Performance of different centrifugal slurry pump impeller configurations when pumping thickened tailings

Abstract

The performance for two tailings products has been investigated with a standard closed shroud impeller (diameter 0.3 m) and an open shroud type having an auger-like inducer. The tailings products had a median particle size of about 70 and 50 µm. For the open impeller reductions in water head and efficiency were 7 and 14% respectively, with the coarser product at solids concentrations by volume of about 47% when operating in the best efficiency region (BEP). The corresponding reductions were about 10 and 20% respectively, for the finer product with a slight tendency of increasing reduction in head for very low flow rates. Unstable head curves were observed for flow rates less than about 50% of the BEP-values with the finer product for the open and closed impeller at 49 and 47% respectively. When operating within the BEP region for these concentrations, the reduction in efficiency was evaluated at about 20% for both types of impellers. The slightly higher sensitivity to an unstable head for low flow rates for the standard closed impeller can be weighted to the 10% higher efficiency compared to the open version with an auger-inducer. The pump performance reduction factors and the pipeline friction losses at a volumetric concentration of 47% were in the order of 1.5 times larger for the finer product. https://papers.acg.uwa.edu.au/p/1104_35_Sellgren/ Performance of different centrifugal slurry pump impeller configurations when pumping A. Sellgren et al. thickened tailings 406

Advances in thickened tailings pumping using centrifugal pumps

“…In the study by Sellgren et al (2011), the suction side pressure was measured at the pump in a 3 m long suction pipeline with a diameter of 0.1 m mounted at the bottom of a vertical cylindrical tank with a diameter of 0.44 m and a height of 1.8 m. Evaluated NPSHA-values at the highest concentration volumetric concentration (49%, slurry density 1,840 kg/m 3 ) in Equation (2) at Q/QBEP values of 60 and 40% were 4.34 and 4.63 m slurry, respectively. The corresponding NPSHR values from the manufacturer's chart were 2.2 and 1.3 m for water.…”

“…The pump used by Sellgren et al (2011) was an all metal pump with a semi-volute shell, 0.1 m diameter suction inlet, 0.075 m discharge and a 0.31 m diameter three-vane impeller. Detailed derating results for the open shroud impeller with an inducer are shown in Figure 3, where the head could not be maintained when C increased from 47 to 49%.…”

“…Performance reductions in head and efficiency from Figures 3 and 4 were therefore extrapolated into the BEP region to be 15 and 20% at a maximum. The study (Sellgren et al, 2011) also covered a coarser tailings product with median particle size 70 µm. The two products had maximum particle sizes of about 400 µm and solids density 2,710 kg/m 3 .…”

“…Evaluated maximum reductions in head and efficiency in the BEP region are summarised in Table 3. Table 3 Summary of experimental performance results for two tailings products with a standard closed shroud impeller and an open shroud type having an auger-like inducer, with impeller diameter 0.31 m (Sellgren et al, 2011). Solids concentration by volume, 45-49%…”

“…The kaolin slurries had yield stresses of 100 and 185 Pa at volumetric concentrations of 17 and 19%, respectively. Kabamba used two standard pumps, one was of the same type and size as used by Sellgren et al (2011), see Table 3 and Figure 4, i.e. an all metal unit with a semi-volute shell, 0.1 m diameter suction inlet, 0.075 m discharge and a 0.3 m diameter three-vane impeller.…”