XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3 3775
Figure 8 shows the spatial distribution of power
between shear and impact components of collisions in
the 1.8 m Ø mill and 0.3 m Ø mill. Figure 8 shows that
the regions of high dissipation (shear and impact) become
more well defined as the mill diameter is increased, which is
likely to yield consistent grinding performance. The regions
of high dissipation are narrow in the small mill, especially
for impact component of collisions.
The results from the DEM simulations presented here
show that the mill collision environment is different for
mills of different sizes, partly owing to the different lifter
configuration, for which there is little (or no) room to
change in lab and pilot scale mills. Carvalho (2013) showed
that for same ball size, mill filling level and speed, the spe-
cific breakage rate function is distinctly different in mills of
different sizes (lab scale and pilot scale). The observations
suggests that scale up models should consider the changes
in collision environment when scaling up grinding per-
formance data from lab/pilot scale mills to industrial scale
mills.
CONCLUSIONS
• The results from DEM simulations performed show
that for the four mills simulated, the ball top-up size
changes the mill collision environment. Changing
from large ball top-up size to smaller ball top-up sizes
increases the proportion of power that is taken by the
shear component of collisions. The change also shifts
collision environment (described by shear) from
being dominated by high-energy collisions to being
dominated by low-energy collisions.
• The results from DEM simulations performed show
that mill diameter changes the collision environ-
ment. Moving from lab mills to pilot mills it was
observed that the proportion of power that is taken
by the shear component of collisions increases signif-
icantly. The spatial maps of collision power show that
the region of high power dissipation is well defined
in large mills.
• The changes in mill collision environment because of
ball size and mill size should be considered in mecha-
nistic/ scale up models for predicting grinding per-
formance, and in media wear models.
ACKNOWLEDGMENTS
The authors wish to thank and acknowledge Mintek for
financial support and permission to publish this paper.
REFERENCES
Aldrich, C. 2013. Consumption of steel grinding media in
mills–A review. Minerals Engineering 49: 77–91.
Austin, L., Klimpel, R., and Luckie, P. 1984. Process
Engineering of Size Reduction: Ball Milling, Society of
Mining Engineers. AIME, p. 112–113.
Figure 8. Spatial distribution maps of power dissipation, (top) 1.8 m Ø mill (bottom)
0.3 m Ø mill (left) shear power (right) impact power
Figure 8 shows the spatial distribution of power
between shear and impact components of collisions in
the 1.8 m Ø mill and 0.3 m Ø mill. Figure 8 shows that
the regions of high dissipation (shear and impact) become
more well defined as the mill diameter is increased, which is
likely to yield consistent grinding performance. The regions
of high dissipation are narrow in the small mill, especially
for impact component of collisions.
The results from the DEM simulations presented here
show that the mill collision environment is different for
mills of different sizes, partly owing to the different lifter
configuration, for which there is little (or no) room to
change in lab and pilot scale mills. Carvalho (2013) showed
that for same ball size, mill filling level and speed, the spe-
cific breakage rate function is distinctly different in mills of
different sizes (lab scale and pilot scale). The observations
suggests that scale up models should consider the changes
in collision environment when scaling up grinding per-
formance data from lab/pilot scale mills to industrial scale
mills.
CONCLUSIONS
• The results from DEM simulations performed show
that for the four mills simulated, the ball top-up size
changes the mill collision environment. Changing
from large ball top-up size to smaller ball top-up sizes
increases the proportion of power that is taken by the
shear component of collisions. The change also shifts
collision environment (described by shear) from
being dominated by high-energy collisions to being
dominated by low-energy collisions.
• The results from DEM simulations performed show
that mill diameter changes the collision environ-
ment. Moving from lab mills to pilot mills it was
observed that the proportion of power that is taken
by the shear component of collisions increases signif-
icantly. The spatial maps of collision power show that
the region of high power dissipation is well defined
in large mills.
• The changes in mill collision environment because of
ball size and mill size should be considered in mecha-
nistic/ scale up models for predicting grinding per-
formance, and in media wear models.
ACKNOWLEDGMENTS
The authors wish to thank and acknowledge Mintek for
financial support and permission to publish this paper.
REFERENCES
Aldrich, C. 2013. Consumption of steel grinding media in
mills–A review. Minerals Engineering 49: 77–91.
Austin, L., Klimpel, R., and Luckie, P. 1984. Process
Engineering of Size Reduction: Ball Milling, Society of
Mining Engineers. AIME, p. 112–113.
Figure 8. Spatial distribution maps of power dissipation, (top) 1.8 m Ø mill (bottom)
0.3 m Ø mill (left) shear power (right) impact power