Shear Rate-Dependent Rheological Properties of Mine Tailings: Determination of Dynamic and Static Yield Stresses

Abstract

In this paper, shear rate-dependent rheological properties of mine tailings taken from abandoned mine deposits prone to mass movements are examined using a commercial ball-measuring rheological system. The yield stresses (i.e., dynamic and static yield stresses) and viscosity of sand-rich materials are examined by the shear rate-controlled flow curve and time-dependent stress growth methods. Before yielding, the shear stress reaches a peak value (i.e., yield stress) observed for all flow curves. In the steady-state condition, the materials have a minimum shear stress (i.e., dynamic yield stress). The static yield stress can be determined under a constant applied shear rate with different initial values ranging from 10−4 to 10−1 s−1. As a result, the Bingham yield stress and viscosity can be used as a first approximation for estimating the debris flow mobility of post-failure materials. However, the Bingham yield stress is competitive with the static yield stress measured from stress growth methods. Upon comparison of the dynamic and static yield stresses, the static yield stress is approximately 35–45 times greater than the dynamic yield stress, and may be strongly related to microstructural changes (i.e., thixotropy). In this context, special attention must be paid to the determination of yield stresses in debris flow mitigation programs.

Effect of Isomer Composition of Hydroxy Terminated Polybutadiene (HTPB) in Low Shear Flow Behavior (Efek dari Komposisi Isomer dari Hydroxy Terminated Polybutadiene (HTPB) terhadap Sifat Alir dalam Geseran Rendah)

“…It is shown that 1,2-vinyl-rich chain groups (Group A) and 1,4-trans-rich chain groups (Group B) flow under rotational shear with increasing shear rate. A wall slip is suggested to be occurred and divides area into 2 regions as also reported by Jeong et al (Jeong, 2019). Two regions are dark grey (Area 1) and light grey (Area 2).…”

“…The property is identical with HTPB. The behavior is also reported for paint, sand-rich material, kernel oil and coconut oil (Adewale, et al, 2017), (Green, 2004), (Jeong, 2019). Those liquids have hydrocarbon chains similar with HTPB.…”

Thixotropic Behavior of Reconstituted Debris-Flow Mixture

“…The measurement of shear stress depends on the applied initial shear rate, as it is evident in Figure 11 comparing the F22 and F23 tests. The viscous plateau occurs (see Figure 12) independently on the initial applied shear rate (i.e., runs F22, F23 and F24) as it was already observed by Jeon [25], but it disappears as a consequence of aging due to a prolonged resting period.…”

“…The reconstituted debris-flow mixtures at different solid concentrations show a yield stress fluid behavior, characterized by the presence of a static and dynamic yield stress associated with flow starting and stopping [19,24,25]. Recently Quian et al [26] showed they are related to the microstructural material state, whereas Barnes and Walters [27] already pointed out the time dependent property of yield stress.…”

Oral gel loaded with penciclovir–lavender oil nanoemulsion to enhance bioavailability and alleviate pain associated with herpes labialis

“…This further implies that the O3 formulation with greater thixotropy can provide a better-sustained release of PV, easy application at the buccal mucosal surface, as well as an enhanced retention of the gel in the buccal mucosal surface (Lee et al, 2009). The plots for both shear rate and shear stress on logarithmic scales in Figure 5 provide a better delineation of the individual flow curves for further comparison (Jeong, 2019). Specifically, Farrow's constant for the samples was determined from the slope of these plots.…”