Note: Descriptions are shown in the official language in which they were submitted.
PRE-TREATMENT OF OIL SANDS FINE TAILINGS BY DEBRIS
REMOVAL
TECHNICAL FIELD
[0001] The technical field generally relates to the treatment of mine
tailings derived
from mining operations, and more particularly to techniques that can involve
screening
for removing coarse debris from oil sands fine tailings for example prior to
flocculation
and dewatering operations.
BACKGROUND
[0002] Oil sands tailings are generated from hydrocarbon extraction
process
operations that separate the valuable hydrocarbons from oil sand ore. There
are
various types of oil sands tailings, such as mature fine tailings (MFT) formed
in a
tailings pond. Tailings materials that have a high fines content can be
subjected to
dewatering operations, which can involve adding chemical additives such as
coagulants and/or flocculants and then separating solid minerals from the
water in the
tailings by supplying the treated tailings to a sub-aerial deposition area for
deposition in
thin lifts for drying, to a dewatering device, or to a pit for settling of the
mineral solids.
[0003] Prior to addition of a flocculant or other chemical agents to
the tailings
material, the fine tailings can be screened to remove coarse debris that can
cause
issues in downstream operations. For example, there exist methods and
apparatuses
for removing coarse debris from fine tailings prior to a flocculation and
dewatering
operation. However, there is still a need for enhancements in terms of methods
and
screening apparatuses for coarse debris removal from tailings streams.
SUMMARY
[0004] The present disclosure provides processes, systems, devices
and
techniques for pre-treating an aqueous suspension including fine solid
particles and
coarse debris, in order to remove coarse debris prior to further treatments.
The present
techniques are particularly claimed and described with respect to an aqueous
suspension derived from mining operations and referred to as mining tailings,
including
oil sands fine tailings, such as mature fine tailings (M FT).
[0005] In one aspect, there is provided pre-treatment screening
assembly
comprising a spillbox feed tank comprising a bottom wall and side walls
extending
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upwardly from the bottom wall, thereby defining a tank cavity, a tailings
inlet provided in
the bottom wall for receiving a tailings fluid flow into the tank cavity, and
a screening
device having a screening surface receiving the tailings fluid flow from the
spillbox feed
tank, the screening surface being configured to allow material with a
predetermined
size that is included in the tailings fluid flow to flow through the screening
surface and
separate coarse debris from the tailings fluid flow, thereby separating the
tailings fluid
into a coarse debris fraction and a screened tailings fluid; and a collector
body
arranged below the screening surface of the screening device to receive the
screened
tailings fluid, the collector body comprising side walls and a bottom wall
defining
together a collecting cavity.
[0006] In another aspect, there is provided pre-treatment screening
assembly
comprising a spillbox feed tank comprising a bottom wall and side walls
extending
upwardly from the bottom wall, thereby defining a tank cavity, and a tailings
inlet
provided above a portion of the tank cavity for discharging downwardly a
tailings fluid
flow into the tank cavity; a screening device having a screening surface
receiving the
tailings fluid flow from the spillbox feed tank, the screening surface being
configured to
allow material with a predetermined size that is included in the tailings
fluid flow to flow
through the screening surface and separate coarse debris from the tailings
fluid flow,
thereby separating the tailings fluid into a coarse debris fraction and a
screened tailings
fluid; and a collector body arranged below the screening surface of the
screening
device to receive the screened tailings fluid, the collector body comprising
side walls
and a bottom wall defining together a collecting cavity.
[0007] In another aspect, there is provided pre-treatment screening
assembly
comprising a spillbox feed tank comprising a bottom wall and side walls
extending
upwardly from the bottom wall, thereby defining a tank cavity, and a tailings
inlet
provided substantially centrally in the bottom wall for receiving a tailings
fluid flow into
the tank cavity; a screening device having a screening surface receiving the
tailings
fluid flow spilling from the spillbox feed tank, the screening surface being
configured to
allow material with a predetermined size that is included in the tailings
fluid flow to flow
through the screening surface and separate coarse debris from the tailings
fluid flow,
thereby separating the tailings fluid into a coarse debris fraction and a
screened tailings
fluid; and a collector body arranged below the screening surface of the
screening
device to receive the screened tailings fluid.
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[0008] In another aspect, there is provided a pre-treatment screening
assembly
comprising a spillbox feed tank comprising a bottom wall and side walls
extending
upwardly from the bottom wall, thereby defining a tank cavity, and a tailings
inlet
comprising a distribution pipe extending substantially horizontally above a
portion of the
tank cavity for discharging downwardly a tailings fluid flow into the tank
cavity; a
screening device having a screening surface receiving the tailings fluid flow
from the
spillbox feed tank, the screening surface being configured to allow material
with a
predetermined size that is included in the tailings fluid flow to flow through
the
screening surface and separate coarse debris from the tailings fluid flow,
thereby
separating the tailings fluid into a coarse debris fraction and a screened
tailings fluid;
and a collector body arranged below the screening surface of the screening
device to
receive the screened tailings fluid.
[0009] In another aspect, there is provided a pre-treatment screening
assembly
comprising a spillbox feed tank comprising a bottom wall and side walls
extending
upwardly from the bottom wall, thereby defining a tank cavity, a tailings
inlet for
receiving a tailings fluid flow into the tank cavity, and an overflow weir
extending
outwardly from an upper portion of the tank cavity; a screening device having
a
screening surface receiving the tailings fluid flow spilling over the overflow
weir of the
spillbox feed tank, the screening surface being configured to allow material
with a
predetermined size that is included in the tailings fluid flow to flow through
the
screening surface and separate coarse debris from the tailings fluid flow,
thereby
separating the tailings fluid into a coarse debris fraction and a screened
tailings fluid;
and a collector body arranged below the screening surface of the screening
device to
receive the screened tailings fluid; wherein a width of the overflow weir is
smaller than
a width of the screening surface.
[0010] In another aspect, there is provided a pre-treatment screening
assembly
comprising a spillbox feed tank comprising a bottom wall and side walls
extending
upwardly from the bottom wall, thereby defining a tank cavity, a tailings
inlet for
receiving a tailings fluid flow into the tank cavity, and an adjustable valve
configured to
cooperate with the tailings inlet in response to the level measured by the
level sensor;
a screening device having a screening surface receiving the tailings fluid
flow from the
spillbox feed tank, the screening surface being configured to allow material
with a
predetermined size that is included in the tailings fluid flow to flow through
the
screening surface and separate coarse debris from the tailings fluid flow,
thereby
separating the tailings fluid into a coarse debris fraction and a screened
tailings fluid; a
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collector body arranged below the screening surface of the screening device to
receive
the screened tailings fluid, the collector body comprising side walls and a
bottom wall
defining together a collecting cavity; and a level sensor for measuring a
tailings fluid
level in one of the tank cavity and the collecting cavity.
[0011] In another aspect, there is provided a pre-treatment screening
assembly
comprising a spillbox feed tank comprising a bottom wall and side walls
extending
upwardly from the bottom wall, thereby defining a tank cavity, a tailings
inlet for
receiving a tailings fluid flow into the tank cavity, and an overflow weir
extending
outwardly from an upper portion of the tank cavity; a screening device
comprising a
screening surface receiving the tailings fluid flow spilling over the overflow
weir of the
spillbox feed tank, the screening surface being configured to allow material
with a
predetermined size that is included in the tailings fluid flow to flow through
the
screening surface and separate coarse debris from the tailings fluid flow,
thereby
separating the tailings fluid into a coarse debris fraction and a screened
tailings fluid,
and a cleaning device to remove the coarse debris from the screening surface;
and a
collector body arranged below the screening surface of the screening surface
to
receive the screened tailings fluid.
[0012] In another aspect, there is provided a pre-treatment screening
assembly
comprising a screening device comprising a screening surface receiving a
tailings fluid
flow, the screening surface being configured to allow material with a
predetermined
size that is included in the tailings fluid flow to flow through the screening
surface and
separate coarse debris from the tailings fluid flow, thereby separating the
tailings fluid
into a coarse debris fraction and a screened tailings fluid, the screening
surface
defining a first adjustable inclination angle with a horizontal direction; and
a collector
body arranged below the screening surface of the screening surface to receive
the
screened tailings fluid.
[0013] In another aspect, there is provided a pre-treatment screening
assembly
comprising a screening device comprising a screening surface receiving a
tailings fluid
flow, the screening surface being configured to allow material with a
predetermined
size that is included in the tailings fluid flow to flow through the screening
surface and
separate coarse debris from the tailings fluid flow, thereby separating the
tailings fluid
into a coarse debris fraction and a screened tailings fluid, and a mechanical
cleaning
device configured to mechanically remove the coarse debris from the screening
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surface; and a collector body arranged below the screening surface of the
screening
surface to receive the screened tailings fluid.
[0014] In another aspect, there is provided a pre-treatment screening
assembly
comprising a screening device comprising a screening surface receiving a
tailings fluid
flow, the screening surface being configured to allow material with a
predetermined
size that is included in the tailings fluid flow to flow through the screening
surface and
separate coarse debris from the tailings fluid flow, thereby separating the
tailings fluid
into a coarse debris fraction and a screened tailings fluid, and a cleaning
device
configured to remove the coarse debris from the screening surface; a collector
body
arranged below the screening surface of the screening surface to receive the
screened
tailings fluid; and a debris collection bin arranged under or close to the
screening
device to collect the coarse debris removed from the screening surface.
[0015] In another aspect, there is provided a pre-treatment screening
assembly
comprising a spillbox feed tank comprising a bottom wall and side walls
extending
upwardly from the bottom wall, thereby defining a tank cavity, a tailings
inlet for
receiving a tailings fluid flow into the tank cavity, and an overflow weir
extending
outwardly from an upper portion of the tank cavity; a screening device
comprising a
screening surface receiving the tailings fluid flow spilling over the overflow
weir of the
spillbox feed tank, the screening surface being configured to allow material
with a
predetermined size that is included in the tailings fluid flow to flow through
the
screening surface and separate coarse debris from the tailings fluid flow,
thereby
separating the tailings fluid into a coarse debris fraction and a screened
tailings fluid;
and a collector body arranged below the screening surface of the screening
device and
having a collecting cavity to receive the screened fluid, the collector body
comprising a
discharge opening formed in a bottom portion of the collector body for
collecting and
easily removing debris that build up in the collector body.
[0016] In another aspect, there is provided a pre-treatment screening
assembly
comprising a screening device comprising a screening surface receiving a
tailings fluid
flow, the screening surface being configured to allow material with a
predetermined
size that is included in the tailings fluid flow to flow through the screening
surface and
separate coarse debris from the tailings fluid flow, thereby separating the
tailings fluid
into a coarse debris fraction and a screened tailings fluid; and a collector
body
arranged below the screening surface of the screening device and comprising a
bottom
wall and side walls extending from the bottom wall, thereby defining a
collecting cavity
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to receive the screened fluid, a discharge opening formed in a bottom portion
of the
collector body for collecting and easily removing debris that build up in the
collector
body, the side walls converging toward the discharge opening.
[0017] In another aspect, there is provided a pre-treatment screening
assembly
comprising a screening device comprising a screening surface receiving a
tailings fluid
flow, the screening surface being configured to allow material with a
predetermined
size that is included in the tailings fluid flow to flow through the screening
surface and
separate coarse debris from the tailings fluid flow, thereby separating the
tailings fluid
into a coarse debris fraction and a screened tailings fluid; and a collector
body
arranged below the screening surface of the screening device and having a
collecting
cavity to receive the screened fluid, the collector body comprising a
deflector plate
arranged in the collecting cavity.
[0018] In another aspect, there is provided a pre-treatment screening
assembly
comprising a plurality of spillbox feed tanks, each spillbox feed tank
comprising a
bottom wall and side walls extending upwardly from the bottom wall, thereby
defining a
tank cavity, a tailings inlet for receiving a tailings fluid flow into the
tank cavity, an
overflow weir extending outwardly from an upper portion of the tank cavity,
and an
adjustable valve configured to cooperate with the tailings inlet; a plurality
of screening
devices, each screening device having a screening surface receiving the
tailings fluid
flow spilling over the overflow weir of one of the spillbox feed tanks, the
screening
surface being configured to allow material with a predetermined size that is
included in
the tailings fluid flow to flow through the screening surface and separate
coarse debris
from the tailings fluid flow, thereby separating the tailings fluid into a
coarse debris
fraction and a screened tailings fluid; and a collector body arranged below
the
screening surface of the screening devices having a collecting cavity to
receive the
screened tailings fluids of the plurality of screening devices; the adjustable
valves of
the spillbox feed tanks being adjusted for the different spillbox feed tanks
to have a
substantially similar outlet flow.
[0019] In another aspect, there is provided a pre-treatment screening
assembly
comprising a spillbox feed tank comprising a bottom wall and side walls
extending
upwardly from the bottom wall, thereby defining a tank cavity, a tailings
inlet for
receiving a tailings fluid flow into the tank cavity, and a screening device
having a
screening surface receiving the tailings fluid flow from the spillbox feed
tank, the
screening surface being configured to allow material with a predetermined size
that is
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included in the tailings fluid flow to flow through the screening surface and
separate
coarse debris from the tailings fluid flow, thereby separating the tailings
fluid into a
coarse debris fraction and a screened tailings fluid; a collector body
arranged below the
screening surface of the screening device to receive the screened tailings
fluid; and a
frame to which the spillbox feed tank, the screening device and the collector
body are
mounted, for the spillbox feed tank, the screening device and the collector
body to be
spaced apart from a ground surface supporting the frame.
[0020] In another aspect, there is provided a pre-treatment screening
assembly
comprising a plurality of spillbox feed tanks, each spillbox feed tank
comprising a
bottom wall and side walls extending upwardly from the bottom wall, thereby
defining a
tank cavity, a tailings inlet for receiving a tailings fluid flow into the
tank cavity, and an
overflow weir extending outwardly from an upper portion of the tank cavity; at
least two
screening devices, each screening device defining a longitudinal direction and
having
two opposed longitudinal ends, said at least two screening devices extending
side to
side substantially parallel, and each screening device having a screening
surface
receiving the tailings fluid flow spilling over the overflow weir of one of
the spillbox feed
tanks, the screening surface being configured to allow material with a
predetermined
size that is included in the tailings fluid flow to flow through the screening
surface and
separate coarse debris from the tailings fluid flow, thereby separating the
tailings fluid
into a coarse debris fraction and a screened tailings fluid; an access
platform extending
along the screening devices at one of their longitudinal ends; and a collector
body
arranged below the screening surface of the screening devices having a
collecting
cavity to receive the screened tailings fluids.
[0021] In another aspect, there is provided a pre-treatment site
comprising a pre-
treatment screening assembly according to the present disclosure; an inlet
line fluidly
connected to the pre-treatment screening assembly to discharge a tailings
fluid flow
onto the screening surface of the screening device; and a discharge line
fluidly
connected to the collector body for downstream treatment operations of the
screened
tailings fluid.
[0022] In another aspect, there is provided a process for screening
coarse debris
from a tailings fluid flow coming from an inlet line, the process comprising
providing the
tailings fluid flow to a pre-treatment screening assembly comprising a
spillbox feed tank
having a bottom wall and side walls extending upwardly from the bottom wall,
thereby
defining a tank cavity, a screening device and a collector body; connecting
the inlet line
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to a tailings inlet formed in the bottom wall of the spillbox feed tank so as
to form in the
tank cavity a substantially vertical tailings fluid inlet flow; filling the
tank cavity of the
spillbox feed tank with the tailings fluid flow; discharging a tailings fluid
outlet flow from
the tank cavity onto the screening device, the screening device having a
screening
surface configured to allow material with a predetermined size that is
included in the
tailings fluid flow to flow through the screening surface and separate coarse
debris from
the tailings fluid flow, thereby separating the tailings fluid into a coarse
debris fraction
and a screened tailings fluid; and collecting the screened tailings fluid into
the collector
body
[0023] In another aspect, there is provided a process for screening
coarse debris
from a tailings fluid flow coming from an inlet line, the process comprising
providing the
tailings fluid flow to a pre-treatment screening assembly comprising a
spillbox feed tank
having a bottom wall and side walls extending upwardly from the bottom wall,
thereby
defining a tank cavity, a screening device and a collector body; connecting
the inlet line
to a tailings inlet provided above a portion of the tank cavity for
discharging downwardly
the tailings fluid flow into the tank cavity; filling the tank cavity of the
spillbox feed tank
with the tailings fluid flow; discharging a tailings fluid outlet flow from
the tank cavity
onto the screening device, the screening device having a screening surface
configured
to allow material with a predetermined size that is included in the tailings
fluid flow to
flow through the screening surface and separate coarse debris from the
tailings fluid
flow, thereby separating the tailings fluid into a coarse debris fraction and
a screened
tailings fluid; and collecting the screened tailings fluid into the collector
body.
[0024] In another aspect, there is provided a process for screening
coarse debris
from a tailings fluid flow coming from an inlet line, the process comprising
providing the
tailings fluid flow to a pre-treatment screening assembly comprising a
spillbox feed tank
with a tank cavity, a screening device and a collector body; connecting the
inlet line to
a tailings inlet formed in the spillbox feed tank; filling the tank cavity of
the spillbox feed
tank with the tailings fluid flow; discharging a tailings fluid outlet flow
from the tank
cavity onto the screening device, the screening device having a screening
surface
configured to allow material with a predetermined size that is included in the
tailings
fluid flow to flow through the screening surface and separate coarse debris
from the
tailings fluid flow, thereby separating the tailings fluid into a coarse
debris fraction and a
screened tailings fluid; collecting the screened tailings fluid into the
collector body; and
removing the coarse debris from the screening surface.
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[0025] In another aspect, there is provided a process for screening
coarse debris
from a tailings fluid flow coming from an inlet line and going into a
discharge line, the
process comprising providing the tailings fluid flow to a pre-treatment
screening
assembly comprising a spillbox feed tank with a tank cavity, a screening
device and a
collector body having a discharge outlet connected to the discharge line;
connecting
the inlet line to a tailings inlet formed in the spillbox feed tank; filling
the tank cavity of
the spillbox feed tank with the tailings fluid flow; discharging a tailings
fluid outlet flow
from the tank cavity onto the screening device, the screening device having a
screening surface configured to allow material with a predetermined size that
is
included in the tailings fluid flow to flow through the screening surface and
separate
coarse debris from the tailings fluid flow, thereby separating the tailings
fluid into a
coarse debris fraction and a screened tailings fluid; collecting the screened
tailings fluid
into the collector body; and deflecting the screened tailings fluid inlet flow
filling the
collector body from the discharge outlet.
[0026] In another aspect, there is provided a process for screening
coarse debris
from a tailings fluid flow coming from an inlet line and going into a
discharge line, the
process comprising providing the tailings fluid flow to a pre-treatment
screening
assembly comprising a spillbox feed tank with a tank cavity, a screening
device and a
collector body having a discharge outlet connected to the discharge line;
connecting
the inlet line to a tailings inlet formed in the spillbox feed tank; filling
the tank cavity of
the spillbox feed tank with the tailings fluid flow; discharging a tailings
fluid outlet flow
from the tank cavity onto the screening device, the screening device having a
screening surface configured to allow material with a predetermined size that
is
included in the tailings fluid flow to flow through the screening surface and
separate
coarse debris from the tailings fluid flow, thereby separating the tailings
fluid into a
coarse debris fraction and a screened tailings fluid; collecting the screened
tailings fluid
into the collector body; and removing debris building up in the collector
body.
[0027] In another aspect, there is provided a process for screening
coarse debris
from a tailings fluid flow coming from an inlet line, the process comprising
providing the
tailings fluid flow to a pre-treatment screening assembly comprising at least
two
spillbox feed tanks having each a tank cavity with an upper portion and an
overflow
weir extending outwardly from the upper portion of the tank cavity, the pre-
treatment
screening assembly further comprising a screening device and a collector body;
connecting the inlet line to a tailings inlet formed in each of the spillbox
feed tanks;
filling each tank cavity of the spillbox feed tanks with the tailings fluid
flow for the
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tailings fluid flow to reach an overflow weir of each of the spillbox feed
tanks;
discharging a tailings fluid outlet flow over the overflow weir of the tank
cavity onto the
screening device, the screening device having a screening surface configured
to allow
material with a predetermined size that is included in the tailings fluid flow
to flow
through the screening surface and separate coarse debris from the tailings
fluid flow,
thereby separating the tailings fluid into a coarse debris fraction and a
screened tailings
fluid; collecting the screened tailings fluid into the collector body; and
adjusting the
outflow rate of at least one of the tailings fluid outlet flow for the
different spillbox feed
tanks to have a substantially similar outlet flow rate.
[0028] In another aspect, there is provided a pre-treatment screening
assembly
comprising a spillbox feed tank defining a tank cavity and comprising a bottom
wall,
and a tailings inlet provided in the bottom wall for receiving a tailings
fluid flow into the
tank cavity; a screening device having a screening surface receiving the
tailings fluid
flow from the spillbox feed tank, the screening surface being configured to
allow
material smaller than a predetermined size that is included in the tailings
fluid flow to
flow through the screening surface and separate coarse debris larger than or
equal to
the predetermined size from the tailings fluid flow, thereby separating the
tailings fluid
into a coarse debris fraction and a screened tailings fluid; and a collector
body
arranged below the screening surface of the screening device to receive the
screened
tailings fluid.
[0029] In another aspect, there is provided pre-treatment screening
assembly
comprising a spillbox feed tank defining a tank cavity and comprising a
tailings inlet
provided above an upper portion of the tank cavity for discharging downwardly
a
tailings fluid flow into the tank cavity; a screening device having a
screening surface
receiving the tailings fluid flow from the spillbox feed tank, the screening
surface being
configured to allow material smaller than a predetermined size that is
included in the
tailings fluid flow to flow through the screening surface and separate coarse
debris
larger than or equal to the predetermined size from the tailings fluid flow,
thereby
separating the tailings fluid into a coarse debris fraction and a screened
tailings fluid;
and a collector body arranged below the screening surface of the screening
device to
receive the screened tailings fluid.
[0030] In another aspect, there is provided pre-treatment screening
assembly
comprising a spillbox feed tank defining a tank cavity and comprising a
tailings inlet for
receiving a tailings fluid flow into the tank cavity; an adjustable inlet
valve configured to
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adjust the tailings fluid inlet flow in the spillbox feed tank; a screening
device having a
screening surface receiving the tailings fluid flow from the spillbox feed
tank, the
screening surface being configured to allow material smaller than a
predetermined size
that is included in the tailings fluid flow to flow through the screening
surface and
separate coarse debris larger than or equal to the predetermined size from the
tailings
fluid flow, thereby separating the tailings fluid into a coarse debris
fraction and a
screened tailings fluid; a collector body arranged below the screening surface
of the
screening device to receive the screened tailings fluid and defining a
collecting cavity;
and one or more level sensors for measuring a tailings fluid level in the tank
cavity
and/or the collecting cavity. The adjustable inlet valve is configured to
adjust the
tailings fluid inlet flow in the spillbox feed tank in response to the
tailings fluid level
measured by the one or more level sensors.
[0031] In another aspect, there is provided a pre-treatment screening
assembly
comprising a spillbox feed tank defining a tank cavity and comprising a
tailings inlet for
receiving a tailings fluid flow into the tank cavity; a screening device
comprising a
screening surface receiving the tailings fluid flow from the spillbox feed
tank, the
screening surface being configured to allow material smaller than a
predetermined size
that is included in the tailings fluid flow to flow through the screening
surface and
separate coarse debris larger than or equal to the predetermined size from the
tailings
fluid flow, thereby separating the tailings fluid into a coarse debris
fraction and a
screened tailings fluid, and a cleaning device to remove the coarse debris
from the
screening surface; and a collector body arranged below the screening surface
of the
screening device to receive the screened tailings fluid.
[0032] In another aspect, there is provided pre-treatment screening
assembly
comprising a screening device comprising a screening surface receiving a
tailings fluid
flow, the screening surface being configured to allow material smaller than a
predetermined size that is included in the tailings fluid flow to flow through
the
screening surface and separate coarse debris larger than or equal to the
predetermined size from the tailings fluid flow, thereby separating the
tailings fluid into
a coarse debris fraction and a screened tailings fluid, the screening surface
defining an
inclination angle with respect to horizontal; a cleaning device configured to
cooperate
with the screening device to adjust the inclination angle when the screening
device is
configured into a cleaning mode; and a collector body arranged below the
screening
surface of the screening device to receive the screened tailings fluid.
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[0033] In another aspect, there is provided pre-treatment screening
assembly
comprising a screening device comprising a screening surface receiving a
tailings fluid
flow, the screening surface being configured to allow material smaller than a
predetermined size that is included in the tailings fluid flow to flow through
the
screening surface and separate coarse debris larger than or equal to the
predetermined size from the tailings fluid flow, thereby separating the
tailings fluid into
a coarse debris fraction and a screened tailings fluid, a collector body
arranged below
the screening surface of the screening device to receive the screened tailings
fluid; and
a collection bin arranged under or close to the screening device to collect
the coarse
debris removed from the screening surface and/or a tailings fluid loss
resulting from a
tailings running off of the screening surface.
[0034] In another aspect, there is provided pre-treatment screening
assembly
comprising a spillbox feed tank defining a tank cavity and comprising a
tailings inlet for
receiving a tailings fluid flow into the tank cavity; a screening device
comprising a
screening surface receiving the tailings fluid flow spilling from the spillbox
feed tank, the
screening surface being configured to allow material smaller than a
predetermined size
that is included in the tailings fluid flow to flow through the screening
surface and
separate coarse debris larger than or equal to the predetermined size from the
tailings
fluid flow, thereby separating the tailings fluid into a coarse debris
fraction and a
screened tailings fluid; and a collector body defining a collecting cavity and
arranged
below the screening surface of the screening device, the collector body
comprising a
sand discharge opening formed in a bottom portion of the collector body for
collecting
and periodically removing sand accumulated in the collector body.
[0035] In another aspect, there is provided pre-treatment screening
assembly
comprising: a screening device comprising a screening surface receiving a
tailings fluid
flow, the screening surface being configured to allow material smaller than a
predetermined size that is included in the tailings fluid flow to flow through
the
screening surface and separate coarse debris larger than or equal to the
predetermined size from the tailings fluid flow, thereby separating the
tailings fluid into
a coarse debris fraction and a screened tailings fluid; and a collector body
arranged
below the screening surface of the screening device and defining a collecting
cavity to
receive the screened fluid, the collector body comprising: a tailings
discharge outlet for
discharging the screened tailings fluid from the collecting cavity; and a
deflector plate
arranged in the collecting cavity forming a barrier between inflow off the
screening
device and the tailings discharge outlet.
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[0036] In another aspect, there is provided a pre-treatment screening
assembly
comprising: a spillbox feed tank defining a tank cavity and comprising a
tailings inlet for
providing a tailings fluid flow into the tank cavity; a screening device
having a screening
surface receiving the tailings fluid flow from the spillbox feed tank, the
screening
surface being configured to allow material smaller than a predetermined size
that is
included in the tailings fluid flow to flow through the screening surface and
separate
coarse debris larger than or equal to the predetermined size from the tailings
fluid flow,
thereby separating the tailings fluid into a coarse debris fraction and a
screened tailings
fluid; a collector body arranged below the screening surface of the screening
device to
receive the screened tailings fluid; and a frame supporting the spillbox feed
tank, the
screening device and the collector body and configured such that the spillbox
feed
tank, the screening device and the collector body are spaced apart from a
ground
surface on which the frame rests.
[0037] In another aspect, there is provided a pre-treatment screening
assembly
comprising: a plurality of spillbox feed tanks, each spillbox feed tank
defining a tank
cavity and comprising a tailings inlet for providing a tailings fluid flow
into the tank
cavity; at least two screening devices, each screening device defining a
longitudinal
direction and having two opposed longitudinal ends, said at least two
screening
devices extending side to side substantially parallel, and each screening
device having
a screening surface receiving the tailings fluid flow from the spillbox feed
tanks, the
screening surface being configured to allow material smaller than a
predetermined size
that is included in the tailings fluid flow to flow through the screening
surface and
separate coarse debris larger than or equal to the predetermined size from the
tailings
fluid flow, thereby separating the tailings fluid into a coarse debris
fraction and a
screened tailings fluid; an access platform extending along the screening
devices at
one of their longitudinal ends; and a collector body arranged below the
screening
surface of the screening devices to receive the screened tailings fluids.
[0038] In another aspect, there is provided a pre-treatment facility
comprising: a
pre-treatment screening assembly according to the present disclosure; an inlet
line
fluidly connected to the pre-treatment screening assembly to discharge a
tailings fluid
flow onto the screening surface of the screening device; and a discharge line
fluidly
connected to the collector body for downstream treatment operations of the
screened
tailings fluid.
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Date Recue/Date Received 2021-09-07
[0039] In another aspect, there is provided a process for screening
coarse debris
from a tailings fluid flow provided by an inlet line, the process comprising:
providing the
tailings fluid flow to a pre-treatment screening assembly comprising a
spillbox feed
tank, a screening device and a collector body, the spillbox feed tank defining
a tank
cavity and comprising a bottom wall; filling the tank cavity of the spillbox
feed tank with
the tailings fluid flow through a tailings inlet formed in the bottom wall of
the spillbox
feed tank so as to form in the tank cavity a substantially vertical tailings
fluid inlet flow;
discharging a tailings fluid outlet flow from the tank cavity onto the
screening device,
the screening device having a screening surface configured to allow material
smaller
than a predetermined size that is included in the tailings fluid flow to flow
through the
screening surface and separate coarse debris larger than or equal to the
predetermined size from the tailings fluid flow, thereby separating the
tailings fluid into
a coarse debris fraction and a screened tailings fluid; and collecting the
screened
tailings fluid into the collector body.
[0040] In another aspect, there is provided a process for screening
coarse debris
from a tailings fluid flow provided by an inlet line, the process comprising:
providing the
tailings fluid flow to a pre-treatment screening assembly comprising a
spillbox feed, a
screening device and a collector body, the spillbox feed tank defining a tank
cavity;
filling the tank cavity of the spillbox feed tank with the tailings fluid flow
through a
tailings inlet provided above an upper portion of the tank cavity for
discharging
downwardly the tailings fluid flow into the tank cavity; discharging a
tailings fluid outlet
flow from the tank cavity onto the screening device, the screening device
having a
screening surface configured to allow material smaller than a predetermined
size that is
included in the tailings fluid flow to flow through the screening surface and
separate
coarse debris larger than or equal to the predetermined size from the tailings
fluid flow,
thereby separating the tailings fluid into a coarse debris fraction and a
screened tailings
fluid; and collecting the screened tailings fluid into the collector body.
[0041] In another aspect, there is provided a process for screening
coarse debris
from a tailings fluid flow provided by an inlet line, the process comprising:
providing the
tailings fluid flow to a pre-treatment screening assembly comprising a
spillbox feed tank
defining a tank cavity, a screening device and a collector body; filling the
tank cavity of
the spillbox feed tank with the tailings fluid flow through a tailings inlet
formed in the
spillbox feed tank; discharging a tailings fluid outlet flow from the tank
cavity onto the
screening device, the screening device having a screening surface configured
to allow
material smaller than a predetermined size that is included in the tailings
fluid flow to
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Date Recue/Date Received 2021-09-07
flow through the screening surface and separate coarse debris larger than or
equal to
the predetermined size from the tailings fluid flow, thereby separating the
tailings fluid
into a coarse debris fraction and a screened tailings fluid; collecting the
screened
tailings fluid into the collector body; and removing the coarse debris from
the screening
surface.
[0042] In another aspect, there is provided process for screening
coarse debris
from a tailings fluid flow provided by an inlet line and going into a
discharge line, the
process comprising: providing the tailings fluid flow to a pre-treatment
screening
assembly comprising a spillbox feed tank defining a tank cavity, a screening
device and
a collector body having a discharge outlet connected to the discharge line;
filling the
tank cavity of the spillbox feed tank with the tailings fluid flow through a
tailings inlet
formed in the spillbox feed tank; discharging a tailings fluid outlet flow
from the tank
cavity onto the screening device, the screening device having a screening
surface
configured to allow material smaller than a predetermined size that is
included in the
tailings fluid flow to flow through the screening surface and separate coarse
debris
larger than or equal to the predetermined size from the tailings fluid flow,
thereby
separating the tailings fluid into a coarse debris fraction and a screened
tailings fluid;
collecting the screened tailings fluid into the collector body; and deflecting
the screened
tailings fluid inlet flow filling the collector body from the discharge
outlet.
[0043] In another aspect, there is provided a process for screening
coarse debris
from a tailings fluid flow provided by an inlet line and going into a
discharge line, the
process comprising: providing the tailings fluid flow to a pre-treatment
screening
assembly comprising a spillbox feed tank defining a tank cavity, a screening
device and
a collector body having a discharge outlet connected to the discharge line;
filling the
tank cavity of the spillbox feed tank with the tailings fluid flow through a
tailings inlet
formed in the spillbox feed tank; discharging a tailings fluid outlet flow
from the tank
cavity onto the screening device, the screening device having a screening
surface
configured to allow material smaller than a predetermined size that is
included in the
tailings fluid flow to flow through the screening surface and separate coarse
debris
larger than or equal to the predetermined size from the tailings fluid flow,
thereby
separating the tailings fluid into a coarse debris fraction and a screened
tailings fluid;
collecting the screened tailings fluid into the collector body; and removing
sand
accumulated in the collector body.
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Date Recue/Date Received 2021-09-07
[0044] In another aspect, there is provided a process for screening
coarse debris
from a tailings fluid flow coming from an inlet line, the process comprising:
providing the
tailings fluid flow to a pre-treatment screening assembly comprising a
plurality of
spillbox feed tanks with a tank cavity, a screening device, a collector body
and a
plurality of overflow weirs extending outwardly from an upper portion of a
respective
one of the tank cavities; filling each tank cavity of the spillbox feed tanks
with the
tailings fluid flow through a tailings inlet formed in each of the spillbox
feed tanks for the
tailings fluid flow to reach an overflow weir extending from a respective one
of the
spillbox feed tanks; discharging a tailings fluid outlet flow over the
overflow weir of the
tank cavity onto the screening device, the screening device having a screening
surface
configured to allow material smaller than a predetermined size that is
included in the
tailings fluid flow to flow through the screening surface and separate coarse
debris
larger than or equal to the predetermined size from the tailings fluid flow,
thereby
separating the tailings fluid into a coarse debris fraction and a screened
tailings fluid;
collecting the screened tailings fluid into the collector body; and adjusting
the outflow
rate of at least one of the tailings fluid outlet flow for the plurality of
spillbox feed tanks
to have a substantially similar outlet flow rate.
[0045] In another aspect, there is provided a -treatment screening
facility,
comprising: a plurality of pre-treatment screening assemblies according to the
present
disclosure; a plurality of adjustable inlet valves configured to adjust the
tailings inlet
flow in a respective one of the spillbox feed tanks; the adjustable inlet
valves being
adjustable for the respective spillbox feed tanks to provide a substantially
similar outlet
flow into each spillbox feed tank.
[0046] In another aspect, there is provide a pre-treatment screening
facility,
comprising: a pre-treatment screening assembly according to the present
disclosure;
an inlet line fluidly connected to the pre-treatment screening assembly to
discharge a
tailings fluid flow onto the screening surface of the screening device; and a
discharge
line fluidly connected to the collector body for downstream treatment
operations of the
screened tailings fluid.
[0047] The pre-treatment screening assembly according to the present
disclosure
is thus particularly advantageous in that, among other advantages that will be
detailed
in the following description, the screening capacity is improved, the losses
of tailings
fluid are reduced, the screened tailings fluid are efficiently removed from a
collecting
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Date Recue/Date Received 2021-09-07
cavity of the assembly, the coarse debris received and retained by the
assembly are
efficiently removed and the debris are prevented from settling in the
collecting cavity.
BRIEF DESCRIPTION OF THE DRAWINGS
[0048] Figs. 1 and 2 are respectively front and rear perspective
views of a first
implementation of a pre-treatment screening assembly, the pre-treatment
screening
assembly comprising spillbox feed tanks for receiving a tailings fluid flow,
screening
devices receiving the tailings fluid flow from the spillbox feed tanks and
separating the
tailings fluid into a coarse debris fraction and a screened tailings fluid,
and collector
bodies receiving the screened tailings fluid;
[0049] Fig. 3 is a front elevation view of the pre-treatment
screening assembly of
Fig. 1;
[0050] Fig. 4 is a side elevation view of the pre-treatment screening
assembly of
Fig. 1
[0051] Figs. 5 and 6 are respectively front and rear perspective
views of a second
implementation of a pre-treatment screening assembly comprising spillbox feed
tanks,
screening devices and collector bodies;
[0052] Fig. 7 is a cross-section view of a third implementation of a
pre-treatment
screening assembly, the pre-treatment screening assembly further comprising a
debris
collection bin;
[0053] Fig. 8 is an elevation view of an implementation of a spillbox
feed tank;
[0054] Fig. 9 is an elevation view of another implementation of a
spillbox feed
tank;
[0055] Fig. 10 is a side elevation view of an implementation of a
spillbox feed tank
and a screening device;
[0056] Fig. 11 is a cross-section view of an implementation of a
screening device;
[0057] Fig. 12 is a cross-section view of another implementation of a
screening
device, a mechanical cleaning device being mounted to the screening device;
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Date Recue/Date Received 2021-09-07
[0058] Fig. 13 is front perspective view of the screening device of
the pre-
treatment screening assembly of Fig. 1, the screening device having a
screening
surface with an adjustable inclination angle;
[0059] Fig. 14 is a rear perspective view of the screening device of
Fig. 13;
[0060] Fig. 15 is a side elevation view of the screening device of
Fig. 13;
[0061] Fig. 16 is a top plan view of the screening device of Fig. 13;
[0062] Fig. 17 is a cross-section view of a bottom portion of an
implementation of a
collector body comprising a bottom discharge opening;
[0063] Fig. 18 is a rear perspective view of the collector body of
the pre-treatment
screening assembly of Fig. 1;
[0064] Fig. 19 is a top plan view of the collector body of Fig. 18;
[0065] Fig. 20 is a cross-section view of the collector body of Fig.
18;
[0066] Fig. 21 is a rear perspective view of a vortex breaker;
[0067] Fig. 22 is a cross-section view of the vortex breaker of Fig.
21;
[0068] Fig. 23 is a schematic view of an implementation of a pre-
treatment site;
and
[0069] Fig. 24 is a schematic view of another implementation of a pre-
treatment
site.
DETAILED DESCRIPTION
[0070] Systems, processes, devices and techniques are described that
allow pre-
treating oil sands fine tailings in order to remove coarse debris prior to a
chemical
tailings treatment operation, such as chemical enhanced dewatering or other
processes.
[0071] There are provided pre-treatment screening techniques for
removing
coarse debris from oil sands fine tailings and produce screened oil sands fine
tailings,
the screened oil sands fine tailings having improved reactivity and/or
mixability with
chemicals in a subsequent chemical tailings treatment operation. The pre-
treatment
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Date Recue/Date Received 2021-09-07
screening techniques can further produce screened oil sands fine tailings
thereby
enabling to reduce or eliminate damage, clogging and/or plugging of downstream
equipment used in the chemical tailings treatment operation.
General pre-treatment screening assembly
[0072] Pre-treatment screening assemblies can be configured for
receiving debris
containing oil sands fine tailings and for removing coarse debris from an oil
sands fine
tailings fluid. The oil sands fine tailings are for instance retrieved from a
tailings pond.
An oil sands fine tailings fluid that is pumped from the tailings pond by
means of a
dredge or barge typically includes various kinds of debris.
[0073] Figs. 1 to 4 represent a first implementation of the pre-
treatment screening
assembly 100. Figs. 5 and 6 represent a second implementation of the pre-
treatment
screening assembly 100, whereas Fig. 7 represents a third implementation.
Referring
to the first implementation of Figs. 1 to 7, the pre-treatment screening
assembly 100
can include a frame 102, at least one spillbox feed tank 110, at least one
screening
device 140 in fluid communication with the spillbox feed tank 110 and at least
one
collector body 160. In the implementation shown, the spillbox feed tank 110,
the
screening device 140 and the collector body 160 are mounted to the frame 102.
In
other implementations, at least one of the spillbox feed tank 110, the
screening device
140 and the collector body 160 can sit directly on a ground surface.
[0074] As represented for instance in Figs. 6 and 7, the oil sands
tailings fluid is
fed to the pre-treatment screening assembly 100 through an inlet line 104,
which is
connected to the spillbox feed tank 110. The spillbox feed tank 110 then
discharges the
tailings fluid onto the screening device 140. The screening device 140 has a
screening
surface 142 that is configured to separate coarse debris from the tailings
fluid, thereby
producing a screened tailings fluid which flows through the screening surface
142 and
coarse debris that are retained by the screening surface 142. The screened
tailings
fluid is collected by the collector body 160. The screened tailings fluid can
contain
material with a predetermined size enabling the material to flow through the
screening
surface 142 of the screening device 140 toward and into the collector body
160. The
screened tailings fluid collected in the collector body 160 can then be sent
to a
discharge line 108 for downstream chemical tailings treatment operations that
can
include, for instance but without being !imitative, coagulation and/or
flocculation and
dewatering.
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Date Recue/Date Received 2021-09-07
[0075] Some improvements relative to the different components of the
pre-
treatment screening assembly 100 will now be described; the improvements can
either
be considered separately or be combined together.
Spillbox feed tank implementations
[0076] Referring now more particularly to Figs. 8 to 10, the spillbox
feed tank 110,
which is configured to feed the oil sands fine tailings fluid to the screening
device 140,
includes a tailings inlet 112, a tank cavity 114 defined by side walls 116 and
a bottom
wall 118, and an overflow weir 120. The oil sands fine tailings fluid is fed
into the tank
cavity 114 via the tailings inlet 112 and flows upward into the tank cavity
114 until
reaching the overflow weir 120, at which point the tailings fluid flows over
the overflow
weir 120 and down onto the screening device 140.
Tailings inlet
[0077] In the example implementation of the spillbox feed tank 110
from Fig. 9, the
tailings inlet 112 is formed in the bottom wall 118, for example substantially
centrally. In
the existing spillbox feed tank 110' represented for instance in Fig. 8, the
tailings inlet
112' is formed in one of the side walls 116' of the spillbox feed tank 110' so
that, when
a tailings fluid flow is introduced into the tank cavity 114' via the tailings
inlet 112', the
tailings fluid flow rebounds on the side wall opposed to the one in which the
tailings
inlet 112' is formed. This existing spillbox feed tank geometry creates an
uneven flow
distribution across the screening surface of the screening device when the
tailings fluid
flows over the overflow weir onto the screening surface. Such an arrangement
of the
tailings inlet 112' can lead to an overload of one side of the screening
surface, resulting
in high losses of the fine tailings fluid running off of the screening device
on this side.
[0078] On the contrary, in the spillbox feed tank 110 represented in
Fig. 9, in which
the tailings inlet 112 is formed in the bottom wall 118 of the spillbox feed
tank 110, for
instance centrally in the bottom wall 118, the flow bias is significantly
reduced in
comparison with the spillbox feed tank 110 of Fig. 8, resulting in an improved
screening of the tailings fluid. In the spillbox feed tank of Fig. 9, the
tailings fluid defines
a substantially vertical flow in the tank cavity 114 when introduced therein
via the
tailings inlet 112. The tailings fluid can then be discharged uniformly onto
the screening
surface 142 of the screening device 140. As a result, the used surface area of
the
screening surface 142 is increased in comparison with the spillbox feed tank
110' of
Fig. 8, the tailings fluid overflow is reduced and thus the screening capacity
of the pre-
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Date Recue/Date Received 2021-09-07
treatment screening assembly 100 comprising the spillbox feed tank 110 of Fig.
9 is
improved in comparison with a pre-treatment screening assembly comprising the
spillbox feed tank 110' of Fig. 8.
[0079] Referring to Fig. 6, another implementation of the inlet line
104 is disclosed.
In the implementation shown, the pre-treatment screening assembly 100
comprises
four spillbox feed tanks 110 arranged by pairs and spilling the oil sands
tailings fluid on
two screening devices 140. Unlike the spillbox feed tanks 110 represented in
Figs. 8
and 9 in which the oil sands tailings fluid forms a vertically rising fluid
flow in the tank
cavity 114, in the implementation represented in Fig. 6, the tailings inlet
112 comprises
a substantially horizontally extending distribution pipe 117. The distribution
pipe 117
extends above one of the pairs of spillbox feed tanks 110 and comprises, in
the
implementation shown, two opposed longitudinal outlets 115 for the oil sands
tailings
fluid to be discharged downwardly into each one of pair of spillbox feed tank
110. In
other words, the tailings inlet 112 is provided above an upper portion of the
tank cavity
114. The inlet distribution pipe 117 extends substantially horizontally above
the upper
portion of the tank cavity 114.This substantially horizontal arrangement of
the tailings
inlet 112 limits the risk that coarse debris settle and plug the tailings
inlet 112 of the
spillbox feed tank 110. In the implementation shown, the pre-treatment
screening
assembly 100 further comprises two spaced apart vertically extending
distribution pipes
105 fluidly connecting the inlet line 104 and the tailings inlet 112.
Dimensions of the overflow weir being narrower than dimensions of the
screening surface
[0080] As represented for instance in Fig. 7, the screening device
140 has an
upstream inlet 144, the tailings fluid flow being discharged onto the
screening surface
142 of the screening device 140 over the overflow weir 120 of the spillbox
feed tank
110 at the upstream inlet 144.
[0081] As represented for instance in Fig. 10, the screening device
140 has a
plurality of substantially parallel screening bars that are spaced apart from
each other
so as to define openings on either side of each screening bar. The screening
device
140 also includes a plurality of supporting bars forming boundaries of the
screening
surface 142. The supporting bars are arranged so that the screening surface
142 of the
screening device 140 is substantially rectangular and defines a length L1 and
a width
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Date Recue/Date Received 2021-09-07
L2, whereas the overflow weir 120 of the spillbox feed tank 110 defines a
width W, as it
is represented for instance in Fig. 10.
[0082] In some existing implementations of the pre-treatment
screening assembly,
the width of the overflow weir substantially corresponds to the width of the
screening
surface, so that a significant quantity of the tailings fluid that is
discharged from the
spillbox feed tank on the screening device is in fact discharged on the
supporting bars
of the screening device, and thus is discharged outside the screening surface,
i.e.
outside the collector body 160. This results in significant amounts of the
tailings fluid
that are not screened by the pre-treatment screening assembly.
[0083] In the shown implementation, as represented for instance in
Fig. 10, the
overflow weir 120 is dimensioned so that its width W is narrower than the
width L2 of
the screening surface 142. To this end, baffle plates 124 can be arranged in
the tank
cavity 114 of the spillbox feed tank 110, substantially parallel to the side
walls 116, so
as to the reduce the width W of the overflow weir 120 over which the tailings
fluid is
discharged at the upstream inlet 144 of the screening device 140 and to direct
the
tailings fluid flow towards the overflow weir 120. In the shown
implementation, two
baffle plates extend in the tank cavity, but it could also be conceived one
single baffle
plate extending in the tank cavity to direct the tailings fluid flow towards
the overflow
weir 120.
[0084] In some implementations, the width W of the overflow weir 120
represents
less than about 90% of the width L2 of the screening surface 142. In some
other
implementations, the width W of the overflow weir 120 represents less than
about 85%
of the width L2 of the screening surface 142. In yet other implementations,
the width W
of the overflow weir 120 represents less than about 80% of the width L2 of the
screening surface 142.
[0085] As the width W of the overflow weir 120 is reduced relative to
the width L2
of the screening surface 142, the losses of the tailings fluid (i.e. the
amount of the
tailings fluid being discharged outside the screening surface 142 of the
screening
device 140, and thus outside the collector body 160) are reduced, and thus the
capacity of the pre-treatment screening assembly 100 is increased compared to
the
pre-treatment screening assemblies in which the width of the overflow weir
substantially corresponds to the width of the screening surface.
Control and regulation devices
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Date Recue/Date Received 2021-09-07
[0086] As detailed above, the tailings fluid is fed into the tank
cavity 114 of the
spillbox feed tank 110 via the tailings inlet 112 and then flows over the
overflow weir
120 and down to the screening device 140 from the upstream inlet 144 (which
corresponds to an upper edge of the overflow weir 120). Referring to Fig. 7,
the pre-
treatment screening assembly 100 can further comprise at least one adjustable
valve
113 (or adjustable inlet valve) configured to adjust the tailings fluid inlet
flow in the
spillbox feed tank 110, for instance by cooperating with the tailings inlet
112. The
spillbox feed tank 110 can further comprise a level sensor 126, as represented
in Fig.
7, the level sensor 126 being configured to measure the tailings fluid level
in the tank
cavity 114 of the spillbox feed tank 110. In the implementation represented in
Fig. 7,
the adjustable inlet valve 113 is arranged in the vicinity of ¨ proximate -
the tailings inlet
112, but the adjustable valve 113 could be arranged elsewhere. For instance,
the
adjustable valve 113 could be arranged directly on the inlet line 104. In the
implementation represented in Fig. 6, the adjustable valve could further be
arranged,
for instance and without being !imitative, on the distribution pipe 117, or on
the outlet
115. The pre-treatment screening assembly 100 could further comprise an
adjustable
valve (which can also be referred to as an adjustable outlet valve) mounted
down the
collector body 160 and cooperating with a discharge pump configured to make
the
screened tailings fluid circulate in the discharge line 108.
[0087] For instance and without being !imitative, the level sensor
126 comprises
two distinct pressure transmitters that are arranged in the tank cavity 114
and that
measure the pressure of the tailings fluid at two distinct locations of the
tank cavity 114.
In another implementation, as represented in Fig. 1, the level sensor 126 can
be
arranged down a collecting cavity 166, for instance in a lower portion of the
collector
body 160. On the basis of a pressure difference between pressures measured by
the
two distinct pressure transmitters, the level sensor 126 determines the level
of the
tailings fluid in the tank cavity 114. For instance, the level sensor 126 can
use the
following principle: P=d*g*h, where P is the pressure difference between two
vertical
positions of a fluid, d is the density of the fluid, g is the gravitational
constant and h is
the distance between the two vertical positions at which the pressures of the
fluid are
measured, to determine the level of the tailings fluid in the tank cavity 114.
Other
implementations can be conceived to determine the level of the tailings fluid
in the tank
cavity 114. The adjustable valve 113 can then be actuated in response to the
tailings
fluid level determined by the level sensor 126.
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Date Recue/Date Received 2021-09-07
[0088] For instance, when the level determined by the level sensor
126 is above a
first pre-determined threshold, the adjustable valve 113 can be actuated to
cooperate
with the tailings inlet 112 so as to reduce the tailings fluid flow rate at
the tailings inlet
112. To this end, the adjustable valve 113 can be designed to cooperate with a
pump ¨
or inlet pump - mounted in the inlet line 104 to feed the spillbox feed tank
110 with the
tailings fluid.
[0089] On the other hand, when the tailings fluid level determined by
the level
sensor 126 is below a second pre-determined threshold, the adjustable valve
113
cooperating with the tailings inlet 112 can be actuated so as to increase the
tailings
fluid flow rate at the tailings inlet 112.
[0090] On the basis of the level measurements by the level sensor 126
(arranged
for instance and without being !imitative in the tank cavity 114 or in the
collecting cavity
166), the adjustable valve 113 can also cooperate with transfer pumps (e.g.,
either inlet
transfer pumps or outlet transfer pumps, depending on the location of the
transfer
pumps with regards to the inlet line 104 and the discharge line 108) of the
pre-
treatment screening assembly 100. For instance, when the tailings fluid level
in the
tank cavity and/or in the inlet line 104 and/or in the collecting cavity 166
is below a pre-
determined threshold, the adjustable valve 113 can cooperate with the transfer
pump
configured to feed the spillbox feed tank 110 with the tailings fluid, for the
transfer
pump to speed up and/or for the adjustable valve 113 to open up, so as to
increase the
flow of the tailings fluid in the spillbox feed tank 110. Alternatively, when
the tailings
fluid level in the tank cavity 114 and/or in the inlet line 104 and/or in the
collecting
cavity 166 is above a pre-determined threshold, the adjustable valve 113 can
cooperate with the transfer pump configured to feed the spillbox feed tank 110
with the
tailings fluid, for the transfer pump to slow down and/or for the adjustable
valve 113 to
close up, so as to decrease the flow of the tailings fluid in the spillbox
feed tank 110.
The transfer pumps can be operated for instance to feed the spillbox feed tank
110 with
the tailings fluid, to discharge the tailings fluid on the screening surface
142 of the
screening device 140 or to make the screened tailings fluid circulate in the
discharge
line 108. It is understood that the level sensor 126 could also be configured
to
cooperate directly with any of the inlet and/or outlet transfer pumps, without
cooperating with any adjustable valve 113. For instance, when the tailings
fluid level in
the tank cavity and/or in the inlet line 104 and/or in the collecting cavity
166 is below a
pre-determined threshold, the level sensor 126 can cooperate with the outlet
transfer
pump configured to feed the discharge line 108 with the screened tailings
fluid, for the
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Date Recue/Date Received 2021-09-07
outlet transfer pump to slow down, so as to decrease the flow of the screened
tailings
fluid in the discharge line 108. Alternatively, when the tailings fluid level
in the tank
cavity 114 and/or in the inlet line 104 and/or in the collecting cavity 166 is
above a pre-
determined threshold, the level sensor 126 can cooperate with the outlet
transfer pump
configured to feed the discharge line 108 with the screened tailings fluid,
for the outlet
transfer pump to speed up, so as to increase the flow of the screened tailings
fluid in
the discharge line 108. The level sensor 126 could also be configured to
cooperate with
an outlet adjustable valve to adjust the flow of the screened tailings fluid
in the
discharge line 108.
[0091] It is to be noted that, in some implementations, the frame 102
provides the
pre-treatment screening assembly 100 with an elevated structure with regards
to a
ground surface supporting the screening assembly 100. In other words, the
frame 102
is designed to space the spillbox feed tank 110, the screening device 140 and
the
collector body 160 from the ground surface. The frame 102 is thus configured
to
provide the different pumps of the assembly 100 with adequate suction
pressure, in
particular to ensure an efficient removal of the screened tailings fluid from
the collector
body 160.
Screening device implementations
[0092] Referring again to Fig. 7, the tailings fluid is discharged
from the spillbox
feed tank 110 over the overflow weir 120 into the screening device 140 at the
upstream
inlet 144. The screening device 140 further comprises a bottom end 146, as
represented for instance in Fig. 2. The bottom end 146 is designed to ease the
removal
of the coarse debris received and retained by the screening surface 142
towards a
collection area 180. To enhance the removal of the coarse debris towards the
collection area 180, the screening surface 142 can be inclined downwardly so
as to
define a first inclination angle al with respect to a horizontal direction;
the first
inclination angle al can range between about 25 degrees and about 45 degrees.
For
instance, the first inclination angle al measures about 30 degrees.
Adjustable inclination of the screening surface
[0093] It should be noted that the first inclination angle al can be
adjustable so as
to adapt to the nature of the tailings to be screened or perform specific
operational
steps such as maintenance operations for instance. For instance, the screening
device
140 is configured to have an operating mode as well as a cleaning mode in
which the
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Date Recue/Date Received 2021-09-07
inclination angle al is adjustable. In the shown implementation, as
represented for
instance in Figs. 13 to 16, the pre-treatment screening assembly 100 further
comprises
a winch 148 that is configured to adjust the first inclination angle al formed
by the
screening surface 142 relative to the horizontal direction when the screening
device
140 is configured in the cleaning mode. In the implementation shown, the winch
148 is
configured to be manually actuated, but a pre-treatment screening assembly 100
having a motorized system configured to adjust the first inclination angle al
of the
screening surface 142 could also be provided. The pre-treatment screening
assembly
100 could also comprise a plurality of interchangeable screening surfaces 142
each
forming a different first inclination angle al with respect to a horizontal
direction. As a
result, it is possible to adapt the arrangement of the screening surface 142
of the
screening device 140 so as to alternatively enable self-cleaning of the
screening
surface 142 or at least ease the discharging of the coarse debris from the
screening
surface 142 towards the collection area 180, or to reduce the tailings fluid
losses
resulting from a running off of the screening surface 142.
[0094] In other words, it is understood that the screening device 140
is designed to
allow a user to reduce the first inclination angle al of the screening surface
142, if the
coarse debris loading on the screening surface 142 is insufficient and/or if
the tailings
fluid losses are excessive. A user can also increase the first inclination
angle al of the
screening surface 142 so as to increase the self-cleaning of the screening
surface 142,
for instance under heavy debris loading or when it is considered that the
amount of the
coarse debris on the screening surface 142 has reached a pre-determined
threshold.
[0095] The pre-treatment screening assembly can further comprise a
sensor
designed to evaluate the quantity of coarse debris on the screening surface.
The pre-
treatment screening assembly could further comprise a control circuit
receiving a signal
from the sensor when the quantity of coarse debris on the screening surface
measured
by the sensor has reached a pre-determined threshold, the control circuit then
actuating the winch 148 as seen on Fig. 13 to 17 ¨ or any other adapted
mechanical
device - so as to increase the value of the first inclination angle al formed
between the
screening surface and the horizontal direction.
[0096] The pre-treatment screening assembly could further comprise an
additional
sensor designed to evaluate the quantity of tailings fluid losses resulting
from a running
off of the screening surface; the control circuit could further be designed to
receive a
signal from the additional sensor when the quantity of tailings fluid losses
has reached
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a pre-determined threshold, the control circuit then actuating the winch 148
as seen on
Fig. 13 to 17 ¨ or any other adapted mechanical device - so as to reduce the
first
inclination angle al formed between the screening surface and the horizontal
direction.
[0097] In another implementation of the screening device 140
represented for
instance in Fig. 11, the screening surface 142 could have a concave profile,
thereby
having a varying slope decreasing from a top end 147 of the screening device
140 to
the bottom end 146 of the screening device 140. For instance, the angle formed
between the screening surface 142 and the horizontal direction can vary
between
about 0 degree, at the bottom end 146 of the screening device 140, and about
80
degrees, at the top end 147 of the screening device 140.
[0098] The use of a concave profile for the screening surface 142 is
particularly
efficient for the automatic removal and/or accumulation of the coarse debris
reaching
the screening surface 142, without resulting from an increase of the tailings
fluid losses
resulting from a running off of the screening surface 142.
Mechanical cleaning device
[0099] In some implementations, as represented in Fig. 12, the pre-
treatment
screening assembly 100 further comprises a mechanical cleaning device 170 that
is
configured to mechanically remove the coarse debris from the screening surface
142 of
the screening device 140. The mechanical cleaning device 170 can regularly
remove
the coarse debris from the screening surface 142 and/or when the quantity of
the
coarse debris on the screening surface 142 has reached a pre-determined
threshold.
To this end, the mechanical cleaning device 170 can cooperate with the above-
mentioned control circuit and be actuated in response to a signal sent by the
above-
mentioned sensor that is designed to evaluate the quantity of the coarse
debris on the
screening surface 142.
[00100] For instance and without being !imitative, the mechanical
cleaning device
170 comprises rakes and/or rotating brushes designed to go all over the
screening
surface 142 so as to pull the coarse debris away from the screening surface
142; for
instance, the mechanical cleaning device 170 pulls the coarse debris toward
the
collection area 180.
[00101] In some implementations, as represented in Fig. 12, the
screening device
140 comprises an upper portion 150 having an upper screening surface 151, and
a
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Date Recue/Date Received 2021-09-07
lower portion 152 having a lower screening surface 153. The upper screening
surface
151 defines an upper angle a2 with the horizontal direction and the lower
screening
surface 153 defines a lower angle a3 relative to the horizontal, the upper
angle a2
being greater than the lower angle a3. In some implementations, the upper
angle a2
can be between about 30 degrees and about 60 degrees, and the lower angle a3
can
be between about 15 degrees and about 30 degrees. Optionally, the upper angle
a2
can be between about 40 degrees and about 50 degrees, and the lower angle a3
can
be between about 20 degrees and about 25 degrees. In some implementations, the
upper angle a2 can be at least about 1.5 times greater than the lower angle
a3.
Optionally, the upper angle a2 can be about two times greater than the lower
angle a3.
[00102] The arrangement of the upper and lower portions 150, 152 of
the screening
device 140 enables to efficiently separate the liquids from the coarse debris
of the
tailings fluid, and to direct the coarse debris towards the lower portion 152,
so as to
ease their removal from the screening device 140.
[00103] As represented in Fig. 12, the mechanical cleaning device 170
can be
arranged on the lower portion 152 of the screening device 140, so that the
dimensions
of the mechanical cleaning device 170 are reduced with regards to a screening
device
140 having one single inclination angle relative to the horizontal direction,
in which
case the mechanical cleaning device 170 would be dimensioned to go all over
the
screening surface 142.
[00104] As represented for instance in Fig. 12, the mechanical
cleaning device 170
can comprise at least one rake 171 to remove coarse debris from the lower
screening
surface 153 of the lower portion 150. The rake 171 can be mounted on a
caterpillar 191
to automatically remove coarse debris from the screening surface 142 of the
screening
device 140.
[00105] The mechanical cleaning device 170 can further comprise a
shaker (not
illustrated in Fig. 12) designed to make the screening surface 142 vibrate so
as to more
easily accumulate the coarse debris, and then to more easily remove them.
Debris collection bin
[00106] In some existing implementations of the pre-treatment
screening assembly,
the coarse debris that are removed from the screening device are rejected in
the
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Date Recue/Date Received 2021-09-07
tailings pond. However, such a coarse debris management requires in particular
from
the screening device to be close to the tailings pond.
[00107] As it is represented for instance in Fig. 7, the pre-treatment
screening
assembly 100 can further comprise a debris collection bin 172 that is placed,
for
instance and without being !imitative, under, beside or in the vicinity of the
screening
device 140, so as to collect the coarse debris that are removed from the
screening
surface 142, for instance by the above described mechanical cleaning device
170. The
debris collection bin 172 can also be configured to collect at least partially
a tailings
fluid loss resulting from a tailings running off of the screening surface. The
coarse
debris that are collected in the debris collection bin 172 can then be hauled
away at an
appropriate dump location, so as to permanently be removed from the tailings
pond
202 and to reduce their long-term impact on the tailings fluid dredging. The
dimensions
of the debris collection bin 172 are adapted so that the debris collection bin
172 will
only need to be emptied, for instance, a few times a month.
[00108] Still referring to Figure 7, the pre-treatment screening
assembly 100 can
also comprise a debris heater 173 designed to heat the debris collection bin
172 so
that its content will not freeze, which would make it more complex for the
coarse debris
to be removed from the debris collection bin 173. As mentioned above, the
debris
collection bin 172 can also be configured to at least partially collect
tailings fluid
overflow resulting from tailings running off of the screening surface. The pre-
treatment
screening assembly 100 can further comprise a debris collection pump mounted
to an
end of a pipe 174 extending partially in the debris collection bin 173, as
represented in
Fig. 7, that is designed to pump the tailings fluid loss from the debris
collection bin 172
and to inject them back into the spillbox feed tank 110. The debris collection
bin 172
and the debris collection pump 174 enable to increase the quantity of the
tailings fluid
that is processed by the pre-treatment screening assembly 100. Moreover, the
use of
the debris collection bin 172 enables to reduce constraints relative to the
location of the
screening device 140 close to the tailings pond 202, for debris removal
purposes.
Collector body implementations
[00109] As mentioned above, after the oil sands fine tailings fluid
has been
discharged at the upstream inlet 144 of the screening device 140, the screened
oil
sands fine tailings fluid is collected by the collector body 160.
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[00110] The collector body 160 can be sized and configured to enable
the flow of
the screened tailings fluid to accumulate and form a more uniform composition
of the
screened tailings. Thus, for instance, fluctuations in the composition of the
tailings
retrieved from the tailings pond 202 can be attenuated both by the removal of
the
coarse debris via the screening device 140 and also by the accumulation of the
screened tailings fluid having greater uniformity than the tailings fluid
piped from the
tailings pond.
[00111] In the shown implementation, the collector body 160 has side
walls 162 and
a bottom wall 164 that define together a collecting cavity 166.
[00112] In the implementation shown in Figs. 1 to 4 and Fig. 19, the
pre-treatment
screening assembly 100 further comprises two overflow weirs 60 located at
opposed
longitudinal ends of the collector body 160. The overflow weirs 60 are
designed to
collect screened tailings fluid overflowing from the collector body 160. The
overflow
weirs 60 comprise an overflow outlet 62, for the tailings fluid to be removed
from the
overflow weirs 60.
Design of the collector body
[00113] As represented for instance in Figs. 2 and 17, the bottom wall
164 of the
collector body 160 can comprise a bottom discharge opening 165 - or sand
discharge
opening - designed to easily remove debris, such as sand particles, that build
up or
accumulate in the collector body 164 and that have not been removed by the
screening
device 140. In the implementation shown, the discharge opening 165 is formed
in a
side wall 162 of the collector body 160 opposed to the side wall 162 in which
the
discharge outlet 167 is formed. In some implementations, debris is removed
from the
collector body 160 via the bottom discharge opening 165 using, for instance, a
pump
fluidly connected to the collecting cavity 166 of the collector body 160.
[00114] In some other implementations, as represented in Figs. 1 to 4,
the pre-
treatment screening assembly 100 further comprises a flushing inlet nozzle 50,
for
instance formed in a side wall 62 opposed to the one in which the bottom
discharge
opening 165 is formed. Flush water can thus circulate in the collecting cavity
166, in a
bottom portion thereof, from the flushing inlet nozzle 50 towards the bottom
discharge
opening 165, so as to push debris towards the bottom discharge opening 165 and
remove the debris from the collector body 160 via the bottom discharge opening
165,
thus preventing the debris from settling in the bottom portion of the
collecting cavity
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Date Recue/Date Received 2021-09-07
166. The bottom discharge opening 165 thus forms a flushing outlet of the
collector
body 160. It is appreciated that the shape, the configuration and the location
of the
bottom discharge openings 165, as well as the shape, the configuration and the
location of the flushing inlet nozzles 50 can vary from the implementation
shown. The
pressure of the flushing water can also be adapted to the dimensions of the
collector
body 160, and to the debris having to be removed therefrom.
[00115] The collector body 160 can be designed to direct the debris
towards the
bottom discharge opening 165, in order to ease their removal outside the
collector body
160. The collector body 160 can therefor have a bottom conical shape or, as
represented for instance in Fig. 20, at least one sloped side wall 163
extending from
one of the side walls 162 and being designed to direct debris towards the
bottom
discharge opening 165. For instance, the sloped side wall 163 starts midway up
the
side wall 162 of the collector body 160 opposite the side wall 162 in which
the
discharge outlet 167 is formed, and slopes downwardly towards the discharge
outlet
167. As represented in Fig. 20, the sloped side wall 163 can extend between
one of the
side walls 162 and the bottom wall 164.
Air reduction in the screened tailings
[00116] Referring to Fig. 2, the screened tailings fluid collected in
the collecting
cavity 166 of the collector body 160 is then released from the collector body
166
through at least one discharge outlet 167 that can be located in the bottom
wall 164 or
in a bottom portion of one of the side walls 162 of the collector body 160 and
connected to the discharge line 108. The discharge line 108 then sends the
screened
tailings fluid to further treatments, such as flocculation and dewatering of
the screened
tailings. The pre-treatment screening assembly 100 comprises at least one
discharge
pump 109 to make the screened tailings fluid circulate in the discharge line
108.
[00117] In some pre-treatment screening assemblies, air can be trapped
within the
screened tailings fluid flow, when the screened tailings fluid falls through
the screening
device. The formed air pockets sometimes disrupt operation of the pre-
treatment
screening assembly, for instance by disrupting the working of the discharge
pump.
[00118] So as to reduce the negative impact of the air mixing on the
pre-treatment
of the tailings, as represented in Figs. 1, 2 and 7, the discharge outlet 167
can be
arranged in one of the side walls 162 of the collector body 160 that extends
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Date Recue/Date Received 2021-09-07
perpendicularly to the upstream inlet 144 of the screening device 140 and
perpendicularly to the width L2 of the screening surface 142.
[00119] The upstream inlet 144 of the screening device 140 and the
discharge
outlet 167 of the collector body 160 can be arranged on a same side of the
collector
body 160 (i.e., so as to be spaced apart from each other, the upstream inlet
144 being
directly vertically above the tailings discharge outlet 167). In other words,
the tailings
fluid is discharged at the upstream inlet 144 in a first direction and the
screened tailings
fluid is discharged at the tailings discharge outlet 167 in a second direction
opposed to
the first direction. As the tailings fluid passes through the screening
surface 142, the
tailings fluid can plummet substantially vertically into the collector body
160 directly
above the discharge outlet 167. As that plummeting fluid hits the tailings
fluid level in
the collector body 160, the tailings fluid can entrain air into the collector
body liquid
phase (like a waterfall), which can then increase the risk of short circuiting
to the
discharge outlet 167 directly below and on same side. The pre-treatment
screening
assembly 100 can thus further comprise at least one deflector plate 168
arranged in
the collecting cavity 166 of the collector body 160, for instance above the
discharge
outlet 167, as represented for instance in Figs. 19 and 20. The deflector
plate 168
provides a barrier between inflow off the screening device 140 and the
discharge outlet
167 of the collector body 160 to limit the risk of tailings fluid inflow short
circuiting to the
discharge outlet 167 and carrying air with it. In other words, the deflector
plate 168
creates a path of travel for the tailings fluid in the collector body 160 that
increases
retention time for a particle of fluid allowing more time for air to rise to
surface and
dissipate instead of being pulled into the discharge outlet 167 and entrained
in the
discharge line 108.
[00120] In the implementation represented, the deflector plate 168 is
oriented at an
inclination angle a4 with respect to the horizontal direction. In an
implementation, the
inclination angle a4 is between about 15 degrees and about 75 degrees.
Optionally, the
inclination angle a4 is between about 30 degrees and about 60 degrees. Further
optionally, the inclination angle a4 is between about 40 degrees and about 50
degrees.
[00121] In some other implementations, as represented for instance in
Figs. 20, the
sloped deflector plate 168 extends only partially between two opposed side
walls 162
of the collector body 160, a substantially horizontal portion 169 extending
between the
deflector plate 168 and the side wall 162 opposed to the one from which the
deflector
plate 168 extends.
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Date Recue/Date Received 2021-09-07
[00122] As represented in Figs. 20 to 22, the pre-treatment screening
assembly 100
can further comprise a vortex breaker 161 mounted into the discharge outlet
167 of the
collector body 160 and extending at least partially in the collecting cavity
166.
[00123] As represented for instance in Figs. 21 and 22, the vortex
breaker 161
comprises a substantially cylindrical body 190 and a vortex breaking core 192
arranged
in the cylindrical body 190. In the shown implementation, the vortex breaking
core 192
has a crossed-shaped section: the vortex breaking core 192 comprises two
plates 194,
195 assembled together in a substantially perpendicular way, the two plates
194, 195
being secured to the cylindrical body 190.
Pre-treatment screening assembly implementations
[00124] It should be understood that the present description is not
limited to a pre-
treatment screening assembly 100 comprising solely one spillbox feed tank 110,
one
screening device 140 and one collector body 160, the different elements being
mounted to the frame 102.
[00125] Indeed the pre-treatment screening assembly 100 can include a
plurality of
screening devices mounted adjacently and operating in parallel with respect to
each
other.
[00126] As represented for instance in Figs. 1 to 4, the pre-treatment
screening
assembly 100 can include four spillbox feed tanks 110, each spillbox feed tank
110
having an overflow weir 120 for discharging a tailings fluid flow on a
corresponding
screening device 140.
[00127] The pre-treatment screening assembly 100 can have one single
collector
body 160 arranged below the different screening devices 140, or there can be
one or
more collector bodies 160 for each overlying screening device 140.
[00128] In the implementation of the pre-treatment screening assembly
100
comprising a plurality of collector bodies 160, each collector body can have a
discharge
outlet 167, or the pre-treatment screening assembly 100 can have a possibly
larger
single discharge outlet 167. It is thus possible to form the single discharge
outlet 167 in
one of the side walls 162 or bottom walls 164 of the collector bodies 160 so
as to adapt
the pre-treatment screening assembly 100 to the location where it is
installed.
Optimization of the pre-treatment screening assembly design
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Date Recue/Date Received 2021-09-07
[00129] As represented in Figs. 1 to 6, in order to improve the
operation of the pre-
treatment screening assembly 100, the assembly 100 can include platforms,
stairways
and railings 106 which allow an operator to easily and safely monitor the pre-
treatment
screening assembly 100, for example to monitor the screening surfaces 142.
[00130] In some implementations, as represented in Figs. 1 and 2,
platforms 106
are arranged between two adjacent screening devices 140. As represented in
Figs. 5
and 6, the pre-treatment screening assembly 100 can comprise one platform 106
extending along a longitudinal direction L of the pre-treatment screening
assembly 100,
and substantially perpendicularly to the length L1 of the screening devices
140.
[00131] This arrangement of the platform 106 enables to increase the
dimensions
of the screening surfaces 142 of the two adjacent screening devices 140
compared to
an implementation wherein the pre-treatment screening assembly 100 includes
platforms 106 which are arranged between two adjacent screening devices 140.
Other
arrangements of the platform 106 can be conceived within the framework of the
present disclosure; for instance, the platform 106 can be arranged so as to
overhang
the screening devices 140.
[00132] As represented in Fig. 5, the pre-treatment screening assembly
100 can
further comprise vertically extending paths 107, such as ladders, extending
from the
ground towards the platforms 106 surrounding or extending between or along the
screening devices 140, for a user to easily and safely access the screening
devices
140, when the frame 102 comprises an elevated structure. In the shown
implementation, the paths 107 are mounted to the frame 102. The pre-treatment
screening assembly 100 can further comprise intermediate platforms 103 for
instance
extending along the lower portion of the collector body 160, for a user to
easily access,
for instance and without being !imitative, the discharge outlets 167 or the
bottom
discharge openings 165.
[00133] As represented in Figs. 1, 13 and 14, the screening devices
140 can
comprise each an access door 157, for instance to let a user easily access the
screening surface 142, to clean and/or repair it, whenever needed.
In the implementation of the pre-treatment screening assembly 100 in which the
platforms 106 are arranged between two adjacent screening devices 140, as
represented in Figs. 1 and 2, the access doors 157 of the two adjacent
screening
devices usually face each other, on each side of the corresponding platform
106.
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Date Recue/Date Received 2021-09-07
[00134] In the implementation of the pre-treatment screening assembly
100
comprising one single platform 106, as represented in Fig. 5, the access doors
of the
screening devices 140 can be arranged at a longitudinal end of the screening
device
140 at which the sole platform 106 extends.
[00135] In the implementation of the pre-treatment screening assembly
100 in
which the platforms 106 do not extend between two adjacent screening devices
140,
the dimensions of the screening surfaces 142 of the screening devices 140 can
be
increased. The overall screening surface of the pre-treatment screening
assembly 100
can thus be increased, and so is the pre-treatment capacity of the pre-
treatment
screening assembly 100.
[00136] As represented in Fig. 1, the pre-treatment screening assembly
100 can
further have a manway 70 for instance formed in one of the side walls 162 of
the
collector body 160, to allow a user, for instance for maintenance and/or
repair
purposes, to access the collecting cavity 166.
Plurality of adjustable overflow weirs
[00137] In the shown implementation from Figs. 1 and 2, the pre-
treatment
screening assembly 100 comprises a plurality of spillbox feed tanks 110, each
of them
having an overflow weir 120.
[00138] In some implementations, the overflow weirs 120 of the
spillbox feed tanks
110 are adjustable and configured to ensure that the different spillbox feed
tanks 110 of
the pre-treatment screening assembly 100 have a substantially similar outlet
flow that
is discharged on the corresponding screening device 140. Indeed, the ground on
which
the pre-treatment screening assembly 100 is installed via the frame 102 can be
uneven, either at the installation of the screening assembly 100, or over
time. The
inclination of the pre-treatment screening assembly 100 can result in pressure
differentials between the tailings inlets 112 of different spillbox feed tanks
110 and
between the discharge outlets 167 of the collector bodies 160. As a result,
one of the
screening devices 140 can lack tailings fluid, whereas another one of the
screening
devices 140 can be overflowed. To limit the tailings fluid flow differences
between the
different screening devices 140, the above-described adjustable valves 113 can
be
adjusted differently between the different screening devices 140, and/or the
adjustable
overflow weirs 120 can be adjusted according to an elevation of each spillbox
feed tank
110 relative to the ground on which the frame 102 is located. In other words,
the
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Date Recue/Date Received 2021-09-07
adjustable overflow weirs 120 enable to compensate for differences in the
elevation of
the different spillbox feed tanks 110 and to effectively re-establish a
substantially
similar level across all spillbox feed tanks 110.
[00139] The adjustability of the overflow weirs 120 can be implemented
in different
manners. For instance, the spillbox feed tanks 110 can have a mounting base
130, the
spillbox feed tanks 110 being mounted to the frame 102 of the pre-treatment
screening
assembly 100 via their respective mounting base 130. The mounting base 130 can
be
adjustable so as to adjust the elevation of the overflow weir 120.
[00140] Alternatively, the overflow weirs 120 of the spillbox feed
tanks 110 can
comprise adjustable plates that are configured to modify the elevation at
which the
tailings fluid flow will flow out of the tank cavity 114 of the spillbox feed
tank 110.
[00141] It is thus understood that the adjustable overflow weirs 120
of the spillbox
feed tanks 110 allows to more evenly discharge the tailings fluid flow on the
screening
surface 142 of the different screening devices 140, thus improving the
capacity and
efficiency of the pre-treatment screening assembly 100.
Pre-treatment site implementations
[00142] In another aspect, there is provided a pre-treatment site for
the pre-
treatment of fine tailings, comprising several pre-treatment screening
assemblies
arranged close to a tailings pond.
[00143] As represented in Fig. 23, an existing pre-treatment site 200'
can include
six pre-treatment screening assemblies 100', each of them having, for
instance, four
screening devices 140'. The four screening devices 140' of each pre-treatment
screening assembly 100' are substantially parallel to each other so that each
pre-
treatment screening assembly 100' has a substantially rectangular shape with a
long
side 11' and a small side 12', the small side 12' of the assembly 100'
corresponding
substantially to a length of the screening devices 140.
[00144] Moreover, the six pre-treatment screening assemblies 100' of
the pre-
treatment site 200' represented in Fig. 23 are arranged side by side along
their long
side 11', so that the twenty-four screening devices 140 are arranged in a
substantially
parallel manner along the tailings pond 202.
Optimized footprint pre-treatment site
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Date Recue/Date Received 2021-09-07
[00145] The pre-treatment site 200 represented in Fig. 24 comprises,
for instance,
three pre-treatment screening assemblies 100, each of them having for instance
four
screening devices 140. Each pre-treatment screening assembly 100 has a
substantially
rectangular shape with a long side 11 and a short side 12, the four corners of
the
rectangular being constituted by the four screening devices 140.
[00146] The three pre-treatment screening assemblies 100 are arranged
side by
side, their long sides Ii being substantially parallel to each other.
[00147] The footprint of the pre-treatment site 200 represented in
Fig. 24 is thus
significantly reduced compared to the footprint of the existing pre-treatment
site 200' as
represented in Fig. 23. Furthermore, thanks to an increase of the efficiency
of the pre-
treatment screening assemblies 100, the efficiency of the disclosed pre-
treatment site
200 of Fig. 24 is substantially identical or greater than the efficiency of
the existing pre-
treatment site 200' of Fig. 23.
[00148] Moreover, among many significant advantages, the reduced
footprint of the
pre-treatment site 200 compared to the pre-treatment site 200' of Fig. 23
enables to
reduce the dimensions of the inlet line 104 of the different pre-treatment
screening
assemblies 100. Less collection areas 180 and/or less debris collection bins
172 for the
collecting of the coarse debris are also required. It is appreciated that the
location and
the number of the pre-treatment screening assemblies 100 and/or the screening
devices 140 of the pre-treatment site 200 can vary from the implementation
shown.
Method implementations
[00149] In another aspect, there is provided a method for screening
debris from an
oil sands fine tailings fluid to pre-treat the oil sands fine tailings fluid
for chemical
treatment, such as flocculation and dewatering. The oil sands fine tailings
fluid comes
from an inlet line 104. It is noted that the flocculation and dewatering can
be performed
using various methods. In one example, the screened tailings are subjected to
in-line
flocculation and are then transferred by pipeline to a deposition site that
can include
deposition cells in which the flocculated tailings are deposited in multiple
thin lifts. The
water drains away from the flocculated material to form a dewatered solid
material. In
another example, the screened tailings are subjected to in-line adding of an
immobilization chemical and a flocculant to form a flocculated material that
is then
transferred by pipeline to a mine pit or similar containment structure where
the solids
settle to form a settled layer and the water forms a water cap thereby forming
a
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Date Recue/Date Received 2021-09-07
permanent aquatic storage structure (PASS). Other chemical treatment and
dewatering
methods are also possible.
[00150] The pre-treatment screening is enabled by one or more of the
above-
described assemblies, systems and devices.
[00151] The method includes providing a spillbox feed tank 110 with a
tailings fluid
flow, the spillbox feed tank 110 having side walls 116 and a bottom wall 118
defining
together a tank cavity 114, the spillbox feed tank 110 also comprising an
overflow weir
120.
[00152] The method includes connecting the inlet line 104 to a
tailings inlet 112
formed in the bottom wall 118 of the spillbox feed tank 110. For instance, the
connection of the inlet line 104 to the tailings inlet 112 is configured to
form a
substantially vertical inlet flow in the tank cavity 114.
[00153] The method also includes feeding the spillbox feed tank 110
with the
tailings fluid flow so that the tailings fluid flow reaches the overflow weir
120.
[00154] The method can further include adjusting at least one of the
inlet and outlet
flow rates of the tailings fluid flowing respectively to and from the spillbox
feed tank
110. In other words, the method can further include adjusting the flow rate of
the
tailings fluid introduced into the tank cavity 114 via the tailings inlet 112
and/or of the
tailings fluid going out of the tank cavity 114 when flowing over the overflow
weir 120. It
should be noted that the adjustment can be performed in response to different
criteria,
including a measured fluid level in the tank cavity 114, a fluid losses
quantity of fluid
resulting from a running off of the screening surface 142, a measured amount
of coarse
debris on the screening surface 142, etc.
[00155] The method can thus further include measuring a level of the
tailing fluid in
the tank cavity 114. Measuring can include sensing the level of the fed
tailings with a
level sensor. Measuring can also be performed differently; for example, it can
be
performed manually by an operator. Optionally, the level sensor can be
operatively
connected to a control circuit so as to monitor the level of tailings within
the tank cavity
114 and/or within the collecting cavity 166 of the collector body 160 and
actuate certain
devices, such as valves (inlet and/or outlet valves) or inlet and/or outlet
transfer pumps,
to act in response to the sensed level when reaching given thresholds.
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[00156] The modification of the inlet and/or outlet flow rates of the
tailings fluid flow
can be performed in response to the measured level of the tailings fluid in
the tank
cavity 114.
[00157] The method further comprises discharging the tailings fluid on a
screening
device 140, the tailings fluid being discharged over the overflow weir 120 and
down to
the screening device 140. The screening device 140 has a screening surface 142
configured to allow material with a predetermined size to flow through the
screening
surface 142 and separate the coarse debris, thereby splitting the tailings
fluid into
coarse debris and a screened tailings fluid. In some implementations, the
method can
include evenly discharging the tailings fluid flow along a width L2 of the
screening
device 140 so as to maximize a screening surface efficiency. Optionally, the
method
can include discharging the tailings fluid flow onto at most about 80% of the
width of
the screening surface 142. Further optionally, the method can include
discharging the
tailings fluid flow onto at most about 85% of the width screening surface 142.
Still
further optionally, the method can include discharging the tailings fluid flow
onto at
most about 90% of the width screening surface 142.
[00158] The method can further comprise removing the coarse debris from the
screening surface 142.
[00159] As detailed above, the screening surface 142 is oriented at a first
inclination
angle al with respect to a horizontal direction. The method can further
comprise
adjusting the first inclination angle al of the screening surface 142.
[00160] The method can further comprise at least one of:
- measuring an amount of coarse debris on the screening surface 142;
- measuring a fluid level in the tank cavity 114; and
- measuring an amount of tailings fluid losses resulting from a running off
of
the screening surface 142.
[00161] For instance, the first inclination angle al of the screening
surface 142 can
be modified in response to at least one of the measured amount of coarse
debris, the
measured fluid level in the tank cavity and the measured amount of tailings
fluid losses.
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Date Recue/Date Received 2021-09-07
[00162] The method can further comprise collecting the removed debris
in a debris
collection bin 172 which can be located near the screening device 140.
[00163] The method can further comprise heating the debris collected
in the debris
collection bin 172.
[00164] The method can further comprise pumping the tailings fluid
contained in the
debris collection bin 172 back into the spillbox feed tank 110, so as to
reduce the
amount of oil sands tailings fluid losses resulting from a running off of the
screening
surface 142. Depending on the time of the year, the pumping of the tailings
fluid in the
debris collection bin 172 can be performed with or without the heating of the
debris
collection bin 172.
[00165] The method can further comprise applying vibrations to the
screening
surface 142. Thanks to the vibrations, the coarse debris retained by the
screening
surface 142 can be more easily removed from the screening surface 142.
[00166] The method can further include collecting the screened
tailings fluid in a
collector body 160 prior to transporting the screened tailings fluid for
chemical
treatment via a discharge line 108. The collector body 160 can comprise a
discharge
outlet 167 connected to the discharge line 108.
[00167] The method can further include deflecting a screened tailings
fluid flow
upstream of the collector body 160 from the discharge outlet 167. Deflection
can
reduce the amount of air flowing with the screened tailings fluid flow in the
discharge
line 108.
[00168] The method can further comprise removing debris building up in
the
collector body 164. The method can comprise pumping the debris out of the
collector
body 164 via a bottom discharge opening 165 and/or flush watering the debris
towards
the bottom discharge opening 165 and circulating flush water in a bottom
portion of the
collecting cavity 166 from a flushing inlet nozzle 50 towards the bottom
discharge
opening 165.
[00169] The method can include providing a pre-treatment screening
assembly 100
comprising at least two spillbox feed tanks 110 having each a tank cavity 114.
The
method can include adjusting the outflow rate of the tailings fluid flow
discharged over
the overflow weir 120 of at least one spillbox feed tank 110 of the different
spillbox feed
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Date Recue/Date Received 2021-09-07
tanks 110 to have a substantially similar outlet flow rate between the
different spillbox
feed tanks 110.
[00170] Each overflow weir 120 defines a height relative to a ground
on which the
pre-treatment screening assembly 100 stands. The method can further comprise
adjusting the height of at least one overflow weir 120 from the plurality of
spillbox feed
tanks 110 to obtain a substantially similar outlet flow rate between the
different spillbox
feed tanks 110.
[00171] Each spillbox feed tank 110 defines a height relative to a
ground on which
the pre-treatment screening assembly 100 stands. The method can further
comprise
adjusting the height of at least one spillbox feed tank 110 from the plurality
of spillbox
feed tanks 110 to have a substantially similar outlet flow rate between the
spillbox feed
tanks 110.
[00172] The steps of the method can be repeated or conducted for a
plurality of
pre-treatment screening assemblies 100 arranged in series or in parallel.
[00173] It should be understood that the pre-treatment screening
techniques
described herein provide screened tailings for improved and consistent mixing
with
chemicals in downstream tailings treatment operations.
[00174] In some implementations, the pre-treatment screening assembly
removes
coarse debris that would impede or inhibit chemical reactions, for instance
flocculation
reactions involving flocculant and fine solid particles in the tailings. The
pre-treatment
process can remove coarse debris having different chemical or inertial
properties
compared to the fine solid particles that are not removed.
[00175] In certain applications, the fine solid particles include clay
and can have a
certain shape, size and surface characteristics that are considered for the
chemical
selection and process design for the chemical treatment operation, and can
bestow
certain macroscopic fluid properties. In one example, the pre-treatment
screening
assembly can remove bitumen masses including slugs or mats that negatively
affect
anionic polymeric flocculant reactions with the fine solid particles in the
tailings.
[00176] In some implementations, the pre-treatment screening assembly
removes
coarse debris that would have disrupted the mixing of the chemical additive
and the
fine tailings. For instance, the pre-treatment screening assembly can remove
coarse
debris that would impede consistent mixer performance or mixer flow regime.
The pre-
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Date Recue/Date Received 2021-09-07
treatment screening assembly can also remove coarse debris that would cause
two
phase macroscopic fluid behaviour, thereby providing screened fine tailings
having one
phase macroscopic fluid behaviour. The pre-treatment screening assembly can
remove
coarse debris so that the resulting pre-treated tailings fluid is homogeneous,
or does
not contain a substantial amount of settling solid particles. The pre-
treatment screening
assembly can also remove coarse debris that would complicate or prevent
reliable
process modelling of the fluid mixing, flocculation or dewatering operations.
[00177] In some implementations, the pre-treatment screening assembly
removes
coarse debris that would damage or clog equipment.
[00178] While several implementations have been described and
illustrated herein
in relation to oil sands fine tailings, it should be understood that the
processes,
systems, devices and techniques can also be used for any other aqueous
suspensions
that include solid particles and coarse debris. Such aqueous suspensions can
comprise mining tailings resulting from mining operations, such as mature fine
tailings.
[00179] In the preceding description, the same numerical references
refer to similar
elements. Furthermore, for the sake of simplicity and clarity, not all figures
contain
references to all the components and features, and references to some
components
and features can be found in only one figure, and components and features of
the
present disclosure which are illustrated in other figures can be easily
inferred
therefrom.
[00180] Finally, while the description and drawings describe and
illustrate certain
implementations and examples of the pre-treatment techniques, the components,
geometries, arrangements and/or configurations can have various other
characteristics,
features and co-operations as those presented herein.
[00181] Several alternative implementations have been described and
illustrated
herein. The implementations of the disclosure described above are intended to
be
exemplary only. A person of ordinary skill in the art would appreciate the
features of the
individual implementations, and the possible combinations and variations of
the
components. A person of ordinary skill in the art would further appreciate
that any of
the implementations could be provided in any combination with the other
implementations disclosed herein. It is understood that the disclosure can be
embodied
in other specific forms without departing from the central characteristics
thereof. The
present examples and implementations, therefore, are to be considered in all
respects
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Date Recue/Date Received 2021-09-07
as illustrative and not restrictive, and the disclosure is not to be limited
to the details
given herein. Accordingly, while the specific implementations have been
illustrated and
described, numerous modifications come to mind. The scope of the disclosure is
therefore intended to be limited solely by the scope of the appended claims.
[00182] Any
publications, including patents, patent applications and articles,
referenced or mentioned in this specification are herein incorporated in their
entirety
into the specification, to the same extent as if each individual publication
was
specifically and individually indicated to be incorporated herein. In
addition, citation or
identification of any reference in the description of some implementations of
the
disclosure shall not be construed as an admission that such reference is
available as
prior art to the present disclosure.
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