Showing papers in "Powder Technology in 1989"

TL;DR: In this paper, explicit equations for the drag coefficient and for the terminal velocity of falling spherical and nonspherical particles are developed for the CD and ut. The goodness of fit of these equations to the reported experimental data is evaluated and compared with that of other recently proposed equations.

TL;DR: In this article, the authors make an estimation of the various factors, including geometrical, adsorption, capillary and electrostatic, affecting particle aggregation and conglomeration, and hence their fluidization.

TL;DR: In this article, a detailed evaluation of size, shape and microstrains of BaTiO3 crystallites produced by hydrothermal crystallization at 90 − 180 °C and 0.1 − 1.2 MPa, from amorphous TiO2· xH2O (3 < × < 8) gel and aqueous Ba(OH)2 is presented, using X-ray line-broadening and TEM studies.

TL;DR: In this paper, the settling velocities of spherical particles in viscous non-Newtonian pseudoplastic solutions were measured and the wall effect was investigated by varying the ratio of particle diameter to column diameter in the range of 0.05 to 0.78.

TL;DR: In this article, the authors extended the mechanism of coating of a coarse granular material by a fine cohesive powder in a rocking-type mixer, presented in a previous publication, to the case of mixers with higher mechanical energy input, such as high-speed-stirred mixer and high-shear mill.

TL;DR: In this paper, fine powders of SiC, TiO2 and Ni naturally formed agglomerates in the bed and behaved as Geldart class A particles, and the minimum fluidization velocity was dependent on pressure and was correlated by the equation considering compressibility and Knudsen flow.

TL;DR: In this paper, a series of tests on electrical disintegration of the granite samples, a pulse generator of the Marx type was used, and it was found that the regularity of occurrence of electrical breakdown and the explosion of the lumps has a probabilistic character.

TL;DR: In this paper, the authors measured the residual die wall pressure during compaction of drug powders to elucidate the mechanisms involved in capping, and they found that capping was the fracture of compacted powders caused by high residual diewall pressure.

TL;DR: In this article, a review of the features which allow a good powder to be recognized is presented, and the measurement of these subtle powder parameters, their control and modification, and their effects on the manufacture and properties of advanced ceramic components are discussed in detail.

TL;DR: In this paper, a model of primary fragmentation accounting for anisotropy due to bedding planes is proposed for spherical particles and the starting point for prediction of the occurrence of fragmentation is a simple monoaxial stress field, consisting of internal forces due to volatile pressure opposite to resistance forces of the material.

TL;DR: In this article, the authors investigate the transition between the two states, i.e., coherent-expanded and coherent-condensed (CC) states, in order of increasing bed depth.

TL;DR: In this article, various operating parameters such as stirring speed, pulp density and the use of grinding aids have been studied using a laboratory stirred ball mill, and it has been found that the mill operates most efficiently at low stirring speeds and high pulp densities, as long as the viscosity is controlled within limits.

TL;DR: In this paper, an experimental technique is developed based upon division of the bed into slices before the gas supply is turned off, which is described according to the Gibilaro-Rowe model.

TL;DR: A probability method of conveniently presenting screening data pertaining to a given system, thus representing the overall behaviour of the material without having to quantitatively describe the vibratory motions of the screen and the particles separately is developed.

TL;DR: In this article, a correlation relating drag coefficients for spheroidal particles to Reynolds number and aspect ratio has been developed, which is capable of accurately predicting drag coefficients over a Reynolds number range of 1 to 200 with the aspect ratio varying from 0.2 to 5.

TL;DR: In this article, a dynamic gas tracer system based on a pair of rapid-response mass spectrometers was employed, and the tracer itself was argon delivered in the form of a pulse.

TL;DR: In this paper, the effect of slurry density on the dynamics and grinding behavior of a batch ball mill was studied using quartz as a test material, and it was found that slurry densities determined the distribution of solid charge in the mill, with migration of particles from the tumbling zone to the mill periphery as solid concentration was progressively increased.

TL;DR: In this paper, the effects of air inlet velocity (6 ∼ 17 m/s), particle size (141 ∼ 211 μm), solid loading (0.0 ∼ 0.189 kg/m3) and geometric ratio of cylinder to cone height (1.8 ∼ 5.0) on the hydrodynamic characteristics such as pressure drop, collection efficiency and residence time distribution of solid particles have been determined in three different cyclones.

TL;DR: In this article, a back-transform technique has been presented to yield the bubble size distribution for a given distribution of time intervals when the probe ‘cuts’ a bubble, which is demonstrated for two different bubble size distributions.

TL;DR: The early Eastern European literature on the effects of magnetic fields on fluidized beds of magnetizable particles is reviewed in this article, where other works by Western authors during this period are also included.

TL;DR: In this paper, an experimental technique has been developed which essentially measured the forces between two surfaces as they approach, which is capable of measuring small forces (nN) and small distances (

TL;DR: In this article, a new correlation for friction factor in horizontal pneumatic conveying is proposed, based on the unified theory of Yang, which can predict the saltation point.

TL;DR: In this paper, the results of the analysis were found to be consistent and reproducible, in agreement with those obtained from microscopic examination and from the elution profiles of latex particle standards.

TL;DR: Etude de la vitesse limite de particules lors de la sedimentation en regime de Newton and correlation du coefficient de trainee avec les caracteristiques de forme des particules non spheriques.

TL;DR: In this article, a correction factor was introduced to evaluate the influence of falling particles surrounding a single falling particle on the heat transfer coefficient between the air stream and the single particle, and it was shown that the correction factor is close to unity when the average number of particles falling in rotary dryers and coolers is relatively small.

TL;DR: In this paper, a model based on solid mechanics for predicting the pressure drop was tested and showed good agreement with the experimental data, indicating that the plug stability is affected by many factors such as initial bed length, powder properties and pipe diameter.

TL;DR: In this paper, a kinetic study has been conducted to determine the influence of reagent type on flotation rates of ultrafine coal, including anionic surfactants, surfactant-alcohol mixtures, and frothing alcohols.

TL;DR: In this article, the behavior of cohesive powders in a narrow-diameter fluidized bed is investigated and three powders of a polymeric material ranging in particle size from 12.2 to 19.4 μm were used.

TL;DR: In this paper, a segregation index for vibrated binary mixtures, based on the concentration profile of the fines in a segregation cell, is proposed, which takes into account the overall composition of the mixture and its major parameter is the fines weight fraction at the very bottom and not in the bottom half of the cell.