The theory of sediment volumes of compressible, particulate structures

Tiller, Frank M.; Khatib, Z.I.

doi:10.1016/0021-9797(84)90411-9

Cited by 99 publications

(49 citation statements)

References 14 publications

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“…Settling of flocculated suspensions is not well understood, given that flocculated suspensions do not fit the definition of dilute suspensions, where particles behave as independent flow units, and concentrated suspensions, where the translational and rotational degrees of freedom of the particles are severely restricted. Michaels and Bolger (1962), Buscall (1982), Tiller and Khatib (1984), and Buscall and White (1987) have proposed macroscopic theories for these systems that do not take into account the mechanisms that occur at the particle level during settling, but are vital to understand the macroscopic settling behavior of flocculated suspensions, as is demonstrated here. On the other hand, simulations resembling molecular dynamics have been widely used to elucidate the particle-particle mechanisms underlying settling of concentrated suspensions, but they have been either focused on the effect of Brownian forces (Dickinson and Parker, 1984; Ansell and Dickinson, 1987; Huang and Somasundaran, 1988; Dickinson, 1989) or on hydrodynamic interactions (Shih et al, 1987;Phillips et al, 1988;Brady et al, 1988; Koch and Shaqfeh, 1989); no emphasis has been put on interparticle interactions.…”

Section: Introductionmentioning

confidence: 93%

Settling behaviors of iron oxide suspensions

et al. 1993

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This article shows the settling behaviors of flocculated, magnetic and nonmagnetic iron oxide suspensions. It is unique, since in the literature on settling of model submicron flocculated particulate suspensions there is no direct visualization of the structures and how they change during settling. Channeling, cracking, and a novel collapse phenomenon were detected during settling. Causes were investigated using lapse videorecording for side and top views. The effect of air bubbles was shown to contribute to the accelerated settling of the suspension by creating channels that conduct oil to the settling front. Settling heights were recorded for long periods of time (up to a year) for iron oxidesuspensions of different concentrations. Decreasing tube diameters delayed settling, and magnetic interparticle forces produced smaller final settling heights. The effect of magnetic forces was interpreted in terms of a floc model. The model finds magnetic flocs 1.3 to 1.4 times denser than their nonmagnetic analogs. Finally, a mechanism i s put forth to interpret the settling behavior observed.

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Section: Introductionmentioning

confidence: 93%

Settling behaviors of iron oxide suspensions

et al. 1993

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“…The plots at a pressure of zero correspond to the final packing fraction of sediment obtained from the gravitational sedimentation test. 12 For slurries with an adsorbed amount of dispersant of 1.1 mgg Al 2 O 3 Fig. 7 a, the packing fraction was almost constant below 10 volಚ at all filtration pressures.…”

Section: Apparent Viscositymentioning

confidence: 84%

“…The slurry condensation behavior has been usually characterized by sedimentation or centrifugal sedimentation and there are many reports [12][13][14][15][16] associated with the sedimentation test. However, the experimental time is very long because the particle size is on the submicron order in the ceramics industry, therefore a new evaluation method is required to shorten experimental time.…”

Section: 10mentioning

confidence: 99%

Development of Slurry Characterization Method by Constant Pressure Filtration-Analysis of Cake Forming Behavior-

Kim

Mori

Tsubaki

2005

J. Ceram. Soc. Japan

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kƿȡ᧸ǦǮɁɱɲʀ△Ϣཪ⒈ǽϣ ââȹʀȷബ༔࿇ؔǽ╫ኝââ ʈ ઌშɿ᎓ ѝᅻɿᏊ ᚂʶȖ ۵‫ୖے‬গકগકрకકᮾ᳣ᲇᢼ֝൧కકଗფࢫ464-8603 ۵‫ୖے‬ల٣Ჷٚ˃ᨊThe particle-packing structure of Al 2 O 3 slurry was evaluated by using constant pressure filtration. The influences of initial solid concentration and dispersant amount on the cake forming behavior were discussed. It was shown that the packing fraction of formed cake is almost independent of filtration pressure under 10 volಚ of initial solid concentration. However at a relatively high solid concentration 20 and 35 volಚ, the packing fraction of cake increased with filtration pressure. The cake forming behavior was classified into four patterns by plotting the resistance of the formed cake as a function of particle volume in the formed cake; the plots were a a straight line, b a convex curve, c a concave curve, and d a combination of a concave curve and a flat line. The particle dispersion and flocculate degree were discussed on the basis of the results obtained by constant-pressure filtration.

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“…The present constitutive modeling practices (e.g. Tiller and Khatib, 1984;Bürger et al, 2000) can approximate the behavior of a microventing system in an average sense, but do not account for the mechanics of the process. More work needs to be done in this area.…”

Section: Resultsmentioning

confidence: 99%

The Channeling (Microventing) Phenomenon in Young Marine Sediments

Papanicolaou¹

2003

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LONG-TERM GOALSTo understand, evaluate, and quantify physical processes involved in the erosion, deposition, and transport of sediments. This involves short-term and long-term effects, and characterization of those effects based on sediment source and fluid mechanics. The outcome of this work will be a deeper understanding of the processes involved, and further development of predictive capabilities. OBJECTIVESThe objective of the present research is to explore the causes of microventing, a phenomenon generally occurring in cohesive sediments during their deposition and consolidation. Microvents are characterized by volcano-like formations, remnants of the expulsion of fluid and sediment along a vertical channel through the sediment layer. The size of these vent formations ranges from the order of millimeters to several centimeters, hence the term "microvent." Several causes proposed for microvents may be generally grouped as biological processes and mechanical processes. An example of a biological process is the production of subsurface gas due to organic decomposition; rising bubbles can produce microvents. The present study is concerned only with mechanical processes, which are hypothesized to be: A) Pressure fluctuations in pore fluid; B) Solids concentration perturbations near sediment-suspension interface; C) Gas expulsion by sediment compression. The overall scope of this investigation is to describe the microventing process in pure clay sediments and in young marine sediment deposits. Specific tasks of this project are: I) Identify whether microventing occurs in consolidation of kaolinite from a low initial concentration II) Identify the control parameter for microventing through different methods of detection III) Perform controlled tests to determine threshold of fluidization Incorporate this knowledge into a numerical code This information will ultimately be used in a quantitative model that predicts the rate of deposition and consolidation of sediment, but does not presently account for microvents (Papanicolaou and Diplas, 1999). Knowledge of microvent formation is also important in defining the erosional stability of young sediments, and such information will be useful to scientists and engineers in several disciplines, including those focusing on the prediction of fate and transport of contaminated sediments and those focusing on the refinement of existing remediation techniques in riverine and estuarine systems .

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The theory of sediment volumes of compressible, particulate structures

Cited by 99 publications

References 14 publications

Settling behaviors of iron oxide suspensions

Settling behaviors of iron oxide suspensions

Development of Slurry Characterization Method by Constant Pressure Filtration-Analysis of Cake Forming Behavior-

The Channeling (Microventing) Phenomenon in Young Marine Sediments

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