Developing accurate models for pressure drop in slurry pipelines is one of the most important challenges of researchers around the world. Pressure drop is one of the most important technical parameters to be evaluated by the designer of pipeline slurry transportation system. Also it is the parameter which dictates the selection of pump capacity. The properties of slurries mainly depend on the tendency of the particles to settle out from the carrying liquid. The extent to which the particles will be free to settle in horizontal flow depends on the terminal velocity, the turbulence and particle-particle interaction. Physical models for the prediction of the pressure drop, flow regime, and specific energy consumption are presented. Several studies for pressure drop prediction in slurry flow are available in literature. The comparison between the proposed correlations with the experimental data of the settling slurries is satisfactory. Since the decrease of the specific power consumption and increase overall the transport system efficiency, the carrying capacity should be increased. The experimental investigations were performed on three different sorts of sand solids to satisfy the economic advantage by adjusting the particle size. The experiments were conducted in 26.8 mm inner diameter horizontal pipe on three sizes of sand particles of which mean diameter are 0.2 mm (fine), 0.7 mm (medium) and 1.4 mm (coarse). Flow velocity was up to 7 m/s and overall concentration up to 33% by volume for each velocity. The effect of slurry velocity and particle concentration on the slurry flow behaviour and pressure drop in the turbulent regime was evaluated.