Physical characteristics of ground switchgrass related to bulk solids flow.

Switchgrass has potential as an energy crop, but problems with handling and flowability hinders its utilization. The primary objective of this study was to investigate the fundamental flow-related physical characteristics of switchgrass particles ground through three hammermill screen sizes of 6.4, 3.2 and 1.6 mm. Physical properties were determined through sieve analysis, density testing, image analysis, angle of repose and fractal analysis. The geometric mean diameter and geometric standard deviation of the ground material decreased with size reduction. Particle size significantly influenced particle and bulk density. Similar conclusions were made for angle of repose; values decreased with size reduction. Shape and surface parameters from image and fractal analyses were not significantly different among particle sizes. Non-spherical, needle-shaped particles were maintained through size reduction. Particle size reduction may slightly improve the flow of ground switchgrass bulk, but will always experience some degree of flow problems in regular storage silos and hoppers. [Display omitted] • The geometric mean diameter and geometric standard deviation of the ground material decreased with size reduction. • Particle size significantly influenced particle and bulk density. • The angle of repose decreased with size reduction. • Shape and surface parameters were not significantly different among particle sizes. • Grinding does not improve the aspect ratio of ground switchgrass, making it inherently cohesive. [ABSTRACT FROM AUTHOR]