Can You Dig It? Advanced shovel-monitoring systems reduce downtime
Written by Enoch Chow
For many modern open-pit mines, shovels are one of the most critical
components in the production process. These multi-million-dollar
machines are the first to handle the material before transporting and
processing begins. Because of this, the shovel must be closely monitored
to avoid any unnecessary downtime and to ensure it is in peak operating
condition. Any unnecessary downtime can cost a mine thousands of
dollars per hour in lost production time.
One of the common causes of shovel downtime for many mines is worn or
missing shovel teeth or adaptors. Operating with worn teeth reduces the
performance of the shovel, resulting in increased energy usage, slower
operation and an increased likelihood of missing teeth or adaptors.
Replacing the worn teeth must be carefully planned as an unplanned
change-out can result in up to two hours of unexpected downtime. When
factoring in the opportunity cost of lost production, a 2009 case study
of an American copper mine determined that the total cost of an
unplanned change-out is US$41,368 — compared to US$3,000 for a planned
change-out.
In hard-rock mining, such as iron or copper ore mining, it is not
uncommon for the shovel teeth to go missing in normal operation. During
the digging cycle, the extreme forces can cause the teeth to break off
completely and become mixed with the loaded material. Big problems occur
when a load with a shovel tooth accidentally makes its way to the
crusher. Because the shovel teeth are made of a very durable metal, when
a tooth enters the crusher, it jams the crusher and can disable it for
hours or even days at a time. If the mine has no other primary crushers
or has little or no stockpile of crushed ore to feed the next stages of
production at the time, the mine production could be put to a complete
halt, which can result in millions of dollars in lost production time
for every occurrence.
To address issues with worn or missing shovel teeth or adaptors, a Canadian company, Motion Metrics International Corp.,
has developed two innovative tooth monitoring solutions: ToothMetrics
and WearMetrics. The ToothMetrics system constantly monitors the shovel
teeth with advanced image processing techniques and artificial
intelligence algorithms, and alerts the shovel operator when a shovel
tooth or adaptor is missing. Once detected, the tooth or adaptor can be
located and prevented from reaching the crusher. The WearMetrics system
automatically monitors the shovel tooth-wear and provides the status of
each shovel tooth by displaying the remaining length of the tooth
expressed as a percentage of the original length. This assists the mine
engineers in planning teeth replacements, and helps avoid any unplanned
change-outs. Both solutions share the same rugged embedded CPU platform
and hardware components, reducing the total cost of ownership for any
mine.
The system works by installing a rugged camera mounted on the boom of an
electric rope shovel or on the stick of a hydraulic face shovel. The
high-sensitivity, monochrome camera provides a clear view of the shovel
teeth directly to the embedded CPU, which is installed in the shovel
operator’s cab. Due to intense shock and vibration experienced by the
shovel during operation, Motion Metrics has designed shock-absorbing
camera brackets specifically for each different type of shovel,
including P&H and Bucyrus/CAT electric rope shovels, as well as
Komatsu, Liebherr, Terex/CAT, Hitachi and other makes of hydraulic
shovels.
The open-pit mining environment is also subject to a number of
environmental conditions such as dirt, dust and varying lighting
conditions, a key challenge for any mining system to deliver consistent
results. To counter lighting variations, a heavy-duty, high-intensity
LED light is installed alongside the camera to illuminate the shovel
teeth during night operations. Advanced artificial intelligence
algorithms continuously monitor the incoming video to exclude images
when the view of the teeth is blocked by dirt, dust or shadows and
select only optimal images for tooth analysis.
Building on this successful shovel-monitoring platform, Motion Metrics
has added the optional safety and collision avoidance components:
ViewMetrics and RadarMetrics. Due to the sheer size and vast blind spots
of mining shovels, the frequent and swift swinging action of the shovel
is a common concern for open-pit shovel operations as there is always a
risk of collision with other equipment or personnel working in close
proximity.
The ViewMetrics addition provides the shovel operator with three
additional wide-angle surveillance views around the shovel blind spots
in the left, right, and rear of the shovel for greater visibility.
RadarMetrics enhances the operator’s awareness even more by providing
intelligent proximity sensing and active feedback to the operator. This
addition seamlessly combines a strategically placed array of heavy-duty
pulsed radar sensors with the three surveillance views from ViewMetrics
to provide visual and audible alerts to the operator when an object
enters the shovel’s swing radius. Optional warning lights can also be
installed around the shovel to extend the warning to any nearby
equipment or personnel, providing an extra level of safety. This unique
patent-pending approach, according to Motion Metrics, is the “only
collision avoidance system for mining shovels [that] takes into account
the swing radius of the shovel when alerting the shovel operator.” This
additional level of intelligence helps eliminate unnecessary alarms that
would otherwise be distracting to the operator.
As real estate in the operator’s cab is limited, the company has managed
to integrate all five of the shovel monitoring solutions mentioned
above into a single embedded CPU platform and a 12-inch touchscreen
display installed in the cab.
The operator-oriented interface displays the shovel bucket camera view
from the ToothMetrics and WearMetrics systems, along with the three
surveillance views from the ViewMetrics systems. As an object enters the
shovel’s swing radius, RadarMetrics displays a graphical bird’s-eye
view of the shovel to indicate the direction and proximity of the
object, and also makes an audible alarm to grab the shovel operator’s
attention.
Motion Metrics is also a provider of payload monitoring systems for
large hydraulic mining shovels, such as the Terex/CAT RH340/400 and the
Komatsu PC8000. Many mines only have weighing systems on their haul
trucks, but this makes it difficult for the shovel operator to know when
a truck is being overloaded, since the weight will not be known before
the load is in the truck. Furthermore, many truck scales require the
truck to be in motion before the weighing system is able to provide an
accurate measurement. To prevent voiding the manufacturer’s warranty,
overloaded trucks must dump their load immediately, resulting in a
significant loss of productivity, as the same load will need to be
reworked and loaded a second time. On the other hand, underloaded trucks
requires the truck to make more trips, thereby increasing the mine’s
haulage cost per ton.
One of the key features of the LoadMetrics system is to provide the
bucket-by-bucket payload information directly to the shovel operator,
allowing the operator to determine whether dumping the current load will
overload or underload the haul truck. The system also provides helpful
warnings to the operator when the shovel is reaching its cylinder
extension or retraction limits. Repeated over-extending or retracting of
the shovel’s hydraulic cylinders can cause the cylinders to burst, thus
requiring premature replacements.
As a crucial element in open-pit mining operations, shovels should be
closely monitored to maximize productivity and minimize downtime. The
cost of any unnecessary downtime can easily cost the mine thousands or
millions of dollars in lost production time. To address many of these
challenges, Motion Metrics has developed a unique collection of shovel
monitoring solutions. Their proven systems have been installed in
various combinations in over 150 mining shovels and in over 30 mines
around the world since 2003.
Enoch Chow is the marketing manager with Motion Metrics International Corp. For more information, visit www.motionmetrics.com.
It’s a whole new world for maintenance and engineering technicians. The use of mobile computing devices is on the rise, replacing the traditional pen and clipboard. Is it right for your facility?
