A Fundamental Approach to Belt Feeder Loads

Belt Feeder Design

A Fundamental Approach to Belt Feeder Loads

How to assess loads on Feeders, (practically)
Feeders are widely used for metering bulk solids and discharging the contents of hoppers and silos. Numerous attempts have been made to describe the process of feeding but quite often they only cover certain products and hopper construction. In this article the reader will find a more general approach to this field of problems.
(ed. WoMaMarcel - 01/9/2015)
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Recommended features to minimise belt feeder loads:

  • Ensure that the minimum width of the hopper outlet exceeds the critical arching dimension for the ‘worst’ conditions that must be accommodated, but not by a wide margin. (A vibrator may overcome “Worst’ flow conditions).
  • Ensure the hopper outlet length is at least three times its width, to secure the full flow benefits of a slot outlet, but not much longer, to maximise the inclination of the shear plane.
  • End the inclined hopper walls with an increasing clearance to the belt along the line of travel to create a stressed arch that can diverge in failure as material moves along the belt.
  • Make the exit opening match the stressed arch (in the shape of a parabola, with the ends at the bottom of the hopper ‘V’ walls inclined at (α + φ) to the vertical).
  • Allow material to discharge by repose flow from the inclined side clearance to encourage slip on the hopper walls.
  • Base the overpressure on the ‘easiest’ flow material and stresses acting on the  widest part of the hopper outlet.
  • On initial fill, run the feeder for about half the length of the outlet when the level of material covers the outlet to a depth of about three times its width, to develop a shear plane in lightly stressed conditions.
  • Leave a ‘heel’ of material in the hopper, to allow re-start under developed stress conditions. (If not practical, consider retractable rods that are inserted in empty conditions and retracted for restart with belt running).

This review highlights the great benefits of generating ‘live flow’ over the total hopper outlet area, paying attention to design detail for the feeder interface, making special design arrangements for initiating the discharge of either hard, granular bulk materials to avoid unacceptable load conditions or cohesive material that would otherwise demand an unacceptably wide span when handling such products. Brute force is a very poor solution. Project engineers tend to consider detail equipment design to be the responsibility of the draughtsman, who pays attention to engineering aspects, but is not a specialist in powder technology. The interface between hoppers and feeders merits close attention as it is a major factor in capital and running costs.


[1] Roberts, Alan: Design and application of feeders for the controlled loading of bulk solids onto conveyor belts; University of Newcastle.
[2] Moore, Brian: Flow properties and design procedures for coal storage bins; Thesis, University of Wollongong 1998.
[3] Ooi.J.Y., J.M. Rotter: Arching propensity in coal bunkers with non-symmetric geometries; BCURA Project B54. 2005.
[4] Holmes, Corin, et al.: Start-up and Running Loads Exerted by Bulk Solid Materials on Extractive Belt Feeders: Experimental findings compared with available models; 10th ICBMH. Brisbane. 2009
[5] Allen, Leo: Belt feeder head load investigation; CEEP Seminar, 2013
[6] Jie, Guo: Investigation of arching behaviour under surcharge pressure in mass flow bins and stress states at hopper/feeder interface; Thesis, University of Wollongong 2014.
[7] Ariza-Zafra, Karol: Improving  performance of discharge equipment for coals with poor handling characteristics; Thesis, The Wolfson Centre 2015.
[8] Bates, Lyn: The blockage of a hopper outlet or other flow channel by lumps; Ajax publication.
[9] McGee, Eddie and Lyn Bates: Design Considerations for Loads on Feeders; Bulk Solids Europe 2012 Berlin, Germany, October 11-12, 2012

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