The Hydraulic Institute has completed the task of developing a new ANSI/HI standard 12.1-12.6 (2005) for rotodynamic (centrifugal) slurry pumps covering nomenclature, definitions, applications, and operation. The standard provides examples of the different slurry pump types and contains an extensive section on pump and slurry definitions. The effect of slurry on pump performance is covered along with the pumping of froth. Reference is also made to ANSI/HI standard 9.6.7 (2004), which contains a new method for pump performance correction when handling viscous fluids. Classification of slurry services is established and then is used to determine limitations on velocities and total head per pump in order to obtain acceptable wear performance. The new service class, head per stage and other limits are directly related to capital and other cost considerations that will affect solids transport system economics. The writers review the contents of the new standard, highlight the main points, and discuss the reason for the slurry classification, corresponding limits and expected implications, particularly with respect to operating costs of the pumps in solids transport systems

There is a wide variety of industrial pastes or non-settling slurries pumped in mining, dredging and reclamation projects as products, refuse and tails. The types and/or names of some of the common ones are alumina red mud, phosphate clays, tar sands mature fine tails, tar sands (CT) consolidated clays and fly ash. The pipeline performance or friction of these varies dramatically with the type, its concentration and the particulars of the actual slurry making it difficult to select pumping equipment and to design associated pipelines. The GIW Hydraulic Laboratory in Grovetown Georgia has tested a number of these slurries over the last 30 years for various mining customers. Where available in the public domain and/or where permission has been obtained, the results of those tests are presented in this paper in a form usable for pipeline and pump system designers and users.

The Hydraulic Institute has completed the task of developing a new ANSI/HI standard 12.1-12.6 (2005) for Rotodynamic (Centrifugal) Slurry Pumps covering nomenclature, definitions, applications, and operation. The standard provides examples of the different slurry pump types and contains an extensive section on pump and slurry definitions. The effect of slurry on pump performance is covered along with the pumping of froth. Reference is also made to ANSI/HI standard 9.6.7 (2004), which contains a new method for pump performance correction when handling viscous fluids.Classification of slurry services is established and then is used to determine limitations on velocities and total head per pump in order to obtain acceptable wear performance. The new service class, head per stage and other limits are directly related to capital and other cost considerations that will affect solids transport system economics. The writers review the contents of the new standard, highlight the main points, and discuss the reason for the slurry classification, corresponding limits and expected implications, particularly with respect to operating costs of the pumps in solids transport systems.

The Hydraulic Institute has just completed the task of developing a new ANSI/HI standard on Rotodynamic (Centrifugal) Slurry Pumps covering nomenclature, definitions, applications, and operation. The standard provides examples of all the different types of pumps available and has an extensive section on definitions. Slurries and their effect on performance and wear are covered. A slurry service class is established which then is used to limit velocities and head produced per pump to give acceptable wear. A special section deals with mechanical seals and a new method for determining flange loads is presented and guidelines are given for commissioning, start-up etc.The head limits and the performance derating are of special interest when centrifugal slurry pumps are applied to thickened tailings and paste-like slurries. For Newtonian liquids, the Hydraulic Institute's Viscosity Correction Method (ANSI/HI 2004) provides a procedure widely used for viscous effects on the performance. For the homogeneous flow of viscous slurries, the new slurry standard refers to an applicable viscosity to use with the method and to "consult the pump manufacturer for guidance regarding non-Newtonian slurry pump performance."Experimental performance results are presented here and applied to the viscosity correction method for a simulated tailings product slurry characterized by a fully sheared yield stress of about 100 Pa, evaluated from pipeline data. The pump was a GIW-LCC type three-vane all metal unit with a 0.3m-diameter impeller having an open shroud with a simple auger-like inducer. Results are also given for an underground hydraulic fill product characterized by a Newtonian kinematic viscosity which is 1300 times that for water. The different results obtained here point out the strong influence the rheological behavior has on the choice of pump size and the power requirement.

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.

River flows with high volume concentrations (20-50%) of silty sediments generally imply that the mixture has non-Newtonian properties. In this study, the rheological behavior of mixtures with solids particles smaller than 0. 1 mm was identified experimentally with viscosimeters. Characteristic flow parameters, such as energy losses and depths, were then determined in several examples for turbulent open channel flows.

A system-oriented development project has been started by the LKAB mining company and Chalmers University of Technology (CTH), in co-operation with manufacturers and inventors. The development work has concentrated on improvements of some components and better understanding of specific problems, which, seen together, are believed to be of great interest in slurry transportation applications. So far, a rubber-lined plastic pipe for high-pressure applications has been developed, and a high-pressure pump without large external devices and with a minimum of moving parts is to be patented. Simultaneous laboratory and in-plant tests of the new components have been started, and studies on freezing problems, chemical additives, and secondary flow have also been carried out. A pilot-plant investigation on hydraulic hoisting of heavy ore by centrifugal pumps has been completed at CTH.

Tests were performed in the GIW Hydraulic Laboratory on a milled copper slag tailings slurry in pipe loops with 75 and 100 mm diameter loss sections. Volumetric concentrations of 1 to 14% were tested in the 100 mm loop, and the initial results, derived using magnetic flow meter measurements, showed pressure losses approximately equal to that of water. Chemical Testing of the solid particles was performed, and they were found to be made up of 56% magnetite by weight. Magnetite has been found in the past (Sonar Trac paper) to effect magnetic flow meter measurements, which was the primary method being used in this test program. Secondary measurements using a Sonar Trac instrument indicated, in contrast, the more common and expected equivalent fluid behavior in the 4” loop at the lower concentrations, where the losses, when expressed in height of slurry, now landed on top of the carrier liquid curve, which was found to be equal to that of water. A comparison between the measurements from the magnetic flow meter, and those from the sonar trac, showed a linear dependency between the flow rate ratio (between the magnetic flow meter measurement and the sonar trac measurement) and the solids concentration. These tests illustrate the importance of having knowledge of the makeup of the solid particles in a slurry, and the utility of acoustic based flow rate measurement methods in cases where magnetite (or other solids particles with magnetic properties) particles are present within the slurry.

Recent loop testing performed at the GIW Hydraulic Lab (Furlan et al. 2013, 2014) has provided pump performance data for two highly non-Newtonian slurries of significantly different character: a high clay content slurry with minimal coarse solids; and a typical, low clay content, two component tailings slurry. The importance of air removal in the sump and pipe loop was demonstrated using a simple, yet novel de-aeration system. In addition to the measurement of performance losses, determination of the upper limit of "pumpability" for these slurries relative to their concentration and associated yield stress was investigated. However, once the slurry was de-aerated, no limits could be found, other than those dictated by suction side losses (NPSHA) or excessive pipeline friction gradients, indicating that the only true limit in practice is one of system economics, i.e. pump operating and capital cost. Experimentally measured pump head and efficiency were compared against corresponding predictions from two different models: the Walker and Goulas technique (Walker and Goulas, 1983), and the Graham et al. technique (Graham et al., 2009), with special focus given to the dependence of the losses on pump rotary speed.

Recent loop testing performed at the GIW Hydraulic Lab (Furlan et al. 2013, 2014) has provided pump performance data for two highly non-Newtonian slurries of significantly different character: a high clay content slurry with minimal coarse solids; and a typical, low clay content, two component tailings slurry. The importance of air removal in the sump and pipe loop was demonstrated using a simple, yet novel de-aeration system. In addition to the measurement of performance losses, determination of the upper limit of "pumpability" for these slurries relative to their concentration and associated yield stress was investigated. However, once the slurry was de-aerated, no limits could be found, other than those dictated by suction side losses (NPSHA) or excessive pipeline friction gradients, indicating that the only true limit in practice is one of system economics, i.e. pump operating and capital cost. Experimentally measured pump head and efficiency were compared against corresponding predictions from two different models: the Walker and Goulas technique (Walker and Goulas, 1983), and the Graham et al. technique (Graham et al., 2009), with special focus given to the dependence of the losses on pump rotary speed.

Pipe flows of bimodal settling slurries exhibit frictional head losses quite different from those determined simply as a sum of loss contributions by the individual fractions. Mechanisms governing flow friction and resulting from an interaction of grains of different fractions in transported slurry are not well understood. This makes a prediction of the frictional head loss in flows of bimodal slurries with Newtonian carrier uncertain. An extensive experimental campaign was conducted in GIW Hydraulic Laboratory in 2016 with slurries of four narrow graded fractions of the virtually same grain densities and very different grain sizes (carrier-liquid fraction, pseudo-homogeneous-, heterogeneous-, and stratified fractions). Besides testing of the individual fractions, different combinations of the fraction mixtures (bimodal, three- and four-component) were tested as well. In our previous work published in 2018, we employed experimental results for bimodal slurry composed of coarse granite rock (the stratifiedfraction) and fine sand (the pseudo homogeneous fraction) to analyze the observed considerable reduction of the frictional head loss caused by an addition of the fine sand to the granite rock slurry. In this work, we extend our analysis to the other bimodal slurries composed of permutations of the four fractions (in total 3 additional bimodal slurries) with a major objective to identify possible mechanisms leading to a modification of the frictional head loss due to an addition of a finer fraction to a coarser mono-disperse slurry, and to quantify this effect for the purposes of a predictive four-component model (4CM). The investigation shows that the frictional loss of bimodal slurry is always smaller than the theoretical loss obtained as the sum of losses of the fractions, although the massive reduction observed in the slurry composed of the stratified rock and fine sand is not observed in any other bimodal slurry. The investigation also suggests that the friction effect obtained by the finer fraction addition is due to different mechanisms for different bimodal slurries although all mechanisms are associated with altering mechanical friction due to granular contacts. It is shown that the observed effects can be well reproduced by the friction loss model 4CM, calibrated by the experimental data set from the 203-mm pipe and validated by the data set from the 103-mm pipe.

Transported Newtonian settling slurries (mixtures of solid particles and carrying liquid) tend to stratify in a slurry pipeline and the degree of their stratification significantly affects the frictional head loss in a pipeline system. Solid particles can span a broad range of sizes from those typical for fine sand to those typical for coarse gravel. Different fractions of solids have different properties and form different flow patterns. The different patterns are associated with different dominating particle support mechanisms and friction mechanisms in slurry flow. Hence, there are different models describing and predicting the frictional head loss in pipe flows of different settling slurries. In the presented work, we focus on friction-loss models for heterogeneous (partially-stratified) flow (V₅₀-model), and for fully-stratified flow (V_sm-model). The models can serve as tools to scale up information on frictional head loss in flow of specific slurry obtained experimentally in a small laboratory pipe to larger pipes of industrial sizes. So far, the reliability of the scale up has been difficult to verify as an availability of coarse particle experimental data was restricted to small laboratory pipes (an internal diameter of a pipe typically not larger than 100 mm) and data from larger pipes were extremely scarce.

In 2016 and 2019, extensive experimental campaigns were conducted in the GIW Hydraulic Laboratory (Grovetown, GA, U.S.A.) testing flows of Newtonian settling slurries in pipes of 3 very different sizes (103 mm, 203 mm, and 489 mm). We exploit the experimental data to evaluate the pipe-size scale-up ability of the heterogeneous V₅₀-model and the stratified V_sm-model. The evaluation includes an analysis of the pipe-size effect on the characteristic velocities of the models: the suspension velocity V₅₀ and the deposition-limit velocity V_sm.

Industrial slurries transported in pressurized pipelines often consist of particles of broad size distribution. The broad particle size distribution affects slurry flow behavior in a pipe. A four-component model (4CM) predicts the frictional pressure drop in pipe flow of broadly graded slurry. The model considers Newtonian carrying liquid and splits the broadly graded solids into fractions (components) each of which contributes to the pressure drop through its own dominating friction mechanism expressed by a particular sub-model in the 4CM. The sorting of the solids into the components (carrier, pseudo-homogeneous, heterogeneous, fully-stratified) must be based on appropriate criteria. For the sake of simplicity, the 4CM currently uses threshold sizes of particles to split the solids into 4 components.

The goal of the present work is to analyze the existing criteria for the threshold between the pseudo-homogeneous component and heterogeneous component and for the threshold between the heterogeneous component and fully-stratified component. The analysis is based on a description of mechanisms governing particle support (suspension, deposition) of each particular solids component in slurry flow. It shows that the existing grain-size thresholds actually express certain proportions among threshold velocities of flow delimiting different slurry flow regimes. Such threshold velocities are the deposition-limit velocity, the initial-suspension velocity, and the full-suspension velocity. We discuss the proportions and demonstrate how properties (of liquid, solids, flow) and associated parameters additional to the grain size may influence the thresholds.

The analytical results are supported by experimental results for flow of individual components in a laboratory loop.

Slurries in mineral processing typically have average particles sizes of 20 to 100μm with maximum sizes of up to 500 to 1000μm. With solids volumetric concentrations varying from a few percent up to and over 40% the corresponding slurries are here termed complex because they cover an intermediate area between "non-settling" and "settling" types of mixtures. Depositional and flow resistance behaviours, some of which may be considered counter-intuitive, are discussed based on reported observations with heavy ore concentrates, tailings and sand slurries.

Observations have shown that large quantities of ground heat are lost when air flows through storm water systems during cold spells in winter. The temperature distribution in the ground around a storm water pipeline under a street was examined. The non-linear problem of heat conduction with phase change in moist soil was mathematically modelled and the model was used to simulate ground temperature changes caused by the flow of cold air in a buried pipe. Some consequences of airflow cooling are schematically discussed

Effects of chemical additives and a freeze-thaw cycle on the flow of mainly fine-grained industrial slurries are demonstrated based on experimental results and reported pilot-scale tests. The hydrodynamic behaviour of coarse particle transport at very high concentrations is schematically demonstrated by experimental data and it was concluded that the flow cannot generally be represented by a simple rheological model.

The balance of the costs for capital, energy, maintenance and boundarylayer polymer injection is described in a model for life cycle cost assessmentsof pumping sewage sludges at a solids content (TS) in the range of15 to 35 %. A design tool for sludge pumping with solid contents of up to8 % is also described. Tests with centrifugal pumps for TS-values of up to10 % are presented.

Heat pumps based on the phase change from ice to water require large quantities of ice being transported hydraulically. Some preliminary pipeline transport parameters have been evaluated from pilot-scale experiments. Furthermore, the dynamics of a large spherical ice particle was observed and compared to the governing hydrodynamic equation.

The effectiveness of using hydraulic transportation as a link in integrated systems for mining, processing, and waste handling is to be demonstrated and discussed. Hydraulic transportation often requires additional comminution of particles in the mining area; therefore, the concept of slurry pumping from open-pit or underground mines requires the traditional grouping of mining and concentration operations to be broken up. The feasibility of coarse particle pumping is demonstrated for integrated handling of waste rock and tailings with geotechnically stable co-disposal in one disposal area

In underground mining, a hydraulic hoisting system can increase the hoisting capacity without necessitating the sinking of new shafts. There is generally a considerable inflow of groundwater which has to be pumped out. When the mine dewatering installations are integrated with a hydraulic hoisting system, the cost of power needed to pump out the groundwater is excluded from the costs of hoisting, compared with other modes of transporting the solids to the surface. Different hydraulic systems are analyzed and leading parameters such as total energy consumption and underground water availability, are related systematically to representative solid to water mass ratios and pump efficiencies. The economical effectiveness of integrating the mine dewatering and the hydraulic hoisting system is demonstrated, and finally some schematic layouts of applications are presented

The present study is an experimental investigation of the performance of a rubber-lined centrifugal pump when pumping ores and industrial minerals with concentrations by weight of up to 65-70%. The upper limit of particle size was about 8 mm. The clear water head and efficiency were lowered 30-40% by the coarsest iron ore investigated. Most experimental data were correlated to a formula expressing the influence of solid concentration and solid properties on the reduction in pump head. The drop in efficiency was equivalent to the drop in head up to volumetric concentrations of 20-25%. With higher concentrations the drop in efficiency became greater than the drop in head.

Savings in energy and water can be effected at Swedish ore-dressing plants if tailings slurry can be thickened more effectively. Most of the water could be re-used directly allowing recovery of energy (heat). The potential in Swedish mines is about 50 GWh, and most of the energy savings would replace oil . The water balance, pH, metal content and sulphate ion content at the Garpenberg works are shown. The degree of direct circulation in the complex flotation of sulphide ores is limited by water-quality problems

In the refining of ores large amounts of fine-grained mineral particles (tailings) are generally transported together with water (slurry) in pipelines, sometimes as far as several kilometers to the disposal area.

Great savings of energy and water can be obtained at concentrators if the tailings slurry is thickened more effectively and water is reused directly instead of being transported the long way around the disposal area. With direct circulation in sub-arctic regions, large amounts of heating energy can be recovered using a heat pump arrangement. The potential savings at a Swedish concentrator were estimated to be about 10-20 GWh per year, the majority of which would be savings in oil. Furthermore, handling of mine tailings products at low water content offers environmental benefits, and more effective deposition techniques can be used.

In cold areas, temperature and hydrological conditions greatly influence spreading and dissipation mechanisms of pollutants released in the process. Monthly variations of the discharge to the recipient of a substance emitted in the process were simulated in an example. The degree of direct circulation in flotation of complex sulphide ores may be limited by water quality problems in the process. A mathematical model was developed and used to simulate the accumulation of a substance in the process for different degrees of direct circulation.

Finally, a schematic layout of a simple aeration plant for recycled process water was outlined and some regional water-related problems were discussed.

Design of mine-tailing pipelines and other short-distance applications involves many of the considerations of long-distance pipeline transportation and is often complicated by variation in particle sizes and solid throughput. In this study, a modified tube viscosimeter is used to obtain rheological data for clay, coal, and iron ore slurries. Temperature-dependent changes in the rheological properties are evaluated for some applications in cold regions. A modified tube viscosimeter was constructed in order to eliminate some correction problems with this type of equipment. Rheological data for clay, coal, and iron ore slurries were obtained with both tube and rotational viscosimeters, which means that a large span of shear rates was investigated. Temperature-dependent changes in rheological properties were evaluated for some applications in cold regions. Freezing is an effective means of thickening fine-particled slurries such as clay-water mixtures and sludges. The rheological results with kaolin and coal slurries showed that the flow properties at constant solids concentration were not changed after a freeze-thaw cycle