The distribution of fluidization flow of a variable speed 3-in (7.5 cm) Knelson centrifugal concentrator was first studied. Its performance was then investigated for different types of synthetic ores, and the effect of rotation speed, fluidizing water, gangue density and size distribution, and feed rate determined. To obtain some fundamental information relative to the recovery mechanisms of the Knelson Concentrator, the percolation or migration of dense particles in a gangue bed was investigated in the gravitational field, using a fluidization column. The equations for determining the instantaneous radial settling velocity of a spherical particle in the dilute zone of the inner bowl were derived for the Stokes' Law region. / Recovery of tungsten from magnetite and silica gangues and recovery of magnetite from silica gangue were studied. Results indicate that rotating speed of the Knelson Concentrator affected both the movement of mineral particles and fluidization of the separation zone, which in turn affected KC performance. For all types of feeds studied, the fluidizing water flow rate needed to achieve a maximum recovery increased with increasing rotating speed. The study of capture kinetics showed that tungsten recovery from silica decreased gradually and almost linearly as the feed rate increased from 0.5 to 5 kg/min; this decrease became smaller with increasing Gs. However, the recovery drop (or the corresponding capture rate constant) was small for coarse (>106 mum) tungsten and moderate for fine (<106 mum) tungsten, suggesting that for typical applications of gold recovery from the circulating load of a grinding circuit, feed rate should be maximized. Further, accelerations of 30 to 60 Gs were adequate for very good recovery of tungsten above 25 mum. The recovery of magnetite from a -425 mum silica gangue was limited to a d 50c of 40 mum. Rotation velocity had little impact on how fine magnetite could be recovered, especially above the velocity corresponding to 60 Gs. / At 1 Gs (i.e. in the gravitational field), an optimum fluidization flow was also observed for all systems studied. High density gangue, especially when coarse, had a detrimental effect on percolation and migration. Particles of high density percolated or migrated faster than those of lower density. When the gangue bed was well fluidized, the migration rate of coarse particles was higher than the percolation rate of fines. These observations are basically consistent with the effect of fluidization water, gangue size distribution and density on Knelson performance.
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:QMM.35468 |
| Date | January 1998 |
| Creators | Ling, Jinghong, 1948- |
| Contributors | Laplante, Andre R. (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: 001655594, proquestno: NQ50209, Theses scanned by UMI/ProQuest. |
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