Note: Descriptions are shown in the official language in which they were submitted.
CA 02642557 2008-10-31
APPARATUS AND METHOD FOR THE DETECTION AND REJECTION OF
METAL IN PARTICULATE MATERIAL
The present invention relates to an apparatus and method for the removal of
metal
inclusions in a flow of particulate material traveling along a conveyor.
BACKGROUND OF THE INVENTION
In the mining industry, it is common for mined materials such as coal, oil
sand,
etc. to contain a certain amount of metallic scrap such as bucket teeth,
crusher teeth,
tools, etc. (commonly referred to as "tramp metal") that can cause damage to
upstream
equipment. Oil sand is a type of bitumen deposit typically containing sand,
water and
very viscous oil (the bitumen). When the oil sand deposit is located
relatively close
below the ground surface, the oil sand is often extracted from the deposit by
mining. The
oil sand is mined by excavating down through the ground surface to where the
oil sand
deposit occurs and removing oil sand from the deposit with heavy machinery.
Typically, this removal of the oil sand from the deposit is done with some of
the
largest power shovels and dump trucks in the world, with the power shovels
removing
shovel-loads of oil sand from the deposit and loading the collected oil sand
onto
conveyors to be carried away for further processing.
The viscous bitumen tends to hold the sand and water together causing the
mined
oil sand to contain lumps and chunks, some of which can be quite large.
Because of the
size of some of these pieces of mined oil sand, the mined oil sand is
typically "pre-
crushed" by running it through a preliminary crusher to crush the pieces of
oil sand to a
suitable size for transport on a conveyor (i.e. conveyable size).
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The pre-crushed oil sand is then transported by conveyor to a slurry
preparation
unit as known in the art where the pre-crushed oil sand is further processed
to form an oil
sand and water slurry. One example of a slurry preparation unit is described
in Canadian
Patent Application No. 2,480,122, which unit comprises a series of roll
crushers spread
vertically throughout a portion of a slurry preparation tower. The slurry
preparation
tower typically uses gravity to move the oil sand through the tower.
Typically, each roll
crusher is made up of a number of crusher rolls spaced a set distance apart to
reduce the
size of large pieces of oil sand before the pieces of oil sand drop through
the crusher rolls
to the next roller crusher beneath or the bottom of the slurry preparation
tower. Each
successively lower roll crusher reduces the pieces of oil sand even smaller
until the oil
sand is fine enough to form a pumpable oil sand slurry.
At the same time the oil sand is passing though the different roll crushers,
heated
water is added to the oil sand to form it into a slurry. Typically, the stream
of oil sand
passing through the levels of roll crushers is sprayed with the heated water,
as it passes
down the tower. The mixing of this oil sand with the streams of hot water will
form the
eventual oil sand slurry, which is typically received in a pump box for
feeding the slurry
to a pump and pipeline system.
As long as only pre-crushed oil sand is being fed into a slurry preparation
unit
such as the aforedescribed slurry preparation tower, the slurry preparation
unit operates
properly. However, problems can occur when a piece of sizable metal (commonly
called
tramp metal) is present in the pre-crushed oil sand traveling along the
conveyor. This
tramp metal is often a piece of metal from machinery used earlier in the
process, such as
a piece of shovel tooth from the power shovel or a piece of crusher tooth from
the
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CA 02642557 2008-10-31
primary crusher. If this piece of tramp metal is large enough, when it is fed
into the
slurry preparation tower along with a portion of oil sand, the tramp metal can
damage or
even jam one of the roll crushers used in the slurry preparation tower. With
the roll
crushers damaged or jammed, the entire process has to be stopped while the
crusher rolls
are either repaired or the jam is located and the tramp metal removed. This
can lead to
lengthy outages to remove the object from the crusher rolls and affect repairs
if any
damage has occurred.
Unfortunately, this inclusion of tramp metal in the pre-crushed oil sand often
occurs quite frequently, with occurrences of tramp metal in a flow of pre-
crushed oil sand
having been seen as frequently as once per 12 hours shift.
Previously a complex system of screens has been used to locate and remove this
tramp metal from the process. However, these systems greatly complicated the
process
because they added a number of additional steps that could limit the amount of
oil sand
that was processed. Additionally, because of the conditions they were
operating under,
the screens often had relatively low operation lives, requiring frequent
repairs and
replacements. Most modern processes have completely removed the screens from
the
system and instead rely on metal detectors to locate pieces of tramp metal in
the oil sand.
Metal detectors are now commonly used to locate tramp metal in the flow of pre-
crushed oil sand along a conveyor. When the metal detector detects a piece of
tramp
metal in the oil sand, the metal detector either alerts an operator that metal
has been
detected in the flow of pre-crushed oil sand or sends a signal stopping the
conveyor and
preventing the tramp metal from being fed into the slurry preparation tower.
Once the
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conveyor is stopped, someone is sent out to locate the tramp metal and remove
it from the
pre-crushed oil sand.
However, the detection of tramp metals in the flow of oil sand is far simpler
than
the eventual locating and removal of the tramp metal from the oil sand once
the conveyor
is stopped. The oil sand on the conveyor can be 1-2 feet in depth, burying the
often
relatively small tramp metal. Additionally, because of the delay in time
between the
receipt of the alert from the metal detector and the stopping of the conveyor,
the tramp
metal will often vary in distance downstream from the metal detector, making
it guess
work for a person to figure out where along the length of pre-crushed oil sand
the tramp
metal lies. The conveyor carrying the oil sand can be hundreds of meters long
or more,
requiring a conveyor belt twice as long as the distance covered by the
conveyor. During
operation the conveyor belt is commonly driven at speeds between 3-4 meters
per second.
The significant weight of the belt, as well as its speed, results in the
moving belt having
significant inertia often requiring substantial force and a significant period
of time for the
conveyor belt to be decelerated and stopped. This can make the estimating of
the
position of the tramp metal buried in the oil sand on the belt less than
precise for the
human operators. Additionally, there are numerous factors with the conveyor,
such as
wear on bearing and the engine driving the conveyor belt, that can make the
deceleration
time to stop the belt vary over the life of the conveyor.
Not only does it take time to decelerate and halt the conveyor and then
restart and
accelerate the conveyor back up to the desired operating speed, because of the
force
required to decelerate and accelerate the conveyor, frequently stopping the
conveyor can
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increase the wear on the conveyor and its components, impacting the lifespan
of the
conveyor.
Additionally, the affects of halting the conveyor and stopping the flow of oil
sand
into the slurry preparation tower are not as simple as temporarily delaying
the process.
The processing of oil sand is commonly done as a continuous process. Stopping
the
conveyor can not only affect all later steps of the process, it can also
affect the quality of
the formed slurry. The slurry preparation tower requires a relatively
consistent feed rate
of oil sand to result in a high quality oil sand slurry having a consistent
density. It is
known that conditioning of oil sand slurry (e.g., release of bitumen flecks,
attachment of
bitumen flecks to air bubbles, etc.) is most efficient within a relatively
narrow density
range resulting from a proper ratio of oil sand to water in the slurry.
Interrupting the
supply of particulate oil sand to the slurry preparation tower can reduce the
quality of the
slurry, reducing the effectiveness of later process steps or even rendering a
slurry
unusable. In addition to the interruption, the time needed for the
deceleration of the
conveyor when the conveyor is being stopped to remove the tramp metal can
result in oil
sand slurry with a diminishing density as the flow rate of oil sand entering
the slurry
preparation tower decreases with the deceleration of the conveyor. When the
conveyor is
being sped up again, the time needed to accelerate the conveyor up to speed
can also
result in variations in the density of the resulting slurry.
There is therefore a need to remove pieces of tramp metal from a flow of
particulate material such as oil sand being moved on a conveyor without
halting the flow
of same for a significant period of time.
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CA 02642557 2008-10-31
SUMMARY OF THE INVENTION
In a first aspect, a system for rejecting a portion of non-metallic
particulate
material containing a piece of tramp metal is provided. The system comprises:
a
conveyor having a discharge end, the discharge end positioned to discharge
particulate
material from the conveyor to an intake opening; a metal detector positioned
adjacent to
the conveyor and upstream a travel distance from the discharge end; a
redirection device
provided at the discharge end of the conveyor, the redirection device
operative to allow
particulate matter discharging from the discharge end of the conveyor to enter
the intake
opening and, when activated, redirect particulate material discharged from the
discharge
end of the conveyor away from the intake opening; and a controller comprising
at least
one processor. The at least one processor is operative to: in response to
receiving a metal
detected signal from the metal detector, the metal detected signal indicating
that the metal
detector has detected a piece of metal in the particulate material traveling
along the
conveyor, determine a travel time for the piece of metal to reach the
discharge end of the
conveyor; and activate the redirection device to redirect particulate material
discharged
from the discharge end of the conveyor away from the intake opening at the
travel time.
In another aspect, a method for rejecting a portion of non-metallic
particulate
material containing a piece of tramp metal traveling along a conveyor
discharging to an
intake opening is provided. The method comprises: detecting a piece of metal
in
particulate material carried by the conveyor; determining a travel time
indicating when
the piece of metal will be discharged from the conveyor; and directing
particulate
material being discharged from the conveyor away from an intake opening for a
discharge time and then redirecting the particulate matter being discharged
from the
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CA 02642557 2008-10-31
conveyor to the intake opening after the discharge time, wherein the travel
time occurs
within the discharge time.
In another aspect, an apparatus for controlling a system to automatically
remove a
piece of tramp metal from particulate matter transported by a conveyor
discharging into
an intake opening is provided. The apparatus comprises: at least one processor
operative
to: in response to receiving a metal detector signal from a metal detector
indicating a
piece of metal has been detected a portion of particulate material traveling
along the
conveyor, determine a travel time for the piece of metal to reach a discharge
end of the
conveyor; and using the travel time, generate at least one signal and
transmitting the at
least one signal to a redirection device to cause the redirection device to
divert particulate
material discharging from the conveyor away from the intake opening for a
discharge
time.
BRIEF DESCRIPTION OF THE DRAWINGS
Referring to the drawings wherein like reference numerals indicate similar
parts
throughout the several views, several aspects of the present invention are
illustrated by
way of example, and not by way of limitation, in detail in the figures,
wherein:
Fig. I is a schematic illustration of a process for forming a pumpable oil
sand and
water slurry;
Fig. 2 is a schematic illustration of a system, in a first aspect, for
detecting a piece
of metal in particulate oil sand being carried along a conveyor and rejecting
a portion of
the particulate oil sand containing the piece of metal;
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Fig. 3 is a flowchart illustrating a method performed by an embodiment of a
controller;
Fig. 4 is a schematic illustration of a process for forming a pumpable oil
sand and
water slurry wherein a surge bin is used;
Fig. 5 is a schematic illustration of a system, in a further aspect, for
detecting a
piece of metal in particulate oil sand carried along a conveyor and rejecting
a portion of
the particulate oil sand containing the piece of metal, using a baffle wall;
Fig. 6 is a schematic illustration of the system shown in Fig. 5 with the
baffle wall
in a second position;
Fig. 7 is a schematic illustration of a system, in a further aspect, for
detecting a
piece of metal in particulate oil sand carried along a conveyor and rejecting
a portion of
the particulate oil sand containing the piece of metal, using a baffle wall
and chute that
operate in conjunction;
Fig. 8 is schematic illustration of the system of Fig. 7 in a rejection
position;
Fig. 9 is a schematic illustration of the system shown in Figs. 7 and 8
further
showing a collection zone where rejected oil sand is directed;
Fig. 10 is a schematic illustration of a system, in a further aspect, for
detecting a
piece of metal in particulate oil sand carried along a conveyor and rejecting
a portion of
the particulate oil sand containing the piece of metal, using a baffle wall;
Fig. 11 is schematic illustration of the system of Fig. 10 in a rejection
position;
and
Fig. 12 is a schematic illustration of a data processing system for use as a
controller in one aspect.
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DESCRIPTION OF VARIOUS EMBODIMENTS
The detailed description set forth below in connection with the appended
drawings is intended as a description of various embodiments of the present
invention
and is not intended to represent the only embodiments contemplated by the
inventor. The
detailed description includes specific details for the purpose of providing a
comprehensive understanding of the present invention. However, it will be
apparent to
those skilled in the art that the present invention may be practiced without
these specific
details.
Fig. I illustrates a process wherein oil sand is mined and then processed to
form
an oil sand slurry ready for hydrotransport (pumpable oil sand slurry). Oil
sand mined
from an oil sand deposit 2 by a power shovel 4 is fed into a hopper 6 of a
preliminary
conveyor 8. The preliminary conveyor 8 deposits a flow of the mined oil sand
into a
preliminary (or primary ) crusher 10 that reduces the size of the mined oil
sand to pieces
of conveyable size (pre-crushed oil sand). From the preliminary crusher 10 the
pre-
crushed oil sand is fed to a transport conveyor 310, using a loading conveyor
12, where
the particulate oil sand is transported along the transport conveyor 310 to a
discharge end
312 of the transport conveyor 310. At the discharge end 312 of the transport
conveyor
310, the pre-crushed oil sand is discharged through an intake opening 25 of a
surge bin
20, where it is eventually carried up a conveyor 110 and discharged into an
intake
opening 55 of the slurry preparation tower 50. The slurry preparation tower 50
takes the
flow of particulate oil sand discharging from a discharge end 112 of the
conveyor 110
and processes the flow of particulate oil sand to form an oil sand slurry.
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The length of the transport conveyor 310 will vary depending on the distance
of
the preliminary crusher 10 from the slurry preparation tower 50, but in many
cases the
transport conveyor 310 is hundreds of meters in length.
Fig. 2 is a schematic illustration of a system 100 in a first aspect. The
system 100
supplies a flow of particulate oil sand to the slurry preparation tower 50,
where the oil
sand will be further crushed and slurried with water to form a pumpable oil
sand slurry
for further processing. The system 100 comprises: a first conveyor 110; a
redirecting
device 105 having a second conveyor 120; a metal detector 140; and a control
device
150.
The first conveyor 110 transports a flow of particulate oil sand along a
length of
the first conveyor 110 towards a discharge end 112 of the first conveyor 110.
The
discharge end 112 is provided generally above an intake opening 55 of the
slurry
preparation tower 50.
The redirection device 105 comprises a second conveyor 120. The second
conveyor 120 is provided below the discharge end 112 so that a flow of
particulate oil
sand being discharged from the discharge end 112 of the first conveyor 110
lands on the
second conveyor 120. The second conveyor 120 is bi-directional so that the
second
conveyor 120 can be driven to carry material along the second conveyor 120
either in a
first direction, A, or a second direction, B. The second conveyor 120 is
positioned so that
particulate oil sand moved by the second conveyor 120 in the first direction,
A, and
discharged from a first end 122 of the second conveyor 120 will drop into the
intake
opening 55 of the slurry preparation tower 50. A second end 124 of the second
conveyor
120 is positioned so that particulate oil sand moved by the second conveyor
120 in the
CA 02642557 2008-10-31
second direction, B, and discharged from the second end 124 of the second
conveyor 120
will not fall into the intake opening 55 of the slurry preparation tower 50.
In an aspect,
the second end 124 of the second conveyor 120 is positioned so that oil sand
discharged
off of the second end 124 of the second conveyor 120 falls to a ground
surface, 40, beside
the slurry preparation tower 50.
The metal detector 140 is positioned along the first conveyor 110 a travel
distance, TD, from the discharge end 112 of the first conveyor 110. The metal
detector
140 can detect a piece of metal in the flow of particulate oil sand traveling
along the first
conveyor 110 past the metal detector 140.
The controller 150 is operatively connected to the metal detector 140 and the
second conveyor 120. The controller 150 could be a computer, a programmable
logic
controller (PLC), etc. operative to receive and transmit signals to control
the operation of
the system 100, such as the data processing device 800 shown in Fig. 12. The
data
processing device 800 includes a processor 810, system buses 820, memory 830
containing program instructions 840 and an I/O interface 850. The processor
810 is a
central processing unit that is typically microprocessor based to implement
the program
instructions 840 and control the operation of the data processing device 800.
The system
buses 820 allow the transmissions of digital signals between the various
components of
the data processing device 800. The memory 830 stores the operating system,
data
needed for the operation of the data processing device and the program
instructions 840.
Typically, the memory 830 will contain RAM for data and an EPROM or Rom for
storing the operating system and program instructions 840. The I/O interface
850 allows
for the connection to remote components to receive signals from remote
components and
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transmit signals to the remote components. A person skilled in the art will
appreciate that
the data processing system 800 will also include components, such as a power
supply, in
addition to those illustrated in Fig. 8.
Referring again to Fig. 2, the controller 150 is operatively connected to the
metal
detector 140 so that the controller 150 can receive a metal detected signal
from the metal
detector 140 when the metal detector 140 detects a piece of metal in the flow
of
particulate oil sand traveling along the first conveyor 110. The controller
150 is
operatively connected to the second conveyor 120 so that the controller 150
can control
the direction of the second conveyor 120. In an aspect, the controller 150 is
operatively
connected to a speed sensing device 160, such as a pulley mounted speed
encoder, to
obtain a speed of the first conveyor 110.
Fig. 3 is a flowchart illustrating a method 200 used by the controller 150, in
Fig.
2, to control the system 100. The method 200 comprises the steps of:
determining a
travel time 220; running a first timer 230; generating a reject signal 240;
running a
second timer 250; and triggering a resume signal 260.
Referring to Figs. 2 and 3, method 200 is started at step 210 when the
controller
150 receives a metal detected signal from the metal detector 140, indicating
that a piece
of metal has been detected in the flow of particulate oil sand traveling along
the first
conveyor 110.
At step 220, a travel time for the piece of metal detected by the metal
detector 140
to reach the discharge end 112 is determined. The travel time is determined
based on the
travel distance, TD, of the metal detector 140 from the discharge end 112 of
the first
conveyor 110 and the operating speed of the first conveyor 110. The travel
distance, TD,
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CA 02642557 2008-10-31
provides the distance the piece of metal will have to travel after it has
passed the metal
detector 140 before it reaches the discharge end 112 of the first conveyor
110. The
operating speed of the first conveyor 110 indicates the speed at which the
metal object
and the oil sand are being carried along the first conveyor 110. The operating
speed of
the first conveyor 110 could be obtained by the controller 150 by having the
first
conveyor 110 maintain a constant operating speed, however, because the travel
distance,
TD, can be quite long and the travel time relatively long (more than a minute)
it might be
desirable to obtain the operating speed of the conveyor belt 110 directly from
the speed
sensing device, 160, or from a device controlling the speed of the first
conveyor belt 110.
At step 230, the method 200 runs a first timer for a period of time equal to
the
travel time minus a buffer time.
At step 240, after the first timer has been run, a reject signal is generated
from the
controller 150 to the second conveyor 120. Step 240 is performed by the
controller 150
after the first timer is run. The first timer runs for a period of time equal
to the travel
time determined at step 220, for the piece of metal to reach the discharge end
112 of the
first conveyor 110 less a buffer time. The buffer time is a short period of
time used so
that a reject signal is generated by the controller 150, at step 240, before
the piece of
metal is discharged from the discharge end 112 of the first conveyor 110. The
buffer
time can allow enough time for the direction of operation of the second
conveyor 120 to
be reversed before the particulate oil sand containing the piece of metal
falls onto the
second conveyor 120, so that the second conveyor 120 is already operating in
the second
direction, B, by the time the piece of metal lands on the second conveyor 120.
The buffer
time can also be used to account for inaccuracies in the travel time
determined at step 220
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and delays in the transmission of the reject signal by increasing the buffer
timer to have
the reject signal transmitted earlier.
The travel time is use to determine when the piece of metal detected by the
metal
detector 140 has traveled along the first conveyor 110 to the discharge end
112 of the first
conveyor 110. Before the piece of metal is discharged off the discharge end
112 of the
first conveyor 110, the controller 130 transmits the reject signal to the
second conveyor
120.
When the second conveyor 120 receives the reject signal from the controller
150,
the second conveyor 120 reverses its direction of travel, moving material on
the second
conveyor 120 in the direction, B, carrying particulate oil sand discharged
onto the second
conveyor 120, from the first conveyor 110, off the second end 124 of the
second
conveyor 120 so that the oil sand does not fall into the intake opening 55 of
the slurry
preparation tower 50 and into the number of crusher rolls (not shown)
contained in the
slurry preparation tower 50.
At step 250, a second timer is run for a discharge time. The discharge time
will
be based on the length of the second conveyor 120 and the time required for
particulate
material landing on the second conveyor 120 from the first conveyor 110 to be
carried off
the second end 124 of the second conveyor 120 and how quickly the direction of
operation of the second conveyor 120 can be reversed. Typically, this time is
less than
one (1) minute with times of ten (10) seconds or less being possible to reduce
the time the
flow of particulate oil sand is stopped.
After the second timer has run for the discharge time, the method 200 proceeds
to
step 260 and a resume signal is transmitted. The controller 150 generates a
resume signal
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and transmits it to the second conveyor 120 causing the second conveyor 120 to
once
again change the direction and resume normal operation. The second conveyor
120
reverses the direction of travel from the second direction, B, back to the
first direction, A,
causing particulate oil sand discharged from the first conveyor 110 onto the
second
conveyor 120 to once again be discharged off the first end 122 of the second
conveyor
120 and into the intake opening 55 of the slurry preparation tower 50.
With step 260 completed, the system 100 is once again operating under normal
conditions delivering a flow of particulate oil sand to the slurry preparation
tower 50 and
the method 200 ends.
The method 200 will be invoked again if the metal detector 140 determines that
there is another piece of metal in the particulate oil sand traveling along
the first
conveyor 110.
In this manner, when the system 100 detects a piece of metal in the oil sand
traveling along the first conveyor 110, the system 100 approximates when the
piece of
metal will reach the discharge end 112 of the first conveyor 110 and be
discharged from
the first conveyor 110. Shortly before the piece of metal is discharged off
the first
conveyor 110, the direction of travel of the second conveyor 120 is reversed
so that
particulate oil sand on the second conveyor 120 is rejected from the system
100 by the
second conveyor 120. The reversal of direction of the second conveyor 120
discharges a
portion of particulate oil sand off the second end 124 of the second conveyor
120,
preventing the portion of particulate oil sand from entering the slurry
preparation tower
50. During this time, the piece of metal is discharged off the discharge end
112 of the
first conveyor 110, onto the second conveyor 120, where it is rejected from
the system.
CA 02642557 2008-10-31
After a relatively short period of time, sufficient for the portion of
particulate oil sand
containing the piece of metal to be discharged off the second conveyor 120,
the direction
of the second conveyor 120 is once again reversed and oil sand discharged from
the first
conveyor 110 to the second conveyor 120 is once again fed into the intake
opening 55 of
the slurry preparation tower 50.
Although a portion of the oil sand is rejected along with the piece of metal,
the
amount of time the flow of oil sand entering the slurry preparation tower 50
is halted is
relatively short, only the short period of time for the piece of metal to be
discharged off
the end of the first conveyor 110 onto the second conveyor 120, and then
discharged off
the second end 124 of the second conveyor 120. This short period of time is
based on
the length of the second conveyor 120. The shorter the second conveyor 120 and
the
faster the short conveyor 120 can change its direction of operation, the
shorter the short
period of time can be.
Because only the operation of the second conveyor 120 is affected, the first
conveyor 110 can be operated at a constant speed of operation throughout the
operation
of the method 200. Stopping the first conveyor 110 or even altering the speed
of first
conveyor 110 requires significantly more force and time than stopping or
altering the
direction of motion of the second conveyor 120 because of the greater inertia
of the
moving much larger conveyor belt of the first conveyor 110. Once the first
conveyor 110
is stopped, significant force is also required to get the first conveyor 110
back up to
operating speed. This can significantly impact the slurrying of the oil sand,
because the
slurry preparation is a continuous process. This continuous process is
affected by the
slowing down of the first conveyor 110 because this alters the flow rate of
particulate oil
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sand entering the slurry preparation tower 50, which can result in variations
in density of
the resulting oil sand slurry. The process is also interrupted for the
duration of the time
the first conveyor 110 is stopped because there is no particulate oil sand
entering the
slurry preparation tower 50 while the first conveyor 110 has stopped
operating. Finally,
starting the first conveyor 110 up again, after the interruption, requires the
first conveyor
110 to be accelerated back up to operating speed, which again requires some
time,
resulting in an uneven flow rate of particulate oil sand entering the slurry
preparation
tower 50 during this period, until the first conveyor 110 once again achieves
operating
speed.
Because the second conveyor 120 is significantly shorter than the first
conveyor
I 10, altering the speed of the second conveyor 120 is much easier, requiring
much less
force and time than the first conveyor 110 to bring the second conveyor 120 up
to
operating speed. Because the first conveyor 110 can be operated at a constant
operating
speed while the direction of the second conveyor 120 is reversed, the flow
rate of
particulate oil sand being discharged from the first conveyor 110 onto the
second
conveyor 120 remains constant, resulting in a more constant flowrate of
particulate oil
sand being delivered to the slurry preparation tower 50.
In some aspects, the surge bin 20 may not be used. Fig. 4 is a schematic
illustration of a variation of a process for taking mined oil sand and forming
an oil sand
slurry from the mined oil sand. This process is similar to the process shown
in Fig. 1,
with the exception that the surge bin 20 and the conveyor 110 are not used.
Instead, the
transport conveyor 310 discharges directly into the intake opening 55 of the
slurry
preparation tower 50. The system 100 shown in Fig. 2 can be used with the
transport
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conveyor 310, when the transport conveyor 310 is discharging directly into the
slurry
preparation tower 50. The metal detector 140 can be placed at a point along
the length of
the transport conveyor 310.
With the transport conveyor 310 discharging directly into the slurry
preparation
tower 50, the difference in size between the transport conveyor 310 and the
second
conveyor 120 is even greater. The transport conveyor 310 may be quite long in
aspects
where it has to carry particulate oil sand from a preliminary crushing stage
to the slurry
preparation tower 50, while the second conveyor 120 is much shorter than the
transport
conveyor 310. In some instances, the transport conveyor 310 can be five
hundred (500)
meters long or more, requiring more than a kilometer of conveyor belt. Because
of this,
the forces required to slow down and stop the transport conveyor 310 are much
greater
than those required to alter the direction of motion of the second conveyor
120.
Additionally, to once again get the transport conveyor 310 up to a desired
operating
speed after the transport conveyor 310 is stopped, significant force and time
is required to
accelerate the transport conveyor 310 back to the desired operating speed.
These
variations in speed and stopping time can significantly affect the slurrying
process.
Referring again to Fig. 1, even when the surge bin 20 and the conveyor 110 are
used, in some cases it may be desirable to reject a piece of metal from the
transport
conveyor 310, rather than the conveyor 110. Figs. 5 and 6 are schematic
illustrations of a
system 300 in a further aspect. Because the conveyor 310 does not discharge
directly
into the slurry preparation tower 50, but rather into the surge bin 20, system
300 has to be
modified from system 100, shown in Fig. 2 to take into account this
difference. The
system 300 comprises: a first conveyor 310; a redirection device 305,
including a second
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conveyor 320 and a baffle wall 370; a chute 375; a metal detector 340; and a
controller
150.
The first conveyor 310 has a discharge end 312. Particulate oil sand traveling
along the first conveyor 310 is discharged from the first conveyor 310 at the
discharge
end 312 of the first conveyor 310.
The redirection device 305 is provided at the discharge end 312 of the
conveyor
310. The second conveyor 320 is positioned below the discharge end 312 of the
first
conveyor 310. The second conveyor 320 is bi-directional so that it can be
operated in a
first direction, A, or a second direction, B. A first end 322 of the second
conveyor 320 is
positioned so that material discharged from the first end 322 of the second
conveyor 320,
when the second conveyor 320 is operating in the first direction, A, falls
into the intake
opening 25 of the surge bin 20. The second end 324 of the second conveyor 320
is
positioned so that material discharged from the second end 324 of the second
conveyor
320 is discharged to the chute 375 and the chute 375 directs the material away
from the
intake opening 25 of the surge bin 20.
The baffle wall 370 is positioned relative to the discharge end 312 and can be
moved between a first position and a second position. In the first position,
as shown in
Fig. 5, the baffle wall 370 allows particulate oil sand being discharged from
the discharge
end 312 of the first conveyor 310 to fall into the intake opening 25 of the
surge bin 20,
with any of the particulate oil sand falling on the second conveyor 320 being
carried in
the first direction, A, by the second conveyor 320, until the particulate oil
sand is
discharged off the first end 322 of the second conveyor 320 into the intake
opening 25 of
the surge bin 20. With the baffle wall 370 placed in the second position, as
shown in Fig.
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6, the baffle wall 370 deflects all of the particulate oil sand discharging
from the
discharge end 312 of the first conveyor 310 towards the second conveyor 320.
Typically, a hydraulic cylinder 372 is used to move the baffle wall 370
between
the first position and the second position.
The metal detector 340 is positioned a travel distance, TD, upstream from the
discharge end 312 of the first conveyor 310. The metal detector 340 can detect
a piece of
metal passing by the metal detector on the first conveyor 310.
The controller 150 is operatively connected to the metal detector 340, the
baffle
wall 370 (specifically the hydraulic cylinder 372), the second conveyor 320
and
optionally a speed determining device 360.
The controller 150 could be a computer, programmable logic controller, etc,
operative to control the operation of the system 300. The controller 150 is
operatively
connected to the metal detector 340 to receive metal detected signals from the
metal
detector 340 when the metal detector 340 detects a piece of metal passing the
metal
detector 340 on the first conveyor 310. The controller 150 is operatively
connected to the
hydraulic cylinder 372 and the second conveyor 320 so that the controller 150
can
transmit reject signals and resume signals to the hydraulic cylinder 372 and
the second
conveyor 320.
In response to receiving a reject signal from the controller 150, the second
conveyor 320 reverses its direction of operation from the first direction, A,
with the
second conveyor 320 discharging into the intake opening 25 of the surge bin
20, to the
second direction, B and the hydraulic cylinder 372 moves the baffle wall 370
from the
first position (shown in Fig. 5) to the second position (shown in Fig. 6). In
this manner,
CA 02642557 2008-10-31
particulate oil sand discharging from the first conveyor 310 is directed away
from the
intake opening 25 of the surge bin 20, so that a portion of the particulate
oil sand is
prevented from entering the surge bin 20 and continuing through the process.
In response to receive a resume signal, the second conveyor 320 reverses its
direction of operation back to the first direction, A, and the hydraulic
cylinder 372 moves
the baffle wall 370 back to the first position (shown in Fig. 5) and the
system 300
resumes normal operation, continuing to transport a flow of particulate oil
sand to the
slurry preparation tower 50.
Referring to Figs. 3, 5 and 6, the controller 150 uses the method 200
illustrated in
Fig. 3 to control the operation of the system 300 when a piece of metal is
detected by the
metal detector 340.
Method 200 begins at step 210 when controller 150 receives a metal detected
signal from the metal detector 340. At step 220, the controller 150 determines
a travel
time for the piece of metal to travel the travel distance, TD, along the first
conveyor 310
from the metal detector 340 to the discharge end 312.
Using the travel time determined at step 220, the controller 150 runs a first
timer
for a timer period equal to the travel time minus a buffer time. When the
first timer ends,
a reject signal is generated and transmitted to the hydraulic cylinder 372 and
the second
conveyor 320 at step 240.
Upon receiving the reject signal from the controller 150, the hydraulic
cylinder
372 is activated, moving the baffle wall 370 from the first position (as shown
in Fig. 5) to
the second position (as shown in Fig. 6). With the baffle wall 370 moved to
the second
position, particulate oil sand discharging from the discharge end 312 of the
first conveyor
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310 is deflected to the second conveyor 320. When the second conveyor 320
receives the
reject signal transmitted by the controller 150, the direction of operation of
the second
conveyor 320 is reversed from the first direction, A, to the second direction,
B, causing
particulate matter landing on the second conveyor 320 to be moved in the
second
direction, B, and off the second end 324 of the second conveyor 320 into the
chute 375.
After step 240, any particulate oil sand discharged from the discharge end 312
of
the first conveyor 310 is deflected by the baffle wall 370 to the second
conveyor 320.
Once on the second conveyor 320, the oil sand is carried to the second end 324
of the
second conveyor 320 where the chute 375 directs the particulate oil sand away
from the
intake opening 25 of the surge bin 20. In this manner, the system 300
temporarily directs
a portion of the particulate oil sand flow being discharged from the discharge
end 312 of
the first conveyor 310 away from the intake opening 25 of the surge bin 20,
removing
this portion of oil sand containing a piece of metal from the process of
creating an oil
sand slurry and preventing the piece of metal contained within the portion of
particulate
oil sand flow from carrying on through later steps in the process.
At step 240, the controller 150 runs a second timer for a discharge time and
after
the second timer has run for the discharge time, step 250 is performed and a
resume
signal transmitted by the controller 150 to the hydraulic cylinder 372 and the
second
conveyor 320. Upon receiving the resume signal, the hydraulic cylinder 372
moves the
baffle wall 370 from the second position (as show in Fig. 6), where the baffle
wall 370 is
deflecting the particulate matter discharging from the discharge end 312 of
the first
conveyor 310 towards the second conveyor 320, back to the first position (as
shown in
Fig. 5). The resume signal also causes the direction of operation of the
second conveyor
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320 to be once again reversed so that the direction of operation of the second
conveyor
320 is once again in the first direction, A. With the baffle wall 370 back in
the first
position and the second conveyor 320 moving in the first direction, A, the
system 300 is
back operating in a normal fashion and oil sand discharged from the first
conveyor 310 is
eventually moved through the process to be contained in an oil sand slurry.
After step
260, method 200 ends.
In this manner, system 300 allows a portion of oil sand containing a piece of
metal to be rejected from the system 300 preventing the metal from damaging
machinery
further downstream in the process.
Figs. 7 and 8 are schematic illustrations of a system 500 in a further aspect.
Similar to the system 300 shown in Figs. 5 and 6, system 500 comprises a first
conveyor
310 with a discharge end 312, a baffle wall 370, a metal detector 340, and a
controller
150. However, system 500 also contains a first chute 550 and a second chute
560. The
use of the first chute 550 in conjunction with the second chute 560 allows the
operation
of the system 500 without requiring the second conveyor 320 used in system 300
shown
in Figs. 5 and 6.
The first conveyor 310 supplies particulate oil sand to a surge bin 20 with
the
system 500 discharging particulate oil sand from the first conveyor 310 into
an intake
opening 25 of the surge bin 20 during normal operation.
The baffle wall 370 is positionable between a first position (shown in Fig.
7),
where the baffle wall 370 allows particulate oil sand being discharged from
the discharge
end 312 of the first conveyor 310 to enter into the intake opening 25 of the
surge bin 20
during normal operation of the system 500, and a second position (shown in
Fig. 8), with
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the baffle wall 370 deflecting the discharging particulate oil sand from the
first conveyor
310 away from the intake opening 25 of the surge bin 20.
The first chute 550 works in conjunction with the baffle wall 370 and is
positionable between a first position and a second position. In the first
position (shown in
Fig. 7), the first chute 550 is positioned to direct particulate oil sand
discharging from the
discharge end 312 of the first conveyor 310 into the intake opening 25 of the
surge bin
20. In the second position (shown in Fig. 8), the first chute 550 is
positioned to receive
particulate oil sand deflected by the baffle wall 370 and direct it to the
second chute 560.
The second chute 560 directs particulate oil sand away from the intake opening
25 of the
surge bin 20.
Typically, a first hydraulic cylinder 572 moves the baffle wall 370 between
the
first position and the second position and a second hydraulic cylinder 552
moves the first
chute 550 between the first position and the second position.
The controller 150 is operatively connected to the metal detector 340, the
baffle
wall 370 (specifically the first hydraulic cylinder 572), the first chute 550
(specifically
the second hydraulic cylinder 552) and, optionally, a speed determining device
360. The
controller 150 is operatively connected to the metal detector 340 to receive
metal
detected signals from the metal detector 340 when the metal detector 340
detects a piece
of metal passing the metal detector 340 on the first conveyor 310. The
controller 150 is
operatively connected to the first hydraulic cylinder 572 and the second
hydraulic
cylinder 552 so that the controller 150 can transmit reject signals and resume
signals to
the first hydraulic cylinder 572 and the second hydraulic cylinder 552.
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In response to a reject signal from the controller 150, the baffle wall 370 is
moved
from the first position to the second position, directing the flow of
particulate oil sand
discharging from the discharge end 312 of the first conveyor 310 away from the
intake
opening 25 of the surge bin 20. The first chute 550 is also moved to the
second position
in response to a reject signal from the controller 150 and in the second
position, the first
chute 550 acts in conjunction with the baffle wall 370 to route particulate
oil sand away
from the intake opening 25 of the surge bin 20.
In response to receiving a resume signal from the controller 150, the baffle
wall
370 is moved back to the first position and the first chute 550 is also moved
back to the
first position (as shown in Fig. 7).
Referring to Figs. 3, 7 and 8, the controller 150 uses the method 200
illustrated in
Fig. 3 to control the operation of the system 500 when a piece of metal is
detected by the
metal detector 340. The method 200 starts at step 210 when the controller 150
receives a
metal detected signal from the metal detector 340 and determines a travel time
at step 220
which it then uses to establish a time period for running a first timer at
step 230. After
the first timer is run at step 230, a reject signal is generated and sent to
the baffle wall 370
and the first chute 550 at step 240. A second timer is then run for a
discharge time at step
250, before a resume signal is generated and sent to the baffle wall 370 and
first chute
550 at step 260. The method 200 then ends.
In this manner, system 500 allows a portion of oil sand containing a piece of
metal to be rejected from the system 500 preventing the metal from damaging
machinery
further downstream in the process.
CA 02642557 2008-10-31
Fig. 9 is a schematic illustration of system the 500, with further components
added to address particulate oil sand that is being rejected from the system.
When the particulate oil sand is directed by the second chute 560 away from
the
intake opening 25 of the surge bin 20, in an aspect, the particulate oil sand
may fall
towards a support structure 610 that is suspending the discharge end 312 of
the first
conveyor 310 above the surge bin 20. To protect the support structure 610, a
number of
flexible baffles 630 are provided attached to the support structure 610. The
flexible
baffles 630 are typically made of a heavy material, such as rubber, and are
attached at a
top end 632 to the support structure 610, with a bottom end 634 of the
flexible baffles
630 freely hanging to absorb the force of any falling particulate material
striking the
flexible baffles 630.
A foundation 620 of the support structure 620 can be at least partially
surrounded
by a protecting wall 640 to protect the foundation 620 from falling
particulate material.
A collection zone 650 may be provided where the falling particulate matter
collects, with the collection zone 650 fenced off in one aspect to prevent
workers or other
people from entering the collection zone 650 and possibly being struck by
rejected oil
sand.
In some cases, it may be desirable to reject a portion or particulate oil sand
containing a piece of metal from a conveyor that does not end in either a
surge bin or
with a slurry preparation plant. In some cases it may be desirable to reject a
portion of
particulate oil sand containing a piece of metal from a transfer point between
two
different conveyors. Figs. 10 and 11 illustrate a system 700 for rejecting a
portion of
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particulate oil sand, containing a piece of metal, traveling along a first
conveyor 710,
instead of transferring the portion of particulate oil sand to a second
conveyor 720.
A redirection device 705 is provided that includes a baffle wall 770 and a
hydraulic cylinder 772. The baffle wall 770 is provided at a discharge end 712
of the first
conveyor 710. The baffle wall 770 is positionable between a first position,
where the
baffle wall 770 allows particulate oil sand being discharged from the
discharge end 712
of the first conveyor 710 to enter an intake opening 725 of the second
conveyor 720 (as
shown in Fig. 10) and a second position, where the baffle wall 770 deflects
particulate oil
sand discharging from the discharge end 712 of the first conveyor 710 away
from the
intake opening 725 of the second conveyor 720 (as shown in Fig. 11).
A metal detector 740 is provided along the first conveyor 710, a travel
distance,
TD, from the discharge end 712 of the first conveyor 710. The metal detector
740 is
operative to sense a piece of metal in particulate oil sand passing by the
metal detector
740 along the first conveyor 710.
A controller 150 is operatively connected to the metal detector 740, the
hydraulic
cylinder 772 and optionally a speed sensor 760, operative to determine the
speed of the
first conveyor 710 if the controller 150 is not connected to the system
controlling the
operation of the first conveyor 710.
The controller 150 is operatively connected to the metal detector 740, the
baffle
wall 770 (specifically the hydraulic cylinder 772) and optionally, a speed
determining
device 760. The controller 150 is operatively connected to the metal detector
740 to
receive metal detected signals from the metal detector 740 when the metal
detector 740
detects a piece of metal passing the metal detector 740 on the first conveyor
710. The
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controller 150 is operatively connected to the hydraulic cylinder 772 so that
the controller
150 can transmit reject signals and resume signals to the hydraulic cylinder
772.
In response to a reject signal from the controller 150, the baffle wall 770 is
moved
from the first position to the second position (as shown in Fig. 11),
directing the flow of
particulate oil sand discharging from the discharge end 712 of the first
conveyor 710
away from the intake opening 725 of the second conveyor 720. In response to a
resume
signal from the controller 150, the baffle wall 770 is moved back to the first
position (as
shown in Fig. 8).
Referring to Figs. 3, 10 and 11, the controller 150 uses the method 200
illustrated
in Fig. 3 to control the operation of the system 700 when a piece of metal is
detected by
the metal detector 740. The method 200 starts at step 210 when the controller
150
receives a metal detected signal from the metal detector 740 and determines a
travel time
at step 220 which it then uses to establish a time period for running a first
timer at step
230. After the first timer is run at step 230, a reject signal is generated
and sent to the
baffle wall 770 at step 240. A second timer is then run for a discharge time
at step 250,
before a resume signal is generated and sent to the baffle wall 770 at step
260. The
method 200 then ends.
In this manner, system 700 allows a portion of oil sand containing a piece of
metal to be rejected from the system 700 preventing the metal from damaging
machinery
further downstream in the process.
The previous description of the disclosed embodiments is provided to enable
any
person skilled in the art to make or use the present invention. Various
modifications to
those embodiments will be readily apparent to those skilled in the art, and
the generic
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principles defined herein may be applied to other embodiments without
departing from
the spirit or scope of the invention. Thus, the present invention is not
intended to be
limited to the embodiments shown herein, but is to be accorded the full scope
consistent
with the claims, wherein reference to an element in the singular, such as by
use of the
article "a" or "an" is not intended to mean "one and only one" unless
specifically so
stated, but rather "one or more". All structural and functional equivalents to
the elements
of the various embodiments described throughout the disclosure that are known
or later
come to be known to those of ordinary skill in the art are intended to be
encompassed by
the elements of the claims. Moreover, nothing disclosed herein is intended to
be
dedicated to the public regardless of whether such disclosure is explicitly
recited in the
claims.
29
