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In this review, we summarize some recent discoveries relevant to leaching bacteria which contribute to a better understanding of these fascinating microorganisms. …
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Leaching Two principle mechanisms have been identified by which bacterial ac-tion can liberate copper and other bivalent metal ions from insoluble sul-fide ores. These are indirect and direct leaching. A third mechanism called galvanic conversion has been de-scribed but its contribution to metal leaching has not yet been conclusively demonstrated.
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The molecular mechanisms, which leaching bacteria use to adapt the composition and amount of their EPS to a new growth substrate (planktonic cells …
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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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Bacterial assisted leaching of scrap TV circuit boards was carried out for the recovery of copper using a mixed culture of mesophilic bacteria (comprising of At. ferrooxidans, L. ferrooxidans, At. thiooxidans) . The bioleaching process was seen to be dependent on ferrous iron oxidation efficiency of the bacteria and the initial availability of ...
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Bioleaching of metal sulfides is performed by a diverse group of microorganisms. The dissolution chemistry of metal sulfides follows two pathways, which are determined by the mineralogy and the acid solubility of the metal sulfides: the thiosulfate and the polysulfide pathways. Bacterial cells can effect this metal sulfide dissolution via …
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The aim of this study is to design and develop an efficient leaching process based on a fundamental and theoretical thermodynamic analysis and the optimization of the operation parameters via the response surface methodology (RSM). Using this methodology, the design of a leaching process for the recovery of copper, silver, and …
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From the heterotrophic genus of bacteria Thiobacillus and Pseudomonas are those used to leach non-sulfide minerals and from the genus of fungi Penicillium and Aspergillus (heterotrophic fungi) are those used in leaching process, a study shows 55–60% leaching rate for nickel and cobalt, some other studies indicates that 95% and …
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However, the above-mentioned anaerobic physiology of leaching bacteria and their presence in anoxic biotopes support the hypothesis of an anaerobic leaching process. For example, the existence of Acidithiobacillus -like species has been demonstrated in an anoxic reactor designed to clean contaminated groundwater and …
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to the exploration of the mechanism of biological leaching lies in microorganisms. Only by thoroughly studying the behavior of microorganisms in the leaching process can the mechanism of biological leaching be accurately and system-atically interpreted, which will also depend on developments in molecular biology and other disciplines. 2.1.2.
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Inoculating the bacterial community with ferric iron (Fe 3+) under shaking conditions resulted in rapid copper recovery from bornite, leaching 40% of the Cu content after 10 days of cultivation. The addition of ferrous iron (Fe 2+) instead promoted Cu recovery of 30% at day 48, clearly delaying the leaching process. More efficiently, the ...
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Methods in bioleaching are mainly classified as agitation leaching for fine particles and percolation leaching process for coarse particles ... Gholami RM, Borghei SM, Mousavi SM (2011) Bacterial leaching of a spent Mo-Co-Ni refinery catalyst using Acidithiobacillus ferrooxidans and Acidithiobacillus thiooxidans. Hydrometallurgy …
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Microbes applied for microbial leaching. A number of organisms can be engaged in microbial leaching of valuable metals out of contaminated soil and sediment, …
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The leaching parameters showed that native strains played excellent roles in their corresponding ore bioleaching process, and community structure was greatly determined by mineral composition, indicating that domestication for longitudinal adaption was an effective way to improve microbial leaching performance.
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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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Bioleaching is a simple and effective technology for metal extraction from low-grade ores and mineral concentrates. Metal recovery from sulfide minerals is based on the activity of chemolithotrophic bacteria, mainly Thiobacillus ferrooxidans and T. thiooxidans, which convert insoluble metal sulfides into soluble metal sulfates. Non-sulfide ores ...
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Tailings contain harmful quantities of toxic substances that can potentially pose serious health and environmental problems through air dispersion of air-dried …
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Bioleaching is a promising strategy to recover valuable metals from spent printed circuit boards (PCBs). The performance of the process is catalyzed by microorganisms, which the toxic effect of PCBs …
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Bioleaching is a microbial-driven process to solubilize the metal from its stable molecules. The major challenge of the bioleaching process is metal toxicity to applied microorganisms. Metal sources generally contain more than one metal and possess an inhibitory or antimicrobial effect on the applied microorganism.
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This includes the slow kinetics of the bacterial leaching process. Therefore, it is important develop catalyst to optimize the interactions of the microbes with the minerals while accelerating the kinetics. Also, most studies in respect to bioleaching of contaminated soil is limited to laboratory scale and hence accurate estimation for ...
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The application of biochar can affect soil properties and retention of fertilizer nitrogen, but its effects and mechanism on the retention capacity of different forms of nitrogen in soils are still uncertain. In this study, an indoor soil column leaching experiment was conducted using vegetable soil samples with 3% rice husk biochar by mass …
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The bacterial leaching using cultures G1 and G2 was studied in 500 ml glass bulbs with 200 ml of the PW30 nutrient medium that contained 10% (v/v) of ... The possibility of the recovery of iodine from the raffinate at the end of the leaching process also could be beneficial. IOB-based gold bioleaching is less toxic than traditional cyanide ...
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The leaching process was monitored by checking pH, ORP (oxidation-reduction potential) and ferrous iron concentration of the leachate solution periodically. ... Leaching with inorganic acids; Table S4: Bacterial leaching of PCBS varying pulp density; Table S5: Bacterial leaching of PCBS varying ferrous iron concentration; Table S6: …
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For bioleaching of gold ore concentrate with R. tolerans, triiodide concentrations were higher in one-step and two-step leaching than in the bacterial control (bacteria without ore concentrate) and spent medium leaching as shown in Figure 2 a. On the other hand, for bioleaching gold ore concentrate with R. mucosus, ...
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Using acidophilic bacteria to catalyze the reductive dissolution of oxidized minerals is an innovative process that facilitates the extraction of valuable base metals (principally cobalt and nickel) from limonites, which are otherwise often regarded as waste products of laterite mining. The most appropriate conditions required to optimize …
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colates through the pile, bacteria of the genus Thiobacillus, which are ubiquitous in such sulfidic rocks, proliferate. The bacteria great ly accelerate the leaching process by breaking down the sulfide min erals, converting ferrous iron into ferric iron and generating sulfuric acid. The ferric iron serves to oxidize the degraded sulfide ...
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The bacteria brought into the bioleaching environment from outside (for example, via unsterilized growth medium or the reagents) compete with the natural microbiome of the ore, and their effects should be assessed and considered. ... The amino acid-thiosulphate leaching process would be more appealing than cyanidation if a …
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At higher temperature (50–60 °C) thermophilic bacteria can be used for the leaching process. 13.8.6 O 2 and CO 2. An adequate amount of oxygen is required for the good growth and high activity of leaching bacteria. Oxygen can be provided by aerators and pipes. Mechanical agitation is also an effective method to provide continuous air …
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The molecular mechanisms, which leaching bacteria use to adapt the composition and amount of their EPS to a new growth substrate (planktonic cells grown …
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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 …
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