Method Of Determination Of Phase Composition
METHOD OF DETERMINATION OF PHASE COMPOSITION
OF THE AGGREGATES FLOATING INSIDE FLOTATION CELL
K. Malysa1, P. Warszynski1, S. Ng2
1Institute of Catalysis and Surface Chemistry Polish Academy of Sciences, ul.Niezapominajek 8, 30-239 Cracow, Poland
2Syncrude Research Center, Edmonton, Canada
In flotation the grains of useful component of an ore are always transported to froth layer in a form of the bubble-grain aggregates. Density of the mineral grains is usually higher than density of the fluid medium and without attachment to air bubbles they would sink instead of floating. A resultant apparent density of the aggregate floating to froth layer is lower than medium density, but higher than air density. Thus, amounts of solids attached to the air bubble can be calculated on a basis of differences in rise velocities of the aggregates and unloaded air bubbles of identical dimensions.
Method of determination of size, rising velocity and phase composition of the aggregates floating toward the froth layer is presented. Fluxes of the aggregates inside the flotation cell were monitored using the device called Luba Tube and recorded on videotapes. The experiments analyzed were carried out in a 0.51m diameter Primary Separation Vessel. Dimensions of the aggregates were measured on sequences of frames grabbed from the video recordings using the image analysis software. Rise velocities of the aggregates were determined from the displacements of the aggregate positions between the consecutive frames. A relationship describing rise velocity of unloaded air bubbles of identical dimensions as the aggregates was used as the "reference state" for calculation the mass of bitumen contained in the aggregates.
It was found that grade of the ore processed under identical conditions had a clear effect on the size of the aggregates and their phase composition. During processing of 11.1 % bitumen oil sand in temperature 50° C the average bitumen-air aggregate had an equivalent diameter of an order of 1 mm and contained ca. 9.0·10-4 g of bitumen. In the case of a low grade (7.2 % of bitumen) oil sand the average value of the aggregate equivalent diameter was much lower (within 0.33-0.69 mm) and the aggregates carried less bitumen, from 0.17-1.37·10-4 g depending on the operating conditions (caustic dosage).
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