3948 XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3
feed, middle, and discharge positions. This information,
when processed with advanced analytics, allows one to esti-
mate more accurately several internal mill variables such as
Fill Level, Liner Damage, Impact Angle, Toe Angle, Impact
on Toe, and the relationship between the ball charge and
the ore charge within the mill. Note: These measurements
and correlations with traditional process variable signals are
discussed further in several dedicated sections of this paper.
In addition to the shell-based sensors, two fixed non-
moving sensors are positioned at the mill’s trunnion feed
and discharge points. These sensors provide information on
processing issues such as ore blocking, pooling, and peg-
ging. All five sensors enable real-time monitoring of the
slurry flow through the mill and current grinding efficiency
in the chamber.
ADVANCED ANALYTICS MEASUREMENTS
(AAM)
When combined with standard process measurements
(throughput, power, bearing pressure, solids, feed size, etc.),
the vibration profiles provided by the three shell sensors
provide new insights into mill operation via the Advanced
Analytics Measurements (AAM). These are multi-variable
models based on both vibration and typical process data
and, when combined with power curves (Powell, 2006),
result in three different operating modes, as shown in
Figure 3. For grinding optimization, the relevant AAM sig-
nals are shown below:
Liner Damage Level (LDL): A measurement that
indicates the extent of damage (wear) occurring in real-
time on the liners. A high LDL (70) value indicates a
higher probability of fracture in both the liners and grind-
ing media (balls) due to ‘steel-on-steel’ impacts and empty
mil condition. Conversely, a low LDL (30) indicates very
low ‘steel-on-steel’ impacts, resulting in over-protection of
the liners/media. By operating the mill in this manner, the
mill can be overfilled and potentially overloaded quickly.
Therefore, The optimal point is somewhere between these
limits (LDL ≈ 50), operating what the Beach Boys would
call ‘good vibrations’.
Impact Angle (IA): This measurement indicates the
angle at which the grinding media impacts inside the mill.
The Impact Angle (IA) helps identify the optimal point
of impact for maximum grinding efficiency, whether for
Impact Grinding or Attrition Grinding.
The optimal IA for Impact Grinding is generally
between 130 and 140 degrees. This condition leads to max-
imum throughput while providing the best possible trans-
fer size, optimum energy consumption, protection of liners
and grinding media, and safer operation for both people
and equipment. When Attrition Grinding is required (e.g.,
limited plant capacity), throughput will be limited, but
improved transfer size will be produced. The optimal angle
Figure 2. MillSlicerVIP Field Installation Components &Photos
feed, middle, and discharge positions. This information,
when processed with advanced analytics, allows one to esti-
mate more accurately several internal mill variables such as
Fill Level, Liner Damage, Impact Angle, Toe Angle, Impact
on Toe, and the relationship between the ball charge and
the ore charge within the mill. Note: These measurements
and correlations with traditional process variable signals are
discussed further in several dedicated sections of this paper.
In addition to the shell-based sensors, two fixed non-
moving sensors are positioned at the mill’s trunnion feed
and discharge points. These sensors provide information on
processing issues such as ore blocking, pooling, and peg-
ging. All five sensors enable real-time monitoring of the
slurry flow through the mill and current grinding efficiency
in the chamber.
ADVANCED ANALYTICS MEASUREMENTS
(AAM)
When combined with standard process measurements
(throughput, power, bearing pressure, solids, feed size, etc.),
the vibration profiles provided by the three shell sensors
provide new insights into mill operation via the Advanced
Analytics Measurements (AAM). These are multi-variable
models based on both vibration and typical process data
and, when combined with power curves (Powell, 2006),
result in three different operating modes, as shown in
Figure 3. For grinding optimization, the relevant AAM sig-
nals are shown below:
Liner Damage Level (LDL): A measurement that
indicates the extent of damage (wear) occurring in real-
time on the liners. A high LDL (70) value indicates a
higher probability of fracture in both the liners and grind-
ing media (balls) due to ‘steel-on-steel’ impacts and empty
mil condition. Conversely, a low LDL (30) indicates very
low ‘steel-on-steel’ impacts, resulting in over-protection of
the liners/media. By operating the mill in this manner, the
mill can be overfilled and potentially overloaded quickly.
Therefore, The optimal point is somewhere between these
limits (LDL ≈ 50), operating what the Beach Boys would
call ‘good vibrations’.
Impact Angle (IA): This measurement indicates the
angle at which the grinding media impacts inside the mill.
The Impact Angle (IA) helps identify the optimal point
of impact for maximum grinding efficiency, whether for
Impact Grinding or Attrition Grinding.
The optimal IA for Impact Grinding is generally
between 130 and 140 degrees. This condition leads to max-
imum throughput while providing the best possible trans-
fer size, optimum energy consumption, protection of liners
and grinding media, and safer operation for both people
and equipment. When Attrition Grinding is required (e.g.,
limited plant capacity), throughput will be limited, but
improved transfer size will be produced. The optimal angle
Figure 2. MillSlicerVIP Field Installation Components &Photos