Cohesive effects in powder mixing in a tumbling blender

Chaudhuri, Bodhisattwa; Mehrotra, Amit; Muzzio, Fernando J.; Tomassone, M. Silvina

doi:10.1016/j.powtec.2006.04.001

Cited by 145 publications

(88 citation statements)

References 30 publications

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“…The DE method has been widely used to study the flow of granular materials within industrial (e.g. Chaudhuri et al, 2006;Sarkar and Wassgren, 2010) or environmental applications such as avalanche dynamics (e.g. Rognon et al, 2008;Faug et al, 2009).…”

Section: Motivation and Objectivesmentioning

confidence: 99%

Modeling of crack propagation in weak snowpack layers using the discrete element method

Gaume¹,

Herwijnen²,

Chambon

et al. 2015

The Cryosphere

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Abstract. Dry-snow slab avalanches are generally caused by a sequence of fracture processes including (1) failure initiation in a weak snow layer underlying a cohesive slab, (2) crack propagation within the weak layer and (3) tensile fracture through the slab which leads to its detachment. During the past decades, theoretical and experimental work has gradually led to a better understanding of the fracture process in snow involving the collapse of the structure in the weak layer during fracture. This now allows us to better model failure initiation and the onset of crack propagation, i.e., to estimate the critical length required for crack propagation. On the other hand, our understanding of dynamic crack propagation and fracture arrest propensity is still very limited.To shed more light on this issue, we performed numerical propagation saw test (PST) experiments applying the discrete element (DE) method and compared the numerical results with field measurements based on particle tracking. The goal is to investigate the influence of weak layer failure and the mechanical properties of the slab on crack propagation and fracture arrest propensity. Crack propagation speeds and distances before fracture arrest were derived from the DE simulations for different snowpack configurations and mechanical properties. Then, in order to compare the numerical and experimental results, the slab mechanical properties (Young's modulus and strength) which are not measured in the field were derived from density. The simulations nicely reproduced the process of crack propagation observed in field PSTs. Finally, the mechanical processes at play were analyzed in depth which led to suggestions for minimum column length in field PSTs.

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Section: Motivation and Objectivesmentioning

confidence: 99%

Modeling of crack propagation in weak snowpack layers using the discrete element method

Gaume¹,

Herwijnen²,

Chambon

et al. 2015

The Cryosphere

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“…The effect of the operating conditions examined using the mill is listed in Table 1. 3 COMPUTATIONAL METHOD The DEMs, originally developed by Cundall and Strack [13,14], were used to simulate the dynamic behavior of granular materials inside the hammer mill. It has been successfully used to simulate chute fl ow, hopper discharge and fl ows in rotating drums [15][16][17]. In this model, the granular material is considered as a collection of frictional inelastic spherical particles.…”

Section: Experimental Methodsmentioning

confidence: 99%

Experiment and model-based investigation of comminution in a hammer mill

Naik¹,

Feng²,

Chaudhuri³

2014

Int. J. CMEM

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Particle size reduction of dry granular material by mechanical means, also known as milling or comminution, is undoubtedly a very important unit operation in pharmaceutical, agricultural, food, mineral and paper industries. As comminution is a stochastic and a nonlinear process, an attempt was made to understand this complicated process by conducting parametric studies experimentally and computationally using discrete element method (DEM). Greater size reduction was observed at higher rotational speed of the hammer owing to the greater centrifugal force experienced by the particles. Increase in impeller wall tolerance resulted in rolling mode regime of powder bed, which was found to be signifi cant at low impeller speeds. A numerical model based on DEM was used to simulate a hammer mill and study the breakage and kinematics of the particle motion within the hammer mill. In the simulations, increase in hammer tip speed causes higher frequency of impact of particles per unit time and higher specifi c energy of impact resulting in generation of much fi ner end product. A limit can be conceived during the breakage event. This is because as size reduction occurs, the breakage rates can fall for very fi ne particles as crack propagation ceases. This is because as size decreases the probability of fi nding a fl aw also decreases. Simulations also showed a higher milling rate for big hammers as larger hammers decrease the tolerance between the milling chamber and rotating impeller. To study the effect of material properties, the energy of fragmentation was estimated and it was found to increase as the material became more cohesive.

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“…When f is further increased, mixing index sharply decreases but the effect of liquid is quite complex: wet particles have better mixing performance at filling of 64%, at which the mixing index of dry particles has a minimum. The enhanced mixing for cohesive particles has been reported previously [6,17] Based on the suggestions of previous studies [18,19], particle circulation period was adopted to quantify the effect of particle convection, which is the dominant mechanism for transverse mixing. The circulation period T is the number of drum revolutions required for a particle to complete a circulation around the bed.…”

Section: Particle Mixingmentioning

confidence: 99%