Hydrodynamics and gas dispersion in industrial flotation cells

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dc.contributor.advisorFranzidis, Jean-Paulen_ZA
dc.contributor.authorEgya-Menash, Danielen_ZA
dc.date.accessioned2016-10-19T13:37:58Z
dc.date.available2016-10-19T13:37:58Z
dc.date.issued1999en_ZA
dc.descriptionBibliography: pages [201]-212.en_ZA
dc.description.abstractSolids suspension and gas dispersion studies were performed on a total of 40 industrial flotation cells of various types, sizes and duties in a Platinum Group Metal (pgm) concentrator in the North West Province of South Africa. The wide variety of cells studied included a Bateman 3-m³ cell, Outokumpu 16-m³ conventional and 50-m³ TankCells, WEMCO 84, 120, 144 cells and WEMCO 144 with 164 mechanism and high-power motor. The gas phase properties of bubble size, superficial gas velocity, air holdup and bubble surface area flux were used in characterising these cells. The bubble size was measured at six different locations in the cells using the UCT Bubble Size Analyser. The superficial gas velocity and gas holdup were measured similarly with other special designed devices. The bubble surface area flux, a new parameter for characterising the hydrodynamics and gas dispersion in flotation cells, was calculated from the ratio of the superficial gas velocity to the Sauter mean bubble size. The results of these measurements were analysed in terms of key variables including air flowrate, impeller speed and location in the cell. The bubble size was found to increase with increasing air flowrate and decreasing impeller speed. Bubbles in the impeller zone were found to be smaller than bubbles in the quiescent zone due to significant bubble coalescence in this region. The bubble size was also found to be inversely related to the power consumption provided that this was expressed on an impeller-swept-volume basis. The superficial gas velocity was found to increase with increasing air flowrate and impeller speed and was significantly affected by location in the cell. Differences in superficial gas velocities were observed at constant air flowrates and at different impeller speeds. This unexpected finding was attributed to differences in flow patterns in the cells. Air holdup was found to be largely insensitive to changes in air flowrate and impeller speed in cells operating at their normal conditions. Differences in air holdup in the quiescent and turbulent zones were observed but these were more noticeable in smaller cells. The bubble surface area flux in industrial flotation cells was found to be in the range of 50-60 m²/m²/s irrespective of the type, size and duty of cell. However, it was observed that the bubble surface area flux could be varied by manipulating certain key cell variables such as the impeller speed and the air flowrate. The bubble surface area flux was found to increase with increasing air flowrate until reaching an optimum at sufficiently high air flowrates.en_ZA
dc.identifier.apacitationEgya-Menash, D. (1999). <i>Hydrodynamics and gas dispersion in industrial flotation cells</i>. (Thesis). University of Cape Town ,Faculty of Engineering & the Built Environment ,Department of Chemical Engineering. Retrieved from http://hdl.handle.net/11427/22206en_ZA
dc.identifier.chicagocitationEgya-Menash, Daniel. <i>"Hydrodynamics and gas dispersion in industrial flotation cells."</i> Thesis., University of Cape Town ,Faculty of Engineering & the Built Environment ,Department of Chemical Engineering, 1999. http://hdl.handle.net/11427/22206en_ZA
dc.identifier.citationEgya-Menash, D. 1999. Hydrodynamics and gas dispersion in industrial flotation cells. University of Cape Town.en_ZA
dc.identifier.ris TY - Thesis / Dissertation AU - Egya-Menash, Daniel AB - Solids suspension and gas dispersion studies were performed on a total of 40 industrial flotation cells of various types, sizes and duties in a Platinum Group Metal (pgm) concentrator in the North West Province of South Africa. The wide variety of cells studied included a Bateman 3-m³ cell, Outokumpu 16-m³ conventional and 50-m³ TankCells, WEMCO 84, 120, 144 cells and WEMCO 144 with 164 mechanism and high-power motor. The gas phase properties of bubble size, superficial gas velocity, air holdup and bubble surface area flux were used in characterising these cells. The bubble size was measured at six different locations in the cells using the UCT Bubble Size Analyser. The superficial gas velocity and gas holdup were measured similarly with other special designed devices. The bubble surface area flux, a new parameter for characterising the hydrodynamics and gas dispersion in flotation cells, was calculated from the ratio of the superficial gas velocity to the Sauter mean bubble size. The results of these measurements were analysed in terms of key variables including air flowrate, impeller speed and location in the cell. The bubble size was found to increase with increasing air flowrate and decreasing impeller speed. Bubbles in the impeller zone were found to be smaller than bubbles in the quiescent zone due to significant bubble coalescence in this region. The bubble size was also found to be inversely related to the power consumption provided that this was expressed on an impeller-swept-volume basis. The superficial gas velocity was found to increase with increasing air flowrate and impeller speed and was significantly affected by location in the cell. Differences in superficial gas velocities were observed at constant air flowrates and at different impeller speeds. This unexpected finding was attributed to differences in flow patterns in the cells. Air holdup was found to be largely insensitive to changes in air flowrate and impeller speed in cells operating at their normal conditions. Differences in air holdup in the quiescent and turbulent zones were observed but these were more noticeable in smaller cells. The bubble surface area flux in industrial flotation cells was found to be in the range of 50-60 m²/m²/s irrespective of the type, size and duty of cell. However, it was observed that the bubble surface area flux could be varied by manipulating certain key cell variables such as the impeller speed and the air flowrate. The bubble surface area flux was found to increase with increasing air flowrate until reaching an optimum at sufficiently high air flowrates. DA - 1999 DB - OpenUCT DP - University of Cape Town LK - https://open.uct.ac.za PB - University of Cape Town PY - 1999 T1 - Hydrodynamics and gas dispersion in industrial flotation cells TI - Hydrodynamics and gas dispersion in industrial flotation cells UR - http://hdl.handle.net/11427/22206 ER - en_ZA
dc.identifier.urihttp://hdl.handle.net/11427/22206
dc.identifier.vancouvercitationEgya-Menash D. Hydrodynamics and gas dispersion in industrial flotation cells. [Thesis]. University of Cape Town ,Faculty of Engineering & the Built Environment ,Department of Chemical Engineering, 1999 [cited yyyy month dd]. Available from: http://hdl.handle.net/11427/22206en_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.titleHydrodynamics and gas dispersion in industrial flotation cellsen_ZA
dc.typeMaster Thesis
dc.type.qualificationlevelMasters
dc.type.qualificationnameMSc (Eng)en_ZA
uct.type.filetypeText
uct.type.filetypeImage
uct.type.publicationResearchen_ZA
uct.type.resourceThesisen_ZA
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