Effect Of Particle Characteristics Research Articles

Effects of particle characteristics on the granulation ability of iron ores during the sintering process

The granulation behavior of iron ores is essential for subsequent parameter optimization and efficient granulation, especially under changing material conditions. In this study, the effects of surface properties and particle size were analyzed using a laboratory granulation method; an estimation of the granulation of sintering blends was subsequently conducted for the base ores. Circularity and porosity were observed to negatively affect the granulation of iron ores, whereas wettability positively affected the granulation and was the most influential factor, indicating that wetting of iron ores is desirable during granulation. When iron ores with complex size distributions were granulated, the equivalent surface area was the main influencing factor for coarse particles larger than 1 mm and the ratio of adhering fines to intermediates was the main factor for fine particles smaller than 1 mm. By combining the granulation of coarse and fine particles with their proportioning, we proposed a calculation method for estimating the granulation ability of sintering blends. Good verification was demonstrated with the designed schemes. The results suggest that the developed method is effective for predicting the granulation of iron ore mixtures.

Microfiltration of humic-rich water coagulated with cationic polymer: The effects of particle characteristics on the membrane performance

The main issue explored was the effects of different coagulation conditions on the particle characteristics that would also significantly affect the performance of membranes when filtering coagulated humic-rich water. The size distribution and morphological properties of flocs formed through the coagulation of natural organic matter (NOM) were characterized and the impact of Ca2+ on these characteristics and on the performance of the MF membrane was determined. The multi-cycle MF experiments with hydraulic wash between cycles were conducted for raw and coagulated humic-rich water, and the performance was evaluated by measuring the permeate water quality, resistance to filtration, and permeability recovery with cleaning. Coagulant (polydiallyldimethyl-ammonium chloride) additions from 50% to 100% of the charge neutralization dose substantially decreased fouling compared to when filtering raw humic-rich water. Short-term fouling was increased when 1mM Ca2+ was added, but the charge neutralization coagulation removed almost all of the fouling tendency that had occurred when filtering Ca-NOM and resulted in the highest permeability recovery. The median diameter and the two-dimensional fractal dimension of flocs produced were increased as the zeta potential reached close to zero, which resulted in the formation of a cake layer that was easily removed from the surface of the membrane.

Effects of particle characteristics on homogeneity of green bodies in powder injection moulding

A homogeneous powder and binder distribution in the green body in powder injection moulding (PIM) is important. In the present study, the mould filling model of PIM has been developed, based on the multiphase fluid theory, viscosity model of feedstock and powder-binder drag force model. The particle Reynolds number is influenced by the particle size and density, resulting in the different drag force between powder and binder. Furthermore, the varied velocity of binder and powder will be obtained with numerical calculation of the continuity equations, leading to the change of green body homogeneity. CFX was used to simulate the mould filling in PIM. The results showed that the homogeneity of green bodies was relative to the filling patterns, which varied with different powder densities. The powders were not suitable for PIM when the particle size was bigger than 20 μm, and the fine powders were beneficial to improve the homogeneity.

Rheology of Concentrated Tomato-Derived Suspensions: Effects of Particle Characteristics

In the present work, the effect of particle properties on the rheological behaviour of tomato-derived suspensions was investigated systematically. Hereto, a range of relatively monodisperse suspensions, containing either cell fragments or single cells with varying average particle size (∼148, 267, 303 and 393 μm) and pulp content (from 25 to 60 wt.%), was prepared by the reconstitution of tomato tissue-based particles in water. The effect of the presence of a serum phase on the rheological properties of tomato-derived suspensions was investigated by the comparison of the rheology of reconstituted tomato purees in water with those in serum. All the tomato-derived suspensions were non-Newtonian liquids exhibiting a yield stress. The flow behaviour could be described well by the Herschel–Bulkley model. The undisrupted network structure of all suspensions could be classified as a weak gel with a rather low critical strain. Particle concentration, size and morphology (surface/shape) turned out to be key structural properties controlling the rheological parameters of these tomato-derived suspensions. Increase in yield stress and storage modulus with particle concentration could be fitted to a power law model. The ratio of static yield stress to dynamic yield stress turned out to be larger for particles with a more irregular, less intact surface, showing the enhanced tendency of the latter particles to build up structure in rest conditions. A unique linear relation was found between the static yield stress and the maximal elastic stress in oscillatory tests, independent of the particle properties. Finally, replacing the serum phase by water led to a substantial decrease in network strength, especially in quiescent conditions.

Effects of particle characteristics on magnetic immunoassay in a thin channel

The effects of size and porosity of particles on magnetic immunoassay in a thin channel were studied. Experimental parameters were investigated and compared using a model immunoassay complex of carcinoembryonic antigen (CEA)/anti-CEA. The rate constant for the affinity reaction between functional particles increased as the size of magnetic nanoparticles (800–80nm) decreased. The affinity reaction between functional particles had no significant effect on the sizes of microparticles (1.0–4.4μm) at commonly used thin channel flow-rates of 0.001–0.025ml/min. Competitive and sandwich reactions of CEA/anti-CEA were studied for CEA detection. Microparticles of different porosities produced similar linear ranges of detection and limits of detection. The limits of detection for CEA were 0.29pg/ml and 0.21pg/ml for competitive and sandwich reactions, respectively. The linear ranges of detection were from 0.49pg/ml to 4.9ng/ml for both competitive and sandwich reactions. The detection limits were lower, and the linear ranges were wider than those of literature. There was a 9% difference in CEA detection measurements between competitive and sandwich magnetic immunoassay. The measurements of two magnetic immunoassays differed by less than 13% from the ELISA reference measurements. The running time was less than 30min. Magnetic immunoassay in a thin channel has great potential for biochemical analysis and immunoassay-related applications.

Effect of particle characteristics on deformation of particle reinforced metal matrix composites

Abstract The particle characteristics of 15% SiC particles reinforced metal matrix composites (MMC) made by powder metallurgy route were studied by using a statistical method. In the analysis, the approach for estimation of the characteristics of particles was presented. The study was carried out by using the mathematic software MATLAB to calculate the area and perimeter of each particle, in which the image processing technique was employed. Based on the calculations, the sizes and shape factors of each particle were investigated respectively. Additionally, the finite element model (FEM) was established on the basis of the actual microstructure. The contour plots of von Mises effective stress and strain in matrix and particles were presented in calculations for considering the influence of microstructure on the deformation behavior of MMC. Moreover, the contour maps of the maximum stress of particles and the maximum plastic strain of matrix in the vicinity of particles were introduced respectively.

Effects of Particle Characteristics on the Viscous Properties of Granular Materials in Shear

The viscous properties of a wide variety of unbound granular materials (GMs) were evaluated by drained shear tests. The specimens were reconstituted ones that were loose or dense and air-dried or moist or saturated, of mostly natural sands and gravels, having different mean particle diameters, uniformity coefficients, fines contents, degrees of particle angularity and particle crushabilities. The tests were mostly triaxial compression (TC) tests and partly plane strain compression tests, both at fixed confining pressure, and direct shear tests at fixed normal pressure. The viscous properties of GMs were evaluated by stepwise changing the loading rate and performing sustained loading (SL) tests during otherwise monotonic loading (ML) at a constant loading rate. The viscous properties are characterised in terms of the rate-sensitivity coefficient (β), the viscosity type parameter (θ=βr/β) and the decay parameter (r1). Correlations among these parameters and effects of particle characteristics on these parameters are analysed. Creep strains are compared with residual strains by cyclic loading under otherwise the same TC conditions. As the particles become less angular, as the grading becomes more uniform and as the particles become less crushable, the viscosity type deviates more from the Isotach type (i.e., θ=1.0) changing toward the P & N type (i.e., θ<0) associated with a decrease in β and r1, while creep strains by SL decreases and residual strains by many unload/reload cycles increases. It is shown that the loading rate effects observed in the experiments can be simulated well by the three-component model taking into account the effects of particle characteristics on the viscous property parameters.

Low Defect Ceria for ILD CMP

ABSTRACTThe reduction of wafer scratching is a key goal driving the commercial development of CMP slurries. To better understand the underlying abrasive particle properties critical to the scratch performance of ILD CMP slurries, the scratching behavior of ceria slurries prepared with a range of particle size characteristics are characterized. Scratch results are presented and two effects are proposed to account for the findings. The Removal Rate Effect relies solely on the observed inverse proportionality between scratching and removal rate. This interpretation is consistent with a simple surface balance of scratches but suggests that removal rate differences dominate scratch performance. The Managed Tail Effect considers the effect of particle characteristics on both the creation and the removal of scratches. For a given particle population, the larger particles are assumed to dominate scratch creation. However, larger particles are also seen to drive removal rate which affects the removal of scratches during polishing. This interpretation implies that optimal scratch performance for a ceria ILD CMP slurry will be obtained when the width of the ceria particle's size distribution is optimized relative to its mean.

CMR 2005: 8.06: Contrast‐assisted ultrasound for sentinel lymph node detection; the effect of particle characteristics and node status on imaging efficacy

CMR 2005: 8.06: Contrast‐assisted ultrasound for sentinel lymph node detection; the effect of particle characteristics and node status on imaging efficacy

Ultrasonic control of ceramic membrane fouling: Effect of particle characteristics

In this study, the effect of particle characteristics on the ultrasonic control of membrane fouling was investigated. Ultrasound at 20 kHz was applied to a cross-flow filtration system with γ-alumina membranes in the presence of colloidal silica particles. Experimental results indicated that particle concentration affected the ability of ultrasound to control membrane fouling, with less effective control of fouling at higher particle concentrations. Measurements of sound wave intensity and images of the cavitation region indicated that particles induced additional cavitation bubbles near the ultrasonic source, which resulted in less turbulence reaching the membrane surface and subsequently less effective control of fouling. When silica particles were modified to be hydrophobic, greater inducement of cavitation bubbles near the ultrasonic source occurred for a fixed concentration, also resulting in less effective control of fouling. Particle size influenced the cleaning ability of ultrasound, with better permeate recovery observed with larger particles. Particle size did not affect sound wave intensity, suggesting that the more effective control of fouling by large particles was due to greater lift and cross-flow drag forces on larger particles compared to smaller particles.

Modelling of cohesive granular flow in powder processing

Several polymer processing operations such as rotational moulding and powder coating involve avalanching flow of granular materials. The objective of this work is to develop a model and simulate mixing and segregation of granular particles during such flow. The movement of particles has been modelled using the Monte Carlo approach. Important forces such as interparticle friction, adhesion and electrostatic forces have been incorporated in the simulation. Simulation results show segregation in the bed as a result of size differences and are consistent with published results for cohesionless systems. The simulation allows for the quantitative evaluation of the effects of particle characteristics and material properties on the flow behaviour of granular materials during processing, which, otherwise, could not easily be determined experimentally. Results showed that the gradual development of cohesive forces inhibits the movement of particles and can lead to the development of reverse segregation patterns.

Evaluation of Bubble Content in Aqueous Alumina Slurries

Entrapped air bubble is one of the main defects in slurry processing of ceramics. For preventing bubble occurrence or removing them efficiently, an improved knowledge of bubble behaviors in slurries is indispensable. In this paper, effects of particle characteristics, solid loading and dispersant concentration on bubble content in aqueous alumina slurries were studied experimentally. The results showed that the characteristics of initial powders, i.e. particle size distribution and shape, significantly affected the bubble content in slurries. The bubble contents were drastically enhanced by smaller and irregular particles with a higher specific surface area. Moreover, the bubble contents were also greatly increased with increasing solid loadings, and this influence was more pronounced for the particles with a higher specific surface area. No noticeable change in bubble content was resulted from varying the dispersant concentration. A new parameter, solid surface area per unit volume of slurry has been introduced to interpret these effects of powders. It is found that the bubble content shows a parabolic increase as a function of the parameter.

Measurement and Prediction of Pressure Drop in Pneumatic Conveying: Effect of Particle Characteristics, Mass Loading, and Reynolds Number

This paper reports the effect of Reynolds number, mass loading, and particle shape and size on pressure drop in a vertical gas−solids pneumatic conveying line. We isolate the effect of one variable while holding all others constant. A commonly used pressure drop correlation and a state-of-the-art multiphase computational fluid dynamics (CFD) models are then assessed by comparing their predictions to experimental data. Deficiencies in the models and the correlation are identified, and possible modifications are proposed. The most notable deficiency is the inability of both the experimental correlation and the CFD model to accurately predict the pressure drop for gas−solids flow with highly aspherical particles.

The effects of particle characteristics on emissions from burning wood fuel powder

Wood fuel powders cut in different mills were combusted in a 150 kW burner to study emissions, furnace temperature and burnout as a function of particle size distribution and particle shape. Particle characteristics only slightly influenced NO x formation but more strongly influenced fuel feeding, ignition, unburned pollutants and furnace temperature. The lowest NO x emissions achieved was <50 mg/MJ. For finely milled wood powder, CO emissions had the lowest values (21 mg/MJ). Varying the ratio between primary, secondary and tertiary airflows, slightly influenced the combustion results using a small-scale powder burner.

Effect of particle characteristics on particle pickup velocity

Particle entrainment is investigated by measuring the velocity required to pick up particles from rest, also known as pickup velocity. Pickup velocity is a function of individual particle characteristics and interparticle forces. Although 5–200 μm particles are investigated, the work presented here focuses on the pickup of particles in a pile in the size range of 5–35 μm. These smaller particle sizes are more typical for pharmaceutical and biomedical applications, such as dry powder inhalers (DPIs). Pickup velocities varied from 3.9 to 16.9 m/s for the range of particle sizes investigated. There is a strong correlation between particle size and the dominating forces that determine the magnitude of the pickup velocity. Preliminary data investigating pickup velocity as a function of particle size indicate the existence of a minimum pickup velocity. For larger particle sizes, the mass of the particle demands a greater fluid velocity for entrainment, and for smaller particle sizes, greater fluid velocities are required to overcome particle–particle interactions. Pickup velocity remains relatively constant at very small particle diameters, specifically, less than 10 μm for glass spheres and 20 μm for nonspherical alumina powder. This can be attributed to the negligible changes in London–van der Waals forces due to a hypothesized decrease in interparticle spacing. At intermediate particle diameters, electrostatic forces are dominant.

Formation and Structure of Polyelectrolyte and Nanoparticle Multilayers: Effect of Particle Characteristics

The formation and structure of multilayer films containing a cationic polyelectrolyte and anionic silica nanoparticles were studied by means of ellipsometry and atomic force microscopy. Three types of silica particles of different sizes were examined. The density and thickness of the films as well as the adsorption kinetics appear to be strongly dependent on the choice of particle; smaller particles favor the formation of smooth and dense films with a higher content of the inorganic component.

The effects of particle characteristics on three-body abrasive wear

The effects of abrasive particle characteristics, especially shape and hardness, on three-body abrasive wear of metallic samples have been investigated. The experimental tests were carried out on a modified pin-on-disc tribometer using dry abrasive particles and on a ball-on-plate tribometer using slurry. Spike parameter quadratic fit (SPQ) was used in the characterization of particles angularity. Better correlation between wear rates and particle angularity was found in ball-on-plate tests. The noted exception was quartz that generated less wear in all the tests than could be expected from its high SPQ value. Additional characteristics such as particle toughness, orientation in the contact, and embedment in the worn surfaces affected the wear results. Damage due to rolling (indentation) wear prevailed on the plate samples from ball-on-plate tests, whereas both sliding and rolling wear was found on the cylindrical samples from modified pin-on-disc tests. The morphology of worn surfaces correlated well with the shapes of abrasive particles. Rounded particles generated round craters and smooth grooves while angular particles produced sharp indents and narrow cutting grooves.

Effect of particle characteristics on flowability of fine powders: R.M.German et al. (Pennsylvania State University, USA.)

Effect of particle characteristics on flowability of fine powders: R.M.German et al. (Pennsylvania State University, USA.)

Corn Grits Particle Size and Distribution Effects on the Characteristics of Expanded Extrudates

ABSTRACTThe effects of corn particle size and distribution on the ex trusion‐cooking process was studied. Extrusion cooking was carried out in a twin‐screw corotating extruder. The effects of particle characteristics were studied by analyzing process responses on‐line, by expansion indices, mechanical (puncture test) and structural (computerized image analysis) prop erties of the extrudate. An increase in particle size for a given biochemical composition gave extrudates that were harder, with a modified expansion and lower cell density. The par ticle size distribution in the range studied was not significant. Correlations were found between expansion indices and process responses.

The effect of particle characteristics on the beam attenuation coefficient and output from an optical backscatter sensor

Experiments were conducted to measure optical backscatter and beam transmission of suspensions of 180, 150 and 90 μm sand, and 40 μm clay, in a recirculation tank designed to house an optical backscatterance sensor (O.B.S.) and a beam transmissometer. Particle size was determined using gravimetric techniques and Coulter counter. By contriving known sediment distributions from the fractionated sediment samples, it was found that both the O.B.S. and beam transmissometer responded approximately linearly to narrow band and broad band particle suspensions. The beam transmissometer showed greater sensitivity to the fine-grain fraction of a poly-disperse suspension than the O.B.S.