Slurry Parameters Research Articles

A novel slurry for atomic-scale polishing of KDP crystals

Abstract Atomic-scale surfaces and structures have been playing a significant role in the next generation of devices and products. Potassium dihydrogen phosphate (KDP) crystals are crucial in energy sectors but challenging for ultra-precision processing due to deliquescence, brittleness, and low hardness. This paper introduces a novel chemo-mechanical slurry designed for achieving atomic-scale polishing of KDP crystals. The slurry employs a combination of polyethylene glycol (PEG) and anhydrous ethanol (AE) to counter deliquescence. In addition, graphite oxide (GO) with KOH is incorporated to prevent the embedding of SiO2 abrasives and the dissolution of KDP in deionized water (DW). The mechanism underlying the formation of an ultra-smooth surface is elucidated based on the analysis of the X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM) test. Response surface method (RSM) is used to optimize the slurry parameters and finally obtaining an atomic-scale surface with Sa 0.3 nm.

Three-Dimensional-Printed Composite Structures: The Effect of LSCF Slurry Solid Loading, Binder, and Direct-Write Process Parameters.

In this research, a direct-write 3D-printing method was utilized for the fabrication of inter-digitized solid oxide fuel cells (SOFCs) using ceramic materials. The cathode electrode was fabricated using the LSCF (La0.6Sr0.2Fe0.8Co0.2O3-δ) slurry loading and the Polyvinyl butyral (PVB) binder. The rheological parameters of slurries with varying LSCF slurry loading and PVB binder concentration were evaluated to determine their effect on the cathode trace performance in terms of microstructure, size, and resistance. Additionally, the dimensional shrinkage of LSCF lines after sintering was investigated to realize their influence on cathode line width and height. Moreover, the effect of the direct-write process parameters such as pressure, distance between the nozzle and substrate, and speed on the cathode line dimensions and resistance was evaluated. LSCF slurry with 50% solid loading, 12% binder, and 0.2% dispersant concentration was determined to be the optimal value for the fabrication of SOFCs using the direct-write method. The direct-write process parameters, in addition to the binder and LSCF slurry concentration ratios, had a considerable impact on the microstructure of cathode lines. Based on ANOVA findings, pressure and distance had significant effects on the cathode electrode resistance. An increase in the distance between the nozzle and substrate, speed, or extrusion pressure of the direct writing process increased the resistance of the cathode lines. These findings add to the ongoing effort to refine SOFC fabrication techniques, opening the avenues for advanced performance and efficiency of SOFCs in energy applications.

Research progress on hydraulic performance prediction method for large dredge pumps

Abstract The dredge pump is the core equipment in a dredger, which is used to transport dense dredged soil excavated by the dredger. However, the slurry performance of a dredge pump is usually calculated via empirical formula based on the clean-water performance data obtained by numerical simulation or model test, and the conversion accuracy is difficult to evaluate. This paper focuses on reviewing the present technologies of slurry performance test as well as numerical simulation for centrifugal solid-liquid pump. Research progress on special instruments required for testing slurry parameters as well as numerical models for simulating dense solid-liquid flows was summarized. An example was presented to illustrate the scale effect and possible error source in performance conversion between model and prototype pump and then technical difficulties and future research directions in hydraulic performance prediction for dredge pump were put forward.

Dynamic characterization of water hammer in gangue fly ash slurry pipelines during valve closure

In the process of coal-filling mining, the gangue fly-ash slurry (GFS) needs to be transported over a long distance to reach the gobs. The abrupt closure of the valve during the transportation of GFS can result in a water hammer that significantly endangers the stability and safety of the pipeline transport system. To study the fluctuations in pressure induced by abrupt closure of the valve, experiments on the rheological parameters of gangue-coal ash slurry were conducted. Transient numerical simulations were carried out using the computational fluid dynamics method for various valve closing times. The results indicate that, with the increase of slurry concentration, the yield stress of the slurry significantly increases. When the concentration exceeds 76%, the increase in yield stress reaches 38.4% and 35.1%, respectively. Upon valve closure, the internal pressure of the slurry in the pipeline exhibits periodic dynamic oscillations. As the duration of valve closure increases, the frequency of periodic water hammer events decreases. The maximum water hammer pressure caused by valve closure decreases with the increasing distance between the valve and the closure point. At the same time, the intensity of maximum water hammer pressure fluctuations increases with the increase in slurry concentration and flow velocity in the pipeline. The results can provide references for water hammer protection and pipeline selection during the transportation of backfill slurry in mining.

Theoretical model and parameter sensitivity analysis of the filter cake formation during slurry shield tunnelling

The filter cake formation during slurry shield tunneling in high permeability soil layers is complex and difficult to monitor. There is no reliable method to evaluate the mechanical characteristics during the filter cake formation. A theoretical model is proposed to describe the filter cake formation and development in this study. The finite difference method is used to simulate the whole filter cake formation process. In addition, the influence of the key bentonite slurry parameters and of the deep infiltration on the filter cake formation is investigated based on the proposed model. The results show that the excess pore water pressure within the filter cake is not uniformly distributed. The slurry support effect is manifested by a pressure drop generated on both sides of the filter cake. The development process of the filter cake can be summarized into three stages: prior infiltration filling of the filter cake, accumulation and thickening of the new filter cake, and compression and consolidation of the prior filter cake. The slurry deep infiltration results reflected by the membrane specific resistance have the most significant effect on the filter cake development. Compared with the slurry concentration, the viscosity has a greater influence on the formation and final thickness of the filter cake.

Environmental Monitoring of Pig Slurry Ponds Using Geochemical and Geoelectrical Techniques

The efficient management of slurry, which is a by-product rich in nutrients derived from feces, urine, cleaning water, and animal waste that stands out for its high concentration of nutrients such as nitrogen, phosphorus, and potassium, is of vital importance, highlighting the importance of slurry management in storage ponds, which. The Murcia–Spain region has an important number of pig farms. Hence, infrastructures dedicated to managing by-products are necessary to prevent environmental pollution and eutrophication of groundwater. The aim of a recent study was to evaluate the relationship between electrical values and geochemical parameters of pig slurry stored in a pond using ERT and geochemical analysis. In addition, the study was designed to monitor the pond to determine the geochemical characteristics of the slurry and to assess the risk of lateral contamination. The study results indicate a noticeable decrease in electrical resistivity values at 0.4 and 1.6 m depth in surveys 1 and 2. The reduction ranges from 50 to 100 percent. This paper presents a new method for monitoring slurry ponds using electrical resistivity tomography. This non-invasive method provides detailed information on the distribution and characteristics of the fluids, as well as a clear picture of the electrical resistivity of the subsurface.

Investigation on the penetrability of cement slurries with three solid-phase particle sizes in coral sands with different gradations

The law of penetrability of cement slurry in coral sand media is a key issue in the design of foundation grout reinforcement and construction in coral sand formations. Indoor infiltration grouting tests were conducted to evaluate the influences of the characteristic parameters of cement slurry and coral sands on the penetrability, to classify the penetrability of three kinds of cement slurries with different solid-phase particle sizes (SP) in coral sands with different gradations, to ascertain the dominant permeation intervals of typical cement slurries in coral sands in terms of penetrability, and to reveal the dynamic competitive relationships between the SP and viscosity of the slurries on the penetrability. In addition, the influences of the filtration effect on the penetrability in terms of the infiltration channels and the diffusion rate of the slurries were determined. The results showed that the characteristic parameters of the slurry and coral sands affected the penetrability in descending order thus: water-cement ratio, permeability coefficient of coral sands (PC), grouting pressure, and cement particle diameter d90. The ranking of the three typical cement slurry grouting capacity is different according to the different permeation properties of the injected medium. In actual grouting operations, the trade-off between the solid particle size and viscosity of the slurry should be considered based on the permeation performance of coral sands, and a slurry with an advantage of penetrability is selected.

Numerical analysis and experimental study on slurry diffusion characteristics of vortical oscillatory grouting technology considering soil interface

Based on the fluidic jet theory, this study proposes an effective vortical oscillatory grouting technology. The fluid switching mechanism and pressure pulse characteristics are investigated through numerical simulation and experiment. The slurry diffusion performance of oscillatory grouting is compared with that of steady-pressure grouting under various soil parameters and slurry parameters. The effects of soil interface on diffusion behavior are also studied. The results show that the growth and dissipation of the vortex within the tool generate periodic oscillatory fluid, which further produces pressure pulses. During oscillatory grouting, the pressure recovery process inside the fluidic oscillator reduces the pressure of the soil. With the increase in porosity and particle size, the pressure of the soil grouted by oscillatory pressure is noticeably reduced. Despite the lower pressure of the soil, oscillatory grouting demonstrates better diffusion performance, owing to the dynamic flow field and pressure fluctuation. The performance of oscillatory grouting is also influenced by the oscillatory frequency and pressure pulse amplitude. When the soil interfaces are taken into consideration, different fluid domains exhibit complex slurry diffusion patterns. It is observed that the interface that is perpendicular to the grouting direction has a greater influence on grouting behavior. The oscillatory grouting diffusion behavior is more sensitive to the soil interface. This study is expected to improve grouting efficiency and promote the development of new grouting technology.

Field study on pile side grouting reinforcement for in-service pile foundation using segmental localized grouting

Grouting is an effective method to enhance the bearing capacity of in-service pile foundations. The effect of optimizing grouting parameters for in-service pile foundation grouting reinforcement was verified through static load tests. The field tests of the pileless stratum show that the cement-sodium silicate slurry is more favourable for increasing the grouting pressure and more convenient to control the slurry diffusion than cement slurry. The grouting parameters of cement-sodium silicate slurry were determined according to the maximum grouting pressure and quantity. The slurry grouting parameters were cement slurry 1.6g/cm3 and cement slurry to sodium silicate ratio 2.29:1. Moreover, the effective range of segmental localized grouting reinforcement was detected by the resistivity method and in-situ standard penetration test, and the grouting position should be less than 2m from the side of the in-service pile foundation. Finally, it is found that pile side grouting can improve the bearing capacity of in-service pile foundation by 98% through static load test. The research results have reference value and guiding significance for the design and effect detection of pile foundation grouting reinforcement.

Tandem Semiconductor Microwire Slurries for Solar Hydrogen Generation

Meeting the industry goal of $2/kg for solar H2 is a daunting task that will require novel, highly efficient systems which eliminate many of the components and balance-of-systems costs inherent with photovoltaics + electrolyzers. Technoeconomic models have consistently shown that a photoactive slurry reactor for water-splitting could offer the cheapest route to storing solar energy as hydrogen fuel. However, abundant challenges with this approach have thus far limited such particle-based reactors to prohibitively low efficiencies. This talk will highlight our progress toward the development of a tandem semiconductor particle system designed to address the weaknesses of slurry reactors and achieve a high solar-to-hydrogen (STH) efficiency for particle systems. A proof-of-concept tandem structure uses silicon microwires as the base of the particle, with a wider bandgap TiO2 layer grown on top to gain the additional photovoltage necessary to split water. Semiconductor architecture development and performance will be discussed along with early modeling efforts. In-situ magnetic alignment of the particles has been demonstrated for possible improved tandem light management. In addition, slurry optical characterization and photoelectrochemical performance will be discussed as a function of slurry parameters including bubble flowrate, particle concentration, spectral conditions, and light management strategies. Slurry conditions for minimizing back reactions will be discussed as well.

Study on Rheological Properties and Pouring Process of Hydroxyl-Terminated Polybutadiene (HTPB) Propellants.

The process of solid propellant production, which is the most widely used high-energy material, has garnered significant attention from researchers. However, there have been relatively few studies on its processing, due to the unique nature of the casting process. This paper aims to further analyze the pouring process of the propellant slurry. Initially, we obtained a sample of the propellant slurry and measured its rheological parameters using a rotary rheometer. From the analysis of the experimental results, we derived the viscosity parameters and the yield values of the propellant slurry. Subsequently, we simulated the pouring process, setting the slurry parameters based on the data obtained from the rheological measurement experiment. The simulation results demonstrated that the flower plate significantly impacts upon the cutting and separating effect on the slurry during pouring. Upon leaving the flower plate, the slurry descends onto the core mold platform under the influence of gravity, gradually flowing along the edge of the core mold. Although there may be some small voids in the pouring process, the voids will disappear completely at the end of pouring. A comparison with the actual pouring situation revealed a higher consistency between the simulation results and reality, thus establishing the reliability of the simulation method as a reference for analyzing the pouring process.

Rheological properties of CEMI type microfine cement slurry with different fineness

In geotechnical engineering, rheological properties of CEMI type microfine cement slurries are deficient. In this paper, rheological performance of microfine cementitious slurry is studied systematically under five particle fineness, five water-binder ratios (W/B), and different contents of superplasticizers (SP) (naphthalene-based (N) and polycarboxylate-based (PCE)). Rheological performance included rheological behavior (fluidity and flow time), key parameters (yield stress, plastic viscosity, and hysteresis area), and time dependent viscosity. Their correlations and reasons were discussed. The results showed that rheological parameters did not change significantly when the W/B is greater than 1.5. For MCIV slurry without SP, when the W/B increased from 1.5 to 2.0, yield stress decreased from 2.3 to 1.53 Pa, plastic viscosity decreased from 8 to 4.5 mPa·s, and hysteretic area is reduced from 466.6 to 206.8 Pa/s. The W/B affects rheological parameters significantly compared with the fineness. The critical rheological model transformation condition of MCII slurry was determined when W/B was 1.2 without SP. For MCIII and MCIV grouts with W/B of 1.0, rheological parameters of slurries with 0.3% PCE are close to those with 0.7 % N. Quantitative relationships among rheological parameters and behavior were established, and correlations were determined. Moreover, relationships among apparent viscosity and W/B, fineness and time are established. To ensure grouting effectiveness in applications, a combination of W/B of 1.0–1.5, MCIII or MCIV fineness, 0.3–0.4% PCE or 0.5–0.7 % N is suggested.

Experimental study on time-dependent rheological properties and mechanical performance of cemented fine tailings backfill mixed with polypropylene fiber.

By preparing fine tailings slurry with different mass concentration and fiber content, the rheological parameters of slurry with different fiber content and curing time were tested. In addition, the influence law of fiber content and curing time on compressive strength was analyzed through the prepared fine tailings backfill samples, and the microstructure characteristics of fine tailings backfill were further studied. The results show that when the fiber content is 0.2 ~ 1.2%, the yield stress and plastic viscosity of the slurry increase with the increase of fiber content, and the thixotropy of the slurry also shows the same change characteristics. The bridge effect of fiber makes it easier for forming network structure, which increase the slurry rheology. When the curing time ranges from 0h to 2.5h, the increasing of curing time leads to the increasing trend of rheological parameters, and also increases the thixotropy of slurry. However, the increase of rheological parameters will continuously decrease when the curing time exceeds 1h, indicating that the influence of curing time on yield stress and thixotropy will gradually weaken with the continuous extension of curing time. When the curing age increases from 3 to 56days, the compressive strength of the fine tailings backfill increases with the curing age, but the increasing range of compressive strength decreases gradually. When the fiber content ranges from 0.2 to 1.2%, the compressive strength of backfill increases first and then decreases with the increase of fiber content, and reaches the maximum value when the fiber content is 0.6%. The extension of curing time reduces the generation of large-scale pore structure, which promotes the formation of more compact microstructure of backfill.

Diffusion law of coal gangue slurry and the application of fluidized filling technology of gangue in caving area

In order to deeply study the basic characteristics, diffusion laws, and flow laws of coal gangue and coal gangue slurry, the basic characteristic parameters of coal gangue and coal gangue slurry were obtained through particle size distribution test, electron microscope scanning test, X-ray diffraction test, X-ray fluorescence spectrum test, and angle of repose test. The conveying performance test of coal gangue slurry was carried out, and based on this, a simulation test of coal gangue slurry caving areas was designed. The diffusion and flow laws of coal gangue slurry under the same inclination angle were summarized, and the field test of fluidization filling in the caving areas was conducted. The results show that: (1) The water-to-gangue ratio was the main controlling factor for the conveying performance of coal gangue slurry. The extensibility, slump, and bleeding rate of the coal gangue slurry increased with the increase of the water-to-gangue ratio. (2) The diffusion profile of coal gangue slurry at different dip angles was arc-shaped, and the diffusion distance of slurry increased with the increase of infiltration time. However, there were differences in the sustained diffusion ability of different dip angles. (3) At the same time interval, the spatial accumulation patterns of scattered gangue in different regions will lead to differences in the diffusion speed of the slurry. (4) Both burying and hanging pipes in the falling area can safely and efficiently fill the gangue slurry. The diffusion distance of the caving areas in the test working face was basically consistent with the diffusion distance of the slurry in the simulation test of the coal gangue slurry caving areas.

Experimental study on the characteristics, rheological factors, and flowability of MK-GGBFS geopolymer slurry

In this study, we investigated the effects of concentration and modulus of alkaline activator, liquid–solid (L/S) ratio, and sand volume fraction on rheological properties and flowability of metakaolin (MK)–ground granulated blast furnace slag (GGBFS) geopolymer slurry (pastes and mortars). The rheological property of geopolymer slurry was consistent with the Bingham model. A decrease in the modulus and the L/S ratio, or an increase in the concentration increased the plastic viscosity of geopolymer paste. The geopolymer pastes with higher plastic viscosity exhibited a lower fluidity. The yield stress of geopolymer paste was negatively correlated with concentration, modulus, and L/S ratio. An increase in the sand volume fraction increased the plastic viscosity and yield stress of geopolymer mortar, and decreased the consistency and fluidity of that. Moreover, the correlation between rheological parameters of the geopolymer mortar and paste, and the relationship between the flowability parameters and rheological parameters of geopolymer slurry were constructed.

Forecasting Strength Parameters of Hardened Geopolymer Slurries Applied to Seal Casing Columns in Boreholes

Ensuring effective sealing of casing columns in boreholes requires the use of the appropriate technology of cement slurry injection into the annular space and the use of a properly designed cement slurry recipe. Very often, when selecting the technological parameters of the cement slurry, special attention is paid to the technological parameters of the fresh cement slurry, but little attention is paid to the mechanical parameters of the cement sheath that is being formed (the cement slurry after setting). In order to improve the parameters of the hardened cement slurry in the annular space, the cement slurry of a new generation with increased durability (so-called geopolymers) is used. Slurries based on geopolymers are obtained by modifying slurries based on common-use cements with mineral additives with pozzolanic or hydraulic properties. Most often, these additives are fly ashes from the combustion of hard coal or ground granulated blast furnace slags. The article presents the results of testing the mechanical parameters of hardened cement slurries prepared on the basis of CEM V multi-component cement. It was found that the increase in the amount of silica fly ash in the slurry causes a delay in the strength growth rate; such slurries have lower values of early strength. The water–cement coefficient has the strongest influence on the mechanical parameters. The test results are also statistically developed, thanks to which it is possible to select the appropriate mathematical model, and this enables the prediction of mechanical parameters for slurries as a function of their hardening time. Such a mathematical solution can save some labor-intensive research, which, however, cannot be omitted in the final stage of slurry design.

Experimental and Numerical Studies of Self-Expansible Polyurethane Slurry Diffusion Behavior in a Fracture Considering the Slurry Temperature

Polyurethane grouting material (polymer) has been widely used in rock mass fracture grouting. The previous test of polymer slurry grouting in planar fracture did not consider the influence of temperature; therefore, in this paper, a test of polymer slurry grouting in planar fracture was firstly conducted in order to explore the diffusion characteristics of polymer slurry. The results show that the preheating temperature of polymer slurry has a great influence on the diffusion of slurry in fractures, which should be considered in the research of polymer fracture grouting. In addition, the slurry temperature is related to the chemical reaction of the polymer itself. However, the existing polymer fracture grouting models ignore the influence of temperature and the chemical reaction of the polymer slurry itself, which lack the rationality to reveal the diffusion behavior of the polymer slurry in fracture. Therefore, in this paper, a chemical reaction-fluid dynamic (CF) model was established. In addition, the Particle Swarm Optimization (PSO) algorithm was used to obtain the chemical reaction kinetic parameters of the polymer slurry. Based on the CF model, the diffusion characteristics of the polymer slurry during the fracture diffusion process were calculated. The applicability of the CF model was verified by comparing the experimental data with the calculated results. Finally, the influence of polymer preheating temperature and ambient temperature on slurry fracture grouting behavior was explored by the CF model. The research in this article provides some theoretical reference for the design of grouting parameters in fracture grouting engineering.

Effect of Mono-Dispersed Solids Slurry Characteristics on Horizontal Bends

Abstract: Erosion in multiphase flow due to the effect of solid particles is a key factor in wearing of industrial pipelines. In recent years, industries are using Computational Fluid Dynamics to study erosion wear in pipelines. Researchers have investigated various factors that affect the erosion of pipelines including particle size, velocity, coating material, fluid viscosity, region of pipe (bends/fittings convex or concave), etc. This paper investigates the effect of various slurry parameters on the rate of material erosion in the pipeline, under different sets of operation conditions. Silica sand (density= 2650 kg/m3 ) slurry was considered for the simulations, mixed in water at different volumetric concentration (12%, 24% and 36%), with an inlet velocity of 2.74 m/s and 3.56 m/s. The particle size was considered constant at 225µm, 450µm and 675µm, respectively. Simulations are done in ANSYS-FLUENT software under Eulerian two-phase model with k-ε approach. Results showed that the erosion rate followed the trend of increasing with an increase in all the above mentioned varying parameters as it varied from 8.25 mm/yr to 18.93 mm/yr. It was also hinted that as particle size reduced, the influence of velocity as a contributing parameter reduced which is explained by the fact that the mixture is leading from suspension state to colloidal state.

Direct ink writing of textured piezoelectric ceramics

Textured ceramics are often formed via tape casting in order to align platelet particles in the preferred direction, allowing the ceramic to have properties approaching those of single crystals without the complexities of growing such a crystal. However, tape casting produces significant waste material, as flat plates are machined to produce the desired geometries, e.g., rings. Additive manufacturing reduces these issues by allowing the complex geometries to be formed in the green state, thus reducing waste and improving design freedom. This presentation will discuss progress to-date on direct ink writing (DIW) of textured PMN-PZT. The focus will be on the methodology used to develop a suitable paste for printing. Development of a stable, shear thinning paste with a quick recovery time is critical. Zeta potential and rheological data were collected as a function of pH and other relevant slurry parameters such as percent solids loading and binder content. Sintered filaments and bulk parts were characterized to evaluate the efficacy of template alignment in the process as a function of slurry rheology, nozzle geometry, and print parameters.

Numerical study on the hydrodynamic properties of bentonite slurries with Herschel-Bulkley-Papanastasiou rheology model

During the construction of slurry shield tunnels, bentonite slurries play a significant part in maintaining excavation face stability where suitable slurries infiltrate into the stratum to form an impermeable filter cake. To enhance filter cake quality, accurate prediction of the hydrodynamic properties of bentonite slurries is always required during slurry parameters design. The main purpose of this study is to investigate the flow characteristics of bentonite slurries with different polymer contents using computational fluid dynamics (CFD) simulation. Mixtures of sodium bentonite powder, carboxymethyl cellulose (CMC), and water in different ratios were prepared, and a series of indoor rheological tests were conducted. Then an optimized numerical method for slurry flow simulation was developed by incorporating the Herschel- Bulkley-Papanastasiou (HBP) rheology model with the finite volume method (FVM). The proposed model was implanted in OpenFOAM, and then applied to theoretical cases of non-Newtonian plane-Poiseuille flow for model verification. Results show the theoretical and simulation results were in good accordance, with a successful description of the shear thinning characteristics of fluids and no divergency during the numerical solution procedure. Based on it, CFD simulations were implemented to investigate pipe flow characteristics of bentonite slurries with different CMC contents. Results indicate when the inlet velocity is constant, the decrease of pipe diameter can cause a more inhomogeneous flow and the growth of pressure drop; rises in rheological parameters can all increase the energy consumption and reduce the infiltration distance. When the yield stress is 25 Pa, the pressure drop reaches a maximum value of 5.47 kPa, compared with 2.69 kPa for slurries with a yield stress of 5 Pa. Furthermore, the infiltration law of bentonite slurries in pipes essentially conforms to a non-Darcy infiltration with an initial hydraulic gradient i0, which has a positive relationship with yield stress of fluids. i0 increases from 0.082 to 0.414 after adding 0.3% CMC into bentonite slurries. This research can provide significant guidance for the establishment of slurry infiltration theories and relevant numerical simulations.