3760 XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3
differ from the radial design in terms of grates’ positions.
The seven designs for the curved lifter bars are shown in
Figure 4.
A parameter called mean relative radial position of the
grates’ openings is often used to characterize the grates posi-
tion relative to the radial distance from the mill’s center.
The value of this parameter is a weighted radial position
and is calculated using following formula:
R
m i /r
/riai
c =(1)
where ai is the open area of all holes at the radial posi-
tion ri and Rm is the radius of the mill inside the liners.
Using Eq.(1) the mean relative radial position of the grates
for the seven cases could be easily calculated and the values
are shown in the Table 3. It must be mentioned here that
the calculated mean relative radial position of the grates are
the same for both radial and curved lifter bars.
Results for the Radial Discharge System
Results similar to those shown in Figure 2 were gener-
ated after the simulation for the seven designs were com-
pleted. In Figure 5 three snapshots from the simulations
for Radial1, Radial4 and Radial7 are presented in order to
visually compare the discharge rates and the amounts of
solids and slurry present in the pans.
The images show that the amounts of slurry and solids
discharged are decreasing as the holes are moved towards
the center of the mill. There is no slurry discharged for the
Radial7 case, which shows that under the current operating
conditions for the mill the grates are too high for the slurry
to reach them. There is also a small amount of solids dis-
charged for Radial7 case.
Figure 5 also shows the slurry flowing out of the mill
mainly through the grates positioned in the range 8 o’clock
to 10 o’clock, while the solids are flowing out of the mill
over a larger range between 6 o’clock and 10 o’clock. These
observations from the simulations are similar to those
observed by Latchireddi and Morrell (2003) in their experi-
mental work with open grates mill at medium flow rates.
Under these conditions (medium flow rates) the slurry is
swept up the charge, and there is not much slurry at the toe
of the charge.
The next set of graphs in Figure 6 show the mill dis-
charge rates, inwards and outwards rates through the grates’
openings and the amount of solids and slurry recirculated
in the pans as a function of the mean relative radial position
of the grates.
Figure 4. Radial position of the grates for the curved discharge design
Table 3. Mean relative radial position of the grates for the
seven simulated designs
Design Mean Relative Radial Position
Radial1(Curved1) 0.918
Radial2(Curved2) 0.876
Radial3(Curved3) 0.835
Radial4(Curved4) 0.794
Radial5(Curved5) 0.753
Radial6(Curved6) 0.711
Radial7(Curved7) 0.670
differ from the radial design in terms of grates’ positions.
The seven designs for the curved lifter bars are shown in
Figure 4.
A parameter called mean relative radial position of the
grates’ openings is often used to characterize the grates posi-
tion relative to the radial distance from the mill’s center.
The value of this parameter is a weighted radial position
and is calculated using following formula:
R
m i /r
/riai
c =(1)
where ai is the open area of all holes at the radial posi-
tion ri and Rm is the radius of the mill inside the liners.
Using Eq.(1) the mean relative radial position of the grates
for the seven cases could be easily calculated and the values
are shown in the Table 3. It must be mentioned here that
the calculated mean relative radial position of the grates are
the same for both radial and curved lifter bars.
Results for the Radial Discharge System
Results similar to those shown in Figure 2 were gener-
ated after the simulation for the seven designs were com-
pleted. In Figure 5 three snapshots from the simulations
for Radial1, Radial4 and Radial7 are presented in order to
visually compare the discharge rates and the amounts of
solids and slurry present in the pans.
The images show that the amounts of slurry and solids
discharged are decreasing as the holes are moved towards
the center of the mill. There is no slurry discharged for the
Radial7 case, which shows that under the current operating
conditions for the mill the grates are too high for the slurry
to reach them. There is also a small amount of solids dis-
charged for Radial7 case.
Figure 5 also shows the slurry flowing out of the mill
mainly through the grates positioned in the range 8 o’clock
to 10 o’clock, while the solids are flowing out of the mill
over a larger range between 6 o’clock and 10 o’clock. These
observations from the simulations are similar to those
observed by Latchireddi and Morrell (2003) in their experi-
mental work with open grates mill at medium flow rates.
Under these conditions (medium flow rates) the slurry is
swept up the charge, and there is not much slurry at the toe
of the charge.
The next set of graphs in Figure 6 show the mill dis-
charge rates, inwards and outwards rates through the grates’
openings and the amount of solids and slurry recirculated
in the pans as a function of the mean relative radial position
of the grates.
Figure 4. Radial position of the grates for the curved discharge design
Table 3. Mean relative radial position of the grates for the
seven simulated designs
Design Mean Relative Radial Position
Radial1(Curved1) 0.918
Radial2(Curved2) 0.876
Radial3(Curved3) 0.835
Radial4(Curved4) 0.794
Radial5(Curved5) 0.753
Radial6(Curved6) 0.711
Radial7(Curved7) 0.670