| 1. |
- Addie, Graeme R., et al.
(author)
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Design, selection, sizing and control considerations for cyclone feed slurry pumps
- 1999
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In: Powder Technology. - 0032-5910 .- 1873-328X. ; 104:3, s. 233-239
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Journal article (peer-reviewed)abstract
- Cyclone feed centrifugal slurry pumps in semi-autogenous grinding (SAG) mill and other cyclone feed circuits see coarse size slurries at high concentrations that can result in high wear if the pump is not designed, selected, sized and operated correctly. The high proportion of static head of the normal cyclone feed circuits usually results in a relatively flat system curve which in conjunction with the typically flat slurry pump curve results in large changes in operating flow with small changes in system head. When this is combined with the normal (or abnormal) fluctuations in the output from the mill upstream of the pumps, any shortcomings in the pump control system and/or matching of the pump means large fluctuations in flow and increased wear. This difficulty could be corrected by continuous variations in speed. A means of control by which the speed is changed in an appropriate way is suggested here. In this case then the pump-input power, the known water performance of the pump and the system flow, can be used to calculate an effective pump discharge pressure. By comparison with a calculated system head, the pump speed can be regulated such that the pressures are equal and the system stable for any practical variation of incoming flow or specific gravity.
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| 2. |
- Sellgren, Anders, et al.
(author)
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Cost-effective pumping of coarse mineral products using fine sands
- 1997
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In: Powder Technology. - 0032-5910 .- 1873-328X. ; 94:3, s. 191-194
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Journal article (peer-reviewed)abstract
- Coarse mineral particles with sizes of up to 200 mm can be pumped energy-effectively together with sands (< 1 mm) under nearly pseudohomogeneous conditions at volumetric solids concentrations of up to 40%. Recent experimental results indicate that particles with sizes of 0.1-0.5 mm play an important role in reducing pipe wall friction. Experimental results in pipelines with diameters of up to 0.44 m have here been used in a brief demonstration of industrial applications: integrated systems for waste rock transportation together with fine-grained tailings, coarse mineral particle pumping from open-pit mines or to disposal with dry deposition and recirculation of water and fine particles. Experiments with a crushed rock product (20-38 mm) pumped at a volumetric concentration of 13% showed that the friction losses were reduced considerably by particle degradation during the circulation in the pipeline loop. Circulatory effects must therefore be carefully considered when using coarse-particle loop results in the design of industrial once-through systems
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| 3. |
- Sellgren, Anders, et al.
(author)
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Effects of non-Newtonian mineral suspensions on the performance of centrifugal pumps
- 1999
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In: Mineral Processing and Extractive Metallurgy Review. - : Informa UK Limited. - 0882-7508 .- 1547-7401. ; 20:1, s. 239-249
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Journal article (peer-reviewed)abstract
- Experimental results were obtained with various industrial suspensions with densities of 1100 to 1600 kg/m3 using a 0.15 by 0.1 m four-vane centrifugal slurry pump with an impeller diameter of 0.63 m operating at 650-850 rpm. The non-Newtonian behaviour for a fixated scrubber sludge and a red mud product was characterised in pipeline loops with diameters of 0.075-0.2 m. The lowering of the pump water head and efficiency at the best efficiency flow rate region was at a maximum about 10 and 20%, respectively. With the scrubber sludge, a sharp reduction in head occurred at flow rates below 40% of the best efficiency value, resulting in an unstable head curve. This result is used to demonstrate the risk of unstable operation if a Newtonian correction procedure with a high viscosity is applied giving very large reductions in efficiency and a shift of the best efficiency point to smaller flow rates
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| 4. |
- Sellgren, Anders, et al.
(author)
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Integrated approaches to mine waste handling with slurry pumping
- 1995
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In: Sudbury '95, mining and the environment. - Sudbury : Laurentian University. - 0660160439 ; , s. 1089-1094
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Conference paper (peer-reviewed)abstract
- The feasibility of slurry pumping for handling and disposal of mine waste is considered. The method is cost effective for waste rock with particle sizes of 100 to 200 mm. In an example taken from the literature, the investment needed for a slurry pumping waste disposal system is calculated to be less than half that required for a conveyor belt system. In an integrated system based on slurry transport of coarse and fine particles, the additional cost of transporting wet rock together with the wet fine-grained tailings is a fraction of the cost of handling the tailings alone. The system can be integrated with a flooded area for reactive waste.
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| 5. |
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| 6. |
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| 7. |
- Sundqvist, Åsa, et al.
(author)
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Pipeline friction losses of coarse sand slurries. Comparison with a design model
- 1996
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In: Powder Technology. - 0032-5910 .- 1873-328X. ; 89:1, s. 9-18
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Journal article (peer-reviewed)abstract
- Friction losses in 0.2-0.3 m i.d. pipelines were investigated for three coarse sands with mass median particle sizes of 0.6-0.7 mm and size distributions of 1.4, 5.4 and 27.3, respectively, when expressed in terms of the ratio of particle diameters 85 to 15% by mass finer. 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 the observed friction losses reasonably well at volumetric concentrations of 12-15% for velocities of practical interest. Good agreement was found for concentrations of up to 31% for sand with the intermediate distribution. However, predictions for the narrowest sand underestimated friction losses at higher concentrations of 26-31%. Friction losses for the broadest sand were overestimated markedly at concentrations of 28-39%. With these two sands, observed losses did not increase linearly with concentration, in disagreement with model assumptions. The different mechanisms involved are discussed in light of results demonstrating how particle size distribution, content of particles 0.1-0.5 mm in size, and concentration affect friction losses. 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.
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| 8. |
- Sundqvist, Åsa, et al.
(author)
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Slurry pipeline friction losses for coarse and high density industrial products
- 1996
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In: Powder Technology. - 0032-5910 .- 1873-328X. ; 89:1, s. 19-28
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Journal article (peer-reviewed)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.
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