3701 nw 40 th terrace, #1, gainesville, florida 32606 usa mineralscan millslicer general overview by...

3701 NW 40th Terrace, #1, Gainesville, Florida 32606 USA

MineralScan MillSlicer General Overviewby Dr. Karl Gugel

Director, Digital Control Lab & Lecturer/Researcher, ECE Dept. Univ. of Florida

Main

Unit

power 90 – 240 VAC 50/60 Hz

(4) 4-20 mA cables (1000m/3000ft max)

(1) ethernet cable (100m/300 ft max)

AG/SAG

wet or dry mill

RF link

(10 m)

(2) sensors to main unit cable (30m/90ft)

transmitter, sensor,

index and battery

inlet sensoroutlet sensor

magnetic

index boom


MineralScan MillSlicer - System Components

Fixed Position Vibration Sensor

Shell Mounted Transmitter & Battery Pack

Shell Mounted Battery Pack, Transmitter & T Sensor



Magnetic Boom & T Sensor w/Transmitter



Main PC Unit Mounted Near Mill

Main PC Unit (inside view)

Pole MountRF Antenna


MineralScan MillSlicer – Installation Steps1. Mill is cleaned for T Sensor, Transmitter and Battery Pack2. T Sensor, Transmitter and Battery Pack are placed on the mill3. Magnetic Index Boom Placement at a fixed position at the end of the mill

- Verify 4 cm or less clearance/alignment between boom & T Sensor4. Metal templates are placed around the T Sensor, Transmitter and Battery Pack

- high temperature epoxy is applied to fix the templates 5. Main Unit placement, such that it is within 30 meter from each end of the mill - fixed position sensor cable lengths are typically 30 meters6. Attach the receive antenna to the Main Unit

- verify transmitter/Main Unit communication (50 meters max, line of sight)

- relocation of the Main Unit may be required so it is important to verify communication before connecting the ethernet & 4-20mA signals

7. Fixed position vibration sensors placement (Inlet & Outlet)8. Attach (4) twisted pair 4-20mA cables from Main Unit to a PLC in MCC room - verify 24VDC is being supplied by the PLC via LEDs on 4-20mA boards 9. Attach standard Ethernet cable between Main Unit

- PC can be electrical or control room and should be tied to plant’s WLAN


MineralScan MillSlicer – Calibration & 4-20 mA Outputs

1. Quick Calibrations are made on all three vibration sensors- estimate current fill level and set the sensitivity (signal dynamic range)- this takes ~1 minute per sensor and is very easy to learn

2. Set ranges (sensitivity) for the Toe Entropy signal - ~1 minute to set and again is very easy to learn and adjust

3. Observe trends and adjust the sensitivity for 3 vibration inputs and Toe Entropy if needed. Note: It is important to run the mill between normal operation and 30% of normal operation (~30% full) to observe new signal trends.

(4) 4-20 mA Output Definitions:

i. Inlet fill level (0% => 4 mA, 100% full => 20 mA)ii. Outlet fill level (0% => 4 mA, 100% full => 20 mA)iii. Shell sensor fill level (0% => 4 mA, 100% full => 20 mA)

iv. Toe Entropy (4 mA => min. liner damage, 20 mA => major liner damage)


KGHM/RMNC MillSlicer – Polar Results - Ore Type Detection

Hard Ore (88% Full) Hard Ore (12% Full) Soft Slurry (Mud)

1. Hard/Normal Ore has a well defined toe area vs. none for the muddy type2. Toe Entropy is a measure of the sharpness of the polar plot in an predefined

arc in the toe region. 3. As the mill empties, the toe signal begins to sharpen and is a good indicator

of when balls are striking the mill shell. i.e. “Metal on Metal” condition.


Barrick Gold MillSlicer – Polar Results - Operators Guide

Case 1. Empty Mill w/Excessive RPMs Case 2. Empty Mill w/Good RPMs Case 3. Full Mill & Cascade Grinding

mill rotation

135O

mill rotation

135O

mill rotation

135O

Ball trajectory

Bad Better Best!

liner strike energy liner strike energy

• Mill is rotating in a clockwise direction

• Sensor on shell measures vibration energy in the full rotation and energy is plotted increasing toward the center of the plot

• RPMs are too high so balls strike high on the opposite side of the liner causing sharp energy peaks from 90 – 135 degrees.

• Extreme excessive wear/damage to the liners

• Snap shot taken on a mill being ground out at low speed (85% speed)

• No sharp peaks from 90 – 135 degrees which is good

• Liner strike energy from 135 – 270 degrees is high but there is nothing we can do about this, it is a result of the mill being empty

• Grind-outs should be always done at low speeds (80-85%) by cutting the feed

• When the mill begins to fill to levels above 50% on the shell sensor fill level trend, we see a focusing of the grinding energy in the region from 135 – 180 degrees

• Optimal cascade grinding is occurring and we are operating the SAG mill per it’s intended design

• Ball to liner strike energy significantly reduces to very low levels. i.e. compare the liner strike energy between Cases 2 and 3 from 180 – 270 degrees

• Optimal grinding & minimal liner damage!


Typical Expert System Control (RNMC) – Bearing Pressure

Signal Definitions:

Green - Inlet Sensor, Blue - Outlet Sensor, Yellow - Shell Sensor Light Purple - Toe Entropy, Red - Toe (unused), White - Shoulder (unused) Olive - Mill RPM, Purple - Mill Pressure, Teal Blue - Mill Feed

Note: Toe Entropy Signal 4-20mA signal was inverted during this test to visually correlate with the fill level signals.

Hard/Coarse Ore

Feed

Speed

Pressure

Toe Entr

In Vib

Out Vib

Shell Vib


MillSlicer RNMC Fill Level Control – Outlet & Shell Sensor

Signal Definitions:

Green - Inlet Sensor, Blue - Outlet Sensor, Yellow - Shell Sensor Light Purple - Toe Entropy, Red - Toe (unused), White - Shoulder (unused) Olive - Mill RPM, Purple - Mill Pressure, Teal Blue - Mill Feed

Note: Toe Entropy Signal 4-20mA signal was inverted during this test to visually correlate with the fill level signals.

Hard/Coarse Ore

Feed

Speed

Pressure

Toe Entr

In Vib

Out Vib

Shell Vib


RNMC Expert System vs. MillSlicer Fill Level Control

Green - Inlet, Blue - Outlet, Yellow - Shell, Pink - Toe Entropy, Olive - RPMs, Purple - Pressure, Teal - Feed

Soft/Fine Ore

Feed

Speed

Pressure

Toe Entr

In VibOut Vib

Shell Vib

Feed

Speed

Pressure

In Vib

Out Vib

Shell Vib


RNMC Material Blockage & Mill Speed Change Effect

Green - Inlet, Blue - Outlet, Yellow - Shell, Pink - Toe Entropy, Olive - RPMs, Purple - Pressure, Teal - Feed

Soft/Fine Ore

Blockage Start

Blockage End

Mill speed is increased to reduce the blockageOvershoot the end of blockage and so mill emptiesout too low.

Speed

Pressure

Toe Entropy

In VibOut Vib

Shell Vib

Feed

Feed is held constant (some variation due to feeder).

Mill Speed is significantly increased and then decreased.

Toe Entropy spike shows where liner damage is occurring.


MineralScan MillSlicer – Conclusions• Toe Entropy is an indicator of the “metal on metal” condition (balls striking liner)

• Polar plots can be used to identify material type and grinding efficiency• Soft ore (smooth even plot) vs. Hard Ore (energy in ball strike region only)

• For soft finer ore, the outlet vibration sensor should be used for auto-control

• For hard coarse ore, the shell based sensor is best for auto-control• Shell signal is several minutes ahead of bearing pressure (primary control)• It is the most responsive vibration signal of the three available

• When either shell or outlet signals are used for control, pressure should be used to adjust/change the auto-control set point based on the vibration signal i.e. if vibration current set point = 85%, pressure is too high, lower SP to 83%

• Feed should be kept at a constant rate and mill speed should be used for control• Fixed speed mills – control feed automatically with fill level signal

• Mill speed should only be changed in small increments infrequently- ~ 1 RPM change in the Mill RPM control room variable every 5

minutes

• Optimum performance occurs when all three vibration signals correlate in parallel • “what goes in = what goes out”

3701 nw 40 th terrace, #1, gainesville, florida 32606 usa mineralscan millslicer general overview by...

Documents

transmitter t sensor

shell sensor

ma signals

ma outputs

ma boards

main unit pc

main unit placement

th terrace