Comparison of Methods for Evaluation of Flow Properties of Powders and Granulates

Abstract

Powder mixtures and granulates with bulk densities ranging from 0.35-0.89 g.ml⁻¹ were tested regarding flow properties using the following methods: the Hausner ratio (packed bulk density/loose bulk density), rate of packing on tamping, flow rate through a 30 mm orifice, orifice diameter allowing free flow, and “drained” angle of repose.

The Hausner ratio and the angle of repose could be measured with a relative standard deviation of about 2 %. The orifice diameter could also be determined accurately and these three methods correlated well with each other.

The flow rate could only be measured on free flowing materials and the packing rate correlated poorly with the other methods.