Slurry Particles Research Articles

CHARACTERIZATION AND ADSORPTION PROPERTIES OF HYPERICUM PERFORATUM L. FOR THE REMOVAL OF Cu2+ IONS FROM AQUEOUS SOLUTIONS

The objective of the present study is the characterization of an adsorbent plant material based on Hypericum perforatum L. and the investigation of its feasibility for the removal of Cu2+ ions from aqueous solutions. XRD, TGA, FTIR, SEM and low-temperature nitrogen adsorption were used for the analytical characterization of the material. Particle size distribution and slurry pH of the investigated material were also determined. The effect of contact time, solution acidity and initial metal concentration on the adsorption of Cu(II) ions was studied by means of the batch method. Desorption studies have also been performed. Equilibrium experimental data were fitted to the linear Langmuir, Freundlich and Dubinin-Radushkevich isotherm models. The maximum adsorption capacity was calculated and it was concluded that the material could be used as an effective biosorbent for the removal of copper ions from aqueous media.

Effect of wet grinded lithium slag on compressive strength and hydration of sulphoaluminate cement system

As a by-products of lithium carbonate industry, emission of lithium slag (LS) was increasingly increased due to the huge market demand of lithium salt. Therefore, LS disposal faces great challenge. In the study, a new approach to use LS in sulphoaluminate cement (SAC) system to improve the early compressive strength was proposed. Nano-lithium slag (nano-LS) was prepared via wet grinding, and the effect of nano-LS on hydration mechanism of SAC was investigated. The results indicated that nano-LS with D50 of 300 nm was prepared. In comparison with the Blank, 4.0% nano-LS promoted the 7 h compressive strength from 4.5 MPa to 24.3 MPa, with an increase by more than 4 times, and an increase by 28% at 1 d age; it also reduced the initial and final setting time to 16 min and 23 min, being reduced by 33.3% and 37.5%. This phenomenon was because nano-LS accelerated the hydration of SAC, and 4.0% dosage even made the inducing period disappear. The reason for the accelerated hydration was that the nano particles in nano-LS slurry acted as excellent nucleation seeds for speeding of the formation of hydration products. Additionally, the promoted dissolution of lithium salt during the process of wet milling also facilitated precipitation of aluminum phase to accelerate the SAC hydration. Consequently, nano-LS was expected as an excellent accelerator in SAC system. All of findings suggested an innovation new way to utilize LS in SAC system.

Development of dark-field dynamic light scattering microscopy and its application: Tracking dynamics of particles in condensed slurries spreading on planar/nonplanar substrates

HypothesisWhile dynamics of particles in slurries is usually evaluated by dynamic light scattering measurements, this technique had only been applicable to particles in the bulk slurries. Because this limitation is mainly owing to strong reflection of light, the dynamics of particles in slurries spreading/drying on solid substrates is to be obtained by spatially separating the reflection light from scattering (signal) light. This may allow us to track the particles in practical samples such as cosmetics or inks spreading on solid surfaces. ExperimentWe developed novel “dark-field dynamic light scattering microscopy”. The system was evaluated with test samples of polystyrene beads dispersed in several viscosities of bulk glycerol aqueous solutions. This setup was then applied to slurries spreading/drying on planar and nonplanar substrates. FindingsThe results for planar surface indicate that origin of coffee-ring are the particles flowing into the edge of the droplet just before complete drying. On a skin-modelled nonplanar substrate, the slurry on bumps was found to maintain semi-dry condition longer than that at dents. This suggests that the dispersive medium was supplied to bumps from dents. This unique flow was explained as effective drying from the bumps increased surface tension at the bumps to pull up the liquid around.

Simulation Analysis of Erosion–Corrosion Behaviors of Elbow under Gas-Solid Two-Phase Flow Conditions

In the production and gathering process of coal gas, the complex composition of the coal gas, harsh environments, the complex medium, and high content of solid particles in slurry cause the equipment malfunctions and even failure because of erosion and corrosion. In the present study, COMSOL multi-physics finite element simulation software is used to simulate the erosion–corrosion behaviors of elbow in key chemical equipments. The electrochemical corrosion, solid particle erosion, chemical reaction, and turbulent flow are coupled together. The particle count method is proposed to clarify the erosion phenomenon. The simulation results show that particles with high turbulent intensity hit the wall of elbow directly, which forms a slanted elliptical erosion zone on the extrados surface at 40°–50°. The chemical reaction in turbulence has a difference in the concentration distribution of substances, and this phenomenon leads to different magnitudes of the corrosion current densities in the tube. Moreover, 1/6 released particles hit the extrados surface of the elbow. These findings are beneficial to understand the erosion–corrosion phenomena and design the elbow in key chemical equipment.

Polydispersity‐Driven Printing of Conformal Solid Metal Traces on Non‐Adhering Biological Surfaces

AbstractMetals and organics possess two very dissimilar surface energies, hence, do not naturally adhere to each other. This incompatibility is exacerbated by surface roughness yet advances in wearables and bioelectronics call for their integration. Mesoscale mechanical bonds, however, transcend the necessities of surface energy matching while taking advantage of surface texture. Herein, transient carrier fluids, particle size polydispersity, and capillary‐driven autonomous size‐sorting are exploited to conformally jam undercooled liquid metal particles on textured soft substrate. The well packed undercooled metal particles are then chemically activated to induce phase change, leading to a solid electrically conductive metal trace. Static and dynamic deposition of the particles is amenable to this surface‐templated printing of conductive traces. This process allows for printing across surfaces with varying surface features like on the brain, on paper (asymmetric porosity), or across smooth and rough brain sections. By tuning particle size and slurry concentration, good particle packing is demonstrated on a multi‐scale rough surface like a rose flower. This printing method is therefore compatible with delicate (low modulus), heat sensitive, and textured substrates hence compatible with biological tissues and organic substrates.

Universal inherent fluctuations in statistical counting of large particles in slurry used for semiconductor manufacturing

In the chemical mechanical polishing process of semiconductor manufacturing, the concentration of ‘large’ particles (ge 0.5 μm) in the slurry, which is considerably larger in size than the main abrasives (approx 0.1 μm), is a critical parameter that strongly influences manufacturing defects, yields, and reliabilities of large-scale-integrated circuits. Various instruments, so-called particle counters, based on light scattering, light extinction, and holography techniques have been developed to measure and monitor the large particle concentration in semiconductor fabs in real time. However, sizeable fluctuation in the measured particle concentration complicates the statistical process control in the fabs worldwide. Here, we show that an inherent fluctuation exists in the counting of large particles, which is universal, independent of instrument type, and quantitatively determined by the instrument’s operation parameters. We analytically derive a statistical theory of the fluctuation based on Poisson statistics and validate the theory through experiments and Monte-Carlo simulation. Furthermore, we provide a strategy to enhance the measurement accuracy by statistically adjusting the instrumental parameters commonly involved in the particle counters. The present results and analyses could be useful for statistical process control in semiconductor fabs to prevent large particle-induced defects such as micro-scratches and pits on wafers.

High-resolution numerical modelling of a marine mine tailings discharge in Western Norway

Waste from mining operations includes mine tailings, a slurry of fine-grained mineral particles and processing chemicals that remains after the desired compounds have been extracted from the ore. In some cases, the method of disposal is to place tailings into the marine environment; this is known as Submarine Tailings Placement (STP). To understanding the environmental impact of releasing large amounts of mine tailings into the marine system, multiple processes must be well characterised, including those relating to the transport and fate of the disposed material.We applied a set of high-resolution models for wind, hydrodynamics, and sediment transport to simulate a submarine mine tailings discharge in a Norwegian fjord. The transport model includes processes to account for the effect of flocculation on mine tailings transport and fate. We calculated the mean tailings sedimentation rate in the fjord, which is closely related to the environmental footprint of the STP. Comparisons with measurements of winds, currents, turbidity, and sedimentation rates were made to evaluate the model, and we found overall reasonable agreement. We investigated discharge scenarios during 2013 and identified a strong wind event around November 17, which caused increased particle dispersal. The increased mixing caused by the strong winds were seen in elevated turbidity measurements, as well as increased modelled suspended sediment concentration.

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.

Исследование процесса получения суспензии частиц композиционного гидрогелевого материала

The paper presents comprehensive investigation results concerning obtaining a composite hydrogel material in the form of an aqueous slurry. We considered the issue of grinding hydrogel in water so as to obtain an aqueous slurry of hydrogel particles featuring the desired particle size distribution. We selected polyacrylamide to be the composite hydrogel material and used an anti-Stokes phosphor as a filler. We describe a multi-stage method for producing hydrogel, a coarse grinding process for hydrogel blocks, and a fine grinding technology employing an immersion disperser. We obtained slurries featuring a narrow particle size distribution (160--1000 µm). We provide data on investigating how the manufacturing process parameters and modal parameters of the equipment used affect the particle size distribution in the resulting hydrogel material. We propose a technology for producing composite hydrogel particle slurry in a single process cycle

CFD Modeling of Multi-Sized Particulate Slurry Flow through Pipe Bend

CFD Modeling of Multi-Sized Particulate Slurry Flow through Pipe Bend

Numerical simulation of coarse particle pipeline transportation based on Eulerian Lagrangian model

In this paper, based on the Eulerian Lagrangian model, the non-phase change flow process of the coarse particle slurry in the horizontal pipeline is studied. The particle motion state is tracked, the dynamic characteristics of the coarse particle slurry in the pipeline transportation are explored, and the resistance characteristics of the pipeline and the operation stability under different conditions are analyzed. The comparison of the results of velocity distribution, concentration distribution and pressure curve with the empirical formula and experimental data shows that the simulation results are in good agreement with the calculation results of wasp formula and the experimental values of Roco&Balakrishnam, and the simulation can better describe the flow characteristics in the basin. In addition, the flow characteristics of particles are further analyzed according to the key factors such as the flow stability, the transition process and the critical deposition velocity of particles in different positions of the pipeline.

Influences of media on dispersion behaviors and electrokinetic properties of nanoceria particles in concentrated slurries

Both dispersion behaviors and electrokinetic properties of nanoceria particles in concentrated slurries were researched with the ultrasound attenuation and electroacoustic technologies, and influences of dispersing media were analyzed. It was found that particle size distribution (PSD) of the nanoceria could be fitted well by the bimodal model with lower errors, and zeta potential of the particles could be obtained by direct measurements due to small primary size less than 50 nm. And the media had great influences on both dispersion behaviors and electrokinetic properties of the nanoceria particles in slurries. The nanoparticles could be dispersed to primary particles as a whole in the slurry with de-ionized water when they had absolute zeta potential higher than 30 mV, which accorded well with the Derjaguin-Landau-Verwey-Overbeek (DLVO) theory. But non-DLVO interactions would appear and complicate the situation in the slurry with polyelectrolytes. The practical analysis ascertained some basic details in ultrasound and electroacoustic measurement of nanoparticles in concentrated slurries, as well as microscopic mechanisms for dispersion of nanoparticles, both of which would promote understanding and optimizing dispersion behaviors of nanoparticles in concentrated slurries.

A Tubular Electrochemical Reactor for Slurry Electrodes.

The research on electrochemical reactors is mostly limited to planarly designed modules. In this study, we compare a tubular and a planar electrochemical reactor for the utilization of the slurry electrodes. Cylindrical formed geometries demonstrate a higher surface‐to‐volume ratio, which may be favorable in terms of current density and volumetric power density. A tubular shaped electrochemical reactor is designed with conductive static mixers to promote the slurry particle mixing, and the vanadium redox flow battery is selected as a showcase application. The new tubular design presents similar cell resistances to the previously designed planar battery and shows increased discharge polarization behavior up to 100 mA cm−2. The volumetric power density reaches up to 30 mW cm−3, which is two times higher than that of the planar one. The battery performance is further investigated and 85 % coulombic, 70 % voltage and 60 % energy efficiency is found at 15 mA cm−2 with 15 wt.% slurry content.

In situ liquid SIMS analysis of uranium oxide

Trace analysis of nuclear materials in solid particles collected in the environment or particles in liquid slurry generated in nuclear material manufacturing processes can pinpoint elemental, organic, and isotopic signatures of nuclear fuel cycle activities and processes. Such information can support nuclear safeguards programs by increasing our ability to detect undeclared nuclear materials, routine activities for safeguarding at declared facilities, and illicit activities. However, trace radioactive material analysis in liquids and slurries is challenging using bulk approaches. For example, one drawback of sensitive analysis such as inductively coupled plasma mass spectrometry (ICP‐MS) is that sample is consumed or destroyed as a result of the technical approach. We developed a vacuum compatible microfluidic interface to enable surface analysis of liquids and solid–liquid interactions using time‐of‐flight secondary ion mass spectrometry (ToF‐SIMS). In this work, we illustrate the initial results from the analysis of liquid uranium oxide standard solutions using in situ liquid SIMS. Because the liquid SIMS analysis is almost nondestructive, the same sample can then be analyzed by other analytical techniques or saved for future reference. Consequently, multimodal analysis is possible. Our results demonstrate that in situ liquid SIMS can be used as a new approach to analyze radioactive materials in liquid and slurry forms of relevance to diverse applications.

Parametric evaluation of a hydrofoil-shaped sidewall rib-employed microchannel heat sink with and without nano-encapsulated phase change material slurry as coolant

The application of hydrofoil-shaped sidewall ribs (SWRs) in microchannel heat sinks (MCHSs) with nano-encapsulated phase change material (NEPCM) particle slurry as coolant has recently been proven as an improvised solution for enhancing heat transfer, with a reasonable penalty in pressure drop. However, the further mitigation of high-power densities of modern micro/nanoscale devices is limited owing to manufacturing complications and design constraints. By using the geometrical and thermophysical parameters of hydrofoil-shaped SWRs and NEPCM slurry, the present study numerically evaluates the thermal and hydrodynamic performance of an MCHS device. The preliminary results reveal the superior performance of NEPCM slurry with hydrofoil-shaped SWRs compared with that of water without ribs in an MCHS owing to the improved latent heat storage capability of the former fluid as well as the enhanced heat transfer area of the rib structure. Increase in the width and height of hydrofoil-shaped SWRs and particle diameter, latent heat of fusion and mass concentration of the NEPCM slurry at a constant Reynolds number (Re) and inlet temperature enhances heat transfer. However, increase in the pitch of the hydrofoil-shaped SWRs and melting temperature range of the NEPCM slurry degrades heat transfer. The inlet temperature of the NEPCM slurry, with a slightly lower value than the melting point of the NEPCM particles, yields superior performance. The maximum ratios of the Nusselt number, that is, Nuavg,SWR/Nuavg,ref and Nuavg,NEPCM/Nuavg,ref, are 1.88 and 2.68, respectively. A particle loading of more than 10% at a high Re of 1000 is not reasonable from the thermodynamic efficiency perspective. The findings are expected to serve as a benchmark for the selection of the geometric, thermophysical and operational parameters of future MCHS devices with hydrofoil-shaped SWRs and NEPCM slurry as coolant.

Rheological and Hindered Settling Studies on Bimodal Mixture Based on Multi-size and Multi-density Slurry: Multi-component Viscosity Model Development

The behavior of the fine solid mixture in a fluid depends critically on its rheological property. The rheological properties of a mixture change based on factors like particle size distribution, shape, density, etc. In this paper, two different minerals with distinct densities and similar size distribution with its mixture at different proportions (i.e., at 10–90% of magnetite/chromite ore: silica) were used for settling and rheological studies. Experiments were piloted using both mono-density and dual component mixture having poly-dispersed sample sets at different solids percentage (10–60%) for the hindered settling studies followed by rheological studies in the double-gap rheometer setup in a controlled shear rate method. The viscosity of the slurry decreased with an increased percentage of heavier particles in the mixture. Using the experimental data set, the effect of component density on the rheology of a particulate slurry mixture was assessed, and a multi-component viscosity mathematical model was developed.

Fatigue of a SiC/SiC ceramic composite with an ytterbium‐disilicate environmental barrier coating at elevated temperature*

AbstractTension‐tension fatigue performance of a SiC/SiC composite with an ytterbium‐disilicate environmental barrier coating (EBC) was investigated at 1200°C in air and steam. The composite is reinforced with Hi‐Nicalon™ SiC fibers and has a melt‐infiltrated matrix processed by chemical vapor infiltration of SiC with subsequent infiltration with SiC particulate slurry and molten silicon. The EBC consists of a Si bond coat and an Yb2Si2O7 top coat applied via air plasma spraying. Tensile properties were evaluated at 1200°C. Tension‐tension fatigue was examined for maximum stresses of 110‐140 MPa. To assess the efficacy of EBC, experimental results obtained for the coated composite are compared to those for a control uncoated composite. Surface grit‐blasting inherent in the EBC application process degrades tensile strength of the composite. However, the EBC effectively protects the composite from oxidation embrittlement during cyclic loading in air or steam. Fatigue runout set to 200 000 cycles (55.6 hours at a frequency of 1.0 Hz) was achieved at 110 MPa in air and steam. Retained properties of pre‐fatigued specimens were characterized. Composite microstructure, along with damage and failure mechanisms were investigated. Damage and failure of the composite are attributed to the growth of cracks originating from numerous processing defects in the composite interior.

Experimental investigation on the effect of water-silica slurry impacts on 3D-Printed polylactic acid

The effect of water-silica slurry impacts on PolyLactic Acid (PLA) processed by Fused Deposition Modeling (FDM) under different conditions were investigated. The studied factors were building orientation, layer thickness, and slurry impact angle, where Taguchi design was used. The results showed an increase in the specimens’ weights after the slurry erosion tests. This weight gain was eventually attributed to the synergistic effect of water absorption and the embedment of solid particles within the specimens. An analysis of variance (ANOVA) test was conducted and concluded that the layer thickness and impact angle are the significant factors influencing the weight gain resulting from absorbed water. Moreover, impact angle was the most significant factor for the weight gain resulting from embedded slurry particles.

Rapid determination of toxic and rare-earth elements in teas by particle nebulization-ICPMS

Toxic elements profiling of teas is vital in terms of both quality control as well as a means to generate a comprehensive database for human-health-risk assessment. Accordingly, in the present study, a rapid method using direct nebulization of tea particles for inductively coupled plasma (ICP) ionization and subsequent detection of toxic elements by mass spectrometry (MS) was developed. Dried and well grounded tea particles were stably dispersed in 0.5% polyethylene-imine and the particle slurries were analyzed by ICP-MS using aqueous standard calibration. Monitoring the nebulization, transportation, and ionization behaviors of particles of different sizes revealed that particles with a mean size of 1 μm provide values comparable with those of aqueous standards containing equivalent concentrations of the analyte. The excellent recoveries of the method (90–105%) were verified by analyzing two tea certified reference materials, and the detection limits ranged from 0.03 (for Tm) to 1.2 (for Cr) μg kg−1. Then, we performed screening analysis of five toxic elements (As, Cd, Cr, Hg, and Pb) and 16 rare-earth elements in 20 Pu’er teas, and the results revealed that the contents of all the toxic elements and heavy rare earth oxides were low level, where those of the light rare-earth oxides were high. Furthermore, the total rare-earth oxides content of 30% of the Pu’er teas exceeded the Chinese National limit.

Controlling of Dispersion State of Particles in Slurry and Electrochemical Properties of Electrodes

The electrode materials which exhibit high capacity have attracted much attention because the capacity of the materials directly commits to the energy density of LIBs and driving miles of EVs. So that, many researchers devote their efforts to find new electrode materials with high capacity such as lithium excess layered oxide, Ni-rich materials and silicon. Electrode manufacturing process, generally consists of (1) preparing slurry, (2) coating the slurry on current collector, (3) drying, (4) pressing steps, is another important issue to achieve LIBs with high energy density.Compared with numerous reports described with the electrode material development, however, only the limited numbers of papers related to the electrode construction process have been published [1-5]. To shed light the relationship between the electrode construction process and the battery performance is an essential research for obtaining the best performance from electrode materials and assembled LIB cells.In the present study, we focused our attention on the slurry preparation step among above-mentioned four steps. The slurry preparation is the first step in the electrode construction process, and we recognize the dispersion state of particles achieved during slurry preparation greatly influences the battery performance.Three different preparation processes were applied to achieve the different dispersion state of particles in slurries, and thus obtained slurries are characterized by rheological measurement. It is found that dispersion process with highly loaded slurry or under high shear flow reduces elastic moduli and that their combination achieved the most dispersed state of the particles among the slurries investigated. X-ray computed tomography unveiled that the electrodes manufactured from these slurries contain the aggregates and the size of aggregates in the electrodes was reduced with the decrease in elastic moduli of slurry. At the discharge current density of 10 mA g–1, these electrodes exhibited 140 mAh g–1 of discharge capacities. At 1000 mA g–1, the electrode prepared from highly loaded slurry maintained 80% of the capacity that obtained at the current density of 10 mA g–1. The capacity of the electrode prepared from the slurry under highly loaded and high shear flow, on the other hand, dropped below 10%, indicated that the electrode from the most dispersed slurry has the worst rate performance.[Ref.]1) K. M. Kim et al., J. Power Sources, 83, 108 (1999).2) E. Ligneel et al., J. Electrochem. Soc., 154, A235 (2007).3) G.-W. Lee et al., J. Power Sources, 195, 6049 (2010).4) B. Bitsch et al., J. Power Sources, 265, 81 (2014).5) S. Lim et al., J. Power Sources, 299, 221 (2015).