Characterization, settling, and rheology of concentrated fine particulate mineral slurries

Turian, Raffi M.; Ma, Tzu-Wang; Hsu, Feng-Lung; Sung, Deuk Jae

doi:10.1016/s0032-5910(97)03274-9

Cited by 80 publications

(45 citation statements)

References 21 publications

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“…Also, sedimentation is hindered markedly with increasing particulate concentration which enhances fluid drag [62][63][64][65][66]. Additionally, titanium dioxide slurry is known to have strong inter-particle interactions, which could increase hindered settling effects (from changes expected for discrete spheres) [51] and the presence of a wide size range is expected to enhance these interactions [67].…”

Section: Characterising Settling Suspensions; Ex Situ Technique Resultsmentioning

confidence: 99%

“…Its high refractive index renders an opaque suspension, unsuitable for characterisation via optical techniques. Furthermore its fine and cohesive particles readily aggregate, resulting in broad size distributions [1,50,51] which is more representative of commonly encountered suspensions. Furthermore at typically 1-2 µm, this acoustically attenuating size is at minimum an order of magnitude smaller relative to traditionally characterised particulate dispersions via acoustic backscatter analysis.…”

Section: Introductionmentioning

confidence: 99%

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In situ characterisation of a concentrated colloidal titanium dioxide settling suspension and associated bed development: Application of an acoustic backscatter system

et al. 2015

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ReuseUnless indicated otherwise, fulltext items are protected by copyright with all rights reserved. The copyright exception in section 29 of the Copyright, Designs and Patents Act 1988 allows the making of a single copy solely for the purpose of non-commercial research or private study within the limits of fair dealing. The publisher or other rights-holder may allow further reproduction and re-use of this version -refer to the White Rose Research Online record for this item. Where records identify the publisher as the copyright holder, users can verify any specific terms of use on the publisher's website. TakedownIf you consider content in White Rose Research Online to be in breach of UK law, please notify us by emailing eprints@whiterose.ac.uk including the URL of the record and the reason for the withdrawal request. eait.dean@uq.edu.au (S.Biggs). T.N.Hunter@leeds.ac.uk (T.N. Hunter).1 Present address: University of Queensland, Brisbane, Qld 4072, Australia 2 AbstractThe ability to accurately characterise the settling of particulate suspensions is imperative in numerous industries for improved processing, optimisation and control. Characterisation is typically a non-trivial process, and in situ measurements that remove the restriction of requiring particular sample sizes are preferred. Here for the first time, we explore the use of an acoustic backscatter system (ABS) to characterise key settling dynamics within a common colloidal mineral suspension, where backscatter attenuation is heightened due to the associated low scattering cross sections of the particles. Settling titanium dioxide dispersions with concentrations ranging 0.05 -3.00 vol% were successfully profiled using ABS transducers of 1, 2 and 4 MHz frequencies. This approach enabled the simultaneous visualisation of both the settling interface and sediment bed formation, generating sedimentation curves and eluding settling velocities. Furthermore, backscatter attenuation was empirically correlated with the attenuation-concentration relationship established for homogenous dispersions, to obtain concentration profiles of the settling suspensions. The data depicted concentration changes as a function of time in a hindered settling suspension, and allowed observation of the segregation of a size polydisperse suspension. Data were compared with sedimentation data obtained via two common ex situ bench-scale techniques. Critically, the acoustic backscatter method was validated as a powerful in situ characterisation tool for opaque concentrated heterogeneous dispersions, with the ability to provide concentration density information in conjunction with settling kinetics that is not easily attainable via other methods.

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Section: Characterising Settling Suspensions; Ex Situ Technique Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

In situ characterisation of a concentrated colloidal titanium dioxide settling suspension and associated bed development: Application of an acoustic backscatter system

et al. 2015

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“…There is a very large amount of critical deposition velocity data available in the literature, perhaps running into thousands (Oroskar and Turian, 1980;Soepyan et al, 2014;Turian et al, 1997). However, very few could be found that satisfied the four criteria given above.…”

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confidence: 99%

Constraints on the functional form of the critical deposition velocity in solid–liquid pipe flow at low solid volume fractions

Rice

Fairweather

Peakall

et al. 2015

Chemical Engineering Science

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Of the various transition velocities that delineate flow regimes in multiphase pneumatic and hydraulic conveying, the critical deposition velocity is important because it separates depositing and non-depositing flows. However, no distinction has been made between the dependence of the critical deposition velocity on physical parameters and flow conditions at low solid volume fractions and in the limit of zero volume fraction, which are distinct mathematically. Here, the two cases are analysed separately, and a general functional form in terms of the particle Reynolds number and Archimedes number is proposed that is valid up to volume fractions of several per cent. An ultrasonic method for determining the critical value of the particle Reynolds number is presented, and results for four particle types at several nominal volume fractions (0.5, 1 and 3 % by volume) are combined with a number of data from the literature. The resulting expressions are found to compare well with several similar correlations for the critical deposition velocity and other transition velocities, and, unlike a recent best-fit approach for the pick-up velocity, incorporate an explicit dependence on volume fraction, to which the critical deposition velocity is most sensitive at very low volume fractions. Lastly, it is found that the functional forms for the critical deposition velocity in the literature are unable to reproduce the available data at higher volume fractions, and a number of suggestions are made for resolving this issue.

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“…11 Slurries with a high concentration are typically characterized by measuring their rheological properties or sedimentation behaviors. [12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28] Rheological measurements are usually performed by estimating the level of particle dispersion or flocculation from viscosity curves. Slurries that contain agglomerations or flocculations of particles exhibit pseudoplastic or viscoplastic behavior, while dispersed slurries display Newtonian behavior.…”

Section: Introductionmentioning

confidence: 99%

Particle sedimentation monitoring in high-concentration slurries

2016

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In this study, the sedimentation states of particles in high-concentration slurries were elucidated by monitoring their internal states. We prepared transparent high-concentration silica slurries by adjusting the refractive index of the aqueous glycerol liquid in which the particles were dispersed to match that of the silica particles. In addition, a fluorescent dye was dissolved in the liquid. Then, we directly observed the individual and flocculated particles in the slurries during sedimentation by confocal laser scanning fluorescent microscopy. The particles were found to sediment very slowly while exhibiting fluctuating motion. The particle sedimentation rate in the high-concentration slurry with the aqueous glycerol solution (η=0.068Pa·s) and a particle volume fraction on the order of 0.3 was determined to be 1.58 ± 0.66 μm·min−1 on the basis of the obtained image sequences for 24.9 h. In-situ observation provides a large amount of information about the sedimentation behavior of particles in condensed matter.

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Characterization, settling, and rheology of concentrated fine particulate mineral slurries

Cited by 80 publications

References 21 publications

In situ characterisation of a concentrated colloidal titanium dioxide settling suspension and associated bed development: Application of an acoustic backscatter system

In situ characterisation of a concentrated colloidal titanium dioxide settling suspension and associated bed development: Application of an acoustic backscatter system

Constraints on the functional form of the critical deposition velocity in solid–liquid pipe flow at low solid volume fractions

Particle sedimentation monitoring in high-concentration slurries

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