Solid-liquid mixtures are encountered in a wide variety of industrial processes, leading to a great deal of interest within the research community in trying to predict and characterise such flows. Classically, slurry flow research has centred on investigating coarse particulate laden flows where an understanding of particle stratification and pressure drop is vital in the design and operation of such processes. Contrasting this is the conveyance of fine/colloidal sized material. Here, stratification of the sediment and pressure gradients during transportation are overshadowed by the rheological influences that begin to dominate during abnormal operation in which the particles are allowed to sediment onto the pipe invert.

Colloidal suspensions are strongly influenced by the particle-particle interaction forces operative in the system, which can govern the bulk behaviour of a sediment bed. The D.L.V.O. theory (Deryagin-Landau and Verwey-Overbeek) represents the total interaction energy between two spherical particles as the summation of the repulsive and attractive forces. Sediment beds within which repulsive forces dominate show different characteristics to beds formed when attractive forces dominate, in terms of the rheology, sedimentation/re-suspension characteristics and sediment bed consolidation levels. This study aims to highlight some of these differences using a variety of techniques, providing comments on how the slurry flow may be influenced.

Keywords: Slurry Flow, Interaction Energy, Rheology