Concentration profiles for six particle sizes ranging from 38 to 739 mum were measured using a traversing mechanism and isokinetic sampling probe at nine levels in the vertical plane for multisized particulate zinc tailings slurry flowing through 105 mm diameter horizontal pipe. Experiments were conducted at three flow velocities of 2, 2.75 and 3.5 m/s using five efflux concentrations ranging from 4% to 26% by volume for each velocity. Solids concentration profiles were found to be a function of particle size, velocity of flow and efflux concentration of slurry. Solids concentration varied with the vertical position, except for particle size of 38 mum. Experimental data for pressure drop were also collected at five efflux concentrations ranging from 4% to 26% at flow velocities ranging from 1.2 to 4.0 m/s for each efflux concentration. Karabelas model for solids concentration profiles and Wasp model for pressure drop have been modified by alleviating some of the restrictive assumptions used in the models. The modified models are compared with the experimental data collected in the present study and show good agreements. Comparison of pressure drop data with the predictions by two layer model is also satisfactory. (C) 2002 Elsevier Science Ltd. All rights reserved.