Effect of liquid rheological behaviour on batch sedimentation of coarse spherical particles

Abstract

An experimental study of influence of liquid rheological behaviour on batch sedimentation of coarse spherical particle suspensions is presented. In the experiments, the sedimentation course of assembles of spherical particles settling in a Plexiglas column of rectangular cross-section in creeping flow region was video recorded and the video sequences were evaluated visually and using an image analysis. The particles used were closely monodispersed glass spheres of diameter 1.92 and 4.12 mm. The range of initial mena volume fraction of solid in suspensions tested was from 0.05 to 0.40. Dispersing liquids tested were aqueous solutions of glycerol (Newtonian fluid) and solutions of methylcellulose Tylose MH 4000, hydroxyethylcellulose Natrosol 250 MR, and polyethylene oxide Polyox WSR 301. The basic tool used for image processing and analysis was commercially available software Screen Measurement M. The creation of different zones of particles was detected during sedimentation. The form and time development of these zones depend on the rheological behaviour of the fluid, particle diameter, and initial concentration of suspension.