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25-007
Advancements in Leach Pad Control with Emerson Technologies
Trevor Riters
Emerson Automation Solutions, Chandler, AZ
ABSTRACT
Advancements in Emerson’s instrumentation technology
have brought value and efficiencies to the mining industry.
Some think of instrumentation as basic sensors and valves,
but with our solutions, we equip operators with real time,
accurate, and reliable data that they can use to operate
more effectively. Working with Caltrol, an Emerson Impact
Partner, we successfully engineered wireless skids for a leach
pad to provide precise measurement and control of raffinate
solution to many of the large mine sites in Arizona.
INTRODUCTION
In mining, heap leaching is a common process for recov-
ering valuable ores including copper, gold, and uranium
using a solution. The solution is used to extract desired
metals from an ore that has been crushed and stacked with
sulfuric acid being a common choice for extracting copper.
Heap leaching is commonly used because of the effective-
ness on such a large scale where each phase can stretch over
a mile wide as seen at sites like Freeport McMoran’s Safford
site in Arizona.
Working at such a large scale, efficiency is critical when
looking at raffinate (RAF) distribution across the field.
With too little solution running through the lines, you
miss out on valuable and recoverable ore. With too much,
you waste valuable solution and can create both safety and
environmental hazards if the additional liquid were to cause
a destabilizing event through corrosion and erosion or run
off site.
CURRENT PROCESS
While the leaching process is well understood and frequently
used in the mining industry, there are different ways the
flow of RAF is monitored and controlled. Many sites will
pump RAF to the leach pad and take measurements around
the pump where power is available, because measurement
is critical for monitoring the health of the pump. In this
scenario, the leach pad is usually manually monitored with
employees walking the leach pad to check for broken lines
and to report gauge pressures where they are installed. This
is to ensure distribution matches what is expected for the
acid consuming nature of the various ore qualities. With
the roughness of the leach pads and exposure to low grade
acids, daily monitoring of the pads creates the risks to the
safety of the employee, accuracy of the reporting, and an
overall efficiency of the operation.
The solution Emerson and Caltrol have created is an
instrumentation skid, or usually referred to in the field as
“skid.” This solution is a form of wireless control and moni-
toring of the RAF flow to different sections of the leach
pad through measurement instrumentation. The skids con-
sist of a wireless pressure transducer, wireless orifice plate
flow meter, and a pressure-regulating valve. Each piece of
instrumentation was specifically chosen because of its wire-
less capabilities circumventing the need to run expensive
conduit to each skid. In a paper published by Freeport
McMoRan, they installed 230 units per leach pad at their
Safford site. This provides them with over 1.2 million data
points per day at a 1-minute update rate per device. This is
sustained with
Emerson’s WirelessHART capabilities with the
3051SMV pressure transmitters working as a mesh network
to repeat signals back to a gateway. With the WirelessHART
signal, each device has a unique signature that can help cat-
egorize and sort the devices when the data is sent to the
control system. Repeaters are installed to strengthen the sig-
nal from the most remote devices. This solution has helped
improve the monitoring and control of raffinate flows to
leach pads (Figure 1).
With the data given from these processes, other effi-
ciencies have been identified. Using the data historian
25-007
Advancements in Leach Pad Control with Emerson Technologies
Trevor Riters
Emerson Automation Solutions, Chandler, AZ
ABSTRACT
Advancements in Emerson’s instrumentation technology
have brought value and efficiencies to the mining industry.
Some think of instrumentation as basic sensors and valves,
but with our solutions, we equip operators with real time,
accurate, and reliable data that they can use to operate
more effectively. Working with Caltrol, an Emerson Impact
Partner, we successfully engineered wireless skids for a leach
pad to provide precise measurement and control of raffinate
solution to many of the large mine sites in Arizona.
INTRODUCTION
In mining, heap leaching is a common process for recov-
ering valuable ores including copper, gold, and uranium
using a solution. The solution is used to extract desired
metals from an ore that has been crushed and stacked with
sulfuric acid being a common choice for extracting copper.
Heap leaching is commonly used because of the effective-
ness on such a large scale where each phase can stretch over
a mile wide as seen at sites like Freeport McMoran’s Safford
site in Arizona.
Working at such a large scale, efficiency is critical when
looking at raffinate (RAF) distribution across the field.
With too little solution running through the lines, you
miss out on valuable and recoverable ore. With too much,
you waste valuable solution and can create both safety and
environmental hazards if the additional liquid were to cause
a destabilizing event through corrosion and erosion or run
off site.
CURRENT PROCESS
While the leaching process is well understood and frequently
used in the mining industry, there are different ways the
flow of RAF is monitored and controlled. Many sites will
pump RAF to the leach pad and take measurements around
the pump where power is available, because measurement
is critical for monitoring the health of the pump. In this
scenario, the leach pad is usually manually monitored with
employees walking the leach pad to check for broken lines
and to report gauge pressures where they are installed. This
is to ensure distribution matches what is expected for the
acid consuming nature of the various ore qualities. With
the roughness of the leach pads and exposure to low grade
acids, daily monitoring of the pads creates the risks to the
safety of the employee, accuracy of the reporting, and an
overall efficiency of the operation.
The solution Emerson and Caltrol have created is an
instrumentation skid, or usually referred to in the field as
“skid.” This solution is a form of wireless control and moni-
toring of the RAF flow to different sections of the leach
pad through measurement instrumentation. The skids con-
sist of a wireless pressure transducer, wireless orifice plate
flow meter, and a pressure-regulating valve. Each piece of
instrumentation was specifically chosen because of its wire-
less capabilities circumventing the need to run expensive
conduit to each skid. In a paper published by Freeport
McMoRan, they installed 230 units per leach pad at their
Safford site. This provides them with over 1.2 million data
points per day at a 1-minute update rate per device. This is
sustained with
Emerson’s WirelessHART capabilities with the
3051SMV pressure transmitters working as a mesh network
to repeat signals back to a gateway. With the WirelessHART
signal, each device has a unique signature that can help cat-
egorize and sort the devices when the data is sent to the
control system. Repeaters are installed to strengthen the sig-
nal from the most remote devices. This solution has helped
improve the monitoring and control of raffinate flows to
leach pads (Figure 1).
With the data given from these processes, other effi-
ciencies have been identified. Using the data historian