Comparison of three rotational shear cell testers: Powder flowability and bulk density

Koynov, Sara; Glasser, Benjamin J.; Muzzio, Fernando J.

doi:10.1016/j.powtec.2015.04.027

Cited by 53 publications

(29 citation statements)

References 36 publications

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“…While results from RST-01 and RST-XS are in good agreement, a considerable deviation (up to 20 %) was observed when comparing results from the Schulze ring shear tester to the Jenike shear tester. Similar outputs are found by other researchers (Berry et al, 2015;Koynov et al, 2015;Salehi et al, 2017), where yield loci from the Brookfield powder flow tester, the Schulze ring shear tester, the FT4 powder rheometer and the Jenike shear tester are compared. The Brookfield powder flow tester and the FT4 powder rheometer show systematically lower shear responses in comparison to the other two shear testers.…”

Section: Introductionsupporting

confidence: 77%

“…Although shear testing technologies have been developed and studied extensively, significant scatter in measurements is still common when testing powder flowability using different devices in different labs/environments (Freeman, 2007;Schulze, 1994;Berry et al, 2015;Schulze, 2001;Kamath et al, 1993;Kamath et al, 1994). Previous studies have been focusing on this problem by performing round-robin experimental studies on the Jenike tester (Akers, 1992), the Schulze ring shear tester (Schulze, 2001) and the Brookfield powder flow tester (Berry et al, 2015) as well as comparing different devices (Koynov et al, 2015). The earliest round-robin study (Akers, 1992) resulted in a certified material (CRM-116 limestone powder) and a common standard experimental testing procedure for determining the yield locus.…”

Section: Introductionmentioning

confidence: 99%

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Effect of Particle Size and Cohesion on Powder Yielding and Flow

Shi

Mohanty

Chakravarty

et al. 2018

KONA

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The bulk properties of powders depend on material characteristics and size of the primary particles. During storage and transportation processes in the powder processing industry, the material undergoes various modes of deformation and stress conditions, e.g., due to compression or shear. In many applications, it is important to know when powders are yielding, i.e. when they start to flow under shear; in other cases it is necessary to know how much stress is needed to keep them flowing. The measurement of powder yield and flow properties is still a challenge and will be addressed in this study. In the framework of the collaborative project T-MAPPP, a large set of shear experiments using different shear devices, namely the Jenike shear tester, the ELE direct shear tester, the Schulze ring shear tester and the FT4 powder rheometer, have been carried out on eight chemically-identical limestone powders of different particle sizes in a wide range of confining stresses. These experiments serve two goals: i) to test the reproducibility/ consistency among different shear devices and testing protocols; ii) to relate the bulk behaviour to microscopic particle properties, focusing on the effect of particle size and thus inter-particle cohesion. The experiments show high repeatability for all shear devices, though some of them show more fluctuations than others. All devices provide consistent results, where the FT4 powder rheometer gives lower yield/steady state stress values, due to a different pre-shearing protocol. As expected, the bulk cohesion decreases with increasing particle size (up to 150 μm), due to the decrease of inter-particle cohesion. The bulk friction, characterized in different ways, is following a similar decreasing trend, whereas the bulk density increases with particle size in this range. Interestingly, for samples with particle sizes larger than 150 μm, the bulk cohesion increases slightly, while the bulk friction increases considerably-presumably due to particle interlocking effects-up to magnitudes comparable to those of the finest powders. Furthermore, removing the fines from the coarse powder samples reduces the bulk cohesion and bulk density, but has a negligible effect on the bulk friction. In addition to providing useful insights into the role of microscopically attractive, van der Waals, gravitational and/or compressive forces for the macroscopic bulk powder flow behaviour, the experimental data provide a robust database of cohesive and frictional fine powders for industrially relevant designs such as silos, as well as for calibration and validation of models and computer simulations.

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Section: Introductionsupporting

confidence: 77%

Section: Introductionmentioning

confidence: 99%

Effect of Particle Size and Cohesion on Powder Yielding and Flow

Shi

Mohanty

Chakravarty

et al. 2018

KONA

View full text Add to dashboard Cite

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“…A comparison study between different direct shear test devices: Jenike translational shear tester (Jenike, 1964), Schulze ring shear tester (Schulze, 2008), FT4 powder rheometer (Freeman, 2007) and Brookfield powder flow tester (Berry et al, 2015), show a deviation between the results, e.g. the Brookfield and the FT4 show a lower shear stress in comparison to the rest of devices (Leturia et al, 2014;Koynov et al, 2015;Shi et al, 2018). Each device has an operational range of normal stress where results are more accurate, e.g.…”

Section: Introductionmentioning

confidence: 99%

Qualitative and quantitative DEM analysis of cohesive granular material behaviour in FT4 shear tester

Louati¹,

Bednarek²,

Martin³

et al. 2019

Chemical Engineering Research and Design

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The macroscopic behaviour of cohesive granular material in the FT4 shear tester is studied using the discrete element method (DEM). The shear test is simulated faithfully to the experimental procedure (filling, compaction, pre-shearing and shearing). The angle of internal friction and the apparent bulk cohesion are the macroscopic properties analysed as a result of the variation of the microscopic parameters: the sliding friction coefficient and the adhesive surface energy. The simplified JKR model was used to account for the cohesive contact between spheres. The results of the shear test show that the adhesive forces influence the dilatancy of the granular bed and the incipient failure point. In general, the shear stress increases with the adhesive energy. The sliding friction coefficient and the adhesive energy affect the Yield locus and therefore the angle of internal friction and the apparent cohesion. Two correlations were established between the angle of internal friction and sliding friction coefficient and between cohesion and adhesive energy. The effect of the initial consolidation on the shear test results is also discussed.

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“…At the other extreme, excessively free flow, aeratable pharmaceutical powders could cause flooding during the filling operation, thus again compromising the process and product quality. Therefore, it is necessary to monitor the flowability variation at each processing step with close precision [3] and take appropriate measures to ensure that a desirable powder flow condition is maintained. To investigate the flowability of different powders, the classical procedure is to perform laboratory scale tests based on Jenike's principle.…”

Section: Introductionmentioning

confidence: 99%