Silica Sand Particles Research Articles

Study on the hydrate growth characteristics and rheology of silica-containing sand water-in-oil emulsion system

Understanding the transportability of silica-sand-containing hydrate slurries is crucial for production safety of non-consolidated natural gas hydrate reservoirs, especially when solid-state fluidization technology is utilized. Despite some research on silica sand and marine sediments’ influence on hydrate formation kinetics, rheological studies are scarce for systems with silica sands. The formation process of cyclopentane hydrates under the coexistence of hydrophilic silica particles and surfactants were observed. The effects of the concentration and particle size of silica sands as well as the water cut and surfactant concentration of emulsion on the rheological properties of hydrate slurries were investigated using a rheometer. The results indicated: (1) Hydrophilic sand aggregates were entrapped in water droplets, indirectly affecting the oil–water contact area due to the increase in water droplet volume, which was conducive to the combination of alkanes and water molecules to form a hydrate shell; silica particles provided nucleation sites at the oil–water interface to promote the adsorption and aggregation of cyclopentane molecules. (2) The synergistic effect of silica sand and surfactants significantly shortened the induction time of hydrates and increased the viscosity of the slurry. As the concentration of silica sand (1 wt%, 5 wt%, 10 wt%) increased, the induction time of hydrate formation decreased by 44.8 min. Within the concentration range below 5 wt%, the viscosity of the slurry increased as the concentration increased, with an amplitude of 13830.7 mPa·s. The induction time of hydrate formation decreased with increasing silica sand particle size (2 μm, 6.5 μm, 12 μm), but the size of silica sand particles had no significant effect on the viscosity of the slurry. (3) Hydrate slurries in all systems exhibited shear-thinning behavior. There was no obvious relationship between the yield stress of slurry under different silica sand concentrations. However, the yield stress of the slurry was inversely proportional to the size of silica sand particles. The yield stress decreased by 141.13 Pa when the size of silica sand particles increased from 2 μm to 12 μm. Overall, this study highlighted the influence of silica sand presence on flow safety assurance in solid-state fluidization technology.

Experimental study of erosion in heat exchangers immersed in fluidized beds

Fluidized beds can be used as solar energy receivers in beam-down concentrated solar power plants. The fact that solid particles can withstand temperatures over 1,000°C is promising because it would mean higher thermal efficiencies than conventional concentrated solar power plants (CSP, that use molten salts, whose maximum operating temperature is limited to about 560°C). Nonetheless, immersed heat exchangers are exposed to erosion because fluidized particles impinge on their surfaces. The multiple variables of a multiphase flow and the uncertainties of the material detachment process make erosion a complex problem that stills not fully solved.The aim of this study is to conceive an experimental procedure to measure erosion on cylindrical probes immersed in a lab-scale high temperature fluidized bed (able to operate up to 1,000°C and atmospheric pressure), simulating a tube of a heat exchanger in a fluidized bed working at expected temperatures in CSP applications.Preliminary results at ambient temperature are presented in this study. Silica sand particles were fluidized with air and erosion was measured on cylindrical probes made of aluminium 5027. Silica sand was characterized with a microscope before and after each test to determine its size distribution and shape. Several parameters (diameter, mass, and circumferential profile) of each probe were also studied before and after each test. Different fluidization velocities were implemented to assess the influence of the flow rate on erosion.

Synergistic effects of cold rolling and age hardening on the hardness and tensile characteristics of AA6061 hybrid composites

The present study involves the fabrication of aluminium alloy 6061 matrix hybrid composites with varying weight fractions of silica sand and copper particles by employing the conventional stir casting method. The combined influence of age hardening (AH) and low temperature thermomechanical treatment (LTMT) on the hardness and tensile properties of AA6061 hybrid composites was investigated. The uniform dispersion of the particles in the matrix was confirmed by microstructure analysis and the improvement of Brinell hardness values. The composites exhibited higher tensile strength and hardness than the base alloy. Both AH and LTMT enhanced the properties of the hybrid composites and a comparison between them revealed the best results for LTMT hybrid composites. The LTMT hybrid composite with 3 wt% silica sand and 3 wt% copper (3S3C) subjected to 12% rolling deformation and aged at 100 °C had the highest hardness and tensile strength of 144.26 HV and 290 MPa respectively. The hardness and tensile strength of AA6061-3S3C hybrid composite subjected to LTMT in peak aged condition showed an improvement of 125 and 97% respectively when compared with those of AA6061 alloy. Fracture surface analysis of the thermomechanical treated composites in peak aged condition showed a mixed mode of failure dominant with the ductile fracture.

Effect of Silica Size on the Relative Wear of Microstructures Containing Solidification Carbides and Tempered Martensite Using a Dry Sand Rubber Wheel Test

The objective of this study was to examine the impact of the size of silica sand particles on the wear resistance of two microstructures containing solidification M7C3 carbides in tempered martensite matrix (namely, AISI D2 steel and high-chromium white cast iron). Wear tests were conducted using abrasive silica sand particles of three different sizes (0.20, 0.50, and 1.0 mm) in a dry sand rubber wheel tribometer (DSRW) following the ASTM G65 standard. Subsequently, these samples were analyzed using microscopy and three-dimensional optical profilometry. The results showed that the wear loss increased with increased abrasive particle size, particularly when the abrasive size increased from 0.5 to 1.0 mm. The microscopic observation revealed silica sand incrustation and plastic deformation of the tempered martensite matrix, cracking of the solidification M7C3 carbides, and detachment of the carbides and matrix. Furthermore, the largest abrasive particle size triggered a more damaging wear mechanism, leading to severe fracture damage of the solidification carbides.

Numerical investigation of mixing and heat transfer of mixed biomass and silica sand particles in a bubbling fluidized bed combustor

Using fluidized bed combustion technology, biomass is being promoted for electricity production. However, a lack of biomass in a particular location or season poses a problem, leading to low thermal efficiency when using a single biomass. Thus, mixed biomass is considered a potential solution. This study uses CFD-DEM simulation to investigate the effects of various biomass types, loadings, and blending ratios on hydrodynamics and heat transfer in a bubbling fluidized bed. Coarse bagasse size provides the most efficient mixing behavior for a single biomass mixture. A blending ratio of 1:3 wood chip to coarse bagasse with 5% biomass loading, using 1 mm silica sand, is the appropriate condition. The primary factor for mixing is the difference in biomass sizes, while different biomass loadings have no significant influence. Smaller sand particles enhance the mixing and heat transfer. These findings provide useful guidelines for efficient biomass conditions in fluidized bed combustors.

The Effects of Silica Sand Particle Size on Drying Using a Vertical Fluid Bed Dryer

The experimental and theoretical relationships of silica sand particle size and drying was compared to predict the minimum fluidization rate in drying at 9.57% moisture. The drying temperature (90°C, 120°C, and 150°C) and particle size (274 ± 0.5 μm, 563 ± 0.5 μm, and 910 ± 0.5 μm) parameters were studied as factors influencing the drying process in the experiment. Upon comparing all the test results, it was found that moisture loss accelerated as drying temperature of the silica sand samples increased. On the other hand, the minimum fluidization rate was found to have varied directly with particle size, in addition to being inversely proportional to temperature. Moreover, it was observed that pressure increased with increasing particle diameter and reduced with decreasing temperature.

Wettability, flowability and core bending strength of wet silica sand particles based on the interfacial properties of liquid silicate binders

The flowability of wet silica sand particles containing liquid binders, which are among the new moulding materials for green casting, must be further improved. Herein, we conducted an in-depth study on the interface characteristics of silicate binders with the addition of anionic surfactants. Through particle flow experiments and sand core bending fracture experiments, the influence of anionic surfactants on the flow characteristics of wet sand particles and the mechanical properties of silicate-bonded sand was explored. The experimental results showed that the addition of 0.10 wt% of an anionic surfactant significantly reduced the surface tension and contact angle of solutions, from 78.99 to 28.53 mN/m, and from 49.9° to 34.4°. Moreover, compared with unmodified wet particles, the flowability of wet particles modified with 0.10 wt% of the anionic surfactant was improved to some extent. However, the flexural strength of silicate-bonded sand was also reduced to a certain extent.

Multiple Hydrogen Bonding-Assisted High-Strength Hydrogel of Silica/Polyacrylamide Nanocomposite Cross-Linked with Polyethylenimine.

The nanocomposite gel system has been successfully applied as a water shutoff agent to enhance oil recovery (EOR) or for plugging to control lost circulation events. In this study, the silica/polyacrylamide nanocomposite was synthesized via in situ free radical polymerization of acrylamide (AM) monomers in the presence of silica nanoparticles. The composite was cross-linked with polyethylenimine to prepare a high-strength hydrogel. The viscosity test was conducted to determine the gelation time of the gel. Rheological measurements and sand pack breakthrough pressure tests were carried out to measure the gel strength. Attenuated total reflectance-Fourier transform infrared (ATR-FTIR) and scanning electron microscopy (SEM) tests were adopted to characterize the structure and morphology of the gel. The results show that compared to polyacrylamide (PAM) gel, the gelation time of the nanocomposite gel will decrease with increasing gel elasticity modulus, and the breakthrough pressure of the nanocomposite gel is 29.82 MPa, which increased by 65%. As shown in the ATR-FTIR test, this can be attributed to the presence of multiple hydrogen bonds for the PAM molecule with both silica and quartz sand particles. In the composite gel, hydrogen bonding mainly forms between the O atoms of PAM and the H atom on the surface of silica, enhancing gel strength and elasticity modulus with more cross-linking density and less porosity. Moreover, H bonding between additional -NH2 of PAM and quartz sand particles helps improve gel plugging pressure. However, in the silica and PAM mixture gel, the H bonding of silica occupies -NH2 of PAM, which became unavailable to attach on the sand surface, reducing the breakthrough pressure by 30%, although it can enhance the rheological strength. This study suggests that in situ composite of silica in PAM can not only greatly improve gel rheological strength but also help maintain the strong adhesion of PAM molecules onto quartz sand, resulting in better plugging performance in the sand reservoir.

Experimental Investigation on Particle Breakage Behavior of Marine Silica Sand under High-Stress Triaxial Shear

There is often obvious particle breakage for silica sand under high-stress, which will lead to the bearing capacity reduction and excessive settlement of the foundation. This paper focuses on the particle breakage characteristics of marine silica sand from the East China Sea under high-stress conditions. A series of conventional triaxial tests for silica sand, including consolidated drained (CD) and consolidated undrained (CU) shear tests, were conducted under the confining pressures in the range of 2–8 MPa to investigate the breakage rule during the shearing process. The developments of particle breakage index Br with axial strain ε1 and volumetric strain εv present hyperbolic and linear trends, respectively. A hyperbolic model was adopted to describe the relationship of Br and ε1 and the corresponding model parameters were obtained. The particle breakage index also has a good correlation with the input work per unit volume under various average stresses, regardless of the stress history. Furthermore, the relationship between the fractal dimension and the particle breakage was studied based on the particle size distribution curve. It is concluded that the fractal dimension increases in an up–convex hyperbolic trend with the increase of particle breakage index. The dividing radius for whether the silica sand particles exhibit the fractal features is determined as approximately 0.4 mm. This is anticipated to provide reference and supplementary test data for analyzing sand constitutive models/environments regarding particle crushing.

Erosion wear assessment of sugarcane fibre reinforced polymer composites for applications of wind turbine blades

This research reports erosion wear characteristics of polyester matrix composite reinforced with short fibres of sugar cane. Erosion tests were conducted using silica sand particles of size (200–500 µm) using a locally designed air jet-type erosion test rig. The sugarcane fibre-reinforced polyester composites (5% wt.) with different fibre lengths (3, 12, 48 mm) were impacted by sand particles at a fixed velocity of 60 m/s, impact angles (30°, 60°, 90°) and erodent weight of (2500,7500) gm. ANOVA approach was used to determine the most significant parameter and their combinations that minimize the erosion rate. Scanning Electron Microscope (SEM) observations were conducted to investigate the erosion mechanisms. Results indicated that the erosion rate is greatly influenced by fibre length as well as the erodent weight. Moreover, at an erodent weight of 2500gm, the behaviour of the material turns from brittle into ductile. At an erodent weight of 7500gm, the erosion rate is inversely proportional to the fibre length.

Tensile properties of PVA and PE fiber reinforced engineered cementitious composites containing coarse silica sand

To mitigate the shrinkage of engineered cementitious composites, coarse silica sand has been employed to substitute ultrafine silica sand in recent years. However, for the different matrix strengths and fiber types, the mechanism of coarse silica sand on ECC tensile performance is different. In this paper, coarse silica sand was introduced into PVA fiber (PVA-ECCs) and PE fiber reinforced ECCs (PE-ECCs), and the impact of silica sand with different particle sizes on the tensile properties of PVA-ECCs and PE-ECCs was investigated. Results indicate that a larger size of silica sand leads to more and larger pores and a looser matrix, which is not conducive to fiber dispersion and fiber/matrix interfacial bonding, resulting in a reduction in tensile strength. Additionally, increasing the silica sand particle size can availably decrease the matrix fracture toughness of PE-ECCs, making the matrix more prone to cracking, promoting saturation cracking behavior and increasing tensile strain capacity, whereas PVA-ECCs have the opposite trend. Moreover, microstructural analyses using SEM were conducted to analyze the impact of coarse silica sand and ultrafine silica sand on the tensile behaviors.

Solid particle erosion evaluation of automotive paint coatings under the influence of artificial weathering

Solid particle erosion (SPE) is one of the most critical tribological problems causing damage to automotive paint coatings. The correct characterization of SPE and resistance against it makes the possible extended service life of the coating, increasing the resale value of cars. Car manufacturers and paint industries have developed new techniques to apply coatings and coatings that improve the initial and long-term appearance, scratch performance, and durability of coatings. Several works have focused on studying the degradation and performance of paint coatings. However, there needs to be more understanding of wear progress under different environmental degradation conditions. This study investigates the mechanisms and resistance of erosive wear of actual automotive paint coatings before and after exposure to an accelerated weathering process. Steel substrate panels with a typical paint coating system were exposed to weathering degradation by UV and immersion in an artificial acid rain solution. The chemical changes induced in the coatings were analyzed by FT-IR spectroscopy. Then erosive tests were carried out using silica sand particles at two different angles of incidence (30° and 90°) and temperatures (25 °C and 60 °C) for both samples (unexposed and weathering conditions). The SPE rate was determined for each coating by mass loss estimation using an analytical balance; meanwhile, wear mechanisms were analyzed in detail by SEM. The results showed decreased SPE resistance promoted by chemical changes in samples exposed to both weathering processes.

Experimental and mesoscale analysis on wave propagation induced by impact in dry silica sand

When investigating the propagation of stress waves in sand-like materials, the materials are generally modeled as homogeneous parts despite their complex structures comprising numerous particles of varying sizes and shapes. However, this approach fails to consider the non-continuum nature of sand-like materials. To address this issue, a mesoscale numerical model of silica sand particles with random shapes and three sizes is employed in this study to numerically analyze wave propagation. Experimental data from an upgraded split Hopkinson pressure bar test are utilized to validate the accuracy of the numerical model. Using the validated numerical model, we investigate the impact of relative densities, incident wavelengths, and wave amplitudes on stress wave attenuation in dry silica sand. Empirical equations are derived from summarizing the stress wave attenuation law induced by impact loading. The study shows that relative density and wavelength are critical factors affecting the residual peak stress ratio in silica sand, while the effect of loading wave amplitude is limited.

Automatic Flushing Strainer-Type Filter: A Method for Actual Filtration Grade Assessment

Proper filtration selection, sizing, maintenance, and performance of a filtration system are crucial for removing suspended solids in water, preventing clogging of emitters, and ensuring a high-performing microirrigation system throughout its lifespan. Filtration prevents the intake of particles larger than the pore size specified in a given filtration grade. Proper selection of the filter media ensures efficient solid–liquid separation. Strainer-type or screen filters have elements composed of a woven or nonwoven cloth of numerous weave types. The material and characteristics of the screen directly affect the fluid flow and filter performance. The aim of this study is to propose a method for determining the actual filtration grade of filters used for irrigation. An automatic flushing strainer-type filter was equipped with five filter element models, composed of woven and nonwoven materials, for evaluation. A new methodology was developed to assess the actual filtration grade based on the removal efficiency for suspended solids under controlled and repeatable conditions. The removal efficiency of each filter element was determined for particle size ranges defined according to the filtration grade declared by the manufacturer. The proposed methodology allowed for the assessment of the actual filtration grade of each model of filter element operated with water containing suspended particles of silica sand. The filtration grade declared by the manufacturer was confirmed for some of the filter elements, but it could be modified for others. The proposed methodology could be useful for assessing the actual filtration grades of screen, disk, and media filters.

A study of the multi-scale compression behaviour of a sand immersed in a viscous liquid

Pore fluids with different viscosities can exist in soils. While the effects of pore fluids have been investigated at the macro-scale, little is known about how they might affect the micromechanics. A novel apparatus allowing a single particle to be crushed while immersed in a liquid was built here. With the help of a high-speed microscope camera, the crushing processes of single silica sand particles immersed in glycerine were captured and the breakage modes were clarified. The immersion in glycerine leads to stronger particles with higher strains at failure compared with immersion in water or exposure to air. Moreover, the results of constant rate strain oedometer tests revealed that saturation in glycerine made the sample significantly stiffer in compression as a result of less particle breakage compared with that in water or under dry conditions. The lower particle breakage at the macro-scale appeared to correspond to the higher strengths measured at the micro-scale.

Mechanical characterization of low temperature thermomechanical treated AA6061-silica sand composites

In the present work efforts are made to confirm the effects of reinforcement and thermomechanical treatment (TMT) on the mechanical properties of aluminium matrix composite (AMC) produced through stir casting technique. Silica sand particles with varying weight percentages were used to fabricate the composites and the extracted particle analysis revealed the retention of a minimum of 97% of reinforcement particles. The composites are subjected to conventional age hardening and low temperature thermomechanical treatment (LTMT) to enhance their mechanical properties. The mechanical characterization of the composites subjected to heat treatment processes include hardness and tensile tests. Nearly 20–30% increase in peak hardness, 30% decrease in aging time and 15% increase in ultimate tensile strength (UTS) was observed in LTMT treated composites as compared to age hardened composites. The best results of peak hardness and UTS of 139.76 HV and 274 MPa respectively were achieved by composite containing 6 wt.% silica sand reinforcement subjected to 15% deformation and aged at 100 °C.

A study of snow drifting on monoslope roofs during snowfall: Wind tunnel test and numerical simulation

The insight into the influences of roof slope on the characteristics of snow drifting on monoslope roofs during snowfall is still inadequate so far. Scaled tests of snow drifting on monoslope roofs with varying slopes (0° to 25°) were thus carried out in a wind tunnel equipped with a snowfall simulator, employing silica sand particles to model the snow precipitation environment. Typical snowdrift patterns on monoslope roofs were summarized, and elaborations were provided on the variation for the characteristics of snow drifting with roof slope. Similar features in terms of particle distributions, transport rate, and degree of erosion are observed for lower-sloped roofs (0°, 5°, and 10°), which all differ from those on higher-sloped roofs (15°, 20°, and 25°). The difference caused by the variation of approaching wind velocity on particle erosion is found to be more pronounced compared with that of snowfall intensity, and the increase in the degree of erosion with snowfall intensity can be reasonably represented by the linear relationship. The flow pattern around the roof and surface friction velocity before (without snow) and after snowfall (with snow cover) were then explored via numerical simulation for different roof slopes. Based on the simulated flow characteristics, the mechanisms of snow drifting on the sloped roofs under snowfall were further discussed.

Experiment Study of the Evolution of Coral Sand Particle Clouds in Water

The motion of particle clouds (i.e., sediment clouds) usually can be found in engineering applications such as wastewater discharge, land reclamation, and marine bed capping. In this paper, a series of laboratory tests are conducted on coral sand to investigate the shape feature of the single particle and the mixing processes of the coral sand particle clouds. The shape of coral sand particle is measured and quantified. The experimental results demonstrate that the shape of coral sand particles tends to be spherical as the particle size decreases, and empirical equations were established to explain the variation of D50 and fS,50 of coral sand. Compared with the silica sand, the evolution of the coral sand particle cloud still experiences three stages, but the threshold for the Reynolds number of particle clouds entering the next stage changes. Further, the normalized axial distance of the coral sand particle clouds is 58% smaller. The frontal velocity exhibits similar varying tendency for the coral sand particle cloud. Considering the difference in shape between coral sand particles and silica sand particles, a semi-empirical formula was proposed based on the original silica sand prediction formula by adding the shape factor and the experimental data of 122 µm⩽D50⩽842 µm. It can predict the frontal velocity of the coral sand particle clouds.

Filtration characteristics with parameter variation for dust removal from syngas

BackgroundGranular bed filter technology is a newly emerging field, and the science is in its infancy. There is a lack of background information on these consistencies. This study provides new insights into clean processing, which is useful in hot gas cleanup technology. MethodsWe employed a moving granular bed filter, which is evaluated in two separate performance studies: (1) optimization of particle removal efficiency and bed pressure drop under different movement velocities of silica sand; and (2) high temperature model simulation conducted dust and Silica sand flow rates and superficial velocity. Besides, this evaluated the filter system's dynamic characteristics by measuring variations in the outlet concentration and size distribution of dust particulates. Significant findingsThe results indicated that the filtered dust in the silica sand considerably affected the dust via inertial impaction and diffusion. With higher movement velocity of silica sand, the higher specific resistance coefficient of k1 and k2 caused better performance of collection mechanism, thereby enhancing the removal efficiency. Consequently, this study observations indicated that at a high movement velocity of silica sand, the gas velocity favors dust attachment on the silica sand particle surface, facilitating dust removal.The purpose of this study is to investigate the efficiency of moving granular bed filter (MGBF) in high-temperature environment under different operation conditions. The effects of the test temperature and movement velocities of silica sand on the dust size distribution and removal efficiency were studied; further, an experimental system comprising a high-temperature environment of 600 °C was established for a filter system. The removal efficiency was enhanced at a test temperature of 25 °C when considering a gas velocity of 500 mm/s and a movement velocity of silica sand of 1.95 mm/s. The test results showed that an improvement in the movement velocity of silica sand decreased the temperature of the bed, increasing the removal efficiency. Furthermore, this study could be used in different high-temperature filter systems for gas cleanup.

Experimental measurement of particle crushing around model piles jacked in a calibration chamber

During installation of driven or jacked piles in sand, particle crushing occurs in a region below the base of these piles. Quantification of the degree and extent of particle crushing during driving or jacking in sand is necessary to improve current design methods. To study the effects of particle crushing on the capacity of piles jacked in uniform silica sand samples, a model pile was jacked and tested in a half-cylindrical calibration chamber with transparent observation windows in its front wall. Annular samples of crushed sand 3 mm in thickness were recovered after testing from several locations along the shaft and the base of the model piles and used to assess particle gradation changes and to calculate breakage parameters. Relationships between the load mobilized at the base of the model piles and three breakage parameters are proposed. Furthermore, the number of jacking strokes (ranging from 1 to 32 in this research) has a negligible effect on the degree of crushing produced during installation and on the measured stresses at the base of the model pile. Analyses of the digital images captured during pile jacking indicate that the silica sand particles in the path of the model pile crush mainly along irregularities and sharp edges. Different zones are identified below the model pile according to the degree of particle crushing. Digital images taken during static loading of the model pile allowed tracking of the displacement paths of individual sand particles during loading.