Effect of pipe inclination on the deposition velocity of settling slurries

Experiments were conducted using a 100 mm diameter pipe loop to investigate the deposition velocity (Vc) of settling slurries in inclined pipe flows up to 20° (36.4 %). Slurries which comprised silica sand or gravel (0.1–8 mm) and water were tested at solids concentrations between 6–40 % by volume (0.06–0.4 L/L). For the fine (d ∼0.1 mm) and intermediate solids (d ∼0.19 mm, 0.3 mm), increases in Vc with pipe inclination were marginal. For the coarsest solids (2 and 8 mm gravel), the deposition velocity increased significantly with pipe inclination. A comparison is made with the results of Wilson and Tse. The effect of inclination is correlated with the efficiency of turbulent suspension of the particles.