Metal sulphide precipitation : effect of operational parameters on particle characteristics and process efficiency

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dc.contributor.advisorLewis, Alison Emslieen_ZA
dc.contributor.advisorVan Hille, Rob
dc.contributor.authorMokone, Thebe Phillipen_ZA
dc.date.accessioned2015-07-14T08:48:10Z
dc.date.available2015-07-14T08:48:10Z
dc.date.issued2010en_ZA
dc.descriptionIncludes bibliographical references (p. 127-141).en_ZA
dc.description.abstractAcid mine drainage (AMD) is one of the major, long-term environmental challenges facing the minerals processing industry. Uncontrolled discharges have polluted thousands of kilometres of rivers, as well as surface and groundwater bodies with acidic effluents high in dissolved metals and sulphate. Conventional treatment technologies rely on oxidation, neutralisation and precipitation. While these may be effective they are expensive and not sustainable in the long term. Several biological treatment technologies, based on the activity of sulphate reducing bacteria (SRB), have been successfully developed and applied at both laboratory and industrial scale. The SRB uses sulphate as the terminal electron acceptor and with a suitable electron donor produce bicarbonate alkalinity and sulphide. These can be used to neutralise acidic effluents and effect precipitation of dissolved metal ions as metal sulphides. However, a number of challenges exist around the precipitation step, particularly where the recovery of valuable metals is desired. Metal sulphide precipitation reactions are inherently driven by extremely high levels of supersaturation. As a result, metal sulphide precipitation reactions are difficult to control and a large number of small particles are formed during the process. This leads to significant technical challenges with respect to solid-liquid separation and subsequent recovery of the precipitate. Despite the theoretically high metal removal, related to the low solubility of metal sulphides, practical efficiency is often significantly lower. Previous studies have shown that metal precipitation reactions require controlled physico-chemical conditions and the control of high levels of supersaturation to achieve optimum efficiency. The objective of this study was to extend this approach to metal suphide systems.Initial data indicated that conventional techniques to manage supersaturation were not effective and subsequent work focused on characterising the effect of reaction conditions on particle properties and investigating downstream processing options. The intention of this research was to bridge the gap between highly fundamental studies and practical application of sulphide precipitation technologies.en_ZA
dc.identifier.apacitationMokone, T. P. (2010). <i>Metal sulphide precipitation : effect of operational parameters on particle characteristics and process efficiency</i>. (Thesis). University of Cape Town ,Faculty of Engineering & the Built Environment ,Department of Chemical Engineering. Retrieved from http://hdl.handle.net/11427/13429en_ZA
dc.identifier.chicagocitationMokone, Thebe Phillip. <i>"Metal sulphide precipitation : effect of operational parameters on particle characteristics and process efficiency."</i> Thesis., University of Cape Town ,Faculty of Engineering & the Built Environment ,Department of Chemical Engineering, 2010. http://hdl.handle.net/11427/13429en_ZA
dc.identifier.citationMokone, T. 2010. Metal sulphide precipitation : effect of operational parameters on particle characteristics and process efficiency. University of Cape Town.en_ZA
dc.identifier.ris TY - Thesis / Dissertation AU - Mokone, Thebe Phillip AB - Acid mine drainage (AMD) is one of the major, long-term environmental challenges facing the minerals processing industry. Uncontrolled discharges have polluted thousands of kilometres of rivers, as well as surface and groundwater bodies with acidic effluents high in dissolved metals and sulphate. Conventional treatment technologies rely on oxidation, neutralisation and precipitation. While these may be effective they are expensive and not sustainable in the long term. Several biological treatment technologies, based on the activity of sulphate reducing bacteria (SRB), have been successfully developed and applied at both laboratory and industrial scale. The SRB uses sulphate as the terminal electron acceptor and with a suitable electron donor produce bicarbonate alkalinity and sulphide. These can be used to neutralise acidic effluents and effect precipitation of dissolved metal ions as metal sulphides. However, a number of challenges exist around the precipitation step, particularly where the recovery of valuable metals is desired. Metal sulphide precipitation reactions are inherently driven by extremely high levels of supersaturation. As a result, metal sulphide precipitation reactions are difficult to control and a large number of small particles are formed during the process. This leads to significant technical challenges with respect to solid-liquid separation and subsequent recovery of the precipitate. Despite the theoretically high metal removal, related to the low solubility of metal sulphides, practical efficiency is often significantly lower. Previous studies have shown that metal precipitation reactions require controlled physico-chemical conditions and the control of high levels of supersaturation to achieve optimum efficiency. The objective of this study was to extend this approach to metal suphide systems.Initial data indicated that conventional techniques to manage supersaturation were not effective and subsequent work focused on characterising the effect of reaction conditions on particle properties and investigating downstream processing options. The intention of this research was to bridge the gap between highly fundamental studies and practical application of sulphide precipitation technologies. DA - 2010 DB - OpenUCT DP - University of Cape Town LK - https://open.uct.ac.za PB - University of Cape Town PY - 2010 T1 - Metal sulphide precipitation : effect of operational parameters on particle characteristics and process efficiency TI - Metal sulphide precipitation : effect of operational parameters on particle characteristics and process efficiency UR - http://hdl.handle.net/11427/13429 ER - en_ZA
dc.identifier.urihttp://hdl.handle.net/11427/13429
dc.identifier.vancouvercitationMokone TP. Metal sulphide precipitation : effect of operational parameters on particle characteristics and process efficiency. [Thesis]. University of Cape Town ,Faculty of Engineering & the Built Environment ,Department of Chemical Engineering, 2010 [cited yyyy month dd]. Available from: http://hdl.handle.net/11427/13429en_ZA
dc.language.isoengen_ZA
dc.publisher.departmentDepartment of Chemical Engineeringen_ZA
dc.publisher.facultyFaculty of Engineering and the Built Environment
dc.publisher.institutionUniversity of Cape Town
dc.subject.otherChemical Engineeringen_ZA
dc.titleMetal sulphide precipitation : effect of operational parameters on particle characteristics and process efficiencyen_ZA
dc.typeDoctoral Thesis
dc.type.qualificationlevelDoctoral
dc.type.qualificationnamePhDen_ZA
uct.type.filetypeText
uct.type.filetypeImage
uct.type.publicationResearchen_ZA
uct.type.resourceThesisen_ZA
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