Correspondence of bubble size and frother partitioning in flotation

Abstract

The size of bubbles created in the flotation process is of great importance to the efficiency of the mineral separation achieved. Meanwhile, it is believed that frother transport between phases is perhaps the most important reason for the interactive nature of the phenomena occurring in the bulk and froth phases in flotation, as frother adsorbed in the surface of rising bubbles is removed from the bulk phase and then released into the froth as a fraction of the bubbles burst. This causes the increased concentration in the froth compared to the bulk concentration, named as frother partitioning. Partitioning reflects the adsorption of frother on bubbles and how to influence bubble size is not known. There currently exists no such a topic aiming to link these two key parameters. To fill this vacancy, the correspondence between bubble size and frother partitioning was examined. Bubble size was measured by sampling-for-imaging (SFI) technique. Using total organic carbon (TOC) analysis to measure the frother partitioning between froth and bulk phases was determined. Measurements have shown, with no exceptions including four different frothers, higher frother concentration is in the bulk than in the froth. The results also show strong partitioning giving an increase in bubble size which implies there is a compelling relationship between these two, represented by C_Froth/C_Bulk and D₃₂. The C_Froth/C_Bulk and D₃₂ curves show similar exponential decay relationships as a function of added frother in the system, strongly suggesting that the frother concentration gradient between the bulk solution and the bubble interface is the driving force contributing to bubble size reduction.

Keywords

flotation / frother / bubble size / frother partitioning / total organic carbon (TOC) analysis / concentration gradient

References

[1] ZieminskiS, CaronM, BlackmoreR. Behavior of air bubbles in dilute aqueous solutions [J]. Industrial & Engineering Chemistry Fundamentals, 1967, 6(2): 233-242

[2] KlimpelR, IsherwoodS. Some industrial implications of changing frother chemical structure [J]. International Journal of Mineral Processing, 1991, 33: 369-381

[3] LASKOWSKI J S. Frothers and flotation in frothing in flotation II [M]. Edited by LASKOWSKI J S, WOODBURN E T. New York: CRC Press Inc., 1998: 1–49.

[4] DobbyG S, FinchJ A. Particle collection in columns — gas rate and bubble size effects [J]. Canadian Metallurgy Quarterly, 1986, 25(1): 9-13

[5] GorainB K, FranzidisJ P, ManlapigE V. Studies on impeller type, impeller speed and air flow rate in an industrial scale flotation cell. part 1: Effect of bubble size distribution [J]. Minerals Engineering, 1995, 8(6): 615-635

[6] AhmedN, JamesonG J. The effect of bubble size on the rate of flotation of fine particles [J]. International Journal of Mineral Processing, 1985, 14(3): 195-215

[7] YoonR H, LuttrellG H. The effect of bubble size on fine coal flotation [J]. Coal Preparation, 1986, 2: 179

[8] HARRIS C C. Flotation machines [M]. Edited by FUERSTENAU M C. New York: SME of AIME, 1976: 753–815.

[9] HARRIS P J. Principles of frothers [M]. Edited by KING R P, Chapter 13, Johannesburg: South Africa: Institute of Mining and Metallurgy (IMM) Monograph Series. 1982: 237–263.

[10] FinchJ A, GelinaS S, MoyoP. Frother-related research at McGill University [J]. Minerals Engineering, 2006, 19(6/7/8): 726-733

[11] XuM, FinchJ A, Uribe-SalasA. Maximum gas and bubble surface rates in flotation columns [J]. International Journal of Mineral Processing, 1991, 32(3/4): 233-250

[12] MoyoP, GomezC O, FinchJ A. Characterizing frothers using water carrying rate [J]. Canadian Metallurgical Quarterly, 2007, 46(3): 215-220

[13] ZhangW, NessetJ E, FinchJ A. Water recovery and bubble surface area flux in flotation [J]. Canadian Metallurgical Quarterly, 2010, 49(4): 353-362

[14] ZangooiA, GomezC O, FinchJ AGomezC O, NessetJ E, RaoS R. Frother analysis in industrial flotation cells [C]. Proceeding of 48th Annual Conference of Metallurgists (CIM), Advances in Mineral Processing Science and Technology Symposium, 2009, Sudbury, CUM: 147-154

[15] ZhangW, ZhuS, FinchJ A. Frother partitioning in dual-frother systems: development of analytical technique [J]. International Journal of Mineral Processing, 2013, 119: 75-82

[16] GelinasS, FinchJ A. Frother analysis: Some plant experiences [J]. Mineral Engineering, 2007, 20(14): 1303-1308

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

[18] ZhangW, KolahdoozanM, NessetJ E, FinchJ A. Use of frother with sampling-for-imaging bubble sizing technique [J]. Minerals Engineering, 2009, 22(5): 513-515

[19] CappuccittiF, NessetJ EGomezC O, NessetJ E, RaoS R. Frother and collector effects on flotation cell hydrodynamics and their implication on circuit performance [C]. Proceeding of 48th Annual Conference of Metallurgists (CIM), Advances in Mineral Processing Science and Technology Symposium, 2009, Sudbury, CIM: 169-180

[20] GrauR A, LaskowskiJ S. Role of frothers in bubble generation and coalescence in a mechanical flotation cell [J]. Canadian Journal of Chemical Engineering, 2006, 84: 170-182

[21] AzgomiF, GomezC O, FinchJ A. Frother persistence: A measure using gas holdup [J]. Minerals Engineering, 2009, 22: 874-878

[22] ChoY S, LaskowskiJ S. Effect of flotation frothers on bubble size and foam stability [J]. International Journal of Mineral Processing, 2002, 64(2/3): 69-80

[23] NessetJ EModeling the Sauther mean bubble diameter in mechanical, flotation machines [D], 2011, Montreal, Canada, McGill University: 108-110

[24] ZhangW, NessetJ E, RaoS R, FinchJ A. Characterizing frothers through critical coalescence concentration (CCC95)-hydrophilic-lipophilic balance (HLB) [J]. Minerals, 2012, 2(3): 208-227

[25] ZhangW, ZhouX, FinchJ A. Determining independent control of dual-frother systems-gas holdup, bubble size and water overflow rate [J]. Minerals Engineering, 2012, 39: 106-116

[26] AlvesS S, MaiaC I, VasconcelosJ M T, SerralheiroA J. Bubble size in aerated stirred tanks [J]. Chemical Engineering Journal, 2002, 89: 109-117

[27] 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