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Sample records for acid leaching present

  1. 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.

  2. 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.

  3. 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.

  4. Mechanochemical leaching of chalcopyrite concentrate by sulfuric acid

    Science.gov (United States)

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

    2016-04-01

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

  5. 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.

  6. 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+.

  7. Kinetic Aspects of Leaching Zinc from Waste Galvanizing Zinc by Using Hydrochloric Acid Solutions

    Science.gov (United States)

    Sminčáková, Emília; Trpčevská, Jarmila; Pirošková, Jana

    2016-10-01

    In this work, the results of acid leaching of flux skimmings coming from two plants are presented. Sample A contained two phases, Zn(OH)Cl and NH4Cl. In sample B, the presence of three phases, Zn5(OH)8Cl2·H2O, (NH4)2(ZnCl4) and ZnCl2(NH3)2, was proved. The aqueous solution of hydrochloric acid and distilled water was used as the leaching medium. The effects of the leaching time, temperature and concentration of the leaching medium on the zinc extraction were investigated. The apparent activation energy, E a = 4.61 kJ mol-1, and apparent reaction order n = 0.18 for sample A, and the values E a = 6.28 kJ mol-1 and n = 0.33 for sample B were experimentally determined. Zinc leaching in acid medium is a diffusion-controlled process.

  8. 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.

  9. 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.

  10. 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.

  11. 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

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

    Science.gov (United States)

    Dreisinger, David

    2017-01-01

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

  13. Teaching Paleontology with an Acid-Leaching Facility.

    Science.gov (United States)

    Talent, John A.; And Others

    1987-01-01

    Described is an acid-leaching facility at Macquarie University in Australia for teaching paleontology. The facility is used for teaching both undergraduate and graduate students and for research by staff and graduate students. Drawings of the facility are included and courses are described. (Author/RH)

  14. Selective Leaching of Vanadium from Roasted Stone Coal by Dilute Sulfuric Acid Dephosphorization-Two-Stage Pressure Acid Leaching

    Directory of Open Access Journals (Sweden)

    Jun Huang

    2016-07-01

    Full Text Available A novel staged leaching process has been reported in this paper to selectively extract vanadium from roasted stone coal and the mechanisms have been clarified. Results showed that the leaching efficiency of V, Al, P and Fe was 80.46%, 12.24%, 0.67% and 3.12%, respectively, under the optimum dilute sulfuric acid dephosphorization (DSAD-two-stage pressure acid leaching (PAL conditions. The efficient separation of V from Fe, Al and P was realized. As apatite could be leached more easily than mica, the apatite could completely react with sulfuric acid, while the mica had almost no change in the DSAD process, which was the key aspect in realizing the effective separation of V from P. Similarly, the hydrolyzation of Fe and Al could be initiated more easily than that of V by decreasing the residual acid of leachate. The alunite and iron-sulphate compound generated in the first-stage PAL process resulted in the effective separation of V from Fe and Al.

  15. 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.

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

    Directory of Open Access Journals (Sweden)

    Sokić M.

    2012-01-01

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

  17. 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.

  18. Effect of acid rain pH on leaching behavior of cement stabilized lead-contaminated soil.

    Science.gov (United States)

    Du, Yan-Jun; Wei, Ming-Li; Reddy, Krishna R; Liu, Zhao-Peng; Jin, Fei

    2014-04-30

    Cement stabilization is a practical approach to remediate soils contaminated with high levels of lead. However, the potential for leaching of lead out of these stabilized soils under variable acid rain pH conditions is a major environmental concern. This study investigates the effects of acid rain on the leaching characteristics of cement stabilized lead contaminated soil under different pH conditions. Clean kaolin clay and the same soil spiked with 2% lead contamination are stabilized with cement contents of 12 and 18% and then cured for 28 days. The soil samples are then subjected to a series of accelerated leaching tests (or semi-dynamic leaching tests) using a simulated acid rain leachant prepared at pH 2.0, 4.0 or 7.0. The results show that the strongly acidic leachant (pH ∼2.0) significantly altered the leaching behavior of lead as well as calcium present in the soil. However, the differences in the leaching behavior of the soil when the leachant was mildly acidic (pH ∼4.0) and neutral (pH ∼7.0) prove to be minor. In addition, it is observed that the lead contamination and cement content levels can have a considerable impact on the leaching behavior of the soils. Overall, the leachability of lead and calcium is attributed to the stability of the hydration products and their consequent influence on the soil buffering capacity and structure.

  19. 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 acid. 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 k J/mol. Furthermore, the main products are TiC and SiO2 after leaching.

  20. 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.

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

    Institute of Scientific and Technical Information of China (English)

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

    2016-01-01

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

  2. 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.

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

    Directory of Open Access Journals (Sweden)

    Miroslav Sokić

    2014-03-01

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

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

    Science.gov (United States)

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

    2015-07-01

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

  5. Fast pyrolysis of organic acid leached wood, straw, hay and bagasse: Improved oil and sugar yields

    NARCIS (Netherlands)

    Oudenhoven, S.R.G; Westerhof, R.J.M.; Kersten, S.R.A.

    2015-01-01

    Organic acid leaching of pine wood, straw, bagasse and hay effectively reduced the amount of catalytically active alkali and alkaline earth metals (AAEMs). Using the (acetic) acid produced by pyrolysis as leaching agent, the AAEMs content could be reduced to 90–600 mg/kg. Tests with AAEMs impregnate

  6. Quantitative Leaching of a Spent Cell Phone Printed Circuit Board by Hydrochloric acid

    Directory of Open Access Journals (Sweden)

    Alafara A. Baba

    2014-07-01

    Full Text Available This paper presents a kinetic data on the hydrometallurgical recovery of some metal ions from a printed circuit board (PCB of a spent cell phone by hydrochloric acid leaching. The effects of acid concentration, temperature and particle diameter on the dissolution efficiency at various leaching time intervals were examined. The results of the leaching investigations showed that the powdered cell phone dissolution increases with increasing acid concentration, system temperature with decreasing particle diameter at 360 rpm. With 2M HCl solution, about 88.49% of the sample was dissolved within 120 minutes using 0.075-0.112 mm particle diameter at 800 C. The results of the study indicated that the dissolution reaction could be represented by a shrinking core model with surface chemical reaction. A value of 0.61, 60.67 kJ/mol and 12.9s-1 were calculated as reaction order, activation energy and frequency factor, respectively for the dissolution process.

  7. 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.

  8. Impurity removal process for high-purity silica production by acid leaching

    Directory of Open Access Journals (Sweden)

    Ezzaouia H.

    2012-06-01

    Full Text Available In our days obtaining silica sand with very high purity is a primordial stage in photovoltaic industry. The effects of acids on the removal of impurity from silica sand have been studied using leaching acids: mixture composed of HF/HCl/H2O with a volume composition of (1:7:24.The obtained material was characterized using Ultraviolet-Visible absorbance (UV-Vis and Inductively Coupled Plasma Atomic Emission Spectroscopy (ICP-AES. Results of the application of this technique show a significant reduction of the amounts of undesirable impurities present in natural silica (such as Co, Fe, Ca, Al, Mg ….

  9. 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.

  10. 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.

  11. 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.

  12. Experimental design and process analysis for acidic leaching of metal-rich glass wastes.

    Science.gov (United States)

    Tuncuk, A; Ciftci, H; Akcil, A; Ognyanova, A; Vegliò, F

    2010-05-01

    The removal of iron, titanium and aluminium from colourless and green waste glasses has been studied under various experimental conditions in order to optimize the process parameters and to decrease the metal content in the waste glass by acidic leaching. Statistical design of experiments and ANOVA (analysis of variance) were performed in order to determine the main effects and interactions between the investigated factors (sample ratio, acid concentration, temperature and leaching time). A full factorial experiment was performed by sulphuric acid leaching of glass for metal removal. After treating, the iron content was 530 ppm, corresponding to 1880 ppm initial concentration of Fe(2)O(3) in the original colourless sample. This result is achieved using 1M H(2)SO( 4) and 30% sample ratio at 90(o)C leaching temperature for 2 hours. The iron content in the green waste glass sample was reduced from 3350 ppm initial concentration to 2470 ppm after treating.

  13. Copper catalysis for enhancement of cobalt leaching and acid utilization efficiency in microbial fuel cells.

    Science.gov (United States)

    Liu, Yaxuan; Shen, Jingya; Huang, Liping; Wu, Dan

    2013-11-15

    Enhancement of both cobalt leaching from LiCoO2 and acid utilization efficiency (AUE) in microbial fuel cells (MFCs) was successfully achieved by the addition of Cu(II). A dosage of 10mg/L Cu(II) improved both cobalt leaching up to 308% and AUE of 171% compared to the controls with no presence of Cu(II). The apparent activation energy of cobalt leaching catalyzed by Cu(II) in MFCs was only 11.8 kJ/mol. These results demonstrate cobalt leaching in MFCs using Cu(II) as a catalyst may be an effective strategy for cobalt recovery and recycle of spent Li-ion batteries, and the evidence of influence factors including solid/liquid ratio, temperature, and pH and solution conductivity can contribute to improving understanding of and optimizing cobalt leaching catalyzed by Cu(II) in MFCs.

  14. 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.

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

    Institute of Scientific and Technical Information of China (English)

    张文娟; 杨金洪; 赵中伟; 王文强; 李江涛

    2016-01-01

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

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

    Directory of Open Access Journals (Sweden)

    Sokić Miroslav D.

    2010-01-01

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

  17. 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.

  18. 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.

  19. 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.

  20. 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.

  1. 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.

  2. Manganese ore tailing: optimization of acid leaching conditions and recovery of soluble manganese.

    Science.gov (United States)

    Santos, Olívia de Souza Heleno; Carvalho, Cornélio de Freitas; Silva, Gilmare Antônia da; Santos, Cláudio Gouvêa Dos

    2015-01-01

    Manganese recovery from industrial ore processing waste by means of leaching with sulfuric acid was the objective of this study. Experimental conditions were optimized by multivariate experimental design approaches. In order to study the factors affecting leaching, a screening step was used involving a full factorial design with central point for three variables in two levels (2(3)). The three variables studied were leaching time, concentration of sulfuric acid and sample amount. The three factors screened were shown to be relevant and therefore a Doehlert design was applied to determine the best working conditions for leaching and to build the response surface. By applying the best leaching conditions, the concentrations of 12.80 and 13.64 %w/w of manganese for the global sample and for the fraction -44 + 37 μm, respectively, were found. Microbeads of chitosan were tested for removal of leachate acidity and recovering of soluble manganese. Manganese recovery from the leachate was 95.4%. Upon drying the leachate, a solid containing mostly manganese sulfate was obtained, showing that the proposed optimized method is efficient for manganese recovery from ore tailings.

  3. 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.

  4. Experimental investigation of influence of acid rain on leaching and hydraulic characteristics of cement-based solidified/stabilized lead contaminated clay.

    Science.gov (United States)

    Du, Yan-Jun; Jiang, Ning-Jun; Shen, Shui-Long; Jin, Fei

    2012-07-30

    Remediation of contaminated lands in China urban areas is of great concern. Degradation of construction facilities caused by acid rain is a serious environmental pollution issue in China. This paper presents an investigation of the effects of acid rain on leaching and hydraulic properties of cement-based solidified/stabilized lead contaminated soil. Laboratory tests including infiltration test and soaking test are conducted. It is found that the soil hydraulic conductivity decreases with increase in the pore volume of flow of permeant liquids (acid rain and distilled water). The decreasing rate in the case of the acid rain is lower than that in the case of the distilled water. The soaking test results show that pH and the presence of sulfate ions of acid rain have considerable influence on the leached concentrations and leaching rate of calcium.

  5. 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

    2016-11-05

    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.

  6. 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

  7. 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.

  8. 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.

  9. 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...... intensity and the timing of rain events after glyphosate application....

  10. Leaching of heavy metals in acid mine drainage

    Energy Technology Data Exchange (ETDEWEB)

    Saria, L.; Shimaoka, T.; Miyawaki, K. [Kyushu University, Fukuoka (Japan)

    2006-04-15

    Acid mine drainage is one of the most serious environmental problems that the coal and metal mining industry is currently facing. The generation of low pH drainage enhances the dissolution of heavy metals in water. The samples used in this research originated from three pits at mine dumps. In a study reported in this paper, three types of tests; namely static test, kinetic test and column test were conducted to estimate acid generation and acid neutralization reaction rates, and to predict the solubility of metals and their release rates. Static test showed that all samples had a pH of net acid generation (NAG pH) <4, a net acid producing potential (NAPP) >10 kg H{sub 2}SO{sub 4}tonne{sup -1}, and a S-content >3%, which can be classified as a high acid-forming capacity. Simulated runoff in the column tests was equivalent to 5-year average rainfall in Indonesia, the resultant leachates showed acidic behaviour (pH <3.5). Based on the results, it was found that high mobilization of heavy metals (Cr, Cu, Zn, Cd and Pb) takes place under strong acidic conditions (pH congruent to 2).

  11. 镍红土矿高压酸浸过程的金属元素浸出行为%Leaching behavior of metals from limonitic laterite ore by high pressure acid leaching

    Institute of Scientific and Technical Information of China (English)

    郭学益; 石文堂; 李栋; 田庆华

    2011-01-01

    以镍、钴的提取为目的,研究褐铁矿型镍红土矿高压酸浸过程中各金属元素的浸出行为,探讨硫酸加入量、浸出温度、浸出时间及液固比对各金属元素浸出率的影响.实验结果表明,在优化条件下Ni、Co、Mn和Mg的浸出率分别达到97%、96%、93%和95%以上,则Fe的浸出率小于1%.对高压浸出渣的分析表明,渣中的铁和硫主要分别以赤铁矿和明矾石的形式存在.高压浸出过程提供了一种从镍红土矿中提取镍和钴的简单有效的方法,同时产生具有利用价值的铁渣.%The leaching behavior of metals from a nickeliferous limonitic laterite ore was investigated by high pressure acid leaching process for the extraction of nickel and cobalt. The effects of sulfuric acid added, leaching temperature, leaching time and liquid/solid (L/S) ratio on metals extraction were examined. More than 97% Ni, 96% Co, 93% Mn, 95% Mg and less than 1% Fe are extracted under optimum conditions. Analysis of the high pressure acid leaching residue by chemical and XRD analysis indicates that the residual iron and sulfur are mainly present in phases of hematite and alunite, respectively. The high pressure leaching process provides a simple and efficient way for the high recovery of nickel and cobalt from laterite ore, leaving residue as a suitable iron resource.

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. 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

  17. Pressure leaching of metals from waste printed circuit boards using sulfuric acid

    Science.gov (United States)

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

    2011-08-01

    Printed circuit boards (PCBs) are essential components of electronic equipments which contain various metallic values. This paper reports a hydrometallurgical recycling process for waste PCBs, which consists of the novel pretreatment consisting of organic swelling of PCBs followed by sulfuric acid leaching of metals from waste PCBs. To recycle the waste PCBs, experiments were carried out for the recovery of copper from the crushed and organic swelled materials of waste PCBs using sulfuric acid leaching in presence of hydrogen peroxide under atmospheric and pressure condition. The leaching of PCBs at 90°C, pulp density 100 g/L under atmospheric condition, using 6M sulfuric acid resulted in the dissolution of a minor amount of copper due to the presence of plastic coating on the surface of metallic layers. On the other hand, when the liberated metal sheets from organic swelled PCBs were treated with dilute sulfuric acid of concentration 2M along with hydrogen peroxide in an autoclave under oxygen atmosphere, the percentage recovery of copper was found to increase from 59.63% to 97.01% with an increase in hydrogen peroxide concentration from 5 to 15% (v/v) keeping constant pulp density 30 g/L.

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

    Institute of Scientific and Technical Information of China (English)

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

    2016-01-01

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

  19. 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.

  20. 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.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2014-02-15

    Highlights: • A Brønsted acidic ILs was used to leach Cu from WPCBs for the first time. • The particle size of WPCBs has significant influence on Cu leaching rate. • Cu leaching rate was higher than 99% under the optimum leaching conditions. • The leaching process can be modeled with shrinking core model, and the E{sub a} was 25.36 kJ/mol. - Abstract: In this work, a Brønsted acidic ionic liquid, 1-butyl-3-methyl-imidazolium hydrogen sulfate ([bmim]HSO{sub 4}), was used to leach copper from waste printed circuit boards (WPCBs, mounted with electronic components) for the first time, and the leaching behavior of copper was discussed in detail. The results showed that after the pre-treatment, the metal distributions were different with the particle size: Cu, Zn and Al increased with the increasing particle size; while Ni, Sn and Pb were in the contrary. And the particle size has significant influence on copper leaching rate. Copper leaching rate was higher than 99%, almost 100%, when 1 g WPCBs powder was leached under the optimum conditions: particle size of 0.1–0.25 mm, 25 mL 80% (v/v) ionic liquid, 10 mL 30% hydrogen peroxide, solid/liquid ratio of 1/25, 70 °C and 2 h. Copper leaching by [bmim]HSO{sub 4} can be modeled with the shrinking core model, controlled by diffusion through a solid product layer, and the kinetic apparent activation energy has been calculated to be 25.36 kJ/mol.

  2. Dolomite phosphate rock (DPR) application in acidic sandy soil in reducing leaching of phosphorus and heavy metals-a column leaching study.

    Science.gov (United States)

    Yang, Yuangen; He, Zhenli; Yang, Xiaoe; Stoffella, Peter J

    2013-06-01

    A column leaching study was designed to investigate the leaching potential of phosphorus (P) and heavy metals from acidic sandy soils applied with dolomite phosphate rock (DPR) fertilizers containing varying amounts of DPR material and N-Viro soils. DPR fertilizers were made from DPR materials mixing with N-Viro soils at the ratios of 30, 40, 50, 60, and 70 %, and applied in acidic sandy soils at the level of 100 mg available P per kilogram soil. A control and a soluble P chemical fertilizer were also included. The amended soils were incubated at room temperature with 70 % field water holding capacity for 21 days before packed into a soil column and subjected to leaching. Seven leaching events were conducted at days 1, 3, 7, 14, 28, 56, and 70, respectively, and 258.9 mL of deionized water was applied at each leaching events. The leachate was collected for the analyses of pH, electrical conductivity (EC), dissolved organic carbon (DOC), major elements, and heavy metals. DPR fertilizer application resulted in elevations up to 1 unit in pH, 7-10 times in EC, and 20-40 times in K and Ca concentrations, but 3-10 times reduction in P concentration in the leachate as compared with the chemical fertilizer or the control. After seven leaching events, DPR fertilizers with adequate DPR materials significantly reduced cumulative leaching losses of Fe, P, Mn, Cu, and Zn by 20, 55, 3.7, 2.7, and 2.5 times than chemical fertilizer or control. Even though higher cumulative losses of Pb, Co, and Ni were observed after DPR fertilizer application, the loss of Pb, Co, and Ni in leachate was <0.10 mg (in total 1,812 mL leachate). Significant correlations of pH (negative) and DOC (positive) with Cu, Pb, and Zn (P<0.01) in leachate were observed. The results indicated that DPR fertilizers had a great advantage over the soluble chemical fertilizer in reducing P loss from the acidic sandy soil with minimal likelihood of heavy metal risk to the water environment. pH elevation and high

  3. 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%.

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

    Science.gov (United States)

    Byrne, Kelly; Hawker, William; Vaughan, James

    2017-01-01

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

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

    Institute of Scientific and Technical Information of China (English)

    蔡创开; 庄荣传; 林鸿汉

    2015-01-01

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

  6. Characterizing the release of different composition of dissolved organic matter in soil under acid rain leaching using three-dimensional excitation-emission matrix spectroscopy.

    Science.gov (United States)

    Liu, Li; Song, Cunyi; Yan, Zengguang; Li, Fasheng

    2009-09-01

    Although excitation-emission matrix spectroscopy (EEMS) has been widely used to characterize dissolved organic matter (DOM), there has no report that EEMS has been used to study the effects of acid rain on DOM and its composition in soil. In this work, we employed three-dimensional EEMS to characterize the compositions of DOM leached by simulated acid rain from red soil. The red soil was subjected to leaching of simulated acid rain of different acidity, and the leached DOM presented five main peaks in its EEMS: peak-A, related to humic acid-like (HA-like) material, at Ex/Em of 310-330/395-420nm; peak-B, related to UV fulvic acid-like (FA-like) material, at Ex/Em of 230-280/400-435nm; peak-C and peak-D, both related to microbial byproduct-like material, at Ex/Em of 250-280/335-355nm and 260-280/290-320nm, respectively; and peak-E, related to simple aromatic proteins, at Ex/Em of 210-240/290-340nm. EEMS analysis results indicated that most DOM could be lost from red soil in the early phase of acid rain leaching. In addition to the effects of the pH of acid rain, the loss of DOM also depended on the properties of its compositions and the solubility of their complexes with aluminum. HA-like and microbial byproduct-like materials could be more easily released from red soil by acid rain at both higher pH (4.5 and 5.6) and lower pH (2.5 and 3) than that at middle pH (3.5). On the contrary, FA-like material lost in a similar manner under the action of different acid rains with pH ranging from 2.5 to 5.6.

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

    Institute of Scientific and Technical Information of China (English)

    肖天祥

    2014-01-01

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

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

    Science.gov (United States)

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

    2015-05-01

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

  11. Leaching platinum-group metals in a sulfuric acid/chloride solution

    Science.gov (United States)

    Mahmoud, M. H. H.

    2003-04-01

    A leaching process was established based on the ability of platinum-group metals to form stable chloro-complexes in acidic chloride solutions. Industrial catalyst losses were examined for the recovery of platinum, palladium, and rhodium by leaching with a mixture of sulfuric acid and sodium chloride to avoid using aqua regia or autoclave conditions. Extraction of platinum and rhodium in 60% H2SO4 at 135°C steadily increased with increasing NaCl concentrations reaching 95% and 85%, respectively, at 0.1 M NaCl after two hours. By comparison, palladium was dissolved more quickly but also reached 85% under the same conditions. Extraction of each metal increased with temperatures up to 125°C but plateaued at higher temperatures. Similar behavior was observed with increasing H2SO4 concentrations up to 60%. More than 99% extraction of each metal was obtained after ten hours using 0.1 M NaCl and 60% H2SO4 at 125°C.

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

    Science.gov (United States)

    Chen, Xiangping; Chen, Yongbin; Zhou, Tao; Liu, Depei; Hu, Hang; Fan, Shaoyun

    2015-04-01

    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 CoC2O4 ⋅ 2H2O and Li2CO3 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.

  13. 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.

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

    Science.gov (United States)

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

    2010-06-15

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

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

    Science.gov (United States)

    Luyima, Alex; Shi, Honglan; Zhang, Lifeng

    2011-08-01

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

  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. Study on the leaching behavior of galena concentrate in fluosilicic acid solution using hydrogen peroxide as oxidant

    Science.gov (United States)

    Anugrah, Rezky Iriansyah; Mubarok, M. Zaki; Amalia, Dessy

    2017-01-01

    Lead (Pb) extraction from galena through leaching has not been commercialized in Indonesia. Therefore, the study of leaching behavior of Bogor galena concentrate in fluosilicic acid (H2SiF6) solution with hydrogen peroxide (H2O2) as oxidant was studied. The study was focused to investigate the effect of dissolution parameters such as temperature, stirring speed, solid percentage, acid concentration and particle sizes of the feed. The added oxidant (H2O2) was kept constant at 9.80 M. The result of Pb extraction percentage without oxidant addition was only 58.28% while by using oxidant in the leaching process, Pb extraction as high as 99.26% was achieved when conducted at 97 °C in 2.25 hours (135 minutes) using -100+150 mesh of concentrate in 3.44 M of H2SiF6 with 12% of solid percentage.

  18. Policy for metal leaching and acid rock drainage at mine sites in British Columbia

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1998-07-01

    One of the major environmental issues facing the provincial government of British Columbia is the prevention of environmental impacts from metal leaching and acid rock drainage (ML/ARD). The government`s major challenge in regulating ML/ARD is to ensure that all mines are planned and operated in a manner that allows for effective problem detection and mitigation, and that the mines emphasize problem prevention at the outset. This paper reviews the legislated requirements regarding ML/ARD prevention and lists guiding principles for the regulation of ML/ARD in the province. Some of the measures to predict and to mitigate ML/ARD include underwater storage of problematic materials, engineered covers, blending of wastes and drainage collection and treatment. Requirements applicable to construction materials, backfill, geotechnical and hydrological considerations, and security of funds for ML/ARD measures are also discussed.

  19. 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.

  20. A comparative study of solid carbon acid catalysts for the esterification of free fatty acids for biodiesel production. Evidence for the leaching of colloidal carbon.

    Science.gov (United States)

    Deshmane, Chinmay A; Wright, Marcus W; Lachgar, Abdessadek; Rohlfing, Matthew; Liu, Zhening; Le, James; Hanson, Brian E

    2013-11-01

    The preparation of a variety of sulfonated carbons and their use in the esterification of oleic acid is reported. All sulfonated materials show some loss in activity associated with the leaching of active sites. Exhaustive leaching shows that a finite amount of activity is lost from the carbons in the form of colloids. Fully leached catalysts show no loss in activity upon recycling. The best catalysts; 1, 3, and 6; show initial TOFs of 0.07 s(-1), 0.05 s(-1), and 0.14 s(-1), respectively. These compare favorably with literature values. Significantly, the leachate solutions obtained from catalysts 1, 3, and 6, also show excellent esterification activity. The results of TEM and catalyst poisoning experiments on the leachate solutions associate the catalytic activity of these solutions with carbon colloids. This mechanism for leaching active sites from sulfonated carbons is previously unrecognized.

  1. 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.

  2. 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.

  3. 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.

  4. Treatment of electronic waste to recover metal values using thermal plasma coupled with acid leaching--a response surface modeling approach.

    Science.gov (United States)

    Rath, Swagat S; Nayak, Pradeep; Mukherjee, P S; Roy Chaudhury, G; Mishra, B K

    2012-03-01

    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.

  5. 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

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

    Directory of Open Access Journals (Sweden)

    Bo Wang

    2017-03-01

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

  7. 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.

  8. Hazardous waste to materials: recovery of molybdenum and vanadium from acidic leach liquor of spent hydroprocessing catalyst using alamine 308.

    Science.gov (United States)

    Sahu, K K; Agrawal, Archana; Mishra, D

    2013-08-15

    Recovery of valuable materials/metals from waste goes hand in hand with environmental protection. This paper deals with the development of a process for the recovery of metals such as Mo, V, Ni, Al from spent hydroprocessing catalyst which may otherwise cause a nuisance if dumped untreated. A detailed study on the separation of molybdenum and vanadium from the leach solution of spent hydroprocessing catalyst of composition: 27.15% MoO₃, 1.7% V₂O₅, 3.75% NiO, 54.3% Al₂O₃, 2.3% SiO₂ and 10.4% LOI is reported in this paper. The catalyst was subjected to roasting under oxidizing atmosphere at a temperature of about 550 °C and leaching in dilute sulphuric acid to dissolve molybdenum, vanadium, nickel and part of aluminium. Metals from the leach solution were separated by solvent extraction. Both molybdenum and vanadium were selectively extracted with a suitable organic solvent leaving nickel and dissolved aluminium in the raffinate. Various parameters such as initial pH of the aqueous feed, organic to aqueous ratio (O:A), solvent concentration etc. were optimized for the complete extraction and recovery of Mo and V. Molybdenum and vanadium from the loaded organic were stripped by ammonia solution. They were recovered as their corresponding ammonium salt by selective precipitation, and were further calcined to get the corresponding oxides in pure form.

  9. Engineering Porous Poly(lactic acid Scaffolds with High Mechanical Performance via a Solid State Extrusion/Porogen Leaching Approach

    Directory of Open Access Journals (Sweden)

    Hua-Mo Yin

    2016-05-01

    Full Text Available A knotty issue concerning the poor mechanical properties exists in the porogen leaching approach to porous scaffolds, despite its advantage in tuning pore structure. To address this hurdle, solid state extrusion (SSE combined with porogen leaching was utilized to engineer porous scaffolds of poly(lactic acid (PLA. Advances introduced by poly(ethylene glycol (PEG caused the PLA ductile to be processed and, on the other hand, enabled the formation of interconnected pores. Thus, a well-interconnected porous architecture with high connectivity exceeding 97% and elevated porosity over 60% was obtained in the as-prepared PLA scaffolds with the composition of NaCl higher than 75.00 wt % and PEG beyond 1.25 wt %. More strikingly, the pore walls of macropores encompassed countless micropores and rough surface topography, in favor of transporting nutrients and metabolites as well as cell attachment. The prominent compressive modulus of the PLA scaffolds was in the range of 85.7–207.4 MPa, matching the normal modulus of human trabecular bone (50–250 MPa. By means of alkaline modification to improve hydrophilicity, biocompatible porous PLA scaffolds exhibited good cell attachment. These results suggest that the SSE/porogen leaching approach provides an eligible clue for fabricating porous scaffolds with high mechanical performance for use as artificial extracellular matrices.

  10. 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.

  11. 铜阳极泥碱性加压氧化浸出渣的硫酸浸出过程%Sulfuric acid leaching of residue from copper anode slime pretreated by alkaline oxidative pressure leaching

    Institute of Scientific and Technical Information of China (English)

    刘伟锋; 刘又年; 杨天足; 陈霖; 张杜超; 王安

    2013-01-01

    The process of sulfuric acid leaching was adopted to treat the residue from copper anode slime pretreated by alkaline pressure oxidation leaching.The effects of many factors such as sulfuric acid concentration,temperature,time,liquid-solid ratio,stirring speed and oxidation type in sulfuric acid leaching on residue yield and leaching ratio were investigated.The results show that leaching ratios of copper,tellurium and silver increase with the increase of the concentration of sulfuric acid,especially for the leaching ratio of silver.The phase of undissolved copper in the leaching residue exists mainly in the elemental,and the leaching ratio of copper can be enhanced with air.The optimum conditions of sulfuric acid leaching are determined.Under the optimum conditions of the sulfuric acid concentration 2.7 mol/L,temperature 85 ℃,liquid-solid ratio 5∶1,time 2 h,stirring speed 300 r/min and air pressure 0.1~0.2 MPa,the residue yield is 60%.The leaching rates of copper,tellurium,silver and nickel are 97.65%,77.53%,8.95% and 5.85%,respectively.%针对铜阳极泥碱性加压氧化浸出渣开展硫酸浸出过程研究,考察硫酸浓度、温度、时间、液固比、搅拌速度和氧化方式等因素对浸出渣渣率和金属浸出率的影响.研究结果表明:金属浸出率随硫酸浓度的增加而提高,银的溶解尤为明显;硫酸浸出渣中未溶解的铜主要以单质存在,采用空气氧化方式可以提高铜的浸出率;在最佳条件即硫酸浓度为2.7 mol/L,温度为85℃,液固比为5∶1,时间为2h,空气压力为0.1~0.2 MPa和搅拌速度为300 r/min下,硫酸浸出渣率为60.0%,Cu和Te的浸出率分别为97.65%和77.53%,Ag和Sb的浸出率分别为8.95%和2.0%.

  12. 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

  13. 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...

  14. Recovery of metals from waste printed circuit boards by supercritical water pre-treatment combined with acid leaching process.

    Science.gov (United States)

    Xiu, Fu-Rong; Qi, Yingying; Zhang, Fu-Shen

    2013-05-01

    Waste printed circuit boards (PCBs) contain a large number of metals such as Cu, Sn, Pb, Cd, Cr, Zn, and Mn. In this work, an efficient and environmentally friendly process for metals recovery from waste PCBs by supercritical water (SCW) pre-treatment combined with acid leaching was developed. In the proposed process, waste PCBs were pre-treated by SCW, then the separated solid phase product with concentrated metals was subjected to an acid leaching process for metals recovery. The effect of SCW pre-treatment on the recovery of different metals from waste PCBs was investigated. Two methods of SCW pre-treatment were studied: supercritical water oxidation (SCWO) and supercritical water depolymerization (SCWD). Experimental results indicated that SCWO and SCWD pre-treatment had significant effect on the recovery of different metals. SCWO pre-treatment was highly efficient for enhancing the recovery of Cu and Pb, and the recovery efficiency increased significantly with increasing pre-treatment temperature. The recovery efficiency of Cu and Pb for SCWO pre-treatment at 420°C was 99.8% and 80%, respectively, whereas most of the Sn and Cr were immobilized in the residue. The recovery of all studied metals was enhanced by SCWD pre-treatment and increased along with pre-treatment temperature. Up to 90% of Sn, Zn, Cr, Cd, and Mn could be recovered for SCWD pre-treatment at 440°C.

  15. 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.

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

    Institute of Scientific and Technical Information of China (English)

    刘大学; 王云; 袁朝新; 郭持皓; 李云; 孙聪

    2013-01-01

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

  17. 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.

  18. Selectively leaching Cu(Ⅱ) and Ni(Ⅱ) from acid mine drainage sludge by using ethylenediamine-ammonium sulfate

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    A method based on controlling the complexation-precipitation equilibrium of metal ions was proposed to selectively recover nickel and copper from hydroxide sludge formed by lime neutralization of acid mine drainage(AMD). Ethylenediamine(EDA) and ammonium sulfate were chosen as complex reagent and precipitating reagent, respectively, to dissolve target metal hydroxides from sludge and limit useless metal ions in the pregnant solution. Results from both synthetic and natural samples show the excellent selectivity for the target metals(copper and nickel) against Fe(Ⅲ), Ca(Ⅱ) and Mg(Ⅱ), 99% recovery of Cu(Ⅱ) and Ni(Ⅱ) and shorter leaching time can be reached by this process, and the resultant solution can be used for direct electrowinning. The optimum operating conditions are: pH=9~11, ρ(EDA)=40g/L, ammonium sulfate 50g/L, leaching time 5h(for natural sample) and 2.5h(for synthetic sludge), liquid to solid ratio being 4 with mechanical stirring at room temperature.

  19. 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.

  20. Relationship between Photocatalytic Activity and Ti{sup 3+} Defects in Acid-Leached Titanium Dioxide / Hydroxyapatite Composite

    Energy Technology Data Exchange (ETDEWEB)

    Ono, Y; Rachi, T; Okuda, T; Yokouchi, M; Kamimoto, Y [Mechanical and Material Engineering Division, Kanagawa Industrial Technology Center, 705-1 Shimo-imaizumi, Ebina, Kanagawa 243-0435 (Japan); Nakajima, A [Department of Metallurgy and Ceramics Science, Tokyo Institute of Technology, 2-12-1 O-okayama, Meguro-ku, Tokyo 152-8552 (Japan); Okada, K, E-mail: ono-y@kanagawa-iri.go.jp [Materials and Structures Laboratory, Tokyo Institute of Technology, 4259 Nagatsuda, Midori-ku, Yokohama 226-8503 (Japan)

    2011-10-29

    Effect of Ti{sup 3+} defect density on the photocatalytic activity was investigated using electron spin resonance (ESR) spectroscopy under UV irradiation at 103K. The Ti{sup 3+} signal intensity decreased with increasing heating temperature for the TiO{sub 2} powders prepared by hydroxyapatite (HAp) precipitation, heating and acid leaching process. The Ti{sup 3+} defect density of the TiO{sub 2} powder heat-treated at 700 deg. C was found to be about half that of the starting material, P25, without anatase-to-rutile phase transformation based on the results of X-ray diffraction. The photocatalytic activity of the TiO{sub 2} powder determined from the change of methylene blue concentration under UV irradiation became higher with decreasing of the Ti{sup 3+} defects without a significant change in the anatase ratio and specific surface area during the heat treatment.

  1. 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.

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

    Science.gov (United States)

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

    2015-11-01

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

  3. [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. 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.

  5. 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.

  6. Abscisic Acid Receptors: Past, Present and Future

    Institute of Scientific and Technical Information of China (English)

    Jianjun Guo; Xiaohan Yang; David J. Weston; Jin-Gui Chen

    2011-01-01

    Abscisic acid (ABA) is the key plant stress hormone. Consistent with the earlier studies in support of the presence of both membrane- and cytoplasm-localized ABA receptors, recent studies have identified multiple ABA receptors located in various subcellular locations. These include a chloroplast envelope-localized receptor (the H subunit of Chloroplast Mg2+-chelatase/ABA Receptor), two plasma membrane-localized receptors (G-protein Coupled Receptor 2 and GPCR-type G proteins),and one cytosol/nucleus-localized Pyrabactin Resistant (PYR)/PYR-Like (PYL)/Regulatory Component of ABA Receptor 1 (RCAR). Although the downstream molecular events for most of the identified ABA receptors are currently unknown, one of them, PYR/PYL/RCAR was found to directly bind and regulate the activity of a long-known central regulator of ABA signaling, the A-group protein phosphatase 2C (PP2C). Together with the Sucrose Non-fermentation Kinase Subfamily 2 (SnRK2s) protein kinases, a central signaling complex (ABA-PYR-PP2Cs-SnRK2s) that is responsible for ABA signal perception and transduction is supported by abundant genetic, physiological, biochemical and structural evidence. The identification of multiple ABA receptors has advanced our understanding of ABA signal perception and transduction while adding an extra layer of complexity.

  7. Proceedings of the 11. Annual British Columbia MEND Metal Leaching and Acid Rock Drainage (ML/ARD) Workshop : Performance of Dry Covers

    Energy Technology Data Exchange (ETDEWEB)

    Price, B. [Natural Resources Canada, Smithers, BC (Canada); Tremblay, G. [Natural Resources Canada, Ottawa, ON (Canada). Mine Environment Neutral Drainage Program; Bellefontaine, K. [British Columbia Ministry of Energy and Mines, Victoria, BC (Canada)] (eds.)

    2005-03-01

    Metal leaching and acid rock drainage (ML/ARD) are considered to be the largest environmental challenge facing the mining industry. This Mine Environment Neutral Drainage (MEND) workshop focused on the development and application of new technologies to prevent and control acid mine drainage. Significant progress has been made with an objective for new mines to open without long-term consequences of acid drainage upon closure. The mining industry now has access to a range of options to address this issue, including the application of dry covers. The theme of this workshop was the performance of dry covers. The topics of discussion ranged from the design requirements of dry covers, evaluation of the long-term performance of dry cover systems, soil covers in the Canadian north, dry cover projects in Sweden, field scale hydrology of dry covers, dry cover systems at open pit mines, the application of alternative covers for potash mining, and soil covers on waste rock and tailings. The importance of watershed, the major building block of landscapes, was also emphasized. The conference featured 20 presentations, of which 1 has been catalogued separately for inclusion in this database. refs., tabs., figs.

  8. 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)

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

    Institute of Scientific and Technical Information of China (English)

    李瑞迪; 袁铁锤; 范文博; 邱子力; 苏文俊; 钟楠骞

    2014-01-01

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

  10. 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.

  11. 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.

  12. Effect of Thermal Treatment and Acid Leaching Process on Pore Characteristics of Nanometer Porous Glass

    Institute of Scientific and Technical Information of China (English)

    HAN Jianjun; XU Feng; LIU Jiandang; ZHAO Xiujian

    2007-01-01

    Porous glass was prepared by thermally treating sodium borosilicate glass for different time,the effect of thermal treatment on pore size distribution was discussed and the pore size of the prepared porous glass was measured by scanning electron microscopy (SEM) and differential thermal analysis (DTA). The results show that the optimum porous glass with an average diameter of 80 nm can be prepared by thermal treatment at 600 ℃ for 12 h and then acid treatment for 12 h in 2 mol· L-1 hydrochloric acid solution.

  13. 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.

  14. 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%.

  15. 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

  16. Fundamental tests on recovery of valuable matters from coal ash. II. ; Direct hydrofluoric acid leach process. Sekitanbaichu no yukabutsu kaishu kiso shiken (dai 4 kai). II. ; Chokusetsu fussan chushutsuho

    Energy Technology Data Exchange (ETDEWEB)

    Kumamoto, J. (Kobe Steel, Ltd., Kobe (Japan))

    1990-08-01

    As a recovery method of valuable content in fly ash upon the chemical treatment, study was made of direct hydrofluoric acid leach process which is an acid leach method to use mixed acid of fluoric acid and hydrochloric acid. In order to study the purpose of use of dissolution residue and recovered matter, based on the result of test and research, so far made, test was made on synthesis of silicon carbide and produced condition of micro-granular SiO{sub 2}, and both technical and economic evaluations were further done of practical use plant. At 3 to 4 in mole C/SiO{sub 2} ratio, silicon carbide being produced with a good synthetic ratio, residue was indicated to give a possibility of being effectively utilized. In order to micro-granulate SiO{sub 2} grain, it is effective to lower the concentration of Si in the solution or heighten the temperature of solution. In each of both the cases, obtainment was made of micro-granular grain, 0.01 to 0.04 microns in size. As a result of evaluating the practical use plant in economicality, profitability was not indicated to be good against the product price, calculated from the present market scale of silica. 3 refs., 11 figs.

  17. 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.

  18. 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.

  19. Trends in nitrogen deposition and leaching in acid-sensitive streams in Europe

    Directory of Open Access Journals (Sweden)

    R. F. Wright

    2001-01-01

    Full Text Available Long-term records of nitrogen in deposition and streamwater were analysed at 30 sites covering major acid sensitive regions in Europe. Large regions of Europe have received high inputs of inorganic nitrogen for the past 20 - 30 years, with an approximate 20% decline in central and northern Europe during the late 1990s. Nitrate concentrations in streamwaters are related to the amount of N deposition. All sites with less than 10 kgN ha-1 yr-1 deposition have low concentrations of nitrate in streamwater, whereas all sites receiving > 25 kgN ha-1 yr-1 have elevated concentrations. Very few of the sites exhibit significant trends in nitrate concentrations; similar analyses on other datasets also show few significant trends. Nitrogen saturation is thus a process requiring many decades, at least at levels of N deposition typical for Europe. Declines in nitrate concentrations at a few sites may reflect recent declines in N deposition. The overall lack of significant trends in nitrate concentrations in streams in Europe may be the result of two opposing factors. Continued high deposition of nitrogen (above the 10 kgN ha-1 yr-1 threshold should tend to increase N saturation and give increased nitrate concentrations in run-off, whereas the decline in N deposition over the past 5 – 10 years in large parts of Europe should give decreased nitrate concentrations in run-off. Short and long-term variations in climate affect nitrate concentrations in streamwater and, thus, contribute "noise" which masks long-term trends. Empirical data for geographic pattern and long-term trends in response of surface waters to changes in N deposition set the premises for predicting future contributions of nitrate to acidification of soils and surface waters. Quantification of processes governing nitrogen retention and loss in semi-natural terrestrial ecosystems is a scientific challenge of increasing importance. Keywords: Europe, acid deposition, nitrogen, saturation, recovery

  20. 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.

  1. 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].

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

    Institute of Scientific and Technical Information of China (English)

    梁铎强; 王吉坤; 汪云华

    2008-01-01

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

  3. A hydrometallurgical process for the recovery of terbium from fluorescent lamps: Experimental design, optimization of acid leaching process and process analysis.

    Science.gov (United States)

    Innocenzi, Valentina; Ippolito, Nicolò Maria; De Michelis, Ida; Medici, Franco; Vegliò, Francesco

    2016-12-15

    Terbium and rare earths recovery from fluorescent powders of exhausted lamps by acid leaching with hydrochloric acid was the objective of this study. In order to investigate the factors affecting leaching a series of experiments was performed in according to a full factorial plan with four variables and two levels (4(2)). The factors studied were temperature, concentration of acid, pulp density and leaching time. Experimental conditions of terbium dissolution were optimized by statistical analysis. The results showed that temperature and pulp density were significant with a positive and negative effect, respectively. The empirical mathematical model deducted by experimental data demonstrated that terbium content was completely dissolved under the following conditions: 90 °C, 2 M hydrochloric acid and 5% of pulp density; while when the pulp density was 15% an extraction of 83% could be obtained at 90 °C and 5 M hydrochloric acid. Finally a flow sheet for the recovery of rare earth elements was proposed. The process was tested and simulated by commercial software for the chemical processes. The mass balance of the process was calculated: from 1 ton of initial powder it was possible to obtain around 160 kg of a concentrate of rare earths having a purity of 99%. The main rare earths elements in the final product was yttrium oxide (86.43%) following by cerium oxide (4.11%), lanthanum oxide (3.18%), europium oxide (3.08%) and terbium oxide (2.20%). The estimated total recovery of the rare earths elements was around 70% for yttrium and europium and 80% for the other rare earths.

  4. A mathematical model for isothermal heap and column leaching

    Directory of Open Access Journals (Sweden)

    Lima L.R.P. de Andrade

    2004-01-01

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

  5. 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

  6. Leaching From Biomass Gasification Residues

    DEFF Research Database (Denmark)

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

    2011-01-01

    The aim of the present work is to attain an overall characterization of solid residues from biomass gasification. Besides the determination of chemical and physical properties, the work was focused on the study of leaching behaviour. Compliance and pH-dependence leaching tests coupled with geoche...

  7. 硫酸酸浸法除磷石膏中杂质氟的研究%Removing impurity fluorine from phosphogypsum by sulfuric acid leaching method

    Institute of Scientific and Technical Information of China (English)

    孔霞; 罗康碧; 李沪萍; 韩青; 苏毅

    2012-01-01

    Phosphogypsum heat was leached with H2SO4 as leaching agent, and the removal of fluoride impurity in the phosphogypsum was studied to provide the basic data for the comprehensive utilization of the phosphogypsum. Based on the uniform design experiment, the effects of temperature, time, mass fraction of sulfuric acid, solid mass content, particle size of five factors on the removal rate of impurity fluorine were further researched. The results show that temperature, time, mass fraction of sulfuric acid are the main factors affecting the fluorine removal rate, but solid mass concentration and particle size have smaller effect on the results. The ideal conditions of removing fluorine are as follows; leaching temperature 88 ℃ , leaching time 45 min, mass fraction of H2SO4 30% , solid mass concentration 0.43 g/mL. Under the optimized experimental conditions, the removal rate of impurity fluorine can reach 84. 50%, and the fluorine content in the phosphogypsum processed is only 0. 036%. Processing the phosphogypsum with the sulfuric acid leaching method has good removal effect of the impurity fluoride, and improves the whiteness of phosphogypsum purified.%以H2SO4为浸取剂对磷石膏进行热浸取,考察磷石膏中杂质氟的去除情况,为磷石膏综合利用提供基础数据.研究在均匀设计实验的基础上,迸一步考察了温度、时间、硫酸质量分数、含固量(质量浓度)、粒度5个因素对杂质氟去除率的影响规律.结果表明:温度、时间、硫酸是影响氟去除率的主要因素,而含固量、粒度对结果影响较小.较理想的除氟条件为浸取温度88℃,浸取时间45 min,H2SO4质量分数30%,含固量0.43 g/mL,在优化实验条件下杂质氟的去除率可以达到84.50%,处理后的磷石膏含氟仅为0.036%.采用硫酸酸浸处理磷石膏,杂质氟去除效果好,且提高了净化磷石膏的白度.

  8. 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.

  9. 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

  10. 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).

  11. 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.

  12. Preparation and characterization of TiO2/acid leached serpentinite tailings composites and their photocatalytic reduction of chromium(VI).

    Science.gov (United States)

    Sun, Zhiming; Zheng, Liming; Zheng, Shuilin; Frost, Ray L

    2013-08-15

    Composite TiO2/acid leached serpentine tailings (AST) were synthesized through the hydrolysis-deposition method and characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectrometry (EDS), Fourier-transform infrared spectroscopy (FT-IR), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and surface area measurement (BET). The XRD analysis showed that TiO2 coated on the surface of acid leached serpentine tailings was mixed crystal phases of rutile and anatase, the grain size of which is 10-30 nm. SEM, TEM, and EDS analysis exhibited that nano-TiO2 particles were deposited on the surface and internal cavities of acid leaching serpentine tailings. The XPS and FT-IR analysis demonstrated that the coating process of TiO2 on AST was a physical adsorption process. The large specific surface area, porous structure, and plentiful surface hydroxyl group of TiO2/AST composite resulted in the high adsorption capacity of Cr(VI). The experimental results demonstrated that initial concentration of Cr(VI), the amount of the catalyst, and pH greatly influenced the removal efficiency of Cr(VI). The removal kinetics of Cr(VI) at a relative low initial concentration was fitted well with Langmuir-Hinshelwood kinetics model with R(2) value of about unity. The as-prepared composites exhibited strong adsorption and photocatalytic capacity for the removal of Cr(VI), and the possible photocatalytic reduction mechanism was studied. The photodecomposition of Cr(VI) was as high as 95% within 2h, and the reusability of the photocatalysis was proven.

  13. 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.

  14. Acid rock drainage and metal leaching from mine waste material (tailings) of a Pb-Zn-Ag skarn deposit: environmental assessment through static and kinetic laboratory tests

    OpenAIRE

    Blanca Adriana Méndez Ortiz; Alejandro Carrillo Chávez; Marcos Gustavo Monroy Fernández

    2007-01-01

    In this work, the processes and products involved in the generation of acid rock drainage – metal leaching (ARD-ML) from mine waste material (tailings) derived from the exploitation of an ore type Pb- Zn-Ag skarn were characterized. Laboratory tests (static and kinetic) of historic and recent tailings were conducted along with the mineralogical characterization of solids, and chemical analyses of solids and leachates. Pyrite (FeS2) is the most abundant sulfi de phase, and one of the main mine...

  15. Zinc leaching from tire crumb rubber.

    Science.gov (United States)

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

    2012-12-04

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

  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. Recovery Silver From Silver-containing Acid Leaching Solution%从含银酸浸液中回收银的试验研究

    Institute of Scientific and Technical Information of China (English)

    胡良辉; 曾斌; 余攀; 毛永星

    2014-01-01

    研究了从某含银酸浸液中回收银,考察了沉银试剂类型及加入量、反应温度、体系pH、反应时间对银回收率的影响,确定了较优工艺参数。试验结果表明,在饱和亚硫酸钠溶液用量为15%、反应温度为70℃、体系p H为2.0、反应时间9 h条件下,银回收率为98.14%。%Recovery silver from a silver-containing acid leaching solution has been researched .The effects of precipitation agent and its dosage ,reaction temperature ,system pH and reaction time on recovery rate of silver were examined .The optimal conditions were determined .The results show that under the conditions of saturated sodium sulfite solution accounting for the acid leaching solution volume of 15% ,reaction temperature of 70 ℃ ,system pH of 2 .0 and reaction time of 9 hours ,the recovery rate of silver is 98 .14% .

  18. 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.

  19. 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.

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

    Science.gov (United States)

    Rothwell, James J; Futter, Martyn N; Dise, Nancy B

    2008-11-01

    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 (15kg N ha(-1) year(-1)) at 215 sites across Europe. The analysis identified throughfall NO(3)(-) 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.

  1. Germanium separation and purification by leaching and precipitation

    Institute of Scientific and Technical Information of China (English)

    Saeid Bayat; Sajjad Aghazadeh; Mohammad Noaparast; Mahdi Gharabaghi; Behrooz Taheri

    2016-01-01

    In this research work, extraction and purification of germanium from zinc leach residues (ZLR) were investigated. The results of ICP, XRF, and atomic adsorption spectroscopy (AAS) tests show that contents of germanium, iron, lead, and zinc within the leaching residue were 105×10−6, 3.53%, 10.35%, and 8.8%, respectively. XRD results indicate that the main minerals were in different forms of sulfates (CaSO4·2H2O, PbSO4 and ZnSO4·6H2O), silicate (SiO2), and oxide (Fe2O3). Dissolution of leaching filter cake was carried out using 5 parameters and each in 4 levels (acid concentration, temperature, time, liquid-to-solid ratio, and stirring speed) by Taguchi method (L16), and then optimization of the effective parameters by response surface method. Under optimum conditions, zinc and germanium dissolution efficiencies were 88.71% and 8%, respectively. Leaching tests with sulfuric acid (added di-ammonium oxalate monohydrate) and hydrochloric acid (HCl) on the residues obtained from previous-stage sulfuric acid dissolution, yielded germanium and iron recoveries of 83%, 88%, 40%, and 90%, respectively. Thus, leaching experiment with sulfuric acid (added di-ammonium oxalate monohydrate) was superior to that with hydrochloric acid due to high and low extraction amounts of germanium and iron, respectively. Precipitation experiments revealed that germanium purification with tannic acid presented a better result compared to sodium hydroxide and ammonia. Under optimum conditions, contents of germanium and iron in the solution after precipitation were 0.1505% and 14.7% with precipitation yields of 91% and 52%, respectively.

  2. Experiments on Molybdemm Acid Leaching of a Refractory Molybdemm Ore in Hebei%河北某难选钼矿石酸浸浸钼试验

    Institute of Scientific and Technical Information of China (English)

    康维刚; 郭鹏志; 邱沙; 彭志兵

    2015-01-01

    河北某难选钼矿石氧化程度较高,氧化钼占总钼的52.54%,主要以钼华、钼钙矿和钼铅矿等形式存在;硫化钼矿物主要为非晶质或隐晶质胶硫钼矿,多以胶状集合体产出,单体解离困难,可浮性较差。为高效开发利用该钼矿资源,进行了酸浸工艺条件研究。结果表明,100 g粒度为-2 mm的试样中加入30 g浓硫酸,在液固比为1.5 mL/g、浸出温度为90℃、搅拌器转速为250 r/min情况下浸出3 h,钼浸出率达86.19%。因此,硫酸酸浸工艺是该资源的高效开发利用工艺。%There is a refractory molybdenum ore in Hebei with high oxidation degree,and molybdenum oxide accounts for 52. 54% of total molybdenum,and mainly exits in form of molybdite,powethite,wulfenite etc.;Molybdenum sulfide mineral is mainly amorphous or cryptocrystalline jordisite,and most exists in colloidal aggregates. With poor floatability,it belongs to re-fractory molybdenum ore. For the efficient development and utilization of the molybdenum resource,study on the process of acid leaching conditions was conducted. The results show that,under conditions of 30 g concentrated sulfuric acid added into 100 g samples with the particle size of 2~0 mm,liquid-solid ratio of 1. 5 mL/g,mixing speed at 250 r/min,leaching temperature at 90 ℃ for 3 h,molybdenum extraction rate reached 86. 19%. Therefore,sulfuric acid leaching is the efficient development and utilization process for the resources.

  3. 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%.

  4. 硝酸浸出失效催化剂提取银的实验研究%Experimental Study on Extracting Silver by Leaching Spent Catalyst with Nitric Acid

    Institute of Scientific and Technical Information of China (English)

    范兴祥; 董海刚; 吴跃东; 付光强; 刘杨; 赵家春; 吴晓峰; 昝林寒; 李博捷

    2013-01-01

    采用硝酸浸出失效催化剂提取其中金属银,研究了失效催化剂粒度、硝酸用量、浸出温度、浸出时间和洗涤次数等因素对银浸出率的影响.结果表明,失效催化剂粒度对银浸出率影响显著,增加洗涤次数有利于提高银的浸出率.通过实验,确定了合理的工艺参数为:硝酸用量为失效催化剂质量的70%、浸出温度65℃、浸出时间3h、催化剂粒度为0.125 ~0.18 mm、搅拌洗涤3次.在此条件下,银的浸出率为99.52%,浸出渣含银0.072%.综合实验结果表明,从失效催化剂到海绵银产品,银的直收率达到99.27%.%Spent catalyst was leached by nitric acid to extract metallic silver from it. The effects of the particle size of spent catalyst, the dosage of nitric acid, leaching temperature, leaching time and washing times on the leaching rate of silver were investigated. The results showed that the particle size of spent catalyst has great effect on the leaching rate of silver which would also be improved by increasing washing times. Based on experiments, technological parameters are reasonably determined as follows; the dosage of nitric acid was 70% of the quality of spent catalyst, the leaching temperature was set at 65 ℃, leaching time was 3 h, the particle size was 0.125 ~0.18 mm, the washing times were 3. Under these conditions, the leaching rate of silver was 99.52% and the content of silver in the leaching residues was 0.072%. The comprehensive experiment showed that spent catalyst can be transferred to sponge silver products with this process with direct recovery rate of silver reaching 99.27%.

  5. 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.

  6. 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%.

  7. 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

  8. Using pyrolytic acid leaching as a pretreatment step in a biomass fast pyrolysis plant: process design and economic evaluation

    NARCIS (Netherlands)

    Oudenhoven, S.R.G; Ham, van der A.G.J.; Berg, van den H.; Westerhof, R.J.M.; Kersten, S.R.A.

    2016-01-01

    Removing alkali and alkaline earth metals (AAEMs) from biomass, with pyrolytic acids, before pyrolysis leads to increased organic oil and sugar yields. These pyrolytic acids are produced and concentrated within the pyrolysis process itself. The purpose of this paper was to evaluate under which condi

  9. Zinc Hydrometallurgy Process Optimization With Acid Leaching-Jarosite Precipitation%酸浸出-沉矾湿法炼锌工业优化实践∗

    Institute of Scientific and Technical Information of China (English)

    曾淑琴; 曾桂忠; 赵贺永

    2016-01-01

    分析内蒙古赤峰某锌冶炼厂酸浸出-沉矾工艺中沉矾渣、高酸渣渣锌偏高以及沉矾后液铁含量偏高的问题。通过采用相应的技改优化措施,不仅降低了沉矾渣与高酸渣的锌含量,同时通过调整辅料加入方式,使沉矾分梯度进行,也降低了除铁后液铁浓度,减少了辅料用量,优化措施实施后产生了可观的经济效益。%The problems of high zinc contents in the jarosite precipitation slag and high⁃acid slag, in the acid⁃leaching and jarosite⁃precipitation process in a zinc smelter in Chifeng city, Inner Mongolia were analyzed. By the adoption of respective improvement measures, the zinc contents in the jarosite precipitation slag and high⁃acid slag was reduced. Meanwhile, by adjusting the feeding way of the supplementary materials to make jarosite precipitation gradiently, the iron concentration liq⁃uid after iron removal was reduced with reduction of supplementary materials consumption. Significant profit has been a⁃chieved after the implementation of the optimization measures.

  10. Two-Stage Separation of V(IV) and Al(III) by Crystallization and Solvent Extraction from Aluminum-Rich Sulfuric Acid Leaching Solution of Stone Coal

    Science.gov (United States)

    Shi, Qihua; Zhang, Yimin; Liu, Tao; Huang, Jing; Liu, Hong

    2016-12-01

    To improve separation of V(IV) and Al(III) from aluminum-rich sulfuric acid leaching solution of stone coal, the two-stage separation by crystallization and solvent extraction methods have been developed. A co-extraction coefficient (k) was put forward to evaluate comprehensively co-extraction extent in different solutions. In the crystallization stage, 68.2% of aluminum can be removed from the solution. In the solvent extraction stage, vanadium was selectively extracted using di-2-ethylhexyl phosphoric acid/tri-n-butyl phosphate from the crystalline mother solution, followed by H2SO4 stripped efficiently. A V2O5 product with purity of 98.39% and only 0.10% Al was obtained after oxidation, precipitation, and calcination. Compared with vanadium extraction from solution without crystallization, the counter-current extraction stage of vanadium can be decreased from 6 to 3 and co-extraction coefficient (k) decreased from 2.51 to 0.58 with two-stage separation. It is suggested that the aluminum removal by crystallization can evidently weaken the influence of aluminum co-extraction on vanadium extraction and improve the selectivity of solvent extraction for vanadium.

  11. Concentration of Nickel from a High Magnesium Iron Lean Nickel Laterite Ore by Acid Leaching%从某高镁铁贫红土镍矿中酸浸富集镍试验

    Institute of Scientific and Technical Information of China (English)

    王宇斌; 彭祥玉; 张小波; 李帅; 卫亚儒

    2015-01-01

    某难选贫氧化镍矿中铁和氧化镁含量较高,镍品位仅为0.71%,物理方法难以选别。研究采用碎磨—酸浸—净化—硫化沉镍—碳化沉镁的工艺,考察了矿石粒度、浸出时间、浸出剂用量、浸出温度以及液固比等因素对镍浸出率的影响。结果表明:在矿石粒度为-0.35 mm占60%,浸出时间为2 h,硫酸+盐酸的用量为50+200 g/L,浸出温度为70℃,液固比为4:1的最佳条件下,镍的浸出率达到87.29%。研究结果对该类矿石中镍的回收有一定的参考意义。%The contents of iron and magnesium in a refractory depleted nickel oxide ore are high, while the content of nickel is only 0.71%, so it is difficult to separate the ore by physical methods. The effects of experimental conditions such as ore particle size, leaching time, leaching agent dos-age, leaching temperature and liquid-solid ratio on nickel leaching rate were investigated with comminution-acid leaching-purification-nickel sulfide precipitation-magnesium carbide pre-cipitation process.Under the condition of ore particle size -0.35 mm of 60%, leaching time 2 h, the amount of sulfuric acid and hydrochloric of 50+200 g/L, leaching temperature 70℃, liquid-solid ratio of 4:1, the leaching rate was 87.29%.The research reslut has some reference value on this kind of ore in recovery of nickel.

  12. 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

  13. 含铜难处理金精矿焙烧-酸浸-氰化提金工艺研究%Roasting-acid Leaching-cyanidation of Refractory Gold Concentrate Containing Copper

    Institute of Scientific and Technical Information of China (English)

    衷水平

    2013-01-01

    Focusing on refractory gold concentrate containing copper,the technology of roasting-acid leaching-cyanidation was studied and the optimized condition was obtained.Experimentation results show that Cu leaching rate is above 95% and copper grade of acid-leach residue is low of 0.3% when concentrate roasted 2 hours at temperature of 540 ℃,roasted product is leached with sulfuric acid of 30 g/L under conditions of 3 of liquid-solid ratio,90 ℃ of temperature and time of 1.5 hours.The recovery rate of Au is above 96% when decoppering slag is leached with the densities of sodium cyanide of 4‰under conditions of 30%of pulp density and time of 24 hours. This process realizes recovery Au and Cu in high efficiency.%  针对某含铜难处理金精矿,研究了焙烧—酸浸—氰化提金工艺,获得了优化工艺条件。结果表明,在焙烧温度为540℃,焙烧时间2 h,焙砂在初酸浓度为30 g/L、液固比3∶1,浸出温度90℃,浸出时间1.5 h的条件下,Cu浸出率>95%,酸浸渣铜品位可降至0.3%以下;脱铜渣在NaCN浓度为4‰、矿浆浓度为30%,氰化时间24 h的条件下,Au浸出率达96%以上,实现了Au和Cu的高效回收。

  14. Processing of Gold-containing Slag from Sulfuric Acid Production Using Sulfatizing Roasting Followed by Chlorine Leaching%含金硫酸渣硫酸盐化焙烧-氯化浸金研究

    Institute of Scientific and Technical Information of China (English)

    尤大海; 张亚辉; 隆岗; 涂博; 黄俊玮

    2014-01-01

    针对难处理含金硫酸渣进行了硫酸盐化焙烧-氯化(氯酸钠-氯盐)浸出试验研究,考察了氯酸钠用量、氯化钠用量、液固比、浸出时间、浸出温度、焙烧预处理等因素对金浸出率的影响。研究结果表明,在优化的试验条件:氯化钠用量为80 kg/t,氯酸钠100 kg/t,反应温度80℃,液固比为3,反应时间为4 h下,处理该含金硫酸渣可以得到91.44%的金浸出率。%Sulfatizing roasting and chlorine leaching of refractory gold-containing slag from sulfuric acid production have been investigated. The effects of sodium chlorate dosage, sodium chloride dosage, liquid-solid ratio, leaching time, reaction temperature and pretreatment condition on leaching recovery of gold have been studied. The results show that the leaching rate can reach as high as 91.44% under the optimum conditions that the addition of NaClO3 is 100 kg/t, the addition of NaCl is 80 kg/t, the liquid-solid ratio is 3, the leaching temperature is 80℃ and the leaching time is 4.0 h.

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

    Science.gov (United States)

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

    2016-03-01

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

  16. 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.

  17. 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.

  18. A technique for sequential leaching of coal and fly ash resulting in good recovery of trace elements.

    Science.gov (United States)

    Norris, Pauline; Chen, Chien-Wei; Pan, Wei-Ping

    2010-03-17

    Coal and fly ash contain many elements. These elements exist in different forms which may change throughout the coal combustion process. There are several processes, including X-ray techniques and leaching techniques by which studies have attempted to assess the form of a particular element in a sample. This work focuses on determining the leachability of selected elements sequentially leached in four extraction solutions: water, 1M ammonium acetate, 3M hydrochloric acid and 50% hydrofluoric acid. The emphasis is on evaluating the steps involved in the leaching process with the mass recovery for each element being the basis for evaluation. The total amount of each element that will leach out under the given extraction condition is presented as a fraction of the total present in the material. The materials evaluated were NIST coal and fly ash standards. The elements measured in this study include aluminum, barium, beryllium, calcium, chromium, cobalt, iron, magnesium, manganese, nickel, potassium, sodium, strontium, vanadium and zinc.

  19. Recovering Silver from Acid-Leaching Residues of Zinc Ore by Flotation%湿法炼锌酸浸出渣浮选回收银试验

    Institute of Scientific and Technical Information of China (English)

    黄万抚; 钟祥熙

    2015-01-01

    传统锌精矿伴生银回收,均是从挥发窑渣中进行,由于矿物性质变化,导致银无法有效回收.进行了从锌酸浸出渣中浮恒回收银的研究,解决了锌精矿中伴生银回收的问题.某湿法炼锌浸出渣含Ag 350 g/t,Au<0.01 g/t,Pb 3.87%,Zn 17.45%,Cu 1.38%,银主要以自然银存在,占60.13%.采用高效捕收剂HT-1#、起泡剂HT-2#进行浮恒,经过一粗四精三扫工艺,获得银精矿产率4.39%,含银6616 g/t,银回收率82.98%,取得良好的经济技术指标.%In the traditional recycling of silver zinc smelting slag, most silver is recovered from rotary kiln slag. However, silver can not effectively be recovered, due to changes of the mineral properties. A process involving the recovery of silver directly from zinc-leached residues was developed. The residues after acid leaching of zinc contained Ag 350 g/t, Au<0.01 g/t, Pb 3.87%, Zn 17.45%, Cu 1.38%, and 60.13% of silver existing in the residues was natural silver state. By using HT-1# as a collector and HT-2# as a frother, and following a flowsheet of one roughing stage, four cleaning stages and three scavenging stages, the silver in the residues could be concentrated by about 20 times to a level of 6616 g/t with a recovery rate of 82.98%.

  20. 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.

  1. 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.

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

    Science.gov (United States)

    Petter, P M H; Veit, H M; Bernardes, A M

    2014-02-01

    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 2h at 60°C and 80°C. The leaching of Au with a commercial reagent (cyanide) and the Ag with HNO3were made. The leaching of Au and Ag with alternative reagents: Na2S2O3, and (NH4)2S2O3 in 0.1M concentration with the addition of CuSO4, NH4OH, and H2O2, 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 CuSO4 was added.

  3. Leaching of heavy metals from steelmaking slags

    Energy Technology Data Exchange (ETDEWEB)

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

    2006-07-01

    Leaching tests with EAF and Ladle slags were performed, using a flow through tests and the standard batch test DIN 38414-S4. The previous method was used to simulate the leaching behaviour of steel slags under landfill. the chemical analysis of the leachates during this period shows, in general, for both types of slag, and increase of heavy metal releases with ageing. Standard test method DIN 38414-S4 was used to evaluate leachability of heavy metals by water in unprocessed slags. After more than one year of trials, slang samples submitted to these trials presented very low total leaching levels. The most extracted elements are calcium and magnesium. Nevertheless, in flow-though test, calcium and magnesium leached from solid slags are below 0.5% and all other metals below 0.1%. Leachates obtained with DIN 38414-S4 present, as expected, higher leaching values; however, these are inferior to 5% (Ca) and 1% (other elements). (Author) 12 refs.

  4. 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.

  5. Recovery of gold, silver and copper from complex gold concentrate by roasting-acidic leaching-cyanidation process%焙烧-酸浸-氰化法从复杂金精矿中回收金银铜

    Institute of Scientific and Technical Information of China (English)

    吴在玖

    2013-01-01

      采用焙烧-酸浸-氰化工艺综合回收复杂金精矿中的金、银、铜.结果表明,焙烧温度、焙烧时间、焙烧添加剂种类和用量对金、银、铜浸出率影响显著.实验确定了较优工艺条件为:焙烧添加剂NaOH用量为6%,温度630℃,焙烧时间3 h,硫酸浓度1 mol/L,酸浸液固体积质量比5∶1,酸浸温度50℃,酸浸4 h,氰化纳浓度3‰,氰化浸出液固体积质量比5∶1,常温氰化72 h.在上述条件下,金、银、铜浸出率分别达到93.53%、75.37%、94.23%.%Gold, silver and copper were extracted from complex gold concentrate by roasting-acidic leaching-cyanidation process. The experimental results show that the roasting temperature, time, additive and its dosage have great influence on the leaching of gold, silver and copper. The optimal conditions were further determined as follows: NaOH dosage of 6 %(ω), roasting temperature of 630 °C, roasting time of 3 h, sulfuric acid concentration of 1 mol/L, liquid to solid ratio of 5∶1 in acidic leach, leaching temperature of 50 °C, leaching time of 4 h, sodium cyanide concentration of 3 ‰, liquid to solid ratio of 5∶1 in cyanidation, room temperature and cyanidation time of 72 h. Under above-mentioned conditions, the leaching rate of gold, silver and copper achieved at 93.53%, 75.37%and 94.23%respectively.

  6. 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

  7. Nitrate Leaching Management

    Science.gov (United States)

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

  8. Nitrate Leaching Index

    Science.gov (United States)

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

  9. 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.

  10. 酸性加压浸出液中钼的萃取分离%Molybdenum Solvent Extraction Technology From Acid Pressure Leaching Solution

    Institute of Scientific and Technical Information of China (English)

    邹小平; 张邦胜; 张磊; 王海北

    2014-01-01

    研究了从酸性加压浸出液中采用溶剂萃取法提取钼工艺,考察了萃取剂浓度、改质剂浓度、萃取相比、萃取时间等对钼萃取率的影响。试验结果表明,在有机相组成25%N235+5%异辛醇+磺化煤油,O/A=3/1,混合时间3 min的条件下,钼的萃取率可达到98%以上;负载有机相采用20%的氨水反萃,O/A=1/3,在两级逆流萃取的条件下钼反萃率超过98%。%The technology of extracting molybodenum from acid pressure leaching solution adopting solvent extraction method was researched. The effects of extractant concentration, modification agent concentration, phase ratio and extraction time on the extraction rate of Mo were investigated. The tests result showed that the extraction ratio of Mo could reach above 98% at the condition of the organic phase containing 20%N235, 5%Isooctanol and Kerosene with O/A of 1/3, and the mixing time of 3 min. When the loaded organic reagent was stripped with 20% ammonia, the stripping ratio of Mo was more than 98% after two-stage stripping with O/A of 3/1.

  11. 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.

  12. 氯化法回收废钯-氧化铝催化剂中的钯%Recovery of Palladium from Spent Pd-Al2O3 Catalyst by Hydrochloric Acid Leaching

    Institute of Scientific and Technical Information of China (English)

    李骞; 胡龙; 饶雪飞; 悟永斌; 徐斌; 姜涛

    2015-01-01

    惣悦化铝为载体的某含钯废催化剂为原料,采用恿酸介质中添加悦化助浸剂的方案对钯恒择性浸出,并考察了焙烧,还原,浸出过程的适惚工惤条件。结果表明,钯的回收率可惣达到98%惣上。%Palladium was recovered from spent alumina-supported catalyst by the process of selective leaching using hydrochloric acid with an oxidant. The optimized conditions of roasting, reduction, leaching processes were also investigated. The results showed that the palladium recovery ratio was over 98% in the optimum condition.

  13. Catalytic Role of Silver in Acid Pressure Oxidative Leaching of Sphalerite Concentrate%闪锌矿氧压酸浸过程中银的催化作用

    Institute of Scientific and Technical Information of China (English)

    梁铎强; 王吉坤; 汪云华

    2008-01-01

    An attempt was made to investigate the catalytic role of silver in enhancing the rate of acid pressure oxidative leaching of sphalerite concentrate.A series of batch experiments were performed under various conditions to investigate the influences of variables,such as temperature and duration.The experimental results obtained show that as a catalyst,aqueous silver ions can accelerate the leaching of sphalerite concentrates significantly.%进行了银对闪锌矿氧压酸浸催化作用的研究.通过间歇性小型试验考察了各种因素对浸出率的影响,诸如浸出温度、浸出时间.试验在2升的高压釜内进行,结果表明银离子对闪锌矿氧压酸浸有显著的催化作用.

  14. 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.

  15. 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

  16. 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

  17. 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.

  18. 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.

  19. Leaching capacity of metals-metalloids and recovery of valuable materials from waste LCDs.

    Science.gov (United States)

    Savvilotidou, Vasiliki; Hahladakis, John N; Gidarakos, Evangelos

    2015-11-01

    The purpose of Directive 2012/19/EU which is related to WEEE (Waste Electrical and Electronic Equipment), also known as "e-waste", is to contribute to their sustainable production and consumption that would most possibly be achieved by their recovery, recycling and reuse. Under this perspective, the present study focused on the recovery of valuable materials, metals and metalloids from LCDs (Liquid Crystal Displays). Indium (In), arsenic (As) and stibium (Sb) were selected to be examined for their Leaching Capacity (R) from waste LCDs. Indium was selected mainly due to its rarity and preciousness, As due to its high toxicity and wide use in LCDs and Sb due to its recent application as arsenic's replacement to improve the optimal clarity of a LCD screen. The experimental procedure included disassembly of screens along with removal and recovery of polarizers via thermal shock, cutting, pulverization and digestion of the shredded material and finally leaching evaluation of the aforementioned elements. Leaching tests were conducted under various temperatures, using various solid:liquid (S/L) ratios and solvents (acid mixtures), to determine the optimal conditions for obtaining the maximum leaching capacities. The examined elements exhibited different leaching behaviors, mainly due to the considerable diversity in their inherent characteristic properties. Indium demonstrated the highest recovery percentages (approximately 60%), while the recovery of As and Sb was unsuccessful, obtaining poor leaching percentages (0.16% and 0.5%, respectively).

  20. 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

  1. 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.

  2. 采用酸浸法从废旧锂离子电池中回收金属钴%The Recovery of Cobalt from the Spent Lithium-ion Batteries Using Acid Leaching Method

    Institute of Scientific and Technical Information of China (English)

    乔秀丽; 田军; 马松艳; 赵东江

    2011-01-01

    The metal cobalt in lithium-ion battery cathode material is recycled by hydrochloric acid-hydrogen peroxide, sulfuric acid-hydrogen peroxide and nitric acid-hydrogen peroxide as the leaching solution, respectively.The influences of concentration, temperature, amount of hydrogen peroxide, reaction time, solid-liquid ratio on leaching efficiency of cobalt ion are studied. Experimental results have shown that the hydrochloric acid-hydrogen peroxide system is the most appropriate leaching solution. The optimum process conditions are 4.0 mol/L of hydrochloric acid concentration, 5:1 of hydrochloric acid-hydrogen peroxide volume ratio, 61 min of reaction time,73℃of reaction temperature and 1:30.3 of solid-liquid ratio (g/mL). Under these conditions, leaching rate of cobalt ion is 99.8%.%分别采用盐酸-30%过氧化氢、硫酸-30%过氧化氢和硝酸-30%过氧化氢为浸取液,回收锂离子电池正极材料中的金属钴,研究了浓度、温度、30%过氧化氢的量、反应时间、固-液比等对钴浸取率的影响.经响应面分析实验结果表明,盐酸-30%过氧化氢最适宜做浸取液,最佳工艺条件为:盐酸浓度为4.0 mol/L,盐酸-30%过氧化氢体积比为5:1,反应时间61 min,反应温度73℃,固-液比(g/mL)为1:30.3,在此条件下,Co2+浸出率达到99.8%.

  3. 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

  4. 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.

  5. 从废钒催化剂酸浸液中萃取钒%Solvent Extraction of Vanadium From Acidic Leaching Solution of Waste Catalyst

    Institute of Scientific and Technical Information of China (English)

    郝喜才; 姬学亮

    2014-01-01

    Solvent extraction of vanadium from acidic leaching solution of waste catalyst containing vanadium using TOA as extractant was researched . The optimum process parameters were determined .The results show that using the 10% TOA + 4% decanol+ 86% sulfonated kerosene as extraction agent ,at the conditions of aqueous phase pH of 2 .5 ,the volume ratio between organic phase and aqueous phase of 1∶3 ,contact time of 2 .5 min ,holding time of 5 min ,single stage extraction of vanadium is up to 95 .2% .Using 0 .6 mol/L Na2 CO3 solution and be two stages back‐extraction ,the 99% of vanadium in organic phase was stripped .The stripping liquid can be directly precipitated vanadium .Calcining the precipitate can acquire V2 O5 product with GB3283 -1987 metallurgical grade 99 standard .The extraction raffinate is centralized processing .The process is simple and has remarkable comprehensive benefit .%研究了用TOA作萃取剂从废钒催化剂酸浸液中萃取钒,考察了各影响因素对钒萃取率的影响,确定了最佳萃取参数。试验结果表明:用10% TOA+4%癸醇+86%磺化煤油作萃取剂,在水相pH=2.5、有机相与水相体积比(V o ∶V a )=1∶3、萃取时间2.5 min、静置时间5 min条件下,钒的单级萃取率高达95.2%;用0.6 mol/L Na2 CO3溶液进行2级反萃取,钒的反萃取率在99%以上;反萃取液可直接沉淀钒,产品V2 O5质量达到GB3283—1987冶金99级标准。萃余液可集中处理。该工艺简单,综合效益显著。

  6. 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)

  7. Leaching of aluminum and iron from boiler slag generated from a typical Chinese Steel Plant.

    Science.gov (United States)

    Li, Jinping; Gan, Jinhua; Li, Xianwang

    2009-07-30

    This paper presents a new way of recycling aluminum and iron in boiler slag derived from coal combustion plants, which integrates efficient extraction and reuse of the leached pellets together. The boiler slag was pelletized together with washed coal and lime prior to sintering and then was sintered at 800-1200 degrees C for different periods to produce sintered pellets for the leaching test. An elemental analysis of aqueous solutions leached by sulfuric acid was determined by EDTA-Na(2)-ZnCl(2) titration method. The components and microstructures of the samples, sintered pellets and leached residue were examined by means of XRF, XRD and SEM. XRD analysis indicates that predominate minerals such as kaolinite, quartz, calcium silicide, hematate and metakoalin exist in the boiler slag. An aluminum extraction efficiency of 86.50% was achieved. The maximum extraction efficiency of Fe was 94.60% in the same conditions of that for the maximum extraction efficiency of Al. The extraction efficiencies of Al and Fe increased with an increase in temperature, leaching time and acidity. High Al extraction efficiency was obtained for pellets with high CaO content. The final product of alumina would be used directly for the production of metallic aluminum.

  8. 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.

  9. Leaching and recycling of zinc from liquid waste sediments

    Institute of Scientific and Technical Information of China (English)

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

    2008-01-01

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

  10. 用电容去离子技术去除含钒酸浸液中的磷%Phosphorus Removal from Vanadium-containing Acid Leaching Solution by Capacitive Deionization Technology

    Institute of Scientific and Technical Information of China (English)

    周嘉郁; 张一敏; 包申旭; 段继华

    2016-01-01

    石煤提钒酸浸液中含有的大量磷会直接影响后续钒的净化富集,从而影响五氧化二钒的产品纯度,甚至使产品质量不达标。采用环境友好型吸附技术———电容去离子技术( CDI)对石煤酸浸液中磷的去除条件进行了研究,并研究了电极材料对磷的吸附机理。结果表明,当施加电压为2.0 V,进料流量为25 mL/min,溶液初始pH=0.75,电极间距为9 mm时,对酸浸液中磷、钒的去除率分别为63.28%和1.30%,较好地去除了含钒酸浸液中的磷。 Medusa软件模拟和红外光谱分析表明,石煤酸浸液中的磷主要以H2 PO-4和PO3-4形式被电极吸附,吸附过程既有物理吸附又有化学吸附。%There are mass of phosphorus in stone coal acid leaching solution which will affect the subsequent vanadium extraction process and the purity of V2 O5 , which could make the product unqualified. Research on phosphorus removal from acid leaching solution by an environmentally friendly desalination technology-capacitive deionization ( CDI ) was uconduct-ed. The effect of operational parameters on the phosphorus removal and the adsorption mechanism of phosphorus were investiga-ted. The results show that 63. 28% phosphorus and only 1. 30% vanadium could be removed under the optimum conditions of 2. 0 V charging voltage,flow rate of 25 mL/min,pH of 0. 75 and the distance between polar plates of 9 mm. CDI has good sepa-ration performance of phosphorus from the stone coal acid leaching solution. The calculation by Medusa software and the FTIR analysis showed the phosphorus in stone coal acid leaching solution was adsorbed by electrode in forms of H2 PO-4 and PO3-4 . Meanwhile,the adsorption process included both physical adsorption and chemical adsorption.

  11. Acid Leaching of Calcined Vanadium Titanomagnetite with Calcium Compounds for Extraction of Vanadium%钒钛磁铁矿钙化焙烧及其酸浸提钒

    Institute of Scientific and Technical Information of China (English)

    李兰杰; 张力; 郑诗礼; 娄太平; 张懿; 陈东辉; 张燕

    2011-01-01

    对钒钛磁铁矿精矿钠化焙烧水浸提钒和钙化焙烧酸浸提钒的效果进行对比,确定钙化焙烧-硫酸浸出提钒方法,研究了焙烧添加剂Na2CO3,CaO,Ca(OH)2和CaCO3对浸出提钒效果的影响,其中CaCO3的作用最好,确定了CaCO3添加量为10%,1 200℃焙烧时间为1h的优化焙烧条件,得到主要的含钒物相为偏钒酸钙相;偏钒酸钙在pH<1.35和2.5~4的硫酸溶液及pH<1和4~6.7的盐酸中可溶解,但酸浸所得铁精矿熟料中偏钒酸钙在pH 0.5、液固质量比5:1的硫酸溶液中80℃浸出3h可更好溶出,钒浸出率可达72.1%.%After comparing the results of vanadium extraction by roasting the mixture of calcium-bearing regents with vanadium titanomagnetite concentrate and leaching by deionized water and roasting the mixture of sodium-bearing regents with iron concentrate and leaching by acid, the extraction method of vanadium by roasting the mixture of calcium-bearing reagents with iron concentrate and leaching by sulfuric acid is proposed. Among roasting additives of Na2CO3, CaO, Ca(OH)2 and CaCO3, CaCO3 has the best effect for vanadium extraction. The optimal roasting conditions obtained are the additive dosage 10%, roasting temperature 1200 V and roasting time 1 h with CaCO3, and the primary vanadium-bearing phase generated is calcium metavanadate. It can be dissolved in sulfuric acid solution at pHacid solution at pHacid leaching results show that calcium metavanadate in iron concentrate roasted can be leached when pH at 0.S, mass ratio of liquid to solid at 5:1, 80 ℃ and 3 h. The leaching rate of vanadium is 72.1 % from the roasted concentrate.

  12. 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

  13. Leaching of Fluoride from Biotite Mica in Soil: Implications for Fluoride in Shallow Groundwater

    OpenAIRE

    Kularatne, K. U. K. S.; Pitawala,H. M. T. G. A.

    2012-01-01

    Leaching of F − from biotite was investigated at room temperature by performing a series of short-term leach tests. The leaching of F − from biotite structure strongly depends on its weathering stage. Results of this study suggest that high concentration of F − is leached from highly weathered biotite, compared to fresh biotite. Results of dissolution experiments confirm that the organic acids in soil promote the leaching of F − from biotite compared to inorganic acids. Citric acid which is a...

  14. 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.

  15. 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.

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

    Energy Technology Data Exchange (ETDEWEB)

    Jha, Manis Kumar, E-mail: maniskrjha@gmail.com [Metal Extraction and Forming Division, National Metallurgical Laboratory (NML), Jamshedpur 831 007 (India); Choubey, Pankaj Kumar; Jha, Amrita Kumari; Kumari, Archana [Metal Extraction and Forming Division, National Metallurgical Laboratory (NML), Jamshedpur 831 007 (India); Lee, Jae-chun, E-mail: jclee@kigam.re.kr [Mineral Resources Research Division, Korea Institute of Geosciences and Mineral Resources, Daejeon 305-350 (Korea, Republic of); Kumar, Vinay [Metal Extraction and Forming Division, National Metallurgical Laboratory (NML), Jamshedpur 831 007 (India); Jeong, Jinki [Mineral Resources Research Division, Korea Institute of Geosciences and Mineral Resources, Daejeon 305-350 (Korea, Republic of)

    2012-10-15

    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 5.5 M HCl at fixed pulp density 50 g/L and temperature 90 Degree-Sign 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 4.5 M HCl at 90 Degree-Sign 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 0.1 M nitric acid at 90 Degree-Sign C in mixing time 45 min and pulp density 10 g/L. The metal free epoxy resin could be disposed-of safely/used as filling material without affecting the environment.

  17. ExperimentaL study on the gaLLium recovery by optimized acid Leaching of aLumina red mud%氧化铝赤泥回收镓的优化浸出试验研究

    Institute of Scientific and Technical Information of China (English)

    柯胜男; 刘锦卉; 郭晓娟; 赵婷婷; 王海芳

    2016-01-01

    Red mud is a type of solid waste from production of alumina.In order to reduce the consumption of acid and increase the leaching rate of gallium,the method of orthogonal test was used to compare the leaching rate of gallium between directly leac-hing gallium with sulfuric acid and curing the red mud with concentrated sulfuric acid for a period of time.The gallium in the red mud was converted into soluble compounds after the pretreatment and ready to leach in the subsequent leaching process.The op-timization experimental conditions are as follows:in the curing process,the ratio of the sulfuric to the red mud is 2 to 1,the red mud is cured for 2 h at 200 ℃ and the concentration of sulfuric acid is 4 mol/L.In the leaching process,5 g curing red mud is in water baths for 60 minutes at 70 ℃,water amount 20 mL and 5 % calcium fluoride.About 95 % of the gallium can be extracted from the red mud in this way.%以氧化铝生产过程中的固体废弃物赤泥为主要原料,通过酸浸回收镓时,为了降低酸的消耗量,提高镓的浸出率,采用正交试验法比较直接硫酸酸浸浸出镓和先用浓硫酸熟化赤泥,将其中的镓转化成水溶性化合物,再从预处理物料中浸出镓2种试验。研究结果表明提取、回收镓的最适宜条件是:在熟化过程中,熟化温度为200℃,熟化时间为2 h,硫酸浓度为4 mol/L,硫酸和水与赤泥的液固比为2∶1;进行水浸时,浸出温度为70℃,浸出时间为60 min,5 g 熟化赤泥中加水量为20 mL,含氟助浸剂5%(氟化钙占赤泥的质量分数)。在此条件下,最终浸出率可达95%左右。

  18. 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.

  19. 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.

  20. 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)

  1. 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.)

  2. Reseach on Acid Leaching Processes of A Nickel-copper Laterite Silicate Ore From Qinghai%用硫酸从青海含铜红土型硅酸镍矿石浸出镍、铜试验研究

    Institute of Scientific and Technical Information of China (English)

    陈晓鸣; 张昱; 王春梅; 严鹏; 陈力行

    2014-01-01

    研究了青海某含铜红土型硅酸镍矿石的常压和加压酸浸。试验结果表明:对于常压酸浸,在磨矿粒度-0.15 mm占95%、硫酸用量80%、浸出温度90℃、液固质量比2.3∶1、浸出时间3 h条件下,镍、铜浸出率分别为86.8%和92.6%;对于加压酸浸,在磨矿细度-0.15 mm占95%、硫酸用量60%、浸出温度120℃、液固体积质量比1.5∶1、浸出时间2h条件下,镍、铜浸出率分别为92.4%和94.0%。常压酸浸与加压酸浸均可得到较高的金属浸出率,但加压酸浸效率更高,且对杂质金属铁的浸出有一定抑制作用。%T he comparison tests for atmosphere leaching and pressure leaching of a nickel-copper laterite silicate ore from Qinghai were conducted .The results showed that both atmosphere leaching and pressure leaching can gain high leaching rate .At the conditions of atmosphere ,temperature of 90℃ ,ore granularity of -100 mesh accounting for 95% ,acid usage of 800 kg/t ores ,pulp density of 30% and agitation time of 3 h ,the leaching rate of Ni and Cu is 86 .8% and 92 .6% ,respectively .While at the conditions of pressure (202 kPa ) ,temperature of 120 ℃ ,ore granularity of - 100 mesh accounting for 95% ,acid usage of 600 kg/t ores ,pulp density of 40% ,and agitation leaching time of 2h ,the leaching rate of Ni and Cu is 92 .4% and 94 .0% ,respectively .However ,compared with the atmosphere leaching ,the pressure leaching can gain a higher leaching rate ,w hat is more important that it would have some inhibiting effect for Fe leaching .

  3. 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)

  4. 氧压浸出炼锌渣处理工艺研究%The Treatment Technology on Waste Residues from Zinc Smelting byOxygen Pressure Acid Leaching

    Institute of Scientific and Technical Information of China (English)

    陈锋

    2016-01-01

    According to the harmless treatment of waste residues and the comprehensive recovery of valuable metal which are produced by oxygen pressure acid leaching of zinc smelting, the analysis are carried out for waste residues from zinc smelting by oxygen pressure acid leaching technology, such as the rotary kiln volatilization, rotary kiln reducing roasting, oxygen-enriched bath smelting, oxygen-enriched stock column smelting. Thereby the treatment process and process flow, technology parameters, economic indicators for the different waste residues are proposed.%针对氧压浸出炼锌产出的废渣进行无害化处理和有价金属综合回收问题,对回转窑挥发、回转窑还原焙烧、富氧熔池熔炼、富氧料柱熔炼处理氧压浸出炼锌渣工艺技术进行分析研究,提出不同情况的废渣可以采用的处理工艺及其工艺流程、技术参数、经济指标等.

  5. 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 .

  6. Recovery of copper and cobalt from low-grade heterogenite with reductive acid leaching method%还原酸浸法从低品位水钴矿中提取铜和钴

    Institute of Scientific and Technical Information of China (English)

    刘俊; 李林艳; 徐盛明; 池汝安

    2012-01-01

    Copper and cobalt were leached from heterogenite in sulfuric acid using Na2SO3 as reducing agent, and the influences of the type and amount of reducing agent, leaching temperature, acid concentration, etc on leaching rates of copper and cobalt were investigated through single-factor experiments. The results show that the optimal conditions, at which the leaching efficiencies of copper and cobalt were 99.06% and 98.87%, were as follows: the dosage of Na2SO3 is 10% of the mass of heterogenite, and c(H2SO4)=3 mol/L, T=60 ℃, L/S ratio=2:l, t=60 min. The proposed flowsheet is Cu recovery by M5640→Fe removal by jarosite→A1 removal by Na2CO3→Ca, Mg removal by NaF→evaporative crystallization valuable. This process flow can be applied in the extraction of metals from heterogenite and similar materials effectively in industry.%以Na2SO3为还原剂从水钴矿还原酸浸液中提取铜和钴,研究了还原剂种类及用量、浸出温度、硫酸浓度等因素对水钴矿还原酸浸过程中有价金属铜和钴浸出率的影响.结果表明,Na2SO3是较适宜的还原剂;在还原剂用量为水钴矿原矿质量的10%、硫酸浓度为3 mol/L、浸出温度为60℃、液固比为2∶1、浸出时间为60 min的条件下,铜和钴的浸出率分别达99.06%和98.87%.并提出了“M5640萃铜→黄钠铁矾法除铁→碳酸钠除铝→氟化钠除钙、镁→蒸发结晶得钴产品”的后续分离净化流程,能有望应用于水钴矿及类似物料中有价金属的提取与分离的工业生产.

  7. 钒渣无焙烧浸出液中钒铁萃取分离%Separation Between Vanadium and Iron in Acid Leaching Solution of Converter Vanadium Slag Without Calcination

    Institute of Scientific and Technical Information of China (English)

    张莹; 张廷安; 吕国志; 刘卓林

    2015-01-01

    In view of a new process of leaching the converter vanadium slags with titanium dioxide waste acid under the pressure without calcination proposed by our research group,V extraction from the solution which using waste acid leaching vanadium slag was studied using P204 as the extraction agent.The results showed that the reduction of ferric iron into ferrous iron by Na2 SO3 as a pretreatment reducing agent prevented ferric irons co-extracted into the leaching liquid.Under the optimal technological condition:at room temperature,leaching solution original pH of 2.5,the volume ratio of the aqueous phase to oil phase of 1 ∶3 and the shaking time of 4 min,the extraction rate of V is more than 98.61 %,and the separation factor between V and Fe is up to 135.3 using the 20%P204 with 10%TBP synergistic extraction system.%利用本课题组提出的钛白废酸无焙烧加压浸出钒渣提钒的新技术,以 P204为萃取剂从废酸浸出钒渣的浸出液中进行了提钒研究.实验结果表明:采用亚硫酸钠为浸出液预处理还原剂,将浸出液中三价铁还原成二价铁,从而防止三价铁的共萃;常温条件下,当浸出液初始 pH =2.5、水相与有机相体积比为1∶3,震荡时间为4 min 时,采用有机相组成为20%P204及10%TBP 协同萃取体系,钒的萃取率可达98.61%以上,钒铁的分离系数可达135.3.

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

    Energy Technology Data Exchange (ETDEWEB)

    Mendel, J.E.; Harker, A.B.

    1985-01-01

    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. 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.

  10. Recovery of copper from galvanic sludge by reductive roasting combined with acid leaching%还原焙烧-酸浸回收电镀污泥中的铜

    Institute of Scientific and Technical Information of China (English)

    陈娴; 程洁红; 顾冬梅

    2011-01-01

    采用还原焙烧—酸浸工艺处理电镀污泥,可以实现对铜的选择性回收.研究了不同焙烧条件下,电镀污泥的失重率和金属含量,并探索了焙烧温度、焙烧时间、煤粉用量、CaCO3投加量对金属浸出率的影响.结果表明,还原焙烧有利于污泥减量和金属富集;并且经还原焙烧污泥中金属的浸出效果明显优于直接焙烧;在电镀污泥中添加10%(质量分数)的煤粉和0.5%(质量分数)的CaCO3,于700℃焙烧20 min后,在焙烧底渣投加量为20 g/L(每升10%(质量分数)的硫酸溶液投加20 g焙烧底渣)、振荡速度为112 r/min、浸出时间为60 min、室温条件下进行酸浸,Cu浸出率高达98.73%,而Ni、Zn、Cr的浸出率较低,从而使目标金属Cu和其他金属初步分离.%The experiments of reductive roasting and acid leaching the galvanic sludge were preformed to selective recovery the copper from sludge. The weight decreasing rate and metals concentration of galvanic sludge under various roasting conditions were detected and the effect of roasting temperature, roasting time, dosage of fine coal and CaCO3 on leaching rate of metals was investigated. The results showed that reductive roasting was more excellent than direct roasting in both sludge quantity reduction and heavy metal enrichment, and metal leaching efficiency of reductive roasting treated sludge was better than that of direct roasted sludge. The leaching rate of Cu reached 98. 73% after the galvanic sludge treated by the following conditions: reductive roast at 700 ℃ for 20 min with the presence of 10% (mass ratio) fine coal and 0. 5% (mass ratio) CaCO3, and then acid leaching by 10% of H2SO4 for 60 min at room temperature with liquid-to-solid ratio of 20 g/L and stirring speed of 112 r/min. Simultaneously, leaching quantity of Ni, Zn, Cr were much less, so the target metal Cu was finally separated from other metals.

  11. 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.

  12. Impact of wheat straw biochar addition to soil on the sorption, leaching, dissipation of the herbicide (4-chloro-2-methylphenoxy)acetic acid and the growth of sunflower (Helianthus annuus L.).

    Science.gov (United States)

    Tatarková, Veronika; Hiller, Edgar; Vaculík, Marek

    2013-06-01

    Biochar addition to agricultural soils might increase the sorption of herbicides, and therefore, affect other sorption-related processes such as leaching, dissipation and toxicity for plants. In this study, the impact of wheat straw biochar on the sorption, leaching and dissipation in a soil, and toxicity for sunflower of (4-chloro-2-methylphenoxy)acetic acid (MCPA), a commonly used ionizable herbicide, was investigated. The results showed that MCPA sorption by biochar and biochar-amended soil (1.0wt% biochar) was 82 and 2.53 times higher than that by the non-amended soil, respectively. However, desorption of MCPA from biochar-amended soil was only 1.17 times lower than its desorption in non-amended soil. Biochar addition to soil reduced both MCPA leaching and dissipation. About 35% of the applied MCPA was transported through biochar-amended soil, while up to 56% was recovered in the leachates transported through non-amended soil. The half-life value of MCPA increased from 5.2d in non-amended soil to 21.5 d in biochar-amended soil. Pot experiments with sunflower (Helianthus annuus L.) grown in MCPA-free, but biochar-amended soil showed no positive effect of biochar on the growth of sunflower in comparison to the non-amended soil. However, biochar itself significantly reduced the content of photosynthetic pigments (chlorophyll a, b) in sunflower. There was no significant difference in the phytotoxic effects of MCPA on sunflowers between the biochar-amended soil and the non-amended soil. Furthermore, MCPA had no effect on the photosynthetic pigment contents in sunflower.

  13. New technology of iron extraction and gold recovery from cyanide tailings by cyanide process after reduction roasting and acid leaching%氰化尾渣还原焙烧酸浸提铁及氰化浸金新工艺

    Institute of Scientific and Technical Information of China (English)

    郑雅杰; 龚昶; 孙召明

    2014-01-01

    The cyanide tailings were treated by reduction roasting and acid leaching. The cyanide tailings were reduced under conditions of reduction temperature 850℃, the mass ratio of pulverized coal to cyanide tailings 13%and reduction time 100 min. Fe2O3 in the cyanide tailings is turned into Fe3O4 or FeO. The reduced cyanide tailings were leached by sulfuric acid under conditions of a concentration of sulfuric acid 50%, the sulfuric acid dosage coefficient 1.2, leaching temperature 105℃and leaching time 3 h. The leaching rate of Fe is 93.66%. The leaching rate of Au is 92.4%under conditions of sodium cyanide dosage 4 kg/t, leaching time 28 h, the ratio of liquid to solid 2:1 after acidic residue is roasted at 600 ℃for 2 h to remove carbon. The mass of cyanide tailings decreases by 38.8%after reduction roasting, sulfuric acid leaching, oxidizing roasting and cyanide leaching.%以氰化尾渣为原料,采用还原焙烧酸浸工艺对其进行处理。当还原温度为850℃、加入煤粉质量为氰化尾渣质量的13%、还原时间为100 min时,对氰化尾渣进行还原,氰化尾渣中Fe2O3转化为Fe3O4或FeO。还原后采用硫酸浸出,当硫酸浓度为50%、硫酸用量系数为1.2、反应温度为105℃、反应时间为3 h时,铁的浸出率达到93.66%。还原焙烧渣在600℃氧化焙烧2 h经过脱碳后氰化浸金,当氰化钠用量为4 kg/t、反应时间为28 h、液固比为2:1时,金的浸出率达到92.4%。经过还原焙烧、硫酸浸出、氧化焙烧及氰化浸金,氰化尾渣渣量减少了38.8%。

  14. Facilitated Leaching of Additive-Derived PBDEs from Plastic by Seabirds' Stomach Oil and Accumulation in Tissues.

    Science.gov (United States)

    Tanaka, Kosuke; Takada, Hideshige; Yamashita, Rei; Mizukawa, Kaoruko; Fukuwaka, Masa-Aki; Watanuki, Yutaka

    2015-10-06

    Our previous study suggested the transfer of polybrominated diphenyl ether (PBDE) flame retardants from ingested plastics to seabirds' tissues. To understand how the PBDEs are transferred, we studied leaching from plastics into digestive fluids. We hypothesized that stomach oil, which is present in the digestive tract of birds in the order Procellariiformes, acts as an organic solvent, facilitating the leaching of hydrophobic chemicals. Pieces of plastic compounded with deca-BDE were soaked in several leaching solutions. Trace amounts were leached into distilled water, seawater, and acidic pepsin solution. In contrast, over 20 times as much material was leached into stomach oil, and over 50 times as much into fish oil (a major component of stomach oil). Analysis of abdominal adipose, liver tissue, and ingested plastics from 18 wild seabirds collected from the North Pacific Ocean showed the occurrence of deca-BDE or hexa-BDEs in both the tissues and the ingested plastics in three of the birds, suggesting transfer from the plastic to the tissues. In birds with BDE209 in their tissues, the dominance of BDE207 over other nona-BDE isomers suggested biological debromination at the meta position. Model calculation of PBDE exposure to birds based on the results of the leaching experiments combined with field observations suggested the dominance of plastic-mediated internal exposure to BDE209 over exposure via prey.

  15. 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

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

    Science.gov (United States)

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

    2016-09-01

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

  17. 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.

  18. 加压酸浸法回收红土矿中的镍、钴%Recovery of Nickel and Cobalt from Laterite with High Pressure Acid Leaching Technology

    Institute of Scientific and Technical Information of China (English)

    陈彩霞; 席海龙; 贺来荣; 杨粉娟; 马晶

    2014-01-01

    研究了某褐铁矿层红土矿加压酸浸处理工艺,通过小试确定了各工艺过程的最佳条件.加压酸浸:温度为255℃,加酸量为250 kg/t,时间为60 min,矿浆体积分数为30%,镍、钴浸出率分别为98.23%和98.77%;矿浆中和:终点pH为1.5~2.0,时间为60 min,温度为90℃;溶液处理采用两段除杂法:用氢氧化钠进行镍、钴沉淀,终点pH为7.6,得到了氢氧化镍钴中间产品;用氧化钙沉淀废水中的金属离子,使废水达到排放要求.%This paper mainly studied the technology of recovery of nickel and cobalt from laterite with high pressure acid leaching.The optimum conditions were determined.In the processing of pressure acid leaching,the nickel and cobalt leaching rate reached 98.23% , 98. 77% ,respectively,in the condition of temperature 255 ℃ ,the acid consumption 250 kg/t ore,the reaction time 60 min and pulp density 30% .The best conditions for pulp neutralization are:the end point pH 1.5-2.0,the reaction time 60 min,the temperature 90 ℃ .The solution was treated by two-stage process and end pH is 7. 6. Intermediate products of nickel and cobalt hydroxide were produced.After treating with calcium oxide, the wastewater could be discharged eligibly.

  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. Presentation

    Directory of Open Access Journals (Sweden)

    Helmut Renders

    2008-10-01

    Full Text Available We present to our esteemed readers the second edition of our journal for 2008. We have chosen the theme “The life and work of Prof. Dr. Jürgen Moltmann” as its special emphasis. It is our way to pay homage to J. Moltmann in the year the Universidade Metodista de São Paulo awards him an honorary Doctor Honoris Causa degree. Sincethe seventies, Moltmann and Latin America have been in dialog. In his emblematic work “A Theology of Liberation”, Gustavo Gutiérrez, the Catholic, discussed with Moltmann, the Reformed, the relationship between eschatology and history (GUTIÉRREZ, Gustavo.Teologia da Libertação. 5ª edição. Petrópolis, RJ: Vozes, 1985, p. 27, 137-139. A dialog held in the premises of IMS, which nowadays is called UMESP, has produced the little book “Passion for life” (MOLTMANN, Jürgen. Paixão pela vida. São Paulo, SP: ASTE - Associaçãode Seminários Teológicos Evangélicos, 1978.In the following years, the wide theological work of J. Moltmann went all the way from debates to congresses and has conquered the classrooms. Most probably, J. Moltmann is nowadays the most widely read European author in Brazilian theological seminaries. Thisrecognition can only be held in unison and the wide response to our request for articles confirms the huge repercussion that Moltmann’s work has been having up to today in Brazil. The ecumenical theologian J. Moltmann is ecumenically read. We believe that thisway we may be better equipped to answer to anyone who asks us for the reason there is hope in us. We have organized the articles on J. Moltmann’s theology according to the original publication date of the books dealt with in each essay. We also communicate that some articles which were originally requested for this edition of the journal will be published in the journal Estudos de Regilião in May 2009.As it is usual with the journal Caminhando, we have, besides this thematic emphasis, yet other contributions in the areas of

  1. Chalcopyrite leaching: The rate controlling factors

    Science.gov (United States)

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

    2010-05-01

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

  2. Folic acid use in pregnant patients presenting to the emergency department

    OpenAIRE

    Steenblik, Jacob; Schroeder, Erika; Hatch, Burke; Groke, Steven; Broadwater-Hollifield, Camille; Mallin, Michael; Ahern, Matthew; Madsen, Troy

    2011-01-01

    Background The US Preventive Services Task Force has recommended daily folic acid supplementation for women planning on becoming pregnant in an effort to prevent fetal neural tube defects. We evaluated pregnant patients presenting to the emergency department to determine rates of folic acid supplementation. Methods We surveyed a convenience sample of pregnant patients who presented to the University of Utah Emergency Department (ED) between 1 January 2008, and 30 April 2009, regarding pregnan...

  3. 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

  4. 硫化氢脱除镍钴溶液中锌杂质研究%Research on Removing Zinc from Nickel and Cobalt Acid Pressure Leaching Solution by H2S

    Institute of Scientific and Technical Information of China (English)

    张磊; 黄振华; 何德利

    2016-01-01

    According to the diffidence of the solubility product , the zinc and copper should be precipitated by H2S in the nickel and cobalt acid pressure leaching solution. The precipitation rates of zinc and copper are beyond 80% with the loss rate of nickel is below 1%.%针对镍钴加压浸出液,通过硫化物沉淀溶度积的不同,采用硫化氢对镍钴溶液中的锌、铜进行沉淀,除锌铜率≥80%,镍损失率≤1%,达到选择性除锌的效果。

  5. 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.

  6. Purification of vein quartz by mixed acid thermal pressure leaching and it 's mechanism%混合酸热压浸出纯化脉石英及机理

    Institute of Scientific and Technical Information of China (English)

    臧芳芳; 雷绍民; 钟乐乐; 裴振宇; 杨亚运; 熊康

    2016-01-01

    The high purity quartz was prepared using mixed acid at thermal pressure leaching .The influential factors such as concentration of HF ,HCl and HNO3 , liquid-solid ratio ,reaction time and temperature on purification of vein quartz as thermal pressure leaching were investigated .The results showed that the rate of removal of impurity metal elements Fe ,Al ,Ca ,Mg ,K ,Na were respectively 67.04% ,96 .96% ,84 .97% ,73 .18% ,76 .25% ,and 58 .97% at the optimizational process parameters . During this thermal pressure leaching ,the mixed acid could not only be reacted with impurity mineral on the surface of quartz particles ,but also be diffused into the interface or inside along the crack of quartz crystal particles .It will be lattice distorted owing to the part of interstitial atoms dissolved out and resulting that the silicon oxygen tetrahedral arrangement the transition from the rule to the irregular in the crystals of quartz which increasing the probability of the dissolution of the metal atom and in favor of quartz purification .%采用混合酸热压浸出方法制备高纯石英.研究了HF、HCl、HNO3浓度、液固比、反应时间、反应温度对热压浸出纯化脉石英的影响.结果表明:在优化的技术条件下,脉石英中杂质金属元素Fe、Al、Ca、M g、K、Na去除率分别可达67.04%、96.96%、84.97%、73.18%、76.25%及58.97%.热压浸出过程中,混合酸溶液不仅能与石英晶体表面杂质矿物反应,还能沿缝隙扩散进入石英晶体界面或晶体内部,部分填隙式金属原子溶出导致石英晶体中硅氧四面体排列由规则向不规则过渡,即晶格发生畸变,增加了石英晶格中金属原子溶出的几率,有利于石英纯化.

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. Experimental research on recovering silver from high acid zinc leaching residue with flotation%从高酸锌浸出渣中浮选回收银的试验研究

    Institute of Scientific and Technical Information of China (English)

    查辉; 葛英勇; 罗衡; 黄龙

    2013-01-01

      针对甘肃某湿法炼锌厂锌浸出渣组成复杂、粒度细、酸性强的特点,对该锌浸出渣进行了载体浮选回收银试验。试验结果表明,载体浮选可有效回收该锌浸出渣中银。试验确定以 AC-0为载体、石灰为 pH 调整剂、丁铵黑药和 GC 为捕收剂,通过一粗一精一扫和中矿集中返回粗选的浮选流程,在自然pH(2)和 pH =4条件下,分别可获得银品位为3363g/t 、回收率为71.01%和银品位为3760g/t 、回收率为69.47%的银精矿,实现了锌浸出渣中银的回收利用。%Aiming at the characteristics of complicated compositions ,fine size and high acidity of the zinc leaching residues produced from a zinc hydrometallurgy factory in Gansu ,the paper describes some experiments on recovering silver from them with carrier flotation .The results of the tests show that the silver can be recovered effectively from the zinc leaching residues by carrier flotation .With AC-0 as carrier , lime as pH adjustment agent ,ammonium dibutyl dithio phosphate and GC as collectors ,through the flotation flow sheet of one roughing ,one cleaning and one scavenging ,with the middlings returning to the roughing ,at natural pH(2) and pH = 4 ,the silver concentrates with the grade of 3363g/t silver ,recovery of 71 .01% and the grade of 3760g/t silver ,recovery of 69 .47% can be obtained respectively .The recovery of silver from zinc leaching residue is realized .

  12. 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.

  13. 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.

  14. 由混合电镀污泥硫酸浸出液选择性沉淀分离铬的研究%Recovery of chromium from sulphuric acid leaching solutions of mixed electroplating sludge by selective precipitation

    Institute of Scientific and Technical Information of China (English)

    徐志峰; 赵洪兴; 王成彦; 袁文辉; 杨卜

    2015-01-01

    The recovery of Cr from the sulphuric acid leaching solutions of mixed electroplating sludge (MES) is studied. After the removal of Cu by solvent extraction, the selective phosphate precipitation is applied for the separation of Cr from Fe, Ni and Zn in the MES leaching solutions. The experimental results show that the precipitation of Cr can be carried out stably and effectively and the concentration of Cr in the solutions can be lowered down to about 0.04 g/L. Cr is efficiently enriched in the precipitates which contain 13% of Cr, 0.4 %of Ni, 0.1%of Fe and 0.2%of Zn,respectively,and could be further recovered as economic products.%研究由混合电镀污泥硫酸浸出液选择性分离回收铬的方法.浸出液经萃取提铜后,应用磷酸沉淀方法实现铬与铁、镍、锌的选择性分离.实验证明,该方法稳定有效,能够达到选择性沉淀铬的目的,沉淀后液中铬的浓度可降至0.04 g/L左右.沉铬渣含铬约13%,镍、铁、锌等杂质含量可分别降至0.4%、0.1%和0.2%左右.由磷酸铬渣可进一步综合回收铬并制取铬的经济产品.

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

    Science.gov (United States)

    Brandt, H C; de Groot, P C

    2001-12-01

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

  17. 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

  18. 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.

  19. 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/...

  20. Neurologic presentations of acid-base imbalance, electrolyte abnormalities, and endocrine emergencies.

    Science.gov (United States)

    Yee, Alan H; Rabinstein, Alejandro A

    2010-02-01

    Accurate identification of nervous system dysfunction is vital in the assessment of any multisystem disorder. The neurologic manifestations of acid-base disturbances, abnormal electrolyte concentrations, and acute endocrinopathies are protean and typically determined by the acuity of the underlying derangement. Detailed history and physical examination may guide appropriate laboratory testing and lead to prompt and accurate diagnosis. Neurologic manifestations of primary and secondary systemic disorders are frequently encountered in all subspecialties of medicine. This article focuses on key neurologic presentations of respiratory and metabolic acid-base derangements and potentially life-threatening endocrinopathies.

  1. 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.

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

    OpenAIRE

    Caroline Michael; R.Wilfred Sugumar

    2013-01-01

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

  3. 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.

  4. Study on removal of silicon and preparation of high purity ferric oxide red from acid leaching filtrate of tailings%尾矿酸浸液除硅以及制备高纯铁红的研究

    Institute of Scientific and Technical Information of China (English)

    廖攀; 陈学安; 常新安; 肖卫强; 王少华

    2012-01-01

    Acid leaching filtrate of tailings from Jinchuan Company contains not only large amount of Fe2+ but also small amount of Si4*.Using CaO as neutralizer and polyacrylamide as flocculation reagent,the optimum technological conditions of removal of silicon from the acid leaching filtrate were obtained by orthogonal experiments.After silicon was removed,goethite was prepared under the conditions of 85 t and stirring by using MgO as neutralizer and air together with H2O2 as nxirlant.Finally the high purity ferric oxide red (a-Fe2O3) was prepared by calcining goethite at calcining temperature of 800℃ for 2 h followed by washing with 5% dilute HNO3. The mass fraction of main content of the as-prepared iron red was 99.2% .which could be classified as the qualified product according to the national standard of HG/T 2574?009.%金川公司尾矿酸浸液中除含有较高含量的铁之外,还含有一定量的杂质硅.以氧化钙为中和剂,聚丙烯酰胺为絮凝剂,通过正交设计与实验,得出了从该酸浸液中除硅的较佳工艺条件;随后,以氧化镁为中和剂,空气和双氧水为氧化剂,将除硅后滤液在85℃搅拌加热,制得针铁矿沉淀;最后将沉淀在800℃煅烧2h并经过5%稀硝酸洗涤得到了高纯铁红,其主成分质量分数为99.2%,符合HG/T 2574-2009工业氧化铁国家标准.

  5. Use of dolomite phosphate rock (DPR) fertilizers to reduce phosphorus leaching from sandy soil.

    Science.gov (United States)

    Chen, G C; He, Z L; Stoffella, P J; Yang, X E; Yu, S; Calvert, D

    2006-01-01

    There is increasing concern over P leaching from sandy soils applied with water-soluble P fertilizers. Laboratory column leaching experiments were conducted to evaluate P leaching from a typical acidic sandy soil in Florida amended with DPR fertilizers developed from dolomite phosphate rock (DPR) and N-Viro soil. Ten leaching events were carried out at an interval of 7 days, with a total leaching volume of 1,183 mm equivalent to the mean annual rainfall of this region during the period of 2001-2003. Leachates were collected and analyzed for total P and inorganic P. Phosphorus in the leachate was dominantly reactive, accounting for 67.7-99.9% of total P leached. Phosphorus leaching loss mainly occurred in the first three leaching events, accounting for 62.0-98.8% of the total P leached over the whole period. The percentage of P leached (in the total P added) from the soil amended with water-soluble P fertilizer was higher than those receiving the DPR fertilizers. The former was up to 96.6%, whereas the latter ranged from 0.3% to 3.8%. These results indicate that the use of N-Viro-based DPR fertilizers can reduce P leaching from sandy soils.

  6. How are the Concepts and Theories of Acid-Base Reactions Presented? Chemistry in Textbooks and as Presented by Teachers

    Science.gov (United States)

    Furio-Mas, Carlos; Calatayud, Maria Luisa; Guisasola, Jenaro; Furio-Gomez, Cristina

    2005-01-01

    This paper investigates the views of science and scientific activity that can be found in chemistry textbooks and heard from teachers when acid-base reactions are introduced to grade 12 and university chemistry students. First, the main macroscopic and microscopic conceptual models are developed. Second, we attempt to show how the existence of…

  7. 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

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

    Science.gov (United States)

    Xu, Ying; Chen, Yu

    2015-07-01

    The chelator [S,S]-ethylene diamine disuccinic acid, citric acid, and biosurfactant saponin are selected as leaching agents. In this study, the leaching effect of saponin mixed with either ethylene diamine disuccinic acid or citric acid on the levels of copper, zinc, lead, and cadmium in municipal solid waste incinerator fly ash is investigated. Results indicate that saponin separately mixed with ethylene diamine disuccinic acid and citric acid exhibits a synergistic solubilisation effect on copper, zinc, lead, and cadmium leaching from fly ash. However, saponin and ethylene diamine disuccinic acid mixed solution exhibits a synergistic solubilisation effect that is superior to that of a saponin and citric acid mixed solution. The extraction rate of heavy metal in fly ash leached with a saponin and chelator mixed solution is related to the pH of the leaching solution, and the optimal range of the pH is suggested to be approximately neutral. After leaching with a saponin and chelator mixed solution, copper, zinc, lead, and cadmium contents significantly decreased (p < 0.05) in the extractable or acid-soluble and reducible fractions. By adopting the proposed approach, the leaching concentrations of copper, zinc, lead, and cadmium in treated fly ash are in accordance with Standard for Pollution Control on the Security Landfill Site for Hazardous Wastes GB18598-2001.

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

    OpenAIRE

    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...

  10. PHYTOCHEMICAL EVALUATION OF HYDROXY CITRIC ACID, CATECHINS AND CALCIUM PANTOTHENATE PRESENT IN HERBAL FORMULATION

    Directory of Open Access Journals (Sweden)

    S. P. Karuppiah

    2012-01-01

    Full Text Available The analytical method for the estimation of phytochemical active ingredients present in Garginia combogia extract, Green tea extract with calcium pantothenate for herbal formulations are evaluated for it’s Assay content and dissolution release. This herbal formulation with slim formula consists of several active ingredients such as Hydroxy Citric acid, catechins and calcium pantothenate. The HPLC method for the estimation of active content and the in-vitro dissolution release is developed for the study.

  11. 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.

  12. 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.

    Science.gov (United States)

    Larner, Bronwyn L; Palmer, Anne S; Seen, Andrew J; Townsend, Ashley T

    2008-02-11

    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 (4h, 1 molL(-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 micromolg(-1)) showed no significant difference in element partitioning following oxidation, whilst sediments containing high AVS levels (>100 micromolg(-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 (SigmaSteps 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.

  13. 低冰镍转炉渣中钴的氧压酸浸行为及其动力学%Kinetics and behavior of cobalt extraction from low nickel matte converter slag by pressure oxidative leaching with sulfuric acid

    Institute of Scientific and Technical Information of China (English)

    廖亚龙; 黄斐荣; 周娟; 李冰洁

    2015-01-01

    The dissolution kinetics and behavior of cobalt extraction from low nickel matte converter slag by pressure oxidative leaching with sulfuric acid were investigated. The effects of stirring speed, temperature, sulfuric acid concentration, oxygen partial pressure and particle size on extraction rate of cobalt were studied for exploring the kinetics law of cobalt dissolution from the slag. The experimental results showed that the extraction efficiency of cobalt increased with the increases of temperature, sulfuric acid concentration and oxygen partial pressure, but the sulfuric acid concentration above 40 g·L–1 can cause an increase of iron extensive dissolving in the solution. The stirring speeding above 700 r·min–1, oxygen partial pressure beyond 650 kPa and particle size of less than 74μm were found to have no effect on the extraction of cobalt. The dissolution kinetics analysis of the experimental data based on the shrinking core model for various conditions indicated that the reaction rate of leaching was mainly controlled by the chemical reaction during its early stages, then switched to be controlled by mixed chemical-reaction and product-layer diffusion, and finally was controlled solely by diffusion through a surface product layer in the later stage. The activation energy was calculated to be 43.19 kJ·mol–1 in the early surface chemical reaction controlled stage and 10.49kJ·mol–1 in the later diffusion controlled stage, respectively. In the chemical reaction controlled stage, the reaction orders with respect to sulfuric acid concentration, oxygen partial pressure and particle size are 0.79, 0.85and –0.95,respectively.%研究了转炉渣中钴氧压硫酸体系选择性浸出过程的行为及其动力学。通过改变搅拌速度、反应温度、硫酸浓度、氧分压、物料粒度以及反应时间等浸出条件,考察钴浸出率的变化及影响,获得转炉渣中钴的浸出动力学规律。结果表明,钴的浸出率随着

  14. 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.

  15. 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。

  16. Silver Recovery from Acid Leaching Slag of Zinc Smelting with Hydrometallurgical Process%全湿法工艺回收锌冶炼酸浸渣中的银

    Institute of Scientific and Technical Information of China (English)

    王康柱; 王正民; 周熙; 周玺

    2013-01-01

    锌冶炼酸浸渣先浮选再用硫脲富集获得粗银绵,粗银绵经化学法提纯后经过电解产出纯度达99.95%以上的成品银,全流程银回收率达到70%以上.还可同时回收金和铜,含锌液返回锌冶炼系统,且无三废产生.%Crude silver powder was obtained by flotation and thiourea enrichment from acid leaching slag of zinc smelting.Crude silver powder was purified by chemical method and electrolyzed to produce silver product with purity of 99.95% plus.The silver recovery rate is more than 70%.Gold and copper are recovered simultaneously and zinc is returned to zinc smelting system.There are no three wastes in the whole process.

  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. 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)

  19. Thiosulfate leaching of gold from waste mobile phones.

    Science.gov (United States)

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

    2010-06-15

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

  20. Extended Leach Testing of Simulated LAW Cast Stone Monoliths

    Energy Technology Data Exchange (ETDEWEB)

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

    2015-07-09

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

  1. 硝酸浸取磷矿制轻质碳酸钙工艺研究%Preparation of light calcium carbonate by nitric acid leaching phosphate ore

    Institute of Scientific and Technical Information of China (English)

    胡兆平; 贾洪秀; 庞世花; 刘阳; 贾亮

    2013-01-01

    Calcium nitrate crystal can be obtained by freezing crystallization method from acid solution acquired from nitric acid extracting phosphate rock.After that,light calcium carbonate was prepared by carbonization reaction between ammonium hydrogen carbonate and calcium nitrate crystal.Results show that,the initial carbonization reaction temperature was the normal temperature,mass fraction of calcium nitrate solution was about 23%,ammonium hydrogen carbonate and ammonia dosages were both 110% of theoretical addition amounts,and products were washed by four times of product weight washing water.All quality indexes of the product can meet the standard of Industrial Precipitated Calcium Carbonate,HG/T 2226-2000.%硝酸萃取磷矿后的酸解液,通过冷冻结晶法得到硝酸钙晶体,然后以硝酸钙为原料,通过加入碳酸氢铵进行碳化制取轻质碳酸钙.结果表明,碳化反应的初始反应温度为常温,硝酸钙溶液的质量分数为23%左右,碳酸氢铵和氨水按理论加入量的110%进行反应,用产品质量的4倍洗水量洗涤产品,制备的轻质碳酸钙产品各项指标均达到HG/T 2226-2000《工业沉淀碳酸钙》标准的要求.

  2. Spatial distribution and leaching behavior of pollutants from phosphogypsum stocked in a gypstack: Geochemical characterization and modeling.

    Science.gov (United States)

    Bisone, Sara; Gautier, Mathieu; Chatain, Vincent; Blanc, Denise

    2017-05-15

    Phosphogypsum (PPG) is the byproduct of the production of phosphoric acid and phosphate fertilizers from phosphate rocks (PR) by acid digestion. Despite the technical feasibility, the impurities present in this waste make its reuse critical and large amounts of PPG are stockpiled, resulting in the production of polluted acid leachates. The aim of the present study was to characterize the spatial variability and evolution in time of a 20-year-old gypstack and to study the geochemical behavior of the waste in order to assess the best management options. Chemical and mineralogical analyses were performed on core samples taken from 4 different depths of the stack down to 13.5 m. Despite the high homogeneity shown by chemical and mineral characterization, leaching tests revealed a different chemical behavior with depth. pH-dependent leaching tests were also performed to measure the acid neutralization capacity of the studied matrices and to determine the leachability of the elements or pollutants of concern as a function of pH. The study was focused on Ca, Fe Na, Si, Cd and Sr and on F(-), PO4(3-) and SO4(2-) anions. The geochemical modeling of these tests with PHREEQC enabled the identification of the minor phases controlling the solubilization of the elements analyzed. Validation of the model by the simulation of a column leaching test suggested that the model could be used as a predictive tool to assess different management scenarios.

  3. Leaching properties of Mn-slag from the pyrometallurgical recycling of alkaline batteries: standardized leaching tests and influence of operational parameters.

    Science.gov (United States)

    Pareuil, Priscilla; Bordas, François; Joussein, Emmanuel; Bollinger, Jean-Claude

    2010-12-14

    In the present study, different complementary leaching tests were applied to a Mn-rich slag sample that was not thoroughly studied until now, in order to understand the potential mobility of the elements (Mn, Si, Fe, Ca, K, Mg, Al) within it. Several standard leaching tests (EN 12457-1 and -2, and TCLP) were carried out in order to compare results to regulatory values: the Mn-rich slag studied could be considered as 'inert' waste with respect to the release of the main trace metallic elements (Cu, Ni and Zn). In order to have a better understanding of the environmental behaviour of the Mn-rich slag constituents, other tests were performed. These experiments revealed that the dissolution of the Mn-rich slag was favoured for pH MINTEQ modelling allowed the leaching results to be completed. From an environmental point of view, the reuse of this slag in acidic conditions has to be rejected due to the dissolution of the main solid phase.

  4. 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.

  5. 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%.

  6. 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 .

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

    Science.gov (United States)

    1991-01-01

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

  8. A case of mania presenting with hypersexual behavior and gender dysphoria that resolved with valproic acid

    Directory of Open Access Journals (Sweden)

    Michelle R. Heare

    2016-11-01

    Full Text Available Hypersexuality and gender dysphoria have both been described in the literature as symptoms of mania. Hypersexuality is listed in the Diagnostic and Statistical Manual of Mental Disorders 5 as part of the diagnostic criteria for bipolar disorder. Gender dysphoria is less often described and its relation to mania remains unclear. This case report describes a young homosexual man presenting in a manic episode with co-morbid amphetamine abuse whose mania was marked by hypersexuality and the new onset desire to be a woman. Both of these symptoms resolved with the addition of valproic acid to antipsychotics. This case report presents the existing literature on hypersexuality and gender dysphoria in mania and describes a treatment option that has not been previously reported.

  9. A Case of Mania Presenting with Hypersexual Behavior and Gender Dysphoria that Resolved with Valproic Acid

    Science.gov (United States)

    Heare, Michelle R.; Barsky, Maria; Faziola, Lawrence R.

    2016-01-01

    Hypersexuality and gender dysphoria have both been described in the literature as symptoms of mania. Hypersexuality is listed in the Diagnostic and Statistical Manual of Mental Disorders 5 as part of the diagnostic criteria for bipolar disorder. Gender dysphoria is less often described and its relation to mania remains unclear. This case report describes a young homosexual man presenting in a manic episode with co-morbid amphetamine abuse whose mania was marked by hypersexuality and the new onset desire to be a woman. Both of these symptoms resolved with the addition of valproic acid to antipsychotics. This case report presents the existing literature on hypersexuality and gender dysphoria in mania and describes a treatment option that has not been previously reported. PMID:27994833

  10. Hyaluronic acid-coated chitosan nanoparticles: molecular weight-dependent effects on morphology and hyaluronic acid presentation.

    Science.gov (United States)

    Almalik, Abdulaziz; Donno, Roberto; Cadman, Christopher J; Cellesi, Francesco; Day, Philip J; Tirelli, Nicola

    2013-12-28

    Chitosan nanoparticles are popular carriers for the delivery of macromolecular payloads, e.g. nucleic acids. In this study, nanoparticles were prepared via complexation with triphosphate (TPP) anions and were successively coated with hyaluronic acid (HA). Key variables of the preparative process (e.g. chitosan and HA molecular weight) were optimised in view of the maximisation of loading with DNA, of the Zeta potential and of the dimensional stability, and the resulting particles showed excellent storage stability. We have focused on the influence of chitosan molecular weight on nanoparticle properties. Larger molecular weight increased their porosity (=decreased cross-link density), and this caused also larger dimensional changes in response to variations in osmotic pressure or upon drying. The dependency of nanoparticle porosity on chitosan molecular weight had a profound effect on the adsorption of HA on the nanoparticles; HA was apparently able to penetrate deeply into the more porous high molecular weight (684 kDa) chitosan nanoparticles, while it formed a corona around those composed of more densely cross-linked low molecular weight (25 kDa) chitosan. Atomic Force Microscopy (AFM) allowed not only to highlight the presence of this corona, but also to estimate its apparent thickness to about 20-30 nm (in a dry state). The different morphology has a significant effect on the way HA is presented to biomolecules, and this has specific relevance in relation to interactions with HA receptors (e.g. CD44) that influence kinetics and mechanism of nanoparticle uptake. Finally, it is worth to mention that chitosan molecular weight did not appear to greatly affect the efficiency of nanoparticle loading with DNA, but significantly influenced its chitosanase-triggered release, with high molecular chitosan nanoparticles seemingly more prone to degradation by this enzyme.

  11. 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.

  12. 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)

  13. 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

  14. 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 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.

  15. 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.

  16. 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.

  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. 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.

  19. [Remediation of Cu-Pb-contaminated loess soil by leaching with chelating agent and biosurfactant].

    Science.gov (United States)

    Liu, Xia; Wang, Jian-Tao; Zhang, Meng; Wang, Li; Yang, Ya-Ti

    2013-04-01

    Because of its strong chelation, solubilization characteristics, the chelating agents and biosurfactant are widely used in remediation of heavy metals and organic contaminated soils. Ethylenediamine tetraacetic acid (EDTA), citric acid (CIT) and dirhamnolipid (RL2) were selected as the eluent. Batch experiments and column experiments were conducted to investigate the leaching effect of the three kinds of eluent, as well as the mixture of biosurfactant and chelating agent for Cu, Pb contaminated loess soil. The results showed that the leaching efficiencies of different eluent on Cu, Pb contaminated loess soil followed the sequence of EDTA > CIT > RL2. At an eluent concentration of 0.02 mol x L(-1), the Cu leaching efficiency was 62.74% (EDTA), 52.28% (CIT) and 15.35% (RL2), respectively; the Pb leaching efficiency was 96.10% (EDTA), 23.08% (CIT) and 14.42% (RL2), respectively. When the concentration of RL2 was 100 CMC, it had synergistic effects on the other two kinds of chelating agent in Cu leaching, and when the concentration of RL2 was 200 CMC, it had antagonism effects. The effect of RL2 on EDTA in Pb leaching was similar to that in Cu leaching. Pb leaching by CIT was inhibited in the presence of RL2. EDTA and CIT could effectively remove Cu and Pb in exchangeable states, adsorption states, carbonate salts and organic bound forms; RL2 could effectively remove Cu and Pb in exchangeable and adsorbed states.

  20. 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.

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

    OpenAIRE

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

    2011-01-01

    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...

  2. 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.

  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. Polymer structure modifications for immersion leaching and watermark control

    Science.gov (United States)

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

    2006-03-01

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

  5. Assessment of Pb, Cd, Cr and Ag leaching from electronics waste using four extraction methods.

    Science.gov (United States)

    Keith, Ashley; Keesling, Kara; Fitzwater, Kendra K; Pichtel, John; Houy, Denise

    2008-12-01

    Heavy metals present in electronic components may leach upon disposal and therefore pose significant environmental hazards. The potential leaching of Pb, Cd, Cr and Ag from PC cathode ray tubes, printed circuit boards (PCBs), PC mice, TV remote controls, and mobile phones was assessed. After controlled crushing, each component was extracted using the Toxicity Characteristic Leaching Procedure (TCLP), EPA Method 1312 (SPLP), NEN 7371 (Dutch Environmental Agency), and DIN S4 (Germany). The TCLP consistently leached the greatest amounts of Pb from all components. The SPLP, NEN 7371 and DIN S4 extracted relatively small amounts of metals compared with the TCLP and were not considered effective as leaching tests for e-waste. The smallest size fraction (< 2 mm) of CRT glass and PCBs leached significantly (p < 0.05) highest Pb via the TCLP. A modified TCLP removed 50.9% more extractable Pb compared with the conventional procedure.

  6. 粉煤灰硫酸浸出液中钛和铁的萃取分离%Extraction and Separation of Titanium and Iron with Sulfuric Acid Leaching of Fly Ash

    Institute of Scientific and Technical Information of China (English)

    薛茹君

    2011-01-01

    By adjusting the pH of the H2SO4 leaching liquor of fly ash, Ti4 + and Fe + were extract-separated with trioctylphosphineoxide (TOPO)-kerosene and di ( 2-ethylhexyl) phosphoric acid (P204)-kerosene, respectively. Effects of the extractants, the concentration of the cations, pH of the aqueous solution, extracting temperature, and extracting time on the extracting efficiency were investigated. Effect of the recycle conditions of the loaded extractants on the recovery yield and the purity of recovered products were discussed as well. The phase of the precursor and its calcined products were characterized by X-ray diffraction(XRD). The purity of the TiO2 and Fe2O3 were determined by X-ray fluorescence (XRF). The analysis results show that the extracting-titanium efficiency and the extracting-iron efficiency were as high as 97%. The extraction yields of ferric oxide and titanium dioxide are 96% and greater than 92% , respectively. The purities of TiO2 and Fe2O3 are 98% and 97% , respectively, which can be used as a white pigment or iron oxide red pigment in the production of paints, respectively.%将粉煤灰的硫酸浸出液,用氨水调节pH值后,用三正辛基氧膦-煤油、磷酸二异辛酯-煤油萃取分离溶液中的Ti和Fe.考察了萃取剂、水相阳离子浓度、pH值及萃取温度和时间等实验条件对萃取率的影响;讨论了萃取剂再生条件对提取率及分离产物纯度的影响.用XRD表征了反萃取煅烧产物的物相组成,用X射线荧光分析测定了煅烧产物TiO和FeO的纯度.分析结果表明,钛的萃取率达到97%,提取率>92%;铁的萃取率达到97%,提取率达到96%;TiO和FeO的纯度分别为98%和97%,均可以用作涂料的颜料.

  7. 酒石酸淋洗过程中土壤重金属解吸动力学特征%Kinetics Characteristics of Heavy Metals Desorption from Contaminated Soil during Tartaric Acid Leaching

    Institute of Scientific and Technical Information of China (English)

    刘岚昕

    2012-01-01

    采用批处理淋洗的方法,研究了酒石酸淋洗修复张士污灌区土壤过程中镉、铅、铜、锌4种重金属离子解吸动力学特征.结果表明,酒石酸在12h条件下,达到对污染土壤中镉离子的最大去除率,铅、铜、锌3种重金属离子达到最大去除率则需要24 h.4种重金属离子的解吸动力学过程可以用Elovich方程很好的描述,说明酒石酸去除重金属离子的过程是一种非均相扩散过程.此外,解吸速率曲线显示,反应初期相同时刻上酒石酸对铅离子的解吸速率最快,其次是铜和锌,最后是镉离子;反应后期同一时刻上铜和锌的解吸速率大于铅和镉.%The kinetics characteristics of four heavy metals, namely Cd, Pb, Cu, Zn, desorption from contaminated soil during tartaric acid leaching to restore Zhangshi sewage irrigation area were studied by batch experiments. The results showed that the maximum removal of Cd was within 12h, while the maximum removal of Cu, Pb and Zn were within 24h. Desorption behaviors of four heavy metals were described by Elovich model well. This meant desorption process belonged to heterogeneous diffusion. In addition, desorption rate curve indicated that the order of desorption rate was Pb > Cu=Zn > Cd in the beginning of reaction, while the rates of Cu and Zn were faster than that of Pb and Cd at the end of reaction.

  8. 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.

  9. Dietary trans fatty acids and cardiovascular disease risk: past and present.

    Science.gov (United States)

    Lichtenstein, Alice H

    2014-08-01

    Dietary trans double bond containing fatty acids have been associated with increased risk of cardiovascular disease. There are two main sources of dietary trans fatty acids: meat and dairy fats, and partially hydrogenated fats. Because of a number of factors, including changes in federal labeling requirements for packaged foods, and local bans and grassroots pressure on the use of partially hydrogenated fat, trans fat intake has declined in recent years. Similar to saturated fatty acids, trans fatty acids increase plasma low density lipoprotein (LDL)-cholesterol concentrations. In contrast to saturated fatty acids, trans fatty acids do not increase high density lipoprotein (HDL)-cholesterol concentrations. These differences have been attributed to lipoprotein catabolic rate rather than production rate. When reported, effects of partially hydrogenated fat on glucose homeostasis, C-reactive protein, blood pressure, and LDL oxidation are modest. Although at this time some issues remain unresolved regarding trans fatty acids and CVD risk factors other than plasma lipoprotein concentrations, they should not affect the final dietary recommendation to limit intake.

  10. 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.

  11. Bioleaching of spent hydrotreating catalyst by acidophilic thermophile Acidianus brierleyi: Leaching mechanism and effect of decoking.

    Science.gov (United States)

    Bharadwaj, Abhilasha; Ting, Yen-Peng

    2013-02-01

    Bioleaching of spent hydrotreating catalyst by thermophillic archae Acidianus brierleyi was investigated. The spent catalyst (containing Al, Fe, Ni and Mo as major elements) was characterized, and the effect of pretreatment (decoking) on two-step and spent medium leaching was examined at 1% w/v pulp density. Decoking resulted in removal of carbonaceous deposits and volatile impurities, and affected the solubility of metal compounds through oxidization of the metal sulfides. Nearly 100% extraction was achieved using spent medium leaching for Fe, Ni and Mo, and 67% for Al. Bioleaching reduced nickel concentration in the leachate below the regulated levels for safe waste disposal. Chemical (i.e. abiotic) leaching using equimolar concentration of sulfuric acid produced by the bacteria during two-step process achieved a lower leaching efficiency (by up to 30%). Results indicated that A. brierleyi successfully leached heavy metals from spent catalyst.

  12. Kinetics of the Carbonate Leaching for Calcium Metavanadate

    Directory of Open Access Journals (Sweden)

    Peiyang Shi

    2016-10-01

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

  13. 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.

  14. 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.

  15. Spectrophotometric Determination of Scandium in Hydrochloric Acid Leaching Solution of Red Mud%赤泥盐酸浸出液中钪的分光光度测定

    Institute of Scientific and Technical Information of China (English)

    邓海霞; 王克勤; 王皓; 李爱秀; 张风林; 陈津

    2011-01-01

    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:温度对吸光度值不产生大的影响,在室温下测试即可;溶液显色在前8min内不稳定,其显色时间一定要达到10 min,溶液颜色保持16h不发生太大的变化;显色剂氯代磺酚C和Sc(Ⅲ)1∶1络合稳定,其溶液加入量确定为3ml;酸度对吸光度有较大的影响,待测溶液的pH值为2.0时吸光度值最大,且稳定.溶液最大吸光度波长为649 nm,工作曲线回归方程为y=0.03839x -0.0002,相关系数的平方为0.9993,Sc(Ⅲ)的质量浓度在0~1.2 mg·L-1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.本法测定赤泥盐酸浸出液中的钪,结果比较稳定,RSD(n =6)为1.45%~4.16%,加标回收率为98%~ 102%,灵敏度高、结果较满意.%The effects of temperature, time, reagent dosage, solution pH on absorbance showed that: the temperature had little effect on the absorbance, the solution could be tested at room temperature; the determination result was not stable within the first 8 min, the solution should achieve a coloration time for 10 mins, the solution color maintained 16 h did not change much; reagent chlorosulpho-phenol C and Sc( IB) 1:1 complex stability, the solution was added 3 ml; acidity had great influence on the absorbance with pH value of 2.0, the maximum absorbance, and stability. Hie maximum absorbance of solution was at 649 nm, and the standard curve regression equation: y = 0.03839* - 0.0002, the square of correlation coefficient was 0.9993, Lambert-Beer law was obeyed for Sc (JE ) in the range of 0 -1.2 rag-L"' and the apparent molar absorptivity was 7.78 xlO3 L-mol~1>cm~l. The method was applied to the determination of Sc( HI) in hydrochloric acid leaching solution of red mud, the result was stable with high sensitivity and satisfactory, RSD ( n = 6) was 1.45%-4.16% and the recovery of Sc( I) was 98% to 102%.

  16. 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.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2013-08-01

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

  18. 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.

  19. Enhanced sensing of dopamine in the present of ascorbic acid based on graphene/poly(p-aminobenzoic acid) composite film.

    Science.gov (United States)

    Huang, Ke-Jing; Jing, Qiang-Shan; Wu, Zhi-Wei; Wang, Lan; Wei, Cai-Yun

    2011-11-01

    Graphene/p-aminobenzoic acid composite film modified glassy carbon electrode (Gr/p-ABA/GCE) was first employed for the sensitive determination of dopamine (DA). The electrochemical behavior of DA at the modified electrode was investigated by cyclic voltametry (CV), differential pulse voltametry (DPV) and amperometric curve. The oxidation peak currents of DA increased dramatically at Gr/p-ABA/GCE. The modified electrode was used to electrochemically detect dopamine (DA) in the presence of ascorbic acid (AA). The Gr/p-ABA composite film showed excellent electrocatalytic activity for the oxidation of DA in phosphate buffer solution (pH 6.5). The peak separation between DA and AA was large up to 220 mV. Using DPV technique, the calibration curve for DA determination was obtained in the range of 0.05-10 μM. The detection limit for DA was 20 nM. AA did not interfere with the determination of DA because of the very distinct attractive interaction between DA cations and the negatively Gr/p-ABA composite film. The proposed method exhibited good stability and reproducibility.

  20. 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...

  1. A European test of pesticide-leaching models: methodology and major recommendations

    NARCIS (Netherlands)

    Vanclooster, M.; Boesten, J.J.T.I.; Trevisan, M.; Brown, C.D.; Capri, E.; Eklo, O.M.; Gottesbüren, B.; Gouy, V.; Linden, van der A.M.A.

    2000-01-01

    Testing of pesticide-leaching models is important in view of their increasing use in pesticide registration procedures in the European Union. This paper presents the methodology and major conclusions of a test of pesticide-leaching models. Twelve models simulating the vertical one-dimensional moveme

  2. 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

  3. 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.

  4. Leaching kinetics of gibbsitic bauxite with sodium hydroxide

    Directory of Open Access Journals (Sweden)

    Abdel-Aal El-Sayed A.

    2016-01-01

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

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

    Science.gov (United States)

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

    2016-09-01

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

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. Radiocesium leaching from contaminated litter in forest streams.

    Science.gov (United States)

    Sakai, Masaru; Gomi, Takashi; Naito, Risa S; Negishi, Junjiro N; Sasaki, Michiko; Toda, Hiroto; Nunokawa, Masanori; Murase, Kaori

    2015-06-01

    In Japanese forests suffering from the Fukushima Daiichi Nuclear Power Plant accident, litter fall provides a large amount of radiocesium from forests to streams. Submerged litter is processed to become a vital food resource for various stream organisms through initial leaching and subsequent decomposition. Although leaching from litter can detach radiocesium similarly to potassium, radiocesium leaching and its migration are poorly understood. We examined both radiocesium and potassium leaching to the water column and radiocesium allocation to minerals (glass beads, silica sand, and vermiculite) in the laboratory using soaked litter with and without minerals on a water column. The mineral types did not affect radiocesium leaching from litter, but soaking in water for 1, 7, and 30 days decreased the radiocesium concentration in litter by ×0.71, ×0.66, and ×0.56, respectively. Meanwhile, the 1-, 7-, and 30-day experiments decreased potassium concentration in litter by ×0.17, ×0.11, and ×0.09, respectively. Leached radiocesium remained in a dissolved form when there was no mineral phases present in the water, whereas there was sorption onto the minerals when they were present. In particular, vermiculite adsorbed radiocesium by two to three orders of magnitude more effectively than the other minerals. Because radiocesium forms (such as that dissolved or adsorbed to organic matter or minerals) can further mobilize to ecosystems, our findings will increase our understanding regarding the dynamics of radiocesium in stream ecosystems.

  11. [Modeling research on impact of pH on metals leaching behavior of air pollution control residues from MSW incinerator].

    Science.gov (United States)

    Zhang, Hua; He, Pin-Jing; Li, Xin-Jie; Shao, Li-Ming

    2008-01-01

    Metals leaching behavior of air pollution control residues (APC residues) from municipal solid waste incinerator (MSWI) is greatly dependent on the leachate pH. pH-varying leaching tests and Visual MINTEQ modeling were conducted to investigate the mechanism of pH effect on the metals leaching characteristics from MSWI APC residues. Results show that, under acidic environment (for Cd, Zn, and Ni, pH < 8; for Pb, Cu, and Cr, pH < 6; for Al, pH < 4), leaching concentrations of metals increase greatly with the decrease of pH. Release of amphoteric metals, Pb and Zn, can be induced in strong alkaline leachate, reaching to 42 and 2.4 mg x L(-1) at pH 12.5 respectively. The equilibrium modeling results are well in agreement with the analyzed leaching concentrations. Variation of leachate pH changes the metals speciation in the leaching system, thus influencing their leaching concentrations. Speciation and leaching behavior of Pb, Zn, Cu, Ca, and Al mainly depend on their dissolution/precipitation reactions under different leachate pH. Leachability of Cd, Cr, and Ni can be lowered under acidic and neutral leachate pH due to HFO adsorption, while under alkaline conditions, the effect of adsorption is not significant and dissolution/precipitation becomes the major reactions controlling the leaching toxicity of these heavy metals.

  12. 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.

  13. 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.

  14. 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.

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

    Energy Technology Data Exchange (ETDEWEB)

    Gates, D.D.; Chao, K.K.; Cameron, P.A.

    1995-07-01

    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/I{sub 2} 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/I{sub 2} 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/I{sub 2}, 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.

  16. Leaching behaviour of rock materials and a comparison with slag used in road construction

    OpenAIRE

    Tossavainen, Mia

    2000-01-01

    Leaching characteristics are used for the evaluation of secondary materials used in road construction. In order to form a basis for comparison of the leachability, Swedish rock material have been investigated using the availability test NT ENVIR 003. Microscopic studies of the mineral composition, Acid-Base-Accounting and pH-measurements have been used to explain the leaching results. Overall, the content of identified opaque minerals is low and the leachable amounts of the heavy metal elemen...

  17. Nitrate leaching from Silage Maize

    OpenAIRE

    Hansen, Elly Møller; Eriksen, Jørgen

    2009-01-01

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

  18. 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.

  19. 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.

  20. 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

  1. 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.

  2. 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.

  3. 泥质氧化矿搅拌酸浸综合节能技术%Comprehensive Energy-Saving Technology of Agitation Acid Leaching on Argillaceous Oxidized Ore

    Institute of Scientific and Technical Information of China (English)

    王洪江; 吴爱祥; 张仪; 金正聪; 顾晓春

    2012-01-01

    常规搅拌浸出工艺投资大、能耗高、成本高.为此,采用矿石分级处理、工业余热利用、高效浓密进行澄清与洗涤,分别取代了矿石细磨、矿浆加热以及浸渣压滤工艺.试验结果表明,分级处理技术使得泥质矿浆-0.074 mm达到81.33%,工业余热利用使得矿浆在50 min内反应温度提高到60℃,高效浓密技术实现了矿浆的浓缩、澄清、洗涤三大功能.三项综合节能技术的应用,使浸出系统的总装机容量下降了33%,投资额下降了68.5%,成本下降了35.3%.通过对搅拌工艺的优化研究,拓展了搅拌浸出的应用范围.%High investment, high energy consumption and high cost are features of normal agitation leaching. Therefore, the technology of fine grinding on ore, slurry heating, and pressure filtration of leaching residue were substituted by the technology of classification treatment on ore, utilization of waste heat and clarification and washing with high-efficient thickening, respectively. The results show that the slurry a-chieves 81. 33% -0. 074 mm treated by classification, the temperature of slurry increased to 60 ℃ in 50 minutes using industrial waste heat, and the function of concentration, clarification and washing are a-chieved with the technique of high-efficient thickening. Under these comprehensive energy-saving techniques, the total installed capacity of leaching system was decreased by 33 %, investment by 68. 5 %, and the cost by 35. 3 %. With the optimization of agitation technique, application range in agitation leaching could be enlarged.

  4. 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).

  5. 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 ash and its 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.

  6. Thiourea leaching gold and silver from the printed circuit boards of waste mobile phones.

    Science.gov (United States)

    Jing-ying, Li; Xiu-li, Xu; Wen-quan, Liu

    2012-06-01

    The present communication deals with the leaching of gold and silver from the printed circuit boards (PCBs) of waste mobile phones using an effective and less hazardous system, i.e., a thiourea leaching process as an alternative to the conventional and toxic cyanide leaching of gold. The influence of particle size, thiourea and Fe(3+) concentrations and temperature on the leaching of gold and silver from waste mobile phones was investigated. Gold extraction was found to be enhanced in a PCBs particle size of 100 mesh with the solutions containing 24 g/L thiourea and Fe(3+) concentration of 0.6% under the room temperature. In this case, about 90% of gold and 50% of silver were leached by the reaction of 2h. The obtained data will be useful for the development of processes for the recycling of gold and silver from the PCBs of waste mobile phones.

  7. 采用HBL101从锌置换渣高酸浸出液中萃取锗%Germanium extraction from a high acid leaching solution of zinc replacing slag by HBL101

    Institute of Scientific and Technical Information of China (English)

    张魁芳; 曹佐英; 肖连生; 曾理; 张贵清; 李青刚

    2015-01-01

    针对现行的湿法炼锌渣中提取锗的研究现状,采用新型萃取剂HBL101从锌置换渣的高酸浸出液中直接萃取锗,考察了料液酸度、萃取剂体积分数、萃取温度、萃取时间和相比对萃取的影响以及氢氧化钠质量浓度、反萃温度、反萃时间和反萃相比对反萃的影响,并对萃取剂转型条件进行了研究.实验表明:有机相组成为30% HBL101+70%磺化煤油(体积分数)作为萃取剂,料液酸度为113.2 g·L-1 H2 SO4,其最佳萃取条件为萃取温度25℃,萃取时间20 min,相比O/A=1:4.经过五级逆流萃取,锗萃取率达到98.57%.负载有机相用150 g·L-1 NaOH溶液可选择性反萃锗得到高纯度锗酸钠溶液,其最佳反萃条件为反萃温度25℃,反萃时间25 min,相比O/A=4:1.经过五级逆流反萃,反萃率可达到98.1%.反萃锗后负载有机相再用200 g·L-1硫酸溶液反萃共萃的铜并转型,控制反萃温度25℃,反萃时间20 min,O/A=2:1.经过五级逆流反萃,铜反萃率可达到99.5%并完成转型,萃取剂返回使用.%Germanium extraction from a high acid leach solution of zinc replacing slag by a new extractant, HBL101, was tested based on the current research status on extracting germanium from zinc smelting slag in hydrometallurgy. Investigations were performed on the effects of feed acidity, extractant concentration, extraction time, extraction phase ratio and temperature on the extraction, the effects of NaOH concentration, stripping time, stripping phase ratio and temperature on the stripping of germanium, and the conditions of extractant transformation. The results show that with 30% HBL101 in 70% sulphonated kerosene ( volume fraction) as an extract-ant, the extraction rate of germanium from the solution with 113. 2 g·L-1 H2 SO4 reaches 98. 57% in five-stage counter current extrac-tion with a volume ratio of oil phase to aqueous phase, O/A ratio, of 1:4 at 25℃ for 20 min. Germanium in the loaded organic can be

  8. Leaching of 226Ra from components of uranium mill tailings

    Science.gov (United States)

    Landa, E.R.

    1991-01-01

    A sequential extraction procedure was used to characterize the geochemical forms of 226Ra retained by mixtures of quartz sand and a variety of fine-grained rock and mineral species. These mixtures had previously been exposed to the sulfuric acid milling liquor of a simulated acid-leach uranium milling circuit. For most test cases, the major fraction of the 226Ra was extracted with 1 mol/1 NH4Cl and was deemed to be exchangeable. However, 226Ra retained by the barite-containing mixture was resistant to both 1 mol/1 NH4Cl and 1 mol/HCHCl extraction. ?? 1991.

  9. 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.

  10. LEACHING OF METALS FROM MINERAL PROCESSING WASTE

    Science.gov (United States)

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

  11. Properties of Leach-Flessas-Gorringe polynomials

    Science.gov (United States)

    Pursey, D. L.

    1990-09-01

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

  12. 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.)

  13. 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

  14. 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...

  15. Phosphorus leaching in a soil textural gradient

    DEFF Research Database (Denmark)

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

    2009-01-01

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

  16. 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.  

  17. 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.

  18. 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

  19. Study on the Process of Extracting Vanadium from Stone Coal Vanadium Ore by No Pollution Oxidizer-Oxidizing-Acid Leaching%硅质石煤钒矿无污染氧化剂氧化—酸浸法提钒工艺研究

    Institute of Scientific and Technical Information of China (English)

    孙德四; 孙剑奇; 张贤珍

    2011-01-01

    The optimal technological parameters of the process of no pollution oxidizer-oxidizing were experimented by the test of single factor conditions. The results showed that the leaching rate of vanadium pentoxide is up to 72. 4% at the temperature 90℃ , manganese dioxide dosage 5% , concentration of sulfuric acid of 40% , particle size - 74 μm, leaching time 9 h, the mass ratio of liquid and solid 2. 5: 1. It is about 10% higher than the process of oxidization roasting with sodium salt%通过单因素条件试验确定了“氧化剂氧化—硫酸浸出提钒工艺”的最优工艺参数.试验结果表明,在氧化剂二氧化锰用量为5%、硫酸浓度为40%、浸出温度为90℃、矿物粒度- 74μm、浸出时间为9h、液固比为2.5:1的条件下,钒的浸出率可达72.4%.比起传统的钠化焙烧工艺高出10%以上.

  20. 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.

  1. 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.

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

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

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

  3. The ultrasonically assisted metals recovery treatment of printed circuit board waste sludge by leaching separation.

    Science.gov (United States)

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

    2009-10-15

    This paper provides a practical technique that realized industrial scale copper and iron separation from printed circuit board (PCB) waste sludge by ultrasonically assisted acid leaching in a low cost, low energy consumption and zero discharge of wastes manner. The separation efficiencies of copper and iron from acid leaching with assistance of ultrasound were compared with the one without assistance of ultrasound and the effects of the leaching procedure, pH value, and ultrasonic strength have been investigated in the paper. With the appropriate leaching procedure, a final pH of 3.0, an ultrasonic generator power of 160 W (in 1l tank), leaching time of 60 min, leaching efficiencies of copper and iron had reached 97.83% and 1.23%, respectively. Therefore the separation of copper and iron in PCB waste sludge was virtually achieved. The lab results had been successfully applied to the industrial scaled applications in a heavy metal recovery plant in city of Huizhou, China for more than two years. It has great potentials to be used in even the broad metal recovery practices.

  4. 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.

  5. Comparing soil chemistries of leached and nonleached copper-amended soils.

    Science.gov (United States)

    Schwertfeger, D M; Hendershot, W H

    2012-10-01

    Leaching metal-spiked samples has been proposed as a means to reduce the artifacts of the spiking procedure (e.g., salt effect, increased metal solubility) that can artificially increase metal bioaccessibility and toxicity in laboratory ecotoxicity tests. The effects on soil chemistry from leaching Cu-spiked samples were investigated by comparing chemistries of freshly spiked samples to samples that underwent the spike/leach procedure. Chemical parameters investigated included electrical conductivity (EC), pH, ethylenediaminetetraacetic acid- and CaCl(2) -extractable Cu, soil-solution Cu, Cu(2+) activity (estimated using Visual MINTEQ), and other solution parameters (dissolved organic carbon [DOC], Ca, Mg, Al). In leached samples, the electrical conductivity values of the spiked samples did not vary significantly from those of the control samples (p > 0.05), confirming that the leaching procedure had sufficiently minimized the salt effect. In the range of soil Cu concentrations where Cu ecotoxicity is expected, the pH in freshly spiked samples was as much as 0.52 units lower than the pH from leached samples at the same total-soil Cu concentration. The CaCl(2) -extractable fraction was up to 2.3-fold smaller in leached samples and inversely related to the pH of the spiked soil. Despite little to no difference in soil-solution Cu, up to 100-fold less Cu(2+) activity was observed in leached samples. Reduced Cu(2+) activity was related to less Al(3+) competition for DOC. Leaching resulted in solution chemistries that were more consistent with those of the control samples and reduced the artifacts of traditional soil-spiking procedures.

  6. 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.

  7. 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.

  8. 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.

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

    Institute of Scientific and Technical Information of China (English)

    邓锦勋; 李建华; 程威; 周磊

    2012-01-01

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

  10. A case of mania presenting with hypersexual behavior and gender dysphoria that resolved with valproic acid

    OpenAIRE

    Michelle R. Heare; Maria Barsky; Faziola, Lawrence R.

    2016-01-01

    Hypersexuality and gender dysphoria have both been described in the literature as symptoms of mania. Hypersexuality is listed in the Diagnostic and Statistical Manual of Mental Disorders 5 as part of the diagnostic criteria for bipolar disorder. Gender dysphoria is less often described and its relation to mania remains unclear. This case report describes a young homosexual man presenting in a manic episode with co-morbid amphetamine abuse whose mania was marked by hypersexuality and the new o...

  11. Experimental investigation of coating degradation during simultaneous acid and erosive particle exposure

    DEFF Research Database (Denmark)

    Møller, Victor Buhl; Dam-Johansen, Kim; Frankær, Sarah Maria

    When used in industrial processes, such as stirred acid leaching in the mineral industry, thermoset coatings are exposed to a combination of aggressive chemicals and erosive particlewear. While each exposure condition has been studied separately, no research has been presented on the effects...... of a simultaneous exposure. To investigate this, a pilot-scale stirred acid leaching tank, containing erosive particles and acidic solutions, has been designed and constructed. Resin types considered are amine-cured novolac epoxy and vinyl ester. Transient coating degradation is mapped through visual inspection...

  12. 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.

  13. Evaluation of leached metals in recovered aluminum coagulants from water treatment slurry.

    Science.gov (United States)

    Fouad, Mahmoud M; El-Gendy, Ahmed S; Razek, Taha M A

    2017-02-01

    The water treatment industry consumes large quantities of coagulant and produces huge amounts of slurry. The cost of alum used in water treatment, stringent regulations and negative impacts of sludge disposal are the motive to do integrated research studies on the technical feasibility of aluminum coagulant recovery from sludge using acidification. This work studied the leaching of iron, manganese, and chromium as the most extracted metals with aluminum during sludge acidification; furthermore, these metals have a great impact on the recovered coagulants' efficiency and treated water quality. The sludge used was collected from El-Sheikh Zayd water treatment plant in Egypt, then dried and ground; afterward, the effect of acid concentration, sludge mass, temperature, mixing speed and mixing time was studied. In addition, it was noticeable that the efficiency of sulfuric acid in leaching iron, manganese and chromium is higher than that of hydrochloric acid. Also, higher leaching for the three metals was obtained in all the experiments using higher acid concentration, elevated temperature, and rotational speed. Finally, the leached metals in recovered aluminum coagulants will not limit its application to water and wastewater treatment, as their concentrations are still very low if compared with aluminum, even with the highest leaching efficiency.

  14. 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.

  15. 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.

  16. 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.

  17. 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.

  18. Multivariate analysis for the evaluation of fiber, sugars, and organic acids in commercial presentations of table olives.

    Science.gov (United States)

    López-López, Antonio; Jiménez-Araujo, Ana; García-García, Pedro; Garrido-Fernández, Antonio

    2007-12-26

    Table olives constitute an important part of the Mediterranean diet and the diet of many non-olive-producing countries. The aim of this work was to determine the fiber, sugar, and organic acid contents in Spanish commercial presentations of table olives and characterize them by means of a multivariate analysis. The selection of variables was carried out on the basis of a canonical analysis and their classification, according to processing styles and cultivars, through a linear discriminant analysis. Values of dietary fiber in table olives ranged from 2 to 5 g/100 g edible portion (e.p.). Some stuffing materials (almond, hot red pepper, and hazelnut) or the addition of capers produced a significant increase in the total dietary fiber in green olives. Glucose, fructose, and mannitol were usually found in the ranges of 0-55, 0-70, and 0-107 mg/100 g e.p., respectively. Succinic acid was detected only in green and directly brined olives (0-40 mg/100 g e.p.), while lactic and acetic acids were used within the ranges of 0-681 and 5-492.8 mg/100 g e.p., respectively. A multivariate analysis showed that fiber, mannitol, and succinic, lactic, and acetic acids can be used to discriminate between processing styles (95.5% correct assignations) and cultivars (61.20%). Current data can also be used in the evaluation of the dietary value of table olives.

  19. 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

  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

    2016-11-05

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

  1. 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.

  2. Separation and Concentration of Indium from Leaching Solution Containing Indium, Antimony and Iron Ions

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Processing conditions of effectively separating indium from the leaching solution of a smelting antimony slag were studied. For the leaching solution containing indium and antimony and iron ions, indium was separated by extracting with HDEHP-kerosine solution, washing antimony and iron ions with oxalic acid solution and stripping indium with a dilute solution of hydrochloric acid. InCl3 solution with purity above 90% is obtained. Indium can be enriched through a circulation of stripping with a dilute HCl solution. The concentration of InCl3 solution is about 25~30 g/L.

  3. 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

  4. Leaching of Terbutryn and Its Photodegradation Products from Artificial Walls under Natural Weather Conditions

    DEFF Research Database (Denmark)

    Bollmann, Ulla E.; Minelgaite, Greta; Schluesener, Michael

    2016-01-01

    contacted with rainwater; thus, they reach surface waters where they might have adverse effects on aquatic organisms. The knowledge on the long-term leaching performance and especially the formation and fate of degradation products is rare. In the present study, the leaching of terbutryn from artificial...... walls equipped with two types of render was observed for 19 months. In addition to concentration and mass load determinations for terbutryn, photodegradation products were identified and studied in the leachate and render. The results show that terbutryn leached mainly within the first 6 -12 months...

  5. The pH-dependent leaching behavior of slags from various stages of a copper smelting process: Environmental implications.

    Science.gov (United States)

    Jarošíková, Alice; Ettler, Vojtěch; Mihaljevič, Martin; Kříbek, Bohdan; Mapani, Ben

    2017-02-01

    The leaching behaviors of primary copper (Cu) slags originating from Ausmelt, reverbatory, and converter furnaces operating under a single technological process were compared to a residual slag tailing obtained by slag re-processing via flotation and metal recovery. The EN 12457-2 leaching test, used for assessment of the hazardous properties, was followed by the CEN/TS 14997 pH-static leaching test (pH range 3-12). Both leaching experiments were coupled with a mineralogical investigation of the primary and secondary phases as well as geochemical modeling. Metals (Cd, Cu, Pb, Zn) exhibit the highest leaching at low pH. Under acidic conditions (pH 3-6), Ausmelt slag and slag tailing exhibited higher metal leaching compared to other slag types. Very low leaching of metals (far below EU limits for non-hazardous waste) was observed at natural pH (7.9-9.0) for all the studied slag samples. In contrast, relatively high leaching of As was observed over the entire pH range, especially for Ausmelt slag (exceeding the EU limit for hazardous waste by 1.7×). However, geochemical modeling and scanning electron microscopy indicated that formation of stable Ca-Cu-Pb arsenates and the binding of As to newly formed Fe (oxyhydr)oxides play an important role in efficient As immobilization at the slag-water interface. In contrast, no controls were predicted for Sb, whose leaching was almost pH-independent. Nevertheless Sb leached concentrations at natural pH were below EU limit for hazardous waste. Re-processing of primary Cu slags for metal recovery, and subsequent co-disposal of the resulting slag tailing with dolomite-rich mine tailing and local laterite is suitable for stabilizing the remaining contaminants (except Sb) and limiting their leaching into the environment.

  6. 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.

  7. 机械活化浸出废荧光粉中稀土氧化物实验研究%Research on the Mechanical Activation Leaching of REOs from Waste Fluorescent Powder

    Institute of Scientific and Technical Information of China (English)

    李雨; 徐欣欣; 雷鹰; 高志芳

    2016-01-01

    The mechanical activation leaching of REOs from waste fluorescent powder was conducted in this work.The effects of influent factors such as liquid-solid ratio,sulphuric acid concentration and leaching time were investigated.The alkali roasting followed by secondary leaching of residue was studied.The phase and elemental composition,and the microstructure of final leach residue were characterized by using X-ray diffraction (XRD),scanning electron microscope (SEM) and electron probe microanalysis (EMPA).The experimental results show that the leaching rate of Y2O3 and Eu2O3 are increase with the increasing of sulphuric acid concentration and leaching time.The maximum leaching rate of CeO2 and Tb4O7 are 99.66% and 91.69%.The leach of CeO2 and Tb4O7 are very difficult due to tough structure of magnesium aluminate spinel.The leaching rate of CeO2 and Tb4O7 are merely 32.97% and 32.79%.The magnesium aluminate spinel in residue was destroyed by alkali roasting,resulting in significant increase of leaching rate of CeO2 and Tb4O7.The secondary leaching rate of Y2O3,Eu2O3,CeO2,Tb4O7 and the total recovery of REOs are 98.83%,93.71%,81.78%,88.46% and 96.21% correspondingly and respectively.The final leach residue has flocculent loose microstructure.The particle size is about 1 μm ~ 10 μm.Almost no rare earth element presented in leach residue.%采用机械活化浸出的方法从废弃荧光粉中浸出稀土元素,考查了液固比、硫酸浓度、浸出时间对稀土氧化物浸出率的影响,并对浸出渣进行了碱式焙烧—二段浸出.研究结果表明,Y2O3、Eu2O3浸出率随液固比增大略有降低,随硫酸浓度的提高和浸出时间的延长显著提高,最高达99.66%和91.69%;CeO2、Tb4O7浸出率远小于Y2O3、Eu2O3,仅为32.97%和32.79%,其浸出率受到镁铝尖晶石的酸解浸出的影响;碱式焙烧破坏了镁铝尖晶石的结构,显著提高了CeO2、Tb4O7的浸出率,浸出渣中Y2O3、Eu2O3、CeO2 、Tb4O7

  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. 煤矸石酸浸渣-硫酸钠碳热法制备水玻璃的实验研究%Experimental Study on the Preparation Water Glass by Carbothermic Method Using Acid Leaching Slag of Coal Gangue and Sodium Sulfate

    Institute of Scientific and Technical Information of China (English)

    自桂芹; 夏举佩; 刘成龙

    2015-01-01

    In order to easily prepare sodium silicate by dry method using coal gangue and sodium sulfate, 98% sulfuric acid as acid medium, silica-rich acid leaching residue is obtained using microwave heating method to extract acid soluble substances from coal gangue. silicon dioxide of acid leaching slag with Sodium oxide of sodium sulfate are mixed according to the modulus of 1.0 to produce low modulus sodium silicate. Coke mass, the calcining temperature, calcining time, cooling method, melting temperature, dissolving time, liquid-solid ratio on the inlfuence of silica dissolution rate are studied. The results show that, under the optimal process conditions: Coke mass is 17.0% of the sodium sulfate, the calcining temperature of 1100℃, the melting time of 1 h, water quenching for cooling, liquid-solid ratio of 10∶1, dissolution temperature of 80℃, dissolution time of 90 min, dissolution rate of silica reaches 72.56%, modulus of liquid water glass is 1.24.%为了便于利用煤矸石酸浸渣-硫酸钠干法制备水玻璃,用98%硫酸作酸浸介质、微波进行辅助加热直接浸取煤矸石中酸溶物,制备富含硅的酸浸渣。按酸浸渣中二氧化硅与硫酸钠中氧化钠摩尔比1.0配料干法生产低模数水玻璃。研究了焦炭量、煅烧温度、煅烧时间、冷却方式、溶解温度、溶解时间、液固比对二氧化硅溶出率的影响。结果表明,最佳工艺条件为:焦炭量为硫酸钠质量的17.0%,煅烧温度1100℃,熔融时间1 h,冷却方式为水淬骤冷,液固质量比为10∶1,溶解温度80℃,溶解时间90 min,此条件下二氧化硅溶出率为72.56%,液体水玻璃模数为1.24。

  10. 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.

  11. 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.

  12. 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.

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

    Science.gov (United States)

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

    2009-07-30

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

  14. Metal removal from Municipal Solid Waste Incineration fly ash: A comparison between chemical leaching and bioleaching.

    Science.gov (United States)

    Funari, V; Mäkinen, J; Salminen, J; Braga, R; Dinelli, E; Revitzer, H

    2017-02-01

    Bio- and hydrometallurgical experimental setups at 2-l reactor scale for the processing of fly ash from municipal waste incinerators were explored. We aimed to compare chemical H2SO4 leaching and bioleaching; the latter involved the use of H2SO4 and a mixed culture of acidophilic bacteria. The leaching yields of several elements, including some of those considered as critical (Mg, Co, Ce, Cr, Ga, Nb, Nd, Sb and Sm), are provided. At the end of the experiments, both leaching methods resulted in comparable yields for Mg and Zn (>90%), Al and Mn (>85%), Cr (∼65%), Ga (∼60%), and Ce (∼50%). Chemical leaching showed the best yields for Cu (95%), Fe (91%), and Ni (93%), whereas bioleaching was effective for Nd (76%), Pb (59%), and Co (55%). The two leaching methods generated solids of different quality with respect to the original material as we removed and significantly reduced the metals amounts, and enriched solutions where metals can be recovered for example as mixed salts for further treatment. Compared to chemical leaching the bioleaching halved the use of H2SO4, i.e., a part of agent costs, as a likely consequence of bio-produced acid and improved metal solubility.

  15. 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 < THM < DNT showing strong correlation with increasing aqueous solubility 610 mg/L < 4100 mg/L < 39,830 mg/L. Triplicate column study experiments were conducted to evaluate the consistency of the breakthrough pattern of these 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.

  16. [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.

  17. Two stage leaching of activated spent HDS catalyst and solvent extraction of aluminium using organo-phosphinic extractant, Cyanex 272.

    Science.gov (United States)

    Park, Kyung Ho; Mohapatra, Debasish; Nam, Chul-Woo

    2007-09-05

    Spent catalyst generally contains valuable metals like Mo, Co, Ni on a supporting material, such as gamma-A1(2)O(3). In the present study, a two stage alkali/acid leaching process is proposed to selectively target molybdenum and cobalt/nickel separately to facilitate the downstream processing. Prior to the leaching, the spent catalyst was calcined at 500 degrees C to remove C and S; and to convert metal sulphides to metal oxides. 98% Mo, 93% Co and 90% Ni was effectively recovered by this process. The sulphuric acid leaching of spent catalyst, previously treated by alkali solutions to remove Mo, yielded a solution rich in Ni, Co and Al. In order to recover Co and Ni, the Al impurity must be eliminated. The extraction and stripping of Al has been carried out using the organo-phosphinic extractant, Cyanex 272 diluted in carbon tetrachloride. Quantitative Al extraction efficiency was achieved with 1.0M Cyanex 272 in two stages at an aqueous:organic (A:O) phase ratio of 1:1 and equilibrium pH of 3.2. Complete stripping of Al from the loaded organic was carried out using 2M H(2)SO(4) at an A:O phase ratio of 1:1. The extraction reaction proceeded via the cation exchange mechanism and the extracted species was assumed to be AlA(3).3HA. The extraction of Al was carried out in the presence of various ions to ascertain the tolerance limit of individual ions. The regenerated solvent was successfully used for 8 cycles without any significant loss of extraction efficiency, suggesting that Cyanex 272 is extremely stable under present experimental conditions.

  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. 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.

  20. 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.

  1. Spectroscopic and microscopic characterization of portland cement based unleached and leached solidified waste

    Science.gov (United States)

    Salaita, Ghaleb N.; Tate, Philip H.

    1998-05-01

    In this study, portland cement based solidified/stabilized (S/S) waste and a cement-only control were studied before and after leaching. The solidified waste samples were prepared from a mix of organic-containing industrial waste sludge and portland cement. Toxicity characterization leaching procedure (TCLP) was the leaching test employed. The samples were studied using multi-surface analytical techniques including XPS, SIMS, XRD, FE-SEM and EDS. The data obtained from the various techniques show that leaching does not measurably affect the morphology or composition of the solidified waste sample. However, subtle changes in the composition of the cement control sample were observed. While the concentration of the elements observed on the surface of leached and unleached waste samples by XPS are very similar (except for Mg, Na and N), study of the corresponding cement samples exhibit differences in the level of C, Si, S, and Ca. The unleached cement sample shows lower levels of C and Si, but higher levels of O, S, Ca and Mg, indicating that leaching alters the cement sample. EDS analyses of the elemental composition of the bulk of the leached and unleached waste samples are similar, and also are similar for the leached and unleached cement samples, indicating that under the conditions of the TCLP test, leaching has no effect on the bulk. The high level of Ca present on the surface of the solidified waste indicates entrapment of the waste by the cement. The information and results obtained show that the surface analytical techniques used in this work, when combined with environmental wet methods, can provide a more complete picture of the concentration, chemical state and immobility of solidified waste.

  2. 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

  3. 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%.

  4. The biological effects of magnesium-leached chrysotile asbestos.

    Science.gov (United States)

    Morgan, A.; Davies, P.; Wagner, J. C.; Berry, G.; Holmes, A.

    1977-01-01

    Chrysotile asbestos was leached in N hydrochloric acid for varying times to produce a range of magnesium-depleted samples. The protein adsorptive capacity, the haemolytic activity, and the capacity to cause selective release of acid hydrolases from macrophages were measured for the various samples in vitro. The carcinogenicity of the same materials was determined following intrapleural inoculation in rats. The adsorptive capacity for albumin decreased linearly with magnesium removal. The haemolytic activity also declined until about half the magnesium had been removed, after which there was little further change. The selective release of acid hydrolases from macrophages in culture increased up to the point at which half the magnesium had been removed but by 90% depletion had declined rapidly. The carcinogenicity of 50% -depleted chrysotile was similar to that of intact, but at 90% depletion the incidence of mesothelial tumours had fallen considerably. There was no evidence that the leached samples fragmented more than the unleached in vivo. Images Fig. 1 PMID:588440

  5. 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.

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

    Science.gov (United States)

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

    2015-11-01

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

  7. Effects of iron oxidizing bacteria in thiourea leaching of gold ores

    OpenAIRE

    甲斐, 敬美; 山崎, 研市; 高橋, 武重; カイ, タカミ; ヤマサキ, ケンイチ; タカハシ, タケシゲ; KAI, Takami; YAMASAKI, Kenichi; Takahashi, Takeshige

    1991-01-01

    Bacterial leaching was combined with thiourea method for the gold leaching from ores. For gold bearing pyrites, biological pre-oxidation has been generally perfomed. In the present study, we carried out the biological treatment to the high silicate bearing ores by using the iron oxidizing bacteria, Thiobacillus ferrooxidans. The recovery of gold and silver was enhanced by the biological pretreatment, while the effects of the treatment was influenced by the types of gold ores. Since the biolog...

  8. 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.

  9. 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.

  10. 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.

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

    Directory of Open Access Journals (Sweden)

    Bolat Uralbekov

    2015-09-01

    Full Text Available 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 concentration in the pregnant leach solution. It has been shown that the uranium in pregnant solutions appears by dissolution of calcium and magnesium carbonates and uranium minerals as well. It was found the decreasing of filtration coefficient from 0.099 m day-1 to 0.082 m day-1, due to the presence of mechanical and chemical mudding. Partial extraction of uranium (85% from the ore has been explained by the slow diffusion of sulfuric acid to the uranium minerals locates in the cracks of silicate minerals. It was concluded that the studied uranium ore sample according to adverse geotechnical parameters is not suitable for uranium extraction by filtration leaching.

  12. Process for the separation and recovery of palladium and platinum from spent automobile catalyst leach liquor using LIX 84I and Alamine 336.

    Science.gov (United States)

    Reddy, B Ramachandra; Raju, B; Lee, Jin Young; Park, Hyung Kyu

    2010-08-15

    Spent catalysts from automobile industry contain environmentally critical and economically valuable metals such as Pt, Pd, Fe, Ni, Mn, and Cr. In this paper, we present a process for the selective separation and complete recovery of palladium (Pd) and platinum (Pt) from hydrochloric acid leach liquors of spent automobile catalyst employing solvent extraction method. Typical composition of leach liquor used for the present study contains (mg/L): Pd-150, Pt-550, Mn-500, Ni-1000, Fe-1500, Cr-100 and 3 M HCl. Selective separation of Pd from the leach liquor is achieved with 0.5 vol.% LIX 84I (2-hydroxy-5-nonylacetophenone oxime in a mixture with a high flash point hydrocarbon diluent) in kerosene at an aqueous to organic (A/O) ratio of 3 in 2 stages, with an enrichment factor of three. Quantitative stripping of Pd from loaded organic is achieved with 0.5 M thiourea and 1 M HCl. Co-extraction of Fe and Pt with 5 vol.% Alamine 336 (tertiary amine of mixed tri-octyl/decyl amine) in kerosene followed by selective scrubbing of Fe with dilute HCl and complete stripping of Pt from loaded organic was proposed with 0.5 M thiourea and 0.1 M HCl. Purity of Pd and Pt strip solutions are 99.7%. Finally, the present process can solve environmental related issues and at the same time recover valuable metals in pure form.

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

    DEFF Research Database (Denmark)

    Hansen, Elly Møller

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

  14. 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.

  15. 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...

  16. Selective leaching of nickel from prereduced limonitic laterite under moderate HPAL conditions- part I: Dissolution

    Directory of Open Access Journals (Sweden)

    Chang Y.

    2016-01-01

    Full Text Available High pressure acid leaching (HPAL is the primary method for extraction of nickel from limonitic laterite. The severe operating conditions, the complexity of facilities, and several technical problems, such as scale formation, have always accompanied the HPAL, however. In this paper, the selective acid leaching of nickel from the pre-reduced limonitic laterite under moderate HPAL conditions was studied. For the calcine with reduction degree of 93.4%, about 88.2% nickel could be selectively extracted at 100°C with an acid/ore ratio of 0.164, leaving less then 5.0g/L iron in the solution. Further increase of leaching temperature, and the ensuing dehydration, transformed goethite in the leaching residue to hematite. When the temperatures were as high as 180°C, the recovery of nickel increased to 95.2%, within one hour, depressing the residual soluble iron to below 1.0g/L (pO2= 1.0 MPa, acid/ore= 0.287.

  17. LEACHING OF CADMIUM, TELLURIUM AND COPPER FROM CADMIUM TELLURIDE PHOTOVOLTAIC MODULES.

    Energy Technology Data Exchange (ETDEWEB)

    FTHENAKIS,V.

    2004-02-03

    Separating the metals from the glass is the first step in recycling end-of-life cadmium telluride photovoltaic modules and manufacturing scrap. We accomplished this by leaching the metals in solutions of various concentrations of acids and hydrogen peroxide. A relatively dilute solution of sulfuric acid and hydrogen peroxide was found to be most effective for leaching cadmium and tellurium from broken pieces of CdTe PV modules. A solution comprising 5 mL of hydrogen peroxide per kg of PV scrap in 1 M sulfuric acid, gave better results than the 12 mL H{sub 2}O{sub 2}/kg, 3.2 M H{sub 2}SO{sub 4} solution currently used in the industry. Our study also showed that this dilute solution is more effective than hydrochloric-acid solutions and it can be reused after adding a small amount of hydrogen peroxide. These findings, when implemented in large-scale operation, would result in significant savings due to reductions in volume of the concentrated leaching agents (H{sub 2}SO{sub 4} and H{sub 2}O{sub 2}) and of the alkaline reagents required to neutralize the residuals of leaching.

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

    Science.gov (United States)

    Bayat, Belgin; Sari, Bulent

    2010-02-15

    The purpose of the study described in this paper was to evaluate the application of bioleaching technique involving Acidithiobacillus ferrooxidans to recover heavy metals (Zn, Cu, Ni, Pb, Cd and Cr) in dewatered metal plating sludge (with no sulfide or sulfate compounds). The effect of some conditional parameters (i.e. pH, oxidation-reduction potential (ORP), sulfate production) and operational parameters (i.e. pulp density of the sludge and agitation time) were investigated in a 3l completely mixed batch (CMB) reactor. The metal recovery yields in bioleaching were also compared with chemical leaching of the sludge waste using commercial inorganic acids (sulfuric acids and ferric chloride). The leaching of heavy metals increased with decreasing of pH and increasing of ORP and sulfate production during the bioleaching experiment. Optimum pulp density for bioleaching was observed at 2% (w/v), and leaching efficiency decreased with increasing pulp density in bioleaching experiments. Maximum metal solubilization (97% of Zn, 96% of Cu, 93% of Ni, 84% of Pb, 67% of Cd and 34% of Cr) was achieved at pH 2, solids contents of 2% (w/v), and a reaction temperature of 25+/-2 degrees C during the bioleaching process. The maximum removal efficiencies of 72% and 79% Zn, 70% and 75% Cu, 69% and 73% Ni, 57% and 70% Pb, 55% and 65% Cd, and 11% and 22% Cr were also attained with the chemical leaching using sulfuric acids and ferric chloride, respectively, at pH 2, solids contents of 2% (w/v), and a reaction temperature of 25+/-2 degrees C during the acid leaching processes. The rates of metal leaching for bioleaching and chemical leaching are well described by a kinetic equation related to time. Although bioleaching generally requires a longer period of operation compared to chemical leaching, it achieves higher removal efficiency for heavy metals. The efficiency of leaching processes can be arranged in descending order as follows: bioleaching>ferric chloride leaching>sulfuric acid

  19. 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.

  20. 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.

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

    Science.gov (United States)

    Chandra, Anand P.; Gerson, Andrea R.

    2011-11-01

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

  2. Reduction of Ash Content in Raw Coal Using Acids and Alkali

    Directory of Open Access Journals (Sweden)

    K. H. Shivaprasad

    2010-01-01

    Full Text Available Ash, an inorganic matter present in coal is amenable for dissolution using suitable reagents. Thus the dissolution of ash and its subsequent removal reduces the release of many toxic elements into the environment by coal based industries. Removal of ash also enhances the calorific value. In the present investigation an attempt has been made to reduce the ash content of raw coal obtained from nearest thermal power by using hydrochloric acid, sulfuric acid and sodium hydroxide. A series of leaching experiments were conducted on coal of different size fractions by varying the parameters like concentration, temperature and time of leaching. The results indicate that it is possible to remove nearly 75% of ash from coal sample by leaching.

  3. Behavior of calcium silicate in leaching process

    Institute of Scientific and Technical Information of China (English)

    刘桂华; 李小斌; 彭志宏; 周秋生

    2003-01-01

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

  4. Kinetics of Leaching Calcium from Dolomite

    Directory of Open Access Journals (Sweden)

    Azizi, A.

    2011-06-01

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

  5. 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

  6. Management practices for minimising nitrate leaching after ploughing temporary leguminous pastures in Canterbury, New Zealand

    Science.gov (United States)

    Francis, G. S.

    1995-12-01

    Winter leaching losses of nitrate following the ploughing of temporary leguminous pastures in late summer or early autumn are a major concern in mixed cropping rotations on the Canterbury Plains of New Zealand. Field experiments showed that pastures ploughed in early autumn (March) and left fallow accumulated 107-142 kg ha -1 N of mineral-N in the soil profile by the start of winter, with 72-106 kg ha -1 N lost through leaching in the first winter. Delaying the ploughing of pasture until late autumn (May) reduced the accumulation of mineral-N to 42-120 kg ha -1 N and the leaching loss to 8-52 kg ha -1 N. In situations where early cultivation cannot be avoided, growing winter cover crops or using the nitrification inhibitor dicyandiamide (DCD) both have the potential to reduce leaching compared with fallow soil. DCD increased the amount of mineral-N present in the soil as ammonium and reduced leaching losses by 25-50% without affecting the yield of the following spring wheat crop. Cover crops only reduced leaching losses (by up to 60%) when they were sown early in the autumn and they had taken up considerable amounts of soil mineral-N before drainage occurred. When cover crops were grazed before incorporation in spring, there was an increased risk of leaching from urine patch areas. If residues were incorporated without grazing, however, the yield of the following spring wheat crop was depressed by 20-30% due to extensive net N immobilization during decomposition of the residues. In Canterbury conditions, the most reliable way to minimise N leaching losses is to delay the ploughing of pasture for as long as possible in autumn or winter. Where pastures are ploughed early, the relative effectiveness of using DCD or growing winter cover crops varies mainly in relation to rainfall distribution.

  7. Interfacial interaction of bio-leaching of pyrite mineral

    Institute of Scientific and Technical Information of China (English)

    GU Guo-hua; WANG nui; SUO Jun; QIU Guan-zhou; HAO Ye

    2008-01-01

    Electrokinetic and contact angle measurements were used to discuss the interracial interaction on bio-leaching of pyrite mineral. Surface energy parameters of pyrite mineral and thiobaeillus ferrooxidans were Gbtained by calculating according to formula of Young's equation and contact angle measurements. The results show that surface energy of thiobacillus ferrooxidans is much higher than that of pyrite mineral, and the reaction of pyrite mineral with thiobacillus ferrooxidans causes the reduction of the pyrite surface energy. The interfacial interaction energies between pyrite mineral and thiobacillus ferrooxidans were also obtained based onpolar interfacial interaction theory and electrokinetic and contact angle measurements. The thermodynamics approach only considering Lifshitz-van der Waals and Lewis acid-base interaction fails to explain the adhesion behavior of the bacteria, but theextended Derjaguin-Landan-Verwey-Overbeek theory concerning Lifshitz-van der Waals and Lewis acid-base and the electrostatic can exactly predict interracial interaction.

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

    Institute of Scientific and Technical Information of China (English)

    孟宇群; 吴敏杰; 宿少玲; 王隆保

    2003-01-01

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

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

    Science.gov (United States)

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

    2016-09-15

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

  10. Dynamic simulation of the carbon-in-pulp and carbon-in-leach processes

    Directory of Open Access Journals (Sweden)

    L. R. P. de Andrade Lima

    2007-12-01

    Full Text Available Carbon-in-leach and carbon-in-pulp are continuous processes that use activated carbon in a cascade of large agitated tanks, which have been widely used to recover or concentrate precious metals in gold extraction plants. In the carbon-in-pulp process adsorption occurs after the leaching cascade section of the plant, and in the carbon-in-leach process leaching and adsorption occur simultaneously. In both processes the activated carbon is moved from one tank to another in countercurrent with the ore pulp until the recovery of the loaded carbon in the first tank. This paper presents a dynamic model that describes, with minor changes, the carbon-in-leach, the carbon-in-pulp, and the gold leaching processes. The model is numerically solved and calibrated with experimental data from a plant and used to perform a study of the effect of the activated carbon transfer strategy on the performance of the adsorption section of the plant. Based on the calculated values of the gold loss in the liquid and of the gold recovered in the loaded activated carbon that leaves the circuit, the results indicate that strategies in which a significant amount of activated carbon is held in the first tank and the contact time between the carbon and the pulp is longer are the best carbon transfer strategies for these processes.

  11. Users' guide for the Accelerated Leach Test Computer Program

    Energy Technology Data Exchange (ETDEWEB)

    Fuhrmann, M.; Heiser, J.H.; Pietrzak, R.; Franz, Eena-Mai; Colombo, P.

    1990-11-01

    This report is a step-by-step guide for the Accelerated Leach Test (ALT) Computer Program developed to accompany a new leach test for solidified waste forms. The program is designed to be used as a tool for performing the calculations necessary to analyze leach test data, a modeling program to determine if diffusion is the operating leaching mechanism (and, if not, to indicate other possible mechanisms), and a means to make extrapolations using the diffusion models. The ALT program contains four mathematical models that can be used to represent the data. The leaching mechanisms described by these models are: (1) diffusion through a semi-infinite medium (for low fractional releases), (2) diffusion through a finite cylinder (for high fractional releases), (3) diffusion plus partitioning of the source term, (4) solubility limited leaching. Results are presented as a graph containing the experimental data and the best-fit model curve. Results can also be output as LOTUS 1-2-3 files. 2 refs.

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

    Science.gov (United States)

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

    2017-02-01

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

  13. Reductive Leaching of Iron from Sulfate Slag%硫酸烧渣还原浸取铁

    Institute of Scientific and Technical Information of China (English)

    金程; 李登新

    2012-01-01

    采用硫化物作助剂还原浸出硫酸烧渣中的三价铁.采用L9(43)四因素三水平正交试验,考察助剂用量、硫酸用量、温度、时间对浸出效果的影响,并确定最佳配比.结果表明:影响的显著顺序为助剂用量>时间>硫酸用量>温度.在下述最佳条件下铁浸取率可以达到87.8%:起始液固比2∶1、搅拌转速1 300 r/min、助剂用量17.2g、硫酸23 mL、85℃反应3h.%The ferric iron was reductive leached from sulfate slag with sulfide. The effects of leaching agent dosage, sulfuric acid consumption, reaction temperature and time on leaching rate of iron were investigated with L9(43) orthogonal test. The results show that the sequence of effecting is leaching agent dosage, reaction time, sulfuric acid consumption and reaction temperature. The iron leaching rate reaches 87. 8% on the following optimum conditions: ratio of liquid to solid of 2 : 1, stirring rate of 1 300 r/min, leaching a-gent dosage of 17. 2 g, sulfuric acid consumption of 23 mL, leaching temperature of 85 °C and leaching time of 3 h.

  14. Research on Li4SiO4 Prepared from the Residue of Serpentine after Extracting Magnesium by Acid Leaching%蛇纹石酸浸提镁残渣制备硅酸锂及其性能研究

    Institute of Scientific and Technical Information of China (English)

    李春全; 狄永浩; 赵德偲; 郑水林; 牛保军

    2015-01-01

    以蛇纹石酸浸提镁残渣为硅源,碳酸锂为锂源,通过高温固相反应合成了硅酸锂高温固碳材料,探究了煅烧时间、气氛以及物料配比对合成材料高温固碳性能的影响。采用热重-差热综合热分析仪(TG-DTG)研究了蛇纹石酸浸提镁残渣型硅酸锂的CO2吸收性能,并通过扫描电子显微镜(SEM)与X射线衍射仪(XRD)对合成材料的微观形貌与结构特征进行了表征。结果表明:蛇纹石酸浸提镁残渣型硅酸锂具有较好的CO2吸收性能,吸收量可达26.66%;与市售SiO2为硅源相比,蛇纹石酸浸提镁残渣型硅酸锂材料煅烧合成时间缩短,高温固碳性能更优。%Using the residue of acid leaching serpentine after extracting magnesium as the silicon source, and lithium carbonate as the lithium source, lithium silicate, a kind of high-temperature carbon absorption material was synthesized through high temperature solid state reaction. The impact of calcining time, atmosphere and material ratio on the high-temperature carbon absorption properties of synthetic materials were studied in this paper. TG-DTG was applied to study the CO2 absorption properties of lithium silicate which is synthesized by the residue of serpentine after extracting magnesium by acid leaching, and the morphology and structure of synthetic materials were characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD). The results show that:lithium silicate synthesized by the residue of serpentine after extracting magnesium has good CO2 absorption capacity, which can be up to 26.66%. Compared with commercially SiO2 as the silicon source, lithium silicate prepared from the residue of serpentine after extracting magnesium has a lower calcination time, while a better high-temperature carbon sequestration performance.

  15. Leaching techniques to remove metals and potentially hazardous nutrients from trout farm sludge.

    Science.gov (United States)

    Jung, I S; Lovitt, R W

    2011-11-15

    A fish farm sludge high in P (2-6% w/w as dry matter), Fe (5-7%), C (40-50%) and N (0.8-4%) was subjected to a series of acid leaching treatments using HCl, organic acids, and biologically mediated acid production. Additions of biodegradable organic acid solubilized heavy metals better than HCl, while additions of 1.5% w/v glucose followed by 7 day incubation stabilized the sludge releasing 92% P, 100% Fe. The use of homo-lactic Lactobacillus plantarum starter cultures were more effective than hetero-lactic Lactobacillus buchneri, solubilizing 81.9% P, 92.2% Fe, 93.0% Zn and 96.4% Ca in the sludge. The anaerobic sludge-glucose fermentation using L. plantarum produced a leached sludge that has low heavy metal and nutrient content while affording the recovery of nutrients. The potential of these methods for practical application are briefly discussed.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2015-04-15

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

  17. Superparamagnetic poly(methyl methacrylate) nanoparticles surface modified with folic acid presenting cell uptake mediated by endocytosis

    Science.gov (United States)

    Feuser, Paulo Emilio; Jacques, Amanda Virtuoso; Arévalo, Juan Marcelo Carpio; Rocha, Maria Eliane Merlin; dos Santos-Silva, Maria Claudia; Sayer, Claudia; de Araújo, Pedro H. Hermes

    2016-04-01

    The encapsulation of superparamagnetic nanoparticles (MNPs) in polymeric nanoparticles (NPs) with modified surfaces can improve targeted delivery and induce cell death by hyperthermia. The goals of this study were to synthesize and characterize surface modified superparamagnetic poly(methyl methacrylate) with folic acid (FA) prepared by miniemulsion polymerization (MNPsPMMA-FA) and to evaluate their in vitro cytotoxicity and cellular uptake in non-tumor cells, murine fibroblast (L929) cells and tumor cells that overexpressed folate receptor (FR) β, and chronic myeloid leukemia cells in blast crisis (K562). Lastly, hemolysis assays were performed on human red blood cells. MNPsPMMA-FA presented an average mean diameter of 135 nm and a saturation magnetization (Ms) value of 37 emu/g of iron oxide, as well as superparamagnetic behavior. The MNPsPMMA-FA did not present cytotoxicity in L929 and K562 cells. Cellular uptake assays showed a higher uptake of MNPsPMMA-FA than MNPsPMMA in K562 cells when incubated at 37 °C. On the other hand, MNPsPMMA-FA showed a low uptake when endocytosis mechanisms were blocked at low temperature (4 °C), suggesting that the MNPsPMMA-FA uptake was mediated by endocytosis. High concentrations of MNPsPMMA-FA showed hemocompatibility when incubated for 24 h in human red blood cells. Therefore, our results suggest that these carrier systems can be an excellent alternative in targeted drug delivery via FR.

  18. Inorganic-organic hybrids originating from organosilane anchored onto leached vermiculite

    Directory of Open Access Journals (Sweden)

    Ana P. M. Alves

    2013-01-01

    Full Text Available The reactivity of clay minerals leached in grafting reactions was investigated. Precursor solids were prepared by treating the sodium vermiculites with nitric acid solutions at several concentrations. The lixiviation produced the restructured porous solids with surface area over a wide range, varying from 133 to 673 m² g- 1. The sodium and lixiviated vermiculites reacted covalently with silylating agent, 3-aminopropyltrimethoxysilane, to attach this agent onto the inorganic surface, through the free available silanols. The products were characterized by CNH elemental analysis, infrared spectroscopy, X-ray diffraction, nuclear magnetic resonance in the solid state for carbon and silicon. CHN data expressed by significant contents of anchored organic chains, up to 2.14 mmol g- 1, as the degree of leaching was increased. The success of this investigation is directly related to the leaching of the natural vermiculite, which is strongly influenced by the reactivity of the abundant original source.

  19. Plant Biomass Leaching for Nutrient Recovery in Closed Loop Systems Project

    Science.gov (United States)

    Zeitlin, Nancy P.; Wheeler, Raymond (Compiler); Lunn, Griffin

    2015-01-01

    Plants will be important for food and O2 production during long term human habitation in space. Recycling of nutrients (e.g., from waste materials) could reduce the resupply costs of fertilizers for growing these plants. Work at NASA's Kennedy Space Center has shown that ion exchange resins can extract fertilizer (plant essential nutrients) from human waste water, after which the residual brine could be treated with electrodialysis to recover more water and produce high value chemicals (e.g., acids and bases). In habitats with significant plant production, inedible biomass becomes a major source of solid waste. To "close the loop" we also need to recover useful nutrients and fertilizer from inedible biomass. We are investigating different approaches to retrieve nutrients from inedible plant biomass, including physical leaching with water, processing the biomass in bioreactors, changing the pH of leaching processing, and/or conducting multiple leaches of biomass residues.

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

    Directory of Open Access Journals (Sweden)

    Lorraine Negron

    2016-02-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2010-05-21

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

  2. Leaching Mechanism of Complicated Antimony-Lead Concentrate and Sulfur Formation in Slurry Electrolysis

    Institute of Scientific and Technical Information of China (English)

    WangChengyan; QiuDingfan; JiangPeihai

    2004-01-01

    Anodic reaction mechanism of complicated antimony-lead concentrate in slurry electrolysis was investigated by the anodic polarization curves determined under various conditions. The main reactions on the anode are the oxidations of FeCln(2-n) . Though the oxidation of jamesonite particle on the anode can occur during the whole process, it is less. With the help of mineralogy studies and relevant tests, the leaching reaction mechanism of jameson[to and gudmundite during slurry electrolysis was ascertained. Because of the oxidation reaction of FeCl3 produced by antimony-lead concentrate itself, the non-oxidation complex acid dissolution of jameson[re, the oxidation complex acid dissolution of gudmundite, and the oxidation of air carried by stirring, the leaching ratio of antimony reaches about 35% when HCl-NH4Cl solution is used to leach antimony-lead concentrate directly. So when the theoretical electric quantity is given to oxidation of antimony in slurry electrolysis, all of antimony, lead and iron containing in antimony-lead concentrate, are leached. The formation of sulfur is through the directly redox reaction of Fe3+ and jameson[re. The S2- in jamesonite is oxidized into S0 , and forms the crystals of sulfur again on the spot. The redox reaction of Fe3+ and H2S formed by non-oxidative acid dissolution of jamesonite is less.

  3. ALUMINUM AND CHROMIUM LEACHING WORKSHOP WHITEPAPER

    Energy Technology Data Exchange (ETDEWEB)

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

    2007-04-25

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

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

    Institute of Scientific and Technical Information of China (English)

    赵由才; R.Stanforth

    2004-01-01

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

  5. Geochemical association of Pu and Am in selected host-phases of contaminated soils from the UK and their susceptibility to chemical and microbiological leaching.

    Science.gov (United States)

    Kimber, Richard L; Corkhill, Claire L; Amos, Sean; Livens, Francis R; Lloyd, Jonathan R

    2015-04-01

    Understanding the biogeochemical behaviour and potential mobility of actinides in soils and groundwater is vital for developing remediation and management strategies for radionuclide-contaminated land. Pu is known to have a high Kd in soils and sediments, however remobilization of low concentrations of Pu remains a concern. Here, some of the physicochemical properties of Pu and the co-contaminant, Am, are investigated in contaminated soils from Aldermaston, Berkshire, UK, and the Esk Estuary, Cumbria, UK, to determine their potential mobility. Sequential extraction techniques were used to examine the host-phases of the actinides in these soils and their susceptibility to microbiological leaching was investigated using acidophilic sulphur-oxidising bacteria. Sequential extractions found the majority of (239,240)Pu associated with the highly refractory residual phase in both the Aldermaston (63.8-85.5 %) and Esk Estuary (91.9-94.5%) soils. The (241)Am was distributed across multiple phases including the reducible oxide (26.1-40.0%), organic (45.6-63.6%) and residual fractions (1.9-11.1%). Plutonium proved largely resistant to leaching from microbially-produced sulphuric acid, with a maximum 0.18% leached into solution, although up to 12.5% of the (241)Am was leached under the same conditions. If Pu was present as distinct oxide particles in the soil, then (241)Am, a decay product of Pu, would be expected to be physically retained in the particle. The differences in geochemical association and bioleachability of the two actinides suggest that this is not the case and hence, that significant Pu is not present as distinct particles. These data suggest the majority of Pu in the contaminated soils studied is highly recalcitrant to geochemical changes and is likely to remain immobile over significant time periods, even when challenged with aggressive "bioleaching" bacteria.

  6. Leaching of Main Elements of Glass Immersed in Beishan Groundwater

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    <正>The leaching quantities of the elements from the HLW are very important parameters for the safety assessments of the repository of high level radioactive wastes. It is necessary to study the leaching

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

    Energy Technology Data Exchange (ETDEWEB)

    Katayama, Y.B.

    1979-04-01

    Spent light-water-reactor (LWR) fuels with burnups of 54.5, 28 and 9 MWd/kgU were leach-tested in deionized water at 25/sup 0/C. Fuel burnup has no apparent effect on the calculated leach rates based upon the behavior of /sup 137/Cs and /sup 239 +240/Pu. A leach test of 54.5 MWd/kgU spent fuel in synthetic sea brine showed that the cesium-based leach rate is lower in sea brine than in deionized water. A rise in the leach rate was observed after approximately 600 d of cumulative leaching. During the rise, the leach rate for all the measured radionuclides become nearly equal. Evidence suggests that exposure of new surfaces to the leachant may cause the increase. As a result, experimental work to study leaching mechanisms of spent fuel has been initiated. 22 figures.

  8. Thermal treatment and leaching of biochar alleviates plant growth inhibition from mobile organic compounds

    Directory of Open Access Journals (Sweden)

    Nigel V. Gale

    2016-08-01

    Full Text Available Recent meta-analyses of plant responses to biochar boast positive average effects of between 10 and 40%. Plant responses, however, vary greatly across systems, and null or negative biochar effects are increasingly reported. The mechanisms responsible for such responses remain unclear. In a glasshouse experiment we tested the effects of three forestry residue wood biochars, applied at five dosages (0, 5, 10, 20, and 50 t/ha to a temperate forest drystic cambisol as direct surface applications and as complete soil mixes on the herbaceous pioneers Lolium multiflorum and Trifolium repens. Null and negative effects of biochar on growth were found in most cases. One potential cause for null and negative plant responses to biochar is plant exposure to mobile compounds produced during pyrolysis that leach or evolve following additions of biochars to soil. In a second glasshouse experiment we examined the effects of simple leaching and heating techniques to ameliorate potentially phytotoxic effects of volatile and leachable compounds released from biochar. We used Solid Phase Microextraction (SPME–gas chromatography–mass spectrometry (GC-MS to qualitatively describe organic compounds in both biochar (through headspace extraction, and in the water leachates (through direct injection. Convection heating and water leaching of biochar prior to application alleviated growth inhibition. Additionally, growth was inhibited when filtrate from water-leached biochar was applied following germination. SPME-GC-MS detected primarily short-chained carboxylic acids and phenolics in both the leachates and solid chars, with relatively high concentrations of several known phytotoxic compounds including acetic acid, butyric acid, 2,4-di-tert-butylphenol and benzoic acid. We speculate that variable plant responses to phytotoxic organic compounds leached from biochars may largely explain negative plant growth responses and also account for strongly species

  9. Leaching of toluene-neoprene adhesive wastes.

    Science.gov (United States)

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

    2001-03-01

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

  10. Column leaching from biomass combustion ashes

    DEFF Research Database (Denmark)

    Maresca, Alberto; Astrup, Thomas Fruergaard

    2015-01-01

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

  11. Duality properties of Gorringe Leach equations

    Science.gov (United States)

    Grandati, Yves; Bérard, Alain; Mohrbach, Hervé

    2009-02-01

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

  12. Leaching of Plastic Additives to Marine Organisms

    NARCIS (Netherlands)

    Koelmans, A.A.; Besseling, E.; Foekema, E.M.

    2014-01-01

    It is often assumed that ingestion of microplastics by aquatic species leads to increased exposure to plastic additives. However, experimental data or model based evidence is lacking. Here we assess the potential of leaching of nonylphenol (NP) and bisphenol A (BPA) in the intestinal tracts of Areni

  13. Gold and Silver Extraction from Leach Solutions

    OpenAIRE

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

    2014-01-01

    There has been carried out an investigation on the extraction of gold and silver from thiosulfate solutions: standard test and technological solutions of chemical and electrochemical leaching. The influence of related metals on the process of extracting gold from solution was studied. There has been conducted a comparative study of the IR spectra of solutions after the sorption of gold, silver and related metals.

  14. [Leaching of copper ore of the Udokanskoe deposit at low temperatures by an association of acidophilic chemolithotrophic microorganisms].

    Science.gov (United States)

    Kondrat'eva, T F; Pivovarova, T A; Krylova, L N; Melamud, V S; Adamov, E V; Karavaĭko, G I

    2011-01-01

    Pure cultures of indigenous microorganisms Acidithiobacillus ferrooxidans strain TFUd, Leptospirillum ferrooxidans strain LUd, and Sulfobacillus thermotolerans strain SUd have been isolated from the oxidation zone of sulfide copper ore of the Udokanskoe deposit. Regimes of bacterial-chemical leaching of ore have been studied over a temperature range from -10 to +20 degrees C. Effects of pH, temperature, and the presence of microorganisms on the extraction of copper have been shown. Bacterial leaching has been detected only at positive values of temperature, and has been much more active at +20 than at +4 degrees C. The process of leaching was more active when the ore contained more hydrophilic and oxidized minerals. The possibility of copper ore leaching of the Udokanskoe deposit using sulfuric acid with pH 0.4 at negative values of temperature and applying acidophilic chemolithotrophic microorganisms at positive values of temperature and low pH values was shown.

  15. Fungal leaching of valuable metals from a power plant residual ash using Penicillium simplicissimum: Evaluation of thermal pretreatment and different bioleaching methods.

    Science.gov (United States)

    Rasoulnia, P; Mousavi, S M; Rastegar, S O; Azargoshasb, H

    2016-06-01

    Each year a tremendous volume of V-Ni rich ashes is produced by fuel oil consuming power plants throughout the world. Recovery of precious metals existing in these ashes is very important from both economic and environmental aspects. The present research was aimed at investigating bioleaching potential of Penicillium simplicissimum for the recovery of metals from power plant residual ash (PPR ash) using different bioleaching methods such as one-step, two-step, and spent-medium bioleaching at 1% (w/v) pulp density. Furthermore, the effects of thermal pretreatment on leaching of V, Ni, and Fe, as major elements present in PPR ash, were studied. Thermal pretreatment at various temperatures removed the carbonaceous and volatile fraction of the ash and affected the fungal growth and metal leachability. The highest extraction yields of V and Ni were achieved for the original PPR ash, using spent-medium bioleaching in which nearly 100% of V and 40% of Ni were extracted. The maximum extraction yield of Fe (48.3%) was obtained for the pretreated PPR ash at 400°C by spent-medium bioleaching. In addition, the fungal growth in pure culture was investigated through measurement of produced organic acids via high performance liquid chromatography (HPLC). Chemical leaching experiments were performed, using commercial organic acids at the same concentrations as those produced under optimum condition of fungal growth (5237ppm citric, 3666ppm gluconic, 1287ppm oxalic and 188ppm malic acid). It was found that in comparison to chemical leaching, bioleaching improved V and Ni recovery up to 19% and 12%, respectively. Moreover, changes in physical and chemical properties as well as morphology of the samples utilizing appropriate analytical methods such as XRF, XRD, FTIR, and FE-SEM were comprehensively investigated.

  16. Enhancements of LEACH Algorithm for Wireless Networks: A Review

    Directory of Open Access Journals (Sweden)

    M. Madheswaran

    2013-12-01

    Full Text Available Low Energy Adaptive Clustering Hierarchy (LEACH protocol is the first hierarchical cluster based routing protocol successfully used in the Wireless Sensor Networks (WSN. In this paper, various enhancements used in the original LEACH protocol are examined. The basic operations, advantages and limitations of the modified LEACH algorithms are compared to identify the research issues to be solved and to give the suggestions for the future proposed routing algorithms of wireless networks based on LEACH routing algorithm.

  17. 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

  18. Determination of silver in miscellaneous copper materials in hydrochloric acid medium by ammonia leaching-flame atomic absorption spectrometry%氨水浸取-盐酸介质火焰原子吸收光谱法测定杂铜物料中的银

    Institute of Scientific and Technical Information of China (English)

    肖红新

    2014-01-01

    The sample is dissolved in aqua regia and silver is leached by ammonia ,most other metallic elements are precipitated at the same time ,eliminating the interference .In 10%hydrochloric acid medium ,under the set equip-ment working conditions ,silver content was determined by flame atomic absorption spectrometry .The relatively stand-ard deviation of the determination results is less than 1 %.%采用王水溶解样品,氨水浸取银,同时沉淀分离大部分其他金属元素,消除其他元素干扰;在10%的盐酸介质中,在设定的仪器工作条件下,采用火焰原子吸收光谱法测定杂铜物料中的银。该方法简单快速、准确可靠,测定结果相对标准偏差小于1%。

  19. Chemical ionization mass spectrometry (CIMS may not measure all gas-phase sulfuric acid if base molecules are present

    Directory of Open Access Journals (Sweden)

    T. Kurtén

    2010-12-01

    Full Text Available 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 case, this effect has to be taken into account in the interpretation of atmospheric sulfuric acid measurement data, as well as in intercomparison of different CIMS instruments, which likely have different susceptibilities to amine-sulfuric acid clustering.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    1997-12-31

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

  1. Behavioral and electrophysiological responses of Aedes albopictus to certain acids and alcohols present in human skin emanations.

    Science.gov (United States)

    Guha, Lopamudra; Seenivasagan, T; Iqbal, S Thanvir; Agrawal, O P; Parashar, B D

    2014-10-01

    Human skin emanations attract hungry female mosquitoes toward their host for blood feeding. In this study, we report the flight orientation and electroantennogram response of Aedes albopictus females to certain unsaturated acids and alcohols found in human skin. In the Y-tube olfactometer, odors of lactic acid and 2-methyl-3-pentanol attracted 54-65% of Ae. albopictus females at all doses in a dose-dependent manner. However, at the highest dose (10(-2) g), the acids repelled 40-45% females. Attractancy (ca. 62-68%) at lower doses and repellency (ca. 30-45%) at higher doses were recorded for 3-methyl-3-pentanol and 1-octen-3-ol, while 5-hexen-1-ol, cis-2-hexen-1-ol, and trans 2-hexen-1-ol odor repelled ca. 55-65% of Ae. albopictus females at all doses. Antenna of female Ae. albopictus exhibited a dose-dependent EAG response up to 10(-3) g of L-lactic acid, trans-2-methyl-2-pentenoic acid, 2-octenoic acid, trans-2-hexen-1-ol and 1-octen-3-ol stimulations; however, the highest dose (10(-2) g) caused a little decline in the EAG response. EAG response of 9-10-fold was elicited by lactic acid, 2-octenoic acid, trans-2-hexenoic acid, and 3-methyl-3-pentanol, while cis-2-hexen-1-ol and trans-2-methyl pentenoic acid elicited 1-5-fold responses compared to solvent control. A blend of attractive compounds could be utilized in odor-baited trap for surveillance and repellent molecules with suitable formulation could be used to reduce the biting menace of mosquitoes.

  2. Stability and leaching of cobalt smelter fly ash

    DEFF Research Database (Denmark)

    Vítková, Martina; Hyks, Jiri; Ettler, Vojtěch

    2013-01-01

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

  3. 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

  4. Cleaning of waste smelter slags and recovery of valuable metals by pressure oxidative leaching.

    Science.gov (United States)

    Li, Yunjiao; Perederiy, Ilya; Papangelakis, Vladimiros G

    2008-04-01

    Huge quantities of slag, a waste solid product of pyrometallurgical operations by the metals industry are dumped continuously around the world, posing a potential environmental threat due to entrained values of base metals and sulfur. High temperature pressure oxidative acid leaching of nickel smelter slags was investigated as a process to facilitate slag cleaning and selective dissolution of base metals for economic recovery. Five key parameters, namely temperature, acid addition, oxygen overpressure, solids loading and particle size, were examined on the process performance. Base metal recoveries, acid and oxygen consumptions were accurately measured, and ferrous/ferric iron concentrations were also determined. A highly selective leaching of valuable metals with extractions of >99% for nickel and cobalt, >97% for copper, >91% for zinc and metals, hematite and virtually zero sulfidic sulfur seems to be suitable for safe disposal. The process seems to be able to claim economic recovery of base metals from slags and is reliable and feasible.

  5. Static leaching of uraniferous shales with countercurrent circuits; Lixiviacion estatica, en contracorriente, de pizarras uraniferas

    Energy Technology Data Exchange (ETDEWEB)

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

    1973-07-01

    We test different amounts of acid and the way of adding it in order to obtain the solubilization of uranium in static leaching. We also test the effects of the temperature. Finally we show the tests of solvent extraction considering the most important variables in it . In leaching we must work with 32 kg/t of acid and 40 d in order to obtain uraniums solubilization over 80%, The pregnant liquors have a high concentration of silica and we must use low organic liquid ( {<=} 3,5 % in amine) and fit the acidity of the pregnant Solutions to 4-8 g H{sub 2}SO{sub 4}/I. We show the economy of the process. (Author)

  6. Isolation and Characterization of Alfalfa-Nodulating Rhizobia Present in Acidic Soils of Central Argentina and Uruguay

    OpenAIRE

    1999-01-01

    We describe the isolation and characterization of alfalfa-nodulating rhizobia from acid soils of different locations in Central Argentina and Uruguay. A collection of 465 isolates was assembled, and the rhizobia were characterized for acid tolerance. Growth tests revealed the existence of 15 acid-tolerant (AT) isolates which were able to grow at pH 5.0 and formed nodules in alfalfa with a low rate of nitrogen fixation. Analysis of those isolates, including partial sequencing of the genes enco...

  7. Effects of Alumina Cement on the Refractory Properties of Leached Ipetumodu Clay

    Directory of Open Access Journals (Sweden)

    Davies Oladayo FOLORUNSO

    2012-08-01

    Full Text Available The effect of alumina cement (Fe2O3 on the refractory properties of leached Ipetumodu clay has been studied. The raw clay was analysed using Scanning Electron Microscope (XL 30 ESEM/EDX, X-Ray Diffraction Machine (Philips PW 3710 with PW 1752 graphite monocromator and X-Ray Fluorescence Machine (ARL 8410 in order to determine the purity level. The tests revealed an average of 5.7% Fe2O3 in the clay. The clay was then purified hydrometallurgical using different concentrations of oxalic acid (0.4, 0.8, 1.2, 1.6 and 2.0 mol/dm3 and combination of different times (30, 60, 90, 120 and 150 min, temperatures (30, 50, 70 and 90ºC and agitation speeds (120, 160, 200 and 240 rev/min. The purification process as revealed by Atomic Absorption Spectrophotometry showed that Fe2O3 was reduced to 0.96%. Samples of leached clay containing different quantities of alumina cement, silica sand and sawdust were prepared, dried at 110ºC for 24 hours and fired at 900, 1100, 1300 and 1500ºC at rate of 4ºC /min, soaked for 2 hrs. These samples were presented for refractory tests (permanent linear change, refractoriness under load, thermal shock resistance, modulus of rupture, bulk density, cold crushing strength and apparent porosity. For all the properties tested, 3% sawdust, 20% silica sand and 10% alumina addition gave the optimum result with reliable phase integrity, as revealed by scanning electron microscopy.

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

    Science.gov (United States)

    Yu, Chao Wei

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

  9. Process development for recovery of copper and precious metals from waste printed circuit boards with emphasize on palladium and gold leaching and precipitation.

    Science.gov (United States)

    Behnamfard, Ali; Salarirad, Mohammad Mehdi; Veglio, Francesco

    2013-11-01

    A novel hydrometallurgical process was proposed for selective recovery of Cu, Ag, Au and Pd from waste printed circuit boards (PCBs). More than 99% of copper content was dissolved by using two consecutive sulfuric acid leaching steps in the presence of H2O2 as oxidizing agents. The solid residue of 2nd leaching step was treated by acidic thiourea in the presence of ferric iron as oxidizing agent and 85.76% Au and 71.36% Ag dissolution was achieved. The precipitation of Au and Ag from acidic thiourea leachate was investigated by using different amounts of sodium borohydride (SBH) as a reducing agent. The leaching of Pd and remained gold from the solid reside of 3rd leaching step was performed in NaClO-HCl-H2O2 leaching system and the effect of different parameters was investigated. The leaching of Pd and specially Au increased by increasing the NaClO concentration up to 10V% and any further increasing the NaClO concentration has a negligible effect. The leaching of Pd and Au increased by increasing the HCl concentration from 2.5 to 5M. The leaching of Pd and Au were endothermic and raising the temperature had a positive effect on leaching efficiency. The kinetics of Pd leaching was quite fast and after 30min complete leaching of Pd was achieved, while the leaching of Au need a longer contact time. The best conditions for leaching of Pd and Au in NaClO-HCl-H2O2 leaching system were determined to be 5M HCl, 1V% H2O2, 10V% NaClO at 336K for 3h with a solid/liquid ratio of 1/10. 100% of Pd and Au of what was in the chloride leachate were precipitated by using 2g/L SBH. Finally, a process flow sheet for the recovery of Cu, Ag, Au and Pd from PCB was proposed.

  10. Simultaneous leaching of Pt, Pd and Rh from automotive catalytic converters in chloride-containing solutions

    Science.gov (United States)

    Hasani, M.; Khodadadi, A.; Koleini, S. M. J.; Saeedi, A. H.; Meléndez, A. M.

    2017-01-01

    Dissolution of platinum group metals (PGM; herein Pt, Pd and Rh) in different chloride-based leaching systems from spent auto catalysts was performed. Response surface methodology and a five-level-five-factor central composite design were used to evaluate the effects of 1) temperature, 2) liquid-to-solid ratio, 3) stirring speed, 4) acid concentration and 5) particle size on extraction yield of PGM by aqua regia. Analysis of variance was used to determine the optimum conditions and most significant factors affecting the overall metal extraction. In the optimum conditions, leaching of Pt, Pd and Rh was 91.58%, 93.49% and 60.15%, respectively. The effect of different oxidizing agents on the PGM dissolution in chloride medium was studied comparatively in the following leaching systems: a) aqua regia/sulfuric acid mixture, b) hydrogen peroxide in sulfuric acid (piranha solution), c) sodium hypochlorite and d) copper(II). Dissolution of Rh is increased in both aqua regia and hydrogen peroxide/hydrochloric acid solutions by adding sulfuric acid.

  11. 盐酸介质磷钒钼黄直接光度法快速测定钒浸出液中的磷%Rapid phosphorus analysis in vanadium- leached solution using direct absorbance measurement in hydrochloric acid media phosphorus - vanadium - molybdenum yellow system

    Institute of Scientific and Technical Information of China (English)

    刘继宁; 马庆; 刘忠文; 党岚

    2001-01-01

    Compared with analytical characteristics and interfering factors for different media, hydrochloric acid was chosen as media in direct absorbance measurement to analyse phosphorus of Vanadium - leached solution.In this method, ammonium sodium was chosen as chromogenic agent, under the conditions that: the coloration acidity is 1.2 N, λ = 430 nm, ε = 1 300. We concluded that when phosphorus content is between 0 ~ 400 μg,Beer' s law is obeyed; when phosphorus content is lower limit 1.67 μg(3s), the coexistence components don' t interfere with phosphorus; when phosphorus content is 50 ~ 350 μg, the adding standard sample rate of recovery is 97.76% ~ 102. 1%; when phosphorus content is 100 μg, eleven times analyses are made and given. RSD =1.52% and X = 100. 48 μ-g.%研究了不同介质中钒钼黄法的分析特性和干扰因素,选定盐酸介质建立了快速分析钒浸出液中磷的直接光度法.该方法用钼酸钠作显色剂,显色酸度1.2 N,λ=430 nm,ε=1300,0~400μg线性良好;检测下限1.67μg(3s),共存组分无干扰,50~350μg加标回收率97.6%~102.1%,100μg中重复11次分析,RSD=1.52%,X=100.48μg.

  12. Remediation of metal polluted hotspot areas through enhanced soil washing--evaluation of leaching methods.

    Science.gov (United States)

    Fedje, Karin Karlfeldt; Yillin, Li; Strömvall, Ann-Margret

    2013-10-15

    Soil washing offers a permanent remediation alternative for metal polluted sites. In addition, the washed out metals can be recovered from the leachate and re-introduced into the social material cycle instead of landfilled. In this paper, soil, bark and bark-ash washing was tested on four different metal polluted soil and bark samples from hotspots at former industrial sites. Six different leaching agents; HCl, NH4Cl, lactic acid, EDDS and two acidic process waters from solid waste incineration, were tested, discussed and evaluated. For the soil washing processes, the final pH in the leachate strongly influences the metal leachability. The results show that a pH leaching yield, while metals were leached when the pH was higher than 2 or below 10. The acidic process waste waters were generally the most efficient at leaching metals from all the samples studied, and as much as 90-100 w% of the Cu was released from some samples. Initial experiments show that from one of these un-purified leachates, Cu metal (>99% purity) could be recovered. After a single leaching step, the metal contents of the soil residues still exceed the maximum limits according to the Swedish guidelines. An additional washing step is needed to reduce the contents of easy soluble metal compounds in the soil residues. The overall results from this study show that soil and bark-ash washing followed by metal recovery is a promising on-site permanent alternative to remediate metal polluted soils and to utilize non-used metal resources.

  13. Leaching of heavy metals from contaminated soils: an experimental and modeling study.

    Science.gov (United States)

    Dijkstra, Joris J; Meeussen, Johannes C L; Comans, Rob N J

    2004-08-15

    In this paper, we characterize the leaching of heavy metals (Ni, Cu, Zn, Cd, and Pb) from eight contaminated soils over a wide range of pH (pH 0.4-12) using an original approach based on batch pH-static leaching experiments in combination with selective chemical extractions and geochemical modeling. The leached concentrations of the heavy metals are generally much lower than the total concentrations and show a strong pH dependency, resulting in "V-shaped" leaching curves with orders of magnitude changes in solution concentrations. The "multisurface" model used incorporates adsorption to dissolved and solid organic matter (NICA-Donnan), iron/aluminum (hydr)oxide (generalized two-layer model) and clay (Donnan model). These models were applied without modifications, and only the standard set of binding constants and parameters was used (i.e., without any fitting). The model predictions of heavy metal leaching are generally adequate and sometimes excellent. Results from speciation calculations are consistent with the well-recognized importance of organic matter as the dominant reactive solid phase in soils. The observed differences between soils with respect to element speciation in the solid phase correspond to the relative amounts of the reactive surfaces present in the soils. In the solution phase, complexes with dissolved organic matter (DOM) are predominant over most of the pH range. Free metal ions (Me2+) are generally the dominant species below pH 4. The combination of the experimental and modeling approach as used in this study is shown to be promising because it leads to a more fundamental understanding of the pH-dependent leaching processes in soils. The "multisurface" modeling approach, with the selected sorption models, is shown to be able to adequately predict the leaching of heavy metals from contaminated soils over a wide range of conditions, without any fitting of parameters.

  14. Suitability of leaching test methods for fly ash and slag: A review

    Directory of Open Access Journals (Sweden)

    Manoj Kumar Tiwari

    2015-10-01

    Full Text Available Fly ash and slag leachate pollution can be of great environmental concern due to generation of these wastes in huge quantities from their respective industrial units, mainly coal-based thermal power plants and iron and steel plants. For simulation of natural leaching in laboratory, various leaching methods are available, but selection of a method that can exactly simulate the real-life scenario for accurate estimation of various pollutants is challenging; particularly, the heavy metals present and impact due to reuse or disposal of these wastes. For choosing the most suitable leaching method according to specific situation, one must primarily consider the chemical and physical properties of wastes, the composition of the source, age of waste disposal, and the climatic conditions of the disposal area. Since these factors may not be specified, a variety of leaching methods with relevant equipment have been proposed by researchers; that are based on their required information to particular conditions in absence of a prescribed protocol and non standardization of equipment. The present review is an attempt to investigate the suitable leaching method for coal fly ash and slag.

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

    Institute of Scientific and Technical Information of China (English)

    周雍茂; 胡宝磊

    2012-01-01

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

  16. Surface modifications on InAs decrease indium and arsenic leaching under physiological conditions

    Science.gov (United States)

    Jewett, Scott A.; Yoder, Jeffrey A.; Ivanisevic, Albena

    2012-11-01

    Devices containing III-V semiconductors such as InAs are increasingly being used in the electronic industry for a variety of optoelectronic applications. Furthermore, the attractive chemical, material, electronic properties make such materials appealing for use in devices designed for biological applications, such as biosensors. However, in biological applications the leaching of toxic materials from these devices could cause harm to cells or tissue. Additionally, after disposal, toxic inorganic materials can leach from devices and buildup in the environment, causing long-term ecological harm. Therefore, the toxicity of these materials along with their stability in physiological conditions are important factors to consider. Surface modifications are one common method of stabilizing semiconductor materials in order to chemically and electronically passivate them. Such surface modifications could also prevent the leaching of toxic materials by preventing the regrowth of the unstable surface oxide layer and by creating an effective barrier between the semiconductor surface and the surrounding environment. In this study, various surface modifications on InAs are developed with the goal of decreasing the leaching of indium and arsenic. The leaching of indium and arsenic from modified substrates was assessed in physiological conditions using inductively coupled plasma mass spectrometry (ICP-MS). Substrates modified with 11-mercapto-1-undecanol (MU) and graft polymerized with poly(ethylene) glycol (PEG) were most effective at preventing indium and arsenic leaching. These surfaces were characterized using contact angle analysis, ellipsometry, atomic force microscopy (AFM), and X-ray photoelectron spectroscopy (XPS). Substrates modified with collagen and synthetic polyelectrolytes were least effective, due to the destructive nature of acidic environments on InAs. The toxicity of modified and unmodified InAs, along with raw indium, arsenic, and PEG components was assessed

  17. 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 (Phytate, organic phosphorus, degree of phosphorus saturation, soil, leachate, poultry manure

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2009-01-15

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

  19. A study on the recycling of scrap integrated circuits by leaching.

    Science.gov (United States)

    Lee, Ching-Hwa; Tang, Li-Wen; Popuri, Srinivasa R

    2011-07-01

    In order to minimize the problem of pollution and to conserve limited natural resources, a method to recover the valuable metals such as gold, silver and copper) present in the scrap integrated circuits (ICs) was developed in the present study. Roasting, grinding, screening, magnetic separation, melting and leaching were adopted to investigate the efficiency of recovery of gold, silver and copper from scrap ICs. The collected scrap IC samples were roasted at 850 °C to destroy their plastic resin sealing material, followed by screening and magnetic separation to separate the metals from the resin residue. The non-ferrous materials (0.840 mm) were mainly composed of copper and could be melted into a copper alloy. Non-ferrous materials containing gold (860.05 ppm), silver (1323.12 ppm) and copper (37259.7 ppm) (size less than 50 mesh) were recovered 100% by a leaching process and thiourea was used as a leaching reagent.

  20. Leaching behavior of butanedionedioxime as gold ligand

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

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

  1. Leaching from denture base materials in vitro

    Energy Technology Data Exchange (ETDEWEB)

    Lygre, H.; Solheim, E.; Gjerdet, N.R. [School of Medicine, Univ. of Bergen (Norway)

    1995-04-01

    Specimens made from denture base materials were leached in Ringer Solution and in ethanol. The specimens comprised a heat-cured product processed in two different ways and two cold-cured materials. The organic compounds leaching from the specimens to the solutions were separated, identified, and quantified by a combined gas-chromatography and gas-chromatography/mass-spectrometry technique. Additives and degradation products, possibly made by free radical reactions, were released from the denture base materials. In Ringer solution only phthalates could be quantified. In ethanol solvent, biphenyl, dibutyl phthalate, dicyclohexyl phthalate, phenyl benzoate, and phenyl salicylate were quantified. In addition, copper was found in the ethanol solvent from one of the denture base materials. The amount of leachable organic compounds varies among different materials. Processing temperature influences the initial amount of leachable compounds. 36 refs., 7 figs., 1 tab.

  2. Duality properties of Gorringe-Leach equations

    OpenAIRE

    Grandati, Yves; Berard, Alain; Mohrbach, Herve

    2004-01-01

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

  3. Duality properties of Gorringe-Leach equations

    CERN Document Server

    Grandati, Yves; Mohrbach, Herve

    2007-01-01

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

  4. Gold and Silver Extraction from Leach Solutions

    Directory of Open Access Journals (Sweden)

    Bagdaulet K. Kenzhaliyev

    2014-03-01

    Full Text Available There has been carried out an investigation on the extraction of gold and silver from thiosulfate solutions: standard test and technological solutions of chemical and electrochemical leaching. The influence of related metals on the process of extracting gold from solution was studied. There has been conducted a comparative study of the IR spectra of solutions after the sorption of gold, silver and related metals.

  5. 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.

  6. 从低浓度含钯硝浸液中富集钯工艺研究%Research on Concentration of Palladium from Nitric Acid Leaching Solution Containing Palladium

    Institute of Scientific and Technical Information of China (English)

    赵祝鹏; 王兴; 崔家友; 张善辉; 侯绍彬; 姜学利

    2016-01-01

    针对在银电解过程中产生的银阳极泥,研究了硝酸浸出溶解银和钯,然后采用食盐沉银、黄药富集分离钯的生产工艺。研究结果表明,银回收率在98%以上,钯富集率达到93%以上。同时,该工艺具有成本低、操作简单、贵金属回收率高等优点。%Aimed at silver anode slime produced in the course of silver electrolytic refining, Ag and Pd are dissolved by nitric acid, then Ag is subsided by salt and Pd is concentrated by butyl xanthate. The recovery rate of Ag is over 98%, the accumulation rate of Pd reaches to 93%. The process has the advantages of low cost, simple operation, high precious metals recovery.

  7. Deconstructing Multicultural Counseling Competencies Research: Comment on Owen, Leach, Wampold, and Rodolfa (2011)

    Science.gov (United States)

    Worthington, Roger L.; Dillon, Frank R.

    2011-01-01

    The present article offers a commentary and critique of the research presented by J. Owen, M. M. Leach, B. Wampold and E. Rodolfa (2011). Given the complexity of the research methodology, findings, and conclusions, the authors provide a concise summary of findings, study limitations, and conclusions followed by a detailed critique of the study.…

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2004-09-01

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

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

    Science.gov (United States)

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

    2015-10-21

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

  10. MINTEQ modeling for evaluating the leaching behavior of heavy metals in MSWI fly ash.

    Science.gov (United States)

    Zhang, Yan; Jiang, Jianguo; Chen, Maozhe

    2008-01-01

    At present, all kinds of municipal solid waste incineration (MSWI) fly ash stabilization technology has been reported and successfully applied in many countries. However, leaching procedures are very different that the technologies lack uniform standard, and it is even impossible to predict the long-term stabilization. Geochemical model can explain the environmental stabilization based on chemical phase and thermodynamic crystal structure, and it is also able to guide the development of environment-friendly stabilization technology and choosing of chemical agents. Both experiment analysis and geochemical modeling were used to study the correlation between leaching behavior of MSWI fly ash and variation of pH. Dissolution/precipitation mechanism was applied in the simulation. The result indicated that the pH-dependent leaching behavior predicted by Visual MINTEQ is well in agreement with the result of pH-dependent test. pH value of leachate can significantly change the leaching behavior of MSWI fly ash. The leaching behavior of heavy metals for Pb and Cd is controlled by dissolution/precipitation mechanism, whereas for Zn and Ni, it is effected by surface adsorption reaction over a special extent of pH value.

  11. MINTEQ modeling for evaluating the leaching behavior of heavy metals in MSWI fly ash

    Institute of Scientific and Technical Information of China (English)

    ZHANG Yan; JIANG Jianguo; CHEN Maozhe

    2008-01-01

    At present, all kinds of municipal solid waste incineration (MSWI) fly ash stabilization technology has been reported and successfully applied in many countries. However, leaching procedures are very different that the technologies lack uniform standard, and it is even impossible to predict the long-term stabilization. Geochemical model can explain the environmental stabilization based on chemical phase and thermodynamic crystal structure, and it is also able to guide the development of environment-friendly stabilization technology and choosing of chemical agents. Both experiment analysis and geochemical modeling were used to study the correlation between leaching behavior of MSWI fly ash and variation of pH. Dissolution/precipitation mechanism was applied in the simulation. The result indicated that the pH-dependent leaching behavior predicted by Visual MINTEQ is well in agreement with the result of pH-dependent test. pH value of leachate can significantly change the leaching behavior of MSWI fly ash. The leaching behavior of heavy metals for Pb and Cd is controlled by dissolution/precipitation mechanism, whereas for Zn and Ni, it is effected by surface adsorption reaction over a special extent of pH value.

  12. Valorization of GaN based metal-organic chemical vapor deposition dust a semiconductor power device industry waste through mechanochemical oxidation and leaching: A sustainable green process.

    Science.gov (United States)

    Swain, Basudev; Mishra, Chinmayee; Lee, Chan Gi; Park, Kyung-Soo; Lee, Kun-Jae

    2015-07-01

    Dust generated during metal organic vapor deposition (MOCVD) process of GaN based semiconductor power device industry contains significant amounts of gallium and indium. These semiconductor power device industry wastes contain gallium as GaN and Ga0.97N0.9O0.09 is a concern for the environment which can add value through recycling. In the present study, this waste is recycled through mechanochemical oxidation and leaching. For quantitative recovery of gallium, two different mechanochemical oxidation leaching process flow sheets are proposed. In one process, first the Ga0.97N0.9O0.09 of the MOCVD dust is leached at the optimum condition. Subsequently, the leach residue is mechanochemically treated, followed by oxidative annealing and finally re-leached. In the second process, the MOCVD waste dust is mechanochemically treated, followed by oxidative annealing and finally leached. Both of these treatment processes are competitive with each other, appropriate for gallium leaching and treatment of the waste MOCVD dust. Without mechanochemical oxidation, 40.11 and 1.86 w/w% of gallium and Indium are leached using 4M HCl, 100°C and pulp density of 100 kg/m(3,) respectively. After mechanochemical oxidation, both these processes achieved 90 w/w% of gallium and 1.86 w/w% of indium leaching at their optimum condition.

  13. Slurry filtration and cake washing after the HCl-leach of magnesite and serpentine—continuous washing model

    Science.gov (United States)

    Blackburn, Denis; Nagamori, Meguru

    1994-06-01

    Four different ores of magnesite and serpentine were leached with hydrochloric acid to produce concentrated magnesium chloride liquors. The neutralized slurries were filtered at a constant pressure, and the cakes were washed with water. As for filtration, the mass balance was calculated based on magnesium analyses, while the Darcy-Ruth equation was used to investigate the kinetics and assess the specific resistance of cakes. As for washing, the mass balance and kinetics were accounted for in terms of a continuous mathematical model, which is compatible with the Moncrieff equation. This new model explains well the washing test results. Washing operations can be optimized only in economical terms, and a complete set of mathematical formulae was presented for the optimization procedure.

  14. Irrigation management in Mediterranean salt affected agriculture: how leaching operates

    Directory of Open Access Journals (Sweden)

    Angela Libutti

    2012-03-01

    and relative drainage volumes according to a three steps procedure of covariance analysis. A simple, general and comprehensive leaching model is thus presented. Results showed that salt build up into the soil can be very rapid, generally occurring within a single irrigated summer crop cycle. Rainfalls of the autumn-winter period had a crucial role in the removal of salts brought into the soil by summer irrigation. This paper strongly emphasises that additional fresh water supply is of great importance to establish acceptable soil conditions. Two suitable periods for intentional leaching were identified.

  15. Etude de la récupération du zinc des résidus de lixiviation Recuperation study of zinc from leaching residues

    Directory of Open Access Journals (Sweden)

    Benarioua Younes

    2013-11-01

    Full Text Available La présente étude a été menée dans le but de valoriser le zinc des résidus de lixiviation. Pour ce but, nous avons retenu la méthode goethite qui présente certains avantages. La concentration d'acide sulfurique, la température et le temps de traitement ceux sont les paramètres choisis lors de ce travail. L'effet de trois paramètres sélectionnés sur la dissolution du zinc des résidus de lixiviation a été étudié. Il est démontré que la teneur en zinc augmente avec l'augmentation des valeurs paramétriques. The present work has been conducted in the objective of valorising the zinc from leaching residues. For this purpose we have retained the goethite method which presented some advantages. The sulfuric acid concentration, temperature and time of treatment are those parameters chosen for this study. The effect of three selected parameters on dissolution of zinc from leaching residues was investigated. It is shown that when values parametric increases the content of zinc increase.

  16. Leaching optimization of municipal solid waste incineration ash for resource recovery: A case study of Cu, Zn, Pb and Cd.

    Science.gov (United States)

    Tang, Jinfeng; Steenari, Britt-Marie

    2016-02-01

    Ash from municipal solid waste incineration (MSWI) may be quite cumbersome to handle. Some ash fractions contain organic pollutants, such as dioxins, as well as toxic metals. Additionally, some of the metals have a high value and are considered as critical to the industry. Recovery of copper, zinc and lead from MSWI ashes, for example, will not only provide valuable metals that would otherwise be landfilled but also give an ash residue with lower concentrations of toxic metals. In this work, fly ash and bottom ash from an MSWI facility was used for the study and optimization of metal leaching using different solutions (nitric acid, hydrochloric acid and sulfuric acid) and parameters (temperature, controlled pH value, leaching time, and liquid/solid ratio). It was found that hydrochloric acid is relatively efficient in solubilizing copper (68.2±6.3%) and zinc (80.8±5.3%) from the fly ash in less than 24h at 20°C. Efficient leaching of cadmium and lead (over 92% and 90% respectively) was also achieved. Bottom ash from the same combustion unit was also characterized and leached using acid. The metal yields were moderate and the leachates had a tendency to form a gelatinous precipitate, which indicates that the solutions were actually over-saturated with respect to some components. This gel formation will cause problems for further metal purification processes, e.g. solvent extraction.

  17. Batch leaching tests of motherboards to assess environmental contamination by bromine, platinum group elements and other selected heavy metals.

    Science.gov (United States)

    Almeida, César; Grosselli, Melina; González, Patricia; Martínez, Dante; Gil, Raúl

    2016-02-01

    In this study, a batch leaching test was executed to evaluate the toxicity associated with chemicals contained in motherboards. The leaching solutions used were distilled water, nitric acid, acetic acid and synthetic acid rain solution. A total of 21 elements including Ag, As, Au, Br, Cd, Co, Cr, Cu, Hf, Ir, Mn, Ni, Os, Pb, Pd, Pt, Rd, Rh, Se, U and Zn were analyzed. In this study, the pH values of all the leachates fell within the range of 2.33-4.88. The highest concentrations of metals were obtained from the acid rain solution, whilst the maximum value of bromine was achieved with solution of acetic acid. Appreciable concentrations of platinum group elements were detected with concentrations around 3.45, 1.43, 1.21 and 22.19 µg L(-1) for Ir, Pd, Pt and Rh, respectively. The different leaching of the motherboards revealed the predominant presence of the toxic substances in the leached from the e-waste.

  18. Leaching of chromium from chromium contaminated soil: Speciation study and geochemical modeling

    Directory of Open Access Journals (Sweden)

    Anđelković Darko H.

    2012-01-01

    Full Text Available Distribution of chromium between soil and leachate was monitored. A natural process of percolating rainwater through the soil was simulated in the laboratory conditions and studied with column leaching extraction. Migration of chromium in the soil is conditioned by the level of chromium soil contamination, the soil organic matter content, and rainwater acidity. Chromium (III and chromium(VI were determined by spectrophotometric method with diphenilcarbazide in acidic media. Comparing the results of chromium speciation in leachate obtained by experimental model systems and geochemical modelling calculations using Visual MINTEQ model, a correlation was observed regarding the influence of the tested parameters. Leachate solutions showed that the concentration of Cr depended on the organic matter content. The influence of pH and soil organic matter content is in compliance after its definition through experimental and theoretical way. The computer model - Stockholm Humic Model used to evaluate the leaching results corresponded rather well with the measured values.

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

    Directory of Open Access Journals (Sweden)

    Davide Ciceri

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

  20. 赣南某红土镍矿常压酸浸液中杂质离子的除去%Removing Impurity Ions From the Constant-pressured Acid Leaching Lixivium of a Laterite Nickel Ore in South of Ganzhou

    Institute of Scientific and Technical Information of China (English)

    周晓文; 刘智林

    2012-01-01

    The constant-pressured acid leaching lixivium of a laterite nickel in south of Ganzhou contains impurities Fe,Mg,Cu,Pb,Zn ions which are separated with the nickel ions difficulty. Used the amarillite craft to wipe off the ferric i-ons,the removal rate of ferric ions could reach 99 % ,used sodium fluoride craft to wipe off heavy metal ions,the removal rate of cupper ion,lead ion and zinc ion all could reach 90% ,used sodium fluoride craft to wipe off the magnesium ions,the removal rate of magnesium ions could reach 90% ,the loss rate of nickel ions in every craft was about 15% ,12% and 5%.%赣南某红土镍矿常压酸浸液中含有铁、镁、铜、铅、锌等杂质离子,且这些杂质离子与镍离子分离较困难.采用黄钠铁矾法去除铁离子,达到了99%的去除率;采用硫化钠沉淀法去除铜、铅、锌等重金属离子,达到了90%的去除率;采用氟化钠法去除镁离子,达到了90%的去除率;各作业段镍离子作业损失率分别为15%、12%、5%.