Free-flowing Material Research Articles

МЕХАНИКА ИЗМЕЛЬЧЕНИЯ ПРОКАТЫВАЕМЫХ В ТОЛСТОМ СЛОЕ МАТЕРИАЛОВ

Powder rolling conditions are systematized with the purpose of their compacting and milling. The generalized condition of solid and free-flowing bulk material deformation is proposed in the paper. The analytical solution of a stressed state of powder being shaped mechanically that ensures milling of its particles has been obtained.

Comparative study of the mixing of free-flowing particles in a V-blender and a bin-blender

The objective of this work consists of investigating the influence of process parameters such as the fill level (35, 50 and 65%v/v), loading profile (front–back (FB), right–left (RL) and top–bottom (TB)) and rotational speed (15, 30 and 45 RPM) on the mixing performance of a V-blender and a bin-blender, on the basis of RSD curves, granular mixing dynamics, mean granular velocities and granular temperatures. The mixing systems consisted of two 7.5-L lab-scale versions of industrial V-blenders and conical bin-blenders. Spheronized microcrystalline cellulose granules ( φ = 500 μ m ) were used as free-flowing material. Experimental data were generated by analyzing the concentration of thief samples obtained using core samplers by means of image analysis. As a complement to the experimental work and in order to gain more insight into the flow behavior and mixing dynamics in both blenders, numerical simulations of the flow up to 780 000 monodisperse particles were carried out using the discrete element method (DEM). This study shows in particular that, on the basis of RSD curves, the mixing performance of the bin-blender is comparable to that of the V-blender for FB and TB loading profiles, and that the V-blender clearly outperforms the bin-blender in the case of the RL loading profile.

Kinetics of microwave drying of a free-flowing organic material

The kinetics of drying of a dense buckwheat layer in a microwave electromagnetic field of frequency 2.45 GHz has been investigated for different amounts of the material charged into a working chamber. Analysis of the kinetics curves has shown that the drying of the material studied is divided into the periods of heating, drying with a constant rate, and drying with a decreasing rate. The influence of the power supplied as well as the mass and dimensions of a sample on the rate of its drying has been investigated and a formula for calculating this rate has been obtained. It has been established that, in the process of drying of a disperse material, the amount of microwave energy converted into heat energy depends not only on the mass of a sample, but also on the thickness and area of its surface layer. Generalized equations for calculating the moisture content in a layer of a free-flowing material and its temperature have been obtained.

Quantitative characterization of mixing of free-flowing granular material in tote (bin)-blenders

Experiments were conducted to determine the effects of fill level, mixing time, and use of baffles on the mixing performance of a pilot plant scale tote (bin)-blender. The binary mixture under study was free-flowing, noncohesive art sand of two colors. Mixture uniformity was evaluated by sampling the blend using core samplers with the samples quantified by image analysis. The rate of mixing was significantly affected by the degree of blender fill. Four fill levels were examined, 20% fill (fastest), 40% fill, 60% fill (optimum), and 80% fill (slowest). Top–bottom and side–side initial loading patterns were studied to determine the influence of the axial and radial mixing mechanisms with and without an internal baffle at the manufacturer's standard position. Axial mixing was found to be the rate-limiting step to achieving overall blend homogeneity. The standard baffle configuration only generated moderate enhancements in mixing. A first-order mixing model was applied to determine the mixing rate constant for the various fill levels and baffle conditions investigated.

Large irreversible local slips of a loose free-flowing material under hard sign-variable quasistationary loading

The theory of slip for the case of large strains is considered. Irreversible distortion by slippage is represented as a Truesdell transformation of simple shear and is specified with respect to the unstrained configuration. It is proved that a small local slip leads decreases tangential stresses on the slip area and changes the strained stress over the entire region. The calculated orientations of the local slip systems are compared to results of classical experiments on sign–variable quasistationary deformation of loose free–flowing materials.

An integrated fine coal preparation technology: the GranuFlow Process

In order to alleviate the problems of fine coal handling and processing and to enhance the utilization of fines by utilities, US Department of Energy's (DOE's) Federal Energy Technology Center (FETC) developed and patented the GranuFlow Process. This paper summarizes recent test results of the GranuFlow Process with pilot-scale and plant-scale centrifuges in commercial plants. The main benefits of the GranuFlow Process are that it can potentially reduce the amount of waste coal that is stored in refuse impoundments, reduce the moisture content of the final clean coal product, improve handling by converting wet sticky fines to a granular, free-flowing material, prevent frozen coal problems in rail cars, and reduce the dustiness and fugitive dust losses during transportation and handling. Since Orimulsion is a low cost bitumen emulsion, this technology provides the coal industry with a cost-effective technology for fine coal processing.

Vibration action on flowing medium during its discharge from a reservoir

Vibrational end discharge of free-flowing material is considered. Principles permitting significant expansion of the flow zone and more complete use of the reservoir volume are established.

Flow control during discharge of free-flowing material using inclined splitters

Results are presented for studying regularities of the mutual position of splitters that provide multiple division of the flow. Their effect on the discharge velocities for free-flowing material is considered. The problem is stated on controlling the overall shape of the discharged material that forms at the confluence of flows and for ore extraction from under caved rocks within stopes of different configuration with minimum losses and impoverishment.

Numerical modeling of the magnitude of the load on a mass of free-flowing material subjected to the action of a gaseodynamic source

Numerical modeling of the magnitude of the load on a mass of free-flowing material subjected to the action of a gaseodynamic source

Development of a containment cavity in a layer of free-flowing material in gaseodynamic outburst from a subsurface gas source

Development of a containment cavity in a layer of free-flowing material in gaseodynamic outburst from a subsurface gas source

96/04446 Predicting the effects of changes in thermal envelope characteristics on energy comsumption: Application and verification of a simple model for Australlan and Canadian climates

In order to alleviate the problems of fine coal handling and processing and to enhance the utilization of fines by utilities, US Department of Energy's (DOE's) Federal Energy Technology Center (FETC) developed and patented the GranuFlow Process. This paper summarizes recent test results of the GranuFlow Process with pilot-scale and plant-scale centrifuges in commercial plants. The main benefits of the GranuFlow Process are that it can potentially reduce the amount of waste coal that is stored in refuse impoundments, reduce the moisture content of the final clean coal product, improve handling by converting wet sticky fines to a granular, free-flowing material, prevent frozen coal problems in rail cars, and reduce the dustiness and fugitive dust losses during transportation and handling. Since Orimulsion is a low cost bitumen emulsion, this technology provides the coal industry with a cost-effective technology for fine coal processing.

Catastrophic consequences of prolonged weak action on free-flowing material

Prolonged weak action on free-flowing material leads to gradual accumulation in it of irreversible changes and it may lead to loss of stability.

Experimental investigation of the motion of bodies in a fluidized bed

We present experimentally determined characteristics of a gas-fluidized-bed of sand with average grain size and height to diameter ratio of the bed equal to 4.5. We determine the dependence of the resistance of a cylindrical body in a fluidized free-flowing material on the fluidization regime and the conditions of flow around the cylindrical body with body-to-channel diameter ratio equal to 0.15, 0.225, and 0.3

Sluice feeder with conical rotor

The Dimitrovgradkhimmash Works (DW) is now commercially producing feeders SHI and SH2 for feeding free-flowing material at 278 to 373 and 373 to 523 K, respectively*. These feeders suffer from the following vital deficiencies: material spillage through gaps between the inner surface of the body and the surface of the rotor blades which increases as these surfaces wear out in use, and low suitability for repairs as the feeder has to be dismantled and the rotor blades resurfaced and subjected to subsequent mechanical finishing.

Fluidized-Bed agglomeration of acetaminophen; direct compression of tablets and physiologic availability

AbstractA novel process was developed for manufacturing acetaminophen in a free-flowing, directly compressible agglomerated form, involving spray agglomeration of acetaminophen powder with polyvinylpyrrolidone (PVP) in isopropyl alcohol as a bonding agent using a fluidized-bed granulator. Agglomerates prepared with 5% PVP yielded a free-flowing and compressible material. Upon lubrication with 0.5% magnesium stearate, the material was found to be directly compressible into tablets. To improve dissolution and tableting properties, the agglomerates were compressed into tablets after blending with varying weight ratios of microcrystalline cellulose/pregelatinized starch as a filler/disintegrant combination. The final stable tablet formulation consisted of agglomerates equivalent to 325 mg of acetaminophen, 2.1 mg of magnesium stearate, and the filler/disintegrant in a weight ratio of 70:30 to yield a tablet weight of 425 mg. Physical properties and dissolution profile of these tablets were comparable to those...

A model of the process of mixing of a free-flowing material in a transverse section of a revolving barrel

A model of the process of mixing of a free-flowing material in a transverse section of a revolving barrel

Particle Shape Discrimination Using Slotted Sieves

set of sieves having rectangular apertures has been used, with a set of square-mesh sieves, to separate powder particles according to their shape. A free-flowing granular material, sodium perborate tetrahydrate, was shape-sorted using the slotted sieves and also using an inclined, vibrating deck.The length, width, thickness, projected area diameter and equivalent volume diameter were determined for each shape-fraction and these data were used to calculate shape factors to assess the performances of the two methodsIt was found that both methods were capable of sorting the material according to particle shape. The deck was capable of a slightly higher throughput, but the sieves were more selective as well as being quantitative with respect to two of a particle's three principal dimensions.

Selection of equipment for coke processing

This article shows how the design and selection of equipment for the crushing, transportation, and storage of petroleum coke is dependent on the physicomechanical properties of the coke. The mechanical properties of petroleum coke depend on its total porosity, which is determined from true and apparent densities. Topics considered include screen composition, bulk density, the degree of compaction, coefficients of internal and external friction, segregation, and the angle of repose. A vibrating platform operating at 350 cycles per minute was used to investigate the dynamics of compaction of coke fractions during rail transport. It is emphasized that the physical properties of coke as a free-flowing material are of paramount importance in designing the processing and transportation systems and storage facilities for coking and calcining units.

Macromechanism of powder deformation in the incoherent zone during rolling

Observation of the deformation of a free-flowing material through transparent hopper walls is a technique yielding a great deal of useful information and enabling the deformation behavior of powders to be studied in the lag zone (breaks in the velocity field, formation of arch structures, and the like). A binding link between the geometric and physical parameters of the powder rolling process is the initial powder compressibility. An increase in the intensity of the shear deformation of powders before the commencement of their irreversible densification suggests that impeded deformation zones may not be able to form above the angle of rolling.

Automatic stabilization system for introducing free-flowing material into a converter

Automatic stabilization system for introducing free-flowing material into a converter