaching potential would be further limited by the monolithic glass-adhesive laminate-glass structure of the device that encapsulates the semiconductor material. Experimental evaluation of leaching potential of CdTe PV modules crushed by landfill compactor has been conducted, with results of TCLP and WET tests on the crushed material below regulatory limits for Cd. CdTe PV recycling technology has been in commercial operation since 2005 with high yields for semiconductor (95%) and glass (90%) recovery. PMID:26320011

  18. In situ leaching of uranium: Technical, environmental and economic aspects

    International Nuclear Information System (INIS)

    Within the framework of its activities in nuclear raw materials the International Atomic Energy Agency has convened a series of meetings to discuss various aspects of uranium ore processing technology, recovery of uranium from non-conventional resources and development of projects for the production of uranium concentrates including economic aspects. As part of this continuing effort to discuss and document important aspects of uranium production the IAEA convened a Technical Committee Meeting on Technical, Economic and Environmental Aspects of In-Situ Leaching. Although the use of this technique is limited by geological and economic constraints, it has a significant potential to produce uranium at competitive prices. This is especially important in the current uranium market which is mainly characterised by large inventories, excess production capability and low prices. This situation is not expected to last indefinitely but it is unlikely to change drastically in the next ten years or so. This Technical Committee Meeting was held in Vienna from 3 to 6 November 1987 with the attendance of 24 participants from 12 countries. Eight papers were presented. Technical sessions covered in-situ mining research, environmental and licensing aspects and restoration of leached orebodies; the technological status of in-situ leaching, the current status and future prospects of in-situ leaching of uranium in Member States, general aspects of planning and implementation of in-situ projects and the economics of in-situ leaching. Refs, figs and tabs

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

    Energy Technology Data Exchange (ETDEWEB)

    Rudeen, David Keith [GRAM, Inc., Albuquerque, NM; 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. Aluminium leaching from red mud by filamentous fungi.

    Science.gov (United States)

    Urík, Martin; Bujdoš, Marek; Milová-Žiaková, Barbora; Mikušová, Petra; Slovák, Marek; Matúš, Peter

    2015-11-01

    This contribution investigates the efficient and environmentally friendly aluminium leaching from red mud (bauxite residue) by 17 species of filamentous fungi. Bioleaching experiments were examined in batch cultures with the red mud in static, 7-day cultivation. The most efficient fungal strains in aluminium bioleaching were Penicillium crustosum G-140 and Aspergillus niger G-10. The A. niger G-10 strain was capable to extract up to approximately 141 mg·L(-1) of aluminium from 0.2 g dry weight red mud. Chemical leaching with organic acids mixture, prepared according to A. niger G-10 strain's respective fungal excretion during cultivation, proved that organic acids significantly contribute to aluminium solubilization from red mud.

  1. Aluminium leaching from red mud by filamentous fungi.

    Science.gov (United States)

    Urík, Martin; Bujdoš, Marek; Milová-Žiaková, Barbora; Mikušová, Petra; Slovák, Marek; Matúš, Peter

    2015-11-01

    This contribution investigates the efficient and environmentally friendly aluminium leaching from red mud (bauxite residue) by 17 species of filamentous fungi. Bioleaching experiments were examined in batch cultures with the red mud in static, 7-day cultivation. The most efficient fungal strains in aluminium bioleaching were Penicillium crustosum G-140 and Aspergillus niger G-10. The A. niger G-10 strain was capable to extract up to approximately 141 mg·L(-1) of aluminium from 0.2 g dry weight red mud. Chemical leaching with organic acids mixture, prepared according to A. niger G-10 strain's respective fungal excretion during cultivation, proved that organic acids significantly contribute to aluminium solubilization from red mud. PMID:26365318

  2. Multiphase simulation of mine waters and aqueous leaching processes

    Directory of Open Access Journals (Sweden)

    Pajarre Risto

    2016-01-01

    Full Text Available Managing of large amounts of water in mining and mineral processing sites remains a concern in both actively operated and closed mining areas. When the mining site with its metal or concentrate producing units is operational, the challenge is to find either ways for economical processing with maximum yields, while minimizing the environmental impact of the water usage and waste salt treatments. For safe closure of the site, the environmental control of possible drainage will be needed. For both challenges, the present-day multiphase process simulations tools can be used to provide improved accuracy and better economy in controlling the smooth and environmentally sound operation of the plant. One of the pioneering studies in using the multiphase thermodynamic software in simulation of hydrometallurgical processes was that of Koukkari et al. [1]. The study covered the use of Solgasmix equilibrium software for a number of practical acid digesters. The models were made for sulfuric acid treatments in titania pigment production and in NPK fertilizer manufacturing. During the past two decades the extensive data assessment has taken place particularly in geochemistry and a new versions of geochemical multiphase equilibrium software has been developed. On the other hand, there has been some progress in development of the process simulation software in all the aforementioned fields. Thus, the thermodynamic simulation has become a tool of great importance in development of hydrometallurgical processes. The presentation will cover three example cases of either true pilot or industrial systems including a South African acid mine water drainage treatment, hydrometallurgical extraction of rare earths from uranium leachate in Russia and a multistage process simulation of a Finnish heap leaching mine with its subsequent water treatment system.

  3. Leaching of zinc from rubber infill on artificial turf (football pitches)

    NARCIS (Netherlands)

    Verschoor AJ; LER

    2007-01-01

    Many artificial football pitches are treated with a rubber infill made of recycled tyres. From this material zinc leaches to the soil, groundwater and surface water. [This can present significant environmental risks, particularly for aquatic life.] Human health risks posed by leaching of zinc are ne

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

    OpenAIRE

    Yao J.H.; Li X.H.; Li Y.W.

    2011-01-01

    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...

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

    OpenAIRE

    Gargul K.; Jarosz P.; Małecki S.

    2016-01-01

    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 in...

  6. 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.

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

    OpenAIRE

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

    1999-01-01

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

  8. Heavy Metals in a Sulfidic Minespoil: Fractions and Column Leaching

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    Fractions of various heavy metals in a sulfidic minespoil were investigated. Column leaching experimentwas also conducted to simulate "acid mine drainage" (AMD) from the minespoil. The results show thatleaching of heavy metals from the minespoil was extremely significant during the initial water flushing.The amounts of heavy metals leached out dramatically reduced after leaching twice. It is worthwhile tonote that in this study, Zn, Mn, Fe, As and Ni in the first leachate exceeded the total amount of eachcorresponding water-extractable (1:5, soil:water) metal contained in the minespoil sample. This appears tosuggest that 1:5 water extraction did not allow accurate estimation of water-leachable concentrations of theabove heavy metals. This work has implications for the management of sulfidic minespoils. Acid drainageof great environmental concerns is likely to occur only during heavy rainfall events after substantial solubleand readily exchangeable acid and metals are accumulated in the minespoils. The slow-reacting fractionsother than water-soluble and readily exchangeable fractions may pose little environmental hazards. This isparticularly true for Pb, As and Ni.

  9. 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.

  10. Phosphorus leaching from clay soils can be counteracted by structure liming

    OpenAIRE

    Ulen, Barbro; Etana, Ararso

    2014-01-01

    Two field experiments with drained plots on clay soils (60 and 25 % clay) demonstrated a significant reduction in leaching of total phosphorus after application of structure lime. Aggregate stability, was significantly improved. Phosphorus leaching in particulate form was significantly reduced following structure liming at the site with a very high clay content. Sites representing low (50 mg kg-1) and high (140 mg kg-1) levels of phosphorus extractable with acid ammonium lactate in topsoil di...

  11. Microbial leaching of toxic metals and arsenic from a heap consisting of heavily polluted soil

    Science.gov (United States)

    Groudev, Stoyan; Georgiev, Plamen; Spasova, Irena; Nicolova, Marina

    2014-05-01

    Soil heavily polluted with toxic heavy metals (mainly Cu, Zn, Cd) and arsenic was subjected to microbial cleanup in a heap specially constructed for this purpose. The heap was located on an impermeable geomembrane, had the shape of a truncated pyramid and contained about 240 tons of soil collected mainly from the horizon A. The soil was highly acidic (with an initial pH of about 3.2) and was preliminarily crushed to minus 2.5 cm particle size. The pollutants were present mainly as the relevant sulphide minerals and the soil was inhabited by different microorganisms, including some acidophilic chemolithotrophic bacteria able to oxidize sulphides and to solubilize the relevant toxic elements. The heap possessed systems for irrigation and aeration and was surrounded by ditches to collect the drainage heap effluents containing the dissolved pollutants. The treatment of the soil was carried out by means of interrupted irrigation with leach solutions containing diluted sulphuric acid (to maintain pH in the heap within the range of about 2.5 - 2.8) and ammonium and phosphate ions to maintain the microbial growth. The treatment was carried out for a period of about two years during different climatic seasons. After the end of leaching the soil was subjected to some conventional melioration procedures such as liming, grassing, moulching, addition of fertilizers and animal manure and periodic ploughing and irrigation to increase its quality to levels suitable for agricultural utilization.

  12. The removal of mercury from solid mixed waste using chemical leaching processes

    International Nuclear Information System (INIS)

    The focus of this research was to evaluate chemical leaching as a technique to treat soils, sediments, and glass contaminated with either elemental mercury or a combination of several mercury species. Potassium iodide/iodine solutions were investigated as chemical leaching agents for contaminated soils and sediments. Clean, synthetic soil material and surrogate storm sewer sediments contaminated with mercury were treated with KI/I2 solutions. It was observed that these leaching solutions could reduce the mercury concentration in soil and sediments by 99.8%. Evaluation of selected posttreatment sediment samples revealed that leachable mercury levels in the treated solids exceeded RCRA requirements. The results of these studies suggest that KI/I2 leaching is a treatment process that can be used to remove large quantities of mercury from contaminated soils and sediments and may be the only treatment required if treatment goals are established on Hg residual concentrations in solid matrices. Fluorescent bulbs were used to simulate mercury contaminated glass mixed waste. To achieve mercury contamination levels similar to those found in larger bulbs such as those used in DOE facilities a small amount of Hg was added to the crushed bulbs. The most effective agents for leaching mercury from the crushed fluorescent bulbs were KI/I2, NaOCl, and NaBr + acid. Radionuclide surrogates were added to both the EPA synthetic soil material and the crushed fluorescent bulbs to determine the fate of radionuclides following chemical leaching with the leaching agents determined to be the most promising. These experiments revealed that although over 98% of the dosed mercury solubilized and was found in the leaching solution, no Cerium was measured in the posttreatment leaching solution. This finding suggest that Uranium, for which Ce was used as a surrogate, would not solubilize during leaching of mercury contaminated soil or glass

  13. Caustic Leaching of Hanford Tank S-110 Sludge

    Energy Technology Data Exchange (ETDEWEB)

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

    2001-10-31

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

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

    Institute of Scientific and Technical Information of China (English)

    梁铎强; 王吉坤; 周廷熙; 张怀伟

    2009-01-01

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

  15. Underground leaching of uranium ores

    International Nuclear Information System (INIS)

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

  16. Use of Phosphate Solubilizing Bacteria to Leach Rare Earth Elements from Monazite-Bearing Ore

    Directory of Open Access Journals (Sweden)

    Doyun Shin

    2015-04-01

    Full Text Available In the present study, the feasibility to use phosphate solubilizing bacteria (PSB to develop a biological leaching process of rare earth elements (REE from monazite-bearing ore was determined. To predict the REE leaching capacity of bacteria, the phosphate solubilizing abilities of 10 species of PSB were determined by halo zone formation on Reyes minimal agar media supplemented with bromo cresol green together with a phosphate solubilization test in Reyes minimal liquid media as the screening studies. Calcium phosphate was used as a model mineral phosphate. Among the test PSB strains, Pseudomonas fluorescens, P. putida, P. rhizosphaerae, Mesorhizobium ciceri, Bacillus megaterium, and Acetobacter aceti formed halo zones, with the zone of A. aceti being the widest. In the phosphate solubilization test in liquid media, Azospirillum lipoferum, P. rhizosphaerae, B. megaterium, and A. aceti caused the leaching of 6.4%, 6.9%, 7.5%, and 32.5% of calcium, respectively. When PSB were used to leach REE from monazite-bearing ore, ~5.7 mg/L of cerium (0.13% of leaching efficiency and ~2.8 mg/L of lanthanum (0.11% were leached by A. aceti, and Azospirillum brasilense, A. lipoferum, P. rhizosphaerae and M. ciceri leached 0.5–1 mg/L of both cerium and lanthanum (0.005%–0.01%, as measured by concentrations in the leaching liquor. These results indicate that determination of halo zone formation was found as a useful method to select high-capacity bacteria in REE leaching. However, as the leaching efficiency determined in our experiments was low, even in the presence of A. aceti, further studies are now underway to enhance leaching efficiency by selecting other microorganisms based on halo zone formation.

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

    Science.gov (United States)

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

    2015-08-15

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

  18. Production of fermented probiotic beverages from milk permeate enriched with whey retentate and identification of present lactic acid bacteria

    Directory of Open Access Journals (Sweden)

    Jagoda Šušković

    2009-03-01

    Full Text Available In this research the application of bacterial strains Lactobacillus acidophilus M92, Lactobacillus plantarum L4 and Enterococcus faecium L3 in the production of fermented probiotic beverages from milk permeate enriched with 10 % (v/v whey retentate, was investigated. In the previous researches of probiotic concept, probiotic properties of these three strains of lactic acid bacteria have been defined. At the end of controlled fermentation, probiotic strains have produced 7.4 g/L lactic acid, pH was decreased to 4.7, and number of live cells was around 108 CFU/mL. Number of viable count of probiotic bacteria, which were identified with RAPD (Random Amplified Polymorphic DNAmethod, was maintained at around 107 CFU/mL during 28 days of the preservation at 4 °C. Furthermore, a spontaneous fermentation of milk permeate enriched with 10 % (v/v of whey retentate was carried out and lactic acid bacteria present in these substrates were isolated. All of these bacterial strains have rapidly acidified the growth media and have shown antibacterial activity against chosen test-microorganisms, what are important properties of potential starter cultures for the fermentation of dairy products. The results of biochemical API analysis have identified isolated strains as Lactococcus lactis subsp. lactis and Lactobacillus helveticus.

  19. 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.

  20. Saltstone Oxidation Study: Leaching Method

    Energy Technology Data Exchange (ETDEWEB)

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

    2013-02-24

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

  1. Intensification of pretreatment and pressure leaching of copper anode slime by microwave radiation

    Institute of Scientific and Technical Information of China (English)

    杨洪英; 马致远; 黄松涛; 吕阳; 熊柳

    2015-01-01

    The application of microwave irradiation for pretreatment of copper anode slime with high nickel content prior to pressure sulfuric acid leaching has been proposed. The microwave-assisted pretreatment is a rapid and efficient process. Through the technology of microwave assisted pretreatment-pressure leaching of copper anode slime, copper, tellurium, selenium and nickel are almost completely recovered. Under optimal conditions, the leaching efficiencies of copper, tellurium, selenium and nickel are 97.12%, 95.97%, 95.37% and 93.90%, respectively. The effect of microwave radiation on the temperature of copper anode slime and leaching solution is investigated. It is suggested that the enhancement on the recoveries of copper, tellurium and selenium can be attributed to the temperature gradient which is caused by shallow microwave penetration depth and super heating occurring at the solid–liquid interface. The kinetic study shows that the pressure leaching of copper anode slime, with and without microwave assisted pretreatment, are both controlled by chemical reactions on the surfaces of particles. It is found that the activation energy calculated for microwave-assisted pretreatment-pressure leaching (49.47 kJ/mol) is lower than that for pressure leaching which is without microwave assisted pretreatment (60.57 kJ/mol).

  2. Evaluation of heavy metal leaching from coal ash-versus conventional concrete monoliths and debris.

    Science.gov (United States)

    Gwenzi, Willis; Mupatsi, Nyarai M

    2016-03-01

    Application of coal ash in construction materials is constrained by the potential risk of heavy metal leaching. Limited information is available on the comparative heavy metal leaching from coal ash-versus conventional concrete. The current study compared total and leached heavy metal concentrations in unbound coal ash, cement and sand; and investigated the effect of initial leachant pH on heavy metal leaching from coal-ash versus conventional concrete monoliths and their debris. Total Pb, Mn and Zn in coal ash were lower than or similar to that of other materials, while Cu and Fe showed the opposite trend. Leached concentrations of Zn, Pb, Mn, Cu and Fe in unbound coal ash, its concrete and debris were comparable and in some cases even lower than that for conventional concrete. In all cases, leached concentrations accounted for just concrete was minimal and comparable to that of conventional concrete, a finding in contrast to widely held public perceptions and earlier results reported in other regions such as India. In the current study the coal ash, and its concrete and debris had highly alkaline pH indicative of high acid neutralizing and pH buffering capacity, which account for the stabilization of Zn, Pb, Mn, Cu and Fe. Based on the low risk of Zn, Pb, Mn, Cu and Fe leaching from the coal ash imply that such coal ash can be incorporated in construction materials such as concrete without adverse impacts on public and environmental health from these constituents.

  3. Soil column leaching of pesticides.

    Science.gov (United States)

    Katagi, Toshiyuki

    2013-01-01

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

  4. Leaching of boron, arsenic and selenium from sedimentary rocks: II. pH dependence, speciation and mechanisms of release

    Energy Technology Data Exchange (ETDEWEB)

    Tabelin, Carlito Baltazar, E-mail: carlito@trans-er.eng.hokudai.ac.jp [Laboratory of Soil Environment Engineering, Faculty of Engineering, Hokkaido University, Sapporo (Japan); Hashimoto, Ayaka, E-mail: a.hashimoto@diaconsult.co.jp [DIA Consultants Co. Ltd., Sapporo (Japan); Igarashi, Toshifumi, E-mail: tosifumi@eng.hokudai.ac.jp [Laboratory of Groundwater and Mass Transport, Faculty of Engineering, Hokkaido University, Sapporo (Japan); Yoneda, Tetsuro, E-mail: yonet@eng.hokudai.ac.jp [Laboratory of Soil Environment Engineering, Faculty of Engineering, Hokkaido University, Sapporo (Japan)

    2014-03-01

    Sedimentary rocks excavated in Japan from road- and railway-tunnel projects contain relatively low concentrations of hazardous trace elements like boron (B), arsenic (As) and selenium (Se). However, these seemingly harmless waste rocks often produced leachates with concentrations of hazardous trace elements that exceeded the environmental standards. In this study, the leaching behaviors and release mechanisms of B, As and Se were evaluated using batch leaching experiments, sequential extraction and geochemical modeling calculations. The results showed that B was mostly partitioned with the residual/crystalline phase that is relatively stable under normal environmental conditions. In contrast, the majority of As and Se were associated with the exchangeable and organics/sulfides phases that are unstable under oxidizing conditions. Dissolution of water-soluble phases controlled the leaching of B, As and Se from these rocks in the short term, but pyrite oxidation, calcite dissolution and adsorption/desorption reactions became more important in the long term. The mobilities of these trace elements were also strongly influenced by the pH of the rock-water system. Although the leaching of Se only increased in the acidic region, those of B and As were enhanced under both acidic and alkaline conditions. Under strongly acidic conditions, the primarily release mechanism of B, As and Se was the dissolution of mineral phases that incorporated and/or adsorbed these elements. Lower concentrations of these trace elements in the circumneutral pH range could be attributed to their strong adsorption onto minerals like Al-/Fe-oxyhydroxides and clays, which are inherently present and/or precipitated in the rock-water system. The leaching of As and B increased under strongly alkaline conditions because of enhanced desorption and pyrite oxidation while that of Se remained minimal due to its adsorption onto Fe-oxyhydroxides and co-precipitation with calcite. - Highlights: • The bulk of

  5. 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.)

  6. Acute Generalized Exanthematous Pustulosis Induced by Amoxicillin/Clavulanic Acid: Report of a Case Presenting With Generalized Lymphadenopathy.

    Science.gov (United States)

    Syrigou, Ekaterini; Grapsa, Dimitra; Charpidou, Andriani; Syrigos, Konstantinos

    2015-01-01

    Drug-induced acute generalized exanthematous pustulosis is a rare pustular skin reaction, most commonly triggered by antibiotics. Although its diagnosis is based primarily on the presence of specific clinical and histopathologic features, additional in vivo (patch testing) or in vitro testing may be required, especially in atypical cases, to more accurately determine the causative agent. The authors report a histologically confirmed case of acute generalized exanthematous pustulosis that was induced by amoxicillin/clavulanic acid, as documented by subsequent patch testing, and presented with generalized painful lymphadenopathy, mimicking an acute infectious process. This is a very rare and diagnostically challenging clinical presentation of acute generalized exanthematous pustulosis, which has been reported, to the best of our knowledge, only once previously.

  7. Uranium and thorium leached from uranium mill tailing of Guangdong Province, China and its implication for radiological risk.

    Science.gov (United States)

    Wang, J; Liu, J; Zhu, L; Qi, J Y; Chen, Y H; Xiao, T F; Fu, S M; Wang, C L; Li, J W

    2012-11-01

    The paper focused on the leaching behaviour of uranium (U) and thorium (Th) from uranium mill tailing collected from the Uranium Mill Plant in Northern Guangdong Province, China. Distilled water (pH 6) and sulphuric acid solution (pH 4 and 3) were used as solvent for the leaching over 22 weeks. It was found that the cumulative leach fraction from the mill tailing was 0.1, 0.1 and 0.7 % for U release, and overall 0.01 % for Th release, using distilled water, sulphuric acid solution of pH 4 and pH 3 as leaching agents, respectively. The results indicate that (1) the release of U and Th in uranium mill tailing is a slow and long-term process; (2) surface dissolution is the main mechanism for the release of U and Th when sulphuric acid solution of pH 3 is employed as the leaching agent; (3) both U and Th are released by diffusion when using sulphuric acid solution of pH 4 as the leaching agent and (4) U is released by surface dissolution, while Th is released by diffusion when using distilled water as the leaching agent. The implication for radiological risk in the real environment was also discussed.

  8. Uranium and thorium leached from uranium mill tailing of Guangdong province (CN)) and its implication for radiological risk

    International Nuclear Information System (INIS)

    The paper focused on the leaching behaviour of uranium (U) and thorium (Th) from uranium mill tailing collected from the Uranium Mill Plant in Northern Guangdong Province (CN)). Distilled water (pH 6) and sulphuric acid solution (pH 4 and 3) were used as solvent for the leaching over 22 weeks. It was found that the cumulative leach fraction from the mill tailing was 0.1, 0.1 and 0.7 % for U release, and overall 0.01 % for Th release, using distilled water, sulphuric acid solution of pH 4 and pH 3 as leaching agents, respectively. The results indicate that (1) the release of U and Th in uranium mill tailing is a slow and long-term process; (2) surface dissolution is the main mechanism for the release of U and Th when sulphuric acid solution of pH 3 is employed as the leaching agent; (3) both U and Th are released by diffusion when using sulphuric acid solution of pH 4 as the leaching agent and (4) U is released by surface dissolution, while Th is released by diffusion when using distilled water as the leaching agent. The implication for radiological risk in the real environment was also discussed. (authors)

  9. Selective process of zinc extraction from spent Zn–MnO2 batteries by ammonium chloride leaching

    OpenAIRE

    Nogueira, C. A.; Margarido, F.

    2015-01-01

    Recycling of spent Zn-MnO2 batteries by hydrometallurgy is usually carried out by leaching in acid media, mainly with sulphuric acid solutions. Another type of leachant was used in this work, specifically solutions of concentrated ammonium chloride. The development of this study has relied on the prediction of the chemical behavior of the constituting phases based on data obtained from theoretical and experimental equilibrium values. The assessment of the effects of factors on leaching effici...

  10. 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.

  11. Leaching dynamics of uranium in a contaminated soil site

    International Nuclear Information System (INIS)

    Samples from a potentially contaminated industrial area were analyzed for uranium using neutron activation analysis (NAA). Uranium concentration values had a typical uncertainty of 2 % and a detection limit of 1 Bq/kg. To investigate the potential leaching dynamics into ground water two techniques were employed. The US EPA Toxicity Characterization Leaching Procedure (TCLP) and the Sequential Extraction Procedure (SEP) were used to determine the concentration of uranium in the leachates. TCLP and SEP showed that very little of the uranium leached into solution under different chemical conditions. Values of uranium leachates ranged from 0.05 to 3.5 Bq/L; a concentration much lower than the results found in the soil concentrations which ranged from 29 to 155 Bq/kg. NAA showed an 8 % uncertainty for leachates with a detection limit of 0.13 Bq/L. To mimic environmental conditions and acid rain, pH 4.3 water was used as the extraction solvent instead of the acetic acid routinely used in TCLP. Results confirmed that very low amounts of uranium leached with values ranging from 0.0002 to 0.0122 Bq/L. These values represent 0.01-1 % of the uranium in the soil samples. The distribution of uranium in soil according to particle size was also investigated to evaluate its potential movement and possible contamination of the water table. Particles below 250 μm in diameter showed a linear increase in uranium concentration whereas those with a larger diameter had constant uranium content. (author)

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

    Directory of Open Access Journals (Sweden)

    Tarun Sharma

    2015-11-01

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

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

    OpenAIRE

    Takahashi, Shigeru; Sakai, Etsuo; Sugiyama, Takafumi

    2007-01-01

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

  14. Atrazine leaching from biochar-amended soils.

    Science.gov (United States)

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

    2014-01-01

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

  15. Atrazine leaching from biochar-amended soils.

    Science.gov (United States)

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

    2014-01-01

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

  16. Leaching of Oil from Tuna Fish Liver by Using Solvent of Methyl-Ethyl Ketone

    Directory of Open Access Journals (Sweden)

    Mirna Rahmah Lubis

    2013-12-01

    Full Text Available Research of oil leaching from Tuna Fish Liver has been carried out by extracting of tuna fish liver in soxhlet by using methyl-ethyl ketone as solvent. Liver of fresh tuna fish is blended, put into soxhlet, and extracted at temperatures of 60oC, 65oC, 70oC, 75oC, and 80oC. After obtaining the oil, separation between solvent and oil is carried out by distillation. Oil obtained is analyzed by testing the yield, acid number, Iodine value, viscosity, and its impurities content. Yield obtained is influenced by temperature and time of leaching. Both variables indicates that the higher the variables, the more fish liver oil obtained. Maximum yield obtained is 25.552% at operating condition of leaching temperature 80oC, and leaching duration of 5 hours.

  17. 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...

  18. Leaching of tritium from a cement composite

    International Nuclear Information System (INIS)

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

  19. 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.

  20. 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.  

  1. pH-dependent leaching of dump coal ash - retrospective environmental analysis

    Energy Technology Data Exchange (ETDEWEB)

    Popovic, A.; Djordjevic, D. [University of Belgrade, Belgrade (Serbia). Dept. of Chemistry

    2009-07-01

    Trace and major elements in coal ash particles from dump of 'Nikola Tesla A' power plant in Obrenovac near Belgrade (Serbia) can cause pollution, due to leaching by atmospheric and surface waters. In order to assess this leaching potential, dump ash samples were subjected to extraction with solutions of decreasing pH values (8.50, 7.00, 5.50, and 4.00), imitating the reactions of the alkaline ash particles with the possible alkaline, neutral, and acidic (e.g., acid rain) waters. The most recently deposited ash represents the greatest environmental threat, while 'aged' ash, because of permanent leaching on the dump, was shown to have already lost this pollution potential. On the basis of the determined leachability, it was possible to perform an estimation of the acidity of the regional rainfalls in the last decades.

  2. Use of an acidophilic yeast strain to enable the growth of leaching bacteria on solid media.

    Science.gov (United States)

    Ngom, Baba; Liang, Yili; Liu, Yi; Yin, Huaqun; Liu, Xueduan

    2015-03-01

    In this study, a Candida digboiensis strain was isolated from a heap leaching plant in Zambia and used in double-layer agar plate to efficiently isolate and purify leaching bacteria. Unlike Acidiphilium sp., the yeast strain was tetrathionate tolerant and could metabolize a great range of organic compounds including organic acids. These properties allowed the yeast strain to enable and fasten the growth of iron and sulfur oxidizers on double-layer agar plate. The isolates were identified as Acidithiobacillus ferrooxidans FOX1, Leptospirillun ferriphilum BN, and Acidithiobacillus thiooxidans ZMB. These three leaching bacteria were inhibited by organic acids such as acetic and propionic acids; however, their activities were enhanced by Candida digboiensis NB under dissolved organic matter stress.

  3. Effect of processing history of pyrite on its leaching kinetics

    Institute of Scientific and Technical Information of China (English)

    赵中伟; 李洪桂; 孙培梅; 李运姣; 霍广生

    2003-01-01

    Different researchers often attained scattered kinetic results for the same leaching process. Usually, the difference is ascribed to the variation in mineral resource, chemical composition and, accuracy of experimental methods, while less attention is paid to the sample processing history. The present study shows that processing history of pyrite sample can cause great changes in its physico-chemical properties. Crushing, grinding and milling lead to an increase of the leachability of pyrite and the leaching becomes less temperature dependence owing to the decreasing of apparent activation energy of the reaction. The activation energy for its leaching in H2SO4-HNO3 solution is depressed from 73.9 to 47.5kJ/mol after being activated through vibrating milling for 40min. On the contrary, aging causes the reverse change owing to the release of extra inner energy stored during mechanical treatments. Thus activity of pyrite will decrease towards its original value. Surely the processing history of concentrate sample should be taken into consideration when studying the kinetics of leaching reaction.

  4. 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.

  5. Dynamic leaching test of personal computer components.

    Science.gov (United States)

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

    2009-11-15

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

  6. Leach-SX-EW copper revalorization from overburden of abandoned copper mine Cerovo, Eastern Serbia

    Directory of Open Access Journals (Sweden)

    Stevanović Z.

    2009-01-01

    Full Text Available Hydrometallurgical processes for copper revalorization from overburden of abandoned mine Cerovo in Eastern Serbia were studied. Paper contain results of percolation leaching tests, performed with acidic mine waters accumulated in the bottom of the former open pit, followed by solvent extraction (SX and electrowinning (EW processes on achieved copper pregnant leach solutions. Usage of accumulated waste waters was objected to minimizing the environmental hazard due to uncontrolled leaking of these waters in nearby creeks and rivers. Chemical composition of acidic mine waters used for leaching tests was: (g/dm3: Cu - 0.201; Fe - 0.095; Mn - 0.041; Zn - 0.026; Ni - 0.0004; pH value - 3.3. Copper content in overburden sample used for leaching tests was 0.21% from which 64% were oxide copper minerals. In scope of leaching tests were examined influence of leaching solution pH values and iron (III concentration on copper recovery. It was established that for 120 hours of leaching on pH=1.5 without oxidant agents, copper concentration in pregnant leach solutions enriched up to 1.08g/dm3 which was enough for copper extraction from solution with SX-EW treatment. As extraction reagent in SX circuit was used LIX-984N in a kerosene diluent. Cathode current density in electrowinning cell was 220Am-2 while electrolyte temperature was kept on 50±2oC. Produced cathode copper at the end of SX-EW process has purity of 99.95% Cu.

  7. 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.

  8. CHARACTERIZATION OF TANK 16H ANNULUS SAMPLES PART II: LEACHING RESULTS

    Energy Technology Data Exchange (ETDEWEB)

    Hay, M.; Reboul, S.

    2012-06-19

    The closure of Tank 16H will require removal of material from the annulus of the tank. Samples from Tank 16H annulus were characterized and tested to provide information to evaluate various alternatives for removing the annulus waste. The analysis found all four annulus samples to be composed mainly of Si, Na, and Al and lesser amounts of other elements. The XRD data indicate quartz (SiO{sub 2}) and sodium aluminum nitrate silicate hydrate (Na{sub 8}(Al{sub 6}Si{sub 6}O{sub 24})(NO{sub 3}){sub 2}.4H{sub 2}O) as the predominant crystalline mineral phases in the samples. The XRD data also indicate the presence of crystalline sodium nitrate (NaNO{sub 3}), sodium nitrite (NaNO{sub 2}), gibbsite (Al(OH){sub 3}), hydrated sodium bicarbonate (Na{sub 3}H(CO{sub 3}){sub 2}.2H{sub 2}O), and muscovite (KAl{sub 2}(AlSi{sub 3}O{sub 10})(OH){sub 2}). Based on the weight of solids remaining at the end of the test, the water leaching test results indicate 20-35% of the solids dissolved after three contacts with an approximately 3:1 volume of water at 45 C. The chemical analysis of the leachates and the XRD results of the remaining solids indicate sodium salts of nitrate, nitrite, sulfate, and possibly carbonate/bicarbonate make up the majority of the dissolved material. The majority of these salts were dissolved in the first water contact and simply diluted with each subsequent water contact. The water leaching removed large amounts of the uranium in two of the samples and approximately 1/3 of the {sup 99}Tc from all four samples. Most of the other radionuclides analyzed showed low solubility in the water leaching test. The oxalic acid leaching test result indicate approximately 34-47% of the solids in the four annulus samples will dissolve after three contacts with an approximately 3:1 volume of acid to solids at 45 C. The same sodium salts found in the water leaching test comprise the majority of dissolved material in the oxalic acid leaching test. However, the oxalic acid was

  9. 氧压酸浸处理锌焙砂中浸渣的新工艺研究%Research on Oxidizing Pressure Leaching the Residues from the Neutral Leaching Process

    Institute of Scientific and Technical Information of China (English)

    张向阳; 王吉坤; 巨佳; 徐静; 谢红艳; 贺山明

    2012-01-01

    Zinc calcine leaching process by three-stage, there are neutral leaching-low acid leaching-high acid leaching. Iron would be leaching into the solution in the process of acid leaching which would increase the difficulty of removing iron before electro-deposition. In this paper, the traditional zinc hydrometallurgical and oxygen pressure leaching were combined, the effect of oxygen pressure, concentration of sulfuric acid, temperature, leaching time, mineral particles size, liquor/solid ratio and amount dispersing agentwere found out from the research on oxidizing pressure leaching the residues from the neutral leaching process. The results showed thatoxidizing pressure leaching have good economic benefit and social effect. It is not only improve Zn leaching rate( over 98% ) , reduce Fe leaching rate( low 50% ) , shorten pro- duction cycle and reduction in production costs, but also environment friendly and raising resource utilization. So as to simplify process and save energymeanwhile it can offered reference for industrial study in future.%锌焙砂一般采用中性-低酸-高酸三段浸出工序,该工艺在酸浸出中浸渣的过程中,铁也大量浸出进入到溶液中,加重了净化电积前除铁的负担。通过将传统锌湿法冶金工艺与氧压酸浸新工艺相结合,研究了氧压酸浸处理中浸渣的氧气压力、硫酸浓度、温度、浸出时间、粒度、液固比和分散剂等相关因素的影响。实验结果表明该工艺不仅提高了锌的浸出率(〉98%),降低了铁的浸出率(〈50%),缩短了生产周期,降低了生产成本,具有良好的经济效益;而且还具有环境友好和资源利用率高等优点,实现了简化工艺和节能减排的目的,为工业化生产提供了参考.

  10. Leaching Behaviors of Gallium and Germanium in Zinc Sulfide Concentrate during High Oxygen Pressure Leach Process%硫化锌精矿中镓锗在高压氧浸中的浸出行为研究

    Institute of Scientific and Technical Information of China (English)

    徐毅

    2011-01-01

    试验研究了硫化锌精矿中镓、锗在高压氧浸中的浸出行为,考察确定了酸锌的量比,浸出时间,浸出液初始Fe(II)离子浓度,木质素添加量,矿石粒度,温度等因素对各元素浸出率的影响。结果表明,锗与锌的浸出行为较为一致;而镓与铁的浸出行为密切相关,使铁充分浸出并保持浸出液具有足够的酸度,防止高温下Fe(II)离子的氧化水解,是提高金属镓浸出率的关键。对富含镓、锗等稀散金属的硫化锌精矿,采用两段逆流流程浸出,既可保证镓、锗浸出率在80%以上,又能使得一段浸出后液酸度p(H2SO4)〈20g/L,从而有利于其后续的中和%The leaching behaviors of Ga and Ge in ZnS concentrate during high oxygen pressure leach process wereinvestigated experimentally. The effects of molar ratio of sulfuric acid to zinc, leach time, initial Fe^2+ concentration in the leach solution, additive amount of sodium lignosulfonic acid, particle size of concentrate and temperature on the leach efficiencies of such elements as Zn, Fe, Ga and Ge were evaluated. The results show that the leach efficiency of Ge is in accord with that of zinc, while the leach efficiency of Ga is relative to that of Fe closely. The key of raising leach efficiency of Ga is to leach Fe in the concentrate adequately, as well as to maintain the acidity of leach solution and protect Fe^2+ from oxidation-hydrolysis at high temperature. It is reasonable that using a two-steps countercurrent leach process to treat zinc sulfide concentrate with high content of Ga and Ge, not only can obtain higher leach efficiencies of Ga and Ge, but also make the acidity of the after leach solution less than 20 gH2SO4/L. It is beneficial to the subsequent neutralization.

  11. Dinâmica de íons em solo ácido lixiviado com extratos de resíduos de adubos verdes e soluções puras de ácidos orgânicos Dynamic of ions in acid soil leached with green manure residues extracts and pure solutions of organic acids

    Directory of Open Access Journals (Sweden)

    Júlio Cezar Franchini

    1999-12-01

    Full Text Available A influência da aplicação de resíduos vegetais na dinâmica de íons em solos ácidos é pouco conhecida. Neste estudo, a mobilidade de íons em amostra do horizonte Bw de um Latossolo Vermelho-Escuro álico lixiviado com soluções puras de ácidos cítrico e succínico e extratos aquosos de resíduos de nabo forrageiro (Raphanus sativus e aveia-preta (Avena strigosa foi avaliada em colunas de solo (5, 10, 20 e 40 cm de altura por 4 cm de diâmetro. Após a percolação das soluções e extratos pelas colunas de solo determinaram-se, nas soluções efluentes, os teores de Ca (Ca s, Mg (Mg s, K (Ks, Al total (Al st, orgânico (Al so, monomérico (Al sm e carbono orgânico dissolvido. No solo, foram determinados os teores trocáveis de Ca (Ca tr, Mg (Mg tr, K (Ktr e Al (Al tr e o pH (CaCl2. Os ácidos cítrico e succínico aumentaram os teores de Al st e Ca s, respectivamente, causando reduções nas frações trocáveis desses elementos no solo. O extrato de aveia-preta foi mais efetivo na remoção do Ca tr e o de nabo forrageiro na do Al tr. O decréscimo de Ca tr e Al tr foi seguido do aumento do Ktr. A formação de complexos entre Ca s e Al tr com compostos orgânicos de baixo peso molecular foi sugerida como o provável mecanismo responsável pela mobilidade dos íons polivalentes no subsolo de solos ácidos após a aplicação dos extratos de resíduos vegetais e das soluções puras de ácidos orgânicos.The influence of green manure residues addition in the dynamic of ions in acid soils is not well known. In this study, ion mobility in a sample of the Bw horizon of an Dark-Red Latosol (Oxisol, leached with citric and succinic acid pure solutions and with aqueous residue extracts of black oats (Avena strigosa and oil seed radish (Raphanus sativus were evaluated in soil columns (5, 10, 20, and 40 cm long by 4 cm diameter. After the solutions and extracts passed through the soil columns, the following parameters were determined

  12. Loss of PCB and OCB during leaching tests; Verlies aan polychloorbifenylen (pcb) en organochloorbestrijdingsmiddelen (ocb) tijdens uitloogproeven

    Energy Technology Data Exchange (ETDEWEB)

    Rood, G.A.; Broekman, M.H.; Aalbers, T.G.

    1995-01-01

    Within the framework of the Target Plan for the normalization commission 39011 on `Leaching characteristics of building and waste materials`, the RIVM has developed a set of leaching tests for various organic compounds. These tests are based on the leaching tests for inorganic compounds. The leaching behavior of Polycyclic Aromatic Hydrocarbons (PAH) was first investigated by means of a column and a serial batch test, resulting in draft protocols. The specific objective of the research presented in this report was to examine these protocols on applicability for the determination of PCB (polychlorinated biphenyls) and exractable organohalogen compounds (EOX) leaching. The losses of these compounds during the leaching tests due to absorption, filtration, volatilization and light were evaluated. In general, the adsorptions of PCB and pesticides on materials made of glass, like the prefilter, glasswool and the bottle were lower than on those made of Teflon, like the rings, gauze and the tubing.

  13. 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.

  14. The leaching of lead from lead-based paint in landfill environments.

    Science.gov (United States)

    Wadanambi, Lakmini; Dubey, Brajesh; Townsend, Timothy

    2008-08-30

    Lead leaching from lead-based paint (LBP) was examined using standardized laboratory protocols and tests with leachate from actual and simulated landfill environments. Two different LBP samples were tested; leaching solutions included leachates from three municipal solid waste (MSW) landfills and three construction and demolition (C&D) debris landfills. The toxicity characteristic leaching procedure (TCLP) and the synthetic precipitation leaching procedure (SPLP) were also performed. Lead concentrations were many times higher using the TCLP compared to the SPLP and the landfill leachates. No significant difference (alpha=0.05) was observed in leached lead concentrations from the MSW landfill and C&D debris landfill leachates. The impact of other building materials present in LBP debris on lead leaching was examined by testing mixtures of LBP (2%) and different building materials (98%; steel, wood, drywall, concrete). The type of substrate present impacted lead leaching results, with concrete demonstrating the most dramatic impact; the lowest lead concentrations were measured in the presence of concrete under both TCLP and SPLP extractions.

  15. Geochemical characterization and leaching behavior of slags: by-product materials from an old lead smelter in Chihuahua, Mexico

    Science.gov (United States)

    Espejel-Garcia, D.; Wenglas-Lara, G.; Villalobos-Aragon, A.; Espejel-Garcia, V. V.

    2012-12-01

    Steel slags are stored in piles or stocks around or near the smelter site. Currently, there is an increasing interest in the use of waste materials, especially in the construction industry, to replace natural aggregates, help the environment and reduce the costs. Slags are being used widely as road ballast, road base or sub-base material, sandblasting agents or cement additives, but normally contain high concentrations of potentially toxic metals. Although these metals are associated with glass, silicate and oxide minerals, with slow solubilities in water, a characterization of the leaching behavior is essential in environmental evaluation for reuse scenarios. The state of Chihuahua is located in northern Mexico, and mining has been an important economic activity since the 18th century. In the early 1900's, a lead smelter operated in Avalos, Chihuahua (in the southern surroundings of Chihuahua city), and left considerable slag piles after their closure in the 1980's. In this study, this material has been geochemically analyzed to identify the metals contained in it, and used in "tank tests" experiments, to assess its leaching behavior. The slags from Chihuahua contain Pb (0.5 - 4 wt.%), Zn (15-35 wt.%) and As (0.6 wt.%) in different minerals such as hardystonite (Ca2ZnSi2O7), melanotekite (Pb2Fe3+3O2Si2O7), kentrolite (Pb2Mn2Si2O9) and sphalerite (ZnS) or trapped in the glass. Major elements are present in phases such as monticellite (CaMgSiO4), kirschsteinite (CaFe2+SiO4), hedenbergite (CaFeSi2O6), babingtonite (Fe2Si3O9), magnetite (Fe3O4), and calcite (CaCO3). The leaching experiments were performed for 6, 24, 168 and 360 hours in mixtures of 30 and 50% of slags with natural road base material using distilled water at a pH 5 and 8 to recreate acidic and alkaline waters. The amounts of leached Pb ranges from 0.1 to 0.5 ppm, Zn from 0.1 to 0.6 ppm, As from 0 to 0.09 ppm, and Ca from 40 to 180 ppm, being the acidic experiments the ones that leached out the highest

  16. Coal fly ash interaction with environmental fluids: Geochemical and strontium isotope results from combined column and batch leaching experiments

    International Nuclear Information System (INIS)

    Highlights: ► Element release during fly ash extraction experiments controlled by mineralogy. ► Strontium isotopes in fly ash are not homogenized during coal combustion. ► Element correlations with 87Sr/86Sr indicate chemically resistant silicate phase. ► Sr isotopes can uniquely identify fly ash fluids leaking into the environment. - Abstract: The major element and Sr isotope systematics and geochemistry of coal fly ash and its interactions with environmental waters were investigated using laboratory flow-through column leaching experiments (sodium carbonate, acetic acid, nitric acid) and sequential batch leaching experiments (water, acetic acid, hydrochloric acid). Column leaching of Class F fly ash samples shows rapid release of most major elements early in the leaching procedure, suggesting an association of these elements with soluble and surface bound phases. Delayed release of certain elements (e.g., Al, Fe, Si) signals gradual dissolution of more resistant silicate or glass phases as leaching continues. Strontium isotope results from both column and batch leaching experiments show a marked increase in 87Sr/86Sr ratio with continued leaching, yielding a total range of values from 0.7107 to 0.7138. For comparison, the isotopic composition of fluid output from a fly ash impoundment in West Virginia falls in a narrow range around 0.7124. The experimental data suggest the presence of a more resistant, highly radiogenic silicate phase that survives the combustion process and is leached after the more soluble minerals are removed. Strontium isotopic homogenization of minerals in coal does not always occur during the combustion process, despite the high temperatures encountered in the boiler. Early-released Sr tends to be isotopically uniform; thus the Sr isotopic composition of fly ash could be distinguishable from other sources and is a useful tool for quantifying the possible contribution of fly ash leaching to the total dissolved load in natural surface

  17. Coal fly ash interaction with environmental fluids: Geochemical and strontium isotope results from combined column and batch leaching experiments

    Energy Technology Data Exchange (ETDEWEB)

    Brubaker, Tonya M; Stewart, Brian W; Capo, Rosemary C; Schroeder, Karl T; Chapman, Elizabeth C; Spivak-Birndorf, Lev J; Vesper, Dorothy J; Cardone, Carol R; Rohar, Paul C

    2013-05-01

    The major element and Sr isotope systematics and geochemistry of coal fly ash and its interactions with environmental waters were investigated using laboratory flow-through column leaching experiments (sodium carbonate, acetic acid, nitric acid) and sequential batch leaching experiments (water, acetic acid, hydrochloric acid). Column leaching of Class F fly ash samples shows rapid release of most major elements early in the leaching procedure, suggesting an association of these elements with soluble and surface bound phases. Delayed release of certain elements (e.g., Al, Fe, Si) signals gradual dissolution of more resistant silicate or glass phases as leaching continues. Strontium isotope results from both column and batch leaching experiments show a marked increase in {sup 87}Sr/{sup 86}Sr ratio with continued leaching, yielding a total range of values from 0.7107 to 0.7138. For comparison, the isotopic composition of fluid output from a fly ash impoundment in West Virginia falls in a narrow range around 0.7124. The experimental data suggest the presence of a more resistant, highly radiogenic silicate phase that survives the combustion process and is leached after the more soluble minerals are removed. Strontium isotopic homogenization of minerals in coal does not always occur during the combustion process, despite the high temperatures encountered in the boiler. Early-released Sr tends to be isotopically uniform; thus the Sr isotopic composition of fly ash could be distinguishable from other sources and is a useful tool for quantifying the possible contribution of fly ash leaching to the total dissolved load in natural surface and ground waters.

  18. Modelling and simulation of concrete leaching under outdoor exposure conditions.

    Science.gov (United States)

    Schiopu, Nicoleta; Tiruta-Barna, Ligia; Jayr, Emmanuel; Méhu, Jacques; Moszkowicz, Pierre

    2009-02-15

    Recently, a demand regarding the assessment of release of dangerous substances from construction products was raised by European Commission which has issued the Mandate M/366 addressed to CEN. This action is in relation with the Essential Requirement No. 3 "Hygiene, Health and Environment" of the Construction Products Directive (89/106/EC). The potential hazard for environment and health may arise in different life cycle stages of a construction product. During the service life stage, the release of substances due to contact with the rain water is the main potential hazard source, as a consequence of the leaching phenomenon. The objective of this paper is to present the development of a coupled chemical-transport model for the case of a concrete based construction product, i.e. concrete paving slabs, exposed to rain water under outdoor exposure conditions. The development of the model is based on an iterative process of comparing the experimental results with the simulated results up to an acceptable fit. The experiments were conducted at laboratory scale (equilibrium and dynamic leaching tests) and field scale. The product was exposed for one year in two types of leaching scenarios under outdoor conditions, "runoff" and "stagnation", and the element release was monitored. The model was calibrated using the experimental data obtained at laboratory scale and validated against measured field data, by taking into account the specific rain water balance and the atmospheric CO2 uptake as input parameters. The numerical tool used in order to model and simulate the leaching behaviour was PHREEQC, coupled with the Lawrence Livermore National Laboratory (LLNL) thermodynamic data base. The simulation results are satisfying and the paper demonstrates the feasibility of the modelling approach for the leaching behaviour assessment of concrete type construction materials. PMID:19118868

  19. Groundwater restoration with in situ uranium leach mining

    International Nuclear Information System (INIS)

    In situ leach mining of uranium has developed into a major mining technology. Since 1975, when the first commercial mine was licensed in the United States, the percentage or uranium produced by in situ mining has steadily grown from 0.6 to 10 percent in 1980. Part of the reason for this growth is that in situ mining offers less initial capital investment, shorter start-up times, greater safety, and less labor than conventional mining methods. There is little disturbance of the surface terrain or surface waters, no mill tailings piles, and no large open pits, but in situ leaching mining does have environmental disadvantages. During the mining, large amounts of ground water are cirulated and there is some withdrawal from an area where aquifers constitute a major portion of the water supply for other purposes. When an ammonia-based leach system is used, the ammonium ion is introduced into an area where cation exchange on clays (and some production of nitrate) may occur. Also, injection of an oxidant with the leach solution causes valence and phase changes of indigenous elements such as As, Cu, Fe, Mo, Se, S, and V as well as U. Furthermore, the surrounding ground water can become contaminated by escape of the leach solution from the mining zone. This chapter presents an overview of the in situ mining technology, including uranium deposition, mining techniques, and ground water restoration alternatives. The latter part of the chapter covers the situation in South Texas. Economics and development of the industry, groundwater resources, regulation, and restoration activities are also reviewed

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

    Science.gov (United States)

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

    2016-11-01

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

  1. Determination of arsenic leaching from glazed and non-glazed Turkish traditional earthenware

    Energy Technology Data Exchange (ETDEWEB)

    Henden, Emur, E-mail: emur.henden@ege.edu.tr; Cataloglu, Rengin; Aksuner, Nur

    2011-07-01

    Glazed and non-glazed earthenware is traditionally and widely used in Turkey and most of the Mediterranean and the Middle East countries for cooking and conservation of foodstuff. Acid-leaching tests have been carried out to determine whether the use of glazed and non-glazed earthenware may constitute a human health hazard risk to the consumers. Earthenware was leached with 4% acetic acid and 1% citric acid solutions, and arsenic in the leachates was measured using hydride generation atomic absorption spectrometry. Arsenic concentrations in the leach solution of non-glazed potteries varied from 30.9 to 800 {mu}g L{sup -1}, while the glazed potteries varied generally from below the limit of detection (0.5 {mu}g L{sup -1}) to 30.6 {mu}g L{sup -1}, but in one poorly glazed series it reached to 110 {mu}g L{sup -1}. Therefore, the risk of arsenic poisoning by poorly glazed and non-glazed potteries is high enough to be of concern. It appears that this is the first study reporting arsenic release from earthenware into food. - Research highlights: {yields} Non-glazed and poorly glazed earthenware may cause a serious arsenic release into food, and drinking water. {yields} Good glazing can avoid or greatly reduce arsenic leaching into food. {yields} Leaching of arsenic from earthenware may cause serious health risk. {yields} This is a pioneering work showing arsenic risk due to earthenware.

  2. THE INFLUENCE OF SELECTED FACTORS ON THE LEACHING OF HEAVY METALS FROM SMELTER WASTE

    OpenAIRE

    Kamila Mizerna; Anna Król

    2015-01-01

    The paper presents the results of leaching research of selected heavy metals (Pb, Cu, Zn, Ni, Cd, Cr) from industrial waste. The impact of waste fragmentation on the level of heavy metals leaching was analyzed. The decrease of copper and zinc release and the increase of nickel leaching were observed with increasing grain size fraction of waste. Furthermore, release of contaminants in different ratio of liquid to solid (L/S = 10 dm3/kg and 2 dm3/kg) was studied. Higher concentrations of heavy ...

  3. Column leaching from biomass combustion ashes

    DEFF Research Database (Denmark)

    Maresca, Alberto; Astrup, Thomas Fruergaard

    2015-01-01

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

  4. Characterization of refractory behaviour of complex gold/silver ore by diagnostic leaching

    Institute of Scientific and Technical Information of China (English)

    O. CELEP; (I).ALP; H. DEVEC(I); M. VICIL

    2009-01-01

    The amenability of a refractory ore to the extraction of gold and silver by cyanide leaching was investigated. Diagnostic leaching tests were also performed to shed light on the refractory characteristics of ore. The leaching tests show that the extraction of gold and silver is consistently low, i.e. ≤47% and ≤19.2%, respectively, over a leaching period of 24 h. Even fine grinding (e.g. <38 μm) does not improve the recovery of gold and silver. Diagnostic leaching approach provides information into the cause of the refractoriness of the ore. The findings suggest that the refractoriness is induced by the dissemination and encapsulation of the very fine gold and silver particles largely in the carbonates, oxides and sulfides and, to a small extent, with silicates present in the ore matrix. These findings highlight the practical importance of diagnostic leaching for the understanding of the refractory characteristic of such an ore and for the identification of possible pretreatment options to overcome its refractoriness prior to cyanide leaching.

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

    Directory of Open Access Journals (Sweden)

    Kamila Mizerna

    2016-05-01

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

  6. Effect of ferrous metal presence on lead leaching in municipal waste incineration bottom ashes.

    Science.gov (United States)

    Oehmig, Wesley N; Roessler, Justin G; Zhang, Jianye; Townsend, Timothy G

    2015-01-01

    The recovery of ferrous and non-ferrous metals from waste to energy (WTE) ash continues to advance as the sale of removed metals improves the economics of waste combustion. Published literature suggests that Fe and Fe oxides play a role in suppressing Pb leaching in the Toxicity Characteristic Leaching Procedure (TCLP); further removal of ferrous metals from WTE ashes may facilitate higher Pb leaching under the TCLP. Eight WTE bottom ash size-fractions, from three facilities, were evaluated to assess the effect of metallic Fe addition and ferrous metal removal on TCLP leaching. Metallic Fe addition was demonstrated to reduce Pb leaching; the removal of ferrous metals by magnet resulted in a decrease in total available Pb (mg/kg) in most ash samples, yet Pb leachability increased in 5 of 6 ash samples. The research points to two chemical mechanisms to explain these results: redox interactions between Pb and Fe and the sorption of soluble Pb onto Fe oxide surfaces, as well as the effect of the leachate pH before and after metals recovery. The findings presented here indicate that generators, processors, and regulators of ash should be aware of the impact ferrous metal removal may have on Pb leaching, as a substantial increase in leaching may have significant implications regarding the management of WTE ashes. PMID:25464288

  7. Chemical ionization mass spectrometry (CIMS) may not measure all gas-phase sulfuric acid if base molecules are present

    OpenAIRE

    Kurtén, T.; T. Petäjä; Smith,J; Ortega, I.K.; Sipilä, M.; Junninen, H.; M. Ehn; Vehkamäki, H.; Mauldin, L.; Worsnop, D.R.; M. Kulmala

    2010-01-01

    The state-of-the art method for measuring atmospheric gas-phase sulfuric acid is chemical ionization mass spectrometry (CIMS) based on nitrate reagent ions. Using computed proton affinities and reaction thermodynamics for the relevant charging reactions, we show that in the presence of strong bases such as amines, which tend to cluster with the sulfuric acid molecules, a significant fraction of the total gas-phase sulfuric acid may not be measured by a CIMS instrument. If this is the c...

  8. 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.

  9. Rapid transport and transformation of phosphorus species during the leaching of poultry manure amended soil

    Science.gov (United States)

    Giles, Courtney; Cade-Menun, Barbara; Liu, Corey; Hill, Jane

    2015-04-01

    The loss of phosphorus (P) from soils due to leaching is a major concern in heavily fertilized agricultural regions. The mobility and transformation of P species will depend on the source of manure fertilizer, leaching regime, and the extent of soil P saturation within the soil profile. We investigate spatial and temporal changes in the distribution of P species within a poultry manure-amended soil at two depths (0-5, 10-15 cm) as well as leachate P fractions during 10 weeks of leaching. Leachate P was primarily composed of dissolved fractions (soluble reactive P; dissolved unreactive P) and reached a maximum in the fourth week of leaching. In soils, the degree of P saturation (80%) and water extractable P (9 mg kg-1) were also greatest in week 4. 31P NMR spectra of the 0-5 cm depth indicate that surface soils were most similar to the poultry manure in week 4. During peak leaching, the proportion of orthophosphate (OrthoP) at the soil surface (0-5 cm; 80%) was greater than that from the lowest depth (10-15 cm; 72%), which contained relatively larger proportions of monoester-(17%) and diester-P classes (10%). Poultry manure likely contributed to the mobile pool of P species, including OrthoP, myo-inositol hexakisphosphate (myo-IHP), and nucleic acids. The appearance of neo- and D-chiro-IHP, as well as phospholipid signals during the leaching period indicate possible short-term (organic P to the generation and leaching of OrthoP, under P-saturated conditions. Further work is needed to determine how fertilization and leaching will affect the mobility and transformation of P species across a wider range of soil types. Keywords: Phytate, organic phosphorus, degree of phosphorus saturation, soil, leachate, poultry manure

  10. [Characteristics of Adsorption Leaching and Influencing Factors of Dimethyl Phthalate in Purple Soil].

    Science.gov (United States)

    Wang, Qiang; Song, Jiao-yan; Zeng, Wei; Wang, Fa

    2016-02-15

    The typical soil-purple soil in Three Gorges Reservoir was the tested soil, the characteristics of adsorption leaching of dimethyl phthalate (DMP) in contaminated water by the soil, and the influencing factors in the process were conducted using soil column leaching experiment. The results showed that the parabolic equation was the best equation describing adsorption kinetics of DMP by soils. The concentration of DMP in the leaching solution had significant effect on the adsorption amounts of DMP. With the increasing concentration of DMP in the leaching solution, the adsorption capacities of DMP by purple soil increased linearly. The ionic strength and pH in leaching solution had significant effects on adsorption of DMP. On the whole, increasing of the ionic strength restrained the adsorption. The adsorption amounts at pH 5.0-7.0 were more than those under other pH condition. The addition of exogenous organic matter (OM) in purple soil increased the adsorption amount of DMP by purple soil. However, the adsorption amount was less than those with other addition amounts of exogenous OM when the addition of exogenous OM was too high (> or = 30 g x kg(-1)). The addition of surfactant sodium dodecylbenzene sulfonic acid (SDBS) in purple soil increased the adsorption amount of DMP by purple soil. The adsorption amount was maximal when the addition amount of SDBS was 50 mg x kg(-1). However, the adsorption amounts decreased with increasing addition amounts of SDBS although the adsorption amounts were still more than that of the control group, and the adsorption amount was almost equal to that of the control group when the addition amount of SDBS was 800 mg x kg(-1). Continuous leaching time affected the vertical distribution of DMP in the soil column. When the leaching time was shorter, the upper soil column adsorbed more DMP, while the DMP concentrations in upper and lower soil columns became similar with the extension of leaching time. PMID:27363166

  11. [Characteristics of Adsorption Leaching and Influencing Factors of Dimethyl Phthalate in Purple Soil].

    Science.gov (United States)

    Wang, Qiang; Song, Jiao-yan; Zeng, Wei; Wang, Fa

    2016-02-15

    The typical soil-purple soil in Three Gorges Reservoir was the tested soil, the characteristics of adsorption leaching of dimethyl phthalate (DMP) in contaminated water by the soil, and the influencing factors in the process were conducted using soil column leaching experiment. The results showed that the parabolic equation was the best equation describing adsorption kinetics of DMP by soils. The concentration of DMP in the leaching solution had significant effect on the adsorption amounts of DMP. With the increasing concentration of DMP in the leaching solution, the adsorption capacities of DMP by purple soil increased linearly. The ionic strength and pH in leaching solution had significant effects on adsorption of DMP. On the whole, increasing of the ionic strength restrained the adsorption. The adsorption amounts at pH 5.0-7.0 were more than those under other pH condition. The addition of exogenous organic matter (OM) in purple soil increased the adsorption amount of DMP by purple soil. However, the adsorption amount was less than those with other addition amounts of exogenous OM when the addition of exogenous OM was too high (> or = 30 g x kg(-1)). The addition of surfactant sodium dodecylbenzene sulfonic acid (SDBS) in purple soil increased the adsorption amount of DMP by purple soil. The adsorption amount was maximal when the addition amount of SDBS was 50 mg x kg(-1). However, the adsorption amounts decreased with increasing addition amounts of SDBS although the adsorption amounts were still more than that of the control group, and the adsorption amount was almost equal to that of the control group when the addition amount of SDBS was 800 mg x kg(-1). Continuous leaching time affected the vertical distribution of DMP in the soil column. When the leaching time was shorter, the upper soil column adsorbed more DMP, while the DMP concentrations in upper and lower soil columns became similar with the extension of leaching time.

  12. Bacterial leaching of metal sulfides proceeds by two indirect mechanisms via thiosulfate or via polysulfides and sulfur

    Energy Technology Data Exchange (ETDEWEB)

    Schippers, A.; Sand, W. [Univ. Hamburg (Germany). Inst. fuer Allgemeine Botanik

    1999-01-01

    Bacterial leaching, the biooxidation of metal sulfides to soluble metal sulfates and sulfuric acid, is effected by specialized bacteria. The acid-insoluble metal sulfides FeS{sub 2}, MoS{sub 2}, and WS{sub 2} are chemically attacked by iron(III) hexahydrate ions, generating thiosulfate, which is oxidized to sulfuric acid. Other metal sulfides are attacked by iron(III) ions and by protons, resulting in the formation of elemental sulfur via intermediary polysulfides. Sulfur is biooxidized to sulfuric acid. This explains leaching of metal sulfides by Thiobacillus thiooxidans.

  13. Pyrite Surface after Thiobacillus ferrooxidans Leaching at 30℃

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    In order to investigate the effect of Thiobacillus ferrooxidans on the oxidation of pyrite, two parallel experiments, which employed H2SO4 solutions and acidic solutions inoculated with Thiobacillus ferrooxidans, were designed and carried out at 30℃. The initial pH of the two solutions was adjusted to 2.5 by dropwise addition of concentrated sulphuric acid. The surfaces of pyrite before exposure to leaching solutions and after exposure to the H2SO4 solutions and acidic solutions inoculated with Thiobacillus ferrooxidans were observed by scanning electron microscopy (SEM). There were a variety of erosion patterns by Thiobacillusferrooxidans on the bio-leached pyrite surfaces. A conclusion can be drawn that the oxidation of pyrite might have been caused by erosion of the surfaces.Attachment of the bacteria to pyrite surfaces resulted in erosion pits, leading to the oxidation of pyrite.It is possible that the direct mechanism plays the most important role in the oxidation of pyrite. The changes in iron ion concentrations of both the experimental solutions with time suggest that Thiobacillus ferrooxidans can enhance greatly the oxidation of pyrite.

  14. 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.

  15. Uraniferous minerals heap leaching process by counter techique

    International Nuclear Information System (INIS)

    An experimental study was made at laboratory level with respect to a process for the treatment of an uranium ore by counter current acid heap leaching with maturity periods and washing. This mineral with an average grade of 0.24% of U3O8 from the levels zero-fourty of the El Nopal uraniferous deposit, located in the Sierra of Pena Blanca, State of Chihuahua (Mexico). The process which is proposed consist of 4 consecutive stages: a) The prehumectation with a fertile solution of a 0.0034 g U3O8/1 and 3 g H2SO4/l concentration, b) The counter current acid attack, c) The maturity or hardening, d) The washing with current water. The relaton liquid-solid in the stages of prehumectation, acid attack, as well as washing stage was of 0.3 m3/t. The average efficiency was of 77% of recovered *uranium. (author)

  16. Consumption of high doses of chlorogenic acid, present in coffee, or black tea increases plasma total homocysteine concentrations in humans

    NARCIS (Netherlands)

    Olthof, M.R.; Hollman, P.C.; Zock, P.L.; Katan, M.B.

    2001-01-01

    In population studies, high intakes of coffee are associated with raised concentrations of plasma homocysteine, a predictor of risk of cardiovascular disease. Chlorogenic acid is a major polyphenol in coffee; coffee drinkers consume up to 1 g chlorogenic acid/d. OBJECTIVE: We studied whether chlorog

  17. 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%.

  18. 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.

  19. 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.

  20. Optimization of the factors that accelerate leaching

    International Nuclear Information System (INIS)

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

  1. 含铁低品位氧化锌矿石浸出研究%Leaching of low grade zinc oxide ore bearing iron

    Institute of Scientific and Technical Information of China (English)

    杨金林; 马少健; 封金鹏; 王桂芳; 莫伟; 苏秀娟

    2011-01-01

    Alkaline leaching and sulfuric acid leaching of low grade zinc oxide ore bearing iron were studied in this work. The effecting factors, such as leaching time in different leaching agents and leaching temperature using ammonia-ammonium chloride as leaching agent, on zinc and iron leaching rates were investigated in alkaline leaching. The effecting factors, such as the initial sulfuric acid concentration, liquid-solid ratio, leaching temperature in different initial sulfuric acid concentrations and leaching time in different leaching temperatures, on zinc and iron leaching rates were studied in sulfuric acid leaching. The results showed that the leaching rates of zinc and iron were less than 50% and zero in alkaline leaching, respectively, while their leaching rates were greater than 87% and 45% in sulfuric acid leaching. The results of XRD analysis indicated that smithsonite was leached from the ore in alkaline leaching or in sulfuric acid leaching with low initial concentration such as less than 60 g/L or shorter time such as less than 10 min, and smithsonite and siderite were leached from the ore in sulfuric acid leaching with high initial concentration such as greater than 60 g/L or longer time such as more than 10 min.%针对含铁低品位氧化锌矿石,进行了碱性浸出与硫酸浸出研究.其中碱性浸出主要考察了采用不同浸出剂时浸出时间以及采用氨水——氯化铵作浸出剂时浸出温度对锌、铁浸出率的影响;硫酸浸出主要考察了硫酸初始浓度、矿浆液固比以及不同硫酸初始浓度时浸出温度和不同浸出温度时浸出时间对锌、铁浸出率的影响.研究结果表明,碱性浸出时锌浸出率不到50%,铁基本不被浸出;XRD分析结果说明,碱性浸出时浸出的主要是菱锌矿.硫酸浸出时锌浸出率最高可达87%以上,但铁的浸出率也在45%以上;XRD分析结果说明,硫酸浸出在低浓度如小于60 g/L或短浸出时间如10 min时浸出的主

  2. Leaching experiments to study the release of trace elements from mineral separates from Chinese coals

    International Nuclear Information System (INIS)

    Leaching experiments were carried out for two samples of mineral separates from Chinese coals for the purpose to simulate the release of trace elements in acid mine drainage. The leaching solution has a ferric ion concentration of 10-3M, pH ∼ 2. The experiments were carried out at room temperature. The grain size of the mineral separates is 75-130μm. The behavior of the release of eight trace elements (Co, Ni, Zn, Cd, Al, Cr, As, and Pb) were measured during the period of 312h. The results from four leaching tests using two samples with two solid-to-liquid ratios show that the concentrations of Co, Ni, Zn, and Cd continuously increased during the leaching period and they were correlated with the sulfate content in the same leachate. This indicates that the elements were released during the oxidation and dissolution of pyrite. The elements were easily dissolved in the leaching solution. On the other hand, the concentrations of Al, Cr, As, and Pb in the leachates varied considerably under same leaching conditions and were sensitive to the condition of the leachate during the leaching process. The release of these four elements was affected by the pH of the leachate and by absorption and co-precipitation. They are less likely to migrate. Therefore, the release and migration of the eight elements in acid coal-mine drainage are controlled mainly by three factors, the oxidation of pyrite, the pH of the leachate, and mineralogy of country rocks. (author)

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

    Institute of Scientific and Technical Information of China (English)

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

    2007-01-01

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

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

    Institute of Scientific and Technical Information of China (English)

    李怀仁; 陈家辉; 徐庆鑫; 和晓才; 翟中标

    2011-01-01

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

  5. Studies on the trans-fatty acids and the stability of the fats present in Indian bakery products

    Directory of Open Access Journals (Sweden)

    Shariff, R.

    2013-03-01

    Full Text Available Fat is one of the most important ingredients in baked products which is highly susceptible to heat and moisture. Therefore, this study has been conducted to assess the thermoxidative changes occurring in the fat as well as the extent to which trans-fatty acids are present. Fats were extracted from products like rusk, white bread, sweet bun, dilkhush, pizza, plain cake, vegetable roll, gluco-biscuits and wafers. These fats and control shortening samples were taken for study. The totox value was found to be high (4.0-30.9 whereas the free fatty acid, peroxide and anisidine values were, 0.31-0.90%, 1.2-11.0 and 11.6-8.9 respectively. Since the products are baked at 180 to 200 °C polar components were determined to be between 3.3 to 5.3% showing a moderate hydrolysis and oxidative changes. Iodine value (51.0 to 73.3 and the Butyro-refractometer reading (42.2 to 55.8 showed moderate unsaturation and all the samples melted below 37 °C. Trans-fatty acid ranged from 35.5 to 46.2% as has also been confirmed by FT-IR. The products selected were considered safe but nutritionally inferior to products prepared with liquid shortenings.La grasa es uno de los ingredientes más importantes de los productos horneados altamente susceptible al calor y la humedad. Se han realizado estudios para evaluar los cambios termoxidativos ocurridos en las grasas y también la presencia de ácidos grasos trans. Las grasas se extrajeron de productos como galletas, pan blanco, pan dulce, Dilkhush, pizza, pastel, rollo vegetal, gluco-galletas y barquillos. Se utilizaron en este estudio las grasas extraidas de los mencionados productos, así como muestras control de shortening. Los valor encontrados de índice Totox fueron altos (4,0-30,9 en tanto que los porcentajes de ácidos grasos libres (%, índice de peróxido y anisidina fueron, 0,31-0,90, 1,2-11,0 y 11,6- 8,9, respectivamente. Puesto que los productos se hornean entre 180-200 °C se determinaron los componentes polares

  6. Leaching behaviour of the Swedish KBS-glasses ABS 39 and ABS 41

    International Nuclear Information System (INIS)

    The planned Swedish KBS glass corrosion investigation program comprises experiments with inactive glasses containing simulated waste, prolonged in-situ tests, the characterization of corrosion products, immiscibility studies, and corrosion experiments with hot glass. This presentation gives a short description of the entire program. It focuses thereafter on some recent leaching results with the inactive KBS glass qualities ABS 39 and ABS 41, which were leached in a manner similar to the PNL MCC-1 test procedure. 5 figures, 9 tables

  7. Leaching of selected heavy metals from electronic waste in the presence of the At. ferrooxidans bacteria

    OpenAIRE

    J. Willner

    2012-01-01

    Purpose: This paper presents the experimental work carried out to evaluate the leaching efficiency of zinc, nickel and lead from printed circuit boards (PCBs) using biological leaching with different quantities of acidophilic bacteria as inoculum.Design/methodology/approach: Bioleaching was conducted using periodic method in Erlenmneyer flasks, with pure cultures of At. ferrooxidans. Some conditional parameters: oxidation-reduction potential, pH were taken into account.Findings: The results d...

  8. Study on the Change of Soil Organic Matter Content of Moisture Soil in Pearl River Delta by High Intensity Simulated Acid Rain Leaching Experiment%高强度模拟酸雨淋滤珠江三角洲地区潮土的有机质含量变化研究

    Institute of Scientific and Technical Information of China (English)

    李展强; 杨晓艳; 曾宇斌; 陈福

    2011-01-01

    采用高强度(平均离子强下10年、20年、30年雨量)模拟酸雨淋滤珠江三角洲地区的潮土,用重铬酸钾滴定法测定淋滤后土壤的有机质含量。研究表明:高强度模拟酸雨对土壤有机质含量的影响不大。各层土有机质含量变化最大的为下降13.04%,最小的为-1.33%。%The moisture soil in Pearl Rivet Delta was leached by high intensity(ten,twenty and thirty years rainfall amount) simulated acid rain and the content of soil organic matter was determined by titration with potassium dichromate.The study showed that the high intensity simulated acid rain had little influence on the change of soil organic matter content.The maximum percent of decrement of soil organic matter content was 13.04 %,and the minimum was-1.33 %.

  9. One-year leaching of three SRL glasses in granite

    International Nuclear Information System (INIS)

    Three Savannah River Laboratory (SRL) simulated nuclear waste glasses were buried in granite boreholes 345 meters deep. Included in the same boreholes were other potential waste package components including stainless steel and bentonite. Samples were maintained at either ambient mine temperature (8 to 100C) or 900C. Differences in the leaching performances were observed among the three compositions, with SRL 165 being more durable than SRL 131, both with 29.8% TDS waste. Likewise, the presence of some package components affected the leaching performances. Bentonite resulted in accelerated attack on the glass while the presence of stainless steel did not appear to have much affect. Results obtained through one year of burial are presented. 6 refs., 5 figs., 2 tabs

  10. Equilibrium leach testing of Magnox swarf and sludge

    International Nuclear Information System (INIS)

    A static equilibrium leach test has been developed to simulate repository conditions after ground water has penetrated the near field barrier. The repository components - waste, matrix and backfill - have been equilibrated with water for up to one year. Leachates were analysed for U, Pu, Np237, Am241, Cs137, Sr90, Tc99, I129 and C14. Results are presented for leaching from Magnox fuel cladding wastes using a combination of matrices, backfills and atmospheric conditions. The equilibrium concentrations were generally very low and have been compared with the concentration of each isotope in drinking water that would give an adult an annual effective dose equivalent of 0.1mSv. (author)

  11. An approximation method for diffusion based leaching models

    International Nuclear Information System (INIS)

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

  12. 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.

  13. Coupling between chemical degradation and mechanical behaviour of leached concrete

    International Nuclear Information System (INIS)

    This work is in the context of the long term behavior of concrete employed in radioactive waste disposal. The objective is to study the coupled chemo-mechanical modelling of concrete. In the first part of this contribution, experimental investigations are described where the effects of the calcium leaching process of concrete on its mechanical properties are highlighted. An accelerated method has been chosen to perform this leaching process by using an ammonium nitrate solution. In the second part, we present a coupled phenomenological chemo-mechanical model that represents the degradation of concrete materials. On one hand, the chemical behavior is described by the simplified calcium leaching approach of cement paste and mortar. Then a homogenization approach using the asymptotic development is presented to take into account the influence of the presence of aggregates in concrete. And on the other hand, the mechanical part of the modelling is given. Here continuum damage mechanics is used to describe the mechanical degradation of concrete. The growth of inelastic strains observed during the mechanical tests is describes by means of a plastic like model. The model is established on the basis of the thermodynamics of irreversible processes framework. The coupled nonlinear problem at hand is addressed within the context of the finite element method. Finally, numerical simulations are compared with the experimental results for validation. (author)

  14. The determination, by x-ray-fluorescence spectrometry, of noble and base metals in matte-leach residues

    International Nuclear Information System (INIS)

    An accurate and precise method is described for the determination of noble and base metals in matte-leach residues. Preparation of the samples essentially involves fusion with sodium peroxide in a zirconium crucible and leaching with hydrochloric and nitric acids. Matrix correction and calibration are achieved by use of the single-standard calibration method with reference solutions prepared from pure metals or from compounds of the element to be determined

  15. Removal of lead from cathode ray tube funnel glass by combined thermal treatment and leaching processes.

    Science.gov (United States)

    Okada, Takashi; Nishimura, Fumihiro; Yonezawa, Susumu

    2015-11-01

    The reduction melting process is useful to recover toxic lead from cathode ray tube funnel glass; however, this process generates SiO2-containing residues that are disposed in landfill sites. To reduce the volume of landfill waste, it is desirable to recycle the SiO2-containing residues. In this study, SiO2 powder was recovered from the residue generated by reduction melting. The funnel glass was treated by a process combining reduction melting at 1000°C and annealing at 700°C to recover a large quantity of lead from the glass. The oxide phase generated by the thermal treatment was subjected to water leaching and acid leaching with 1M hydrochloric acid to wash out unwanted non-SiO2 elements for SiO2 purification. In the water washing, the oxide phase was microparticulated, and porous structures formed on the oxide surfaces. This increased the surface area of the oxide phase, and the unwanted elements were effectively washed out during the subsequent acid leaching. By controlling the acid leaching time and the amount of added acid, porous and amorphous SiO2 (purity >95 wt%) was recovered. In the obtained SiO2-concentrated product, unrecovered lead remained at concentrations of 0.25-0.79 wt%. When the Na2CO3 dosage in the thermal treatment was increased, the lead removal by acid leaching was enhanced, and the lead concentration in the obtained product decreased to 0.016 wt%. PMID:26022339

  16. Production of fermented probiotic beverages from milk permeate enriched with whey retentate and identification of present lactic acid bacteria

    OpenAIRE

    Jagoda Šušković; Slavko Kirin; Stjepan Mahnet; Jadranka Frece; Jasna Beganović; Josip Turk; Andreja Leboš Pavunc

    2009-01-01

    In this research the application of bacterial strains Lactobacillus acidophilus M92, Lactobacillus plantarum L4 and Enterococcus faecium L3 in the production of fermented probiotic beverages from milk permeate enriched with 10 % (v/v) whey retentate, was investigated. In the previous researches of probiotic concept, probiotic properties of these three strains of lactic acid bacteria have been defined. At the end of controlled fermentation, probiotic strains have produced 7.4 g/L lactic acid, ...

  17. Simplified process for leaching precious metals from fuel cell membrane electrode assemblies

    Science.gov (United States)

    Shore, Lawrence; Matlin, Ramail

    2009-12-22

    The membrane electrode assemblies of fuel cells are recycled to recover the catalyst precious metals from the assemblies. The assemblies are cryogenically embrittled and pulverized to form a powder. The pulverized assemblies are then mixed with a surfactant to form a paste which is contacted with an acid solution to leach precious metals from the pulverized membranes.

  18. Does microbial cm-scale heterogeneity impact pesticide degradation in and leaching from loamy agricultural soils?

    DEFF Research Database (Denmark)

    Rosenbom, Annette Elisabeth; Binning, Philip John; Aamand, Jens;

    2014-01-01

    The potential for pesticide degradation varies greatly at the cm-scale in agricultural soil. Three dimensional numerical simulations were conducted to evaluate how such small-scale spatial heterogeneity may affect the leaching of the biodegradable pesticide 2-methyl-4-chlorophenoxyacetic acid (MC...

  19. About instant neutrons fission logging use under uranium extraction by the in situ leaching method

    International Nuclear Information System (INIS)

    One aspect of wide range of tasks, which can be solved by the instant neutron of fission logging method in the process of the geological-exploration works for uranium is discussed in the paper: aims, tasks, and possibilities of the method for the in situ acid leaching of uranium. (author)

  20. New phosphate-based binder for stabilization of soils contaminated with heavy metals: leaching, strength and microstructure characterization.

    Science.gov (United States)

    Du, Yan-Jun; Wei, Ming-Li; Reddy, Krishna R; Jin, Fei; Wu, Hao-Liang; Liu, Zhi-Bin

    2014-12-15

    Cement stabilization is used extensively to remediate soils contaminated with heavy metals. However, previous studies suggest that the elevated zinc (Zn) and lead (Pb) concentrations in the contaminated soils would substantially retard the cement hydration, leading to the deterioration of the performance of cement stabilized soils. This study presents a new binder, KMP, composed of oxalic acid-activated phosphate rock, monopotassium phosphate and reactive magnesia. The effectiveness of stabilization using this binder is investigated on soils spiked with Zn and Pb, individually and together. Several series of tests are conducted including toxicity characteristic leaching (TCLP), ecotoxicity in terms of luminescent bacteria test and unconfined compressive strength. The leachability of a field Zn- and Pb- contaminated soil stabilized with KMP is also evaluated by TCLP leaching test. The results show that the leached Zn concentrations are lower than the China MEP regulatory limit except when Zn and Pb coexist and for the curing time of 7 days. On the other hand, the leached Pb concentrations for stabilized soils with Pb alone or mixed Zn and Pb contamination are much lower than the China MEP or USEPA regulatory limit, irrespective of the curing time. The luminescent bacteria test results show that the toxicity of the stabilized soils has been reduced considerably and is classified as slightly toxic class. The unconfined compressive strength of the soils decrease with the increase in the Zn concentration. The stabilized soils with mixed Zn and Pb contaminants exhibit notably higher leached Zn concentration, while there is lower unconfined compressive strength relative to the soils when contaminated with Zn alone. The X-ray diffraction and scanning electron microscope analyses reveal the presence of bobierrite (Mg3(PO4)2·8H2O) and K-struvite (MgKPO4·6H2O) as the main products formed in the KMP stabilized uncontaminated soils; the formation of hopeite (Zn3(PO4)2·4H2O

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

    Energy Technology Data Exchange (ETDEWEB)

    Bayat, Belgin, E-mail: bbayat@cu.edu.tr [Department of Environmental Engineering, Faculty of Engineering and Architecture, Cukurova University, Balcali, Adana 01330 (Turkey); Sari, Bulent [Department of Environmental Engineering, Faculty of Engineering and Architecture, Cukurova University, Balcali, Adana 01330 (Turkey)

    2010-02-15

    The purpose of the study described in this paper was to evaluate the application of bioleaching technique involving Acidithiobacillus ferrooxidans to recover heavy metals (Zn, Cu, Ni, Pb, Cd and Cr) in dewatered metal plating sludge (with no sulfide or sulfate compounds). The effect of some conditional parameters (i.e. pH, oxidation-reduction potential (ORP), sulfate production) and operational parameters (i.e. pulp density of the sludge and agitation time) were investigated in a 3 l completely mixed batch (CMB) reactor. The metal recovery yields in bioleaching were also compared with chemical leaching of the sludge waste using commercial inorganic acids (sulfuric acids and ferric chloride). The leaching of heavy metals increased with decreasing of pH and increasing of ORP and sulfate production during the bioleaching experiment. Optimum pulp density for bioleaching was observed at 2% (w/v), and leaching efficiency decreased with increasing pulp density in bioleaching experiments. Maximum metal solubilization (97% of Zn, 96% of Cu, 93% of Ni, 84% of Pb, 67% of Cd and 34% of Cr) was achieved at pH 2, solids contents of 2% (w/v), and a reaction temperature of 25 {+-} 2 deg. C during the bioleaching process. The maximum removal efficiencies of 72% and 79% Zn, 70% and 75% Cu, 69% and 73% Ni, 57% and 70% Pb, 55% and 65% Cd, and 11% and 22% Cr were also attained with the chemical leaching using sulfuric acids and ferric chloride, respectively, at pH 2, solids contents of 2% (w/v), and a reaction temperature of 25 {+-} 2 deg. C during the acid leaching processes. The rates of metal leaching for bioleaching and chemical leaching are well described by a kinetic equation related to time. Although bioleaching generally requires a longer period of operation compared to chemical leaching, it achieves higher removal efficiency for heavy metals. The efficiency of leaching processes can be arranged in descending order as follows: bioleaching > ferric chloride leaching > sulfuric

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

    International Nuclear Information System (INIS)

    The purpose of the study described in this paper was to evaluate the application of bioleaching technique involving Acidithiobacillus ferrooxidans to recover heavy metals (Zn, Cu, Ni, Pb, Cd and Cr) in dewatered metal plating sludge (with no sulfide or sulfate compounds). The effect of some conditional parameters (i.e. pH, oxidation-reduction potential (ORP), sulfate production) and operational parameters (i.e. pulp density of the sludge and agitation time) were investigated in a 3 l completely mixed batch (CMB) reactor. The metal recovery yields in bioleaching were also compared with chemical leaching of the sludge waste using commercial inorganic acids (sulfuric acids and ferric chloride). The leaching of heavy metals increased with decreasing of pH and increasing of ORP and sulfate production during the bioleaching experiment. Optimum pulp density for bioleaching was observed at 2% (w/v), and leaching efficiency decreased with increasing pulp density in bioleaching experiments. Maximum metal solubilization (97% of Zn, 96% of Cu, 93% of Ni, 84% of Pb, 67% of Cd and 34% of Cr) was achieved at pH 2, solids contents of 2% (w/v), and a reaction temperature of 25 ± 2 deg. C during the bioleaching process. The maximum removal efficiencies of 72% and 79% Zn, 70% and 75% Cu, 69% and 73% Ni, 57% and 70% Pb, 55% and 65% Cd, and 11% and 22% Cr were also attained with the chemical leaching using sulfuric acids and ferric chloride, respectively, at pH 2, solids contents of 2% (w/v), and a reaction temperature of 25 ± 2 deg. C during the acid leaching processes. The rates of metal leaching for bioleaching and chemical leaching are well described by a kinetic equation related to time. Although bioleaching generally requires a longer period of operation compared to chemical leaching, it achieves higher removal efficiency for heavy metals. The efficiency of leaching processes can be arranged in descending order as follows: bioleaching > ferric chloride leaching > sulfuric acid

  3. 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.

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

    Science.gov (United States)

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

    2016-07-01

    A major source of germanium recovery and also the source of this research is the by-product of lead and zinc metallurgical process. The primary purpose of the research is to investigate the effects of ultrasonic assisted and regular methods on the leaching yield of germanium from roasted slag containing germanium. In the study, the HCl-CaCl2 mixed solution is adopted as the reacting system and the Ca(ClO)2 used as the oxidant. Through six single factor (leaching time, temperature, amount of Ca(ClO)2, acid concentration, concentration of CaCl2 solution, ultrasonic power) experiments and the comparison of the two methods, it is found the optimum collective of germanium for ultrasonic-assisted method is obtained at temperature 80 °C for a leaching duration of 40 min. The optimum concentration for hydrochloric acid, CaCl2 and oxidizing agent are identified to be 3.5 mol/L, 150 g/L and 58.33 g/L, respectively. In addition, 700 W is the best ultrasonic power and an over-high power is adverse in the leaching process. Under the optimum condition, the recovery of germanium could reach up to 92.7%. While, the optimum leaching condition for regular leaching method is same to ultrasonic-assisted method, except regular method consume 100 min and the leaching rate of Ge 88.35% is lower about 4.35%. All in all, the experiment manifests that the leaching time can be reduced by as much as 60% and the leaching rate of Ge can be increased by 3-5% with the application of ultrasonic tool, which is mainly thanks to the mechanical action of ultrasonic. PMID:26964934

  5. Determination of Trace Phthalic Acid Esters in Leaching Solution of Plastic Food Packaging by Single-Drop Microextraction-Gas Chromatography%单滴微萃取-气相色谱法测定塑料食品包装浸出液中邻苯二甲酸酯类物质

    Institute of Scientific and Technical Information of China (English)

    张聪敏

    2011-01-01

    The determination methods for three kinds of phthalic acid esters in leaching solution of plastic food packaging using Single-drop microextraction ( SDME ) couple with gas chromatography-hydrogen flame ionization detector (GC-FID) was developed in this study. The optimum conditions for the assay were detected and listed as follows: with 1. 4 μL xylene as the organic extractant, extraction time 20 min, the extraction temperature 40°C , stiring speed 200 rpm. Under the optimum conditions, the DMP, DEP and DBP had the linear range of 0. 1-100 μg/mL and the detection limits were 0. 01 μg/mL. The actual sample recovery was 97-113. 9% d. This method is proved to be a simple, fast and low cost approach for determination of trace phthalic acid esters in leaching solution of plastic food packaging.%建立了基于单滴微萃取(SDME)结合气相色谱法测定塑料食品包装浸出液中3种邻苯二甲酸酯类物质含量的新方法.研究了萃取溶剂、萃取时间及搅拌速度等因素对萃取效率的影响,确定萃取的最佳条件:以1.4 μL二甲苯为萃取剂,萃取时间为20 min,萃取温度为40℃,搅拌速度为200 r/min.在最优条件下,该方法的线性范围为0.1~100 μg/mL,检出限为0.01 μg/mL,实际样品的加标回收率为97%~113.9%.本法具有简单、快速和成本低等特点.

  6. 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.

  7. 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.

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

    Science.gov (United States)

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

    2016-02-01

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

  9. Interaction of uranium(VI) with bioligands present in human biological fluids. The case study of urea and uric acid

    Energy Technology Data Exchange (ETDEWEB)

    Osman, A.A.A.; Geipel, G.; Bernhard, G. [Helmholtz-Zentrum Dresden-Rossendorf, Dresden (Germany). Inst. of Resource Ecology

    2013-05-01

    The complexation of uranium(VI) with bioligands found in human biological fluids, viz, urea and uric acid in aqueous solutions, has been investigated using time-resolved laser-induced fluorescence spectroscopy (TRLFS) at room temperature, I = 0.1 M (NaClO4) and pH (3 for uric acid; 4 for urea). In both complex systems a static quench effect with increasing ligand concentration and no peaks shift upon complexation were observed. With uranium(VI) both ligands formed a fairly weak 1:1 complex with average stability constants of log {beta}{sub 110} = 4.67 {+-} 0.29 for uric acid and log {beta}{sub 110} = 3.79 {+-} 0.15 and 2.12 {+-} 0.18 for relatively low and relatively high urea concentrations, respectively. Application of the newly generated data on the U(VI) speciation modelling in biofluids, e.g., human urine was also discussed.

  10. Selective leaching studies of deep-sea sediments loaded with americium, neptunium and plutonium

    International Nuclear Information System (INIS)

    A series of selective leaching experiments were undertaken to investigate the solid phase speciation and distribution of americium, neptunium and plutonium which had been experimentally loaded onto different marine sediment types. The chemical leaches employed showed rather poor selectivity but certain trends were evident. Adsorption was not by ion exchange. Americium showed a preferential affinity for carbonate and plutonium for organic matter. Neptunium appeared to have no preferential affinities. Americium was sorbed by acetic acid residues (CaCO3 removed) and by unleached carbonate-rich sediments with equal efficiency. This indicates that it is able to diversify its solid phase affinity/distribution depending upon which solid phases are available. (author)

  11. Kinetics of leaching of the aluminum hydroxide in bauxites by alkaline solutions at atmospheric pressure

    Science.gov (United States)

    Burtsev, A. V.; Lainer, Yu. A.; Gorichev, I. G.; Kipriyanov, N. A.; Izotov, A. D.

    2011-11-01

    The kinetics of leaching of the aluminum hydroxide from the gibbsite bauxites of Guinea (Kindia deposit) is studied under atmospheric conditions. The activation energy of the process is found to be 34.75 kJ/mol, which indicates that the process proceeds in a kinetic mode. The leaching of the aluminum hydroxide from bauxite in an alkaline solution is simulated using acid-base equilibria (ion exchange) and the electrochemical theory of the structure of a double electrical layer (Gram-Parsons theory).

  12. Development of SO2-O2 system as an oxidant at uranium leaching processes

    International Nuclear Information System (INIS)

    The oxidation of Fe2+ in uranium leaching solutions with gaseous mixture of SO2 and air has been studied. The variables studied include H2SO4 concentration, temperature, SO2 concentration and time. The oxidation rate was founded to increase greatly with an increase in the solution temperature. The almost total oxidation of Fe2+ is readily achieved at 95 deg C. By appropriately adjusting the temperature of solution and SO2/O2 in the gas, oxidation of ferrous ion and generation of sulphuric acid can be carried out. It was founded that solutions produced by such oxidation processing are very suitable for the uranium ore leaching. (author)

  13. Influence of Drain Spacing upon the Quantity of Nitrogen Leached

    Directory of Open Access Journals (Sweden)

    Lepomir Čoga

    2003-03-01

    Full Text Available The research goal was to determine the influence of drainpipe spacing onthe quantity of nitrogen leached, under standard agricultural practices, in the ecological conditions of eastern Slavonija. The field trial was set up at the agroecological station Kapelna-Donji Miholjac in the period 1993-1994, on amphigley soil, drained through an open channel network and drainpipes spaced 10, 20 and 40 m, according to the split-plot method with three replications. Winter wheat, cultivar Marija, served as test crop. Research results revealed differences in the concentration of nitrate and ammonium nitrogen in soil, depending on drainpipe spacing, plot location and sampling time. Significantly lower concentrations of nitrate nitrogen were recorded on plots overlying drainpipes compared to the plots situated between drainpipes, regardless of drainpipe spacing. Nitrogen in drainage water and groundwater was mainly present in the nitrate form. The highest average concentration of nitrate nitrogen in drainage water of 25.9 mg NO3-N / l and in groundwater of 16.7 mg NO3-N / l were recorded at the drainpipe spacing of 10 m, and the lowest at the drainpipe spacing of 40 m. The significantly highest quantity of leached nitrogen of 11.2 kg N/ha was recorded at the drainpipe spacing of 10 m, whereas differences in the leached nitrogen quantities between drainpipe spacing of 20 and 40 m were not significant. The relatively small quantities of nitrogen leached, despite high nitrate concentrations in drainage water, resulted from the low drainage discharge during the trial period.

  14. Analysis of factors affecting the effect of stope leaching

    International Nuclear Information System (INIS)

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

  15. Reductive leaching behavior of zinc from neutral leaching residue in zinc smelting%锌冶炼中浸渣锌还原浸出行为研究

    Institute of Scientific and Technical Information of China (English)

    闵小波; 张建强; 张纯; 王密; 周波生; 沈忱

    2015-01-01

    以湿法炼锌中浸渣为研究对象,通过对比几种不同类型还原剂对中浸渣中铁酸锌浸出效果,筛选铁酸锌高效还原浸出药剂-硫酸肼,并考察硫酸肼浓度、时间、初始酸度、温度及液固比对锌浸出效果的影响.探讨浸出过程中锌物相转变机制.在浸出初始阶段主要是锌的硫酸盐、氧化物、硅酸盐及硫化物等易溶态溶出,而铁酸锌在浸出120 min后大部分溶出.在优化条件下Zn和Fe的浸出率分别达到了95.83%和94.19%.%This paper describes the behavior of reductive leaching of zinc from neutral leaching residue in zinc smelting. The effective reductant of hydrazine sulfate was selected by investigating the extraction efficiency of zinc from neutral leaching residue in zinc hydrometallurgical process among various types of reductant. The effects of initial concentration of hydrazine sulfate and sulfuric acid, retention, temperature and liquid-solid ratio on extraction were studied. Furthermore the transformation of zinc phases during the leaching was illustrated. The sulfate, oxide, silicate and sulfide of zinc were extracted fast at first and zinc ferrite was mostly leached out after reaction for 120 min. The leaching efficiencies of Zn and Fe were 95.83 % and 94.19 %respectively in optimum conditions.

  16. 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.

  17. Major leaching processes of combustion residues - Characterisation, modelling and experimental investigation

    Energy Technology Data Exchange (ETDEWEB)

    Yan Jinying

    1998-12-31

    Characterising leaching behaviour provides ample evidence to identify the major leaching processes of combustion residues. Neutralisation and chemical weathering govern the leaching reactions and control the release of elements from combustion residues, and are thus considered to be the major leaching processes. According to experimental investigations and geochemical simulations, the leaching kinetics of buffering materials are key issues for the understanding of the neutralizing processes. The acid neutralizing capacity at different pH levels depends mainly on the mineralogy of the combustion residues. In combustion residues, the dissolution of glass phases is expected to play an important role in a long-term neutralizing process. The neutralizing process in a flow system is significantly different from that in a batch system. The neutralizing ability of a combustion residue may be strongly affected by solute transport and carbonation reactions in a natural leaching environment. The chemical weathering mainly involves the matrix of combustion residues consisting mostly of glass phases. The dissolution kinetics of waste glass and other possible processes involved in the chemical weathering have been investigated and incorporated into a kinetic reactive transport model. Most important processes in the chemical weathering can be simulated simultaneously using this model. The results show that there is a complicated relationship between the factors controlling the long-term chemical weathering. The environmental impact of the glass dissolution cannot be neglected. Although the glass dissolution provides considerable buffering capacity in long-term weathering, the carbonate is usually a dominant buffering mineral in actual weathering processes. The transformation of carbonate should be considered as an important process in the chemical weathering. The formation of secondary minerals may considerably alter the mineralogy of the waste, and thus change the leaching

  18. Influences of ammonia contamination on leaching from air-pollution-control residues.

    Science.gov (United States)

    Guan, Zhenzhen; Chen, Dezhen; Astrup, Thomas Fruergaard

    2014-12-01

    Application of selective non-catalytic reduction systems at municipal solid waste incinerators (MSWIs) often involves over-stoichiometric injection of ammonia into flue gases. Un-reacted ammonia may be deposited on fly ash particles and can ultimately influence the leaching behaviour of air-pollution-control (APC) residues. Batch tests were conducted to investigate the impacts of ammonia levels on leaching of a range of metals (sodium, potassium, calcium, aluminium, chromium, iron, lead, cadmium, copper, nickel and zinc), as well as chloride and dissolved organic carbon (DOC). Specific conductivity was also identified to reflect the soluble components. The results showed that with ammonia concentrations rising from a background level of 4 to 26,400 mg l(-1), the specific conductivity increased by 2-7 times as pH varied from alkaline to acidic values. DOC release was also significantly enhanced with high ammonia levels of 1400 mg l(-1) or higher at pH > 9; however at these high ammonia concentrations, the role of DOC in cadmium, copper, nickel and zinc leaching was negligible. Based on the experimental data, chloride, sodium and potassium were leached at high concentrations regardless of pH and ammonia concentrations. For aluminium, chromium, iron and lead, ammonia had little impact on their leaching behaviour. With respect to cadmium, copper, nickel and zinc, high ammonia concentrations significantly increased leaching in the pH range of 8-12 due to the formation of metal-ammonia complexes, which was also proved in the speciation calculations. However, the overall results suggest that typical levels of ammonia injection in MSWIs are not likely to affect metal leaching from APC residues. PMID:25147306

  19. WAViS server for handling, visualization and presentation of multiple alignments of nucleotide or amino acids sequences.

    Science.gov (United States)

    Zika, Radek; Paces, Jan; Pavlícek, Adam; Paces, Václav

    2004-07-01

    Web Alignment Visualization Server contains a set of web-tools designed for quick generation of publication-quality color figures of multiple alignments of nucleotide or amino acids sequences. It can be used for identification of conserved regions and gaps within many sequences using only common web browsers. The server is accessible at http://wavis.img.cas.cz.

  20. WAViS server for handling, visualization and presentation of multiple alignments of nucleotide or amino acids sequences

    OpenAIRE

    Zika, Radek; Pačes, Jan; Pavlíček, Adam; Pačes, Václav

    2004-01-01

    Web Alignment Visualization Server contains a set of web-tools designed for quick generation of publication-quality color figures of multiple alignments of nucleotide or amino acids sequences. It can be used for identification of conserved regions and gaps within many sequences using only common web browsers. The server is accessible at http://wavis.img.cas.cz.