Analysis of suspension sedimentation in fluids with rheological shear-thinning properties and thixotropic effects

Suspension sedimentation in fluids with shear-thinning properties is of interest in several industrial operations, such as oil and gas exploration. This paper offers new information about the behavior of a group of particles settling in shear-thinning fluids. The tests carried out in this work differ from those reported in earlier works, because they involved a quantitative analysis of the settling behavior of particulate materials in regions with high concentrations of solids (where sediment is formed). To this end, the gamma-ray attenuation technique was used to monitor the concentration of solids in different regions of the tube over time. The results revealed significant differences in the behavior of particles settling in Newtonian and non-Newtonian fluids. Sediment was formed faster in the shear-thinning fluid when compared to the Newtonian fluid of similar apparent viscosity. However, final sediment compaction took longer in the non-Newtonian fluid. Overall, this study provides relevant information about sedimentation in non-Newtonian fluids, and addresses a subject about which several aspects should be further explored and better understood. (C) 2016 Elsevier B.V. All rights reserved.