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Sample records for acid leaching present

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

    The acid mine drainage is one of the most important environmental problems associated with mining of ores containing sulfides. The treatment of these acid effluents, which contains high concentrations of dissolved metals and anions, is generally by liming. The wastes generated in the liming process may present significant toxicity and their storage in inappropriate places waiting for treatment is a common issue that requires solution. Osamu Utsumi Mine located in the city of Caldas, Minas Gerais, has been facing this problem. The residue of this mine consists of an alkaline sludge generated from the neutralization of the pH of acid mine drainage and is rich in various metals, including uranium. The main concern is the long term stability of this residue, which is in permanent contact with the acid water in the open pit. The recovery of uranium by hydrometallurgical techniques, such as acid leaching, can be a viable alternative on the reuse of this material. This study aimed at establishing a specific leaching process for the recovery of uranium present in the sludge from Caldas uranium mine. Some parameters such as solid/liquid ratio (0.09 to 0.17), time of leaching (1 to 24 hours) and concentration of sulfuric acid (pH from 0 to 3.0) were assessed. The results showed that it is possible to extract 100% of uranium present in the sludge. The concentration of U3O8 in the residue was 0.25%, similar to the content of the vein ores which is around 0.20% to 1.0%. The best experimental leaching condition is solid/liquid ratio of 0.17, pH 1.0 and 2 hours of reaction at room temperature (25 deg C). The content of uranium in the liquor is around 440 mgL-1. The recovery of the uranium from the liquor is under investigation by ionic exchange. (author)

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

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

    2011-07-01

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

  3. Reductive Acid Leaching of Low Grade Manganese Ores

    Alok Prasad Das; Sarpras Swain; Shriyanka Panda; Nilotpala Pradhan; Lala Behari Sukla

    2012-01-01

    Manganese recoveries from low-grade ores using organic acids as reducing agents were investigated in the present work. The acid leaching potential of both oxalic acid and citric acid were estimated. Manganese leaching amount were measured by using standard manganese curve and estimated by titration method. Effects of various acid concentrations on leaching efficiency were studied. The observed result suggested prominent manganese recovery of 66% by oxalic acid at 2 M concentration whereas cit...

  4. A review of CANMET's acid chloride leaching of uranium ores

    Conventional sulphuric acid leach processing of uranium ore is technically and economically viable but presents some environmental concerns because almost all of the radium and the sulphides, especially pyrite (an acid generating mineral), present in the ore report to the tailing disposal sites. In order to obtain leach tailings with a radium (226) content of 20-25 pCi/g solids and essentially free of pyrite, an alternative HCl leach process has been developed. Hydrochloric acid leaching of low-grade pyritic uranium ore (e.g. Elliot Lake U-ore) followed by flotation for pyrite removal from the final leach residue yielded tailings essentially free of pyrite and radionuclides, the radium level in the tailings being in the range of 25-30 pCi g-1 solids. Acid chloride leaching of Midwest Lake uranium ore, under various conditions (e.g., HCl, HCl-CaCl2-O2 pressure, HCL-FeCl3) provided high extraction of U, Ni, As and Ra and tailings with radium levels above 177 pCi g-1 solids. However HCl leaching of the radium preleached Midwest Lake uranium ore provided the best extraction of U(>99%), Ni(88%), As(90%) and Ra (98%) and the tailings with only 108 pCi g-1 solids radium. Of course, out of these 108 pCi/g solids, at least 66 pCi/g solids were tied up with the residual uranium (0.02%) in the tailings, and the remaining radium (42 pCi/g solids) present as sparingly soluble radium salt/salts (e.g., RaS04). The acid chloride leaching process for uranium ore has definite technological and environmental merits but presently compares unfavourably both in capital and operating costs with the conventional sulphuric acid leach process. However, the economics of the HCl leach process could become viable when the costs of removing the radium (226) and the sulphides (i.e., the acid generating minerals) from sulphuric acid leach tailings are taken into consideration

  5. Leaching of Electronic Waste Using Biometabolised Acids

    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.

  6. Application of agglomerated acid heap leaching of clay-bearing uranium ore in China

    The permeability of ore mass has a great influence on the leaching period of heap leaching and the leaching efficiency, hence the uranium ores with high content of clay present a significant difficulty to acidic heap leaching. The Research Institute of Uranium Mining has engaged over years of studies on the cementing agents of acidic agglomeration, agglomeration method, as well as the curing measures of pelletted balls. On the basis of these studies, several types of clay-bearing ores have been tested with good results. The technique of agglomerated acid heap leaching has been successfully applied in a uranium mine. Since agglomeration has effectively increased the permeability of ore mass, its leaching period is decreased from 200 days to 60 days, the leaching efficiency from less than 40% up to 96%, comparing with direct heap leaching programme. (author)

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

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

    2015-12-01

    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.

  8. Study of lanthanide leaching from phosphosemihydrate by nitric acid

    Nitric acid leaching of lanthanides from phosphosemihydrate (PSH) prepared by treating the Khibiny apatite concentrate at nitric acid concentration of 2-8% and S:L ratio 1:3 was studied under laboratory conditions. Results of experiments are compared with the data obtained during sulfuric acid leaching. It is shown that during one-stage process nitric acid leaches lanthanides from PSH more effectively that sulfuric acid. However, in case of multiple use of the same solution for successive leaching of several portion of PSH, accumulation of lanthanides in nitric acid solutions occurs less intensively than in sulfuric acid ones

  9. Leaching of Some Lanthanides from Phosphogypsum Fertilizers by Mineral Acids

    The phosphate rock contains trace amounts of uranium and lanthanides. When treating this rock with H2SO4 produces phosphoric acid together with 5 times of its quantity of phosphogypsum (PG) precipitate as a by-product. The lanthanides in the rock are mostly present in the PG. After a slight modification of the precipitated PG, some portion of the PG is used as a low grade phosphate fertilizer (PGF) containing ∼ 2% P2O5. Leaching of different lanthanides from PGF by the mineral acids solutions namely; HCl, H2SO4 and HNO3 is investigated in relation the acid concentration, the mixing time, and acid volume to mass of PGF ratio (L/S) as well as temperature. It is found that the highest leaching efficiency was obtained using 3 .0 M HNO3 , L / S = 3.0 and mixing time of 3.0 hr , at room temperature. The total lanthanides content in the PGF, was found to be about 480 mg/kg. After three cycle of leaching, the leached out lanthanides from PGF was more than 66 %

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

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

  11. Column leaching of chromium and nickel from a contaminated soil using EDTA and citric acid

    This study investigates the column leaching of a soil contaminated mainly with Cr and Ni by using two chelants: citric acid (biodegradable) and EDTA (non-biodegradable) followed with water rinse. The chelants lead to Cr and Ni leaching, in addition to major elements (Ca, Fe, Mg, Al, Mn and Zn) showing the dissolution of soil mineral constituents. EDTA leaches more major elements and Ni than citric acid related to the respective stability of metal–chelant complexes; citric acid leaches more Cr than EDTA, certainly because of a substitution reaction with Cr(VI). In the case of alternating chelant/water applications, leaching occurs during the chelant applications, but also during water applications. In the case of chelant/water applications followed by continuous water application, both Cr and Ni leach over time. This increased mobility could be due to the residual chelant present in soil as well as to the dissolution/mobilization of mineral or organic soil fractions. - Highlights: ► Column leaching of an industrial soil contaminated with chromium and nickel. ► Citric acid or EDTA were used alternatively or followed with water rinse. ► Chelants lead to Cr and Ni leaching and the dissolution of soil mineral constituents. ► Leaching of these two metals proceeds continuously during water rinse. ► Chelants deeply impacted Cr and Ni mobility. - Citric acid or EDTA application deeply impact Cr and Ni mobility during column leaching of a contaminated soil.

  12. Leaching behavior of uranium and vanadium using strong sulfuric acid from Korean black shale ore

    The present scientific study focused on leaching behavior of uranium and vanadium from Korean domestic ore. The leaching process experimental conditions optimized for uranium and vanadium metals recovery from Korean domestic ore and developed the basic experimental procedures such as time, particle size, acid influence, temperature effect and pulp density (PD) behavior. Acid influence on leaching process was tested and noted that 2.0 M sulfuric acid concentration is the optimized conditions for present study. The time influence on leaching process was observed and its optimized 2 h for complete leaching process. The temperature influence tested and optimized the 80 deg C for complete leaching process and PD is 50 % (wt%). The bench scale experiments developed in a laboratory and tested in pilot level each batch 100 kg of ore sample. (author)

  13. In situ leaching of uranium

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

  14. Manual of acid in situ leach uranium mining technology

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

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

    A. Strzałkowska; M. Wojtala; J. Siwka

    2012-01-01

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

  16. Mechanochemical leaching of chalcopyrite concentrate by sulfuric acid

    Sina Hejazi; Jalil Vahdati khaki; Abolfazl Babakhani

    2016-01-01

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

  17. Mechanochemical leaching of chalcopyrite concentrate by sulfuric acid

    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.

  18. Leaching of vanadium from sulphuric acid manufacture spent catalysts

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

    2001-01-01

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

  19. Canopy leaching of subtropical mixed forests under acid rain

    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+.

  20. Sulfuric acid leaching of mechanically activated manganese carbonate ore

    Kenan Yıldız

    2010-01-01

    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 accele...

  1. Sulfuric acid leaching of mechanically activated manganese carbonate ore

    Yıldız, Kenan

    2000-01-01

    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 acce...

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

    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.

  3. Experimental study on bio-leaching of high sulphuric acid consumption uranium ore by adding sulphide

    In order to decrease acid consumption and increase leaching rate, an experiment on bio-leach-ing of low grade uranium ore by adding sulphide was done. Compared with conventional leaching method, the leaching rate of uranium is improved by 3% and the leaching period was reduced to 60 days from 90 days by bio-leaching method of adding sulphide. In order to decrease acid consumption with bio-leaching by adding sulphide obviously, robust bacteria to sulphide should be chosen. (authors)

  4. Sulfuric acid leaching of mechanically activated manganese carbonate ore

    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.

  5. Leaching of sodium carbonate cakes by nitric acid

    The interaction has been studied of soda cakes of fluorite-rare-earth concentrate with nitric acid. The effect of a number of factors on extraction of REE into a nitric solution has been considered: the final acidity of the pulp, the duration of leaching, and the ratio between solid and liquid phases. The effect of adding aluminium nitrate into the pulp has also been studied. It has been shown that three-stage counterflow leaching of soda cakes with nitric acid increases REE extraction approximately by 10%

  6. Case history of a pilot-scale acidic in situ uranium leaching experiment. Report of investigations/1982

    The Bureau of Mines assisted the Rocky Mountain Energy Co. in a pilot-scale in situ leaching experiment at Casper, Wyo., to determine if sulfuric acid can be used as a cost-effective alternative lixiviant (leachant) for uranium in situ leaching. This experiment, which lasted more than 2 years, is the first fully documented pilot-scale operation in which the leaching-restoration cycle was completed using sulfuric acid instead of the more common carbonate-bicarbonate leachant. This report describes activities at the experimental site, presents extensive geochemical data from startup to site restoration, compares laboratory and field experiments, and discusses the environmental aspects of acid leaching

  7. Groundwater leaching of neutralized and untreated acid-leached uranium-mill tailings

    Tailings neutralization was examined to determine the effect of neutralization on contaminant release. Column leaching of acid extracted uranium mill tailings from Exxon Highland Mill, Wyoming, Pathfinder Gas Hills Mill, Wyoming, and the Dawn Midnite Mill, Washington, resulted in the flushing of high concentrations of salts in the first four pore volumes of leachate, followed by a steady decrease to the original groundwater salt concentrations. Neutralization decreased the concentration of salts and radionuclides leaching from the tailings and decreased the volume of solution required to return the solution to the groundwater pH and EC. Radium-226 and uranium-238 leached quickly from the tailings in the initial pore volumes of both neutralized and unneutralized tailings, and then decreased significantly. 6 figures, 5 tables

  8. STUDY ON HIGH ACID LEACHING REACTIVE CALCINED KAOLIN

    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.

  9. Leaching of vanadium from sulphuric acid manufacture spent catalysts

    Recovery of vanadium contained in spent catalyst 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 diffusion controlled. the work is completed by developing an industrial leaching cycle simulation with the aim of reproducing real performance of spent, proposing operating conditions, and verifying the non-toxic character of the final residue obtained. (Author) 18 refs

  10. Sulfuric acid leaching kinetics of South African chromite

    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.

  11. Leaching of vanadium from sulphuric acid manufacture spent catalysts

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

    Brunelli, K.; Dabalà, M.

    2015-04-01

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

  13. Thermal behaviour of ground and unground acid leached vermiculite

    Pérez-Maqueda, L. A.; Maqueda, C.; Pérez-Rodríguez, J. L.; Šubrt, Jan; Černý, Zbyněk; Balek, V.

    2012-01-01

    Roč. 107, č. 2 (2012), s. 431-438. ISSN 1388-6150 R&D Projects: GA MŠk LC523 Institutional research plan: CEZ:AV0Z40320502 Keywords : vermiculite * grinding * acid leaching * DTA * TG * EGA * emanation thermal analysis Subject RIV: CA - Inorganic Chemistry Impact factor: 1.982, year: 2012

  14. Nitric acid leaching of polymetallic middlings of concentration

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

    2013-01-01

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

  15. [Leaching kinetics of josephinite tailings with sulfuric acid].

    Chen, An-An; Zhou, Shao-Qi; Huang, Peng-Fei

    2013-07-01

    Leaching is the most important step of josephinite tailing recycle technology. This step can separate the valuable metal Mg from Si and other impure metal. Effects of sulfuric acid on leaching Mg efficiency from josephinite tailings were investigated. To obtain the leaching behavior, a modified unreacted shrinking core model that based on the experimental data was used to determine the dissolution kinetic parameters. The model was significant and showed that the dissolution of Mg2+ in josephinite tailing was controlled by the produce layer diffusion, apparent activation reaction energy E = 34.04 kJ x mol(-1). The produce layers obstruct the forward reaction of the dissolution of Mg2+. PMID:24028005

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

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

    2005-01-01

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

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

    A. Strzałkowska

    2012-12-01

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

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

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

  19. Fractionation of iron isotopes during leaching of natural particles by acidic and circumneutral leaches and development of an optimal leach for marine particulate iron isotopes

    Revels, Brandi N.; Zhang, Ruifeng; Adkins, Jess F.; John, Seth G.

    2015-10-01

    Iron (Fe) is an essential nutrient for life on land and in the oceans. Iron stable isotope ratios (δ56Fe) can be used to study the biogeochemical cycling of Fe between particulate and dissolved phases in terrestrial and marine environments. We have investigated the dissolution of Fe from natural particles both to understand the mechanisms of Fe dissolution, and to choose a leach appropriate for extracting labile Fe phases of marine particles. With a goal of finding leaches which would be appropriate for studying dissolved-particle interactions in an oxic water column, three particle types were chosen including oxic seafloor sediments (MESS-3), terrestrial dust (Arizona Test Dust - A2 Fine), and ocean sediment trap material from the Cariaco basin. Four leaches were tested, including three acidic leaches similar to leaches previously applied to marine particles and sediments (25% acetic acid, 0.01 N HCl, and 0.5 N HCl) and a pH 8 oxalate-EDTA leach meant to mimic the dissolution of particles by organic complexation, as occurs in natural seawater. Each leach was applied for three different times (10 min, 2 h, 24 h) at three different temperatures (25 °C, 60 °C, 90 °C). MESS-3 was also leached under various redox conditions (0.02 M hydroxylamine hydrochloride or 0.02 M hydrogen peroxide). For all three sample types tested, we find a consistent relationship between the amount of Fe leached and leachate δ56Fe for all of the acidic leaches, and a different relationship between the amount of Fe leached and leachate δ56Fe for the oxalate-EDTA leach, suggesting that Fe was released through proton-promoted dissolution for all acidic leaches and by ligand-promoted dissolution for the oxalate-EDTA leach. Fe isotope fractionations of up to 2‰ were observed during acidic leaching of MESS-3 and Cariaco sediment trap material, but not for Arizona Test Dust, suggesting that sample composition influences fractionation, perhaps because Fe isotopes are greatly fractionated

  20. Uranium leaching using mixed organic acids produced by Aspergillus niger

    Both of culture temperature and pH value had impacts on the degree of uranium extraction through changing types and concentrations of mixed organic acids produced by Aspergillus niger, and significant interactions existed between them though pH value played a leading role. And with the change of pH value of mixed organic acids, the types and contents of mixed organic acids changed and impacted on the degree of uranium extraction, especially oxalic acid, citric acid and malic acid. The mean degree of uranium extraction rose to peak when the culture temperature was 25 deg C (76.14 %) and pH value of mixed organic acids was 2.3 (82.40 %) respectively. And the highest one was 83.09 %. The optimal culture temperature (25 deg C) of A. niger for uranium leaching was different from the most appropriate growing temperature (37 deg C). (author)

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

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

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

    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.

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

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

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

    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.

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

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

    2013-01-01

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

  6. Recovery of vanadium (V) from spent catalysts used in sulfuric acid production units by acid or alkaline leaching

    The present paper, studies the recovery of vanadium from the spent catalyst by using acidic or alkaline leaching technique. The optimal conditions of spent catalyst leaching have been studied. It has been shown that 20%(w/w) of sulfuric acid is the most suitable for leaching process at 70 Centigrade. The precipitation of vanadium using some alkaline media (Na2CO3, (NH4)CO3 and NH4OH) has been also studied, it has been shown that ammonium hydroxide was the best at 60 degree, and iron was co-precipitated with vanadium which pollute the obtained red cake. So it is necessary to use liquid-liquid extraction technique for the separation between vanadium and iron and to have iron free red cake. (author)

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

    M. TCHOUMOU; M. ROYNETTE

    2007-01-01

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

  8. Metal release from fly ash upon leaching with sulfuric acid or acid mine drainage

    Generation of electricity by coal-fired power plants produces large quantities of bottom ash and fly ash. New power plants commonly use fluidized bed combustion (FBC) boilers, which create ashes with high neutralization potential (NP). These ashes, due to their alkaline nature, are often used in surface mine reclamation to neutralize acidity and reduce hydraulic conductivity of disturbed overburdens. Conventional fly ashes from older power plants exhibit a range of pH and NP, with some ashes having neutral or acidic pH and low NP values, and may not be good candidates for supplying alkalinity in reclamation projects. In this study, the authors used two acidic solutions to leach a low NP fly ash (LNP ash) and two FBC ashes (FBC1 and FBC2). After passing 78 pore volumes of sulfuric acid and 129 pore volumes of acid mine drainage (AMD) through these ash materials several trace elements were found at high levels in the leachates. LNP fly ash leachates had high arsenic and selenium concentrations with sulfuric acid leaching, but showed low arsenic and selenium concentrations after leaching with AMD. Leaching with AMD caused the iron and aluminum inherent in AMD to complex these elements and make them unavailable for leaching. Lead, cadmium, and barium concentrations in fly ash leachates were not high enough to cause water pollution problems with either leaching solution. For both leaching solutions, manganese was released from LNP ash at a constant level, FBC1 ash did not release manganese, and FBC2 ash released manganese only after the NP had been exhausted by >60 pore volumes of leaching

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

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

  10. Concentration-Purification of Uranium from an Acid Leaching Solution

    Guettaf, H.; Becis, A.; Ferhat, K.; Hanou, K.; Bouchiha, D.; Yakoubi, K.; Ferrad, F.

    2009-11-01

    Chemical processes for the elaboration of uranium concentrate from uranium ore have been studied. This process is composed of successive units operations: crushing, milling, acid conventional leaching, filtration-washing, purification-concentration by ion exchange resins and uranium precipitation. The acid leaching operating conditions allow us to obtain a recovery uranium rate of 93%. The uranium concentration of the pregnant solution is approximately of 1.2 g/l. This value justifies the use of ion exchange resins to the concentration-purification of our pregnant solution. We have noticed that the pregnant solution contains a relatively high phosphate concentration which causes a premature uranium precipitation at pH=1.8. This pH value is in general, considered optimal to obtain the highest amount of fixed uranium by the anionic resin. To avoid the precipitation of uranium, the pH=1.5 has been fixed. We have obtained at this condition a good adsorption capacity. A 75% uranium concentrate have been elaborated, but the filtration of this concentrate has been very difficult. We have also noticed an excessive sulphate concentration. In order to improve this process, we have tested nitrates as eluant at different operating conditions.

  11. Nickel recovery from spent Raneynickel catalyst through dilute sulfuric acid leaching and soda ash precipitation.

    Lee, Jin Young; Rao, S Venkateswara; Kumar, B Nagaphani; Kang, Dong Jun; Reddy, B Ramachandra

    2010-04-15

    Pharmaceutical industry makes extensive use of Raneynickel catalyst for various organic drug intermediates/end products. Spent catalysts contain environmentally critical and economically valuable metals. In the present study, a simple hydrometallurgical process using dilute sulfuric acid leaching was described for the recovery of nickel from spent Raneynickel catalyst. Recovery of nickel varied with acid concentration and time, whereas temperature had negligible effect. Increase of S/L ratio to 30% (w/v) showed marginal effect on nickel (90%) recovery, whereas Al recovery decreased drastically to approximately 20%. Under the optimum conditions of leaching viz: 12 vol.% H(2)SO(4), 30 degrees C, 20% solid to liquid (S/L) ratio and 120 min reaction time, it was possible to recover 98.6% Ni along with 39.2% Al. Leach liquor [pH 0.7] containing 85.0 g/L Ni and 3.25 g/L Al was adjusted to pH 5.4 with 30 wt.% alkali for quantitative aluminum removal. Nickel loss was about 2% during this Al removal step. Nickel from the purified leach liquor was recovered as nickel carbonate by adding required amount of Na(2)CO(3). The purity of NiCO(3) product was found to be 100% with a Ni content of 48.6%. Na(2)SO(4) was recovered as a by-product with a purity of 99%. Complete process is presented. PMID:20018448

  12. Humification degree of Rendzina soil humic acids influenced by carbonate leaching and land use

    Radmanović Svjetlana B.; Đorđević Aleksandar R.; Nikolić Nataša S.

    2015-01-01

    The humification degrees of humic acids extracted from calcareous and decarbonated Rendzinas under different land use were characterized upon their optical properties, to evaluate the influence of carbonate leaching (decarbonation) and different land uses. Decarbonation influenced the humification degree of humic acids positively. Base leaching and acidification of decarbonated Rendzinas led to a decrease in humification degree of humic acids. In calcareous...

  13. Leaching mechanism of boric acid and cobalt from the paraffin waste form

    Leach test with upper sections of the cylindrical paraffin waste forms was conducted to determine the leaching mechanism of boric acid and Cobalt. Using two specimens with different diameters, leaching rates of boric acid and Cobalt were measured in accordance with ANSI/ANS-16.1 standard leach test procedure for 30 days. After the leach test, the weight of the dried specimen was measured to confirm the leaching rates. The experiment result showed that the boric acid and Cobalt were congruently released by the diffusion-controlled dissolution, but Cobalt released a little bit more rapidly than the boric acid. One-dimensional shrinking core model based on the diffusion-controlled dissolution was derived to simulate the experiment result. The shrinking core model and experiment results showed a good agreement, and the model estimated the receding front of the boric acid accurately. Also, the earlier appearance of Cobalt can be explained with the shrinking core model

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

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

  15. Leaching of vanadium from stone coal with sulfuric acid

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

    2009-01-01

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

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

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

    2016-05-01

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

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

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

    2015-02-01

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

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

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

    2012-01-01

    Interest for application of hydrometallurgical processes in a processing of complex sulphide ores and concentrates has increased in recent years. Their application provides better metal recoveries and reduced emission of gaseous and toxic ageneses in the environment. The kinetics and mechanism of sphalerite leaching from complex sulphide concentrate with sulphuric acid and sodium nitrate solution at standard conditions was presented in this paper. The influences of temperature and time ...

  19. Effects of simple acid leaching of crushed and powdered geological materials on high-precision Pb isotope analyses

    Todd, Erin; Stracke, Andreas; Scherer, Erik E.

    2015-07-01

    We present new results of simple acid leaching experiments on the Pb isotope composition of USGS standard reference material powders and on ocean island basalt whole rock splits and powders. Rock samples were leached with cold 6 N HCl in an ultrasonic bath, then on a hot plate, and washed with ultrapure H2O before sample digestion in HF-HNO3 and chromatographic purification of Pb. Lead isotope analyses were measured by Tl-doped MC-ICPMS. Intrasession and intersession analytical reproducibilities of repeated analyses of both synthetic Pb solutions and Pb from single digests of chemically processed natural samples were generally better than 100 ppm (2 SD). The comparison of leached and unleached samples shows that leaching consistently removes variable amounts of contaminants that differ in Pb isotopic composition for different starting materials. For repeated digests of a single sample, analyses of leached samples reproduce better than those of unleached ones, confirming that leaching effectively removes most of the heterogeneously distributed extraneous Pb. Nevertheless, the external reproducibility of leached samples is still up to an order of magnitude worse than that of Pb solution standards (˜100 ppm). More complex leaching methods employed by earlier studies yield Pb isotope ratios within error of those produced by our method and at similar levels of reproducibility, demonstrating that our simple leaching method is as effective as more complex leaching techniques. Therefore, any Pb isotope heterogeneity among multiple leached digests of samples in excess of the external reproducibility is attributed to inherent isotopic heterogeneity of the sample. The external precision of ˜100 ppm (2 SD) achieved for Pb isotope ratio determination by Tl-doped MC-ICPMS is thus sufficient for most rocks. The full advantage of the most precise Pb isotope analytical methods is only realized in cases where the natural isotopic heterogeneity among samples in a studied suite is

  20. Acid-leached α-MnO2 nanowires for electrochemical energy storage

    Byles, Bryan; Subramanian, Arunkumar; Pomerantseva, Ekaterina

    2014-09-01

    We present synthesis, acid-leaching, characterization and electrochemistry of α-MnO2 nanowires with tunnel crystal structure. This material is used as a matrix for lithium ions intercalation to provide insights into the effects of postsynthesis treatment on charge storage properties. Hydrothermal treatment of precursors produced 20 - 200 nm thick and tens of microns long nanowires. Acid leaching was carried out in the concentrated nitric acid at room temperature and resulted in the change of material composition and surface area. Original α-MnO2 nanowires showed initial discharge specific capacity of 96 mAh/g, while acid-leached material exhibited higher capacity values. This work forms the basis for future study aimed at understanding of correlation between crystal structure, composition and morphology of the "host" matrix and nature of the "guest" ions for beyond lithium electrochemical energy storage. In addition, we demonstrate single nanowire electrochemical cells for the study of electrochemically-correlated mechanical properties of the nanowires.

  1. Flotation-nitric acid leach procedure for increasing uranium recovery from a refractory ore

    The Bureau of Mines investigated a flotation-nitric acid leach procedure as part of the goal to maximize minerals and metals recovered from primary and secondary domestic resources. Studies were conducted on an ore that contained carbon-bearing and sulfide mineralization that rendered a portion of the ore refractory (resistant) to conventional leaching technology. The procedure investigated for treating the ore consisted of the following: (1) separation by flotation of the carbonaceous and sulfidic components from the ore, (2) leaching the flotation concentrate with nitric acid at 1000 to 1100C, (3) leaching the flotation tailings with sulfuric acid, and (4) processing the combined leached slurries in a conventional manner to recover yellow cake. In step 2, HNO3 is converted to gaseous products from which it is regenerated by reacting these products with air and water for further leaching. An overall uranium extraction of 96% was achieved by this procedure

  2. Leaching of initial and burnt danburite by sulfuric acid

    Sulfuric acid decomposition of initial and burnt danburite was studied in this work. The interaction between initial and pre baked danburite by sulfuric acid was studied as well. The influence of temperature, process duration and concentration of sulfuric acid on the rate of component extraction from initial and burnt danburite was defined. The chemical composition of initial danburite is presented.

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

    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.

  4. Kinetics of Hydrochloric Acid Leaching of Titanium from Titanium-Bearing Electric Furnace Slag

    Zheng, Fuqiang; Chen, Feng; Guo, Yufeng; Jiang, Tao; Travyanov, Andrew Yakovlevich; Qiu, Guanzhou

    2016-05-01

    The hydrochloric acid leaching of titanium from titanium-bearing electric furnace slag was investigated under different experimental conditions. The results indicate that particle size, hydrochloric acid concentration and reaction temperature were of significance to the leaching kinetics. Specifically, reaction temperature was the most important factor followed by hydrochloric acid concentration and particle size. The shrinking core model was used to describe the leaching process which was controlled by surface chemical reaction. The kinetic equation was obtained and the activation energy was found to be 43.16 kJ/mol. Iron and calcium species were almost completely dissolved in the acid when the extraction degree of titanium reached 99.84%. MgO (19.34 wt.%) and Al2O3 (32.45 wt.%) in the spinel were still in the leaching residue and SiO2 (43.53 wt.%) in the form of quartz remained in the leaching residue.

  5. Copper solvent extraction from chalcopyrite concentrate acid leach solutions by LIX 984

    Elamari K.

    2006-01-01

    Full Text Available Copper production from ores or sulphide concentrates is classically realized by pyrometallurgical route. In this study, hydrometallurgical treatment of a copper sulphide concentrate, provided by Hajar Mine (ONA-Group, Morocco, was tested by using a mixture of nitric and hexafluorosilicic acids. Copper is present in the solid product as chalcopyrite and its amount is 28.1 % by weight. Leaching stage allows to dissolve more than 90% of copper witch is accompanied, in the same averages, by Zn and Fe. The leach solution obtained has pH = 0.6 and Eh = 580 mV/ENH and contains 19.3 g/L Cu, 18.1 g/L Fe, 4.5 g/L Zn and 0.03 g/L Pb. The recovery of copper from this leach solution was curried out by solvent extraction using Lix 984, diluted in Escaid 110. McCabe - Thiele distribution isotherms showed that at pH 1.7 total and selective copper extraction can be realized with Øo:Øa =1.5:1 in 3 extraction stages. Stripping of the loaded copper by treating the organic phases was easily obtained by a sulphuric acid solution.

  6. Acid chloride leaching of Midwest Lake uranium ore (northern Saskatchewan, Canada)

    The feasibility of acid chloride leaching (i.e. alternative leaching process) of high-grade complex uranium ore was studied on Midwest Lake uranium ore, one of the main objectives of the work being to produce effluents and tailings almost free from radioisotopes and other toxic materials. Irrespective of leachants, uranium extractions were always high (∼99%). 32 refs.; 5 tabs

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

    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.

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

    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.

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

    Orac D.; Havlik T.; Maul A.; Berwanger M.

    2015-01-01

    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 sec...

  10. Removal of radium-226 from radium-contaminated soil using humic acid by column leaching method

    In this study, evaluation of radium-226 removal from radium-contaminated soil using humic acid extracted from peat soil by column leaching method was carried out. Humic acid of concentration 100 ppm and pH 7 was leached through a column packed with radium-contaminated soil and leachates collected were analysed with gamma spectrometer to determine the leached radium-226. Results obtained indicated low removal of radium-226 between 1 - 4 %. Meanwhile, leaching profile revealed that radium-226 was bound to soil components with three different strength, thus resulting in three phases of radium-226 removal. It was estimated that the total removal of radium-226 from 10 g radium-contaminated soil sample studied could be achieved using approximately 31500 - 31850 ml HA solutions with leaching rate of 1 ml/ min. (author)

  11. Solvent extraction of uranium from lean grade acidic sulfate leach liquor with alamine 336 reagent

    This paper describes the solvent extraction studies carried out on an acidic low assay uranium bearing leach liquor generated during sulfuric acid leaching of a refractory uranium ore using alamine 336-isodecenol-kerosene reagent combine. The leach liquor has a U3O8 content of about 270 mg/L, free acidity 2.4 N H2SO4 and total dissolved solids concentration of 260 g/L. Process parameteric variation studies indicated strong influence of free acidity of the leach liquor, alamine 336 concentration and aqueous to organic phase ratio on the extraction efficiency of uranium. An extraction efficiency of about 95% was achieved when the free acidity of leach liquor was 1 N H2SO4 or lower, using 2% (v/v) alamine 336 at ambient temperature with an aqueous to organic phase ratio of 1:1. The loading capacity under these conditions was 1.2 g/L of U3O8. About 98% of the uranium values could be stripped from the loaded organic using 1 N NaCl in 0.2 N H2SO4. The solvent extraction studies aided in developing a suitable process flowsheet for treating refractory uranium ores which need high acidity during leaching and relatively lower acidity for purification by solvent extraction. (author)

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

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

  13. Application of acid pugging and ferric salts leaching on West Central Sinai uraniferrous siltstone

    Application of acid pugging as well as leaching with ferric salts [FeC13 and Fe2(SO4)3] methods were investigated to overcome the solid - liquid separation problem normally faced in the conventional acid leaching methods. The applied methods minimized the leachant consumption and leaching time. In addition, the radium removal during the ferric salts leaching was actually taken in consideration to meet the environmental requirements. The acid pug leaching experiments were conducted by using 10 gm concentrated H2SO4 (equal to 200 kg/ton in the conventional leaching methods) upon 50 gm sample fractions. The pug was cured at 110oC for 1.5 hours. After curing, agitation leaching was performed with distilled water using a solid - liquid ratio of 1/3 for 6 hours at room temperature. The obtained leaching efficiencies were 95.7% for U, 97.3% for Cu and almost complete leaching for Mn. This method could also be applied at the mine sites on ores when making use of the sunlight for only a few hours a day. Bench scale studies proved that when applying the curing step in the sunlight for 4 hours using the other optimum operating conditions, U dissolution efficiency reached about 85.6% and about 86.6% for Cu but it was only about 25.7% for Mn. In comparison, application of ferric salts leaching on the ore proved that 93.3% and 37% U dissolutions were obtained when using 100 kg/t Fe2(SO4)3 versus FeC13, respectively. With respect to both Cu and Mn leaching efficiencies, it was found that higher recoveries were obtained when using FeC13 than when using Fe2(SO4)3. Tests were performed to improve the poor uranium leaching efficiencies in the FeC13 leaching method by the addition of HC1 which acted as initiating reagent. The results indicated that by adding 40 kg/t FeC13 an improvement of the uranium leaching was obtained, 92.2%. (author)

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

    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. PMID:24007993

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

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

    2014-01-01

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

  16. Mini-pilot-scale hydrochloric acid leaching of an Elliot Lake uranium ore

    An hydrochloric acid leaching process has been found to provide high uranium recoveries and low residual radium content in the tailings. Several uranium extraction process flowsheets have been developed based on hydrochloric acid leaching of uranium ores, of pyrite-free tails from pyrite flotation minerals and of magnetic concentrates from high intensity magnetic separation of radioactive minerals. Two-stage hydrochloric acid leaching of an Elliot Lake uranium ore with 4-hr. retention in each stage provided 98% overall recovery of uranium and tailings containing 30 pCi g-1 Ra. However, the economics of the acid chloride process compares unfavourably both in capital and in operating costs with the conventional sulphuric acid process, unless such a process provides significant savings in environmental costs. (orig.)

  17. Effect of nitric acid leaching on the separation of U and common impurities from solid (U, Pu, Ag) analytical waste

    The effect of leaching a solid analytical waste of (U,Pu)O2 and AgCl with concentrated nitric acid for different time intervals was studied. The amount of Pu/U leached was found to be nearly same in the selected time interval 15-90 minutes. Hence the effect of multi-step leaching on the dissolution of U/Pu was studied. After four steps of 15 minute leaching, entire uranium was leached along with about 3% Pu. Later keeping the time constant, the effect of nitric acid molarity on the leaching of U and Pu was investigated. The leaching of impurities was found to decrease with each step. However the amounts of rare earths and Ag leached were found to be negligible. (author)

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

    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.

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

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

    2015-09-01

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

  20. Effect of acid leaching on upgrading the graphite concentrate from West Kalimantan (Indonesia)

    Syarifuddin, Fahmi; Florena, Fenfen Fenda; Hanam, Eko Sulistio; Trisko, Nici; Kustiyanto, Eko; Enilisiana, Rianto, Anton; Arinton, Ghenadi

    2016-02-01

    In this research an attempt has been done for upgrading the carbon content on processed graphite concentrate obtained from Sanggau Regency, West Kalimantan, Indonesia by acid leaching. The purpose of this research was to find optimal conditions for increasing graphite purity by eliminating the impurities, in particular, sillica - which is easy to remove by hydrofluoric acid. The concentrate contained 69.74% FC ranging from 149 µm to 841 µm. The optimal leaching parameters were time reaction 120 minutes, temperature 180° C, solid-liquid ratio 1:5 and purity of acid 48%. The determination of the carbon content showed that the carbon grade was 98% FC.

  1. Extraction of uranium from anomaly ores no 1,6,8 in salt domes of Bandar Abbas region using column leaching by seawater in sulfuric acid medium

    Column leaching is one of the experimental methods which is used for identifying the specifications of uranium ores. From the efficiency point of view, the process has some complications and usually it is applied in parallel with the conventional leaching process in order to facilitate of finding an appropriate design and operational method, to be applicable in an large practical scale. In this research work, at the first stage, the existed free chlorine in the samples was washed out using seawater. Then, in a process of acid leaching with seawater and sulfuric acid by the use of the column leaching was applied. The results show that the maximum of 85% of uranium from the ore of Anomali ≠1 is extracted. The extra residual of the used acid dose not react with the uranium and therefore it will increase the free acidity of the leach liquor. In Anomali ≠6, the extraction efficiency of uranium is 75%, while in Anomali ≠8, using 30 periods of leaching, the efficiency is 81%. However, the maximum efficiency achievement has to be avoided by the non-economical circumstances. Based on some comparisons, it is shown that the presence of chlorine in ore will affect the efficiency. The capability of seawaterin uranium extraction from salted, compared with the normal or sweat waterhas some advantages. These include: reduction of the operational period, less acid consumption, and reduction in the ore leaching costs. Thus, the heap leaching industry is believed to be a valuable and economical method for uranium extraction, where the needs of utilizing the complicated technical facilities can be reduced. The present work is the first research project on the uranium extraction and concentration in solution containing chlorine. Our experimental results can provide a valuable pattern for the heap leaching of uranium ores design from arches shaped in the region Bandar Abbas

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

    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.

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

    Rao, G. V.; Prakash, S.

    1998-01-01

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

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

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

    2016-07-15

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

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

    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.

  6. Hydrochloric acid leaching of uranium, thorium, radium and rare-earth elements, from an Elliot lake radioactive ore

    Extraction of uranium by commercial methods using sulphuric acid developed a lot of environmental problems. To avoid such problems, other uranium extraction techniques have been adopted including fluorination, chlorination, chlorine assisted leaching, hydrochloric acid leaching, etc. This work is oriented towards the study of the factors controlling the hydrochloric acid leaching. The target of the study is to extract the total amount of U, Th, Ra-226 and rare earth elements. By using a suitable combination of the leaching factors, it was possible to achieve the designed target

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

    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.

  8. Comparison of acid leaching and fusion techniques to determine uranium in soil samples by alpha spectrometry.

    Dirican, Abdullah; Şahin, Mihriban

    2016-03-01

    Dissolution of radionuclides of interest is an indispensable first step in the alpha spectrometric analysis of soil samples. In this study a uranium recovery method for the analysis of uranium isotopes in soil samples is presented. Two different soil sample dissolution techniques were used: digestion in open beaker and fusion. The results of these techniques were compared. Two proficiency test samples and one reference material prepared by the IAEA were analyzed. Better results were obtained by fusion dissolution technique but impurities were higher than with acid leaching. Results of two techniques were more or less similar within the uncertainty limits. The detection limit (a(#)) was evaluated as part of the quality control. PMID:26651172

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

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

    2016-11-01

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

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

    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

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

    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.

  12. Sulfuric acid baking and leaching of spent Co-Mo/Al2O3 catalyst.

    Kim, Hong-In; Park, Kyung-Ho; Mishra, Devabrata

    2009-07-30

    Dissolution of metals from a pre-oxidized refinery plant spent Co-Mo/Al(2)O(3) catalyst have been tried through low temperature (200-450 degrees C) sulfuric acid baking followed by mild leaching process. Direct sulfuric acid leaching of the same sample, resulted poor Al and Mo recoveries, whereas leaching after sulfuric acid baking significantly improved the recoveries of above two metals. The pre-oxidized spent catalyst, obtained from a Korean refinery plant found to contain 40% Al, 9.92% Mo, 2.28% Co, 2.5% C and trace amount of other elements such as Fe, Ni, S and P. XRD results indicated the host matrix to be poorly crystalline gamma- Al(2)O(3). The effect of various baking parameters such as catalyst-to-acid ratio, baking temperature and baking time on percentage dissolutions of metals has been studied. It was observed that, metals dissolution increases with increase in the baking temperature up to 300 degrees C, then decreases with further increase in the baking temperature. Under optimum baking condition more than 90% Co and Mo, and 93% Al could be dissolved from the spent catalyst with the following leaching condition: H(2)SO(4)=2% (v/v), temperature=95 degrees C, time=60 min and Pulp density=5%. PMID:19121897

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

    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....

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

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

    2003-01-01

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

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

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

    2016-03-01

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

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

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

  17. Study of the Dissolution Behavior of Muscovite in Stone Coal by Oxygen Pressure Acid Leaching

    Xue, Nan-nan; Zhang, Yi-min; Liu, Tao; Huang, Jing

    2016-02-01

    The dissolution behavior of muscovite in stone coal during the oxygen pressure acid leaching process was studied. The study showed that the dissolution behaviors of V, Al, and K were similar. K was the most easily leached, followed by Al, and then by V during oxygen pressure acid leaching process. When the reaction temperature exceeded 423 K (150 °C), alunite was generated, which led to vanadium losses because of its absorption performance. The dissolution of the muscovite in stone coal mainly depended on H2SO4 concentration and temperature. O2 had a main effect not on muscovite's dissolution but on the V3+ oxidation. During the oxygen pressure acid leaching process, (1) the interfacial K in the muscovite lattice was dissolved rapidly, producing a new interface; (2) for charge balance, the interfacial O absorbed hydrogen ions to form hydroxy; (3) the interfacial hydroxy reacted with hydrogen ions and left vacancy as a result of O loss, producing more new surface to expose more Al, V, and Si; (4) the interfacial Al or V was exchanged by hydrogen ions and V3+ was oxidized to V4+ and V5+; and (5) Si hardly reacted with H+ and generated high-Si surface.

  18. Influence of microwaves on the leaching kinetics of uraninite from a low grade ore in dilute sulfuric acid.

    Madakkaruppan, V; Pius, Anitha; T, Sreenivas; Giri, Nitai; Sarbajna, Chanchal

    2016-08-01

    This paper describes a study on microwave assisted leaching of uranium from a low-grade ore of Indian origin. The host rock for uranium mineralization is chlorite-biotite-muscovite-quartzo-feldspathic schist. The dominant presence of siliceous minerals determined leaching of uranium values in sulfuric acid medium under oxidizing conditions. Process parametric studies like the effect of sulfuric acid concentration (0.12-0.50M), redox potential (400-500mV), particle size (600-300μm) and temperature (35°-95°C) indicated that microwave assisted leaching is more efficient in terms of overall uranium dissolution, kinetics and provide relatively less impurities (Si, Al, Mg and Fe) in the leach liquor compared to conventional conductive leaching. The kinetics of leaching followed shrinking core model with product layer diffusion as controlling mechanism. PMID:27045621

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

    2012-01-01

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

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

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

    2014-04-01

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

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

    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.

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

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

    2014-02-01

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

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

    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.

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

    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.

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

    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.

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

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

    2015-04-01

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

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

    金程; 赵颖华; 李登新

    2011-01-01

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

  8. Brazilian quartz purification by leaching technique

    High purity quartz powder presents an increasing demand for the production of silica glass, widely used for semiconductor processing, particularly for photo-voltaic solar cells manufacturing. Motivated by the huge natural quartz potential of this country, the present paper studied the cleansing effect of acid leaching on Brazilian quartz powder, investigating the following parameters: type of solvent, temperature and leaching time. Still, aqueous leaching tests with ultrasound activation were also performed in order to verify its efficiency. The ideal conditions found for leaching,with a 74,2% purification degree, were achieved using a mixture of hydrofluoric acid with hydrochloric acid at 100 deg C for 6 hours. A leaching procedure longer than 6 hours is not necessary, since Fe, Ca, K and Mg amounts do not show significant variation after such time. Also, aqueous leaching caused purification rates higher than 30% for most of the impurities tested, proving itself as a effective leaching method (author)

  9. Synergistic extraction of uranium from acidic sulfate leach liquor using D2EHPA mixed with TOPO

    Uranium extraction from sulfate leach liquor acid by D2EHPA and TOPO mixture in kerosene was investigated. The effect of different factors affecting the extraction mechanism such as sulfate leach liquor acid, D2EHPA and TOPO concentrations and temperature have been studied. The mathematical treatment for the obtained date suggested that the composition of synergistic extraction species is (UO2(D)2T). The logarithm of the apparent equilibrium constant, log Kex, of synergistic extraction reaction has been evaluated, to be 3.35 ± 0.1. The effect of temperature on extraction process was investigated and the apparent values of the thermodynamics parameters (∆H, ∆G and ∆S) were 38.2 kJ/mol, -19.1 kJ/mol and 192.5 J/mol respectively. (author)

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

    Aichun Zhao

    2016-01-01

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

  11. Study on underground-water restoration of acid in-situ leaching process with electrodialytic desalination

    The study focus undergrounder water restoration of acid in-situ leaching process with electrodialysis desalination in Yining Uranium Mine. It is shown in field test that electrodialysis desalination is an effective method for underground water restoration of acid in-situ leaching process. When TDS of underground-water at the decommissioning scope is 10-12 g/L, and TDS will be less than 1 g/L after the desalination process, the desalination rate is more than 90%, freshwater recovery 60%-70%, power consumption for freshwater recovery 5 kW·h/m3, the distance of the desalination flow 12-13 m, current efficiency 80%, and the throughput of the twin membrane 0.22-0.24 m3/(m2·d)

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

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

    2010-07-01

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

  13. Sulfuric Acid and Ammonium Sulfate Leaching of Alumina from Lampang Clay

    Numluk, Paweena; Chaisena, Aphiruk

    2012-01-01

    The rapid development of the global alumina industry has led to a considerable increase in the production alumina and processing of alumina from non-bauxitic sources. Lampang clays comprise various minerals that contain about 22.70 wt% of extractable alumina. Local clay was ground, activated by calcination and treated with sulfuric acid to extract alumina. In the activation step, the effects of temperature and time on the extraction of alumina and iron were investigated. The leaching experime...

  14. Evaluation of NaOH leaching techniques to extract humic acids from palaeosols

    It can be shown quite conclusively that the often used technique (AAA) of leaching palaeosol samples with hot or boiling dilute HCl solution, followed by treatment with up to 2% NaOH solution and a further treatment with dilute HCl solution may not remove all of the so-called humic acids from palaeosol samples. In fact, in many cases it does not remove any of the humic acids, only carbohydrates, amino acids and other organic compounds. This can be shown by examination of the visible spectrum (400-700 nm) of the 'humic acid' extract in alkaline solution. Hence, many of the reported 14C results from the 'humin' fraction of palaeosols are actually from the humic acid fraction which is tightly bound to the clay component of the palaeosol. The NaOH leach also has the potential to introduce carboxylic acid groups from atmospheric CO2 into phenol groups. A reevaluation of humic acid extracts of palaeosols collected from the Loess Plateau in China has been made, with analyses comparing the properties of the various organic extracts. Also, an extraction technique based on recommendations from the International Humic Substances Society, incorporating removal of impurities by chromatography plus a decarboxylation step is proposed

  15. The acid pressure leaching process for the Key Lake Project, Canada

    Key Lake ore contains 2.5% U3O8, 2.5% Ni and 1.5% As. A new leaching process will be applied to yield a saleable product and to establish environmentally acceptable mining and milling operations. The process involves pressurized acid leaching, CCD, solvent extraction, bulk precipitation of nickel and arsenic, yellowcake precipitation, radium removal, ammonium sulphate crystallization and subaerial tailings deposition secured against seepage by an under-drainage system. The first process idea was developed in the laboratories of the Uranerz GmbH at Bonn, in 1976. The Key Lake process was optimized at the pilot plant of Sherritt-Gordon, Canada, between 1977 and the end of 1979. Engineering was carried out in 1981 by Wright Engineers. Construction of the facilities started in late 1981 and will be completed in 1983. The core of the Key Lake mill is the two-stage leaching section comprising four storage pachucas followed by four primary leach pachucas, 10 secondary vertical autoclaves and a neutralization section for the bulk precipitation of arsenic and nickel with subsequent radium removal. The solvent extraction plant with four mixer-settlers for extraction, four for scrubbing, four for stripping and two for regeneration is of Krebs design. The Key Lake operation will produce 12x106 1b/a U3O8. (author)

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

    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.

  17. Humification degree of Rendzina soil humic acids influenced by carbonate leaching and land use

    Radmanović Svjetlana B.

    2015-01-01

    Full Text Available The humification degrees of humic acids extracted from calcareous and decarbonated Rendzinas under different land use were characterized upon their optical properties, to evaluate the influence of carbonate leaching (decarbonation and different land uses. Decarbonation influenced the humification degree of humic acids positively. Base leaching and acidification of decarbonated Rendzinas led to a decrease in humification degree of humic acids. In calcareous Rendzinas, the humification degree of humic acids was in descending order: grassland>arable land>forest land, and in decarbonated Rendzinas: arable land>grassland>forest land. The humification degree of humic acids was higher in the calcareous forest and grassland Rendzinas compared to decarbonated Rendzinas, analogously in decarbonated arable land compared to calcareous arable land Rendzinas. Differences in the humification degree of humic acids among various land uses that emerged between calcareous and decarbonated Rendzinas indicate the dominant influence of soil chemical characteristics (carbonate content and pH value compared with the quantity and quality of the organic litter input.

  18. Antimony leaching in plastics from waste electrical and electronic equipment (WEEE) with various acids and gamma irradiation

    Highlights: • We have proposed a method to recover antimony from electronic plastics. • The most efficient acid solution was sodium hydrogen tartrate in dimethyl sulfoxide. • Gamma irradiation did not influence the antimony leaching ability. - Abstract: There has been a recent interest in antimony since the availability in readily mined areas is decreasing compared to the amounts used. It is important in many applications such as flame retardants and in the production of polyester, which can trigger an investigation of the leachability of antimony from plastics using different acids. In this paper, different types of acids are tested for their ability to leach antimony from a discarded computer housing, made of poly(acrylonitrile butadiene styrene), which is a common plastic type used in electrical and electronic equipment. The acid solutions included sodium hydrogen tartrate (0.5 M) dissolved in either dimethyl sulfoxide or water (at ca. 23 °C and heated to ca. 105 °C). The metal content after leaching was determined by inductively coupled plasma optical emission spectroscopy. The most efficient leaching medium was the heated solution of sodium hydrogen tartrate in dimethyl sulfoxide, which leached almost half of the antimony from the poly(acrylonitrile butadiene styrene). Gamma irradiation, which is proposed to improve the mechanical properties in plastics, was used here to investigate the influence of antimony leaching ability. No significant change in the amount of leached antimony could be observed

  19. Separation of Fe (III) ions from acidic leach liquor of metasummatite Saghand ore by anion exchange resins

    Ferric ions in dilute acidic leach liquor of uranium ore of Saghand were separated by anion exchange resins. In this research, a simulated solution similar to the actual leach liquor of Saghand was prepared. The simulated solution which was containing chloride and ferric ions. rare earth elements, and some other impurities was treated by different types of Dowex anion exchange resins for ferric ions removal. It appeared that hydrochloric acidic concentration, resin types and particle sizes have a great impact on ferric ions adsorption. Dowex 1 X 4 (200-400 mesh) has the best adsorption of 91% in simulated solution and 79% in actual leach liquor of uranium ore of Saghand respectively

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

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

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

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

  2. Cadmium, lead and zinc leaching from smelter fly ash in simple organic acids-Simulators of rhizospheric soil solutions

    Emissions from base-metal smelters are responsible for high contamination of the surrounding soils. Fly ash from a secondary Pb smelter was submitted to a batch leaching procedure (0.5-168 h) in 500 μM solutions of acetic, citric, or oxalic acids to simulate the release of toxic metals (Cd, Pb, Zn) in rhizosphere-like environments. Organic acids increased dissolution of fly ash by a factor of 1.3. Cadmium and Pb formed mobile chloro- and sulphate-complexes, whereas Zn partly present in a citrate (Zn-citrate-) complex is expected to be less mobile due to sorption onto the positively charged surfaces of hydrous ferric oxides (HFO) and organic matter (OM) in acidic soil.

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

    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. Acid Leaching of SHS Produced MgO/TiB2

    Lok, Jonathan Y.

    2006-01-01

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

  5. Recovery of H2SO4 from an acid leach solution by diffusion dialysis

    Diffusion dialysis with a series of anion exchange membranes was used to recover H2SO4 from an acid leach solution produced during the vanadium manufacturing process. The effects of sulfuric acid, FeSO4 and VOSO4 concentration, flow rate and flow rate ratio on the recovery of H2SO4 were investigated. The results showed that sulfuric acid permeated well through the membranes used, while metal ions were efficiently rejected. The recovery of H2SO4 increased as the sulfate concentration of the feed increased and the flow rate ratio of water to feed increased. More than 80% of the H2SO4 could be recovered from the leach solution which contained 61.7 g/L free H2SO4, 11.2 g/L Fe and 4.60 g/L V at a flow rate of 0.19 x 10-3 m3/h m2. V and Fe ion rejection were within 93-95 and 92-94%, respectively. A preliminary economic evaluation revealed that an investment in this process could be recovered within 27 months.

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

    蔡创开; 庄荣传; 林鸿汉

    2015-01-01

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

  7. Influence of phase composition on sulfuric acid leaching of tantalum-containing alloys

    Influence of chemical and phase composition of tantalum-niobium iron-base alloys (2-5% Ta, 3-6% Nb, up to 12% Si, 1.4-2.4% C) on kinetics of their leaching by aqueous solutions of sulfuric acid and by mixture of sulfuric and hydrofluoric acids in the temperature range from 60 to 100 deg C was studied using the methods of elementary and X-ray phase analyses. It is shown that the use of the above-mentioned mixture of acids permits transferring to solution of up to 94% iron, 90% manganese, 70% silicon and preparing a solid product, which is 3-5 times more concentrated in terms of tantalum and niobium, depending on initial content of silicon in the alloys

  8. Uranium adsorption from the sulphuric acid leach liquor containing more chlorides with cation-exchange resin SL-406

    The feasibility of uranium adsorption was studied from the sulphuric acid leach liquor of a uranium ore containing more chlorides with cation-exchange resin SL-406. The influence of some factors on uranium adsorption was investigated. It was shown that the resin possesses better selectivity, stability and higher capacity. It can be effectively used to recovery uranium from leach liquors of uranium ores containing more chlorides

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

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

    2016-03-01

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

  10. Determination of humic acid in alkali leaching solution of uranium by spectophotrometry-COD method

    It is one of the main causes of extraction emulsification or resin toxicosis during alkali leaching process in uranium metallurgy which organic matters including humic acid exist in lixiviums. In order to study the effect of humic acid in uranium metallurgy, a method for determination of content of humic acid in aqueous solution need to be established. Spectrophotometry is a simple and convenient method in humic acid analysis. However, accuracy of spectrophotometry can be reduced greatly because of interference of uranium and other elements in the humic acid solutions. Although chemical oxygen demand (COD) method is a common analysis way of organic matters in aqueous solutions, the concentration of humic acid cannot be directly measured. In this paper, COD method is related with spectrophotometry to avoid the interference of uranium and ensure the accurate analysis of humic acid. The results showed that the detection limit of the method was 1.78 mg/L and the recovery rate was 101.2%. (authors)

  11. Extraction of methylmercury from tissue and plant samples by acid leaching

    Hintelmann, Holger; Nguyen, Hong T. [Trent University, Chemistry Department, Peterborough, ON (Canada)

    2005-01-01

    A simple and efficient extraction method based on acidic leaching has been developed for measurement of methylmercury (MeHg) in benthic organisms and plant material. Methylmercury was measured by speciated isotope-dilution mass spectrometry (SIDMS), using gas chromatography interfaced with inductively coupled plasma mass spectrometry (GC-ICP-MS). Reagent concentration and digestion temperature were optimized for several alkaline and acidic extractants. Recovery was evaluated by addition of MeHg enriched with CH{sub 3}{sup 201}Hg{sup +}. Certified reference materials (CRM) were used to evaluate the efficiency of the procedure. The final digestion method used 5 mL of 4 mol L{sup -1} HNO{sub 3} at 55 C to leach MeHg from tissue and plant material. The digest was further processed by aqueous phase ethylation, without interference with the ethylation step, resulting in 96{+-}7% recovery of CH{sub 3}{sup 201}Hg{sup +} from oyster tissue and 93{+-}7% from pine needles. Methylmercury was stable in this solution for at least 1 week and measured concentrations of MeHg in CRM were statistically not different from certified values. The method was applied to real samples of benthic invertebrates and inter-laboratory comparisons were conducted using lyophilized zooplankton, chironomidae, and notonectidae samples. (orig.)

  12. Extraction of methylmercury from tissue and plant samples by acid leaching.

    Hintelmann, Holger; Nguyen, Hong T

    2005-01-01

    A simple and efficient extraction method based on acidic leaching has been developed for measurement of methylmercury (MeHg) in benthic organisms and plant material. Methylmercury was measured by speciated isotope-dilution mass spectrometry (SIDMS), using gas chromatography interfaced with inductively coupled plasma mass spectrometry (GC-ICP-MS). Reagent concentration and digestion temperature were optimized for several alkaline and acidic extractants. Recovery was evaluated by addition of MeHg enriched with CH3 201Hg+. Certified reference materials (CRM) were used to evaluate the efficiency of the procedure. The final digestion method used 5 mL of 4 mol L(-1) HNO3 at 55 degrees C to leach MeHg from tissue and plant material. The digest was further processed by aqueous phase ethylation, without interference with the ethylation step, resulting in 96 +/- 7% recovery of CH3 201Hg+ from oyster tissue and 93+/-7% from pine needles. Methylmercury was stable in this solution for at least 1 week and measured concentrations of MeHg in CRM were statistically not different from certified values. The method was applied to real samples of benthic invertebrates and inter-laboratory comparisons were conducted using lyophilized zooplankton, chironomidae, and notonectidae samples. PMID:15662514

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

    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. PMID:25619126

  14. Radionuclide Leaching from Residual Solids Remaining after Acid Dissolution of Composite K East Canister Sludge

    Laboratory tests were performed to examine mixed nitric/hydrofluoric acid leach treatments for decontaminating dissolver residual solids (KECDVSR24H-2) produced during a 20- to 24-hr dissolution of a composite K East (KE) Basin canister sludge in 95 C 6 M nitric acid (HNO3). The scope of this testing has been described in Section 4.5 of ''Testing Strategy to Support the Development of K Basin Sludge Treatment Process'' (Flament 1998). Radionuclides sorbed or associated with the residual solids generated in the K Basin sludge treatment process can restrict disposal of this solid to the Environmental Restoration Disposal Facility (ERDF). The starting dissolver residual solid for this testing, KECDVSR24H-2, contains radionuclides at concentrations which exceed the ERDF Waste Acceptance Criteria for TRU by about a factor of 70, for 239Pu by a factor of 200, and for 241Am by a factor of 50. The solids also exceed the ERDF criterion for 137Cs by a factor of 2 and uranium by a factor of 5. Therefore, the radionuclides of greatest interest in this leaching study are first 239Pu and 241Am (both components of TRU) and then uranium and 137Cs

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

    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.

  16. Interaction of sulphuric acid solutions with carbonates and feldspar during underground uranium leaching

    The interaction of sulphuric acid solutions with calcite, dolomite and alkali feldspar at room temperature is experimentally studied. The mineral ground up to 0.63-1 mm has been mixed with crushed quartz glass and poured over by sulphate solution. The time required for sulphate solution neutralization by these minerals is determined. The interaction of sulphuric acid with calcite occurs very quickly, the solution has a neutral reaction in some days, the process with dolomite proceeds at first quickly up to total neutralization, then its rate sharply drops, the H2SO4 interaction with alkali feldspars proceeds very slowly. To estimate the extent of equilibrium between the solution and carbonates the experimental data are compared with the results of computer calculations of partial equilibria at various degrees of main reaction course. The results can be used in supplement to the processes occurring at underground uranium leaching as well as processes in oxidation and cementation zones of sulphide deposits

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

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

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

    Shun-an Zheng

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

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

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

    2012-01-01

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

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

    Nadeem Raza

    2013-01-01

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

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

    马喜红; 覃文庆; 吴雪兰; 任浏祎

    2012-01-01

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

  2. Adsorption from n-heptane/benzene liquid mixture on acid leached bentonite powders

    In this study, adsorption excess isotherms of n-heptane/benzene liquid mixture on hydrochloric acid leached bentonite powders were determined. Adsorptions were conducted at 25 °C for 48 h. Experimental results were evaluated with both Schay–Nagy (SN) and Everett (E) methods. Specific surface areas (SSN and SE) of the powders were calculated regarding monolayer adsorption capacity of the preferentially adsorbed benzene. Adsorption equilibrium constants (K ≫ 1) were obtained by the E-method. The SE and SSN values are closed to each other. SE-values were found much lower than the corresponding Brunauer, Emmett and Teller (BET)-values. This difference was discussed with respect to the interaction of adsorbed molecules with solid surface, their collision diameter, molar cross sectional surface area and orientation in dense monolayer. Even the maximum for the SE was not associated with the maxima for K and nanopore volume (V), their values changed approximately parallel to each other with respect to the HCl% by the leaching.

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

    Huang, Jinxiu; Chen, Mengjun; Chen, Haiyan; Chen, Shu; Sun, Quan

    2014-02-01

    In this work, a Brønsted acidic ionic liquid, 1-butyl-3-methyl-imidazolium hydrogen sulfate ([bmim]HSO4), was used to leach copper from waste printed circuit boards (WPCBs, mounted with electronic components) for the first time, and the leaching behavior of copper was discussed in detail. The results showed that after the pre-treatment, the metal distributions were different with the particle size: Cu, Zn and Al increased with the increasing particle size; while Ni, Sn and Pb were in the contrary. And the particle size has significant influence on copper leaching rate. Copper leaching rate was higher than 99%, almost 100%, when 1g 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 2h. Copper leaching by [bmim]HSO4 can be modeled with the shrinking core model, controlled by diffusion through a solid product layer, and the kinetic apparent activation energy has been calculated to be 25.36 kJ/mol. PMID:24246577

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

    Highlights: • A new leaching process based on Cu2+/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 Cu2+ 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 Cu2+ 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, [Cu2+] = 0.3 M)

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

    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)

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

    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

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

    Highlights: • Selective precipitation and solvent extraction were adopted. • Nickel, cobalt and lithium were selectively precipitated. • Co-D2EHPA was employed as high-efficiency extraction reagent for manganese. • High recovery percentages could be achieved for all metal values. - Abstract: Environmentally hazardous substances contained in spent Li-ion batteries, such as heavy metals and nocuous organics, will pose a threat to the environment and human health. On the other hand, the sustainable recycling of spent lithium-ion batteries may bring about environmental and economic benefits. In this study, a hydrometallurgical process was adopted for the comprehensive recovery of nickel, manganese, cobalt and lithium from sulfuric acid leaching liquor from waste cathode materials of spent lithium-ion batteries. First, nickel ions were selectively precipitated and recovered using dimethylglyoxime reagent. Recycled dimethylglyoxime could be re-used as precipitant for nickel and revealed similar precipitation performance compared with fresh dimethylglyoxime. Then the separation of manganese and cobalt was conducted by solvent extraction method using cobalt loaded D2EHPA. And McCabe–Thiele isotherm was employed for the prediction of the degree of separation and the number of extraction stages needed at specific experimental conditions. Finally, cobalt and lithium were sequentially precipitated and recovered as 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

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

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

    2015-04-15

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

  9. Recovery of metals from Cuban nickel tailings by leaching with organic acids followed by precipitation and magnetic separation

    The percolation leaching of the Cuban nickel tailings containing 0.34% Ni, 0.08% Co and 44.2% Fe was investigated by using tartaric and oxalic acids at different concentrations. About 70% Ni, 80% Co and 30% Fe were extracted after 5 days of leaching with the mixture of 0.15 mol/L tartaric acid and 0.05 mol/L oxalic acid at ambient temperature and normal pressure. Nickel and cobalt extraction of 80% as well as iron extraction of 50% were achieved from the pregnant solution by means of precipitation at 80 deg. C for 2 h. The precipitation at ambient temperature led to a similar result after 16 days. Cobalt, nickel and iron oxalates were found in the precipitate by using the X-ray diffraction method. The regeneration of acids during the precipitation step made possible the reuse of the raffinate at the leaching step. Heating of the precipitate at 200 deg. C increased the metal concentration to 1.22% Ni and 0.33% Co, which can be fed in the existing nickel plant in Moa, Cuba. The magnetic processing of the leaching residues led to a non-magnetic product containing less than 20% Fe and a magnetic product containing more than 50% Fe

  10. Specific features of sulfuric acid leaching-out of lanthanides from phosphosemihydrate

    Effect of increase in the temperature of synthesis of hydrated lanthanide orthophosphates in the range of 75-95 deg C on the degree of their chemical activity and, accordingly, on specific features of their leaching with sulfuric acid was studied. It has been ascertained that during thermal treatment of humid lanthanide orthophosphates LnPO4·(1-1.5)H2O (Ln = La, Ce or Nd) in the presence of 70 wt. % H3PO4 (their formation conditions in the course of semihydrate decomposition of apatite concentrate) increase in thermal treatment temperature from 75 to 95 deg C decreases their solubility in sulfuric acid solution by a factor of 3-4, in all probability due to reduction of their hydration degree. Therefore, insignificant increase in the temperature of semihydrate process of phosphoric acid decomposition of the Khibiny apatite can result in a noticeable decrease in chemical activity of hydrated lanthanides orthophosphates. The restoration mechanism of the lanthanide compounds chemical activity was considered

  11. Acid extractable” metal concentrations in solid matrices: a comparison and evaluation of operationally defined extraction procedures and leaching tests

    Cappuyns, Valérie; Swennen, Rudy

    2007-01-01

    In the present study, different leaching tests were applied on well- characterised samples in order to obtain information on the potential mobility of heavy metals and arsenic. The information deduced from the different methods was compared and evaluated. Besides the comparison of heavy metal release in cascade-, column- and pHstat leaching tests, attention was also paid to the assessment of release kinetics during leaching tests and to the mathematical modelling of leaching behaviour. The ai...

  12. The precipitation of radioactive radium-226 from acidic chloride leach liquors with barium chloride

    The conventional barium chloride (BaClsub(2)) precipitation has been effective in the 99+ percent removal of radium-226 as radium-barium sulphate [RaBa(SOsub(4))sub(2)] sludge, from HCl liquors produced by laboratory and pilot leaches of Canadian uranium ores. Radium-226, due to its low-level radiation characteristics, is removed as it has been identified as an environmental and long-term health problem. The formation of the RaBa(SOsub(4))sub(2) sludge was aided due to adequate sulphate (SOsub(4)) concentrations in the HCl pilot liquors produced. Recyclable Rasup(226) concentrations of about 66 pCi/L, in treated effluents, will cost about 1/10 that of effluents below federal environmental guidelines of 10 pCi Rasup(226)/L. Toxic barium (Ba) will potentially build up in effluents as recyclable Rasup(226) concentrations around 66 pCi/L. Barium, in addition to being added to liquors as BaClsub(2) precipitant, is present in the radioactive ore and HCl leach liquors

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

    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.

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

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

    2016-01-01

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

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

    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.

  16. Leaching Kinetics of Praseodymium in Sulfuric Acid of Rare Earth Elements (REE) Slag Concentrated by Pyrometallurgy from Magnetite Ore

    Kim, Chul-Joo; Yoon, Ho-Sung; Chung, Kyung Woo; Lee, Jin-Young; Kim, Sung-Don; Shin, Shun Myung [Korea Institute of Geoscience and Mineral Resources, Daejeon (Korea, Republic of); Kim, Hyung-Seop; Cho, Jong-Tae; Kim, Ji-Hye; Lee, Eun-Ji; Lee, Se-Il; Yoo, Seung-Joon [Seonam University, Asan (Korea, Republic of)

    2015-02-15

    A leaching kinetics was conducted for the purpose of recovery of praseodymium in sulfuric acid (H{sub 2}SO{sub 4}) from REE slag concentrated by the smelting reduction process in an arc furnace as a reactant. The concentration of H{sub 2}SO{sub 4} was fixed at an excess ratio under the condition of slurry density of 1.500 g slag/L, 0.3 mol H{sub 2}SO{sub 4}, and the effect of temperatures was investigated under the condition of 30 to 80 .deg. C. As a result, praseodymium oxide (Pr{sub 6}O{sub 1}1) existing in the slag was completely converted into praseodymium sulfate (Pr{sub 2}(SO{sub 4}){sub 3}·8H{sub 2}O) after the leaching of 5 h. On the basis of the shrinking core model with a shape of sphere, the first leaching reaction was determined by chemical reaction mechanism. Generally, the solubility of pure REEs decreases with the increase of leaching temperatures in sulfuric acid, but REE slag was oppositely increased with increasing temperatures. It occurs because the ash layer included in the slag is affected as a resistance against the leaching. By using the Arrhenius expression, the apparent activation energy of the first chemical reaction was determined to be 9.195 kJmol{sup -1}. In the second stage, the leaching rate is determined by the ash layer diffusion mechanism. The apparent activation energy of the second ash layer diffusion was determined to be 19.106 kJmol{sup -1}. These relative low activation energy values were obtained by the existence of unreacted ash layer in the REE slag.

  17. Leaching Kinetics of Praseodymium in Sulfuric Acid of Rare Earth Elements (REE) Slag Concentrated by Pyrometallurgy from Magnetite Ore

    A leaching kinetics was conducted for the purpose of recovery of praseodymium in sulfuric acid (H2SO4) from REE slag concentrated by the smelting reduction process in an arc furnace as a reactant. The concentration of H2SO4 was fixed at an excess ratio under the condition of slurry density of 1.500 g slag/L, 0.3 mol H2SO4, and the effect of temperatures was investigated under the condition of 30 to 80 .deg. C. As a result, praseodymium oxide (Pr6O11) existing in the slag was completely converted into praseodymium sulfate (Pr2(SO4)3·8H2O) after the leaching of 5 h. On the basis of the shrinking core model with a shape of sphere, the first leaching reaction was determined by chemical reaction mechanism. Generally, the solubility of pure REEs decreases with the increase of leaching temperatures in sulfuric acid, but REE slag was oppositely increased with increasing temperatures. It occurs because the ash layer included in the slag is affected as a resistance against the leaching. By using the Arrhenius expression, the apparent activation energy of the first chemical reaction was determined to be 9.195 kJmol-1. In the second stage, the leaching rate is determined by the ash layer diffusion mechanism. The apparent activation energy of the second ash layer diffusion was determined to be 19.106 kJmol-1. These relative low activation energy values were obtained by the existence of unreacted ash layer in the REE slag

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

    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.

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

    蒋朝金; 黄海飞; 杨跃新

    2015-01-01

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

  20. Recovery of alumina from khushab bauxite by leaching with sulphuric acid and removal of iron impurity by ethanol

    Bauxite is heterogeneous material principally composed of aluminum oxide minerals and found in all continents. It is being used in chemical, cement, refractory, abrasive, fertilizer, steel and other industries. In order to extract the alumina, the calcined samples of bauxite of Khushab area were ground to -710 meum. Sulphuric acid of purity 40% was used as leaching agent and slurry of pulp density 14% was prepared by dissolving 60 ml acid in 20 gm sample. The leaching was carried out at 90 degree C for 2 hours. The iron impurity was removed by ethanol of purity 68%. The drying, dehydration and desulphurization temperatures were kept 105 degree C, 450 degree C and 850 degree C respectively in all the stages of the process. Alumina recoveries from four samples of Sultan Mehdhi, Chamil More, Niaz Mine and Nadi locations were 20.8%, 9.81%, 15.47% and 7.78% respectively. Iron was almost completely removed as the analysis shows that the Fe/sub 2/O/sub 3/ removal was from 97.8% to 99.6%. It is concluded that leaching efficiency was quite encouraging except Nadi ore sample. However the iron free alumina recoveries were low as the analysis of Fe/sub 2/O/sub 3/ processed residue shows that it contains 72.72% to 92.94% of leached alumina in all the four experiments. (author)

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

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

    2010-01-01

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

  2. Study on uranium loss during 'Iron-Gypsum Cake' precipitation from acid leach liquor of Jaduguda ore using factorially designed experiments

    Acid leaching process for uranium recovery from ore often generates considerable amounts of impurities into the solution. It is a challenge to separate the non-valuable impurities as manageable and stable waste products for final disposal, without losing the valuable constituents. The main impurities that come with the leach liquor are iron and sulfate. Their removal is essential for meeting the iron requirement in leaching circuit and also for making the effluent suitable for recycle. Factorial design analysis was applied to study of process variables for precipitation of iron and sulphate from leach liquor with composition using CaO as precipitation reagent

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

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

    2006-11-15

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

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

    刘付朋; 刘志宏; 李玉虎; 刘智勇; 李启厚

    2014-01-01

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

  5. Present status of Kr fixation research with zeolites and evaluation method of Kr sealing and leach behavior

    For the management of 85Kr from fuel reprocessing, the combination of the liquefaction-evaporation process for its recovery and the high-pressure cylinder method for its containment is presently practical. The disposal of 85Kr by means of the cylinder alone presents a problem in the case of sea dumping due to the possible leakage. In this connection, there is the need to suppress krypton diffusion by sealing it in zeolite to improve the safety of the means. As for the 85Kr sealing in zeolite, the utilization of sodalite by Benedict et al. of Exxon and of molecular sieve 5A by Penzhorn et al. of Karlsruhe are comparatively reviewed. On the evaluation method of the Kr sealing in zeolite and leach behavior, the aspects of equilibrium adsorption quantity and the diffusion mechanism in crystals are first discussed. The results are then compared with the experimental results using molecular sieve 3A. (J.P.N.)

  6. Solution Leaching

    Chun, Tiejun; Zhu, Deqing; Pan, Jian; He, Zhen

    2014-06-01

    Recovery of alumina from magnetic separation tailings of red mud has been investigated by Na2CO3 solution leaching. X-ray diffraction (XRD) results show that most of the alumina is present as 12CaO·7Al2O3 and CaO·Al2O3 in the magnetic separation tailings. The shrinking core model was employed to describe the leaching kinetics. The results show that the calculated activation energy of 8.31 kJ/mol is characteristic for an internal diffusion-controlled process. The kinetic equation can be used to describe the leaching process. The effects of Na2CO3 concentration, liquid-to-solid ratio, and particle size on recovery of Al2O3 were examined.

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

    Morcali, Mehmet Hakan

    2015-07-01

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

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

    E. Gikonyo

    2010-01-01

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

  9. Aqueous leaching of organic acids and dissolved organic carbon from various biochars prepared at different temperatures.

    Liu, Peng; Ptacek, Carol J; Blowes, David W; Berti, William R; Landis, Richard C

    2015-03-01

    Biochar has been used as a soil amendment, as a water treatment material, and for carbon (C) sequestration. Thirty-six biochars, produced from wood, agricultural residue, and manure feedstocks at different temperatures, were evaluated for the aqueous leaching of different forms of soluble C. The release of inorganic C (alkalinity), organic acids (OAs), and total dissolved organic C (DOC) was highly variable and dependent on the feedstock and pyrolysis temperature. The pH and alkalinity increased for the majority of samples. Higher pH values were associated with high-temperature (high-T) (600 and 700°C) biochars. Statistically significant differences in alkalinity were not observed between low-temperature (low-T) (300°C) and high-T biochars, whereas alkalinity released from wood-based biochar was significantly lower than from others. Concentrations of OAs and DOC released from low-T biochars were greater than from high-T biochars. The C in the OAs represented 1 to 60% of the total DOC released, indicating the presence of other DOC forms. The C released as DOC represented up to 3% (majority biochar. Scanning electron microscopy with energy dispersive X-ray spectroscopy showed the high-T biochars had a greater proportion of micropores. Fourier transform infrared spectroscopy showed that hydroxyl, aliphatic, and quinone were the predominant functional groups of all biochars and that the abundance of other functional groups was dependent on the feedstock. The release of DOC, especially bioavailable forms such as OAs, may promote growth of organisms and heavy metal complexation and diminish the potential effectiveness of various biochars for C sequestration. PMID:26023986

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

    郑东升; 肖松; 梁杰

    2012-01-01

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

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

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

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

    阙绍娟; 陈燕清; 马少健; 何春林

    2011-01-01

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

  13. Environmental aspects of sulphuric acid in situ leach uranium mining in the permafrost zone (Vitim District, Russian Federation)

    Currently in situ leaching pilot tests are in progress at the Khiagda deposit, Vitim District, Russian Federation. The deposit is of the sandstone basal channel type, or paleovalley type in the Russian classification. It contains about 15 000 mt U at an ore grade averaging 0.05% U. Mineralization occurs in permeable unconsolidated Neogene fluvial sediments located below the permafrost which extends to 100 m deep. The basement rock is Paleozoic granite. Neogene-Quaternary basalts overlap the ore hosting sediments. The thickness of the ore host horizon varies from a few meters to 120 m. The depth of mineralization averages 170 m. Ore bodies are of lens and strataform shape. The following types of underground waters have been identified: groundwaters of the near surface or active layer, the aquifer in the Neogene volcanics, the ore host aquifer of the Neogene permeable sediments and fault related waters. The permeability in the ore bearing horizon varies from 0.1 to 20 m/day (averages 2 to 3 m/day). The waters of the productive aquifer are not suitable for industrial nor potable water supply due to their initial chemical composition. The ore host horizons occur between two impermeable horizons, which confine leaching solutions. Using sulphuric acid solutions as leaching reagent decreases the pH and increases Total Dissolved Solids (TDS) of the groundwaters within the leaching area due to concentration of sulphate-ion and other dissolved components. Principal components contaminating the underground waters are sulphates of aluminium, manganese, nickel and chrome. Their content during leaching significantly exceeds initial values. The available information on residual acid migration with the ground water shows that the concentration of contaminants significantly decreases away from the leaching contour. This occurs due to precipitation of contaminants during migration of the underground water from ISL sites. The external contour of the contamination aureole is defined

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

    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

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

    何小凤; 李运刚; 陈金

    2014-01-01

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

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

    Kathryn A. Mumford

    2014-04-01

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

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

    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. PMID:23644591

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

    Smit, Danie Strydom

    2001-01-01

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

  19. Photo-oxidation of gaseous ethanol on photocatalyst prepared by acid leaching of titanium oxide/hydroxyapatite composite

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

    2013-06-01

    Highlights: ► Photocatalyst powder was prepared by acid leaching of TiO{sub 2}/apatite composite. ► The photocatalytic activity was evaluated from in situ FT-IR study using ethanol. ► Apatite in the composite had positive effect for the photo-oxidation of ethanol. ► The enhanced oxidation rate was explained by the difference in deactivation rate. - Abstract: Highly active photocatalysts were synthesized by leaching of heat-treated titanium dioxide (TiO{sub 2})/hydroxyapatite (HAp) powder with hydrochloric acid at 0.25, 0.50, 0.75 mol/l, and their photocatalytic activities were evaluated from in situ Fourier transform infrared (FT-IR) study of photo-oxidation of gaseous ethanol. By changing the acid concentration, the TiO{sub 2}/HAp composite had different atomic ratios of Ca/Ti (0.0–2.8) and P/Ti (0.3–2.1). It was found that phosphate group remained on the surface of TiO{sub 2} particle even in the sample treated with concentrated acid (0.75 mol/l). These acid-treated samples showed higher rates for ethanol photo-oxidation than the commercial TiO{sub 2} powder, Degussa P25. The highest rate was obtained in the TiO{sub 2}/HAp composite treated with the dilute (0.25 mol/l) acid in spite of its low content of TiO{sub 2} photocatalyst. This enhanced photocatalytic activity was attributed to the result that the deactivation with repeated injections of ethanol gas was suppressed in the TiO{sub 2}/HAp composites compared with the TiO{sub 2} powders.

  20. Photo-oxidation of gaseous ethanol on photocatalyst prepared by acid leaching of titanium oxide/hydroxyapatite composite

    Highlights: ► Photocatalyst powder was prepared by acid leaching of TiO2/apatite composite. ► The photocatalytic activity was evaluated from in situ FT-IR study using ethanol. ► Apatite in the composite had positive effect for the photo-oxidation of ethanol. ► The enhanced oxidation rate was explained by the difference in deactivation rate. - Abstract: Highly active photocatalysts were synthesized by leaching of heat-treated titanium dioxide (TiO2)/hydroxyapatite (HAp) powder with hydrochloric acid at 0.25, 0.50, 0.75 mol/l, and their photocatalytic activities were evaluated from in situ Fourier transform infrared (FT-IR) study of photo-oxidation of gaseous ethanol. By changing the acid concentration, the TiO2/HAp composite had different atomic ratios of Ca/Ti (0.0–2.8) and P/Ti (0.3–2.1). It was found that phosphate group remained on the surface of TiO2 particle even in the sample treated with concentrated acid (0.75 mol/l). These acid-treated samples showed higher rates for ethanol photo-oxidation than the commercial TiO2 powder, Degussa P25. The highest rate was obtained in the TiO2/HAp composite treated with the dilute (0.25 mol/l) acid in spite of its low content of TiO2 photocatalyst. This enhanced photocatalytic activity was attributed to the result that the deactivation with repeated injections of ethanol gas was suppressed in the TiO2/HAp composites compared with the TiO2 powders

  1. ACID RAIN - A PROBLEM OF THE PRESENT

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

    1995-01-01

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

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

    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.

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

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

    2014-06-01

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

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

    Youngjin Kim

    2016-08-01

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

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

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

    2016-03-15

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

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

    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.

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

    孙红燕; 森维; 孔馨; 李富宇

    2014-01-01

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

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

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

  9. An integrated experimental-modeling approach to study the acid leaching behavior of lead from sub-micrometer lead silicate glass particles

    Highlights: • Generation of particles by laser ablation of lead silicate glass. • Collection of particles on filters and continuous acid leaching and ICP-MS monitoring. • Fitting of the lead leaching profile to a mathematical intraparticle diffusion model. • Extraction of individual leaching profiles for selected mono-dispersed size fractions. • Leaching kinetics is based on ion-exchange and correlated with particle size. -- Abstract: This work focuses on the development of a procedure to study the mechanism of leaching of lead from sub-micrometer lead glass particles using 0.3 mol l−1 HNO3 as a leachant. Glass particles with an effective size distribution range from 0.05 to 1.4 μm were generated by laser ablation (213 nm Nd:YAG laser) and collected on an inline 0.2 μm syringe filter. Subsequently, the glass particles on the filter were subjected to online leaching and continuous monitoring of lead (Pb-208) in the leachate by quadrupole ICP-MS. The lead leaching profile, aided by the particle size distribution information from cascade impaction, was numerically fitted to a mathematical model based on the glass intraparticle diffusion, liquid film distribution and thermodynamic glass-leachant distribution equilibrium. The findings of the modeling show that the rate-limiting step of leaching is the migration of lead from the core to the surface of the glass particle by an ion-exchange mechanism, governed by the apparent intraparticle lead diffusivity in glass which was calculated to be 3.1 × 10−18 m2 s−1. Lead leaching is illustrated in the form of graphs and animations of intraparticle lead release (in time and intraparticle position) from particles with sizes of 0.1 and 0.3 μm

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

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

    2009-01-01

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

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

    叶钟林; 施哲; 史谊峰; 张邦琪; 代红坤

    2014-01-01

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

  12. Recovery of nickel from spent NiO/Al2O3 catalyst through sulfuric acid leaching, precipitation and solvent extraction.

    Nazemi, M K; Rashchi, F

    2012-05-01

    Effective recovery of nickel (Ni) from spent NiO/Al(2)O(3) catalyst in a simple hydrometallurgical route is suggested. Nickel recovery of 99.5% was achieved with sulfuric acid leaching. The leach liquor was partly neutralized and nickel ammonium sulfate was precipitated by adding ammonia. The nickel in the supernatant was concentrated by solvent extraction using D2EHPA and subsequently stripped back into sulfuric acid and returned to the precipitation stage. Necessary counter current extraction and stripping stages were determined in McCabe-Thiele diagrams. The suggested method appears simple and very effective in recovering nickel from spent catalysts from the petrochemical industry. PMID:21930525

  13. Radionuclide Leaching from Residual Solids Remaining after Acid Dissolution of K East Area Sludge Composite

    Laboratory tests were performed to examine the efficacy of various leach treatments for decontaminating dissolver residual solids (KEACRESID1) produced during a 24-hour dissolution of K East Basin floor and Weasel Pit sludge composite in boiling 6 M HNO3. The scope of this testing has been described in Section 4.5 of ''Testing Strategy to Support the Development of K Basin Sludge Treatment Process'' (Flament 1998). Radionuclides sorbed or associated with the residual solids generated in the K Basin sludge treatment process can restrict disposal of this solid to the Environmental Restoration Disposal Facility (ERDF). The starting dissolver residual solid for this testing, KEACRESID1, is a visibly heterogeneous material. This material contains radionuclides at concentrations above the ERDF Waste Acceptance Criteria for transuranics (TRU) by about a factor of 3, for 239Pu by a factor of 10, and for 241Am by a factor of 1.6. It meets the ERDF criterion for 137Cs by a factor of 4 and for uranium by a factor of 10. Therefore, the radionuclides of greatest interest in this leaching study are first 239Pu, and then 241Am, 137Cs, and uranium

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

    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...

  15. The Effects of Thermal Pretreatment on Leaching of Yunnan Ilmenite with Hydrochloric Acid

    Liu, Song-Li; Xiang, Jun-Yi

    2016-04-01

    The effects of thermal pretreatment on the leaching of Yunnan ilmenite ores were investigated from two aspects: the dissolution of iron and titanium, and the proportion of fine precipitations. The results indicate that high-temperature reduction or oxidization produces phase and structure transformations on ilmenite that facilitate the dissolution of iron, reduce the dissolution of titanium, and facilitate the hydrolysis of dissolved titanium. The results further indicate that oxidation at temperatures ranging from 1023 K (750 °C) to 1273 K (1000 °C) can significantly decrease the proportion of fine products. It is believed that the structure of oxidized ilmenite played an important role in minimizing the proportion of fine materials.

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

    S. C. Vettorazzo

    2001-09-01

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

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

    彭国敏; 俎小凤; 张福元

    2012-01-01

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

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

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

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

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

    2008-03-01

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

  20. Sulphuric acid leaching of low/medium grade managanese ores using a novel nitrogeneous reductant-NH3NH2HSO4

    Hariprasad D.

    2013-01-01

    Full Text Available Low and medium grade land as well sea based manganese ores were used for manganese extraction in H2SO4 - NH3NH2HSO4 (hydrazine sulphate medium For land based Mn ores, only Mn recovery is important but for sea nodules which contain substantial amounts Co, Ni, and Cu, their recovery is equally important. In the present studies four samples used were: Indian ocean manganese nodules, medium and low grade Mn ores of Gujarat, and low grade Mn ore of Orissa, India. The Mn content of these ores varied from 15 to 39%. The objective of this work is to establish a reductant which can be used for leaching Mn from all types of ores. The optimum conditions established for nodules by varying parameters such as time, temperature, pulp density, H2SO4 and NH3NH2HSO4 concentrations were: pulp density 10%, time 0.5h, temperature 110ºC, NH3NH2HSO4 3.25 g/10g, H2SO4 2.0% (v/v for 96.9% Mn, 85.25% Cu, 92.58% Ni and 76.5% Co extractions. More than 92% Mn could be leached from different types of ores by varying amount of reductant and acid concentration at 35ºC. Depending on Mn content 1.0 to 1.2 times stochiometric amount of reductant and 1.5 to 1.8 times sulphuric acid were required for >92% Mn extraction.

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

    易梦雨; 郎婷; 许东东; 孙维义; 丁桑岚; 苏仕军

    2014-01-01

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

  2. Co-fermentation of oil palm lignocellulosic residue with pig manure in anaerobic leach bed reactor for fatty acid production

    Highlights: • Pig manure helped stimulate degradation of EFB in the co-fermentation in ALBR. • High manure mixing and long fermentation time favored VFA production. • Derived quadratic model could satisfactorily explain the relationship of parameters. • Species of fatty acids produced were influenced by flooding interval of reactor bed. - Abstract: Batch experiments were performed to investigate the co-fermentation of palm oil empty fruit bunch (EFB) and pig manure (PM) at various PM mixing ratios (%PM) and flushing intervals (FI) over 60-day fermentation time (FT) using anaerobic leach bed reactors. Addition of PM promoted hydrolysis yield (ηh) and acidification yield (ηa) due to the more degradable and soluble nature of PM that gave out organic acids, and nutrients it supplemented. The highest ηh and ηa found were 27.9 ± 0.3% and 51.7 ± 2.6%, respectively. Longer FI that delayed bed flushing prolonged the dry condition where hydrolytic reaction could be enhanced. The developed multiple regression model with R2 = 0.87 and p < 0.0001 suggested a good fit to the data and able to describe the interactive relationship of the parameters on total volatile fatty acids (VFA) production. The longer chain acids, i.e. propionic (C3), butyric (C4), and valeric (C5) acids, were found in higher concentrations with longer FI and higher pig manure mixing ratios. The mixing of an easier biodegradable pig manure as co-substrate could help induce higher degree of fermentation of the recalcitrant EFB

  3. 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

    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)

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

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

    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.

  6. Kinetics of sulfuric acid leaching of cadmium from Cd-Ni zinc plant residues.

    Safarzadeh, Mohammad Sadegh; Moradkhani, Davood; Ojaghi-Ilkhchi, Mehdi

    2009-04-30

    Cd-Ni filtercakes are produced continuously at the third purification step in the electrolytic production of zinc in the National Iranian Lead and Zinc Company (NILZ) in northwestern Iran. In this research, the dissolution kinetics of cadmium from Cd-Ni residues produced in NILZ plant has been investigated. Hence, the effects of temperature, sulfuric acid concentration, particle size and stirring speed on the kinetics of cadmium dissolution in sulfuric acid were studied. The dissolution kinetics at 25-55 degrees C and tshrinking core model, with inter-diffusion of cadmium and sulfate ions through the porous region of alloying layer (Cd(5)Ni, Cd(2)Ni(1.9) and Cd(10)Cu(3)) as the rate determining step. This finding is in accordance with the apparent activation energy (E(a)) of 13.363 kJ/mol and a linear relationship between the rate constant and the reciprocal of squared particle size. Arrhenius constant was calculated as 6.3942 min(-1). The order of reaction with respect to sulfuric acid concentration, solid/liquid ratio and particle size were also achieved. The rate of reaction at first 5 min based on diffusion-controlled process can be expressed by a semi-empirical equation as:It was determined that the dissolution rate increased with increasing sulfuric acid concentration and decreasing particle size. PMID:18755541

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

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

    2015-11-01

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

  8. Bacteria heap leaching test of a uranium ore

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

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

    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.

  10. Mechanisms controlling the leaching kinetics of fixated flue gas desulfurization (FGD) material under neutral and acidic conditions.

    Cheng, Chin-Min; Walker, Harold W; Bigham, Jerry M

    2007-01-01

    A number of agricultural and engineering uses for fixated flue gas desulfurization (FGD) material exist; however, the potential for leaching of hazardous elements has limited widespread application and the processes controlling the leaching of this material are poorly understood. In this study, a flow-through rotating-disk system was applied to elucidate the relative importance of bulk diffusion, pore diffusion, and surface chemical reaction in controlling the leaching of fixated FGD material under pH conditions ranging from 2.2 to 6.8. Changing the hydrodynamics in the rotating disk system did not affect the leaching kinetics at both pH 2.2 and 6.8, indicating that bulk diffusion was not the kinetic-limiting step. Application of the shrinking core model (SCM) to the data suggested a surface reaction-controlled mechanism, rather than a pore diffusion mechanism. The leaching of fixated FGD material increased with decreasing pH, suggesting it can be described by a combination of an intrinsic hydration reaction and a proton-promoted dissolution reaction. X-ray diffraction (XRD) and elemental composition analyses before and after leaching suggests that for most elements a number of solid phases controlled the leaching process. PMID:17485719

  11. 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.

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

    2016-04-15

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

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

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

    2011-01-01

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

  13. Efficiency of sulfuric acid leaching of the lanthanides as a function of the quality of phosphosemihydrate prepared from Khibin apatite concentrate

    The reasons giving rise to decreased extraction of lanthanides during their sulfuric acid leaching from phosphosemihydrate were studied using the methods of elementary analysis. It was ascertained that main losses of lanthanides stem not from formation of low-soluble rare earth fluorides, but from increased content of sodium and potassium soluble compounds, resulting in deposition of rare earth double sulfates and in violation of semihydrate process

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

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

    2015-01-01

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

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

    贺山明; 王吉坤; 李勇

    2011-01-01

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

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

    李静; 魏世强; 杨学春

    2004-01-01

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

  17. Bicarbonate leaching of uranium

    The alkaline leach process for extracting uranium from uranium ores is reviewed. This process is dependent on the chemistry of uranium and so is independent on the type of mining system (conventional, heap or in-situ) used. Particular reference is made to the geochemical conditions at Crownpoint. Some supporting data from studies using alkaline leach for remediation of uranium-contaminated sites is presented

  18. Leaching of CCBs: observations from over 25 years of research

    David J. Hassett; Debra F. Pflughoeft-Hassett; Loreal V. Heebink [University of North Dakota, Grand Forks, ND (United States). Energy & Environmental Research Center

    2005-08-01

    Leaching of coal combustion by-products (CCBs) using various batch laboratory methods has been ongoing at the Energy & Environmental Research Center for over 25 years. Early on in the various investigations involving leaching it became obvious that the methods being advocated and used were generating scientifically invalid and often misleading data. This realization came about because: 1. The wrong leaching solutions were often being used. Methods such as the extraction procedure toxicity test and, later, the toxic characteristic leaching procedure used an acetic acid-containing solution that would be unlikely to contact CCBs under any conditions. 2. It was found that the formation of secondary hydrated phases such as ettringite could have a profound influence on concentrations of certain trace elements that exist as oxyanions in aqueous solution. Because of these realizations, a method that included long-term leaching (LTL) was developed called the synthetic groundwater leaching procedure, which addressed many of the problems with existing methods. Data collected over the last 25 years will be presented to demonstrate the need for the use of proper leaching solutions and LTL. Additionally, currently utilized and proposed methods will be discussed, including the new suite of leaching methods recently proposed by the US Environmental Protection Agency. 16 refs., 4 figs.

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

    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

  20. Evaluation of alkali fusion and acid leaching methods for the separation of plutonium in fecal samples

    Occupational radiation workers of Fuel reprocessing and Fuel fabrication facilities are monitored for the assessment of intakes of actinide radionuclides and evaluation of effective dose. The determination of the internally deposited radionuclides is carried out, by in-vivo technique, by analyzing the bioassay materials like urine and feaces. Urine samples are selected for the analysis of soluble (Type M) Pu/U isotopes while fecal samples are analyzed for the determination insoluble Pu/U isotopes (Type S). The strategy involves the analysis of both fecal as well as urine samples for assessing the possible nature of compound. This paper presents the investigation of analytical methods for fecal sample processing. Generally, separation of Pu isotopes in fecal sample is carried out by alkali fusion followed by standard radioanalytical technique

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

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

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

    Szymczycha-Madeja, Anna

    2011-02-28

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

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

    曹子宇; 陈永明

    2015-01-01

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

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

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

    2016-05-01

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

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

    孙红燕; 孔馨; 森维; 肖锐敏; 鲁顺利

    2015-01-01

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

  6. Design of thickener for separation of acidic leach liquor from residual solid particles in Bandar Abas uranium plant

    Solid-liquid separation is one of the most important sections in mineral processing. High percentage of clay material and fine particles (-200 mesh) cause different problems in separation of uranium leach liquor from the residual solid particles in filtration unit of Bandar Abbas Uranium Plant. The laboratory tests showed that thickener is a suitable device for solid-liquid separation, after leaching unit. For this reason, thickeners were selected for separating of leach liquor from the residual solid particles. For determination of the size and number of thickeners, sedimentation experiments were performed with different Flocculent, Magna floc LT-25was selected as a suitable Flocculent in 75 g/ton. The diameter of thickener was determined to be 13-14 m. In the counter current decantation, the loss percentage of uranium, using 5 thickeners, was selected to be 2.09%

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

    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

  8. 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

    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.

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

    Smolyaninov, Vladislav; Shekhvatova, Galina; Vainshtein, Mikhail

    2014-01-01

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

  10. Influence of organic amendments on diuron leaching through an acidic and a calcareous vineyard soil using undisturbed lysimeters

    The influence of different organic amendments on diuron leaching was studied through undisturbed vineyard soil columns. Two composts (A and D), the second at two stages of maturity, and two soils (VR and Bj) were sampled. After 1 year, the amount of residues (diuron + metabolites) in the leachates of the VR soil (0.19-0.71%) was lower than in the Bj soil (4.27-8.23%), which could be explained by stronger diuron adsorption on VR. An increase in the amount of diuron leached through the amended soil columns, compared to the blank, was observed for the Bj soil only. This result may be explained by the formation of mobile complexes between diuron and water-extractable organic matter (WEOM) through the Bj soil, or by competition between diuron and WEOM for the adsorption sites in the soil. For both soils, the nature of the composts and their degree of maturity did not significantly influence diuron leaching. - The application of organic amendments increased diuron leaching through a sandy-loam soil, in contrast to a clay-loam soil

  11. Uranium in situ leaching

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

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

    姚倩; 张宇峰; 葛苏苏; 汤传栋; 张慧

    2015-01-01

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

  13. Behaviour of the pH adjustment, Ion exchange and concentrate precipitation stages in the acid leaching of uranium phosphate ores

    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

  14. Measurement of leached hulls

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

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

    韦岩松; 盘有旺

    2013-01-01

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

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

    李栋

    2012-01-01

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

  17. Removal of phosphorus from iron ores by chemical leaching

    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.

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

    Nogueira, C. A.; Paiva, A. P.; P.C. Oliveira; Costa, Maria Clara; Costa, Ana M. Rosa da

    2014-01-01

    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, i...

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

    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.

  20. Application of intensified heap leaching technology of uranium ores to Dabu uranium mine

    In the light of the preliminary design of uranium ore heap leaching for Dabu uranium mine, leaching agent with high concentration of sulfuric acid (about 50 g/L) was used to leach uranium from ores in the initial stage of heap leaching, and then the acidity of leaching agent was gradually reduced according to the concentration of sulfuric acid in leaching solution. Using the leaching agent with low concentration of sulfuric acid to leach uranium in the latter stage leaded to long leaching time, high content of uranium in the leaching residue, and high energy consumption in follow-up producing process. So an intensified heap leaching technology of uranium ores was put forward and adopted to shorten the leaching time and reduce the content of uranium in the leaching residue and the energy consumption. The application of the technology to Dabu uranium mine was introduced, and technical and economic evaluation was carried out. (authors)

  1. 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

    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.

  2. Distribution of Components in Ion Exchange Materials Taken from the K East Basin and Leaching of Ion Exchange Materials by Nitric/Hydrofluoric Acid and Nitric/Oxalic Acid

    Laboratory tests were performed to examine the efficacy of mixed nitric/hydrofluoric acid followed by mixed nitric/oxalic acid leach treatments to decontaminate ion exchange materials that have been found in a number of samples retrieved from K East (KE)Basin sludge. The ion exchange materials contain organic ion exchange resins and zeolite inorganic ion exchange material. Based on process records, the ion exchange resins found in the K Basins is a mixed-bed, strong acid/strong base material marketed as Purolite NRW-037. The zeolite material is Zeolon-900, a granular material composed of the mineral mordenite. Radionuclides sorbed or associated with the ion exchange material can restrict its disposal to the Environmental Restoration Disposal Facility (ERDF). The need for testing to support development of a treatment process for K Basin sludge has been described in Section 4.2 of ''Testing Strategy to Support the Development of K Basins Sludge Treatment Process'' (Flament 1998). Elutriation and washing steps are designed to remove the organic resins from the K Basin sludge. To help understand the effects of the anticipated separation steps, tests were performed with well-rinsed ion exchange (IX) material from KE Basin floor sludge (sample H-08 BEAD G) and with well-rinsed IX having small quantities of added KE canister composite sludge (sample KECOMP). Tests also were performed to determine the relative quantities of organic and inorganic IX materials present in the H-08 K Basin sludge material. Based on chemical analyses of the separated fractions, the rinsed and dry IX material H-08 BEAD G was found to contain 36 weight percent inorganic material (primarily zeolite). The as-received (unrinsed) and dried H-08 material was estimated to contain 45 weight percent inorganic material

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

    李成义; 赵立新; 王志; 郭占成; 王永刚

    2011-01-01

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

  4. Leaching characteristics of a low grade uranium ore

    Leaching characteristics of a low grade uranium ore in Jiangxi province are studied using agitating leaching and column leaching methods. The results of agitating leaching test show that leaching rate of uranium is above 85% under the conditions of sulphuric acid concentration of 10 g/L and stirring 12 h, and the ore is leachable. The results of column leaching test show that leaching rate of uranium is above 85.7% under the conditions of particle size of-5 mm, sulphuric acid dosage of 4.6% (w/w), and leaching time 40 d, and the permeability of ore heap is good (33 L/m2 h). The obtained leaching parameters can be used as the basis of industrial experiment design and adjusting the leaching parameters in production. (authors)

  5. Leaching of concrete : experiments and modelling

    Ekström, Tomas

    2001-01-01

    Many concrete dams, and other concrete structures within the hydropower industry are old and in a more or less severe state of degradation. Leaching is, together with freeze-thaw, the most common degradation problem in Swedish hydraulic concrete structures. This report contains a literature survey of concrete leaching, and presents the results of an experimental determination of leaching.

  6. Zinc leaching from tire crumb rubber.

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

    2012-12-01

    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. PMID:23145882

  7. Extraction of manganese by alkyl monocarboxylic acid in a mixed extractant from a leaching solution of spent lithium-ion battery ternary cathodic material

    Joo, Sung-Ho; Shin, Dongju; Oh, ChangHyun; Wang, Jei-Pil; Shin, Shun Myung

    2016-02-01

    We investigate the separation of manganese by an antagonistic effect from a leaching solution of ternary cathodic material of spent lithium-ion batteries that contain 11,400 mg L-1 Co, 11,700 mg L-1 Mn, 12,200 mg L-1 Ni, and 5300 mg L-1 Li using a mixture of alkyl monocarboxylic acid and di-(2-ethylhexyl)phosphoric acid extractants. pH isotherm, distribution coefficient, separation factor, McCabe-Thiele diagram, selective scrubbing, and countercurrent extraction tests are carried out to prove an antagonistic effect and to recover manganese using alkyl monocarboxylic in the mixed extractant. Slope analysis is used to determine the extraction mechanism between a mixture of extractants and valuable metals. An increasing concentration of alkyl monocarboxylic acid in the mixture of extractants results in a decrease in distribution coefficient of cobalt and manganese, however, the separation factor value (β(Mn/Co)) increases at pH 4.5. This is caused by slope analysis where alkyl monocarboxylic acid disrupts the extraction mechanism between di-(2-ethylhexyl)phosphoric acid and cobalt. Finally, continuous countercurrent extraction in a mini-plant test demonstrate the feasibility of manganese recovery from cobalt, nickel, and lithium.

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

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

    2016-01-01

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

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

    Brenna, J Thomas

    2016-05-01

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

  10. Alternative leaching processes for uranium ores

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

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

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

    2013-01-01

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

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

    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%.

  13. Preparation of tissue engineering porous scaffold with poly(lactic acid) and polyethylene glycol solution blend by solvent-casting/particulate-leaching

    Polyethylene glycol/poly(lactic acid) solution blend is employed as the raw materials to prepare porous scaffold of potential usage in tissue engineering. The solution blend can be naturally introduced in the classical solvent casting/particular leaching technique in porous matrix preparation. The PEG presence is to modify the degradation behavior of scaffolds to fit particular requirements in tissue engineering. The porous matrix of PEG/PLA with various weight ratios are made with pores size ∼250 μm. The SEM characterizations have been done to investigate the porous morphology of products, the results indicate that though with the clear semi-miscibility feature of PEG/PLA blends, the macro-structure is not significantly affected by the PEG content percentage. The degradation results show an enhanced weight loss rate with the presence of PEG as expected. (paper)

  14. Next Generation of Leaching Tests

    A corresponding abstract has been cleared for this presentation. The four methods comprising the Leaching Environmental Assessment Framework are described along with the tools to support implementation of the more rigorous and accurate source terms that are developed using LEAF ...

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

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

    2015-01-01

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

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

    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.

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

    张小云; 覃文庆; 田学达; 陈燕波; 谷雨; 习晓光

    2011-01-01

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

  18. Processing of Malaysian xenotime using the alkaline leaching method

    Apart from being used as a red phosphor in colour television tubes, yttrium is also used as an oxygen detector, optical lenses, advance ceramic materials as well as in the manufacturing of superconductor. Xenotime is a main source of yttrium and is obtained as an industrial by product from tin mining. The present work shows how xenotime is processed by the alkaline leaching method. The results points that the method is comparatively superior than the conventional, namely sulfuric acid leaching. Some of the advantages of the process are purer product, more economics, an environmental friendly by-products and process

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

    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.

  20. Method of continuous pressure leaching of ores

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

  1. Reactive leaching of recovery boiler fly ash

    Frigård, Antti

    2016-01-01

    This thesis studied a new CaO leaching method for chloride and potassium removal from recovery boiler fly ash. The concept of this method is to use calcium oxide (or calcium hydroxide) as an additive in the leaching stage in order to ease the subsequent solid-liquid separation. CaO leaching has several benefits over traditional leaching process which uses sulphuric acid as an additive: CaO does not include sulphur that would affect the mills sulphur sodium balance, CaO is readily available in...

  2. Water monitoring around the Buchim copper mine drainage system and installation for copper leaching

    Konzulov, Gerasim; Sarafiloski, Sare; Serafimovski, Dalibor; Tasev, Goran

    2015-01-01

    In this paper we would like to present ours latest findings in regards to copper contamination around the Buchim copper mine drainage system and adjacent copper leaching facility. Namelly, several so-called polluting hot-spots around the Buchim copper mine have been determined, which manifested pronounced acidic character of mine waters and increased copper concentrations of up to 800 mg/l Cu. After the leaching facility and closed water system were built, the influence of poll...

  3. 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

    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

  4. Direct separation of uranium and thorium from Qatrani phosphatic raw ore by consecutive percolation leaching

    Phosphatic sandstone of Qatrani area contains high concentrations of uranium and thorium (1450 and 870 ppm respectively). These elements were directly separated from a representative sample of the ore by percolation leaching. Separation made was carried out by using two different leaching reagents, citric and nitric acids for obtaining two separate concentrates of U and Th consecutively from the sample. Uranium was leached first by using citric acid where other rock ingredients were left intact. The effects of: (a) increasing acid input amounts and (b) increasing leaching solution volumes (dilution) on U leaching efficiency were studied. The results revealed that citric acid reaction upon phosphate is limited in spite of higher residual acidity reported in the leach liquors. Regarding uranium, its leaching efficiency increased by increasing acid amounts and/or leaching solution volumes while fixing the acid input amounts. The efficiency of U leaching is more pronounced in the second case than in the first. Increasing U leaching while phosphate dissolution is limited could be interpreted as that the relative complexing affinity of citrate anion for hexavalent uranium is by far much greater than with phosphate. Thorium was thereafter leached by using dilute solutions of nitric acid to avoid dissolution of nitric acid to avoid dissolution of impurities. Percolation leaching experiments were thus performed on the uranium-free samples in the columns used previously in uranium leaching. The effects of increasing acid amounts and increasing leach liquor recycles on Th (and P2O5) leaching efficiency were studied

  5. Leaching of Lanthanides from Phosphogypsum Waste using Nonyl Phenol Ethoxylate Associated with HNO3 and HCl

    Mohamed Nouh Kouraim; Mohamed Mohamed Fawzy; Osama Saad Helaly

    2014-01-01

    Leaching of lanthanides from phosphogypsum (PG) was carried out using either free acids such as HCl and HNO3 or these acids associated with Nonyl Phenol Ethoxylate (NPE). The factors affecting the leaching process were optimized. Also the kinetics of the leaching investigated as a function of temperature. Based on the experimental results NPE increased the leaching efficiency by 30 % relative to the corresponding free acids. It was found that the leaching process could be described by a shrin...

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

    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 μg/g U3O8 for ores with an initial content of 2,700 μg/g U3O8. 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 μg/g U3O8 for flotation in one column and 1,100 μg/g U3O8 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)

  7. Computer Modeling of Leaching of Heavy Metal from Cementitious Waste

    Peng Hu

    2013-07-01

    Full Text Available Thermodynamic equilibrium model was used to simulate the results of leaching heavy metal from cementitious wastes. Modeling results of the leached major element concentrations for samples agreed well with the leaching test using the set of pure minerals and solid solutions present in the database. The model revealed Pb and Cd were predominantly incorporated within the calcium silicate hydrate matrix while a greater portion of Cd exist as discrete particles in the cement pores. Precipitation was found to be the dominant mechanism controlling heavy metal solubility with carbonate and silicate species governing the solubility of Pb and carbonate, silicate and hydroxide species governing the solubility of Cd. In the presence of acetic acid, at low pH values Pb and Cd acetate complexes were predominant whereas, at high pH values, hydroxide species dominated. In the presence of municipal landfill leachate, Pb and Cd organic complexes dominated the heavy metal species in solution.

  8. Fractal kinetic model for heap leaching of uranium ore

    By using fractal dimensions of the full particle size distribution instead of average particle size, the analytical models describing heap leaching of uranium ore which were presented by Mellado et al, were improved. Meanwhile, the relationships between the model parameters of the fractal kinetic model for heap leaching of uranium ore and the fractal dimension of uranium ore were determined by column leaching experiments, and then a fractal kinetic model for heap leaching of uranium ore was established, and was further verified by column leaching experiments. The result shows that the fractal kinetic model can well reflect the law of uranium metal leaching of heap leaching of uranium ore. (authors)

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

    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. PMID:25947048

  10. Neptunium Colloidal Behaviors in Present of Humic Acids

    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

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

    Luciano, Randy L; Perazella, Mark A

    2015-01-01

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

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

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

    2014-01-01

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

  13. Leaching of nuclear power reactor wastes forms

    The leaching tests for power reactor wastes carried out at IPEN/CNEN-SP are described. These waste forms consist mainly of spent resins and boric acid concentrates solidified in ordinary Portland cement. All tests were conducted according to the ISO and IAEA recommendations. 3 years leaching results are reported, determining cesium and strontium diffusivity coefficients for boric acid waste form and ion-exchange resins. (Author)

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

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

    2015-12-01

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

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

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

    2015-01-01

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

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

    王永东; 李广悦; 丁德馨; 胡南; 邓钦文; 周支香

    2012-01-01

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

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

    侯栋科; 彭兵; 柴立元; 彭宁; 闫缓; 胡明

    2014-01-01

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

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

    古映莹; 苏莎; 莫红兵; 徐文泱

    2012-01-01

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

  19. Residues leaching from 'Factory of barren ores'

    The objective of the present work is safe management of residues from Factory of Barren Ores, their reprocessing, expenditures reduction for remediation of Istiklol city former uranium tailings. For this purpose, some experiences were adopted - Factory of Barren Ores tailing use for filling up the open pit where water with uranium content 3-5 mg/l is located. Factory of Barren Ores waste are passed through heap leaching and have some amount of uranium salts dissolved in water. Thus, we propose to dissolve uranium from Factory of Barren Ores wastes with uranium bearing water flowing out from gallery and filling up the open-pit by radioactive wastes. In so doing, uranium content flowing out from gallery will increase twice, and further, passing them through apricot's shell, as a sorbent, we will clean the water against radionuclides. Residue samples with uranium content 0,015% from Factory of Barren Ores and uranium bearing waters from gallery 1 with uranium content 0,0025 g/l were used for laboratory tests. After which, a slurry was prepared by means of residue mixing with water in ratio of solid and liquid phases (S:L) - 1:2 and 9,7 ml of sulfuric acid (Ρ=1,82) was added which corresponds consumption by H2SO4 176,54 kg/t. For the first test, leaching was carried out during 4 hours at ph=1,6 at room temperature. For the second test, leaching was carried out at 60deg Cand ph=1,6 during 4 hours. Slurry heating and mixing was carried out by means of magnetic mixer. The basic residue leaching indicators are provided in this article.

  20. 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

    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.

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

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

    2008-05-14

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

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

    张传宝; 颜文斌; 徐辉; 高峰; 华骏

    2012-01-01

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

  3. The development trends of shrinkage stope leaching

    The shrinkage stope leaching is a comprehensive method of mining and hydrometallurgy containing the mining technology (involve developing, cutting, drilling, blasting, caving ore and moving some ores to ground) and leaching ore (include distributing solution, percolation leaching, bottom collecting solution, recovering solution containing metal and processing). Due to integration process, the mining and hydrometallurgy processes are greatly shortened, and the economic profits are very remarkable. The development history of shrinkage stope leaching is presented, and the property of its subject is briefly described. Using several typical examples, its characteristics are summarized and several problems to be resolved are discussed. Finally its development prospect is made

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

    戴曦; 陈田庄; 吴永谦; 周康洁; 李良斌

    2013-01-01

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

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

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

  6. 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

    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.

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

    刘缘缘; 黄自力; 秦庆伟

    2012-01-01

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

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

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

    2016-10-25

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

  9. Studies of leaching of copper ores and flotation wastes

    In Poland, there are significant deposits of copper ores. During the copper extraction, large amounts of flotation wastes are produced. In the ores and flotation wastes many other important elements are present. The main goal of this work was analysis of uranium content and to elaborate procedures for recovery of U from these materials. Two types of ores and four types of waste were examined. It has been found that uranium content varies from 4.5 to 25 ppm. The other elements have also been determined in these materials: Cu (4-5 % in ores and 0.3-1.7 % in waste), Ag, Re, Mo, La, Ni, V, etc. For leaching, sulfuric acid and sodium carbonates of various concentrations (temperature, time) were used. The optimum conditions for leaching have been found. The concentration of uranium in the final solution was generally less than 25 μg/mL. The other elements are also present in the leaching solutions. Simultaneous liquid-liquid extraction of uranium with these elements from leaching solution is under study. In our opinion, only such combined procedure for the recovery of uranium together with the accompanying elements could be cost-effective. (author)

  10. Static leaching of uraniferous shales on open areas

    This report describes the tests on acid heap leaching with conventional (1.400 ppm U3O8) 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)

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

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

    2015-08-01

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

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

    杨俊奎; 徐斌; 杨大锦; 钟宏; 姜涛

    2011-01-01

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

  13. 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

    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.

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

    C. I. NWOYE

    2010-06-01

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

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

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

    2007-01-01

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

  16. The Danish Pesticide Leaching Assessment Programme

    Rosenbom, Annette Elisabeth; Brüsch, Walter Michael; Juhler, Rene K.;

    In 1998, the Danish Parliament initiated the Pesticide Leaching Assessment Programme (PLAP), an intensive monitoring programme aimed at evaluating the leaching risk of pesticides under field conditions. The objective of the PLAP is to improve the scientific foundation for decision-making in the...... Danish regulation of pesticides. The specific aim is to analyse whether pesticides applied in accordance with current regulations leach to groundwater in unacceptable concentrations. The programme currently evaluates the leaching risk of 41 pesticides and 40 degradation products at five agricultural...... report covers the period May 1999-June 2009 and presents the monitoring results from the five agricultural sites presently monitored. The main focus is on evaluating the leaching risk of the pesticides applied during 2007....

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

    可欣; 张昀; 李培军; 李润东

    2009-01-01

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

  18. LEACHING AND SELECTED HYDRAULIC PROPERTIES OF PROCESSED OIL SHALES

    This report describes a column leaching test procedure developed to simulate the leaching of high volume wastes under semi-arid field conditions. The report also presents results obtained when retorted oil shales (Tosco, Paraho, Lurgi) are leached by this procedure. Selected hydr...

  19. A study of extracting uranium by intensified alkaline heap leaching

    A new technique of extracting uranium by intensified alkaline heap leaching was presented to treat a uranium ore of high carbonate content. A lixiviant, high concentration of alkaline solution, reacts with the ore prior to heap making for some time at a certain temperature,reducing the leaching time remarkably. With this technique, the leaching rate of uranium increased from 50% to 90% or above and the leaching time decreased from 64 days to 12 days. (authors)

  20. Uranium leaching and recovery from sandstone ores of Nong Son Basin (Viet Nam)

    Sandstone ores containing uranium in Nong Son area were treated to recover uranium in the form of MDU. These ores are classified into 3 categories depending on the weathering degree, giving different chemical composition as shown. The amount of calcium carbonate (g CaCO3/100g of ore) reacted with HCI under different conditions of temperature and time shows that stirring method requires high acid consumption. The results obtained from static leaching of the 3 ore categories shows that leaching efficiency largely depends on the weathering degree and particle size of ore. The lowest leaching efficiency was observed for non-weathered ore. In order to increase uranium extraction this ore was ground to the size of max. 2.5mm, and then incubated by 40% H2SO4 for 48 hours with the addition of KCIO3 (3 kg/tone of ore) as oxidant. The results of acid pugging showed that uranium extraction efficiency reached min. 92%. The proposed flow-sheet for obtaining yellowcake is presented. The leaching experiments were carried out under the following conditions: Particle size of ore: Weathered: max. 30mm, Semi-weathered: max. 10mm, Non-weathered: max. 2.5mm (incubated by 40% H2SO4); Temperature 25-30 deg. C; Redox potential; pH1, acid consumption: 40-50 kg/ore tone. Leaching efficiency reached 90%. Uranium concentration in the solution after 8-stage counter-current leaching was min. 4 g/L, uranium content in solid waste 0.01%. Leaching solution was filtered and directly neutralized through two stages to precipitate yellowcake. Experimental data showed that the uranium recovery reached 90%. Yellowcake product met the relevant specifications and had U3O8 content of minimum 76%

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

    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 Na2S2O3 and (NH4)2S2O3 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 HNO3were made. The leaching of Au and Ag with alternative reagents: Na2S2O3, and (NH4)2S2O3 in 0.1 M 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

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

    舒聪伟; 唐云; 王在谦; 张覃

    2012-01-01

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

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

    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

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

    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 CO2 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 CO2 (with 10 steps we assessed that the emission of about 90 kg CO2-Eq. could be avoided) thanks to the recovery of indium. This new

  5. Immobilized waste leaching

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

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

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

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

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

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

    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

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

    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

  10. Two stage column leaching of uranium from uraninite ore

    The leaching process of uraninite ore was divided into the acidification and bacterial leaching stages, and the two stage leaching experiments and the control were conducted with 3 columns, each being charged with 20 kg uraninite ore. The ore contained 0.113% uranium, 1.859% iron and large amounts of silica and alumina. In the acidification stage, high to low concentration sulfuric acid solutions were used to acidify the uranium ore in each column until the pH of the pregnant leach solution from each column was maintained at 2.0. The acidification lasted for 18 d and the uranium recoveries for the three columns reached about 70%. In the bacterial leaching stage, column 1, as the control, continued to be leached with sulfuric acid solution with pH=2.0, column 2, with the bacterial solution based on the indirect leaching mechanism, and column 3, with the bacterial solution based on the direct leaching mechanism. The leaching in this stage was continued until the concentrations of the uranium in the pregnant leach solutions from the three columns amounted to less than 50 mg/L. This stage lasted for 20 d and the final uranium recoveries for columns 1, 2 and 3 reached 73.72%, 78.97% and 75.79%, respectively. (authors)

  11. ALKALINE CARBONATE LEACHING PROCESS FOR URANIUM EXTRACTION

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

    1957-11-12

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

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

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

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

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

    2016-01-01

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

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

    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.

  15. Leaching of nuclear power reactor waste forms

    The leaching tests for immobilized power reactor wastes carried out at IPEN are described. These wastes forms consist mainly of spent resins and boric acid concentrates solidified in ordinary Portland cement. All tests were conducted according to the ISO and IAEA recommendations. Three years leaching results are reported. The cesium diffuvity coefficients determined out of these results are about 1 x 10-8 cm2/s for boric acid waste form and 9 x 10-9 cm2/s for ion-exchange resin waste. Strontium diffusivity coefficients found are about 3 x 10-11 cm2/s and 9 x 10-11 cm2/s respectively. (Author)

  16. Main ways and suitable technologies of improving economic benefits for uranium ore heap leaching in China (to be continued)

    Combining with practice of China's uranium ore heap leaching, the author proposes main ways and suitable technologies in the fields of emphasizing feasibility research, adopting strengthened technologies, improving equipment level, optimizing control technological factors and developing application range and so on, which include adopting acid-curry and ferric sulphate-trickle leaching process, bacteria heap leaching, countercurrent heap leaching, selecting advanced material of heap bottom, developing large mechanized heap construction equipment and methods, popularizing drip irrigation distributing solution, optimizing heap leaching process parameters, as well as developing recovery equipment suited to heap leaching, etc, in order to increase leaching rate, reduce heap leaching period and achieve more economic benefits

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

    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

  18. Uranium leaching by fungal metabolite

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

  19. Presentations

    The presented materials consist of presentations of international workshop which held in Warsaw from 4 to 5 October 2007. Main subject of the meeting was progress in manufacturing as well as research program development for neutron detector which is planned to be placed at GANIL laboratory and will be used in nuclear spectroscopy research

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

    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.

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

    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

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

    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. PMID:19157693

  3. Agitation leach experiment of fine ore and high grade concentrate

    Lab experiment and field pilot test were conducted on a slurry from the ore crushing and classification process prior to heap leaching and on a high grade concentrate through ore separation. 96% of uranium extraction can be reached for the slurry ore applying acid leaching. 99% of uranium can be extracted for the concentrate by acid leaching, with the acid consumption being quite high as considerable carbonate associated with the concentrate. While alkaline leaching was applied to the concentrate, only 70% of uranium extraction was approached though the recovery could be enhanced significantly with the temperature increasing. Liquid/solid separation of the leached slurry is feasible through filtration using filter press, with the treatment capacity up to 155 kg/(m2·d) and the washing efficiency over 99%. (authors)

  4. Application of leaching tests for toxicity evaluation of coal fly ash

    Tsiridis, V.; Samaras, P.; Kungolos, A.; Sakellaropoullos, G.P. [Technological Educational Institute for West Macedonia, Kozani (Greece). Dept. for Pollution Control Technology

    2006-08-15

    The toxic properties of coal fly ash samples obtained from various coal combustion power plants were evaluated in this work using physicochemical analyses and bioassays. Physicochemical analyses showed that heavy metals present in solid samples included Cr, Cu, Mn, Ni, Pb, and Zn. The results of the chemical analysis of eluates deduced by the application of standard leaching tests according to EN 12457-2 and Toxicity Characteristic Leaching Procedure (TCLP) methods indicated that the compounds contained in fly ashes could potentially be transferred to the liquid phase depending upon the leaching method used. Heavy metal concentrations were higher in TCLP eluates, indicating that the initial pH value of the leaching medium significantly affected the transfer of these elements to the liquid phase. Tests conducted with the photobacterium Vibrio fischeri (Microtox test), the crustacean Daphnia magna, and the rotifer Brachionus calyciflorus were used to assess toxicity of eluates obtained by both leaching tests. Daphnia magna was the most sensitive test organism. The EN 12457-2 method proved to be more reliable for toxicity evaluation of eluates. In contrast, the TCLP method showed some interference owing to acetic acid toxicity, and precipitation occurred after pH adjustment of eluates from acid to neutral range. The toxicity of both fly ashes and the corresponding solid leaching residues of EN 12457-2 and TCLP leaching tests was also measured using the Microtox Basic Solid phase Test. The results generated with this bioassay indicated that toxicity was greatly influenced by the pH status of the solid samples.

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

    张福元; 俎小凤; 彭国敏

    2013-01-01

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

  6. Leaching technology of uranium in some ore containing several kinds of metallic mineral

    The mineral components and chemical components of the metal mine containing uranium and other kinds of metallic elements are complicated with mineralogy research. The main zinc mineral is Calamine. The main lead mineral is cesarolite. The main manganese minerals are cesarolite and heterolite. The main iron minerals are limonite and hematite. And the main uranium mineral is PbUO4. The leaching technology tests of uranium of the ore are taken. Research shows that the leaching rate of uranium up to 90% with acidic agitation leaching, while it only about 10% with alkaline agitation leaching. And the leaching rate of uranium up to 91.5%, with acidic column leaching to the -5 mm ore sample. While the leaching rate up to 88.4% with the -10 mm ore sample. Therefore, uranium can be used with acid heap leaching technology in the mine. (authors)

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

    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.

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

    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. Carbonate leaching of uranium and hydrogen peroxide stabilizer therefor

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

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

    陈庆根; 黄怀国; 叶志勇; 熊明

    2011-01-01

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

  11. Development and optimisation of process parameters for recovery of uranium from calcia slag and lining material (SLM) by leaching process and subsequent recovery of uranium from the leach liquor generated

    Presently uranium value is recovered by nitric acid dissolution of the SLM, to get uranyl nitrate solution (UNS) and subsequent solvent extraction process. UNS generated After SLM dissolution is very lean in uranium content and create difficulty in solvent extraction. Moreover, NOX is also generated during SLM dissolution in nitric acid. An alternate process was developed where nitric acid is not being used and uranium is being recovered by leaching out the SLM using acetic acid. The process was also optimised for recovery and overall economics of the process by using process effluent AALL (Acetic Acid Leach Liquor) as a leaching agent. The uranium value in the leach liquor was precipitated by using sodium hydroxide. The precipitate was dissolved in nitric acid and the Uranyl Nitrate Solution generated was having Uranium concentration of 15-30 g/l. The alternate process developed will have less effluent generation, less NOX generation and will produce more concentrated UNS in comparison to the nitric acid dissolution process

  12. Leaching from municipal solid waste incineration residues

    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)

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

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

    2014-03-01

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

  14. Leaching and recycling of zinc from liquid waste sediments

    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.

  15. Presentations

    The PARIS meeting held in Cracow, Poland from 14 to 15 May 2007. The main subjects discussed during this meeting were the status of international project dedicated to gamma spectroscopy research. The scientific research program includes investigations of giant dipole resonance, probe of hot nuclei induced in heavy reactions, Jacobi shape transitions, isospin mixing and nuclear multifragmentation. The mentioned programme needs Rand D development such as new scintillations materials as lanthanum chlorides and bromides as well as new photo detection sensors as avalanche photodiodes - such subjects are also subjects of discussion. Additionally results of computerized simulations of scintillation detectors properties by means of GEANT- 4 code are presented

  16. Presentation

    Eduardo Vicente; Rosana de Lima Soares; Eduardo Victorio Morettin

    2013-01-01

    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 ...

  17. YACON INULIN LEACHING DURING HOT WATER BLANCHING

    Caroline Fenner Scher; Adriano Brandelli; Caciano Zapata Noreña

    2015-01-01

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

  18. Study of ground and unground leached vermiculite

    Maqueda, C.; Perez-Rodriguez, J. L.; Šubrt, Jan; Murafa, Nataliya

    2009-01-01

    Roč. 44, 1-2 (2009), s. 178-184. ISSN 0169-1317 Grant ostatní: CICYT(ES) AGL-2005-0164 Institutional research plan: CEZ:AV0Z40320502 Keywords : vermiculite * amorphous silica * acid leaching Subject RIV: CA - Inorganic Chemistry Impact factor: 2.784, year: 2009

  19. Presentation

    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.

  20. Presentation

    Isidor Marí Mayans

    2004-04-01

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

  1. Presentation

    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

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

    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.

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

    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.)

  4. Presentation

    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

  5. Physicochemical bases of underground leaching process

    Physicochemical bases of uranium underground leaching (UL) from ores are considered. The UL process is generally characterized. Advantages and disadvantages of acidic and carbonate leaching techniques are discussed. UO2 oxidation and solution using oxygen and MnO2 as oxidizers in the presence of 3+Fe catalysts and nitrogen oxides, are considered. The data on the solvent interaction with ore and enclosing rock components are given. The mechanisms and kinetic regularities of extracting uranium from ores with natural and artificial permeability are described as well as the mechanisms and kinetic regularities of the process of dissolved uranium absorption by ore-free rocks

  6. Transuranium elements leaching from simulated HLW glasses in synthetic interstitial claywater

    The main objective of this Master Thesis is to measure the steady-state concentrations of Pu, Np, and Am upon the leaching of High-Level Waste Glass in two types of synthetic claywater: humic acid free and humic acid containing synthetic claywater. The synthetic claywater has a composition that is representative for the in-situ interstitial groundwater of the Boom clay formation, a potential geological repository of radioactive waste in Belgium. The steady-state concentrations of transuranium elements were measured by leaching experiments with a typical duration of 400 days. Five main conclusions are drawn from the experimental data. (1) The transuranium elements that are released from simulated High Level Waste Glass are dominantly present in the synthetic claywater solutions as colloids. These colloids are smaller than 2 nm in absence of humic acids. In the presence of humic acids however, the colloids interact with actinides (adsorb or coagulate) and form particles larger than 2 nm. Np and Am are associated with inorganic and organic colloids in the synthetic interstitial claywater solution whereas Pu forms only inorganic colloids. (2) The steady-state concentration of Pu is in good agreement with the solubility of the Pu compound PuO2.xH2O. It is therefore concluded that PuO2.xH2O is the solubility controlling phase. (3) The Pu(IV)-species are dominant in the leaching solutions. Carbonate and humic acid complexes are negligible. (4) The steady-state concentrations of Np and Am in leaching solutions were much lower than the values calculated on the basis of known thermodynamic data. This indicates that the solubility controlling phases for Np and Am were not correctly identified or that the measured Np and Am concentrations were not steady-state values. (5) Non-active glass leaching tests have indicated that no organic colloids were formed as a result of glass dissolution. (A.S.)

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

    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.

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

    徐斌; 钟宏; 王魁珽; 姜涛

    2011-01-01

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

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

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

    2016-01-01

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

  10. 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

    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

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

    胡宇; 彭伟军; 王承二; 宋少先

    2015-01-01

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

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

    Zhiliang Chen

    2016-07-01

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

  13. As Leaching into Fresh Water from Highly Contaminated Hawaiian Soils

    Niklis, N. J.; Rubin, K. H.; El-Kadi, A. I.

    2009-12-01

    Arsenic contamination of current and former agricultural soils in Hawaii is an unfortunate legacy of plantation era agricultural practices. Here, we report an investigation of As mobility in fresh water from highly contaminated (0.8 % As) A-zone Hawaiian andisols from the Hamakua Coast of the Island of Hawai’i. Aliquots of the same acidic soil (pH= 5.0) were exposed to fresh water for varying lengths of time and analyzed to quantify the fraction of As and other elements leached from the soil relative to concentrations determined by total digestion. A maximum of 0.04% of As and 0.05% of Fe were removed from the soils in initial rinses and multi-day leaches using 18 megaohm Millipore water, in experiments lasting up to 35 days. Arsenic concentrations were highest in initial soil rinses, indicating that a small fraction of the total As in the soil is either loosely bound or present as a fine-grained, soluble As-bearing phase. During subsequent leaching experiments, arsenic and most other inorganic ions that we analyzed for reached equilibrium after 3 days; Fe reached equilibrium concentrations after 10 days. All soil solutions contained As levels that exceeded the EPA acceptable drinking water limit of 0.01 ppm. However, contaminant transport modeling suggests that As contaminated leachates would not migrate substantially from this site, so that local isolation and storage of contaminated soils would likely be an acceptable containment method.

  14. Recent Pilot Plant Experience on Alkaline Leaching of Low Grade Uranium Ore in India

    Uranium deposits in India are low grade and are relatively smaller in extent as compared to present worldwide commercial practice. So far, the vein type deposits of Singhbhum Thrust Belt (STB) are being exploited for meeting the Indian requirements of uranium. The deposits are currently processed by acid leaching in the mills located at Jaduguda and Turamdih near Jamshedpur in Jharkhand State of India. The deposits at Jaduguda and Narwapahar are being mined by underground mining and are processed in Jaduguda mill using airagitated Pachucas. The deposits at Banduhurang and Turamdih are being mined by open cast and underground mining respectively and are processed at Turamdih by acid leaching in mechanically agitated reactors. The occurrences of uranium in North East and Northern part of Kadapa basin are relatively moderate in size and are expected to be processed in the near future by acid leaching. Uranium is also found to occur near Tummalapalle in granitic and limestone host rocks in Southern part of Kadapa basin (Andhra Pradesh) and in Gogi in Bhima basin (Karnataka). The deposit in Tummalapalle is relatively lower in grade (≈ 0.042% U3O8) but is a reasonably large reserve, whereas that in Gogi is rich in uranium content (≈0.18% U3O8) but is relatively small reserve. Laboratory tests based on alkaline leaching have been carried out on both types of deposits. Studies for Tummalapalle deposits have been extended to pilot plant level and a complete flow sheet has been established with the regeneration and recirculation of lixiviants and recovery of sodium sulphate as a by-product. The process involves alkaline leaching under oxygen pressure in batch type and/or continuous leach reactor using sodium carbonate/bicarbonate as a leaching media and uranium is recovered as sodium diuranate. Based on the techno-economic evaluation of the process, an industrial scale mill (3 000 tonnes ore/day) is being set up at Tummalapalle in Andhra Pradesh by Uranium Corporation of

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

    Bojinova, Darinka; Teodosieva, Ralitsa

    2016-06-01

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

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

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

    2015-01-01

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

  17. Organic ligands influence leaching kinetics of fixated FGD material

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

    2008-10-15

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

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

    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

  19. Leaching of 210Po in human saliva from smokeless tobacco

    Use of smokeless tobacco (SLT) is associated with cancer of the oral cavity. 210Po, a known carcinogen present in SLT may leach into the saliva when the snuff is held in the mouth. Alpha emission from leached 210Po can cause oral tissue damage, especially in the presence of non healing ulcers seen frequently in snuff users' mouth. Leaching of 210Po from SLT in human saliva was determined for six popular US snuff brands. 210Po was leached into human saliva for 30 min, separated radiochemically and its activity was determined by α-counting. Approximately 2-10% of 210Po present in SLT was observed to leach. Annual exposure from leached 210Po, based on average daily consumption of 15 g of SLT, was calculated to range from 1.1 to 3.8 Bq year-1. (author)

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

    董海刚; 赵家春; 杨海琼; 李博捷; 崔浩

    2014-01-01

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

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

    Hyks, Jiri; Astrup, Thomas; Christensen, Thomas H

    2009-02-15

    Long-term leaching of Ca, Fe, Mg, K, Na, S, Al, As, Ba, Cd, Co, Cr, Cu, Hg, Mn, Ni, Pb, Zn, Mo, Sb, Si, Sn, Sr, Ti, V, P, Cl, and dissolved organic carbon from two different municipal solid waste incineration (MSWI) air-pollution-control residues was monitored during 24 months of column percolation experiments; liquid-to-solid (L/S) ratios of 200-250L/kg corresponding to more than 10,000 years in a conventional landfill were reached. Less than 2% of the initially present As, Cu, Pb, Zn, Cr, and Sb had leached during the course of the experiments. Concentrations of Cd, Fe, Mg, Hg, Mn, Ni, Co, Sn, Ti, and P were generally bellow 1microg/L; overall less than 1% of their mass leached. Column leaching data were further used in a two-step geochemical modeling in PHREEQC in order to (i) identify solubility controlling minerals and (ii) evaluate their interactions in a water-percolated column system over L/S of 250L/kg. Adequate predictions of pH, alkalinity, and the leaching of Ca, S, Al, Si, Ba, and Zn were obtained in a simultaneous calculation. Also, it was suggested that removal of Ca and S together with depletion of several minerals apparently caused dissolution of ettringite-like phases. In turn, significant increase in leaching of oxyanions (especially Sb and Cr) was observed at late stage of leaching experiments. PMID:18583034

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

    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.

  3. Computer Modeling of Leaching of Heavy Metal from Cementitious Waste

    Peng Hu; Wei Dai

    2013-01-01

    Thermodynamic equilibrium model was used to simulate the results of leaching heavy metal from cementitious wastes. Modeling results of the leached major element concentrations for samples agreed well with the leaching test using the set of pure minerals and solid solutions present in the database. The model revealed Pb and Cd were predominantly incorporated within the calcium silicate hydrate matrix while a greater portion of Cd exist as discrete particles in the cement pores. Precipitation w...

  4. Leaching of Cs+ and Co2+ from cement matrix

    To assess the safety for disposal of radioactive cement-waste matrix, the leaching Cs+ and Co2+, has been studied. This paper also presents results from studies made to determine the influence of bentonite and zeolite in immobilization of these metal ions. Leaching tests were carried out in accordance with a method by Hespe during 98 days. From the leaching data the apparent diffusivity of cobalt and cesium in the cement matrix was measured. (author)

  5. A mathematical model for isothermal heap and column leaching

    L.R.P. de Andrade Lima

    2004-01-01

    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...

  6. Modelling the leaching behaviour of an uranium ore

    The leaching behaviour of a uranium ore, with sulfuric acid and sodium chlorate, has been investigated in agitated tanks. Data from conventional leaching studies has been supplemented with mineralogical characterisation and SEM analysis of selected samples. A technique known as block leaching was also used, which allows individual grains of both the ore and gangue minerals to be studied before and after leaching under different conditions. As a result of the experimental investigation a detailed description of the leaching behaviour of the ore has been compiled. The experimental data have been used to prepare a leaching model that describes uranium extraction as a function of residence time, acid strength, temperature and redox potential. In addition, the dissolution behaviour of the key gangue minerals as a function of leaching conditions has been determined. On the basis of ore and gangue mineral dissolution, the consumption of acid has been predicted with good agreement with experimental data. Although the model is largely empirically based, it provides a useful tool for optimising plant operation (author)

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

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

    2016-05-01

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

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

    Saarinen, T.

    2013-01-01

    Abstract 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...

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

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

    2016-08-01

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

  10. In-situ uranium leaching

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

  11. Mineralogical and process controls on the oxidative acid-leaching of radioactive phases in Elliot Lake, Ontario, uranium ores: II - Brannerite and allied titaniferous assemblages

    In representative run-of-mine samples from the Panel and New Quirke mines of the Elliot Lake uranium district, Ontario, brannerite, a metamict uranous titanate, occurs in microscopic grain-aggregates which display wide variations, both in textural habit and in the relative proportions of brannerite, titania polymorphs and/or 'uraniferous titania'. As is widely documented, much of the brannerite occurs as trellis-like arrays of laths and needles pseudomorphing rutile or anatase. In some cases, the laths and needles are cemented by coffinite. Brannerite, with an average composition of (U0.629 Th0.039 Ca0.020) (Ti2.199 Fe0.13)O69 contains ≤3 wt% Th and is distinctly Ti-rich relative to the ideal composition, UTi2O6. Much of the Si reporting consistently in electron microprobe analyses (between 1 wt% and 5 wt%) is tentatively attributed to contamination by the quartz-sericite matrix, and a minor proportion is attributed to the presence of coffinite intergrowths. 'Uraniferous titania' (average partial composition by weight: 10.8% U, 0.3% Th, 32.9% Ti) is considered to represent an intermediate stage in the conversion of titania to brannerite. The leaching behaviour of brannerite in its different modes of occurence was studied qualitatively by the rotating-disc (polished section). (author). 23 refs., 4 tabs., 11 figs

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

    Khoshnevisana A.; Yoozbashizadeha H.

    2012-01-01

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

  13. Leaching Mechanisms Program. Annual report

    The primary goal of this work is to determine the leaching mechanisms of a variety of matrix materials either in use or being considered for the solidification of low-level radioactive wastes by defense and commercial waste generators. Since this program is new and did not formally begin until May of FY 84, the results reported here are few and preliminary. Efforts were concentrated in the following activities: (1) The literature search for leaching data and proposed leaching models and mechanisms for low-level waste. (2) Data base development for leaching data being compiled from the literature and from the leaching experiments in this program. (3) The selection of solidification agents for the experimental part of the program. (4) Fabrication of leach samples and initiation of leach testing. 28 references, 9 figures, 4 tables

  14. DESIGN OF AN EXPERT CONTROL SYSTEM FOR LEACHING PROCESS

    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.

  15. Thermodynamic modeling of the in situ leaching of uranium

    The thermodynamic model of uranium in situ leaching process at the stage of acidification was investigated. It was demonstrated that in the frontal zone of acid leaching solutions reduction of U(VI) up to U(IV) was possible due to the behavior of oxidation-reduction processes with the ferrous ions involved. At the same time uranium is precipitated as U(OH)4. In order to eliminate the negative influence of ferrous iron ions, artificial oxidizers were proposed to be used not only at the stage of active leaching of cells but also at acidification stage of new process cells. (author)

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

    刘水石; 郭宇峰; 邱冠周; 姜涛; 陈凤

    2013-01-01

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

  17. Leaching studies of low-level radioactive waste forms

    A research program has been underway at the Brookhaven National Laboratory to investigate the release of radionuclides from low-level waste forms under laboratory conditions. This paper describes the leaching behavior of Cs-137 from two major low-level waste streams, that is, ion exchange bead resin and boric acid concentrate, solidified in Portland cement. The resultant leach data are employed to evaluate and predict the release behavior of Cs-137 from low-level waste forms under field burial conditions

  18. Leaching studies of low-level radioactive waste forms

    A research program has been underway at the Brookhaven National Laboratory to investigate the release of radionuclides from low-level waste forms under laboratory conditions. This paper describes the leaching behaviour of Cs-137 from two major low-level waste streams, that is, ion exchange bead resin and boric acid concentrate, solidified in Portland cement. The resultant leach data are employed to evaluate and predict the release behaviour of Cs-137 from low-level waste forms under field burial conditions

  19. 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

    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

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

    蒋荣立; 陈文龙; 赵锐先; 王茜

    2012-01-01

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

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

    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.

  2. Study On The Selection Of Leaching System For The Treatment Of Thanh My, Quang Nam Uranium Ore

    In this study, the theoretical and practical basis to select leaching systems for the treatment of uranium ore have been analysed. The treatment of Thanh My low grade uranium ore was investigated using leaching methods including agitation leaching, strong acid pugging and curing, and heap leaching with different technological conditions. Based on data obtained from previous techno-scientific researches in the Institute for Technology of Radioactive and Rare elements, and comparison of experimental results obtained from leaching methods, we have selected the heap leaching method as suitable method for treatment of Thanh My low grade uranium ore. (author)

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

    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 1183 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. - Fertilizers developed from dolomite phosphate rock (DPR) reduce phosphorus leaching from sandy soil

  4. Organic acid enhanced soil risk element (Cd, Pb and Zn) leaching and secondary bioconcentration in water lettuce (Pistia stratiotes L.) in the rhizofiltration process.

    Veseý, Tomás; Tlustos, Pavel; Száková, Jirina

    2012-04-01

    The use of natural chelates to enhance risk element mobility combined with rhizofiltration by free floating macrophytes have not been thoroughly studied in recent years. The aim of this study was to investigate the efficiency of organic acids in soil by conducting flushing experiments to enhance the mobility of Cd, Pb, and Zn from soil to solution. In addition, the bioaccumulation of Cd, Pb, and Zn, in water lettuce (Pistia stratiotes L.) will be studied as they affect the biomass in the rhizofiltration process. The results revealed that citric and tartaric acids mobilised the highest amount of all risk elements. In comparison to control, citric acid mobilised 71%, 181%, and 112% of Cd, Pb, and Zn while tartaric acid mobilised 70%, 155%, and 135% of Cd, Pb, and Zn respectively. The bioconcentration factor was approximately 2-5 times higher for juvenile plants than mature plants for all treatments as well as for both parts (leaves and roots). The risk element translocation into aerial parts decreased with increased time. Juvenile and mature plants proved a high accumulation potential and a 3 week growth period was observed as a sufficient time period to remove more than 80% of Cd, Pb, and Zn. PMID:22567715

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

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

    2000-01-01

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

  6. Dynamics of aluminum leaching from water purification sludge.

    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. PMID:22459977

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

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

  8. Leaching of polycyclic aromatic hydrocarbons from new and reclaimed asphalt pavements

    Legret, M.; ODIE, L; DEMARE, D; MONERON, P; Jullien, A.

    2005-01-01

    This work presented herein displays the results of a study addressing environmental concerns related to the possible leaching of pollutants from new and reclaimed asphalt pavement. Samples from an experimental site were tested in both static batch tests and columns leaching tests. Selected polycyclic aromatic hydrocarbons (PAHs) were analysed in leachates. The results have allowed us to consider the leaching of pollutants to be rather weak. Concentrations in solutions from batch leaching test...

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

    Smolyaninov, Vladislav; Shekhvatova, Galina; Vainshtein, Mikhail

    2014-01-01

    The article present a review on own experimental and some published data which are related with the gold leaching. It is well-known that the most common and usual process of the leaching with cyanide can be dangerous, needs a great water consumption, and additional costs for remediation of the poisoned and toxic sites. The experimental data described production of poythionates which are not toxic but perspective for the prosperous gold leaching. The paper dedicated to the safe gold leaching w...

  10. Recovery of lanthanides and yttrium from red mud by selective leaching

    This study presents a rapid and selective method for the recovery of lanthanides and yttrium, existing in economically interesting concentrations, from red mud, the byproduct of the alumina production. The leaching process is based on the extraction of these elements with diluted nitric acid from red mud under moderate conditions and without using any preliminary treatment. Several parameters such as leaching agents, contact time, temperature, pressure and solid to liquid ratio were investigated in order to achieve an optimum recovery. The process followed here was selected taking into account its efficiency for the selective recovery of yttrium and lanthanides, but also its suitability for the subsequent liquid-liquid extraction of the leaching solution for the separation of the individual lanthanides. The achieved recovery percentages were for Y about 90%, for the investigated heavy lanthanides (Dy, Er, Yb) up to 70%, for the middle ones (Nd, Sm, Eu, Gd) up to 50% and for the group of light lanthanides (La, Ce, Pr) up to 30%. Most of the main elements of the red mud and especially iron are hardly dissolved by this leaching process, leading to an interference free determination of the lanthanides and yttrium in the leachate by inductively coupled plasma-atomic emission spectroscopy (ICP-AES)

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

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

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

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

    2015-09-01

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

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

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

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

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

    2015-01-01

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

  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

    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. Static Leaching of Spanish Uranium Ores

    The paper summarizes the experience acquired in Spain during seven years of investigation on the static leaching of uranium ores. The operations covered minerals showing wide variations with regard to both uranium content (250 and 2000 ppm) and the type of rock and gangue (granites, shales, sandstones, sulphides, carbonates, limonites etc. ). The studies were carried out on quantities of material varying from a few kilograms to several tons. Leaching agents included water, solid reagents (pyrites), alkaline carbonates and sulphuric acid. The systems used consisted of both simple layouts and other, more elaborate schemes including recycling of the liquors. The uranium was recovered from the liquors first by direct precipitation and later by ion-exchange and extraction with amines. (author)

  17. Static leaching of Spanish uranium ores

    The paper summarizes the experience acquired in Spain during seven years of investigation on the static leaching of uranium ores. The operations covered minerals showing wide variations with regard to both uranium content (250 and 2000 ppm) and the type of rock and gangue (granites, shales, sandstones, sulphides, carbonates, limonites etc.). The studies were carried out on quantities of material varying from a few kilograms to several tons. Leaching agents included water, solid reagents (pyrites), alkaline carbonates and sulphuric acid. The systems used consisted of both simple layouts and other, more elaborate schemes including recycling of the liquors. The uranium was recovered from the liquors first by direct precipitation and later by ion-exchange and extraction with amines. (author)

  18. Leaching of RA-226 contaminated gravel using different aqueous treatments

    Investigation of the efficiencies of different aqueous leaching treatments was carried out on gravel artificially contaminated with Ra-226. The extent of leaching efficiency was determined in terms of Ra-226 and its daughter Rn-222. Liquid scintillation counting using high efficiency mineral oil based liquid scintillator was the technique adopted for measuring Ra-226 and Rn-222 leached off the contaminated gravel. Water, dilute solutions of barium chloride and HCl were used as leachants. Different masses of gravel were leached with 200 mL of leachant for various contact time periods. The leached Rn-222 activity measured was plotted vs the decay factor e; from which Rn-222 and Ra-226 originally present in the sample were determined. Several leaching parameters were tested; namely type of leachant, leachant volume/gravel mass ratio, leachant contact time, effect of varying Ba Cl2 concentration, and successive leaching. Optimization of the leaching parameters for desorption of Ra-226 off the contaminated gravel under laboratory conditions may help determine the ideal conditions for remediating soil contaminated with radium or chemically similar radionuclides. 7 figs

  19. 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

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

  20. Radiocesium leaching from contaminated litter in forest streams

    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. - Highlights: • Radiocesium in contaminated litter was leached when soaked in water. • Radiocesium in litter leached slowly compared to potassium. • Minerals adsorbed dissolved radiocesium that was leached from litter. • Vermiculite effectively adsorbed radiocesium leached from litter

  1. Coupling leaching of sphalerite concentrate

    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.

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

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

    2010-01-01

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

  3. Defining Effective Salt Leaching Regions Between Drains

    ANAPALI, Ömer; ŞAHİN, Üstün; Öztaş, Taşkın; Hanay, Abdurrahman

    2001-01-01

    The application of sufficient amounts of leaching water by means of an effective method is very important in the management and reclamation of saline and sodic soils. Reclamation cannot be achieved with insufficient leaching water application, while excess water application may cause severe problems in soil. Knowledge of the leaching regions and intensities may help to control the amounts of leaching water through effective leaching methods in areas of limited leaching. This study was und...

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

    Xu, Ying; Chen, Yu

    2015-07-01

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

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

    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.

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

    Bolat Uralbekov; Mukhambetkaly Burkitbayev; Bagdat Satybaldiev

    2015-01-01

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

  7. 300 Area Uranium Leach and Adsorption Project

    The objective of this study was to measure the leaching and adsorption characteristics of uranium in six near-surface sediment samples collected from the 300 Area of the Hanford Site. Scanning electron micrographs of the samples showed that the uranium contamination in the sediments is most likely present as co-precipitates and/or discrete uranium particles. Molecular probe techniques also confirm the presence of crystalline discrete uranium bearing phases. In all cases, the uranium is present as oxidized uranium (uranyl [U(VI)]). Results from the column leach tests showed that uranium leaching did not follow a constant solubility paradigm. Four of the five contaminated sediments showed a large near instantaneous release of a few percent of the total uranium followed by a slower continual release. Steady-state uranium leachate concentrations were never measured and leaching characteristics and trends were not consistent among the samples. Dissolution kinetics were slow, and the measured leach curves most likely represent a slow kinetically controlled desorption or dissolution paradigm. Batch adsorption experiments were performed to investigate the effect of pH and uranium and carbonate solution concentrations on uranium adsorption onto the uncontaminated sediment. Uranium adsorption Kd values ranged from 0 to > 100 ml/g depending on which solution parameter was being adjusted. Results of the experiments showed that carbonate solution concentration has the greatest impact on uranium adsorption in the 300 Area. Solution pH was shown to be important in laboratory tests; however, the sediment will dominate the field pH and minimize its overall effect in the 300 Area sediments. Results also showed that uranium sorption onto the background sediment is linear up to uranium concentrations of 3 mg/L, well above the values found in the upper unconfined aquifer. Therefore, the linear Kd model is defensible in predicting the fate of uranium in the 300 Area aquifer

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

    吕建军; 肖连生; 张启修; 黄芍英; 胡磊; 曾之琪

    2013-01-01

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

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

    Jin-Young Lee

    2013-06-01

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

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

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

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

    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)

  12. Chemical leaching methods and measurements of marine labile particulate Fe

    Revels, B. N.; John, S.

    2012-12-01

    Iron (Fe) is an essential nutrient for life. Yet its low solubility and concentration in the ocean limits marine phytoplankton productivity in many regions of the world. Dissolved phase Fe (0.4μm) may contain an important, labile reservoir of Fe that may also be available to phytoplankton. However, concentration data alone cannot elucidate the sources of particulate Fe to the ocean and to what extent particulate iron may support phytoplankton growth. Isotopic analysis of natural particles may help to elucidate the biogeochemical cycling of Fe, though it is important to find a leaching method which accesses bioavailable Fe. Thirty-three different chemical leaches were performed on a marine sediment reference material, MESS-3. The combinations included four different acids (25% acetic acid, 0.01M HCl, 0.5M HCl, 0.1M H2SO4 at pH2), various redox conditions (0.02M hydroxylamine hydrochloride or 0.02M H2O2), three temperatures (25°C, 60°C, 90°C), and three time points (10 minutes, 2 hours, 24 hours). Leached Fe concentrations varied from 1mg/g to 35mg/g, with longer treatment times, stronger acids, and hotter temperatures generally associated with an increase in leached Fe. δ56Fe in these leaches varied from -1.0‰ to +0.2‰. Interestingly, regardless of leaching method used, there was a very similar relationship between the amount of Fe leached from the particles and the δ56Fe of this iron. Isotopically lighter δ56Fe values were associated with smaller amounts of leached Fe whereas isotopically heavier δ56Fe values were associated with larger amounts of leached Fe. Two alternate hypotheses could explain these data. Either, the particles may contain pools of isotopically light Fe that are easily accessed early in dissolution, or isotopically light Fe may be preferentially leached from the particle due to a kinetic isotope effect during dissolution. To explore the first hypothesis, we modeled dissolution of Fe from particles assuming two separate pools, labile

  13. Refractory status epilepticus and glutamic acid decarboxylase antibodies in adults: presentation, treatment and outcomes.

    Khawaja, Ayaz M; Vines, Brannon L; Miller, David W; Szaflarski, Jerzy P; Amara, Amy W

    2016-03-01

    Glutamic acid decarboxylase antibodies (GAD-Abs) have been implicated in refractory epilepsy. The association with refractory status epilepticus in adults has been rarely described. We discuss our experience in managing three adult patients who presented with refractory status epilepticus associated with GAD-Abs. Case series with retrospective chart and literature review. Three patients without pre-existing epilepsy who presented to our institution with generalized seizures between 2013 and 2014 were identified. Seizures proved refractory to first and second-line therapies and persisted beyond 24 hours. Patient 1 was a 22-year-old female who had elevated serum GAD-Ab titres at 0.49 mmol/l (normal: partial seizure control. Patient 2 was a 61-year-old black female whose serum GAD-Ab titre was 0.08 mmol/l. EEG showed persistent generalized periodic discharges despite maximized therapy with anticonvulsants but no immunotherapy, resulting in withdrawal of care and discharge to nursing home. Patient 3 was a 50-year-old black female whose serum GAD-Ab titre was 0.08 mmol/l, and was discovered to have pulmonary sarcoidosis. Treatment with steroids and intravenous immunoglobulin resulted in seizure resolution. Due to the responsiveness to immunotherapy, there may be an association between GAD-Abs and refractory seizures, including refractory status epilepticus. Causation cannot be established since GAD-Abs may be elevated secondary to concurrent autoimmune diseases or formed de novo in response to GAD antigen exposure by neuronal injury. Based on this report and available literature, there may be a role for immuno- and chemotherapy in the management of refractory status epilepticus associated with GAD-Abs. PMID:26878120

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

    Minić Duško

    2004-01-01

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

  15. Economic leaching at Roessing Uranium Limited

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

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

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

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

    Novak, Martin, E-mail: martin.novak@geology.cz [Czech Geological Survey, Geologicka 6, 152 00 Prague 5 (Czech Republic); Pacherova, Petra; Erbanova, Lucie [Czech Geological Survey, Geologicka 6, 152 00 Prague 5 (Czech Republic); Veron, Alain J. [CEREGE UMR CNRS, Universite Aix-Marseille, Europole Mediterraneen, BP80 Plateau Petit Arbois, 13545 Aix en Provence (France); Buzek, Frantisek; Jackova, Ivana; Paces, Tomas; Rukavickova, Lenka; Blaha, Vladimir; Holecek, Jan [Czech Geological Survey, Geologicka 6, 152 00 Prague 5 (Czech Republic)

    2012-10-15

    Highlights: Black-Right-Pointing-Pointer S and Pb isotopes are useful tracers of polluted groundwater movement. Black-Right-Pointing-Pointer Large ranges of found {delta}{sup 34}S and {sup 206}Pb/{sup 207}Pb ratios made source apportionment robust. Black-Right-Pointing-Pointer {delta}{sup 34}S values higher than 6.5 permil indicated contamination. Black-Right-Pointing-Pointer Pb in stream sediment recorded landfill leaks, but was insensitive to air pollution. Black-Right-Pointing-Pointer The front of polluted groundwater plume in fractured plutonic rocks spread unevenly. - Abstract: Slightly elevated concentrations of toxic species in waters sampled in the surroundings of a leaky landfill may be both a sign of an approaching contaminant plume, or a result of water-rock interaction. Isotopes can be instrumental in distinguishing between anthropogenic and geogenic species in groundwater. We studied sulfur and lead isotope ratios at an abandoned industrial-waste landfill, located in a densely populated part of Central Europe. Stable isotope variability in space and time was used to follow the movement of a groundwater plume, contaminated with toxic metals (Cd, Cr, Be), in fractured granitoids. Toxic metals had been mobilized from industrial waste by a strong pulse of sulfuric acid, also deposited in the landfill. Both tracers exhibited a wide range of values ({delta}{sup 34}S between +2.6 and +18.9 Per-Mille-Sign ; {sup 206}Pb/{sup 207}Pb between 1.16 and 1.39), which facilitated identification of mixing end-members, and made it possible to assess the sources of the studied species. In situ fractionations did not hinder source apportionment. Influx of contaminated groundwater was observed neither in irrigation wells in a nearby village, nor at distances greater than 300 m from the landfill. Combination of stable isotope tracers can be used as part of an early-warning system in landscapes affected by landfills.

  18. Lysimeter study of commercial reactor waste forms: waste form acquisition characterization and full-scale leaching

    This report describes work conducted at Brookhaven National Laboratory (BNL) as part of a joint program with Savannah River Laboratory. Typical full-scale (55-gallon drum size) waste forms were acquired by BNL from a boiling water reactor (BWR) and a pressurized water reactor (PWR). Liquid waste stream activity concentrations were analyzed by gamma spectroscopy. This information was used to determine the waste from activity inventory, providing the necessary source term for lysimeter and leaching experiments. Predominant radionuclides of interest include 60Co, 137Cs, 134Cs, and 54Mn. A full-scale leaching experiment was initiated by BNL encompassing four representative waste stream-solidification agent combinations. Waste streams tested include PWR evaporator concentrate (boric acid waste), BWR evaporator concentrate (sodium sulfate waste) and BWR evaporator concentrate plus ion exchange resins. Solidification agents include masonry cement, portland type III cement, and vinyl ester-styrene (Dow polymer). Analyses of leachates indicate measurable leach rates of 137Cs, 134Cs, and 60Co from both BWR and PWR cement waste forms. The leach rates for both cesium isotopes in cement are at least two orders of magnitude greater than those for cobalt. Leachates from the BWR Dow polymer waste form include the same isotopes present in cement leachates, with the addition of 54Mn. Cesium leach rates from the Dow polymer waste form are approximately one order of magnitude lower than from an equivalent cement waste form. The 60Co cumulative fraction release, however, is approximately three times greater for the Dow polymer waste form

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

    Khoshnevisana A.

    2012-01-01

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

  20. Leaching of concrete : the leaching process : extrapolation of deterioration : effect on the structural stability

    Fagerlund, Göran

    2000-01-01

    The leaching process when water attacks concrete, and the effect of leaching on the strength and durability of a concrete structure, is analysed theoretically. Technique for prediction of the future leaching and structural stability is outlined. The analysis is to a certain extent supported by data from literature. The leaching process is divided in five different types: 1: Pure surface leaching 2: Surface leaching involving erosion 3: Homogeneous leaching over the entire structure 4...

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

    温春辉; 刘祖文; 张念; 徐春燕; 张旭东

    2016-01-01

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

  2. Genotoxicity evaluation of kaurenoic acid, a bioactive diterpenoid present in Copaiba oil.

    Cavalcanti, B C; Costa-Lotufo, L V; Moraes, M O; Burbano, R R; Silveira, E R; Cunha, K M A; Rao, V S N; Moura, D J; Rosa, R M; Henriques, J A P; Pessoa, C

    2006-03-01

    Copaiba oil extracted from the Amazon traditional medicinal plant Copaifera langsdorffii is rich in kaurenoic acid (ent-kaur-16-en-19-oic acid), a diterpene that has been shown to exert anti-inflammatory, hypotensive, and diuretic effects in vivo and antimicrobial, smooth muscle relaxant and cytotoxic actions in vitro. This study evaluated its potential genotoxicity against Chinese hamster lung fibroblast (V79) cells in vitro, using the Comet and the micronucleus assays. Kaurenoic acid was tested at concentrations of 2.5, 5,10, 30 and 60 microg/mL. The positive control was the methylmethanesulfonate (MMS). The duration of the treatment of V79 cells with these agents was 3h. The results showed that unlike MMS, kaurenoic acid (2.5, 5, and 10 microg/mL) failed to induce significantly elevated cell DNA damage or the micronucleus frequencies in the studied tests. However, exposure of V79 cells to higher concentrations of kaurenoic acid (30 and 60 microg/mL) caused significant increases in cell damage index and frequency. The data obtained provide support to the view that the diterpene kaurenoic acid induces genotoxicity. PMID:16182426

  3. Study on leaching of refractory uranium in clay

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

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

    Weber, Paula D.; Gutierrez, Karen A.; Lord, David L.; Rudeen, David Keith [GRAM, Inc., Albuquerque, NM

    2013-09-01

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

  5. Chemo-mechanical coupling behaviour of leached concrete

    Nguyen, V.H. [Laboratoire d' Analyse des Materiaux et Identification, Ecole Nationale des Ponts et Chaussees, Institut Navier, 6 et 8, Avenue Blaise Pascal, 77455 Marne la Vallee Cedex 2 (France); Colina, H. [ATILH, 7, Place de la Defense, 92974 Paris-La-Defense Cedex (France); Torrenti, J.M. [LCPC Paris, 58, Boulevard Lefebvre 75732 Paris Cedex 15 (France); LMT, ENS Cachan, 61, Avenue du President Wilson, 94235 Cachan (France)], E-mail: jean-michel.torrenti@ponts.org; Boulay, C. [LCPC Paris, 58, Boulevard Lefebvre 75732 Paris Cedex 15 (France); Nedjar, B. [Laboratoire d' Analyse des Materiaux et Identification, Ecole Nationale des Ponts et Chaussees, Institut Navier, 6 et 8, Avenue Blaise Pascal, 77455 Marne la Vallee Cedex 2 (France)

    2007-11-15

    This paper deals with concrete behaviour under chemical and mechanical degradations. Experimental investigations are described where the effects of the calcium leaching process of concrete on its mechanical properties are highlighted. The calcium leaching and mechanical tests on cement paste, mortar and concrete samples are presented. Because of the slow kinetics of leaching under deionised water, an accelerated method has been chosen by using an ammonium nitrate solution instead. The specimens are immersed into a 6 mol/l ammonium nitrate solution with a controlled pH disposal. To quantify the leaching evolution, the degradation depth is then measured at certain time intervals by means of a phenolphthalein solution. The experimental results show the chemical degradation of the cement-based material and the important role of aggregate in the calcium leaching process of concrete. Compression tests of concrete samples are also performed. We observe that there is a strong coupling between the calcium leaching and the mechanical behaviour; as leaching grows, a loss of stiffness and of strength are observed and a smoother post-peak behaviour is noted.

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

    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.

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

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

    2009-01-01

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

  8. Combining sulfate electrowinning with chloride leaching

    Fletcher, A. W.; Sudderth, R. B.; Olafson, S. M.

    1991-08-01

    Although the chloride leaching of copper sulfide concentrates has proved highly efficient, electrowinning from chloride solutions presents many difficulties, notably in cell design and the handling of the powder product. Sulfate electrowinning,on the other hand, continues to improve and has played a significant part in the widespread adoption of the solvent extraction-electrowinning process for copper recovery from low-grade ores. It has been found that the two steps can be combined by introducing a novel solvent extraction process after chloride leaching. This article presents the results of laboratory tests to prove the feasibility of this approach and discusses how it can be integrated into a commercially viable flow sheet.

  9. Leaching characteristics of paraffin waste forms generated from Korean nuclear power plants.

    Kim, J Y; Kim, C L; Chung, C H

    2001-01-01

    Leaching tests of paraffin waste forms including boric acid, cobalt, strontium and cesium were performed to investigate the leaching characteristics of paraffin waste forms which had been generated in Korean nuclear power plants. The leaching tests were conducted according to ANSI/ANS-16.1 test procedure and the cumulative fractions leached (CFLs) of boric acid, cobalt, strontium and cesium were obtained. The compressive strength before and after the leaching test was measured for various waste forms with different mixing ratios of boric acid to paraffin. It was observed that boric acid and other nuclides immobilized within paraffin waste forms were congruently released and the leaching rates were influenced by reacted layer depth as the dissolution reaction progressed. A shrinking core model based on the diffusion-controlled dissolution kinetics was developed in order to simulate the test results. The CFLs and the leaching rates were well expressed by the shrinking core model and the cross-sectional view of specimen after the test demonstrated the applicability of this model with the shrinking dissolution front to the leaching analysis of paraffin waste forms. PMID:11300532

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

    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.

  11. Extended Leach Testing of Simulated LAW Cast Stone Monoliths

    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.

  12. Extended Leach Testing of Simulated LAW Cast Stone Monoliths

    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.

  13. Exploration on trickle leaching of uranium ore by refreshed liquor of bacterial oxidation

    The paper describes the adaptation of the domesticated thiobacillus ferroxidans to the trickle leaching conditions of uranium ore. When the bacterial leaching liquor through multiple cycles of oxidation and regeneration was used to return to the trickle leaching, the following results were obtained: the extraction rate was more than 95%, the acid consumption was saved by 30%, and the consumed 2.0% pyrolusite (MnO240%) was eliminated. The following problems are discussed: the basic principle, process and some factors influencing the process of the trickle leaching of uranium ore using regenerated liquor of bacterial oxidation, counter-current trickle leaching mode, oxidation and regeneration techniques of bacterial leaching liquor and other technological problems on the process of uranium extraction by thiobacillus ferroxidans

  14. The effects of pH and buffer materials on the leaching of simulated waste glass

    Effects of pH, bentonite Portland cement on the leaching of the simulated waste glass were investigated. The simulated waste glass showed the low leach rate in the neutral pH region, which the leach rate in both acidic and alkaline regions increased. Addition of bentonite to the leachant enhanced the leaching of the waste glass. When the waste glass was leached at 72 deg c for 36 days in the ground water with gel state Na-bentonite, approximately 2.2 μm of the surface was corroded out and the large amount of Ti, Nd, and Zr was observed on the surface. The amount of B leached from the simulated waste glass in the presence of domestic bentonite was about three times higher than that in the presence of Aldrich bentonite as well as Portland cement. (author)

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

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

    2016-03-01

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

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

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

    2008-11-15

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

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

    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.

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

    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 .

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

    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)

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

    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).

  1. Separation of uranium from solid (U, Pu, Ag) oxide analytical waste: effect of batch size and nitric acid molarity

    Earlier we had studied the effect of leaching of a solid analytical waste of (U,Pu)O2 and AgCl with nitric acid of different molarities for identical as well as varying time intervals and the effect of leaching of this waste with nitric acid as a function of batch size (5,10, 20 g). In the present work, the effect of multistep leaching of a 25 g lot of this analytical waste with 4 and 8 M HNO3 was studied. The concentrations of U, Pu and silver were determined using ICP-AES. The results are discussed in this report. (author)

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

    Nazanin Samadifard

    2015-11-01

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

  3. Production of organic acids by periplasmic enzymes present in free and immobilized cells of Zymomonas mobilis.

    Malvessi, Eloane; Carra, Sabrina; Pasquali, Flávia Cristina; Kern, Denise Bizarro; da Silveira, Mauricio Moura; Ayub, Marco Antônio Záchia

    2013-01-01

    In this work the periplasmic enzymatic complex glucose-fructose oxidoreductase (GFOR)/glucono-δ-lactonase (GL) of permeabilized free or immobilized cells of Zymomonas mobilis was evaluated for the bioconversion of mixtures of fructose and different aldoses into organic acids. For all tested pairs of substrates with permeabilized free-cells, the best enzymatic activities were obtained in reactions with pH around 6.4 and temperatures ranging from 39 to 45 °C. Decreasing enzyme/substrate affinities were observed when fructose was in the mixture with glucose, maltose, galactose, and lactose, in this order. In bioconversion runs with 0.7 mol l(-1) of fructose and with aldose, with permeabilized free-cells of Z. mobilis, maximal concentrations of the respective aldonic acids of 0.64, 0.57, 0.51, and 0.51 mol l(-1) were achieved, with conversion yields of 95, 88, 78, and 78 %, respectively. Due to the important applications of lactobionic acid, the formation of this substance by the enzymatic GFOR/GL complex in Ca-alginate-immobilized cells was assessed. The highest GFOR/GL activities were found at pH 7.0-8.0 and temperatures of 47-50 °C. However, when a 24 h bioconversion run was carried out, it was observed that a combination of pH 6.4 and temperature of 47 °C led to the best results. In this case, despite the fact that Ca-alginate acts as a barrier for the diffusion of substrates and products, maximal lactobionic acid concentration, conversion yields and specific productivity similar to those obtained with permeabilized free-cells were achieved. PMID:23053345

  4. Leaching of trace elements from coal solid waste

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

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

    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.

  6. 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

    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.

  7. Adequate drainage system design for heap leaching structures.

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

    2007-08-17

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

  8. Designing leaching fields in Straz deposit

    The deposit contains several types of ores differing in permeability and leachability. A network of survey bores offers basic design information. Using the data obtained, the description is produced of the geotechnological structure of the deposit. Kinetic functions of sulfuric acid reaction with ore are determined for each layer. The design also requires information on tectonics, hydraulic conditions in the whole area and on economic parameters. The results of the calculations can provide information on the quality of the leachate, production, acid consumption; using prices and other economic data, costs for different seasons and years elapsing from the beginning of the leaching process can be calculated. The model is demonstrated on an example of optimization of one mining field. (M.D.). 10 figs., 10 refs

  9. Quasi-dynamic leaching characteristics of polychlorinated dibenzo-p-dioxins and dibenzofurans from raw and solidified waste incineration residues.

    Hsi, Hsing-Cheng; Wang, Lin-Chi; Yu, Tsung-Hsien; Chang-Chien, Guo-Ping

    2008-03-01

    Quasi-dynamic leaching characteristics of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) from raw and solidified air pollution control (APC) residues were examined via a nine-time multiple leaching test. The effect of injected activated carbon in the APC residues on the PCDD/F leachability was also evaluated. When humic acid solution was used as a leachant, the leaching concentrations of PCDD/Fs fluctuated between the first and the fifth leaching, followed by a gradual increase and then suddenly reached maximum values at the leaching sequences around seventh and eighth. This significant enhancement in PCDD/F leachability was mainly due to an increase in the release of highly chlorinated PCDD/Fs. Leaching of PCDD/Fs with n-hexane was, in contrast, primarily caused by the partitioning of hydrophobic PCDD/Fs between the APC residue surface and the liquid phase of n-hexane. Consequently, the largest leaching concentrations for n-hexane tests achieved at the first leaching, followed by a decrease and reached plateaus. Solidification/stabilization (S/S) decreased the PCDD/F leachability up to the fifth leaching by the use of humic acid solution. However, S/S increased the PCDD/F leaching concentrations and rates with n-hexane. The activated carbon in APC residues significantly inhibited the release of PCDD/F with n-hexane. The inhibiting effect provided by activated carbon was, however, less significant by the use of humic acid solution. PMID:18028984

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

    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

  11. Influence of the Buchim copper leaching factory on the environ around the active Buchim copper mine

    Serafimovski, Todor; Nikolov, Nikolajco; Konzulov, Gerasim; Tasev, Goran; Sarafiloski, Sare

    2014-01-01

    Within this paper we are going to present a review of results for some particular contaminants such are: Co, Cu, Cd, Al, Fe, U etc., until the 2011 as well as review of results of monitoring (2012-2013) following the construction of the copper leaching facility. For the period covering period 1979-2011, in marked contrast, the water from the mine used to be acidic (pH 0.5 mg/L) 24 km downstream, where the River Madenska joins the River Bregalnica. Positive effects in regards to en...

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

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

    1990-01-01

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

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

    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.

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

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

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

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

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

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

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

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

    2015-06-01

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

  18. Stability and leaching of cobalt smelter fly ash

    Vítková, Martina; Hyks, Jiri; Ettler, Vojtěch;

    2013-01-01

    The leaching behaviour of fly ash from a Co smelter situated in the Zambian Copperbelt was studied as a function of pH (5–12) using the pH-static leaching test (CEN/TS 14997). Various experimental time intervals (48h and 168h) were evaluated. The leaching results were combined with the ORCHESTRA...... elements, the released concentrations were very similar after 48h and 168h, indicating near-equilibrium conditions in the system. Calcite, clinopyroxenes, quartz and amorphous phases predominated in the fly ash. Various metallic sulfides, alloys and the presence of Cu, Co and Zn in silicates and glass were...... release of Pb and Cu. However, there is a high risk of Co, Cu, Pb and Zn mobility in the acidic soils around the smelter facility. Therefore, potential local options for “stabilisation” of the fly ash were evaluated on the basis of the modelling results using the PHREEQC code....

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

    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.

  20. Leaching Properties of Naturally Occurring Heavy Metals from Soils

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

    2014-12-01

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

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

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

  2. Heavy Metals Leaching From Low Temperature Glazed Turkish Traditional Ceramic Wares

    HALEFOĞLU, Yusuf Ziya; EVLİYA, Hunay; KILINÇ, Nergis

    2013-01-01

    Ceramic pottery has long been recognized as a source of lead poisoning Lead copper chromium zinc and other heavy metals are found to leach from the glazes of some Turkish poorly fired glazed pottery in concentrations high enough to result serious health hazards Poorly fired ceramic ware with a lead based glaze can release lead to food in particular to acidic foods such as tomato sauce salsa Under acidic conditions leaching of level heavy metals is maximum Samples of ceramic ware were...

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

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

  4. Leaching of radionuclides from activated soil into groundwater

    Soil samples collected from the CERN site were irradiated by secondary radiation from the 400 GeV/c SPS proton beam at the H4IRRAD test area. Water samples were also irradiated at the same time. Detailed gamma spectrometry measurements and water scintillation analysis were performed to measure the radioactivity induced in the samples. FLUKA Monte Carlo simulations were performed to benchmark the induced radioactivity in the samples and to estimate the amount of tritium produced in the soil. Two leaching procedures were used and compared to quantify the radioactivity leached by water from the activated soil. The amount of tritium coming from both the soil moisture and the soil bulk was estimated. The present results are compared with literature data for the leaching of 3H and 22Na. - Highlights: • CERN soil and water samples were irradiated by secondary radiation from the 400 GeV/c proton beam. • Gamma spectrometry and liquid scintillation analysis were performed to determine the radioactivity induced in the samples. • FLUKA Monte Carlo simulations were performed to benchmark the induced radioactivity in the samples. • Two leaching procedures were used to quantify the amount of radioactivity leached out of the soil into the water. • Results are compared with literature data for the leaching of 3H and 22Na

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

    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.

  6. Leaching of heavy metals from steelmaking slags

    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

  7. The roasting and leaching of Witwatersrand pyrite concentrates

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

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

    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. PMID:23798147

  9. 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

    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.

  10. Influence of acidified acidity to uranium bioleaching

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

  11. Static leaching of uraniferous shales with countercurrent circuits

    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 H2SO4/I. We show the economy of the process. (Author)

  12. Hanford tank waste oxidative leach behavior analysis

    This paper study develops a modeling assumption for oxidative leaching Hanford tank wastes based on observed behavior of a limited set of samples tested. Oxidative Leaching of solids from Hanford tank wastes can reduce chromium concentrations appreciably

  13. Leaching of gold, silver and accompanying metals from circuit boards (PCBs) waste

    Jana Ficeriová; Peter Baláž; Eberhard Gock

    2011-01-01

    Au-Ag noble metal wastes represent a wide range of waste types and forms, with various accompanying metallic elements.The presented leaching strategy for Au-Ag contained in circuit boards (PCBs) aims at gaining gold and silver in the metallic form.Application of the proposed ammonium thiosulphate leaching process for the treatment of the above mentioned Au-Ag containing wastesrepresents a practical, economic and at the same time an ecological solution. The ammonium thiosulphate based leaching...

  14. Leaching assessments of toxic metals in waste plasma display panel glass

    M. Chen; Jiang, P.; Chen, H.; Ogunseitan, OA; Li, Y.

    2015-01-01

    © 2015 A&WMA. The plasma display panel (PDP) is rapidly becoming obsolete, contributing in large amounts to the electronic waste stream. In order to assess the potential for environmental pollution due to hazardous metals leached from PDP glass, standardized leaching procedures, chemical speciation assessments, and bioavailability tests were conducted. According to the Toxicity Characteristic Leaching Procedure (TCLP), arsenic in back glass was present at 4.46 ± 0.22 mg/L, close to its regula...

  15. Leaching of heavy metals and polycyclic aromatic hydrocarbons from reclaimed asphalt pavement

    Legret, M.; ODIE, L; DEMARE, D; Jullien, A.

    2005-01-01

    The work presented herein displays the results of a study addressing environmental concerns related to the possible leaching of pollutants from reclaimed asphalt pavement. Samples from an experimental site were tested in both static batch tests and column leaching tests. Selected heavy metals and polycyclic aromatic hydrocarbons (PAHs) were analysed in leachates. The results have allowed us to consider the leaching of pollutants to be rather weak for most of the parameters studied. Concentrat...

  16. Chemo-mechanical coupling behaviour of leached concrete. Part I : Experimental results

    NGUYEN,VH; COLINA, H; Torrenti, Jean Michel; Boulay, Claude; Nedjar, Boumediene

    2007-01-01

    This paper deals with concrete behaviour under chemical and mechanical degradations. Experimental investigations are described where the effects of the calcium leaching process of concrete on its mechanical properties are highlighted. The calcium leaching and mechanical tests on cement paste, mortar and concrete samples are presented. Because of the slow kinetics of leaching under deionised water, an accelerated method has been chosen by using an ammonium nitrate solution instead. The specime...

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

    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

  18. Kinetics of Leaching Process of Sella Uranium Ore Material, South Eastern Desert, Egypt

    The leaching of uranium from Sella uranium ore using hydrochloric acid solution has been studied. The effect of different parameters such as leaching time, hydrochloric acid concentration, liquid/ solid mass ion temperature, mechanical stirring speed are investigated in order to optimize various process for maximizing the recovery of uranium. The maximum percentage uranium leaching of 96 % 1 after 15 min of contact time leaching using 3.0 M hydrochloric acid and 4/1 liquid/ solid mass ratio at 26 °C with 400 rpm mechanical stirring speed. The experimental data are well interpreted with a shrinking core model with diffusion control through a porous product layer. By using the Arrhenius expression, the apparent activation energy for the uranium action is evaluated

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

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

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

    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.

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

    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. PMID:23334026

  2. Remediation of heavy metal polluted sediment by suspension and solid-bed leaching: estimate of metal removal efficiency.

    Löser, Christian; Zehnsdorf, Andreas; Hoffmann, Petra; Seidel, Heinz

    2007-01-01

    Remediation of heavy metal polluted sediment by extracting the metals with sulfuric acid can be performed as follows: abiotic suspension leaching, microbial suspension leaching, abiotic solid-bed leaching, and microbial solid-bed leaching. Abiotic leaching means that the acid is directly added, while microbial leaching means that the acid is generated from sulfur by microbes (bioleaching). These four principles were compared to each other with special emphasis on the effectiveness of metal solubilization and metal removal by subsequent washing. Abiotic suspension leaching was fastest, but suspending the solids exhibits some disadvantages (low solid content, costly reactors, permanent input of energy, high water consumption, special equipment required for solid separation, large amounts of waste water, sediment properties hinder reuse), which prevent suspension leaching in practice. Abiotic solid-bed leaching implies the supply of acid by percolating water which proceeds slowly due to a limited bed permeability. Microbial solid-bed leaching means the generation of acid within the bed and has been proven to be the only principle applicable to practice. Metal removal from leached sediment requires washing with water. Washing of solid beds was much more effective than washing of suspended sediment. The kinetics of metal removal from solid beds 0.3, 0.6 or 1.2m in height were similar; when using a percolation flow of 20lm(-2)h(-1), the removal of 98% of the mobile metals lasted 57-61h and required 8.5, 4.2 or 2.3lkg(-1) water. This means, the higher the solid bed, the lower the sediment-mass-specific demand for time and water. PMID:16908047

  3. Experiment and modeling for solvent leaching from paint matrix considering equilibrium

    The leaching behavior of remaining solvent from an epoxy paint coating when it is submerged in water was experimentally studied. A leach kinetics model considering the equilibrium of the solvent concentration in the paint matrix and in water was developed. Three model parameters, equilibrium constant K, leaching rate kd, and initial concentration of the solvent in the paint Cp0, were evaluated based on the experimental results, and empirical correlation equations for them were obtained. The model showed good qualitative and quantitative agreement with the observed evolution of the leached solvent mass in the present experiment. Also, the model showed consistency with experimental data in a different configuration. (author)

  4. SULPHUR DIOXIDE LEACHING OF URANIUM CONTAINING MATERIAL

    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.

  5. Solid waste and leaching studies using nuclear analytical techniques

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

  6. Study on leaching mechanism of sodium borosilicate glass microspheres

    Sodium borosilicate glasses find applications in heavy water plants, in nuclear waste immobilization, glass to metal sealing and various others fields. These glasses are found to be durable in corrosive ambient. Aim of the present work is to see the initial leaching mechanism/kinetics on sodium borosilicate glass microspheres. For this, glass with composition (mol%) 16.6Na2O-17.4 B2O3-66.0SiO2 was synthesized by melt-quench method. The studies were carried out at accelerated conditions of 120°C at different exposure hours, maximum upto 55 hrs in distilled water (DW). Studies on accelerated conditions helps in predicting long-term durability of the glass. The glass was taken in the form of micro spheres of 75 - 125 micron range. Glass microspheres were selected for the study as they have the advantage of maximum surface area. Their weight loss and surface study using SEM and SAXS were carried out intermittently. The weight loss observed was negligible even after 55 hrs of exposure at 120°C in DW. The interesting phenomenon of leaching were observed by SEM and SAXS studies. Initially few pore formation on the surface of spheres which grew in size and numerals followed by layer removal were observed by SAXS. On the removal of outer layer, inner exposed surface were leached in a similar pattern with pore formation. Initially only a few spheres were leached and gradually the intensity of leached spheres increased which was observed by SEM studies. The elemental analysis of the surface of leached and unleached spheres were carried out. The analysis showed the decrease in concentration of sodium on the leached layer. (author)

  7. Acid, basic, and neutral peptidases present different profiles in chromophobe renal cell carcinoma and in oncocytoma.

    Blanco, Lorena; Larrinaga, Gorka; Pérez, Itxaro; López, José I; Gil, Javier; Agirregoitia, Ekaitz; Varona, Adolfo

    2008-04-01

    Renal cell carcinomas (RCCs) are neoplasias with high prevalence and mortality. We previously reported that several peptidases may be involved in the pathophysiology of clear cell renal cell carcinoma (CCRCC). Now, to gain insight into the reasons that lead the various RCC types to behave very differently with regard to aggressiveness and response to anticancer treatments, we analyzed subsets of chromophobe renal cell carcinoma (ChRCC), and renal oncocytoma (RO), a benign tumor; as well as different grades and stages of CCRCCs. Particulate APN, APB, and APA activities were decreased in both ChRCC and RO (tumor vs. nontumor tissues). Interestingly, activities were downregulated in a tumor-type specific way and the intensities of the decreases were stronger in the benign tumor than in the malignant type. Moreover, when two key histopathological parameters for tumor prognosis (high vs. low stage and grade) were analyzed, increases of activity were also observed in several of these cell surface peptidases (APN, APB). Some soluble activities (APB, Asp-AP) were also downregulated in the RCCs. With respect to genetic expression, PSA and APN were in a positive correlation related to their activities in both ChRCC and RO; but not APB, Asp-AP, APA, and PGI. These results may suggest an involvement of several peptidases in the pathophysiology of renal cancer, since they presented different patterns of activity and expression in tumors with different behaviors. PMID:18216146

  8. Radiotracer investigation in gold leaching tanks

    Dagadu, C.P.K., E-mail: dagadukofi@yahoo.co.uk [Ghana Atomic Energy Commission, P.O. Box LG 80, Legon, Accra (Ghana); Akaho, E.H.K.; Danso, K.A. [Ghana Atomic Energy Commission, P.O. Box LG 80, Legon, Accra (Ghana); Stegowski, Z.; Furman, L. [Faculty of Physics and Applied Computer Science, AGH-UST, 30-059 Krakow (Poland)

    2012-01-15

    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. - Highlights: Black-Right-Pointing-Pointer I-131 radioactive tracer is suitable for tracing the aqueous phase in gold ore slurry. Black-Right-Pointing-Pointer Online data collection is more convenient method for tracer monitoring in industrial process systems. Black-Right-Pointing-Pointer The tanks-in-series model with exchange between active and stagnant zones is suitable to describe the flow behavior of leaching tanks. Black-Right-Pointing-Pointer The radiotracer RTD technique could be used to validate design data after process intensification in gold leaching tanks.

  9. Probable leaching mechanisms for spent fuel

    At the Pacific Northwest Laboratory, researchers in the Waste/Rock Interaction Technology Program are studying spent fuel as a possible waste form for the Office of Nuclear Waste Isolation. This paper presents probable leaching mechanisms for spent fuel and discusses current progress in identifying and understanding the leaching process. During the past year, experiments were begun to study the complex leaching mechanism of spent fuel. The initial work in this investigation was done with UO2, which provided the most information possible on the behavior of the spent-fuel matrix without encountering the very high radiation levels associated with spent fuel. Both single-crystal and polycrystalline UO2 samples were used for this study, and techniques applicable to remote experimentation in a hot cell are being developed. The effects of radiation are being studied in terms of radiolysis of water and surface activation of the UO2. Dissolution behavior and kinetics of UO2 were also investigated by electrochemical measurement techniques. These data will be correlated with those acquired when spent fuel is tested in a hot cell. Oxidation effects represent a major area of concern in evaluating the stability of spent fuel. Dissolution of UO2 is greatly increased in an oxidizing solution because the dissolution is then controlled by the formation of hexavalent uranium. In solutions containing very low oxygen levels (i.e., reducing solutions), oxidation-induced dissolution may be possible via a previously oxidized surface, through exposure to air during storage, or by local oxidants such as O2 and H2O2 produced from radiolysis of water and radiation-activated UO2 surfaces. The effects of oxidation not only increase the dissolution rate, but could lead to the disintegration of spent fuel into fine fragments

  10. Aluminium leaching from red mud by filamentous fungi.

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

    2015-11-01

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

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

    Sinha, Parikhit

    2015-11-01

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

  12. Uranium leaching from phosphate rock

    Uranium in phosphate rock was removed by means of alkaline leach solutions. Ammonium carbonate/bicarbonate solution produced a very stable uranyl carbonate compound which was separated by centrifugation. Radiometric analysis showed that about 40% of uranium was solubilized and it can be recuperated. This process could be used before the manufacture of phosphatic fertilizers and the final products would contain smaller uranium quantities. (author). 8 refs., 4 figs

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

    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.

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

    Rudeen, David Keith [GRAM, Inc., Albuquerque, NM; Weber, Paula D.; Lord, David L.

    2013-08-01

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

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

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

  16. Leaching modelling of slurry-phase carbonated steel slag.

    Costa, G; Polettini, A; Pomi, R; Stramazzo, A

    2016-01-25

    In the present work the influence of accelerated mineral carbonation on the leaching behaviour of basic oxygen furnace steel slag was investigated. The environmental behaviour of the material as evaluated through the release of major elements and toxic metals under varying pH conditions was the main focus of the study. Geochemical modelling of the eluates was used to derive a theoretical description of the underlying leaching phenomena for the carbonated material as compared to the original slag. Among the investigated elements, Ca and Si were most appreciably affected by carbonation. A very clear effect of carbonation on leaching was observed for silicate phases, and lower-Ca/Si-ratio minerals were found to control leaching in carbonated slag eluates as compared to the corresponding untreated slag sample as a result of Ca depletion from the residual slag particles. Clear evidence was also gained of solubility control for Ca, Mg and Mn by a number of carbonate minerals, indicating a significant involvement of the original slag constituents in the carbonation process. The release of toxic metals (Zn, V, Cr, Mo) was found to be variously affected by carbonation, owing to different mechanisms including pH changes, dissolution/precipitation of carbonates as well as sorption onto reactive mineral surfaces. The leaching test results were used to derive further considerations on the expected metal release levels on the basis of specific assumptions on the relevant pH domains for the untreated and carbonated slag. PMID:26489916

  17. Rates of leaching of radium from contaminated soils: an experimental investigation of radium bearing soils from Port Hope, Ontario

    The leachability of Ra-226 from soil at Port Hope, Ontario contaminated by waste from a long established U refinery is described here. A small-scale static leach test was devised to provide information to permit an assessment of hazard due to leaching in the environment. Two different leaching solutions were prepared to simulate a range of infiltrating water quality in disposal environments: one by bubbling CO2 into distilled water to pH 5.5, and another by bubbling SO2 into water to pH 3.5. Narrow-range size fractions of the soils (i.e. 0.250 to 0.105 mm) were leached for 30 to 45 days (equivalent rainfall of 2 to 3 yr). It was found that leaching is significantly affected by soil texture, total amounts leached and the maximum concentrations reached being much greater for coarser, and intermediate size fractions than for fine soil fractions. Also, leachant acidity significantly increased leaching rates and resulted in enhanced mobility in soils. A straight line for the plot of Q/Q0 (cumulative fraction released) vs. Tsup(1/2) (T is leaching time in days) indicated that leaching could be considered to be a diffusion phenomenon in accordance with Fick's law. Diffusion coefficients ranging from 5 X 10-11 to 2 X 10-13 cm2 day-1 were found. These coefficients provide a basis for estimating the fraction that would be leached over longer periods. (Auth.)

  18. Preparation of nuclear grade uranium oxide from Jaduguda leach liquor

    Studies have been conducted on pilot plant scale for solvent extraction of uranium from sulphuric acid leach liquor for Jaduguda uranium ore using Alamine-336 in kerosene as extractant and Isodecanol as modifier. A solvent extraction set up of 10 litre/min. capacity, having 4 stages each for extraction and stripping, was used. The uranium was recovered by stripping with 1M sodium chloride solution. The MDU precipitated from strip solution contained 85% U3O8. Since NFC has planned to set up its plant at Turamdih and a proposal was also made to integrate the process flow sheet of UCIL and NFC, it was decided to have a detailed studies on the production of nuclear grade uranium oxide from leach liquor. The work was done in line with the eluex process adopting one more stage of solvent extraction, i.e. after leaching in sulphuric acid and filtration, the clarified solution at pH of about 2 was processed through ion exchange system for extraction of uranium. The uranium was eluted with sulphuric acid. From the eluted solution uranium was again extracted with Alamine-336 in kerosene. Isodecanol was used as modifier. The stripping was done with ammonium nitrate-nitric acid, which is not a common practice. From the nitrate solution uranium was again extracted with TBP in kerosene and stripped with acidified water. From this strip solution ammonium diuranate was precipitated and ignited to uranium oxide. A parallel work was also conducted by extracting uranium directly from leach liquor by Alamine-336 and processing further as mentioned above. In both the cases, the uranium oxide produced contained the same percentage (99.8%) of U3O8. (author). 7 refs

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

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

    2011-01-01

    In this study, changes in physicochemical properties and leachability of indium from mechanically activated hard zinc residue by planetary mill were investigated. The results showed that mechanical activation increased specific surface area, reaction activity of hard zinc residue, and decreased its particle size, which had a positive effect on indium extraction from hard zinc residue in hydrochloric acid solution. Kinetics of indium leaching from unmilled and activated hard zinc residue...

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

    Gargul K.; Jarosz P.; Małecki S.

    2016-01-01

    Various types of waste materials containing zinc (e.g. dusts and sludges from gas dedusting process) are obtained in steel industry. The contents of Zn in these materials may vary considerably. Even a low concentration of zinc in recirculated products precludes their recycling in ferrous metallurgy aggregates. Long storage of this type of material can lead to contamination of soil and water by zinc compounds which can be leached out by acid rain, for example. This paper focuses on research in...