{"id":{"repo_id":"cape-town","oai_identifier":"oai:open.uct.ac.za:11427/17952"},"canonical_url":"https://search.dev.ndltd.org/etd/cape-town/oai:open.uct.ac.za:11427/17952","repository":{"repo_id":"cape-town","name":"University of Cape Town","base_url":"https://open.uct.ac.za/oai/request"},"display":{"title":"The ferric leaching of pyrite","abstract":"The bioleaching of pyrite has been found to occur via an indirect mechanism. Ferric iron leaches the pyrite, and is reduced to ferrous iron. Bacteria such as Thiobacillus ferrooxidans oxidise the ferrous iron to ferric iron, thus maintaining a high redox potential. In this thesis, the effect of the redox potential on the ferric leach rate was investigated by examining previously published data and by developing an experimental technique where dynamic redox potential measurements were used to study the kinetics of the sub-process. The ferric leach rate of pyrite was found to be of the order of 5 x 10⁻⁷ moles pyrite per mole pyrite per second, which is of the same order of magnitude as rates reported for the bioleaching of pyrite over similar ranges of redox potential. The rate decreased as the redox potential decreased, in what appeared to be a Butler-Volmer-like manner. This, along with the observation that there was no significant effect of the total iron concentration, suggested the likelihood of an electrochemical mechanism being operative, with charge transfer at the pyrite surface being rate limiting.","abstract_html":"The bioleaching of pyrite has been found to occur via an indirect mechanism. Ferric iron leaches the pyrite, and is reduced to ferrous iron. Bacteria such as Thiobacillus ferrooxidans oxidise the ferrous iron to ferric iron, thus maintaining a high redox potential. In this thesis, the effect of the redox potential on the ferric leach rate was investigated by examining previously published data and by developing an experimental technique where dynamic redox potential measurements were used to study the kinetics of the sub-process. The ferric leach rate of pyrite was found to be of the order of 5 x 10⁻⁷ moles pyrite per mole pyrite per second, which is of the same order of magnitude as rates reported for the bioleaching of pyrite over similar ranges of redox potential. The rate decreased as the redox potential decreased, in what appeared to be a Butler-Volmer-like manner. This, along with the observation that there was no significant effect of the total iron concentration, suggested the likelihood of an electrochemical mechanism being operative, with charge transfer at the pyrite surface being rate limiting.","abstract_has_math":false,"creators":["May, Noelene"],"institution":"Department of Chemical Engineering","degree_name":null,"degree_level":null,"degree_discipline":null,"degree_department":null,"school":null,"contributors":[],"advisors":["Hansford, Geoffrey Spearing"],"committee_chairs":[],"committee_members":[],"year":1997,"date_issued":"1997","date_published":"1997","updated_at":"2026-07-22T22:23:07Z","subjects":[],"languages":["eng"],"rights":[],"rights_urls":[],"identifier_entries":[]},"links":{"outbound_url":"http://hdl.handle.net/11427/17952","outbound_label":"Handle","outbound_source":"dc:identifier.uri"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor.advisor","label":"Advisor","values":["Hansford, Geoffrey Spearing"]},{"key":"dc:creator","label":"Author","values":["May, Noelene"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date.accessioned","label":"Dc Date Accessioned","values":["2016-03-17T12:42:26Z"]},{"key":"dc:date.available","label":"Dc Date Available","values":["2016-03-17T12:42:26Z"]},{"key":"dc:date.issued","label":"Date","values":["1997"]},{"key":"dc:publisher.department","label":"Dc Publisher Department","values":["Department of Chemical Engineering"]},{"key":"dc:publisher.institution","label":"Dc Publisher Institution","values":["University of Cape Town"]},{"key":"dc:type","label":"Dc Type","values":["Master Thesis"]},{"key":"dc:type.qualificationlevel","label":"Dc Type Qualificationlevel","values":["Masters"]},{"key":"dc:type.qualificationname","label":"Dc Type Qualificationname","values":["MSc (Eng)"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:language.iso","label":"Language (ISO)","values":["eng"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier.uri","label":"Identifier URI","values":["http://hdl.handle.net/11427/17952"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description","label":"Description","values":["Bibliography: pages 82-90."]},{"key":"dc:description.abstract","label":"Abstract","values":["The bioleaching of pyrite has been found to occur via an indirect mechanism. Ferric iron leaches the pyrite, and is reduced to ferrous iron. Bacteria such as Thiobacillus ferrooxidans oxidise the ferrous iron to ferric iron, thus maintaining a high redox potential. In this thesis, the effect of the redox potential on the ferric leach rate was investigated by examining previously published data and by developing an experimental technique where dynamic redox potential measurements were used to study the kinetics of the sub-process. The ferric leach rate of pyrite was found to be of the order of 5 x 10⁻⁷ moles pyrite per mole pyrite per second, which is of the same order of magnitude as rates reported for the bioleaching of pyrite over similar ranges of redox potential. The rate decreased as the redox potential decreased, in what appeared to be a Butler-Volmer-like manner. This, along with the observation that there was no significant effect of the total iron concentration, suggested the likelihood of an electrochemical mechanism being operative, with charge transfer at the pyrite surface being rate limiting."]},{"key":"dc:title","label":"Title","values":["The ferric leaching of pyrite"]}]}],"canonical_facts":{"dc:contributor.advisor":["Hansford, Geoffrey Spearing"],"dc:creator":["May, Noelene"],"dc:date.accessioned":["2016-03-17T12:42:26Z"],"dc:date.available":["2016-03-17T12:42:26Z"],"dc:date.issued":["1997"],"dc:description":["Bibliography: pages 82-90."],"dc:description.abstract":["The bioleaching of pyrite has been found to occur via an indirect mechanism. Ferric iron leaches the pyrite, and is reduced to ferrous iron. Bacteria such as Thiobacillus ferrooxidans oxidise the ferrous iron to ferric iron, thus maintaining a high redox potential. In this thesis, the effect of the redox potential on the ferric leach rate was investigated by examining previously published data and by developing an experimental technique where dynamic redox potential measurements were used to study the kinetics of the sub-process. The ferric leach rate of pyrite was found to be of the order of 5 x 10⁻⁷ moles pyrite per mole pyrite per second, which is of the same order of magnitude as rates reported for the bioleaching of pyrite over similar ranges of redox potential. The rate decreased as the redox potential decreased, in what appeared to be a Butler-Volmer-like manner. This, along with the observation that there was no significant effect of the total iron concentration, suggested the likelihood of an electrochemical mechanism being operative, with charge transfer at the pyrite surface being rate limiting."],"dc:identifier.uri":["http://hdl.handle.net/11427/17952"],"dc:language.iso":["eng"],"dc:publisher.department":["Department of Chemical Engineering"],"dc:publisher.institution":["University of Cape Town"],"dc:title":["The ferric leaching of pyrite"],"dc:type":["Master Thesis"],"dc:type.qualificationlevel":["Masters"],"dc:type.qualificationname":["MSc (Eng)"]},"updated_at":"2026-07-22T22:23:07Z"}