Validation of a discrete element method (DEM) model of the grinding media dynamics within an attritor mill using positron emission particle tracking (PEPT) measurements

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Validation of a discrete element method (DEM) model of the grinding media dynamics within an attritor mill using positron emission particle tracking (PEPT) measurements. / Daraio, Domenico; Villoria, Jose; Ingram, Andrew; Alexiadis, Alessio; Stitt, E. Hugh; Marigo, Michele.

In: Applied Sciences (Switzerland), Vol. 9, No. 22, 4816, 01.11.2019.

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@article{549a7a91ee3d4525ac83b7ab486469db,
title = "Validation of a discrete element method (DEM) model of the grinding media dynamics within an attritor mill using positron emission particle tracking (PEPT) measurements",
abstract = "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%.",
keywords = "Coarse graining, Discrete element method (DEM) simulations, Grinding media motion, Positron emission particle tracking (PEPT), Validation, Vertical stirred mill",
author = "Domenico Daraio and Jose Villoria and Andrew Ingram and Alessio Alexiadis and Stitt, {E. Hugh} and Michele Marigo",
year = "2019",
month = nov,
day = "1",
doi = "10.3390/app9224816",
language = "English",
volume = "9",
journal = "Applied Sciences",
issn = "2076-3417",
publisher = "MDPI",
number = "22",

}

RIS

TY - JOUR

T1 - Validation of a discrete element method (DEM) model of the grinding media dynamics within an attritor mill using positron emission particle tracking (PEPT) measurements

AU - Daraio, Domenico

AU - Villoria, Jose

AU - Ingram, Andrew

AU - Alexiadis, Alessio

AU - Stitt, E. Hugh

AU - Marigo, Michele

PY - 2019/11/1

Y1 - 2019/11/1

N2 - 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%.

AB - 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%.

KW - Coarse graining

KW - Discrete element method (DEM) simulations

KW - Grinding media motion

KW - Positron emission particle tracking (PEPT)

KW - Validation

KW - Vertical stirred mill

UR - http://www.scopus.com/inward/record.url?scp=85075248717&partnerID=8YFLogxK

U2 - 10.3390/app9224816

DO - 10.3390/app9224816

M3 - Article

AN - SCOPUS:85075248717

VL - 9

JO - Applied Sciences

JF - Applied Sciences

SN - 2076-3417

IS - 22

M1 - 4816

ER -