Granular Flow - Application
3D SAG mill
DEM simulation results have been undertaken of a full-scale 3D SAG
(Semi-Autogenous) mill. The operating parameters of the mill have been
varied to analyse their influence on mill operation.
The figure/animation below illustrates the results on a 3D DEM
simulation of 281,000 spherical particles (rocks and balls).
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mill diameter :
mill length :
lifters - number :
profile :
fill level :
mill speed :
charge :
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10 m
4 m
72
85 degrees
30%
75% critical
rocks (s.g. = 4.0; 20 to 250 mm)
balls (s.g. = 7.8; 50 to 200 mm)
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3D DEM simulation of the SAG
mill
(particles coloured by velocity) |
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QuickTime animation
(268x276 pixels; 2.0 MB) |
The shape of the cascading free surface of the charge is clearly visible.
The rocks and ball avalanche down the steep slope on the left side of the
mill and then flow more slowly across the gently angled down slope to the
toe region. A significant amount of the charge is cataracting even at this
modest speed of 75% critical because of the use of 72 rows of large blocky
lifters. The high shear experienced by much of the charge is demonstrated
by presence of the long blue layer of slow moving or stationary material
in the middle of the charge which is bounded by rapidly moving (coloured
green) material above and below.
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