Torque-based evaluation of mixing optimization and shear sensitivity during transport of flocculated tailings

Abstract

A modified Couette rheometer is used to simulate mixing of polymer into clayey tailings, and to study the effects of shearing due to pipeline transport. It is found that a normalized torque correlates very strongly with performance indicators measured at the end of mixing and /or shearing, such as CST, oscillatory rheometry, and floc size distribution as inferred from optical microscopy, whether to evaluate a particular mixing strategy, or after simulated pipeline shear. With respect to polymer injection, the torque increases until reaching a peak value after which the torque sharply reduces. This point was found to correspond to the optimal dose, as characterized by the afore-mentioned performance indicators. For clayey tailings, it appears that this technique, as opposed to alternative torque-based techniques used in other industries such as wastewater floc conditioning, produces samples with superior performance indicators at the method-specific optimal dose.