XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3 3857
capacity of the drives will also be used to maintain voltage
stability on site.
Detection of Torsional Vibration signatures
The drive can be used as a sensor for torsional vibration
signatures. Torsional vibrations can have different potential
sources such as motor misalignment, bearings, mechanical
imbalances, process parameters etc. Electrical sources such
as variable speed drive control can also be a factor.
Speed and torque measurements from the drive can be
used to generate a spectrum which can be used to detect
anomalies such as gear tooth failure, imbalance in the mill,
rotor eccentricity, or shaft misalignment. Depending on the
nature of the anomalies, either active or passive damping
strategies can be implemented to counteract the oscillations
(Dr. Leitz, D. 2022). This along with the active load share
controller inherent in this system can reduce the amplitude
of certain oscillations. Special care must be taken while
applying damping strategies since simply damping them in
the control might shift them within the system. An addi-
tional benefit is that this approach of tracking and mea-
suring torsional vibration frequencies does not require the
addition of any extra equipment and is non-invasive.
Figure 12. (c) Speed profile of SAG Mill 1 for an 8-month period. The green line indicates the designed Mill Speed, and
the Red line indicated the maximum operating speed that can be achieved by the motors (not the critical speed) (d) Speed
profile of SAG Mill 2 for an 8-month period. The green line indicates the designed Mill Speed, and the Red line indicated the
maximum operating speed that can be achieved by the motors (not the critical speed).
(c)
(d)
capacity of the drives will also be used to maintain voltage
stability on site.
Detection of Torsional Vibration signatures
The drive can be used as a sensor for torsional vibration
signatures. Torsional vibrations can have different potential
sources such as motor misalignment, bearings, mechanical
imbalances, process parameters etc. Electrical sources such
as variable speed drive control can also be a factor.
Speed and torque measurements from the drive can be
used to generate a spectrum which can be used to detect
anomalies such as gear tooth failure, imbalance in the mill,
rotor eccentricity, or shaft misalignment. Depending on the
nature of the anomalies, either active or passive damping
strategies can be implemented to counteract the oscillations
(Dr. Leitz, D. 2022). This along with the active load share
controller inherent in this system can reduce the amplitude
of certain oscillations. Special care must be taken while
applying damping strategies since simply damping them in
the control might shift them within the system. An addi-
tional benefit is that this approach of tracking and mea-
suring torsional vibration frequencies does not require the
addition of any extra equipment and is non-invasive.
Figure 12. (c) Speed profile of SAG Mill 1 for an 8-month period. The green line indicates the designed Mill Speed, and
the Red line indicated the maximum operating speed that can be achieved by the motors (not the critical speed) (d) Speed
profile of SAG Mill 2 for an 8-month period. The green line indicates the designed Mill Speed, and the Red line indicated the
maximum operating speed that can be achieved by the motors (not the critical speed).
(c)
(d)