Showing papers in "Powder Technology in 1974"

TL;DR: In this article, a new method for analytical estimation of the binding force is proposed and the interrelations among various similar methods so far proposed are discussed and the validity of the circular approximation for the meridian curve of the bridge surface is quantitatively examined.

TL;DR: A continuum theory for the flow of granular materials with incompressible granules is described in this article, which is intended to describe the flow at low stress levels where pneumatic effects of the contained gas phase are negligible.

TL;DR: In this paper, the Richardson-Zaki equation was used to determine the settling velocity of two particle fractions in binary sedimentation, where the total particle concentration is used to correct the terminal fall velocity of the particles in each fraction.

TL;DR: In this article, the authors measured changes in pore size distribution during initial stage sintering of compacts of submicron size particles of several oxides, including Magnesia and ferric oxide.

TL;DR: In this article, the influence of operating variables on the mean and variance of the residence time distribution for material transport in a continuous rotary drum is described and an approximate form of the exact solution to the axial dispersion model for an impulse input is provided.

TL;DR: In this paper, the packing of real and model continuous distributions of particle sizes is considered and an extension of an algorithm for the calculation of random densest packing is given which applies to continuous distributions.

TL;DR: In this article, a stochastic theory of flow is presented, which represents the convergent flow of cohesionless particles under gravity toward an open orifice as equivalent to a counterflow of voids from the orifice upward through the bed by biased random flight; the theory is summarized in a new phenomenological form.

TL;DR: In this article, the effects of stirring speed, baffles, solids loading, particle size and bridging liquid concentration on spherical agglomerate growth were investigated using sands, dispersed in agitated carbon tetrachloride and agglated with calcium chloride aqueous solutions.

TL;DR: In this article, the apparent flotation rate distributions have been estimated from the flotation kinetic data by the numerical inversion of the Laplace transform, and the distributions were analyzed for their dependence on aeration rate, particle size and initial pulp density.

TL;DR: In this paper, a linear relation was found between pore volume and log of the applied force, and a linear relationship between bulk volume and pore volumes of the compacts of hydroxyapatite before and after sintering.

TL;DR: In this paper, the tensile strength of lightly consolidated beds of dry small spherical glass beads was measured and the average value of the particle-particle bond was calculated from a model due to Rumpf as being ∼ 1 μN.

TL;DR: In this paper, a simple physical model describing the axial transport of dry particulate solids through horizontal, rotating cylinders has been investigated, and design equations are presented which relate particle hold-up in the cylinder to mass flow rate as a function of the cylinder dimension and speed of rotation.

TL;DR: In this paper, a method of calculating a theoretical cut-off point between intra-and interparticle voids has been derived for powders of uniform size for detecting structural changes arising from the high intrusion pressures.

TL;DR: In this article, the pore size distribution determined by nitrogen desorption isotherm and mercury penetration methods has been reported with low pore volume samples, and large discrepancies in pore sizes distribution and pore volumes were found with high pore volumetric silicas and were shown to be a function of the pORE volume of the silica.

TL;DR: In this article, a new method of determining factors which inhibit the flow of dry particulate solids on inclined surfaces has been developed, based on the fact that material flowing on an inclined surface will accelerate if the net gravitational force on any element is larger than the net resistive force acting on the same element to inhibit flow.

TL;DR: In this paper, a possible state of random packing is formulated as a synthesis of deviations from regular arrangements and on the basis of this postulate the distribution of coordination numbers is estimated definitely as a monovalent function of the porosity value of the packing.

TL;DR: A survey of the pore size distribution in hydrated tricalcium silicate pastes using mercury intrusion porosimetry was made by as discussed by the authors, where the results were interpreted in terms of microstructural features revealed by scanning electron microscopy, and also compared with earlier studies on cement pastes.

TL;DR: In this article, an unsteady solute dispersion technique was used to characterise dispersion in a baffled flotation column and the practicality of the baffle shapes and spacings was tested using a synthetic ore comprised of uniform glass beads made suitably hydrophobic by treatment with silicone oil.

TL;DR: In this paper, a critical comparison between values for the minimum outlet slot width and the minimum hopper wall slope for mass flow predicted by the Jenike method, and values obtained from experiments on a full-scale silo with symmetrical wedge-shaped hopper.

TL;DR: Porosity profiles are determined from stationary flowing granular bulk solids in a silo using gamma ray absorption techniques as discussed by the authors, and the measured porosities were found to be higher than the maximum values observed on a static bed in the minimum fluidisation state.

TL;DR: In this paper, simple graphical procedures for determination of empirical correlations for the variations in selection parameters of the discretized batch grinding equation with the particulate mass and the size of the grinding media balls are described.

TL;DR: In this paper, a simple laboratory method for the preparation and classification of high aspect ratio mica flakes is described, based on the studies of Dye and Haller, and the rates of ultrasonic delamination were investigated in the presence of finely divided silica, calcium carbonate and mica.

TL;DR: In this paper, a model for rod milling is proposed which states that the top sizes present in the distribution are broken preferentially, and the preferential action of the rod mill on larger sizes makes relatively minor changes to the shapes of the size distributions produced.

TL;DR: In this article, a semi-empirical relation is given as a criterion to find out if homogeneous fluidization is possible, and two types of fluidization are possible, homogeneous and heterogeneous, depending on the gas velocity, gas viscosity and the gas solid density difference.

TL;DR: Using a three-phase fluidized bed, the effects of particle sizes and flow rate of both liquid and gas on the bed porosity and diameter of the bubbles were studied in this article.

TL;DR: In this article, an ion exchange mechanism between H aq + in the outer Helmholtz layer and M aq+ in solution is suggested, where the hydrated cation is assumed to be held to a negative surface site by electrostatic forces.

TL;DR: In this paper, some experimental techniques concerning the construction of reproducible homogeneous porous masses are discussed, using a X-ray absorption technique, using some basic assumptions regarding packing formation, a technique is proposed in which the packing is formed by particles falling in a vessel from a certain height and with a certain intensity of deposition, while in the meantime the developing packing is vibrated in a horizontal direction.

TL;DR: In this article, the X-ray absorption technique of particle size analysis for detecting changes in powder concentrations with time and depth in a settling suspension has been extended to a disc centrifuge where acceleration due to the centrifugal field extends the technique to submicrometre powders.

TL;DR: In this paper, the expansion data of Mogan for fine solids fluidized with gas under pressure have been re-examined and a modified Richardson-Zaki relationship was derived involving an “effective” porosity.