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Investigation of the Effect of Oxidation/Reduction Potential on Chalcopyrite Bioleaching
Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
2019 (English)Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
Abstract [en]

The increasing metal demand in today’s society is a major factor behind the drive to develop the field of bioleaching, a cheap and effective technology which extracts metals from low grade ores. The world’s most abundant copper source, chalcopyrite (CuFeS2), is very difficult to process with bioleaching due to a phenomena called passivation. Many researchers across the globe work to improve the bioleaching of chalcopyrite for this very reason. One factor that has in previous studies been shown to increase the effect of the bioleaching mechanisms is the oxidation/reduction potential, or redox potential. In this study six different mineral-oxidizing bacterial cultures was tested and their pH, development of redox potential, Fe2+ concentration and the total concentrations of copper and iron leached by the cultures throughout the duration of the experiments was measured. The duration of the experiments varied for the cultures based on the time it took for their redox potentials to stabilize. The results indicate that the more efficient chalcopyrite bioleaching bacteria cultures were those which maintains a redox potential of >400 but <500 mV. Acidimicrobium ferrooxidans, Sulfobacillus acidophilus and Sulfobacillus thermosulfidooxidans was the most efficient bacterial strains used and kept their redox potential within the 400 to 500 mV range while Acidithiobacillus ferridurans and Acidithiobacillus ferriphilus were less efficient and their redox potential was kept at above 500 mV. These results also suggests a need for methods of managing the microbial populations in bioleaching heaps.

Abstract [sv]

Ökningen i efterfrågan på metaller i dagens samhälle är en stor anledning till drivkraften bakom utvecklandet av biourlakningsfältet, en billig och effektiv teknik som extraherar metaller ur lågkvalitetsmalmer. Världens mest rika kopparkälla, kopparkis (CuFeS2), är väldigt svår att biourlaka p.g.a. ett fenomen som kallas passivering. Många forskare över hela jorden arbetar för att förbättra biourlakningen av kopparkis av just denna anledning. En faktor som tidigare studier har visat en ökning av biourlakningsmekanismen är oxidation/reduktions-potentialen, eller redox-potentialen. I denna studie har sex olika biourlakande bakteriekulturer testats och deras pH, redox potential, Fe2+ koncentration och de totala koncentrationerna av koppar och järn vilka urlakats av de olika kulturerna genom experimentens varaktighet har mätts. Experimentens varaktighet varierade mellan kulturerna baserat på tiden det tog för deras redox potential att stabilisera sig. Resultatet indikerar att de mer effektiva kopparkis-biourlakar-bakteriakulturerna var de som kunde hålla en redox potential på >400 men <500 mV. Acidimicrobium ferrooxidans, Sulfobacillus acidophilus och Sulfobacillus thermosulfidooxidans var de mest effektiva bakteriekulturerna som användes och deras redox potential hölls inom 400 till 500 mV medan Acidithiobacillus ferridurans och Acidithiobacillus ferriphilus var mindre effektiva och deras redoxpotential hölls ovan 500 mV. Dessa resultat föreslår även att ett behov av metoder för att hantera mikroba populationer i biourlakningshögar existerar.

Place, publisher, year, edition, pages
2019. , p. 22
National Category
Microbiology
Identifiers
URN: urn:nbn:se:lnu:diva-90001OAI: oai:DiVA.org:lnu-90001DiVA, id: diva2:1369368
Subject / course
Biology
Educational program
Biology Programme, 180 credits
Presentation
2019-06-11, Magenta_Vi2144K, Norra kajplanen 6, Kalmar, 10:00 (English)
Supervisors
Examiners
Available from: 2019-11-13 Created: 2019-11-11 Last updated: 2019-11-13Bibliographically approved

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