Variable rheology of heavy mineral tailings - Paterson & Cooke

1412Fluid Consistency Index, K (Pa.s n )10864200% 2% 4% 6% 8% 10% 12% 14|% 16% 18% 20%Volume Fraction of Solids, C v (%)Suction Data Discharge Data Fitted ModelFigure 5. Fluid consistency index versus solids concentration by volume10.90.8flow Behaviour Index, n0.70.60.50.40.30.20.100% 2% 4% 6% 8% 10% 12% 14|% 16% 18% 20%Volume Fraction of Solids, C v (%)Suction Data Discharge Data Fitted ModelFigure 6. Flow behaviour index versus solids vehicle concentration by volumeConclusions• The residue slurry behaves as a time dependent yieldpseudo-plastic fluid i.e. it exhibits shear thinningbehaviour, and the rheology increases with exposure tointense shearing (as in a centrifugal pump)• The rheological parameters have been determined asfunctions of the volumetric concentration of solids• The slurry rheology tends to increase as it passesthrough a pump (increase in yield stress). The increasein rheology is attributed to the generation of fineparticles during shear. This effect is decreasedconsiderably as the density decreases• The rheology of the slurry measured at the discharge ofa centrifugal pump is greater than the rheologymeasured at the discharge of a peristaltic pump on acommon manifold. The difference is attributed to themore intense shear in the centrifugal pump• Finally it is concluded that pumping the residue in ahigh shear pump, such as a centrifugal pump, will notreduce the residue yield stress but rather increase it.ReferencesGOVIER, G.W. and AZIZ, K. The flow of complexmixtures in pipes. Von Nostrand Reinhold Company,1972.166HEAVY MINERALS 2003