The dependence of plastic flow behavior of clay suspensions on surface properties

Hunter, Robert J.; Nicol, S.K.

doi:10.1016/0021-9797(68)90127-6

Cited by 126 publications

(39 citation statements)

References 10 publications

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“…This is in spite of a number of attempts made, mainly in the 1960s and 1970s, which include the single particle and aggregate network models (Tempel, 1961(Tempel, , 1979, the floc model (Micheals and Bolger, 1962), the elastic floc model (Hunter and Nicol, 1968;Firth, 1976;Firth and Hunter, 1976a,b), and the cell model (Tanaka and White, 1980). As discussed elsewhere (Gupta, 1994;Leong et al, 1995), these models are based on assumptions and premises which are at best questionable.…”

Section: Introductionmentioning

confidence: 92%

Yield stress of suspensions loaded with size distributed particles

et al. 1997

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IntroductionIn particulate processing, the flow of the suspension is critically important to both the energetics and, indeed, to the ultimate success of the unit operation. There are a large number of primary and secondary operations in the minerals and manufacturing industries that fall into this category, and processes such as solids filtration, pumping, and thickening are but three relevant examples to this work. In nearly all particulate processing, the state of dispersion of the particles in the fluid and the volume concentration of particles are important, simply because these two parameters are the prime determinants of suspension viscosity. Concomitantly, the process is more often than not viscosity limited at high solids concentrations.The solids concentration is an easily understood parameter, but the role of the surface chemistry of a particle in particulate processing is less explicitly resolved. For example, in filtration and dewatering operations, the suspension needs to be flocculated to effect the process in a timely manner, however, this in turn results in the suspension exhibiting nonNewtonian flow behavior with increasing solids concentration. The transition concentration is considered classically as the gel point, and flocculated particulate suspensions in excess of this concentration typically exhibit a yield stress. This yield stress is a mechanical rigidity exhibited by the three-dimensional, space filling particulate network, with each particle exhibiting an attractive interparticle force.Yield stress plays an important role in a wide variety of industrial systems and products: the manufacture, storage, and application of paints, dyestuffs, pigments, paper coatings, printing inks, detergents, ceramic slips, carbon pastes, cosmetics, pharmaceutical formulations, and soon, and in the transportation of coal-water slurries, beneficiation of mineral ores and treatment, and disposal of fine particulate wet wastes. Indeed, in many situations pertaining to the processing of flocculated or semistabilized concentrated suspensions, yield stress turns out to be of greater relevance than viscosity. It is also of considerable theoretical interest as yield stress is dependent on the spatial disposition of particles, that is, their structural arrangement in the suspension and the nature and magnitude of the surface forces operating between them (Strenge, 1993). This is distinct from a classical suspension of noninteracting hard spheres, where model considerations negate the forces between particles and the spatial arrangement of particles is most usually geometric. Charged stabilized monodisperse particle suspensions also form crystalline yield stress fluids at a high volume fraction. Both of these examples show a mechanically rigidity as a result of a geometric particle constraints, the gel point of flocculated, ultrasmall particle suspensions may be as low as 5 vol. %. AIChE JournalMay 1997 Vol. 43, No. 5 1171In order to predict the yield stress of a given suspension, as well as extract from the measure...

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Section: Introductionmentioning

confidence: 92%

Yield stress of suspensions loaded with size distributed particles

et al. 1997

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“…Here, the resistance of the suspension to flow can be considered as consisting of two parts, a Newtonian part in which the shear stress is proportional to the shear rate and a nonNewtonian part in which the shear stress is constant irrespective of the shear rate. The Newtonian part has been ascribed to hydrodynamic effects produced by flow of the fluid around the flow units, and the nonNewtonian part has been ascribed to interaction between the flow units (e.g., Hunter and Nicol, 1968). According to rheological theory (Goodeve, 1939(Goodeve, , 1949Gillespie, 1960),…”

Section: Theoretical Considerationsmentioning

confidence: 99%

Rheological Behavior of Na-Montmorillonite Suspensions at Low Electrolyte Concentration

Chen

Cushman

Low

1990

Clays and clay miner.

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Abstract--The prevailing concept that positive-edge to negative-face attraction accounts for the rheological behavior of montmoriUonite suspensions at low electrolyte concentration was investigated. In one experiment, Mg 2+ released from Na-montmorillonite was measured at several NaC1 concentrations; in a second experiment, the viscosity, n, and the extrapolated shear stress, 0, were measured at several clay concentrations, pHs, and NaC! concentrations; and in a third experiment, the absorbance, A, was measured at two wavelengths (450 and 760 nm) at different clay and electrolyte concentrations. The released Mg 2+ decreased with increasing NaC1 concentration until it became zero at a NaC1 concentration between 0.01 and 0.02 M, depending on pH. Thereafter, it increased with increasing NaC1 concentration. Both 0 and n were highly correlated with the amount of released Mg 2+. Also, A remained constant until the NaC1 concentration corresponded to that at the minimum of 0. Thereafter, it increased and became linearly related to 0. These results suggest: (1) positive-edge to negative-face interaction cannot solely account for the rheological properties of montmorillonite at low electrolyte concentration, and (2) the release of octahedral Mg 2+ from montmorillonite affects 0, because it reduces the negative charge on the particles and, thereby, the repulsive force between them.

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“…Also the rheological properties of dense dispersions are correlated with the potential. Hunter and Nicol (4) derived an equation in which the yield stress is a linear function of 2 . The slope is negative; i.e., the maximum yield stress corresponds to the isoelectric point (IEP).…”

Section: Introductionmentioning

confidence: 99%