Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
CA 02633018 2008-05-30
AN APPARATUS AND A METHOD FOR SEPARATING
A FLOTATION FROTH
TECHNICAL FIELD
An apparatus and a method for separating a flotation froth into a plurality of
components.
BACKGROUND OF THE INVENTION
Oil sand is essentially a matrix of bitumen, solid mineral matter, and water.
The bitumen portion of oil sand consists of viscous hydrocarbons which behave
much like a solid at normal in situ temperatures and which act as a binder for
the other portions of
the oil sand matrix.
The solid mineral matter portion of oil sand consists of sand, rock, silt and
clay.
Coarse solid material is generally considered to include solid mineral matter
having a particle size
greater than or equal to about 44 microns, while fine solid material is
generally considered to
include solid mineral matter having a particle size less than about 44
microns. Sand and rock are
therefore generally present in oil sand as coarse solid material, due to the
relatively large size of
individual particles of sand and rock. Silt and clay are generally present in
oil sand as fine solid
material, due to the relatively small size of individual particles of silt and
clay.
The water portion of oil sand consists essentially of a film of connate water
surrounding the coarse solid material in the oil sand matrix, and may also
contain particles of solid
mineral matter within it.
A typical deposit of oil sand will contain about 10 percent to about 12
percent
bitumen and about 3 percent to about 6 percent water, with the remainder of
the oil sand being
made up of solid mineral matter. Of the total amount of solid mineral matter,
good quality oil sand
deposits typically contain about 14 percent to about 20 percent fine solid
material and about 80
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percent to about 86 percent coarse solid material. Poorer quality oil sand
deposits may contain 30
percent or more fine solid material. Oil sand extracted from the Athabasca
area near Fort
McMurray, Alberta, Canada averages about 11 percent bitumen, about 5 percent
water and about
84 percent solid mineral matter, with about 15 percent to about 20 percent of
the solid mineral
matter being fine solid material.
Oil sand deposits are mined for the purpose of recovering bitumen from the oil
sand, which bitumen is then upgraded to synthetic crude oil. Several different
approaches to
recovering the bitumen from the oil sand have been developed.
A conventional approach to recovering bitumen from oil sand is the use of a
``hot
water process" in which aggressive thermal action, aggressive chemical action
and aggressive
mechanical action are used to liberate and separate bitumen from the oil sand.
The hot water process includes several steps. In a first step, oil sand is
conditioned
by mixing the oil sand with hot water in a conditioning vessel which
vigorously agitates the
resulting slurry in order to completely disintegrate the oil sand. Sodium
hydroxide (caustic) may
be added to the slurry during conditioning to maintain a slightly basic pH in
the conditioning
vessel, which enhances the disintegration of the oil sand by chemically
dispersing the fine solid
material contained in the oil sand.
In a second step, the slurry of disintegrated oil sand undergoes a primary
separation
process in a primary separation vessel. The primary separation process
separates the slurry into
three streams. A solids stream, containing relatively large amounts of coarse
solid material and
relatively small amounts of residual bitumen and fine solid material, settles
out from the slurry and
is withdrawn from a lower portion of the primary separation vessel. A bitumen
froth stream,
containing relatively large amounts of air entrained bitumen and relatively
small amounts of solid
mineral matter, floats to the top of the slurry and is withdrawn from an upper
portion of the
primary separation vessel. A middlings stream, containing a relatively small
amount of residual
bitumen and a relatively large amount of fine solid material, is withdrawn
from an intermediate
portion of the primary separation vessel.
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In a third step, the middlings stream is treated or scavenged, typically by
froth
flotation, to recover a portion of the residual bitumen contained therein as a
flotation froth. The
flotation froth which is recovered from the middlings stream may be returned
to the primary
separation process or may be combined with the bitumen froth stream.
In a fourth step, the bitumen froth stream is subjected to a froth treatment
process in
which solid mineral matter and water is separated from the bitumen froth to
produce a "clean" and
"dry" bitumen froth.
The solids stream which is produced in the second step is typically dewatered
and/or disposed of as backfill or in berms as coarse tailings. In some
circumstances, it may be
feasible to recover some of the residual bitumen from the solids stream by
froth flotation, as a
flotation froth, before the solids stream is disposed of.
Another approach to recovering bitumen from oil sand is directed at "solids
rejection" as a primary separation technique, in which oil sand is separated
into a bitumen froth
stream and a solids stream, without the production of a middlings stream.
One example of the solids rejection approach is described in Canadian Patent
Application No. 2,030,934 (Strand), Canadian Patent Application No. 2,124,199
(Strand),
Canadian Patent No. 2,123,076 (Strand et al), Canadian Patent Application No.
2,512,106
(Strand), and Canadian Patent Application No. 2,524,110 (Strand), all of which
are assigned to
Bitmin Resources Inc. (the "Bitmin Process").
In the Bitmin Process, a countercurrent separator drum containing a spiral
ribbon
and mixer elements is utilized for primary separation of the oil sand. Oil
sand is gently rolled from
one end to the other end of the separator drum while warm water circulates in
the opposite
direction. The pH of the warm water in the separator drum is maintained at no
greater than about 7
in order to limit the chemical dispersal of fine solid material contained in
the oil sand.
Two streams are then removed from the opposite ends of the separator drum. A
solids stream containing solid mineral matter (including coarse solid material
and a small amount
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of fine solid material), water and a small amount of residual bitumen is
removed from one end of
the separator drum, and a bitumen froth stream containing bitumen, solid
mineral matter (including
fine solid material and a small amount of coarse solid material) and water is
removed from the
other end of the separator drum.
The solids stream is filtered using a horizontal belt filter apparatus to
produce
dewatered coarse tailings which may be disposed of as backfill, in berms, or
in some other manner.
In some circumstances, it may be feasible to recover some of the residual
bitumen from the solids
stream by froth flotation, as a flotation froth, before the solids stream is
disposed of.
The bitumen froth stream is further processed in a froth separator to produce
bitumen froth as a product stream and fine tailings containing a small amount
of residual bitumen.
The fine tailings are treated, typically by froth flotation, to recover some
of the residual bitumen
from the fine tailings as a flotation froth. The fine tailings are then
dewatered in a thickener,
following which all or a portion of the dewatered fine tailings may be co-
filtered with the coarse
tailings to produce non-segregating tailings comprising the coarse tailings
and the fine tailings, or
the fine tailings may be disposed of in some other manner.
A second example of the solids rejection approach is described in Canadian
Patent
No. 2,332,207 (Lavender et al) and Canadian Patent No. 2,358,805 (Lavender et
al), both of which
are assigned to TSC Company Ltd. (the "TSC Process").
In the TSC Process, an assembly of three hydrocyclone packs or clusters
arranged
countercurrently in series are utilized for primary separation of the oil
sand. Two streams are
removed from the hydrocyclone assembly. A solids stream containing solid
mineral matter
(including coarse solid material and some fine solid material), water and a
small amount of
residual bitumen is removed as an underflow stream from the third
hydrocyclone, and a bitumen
froth stream containing bitumen, solid mineral matter (including fine solid
material and some
coarse solid material) and water is removed as an overflow stream from the
first hydrocyclone.
The solids stream is filtered using a horizontal belt filter apparatus to
produce
dewatered coarse tailings which may be disposed of as backfill or in some
other manner.
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Conceivably, in some circumstances, it may be feasible to recover some of the
residual bitumen
from the solids stream by froth flotation, as a flotation froth, before the
solids stream is disposed
of.
The bitumen froth stream is further processed in a "product separator" to
produce
bitumen froth as a product stream and fine tailings containing a small amount
of residual bitumen.
The fine tailings are recycled back to the hydrocyclone assembly for further
processing in the
hydrocyclone assembly. Alternatively, in some circumstances it may be feasible
to recover some
of the residual bitumen from the solids stream by froth flotation, as a
flotation froth, thereby
avoiding recycling of the fine tailings.
Other approaches to recovering bitumen from oil sand may be based upon
variations of the hot water process, the Bitmin Process and the TSC Process,
or may be based upon
other technologies.
Regardless of the approach which is used to recover bitumen from oil sand, it
may
be necessary or desirable in some circumstances to recover residual bitumen
from a middlings
stream or from one or more of the solids streams which are produced by the
bitumen recovery
process. Froth flotation techniques may often be effective for treating such
middlings or solids
streams to recover some or all of the residual bitumen therefrom, as a
flotation froth.
A flotation froth comprising residual bitumen which is recovered from a
middlings
stream or from a solids stream produced by a bitumen recovery process may
typically contain
(approximately or about) between 4 percent and 25 percent bitumen by weight,
between 65 percent
and 95 percent water by weight, between 1 percent and 20 percent solid mineral
matter by weight,
and between 30 percent and 60 percent air by volume.
The significant amount of air which is typically contained within the
flotation froth
often results in difficulties being encountered in handling and processing the
flotation froth.
Aerated flotation froth is often difficult to pump and may cause air locking
problems in pump
apparatus. In addition, pumping aerated flotation froth is typically
relatively inefficient due to
energy losses resulting from aeration compression. As a result of these
difficulties, operators may
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dilute the flotation froth with water before handling in order to minimize the
effects of aeration on
the flotation froth. Diluting the flotation froth results in a lower grade of
froth, which typically
requires additional processing in order to achieve a useable bitumen product.
For example, diluted flotation froth may need to be recycled through bitumen
recovery apparatus, and recycling of product streams generally reduces the
processing capacity of
apparatus such as separation vessels and flotation apparatus.
In addition to difficulties relating to aeration of the flotation froth,
flotation froth
also typically contains significant amounts of solid mineral matter and water
relative to the amount
of bitumen contained therein. As indicated above, even without dilution the
concentration of
bitumen in a typical flotation froth is less than 20 percent, and the amount
by weight of solid
mineral matter may exceed the amount by weight of bitumen. Due to its
composition, it may be
difficult to increase the concentration of bitumen relative to solid mineral
matter and water in a
flotation froth using conventional bitumen froth cleaning techniques.
There remains a need for apparatus and methods which are useful for cleaning
flotation froth to increase the concentration of bitumen therein relative to
solid mineral matter and
water. There also remains a need for apparatus and methods for cleaning
flotation froth which
may also be useful for deaerating flotation froth.
SUMMARY OF THE INVENTION
References in this document to orientations, to operating parameters, to
ranges, to
lower limits of ranges, and to upper limits of ranges are not intended to
provide strict boundaries
for the scope of the invention, but should be construed to mean
"approximately" or "about" or
"substantially", within the scope of the teachings of this document, unless
expressly stated
otherwise.
The present invention includes an apparatus and a method for separating a
flotation
froth into a water component, a bitumen component, and in preferred
embodiments, an air
component. The invention results in cleaning and/or deaeration of the
flotation froth.
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The flotation froth is comprised of between 4 percent and 25 percent bitumen
by
weight and between 65 percent and 95 percent water by weight.
The flotation froth may be further comprised of an amount of a flotation aid
such as
air. The amount of the flotation aid may be any amount. As a non-limiting
example, the flotation
froth may be comprised of between 30 percent and 60 percent air by volume. If
the flotation aid is
not present in large concentrations, or if for any reason it is not considered
necessary or desirable
to separate the air component from the flotation froth, the invention may be
used to separate the
flotation froth only into the water component and the bitumen component.
Due to the typical manner of production of the flotation froth, the air
contained in
the flotation froth may tend to be present in relatively larger bubbles or
individual volumes than air
which may be contained in a primary froth obtained from an oil sands primary
recovery process.
As a result, separation of the flotation froth to separate the air component
therefrom may tend to be
more effective and/or efficient than a similar method for separating primary
froth to remove an air
component therefrom.
The flotation froth may be further comprised of an amount of solid mineral
matter.
The amount of the solid mineral matter may be any amount. As a non-limiting
example, the
flotation froth may be comprised of between 1 percent and 20 percent solid
mineral matter by
weight.
The water component of the flotation froth is a component derived from the
flotation froth which contains a sufficient concentration of water so that it
may be characterized as
the water component, as distinct from the air component and the bitumen
component. The water
component may therefore contain amounts of air, bitumen, solid mineral matter
and/or other
substances.
The bitumen component of the flotation froth is a component derived from the
flotation froth which contains a sufficient concentration of bitumen so that
it may be characterized
as the bitumen component, as distinct from the air component and the water
component. The
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bitumen component may therefore contain amounts of air, water, solid mineral
matter and/or other
substances.
The air component of the flotation froth is a component derived from the
flotation
froth which contains a sufficient concentration of air so that it may be
characterized as the air
component, as distinct from the water component and the bitumen component. The
air component
may therefore contain amounts of water, bitumen, solid mineral matter and/or
other substances.
In one apparatus aspect, the invention is a separator for separating a
flotation froth
into a water component and a bitumen component, wherein the flotation froth is
comprised of
between about 65 percent and about 95 percent water by weight, and wherein the
flotation froth is
further comprised of between about 4 percent and about 25 percent bitumen by
weight, the
separator comprising:
(a) a plurality of substantially parallel plates having a first end and a
second end,
wherein the plates are inclined at an inclination angle relative to a
horizontal
reference, wherein the first end of the plates is above the second end of the
plates,
and wherein the plates are separated from each other by a plate separation
distance,
thereby providing inclined channels between the plates;
(b) a flotation froth inlet communicating with the first end of the plates,
for introducing
the flotation froth into the separator;
(c) a water component outlet communicating with the second end of the plates,
for
discharging the water component from the separator; and
(d) a bitumen component outlet communicating with the second end of the
plates, for
discharging the bitumen component from the separator, wherein the bitumen
component outlet is positioned above the water component outlet.
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The separator is preferably further comprised of an air component outlet
communicating with the first end of the plates, for discharging an air
component of the flotation
froth from the separator.
Each of the inclined channels defines a profile in a transverse direction. The
profile
may be substantially planar and horizontal or may be comprised of at least one
peak and at least
one trough. The at least one peak and the at least one trough may be provided
by the shape of the
plates, by the orientation of the plates, by the configuration of the plates,
or in any other suitable
manner.
In some embodiments, each of the plates is substantially horizontal in the
transverse
direction and is comprised of a plurality of discontinuities so that the
profile of the inclined
channels is comprised of a series of alternating peaks and troughs. In some
embodiments, each of
the plates is substantially planar and is tilted in the transverse direction
at a transverse inclination
angle relative to a transverse horizontal reference so that the profile of the
inclined channels is
comprised of a single peak and a single trough.
The plates may be substantially parallel so that the plate separation distance
between two adjacent plates is substantially constant.
The separator may be further comprised of spacers for maintaining the plate
separation distance between the plates. The plate separation distance between
each pair of
adjacent plates is preferably substantially the same, but in some
applications, a different plate
separation distance may be provided between pairs of adjacent plates.
In embodiments in which the profile of the inclined channels is comprised of a
series of peaks and troughs, the plates may be sawtooth shaped (i.e., with
pointed peaks and
pointed troughs), corrugated (i.e., with flat peaks and flat troughs),
undulated (i.e., with curved
peaks and curved troughs), or may be any other shape in order to provide the
peaks and troughs.
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A purpose of the peaks and troughs may be to facilitate collecting of the
bitumen
component in the peaks and collecting of the water component in the troughs,
thereby providing
some separation of the bitumen component and the water component in the
inclined channels.
The distance between adjacent peaks in a series of alternating peaks and
troughs
may be any distance which is suitable for facilitating some separation of the
bitumen component
and the water component in the inclined channels. In some embodiments, the
plates may be
configured so that the distance between adjacent peaks is between 20
centimeters and 30
centimeters. In some embodiments, the plates may be configured so that the
distance between
adjacent peaks is 25 centimeters.
In embodiments in which the profile of the inclined channels is comprised of a
single peak and a single trough, the peak may be defined by a first side of
the separator in the
transverse direction and the trough may be defined by a second side of the
separator in the
transverse direction. In such embodiments the transverse inclination angle may
be any angle
which is suitable for facilitating some separation of the bitumen component
and the water
component in the inclined channels. In some embodiments, the plates may be
configured so that
the transverse inclination angle is between 5 degrees and 60 degrees. In some
embodiments, the
plates may be configured so that the transverse inclination angle is between
10 degrees and 20
degrees.
Each of the plates has an upper surface and a lower surface. One or both of
the
surfaces of the plates may be relatively smooth and/or one or both of the
surfaces of the plates may
be relatively rough. Providing the plates with relatively smooth surfaces may
assist in minimizing
sticking of the flotation froth or its components to the plates. Providing the
plates with relatively
rough surfaces may assist in promoting separation of the flotation froth into
its components. In
some embodiments, both surfaces of the plates are relatively smooth.
The separator may be further comprised of a feed box adjacent to the first end
of the
plates, for containing the flotation froth which is introduced into the
separator. The feed box may
extend above the first end of the plates to assist in providing that the first
end of the plates is
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submerged in the flotation froth. The feed box may also function as a surge
tank in providing a
surge volume to reduce the effects of a fluctuating supply of the flotation
froth to the separator.
The separator may be further comprised of a feed box level sensor associated
with
the feed box, for sensing a level of the flotation froth in the feed box. The
feed box level sensor
may be comprised of any sensing device or apparatus which is capable of
sensing the level of the
flotation froth in the feed box. As non-limiting examples, the feed box level
sensor may be
comprised of an electrical sensor, a mechanical sensor, an electro-hydraulic
sensor, or a hydro-
mechanical sensor. In some embodiments, the feed box level sensor may be
comprised of a float.
The feed box level sensor may also be comprised of a visual sensing device
such as a sight glass.
The separator may be further comprised of a discharge box adjacent to the
second
end of the plates, for collecting the water component and the bitumen
component before they are
discharged from the separator. The discharge box may extend below the second
end of the plates
so that the discharge box can provide for some gravity separation of the water
component and the
bitumen component after the flotation froth has passed through the inclined
channels.
The water component outlet and the bitumen component outlet may communicate
with the discharge box.
The separator may be further comprised of a discharge box interface sensor
associated with the discharge box, for sensing an interface between the water
component and the
bitumen component in the discharge box. The discharge box interface sensor may
be comprised of
any sensing device or apparatus which is capable of sensing the interface
between the water
component and the bitumen component in the discharge box. As non-limiting
examples, the
discharge box interface sensor may be comprised of an electrical sensor, a
mechanical sensor, an
electro-hydraulic sensor, or a hydro-mechanical sensor. In some embodiments,
the discharge box
interface sensor may be comprised of a capacitance probe or a segmented
dielectric probe. The
discharge box interface sensor may also be comprised of a visual sensing
device such as a sight
glass.
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The separator may be further comprised of a water component outlet flow
regulator
associated with the water component outlet, for controlling the discharging of
the water component
from the separator. The water component outlet flow regulator may be comprised
of any device or
apparatus which is capable of controlling the passing of the water component
through the water
component outlet. As a first non-limiting example, the water component outlet
flow regulator may
be comprised of a variable speed pump or a variable output pump. As a second
non-limiting
example, the water component outlet flow regulator may be comprised of a
valve. The water
component outlet flow regulator may be manually controlled, semi-automatically
controlled, or
automatically controlled.
The separator may be further comprised of a bitumen component outlet flow
regulator associated with the bitumen component outlet, for controlling the
discharging of the
bitumen component from the separator. The bitumen component outlet flow
regulator may be
comprised of any device or apparatus which is capable of controlling the
passing of the bitumen
component through the bitumen component outlet. As a first non-limiting
example, the bitumen
component outlet flow regulator may be comprised of a variable speed pump or a
variable output
pump. As a second non-limiting example, the bitumen component outlet flow
regulator may be
comprised of a valve. The bitumen component outlet flow regulator may be
manually controlled,
semi-automatically controlled, or automatically controlled.
The separator may be further comprised of a flotation froth inlet flow
regulator
associated with the flotation froth inlet, for controlling the introducing of
the flotation froth into
the separator. The flotation froth inlet flow regulator may be comprised of
any device or apparatus
which is capable of controlling the passing of the flotation froth through the
flotation froth inlet.
As a first non-limiting example, the flotation froth inlet flow regulator may
be comprised of a
variable speed pump or a variable output pump. As a second non-limiting
example, the flotation
froth inlet flow regulator may be comprised of a valve. The flotation froth
inlet flow regulator may
be manually controlled, semi-automatically controlled, or automatically
controlled.
The purpose of the water component outlet flow regulator, the bitumen
component
outlet flow regulator, and the flotation froth inlet flow regulator is to
facilitate control of the levels
in the separator of the flotation froth, the water component and the bitumen
component.
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In some embodiments, the separator is comprised of the water component outlet
flow regulator, the bitumen component outlet flow regulator and the flotation
froth inlet flow
regulator, so that control of the levels in the separator of the flotation
froth, the water component
and the bitumen component is facilitated by controlling the introducing of the
flotation froth into
the separator and by controlling the discharging of the water component and
the bitumen
component from the separator.
In some embodiments, the separator is comprised of the water component outlet
flow regulator and the bitumen component outlet flow regulator, but does not
include the flotation
froth inlet flow regulator. In such embodiments, control of the levels in the
separator of the
flotation froth, the water component and the bitumen component is facilitated
by controlling the
discharging of the water component and the bitumen component from the
separator.
The separator may be further comprised of a controller for controlling the
operation
of the separator. The controller may be operatively connected with the flow
regulators associated
with the separator and may therefore control the operation of the flow
regulators.
In some embodiments, the controller may be operatively connected with and
control
the operation of the flotation froth inlet flow regulator, the water component
outlet flow regulator
and the bitumen component outlet flow regulator.
In some embodiments in which the separator does not include the flotation
froth
inlet flow regulator, the controller may be operatively connected with and may
control the
operation of the water component outlet flow regulator and the bitumen
component outlet now
regulator.
The separator may be operated manually, semi-automatically or automatically so
that the interface between the water component and the bitumen component in
the discharge box is
maintained above the water component outlet and below the bitumen component
outlet, and/or the
separator may be operated manually, semi-automatically or automatically so
that the level of the
flotation froth in the feed box is maintained above the first end of the
plates.
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In some embodiments in which the separator is comprised of the controller, the
controller may be configured to receive data from the feed box level sensor
and the discharge box
interface sensor and to use the data to control the flow regulators which are
associated with the
separator.
In some embodiments in which the separator is comprised of the controller, the
controller may be configured to receive data from the feed box level sensor
and the discharge box
interface sensor and to use the data to control the water component outlet
flow regulator and the
bitumen component outlet flow regulator in order to maintain the interface
between the water
component and the bitumen component in the discharge box above the water
component outlet and
below the bitumen component outlet, and/or in order to maintain the level of
the flotation froth in
the feed box above the first end of the plates.
The controller may be comprised of any device, apparatus, or combination of
devices and apparatus which is capable of performing the intended functions of
the controller and
which is compatible with the device and/or apparatus with which it is
associated. As non-limiting
examples, the controller may be comprised of one or more electric, electronic,
mechanical, electro-
mechanical, hydraulic, electro-hydraulic or pneumatic devices or apparatus.
The plates may be constructed of any material or combination of materials
which is
suitable for use in processing flotation froth. The plates may have relatively
smooth surfaces or
may have roughened surfaces.
The inclination angle of the plates may be any angle which will facilitate
passing of
the flotation froth through the inclined channels while providing a desired
residence time of the
flotation froth in the inclined channels or projected area of the separator.
The plate separation
distance may be any distance between the plates which will facilitate passing
of the flotation froth
through the inclined channels without significant plugging of the inclined
channels by the
components of the flotation froth. The plate separation distance may be
minimized in order to
maximize the surface area to volume ratio of the flotation froth as it passes
through the inclined
channels.
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The minimum plate separation distance for avoiding plugging of the inclined
channels may be dependent in part upon the inclination angle of the plates.
For example, the plate
separation distance may possibly be reduced without increasing the risk of
plugging of the inclined
channels, if the inclination angle is correspondingly increased, and the plate
separation distance
may need to be increased if the inclination angle is reduced in order to avoid
increasing the risk of
plugging of the inclined channels.
In some embodiments, the inclination angle of the plates may be between 15
degrees and 60 degrees. In some embodiments, the inclination angle of the
plates may be between
25 degrees and 35 degrees.
As used herein, the plate separation distance is the space between opposing
adjacent
surfaces of two adjacent plates, measured in a direction which is normal to
the plate surfaces. In
some embodiments, the plate separation distance may be between 60 millimeters
and 90
millimeters. In some embodiments, the plate separation distance may be between
60 and 80
millimeters. In some embodiments, the plate separation distance may be between
60 millimeters
and 70 millimeters.
In some embodiments, the inclination angle of the plates may be between 15
degrees and 60 degrees and the plate separation distance may be between 60
millimeters and 90
millimeters. In some embodiments, the inclination angle of the plates may be
between 25 degrees
and 35 degrees and the plate separation distance may be between 60 millimeters
and 80
millimeters. In some embodiments, the inclination angle of the plates may be
between 25 degrees
and 35 degrees and the inclination angle may be between 60 millimeters and 70
millimeters.
The separator may be sized to separate a desired volume and/or flowrate of the
flotation froth, and/or to provide a desired residence time and/or separation
of the flotation froth.
The separator may be comprised of any number of plates which is sufficient to
accommodate the
desired volume and/or flowrate of the flotation froth. The plates, the feed
box and the discharge
box may be of any size or dimension which is sufficient to accommodate the
desired volume
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CA 02633018 2008-05-30
and/or flowrate of the flotation froth and which is sufficient to accommodate
the desired residence
time and/or separation of the flotation froth.
The separator may be further comprised of a vessel for containing and/or
comprising features of the separator. The vessel may contain the plates. The
feed box and/or the
discharge box may be integrally formed with or connected with the vessel. The
vessel may be any
suitable shape. By way of non-limiting examples, the vessel may be generally
cylindrical or
generally rectangular.
In some embodiments where the vessel is generally rectangular, the vessel may
have a height, a width and a length. The height and the width of the vessel
may define a cross-
sectional area of the vessel. In some embodiments, the cross-sectional area of
the vessel is
substantially square. A ratio of the length of the vessel to the cross-
sectional area of the vessel
may be at least about 1:1 m/m2.
The method of the invention may be performed using a separator according to a
separator embodiment of the invention or with any other suitable apparatus
which is compatible
with the performance of the method.
In one method aspect, the invention is a method of separating a flotation
froth into a
water component and a bitumen component, the method comprising:
(a) providing a separator comprising a plurality of substantially parallel
plates having a
first end and a second end, wherein the plates are inclined at an inclination
angle
relative to a horizontal reference, wherein the first end of the plates is
above the
second end of the plates, and wherein the plates are separated from each other
by a
plate separation distance, thereby providing inclined channels between the
plates;
(b) introducing the flotation froth into the separator adjacent to the first
end of the
plates so that the flotation froth passes through the inclined channels from
the first
end of the plates toward the second end of the plates, wherein the flotation
froth is
comprised of between about 65 percent and about 95 percent water by weight,
and
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CA 02633018 2010-09-29
wherein the flotation froth is further comprised of between about 4 percent
and
about 25 percent bitumen by weight; and
(c) separately discharging the water component and the bitumen component from
the
separator adjacent to the second end of the plates.
The method is preferably further comprised of discharging an air component of
the
flotation froth from the separator adjacent to the first end of the plates.
The method may be performed in a continuous manner or in a batch manner.
The method generally may be performed at any temperature which facilitates
passing of the flotation froth through the inclined channels and separation of
the flotation froth into
the air component, the water component and the bitumen component.
The method may be performed at a temperature between a low temperature limit
and a high temperature limit. The low temperature limit for performing the
method may be the
lowest temperature which facilitates passing of the flotation froth through
the inclined channels
and separation of the flotation froth into the air component, the water
component and the bitumen
component. The high temperature limit for performing the method may be the
highest temperature
at which the method may be performed without causing excessive vaporization of
hydrocarbons
which are contained in the flotation froth.
As one non-limiting example, the flotation froth which is introduced into the
separator may have a temperature of between 35 degrees Celsius and 70 degrees
Celsius. As a
second non-limiting example, the flotation froth which is introduced into the
separator may have a
temperature of between 40 degrees Celsius and 60 degrees Celsius.
The separator may be further comprised of a feed box adjacent to the first end
of the
plates, the feed box may extend above the first end of the plates, and the
method may be further
comprised of maintaining a level of the flotation froth in the feed box above
the first end of the
plates.
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CA 02633018 2008-05-30
The separator may be further comprised of a discharge box adjacent to the
second
end of the plates, and the method may be further comprised of collecting the
water component and
the bitumen component in the discharge box before discharging the water
component and the
bitumen component from the separator. The discharge box may extend below the
second end of
the plates.
The method may be further comprised of maintaining an interface between the
water component and the bitumen component in the discharge box so that the
interface is above
the location of discharging of the water component from the separator and so
that the interface is
below the location of discharging the bitumen component from the separator.
The separator may be further comprised of a water component outlet
communicating with the discharge box, the separator may be further comprised
of a bitumen
component outlet communicating with the discharge box, the bitumen component
outlet may be
positioned above the water component outlet, and the method may be further
comprised of
maintaining an interface between the water component and the bitumen component
in the
discharge box above the water component outlet and below the bitumen component
outlet.
The separator may be further comprised of a flotation froth inlet
communicating
with the first end of the plates. The separator may be further comprised of an
air component outlet
communicating with the first end of the plates.
Maintaining the interface between the water component and the bitumen
component
in the discharge box and maintaining the level of the flotation froth in the
feed box may be
comprised of at least one of controlling the introducing of the flotation
froth into the separator,
controlling the discharging of the water component from the separator, and
controlling the
discharging of the bitumen component from the separator.
In some embodiments, the introducing of the flotation froth into the separator
may
not be controlled. In some embodiments, maintaining the interface between the
water component
and the bitumen component in the discharge box and maintaining the level of
the flotation froth in
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CA 02633018 2008-05-30
the feed box may be comprised of controlling the discharging of the water
component from the
separator and controlling the discharging of the bitumen component from the
separator.
Controlling the introducing of the flotation froth into the separator,
controlling the
discharging of the water component from the separator, and/or controlling the
discharging of the
bitumen component from the separator may be performed manually, semi-
automatically or
automatically.
The separator may be further comprised of a controller for controlling the
introducing of the flotation froth into the separator, controlling the
discharging of the water
component from the separator, and/or controlling the discharging of the
bitumen component from
the separator.
The separator may be further comprised of a feed box level sensor, associated
with
the feed box, for sensing the level of the flotation froth in the feed box.
The separator may be
further comprised of a discharge box interface sensor, associated with the
discharge box, for
sensing the interface between the water component and the bitumen component in
the discharge
box.
The controller may be configured to receive data from the feed box level
sensor and
the discharge box interface sensor and to use the data to control the
operation of the separator in
order to maintain the interface between the water component and the bitumen
component in the
discharge box and/or in order to maintain the level of the flotation froth in
the feed box.
The method may be further comprised of disposing of at least a portion of the
water
component. The water component may be disposed of as tailings and/or as waste
water.
The method may be further comprised of subjecting at least a portion of the
water
component to an oil sands secondary recovery process in order to recover
bitumen from the water
component. The oil sands secondary recovery process may be comprised of any
process which is
compatible with the composition of the water component. The oil sands
secondary recovery
process may be a process within the overall oil sands recovery process which
has produced the
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CA 02633018 2008-05-30
flotation froth, so that subjecting the water component to the oil sands
secondary recovery process
may be comprised of recycling the water component to an earlier step of the
overall oil sands
recovery process. Alternatively, the oil sands secondary recovery process may
be a process which
is independent of the overall oil sands recovery process which has produced
the flotation froth.
The method may be further comprised of combining at least a portion of' the
bitumen component with a bitumen product obtained from an oil sands primary
recovery process.
The oil sands primary recovery process may be a hot water process, a solids
rejection process, or
some other type of process. The oil sands primary recovery process may be a
process within the
overall oil sands recovery process which has produced the flotation froth or
may be a process
which is independent of the overall oil sands recovery process which has
produced the flotation
froth.
The method may be further comprised of recycling at least a portion of the
bitumen
component to an oil sands primary recovery process. The oil sands primary
recovery process may
be a hot water process, a solids rejection process, or some other type of
process. The oil sands
primary recovery process may be a process within the overall oil sands
recovery process which has
produced the flotation froth or may be a process which is independent of the
overall oil sands
recovery process which has produced the flotation froth.
BRIEF DESCRIPTION OF DRAWINGS
Embodiments of the invention will now be described with reference to the
accompanying drawings, in which:
Figure 1 is a schematic cross-section side view and partial pictorial view of
a
separator according to an embodiment of the invention.
Figure 2 is a schematic transverse cross-section view of the vessel portion of
the
separator of Figure 1, taken along line 2-2 in Figure 1, in which the profile
of the inclined channels
is comprised of a series of alternating peaks and troughs.
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CA 02633018 2008-05-30
Figure 3 is a schematic transverse cross-section view of an isolated portion
of three
inclined plates defining two inclined channels, in which the profile of the
inclined channels is
comprised of a series of alternating sawtooth shaped peaks and troughs (i.e.,
pointed peaks and
pointed troughs) which are formed by discontinuities in the plates.
Figure 4 is a schematic transverse cross-section view of an isolated portion
of three
inclined plates defining two inclined channels, in which the profile of the
inclined channels is
comprised of a series of alternating corrugated peaks and troughs (i.e., flat
peaks and flat troughs)
which are formed by discontinuities in the plates.
Figure 5 is a schematic transverse cross-section view of an isolated portion
of three
inclined plates defining two inclined channels, in which the profile of the
inclined channels is
comprised of a series of alternating undulated peaks and troughs (i.e., curved
peaks and curved
troughs) which are formed by discontinuities in the plates.
Figure 6 is a schematic transverse cross-section view of the vessel portion of
the
separator of Figure 1, taken along line 2-2 in Figure 1, in which the profile
of the inclined channels
is comprised of a single peak and a single trough.
Figure 7 is a schematic transverse cross-section view of an isolated portion
of three
inclined plates defining two inclined channels, in which the plates are
substantially planar and in
which the profile of the inclined channels is comprised of a single peak and a
single trough.
DETAILED DESCRIPTION
The present invention is directed at an apparatus and a method for separating
a
flotation froth into a water component, a bitumen component, and in preferred
embodiments, an air
component.
In the following description of embodiments of the invention, the apparatus is
comprised of a separator, and the method is comprised of a method of using the
separator to
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CA 02633018 2008-05-30
separate the flotation froth into the air component, the water component and
the bitumen
component.
The invention may be used for separating a wide range of materials in addition
to
flotation froth. In the following description of specific embodiments of the
invention, however,
the apparatus and method are particularly intended for use in separating a
flotation froth which is
comprised of between 65 percent and 95 percent water by weight and between 4
percent and 25
percent bitumen by weight. In other words, the specific embodiments of the
invention are
particularly intended for use in separating a flotation froth which contains a
relatively low
concentration of bitumen and a relatively high concentration of water in
comparison with other
materials such as, for example, a primary bitumen froth obtained from an oil
sands primary
recovery process.
The flotation froth may also be comprised of a significant amount of a
flotation aid
such as air. For example, the flotation froth may be comprised of between 30
percent and 60
percent air by volume.
Referring to Figures 1-7, in some embodiments of the apparatus of the
invention,
the apparatus is comprised of a separator (20) for separating a flotation
froth (100) into an air
component (104), a water component (106) and a bitumen component (108).
Figures 1-5 are not
drawn to scale.
As depicted in Figure 1, for convenience, ease of fabrication and ease of
operation,
the separator (20) is comprised of a vessel (22) which contains and/or
comprises features of the
separator (20). Although the vessel (22) may be fabricated and configured to
he capable of being
pressurized and/or operated as a pressure vessel, the vessel (22) is
preferably fabricated and
configured to be operated at pressures which are not significantly higher or
lower than the ambient
pressure surrounding the separator (20).
The vessel (22) may be fabricated to have any suitable size and cross-section
shape.
As depicted in Figure 2 and Figure 6, the vessel (22) has a substantially
rectangular or square
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CA 02633018 2008-05-30
cross-section shape. Alternatively, in some embodiments the cross-section
shape of the vessel (22)
may be substantially round or may be some other shape.
The separator (20) is comprised of a plurality of substantially parallel
plates (24)
which are inclined at an inclination angle (26) relative to a horizontal
reference (28). The plates
(24) are arranged in a stacked manner, but are separated from each other by a
plate separation
distance (30), thereby providing inclined channels (32) between the plates
(24).
The plates (24) have a first end (34) and a second end (36). The first end
(34) of the
plates (24) is above the second end (36) of the plates (24).
As depicted in Figure 1, the plates (24) are contained within the vessel (22).
The
separation between the plates (24) and the position of the plates (24) within
the vessel (22) is
maintained by spacers (38) which interconnect the plates (24) and connect the
plates (24) with the
vessel (22).
The separator (20) is further comprised of a feed box (40), for containing the
flotation froth (100) which is introduced into the separator (20). The feed
box (40) may also
function as a surge tank in providing a surge volume to reduce the effects of
a fluctuating supply of
the flotation froth (100) to the separator (20).
The feed box (40) is adjacent to the first end (34) of the plates (24) and
extends
above the first end (34) of the plates (24). As depicted in Figure 1, the feed
box (40) is integrally
formed with or connected with the vessel (22).
The separator is further comprised of a discharge box (42), for collecting the
water
component and the bitumen component before they are discharged from the
separator (20).
The discharge box (42) is adjacent to the second end (36) of the plates (24)
and
extends below the second end (36) of the plates (24). As depicted in Figure 1,
the discharge box
(42) is integrally formed with or connected with the vessel (22).
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CA 02633018 2008-05-30
A flotation froth inlet (44) communicates with the first end (34) of the
plates (24).
As depicted in Figure 1, the flotation froth inlet (44) is associated with the
feed box (40) so that the
flotation froth inlet (44) communicates with the first end (34) of the plates
(24) via the feed box
(40). Optionally, a flotation froth inlet flow regulator (not shown) may be
provided, for facilitating
control of the introducing of the flotation froth (100) into the separator
(20). A source of flotation
froth (not shown) delivers the flotation froth (100) to the separator (20)
through the flotation froth
inlet (44).
In the embodiments depicted in Figures 1-7, an air component outlet (46)
communicates with the first end (34) of the plates (24). As depicted in Figure
1, the air component
outlet (46) is associated with the feed box (40) so that the air component
outlet (46) communicates
with the first end (34) of the plates (24) via the feed box (40). The air
component outlet (46) may
be omitted if the flotation froth (100) contains relatively small amounts of a
flotation aid such as
air or if for any reason it is not considered necessary or desirable to
separate the air component
(104) from the flotation froth (100).
As depicted in Figure 1, the air component outlet (46) is comprised of a vent
for
venting the air component (104) to the ambient atmosphere. Alternatively, the
air component
outlet (46) may be connected with a line (not shown) and/or other apparatus
(not shown) for
collecting, treating and/or compressing the air component (104).
A water component outlet (48) communicates with the second end (36) of the
plates
(24). As depicted in Figure 1, the water component outlet (48) is associated
with the discharge
box (42) so that the water component outlet (48) communicates with the second
end (36) of the
plates (24) via the discharge box (42). A water component outlet flow
regulator (50) facilitates
control of the discharging of the water component from the separator (20). In
the embodiment
depicted in Figure 1, the water component outlet flow regulator (50) is
comprised of a variable
speed pump or a variable output pump.
A bitumen component outlet (52) communicates with the second end (36) of the
plates (24). As depicted in Figure 1, the bitumen component outlet (52) is
associated with the
discharge box (42) so that the bitumen component outlet (52) communicates with
the second end
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CA 02633018 2008-05-30
(36) of the plates (24) via the discharge box (42). A bitumen component outlet
flow regulator (54)
facilitates control of the discharging of the bitumen component from the
separator (20). In the
embodiment depicted in Figure 1, the bitumen component outlet flow regulator
(54) is comprised
of a variable speed pump or a variable output pump.
A feed box level sensor (56) is associated with the feed box (40). The feed
box
level sensor (56) senses a level of the flotation froth (100) in the feed box
(40), which results in the
generation of data by the feed box level sensor (56). The nature of the data
generated by the feed
box level sensor (56) is dependent upon the nature of the feed box level
sensor (56), and may, as
non-limiting examples, be comprised of electric signals, mechanical signals or
optical signals.
A discharge box interface sensor (58) is associated with the discharge box
(42).
The discharge box interface sensor (58) senses an interface between the water
component and the
bitumen component in the discharge box (42), which results in the generation
of data by the
discharge box interface sensor (58). The nature of the data generated by the
discharge box
interface sensor (58) is dependent upon the nature of the discharge box
interface sensor (58), and
may, as non-limiting examples, be comprised of electric signals, mechanical
signals or optical
signals.
A controller (60) is operatively connected with the feed box level sensor (56)
and
with the discharge box interface sensor (58) so that the controller (60) can
receive the data
generated by the sensors (56,58).
The controller (60) is also operatively connected with the water component
outlet
flow regulator (50) and with the bitumen component outlet flow regulator (54).
The controller (60) is configured to receive the data from the feed box level
sensor
(56) and the discharge box interface sensor (58) and to use the data to
control the water component
outlet flow regulator (50) and the bitumen component outlet flow regulator
(54), as described in
detail below.
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CA 02633018 2008-05-30
The vessel (22) is supported on vessel supports (not shown). In the embodiment
depicted in Figure 1, the vessel (22) is configured so that the inclination
angle (26) of the plates
(24) is between 25 degrees and 35 degrees. In the embodiment depicted in
Figure 2, the plate
separation distance (30) is about 63 millimeters.
Referring to Figure 1, Figure 2 and Figure 6, the vessel (22) has a height
(62), a
width (64) and a length (66). In the embodiment depicted in Figure 1, Figure 2
and Figure 6, the
height (62) of the vessel (22) is 2 meters, the width (64) of the vessel (22)
is 2 meters, and the
length (66) of the vessel (22) is 20 meters.
In the embodiment depicted in Figure 1, Figure 2 and Figure 6, the vessel (22)
therefore contains about 30 plates (24).
Referring to Figure 1, the feed box (40) has a height (70), a width (72) and a
length
(74). In the embodiment depicted in Figure 1, the height (70) of the feed box
(40) is 3 meters, the
width (72) of the feed box (40) is 2 meters, and the length (74) of the feed
box (40) is 2 meters.
Referring to Figure 1, the discharge box (42) has a height (80), a width (82)
and a
length (84). In the embodiment depicted in Figure 1, the height (80) of the
discharge box (42) is 3
meters, the width (82) of the discharge box (42) is 2 meters, and the length
(84) of the discharge
box (42) is 2 meters.
Referring to Figures 2-7, each of the inclined channels (32) defines a profile
(90) in
a transverse direction (120), wherein the profile (90) is comprised of at
least one peak (92) and one
trough (94). Figures 2-6 depict different configurations of the plates (24)
which provide different
profiles (90), all of which comprise at least one peak (92) and one trough
(94).
In the embodiments depicted in Figures 2-5, each of the plates (24) is
substantially
horizontal in the transverse direction (120) and is comprised of a plurality
of discontinuities (122)
so that the profile (90) of the inclined channels (32) is comprised of a
series of alternating peaks
(92) and troughs (94).
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CA 02633018 2008-05-30
Referring to Figures 2 and 3, the profile (90) of the inclined channels (32)
is
sawtooth shaped (i.e., with alternating pointed peaks (92) and pointed troughs
(94)). Referring to
Figure 4, the profile (90) of the inclined channels (32) is corrugated (i.e.,
with alternating flat peaks
(92) and flat troughs (94)). Referring to Figure 5, the profile (90) of the
inclined channels (32) is
undulating (i.e., with alternating curved peaks (92) and curved troughs (94))
are depicted. Figures
3-5 represent non-limiting examples of possible profiles (90) of the inclined
channels (32) in
embodiments of the invention in which the profile (90) of the inclined
channels (32) is comprised
of a series of alternating peaks (92) and troughs (94).
As depicted in Figures 2-5, the distance between adjacent peaks (92) on a
particular
plate is between 20 centimeters and 30 centimeters. This distance is exemplary
only. The distance
between adjacent peaks (92) may be any distance which facilitates some
separation of the water
component (106) and the bitumen component (108) in the inclined channels (32).
In the embodiment depicted in Figures 6-7, each of the plates (24) is
substantially
planar and is tilted in the transverse direction (120) at a transverse
inclination angle (124) relative
to a transverse horizontal reference (125) so that the profile (90) of the
inclined channels (32) is
comprised of a single peak (92) and a single trough (94). The single peak (92)
is defined by a first
side (126) of the vessel (22) in the transverse direction (120) and the single
trough (94) is defined
by a second side (128) of the vessel (22) in the transverse direction (120).
As depicted in Figures 6-7, the transverse inclination angle (124) is about 10
degrees. This angle is exemplary only. The transverse inclination angle (124)
may be any distance
which facilitates some separation of the water component (106) and the bitumen
component (108)
in the inclined channels (32). For example, in some embodiments the transverse
inclination angle
(124) may be between 5 degrees and 60 degrees. In other embodiments the
transverse inclination
angle may be between 10 degrees and 20 degrees.
Referring to Figure 2 and Figure 6, baffles (96) are provided between the
uppermost
plate (24) and the vessel (24) and between the lowermost plate (24) and the
vessel (24), in order to
direct the flotation froth (100) so that it passes through the inclined
channels (32) which are
provided between pairs of adjacent plates (24).
27-
CA 02633018 2008-05-30
The method of the invention is now described in association with the
embodiments
of the apparatus of the invention which are depicted in Figures 1-7. In the
description of the
method that follows, the profile (90) of the inclined channels (32) may be any
profile (90),
including any of the profiles (90) depicted in Figures 2-7, which is comprised
of at least one peak
(92) and at least one trough (94) and which is capable of facilitating some
separation of the water
component (106) and the bitumen component (108) in the inclined channels (32).
The method of the invention separates the flotation froth (100) into the air
component (104), the water component (106) and the bitumen component (108).
In the following description of the method, the method is performed on a
continuous basis, with flotation froth (100) continuously being introduced
into the separator (20)
from a source (not shown) of the flotation froth (100). The method may also be
performed on a
batch basis, with flotation froth (100) intermittently being introduced into
the separator (20).
Referring to Figure 1, the flotation froth (100) is introduced into the
separator (20)
through the flotation froth inlet (44) so that the flotation froth (100) is
deposited into the feed box
(40).
The flotation froth (100) has a level (102) in the feed box (40). The
flotation froth
(100) may undergo some limited amount of separation while it is in the feed
box (40). For
example, a portion of the air component (104) of the flotation froth (100) may
become separated
from the flotation froth (100) in the feed box (40) and may be discharged from
the separator (20)
via the air component outlet (46).
The feed box (40) is adjacent to the first end (34) of the plates (24). As a
result, the
flotation froth (100) enters the inclined channels (32) at the first end (34)
of the plates (24) under
the influence of gravity.
Due to the configuration of the plates (24), the flotation froth (100) and/or
the
components (104,106,108) of the flotation froth (100) experience both
longitudinal movement and
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CA 02633018 2008-05-30
transverse movement within the inclined channels (32). The longitudinal
movement is along each
of the inclined channels (32) generally between the first end (34) of the
plates (24) and the second
end (36) of the plates (24). The transverse movement is in the transverse
direction (120) within
each of the inclined channels (32) between the plates (24) which define the
inclined channels (32).
As a result of these longitudinal and transverse movements, the flotation
froth (100) undergoes
some separation in the inclined channels (32) into the air component (104),
the water component
(106) and the bitumen component (108).
Referring to Figures 3-5 and Figure 7, the overall effect of the transverse
movement
is depicted. Specifically, the air component (104) and the bitumen component
(108) both migrate
upward within each of the inclined channels (32) to the peak (92) or peaks
(92) formed in the
upper plate (24) which defines the inclined channel (32). The water component
(106) migrates
downward within each of the inclined channels (32) to the trough (94) or
troughs (94) formed in
the lower plate (24) which defines the inclined channel (32).
Referring to Figure 1, the overall effect of the longitudinal movement is
depicted.
Specifically, due to its low density relative to the other components
(106,108) of the flotation froth
(100), the air component (104) moves along each of the inclined channels (32)
toward the first end
(34) of the plates (24), passes upward through the feed box (40), and is
discharged from the
separator (20) via the air component outlet (46). Meanwhile, the water
component (106) and the
bitumen component (108) move along each of the inclined channels (32) toward
the second end
(36) of the plates (24) and are collected in the discharge box (42).
In the embodiments of the separator (20) which are depicted in Figures 2-5.
the
water component (106) and the bitumen component (108) will both be collected
in the discharge
box (42) from a plurality of locations along the width (64) of the vessel
(22), corresponding to the
plurality of peaks (92) and troughs (94). In the embodiment of the separator
(20) which is depicted
in Figures 6-7, the bitumen component (108) will tend to be collected in the
discharge box (42)
from the first side (126) of the vessel (22) and the water component (106)
will tend to be collected
in the discharge box (42) from the second side (128) of the vessel. As a
result, the profile (90) of
the inclined channels (32) as depicted in Figures 6-7 may assist in
maintaining a separation
between the water component (106) and the bitumen component (108) in the
discharge box (42).
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CA 02633018 2008-05-30
The bitumen component (108) has a density which is slightly lower than the
density
of the water component (106). As a result, the water component (106) and the
bitumen component
(108) will tend to form two layers in the discharge box (42), with the bitumen
component (108)
"floating" on top of the water component (106). An interface (110) will define
a boundary
between the water component (106) and the bitumen component (108) in the
discharge box (42).
The bitumen component (108) also has a viscosity which is slightly higher than
the
viscosity of the water component (106). Due to the lower density and the
higher viscosity of the
bitumen component (108) relative to the water component (106), the
longitudinal movement of the
bitumen component (108) along the inclined channels (32) will tend to be
slower than the
longitudinal movement of the water component (106) along the inclined channels
(32), with the
result that the bitumen component (108) will take longer than the water
component (106) to move
to the discharge box (42).
The bitumen component (108) will therefore have a relatively longer residence
time
within the inclined channels (32) than the water component (106), providing
the bitumen
component (108) with relatively longer separation time within the inclined
channels (32) than the
water component (106).
The water component (106) and the bitumen component (108) may undergo further
separation in the discharge box (42), by which additional bitumen and/or air
is separated from the
water component (106) and additional water, solid mineral matter and/or air
are separated from the
bitumen component (108). Additional air which is separated from the water
component (106)
and/or the bitumen component (108) in the discharge box (42) may reenter the
inclined channels
(32) as the air component, move longitudinally along the inclined channels
(32) toward the first
end (34) of the plates (24), through the feed box (40), and be discharged from
the separator (20)
via the air component outlet (46).
The water component (106) is discharged from the separator (20) via the water
component outlet (48). The bitumen component (108) is discharged from the
separator (20) via
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CA 02633018 2008-05-30
the bitumen component outlet (52). The water component (106) and the bitumen
component (108)
are therefore separately discharged from the separator (20).
The level (102) of the flotation froth (100) in the feed box (40) is
maintained so that
it is above the first end (34) of the plates (24), thereby ensuring that the
flotation froth (100)
contained in the feed box (40) is in communication with the first end (34) of
the plates (24). The
level (102) of the flotation froth (100) is sensed by the feed box level
sensor (56), which results in
the generation of data by the feed box level sensor (56).
The interface (110) between the water component (106) and the bitumen
component (108) in the discharge box (42) is maintained so that it is above
the water component
outlet (48) and below the bitumen component outlet (52), thereby preserving
the separation of the
water component (106) and the bitumen component (108) when they are discharged
from the
separator (20). The interface (110) is sensed by the discharge box interface
sensor (58), which
results in the generation of data by the discharge box interface sensor (58).
The controller (60) receives the data from the feed box level sensor (56) and
the
discharge box interface sensor (58) and uses the data to control the water
component outlet flow
regulator (50) and the bitumen component outlet flow regulator (54). In
particular embodiments of
the invention, the controller (60) may receive electrical or electronic data
from the sensors (56,58)
and may control the flow regulators (50,54) mechanically, hydraulically,
pneumatically,
electrically, or in some other suitable manner.
By controlling the water component outlet flow regulator (50) and the bitumen
component outlet flow regulator (54), the level (102) of the flotation froth
(100) in the feed box
(40) can be maintained above the first end (34) of the plates (24) and the
interface (110) between
the water component (106) and the bitumen component (108) in the discharge box
(42) can be
maintained so that it is above the water component outlet (48) and below the
bitumen component
outlet (52).
The level (102) of the flotation froth (100) in the feed box (40) may be
maintained
by controlling the water component outlet flow regulator (50). By increasing
the rate of discharge
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CA 02633018 2008-05-30
of the water component (106) from the separator (20), the level (102) of the
flotation froth (100) in
the feed box (40) can be lowered. By decreasing the rate of discharge of the
water component
(106) from the separator (20), the level (102) of the flotation froth (100) in
the feed box (40) can
be raised.
The interface (110) between the water component (106) and the bitumen
component (108) in the discharge box (42) may be maintained by controlling the
bitumen
component outlet flow regulator (54). By increasing the rate of discharge of
the bitumen
component (108) from the separator (20), the interface (110) in the discharge
box (42) can be
raised. By decreasing the rate of discharge of the bitumen component (108)
from the separator
(20), the interface (110) in the discharge box (42) can be lowered.
The water component (106) which is discharged from the separator (20) may be
disposed of in some manner, such as being disposed of as tailings or waste
water. If the water
component (106) contains significant amounts of bitumen, the water component
(106) may be
subjected to an oil sands secondary recovery process in order to recover
bitumen therefrom.
The bitumen component (108) which is discharged from the separator (20) may
have a quality which is sufficiently high so that the bitumen component (108)
is suitable as a
bitumen product, in which case the bitumen component (108) may be combined
with one or more
bitumen products obtained from other oil sands recovery processes, such as an
oil sands primary
recovery process. Alternatively, if the bitumen component (108) has a quality
which is not
sufficiently high so that the bitumen component (108) is suitable as a bitumen
product, the bitumen
component (108) may be recycled for further processing to another oil sands
recovery process,
such as an oil sands primary recovery process.
Based upon numerical modelling of the invention, it is believed that the water
component (106) which is produced by the method of the invention may be
expected to be
comprised of between 1 percent and 3 percent bitumen by weight, between 5
percent and 20
percent solid mineral matter by weight, and between 65 percent and 90 percent
water by weight.
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Similarly, based upon numerical modelling of the invention as described in the
Examples which follow, it is believed that the bitumen component (108) may be
expected to be
comprised of between 25 percent and 50 percent bitumen by weight, between 8
percent and 25
percent solid mineral matter by weight, between 25 percent and 65 percent
water by weight, and
less than 20 percent or perhaps even less than 10 percent air by volume.
Examples
Two Examples of the performance of the method of the invention, based upon
numerical modelling, are provided.
In both Examples, the separator (20) is comprised of a vessel, a feed box (40)
and a
discharge box (42). The vessel (22) has a height (62) of 2 meters, a width
(64) of 2 meters and a
length (66) of 20 meters. The feed box (40) has a height (70) of 3 meters, a
width (72) of 2 meters
and a length (74) of 2 meters. The discharge box (42) has a height (80) of 3
meters, a width (82)
of 2 meters and a length (84) of 2 meters.
In both Examples, the plates (24) are contained within the vessel (22). The
thickness of the plates (24) is about 3 millimeters and the plate separation
distance (30) is 63
millimeters. The distance between centerlines of adjacent plates (24) is
therefore about 66
millimeters so that the separator (20) includes about 30 plates (24). The
inclined channels (32)
have a corrugated profile (90) similar to the profile (90) depicted in Figure
4, with alternating flat
peaks (92) and flat troughs (94). The distance between adjacent peaks (92) on
a particular plate
(24) is 30 centimeters. The inclination angle (26) of the plates is 25
degrees.
In Example 1, the flotation froth (100) is a "high grade" flotation froth
(100)
obtained from a middlings stream produced by a hot water oil sands recovery
process. The high
grade flotation froth (100) is comprised of 20 percent bitumen by weight, 10
percent solid mineral
matter by weight, and 70 percent water by weight.
In Example 1, the separator (20) is operated to provide a mean residence time
of the
flotation froth (100) in the separator (20) of 12.8 minutes.
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CA 02633018 2008-05-30
In Example 2, the flotation froth (100) is a "low grade" flotation froth (100)
obtained from a middlings stream produced by a hot water oil sands recovery
process. The low
grade flotation froth (100) is comprised of 10 percent bitumen by weight, 12
percent solid mineral
matter by weight, and 78 percent water by weight.
In Example 2, the separator (20) is operated to provide a mean residence time
of the
flotation froth (100) in the separator (20) of 6.5 minutes.
Model material balances for Example I and Example 2 are provided at the end of
this Description.
The apparatus and the method of the invention therefore provide for the
separation
of the flotation froth (100) into the water component (106), the bitumen
component (108), and
optionally the air component (104). The bitumen component (108) contains a
significantly higher
concentration of bitumen and may contain a significantly lower amount of air
than the flotation
froth (100). The increased concentration of bitumen in the bitumen component
(108) may increase
the potential value of the bitumen component (108) relative to the flotation
froth (100), and the
reduced amount of air in the bitumen component (108) may reduce potential
handling and/or
transport difficulties relative to the flotation froth (100).
In this document, the word "comprising" is used in its non-limiting sense to
mean
that items following the word are included, but items not specifically
mentioned are not excluded.
A reference to an element by the indefinite article "a" does not exclude the
possibility that more
than one of the elements is present, unless the context clearly requires that
there be one and only
one of the elements.
-34-
CA 02633018 2008-05-30
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