Numerical simulation of flocculation and settling behavior of whole-tailings particles in deep-cone thickener

Abstract

Rapid dewatering and thickening of whole-tailings with ultrafine particles is one of the most important processes for the whole-tailings paste preparation. Deep-cone thickener, a kind of such process for the flocculation and settling of whole-tailings, is particularly necessary to study. However, there exist many problems in observing the flocculation and settling process of whole-tailings, as well as the particle size distribution (PSD) of whole-tailings floccules in deep-cone thickener. Population balance model (PBM) is applied to predict the PSD in deep-cone thickener, and LUO model and GHADIRI model are employed to study the aggregation and fragmentation mechanism of the whole-tailings particles, respectively. Through three-dimensional numerical simulation on the whole-tailings flocculation and settling in deep-cone thickener using computational fluid dynamics (CFD)-PBM, the distribution of density and turbulent kinetic energy in deep-cone thickener were obtained, at the same time the spatio-temporal changes of whole-tailings floccules particle size distribution are analyzed. Finally, the major flocculation position in deep-cone thickener is found and the flocculation settling rules of whole-tailings are achieved.

Keywords

whole-tailings particles / flocculation settling / numerical simulation / deep-cone thickener / population balance model

References

[1] GrabinskyM. W.. In situ monitoring for ground truthing paste backfill designs [C]. Proceedings of the 13th International Seminar on Paste and Thickened Tailings. Perth: Australian Centre for Geomechanics, 201085-98

[2] ZhangQ.-l., ZhouD.-h., WangX.-m., ZhaoJ.-w.. Experimental study on flocculating sedimentation of ultra-fine unclassified tailings [J]. J Guangxi Univ: Nat Sci Ed, 2013, 38(2): 452-455

[3] BäurgeraR., DamascenobJ. J. R., KarlsencK. H.. A mathematical model for batch and continuous thickening of flocculated suspensions in vessels with varying cross section [J]. Int J Miner Process, 2004, 73: 183-208

[4] UsherS. P., SpeharR., ScalesP. J.. Theoretical analysis of aggregate densification: Impact on thickener performance [J]. Chem Eng J, 2009, 151(1): 202-208

[5] UsherS. P., ScalesP. J.. Steady state thickener modelling from the compressive yield stress and hindered settling function [J]. Chem Eng J, 2005, 111(2): 253-261

[6] SpeharR., Kiviti-ManorA., FawellP., UsherS. P., RudmanM., ScalesP. J.. Aggregate densification in the thickening of flocculated suspensions in an un-networked bed [J]. Chem Eng Sci, 2015, 122: 585-595

[7] EswaraiahC., BiswalS. K., MishraB. K.. Settling characteristics of ultrafine iron ore slimes [J]. Int J Miner Metall Mater, 2012, 19(2): 95-99

[8] DuJ.-h., PushkarovaR. A., SmartR., SC.. A cryo-SEM study of aggregate and floc structure changes during clay settling and raking processes [J]. Int J Miner Process, 2009, 93(1): 66-72

[9] SelomuyaC., JiaX., WilliamsR. A.. Direct prediction of structure and permeability of flocculated structures and sediments using 3D tomographic imaging [J]. Chem Eng Res Des, 2005, 83(7): 844-852

[10] GarridoP., BurgosR., ConchaF., BurgerF.. Software for the design and simulation of gravity thickeners [J]. Miner Eng, 2003, 16(2): 85-92

[11] BurgosR., ConchaF.. Further development of software for the design and simulation of industrial thickeners [J]. Chem Eng J, 2005, 111(2): 135-144

[12] KahaneR., NguyenT., SchwarzM. P.. CFD modelling of thickeners at Worsley alumina Pty Ltd [J]. Appl Math Modeling, 2002, 26(2): 281-296

[13] WhiteR. B., SutaloI. D., NguyenT.. Fluid flow in thickener feedwell models [J]. Miner Eng, 2003, 16(2): 145-150

[14] OwenA. T., NguyenT. V., FawellP. D.. The effect of flocculant solution transport and addition conditions on feedwell performance in gravity thickeners [J]. Int J Miner Process, 2009, 93(2): 115-127

[15] TanguayM., FawellP., AdkinsS.. Modelling the impact of two different flocculants on the performance of a thickener feedwell [J]. Appl Math Modelling, 2014, 38: 4262-4276

[16] ZhuG.-h., ZhangY.-z., RenJ.-l., QiuT.-h., WangT.. Flow simulation and analysis in a vertical-flow sedimentation tank [C]. 2012 International Conference on Future Energy, Environment, and Materials. Energy Procedia, 2012, 16: 197-202

[17] KahaneR. B., SchwarzM. P., JohnstonR. M.. Residue thickener modelling at Worsley alumina [C]. International Conference on CFD in Mineral & Metal Processing and Power Generation. Melbourne: CSIRO, 1997109-118

[18] NguyenT., HeathA., WittP.. Population balance-CFD modelling of fluid flow, solids distribution and flocculation in thickener feedwells [C]. Fifth International Conference on CFD in the Process Industries. Melbourne: CSIRO, 20061-6

[19] NopensI., BiggsC. A., ClercqB., GovoreanuR., WilénB. M., LantP., VanrolleghemP. A.. Modelling the activated sludge flocculation process combining laser light diffraction particle sizing and population balance modelling (PBM) [J]. Water Sci Technol, 2002, 45(6): 41-49

[20] HeathA. R., PeterT. L. K.. Combined population balance and CFD modeling of particle aggregation by polymeric flocculants [C]. Third International Conference on CFD in the Minerals and Process Industries. Melbourne: CSIRO, 2003339-344

[21] WeiH.Application of computational fluid dynamics techniques to the modelling of precipitation processes [D], 1997

[22] GarsideJ., WeiH.. Pumped stirred and maybe precipitated: simulation of precipitation process using CFD [J]. Acta Polytech Scand, Chem Technol Metall Ser, 1997, 245: 9-15

[23] ChengJ.-c., YangC., MaoZ.-s.. CFD-PBE simulation of premixed continuous precipitation incorporating nucleation, growth and aggregation in a stirred tank with multi-class method [J]. Chem Eng Sci, 2012, 68(1): 469-480

[24] JaworskiZ., NienowA. W.. CFD modelling of continuous precipitation of barium sulphate in a stirred tank [J]. Chem Eng J, 2003, 91: 167-174

[25] WangZ., MaoZ.-s., YangC., ShenX.-q.. Computational fluid dynamics approach to the effect of mixing and draft tube on the precipitation of barium sulfate in a continuous stirred tank [J]. Chin J Chem Eng, 2006, 14(6): 713-722

[26] VicumL., MazzottiM.. Multi-scale modeling of a mixing-precipitation process in a semibatch stirred tank [J]. Chem Eng Sci, 2007, 62: 3513-3527

[27] ChengJ.-c., YangC., MaoZ.-s., ZhaoC.-j.. CFD modeling of nucleation, growth, aggregation, and breakage in continuous precipitation of barium sulfate in a stirred tank [J]. Ind Eng Chem Res, 2009, 48(15): 6992-7003

[28] YakhotV., OrszagS. A.. Renormalization group analysis of turbulence [J]. J Sci Comput, 1986, 1(1): 3-51

[29] RandolphA. D., LarsonM. A.Theory of particulate processes [J], 198841-63

[30] RamkrishnaD.Population balance: Theory and application to Particulate Systems in Engineering [J], 20007-45

[31] MarchisioD. L., VigilR. D., FoxR. O.. Quadrature method of moments for aggregation-breakage processes [J]. J Colloid Interface Sci, 2003, 258: 322-334

[32] McgrawR.. Description of aerosol dynamics by the quadrature method of moments [J]. Aerosol Sci Technol, 1997, 27(2): 255-265

[33] MarchisioD. L., VigilR. D., FoxR. O.. Implementation of the quadrature method of moments in CFD codes for aggregation-breakage problems [J]. Chem Eng Sci, 2003, 58: 3337-3351

[34] MarchisioD. L., PikturnaJ. T., FoxR. O., VigilR. D.. Quadrature method of moments for population-balance equations [J]. AICh E J, 2003, 49(5): 1266-1276

[35] MarchisioD. L., SoosM., SefcikJ., MorbidelliM.. Role of turbulent shear rate distribution in aggregation and breakage processes [J]. AICh E J, 2006, 52(1): 158-173

[36] WangL., MarchisioD. L., VigilR. D., FoxR. O.. CFD simulation of aggregation and breakage processes in laminar Taylor-Couette flow [J]. J Colloid Interface Sci, 2005, 282: 380-396

[37] LuoH.-a.Coalescence, breakup and liquid circulation in bubble column reactors [D], 1993TrondheimNorwegian Institute of Technology

[38] GhadiriM., ZhangZ.. Impact attrition of particulate solids. Part 1: A theoretical model of chipping [J]. Chem Eng Sci, 2002, 57: 3659-3669

[39] TaoD., ParekhB. K., ZhaoY.-m., ZhangP.. Pilot-scale demonstration of deep coneTM paste thickening process for phosphatic clay/sand disposal [J]. Sep Sci Technol, 2008, 45(10): 1418-1425

[40] WuA.-x., SunY.-z.Granular dynamic theory and its applications [J], 2008135-138

[41] LiH., WangH.-j., WuA.-x., JiaoH.-z., LiuX.-h.. Pressure rake analysis of deep cone thickeners based on tailings’ settlement and rheological characteristics [J]. J Univ Sci Technol Beijing, 2013, 35(12): 1553-1558