Rheology Modifiers Applied to Kaolin-Bentonite Slurries for SRNL WTP Pulse Jets Tank Pilot Work in Support of RPP at Hanford
Savannah River National Laboratory (SRNL) was tasked to find and characterize the impact of rheological modifiers to a clay (Kaolin-Bentonite) slurry having 23.1 total wt percent solids, 1.165 g/ml, and Bingham Plastic yield stress of 13 Pa and plastic viscosity of 24 mPa-sec. The primary objective was to find rheological modifiers when blended with this clay slurry that would provide a vane yield stress of 300 Pa when the slurry was undisturbed for 24 hours. A secondary objective was to find a modifier that after shearing would produce a Bingham Plastic yield stress of 30 Pa and plastic viscosity of 30 mPa-sec. Two parallel paths were chosen with one examining a variety of organic/inorganic modifiers and another using just the inorganic modifier Laponite (R). The addition of organic modifiers hydroxyethylcellulose, hydroxypropylmethylcellulose, and hydroxypropylcellulose at a target 0.50 wt percent dramatically increased the vane yield stress over the range 311 - 724 Pa, and also increased the Bingham plastic yield stress and plastic viscosities over the range 33-112 Pa and 27-166 mPa-sec, respectively. The organic modifiers also showed elastic behavior, yielding a very unpredictable up flow curve. The 0.50 wt percent addition of inorganic modifiers magnesium aluminum silicate and hydrate magnesium aluminum silicate only increased the vane yield stress to 36-46 Pa and had little impact on the Bingham Plastic parameters. A range of an inorganic (2-4 wt percent magnesium aluminum silicate) and combination of a range of an inorganic (2-3 wt percent magnesium aluminum silicate) and organic (0.03-0.05 wt percent sodium carboxymethylcellulose) modifiers were then tested. These results showed that the target vane yield stress could be obtained but the Bingham Plastic yield stress and plastic viscosity were 3 times too high. Reducing the organic modifier weight percent by a few hundredths, the Bingham Plastic yield stress could be obtained, but then the vane yield stress would be too low. The addition of Laponite (R) (synthetic lithium aluminum silicate) increased the vane yield stress of the clay slurry to values as high as 1500 Pa. However, the flow curve behavior for the laponite samples was not predictable and the secondary objective was dropped based on customer needs and time constraints. Ultimately a 3-wt percent addition of Laponite (R) was chosen to produce a 600 Pa vane yield stress mixture.
- Research Organization:
- Savannah River Site (SRS), Aiken, SC (United States)
- Sponsoring Organization:
- US Department of Energy (US)
- DOE Contract Number:
- AC09-96SR18500
- OSTI ID:
- 837897
- Report Number(s):
- WSRC-MS-2005-00111; TRN: US0501287
- Resource Relation:
- Conference: AIChE Spring 2005 Conference, Atlanta, GA (US), 04/10/2005--04/14/2005; Other Information: PBD: 9 Feb 2005
- Country of Publication:
- United States
- Language:
- English
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