Showing papers in "Powder Technology in 1996"

TL;DR: In this paper, the porosity of mono-sized particles is strongly dependent on both particle shape and packing method, and for a given packing method can be approximately by the proper use of the packing results of cylinders and disks.

TL;DR: In this paper, the formation of titania powders by oxidation of TiCl4 was studied in a laminar diffusion flame reactor, where the effects of flame configuration (fuel and oxidant flow rate and position) as well as precursor TiCl 4 loading on the specific surface area and phase composition of the product titania powder were investigated.

TL;DR: Granule consolidation during tumbling was found to be a complex process controlled by the balance between the different mechanisms that resist granule deformation: interparticle friction and viscous dissipation as discussed by the authors.

TL;DR: A review of recent progress on particle formation in gases for synthesis of materials is given focus in the session Particle Formation in Gases at the First International Forum on Particle Technology held in Denver, CO, in August 1994 as mentioned in this paper.

TL;DR: In this article, a non-intrusive probe of the average kinetic energy, or granular temperature, of the particles at the wall of a gas fluidized bed is presented.

TL;DR: In this article, the structural inhomogeneity of alumina specimens, compressed in a top pressed cylindrical die, is studied experimentally, by using lead balls as tracers to detect the densification, as well as by numerical computation.

TL;DR: In this paper, the influence of the pressure drop across the air distributor on the bubbling conditions of the bottom bed of circulating fluidized beds (CFB) was studied, and the results indicated that the boiler always operates in the single or exploding bubble regime, indicating a bubble flow that is not continuous and not well distributed over the crosssection of the bed.

TL;DR: Flowability can best be described by using the flow function as being the relationship between the unconfined yield strength and the major principal stress at steady state flow as mentioned in this paper. But exact measurement of flow function is possible only with testers, and expensive regarding time and equipment.

TL;DR: In this article, the most significant advantages, disadvantages and pitfalls of pneumatic conveying technology are summarized, and a discussion of the development of prediction procedures for pressure drop and state of flow is used to show the development in the technology itself.

TL;DR: In this article, the authors investigated the influence of three operating parameters on the comminution of limestone in a stirred media mill: the circumferential velocity of the stirrer discs, the density and the size of the grinding beads.

TL;DR: In this article, a predictive mathematical model is proposed to characterize and quantify all facets of the time-averaged gas and solids flow structure and properties within circulating fluidized bed (CFB) risers.

TL;DR: In this paper, a non-linear force formula for discrete element simulations with the particles separating when the force returns to zero rather than when the distance between the centres exceeds the sum of the radii is found to give realistic results.

TL;DR: In this article, a micromechanical model of powder compaction is proposed which leads to an explicit form of the Kawakita relationship for particles which deform plastically, rather than fracture, the compaction behaviour may be described by a reduced form of this explicit relationship.

TL;DR: In this paper, an optical measuring system based on detection of light reflected by the suspended particles was developed to measure local solids concentration and local axial solids velocity in dense gas-solid two-phase flows.

TL;DR: In this paper, a qualitative model for the fluidization characteristics of cohesive iron particles was developed focusing on the mechanism of defluidization and the particle-to-particle neck growth.

TL;DR: In this paper, the flow field, the distribution of specific energy and the motion of single grinding beads in the grinding chamber of a stirred media mill have been calculated based on steady-state laminar stirring of a Newtonian fluid without grinding media.

TL;DR: In this article, two kinds of particles, typifying those from group A and group B, were employed in the experiments to determine the boundaries between the flow regimes of gas-solids fluidization.

TL;DR: In this article, the effect of the field line orientation on the behavior of gas fluidized beds has been investigated using different, non-cohesive ferromagnetic powders in the absence of a magnetic field.

TL;DR: In this paper, the authors define a method to show the characteristics and origins of defects and other structural features that are detrimental to the properties of ceramics, such as large pores, large particles, large aggregates and particle orientation.

TL;DR: In this paper, a theoretical and experimental study of the conveying speed with which granular materials are transported by vibratory conveyors is made, where the basic assumption made is that the layer of granular material can be considered as a point mass.

TL;DR: In this paper, electrical resistance tomography (ERT) is used for three-dimensional imaging of the concentration of solids in a slurry mixer as a function of key process variables (particle size, impeller type, agitation speed).

TL;DR: In this article, the fluidization behavior of Geldart's group C powders has been studied and the experiments demonstrate that channels and bubbles can be eliminated effectively by forming a chain structure.

TL;DR: The scale-up and commercialization of any chemical process is an inexact science and the scaleup of fluidized bed processes is especially so as discussed by the authors, and the problem of gas bypassing and poor contact with bed particles has been recognized as a major scaling consideration for a generation.

TL;DR: The surface properties of talc, calcite, dolomite, silica and zirconia, untreated and as ground powders, were determined by contact angle measurements (directly on flat surfaces and by thin layer wicking for powders).

TL;DR: In this article, the authors measured local heat transfer to membrane walls of a circulating fluidized bed (CFB) boiler for three sizes of the same silica sand, with mean diameters of 0.22, 0.34 and 0.44 mm.

TL;DR: In this paper, the rheological behavior 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.

TL;DR: The modelling of agglomerating systems is demonstrated by focusing on processes where liquid binder provides the dominant adhesion force between particles, and recent advances in the concepts of fractal analysis to provide quantitative information on the openness of Agglomerate structures are described.

TL;DR: In this paper, image analysis is used to determine the mean, mode, standard deviation, variance, and skewness of local composition for a large number of locations in the mixtures, providing an effective method for performing a detailed quantitative characterization of the mixture structure.

TL;DR: In this article, the attrition data of calcium oxide pellets in a circulating fluidized bed absorber (CFBA) were presented with a modified second-order attrition model incorporating an asymptotic minimum bed weight and an excess gas velocity from the minimum fluidization.

TL;DR: In this paper, the degree of liquid saturation of the agglomerates and the growth rate is determined by the amount of binder liquid and the particle packing density, which can be applied in the analysis of mixer scale and processing conditions on liquid requirements and the final granule size.