Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
CA 02848432 2014-04-03
BITUMEN RECOVERY FROM IN-LINE TAILINGS FLOW BASED ON FLOW PROFILE
CHARACTERISTICS
FIELD
[0001] The technical field generally relates to tailings treatment and more
particularly
to recovering bitumen from an in-line tailings flow.
BACKGROUND
[0002] Various industries generate tailings. Extraction operations can extract
valuable
materials from ore using water-based extraction methods, which typically
result in
aqueous tailings streams that include water, solid particles and some residual
amount of
the valuable materials.
[0003] For example, bitumen extraction operations extract bitumen from oil
sands ore
and produce tailings streams that include water, solid particles including
coarse and fine
mineral particles, and some residual bitumen. Extraction tailings can be
pipelined from
an extraction plant to tailings containment areas where the tailings can
settle and can be
further treated in dewatering and reclamation operations.
[0004] Residual compounds, such as bitumen, can be recovered from tailings.
However, there are various challenges related to the recovery of residual
valuable
materials, such as bitumen, from tailings.
SUMMARY
[0005] In some implementations, there is provided a method for recovering
bitumen
from an in-line tailings flow, the method comprising: determining flow profile
characteristics of the in-line tailings flow; based on the flow profile
characteristics,
identifying an interface between a bitumen-rich flow component of the in-line
tailings flow
and an underlying water-rich flow component; and positioning a flow
redirection device in
accordance with the interface in order to redirect the bitumen-rich flow
component away
from the water-rich flow component.
[0006] In some implementations, the flow profile characteristics comprise a
velocity
profile.
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[0007] In some implementations, the bitumen-rich flow component that is
recovered
has a bitumen content of at least one order of magnitude greater than a
bitumen content
of the in-line tailings flow.
[0008] In some implementations, the flow redirection device comprises a
skimmer
blade having a lower plate, and the lower plate is located at or near the
interface
between the bitumen-rich flow component and the water-rich flow component.
[0009] In some implementations, the flow redirection device is located above
the
interface to promote a higher bitumen concentration in the bitumen-rich flow
component.
[00010] In some implementations, the flow redirection device is located below
the
interface to promote a higher bitumen recovery from the in-line tailings flow.
[00011] In some implementations, the flow redirection device is provided at a
fixed
position based on the interface.
[00012] In some implementations, the flow redirection device is configured so
as to be
adjustable between different positions.
[00013] In some implementations, the process also includes supplying the
bitumen-rich
flow component to a froth treatment operation or a primary extraction
operation, to
recover bitumen therefrom.
[00014] In some implementations, there is provided a system for recovering
bitumen
from an in-line tailings flow, the system comprising: a main pipe for
supplying the in-line
tailings flow; a branch pipe in fluid communication with main pipe; a flow
profiler for
determining flow profile characteristics of the in-line tailings flow and,
based on the flow
profile characteristics, identifying an interface between a bitumen-rich flow
component of
the in-line tailings flow and an underlying bitumen-poor tailings flow
component; and a
flow redirection device extending into the main pipe and located in accordance
with the
interface in order to redirect the bitumen-rich flow component into the branch
pipe.
[00015] In some implementations, the flow profiler is configured to determine
a velocity
profile of the in-line tailings flow.
[00016] In some implementations, the flow redirection device comprises a
skimmer
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blade.
[00017] In some implementations, the skimmer blade comprises: a first plate
fixed to the
main pipe and extending downwardly into the in-line tailings flow, and a
second plate
extending from a lower end of the first plate in an upstream direction, the
first and
second plates defining with an opposed wall of the main pipe a conduit for
transferring
the bitumen-rich flow component from the main pipe to the branch pipe.
[00018] In some implementations, the second plate is substantially parallel
with the
opposed wall of the main pipe.
[00019] In some implementations, the second plate is at or near the interface
between
the bitumen-rich flow component and the bitumen-poor tailings flow component.
[00020] In some implementations, there is provided a method for extracting
bitumen
from an oil sands ore, comprising: separating an oil sands ore into a bitumen
product
stream and a tailings stream comprising water, solid particles and dispersed
residual
bitumen; supplying the tailings stream toward a tailings containment area via
pipeline to
induce a pressure drop and form an in-line tailings flow having a reduced
hydraulic
pressure; determining flow profile characteristics of the in-line tailings
flow; based on the
flow profile characteristics, identifying an interface between a bitumen-rich
flow
component of the in-line tailings flow and an underlying water-rich flow
component; and
positioning a flow redirection device in accordance with the interface in
order to redirect
the bitumen-rich flow component away from the water-rich flow component.
[00021] In some implementations, there is provided a method recovering bitumen
from
tailings, comprising: producing a tailings stream from a bitumen extraction
operation, the
tailings stream comprising a dispersed mixture of bitumen, water and solids;
piping the
tailings stream to induce a pressure drop sufficient to cause separation of
the tailings
stream into a bitumen-rich flow component and a water-rich flow component;
determining a velocity profile of the tailings stream to identify a location
of the bitumen-
rich flow component within the tailings stream; based on the location of the
bitumen-rich
flow component, positioning a flow redirection device in the tailings stream
to redirect the
bitumen-rich flow component away from the water-rich flow component.
[00022] In some implementations, there is provided a use of a flow velocity
profiler for
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identifying a location within an oil sands tailings pipeline to position an in-
line bitumen
skimmer. In some implementations, the location is an interface between a
bitumen-rich
flow component and a water-rich flow component. In some implementations, the
in-line
bitumen skimmer comprises a fixed skimmer blade positioned at the interface.
[00023] In some implementations, there is provided a method for recovering a
water-
immiscible material from an in-line tailings flow, the method comprising:
determining flow
profile characteristics of the in-line tailings flow; based on the flow
profile characteristics,
identifying an interface between a water-immiscible flow component and a water
flow
component of the in-line tailings flow; and positioning a flow redirection
device in
accordance with the interface in order to redirect the water-immiscible flow
component
away from the remainder of the in-line tailings flow.
[00024] In some implementations, there is provided a method for recovering a
low-
density material from an in-line tailings flow, the low-density material
having a lower
density that water, the method comprising: determining flow profile
characteristics of the
in-line tailings flow; based on the flow profile characteristics, identifying
an interface
between a low-density flow component and an overlying a water-rich flow
component of
the in-line tailings flow; and positioning a flow redirection device in
accordance with the
interface in order to redirect the low-density flow component away from the
water-rich
flow component.
[00025] In some implementations, there is provided a method for recovering a
water-
immiscible material from an in-line aqueous suspension flow, the method
comprising:
determining flow profile characteristics of the in-line aqueous suspension
flow; based on
the flow profile characteristics, identifying an interface between a water-
immiscible flow
component and a water-rich flow component of the in-line aqueous suspension
flow; and
positioning a flow redirection device in accordance with the interface in
order to redirect
the water-immiscible flow component away from the remainder of the in-line
aqueous
suspension flow.
[00026] In some implementations, there is provided a method for recovering a
low-
density material from an in-line aqueous suspension flow, the low-density
material
having a lower density that water, the method comprising: determining flow
profile
characteristics of the in-line aqueous suspension flow; based on the flow
profile
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characteristics, identifying an interface between a low-density flow component
and an
overlying water-rich flow component of the in-line tailings flow; and
positioning a flow
redirection device in accordance with the interface in order to redirect the
low-density
flow component away from the water-rich flow component.
[00027] In some implementations, there is provided a method for separating a
multi-
phase stream, comprising: providing the multi-phase stream comprising a first
phase
and a second phase that are dispersed together; piping the multi-phase stream
to
provide a pressure drop sufficient to cause separation of the stream into a
first-phase
flow component and a second-phase flow component; determining a velocity
profile of
the multi-phase stream to identify an interface between the first-phase flow
component
and the second phase flow component; and positioning a flow redirection device
in
accordance with the interface to redirect the first-phase flow component away
from the
second-phase flow component.
[00028] In some implementations, the multi-phase stream comprises a liquid-
liquid
emulsion. In some implementations, the multi-phase stream comprises a liquid-
solid
slurry, such as tailings, which can be oil sands tailings. In some
implementations, the
multi-phase stream comprises a liquid-solid-gas slurry. In some
implementations, the
multi-phase stream comprises a solid-gas mixture.
BRIEF DESCRIPTION OF THE DRAWINGS
[00029] Fig 1 is a side cut view schematic of a system for recovering a flow
component.
[00030] Fig 2 is another side cut view schematic of a system for recovering a
flow
component.
[00031] Fig 3 is a perspective partially transparent view schematic of a
system for
recovering a flow component.
[00032] Fig 4 is a front cross-sectional view schematic of a pipe and a flow
redirection
device.
[00033] Fig 5 is a partial perspective view flow diagram.
[00034] Fig 6 is a graph of composition versus location of a flow redirection
device.
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DETAILED DESCRIPTION
[00035] In some implementations, determining flow profile characteristics of
an in-line
tailings flow can facilitate identification of a bitumen-rich flow component
and positioning
of a flow redirection device according to the location of the bitumen-rich
flow component.
Enhanced positioning of a flow redirection device can, in turn, improve
bitumen recovery
from the tailings.
[00036] Referring to Fig 1, in some implementations the bitumen recovery
system 10
includes a main pipe 12 supplying the in-line tailings flow 14, a branch pipe
16 in fluid
communication with the main pipe 12, a flow redirection device 18 extending
into the
main pipe 12, and a flow profiler 20 provided upstream of the branch pipe 16
and flow
redirection device 18. The flow profiler 20 is configured to determine flow
profile
characteristics of the in-line tailings flow 14.
[00037] Referring to Fig 2, the flow profiler 20 can be configured to
determine a velocity
profile 22 of the in-line tailings flow. The velocity profile 22 can include a
bitumen flow
profile region 24 of a bitumen-rich flow component of the in-line tailings
flow. The
bitumen-rich flow component overlies a water-rich flow component of the
tailings. The
bitumen-rich flow component can be a froth-like material including air
bubbles, bitumen,
and some water and solids. The bitumen froth-like material can tend to have a
lower
velocity compared to the underlying water-rich component of the tailings flow.
Understanding the depth and position of the bitumen flow profile region 24
allows
determining (or estimating) a location of the interface 26 between the bitumen-
rich flow
component and the underlying water-rich flow component. The flow redirection
device
18 can be located based on the estimated location of the interface 26, in
order to redirect
the bitumen-rich flow component away from the bitumen-poor water-rich tailings
flow
component and into the branch pipe 14. For instance, there is a flow interface
26 in
between the bitumen flow profile region 24 and an underlying water-rich flow
profile
region 28, and the flow redirection device 18 can be located at or near the
flow interface
26. The flow redirection device 18 can be configured to define an inlet region
having a
distance D1, which can be defined between a lower part of the flow redirection
device 18
and the upper wall of the main pipe 12. Dr can be determined based on the
distance D,
of the flow interface 26 from the upper wall of the main pipe 12. Dr can be
generally
equal to D, or be provided offset a certain distance from Di.
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[00038] The flow velocity profiler can include various different types of
velocity profiling
devices and can employ various profiling technologies. For example, the flow
velocity
profiler can be an ADFM device available from Isco, Inc., using pulse-Doppler
velocity
profiling technology to measure the velocity distribution within the flow. The
flow velocity
profiler can be a SONARtrace device available from CiDRATM, using sonar flow
technology. The flow velocity profiler can be other types of devices that
employ acoustic
sensor technology for measuring the velocity profile of the in-line tailings
flow.
[00039] In some implementations, the flow profiler and the flow redirection
device are
configured and operated to avoid disrupting the flow profile of the in-line
tailings. In
addition, the construction and the operation of the overall system can be done
to
minimize or avoid turbulence or flow eddies that would disrupt the tailings
flow both at
the flow profiler and at the flow redirection device.
[00040] As illustrated in Fig 2, the velocity flow profile can include an
irregularity or
change, indicative of the boundaries of the bitumen-rich flow component. For
example,
in some implementations the velocity flow profile can include a sudden change
in
velocity gradient indicating the interface of the bitumen-rich flow component
with the
underlying fluid. In some implementations, the velocity flow profile can
include an offset-
velocity region or a lower-velocity region in the upper part of the velocity
profile,
indicating the position of the bitumen-rich flow component. Since the bitumen-
rich flow
component can be a froth-like material composed of bitumen, air bubbles and
some
water and solids that have accumulated together, the bitumen-rich flow
component can
tend to have a lower velocity compared to the underlying water-rich flow
component. In
some implementations, the bitumen-rich flow component can display other flow
characteristics that are different from those of the underlying water-rich
flow component.
For example, due to differing fluid properties, such as density and viscosity,
the bitumen-
rich flow component can display laminar flow regime while the underlying water-
rich flow
component displays turbulent or more irregular flow regime characteristics.
The upper
bitumen-rich regime may also travel at a slower velocity than the lower
bitumen poor
regime.
[00041] The flow redirection device 18 can have various structures and
configurations.
In some implementations, the flow redirection device 18 defines a channel
having an
upstream inlet, where the inlet is sized according to Dr and the channel is in
fluid
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communication with the inlet of the branch pipe 16. In some implementations,
the flow
redirection device 18 includes a skimming member configured to skim an upper
part of
the in-line tailings flow. In some implementations, the flow redirection
device 18 is fixed
with respect to the main pipe 12. For example, the flow redirection device 18
can be
welded in place in order to define a constant distance Dr with respect to the
upper wall of
the main pipe 12. Alternatively, the flow redirection device 18 can be
connected so as to
be adjustable and thereby vary the distance Dr in response to the location of
the
interface 26. In some implementations, the flow redirection device 18 has
parts that can
be lowered or raised in order to be generally aligned with the interface
distance D, to
redirect a stream that is rich in bitumen and poor in water and solids.
[00042] Referring to Figs 1, 2 and 3 in some implementations the flow
redirection device
18 can have a fixed plate construction. The flow redirection device 18 can
include a first
plate 30 extending downwardly from the upper wall of the main pipe 12, and a
second
plate 32 extending from the lower end of the first plate 30 in an upstream
direction. The
first plate 32 can be configured to extend from the upper wall of the main
pipe 12, just
downstream of the inlet of the branch pipe 16, in an oblique manner in the
upstream
direction. The first plate 32 can extend across the entire width of the upper
part of the
main pipe 12.
[00043] Referring to Figs 3 and 4, the second plate 32 can have a width
corresponding
to the width of the main pipe at the location within the main pipe 12. The
second plate 32
can have side edges 34 that are fixed to the opposed interior walls of the
main pipe 12.
The flow redirection device 18 can be constructed such that all of the
material flowing
above the second plate 32 passes into the branch pipe 16.
[00044] Referring to Fig 5, the bitumen recovery system 10 can be used in
combination
with a bitumen extraction operation 36 that received oil sands ore 38 and
generates
bitumen product 40 and extraction tailings 42. The extraction tailings 42 are
supplied by
a tailings pump 44 toward a tailings containment area 46, which can be a
tailings pond
for example. The extraction tailings 42 initially have a relatively high
hydraulic pressure
and the residual bitumen in the tailings can be in the form of droplets
dispersed within
the tailings. The extraction tailings 42 can be considered a single-phase
slurry under
such initial high hydraulic pressures. Since the tailings containment area 46
can be
relatively remote from the bitumen extraction operation 36, the extraction
tailings 42 are
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transported long distances by pipeline 48. The in-line tailings flow decreases
in pressure
at more remote parts of the pipeline 48, facilitating air bubbles and the
dispersed
bitumen to coalesce and accumulate as a froth-like bitumen-rich flow component
overlying the rest of the tailings flow. This froth-like material can tend to
have a lower
velocity compared to the underlying water-rich component. This bitumen-rich
flow
component can be skimmed off of the rest of the tailings, supplied to a
holding tank or an
interim treatment unit 50, and eventually transported back to the bitumen
extraction
operation 36 by pipeline or truck. The recovered stream can be subjected to
settling in
order to produce a bitumen-concentrated froth. The bitumen-concentrated froth
can be
fed into the primary froth tank and then subjected to secondary froth
treatment using
diluent addition techniques.
[00045] Referring still to Fig 5, a measurement device 52 can be provided for
measuring
one or more properties of the high-pressure extraction tailings 42 proximate
to the
extraction operation 36. A second measurement device 54 can also be provided
at a
remote downstream location along the pipeline 48 for measuring one or more
properties
of the in-line tailings flow just upstream of the bitumen recovery system 10.
For example,
the second measurement device 54 can measure the pressure of the in-line
tailings flow,
which can be used to determine the pressure drop that occurred between the two
measurement devices 52 and 54. Pressure information can be used to infer
certain flow
properties of the in-line tailings flow, such as whether the pressure is low
enough for the
bitumen to accumulate and form the bitumen-rich flow component. In some
implementations, a computing unit 56 can also be provided for performing
certain
calculations based on the measured flow properties based on the measurement
devices
52 and 54, in order to estimate certain flow characteristics of the in-line
tailings flow. The
computing unit 56 can also be used to determine the position of the flow
redirection
device.
[00046] In some implementations, one or more velocity profilers can be used in
order to
determine the velocity profile of the in-line tailings flow. Multiple velocity
profiles can be
determined at a single location along the length of the pipeline 48 and/or at
different
locations along the pipeline 48.
[00047] Furthermore, the velocity profiles at multiple locations along the
length of the
pipeline 48 to determine the velocity profiles at various locations. In some
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implementations, velocity profiles can be determined along the pipeline in
order to
determine information regarding the phase separation of the bitumen- and water-
rich
components. In some implementations, velocity profile can be determined along
the
pipeline in order to determine where the phase separation has been
sufficiently
established or is sufficiently stable to provide the flow redirection device.
Thus, velocity
profiling can be performed in order to facilitate determining not only the
vertical position
of the flow redirection device at a given location, but also the location
along the length of
the pipeline. Furthermore, since the bitumen recovered from the tailing is to
be
transported back to the extraction operation, it can be advantageous to locate
the flow
redirection device as close to the extraction operation as possible as long as
adequate
phase separation has occurred.
[00048] The location of the flow redirection device can influence the
composition and
the flow rate of the stream recovered via the branch pipe. By positioning the
flow
redirection device in accordance with the flow profile characteristics of the
in-line tailings
flow, the composition and the flow rate can be manipulated and controlled.
[00049] Turning to Fig 6, the flow redirection device can be positioned at
different
distances away from the upper wall of the main pipe resulting in different
compositions of
the recovered stream. In Fig 6, the x-axis indicates the distance Dr of the
second plate
(i.e., the lower part of the flow redirection device having a plate
construction), while the
y-axis indicates the composition of an example redirected stream. It should be
noted that
the scales of the two y-axes are not necessarily the same. At Dr = 1, the
bitumen content
is relatively low although the proportion of bitumen in the recovered stream
is relatively
high. At Dr = 6, the bitumen content is relatively high but the bitumen
proportion has
decreased compared to the previous locations. At Dr = 4, the bitumen content
is quite
high and the bitumen proportion is also high. This graph illustrates the
benefits of
locating the flow redirection device at or near the interface of the bitumen-
rich and
bitumen-poor flow components, in order to increase bitumen recovery while
minimizing
the water and solids content in the recovered stream. Depending on the desired
composition of the redirected stream, the flow redirection device can be
located at
various heights within the main pipe.
[00050] In addition, the optimum position of the flow redirection device can
vary
depending on the final destination for the recovered bitumen froth. For
example, for
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recovered froth intended to be sent to a primary extraction plant, recovering
the most
bitumen at the expense of quality can be preferred. For recovered froth
intended to be
sent to a froth treatment plant (also referred to as "secondary extraction"),
a leaner cut
having lower solids and/or water at the expense of bitumen recovery can be
preferred.
Furthermore, the choice of destination for the recovered product may in part
depend on
how one transports the recovered material and the extent of oxidation in the
recovered
material.
[00051] In some implementations, empirical tests can be performed by
positioning tester
flow redirection devices at different locations (e.g., different Dr distances)
and then
determining the composition of the redirected stream, in order to determine
the flow
profile characteristics. The position of the flow redirection device can then
be determined
based on the empirically derived flow profile characteristics. For instance,
the flow
redirection device can be installed based on the tester device that gave the
highest
bitumen recovery with the lowest water/solids content. As an example, if the x-
axis of Fig
6 were from data obtained from six different tester devices, installation of
the flow
redirection device could occur at position Dr = 4 to maximize bitumen recovery
with a
reasonably low water/solids content.
[00052] In terms of compositions of the various streams, in some
implementations the
in-line tailings flow has a bitumen content of below 0.5 wt%, or below 0.2
wt%, the
bitumen-rich flow component has a bitumen content of at least an order of
magnitude
greater that the in-line tailings flow, for example from 2 wt% to 5 wt%. The
bitumen-rich
flow component can also have a composition that easily concentrates upon
settling to
produce a bitumen froth having a suitable bitumen concentration for
incorporation into
the froth treatment operations, for example about 40 wt% to about 45 wt%.
Depending
on the bitumen content, the recovered stream can be supplied to various parts
of the oil
sands operation having inputs with similar compositions.
[00053] In some implementations, various types of tailings streams can be
treated in
order to recover valuable materials that have a tendency to form discrete in-
line flow
components. For example, the tailings streams can include water, solid mineral
particles,
gas bubbles, and valuable materials including hydrocarbons or other water-
immiscible
compounds. Water-immiscible compounds that tend to form a discrete in-line
flow
component overlying or underlying the water-rich flow component of the
tailings can be
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recovered using various techniques described herein. Low-density materials
that tend to
rise and form a discrete in-line flow component overlying or underlying the
water-rich
flow component can also be recovered using various techniques described
herein. The
discrete in-line flow component can be detected using a flow profiler and the
flow
redirection device can then be positioned accordingly.
[00054] In some implementations, various other in-line multi-phase flows can
be
separated can be treated in order to recover valuable materials that have a
tendency to
form discrete in-line flow components. In-line liquid-liquid flows, such as
hydrocarbon-
water flows, can be separated using techniques described herein where a flow
redirection device is positioned in an upper or lower part of the main pipe to
redirect one
of the immiscible liquids away from the other. In-line liquid-solid flows can
also be
separated using techniques described herein wherein a flow redirection device
is
positioned in an upper or lower part of the main pipe to redirect a solids-
rich or a solids-
poor flow component away from the rest of the stream. In liquid-solid
scenarios, when
the solids are of various different sizes which tend to separate into
different areas of the
flow (e.g., coarse heavier solids at the bottom and lighter finer solids at
the top), the flow
redirection device can be positioned in order to separate a fines-rich flow
component
from a coarse-rich flow component. In-line gas-solid flows can also be
separated using
techniques described herein.
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