6
In the yellow zone, vibration is low as the Impact Angle
drops below the Toe Angle, typically when the mill overfills.
In the white zone, the mill operates optimally, with
impacts occurring on the Toe of the load.
The vibration trends (right-hand side) show 24-hour
operation periods for each zone. This trend illustrates that
such events can last several hours, causing continued liner
and grinding media damage, as shown in the top trend.
Adjusting variables such as mill speed, water addition, or
throughput in real time helps avoid the red and yellow
zones, as demonstrated in Figure 6.
In Figure 6, the left-hand side shows the reference
period before implementing a controller to regulate LDL.
The blue trend represents manual control, where high-
vibration events are more frequent. Once the controller is
activated (green trend), it dynamically adjusts mill speed,
water ratio, and throughput in real time, significantly
reducing high LDL events. The most recent data shows
further improvement in minimizing low LDL events after
increasing the maximum RPM limit based on previous
LDL values.
A detailed analysis reveals that high-vibration events
often occur during periods of low RPM (major opportu-
nity), where throughput is limited, as illustrated in Figure 7.
Proper adjustments to RPM, mill solids, and throughput
ensure consistent operation within acceptable LDL ranges,
reducing long-term damage to liners and grinding media.
Liner Wear
Liner wear is an inevitable consequence of grinding that
affects the overall performance of the process. In the late
20th century, variable speed mills were introduced to com-
pensate for liner wear, minimize impact and extend liner
life. This is achieved by initially starting the liner campaign
at a lower speed and gradually increasing the speed as the
liner wears to inject more grinding energy for reduced liner
ball throw (trajectory).
Impact Angle Increase Due to Liner Wear
As previously mentioned, the Impact Angle (IA) is cal-
culated using AAM and indicates the angle at which the
media and slurry land inside the mill. Figure 8 corresponds
Figure 6. LDL conditions
Figure 7. LDL opportunities
In the yellow zone, vibration is low as the Impact Angle
drops below the Toe Angle, typically when the mill overfills.
In the white zone, the mill operates optimally, with
impacts occurring on the Toe of the load.
The vibration trends (right-hand side) show 24-hour
operation periods for each zone. This trend illustrates that
such events can last several hours, causing continued liner
and grinding media damage, as shown in the top trend.
Adjusting variables such as mill speed, water addition, or
throughput in real time helps avoid the red and yellow
zones, as demonstrated in Figure 6.
In Figure 6, the left-hand side shows the reference
period before implementing a controller to regulate LDL.
The blue trend represents manual control, where high-
vibration events are more frequent. Once the controller is
activated (green trend), it dynamically adjusts mill speed,
water ratio, and throughput in real time, significantly
reducing high LDL events. The most recent data shows
further improvement in minimizing low LDL events after
increasing the maximum RPM limit based on previous
LDL values.
A detailed analysis reveals that high-vibration events
often occur during periods of low RPM (major opportu-
nity), where throughput is limited, as illustrated in Figure 7.
Proper adjustments to RPM, mill solids, and throughput
ensure consistent operation within acceptable LDL ranges,
reducing long-term damage to liners and grinding media.
Liner Wear
Liner wear is an inevitable consequence of grinding that
affects the overall performance of the process. In the late
20th century, variable speed mills were introduced to com-
pensate for liner wear, minimize impact and extend liner
life. This is achieved by initially starting the liner campaign
at a lower speed and gradually increasing the speed as the
liner wears to inject more grinding energy for reduced liner
ball throw (trajectory).
Impact Angle Increase Due to Liner Wear
As previously mentioned, the Impact Angle (IA) is cal-
culated using AAM and indicates the angle at which the
media and slurry land inside the mill. Figure 8 corresponds
Figure 6. LDL conditions
Figure 7. LDL opportunities