Settling behaviors of iron oxide suspensions

Glasrud, G.G.; Navarrete, R.C.; Scriven, L. E.; Macosko, Chris

doi:10.1002/aic.690390404

Cited by 37 publications

(36 citation statements)

References 25 publications

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“…For the 2:l diluted sample, the solids settled 3.8 cm (62% of the 6.13 cm total height) in about 24 hours. This behavior is consistent with that commonly observed in the sedimentation of certain metal hydroxides (see, for example Glasrud et al 1993) and has been observed with both Hanford wastes and waste simulants (Rector and Bunker 1995). supernatant liquid or an equimolar sodium hydroxide and salt solution), differences in waste chemistry make applying these results to the current mobilization and retrieval scenario rather difficult.…”

Section: Settled Slurry Volume Fraction and Sedimentation Behaviorsupporting

confidence: 88%

Waste mixing and diluent selection for the planned retrieval of Hanford Tank 241-SY-102: A preliminary assessment

Onishi¹,

Hudson²

1996

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Portions of this document rrmy be iIlegible in electronic image products. Images are produced from the best available original docmnent. SummaryThis preliminary assessment documents a set of analyses that were performed to determine the potential for Hanford waste Tank 241-SY-102 waste properties to be adversely affected by mixing the current tank contents or by injecting additional diluent into the tank during sludge mobilization. As a part of this effort, the effects of waste heating that will occur as a result of mixer pump operations are also examined. Finally, the predicted transport behavior of the resulting slurries is compared with the waste acceptance criteria for the Cross-Site Transfer System (CSTS). This work is being performed by Pacific Northwest National Laboratory in support of Westinghouse Hanford Company's W-211 Retrieval Project.We applied the equilibrium chemical code, GMIN, to predict potential chemical reactions. We examined the potential effects of mixing the current tank contents (sludge and supernatant liquid) at a range of temperatures and, separately, of adding pure water at a volume ratio of 1:2:2 (s1udge:supernatant 1iquid:water) as an example of further diluting the current tank contents. The main conclusion of the chemical modeling is that mixing the sludge and the supernate (with or without additional water) in Tank 241-SY-102 dissolves all sodium-containing solids (Le., NaN03(s), thenardite, NaF(s), and halite), but does not significantly affect the amorphous Cr(OH)3 and calcite phase distribution. A very small amount of gibbsite [AI(OH)3(s)] might precipitate at 25"C, but a somewhat larger amount of gibbsite is predicted to dissolve at the higher temperatures. Thus gibbsite precipitation might be avoided at moderate temperatures.within the sludge is saturated with respect to many of the solids species in the sludge, but that the supernatant liquid is not in saturation with many of major solids species in sludge. This indicates that a further evaluation of the sludge mixing could prove beneficial. This type of analysis could provide more detail about the potential chemical reactions and associated rheology changes by incorporating spatial distributions and temporal changes of reactions and kinetics using a model that couples the physical distributions and movements with equilibriumkinetic chemical reactions and associated rheology changes.The chemical constituents and phase distributions predicted by the chemical modeling work were also used to predict the transport behavior of the slurries that will result from sludge mobilization in Tank 241-SY-102. Several properties that impact the anticipated waste acceptance criteria for the CSTS were estimated for each of the cases considered. From these estimates it seems clear that the waste slurry that results from sludge mobilization in 241-SY-102 will have a specific gravity less than 1.2, a mixture viscosity less than 30 cP, and a solids volume fraction less than 0.06. Sedimentation data indicate that the"disp1aced solids volume frac...

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Section: Settled Slurry Volume Fraction and Sedimentation Behaviorsupporting

confidence: 88%

Waste mixing and diluent selection for the planned retrieval of Hanford Tank 241-SY-102: A preliminary assessment

Onishi¹,

Hudson²

1996

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“…6 indicates that the simulated dissipation of excess pore pressure is much slower than the dissipation observed in the experiment. We conjecture that this is due to the formation of vertical channels such as those photographed by Glasrud et al [36], through which the liquid flows upwards at an increased rate compared with its flow through the interstices of the sediment layer. The rapid dissipation of excess pore pressure could also be due to the plastic deformation of the sediment bed at high loads, i.e.…”

Section: Discussionmentioning

confidence: 92%

Applications of the phenomenological theory to several published experimental cases of sedimentation processes

Bürger

Concha

Tiller

2000

Chemical Engineering Journal

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In one space dimension, the phenomenological theory of sedimentation predicts the sedimentation-consolidation behavior of a flocculated suspension in dependence of two constitutive functions describing its material behavior, the solids flux density (or hindered settling function) and the solid effective stress. These functions are assumed to depend only on the local volumetric solids concentration. In this contribution, we review several experimental and theoretical studies of sedimentation in settling columns. We first resume the theories that have been employed to interpret the experimental measurements and then apply the phenomenological model to the available data. The two constitutive functions involved are determined from the published concentration, permeability and effective stress data. The mathematical model is then solved numerically using these functions, and the resulting predictions of settling behavior are compared with the respective authors' experimental findings and interpretations. In one case, the information obtained from a batch settling experiment is used to simulate continuous sedimentation.

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“…2 we show the sedimentation coefficient worked out from [12] after p m (r) was displaced by p(r). A typical value of the Hamaker constant for colloidal particles was chosen, viz.…”

Section: Sedimentation Of Magnetic Particles Affected By Van Der Waalmentioning

confidence: 99%

“…Peterson and Krueger studied the settling velocity of magnetic particles as a function of an applied magnetic field (11). Glasrud et al studied the settling behavior of strongly flocculated magnetic iron oxide particles qualitatively (12). Equations describing the concentration dependence of the sedimentation coefficient without an applied external magnetic field and when the applied magnetic field was infinitely strong were found by Dhont (10).…”

Section: Introductionmentioning

confidence: 98%