bacterial leaching process indirect procees
Bioleaching: A microbial process of metal recovery; A review
The present review describes the historical development and mechanisms of bioleaching, which has shown commercial application of the process and, concurrently, details pertaining to the key microorganisms involved in these processes have been described. The present review describes the historical development and mechanisms of …
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16.6A: Microbial Ore Leaching
The Leaching Process. Bacteria perform the key reaction of regenerating the major ore oxidizer which in most cases is ferric iron as well as further ore oxidation. The reaction is performed at the bacterial cell membrane. In the process, free electrons are generated and used for the reduction of oxygen to water which produces energy in the ...
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The Indirect Mechanism of Bacterial Leaching
The indirect mechanism of bacterial leaching, which is a combination of these two sub-processes, is able to account for the shape of the reaction curve obtained from bacterial leaching experiments. It is also shown that even at very low concentrations of iron in solution the indirect mechanism may be the dominant pathway in bacterial …
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Bioleaching
Direct and indirect mechanisms are involved in sulfur based leaching process by bacteria leading to the formation of metal sulfides and its dissolution (Fig. 4). In direct leaching process, bacteria directly contact and react with metal sulfide and oxidize it to soluble metal sulfates like NiS, ZnS, CuS, etc.
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Progress in bioleaching: fundamentals and mechanisms of
In general, leaching bacteria seem to grow attached to the surfaces of mineral sulfides. In case of not limiting surface space, some microorganisms with good attachment capabilities to mineral surfaces exhibit attachment of up to 80–90% of the planktonic cells within less than one day (Gehrke et al. 1998; Harneit et al. 2006).It is …
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Bacterial Leaching of Metal Sulfides Proceeds by Two Indirect
Recently, we described for pyrite (FeS 2) degradation an iron(III) ion-mediated leaching mechanism via thiosulfate and polythionates ().In this thiosulfate mechanism, the Fe-S 2 bond is cleaved, after the S 2 group has been oxidized by iron(III) hexahydrate ions to a thiosulfate group. Hydrolysis yields thiosulfate and an iron(II) ion. Thiosulfate is …
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Direct versus indirect bioleaching
1.. IntroductionThe mechanism of bacterial leaching of sulfides has interested researchers for a long time [1], [2].While many parameters affecting the leaching process have been known as empirical factors, a more profound understanding of the heterogeneous mechanism of sulfide degradation has only gradually emerged as a …
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Bacterial Leaching of Metal Sulfides Proceeds by Two Indirect
The acid-insoluble metal sulfides FeS 2, MoS2, and WS2 are chemically attacked by iron(III) hexahydrate ions, generating thiosulfate, which is oxidized to sulfuric acid, explaining leaching of metal sulfide by Thiobacillus thiooxidans. ABSTRACT The acid-insoluble metal sulfides FeS2, MoS2, and WS2 are chemically attacked by iron(III) …
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Bacterial Leaching
is further confirmed by the leaching of synthetic sulphides free of iron, where only the direct attack of the bacteria can lead to leaching: CuS (covellite) + 202 --.CuS04, ZnS (sphalerite) + 20z -+ ZnS04 • Bacterial Leaching Techniques The two major techniques used in leaching are percolation and agitation leaching.
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Direct versus indirect bioleaching
Direct versus indirect bioleaching W. Sand, T. Gehrke, P.-G. Jozsa, and A. Schippers Universit~it Hamburg, Institut fitr Allgemeine Botanik, Abteilung Mikrobiologie, Ohnhorststrage 18, D-22609 Hamburg, Germany Phone/Fax: 040/82282-423, e-mail: [email protected] Bioleaching of metal sulfides is effected by bacteria like Thiobacillus …
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Direct versus indirect bioleaching
In practice, multiple patterns of bacterial leaching coexist, including indirect leaching, contact leaching and a recently discovered cooperative (symbiotic) leaching …
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Progress in bioleaching: fundamentals and mechanisms of …
For this process, the term bio-oxidation is used because the solubilized metals such as iron and arsenic are not of economic value. ... Schippers A. (Bio)chemistry of bacterial leaching – direct vs. indirect bioleaching. Hydrometallurgy. 2001; 59:159–175. [Google Scholar] Sanhueza A, Ferrer IJ, Vargas T, Amils R, Sánchez C. Attachment of ...
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Progress in bioleaching: fundamentals and mechanisms of …
Schippers A, Sand W. Bacterial leaching of metal sulfides proceeds by two indirect mechanisms via thiosulfate or via polysulfides and sulfur. Appl Environ …
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The microbial leaching process was evaluated for the treatment of synthetic sediments contaminated with cadmium and nickel sulfides to compare metal solubilization in sediment inoculated with Acidithiobacillus ferrooxidans -inoculated sediments to that in sterile control sediment, indicating that indirect non-contact leaching by the products of …
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(PDF) BIOLEACHING OF COPPER ORES AND CONCENTRATES …
Bacterial assisted leaching processes are based on the ability of certain microorganisms to solubilize/or expose the metals contained in the ores and concentrates by direct oxidation, or through ...
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Indirect in situ bioleaching is an emerging tool for accessing …
The unique hydrofracking-bioleaching in situ pilot plant applied indirect leaching of copper with ferric iron lixiviant, i.e., the acidophilic microorganisms were contained in a Ferric Iron Generating Bioreactor (FIGB) on site at 1 km depth, into which the reduced iron solution after Cu recovery was directed for reoxidation by an iron oxidizing ...
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Microbial leaching for valuable metals harvesting: versatility …
Mostly bacteria and fungi can be engaged for this purpose. The bacterial assisted microbial leaching is called "bacterial leaching" and the term "fungal leaching" is applied for microbial leaching supported by fungi. Figure 1 shows some of the most commonly used micro-organisms in the microbial leaching process. Depending upon …
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Bacterial Leaching of Metal Sulfides Proceeds by Two Indirect
Bacterial Leaching of Metal Sulfides Proceeds by Two Indirect Mechanisms via Thiosulfate or via Polysulfides and Sulfur Schippers, Axel; Sand, Wolfgang; Abstract. Publication: Applied and Environmental Microbiology. Pub Date: January 1999 DOI: 10.1128/AEM.65.1.319-321.1999 ...
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Bacterial leaching of metal sulfides proceeds by two indirect
Bacterial leaching, the biooxidation of metal sulfides to soluble metal sulfates and sulfuric acid, is effected by specialized bacteria. Three species of mesoacidophilic, chemolithotrophic bacteria are mainly involved: Thiobacillus ferrooxidans, Thiobacillus thiooxidans, and Leptospirillum ferrooxidans.T. ferrooxidans oxidizes reduced sulfur …
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Bioleaching of heavy metals from metal tailings utilizing bacteria …
Acidolysis is an indirect leaching process that has been described as the most rapid and prevalent mechanism of leaching by fungi, bacteria and other heterotrophic organisms. ... Altinkaya et al. (2018) used mixed acidophilic bacteria to leach low-grade tailings with extraction rates of 90%, 60%, 86% and 67% for Ni, Co, ...
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Mechanisms of bioleaching: iron and sulfur oxidation by …
During the bioleaching process, microbes generate energy by oxidising sulfur and iron from sulfide minerals. The resulting oxidants attack the sulfide minerals, …
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Decomposition
Leaching. The fragmented particles may contain a lot of water-soluble nutrients which are inorganic in nature. These nutrients get dissolved in the water and seep into the soil and get precipitated in the process of leaching. ... This process is carried out by various fungal and bacterial enzymes by the process of catabolism. Humification.
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Mechanisms of bioleaching: iron and sulfur oxidation by …
An additional process of 'cooperative leaching' has also been described, whereby some free-living bacteria oxidise sulfur species ... (Bio)chemistry of bacterial leaching - direct vs. indirect bioleaching. Hydrometallurgy 59, 159–175 10.1016/S0304-386X(00)00180-8 [Google Scholar] 63. Jones S. (2022) Prokaryotic Dissolution of ...
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(Bio)chemistry of bacterial leaching—direct vs. indirect …
The two different indirect oxidation mechanisms together with the role of the EPS have a fundamental importance for the debate about the "direct" or "indirect" …
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Bacterial leaching of metal sulfides proceeds by two indirect
The oxidation products in the case of FeS 2 and MoS 2 consisted of up to 90% sulfate and about 1 to 2% polythionates. Because the valence bands of FeS 2 and MoS 2 are derived only from the metal orbitals, the valence bands do not contribute to the chemical bond between the metal and the sulfur moiety in the crystal (2, …
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Sulfur chemistry in bacterial leaching of pyrite
The data indicate that thiosulfate, trithionate, tetrathionates, and disulfane-monosulfonic acid are key intermediate sulfur compounds in oxidative pyrite degradation, and a novel (cyclic) leaching mechanism is proposed which basically is indirect. In the case of pyrite bioleaching by Leptospirillum ferrooxidans, an organism without sulfur …
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Bio Hydrometallurgical Technology, Application and Process Enhancement
2. Mechanisms of bioleaching. The two majorly known mechanism in bacterial leaching are direct mechanism (involves physical contact of the organism with the insoluble sulphide) or hypothesized enzymatic reaction taking place between an attached cell and the underlying mineral surface which is independent of indirect …
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Indirect in situ Bioleaching is an Emerging Tool for …
– A Case Study of Copper Leaching at 1km Depth" by M. Bomberg et al. Semantic Scholar extracted view of "Indirect in situ Bioleaching is an Emerging Tool for Accessing Deeply Buried Metal Reserves, But Can the Process be Managed? – A Case Study of Copper Leaching at 1km Depth" by M. Bomberg et al.
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Bioleaching: metal solubilization by microorganisms
Microbial leaching methods are being increasingly applied for metal recovery from low-grade ores and concentrates that cannot be processed economically by conventional methods. As is the case with many …
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Bio Hydrometallurgical Technology, Application …
Bioleaching refers to the use of bacteria, the common Thiobacillus Ferrooxidans and other bacterial as a leachant to leach sulfide minerals where the target elements remains in the solution during …
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