The Problem
Our client experienced a significant water and debris contamination event
in theFixedBearing circuit of the SAG Mill.
The mill was immediately shut downto avoid bearing damage and the
contaminated oil was removed and new then oil introduced. Even so, there was concern that the circuits
still had potentially harmful debris and moisture present.
The lubricant removed was very dirty and saturated with water to 5000ppm, a
level of contamination that high would normally mean disposal/total loss, at a
cost of $20,000.
Lost production downtime at this mill is circa $1,000 per minute of
downtime as the two mills run in series potentially affecting other operations.
BioKem’s mobile VDOPS, on site and operational within hours of arrival, and conforming to all site requirements.
The Challenge
The rapid response solution was to
firstly remove residual water and particulate contamination in the in-service
SAG fixed bearing lube tank followed by cleaning and polishing of the bulk
contaminated oil. All tasks were completed
in an urgent timeframe to mitigate any potential damage to the gearbox and
trunnions.
Working with ISO 460 oil requiredraising the temperature from operating
temp of 47°C to >70°C to lower the viscosity to a workable 100cSt or less.
Filtration was to be conducted on in-service oil by way of kidney bypass
to the required standard in a reasonable timeframe. Access restrictions added to the complexity
of the job.
Solution
After initial contact and a phone consultation, BioKem mobilised the 50GPM
Vacuum Dehydration Oil Purification System (VDOPS) asset and engineering team
to the remote site in Queensland immediately. Site inductions, JSEA and documentation were
completed and BioKem were on site with all equipment within 30 hours.
The Mobile VDOPS is
equipped with 2 x 32 kW heaters, capable of heating 100L/min of this gear oil to
80°C, and drawing over 20” Hg of vacuum, for the most
efficient moisture dehydration and viscosity adjustments, without risk of
damaging the oil further.
The VDOPS is capable
of moisture removal and dissolved gases to below 50ppm, and ISO 4406
cleanliness to 13/12/10, with a β1000, 2.5 micron filtration.Equipped with 4m,
6m, and 12m hoses, we can access the most challenging locations. With 8 drain
points and a pressurised flushing system, we ensure no cross contamination from
previous jobs between different tanks and lubricants.
Fitted with 2” Camlocks,
Plugs & Caps for quick installation and adhering to a ‘NO SPILL’ policy.
To keep downtime and
revenue losses to a minimum, BioKem has developed operational procedures and
reporting systems, that maximiseefficiency and professionalism, setting the
industry standard.
In this case BioKem’s VDOPS not only purified the contaminated oil, but also
polished other in-service oil whilst the asset was available, offsetting the
cost of having BioKem onsite for the event and saving the customer money.
Purification Tasks
1.
SAG Mill Fixed Bearing Tank 6,000 L
2.
SAG Mill Floating Bearing Tank 4,500 L
3.
Outside Bulk Tank 5,000 L
4.
Polishing SAG Mill Floating Tank 4,500 L
5.
Ball Mill Floating Bearing Tank 4,500 L
Total Oil Purification Completed 24,500 L
1. SAG Mill Fixed Bearing Circuit
Tank 6000L
Starting ISO: 21/21/17 (out of spec)
After Purification
ISO: 16/15/12
Water Content: Not tested at start
Water Content after: <50ppm
VDOPS Purifying
Time: 26.9
Hrs
Comment: Client had sensibly drained
the contaminated oil and deployed a small centrifuge that helped. VDOPS further reduced the moisture and significant
larger debris was captured as shown.
2. SAG Mill Floating Bearing Circuit
Tank 4500L
Comment: Filtration was commenced on this oil however
the oil did not respond normally. It had
a very dark appearance and smelled ‘burnt’.
A sample was taken and this oil displayed a ‘cake of fines’.
Action: Client was advised to go offline drain this
tank as this contamination will cause significant wear.
A cake of fines is a very high
concentration of silt size particles and/or additive pack ingredients that
build up on the patch membrane obscuring all other contaminants. If the additive package breaks down in this
way and drops out of solution it is no longer performing its intended function. The oil that was removed was dehydrated and
left to be filtered over the next two weeks with depth filter media to remove
these sub-micron contaminants. Afterwards
an additive pack will be needed to restore this oil.
3.
Outside Bulk Tank 5000L
Operating outside and beyond ISO
4406 spec
Starting ISO: 23/22/17 (out of spec)
After Purification
ISO: 21/17/15
Water Content: 5000ppm (out of spec!)
Water Content after: 100ppm
VDOPS Purifying Time: 20.3 Hrs
Comments: A huge 25L of water was
removed and lubricant could then be returned to service. The image
shows the VDOPS collection chamber extracting water from the emulsified oil. No
free water was present.
Summary
In total 24,500L of oil was purified to better than target specification
in 114.2 Hrs.
The outcome was returning the plant to operation with a minimum of downtime
and without discarding any lubricant resources and associated costs. The client was so impressed with our response
service and professionalism; they have requested a regular 90 day service
agreement to manage the oil cleanliness.
|
Job#
|
Vol
|
ISO 4406
Start*
|
ISO 4406
Finish*
|
Hrs
|
Note
|
|
1
SAG Mill Fixed
|
6,000L
|
20.19.16
|
16.15.12
|
26.9
|
Excellent improvement in ISO4406
|
|
2
SAG Mill Floating
|
4,500L
|
-
|
-
|
33.5
|
Clean, however sub-micron ‘cake
of fines’ still present
|
|
3
Bulk Tank
|
5,000L
|
23.22.17
|
20.19.16
|
20.3
|
Highly emulsified oil, 25L of water
removed
|
|
4
SAG Mill Floating Polish
|
4,500L
|
20.19.16
|
-
|
12.3
|
Low level fines residue –
visually OK
|
|
5
Ball Mill Floating
|
4,500L
|
23.22.17
|
Await result
|
21.2
|
Oil was dry, however anticipate
significant improvement in cleanliness.
|
|
TOTAL
|
24,500L
|
-
|
-
|
114.2
|
|
Photo Essay
Comparison of SAG Floating oil contaminated with ‘cake of
fines’ (Left) darker pigment compared to SAG Fixed in-service oil after VDOPS
has cleaned it (Right).
Zero Spill Policy & Procedures
Advantage of pre-filtering the oil before the high value
glass fibre filter is subjected to this level of contamination!
Graph of how the ISO 4406 cleanliness will saw tooth with
the proposed deep filtration cycle over a rolling 90 days. The redline is the upper allowable limit.
Redundant Technology was onsite, deemed unsuitable and mothballed
