SLURRY PIPELINE FRICTION LOSSES FOR COARSE AND HIGH-DENSITY INDUSTRIAL-PRODUCTS

Experimental results showed energy-efficient pseudohomogeneous-like fl ow behaviour when a mixture of coarse (20-200 mm) granite rock in tar sand tailings (-1 mm) in mass proportions 1:9 was transported at a tot al volumetric solids concentration of 31% in a 0.44 m i.d. (D) pipelin e loop. Similar results were obtained with an industrially comminuted copper ore (-100 mm; mass median particle size 0.75 mm) when pumped in a 0.2 m i.d. pipe at a concentration of 39%. The partially-stratified friction loss model proposed by K.C. Wilson, G.R. Addie and R. Clift, Slurry Transport Using Centrifugal Pumps, Elsevier, Oxford, 1992 [1] predicted well the observed losses of an iron ore (relative solids den sity 4.1, mass median particle size 0.42 mm) at a concentration of 23% (D=0.1 m). With a slightly heavier and coarser iron ore the model ten ded to underestimate losses at concentrations of 14-29%. The favourabl e friction loss performance in some results may demonstrate how broad particle size distributions and high concentrations may cause reduced pipe wall friction without influence of true rheological mechanisms. A n alternative way of characterizing experimental data in terms of exce ss pressure gradient versus the ratio of mean velocity to hindered set tling velocity is introduced. The flow conditions discussed here corre spond to velocities that clearly exceed those for which there are risk s of deposition at the bottom of the pipe.