Bioleaching/ Bacterial Leaching

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Influence of Ferric and Ferrous Iron on Chemical and Bacterial Leaching of Copper Flotation Concentrates

Influence of Ferric and Ferrous Iron on Chemical and Bacterial Leaching of Copper Flotation Concentrates

In order to determine the influence of ferrous and ferric iron addition on the bioleaching of the copper concen- trate, shake flasks experiments were carried out in the presence and absence of 0.1 M of the mentioned cations. These experiments were carried out in 500 ml-Erlen- meyer flasks containing 200 ml of suspension of the concentrate at a pulp density of 10% (w/v) in the modi- fied Norris’s medium supplemented with 0.02% (w/v) yeast extract and having an initial pH of 1.5. Each flask was inoculated with a bacterial suspension (20% v/v) and then incubated at 50˚C and 150 rpm on a rotary shaker. To inoculate bacteria to a fresh medium, the bacterial solution was added to an Erlenmeyer flask containing the required fresh nutrient solution (at the desired pH). Then, the desired amount of concentrate and ferric and/or fer- rous iron when necessary, was added to the flask. After mixing the resulting slurry, the pH was regulated and the redox potential was recorded. These biotic experiments were inoculated with an active culture (as solution) with the cell density of about 2.7 × 10 8 cells/ml, which had been previously adapted to a 10% pulp density of the concentrate.
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Bioleaching as Possible Method of Sorbent Regeneration

Bioleaching as Possible Method of Sorbent Regeneration

based essentially on the ability of bacteria to oxidize ferrous iron i.e. to generate ferric iron within the leaching environment. The simple laboratory bioleaching experiment for iron removal with heterotrophic bacteria on natural raw materials was conducted to explore a simple cyclic operation for potential use at the industrial scale. Heterotrophic bacteria growing in the presence feldspar raw materials were able to dissolve iron. The bioleaching process involved acid attack, resulting in the solubilization of Si from the silicate phases and release impregnated particles of iron minerals from silicate matrix [12]. The dissolution of iron from quartz sands by basin bioleaching under the static in-situ condition pointed at the possibility to improve the quality of quartz sand used for the glass industry. The bacterial activity was dependent and varied with the environmental conditions, addition of chelators and organic feedstock in the form of glucose [13]. The bacteria related to the B. cereus species and indigenous heterotrophic bacteria were studied in the bioleaching of fine-grained fraction obtained from industrial washing of quartz sands. Their activity was evaluated by the changes in chemical composition of the fine fractions before and after the reaction process. The bacteria assisted in releasing of the poorly ordered clay minerals from the surface of quartz particles via dissolution of amorphous Fe oxyhydroxides [14]. The bacterial leaching of Zn (II), Ni(II) and Fe(III) from the contaminated sediments using heterotrophic bacterial strains was also studied by Jablonovská et al. [15].
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Bioleaching of Complex Sulfides Concentrate and Correlation of Leaching Parameters Using Multivariate Data Analysis Technique

Bioleaching of Complex Sulfides Concentrate and Correlation of Leaching Parameters Using Multivariate Data Analysis Technique

Bacterial leaching was applied to recover metal values from complex sulfide concentrates. The leaching kinetics were observed to depend on various leaching parameters, including Fe(II) concentration, pH and pulp density. The rate of leaching decreased with increase of iron precipitation rate. The leaching results indicated good bacterial activity. A Principle Component Analysis showed all the variables can be classified into four groups which account for more than 79.7% of the variance. The four groups were described as factors like leaching kinetics, bacterial activity, leaching parameters and bacterial metabolites. [doi:10.2320/matertrans.M2009125]
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Column bioleaching of sandstone type uranium ore deposit

Column bioleaching of sandstone type uranium ore deposit

Bioleaching has been successfully applied to heap leaching, tank leaching and in-situ leaching of low grade ores. In early 1960s, remarkable economic benefits were achieved by carrying out bacterial in situ leaching in some mines of Lake Eliot, Canada [1], Spain [2], Russia [3] and Japan also carried out study on bioleaching and successfully applied the technology of bioleaching to the treatment of uranium, gold and copper ores and wastewater. Uranium mine in Hunan province is the earliest one in China to apply bio leaching technology. During 1965-1971, the Institute of Microbiology of the Chinese Academy of Sciences and the former five locations of nuclear industry carried out heap leaching research on surface ore with acid and bacteria [4]. In the early 1990s, the Institute of Uranium Mining of nuclear industry carried out indoor bacterial leaching experiments on uranium ore and studied the in situ bacterial leaching of low grade crushed ore of mining site.
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Kinetics of Iron Bioleaching using Isolated Leptospirillum Ferriphilum: Effect of Temperature

Kinetics of Iron Bioleaching using Isolated Leptospirillum Ferriphilum: Effect of Temperature

Dr. Venkatesa Prabhu. S received Doctoral Degree in Faculty of Technology in Chemical Engineering specialization from Anna University, Chennai, India and he is having 18 years of Engineering teaching experience, currently teaching Chemical Engineering – Masters Level and PhD of courses at Addis Ababa Science and Technology University, Addis Ababa, Ethiopia. His professional interests focus on Environmental, Biochemical, Food process Engineering, and Enzyme Technology. At present, he is working on the research projects “Process Optimization and Kinetic Studies on Bacterial Leaching of Chromium from Tannery Sludge”, and “Investigation of Extraction Techniques for Recovery of Collagen from Tannery Raw Trimming Wastes”. He has published 21 reputed research publications. In addition, he serves as referee for the journals for The Journal of Cleaner Production,
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A Prelimary Molecular Approach for Characterizing Microorganisms Having the Potentials for Bioleaching of Iron Ore

A Prelimary Molecular Approach for Characterizing Microorganisms Having the Potentials for Bioleaching of Iron Ore

treating metallic ores or removing contaminants from metallic ores or industrial wastes and using molecular techniques to characterize microbial communities from mining sites have been developed for different metallic mineral resources.The aim of thispresent work was to determine the bioleaching capabilities of some pure and mixed consortium of three isolated bacterial species from Agbaja Mining site of Kogi state Nigeria and investigate the quality and quantity of their DNA with a view to finding their suitability for further molecular characterization.

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Bioleaching kinetics of chalcopyrite concentrate using leptospirillum ferriphilum: effect of silver ion

Bioleaching kinetics of chalcopyrite concentrate using leptospirillum ferriphilum: effect of silver ion

Copper is the second largest metallic chemical element widely used in the world. It is a ductile metal that conducts heat and is resistant to corrosion. This results in the usage of copper as a material of choice in various domestic, industrial, and high- technology applications. The world’s production and consumption of copper have increased dramatically in the past 25 years. Copper is obtained from different ore deposits such as chalcopyrite, chalcocite, covellite, bornite, tetrahedrite, cuprite, tennantite, azurite, and malachite. Of these, chalcopyrite is one of the most important sulfide minerals of copper [1,2]. Generally, copper is extracted by pressure hydrometallurgy process; otherwise, it is treated via flotation concentration followed by smelting [3]. This method has several disadvantages such as more chemical usage and high cost, and has also several environmental restrictions. To overcome these problems, the copper industry has moved toward biohydrometallurgical processes. Bioleaching is a technique of biohydrometallurgical processes by which dissolution of minerals due to direct or indirect action of microorganisms takes place [4]. Dissolution of minerals occurs due to the microbial oxidation of insoluble metal sulfides to soluble metal sulfates. This method has many potential advantages over conventional metal extraction techniques because it can be applied to all ore grades and to waste materials produced by conventional ore dressing. In addition, it is an environmentally sound technique as it does not give raise to atmospheric pollution and also requires very low energy.
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Optimizing of Iron Bioleaching from a Contaminated Kaolin Clay by the Use of Artificial Neural Network

Optimizing of Iron Bioleaching from a Contaminated Kaolin Clay by the Use of Artificial Neural Network

Iron oxides are class of undesirable impurities in kaolin mineral that decrease the brightness and quality of kaolin. Many methods such as magnetic separation, froth flotation, applications of potent reductants (for instance dithionite and hydrazine), selective flocculation, size separation by hydrocyclones, and leaching were utilized for the removal of iron oxides from kaolin and subsequently improving the clay quality. But, the efficiency of Iron removal in the mentioned methods is low [1]. Bioleaching is one of the most promising methods that were applied for iron removal from the kaolin. In comparison with the aforementioned methods, bioleaching has higher Iron removal efficiency, lesser environmental problems, lower energy and operating cost. In fact, microorganism can accelerate aluminosilicate mineral weathering reactions in direct contact with their surfaces, by producing organic and inorganic acids, creating metal- complex ligands, changing the redox condition or mediating the formation of secondary mineral phases. Several statistical methods have been applied to optimize this process [1, 2].
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Isolation and selection for edible mushroom production by liquid fermentation as laccase bioleaching sago starch

Isolation and selection for edible mushroom production by liquid fermentation as laccase bioleaching sago starch

Furthermore, Osma et al (2010) reported laccase can be promoted to control odors, improve taste and reduce the by- products (polyphenol compounds) that are not desired in some food products. Laccase is also used to reduce the bitter taste, improve the quality of the aroma and taste of chocolate based products and relieve unpopular in chocolate and enhance the flavor of the soybean oil product by removing the polyphenol compounds, improve the quality of aroma oils of plants by removing dissolved oxygen to prevent oxidation. Laccase can have new functionality, to improve quality, or lower production costs due to the reactivity of the components of food-related compounds such as carbohydrates, unsaturated fatty acids, phenol compounds and thiol-containing proteins. Some of them Suberzyme laccase formula and Flavoustar, used in the beer industry to eliminate polyphenol thereby extending the shelf life (Taylor & Francis, 2014). This study will perform the isolation and selection of edible mushroom fungus to produce laccase bioleaching sago. The purpose of this study is to obtain microbial laccase used to bioleaching sago starch and see the resulting enzyme activity.
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A Fuzzy Logic Model to Predict the Bioleaching Efficiency of Copper Concentrates in Stirred Tank Reactors

A Fuzzy Logic Model to Predict the Bioleaching Efficiency of Copper Concentrates in Stirred Tank Reactors

Multiplicity of the chemical, biological, electrochemical and operational variables and nonlinear behavior of metal extraction in bioleaching environments complicate the mathematical modeling of these systems. This research was done to predict copper and iron recovery from a copper flota- tion concentrate in a stirred tank bioreactor using a fuzzy logic model. Experiments were carried out in the presence of a mixed culture of mesophilic bacteria at 35˚C, and a mixed culture of mod- erately thermophilic bacteria at 50˚C. Input variables were method of operation (bioleaching or electrobioleaching), the type of bacteria and time (day), while the recoveries of copper and iron were the outputs. A relationship was developed between stated inputs and the outputs by means of “if-then” rules. The resulting fuzzy model showed a satisfactory prediction of the copper and iron extraction and had a good correlation of experimental data with R-squared more than 0.97. The results of this study suggested that fuzzy logic provided a powerful and reliable tool for pre- dicting the nonlinear and time variant bioleaching processes.
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Bioleaching Of Zinc And Iron From Sphalerite Using Leptospirillum Ferriphilum: Kinetic Aspects

Bioleaching Of Zinc And Iron From Sphalerite Using Leptospirillum Ferriphilum: Kinetic Aspects

Based on SCM, the rate controlling steps engaged with the fluid–particle reaction, for example, ash layer dispersion control and chemical reaction control were inspected. The graphical applicability of the SCM for bioleaching reaction is given in Fig. 6(a) and 6(b) for zinc and Fig. 7(b) and 7(b) for iron. The regression analysis from fitting of models plainly demonstrated that ash layer diffusion controlled SCM fits better to the observed bioleaching data. The rate-controlling factor of the indirect bioleaching is the dissemination of lixiviant through the ferric sulfate and the passive layer of elemental sulfur (product obtained according to 4) formed on the surface of sulfide minerals. The SEM images of raw ore and bioleached ore are depicted in Fig. 8 and 9. The SEM image of bioleached residue clearly shows the formation of elemental sulfur layer on the mineral surface by the biological reaction. This layer, which acts as diffusion barrier to mineral oxidation, likely controls the metal dissolution reaction.
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The optimization of Cu and Fe bioleaching from converter slag using Acidithiobacilus ferrooxidans

The optimization of Cu and Fe bioleaching from converter slag using Acidithiobacilus ferrooxidans

of Fe and Cu reached 95% and 100%, respectively. Modeling of experimental data suggested that both diffusion and chemical reaction were rate controlling in the bioleaching process. The comparison between bioleaching at optimum conditions and abiotic chemical leaching showed that bioleaching improved the recovery of Fe by 26% and the recovery of Cu by 33% due to acid production by At. ferrooxidans.

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TO STUDY THE LEACHING BEHAVIOR OF COAL ASH

TO STUDY THE LEACHING BEHAVIOR OF COAL ASH

The present study was undertaken to evaluate the leaching behavior around eklahare thermal power plant coal ash pond. For this purpose, long term leaching study was conducted to understand leaching pattern with respect to trace toxic elements by column leach test. Leachates from the column set up were also regularly monitored weekly and determine the relationship between leaching behavior with the properties of soil and coal ash.

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REVIEW ON HEAP LEACHING OF COPPER ORES

REVIEW ON HEAP LEACHING OF COPPER ORES

irrigation pulse, according to acid availability in the next irrigation solutions. * In the permanent precipitation of jarosites, ions from[r]

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Effects of Fe3+ and Ag+ on Column Bioleaching of a Low-grade Sulfide Copper Ore

Effects of Fe3+ and Ag+ on Column Bioleaching of a Low-grade Sulfide Copper Ore

Bioleaching is one of the effective ways to extract valuable minerals from solid wastes, complex polymetallic ores, and low-grade ores [5-7]. Additionally, it has been used to successfully treat low- grade copper ores. Chalcopyrite is an important copper resources. The bioleaching of high-grade chalcopyrite, including the bioleaching mechanisms and the influence of metal ions, has been widely researched. [10-13][1,7,14]. However, the leaching efficiency of the chalcopyrite can be severely deteriorated by the passive film formed during the bioleaching [8,9]. The problems of long a leaching cycle and a low leaching rate are still unsolved. Therefore, it is essential to explore feasible solutions to enhance the bioleaching efficiency of the chalcopyrite to broaden applications of bioleaching and enhance the utilization of the low-grade ores.
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New Sulphur Oxidizing Bacteria Isolated from Bioleaching Pulp of Zinc and Copper Concentrates

New Sulphur Oxidizing Bacteria Isolated from Bioleaching Pulp of Zinc and Copper Concentrates

Experiments on bioleaching of zinc and copper concentrates were performed in the periodic regime. Samples of the concentrate were disintegrated to particles 0.045 mm in size. Loads of disintegrated samples were placed into Ehrlenmeyer’s flasks (250 ml volume), moistened with water, and sterilized at 0.5 atm for 30 min. Then, the flasks were filled with 50 ml of 9K medium (acidated to pH 2.0) without iron, and bacterial association (5%) was introduced. Intensity of concentrate desalinization was assessed on the amount of desalinized copper, zinc, and iron as well as on reduction of pH of the medium and on titer increase for sulphur and iron oxidizing bacteria.
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The Design Of Water Flow System For Leaching Process

The Design Of Water Flow System For Leaching Process

Leaching generally known as a process to dissolves any unwanted elements in a solution. It is also comes in different kinds and shapes. Leaching process can be in fluid, gas or solid form of matter. Normally, this kind of process has been applied in water treatment industry. Nata de’ coco industry applying the leaching process for nata neutralization. After fermentation of nata, the value of pointer Hydrogen (pH) in nata is 3.0 which not consumption. It has a bad smell because it is contains of acetic acid. Leaching process is using to can remove the smell or acetic acid molecules. So it must be neutralizing up to pH 7.0 by using water as the medium for neutralization with a long period. The water needs to be replaced regularly during the leaching process.
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Preliminary Bioleaching of Heavy Metals from Contaminated Soil Applying Aspergillus niger F2

Preliminary Bioleaching of Heavy Metals from Contaminated Soil Applying Aspergillus niger F2

When the sucrose was used as carbon source (Table 2), bioleaching percentages of Cd, Cu, Pb, and Zn are 35.89%, 48.19%, 100%, and 70.86%, respectively. The bioleaching percentage of Cd, Cu, Pb, and Zn are 27.38%, 46.09%, 100%, and 67.49% when glucose as carbon source. The bioleaching percentage of Cd, Cu, Pb, and Zn are 25.53%, 46.87%, 100%, and 65.16% when maltose as carbon source. The bioleaching percentage of Cd, Cu, Pb, and Zn are 0.443%, 0.705%, 3.81%, and 0.77% lactose as carbon source. The bioleaching percentage of Cd, Cu, Pb, and Zn are 32.11%, 46.46%, 100%, and 70.15% when the starch as carbon source. The total heavy metal bioleaching of sucrose, glucose, maltose, lactose, and starch were 69.86%, 66.57%, 64.59%, 0.92%, and 69.01%, respectively. For Cd, Cu and Zn, the bioleaching percentage is the highest when using sucrose as carbon source. For Pb, all the bioleaching percentages are 100% except for using lactose as carbon source. The heavy metal bioleaching percentage of lactose is the lowest than any other carbon sources, while the heavy metal bioleaching percentage of sucrose is the highest than any other carbon sources. The effect of carbon source on bioleaching was very significant due to organic acids produced by F2 based on the oxidation of carbon sources.
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The role of catalyst in the passivation of chalcopyrite during leaching

The role of catalyst in the passivation of chalcopyrite during leaching

The chalcopyrite leaching reaction in this media is initially very rapid, but it decreases afterwards. It has been generally accepted that the main cause of low leaching efficiency of chalcopyrite in leaching process is formation of passivation layer which can inhibit the further dissolution of chalcopyrite [5, 6, 22]. The nature of these passivation layers has long been an argument. However, there are three different hypotheses to explain the structure of this impermeable layer. One theory suggests the formation of the sulfur layer which limits the oxidation reaction. Another hypothesis suggests the formation of a copper-rich polysulfide layer which develops on the surface, as a result of solid state changes to the mineral during leaching [7]. A third theory suggests that the passivation layer consists of iron salts [8]. Recently, it was found that in ferric sulfate media, adding pyrite to the system had performed as a catalyst and increased copper recovery. This process is Galvanox™[9]. It is strictly chemical and therefore requires no microbe. Fine grinding is not required in this process. Also, the operating temperature is low, and the chemical conditions are mild. When pyrite is present in the leach slurry, ferric reduction increases and this allows the system to maintain the solution potential within the active region of the mineral [10-13].
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Effect of Cardamom Extract on leaching of Aluminum Cookware

Effect of Cardamom Extract on leaching of Aluminum Cookware

This method was applied to estimate small changes of Al leaching using a galvanostat /potentiostat (from ACM). Two cells were used here. The first one was a three electrode cell where the working electrode was Pure Al (99.99%) with an exposed surface area of 0.20cm 2 . The second cell was a sample holder from Radiometer. The two Al cook wares were cut into circular disks of 1.4cm diameter and an exposed area of 1.13cm 2 . The Al disk (as the working electrode) was fitted into a thermo stated sample holder cell. For both cells, the reference electrode was saturated Calomel electrode (SCE) and the auxiliary electrode was Platinum. All electrochemical experiments were performed in aerated solutions and maintained at 60°C ±1 using a circulating water bath (from Haak). After performing open circuit potential for 1 hour, polarization measurements were done to obtain corrosion current density from Tafel method by scanning the potential, E ss ± 250 mv at a rate of 1
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