Effect of colloidal aggregation on the sedimentation and rheological properties of tank waste

Rector, David R.; Bunker, Bruce C.

doi:10.2172/113874

Cited by 24 publications

(34 citation statements)

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“…32,33 ) which is indeed observed in the experiment. Further acidising is supposed to generate positively surface charged and hence well dispersed particles.…”

Section: Synthesis Parameterssupporting

confidence: 81%

Morphology and Agglomeration Control of LiMnPO₄ Micro- and Nanocrystals

et al. 2013

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Microwave-assisted hydrothermal synthesis was used to grow LiMnPO 4 micro-and nanocrystals from acetate precursors. By appropriate adjustment of the precursor concentration and the pH-value of the reactant, the product composition and purity along with the crystal size can be manipulated, resulting in particle-dimensions from around 10 µm down to a few 100 nm. Prisms and plates with hexagonal basal face as well as cuboid and rod-like particles were produced. The effects on the crystal morphology as well as on the materials texture and agglomeration tendency are discussed and a comprehensive agglomeration phase diagram is constructed.

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“…32,33 ) which is indeed observed in the experiment. Further acidising is supposed to generate positively surface charged and hence well dispersed particles.…”

Section: Synthesis Parameterssupporting

confidence: 81%

Morphology and Agglomeration Control of LiMnPO₄ Micro- and Nanocrystals

et al. 2013

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“…When primary particles are small, normally less than 20 μm for Hanford waste, they tend to flocculate and form agglomerates (Rector and Bunker 1995a). Although the agglomerate density, which includes the interstitial liquid, is less than the primary particle density, agglomerates usually settle faster than primary particles (MacLean 1999).…”

Section: Solids Floc and Agglomerate Settlingmentioning

confidence: 99%

Hanford Waste Physical and Rheological Properties: Data and Gaps

Wells¹,

Kurath²,

Mahoney³

et al. 2011

103

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Executive SummaryThe Hanford Site in Washington State manages 177 underground storage tanks containing approximately 250,000 m 3 of waste generated during past defense reprocessing and waste management operations. These tanks contain a mixture of sludge, saltcake and supernatant liquids. The insoluble sludge fraction of the waste consists of metal oxides and hydroxides and contains the bulk of many radionuclides such as the transuranic components and 90 Sr. The saltcake, generated by extensive evaporation of aqueous solutions, consists primarily of dried sodium salts. The supernates consist of concentrated (5-15 M) aqueous solutions of sodium and potassium salts. The 177 storage tanks include 149 single-shell tanks (SSTs) and 28 double-shell tanks (DSTs).Ultimately the wastes need to be retrieved from the tanks for treatment and disposal. The SSTs contain minimal amounts of liquid wastes, and the Tank Operations Contractor is continuing a program of moving solid wastes from SSTs to interim storage in the DSTs. The Hanford DST system provides the staging location for waste feed delivery to the Department of Energy (DOE) Office of River Protection's (ORP) Hanford Tank Waste Treatment and Immobilization Plant (WTP). The WTP is being designed and constructed to pretreat and then vitrify a large portion of the wastes in Hanford's 177 underground waste storage tanks.The retrieval, transport, treatment and disposal operations involve the handling of a wide range of slurries. Solids in the slurry have a wide range of particle size, density and chemical characteristics. Depending on the solids concentration the slurries may exhibit a Newtonian or a non-Newtonian rheology.The extent of knowledge of the physical and rheological properties is a key component to the success of the design and implementation of the waste processing facilities. These properties are used in engineering calculations in facility designs. Knowledge of the waste properties is also necessary for the development and fabrication of simulants that are used in testing at various scales. The expense and hazards associated with obtaining and using actual wastes dictates that simulants be used at many stages in the testing and scale-up of process equipment. The results presented in this report should be useful for estimating process and equipment performance and provide a technical basis for development of simulants for testing.The purpose of this document is to provide an updated summary of the Hanford waste characterization data pertinent to safe storage, retrieval, transport and processing operations for both the tank farms and the WTP and thereby identify gaps in understanding and data. Important waste parameters for these operations are identified by examining examples of relevant mathematical models of selected phenomena including: The data sets in (UDS composition and particle density, UDS primary particle size and shape, UDS particle size distributions [PSDs], and estimated particle size and density distributions [PSDDs]) and Poloski et al. (2007) ...

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“…The first step in understanding the potential for heel development from normal sludges is to address the colloidal chemistry of such materials (Rector and Bunker, 1995). On a mass balance basis, sludges are predominantly mixtures of hydrous iron and aluminum oxides, with a large percentage of entrained pore fluid, "supernate".…”

Section: Theoretical Considerationsmentioning

confidence: 99%

“…A fiu-ther complication is, that under laboratory testing, sludge characteristics may change in response to changing experimental environments (Rector and Bunker, 1995). Large aggregate particles formed in concentrated colloidal suspensions can break down when the colloid loading is lowered.…”

Section: Theoretical Considerationsmentioning

confidence: 99%

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Occurrence, Characterization and Synthesis of Hanford and SRS Tank Heel Materials

Krumhansl¹

2002

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The long-range objective of this study was to develop chemically assisted technologies for removing heels from tanks. In FY 01, the first two steps toward this objective were taken: (1) catalogue the occurrence and nature of tank heels and assess which materials are available for study and (2) develop methods for synthesizing non-radioactive surrogate heel materials for use in testing potential removal technologies.The chief finding of Task 1 was the existence of "heels", depending on the definition used. Hard materials that would be almost impossible to remove by sluicing are all but absent from the records ofboth Savannah River and Hanford. Historical usage suggests that the term "heel" may also apply to chunky, granular, or semi-solid pasty accumulations. These materials are documented and may also be difficult to remove by conventional sluicing technologies. Such heels may be comprised of normal sludge components, dominantly iron and aluminum hydroxides, or they may result from added materials which were not part of the normal fuel reprocessing operations: Portland cement, diatomaceous earth, sand and soil and spent zeolite ion exchange "resins". The occurrence and chemistry of the most notable "heel", that of the zeolite mass in Tank 19F at Savannah River, is reviewed in some detail. Secondly, no clear correlation was found between high tank temperatures and difficulties encountered in removing materials fiom a tank at a later date; nor did the sludges fiom these tanks give any indication of being particularly solid.Experimental studies to develop synthetic heel materials were caned out using a number of different approaches. For normal sludge materials settling, even when assisted by a centrihge, it proved ineffective. The same result was obtained from drylng sludge samples. Even exposing sludges to a molten salt melt at 233' C, only produced a fine powder, rather than a resilient ceramic which resisted disaggregation. A cohesive material, however, was produced by wicking the pore fluid out of a sludge gel (into packed diatomaceous earth), while simultaneously applying pressure to compact the sludge as it dehydrated. Osmotic gradients could provide the same fimction as the capillary forces provided by the diatomaceous earth sorbant placed in contact with the sludge. Tests on the anomalous materials added to the tanks all indicated potential problems. Hard granules, and maybe chunks, may be encountered where Portland cement was added to a tank. Sand, spent zeolite resin, and diatomaceous earth, will all react with the tank fluids to produce a sodalite/cancrinite material. The degree of reaction determines whether the grains become cemented together. SRS activities showed that heels formed when spent zeolites were added to 3 tanks can be readily dislodged and it is expected that heels from sand would possess equal or less cohesion. Diatomaceous earth may f o m more resilient crusts or masses.To summarize, the existence of "hard" heels has yet to be documented. A broader definition suggests inclusion ...

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Effect of colloidal aggregation on the sedimentation and rheological properties of tank waste

Cited by 24 publications

References 11 publications

Morphology and Agglomeration Control of LiMnPO₄ Micro- and Nanocrystals

Morphology and Agglomeration Control of LiMnPO₄ Micro- and Nanocrystals

Hanford Waste Physical and Rheological Properties: Data and Gaps

Occurrence, Characterization and Synthesis of Hanford and SRS Tank Heel Materials

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Effect of colloidal aggregation on the sedimentation and rheological properties of tank waste

Cited by 24 publications

References 11 publications

Morphology and Agglomeration Control of LiMnPO4 Micro- and Nanocrystals

Morphology and Agglomeration Control of LiMnPO4 Micro- and Nanocrystals

Hanford Waste Physical and Rheological Properties: Data and Gaps

Occurrence, Characterization and Synthesis of Hanford and SRS Tank Heel Materials

Contact Info

Product

Resources

About

Morphology and Agglomeration Control of LiMnPO₄ Micro- and Nanocrystals

Morphology and Agglomeration Control of LiMnPO₄ Micro- and Nanocrystals