Measuring permeability and flowability of powders at various packing fractions--颗粒学报PARTICUOLOGY

Lupo, M., Neveu, A., Gemine, T., Francqui, F., & Lumay, G. (2025). Measuring permeability and flowability of powders at various packing fractions. Particuology, 101, 107-116. https://doi.org/10.1016/j.partic.2024.03.008

Measuring permeability and flowability of powders at various packing fractions

Marco Lupo^a *, Aurélien Neveu^a, Thomas Gemine^{a b}, Filip Francqui^a, Geoffroy Lumay^b

a Granutools, Rue Jean-Lambert Defrêne, 107, 4340, Awans, Belgium
b GRASP Laboratory, CESAM Research Unit, University of Liège, Allée du 6 Août, 19 (B5a, Office 3/53) B-4000 Sart Tilman, Belgium

10.1016/j.partic.2024.03.008

Volume 101, June 2025, Pages 107-116

Received 1 December 2023, Revised 7 March 2024, Accepted 27 March 2024, Available online 4 April 2024, Version of Record 29 May 2025.

E-mail: marco.lupo@granutools.com

Highlights

• A method to measure permeability at various packing fractions and low consolidation is proposed.

• The larger the packing fraction the lower the permeability.

• The permeability classification changes with the densification conditions.

• The permeability can be used to predict the powder flowability.

Abstract

Permeability is a key powder property for many industrial applications as it affects the flowability during powder handling and the quality of the final product. Indeed, the ability of air to pass through a powder bed, quantified by permeability, is decisive for die or bag filling, dry powder inhalers, silo discharge, pneumatic transport, fluidized bed, etc. Usually, the permeability is measured on a powder bed subjected to high consolidation stresses and without the possibility to control the packing fraction of the powder. In the present study, we show how GranuPack measurement can be combined with a permeability measurement cell to measure the permeability at low consolidation and for various packing fractions, which correspond to many process conditions. A selection of usual powders (pharmaceutical excipients and abrasives) has been tested and the results highlight how the permeability can be used to obtain additional information about powder behavior. For that, a two levels analysis is proposed: an entry-level based on straightforward parameters like initial and final (after the tapping process) permeability and a more advanced level based on two new metrics. These metrics are the permeability ratio and the rate of variation of permeability. These parameters are directly related to the powder cohesiveness and hence can be used to complement the classical flowability indexes.

Graphical abstract

Keywords

Permeability; Packing fraction; Low consolidation; Flowability; Tapped density

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