Sun, YS, McGowan, D, Byrne, Y, Parkinson, D & Kaminsky, H, DeJong, J 2026, 'In situ measurement of fluid fine tailings rheology', in AB Fourie, M Horta, M Oliveira & S Wilson (eds), Paste 2026: Proceedings of the 28th International Conference on Paste, Thickened and Filtered Tailings, Australian Centre for Geomechanics, Perth, pp. 1-15, https://doi.org/10.36487/ACG_repo/2655_21
(https://papers.acg.uwa.edu.au/p/2655_21_Sun/)
Abstract: Understanding the viscosity and yield stress of fluid fine tailings is essential for effective computational fluid dynamics modelling in the oil sands industry. These rheological properties influence key processes such as paste interaction with sand deposition, dredging operations, and containment failure analysis. However, obtaining representative measurements of these properties is challenging. Due to their sensitivity to shear history, the rheological properties of fluid fine tailings can undergo irreversible changes during sampling and transport, leading to non-representative data generated at significant costs.
This study introduces a modified rheological testing method using a patent pending variable-rate vane shear testing apparatus (VR-eVST). In situ field tests were conducted at 9 distinct locations within a tailings containment facility near Fort McMurray, Alberta, Canada. When deployed directly in the tailings deposit, the initial VR-eVST results indicate that in situ rheological properties may be significantly higher than those obtained from laboratory measurements performed after sampling and transport.
At each location, fluid tailings were also sampled for parallel ex situ testing using both the VR-eVST and a laboratory concentric cylinder rheometer. Under the tested conditions, the tailings exhibited Bingham plastic behaviour, with strong agreement between the 2 geometries. The results confirmed that samplinginduced shearing can lead to significant underestimation of rheological properties.
Planned further study includes exploring alternative rheological models, refining the equipment design to constrain the shear boundary, and expanding testing to a broader range of tailings types. This earlystage research demonstrates the potential of the VR-eVST method to moreaccurately measure the in situ rheological properties of fluid fine tailings, ultimately leading to improved facility management and safety. 

Keywords: rheology, fluid fine tailings, in situ measurements, Bingham fluid properties, oil sands, tailings management, dredging