A novel approach to prevent bubble coalescence during measurement of bubble size in flotation

Abstract

Effect of frothers in preventing bubble coalescence during flotation of minerals has long been investigated. To evaluate the performance of a frother, an apparatus to measure the bubble size is a basic necessity. McGill Bubble Size Analyzer (MBSA) or bubble viewer that has been developed and completed by McGill University’s Mineral Processing Group during the last decade is a unique instrument to serve this purpose. Two parameters which are thought to influence the bubble size measurements by McGill bubble viewer include water quality and frother concentration in the chamber. Results show that there is no difference in Sauter mean (D₃₂) when tap or de-ionized water was used instead of process water. However, the frother concentration, in this research DowFroth 250 (DF250), inside the chamber exhibited a pronounced effect on bubble size. Frother concentration below a certain point can not prevent coalescence inside the chamber and therefore caution must be taken in plant applications. It was also noted that the frother concentration which has been so far practiced in plant measurements (CCC75-CCC95) is high enough to prevent coalescence with the bubble viewer.

Keywords

flotation / frother / bubble size / bubble coalescence

References

[1] HARRIS C C. Flotation machines [M]. Fuerstenau, M.C. (Ed.), A.M. Gaudin Memorial Volume, Vol. 2, SME of AIME, 1976, 753–815.

[2] METSO MINERALS CBT (Computer Based Training). Mill Operator Training Package: Flotation Module [R]. Formerly Brenda Process Technology CBT (Computer Based Training), 1996.

[3] ChoY S, LaskowskiJ S. Effect of flotation frothers on bubble size and foam stability [J]. International Journal of Mineral Processing, 2002, 64: 69-80

[4] NessetJ E, FinchJ A, GomezC O. Operating variables affecting the bubble size in forced-air mechanical flotation machines [C]. Proceedings of Ninth Mill Operators’ Conference. Fremantle, WA, 200719-21

[5] FinchJ A, NessetJ E, AcunaC. Role of frother on bubble production and behaviour in flotation [J]. Minerals Engineering, 2008, 21(12/13/14): 949-957

[6] Hernandez-AguilarJ R, GomezC O, FinchJ A. A technique for the direct measurement of bubble size distribution in industrial flotation cells [C]. Proceedings 2002-34th Annual Meeting of the Canadian Mineral Processors (CIM). Ottawa, ON, 2002389-402

[7] GrauR A, HeiskanenK. Visual technique for measuring bubble size in flotation systems [J]. Minerals Engineering, 2002, 15: 507-513

[8] BaileyM, Torrealba-VargasJ, GomezC O, FinchJ A. Coalescence of bubbles sampled for imaging [J]. Minerals Engineering, 2005, 18: 125-126

[9] MalysaK, KrasowskaM, KrzanM. Influence of surface active substances on bubble motion and collision with various interfaces [J]. Advances in Colloid and Interface Science, 2005, 114–115: 205-225

[10] McGill gas dispersion set-up and operation manual [R]. Montreal, QC: Department of Mining and Materials Engineering, McGill University, 2006.

[11] TseK L, MartinT, McfarlaneC M, NienowA W. Small bubble formation via a coalescence dependent break-up mechanism [J]. Chemical Engineering Science, 2003, 58: 1497-1519

[12] AcunaC, NessetJ E, FinchJ Adel VillarR, NessetJ E, GomezC O, StradlingA W. Impact of frother on bubble production and behaviour in the pulp zone [C]. Proceedings of the 6th International Copper-Cobre Conference, Volume II Mineral Processing, 2007, Toronto, ON, Canada, MetSoc CIM: 197-210

[13] PyechaJ, SimsS, LacoutureB, HopeG, StradlingA. Evaluation of a microcel sparger in the Red Dog column flotation cells [C]. Centenary of Flotation Symposium. Brisbane, 20051017-1025

[14] LizamaH M, CarrionJ, EstrellaD. Improvements in column flotation through the use of MicrocelTM spargers at Antamina [C]. Proceedings of 40th Annual Meeting of Canadian Mineral Processors (CIM). Ottawa, 2008363-376

[15] GomezC O, FinchJ A. Gas dispersion measurements in flotation cells [J]. International Journal of Mineral Processing, 2007, 84: 51-58