Correlation between Powder Flow Properties Measured by Shear Testing and Hausner Ratio. (2015)

• Record Type: Journal Article
• Authors: Saw, Horng Yuan; Davies, Clive E.; Paterson, Anthony H.J.; Jones, Jim R.
• Is Part Of: Procedia engineering. Volume 102(2015)
• Page Start: 218
• Page End: 225
• Publication Date: 2015
• Subjects: Bulk density -- cohesion -- Hausner ratio -- powder flow function -- tapped density; Engineering -- Congresses; Engineering -- Periodicals; Engineering; Conference proceedings; Periodicals; 620.005
• DOI: 10.1016/j.proeng.2015.01.132
• Languages: English
• ISSNs: 1877-7058

Abstract

Abstract: Shear testing provides rigorous estimates of flow properties relevant to the characterization, handling, and processing of powders, and is a necessary test procedure in the formal design of powder storage facilities. However, despite the automation of modern test equipment, it can be time consuming and expensive. In contrast, measurement of bulk density is straightforward and less laborious, and tapping devices are cheaper. Here we explore the relationship between Hausner ratio and cohesion and also examine correlation between Hausner ratio, σ c / σ y, and σ pre for a suite of 13 milled and 2 spray-dried lactose powders, 3 sand samples and 3 samples of refractory dust; Hausner ratio is the ratio of tapped bulk density to loose bulk density, σ c is major consolidation stress, σ y is unconfined yield stress and σ pre is preconsolidation stress. Cohesion and flow function were measured with an annular shear cell at values of σ pre up to 5 kPa. Loose poured bulk density was measured following a modified New Zealand standard and tapped density measurement was based on a method for dry dairy products and the European Pharmacopoeia; Hausner ratio at 1250 taps was used. Our results show that cohesion at σ pre of 0.31 kPa, 0.61 kPa, 1.20 kPa, 2.41 kPa, and 4.85 kPa correlates linearly with Hausner ratio; the slope and intercept of the correlation are functions of σ pre . A plot of σ c / σ y against Hausner ratio shows an exponential decay trend and regression yields two fitting parameters that correlate well with σ pre . These correlations are potentially useful for assessing flow characteristics when shear testing cannot be performed.