Proceedings of the 2 nd World Congress on Mechanical, Chemical, and Material Engineering (MCM'16) Budapest, Hungary – August 22 – 23, 2016 Paper No. HTFF 125 DOI: 10.11159/htff16.125 HTFF 125-1 Concentration Distribution of Solid Particles Transported by a Pseudoplastic Fluid Aldo Tamburrino 1 , Gonzalo Montserrat 2 , Christian Ihle 3 1 Associate Professor & Associate Researcher Department of Civil Engineering & Advanced Mining Technology Center University of Chile Av. Blanco Encalada 2002, Santiago 8370449, Chile atamburr@ing.uchile.cl 2 Project Engineer Hydraulics National Institute, Minister of Public Works Av. Concordia 0620, Peñaflor 9750913, Chile gonzalomontserrat@inh.cl 3 Assistant Professor & Associate Researcher Department of Mining Engineering & Advanced Mining Technology Center University of Chile Av. Tupper 2069, Santiago, 8370451, Chile cihle@ing.uchile.cl Abstract - Concentration distributions of solid particles transported by pseudoplastic fluids in laminar regime were determined experimentally. Practically all the distributions show minimum concentration of solids near the centre of the pipe and higher toward the walls and even, for some conditions, the highest values near the top of the pipe. This behaviour of the concentration distribution was explained when diffusive fluxes of the solid particles due to concentration gradient and viscosity gradient are considered. An existing diffusive model was modified in order to take into account negatively buoyant particles and a pseudoplastic fluid as a carrier. It was found that the head loss plays an important role in the fluxes of solid particles due to gradients of concentration and viscosity, increasing them enough to overcome the effect of gravity. Keywords: pseudoplastic fluids, concentration distribution, laminar flow, diffusive fluxes 1. Introduction and Objective The hydraulic transport of solids in pipes is used in many industrial processes, particularly in the mining industry. Usually, it is considered that the flow has to be turbulent to keep the solid particles in suspension, and the upward velocity of the turbulent eddies must be greater than the sedimentation velocity of the particles [1]. Practically all of the studies regarding transport of solids in pipes have been developed using water as a carrier fluid. However, the rheological properties of the solids and water mixture can be modified depending on the concentration and mineralogy of the particles transported by the fluid. Thus, for high concentrations of solids, the particles with smaller size and the water behave as an equivalent non-Newtonian fluid which is the carrier of the larger particles. Studies considering non-Newtonian carriers are comparatively much less than those that considers water or a Newtonian transport fluid [2]. The objective of this article is to report the results of an experimental study regarding the concentration distribution of the solid particles transported by a pseudoplastic fluid in laminar regime and interpret them considering the diffusive fluxes due to gradient of concentration and gradient of viscosity. 2. Experimental Set-up and Materials 2.1. Experimental set-up A sketch of the experimental set-up used in the research is shown in Fig. 1. From the head tank, the slurry is pumped towards the test section by means of two centrifugal pumps EBARA DWO400 connected in series and controlled by a frequency inverter SEW EURODRIVE model MOVITRAC B. The test section consisted in a 12 m long transparent PVC