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Sample records for reducing acid leaching

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

    ZHEN Yulan; ZHANG Guohua; CHOU Kuochih

    2016-01-01

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

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

    Taysser Lasheen; S. A. Abu Elenein; W. A. Saleh; 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 ...

  3. Reducing Heavy Metal Element from Coal Bottom Ash by Using Citric Acid Leaching Treatment

    Yahya Ahmad Asyari

    2017-01-01

    Full Text Available Coal ash is the residue that is produced during coal combustion for instance fly ash, bottom ash or boiler slag which was primarily produced from the combustion of coal. With growth in coal burning power station, huge amount of coal bottom ash (CBA considered as hazardous material which are normally disposed in an on-site disposal system without any commercialization purpose. Previous researchers have studied the extraction of silica from agricultural wastes such as palm ash and rice husk ash (RHA and CBA by using leaching treatment method. In this study, the weaker acid, citric acid solution was used to replace the strong acid in leaching treatment process. Result showed that the heavy metal content such as Copper (Cu, Zinc (Zn and Lead (Pb can be decrease. Meanwhile the silica can be extracted up to 44% from coal bottom ash using citric acid leaching treatment under the optimum reaction time of 60 minutes with solution temperature of 60°C and concentration of citric acid more than 2%.

  4. Volume reducing and modifying of neutralized sludge from acid waste water treatment of uranium ore heap leaching

    Zhong Pingru; Ding Tongsen; Gu Jianghan

    1997-01-01

    A process is worked out on the basis of traditional lime neutralization, viz. acid waste water from uranium ore heap leaching is treated by limestone and lime double neutralizing-sludge recycling. First, the waste water is reacted with cheaper limestone to precipitate some metal ions, such as Fe and Al, which form hydroxides at lower pH, and neutralize strong acid, then neutralized with lime to required pH value. The formed precipitate as sludge is steadily recycled in the process. The principal advantage of the process over lime neutralization process is that reagent cost saved by 1/3 and formed sludge volume decreased by 2/3. Besides, the performances of sludge filtrating and settling are improved. The mechanism of sludge volume reducing and modification is also investigated

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

    Meng Yunsheng; Zheng Ying; Liu Hui; Cheng Hao; Zhou Lei; Liu Chao; Fan Baotuan; Li Jianhua

    2012-01-01

    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)

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

    Zhao, Shulan; Jia, Lina; Duo, Lian

    2016-05-01

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

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

    Jiang Lang

    2000-01-01

    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

  8. Urban trees reduce nutrient leaching to groundwater.

    Nidzgorski, Daniel A; Hobbie, Sarah E

    2016-07-01

    Many urban waterways suffer from excess nitrogen (N) and phosphorus (P), feeding algal blooms, which cause lower water clarity and oxygen levels, bad odor and taste, and the loss of desirable species. Nutrient movement from land to water is likely to be influenced by urban vegetation, but there are few empirical studies addressing this. In this study, we examined whether or not urban trees can reduce nutrient leaching to groundwater, an important nutrient export pathway that has received less attention than stormwater. We characterized leaching beneath 33 trees of 14 species, and seven open turfgrass areas, across three city parks in Saint Paul, Minnesota, USA. We installed lysimeters at 60 cm depth to collect soil water approximately biweekly from July 2011 through October 2013, except during winter and drought periods, measured dissolved organic carbon (C), N, and P in soil water, and modeled water fluxes using the BROOK90 hydrologic model. We also measured soil nutrient pools (bulk C and N, KCl-extractable inorganic N, Brays-P), tree tissue nutrient concentrations (C, N, and P of green leaves, leaf litter, and roots), and canopy size parameters (leaf biomass, leaf area index) to explore correlations with nutrient leaching. Trees had similar or lower N leaching than turfgrass in 2012 but higher N leaching in 2013; trees reduced P leaching compared with turfgrass in both 2012 and 2013, with lower leaching under deciduous than evergreen trees. Scaling up our measurements to an urban subwatershed of the Mississippi River (~17 400 ha, containing ~1.5 million trees), we estimated that trees reduced P leaching to groundwater by 533 kg in 2012 (0.031 kg/ha or 3.1 kg/km 2 ) and 1201 kg in 2013 (0.069 kg/ha or 6.9 kg/km 2 ). Removing these same amounts of P using stormwater infrastructure would cost $2.2 million and $5.0 million per year (2012 and 2013 removal amounts, respectively). © 2016 by the Ecological Society of America.

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

    Bosina, B.; Krepelka, J.; Urban, P.; Kropacek, J.; Stransky, J.

    1987-01-01

    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.)

  10. Reducing uranium and thorium level in Zircon: effect of heat treatment on rate of leaching

    Meor Yusoff Meor Sulaiman

    2002-01-01

    Considerable amount of uranium and thorium are found in Malaysian zircon and the level is much higher than the minimum value adopted by many importing countries. Selective leaching had been applied as an important technique to reduce these elements. An initial study was carried out using hydrochloric acid leaching system but the result was not favourable. The rate of uranium and thorium leached can be further improved by introducing a heat pretreatment process prior to leaching (Author)

  11. Acid agglomeration heap leaching: present status, principle and applications

    Zeng Yijun

    2004-01-01

    For extracting valuable metal from clay-bearing acidic ores of poor permeability, agglomerated acid heap leaching appears to be the most effective method, whereas conventional leaching and general heap leaching bring about unsatisfactory recovery and poor economic returns. The present state of research work on acid agglomeration worldwide and its basic principle are discussed. The first commercial application employing acid agglomeration-heap leaching in China is also introduced

  12. 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.

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

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

    2006-01-01

    There is increasing concern over P leaching from sandy soils applied with water-soluble P fertilizers. Laboratory column leaching experiments were conducted to evaluate P leaching from a typical acidic sandy soil in Florida amended with DPR fertilizers developed from dolomite phosphate rock (DPR) and N-Viro soil. Ten leaching events were carried out at an interval of 7 days, with a total leaching volume of 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

  14. Ultrasound augmented leaching of nickel sulfate in sulfuric acid and hydrogen peroxide media.

    Li, Haoyu; Li, Shiwei; Peng, Jinhui; Srinivasakannan, Chandrasekar; Zhang, Libo; Yin, Shaohua

    2018-01-01

    A new method of preparation high purity nickel sulfate assisted by ultrasonic was studied. The process mechanism was analyzed by Inductively Coupled Plasma (ICP), X-ray diffraction (XRD), Scanning electron microscopy (SEM), and Energy dispersive X-ray spectrometry (EDS).The reaction mechanisms of oxidizing leaching and ultrasonic leaching were explored, respectively. Results showed that ultrasonic treatment peel off the oxide film on the surface of nickel. The leachate under strongly agitated, the yield rate of nickel sulfate was accelerate. And the reaction area was increased by the cavitation effect, the liquid-solid reaction was promoted, and the activation energy was reduced. The leaching rate of nickel reached 46.29% by conventional leaching, which takes about 5h. Under the same conditions, the ultrasonic leaching rate reached 40%, only half of the conventional leaching time. Concentration of leaching agent, reaction temperature, ultrasonic power, leaching time had significant effect on the enhancement of the leaching reaction with ultrasonic radiation. The leaching rate of 60.41% under the optimum experiment conditions as follows: sulfuric acid concentration 30%, hydrogen peroxide 10%, leaching temperature 333K, ultrasonic power 200W and leaching time 4h. The kinetic study of the system was investigated, and the reaction rates of conventional leaching and ultrasonic leaching were controlled by diffusion, and the apparent activation energies were 16.2kJ/mol and 11.83kJ/mol. Copyright © 2017. Published by Elsevier B.V.

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

    Kosim-Affandi; Umar-Sarip; Alwi, Guswita; Sri-Sudaryanto

    2000-01-01

    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 p ine 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 H 2 SO 4 100 kg/ton, MnO 2 20 kg/ton, 50 % of solid with ore size - 65 mesh, temperature at 80 o C 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)

  16. Manual of acid in situ leach uranium mining technology

    2001-08-01

    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

  17. Manual of acid in situ leach uranium mining technology

    NONE

    2001-08-01

    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.

  18. Study on the utilization of a sodium-sulfuric acid solution for the uranium minerals' leaching

    Echenique, Patricia; Fruchtenicht, Fernando; Gil, Daniel; Vigo, Daniel; Bouza, Angel; Vert, Gabriela; Becquart, Elena

    1988-01-01

    Argentine uranium minerals have been leached at bench scale with a different agent trying to reduce sulfuric acid consumption. The leaching agent was a sodium sulfate-sulfuric acid solution and the ore was from Sierra Pintada (San Rafael - Mendoza). The work was performed in stirred vessel at atmospheric pressure. The influence of different variables, pH, temperature, oxidant agent, sodium sulfate concentration and time, in the sulfuric acid consumption and the uranium yield was studied. (Author) [es

  19. Laboratory study on leaching of a sandstone-type uranium deposit for acid in-situ leaching

    Wen Zhenqian; Yao Yixuan; Zheng Jianping; Jiang Yan; Cui Xin; Xing Yongguo; Hao Jinting; Tang Huazhang

    2013-01-01

    Ore samples were took from in-situ leaching experiment boreholes in a sandstone-type uranium deposit. Technological mineralogy study, agitating leaching and column leaching experiments were carried. The results show that the content of minerals consuming acid and deoxidized minerals is low. When sulfuric acid concentration was 1O g/L, initial uranium content was 0.0224%, and liquid-to-solid ratio was l.91, leaching rate of column leaching experiments is 89.19%, acid consumption is 8.2 kg/t ore, acid consumption is 41.88 t/tU. Acid leaching, technology is recommend for field in-situ leaching experiment, sulfuric acid concentration in confecting solution is 10 g/L, and oxidizing agent is needless during leaching process. (authors)

  20. Hydrochloric acid leach of Agnew Lake uranium concentrate

    Haque, K.E.; Ipekoglue, B.

    1981-10-01

    Hydrochloric acid leaching was conducted on the radioactive mineral concentrate separated from the Agenw Lake uranium ore. Leach tests conducted at the optimum conditions (75 0 C; 36 hours; 66.0 Kg HCl/tonne; solid:liquid -1:1) resulted in the extraction of 87% uranium and 84% radium. The radionuclide level of the residue was U-0.016%, Th-0.24% and Ra-65 pCi/g solids. However to obtain a residue almost free of radium (i.e., Ra level at the detection limit: 4-6 pCi/g solids), the first stage leach residue was further treated with hydrochloric acid. The radium level in the best second stage leach residue was also above the target level. Therefore, multistage (3 or 4) hydrochloric acid and/or neutral chloride leaching is recommended to obtain tailings almost free of radionuclide

  1. Leaching of Titanium and Silicon from Low-Grade Titanium Slag Using Hydrochloric Acid Leaching

    Zhao, Longsheng; Wang, Lina; Qi, Tao; Chen, Desheng; Zhao, Hongxin; Liu, Yahui; Wang, Weijing

    2018-05-01

    Acid-leaching behaviors of the titanium slag obtained by selective reduction of vanadium-bearing titanomagnetite concentrates were investigated. It was found that the optimal leaching of titanium and silicon were 0.7% and 1.5%, respectively. The titanium and silicon in the titanium slag were firstly dissolved in the acidic solution to form TiO2+ and silica sol, and then rapidly reprecipitated, forming hydrochloric acid (HCl) leach residue. Most of the silicon presented in the HCl leach residue as floccules-like silica gel, while most of the titanium was distributed in the nano-sized rod-like clusters with crystallite refinement and intracrystalline defects, and, as such, 94.3% of the silicon was leached from the HCl leach residue by alkaline desilication, and 96.5% of the titanium in the titanium-rich material with some rutile structure was then digested by the concentrated sulfuric acid. This provides an alternative route for the comprehensive utilization of titanium and silicon in titanium slag.

  2. Basic and acidic leaching of Melton Valley Storage Tank sludge at Oak Ridge National Laboratory

    Collins, J.L.; Egan, B.Z.; Beahm, E.C.

    1995-01-01

    Basic and acidic leaching tests were conducted with samples of sludge taken from an underground storage tank at the US Department of Energy Melton Valley Storage Tank facility at Oak Ridge National Laboratory. The tests evaluated separation technologies for use in sludge processing to concentrate the radionuclides and reduce the volumes of storage tank waste for final disposal. Study results of sludge characterization, caustic leaching of sludge samples at ambient temperature and at 95 degrees C, and acid leaching of sludge samples at ambient temperature are reported in detail

  3. A procedure for acid leaching of ores of the sandstone type, particularly of uranium ores

    Fiala, P.; Baloun, S.; Hinterholzinger, O.

    1990-01-01

    Ore mixed with the enriched fraction of the leached ore is leached with sulfuric acid at 5 to 220 degC. Bulky particles are sorted out from the mixture and reduced in size, and particles with a higher proportion of the useful component are separated from them. The latter particles constitute the enriched fraction of the leached ore, which is partially or completely returned to the mixture with the entering ore. The sorting should preferably be performed in an aqueous system. The assets of this procedure include a better homogenization of the mixture with the acid, a better stability of the reaction mixture which brings about reduced adhesion and solidification, and the possibility of extending the reaction time and increasing the temperature. The reduction in size makes for a better access of the leaching agent to the useful minerals, and the returning of the leachate to the reaction system spares sulfuric acid. (M.D.)

  4. Solvent extraction of uranium from high acid leach solution

    Ramadevi, G.; Sreenivas, T.; Navale, A.S.; Padmanabhan, N.P.H.

    2010-01-01

    A significant part of the total uranium reserves all over the world is contributed by refractory uranium minerals. The refractory oxides are highly stable and inert to attack by most of the commonly used acids under normal conditions of acid strength, pressure and temperature. Quantitative dissolution of uranium from such ores containing refractory uranium minerals requires drastic operating conditions during chemical leaching like high acid strength, elevated pressures and temperatures. The leach liquors produced under these conditions normally have high free acidity, which affects the downstream operations like ion exchange and solvent extraction

  5. Study of the sulfuric acid leaching and bacterial leaching of low grade uranium ore by orbital shaker experiment

    Li Guangyue; Liu Yulong; Wang Yongdong; Ding Dexin

    2009-01-01

    The sulphuric acid leaching and bacteria leaching by orbital shaker experiments were conducted for the low grade uranium ore from a uranium mine in Guangdong Province. The results show that, when the concentration of sulphuric acid and that of slurry were 30 g/L and 25%, respectively, the conditions were most favourable for sulphuric acid leaching and the rate of leaching reached 92.92%, that, when pH value was 1.5, inoculation amount, 10%, concentration of slurry, 10%, the conditions were most favourable for bacteria leaching and the rate of leaching reached 95.93%, that, compared with sulphuric acid leaching, bacteria leaching decreased sulphuric acid consumption by 17.2% and increased the rate of leaching by 3%, and that, under the most favourable conditions for suphuric acid leaching, if 1% natrium chlorate was added, the rate of leaching increased to 96.46%, but 10 kg of natrium chlorate was consumed for 1 ton of uranium ore. (authors)

  6. Leaching of sodium carbonate cakes by nitric acid

    Troyanker, L.S.; Nikonov, V.N.

    1977-01-01

    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%

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

    Gee, G.W.; Begej, C.W.; Campbell, A.C.; Sauter, N.N.; Opitz, B.E.; Sherwood, D.R.

    1981-01-01

    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. Acid leaching of natural chrysotile asbestos to mesoporous silica fibers

    Maletaškić, Jelena; Stanković, Nadežda; Daneu, Nina; Babić, Biljana; Stoiljković, Milovan; Yoshida, Katsumi; Matović, Branko

    2018-04-01

    Nanofibrous silica with a high surface area was produced from chrysotile by the acid-leaching method. Natural mineral chrysotile asbestos from Stragari, Korlace in Serbia was used as the starting material. The fibers were modified by chemical treatment with 1 M HCl and the mineral dissolution was monitored by transmission electron microscopy, X-ray powder diffraction, inductively coupled plasma spectrometry and low-temperature nitrogen adsorption techniques to highlight the effects of the leaching process. The results showed that the applied concentration of acid solution and processing time of 4 h were sufficient to effectively remove the magnesium hydroxide layer and transform the crystal structure of the hazardous starting chrysotile to porous SiO2 nanofibers. With prolonged acid leaching, the specific surface area, S BET, calculated by BET equation, was increased from 147 up to 435 m2 g- 1, with micropores representing a significant part of the specific surface.

  9. Characterization of dross and its recovery by sulphuric acid leaching

    Rahmani, S. A.; Meidianto, A.; Amal, M. I.; Wismogroho, A. S.; Widayatno, W. B.

    2018-03-01

    This paper reports the characterization of dross from galvanizing process and its recovery using acidic leaching method. The diffraction profile of dross showed identical peaks with that of ZnO. The X-ray Fluorescence (XRF) analysis identified the content of following metals: Zn, Fe, Mn, Ga, Co, and W. The thermal behaviour examination revealed the existence of some volatiles within the initial sample. The acidic leaching at various concentrations of sulphuric acid was conducted to determine the optimum concentration for zinc recovery and the highest yield of zinc sulphate. It is concluded that the optimum concentration of H2SO4 for this kind of dross is 4 M with 71.9% yield of ZnSO4. The result of leaching process was confirmed by infrared spectrum, where various absorptions corresponding to SO4 2- and Zn-O bands were observed.

  10. Acid pre-treatment method for in situ ore leaching

    Mallon, R.G.; Braun, R.L.

    1975-01-01

    An acid leaching method is described for the recovery of a desired element from a subterranean rubblized body of primary ore containing the element and also having associated therewith a carbonate mineral wherein the rubblized ore body is flooded with an aqueous acidic solution in order to release carbon dioxide from the associated carbonate mineral. After a substantial portion of the available carbon dioxide is released and removed from the ore body, as by venting to the atmosphere, an oxidizing gas is introduced into the flooded, rubblized ore to oxidize the ore and form an acid leach solution effective in the presence of the dissolved oxidizing gas to dissolve the ore and cause the desired element to go into solution. The leach solution is then circulated to the surface where the metal values are recovered therefrom

  11. A kinetics study of acetic acid on cobalt leaching of spent LIBs: Shrinking Core Model

    Setiawan Hendrik

    2018-01-01

    Full Text Available Lithium-ion batteries (LIBs are secondary rechargeable power sources which increasing production also leads to large amount of waste. In order to environmentally friendly reduce the waste, this work aimed to use acetic acid as a substitute leaching agent to leach Co metals which constitutes about 72.39% wt of the battery cathode. The leaching process was done in a three-necked-flask where calcined LIB cathode powder was mixed with acetic acid solution. The variables of the leaching process under investigation were solution pH, concentration of H2O2 in the solution, S/L ratio, temperature and reaction time. Experimental results showed that only temperature significantly influenced the leaching rate of Co. Since the process was exothermic, the maximum recovery decreased as temperature increased. Conventional shrinking core model that considers diffusion and irreversible surface reaction resistances was found not sufficient to predict the kinetics of the Co leaching with acetic acid. A more representative kinetics model that considers a reversible reaction of Co complex formation needs to be further developed.

  12. 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.

  13. Acid leaching of mixed spent Li-ion batteries

    A.A. Nayl

    2017-05-01

    Full Text Available Acid leaching for different types of mixed spent Li-ion mobile batteries is carried out after alkali decomposition using NH4OH followed by H2SO4 + H2O2 leaching. In the alkali decomposition step, the effects of reaction time, NH4OH concentration, liquid/solid mass ratio and reaction temperature on the decomposition process are investigated to remove Al, Cu, Mn, Ni, Co, and Li. After alkaline treatment, the alkali paste is treated to leach the remaining metals using H2SO4 + H2O2. The significant effects of reaction time, acid concentration, H2O2 concentration, liquid/solid mass ratios and reaction temperature on the leaching rate are studied. More than 97% of Al, Mn, Ni, Co, and Li and about 65% Cu are leached in two stages. Kinetic analysis shows that, the data fit with chemical reaction control mechanism and the activation energies for the investigated metals using the Arrhenius equation ranged from 30.1 to 41.4 kJ/mol. Recovered metals are precipitated from the leaching liquor at varying pH values using NaOH solution and Na2CO3. Firstly, Mn is precipitated as MnCO3 at pH = 7.5. Secondly, at pH = 9.0, nickel is precipitated as NiCO3. Thirdly, as the pH of the leaching liquor reaches 11–12, Co(OH2 is precipitated and the remaining Li is readily precipitated as Li2CO3 using a saturated Na2CO3 solution. Based on the experimental data, a flow sheet is developed and tested for the recovery process.

  14. LEACH ARCILLAS ACTIVATED PARTIAL ACID SULFURICO

    Romero Y Otiniano, P.; Pizarra Cabrera, R.

    2014-01-01

    This work is concerned with the activation of calcium bentonite from Junín- Perú (with a moisture content of 24.1% and an average of particle size 40 µ ) with sulphuric acid. The parameters studied are the ratio of bentonite to acid solution, acid concentration and reaction time to boiling temperatura of the mixture. The optimum conditions obtained are the following: 0.47 kg. of bentonite/kg. of acid solution to 4.8 N, 4 h of treatment to 104 ºC and the conversion of 45.6% alumina and 73.5% o...

  15. Selection of organic acid leaching reagent for recovery of zinc and manganese from zinc-carbon and alkaline spent batteries

    Yuliusman; Amiliana, R. A.; Wulandari, P. T.; Ramadhan, I. T.; Kusumadewi, F. A.

    2018-03-01

    Zinc-carbon and alkaline batteries are often used in electronic equipment that requires small quantities of power. The waste from these batteries contains valuable metals, such as zinc and manganese, that are needed in many industries and can pollute the environment if not treated properly. This paper concerns the recovery of zinc and manganese metals from zinc-carbon and alkaline spent batteries with leaching method and using organic acid as the environmental friendly leaching reagent. Three different organic acids, namely citric acid, malic acid and aspartic acid, were used as leaching reagents and compared with sulfuric acid as non-organic acid reagents that often used for leaching. The presence of hydrogen peroxide as manganese reducers was investigated for both organic and non-organic leaching reagents. The result showed that citric acid can recover 64.37% Zinc and 51.32% Manganese, while malic acid and aspartic acid could recover less than these. Hydrogen peroxide gave the significant effect for leaching manganese with non-organic acid, but not with organic acid.

  16. Counter-current acid leaching process for copper azole treated wood waste.

    Janin, Amélie; Riche, Pauline; Blais, Jean-François; Mercier, Guy; Cooper, Paul; Morris, Paul

    2012-09-01

    This study explores the performance of a counter-current leaching process (CCLP) for copper extraction from copper azole treated wood waste for recycling of wood and copper. The leaching process uses three acid leaching steps with 0.1 M H2SO4 at 75degrees C and 15% slurry density followed by three rinses with water. Copper is recovered from the leachate using electrodeposition at 5 amperes (A) for 75 min. Ten counter-current remediation cycles were completed achieving > or = 94% copper extraction from the wood during the 10 cycles; 80-90% of the copper was recovered from the extract solution by electrodeposition. The counter-current leaching process reduced acid consumption by 86% and effluent discharge volume was 12 times lower compared with the same process without use of counter-current leaching. However, the reuse of leachates from one leaching step to another released dissolved organic carbon and caused its build-up in the early cycles.

  17. Leaching of basic oxygen furnace sludge with sulphuric acid

    Andrea Miškufová

    2010-03-01

    Full Text Available In this study the hydrometallurgical processing of BOF sludge in the sulphuric acid solutions under atmospheric pressureand temperatures up to 100 °C is investigated on a laboratory scale. The influence of sulphuric acid concentration, temperature, timeand liquid to solid ratio (L:S on the leaching process was studied. The main aim of this study was to determine optimal conditions whenthe maximum amount of zinc passes into the solution.

  18. Gangue minerals reactivity in oxidative leaching of uraninite with dilute sulfuric acid from low-grade ores. An approach for better leach liquor purity

    Madakkaruppan, V.; Chanchal Sarbajna; Pius, Anitha; Sreenivas, T.

    2016-01-01

    This paper presents results of sulfuric acid leaching studies carried out on a low-grade uranium ore with emphasis on attaining maximum uranium leachability with minimum content of detrimental ions like Si, Al, Fe, Mg and P, which originate from reactive gangue minerals like chlorite, biotite and apatite. A 'two-stage leaching' scheme was developed wherein the total reaction time and the pH of the slurry were split such that the initial phase consists of higher acidity with shorter reaction period and the later phase involves reduced acidity and longer reaction time. This modification gives leach liquor of higher purity with good uranium leachability at relatively lower acid consumption. (author)

  19. Basic and Acidic Leaching of Sludge from Melton Valley Storage Tank W-25

    Collins, J.L., Egan, B.Z., Beahm, E.C., Chase, C.W., Anderson, K.K.

    1997-10-01

    Bench-scale leaching tests were conducted with samples of tank waste sludge from the Melton Valley Storage Tank (MVST) Facility at Oak Ridge National Laboratory (ORNL) to evaluate separation technology processes for use in concentrating the radionuclides and reducing the volume of waste for final disposal. This paper discusses the hot cell apparatus, the characterization of the sludge, the leaching methodology, and the results obtained from a variety of basic and acidic leaching tests of samples of sludge at ambient temperature. Basic leaching tests were also conducted at 75 and 95 deg C. The major alpha-,gamma., and beta-emitting radionuclides in the centrifuged, wet sludge solids were {sup 137}Cs, {sup 60}Co, {sup 154}Eu, {sup 241}Am, {sup 244}Cm {sup 90}Sr, Pu, U, and Th. The other major metals (in addition to the U and Th) and anions were Na, Ca, Al, K, Mg, NO{sub 3}{sup -},CO{sub 3}{sup 2-}, OH{sup -}, and O{sup 2-} organic carbon content was 3.0 +/- 1.0%. The pH was 13. A surprising result was that about 93% of the {sup 137}Cs in the centrifuged, wet sludge solids was bound in the solids and could not be solubilized by basic leaching at ambient temperature and 75 deg C. However, the solubility of the {sup 137}Cs was enhanced by heating the sludge to 95 deg C. In one of the tests,about 42% of the {sup 137}Cs was removed by leaching with 6.3 M NaOH at 95 deg C.Removing {sup 137}Cs from the W-25 sludge with nitric acid was a slow process. About 13% of the {sup 137}Cs was removed in 16 h with 3.0 M HNO{sub 3}. Only 22% of the {sup 137}Cs was removed in 117 h usi 6.0 M HNO{sub 3}. Successive leaching of sludge solids with 0.5 M, 3.0 M, 3.0 M; and 6.0 M HNO{sub 3} for a total mixing time of 558 h removed 84% of the {sup 137}Cs. The use of caustic leaching prior to HNO{sub 3} leaching, and the use of HF with HNO{sub 3} in acidic leaching, increased the rate of {sup 137}Cs dissolution. Gel formation proved to be one of the biggest problems associated with HNO{sub 3

  20. Basic and Acidic Leaching of Sludge from Melton Valley Storage Tank W-25

    Collins, J.L.; Egan, B.Z.; Beahm, E.C.; Chase, C.W.; Anderson, K.K.

    1997-10-01

    Bench-scale leaching tests were conducted with samples of tank waste sludge from the Melton Valley Storage Tank (MVST) Facility at Oak Ridge National Laboratory (ORNL) to evaluate separation technology processes for use in concentrating the radionuclides and reducing the volume of waste for final disposal. This paper discusses the hot cell apparatus, the characterization of the sludge, the leaching methodology, and the results obtained from a variety of basic and acidic leaching tests of samples of sludge at ambient temperature. Basic leaching tests were also conducted at 75 and 95 deg C. The major alpha-,gamma., and beta-emitting radionuclides in the centrifuged, wet sludge solids were 137 Cs, 60 Co, 154 Eu, 241 Am, 244 Cm 90 Sr, Pu, U, and Th. The other major metals (in addition to the U and Th) and anions were Na, Ca, Al, K, Mg, NO 3 - ,CO 3 2- , OH - , and O 2- organic carbon content was 3.0 +/- 1.0%. The pH was 13. A surprising result was that about 93% of the 137 Cs in the centrifuged, wet sludge solids was bound in the solids and could not be solubilized by basic leaching at ambient temperature and 75 deg C. However, the solubility of the 137 Cs was enhanced by heating the sludge to 95 deg C. In one of the tests,about 42% of the 137 Cs was removed by leaching with 6.3 M NaOH at 95 deg C.Removing 137 Cs from the W-25 sludge with nitric acid was a slow process. About 13% of the 137 Cs was removed in 16 h with 3.0 M HNO 3 . Only 22% of the 137 Cs was removed in 117 h usi 6.0 M HNO 3 . Successive leaching of sludge solids with 0.5 M, 3.0 M, 3.0 M; and 6.0 M HNO 3 for a total mixing time of 558 h removed 84% of the 137 Cs. The use of caustic leaching prior to HNO 3 leaching, and the use of HF with HNO 3 in acidic leaching, increased the rate of 137 Cs dissolution. Gel formation proved to be one of the biggest problems associated with HNO 3 leaching of the W-25 sludge

  1. Vanadium Extraction from Shale via Sulfuric Acid Baking and Leaching

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

    2018-01-01

    Fluorides are widely used to improve vanadium extraction from shale in China. Sulfuric acid baking-leaching (SABL) was investigated as a means of recovering vanadium which does not require the use of fluorides and avoids the productions of harmful fluoride-containing wastewater. Various effective factors were systematically studied and the experimental results showed that 90.1% vanadium could be leached from the shale. On the basis of phase transformations and structural changes after baking the shale, a mechanism of vanadium extraction from shale via SABL was proposed. The mechanism can be described as: (1) sulfuric acid diffusion into particles; (2) the formation of concentrated sulfuric acid media in the particles after water evaporation; (3) hydroxyl groups in the muscovite were removed and transient state [SO4 2-] was generated; and (4) the metals in the muscovite were sulfated by active [SO4 2-] and the vanadium was released. Thermodynamics modeling confirmed this mechanism.

  2. Resistance evaluation expanded perlite the leaching acid: variation of parameters concentration, time and leaching agent

    Almeida, J.M.F. de; Damasceno Junior, E.; Oliveira, E.S.; Fernandes, N.S.

    2016-01-01

    The expanded perlite is an amorphous aluminosilicate which presents in its composition about 75.0% silicon oxide (SiO2), also having other species in the composition as oxides of some metals. Silicas and silicates have been used in the environmental field, in relevant anti-corrosive activity. In this context, materials that exposes too many highly acidic media, require preservation against this type of wear, as this type of damage causes a great financial loss, thereby requiring low-cost, abundant materials, non-toxic and easy to purchase as some silica coating. The study evaluated the perlite expanded resistance against an acid leaching process. With undeniability the use of strong acids and different working conditions were not able to remove the oxides present on the expanded perlite sample, thus demonstrating the high strength of the expanded perlite against acid attacks. (author)

  3. Acid leaching of coal: to produce clean fuels from Turkish lignite

    Seferinoglu, Meryem [Mineral Research and Exploration Directorate (Turkey)], email: meryem_seferinoglu66@yahoo.com; Duzenli, Derya [Ankara Central Laboratory (Turkey)

    2011-07-01

    With the increasing concerns about the environment, energy producers and governments are looking at developing clean energy sources. However, Turkey has limited clean energy resources and is using low grade coal which has high sulphur content as an alternative energy source. The aim of this paper is to study the possibility of generating clean fuel from Edirne Lignite and to get a better understanding of chemical mechanisms involved in coal leaching with hydrofluoric acid (HF) solutions. Leaching was conducted on Edirne Lignite with HF solution at ambient temperature and the effects of parameters such as reaction time and concentration of acid solutions on the process were evaluated. The optimum conditions were found and it was shown that ash levels can be reduced from 28.9% to 10.5% and the calorific value increased by 500kcal/kg with the HF leaching method. This study demonstrated that the production of clean fuel from high sulphur lignite is possible.

  4. Selective removal of chromium from sulphuric acid leach liquor of ...

    ... removed in multiple batch extractions from the leach liquor and titanium losses were minimal (< 1%). The chromium content of extracted solutions was reduced to less than 1 ppm and thermal hydrolysis of these solutions yielded white titanium(IV) oxide pigments that are suitable for use in the coatings pigment industry.

  5. Reduction of water consumption in the dynamic acid leaching process of uranium

    Chocron, M.; Arias, M.J.; Avato, A.M.; Díaz, V.A.

    2013-01-01

    In 2006 the Argentine state announced a plan to reactivate the nuclear sector. As a result of this decision, the National Atomic Energy Commission (CNEA) resumed its research in uranium mining for Argentine deposits. The first step was the study of the leaching process, mainly the dynamic leaching. In this work the influence of the reduction of the water content in the dynamic leaching process in acid medium, at laboratory scale and under batch operating conditions, on the main operating parameters (concentration of the leaching reagent, the oxidizing reagent and The reaction temperature). The percentages of pulp solids studied in the dynamic leaching were 53% and 66% w / w. For the tests uranium-molybdenum ores of the sandstone type were used. Two different working schemes were used to study the different operating parameters. In the tests carried out with 53% of solid in pulp, the parameters were studied individually (varying one parameter at a time), while working with a pulp of 66% solids, the study of the parameters was performed by a Factorial design of two levels of three variables, which in addition to studying the dependence of the different parameters allowed to analyze how they influence each other. During the leaching tests with 66% solids content in pulp, changes in the geometric and dynamic conditions of the system were necessary because of the poor mixing observed when using the same agitation conditions used in the leaching tests with 53% solids in pulp. When comparing the tests for both solids content conditions (53% and 66% w / w), similar extraction yields were observed for both uranium and molybdenum (more than 90% for uranium and more than 80% for The molybdenum). As a final result, the process water consumption (380 liters of water per ton of ore) is reduced by more than 50% by working with pulps of 66% w / w of solids, obtaining acceptable extraction yields and, as an additional, reducing The consumption of the leaching reagent. (author)

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

    Yong-dong Wang; Guang-yue Li; De-xin Ding; Zhi-xiang Zhou; Qin-wen Deng; Nan Hu; Yan Tan

    2013-01-01

    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)

  7. 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.

  8. Comparative studies on acid leaching of zinc waste materials

    Rudnik, Ewa; Włoch, Grzegorz; Szatan, Leszek

    2017-11-01

    Three industrial waste materials were characterized in terms of their elemental and phase compositions, leaching behaviour in 10% sulfuric acid solution as well as leaching thermal effects. Slag from melting of mixed metallic scrap contained about 50% Zn and 10% Pb. It consisted mainly of various oxides and oxy-chlorides of metals. Zinc spray metallizing dust contained about 77% Zn in form of zinc and/or zinc-iron oxides, zinc metal and Zn-Fe intermetallic. Zinc ash from hot dip galvanizing was a mixture of zinc oxide, metallic zinc and zinc hydroxide chloride and contained about 80% Zn. Dissolution efficiency of zinc from the first material was 80% (independently on the solid to liquid ratio, 50-150 kg/m3), while decrease of the efficacy from 80% to 60% with increased solid to liquid ratio for the two remaining materials was observed. Both increase in the temperature (20 °C to 35 °C) and agitation rate (300 rpm to 900 rpm) did not improve seriously the leaching results. In all cases, transfer of zinc ions to the leachate was accompanied by different levels of solution contamination, depending on the type of the waste. Leaching of the materials was exothermic with the similar reaction heats for two high oxide-type products (slag, zinc ash) and higher values for the spray metallizing dust.

  9. Technical application of agglomerated acidic heap leaching of clay-bearing uranium ore in China

    Zeng Yijun; Li Jianhua; Li Tieqiu; Zhong Pingru

    2002-01-01

    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 is difficult to acidic heap leaching. The Research Institute of Uranium Mining has engaged several years studies on the cementing agents of acidic agglomeration, agglomeration conditions, as well as the curing measures of agglomerated balls. On the basis of these studies, several types of clay-bearing ores have been tested with good results. The technique of agglomerated acidic heap leaching has been successfully applied in a uranium mine. Since agglomeration has effectively increased the permeability of ore heap, its leaching period is decreased from 200 days to 60 days, the leaching efficiency is increased to 96% from less than 40% comparing with direct heap leaching program

  10. British strong-acid leach process targeted at refractory uranium ores

    Anon.

    1975-01-01

    The UKAEA-patented strong-acid leach process for refractory U ores is briefly outlined with emphasis on its variations from the conventional dilute-acid process and the projected economics for a processing plant using this process. The process uses 6N H 2 SO 4 with a sharply reduced leaching time over conventional processes. The solubilized U is removed by percolation and the use of only about 10 percent liquid produces less effluent. Conventional processing plant equipment can be used except at the feed preparation, acid mixing, curing, and washing stages. Ore can be processed at larger grain sizes and the milling is done in a dry rod mill. Alternatives to the percolation removal of U are listed. Other work being done by UKAEA on U recovery from ores is briefly indicated. (U.S.)

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

    Van Tonder, D.; Kotze, M.

    2007-01-01

    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 U 3 O8 over a solution concentration range of 40 to 1500 mg/L U 3 O8. 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

  12. Physical and chemical mechanism underlying ultrasonically enhanced hydrochloric acid leaching of non-oxidative roasting of bastnaesite.

    Zhang, Dongliang; Li, Mei; Gao, Kai; Li, Jianfei; Yan, Yujun; Liu, Xingyu

    2017-11-01

    In this study, we investigated an alternative to the conventional hydrochloric acid leaching of roasted bastnaesite. The studies suggested that the rare earth oxyfluorides in non-oxidatively roasted bastnaesite can be selectively leached only at elevated temperatures Further, the Ce(IV) in oxidatively roasted bastnaesite does not leach readily at low temperatures, and it is difficult to induce it to form a complex with F - ions in order to increase the leaching efficiency. Moreover, it is inevitably reduced to Ce(III) at elevated temperatures. Thus, the ultrasonically-assisted hydrochloric acid leaching of non-oxidatively roasted bastnaesite was studied in detail, including, the effects of several process factors and the, physical and chemical mechanisms underlying the leaching process. The results show that the leaching rate for the ultrasonically assisted process at 55°C (65% rare earth oxides) is almost the same as that for the conventional leaching process at 85°C. Based on the obtained results, it is concluded that ultrasonic cavitation plays a key role in the proposed process, resulting not only in a high shear stress, which damages the solid surface, but also in the formation of hydroxyl radicals (OH) and hydrogen peroxide (H 2 O 2 ). Standard electrode potential analysis and experimental results indicate that Ce(III) isoxidized by the hydroxyl radicals to Ce(IV), which can be leached with F - ions in the form of a complex, and that the Ce(IV) can subsequently be reduced to Ce(III) by the H 2 O 2. This prevents the Cl - ions in the solution from being oxidized to form chlorine. These results imply that the ultrasonically-assisted process can be used for the leaching of non-oxidatively roasted bastnaesite at low temperatures in the absence of a reductant. Copyright © 2017 Elsevier B.V. All rights reserved.

  13. EFFECTS OF MINERAL ADMIXTURE ON THE CARBONIC ACID LEACHING RESISTANCE OF CEMENT-BASED MATERIALS

    Yun Dong

    2017-07-01

    Full Text Available In order to reveal the degradation process and deterioration mechanism of cement-based materials, this paper analyzes the effects of carbonic acid leaching on the mechanical strength of mortars, as well as relative mass loss, microstructure, and composition of various cement pastes. The results indicate that cement pastes containing less than 20 % fly ash have higher carbonic acid leaching resistance than cement pastes without fly ash. However, after carbonic acid leaching, the compressive strength of the samples with fly ash is lower than that of the cement pastes without fly ash. The leaching resistance is good for samples cured at an early age before leaching. Carbonic acid leaching proceeds from the paste surface to the interior. The incorporation of an appropriate amount of slag powder helps to increase the density of the paste. Due to the pozzolanic activity of fly ash at late-stage leaching, a mixture of fly ash (≤ 20 % and slag powder (≤ 20 % effectively improves carbonic acid leaching resistance. The products of early-stage leaching were mainly CaCO₃ and small amounts of SiO₂ and Fe₂O₃. The C-S-H phase at the paste surface suffered serious damage after long periods of leaching, and the main products of leaching were SiO₂ and Fe₂O₃.

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

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

    2015-07-01

    Waste printed circuit boards (WPCBs) are attracting increasing concerns because the recovery of its content of valuable metallic resources is hampered by the presence of hazardous substances. In this study, we used ionic liquids (IL) to leach copper from WPCBs. [BSO3HPy]OTf, [BSO3HMIm]OTf, [BSO4HPy]HSO4, [BSO4HMim]HSO4 and [MIm]HSO4 were selected. Factors that affect copper leaching rate were investigated in detail and their leaching kinetics were also examined with the comparison of [Bmim]HSO4. The results showed that all six IL acids could successfully leach copper out, with near 100% recovery. WPCB particle size and leaching time had similar influences on copper leaching performance, while IL acid concentration, hydrogen peroxide addition, solid to liquid ratio, temperature, showed different influences. Moreover, IL acid with HSO4(-) was more efficient than IL acid with CF3SO3(-). These six IL acids indicate a similar behavior with common inorganic acids, except temperature since copper leaching rate of some IL acids decreases with its increase. The results of leaching kinetics studies showed that diffusion plays a more important role than surface reaction, whereas copper leaching by inorganic acids is usually controlled by surface reaction. This innovation provides a new option for recovering valuable materials such as copper from WPCBs. Copyright © 2015 Elsevier Ltd. All rights reserved.

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

    Jean-Soro, Liliane; Bordas, François; Bollinger, Jean-Claude

    2012-01-01

    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.

  16. 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

  17. Process Design Aspects for Scandium-Selective Leaching of Bauxite Residue with Sulfuric Acid

    Konstantinos Hatzilyberis; Theopisti Lymperopoulou; Lamprini-Areti Tsakanika; Klaus-Michael Ochsenkühn; Paraskevas Georgiou; Nikolaos Defteraios; Fotios Tsopelas; Maria Ochsenkühn-Petropoulou

    2018-01-01

    Aiming at the industrial scale development of a Scandium (Sc)-selective leaching process of Bauxite Residue (BR), a set of process design aspects has been investigated. The interpretation of experimental data for Sc leaching yield, with sulfuric acid as the leaching solvent, has shown significant impact from acid feed concentration, mixing time, liquid to solids ratio (L/S), and number of cycles of leachate re-usage onto fresh BR. The thin film diffusion model, as the fundamental theory for l...

  18. Acid pressure leaching of a concentrate containing uranium, thorium and rare earth elements

    Lan Xinghua; Peng Ruqing.

    1987-01-01

    The acid pressure leaching of a concentrate containing rinkolite for recovering uranium, thorium and rare earth elements is described. The laboratory and the pilot plant test results are given. Under the optimum leaching conditions, the recovery of uranium, thorium and rare earth elements are 82.9%, 86.0% and 88.3% respectively. These results show that the acid pressure leaching process is a effective process for treating the concentrate

  19. Leaching and recovery of zinc and copper from brass slag by sulfuric acid

    Ahmed, I.M.; Nayl, A.A.; Daoud, J.A.

    2016-01-01

    Leaching and recovery processes for zinc and copper from brass slag by sulfuric acid were carried out and iron and aluminum were also precipitated as hydroxides in addition to silica gel. The factors affecting the performance and efficiency of the leaching processsuch as agitation rate, leaching time, acid concentration and temperature were separately investigated. The results obtained revealed that zinc and copper are successfully recovered from these secondary resources, where the percent r...

  20. Investigation of copper(I sulphide leaching in oxidative hydrochloric acid solution

    Branislav Marković

    2015-12-01

    Full Text Available Present work is focused on the copper (I sulphide leaching with sodium chloride in hydrochloric acid solution and with introduction of gaseous oxygen. Chemical reactions of leaching and their thermodynamic probabilities are predicted based on the literature data and products which were formed during the process and the overall leaching reaction was defined. The influence of temperature and time on the leaching degree of copper was experimentally determined. The quantity of dissolved copper increases with the increase of both investigated parameters. Elemental sulphur was formed as the main leaching product, precipitated at the particle surfaces and chloride ions have a role to disrupt the creation of this passive layer.

  1. Leaching behavior of lanthanum, nickel and iron from spent catalyst using inorganic acids

    Astuti, W.; Prilitasari, N. M.; Iskandar, Y.; Bratakusuma, D.; Petrus, H. T. B. M.

    2018-01-01

    Highly technological applications of rare earth metals (REs) and scarcity of supply have become an incentive torecover the REs from various resources, which include high grade and low grade ores, as well as recycledwaste materials. Spent hydrocracking catalyst contain lanthanum and a variety of valuable metals such as nickel and iron. This study investigated the recovery of lanthanum, nickel and iron from spent hydrocracking catalyst by leaching using various inorganic acid (sulfuric acid, hydrochloric acid, and nitric acid). The effect of acid concentration, type of acid and leaching temperature was conducted to study the leaching behavior of each valuable metal from spent-catalyst. It has been shown that it is possible to recover more than 90% of lanthanum, however the leaching efficiency of nickel and iron in this process was very low. It can be concluded that the leaching process is selective for lanthanum recovery from hydrocracking spent-catalyst.

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

    Carnahan, T.G.; Lei, K.P.V.

    1979-01-01

    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 100 0 to 110 0 C, (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, HNO 3 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

  3. Roasting and leaching behaviors of vanadium and chromium in calcification roasting-acid leaching of high-chromium vanadium slag

    Wen, Jing; Jiang, Tao; Zhou, Mi; Gao, Hui-yang; Liu, Jia-yi; Xue, Xiang-xin

    2018-05-01

    Calcification roasting-acid leaching of high-chromium vanadium slag (HCVS) was conducted to elucidate the roasting and leaching behaviors of vanadium and chromium. The effects of the purity of CaO, molar ratio between CaO and V2O5 ( n(CaO)/ n(V2O5)), roasting temperature, holding time, and the heating rate used in the oxidation-calcification processes were investigated. The roasting process and mechanism were analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM), and thermogravimetry-differential scanning calorimetry (TG-DSC). The results show that most of vanadium reacted with CaO to generate calcium vanadates and transferred into the leaching liquid, whereas almost all of the chromium remained in the leaching residue in the form of (Fe0.6Cr0.4)2O3. Variation trends of the vanadium and chromium leaching ratios were always opposite because of the competitive reactions of oxidation and calcification between vanadium and chromium with CaO. Moreover, CaO was more likely to combine with vanadium, as further confirmed by thermodynamic analysis. When the HCVS with CaO added in an n(CaO)/ n(V2O5) ratio of 0.5 was roasted in an air atmosphere at a heating rate of 10°C/min from room temperature to 950°C and maintained at this temperature for 60 min, the leaching ratios of vanadium and chromium reached 91.14% and 0.49%, respectively; thus, efficient extraction of vanadium from HCVS was achieved and the leaching residue could be used as a new raw material for the extraction of chromium. Furthermore, the oxidation and calcification reactions of the spinel phases occurred at 592 and 630°C for n(CaO)/ n(V2O5) ratios of 0.5 and 5, respectively.

  4. Selective reductive leaching of cobalt and lithium from industrially crushed waste Li-ion batteries in sulfuric acid system.

    Peng, Chao; Hamuyuni, Joseph; Wilson, Benjamin P; Lundström, Mari

    2018-06-01

    Recycling of valuable metals from secondary resources such as waste Li-ion batteries (LIBs) has recently attracted significant attention due to the depletion of high-grade natural resources and increasing interest in the circular economy of metals. In this article, the sulfuric acid leaching of industrially produced waste LIBs scraps with 23.6% cobalt (Co), 3.6% lithium (Li) and 6.2% copper (Cu) was investigated. The industrially produced LIBs scraps were shown to provide higher Li and Co leaching extractions compared to dissolution of corresponding amount of pure LiCoO 2 . In addition, with the addition of ascorbic acid as reducing agent, copper extraction showed decrease, opposite to Co and Li. Based on this, we propose a new method for the selective leaching of battery metals Co and Li from the industrially crushed LIBs waste at high solid/liquid ratio (S/L) that leaves impurities like Cu in the solid residue. Using ascorbic acid (C 6 H 8 O 6 ) as reductant, the optimum conditions for LIBs leaching were found to be T = 80 °C, t = 90 min, [H 2 SO 4 ] = 2 M, [C 6 H 8 O 6 ] = 0.11 M and S/L = 200 g/L. This resulted in leaching efficiencies of 95.7% for Li and 93.8% for Co, whereas in contrast, Cu extraction was only 0.7%. Consequently, the proposed leaching method produces a pregnant leach solution (PLS) with high Li (7.0 g/L) and Co (44.4 g/L) concentration as well as a leach residue rich in Cu (up to 12 wt%) that is suitable as a feed fraction for primary or secondary copper production. Copyright © 2018 Elsevier Ltd. All rights reserved.

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

    W Widowati

    2014-10-01

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

  6. Counter-current acid leaching process for the removal of Cu, Pb, Sb and Zn from shooting range soil.

    Lafond, Stéphanie; Blais, Jean-François; Mercier, Guy; Martel, Richard

    2013-01-01

    This research explores the performance of a counter-current leaching process (CCLP) for Cu, Pb, Sb and Zn extraction in a polluted shooting range soil. The initial metal concentrations in the soil were 1790 mg Cu/kg, 48,300 mg Pb/kg, 840 mg Sb/kg and 368 mg Zn/kg. The leaching process consisted of five one-hour acid leaching steps, which used 1 M H2SO4 + 4 M NaCl (20 degrees C, soil suspension = 100 g/L) followed by two water rinsing steps. Ten counter-current remediation cycles were completed and the average metal removal yields were 98.3 +/- 0.3% of Cu, 99.5 +/- 0.1% of Pb, 75.5 +/- 5.1% of Sb and 29.1 +/- 27.2% of Zn. The quality of metal leaching did not deteriorate throughout the 10 remediation cycles completed for this study. The CCLP reduced acid and salt use by approximately 68% and reduced water consumption by approximately 60%, exceeding reductions achieved by a standard acid leaching process.

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

    Sminčáková, Emília; Trpčevská, Jarmila; Pirošková, Jana

    2017-10-01

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

  8. Strategies to increase nitrogen use efficiency and reduce nitrate leaching in vegetable production in the Netherlands

    Ruijter, de F.J.; Berge, ten H.F.M.; Smit, A.L.

    2010-01-01

    Environmental concern and legislation of fertilization requires strategies to increase nitrogen use efficiency and reduce nitrate leaching. Strategies can be fertilizer choice, timing of N availability and fertilizer placement. Rainfall in the experimental year 2007 was moderate and different

  9. Leaching of metals from large pieces of printed circuit boards using citric acid and hydrogen peroxide.

    Jadhav, Umesh; Su, C; Hocheng, Hong

    2016-12-01

    In the present study, the leaching of metals from large pieces of computer printed circuit boards (CPCBs) was studied. A combination of citric acid (0.5 M) and 1.76 M hydrogen peroxide (H 2 O 2 ) was used to leach the metals from CPCB piece. The influence of system variables such as H 2 O 2 concentration, concentration of citric acid, shaking speed, and temperature on the metal leaching process was investigated. The complete metal leaching was achieved in 4 h from a 4 × 4 cm CPCB piece. The presence of citric acid and H 2 O 2 together in the leaching solution is essential for complete metal leaching. The optimum addition amount of H 2 O 2 was 5.83 %. The citric acid concentration and shaking speed had an insignificant effect on the leaching of metals. The increase in the temperature above 30 °C showed a drastic effect on metal leaching process.

  10. Leaching behavior and chemical stability of copper butyl xanthate complex under acidic conditions.

    Chang, Yi Kuo; Chang, Juu En; Chiang, Li Choung

    2003-08-01

    Although xanthate addition can be used for treating copper-containing wastewater, a better understanding of the leaching toxicity and the stability characteristics of the copper xanthate complexes formed is essential. This work was undertaken to evaluate the leaching behavior of copper xanthate complex precipitates by means of toxicity characteristics leaching procedure (TCLP) and semi-dynamic leaching test (SDLT) using 1 N acetic acid solution as the leachant. Also, the chemical stability of the copper xanthate complex during extraction has been examined with the studying of variation of chemical structure using UV-vis, Fourier transform infrared and X-ray photoelectron spectroscopies (XPS). Both TCLP and SDLT results showed that a negligible amount of copper ion was leached out from the copper xanthate complex precipitate, indicating that the complex exhibited a high degree of copper leaching stability under acidic conditions. Nevertheless, chemical structure of the copper xanthate complex precipitate varied during the leaching tests. XPS data suggested that the copper xanthate complex initially contained both cupric and cuprous xanthate, but the unstable cupric xanthate change to the cuprous form after acid extraction, indicating the cuprous xanthate to be the final stabilizing structure. Despite that, the changes of chemical structure did not induce the rapid leaching of copper from the copper xanthate complex.

  11. Selective removal of chromium from sulphuric acid leach liquor of ilmenite ore by solvent extraction with trioctylamine

    E.O. Olanipekun

    2000-12-01

    Full Text Available The selective removal of chromium, a trace impurity that degrades the whiteness of titanium(IV oxide pigments, from sulphuric acid leach liquor of ilmenite, was investigated by solvent extraction with xylene solutions of trioctylamine. Important factors of commercial significance affecting the extraction operation have been examined. More than 99% of the chromium was selectively removed in multiple batch extractions from the leach liquor and titanium losses were minimal (< 1%. The chromium content of extracted solutions was reduced to less than 1 ppm and thermal hydrolysis of these solutions yielded white titanium(IV oxide pigments that are suitable for use in the coatings pigment industry.

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

    Esther Phillip; Muhamad Samudi Yasir

    2012-01-01

    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)

  13. Leaching and recovery of zinc and copper from brass slag by sulfuric acid

    I.M. Ahmed

    2016-09-01

    Full Text Available Leaching and recovery processes for zinc and copper from brass slag by sulfuric acid were carried out and iron and aluminum were also precipitated as hydroxides in addition to silica gel. The factors affecting the performance and efficiency of the leaching processsuch as agitation rate, leaching time, acid concentration and temperature were separately investigated. The results obtained revealed that zinc and copper are successfully recovered from these secondary resources, where the percent recovery amounts to 95% and 99% for zinc and copper, respectively. The experimental data of this leaching process were well interpreted with the shrinking core model under chemically controlled processes. The apparent activation energy for the leaching of zinc has been evaluated using the Arrhenius expression. Based on the experimental results, a separation method and a flow sheet were developed and tested to separate zinc, copper, iron, aluminum and silica gel from the brass slag.

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

    Ramadevi, G.; Sreenivas, T.; Navale, A.S.; Padmanabhan, N.P.H.

    2012-01-01

    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 U 3 O 8 content of about 270 mg/L, free acidity 2.4 N H 2 SO 4 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 H 2 SO 4 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 U 3 O 8 . About 98% of the uranium values could be stripped from the loaded organic using 1 N NaCl in 0.2 N H 2 SO 4 . 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)

  15. Nitric acid leaching of radium and other significant radionuclides from uranium ores and tailings

    Ryon, A.D.; Hurst, F.J.; Seeley, F.G.

    1977-08-01

    Nitric acid leaching of representative uranium ores and mill tailings from the western U.S. mining districts removes up to 98% of the 226 Ra and 230 Th, yielding a residue containing 17 to 60 pCi of radium per gram. At best, this is an order of magnitude greater than that in surrounding soils, but about the same level as a standard proposed for building materials in the United Kingdom. Data are also presented on the water penetration and leaching of tailings, the solubility of BaSO 4 , and radon emanation coefficients of ores, tailings, and nitric acid-leached residues

  16. Multistage leaching of metals from spent lithium ion battery waste using electrochemically generated acidic lixiviant.

    Boxall, N J; Adamek, N; Cheng, K Y; Haque, N; Bruckard, W; Kaksonen, A H

    2018-04-01

    Lithium ion battery (LIB) waste contains significant valuable resources that could be recovered and reused to manufacture new products. This study aimed to develop an alternative process for extracting metals from LIB waste using acidic solutions generated by electrolysis for leaching. Results showed that solutions generated by electrolysis of 0.5 M NaCl at 8 V with graphite or mixed metal oxide (MMO) electrodes were weakly acidic and leach yields obtained under single stage (batch) leaching were poor (leaching with the graphite electrolyte solution improved leach yields overall, but the electrodes corroded over time. Though yields obtained with both electrolyte leach solutions were low when compared to the 4 M HCl control, there still remains potential to optimise the conditions for the generation of the acidic anolyte solution and the solubilisation of valuable metals from the LIB waste. A preliminary value proposition indicated that the process has the potential to be economically feasible if leach yields can be improved, especially based on the value of recoverable cobalt and lithium. Copyright © 2018 Elsevier Ltd. All rights reserved.

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

    Feng Yu; An Wei; Chen Shusen

    2014-01-01

    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)

  18. Study of radium extraction mechanisms from scales by leaching in different acidic and alkaline media

    Al-Masri, M. S.; Gafar, M.; Al-Kurdi, H.

    2002-07-01

    The present report shows the results of leaching experiments for scales containing naturally occuring radioactive materials using different acidic and alkaline media. The obtained result can be used for defining the method of safe disposal of such waste. Leaching solutions used in this study were distilled water, mineral acids (sulpharic acid, hydrochloric acid and nitric acid), sodium, potassium hydroxides, ammonium oxalate EDTA, sodium carbonate, potassium acetate, and a mixture of potassium chloride and hydrochloric acid. The results have shown that the extraction ratio of radium-226, the most abundant isotope in scales, is very low and even negligible using all different media. This indicates that all scales produced in Syrian oil fields do not require any chemical preparation before disposal. In addition, the effect of both stirring time of phrases and concentration of leaching media that may affect the radium transfer process from solid phase to aqueous phase have been investigated were no measurable amount being observed in the leachate. (author)

  19. Evaluating Nitrogen Management Options for Reducing Nitrate Leaching from Northeast U.S. Pastures

    William L. Stout

    2001-01-01

    Full Text Available Substantial amounts of nitrate nitrogen NO3-N can leach from intensively grazed pasture in the northeast U.S. where there is about 30 cm of groundwater recharge, annually. Management options for reducing NO3-N leaching were evaluated for this environment using the Cornell Net Carbohydrate and Protein System Model and a recently developed nitrogen leaching index. Management options utilizing energy supplementation of grazing dairy cows could improve nitrogen efficiency within the cow, but would not necessarily reduce NO3-N leaching at the pasture scale if stocking rate was not controlled. The management option of using white clover to supply nitrogen to the pasture decreased NO3-N leaching, but produced less dry matter yield, which in turn reduced stocking rate. The economic returns of reducing NO3-N with these options need to be evaluated in light of milk prices and commodity and fertilizer nitrogen costs. At current prices and costs, the economic benefit from the energy supplementation options is substantial.

  20. Extraction of magnesium from calcined dolomite ore using hydrochloric acid leaching

    Royani, Ahmad; Sulistiyono, Eko; Prasetiyo, Agus Budi; Subagja, Rudi

    2018-05-01

    Magnesium is widely used in varieties industrial sector. Dolomite is one source of magnesium besides seawater. The extraction of magnesium from dolomite ores can be done by leaching process. In this work, the dolomite leaching to extract magnesium by hydrochloric acid was investigated. The leaching experiments were performed in a spherical glass batch reactor having a capacity of 1000 ml. The effects of the stirring speed, acid concentration, reaction temperature and liquid-solid ratio for each reaction time of 1; 2; and 3 h on the Mg leaching have been evaluated. 5 ml of solution sample were collected from the leached solutions, then it was filtered prior to analysis by ICP OES. The experimental results show that the magnesium extraction increases along with the increase of acid concentration, liquid-solid ratio and temperature. The optimum conditions for magnesium extraction were achieved at temperature 75 °C, extraction time 3 h, the HCl concentration of 2 M, the liquid-solid ratio 20 ml/g and stirring speed of 400 rpm. At this condition 98, 82 % of magnesium were extracted from dolomite. The conclusion obtained from this leaching process is that the magnesium can be extracted from dolomite by using hydrochloric acid solutions.

  1. A Mineralogical Assessment on Residues after Acidic Leaching of Bauxite Residue (Red Mud for Titanium Recovery

    Gözde Alkan

    2017-10-01

    Full Text Available Due to its alkalinity, red mud produced by the Bayer process may affect both the environment and human health. For this reason, its further utilization instead of disposal is of great importance. Numerous methods have already been studied for hydrometallurgical treatment of red mud, especially for the recovery of various metallic components such as iron, aluminum, titanium or rare earth elements. This study focuses on the extraction of titanium from red mud and in particular the mineralogical changes, induced by leaching. Sulfuric acid, hydrochloric acid and their combination have been utilized as leaching agents with the same leaching parameters. It has been determined that sulfuric acid is the best candidate for the red mud treatment in terms of titanium leaching efficiency at the end of 2 h with a value of 67.3%. Moreover, samples from intermediate times of reaction revealed that leaching of Ti exhibit various reaction rates at different times of reaction depending on acid type. In order to explain differences, X-ray Diffraction (XRD, scanning electron microscope (SEM and QEMSCAN techniques were utilized. Beside titanium oxide (TiO2 with available free surface area, a certain amount of the TiO2 was detected as entrapped in Fe dominating oxide. These associations between Ti and Fe phases were used to explain different leaching reaction rates and a reaction mechanism was proposed to open a process window.

  2. Multistage dilute acid leaching of a medium grade iron ore to super-concentrate

    Adeleke A.A.

    2014-01-01

    Full Text Available The phosphorous laden Koton Karfe iron ore is a medium grade iron ore deposit in Nigeria that can be upgraded as a super-concentrate for use at the Aladja Steel Midrex plant. The 75 μm size sample fraction of the ore was preconcentrated with shaking table and leached in the oven at atmospheric pressure with dilute hydrochloric acid in single and multistage leaching sequences of H2O-HCl-H2O and HCl-H2O-H2O. The as-received, as-tabled and asleached samples were then subjected to X-ray fluorescence and microscopic analyses. The results obtained showed that the H2O-HCl-H2O route produced a higher grade concentrate that assayed 68.54% Fe indicating about 58% upgrade in iron content; while the phosphorus and sulphur contents were reduced by about 77 and 99.6% respectively. In addition, the silicon, manganese, and titanium contents were drastically reduced, while potassium was completely eliminated. The upgrade of iron content in the ore to 68.54% and the drastic reduction in phosphorous and sulphur contents has thus rendered the Koton Karfe iron ore suitable for use as a super concentrate for the Aladja steel plant direct reduction iron making process.

  3. 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

    Fatemi, K.

    2003-01-01

    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 s eawater i n uranium extraction from salted, compared with the n ormal or sweat water h as 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

  4. Leaching kinetic of Nd. Y, Pr and Sm in rare earth hydroxide (REOH) use nitric acid

    Purwani, MV; Suyanti

    2018-02-01

    The purpose of this study were to determine the order of reaction, rate reaction constant and activation energy of reaction Y(OH)3, Nd(OH)3, Pr(OH)3 and Sm(OH)3 with HNO3. The rate reaction constant is necessary to determine the residence time in the design of continuously stirred tank reactor (CSTR). The studied parameters were leaching temperature (60 - 90 °C) and leaching time (0-15 minutes). From the resulting data can be concluded that the leaching process were strongly influenced by the time and temperature process. Leaching rare earth hydroxide (REOH) using nitric acid follows second order. At leaching 10 grams of REOH using 40 ml HNO3 0.0576 mol were obtained maximum conversion at 90 °C and leaching time 15 minutes for Y was 0.95 (leaching efficiency was 95%), for Nd was 0.97 ( leaching efficiency was 97%), for Pr was 0.94 (leaching efficiency was 94%) and for Sm was 0.94 (leaching efficiency was 94%). The largest activation energy was Y of 23.34 kJ/mol followed by Pr of 20.00 kJ/mol, Sm of 17.94 kJ/mol and the smallest was Nd of 16.39 kJ/mol. The relationship between the rate constant of the reaction with T for Y was kY = 338.26 e-23,34/RT, for Nd was kNd = 33.69 e -16,39 / RT, for Pr was kPr = 102.04 e-20 / RT and for Sm adalah was kSm = 50.16 e-17,94/RT

  5. LEACHING AND DEGRADATION OF 2,4-DICHLOROPHENOXIACETIC ACID, IN COLOMBIA RICE FLOODED SOIL.

    Huertas, J; Guerrero, J A; Martinez-Cordon, M J

    2015-01-01

    Rice is mostly cultivated on soil held under flooded conditions. Under these conditions pesticides undergo reductive transformations which are characteristic to rice fields and other anaerobic systems. The present study was undertaken to evaluate the mobility and persistence of 2,4-dichlorophenoxy acetic acid (2,4-D) under laboratory conditions for the rice crop in Espinal, Colombia. A displacement study was performed on a hand packed soil column 30 cm length. After leaching experiment, the soil from column was sliced into six successive sections (5 cm). Methanol acidified (H3PO4 0.25%) extraction was used to determine the herbicide residues in each section. 2,4-D experimental breakthrough curve was analyzed using Stanmod program (inverse problem) to obtain transport parameters. The non-equilibrium physical model fitted well the experimental breakthrough curve. The recovery percent of 2,4-D in leachates was 36.44% after 3.4 pore volumes, and retardation factor was 2.1, indicating low adsorption in that conditions. 2,4-D was rapidly degraded, with DT50 = 11.4 days. The results suggest that 2,4-D under flooded conditions have a high potential for leaching through the soil profile, although the elevated rate of degradation reduced the ground water contamination risk.

  6. Lead isotope results of acid leaching experiments on acid volcanics and black shales in an ore environment

    Gulson, B.L.

    1977-01-01

    In the volcanogenic Woodlawn Cu-Pb-Zn deposit, where pyrite is the dominant sulphide phase in the ore and a ubiquitous mineral in the host volcanics and shales, leaching experiments using HNO 3 -HCl to overcome the ore/rock lead dominance, resulted in highly complex lead isotopic data, dependent mainly on the original lead concentration in the rock. For samples with higher (> 5 ppm) lead concentrations, the acid leaches are less radiogenic than the rocks or residues whereas for samples with 15 ppm lead, the data arrays are those expected for a dominance of ore/rock lead. In all except the very high lead samples (> 100 ppm), lead is derived from sources other than sulphides. Furthermore, in only the highest lead sample is the acid leach isotopic value compatible with that of the ore lead. As found in previous leaching investigations, the dominant component of lead and uranium is extracted in the acid leach. Acid-leaching experiments of this type may have possible applications in prospecting for basemetal sulphides. (auth.)

  7. Acid mine drainage simulated leaching behavior of goethite and cobalt substituted goethite

    Penprase, S. B.; Kimball, B. E.

    2015-12-01

    Though most modern day mining aims to eliminate the seepage of acid mine drainage (AMD) to the local watershed, historical mines regularly receive little to no remediation, and often release acidic, metal-rich drainage and particles to the environment. Treatment of AMD often includes neutralizing pH to facilitate the precipitation of Fe-oxides and dissolved trace metals, thereby forming Trace Metal Substituted (TMS) forms of known minerals, such as goethite (α-FeOOH). The stability of TMS precipitates is not fully understood. As a result, we conducted a 20 day leach experiment using laboratory synthesized pure (Gt) and cobalt-substituted (CoGt) goethites with a dilute ultrapure HCl solution (pH = 3.61) at T = 23.3±2.5ºC. Leached solids were characterized using X-ray diffraction (XRD) and scanning electron microscopy paired with energy dispersive spectroscopy (SEM-EDS). Leach solutions were sampled for pH and conductivity, and dissolved chemistry was determined with Inductively Coupled Plasma Mass Spectroscopy (ICP-MS). Preliminary results indicate Gt and CoGt filtered leach solutions experienced constant pH (Gt = 3.9 ± 0.1, CoGt = 6.8 ± 0.2) and conductivity (Gt = 69 ± 6.6 μS/cm, CoGt = 81 ± 16 μS/cm) for t = 0-20 days. Micro-focused XRD results indicate that leached solids did not change in mineralogy throughout the experiment, and SEM images show minor disintegration along mineral grain edges, but little overall change in shape. Preliminary ICP-MS results show lower dissolved Fe concentrations for CoGt (1.1 ± 1.1 ppb) compared to Gt (17 ± 8.9 ppb) over time. Dissolved Co concentrations ranged from 560 - 830 ppb and increased over time. Compared to leaching of pure Gt, leaching of CoGt generated significantly higher pH, slightly higher conductivity, and significantly less dissolved Fe. During the CoGt leach, Co was preferentially leached over Fe. The differences in leaching behavior between pure and TMS goethite in the laboratory have implications for

  8. Nickel-cadmium batteries: effect of electrode phase composition on acid leaching process.

    Nogueira, C A; Margarido, F

    2012-01-01

    At the end of their life, Ni-Cd batteries cause a number of environmental problems because of the heavy metals they contain. Because of this, recycling of Ni-Cd batteries has been carried out by dedicated companies using, normally, pyrometallurgical technologies. As an alternative, hydrometallurgical processes have been developed based on leaching operations using several types of leachants. The effect of factors like temperature, acid concentration, reaction time, stirring speed and grinding of material on the leaching yields of metals contained in anodic and cathodic materials (nickel, cadmium and cobalt) using sulphuric acid, is herein explained based on the structural composition of the electrode materials. The nickel, cobalt and cadmium hydroxide phases, even with a small reaction time (less than 15 minutes) and low temperature (50 degrees C) and acid concentration (1.1 M H2SO4), were efficiently leached. However, leaching of the nickel metallic phase was more difficult, requiring higher values of temperature, acid concentration and reaction time (e.g. 85 degrees C, 1.1 M H2SO4 and 5 h, respectively) in order to obtain a good leaching efficiency for anodic and cathodic materials (70% and 93% respectively). The stirring speed was not significant, whereas the grinding of electrode materials seems to promote the compaction of particles, which appears to be critical in the leaching of Ni degrees. These results allowed the identification and understanding of the relationship between the structural composition of electrode materials and the most important factors that affect the H2SO4 leaching of spent Ni-Cd battery electrodes, in order to obtain better metal-recovery efficiency.

  9. Reducing nitrogen leaching from fertilizers to surface waters: catchment specific indicators of economic benefits

    Andersen, Mikael Skou; Levin, Gregor; Odgaard, Mette Vestergaard

    2018-01-01

    We explore with impact pathway methodology the economic benefits of reducing nitrogen leaching to transitional surface waters, as expected for a proportionality test under the EU’s Water Framework Directive article 4. Ten different catchments is analyzed for a policy scenario where downstream dis...

  10. Intensified Vegetation Water Use due to Soil Calcium Leaching under Acid Deposition

    Lanning, M.; Wang, L.; Scanlon, T. M.; Vadeboncoeur, M. A.; Adams, M. B.; Epstein, H. E.; Druckenbrod, D.

    2017-12-01

    Despite the important role vegetation plays in the global water cycle, the exact controls of vegetation water use, especially the role of soil biogeochemistry, remain elusive. Nitrate and sulfate deposition from fossil fuel burning has caused significant soil acidification, leading to the leaching of soil base cations. From a physiological perspective, plants require various soil cations as signaling and regulatory ions as well as integral parts of structural molecules; a depletion of soil cations can cause reduced productivity and abnormal responses to environmental change. A deficiency in calcium could also potentially prolong stomatal opening, leading to increased transpiration until enough calcium had been acquired to stimulate stomatal closure. Based on the plant physiology and the nature of acidic deposition, we hypothesize that depletion of the soil calcium supply, induced by acid deposition, would intensify vegetation water use at the watershed scale. We tested this hypothesis by analyzing a long-term and unique data set (1989-2012) of soil lysimeter data along with stream flow and evapotranspiration data at the Fernow Experimental Forest. We show that depletion of soil calcium by acid deposition can intensify vegetation water use ( 10% increase in evapotranspiration and depletion in soil water) for the first time. These results are critical to understanding future water availability, biogeochemical cycles, and surficial energy flux and may help reduce uncertainties in terrestrial biosphere models.

  11. Bio- and mineral acid leaching of rare earth elements from synthetic phosphogypsum

    Hu, Z.; Antonick, P.; Fujita, Y.; Reed, D. W.; Riman, R.; Eslamimanesh, A.; Das, G.; Anderko, A.; Wu, L.; Shivaramaiah, R.; Navrotsky, A.

    2017-12-01

    Rare earth elements (REE) are critical to many clean energy technologies. However, the lack of U.S. domestic production and the reliance on imported REE put U.S. energy security at risk. Consequently development of new sources is of strategic interest. Global phosphate deposits contain 27 million tons of REE and 38% of these REE end up in phosphogypsum (PG) waste during phosphate fertilizer production. Recovering REE from PG is a first step toward a trash-to-treasure transformation. We studied the leaching of REE from synthetic PG samples containing Y, Nd, or Eu using a suite of lixiviants including spent medium from the growth of the bacterium Gluconobacter oxydans ("biolixiviant"), gluconic acid, common mineral acids (phosphoric and sulfuric), and water. Synthetic PG was used to facilitate the comparison of the different lixiviants; real PG waste is extremely heterogeneous. Gluconic acid was the predominant identified organic acid in the biolixiviant. The leaching efficiency of the acidic lixiviants at the same pH (2.1) or molar concentration as gluconic acid in the biolixiviant (220 mM) were compared and rationalized by thermodynamic simulation using the mixed-solvent electrolyte model. Initial results indicate that the biolixiviant was more effective at leaching the REE than the mineral acids at pH 2.1. At 220 mM acid concentrations, sulfuric acid was the most effective, followed by the biolixiviant. Interestingly, for a given lixiviant, the leaching behavior of the REE differed. This study provides insight into the definition of an efficient lixiviant for leaching REE from phosphate fertilizer production waste.

  12. Decontamination of Soils Contaminated with Co and Cs by Using an Acid Leaching Process

    Jung-Joon, Lee; Gye-Nam, Kim; Jei-Kwon, Moon; Kune-Woo, Lee

    2009-01-01

    Acid leaching process has been adapted for the remediation of soils contaminated with heavy metals and radionuclides. This method has been reported to be simple, and economically promising. Moreover it can be applicable for on-site and off-site remediations as well. Investigations were conducted on an acid leaching process using surrogate contaminated soils. Size sieving, agglomeration and column leaching were carried out with soils artificially contaminated with Co and Cs, respectively. Size distribution was analyzed for a determination of the particle size required to be agglomerated. Because of the low water permeability of the soils due to their fine particles, they were sieved by using a sieve with a 0.075 mm size (No. 200 mesh) for an agglomeration. The soils with a size smaller than 0.075 mm were agglomerated by using 2 % sodium silicate (Na 2 SiO 3 ), while the soils with a size larger than 0.075 mm were used directly for the column leaching test. From the preliminary test (the batch scale leaching test), 0.1 M of HCl was determined as the effective leaching agent for Co and Cs. Finally, the soils mixed with the coarse soil and the agglomerated soil were decontaminated with 0.1 M HCl within 11.3 days and the removal efficiencies of Co and Cs were 94.0 % and 82.8 %, respectively. In conclusion, an acid leaching process could be applied for a remediation of soils contaminated with radionuclides such as Co and Cs. (authors)

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

    Mahdy, M.A.

    1988-01-01

    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

  14. Recovery of Iron from Pyrolusite Leaching Slag by a Lab-Scale Circulation Process of Oxalic Acid Leaching and Ultraviolet Irradiation

    Biao Deng

    2017-12-01

    Full Text Available Pyrolusite leaching slag is a Fe-containing slag generated from pyrolusite leaching process with SO2. Recovery of iron from the slag not only has economic benefit, but also prevents the secondary pollution to the environment. A novel lab-scale cyclic process for recovering iron from pyrolusite leaching slag was introduced. The process contains two steps: (1 iron was leached with oxalic acid and [Fe(C2O4n](3−2n+ solution was generated; (2 the [Fe(C2O4n](3−2n+ solution was irradiated by ultraviolet and ferrous oxalate precipitation were obtained. The effect of operation parameter on leaching and irradiation process were studied separately. In the leaching process, the optimal solid/liquid ratio, oxalic acid concentration, leaching temperature, stirring rate, and leaching time are 1:50, 0.40 mol/L, 95 °C, 300 r/min, and 3 h, respectively. In the irradiation process, the best irradiation wavelength, Fe/oxalic acid molar ratio and irradiation time are 254 nm, 1:4, and 30 min. Besides, a test of 9 continuous cycles was carried out and the performance and material balance of the combined process were investigated. The results showed that the cyclic process is entirely feasible and prove to be stable producing, and ferrous oxalate of 99.32% purity. Material balance indicated that 95.17% of iron was recovered in the form of FeC2O4·2H2O, and the recovery efficiency of oxalic acid was 58.52%.

  15. Leaching and accumulation of trace elements in sulfate reducing granular sludge under concomitant thermophilic and low pH conditions

    Gonzalez-Gil, Graciela; Lopes, Sí lvia I C; Saikaly, Pascal; Lens, Piet Nl L

    2012-01-01

    The leaching and/or accumulation of trace elements in sulfate reducing granular sludge systems was investigated. Two thermophilic up-flow anaerobic sludge bed (UASB) reactors operated at pH 5 were fed with sucrose (4gCODl reactor -1d -1) and sulfate at different COD/SO 4 2- ratios. During the start-up of such acidogenic systems, an initial leaching of trace elements from the inoculum sludge occurred regardless of trace elements supplementation in the reactor influent. The granular sludge maintained the physical structure despite high Fe leaching. After start-up and nonetheless the acidic conditions, Co, Ni, Cu, Zn, Mo and Se were retained or accumulated by the sludge when added. Particularly, Ni and Co accumulated in the carbonates and exchangeable fractions ensuring potential bioavailability. Otherwise, the initial stock in the inoculum sludge sufficed to operate the process for nearly 1year without supplementation of trace elements and no significant sludge wash-out occurred. © 2012 Elsevier Ltd.

  16. Leaching and accumulation of trace elements in sulfate reducing granular sludge under concomitant thermophilic and low pH conditions

    Gonzalez-Gil, Graciela

    2012-12-01

    The leaching and/or accumulation of trace elements in sulfate reducing granular sludge systems was investigated. Two thermophilic up-flow anaerobic sludge bed (UASB) reactors operated at pH 5 were fed with sucrose (4gCODl reactor -1d -1) and sulfate at different COD/SO 4 2- ratios. During the start-up of such acidogenic systems, an initial leaching of trace elements from the inoculum sludge occurred regardless of trace elements supplementation in the reactor influent. The granular sludge maintained the physical structure despite high Fe leaching. After start-up and nonetheless the acidic conditions, Co, Ni, Cu, Zn, Mo and Se were retained or accumulated by the sludge when added. Particularly, Ni and Co accumulated in the carbonates and exchangeable fractions ensuring potential bioavailability. Otherwise, the initial stock in the inoculum sludge sufficed to operate the process for nearly 1year without supplementation of trace elements and no significant sludge wash-out occurred. © 2012 Elsevier Ltd.

  17. Effect of acid leaching conditions on impurity removal from silicon doped by magnesium

    Stine Espelien

    2017-07-01

    Full Text Available The effect of magnesium addition into a commercial silicon and its leaching refining behavior is studied for producing solar grade silicon feedstock. Two different levels of Mg is added into a commercial silicon and the leaching of the produced alloys by 10% HCl solution at 60 ℃ for different durations is performed. It is shown that the microstructure of the alloy and in particular the distribution of eutectic phases is dependent on the amount of the added Mg. Moreover, the metallic impurities in silicon such as Fe, Al, Ca and Ti are mainly forming silicide particles with different compositions. These silicides are physically more detached from the primary silicon grains and their removal through chemical and physical separation in leaching is better for higher Mg additions. It is observed that the leaching is more effective for the purification of smaller silicon particles produced from each Mg-doped silicon alloy. It is shown that acid leaching by the applied method is effective to reach more than 70% of phosphorous removal. It is also shown that the purity of silicon is dependent on the total Mg removal and effectiveness of leaching on removing the Mg2Si phase.

  18. Titanium leaching from red mud by diluted sulfuric acid at atmospheric pressure

    Agatzini-Leonardou, S.; Oustadakis, P.; Tsakiridis, P.E.; Markopoulos, Ch.

    2008-01-01

    Laboratory-scale research has focused on the recovery of titanium from red mud, which is obtained from bauxite during the Bayer process for alumina production. The leaching process is based on the extraction of this element with diluted sulfuric acid from red mud under atmospheric conditions and without using any preliminary treatment. Statistical design and analysis of experiments were used, in order to determine the main effects and interactions of the leaching process factors, which were: acid normality, temperature and solid to liquid ratio. The titanium recovery efficiency on the basis of red mud weight reached 64.5%. The characterization of the initial red mud, as well as this of the leached residues was carried out by X-ray diffraction, TG-DTA and scanning electron microscopy

  19. Impact of simulated acid rain on trace metals and aluminum leaching in latosol from Guangdong Province, China

    Jia-En Zhang; Jiayu Yu; Ying Ouyang; Huaqin. Xu

    2014-01-01

    Acid rain is one of the most serious ecological and environmental problems worldwide. This study investigated the impacts of simulated acid rain (SAR) upon leaching of trace metals and aluminum (Al) from a soil. Soil pot leaching experiments were performed to investigate the impacts of SAR at five different pH levels (or treatments) over a 34-day period upon the...

  20. 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

  1. Rare earth elements leaching from Tin slag using Acid Chloride after Alkaline fusion process

    Kurnia Trinopiawan; Budi Yuli Ani; June Mellawati; Mohammad Zaki Mubarok

    2016-01-01

    Tin slag, a waste product from tin smelting process, has a potency to be utilized further by extracting the valuable metals inside, such as rare earth elements(REE). The objective of this study is to determine the optimum leaching condition of REE from tin slag after alkali fusion. Silica structure in slag is causing the direct leaching uneffectively. Therefore, pre-treatment step using alkali fusion is required to break the structure of silica and to increase the porosity of slag. Fusion is conducted in 2 hours at 700°C, with ratio of natrium hydroxide (NaOH) : slag = 2 : 1. Later, frit which is leached by water then leached by chloride acid to dissolve REE. As much as 87,5% of REE is dissolved at 2 M on chloride acid (HCl) concentration, in 40°C temperature, -325 mesh particle size, 15 g/100 ml of S/L, 150 rpm of agitation speed, and 5 minutes of leaching time. (author)

  2. Slag Treatment Followed by Acid Leaching as a Route to Solar-Grade Silicon

    Meteleva-Fischer, Y.V.; Yang, Y.; Boom, R.; Kraaijveld, B.; Kuntzel, H.

    2012-01-01

    Refining of metallurgical-grade silicon was studied using a process sequence of slag treatment, controlled cooling, and acid leaching. A slag of the Na2O-CaO-SiO2 system was used. The microstructure of grain boundaries in the treated silicon showed enhanced segregation of impurities, and the

  3. 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%.

  4. Removing ferric ions from concentrated acid leaching solution of an uranium ore by jarosite

    Song Huanbi; Hu Yezang

    1997-01-01

    The author expounds the fundamental rules of removing ferric ions by jarosite and presents results of removing ferric ions from concentrated acid curing-trickle leaching solution of an uranium ore. It turns out that the method can be applied to uranium hydrometallurgical process effectively

  5. Leaching mechanisms of constituents from fly ash under the influence of humic acid.

    Zhao, Shengxin; Chen, Zhonglin; Shen, Jimin; Kang, Jing; Zhang, Jin; Shen, Yanqing

    2017-01-05

    As a low-cost material for adsorption, FA is one of the most efficient adsorbents of HA. However, the leaching of elements from FA is problematic during utilization in water treatment. In this investigation, the potential leaching behaviors of Calcium, Arsenic, Born, Chromium, and other elements from FA in HA solution were studied via batch test. The data show that HA had an effect on the leaching of each element of FA, depending on the pH, the initial concentration of HA and the addition of calcium oxide (CaO). The Langmuir isotherm could better fit the equilibrium data in different initial concentrations of HA from 10 to 100mg/L. Because of the interaction between HA and the FA leaching elements, multi-layer adsorption occurred when the initial concentration of HA was more than 100mg/L. The pH and free CaO content played major roles in HA adsorption and FA leaching. Using SEM and XRD to characterize the solid of FA being mixed with CaO treated in solution, the results demonstrated that the reaction between FA and CaO could generate crystal minerals, such as portlandite, gismondine, ettringite (AFt) and calcite, which effectively restrained the leaching of elements, reduced secondary pollution. Copyright © 2016 Elsevier B.V. All rights reserved.

  6. Study on copper kinetics in processing sulphide ore mixed with copper and zinc with sulfuric acid leaching under pressure

    Wen-bo, LUO; Ji-kun, WANG; Yin, GAN

    2018-01-01

    Sulphide ore mixed with copper and zinc is processed with pressure acid leaching. Research is conducted on the copper kinetic. The stirring rate is set at 600 rpm which could eliminate the influence of external diffusions. Research is conducted on the factors affecting the copper leaching kinetic are temperature, pressure, concentration of sulfuric acid, particle size. The result shows that the apparent activity energy is 50.7 KJ/mol. We could determine that the copper leaching process is shrinking core model of chemical reaction control and work out the leaching equation.

  7. Separation of Rhenium from Lead-Rich Molybdenite Concentrate via Hydrochloric Acid Leaching Followed by Oxidative Roasting

    Guanghui Li

    2016-11-01

    Full Text Available Lead-rich molybdenite is a typical rhenium-bearing molybdenum resource in China, which has not been efficiently utilized due to its high contents of lead and gangue minerals. In this study, hydrochloric acid was used for preliminarily removing lead and calcite from a lead-rich molybdenite concentrate. Oxidative roasting-ammonia leaching was then carried out for separation of rhenium and extraction of molybdenum. The hydrochloric acid leaching experiments revealed that 93.6% Pb and 97.4% Ca were removed when the leaching was performed at 95 °C for 10 min with HCl concentration of 8 wt. % and liquid-solid ratio of 5 (mL/g. The results of direct oxidative roasting indicated that 89.3% rhenium was volatilized from the raw concentrate after roasting at 600 °C for 120 min in air. In contrast, the rhenium volatilization was enhanced distinctly to 98.0% after the acid-leached concentrate (leaching residue was roasted at 550 °C for 100 min. By the subsequent ammonia leaching, 91.5% molybdenum was leached out from the calcine produced from oxidative roasting of the acid-leached concentrate, while only 79.3% Mo was leached from the calcine produced by roasting molybdenite concentrate without pretreatment.

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

    Abdulbaki, M.; Stas, J.; Shino, O.; Asaad, K.; Al-Kassemi, H.; Al-Qabani, F.

    2008-01-01

    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 (Na 2 CO 3 , (NH 4 )CO 3 and NH 4 OH) 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)

  9. Experimental Study and Reactive Transport Modeling of Boric Acid Leaching of Concrete

    Chiang K.-T. K.

    2013-07-01

    Full Text Available Borated water leakage through spent fuel pools (SFPs at pressurized water reactors is a concern because it could cause corrosion of reinforcement steel in the concrete structure, compromise the integrity of the structure, or cause unmonitored releases of contaminated water to the environment. Experimental data indicate that pH is a critical parameter that determines the corrosion susceptibility of rebar in borated water and the degree of concrete degradation by boric acid leaching. In this study, reactive transport modeling of concrete leaching by borated water was performed to provide information on the solution pH in the concrete crack or matrix and the degree of concrete degradation at different locations of an SFP concrete structure exposed to borated water. Simulations up to 100 years were performed using different boric acid concentrations, crack apertures, and solution flow rates. Concrete cylinders were immersed in boric acid solutions for several months and the mineralogical changes and boric acid penetration in the concrete cylinder were evaluated as a function of time. The depths of concrete leaching by boric acid solution derived from the reactive transport simulations were compared with the measured boric acid penetration depth.

  10. In situ leaching of uranium

    Martin, B.

    1980-01-01

    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)

  11. Leaching of cell wall components caused by acid deposition on fir needles and trees

    Shigihara, Ado [Department of Material and Life Chemistry, Faculty of Engineering, Kanagawa University, 3-27-1, Rokkakubashi, Kanagawa-ku, Yokohama 221-8686 (Japan)], E-mail: r200670202@kanagawa-u.ac.jp; Matsumoto, Kiyoshi [Department of Material and Life Chemistry, Faculty of Engineering, Kanagawa University, 3-27-1, Rokkakubashi, Kanagawa-ku, Yokohama 221-8686 (Japan); Sakurai, Naoki [Faculty of Integrated Arts and Science, Hiroshima University, 1-7-1, Kagamiyama, Higashi-Hiroshima, 739-8521 (Japan); Igawa, Manabu [Department of Material and Life Chemistry, Faculty of Engineering, Kanagawa University, 3-27-1, Rokkakubashi, Kanagawa-ku, Yokohama 221-8686 (Japan)

    2008-07-15

    Virgin fir forests have been declining since the 1960s at Mt. Oyama, which is located at the eastern edge of the Tanzawa Mountains and adjacent to the Kanto plain in Japan. An acid fog frequently occurs in the mountains. We collected throughfall and stemflow under fir trees and rainfall every week during January-December 2004 at Mt. Oyama to clarify the influence of acid fog on the decline of fir (Abies firma) needles. In relation to throughfall and stemflow, D-mannose, D-galactose, and D-glucose are the major neutral sugar components; only D-glucose is a major component of rainfall. The correlation coefficient between the total neutral sugars and uronic acid (as D-galacturonic acid), which is a key component of the cross-linking between pectic polysaccharides, was high except for rainfall. The leached amount of calcium ion, neutral sugars, uronic acid, and boron is related to the nitrate ion concentration in throughfall. Results of a laboratory exposure experiment using artificial fog water simulating the average composition of fog water observed at Mt. Oyama (simulated acid fog: SAF) on the fir seedling needles also shows a large leaching of these components from the cell walls of fir needles. The leaching amount increased concomitantly with decreasing pH of the SAF solution. We also observed that a dimeric rhamnogalacturonan II-borate complex (dRG-II-B) that exists in the cell wall as pectic polysaccharide was converted to monomeric RG-II (mRG-II) by the leaching of calcium ion and boron. Results not only of field observations but also those of laboratory experiments indicate a large effect of acid depositions on fir needles.

  12. Density Functional Theory Study of Leaching Performance of Different Acids on Pyrochlore (100) Surface

    Yang, Xiuli; Fang, Qing; Ouyang, Hui

    2018-06-01

    Pyrochlore leaching using hydrofluoric, sulfuric, and hydrochloric acids has been studied via experimental methods for years, but the interactions between niobium atoms on the pyrochlore surface and different acids have not been investigated. In this work, first-principles calculations based on density functional theory were used to elucidate the leaching performance of these three acids from the viewpoint of geometrical and electronic structures. The calculation results indicate that sulfate, chloride, and fluoride anions influence the geometric structure of pyrochlore (100) to different extents, decreasing in the order: sulfate, fluoride, chloride. Orbitals of O1 and O2 atoms of sulfate hybridized with those of surface niobium atom. Fluorine orbitals hybridized with those of surface niobium atoms. However, no obvious overlap exists between any orbitals of chlorine and surface niobium, revealing that chlorine does not interact chemically with surface niobium atoms.

  13. Heavy metal recovery from electric arc furnace steel slag by using hydrochloric acid leaching

    Wei, Lim Jin; Haan, Ong Teng; Shean Yaw, Thomas Choong; Chuah Abdullah, Luqman; Razak, Mus'ab Abdul; Cionita, Tezara; Toudehdehghan, Abdolreza

    2018-03-01

    Electric Arc Furnace steel slag (EAFS) is the waste produced in steelmaking industry. Environmental problem such as pollution will occur when dumping the steel slag waste into the landfill. These steel slags have properties that are suitable for various applications such as water treatment and wastewater. The objective of this study is to develop efficient and economical chlorination route for EAFS extraction by using leaching process. Various parameters such as concentration of hydrochloric acid, particle size of steel slag, reaction time and reaction temperature are investigated to determine the optimum conditions. As a result, the dissolution rate can be determined by changing the parameters, such as concentration of hydrochloric acid, particle size of steel slag, reaction time and reaction temperature. The optimum conditions for dissolution rates for the leaching process is at 3.0 M hydrochloric acid, particle size of 1.18 mm, reaction time of 2.5 hour and the temperature of 90°C.

  14. 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 12h 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. Copyright © 2016 Elsevier B.V. All rights reserved.

  15. Recovery TiO2 by leaching process of carbothermic reduced Kalimantan ilmenite

    Wahyuningsih, S.; Sari, P. P.; Ramelan, A. H.

    2018-05-01

    Ilmenite naturally occurred in iron titanate (FeTiO3) minerals. The separation of natural ilmenite into TiO2 and Fe2O3 need to be explored to gain the high purity separation product. A new combination method named of carbothermic reduction, acidic-leaching and complexation by EDTA were proposed for separation TiO2 from Ilmenite. Roasting of ilmenite was carried out at 950 °C for 1 h by the addition of activated carbon with mass ratio of ilmenite : activated carbon =4:3. The carbothermic reduction was carried out to yield a high separation of initial content of ilmenite that will be easily to dissolve within hydrochloric acid solution in leaching process. The composition of ilmenite observed by X-Ray Fluoresences (XRF) changed after the carbothermic reduction process and the dominant content is TiO2 (57.56%). X-Ray Diffraction (XRD) of roasted ilmenite composed of decomposed product of ilmenite i.e. hematite (Fe2O3), TiO2 anatase, TiO2 rutile, and inorganic salt. The leaching of the roasted ilmenite has been done by sulphuric acid solution (6 M) to gain the titanyl sulphate solution. Separation of iron impurities of TiO2 gel from titanyl sulphate (TiOSO4) solution was conducted by complexation method using EDTA as a complexation agent. The characteristic of TiO2 obtained using XRD showed that TiO2 is anatase type and the percentage of TiO2 using XRF showed that TiO2 content of 86,03%.

  16. 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)

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

    Braulio, Walace S.; Ladeira, Ana C.Q.

    2011-01-01

    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 3 O 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 -1 . The recovery of the uranium from the liquor is under investigation by ionic exchange. (author)

  18. Winter cover crops as a best management practice for reducing nitrogen leaching

    Ritter, W. F.; Scarborough, R. W.; Chirnside, A. E. M.

    1998-10-01

    The role of rye as a winter cover crop to reduce nitrate leaching was investigated over a three-year period on a loamy sand soil. A cover crop was planted after corn in the early fall and killed in late March or early April the following spring. No-tillage and conventional tillage systems were compared on large plots with irrigated corn. A replicated randomized block design experiment was conducted on small plots to evaluate a rye cover crop under no-tillage and conventional tillage and with commercial fertilizer, poultry manure and composted poultry manure as nitrogen fertilizer sources. Nitrogen uptake by the cover crop along with nitrate concentrations in groundwater and the soil profile (0-150 cm) were measured on the large plots. Soil nitrate concentrations and nitrogen uptake by the cover crop were measured on the small plots. There was no significant difference in nitrate concentrations in the groundwater or soil profile with and without a cover crop in either no-tillage or conventional tillage. Annual amounts of nitrate-N leached to the water-table varied from 136.0 to 190.1 kg/ha in 1989 and from 82.4 to 116.2 kg/ha in 1991. Nitrate leaching rates were somewhat lower with a cover crop in 1989, but not in 1990. There was no statistically significant difference in corn grain yields between the cover crop and non-cover crop treatments. The planting date and adequate rainfall are very important in maximizing nitrogen uptake in the fall with a rye cover crop. On the Delmarva Peninsula, the cover crop should probably be planted by October 1 to maximize nitrogen uptake rates in the fall. On loamy sand soils, rye winter cover crops cannot be counted on as a best management practice for reducing nitrate leaching in the Mid-Atlantic states.

  19. Kinetics of acid leaching of ilmenite decomposed by KOH part 1: decomposition by KOH and leaching by HCl

    Nayl, A.A; Aly, H.F.

    2010-01-01

    Decomposition of ilmenite by KOH solutions, to convert titanium to potassium titanate, was first studied . This was followed by leaching titanium from the ilmenite paste using HCl solutions in the temperature range 50-150 degree C for different periods up to 3 hr. The significant factors affecting the leaching process were studied. The experimental data of the decomposition rate of ilmenite by KOH and of the formed KOH paste by HCl under the relevant operating variables were interpreted with the shrinking core model under chemically controlled process. The apparent activation energy for leaching of titanium in both cases bas been evaluated and discussed.

  20. Reduction of inorganics from macroalgae Laminaria digitata and spent mushroom compost (SMC) by acid leaching and selective hydrothermal liquefaction

    Toor, Saqib Sohail; Jasiunas, Lukas; Xu, Chunbao (Charles)

    2018-01-01

    Hydrothermal liquefaction (HTL) is a promising route for producing bio-crude from various biomass feedstocks. However, high content of inorganic constituents in biomass like macroalgae Laminaria digitata and spent mushroom compost (SMC) affect the conversion process and the resulting fuel products....... This research studied the effects of different acid leaching treatments on such feedstocks, subsequent HTL, and bio-crude properties. Leaching treatments were performed using five different agents: deionized water, acetic acid, citric acid, sulfuric acid, and hydrochloric acid. Performance of leaching...... was evaluated by analyzing both leached biomass and HTL products by elemental analysis, ash content, inductively coupled plasma (ICP) analysis, and X-ray diffraction (XRD) analysis. Catalytic and non-catalytic HTL of both feedstocks before and after treatment were performed in a 10-mL microreactor at 400 °C...

  1. 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.

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

    Huang Chongyuan; Meng Jin; Li Weicai

    2003-01-01

    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/m 3 , the distance of the desalination flow 12-13 m, current efficiency 80%, and the throughput of the twin membrane 0.22-0.24 m 3 /(m 2 ·d)

  3. An efficient method combining thermal annealing and acid leaching ...

    This work investigates the photothermal treatment of silica sand to reduce impurities to a low level suitable for the ... duction of low cost SG-Si is the use of silica with high purity. ..... Farmer A D, Collings A F and Jameson G J 2000 Ultrason.

  4. Anti-reflection coatings applied by acid leaching process

    Pastirik, E.

    1980-01-01

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

  5. Acid-curing and ferric-trickle leaching effluent used in closed circuit uranium extractive process

    Jin Suoqing; Xiang Qinfang; Guo Jianzheng; Lu Guizhu; Su Yanru

    1998-01-01

    The new uranium ore process consists of crushing ore, mixing crushed ore with strong acid in rotating drums and curing the mixture in piles, trickle-leaching the ore beds with ferric solution, extracting uranium from pregnant solution with tertiary amine, precipitating product and disposing residue tailings. All the process effluent is used in closed circuit. There will be no process water to be discharged in the flowsheet except the tailings carrying off 15% water because during leaching moisture content of the ore rises to 15%. Tailings produced by the process are moist and friable, and can be disposed of on a pile or returned to the mine. Main technical parameters of the process: (a) water consumption is 0.2∼0.3 m 3 /t ore, electric power consumption is 20∼30 kW·h/t ore; (b) ore crushing up to -5∼-7 mm, leaching period is 12∼45 d, U content of residue is 0.01%∼0.02%, producing pregnant solution is 0.3∼0.5 m 3 /t ore, which is 1/5∼1/8 that of conventional agitation leaching process; (c) organic agent consumption is 1/5∼1/8 that of the conventional agitation process. All the research results above are tested by the pilot-plant test and industrial test. The new process has been applied to recovery of uranium in the mine located at northeast of China

  6. Leaching Characteristics of Calcium and Strontium from Phosphogypsum Under Acid Rain.

    Wang, Mei; Luo, Houqiao; Chen, Yong; Yang, Jinyan

    2018-02-01

    Phosphogypsum (PG) stored close to phosphorus chemical plants has caused worldwide environmental problems. Column leaching experiments were conducted to evaluate Ca and Sr leaching from PG under simulated acid rain at pH levels typical for rain in the study region (Shifang, China). High concentrations of Ca and Sr in leachates in the first five leaching events could pollute the soil and groundwater around the PG. Leachates pH was lower than and had no correlation with simulated rain pH. No correlations between simulated rain pH and cumulative Ca and Sr content in leachates were noted. Around 2.0%-2.2% of Ca and 0.5%-0.6% of Sr were leached out from PG by the simulated summer rainfall in Shifang. Electrical conductivity values, Ca and Sr concentrations at bottom sections of PG columns were higher than those of top sections, while pH values showed a reverse trend. More precautions should be taken to protect the environment around PG stacks.

  7. Investigation of the possibility of copper recovery from the flotation tailings by acid leaching.

    Antonijević, M M; Dimitrijević, M D; Stevanović, Z O; Serbula, S M; Bogdanovic, G D

    2008-10-01

    The flotation tailings pond of the Bor Copper Mine poses a great ecological problem not only for the town of Bor but also for the surrounding soils and watercourses. Since the old flotation tailings contain about 0.2% of copper on the average, we investigated their leaching with sulphuric acid in the absence and presence of an oxidant. The aim was to determine the leaching kinetics of copper and iron as affected by various factors such as: the pH value of the leach solution, stirring speed, pulp density, particle size, concentration of ferric ions, temperature and time for leaching. The average copper and iron recovery obtained was from 60% to 70% and from 2% to 3%, respectively. These results indicate that the old flotation tailings pond represents an important source of secondary raw material for the extraction of copper and that it should be valorized rather than land reclamation. At the end of the paper, a mechanism of dissolution of copper and iron minerals from the tailings was described.

  8. Alternative leaching processes for uranium ores

    Ring, R.J.

    1979-01-01

    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

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

    Alafara A. Baba

    2014-07-01

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

  10. Controlled Drainage As Measure to Reduce Nitrate Leaching in a Wheat Cropping System

    Børgesen, Christen Duus; Hvid, Søren Kolind; Thomsen, Ingrid Kaag

    2013-01-01

    for the growing crop, and nutrient exports are reduced. CD has been shown to diminish leaching losses of soluble nutrients. So far CD has only been tested for spring sown crops but widespread implementation on drained clayey soils would rely on its adaption to winter cereal production systems. A new project on CD...... applied at four winter cropped fields in Denmark investigates how effects of anaerobic conditions created by CD will affect chemical/biological processes in the submerged soil, root growth, crop production, and nutrient losses. Nitrification is expected to be retarded by wet soils during winter...

  11. 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. Copyright © 2015 Elsevier B.V. All rights reserved.

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

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

    2016-01-01

    Highlights: • U leaching from a low-grade Si-rich ore studied in H_2SO_4 medium with (MW) irradiation. • MW heating is more efficient in terms of U recovery, kinetics and purity of liquor. • U leachability of 84% obtained in 90 min at 95 °C with 0.38 M H_2SO_4 at 450 mVwith MW heating • Conventional conductive heating gave about 74% leachability with less purity liquor. • U leaching was found follow product layer diffusion as controlling mechanism. - Abstract: 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 (0.12–0.50 M), redox potential (400–500 mV), particle size (600–300 μm) 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.

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

    Madakkaruppan, V. [Atomic Minerals Directorate for Exploration and Research, Begumpet, Hyderabad 500016 (India); Pius, Anitha, E-mail: dranithapius@gmail.com [Department of Chemistry, Gandhigram Rural Institute, Gandhigram, Dindigul District, Tamil Nadu 624302 (India); Sreenivas, T.; Giri, Nitai [Mineral Processing Division, Bhabha Atomic Research Center, AMD Complex, Begumpet, Hyderabad 500016 (India); Sarbajna, Chanchal [Atomic Minerals Directorate for Exploration and Research, Begumpet, Hyderabad 500016 (India)

    2016-08-05

    Highlights: • U leaching from a low-grade Si-rich ore studied in H{sub 2}SO{sub 4} medium with (MW) irradiation. • MW heating is more efficient in terms of U recovery, kinetics and purity of liquor. • U leachability of 84% obtained in 90 min at 95 °C with 0.38 M H{sub 2}SO{sub 4} at 450 mVwith MW heating • Conventional conductive heating gave about 74% leachability with less purity liquor. • U leaching was found follow product layer diffusion as controlling mechanism. - Abstract: 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 (0.12–0.50 M), redox potential (400–500 mV), particle size (600–300 μm) 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.

  14. Recovery of tungsten from wolframite from the Igarape Manteiga mine (Rondonia - Brazil) via acidic leaching

    Paulino, Jessica Frontino; Afonso, Julio Carlos; Mantovano, Jose Luiz; Vianna, Claudio Augusto; Cunha, Jose Waldemar Silva Dias da

    2012-01-01

    We report results of the efficiency of tungsten extraction from wolframite concentrate (containing 61.5 wt % WO 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 3 content (90 wt %). This solid was dissolved in concentrated NH 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)

  15. Leaching variations of heavy metals in chelator-assisted phytoextraction by Zea mays L. exposed to acid rainfall.

    Lu, Yayin; Luo, Dinggui; Liu, Lirong; Tan, Zicong; Lai, An; Liu, Guowei; Li, Junhui; Long, Jianyou; Huang, Xuexia; Chen, Yongheng

    2017-11-01

    Chelant-enhanced phytoextraction method has been put forward as an effective soil remediation method, whereas the heavy metal leaching could not be ignored. In this study, a cropping-leaching experiment, using soil columns, was applied to study the metal leaching variations during assisted phytoextraction of Cd- and Pb-polluted soils, using seedlings of Zea mays, applying three different chelators (EDTA, EDDS, and rhamnolipid), and artificial rainfall (acid rainfall or normal rainfall). It showed that artificial rainfall, especially artificial acid rain, after chelator application led to the increase of heavy metals in the leaching solution. EDTA increased both Cd and Pb concentrations in the leaching solution, obviously, whereas EDDS and rhamnolipid increased Cd concentration but not Pb. The amount of Cd and Pb decreased as the leaching solution increased, the patterns as well matched LRMs (linear regression models), with R-square (R 2 ) higher than 90 and 82% for Cd and Pb, respectively. The maximum cumulative Cd and Pb in the leaching solutions were 18.44 and 16.68%, respectively, which was amended by EDTA and acid rainwater (pH 4.5), and followed by EDDS (pH 4.5), EDDS (pH 6.5), rhamnolipid (0.5 g kg -1 soil, pH 4.5), and rhamnolipid (pH 6.5).

  16. 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%.

  17. Spatial analyses of cost efficient measures to reduce N-leaching

    Jacobsen, Brian H.; Abildtrup, Jens; Ørum, Jens Erik

    (WFD). The analysis shows that the geographical position of the measures are very important in order to achieve the expected nutrient reduction. The current income varies a lot in the River basin and this might influence the choice of cost effective measures to reduce nutrient load. Furthermore a close......The Nitrate Directive has only been implemented satisfactorily in a few EU countries. The Commission have accepted the Danish implementation of the directive based on the Plan for the Aquatic Environment II. The costs of this plan has been calculated to 70 million € or 2,0 € per kg N in reduced...... leaching. The farmers have paid 60% of the costs. The paper then describes an example of a regional analysis covering the River Basin of Ringkøbing Fjord in Denmark, which indicates the type of calculations needed to find the measures and costs in order to comply with parts of the Water Framework Directive...

  18. Solvent-extraction and purification of uranium(VI) and molybdenum(VI) by tertiary amines from acid leach solutions

    La Gamma, Ana M.G.; Becquart, Elena T.; Chocron, Mauricio

    2008-01-01

    Considering international interest in the yellow-cake price, Argentina is seeking to exploit new uranium ore bodies and processing plants. A study of similar plants would suggest that solvent- extraction with Alamine 336 is considered the best method for the purification and concentration of uranium present in leaching solutions. In order to study the purification of these leach liquors, solvent-extraction tests under different conditions were performed with simulated solutions which containing molybdenum and molybdenum-uranium mixtures. Preliminary extraction tests carried out on mill acid-leaching liquors are also presented. (authors)

  19. Molybdenum isotope fractionation during acid leaching of a granitic uranium ore

    Migeon, Valérie; Bourdon, Bernard; Pili, Eric; Fitoussi, Caroline

    2018-06-01

    As an attempt to prevent illicit trafficking of nuclear materials, it is critical to identify the origin and transformation of uranium materials from the nuclear fuel cycle based on chemical and isotope tracers. The potential of molybdenum (Mo) isotopes as tracers is considered in this study. We focused on leaching, the first industrial process used to release uranium from ores, which is also known to extract Mo depending on chemical conditions. Batch experiments were performed in the laboratory with pH ranging from 0.3 to 5.5 in sulfuric acid. In order to span a large range in uranium and molybdenum yields, oxidizers such as nitric acid, hydrogen peroxide and manganese dioxide were also added. An enrichment in heavy Mo isotopes is produced in the solution during leaching of a granitic uranium ore, when Mo recovery is not quantitative. At least two Mo reservoirs were identified in the ore: ∼40% as Mo oxides soluble in water or sulfuric acid, and ∼40% of Mo hosted in sulfides soluble in nitric acid or hydrogen peroxide. At pH > 1.8, adsorption and/or precipitation processes induce a decrease in Mo yields with time correlated with large Mo isotope fractionations. Quantitative models were used to evaluate the relative importance of the processes involved in Mo isotope fractionation: dissolution, adsorption, desorption, precipitation, polymerization and depolymerization. Model best fits are obtained when combining the effects of dissolution/precipitation, and adsorption/desorption onto secondary minerals. These processes are inferred to produce an equilibrium isotope fractionation, with an enrichment in heavy Mo isotopes in the liquid phase and in light isotopes in the solid phase. Quantification of Mo isotope fractionation resulting from uranium leaching is thus a promising tool to trace the origin and transformation of nuclear materials. Our observations of Mo leaching are also consistent with observations of natural Mo isotope fractionation taking place during

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

    Hu Jun; Wang Zhaoguo; Chi Renqing; Niu Xuejun

    1994-01-01

    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

  1. Antimony leaching release from brake pads: Effect of pH, temperature and organic acids.

    Hu, Xingyun; He, Mengchang; Li, Sisi

    2015-03-01

    Metals from automotive brake pads pollute water, soils and the ambient air. The environmental effect on water of antimony (Sb) contained in brake pads has been largely untested. The content of Sb in one abandoned brake pad reached up to 1.62×10(4) mg/kg. Effects of initial pH, temperature and four organic acids (acetic acid, oxalic acid, citric acid and humic acid) on Sb release from brake pads were studied using batch reactors. Approximately 30% (97 mg/L) of the total Sb contained in the brake pads was released in alkaline aqueous solution and at higher temperature after 30 days of leaching. The organic acids tested restrained Sb release, especially acetic acid and oxalic acid. The pH-dependent concentration change of Sb in aqueous solution was best fitted by a logarithmic function. In addition, Sb contained in topsoil from land where brake pads were discarded (average 9×10(3) mg/kg) was 3000 times that in uncontaminated soils (2.7±1 mg/kg) in the same areas. Because potentially high amounts of Sb may be released from brake pads, it is important that producers and environmental authorities take precautions. Copyright © 2015. Published by Elsevier B.V.

  2. Sustainable recovery of valuable metals from spent lithium-ion batteries using DL-malic acid: Leaching and kinetics aspect.

    Sun, Conghao; Xu, Liping; Chen, Xiangping; Qiu, Tianyun; Zhou, Tao

    2018-02-01

    An eco-friendly and benign process has been investigated for the dissolution of Li, Co, Ni, and Mn from the cathode materials of spent LiNi 1/3 Co 1/3 Mn 1/3 O 2 batteries, using DL-malic acid as the leaching agent in this study. The leaching efficiencies of Li, Co, Ni, and Mn can reach about 98.9%, 94.3%, 95.1%, and 96.4%, respectively, under the leaching conditions of DL-malic acid concentration of 1.2 M, hydrogen peroxide content of 1.5 vol.%, solid-to-liquid ratio of 40 g l -1 , leaching temperature of 80°C, and leaching time of 30 min. In addition, the leaching kinetic was investigated based on the shrinking model and the results reveal that the leaching reaction is controlled by chemical reactions within 10 min with activation energies (Ea) of 21.3 kJ·mol -1 , 30.4 kJ·mol -1 , 27.9 kJ·mol -1 , and 26.2 kJ·mol -1 for Li, Co, Ni, and Mn, respectively. Diffusion process becomes the controlled step with a prolonged leaching time from 15 to 30 min, and the activation energies (Ea) are 20.2 kJ·mol -1 , 28.9 kJ·mol -1 , 26.3 kJ·mol -1 , and 25.0 kJ·mol -1 for Li, Co, Ni, and Mn, respectively. This hydrometallurgical route was found to be effective and environmentally friendly for leaching metals from spent lithium batteries.

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

    Tostar, Sandra; Stenvall, Erik; Boldizar, Antal; Foreman, Mark R St J

    2013-06-01

    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 (0.5M) 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. Copyright © 2013 Elsevier Ltd. All rights reserved.

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

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

    2014-04-30

    Cement stabilization is a practical approach to remediate soils contaminated with high levels of lead. However, the potential for leaching of lead out of these stabilized soils under variable acid rain pH conditions is a major environmental concern. This study investigates the effects of acid rain on the leaching characteristics of cement stabilized lead contaminated soil under different pH conditions. Clean kaolin clay and the same soil spiked with 2% lead contamination are stabilized with cement contents of 12 and 18% and then cured for 28 days. The soil samples are then subjected to a series of accelerated leaching tests (or semi-dynamic leaching tests) using a simulated acid rain leachant prepared at pH 2.0, 4.0 or 7.0. The results show that the strongly acidic leachant (pH ∼2.0) significantly altered the leaching behavior of lead as well as calcium present in the soil. However, the differences in the leaching behavior of the soil when the leachant was mildly acidic (pH ∼4.0) and neutral (pH ∼7.0) prove to be minor. In addition, it is observed that the lead contamination and cement content levels can have a considerable impact on the leaching behavior of the soils. Overall, the leachability of lead and calcium is attributed to the stability of the hydration products and their consequent influence on the soil buffering capacity and structure. Copyright © 2014 Elsevier B.V. All rights reserved.

  5. Leaching kinetics of neodymium in sulfuric acid of rare earth elements (REE) slag concentrated by pyrometallurgy from magnetite ore

    Yoon, Ho-Sung; Kim, Chul-Joo; Chung, Kyung Woo; Lee, Jin-Young; Shin, Shun Myung; Lee, Su-Jeong; Joe, A-Ram; Lee, Se-Il; Yoo, Seung-Joon

    2014-01-01

    We studied the leaching kinetics of recovering neodymium in sulfuric acid from the rare earth elements (REE) slag concentrated by smelting reduction from a magnetite ore containing monazite. The leaching kinetics on neodymium was conducted at a reactant concentration of 1.5 g REE slag per L of 0.3M H 2 SO 4 , agitation of 750 rpm and temperature ranging from 30 to 80 .deg. C. Neodymium oxide included in the REE slag was completely converted into neodymium sulfate phase (Nd 2 (SO 4 ) 3 ) in H 2 SO 4 after the leaching of 5 h, 80 .deg. C. As a result, the leaching mechanism was determined in a two-stage model based on the shrinking core model with spherical particles. The first step was determined by chemical reaction, and the second step was determined by ash layer diffusion because the leaching of REEs by the first chemical reaction increases the formation of the ash layer affecting as a resistance against the leaching. By using the Arrhenius expression, the apparent activation energy of the first chemical reaction step was found to be 9 kJmol -1 . After the first chemical reaction, leaching reaction rate was determined by the ash layer diffusion. The apparent activation energy of ash layer diffusion was found to be 32 kJmol -1

  6. Leaching kinetics of neodymium in sulfuric acid of rare earth elements (REE) slag concentrated by pyrometallurgy from magnetite ore

    Yoon, Ho-Sung; Kim, Chul-Joo; Chung, Kyung Woo; Lee, Jin-Young; Shin, Shun Myung [Korea Institute of Geoscience and Mineral Resources (KIGAM), Daejeon (Korea, Republic of); Lee, Su-Jeong; Joe, A-Ram; Lee, Se-Il; Yoo, Seung-Joon [Seonam University, Asan (Korea, Republic of)

    2014-10-15

    We studied the leaching kinetics of recovering neodymium in sulfuric acid from the rare earth elements (REE) slag concentrated by smelting reduction from a magnetite ore containing monazite. The leaching kinetics on neodymium was conducted at a reactant concentration of 1.5 g REE slag per L of 0.3M H{sub 2}SO{sub 4}, agitation of 750 rpm and temperature ranging from 30 to 80 .deg. C. Neodymium oxide included in the REE slag was completely converted into neodymium sulfate phase (Nd{sub 2}(SO{sub 4}){sub 3}) in H{sub 2}SO{sub 4} after the leaching of 5 h, 80 .deg. C. As a result, the leaching mechanism was determined in a two-stage model based on the shrinking core model with spherical particles. The first step was determined by chemical reaction, and the second step was determined by ash layer diffusion because the leaching of REEs by the first chemical reaction increases the formation of the ash layer affecting as a resistance against the leaching. By using the Arrhenius expression, the apparent activation energy of the first chemical reaction step was found to be 9 kJmol{sup -1}. After the first chemical reaction, leaching reaction rate was determined by the ash layer diffusion. The apparent activation energy of ash layer diffusion was found to be 32 kJmol{sup -1}.

  7. 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.)

  8. 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. Copyright © 2015 Elsevier Ltd. All rights reserved.

  9. Comparative leaching of six toxic metals from raw and chemically stabilized MSWI fly ash using citric acid.

    Wang, Huawei; Fan, Xinxiu; Wang, Ya-Nan; Li, Weihua; Sun, Yingjie; Zhan, Meili; Wu, Guizhi

    2018-02-15

    The leaching behavior of six typical toxic metals (Pb, Zn, Cr, Cd, Cu and Ni) from raw and chemically stabilized (phosphate and chelating agent) municipal solid waste incineration (MSWI) fly ash were investigated using citric acid. Leaching tests indicated that phosphate stabilization can effectively decrease the leaching of Zn, Cd and Cr; whereas chelating agent stabilization shows a strong ability to lower the release of Pb, Cd and Cu, but instead increases the solubility of Zn and Cr at low pH conditions. Sequential extraction results suggested that the leaching of Pb, Zn and Cd in both the stabilized MSWI fly ash samples led to the decrease in Fe/Mn oxide fraction and the increase in exchangeable and carbonate fractions. The leaching of Cr was due to the decrease in exchangeable, carbonate and Fe/Mn oxide fractions in phosphate-stabilized and chelating agent-stabilized MSWI fly ash. The leaching of Cu in both stabilized MSWI fly ash was greatly ascribed to the decrease in Fe/Mn oxide and oxidisable fractions. Moreover, predicted curves by geochemical model indicated that both stabilized MSWI fly ash have the risk of releasing toxic metals under strong acid environment. Copyright © 2017 Elsevier Ltd. All rights reserved.

  10. Reducing nitrate leaching to groundwater in an intensive dairy farming system

    Verloop, J.; Boumans, L.J.M.; Keulen, van H.; Oenema, J.; Hilhorst, G.J.; Aarts, H.F.M.; Sebek, L.B.J.

    2006-01-01

    Dairy farming is one of the main contributors to nitrate leaching to groundwater, particularly on soils that are susceptible to leaching, such as light well-drained sandy soils. In the Netherlands, as in many other European countries, these soils are predominantly used for dairy farming. A prototype

  11. 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

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

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

    2010-06-15

    An ultrasonically enhanced two-stage acid leaching process on extracting and recovering multiple heavy metals from actual electroplating sludge was studied in lab tests. It provided an effective technique for separation of valuable metals (Cu, Ni and Zn) from less valuable metals (Fe and Cr) in electroplating sludge. The efficiency of the process had been measured with the leaching efficiencies and recovery rates of the metals. Enhanced by ultrasonic power, the first-stage acid leaching demonstrated leaching rates of 96.72%, 97.77%, 98.00%, 53.03%, and 0.44% for Cu, Ni, Zn, Cr, and Fe respectively, effectively separated half of Cr and almost all of Fe from mixed metals. The subsequent second-stage leaching achieved leaching rates of 75.03%, 81.05%, 81.39%, 1.02%, and 0% for Cu, Ni, Zn, Cr, and Fe that further separated Cu, Ni, and Zn from mixed metals. With the stabilized two-stage ultrasonically enhanced leaching, the resulting over all recovery rates of Cu, Ni, Zn, Cr and Fe from electroplating sludge could be achieved at 97.42%, 98.46%, 98.63%, 98.32% and 100% respectively, with Cr and Fe in solids and the rest of the metals in an aqueous solution discharged from the leaching system. The process performance parameters studied were pH, ultrasonic power, and contact time. The results were also confirmed in an industrial pilot-scale test, and same high metal recoveries were performed. Copyright 2010 Elsevier B.V. All rights reserved.

  13. Acid-Gangue Interactions in Heap Leach Operations: A Review of the Role of Mineralogy for Predicting Ore Behaviour

    Deshenthree Chetty

    2018-01-01

    Full Text Available Heap leaching accounts for a fifth of global copper production, sourced primarily from porphyry ores, yet metal recoveries are often not optimal. Gangue, and its interaction with acid, plays an important role in such processes. Thus, a proper understanding of gangue minerals present in the ore, their textural relationships relative to particle size distribution, reactivity with acid under different conditions, and relationship to lithotypes and geological alteration in the orebody, is necessary to predict ore behaviour in the comminution, agglomeration, curing and heap leach unit operations. Mineralogical tools available for characterisation are routine X-ray diffraction, optical microscopy, automated scanning electron microscopy, and electron probe microanalysis, accompanied by more recent advancements in hyperspectral infrared imaging and X-ray computed tomography. Integrated use of these techniques allows mineral abundance, textural relationships and mineral chemistry to be addressed over the range of particle and agglomerate sizes. Additionally, diagnostic leach results can be better interpreted when calibrated against robust mineralogical data. The linkage of ore attributes, metallurgical behaviour and their distribution in the orebody forms an integral part of a geometallurgical approach to predicting, and addressing, changes during the heap leaching process. Further investigation should address the fundamentals of gangue reaction with strong acid, and concomitant structural breakdown during curing and agglomeration processes, and how this differs from gangue-acid reactivity under weaker acid conditions, combined with temperature and fluid flow effects of heap leaching. Pre-and post- characterisation is necessary to understand and quantify the effects of variables for gangue-acid reactivity in these various operations. The characterisation outcomes should lead to a refinement of the hierarchy of gangue mineral reactivity under different

  14. Influence of soil and climate heterogeneity on the performance of economic instruments for reducing nitrate leaching from agriculture.

    Peña-Haro, Salvador; García-Prats, Alberto; Pulido-Velazquez, Manuel

    2014-11-15

    Economic instruments can be used to control groundwater nitrate pollution due to the intensive use of fertilizers in agriculture. In order to test their efficiency on the reduction of nitrate leaching, we propose an approach based on the combined use of production and pollution functions to derive the impacts on the expected farmer response of these instruments. Some of the most important factors influencing nitrate leaching and crop yield are the type of soil and the climatic conditions. Crop yield and nitrate leaching responses to different soil and climatic conditions were classified by means of a cluster analysis, and crops located in different areas but with similar response were grouped for the analysis. We use a spatial economic optimization model to evaluate the potential of taxes on nitrogen fertilizers, water prices, and taxes on nitrate emissions to reduce nitrate pollution, as well as their economic impact in terms of social welfare and farmers' net benefits. The method was applied to the Mancha Oriental System (MOS) in Spain, a large area with different soil types and climatic conditions. We divided the study area into zones of homogeneous crop production and nitrate leaching properties. Results show spatially different responses of crop growth and nitrate leaching, proving how the cost-effectiveness of pollution control instruments is contingent upon the spatial heterogeneities of the problem. Copyright © 2014 Elsevier B.V. All rights reserved.

  15. Reduced rates of controlled-release fertilizer lower potential nitrogen leaching from a Wisconsin bare-root tree nursery

    Ryosuke Fujinuma; Nick J. Balster; Hyung-Kyung. Lee

    2011-01-01

    Controlled-release fertilizer (CRF) typically increases nitrogen (N) fertilizer uptake and lowers N lost from the rooting zone via leaching. However, questions remain as to whether lower rates of CRF could further increase this efficiency, especially in sandy bare-root nurseries in Wisconsin. We hypothesized that: 1) a reduced CRF application at 60 percent of the...

  16. Leaching and accumulation of trace elements in sulfate reducing granular sludge under concomitant thermophilic and low pH conditions

    Gonzalez-Gil, G.; Lopes, S.I.C.; Saikaly, P.E.; Lens, P.N.L.

    2012-01-01

    The leaching and/or accumulation of trace elements in sulfate reducing granular sludge systems was investigated. Two thermophilic up-flow anaerobic sludge bed (UASB) reactors operated at pH 5 were fed with sucrose (4 g COD l(reactor)(-1) d(-1)) and sulfate at different COD/SO42- ratios. During the

  17. Method of continuous pressure leaching of ores

    Fiala, P.; Baloun, S.; Polansky, M.

    1987-01-01

    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.)

  18. EDTA and HCl leaching of calcareous and acidic soils polluted with potentially toxic metals: remediation efficiency and soil impact.

    Udovic, Metka; Lestan, Domen

    2012-07-01

    The environmental risk of potentially toxic metals (PTMs) in soil can be diminished by their removal. Among the available remediation techniques, soil leaching with various solutions is one of the most effective but data about the impact on soil chemical and biological properties are still scarce. We studied the effect of two common leaching agents, hydrochloric acid (HCl) and a chelating agent (EDTA) on Pb, Zn, Cd removal and accessibility and on physico-chemical and biological properties in one calcareous, pH neutral soil and one non-calcareous acidic soil. EDTA was a more efficient leachant compared to HCl: up to 133-times lower chelant concentration was needed for the same percentage (35%) of Pb removal. EDTA and HCl concentrations with similar PTM removal efficiency decreased PTM accessibility in both soils but had different impacts on soil properties. As expected, HCl significantly dissolved carbonates from calcareous soil, while EDTA leaching increased the pH of the acidic soil. Enzyme activity assays showed that leaching with HCl had a distinctly negative impact on soil microbial and enzyme activity, while leaching with EDTA had less impact. Our results emphasize the importance of considering the ecological impact of remediation processes on soil in addition to the capacity for PTM removal. Copyright © 2012 Elsevier Ltd. All rights reserved.

  19. Main ways and suitable technologies of improving economic benefits for uranium ore heap leaching in China (the end)

    Guan Zibin

    2001-01-01

    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-currying 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

  20. Research on the effect of alkali roasting of copper dross on leaching rate of indium

    Dafang, Liu; Fan, Xingxiang; Shi, Yifeng; Yang, Kunbin

    2017-11-01

    The byproduct copper dross produced during refining crude lead was characterized by X-ray diffraction (XRD), scanning electron microscope (SEM) and fluorescence spectrometer (XRF), which showed that copper dross mainly contained lead, copper, zinc, arsenic, antimony, bismuth, sulfur and a small amount of indium and silver etc. The mineralogical phase change of oxidation roasting of copper dross by adding sodium hydroxide was analyzed with the help of XRD and SEM. The effects of water leaching, ratio of sodium hydroxide, roasting time, and roasting temperature on leaching rate of indium were investigated mainly. The experimental results showed that phase of lead metal and sulfides of lead, copper and zinc disappeared after oxidation roasting of copper dross by adding sodium hydroxide, new phase of oxides of lead, copper, zinc and sodium salt of arsenic and antimony appeared. Water leaching could remove arsenic, and acid leaching residue obtained was then leached with acid. The leaching rate of indium was higher 6.98% compared with alkali roasting of copper dross-acid leaching. It showed that removing arsenic by water leaching and acid leaching could increase the leaching rate of indium and be beneficial to reducing subsequent acid consumption of extracting indium by acid leaching. The roasting temperature had a significant effect on the leaching rate of indium, and leaching rate of indium increased with the rise of roasting temperature. When roasting temperature ranged from 450°C to 600°C, leaching rate of indium increased significantly with the rise of roasting temperature. When roasting temperature rose from 450°C to 600°C, leaching rate of indium increased by 60.29%. The amount of sodium hydroxide had an significant effect on the leaching rate of indium, and the leaching of indium increased with the increase of the amount of sodium hydroxide, and the leaching rate of indium was obviously higher than that of copper dross blank roasting and acid leaching.

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

    Sara Asselin

    2014-01-01

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

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

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

    2005-07-01

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

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

    1998-07-01

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

  4. A procedure for oxidation during the acid leaching of non-ferrous ores, particularly uranium ores

    Zubcek, L.; Baloun, S.; Martinek, K.; Vebr, Z.; Krepelka, J.; Lasica, S.

    1989-01-01

    It is suggested that dust from the production of ferroalloys of manganese, particularly ferrosilicomanganese and ferromanganese, can be conveniently used for oxidation during the acid leaching of non-ferrous ores, particularly uranium ores. This dust contains 30 to 40% oxides of manganese, about one-half of this is MnO 2 . Iron in the dust is present in the trivalent form, and the dust is pefectly dry. The conventional grinding of oxidants for the ore processing is eliminated, the dust being available in particle size below 0.2 mm. The dust is added in amounts of 5 to 100 kg per ton of the ore, and the suspension is typically heated at 115 degC for 3.5 hr. (P.A.)

  5. 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

    content at the time of application and the level of the groundwater table relative to the drain depth was essential for whether solutes were detected in the drainage runoff. We present a leaching risk chart to illustrate the dependence of glyphosate, AMPA, and soil particle leaching based on precipitation......, and particles. Glyphosate and AMPA leaching were highly event driven, controlled by the time and intensity of the first precipitation event after glyphosate application. A high similarity in time-accumulated curves for drainage and leached pesticide masses suggests near-constant drainage and leaching rates...

  6. Investigation of Enhanced Leaching of Lithium from α-Spodumene Using Hydrofluoric and Sulfuric Acid

    Hui Guo

    2017-10-01

    Full Text Available An effective method using hydrofluoric and sulfuric acid was proposed to enhance the leaching of lithium from α-spodumene, without calcination that is subjected to 1000 °C for phase transformation. The thermodynamic feasibility of the reactions was firstly verified. Dissolution conditions were tested to maximize the leaching efficiency of lithium and with efficient utilization of hydrofluoric acid (HF served as evaluation criteria. The results showed that 96% of lithium could be transferred into lixivium with an ore/HF/H2SO4 ratio of 1:3:2 (g/mL/mL, at 100 °C for 3 h. Due to the fact that HF molecules were the main reaction form, the dissolution behaviors were theoretically represented and investigated by dissolution in HF/H2SO4. When combined with chemical elements analyses and characterizations, the results of the dissolution behaviors revealed that α-spodumene and albite were preferentially dissolved over quartz. Insoluble fluoroaluminates, such as AlF3, cryolite (Na3AlF6 and cryolithionite (Na3Li3Al2F12, were generated and might be further partially dissolved by H2SO4. Fluorosilicates, such as K2SiF6, Na2SiF6, or KNaSiF6, were also generated as a part of the insoluble residues. This work provides fundamental insight into the role of HF/H2SO4 played in the dissolution of α-spodumene, and sheds light on a novel and promising process to efficiently extract lithium.

  7. 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.

  8. 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

    2015-01-01

    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 2 O 4 ⋅2H 2 O and Li 2 CO 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. Extraction of uranium from coarse ore and acid-curing and ferric sulphate-trickle leaching process

    Jin Suoqing

    1994-01-01

    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

  10. Kinetic and Mechanism Study of Vanadium Acid Leaching from Black Shale Using Microwave Heating Method

    Wang, Jing-peng; Zhang, Yi-min; Huang, Jing; Liu, Tao

    2018-06-01

    The leaching kinetics of the vanadium leaching process were investigated by the comparison of microwave heating and conventional heating methods. Microwave heating with CaF2 had a synergistic effect and improved the vanadium leaching efficiency. In contrast to conventional heating leaching, microwave heating accelerated the vanadium leaching rate by approximately 1-3% and by approximately 15% when CaF2 was also used. The kinetics analysis showed that the calculated activation energy decreased in the microwave heating method in the presence and absence of CaF2. The control procedure of leaching also changed from a chemical reaction control step to a mixed chemical diffusion control step upon the addition of CaF2. Microwave heating was shown to be suitable for leaching systems with diffusion or mixed chemical diffusion control steps when the target mineral does not have a microwave absorbing ability.

  11. Kinetic and Mechanism Study of Vanadium Acid Leaching from Black Shale Using Microwave Heating Method

    Wang, Jing-peng; Zhang, Yi-min; Huang, Jing; Liu, Tao

    2018-04-01

    The leaching kinetics of the vanadium leaching process were investigated by the comparison of microwave heating and conventional heating methods. Microwave heating with CaF2 had a synergistic effect and improved the vanadium leaching efficiency. In contrast to conventional heating leaching, microwave heating accelerated the vanadium leaching rate by approximately 1-3% and by approximately 15% when CaF2 was also used. The kinetics analysis showed that the calculated activation energy decreased in the microwave heating method in the presence and absence of CaF2. The control procedure of leaching also changed from a chemical reaction control step to a mixed chemical diffusion control step upon the addition of CaF2. Microwave heating was shown to be suitable for leaching systems with diffusion or mixed chemical diffusion control steps when the target mineral does not have a microwave absorbing ability.

  12. Dynamic Characteristics and Model for Centralization Reaction of Acidic Tailings From Heap Leaching of Uranium Ore

    Ding Dexin; Liu Yulong; Li Guangyue; Wang Youtuan

    2010-01-01

    Centralization tests were carried out on acidic tailings from heap leaching of uranium ore by using CaO, NaOH and NH 4 OH. The variations of pH with time were measured for the three centralization systems and the dynamic models for the systems were set up by regressing the measured data. The centralization process consists of the fast reaction phase representing the reaction between the centralization agent and the acid on the surface of the tailing's particles and the slow diffusion-reaction phase representing the diffusion-reaction between the centralization agent and the acid within the tailing's particles. The non-linear coupling and feedback function model for the diffusion-reaction of the centralization agent can reflect the process and mode of the centralization reaction. There is a non-linear oscillation in the variation of pH within the centralization systems. The dynamic model for the tailing's centralization reaction can fit the pH variation within the centralization systems. (authors)

  13. Zero-valent iron nanoparticles in treatment of acid mine water from in situ uranium leaching.

    Klimkova, Stepanka; Cernik, Miroslav; Lacinova, Lenka; Filip, Jan; Jancik, Dalibor; Zboril, Radek

    2011-02-01

    Acid mine water from in situ chemical leaching of uranium (Straz pod Ralskem, Czech Republic) was treated in laboratory scale experiments by zero-valent iron nanoparticles (nZVI). For the first time, nZVI were applied for the treatment of the real acid water system containing the miscellaneous mixture of pollutants, where the various removal mechanisms occur simultaneously. Toxicity of the treated saline acid water is caused by major contaminants represented by aluminum and sulphates in a high concentration, as well as by microcontaminants like As, Be, Cd, Cr, Cu, Ni, U, V, and Zn. Laboratory batch experiments proved a significant decrease in concentrations of all the monitored pollutants due to an increase in pH and a decrease in oxidation-reduction potential related to an application of nZVI. The assumed mechanisms of contaminants removal include precipitation of cations in a lower oxidation state, precipitation caused by a simple pH increase and co-precipitation with the formed iron oxyhydroxides. The possibility to control the reaction kinetics through the nature of the surface stabilizing shell (polymer vs. FeO nanolayer) is discussed as an important practical aspect. Copyright © 2010 Elsevier Ltd. All rights reserved.

  14. Policy Incentives for Reducing Nitrate Leaching in Agricultural Lands: A Case Study of Irrigation and Drainage Dorudzan

    Sheikhzeinoddin, A.; Esmaeili, A.; Zibaei, M.

    2016-01-01

    Agricultural activities increasingly use water, fertilizers and pesticides, which may generate negative impacts on environment. Nowadays, nitrogen leaching from agricultural lands is a widespread global problem. Therefore, alternative land management practices such as nutrient management (rate, method and time of application), tillage operations (conservation and no-tillage), and irrigation management are routinely used to reduce non-point source pollution and improve water quality. In fact, a number of studies have illustrated the positive effects of best management practices on water and nutrient losses. The objective of this paper is to develop a bio-economic model and introducing the policy instrument for reducing nitrate from irrigation and drainage Dorudzan. We aim to identify ‘‘win–win’’ opportunities for improving farm profitability and reducing nitrate leaching.

  15. Acid leaching of oxide-sulphide copper ore prior the flotation: A way for an increased metal recovery

    Sokić Miroslav D.

    2015-01-01

    Full Text Available Copper mine "Cerovo"- East Serbia as well as the other ore bodies in its vicinity contain a significant amount of oxide copper minerals in their uper layers (>40%. Processing of such mixed ores by the existing concentration technologies leads to a substantial copper losses (<60%. Reduction of "oxide copper", by acid leaching prior the flotation concentration, can increase the overall copper efficiency up to more than 70% in the single-stage leaching, achieving an efficiency in the flotation concentration stage higher than 75%. Based on the performed experimental results the flow sheet for processing of the mixed oxide-sulphide copper ore is proposed.

  16. 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

  17. 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.

  18. Process optimization and leaching kinetics of zinc and manganese metals from zinc-carbon and alkaline spent batteries using citric acid reagent

    Yuliusman; Amiliana, R. A.; Wulandari, P. T.; Huda, M.; Kusumadewi, F. A.

    2018-03-01

    Zn-Carbon and Alkaline spent batteries contains heavy metals, such as zinc and manganese, which can causes environmental problem if not handled properly. Usually the recovery of these metals were done by leaching method using strong acid, but the use of strong acids as leaching reagents can be harmful to the environment. This paper concerns the recovery of Zn and Mn metals from Zn-C and alkaline spent batteries with leaching method using citric acid as the environmental friendly leaching reagent. The leaching conditions using citric acid were optimized and the leaching kinetics of Zn and Mn in citric acid solution was investigated. The leaching of 89.62% Zn and 63.26% Mn was achieved with 1.5 M citric acid, 90°C temperature, and 90 minutes stirring time. Kinetics data for the dissolution of Zn showed the best fit to chemical control shrinking core model, while the diffusion controlled model was suitable for the dissolution of Mn kinetics data. The activation energy of 6.12 and 1.73 kcal/mol was acquired for the leaching of Zn and Mn in the temperature range 60°C-90°C.

  19. Biochar amendment reduces paddy soil nitrogen leaching but increases net global warming potential in Ningxia irrigation, China.

    Wang, Yongsheng; Liu, Yansui; Liu, Ruliang; Zhang, Aiping; Yang, Shiqi; Liu, Hongyuan; Zhou, Yang; Yang, Zhengli

    2017-05-09

    The efficacy of biochar as an environmentally friendly agent for non-point source and climate change mitigation remains uncertain. Our goal was to test the impact of biochar amendment on paddy rice nitrogen (N) uptake, soil N leaching, and soil CH 4 and N 2 O fluxes in northwest China. Biochar was applied at four rates (0, 4.5, 9 and13.5 t ha -1 yr -1 ). Biochar amendment significantly increased rice N uptake, soil total N concentration and the abundance of soil ammonia-oxidizing archaea (AOA), but it significantly reduced the soil NO 3 - -N concentration and soil bulk density. Biochar significantly reduced NO 3 - -N and NH 4 + -N leaching. The C2 and C3 treatments significantly increased the soil CH 4 flux and reduced the soil N 2 O flux, leading to significantly increased net global warming potential (GWP). Soil NO 3 - -N rather than NH 4 + -N was the key integrator of the soil CH 4 and N 2 O fluxes. Our results indicate that a shift in abundance of the AOA community and increased rice N uptake are closely linked to the reduced soil NO 3 - -N concentration under biochar amendment. Furthermore, soil NO 3 - -N availability plays an important role in regulating soil inorganic N leaching and net GWP in rice paddies in northwest China.

  20. 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; Kim, Hyung-Seop; Cho, Jong-Tae; Kim, Ji-Hye; Lee, Eun-Ji; Lee, Se-Il; Yoo, Seung-Joon

    2015-01-01

    A leaching kinetics was conducted for the purpose of recovery of praseodymium in sulfuric acid (H 2 SO 4 ) from REE slag concentrated by the smelting reduction process in an arc furnace as a reactant. The concentration of H 2 SO 4 was fixed at an excess ratio under the condition of slurry density of 1.500 g slag/L, 0.3 mol H 2 SO 4 , and the effect of temperatures was investigated under the condition of 30 to 80 .deg. C. As a result, praseodymium oxide (Pr 6 O 1 1) existing in the slag was completely converted into praseodymium sulfate (Pr 2 (SO 4 ) 3 ·8H 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 -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

  1. 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.

  2. 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.

  3. Soil biota enhance agricultural sustainability by improving crop yield, nutrient uptake and reducing nitrogen leaching losses

    Bender, S.F.; van der Heijden, M.G.A.|info:eu-repo/dai/nl/240923901

    2015-01-01

    Efficient resource use is a key factor for sustainable production and a necessity for meeting future global food demands. However, the factors that control resource use efficiency in agro-ecosystems are only partly understood. We investigated the influence of soil biota on nutrient leaching,

  4. Composting and gypsum amendment of broiler litter to reduce nutrient leaching loss

    Relative to fresh broiler litter, little is known about the dynamics of composted litter derived-nutrient in the ecosystem. In this study, the potential leaching losses of nutrients from compost relative to fresh broiler litter along with flue gas desulfurization (FGD gypsum), as a nutrient immobil...

  5. Recovery of Vanadium from Magnetite Ore Using Direct Acid Leaching: Optimization of Parameters by Plackett-Burman and Response Surface Methodologies

    Nejad, Davood Ghoddocy; Khanchi, Ali Reza; Taghizadeh, Majid

    2018-06-01

    Recovery of vanadium from magnetite ore by direct acid leaching is discussed. The proposed process, which employs a mixture of nitric and sulfuric acids, avoids pyrometallurgical treatments since such treatment consumes a high amount of energy. To determine the optimum conditions of vanadium recovery, the leaching process is optimized through Plackett-Burman (P-B) design and response surface methodology (RSM). In this respect, temperature (80-95°C), liquid to solid ratio (L/S) (3-10 mL g-1), sulfuric acid concentration (3-6 M), nitric acid concentration (5-10 vol.%) and time (4-8 h) are considered as the independent variables. According to the P-B approach, temperature and acid concentrations are, respectively, the most effective parameters in the leaching process. These parameters are optimized using RSM to maximize recovery of vanadium by direct acid leaching. In this way, 86.7% of vanadium can be extracted from magnetic ore.

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

    Tariq, M.; Iqbal, M.M.; Shafiq, M.; Aziz, A.

    2014-01-01

    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)

  7. Catch crops as universal and effective method for reducing nitrogen leaching loss in spring cereal production: A meta-analysis.

    Valkama, Elena; Lemola, Riitta; Känkänen, Hannu; Turtola, Eila

    2016-04-01

    Sustainable farms produce adequate amounts of a high-quality product, protect their resources and are both environmentally friendly and economically profitable. Nitrogen (N) fertilization decisively influences the cereal yields as well as increases soil N balance (N input in fertilizer - N output in harvested yield), thereby leading to N losses to the environment. However, while N input reduction affects soil N balance, such approach would markedly reduce N leaching loss only in case of abnormally high N balances. As an alternative approach, the growing of catch crops aims to prevent nutrient leaching in autumn after harvest and during the following winter, but due to competition, catch crops may also reduce yields of the main crop. Although studies have explored the environmental effects of catch crops in cereal production in the Nordic countries (Denmark, Sweden, Finland and Norway) during the past 40 years, none has yet carried out a meta-analysis. We quantitatively summarized 35 studies on the effect of catch crops (non-legume and legume) undersown in spring cereals on N leaching loss or its risk as estimated by the content of soil nitrate N or its sum with ammonium in late autumn. The meta-analysis also included the grain yield and N content of spring cereals. To identify sources of variation, we studied the effects of soil texture and management (ploughing time, the amount of N applied, fertilizer type), as well as climatic (annual precipitation) and experimental conditions (duration of experiments, lysimeter vs. field experiments). Finally, we examined whether the results differed between the countries or over the decades. Compared to control groups with no catch crops, non-legume catch crops, mainly ryegrass species, reduced N leaching loss by 50% on average, and soil nitrate N or inorganic N by 35% in autumn. Italian ryegrass depleted soil N more effectively (by 60%) than did perennial ryegrass or Westerwolds ryegrass (by 25%). In contrast, legumes (white

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

    Das, Amrita; Yadav, Manoj; Chatterjee, Ankur; Singh, A.K.; Hubli, R.C.

    2012-01-01

    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

  9. Sorbent amendment as a remediation strategy to reduce PFAS mobility and leaching in a contaminated sandy soil from a Norwegian firefighting training facility.

    Hale, Sarah E; Arp, Hans Peter H; Slinde, Gøril Aasen; Wade, Emma Jane; Bjørseth, Kamilla; Breedveld, Gijs D; Straith, Bengt Fredrik; Moe, Kamilla Grotthing; Jartun, Morten; Høisæter, Åse

    2017-03-01

    Aqueous film-forming foams (AFFF) containing poly- and perfluoroalkyl substances (PFAS) used for firefighting have led to the contamination of soil and water at training sites. The unique physicochemical properties of PFAS results in environmental persistency, threatening water quality and making remediation of such sites a necessity. This work investigated the role of sorbent amendment to PFAS contaminated soils in order to immobilise PFAS and reduce mobility and leaching to groundwater. Soil was sampled from a firefighting training facility at a Norwegian airport and total and leachable PFAS concentrations were quantified. Perfluorooctanesulfonic acid (PFOS) was the most dominant PFAS present in all soil samples (between 9 and 2600 μg/kg). Leaching was quantified using a one-step batch test with water (L/S 10). PFOS concentrations measured in leachate water ranged between 1.2 μg/L and 212 μg/L. Sorbent amendment (3%) was tested by adding activated carbon (AC), compost soil and montmorillonite to selected soils. The extent of immobilisation was quantified by measuring PFAS concentrations in leachate before and after amendment. Leaching was reduced between 94 and 99.9% for AC, between 29 and 34% for compost soil and between 28 and 40% for the montmorillonite amended samples. Sorbent + soil/water partitioning coefficients (K D ) were estimated following amendment and were around 8 L/kg for compost soil and montmorillonite amended soil and ranged from 1960 to 16,940 L/kg for AC amended soil. The remediation of AFFF impacted soil via immobilisation of PFAS following sorbent amendment with AC is promising as part of an overall remediation strategy. Copyright © 2016 Elsevier Ltd. All rights reserved.

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

    Gustavo D. Rosales

    2016-09-01

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

  11. Preparation of industrial chemicals by acid leaching from the koga nepheline syenite, southern Swat, lesser Himalayas-Pakistan

    Nizami, A.R.

    2012-01-01

    This paper encompasses the study on the preparation of industrial chemicals by acid leaching from the Koga nepheline syenite, Southern Swat, Lesser Himalayas-Pakistan. These rocks have been studied in detail by many workers to exploit their industrial utility in the form of powdered rock material in glass and ceramics and steel industry. The present authors for the first time carried out acid leaching studies and prepared a number of industrial chemicals, like, alumina, aluminium sulphate, sodium and ammonium alums, sodium sulphate) and sodium bisulphate by simple chemical reactions at bench scale successfully. The developed process is simple and economically viable. It is recommended to exploit this process in cottage industry in the mountainous areas hosting these rocks for the benefit of local population. The research and development work for production of these chemicals at pilot plant and industrial scale is recommended as well. (author)

  12. Performance of waste-based amendments to reduce metal release from mine tailings: One-year leaching behaviour.

    Rodríguez, Luis; Gómez, Rocío; Sánchez, Virtudes; Villaseñor, José; Alonso-Azcárate, Jacinto

    2018-03-01

    A one-year leaching experiment has been conducted in order to assess the effectiveness of several amendments on metal immobilization in mine tailings from an old Pb/Zn mining area of Central Spain (San Quintín mine). Demineralized water was used as leaching solution, selecting doses equivalent to the annual rainfall conditions of the studied area. Columns with mine tailings without any amendment and others treated with 10% of sugar foam (SF), 15% of drinking water treatment sludge (DWS), 30% of paper mill sludge (PMS) and 15% of olive mill waste (OMW) were used. SF, DWS and PMS amendments increased the pH of leachates from values of approximately 4 to around neutrality. Additionally, the release of sulfate ions from the oxidation of pyritic residues was decreased in some extent by SF and DWS amendments. Metal leaching was effectively reduced by the amendments reaching overall decreases with respect to the unamended columns of 79-96% for Pb, 36-100% for Zn, 50-99% for Cu and 44-100% for Cd. The effect of the amendments in leachate pH, sulfate concentration and metal release from mine tailings was kept throughout the whole experimental period. Our results showed that the application of different organic and inorganic amendments based on by-products and waste materials may be a feasible alternative for the restoration of soils around abandoned metal mines. Copyright © 2017 Elsevier Ltd. All rights reserved.

  13. Nitrate accumulation and leaching potential reduced by coupled water and nitrogen management in the Huang-Huai-Hai Plain.

    Huang, Ping; Zhang, Jiabao; Zhu, Anning; Li, Xiaopeng; Ma, Donghao; Xin, Xiuli; Zhang, Congzhi; Wu, Shengjun; Garland, Gina; Pereira, Engil Isadora Pujol

    2018-01-01

    Irrigation and nitrogen (N) fertilization in excess of crop requirements are responsible for substantial nitrate accumulation in the soil profile and contamination of groundwater by nitrate leaching during intensive agricultural production. In this on-farm field trial, we compared 16 different water and N treatments on nitrate accumulation and its distribution in the soil profile (0-180cm), nitrate leaching potential, and groundwater nitrate concentration within a summer-maize (Zea mays L.) and winter-wheat (Triticum aestivum L.) rotation system in the Huang-Huai-Hai Plain over five cropping cycles (2006-2010). The results indicated that nitrate remaining in the soil profile after crop harvest and nitrate concentration of soil solutions at two depths (80cm and 180cm) declined with increasing irrigation amounts and increased greatly with increasing N application rates, especially for seasonal N application rates higher than 190kgNha -1 . During the experimental period, continuous torrential rainfall was the main cause for nitrate leaching beyond the root zone (180cm), which could pose potential risks for contamination of groundwater. Nitrate concentration of groundwater varied from 0.2 to 2.9mgL -1 , which was lower than the limit of 10mgL -1 as the maximum safe level for drinking water. In view of the balance between grain production and environmental consequences, seasonal N application rates of 190kgNha -1 and 150kgNha -1 were recommended for winter wheat and summer maize, respectively. Irrigation to the field capacity of 0-40cm and 0-60cm soil depth could be appropriate for maize and wheat, respectively. Therefore, taking grain yields, mineral N accumulation in the soil profile, nitrate leaching potential, and groundwater quality into account, coupled water and N management could provide an opportunity to promote grain production while reducing negative environmental impacts in this region. Copyright © 2017 Elsevier B.V. All rights reserved.

  14. Enhancement of gold grade through arsenic removal in the gold concentrate using sulfuric acid baking and hot water leaching

    On, Hyun-sung; Lim, Dae-hack; Myung, Eun-ji; Kim, Hyun-soo; Park, Cheon-young

    2017-04-01

    In order to improve gold recovery, in general, the roasting process is carried out on gold concentrate. However in this process, Arsenic(As) is released from the gold concentrate and valuable elements such as Fe, Cu, Zn and Pb are converted into oxides. This causes air pollution through the release of As and loss of valuable elements by discarding the oxide minerals in the tailings. In order to prevent the release of As and the loss of valuable metals, an acid baking experiment was carried out on the gold concentrate with the addition of an H2SO4 solution. The baking effect, H2SO4 concentration effect and the effects of changing the baking time were examined using an electric furnace. In experimental results, soluble metal sulfates such as Rhomboclase and Mikasite were formed in the baked samples as seen through XRD analysis. In hot(70 degree Celsius) water leaching of the roast and baked samples, As the contents leached were 60 times more in the baked sample than the roast sample, and the Fe, Cu, Zn and Pb contents were 17, 10, 14, 13 times in the baked sample than in the roast sample, respectively. In the water leached solid-residues, the maximum gold grade was upgraded by 33% due to the acid baking effect. It is confirmed that acid baking with H2SO4 prevented As release into the air and the recovery of valuable metals through hot water leaching such as Fe, Cu, Zn and Pb which were formerly discarded in the tailings. Acknowledgment : This work was supported by the Energy and Resources Engineering Program Grant funded by the Ministry of Trade, Industry and Energy, Korea

  15. The influence of reduced tillage on water regime and nutrient leaching in a loamy soil

    Baigys, Giedrius; Gaigalis, Kazimieras; Kutra, Ginutis

    2006-01-01

    The effect of tillage technologies and terms on soil moisture regime and nitrate leaching was studied in field trials carried out on 0.76-1.36-ha fields. The study site was arranged in Pikeliai village (Kėdainiai district). The soil prevailing in the study site is Endocalcari - Endohypogleic Cambisol, sandy light loam and sandy loam on deeper layers of sandy loam and sandy light loam. The arable horizon contains sandy light loam, which is characteristic of the soils prevailing in the Middle L...

  16. Acidic leaching of potentially toxic metals cadmium, cobalt, chromium, copper, nickel, lead, and zinc from two Zn smelting slag materials incubated in an acidic soil.

    Liu, Taoze; Li, Feili; Jin, Zhisheng; Yang, Yuangen

    2018-07-01

    A column leaching study, coupled with acid deposition simulation, was conducted to investigate the leaching of potentially toxic metals (PTM) from zinc smelting slag materials (SSM) after being incubated in an acid Alfisol for 120 days at room temperature. Two SSMs (SSM-A: acidic, 10 yrs exposure with moderate high PTM concentrations versus SSM-B: alkaline, 2 yrs exposure with extremely high PTM concentrations), were used for the incubation at 0.5, 1, 2.5, 5 wt% amendment ratios in triplicate. Five leaching events were conducted at day 1, 3, 7, 14, and 28, and the leaching of PTMs mainly occurred in the first three leaching events, with the highest PTM concentrations in leachate measured from 5 wt% SSM amendments. After leaching, 2.5, 12, 5.5, 14, 11, and 9 wt% of M3 extractable Pb, Zn, Cd, Co, Cr, and Ni could be released from 5 wt% SSM-A amended soils, being respectively 25, 12, 4, 2, 2, and 2 times more than those from 5 wt% SSM-B amended soils. In the leachates, the concentrations of PTMs were mostly affected by leachant pH and were closely correlated to the concentrations of Fe, Al, Ca, Mg and P with Cd, Pb, and Zn showing the most environmental concern. Visual MINTEQ 3.1 modeling suggested metallic ions and sulfate forms as the common chemical species of PTMs in the leachates; whereas, organic bound species showed importance for Cd, Pb, Cu, and Ni, and CdCl + was observed for Cd. Aluminum hydroxy, phosphate, and sulfate minerals prevailed as the saturated minerals, followed by chloropyromorphite (Pb 5 (PO 4 ) 3 Cl) and plumbogummite (PbAl 3 (PO 4 ) 2 (OH) 5 ·H 2 O) in the leachates. This study suggested that incubation of SSMs in acidic soil for a long term can enhance the release of PTMs as the forms of metallic ions and sulfate when subjected to acid deposition leaching. Copyright © 2018 Elsevier Ltd. All rights reserved.

  17. 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

    2016-01-01

    Highlights: • Ammoniacal leaching is used to recover spent Li-ion battery cathode materials. • Leaching agents consist of ammonia, ammonium sulfite and ammonium carbonate. • Ammonium sulfite is a reductant and ammonium carbonate acts as pH buffer. • Co and Cu can be fully leached while Mn and Al are not leached. • Co recovery via ammoniacal leaching is economical compared to acid leaching. - Abstract: 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 LiMn_2O_4, LiCo_xMn_yNi_zO_2_, Al_2O_3 and C while the leach residue is composed of LiNi_xMn_yCo_zO_2, LiMn_2O_4, Al_2O_3, MnCO_3 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.

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

    Fazlullin, M.I.; Boitsov, A.V.

    2002-01-01

    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

  19. Preliminary Study on the Dissolutions of Ce, Nd, Y and La from Mineral Cassiterite by Acid and Alkaline Leaching

    Firdiyono, F.; Andriyah, L.; Aini, F. N.; Arini, T.; Lalasari, L. H.

    2018-03-01

    Rare Earth Metal is a rare element that its availability in nature is very small. In Indonesia, the potential of rare earth metals is generally found as the associated mineral in major commodities, especially gold and alluvial tin. These associated minerals can be processed using a particular technology so that the result is a by-product that can increase the added value of the mineral. This purpose of this research was to investigate the dissolution of Cerium (Ce), Neodymium (Nd), Yttrium (Y) and Lanthanum (La) from mineral cassiterite by leaching process using dilute hydrochloric acid (HCl), sulfate acid (H2SO4) and sodium hydroxide (NaOH). Firstly, cassiterite was grinded to -100 mesh of particle size and characterized by X-Ray Diffraction (XRD) and X-Ray Fluorescence (XRF) techniques. Secondly, 10 gram of cassiterite was leached in 100 ml solution of 3.26 N HCl, H2SO4 and NaOH at variation leaching time of 2, 4, 6, 24 and 48 hours in atmospheric conditions. The products were then filtered to separate filtrate and residue of cassiterite. Finally, to investigate the dissolution of Ce, La, Nd and Y, filtrate from dissolved cassiterite was analyzed by Induced Coupled Plasma-Optical Emission Spectrometry (ICP-OES), while to know the chemical composition of cassiterite leached by dilute HCl, H2SO4 and NaOH, residue products of cassiterite was characterized by XRF analysis. The result of ICP-OES analysis showed the dissolution of Ce element higher than Nd, Y and La elements for leaching cassiterite using HCl, H2SO4 and NaOH. The increase of leaching time was accompanied by the rise in the amount of dissolved elements from cassiterite. The result of XRF analysis showed the chemistry composition of Ce, Nd, Y and La elements on residue decreased insignificantly from chemistry composition of cassiterite (raw mineral) in all conditions. However, the dissolution of Ce, La, Nd and Y was insignificant in all conditions.

  20. Acid leaching of heavy metals from contaminated soil collected from Jeddah, Saudi Arabia: kinetic and thermodynamics studies

    Shorouq I. Alghanmi

    2015-09-01

    Full Text Available Urban soils polluted with heavy metals are of increasing concern because it is greatly affecting human health and the ecological systems. Hence, it is mandatory to understand the reasons behind this pollution and remediate the contaminated solid. The removal of heavy metals from contaminated soil samples collected from the vicinity of the sewage lake in Jeddah, Saudi Arabia, was explored. The leaching process was studied kinetically and thermodynamically for better understanding of the remediation process. The results showed that the soil samples were slightly basic in nature, and tend to be more neutral away from the main contaminated sewage lake area. The total metal content in the soil samples was measured using the aqua regia extractions by ICP-OES and the results showed that many of the heavy metals present have significant concentrations above the tolerable limits. In general, the metal concentrations at different sites indicated that the heavy metal pollution is mainly due to the sewage discharge to the lake. The results showed excellent correlation between the concentrations of Co, As, and Hg with the distance from the main contaminated area. The leaching of Co, As, and Hg using 1.0 M hydrochloric acid from the soil was studied kinetically at different temperatures and the experimental results were fitted using different kinetics models. The experimental data were best described with two-constant rate and Elovich equation kinetic models. Also, the thermodynamic study showed that the leaching process was spontaneous, endothermic and accompanied with increase in the entropy. In general, the polluted soil could be remediated successfully from the heavy metals using the acid leaching procedure in a short period of time.

  1. Co-treatment of spent cathode carbon in caustic and acid leaching process under ultrasonic assisted for preparation of SiC.

    Yuan, Jie; Xiao, Jin; Li, Fachuang; Wang, Bingjie; Yao, Zhen; Yu, Bailie; Zhang, Liuyun

    2018-03-01

    Spent cathode carbon (SCC) from aluminum electrolysis has been treated in ultrasonic-assisted caustic leaching and acid leaching process, and purified SCC used as carbon source to synthesize silicon carbide (SiC) was investigated. Chemical and mineralogical properties have been characterized by X-ray diffraction (XRD), X-ray fluorescence (XRF), scanning electron microscopy (SEM), and thermogravimetry and differential scanning calorimetry (TGA-DSC). Various experimental factors temperature, time, liquid-solid ratio, ultrasonic power, and initial concentration of alkali or acid affecting on SCC leaching result were studied. After co-treatment with ultrasonic-assisted caustic leaching and acid leaching, carbon content of leaching residue was 97.53%. SiC power was synthesized by carbothermal reduction at 1600 °C, as a result of yield of 76.43%, and specific surface area of 4378 cm 2 /g. This is the first report of using purified SCC and gangue to prepare SiC. The two industrial wastes have been used newly as secondary sources. Furthermore, ultrasonic showed significant effect in SCC leaching process. Copyright © 2017 Elsevier B.V. All rights reserved.

  2. Investigation of ATR-FTIR spectroscopy as an alternative to the Water Leach Free Acidity test for cellulose acetate-based film

    Johansen, Karin Bonde; Shashoua, Yvonne

    2005-01-01

    Cellulose acetate film loses acetate groups on ageing which results in the formation of damaging acetic acid. Water-Leach Free Acidity Test (WLFAT) is the definitive technique to quantify acidity, but requires 1g film and 26 hours. ATR-FTIR spectroscopy is a non-destructive, rapid technique which...

  3. Biosynthesis of nano cupric oxide on cotton using Seidlitzia rosmarinus ashes utilizing bio, photo, acid sensing and leaching properties.

    Bashiri Rezaie, Ali; Montazer, Majid; Rad, Mahnaz Mahmoudi

    2017-12-01

    In this research, a facile, rapid and eco-friendly method is introduced for synthesis and loading of cupric oxide on cellulosic chains of cotton fabric with functional properties. Seidlitzia rosmarinus ashes and copper acetate were employed as a natural source of alkaline and metal salt without further chemical materials. The treated samples indicated very good antibacterial activities toward both pathogen Staphylococcus aureus as Gram-positive and Escherichia coli as Gram-negative bacteria. Significant self-cleaning properties against degradation of methylene blue stain under UV irradiation were found. The sensing properties of high concentrated inorganic and organic acids such as sulfuric and formic acids based on colorimetric alterations of the treated fabrics were also confirmed showing acid leaching effects of the treated fabrics. Further, the treated samples showed coloring effects with an enhancement on the physio-mechanical properties including tensile strength, crease recovery angle and hydrophobocity. Copyright © 2017 Elsevier Ltd. All rights reserved.

  4. 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.

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

    Ono, Y.; Rachi, T.; Yokouchi, M.; Kamimoto, Y.; Nakajima, A.; Okada, K.

    2013-01-01

    Highlights: ► Photocatalyst powder was prepared by acid leaching of TiO 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 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 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 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 2 powder, Degussa P25. The highest rate was obtained in the TiO 2 /HAp composite treated with the dilute (0.25 mol/l) acid in spite of its low content of TiO 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 2 /HAp composites compared with the TiO 2 powders

  6. 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.

  7. Biochar-enhanced composts reduce the potential leaching of nutrients and heavy metals and suppress plant-parasitic nematodes in excessively fertilized cucumber soils.

    Cao, Yune; Gao, Yanming; Qi, Yanbin; Li, Jianshe

    2018-03-01

    Excessive fertilization is a common agricultural practice that has largely reduced soil nutrient retention capacity and led to nutrient leaching in China. To reduce nutrient leaching, in this study, we evaluated the application of biochar, compost, and biochar-compost on soil properties, leaching water quality, and cucumber plant growth in soils with different nutrient levels. In general, the concentrations of nutrients and heavy metals in leaching water were higher under high-nutrient conditions than under low-nutrient conditions. Both biochar and compost efficiently enhanced soil cation exchange capacity (CEC), water holding capacity (WHC), and microbial biomass carbon (MBC), nitrogen (MBN), and phosphorus (MBP), reduced the potential leaching of nutrients and heavy metals, and improved plant growth. The efficiency of biochar and compost in soil CEC, WHC, MBC, MBN, and MBP and plant growth was enhanced when applied jointly. In addition, biochar and biochar-enhanced compost efficiently suppressed plant-parasitic nematode infestation in a soil with high levels of both N and P. Our results suggest that biochar-enhanced compost can reduce the potential environmental risks in excessively fertilized vegetable soils.

  8. The effects of gamma irradiation on the leaching of reducing sugars, inorganic phosphate and enzymes from barley seeds during germination in water

    Kurobane, I.; Yamaguchi, H.; Sander, C.; Nilan, R.A.

    1979-01-01

    Gamma irradiation enhanced the leaching of reducing sugars from barley seeds into the water in which the seeds were shaken. Treatments prior to shaking in water, such as overnight soaking in water at 5 0 C and subsequent germination in Petri dishes for 1 or 2 days at 20 0 C, showed pronounced effects on the leaching. The highest effect, which was obtained at 500 krad irradiation, was four times higher than that of the non-irradiated control. Gamma irradiation also stimulated the leaching of inorganic phosphate and slightly that of amylases from barley seeds. When seeds from which the embryos has been removed were shaken into water, no stimulating effect on the leaching of sugars was noted. These results, combined with the irradiation effect on the embryo, suggest that the stimulated leaching of reducing sugars is due to the extreme difference in sensitivity to gamma irradiation between the production of reducing sugars in the endosperm and the development and growth of the embryo. (author)

  9. 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.

  10. Gold recovery from acidic leach solutions using as extractants trialkylamines of N,N'-di-alkyl-aliphatic amides

    Baroncelli, F.; Carlini, D.; Gasparini, G.M.; Simonetti, E.

    1988-07-01

    TriOctylAmine (TOA) and a di-substituted aliphatic amide, N,N-Di-N-ButylOctanamide (DBOA), were examined in batch and in mini mixer-settler experiments using leachates of Peruvian and Bolivian concentrates. With these minerals, very rich in sulfur (pyrites, stybine), 90-95% gold recovery in 12-24 hours was reached by leaching with 4M aqua regia (HCl 3M nitric acid 1M) at room temperature and with 1/3 solid/liquid ratio. With these leachate solutions (2-3M total acidity, 10-60 ppm ao Au), the two processes with TOA (GAMEX PROCESS) and with DBOA (AUMIDEX PROCESS) were tested and compared. Experimental results strongly support the possibility of using TOA and DBOA on an industrial scale.

  11. 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

    2016-08-05

    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. Copyright © 2016 Elsevier B.V. All rights reserved.

  12. Comparison of 2-Octanol and Tributyl Phosphate in Recovery of Tungsten from Sulfuric-Phosphoric Acid Leach Solution of Scheelite

    Liao, Yulong; Zhao, Zhongwei

    2018-04-01

    Tungsten was recovered from sulfuric-phosphoric acid leach solution of scheelite using 2-octanol and tributyl phosphate (TBP). Approximately 76% of the tungsten and less than 6.2% of the iron were extracted when using 70% 2-octanol, showing good selectivity for tungsten over iron; the tungsten extraction could not be significantly enhanced using a three-stage countercurrent simulation test. Moreover, more than 99.2% of the W and 91.0% of the Fe were extracted when using 70% TBP, showing poor selectivity, but after pretreating the leach solution with iron powder, less than 5.5% of the Fe was extracted. The loaded phases were stripped using deionized water and ammonia solution. The maximum stripping rate of tungsten from loaded 2-octanol was 45.6% when using water, compared with only 13.1% from loaded TBP. Tungsten was efficiently stripped from loaded phases using ammonia solution without formation of Fe(OH)3 precipitate. Finally, a flow sheet for recovery of tungsten with TBP is proposed.

  13. Demonstration of the efficiency and robustness of an acid leaching process to remove metals from various CCA-treated wood samples.

    Coudert, Lucie; Blais, Jean-François; Mercier, Guy; Cooper, Paul; Janin, Amélie; Gastonguay, Louis

    2014-01-01

    In recent years, an efficient and economically attractive leaching process has been developed to remove metals from copper-based treated wood wastes. This study explored the applicability of this leaching process using chromated copper arsenate (CCA) treated wood samples with different initial metal loading and elapsed time between wood preservation treatment and remediation. The sulfuric acid leaching process resulted in the solubilization of more than 87% of the As, 70% of the Cr, and 76% of the Cu from CCA-chips and in the solubilization of more than 96% of the As, 78% of the Cr and 91% of the Cu from CCA-sawdust. The results showed that the performance of this leaching process might be influenced by the initial metal loading of the treated wood wastes and the elapsed time between preservation treatment and remediation. The effluents generated during the leaching steps were treated by precipitation-coagulation to satisfy the regulations for effluent discharge in municipal sewers. Precipitation using ferric chloride and sodium hydroxide was highly efficient, removing more than 99% of the As, Cr, and Cu. It appears that this leaching process can be successfully applied to remove metals from different CCA-treated wood samples and then from the effluents. Copyright © 2013 Elsevier Ltd. All rights reserved.

  14. A recovery of gold from electronic scrap by mechanical separation, acid leaching and electrowinning

    Rhee, K.I.; Lee, J.C.; Lee, C.K.; Joo, K.H.; Yoon, J.K.; Kang, H.R.; Kim, Y.S.; Sohn, H.J.

    1995-12-31

    A series of processes to recover the gold from electronic scrap which contains initially about 200--600 ppm Au have been developed. First, mechanical beneficiation including shredding, crushing and screening was employed. Results showed that 99 percent of gold component leaves in the fraction of under 1 mm of crushed scrap and its concentration was enriched to about 800 ppm without incineration. The scrap was leached in 50% aqua regia solution and gold was dissolved completely at 60 C within 2 hours. Other valuable metals such as silver, copper, nickel and iron were also dissolved. This resulting solution was boiled to remove nitrous compounds in the leachate. Finally, a newly designed electrolyzer was tested to recover the gold metal. More than 99% of gold and silver were recovered within an hour in electrowinning process.

  15. Evaluation of acid leaching method for the determination of uranium in fecal samples from occupational workers at Tarapur

    Raveendran, Nanda; Dubla, Rupali; Yadav, J.R.; Rao, D.D.; Baburajan, A.

    2015-01-01

    Assessment of internal contamination due to inhalation, ingestion or injection of radionuclides to occupational workers is carried out by analysis of excreta samples and whole body counting. Routine monitoring of radiation workers for assessing actinides intake are done either by urine or fecal sample analysis. This paper deals with the evaluation of analytical method for the determination of isotopes of uranium in fecal samples submitted by occupational workers from operating plants at Tarapur. The method involves sample ashing, addition of 232 U tracer for radiochemical recovery and acid leaching preconcentration stage followed by anion exchange separation. Thirteen routine fecal samples submitted by radiation workers under their routine monitoring practices were collected and analyzed. Radiochemical tracer recovery was obtained in the range of 52% to 86.4 % with a mean and standard deviation of 64.7% and 12.3% respectively. (author)

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

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

    2011-10-29

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

  17. 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.

  18. Effects of structural and textural grain characteristics on leaching of sulphide minerals from a polymetallic concentrate by sodium nitrate and sulphuric acid solution

    Sokić Miroslav D.

    2017-01-01

    Full Text Available In this paper, the influence of structural and textural characteristics of sulfide minerals on their leaching from a polymetallic concentrate by sulfuric acid and sodium nitrate solution is presented. The starting material was Pb–Zn–Cu sulphide polymetallic concentrate enriched during the flotation of a polymetallic ore in the "Rudnik" flotation plant (Rudnik – Serbia. Leaching experiments were carried out in a closed glass reactor, which provides stable hermetic conditions and allows heating at constant temperature. Chemical, XRD, qualitative and quantitative microscopic and SEM/EDX analyses were used to characterizes samples of the polymetallic concentrate and leach residue. It was determined that chalcopyrite, sphalerite, galena, pyrrhotite and quartz were present in the polymetallic concentrate. The content of sulphide minerals was 69.5%, of which 60.9% occurred as liberated grains: 88.3% of chalcopyrite, 59.3% of sphalerite, 25.1% of galena and 51.6% of pirrhotite. The rest of chalcopyrite, sphalerite, galena and pirrhotite grains were in the forms of inclusions, impregnations, and simple and complex intergrowths. During the leaching process by sodium nitrate and sulphuric acid solution, it was shown previously that the leaching rate of sulphide minerals decreased with time while a part of the sulphide minerals remained in the leach residue. After leaching at 80°C for 120 min, the yields were 69.8, 82.7 and 67.1% for Cu, Zn and Fe, respectively. Lead, in the form of insoluble anglesite, remained in the leach residue. In addition to the anglesite, unleached sulfide minerals and quartz, elemental sulfur was found in the solid residue. The content of sulphide minerals was 35% of which 33.7% minerals occur independently. In specific, 54.7% of chalcopyrite, 31.9% of sphalerite, 8.2% of galena and 37.6% of pyrrhotite appear as separate grains with highly corroded surfaces. Therefore, the structural assembly of sulphide grains in the

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

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

    2009-09-01

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

  20. Review of Alternative Management Options of Vegetable Crop Residues to Reduce Nitrate Leaching in Intensive Vegetable Rotations

    Laura Agneessens

    2014-12-01

    Full Text Available Vegetable crop residues take a particular position relative to arable crops due to often large amounts of biomass with a N content up to 200 kg N ha−1 left behind on the field. An important amount of vegetable crops are harvested during late autumn and despite decreasing soil temperatures during autumn, high rates of N mineralization and nitrification still occur. Vegetable crop residues may lead to considerable N losses through leaching during winter and pose a threat to meeting water quality objectives. However, at the same time vegetable crop residues are a vital link in closing the nutrient and organic matter cycle of soils. Appropriate and sustainable management is needed to harness the full potential of vegetable crop residues. Two fundamentally different crop residue management strategies to reduce N losses during winter in intensive vegetable rotations are reviewed, namely (i on-field management options and modifications to crop rotations and (ii removal of crop residues, followed by a useful and profitable application.

  1. Assessment of some straw-derived materials for reducing the leaching potential of Metribuzin residues in the soil

    Cara, Irina Gabriela, E-mail: coroirina@yahoo.com [“Ion Ionescu de la Brad” University of Agricultural Sciences and Veterinary Medicine, Faculty of Agriculture, 3M. Sadoveanu Alley, 700490 Iasi (Romania); Trincă, Lucia Carmen, E-mail: lctrinca@uaiasi.ro [“Ion Ionescu de la Brad” University of Agricultural Sciences and Veterinary Medicine, Faculty of Horticulture, 3 M. Sadoveanu Alley, 700490 Iasi (Romania); Trofin, Alina Elena, E-mail: aetrofin@yahoo.com [“Ion Ionescu de la Brad” University of Agricultural Sciences and Veterinary Medicine, Faculty of Horticulture, 3 M. Sadoveanu Alley, 700490 Iasi (Romania); Cazacu, Ana, E-mail: anagarlea@gmail.com [“Ion Ionescu de la Brad” University of Agricultural Sciences and Veterinary Medicine, Faculty of Horticulture, 3 M. Sadoveanu Alley, 700490 Iasi (Romania); Ţopa, Denis, E-mail: topadennis@yahoo.com [“Ion Ionescu de la Brad” University of Agricultural Sciences and Veterinary Medicine, Faculty of Agriculture, 3M. Sadoveanu Alley, 700490 Iasi (Romania); Peptu, Cătălina Anişoara, E-mail: catipeptu@yahoo.co.uk [“Gheorghe Asachi” Technical University of Iasi, Faculty of Chemical Engineering and Environmental Protection, 73 D. Mangeron Street, 700050 Iasi (Romania); Jităreanu, Gerard, E-mail: gerardj@uaiasi.ro [“Ion Ionescu de la Brad” University of Agricultural Sciences and Veterinary Medicine, Faculty of Agriculture, 3M. Sadoveanu Alley, 700490 Iasi (Romania)

    2015-12-15

    Highlights: • Surface characteristics of activated straw (wheat, corn, soybean) were assessed. • Modification methods to enhance materials sorption were presented. • Adsorption mechanism of metribuzin was revealed and discussed. - Abstract: Biomass (straw waste) can be used as raw to obtain materials for herbicide removal from wastewater. These by-products have some important advantages, being environmentally friendly, easily available, presenting low costs, and requiring little processing to increase their adsorptive capacity. In the present study, some materials derived from agricultural waste (wheat, corn and soybean straw) were investigated as potential adsorbents for metribuzin removal from aqueous solutions. The straw wastes were processed by grinding, mineralisation (850 °C) and KOH activation in order to improve their functional surface activity. The materials surface characteristics were investigated by scanning electron microscopy, energy dispersive X-ray spectroscopy and atomic force microscopy. The adsorbents capacity was evaluated using batch sorption tests and liquid chromatography coupled with mass spectrometry for herbicide determination. For adsorption isotherms, the equilibrium time considered was 3 h. The experimental adsorption data were modelled by Freundlich and Langmuir models. The activated straw and ash-derived materials from wheat, corn and soybean increased the adsorption capacity of metribuzin with an asymmetrical behaviour. Overall, our results sustain that activated ash-derived from straw and activated straw materials can be a valuable solution for reducing the leaching potential of metribuzin through soil.

  2. Assessment of some straw-derived materials for reducing the leaching potential of Metribuzin residues in the soil

    Cara, Irina Gabriela; Trincă, Lucia Carmen; Trofin, Alina Elena; Cazacu, Ana; Ţopa, Denis; Peptu, Cătălina Anişoara; Jităreanu, Gerard

    2015-01-01

    Highlights: • Surface characteristics of activated straw (wheat, corn, soybean) were assessed. • Modification methods to enhance materials sorption were presented. • Adsorption mechanism of metribuzin was revealed and discussed. - Abstract: Biomass (straw waste) can be used as raw to obtain materials for herbicide removal from wastewater. These by-products have some important advantages, being environmentally friendly, easily available, presenting low costs, and requiring little processing to increase their adsorptive capacity. In the present study, some materials derived from agricultural waste (wheat, corn and soybean straw) were investigated as potential adsorbents for metribuzin removal from aqueous solutions. The straw wastes were processed by grinding, mineralisation (850 °C) and KOH activation in order to improve their functional surface activity. The materials surface characteristics were investigated by scanning electron microscopy, energy dispersive X-ray spectroscopy and atomic force microscopy. The adsorbents capacity was evaluated using batch sorption tests and liquid chromatography coupled with mass spectrometry for herbicide determination. For adsorption isotherms, the equilibrium time considered was 3 h. The experimental adsorption data were modelled by Freundlich and Langmuir models. The activated straw and ash-derived materials from wheat, corn and soybean increased the adsorption capacity of metribuzin with an asymmetrical behaviour. Overall, our results sustain that activated ash-derived from straw and activated straw materials can be a valuable solution for reducing the leaching potential of metribuzin through soil.

  3. 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

    2016-01-01

    Highlights: • An integrated process for the stepwise disposal of red mud was proposed. • Extracting and recovering Ti from Ti-enriched tailing was the second step. • The factors influencing acid leaching and precipitate flotation were examined. • The extracting of metals in concentrated H 2 SO 4 was controlled by diffusion reactions. • [Hbet][Tf 2 N] was an effective precipitating reagent with its coordination mechanism. - Abstract: 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][Tf 2 N] as precipitating reagent were discussed. The extracting of Ti 4+ , Al 3+ and Fe 3+ in concentrated H 2 SO 4 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][Tf 2 N], 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 15.5 g/L, Al 3+ of 30.4 g/L and Fe 3+ of 0.48 g/L was obtained for the following hydrolysis step in the integrated process for red mud utilisation.

  4. 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. Copyright © 2015 Elsevier Ltd. All rights reserved.

  5. Glass-surface area to solution-volume ratio and its implications to accelerated leach testing

    Pederson, L.R.; Buckwalter, C.Q.; McVay, G.L.; Riddle, B.L.

    1982-10-01

    The value of glass surface area to solution volume ratio (SA/V) can strongly influence the leaching rate of PNL 76-68 glass. The leaching rate is largely governed by silicon solubility constraints. Silicic acid in solution reduced the elemental release of all glass components. No components are leached to depths greater than that of silicon. The presence of the reaction layer had no measurable effect on the rate of leaching. Accelerated leach testing is possible since PNL 76-68 glass leaching is solubility-controlled (except at very low SA/V values). A series of glasses leached with SA/V x time = constant will yield identical elemental release

  6. Resistance evaluation expanded perlite the leaching acid: variation of parameters concentration, time and leaching agent; Avaliacao da resistencia da perlita expandida a lixiviacao acida: variacao dos parametros concentracao, tempo e agente lixiviante

    Almeida, J.M.F. de; Damasceno Junior, E.; Oliveira, E.S.; Fernandes, N.S., E-mail: janielequimicaufrn@gmail.com [Universidade Federal do Rio Grande do Norte (UFRN), Natal, RN (Brazil). Instituto de Quimica. Laboratorio de Quimica Analitica e Meio Ambiente

    2016-07-01

    The expanded perlite is an amorphous aluminosilicate which presents in its composition about 75.0% silicon oxide (SiO2), also having other species in the composition as oxides of some metals. Silicas and silicates have been used in the environmental field, in relevant anti-corrosive activity. In this context, materials that exposes too many highly acidic media, require preservation against this type of wear, as this type of damage causes a great financial loss, thereby requiring low-cost, abundant materials, non-toxic and easy to purchase as some silica coating. The study evaluated the perlite expanded resistance against an acid leaching process. With undeniability the use of strong acids and different working conditions were not able to remove the oxides present on the expanded perlite sample, thus demonstrating the high strength of the expanded perlite against acid attacks. (author)

  7. 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. Copyright © 2014 Elsevier Inc. All rights reserved.

  8. Speciation analysis and leaching behaviors of selected trace elements in spent SCR catalyst.

    Dai, Zejun; Wang, Lele; Tang, Hao; Sun, Zhijun; Liu, Wei; Sun, Yi; Su, Sheng; Hu, Song; Wang, Yi; Xu, Kai; Liu, Liang; Ling, Peng; Xiang, Jun

    2018-09-01

    This study investigated heavy metal chemical speciation and leaching behavior from a board-type spent selective catalytic reduction (SCR) catalyst containing high concentrations of vanadium, chromium, nickel, copper, zinc, and lead. A three-step sequential extraction method, standard toxicity characteristic leaching procedure (TCLP), and leaching characteristic tests have been performed. It was found that the mobility of six heavy metals in the spent SCR catalyst was significantly different. The mobility of the six heavy metals exhibited the following order: Ni > Zn > V > Cr > As > Cu. Meanwhile, TCLP test results revealed relatively high Zn and Cr leaching rate of 83.20% and 10.35%, respectively. It was found that leaching rate was positively correlated with available contents (sum of acid soluble, reducible and oxidizable fractions). Leaching characteristics tests indicated that pH substantially affected the leaching of these heavy metals. In particular, the leaching of Cr, Ni, Cu, and Zn was positively influenced by strong acid, while V and As were easily released in the presence of strong acid and strong alkali (pH 11). In terms of kinetics, the leaching of Cr, Ni, Cu, Zn, and As within the spent catalyst was dominated by erosion and dissolution processes, which were rapid reaction processes. V was released in large amounts within 1 h, but its leaching amount sharply decreased with time due to readsorption. Copyright © 2018 Elsevier Ltd. All rights reserved.

  9. Application of percolation leaching in Fuzhou uranium mine

    Jiang Lang; Wang Haita; He Jiangming

    2006-01-01

    In order to solve these problems such as high cost by conventional agitation leaching, low permeability and low leaching rate by heap leach, a percolation leaching method was developed. Two-year's production results show that leaching rate of uranium is up to 90% by this method. Compared with conventional agitation leaching, the power, sulfuric acid and lime consumption by the percolation leaching decreased by 60%, 27% and 77% respectively. (authors)

  10. Separation of cerium from other lanthanides by leaching with nitric acid rare earth(III) hydroxide-cerium(IV) oxide mixtures

    Mioduski, T.; Dong Anh Hao; Hoang Hong Luan

    1989-01-01

    The objective of the present work is a method for separating Ce from other Ln in the raw natural mixtures of rare earth hydroxides obtained from Vietnamese and Mongolian fluorocarbonate ores. The method, a simple acid digestion, should combine a maximum Ln(III) concentration of the effluent solution with a nitrate counter-ion environment and high selectivity vs. leaching yield parameters. Under optimum conditions Ce (and Th, if present) virtually does not pass into solution while the yield of leaching and the sum of REE oxides concentration in the after-leach solution reach the maximum values of 97% (mass) and 0.18 kg x dm -3 , respectively. (author) 9 refs.; 8 tabs

  11. Leaching of Cu, Cd, Pb, and phosphorus and their availability in the phosphate-amended contaminated soils under simulated acid rain.

    Cui, Hongbiao; Zhang, Shiwen; Li, Ruyan; Yi, Qitao; Zheng, Xuebo; Hu, Youbiao; Zhou, Jing

    2017-09-01

    Phosphate amendments have been used to immobilize heavy metal-contaminated soils. However, phosphate amendments contain large amounts of phosphorus, which could leach out to potentially contaminate groundwater and surface water. A laboratory column leaching experiment was designed to study the effects of simulated acid rain (SAR) on the potential release of copper (Cu), lead (Pb), cadmium (Cd), and phosphorus (P), and their availability after immobilizing with hydroxyapatite (HAP) and potassium dihydrogen phosphate (PDP). The application of HAP and PDP enhanced the leachate electrical conductivity, total organic carbon, and pH. Higher P was found in the PDP- (>4.29 mg L -1 ) and HAP-treated (>1.69 mg L -1 ) columns than that in untreated (phosphate amendments might promote the leaching of some metals while immobilizing others.

  12. Queensland Mines plant trials with Caro's acid

    Lucas, G.C.; Fulton, E.J.; Vautier, F.E.; Waters, D.J.; Ring, R.J.

    1983-01-01

    Laboratory leach tests have been carried out to compare the effectiveness of Caro's acid (permonosulphuric acid) as an alternative oxidant to pyrolusite in the leaching of uranium ores. Results demonstrated that Caro's acid reduced acid consumption in leaching and the time required for neutralisation of tailings liquor. The uranium extraction was unaffected by choice of oxidant. A plant trial confirmed that significant savings in acid and lime usage can be achieved under plant conditions. Plant operations also demonstrated that Caro's acid has a number of significant operating advantages over pyrolusite. Queensland Mines Ltd. have recently decided to convert their leaching process from pyrolusite to Caro's acid

  13. Commercial experimental on bacteria heap leaching of uranium ore from Caotaobei mining area in Ganzhou uranium mine

    Fan Baotuan; Meng Yunsheng; Liu Jian; Xiao Jinfeng; Chen Sencai; Cao Jianbo; Wu Yichang; Liu Chengwu

    2002-01-01

    The author presents the result of commercial experiment on bacteria heap leaching of uranium ore from Caotaobei mining area in Ganzhou Uranium Mine and summarizes the heap situation, installation of spraying and sprinkling devices, and operation management of continuous oxidizing tank of bio-membrane. The leaching rate is 92.95% and 91.88% respectively by liquid and residue measurement during 85 d bacterial leaching experiment. The acid consumption is 2.1% and the total liquid-solid ratio is 2.9 m 3 /t. Compared with conventional heap leaching, the time of bacteria heap leaching shorted about 75 d, the acid consumption reduced by 0.35% and the leaching rate improved by 2%. It is an optimize plan to reform the heap leaching technology for Caotaobei ore

  14. Study on extraction of uranium from clayey sandstone with floatation-leaching process

    Meng Guangshou; Zhao Manchang; Wu Peisheng; Song Wenlan; Li Wenxia.

    1985-01-01

    An improved floatation-leaching process is proposed to extract uranium from some clayey sandstone type of ore. By two-step flotation, the ground feed ore can be divided into three urani-ferous sections, i.e., the sulfidic concentrate carrying organic matter, the carbonate concentrate, and the tailings. The sulfidic concentrate is mixed with the tailings and then treated by acid-leaching with the result that 93% uranium extraction can be attained. The excess free acid of the leached slurry is further neutralized with the carbonate concentrate instead of lime commonly used. As a result, approximately 60% uranium extraction can be attained. As a whole, by the flotation-leaching process the acid consumption can be reduced from 200 kg/t down to < 80 kg/t and the uranium extraction can be raised from 85% to 90% as compared with the conventional acid-leaching process

  15. Optimization of an oil leaching process to reduce the level of dioxins and dioxin-like PCBs in fishmeal.

    Oterhals, Åge; Kvamme, Bjørn

    2013-05-01

    Fishmeal produced from fish caught in polluted fishing areas might contain dioxins and dioxin-like polychlorinated biphenyls (PCBs) above maximum permitted levels (MPL) for use in feed. Decontamination of the fishmeal can be achieved by hexane extraction. The principal objective of this study was to optimize a more environmentally friendly alternative based on oil leaching of the moist presscake intermediate product during fishmeal manufacturing. A central composite design and response surface methodology was used to study the influence of the process variables temperature (T), presscake moisture content (MC) and leaching time (LT) on the decontamination process. A significant squared MC effect was observed, resulting in an optimum leaching rate at 27% MC. This corresponds to 5% improved dibenzo-p-dioxin/dibenzo furan (PCDD/F)-PCB toxic equivalent (TEQ) reduction compared to normal presscake (55% MC). The initial leaching rate was fast, with a TEQ reduction of 69% after only 2 min at 87 °C and 55% MC. Under the best experimental conditions (87 °C, 38% MC, 12 min LT) a TEQ reduction of 82% was achieved. Excess oil in the presscake after the leaching operation could be removed by use of a water washing step. No reduction in protein quality measured by mink digestibility could be observed. The results confirm that the oil leaching process is robust and offers easily achievable TEQ levels well below present MPLs based on process conditions normally used by the industry. Comparative effects on non-dioxin-like PCBs are expected. © 2012 Society of Chemical Industry.

  16. Bacteria heap leaching test of a uranium ore

    Liu Hui; Liu Jinhui; Wu Weirong; Han Wei

    2008-01-01

    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)

  17. Degradation rates and mechanisms of acid-resistant coatings in copper-leaching tanks

    Møller, Victor Buhl

    coating where the lifetime was estimated to 1:6 ± 0:2 and 1:4 ± 0:1 years, respectively. Part IV A series of newly designed and constructed diffusion cells were used to measure sulfuric acid diffusion rates through the coatings. A mathematical model was developed to simulate the experimental data...... potential in the mineral industry has not yet been thoroughly investigated. This particular industry poses unique challenges, with high operational temperatures (around 75 °C) and combined acidicerosive environments. The use of organic coatings to protect tanks, pipes, and secondary exposure areas, may....... Part I An in-depth literature study was performed to uncover and review uses and limitations ofacid-resistant coatings in the chemical industry, with a comparison to alternative resistant materialsbased on metals and ceramics. In addition, coating degradation phenomena caused by acid exposure, were...

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

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

    2012-04-01

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

  19. Synthesis and characterization of Co3O4 prepared from atmospheric pressure acid leach liquors of nickel laterite ores

    Meng, Long; Guo, Zhan-cheng; Qu, Jing-kui; Qi, Tao; Guo, Qiang; Hou, Gui-hua; Dong, Peng-yu; Xi, Xin-guo

    2018-01-01

    A chemical precipitation-thermal decomposition method was developed to synthesize Co3O4 nanoparticles using cobalt liquor obtained from the atmospheric pressure acid leaching process of nickel laterite ores. The effects of the precursor reaction temperature, the concentration of Co2+, and the calcination temperature on the specific surface area, morphology, and the electrochemical behavior of the obtained Co3O4 particles were investigated. The precursor basic cobaltous carbonate and cobaltosic oxide products were characterized and analyzed by Fourier transform infrared spectroscopy, thermogravimetric differential thermal analysis, X-ray diffraction, field-emission scanning electron microscopy, specific surface area analysis, and electrochemical analysis. The results indicate that the specific surface area of the Co3O4 particles with a diameter of 30 nm, which were obtained under the optimum conditions of a precursor reaction temperature of 30°C, 0.25 mol/L Co2+, and a calcination temperature of 350°C, was 48.89 m2/g. Electrodes fabricated using Co3O4 nanoparticles exhibited good electrochemical properties, with a specific capacitance of 216.3 F/g at a scan rate of 100 mV/s.

  20. Bacterial Leaching

    and studies microbial biotechnology and ... foundation for subsequent research into the role of microorgan- ... are more readily accesible, for example those in solution, rather .... Vat leaching as currently applied to oxide ores involves the.

  1. 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)

  2. 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. Copyright © 2016 Elsevier B.V. All rights reserved.

  3. UV-irradiation and leaching in water reduce the toxicity of imidacloprid-contaminated leaves to the aquatic leaf-shredding amphipod Gammarus fossarum.

    Englert, Dominic; Zubrod, Jochen P; Neubauer, Christoph; Schulz, Ralf; Bundschuh, Mirco

    2018-05-01

    Systemic neonicotinoid insecticides such as imidacloprid are increasingly applied against insect pest infestations on forest trees. However, leaves falling from treated trees may reach nearby surface waters and potentially represent a neonicotinoid exposure source for aquatic invertebrates. Given imidacloprid's susceptibility towards photolysis and high water solubility, it was hypothesized that the leaves' toxicity might be modulated by UV-irradiation during decay on the forest floor, or by leaching and re-mobilization of the insecticide from leaves within the aquatic ecosystem. To test these hypotheses, the amphipod shredder Gammarus fossarum was fed (over 7 d; n = 30) with imidacloprid-contaminated black alder (Alnus glutinosa) leaves that had either been pre-treated (i.e., leached) in water for up to 7 d or UV-irradiated for 1 d (at intensities relevant during autumn in Central Europe) followed by a leaching duration of 1 d. Gammarids' feeding rate, serving as sublethal response variable, was reduced by up to 80% when consuming non-pretreated imidacloprid-contaminated leaves compared to imidacloprid-free leaves. Moreover, both leaching of imidacloprid from leaves (for 7 d) as well as UV-irradiation reduced the leaves' imidacloprid load (by 46 and 90%) thereby mitigating the effects on gammarids' feeding rate to levels comparable to the respective imidacloprid-free controls. Therefore, natural processes, such as UV-irradiation and re-mobilization of foliar insecticide residues in water, might be considered when evaluating the risks systemic insecticide applications in forests might pose for aquatic organisms in nearby streams. Copyright © 2018 Elsevier Ltd. All rights reserved.

  4. Hydrometallurgical Process and Kinetics of Leaching Manganese from Semi-Oxidized Manganese Ores with Sucrose

    Yuhong Wang

    2017-02-01

    Full Text Available The extraction of manganese from a semi-oxidized manganese ore was investigated with sucrose as the reducing agent in dilute sulfuric acid medium. The kinetics of leaching manganese from the complex ore containing MnCO3 and MnO2 was also investigated. The effects of sucrose and sulfuric acid concentrations, leaching temperature and reaction time on the total Mn (TMn, MnO2 and MnCO3 leaching were investigated. Results showed that MnCO3 could more easily react with hydrogen ions than MnO2 in ores, and MnO2 decomposition could be advantageous for MnCO3 leaching. The leaching efficiencies of 91.8% for total Mn, 91.4% for MnO2 and 96.9% for MnCO3 were obtained under the following optimized conditions: 0.035 mol/L sucrose concentration, 5 mol/L sulfuric acid concentration, 60 min of reaction time and 363.2 K of leaching temperature. In addition, it was found that the leaching process of semi-oxidized manganese ore follows the shrinking core model and the leaching rate was controlled by chemical reaction and diffusion. The apparent activation energy of the total manganese, MnO2, and MnCO3 leaching were 40.83, 40.59, and 53.33 kJ·mol−1, respectively.

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

    Ku, Heesuk; Jung, Yeojin; Jo, Minsang; Park, Sanghyuk [Department of Energy & Mineral Resources Engineering, Sejong University, Seoul 05006 (Korea, Republic of); Kim, Sookyung [Urban Mine Department, Korea Institute of Geoscience and Mineral Resources, 124 Gwahang-no, Yuseong-gu, Daejeon (Korea, Republic of); Yang, Donghyo, E-mail: ydh@kigam.re.kr [Urban Mine Department, Korea Institute of Geoscience and Mineral Resources, 124 Gwahang-no, Yuseong-gu, Daejeon (Korea, Republic of); Rhee, Kangin; An, Eung-Mo; Sohn, Jeongsoo [Urban Mine Department, Korea Institute of Geoscience and Mineral Resources, 124 Gwahang-no, Yuseong-gu, Daejeon (Korea, Republic of); Kwon, Kyungjung, E-mail: kfromberk@gmail.com [Department of Energy & Mineral Resources Engineering, Sejong University, Seoul 05006 (Korea, Republic of)

    2016-08-05

    Highlights: • Ammoniacal leaching is used to recover spent Li-ion battery cathode materials. • Leaching agents consist of ammonia, ammonium sulfite and ammonium carbonate. • Ammonium sulfite is a reductant and ammonium carbonate acts as pH buffer. • Co and Cu can be fully leached while Mn and Al are not leached. • Co recovery via ammoniacal leaching is economical compared to acid leaching. - Abstract: 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 LiMn{sub 2}O{sub 4}, LiCo{sub x}Mn{sub y}Ni{sub z}O{sub 2,} Al{sub 2}O{sub 3} and C while the leach residue is composed of LiNi{sub x}Mn{sub y}Co{sub z}O{sub 2}, LiMn{sub 2}O{sub 4}, Al{sub 2}O{sub 3}, MnCO{sub 3} 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.

  6. 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, E-mail: guihong-han@hotmail.com; Wang, Wenjuan; Yang, Shuzhen; Liu, Jiongtian

    2016-04-15

    Highlights: • An integrated process for the stepwise disposal of red mud was proposed. • Extracting and recovering Ti from Ti-enriched tailing was the second step. • The factors influencing acid leaching and precipitate flotation were examined. • The extracting of metals in concentrated H{sub 2}SO{sub 4} was controlled by diffusion reactions. • [Hbet][Tf{sub 2}N] was an effective precipitating reagent with its coordination mechanism. - Abstract: 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{sup 4+}, Al{sup 3+} and Fe{sup 3+}, and the mechanism of selectively Fe{sup 3+} removal using [Hbet][Tf{sub 2}N] as precipitating reagent were discussed. The extracting of Ti{sup 4+}, Al{sup 3+} and Fe{sup 3+} in concentrated H{sub 2}SO{sub 4} is controlled by diffusion reactions, depending mainly upon leaching time and temperature. The maximum extracting efficiency of Ti{sup 4+} is approximately 92.3%, whereas Al{sup 3+} and Fe{sup 3+} leaching are respectively 75.8% and 84.2%. [Hbet][Tf{sub 2}N], as a precipitating reagent, operates through a coordination mechanism in flotation. The pH value is the key factor influencing the flotation recovery of Ti{sup 4+}, whereas the dosage of precipitating reagent is that for Al{sup 3+} recovery. The maximum flotation recovery of Ti{sup 4+} is 92.7%, whereas the maximum Al{sup 3+} recovery is 93.5%. The total recovery rate for extracting and recovering titanium is 85.5%. The liquor with Ti{sup 4+} of 15.5 g/L, Al{sup 3+} of 30.4 g/L and Fe{sup 3+} of 0.48 g/L was obtained for the following hydrolysis step in the integrated process for red mud utilisation.

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

    Fan Baotuan; Meng Yunsheng; Liu Jian; Meng Jin; Li Weicai; Xiao Jinfeng; Chen Sencai; Du Yuhai; Huang Bin

    2006-10-01

    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)

  8. Leaching mechanisms

    Dougherty, D.R.; Colombo, P.

    1984-01-01

    Sufficient data are lacking to provide a basis for adequately assessing the long term leaching behavior of solidified low level radioactive waste forms in their disposal environment. Although the release of radioactivity from a waste form to an aqueous environment is recognized to be due to one or more mechanisms such as diffusion, dissolution, corrosion or ion exchange, the leaching mechanisms and the factors which control the leaching behavior of waste forms are not fully understood. This study will determine the prevailing mechanisms for a variety of selected LLW solidification agents which are being considered for use by defense and commercial generators and which will cover the broadest possible number of mechanisms. The investigation will proceed by the postulation of mathematical models representative of the prevailing mechanism(s) and the use of statistically designed experiments to test the actual leaching behavior of laborattory samples against the postulated representations. Maximum use of existing leach data in the literature will be made by incorporating literature results into a computerized data base along with the experimental results generated in this task

  9. Effect of uniaxially pressing ordinary Portland cement pastes containing metal hydroxides on porosity, density, and leaching

    Cheeseman, C.R.; Asavapisit, S.; Knight, J.

    1998-01-01

    Synthetic metal hydroxide wastes containing Zn and Pb have been mixed with partially hydrated cement and uniaxially pressed. The effect on porosity, pore size distribution, and bulk and skeletal densities has been characterized using mercury intrusion porosimetry. Ca(OH) 2 formation has been determined using differential thermal analysis and metal leaching has been assessed in a series of static leach tests completed on monolithic samples. Pressed solidified materials have increased density, reduced porosity, and reduced Ca(OH) 2 . They exhibit increased resistance to acid attack in terms of sample weight loss during leaching due to reduced release of alkalis. Leaching of Zn and Pb is primarily determined by pH. A peak observed in Zn leaching from pressed samples is due to the effect of changing leachate pH on the dominant Zn species present

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

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

    2016-12-15

    Terbium and rare earths recovery from fluorescent powders of exhausted lamps by acid leaching with hydrochloric acid was the objective of this study. In order to investigate the factors affecting leaching a series of experiments was performed in according to a full factorial plan with four variables and two levels (4 2 ). The factors studied were temperature, concentration of acid, pulp density and leaching time. Experimental conditions of terbium dissolution were optimized by statistical analysis. The results showed that temperature and pulp density were significant with a positive and negative effect, respectively. The empirical mathematical model deducted by experimental data demonstrated that terbium content was completely dissolved under the following conditions: 90 °C, 2 M hydrochloric acid and 5% of pulp density; while when the pulp density was 15% an extraction of 83% could be obtained at 90 °C and 5 M hydrochloric acid. Finally a flow sheet for the recovery of rare earth elements was proposed. The process was tested and simulated by commercial software for the chemical processes. The mass balance of the process was calculated: from 1 ton of initial powder it was possible to obtain around 160 kg of a concentrate of rare earths having a purity of 99%. The main rare earths elements in the final product was yttrium oxide (86.43%) following by cerium oxide (4.11%), lanthanum oxide (3.18%), europium oxide (3.08%) and terbium oxide (2.20%). The estimated total recovery of the rare earths elements was around 70% for yttrium and europium and 80% for the other rare earths. Copyright © 2016 Elsevier Ltd. All rights reserved.

  11. 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. Copyright © 2015 Elsevier Ltd. All rights reserved.

  12. Leaching process

    Heinen, H.J.; McClelland, G.E.; Lindstrom, R.E.

    1982-01-01

    A gold and uranium ore is heap leached in accordance with the process comprising initial agglomeration of fines in the feed by means of a binding agent and cyanide solution. The lixiviant comprises a compatible mixture of sodium cyanide and sodium bicarbonate

  13. Leaching process

    Heinen, H J; McClelland, G E; Lindstrom, R E

    1982-10-18

    A gold and uranium ore is heap leached in accordance with the process comprising initial agglomeration of fines in the feed by means of a binding agent and cyanide solution. The lixiviant comprises a compatible mixture of sodium cyanide and sodium bicarbonate.

  14. 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

  15. Strategies for Reduced Acid and Metalliferous Drainage by Pyrite Surface Passivation

    Gujie Qian

    2017-03-01

    Full Text Available Acid and metalliferous drainage (AMD is broadly accepted to be a major global environmental problem facing the mining industry, requiring expensive management and mitigation. A series of laboratory-scale kinetic leach column (KLC experiments, using both synthetic and natural mine wastes, were carried out to test the efficacy of our pyrite passivation strategy (developed from previous research for robust and sustainable AMD management. For the synthetic waste KLC tests, initial treatment with lime-saturated water was found to be of paramount importance for maintaining long-term circum-neutral pH, favourable for the formation and preservation of the pyrite surface passivating layer and reduced acid generation rate. Following the initial lime-saturated water treatment, minimal additional alkalinity (calcite-saturated water was required to maintain circum-neutral pH for the maintenance of pyrite surface passivation. KLC tests examining natural potentially acid forming (PAF waste, with much greater peak acidity than that of the synthetic waste, blended with lime (≈2 wt % with and without natural non-acid-forming (NAF waste covers, were carried out. The addition of lime and use of NAF covers maintained circum-neutral leachate pH up to 24 weeks. During this time, the net acidity generated was found to be significantly reduced by the overlying NAF cover. If the reduced rate of acidity production from the natural PAF waste is sustained, the addition of smaller (more economically-feasible amounts of lime, together with application of NAF wastes as covers, could be trialled as a potential cost-effective AMD mitigation strategy.

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

    Tatarková, Veronika; Hiller, Edgar; Vaculík, Marek

    2013-06-01

    Biochar addition to agricultural soils might increase the sorption of herbicides, and therefore, affect other sorption-related processes such as leaching, dissipation and toxicity for plants. In this study, the impact of wheat straw biochar on the sorption, leaching and dissipation in a soil, and toxicity for sunflower of (4-chloro-2-methylphenoxy)acetic acid (MCPA), a commonly used ionizable herbicide, was investigated. The results showed that MCPA sorption by biochar and biochar-amended soil (1.0wt% biochar) was 82 and 2.53 times higher than that by the non-amended soil, respectively. However, desorption of MCPA from biochar-amended soil was only 1.17 times lower than its desorption in non-amended soil. Biochar addition to soil reduced both MCPA leaching and dissipation. About 35% of the applied MCPA was transported through biochar-amended soil, while up to 56% was recovered in the leachates transported through non-amended soil. The half-life value of MCPA increased from 5.2d in non-amended soil to 21.5 d in biochar-amended soil. Pot experiments with sunflower (Helianthus annuus L.) grown in MCPA-free, but biochar-amended soil showed no positive effect of biochar on the growth of sunflower in comparison to the non-amended soil. However, biochar itself significantly reduced the content of photosynthetic pigments (chlorophyll a, b) in sunflower. There was no significant difference in the phytotoxic effects of MCPA on sunflowers between the biochar-amended soil and the non-amended soil. Furthermore, MCPA had no effect on the photosynthetic pigment contents in sunflower. Copyright © 2013 Elsevier Inc. All rights reserved.

  17. 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; Oliveira, P C; Costa, M C; da Costa, A M Rosa

    2014-08-15

    The recycling of platinum-group metals from wastes such as autocatalytic converters is getting growing attention due to the scarcity of these precious metals and the market pressure originated by increase of demand in current and emerging applications. Hydrometallurgical treatment of such wastes is an alternative way to the most usual pyrometallurgical processes based on smelter operations. This paper focuses on the development of a leaching process using cupric chloride as oxidising agent, in HCl media, for recovery of palladium and rhodium from a spent catalyst. The chloride media allows the adequate conditions for oxidising and solubilising the metals, as demonstrated by equilibrium calculations based on thermodynamic data. The experimental study of the leaching process revealed that Pd solubilisation is clearly easier than that of Rh. The factors temperature, time, and HCl and Cu(2+) concentrations were significant regarding Pd and Rh leaching, the latter requiring higher factor values to achieve the same results. Leaching yields of 95% Pd and 86% Rh were achieved under optimised conditions (T = 80 °C, t = 4h, [HCl] = 6M, [Cu(2+)] = 0.3M). Copyright © 2014 Elsevier B.V. All rights reserved.

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

    Thevenot, M.; Dousset, S.; Rousseaux, S.; Andreux, F.

    2008-01-01

    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

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

    Thevenot, M. [UMR 1229 Microbiologie et Geochimie des Sols, CMSE, INRA - Universite de Bourgogne, UFR des Sciences de la Terre et de l' Environnement, 6 Boulevard Gabriel, 21000 Dijon (France)], E-mail: mathieu.thevenot@u-bourgogne.fr; Dousset, S. [UMR 5561 Biogeosciences, CNRS - Universite de Bourgogne, UFR des Sciences de la Terre et de l' Environnement, 6 Boulevard Gabriel, 21000 Dijon (France); Rousseaux, S. [EA 4149 Laboratoire de Recherche en Vigne et Vin, Institut Universitaire de la Vigne et du Vin, rue Claude Ladrey, 21000 Dijon (France); Andreux, F. [UMR 1229 Microbiologie et Geochimie des Sols, CMSE, INRA - Universite de Bourgogne, UFR des Sciences de la Terre et de l' Environnement, 6 Boulevard Gabriel, 21000 Dijon (France)

    2008-05-15

    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.

  20. One-step separation by thermal treatment and cobalt acid-leaching from spent lithium-ion batteries

    Mu, Deying

    2017-10-01

    Lithium-ion batteries are extensively used in portable storage devices and automobiles, therefore the environment and resource problems caused by spent lithium ion batteries have become increasingly severe. This paper focuses on the recovery process of spent lithium cobalt oxide active material and comes up with reasonable processes and the best conditions for cobalt leaching ultimately.

  1. Early dinner reduces nocturnal gastric acidity.

    Duroux, P; Bauerfeind, P; Emde, C; Koelz, H R; Blum, A L

    1989-01-01

    This study examines whether eating food at different times has differential effects on intragastric pH. Experiments were done in 23 healthy volunteers (12 men). Intragastric acidity was monitored by ambulatory 22 hour pH-metry. Composition of meals was standardised: breakfast and lunch at 7 am and 12 noon respectively, and dinner at 6 or 9 pm, in random order. The time of going to bed and getting up was also standardised. With early dinner nocturnal pH was higher, than with late dinner (pH me...

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

    Estrada Aguilar, J.; Uriarte Hueda, A.

    1962-01-01

    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

  3. Photocatalytic properties of Co_3O_4/LiCoO_2 recycled from spent lithium-ion batteries using citric acid as leaching agent

    Santana, I.L.; Moreira, T.F.M.; Lelis, M.F.F.; Freitas, M.B.J.G.

    2017-01-01

    In this work, cobalt and lithium from the cathodes of spent lithium-ion batteries were recycled to synthesize a mixture of Co_3O_4 and LiCoO_2. The positive electrode was leached with citric acid in the green recycling. After being heated to 85 °C, the leaching solution formed a pink sol, and after being dried at 120 °C for 24 h, it formed a gel, which is a precursor material for Co_3O_4 and LiCoO_2 synthesis. A mixture of Co_3O_4 and LT-LiCoO_2 was obtained after the calcination of the precursor material at 450 °C for 3 h. The photocatalytic properties of the Co_3O_4 and LiCoO_2 were tested in the discoloration of methylene blue dye. The discoloration efficiency of methylene blue dye in the presence of Co_3O_4 and LiCoO_2 was 90% after 10 h and 100% after 24 h of heterogeneous catalysis. The contribution of this work is that it presents a means to produce valuable materials with photocatalytic properties from recycled batteries through a spent Li-ion battery recycling process without polluting the environment. - Highlights: • Synthesis a mixture of Co_3O_4/LiCoO_2 from spent Li-ion batteries. • Citric acid for leaching of the cathodes of the spent Li-ion batteries. • Co_3O_4/LiCoO_2 as catalysts in the photodegradation of the methylene blue dye.

  4. Bacterial leaching of waste uranium materials.

    Barbic, F F; Bracilović, D M; Krajincanić, B V; Lucić, J L

    1976-01-01

    The effect of ferrobacteria and thiobacteria on the leaching of waste uranium materials from which 70-80% of uranium was previously leached by classical chemical hydrometallurgical procedure has been investigated. The bacteria used are found in the ore and the mine water of Zletovska River locality, Yugoslavia. Parameters of biological leaching were examined in the laboratory. Leaching conditions were changed with the aim of increasing the amount of uranium leached. The effect of pyrite added to the waste materials before the beginning of leaching has also been examined. Uranium leaching is directly proportional to the composition and number of ferrobacteria and thiobacteria, and increased by almost twice the value obtained from the same starting materials without using bacteria. Increased sulphuric acid concentrations stimulate considerably the rate of leaching. Uranium leaching is increased up to 20% while sulphuric acid consumption is simultaneously decreased by the addition of pyrite. Uranium concentrations in starting waste materials used for leaching were extremely low (0.0278 and 0.372% U) but about 60% recovery of uranium was obtained, with relatively low consumption of sulphuric acid.

  5. Bacterial leaching of waste uranium materials

    Barbic, F.F.; Bracilovic, D.M.; Krajincanic, B.V.; Lucic, J.L.

    1976-01-01

    The effect of ferrobacteria and thiobacteria on the leaching of waste uranium materials from which 70-80% of uranium was previously leached by classical chemical hydrometallurgical procedure has been investigated. The bacteria used are found in the ore and the mine water of Zletovska River locality, Yugoslavia. Parameters of biological leaching were examined in the laboratory. Leaching conditions were changed with the aim of increasing the amount of uranium leached. The effect of pyrite added to the waste materials before the beginning of leaching has also been examined. Uranium leaching is directly proportional to the composition and number of ferrobacteria and thiobacteria, and increased by almost twice the value obtained from the same starting materials without using bacteria. Increased sulphuric acid concentrations stimulate considerably the rate of leaching. Uranium leaching is increased up to 20% while sulphuric acid consumption is simultaneously decreased by the addition of pyrite. Uranium concentrations in starting waste materials used for leaching were extremely low (0.0278 and 0.0372% U) but about 60% recovery of uranium was obtained, with relatively low consumption of sulphuric acid. (author)

  6. Remediation of Acid Mine Drainage with Sulfate Reducing Bacteria

    Hauri, James F.; Schaider, Laurel A.

    2009-01-01

    Sulfate reducing bacteria have been shown to be effective at treating acid mine drainage through sulfide production and subsequent precipitation of metal sulfides. In this laboratory experiment for undergraduate environmental chemistry courses, students design and implement a set of bioreactors to remediate acid mine drainage and explain observed…

  7. Imouraren - uranium leaching tests and specificities with analcites

    Wattinne-Morice, A.; Belieres, M.

    2010-01-01

    Imouraren is a sedimentary uranium deposit (total > 150 000 tU, average U ~ 0.08 %), located in Niger (~ 100 km from Agadez). Uranium mineralization is trapped in sandstones and is widely oxidized (uranotyle, metatuyamunite), but a part remains reduced (pitchblende, uraninite). The sandstones have a peculiar mineralogical assemblage (analcite partly chloritized) which can affect uranium recovery. Several acid heap leaching tests have been completed to determine the most suitable process parameters. Microscopic studies and XRD analysis performed on fresh ore and on leached residue highlight the complex behavior of uranium and the associated mineralogical families during the tests. (author)

  8. Deep cleaning of a metallurgical zinc leaching residue and recovery of valuable metals

    Xing, Peng; Ma, Bao-zhong; Zeng, Peng; Wang, Cheng-yan; Wang, Ling; Zhang, Yong-lu; Chen, Yong-qiang; Wang, Shuo; Wang, Qiu-yin

    2017-11-01

    Huge quantities of zinc leaching residues (ZLRs) generated from zinc production are dumped continuously around the world and pose a potential environmental threat because of their considerable amounts of entrained heavy metals (mainly lead). Most ZLRs have not been properly treated and the valuable metals in them have not yet been effectively recovered. Herein, the deep cleaning of a ZLR and recovery of valuable metals via a hydrometallurgical route were investigated. The cleaning process consists of two essential stages: acid leaching followed by calcium chloride leaching. The optimum conditions for extracting zinc, copper, and indium by acid leaching were a sulfuric acid concentration of 200 g·L-1, a liquid/solid ratio of 4:1 (mL/g), a leaching time of 2 h, and a temperature of 90°C. For lead and silver extractions, the optimum conditions were a calcium chloride concentration of 400 g·L-1, a pH value of 1.0, a leaching time of 1 h, and a temperature of 30°C. After calcium chloride leaching, silver and lead were extracted out and the lead was finally recovered as electrolytic lead by electrowinning. The anglesite phase, which poses the greatest potential environmental hazard, was removed from the ZLR after deep cleaning, thus reducing the cost of environmental management of ZLRs. The treatment of chlorine and spent electrolyte generated in the process was discussed.

  9. Heap leaching procedure for the Uranium extraction

    Shishahbore, M. R.

    2002-01-01

    Heap leaching of Uranium ores is currently in use in several countries. Before taking any decision for construction of heap in industrial scale, it is necessary to obtain the main factors that influence the heap leaching process, such as acid construction, acid solution flowrate, temperature of reaction, or size, ration of liquid to solid, permeability and suitable oxidant. To achieve the above parameters, small scale column leaching is usually recommended. In this project column leaching were carried out in 6 plexiglass column with 43.5 cm an height and 7.4 cm inner diameter. In each column closely 2.00 kg Uranium ore were leached by sulfuric acid. Leaching operation on Iranian ores from two different anomalies from the same area were investigated. In this project, six column were leached at different flowrate of eluent and effect of oxidant were investigated. Acid consumption were in the range of 60 - 144 kg per ton ore and recovery between 73.07% - 99.97%. Finally according to the results obtained, investigated that over are suitable to heap leaching technique. Al tough, to enforce of heap leaching project need to more experiments

  10. Leaching of gallium from gaiter granite, eastern desert, Egypt

    Zahran, M.A.; Mahmoud, KH.F.; Mahdy, M.A.; Abd El-Hamid, A.M.

    2006-01-01

    Preliminary leaching tests of gallium from some Egyptian granite rocks such as those of Gabal Gattar area was investigated by using 8 M HCl acid and sodium perchlorate as oxidant. To achieve the optimum leaching conditions, the factors affecting the leaching efficiency as the acid type and concentration, oxidant type and amount, leaching temperature, agitation time, solid / liquid ratio and the effect of grain size were studied. The complete chemical analysis of the collected samples was firstly carried out to determine the chemical features of the Gattarian granite. More than 97% of gallium content was leached when applying these optimum leaching conditions

  11. Experiment on bio-leaching of associated molybdenum and uranium ore

    Zheng Ying; Fan Baotuan; Liu Jian; Meng Yunsheng; Liu Chao

    2007-01-01

    Column leaching experiment results on associated molybdenum uranium ore by bacteria (T. f) are introduced. The ore are leached for 210 days using bacteria domesticated to tolerate molybdenum, the leaching of uranium is of 98% and leaching of molybdenum is of 41%. Sulphuric acid produced by bio-oxidation of sulfides in ore can meet the demand of ore leaching. (authors)

  12. Investigation of electrolyte leaching in the performance degradation of phosphoric acid-doped polybenzimidazole membrane-based high temperature fuel cells

    Jeong, Yeon Hun; Oh, Kyeongmin; Ahn, Sungha; Kim, Na Young; Byeon, Ayeong; Park, Hee-Young; Lee, So Young; Park, Hyun S.; Yoo, Sung Jong; Jang, Jong Hyun; Kim, Hyoung-Juhn; Ju, Hyunchul; Kim, Jin Young

    2017-09-01

    Precise monitoring of electrolyte leaching in high-temperature polymer electrolyte membrane fuel cell (HT-PEMFC) devices during lifetime tests is helpful in making a diagnosis of their quality changes and analyzing their electrochemical performance degradation. Here, we investigate electrolyte leaching in the performance degradation of phosphoric acid (PA)-doped polybenzimidazole (PBI) membrane-based HT-PEMFCs. We first perform quantitative analyses to measure PA leakage during cell operation by spectrophotometric means, and a higher PA leakage rate is detected when the current density is elevated in the cell. Second, long-term degradation tests under various current densities of the cells and electrochemical impedance spectroscopy (EIS) analysis are performed to examine the influence of PA loss on the membrane and electrodes during cell performance degradation. The combined results indicate that PA leakage affect cell performance durability, mostly due to an increase in charge transfer resistance and a decrease in the electrochemical surface area (ECSA) of the electrodes. Additionally, a three-dimensional (3-D) HT-PEMFC model is applied to a real-scale experimental cell, and is successfully validated against the polarization curves measured during various long-term experiments. The simulation results highlight that the PA loss from the cathode catalyst layer (CL) is a significant contributor to overall performance degradation.

  13. Economic leaching at Roessing Uranium Limited

    Johnson, C.C.

    1990-01-01

    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

  14. Pressure leaching of chalcopyrite concentrate

    Aleksei, Kritskii; Kirill, Karimov; Stanislav, Naboichenko

    2018-05-01

    The results of chalcopyrite concentrate processing using low-temperature and high-temperature sulfuric acid pressure leaching are presented. A material of the following composition was used, 21.5 Cu, 0.1 Zn, 0.05 Pb, 0.04 Ni, 26.59 S, 24.52 Fe, 16.28 SiO2 (in wt.%). The influence of technological parameters on the degree of copper and iron extraction into the leach solution was studied in the wide range of values. The following conditions were suggested as the optimal for the high-temperature pressure leaching: t = 190 °C, PO2 = 0.5 MPa, CH2SO4 = 15 g/L, L:S = 6:1. At the mentioned parameters, it is possible to extract at least 98% Cu from concentrate into the leaching solution during 100 minutes. The following conditions were suggested as optimal for the low-temperature pressure leaching: t = 105 °C, PO2 = 1.3-1.5 MPa, CH2SO4 = 90 g/L, L:S = 10:1. At the mentioned parameters, it is possible to extract up to 83% Cu from the concentrate into the leach solution during 300-360 minutes.

  15. Procedure for reducing hydrogen ion concentration in acidic anion eluate

    Parobek, P.; Baloun, S.; Plevac, S.

    1992-01-01

    A procedure is suggested for reducing the concentration of hydrogen ions in the acidic anionic eluate formed during the separation of uranium. The procedure involves anex elution, precipitation, filtration, precipitate rinsing, and anex rinsing. The procedure is included in the uranium elution process and requires at least one ion exchanger column and at least one tank in the continuous or discontinuous mode. Sparing the neutralizing agent by reducing the hydrogen ion concentration in the acidic anionic eluate is a major asset of this procedure. (Z.S.). 1 fig

  16. Uranium extraction history using pressure leaching

    Fraser, K.S.; Thomas, K.G.

    2010-01-01

    Over the past 60 years of uranium process development only a few commercial uranium plants have adopted a pressure leaching process in their flowsheet. The selection of acid versus alkaline pressure leaching is related to the uranium and gangue mineralogy. Tetravalent (U"+"4) uranium has to be oxidized to hexavalent (U"+"6) uranium to be soluble. Refractory tetravalent uranium requires higher temperature and pressure, as practised in pressure leaching, for conversation to soluble hexavalent uranium. This paper chronicles the history of these uranium pressure leaching facilities over the past 60 years, with specific details of each design and operation. (author)

  17. A new Leaching System, Sheta Extractor

    Sheta, M.E.

    2008-01-01

    Moving of crushed solid ores against leaching solution in a continuous countercurrent arises a true technical problem. This invented system introduces a practical solution for such problem. Inside the system, the crushed ore is driving against gravity, whereas the leaching solution moves in the opposite direction. Contact between the two phases occurs with gentle stirring. After contact, discharging of the processed phases takes place automatically out the system. The system was investigated for uranium leaching from a coarse grained fraction (+2 --- -- -30 mm) of uranium mineralized granite sample. Uranium leaching percent reached to nearly 50% using sulfuric acid

  18. Novel Omega-3 Fatty Acid Epoxygenase Metabolite Reduces Kidney Fibrosis

    Sharma, Amit; Khan, Md. Abdul Hye; Levick, Scott P.; Lee, Kin Sing Stephen; Hammock, Bruce D.; Imig, John D.

    2016-01-01

    Cytochrome P450 (CYP) monooxygenases epoxidize the omega-3 polyunsaturated fatty acid (PUFA) docosahexaenoic acid into novel epoxydocosapentaenoic acids (EDPs) that have multiple biological actions. The present study determined the ability of the most abundant EDP regioisomer, 19,20-EDP to reduce kidney injury in an experimental unilateral ureteral obstruction (UUO) renal fibrosis mouse model. Mice with UUO developed kidney tubular injury and interstitial fibrosis. UUO mice had elevated kidney hydroxyproline content and five-times greater collagen positive fibrotic area than sham control mice. 19,20-EDP treatment to UUO mice for 10 days reduced renal fibrosis with a 40%–50% reduction in collagen positive area and hydroxyproline content. There was a six-fold increase in kidney α-smooth muscle actin (α-SMA) positive area in UUO mice compared to sham control mice, and 19,20-EDP treatment to UUO mice decreased α-SMA immunopositive area by 60%. UUO mice demonstrated renal epithelial-to-mesenchymal transition (EMT) with reduced expression of the epithelial marker E-cadherin and elevated expression of multiple mesenchymal markers (FSP-1, α-SMA, and desmin). Interestingly, 19,20-EDP treatment reduced renal EMT in UUO by decreasing mesenchymal and increasing epithelial marker expression. Overall, we demonstrate that a novel omega-3 fatty acid metabolite 19,20-EDP, prevents UUO-induced renal fibrosis in mice by reducing renal EMT. PMID:27213332

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

    Formiga, Thiago S.; Morais, Carlos A.; Gomiero, Luiz A.

    2011-01-01

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

  20. Leaching and geochemical behavior of fired bricks containing coal wastes.

    Taha, Yassine; Benzaazoua, Mostafa; Edahbi, Mohamed; Mansori, Mohammed; Hakkou, Rachid

    2018-03-01

    High amounts of mine wastes are continuously produced by the mining industry all over the world. Recycling possibility of some wastes in fired brick making has been investigated and showed promising results. However, little attention is given to the leaching behavior of mine wastes based fired bricks. The objective of this paper is to evaluate the geochemical behavior of fired bricks containing different types of coal wastes. The leachates were analyzed for their concentration of As, Ba, Cd, Co, Cr, Cu, Mo, Ni, Pb, Zn and sulfates using different leaching tests; namely Tank Leaching tests (NEN 7375), Toxicity Characteristic Leaching Procedure (TCLP) and pH dependence test (EPA, 1313). The results showed that the release of constituents of potential interest was highly reduced after thermal treatment and were immobilized within the glassy matrix of the fired bricks. Moreover, it was also highlighted that the final pH of all fired samples changed and stabilized around 8-8.5 when the initial pH of leaching solution was in the range 2.5-11.5. The release of heavy metals and metalloids (As) tended to decrease with the increase of pH from acidic to alkaline solutions while Mo displayed a different trend. Copyright © 2017 Elsevier Ltd. All rights reserved.

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

    Hussein El-Sayed, M

    1984-07-01

    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 P/sub 2/O/sub 5/) leaching efficiency were studied.

  2. Inhibition of fatty acid metabolism reduces human myeloma cells proliferation.

    José Manuel Tirado-Vélez

    Full Text Available Multiple myeloma is a haematological malignancy characterized by the clonal proliferation of plasma cells. It has been proposed that targeting cancer cell metabolism would provide a new selective anticancer therapeutic strategy. In this work, we tested the hypothesis that inhibition of β-oxidation and de novo fatty acid synthesis would reduce cell proliferation in human myeloma cells. We evaluated the effect of etomoxir and orlistat on fatty acid metabolism, glucose metabolism, cell cycle distribution, proliferation, cell death and expression of G1/S phase regulatory proteins in myeloma cells. Etomoxir and orlistat inhibited β-oxidation and de novo fatty acid synthesis respectively in myeloma cells, without altering significantly glucose metabolism. These effects were associated with reduced cell viability and cell cycle arrest in G0/G1. Specifically, etomoxir and orlistat reduced by 40-70% myeloma cells proliferation. The combination of etomoxir and orlistat resulted in an additive inhibitory effect on cell proliferation. Orlistat induced apoptosis and sensitized RPMI-8226 cells to apoptosis induction by bortezomib, whereas apoptosis was not altered by etomoxir. Finally, the inhibitory effect of both drugs on cell proliferation was associated with reduced p21 protein levels and phosphorylation levels of retinoblastoma protein. In conclusion, inhibition of fatty acid metabolism represents a potential therapeutic approach to treat human multiple myeloma.

  3. The reducibility of sulphuric acid and sulphate in aqueous solution

    Grauer, R.

    1991-07-01

    In connection with the Swedish project for final storage of spent fuel elements it was necessary to assess whether dissolved sulphate can corrode the copper canister. A simple reaction between copper and sulphate is thermodynamically impossible, but copper can react to give copper sulphide if an additional electron donor such as iron(II) is available. The problem was extended to the more general question of the reducibility of sulphur(VI) in dilute aqueous solution. Chemical reduction of sulphate does not take place in dilute solution at temperatures below 100 o C. In experiments on the reduction of sulphates under hydrothermal conditions a reaction only takes place at temperatures above 275-300 o C. The oxidising action of sulphuric acid on metals becomes perceptible only at acid concentrations over 45-50%. In experiments on the cathodic reduction of 74% sulphuric acid the formation of hydrogen sulphide and elementary sulphur starts, depending on the current density, at 50-130 o C, and polarographic measurements suggest that the reducible species is not the hydrogen sulphate ion but molecular sulphuric acid. The resistance of copper to oxygen-free sulphuric acid up to a concentration of 60% is well-known. Numerous processes in industrial electrochemistry take place in sulphuric acid or sulphate electrolytes. The reversible metal/metal-sulphate electrodes of lead and cadmium are unstable relative to the corresponding metal sulphides. Nevertheless the reversible lead sulphate electrode does not fail from sulphide formation. All these facts confirm that sulphur(VI) in dilute solution is completely inert towards chemical reducing agents and also to cathodic reduction. Thus corrosion of copper by sulphate under final-storage conditions and in the absence of sulphate reducing bacteria can be almost certainly be ruled out. (author) 5 figs., 85 refs

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

    Oudenhoven, Stijn; van der Ham, Aloysius G.J.; van den Berg, Henderikus; Westerhof, Roel Johannes Maria; Kersten, Sascha R.A.

    2016-01-01

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

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

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

    1995-07-01

    The focus of this research was to evaluate chemical leaching as a technique to treat soils, sediments, and glass contaminated with either elemental mercury or a combination of several mercury species. Potassium iodide/iodine solutions were investigated as chemical leaching agents for contaminated soils and sediments. Clean, synthetic soil material and surrogate storm sewer sediments contaminated with mercury were treated with KI/I 2 solutions. It was observed that these leaching solutions could reduce the mercury concentration in soil and sediments by 99.8%. Evaluation of selected posttreatment sediment samples revealed that leachable mercury levels in the treated solids exceeded RCRA requirements. The results of these studies suggest that KI/I 2 leaching is a treatment process that can be used to remove large quantities of mercury from contaminated soils and sediments and may be the only treatment required if treatment goals are established on Hg residual concentrations in solid matrices. Fluorescent bulbs were used to simulate mercury contaminated glass mixed waste. To achieve mercury contamination levels similar to those found in larger bulbs such as those used in DOE facilities a small amount of Hg was added to the crushed bulbs. The most effective agents for leaching mercury from the crushed fluorescent bulbs were KI/I 2 , NaOCl, and NaBr + acid. Radionuclide surrogates were added to both the EPA synthetic soil material and the crushed fluorescent bulbs to determine the fate of radionuclides following chemical leaching with the leaching agents determined to be the most promising. These experiments revealed that although over 98% of the dosed mercury solubilized and was found in the leaching solution, no Cerium was measured in the posttreatment leaching solution. This finding suggest that Uranium, for which Ce was used as a surrogate, would not solubilize during leaching of mercury contaminated soil or glass

  6. Some factors affecting agitation leach test during in-situ leaching of uranium

    Liao Wensheng; Jiang Yan; Wang Limin; Shi Zhenfeng; Zhao Qiaofu; MARMAR

    2014-01-01

    The agitation leaching test is one of the most fundamental research works in in-situ leaching of uranium. Some factors affecting the test results were analyzed including stirring, leaching time, oxidizer used in alkaline leach, washing solution, the amount and size of ore samples. The results indicate that stirring can enhance diffusion velocity. The leach time l or 2 days is suitable for the samples containing accessible uranium and low acid consumption minerals; whereas 3 or 4 days for those containing refractory ore to leach and slowly acid consuming minerals. For the oxidizer used in alkaline leach, potassium permanganate is better than hydrogen peroxide. Recovery calculated by the leach solution can be directly obtained by its uranium level and the original volume of lixiviant without analyzing and calculating the washing solution. The appropriate amount and size of ore samples for the agitation leaching test are 60 g and <1 mm. By controlling the above factors, the agitation leach test can improve the applicability of the different ore samples and give the more reliable data. (authors)

  7. Separation and Precipitation of Nickel from Acidic Sulfate Leaching Solution of Molybdenum-Nickel Black Shale by Potassium Nickel Sulfate Hexahydrate Crystallization

    Deng, Zhigan; Wei, Chang; Fan, Gang; Li, Xingbin; Li, Minting; Li, Cunxiong

    2018-02-01

    Nickel was separated and precipitated with potassium nickel sulfate hexahydrate [K2Ni(SO4)2·6H2O] from acidic sulfate solution, a leach solution from molybdenum-nickel black shale. The effects of the potassium sulfate (K2SO4) concentration, crystallization temperature, solution pH, and crystallization time on nickel(II) recovery and iron(III) precipitation were investigated, revealing that nickel and iron were separated effectively. The optimum parameters were K2SO4 concentration of 200 g/L, crystallization temperature of 10°C, solution pH of 0.5, and crystallization time of 24 h. Under these conditions, 97.6% nickel(II) was recovered as K2Ni(SO4)2·6H2O crystals while only 2.0% of the total iron(III) was precipitated. After recrystallization, 98.4% pure K2Ni(SO4)2·6H2O crystals were obtained in the solids. The mother liquor was purified by hydrolysis-precipitation followed by cooling, and more than 99.0% K2SO4 could be crystallized. A process flowsheet was developed to separate iron(III) and nickel(II) from acidic-sulfate solution.

  8. Proton pump inhibitors reduce the size and acidity of the acid pocket in the stomach.

    Rohof, Wout O; Bennink, Roelof J; Boeckxstaens, Guy E

    2014-07-01

    The gastric acid pocket is believed to be the reservoir from which acid reflux events originate. Little is known about how changes in position, size, and acidity of the acid pocket contribute to the therapeutic effect of proton pump inhibitors (PPIs) in patients with gastroesophageal reflux disease (GERD). Thirty-six patients with GERD (18 not taking PPIs, 18 taking PPIs; 19 men; age, 55 ± 2.1 y) were analyzed by concurrent high-resolution manometry and pH-impedance monitoring after a standardized meal. The acid pocket was visualized using scintigraphy after intravenous administration of (99m)technetium-pertechnetate. The size of the acid pocket was measured and its position was determined, relative to the diaphragm, using radionuclide markers on a high-resolution manometry catheter. At the end of the study, the acid pocket was aspirated, and its pH level was measured. The number of reflux episodes was comparable between patients on and off PPIs, but the number of acid reflux episodes was reduced significantly in patients on PPIs. In patients on PPIs, the acid pocket was smaller and more frequently located below the diaphragm. The mean pH of the acid pocket was significantly lower in patients not taking PPIs (n = 6) than in those who were (n = 16) (0.9; range, 0.7-1.2 vs 4.0; range, 1.6-5.9; P pH of acid pockets correlated significantly with the lowest pH values measured for refluxate (r = 0.72; P < .01). Based on analyses of acid pockets in patients with GERD, the acid pocket appears to be a reservoir from which reflux occurs when patients are receiving PPIs. PPIs might affect the size, acidity, or position of the acid pocket, which contributes to the efficacy in patients with GERD. Copyright © 2014 AGA Institute. Published by Elsevier Inc. All rights reserved.

  9. Leaching of nuclear power reactor wastes forms

    Endo, L.S.; Villalobos, J.P.; Miyamoto, H.

    1986-01-01

    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) [pt

  10. Bacterial leaching of uranium ores - a review

    Lowson, R.T.

    1975-11-01

    The bacterial leaching of uranium ores involves the bacterially catalysed oxidation of associated pyrite to sulphuric acid and Fe 3+ by autotrophic bacteria and the leaching of the uranium by the resulting acidic, oxidising solution. Industrial application has been limited to Thiobacillus thiooxidans and Thiobacillus ferrooxidans at pH 2 to 3, and examples of these are described. The bacterial catalysis can be improved with nutrients or prevented with poisons. The kinetics of leaching are controlled by the bed depth, particle size, percolation rate, mineralogy and temperature. Current work is aimed at quantitatively defining the parameters controlling the kinetics and extending the method to alkaline conditions with other autotrophic bacteria. (author)

  11. Reduced humic acid nanosheets and its uses as nanofiller

    Duraia, El-shazly M.; Henderson, B.; Beall, Gary W.

    2015-10-01

    Leonardite is highly oxidized form of lignite coal and contains a number of carboxyl groups around the edges of a graphene-like core. A novel approach has been developed to synthesize graphene oxide-like nanosheets in large scale utilizing leonardite as a starting material. Humic acid extracted from leonardite has been reduced by performing a high pressure catalytic hydrogenation. The reaction was carried out inside a high pressure stirred reactor at 150 °C and 750 psi (~5.2×106 Pa). Morphology of the as-synthesized samples showed porous platy particles and EDAX analysis indicates the carbon and oxygen atomic ratios as 96:4-97:3%. The as-synthesized material has been used as nanofiller in polyurethane. The reduced humic acid-polyurethane nanocomposite showed over 250% increase of Young's modulus. This new approach provides a low cost and scalable source for graphene oxide-like nanosheets in nanocomposite applications.

  12. Taoshan uranium ore fields in situ blasting heap leaching rate influence factors to investigate

    Xie Wangnan; Dong Chunming

    2014-01-01

    Taoshan ore field ore in situ blasting heap leaching out build industrial test and production process, stope leaching rate and leaching cycle is large than that, after analysis, blasting method and cloth liquid way is to affect leaching rate and leaching cycle of the main factors. This paper holds that as far as possible using stratified deep hole blasting of squeezing up ways to reduce the building pile of in-situ leaching ore block rate; Adopting effective cloth tube way, increase the leaching agent and ore contact comprehensive; Introduction of bacterial leaching, and other means to improve leaching rate, shorten production cycle, etc to solve it. (authors)

  13. Improvements on heap leaching process for a refractory uranium ore and yellow cake precipitation process

    Feng Jianke

    2013-01-01

    Some problems such as formed harden matrix, ore heap compaction, poor permeability, and agglomeration of absorption resin occur during extracting uranium from a refractory uranium ore by heap leaching process. After some measures were taken, i.e. spraying a new ore heap by low concentration acid, two or more ore heaps in series leaching, turning ores in ore heap, the permeability was improved, acid consumption was reduced. Through precipitate circulation and aging, the yellow cake slurry in amorphous or microlite form was transformed to crystal precipitate, thus uranium content in yellow cake was improved, and water content in yellow cake was lowered with good economic benefits. (author)

  14. Impact of chemical leaching on permeability and cadmium removal from fine-grained soils.

    Lin, Zhongbing; Zhang, Renduo; Huang, Shuang; Wang, Kang

    2017-08-01

    The aim of this study was to investigate the influence of chemical leaching on permeability and Cd removal from fine-grained polluted soils. Column leaching experiments were conducted using two types of soils (i.e., artificially Cd-polluted loam and historically polluted silty loam). Chemical agents of CaCl 2 , FeCl 3 , citric acid, EDTA, rhamnolipid, and deionized water were used to leach Cd from the soils. Results showed that organic agents reduced permeability of both soils, and FeCl 3 reduced permeability of loam soil, compared with inorganic agents and deionized water. Entrapment and deposition of colloids generated from the organic agents and FeCl 3 treatments reduced the soil permeability. The peak Cd effluence from the artificially polluted loam columns was retarded. For the artificially polluted soils treated with EDTA and the historically polluted soils with FeCl 3 , Cd precipitates were observed at the bottom after chemical leaching. When Cd was associated with large colloid particles, the reduction of soil permeability caused Cd accumulation in deeper soil. In addition, the slow process of disintegration of soil clay during chemical leaching might result in the retardation of peak Cd effluence. These results suggest the need for caution when using chemical-leaching agents for Cd removal in fine-grained soils.

  15. Analysis of factors affecting the effect of stope leaching

    Xie Wangnan; Dong Chunming

    2014-01-01

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

  16. Leaching kinetics of cobalt from the scraps of spent aerospace magnetic materials.

    Zhou, Xuejiao; Chen, Yongli; Yin, Jianguo; Xia, Wentang; Yuan, Xiaoli; Xiang, Xiaoyan

    2018-06-01

    Based on physicochemical properties of the scraps of spent aerospace magnetic materials, a roasting - magnetic separation followed by sulfuric acid leaching process was proposed to extract cobalt. Roasting was performed at 500 °C to remove organic impurity. Non-magnetic impurities were reduced by magnetic separation and then the raw material was sieved into desired particle sizes. Acid leaching was carried out to extract cobalt from the scraps and experimental parameters included agitation speed, particle size, initial concentration of sulfuric acid and temperature. Agitation speed higher than 300 r/min had a relatively small impact on the cobalt extraction. As the particle size reduced, the content of cobalt in the raw material decreases and the extraction of cobalt by acid leaching increased at first and decreased afterwards. Raising the initial concentration of sulfuric acid and temperature contributed to improve the cobalt extraction and the influence of temperature was more remarkable. SEM image revealed that the spent aerospace magnetic materials mainly existed in the sliced strip flake with a loose surface and porous structure. Under the experimental condition, the leaching rate of cobalt from the scraps in sulfuric acid solution could be expressed as ln(-ln(1 - α)) = lnk + nlnt. The apparent activation energy was found to be 38.33 kJ/mol and it was mainly controlled by the surface chemical reaction. Copyright © 2018 Elsevier Ltd. All rights reserved.

  17. Leaching of metals from soil contaminated by mining activities.

    Yukselen, M A; Alpaslan, B

    2001-10-12

    Stabilization/solidification (s/s) is one of the most effective methods of dealing with heavy metal contaminated sites. The ability of lime and cement stabilization to immobilize Pb, Cu and Fe contained in a contaminated soil originating from an old mining and smelting area located along the Mediterranean Sea shore in northern Cyprus was investigated. The stabilization was evaluated by applying leaching tests. A series of tests were conducted to optimize the additive soil ratio for the best immobilization process. Additive/soil=1/15 (m/m) ratio was found to be the optimum for both lime and cement. Application of the US EPA toxicity characteristic leaching procedure (TCLP) on the soil samples treated with lime at additive/soil=1/15 (m/m) mixing ratios showed that Cu and Fe solubility was reduced at 94 and 90%, respectively. The results of cement treatment using the same ratio, reduced the solubility 48 and 71% for Cu and Fe, respectively. The Pb solubility was found to be below the regulatory limit of 5mg/l so no additive treatment was needed. The optimum additive/soil amount (1/15) was selected for more detailed column studies, that were carried out in the acidic pH range. According to the results of column leaching tests, it was found that, the degree of heavy metal leaching is highly dependent on pH.

  18. Reduced carbon sequestration potential of biochar in acidic soil.

    Sheng, Yaqi; Zhan, Yu; Zhu, Lizhong

    2016-12-01

    Biochar application in soil has been proposed as a promising method for carbon sequestration. While factors affecting its carbon sequestration potential have been widely investigated, the number of studies on the effect of soil pH is limited. To investigate the carbon sequestration potential of biochar across a series of soil pH levels, the total carbon emission, CO 2 release from inorganic carbon, and phospholipid fatty acids (PLFAs) of six soils with various pH levels were compared after the addition of straw biochar produced at different pyrolysis temperatures. The results show that the acidic soils released more CO 2 (1.5-3.5 times higher than the control) after the application of biochar compared with neutral and alkaline soils. The degradation of both native soil organic carbon (SOC) and biochar were accelerated. More inorganic CO 2 release in acidic soil contributed to the increased degradation of biochar. Higher proportion of gram-positive bacteria in acidic soil (25%-36%) was responsible for the enhanced biochar degradation and simultaneously co-metabolism of SOC. In addition, lower substrate limitation for bacteria, indicated by higher C-O stretching after the biochar application in the acidic soil, also caused more CO 2 release. In addition to the soil pH, other factors such as clay contents and experimental duration also affected the phsico-chemical and biotic processes of SOC dynamics. Gram-negative/gram-positive bacteria ratio was found to be negatively related to priming effects, and suggested to serve as an indicator for priming effect. In general, the carbon sequestration potential of rice-straw biochar in soil reduced along with the decrease of soil pH especially in a short-term. Given wide spread of acidic soils in China, carbon sequestration potential of biochar may be overestimated without taking into account the impact of soil pH. Copyright © 2016 Elsevier B.V. All rights reserved.

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

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

    1982-01-01

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

  20. Copper leaching of MSWI bottom ash co-disposed with refuse: effect of short-term accelerated weathering.

    Su, Lianghu; Guo, Guangzhai; Shi, Xinlong; Zuo, Minyu; Niu, Dongjie; Zhao, Aihua; Zhao, Youcai

    2013-06-01

    Co-disposal of refuse with municipal solid waste incinerator (MSWI) bottom ash (IBA) either multi-layered as landfill cover or mixed with refuse could pose additional risk to the environment because of enhanced leaching of heavy metals, especially Cu. This study applied short-term accelerated weathering to IBA, and monitored the mineralogical and chemical properties of IBA during the weathering process. Cu extractability of the weathered IBA was then evaluated using standard leaching protocols (i.e. SPLP and TCLP) and co-disposal leaching procedure. The results showed that weathering had little or no beneficial effect on Cu leaching in SPLP and TCLP, which can be explained by the adsorption and complexation of Cu with DOM. However, the Cu leaching of weathered IBA was reduced significantly when situated in fresh simulated landfill leachate. This was attributed to weakening Cu complexation with fulvic acid or hydrophilic fractions and/or intensifying Cu absorption to neoformed hydr(oxide) minerals in weathered IBA. The amount of total leaching Cu and Cu in free or labile complex fraction (the fraction with the highest mobility and bio-toxicity) of the 408-h weathered IBA were remarkably decreased by 86.3% and 97.6% in the 15-day co-disposal leaching test. Accelerated weathering of IBA may be an effective pretreatment method to decrease Cu leaching prior to its co-disposal with refuse. Copyright © 2013 Elsevier Ltd. All rights reserved.

  1. Comparative study of ageing, heat treatment and accelerated carbonation for stabilization of municipal solid waste incineration bottom ash in view of reducing regulated heavy metal/metalloid leaching.

    Santos, Rafael M; Mertens, Gilles; Salman, Muhammad; Cizer, Özlem; Van Gerven, Tom

    2013-10-15

    This study compared the performance of four different approaches for stabilization of regulated heavy metal and metalloid leaching from municipal solid waste incineration bottom ash (MSWI-BA): (i) short term (three months) heap ageing, (ii) heat treatment, (iii) accelerated moist carbonation, and (iv) accelerated pressurized slurry carbonation. Two distinct types of MSWI-BA were tested in this study: one originating from a moving-grate furnace incineration operation treating exclusively household refuse (sample B), and another originating from a fluid-bed furnace incineration operation that treats a mixture of household and light industrial wastes (sample F). The most abundant elements in the ashes were Si (20-27 wt.%) and Ca (16-19 wt.%), followed by significant quantities of Fe, Al, Na, S, K, Mg, Ti, and Cl. The main crystalline substances present in the fresh ashes were Quartz, Calcite, Apatite, Anhydrite and Gehlenite, while the amorphous fraction ranged from 56 to 73 wt.%. The leaching values of all samples were compared to the Flemish (NEN 7343) and the Walloon (DIN 38414) regulations from Belgium. Batch leaching of the fresh ashes at natural pH showed that seven elements exceeded at least one regulatory limit (Ba, Cr, Cu, Mo, Pb, Se and Zn), and that both ashes had excess basicity (pH > 12). Accelerated carbonation achieved significant reduction in ash basicity (9.3-9.9); lower than ageing (10.5-12.2) and heat treatment (11.1-12.1). For sample B, there was little distinction between the leaching results of ageing and accelerated carbonation with respect to regulatory limits; however carbonation achieved comparatively lower leaching levels. Heat treatment was especially detrimental to the leaching of Cr. For sample F, ageing was ineffective and heat treatment had marginally better results, while accelerated carbonation delivered the most effective performance, with slurry carbonation meeting all DIN limits. Slurry carbonation was deemed the most

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

    Bechtold, D.B.

    1998-01-01

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

  3. Docosahexaenoic Acid Reduces Amyloid β Production via Multiple Pleiotropic Mechanisms*

    Grimm, Marcus O. W.; Kuchenbecker, Johanna; Grösgen, Sven; Burg, Verena K.; Hundsdörfer, Benjamin; Rothhaar, Tatjana L.; Friess, Petra; de Wilde, Martijn C.; Broersen, Laus M.; Penke, Botond; Péter, Mária; Vígh, László; Grimm, Heike S.; Hartmann, Tobias

    2011-01-01

    Alzheimer disease is characterized by accumulation of the β-amyloid peptide (Aβ) generated by β- and γ-secretase processing of the amyloid precursor protein (APP). The intake of the polyunsaturated fatty acid docosahexaenoic acid (DHA) has been associated with decreased amyloid deposition and a reduced risk in Alzheimer disease in several epidemiological trials; however, the exact underlying molecular mechanism remains to be elucidated. Here, we systematically investigate the effect of DHA on amyloidogenic and nonamyloidogenic APP processing and the potential cross-links to cholesterol metabolism in vivo and in vitro. DHA reduces amyloidogenic processing by decreasing β- and γ-secretase activity, whereas the expression and protein levels of BACE1 and presenilin1 remain unchanged. In addition, DHA increases protein stability of α-secretase resulting in increased nonamyloidogenic processing. Besides the known effect of DHA to decrease cholesterol de novo synthesis, we found cholesterol distribution in plasma membrane to be altered. In the presence of DHA, cholesterol shifts from raft to non-raft domains, and this is accompanied by a shift in γ-secretase activity and presenilin1 protein levels. Taken together, DHA directs amyloidogenic processing of APP toward nonamyloidogenic processing, effectively reducing Aβ release. DHA has a typical pleiotropic effect; DHA-mediated Aβ reduction is not the consequence of a single major mechanism but is the result of combined multiple effects. PMID:21324907

  4. Oral Tranexamic Acid Reduces Transfusions in Total Knee Arthroplasty.

    Perreault, Roger E; Fournier, Christine A; Mattingly, David A; Junghans, Richard P; Talmo, Carl T

    2017-10-01

    Tranexamic acid (TXA) reduces intraoperative blood loss and transfusions in patients undergoing total knee arthroplasty. Although numerous studies demonstrate the efficacy of intravenous and topical TXA in these patients, few demonstrate the effectiveness and appropriate dosing recommendations of oral formulations. A retrospective cohort study was performed to evaluate differences in transfusion requirements in patients undergoing primary unilateral total knee arthroplasty with either no TXA (n = 866), a single-dose of oral TXA (n = 157), or both preoperative and postoperative oral TXA (n = 1049). Secondary outcomes included postoperative hemoglobin drop, total units transfused, length of stay, drain output, and cell salvage volume. Transfusion rates decreased from 15.4% in the no-oral tranexamic acid (OTA) group to 9.6% in the single-dose OTA group (P < .001) and 7% in the 2-dose group (P < .001), with no difference in transfusion rates between the single- and 2-dose groups (P = .390). In addition, postoperative hemoglobin drop was reduced from 4.2 g/dL in the no-OTA group to 3.5 g/dL in the single-dose group (P < .01) and to 3.4 g/dL in the 2-dose group (P < .01), without a difference between the single- and 2-dose groups (P = .233). OTA reduces transfusions, with greater ease of administration and improved cost-effectiveness relative to other forms of delivery. Copyright © 2017 Elsevier Inc. All rights reserved.

  5. The use of lactic acid bacteria to reduce mercury bioaccessibility.

    Jadán-Piedra, C; Alcántara, C; Monedero, V; Zúñiga, M; Vélez, D; Devesa, V

    2017-08-01

    Mercury in food is present in either inorganic [Hg(II)] or methylmercury (CH 3 Hg) form. Intestinal absorption of mercury is influenced by interactions with other food components. The use of dietary components to reduce mercury bioavailability has been previously proposed. The aim of this work is to explore the use of lactic acid bacteria to reduce the amount of mercury solubilized after gastrointestinal digestion and available for absorption (bioaccessibility). Ten strains were tested by addition to aqueous solutions containing Hg(II) or CH 3 Hg, or to food samples, and submission of the mixtures to gastrointestinal digestion. All of the strains assayed reduce the soluble fraction from standards of mercury species under gastrointestinal digestion conditions (72-98%). However their effectiveness is lower in food, and reductions in bioaccessibility are only observed with mushrooms (⩽68%). It is hypothesized that bioaccessible mercury in seafood forms part of complexes that do not interact with lactic acid bacteria. Copyright © 2017 Elsevier Ltd. All rights reserved.

  6. 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. Copyright © 2015 Elsevier Ltd. All rights reserved.

  7. Pilot test of bacterial percolation leaching at Fuzhou uranium mine

    Fan Baotuan; Liu Jian; Jiang Yngqiong; Cai Chunhui; Jiang Lang; Zhou Renhua; Tong Changning; Zhang Hongli

    2006-01-01

    Total 18 t uranium ores of Fuzhou Uranium Mine packed in three or four columns in series were leached by bacterial percolation. The results show that without adding any other chemical oxidant such as sodium chlorate, the leaching rate measured by residue is 91.45%-94.48%, leaching time is 50-60 d, acid consumption is 6.17%-7.75%, and residue grade is 0.0149%-0.0208%. Compared with conventional percolation leaching process, the leaching rate is improved by 3%, leaching time is shorted by 26%, and acid consumption is saved by 34%. Accumulation pattern of ΣFe and F - in the process of leaching is discussed. Influence of F - on bacterial growth, regeneration of barren solution as well as correlative techniques are reviewed. (authors)

  8. Combined oxidative leaching and electrowinning process for mercury recovery from spent fluorescent lamps.

    Ozgur, Cihan; Coskun, Sezen; Akcil, Ata; Beyhan, Mehmet; Üncü, Ismail Serkan; Civelekoglu, Gokhan

    2016-11-01

    In this paper, oxidative leaching and electrowinnig processes were performed to recovery of mercury from spent tubular fluorescent lamps. Hypochlorite was found to be effectively used for the leaching of mercury to the solution. Mercury could be leached with an efficiency of 96% using 0.5M/0.2M NaOCl/NaCl reagents at 50°C and pH 7.5 for 2-h. Electrowinning process was conducted on the filtered leaching solutions and over the 81% of mercury was recovered at the graphite electrode using citric acid as a reducing agent. The optimal process conditions were observed as a 6A current intensity, 30g/L of reducing agent concentration, 120min. electrolysis time and pH of 7 at the room temperature. It was found that current intensity and citric acid amount had positive effect for mercury reduction. Recovery of mercury in its elemental form was confirmed by SEM/EDX. Oxidative leaching with NaOCl/NaCl reagent was followed by electrowinning process can be effectively used for the recovery of mercury from spent fluorescent lamps. Copyright © 2016 Elsevier Ltd. All rights reserved.

  9. LEACHING BOUNDARY IN CEMENT-BASED WASTE FORMS

    Cement-based fixation systems are among the most commonly employed stabilization/solidification techniques. These cement haste mixtures, however, are vulnerable to ardic leaching solutions. Leaching of cement-based waste forms in acetic acid solutions with different acidic streng...

  10. Static leaching of uraniferous shales on open areas

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

    1973-01-01

    This report describes the tests on acid heap leaching with conventional (1.400 ppm U 3 O 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)

  11. Optimizing conditions for an accelerated leach test

    Pietrzak, R.F.; Fuhrmann, M.; Heiser, J.; Franz, E.M.; Colombo, P.

    1988-01-01

    An accelerated leach test for low-level radioactive waste forms is being developed to provide, in a short time, data that can be extrapolated to long time periods. The approach is to provide experimental conditions that will accelerate leaching without changing the dominant release mechanism. Experimental efforts have focused on combining individual factors that have been observed to accelerate leaching. These include elevated temperature, increased leachant volume, and reduced specimen size. The response of diffusion coefficients to various acceleration factors have been evaluated and provide information on experimental parameters that need to be optimized to increase leach rates. Preliminary modeling using a diffusion mechanism (allowing for depletion) of a finite cylinder geometry indicates that during early portions of experiments (daily sampling intervals), leaching is diffusion controlled and more rapid than later in the same experiments (weekly or greater sampling intervals). For cement waste forms, this reduction in rate may be partially controlled by changes in physical structure and chemistry (sometimes related to environmental influences such as CO 2 ), but it is more likely associated with the duration of the sampling interval. By using a combination of mathematical modeling and by experimentally investigating various leach rate controlling factors, a more complete understanding of leaching processes is being developed. This, in turn, is leading to optimized accelerating conditions for a leach test

  12. Optimizing conditions for an accelerated leach test

    Pietrzak, R.F.; Fuhrmann, M.; Heiser, J.; Franz, E.M.; Colombo, P.

    1988-01-01

    An accelerated leach test for low-level radioactive waste forms is being developed to provide, in a short time, data that can be extrapolated to long time periods. The approach is to provide experimental conditions that will accelerate leaching without changing the dominant release mechanism. Experimental efforts have focused on combining individual factors that have been observed to accelerate leaching. These include elevated temperature, increased leachant volume, and reduced specimen size. The response of diffusion coefficients to various acceleration factors have been evaluated and provide information on experimental parameters that need to be optimized to increase leach rates. For example, these data show that large volumes of leachant are required when leaching portland cement waste forms at elevated temperatures because of high concentrations of dissolved species. Sr-85 leaching is particularly susceptible to suppression due to concentration effects while Cs-137 leaching is less so. Preliminary modeling using a diffusion mechanism (allowing for depletion) of a finite cylinder geometry indicates that during early portions of experiments (daily sampling intervals), leaching is diffusion controlled and more rapid than later in the same experiments (weekly or greater sampling intervals). For cement waste forms, this reduction in rate may be partially controlled by changes in physical structure and chemistry (sometimes related to environmental influences such as CO 2 ), but it is more likely associated with the duration of the sampling interval. 9 refs., 6 figs

  13. 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)

  14. Heap leaching for uranium

    1988-01-01

    Denison Mines Ltd. is using two bacterial leaching processes to combat the high cost of extracting uranium from low grade ore in thin reefs. Both processes use thiobacillus ferro-oxidans, a bacterium that employs the oxidation of ferrous iron and sulphur as its source of energy for growth. The first method is flood leaching, in which ore is subjected to successive flood, drain and rest cycles. The second, trickle leaching, uses sprinklers to douse the broken muck continuously with leaching solution. In areas where grades are too low to justify the expense of hauling the ore to the surface, the company is using this biological process underground to recover uranium. In 1987 Denison recovered 840 000 lb of uranium through bacterial heap leaching. It plans to have biological in-place leaching contribute 25% of the total uranium production by 1990. (fig.)

  15. 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

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

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

    2017-02-01

    Bio- and hydrometallurgical experimental setups at 2-l reactor scale for the processing of fly ash from municipal waste incinerators were explored. We aimed to compare chemical H 2 SO 4 leaching and bioleaching; the latter involved the use of H 2 SO 4 and a mixed culture of acidophilic bacteria. The leaching yields of several elements, including some of those considered as critical (Mg, Co, Ce, Cr, Ga, Nb, Nd, Sb and Sm), are provided. At the end of the experiments, both leaching methods resulted in comparable yields for Mg and Zn (>90%), Al and Mn (>85%), Cr (∼65%), Ga (∼60%), and Ce (∼50%). Chemical leaching showed the best yields for Cu (95%), Fe (91%), and Ni (93%), whereas bioleaching was effective for Nd (76%), Pb (59%), and Co (55%). The two leaching methods generated solids of different quality with respect to the original material as we removed and significantly reduced the metals amounts, and enriched solutions where metals can be recovered for example as mixed salts for further treatment. Compared to chemical leaching the bioleaching halved the use of H 2 SO 4 , i.e., a part of agent costs, as a likely consequence of bio-produced acid and improved metal solubility. Copyright © 2016 Elsevier Ltd. All rights reserved.

  17. Low leaching and low LWR photoresist development for 193 nm immersion lithography

    Ando, Nobuo; Lee, Youngjoon; Miyagawa, Takayuki; Edamatsu, Kunishige; Takemoto, Ichiki; Yamamoto, Satoshi; Tsuchida, Yoshinobu; Yamamoto, Keiko; Konishi, Shinji; Nakano, Katsushi; Tomoharu, Fujiwara

    2006-03-01

    With no apparent showstopper in sight, the adoption of ArF immersion technology into device mass production is not a matter of 'if' but a matter of 'when'. As the technology matures at an unprecedented speed, many of initial technical difficulties have been cleared away and the use of a protective layer known as top coat, initially regarded as a must, now becomes optional, for example. Our focus of interest has also sifted to more practical and production related issues such as defect reducing and performance enhancement. Two major types of immersion specific defects, bubbles and a large number of microbridges, were observed and reported elsewhere. The bubble defects seem to decrease by improvement of exposure tool. But the other type defect - probably from residual water spots - is still a problem. We suspect that the acid leaching from resist film causes microbridges. When small water spots were remained on resist surface after exposure, acid catalyst in resist film is leaching into the water spots even though at room temperature. After water from the spot is dried up, acid molecules are condensed at resist film surface. As a result, in the bulk of resist film, acid depletion region is generated underneath the water spot. Acid catalyzed deprotection reaction is not completed at this acid shortage region later in the PEB process resulting in microbridge type defect formation. Similar mechanism was suggested by Kanna et al, they suggested the water evaporation on PEB plate. This hypothesis led us to focus on reducing acid leaching to decrease residual water spot-related defect. This paper reports our leaching measurement results and low leaching photoresist materials satisfying the current leaching requirements outlined by tool makers without topcoat layer. On the other hand, Nakano et al reported that the higher receding contact angle reduced defectivity. The higher receding contact angle is also a key item to increase scan speed. The effort to increase the

  18. Does Tranexamic Acid Reduce Bleeding during Femoral Fracture Operation?

    Mohammad Haghighi

    2017-03-01

    Full Text Available Background:Proximal Femoral shaft fractures are commonly associated with marked blood loss which can lead topostoperative acute anemia and some other complications.Tranexamic acid (TA is an antifibrinolytic medication that reduces intra-and postoperative blood loss and transfusionrequirements during some elective surgeries (1-3.The aim of this study is to evaluate the effect of intravenous Tranexamic acid (TA on intraoperative blood loss and asubsequent need for transfusion in patients who were undergoing surgery for femoral shaft fractures in trauma setting.Methods:Thirty-eight ASA grade I-II patients undergoing proximal femoral shaft fracture surgery with intra medullarynailing were included in this double blind randomized controlled clinical trial. They were allocated into two groups. GroupI, the intervention group with eighteen patients received 15 mg/kg (TA via intravenous infusion before surgical incision.Patients in the placebo group received an identical volume of normal saline.Hemoglobin level was measured four hours before and after the surgeries. Postoperative blood loss and hemoglobinchange as well as transfusion rates and volumes were compared between the two groups.Results:Mean Percentage fall in hemoglobin after surgery were 1.75±0.84 and 2.04±1.9 in the study and placebo groups,respectively (P=0.570. Hemoglobin loss was higher in the placebo group. Transfusion rates was lower in TA group(5.6% compared to the placebo group (30% (P=0.06. No significant difference in The Allowable Blood Loss during thesurgery was found between the two groups (P=0.894.Conclusion:Preoperative treatment with TA reduces postoperative blood loss and the need for blood transfusion duringtraumatic femoral fracture operation.

  19. In-situ leach mining: the next quantum leap?

    Hancock, S.

    1988-01-01

    The opportunities and problems which in-situ leach mining technology presents to the mining industry are considered. These are exemplified by concerns addressed in the development of a proposal to mine uranium by in-situ leach techniques at Beverley in South Australia. The technique proposed at Beverley will use sulphuric acid with hydrogen peroxide or dissolved oxygen as the lixivient. Pre-treatment of the aquifer will be necessary to remove excess calcium carbonate, and the system will employ a slightly overpumped output of fluid through the wellfield to reduce the risk of excursions of mining solutions. The input and output patterns will also be varied to take account of the hydrogeological conditions such as confining bed thickness and permeability. Much study has been directed towards the post mining condition of the ore zone and the threat it may pose to the water resources of the region. 10 refs., 1 fig

  20. Unsaturated Fatty Acids Supplementation Reduces Blood Lead Level in Rats

    Skoczyńska, Anna; Wojakowska, Anna; Nowacki, Dorian; Bobak, Łukasz; Turczyn, Barbara; Smyk, Beata; Szuba, Andrzej; Trziszka, Tadeusz

    2015-01-01

    Some dietary factors could inhibit lead toxicity. The aim of this study was to evaluate the effect of dietary compounds rich in unsaturated fatty acids (FA) on blood lead level, lipid metabolism, and vascular reactivity in rats. Serum metallothionein and organs' lead level were evaluated with the aim of assessing the possible mechanism of unsaturated FA impact on blood lead level. For three months, male Wistar rats that were receiving drinking water with (100 ppm Pb) or without lead acetate were supplemented per os daily with virgin olive oil or linseed oil (0.2 mL/kg b.w.) or egg derived lecithin fraction: “super lecithin” (50 g/kg b.w.). Mesenteric artery was stimulated ex vivo by norepinephrine (NE) administered at six different doses. Lecithin supplementation slightly reduced pressor responses of artery to NE. Lead administered to rats attenuated the beneficial effect of unsaturated FA on lipid metabolism and vascular reactivity to adrenergic stimulation. On the other hand, the super lecithin and linseed oil that were characterized by low omega-6 to omega-3 ratio (about 1) reduced the blood lead concentration. This effect was observed in lead poisoned rats (p < 0.0001) and also in rats nonpoisoned with lead (p < 0.05). PMID:26075218

  1. 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.

  2. 21 CFR 146.148 - Reduced acid frozen concentrated orange juice.

    2010-04-01

    ... 21 Food and Drugs 2 2010-04-01 2010-04-01 false Reduced acid frozen concentrated orange juice. 146... Canned Fruit Juices and Beverages § 146.148 Reduced acid frozen concentrated orange juice. (a) Reduced acid frozen concentrated orange juice is the food that complies with the requirements for composition...

  3. Nitrate Leaching Management

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

  4. Nitrate leaching index

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

  5. Immobilized waste leaching

    Suarez, A.A.

    1989-01-01

    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) [pt

  6. Chlorination leaching of cadmium

    Lach, E.; Pajak, I.; Bojanowska, A.

    1978-01-01

    The results of the investigations on chlorination leaching of cadmium from dust coming from dry dust collector of sinter belt, that is leaching with water saturated with gaseous chlorine and leaching with solutions of ammonium chloride and sodium chloride were given. The optimum conditions for these processes were established. It was found, that the method of leaching in the presence of gaseous chlorine is more effective, as it allows to report into the solution over 90% cadmium contained in dust. Owing to technical difficulties, environmental protection and safety conditions more advantageous seems to be the use as leaching agent of the ammonium chloride solutions. When applying 20% NH 4 Cl and temperature of 60 0 C, the time of 2 hours and the ratio of solid to liquid of 1:5, 70% cadmium contained in the dust can be reported into the solution. (auth.)

  7. Does topical tranexamic acid reduce postcoronary artery bypass graft bleeding?

    Amir Mirmohammadsadeghi

    2018-01-01

    Full Text Available Background: Postoperative bleeding is a common problem in cardiac surgery. We tried to evaluate the effect of topical tranexamic acid (TA on reducing postoperative bleeding of patients undergoing on-pump coronary artery bypass graft (CABG surgery. Materials and Methods: One hundred and twenty-six isolated primary CABG patients were included in this clinical trial. They were divided blindly into two groups; Group 1, patients receiving 1 g TA diluted in 100 ml normal saline poured into mediastinal cavity before closing the chest and Group 2, patients receiving 100 ml normal saline at the end of operation. First 24 and 48 h chest tube drainage, hemoglobin decrease and packed RBC transfusion needs were compared. Results: Both groups were the same in baseline characteristics including gender, age, body mass index, ejection fraction, clamp time, bypass time, and operation length. During the first 24 h postoperatively, mean chest tube drainage in intervention group was 567 ml compared to 564 ml in control group (P = 0.89. Mean total chest tube drainage was 780 ml in intervention group and 715 ml in control group (P = 0.27. There was no significant difference in both mean hemoglobin decrease (P = 0.26 and packed RBC transfusion (P = 0.7. Topical application of 1 g TA diluted in 100 ml normal saline does not reduce postoperative bleeding of isolated on-pump CABG surgery. Conclusion: We do not recommend topical usage of 1 g TA diluted in 100 ml normal saline for decreasing blood loss in on-pump CABG patients.

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

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

    2016-03-01

    As the standard toxicity characteristic leaching procedure (TCLP) can not exhaust the acid neutralizing capacity of the cement rotary kiln co-processing solid wastes products which is particularly important for the assessment of the leaching concentrations of heavy metals. A modified TCLP was proposed. The extent of leaching of heavy metals is low using the TCLP and the leaching performance of the different metals can not be differentiated. Using the modified TCLP, however, Zn leaching was negligible during the first 180 h and then sharply increased (2.86 ± 0.18 to 3.54 ± 0.26 mg/L) as the acidity increased (pH leaching is enhanced using the modified TCLP. While Pb leached readily during the first 126 h and then leachate concentrations decreased to below the analytical detection limit. To conclude, this modified TCLP is a more suitable method for these cement rotary kiln co-processing products.

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

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

    2013-11-01

    A novel hydrometallurgical process was proposed for selective recovery of Cu, Ag, Au and Pd from waste printed circuit boards (PCBs). More than 99% of copper content was dissolved by using two consecutive sulfuric acid leaching steps in the presence of H2O2 as oxidizing agents. The solid residue of 2nd leaching step was treated by acidic thiourea in the presence of ferric iron as oxidizing agent and 85.76% Au and 71.36% Ag dissolution was achieved. The precipitation of Au and Ag from acidic thiourea leachate was investigated by using different amounts of sodium borohydride (SBH) as a reducing agent. The leaching of Pd and remained gold from the solid reside of 3rd leaching step was performed in NaClO-HCl-H2O2 leaching system and the effect of different parameters was investigated. The leaching of Pd and specially Au increased by increasing the NaClO concentration up to 10V% and any further increasing the NaClO concentration has a negligible effect. The leaching of Pd and Au increased by increasing the HCl concentration from 2.5 to 5M. The leaching of Pd and Au were endothermic and raising the temperature had a positive effect on leaching efficiency. The kinetics of Pd leaching was quite fast and after 30min complete leaching of Pd was achieved, while the leaching of Au need a longer contact time. The best conditions for leaching of Pd and Au in NaClO-HCl-H2O2 leaching system were determined to be 5M HCl, 1V% H2O2, 10V% NaClO at 336K for 3h with a solid/liquid ratio of 1/10. 100% of Pd and Au of what was in the chloride leachate were precipitated by using 2g/L SBH. Finally, a process flow sheet for the recovery of Cu, Ag, Au and Pd from PCB was proposed. Copyright © 2013 Elsevier Ltd. All rights reserved.

  10. Efficacy of Lactic Acid, Lactic Acid-Acetic Acid Blends, and Peracetic Acid To Reduce Salmonella on Chicken Parts under Simulated Commercial Processing Conditions.

    Ramirex-Hernandez, Alejandra; Brashears, Mindy M; Sanchez-Plata, Marcos X

    2018-01-01

    The poultry processing industry has been undergoing a series of changes as it modifies processing practices to comply with new performance standards for chicken parts and comminuted poultry products. The regulatory approach encourages the use of intervention strategies to prevent and control foodborne pathogens in poultry products and thus improve food safety and protect human health. The present studies were conducted to evaluate the efficacy of antimicrobial interventions for reducing Salmonella on inoculated chicken parts under simulated commercial processing conditions. Chicken pieces were inoculated by immersion in a five-strain Salmonella cocktail at 6 log CFU/mL and then treated with organic acids and oxidizing agents on a commercial rinsing conveyor belt. The efficacy of spraying with six different treatments (sterile water, lactic acid, acetic acid, buffered lactic acid, acetic acid in combination with lactic acid, and peracetic acid) at two concentrations was evaluated on skin-on and skin-off chicken thighs at three application temperatures. Skinless chicken breasts were used to evaluate the antimicrobial efficacy of lactic acid and peracetic acid. The color stability of treated and untreated chicken parts was assessed after the acid interventions. The lactic acid and buffered lactic acid treatments produced the greatest reductions in Salmonella counts. Significant differences between the control and water treatments were identified for 5.11% lactic acid and 5.85% buffered lactic acid in both skin-on and skin-off chicken thighs. No significant effect of treatment temperature for skin-on chicken thighs was found. Lactic acid and peracetic acid were effective agents for eluting Salmonella cells attached to chicken breasts.

  11. Practice of the counter-current trickle leaching of uranium ore by refreshed liquor of bacterial oxidation

    Chen Shian; Huang Xiangfu; Fan Baotuan

    1995-01-01

    The uranium ore of the Mine No. 753 is a high-silicate type primary one, in which the tetravalent uranium accounts for 85%, and the uranium grade is in the range of 0.36% to 0.442%. To reduce the engineering investment and the operating cost a four-stage counter-current trickle leaching pilot-plant test was carried out with the leaching time 50 days and acid consumption 38 kg per ton of ore, and the recovery of more than 95% was obtained. Using the counter-current trickle leaching mode and controlling the limit concentration of the harmful matters in the bacterial leaching liquor, the latter can be effectively oxidized by the synchronical regeneration. A trickle leaching comparative test of 25 ton ore single heap also gave a good result of more than 95% in extraction rate, and 30% acid consumption was saved and the 2.0% pyrolusite (containing MnO 2 40%) was eliminated. This process is feasible in technology and worth-while in economy for treating the uranium ore of Mine No. 753, and provides a new method of uranium ore trickle leaching

  12. Leaching of nuclear power reactor waste forms

    Endo, L.S.; Villalobos, J.P.; Miyamoto, H.

    1987-01-01

    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 cm 2 /s for boric acid waste form and 9 x 10 -9 cm 2 /s for ion-exchange resin waste. Strontium diffusivity coefficients found are about 3 x 10 -11 cm 2 /s and 9 x 10 -11 cm 2 /s respectively. (Author) [pt

  13. 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

    Delegard, C.H.; Rinehart, D.E.; Hoopes, F.V.

    1998-01-01

    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

  14. Uranium leaching by fungal metabolite

    Wang Yongdong; Li Guangyue; Ding Dexin; Hu Nan

    2012-01-01

    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)

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

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

    2015-01-01

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

  16. Rinsing with antacid suspension reduces hydrochloric acid-induced erosion.

    Alves, Maria do Socorro Coelho; Mantilla, Taís Fonseca; Bridi, Enrico Coser; Basting, Roberta Tarkany; França, Fabiana Mantovani Gomes; Amaral, Flávia Lucisano Botelho; Turssi, Cecilia Pedroso

    2016-01-01

    Mouthrinsing with antacids, following erosive episodes, have been suggested as a preventative strategy to minimize tooth surface loss due to their neutralizing effect. The purpose of this in situ study was to evaluate the effect of an antacid suspension containing sodium alginate, sodium bicarbonate and calcium carbonate in controlling simulated erosion of enamel of intrinsic origin. The experimental units were 48 slabs (3×3×2mm) of bovine enamel, randomly divided among 12 volunteers who wore palatal appliances with two enamel slabs. One of them was exposed extra-orally twice a day to 25mL of a hydrochloric acid (HCl) solution (0.01M, pH 2) for 2min. There were two independent phases, lasting 5 days each. In the first phase, according to a random scheme, half of the participants rinsed with 10mL of antacid suspension (Gaviscon(®), Reckitt Benckiser Healthcare Ltd.), while the remainder was rinsed with deionized water, for 1min. For the second phase, new slabs were inserted and participants switched to the treatment not received in the first stage. Therefore, the groups were as follows: (a) erosive challenge with HCl+antacid suspension; (b) erosive challenge with HCl+deionized water (DIW); (c) no erosive challenge+antacid suspension; (d) no erosive challenge+DIW. Specimens were assessed in terms of surface loss using optical profilometry and Knoop microhardness. The data were analyzed using repeated measures two-way analysis of variance and Tukey's tests. Compared to DIW rinses, surface loss of enamel was significantly lower when using an antacid rinse following erosive challenges (p=0.015). The Knoop microhardness of the enamel was significantly higher when the antacid rinse was used (p=0.026). The antacid suspension containing sodium alginate, sodium bicarbonate and calcium carbonate, rinsed after erosive challenges of intrinsic origin, reduced enamel surface loss. Copyright © 2015 Elsevier Ltd. All rights reserved.

  17. Leaching from waste incineration bottom ashes treated in a rotary kiln

    Hyks, Jiri; Nesterov, Igor; Mogensen, Erhardt

    2011-01-01

    Leaching from municipal solid waste incineration bottom ash treated in a rotary kiln was quantified using a combination of lab-scale leaching experiments and geochemical modelling. Thermal treatment in the rotary kiln had no significant effect on the leaching of Al, Ba, Ca, Mg, Si, Sr, Zn, sulfate...... the thermal treatment. Overall, rotary kiln thermal treatment of bottom ashes can be recommended to reduce the leaching of Cu, Pb, Cl and DOC; however, increased leaching of Cr and Mo should be expected....

  18. Photocatalytic properties of Co{sub 3}O{sub 4}/LiCoO{sub 2} recycled from spent lithium-ion batteries using citric acid as leaching agent

    Santana, I.L.; Moreira, T.F.M.; Lelis, M.F.F.; Freitas, M.B.J.G., E-mail: marcosbjg@gmail.com

    2017-04-01

    In this work, cobalt and lithium from the cathodes of spent lithium-ion batteries were recycled to synthesize a mixture of Co{sub 3}O{sub 4} and LiCoO{sub 2}. The positive electrode was leached with citric acid in the green recycling. After being heated to 85 °C, the leaching solution formed a pink sol, and after being dried at 120 °C for 24 h, it formed a gel, which is a precursor material for Co{sub 3}O{sub 4} and LiCoO{sub 2} synthesis. A mixture of Co{sub 3}O{sub 4} and LT-LiCoO{sub 2} was obtained after the calcination of the precursor material at 450 °C for 3 h. The photocatalytic properties of the Co{sub 3}O{sub 4} and LiCoO{sub 2} were tested in the discoloration of methylene blue dye. The discoloration efficiency of methylene blue dye in the presence of Co{sub 3}O{sub 4} and LiCoO{sub 2} was 90% after 10 h and 100% after 24 h of heterogeneous catalysis. The contribution of this work is that it presents a means to produce valuable materials with photocatalytic properties from recycled batteries through a spent Li-ion battery recycling process without polluting the environment. - Highlights: • Synthesis a mixture of Co{sub 3}O{sub 4}/LiCoO{sub 2} from spent Li-ion batteries. • Citric acid for leaching of the cathodes of the spent Li-ion batteries. • Co{sub 3}O{sub 4}/LiCoO{sub 2} as catalysts in the photodegradation of the methylene blue dye.

  19. Bicarbonate leaching of uranium

    Mason, C.

    1998-01-01

    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

  20. Bicarbonate leaching of uranium

    Mason, C.

    1998-12-31

    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.

  1. Comparison of oxidants in alkaline leaching of uranium ore

    Sreenivas, T.; Rajan, K.C.; Srinivas, K.; Anand Rao, K.; Manmadha Rao, M.; Venkatakrishnan, R.R.; Padmanabhan, N.P.H.

    2007-01-01

    The uranium minerals occurring in various ore deposits consists of predominantly uranous ion (U +4 ), necessitating use of an oxidant and other lixiviants for efficient dissolution during leaching. Unlike acid leaching route, where uranium minerals dissolution could be achieved efficiently with cheaper lixiviants, processing of ores by alkaline leaching route involve expensive lixiviants and drastic leaching conditions. Alkaline leaching of uranium ores becomes economical only upon using cheaper and efficient oxidants and conservation of other reagents by their recycle. The present paper gives efficacy of various oxidants - KMnO 4 , NaOCl, Cu - NH 3 , air and oxygen, in the leaching of uranium from a low-grade dolostone hosted uranium ore of India. A comparison based on technical merits and cost of the oxidant chemicals is discussed. (author)

  2. Chlorine-assisted leaching of Key Lake uranium ore

    Haque, K.E.

    1981-04-01

    Bench-scale chlorine-assisted leach tests were conducted on the Key Lake uranium ore. Leach tests conducted at 80 0 C on a slurry containing 50% solids during 10 hours of agitation gave the maximum extraction of uranium - 96% and radium-226 - 91%. Chlorine was added at 23.0 Kg Cl 2 /tonne of ore to maintain the leach slurry pH in the range of 1.5-1.0. To obtain residue almost free of radionuclides, hydrochloric acid leaches were conducted on the first stage leach residues. The second stage leach residue still was found to contain uranium - 0.0076% and radium-226 - 200 pCi/g of solids

  3. Comprehensive evaluation on effective leaching of critical metals from spent lithium-ion batteries.

    Gao, Wenfang; Liu, Chenming; Cao, Hongbin; Zheng, Xiaohong; Lin, Xiao; Wang, Haijuan; Zhang, Yi; Sun, Zhi

    2018-05-01

    Recovery of metals from spent lithium-ion batteries (LIBs) has attracted worldwide attention because of issues from both environmental impacts and resource supply. Leaching, for instance using an acidic solution, is a critical step for effective recovery of metals from spent LIBs. To achieve both high leaching efficiency and selectivity of the targeted metals, improved understanding on the interactive features of the materials and leaching solutions is highly required. However, such understanding is still limited at least caused by the variation on physiochemical properties of different leaching solutions. In this research, a comprehensive investigation and evaluation on the leaching process using acidic solutions to recycle spent LIBs is carried out. Through analyzing two important parameters, i.e. leaching speed and recovery rate of the corresponding metals, the effects of hydrogen ion concentration, acid species and concentration on these two parameters were evaluated. It was found that a leachant with organic acids may leach Co and Li from the cathode scrap and leave Al foil as metallic form with high leaching selectivity, while that with inorganic acids typically leach all metals into the solution. Inconsistency between the leaching selectivity and efficiency during spent LIBs recycling is frequently noticed. In order to achieve an optimal status with both high leaching selectivity and efficiency (especially at high solid-to-liquid ratios), it is important to manipulate the average leaching speed and recovery rate of metals to optimize the leaching conditions. Subsequently, it is found that the leaching speed is significantly dependent on the hydrogen ion concentration and the capability of releasing hydrogen ions of the acidic leachant during leaching. With this research, it is expected to improve understanding on controlling the physiochemical properties of a leaching solution and to potentially design processes for spent LIBs recycling with high industrial

  4. Hydrometallurgical recycling of lithium-ion batteries by reductive leaching with sodium metabisulphite.

    Vieceli, Nathália; Nogueira, Carlos A; Guimarães, Carlos; Pereira, Manuel F C; Durão, Fernando O; Margarido, Fernanda

    2018-01-01

    The hydrometallurgical extraction of metals from spent lithium-ion batteries (LIBs) was investigated. LIBs were first dismantled and a fraction rich in the active material was obtained by physical separation, containing 95% of the initial electrode, 2% of the initial steel and 22% of plastic materials. Several reducers were tested to improve metals dissolution in the leaching step using sulphuric acid. Sodium metabisulphite led to the best results and was studied in more detail. The best concentration of Na 2 S 2 O 5 was 0.1 M. The metals dissolution increased with acid concentration, however, concentrations higher than 1.25 M are unnecessary. Best results were reached using a stirring speed of 400 min -1 . The metals leaching efficiency from the active material (Li, Mn, Ni, Co) increased with the temperature and was above 80% for temperatures higher than 60 °C. The dissolution of metals also rose with the increase in the liquid/solid ratio (L/S), however, extractions above 85% can be reached at L/S as lower as 4.5 L/kg, which is favourable for further purification and recovery operations. About 90% of metals extraction can be achieved after only 0.5 h of leaching. Sodium metabisulphite can be an alternative reducer to increase the leaching of Li, Mn, Co, and Ni from spent LIBs. Copyright © 2017 Elsevier Ltd. All rights reserved.

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

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

    2006-07-01

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

  6. 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.

  7. Phosphorus recovery and leaching of trace elements from incinerated sewage sludge ash (ISSA).

    Fang, Le; Li, Jiang-Shan; Guo, Ming Zhi; Cheeseman, C R; Tsang, Daniel C W; Donatello, Shane; Poon, Chi Sun

    2018-02-01

    Chemical extraction of phosphorus (P) from incinerated sewage sludge ash (ISSA) is adversely influenced by co-dissolution of metals and metalloids. This study investigated P recovery and leaching of Zn, Cu, Pb, As and Ni from ISSA using inorganic acids (sulphuric acid and nitric acid), organic acids (oxalic acid and citric acid), and chelating agents (ethylenediaminetetraacetic acid (EDTA) and ethylene diamine tetramethylene phosphonate (EDTMP)). The aim of this study was to optimize a leaching process to recover P-leachate with high purity for P fertilizer production. The results show that both organic and inorganic acids extract P-containing phases but organic acids leach more trace elements, particularly Cu, Zn, Pb and As. Sulphuric acid was the most efficient for P recovery and achieved 94% of total extraction under the optimal conditions, which were 2-h reaction with 0.2 mol/L H 2 SO 4 at a liquid-to-solid ratio of 20:1. EDTA extracted only 20% of the available P, but the leachates were contaminated with high levels of trace elements under optimum conditions (3-h reaction with EDTA at 0.02 mol/L, pH 2, and liquid-to-solid ratio of 20:1). Therefore, EDTA was considered an appropriate pre-treatment agent for reducing the total metal/metalloid content in ISSA, which produced negligible changes in the structure of ISSA and reduced contamination during subsequent P extraction using sulphuric acid. Copyright © 2017 Elsevier Ltd. All rights reserved.

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

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

    2011-07-01

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

  9. An alginate-antacid formulation localizes to the acid pocket to reduce acid reflux in patients with gastroesophageal reflux disease.

    Rohof, Wout O; Bennink, Roel J; Smout, Andre J P M; Thomas, Edward; Boeckxstaens, Guy E

    2013-12-01

    Alginate rafts (polysaccharide polymers that precipitate into a low-density viscous gel when they contact gastric acid) have been reported to form at the acid pocket, an unbuffered pool of acid that floats on top of ingested food and causes postprandial acid reflux. We studied the location of an alginate formulation in relation to the acid pocket and the corresponding effects on reflux parameters and acid pocket positioning in patients with gastroesophageal reflux disease (GERD). We randomly assigned patients with symptomatic GERD and large hiatal hernias to groups who were given either (111)In-labeled alginate-antacid (n = 8, Gaviscon Double Action Liquid) or antacid (n = 8, Antagel) after a standard meal. The relative positions of labeled alginate and acid pocket were analyzed for 2 hours by using scintigraphy; reflux episodes were detected by using high-resolution manometry and pH-impedance monitoring. The alginate-antacid label localized to the acid pocket. The number of acid reflux episodes was significantly reduced in patients receiving alginate-antacid (3.5; range, 0-6.5; P = .03) compared with those receiving antacid (15; range, 5-20), whereas time to acid reflux was significantly increased in patients receiving alginate-antacid (63 minutes; range, 23-92) vs those receiving antacid (14 minutes; range, 9-23; P = .01). The acid pocket was located below the diaphragm in 71% of patients given alginate-antacid vs 21% of those given antacid (P = .08). There was an inverse correlation between a subdiaphragm position of the acid pocket and acid reflux (r = -0.76, P acid pocket and displaces it below the diaphragm to reduce postprandial acid reflux. These findings indicate the importance of the acid pocket in GERD pathogenesis and establish alginate-antacid as an appropriate therapy for postprandial acid reflux. Copyright © 2013 AGA Institute. Published by Elsevier Inc. All rights reserved.

  10. Extraction of seawater-derived neodymium from different phases of deep sea sediments by selective leaching

    Blaser, P.; Lippold, J. A.; Frank, N.; Gutjahr, M.; Böhm, E.

    2014-12-01

    In order to deduce reliable information about the interaction of the oceans with the climate system as a whole in the past, the reconstruction of water mass circulation is crucial. The analysis of seawater-derived neodymium isotopes (143Nd/144Nd, expressed as ɛNd) in marine sediments provides a unique proxy for deep water provenance in particular in the Atlantic [1]. The ɛNd signature and thus the mixing proportion of the local bottom water masses is archived in authigenic phases in the sediment. Obtaining seawater ɛNd from authigenic accretions bound to foraminiferal tests has lately become the preferred since most reliable method [2]. Attempts have also been made to extract the Nd-rich authigenic metal fraction by leaching it off the bulk sediment and thereby use this proxy with less effort, in the highest possible resolution and in sediments where foraminifera are not sufficiently present. However, often other sedimentary components are also leached in the process and contaminate the extracted Nd [3,4]. In this project several core-top and older sediments across the Atlantic have been leached in ten consecutive steps with either dilute buffered acetic acid or an acid-reductive solution. The leachates were analysed on their elemental and Nd isotope compositions, as well as rare earth element (REE) distributions. By graduating the total leaching procedure into smaller stages the results display which processes take place in the course of sediment leaching in the laboratory and which components of the sediment are most reactive. Thus, they help to better evaluate the quality of sediment leaches for ɛNd analysis. Clearly, organic calcite acts as a fast reacting buffer and at the point where its amount is sufficiently reduced the leaching of other components commences and the Nd concentration peaks. Corruption of the extracted ɛNd signal by non-authigenic sources in many cases occured early in the leaching sequence, indicating that only very cautious leaching

  11. Aqueous-chlorine leaching of typical Canadian uranium ores

    Haque, K.E.

    1982-01-01

    Laboratory-scale aqueous-chlorine leaches were conducted on quartz-pebble conglomerates, pegmatite and vein-type ores. Optimum leach temperatures, pulp density and retention times were determined. Uranium extraction of 98 per cent was obtained from the Elliot Lake, Madawaska Mines of Bancroft and Rabbit Lake ores, 96 per cent from the Key Lake ore and 86 per cent from the Agnew Lake ore. However, tailings containing 15-20 pCi g -1 of radium-226 were obtained only from the Elliot Lake and Agnew lake quartz-pebble conglomerates and Bancroft pegmatite-type ores by second-stage leaches with HCl. The second-stage leach results indicate that multistage (3 or 4) acid-chloride or salt-chloride leaches might be effective to obtain tailings containing 15-20 pCi 226 Ra g -1 from the high-grade vein-type ores. Comparative reagent-cost estimates show that the sulphuric-acid leach process is far less expensive than aqueous chlorine leaching. Nevertheless, only the aqueous chlorine and acid-chloride leaches in stages are effective in producing tailings containing 15-20 pCi 226 Ra g -1 from the typical Canadian uranium ores. (Auth.)

  12. n-3 fatty acids reduce plasma 20-hydroxyeicosatetraenoic acid and blood pressure in patients with chronic kidney disease.

    Barden, Anne E; Burke, Valerie; Mas, Emilie; Beilin, Lawrence J; Puddey, Ian B; Watts, Gerald F; Irish, Ashley B; Mori, Trevor A

    2015-09-01

    Metabolism of arachidonic acid by cytochrome P450 ω-hydroxylase leads to the formation of 20-hydroxyeicosatetraenoic acid (20-HETE) that regulates vascular function, sodium homeostasis and blood pressure (BP). Supplementation with n-3 fatty acids is known to alter arachidonic acid metabolism and reduce the formation of the lipid peroxidation products F2-isoprostanes, but the effect of n-3 fatty acids on 20-HETE has not been studied. We previously reported a significant effect of n-3 fatty acids but not coenzyme Q10 (CoQ) to reduce BP in a double-blind, placebo-controlled intervention, wherein patients with chronic kidney disease (CKD) were randomized to n-3 fatty acids (4 g), CoQ (200 mg), both supplements or control (4 g olive oil), daily for 8 weeks. This study examined the effect of n-3 fatty acids on plasma and urinary 20-HETE in the same study, as well as plasma and urinary F2-isoprostanes, and relate these to changes in BP. Seventy-four patients completed the 8-week intervention. n-3 fatty acids but not CoQ significantly reduced plasma 20-HETE (P = 0.001) and F2-isoprostanes (P fatty acids. This is the first report that n-3 fatty acid supplementation reduces plasma 20-HETE in humans and that this associates with reduced BP. These results provide a plausible mechanism for the reduction in BP observed in patients with CKD following n-3 fatty acid supplementation.

  13. Proton pump inhibitors reduce the size and acidity of the acid pocket in the stomach

    Rohof, Wout O.; Bennink, Roelof J.; Boeckxstaens, Guy E.

    2014-01-01

    The gastric acid pocket is believed to be the reservoir from which acid reflux events originate. Little is known about how changes in position, size, and acidity of the acid pocket contribute to the therapeutic effect of proton pump inhibitors (PPIs) in patients with gastroesophageal reflux disease

  14. Neural Network Modeling for the Extraction of Rare Earth Elements from Eudialyte Concentrate by Dry Digestion and Leaching

    Yiqian Ma; Srecko Stopic; Lars Gronen; Milovan Milivojevic; Srdjan Obradovic; Bernd Friedrich

    2018-01-01

    Eudialyte is a promising mineral for rare earth elements (REE) extraction due to its good solubility in acid, low radioactive, and relatively high content of REE. In this paper, a two stage hydrometallurgical treatment of eudialyte concentrate was studied: dry digestion with hydrochloric acid and leaching with water. The hydrochloric acid for dry digestion to eudialyte concentrate ratio, mass of water for leaching to mass of eudialyte concentrate ratio, leaching temperature and leaching time ...

  15. Glass leaching performance

    Chick, L.A.; Turcotte, R.P.

    1983-05-01

    Current understanding of the leaching performance of high-level nuclear waste (HLW) glass is summarized. The empirical model of waste glass leaching behavior developed shows that at high water flow rates the glass leach rate is kinetically limited to a maximum value. At intermediate water flow rates, leaching is limited by the solution concentration of silica and decreases with decreasing water flow rates. Release of soluble elements is controlled by silica dissolution because silica forms the binding network of the glass. At low water flow rates, mass loss rates reach values controlled by formation rates of alteration minerals, or by diffusion of dissolution products through essentially stagnant water. The parameters reviewed with respect to their quantifiable influence on leaching behavior include temperature, pH, leachant composition, glass composition, thermal history, and radiation. Of these, temperature is most important since the rate of mass loss approximately doubles with each 10 0 C increase in dilute solutions. The pH has small effects within the 4 to 10 range. The chemical composition of the leachant is most important with regard to its influence on alteration product formation. Glass composition exhibits the largest effects at high flow rates where improved glasses leach from ten to thirty times slower than glass 76 to 68. The effects of the thermal history (devitrification) of the glass are not likely to be significant. Radiation effects are important primarily in that radiolysis can potentially drive pH values to less than 4. Radiation damage to the glass causes insignificant changes in leaching performance

  16. 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.

  17. A Case of Gastric Antral Vascular Ectasia Which Was Aggravated by Acid Reducer

    Yukiomi Nakade

    2017-02-01

    Full Text Available Gastric antral vascular ectasia (GAVE is known to be characterized by red patches or spots in a diffuse or linear array in the antrum of the stomach. The precise etiology of GAVE remains to be elucidated. Argon plasma laser coagulation (APC has been used to control oozing from GAVE; however, there is no satisfactory long-term effect of APC in the control of oozing from GAVE. An acid reducer is used after APC because even physiological acid exposure might delay post-APC ulcer healing. We describe the case of a patient who had used an acid reducer and experienced repeated gastrointestinal hemorrhage due to GAVE. After ceasing to administer the acid reducer, incidences of hospitalization due to oozing from GAVE stopped. After the administration of the acid reducer was restarted, the patient had tarry stool, and diffuse oozing of blood was seen again. We report a first case of GAVE which was aggravated by acid reducer.

  18. 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.

  19. Mutualism between autotrophic and heterophic bacteria in leaching of low grade ores

    Khalid, Z.M.; Naeveke, R.

    1991-01-01

    During solubilization processes of low grade sulphidic ores, the auto trophic bacteria oxidize reduced sulphur compounds and ferrous iron to sulphates and ferric iron respectively. The ore leaching bio topes are not only colonized by auto trophic bacteria (Thiobacillus spp., Leptospirillum ferro oxidans and sulfolobus sp.) but the heterotrophic microorganisms, including bacteria and fungi of various species are also found in these habitats. The autotrophs, in addition to energy metabolism, also produce organic compounds which in excess amount inhibit their growth. Through the utilization of such compounds and also through the production of carbon dioxide and ammonia, these heterotorphs can help bio leaching processes. Effect of one of the heterotrophs; methylobacterium sp., a nitrogen scavenger, found in as association with the thio bacilli in one of the leaching bio tope in Germany was studied in leaching of a carbonate bearing complex (containing copper, iron, zinc and lead) sulphidic ore, in shake flask studies. T. ferro oxidans (Strain F-40) reported to be non nitrogen fixer and strain F-41, a nitrogen fixing thiobacillus were studied for leachability behaviour alone and in combination with T. thio oxidans (lacking nitrogen fixing ability) using media with and without added ammonium nitrogen. In addition the effect of methylobacterium sp. (alt-25) was also tested with the afore mentioned combinations. Nitrogen fixation by T. ferro oxidans did not suffice the nitrogen requirement and the leaching system in laboratory needed addition of nitrogen. The heterotrophic nitrogen scavenger also did not have a positive influence in nitrogen limited system. In case where ammonium nitrogen was also provided in the media, this heterotroph had a negative in own growth and leaving lesser amount available for thio bacilli. This high amount of acid is a limiting factor in bio leaching of high carbonate uranium ores. Uranium ore ecosystems have also been found to contain

  20. Chenodeoxycholic acid reduces intestinal permeability in newly weaned piglets

    Meer, van der Y.; Gerrits, W.J.J.; Bosch, van den M.; Holst, J.J.; Moreto, M.; Buurman, W.A.; Kulik, W.; Kempen, van T.A.T.G.

    2012-01-01

    Piglets are highly susceptible to gut health-related problems. Intravenously administered chenodeoxycholic acid (CDCA) affects gut health mediated through glucagon-like peptide 2 (GLP-2). To test whether CDCA is a suitable feed additive for improving gut health, a trial was performed with newly

  1. 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

  2. Study of hydrated Portland cement composition in regard to leaching resistance

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

    1997-01-01

    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

  3. Commercial test on uranium ore percolation leaching in Fuzhou uranium mine

    Cai Chunhui

    2002-01-01

    Commercial test on uranium ore percolation leaching was carried out according to ore characteristics of Fuzhou Uranium Mine and results from small test. Technological and economic indexes, such as leaching rate, acid consumption, leaching cycle, etc. are discussed. The general idea applying the test results to commercial production is presented, too

  4. A two-step leaching method designed based on chemical fraction distribution of the heavy metals for selective leaching of Cd, Zn, Cu, and Pb from metallurgical sludge.

    Wang, Fen; Yu, Junxia; Xiong, Wanli; Xu, Yuanlai; Chi, Ru-An

    2018-01-01

    For selective leaching and highly effective recovery of heavy metals from a metallurgical sludge, a two-step leaching method was designed based on the distribution analysis of the chemical fractions of the loaded heavy metal. Hydrochloric acid (HCl) was used as a leaching agent in the first step to leach the relatively labile heavy metals and then ethylenediamine tetraacetic acid (EDTA) was applied to leach the residual metals according to their different fractional distribution. Using the two-step leaching method, 82.89% of Cd, 55.73% of Zn, 10.85% of Cu, and 0.25% of Pb were leached in the first step by 0.7 M HCl at a contact time of 240 min, and the leaching efficiencies for Cd, Zn, Cu, and Pb were elevated up to 99.76, 91.41, 71.85, and 94.06%, by subsequent treatment with 0.2 M EDTA at 480 min, respectively. Furthermore, HCl leaching induced fractional redistribution, which might increase the mobility of the remaining metals and then facilitate the following metal removal by EDTA. The facilitation was further confirmed by the comparison to the one-step leaching method with single HCl or single EDTA, respectively. These results suggested that the designed two-step leaching method by HCl and EDTA could be used for selective leaching and effective recovery of heavy metals from the metallurgical sludge or heavy metal-contaminated solid media.

  5. Laboratory studies on leaching of low grade uranium ores and treatment of low level liquid waste generated by leaching experiments

    Palabrica, O.T.; Antonino, E.J.; Caluag, L.A.; Villamater, D.

    1980-07-01

    Acid leaching experiments of preconcentrated uranium ore were carried out at a pulp density of 50% solids, using sulfuric acid with sodium chlorate as oxidant. The different leaching parameters considered in this work were temperature, oxidant level and leaching time. In the experimental procedure, the concentration of oxidant and the temperature were varied to determine how they affect the leaching process. Experimental results are illustrated in tabulated form for better interpretation. Uranium analyses were done by fluorimetric and delayed-neutron activation analysis. An anion exchange method using Dowex 1 x 8, 200-400 mesh (Cl - ) was used in treating the low-level liquid waste generated by leaching experiments. The purpose of this treatment was to minimize radioactive contamination in the waste materials and also to recover some of the uranium left in the liquid waste. (author)

  6. Acid-reducing vagotomy is associated with reduced risk of subsequent ischemic heart disease in complicated peptic ulcer

    Wu, Shih-Chi; Fang, Chu-Wen; Chen, William Tzu-Liang; Muo, Chih-Hsin

    2016-01-01

    Abstract Persistent exacerbation of a peptic ulcer may lead to a complicated peptic ulcer (perforation or/and bleeding). The management of complicated peptic ulcers has shifted from acid-reducing vagotomy, drainage, and gastrectomy to simple local suture or non-operative (endoscopic/angiographic) hemostasis. We were interested in the long-term effects of this trend change. In this study, complicated peptic ulcer patients who received acid-reducing vagotomy were compared with those who received simple suture/hemostasis to determine the risk of ischemic heart disease (IHD). This retrospective cohort study analyzed 335,680 peptic ulcer patients recorded from 2000 to 2006 versus 335,680 age-, sex-, comorbidity-, and index-year matched comparisons. Patients with Helicobacter pylori (HP) infection were excluded. In order to identify the effect of vagus nerve severance, patients who received gastrectomy or antrectomy were also excluded. The incidence of IHD in both cohorts, and in the complicated peptic ulcer patients who received acid-reducing vagotomy versus those who received simple suture or hemostasis was evaluated. The overall incidence of IHD was higher in patients with peptic ulcer than those without peptic ulcer (17.00 vs 12.06 per 1000 person-years), with an adjusted hazard ratio (aHR) of 1.46 based on multivariable Cox proportional hazards regression analysis controlling for age, sex, Charlson's comorbidity index, and death (competing risk). While comparing peptic ulcer patients with acid-reducing vagotomy to those with simple suture/hemostasis or those without surgical treatment, the aHR (0.58) was the lowest in the acid-reducing vagotomy group. Patients with peptic ulcer have an elevated risk of IHD. However, complicated peptic ulcer patients who received acid-reducing vagotomy were associated with reduced risk of developing IHD. PMID:27977613

  7. URANIUM LEACHING AND RECOVERY PROCESS

    McClaine, L.A.

    1959-08-18

    A process is described for recovering uranium from carbonate leach solutions by precipitating uranium as a mixed oxidation state compound. Uranium is recovered by adding a quadrivalent uranium carbon;te solution to the carbonate solution, adjusting the pH to 13 or greater, and precipitating the uranium as a filterable mixed oxidation state compound. In the event vanadium occurs with the uranium, the vanadium is unaffected by the uranium precipitation step and remains in the carbonate solution. The uranium-free solution is electrolyzed in the cathode compartment of a mercury cathode diaphragm cell to reduce and precipitate the vanadium.

  8. Measurement of leached hulls

    Reilly, T.D.

    1979-07-01

    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 144 Ce-- 144 Pr. 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

  9. Tranexamic acid reduces blood loss during and after cesarean section: A double blinded, randomized, controlled trial

    Amr H. Yehia

    2014-03-01

    Conclusions: Tranexamic acid can be used safely to reduce blood loss during cesarean section. Reduced blood loss after tranexamic acid was associated with improvement of post-operative hemoglobin, hematocrit and with reduction of post-partum need for iron replacement.

  10. Effect of drying-wetting cycles on leaching behavior of cement solidified lead-contaminated soil.

    Li, Jiang-Shan; Xue, Qiang; Wang, Ping; Li, Zhen-Ze; Liu, Lei

    2014-12-01

    Lead contaminated soil was treated by different concentration of ordinary Portland cement (OPC). Solidified cylindrical samples were dried at 40°C in oven for 48 h subsequent to 24h of immersing in different solution for one drying-wetting. 10 cycles were conducted on specimens. The changes in mass loss of specimens, as well as leaching concentration and pH of filtered leachates were studied after each cycle. Results indicated that drying-wetting cycles could accelerate the leaching and deterioration of solidified specimens. The cumulative leached lead with acetic acid (pH=2.88) in this study was 109, 83 and 71 mg respectively for solidified specimens of cement-to-dry soil (C/Sd) ratios 0.2, 0.3 and 0.4, compared to 37, 30, and 25mg for a semi-dynamic leaching test. With the increase of cycle times, the cumulative mass loss of specimens increased linearly, but pH of filtered leachates decreased. The leachability and deterioration of solidified specimens increased with acidity of solution. Increases of C/Sd clearly reduced the leachability and deterioration behavior. Copyright © 2014 Elsevier Ltd. All rights reserved.

  11. Metal leaching in mine tailings: short-term impact of biochar and wood ash amendments.

    Beauchemin, Suzanne; Clemente, Joyce S; MacKinnon, Ted; Tisch, Bryan; Lastra, Rolando; Smith, Derek; Kwong, John

    2015-01-01

    Biochar is perceived as a promising amendment to reclaim degraded, metal-contaminated lands. The objective of this study was to compare the potential of biochar and wood ash amendments to reduce metal(loid) leaching in mine tailings. A 2-mo leaching experiment was conducted in duplicate on acidic and alkaline tailings, each mixed with 5 wt.% of one of the following amendments: three wood-derived, fast-pyrolysis biochars (OC > 57 wt.%) and two wood ash materials (organic carbon [OC] ≤ 16 wt.%); a control test with no carbon input was also added. The columns were leached with water after 1, 2, 4, 8, 16, 32, and 64 d, and the leachates were monitored for dissolved metals, OC, and pH. For the acidic and alkaline tailings, the most significant impact on metal mobility was observed with wood ash materials due to their greater neutralization potential (>15% CaCO eq.) compared with biochar (≤3.3% CaCO eq.). An increase of 1 pH unit in the wood ash-treated alkaline tailings led to an undesirable mobilization of As and Se. The addition of biochar did not significantly reduce the leaching of the main contaminants (Cu and Ni in the acidic tailings and As in the alkaline tailings) over 2 mo. The Se attenuation noted in some biochar-treated acid tailings may be mainly due to a slight alkaline effect rather than Se removal by biochar, given the low capacity for the fresh biochars to retain Se under acidic conditions (pH 4.5). The increased loss of dissolved OC in the biochar-amended systems was of short duration and was not associated with metal(loid) mobilization. Copyright © Her Majesty the Queen in Right of Canada, as represented by the Minister of Agriculture and Agri-Food Canada.

  12. Teichuronic acid reducing terminal N-acetylglucosamine residue linked by phosphodiester to peptidoglycan of Micrococcus luteus

    Gassner, G.T.; Dickie, J.P.; Hamerski, D.A.; Magnuson, J.K.; Anderson, J.S.

    1990-01-01

    Teichuronic acid-peptidoglycan complex isolated from Micrococcus luteus cells by lysozyme digestion in osmotically stabilized medium was treated with mild acid to cleave the linkage joining teichuronic acid to peptidoglycan. This labile linkage was shown to be the phosphodiester which joins N-acetylglucosamine, the residue located at the reducing end of the teichuronic acid, through its anomeric hydroxyl group to a 6-phosphomuramic acid, a residue of the glycan strand of peptidoglycan. 31 P nuclear magnetic resonance spectroscopy of the lysozyme digest of cell walls demonstrated the presence of a phosphodiester which was converted to a phosphomonoester by the conditions which released teichuronic acid from cell walls. Reduction of acid-liberated reducing end groups by NaB 3 H 4 followed by complete acid hydrolysis yielded [ 3 H] glucosaminitol from the true reducing end residue of teichuronic acid and [ 3 H]glucitol from the sites of fragmentation of teichuronic acid. The amount of N-acetylglucosamine detected was approximately stoichiometric with the amount of phosphate in the complex. Partial fragmentation of teichuronic acid provides an explanation of the previous erroneous identification of the reducing end residue

  13. Investigation of the leaching behavior of lead in stabilized/solidified waste using a two-year semi-dynamic leaching test.

    Xue, Qiang; Wang, Ping; Li, Jiang-Shan; Zhang, Ting-Ting; Wang, Shan-Yong

    2017-01-01

    Long-term leaching behavior of contaminant from stabilization/solidification (S/S) treated waste stays unclear. For the purpose of studying long-term leaching behavior and leaching mechanism of lead from cement stabilized soil under different pH environment, semi-dynamic leaching test was extended to two years to investigate leaching behaviors of S/S treated lead contaminated soil. Effectiveness of S/S treatment in different scenarios was evaluated by leachability index (LX) and effective diffusion coefficient (D e ). In addition, the long-term leaching mechanism was investigated at different leaching periods. Results showed that no significant difference was observed among the values of the cumulative release of Pb, D e and LX in weakly alkaline and weakly acidic environment (pH value varied from 5.00 to 10.00), and all the controlling leaching mechanisms of the samples immersed in weakly alkaline and weakly acidic environments turned out to be diffusion. Strong acid environment would significantly affect the leaching behavior and leaching mechanism of lead from S/S monolith. The two-year variation of D e appeared to be time dependent, and D e values increased after the 210 th day in weakly alkaline and weakly acidic environment. Copyright © 2016 Elsevier Ltd. All rights reserved.

  14. Uranium leaching from phosphatic sandstone and shale of Qatrani using citrate as a new leaching reagent

    Hussein, E.M.

    1997-01-01

    Uranium is found in Qatrani area (Southwest of Cairo and North of lake Qarun) in various forms in sedimentary rocks. Two important ore materials have been chosen for studying the recovery of their uranium contents namely; the phosphatic sandstone and the carbonaceous shale. The main emphasis in this thesis is the choice of an acid that would selectively leach uranium from thesis ores while leaving calcium phosphate and carbonate minerals minerals almost completely intact. Citric acid was indeed found advantageous due primarily to its strong ability to form stable complexes with uranium over a wide range of PH values beside the possibility of controlling thr solubility of calcium-bearing compounds by adding calcium citrate. The latter is actually characterized by its ability to exist in an unionized or associated from in citric acid solutions. From the general leaching characteristics of both uranium and P 2 O 5 from Qatrani phosphatic sandstone by citric acid, it was found that uranium could be completely leached beside the possibility of realizing a differential leaching percent values vs P 2 O 5 which is generally of limited solubility. Such a low solubility of P 2 O 5 has even been completely inhibited by providing calcium citrate to the citric acid solutions in amounts sufficient to exist in an optimum ionized non-associated state. Such a provision would render the solution unable to carry any further calcium ions thus the breakdown of the phosphate mineral was hindered while uranium has completely been selectively

  15. Accelerated leach test development program

    Fuhrmann, M.; Pietrzak, R.F.; Heiser, J.; Franz, E.M.; Colombo, P.

    1990-11-01

    In FY 1989, a draft accelerated leach test for solidified waste was written. Combined test conditions that accelerate leaching were validated through experimental and modeling efforts. A computer program was developed that calculates test results and models leaching mechanisms. This program allows the user to determine if diffusion controls leaching and, if this is the case, to make projections of releases. Leaching mechanisms other than diffusion (diffusion plus source term partitioning and solubility limited leaching) are included in the program is indicators of other processes that may control leaching. Leach test data are presented and modeling results are discussed for laboratory scale waste forms composed of portland cement containing sodium sulfate salt, portland cement containing incinerator ash, and vinyl ester-styrene containing sodium sulfate. 16 refs., 38 figs., 5 tabs

  16. 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.

  17. Urananite leaching: literature survey

    Grisham, G.F.; Bryant, E.A.; Williams, K.E.

    1979-04-01

    A literature survey was undertaken to provide background materials for a series of experiments involving the interaction of spent uranium dioxide fuel with various environments. Notes and references pertaining to the basic properties of UO/sub 2/ as produced and after reactor exposure are presented. The use of computerized literature searches is illustrated with specific topics related to leaching experiments. 57 references.

  18. Urananite leaching: literature survey

    Grisham, G.F.; Bryant, E.A.; Williams, K.E.

    1979-04-01

    A literature survey was undertaken to provide background materials for a series of experiments involving the interaction of spent uranium dioxide fuel with various environments. Notes and references pertaining to the basic properties of UO 2 as produced and after reactor exposure are presented. The use of computerized literature searches is illustrated with specific topics related to leaching experiments. 57 references

  19. Decontamination of acid mine water from Ronneburg/Thueringen which is high in sulfates and metals using sulfate-reducing bacteria. Final report of the preliminary phase

    Hard, B.; Friedrich, S.

    1995-01-01

    The mining in Eastern Europe, particularly in East-Germany, is a major source of pollution to the surrounding areas of the mines. With the end of the cold war the demand for uranium has drastically declined. Many of the pits have therefore been closed down or are in the process of closure such as the uranium mine in Ronneburg in Thueringen. One major problem is the safe-making of the pits and dumps as they are highly radioactive through naturally occurring uranium and other radioactive elements. Because of the leaching process through bacteria, drainage water is very acidic, with pH-values between 1-2. The water is very rich in magnesium, iron and aluminium sulfate. Here the application of a microbial process to decontaminate acid mine drainage was investigated. Decontamination of the water includes: - Increase in pH - decrease in sulfate concentrations - minimization of the metal and radionuclide load. Sulfate-reducing bacteria seem suitable for this process. In order for such a microbial process to be economically viable a cheap and widely available electron donar has to be used eg. methanol. The work carried out reports on the isolation, characterization and physiology of sulfate-reducing methylotrophic bacteria and their suitability for a decontamination process of sulfuric acid uranium mine water. (orig.) [de

  20. Mechanistic study of lead desorption during the leaching process of ion-absorbed rare earths: pH effect and the column experiment.

    Tang, Jie; Xue, Qiang; Chen, Honghan; Li, Wenting

    2017-05-01

    High concentrations of ammonium sulfate, often used in the in situ mining process, can result in a decrease of pH in the environment and dissolution of rare earth metals. Ammonium sulfate can also cause desorption of toxic heavy metals, leading to environmental and human health implications. In this study, the desorption behavior and fraction changes of lead in the ion-absorbed rare earth ore were studied using batch desorption experiments and column leaching tests. Results from batch desorption experiments showed that the desorption process of lead included fast and slow stages and followed an Elovich model well. The desorption rate and the proportion of lead content in the solution to the total lead in the soil were observed to increase with a decrease in the initial pH of the ammonium sulfate solution. The lead in soil included an acid-extractable fraction, reducible fraction, oxidizable fraction, and a residual fraction, with the predominant fractions being the reducible and acid-extractable fractions. Ninety-six percent of the extractable fraction in soil was desorbed into solution at pH = 3.0, and the content of the reducible fraction was observed to initially increase (when pH >4.0) and then decrease (when pH leaching tests indicated that the content of lead in the different fractions of soil followed the trend of reducible fraction > oxidizable fraction > acid-extractable fraction > residual fraction after the simulating leaching mining process. The change in pH was also found to have a larger influence on the acid-extractable and reducible fractions than the other two fractions. The proportion of the extractable fraction being leached was ca. 86%, and the reducible fraction was enriched along the migration direction of the leaching liquid. These results suggest that certain lead fractions may desorb again and contaminate the environment via acid rain, which provides significant information for environmental assessment and remediation after mining process

  1. In-situ uranium leaching

    Dotson, B.J.

    1986-01-01

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

  2. ALUMINUM AND CHROMIUM LEACHING WORKSHOP WHITEPAPER

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

    2007-01-01

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

  3. The experimental study of bacterial leaching at condition of different ore's diameter

    Liu Jinhui; Li Lin; Liu Yajie

    2006-01-01

    This papper compared the effect of leaching rate of uranium and the adaptability of bacteria with the condition of different ore's diameter (2-5 mm, 5-10 mm), which use the way of inleakage-leaching. The experiment use the way that firstly acid leaching, and then 2 bacterial leaching. As a reasult that the total leaching-rate of minute diameter ore are always high than the big diameter one. But for the quantum of consumed acid its just a opposition. During bacterial leaching the adaptability of bacteria in big diameter ore are high than in the minute one. So this experiment may offer a bases for a latter industry experiment which use big diameter ore's bacterial leaching. (authors)

  4. Leaching Mechanisms Program. Annual report

    Dougherty, D.; Colombo, P.; Doty, R.; Fuhrmann, M.

    1984-09-01

    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

  5. Study of Ascorbic Acid as Iron(III Reducing Agent for Spectrophotometric Iron Speciation

    Antesar Elmagirbi

    2012-10-01

    Full Text Available The study of ascorbic acid as a reducing agent for iron(III has been investigated in order to obtain an alternative carcinogenic reducing agent, hydroxylamine, used in spectrophotometric standard method based on the formation of a red-orange complex of Fe(II-o-phenanthroline. The study was optimised with regards to ascorbic acid concentration as well as pH solution. The results showed that ascorbic acid showed maximum capacity as reducing agent of iron(III under concentration of 4.46.10-4 M and pH solution of 1-4.Under these conditions, ascorbic acid reduced iron(III proportionally and performed similarly to that of hydroxylamine.  The method gave result to linear calibration over the range of 0.2-2 mg/L withhigh accuracy of 97 % and relative standard deviation of less than 2 %. This method was successfully applied to assay iron speciation in water samples.

  6. Leaching materials from cavities

    Hodgson, T.D.; Jordan, T.W.J.

    1980-01-01

    A material is leached from a cavity by contacting the material with a liquid and subjecting the liquid to a number of pressure cycles, each pressure cycle involving a decrease in pressure to cause boiling of the liquid, followed by a rise in pressure to inhibit the boiling. The method may include the step of heating the liquid to a temperature near to its boiling point. The material may be nuclear fuel pellets or calcium carbonate pellets. (author)

  7. Formamidine sulfinic acid as reducing agent in technetium-99m rhenium sulfide labelling

    Neves, M; Patricio, L [Laboratorio Nacional de Engenharia e Technologia Industrial, Sacavem (Portugal). Dept. de Radioisotopes; Ferronha, H [Laboratorio Nacional de Investigacao Veterinaria, Lisboa (Portugal)

    1989-08-01

    Labelling kinetic studies, radiochemical characterization and particle size evaluation of {sup 99m}Tc rhenium sulfide colloid using formamidine sulfinic acid as reducing agent are described. Comparison with the same colloid which makes use of Sn-sodium pyrophosphate complex as reducing agent showed higher labelling yields, simplification of labelling procedure and a longer shelf life when formamidine sulfinic acid was used. (author) 15 refs.; 7 figs.

  8. The leaching of base minerals from the calcines produced by the roasting of pyrite concentrates

    Nicol, M.J.; Filmer, A.O.

    1985-01-01

    A number of gold and uranium plants in South Africa concentrate the pyrite in the ore residue by flotation and roast the concentrate for the production of sulphuric acid. The calcine produced, which is predominantly hematite, is generally subjected to cyanidation for the recovery of gold and silver. The calcines often contain economically significant quantities of copper, nickel , cobalt and uranium. Prior treatment of the calcine for the recovery of these metals would be desirable in terms of the value of the products. Several processes for the leaching of the base metals from plant calcines have been investigated, and an important general conclusion is that an adequate recovery of the base metals requires that a large proportion of the iron should also be extracted. This observation led to a more extensive investigation of the kinetics of leaching of various iron oxides. The application of electrochemical theory and techniques resulted in a fuller understanding of the various factors that govern the rate of leaching of iron oxides. As a result of this fundamental work, alternative treatment schemes that should yield more efficient extraction from calcines were suggested. Several of these possibilities were investigated, and the most promising were found to require reducing conditions during the leach, or prior partial reduction of the calcine to magnetite or wustite

  9. New route for uranium concentrate production from Caetite ore, Bahia State, Brazil; dynamic leaching - direct precipitation

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

    2007-07-01

    The common uranium concentrate production consists of ore leaching, uranium purification/concentration by solvent extraction and uranium precipitation as ammonium diuranate steps. In the present work, a new route of uranium concentrate production from Caetite, BA-Brazil ore was investigated. The following steps were investigated: dynamic leaching of the ground ore with sulfuric acid; sulfuric liquor pre-neutralization until pH 3.7; uranium peroxide precipitation. The study was carried out in bath and continuous circuits. In the dynamic leaching of ground ore in agitated tanks the uranium content in the leached ore may be as low as 100 {mu}g/g U{sub 3}O{sub 8}, depending on grinding size. In the pre-neutralization step, the iron content in the liquor is decreased in 99 wt.%, dropping from 3.62 g/L to 0.030 g/L. The sulfate content in the liquor reduces from 46 g/L to 22 g/L. A calcinated final product assaying 99.7 wt.% U{sub 3}O{sub 8} was obtained. The full process recovery was over 94%. (author)

  10. Fish protein hydrolysate elevates plasma bile acids and reduces visceral adipose tissue mass in rats

    Liaset, Bjørn; Madsen, Lise; Hao, Qin

    2009-01-01

    levels relative to rats fed soy protein or casein. Concomitantly, the saithe FPH fed rats had reduced liver lipids and fasting plasma TAG levels. Furthermore, visceral adipose tissue mass was reduced and expression of genes involved in fatty acid oxidation and energy expenditure was induced in perirenal....../retroperitoneal adipose tissues of rats fed saithe FPH. Our results provide the first evidence that dietary protein sources with different amino acid compositions can modulate the level of plasma bile acids and our data suggest potential novel mechanisms by which dietary protein sources can affect energy metabolism....

  11. Selective leaching process for the recovery of copper and zinc oxide from copper-containing dust.

    Wu, Jun-Yi; Chang, Fang-Chih; Wang, H Paul; Tsai, Ming-Jer; Ko, Chun-Han; Chen, Chih-Cheng

    2015-01-01

    The purpose of this study was to develop a resource recovery procedure for recovering copper and zinc from dust produced by copper smelting furnaces during the manufacturing of copper-alloy wires. The concentrations of copper in copper-containing dust do not meet the regulation standards defined by the Taiwan Environmental Protection Administration; therefore, such waste is classified as hazardous. In this study, the percentages of zinc and copper in the dust samples were approximately 38.4% and 2.6%, respectively. To reduce environmental damage and recover metal resources for industrial reuse, acid leaching was used to recover metals from these inorganic wastes. In the first stage, 2 N of sulphuric acid was used to leach the dust, with pH values controlled at 2.0-3.0, and a solid-to-liquid ratio of 1:10. The results indicated that zinc extraction efficiency was higher than 95%. A selective acid leaching process was then used to recover the copper content of the residue after filtration. In the second stage, an additional 1 N of sulphuric acid was added to the suspension in the selective leaching process, and the pH value was controlled at 1.5-2.0. The reagent sodium hydroxide (2 N) was used as leachate at a pH greater than 7. A zinc hydroxide compound formed during the process and was recovered after drying. The yields for zinc and copper were 86.9-93.5% and 97.0-98.9%, respectively.

  12. The stability of iso-α-acids and reduced iso-α-acids in stored blood specimens.

    Rodda, Luke N; Gerostamoulos, Dimitri; Drummer, Olaf H

    2014-06-01

    The long-term stability of the iso-α-acids, and three structurally similar but chemically altered iso-α-acids (known as 'reduced iso-α-acids' and consisting of the rho-, tetrahydro- and hexahydro-iso-α-acid groups) were investigated in whole blood. Pools of blank blood spiked with the four beer-specific ingredient congener groups at two different concentration levels were stored at 20°C, 4°C and -20°C; and extracted in duplicate in weeks 1, 3, 5 and 8, using a previously published method. A loss of 15% of the initial concentration was considered to indicate possible instability and losses greater than 30% demonstrated significant losses. The individual analytes within the four iso-α-acid groups were also measured to determine which iso-α-acids were subject to greater degradation and were responsible for the overall group instability. All four iso-α-acid groups showed significant losses after 8 weeks of storage under room temperature conditions in particularly the natural iso-α-acid group where major losses were observed (96% and 85% losses for low and high concentrations, respectively). Some degradation in all iso-α-acid groups were seen at 4°C samples predominantly due to the 'n' analogs of the groups showing an increased instability in blood. The -20°C storage conditions resulted in minimal changes in concentrations of all analytes. Higher than frozen storage temperatures can result in substantial changes on the stability of the iso-α-acid type groups in blood. The aim of this study was to highlight the stabilities of the IAA analytes in order to assist in the interpretation of IAA in stored blood specimens. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

  13. Leaching studies of low-level radioactive waste forms

    Dayal, R.; Arora, H.; Milian, L.; Clinton, J.

    1985-01-01

    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

  14. A procedure for reducing the concentration of hydrogen ions in acid anionic eluate and equipment therefore

    Parobek, P.; Baloun, S.; Plevac, S.

    1989-01-01

    The method is described of reducing the concentration of hydrogen ions in acid anionic eluate produced in the separation of uranium or other metals, in which anion exchanger elution, precipitation, filtration and precipitate and anion exchanger washing are used. The technological line for such elution comprises at least one ion exchange column and at least one container. They together form the first and the second stages of preparation of the acid anion elution solution, the sorption-elution separation of hydrogen ions on an cation exchanger being inserted between them. The preparation of the solution is divide into two stages. In the first stage, the acid and part of the solution for the preparation of the acid anion elution solution are supplied. The resulting enriched acid elution solution is fe onto the cation exchanger where the hydrogen ion concentration i reduced. It is then carried into the second stage where it is mixed with the remaining part of the solution. (B.S.)

  15. The Arabidopsis thaliana REDUCED EPIDERMAL FLUORESCENCE1 gene encodes an aldehyde dehydrogenase involved in ferulic acid and sinapic acid biosynthesis.

    Nair, Ramesh B; Bastress, Kristen L; Ruegger, Max O; Denault, Jeff W; Chapple, Clint

    2004-02-01

    Recent research has significantly advanced our understanding of the phenylpropanoid pathway but has left in doubt the pathway by which sinapic acid is synthesized in plants. The reduced epidermal fluorescence1 (ref1) mutant of Arabidopsis thaliana accumulates only 10 to 30% of the sinapate esters found in wild-type plants. Positional cloning of the REF1 gene revealed that it encodes an aldehyde dehydrogenase, a member of a large class of NADP(+)-dependent enzymes that catalyze the oxidation of aldehydes to their corresponding carboxylic acids. Consistent with this finding, extracts of ref1 leaves exhibit low sinapaldehyde dehydrogenase activity. These data indicate that REF1 encodes a sinapaldehyde dehydrogenase required for sinapic acid and sinapate ester biosynthesis. When expressed in Escherichia coli, REF1 was found to exhibit both sinapaldehyde and coniferaldehyde dehydrogenase activity, and further phenotypic analysis of ref1 mutant plants showed that they contain less cell wall-esterified ferulic acid. These findings suggest that both ferulic acid and sinapic acid are derived, at least in part, through oxidation of coniferaldehyde and sinapaldehyde. This route is directly opposite to the traditional representation of phenylpropanoid metabolism in which hydroxycinnamic acids are instead precursors of their corresponding aldehydes.

  16. Can Tranexamic Acid Reduce Blood Loss during Major Cardiac Surgery? A Pilot Study.

    Compton, Frances; Wahed, Amer; Gregoric, Igor; Kar, Biswajit; Dasgupta, Amitava; Tint, Hlaing

    2017-09-01

    We examined the effectiveness of tranexamic acid in preventing intraoperative blood loss during major cardiac surgery. Out of initial 81 patients undergoing major cardiac surgery (both coronary artery bypass and valve repair procedures) at our teaching hospital, sixty-seven patients were selected for this study. We compared estimated blood loss, decrease in percent hemoglobin and hematocrit following surgery between two groups of patients (none of them received any blood product during surgery), one group receiving no tranexamic acid (n=17) and another group receiving tranexamic acid (n=25). In the second study, we combined these patients with patients receiving modest amounts of blood products (1-2 unit) and compared these parameters between two groups of patients (25 patients received no tranexamic acid, 42 patients received tranexamic acid). In patients who received no blood product during surgery, those who received no tranexamic acid showed statistically significant (independent t-test two tailed at p tranexamic acid (mean: 987.2 mL, SD: 459.9, n=25). We observed similar results when the patients receiving no blood products and patients receiving modest amount of blood products were combined based on the use of tranexamic acid or not. No statistically significant difference was observed in percent reduced hemoglobin or hematocrit following surgery in any group of patients. We conclude that intraoperative antifibrinolytic therapy with tranexamic acid does not reduce intraoperative blood loss during major cardiac surgery which contradicts popular belief. © 2017 by the Association of Clinical Scientists, Inc.

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

    El-Kamash, A.M.

    2013-01-01

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

  18. Extraction of nickel from Ramu laterite by sulphation roasting-water leaching

    Wang, Weiwei; Du, Shangchao; Liu, Guo; Tang, Jianwen; Lu, Yeda; Lv, Dong

    2017-08-01

    Recovery of nickel from a PNG nickel laterite with high content of iron by a sulphation roasting-water leaching has been studied. The influences of sulfuric acid/ore ratio, temperature of roasting and water on recovery efficiency were investigated. The effective separation of nickel over the co-existed elements including iron was achieved by the process with mixing, curing, roasting and leaching stages. Near 100% of nickel was leached from the roasted laterite by water at 80°C in an atmospheric air, while co-leaching of about 2% of iron, under the optimal pre-treatment conditions with the ratio of acid: ore around 0.45:1 and the roasting temperature about 650°C. The advantages and disadvantages of sulphation atmospheric leaching are compared with pressure acid leaching with engineering consideration.

  19. A novel akermanite/poly (lactic-co-glycolic acid) porous composite scaffold fabricated via a solvent casting-particulate leaching method improved by solvent self-proliferating process.

    Deng, Yao; Zhang, Mengjiao; Chen, Xianchun; Pu, Ximing; Liao, Xiaoming; Huang, Zhongbing; Yin, Guangfu

    2017-08-01

    Desirable scaffolds for tissue engineering should be biodegradable carriers to supply suitable microenvironments mimicked the extracellular matrices for desired cellular interactions and to provide supports for the formation of new tissues. In this work, a kind of slightly soluble bioactive ceramic akermanite (AKT) powders were aboratively selected and introduced in the PLGA matrix, a novel l-lactide modified AKT/poly (lactic- co -glycolic acid) (m-AKT/PLGA) composite scaffold was fabricated via a solvent casting-particulate leaching method improved by solvent self-proliferating process. The effects of m-AKT contents on properties of composite scaffolds and on MC3T3-E1 cellular behaviors in vitro have been primarily investigated. The fabricated scaffolds exhibited three-dimensional porous networks, in which homogenously distributed cavities in size of 300-400 μm were interconnected by some smaller holes in a size of 100-200 μm. Meanwhile, the mechanical structure of scaffolds was reinforced by the introduction of m-AKT. Moreover, alkaline ionic products released by m-AKT could neutralize the acidic degradation products of PLGA, and the apatite-mineralization ability of scaffolds could be largely improved. More valuably, significant promotions on adhesion, proliferation, and differentiation of MC3T3-E1 have been observed, which implied the calcium, magnesium and especially silidous ions released sustainably from composite scaffolds could regulate the behaviors of osteogenesis-related cells.

  20. Leaching of natural colloids from forest topsoils and their relevance for phosphorus mobility.

    Missong, Anna; Holzmann, Stefan; Bol, Roland; Nischwitz, Volker; Puhlmann, Heike; V Wilpert, Klaus; Siemens, Jan; Klumpp, Erwin

    2018-09-01

    The leaching of P from the upper 20cm of forest topsoils influences nutrient (re-)cycling and the redistribution of available phosphate and organic P forms. However, the effective leaching of colloids and associated P forms from forest topsoils was so far sparsely investigated. We demonstrated through irrigation experiments with undisturbed mesocosm soil columns, that significant proportions of P leached from acidic forest topsoils were associated with natural colloids. These colloids had a maximum size of 400nm. By means of Field-flow fractionation the leached soil colloids could be separated into three size fractions. The size and composition was comparable to colloids present in acidic forest streams known from literature. The composition of leached colloids of the three size classes was dominated by organic carbon. Furthermore, these colloids contained large concentrations of P which amounted between 12 and 91% of the totally leached P depending on the type of the forest soil. The fraction of other elements leached with colloids ranged between 1% and 25% (Fe: 1-25%; C org : 3-17%; Al: leaching. Leaching of total and colloid-associated P from the forest surface soil did not increase with increasing bulk soil P concentrations and were also not related to tree species. The present study highlighted that colloid-facilitated P leaching can be of higher relevance for the P leaching from forest surface soils than dissolved P and should not be neglected in soil water flux studies. Copyright © 2018 Elsevier B.V. All rights reserved.

  1. Effect of Thiamine, Ascorbic acid and Gibberellic acid (GA3 on Growth Characteristics, Pigment Content and Reduced Sugars of Petunia

    moslem salehi

    2017-02-01

    Full Text Available Introduction: Bedding plants, especially petunia is important element for urban landscaping and attracted the attention of landscapers. This is due to some properties such as growth habit and color. The petunia (Petunia hybrida L. belongs to Solanaceae family that has annual and perennial varieties. This plant is originally from Argentina, Brazil and Uruguay. Some plant growth regulators such as gibberellic acid (GA3 and vitamins including thiamine and ascorbic acid affect plant growth and development and may extend flowering period. Vitamin C affects cell division and cell growth in plants and is effective on the feeding cycle activity in higher plants and it has an important role in electron transport system. The concentrations of 50 and 100 ppm of vitamin C and thiamine can increase the plant height, leaf number, leaf area, fresh and dry weight, and chemical compounds of the Syngonium plant. The application of 100 mg/l of GA3 significantly increased plant height and the number of leaves of gladiolus. Material and methods: The experiment was arranged in a factorial based on a completely randomized design with five replications. In this research, growth characteristics (lateral branch number, flower number, flower diameter, stem diameter, root length, and lateral branch length and biochemical characteristics (chlorophyll a, chlorophyll b, total chlorophyll, carotenoids, and reducing sugar were measured. After seeding and transplanting the seedling at 6 leaf stage, plants sprayed at 4 various growth stages with following treatments: 1-\tControl 2-\tVitamin C(100 mg/l 3-\tThiamin (100 mg/l 4-\tGibberellic acid (100 mg/l 5-\tVitamin C and Thiamin (The concentration of both 100 mg/l 6-\tVitamin C and Gibberellic acid (The concentration of both 100 mg/l 7-\tThiamin and Gibberellic acid (The concentration of both 100 mg/l 8-\tVitamin C, Thiamin and Gibberellic acid (The concentration of three 100 mg/l Data obtained from the measured parameters

  2. Leaching From Biomass Gasification Residues

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

    2011-01-01

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

  3. Acid and enzymatic hydrolysis to recover reducing sugars from cassava bagasse: an economic study

    Woiciechowski Adenise Lorenci

    2002-01-01

    Full Text Available The objective of this work was to study the acid and enzymatic hydrolysis of cassava bagasse for the recovery of reducing sugars and to establish the operational costs. A statistical program "Statistica", based on the surface response was used to optimize the recovery of reducing sugars in both the processes. The process economics was determined considering the values of reducing sugars obtained at laboratory scale, and the operations costs of a cylindrical reactor of 1500 L, with flat walls at the top and bottom. The reactor was operated with 150 kg of cassava bagasse and 1350 kg of water. The yield of the acid hydrolysis was 62.4 g of reducing sugars from 100 g of cassava bagasse containing 66% starch. It represented 94.5% of reducing sugar recovery. The yield of the enzymatic hydrolysis was 77.1 g of reducing sugars from 120 g of cassava bagasse, which represented 97.3% of reducing sugars recovery. Concerning to the time, a batch of acid hydrolysis required 10 minutes, plus the time to heat and cool the reactor, and a batch of the enzymatic hydrolysis needed 25 hours and 20 minutes, plus the time to heat and to cool the reactor. Thus, the acid hydrolysis of 150 kg of cassava bagasse required US$ 34.27, and the enzymatic hydrolysis of the same amount of cassava bagasse required US$ 2470.99.

  4. Metal leaching from refinery waste hydroprocessing catalyst.

    Marafi, Meena; Rana, Mohan S

    2018-05-18

    The present study aims to develop an eco-friendly methodology for the recovery of nickel (Ni), molybdenum (Mo), and vanadium (V) from the refinery waste spent hydroprocessing catalyst. The proposed process has two stages: the first stage is to separate alumina, while the second stage involves the separation of metal compounds. The effectiveness of leaching agents, such as NH 4 OH, (NH 4 ) 2 CO 3 , and (NH 4 ) 2 S 2 O 8 , for the extraction of Mo, V, Ni, and Al from the refinery spent catalyst has been reported as a function of reagent concentration (0.5 to 2.0 molar), leaching time (1 to 6 h), and temperature (35 to 60°C). The optimal leaching conditions were achieved to obtain the maximum recovery of Mo, Ni, and V metals. The effect of the mixture of multi-ammonium salts on the metal extraction was also studied, which showed an adverse effect for Ni and V, while marginal improvement was observed for Mo leaching. The ammonium salts can form soluble metal complexes, in which stability or solubility depends on the nature of ammonium salt and the reaction conditions. The extracted metals and support can be reused to synthesize a fresh hydroprocessing catalyst. The process will reduce the refinery waste and recover the expensive metals. Therefore, the process is not only important from an environmental point of view but also vital from an economic perspective.

  5. Heap Leaching Technology. Moving the Frontier for Treatment: Applications in Niger and Namibia

    Thiry, Jacques; Bustos, Sergio

    2014-01-01

    • Uranium is being successfully extracted from low grade ores by heap leaching operations; • The response of the reaction system both at acid or alkaline leaching conditions is well know; • Proper characterization of ore feed is required to anticipate agglomeration quality, heap permeability and stability, and uranium dissolution kinetics and final recovery; • Many laboratory, bench scale tests and pilot plant demonstration at proper scale are necessary to provide suitable design parameters and to fit modeling efforts to actual results; • Large space for optimization opportunities to reduce ore throughput, water and reagents consumption; • Proper effluent solution management and control as well as proper residue disposal are required for safe and clean operation

  6. 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...

  7. Chemical treatment of coal by grinding and aqueous caustic leaching

    Balaz, P.; LaCount, R.B.; Kern, D.G.; Turcaniova, L. [Slovak Academy of Sciences, Kosice (Slovakia). Inst. of Geotechnics

    2001-04-01

    The aim of this work has been to point out the possibility of using GACL process for chemical cleaning of brown coal Nivaky (Slovakia) and Pittsburgh coal. Simultaneous grinding and aqueous chemical leaching, which is the principle of the process, reduces the inorganic and inorganic sulfur content in both coals. Dearsenificiation nearly up to 96% is detected in GACL-treated samples of Novaky coal. The possibility of enhancing the recovery of humic acid as a consequence of GACL treatment is demonstrated. The process under study works under atmospheric pressure, temperature of 90{degree}C and NaOH consumption, which is six times lower compared with the MCL process. Further research is needed to minimize the wear of grinding media and to improve the washing step. 24 refs., 7 figs., 3 tabs.

  8. Ascorbic acid reduces noise-induced nitric oxide production in the guinea pig ear.

    Heinrich, Ulf-Rüdiger; Fischer, Ilka; Brieger, Jürgen; Rümelin, Andreas; Schmidtmann, Irene; Li, Huige; Mann, Wolf J; Helling, Kai

    2008-05-01

    Noise-induced hearing loss can be caused, among other causes, by increased nitric oxide (NO) production in the inner ear leading to nitroactive stress and cell destruction. Some studies in the literature suggest that the degree of hearing loss (HL) could be reduced in an animal model through ascorbic acid supplementation. To identify the effect of ascorbic acid on tissue-dependent NO content in the inner ear of the guinea pig, we determined the local NO production in the organ of Corti and the lateral wall separately 6 hours after noise exposure. Prospective animal study in guinea pigs. Over a period of 7 days, male guinea pigs were supplied with minimum (25 mg/kg body weight/day) and maximum (525 mg/kg body weight/day) ascorbic acid doses, and afterwards exposed to noise (90 dB sound pressure level for 1 hour). The acoustic-evoked potentials were recorded before and after noise exposure. The organ of Corti and the lateral wall were incubated differently for 6 hours in culture medium, and the degree of NO production was determined by chemiluminescence. Ascorbic acid treatment reduced the hearing threshold shift after noise exposure depending on concentration. When the maximum ascorbic acid dose was substituted, NO production was significantly reduced in the lateral wall after noise exposure and slightly reduced in the organ of Corti. Oral supplementation of the natural radical scavenger ascorbic acid reduces the NO-production rate in the inner ear in noisy conditions. This finding supports the concept of inner ear protection by ascorbic acid supplementation.

  9. N-3 fatty acids reduced trans fatty acids retention and increased docosahexaenoic acid levels in the brain.

    Lavandera, Jimena Verónica; Saín, Juliana; Fariña, Ana Clara; Bernal, Claudio Adrián; González, Marcela Aída

    2017-09-01

    The levels of docosahexaenoic acid (DHA, 22:6n-3) and arachidonic acid (AA, 20:4n-6) are critical for the normal structure and function of the brain. Trans fatty acids (TFA) and the source of the dietary fatty acids (FA) interfere with long-chain polyunsaturated fatty acids (LC-PUFA) biosynthesis. The aim of this study was to investigate the effect of TFA supplementation in diets containing different proportions of n-9, n-6, and n-3 FA on the brain FA profile, including the retention of TFA, LC-PUFA levels, and n-6/n-3 PUFA ratios. These parameters were also investigated in the liver, considering that LC-PUFA are mainly bioconverted from their dietary precursors in this tissue and transported by serum to the brain. Also, stearoyl-CoA desaturase-1 (SCD1) and sterol regulatory element-binding protein-1c (SREBP-1c) gene expressions were evaluated. Male CF1 mice were fed (16 weeks) diets containing different oils (olive, corn, and rapeseed) with distinct proportions of n-9, n-6, and n-3 FA (55.2/17.2/0.7, 32.0/51.3/0.9, and 61.1/18.4/8.6), respectively, substituted or not with 0.75% of TFA. FA composition of the brain, liver, and serum was assessed by gas chromatography. TFA were incorporated into, and therefore retained in the brain, liver, and serum. However, the magnitude of retention was dependent on the tissue and type of isomer. In the brain, total TFA retention was lower than 1% in all diets. Dietary n-3 PUFA decreased TFA retention and increased DHA accretion in the brain. The results underscore the importance of the type of dietary FA on the retention of TFA in the brain and also on the changes of the FA profile.

  10. Tranexamic Acid Reduced the Percent of Total Blood Volume Lost During Adolescent Idiopathic Scoliosis Surgery.

    Jones, Kristen E; Butler, Elissa K; Barrack, Tara; Ledonio, Charles T; Forte, Mary L; Cohn, Claudia S; Polly, David W

    2017-01-01

    Multilevel posterior spine fusion is associated with significant intraoperative blood loss. Tranexamic acid is an antifibrinolytic agent that reduces intraoperative blood loss. The goal of this study was to compare the percent of total blood volume lost during posterior spinal fusion (PSF) with or without tranexamic acid in patients with adolescent idiopathic scoliosis (AIS). Thirty-six AIS patients underwent PSF in 2011-2014; the last half (n=18) received intraoperative tranexamic acid. We retrieved relevant demographic, hematologic, intraoperative and outcomes information from medical records. The primary outcome was the percent of total blood volume lost, calculated from estimates of intraoperative blood loss (numerator) and estimated total blood volume per patient (denominator, via Nadler's equations). Unadjusted outcomes were compared using standard statistical tests. Tranexamic acid and no-tranexamic acid groups were similar (all p>0.05) in mean age (16.1 vs. 15.2 years), sex (89% vs. 83% female), body mass index (22.2 vs. 20.2 kg/m2), preoperative hemoglobin (13.9 vs. 13.9 g/dl), mean spinal levels fused (10.5 vs. 9.6), osteotomies (1.6 vs. 0.9) and operative duration (6.1 hours, both). The percent of total blood volume lost (TBVL) was significantly lower in the tranexamic acid-treated vs. no-tranexamic acid group (median 8.23% vs. 14.30%, p = 0.032); percent TBVL per level fused was significantly lower with tranexamic acid than without it (1.1% vs. 1.8%, p=0.048). Estimated blood loss (milliliters) was similar across groups. Tranexamic acid significantly reduced the percentage of total blood volume lost versus no tranexamic acid in AIS patients who underwent PSF using a standardized blood loss measure.Level of Evidence: 3. Institutional Review Board status: This medical record chart review (minimal risk) study was approved by the University of Minnesota Institutional Review Board.

  11. Sulfur dioxide leaching of spent zinc-carbon-battery scrap

    Avraamides, J.; Senanayake, G.; Clegg, R. [A.J. Parker Cooperative Research Centre for Hydrometallurgy, Murdoch University, Perth, WA 6150 (Australia)

    2006-09-22

    Zinc-carbon batteries, which contain around 20% zinc, 35% manganese oxides and 10% steel, are currently disposed after use as land fill or reprocessed to recover metals or oxides. Crushed material is subjected to magnetic separation followed by hydrometallurgical treatment of the non-magnetic material to recover zinc metal and manganese oxides. The leaching with 2M sulfuric acid in the presence of hydrogen peroxide recovers 93% Zn and 82% Mn at 25{sup o}C. Alkaline leaching with 6M NaOH recovers 80% zinc. The present study shows that over 90% zinc and manganese can be leached in 20-30min at 30{sup o}C using 0.1-1.0M sulfuric acid in the presence of sulfur dioxide. The iron extraction is sensitive to both acid concentration and sulfur dioxide flow rate. The effect of reagent concentration and particle size on the extraction of zinc, manganese and iron are reported. It is shown that the iron and manganese leaching follow a shrinking core kinetic model due to the formation of insoluble metal salts/oxides on the solid surface. This is supported by (i) the decrease in iron and manganese extraction from synthetic Fe(III)-Mn(IV)-Zn(II) oxide mixtures with increase in acid concentration from 1M to 2M, and (ii) the low iron dissolution and re-precipitation of dissolved manganese and zinc during prolonged leaching of battery scrap with low sulfur dioxide. (author)

  12. The Polyunsaturated Fatty Acids Arachidonic Acid and Docosahexaenoic Acid Induce Mouse Dendritic Cells Maturation but Reduce T-Cell Responses In Vitro

    Carlsson, Johan A.; Wold, Agnes E.; Sandberg, Ann-Sofie; Östman, Sofia M.

    2015-01-01

    Long-chain polyunsaturated fatty acids (PUFAs) might regulate T-cell activation and lineage commitment. Here, we measured the effects of omega-3 (n-3), n-6 and n-9 fatty acids on the interaction between dendritic cells (DCs) and naïve T cells. Spleen DCs from BALB/c mice were cultured in vitro with ovalbumin (OVA) with 50 μM fatty acids; α-linolenic acid, arachidonic acid (AA), eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA), linoleic acid or oleic acid and thereafter OVA-specific DO11.10 T cells were added to the cultures. Fatty acids were taken up by the DCs, as shown by gas chromatography analysis. After culture with arachidonic acid or DHA CD11c+ CD11b+ and CD11c+ CD11bneg DCs expressed more CD40, CD80, CD83, CD86 and PDL-1, while IAd remained unchanged. However, fewer T cells co-cultured with these DCs proliferated (CellTrace Violetlow) and expressed CD69 or CD25, while more were necrotic (7AAD+). We noted an increased proportion of T cells with a regulatory T cell (Treg) phenotype, i.e., when gating on CD4+ FoxP3+ CTLA-4+, CD4+ FoxP3+ Helios+ or CD4+ FoxP3+ PD-1+, in co-cultures with arachidonic acid- or DHA-primed DCs relative to control cultures. The proportion of putative Tregs was inversely correlated to T-cell proliferation, indicating a suppressive function of these cells. With arachidonic acid DCs produced higher levels of prostaglandin E2 while T cells produced lower amounts of IL-10 and IFNγ. In conclusion arachidonic acid and DHA induced up-regulation of activation markers on DCs. However arachidonic acid- and DHA-primed DCs reduced T-cell proliferation and increased the proportion of T cells expressing FoxP3, indicating that these fatty acids can promote induction of regulatory T cells. PMID:26619195

  13. Aluminum chloride restoration of in situ leached uranium ores

    Grant, D.C.; Burgman, M.A.

    1982-01-01

    During in situ uranium mining using ammonium bicarbonate lixiviant, the ammonium exchanges with cations on the ore's clay. After mining is complete, the ammonium may desorb into post-leach ground water. For the particular ore studied, other chemicals (i.e., uranium and selenium) which are mobilized during the leach process, have also been found in the post-leach ground water. Laboratory column tests, used to simulate the leaching process, have shown that aluminum chloride can rapidly remove ammonium from the ore and thus greatly reduce the subsequent ammonium leakage level into ground water. The aluminum chloride has also been found to reduce the leakage levels of uranium and selenium. In addition, the aluminum chloride treatment produces a rapid improvement in permeability

  14. Optimization and validation of a chemical process for uranium, mercury and cesium leaching from cemented radioactive wastes

    Reynier, N.; Lastra, R.; Laviolette, C.; Bouzoubaa, N., E-mail: nicolas.reynier@canada.ca [Natural Resources Canada, CanmetMINING, Ottawa, Ontario (Canada); Chapman, M. [Canadian Nuclear Laboratories, Chalk River, Ontario (Canada)

    2015-12-15

    Canadian Nuclear Laboratories (CNL) is developing a treatment and long-term management strategy for a legacy cemented radioactive waste that contains uranium, mercury, and fission products. Extracting the uranium would be advantageous for decreasing the waste classification and reducing the cost of long-term management. The chemical leachability of 3 key elements (U, Hg, and Cs) from a surrogate cemented waste (SCW) was studied with several lixiviants. The results showed that the most promising approach to leach and recover U, Hg, and Cs is the direct leaching of the SCW with H{sub 2}SO{sub 4} in strong saline media. Operating parameters such as particle size, temperature, pulp density, leaching time, acid and salt concentrations, number of leaching/washing steps, etc. were optimized to improve key elements solubilization. Sulfuric leaching in saline media of a SCW (U5) containing 1182 ppm of U, 1598 ppm of Hg, and 7.9 ppm of Cs in the optimized conditions allows key elements solubilisation of 98.5 ± 0.4%, 96.6 ± 0.1%, and 93.8 ± 1.1% of U, Hg, and Cs, respectively. This solubilization process was then applied in triplicate to 7 other SCWs prepared with different cements, liquid ratios, and at different aging times and temperatures. Concentrated sulfuric acid is added to the slurry until the pH is about 2, which causes the complete degradation of cement and the formation of CaSO{sub 4}. Sulfuric acid is particularly useful because it produces a leachate that is amenable to conventional ion exchange technology for the separation and recovery of uranium. (author)

  15. Functional improvement of Saccharomyces cerevisiae to reduce volatile acidity in wine.

    Luo, Zongli; Walkey, Christopher J; Madilao, Lufiani L; Measday, Vivien; Van Vuuren, Hennie J J

    2013-08-01

    Control of volatile acidity (VA) is a major issue for wine quality. In this study, we investigated the production of VA by a deletion mutant of the fermentation stress response gene AAF1 in the budding yeast Saccharomyces cerevisiae. Fermentations were carried out in commercial Chardonnay grape must to mimic industrial wine-making conditions. We demonstrated that a wine yeast strain deleted for AAF1 reduced acetic acid levels in wine by up to 39.2% without increasing the acetaldehyde levels, revealing a potential for industrial application. Deletion of the cytosolic aldehyde dehydrogenase gene ALD6 also reduced acetic acid levels dramatically, but increased the acetaldehyde levels by 41.4%, which is not desired by the wine industry. By comparison, ALD4 and the AAF1 paralog RSF2 had no effects on acetic acid production in wine. Deletion of AAF1 was detrimental to the growth of ald6Δ and ald4Δald6Δ mutants, but had no effect on acetic acid production. Overexpression of AAF1 dramatically increased acetic acid levels in wine in an Ald6p-dependent manner, indicating that Aaf1p regulates acetic acid production mainly via Ald6p. Overexpression of AAF1 in an ald4Δald6Δ strain produced significantly more acetic acid in wine than the ald4Δald6Δ mutant, suggesting that Aaf1p may also regulate acetic acid synthesis independently of Ald4p and Ald6p. © 2013 Federation of European Microbiological Societies. Published by John Wiley & Sons Ltd. All rights reserved.

  16. Defining Effective Salt Leaching Regions Between Drains

    ANAPALI, Ömer; ŞAHİN, Üstün; ÖZTAŞ, Taşkın; HANAY, Abdurrahman

    2014-01-01

    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...

  17. Comparison of methods for the determination of reduced inorganic sulphur in acid sulphate soils

    Santomartino, S.L.

    1999-01-01

    Full text: The management of acid sulphate soils requires analytical methods that provide accurate data on the quantity of reduced inorganic sulphur within a soil, as it is this fraction that produces acid upon oxidation. This study uses sulphidic Coode Island Silt samples to compare common analytical methods including POCAS (Peroxide Oxidation-Combined Acidity and Sulphate) which consists of TSA (Total Sulphidic Acidity), S pos (Peroxide Oxidisable Sulphur), TOS (Total Oxidisable Sulphur) and chromium-reducible sulphur. The determination of total sulphur by Leco sulphur is strongly correlated with, but slightly less than, that analysed by XRF. Comparison of soil sulphide content by chromium-reducible sulphur, TSA and TOS methods indicates that TOS values are substantially higher than both other methods. The problem with the TOS method lies in the sulphate extraction procedure. Hot distilled water and HCI are commonly used as extractants, however hot distilled water fails to remove organic sulphur, thereby overestimating the sulphide content of the soil. Leco carbon analyses verify that a substantial proportion of organic matter exists within the samples. The HCI extraction process, which uses Ion Chromatography to analyse for sulphate, produces highly inaccurate results due to the interference of the sulphate peak by the chloride peak during analysis. An alternative method involving HCI extraction and XRF analysis of the soil residue is currently being undertaken. The use of KCI to extract sulphate generally produces values similar to the hot distilled water method. The sulphidic content measured by TSA is strongly correlated with, but slightly higher than that determined by the chromium-reducible sulphur method. This is attributed to the use of hydrogen peroxide in the TSA method, which oxidises organic matter to organic acids in addition to oxidising sulphides. These preliminary findings indicate that the chromium-reducible sulphur method is the most suitable

  18. Evaluation and selection of in-situ leaching mining method using analytic hierarchy process

    Zhao Heyong; Tan Kaixuan; Liu Huizhen

    2007-01-01

    According to the complicated conditions and main influence factors of in-situ leaching min- ing, a model and processes of analytic hierarchy are established for evaluation and selection of in-situ leaching mining methods based on analytic hierarchy process. Taking a uranium mine in Xinjiang of China for example, the application of this model is presented. The results of analyses and calculation indicate that the acid leaching is the optimum project. (authors)

  19. Mechanistic study of lead desorption during the leaching process of ion-absorbed rare earths: pH effect and the column experiment

    Xue, Q.; Tang, J., Sr.; Chen, H.

    2017-12-01

    High concentrations of ammonium sulfate, often used in the in-situ mining process, can result in a decrease of pH in the environment and dissolution of rare earth metals. Ammonium sulfate can also cause desorption of toxic heavy metals, leading to environmental and human health implications. In this study, the desorption behavior and fraction changes of lead in the ion-absorbed rare earth ore were studied using batch desorption experiments and column leaching tests. Results from batch desorption experiments showed that the desorption process of lead included fast and slow stages, and followed an Elovich model well. The desorption rate and the proportion of lead content in the solution to the total lead in the soil were observed to increase with a decrease in the initial pH of the ammonium sulfate solution. The lead in soil included an acid extractable fraction, reducible fraction, oxidizable fraction, and a residual fraction, with the predominant fractions being the reducible and acid extractable fractions. 96% of the extractable fraction in soil were desorbed into solution at pH=3.0, and the content of the reducible fraction was observed to initially increase (when pH>4.0) and then decrease (when pHleaching tests indicated that the content of lead in the different fractions of soil followed the trend of reducible fraction > oxidizable fraction > acid extractable fraction > residual fraction after the simulating leaching mining process. The change in pH was also found to have a larger influence on the acid extractable and reducible fractions than the other two fractions. The proportion of the extractable fraction being leached was ca. 86%, and the reducible fraction was enriched along the migration direction of the leaching liquid. These results suggest that certain lead fractions may desorb again and contaminate the environment via acid rain, which provides significant information for environmental assessment and remediation after mining process.

  20. Alkaline leaching of coal by the mechanochemical treatment

    Turèániová ¼udmila

    1998-09-01

    Full Text Available The possibility of application of a new process GACL (Grinding and Aqueous Caustic Leaching for the reduction of mineral components in the brown coal Nováky was tested. The simultaneous grinding and chemical leaching enable us to extract 41 % total sulphur, 95 % arsenic and to reduce the ash content to 43 %. The process proceeds at the atmospheric pressure, temperature 90oC and in diluted NaOH solutions (5 %.

  1. Technique for in situ leach simulation of uranium ores

    Grant, D.C.; Seidel, D.C.; Nichols, I.L.

    1985-01-01

    In situ uranium mining offers the advantages of minimal environmental disturbance, low capital and operating costs, and reduced mining development time. It is becoming an increasingly attractive mining method for the recovery of uranium from secondary ore deposits. In order to better understand the process, a laboratory technique was developed and used to study and simulate both the chemical and physical phenomena occurring in ore bodies during in situ leaching. The laboratory simulation technique has been used to determine effects of leaching variables on permeability, uranium recovery, and post-leach aquifer restoration. This report describes the simulation system and testing procedure in sufficient detail to allow the construction of the system, and to perform the desired leaching tests. With construction of such a system, in situ leaching of a given ore using various leach conditions can be evaluated relatively rapidly in the laboratory. Not only could optimum leach conditions be selected for existing ore bodies, but also exploitation of new ore bodies could be accelerated. 8 references, 8 figures, 2 tables

  2. To accelerate technology of in situ leaching and heap leaching for mining mineral resources of China

    Luo Mei

    1999-01-01

    Recently, in situ leaching and heap leaching are the most advanced technology for mining low-grade mineral resources in the world. The author briefly expounds the basic concept and advantages of in situ leaching and heap leaching and deals with the main research content of the hydrometallurgical technology of in situ leaching and heap leaching, its development and present application at home and abroad. Having expounded the gap existing between China's technology of in situ leaching and heap leaching and the foreign technology, the author forecasts the prospects of accelerating the mining of China's mineral resources by using the technology of in situ leaching and heap leaching

  3. Tranexamic acid reduces blood loss in patients with extracapsular fractures of the hip

    Tengberg, P T; Foss, N B; Palm, H

    2016-01-01

    AIMS: We chose unstable extra-capsular hip fractures as our study group because these types of fractures suffer the largest blood loss. We hypothesised that tranexamic acid (TXA) would reduce total blood loss (TBL) in extra-capsular fractures of the hip. PATIENTS AND METHODS: A single...

  4. Combined Intra-Articular and Intravenous Tranexamic Acid Reduces Blood Loss in Total Knee Arthroplasty

    Nielsen, Christian Skovgaard; Jans, Øivind; Ørsnes, Thue

    2016-01-01

    BACKGROUND: In total knee arthroplasty, both intravenous (IV) and intra-articular (IA) administration of tranexamic acid (TXA) have been shown to reduce blood loss in several randomized controlled trials, although routine use of systemic TXA is considerably more common. However, to our knowledge...

  5. Mine Waste Technology Program. In Situ Source Control Of Acid Generation Using Sulfate-Reducing Bacteria

    This report summarizes the results of the Mine Waste Technology Program (MWTP) Activity III, Project 3, In Situ Source Control of Acid Generation Using Sulfate-Reducing Bacteria, funded by the U.S. Environmental Protection Agency (EPA) and jointly administered by EPA and the U.S....

  6. Reducing and verifying haloacetic acids in treated drinking water using a biological filter system.

    Lou, Jie C; Chan, Hung Y; Yang, Chih Y; Tseng, Wei B; Han, Jia Y

    2014-01-01

    This study focused on reducing the haloacetic acid (HAA) concentrations in treated drinking water. HAA has been thought to be one possible nutrient supporting heterotrophic bacteria regrowth in drinking water. In this study, experiments were conducted using a pilot-scale system to evaluate the efficiency of biological filters (BF) for reducing excess HAA concentrations in water. The BF system reduced the total HAA concentration and the concentrations of five HAA species in the water. Dichloroacetic acid (DCAA), monobromoacetic acid (MBAA) and dibromoacetic acid (DBAA) were the three main HAA5 species that were present in the treated drinking water in this investigation. Combined, these three species represent approximately 77% of the HAA5 in the finished water after BF. The verification of the empirical HAA equation for the outlet in the BF system indicated linear relationships with high correlation coefficients. The empirical equation for the HAA5 concentrations in the finished water was established by examining other nutrients (e.g., dissolved organic carbon (DOC), ultraviolet absorbance at 254 nm wavelength (UV254), and ammonia nitrogen) that can reduce pathogenic contamination. These findings may be useful for designing advanced processes for conventional water treatment plants or for managing water treatment and distribution systems for providing high-quality drinking water.

  7. The Nonsteroidal Anti-inflammatory Drug Diclofenac Reduces Acid-Induced Heartburn Symptoms in Healthy Volunteers.

    Kondo, Takashi; Oshima, Tadayuki; Tomita, Toshihiko; Fukui, Hirokazu; Okada, Hiroki; Watari, Jiro; Miwa, Hiroto

    2015-07-01

    We investigated the effects of diclofenac, a nonsteroidal anti-inflammatory drug that inhibits prostaglandin production, on induction of esophageal sensation by acid perfusion in healthy men. We performed a prospective, double-blind, placebo-controlled, 2-period, cross-over study over 3 visits in 12 healthy men. Diclofenac was given 6 hours and 2 hours before an acid perfusion test. During the test, hydrochloric acid (0.15 mol/L) was perfused into the lower esophagus for 30 minutes; we evaluated upper gastrointestinal symptoms using a validated categoric rating scale. Then, we calculated and assessed the acid perfusion sensitivity score (APSS). Biopsy specimens were collected by endoscopy of the distal esophagus before and after acid perfusion; levels of prostaglandin E2 (PGE2) (pg/mg) were measured in the samples using an enzyme-linked immunosorbent assay. Compared with placebo, diclofenac significantly reduced the APSS for heartburn (82.2 ± 12.2 for placebo and 47.5 ± 8.9 for diclofenac; P heartburn was reduced significantly by diclofenac. Compared with placebo, diclofenac reduced the overproduction of PGE2 by esophageal tissues after acid perfusion (23.3 ± 5.2 for placebo and 11.4 ± 3.5 for diclofenac; P heartburn and esophageal levels of PGE2 (r = 0.53; P heartburn vs PGE2). Diclofenac attenuated acid-induced heartburn by inhibiting PGE2 overproduction in the esophagus. Esophageal PGE2 might be involved in producing heartburn symptoms. Clinical Trials Registry no: UMIN000014595. Copyright © 2015 AGA Institute. Published by Elsevier Inc. All rights reserved.

  8. Lactic acid fermentation of human urine to improve its fertilizing value and reduce odour emissions.

    Andreev, N; Ronteltap, M; Boincean, B; Wernli, M; Zubcov, E; Bagrin, N; Borodin, N; Lens, P N L

    2017-08-01

    During storage of urine, urea is biologically decomposed to ammonia, which can be lost through volatilization and in turn causes significant unpleasant smell. In response, lactic acid fermentation of urine is a cost-effective technique to decrease nitrogen volatilization and reduce odour emissions. Fresh urine (pH = 5.2-5.3 and NH 4 + -N = 1.2-1.3 g L -1 ) was lacto-fermented for 36 days in closed glass jars with a lactic acid bacterial inoculum from sauerkraut juice and compared to untreated, stored urine. In the lacto-fermented urine, the pH was reduced to 3.8-4.7 and the ammonium content by 22-30%, while the pH of the untreated urine rose to 6.1 and its ammonium content increased by 32% due to urea hydrolysis. The concentration of lactic acid bacteria in lacto-fermented urine was 7.3 CFU ml -1 , suggesting that urine is a suitable growth medium for lactic acid bacteria. The odour of the stored urine was subjectively perceived by four people to be twice as strong as that of lacto-fermented samples. Lacto-fermented urine induced increased radish germination compared to stored urine (74-86% versus 2-31%). Adding a lactic acid bacterial inoculum to one week old urine in the storage tanks in a urine-diverting dry toilet reduced the pH from 8.9 to 7.7 after one month, while the ammonium content increased by 35%, probably due to the high initial pH of the urine. Given that the hydrolyzed stale urine has a high buffering capacity, the lactic acid bacterial inoculum should be added to the urine storage tank of a UDDT before urine starts to accumulate there to increase the efficiency of the lactic acid fermentation. Copyright © 2017 Elsevier Ltd. All rights reserved.

  9. Reducing the acidity of Arabica coffee beans by ohmic fermentation technology

    Reta

    2017-07-01

    Full Text Available Coffee is widely consumed not only because of its typical taste, but coffee has antioxidant properties because of its polygons, and it stimulates brain performance. The main problem with the consumption of coffee is its content of caffeine. Caffeine when consumed in excess, can increase muscle tension, stimulate the heart, and increase the secretion of gastric acid. In this research, we applied ohmic fermentation technology, which is specially designed to mimic the stomach. Arabica coffee has high acidity that needs to be reduced than Luwak coffee, although it is cheaper. Hence, the ohmic technology with a time and temperature variation were applied to measure the total acidity of the coffee to determine optimum fermentation conditions. Results revealed that the total acidity of the coffee varied with fermentation conditions (0.18% – 0.73%. Generally, the longer the fermentation and the higher the temperature, the lower the total acidity. The acidity of the Luwak coffee through natural fermentation was 2.34%, which is substantially higher than the total acidity from the ohmic samples. Ohmic-based fermentation technology, therefore, offers improvements in coffee quality.

  10. Lauric acid as feed additive - An approach to reducing Campylobacter spp. in broiler meat.

    Zeiger, Katrin; Popp, Johanna; Becker, André; Hankel, Julia; Visscher, Christian; Klein, Guenter; Meemken, Diana

    2017-01-01

    The increasing prevalence of Campylobacter spp. within broiler populations is a major problem for food safety and consumer protection worldwide. In vitro studies could already demonstrate that Campylobacter spp. are susceptible to lauric acid. The purpose of this study was to examine in vivo the influence of lauric acid as a feed additive on slaughter parameters, muscle fatty acid profile, meat quality traits and the reduction of Campylobacter coli in inoculated meat of Ross 308 (R308) and Hubbard JA 757 (HJA) broilers in three independent trials (n = 3). Although slaughter parameters did not show any significant differences, the fatty acid profile of both breeds revealed significantly higher lauric acid concentrations (P meat quality traits showed no differences in the R308 breed (P > 0.05), but HJA test broilers had higher values for drip loss, electrical conductivity, CIE color values L* and b*, and lower pH values. The inoculation trials of R308 showed that initial bacterial loads of 5.9 log10 cfu/g were reduced during six days of storage (4°C) to approximately 4.3 log10 cfu/g in the control groups compared to 3.5 log10 cfu/g in the treatment groups (P = 0.0295), which could be due to antimicrobial effects of lauric acid within the muscle. This study therefore suggests that lauric acid as a feed additive has the potential to improve food safety by reducing the numbers of Campylobacter coli in broiler meat. However, this effect seems to be dependent on the breed determining the feed intake capacity, the fat deposition and therefore the ability to incorporate lauric acid in the muscle.

  11. Lauric acid as feed additive - An approach to reducing Campylobacter spp. in broiler meat.

    Katrin Zeiger

    Full Text Available The increasing prevalence of Campylobacter spp. within broiler populations is a major problem for food safety and consumer protection worldwide. In vitro studies could already demonstrate that Campylobacter spp. are susceptible to lauric acid. The purpose of this study was to examine in vivo the influence of lauric acid as a feed additive on slaughter parameters, muscle fatty acid profile, meat quality traits and the reduction of Campylobacter coli in inoculated meat of Ross 308 (R308 and Hubbard JA 757 (HJA broilers in three independent trials (n = 3. Although slaughter parameters did not show any significant differences, the fatty acid profile of both breeds revealed significantly higher lauric acid concentrations (P 0.05, but HJA test broilers had higher values for drip loss, electrical conductivity, CIE color values L* and b*, and lower pH values. The inoculation trials of R308 showed that initial bacterial loads of 5.9 log10 cfu/g were reduced during six days of storage (4°C to approximately 4.3 log10 cfu/g in the control groups compared to 3.5 log10 cfu/g in the treatment groups (P = 0.0295, which could be due to antimicrobial effects of lauric acid within the muscle. This study therefore suggests that lauric acid as a feed additive has the potential to improve food safety by reducing the numbers of Campylobacter coli in broiler meat. However, this effect seems to be dependent on the breed determining the feed intake capacity, the fat deposition and therefore the ability to incorporate lauric acid in the muscle.

  12. Development of an accelerated leaching method for incineration bottom ash correlated to toxicity characteristic leaching protocol.

    Lin, Shengxuan; Zhou, Xuedong; Ge, Liya; Ng, Sum Huan; Zhou, Xiaodong; Chang, Victor Wei-Chung

    2016-10-01

    Heavy metals and some metalloids are the most significant inorganic contaminants specified in toxicity characteristic leaching procedure (TCLP) in determining the safety of landfills or further utilization. As a consequence, a great deal of efforts had been made on the development of miniaturized analytical devices, such as Microchip Electrophoresis (ME) and μTAS for on-site testing of heavy metals and metalloids to prevent spreading of those pollutants or decrease the reutilization period of waste materials such as incineration bottom ash. However, the bottleneck lied in the long and tedious conventional TCLP that requires 18 h of leaching. Without accelerating the TCLP process, the on-site testing of the waste material leachates was impossible. In this study, therefore, a new accelerated leaching method (ALM) combining ultrasonic assisted leaching with tumbling was developed to reduce the total leaching time from 18 h to 30 min. After leaching, the concentrations of heavy metals and metalloids were determined with ICP-MS or ICP-optical emission spectroscopy. No statistical significance between ALM and TCLP was observed for most heavy metals (i.e., cobalt, manganese, mercury, molybdenum, nickel, silver, strontium, and tin) and metalloids (i.e., arsenic and selenium). For the heavy metals with statistical significance, correlation factors derived between ALM and TCLP were 0.56, 0.20, 0.037, and 0.019 for barium, cadmium, chromium, and lead, respectively. Combined with appropriate analytical techniques (e.g., ME), the ALM can be applied to rapidly prepare the incineration bottom ash samples as well as other environmental samples for on-site determination of heavy metals and metalloids. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  13. A reduced amino acid alphabet for understanding and designing protein adaptation to mutation.

    Etchebest, C; Benros, C; Bornot, A; Camproux, A-C; de Brevern, A G

    2007-11-01

    Protein sequence world is considerably larger than structure world. In consequence, numerous non-related sequences may adopt similar 3D folds and different kinds of amino acids may thus be found in similar 3D structures. By grouping together the 20 amino acids into a smaller number of representative residues with similar features, sequence world simplification may be achieved. This clustering hence defines a reduced amino acid alphabet (reduced AAA). Numerous works have shown that protein 3D structures are composed of a limited number of building blocks, defining a structural alphabet. We previously identified such an alphabet composed of 16 representative structural motifs (5-residues length) called Protein Blocks (PBs). This alphabet permits to translate the structure (3D) in sequence of PBs (1D). Based on these two concepts, reduced AAA and PBs, we analyzed the distributions of the different kinds of amino acids and their equivalences in the structural context. Different reduced sets were considered. Recurrent amino acid associations were found in all the local structures while other were specific of some local structures (PBs) (e.g Cysteine, Histidine, Threonine and Serine for the alpha-helix Ncap). Some similar associations are found in other reduced AAAs, e.g Ile with Val, or hydrophobic aromatic residues Trp with Phe and Tyr. We put into evidence interesting alternative associations. This highlights the dependence on the information considered (sequence or structure). This approach, equivalent to a substitution matrix, could be useful for designing protein sequence with different features (for instance adaptation to environment) while preserving mainly the 3D fold.

  14. Altered fatty acid metabolism and reduced stearoyl-coenzyme a desaturase activity in asthma.

    Rodriguez-Perez, N; Schiavi, E; Frei, R; Ferstl, R; Wawrzyniak, P; Smolinska, S; Sokolowska, M; Sievi, N A; Kohler, M; Schmid-Grendelmeier, P; Michalovich, D; Simpson, K D; Hessel, E M; Jutel, M; Martin-Fontecha, M; Palomares, O; Akdis, C A; O'Mahony, L

    2017-11-01

    Fatty acids and lipid mediator signaling play an important role in the pathogenesis of asthma, yet this area remains largely underexplored. The aims of this study were (i) to examine fatty acid levels and their metabolism in obese and nonobese asthma patients and (ii) to determine the functional effects of altered fatty acid metabolism in experimental models. Medium- and long-chain fatty acid levels were quantified in serum from 161 human volunteers by LC/MS. Changes in stearoyl-coenzyme A desaturase (SCD) expression and activity were evaluated in the ovalbumin (OVA) and house dust mite (HDM) murine models. Primary human bronchial epithelial cells from asthma patients and controls were evaluated for SCD expression and activity. The serum desaturation index (an indirect measure of SCD) was significantly reduced in nonobese asthma patients and in the OVA murine model. SCD1 gene expression was significantly reduced within the lungs following OVA or HDM challenge. Inhibition of SCD in mice promoted airway hyper-responsiveness. SCD1 expression was suppressed in bronchial epithelial cells from asthma patients. IL-4 and IL-13 reduced epithelial cell SCD1 expression. Inhibition of SCD reduced surfactant protein C expression and suppressed rhinovirus-induced IP-10 secretion, which was associated with increased viral titers. This is the first study to demonstrate decreased fatty acid desaturase activity in humans with asthma. Experimental models in mice and human epithelial cells suggest that inhibition of desaturase activity leads to airway hyper-responsiveness and reduced antiviral defense. SCD may represent a new target for therapeutic intervention in asthma patients. © 2017 EAACI and John Wiley and Sons A/S. Published by John Wiley and Sons Ltd.

  15. Disposal of leached residual in heap leaching by neutralization

    Wang Jingmin

    1993-01-01

    The disposal results of leached residual with lime are described. Using the ratio of residual to lime being 100 : 1 the ideal disposal results were obtained with the effluent of the neutralized residual close to neutral

  16. Thyroid hormone reduces PCSK9 and stimulates bile acid synthesis in humans[S

    Bonde, Ylva; Breuer, Olof; Lütjohann, Dieter; Sjöberg, Stefan; Angelin, Bo; Rudling, Mats

    2014-01-01

    Reduced plasma LDL-cholesterol is a hallmark of hyperthyroidism and is caused by transcriptional stimulation of LDL receptors in the liver. Here, we investigated whether thyroid hormone (TH) actions involve other mechanisms that may also account for the reduction in LDL-cholesterol, including effects on proprotein convertase subtilisin/kexin type 9 (PCSK9) and bile acid synthesis. Twenty hyperthyroid patients were studied before and after clinical normalization, and the responses to hyperthyroidism were compared with those in 14 healthy individuals after 14 days of treatment with the liver-selective TH analog eprotirome. Both hyperthyroidism and eprotirome treatment reduced circulating PCSK9, lipoprotein cholesterol, apoB and AI, and lipoprotein(a), while cholesterol synthesis was stable. Hyperthyroidism, but not eprotirome treatment, markedly increased bile acid synthesis and reduced fibroblast growth factor (FGF) 19 and dietary cholesterol absorption. Eprotirome treatment, but not hyperthyroidism, reduced plasma triglycerides. Neither hyperthyroidism nor eprotirome treatment altered insulin, glucose, or FGF21 levels. TH reduces circulating PSCK9, thereby likely contributing to lower plasma LDL-cholesterol in hyperthyroidism. TH also stimulates bile acid synthesis, although this response is not critical for its LDL-lowering effect. PMID:25172631

  17. Residues leaching from 'Factory of barren ores'

    Rakhmatov, N.; Khakimov, N.; Nazarov, Kh.M.; Barotov, A.M.

    2012-01-01

    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 H 2 SO 4 176,54 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 60 d eg C a nd 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.

  18. Mechanism for elevated temperature leaching

    Kenna, B.T.; Murphy, K.D.

    1979-01-01

    Long-term, elevated temperature leaching and subsequent electron microprobe analysis of simulated waste glass and ceramic materials have been completed. A cyclic leaching pattern was found in all systems over a 20-month period. It appears that the leaching of mobile ions by simple diffusional processes is modified by more complex chemical interactions. The release of immobile ions is primarily a function of their chemical interactions in the matrix which suggests that these ions may be complex species when released into solution. A mechanism is proposed which incorporates these ideas and the cyclic phenomenon observed

  19. 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...

  20. Hypertonic saline reduces inflammation and enhances the resolution of oleic acid induced acute lung injury

    Costello Joseph F

    2008-07-01

    Full Text Available Abstract Background Hypertonic saline (HTS reduces the severity of lung injury in ischemia-reperfusion, endotoxin-induced and ventilation-induced lung injury. However, the potential for HTS to modulate the resolution of lung injury is not known. We investigated the potential for hypertonic saline to modulate the evolution and resolution of oleic acid induced lung injury. Methods Adult male Sprague Dawley rats were used in all experiments. Series 1 examined the potential for HTS to reduce the severity of evolving oleic acid (OA induced acute lung injury. Following intravenous OA administration, animals were randomized to receive isotonic (Control, n = 12 or hypertonic saline (HTS, n = 12, and the extent of lung injury assessed after 6 hours. Series 2 examined the potential for HTS to enhance the resolution of oleic acid (OA induced acute lung injury. Following intravenous OA administration, animals were randomized to receive isotonic (Control, n = 6 or hypertonic saline (HTS, n = 6, and the extent of lung injury assessed after 6 hours. Results In Series I, HTS significantly reduced bronchoalveolar lavage (BAL neutrophil count compared to Control [61.5 ± 9.08 versus 102.6 ± 11.89 × 103 cells.ml-1]. However, there were no between group differences with regard to: A-a O2 gradient [11.9 ± 0.5 vs. 12.0 ± 0.5 KPa]; arterial PO2; static lung compliance, or histologic injury. In contrast, in Series 2, hypertonic saline significantly reduced histologic injury and reduced BAL neutrophil count [24.5 ± 5.9 versus 46.8 ± 4.4 × 103 cells.ml-1], and interleukin-6 levels [681.9 ± 190.4 versus 1365.7 ± 246.8 pg.ml-1]. Conclusion These findings demonstrate, for the first time, the potential for HTS to reduce pulmonary inflammation and enhance the resolution of oleic acid induced lung injury.

  1. Renewal of corrosion progress after long-term leaching

    Muller, I.

    1997-01-01

    Over the past 18 years a large inventory of glasses which have undergone leach testing has been built up at the Vitreous State Laboratory of The Catholic University of America. These glasses include a very wide range of compositions, most from actual mixed wastes and many natural analogs. A variety in the test protocol have been used, including PCT, ANSI, TCLP, IAEA, Flow, Soxhlet, MCC1, MCC3, and DIN. Many of these tests have been conducted for over a decade and are still ongoing. The progress of the tests is monitored by periodic sampling with fluid replacement. Twenty different leachants (including groundwaters, humic acid and pH buffers) have been employed. Occasionally, some of the glass is removed from the leaching vessels to observe the altered layers forming on the glass and to identify reaction products. Slight variations in the composition of the glass, subjected to PCT leaching, exhibit widely differing leaching behaviors. The evolution of leachate composition over time often shows a basically stable leach rate followed by a dramatic increase, with times of onset varying considerably, primarily as a function of glass composition. The same rapid rise in leachate has also been observe for a given glass composition studied at different S/V ratio. The study of such non-linearity in glass leaching is the subject of this review. (author)

  2. Comparison of leaching tests and study of leaching mechanisms

    Amarantos, S.G.; Papadokostaki, K.G.; Petropoulos, J.H.

    1985-10-01

    The present work is concerned first with the study of certain aspects of the leaching kinetics of Cs + and Sr ++ embedded in cement, as Cs 2 SO 4 and SrSO 4 , and in particular: (a) the comparative evaluation of leaching in (i) stagnant, (ii) stirred and (iii) continuously flowing (modified Soxhlet) water, (b) the effect of atmospheric CO 2 on elution, (c) the effect of temperature changes during leaching. Secondly, model kinetic studies were carried out using cellulose acetate incorporating SrSO 4 , CaSO 4 or NaCl. The main results obtained were: (1) Cs leaching rates were not significantly affected by the leaching method or by the presence of atmospheric CO 2 . The embedded Cs exists in relatively easily leachable and less rapidly leachable (most probably located within the gel regions) forms. (2) Elution of Sr is retarded by stagnant and infrequently renewed leachant (method (i)) and by the presence of atmospheric CO 2 ; leaching method (iii), which tends to minimize both of these effects, gave the highest elution rates. (3) The observed elution kinetics in the case of cellulose acetate-CaSO 4 or SrSO 4 conform to the Higuchi model, but a more elaborate theory is needed for the cellulose acetate-NaCl system. (author)

  3. LEACH-A: An Adaptive Method for Improving LEACH Protocol

    Jianli ZHAO

    2014-01-01

    Full Text Available Energy has become one of the most important constraints on wireless sensor networks. Hence, many researchers in this field focus on how to design a routing protocol to prolong the lifetime of the network. The classical hierarchical protocols such as LEACH and LEACH-C have better performance in saving the energy consumption. However, the choosing strategy only based on the largest residue energy or shortest distance will still consume more energy. In this paper an adaptive routing protocol named “LEACH-A” which has an energy threshold E0 is proposed. If there are cluster nodes whose residual energy are greater than E0, the node of largest residual energy is selected to communicated with the base station; When all the cluster nodes energy are less than E0, the node nearest to the base station is select to communication with the base station. Simulations show that our improved protocol LEACH-A performs better than the LEACH and the LEACH-C.

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

    Novak, Martin; Pacherova, Petra; Erbanova, Lucie; Veron, Alain J.; Buzek, Frantisek; Jackova, Ivana; Paces, Tomas; Rukavickova, Lenka; Blaha, Vladimir; Holecek, Jan

    2012-01-01

    Highlights: ► S and Pb isotopes are useful tracers of polluted groundwater movement. ► Large ranges of found δ 34 S and 206 Pb/ 207 Pb ratios made source apportionment robust. ► δ 34 S 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 (δ 34 S between +2.6 and +18.9‰; 206 Pb/ 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.

  5. Leaching behaviour of tritium from a hardened cement paste

    Matsuzuru, H.; Moriyama, N.; Ito, A.

    1979-01-01

    Leaching of tritium from a hardened cement paste into an aqueous phase has been studied to assess the safety of solidification of the tritiated liquid waste with cement. Leaching tests were carried out in accordance with the method recommended by the International Atomic Energy Agency. The leaching fraction was measured as functions of the waste-cement wt ratio (Wa/C), temperature of leachant and curing time. the tritium leachability of cements follows the order: alumina cement > Portland cement > slag cement. The fraction of tritium leached increases with increasing Wa/C and temperature and decreasing curing period. A deionized water as a leachant gives a slightly higher leachability than the synthetic sea water. The coating of the specimen surface with bitumen reduces the leachability to about 5% of its value for the specimen without coating. (author)

  6. In situ leaching of uranium in South Australia

    Matthews, D.

    1998-01-01

    The proposed two new uranium mines at Beverley and Honeymoon, South Australia plan to use the cheap but potentially polluting process of in situ leaching (ISL) and permission has already been given for experimental underground leaching at Beverley. The mining industry describes ISL as environmentally benign because, instead of excavating, a corrosive liquid such as sulphuric acid is used. The liquid, sometimes 10000 times more acid than the aquifer water, is pumped into the ground in order to leach out the uranium and the resulting solution is then pumped to the surface where the uranium is extracted. Because the groundwater is salty and radioactive, the mining companies regard it as useless, so its contamination by ISL is considered of no concern. Salty radioactive water can be purified or desalinated and such processes are commonly used by mining companies such as Western Mining Corporation at Roxby Downs. (author)

  7. Role of tranexamic acid in reducing blood loss during and after caesarean section

    Simran Kaur Bhatia

    2015-01-01

    Full Text Available Introduction: Association between caesarean section and intra operative and post operative bleeding is known. Post-partum hemorrhage is still a leading cause for maternal morbidity and mortality. This study will evaluate the efficacy and safety of tranexamic acid in reducing the blood loss after placental delivery following lower segment caesarean section (LSCS and note any adverse effects. Materials and Methods: A total of 100 women, who underwent elective or emergency primary caesarean section at term between 37 and 41 weeks have been studied prospectively. They were divided into two groups. In the study group of 50, tranexamic acid 1 gm IV was given 20 minutes before making incision for caesarean section and the control group of 50 did not receive tranexamic acid. Statistical Analysis: For quantitative outcomes, the t-test was used to test for difference in the two groups. For categorical outcomes, chi square and odds ratio with 95% confidence interval were used as applicable. Results: The patient characteristics, namely age, height, weight, gestational age and gravidity in two groups were similar which was statistically insignificant. Hemoglobin decreased slightly after birth in both groups but no statistical difference between two groups was noticed. There was no episode of thrombosis in the study. Tranexamic acid significantly reduced the quantity of the blood loss from time of placental delivery to 2 hours postpartum (P < 0.001 and from end of LSCS to 2 hours postpartum (P < 0.001. However, there was no statistical difference in quantity of blood loss from time of placental delivery to end of LSCS in both groups (P < 0.001. Conclusion: A safe dose of tranexamic acid has an effective role in reducing blood loss during LSCS without causing adverse reaction. Thus, drug can be used effectively in reducing maternal morbidity and mortality during LSCS.

  8. DOES TRANEXAMIC ACID REDUCE BLOOD LOSS IN OFF-PUMP CORONARY ARTERY BYPASS?

    A. Mehr-Aein

    2006-09-01

    Full Text Available Tranexamic acid is now used on a routine basis for on-pump coronary artery bypass grafting (CABG. We assessed the hemostatic effects of tranexamic acid to decrease bleeding tendency and transfusion requirements in patients undergoing off-pump coronary artery bypass surgery (OPCAB. A total of 66 patients were enrolled to elective OPCAB in a double-blind, prospective randomized study. Of these, 33 patients received tranexamic acid (15 mg/kg before the infusion of heparin and 15 mg/kg after protamin infusion, and 33 patients received only saline. Preoperative hematologic variables, postoperative bleeding and allogeneic transfusions were considered. D-dimer plasma levels were also evaluated to monitor the activation of fibrinolysis. Postoperative bleeding was significantly lower in the tranexamic acid group compared with the control group (320 ± 38 mL vs. 480 ± 75 mL at 12 hour, P < 0.001. The tranexamic acid group had significantly lesser need for allogeneic blood products (0.46 units/patients vs. 0.94 units/patients, P < 0.001. They had also lower post-operative D-dimer plasma levels. No postoperative thrombotic complications were observed in either group. The defective hemostasis occurs even in the OPCABG. Tranexamic acid effectively reduces postoperative blood loss and the need for allogeneic blood products after OPCAB is decreased.

  9. Selective leaching of Zn from spent alkaline batteries using environmentally friendly approaches.

    Maryam Sadeghi, S; Vanpeteghem, Guillaumme; Neto, Isabel F F; Soares, Helena M V M

    2017-02-01

    The main aim of this work was to evaluate the possibility of using microwave or ultrasound to assist the efficient and selective leaching of Zn from spent alkaline batteries and compare the results with those obtained using the conventional method. Two different strategies were applied: acid leaching of a washed residue and alkaline leaching of the original residue. In both (acid and alkaline) approaches, the use of microwave- or ultrasound-assisted leaching increased the extraction of Zn compared with the best results obtained using conventional leaching [acid leaching (1.5mol/L H 2 SO 4 , 3h, 80°C), 90% of Zn extracted; alkaline leaching (6mol/L NaOH, 3h, 80°C), 42% of Zn extracted]. With acid leaching, 94% of the Zn was extracted using microwave-assisted leaching (1 cycle, 30s, 1mol/L H 2 SO 4 ), and 92% of the Zn was extracted using ultrasound-assisted leaching (2min, 0.1p, 20% amplitude, 1mol/L H 2 SO 4 ). Ultrasound-assisted leaching resulted in a more selective (Zn/Mn ratio of 5.1) Zn extraction than microwave-assisted leaching (Zn/Mn ratio of 3.5); both processes generated a concentrated Zn solution (⩾18.7g/L) with a purity (83.3% and 77.7%, respectively) that was suitable for electrowinning. With alkaline leaching, microwave- (1 cycle, 3 min, 4mol/L NaOH) and ultrasound-assisted (14min, 0.1p, 20% amplitude, 4mol/L NaOH) leaching extracted about 80% of the Zn and less than 0.01% of the Mn, which resulted in lesser concentrated Zn solutions (approximately 16.5g/L) but with high purity (>99.5%) that was suitable for the recovery of Zn by precipitation. The microwave- and ultrasound-assisted leaching strategies used in this work proved to be efficient and environmentally-friendly approaches for the extraction of Zn from spent alkaline residues since a concentrated Zn solution with adequate purity for subsequent Zn recovery was obtained using significantly decreased leaching times and concentrations of chemicals. Copyright © 2017 Elsevier Ltd. All rights

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

    Kindler, Reimo; Siemens, Jan; Kaiser, Klaus

    2011-01-01

    ecosystem exchange (NEE) plus carbon inputs with fertilization minus carbon removal with harvest. Carbon leaching increased the net losses from cropland soils by 24–105% (median: 25%). For the majority of forest sites, leaching hardly affected actual net ecosystem carbon balances because of the small...... solubility of CO2 in acidic forest soil solutions and large NEE. Leaching of CH4 proved to be insignificant compared with other fluxes of carbon. Overall, our results show that leaching losses are particularly important for the carbon balance of agricultural systems....

  11. Measurement of chemical leaching potential of sulfate from landfill disposed sulfate containing wastes.

    Sun, Wenjie; Barlaz, Morton A

    2015-02-01

    A number of sulfate-containing wastes are disposed in municipal solid wastes (MSW) landfills including residues from coal, wood, and MSW combustion, and construction and demolition (C&D) waste. Under anaerobic conditions that dominate landfills, the sulfate can be reduced to hydrogen sulfide which is problematic for several reasons including its low odor threshold, toxicity, and corrosive nature. The overall objective of this study was to evaluate existing protocols for the quantification of total leachable sulfate from solid samples and to compare their effectiveness and efficiency with a new protocol described in this study. Methods compared include two existing acid extraction protocols commonly used in the U.S., a pH neutral protocol that requires multiple changes of the leaching solution, and a new acid extraction method. The new acid extraction method was shown to be simple and effective to measure the leaching potential of sulfate from a range of landfill disposed sulfate-containing wastes. However, the acid extraction methods do not distinguish between sulfate and other forms of sulfur and are thus most useful when sulfate is the only form of sulfur present. Copyright © 2014 Elsevier Ltd. All rights reserved.

  12. 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 ...

  13. Heavy metal leaching from mine tailings as affected by plants

    Zhu, D.; Schwab, A.P.; Banks, M.K.

    1999-12-01

    A column experiment was conducted to determine the impact of soil cover and plants on heavy metal leaching from mine tailings and heavy metal contaminated soil. Columns made of PVC were constructed with 30 cm subsoil covered by 30 cm of mine tailings followed by 0, 30, or 60 cm subsoil covered by 30 cm of mine tailings followed by 0, 30, or 60 cm of clean topsoil. Two grasses, tall fescue (Festuca arundinacea Schreb.) and big bluestem (Andropogon gerardii), were grown in the columns. The columns were leached at a slow rate for 1 yr with a 0.001 M CaCl{sub 2} solution under unsaturated conditions. The presence of both tall fescue and big bluestem increased Zn and Cd concentrations in the leachate. Lead concentrations in leachates were not affected by the presence of plants. Although plants generally reduced the total amount of water leached, total mass of Zn and Cd leached generally was not impacted by plants. Total mass of Pb leached was positively correlated with total leachate collected from each column. Covering the mine tailings with 60 cm of topsoil increased the mass of Zn and Cd leached relative to no topsoil. When the subsoil was absent, Zn and Cd leaching increased by as much as 20-fold, verifying the ability of soil to act as a sink for metals. Mine tailing remediation by establishing vegetation can reduce Pb movement but may enhance short-term Cd and Zn leaching. However, the changes were relatively small and do not outweigh the benefits of using vegetation in mine tailings reclamation.

  14. Chemical leaching of rapidly solidified Al-Si binary alloys

    Yamauchi, I.; Takahara, K.; Tanaka, T.; Matsubara, K.

    2005-01-01

    Various particulate precursors of Al 100-x Si x (x = 5-12) alloys were prepared by a rapid solidification process. The rapidly solidified structures of the precursors were examined by XRD, DSC and SEM. Most of Si atoms were dissolved into the α-Al(fcc) phase by rapid solidification though the solubility of Si in the α-Al phase is negligibly small in conventional solidification. In the case of 5 at.% Si alloy, a single α-Al phase was only formed. The amount of the primary Si phase increased with increase of Si content for the alloys beyond 8 at.% Si. Rapid solidification was effective to form super-saturated α-Al precursors. These precursors were chemically leached by using a basic solution (NaOH) or a hydrochloric acid (HCl) solution. All Al atoms were removed by a HCl solution as well as a NaOH solution. Granules of the Si phase were newly formed during leaching. The specific surface area was about 50-70 m 2 /g independent of Si content. The leaching behavior in both solutions was slightly different. In the case of a NaOH solution, the shape of the precursor often degenerated after leaching. On the other hand, it was retained after leaching by a HCl solution. Fine Si particles precipitated in the α-Al phase by annealing of as-rapidly solidified precursors at 773 K for 7.2 x 10 3 s. In this case, it was difficult to obtain any products by NaOH leaching, but a few of Si particles were obtained by HCl leaching. Precipitated Si particles were dissolved by the NaOH solution. The X-ray diffraction patterns of leached specimens showed broad lines of the Si phase and its lattice constant was slightly larger than that of the pure Si phase. The microstructures of the leached specimens were examined by transmission electron microscopy. It showed that the leached specimens had a skeletal structure composed of slightly elongated particles of the Si phase and quite fine pores. The particle size was about 30-50 nm. It was of comparable order with that evaluated by Scherer

  15. 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.

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

    Otero-Rey, Jose R.; Mato-Fernandez, Maria J.; Moreda-Pineiro, Jorge; Alonso-Rodriguez, Elia; Muniategui-Lorenzo, Soledad; Lopez-Mahia, Purificacion; Prada-Rodriguez, Dario

    2005-01-01

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

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

    Chen Shian; Huang Xiangfu; Fan Baotuan

    1995-01-01

    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 (MnO 2 40%) 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

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

    Deniz Turan, M.; Soner Altundoğan, H.

    2014-09-01

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

  19. Ethanolic extract of Piper betle Linn. leaves reduces nociception via modulation of arachidonic acid pathway.

    De, Soumita; Maroo, Niteeka; Saha, Piu; Hazra, Samik; Chatterjee, Mitali

    2013-01-01

    The objective of this study was to evaluate the peripheral analgesic effect of Piper betle leaf extract (PBE) along with establishing its putative mechanism of action. Male Swiss albino mice after pre-treatment (1 h) with different doses of PBE were injected 0.8% (v/v) acetic acid i.p.; the onset and number of writhes were noted up to 15 min. To evaluate the mechanism of action, the murine peritoneal exudate was incubated with PBE for 1 h, followed by exposure to arachidonic acid (AA) and generation of reactive oxygen species (ROS) was measured by flow cytometry using 2',7'-dichlorodihydrofluorescein diacetate. PBE in a dose dependent manner significantly reduced acetic acid induced writhing response in mice (P < 0.001). In peritoneal exudates, PBE significantly inhibited AA induced generation of ROS, P < 0.01. The present study indicates that PBE has promising analgesic activity, worthy of future pharmacological consideration.

  20. 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%. Copyright © 2015 Elsevier Ltd. All rights reserved.

  1. Nitrate Leaching, Yields and Carbon Sequestration after Noninversion Tillage, Catch Crops, and Straw Retention

    Hansen, Elly Møller; Munkholm, Lars Juhl; Olesen, Jørgen E

    2015-01-01

    retention did not significantly increase yields, nor did it reduce leaching, while fodder radish (Raphanus sativus L.) as a catch crop was capable of reducing nitrate leaching to a low level. Thus, YSL of winter wheat (Triticum aestivum L.) was higher than for spring barley (Hordeum vulgare L.) grown after...

  2. Experience with restoration of ore-bearing aquifers after in situ leach uranium mining

    Yazikov, V.G.; Zabaznov, V.U.

    2002-01-01

    In many cases the most important environmental issue for in situ leach uranium mining technology is the impact on groundwater. Usually the greatest issue is the chemical condition of the ore bearing aquifer following the completion of leaching. Based on experience gained during post leach monitoring, it has been found that in properly selected sites the impact following leaching is greatly reduced because of the process of self restoration, otherwise known as natural attenuation. This paper provides ground water monitoring data from 1985 to 1997 following completion of leaching at the Irkol uranium deposit, Kazakhstan. It shows the evolution of the pH, and other chemical parameters over this period. The monitoring results demonstrate that at this site the process of natural attenuation appears to have effectively reduced the impact on groundwater at the site, as well as to keep contaminated leaching fluids from moving more than a few hundreds of metres from the wellfield. (author)

  3. Thyroid hormone reduces PCSK9 and stimulates bile acid synthesis in humans[S

    Bonde, Ylva; Breuer, Olof; L?tjohann, Dieter; Sj?berg, Stefan; Angelin, Bo; Rudling, Mats

    2014-01-01

    Reduced plasma LDL-cholesterol is a hallmark of hyperthyroidism and is caused by transcriptional stimulation of LDL receptors in the liver. Here, we investigated whether thyroid hormone (TH) actions involve other mechanisms that may also account for the reduction in LDL-cholesterol, including effects on proprotein convertase subtilisin/kexin type 9 (PCSK9) and bile acid synthesis. Twenty hyperthyroid patients were studied before and after clinical normalization, and the responses to hyperthyr...

  4. [Single intravenous tranexamic acid dose to reduce blood loss in primary total knee replacement].

    Sanz-Reig, J; Parra Ruiz, B; Ferrández Martínez, J; Martínez López, J F

    2016-01-01

    To evaluate the effectiveness and safety of a single intravenous dose of tranexamic acid in order to reduce blood loss in total knee replacement. Prospective observational study of the administration of tranexamic acid in patients undergoing primary total knee arthroplasty from November 2013 to February 2015, in which an autologous blood recovery system was used. The study included 98 patients, distributed into two groups of 49 patients according to whether or not they received intravenous tranexamic acid. The primary endpoint was the number of patients requiring autologous transfusion from the recovery system autologous blood recovery system. No drop-outs were recorded during follow-up. There were no significant differences between groups as regards the preoperative and hospital variables. The mean preoperative haemoglobin and haematocrit at 24 and 48 hours postoperatively were similar in both groups. The average volume of bleeding in the autologous blood recovery system and estimated average blood loss was lower in patients who had been administered tranexamic acid, with significant differences. No patients in the group that was administered tranexamic acid required blood autotransfusion. The transfusion rate was zero in the two groups. No adverse events related to the administration of tranexamic acid were recorded. Intravenous administration of tranexamic acid, according to the described protocol, has presented a non-autotransfusion or allo-transfusion rate of 100%, with no increased incidence of thrombotic events. Thus, its use in this group of patients is recommended. The indication should be individualized, its use justified in the patient medical records, and informed consent is mandatory. Copyright © 2015 SECOT. Published by Elsevier Espana. All rights reserved.

  5. Process for in-situ leaching of uranium

    Espenscheid, W.F.; Yan, F.Y.

    1983-01-01

    The present invention relates to the recovery of uranium from subterranean ore deposits, and more particularly to an in-situ leaching operation employing an aqueous solution of sulfuric acid and carbon dioxide as the lixiviant. Uranium is solubilized in the lixiviant as it traverses the subterranean uranium deposit. The lixiviant is subsequently recovered and treated to remove the uranium

  6. Phosphorus leaching from cow manure patches on soil columns

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

    2007-01-01

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

  7. Environmental Hazard Assessment of Jarosite Waste Using Batch Leaching Tests

    M. Kerolli – Mustafa

    2018-01-01

    Full Text Available Jarosite waste samples from Trepça Zinc Industry in Kosovo were subjected to two batch leaching tests as an attempt to characterize the leaching behavior and mobility of minor and major elements of jarosite waste. To achieve this, deionized water and synthetic acidic rain leaching tests were employed. A two-step acidic treatment in microwave digestion system were used to dissolve jarosite waste samples, followed by determination of Al, Ag, As, Ba, Cd, Co, Cr, Cu, Fe, Mn, Ni, P, Pb, S, Si, Sr, and Zn by inductively coupled plasma optical emission spectrometry (ICP-OES. The validation of the procedure was performed by the analysis of two geochemical reference materials, S JR-3 and S Jsy-1. Two toxicity leaching tests revealed a high metal releasing of Cd, Cu, Ni, Mn, Pb, Zn, and As, and the metal release risk for these elements is still very high due the low pH and acid rain. The statistical analysis showed useful data information on the relationship between elements in jarosite samples in two different extraction conditions (deionized water and synthetic acid rain.

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

    Gutknecht, Toni; Gustafsson, Anna; Forsgren, Christer; 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

  9. 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.

  10. 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)

  11. Estimating Leaching Requirements for Barley Growth under Saline Irrigation

    Ahmed Al-Busaidi

    2012-01-01

    Full Text Available The utilization of marginal water resources for agriculture is receiving considerable attention. The lands irrigated with saline water are required to reduce salt accumulations through leaching and/or drainage practices. A field experiment was carried out to investigate the effect of saline irrigation and leaching fraction on barley (Hordeum vulgare L. growth. For this purpose highly saline water was diluted to the salinity levels of 3, 6 and 9 dS m-1 and applied by drip irrigation at 0.0, 0.15, 0.20 and 0.25 leaching fractions (LF. The results of the experiment showed that both quantity and quality of water regulated salts distribution within the soil in the following manner: a the salts were found higher near or immediate below the soil surface; b an enhanced LF carried more salts down the soil horizon but there was no significant difference in plant yield between different treatments of leaching fractions. Salinity of water significantly impaired barley growth. The good drainage of sandy soil enhanced the leaching process and minimized the differences between leaching fractions. The increment in saline treatments (3, 6 and 9 dS m-1 added more salts and stressed plant growth. However, the conjunctive use of marginal water at proportional LF could be effective in enhancing the yield potential of crops in water-scarce areas.

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

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

    2013-11-15

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

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

    Browne, James D.; Allen, Eoin; Murphy, Jerry D.

    2013-01-01

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

  14. Optimization and validation of a chemical process for uranium, mercury and cesium leaching from cemented radioactive wastes

    Reynier, N.; Riveros, P.; Lastra, R.; Laviolette, C.; Bouzoubaa, N.; Chapman, M.

    2015-01-01

    Atomic Energy of Canada Limited (AECL) is developing a treatment and long-term management strategy for a legacy cemented radioactive waste that contains uranium, mercury and fission products. Extracting the uranium would be advantageous for decreasing the waste classification and reducing the cost of long-term management. Consequently, there are safety and economic and environmental incentives for the extraction of uranium, mercury and cesium before subjecting the cemented waste to a stabilization process. The mineralogical analysis of the surrogate cemented waste (SCW) indicated that uranium forms calcium uranate, CaUO 4 , occurring as layers of several millimeters or as grains of 20 μm. Hg is found mostly as large (∼50 μm) and small grains (5-8 μm) of HgO. The chemical leachability of three key elements (U, Hg, and Cs) from a SCW was studied with several leaching materials. The results showed that the most promising approach to leach and recover U, Hg, and Cs is the direct leaching of the SCW with H 2 SO 4 in strong saline media. Operating parameters such as particle size, temperature, pulp density, leaching time, acid and salt concentrations, number of leaching/rinsing step, etc. were optimized to improve key elements solubilization. Sulfuric leaching in saline media of a SCW (U5) containing 1182 ppm of U, 1598 ppm of Hg, and 7.9 ppm of Cs in the optimized conditions allows key elements recovery of 98.5 ± 0.4%, 96.6 ± 0.1%, and 93.8 ± 1.1% of U, Hg, and Cs respectively. This solubilization process was then applied in triplicate to seven other SCW prepared with different cement, liquid ratio and at different aging time and temperature. Concentrated sulfuric acid is added to the slurry until the pH is about 2, which causes the complete degradation of cement and the formation of CaSO 4 . At this pH, the acid consumption is moderate and the formation of amorphous silica gel is avoided. Sulfuric acid is particularly useful because it produces a leachate that

  15. Novel Dental Cement to Combat Biofilms and Reduce Acids for Orthodontic Applications to Avoid Enamel Demineralization

    Ning Zhang

    2016-05-01

    Full Text Available Orthodontic treatments often lead to biofilm buildup and white spot lesions due to enamel demineralization. The objectives of this study were to develop a novel bioactive orthodontic cement to prevent white spot lesions, and to determine the effects of cement compositions on biofilm growth and acid production. 2-methacryloyloxyethyl phosphorylcholine (MPC, nanoparticles of silver (NAg, and dimethylaminohexadecyl methacrylate (DMAHDM were incorporated into a resin-modified glass ionomer cement (RMGI. Enamel shear bond strength (SBS was determined. Protein adsorption was determined using a micro bicinchoninic acid method. A dental plaque microcosm biofilm model with human saliva as inoculum was used to investigate metabolic activity, colony-forming units (CFU and lactic acid production. Incorporating 3% of MPC, 1.5% of DMAHDM, and 0.1% of NAg into RMGI, and immersing in distilled water at 37 °C for 30 days, did not decrease the SBS, compared to control (p > 0.1. RMGI with 3% MPC + 1.5% DMAHDM + 0.1% NAg had protein amount that was 1/10 that of control. RMGI with triple agents (MPC + DMAHDM + NAg had much stronger antibacterial property than using a single agent or double agents (p < 0.05. Biofilm CFU on RMGI with triple agents was reduced by more than 3 orders of magnitude, compared to commercial control. Biofilm metabolic activity and acid production were also greatly reduced. In conclusion, adding MPC + DMAHDM + NAg in RMGI substantially inhibited biofilm viability and acid production, without compromising the orthodontic bracket bond strength to enamel. The novel bioactive cement is promising for orthodontic applications to hinder biofilms and plaque buildup and enamel demineralization.

  16. Si-based technologies for reduction of the pollutant leaching from landfills and mine tails.

    Bocharnikova, E; Matichenkov, V; Jiang, J; Yuejin, C

    2017-07-01

    Monosilicic and polysilicic acids were shown to react with different types of the pollutants. The direction of these reactions can be managed by changing the monosilicic and polysilicic acid concentration in soil or water media. The objective of this study was to determine the effect of Si-treated calcium metallurgical slag and battery slag on the As, Se, Cd, Pb, Ni, Cr, and Hg mobility and bioavailability in mine tailings (Xikuangshan mine, Hunan, China). The results of column experiment showed that the Si-activated slags reduced leaching of As, Se, Cd, Pb, Ni, Cr, and Hg by 13-89% and transformed them into plant-unavailable forms. The greenhouse test has demonstrated that the Si-treated slags provided reinforced plant resistance to heavy metal toxicity and reduced pollutants in barley and pea leaves. Si-treated local solid slags could be used for creating the biogeochemical barriers on the pollutant streams from landfills or mine tailings sites.

  17. Reducing the Dietary Acid Load: How a More Alkaline Diet Benefits Patients With Chronic Kidney Disease.

    Passey, Caroline

    2017-05-01

    It has been proposed that a low-protein diet will slow progression of chronic kidney disease although studies have not always supported this belief. The accepted practice is that 60% to 70% of protein comes from high biological value (HBV) protein, but this limits patient choice and patients struggle to follow the diet. When a diet with only 30% HBV protein was trialed, there was a significant increase in serum bicarbonate, and patients preferred the diet. The dietary advice given in predialysis clinics was changed. HBV protein was restricted to approximately 50% of total protein, bread and cereal foods were allowed freely, and fruits and vegetables (F&V) were encouraged. Patients who followed the diet have seen a slowing of progression and occasionally regression of their renal function. Both observations and scientific literature indicate that this is because of a reduction in the acid content of the diet. When foods are metabolized, most proteins produce acid, and most F&V produce alkali. A typical 21 st -century diet produces 50 to 100 mEq H + per day which the kidney is challenged to excrete. Acid is excreted with phosphate and is limited to about 45 mEq H + per day. With chronic kidney disease, this falls progressively to below 20 mEq H + per day. Historically, ammonium excretion was believed to be excretion of acid (NH 3 +  + H + → NH 4 + ), but it is now understood to be a by-product in the neutralization of acid by glutamine. The remaining acid is neutralized or stored within the body. Bone and muscle are lost in order to neutralize the acid. Acid also accumulates within cells, and serum bicarbonate falls. The author postulates that reducing the acid load through a low-protein diet with greater use of vegetable proteins and increased F&V intake will slow progression or occasionally improve renal function while maintaining the nutritional status of the individual. Copyright © 2016 National Kidney Foundation, Inc. Published by Elsevier Inc. All

  18. Phenylboronic acid functionalized reduced graphene oxide based fluorescence nano sensor for glucose sensing

    Basiruddin, SK; Swain, Sarat K., E-mail: swainsk2@yahoo.co.in

    2016-01-01

    Reduced graphene has emerged as promising tools for detection based application of biomolecules as it has high surface area with strong fluorescence quenching property. We have used the concept of fluorescent quenching property of reduced graphene oxide to the fluorescent probes which are close vicinity of its surface. In present work, we have synthesized fluorescent based nano-sensor consist of phenylboronic acid functionalized reduced graphene oxide (rGO–PBA) and di-ol modified fluorescent probe for detection of biologically important glucose molecules. This fluorescent graphene based nano-probe has been characterized by high resolution transmission electron microscope (HRTEM), Atomic force microscope (AFM), UV–visible, Photo-luminescence (PL) and Fourier transformed infrared (FT-IR) spectroscopy. Finally, using this PBA functionalized reduced GO based nano-sensor, we were able to detect glucose molecule in the range of 2 mg/mL to 75 mg/mL in aqueous solution of pH 7.4. - Highlights: • Easy and simple synthesis of PBA functionalized reduced GO based nano probe. • PBA functionalized reduced GO graphene based nano-probes are characterized. • PBA functionalized reduced GO nano probe is used to detect glucose molecules. • It is very cost-effective and enzyme-free detection of glucose in solution.

  19. Selection of lixiviants for in situ uranium leaching. Information circular

    Tweeton, D.R.; Peterson, K.A.

    1981-10-01

    This Bureau of Mines publication provides information to assist in selecting a lixiviant (leach solution) for in situ uranium leaching. The cost, advantages, and disadvantages of lixiviants currently used and proposed are presented. Laboratory and field tests are described, and applications of geochemical models are discussed. Environmental, economic, and technical factors should all be considered. Satisfying environmental regulations on restoring groundwater quality is becoming an overriding factor, favoring sodium bicarbonate or dissolved carbon dioxide over ammonium carbonate. The cheapest lixiviant is dissolved carbon dioxide, but it is not effective in all deposits. Technical factors include clay swelling by sodium, acid consumption by calcite, and the low solubility of oxygen in shallow deposits

  20. The bile acid deoxycholate elicits defences in Arabidopsis and reduces bacterial infection.

    Zarattini, Marco; Launay, Alban; Farjad, Mahsa; Wénès, Estelle; Taconnat, Ludivine; Boutet, Stéphanie; Bernacchia, Giovanni; Fagard, Mathilde

    2017-05-01

    Disease has an effect on crop yields, causing significant losses. As the worldwide demand for agricultural products increases, there is a need to pursue the development of new methods to protect crops from disease. One mechanism of plant protection is through the activation of the plant immune system. By exogenous application, 'plant activator molecules' with elicitor properties can be used to activate the plant immune system. These defence-inducing molecules represent a powerful and often environmentally friendly tool to fight pathogens. We show that the secondary bile acid deoxycholic acid (DCA) induces defence in Arabidopsis and reduces the proliferation of two bacterial phytopathogens: Erwinia amylovora and Pseudomonas syringae pv. tomato. We describe the global defence response triggered by this new plant activator in Arabidopsis at the transcriptional level. Several induced genes were selected for further analysis by quantitative reverse transcription-polymerase chain reaction. We describe the kinetics of their induction and show that abiotic stress, such as moderate drought or nitrogen limitation, does not impede DCA induction of defence. Finally, we investigate the role in the activation of defence by this bile acid of the salicylic acid biosynthesis gene SID2, of the receptor-like kinase family genes WAK1-3 and of the NADPH oxidase-encoding RbohD gene. Altogether, we show that DCA constitutes a promising molecule for plant protection which can induce complementary lines of defence, such as callose deposition, reactive oxygen species accumulation and the jasmonic acid and salicylic acid signalling pathways. © 2016 BSPP AND JOHN WILEY & SONS LTD.

  1. Temporary reduction of radiation does not permanently reduce flavonoid glycosides and phenolic acids in red lettuce.

    Becker, Christine; Kläring, Hans-Peter; Kroh, Lothar W; Krumbein, Angelika

    2013-11-01

    Applying transparent daytime screens in greenhouses in cool seasons reduces the amount of energy needed for heating, but also the solar radiation available for crops. This can reduce yield and product quality of leafy vegetables because of constrained photosynthesis and altered biosynthesis. To study this, we cultivated five-week old red leaf lettuce (Lactuca sativa L.) for four weeks in growth chambers under a photosynthetic photon flux density (PPFD) of 225 and 410 μmol m(-2) s(-1), respectively. Some plants were exchanged between radiation intensities after two weeks. We investigated the concentration of five flavonoid glycosides, three caffeic acid derivatives, reducing sugars as well as plant growth. Remarkably, no significant influence of radiation intensity on the concentration of phenolic acids or anthocyanin glycosides was observed. In contrast, quercetin and luteolin glycoside concentration was between 14 and 34% lower in plants growing under lower compared to higher PPFD. Already after two weeks of cultivation, plants grown under lower PPFD contained less quercetin and luteolin glycosides but they completely compensated if subsequently transferred to higher PPFD until harvest. Hence, marketable lettuce heads which experienced temporary shading followed by an unshaded phase did not contain lower concentrations of flavonoid glycosides or phenolic acids. Also, there was no reduction of head mass in this variant. Our results suggest that saving energy in early growth stages is feasible without losses in yield or health promoting phenolic substances. In addition, there was a close correlation between the concentration of reducing sugars and some flavonoid glycosides, indicating a close metabolic connection between their biosynthesis and the availability of carbohydrates. Copyright © 2013 The Authors. Published by Elsevier Masson SAS.. All rights reserved.

  2. Leaching of a Cu-Co ore from Congo using sulphuric acidhydrogen peroxide leachants

    Seo S.Y.

    2013-01-01

    Full Text Available A Cu-Co ore from Katinga Province, the Republic of Congo containing 1.5% Co and 1.6% Cu was tested to determine the leachability of Cu and Co using sulphuric acid and hydrogen peroxide mixtures at different conditions. Without hydrogen peroxide, the maximum extraction of copper and cobalt were found to be ~80% and ~15%, respectively when the acid concentration was varied between 0.36 - 1.1M. When hydrogen peroxide was added (0.008-0.042M, Cu recovery was enhanced to ~90%. Recoveries of ~90% of Co could be achieved at 20ºC, using leachants consisting of 0.36M sulphuric acid and 0.025M hydrogen peroxide after 3 hours. The reaction time to reach 90% Co extraction was reduced to less than 2 hours at 30ºC. Stabcal modelling of the Eh-pH diagrams shows the importance of hydrogen peroxide as a reductant. The decrease of solution potential (300-350 mV by adding hydrogen peroxide was confirmed by Eh measurements during the tests. The leaching follows the shrinking core model kinetics, where the rate constant is linearly dependent on hydrogen peroxide concentration in the range 0-0.025M and proportional to (1/r2 where r is the average radius of the mineral particles. The activation energy for the leaching process is 72.3 kJ/mol.

  3. Bottle roll leach test for Temrezli uranium ore

    Çetin, K.; Bayrak, M.; Turan, A. İsbir; Üçgül, E.

    2014-01-01

    The bottle roll leach test is one of the dynamic leaching procedure which can meet in-situ mining needs for determining suitable working conditions and helps to simulate one of the important parameter; injection well design. In this test, the most important parameters are pulp density, acidic or basic concentration of leach solution, time and temperature. In recent years, bottle roll test is used not only for uranium but also gold, silver, copper and nickel metals where in situ leach (ISL) mining is going to be applied. For this purpose for gold and silver metal cyanide bottle roll tests and for uranium metal; acidic and basic bottle roll tests could be applied. The new leach test procedure which is held in General Directorate of Mineral Research and Exploration (MTA) of Turkey is mostly suitable for determining metal extraction conditions and recovery values in uranium containing ore bodies. The tests were conducted with samples taken from Temrezli Uranium Ore located in approximately 200 km east of Turkey’s capital, Ankara. Mining rights of Temrezli Ore is controlled 100% by Anatolia Energy Ltd. The resource estimate includes an indicated mineral resource of 10.827 Mlbs U_3O_8 [~4160 t U] at an average grade of 1426 ppm [~1210 ppm U] and an additional inferred resource of 6.587 Mlbs of U_3O_8 [~2530 t U] at an average grade of 904 ppm [~767 ppm U]. In accordance with the demand from Anatolia Energy bottle roll leach tests have been initiated in MTA laboratories to investigate the recovery values of low-grade uranium ore under in-situ leach conditions. Bottle roll leaching tests are performed on pulverized samples with representative lixiviant solution at ambient pressure and provide an initial evaluation of ore leachability with a rough estimate of recovery value. At the end of the tests by using 2 g/L NaHCO_3 and 0.2 g/L H_2O_2 more than 90% of uranium can pass into leach solution in 12 days. (author)

  4. An alginate-antacid formulation localizes to the acid pocket to reduce acid reflux in patients with gastroesophageal reflux disease

    Rohof, Wout O.; Bennink, Roel J.; Smout, Andre J. P. M.; Thomas, Edward; Boeckxstaens, Guy E.

    2013-01-01

    Alginate rafts (polysaccharide polymers that precipitate into a low-density viscous gel when they contact gastric acid) have been reported to form at the acid pocket, an unbuffered pool of acid that floats on top of ingested food and causes postprandial acid reflux. We studied the location of an

  5. Reduced gamma-aminobutyric acid concentration is associated with physical disability in progressive multiple sclerosis

    Solanky, Bhavana S.; Muhlert, Nils; Tur, Carmen; Edden, Richard A. E.; Wheeler-Kingshott, Claudia A. M.; Miller, David H.; Thompson, Alan J.; Ciccarelli, Olga

    2015-01-01

    Neurodegeneration is thought to be the major cause of ongoing, irreversible disability in progressive stages of multiple sclerosis. Gamma-aminobutyric acid is the principle inhibitory neurotransmitter in the brain. The aims of this study were to investigate if gamma-aminobutyric acid levels (i) are abnormal in patients with secondary progressive multiple sclerosis compared with healthy controls; and (ii) correlate with physical and cognitive performance in this patient population. Thirty patients with secondary progressive multiple sclerosis and 17 healthy control subjects underwent single-voxel MEGA-PRESS (MEscher-GArwood Point RESolved Spectroscopy) magnetic resonance spectroscopy at 3 T, to quantify gamma-aminobutyric acid levels in the prefrontal cortex, right hippocampus and left sensorimotor cortex. All subjects were assessed clinically and underwent a cognitive assessment. Multiple linear regression models were used to compare differences in gamma-aminobutyric acid concentrations between patients and controls adjusting for age, gender and tissue fractions within each spectroscopic voxel. Regression was used to examine the relationships between the cognitive function and physical disability scores specific for these regions with gamma-aminobuytric acid levels, adjusting for age, gender, and total N-acetyl-aspartate and glutamine-glutamate complex levels. When compared with controls, patients performed significantly worse on all motor and sensory tests, and were cognitively impaired in processing speed and verbal memory. Patients had significantly lower gamma-aminobutyric acid levels in the hippocampus (adjusted difference = −0.403 mM, 95% confidence intervals −0.792, −0.014, P = 0.043) and sensorimotor cortex (adjusted difference = −0.385 mM, 95% confidence intervals −0.667, −0.104, P = 0.009) compared with controls. In patients, reduced motor function in the right upper and lower limb was associated with lower gamma-aminobutyric acid

  6. Pharmacokinetics of reduced iso-α-acids in volunteers following clear bottled beer consumption.

    Rodda, Luke N; Gerostamoulos, Dimitri; Drummer, Olaf H

    2015-05-01

    Reduced iso-α-acids (reduced IAA) consisting of the rho-, tetrahydro- and hexahydro-IAA groups (RIAA, TIAA and HIAA, respectively) are ingredient congeners specific to beer and generally found in clear and also occasionally green bottled beer. Concentrations of reduced IAA were determined in the blood and urine of five volunteers over 6h following the consumption of small volumes of beer containing each of the reduced IAA. The reduced IAA were absorbed and bioavailable with peak concentrations at 0.5h followed by a drop of generally fivefold by 2h. Preliminary pharmacokinetics of these compounds in humans shows relatively small inter-individual differences and an estimated short half-life varying between ∼38 and 46min for the three groups. Comparison of RIAA analyte ratios within the group indicate that some analytes eliminate relatively faster than others and the formation of metabolite products was observed. Preliminary urine analysis showed only unmodified RIAA analytes were detectable throughout 6h and suggests extensive phase I metabolism of TIAA and HIAA analytes. In authentic forensic casework where clear or green bottled beers are consumed, the identification of reduced IAA groups may provide a novel method to target ingredient congeners consistent with beer ingestion and suggest the type of beer consumed. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

  7. Friction reducing behavior of stearic acid film on a textured aluminum substrate

    Zhang, Quan [School of Mechanical Engineering, Qingdao Technological University, Qingdao 266033 (China); Wan, Yong, E-mail: wanyong@qtech.edu.cn [School of Mechanical Engineering, Qingdao Technological University, Qingdao 266033 (China); Li, Yang; Yang, Shuyan [School of Mechanical Engineering, Qingdao Technological University, Qingdao 266033 (China); Yao, Wenqing [Analysis Center of Tsinghua University, Beijing 100084 (China)

    2013-09-01

    A simple two-step process was developed to render the aluminum hydrophobicity with lower friction. The textured aluminum substrate was firstly fabricated by immersed in a sodium hydroxide solution at 100 °C for 1 h. Stearic acid film was then deposited to acquire high hydrophobicity. Scanning electron microscopy, IR spectroscopy and water contact angle measurements were used to analyze the morphological features, chemical structure and hydrophobicity of prepared samples, respectively. Moreover, the friction reducing behavior of the organic–inorganic composite film on aluminum sliding against steel was evaluated in a ball-on-plate configuration. It was found that the stearic acid film on the textured aluminum led to decreased friction with significantly extended life.

  8. Effect of Amine Adlayer on Electrochemical Uric Acid Sensor Conducted on Electrochemically Reduced Graphene Oxide

    Park, Sumi; Kim, Kyuwon [Incheon National University, Incheon (Korea, Republic of)

    2016-03-15

    The electrochemical biosensing efficiency of uric acid (UA) detection on an electrochemically reduced graphene oxide (ERGO)-decorated electrode surface was studied by using various amine linkers used to immobilize ERGO. The amine linkers aminoethylphenyldiazonium , 2,2'-(ethylenedioxy)bis(ethylamine), 3-aminopro-pyltriethoxysilane, and polyethyleneimine were coated on indium-tin-oxide electrode surfaces through chemical or electrochemical deposition methods. ERGO-decorated surfaces were prepared by the electrochemical reduction of graphene oxide (GO), which was immobilized on the amine-coated electrode surfaces through the electrostatic interaction between GO and the ammonium ion of the linker on the surface. We monitored the sensing results of electrochemical UA detection with differential pulse voltammetry. The ERGO-modified surface presented electrocatalytic oxidation of UA and ascorbic acid. Among the different amines tested, 3-aminopropyltriethoxysilane provided the best biosensing performance in terms of sensitivity and reproducibility.

  9. Effect of Amine Adlayer on Electrochemical Uric Acid Sensor Conducted on Electrochemically Reduced Graphene Oxide

    Park, Sumi; Kim, Kyuwon

    2016-01-01

    The electrochemical biosensing efficiency of uric acid (UA) detection on an electrochemically reduced graphene oxide (ERGO)-decorated electrode surface was studied by using various amine linkers used to immobilize ERGO. The amine linkers aminoethylphenyldiazonium , 2,2'-(ethylenedioxy)bis(ethylamine), 3-aminopro-pyltriethoxysilane, and polyethyleneimine were coated on indium-tin-oxide electrode surfaces through chemical or electrochemical deposition methods. ERGO-decorated surfaces were prepared by the electrochemical reduction of graphene oxide (GO), which was immobilized on the amine-coated electrode surfaces through the electrostatic interaction between GO and the ammonium ion of the linker on the surface. We monitored the sensing results of electrochemical UA detection with differential pulse voltammetry. The ERGO-modified surface presented electrocatalytic oxidation of UA and ascorbic acid. Among the different amines tested, 3-aminopropyltriethoxysilane provided the best biosensing performance in terms of sensitivity and reproducibility.

  10. Heavy Metal Leaching as Affected by Long-Time Organic Waste Fertilizer Application.

    Lekfeldt, Jonas Duus Stevens; Holm, Peter E; Kjærgaard, Charlotte; Magid, Jakob

    2017-07-01

    The recycling of urban waste products as fertilizers in agriculture may introduce contaminants such as heavy metals into soil that may leach and contaminate groundwater. In the present study, we investigated the leaching of heavy metals from intact soil cores collected in the long-term agricultural field trial CRUCIAL. At the time of sampling, the equivalent of >100 yr of urban waste fertilizers following Danish legislation had been applied. The leaching of Cu was significantly increased in the treatments receiving organic waste products compared with the unfertilized control but remained below the permissible level following Danish drinking water guidelines. The leaching of Cu was controlled primarily by the topsoil Cu content and by the leaching of dissolved organic carbon (DOC) but at the same time significantly correlated with leaching of colloids in soils that had not received fertilizer or had received an organic fertilizer with a low concentration of Cu. The leaching of Zn, Cd, and Co was not significantly increased in urban waste-fertilized treatments. The leaching of Mo was elevated in accelerated waste treatments (both agricultural and urban), and the leaching of Mo was linked to the leaching of DOC. Since leaching of Cr and Pb was strongly linked to the level of colloid leaching, leaching of these metals was reduced in the urban waste treatments. Overall, the results presented should not raise concern regarding the agricultural use of urban waste products in agriculture as long as the relevant guidelines are followed. Copyright © by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America, Inc.

  11. Sulfate-reducing bacteria mediate thionation of diphenylarsinic acid under anaerobic conditions.

    Guan, Ling; Shiiya, Ayaka; Hisatomi, Shihoko; Fujii, Kunihiko; Nonaka, Masanori; Harada, Naoki

    2015-02-01

    Diphenylarsinic acid (DPAA) is often found as a toxic intermediate metabolite of diphenylchloroarsine or diphenylcyanoarsine that were produced as chemical warfare agents and were buried in soil after the World Wars. In our previous study Guan et al. (J Hazard Mater 241-242:355-362, 2012), after application of sulfate and carbon sources, anaerobic transformation of DPAA in soil was enhanced with the production of diphenylthioarsinic acid (DPTAA) as a main metabolite. This study aimed to isolate and characterize anaerobic soil microorganisms responsible for the metabolism of DPAA. First, we obtained four microbial consortia capable of transforming DPAA to DPTAA at a high transformation rate of more than 80% after 4 weeks of incubation. Sequencing for the bacterial 16S rRNA gene clone libraries constructed from the consortia revealed that all the positive consortia contained Desulfotomaculum acetoxidans species. In contrast, the absence of dissimilatory sulfite reductase gene (dsrAB) which is unique to sulfate-reducing bacteria was confirmed in the negative consortia showing no DPAA reduction. Finally, strain DEA14 showing transformation of DPAA to DPTAA was isolated from one of the positive consortia. The isolate was assigned to D. acetoxidans based on the partial 16S rDNA sequence analysis. Thionation of DPAA was also carried out in a pure culture of a known sulfate-reducing bacterial strain, Desulfovibrio aerotolerans JCM 12613(T). These facts indicate that sulfate-reducing bacteria are microorganisms responsible for the transformation of DPAA to DPTAA under anaerobic conditions.

  12. Reducing Renal Uptake of {sup 177}Lu Labeled CCK Derivative using Basic Amino Acids

    Lee, Soyoung; Lim, Jaecheong; Joh, Eunha [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2014-05-15

    Radiolabeled peptides have been designed to target the relative receptors overespressed in tumor cells, such as integrin αvβ3, gastrin-releasing peptide receptor (GRPR), melanocortin-1 receptor (MC1-R), glucagon-like peptide-a receptor (GLP-1R), and cholecystokinin (CCK) receptor. Most of these peptides are eliminated from the body via the kidney and are partly reabsorbed in the proximal tubular cells. However, the high renal uptake of the radiolabeled peptides may lead to renal toxicity. In this study we investigated various amino acid solutions to reduce the renal uptake of {sup 177}Lu-DOTA-CCK derivative. Renal uptake of {sup 177}Lu-DOTA-CCK derivative is effectively reduced by the administration of positively charged amino acids. The administration of 12 mg of L-lysine was as effective in reducing the renal uptake as 6 mg of lysine and 6 mg of arginine combinations. Further studies will be performed to identify the most potent inhibitor of renal reuptake of radiolabeled peptides and minimize the chance of unwanted side effects.

  13. 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.

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

    Mahdy, M.A.; EL-Hazek, M.N.

    1998-01-01

    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

  15. Boric acid reduces axonal and myelin damage in experimental sciatic nerve injury

    Zahir Kizilay

    2016-01-01

    Full Text Available The aim of this study was to investigate the effects of boric acid in experimental acute sciatic nerve injury. Twenty-eight adult male rats were randomly divided into four equal groups (n = 7: control (C, boric acid (BA, sciatic nerve injury (I , and sciatic nerve injury + boric acid treatment (BAI. Sciatic nerve injury was generated using a Yasargil aneurysm clip in the groups I and BAI. Boric acid was given four times at 100 mg/kg to rats in the groups BA and BAI after injury (by gavage at 0, 24, 48 and 72 hours but no injury was made in the group BA. In vivo electrophysiological tests were performed at the end of the day 4 and sciatic nerve tissue samples were taken for histopathological examination. The amplitude of compound action potential, the nerve conduction velocity and the number of axons were significantly lower and the myelin structure was found to be broken in group I compared with those in groups C and BA. However, the amplitude of the compound action potential, the nerve conduction velocity and the number of axons were significantly greater in group BAI than in group I. Moreover, myelin injury was significantly milder and the intensity of nuclear factor kappa B immunostaining was significantly weaker in group BAI than in group I. The results of this study show that administration of boric acid at 100 mg/kg after sciatic nerve injury in rats markedly reduces myelin and axonal injury and improves the electrophysiological function of injured sciatic nerve possibly through alleviating oxidative stress reactions.

  16. Partitioning of elements during coal combustion and leaching experiments

    Wang Wen-feng; Qin Yong; Song Dang-yu; Wang Jun-yi [China University of Mining & Technology, Xuzhou (China). School of Resources and Earth Science

    2009-04-15

    The mineral component and content of sulfur and 42 major and trace elements of the feed coal, fly and bottom ashes collected from Shizuishan coal-fired power plant, Ningxia, China were analyzed using AFS, INAA, ICP-MS, ICP-AES, XRD. Based on the coal combustion and leaching experiments, the partitioning of these elements during coal combustion and the leaching behavior of the 11 potentially hazardous elements, including As, Cd, Co, Cr, Hg, Mo, Ni, Pb, Se, Th and U were investigated. The results show that the distribution of elements in the fly and bottom ashes is controlled by their volatilities and modes of occurrence in the coal. The degree of volatilization of elements may be mainly associated with boiling/melting points of these elements and their compounds. The elements easily volatilized, organically bound or associated with sub-micrometer and nano minerals (e.g. Al and Na) tend to be enriched in the fine fractions of fly ash, and most elements do not vaporize which are approximately equally partitioned in the fly and bottom ashes. The emission rates of As, Cr, K, Mg, Mn, Mo, Pb, Sb, and Zn are notably influenced by the temperature ranging from 877 to 1300{sup o}C. The leaching behavior of elements depend significantly on their geochemical properties and modes of occurrence. The elements with a low degree of volatilization are not easily leached, while volatile elements easily leached under the acid conditions. Arsenic, B Br, Cd, Cu, Hg, Pb, S, Sb and Se show a higher emission rate during coal combustion, and the leached concentrations of Cd, Co, Mo, Ni and U in the acid media exceed their limited concentrations recommended in relevant environment quality standards for water, which will harm the environment. 32 refs., 4 figs., 4 tabs.

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

    Ngantung, Billy; Agustin, Riska; Ravi'i

    2017-01-01

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

  18. NEXT GENERATION LEACHING TESTS FOR EVALUATING LEACHING OF INORGANIC CONSTITUENTS

    In the U.S. as in other countries, there is increased interest in using industrial by-products as alternative or secondary materials, helping to conserve virgin or raw materials. The LEAF and associated test methods are being used to develop the source term for leaching or any i...

  19. Lithium-storage Properties of Gallic Acid-Reduced Graphene Oxide and Silicon-Graphene Composites

    Xu, Binghui; Zhang, Jintao; Gu, Yi; Zhang, Zhi; Al Abdulla, Wael; Kumar, Nanjundan Ashok; Zhao, X.S.

    2016-01-01

    Graphene oxide (GO) was de-oxygenated using gallic acid under mild conditions to prepare reduced graphene oxide (RGO). The resultant RGO showed a lithium-ion storage capacity of 1280 mA h g −1 at a current density of 200 mA g −1 after 350 cycles when used as an anode for lithium ion batteries. The RGO was further used to stabilize silicon (Si) nanoparticles to prepare silicon-graphene composite electrode materials. Experimental results showed that a composite electrode prepared with a mass ratio of Si:GO = 1:2 exhibited the best lithium ion storage performance.

  20. Efficacy of tranexamic acid in reducing allogeneic blood products in adolescent idiopathic scoliosis surgery.

    Sui, Wen-yuan; Ye, Fang; Yang, Jun-lin

    2016-04-27

    Adolescent idiopathic scoliosis (AIS) surgery usually require prolonged operative times with extensive soft tissue dissection and significant perioperative blood loss, and allogeneic blood products are frequently needed. Methods to reduce the requirement for transfusion would have a beneficial effect on these patients. Although many previous studies have revealed the efficacy of tranexamic acid (TXA) in spinal surgery, there is still a lack of agreement concerning the reduction of both blood loss and transfusion requirements of large dose tranexamic acid (TXA) in surgery for adolescent idiopathic scoliosis (AIS). The objective of this study was to elevate the efficacy and safety of a large dose tranexamic acid (TXA) in reducing transfusion requirements of allogeneic blood products in adolescent idiopathic scoliosis (AIS) surgery using a retrospective study designed with historical control group. One hundred thirty seven consecutive AIS patients who underwent surgery treatment with posterior spinal pedicle systems from August 2011 to March 2015 in our scoliosis center were retrospectively reviewed. Patients were divided into two groups, the TXA group and the historical recruited no TXA group (NTXA). Preoperative demographics, radiographic parameters, operative parameters, estimated blood loss (EBL), total irrigation fluid, number of patients requiring blood transfusion, mean drop of Hb (Pre-op Hb-Post-op Hb), haematocrit pre and post-surgery, mean volume of blood transfusion, hospitalization time, and adverse effect were recorded and compared. All the patients were successfully treated with satisfied clinical and radiographic outcomes. There were 71 patients in the TXA group and 66 patients in the NTXA group. The preoperative demographics were homogeneity between two groups (P > 0.05). There were no significant difference in average operative time between two groups (209 min vs 215 min, p >0.05). Number of patients in the TXA group showed a significant decrease in