Slurry rheology of Hanford sludge

• Published in: Chemical engineering science 2019-05, Vol.199 (C), p.628-634
• Main Authors: Pease, Leonard F., Daniel, Richard C., Burns, Carolyn A.
• Format: Article
• Language: English
• Subjects: Environmental sustainability; High ionic strength slurries; Polydispersed slurries; Radioactive waste; radioactive waste, high ionic strength slurries, yield stress, polydispersed slurries; Yield stress
• ISSN: 0009-2509; 1873-4405
• DOI: 10.1016/j.ces.2018.12.044

[Display omitted] •Explores rheology of very high ionic strength and polydispersed slurries.•Develops a Cross rheological model inclusive of yield stress.•Demonstrates that radiological waste follows traditional rheology with adjustments. This article evaluates the slurry viscosity of radioactive waste. Hanford waste is a motley mixture of particle sizes and densities composed of metal and oxide particles with constituents spanning much of the periodic table stored at high ionic strength and high pH. Hanford wastes have traditionally been represented as simply an ideal Bingham plastic, but this rheological approximation often provides a poor fit from 0 to 200 1/s, precisely the range of interest for engineering design of waste transport and mixing systems. A modified Cross formulation inclusive of a yield stress is used to fit stress-strain rate data for reconstituted Hanford REDOX sludge waste, measured by increasing shear-rate (up-ramp) and decreasing shear-rate (down-ramp) sweeps. This continuous single equation formulation quantitatively matches experimental data better than other rheological models including the Bingham plastic and Herschel-Bulkley approximations. The increase of viscosity and yield stress from up ramp to down ramp suggests the formation of particle microstructure during shear due to attractive forces.