Showing papers in "Powder Technology in 1985"

TL;DR: The performance of the gas distributor often determines the success or failure of a fluidized bed and although much more is known now than 20 years ago, there are still many pitfalls for the designer.

TL;DR: Aerogel powders, particles of the group C according to the Geldart classification, are not particularly attractive as such for fluidized bed applications as discussed by the authors, however, these fine solids form agglomerates above a minimum superficial velocity of 0.04 m/s and that the resulting new system fluidizes smoothly and homogeneously at room and at higher temperatures.

TL;DR: In this article, a general theory of particle motion was developed in order to understand mixing and segregation in failure zones, which can be applied to systems of low concentrations of small particles, employing previously obtained data on inter-particle percolation rates.

TL;DR: In this article, the tensile strength of fine polydisperse powders is investigated by measuring the diametrical compression test and the stress-strain relationship of samples exposed to uniaxial compression.

TL;DR: In this article, the authors studied granulation in a Fielder ® PMAT 25 VG laboratory-scale mixer by recording power consumption and temperature increase during addition of the binder liquid and found that the consumed energy is converted completely into heat in the moist mass.

TL;DR: In this paper, the tensile strength and packing density of powder compacts containing submicron particles were derived using Hamaker's expression for the van der Waals force and the law of corresponding states, which is used to evaluate an energy parameter ϵ o for a given powder on an absolute scale.

TL;DR: In this article, the effect of compaction pressure on tablet surface area, obtained using both a gas adsorption method and a permeametry technique, was studied for tablets.

TL;DR: In this paper, a half-column incorporating auxiliary flow, introduced through up to five slots along a 60° conical base, in addition to a central flow of air, was investigated.

TL;DR: In this paper, the effects of impeller rotation speed, liquid flow rate and liquid amount upon power consumption and granule growth are investigated by granulation in a Fielder ® PMAT 25 VG high-speed mixer.

TL;DR: In this paper, in-bin segregation, flow pattern and discharge segregation of ternary mixtures of ore and coke were described in a model Paul Wurth hopper, where measuring techniques used include heap freezing, tracer addition, contour mapping and screen analyses.

TL;DR: In this article, the authors compared the stress-strain relationship of granule growth by coalescence with a high-speed mixer and showed that the growth rate is improved by an improved deformability of the moist agglomerates.

TL;DR: In this article, the authors investigated the relation between the co-ordination numbers and the size distributions of randomly packed beds of spheres with log-normal, log-uniform, Rosin-Rammler and Andreasen (Gaudin-Schuhmann) size distributions.

TL;DR: In this article, a tube-in-basket (TiB) burner was used to burn rice husk in a controlled manner to produce amorphous silica powder of high surface area, characterized by X-ray and BET analyses.

TL;DR: In this paper, a mathematical model of the magnetically stabilized fluidized bed, based on the arrangement of particles following field lines, is proposed, which can be applied not only to the fluidization of magnetizable materials but also to non-magnetizable particles.

TL;DR: In this paper, the authors examined some of the difficulties encountered with such correlations when attempting to describe the particle size distribution by Gaussian measures, and developed a new method of expression, by a single "offset" value, of a component size distribution.

TL;DR: In this paper, a detailed study of the sieving kinetics of sinter particles (4-05 mm) is described using a batch sieving technique with continuous weighing of the undersize stream.

TL;DR: In this article, large sand particles with a 1 mm mean diameter were fluidized in large beds with different widths to determine the effect of wall spacing on bed hydrodynamics.

TL;DR: In this article, a study of the relative magnitudes of particle shape effects on three bulk solids properties was made, including apparent density, flow rate and Hausner Ratio.

TL;DR: In this paper, a batch wet grinding of 20 × 30 mesh feeds of quartz and copper ore in a laboratory ball mill gave first-order or non-first breakage of this size depending on conditions, with acceleration of breakage rate occurring for lower slurry density and deceleration at higher.

TL;DR: Les variations of the fraction volumique de particules de syme´trie sphe´rique ou axiale, dans des empilements au hasard, sonte´tudie´es en fonction du rapport, l/d, longueura`diame`tre des particules.

TL;DR: In this paper, the surface area of all tabletted materials increased approximately linearly within the whole pressure range and a more marked increase was obtained for the materials consolidating to a large extent by fragmentation (sodium citrate and lactose).

TL;DR: In this paper, the void fraction in a three-component randomly packed bed was calculated from the authors' model, and the calculated values were compared with published experimental data for spherical and irregularly shaped particles and with results from computer simulations.

TL;DR: In this article, it was shown theoretically and experimentally that under conditions which in most cases are fulfilled, the Kawakita equation represents a good overall approximation if zero-pressure data (i.e. after ejection) are used.

TL;DR: In this article, the authors present analytical solutions to the fragmentation equation for specific rates of breakage and primary breakage distribution functions often used to correlate comminution data, and suggest that correlation of data via similarity techniques may facilitate determination of function parameters.

TL;DR: In this paper, the theory of the size distribution of the equilibrium mixture of balls in a ball mill is developed and the differential equation is solved for wear laws of the form wear rate per ball ∝ r2 + Δ where r is ball radius.

TL;DR: In this article, it was shown that long-term increases in the crushing strength of sodium chloride compacts take place as a result of extensive recrystallization occurring between particle faces, "welding" the particles together.

TL;DR: In this article, the gas continuity equation for a bubbling fluidized bed is derived for the case of low Reynolds number flow in the dense phase, and the results approach those of Davidson's isolated bubble model; however, the visible bubble flow rate is much smaller than that predicted by Davidson's model.

TL;DR: In this article, a simple statistical geometric model was used to calculate porosities and permeability diagrams for three-component mixtures of spheres from only the relative sizes of the spheres.

TL;DR: In this paper, the authors used the power spectral density function and the standard deviation of the pressure fluctuations to accurately determine the choking transition in the dilute phase flow and dense phase flow regimes of vertical pneumatic conveying systems.

TL;DR: In this paper, a new system for circulating fluidized particles within a single vessel has been developed which has the same advantages as the dual-bed systems widely used for the FCC process and the Fluid Coker process.