Please cite this article in press as: Salehi, H., et al. A comparison between powder flow property testers. Particuology (2016), http://dx.doi.org/10.1016/j.partic.2016.08.003 ARTICLE IN PRESS G Model PARTIC-951; No. of Pages 11 Particuology xxx (2016) xxx–xxx Contents lists available at ScienceDirect Particuology journal homepage: www.elsevier.com/locate/partic A comparison between powder flow property testers Hamid Salehi, Diego Barletta, Massimo Poletto ∗ Dipartimento di Ingegneria Industriale, Università degli Studi di Salerno, Via Giovanni Paolo II, 132, 84084 Fisciano, SA, Italy a r t i c l e i n f o Article history: Received 9 May 2016 Received in revised form 28 July 2016 Accepted 30 August 2016 Available online xxx Keywords: Powder flow property Shear tester Flowability Jenike tester Schulze tester Brookfield powder flow tester a b s t r a c t In this work, three different shear testers—the Jenike shear cell tester, the Schulze ring shear tester, and the Brookfield powder flow tester—were compared in terms of the raw shear stress time series, yield loci points, angle of internal friction, cohesion, and unconfined yield strength. The three different powders of dolomitic lime, calcium lactate, and calcium carbonate were used for these comparisons. These three powders were characterized into different flowability classes using the Jenike classification, wherein dolomitic lime falls into the cohesive range, calcium lactate falls into the free-flowing range, and calcium carbonate falls into the very cohesive range. Results showed that the best agreement between the testers was found with moderately cohesive powders such as dolomitic lime. Furthermore, the free-flowing material tends to produce more consistent data between the three testers in terms of shear stresses and yield loci. It should be noted that the pre-shear data of free-flowing powder obtained by the Jenike shear cell must be appropriately interpreted. The largest differences between the testers are found with calcium carbonate, which is a highly compressible powder. The ways in which a high powder compressibility can differently affect the results obtained with the different testers were discussed. © 2016 Chinese Society of Particuology and Institute of Process Engineering, Chinese Academy of Sciences. Published by Elsevier B.V. All rights reserved. Introduction Shear testers are important instruments for the design of reli- able solids handling equipment such as hoppers, silos, and storage bins. The design procedure for this type of equipment requires knowledge of powder flowability and other flow property data that can be obtained using shear testers. Powder flowability test meth- ods have been divided (Schwedes, 2003) into three main categories: (a) tests for non-compacted powders, such as measuring the angle of repose; (b) tests for tapped powder, such as measuring the Haus- ner ratio or the Carr index; and (c) tests for consolidated powders, such as shear testers (Jenike and Schulze shear testers). The first two methods are generally considered insufficiently accurate and reliable to characterize powders, and standardized procedures therefore must be used to obtain more repeatable data (Santomaso, Lazzaro, & Canu, 2003). Quantitative results from the methods classified as (a) and (b) above can scarcely be used in design procedures but are suited for a general classification of particulate materials. Meanwhile, shear testers include standard- ized procedures, and therefore provide more precise and physically meaningful results to be used for design purposes in industrial ∗ Corresponding author. Fax: +39 089 96 8781. E-mail address: mpoletto@unisa.it (M. Poletto). applications. These systems can be used also for the classification of powders (Schulze, 1996a,b). Krantz, Zhang, and Zhu (2009) have compared different static and dynamic techniques for characteriz- ing powders, and have concluded that the proper characterization technique should be selected on the basis of its ability to properly reproduce the state of stress and powder compaction close to the powder process condition. Furthermore, for certain testers the spe- cific measurement procedure can affect the results. For example, Han, Dhodapkar, and Gong (2014) assessed the time consolidation effect on the flow function of different solids at different shear rates and reported that varying the shear rates will affect the time consol- idation flow function values of sticky pellets. However, they found that varying the shear rate did not affect the flowability of non- sticky and soft-and-non-sticky powders. Similar conclusions were drawn by Vasilenko, Koynov, Glasser, and Muzzio (2013). Other process parameters have been verified to be important, such as the particle size distribution (Lu et al., 2009; Lu, Guo, Liu, & Gong, 2015), the consolidation level (Saw, Davies, Jones, & Paterson, 2014), the moisture content (Landi, Barletta, & Poletto, 2011), and the sys- tem temperature (Faqih, Mehrotra, Hammond, & Muzzio, 2007; Tomasetta, Barletta, & Poletto, 2014). Non-standardized tester pro- cedures have been proposed for low-consolidation (Freeman, 2007; Tomasetta, Barletta, Lettieri, & Poletto, 2012) and for biomass par- ticulate solids (Miccio, Barletta, & Poletto, 2013). http://dx.doi.org/10.1016/j.partic.2016.08.003 1674-2001/© 2016 Chinese Society of Particuology and Institute of Process Engineering, Chinese Academy of Sciences. Published by Elsevier B.V. All rights reserved.