The Role of Rheology in the Pipelining of Mineral Slurries

This paper combines new experimental evidence and pipeline flow models to challenge widely held views in the literature. These include the existence of a yield stress and its determination, the existence of shear-thinning at high shear rates, and the continuum approximation which is routinely applied to these slurries. The implications of these critical points for laminar, laminar/turbulent transition and turbulent flow are investigated. It is shown that interpretation of rheological data at low and high shear rates is crucial for flow modelling in all three types of flow. It is concluded that the yield pseudoplastic model should be used for mineral slurries and low shear rate phenomena may be ignored. A high shear rate asymptote was not found or deemed necessary. The yield stress is fundamentally important for the laminar/turbulent transition and results in the critical velocity becoming independent of pipe diameter. Accurate rheology is important in smooth turbulent flow. Rough turbulent flow requires a particle roughness effect and is independent of rheology.