Investigation of particle-bubble interactions with a new experimental setup

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dc.contributor Aalto-yliopisto fi
dc.contributor Aalto University en
dc.contributor.author Schreithofer, Nóra
dc.date.accessioned 2012-02-10T09:03:19Z
dc.date.available 2012-02-10T09:03:19Z
dc.date.issued 2003-11-28
dc.identifier.isbn 951-22-6750-0
dc.identifier.uri https://aaltodoc.aalto.fi/handle/123456789/2127
dc.description.abstract Flotation is one of the most widely used processes in mineral beneficiation industry. Research on flotation circuit modelling and optimisation has for long time been of major importance. Flotation is mainly driven by surface chemical properties of the particles attaching to air bubbles. Earlier flotation models are based solely on dynamic consideration, but in the recent years serious research effort has been focused on finding surface chemical parameters, which may improve the existing flotation models. Parameters were mainly obtained from measurements performed with surface force apparatus, thin film balance techniques and atomic force microscopy. This thesis work aimed to design and develop a new experimental apparatus, suitable for in-depth study of particle-bubble interactions. The experimental results of this work provide additional data for the improvement of existing, and development of new flotation models. The new experimental setup named Colloidal Interaction Force Measurement Apparatus (CIFMA) is based on AFM force measurement principle. The apparatus eliminates the limitations caused by the small measurement range of commercial instruments and provides several new features that facilitate the in-depth investigation of particle-bubble interactions. In connection with the instrument design, the errors and problems associated with the technique are reviewed. The experiments conducted with CIFMA were focused on ultrapure, electrolyte containing and gas saturated aqueous systems. In addition the effects of approach velocity, applied load and contact time on the particle-bubble adhesion were studied. The results among others revealed, that the particle-bubble interaction process is time dependent, highly dynamic phenomena. The jump-in force and the adhesion decrease with time. Increased load and contact time enhance the adhesion of the particle to the air bubble even if no three-phase contact is formed. The nanometer-sized roughness of the particle surfaces has a significant effect on the particle-bubble adhesion. In ultrapure system a very long-range jump of the bubble towards the particle occurred, that was detected by optical means. With increasing electrolyte concentration this effect disappeared. These results emphasize the importance of reassessment of existing flotation models and development of new ones by taking into consideration the observed effects. en
dc.format.extent 108
dc.format.mimetype application/pdf
dc.language.iso en en
dc.publisher Helsinki University of Technology en
dc.publisher Teknillinen korkeakoulu fi
dc.relation.haspart Additional errata file available. en
dc.subject.other Materials science en
dc.subject.other Chemistry en
dc.title Investigation of particle-bubble interactions with a new experimental setup en
dc.type G4 Monografiaväitöskirja fi
dc.description.version reviewed en
dc.contributor.department Department of Materials Science and Rock Engineering en
dc.contributor.department Materiaali- ja kalliotekniikan osasto fi
dc.subject.keyword particle-bubble interactions en
dc.subject.keyword CIFMA en
dc.subject.keyword adhesion en
dc.subject.keyword applied load en
dc.subject.keyword contact time en
dc.subject.keyword time dependent effect en
dc.identifier.urn urn:nbn:fi:tkk-000957
dc.type.dcmitype text en
dc.type.ontasot Väitöskirja (monografia) fi
dc.type.ontasot Doctoral dissertation (monograph) en
dc.contributor.lab Laboratory of Mechanical Process Engineering and Recycling en
dc.contributor.lab Mekaanisen prosessi- ja kierrätystekniikan laboratorio fi


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