Optimising the live capacity of gravity reclaim stockpiles
A new theory for funnel-flow with particular reference to gravity reclaim stockpiles is presented.
By Alan W Roberts, Stephen J Wiche and Tobias Krull
TUNRA Bulk Solids Handling Research Associates, The University of Newcastle, Australia.
The theory is based on hoop stress analysis in which the unconfined yield strength in the circumferential direction governs the diameter of the rathole that forms above the reclaim hopper and feeder. It is shown that the circumferential unconfined yield strength corresponds to the average of the major and minor consolidation stresses from the 2-dimensional axi-symmetric analysis. Confirmation of this approach is obtained from flow property tests in which the Flow Functions for the 2-dimensional and 3-dimensional cases are determined using the Jenike direct shear tester. The new procedures for funnel-flow analysis are described and the application to the prediction of stockpile draw-down and live capacity is illustrated by reference to a case study example.
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