Numerical and experimental analysis of influence of granule microstructure on its compression breakage

C. Wassgren, J. D. Litster, M. Dosta, S. Dale, S.Antonyuk, S.Heinrich
Powder Technology
breakage, Compression, Granules, microtomography

This contribution analyses how the distribution of components within granules, i.e., the granule microstructure, relates to the breakage characteristics of the final product. Granules produced from glass ballotini with a PVP binder by different formation techniques were characterized using X-ray computer microtomography (XRμT) to obtain the particle, binder, and pore distributions within the granules. The deformation and breakage behavior of granules were then obtained using single granule uniaxial compression tests.

To better understand the influence of the particle level interactions and granule microstructure influence on their deformation and breakage, discrete element method (DEM) simulations have been performed using the in-house-developed simulation framework MUSEN Dosta et al. (2013) . The granules were generated in a DEM model as a set of primary particles connected with solid bridge bonds. The XRμT measurements were used to reproduce the granule size, shape, and internal microstructure of experimental produced granules. In this way, the force-displacement curves were obtained with DEM using realistic granule microstructures.

The range of predicted granule strengths overlapped with the range of experimental measurements in most instances. The simulations were also used to demonstrate that granules with increase binder concentration toward the perimeter of the granule tend to have greater attrition resistance while increasing binder concentration at the core are more resistant to fragmentation. Development of this simulation tool will allow investigators to estimate the stability and predict optimal granule structure.

Keywords: granules, breakage, compression, microtomography.

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