Frother-related research at McGill University |
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| Affiliation: | 1. Centre for Minerals Research, Department of Chemical Engineering, University of Cape Town, Cape Town, South Africa;2. State Key Laboratory of Mineral Processing, Beijing General Research Institute of Mining and Metallurgy, Beijing, China;1. Eriez Magnetics Pty Ltd, 21 Shirley Way, Epping, Victoria 3076, Australia;2. Eriez Manufacturing Company, 2200 Asbury Road, Erie, PA 16506, United States;1. Department of Mining Engineering, West Virginia University, 365 Mineral Resources Building, 1374 Evansdale Drive, Morgantown, WV, 26506, USA;2. Department of Mining Engineering, Arak University of Technology, Arak, Iran;3. Department of Mining Engineering, Tarbiat Modares University, Tehran, Iran;1. Key Laboratory of Coal Processing and Efficient Utilization (Ministry of Education), School of Chemical Engineering and Technology, China University of Mining and Technology, Xuzhou 221116, China;2. School of Mechanical and Power Engineering, East China University of Science and Technology, Shanghai 200237, China;3. Department of Chemical and Materials Engineering, University of Alberta, Edmonton, Alberta T6G 1H9, Canada;4. College of New Materials and New Energies, Shenzhen Technology University, Shenzhen 518118, China |
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| Abstract: | Over the past ten years the Mineral Processing group at McGill University has developed techniques to determine gas dispersion properties (gas superficial velocity, gas holdup, bubble size and bubble surface area flux) in flotation machines. This work is finding application in metallurgical diagnostics and cell characterization. The picture, however, will remain incomplete until the impact of chemistry on bubble production, and hence on gas dispersion, is understood. This has prompted investigations into frothers.There are two areas addressed in this communication: frother analysis and frother characterization.Coincident with the centenary, for 100 years there was no convenient frother analysis procedure. A colorimetric technique originally developed for alcohols had been applied to MIBC (Parkhomovski, V.L., Petrunyak, D.G., Paas, L., 1976. Determination of methylisobutylcarbinol in waste waters of concentration plants. Obogashchenie Rud 21 (2), 44–45). Using this as a starting point, the technique was successfully extended to a wide range of commercial frothers and shown to be robust against most common ‘contaminants’. The technique is readily used on-site and some observations from plant surveys are described.Characterization of frothers has taken two routes, determining water carrying rate and investigating properties of thin bubble films.Second only to transporting particles the recovery of water by bubbles has the most influence on metallurgy. The question posed was whether this ‘water carrying’ property could be related to frother type. In a specially designed column the volume rate of water to the overflow per unit cross-sectional area (‘carrying rate’, Jwo) and gas holdup (εg) at controlled froth depths were measured. The Jwo–εg relationship proved approximately linear and dependent on frother type, with four frother ‘families’ being identified.Bubble thin films have been studied for soaps and the techniques were adapted for frothers. From infrared analysis it became apparent that the frother molecule, while itself not seen, had an impact on organizing water molecules, apparently forming a film of bound water on the bubble surface. Exploiting the interference pattern generated in UV/Vis the film thickness (d) was determined; for MIBC d was less than 160 nm while for DF250 d was ～600 nm. Taking a representative frother from the four families identified above, the water carrying rate at a given gas holdup increased with film thickness.Possible implications of the findings on the role of frother in bubble production are explored. |
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