Investigating grinding media dynamics inside a vertical stirred mill using the discrete element method: Effect of impeller arm length

Daraio, Domenico; Villoria, Jose; Ingram, Andrew; Alexiadis, Alessio; Stitt, E. Hugh; Marigo, Michele

doi:10.1016/j.powtec.2019.09.038

Cited by 26 publications

(13 citation statements)

References 57 publications

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“…The remarkable characteristic of energy transmission of particle flow is particle wear and breakage. In the granular flow, the energy dissipation of each part of the particle flow can be characterized by the work done by the internal contact force [12]. c E , f E , and r E represent the energy dissipation as a result of damping force, Coulomb friction force and rolling friction force respectively, which are written by: ( ) )…”

Section: Energy Dissipationmentioning

confidence: 99%

Study on energy transition of dense particulate flow in a horizontal agitator

Zhu

2022

J. Phys.: Conf. Ser.

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Hammer mill cuttings cleaner is an efficient low-temperature drying cuttings equipment. In order to investigate the main components of energy dissipation and the flow characteristics of granular flow in grinding systems. The energy dissipation model of dense particle flow is established by numerical simulation and validated by macroscopic experiment. The results show that the particle flow mainly moves in a circle along the wall of cylindrical vessel. The main parts of energy dissipation are sliding friction consumption of particle, the inelastic collision between particles and sliding friction between particles and container; the input energy is a linear function of particle filling rate. The flat blade can provide higher efficiency at the same operational conditions. The study lays a theoretical foundation for the industrial application of Thermal-mechanical cuttings cleaner of drill cuttings and provides a reference for the optimization of blade configuration.

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Section: Energy Dissipationmentioning

confidence: 99%

Study on energy transition of dense particulate flow in a horizontal agitator

Zhu

2022

J. Phys.: Conf. Ser.

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“…The commercial coarse-graining (CG) software Iota®(Particle-Analytics, Edinburgh, UK) was used for the visualisation of DEM results and the calculation of continuum fields of media properties such as solid fraction and velocity, by averaging the discrete DEM information calculated over the entire simulation time. This software has already been used by the author of this paper to comprehensively investigate the grinding media dynamics inside a vertical stirred mill [24]. The main advantage of the coarse-graining is the ability to handle the large amount of discrete data generated by DEM simulations to represent, starting from microscopic quantities, the continuum bulk properties of the granular material and its flow.…”

Section: Dem and Simulation Conditionsmentioning

confidence: 99%

“…In the last decades, the number of publications using DEM simulations to address granular engineering problems, such as granular flow [13], powder mixing [14][15][16], powder mechanics [17] and milling [18][19][20][21][22][23], has vastly increased. Although the DEM approach to milling still has limitations due to the computational costs of modelling the small particle size of the feed material, the simulations have been useful to drive the mill optimisation as function of operating conditions, to predict the effect of the mill design on the media motion and to support the transition from the lab scale to the industrial scale [24][25][26][27][28][29].…”

Section: Introductionmentioning

confidence: 99%

Validation of a Discrete Element Method (DEM) Model of the Grinding Media Dynamics within an Attritor Mill Using Positron Emission Particle Tracking (PEPT) Measurements

et al. 2019

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Positron emission particle tracking (PEPT) was used to investigate the grinding media dynamics in a laboratory-scale attritor mill in the absence of powder. The grinding media motion was analysed as a function of the equipment’s typical operating parameters: impeller speed, impeller clearance and bead fill level. It was observed that the impeller speed had the strongest influence on the media motion. An increase of the impeller speed from 300 rpm to 600 rpm led to a change in the bead recirculation patterns with the increasing formation of well segregated upper and lower recirculation loops that fully developed at the maximum speed of 600 rpm. For a constant impeller speed, an increase of the bead loading did not majorly affect the bead velocity as remarked by minor changes on the flow field. For all the impeller clearance values, the occupancy plots revealed an inefficient dead region at the bottom of the attritor where the beads were moving at very low velocity. In this region the beads were tightly packed under their own weight and, furthermore, there was an absence of direct contact with the impeller arms. The depth of this region increased proportionally to the distance between the bottom of the impeller and the vessel base indicating that a minimum value of clearance should be set to optimise the lower recirculation pattern. For two experimental conditions, the data generated by PEPT measurements were utilised to set-up a friction-adjusted discrete element method (DEM) model. Here, the simulation results were qualitatively and quantitatively compared against the PEPT data by assessing the averaged velocity flow fields and the average velocity profiles at different radial locations inside the vessel. Given the intrinsic uncertainty of the PEPT measurements, the DEM model results were in considerably good agreement with the experimental results. The major discrepancy was observed close to the vessel wall where the simulations overpredicted the velocity by about 10%.

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“…Particle size fragmentation in horizontal stirred mills typically proceeds by shearing mechanisms. Although the energy transference efficiency of stirred mills is in some cases questioned [5], they remain widely used, in particular for ultra-fine grinding (below 10 µm) [3].…”

Section: Introductionmentioning

confidence: 99%

“…The movement and collision of the grinding media is of paramount interest, helping to evaluate the energy transfer to the product and the residence time. Both quantities may be measured experimentally by introducing solid and liquid tracers to investigate slurry transport and particle breakage [5,8,9]. In parallel to experimental methods, Discrete Element Method (DEM) simulations have been employed to track grinding media trajectories and collisions, and to evaluate the charge behaviour, torque and power draw for dry mills with different designs and at different scales [10,11].…”

Section: Introductionmentioning

confidence: 99%