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

Science.gov (United States)

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.

Acid leaching of mixed spent Li-ion batteries

Directory of Open Access Journals (Sweden)

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.

Leaching of gold, silver and accompanying metals from circuit boards (PCBs waste

Directory of Open Access Journals (Sweden)

Jana Ficeriová

2011-12-01

Full Text Available Au-Ag noble metal wastes represent a wide range of waste types and forms, with various accompanying metallic elements.The presented leaching strategy for Au-Ag contained in circuit boards (PCBs aims at gaining gold and silver in the metallic form.Application of the proposed ammonium thiosulphate leaching process for the treatment of the above mentioned Au-Ag containing wastesrepresents a practical, economic and at the same time an ecological solution. The ammonium thiosulphate based leaching of gold and silverfrom PCBs waste, using crushing as a pretreatment, was investigated. It was possible to achieve 98 % gold and 93 % silver recovery within48 hours of ammonium thiosulphate leaching. This type of leaching is a better leaching procedure for recovery of gold and silver from PCBwaste than the classical toxic cyanide leaching. 84 % Cu, 82 % Fe, 77 % Al, 76 % Zn, 70 % Ni, 90 % Pd, 88 % Pb and 83 % Sn recovery ofthe accompanying metals was achieved, using sulphuric acid with hydrogen peroxide, sodium chloride and aqua regia. A four steps leachingprocess gave a very satisfactory yield and a more rapid kinetics for all observed metals solubilization than other technologies.

Heavy metal recovery from contaminated biomass ashes by chemical leaching, bioleaching and biosorption

International Nuclear Information System (INIS)

Pirker, K.

2000-01-01

Ashes from biomass combustion plants contain plant nutrients which makes their application as fertilizers economically interesting. The possibility of recycling the ash can be looked upon as a contribution to obtain a sustainable energy utilization from biomass. The ash contains heavy metals which have to be removed. The possibility of decontaminating the ash by chemical and biological leaching was investigated. The leaching capacity of commercially available organic and inorganic acids and of citric acid produced by the fungus Penicillium simplicissimus were determined. A process for heavy metal recovery from biomass ashes consisting of four steps was designed. All environmentally relevant heavy metals (except lead) were removed from contaminated biomass ashes by chemical leaching. The heavy metals were recovered and enriched by precipitation and subsequent biosorption. Inactivated bacteria and fungi were used as biosorbents. The overall costs and the washing-out of plant nutrients from the ashes by chemical leaching were drawbacks of the metal recovering process. Biosorption in combination with existing processes of waste water treatment would offer another promising possibility for achieving the low Austrian limiting values for heavy metals in waste water. (author)

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

Science.gov (United States)

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.

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

Science.gov (United States)

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.

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

Science.gov (United States)

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

2016-04-01

Low-molecular-mass organic acids (LMMOA) are of key importance for mobilisation and fate of metals in soil, by functioning as ligands that increase the amount of dissolved metal in solution or by dissociation of metal binding minerals. Column leaching experiments were performed on soil polluted with As and Pb, in order to determine the specificity of LMMOA related release for individual elements, at varying organic acid concentrations. Acetic, citric and oxalic acids were applied in 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.

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

Science.gov (United States)

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.

Acid pre-treatment method for in situ ore leaching

International Nuclear Information System (INIS)

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

Comparative studies on acid leaching of zinc waste materials

Science.gov (United States)

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.

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

Science.gov (United States)

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%.

Leaching of Electronic Waste Using Biometabolised Acids

Institute of Scientific and Technical Information of China (English)

M. Saidan; B. Brown; M. Valix

2012-01-01

The revolution in information and communication technology has brought huge technical benefits and wealth, but has created a major global problem： the generation of vast amounts of electronic waste, or e-waste through product obsolesce. The challenge in managing e-waste will be in developing sustainable recycling tech- nologies that are able to address the volume and complexity of this waste using cost effective and ecologically sen-sitive methods. In this study, the capability or microorganism metabolic acids in dissolving the metallic tractions from waste printed circuit boards was examined. Several factors were considered in the examination of the activityof the acids-including secondary reactions, solution pH, temperature and the nature of ligands in solutions （or bioacid constituents）. The leaching tests were cgnducted ex-situ, using synthetic organic acids. Leaching was performed for periods of up to 6 hat 70-90 ℃ and 1000 r-min-1.

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

Science.gov (United States)

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.

Characterization of dross and its recovery by sulphuric acid leaching

Science.gov (United States)

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.

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

Science.gov (United States)

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

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

Science.gov (United States)

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.

Organic reductants based leaching: A sustainable process for the recovery of valuable metals from spent lithium ion batteries.

Science.gov (United States)

Chen, Xiangping; Guo, Chunxiu; Ma, Hongrui; Li, Jiazhu; Zhou, Tao; Cao, Ling; Kang, Duozhi

2018-05-01

It is significant to recover metal values from spent lithium ion batteries (LIBs) for the alleviation or prevention of potential risks towards environmental pollution and public health, as well as for the conservation of valuable metals. Herein a hydrometallurgical process was proposed to explore the possibility for the leaching of different metals from waste cathodic materials (LiCoO 2 ) of spent LIBs using organics as reductant in sulfuric acid medium. According to the leaching results, about 98% Co and 96% Li can be leached under the optimal experimental conditions of reaction temperature - 95 °C, reaction time - 120 min, reductive agent dosage - 0.4 g/g, slurry density - 25 g/L, concentration of sulfuric acid-3 mol/L in H 2 SO 4  + glucose leaching system. Similar results (96% Co and 100% Li) can be obtained in H 2 SO 4  + sucrose leaching system under optimized leaching conditions. Despite a complete leaching of Li (∼100%), only 54% Co can be dissolved in the H 2 SO 4  + cellulose leaching system under optimized leaching conditions. Finally, different characterization methods, including UV-Vis, FT-IR, SEM and XRD, were employed for the tentative exploration of reductive leaching reactions using organic as reductant in sulfuric acid medium. All the leaching and characterization results confirm that both glucose and sucrose are effective reductants during leaching, while cellulose should be further degraded to organics with low molecular weights to achieve a satisfactory leaching performance. Copyright © 2018 Elsevier Ltd. All rights reserved.

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

Science.gov (United States)

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

2015-04-01

Environmentally hazardous substances contained in spent Li-ion batteries, such as heavy metals and nocuous organics, will pose a threat to the environment and human health. On the other hand, the sustainable recycling of spent lithium-ion batteries may bring about environmental and economic benefits. In this study, a hydrometallurgical process was adopted for the comprehensive recovery of nickel, manganese, cobalt and lithium from sulfuric acid leaching liquor from waste cathode materials of spent lithium-ion batteries. First, nickel ions were selectively precipitated and recovered using dimethylglyoxime reagent. Recycled dimethylglyoxime could be re-used as precipitant for nickel and revealed similar precipitation performance compared with fresh dimethylglyoxime. Then the separation of manganese and cobalt was conducted by solvent extraction method using cobalt loaded D2EHPA. And McCabe-Thiele isotherm was employed for the prediction of the degree of separation and the number of extraction stages needed at specific experimental conditions. Finally, cobalt and lithium were sequentially precipitated and recovered as CoC2O4 ⋅ 2H2O and Li2CO3 using ammonium oxalate solution and saturated sodium carbonate solution, respectively. Recovery efficiencies could be attained as follows: 98.7% for Ni; 97.1% for Mn, 98.2% for Co and 81.0% for Li under optimized experimental conditions. This hydrometallurgical process may promise a candidate for the effective separation and recovery of metal values from the sulfuric acid leaching liquor. Copyright © 2015 Elsevier Ltd. All rights reserved.

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

International Nuclear Information System (INIS)

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

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

Science.gov (United States)

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

2009-10-15

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

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

International Nuclear Information System (INIS)

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)

Rejuvenation of residual oil hydrotreating catalysts by leaching of foulant metals. Modelling of the metal leaching process

Energy Technology Data Exchange (ETDEWEB)

Marafi, M.; Kam, E.K.T.; Stanislaus, A.; Absi-Halabi, M. [Petroleum Technology Department, Petroleum, Petrochemicals and Materials Division, Kuwait Institute for Scientific Research, Safat (Kuwait)

1996-11-19

Increasing emphasis has been paid in recent years on the development of processes for the rejuvenation of spent residual oil hydroprocessing catalysts, which are deactivated by deposition of metals (e.g. vanadium) and coke. As part of a research program on this subject, we have investigated selective removal of the major metal foulant from the spent catalyst by chemical leaching. In the present paper, we report the development of a model for foulant metals leaching from the spent catalyst. The leaching process is considered to involve two consecutive operations: (1) removal of metal foulants along the main mass transfer channels connected to the narrow pores until the pore structure begins to develop and (2) removal of metal foulants from the pore structure. Both kinetic and mass transfer aspects were considered in the model development, and a good agreement was noticed between experimental and simulated results

Biological leaching of heavy metals from a contaminated soil by Aspergillus niger

International Nuclear Information System (INIS)

Ren Wanxia; Li Peijun; Geng Yong; Li Xiaojun

2009-01-01

Bioleaching of heavy metals from a contaminated soil in an industrial area using metabolites, mainly weak organic acids, produced by a fungus Aspergillus niger was investigated. Batch experiments were performed to compare the leaching efficiencies of one-step and two-step processes and to determine the transformation of heavy metal chemical forms during the bioleaching process. After the one or two-step processes, the metal removals were compared using analysis of variance (ANOVA) and least-significance difference (LSD). A. niger exhibits a good potential in generating a variety of organic acids effective for metal solubilisation. Results showed that after the one-step process, maximum removals of 56%, 100%, 30% and 19% were achieved for copper, cadmium, lead and zinc, respectively. After the two-step process, highest removals of 97.5% Cu, 88.2% Cd, 26% Pb, and 14.5% Zn were obtained. Results of sequential extraction showed that organic acids produced by A. niger were effective in removing the exchangeable, carbonate, and Fe/Mn oxide fractions of Cu, Cd, Pb and Zn; and after both processes the metals remaining in the soil were mainly bound in stable fractions. Such a treatment procedure indicated that leaching of heavy metals from contaminated soil using A. niger has the potential for use in remediation of contaminated soils.

Biological leaching of heavy metals from a contaminated soil by Aspergillus niger

Energy Technology Data Exchange (ETDEWEB)

Ren Wanxia, E-mail: ren_laura@163.com [Institute of Applied Ecology, Chinese Academy of Sciences, 72 Wenhua Road, Shenyang 110016 (China); Li Peijun, E-mail: lipeijun@iae.ac.cn [Institute of Applied Ecology, Chinese Academy of Sciences, 72 Wenhua Road, Shenyang 110016 (China); Geng Yong; Li Xiaojun [Institute of Applied Ecology, Chinese Academy of Sciences, 72 Wenhua Road, Shenyang 110016 (China)

2009-08-15

Bioleaching of heavy metals from a contaminated soil in an industrial area using metabolites, mainly weak organic acids, produced by a fungus Aspergillus niger was investigated. Batch experiments were performed to compare the leaching efficiencies of one-step and two-step processes and to determine the transformation of heavy metal chemical forms during the bioleaching process. After the one or two-step processes, the metal removals were compared using analysis of variance (ANOVA) and least-significance difference (LSD). A. niger exhibits a good potential in generating a variety of organic acids effective for metal solubilisation. Results showed that after the one-step process, maximum removals of 56%, 100%, 30% and 19% were achieved for copper, cadmium, lead and zinc, respectively. After the two-step process, highest removals of 97.5% Cu, 88.2% Cd, 26% Pb, and 14.5% Zn were obtained. Results of sequential extraction showed that organic acids produced by A. niger were effective in removing the exchangeable, carbonate, and Fe/Mn oxide fractions of Cu, Cd, Pb and Zn; and after both processes the metals remaining in the soil were mainly bound in stable fractions. Such a treatment procedure indicated that leaching of heavy metals from contaminated soil using A. niger has the potential for use in remediation of contaminated soils.

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

Science.gov (United States)

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

2015-07-01

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

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

International Nuclear Information System (INIS)

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

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

Energy Technology Data Exchange (ETDEWEB)

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

2015-04-15

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

Extraction of metals from ores by bacterial leaching: present status and future prospects

International Nuclear Information System (INIS)

Kelly, D.P.

1977-01-01

The principal organism effecting bacterial leaching of ferrous and sulfide ores is Thiobacillus ferrooxidans, though other thiobacilli and other bacteria may be involved. The process depends on (a) direct solubilization of metal sulfides by bacterial oxidation; (b) dissolution of metal sulfides or oxides by ferric iron produced by bacterial pyrite oxidation. Mining spoil dumps and low grade ores can be leached for copper or uranium by cheap low-level technology. Dump leaching enables maximum recovery of valuable metal from any ore, but makes possible exploitation of very low grade Cu and U ores. Continuous extraction processes are possible where a continuously growing bacterial culture is fed with pyritic ores (or FeSO 4 or other sulfide) and continuous metal solubilization proceeds. Intimate contact between the bacteria and the ore to be leached (especially with uranium oxide ores) is not always necessary: leaching of UO 2 ores probably depends only on ferric iron reaction with the ore. Degradation of pyrite-containing rocks may also be developed as part of future recovery processes for petroleum from oil shales. Two-stage leaching systems present the best prospect for developing a higher-level technology for metal extraction. State 1: bacterial generation of Fe 3+ from pyrite or a Fe 2+ source; Stage 2: chemical leaching of ore by Fe 3+ in acid solution. Two-stage processes can be surface processes using crushed or milled ores or can be applied to underground solution mining, when an ore (e.g. uranium) can be leached by pumping Fe 3+ solutions through shattered underground deposits, metal recovered (e.g. solvent extraction) and Fe 3+ regenerated by bacterial oxidation at the surface. The use of controlled continuous microbial cultures to generate either bacteria or ferric iron is outlined

Leaching of heavy metals from timah langat amang

International Nuclear Information System (INIS)

Shukri bin Othman

1990-01-01

Accelerated leaching studies of amang from Timah Langat for heavy metals showed that the material was rather stable. From almost 24 types of heavy metals contained in the material, the metal that leached out most was Al, followed by Pb, U, Cu, Mn, Fe, Mg, Y and La but at smaller quantities. The studies also showed that amang was very porous. The high seepage rate resulted in the solubilities of the metals not reaching equilibrium. In that situation, the leaching of heavy metals from amang was dependent on the seepage rate of water, the height of the material, the volume of water that seeped through and the solubility of the metals

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

Science.gov (United States)

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.

Leaching of heavy metals from steelmaking slags

International Nuclear Information System (INIS)

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

2006-01-01

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

High level leaching of heavy metals from colorful ceramic foodwares: a potential risk to human.

Science.gov (United States)

Aderemi, Taiwo Adedoyin; Adenuga, Adeniyi Abiodun; Oyekunle, John Adekunle Oyedele; Ogunfowokan, Aderemi Okunola

2017-07-01

Ceramic foodwares are among the products used by people on daily basis without being cautious of exposures to heavy metals through possible leaching from the glaze ceramics. This study investigated the levels of heavy metals found in some commonly used ceramic foodwares in Nigeria with the aim of determining levels of human exposures through the use of the ceramics. To achieve this, acid digestion was carried out for the total metal concentrations and leaching tests were done using 4% acetic acid as a leaching agent. Metal concentrations were quantified using flame atomic absorption spectrometry (FAAS) and particle-induced X-ray emission spectrometry (PIXES) analysis. All the ceramic foodwares studied were found to contain varied amounts of heavy metals in their glazes, with concentrations in the range of 26.45-2071.46, 5.20-547.00, 1.24-2681.02, 2590.00-8848.40, 6.42-654.66, 112.69-649.95, 63.38-2518.51, and 3786.51-8249.44 μg g -1 for Pb, Cd, Zn, As, Cu, Cr, Mn, and Fe, respectively. Concentrations of the metals leached from the ceramics were in the range of 0.11-0.97, 0.01-0.28, 0.00-4.19, 1.93-15.00, 0.01-0.41, 0.09-0.60, 0.01-2.14, and 0.01-11.53 mgL -1 for Pb, Cd, Zn, As, Cu, Cr, Mn, and Fe, respectively. Comparing the ratio of the metals leached from the ceramic wares with those of the metal oxides in the ceramics, it was noticeable that not all the metals detected in the ceramic samples were domiciled in the glaze but in the clay materials used for the ceramics.

Leaching Properties of Naturally Occurring Heavy Metals from Soils

Science.gov (United States)

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

2014-12-01

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

Suppressing Heavy Metal Leaching through Ball Milling of Fly Ash

Directory of Open Access Journals (Sweden)

Zhiliang Chen

2016-07-01

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

Heavy metal uptake and leaching from polluted soil using permeable barrier in DTPA-assisted phytoextraction.

Science.gov (United States)

Zhao, Shulan; Shen, Zhiping; Duo, Lian

2015-04-01

Application of sewage sludge (SS) in agriculture is an alternative technique of disposing this waste. But unreasonable application of SS leads to excessive accumulation of heavy metals in soils. A column experiment was conducted to test the availability of heavy metals to Lolium perenne grown in SS-treated soils following diethylene triamine penta acetic acid (DTPA) application at rates of 0, 10 and 20 mmol kg(-1) soil. In order to prevent metal leaching in DTPA-assisted phytoextraction process, a horizontal permeable barrier was placed below the treated soil, and its effectiveness was also assessed. Results showed that DTPA addition significantly increased metal uptake by L. perenne shoots and metal leaching. Permeable barriers increased metal concentrations in plant shoots and effectively decreased metal leaching from the treated soil. Heavy metals in SS-treated soils could be gradually removed by harvesting L. perenne many times in 1 year and adding low dosage of DTPA days before each harvest.

Simplified process for leaching precious metals from fuel cell membrane electrode assemblies

Science.gov (United States)

Shore, Lawrence [Edison, NJ; Matlin, Ramail [Berkeley Heights, NJ

2009-12-22

The membrane electrode assemblies of fuel cells are recycled to recover the catalyst precious metals from the assemblies. The assemblies are cryogenically embrittled and pulverized to form a powder. The pulverized assemblies are then mixed with a surfactant to form a paste which is contacted with an acid solution to leach precious metals from the pulverized membranes.

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

OpenAIRE

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 ...

The determination, by x-ray-fluorescence spectrometry, of noble and base metals in matte-leach residues

International Nuclear Information System (INIS)

Austen, C.E.

1977-01-01

An accurate and precise method is described for the determination of noble and base metals in matte-leach residues. Preparation of the samples essentially involves fusion with sodium peroxide in a zirconium crucible and leaching with hydrochloric and nitric acids. Matrix correction and calibration are achieved by use of the single-standard calibration method with reference solutions prepared from pure metals or from compounds of the element to be determined

Leaching of metals from soil contaminated by mining activities.

Science.gov (United States)

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.

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

International Nuclear Information System (INIS)

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.

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

Science.gov (United States)

Gutknecht, Toni; Gustafsson, Anna; Forsgren, Christer; 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

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

Directory of Open Access Journals (Sweden)

Toni Gutknecht

2015-01-01

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

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

Science.gov (United States)

Gwenzi, Willis; Mupatsi, Nyarai M

2016-03-01

Application of coal ash in construction materials is constrained by the potential risk of heavy metal leaching. Limited information is available on the comparative heavy metal leaching from coal ash-versus conventional concrete. The current study compared total and leached heavy metal concentrations in unbound coal ash, cement and sand; and investigated the effect of initial leachant pH on heavy metal leaching from coal-ash versus conventional concrete monoliths and their debris. Total Pb, Mn and Zn in coal ash were lower than or similar to that of other materials, while Cu and Fe showed the opposite trend. Leached concentrations of Zn, Pb, Mn, Cu and Fe in unbound coal ash, its concrete and debris were comparable and in some cases even lower than that for conventional concrete. In all cases, leached concentrations accounted for just leaching data showed that leaching was dominated by diffusion. Overall, the risk of Zn, Pb, Mn, Cu and Fe leaching from coal ash and its concrete was minimal and comparable to that of conventional concrete, a finding in contrast to widely held public perceptions and earlier results reported in other regions such as India. In the current study the coal ash, and its concrete and debris had highly alkaline pH indicative of high acid neutralizing and pH buffering capacity, which account for the stabilization of Zn, Pb, Mn, Cu and Fe. Based on the low risk of Zn, Pb, Mn, Cu and Fe leaching from the coal ash imply that such coal ash can be incorporated in construction materials such as concrete without adverse impacts on public and environmental health from these constituents. Copyright © 2015 Elsevier Ltd. All rights reserved.

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

International Nuclear Information System (INIS)

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

Enhancing phytoextraction: the effect of chemical soil manipulation on mobility, plant accumulation, and leaching of heavy metals.

Science.gov (United States)

Schmidt, Ulrich

2003-01-01

For heavy metal-contaminated agricultural land, low-cost, plant-based phytoextraction measures can be a key element for a new land management strategy. When agents are applied into the soil, the solubility of heavy metals and their subsequent accumulation by plants can be increased, and, therefore, phytoextraction enhanced. An overview is given of the state of the art of enhancing heavy metal solubility in soils, increasing the heavy metal accumulation of several high-biomass-yielding and metal-tolerant plants, and the effect of these measures on the risk of heavy metal leaching. Several organic as well as inorganic agents can effectively and specifically increase solubility and, therefore, accumulation of heavy metals by several plant species. Crops like willow (Salix viminalis L.), Indian mustard [Brassica juncea (L.) Czern.], corn (Zea mays L.), and sunflower (Helianthus annuus L.) show high tolerance to heavy metals and are, therefore, to a certain extent able to use the surpluses that originate from soil manipulation. More than 100-fold increases of lead concentrations in the biomass of crops were reported, when ethylenediaminetetraacetic acid (EDTA) was applied to contaminated soils. Uranium concentrations could be strongly increased when citric acid was applied. Cadmium and zinc concentrations could be enhanced by inorganic agents like elemental sulfur or ammonium sulfate. However, leaching of heavy metals due to increased mobility in soils cannot be excluded. Thus, implementation on the field scale must consider measures to minimize leaching. So, the application of more than 1 g EDTA kg(-1) becomes inefficient as lead concentration in crops is not enhanced and leaching rate increases. Moreover, for large-scale applications, agricultural measures as placement of agents, dosage splitting, the kind and amount of agents applied, and the soil properties are important factors governing plant growth, heavy metal concentrations, and leaching rates. Effective

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

Science.gov (United States)

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.

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

International Nuclear Information System (INIS)

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)

Acid leaching of uranium present in a residue from mining industry

Energy Technology Data Exchange (ETDEWEB)

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

2011-07-01

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

Acid leaching of uranium present in a residue from mining industry

International Nuclear Information System (INIS)

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)

Metal leaching from refinery waste hydroprocessing catalyst.

Science.gov (United States)

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.

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

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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.

Continuous leaching modifies the surface properties and metal(loid) sorption of sludge-derived biochar.

Science.gov (United States)

Feng, Mingyu; Zhang, Weihua; Wu, Xueyong; Jia, Yanming; Jiang, Chixiao; Wei, Hang; Qiu, Rongliang; Tsang, Daniel C W

2018-06-01

After the application of sludge derived biochar (SDBC) for soil stabilization, it is subjected to continuous leaching that may change its surface properties and metal(loid) immobilization performance. This study simulated the continuous leaching through the fresh SDBC sample in columns with unsaturated and saturated zones under flushing with 0.01M NaNO 3 solution (pH5.5) and acidic solution (pH adjusted to 3.2 by HNO 3 :H 2 SO 4 =1:2), respectively. The resultant changes were assessed in terms of the SDBC surface characteristics and metal(loid) sorption capacities. Continuous leaching was found to gradually decrease the density of basic functional groups and increase the density of carboxyl groups as well as cation exchange capacity on the SDBC surface. It was attributed to the surface acidification and oxidation process by the leaching process, yet it occurred to a lesser extent than the atmospheric exposure. Continuous leaching increased Pb(II), Cr(VI), and As(III) sorption capacity of the SDBC, probably because the increase in carboxyl groups promoted inner-sphere complexation and Fe oxidation as revealed by spectroscopic analysis. It was noteworthy that the SDBC in the unsaturated and saturated zones under continuous leaching displayed distinctive effects on metal(loid) sorption capacity than the atmospheric exposure. Future investigations are needed for understanding the fate and interactions of the SDBC under varying redox conditions and intermittent leaching process. Copyright © 2017. Published by Elsevier B.V.

Acid extraction of molybdenum, nickel and cobalt from mineral sludge generated by rainfall water at a metal recycling plant.

Science.gov (United States)

Vemic, M; Bordas, F; Guibaud, G; Comte, S; Joussein, E; Lens, P N L; Van Hullebusch, E D

2016-01-01

This study investigated the leaching yields of Mo, Ni and Co from a mineral sludge of a metal recycling plant generated by rainfalls. The investigated mineral sludge had a complex heterogeneous composition, consisting of particles of settled soil combined with metal-bearing particles (produced by catalysts, metallic oxides and battery recycling). The leaching potential of different leaching reagents (stand-alone strong acids (HNO3 (68%), H2SO4 (98%) and HCl (36%)) and acid mixtures (aqua regia (nitric + hydrochloric (1:3)), nitric + sulphuric (1:1) and nitric + sulphuric + hydrochloric (2:1:1)) was investigated at changing operational parameters (solid-liquid (S/L) ratio, leaching time and temperature), in order to select the leaching reagent which achieves the highest metal leaching yields. Sulphuric acid (98% H2SO4) was found to be the leachant with the highest metal leaching potential. The optimal leaching conditions were a three-stage successive leaching at 80 °C with a leaching time of 2 h and S/L ratio of 0.25 g L(-1). Under these conditions, the achieved mineral sludge sample leaching yields were 85.5%, 40.5% and 93.8% for Mo, Ni and Co, respectively. The higher metal leaching potential of H2SO4 in comparison with the other strong acids/acid mixtures is attributed to the fact that H2SO4 is a diacidic compound, thus it has more H(+) ions, resulting in its stronger oxidizing power and corrosiveness.

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

International Nuclear Information System (INIS)

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)

Using microbiological leaching method to remove heavy metals from sludge

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Zhuyu Gu

2017-01-01

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

Vanadium Extraction from Shale via Sulfuric Acid Baking and Leaching

Science.gov (United States)

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.

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

Science.gov (United States)

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.

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

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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.

The use of a biodegradable chelator for enhanced phytoextraction of heavy metals by Festuca arundinacea from municipal solid waste compost and associated heavy metal leaching.

Science.gov (United States)

Zhao, Shulan; Jia, Lina; Duo, Lian

2013-02-01

In a column experiment with horizontal permeable barriers, the effects of a biodegradable chelator-nitrilotriacetic acid (NTA) on the uptake of heavy metals from municipal solid waste (MSW) compost by Festuca arundinacea and metal leaching were investigated. The use of NTA was effective in increasing Cu, Pb, and Zn uptakes in shoots of two crops of F. arundinacea. In columns with barriers and treated with 20 mmol NTA per kg MSW compost, metal uptakes by the first and second crop of F. arundinacea were, respectively, 3.8 and 4.0 times for Pb, and 1.8 and 1.7 times for Zn greater with the added NTA than without it. Though NTA application mobilized metals, it caused only slight leaching of metals from MSW compost. Permeable barriers positioned between compost and soil effectively reduced metal leaching. NTA-assisted phytoextraction by turfgrass with permeable barriers to cleanup heavy metal contaminated MSW compost should be environmentally safe. Copyright © 2012 Elsevier Ltd. All rights reserved.

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

International Nuclear Information System (INIS)

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

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

Science.gov (United States)

Fang, Wen; Wei, Yonghong; Liu, Jianguo

2016-06-05

The leaching and accumulation of heavy metals are major concerns following the land application of sewage sludge compost (SSC). We comparatively characterized SSC, the reference soil, and the SSC amended soil to investigate their similarities and differences regarding heavy metal leaching behavior and then to evaluate the effect of SSC land application on the leaching behavior of soil. Results showed that organic matter, including both of particulate organic matter (POM) and dissolved organic matter (DOM), were critical factors influencing heavy metal leaching from both of SSC and the soil. When SSC was applied to soil at the application rate of 48t/ha, the increase of DOM content slightly enhanced heavy metal leaching from the amended soil over the applicable pH domain (6leaching behavior of heavy metals. The geochemical speciation modeling revealed that heavy metal speciation in the solid phase were similar between the reference soil and the amended soil. Copyright © 2016 Elsevier B.V. All rights reserved.

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

Science.gov (United States)

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

2017-02-01

Bio- and hydrometallurgical experimental setups at 2-l reactor scale for the processing of fly ash from municipal waste incinerators were explored. We aimed to compare chemical 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.

Hydrochloric acid leach of Agnew Lake uranium concentrate

International Nuclear Information System (INIS)

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

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

International Nuclear Information System (INIS)

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)

Bioleaching of heavy metal polluted sediment: kinetics of leaching and microbial sulfur oxidation

Energy Technology Data Exchange (ETDEWEB)

Loeser, C. [Technische Universitaet Dresden, Institut fuer Lebenmitteltechnik und Bioverfahrenstechnik, D-01062 Dresden (Germany); Zehnsdorf, A. [UFZ-Umweltforschungszentrum Leipzig-Halle GmbH, Umwelt- und Biotechnologisches Zentrum (UBZ), Permoserstrasse 15, D-04318 Leipzig (Germany); Goersch, K.; Seidel, H. [UFZ-Umweltforschungszentrum Leipzig-Halle GmbH, Department Bioremediation, Permoserstrasse 15, D-04318 Leipzig (Germany)

2005-12-01

Remediation of heavy metal polluted sediment through bioleaching using elemental sulfur (S{sup 0}) as the leaching agent can be regarded as a two-step process: firstly, the microbial oxidation of the added S{sup 0} to sulfuric acid and, secondly, the reaction of the produced acid with the sediment. Here, both subprocesses were studied in detail independently: oxidized river sediment was either suspended in sulfuric acid of various strengths, or mixed with various amounts of finely ground S{sup 0} powder (diameter of the S{sup 0} particles between 1 and 175 {mu}m with a Rosin-Rammler-Sperling-Bennet (RRSB) distribution and an average diameter of 35 {mu}m) and suspended in water. The leaching process was observed by repeated analysis of the suspension concerning pH, soluble sulfate and metals, and remaining S{sup 0}. In the case of abiotic leaching with H{sub 2}SO{sub 4}, the reaction between the acid and the sediment resulted in a gradual increase in pH and a solubilization of sediment-borne heavy metals which required some time; 80 % of the finally solubilized heavy metals was dissolved after 1 h, 90 % after 10 h, and 100 % after 100 h. In the case of bioleaching, the rate of S{sup 0} oxidation was maximal at the beginning, gradually diminished with time, and was proportional to the initial amount of S{sup 0}. Due to its very low solubility in water, S{sup 0} is oxidized in a surface reaction catalyzed by attached bacteria. The oxidation let the particles shrink, their surface became smaller and, thus, the S{sup 0} oxidation rate gradually decreased. The shrinking rate was time-invariant and, at 30 C, amounted to 0.5 {mu}m/day (or 100 {mu}g/cm{sup 2}/day). Within 21 days, 90 % of the applied S{sup 0} was oxidized. Three models with a different degree of complexity have been developed that describe this S{sup 0} oxidation, assuming S{sup 0} particles of uniform size (I), using a measured particle size distribution (II), or applying an adapted RRSB distribution (III

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

International Nuclear Information System (INIS)

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)

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

Science.gov (United States)

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

2014-06-01

Over the past few decades, zinc smelting activities in Guizhou, China have produced numerous slag dumps, which are often dispersed on roadsides and hill slopes throughout the region. During periods of acid rain, these exposed slags release heavy metals into surface water bodies. A column leaching study was designed to test the potential release of the heavy metals cadmium (Cd), chromium (Cr), copper (Cu), lead (Pb), and zinc (Zn) under simulated acid rain events. Two slags with varying environmental exposure periods were packed in columns and subjected to leaching solutions of pH 3.5, 5.5, or DI H2O at intervals of 1, 7, 14, 28, 56d. Pulse concentrations of Cd in leachate were found above 5μg/L, Cr, Pb, and Zn >10μg/L, whereas, Cu reached 10μg/L. After five leaching events, the leachability (percentage of cumulative heavy metal leached after five leaching events as in its respective total concentration in slags) of Cd was 0.05 percent and 0.035 percent from the old and young slag, respectively. Cr (0.035 percent and 0.05 percent) was greater than Cu (0.002 percent and 0.005 percent) and Zn (0.006 percent and 0.003 percent), while the lowest leachability was observed for Pb (0.0005 percent and 0.0002 percent) from the old and young slags, respectively. Reaction rates (release amount of heavy metals in certain period of leaching) of heavy metals in the leachates demonstrated the sequence of Zn>Cr>Cd, Cu>Pb. Leaching release of heavy metals was jointly affected by the pH of leaching solution and mineral composition of slags (including chemical forms of Cd, Cr, Cu, Pb, and Zn). Environmental exposure period of slags, resulting in the alteration of minerals, could affect the release process of heavy metals in leaching as well. Copyright © 2014 Elsevier Inc. All rights reserved.

Leaching of heavy metals from steelmaking slags

Directory of Open Access Journals (Sweden)

Gomes, J. F. P

2006-12-01

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

Este articulo contiene los resultados obtenidos en ensayos de lixiviación de escorias de acero (horno electrico y cuchara ejecutados siguiendo la metodologia de flujo dinámico así como el ensayo normalizado DIN 38414-S4. El primer ensayo intenta simular el comportamiento de lixiviación de las escorias en vertedero. Para las escorias ensayadas se han complementado los ensayos con el análisis químico de los lixiviados y se ha verificado un aumento de la liberación de metales pesados. El ensayo DIN 38414-S4 se ha utilizado para evaluar la lixiviación por agua de metales pesados, en muestras de escorias originales. Despues de un año de ensayos, se han observado niveles muy bajos de lixiviación. Los elementos mas lixiviados han sido calcio y magnesio. No obstante, en los ensayos de flujo dinámico, el calcio y el magnesio lixiviados de las escorias sólidas era menor de 0,5% y el resto de los otros metales era inferior a 0,1%. Los lixiviados obtenidos con el ensayo DIN 38414-S4 presentan, como era de esperar, valores

Process optimization and kinetics for leaching of rare earth metals from the spent Ni-metal hydride batteries.

Science.gov (United States)

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

2016-05-01

Nickel-metal hydride batteries (Ni-MH) contain not only the base metals, but valuable rare earth metals (REMs) viz. La, Sm, Nd, Pr and Ce as well. In view of the importance of resource recycling and assured supply of the contained metals in such wastes, the present study has focussed on the leaching of the rare earth metals from the spent Ni-MH batteries. The conditions for the leaching of REMs from the spent batteries were optimized as: 2M H2SO4, 348K temperature and 120min of time at a pulp density (PD) of 100g/L. Under this condition, the leaching of 98.1% Nd, 98.4% Sm, 95.5% Pr and 89.4% Ce was achieved. Besides the rare earth metals, more than 90% of base metals (Ni, Co, Mn and Zn) were also leached out in this condition. Kinetic data for the dissolution of all the rare earth metals showed the best fit to the chemical control shrinking core model. The leaching of metals followed the mechanism involving the chemical reaction proceeding on the surface of particles by the lixiviant, which was corroborated by the XRD phase analysis and SEM-EDS studies. The activation energy of 7.6, 6.3, 11.3 and 13.5kJ/mol was acquired for the leaching of neodymium, samarium, praseodymium and cerium, respectively in the temperature range 305-348K. From the leach liquor, the mixed rare earth metals were precipitated at pH∼1.8 and the precipitated REMs was analyzed by XRD and SEM studies to determine the phases and the morphological features. Copyright © 2015. Published by Elsevier Ltd.

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

Science.gov (United States)

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.

Effects of extraction methods and factors on leaching of metals from recycled concrete aggregates.

Science.gov (United States)

Bestgen, Janile O; Cetin, Bora; Tanyu, Burak F

2016-07-01

Leaching of metals (calcium (Ca), chromium (Cr), copper, (Cu), iron (Fe), and zinc (Zn)) of recycled concrete aggregates (RCAs) were investigated with four different leachate extraction methods (batch water leach tests (WLTs), toxicity leaching procedure test (TCLP), synthetic precipitation leaching procedure test (SPLP), and pH-dependent leach tests). WLTs were also used to perform a parametric study to evaluate factors including (i) effects of reaction time, (ii) atmosphere, (iii) liquid-to-solid (L/S) ratio, and (iv) particle size of RCA. The results from WLTs showed that reaction time and exposure to atmosphere had impact on leaching behavior of metals. An increase in L/S ratio decreased the effluent pH and all metal concentrations. Particle size of the RCA had impact on some metals but not all. Comparison of the leached concentrations of metals from select RCA samples with WLT method to leached concentrations from TCLP and SPLP methods revealed significant differences. For the same RCA samples, the highest metal concentrations were obtained with TCLP method, followed by WLT and SPLP methods. However, in all tests, the concentrations of all four (Cr, Cu, Fe, and Zn) metals were below the regulatory limits determined by EPA MCLs in all tests with few exceptions. pH-dependent batch water leach tests revealed that leaching pattern for Ca is more cationic whereas for other metals showed more amphoteric. The results obtained from the pH-dependent tests were evaluated with geochemical modeling (MINTEQA2) to estimate the governing leaching mechanisms for different metals. The results indicated that the releases of the elements were solubility-controlled except Cr.

Reduction of metal leaching in brown coal fly ash using geopolymers

International Nuclear Information System (INIS)

Bankowski, P.; Zou, L.; Hodges, R.

2004-01-01

Current regulations classify fly ash as a prescribed waste and prohibit its disposal in regular landfill. Treatment of the fly ash can reduce the leach rate of metals, and allow it to be disposed in less prescribed landfill. A geopolymer matrix was investigated as a potential stabilisation method for brown coal fly ash. Precipitator fly ash was obtained from electrostatic precipitators and leached fly ash was collected from ash disposal ponds, and leaching tests were conducted on both types of geopolymer stabilised fly ashes. The ratio of fly ash to geopolymer was varied to determine the effects of different compositions on leaching rates. Fourteen metals and heavy metals were targeted during the leaching tests and the results indicate that a geopolymer is effective at reducing the leach rates of many metals from the fly ash, such as calcium, arsenic, selenium, strontium and barium. The major element leachate concentrations obtained from leached fly ash were in general lower than that of precipitator fly ash. Conversely, heavy metal leachate concentrations were lower in precipitator fly ash than leached pond fly ash. The maximum addition of fly ash to this geopolymer was found to be 60 wt% for fly ash obtained from the electrostatic precipitators and 70 wt% for fly ash obtained from ash disposal ponds. The formation of geopolymer in the presence of fly ash was studied using 29Si MAS-NMR and showed that a geopolymer matrix was formed. X-ray diffraction (XRD) analysis and scanning electron microscopy (SEM) imaging showed the interaction of the fly ash with the geopolymer, which was related to the leachate data and also the maximum percentage fly ash addition

Comparison of the ability of organic acids and EDTA to enhance the phytoextraction of metals from a multi-metal contaminated soil.

Science.gov (United States)

Kim, Sung-Hyun; Lee, In-Sook

2010-02-01

Chelates have been shown to enhance the phytoextraction of metal from contaminated soil. In this study, we evaluated the ability of chelates to enhance the phytoextraction of metals by barnyard grass (Echinochloa crus-galli) from soils contaminated with multiple metals. The results revealed that EDTA increased the ability of barnyard grass to take up Cd, Cu and Pb, but that it resulted in increased soil leaching. Conversely, citric acid induced the removal of Cd, Cu and Pb from soil without increasing the risk of leaching. Furthermore, E.crus-galli showed no signs of phytotoxicity in response to treatment with citric acid, whereas its shoot growth decreased in response to treatment with EDTA (p acid is a good agent for the enhancement of the phytoextraction of metals.

Leaching characteristics of rare metal elements and chlorine in fly ash from ash melting plants for metal recovery.

Science.gov (United States)

Jung, Chang-Hwan; Osako, Masahiro

2009-05-01

In terms of resource recovery and environmental impact, melting furnace fly ash (MFA) is attracting much attention in Japan due to its high metal content. The study aims to obtain fundamental information on using a water extraction method not only to concentrate valuable rare metals but also to remove undesirable substances such as chlorine for their recovery from MFA. The composition and leaching characteristics of MFA was investigated. The results revealed that the metal content in MFA is nearly equal to raw ore quality. The content of Ag, In, Pd, Pb, and Zn is, in fact, higher than the content of raw ore. As for leaching behavior, Ag, Bi, In, Ga, Ge, Sb, Sn, and Te showed the lowest release at a neutral pH range. Pd was leached constantly regardless of pH, but its concentration was quite low. On the other hand, most of the Tl was easily leached, revealing that water extraction is not appropriate for Tl recovery from MFA. Major elements Cl, Ca, Na, and K, occupying about 70% of MFA, were mostly leached regardless of pH. Base metal elements Cu, Pb, and Zn showed minimum solubility at a neutral pH. The leaching ratio of target rare metal elements and base metal elements suggests that the optimal pH for water extraction is 8-10, at which the leaching concentration is minimized. The water extraction process removed most of the Cl, Ca, Na, and K, and the concentration of rare metals and base metals increased by four or five times.

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

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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.

Heavy metal leaching from mine tailings as affected by plants

Energy Technology Data Exchange (ETDEWEB)

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.

Assessment of metal contaminations leaching out from recycling plastic bottles upon treatments.

Science.gov (United States)

Cheng, Xiaoliang; Shi, Honglan; Adams, Craig D; Ma, Yinfa

2010-08-01

Heavy metal contaminants in environment, especially in drinking water, are always of great concern due to their health impact. Due to the use of heavy metals as catalysts during plastic syntheses, particularly antimony, human exposure to metal release from plastic bottles has been a serious concern in recent years. The aim and scope of this study were to assess metal contaminations leaching out from a series of recycling plastic bottles upon treatments. In this study, leaching concentrations of 16 metal elements were determined in 21 different types of plastic bottles from five commercial brands, which were made of recycling materials ranging from no. 1 to no. 7. Several sets of experiments were conducted to study the factors that could potentially affect the metal elements leaching from plastic bottles, which include cooling with frozen water, heating with boiling water, microwave, incubating with low-pH water, outdoor sunlight irradiation, and in-car storage. Heating and microwave can lead to a noticeable increase of antimony leaching relative to the controls in bottle samples A to G, and some even reached to a higher level than the maximum contamination level (MCL) of the US Environmental Protection Agency (USEPA) regulations. Incubation with low-pH water, outdoor sunlight irradiation, and in-car storage had no significant effect on antimony leaching relative to controls in bottle samples A to G, and the levels of antimony leaching detected were below 6 ppb which is the MCL of USEPA regulations. Cooling had almost no effect on antimony leaching based on our results. For the other interested 15 metal elements (Al, V, Cr, Mn, Co, Ni, Cu, As, Se, Mo, Ag, Cd, Ba, Tl, Pb), no significant leaching was detected or the level was far below the MCL of USEPA regulations in all bottle samples in this study. In addition, washing procedure did contribute to the antimony leaching concentration for polyethylene terephthalate (PET) bottles. The difference of antimony leaching

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

Science.gov (United States)

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.

Leaching behavior of heavy metals from municipal solid wastes incineration (MSWI) fly ash used in concrete

International Nuclear Information System (INIS)

Shi Huisheng; Kan Lili

2009-01-01

The characteristics of municipal solid waste incineration (MSWI) fly ash, surface leaching toxicity and successive leaching concentration of heavy metals from MSWI fly ash-cement hardened pastes were studied. And, the relationships between leaching concentrations of heavy metals and leaching time were also discussed. Experimental results showed that immobilization effect of cement on MSWI fly ash is good. Even if MSWI fly ash-cement hardened pastes were damaged, the leaching toxicity is still in a safety range. In early leaching stage, the surface leaching rate is relatively a little high, up to 10 -5 -10 -4 cm d -1 order of magnitude, in the later time of leaching, its rate rapidly declined, down to 10 -7 . Most of leached heavy metals are produced at early ages. The leaching concentration of heavy metals and leaching time has strong positive relationships. In factual utilizing circumstances, heavy metals' leaching from MSWI fly ash-cement hardened pastes is a very slow and gradually diluting process. The leaching toxicity of heavy metals is far lower than that of the National Standard of China, and minimum harmful matters can be contained and released in the environment. Reusing of MSWI fly ash as partial replacement for cement in concrete mixes is potentially feasible.

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

Directory of Open Access Journals (Sweden)

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.

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

Directory of Open Access Journals (Sweden)

Sokić M.

2012-01-01

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

Hydrometallurgical process for the recovery of metal values from spent lithium-ion batteries in citric acid media.

Science.gov (United States)

Chen, Xiangping; Zhou, Tao

2014-11-01

In this paper, a hydrometallurgical process has been proposed to recover valuable metals from spent lithium-ion batteries in citric acid media. Leaching efficiencies as high as 97%, 95%, 94%, and 99% of Ni, Co, Mn, and Li were achieved under the optimal leaching experimental conditions of citric acid concentration of 2 mol L(-1), leaching temperature of 80 °C, leaching time of 90 min, liquid-solid ratio of 30 ml g(-1), and 2 vol. % H2O2. For the metals recovery process, nickel and cobalt were selectively precipitated by dimethylglyoxime reagent and ammonium oxalate sequentially. Then manganese was extracted by Na-D2EHPA and the manganese-loaded D2EHPA was stripped with sulfuric acid. The manganese was recovered as MnSO4 in aqueous phase and D2EHPA could be reused after saponification. Finally, lithium was precipitated by 0.5 mol L(-1) sodium phosphate. Under their optimal conditions, the recovery percentages of Ni, Co, Mn, and Li can reach 98%, 97%, 98%, and 89%, respectively. This is a relatively simple route in which all metal values could be effectively leached and recovered in citric acid media. © The Author(s) 2014.

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

Institute of Scientific and Technical Information of China (English)

ZHEN Yulan; ZHANG Guohua; CHOU Kuochih

2016-01-01

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

Heavy Metal Leaching as Affected by Long-Time Organic Waste Fertilizer Application.

Science.gov (United States)

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.

Investigations of metal leaching from mobile phone parts using TCLP and WET methods.

Science.gov (United States)

Yadav, Satyamanyu; Yadav, Sudesh

2014-11-01

Metal leaching from landfills containing end-of-life or otherwise discarded mobile phones poses a threat to the environment as well as public health. In the present study, the metal toxicity of printed wire boards (PWBs), plastics, liquid crystal displays (LCDs) and batteries of mobile phones was assessed using the Toxicity Characteristics Leaching Procedures (TCLP) and the Waste Extraction Test (WET). The PWBs failed TCLP for Pb and Se, and WET for Pb and Zn. In WET, the two PWB samples for Pb and Zn and the battery samples for Co and Cu failed the test. Furthermore, the PWBS for Ni and the battery samples for Ni and Co failed the WET in their TCLP leachates. Both, Ni and Co are the regulatory metals in only WET and not covered under TCLP. These observations indicate that the TCLP seems to be a more aggressive test than the WET for the metal leaching from the mobile phone parts. The compositional variations, nature of leaching solution (acetate in TCLP and citrate in WET) and the redox conditions in the leaching solution of the PWBs resulted in different order of metals with respect to their amounts of leaching from PWBs in TCLP (Fe > Pb > Zn > Ni > Co > Cu) and WET (Zn > Fe > Ni > Pb > Cu). The metal leaching also varied with the make, manufacturing year and part of the mobile phone tested. PWBs, plastics and batteries should be treated as hazardous waste. Metal leaching, particularly of Se and Pb, from mobile phones can be harmful to the environment and human health. Therefore, a scientifically sound and environmentally safe handling and disposal management system needs to be evolved for the mobile phone disposal. Copyright © 2014 Elsevier Ltd. All rights reserved.

Leaching of sodium carbonate cakes by nitric acid

International Nuclear Information System (INIS)

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%

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

Energy Technology Data Exchange (ETDEWEB)

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

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

International Nuclear Information System (INIS)

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

Assessment of heavy metals leaching from (biochar obtained from industrial sewage sludge

Directory of Open Access Journals (Sweden)

Julija Pečkytė

2015-10-01

Full Text Available Biochar can be produced from many various feedstock including biomass residues such as straw, branches, sawdust and other agricultural and forestry waste. One of the alternatives is to obtain biochar from industrial sewage sludge, however, the use of such a product could be limited due to high quantities of heavy metals in the biochar as a product. Total concentration of heavy metals provides only limited information on the behavior of heavy metals, therefore, batch leaching and up-flow percolation leaching tests were applied to study the leaching of heavy metals (Cd, Pb, Cr, Ni, Zn, Cu from (biochar produced from two types of sewage sludge: from paper mill and leather industries.

The effect of environmental conditions on the stability of heavy metal-filter material complex as assessed by the leaching of adsorbed metal ions

Energy Technology Data Exchange (ETDEWEB)

Khokhotva, Oleksandr, E-mail: khokhotva@bigmir.net [School of Sustainable Development of Society and Technology, Maelardalen University, Box 883, SE-721 23, Vaesteras (Sweden); Waara, Sylvia, E-mail: sylvia.waara@hh.se [School of Sustainable Development of Society and Technology, Maelardalen University, Box 883, SE-721 23, Vaesteras (Sweden)

2011-06-15

In this study the influence of environmental conditions, most likely prevailing in filter beds used for intermittently discharged pollutant streams such as landfill leachate and storm water, on the stability of the heavy metal-filter complex was investigated for 2 filter materials; non-treated and urea treated pine bark, using leaching experiments. The metal-filter complex stability was higher for urea treated than for non-treated pine bark and dependent on the metal adsorbed. The type of environmental condition applied was of less importance for the extent of leaching. - Highlights: > Metal-pine bark complex stability under changing environmental conditions is studied. > Metal leaching from non-treated bark is much higher than from urea-treated bark. > No significant influence of changing environmental conditions on the leaching extent. > Metal leaching from wet bark samples exposed to freezing is somewhat higher.> Zn leaching is the highest and Cu leaching is the lowest for both bark samples. - The study assess the metal-filter material complex stability when metal removal using filter material is used in locations with fluctuating environmental conditions.

The effect of environmental conditions on the stability of heavy metal-filter material complex as assessed by the leaching of adsorbed metal ions

International Nuclear Information System (INIS)

Khokhotva, Oleksandr; Waara, Sylvia

2011-01-01

In this study the influence of environmental conditions, most likely prevailing in filter beds used for intermittently discharged pollutant streams such as landfill leachate and storm water, on the stability of the heavy metal-filter complex was investigated for 2 filter materials; non-treated and urea treated pine bark, using leaching experiments. The metal-filter complex stability was higher for urea treated than for non-treated pine bark and dependent on the metal adsorbed. The type of environmental condition applied was of less importance for the extent of leaching. - Highlights: → Metal-pine bark complex stability under changing environmental conditions is studied. → Metal leaching from non-treated bark is much higher than from urea-treated bark. → No significant influence of changing environmental conditions on the leaching extent. → Metal leaching from wet bark samples exposed to freezing is somewhat higher.→ Zn leaching is the highest and Cu leaching is the lowest for both bark samples. - The study assess the metal-filter material complex stability when metal removal using filter material is used in locations with fluctuating environmental conditions.

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

International Nuclear Information System (INIS)

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

Manual of acid in situ leach uranium mining technology

International Nuclear Information System (INIS)

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

Manual of acid in situ leach uranium mining technology

Energy Technology Data Exchange (ETDEWEB)

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.

[Leaching characteristics of heavy metals and utilization of filter media in BAF].

Science.gov (United States)

Zou, Jin-long; Dai, Ying

2007-10-01

A series of leaching tests were conducted to study the solidification of heavy metals in biological filter media made with dried sludge as an additive. The maximum leaching contents of Cd, Cr, Cu and Pb are obtained when pH is 1; leaching contents of heavy metals have an obvious decrease as pH is greater than or equal to 3; and it can be concluded from the results that pH has a significant influence on the leaching characteristic of heavy metals at leaching time of either 24 h or 30 d. X-ray diffraction analysis performed on filter media reveal the main compounds of the 4 heavy metals are Pb2O(CrO4), CdSiO3 and CuO, and the heavy metals are solidified in the mesh structure of Si--O. Heavy metals (such as Cd, Cr, Cu and Pb) can be solidified in filter media through a series of crystalline phase changes and chemical reaction after high temperature sintering. The new filter media (obtained in test) were used in biological aerated filter (BAF) to treat wastewater (C/N about 11.5 and 25.5) in a simultaneous nitrification and denitrification (SND) system. Based on the mechanism of SND, the average removal efficienciesof NH4(+)-N and TN filled with the new filter media (obtained in test) are about 85.5%, 90.3%, 46.6% and 49.6%, respectively, and it is higher than those of other 3 medias (Jiangxi ceramsite, Guangzhou ceramsite and Shanxi activated carbon). The results provide a better understanding of factors that may affect the immobilization and leaching characteristics of heavy metals in ceramsite, which promotes the extensive use of filter media in BAF.

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

Science.gov (United States)

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.

Solvent extraction of uranium from high acid leach solution

International Nuclear Information System (INIS)

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

Comparison of leaching characteristics of heavy metals from bottom and fly ashes in Korea and Japan.

Science.gov (United States)

Shim, Young-Sook; Rhee, Seung-Whee; Lee, Woo-Keun

2005-01-01

The objective of this research was to compare the leaching characteristics of heavy metals such as cadmium, chromium, copper, nickel, lead, etc., in Korean and Japanese municipal solid waste incineration (MSWI) ash. The rate of leaching of heavy metal was measured by KSLT and JTL-13, and the amount of heavy metals leached was compared with the metal content in each waste component. Finally, bio-availability testing was performed to assess the risks associated with heavy metals leached from bottom ash and fly ash. From the results, the value of neutralization ability in Japanese fly ash was four times higher than that in Korean fly ash. The reason was the difference in the content of Ca(OH)(2) in fly ash. The amount of lead leached exceeded the regulatory level in both Japanese and Korean fly ash. The rate of leaching was relatively low in ash with a pH in the range of 6-10. The bio-availability test in fly ash demonstrated that the amount of heavy metals leached was Pb>Cd>Cr, but the order was changed to Pb>Cr>Cd in the bottom ash. The leaching concentration of lead exceeded the Japanese risk level in all fly ashes from the two countries, but the leaching concentration of cadmium exceeded the regulatory level in Korean fly ash only.

Comparison of leaching characteristics of heavy metals from bottom and fly ashes in Korea and Japan

International Nuclear Information System (INIS)

Shim, Young-Sook; Rhee, Seung-Whee; Lee, Woo-Keun

2005-01-01

The objective of this research was to compare the leaching characteristics of heavy metals such as cadmium, chromium, copper, nickel, lead, etc., in Korean and Japanese municipal solid waste incineration (MSWI) ash. The rate of leaching of heavy metal was measured by KSLT and JTL-13, and the amount of heavy metals leached was compared with the metal content in each waste component. Finally, bio-availability testing was performed to assess the risks associated with heavy metals leached from bottom ash and fly ash. From the results, the value of neutralization ability in Japanese fly ash was four times higher than that in Korean fly ash. The reason was the difference in the content of Ca(OH) 2 in fly ash. The amount of lead leached exceeded the regulatory level in both Japanese and Korean fly ash. The rate of leaching was relatively low in ash with a pH in the range of 6-10. The bio-availability test in fly ash demonstrated that the amount of heavy metals leached was Pb > Cd > Cr, but the order was changed to Pb > Cr > Cd in the bottom ash. The leaching concentration of lead exceeded the Japanese risk level in all fly ashes from the two countries, but the leaching concentration of cadmium exceeded the regulatory level in Korean fly ash only

Leaching of heavy metals from contaminated soils using inductively coupled plasma optical emission spectrometer (ICP-OES) and atomic absorption spectrometer (AAS)

International Nuclear Information System (INIS)

Hussain, Z.; Islam, M.

2010-01-01

The clean-up of soils contaminated with heavy metals is one of the most difficult tasks for environmental engineering. Heavy metals are highly persistent in soil and a number of techniques have been developed that aim to remove heavy metals from contaminated soil. A method has been adopted to evaluate dynamic leaching of metal contaminants from industrial soil samples obtained from textile industrial sites in Lahore, Pakistan. In the extraction procedures employed five different leaching liquors were used: 0.01 M CaCl/sub 2/, 1 M HNO/sub 3/, a 1:1 mixture of 0.1M HCl and 0.1M NaCl, 0.01 M EDTA and pH controlled 0.5 M acetic acid. The qualitative and quantitative analyses were carried out by Atomic Absorption Spectroscopy (AAS) and Inductively Coupled Plasma-Optical Emission Spectrometer (ICP-OES). The results indicate that Cu, Zn, Cd, Ni, Pb, Fe and As were extracted in the soil samples in varying concentration when using the different leach liquors. The predominant metals which were leached were As 78.7 ng/ml in 0.01 M EDTA; Zn 1.81 mu g/ml and Fe 898.96 macro g/ml in HNO/sub 3/. (author)

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

Directory of Open Access Journals (Sweden)

Sara Asselin

2014-01-01

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

Speciation of heavy metals in garden soils. Evidences from selective and sequential chemical leaching

Energy Technology Data Exchange (ETDEWEB)

Cheng, Zhongqi; Lee, Leda; Dayan, Sara; Grinshtein, Michael [Brooklyn College of The City Univ. of New York, Brooklyn, NY (United States). Environmental Sciences Analytical Cnter; Shaw, Richard [USDA-NRCS NYC Soil Survey, Staten Island, NY (United States)

2011-06-15

Purpose: Gardening (especially food growing) in urban areas is becoming popular, but urban soils are often very contaminated for historical reasons. There is lack of sufficient information as to the bioavailability of soil heavy metals to plants and human in urban environments. This study examines the relative leachability of Cr, Ni, As, Cd, Zn, and Pb for soils with varying characteristics. The speciation and mobility of these metals can be qualitatively inferred from the leaching experiments. The goal is to use the data to shed some light on their bioavailability to plant and human, as well as the basis for soil remediation. Materials and methods: Selective and sequential chemical leaching methods were both used to evaluate the speciation of Cr, Ni, As, Cd, Zn, and Pb in soil samples collected from New York City residential and community gardens. The sequential leaching experiment followed a standard BCR four-step procedure, while selective leaching involved seven different chemical extractants. Results and discussion: The results from selective and sequential leaching methods are consistent. In general, very little of the heavy metals were found in the easily soluble or exchangeable fractions. Larger fractions of Cd and Zn can be leached out than other metals. Lead appears predominantly in the organic or carbonate fractions, of which {proportional_to} 30-60% is in the easily soluble organic fraction. Most As cannot be leached out by any of the extractants used, but it could have been complicated by the ineffective dissolution of oxides by ammonium hydroxylamine. Ni and Cr were mostly in the residual fractions but some released in the oxidizable fractions. Therefore, the leachability of metals follow the order Cd/Zn > Pb > Ni/Cr. Conclusions: Despite of the controversy and inaccuracy surrounding chemical leaching methods for the speciation of metals, chemical leaching data provide important, general, and easy-to-access information on the mobility of heavy metals

Spent lithium-ion battery recycling - Reductive ammonia leaching of metals from cathode scrap by sodium sulphite.

Science.gov (United States)

Zheng, Xiaohong; Gao, Wenfang; Zhang, Xihua; He, Mingming; Lin, Xiao; Cao, Hongbin; Zhang, Yi; Sun, Zhi

2017-02-01

Recycling of spent lithium-ion batteries has attracted wide attention because of their high content of valuable and hazardous metals. One of the difficulties for effective metal recovery is the separation of different metals from the solution after leaching. In this research, a full hydrometallurgical process is developed to selectively recover valuable metals (Ni, Co and Li) from cathode scrap of spent lithium ion batteries. By introducing ammonia-ammonium sulphate as the leaching solution and sodium sulphite as the reductant, the total selectivity of Ni, Co and Li in the first-step leaching solution is more than 98.6% while it for Mn is only 1.36%. In detail understanding of the selective leaching process is carried out by investigating the effects of parameters such as leaching reagent composition, leaching time (0-480min), agitation speed (200-700rpm), pulp density (10-50g/L) and temperature (323-353K). It was found that Mn is primarily reduced from Mn 4+ into Mn 2+ into the solution as [Formula: see text] while it subsequently precipitates out into the residue in the form of (NH 4 ) 2 Mn(SO 3 ) 2 ·H 2 O. Ni, Co and Li are leached and remain in the solution either as metallic ion or amine complexes. The optimised leaching conditions can be further obtained and the leaching kinetics is found to be chemical reaction control under current leaching conditions. As a result, this research is potentially beneficial for further optimisation of the spent lithium ion battery recycling process after incorporating with metal extraction from the leaching solution. Copyright © 2016 Elsevier Ltd. All rights reserved.

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

Directory of Open Access Journals (Sweden)

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

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

Directory of Open Access Journals (Sweden)

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.

Sulfur dioxide leaching of spent zinc-carbon-battery scrap

Energy Technology Data Exchange (ETDEWEB)

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)

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

Science.gov (United States)

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

2015-11-01

The purpose of Directive 2012/19/EU which is related to WEEE (Waste Electrical and Electronic Equipment), also known as "e-waste", is to contribute to their sustainable production and consumption that would most possibly be achieved by their recovery, recycling and reuse. Under this perspective, the present study focused on the recovery of valuable materials, metals and metalloids from LCDs (Liquid Crystal Displays). Indium (In), arsenic (As) and stibium (Sb) were selected to be examined for their Leaching Capacity (R) from waste LCDs. Indium was selected mainly due to its rarity and preciousness, As due to its high toxicity and wide use in LCDs and Sb due to its recent application as arsenic's replacement to improve the optimal clarity of a LCD screen. The experimental procedure included disassembly of screens along with removal and recovery of polarizers via thermal shock, cutting, pulverization and digestion of the shredded material and finally leaching evaluation of the aforementioned elements. Leaching tests were conducted under various temperatures, using various solid:liquid (S/L) ratios and solvents (acid mixtures), to determine the optimal conditions for obtaining the maximum leaching capacities. The examined elements exhibited different leaching behaviors, mainly due to the considerable diversity in their inherent characteristic properties. Indium demonstrated the highest recovery percentages (approximately 60%), while the recovery of As and Sb was unsuccessful, obtaining poor leaching percentages (0.16% and 0.5%, respectively). Copyright © 2015 Elsevier Ltd. All rights reserved.

Extraction of magnesium from calcined dolomite ore using hydrochloric acid leaching

Science.gov (United States)

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.

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

International Nuclear Information System (INIS)

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.)

Hydrometallurgical Approach for Leaching of Metals from Copper Rich Side Stream Originating from Base Metal Production

Directory of Open Access Journals (Sweden)

Udit Surya Mohanty

2018-01-01

Full Text Available Pyrometallurgical metal production results in side streams, such as dusts and slags, which are carriers of metals, though commonly containing lower metal concentrations compared to the main process stream. In order to improve the circular economy of metals, selective leaching of copper from an intermediate raw material originating from primary base metal production plant was investigated. The raw material investigated was rich in Cu (12.5%, Ni (2.6%, Zn (1.6%, and Fe (23.6% with the particle size D80 of 124 µm. The main compounds present were nickel ferrite (NiFe2O4, fayalite (Fe2SiO4, cuprite (Cu2O, and metallic copper. Leaching was studied in 16 different solutions. The results revealed that copper phases could be dissolved with high yield (>90% and selectivity towards nickel (Cu/Ni > 7 already at room temperature with the following solutions: 0.5 M HCl, 1.5 M HCl, 4 M NaOH, and 2 M HNO3. A concentration of 4 M NaOH provided a superior selectivity between Cu/Ni (340 and Cu/Zn (51. In addition, 1–2 M HNO3 and 0.5 M HCl solutions were shown to result in high Pb dissolution (>98%. Consequently, 0.5 M HCl leaching is suggested to provide a low temperature, low chemical consumption method for selective copper removal from the investigated side stream, resulting in PLS (pregnant leach solution which is a rich in Cu and lead free residue, also rich in Ni and Fe.

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

Science.gov (United States)

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.

A Method for Suppression of Active Metal Leaching during the Direct Synthesis of H{sub 2}O{sub 2} by Using Polyelectrolyte Multilayers

Energy Technology Data Exchange (ETDEWEB)

Chung, Young-Min [Kunsan National University, Kunsan (Korea, Republic of)

2015-04-15

In this study, two types of catalysts were prepared via conventional metal supporting method and encapsulation of metal nanoparticles in the polyelectrolyte multilayers constructed on support. The resulting catalysts were applied to the direct synthesis of hydrogen peroxide, and the effect of catalyst preparation method on the catalyst life as well as hydrogen peroxide productivity was investigated. The catalytic activity was strongly dependent upon the acid strength of support regardless of the catalyst preparation methods and HBEA (SAR=25) with strong acidity was superior to other supports to promote the reaction. In the case of metal supported catalyst, while hydrogen peroxide productivity was higher than that of polyelectrolyte multilayered counterpart, the reaction performance was sharply decreased during catalyst recycling due to the metal leaching. On the other hand, construction of polyelectrolyte multilayers on support weakened the influence of acid support on the reaction medium and therefore resulted in the decrease of catalytic activity and the increase of hydrogen peroxide decomposition as well. It is noted, however, that the catalytic activity was maintained after 5 recycles, which suggests that the introduction of polyelectrolyte multilayers on the support is very effective to suppress the unfavorable metal leaching phenomenon during a reaction.

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

Science.gov (United States)

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

Directions of development of research methods in the assessment of leaching of heavy metals from mineral waste

Directory of Open Access Journals (Sweden)

Król Anna

2016-01-01

Full Text Available There are many test methods to assess the level of the release of heavy metals into the environment from mineral waste materials. Leaching methods can be different depending on the leaching time periods, leaching dynamics, sample preparation method or the pH of the elution medium. In Poland, little attention is paid to the research on the relationship between the leaching of particular heavy metals from mineral wastes and changes in environmental conditions, including the pH of the environment. Tests being carried out abroad have started to pay great attention to the pH-dependent impact of the environment and the liquid being in contact with the material on the degree of leaching contaminants from wastes. The solubility of all metals depends on the value of the pH. Authors of the paper will try to prove that Polish methods of waste characterization is incomplete and inconsistent with opinions prevailing in the global literature. The procedure described in the Polish standards are insufficient to determine the actual level of leaching of heavy metals having regard to the impact of multiple external conditions on the level of leaching of heavy metals. Paper will present a directions of development of research methods in the assessment of leaching of heavy metals from mineral waste.

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

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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%.

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

International Nuclear Information System (INIS)

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

Study of hydrated Portland cement composition in regard to leaching resistance

NARCIS (Netherlands)

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

Bottle roll leach test for Temrezli uranium ore

International Nuclear Information System (INIS)

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)

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

Science.gov (United States)

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.

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

International Nuclear Information System (INIS)

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.)

Leaching of metals from sewage sludge during one year and their relationship to particle size

International Nuclear Information System (INIS)

Ahlberg, G.; Gustafsson, O.; Wedel, P.

2006-01-01

Leaching of metals from sewage sludge can lead to their accumulation in topsoil and can also contaminate groundwater. Our objectives were to document the metal leachates and the size distribution of leached particles from sewage sludge and to identify possible correlations with physical factors. Results from monthly lysimeter sampling showed an initial release followed by decline for most metals. Cadmium, Ca, Sr, Li, Mn, Ni and Zn showed a 'cyclic' behaviour. Filtration revealed that this 'cyclicity' had no correlation to the size of released particles, but Al, Cr, Fe, Cu, Ag and Pb were clearly related to release of coarser particles most of the year. Total metal amounts leached during one year, relative to original sludge content, had the order Na > Ca = Mg > Mn > Sr > Zn > K > Li = Ni > Cd > Co > Rb > Ag > Cr > Ba = Cu > Ga > Al = Pb = Fe. There were no simple correlations between monthly measured leachate concentrations and precipitation, temperature or pH of precipitation. Occasional leachate sampling might give misleading values for metals with 'cyclic' behaviour. - Cyclic leaching patterns of metals from sewage sludge deserve attention

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

NARCIS (Netherlands)

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

1998-01-01

The present paper addresses cement compositions that have an optimal resistance against acid attack and hence, low leaching rates and optimal waste containment. To this end a shrinking core leaching model is used that describes the leaching of metals from a cement sample. This process is directly

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

International Nuclear Information System (INIS)

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)

Microbial leaching of iron from pyrite by moderate thermophile chemolithotropic bacteria

International Nuclear Information System (INIS)

Ilyas, S.; Niazi, S.B.

2007-01-01

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

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

Science.gov (United States)

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.

Environmental Hazard Assessment of Jarosite Waste Using Batch Leaching Tests

Directory of Open Access Journals (Sweden)

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.

THE INFLUENCE OF SELECTED FACTORS ON THE LEACHING OF HEAVY METALS FROM SMELTER WASTE

OpenAIRE

Kamila Mizerna; Anna Król

2015-01-01

The paper presents the results of leaching research of selected heavy metals (Pb, Cu, Zn, Ni, Cd, Cr) from industrial waste. The impact of waste fragmentation on the level of heavy metals leaching was analyzed. The decrease of copper and zinc release and the increase of nickel leaching were observed with increasing grain size fraction of waste. Furthermore, release of contaminants in different ratio of liquid to solid (L/S = 10 dm3/kg and 2 dm3/kg) was studied. Higher concentrations of heavy ...

Dissolution of Metal Supported Spent Auto Catalysts in Acids

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Fornalczyk A.

2016-03-01

Full Text Available Metal supported auto catalysts, have been used in sports and racing cars initially, but nowadays their application systematically increases. In Metal Substrate (supported Converters (MSC, catalytic functions are performed by the Platinum Group Metals (PGM: Pt, Pd, Rh, similarly to the catalysts on ceramic carriers. The contents of these metals make that spent catalytic converters are valuable source of precious metals. All over the world there are many methods for the metals recovery from the ceramic carriers, however, the issue of platinum recovery from metal supported catalysts has not been studied sufficiently yet. The paper presents preliminary results of dissolution of spent automotive catalyst on a metal carrier by means of acids: H2SO4, HCl, HNO3, H3PO4. The main assumption of the research was the dissolution of base metals (Fe, Cr, Al from metallic carrier of catalyst, avoiding dissolution of PGMs. Dissolution was the most effective when concentrated hydrochloric acid, and 2M sulfuric acid (VI was used. It was observed that the dust, remaining after leaching, contained platinum in the level of 0.8% and 0.7%, respectively.

Metal leaching from experimental coal fly-ash oyster cultch

Energy Technology Data Exchange (ETDEWEB)

Homziak, J.; Bennett, L.; Simon, P.; Herring, R. (Mississippi State University, MS (USA). Coastal Research and Extension Center)

1993-08-01

Because oysters accumulate metals far in excess of ambient concentrations potential leaching and bioaccumulation of metals may be important public health concerns where ash-cement aggregates are being considered for oyster cultivation. This study examined the potential for metal release from an ash-cement aggregate proposed for use in oyster reef construction in Mississippi coastal waters. Seven acid-washed aquaria were each filled with 77L of artificial seawater. Five randomly selected aquaria each received 8.6 L of aggregate pellets. Samples were taken from each aquarium one hour after the start of the experiment and at 10 day intervals on six subsequent sampling dates. The samples were analysed for arsenic, cadmium, chromium, copper, iron, lead, manganese, mercury, nickel, selenium and zinc. Cadmium, iron and mercury were essentially not detected in the treatment aquaria. Except for chromium, the mean concentrations of metals in the treatment samples were generally less than 10 ppb. An overall comparison of the concentrations of 8 metals among all aquaria and sampling dates detected significant differences in the concentration of chromium (p[lt]0.001), manganese (p[lt]0.05) and selenium (p[lt]0.001). Treatment aquaria had significantly greater concentrations of chromium and selenium than did either control (nonparametric multiple comparison, p[lt]0.05). Most of the chromium found in the treatment aquaria was the hexavalent form (means range from 0.052 to 1.328 ppm). Treatment hexavalent chromium concentrations increased over time. 14 refs., 1 fig., 2 tabs.

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

Directory of Open Access Journals (Sweden)

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.

Leaching of metals from end-of-life solar cells.

Science.gov (United States)

Chakankar, Mital; Su, Chun Hui; Hocheng, Hong

2018-04-10

The issue of recycling waste solar cells is critical with regard to the expanded use of these cells, which increases waste production. Technology establishment for this recycling process is essential with respect to the valuable and hazardous metals present therein. In the present study, the leaching potentials of Acidithiobacillus thiooxidans, Acidithiobacillus ferrooxidans, Penicillium chrysogenum, and Penicillium simplicissimum were assessed for the recovery of metals from spent solar cells, with a focus on retrieval of the valuable metal Te. Batch experiments were performed to explore and compare the metal removal efficiencies of the aforementioned microorganisms using spent media. P. chrysogenum spent medium was found to be most effective, recovering 100% of B, Mg, Si, V, Ni, Zn, and Sr along with 93% of Te at 30 °C, 150 rpm and 1% (w/v) pulp density. Further optimization of the process parameters increased the leaching efficiency, and 100% of Te was recovered at the optimum conditions of 20 °C, 200 rpm shaking speed and 1% (w/v) pulp density. In addition, the recovery of aluminum increased from 31 to 89% upon process optimization. Thus, the process has considerable potential for metal recovery and is environmentally beneficial.

Metal immobilization and phosphorus leaching after stabilization of pyrite ash contaminated soil by phosphate amendments.

Science.gov (United States)

Zupančič, Marija; Lavrič, Simona; Bukovec, Peter

2012-02-01

In this study we would like to show the importance of a holistic approach to evaluation of chemical stabilization using phosphate amendments. An extensive evaluation of metal stabilization in contaminated soil and an evaluation of the leaching of phosphorus induced after treatment were performed. The soil was highly contaminated with Cu (2894 mg kg(-1)), Zn (3884 mg kg(-1)), As (247 mg kg(-1)), Cd (12.6 mg kg(-1)) and Pb (3154 mg kg(-1)). To immobilize the metals, mixtures of soil with phosphate (from H(3)PO(4) and hydroxyapatite (HA) with varying ratios) were prepared with a constant Pb : P molar ratio of 1: 10. The acetic acid extractable concentration of Pb in the mixture with the highest amount of added phosphoric acid (n(H(3)PO(4)) : n(HA) = 3 : 1) was reduced to 1.9% (0.62 mg L(-1)) of the extractable Pb concentration in the untreated soil, but the content of water extractable phosphorus in the samples increased from 0.04 mg L(-1) in the untreated soil sample up to 14.3 mg L(-1) in the same n(H(3)PO(4)) : n(HA) = 3 : 1 mixture. The high increase in arsenic mobility was also observed after phosphate addition. The PBET test showed phosphate induced reduction in Pb bioavailability. In attempting to stabilize Pb in the soil with the minimum treatment-induced leaching of phosphorus, it was found that a mixture of soil with phosphate addition in the molar ratio of H(3)PO(4) : HA of 0.75 : 1 showed the most promising results, with an acetic acid extractable Pb concentration of 1.35 mg L(-1) and a water extractable phosphorus concentration of 1.76 mg L(-1). The time-dependent leaching characteristics of metals and phosphorus for this mixture were evaluated by a column experiment, where irrigation of the soil mixture with the average annual amount of precipitation in Slovenia (1000 mm) was simulated. The phosphorus concentration in the leachates decreased from 2.60 mg L(-1) at the beginning of irrigation to 1.00 mg L(-1) at the end.

Acid leaching of natural chrysotile asbestos to mesoporous silica fibers

Science.gov (United States)

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.

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

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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.

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

Science.gov (United States)

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

2016-01-01

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

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

Science.gov (United States)

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.

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

International Nuclear Information System (INIS)

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

Neutron activation analysis for noble metals in matte leach residues

International Nuclear Information System (INIS)

Hart, R.J.

1978-01-01

The development of the neutron activation analysis technique as a method for rapid and precise determinations of platinum group metals in matte leach residues depends on obtaining a method for effecting complete and homogeneous sample dilution. A simple method for solid dilution of metal samples is outlined in this study, which provided a basis for the accurate determination of all the noble metals by the Neutron Activation Analysis technique

Bioleaching of heavy metals from soil using fungal-organic acids : bench scale testing

Energy Technology Data Exchange (ETDEWEB)

Cathum, S.J.; Ousmanova, D.; Somers, A.; Punt, M. [SAIC Canada, Ottawa, ON (Canada); Brown, C.E. [Environment Canada, Ottawa, ON (Canada). Emergencies Engineering Division]|[Environment Canada, Ottawa, ON (Canada). Environmental Technology Centre

2006-07-01

The ability of fungi to solubilize metals from solid materials may present new opportunities in environmental remediation. This paper presented details of a bench scale experiment that evaluated the leaching of heavy metals from contaminated soil using in situ fungal-generated organic acids. Rice was used as the growing media for organic acid production by A. foetidus. The cultivated fungus was placed on large pieces of potato-dextrose agar (PDA) plates and suspended in 5 L of sterilized water. The cooked rice was inoculated by pouring the 5 L spore suspension over the rice layer. Soil was obtained from a soil pile impacted with heavy metals at a private industrial site and augmented with Pb-contaminated soil. A polyethylene tub was used with a drain pipe leading to a leachate vessel. Crushed stone was spread over the bottom of the tub to assist leachate drainage. Approximately 45 kg of the contaminated soil was spread evenly over the stone layer to a depth of 10 cm. The concentrated spore suspension was sprinkled over the rice. Each week the leachate collection vessel was removed from the bioleaching system and the fine soil particles were allowed to settle. A control was run using the contaminated soil and solid substrate without fungus. Growth of A. foetidus was observed in both control experiment and test experiment after a period of 35 days. The pH of the leachate was measured as the fungal growth progressed. The process was assessed using ICP Mass Spectroscopy and electron spectroscopy, which showed that approximately 65 g of heavy metals were mobilized from 45 kg of soil, and that the biological leaching process resulted in greater mobilization of heavy metals relative to the control experiment. It was concluded that organic acids generated by A. foetidus were capable of leaching heavy metals from the soil. 30 refs., 4 tabs., 15 figs.

Leaching of heavy metals from contaminated soils: An experimental and modeling study

NARCIS (Netherlands)

Dijkstra, J.J.; Meeussen, J.C.L.; Comans, R.N.J.

2004-01-01

In this paper, we characterize the leaching of heavy metals (Ni, Cu, Zn, Cd, and Pb) from eight contaminated soils over a wide range of pH (pH 0.4-12) using an original approach based on batch pH-static leaching experiments in combination with selective chemical extractions and geochemical modeling.

Comparison of natural organic acids and synthetic chelates at enhancing phytoextraction of metals from a multi-metal contaminated soil

International Nuclear Information System (INIS)

Clistenes do Nascimento, Williams A.; Amarasiriwardena, Dula; Xing, Baoshan

2006-01-01

Chemically assisted phytoremediation has been developing to induce accumulation of metals by high biomass plants. Synthetic chelates have shown high effectiveness to reach such a goal, but they pose serious drawbacks in field application due to the excessive amount of metals solubilized. We compared the performance of synthetic chelates with naturally occurring low molecular weight organic acids (LMWOA) in enhancing phytoextraction of metals by Indian mustard (Brassica juncea) from multi-metal contaminated soils. Gallic and citric acids were able to induce removal of Cd, Zn, Cu, and Ni from soil without increasing the leaching risk. Net removal of these metals caused by LMWOA can be as much as synthetic chelates. A major reason for this is the lower phytotoxicity of LMWOA. Furthermore, supplying appropriate mineral nutrients increased biomass and metal removal. - Organic acids can be as efficient as synthetic chelates for use in phytoextraction of multi-metal contaminated soils

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

OpenAIRE

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...

Novel Approach for Enhanced Scandium and Titanium Leaching Efficiency from Bauxite Residue with Suppressed Silica Gel Formation.

Science.gov (United States)

Alkan, Gözde; Yagmurlu, Bengi; Cakmakoglu, Seckin; Hertel, Tobias; Kaya, Şerif; Gronen, Lars; Stopic, Srecko; Friedrich, Bernd

2018-04-04

The need of light weight alloys for future transportation industry puts Sc and Ti under a sudden demand. While these metals can bring unique and desired properties to alloys, lack of reliable sources brought forth a supply problem which can be solved by valorization of the secondary resources. Bauxite residue (red mud), with considerable Ti and Sc content, is a promising resource for secure supply of these metals. Due to drawbacks of the direct leaching route from bauxite residue, such as silica gel formation and low selectivity towards these valuable metals, a novel leaching process based on oxidative leaching conditions, aiming more efficient and selective leaching but also considering environmental aspects via lower acid consumption, was investigated in this study. Combination of hydrogen peroxide (H 2 O 2 ) and sulfuric acid (H 2 SO 4 ) was utilized as the leaching solution, where various acid concentrations, solid-to-liquid ratios, leaching temperatures and times were examined in a comparative manner. Leaching with 2.5 M H 2 O 2 : 2.5 M H 2 SO 4 mixture at 90 °C for 30 min was observed to be the best leaching conditions with suppressed silica gel formation and the highest reported leaching efficiency with high S/L ratio for Sc and Ti; 68% and 91%; respectively.

Irradiation effect on leaching behavior and form of heavy metals in fly ash of municipal solid waste incinerator

International Nuclear Information System (INIS)

Nam, Sangchul; Namkoong, Wan

2012-01-01

Highlights: ► No research has been done to examine effect of electron beam irradiation on leaching behavior of heavy metals in fly ash. ► Electron beam irradiation on fly ash had significant effect on heavy metal leaching. ► Leaching potential of heavy metals in fly ash differed among metal species tested (Pb, Zn, Cu). ► Metal forms in the ash were analyzed to explain the difference. ► The difference could be explained by metal form change. - Abstract: Fly ash from a municipal solid waste incinerator (MSWI) is commonly classified as hazardous waste. High-energy electron beam irradiation systems have gained popularity recently as a clean and promising technology to remove environmental pollutants. Irradiation effects on leaching behavior and form of heavy metals in MSWI fly ash have not been investigated in any significant detail. An electron beam accelerator was used in this research. Electron beam irradiation on fly ash significantly increased the leaching potential of heavy metals from fly ash. The amount of absorbed dose and the metal species affected leaching behavior. When electron beam irradiation intensity increased gradually up to 210 kGy, concentration of Pb and Zn in the leachate increased linearly as absorbed dose increased, while that of Cu underwent no significant change. Concentration of Pb and Zn in the leachate increased up to 15.5% (10.7 mg/kg), and 35.6% (9.6 mg/kg) respectively. However, only 4.8% (0.3 mg/kg) increase was observed in the case of Cu. The results imply that irradiation has significant effect on the leaching behavior of heavy metals in fly ash, and the effect is quite different among the metal species tested in this study. A commonly used sequential extraction analysis which can classify a metal species into five forms was conducted to examine any change in metal form in the irradiated fly ash. Notable change in metal form in fly ash was observed when fly ash was irradiated. Change in Pb form was much greater than that of

Impact of spreading olive mill waste water on agricultural soils for leaching of metal micronutrients and cations.

Science.gov (United States)

Aharonov-Nadborny, R; Tsechansky, L; Raviv, M; Graber, E R

2017-07-01

Olive mill waste water (OMWW) is an acidic (pH 4-5), saline (EC ∼ 5-10 mS cm -1 ), blackish-red aqueous byproduct of the three phase olive oil production process, with a high chemical oxygen demand (COD) of up to 220,000 mg L -1 . OMWW is conventionally disposed of by uncontrolled dumping into the environment or by semi-controlled spreading on agricultural soils. It was hypothesized that spreading such liquids on agricultural soils could result in the release and mobilization of indigenous soil metals. The effect of OMWW spreading on leaching of metal cations (Na, K, Mg, Mn, Fe, Cu, Zn) was tested in four non-contaminated agricultural soils having different textures (sand, clay loam, clay, and loam) and chemical properties. While the OMWW contributed metals to the soil solution, it also mobilized indigenous soil metals as a function of soil clay content, cation exchange capacity (CEC), and soil pH-buffer capacity. Leaching of soil-originated metals from the sandy soil was substantially greater than from the loam and clay soils, while the clay loam was enriched with metals derived from the OMWW. These trends were attributed to cation exchange and organic-metal complex formation. The organic matter fraction of OMWW forms complexes with metal cations; these complexes may be mobile or precipitate, depending on the soil chemical and physical environment. Copyright © 2017 Elsevier Ltd. All rights reserved.

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

International Nuclear Information System (INIS)

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)

THE INFLUENCE OF SELECTED FACTORS ON THE LEACHING OF HEAVY METALS FROM SMELTER WASTE

Directory of Open Access Journals (Sweden)

Kamila Mizerna

2015-07-01

Full Text Available The paper presents the results of leaching research of selected heavy metals (Pb, Cu, Zn, Ni, Cd, Cr from industrial waste. The impact of waste fragmentation on the level of heavy metals leaching was analyzed. The decrease of copper and zinc release and the increase of nickel leaching were observed with increasing grain size fraction of waste. Furthermore, release of contaminants in different ratio of liquid to solid (L/S = 10 dm3/kg and 2 dm3/kg was studied. Higher concentrations of heavy metals were determined in ratio of L/S = 10 dm3/kg. In order to determine the risk of tested waste to the environment, the results were compared with the current law. This allowed the classification of the waste to hazardous waste.

Treatment of metallurgical wastes : recovery of metal values from smelter slags by pressure oxidative leaching

Energy Technology Data Exchange (ETDEWEB)

Li, Y.; Perederiy, I.; Papangelakis, V.G. [Toronto Univ., ON (Canada). Dept. of Chemical Engineering and Applied Chemistry

2008-07-01

Vast quantities of slag are produced and dumped as waste by-products during the production of base metals by smelting operations. These slags contain large amounts of valuable metals which lead to a decrease in metal yield and, combined with the entrapped sulphur, pose a danger to the environment. The dissolution of fayalite is important for the selective recovery of valuable metals and the cleanup of slags in high pressure oxidative leaching. The nature of base metals and iron in solidified slag must be investigated in order to understand the mechanism of the process. This paper discussed the application of powder X-ray diffraction (PXRD) and scanning electron microscopy (SEM) for the characterization of a smelter slag microstructure. The study used leaching tests with the same smelter slag to measure and monitor the results of leaching, including metal extraction levels, the extent of iron dissolution as well as impurity contents. The paper provided information on the experiment with particular reference to slag leaching, chemical analysis, and characterization. It was concluded that slag consists of several solid phases with base metal sulfide and oxide droplets entrapped in the fayalite matrix or silica regions. Therefore, nickel, copper, cobalt, and zinc need to be exposed either chemically or mechanically to promote their recovery. 21 refs., 4 tabs., 5 figs.

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

Energy Technology Data Exchange (ETDEWEB)

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

2014-02-15

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

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

International Nuclear Information System (INIS)

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

2014-01-01

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

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

Science.gov (United States)

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

2017-02-01

During the process of bioleaching, lead (Pb) recovery is low. This low recovery is caused by a problem with the bioleaching technique. This research investigated the bioleaching combination of bioleaching with brine leaching to remove heavy metals from lead-zinc mine tailings. The impact of different parameters were studied, including the effects of initial pH (1.5-3.0) and solid concentration (5-20%) for bioleaching, and the effects of sodium chloride (NaCl) concentration (10-200 g/L) and temperature (25 and 50 °C) for brine leaching. Complementary characterization experiments (Sequential extraction, X-ray diffractometer (XRD), scanning electronic microscope (SEM)) were also conducted to explore the transformation of tailings during the leaching process. The results showed that bioleaching efficiency was significantly influenced by initial pH and solid concentration. Approximately 85.45% of iron (Fe), 4.12% of Pb, and 97.85% of zinc (Zn) were recovered through bioleaching in optimum conditions. Increasing the brine concentration and temperature promoted lead recovery. Lead was recovered from the bioleaching residues at a rate of 94.70% at 25 °C and at a rate of 99.46% at 50 °C when the NaCl concentration was 150 g/L. The study showed that bioleaching significantly changed the speciation of heavy metals and the formation and surface morphology of tailings. The metals were mainly bound in stable fractions after bioleaching. Copyright © 2016 Elsevier Ltd. All rights reserved.

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

International Nuclear Information System (INIS)

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)

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

OpenAIRE

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...

Study of the leaching of heavy metals from waste water sludge and incinerator's ash, using coupled thermostated columns and DTPA as complex agent

International Nuclear Information System (INIS)

Vite T, J.; Vite T, M.; Guerrero D, J.; Carreno de Leon, M.C.

2000-01-01

We studied the metallic composition from waste water sludge and incinerators ashes of an incinerator located in Toluca, Mexico, the qualitative studies were made using the Activation Analysis technique, and fluorescence X-ray techniques. The quantitative analysis of heavy metals in the wastes were made using Inductively coupled plasma atomic emission spectrometry (Icp-Aes). For leaching the samples, we used four coupled thermostated columns, each one had a p H of 2,5, 7 and 10. The flux of the air was of 1600 cc/min. The temperature was maintain constant in 60 Centigrade using a thermostated system. For this study we used 100 g of wastes mixed with mineral acid or sodium hydroxide to reach p H 2,5,7 and 10. We added a reducing and tensoactive agents and finally DTPA as complex agent. With this method, we obtain a better leaching efficiency using a complex agent. However the high DTPA cost, make this process expansive that is why we recommend to work with another classes of complex agents, that be cheaper to leach metals of different chemistry matrix. (Author)

The leaching kinetics of cadmium from hazardous Cu-Cd zinc plant residues.

Science.gov (United States)

Li, Meng; Zheng, Shili; Liu, Biao; Du, Hao; Dreisinger, David Bruce; Tafaghodi, Leili; Zhang, Yi

2017-07-01

A large amount of Cu-Cd zinc plant residues (CZPR) are produced from the hydrometallurgical zinc plant operations. Since these residues contain substantial amount of heavy metals including Cd, Zn and Cu, therefore, they are considered as hazardous wastes. In order to realize decontamination treatment and efficient extraction of the valuable metals from the CZPR, a comprehensive recovery process using sulfuric acid as the leaching reagent and air as the oxidizing reagent has been proposed. The effect of temperature, sulfuric acid concentration, particle size, solid/liquid ratio and stirring speed on the cadmium extraction efficiency was investigated. The leaching kinetics of cadmium was also studied. It was concluded that the cadmium leaching process was controlled by the solid film diffusion process. Moreover, the order of the reaction rate constant versus H 2 SO 4 concentration, particle size, solid/liquid ratio and stirring speed was calculated. The XRD and SEM-EDS analysis results showed that the main phases of the secondary sulfuric acid leaching residues were lead sulfate and calcium sulfate. Copyright © 2017 Elsevier Ltd. All rights reserved.

Recovery of valuable metals from waste cathode materials of spent lithium-ion batteries using mild phosphoric acid

Energy Technology Data Exchange (ETDEWEB)

Chen, Xiangping, E-mail: chenxiangping101@163.com [School of Environmental Science and Engineering, Shaanxi University of Science & Technology, Xi’an 710021 (China); College of Chemistry and Chemical Engineering, Central South University, Changsha 410083 (China); Ma, Hongrui, E-mail: mahr@sust.edu.cn [School of Environmental Science and Engineering, Shaanxi University of Science & Technology, Xi’an 710021 (China); Luo, Chuanbao; Zhou, Tao [College of Chemistry and Chemical Engineering, Central South University, Changsha 410083 (China)

2017-03-15

Graphical abstract: Cobalt can be directly recovered as Co{sub 3}(PO{sub 4}){sub 2} from waste LiCoO{sub 2} using H{sub 3}PO{sub 4} as leaching and precipitating agent. - Highlights: • Phosphoric acid was innovatively used as leaching and precipitating agent. • Over 99% Co and Li can be separated and recovered in a single leaching step. • Co and Li can be separated under mild conditions of 40 °C and 0.7 M H{sub 3}PO{sub 4}. • Activation energy values for Co and Li are 7.3 and 10.168 kJ/mol. • Cobalt phosphate (97.1% in purity) can be obtained as the leaching product. - Abstract: Sustainable recycling of valuable metals from spent lithium-ion batteries (LIBs) may be necessary to alleviate the depletion of strategic metal resources and potential risk of environmental pollution. Herein a hydrometallurgical process was proposed to explore the possibility for the recovery of valuable metals from the cathode materials (LiCoO{sub 2}) of spent LIBs using phosphoric acid as both leaching and precipitating agent under mild leaching conditions. According to the leaching results, over 99% Co can be separated and recovered as Co{sub 3}(PO{sub 4}){sub 2} in a short-cut process involved merely with leaching and filtrating, under the optimized leaching conditions of 40 °C (T), 60 min (t), 4 vol.% H{sub 2}O{sub 2}, 20 mL g{sup −1} (L/S) and 0.7 mol/L H{sub 3}PO{sub 4}. Then leaching kinetics was investigated based on the logarithmic rate kinetics model and the obtained results indicate that the leaching of Co and Li fits well with this model and the activation energies (Ea) for Co and Li are 7.3 and 10.2 kJ/mol, respectively. Finally, it can be discovered from characterization results that the obtained product is 97.1% pure cobalt phosphate (Co{sub 3}(PO{sub 4}){sub 2}).

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

Science.gov (United States)

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.

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

Directory of Open Access Journals (Sweden)

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.

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

Science.gov (United States)

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.

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

Directory of Open Access Journals (Sweden)

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.

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

Science.gov (United States)

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.

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

Science.gov (United States)

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

2015-11-01

One concern for recycle and reuse of scrap tires is the leaching of tire constituents (organic and inorganic) with time, and their subsequent potential harmful impacts in environment. The main objective of this study was to examine the leaching of dissolved organic carbon (DOC), dissolved nitrogen (DN), and selected inorganic constituents from scrap tires. Different sizes of tire chips and crumb rubber were exposed to leaching solutions with pH's ranging from 3.0 to 10.0 for 28days. The leaching of DOC and DN were found to be higher for smaller size tire chips; however, the leaching of inorganic constituents was independent of the size. In general, basic pH conditions increased the leaching of DOC and DN, whereas acidic pH conditions led to elevated concentrations of metals. Leaching was minimal around the neutral pH values for all the monitored parameters. Analysis of the leaching rates showed that components associated with the rubbery portion of the tires (DOC, DN, zinc, calcium, magnesium, etc.) exhibited an initial rapid followed by a slow release. On the other hand, a constant rate of leaching was observed for iron and manganese, which are attributed to the metal wires present inside the tires. Although the total amounts that leached varied, the observed leaching rates were similar for all tire chip sizes and leaching solutions. Operation under neutral pH conditions, use of larger size tire chips, prewashing of tires, and removal of metal wires prior to application will reduce the impact of tire recycle and reuse. Copyright © 2015 Elsevier Ltd. All rights reserved.

The study of heavy metals leaching from waste foundry sands using a one-step extraction

Science.gov (United States)

Bożym, Marta

2017-10-01

There are a number of leaching test which are used to evaluate the effect of foundry waste disposal on the environment (TCLP, SPLP, ASTM at al.). Because the spent foundry sand are usually deposited at the ground level and they have a similar structure to the soil, survey mobility of metals using the same methods seems appropriate. One-step extraction allows for the evaluation of the mobility and bioavailability of metals in soil and waste. Waste foundry sands have been successfully used as a component in manufactured soils in U.S., but concern over metal contamination must be eliminated before considering this direction of use. The study evaluated the leaching of heavy metals (Cd, Pb, Cu, Zn, Cr, Ni) from deposited waste foundry sands. The overall, as well as heavy metals were extracted by different type of extractants: H2O, CH3COOH, HCl, EDTA, MgCl2 and NaCOOH. These extractants are most commonly used to study the mobility and bioavailability of metals in soil and waste. In the present study applicable standards and methodology described in the literature in analysis were used. The results allowed to evaluate the bioavailability of metals leached from those wastes.

The treatments of soil Rirang by floatation and Acid leaching

International Nuclear Information System (INIS)

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)

Waste acid/metal solution reduction and recovery by vacuum distillation

International Nuclear Information System (INIS)

Jones, E.O.; Wilcox, W.A.; Johnson, N.T.; Bowdish, F.W.

1995-01-01

Processes involving distillation under reduced pressure were developed at the Pacific Northwest Laboratory several years ago to recover spent acid solutions generated during the manufacture of nuclear fuel for the N-Reactor at the Hanford site. Following construction and testing of a pilot-plant, the technology was licensed to Viatec Recovery Systems, Inc. for commercialization. The technology developed included specialized distillation and rectification of volatile acids, removal of water and/or volatile acid from sulfuric acid, and precipitation of salts. A key feature of the Waste Acid Detoxification and Reclamation (WADR) technology is the development and use of advanced thermoplastic and fluoropolymer materials of construction in all critical process equipment. The technology was then expanded to include crystallization to recover metal salts for possible reuse. Economic and environmental advantages of the procedures include recovery of acids for reuse, simplification or elimination of the disposal of waste solutions, and possible recovery of metals. Industries expected to benefit from such applications include galvanizing, electroplating, sand leaching and any where metals are cleaned in acid solutions. Currently a modular system has been assembled for recovery of several different spent acid solutions

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

Science.gov (United States)

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

2014-02-01

Electronic waste has been increasing proportionally with the technology. So, nowadays, it is necessary to consider the useful life, recycling, and final disposal of these equipment. Metals, such as Au, Ag, Cu, Sn and Ni can be found in the printed circuit boards (PCB). According to this, the aims of this work is to characterize the PCBs of mobile phones with aqua regia; obtaining "reference" values of leaching, to gold and silver, with cyanide and nitric acid, respectively; and study the process of leaching of these metals in alternative leaching with sodium thiosulfate and ammonium thiosulfate. The metals were characterized by digesting the sample with aqua regia for 1 and 2h at 60°C and 80°C. The leaching of Au with a commercial reagent (cyanide) and the Ag with HNO3were made. The leaching of Au and Ag with alternative reagents: Na2S2O3, and (NH4)2S2O3 in 0.1M concentration with the addition of CuSO4, NH4OH, and H2O2, was also studied. The results show that the digestion with aqua regia was efficient to characterize the metals present in the PCBs of mobile phones. However, the best method to solubilize silver was by digesting the sample with nitric acid. The leaching process using sodium thiosulfate was more efficient when an additional concentration of 0.015 and 0.030 M of the CuSO4 was added. Copyright © 2013 Elsevier Ltd. All rights reserved.

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

Science.gov (United States)

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

2014-04-30

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

Extraction of heavy metals from MSWI fly ash using hydrochloric acid and sodium chloride solution.

Science.gov (United States)

Weibel, Gisela; Eggenberger, Urs; Kulik, Dmitrii A; Hummel, Wolfgang; Schlumberger, Stefan; Klink, Waldemar; Fisch, Martin; Mäder, Urs K

2018-03-17

Fly ash from municipal solid waste incineration contains a large potential for recyclable metals such as Zn, Pb, Cu and Cd. The Swiss Waste Ordinance prescribes the treatment of fly ash and recovery of metals to be implemented by 2021. More than 60% of the fly ash in Switzerland is acid leached according to the FLUWA process, which provides the basis for metal recovery. The investigation and optimization of the FLUWA process is of increasing interest and an industrial solution for direct metal recovery within Switzerland is in development. With this work, a detailed laboratory study on different filter cakes from fly ash leaching using HCl 5% (represents the FLUWA process) and concentrated sodium chloride solution (300 g/L) is described. This two-step leaching of fly ash is an efficient combination for the mobilization of a high percentage of heavy metals from fly ash (Pb, Cd ≥ 90% and Cu, Zn 70-80%). The depletion of these metals is mainly due to a combination of redox reaction and metal-chloride-complex formation. The results indicate a way forward for an improved metal depletion and recovery from fly ash that has potential for application at industrial scale. Copyright © 2018 Elsevier Ltd. All rights reserved.

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

Directory of Open Access Journals (Sweden)

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.

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

Science.gov (United States)

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.

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

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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.

Leaching Behavior of Selected Trace and Toxic Metals in Coal Fly Ash Samples Collected from Two Thermal Power Plants, India.

Science.gov (United States)

Sandeep, P; Sahu, S K; Kothai, P; Pandit, G G

2016-09-01

Studies on leaching behavior of metals associated with coal fly ash (FA) are of great concern because of possible contamination of the aquatic environment. In the present study, leaching behavior of metals (As, Se, Cr, Pb, V, Zn, etc.) in two different FA samples (FA1 and FA2) was investigated at various pH (2-12), temperatures of leachate solution and using TCLP. At pH 2, the highest leaching was observed for Fe (21.6 and 32.8 µg/g), whereas at pH 12, Arsenic was found to have the highest leaching (1.5 and 2.4 µg/g) in FA1 and FA2. Leachate solution temperature showed a positive effect on the metal's leachability. In TCLP, most of the metal's leachability was observed to be higher than that of batch leaching tests. The present study suggests that, leaching of As and Se from FA samples can moderately affect ground/surface water quality at the study locations.

Effects of aerobic and anaerobic biological processes on leaching of heavy metals from soil amended with sewage sludge compost.

Science.gov (United States)

Fang, Wen; Wei, Yonghong; Liu, Jianguo; Kosson, David S; van der Sloot, Hans A; Zhang, Peng

2016-12-01

The risk from leaching of heavy metals is a major factor hindering land application of sewage sludge compost (SSC). Understanding the change in heavy metal leaching resulting from soil biological processes provides important information for assessing long-term behavior of heavy metals in the compost amended soil. In this paper, 180days aerobic incubation and 240days anaerobic incubation were conducted to investigate the effects of the aerobic and anaerobic biological processes on heavy metal leaching from soil amended with SSC, combined with chemical speciation modeling. Results showed that leaching concentrations of heavy metals at natural pH were similar before and after biological process. However, the major processes controlling heavy metals were influenced by the decrease of DOC with organic matter mineralization during biological processes. Mineralization of organic matter lowered the contribution of DOC-complexation to Ni and Zn leaching. Besides, the reducing condition produced by biological processes, particularly by the anaerobic biological process, resulted in the loss of sorption sites for As on Fe hydroxide, which increased the potential risk of As release at alkaline pH. Copyright © 2016 Elsevier Ltd. All rights reserved.

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

Science.gov (United States)

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

2016-01-01

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

British strong-acid leach process targeted at refractory uranium ores

International Nuclear Information System (INIS)

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.)

Leach tests on grouts made with actual and trace metal-spiked synthetic phosphate/sulfate waste

International Nuclear Information System (INIS)

Serne, R.J.; Martin, W.J.; LeGore, V.L.; Lindenmeier, C.W.; McLaurine, S.B.; Martin, P.F.C.; Lokken, R.O.

1989-10-01

Pacific Northwest Laboratory conducted experiments to produce empirical leach rate data for phosphate-sulfate waste (PSW) grout. Effective diffusivities were measured for various radionuclides ( 90 Sr, 99 Tc, 14 C, 129 I, 137 Cs, 60 Co, 54 Mn, and U), stable major components (NO 3 - , SO 4 2- , H 3 BO 3 , K and Na) and the trace constituents Ag, As, Cd, Hg, Pb, and Se. Two types of leach tests were used on samples of actual PSW grout and synthetic PSW grout: the American Nuclear Society (ANS) 16.1 intermittent replacement leach test and a static leach test. Grout produced from both synthetic and real PSW showed low leach rates for the trace metal constituents and most of the waste radionuclides. Many of the spiked trace metals and radionuclides were not detected in any leachates. None of the effluents contained measurable quantities of 137 Cs, 60 Co, 54 Mn, 109 Cd, 51 Cr, 210 Pb, 203 Hg, or As. For those trace species with detectable leach rates, 125 I appeared to have the greatest leach rate, followed by 99 Tc, 75 Se, and finally U, 14 C, and 110m Ag. Leach rates for nitrate are between those for I and Tc, but there is much scatter in the nitrate data because of the very low nitrate inventory. 32 refs., 6 figs., 15 tabs

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

Science.gov (United States)

Tang, Jinfeng; Steenari, Britt-Marie

2016-02-01

Ash from municipal solid waste incineration (MSWI) may be quite cumbersome to handle. Some ash fractions contain organic pollutants, such as dioxins, as well as toxic metals. Additionally, some of the metals have a high value and are considered as critical to the industry. Recovery of copper, zinc and lead from MSWI ashes, for example, will not only provide valuable metals that would otherwise be landfilled but also give an ash residue with lower concentrations of toxic metals. In this work, fly ash and bottom ash from an MSWI facility was used for the study and optimization of metal leaching using different solutions (nitric acid, hydrochloric acid and sulfuric acid) and parameters (temperature, controlled pH value, leaching time, and liquid/solid ratio). It was found that hydrochloric acid is relatively efficient in solubilizing copper (68.2±6.3%) and zinc (80.8±5.3%) from the fly ash in less than 24h at 20°C. Efficient leaching of cadmium and lead (over 92% and 90% respectively) was also achieved. Bottom ash from the same combustion unit was also characterized and leached using acid. The metal yields were moderate and the leachates had a tendency to form a gelatinous precipitate, which indicates that the solutions were actually over-saturated with respect to some components. This gel formation will cause problems for further metal purification processes, e.g. solvent extraction. Copyright © 2015 Elsevier Ltd. All rights reserved.

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

Science.gov (United States)

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

2016-06-01

Each year a tremendous volume of V-Ni rich ashes is produced by fuel oil consuming power plants throughout the world. Recovery of precious metals existing in these ashes is very important from both economic and environmental aspects. The present research was aimed at investigating bioleaching potential of Penicillium simplicissimum for the recovery of metals from power plant residual ash (PPR ash) using different bioleaching methods such as one-step, two-step, and spent-medium bioleaching at 1% (w/v) pulp density. Furthermore, the effects of thermal pretreatment on leaching of V, Ni, and Fe, as major elements present in PPR ash, were studied. Thermal pretreatment at various temperatures removed the carbonaceous and volatile fraction of the ash and affected the fungal growth and metal leachability. The highest extraction yields of V and Ni were achieved for the original PPR ash, using spent-medium bioleaching in which nearly 100% of V and 40% of Ni were extracted. The maximum extraction yield of Fe (48.3%) was obtained for the pretreated PPR ash at 400°C by spent-medium bioleaching. In addition, the fungal growth in pure culture was investigated through measurement of produced organic acids via high performance liquid chromatography (HPLC). Chemical leaching experiments were performed, using commercial organic acids at the same concentrations as those produced under optimum condition of fungal growth (5237ppm citric, 3666ppm gluconic, 1287ppm oxalic and 188ppm malic acid). It was found that in comparison to chemical leaching, bioleaching improved V and Ni recovery up to 19% and 12%, respectively. Moreover, changes in physical and chemical properties as well as morphology of the samples utilizing appropriate analytical methods such as XRF, XRD, FTIR, and FE-SEM were comprehensively investigated. Copyright © 2016 Elsevier Ltd. All rights reserved.

The study of heavy metals leaching from waste foundry sands using a one-step extraction

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Bożym Marta

2017-01-01

Full Text Available There are a number of leaching test which are used to evaluate the effect of foundry waste disposal on the environment (TCLP, SPLP, ASTM at al.. Because the spent foundry sand are usually deposited at the ground level and they have a similar structure to the soil, survey mobility of metals using the same methods seems appropriate. One-step extraction allows for the evaluation of the mobility and bioavailability of metals in soil and waste. Waste foundry sands have been successfully used as a component in manufactured soils in U.S., but concern over metal contamination must be eliminated before considering this direction of use. The study evaluated the leaching of heavy metals (Cd, Pb, Cu, Zn, Cr, Ni from deposited waste foundry sands. The overall, as well as heavy metals were extracted by different type of extractants: H2O, CH3COOH, HCl, EDTA, MgCl2 and NaCOOH. These extractants are most commonly used to study the mobility and bioavailability of metals in soil and waste. In the present study applicable standards and methodology described in the literature in analysis were used. The results allowed to evaluate the bioavailability of metals leached from those wastes.

Leaching assessment of radioactive and non-radioactive elements from Brazilian phosphogypsum

International Nuclear Information System (INIS)

Silva, N.C.; De Nadai Fernandes, E.A.; Cipriani, M.; Taddei, M.H.T.

2002-01-01

Phosphogypsum is a high volume by-product from phosphoric acid industries. Due to presence of certain impurities, mainly naturally-occurring radionuclides, this material has restriction for its use as building material and soil amendment. Then, phosphogypsum currently produced has been stacked near industries. To obtain more detailed information about the physico-chemical availability of heavy metals and radionuclides (Al, Ba, Cr, Fe, Mn, Th, U, Zn, Ra-226, Ra-228, Pb-210) in Brazilian phosphogypsum, three leaching procedures (sequential extraction, toxicity characteristic leaching procedure and soil fertility) were applied in samples from two phosphoric acid industries. Results indicated that the major fraction of heavy metals and radionuclides is associated with phosphogypsum lattice structure. (author)

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

International Nuclear Information System (INIS)

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

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

International Nuclear Information System (INIS)

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

Microbiological Leaching; an Environmentally Friendly and Cost Effective Method for Extraction of Metals

Directory of Open Access Journals (Sweden)

Ghobeiti-Hasab Mehdi

2018-02-01

Full Text Available Finding a cleaner, environmentally friendly and cost-effective way of metal and mineral extraction has a great importance in today’s world. Using microorganisms in bio-leaching and bio-oxidation process is of great value. From Archaea to bacteria and fungi, microorganisms can play an important role in extraction of metals from mine drainage and un-accessible sources, both in aquatic and terrestrial environments. Optimization of environmental factors such as the temperature, pH and substrate concentration is crucially important to access the optimum extraction of selected metals from an ore or mine drainage. The present paper will review the bio-leaching and bio-oxidation process of minerals with emphasis on the most well-known species of bacterial communities of such ability, through the literature.

In situ leaching of uranium

International Nuclear Information System (INIS)

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)

Lead, cadmium and cobalt (Pb, Cd, and Co) leaching of glass-clay containers by pH effect of food.

Science.gov (United States)

Valadez-Vega, Carmen; Zúñiga-Pérez, Clara; Quintanar-Gómez, Samuel; Morales-González, José A; Madrigal-Santillán, Eduardo; Villagómez-Ibarra, José Roberto; Sumaya-Martínez, María Teresa; García-Paredes, Juan Diego

2011-01-01

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

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

Directory of Open Access Journals (Sweden)

Juan Diego García-Paredes

2011-04-01

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

Effect of organic acids produced by penicillium notatum on the extraction of metals ions from brown shale

International Nuclear Information System (INIS)

Bhatti, H.N.; Sarwar, S.; Ilyas, S.

2012-01-01

Preset study was undertaken to check the bio leaching feasibility of brown shale with Penicillium notatum by using different carbon sources. Large quantities of the metal ions are embodied in shales that can be recovered. Presently available techniques (pyrometallurgical and hydrometallurgical) are expensive or may have a negative impact on the environment. Penicillium notatum exhibited a good potential in generating varieties of organic acids effective for metal ions solubilization. Maximum leaching of Cu (91.55 %) and Mg (79.83 %) was obtained with glucose as substrate while maximum recovery of Mn (71.46 %) was obtained in medium having molasses as substrate. (author)

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

International Nuclear Information System (INIS)

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)

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

International Nuclear Information System (INIS)

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

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

Science.gov (United States)

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.

Behaviour of metalloids and metals from highly polluted soil samples when mobilized by water – Evaluation of static versus dynamic leaching

International Nuclear Information System (INIS)

Wennrich, Rainer; Daus, Birgit; Müller, Karsten; Stärk, Hans-Joachim; Brüggemann, Lutz; Morgenstern, Peter

2012-01-01

The mobilization behaviour of metalloids and metals when leached by water from highly polluted soil/sediment samples was studied using static and dynamic approaches employing batch methodology and rotating coiled columns (RCC), respectively. Increasing the solution-to-solid ratios during batch leaching resulted in different enhanced mobilization rates, which are element-specific and matrix-specific. When dynamic leaching is employed with continuous replacement of the eluent, a higher portion is mobilized than when using batch elution with an identical solid-to-water ratio. Using RCC the time-resolved leaching of the elements was monitored to demonstrate the leaching patterns. For the majority of elements a significant decrease could be shown in the mobilized portion of the elements with ongoing leaching process. The data were discussed targeted at solid liquid partitioning coefficients of the metal(loid)s. The capabilities in application of K d values was demonstrated for dynamic leaching which is relevant for environmental processes. - Highlights: ► We examine the mobilization of metal(loid)s by water under simulated conditions. ► Static versus dynamic leaching (RCC) with continuous supply of extractant was compared. ► RCC is favourable for detailed time-resolved investigations of the leaching behaviour. ► The influence of matrices on the leaching behaviour was investigated. ► The capabilities of the K d values in environmentally relevant processes is shown. - Dynamic leaching with continuous supply of water has proved as tool for long-term and time-resolved mobility of metal(loid)s in contaminated soils.

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

Energy Technology Data Exchange (ETDEWEB)

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.

Microbial ecology of Rum Jungle, III. Leaching behaviour of sulphidic waste material under controlled conditions

International Nuclear Information System (INIS)

Babij, T.; Goodman, A.; Khalid, A.M.; Ralph, B.J.

1981-12-01

The discharge, into river systems, of acid and heavy metals generated by leaching of sulphidic waste materials at the abandoned opencut uranium mine at Rum Jungle, Northern Territory, is causing continuing pollution of the surrounding environment. The maximum effects of acid and microorganisms on samples from the overburden dump material, under defined and controlled environmental conditions, were assessed using reactor systems. These samples came from the overburden dump resulting from the mining of White's orebody. Similarly, the stability of tailings material under conditions of flooding and increasing acidity was determined. At ph 2.5, metals in White's dump material were solubilised by acid attack only, whereas at pH 3.5, bacterial activity (principally that of Thiobacillus ferrooxidans) generated acidity and contributed significantly to metal release. Under microaerophilic conditions Thiobacillus ferrooxidans continued to effect metal release from the ore, but did not produce further acidity. If White's overburden is returned to the acidic, flooded opencuts, complete solubilisation of the material will occur. The exclusion of oxygen from the dump will not necessarily stop bacterially catalysed leaching processes. Under highly aerated and agitated flooded conditions the tailings material was not active, except for copper release of about 2 g kg -1 ore at pH 4.0. The only deleterious element released by increasing acidity was copper, which was 100 per cent solubilised at pH 2.5. Uranium was always lss than 3 μg kg -1 ore, and lead was detected only at pH 2.5. Indigenous leaching bacteria did not develop

Leaching for recovery of copper from municipal solid waste incineration fly ash: influence of ash properties and metal speciation.

Science.gov (United States)

Lassesson, Henric; Fedje, Karin Karlfeldt; Steenari, Britt-Marie

2014-08-01

Recovery of metals occurring in significant amounts in municipal solid waste incineration fly ash, such as copper, could offer several advantages: a decreased amount of potentially mobile metal compounds going to landfill, saving of natural resources and a monetary value. A combination of leaching and solvent extraction may constitute a feasible recovery path for metals from municipal solid waste incineration fly ash. However, it has been shown that the initial dissolution and leaching is a limiting step in such a recovery process. The work described in this article was focused on elucidating physical and chemical differences between two ash samples with the aim of explaining the differences in copper release from these samples in two leaching methods. The results showed that the chemical speciation is an important factor affecting the release of copper. The occurrence of copper as phosphate or silicate will hinder leaching, while sulphate and chloride will facilitate leaching. © The Author(s) 2014.

Leaching Studies for Copper and Solder Alloy Recovery from Shredded Particles of Waste Printed Circuit Boards

Science.gov (United States)

Kavousi, Maryam; Sattari, Anahita; Alamdari, Eskandar Keshavarz; Fatmehsari, Davoud Haghshenas

2018-03-01

Printed circuit boards (PCBs) comprise various metals such as Cu, Sn, and Pb, as well as platinum group metals. The recovery of metals from PCBs is important not only due to the waste treatment but also for recycling of valuable metals. In the present work, the leaching process of Cu, Sn, and Pb from PCBs was studied using fluoroboric acid and hydrogen peroxide as the leaching agent and oxidant, respectively. Pertinent factors including concentration of acid, temperature, liquid-solid ratio, and concentration of oxidizing agent were evaluated. The results showed 99 pct of copper and 90 pct solder alloy were dissolved at a temperature of 298 K (25 °C) for 180 minutes using 0.6 M HBF4 for the particle size range of 0.15 to 0.4 mm. Moreover, solid/liquid ratio had insignificant effect on the recovery of metals. Kinetics analysis revealed that the chemical control regime governs the process with activation energy 41.25 and 38.9 kJ/mol for copper and lead leaching reactions, respectively.

Leaching Studies for Copper and Solder Alloy Recovery from Shredded Particles of Waste Printed Circuit Boards

Science.gov (United States)

Kavousi, Maryam; Sattari, Anahita; Alamdari, Eskandar Keshavarz; Fatmehsari, Davoud Haghshenas

2018-06-01

Printed circuit boards (PCBs) comprise various metals such as Cu, Sn, and Pb, as well as platinum group metals. The recovery of metals from PCBs is important not only due to the waste treatment but also for recycling of valuable metals. In the present work, the leaching process of Cu, Sn, and Pb from PCBs was studied using fluoroboric acid and hydrogen peroxide as the leaching agent and oxidant, respectively. Pertinent factors including concentration of acid, temperature, liquid-solid ratio, and concentration of oxidizing agent were evaluated. The results showed 99 pct of copper and 90 pct solder alloy were dissolved at a temperature of 298 K (25 °C) for 180 minutes using 0.6 M HBF4 for the particle size range of 0.15 to 0.4 mm. Moreover, solid/liquid ratio had insignificant effect on the recovery of metals. Kinetics analysis revealed that the chemical control regime governs the process with activation energy 41.25 and 38.9 kJ/mol for copper and lead leaching reactions, respectively.

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

International Nuclear Information System (INIS)

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)

Economic metal recovery from fly ash

Energy Technology Data Exchange (ETDEWEB)

Gilliam, T.M.; Canon, R.M.; Egan, B.Z.; Kelmers, A.D.; Seeley, F.G.; Watson, J.S.

1982-08-01

Results are presented to show that fly ash can be an economical source of Al/sub 2/O/sub 3/, Fe/sub 2/O/sub 3/ and several other metals. Two processes are examined in detail, the direct acid leach of ash with hydrochloric acid and a pressure digestion-acid leach method. An economic evaluation is presented for each process, and direct acid leaching is considered the most attractive process. The benefits derived from using such a process are discussed. (15 refs.)

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

International Nuclear Information System (INIS)

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

Recovery Process of Li, Al and Si from Lepidolite by Leaching with HF

Directory of Open Access Journals (Sweden)

Gustavo D. Rosales

2017-03-01

Full Text Available This work describes the development of a new process for the recovery of Li, Al and Si along with the proposal of a flow sheet for the precipitation of those metals. The developed process is comprised of lepidolite acid digestion with hydrofluoric acid, and the subsequent precipitation of the metals present in the leach liquor. The leaching operational parameters studied were: reaction time, temperature and HF concentration. The experimental results indicate that the optimal conditions to achieve a Li extraction higher than 90% were: solid-liquid ratio, 1.82% (w/v; temperature, 123 °C; HF concentration, 7% (v/v; stirring speed, 330 rpm; and reaction time, 120 min. Al and Si can be recovered as Na3AlF6 and K2SiF6. LiF was separated from the leach liquor during water evaporation, with recovery values of 92%.

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

International Nuclear Information System (INIS)

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)

Chemical associations and mobilization of heavy metals in fly ash from municipal solid waste incineration.

Science.gov (United States)

Weibel, Gisela; Eggenberger, Urs; Schlumberger, Stefan; Mäder, Urs K

2017-04-01

This study focusses on chemical and mineralogical characterization of fly ash and leached filter cake and on the determination of parameters influencing metal mobilization by leaching. Three different leaching processes of fly ash from municipal solid waste incineration (MSWI) plants in Switzerland comprise neutral, acidic and optimized acidic (+ oxidizing agent) fly ash leaching have been investigated. Fly ash is characterized by refractory particles (Al-foil, unburnt carbon, quartz, feldspar) and newly formed high-temperature phases (glass, gehlenite, wollastonite) surrounded by characteristic dust rims. Metals are carried along with the flue gas (Fe-oxides, brass) and are enriched in mineral aggregates (quartz, feldspar, wollastonite, glass) or vaporized and condensed as chlorides or sulphates. Parameters controlling the mobilization of neutral and acidic fly ash leaching are pH and redox conditions, liquid to solid ratio, extraction time and temperature. Almost no depletion for Zn, Pb, Cu and Cd is achieved by performing neutral leaching. Acidic fly ash leaching results in depletion factors of 40% for Zn, 53% for Cd, 8% for Pb and 6% for Cu. The extraction of Pb and Cu are mainly limited due to a cementation process and the formation of a PbCu 0 -alloy-phase and to a minor degree due to secondary precipitation (PbCl 2 ). The addition of hydrogen peroxide during acidic fly ash leaching (optimized acidic leaching) prevents this reduction through oxidation of metallic components and thus significantly higher depletion factors for Pb (57%), Cu (30%) and Cd (92%) are achieved. The elevated metal depletion using acidic leaching in combination with hydrogen peroxide justifies the extra effort not only by reduced metal loads to the environment but also by reduced deposition costs. Copyright © 2016 Elsevier Ltd. All rights reserved.

Leaching of basic oxygen furnace sludge with sulphuric acid

Directory of Open Access Journals (Sweden)

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.

Biocatalytic and chemical leaching of a low-grade nickel laterite ore

Science.gov (United States)

Ciftci, Hasan; Atik, Suleyman; Gurbuz, Fatma

2018-04-01

Nickel and cobalt recovery from a low-grade nickel laterite ore, supplied from Çaldağ deposit (Manisa, Turkey) were investigated by bio and chemical leaching processes. The fungus, Aspergillus niger was used for biocatalytic leaching experiments. The effects of parameters (solid ratio and sucrose concentration) on the biocatalytic leaching of the ore were initially tested in flasks to obtain the optimum conditions for the A. niger. Then chemical leaching was applied as a comparison to bioleaching, using organic acids (citric, oxalic, acetic and gluconic acids) as well as a mixture of acids. According the results, the maximum dissolution yield of nickel, cobalt and iron were detected respectively as 95.3%, 74.3% and 50.0% by biocatalytic processes which containing 25% (w/v) sucrose and 1% (w/v) solids. The increase in the solid ratio adversely influenced the biocatalytic activity of A. niger. Finally, further tests in reactors (v = 1 and 10 L) were performed using the optimum conditions from the flask tests. The difference in metals recovery between biocatalytic and chemical leaching was significantly important. Bioleaching produced higher Ni and Co extractions (34.3-75.6%) than chemical process.

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

International Nuclear Information System (INIS)

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.)

Leaching behavior of mineral processing waste: Comparison of batch and column investigations

Energy Technology Data Exchange (ETDEWEB)

Al-Abed, Souhail R. [National Risk Management Research Laboratory, U.S. Environmental Protection Agency, 26 West Martin Luther King Drive, Cincinnati, OH 45268 (United States)], E-mail: al-abed.souhail@epa.gov; Jegadeesan, G. [Pegasus Technical Services Inc., 46 East Hollister Street, Cincinnati, OH 45219 (United States); Purandare, J. [Englandgeosystem Inc., 15375 Barranca Pkwy, Suite F-106, Irvine, CA 92618 (United States); Allen, D. [National Risk Management Research Laboratory, U.S. Environmental Protection Agency, 26 West Martin Luther King Drive, Cincinnati, OH 45268 (United States)

2008-05-30

In this study, a comparison of laboratory batch and column experiments on metal release profile from a mineral processing waste (MPW) is presented. Batch (equilibrium) and column (dynamic) leaching tests were conducted on ground MPW at different liquid-solid ratios (LS) to determine the mechanisms controlling metal release. Additionally, the effect of pH on metal release is also discussed. It was observed that acidic pH conditions induced dissolution of As, Zn and Cu. Negligible leaching at alkaline pH was observed. However, Se depicted amphoteric behavior with high release at low and high pH. The batch and column data showed that As and Se release increased with LS ratio, while that of Cu and Zn increased initially and tapered towards equilibrium values at high LS ratios. The results on metal release from the MPW suggested that dissolution of the metal was the controlling mechanism. Leaching profiles from the batch and column data corresponded well for most LS ratios. This is most likely due to the acidic character of the waste, minimal changes in pH during the column operation and granular structure of the waste. From a waste management perspective, low cost batch equilibrium studies in lieu of high cost column experiments can be used for decision making on its disposal only when the waste exhibits characteristics similar to the mineral processing waste.

Leaching behavior of mineral processing waste: Comparison of batch and column investigations

International Nuclear Information System (INIS)

Al-Abed, Souhail R.; Jegadeesan, G.; Purandare, J.; Allen, D.

2008-01-01

In this study, a comparison of laboratory batch and column experiments on metal release profile from a mineral processing waste (MPW) is presented. Batch (equilibrium) and column (dynamic) leaching tests were conducted on ground MPW at different liquid-solid ratios (LS) to determine the mechanisms controlling metal release. Additionally, the effect of pH on metal release is also discussed. It was observed that acidic pH conditions induced dissolution of As, Zn and Cu. Negligible leaching at alkaline pH was observed. However, Se depicted amphoteric behavior with high release at low and high pH. The batch and column data showed that As and Se release increased with LS ratio, while that of Cu and Zn increased initially and tapered towards equilibrium values at high LS ratios. The results on metal release from the MPW suggested that dissolution of the metal was the controlling mechanism. Leaching profiles from the batch and column data corresponded well for most LS ratios. This is most likely due to the acidic character of the waste, minimal changes in pH during the column operation and granular structure of the waste. From a waste management perspective, low cost batch equilibrium studies in lieu of high cost column experiments can be used for decision making on its disposal only when the waste exhibits characteristics similar to the mineral processing waste

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

Science.gov (United States)

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.

Selective extraction and recovery of rare earth metals from phosphor powders in waste fluorescent lamps using an ionic liquid system

International Nuclear Information System (INIS)

Yang, Fan; Kubota, Fukiko; Baba, Yuzo; Kamiya, Noriho; Goto, Masahiro

2013-01-01

Highlights: • Recycling of rare earth metals from fluorescent lamps was conducted by ionic liquid-mediated extraction. • Acid leaching from a waste phosphor powder was carried out using sulfuric and nitric acids. • An ionic liquid was used as extracting solvent for the rare earth metals. • Selective extraction of rare earth metals from leach solutions was attained. •The extracting ionic liquid phase was recyclable in the recovery process. -- Abstract: The recycling of rare earth metals from phosphor powders in waste fluorescent lamps by solvent extraction using ionic liquids was studied. Acid leaching of rare earth metals from the waste phosphor powder was examined first. Yttrium (Y) and europium (Eu) dissolved readily in the acid solution; however, the leaching of other rare earth metals required substantial energy input. Ionization of target rare earth metals from the waste phosphor powders into the leach solution was critical for their successful recovery. As a high temperature was required for the complete leaching of all rare earth metals, ionic liquids, for which vapor pressure is negligible, were used as an alternative extracting phase to the conventional organic diluent. An extractant, N, N-dioctyldiglycol amic acid (DODGAA), which was recently developed, showed a high affinity for rare earth metal ions in liquid–liquid extraction although a conventional commercial phosphonic extractant did not. An effective recovery of the rare earth metals, Y, Eu, La and Ce, from the metal impurities, Fe, Al and Zn, was achieved from the acidic leach solution of phosphor powders using an ionic liquid containing DODGAA as novel extractant system

Selective extraction and recovery of rare earth metals from phosphor powders in waste fluorescent lamps using an ionic liquid system

Energy Technology Data Exchange (ETDEWEB)

Yang, Fan; Kubota, Fukiko; Baba, Yuzo [Department of Applied Chemistry, Graduate School of Engineering, Kyushu University, 744 Motooka, Fukuoka 819-0395 (Japan); Kamiya, Noriho [Department of Applied Chemistry, Graduate School of Engineering, Kyushu University, 744 Motooka, Fukuoka 819-0395 (Japan); Center for Future Chemistry, Kyushu University, 744 Motooka, Fukuoka 819-0395 (Japan); Goto, Masahiro, E-mail: m-goto@mail.cstm.kyushu-u.ac.jp [Department of Applied Chemistry, Graduate School of Engineering, Kyushu University, 744 Motooka, Fukuoka 819-0395 (Japan); Center for Future Chemistry, Kyushu University, 744 Motooka, Fukuoka 819-0395 (Japan)

2013-06-15

Highlights: • Recycling of rare earth metals from fluorescent lamps was conducted by ionic liquid-mediated extraction. • Acid leaching from a waste phosphor powder was carried out using sulfuric and nitric acids. • An ionic liquid was used as extracting solvent for the rare earth metals. • Selective extraction of rare earth metals from leach solutions was attained. •The extracting ionic liquid phase was recyclable in the recovery process. -- Abstract: The recycling of rare earth metals from phosphor powders in waste fluorescent lamps by solvent extraction using ionic liquids was studied. Acid leaching of rare earth metals from the waste phosphor powder was examined first. Yttrium (Y) and europium (Eu) dissolved readily in the acid solution; however, the leaching of other rare earth metals required substantial energy input. Ionization of target rare earth metals from the waste phosphor powders into the leach solution was critical for their successful recovery. As a high temperature was required for the complete leaching of all rare earth metals, ionic liquids, for which vapor pressure is negligible, were used as an alternative extracting phase to the conventional organic diluent. An extractant, N, N-dioctyldiglycol amic acid (DODGAA), which was recently developed, showed a high affinity for rare earth metal ions in liquid–liquid extraction although a conventional commercial phosphonic extractant did not. An effective recovery of the rare earth metals, Y, Eu, La and Ce, from the metal impurities, Fe, Al and Zn, was achieved from the acidic leach solution of phosphor powders using an ionic liquid containing DODGAA as novel extractant system.

The leaching characteristics of vitrified slag

International Nuclear Information System (INIS)

Zhang, Jinlong; Li, Yaojian; Tian, Junguo; Sheng, Hongzhi; Xu, Yongxiang

2010-01-01

Full Text: Plasma-arc technology was developed to fix the heavy metal of flying ash by the Institute of Mechanics, Chinese Academy of Sciences (CAS-IMECH). A direct current (DC) experimental facility of 30 kW with plasma-arc technology was setup to form vitrified slag. The additives (CaO, SiO 2 ) were added into the reactor to form vitrified slag and fix the heavy metal (Cr, Pb), under dissimilar condition (long and short heating-up time, natural and water cooling). Vitrified slag was broken into different particle size, from 0.1 mm to 1 cm. The particles with different specific surface area were used to study the leaching of heavy metals in vitrified slag rate of speed. The pH value of leaching solution are from 2 to 12, the experiment was kept at different external temperature, from 4 degree Celsius to 70 degree celsius, for 1 week to 1 month. Heavy metal leaching concentration was used to measure the chemical stability of vitrified slag. The results show that the higher specific surface area, the higher heavy metal leaching concentration, but when the specific surface area reaches a certain value, little change in leaching concentration. The impact of temperature on leaching concentration was not significant, from 4 degree Celsius to 70 degree Celsius. The leaching concentration increases with decreasing of the pH value of leaching solution when the pH value of leaching solution less than 7, and little change in concentration increases with pH value when the pH value of leaching solution more than 7. Compared with the leaching concentration after 1 month, the leaching concentration after 1 week has not changed significantly. (Author)

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

International Nuclear Information System (INIS)

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

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

Science.gov (United States)

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.

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

Science.gov (United States)

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.

Effects of freshwater leaching on potential bioavailability of heavy metals in tidal flat soils.

Science.gov (United States)

Li, Hui; Lu, Jun; Li, Qu-Sheng; He, Bao-Yan; Mei, Xiu-Qin; Yu, Dan-Ping; Xu, Zhi-Min; Guo, Shi-Hong; Chen, Hui-Jun

2016-02-01

Leaching experiments were conducted to investigate the effects of desalination levels and sediment depths on potential bioavailability of heavy metal (Cd, Cr, Cu, Fe, Mn, Ni, Pb, and Zn) in tidal flat soils. The data showed that both the desalination levels (p soil depths (p toxicity to benthic organisms than high desalination treatment. Since these reclaimed tidal flats with low desalinisation are suitable for saline water aquaculture, transforming the present land use of reclaimed tidal flats from fresh water aquaculture into saline water aquaculture may reduce health risk of heavy metals remained in sediments. These results will also contribute to our understanding of the dynamic behavior of heavy metals in the reclamation of tidal flats during leaching and the role of the ratio of SEM/AVS predictions on assessing the ecological risks of reclaimed tidal flats.

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

International Nuclear Information System (INIS)

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

Behaviour of metalloids and metals from highly polluted soil samples when mobilized by water--evaluation of static versus dynamic leaching.

Science.gov (United States)

Wennrich, Rainer; Daus, Birgit; Müller, Karsten; Stärk, Hans-Joachim; Brüggemann, Lutz; Morgenstern, Peter

2012-06-01

The mobilization behaviour of metalloids and metals when leached by water from highly polluted soil/sediment samples was studied using static and dynamic approaches employing batch methodology and rotating coiled columns (RCC), respectively. Increasing the solution-to-solid ratios during batch leaching resulted in different enhanced mobilization rates, which are element-specific and matrix-specific. When dynamic leaching is employed with continuous replacement of the eluent, a higher portion is mobilized than when using batch elution with an identical solid-to-water ratio. Using RCC the time-resolved leaching of the elements was monitored to demonstrate the leaching patterns. For the majority of elements a significant decrease could be shown in the mobilized portion of the elements with ongoing leaching process. The data were discussed targeted at solid liquid partitioning coefficients of the metal(loid)s. The capabilities in application of K(d) values was demonstrated for dynamic leaching which is relevant for environmental processes. Copyright © 2012 Elsevier Ltd. All rights reserved.

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

Science.gov (United States)

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

2016-03-01

The spent fluorescent lamps (SFLs) are being classified as a hazardous waste due to having mercury as one of its main components. Mercury is considered the second most toxic heavy metal (arsenic is the first) with harmful effects on animal nervous system as it causes different neurological disorders. In this research, the mercury from phosphor powder was leached, then bioremediated using bacterial strains isolated from Qatari environment. Leaching of mercury was carried out with nitric and hydrochloric acid solutions using two approaches: leaching at ambient conditions and microwave-assisted leaching. The results obtained from this research showed that microwave-assisted leaching method was significantly better in leaching mercury than the acid leaching where the mercury leaching efficiency reached 76.4%. For mercury bio-uptake, twenty bacterial strains (previously isolated and purified from petroleum oil contaminated soils) were sub-cultured on Luria Bertani (LB) plates with mercury chloride to check the bacterial tolerance to mercury. Seven of these twenty strains showed a degree of tolerance to mercury. The bio-uptake capacities of the promising strains were investigated using the mercury leached from the fluorescent lamps. Three of the strains (Enterobacter helveticus, Citrobacter amalonaticus, and Cronobacter muytjensii) showed bio-uptake efficiency ranged from 28.8% to 63.6%. Copyright © 2015 Elsevier Ltd. All rights reserved.

Effect of Acid Dissolution Conditions on Recovery of Valuable Metals from Used Plasma Display Panel Scrap

Directory of Open Access Journals (Sweden)

Kim Chan-Mi

2017-06-01

Full Text Available The objective of this particular study was to recover valuable metals from waste plasma display panels using high energy ball milling with subsequent acid dissolution. Dissolution of milled (PDP powder was studied in HCl, HNO3, and H2SO4 acidic solutions. The effects of dissolution acid, temperature, time, and PDP scrap powder to acid ratio on the leaching process were investigated and the most favorable conditions were found: (1 valuable metals (In, Ag, Mg were recovered from PDP powder in a mixture of concentrated hydrochloric acid (HCl:H2O = 50:50; (2 the optimal dissolution temperature and time for the valuable metals were found to be 60°C and 30 min, respectively; (3 the ideal PDP scrap powder to acid solution ratio was found to be 1:10. The proposed method was applied to the recovery of magnesium, silver, and indium with satisfactory results.

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

Energy Technology Data Exchange (ETDEWEB)

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.

Reduction of UF4 to U-metal

International Nuclear Information System (INIS)

Namkung, H.; Min, B.T.; Kim, J.S.; Whang, S.C.

1982-01-01

In the second years of study for the production of the metallic uranium with reactors which can produce 1 Kg and 4 Kg U-metal, various factors on the yield of U-metal and the leaching condition for uranium recovery with nitric acid are examined. The jolter has been used for the charging with liner (MgF 2 ) while the hand-tamping method for the filling of reaction mixtures (UF 4 -Mg) in the reactor, and their average densities are 1.23g/cc and 2.90g/cc, respectively. The various effects on the yield such as magnesium excess, furnace control temperatue, charge densities of liner and reaction mixtures, have been studied but the yields of crude metal production are in the wide range from 93 % down to about 65 %. Generally, six percent magnesium excess produced higher yields than did either 2 or 10 percent excess. The leaching condition for the uranium recovery from slag are also investigated with dilute nitric acid (3-6N) as well as higher concentrated nitric acid (9.5N) but the leaching yields are same in either solution. Uranium recovery from the slag is very effective with dilute nitric acid (3N) leaching for less than one hour at 60degC. (Author)

Solution chemistry and separation of metal ions in leached solution

International Nuclear Information System (INIS)

Shibata, J.

1991-01-01

The method to presume a dissolved state of metal ions in an aqueous solution and the technology to separate and concentrate metal ions in a leached solution are described in this paper. It is very important for the separation of metal ions to know the dissolved state of metal ions. If we know the composition of an aqueous solution and the stability constants of metal-ligand complexes, we can calculate and estimate the concentration of each species in the solution. Then, we can decide the policy to separate and concentrate metal ions. There are several methods for separation and purification; hydroxide precipitation method, sulfide precipitation method, solvent extraction method and ion exchange resin method. Solvent extraction has been used in purification processes of copper refinery, uranium refinery, platinum metal refinery and rare earth metal refinery. Fundamental process of solvent extraction, a kind of commercial extractants, a way of determining a suitable extractant and an equipment are discussed. Finally, it will be emphasized how the separation of rare earths is improved in solvent extraction. (author) 21 figs., 8 tabs., 8 refs

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

Energy Technology Data Exchange (ETDEWEB)

McDowell, Rocklan; Dutech, Guy

2014-09-01

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

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

International Nuclear Information System (INIS)

McDowell, Rocklan; Dutech, Guy

2014-01-01

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

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

DEFF Research Database (Denmark)

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...

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

International Nuclear Information System (INIS)

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)

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

International Nuclear Information System (INIS)

Khakimov, N.; Nazarov, Kh.M.; Mirsaidov, I.U.

2012-01-01

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

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

Science.gov (United States)

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.

Relation between leaching characteristics of heavy metals and physical properties of fly ashes from typical municipal solid waste incinerators.

Science.gov (United States)

Ni, Peng; Li, Hailong; Zhao, Yongchun; Zhang, Junying; Zheng, Chuguang

2017-09-01

Due to the alkalinity and high concentration of potentially hazardous heavy metals, fly ash from a municipal solid waste (MSW) incinerator is classified as hazardous waste, which should be of particular concern. Physical and chemical characterizations of the contrasted fly ashes were investigated to explore the relation between leaching characteristics of heavy metals and physical properties of fly ashes. The results showed that CaClOH, NaCl, Ca(OH) 2 , KCl and SiO 2 were primary mineral compositions in the MSWI fly ashes, and the particle size distribution of fly ash ranged between 10 μm and 300 μm. The smaller the particle size distribution of fly ash, the larger the BET-specific surface area, which was beneficial to the leaching of heavy metals. As a result of various pores, it easily accumulated heavy metals as well. The leaching tests exhibited a high leachability of heavy metals and the leaching concentration of Pb in almost all of the fly ash samples went far beyond the Standard for Pollution Control on the Landfill Site of Municipal Solid Waste. Thereupon, it is necessary to establish proper disposal systems and management strategies for environmental protection based on the characteristics of MSW incineration (MSWI) fly ash in China.

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

Directory of Open Access Journals (Sweden)

Mendes F.D.

2003-01-01

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

Molybdenum isotope fractionation during acid leaching of a granitic uranium ore

Science.gov (United States)

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

A study of marine pollution caused by the release of metals into seawater following acid spills.

Science.gov (United States)

Cabon, Jean-Yves; Giamarchi, Philippe; Le Floch, Stephane

2010-07-01

This study examined the potential metal pollution induced by the accidental spill of different acids into seawater. The acids sink to the bottom according to their densities and subsequently react with marine sediments. The acids selected for this study were acetic, hydrochloric, nitric, sulfuric, and phosphoric acids; the metallic elements selected were Cr, Cu, Fe, Mn, Pb and Zn. The sediment was collected in Brest Harbour. The percentages of metals released from this sediment in the presence of various concentrations of acids in seawater were important; concentrations of approximately 7 mg L(-1) for Mn and 60 mg L(-1) for Zn were observed under our experimental conditions. We also examined the rate of release of these metals from the sediment into the seawater in the presence of the different acids and under different experimental conditions. We found that most of the metallic elements were released from the sediments into the seawater during the first fifteen minutes of exposure. After this time, a high degree of pollution was induced if acids leached into seawater were not rapidly diluted. Copyright 2010 Elsevier Ltd. All rights reserved.

A study on the selection of indigenous leaching-bacteria for effective bioleaching

Science.gov (United States)

Oh, S. J.; Cho, K. H.; Kim, B. J.; Choi, N. C.; Park, C. Y.

2012-04-01

Bioleaching technology, which is based on the ability of microorganisms to transform solid compounds into soluble and extractable valuable elements that can be recovered, has been rapidly developed in recent decades for its advantages, which include mild reaction condition, low energy consumption, simple process, low environmental impact and being suitable for low grade mine tailings and residues. The bacteria activities (survival, adaptation of toxically environments etc.) in the bioleaching technology play a key role in the solubilization of metals. The purpose of this study was to selection of optimal leaching-bacteria through changed pH and redox potential on bio-oxidation in batch experiments for successful bioleaching technology. Twenty three indigenous bacteria used throughout this study, leaching-bacteria were obtained from various geochemical conditions; bacteria inhabitation type (acid mine drainage, mine wastes leachate and sulfur hot springs) and base-metal type (sulfur, sulfide, iron and coal). Bio-oxidation experiment result was showed that 9 cycles (1 cycle - 28days) after the leaching-bacteria were inoculated to a leaching medium, pH was observed decreasing and redox potential increased. In the bacteria inhabitation type, bio-oxidation of sulfur hot springs bacteria was greater than other types (acid mine drainage and mine wastes leachate). In addition, bio-oxidation on base-metal type was appeared sulfur was greater than other types (sulfide, iron and coal). This study informs basic knowledge when bacteria apply to eco-/economic resources utilization studies including the biomining and the recycling of mine waste system.

Decontamination method for radiation-contaminated metal waste

International Nuclear Information System (INIS)

Suwa, Takeshi; Kuribayashi, Nobuhide; Yasumune, Taketoshi.

1991-01-01

In immersing radiation-contaminated metal wastes into a sulfuric acid solution thereby peeling and removing radioactive deposition cruds and dissolving the surface of the matrix metals to eliminate radioactive contaminants, when the potential of the sulfuric acid solution is shifted to a higher direction by more than a certain level due to the increase of the amount of metal ions leached from the cruds and the matrix material, the leached metal ions are electrolytically reduced to control the potential of the sulfuric acid solution to less than a predetermined potential level. Although the dissolving rate is increased as the concentration of the sulfuric acid solution is higher, it is preferably from 0.5 to 2 mol/l, since higher concentration increases the load on the waste liquid processing. Further, the temperature for solution is set to higher than a room temperature and, preferably from 50 to 90degC. Further, the potential level of the solution, although varies somewhat depending on the concentration of the leached metal ions and the temperature, is preferably controlled to less than 0.1 to 0.2 V. This can attain high decontaminating effect in a short period of time by using a sulfuric acid solution alone. (T.M.)

EDTA-assisted phytoextraction of heavy metals by turfgrass from municipal solid waste compost using permeable barriers and associated potential leaching risk.

Science.gov (United States)

Zhao, Shulan; Lian, Fei; Duo, Lian

2011-01-01

A column experiment with horizontal permeable barriers was conducted to investigate phytoextraction of heavy metals by Lolium perenne L. from municipal solid waste compost following EDTA application, as well as to study the effects of L. perenne and permeable barriers on preventing metal from leaching. In columns with barriers, EDTA addition yielded maximum concentrations of Cu, Zn and Pb of 155, 541 and 33.5 mg kg(-1) in shoot, respectively. This led to 4.2, 2.1 and 7.4 times higher concentrations of Cu, Zn and Pb compared to treatment with no chelating agent, respectively. In treatments with 10 mmol kg(-1) EDTA, the barriers reduced leaching of Cu, Zn and Pb by approximately three times, respectively, resulting in leaching of total initial Cu, Zn and Pb by 27.3%, 25.2% and 28.8%, respectively, after four times' irrigation. These results indicate that L. perenne and permeable barriers are effective to reduce leaching of heavy metals and minimize the risk of contaminating groundwater in EDTA-enhanced phytoremediation. Thus these findings highlight that turfgrass and permeable barriers can effectively prevent metal leaching. Copyright © 2010 Elsevier Ltd. All rights reserved.

Heavy Metal Pollution Potential of Zinc Leach Residues Discarded in çinkur Plant

OpenAIRE

ALTUNDOĞAN, H. Soner; ERDEM, Mehmet; ORHAN, Ramazan

1998-01-01

In this paper, results of the study on heavy metals solubility behaviour of filter cakes from leaching of clinkerized Waelz oxide and flue dust collected during clinkerization in çinkur plant are given. The release of heavy metals into water was investigated by subjecting the cakes to solubility tests systematically. The effect of contact time, pH, liquid/solid ratio and successive extractions on the releasing of heavy metals (Cd, Pb, Mn and Zn) into water was examined and their conc...

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

Science.gov (United States)

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.

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

Energy Technology Data Exchange (ETDEWEB)

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)

Mass spectrographic analysis of selected chemical elements by microbial leaching of zircon

International Nuclear Information System (INIS)

Becker, S.; Dietze, H.J.; Bullmann, M.; Iske, U.

1986-01-01

Spark source mass spectrometry is a useful method for chemical element analysis of geological and biological samples. This sensitive technique (detection limit down to the ppb-range) is used to analyze leaching processes by means of several microorganisms. The problem of microbial leaching of chemical resistent materials was tested under laboratory conditions with regard to possible analytical and technical applications. Leaching of metals with chemolithotrophic and heterotrophic, organic acids producing microorganisms has been investigated with zircon from the Baltic Shield containing 0.7% rare earth elements and 1.67% hafnium. When zircon is leached with strains of thiobacillus ferrooxidans about 80% of the rare earth elements, Hf, Th and U can be recovered. (orig.) [de

Comparison of three-stage sequential extraction and toxicity characteristic leaching tests to evaluate metal mobility in mining wastes

International Nuclear Information System (INIS)

Margui, E.; Salvado, V.; Queralt, I.; Hidalgo, M.

2004-01-01

Abandoned mining sites contain residues from ore processing operations that are characterised by high concentrations of heavy metals. The form in which a metal exists strongly influences its mobility and, thus, the effects on the environment. Operational methods of speciation analysis, such as the use of sequential extraction procedures, are commonly applied. In this work, the modified three-stage sequential extraction procedure proposed by the BCR (now the Standards, Measurements and Testing Programme) was applied for the fractionation of Ni, Zn, Pb and Cd in mining wastes from old Pb-Zn mining areas located in the Val d'Aran (NE Spain) and Cartagena (SE Spain). Analyses of the extracts were performed by inductively coupled plasma atomic emission spectrometry and electrothermal atomic absorption spectrometry. The procedure was evaluated by using a certified reference material, BCR-701. The results of the partitioning study indicate that more easily mobilised forms (acid exchangeable) were predominant for Cd and Zn, particularly in the sample from Cartagena. In contrast, the largest amount of lead was associated with the iron and manganese oxide fractions. On the other hand, the applicability of lixiviation tests commonly used to evaluate the leaching of toxic species from landfill disposal (US-EPA Toxicity Characteristic Leaching Procedure and DIN 38414-S4) to mining wastes was also investigated and the obtained results compared with the information on metal mobility derivable from the application of the three-stage sequential extraction procedure

Selective extraction and recovery of rare earth metals from phosphor powders in waste fluorescent lamps using an ionic liquid system.

Science.gov (United States)

Yang, Fan; Kubota, Fukiko; Baba, Yuzo; Kamiya, Noriho; Goto, Masahiro

2013-06-15

The recycling of rare earth metals from phosphor powders in waste fluorescent lamps by solvent extraction using ionic liquids was studied. Acid leaching of rare earth metals from the waste phosphor powder was examined first. Yttrium (Y) and europium (Eu) dissolved readily in the acid solution; however, the leaching of other rare earth metals required substantial energy input. Ionization of target rare earth metals from the waste phosphor powders into the leach solution was critical for their successful recovery. As a high temperature was required for the complete leaching of all rare earth metals, ionic liquids, for which vapor pressure is negligible, were used as an alternative extracting phase to the conventional organic diluent. An extractant, N, N-dioctyldiglycol amic acid (DODGAA), which was recently developed, showed a high affinity for rare earth metal ions in liquid-liquid extraction although a conventional commercial phosphonic extractant did not. An effective recovery of the rare earth metals, Y, Eu, La and Ce, from the metal impurities, Fe, Al and Zn, was achieved from the acidic leach solution of phosphor powders using an ionic liquid containing DODGAA as novel extractant system. Copyright © 2013 Elsevier B.V. All rights reserved.

Alternative leaching processes for uranium ores

International Nuclear Information System (INIS)

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

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

Science.gov (United States)

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.

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

International Nuclear Information System (INIS)

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.

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

Science.gov (United States)

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.

Bacterial leaching of waste uranium materials.

Science.gov (United States)

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.

Bacterial leaching of waste uranium materials

International Nuclear Information System (INIS)

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)

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

International Nuclear Information System (INIS)

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

A New Generation of Leaching Tests – The Leaching Environmental Assessment Framework

Science.gov (United States)

Provides an overview of newly released leaching tests that provide a more accurate source term when estimating environmental release of metals and other constituents of potential concern (COPCs). The Leaching Environmental Assessment Framework (LEAF) methods have been (1) develo...

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

Science.gov (United States)

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.

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

Science.gov (United States)

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

2017-02-01

The leaching behaviors of primary copper (Cu) slags originating from Ausmelt, reverbatory, and converter furnaces operating under a single technological process were compared to a residual slag tailing obtained by slag re-processing via flotation and metal recovery. The EN 12457-2 leaching test, used for assessment of the hazardous properties, was followed by the CEN/TS 14997 pH-static leaching test (pH range 3-12). Both leaching experiments were coupled with a mineralogical investigation of the primary and secondary phases as well as geochemical modeling. Metals (Cd, Cu, Pb, Zn) exhibit the highest leaching at low pH. Under acidic conditions (pH 3-6), Ausmelt slag and slag tailing exhibited higher metal leaching compared to other slag types. Very low leaching of metals (far below EU limits for non-hazardous waste) was observed at natural pH (7.9-9.0) for all the studied slag samples. In contrast, relatively high leaching of As was observed over the entire pH range, especially for Ausmelt slag (exceeding the EU limit for hazardous waste by 1.7×). However, geochemical modeling and scanning electron microscopy indicated that formation of stable Ca-Cu-Pb arsenates and the binding of As to newly formed Fe (oxyhydr)oxides play an important role in efficient As immobilization at the slag-water interface. In contrast, no controls were predicted for Sb, whose leaching was almost pH-independent. Nevertheless Sb leached concentrations at natural pH were below EU limit for hazardous waste. Re-processing of primary Cu slags for metal recovery, and subsequent co-disposal of the resulting slag tailing with dolomite-rich mine tailing and local laterite is suitable for stabilizing the remaining contaminants (except Sb) and limiting their leaching into the environment. Copyright © 2016 Elsevier Ltd. All rights reserved.

Selective leaching process for the recovery of copper and zinc oxide from copper-containing dust.

Science.gov (United States)

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.

Investigations on microbial leaching of zircon by means of spark source mass spectrometry

International Nuclear Information System (INIS)

Becker, S.; Dietze, H.J.; Bullmann, M.; Iske, U.

1985-01-01

Spark source mass spectrometry is a useful method for chemical element analysis of geological and biological samples. This sensitive technique (detection limit down to the ppb-range) is used to analyze leaching processes by means of several microorganisms. The problem of microbial leaching of chemical resistent materials was tested under laboratory condition with regard to possible analytical and technical applications. Leaching of metalls with chemolithotrophic and heterotrophic, organic acids producing microorganisms has been investigated with zircon from Baltic Shield containing 0.7% rare earth elements and 1.67% hafnium. When zircon is leached with strains of Thiobacillus ferroxidans the rare earth elements, Hf, Th, and U mostly (about 80%) can be recovered. (author)

Development of an accelerated leaching method for incineration bottom ash correlated to toxicity characteristic leaching protocol.

Science.gov (United States)

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.

Effect of accelerated carbonation and zero valent iron on metal leaching from bottom ash.

Science.gov (United States)

Nilsson, M; Andreas, L; Lagerkvist, A

2016-05-01

About 85% of the ashes produced in Sweden originated from the incineration of municipal solid waste and biofuel. The rest comes from the thermal treatment of recycled wood, peat, charcoal and others. About 68% of all ashes annually produced in Sweden are used for constructions on landfills, mainly slopes, roads and embankments, and only 3% for construction of roads and working surfaces outside the landfills (SCB, 2013). Since waste bottom ash (BA) often has similar properties to crushed bedrock or gravel, it could be used for road constructions to a larger extent. However, the leaching of e.g. Cr, Cu, Mo, Pb and Zn can cause a threat to the surrounding environment if the material is used as it is. Carbonation is a commonly used pre-treatment method, yet it is not always sufficient. As leaching from aged ash is often controlled by adsorption to iron oxides, increasing the number of Fe oxide sorption sites can be a way to control the leaching of several critical elements. The importance of iron oxides as sorption sites for metals is known from both mineralogical studies of bottom ash and from the remediation of contaminated soil, where iron is used as an amendment. In this study, zero valent iron (Fe(0)) was added prior to accelerated carbonation in order to increase the number of adsorption sites for metals and thereby reduce leaching. Batch, column and pHstat leaching tests were performed and the leaching behaviour was evaluated with multivariate data analysis. It showed that leaching changed distinctly after the tested treatments, in particular after the combined treatment. Especially, the leaching of Cr and Cu clearly decreased as a result of accelerated carbonation. The combination of accelerated carbonation with Fe(0) addition reduced the leaching of Cr and Cu even further and reduced also the leaching of Mo, Zn, Pb and Cd compared to untreated BA. Compared with only accelerated carbonation, the Fe(0) addition significantly reduced the leaching of Cr, Cu and Mo

Recovery and Separation of Valuable Metals from Spent Nickel-Metal Hydride Batteries using some Organophosphorus Extractants

International Nuclear Information System (INIS)

Aly, M.I.; Daoud, J.A.; ALy, H.F.

2012-01-01

The separation of cobalt, nickel, and rare earth elements from NiMH battery residues is evaluated in this paper. A hydrometallurgical process is developed for the recovery of metals from spent batteries and a selective separation of RE by precipitation of sodium RE double sulfate is performed. The methodology used benefits the solubility of the battery electrode materials in sulfuric or hydrochloric acids. The results obtained show that sulfuric acid is slightly less powerful in leaching (NiMH) compared to HCl acid. However, sulfuric acid was used on economic basis. Leaching solution was obtained by using 3 M H 2 SO 4 at 70 +1 degree C + 3% wt. H 2 O 2 for 5 hours. It has been shown that it is possible to recover about 98 % of the RE contained in spent NiMH batteries. The maximum recovery of nickel and cobalt metals was 99.9% and 99.4%, respectively. The effects of the main operating variables of both leaching and solvent extraction steps of nickel (II) and cobalt (II) from the leach solution using HDEHP (di-2-ethylhexyl phosphoric acid) and CYANEX 272 (di-(2,4,4 trimethyl pentyl) phosphinic acid) in kerosene were investigated aiming to maximize metal separation for recycling purposes. The developed process for the recovery and separation of nickel (II) , cobalt (II), and rare earth from spent NiMH batteries is tested and the obtained sulfate salts CoSO 4 and NiSO 4 have a high purity, suggesting that these recovered products could be used as chemical materials without further purification

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

Directory of Open Access Journals (Sweden)

Aichun Zhao

2016-01-01

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

Leaching Process of Rare Earth Elements, Gallium and Niobium in a Coal-Bearing Strata-Hosted Rare Metal Deposit—A Case Study from the Late Permian Tuff in the Zhongliangshan Mine, Chongqing

Directory of Open Access Journals (Sweden)

Jianhua Zou

2017-05-01

Full Text Available The tuff, a part of coal-bearing strata, in the Zhongliangshan coal mine, Chongqing, southwestern China, hosts a rare metal deposit enriched in rare earth elements (REE, Ga and Nb. However, the extraction techniques directly related to the recovery of rare metals in coal-bearing strata have been little-studied in the literature. The purpose of this paper is to investigate the extractability of REE, Ga and Nb in the tuff in the Zhongliangshan mine using the alkaline sintering-water immersion-acid leaching (ASWIAL method. The results show that ASWIAL can separate and extract REE, Ga and Nb effectively under the optimized conditions of calcining at 860 °C for 0.5 h with a sample to sintering agent ratio of 1:1.5, immersing at 90 °C for 2 h with 150 mL hot water dosage, and leaching using 4 mol/L HCl at 40 °C for 2 h with a liquid-solid ratio of 20:1 (mL:g. The final leaching efficiencies of REE and Ga are up to 85.81% and 93.37%, respectively, whereas the leaching efficiency of Nb is less than 1%, suggesting the high concentration of Nb in the leaching residue, which needs further extraction.

Statistical comparison of leaching behavior of incineration bottom ash using seawater and deionized water: Significant findings based on several leaching methods.

Science.gov (United States)

Yin, Ke; Dou, Xiaomin; Ren, Fei; Chan, Wei-Ping; Chang, Victor Wei-Chung

2018-02-15

Bottom ashes generated from municipal solid waste incineration have gained increasing popularity as alternative construction materials, however, they contains elevated heavy metals posing a challenge for its free usage. Different leaching methods are developed to quantify leaching potential of incineration bottom ashes meanwhile guide its environmentally friendly application. Yet, there are diverse IBA applications while the in situ environment is always complicated, challenging its legislation. In this study, leaching tests were conveyed using batch and column leaching methods with seawater as opposed to deionized water, to unveil the metal leaching potential of IBA subjected to salty environment, which is commonly encountered when using IBA in land reclamation yet not well understood. Statistical analysis for different leaching methods suggested disparate performance between seawater and deionized water primarily ascribed to ionic strength. Impacts of leachant are metal-specific dependent on leaching methods and have a function of intrinsic characteristics of incineration bottom ashes. Leaching performances were further compared on additional perspectives, e.g. leaching approach and liquid to solid ratio, indicating sophisticated leaching potentials dominated by combined geochemistry. It is necessary to develop application-oriented leaching methods with corresponding leaching criteria to preclude discriminations between different applications, e.g., terrestrial applications vs. land reclamation. Copyright © 2017 Elsevier B.V. All rights reserved.

Metal mobilization from metallurgical wastes by soil organic acids.

Science.gov (United States)

Potysz, Anna; Grybos, Malgorzata; Kierczak, Jakub; Guibaud, Gilles; Fondaneche, Patrice; Lens, Piet N L; van Hullebusch, Eric D

2017-07-01

Three types of Cu-slags differing in chemical and mineralogical composition (historical, shaft furnace, and granulated slags) and a matte from a lead recovery process were studied with respect to their susceptibility to release Cu, Zn and Pb upon exposure to organic acids commonly encountered in soil environments. Leaching experiments (24-960 h) were conducted with: i) humic acid (20 mg/L) at pH t 0  = 4.4, ii) fulvic acid (20 mg/L) at pH t 0  = 4.4, iii) an artificial root exudates (ARE) (17.4 g/L) solution at pH t 0  = 4.4, iv) ARE solution at pH t 0  = 2.9 and v) ultrapure water (pH t 0  = 5.6). The results demonstrated that the ARE contribute the most to the mobilization of metals from all the wastes analyzed, regardless of the initial pH of the solution. For example, up to 14%, 30%, 24% and 5% of Cu is released within 960 h from historical, shaft furnace, granulated slags and lead matte, respectively, when exposed to the artificial root exudates solution (pH 2.9). Humic and fulvic acids were found to have a higher impact on granulated and shaft furnace slags as compared to the ultrapure water control and increased the release of metals by a factor up to 37.5 (Pb) and 20.5 (Cu) for granulated and shaft furnace slags, respectively. Humic and fulvic acids amplified the mobilization of metals by a maximal factor of 13.6 (Pb) and 12.1 (Pb) for historical slag and lead matte, respectively. The studied organic compounds contributed to different release rates of metallic contaminants from individual metallurgical wastes under the conditions tested. Copyright © 2017 Elsevier Ltd. All rights reserved.

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

NARCIS (Netherlands)

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

2001-01-01

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

Leaching of Heavy Metals Using SPLP Method from Fired Clay Brick Incorporating with Sewage Sludge

Science.gov (United States)

Kadir, Aeslina Abdul; Salim, Nurul Salhana Abdul; Amira Sarani, Noor; Aqma Izurin Rahmat, Nur

2017-05-01

Sewage sludge is a by-product generate from wastewater treatment process. The sewage sludge contains significant trace metal such as Cr, Mn, Ni, Cu, Zn, As, Cd and Pb which are toxic to the environment. Sewage sludge is disposed of by landfilling method. However, this option not suitable because of land restriction and environmental control regulations imposed. Therefore, sewage sludge from wastewater treatment plant was incorporated into fired clay brick to produce good quality of brick as well as reducing heavy metals from sludge itself. Sewage sludge with 0%, 1%, 5%, 10% and 20% of were incorporated into fired clay bricks and fired at 1050°C temperature with heating rates of 1°C/min. The brick sample then crushed and sieved through 9.5 mm sieve for Synthetic Precipitation Leaching Procedure (SPLP). From the results, incorporation up to 20% of sewage sludge has leached less heavy metals and compliance with USEPA standard.

Coal fly ash-slag-based geopolymers: microstructure and metal leaching.

Science.gov (United States)

Izquierdo, Maria; Querol, Xavier; Davidovits, Joseph; Antenucci, Diano; Nugteren, Henk; Fernández-Pereira, Constantino

2009-07-15

This study deals with the use of fly ash as a starting material for geopolymeric matrices. The leachable concentrations of geopolymers were compared with those of the starting fly ash to evaluate the retention of potentially harmful elements within the geopolymer matrix. Geopolymer matrices give rise to a leaching scenario characterised by a highly alkaline environment, which inhibits the leaching of heavy metals but may enhance the mobilization of certain oxyanionic species. Thus, fly ash-based geopolymers were found to immobilize a number of trace pollutants such as Be, Bi, Cd, Co, Cr, Cu, Nb, Ni, Pb, Sn, Th, U, Y, Zr and rare earth elements. However, the leachable levels of elements occurring in their oxyanionic form such as As, B, Mo, Se, V and W were increased after geopolymerization. This suggests that an optimal dosage, synthesis and curing conditions are essential in order to obtain a long-term stable final product that ensures an efficient physical encapsulation.

Coal fly ash-slag-based geopolymers: Microstructure and metal leaching

Energy Technology Data Exchange (ETDEWEB)

Izquierdo, Maria, E-mail: mariaizq@ija.csic.es [Institute of Earth Sciences ' Jaume Almera' -CSIC, Lluis Sole Sabaris s/n 08028 Barcelona (Spain); Querol, Xavier [Institute of Earth Sciences ' Jaume Almera' -CSIC, Lluis Sole Sabaris s/n 08028 Barcelona (Spain); Davidovits, Joseph [Cordi-Geopolymere, Espace Creatis, Z.A. Bois de la Chocque 02100 Saint-Quentin (France); Antenucci, Diano [Institut Scientifique de Service Public (ISSeP) 200, rue du Chera, B-4000 Liege (Belgium); Nugteren, Henk [Delft University of Technology, Faculty of Applied Sciences, DelftChemTech, Particle Technology Group, Julianalaan 136, 2628 BL Delft (Netherlands); Fernandez-Pereira, Constantino [University of Seville, School of Industrial Engineering, Department of Chemical and Environmental Engineering, Camino de los Descubrimientos s/n, 41092 Seville (Spain)

2009-07-15

This study deals with the use of fly ash as a starting material for geopolymeric matrices. The leachable concentrations of geopolymers were compared with those of the starting fly ash to evaluate the retention of potentially harmful elements within the geopolymer matrix. Geopolymer matrices give rise to a leaching scenario characterised by a highly alkaline environment, which inhibits the leaching of heavy metals but may enhance the mobilization of certain oxyanionic species. Thus, fly ash-based geopolymers were found to immobilise a number of trace pollutants such as Be, Bi, Cd, Co, Cr, Cu, Nb, Ni, Pb, Sn, Th, U, Y, Zr and rare earth elements. However, the leachable levels of elements occurring in their oxyanionic form such as As, B, Mo, Se, V and W were increased after geopolymerization. This suggests that an optimal dosage, synthesis and curing conditions are essential in order to obtain a long-term stable final product that ensures an efficient physical encapsulation.

Coal fly ash-slag-based geopolymers: Microstructure and metal leaching

International Nuclear Information System (INIS)

Izquierdo, Maria; Querol, Xavier; Davidovits, Joseph; Antenucci, Diano; Nugteren, Henk; Fernandez-Pereira, Constantino

2009-01-01

This study deals with the use of fly ash as a starting material for geopolymeric matrices. The leachable concentrations of geopolymers were compared with those of the starting fly ash to evaluate the retention of potentially harmful elements within the geopolymer matrix. Geopolymer matrices give rise to a leaching scenario characterised by a highly alkaline environment, which inhibits the leaching of heavy metals but may enhance the mobilization of certain oxyanionic species. Thus, fly ash-based geopolymers were found to immobilise a number of trace pollutants such as Be, Bi, Cd, Co, Cr, Cu, Nb, Ni, Pb, Sn, Th, U, Y, Zr and rare earth elements. However, the leachable levels of elements occurring in their oxyanionic form such as As, B, Mo, Se, V and W were increased after geopolymerization. This suggests that an optimal dosage, synthesis and curing conditions are essential in order to obtain a long-term stable final product that ensures an efficient physical encapsulation.

Solidification/stabilization of ASR fly ash using Thiomer material: Optimization of compressive strength and heavy metals leaching.

Science.gov (United States)

Baek, Jin Woong; Choi, Angelo Earvin Sy; Park, Hung Suck

2017-12-01

Optimization studies of a novel and eco-friendly construction material, Thiomer, was investigated in the solidification/stabilization of automobile shredded residue (ASR) fly ash. A D-optimal mixture design was used to evaluate and optimize maximum compressive strength and heavy metals leaching by varying Thiomer (20-40wt%), ASR fly ash (30-50wt%) and sand (20-40wt%). The analysis of variance was utilized to determine the level of significance of each process parameters and interactions. The microstructure of the solidified materials was taken from a field emission-scanning electron microscopy and energy dispersive X-ray spectroscopy that confirmed successful Thiomer solidified ASR fly ash due to reduced pores and gaps in comparison with an untreated ASR fly ash. The X-ray diffraction detected the enclosed materials on the ASR fly ash primarily contained sulfur associated crystalline complexes. Results indicated the optimal conditions of 30wt% Thiomer, 30wt% ASR fly ash and 40wt% sand reached a compressive strength of 54.9MPa. For the optimum results in heavy metals leaching, 0.0078mg/LPb, 0.0260mg/L Cr, 0.0007mg/LCd, 0.0020mg/L Cu, 0.1027mg/L Fe, 0.0046mg/L Ni and 0.0920mg/L Zn were leached out, being environmentally safe due to being substantially lower than the Korean standard leaching requirements. The results also showed that Thiomer has superiority over the commonly used Portland cement asa binding material which confirmed its potential usage as an innovative approach to simultaneously synthesize durable concrete and satisfactorily pass strict environmental regulations by heavy metals leaching. Copyright © 2017 Elsevier Ltd. All rights reserved.

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

Science.gov (United States)

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.

Heap leaching procedure for the Uranium extraction

International Nuclear Information System (INIS)

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

Selective extraction of metals from products of mine acidic water treatment

International Nuclear Information System (INIS)

Andreeva, N.N.; Romanchuk, S.A.; Voronin, N.N.; Demidov, V.D.; Pasynkova, T.A.; Manuilova, O.A.; Ivanova, N.V.

1989-01-01

A study was made on possibility of processing of foam products prepared during flotation purification of mine acidic waters for the purpose of selective extraction of non-ferrous (Co, Ni) and rare earth elements (REE) and their separation from the basic macrocomponent of waters-iron. Optimal conditions of selective metal extraction from foam flotation products are the following: T=333 K, pH=3.0-3.5, ratio of solid and liquid phase - 1:4-1:7, duration of sulfuric acid leaching - 30 min. Rare earth extraction under such conditions equals 87.6-93.0%. The degree of valuable component concentration equals ∼ 10. Rare earths are separated from iron by extraction methods

Trace metal mobilization from oil sands froth treatment thickened tailings exhibiting acid rock drainage.

Science.gov (United States)

Kuznetsova, Alsu; Kuznetsov, Petr; Foght, Julia M; Siddique, Tariq

2016-11-15

Froth treatment thickened tailings (TT) are a waste product of bitumen extraction from surface-mined oil sands ores. When incubated in a laboratory under simulated moist oxic environmental conditions for ~450d, two different types of TT (TT1 and TT2) exhibited the potential to generate acid rock drainage (ARD) by producing acid leachate after 250 and 50d, respectively. We report here the release of toxic metals from TT via ARD, which could pose an environmental threat if oil sands TT deposits are not properly managed. Trace metal concentrations in leachate samples collected periodically revealed that Mn and Sr were released immediately even before the onset of ARD. Spikes in Co and Ni concentrations were observed both pre-ARD and during active ARD, particularly in TT1. For most elements measured (Fe, Cr, V, As, Cu, Pb, Zn, Cd, and Se), leaching was associated with ARD production. Though equivalent acidification (pH2) was achieved in leachate from both TT types, greater metal release was observed from TT2 where concentrations reached 10,000ppb for Ni, 5000ppb for Co, 3000ppb for As, 2000ppb for V, and 1000ppb for Cr. Generally, metal concentrations decreased in leachate with time during ARD and became negligible by the end of incubation (~450d) despite appreciable metals remaining in the leached TT. These results suggest that using TT for land reclamation purposes or surface deposition for volume reduction may unfavorably impact the environment, and warrants application of appropriate strategies for management of pyrite-enriched oil sands tailings streams. Copyright © 2016 Elsevier B.V. All rights reserved.

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

Science.gov (United States)

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.

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

Science.gov (United States)

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.

Bacteria heap leaching test of a uranium ore

International Nuclear Information System (INIS)

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)

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

Energy Technology Data Exchange (ETDEWEB)

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

2014-08-15

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

Uranium leaching using mixed organic acids produced by Aspergillus niger

International Nuclear Information System (INIS)

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)

Recovery of gold from hydrometallurgical leaching solution of electronic waste via spontaneous reduction by polyaniline

Directory of Open Access Journals (Sweden)

Yuanzhao Wu

2017-08-01

Full Text Available The present study is primarily designed to develop an environmentally-benign approach for the recovery of precious metals, especially gold, from the ever increasingly-discarded electronic wastes (e-waste. By coupling the metal reduction process with an increase in the intrinsic oxidation state of the aniline polymers, and the subsequent re-protonation and reduction of the intrinsically oxidized polymer to the protonated emeraldine (EM salt, polyaniline (PANi films and polyaniline coated cotton fibers are able to recover metallic gold from acid/halide leaching solutions of electronic wastes spontaneously and sustainably. The current technique, which does not require the use of extensive extracting reagents or external energy input, can recover as much as 90% of gold from the leaching acidic solutions. The regeneration of polyaniline after gold recovery, as confirmed by the X-ray photoelectron spectroscopy measurements, promises the continuous operation using the current approach. The as-recovered elemental gold can be further concentrated and purified by incineration in air.

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

Energy Technology Data Exchange (ETDEWEB)

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.

Study of the leaching of heavy metals from waste water sludge and incinerator's ash, using coupled thermostated columns and DTPA as complex agent; Estudio de la extraccion de metales pesados de lodos y cenizas de aguas residuales usando columnas termostatizadas acopladas y DTPA como agente complejante

Energy Technology Data Exchange (ETDEWEB)

Vite T, J.; Vite T, M.; Guerrero D, J.; Carreno de Leon, M.C. [Departamento de Estudios del Ambiente, Instituto Nacional de Investigaciones Nucleares, A.P. 18-1027, 11801 Mexico D.F. (Mexico)

2000-07-01

We studied the metallic composition from waste water sludge and incinerators ashes of an incinerator located in Toluca, Mexico, the qualitative studies were made using the Activation Analysis technique, and fluorescence X-ray techniques. The quantitative analysis of heavy metals in the wastes were made using Inductively coupled plasma atomic emission spectrometry (Icp-Aes). For leaching the samples, we used four coupled thermostated columns, each one had a p H of 2,5, 7 and 10. The flux of the air was of 1600 cc/min. The temperature was maintain constant in 60 Centigrade using a thermostated system. For this study we used 100 g of wastes mixed with mineral acid or sodium hydroxide to reach p H 2,5,7 and 10. We added a reducing and tensoactive agents and finally DTPA as complex agent. With this method, we obtain a better leaching efficiency using a complex agent. However the high DTPA cost, make this process expansive that is why we recommend to work with another classes of complex agents, that be cheaper to leach metals of different chemistry matrix. (Author)

The importance of pre-treatment of spent hydrotreating catalysts on metals recovery

Directory of Open Access Journals (Sweden)

Alexandre Luiz de Souza Pereira

2011-01-01

Full Text Available This work describes a three-step pre-treatment route for processing spent commercial NiMo/Al2O3 catalysts. Extraction of soluble coke with n-hexane and/or leaching of foulant elements with oxalic acid were performed before burning insoluble coke under air. Oxidized catalysts were leached with 9 mol L-1 sulfuric acid. Iron was the only foulant element partially leached by oxalic acid. The amount of insoluble matter in sulfuric acid was drastically reduced when iron and/or soluble coke were previously removed. Losses of active phase metals (Ni, Mo during leaching with oxalic acid were compensated by the increase of their recovery in the sulfuric acid leachate.

The importance of pre-treatment of spent hydrotreating catalysts on metals recovery

Energy Technology Data Exchange (ETDEWEB)

Pereira, Alexandre Luiz de Souza; Silva, Cristiano Nunes da; Afonso, Julio Carlos, E-mail: julio@iq.ufrj.b [Universidade Federal do Rio de Janeiro (IQ/UFRJ), RJ (Brazil). Inst. de Quimica. Dept. de Quimica Analitica; Mantovano, Jose Luiz [Instituto de Engenharia Nuclear (CNEN/IEN-RJ), Rio de Janeiro, RJ (Brazil). Dept. de Quimica e Materiais Nucleares

2011-07-01

This work describes a three-step pre-treatment route for processing spent commercial Ni Mo/Al{sub 2}O{sub 3} catalysts. Extraction of soluble coke with n-hexane and/or leaching of foulant elements with oxalic acid were performed before burning insoluble coke under air. Oxidized catalysts were leached with 9 mol L{sup -1} sulfuric acid. Iron was the only foulant element partially leached by oxalic acid. The amount of insoluble matter in sulfuric acid was drastically reduced when iron and/or soluble coke were previously removed. Losses of active phase metals (Ni, Mo) during leaching with oxalic acid were compensated by the increase of their recovery in the sulfuric acid leachate. (author)

Estimation of environmental mobility of heavy metals using a sequential leaching of particulate material emitted from an opencast chrome mine complex

Energy Technology Data Exchange (ETDEWEB)

Poeykioe, R. [Meri-Lappi Institute, Centre for Environmental Technology, University of Oulu, Kemi (Finland); Peraemaeki, P.; Kuokkanen, T. [University of Oulu, Department of Chemistry, Oulu (Finland); Vaelimaeki, I. [Suomen Ympaeristoepalvelu Oy, Oulu (Finland)

2002-06-01

A four-stage sequential leaching procedure was applied to assess the bioavailability and environmental mobility of heavy metals (Cr, Fe, Cu, Ni and Cd) in total suspended particulate (TSP) material emitted from an opencast chrome mine complex (Kemi, Northern Finland). TSP material was collected on glass fibre filters by a high-volume sampler, and a sequential leaching procedure was used to determine the distribution of heavy metals between the water-soluble fraction (H{sub 2}O), environmentally mobile fraction (CH{sub 3}COONH{sub 4}), the fraction bound to carbonate and oxides (HONH{sub 3}Cl + CH{sub 3}COOH), and the fraction bound to silicates and organic matter, that is the environmentally immobile fraction (HNO{sub 3} + HF + HCl). The sequential leaching procedure was also applied to the certified reference materials VKI (QC Loam Soil A) and PACS-2 (Marine Sediment) to evaluate the accuracy and reproducibility of the leaching procedure. The heavy metals were determined by graphite furnace atomic absorption spectrometry (GFAAS) and flame atomic absorption spectrometry (FAAS). The concentrations of metals in the water-soluble fraction (H{sub 2}O) decreased in the order Fe >Cu >Cr >Ni >Cd, and in the environmentally mobile fraction (CH{sub 3}COONH{sub 4}) in the order Cu >Fe >Ni >Cr >Cd. (orig.)

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

International Nuclear Information System (INIS)

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.

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

Energy Technology Data Exchange (ETDEWEB)

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.

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

Science.gov (United States)

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.

A novel bioreactor system for simultaneous mutli-metal leaching from industrial pyrite ash: Effect of agitation and sulphur dosage.

Science.gov (United States)

Panda, Sandeep; Akcil, Ata; Mishra, Srabani; Erust, Ceren

2018-01-15

Simultaneous multi-metal leaching from industrial pyrite ash is reported for the first time using a novel bioreactor system that allows natural diffusion of atmospheric O 2 and CO 2 along with the required temperature maintenance. The waste containing economically important metals (Cu, Co, Zn & As) was leached using an adapted consortium of meso-acidophilic Fe 2+ and S oxidising bacteria. The unique property of the sample supported adequate growth and activity of the acidophiles, thereby, driving the (bio) chemical reactions. Oxido-reductive potentials were seen to improve with time and the system's pH lowered as a result of active S oxidation. Increase in sulphur dosage (>1g/L) and agitation speed (>150rpm) did not bear any significant effect on metal dissolution. The consortium was able to leach 94.01% Cu (11.75% dissolution/d), 98.54% Co (12.3% dissolution/d), 75.95% Zn (9.49% dissolution/d) and 60.80% As (7.6% dissolution/d) at 150rpm, 1g/L sulphur, 30°C in 8days. Copyright © 2017 Elsevier B.V. All rights reserved.

Recovery of metal values and hydrofluoric acid from tantalum and columbium waste sludge

International Nuclear Information System (INIS)

Bielecki, E.; Romberger, K.; Bakke, B.; Hobin, M.A.; Clark, C.

1992-01-01

A metallurgical processing system for economically recovering metal values, such as columbium, tantalum, thorium, and uranium from dilute source solids, such as digestion sludges, by a series of steps including: (1) slurrying the source solids with dilute hydrofluoric acid to produce a solid phase and a liquid phase containing dissolved tantalum and columbium, then extracting tantalum and/or columbium from the liquid phase by means of a liquid ion-exchange process and then, additionally; (2) roasting the solid phase with sulfuric acid to recover and recycle hydrofluoric acid, leaching the roasted solids with dilute sulfuric acid to produce a disposable solid phase and a liquid phase containing thorium and uranium, and extracting thorium and uranium from the liquid phase by means of a liquid-liquid amine extraction process

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

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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.

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

Energy Technology Data Exchange (ETDEWEB)

Saarinen, T.

2013-06-01

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

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

Science.gov (United States)

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

2014-08-15

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

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

International Nuclear Information System (INIS)

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)

Uranium recovery from acid leach liquors: Ix or Sx?

International Nuclear Information System (INIS)

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

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

International Nuclear Information System (INIS)

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)

Comparison of the extraction efficiencies of different leaching agents for reliable assessment of bio-accessible trace metal fractions in airborne particulate matter

Directory of Open Access Journals (Sweden)

Mukhtar A.

2013-04-01

Full Text Available In present study, an in-vitro physiologically based extraction test has been applied for extraction of bio-accessible trace metal fractions in airborne particulate matter (APM samples collected from different urban sites in Austria and Pakistan using the leaching agents H2O, sodium chloride, ammonium acetate, ammonium citrate, synthetic gastric juice and artificial lung fluids. Obtained extracts were then measured using an ETV-ICP-OES procedure which allowed highly sensitive measurement of dissolved analytes even in the presence of leaching agents. Derived results indicated that the investigated leaching agents extract different amounts of trace metals. In general, leaching agents with organic nature yielded comparatively greater extractable and thus bio-accessible trace metal fractions to that of simple solvents like H2O or aqueous NaCl solution. With water, only 26.3±4.0% of Cd was found to be bio-accessible whereas 88.4±24.8 of Cd was obtained as bio-accessible fraction with the use of synthetic gastric juice. The concentrations of bio-accessible metal fractions varied from 0.4 ng m−3 (Cd to 714 ng m−3 (Zn and 0.3 ng m−3 (Cd to 190 ng m−3 (Zn for PM10 samples collected from Karachi (Pakistan and Graz (Austria respectively.

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

Science.gov (United States)

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

2016-05-01

The spent Zn-C cell powder, containing ZnMn2O4, ZnO, MnO(OH) and possibly Mn2O3 and Mn3O4, can be leached by a sulfuric acid solution mixed with some glucose. The leaching is found to be dependent on solid to liquid (S/L) ratio, amount of glucose, concentration of sulfuric acid solution, time and pulp agitation speed. For 5g powder (S), 1h leaching time and 300rpm pulp agitation speed, two-level four-factor (2(4)) experimental designs have been carried out to derive models for extraction of both Mn(II) and Zn(II). Amount of glucose (G, g), concentration of H2SO4 solution (C, mol/L), volume of H2SO4 solution as leachant (L, mL) and leaching temperature (T, °C) are considered as factors (variables). The model in both cases consists of mean, factor effects and interaction effects. The four-factor interaction effect is observed in neither of the cases. Some two-factor and three-factor effects are found to have produced positive or negative contributions to dissolution percentage in both cases. The models are examined for comparison with experimental results with good fits and also used for optimization of factors. At optimized condition (G=0.50g, C=2mol/L, L=250mL and T=100°C), an aliquot of 5g powder in 1h and at 300rpm produces a solution containing (7.08±0.10)g/L Mn(II) and (2.20±0.06)g/L Zn(II) corresponding to almost 100% extraction of both metal ions. Copyright © 2015 Elsevier Ltd. All rights reserved.

The Study and Application of Hydrometallurgical Gold Leaching in the Analysis of Refractory Precious Metals

Science.gov (United States)

Yang, M.; Geng, X.; Wang, Y. L.; Li, D. X.

2017-05-01

Three orthogonal tests are separately designed for each hydrometallurgical gold leaching process to finding the optimum reaction conditions of melting gold and palladium in each process. Under the optimum condition, the determination amount of gold and palladium in aqua regia—hydrofluoric acid, Sodium thiosulfate, and potassium iodide reaches 2.87g/kg and 8.34 g/kg, 2.39g/kg and 8.12 g/kg, 2.51g/kg and 7.84g/kg. From the result, the content of gold and palladium using the leaching process of combining Aqua regia, hydrofluoric acid and hydrogen peroxide is relatively higher than the other processes. In addition, the experiment procedure of aqua regia digestion operates easily, using less equipment, and its period is short.

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

Science.gov (United States)

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.

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

International Nuclear Information System (INIS)

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

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

International Nuclear Information System (INIS)

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

1998-02-01

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

Recovery of metals from a mixture of various spent batteries by a hydrometallurgical process.

Science.gov (United States)

Tanong, Kulchaya; Coudert, Lucie; Mercier, Guy; Blais, Jean-Francois

2016-10-01

Spent batteries contain hazardous materials, including numerous metals (cadmium, lead, nickel, zinc, etc.) that are present at high concentrations. Therefore, proper treatment of these wastes is necessary to prevent their harmful effects on human health and the environment. Current recycling processes are mainly applied to treat each type of spent battery separately. In this laboratory study, a hydrometallurgical process has been developed to simultaneously and efficiently solubilize metals from spent batteries. Among the various chemical leaching agents tested, sulfuric acid was found to be the most efficient and cheapest reagent. A Box-Behnken design was used to identify the influence of several parameters (acid concentration, solid/liquid ratio, retention time and number of leaching steps) on the removal of metals from spent batteries. According to the results, the solid/liquid ratio and acid concentration seemed to be the main parameters influencing the solubilization of zinc, manganese, nickel, cadmium and cobalt from spent batteries. According to the results, the highest metal leaching removals were obtained under the optimal leaching conditions (pulp density = 180 g/L (w/v), [H2SO4] = 1 M, number of leaching step = 3 and leaching time = 30 min). Under such optimum conditions, the removal yields obtained were estimated to be 65% for Mn, 99.9% for Cd, 100% for Zn, 74% for Co and 68% for Ni. Further studies will be performed to improve the solubilization of Mn and to selectively recover the metals. Copyright © 2016 Elsevier Ltd. All rights reserved.

Spatial distribution of heavy metal contamination in soils near a primitive e-waste recycling site.

Science.gov (United States)

Quan, Sheng-Xiang; Yan, Bo; Yang, Fan; Li, Ning; Xiao, Xian-Ming; Fu, Jia-Mo

2015-01-01

The total concentrations of 12 heavy metals in surface soils (SS, 0-20 cm), middle soils (MS, 30-50 cm) and deep soils (DS, 60-80 cm) from an acid-leaching area, a deserted paddy field and a deserted area of Guiyu were measured. The results showed that the acid-leaching area was heavily contaminated with heavy metals, especially in SS. The mean concentrations of Ni, Cu, Zn, Cd, Sn, Sb and Pb in SS from the acid-leaching area were 278.4, 684.1, 572.8, 1.36, 3,472, 1,706 and 222.8 mg/kg, respectively. Heavy metal pollution in the deserted paddy field was mainly concentrated in SS and MS. The average values of Sb in SS and MS from the deserted paddy field were 16.3 and 20.2 mg/kg, respectively. However, heavy metal contamination of the deserted area was principally found in the DS. Extremely high concentrations of heavy metals were also observed at some special research sites, further confirming that the level of heavy metal pollution was very serious. The geoaccumulation index (Igeo) values revealed that the acid-leaching area was severely polluted with heavy metals in the order of Sb > Sn > Cu > Cd > Ni > Zn > Pb, while deserted paddy field was contaminated predominately by metals in the order of Sb > Sn > Cu. It was obvious that the concentrations of some uncommon contaminants, such as Sb and Sn, were higher than principal contaminants, such as Ni, Cu, Zn and Pb, suggesting that particular attention should be directed to Sn and Sb contamination in the future research of heavy metals in soils from e-waste-processing areas. Correlation analysis suggested that Li and Be in soils from the acid-leaching area and its surrounding environment might have originated from other industrial activities and from batteries, whereas Ni, Cu, Zn, Cd, Pb, Sn and Sb contamination was most likely caused by uncontrolled electronic waste (e-waste) processing. These results indicate the significant need for optimisation of e-waste-dismantling technologies and remediation of polluted soil

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

Science.gov (United States)

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.

Treatment of Petroleum Sludge By Using Solidification/Stabilization (S/S) Method : Effect of Hydration Days to Heavy Metals Leaching and Strength

Science.gov (United States)

Murshid, N.; Kamil, N. A. F. M.; Kadir, A. A.

2018-04-01

Petroleum sludge is one of the major solid wastes generated in the petroleum industry. Generally, there are numbers of heavy metals in petroleum sludge and one treatment that is gaining prominence to treat a variety of mixed organic and inorganic waste is solidification/stabilization (S/S) method. The treatment protects human health and the environment by immobilizing contaminants within the treated material and prevents migration of the contaminants. In this study, solidification/stabilization (S/S) method has been used to treat the petroleum sludge. The comparison of hydration days, namely, 7th and 28th days in these cement-based waste materials were studied by using Synthetic Precipitate Leaching Procedure (SPLP). The results were compared to the United States Environmental Protection Agency (USEPA) standards. The results for leaching test concluded that less percentage OPC gave maximum concentration of heavy metals leaching due to deficient in Calcium Oxide (CaO), which is can caused weak solidification in the mixture. Physical and mechanical properties conducted such as compressive strength and density test. From the results, it shows addition up to of 30percentage PS give results which comply with minimum landfill dispose limit. The results shows correlation between strength and density are strong regression coefficient of 82.7%. In conclusion, S/S method can be alternative disposal method for PS in the same time complies with standard for minimum landfill disposal limit. The results for leaching test concluded the less OPC percentage gave maximum concentration of heavy metals leaching.

Metal coordination in the high-temperature leaching of roasted NdFeB magnets with the ionic liquid betainium bis(trifluoromethylsulfonyl)imide

OpenAIRE

Orefice, Martina; Binnemans, Koen; Vander Hoogerstraete, Tom

2018-01-01

Ionic liquids are largely used to leach metals from primary (ores) and secondary sources (end-of-life products). However, dry ionic liquids with a carboxylic function on the cation have not yet been used to leach metals at temperature above 100 °C and under atmospheric pressure. The ionic liquid betainium bis(trifluoromethylsulfonyl)imide, [Hbet][Tf2N], was used in the dry state to recover neodymium, dysprosium and cobalt from NdFeB magnets and NdFeB production scrap. The magnets and the scra...

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

Science.gov (United States)

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

2013-11-01

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

Immobilization of heavy metals on pillared montmorillonite with a grafted chelate ligand

International Nuclear Information System (INIS)

Brown, Loren; Seaton, Kenneth; Mohseni, Ray; Vasiliev, Aleksey

2013-01-01

Highlights: • Mesoporous organoclay for immobilization of heavy metal cations was obtained. • The material has a porous structure with high contents of surface adsorption sites. • Leaching of heavy metals from soil reduced in the presence of this adsorbent. • The adsorbent demonstrated high effectiveness in neutral and acidic media. -- Abstract: The objective of this work was the development of an efficient adsorbent for irreversible immobilization of heavy metals in contaminated soils. The adsorbent was prepared by pillaring of montmorillonite with silica followed by grafting of a chelate ligand on its surface. Obtained adsorbent was mesoporous with high content of adsorption sites. Its structure was studied by BET adsorption of N 2 , dynamic light scattering, and scanning electron microscopy. The adsorption capacity of the organoclay was measured by its mixing with contaminated kaolin and soil samples and by analysis of heavy metal contents in leachate. Deionized water and 50% acetic acid were used for leaching of metals from the samples. As it was demonstrated by the experiments, the adsorbent was efficient in immobilization of heavy metals not only in neutral aqueous media but also in the presence of weak acid. As a result, the adsorbent can be used for reduction of heavy metal leaching from contaminated sites

Selection of lixiviant System for the alkaline in-situ Leaching of uranium from an arkosic type of sandstone and measuring the dissolution behaviour of some metals and non-metals

International Nuclear Information System (INIS)

Khan, Y.; Shah, S.S.; Siddiq, M.

2012-01-01

A laboratory simulation study was carried out to check the possibility of alkaline in-situ leaching of uranium from an arkosic type of sandstone recovered from a specific location at a depth of 300-500 m. The ore body was overlaying impervious clay shale below the water table. Different CO/sub 3/ containing soluble salts were tested as complexing agent of the UO/sup +2/ ions along with H/sub 2/O/sub 2/ as oxidizing agent. The lixiviant system, comprising NH/sub 4/HCO/sub 3/ as complexing agent along with H/Sub 2/O/sub 2/ as oxidizing agent in concentrations of 5 g/L and 0.5 g/L respectively, was found to be the most efficient for the leaching of uranium among the 25 different compositions employed. Along with uranium, the dissolution behaviour of 15 other metals, non-metals and radicals, including eight transition metals, was also observed in the lixiviant employed. These were Na, K, Ca, Mg, Cl, SO/sub 4/, CO/sub 3/, Ti, V, Cr, Mn, Fe, Cu, Zn and Mo. It was found that the leaching of uranium compared to non-transition et als/radicals followed the trend Cl > SO > U > Na > K > Mg > Ca > CO. The comparison of uranium leaching to the transition metals was in the order U > Cr > Mo > V > Ti > Cu > Zn > Mn > Fe. Physical parameters like pH, oxidation reduction potential (ORP) and conductivity were also measured for the fresh and pregnant lixiviants. It was found that the leaching of uranium is directly related to the concentration of native soluble hexavalent uranium, contact time of the lixiviant and ore and to some extent with the total concentration of uranium as well as the porosity and permeability of the ore. (author)

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

International Nuclear Information System (INIS)

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)

Uranium recovery from slags of metallic uranium

International Nuclear Information System (INIS)

Fornarolo, F.; Frajndlich, E.U.C.; Durazzo, M.

2006-01-01

The Center of the Nuclear Fuel of the Institute of Nuclear Energy Research - IPEN finished the program of attainment of fuel development for research reactors the base of Uranium Scilicet (U 3 Si 2 ) from Hexafluoride of Uranium (UF 6 ) with enrichment 20% in weight of 235 U. In the process of attainment of the league of U 3 Si 2 we have as Uranium intermediate product the metallic one whose attainment generates a slag contend Uranium. The present work shows the results gotten in the process of recovery of Uranium in slags of calcined slags of Uranium metallic. Uranium the metallic one is unstable, pyrophoricity and extremely reactive, whereas the U 3 O 8 is a steady oxide of low chemical reactivity, what it justifies the process of calcination of slags of Uranium metallic. The calcination of the Uranium slag of the metallic one in oxygen presence reduces Uranium metallic the U 3 O 8 . Experiments had been developed varying it of acid for Uranium control and excess, nitric molar concentration gram with regard to the stoichiometric leaching reaction of temperature of the leaching process. The 96,0% income proves the viability of the recovery process of slags of Uranium metallic, adopting it previous calcination of these slags in nitric way with low acid concentration and low temperature of leaching. (author)

LEACHING BOUNDARY IN CEMENT-BASED WASTE FORMS

Science.gov (United States)

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...

Biotechnical leaching of lean ores using heterotrophic microorganisms

International Nuclear Information System (INIS)

Schwartz, W.; Naeveke, R.

1980-01-01

After reporting briefly on leaching with Thiobacillus, it is discussed whether in those cases where thiobacilli fail to work the limits of microbial leaching are reached or still other groups of microorganisms will be suitable. In this relation the great number of carbon-heterotrophic fungi and bacteria have to be considered which are partly oligotrophic and occur e.g. in weathering biotopes of rocks and minerals and which may even include heavy metals in the dissolving processes of weathering. The active agents are, as far as is known up to now, organic acids which are produced by microorganisms and given off to the medium where they may combine with metals to form water-soluble complex compounds. In order to detect and isolate suitable strains of fungi and bacteria it will be necessary to work out a screening program which proceeds from general to special selections. Experiments to identify the active agents and the conditions of their production will have to follow. It remains still an open question whether such studies will result in technical processes. Mass production processes which are possible with the carbon-autotrophic and acidophilic thiobacilli are less probable than special processes to get hold of rare and economically valuable metals whose extraction would be difficult by other means. (orig.) [de

Remediation of hazardous waste sites by heap leaching

International Nuclear Information System (INIS)

Samani, Z.; Hanson, A.; Dwyer, B.

1994-01-01

Efforts are being made to devise technologies and treatment systems to remediate contaminated soil-on site without generating significant wastes for off-site disposal. Heap leaching, a technique used extensively in the mining industry, has been investigated as a method for remediation of hazardous chemical contamination of the vadose zone. In the mining industry, metal-bearing ore is excavated and mounded on a pad. The metals are removed by passing a special leaching solution through the ore. In this study, the removal of chromium(VI) from the New Mexico soils (sand, sandy loam, and clay) using heap leaching was evaluated at a column scale. The heap leaching study demonstrated greater than 99% removal of Cr(VI) from all three soils using tap water as the leaching agent. (author) 13 figs., 5 tabs., 21 refs

Extraction of toxic and valuable metals from wastewater sludge and ash arising from RECICLAGUA, a treatment plant for residual waters applying the leaching technique

International Nuclear Information System (INIS)

Guerrero D, J.J.

2004-01-01

Presently work, the technique is applied of having leached using coupled thermostatted columns, the X-ray diffraction for the identification of the atomic and molecular structure of the metals toxic that are present in the residual muds of a treatment plant of water located in the municipality of the Estado de Mexico, RECICLAGUA, likewise the techniques is used of Inductively Coupled Plasma Mass Spectroscopy and X-ray fluorescence analysis for the qualitative analysis. We took samples of residual sludge and incinerated ash of a treatment plant waste water from the industrial corridor Toluca-Lerma RECICLAGUA, located in Lerma, Estado de Mexico. For this study 100 g. of residual of sludge mixed with a solution to 10% of mineral acid or sodium hydroxide according to the case, to adjust the one p H at 2, 5, 7 and 10, bisulfite was added, of 0.3-1.5 g of dodecyl sulfate of sodium and 3.93 g of DTPA (triple V). Diethylene triamine penta acetate. These sludges and ashes were extracted from toxic and valuable metals by means of the leaching technique using coupled thermostated columns that which were designed by Dr. Jaime Vite Torres, it is necessary to make mention that so much the process as the apparatus with those that one worked was patented by him same. With the extraction of these metals, benefits are obtained, mainly of economic type, achieving the decrease of the volume of those wastes that have been generated; as well as the so much use of those residuals, once the metals have been eliminated, as of those residuals, once the metals have been eliminated, as of those liquors, the heavy metals were extracted. It was carried out a quantitative analysis using Icp mass spectroscopy, this way to be able to know the one content of the present metals in the samples before and after of leaching them, these results reported a great quantity of elements. Another of the techniques employees was the analysis by X-ray diffraction that provides an elementary content of the

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

Science.gov (United States)

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.

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

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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.

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

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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

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

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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.

Current practices in corrosion, surface characterization, and nickel leach testing of cardiovascular metallic implants.

Science.gov (United States)

Nagaraja, Srinidhi; Di Prima, Matthew; Saylor, David; Takai, Erica

2017-08-01

In an effort to better understand current test practices and improve nonclinical testing of cardiovascular metallic implants, the Food and Drug Administration (FDA) held a public workshop on Cardiovascular Metallic Implants: corrosion, surface characterization, and nickel leaching. The following topics were discussed: (1) methods used for corrosion assessments, surface characterization techniques, and nickel leach testing of metallic cardiovascular implant devices, (2) the limitations of each of these in vitro tests in predicting in vivo performance, (3) the need, utility, and circumstances when each test should be considered, and (4) the potential testing paradigms, including acceptance criteria for each test. In addition to the above topics, best practices for these various tests were discussed, and knowledge gaps were identified. Prior to the workshop, discussants had the option to provide feedback and information on issues relating to each of the topics via a voluntary preworkshop assignment. During the workshop, the pooled responses were presented and a panel of experts discussed the results. This article summarizes the proceedings of this workshop and background information provided by workshop participants. Published 2016. This article is a U.S. Government work and is in the public domain in the USA. J Biomed Mater Res Part B: Appl Biomater, 105B: 1330-1341, 2017. Published 2016. This article is a U.S. Government work and is in the public domain in the USA.

Leaching of vanadium from sulphuric acid manufacture spent catalysts

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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

Rare earth element recycling from waste nickel-metal hydride batteries.

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Yang, Xiuli; Zhang, Junwei; Fang, Xihui

2014-08-30

With an increase in number of waste nickel-metal hydride batteries, and because of the importance of rare earth elements, the recycling of rare earth elements is becoming increasingly important. In this paper, we investigate the effects of temperature, hydrochloric acid concentration, and leaching time to optimize leaching conditions and determine leach kinetics. The results indicate that an increase in temperature, hydrochloric acid concentration, and leaching time enhance the leaching rate of rare earth elements. A maximum rare earth elements recovery of 95.16% was achieved at optimal leaching conditions of 70°C, solid/liquid ratio of 1:10, 20% hydrochloric acid concentration, -74μm particle size, and 100min leaching time. The experimental data were best fitted by a chemical reaction-controlled model. The activation energy was 43.98kJ/mol and the reaction order for hydrochloric acid concentration was 0.64. The kinetic equation for the leaching process was found to be: 1-(1-x)(1/3)=A/ρr0[HCl](0.64)exp-439,8008.314Tt. After leaching and filtration, by adding saturated oxalic solution to the filtrate, rare earth element oxalates were obtained. After removing impurities by adding ammonia, filtering, washing with dilute hydrochloric acid, and calcining at 810°C, a final product of 99% pure rare earth oxides was obtained. Copyright © 2014 Elsevier B.V. All rights reserved.

[Bioregeneration of the solutions obtained during the leaching of nonferrous metals from waste slag by acidophilic microorganisms].

Science.gov (United States)

Fomchenko, N V; Murav'ev, M I; Kondrat'eva, T F

2014-01-01

The bioregeneration of the solutions obtained after the leaching of copper and zinc from waste slag by sulfuric solutions of ferric sulfate is examined. For bioregeneration, associations of mesophilic and moderately thermqophilic acidophilic chemolithotrophic microorganisms were made. It has been shown that the complete oxidation of iron ions in solutions obtained after the leaching of nonferrous metals from waste slag is possible at a dilution of the pregnant solution with a nutrient medium. It has been found that the maximal rate of oxidation of iron ions is observed at the use of a mesophilic association of microorganisms at a threefold dilution of the pregnant solution with a nutrient medium. The application ofbioregeneration during the production of nonferrous metals from both waste and converter slags would make it possible to approach the technology of their processing using the closed cycle of workflows.

Aqueous-chlorine leaching of typical Canadian uranium ores

International Nuclear Information System (INIS)

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.)

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

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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.

Leaching of gallium from gaiter granite, eastern desert, Egypt

International Nuclear Information System (INIS)

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

Stability and leaching of cobalt smelter fly ash