This thesis has focused on the measurement of gas holdup in flotation systems, a variable not measured reliably to date. / A sensor was designed using so-called flow conductivity cells. Their properties were studied and modelled, and their application in the design, construction, and operation of a gas holdup probe for use in flotation systems described. / A flow cell is defined as one that allows a fluid or dispersion to flow through freely while the electrical conductivity is measured. One of the most important features of a flow cell is the so-called cell constant. Once the cell constant is determined, the cell can be used to measure liquid and dispersion conductivity. The cell constant depends mainly on cell dimensions, and is largely independent of the characteristics of the fluid. / The addition of non conductive bodies to the fluid was studied. It was concluded that the cell constant is not affected by the presence of such bodies. These systems are described by Maxwell's model, which relates the fraction of non conductive phase (holdup) in the system to the conductivity of the continuous phase and the conductivity of the dispersion. / It was demonstrated that the electromagnetic field associated with the flow cells can be solved using the MagNet 5.1 software. Predicted results for cell constant were in good agreement with the experimental. The model holds the potential for design of flow cells for particular applications in mineral processing. / The gas holdup probe developed in this work applies the principle of separation of phases to fulfill the requirements of Maxwell's model. The probe consists of two flow cells. One, the open flow cell, measures the conductivity of the dispersion while the other, the syphon cell, measures the continuum conductivity. / The test work, in both laboratory and industrial flotation columns, demonstrated that the probe gave accurate estimates of gas holdup. The probe satisfied the requirements of an industrial sensor, as it performs in-situ, on-line, in real-time, with no external measurements and no assumptions regarding properties of any phase. / The gas holdup probe was used to explore operating flotation columns. It appears to hold great promise for diagnosis, readily detecting, for example, differences in gas holdup between sections of baffled columns. / This success may make the probe a candidate sensor for process control, although this will require a significant in-plant effort to realize. As a first step, the probe offers an opportunity to study the relationship between gas holdup and metallurgy, at least in flotation columns.
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:QMM.34904 |
| Date | January 1996 |
| Creators | Tavera-Miranda, Francisco Javier. |
| Contributors | Finch, James A. (advisor) |
| Publisher | McGill University |
| Source Sets | Library and Archives Canada ETDs Repository / Centre d'archives des thèses électroniques de Bibliothèque et Archives Canada |
| Language | English |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Format | application/pdf |
| Coverage | Doctor of Philosophy (Department of Mining and Metallurgical Engineering.) |
| Rights | All items in eScholarship@McGill are protected by copyright with all rights reserved unless otherwise indicated. |
| Relation | alephsysno: 001564668, proquestno: NQ30400, Theses scanned by UMI/ProQuest. |
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