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dc.contributor.authorNimah, Ulfa
dc.date.accessioned2019-09-16
dc.date.available2019-09-16
dc.date.issued2019-03-30
dc.identifier.urihttp://hdl.handle.net/2123/21124
dc.description.abstractThis thesis investigated the impact of secondary reactions; adsorption and precipitation, on nickel and cobalt recovery from bioleaching of nickel laterite ores. Although bioleaching is considered an ecologically and energy friendly technique to process laterite ores, low recoveries of target metals have inhibited its commercialisation. The secondary reactions occurrence in bioleaching of limonite, fresh and weathered saprolite ores was verified by performing chemical leaching tests using sulphuric and citric acid that would be generated by chemolithotrophs and heterotrophs respectively. The following leaching parameters were kept constant; pulp density at 10 (g/ml)%, particle size of the ore at 64 – 180 µm and stirring speed at 500 rpm. Metal loss was observed typically after 5 – 10 days and it increased as the acid to ore (A/O) ratio was reduced. At the lowest A/O ratio (0.1:1 (g/g)), up to 74% of nickel and 89% of cobalt were lost from target metals leached from saprolites while only 9% of nickel and negligible cobalt were lost from limonite. The mineralogical transformation of the residues resulting from the leaching process contributed to the alteration of the mineral isoelectric point (IEP) and consequently adsorption behaviour. The lower IEP in the saprolite residue (2.5 – 3.5) were attributed to the residual serpentine mineral (3.3) and quartz (2.2). While goethite (6.1 – 6.7) contributed to the higher IEP of the limonite residue (6.9). Systematic tests verified that adsorption can be overcome by maintaining the solution pH below the IEP of residues and adding complexing agent, 15 g/L of citric acid. A simulation of iron precipitation revealed little effect on metals recovery suggesting adsorption was as the primary secondary reaction affecting nickel laterite bioleaching. It is concluded that secondary reactions can have a huge impact on the metal recoveries and controlling its effect is critical in driving the commercialisation of the laterite bioleachingen_AU
dc.publisherUniversity of Sydneyen_AU
dc.publisherFaculty of Engineeringen_AU
dc.publisherSchool of Chemical and Biomolecular Engineeringen_AU
dc.rightsThe author retains copyright of this thesis. It may only be used for the purposes of research and study. It must not be used for any other purposes and may not be transmitted or shared with others without prior permission.en_AU
dc.subjectnickel lateriteen_AU
dc.subjectbioleachingen_AU
dc.subjectsecondary reactionsen_AU
dc.subjectadsorptionen_AU
dc.subjectisoelectric pointen_AU
dc.titleInvestigation of Secondary Reactions in Bioleaching of Nickel Laterite Oresen_AU
dc.typeMasters Thesisen_AU
dc.type.pubtypeMaster of Philosophy M.Philen_AU
dc.description.disclaimerAccess is restricted to staff and students of the University of Sydney . UniKey credentials are required. Non university access may be obtained by visiting the University of Sydney Library.en_AU


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