Houska Based Time-dependent Rheological Model for Flocculated Tailings
Arno Talmon (TU Delft - Offshore and Dredging Engineering, Deltares)
Ebi Meshkati (Deltares)
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Abstract
The rheology of tailings depends on composition and is shear- and time-dependent. Time-dependency might be at the origin of phenomenona such as channel and pattern formation in tailings beaching. Rheology is governed by colloids that form a structure within the fluid. This paper concerns the fitting of the Houska rheological model to controlled stress rheometry data of polymer treated material. The Houska model describes reversible time-dependency, e.g., thixotropy. A novelty here is that irreversible shear down (rheomalaxis) is added to the thixotropy originally captured by the model. The Houska model has the advantage that its time-dependency can be phasewise implemented and tested in numerical codes. In our study, it is shown how the model can be fitted to published detailed controlled shear stress rheometry on flocculated mature fine tailings and is compared with the fitting by a viscosity bifurcation model, which was originally applied. The fits of the viscosity bifurcation model and the current model are comparable. The influence of rheomalaxis on the formation of a lubricating layer in tailings disposal on a beach is investigated by means of a CFD model: flow depth reduces and irregular flow develops.