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Showing 1 to 20 of 49 for “"Bioleaching"”.
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Bioleaching of chalcopyrite
This research is concerned with the bioleaching of chalcopyrite (CuFeS\(_2\)) by Thiobacillus ferrooxidans (ATCC 19859), which has been carried out in shake flasks (250 ml) and a 4-litre stirred tank bioreactor. The effects of experimental factors such as initial pH, particle size, pulp density and …
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Microbial dynamics of bioleaching consortia
… and electronic wastes for metal retrieval. Bioleaching is considered a suitable method for metal recovery from these wastes. This is because of its perceived low cost, environmental astuteness and its ability to nullify the potential environmental degradation that can occur as a result of …
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Bioleaching and electrobioleaching of sulfide minerals
… sphalerite, and pyrite, were leached using a bioleaching mode and an electrobioleaching mode. The former mode was used to teach the minerals with the bacterium A. ferrooxidans in a bioreactor. In the latter mode, the leaching of the minerals was performed in a combination of a bioreactor and …
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Studies on the mechanism and kinetics of bioleaching with special reference to the bioleaching of refractory gold-bearing arsenopyrite
Bioleaching is now an established technology for the leaching of whole-ore copper heaps and the pre-treatment of refractory arsenical gold ores and concentrates. For the case of refractory arsenical gold concentrates, it offers an economically feasible alternative to pressure oxidation and has …
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Mathematical modelling of agglomerate scale phenomena in heap bioleaching
Bioleaching is a naturally occurring process that has been harnessed in metal recovery from low grade ores. The heap bioleaching technique involves complex interactions between chemical reactions, microbial processes and transport processes. The need for efficient heap operations has led to the …
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Electrochemical speciation and quantitative chromatography for modelling of indium bioleaching solutions
In order to meet increasing indium demands, (bio)hydrometallurgical winning of low-grade sources will likely be required. The goal of this work in the scope of the Biohydrometallurgical Centre Freiberg, was to use geochemical modelling to improve indium leaching and extraction efficiency. Indium …
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Geomycology: fungal bioweathering, bioleaching, bioprecipitation and biotransformation of metals and minerals
… has examined fungal roles in bioweathering and bioleaching of zinc sulfide ore, together with an investigation of the role of fungal phosphatases in the bioprecipitation of uranium and lead when utilising an organic phosphorus-containing substrate as the sole phosphorus source. The results …
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Comparison of gold extraction yields by cyanide treatment vs. bioleaching procedure
<p>Samples from the tailings of the Picacho mine in California were leached using NaCN and native bacteria, <em>Alcaligenes faecalis,</em> in column experiments to compare the gold recovery yields in the effluents. Four columns were treated with a different liquid: water, bacteria, NaCN and a …
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Potential of thermophilic bioleaching, effect of temperature on the process performance
Bioleaching is a biohydrometallurgical process whereby mineral sulphides are metabolically oxidised by microorganisms, releasing precious metals encapsulated in them. This pre-treatment is based on the action of microorganisms affecting oxidation of reduced sulphur species and ferrous iron to …
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Formation of thiocyanate in bioleaching residues and its effect in PGM recovery
A recent study investigated the feasibility of a sequential heap leach in low grade Platreef ore in order to recover PGMs (Platinum Group Metals), by a pure hydrometallurgical route. This method comprised of two stages, an initial thermophile bioleach stage to extract base metals followed by a …
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Effects of intermittent irrigation on the extraction of copper from heap bioleaching systems.
… from a low grade chalcopyrite ore in the heap bioleaching system is investigated and compared with the effect under abiotic conditions. As a secondary investigation, the effect of the introduction of layers of fines, which may develop during the course of the operation of heaps, on copper …
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An investigation into the mechanism of bioleaching of a predominantly-chalcopyrite concentrate with mesophiles
Bioleaching is an established technology for the treatment of refractory gold ores and concentrates. The bioleaching of sulphide minerals is a complex process in which bacterial and chemical oxidation processes occur simultaneously. Recent studies has provided convincing evidence that the …
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Recovery of rare earth elements (REE) from waste printed circuit boards (WPCBs) through heterotrophic bioleaching
… the extraction of REE from WPCBs through bioleaching and provide insights into the microbial mechanisms involved in the REE bioleaching process. Industrially comminuted WPCBs were provided by e-waste recycling companies from the UK. The chemical composition of the WPCBs material was …
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An investigation into the feasibility of bioleaching copper sulphide ore of Nchanga mine, Chingola, Zambia
Bioleaching is now well established for extraction of copper from its low-grade, mixed oxide/sulphide ores in bioheap operations (Watling, 2006). It is claimed bioleaching may be a cheaper alternative to other traditional metal extraction techniques such as smelting and therefore more suitable to …
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An investigation into the ferric leaching of chalcopyrite : a sub-process in the bioleaching of chalcopyrite
… to develop an understanding of the chalcopyrite bioleaching sub-processes. This thesis forms part of the greater study on bioleaching, investigating the ferric leaching subprocess. The objective of this thesis was two-folds. Firstly, a detailed literature review was undertaken to develop a better …
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The effect of particulate-induced hydrodynamic stress on the bioleaching of chalcopyrite by a Sulfolobus sp.
… study centres on slurry reactors utilised in the bioleaching industry. The micro-organisms employed in these processes include mesophilic micro-organisms and, more recently, thermophilic microbes which have shown much promise for improving the rate and extent of leaching particularly of …
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An investigation into the effect of solid particulate phase on the bioleaching performance of Sulfolobus metallicus
… of the valuable metal, may be carried out. Bioleaching of the mineral may be used as pretreatment. Further mineral bioleaching may be used to liberate base metals such as copper from refractory sulphidic ores. The microorganisms used in the high intensity tank-based commercial …
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Factors affecting the attachment of Metallosphaera hakonensis during the colonisation of low grade mineral sulphide heaps
… pertains to the extraction of copper via heap bioleaching, focussing specifically on the bioleaching of the mineral sulphide, chalcopyrite (CuFeS2). Industrial heap bioleaching offers an attractive alternative to conventional extraction methods, such as smelting, for processing low grade ores. …
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Biooxidation kinetics of Leptospirillum Ferriphilum attached to a defined solid substrate
Bioleaching can be categorized as being either stirred tank type (i.e. bio-oxidation) or irrigation type (i.e. heap/dump bioleaching) yet studies investigating the kinetics of bioleaching systems mostly use empirical data determined from stirred tank type and initial rate experiments in batch …
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