The flow behavior of concentrated slurry depends on particle size distribution, shape, density, and concentration. The slurry flow behavior can change from Newtonian to non-Newtonian depending on the concentration, slurry composition, and content of fine and especially colloidal particles, which evoke a complex rheological behavior of the slurry. The present article deals with experimental investigation of the flow behavior and pressure drop of dense complex slurries containing sand of different particle size distribution (five different monodispersed and polydispersed sands with mean diameters ranging from 0.20 to 1.40mm), stony dust (mean diameters of 8m and 33m), or clay conveyed in water. The slurries were tested using experimental pipeline loops with inner diameters of 17.5 and 26.8mm. The slurry concentrations range from 6% to 40% for sand slurries, from 26% to 48% for stony dust slurries, and from 45% to 51% for stony dust-sand slurries. The study revealed the time-independent yield pseudo-plastic behavior of the concentrated fine-grained stony dust slurries and the possibility of reducing their flow resistance by adding coarse-grained material. The flow behavior of the stony dust slurries can be approximated by the Herschel-Bulkley or the Bingham model in the laminar region and by the Wilson model in the turbulent region.