Slurry Transport Research Articles

Optimization of Transport Performance and Strength of the Filling Slurry in Tailings Reservoir Waste by Adding Air Entraining Agent

At present, many mines adopt the filling method. It is particularly important to solve the problem of the long-distance transportation of slurry during the filling process. Based on the high-density filling material of Sanning mine, the experiments were designed to add sodium abietate (SA), triterpene saponin (SJ) and sodium dodecyl sulfonate (K12) with concentrations of 0.0%, 0.2%, 0.4% and 0.6%, respectively, which were used as air entraining agents (AEA). The filling body with the curing age of 7 and 28 days was prepared for various tests, including nuclear magnetic resonance (NMR), and alternating current (AC) impedance tests. The effects of the air entraining agent and curing time on the physical properties, pore structure and AC impedance properties of the filling were obtained. The results show that: (1) within the frequency range of 10−1–105 Hz, the variation trend of AC impedance of the filling body cannot be changed by adding the air entraining agent, and the filling body with the same ratio had a similar topological structure. (2) The filling body with different AEA and curing times can be represented by the same equivalent circuit model, while the maximum chi-square coefficient was 0.46%. (3) Under the condition of a high frequency of 105 Hz, the porosity and uniaxial compressive strength of the filling body with 7 day curing age were linearly correlated with the AC impedance. However, the porosity and uniaxial compressive strengths of the filling body with 28 days curing time were affected by the type of AEA at a high frequency of 105 Hz.

Research on the fluid characteristics of cemented backfill pipeline transportation of mineral processing tailings

With the deepening of underground resource exploitation, the application of cemented backfill pipeline transportation of mineral tailings has become the best option to reduce the risk of deep ground pressure and solid waste pollution. Research in this field is mainly centred on slurry fluidity experiments. However, the slurry transportation parameters, particle characteristics and complexity of the pipeline all cause uncertainty in the calculation of backfill pipeline transportation parameters. The conventional backfill loop test is expensive. Combining structural fluid tests with particle flow models, this paper presents a method to optimize backfill pipeline transportation parameters. The H-B model is employed to analyse the transportation resistance of backfill slurry along the line to establish the relation function between the resisting force and the parameters. Adoption of a custom function improves the accuracy of the inter-phase drag model and the erosion effect. This paper analyses the flow state of the high-concentration solid-liquid dense phase fluid in backfill gravity transportation to obtain optimized transportation parameters. The research results improve the accuracy of the calculation of the backfill pipeline transportation parameters, which can be effectively applied in the optimal design of high-concentration slurry backfill pipeline transportation.

Promising bending properties of a new as-rolled medium-carbon steel achieved with furnace-cooled bainitic microstructures

The bending properties of a new thermomechanically processed medium-carbon (0.40 wt% C) low-alloy steel, intended for the slurry transportation pipeline application, have been investigated. The studied material was hot-rolled to 10 mm thick strips followed by direct quenching to two different quench-stop temperatures (QST) of 560 °C and 420 °C. The samples were subsequently cooled slowly to room temperature in a furnace, producing two different bainitic microstructures. In general, the final microstructures on the centerline consisted of different bainitic features with yield strengths of a ~700 MPa and ~1200 MPa for QST 560 °C and 420 °C, respectively. To determine the factors affecting bendability, as determined by three-point brake press bending tests, local microstructural features and texture were characterized with transmission and scanning electron-microscoy and macrohardness tests. Detailed quantitative microstructural evaluation of both subsurface and mid-thickness regions revealed that the bainitic sample produced at the higher temperature (QST 560) consisted of almost equal amounts of bainite types B1 and B2, where B1 has bainitic sheaves with a low dislocation density and intralath cementite, and B2 a very dislocation-dense morphology with mainly interlath cementite. In the QST 420 sample, the high dislocation density components B2 bainite and martensite were dominant, although martensite was only present near the strip surfaces. Different post-rolling cooling conditions did not change the general crystallographic theme but resulted in a slight increase in the texture intensity of the QST 420 sample. Neither the concave nor convex subsurface regions showed significant changes in texture after bending. The more favorable distributions of microstructural components and textural component intensities in the QST 560 sample resulted in higher elongation to fracture and work-hardening capacity, resulting a smaller minimum usable punch radius than for the stronger QST 420 sample. Fractographic examination of the cracked surfaces revealed that cracks developed by shear band formation followed by surface roughening, which promoted subsequent void and micro crack nucleation and growth.

Advanced comminution modelling: Part 2 - Mills

This second part paper explores rock breakage mechanisms, the life cycle of rocks in mills and the strong influence of end walls on charge motion within mills. We present recent advances in particle-based modelling of mills for comminution focused around wear and the effect of slurry and slurry phase grinding. Three mill scenarios are considered:1.Media flow and the resulting wear evolution of the belly and end wall liners and the resulting change in mill performance for a full industrial scale dry ball mill (modelled using DEM)2.Axial slurry transport and mixing in a wet overflow industrial scale ball mill (modelled using fully coupled DEM and SPH)3.Effect of mill speed on slurry and solid charge motion and the resulting grinding of fine particles in a 1.8 m diameter wet Hardinge pilot mill (modelled using fully coupled DEM and SPH with advection-diffusion-population balance equations solved for the slurry size distribution for each SPH particle)These demonstrate the nature and level of fidelity that is now possible to include in particle-scale comminution models. They provide insights into the critical importance of curtain flows generated by the end walls of tumbling mills, on wear behaviour on liners, on the structure of slurry pools and mill discharge and on the adverse effect on grinding of increasing mill speed.

Rapid Wear Modelling in a Slurry Pump Using Soft 3D Impeller Material

Slurry transport systems are often limited in run length by the life of the pump internals, especially the impeller. The present work investigated abrasive wear of the impeller of a Hayward Gordon XR2(7) Torus Recessed Impeller slurry pump in a flow loop. The stock stainless steel impeller was replaced by a set of plastic test impellers with the same nominal geometry, fabricated by additive manufacturing (3D printing). A parametric set of abrasive wear experiments was conducted at five pump rotational speeds and three solid concentrations of garnet slurry in a pipe flow loop. Pump performance tests were conducted using impellers with progressive wear conditions, to investigate how a worn impeller affects hydraulic power delivery. A parabolic fit was imposed to describe the relationship between head and flow rate, and an empirical model was proposed to predict the pump head with damaged impellers. When the rotational speed is high, the damaged impeller has a larger effect on the pump’s performance than when the rotational speed is low. The head difference between the undamaged impeller and a 7.62%-mass-loss damaged impeller was 1.5 m at 1750 rpm rotational speed, however, for 850 rpm, the head difference was 1 m. Implications for pump diagnostics in other types of systems are discussed. This experiment gives a method for rapidly assessing wear locations, and provides a tool to predict wear rates on harder materials if scaling parameters are available. This first attempt at a scaling law is not reliable enough to accurately predict the wear rate for specific conditions, but shows the relative wear as a function of pertinent parameters.

Numerical simulation and comparative analysis of pressure drop estimation in horizontal and vertical slurry pipeline

Transportation of solids with water as a carrier in the form of slurry through long length pipelines is widely used by many industries and power plants. The transportation of slurry through vertical pipeline is a challenging task and require modification to overcome the pressure loss and power consumption requirements. In this perspective, numerical simulation of three-dimensional horizontal slurry pipeline (HSPL) and vertical slurry pipeline (VSPL) carrying glass beads solid particulates of spherical diameter 440 µm and density 2,470 kg/m3 is carried out. The 3D computational model for horizontal and vertical slurry pipeline is developed for a pipe of 0.0549 m diameter and analyzed in available commercial software ANSYS Fluent 16. The simulation is conducted by using Eulerian multiphase model with RNG k-ɛ turbulence closure at solid concentration range 10 – 20% (by volume) for mean flow velocities ranging from 1-4 ms-1. It is found that the pressure drop rises for both HSPL and VSPL with escalation in mean flow velocity and solid concentration. The predicted pressure drop in VSPL is found to follow the same pattern as with HSPL but higher in magnitude for all chosen velocity and solid concentration range. The obtained results of predicted pressure drop in HSPL are validated with the available experimental data in the literature. A parametric study is conducted with the aim of visualizing and understanding the slurry flow behavior in HSPL and VSPL. Finally, the results of solid concentration contour, velocity contour, solid concentration profiles, velocity profiles and pressure drop are predicted for both the slurry pipelines.

Effect of fracture roughness on the hydrodynamics of proppant transport in hydraulic fractures

The effect of fracture roughness is investigated on proppant transport in hydraulic fractures using Joint Roughness Coefficient and a three-dimensional multiphase modelling approach. The equations governing the proppant transport physics in the fracturing fluid is solved using the hybrid computational fluid dynamics model. The reported proppant transport models in the literature are limited to the assumption of a smooth fracture domain with no fluid leak-off or fluid flow from fracture to rock matrix interface. In this paper, a proppant transport model is proposed that accounts for the proppant distribution in rough fracture geometry with fluid leak-off effect to surrounding porous rock. The hydrodynamic and mechanical behaviour of proppant transport was found directly related to the fracture roughness and flow regime especially under the influence of low viscosity fracturing fluid typically used in shale gas reservoirs. For the proppant transport in smooth fractures, the fracture walls employ mechanical retardation effects and reduce the proppant horizontal velocity resulting in more significant proppant deposition. On the contrary, for the proppant transport in rough fractures, the inter-proppant and proppant wall interactions become dominant that adds turbulence to the flow. It results in mechanical interaction flow effects becoming dominant and consequently higher proppants suspended in the slurry and greater horizontal transport velocity. Furthermore, the mechanical interaction flow effects were found to be principally dependant on the proppant transport regime and become significant at higher proppant Reynolds number.

Numerical Assessment of Shear Boundary Layer Formation in Sewer Systems with Fluid-Sediment Phases

Numerical and empirical studies of soil slurry transport and deposition in urban stormwater sewers are few, presumably due to the difficulty of direct observation of soil slurry flow in stormwater pipes. Slurry in a sewer system includes both suspended load and bedload, but few studies have attempted to demarcate these two components. A boundary layer is a crucial determinant of sediment transport capacity. Stormwater runoff enters the sewer in turbulent flow, mostly mixed with soil slurry generated by rainfall. In this paper, we attempt analysis using ANSYS Fluent commercial CFD software. We describe the development of a numerical analytical methodology capable of predicting the flow of soil slurry in stormwater pipes, and propose a method for estimating the sediment–flow boundary layer. Using this model, we simulated stormwater runoff with a large content of soil slurry during a rainfall event. We investigated soil slurry transport and predict the formation of shear boundary layer by varying the inlet conditions (volume of soil slurry entering the stormwater sewer system) and by analyzing the flow velocity field and soil slurry volume fraction in the pipes under various experimental flow conditions. Based on the shear and settling velocity of sediment particles, we propose criteria for the formation of a shear boundary layer in stormwater pipes.

Effect of Rock Abrasiveness on Wear of Shield Tunnelling in Bukit Timah Granite

The abrasiveness of rocks significantly influences the wear endured by excavation tools in tunnel boring machines (TBMs). In slurry shield TBMs, wear occurs not only in excavation tools but also in discharge pipes and pumps of slurry transport systems. To explore this phenomenon, this study investigated the effect of rock abrasiveness on the wear of both disc cutters and slurry discharge pipes in slurry shield TBMs. The radial wear of disc cutters and the thickness of slurry discharge pipes were measured and monitored at a TBM site in Singapore. The relationship between the weathering grade of Bukit Timah granite and the wear coefficient of disc cutters was analysed, and a correlation between the Cerchar Abrasivity Index values and the wear coefficient of 19 inch disc cutters was suggested. Additionally, the average wear rates of slurry discharge pipes used for Bukit Timah granite were determined based on the pipe thickness measurements. The wear rates of weathering grades G(I) to G(IV) of Bukit Timah granite were observed to be highly similar to each other, whereas the wear rates of G(V) grade and mixed ground were 1.55 times higher than those of the G(I) to G(IV) grades. The correlation between the slurry discharge velocity and the wear rate in slurry discharge pipes was thus derived. The accurate assessment of the effect of rock abrasiveness on both the wear of disc cutters and the wear rate in slurry discharge pipes, investigated in this paper, will highlight the need for efficient maintenance of the excavation tools in TBMs and encourage the development of various equipment wear prevention measures in order to minimize overall construction costs and time.

Slurry Pipeline for Fluid Transients in Pressurized Conduits

Morocco is known by the pipeline from Khouribga to Jorf Lasfar that is considered as one of the most world’s largest for the slurry transportation. This phosphate slurry undergoes different manufacturing process. During this process, the rheological properties of the slurry have been taken into account, and next adapted for our study. There are numerous approaches in the literature which investigate different Eulerian-Lagrangian, Eulerian-Eulerian and Stochastic models to simulte the slurry flow [1], [2]-[3]. Actually, it is very difficult to consider all variables for establishing a general model, we build an Eulerian and a homogeneous one in easier framework. Among these variables, there is the stress tensor which is involved in the model. Since it is considered null, then the non-Newtonian fluid is approched by multiple friction factors. In the present work, a onedimensional three-fluid model is developed in Python. The physical model features a mass and momentum balance for each fluid. It allows to predict the pressure drop and flow patterns. The hydraulic transport of slurry system in horizontal tubes has been investigated. To simulate it dynamically, continuity and momentum equations used in applied engineering problem, are solved together. These equations are conveniently solved using the method of characteristics (MOC). The reason for utilizing this method is the robustness and efficiency compared to the finite volume method (FVM). The originality for this work takes into account the physical discontinuity at interface separating slurry and water which mix with each other. The numerical results from the numerical code model head and pressure losses. We test numerically the fitting of the model with the real physical problem. Then the model is used on simplified examples in order to show its capability to be used to predict the flow behaviour in different regimes, showing consequently its consistency.

EFFECTIVE PARAMETERS OF TAIL PROCESSING GOLD-BEARING ORE HYDROTRANSPORT FOR VERNINSKAYA PROCESSING FACTORY

The paper shows that in order to increase the efficiency of hydraulic transport systems in mining the transportation of slurries with a high concentration of solids in the slurry flow. Experimental studies have shown that slurry tailings of gold-containing ore with mass concentration of more than 55% are viscoplastic fluids. Experiments on a rotational viscometer allowed us to establish the main rheological characteristics of the studied slurries. Experimental studies of hydraulic transport performed on a laboratory setup, confirmed the results obtained on a rotational viscometer. Curved mixture streams are inclined straight lines that cut off on the axis of the head the sections, which determine the initial hydraulic slope corresponding to the shear stress yield on the rheological curves. According to the results of the experiments, a method has been developed for calculating the hydraulic transport of highly concentrated slurries of tailings of gold-bearing ore. Head loss values increase with increasing concentration. A sharp increase in head loss occurs in the concentration range from 60 to 65% and above

Magnetic peristaltic pumps for stowing operations

Relevance of the work. The use of laying the workings is intended to increase the safety of mining operations, namely, controlling mining pressure, reduce mineral loss during excavation, prevent the occurrence of underground fires, and reduce the risks of destruction of objects in residential areas. Methodology of the work. The article is devoted to the study of the possibility of applying the system of peristaltic transportation of pasty slurries using the energy of a traveling magnetic field to work on the laying of the goaf. Taking into account the features of the materials used as the basis for filling mixtures, the specifics of the process of moving the latter to the place of laying, innovative technologies for transporting filling mixtures are becoming increasingly important. Results and scope. A fundamentally new approach to the transportation of liquid and viscous media is the use of low-frequency magnetic peristaltic pumps. The design of this pump involves the use as an executive body of the working channel, made of a magneto-active elastomer. By its extension under the influence of a traveling magnetic, periodic waves of local deformation pass, moving the filling mixture. Conclusions. The rejection of the traditional roller system, which presses the channel, and the replacement of the main executive body of the pump with the working channel, the structuring flow and preventing its separation, will expand the scope of application of pumping equipment during filling operations. The pressure developed by the pump depends on the energy characteristics of the traveling magnetic field. Studies have shown that the speed of movement of a wave of local deformation when moving various materials is sufficiently stable and slightly depends on the viscosity of a substance.

Effective Parameters of Tail Processing of Gold-Bearing Ore Hydrotransport for Verninskaya Processing Factory

The article is devoted to the analysis of the composition and properties of the materials and liquids during transportation using pipeline and shows that in order to increase the efficiency of hydraulic transport systems in mining a transition to the transportation of slurries with a high concentration of solids in the slurry flow is necessary. Experimental studies have shown that slurry tailings of gold-containing ore with mass concentrations of more than 55 % are viscoplastic fluids. Experiments on a rotational viscometer allowed us to establish the main rheological characteristics of the studied slurries – shear stress and the dynamic effective viscosity. It has been established that over the entire range of concentrations from 55 to 65 %, the flow of slurries is described by the Bingham rheological equation. Experimental studies of hydraulic transport performed on a laboratory setup with a pipeline diameter of 50 mm confirmed the results obtained on a rotational viscometer. The curved of mixture stream is inclined straight lines that are cut off on the axis of the head in the sections, which determine the initial hydraulic slope corresponding to the yield shear stress on the rheological curves. According to the results of the experiments, a method has been developed for calculating the hydraulic transport of high concentrated slurries of tailings of gold-bearing ore. Calculations showed that in a given range the performance of the hydrotransport system and the mass concentration of the solid phase pressure losses vary from 11 to 84 m of water column/m. Head loss values increase with the increasing concentration. A sharp increase in the head loss occurs in the concentration range from 60 to 65 % and higher.

Numerical Investigation on Critical Velocity of Ice Slurry Flow

The use of ice slurry as a working fluid in secondary-loop of refrigeration system not only enhances the system performance but also reduces the refrigerant charge and its leakage to environment. It can be transported through pipes; however, flow of ice slurry is a quite complex two phase flow, which significantly differs from conventional fluid flow. Ice slurry flow can be influenced by on several operating parameter viz. initial velocity, ice concentration, freezing point depressant concentration and particle size. Solution of such type of flow through pipe is a difficult task through experiments due to complexities in visualization and measurements. Therefore, a CFD model is developed to simulate the ice slurry flow to predict the safe conditions for the transportation of ice slurry. In the present work, numerical investigation of flow of ice slurry has been analyzed in order to predict the critical velocity and effect of different parameters on critical velocity. Eulerian granular flow model has been used for the simulation, which is also validated with existing experimental results in the literature. Result shows that, the critical velocity is especially influenced by the particle size. Critical velocity at 10 % initial ice concentration increases from 0.4 m/s to 0.16 m/s with increase in particle size from 0.1 mm to 0.4 mm.

Odour Assessment for a Pig Farm Through Dynamic Olfactometry and Air Dispersion Modelling in Order to Reduce the Odour Pollution Using Biotechnologies

Odour represents one the most actual topics in terms of industrial pig farming pollution effects, mainly because of the increasing number of settlements build in traditional farming areas but also because of the overpopulation of pigsties. The odour impact assessment was requested by a big pig farm in order to comply to the request of the Environmental Agency to reduce the odour impact on nearby settlements. Odour assessment was done using dynamic olfactometry, mathematical modelling of dispersion and FIDOL factors. The initial assessment was used to elaborate and apply an odour management plan based on biotechnologies which consisted mainly in biological treatments applied to the floor of the pigsties, the slurry transportation channels and the slurry tanks with specific products designed to reduce the Ammonia level, break down her sulphurous compounds in the slurry and increase the quality of the slurry as fertilizer, with the final target of reducing the odour emissions. Results indicate a considerable decrease of odour concentrations in the closest settlements, around the farm and inside pigsties. Further measures must be taken as the concentrations are still over the limit values from most European countries.

Role of rheology on the hydraulic transportation of lignite coal and coal ash slurries in the pipeline

ABSTRACT The transportation of Lignite coal and Coal ash in slurry form through pipelines is economically and environmentally more viable than the other conventional modes of transportation. The main focus of the present work is to demonstrate the effect of particle concentration and size on the rheological properties of slurries and to further investigate the head loss, energy consumption, energy cost, and transport capacity during slurry transport through pipes. The rheology data indicate the shear thinning flow behavior for all particle concentrations and sizes examined in the shear rate () range of 10–500 s−1. The high viscosity of slurry containing fine particles can be reduced by introducing an optimum concentration of coarse particles, which subsequently results in lower head loss, energy consumption, and cost. A Power-law model is fitted to rheological flow curves in order to obtain flow behavior index (n) and consistency coefficient (k), which are then used to calculate specific energy consumption and head loss. The energy cost in USD per ton per 100 km is calculated from the specific energy consumption and is found to be substantially cheaper than the existing rail and road transportation costs in India.

The application of the yield approach to study slurry migration in drill cuttings waste underground disposal

The underground disposal of drill cuttings waste is a common practice for the gas/oil industry to achieve zero-discharge sustainable development. In this study, a numerical modeling approach was developed to simulate the slurry flow for underground disposal of drill cuttings waste. The modeling approach was coupled with and implemented in the well-known general purpose subsurface multiphase flow simulator, TOUGH2. The new modeling approach treats the slurry flow behavior in subsurface systems as Bingham plastic liquid, with a linear relationship representing the yield stress and the concentration of the gelatinizer in the slurry. In addition, the precipitation-dissolution process was taken into account for solid-aqueous phase changes of the water-slurry mixture under and over the threshold pressure. The model has been verified by the analytical solution of a transient flow of single-phase Bingham fluid, and has further been tested by modeling field-scale injection of drill cutting wastes into a multi-layered geological formation in Texas. A hypothetical model has also been used to conduct sensitivity analysis of the impact of slurry density, injection depth and injection pattern on the storage formation performance. The results revealed that the effect of injection volume is greater than the mass on pressure buildup. In addition, a short period of intermittent reinjection can lead to an earlier formation breakdown due to particle sedimentation and reduce the storage capacity. The developed model can be used to evaluate the prediction of slurry transport, storage capacity, pressure distribution, and the formation breakdown time in a drill cuttings waste disposal project.

Investigation of the Impact of Pad Surface Texture from Different Pad Conditioners on the CMP Performance

Chemical mechanical polishing (CMP) is a common method for planarization/polishing materials during integrated circuits (IC) fabrication. Pad conditioning is a critical component of a CMP process. Herein, the impact of surface textures created by different types of pad conditioners (PC) such as coarse, mid-coarse, and fine PC on the solid pads are studied. Additional surface texture parameters such as surface height distribution, skewness, Dale Void Volume are used to determine an optimum surface texture that gives desired CMP performance such as material removal rate and within-wafer non-uniformity. It was determined that an optimum surface texture on a solid CMP pad can be obtained with a mid-coarse disk. It is further demonstrated that by the addition of porosity to the pads, it is possible to recreate an optimum surface texture and desired CMP performance, similar to that obtained with a mid-coarse disk and a solid pad. Tribological mechanisms of the different pad and PC combinations are presented using the coefficient of friction. It is concluded that porous pad and fine PC pairing can tackle the issues of slurry transport limitations, lack of asperity contact, and process stability over pad life.

Recent advances on stabilization and rheological behaviour of iron ore slurry for economic pipeline transportation

Slurry transportation through pipelines is an environment friendly method. So, this alternative mode of transportation of raw materials through pipelines in the form of slurry will go a long way in reducing the problems of congested transportation network. The stable slurry is pumped over a long distance where the further processing may be carried out. Surface active agents (also called surfactants) are a class of compounds having both polar and non polar groups on the same moiety. On being adsorbed to minerals, they change the surface characteristics by affecting the interfacial behaviour of minerals. The viscosity, flotation, dispersion, wetting properties of minerals can be monitored with the proper selection of chemical additives. The stability and rheological behaviour of OWS has great indication towards the process of transportation. In this work, we have reported the stabilization of various types of slurries (particularly iron ore slurry) with their rheological behaviour and CFD analysis for economic pipeline transportation.

Resistance mechanisms and resistance reduction of slurry in pipeline

Resistance of slurry in pipeline is an important parameter in designing a slurry-conveying pipeline, which affects the cost of transportation of slurry. Therefore, it is of importance to study the resistance mechanisms, and to adopt proper technologies in reducing the resistance of slurry in pipeline. Resistance mechanisms of both fully stratified flow and fully suspended flow were discussed on the basis of analyzing the flow state of slurry in pipeline home and abroad. Technologies of reducing the resistance by adjustingthe sizes of particles, adding resistance reducer and rising temperaturewere summarized considering the influencing factors on resistance of slurry in pipelines.