Investigation of Flow Channel Geometry and Draw-Down in Funnel-Flow Bins and Stockpiles

Abstract:

Over the past 50 years, a strong foundation for the professional discipline of bulk solids handling has been provided, but so far, the theories for predicting funnel-flow are still quite empirical. In most cases, only two-dimensional stress field models are applied, which overestimate the stable pipe or rathole dimensions defining the core of the funnel and lead to draw-down and live capacity determinations, which are too conservative. More recently, Roberts [ introduced a new, more realistic, hoop stress theory based on the three-dimensional stress state occurring in a rathole. To verify the validity of the new theory, the current research upon which this paper is based, involves an experimental study of rathole formation in laboratory scale model funnel-flow bins and gravity reclaim stockpiles. A two-dimensional laser line scanner is used to depict rathole profiles, while load cells and pressure sensors are applied to determine instantaneous loads and pressure conditions during filling, storage and discharge. Iron ore fines are used as the test material, with the test program including flat-bottom bins with different diameters as well as varying filling levels and outlet diameters and stockpiles with variable heights and outlet diameters. The tests demonstrate the capability of laser scanning to describe rathole profiles. In addition, the suitability of the load cells and pressure sensors to describe the relevant funnel-flow parameters is shown.

• Periodical: Advanced Materials Research (Volume 508)
• Pages: 16-20
• DOI: https://doi.org/10.4028/www.scientific.net/AMR.508.16
• Online since: April 2012
• Authors: Yan Yan He, Alan W. Roberts, Jan Dirk Prigge
• Keywords: Funnel-Flow, Hoop Strength, Laser, Rathole, Stockpile

References

[1] A. W. Roberts, T. Krull, S. J. Wiche, Optimising the live capacity of gravity reclaim stockpiles, Australia Bulk Handling Review, February 2009, pp.72-76.

[2] A. W. Jenike, Bulletin 123: Storage and flow of solids, University of Utah, Salt Lake City, UT, November 1964, pp.57-68, pp.188-193.

[3] A. W. Jenike, J.R. Johanson, J.W. Carson, Bin loads- Part 4: Funnel-Flow Bins, ASME, Journal of Engineering for Industry, Series B 95 (1), (1973) 13-16.

DOI: 10.1115/1.3438089

[4] J. R. Johanson, Effect of initial pressures on flowability of bins, ASME Journal of Engineering for Industry, Series B 91 (2) (1969) 395–399.

DOI: 10.1115/1.3591579

[5] J. W. Carson, R.T. Jenkyn, Load development and structural considerations in silo design, Reliable Flow of Particulate Solids II, Oslo, Norway, August (1993).

[6] W. McBride, Mechanics of Bulk Solids Stockpiles, PhD Thesis, The University of Newcastle, Australia, 2001, pp.69-88, pp.140-143.

[7] H. Y. Jeong, Numerical Simulations of Stresses Under Stockpiled Mass Over Ground With or Without Loadout Tunnel, PhD Thesis, The University of Western Ontario, Canada, 2005, pp.223-248.

[8] A. W. Roberts, Characterisation for Hopper and Stockpile Design, Chapter 3, Characterization of Bulk Solids, Ed D, McGlinchey, Blackwell Publishing, 2005, pp.85-131.

DOI: 10.1002/9781444305456.ch3