Continuous rheometry for industrial slurries

Mineral solids are usually processed, produced or handled in the form of two-phase slurries. Accurate and reliable measurements of the rheological properties of settling slurries using conventional viscometric instruments can be difficult, if not impossible, since the solid particles settle rapidly under the influence of gravity. In this paper we report on the development of an on-line flow rheometer specially designed and constructed for characterising the rheological behaviour of settling slurries. The instrument design is based on the principles of helical flow, which is the combination of tangential Couette and axial Poiseuille flows. The data reduction procedure developed is firmly based on the theory of helical flow and has been extensively tested and validated with fluids of different rheological behaviour. Good results have been obtained using the rheometer for various Newtonian liquids, pseudoplastic polymeric solutions and mineral slurries.