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O emprego da análise de imagem na determinação da distribuição de tamanho de partículas da areia presente no esgoto sanitário; The use of image analysis to determine particle size distribution of grit carried by sewage

PRADO, Gustavo Silva do; CAMPOS, José Roberto
Fonte: ABES Publicador: ABES
Tipo: Artigo de Revista Científica
POR
Relevância na Pesquisa
95.95%
É consensual, no meio técnico, que unidades de desarenação devem reter partículas discretas de elevada velocidade relativa de sedimentação (por exemplo: areia, silte, cinzas, semente de frutas etc); e que desarenadores capazes de remover grãos de areia de tamanho maior ou igual a 0,2 mm removem a maior parte dos materiais que ocasionam problemas operacionais em estações de tratamento de esgoto (ETE). Entretanto, não existe concordância acerca da forma de se determinar a concentração ou a distribuição granulométrica de tais materiais no esgoto sanitário. O presente artigo apresenta um método para determinar a distribuição granulométrica da areia presente no esgoto sanitário, o qual se baseia no emprego de técnicas de análise de imagens digitais. A aplicação do método proposto demonstrou que, em média, 84% da massa de areia carreada pelo esgoto sanitário afluente da ETE Jardim das Flores (Rio Claro, SP) era composta por partículas maiores ou iguais a 0,2 mm.; There is a consensus among technicians that degritters ought to remove discrete particles which present elevated settling velocities (e.g. sand, silt, ashes, fruit seeds etc.) and that units which are able to retain particles larger than or equal to 0.2 mm remove most of the material which causes operational problems to wastewater treatment plants (WWTP). Nevertheless...

Comparative physical-chemical characterization of encapsulated lipid-based isotretinoin products assessed by particle size distribution and thermal behavior analyses

GUIMARAES, Carla Aiolfi; MENAA, Farid; MENAA, Bouzid; QUENCA-GUILLEN, Joyce S.; MATOS, Jivaldo do Rosario; Mercuri, Lucildes Pita; Braz, Andre Borges; ROSSETTI, Fabia Cristina; KEDOR-HACKMANN, Erika Rosa Maria; SANTORO, Maria Ines Rocha Miritello
Fonte: ELSEVIER SCIENCE BV Publicador: ELSEVIER SCIENCE BV
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
95.88%
Isotretinoin is the drug of choice for the management of severe recalcitrant nodular acne. Nevertheless, some of its physical-chemical properties are still poorly known. Hence, the aim of our study consisted to comparatively evaluate the particle size distribution (PSD) and characterize the thermal behavior of the three encapsulated isotretinoin products in oil suspension (one reference and two generics) commercialized in Brazil. Here, we show that the PSD, estimated by laser diffraction and by polarized light microscopy, differed between the generics and the reference product. However, the thermal behavior of the three products, determined by thermogravimetry (TGA), differential thermal (DTA) analyses and differential scanning calorimetry (DSC), displayed no significant changes and were more thermostable than the isotretinoin standard used as internal control. Thus, our study suggests that PSD analyses in isotretinoin lipid-based formulations should be routinely performed in order to improve their quality and bioavailability. (C) 2010 Elsevier B.V. All rights reserved.; CNPq (National Council for Scientific and Technological Development); CAPES (Coordination of Perfectioning Staff of Superior Level)

Caracterização e distribuição espacial dos sedimentos depositados numa zona ripária reflorestada; Sediment morphology and distribution in a reforested riparian zone

Momoli, Renata Santos
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 10/10/2006 PT
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As atividades agrícolas no Estado de São Paulo, foram responsáveis pela supressão da cobertura vegetal original do solo e, sua conseqüente degradação. A vegetação nativa foi gradativamente substituída por culturas como café, pastagem, citros e cana-de-açúcar, durante séculos de ocupação e uso da terra. A recomposição da cobertura florestal auxilia na prevenção da erosão do solo e na redução dos impactos causados. A floresta ripária retém os sedimentos resultantes do desprendimento do solo à montante e transportados pela enxurrada. A deposição de sedimentos na zona ripária está relacionada à pluviosidade, às feições geomorfológicas, ao material de origem e manejo da área à montante. O padrão de distribuição de sedimentos na zona ripária reflete a dinâmica da deposição e os prováveis processos ocorridos. Para inferir sobre os processos de deposição ocorridos, foram realizadas análises macro e micromorfológicas e, também análises granulométricas apoiadas na interpretação estatística dos parâmetros de Folk & Ward (1957). As amostras de solo foram dispersas em Hexametafosfato de Sódio e também em água, para simular as condições de campo, seguindo a metodologia de Camargo (1986). Os resultados obtidos através da análise granulométrica...

Influência da distribuição granulométrica no empacotamento de matérias-primas na formulação de porcelânicos.; Influence of particle size distribution in the packaging of raw materials for porcelain formulation.

Conceição, Edilene de Souza
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 26/07/2011 PT
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Materiais complexos como porcelanas e porcelanatos tem suas propriedades maximizadas quando atingem altas densidades finais após a sinterização. Contudo, a sua formulação contém no mínimo quatro matérias- primas diferentes, sendo o caulim a maior parte, mas também contendo quartzo e feldspatos. A granulometria final da mistura é controlada por uma única etapa de moagem de todos os materiais misturados. O objetivo deste trabalho foi obter combinações de diferentes granulometrias de ortoclásio, albita e quartzo com uma única granulometria de caulim através de cálculos de máximo empacotamento com o objetivo de alcançar a máxima densidade a cru, mantendo-se uma única composição química final. Os resultados mostraram que utilizando o conceito de empacotamento de partículas e otimizando a distribuição granulométrica foi possível obter corpos de prova com maiores densidades finais, menor retração final, além de reduzir a temperatura de queima, o que impacta diretamente no custo de produção.; Complex materials such as porcelain and porcelain stoneware have maximized their properties when they reach high final densities after sintering. However, formulations contain at least four different raw materials...

Multifractal characterization of saprolite particle-size distributions after topsoil removal

Miranda, J. G. V.; Montero, E.; Alves, M. C.; Gonzalez, A. Paz; Vazquez, E. Vidal
Fonte: Elsevier B.V. Publicador: Elsevier B.V.
Tipo: Artigo de Revista Científica Formato: 373-385
ENG
Relevância na Pesquisa
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Multifractal analysis is now increasingly used to characterize soil properties as it may provide more information than a single fractal model. During the building of a large reservoir on the Parana River (Brazil), a highly weathered soil profile was excavated to a depth between 5 and 8 m. Excavation resulted in an abandoned area with saprolite materials and, in this area, an experimental field was established to assess the effectiveness of different soil rehabilitation treatments. The experimental design consisted of randomized blocks. The aim of this work was to characterize particle-size distributions of the saprolite material and use the information obtained to assess between-block variability. Particle-size distributions of the experimental plots were characterized by multifractal techniques. Ninety-six soil samples were analyzed routinely for particle-size distribution by laser diffractometry in a range of scales, varying from 0.390 to 2000 mu m. Six different textural classes (USDA) were identified with a clay content ranging from 16.9% to 58.4%. Multifractal models described reasonably well the scaling properties of particle-size distributions of the saprolite material. This material exhibits a high entropy dimension, D-1. Parameters derived from the left side (q > 0) of the f(alpha) spectra...

Pore size evolution during sintering of ceramic oxides

Varela, José Arana; Whittemore, O. J.; Longo, Elson
Fonte: Universidade Estadual Paulista Publicador: Universidade Estadual Paulista
Tipo: Artigo de Revista Científica Formato: 177-189
ENG
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This paper reviews the influence of particle size distribution, agglomerates, rearrangement, sintering atmospheres and impurities on the pore evolution of some commonly studied oxides. These factors largely affect sintering mechanisms due to modifications of diffusion coefficients or evaporation-condensation. Very broad particle size distribution leads to grain growth and agglomerates densify first. Rearrangement of particles due to neck asymmetry mainly in the early stage of sintering is responsible for a high rate of densification in the first minutes of sintering by collapse of large pores. Sintering atmospheres play an important role in both densification and pore evolution. The chemical interaction of water molecules with several oxides like MgO, ZnO and SnO2 largely affects surface diffusion. As a consequence, there is an increase in the rates of pore growth and densification for MgO and ZnO and in the rate of pore growth for SnO2. Carbon dioxide does not affect the rate of sintering of MgO but greatly affects both rates of pore growth and densification of ZnO. Oxygen concentration in the atmosphere can especially affect semiconductor oxides but significantly affects the rate of pore growth of SnO2. Impurities like chlorine ions increase the rate of pore growth in MgO due to evaporation of HCl and Mg(OH)Cl...

Influence of the particle size and animal slurry type on the potential of nitrogen mineralization after soil incorporation

Fangueiro, D.; Gusmão, M.; Grilo, J.; Vasconcelos, E.; Cabral, F.
Fonte: Cordovil, C. e Ferreira, L. Publicador: Cordovil, C. e Ferreira, L.
Tipo: Conferência ou Objeto de Conferência
Publicado em /09/2010 ENG
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RAMIRAN International Conference; Animal manures are rich in organic matter and nutrients, namely nitrogen (N) and, consequently, widely applied to soil as organic fertilizers. However, a large part of the nitrogen contained in animal manures is in the organic form and so not directly available for plants. Indeed, organic N has to be mineralized prior to plant uptake (Rees and Castle, 2002). Several manure characteristics as the C:N ratio (Chadwick et al., 2000), the lignin content (Kristensen, 1996) and the NH4 +/organic N ratio (Beauchamp and Paul, 1989) have been suggested as indicators of the plant-available N. More recently, Fangueiro et al. (2008) showed that the potential of N mineralization (PNM) of cattle slurry is inversely correlated with slurry particle size: finest fractions are the particle-size fractions from which N mineralization occurs in slurries whereas coarser fractions are associated with immobilization. Furthermore, Moller et al. (2002) reported that animal diet and anaerobic decomposition during storage in slurry channels and stores affect the slurry particle size distribution. Such information is of great interest since the finest slurry particle size should infiltrate the soil more easily and quickly relative to the coarser slurry particle size that should remain close to soil surface. Furthermore...

FRACTAL SCALING OF PARTICLE AND PORE SIZE DISTRIBUTIONS AND ITS RELATION TO SOIL HYDRAULIC CONDUCTIVITY

BACCHI,O.O.S.; REICHARDT,K.; VILLA NOVA,N.A.
Fonte: São Paulo - Escola Superior de Agricultura "Luiz de Queiroz" Publicador: São Paulo - Escola Superior de Agricultura "Luiz de Queiroz"
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/05/1996 EN
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Fractal scaling has been applied to soils, both for void and solid phases, as an approach to characterize the porous arrangement, attempting to relate particle-size distribution to soil water retention and soil water dynamic properties. One important point of such an analysis is the assumption that the void space geometry of soils reflects its solid phase geometry, taking into account that soil pores are lined by the full range of particles, and that their fractal dimension, which expresses their tortuosity, could be evaluated by the fractal scaling of particle-size distribution. Other authors already concluded that although fractal scaling plays an important role in soil water retention and porosity, particle-size distribution alone is not sufficient to evaluate the fractal structure of porosity. It is also recommended to examine the relationship between fractal properties of solids and of voids, and in some special cases, look for an equivalence of both fractal dimensions. In the present paper data of 42 soil samples were analyzed in order to compare fractal dimensions of pore-size distribution, evaluated by soil water retention curves (SWRC) of soils, with fractal dimensions of soil particle-size distributions (PSD), taking the hydraulic conductivity as a standard variable for the comparison...

Mathematical modeling of polystyrene particle size distribution produced by suspension polymerization

Machado,R.A.F.; Pinto,J.C.; Araújo,P.H.H.; Bolzan,A.
Fonte: Brazilian Society of Chemical Engineering Publicador: Brazilian Society of Chemical Engineering
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/12/2000 EN
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Particle size distribution (PSD) of polystyrene particles produced by suspension polymerization is of fundamental importance in determining suspension stability and product quality attributes. Within a population balance framework, a model is proposed for suspension polymerization reactors to describe the evolution of the PSD. The model includes description of breakage and coalescence rates in terms of reaction kinetics and rheology of the dispersed phase. The model is validated with experimental data of styrene suspension polymerization.

Analysis of tecniques for measurement of the size distribution of solid particles

Arouca,F. O.; Barrozo,M. A. S.; Damasceno,J. J. R.
Fonte: Brazilian Society of Chemical Engineering Publicador: Brazilian Society of Chemical Engineering
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/03/2005 EN
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Determination of the size distribution of solid particles is fundamental for analysis of the performance several pieces of equipment used for solid-fluid separation. The main objective of this work is to compare the results obtained with two traditional methods for determination of the size grade distribution of powdery solids: the gamma-ray attenuation technique (GRAT) and the LADEQ test tube technique. The effect of draining the suspension in the two techniques used was also analyzed. The GRAT can supply the particle size distribution of solids through the monitoring of solid concentration in experiments on batch settling of diluted suspensions. The results show that use of the peristaltic pump in the GRAT and the LADEQ methods produced a significant difference between the values obtained for the parameters of the particle size model.

Effects of binary particle size distribution on the fluid dynamic behavior of fluidized, vibrated and vibrofluidized beds

Daleffe,R. V.; Ferreira,M. C.; Freire,J. T.
Fonte: Brazilian Society of Chemical Engineering Publicador: Brazilian Society of Chemical Engineering
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/03/2008 EN
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In this work the effects of particle size distribution on the dynamics and segregation patterns in fluidized, vibrated and vibrofluidized beds were investigated. A binary particle size distribution and a reference one composed of glass spheres with a mean Sauter diameter of 2.18×10-3 m were tested. The experimental setup consisted basically of a circular glass chamber with a height of 0.50 m and a diameter of 0.114 m, operated in the fluidized bed mode (gamma = 0.00), in either vibrated or vibrofluidized bed modes (gamma = 2.00). The pressure drops in the fluidized and vibrofluidized beds were not significantly affected by the binary particle size distribution. Well-defined segregation patterns occurred in fluidized and vibrated beds with small particles concentrating at the top and large particles at the bottom in the first situation and the reverse in the second one. Segregation patterns in vibrofluidized beds depended on the values of vibration parameters. Segregation in vibrofluidized and vibrated beds was minimized by operating at a high amplitude of vibration.

Particle size distribution reconstruction: the moment surface method

Hutton, Kieran W; Mitchell, Niall A; Frawley, Patrick J
Fonte: Elsevier Publicador: Elsevier
Tipo: info:eu-repo/semantics/article; all_ul_research; ul_published_reviewed
ENG
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peer-reviewed; Numerical simulation of typical chemical engineering processes, such as crystallisation, liquid-liquid extraction, milling and other multi-phase operations in which exist discrete and continuous phases are highly computationally intensive problems. For this reason numerical techniques, such as the Method of Moments (MOM) and Quadrature Method of Moments (QMOM), are utilised to improve the computational efficiency of these simulations. The downside to these approaches is that the simulations only produce the moments of the Particle Size Distribution (PSD), with the actual distribution not preserved. Knowledge of the PSD is very important for many industrial unit operations, particularly in dynamic multi-phase flows in chemical engineering where the composition of the discrete phase(s) evolves in time or space. For example, control of the PSD in crystallisation operations may be required to ensure more efficient downstream operations such as filtration and clarification. Several methods for the reconstruction of a distribution from its respective moments are available in the literature. Typically these techniques are quite computationally expensive. The novel technique presented in this paper involves the pre-calculation of the moments of a pre-defined 2-parameter Probability Density Function (PDF) for a range of values of each parameter. This pre-calculation results in moment surfaces where the surfaces are a function of the two defining parameters. The intersection of constant moment contour lines (termed moment iso-lines) on these surfaces using simulation moment outputs results in the recovery of the defining parameters. Knowledge of the PDF and the total particle count or solids loading allows for the reconstruction of the full PSD. This technique proves to be very efficient which makes it ideal for the reconstruction of large numbers of distributions...

Effect of particle size on the flow properties of a South Australian coal-water slurry

Nguyen, Q.; Logos, C.
Fonte: Elsevier Science Publicador: Elsevier Science
Tipo: Artigo de Revista Científica
Publicado em //1996 EN
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86.03%
The rheological behaviour of a low-rank coal-water slurry from Lochiel, South Australia, has been studied as a function of solids concentration, particle size and size distribution. Coal slurries consisting of particles finer than 45 μm suspended in water were found to exhibit a wide spectrum of flow behaviour ranging from Newtonian as low solids concentrations to shear-thinning and viscoplastic with a yield stress at higher concentrations. By adding a narrow-sized coarse coal fraction (208–279 μm) to the fine coal slurry, the flow characteristic of the slurry, at a fixed total solids concentrations, could be changed significantly with a substantial reduction in the slurry viscosity. An optimum coarse-to-fine particle ratio of 40:60 exists at which the slurry is Newtonian with a minimum viscosity of a about 5 times lower than the viscosity of a slurry containing only fine particles at the same solids concentration. A further reduction in the slurry viscosity of 50% was achieved by adding a second coarse coal particle (279–325 μm) to the bimodal slurry. The significant improvement in the rheological behaviour with changing the particle size distribution may be explained in terms of spatial rearrangement of the particles, and an apparent dilution effect. The results obtained in this study indicate that...

Preparation of Poly(vinyl chloride) Latexes Using a Dual Surfactant System: The Effect in the Particle Size Distribution

Tomás, A.; Gil, M. H.; Bordado, J. C.; Gonçalves, P.; Rodrigues, P.
Fonte: Wiley Periodicals, Inc Publicador: Wiley Periodicals, Inc
Tipo: Artigo de Revista Científica
ENG
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The control of the average particle size and size distribution in the emulsion polymerization of vinyl chloride monomer is an important parameter to determine, not only the latex characteristics, but also the properties of the final dispersion powder in several industrial applications. It is possible to manipulate the particle size distribution (PSD) by applying a mixture of an anionic surfactant-fatty alcohol before the start of the free radical polymerization. Contrary to the procedures of the miniemulsion and the derivative diffusional swelling techniques, no kind of high shear is applied to the monomer and/or surfactant mixtures. In fact, the concentration and selection of the anionic surfactant, together with the fatty-alcohol, can play an interesting role on the final PSD of the polymer's particles; FCT; contract grant number SFRH/BDE/15534/2005

Young's modulus of Al/SiC P/MgAl2O4 composites with different particle size distribution of reinforcements

Montoya-Dávila,M.; Pech-Canul,M.I.; Escalera-Lozano,R.; Pech-Canul,M.A.
Fonte: Rede Latino-Americana de Materiais Publicador: Rede Latino-Americana de Materiais
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/01/2010 EN
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The effect of particle size distribution of SiC particulate reinforcements coated with colloidal SiO2 on Young´s modulus of Al/SiCp/MgAl2O4 composites fabricated by reactive infiltration was investigated. Composites were prepared from porous preforms of silica-coated α- SiC powders of 10, 54, 86, and 146 μm, 0.6 volume fraction of reinforcements and particle size distribution from monomodal to cuatrimodal. Infiltration tests with the alloy Al-13.3Mg-1.8Si (wt. %) were carried out in Ar→N2 atmosphere at 1100ºC for 60 min. The composites were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). In addition to density and residual porosity measurements, Young´s modulus was evaluated by ultrasonic techniques. Results show that with increase in particles size distribution, residual porosity decreases and density and Young´s modulus of the composites are improved, the latter from 185.39 ±3.6 to 201.93 ±2.3 GPa. This is attributed to the increased metal-ceramic interfaces and to an enhanced matrix-reinforcement load transmission.

Estudio del tamaño de las partículas en suspensión en relación con el caudal y la concentración de sedimento en una cuenca de montaña; Study of suspended particle size in relation with discharge and sediment concentration in a mountain catchment

Gallart Gallego, Francesc; Regüés, D.; Soler, M.
Fonte: Asociación Española para el Estudio del Cuaternario; Sociedad Española de Geomorfología Publicador: Asociación Española para el Estudio del Cuaternario; Sociedad Española de Geomorfología
Tipo: Artículo Formato: 184524 bytes; application/pdf
SPA
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[ES] Se presentan los resultados del muestreo automático del sedimento transportado en suspensión en tres estaciones de aforo instaladas en las cuencas experimentales de Vallcebre (Pirineo Oriental). Este trabajo analiza el tamaño de las partículas de sedimento recogidas por los muestreadores en tres de las estaciones del año (primavera, verano y otoño). Las máximas concentraciones de sedimento observadas han llegado a superar los 100 g l- 1. Los sedimentos transportados son mayoritariamente limo fino, con porcentajes bajos de arcilla y muy bajos de arena fina. Se han encontrado correlaciones positivas entre el tamaño de las partículas y el caudal en los respectivos aforadores mientras que la relación entre el tamaño de las partículas y la concentración de sedimentos sólo es significativa en la cuenca principal. En esta zona de cabecera, la fuente del material de origen es la que determina el tamaño de las partículas transportadas, aunque los procesos de transporte, sedimentación y re-erosión producen su desgaste y fraccionamiento.; [EN] This study shows presents the dynamics of suspended sediment transport at the the results of suspended sediment sampling at three gauging stations in the Vallcebre experimental basins (Eastern Pyrenees). The paper analyses particle size distribution of the automatically collected sediment samples during three seasons: The work analyses particle size characteristics of sediments collected by three automatic samplers in different seasons (spring...

Modeling a fluidized-bed reactor for the catalytic polimerization of ethylene: particle size distribution effects

Grosso,W. E.; Chiovetta,M. G.
Fonte: Latin American applied research Publicador: Latin American applied research
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/01/2005 EN
Relevância na Pesquisa
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Particle size distributions in the output stream of commercial, fluidized-bed reactors for ethylene polymerization are analyzed using a mathematical model. The impact on the overall reactor performance of the universe of sizes for the particles in the bed, with only a fraction of them being extracted in the product flow, is studied. For the output stream, product size distribution is modeled using both triangular and generalized gamma functions. Extraction system parameters are employed to model the particle quantity and sizes. The importance of the proper modeling of the extraction system is shown through the analysis of the effects several output schemes have on the particle size distribution inside the fluidized-bed. Some of the main reactor variables, such as yield and temperature, are studied for several distributions. Operating variables, such as catalyst feed rate, are varied according to the reactor capacity in a typical, 12 meter bed, 130,000 ton/year reactor. Predictions indicate higher output rates for higher catalyst loads, as expected. A shift towards smaller particle sizes in the product and in the bed is observed when increasing catalyst load. Bed fluidization and heat exchange conditions are shown as affected by size distributions. Results show that it is appropriate to include both product and bed particle diameter distribution when studying the reactor performance.

Estimation of the particle size distribution of a dilute latex from combined elastic and dynamic light scattering measurements: A method based on neural networks

Stegmayer,G.S.; Gonzalez,V.D.; Gugliotta,L.M.; Chiotti,O.A.; Vega,J.R.
Fonte: Latin American applied research Publicador: Latin American applied research
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/07/2009 EN
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95.88%
A method for estimating the particle size distribution (PSD) of a dilute latex from light scattering measurements is presented. The method utilizes a general regression neural network (GRNN), that estimates the PSD from 2 independent sets of measurements carried out at several angles: (i) light intensity measurements, by elastic light scattering (ELS); and (ii) average diameters measurements, by dynamic light scattering. The GRNN was trained with measurements simulated on the basis of typical asymmetric PSDs (unimodal normal-logarithmic distributions of variable mean diameters and variances). First, the ability of the method was tested on the basis of two synthetic examples. Then, the obtained GRNN was used for estimating the PSD of a narrow polystyrene (PS) latex standard of nominal diameter 111 nm. The standard was also characterized by 2 independent techniques: capillary hydrodynamic fractionation, and transmission electron microscopy (TEM). The PSD predicted by the GRNN resulted close to that obtained by TEM. The estimated PSDs were better than those obtained through standard numerical techniques for 'ill-conditioned' inverse problems.

Maximizing haematite recovery within a fine and wide particle-size distribution using wet high-intensity magnetic separation

Dworzanowski,M
Fonte: Journal of the Southern African Institute of Mining and Metallurgy Publicador: Journal of the Southern African Institute of Mining and Metallurgy
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/07/2014 EN
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The physical beneficiation of iron ore that has a wide particle-size distribution is problematic, regardless of the process applied, whether dense medium separation, gravity concentration, magnetic separation, or flotation. The problem of particle size is further compounded when there is a significant -10 µm fraction. Generally the approach to a wide particle-size distribution is to split into narrower size ranges and treat each separately. More often than not the -10 µm fraction is not treated but discarded. This approach results in a more complicated and expensive flow sheet and the loss of any potential value in the -10 µm fraction. Wet high-intensity magnetic separation (WHIMS) bench-scale test work was conducted on a haematite-rich material with a particle size of -200 µm What made this material different was that it contained a 60% -10 µm fraction, hence discarding the -10 µm material was not an option. The objective of the test work was to determine how to maximize the recovery of the haematite across the full particle size range. Given the unusual particle size distribution, it was concluded that WHIMS would be the only practical beneficiation route. The -200 +10 µm and -10 µm fractions were treated separately and together under varying WHIMS conditions. For a given concentrate grade...

Relationship between particle size and manufacturing processing and sintered characteristics of iron powders

Sánchez,F.; Bolarín,A. M.; Molera,P.; Mendoza,J. E.; Ocampo,M.
Fonte: Universidad Simón Bolívar; ; Publicador: Universidad Simón Bolívar; ;
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/01/2003 EN
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Abstract The effect of particle size distribution on physical properties of powder mixtures, of green compacts and of sintered samples has been studied. In the case of powder mixtures, the evaluated properties were flowability, apparent density, specific surface and compressibility. In green compacts porosity, roughness and green strength were evaluated, and in sintered samples grain size and transverse rupture strength were measured. In order to obtain samples with different average particle size, water atomized iron powders were sieved and separating it with sieves ranging from +44 to -150 m m. Flowability and compressibility decrease as average particle size does. On the opposite side, green strength and transverse rupture strength (TRS) increase as particle size diminishes. These effects were associated with changes in morphology and specific surface of the studied powder mixtures. Mathematical expressions relating average particle size with green strength, roughness and ultimate tensile strength were deduced from the experimental results. The results show that an appropriate selection of average particle size for the preparation of the powder mixture is useful in order to obtain samples with suitable physical properties.