Slurry pipeline friction losses for coarse and high density industrial products

Abstract

Experimental results showed energy-efficient pseudohomogeneous-like flow 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 total volumetric solids concentration of 31% in a 0.44 m i.d. ( D) pipeline 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 predicted well the observed losses of an iron ore (relative solids density 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 tended to underestimate losses at concentrations of 14–29%. The favourable 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 theological mechanisms. An alternative way of characterizing experimental data in terms of excess pressure gradient versus the ratio of mean velocity to hindered settling velocity is introduced. The flow conditions discussed here correspond to velocities that clearly exceed those for which there are risks of deposition at the bottom of the pipe.