Note: Descriptions are shown in the official language in which they were submitted.
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Enhanced Bitumen Flotation
Field of the invention
[01] The present invention relates to a method and apparatus for recovering
bitumen from a
feed stream having solids, water and bitumen. More particularly, it relates to
the use of a
separating vessel having mounted thereon a downpipe assembly comprising at
least one
downpipe and a nozzle in fluid communication with each downpipe for aerating a
stream of
middlings withdrawn from the separating vessel.
Background of the invention
[02] Oil sand, such as is mined in the Fort McMurray region of Alberta,
generally comprises
water-wet sand grains held together by a matrix of viscous bitumen. It lends
itself to liberation
of the sand grains from the bitumen, preferably by slurrying the oil sand in
hot process water,
allowing the bitumen to move to the aqueous phase.
[03] For many years, the bitumen in the McMurray sand has been commercially
removed
from oil sand using what is commonly referred to in the industry as the "hot
water process". In
general terms, the hot water process involves the following steps:
= dry mining the oil sand at a mine site that can be kilometres from an
extraction plant;
= conveying the as-mined oil sand on conveyer belts to the extraction plant;
= feeding the oil sand into a rotating tumbler where it is mixed for a
prescribed retention
time (generally in the range of 2 to 4 minutes) with hot water (approximately
80-90 C),
steam, caustic (e.g., sodium hydroxide) and naturally entrained air to yield a
slurry that
has a temperature typically around 80 C. The bitumen matrix is heated and
becomes less
viscous. Chunks of oil sand are ablated or disintegrated. The released sand
grains and
separated bitumen flecks are dispersed in the water. To some extent bitumen
flecks
coalesce and grow in size. They may contact air bubbles and coat them to
become
aerated bitumen. The term used to describe this overall process in the tumbler
is
"conditioning"; and
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= diluting the slurry so produced with additional hot water to produce a
diluted slurry
having a temperature of about 65 C to about 80 C. The diluted slurry is
introduced into a
large, open-topped, conical-bottomed, cylindrical vessel termed a primary
separation
vessel (PSV) where the more buoyant aerated bitumen rises to the surface and
forms a
froth layer. This froth layer overflows the top lip of the PSV and is received
in a launder
extending around the PSV's rim. The product is commonly called "primary froth"
and
typically has a temperature of about 65 C to about 75 C.
[04] Throughout the years, the hot water process has been modified to be more
energy
efficient by reducing the process temperature and replacing short-duration,
high-temperature
conditioning in a tumbler with longer-duration, lower-temperature conditioning
in a
hydrotransport pipeline. A "warm slurry extraction process" was developed in
the early 1990s
and is disclosed in Canadian Patent No. 2,015,784. In the late 1990s, a cold
dense slurrying
process for extracting bitumen from oil sand was developed, which is disclosed
in Canadian
patent No. 2,217,623. This process is commonly referred to as the "low energy
extraction
process" or the "LEE process".
[05] All of the above extraction processes use a PSV for receiving diluted oil
sand slurry and
separating the aerated or floating bitumen from the sand. The typical
residence time in the PSV
is approximately 45 minutes. During this time, the sand sinks and is
concentrated in the bottom
section of the PSV where it is removed as tailings underflow (also referred to
herein as "PSV
tailings"). Some valuable bitumen is lost to this underflow. Further, a
portion of the non-aerated
(i.e., non-floating) bitumen remains in the watery mid-section of the PSV,
together with
dispersed fine solids. This watery suspension is referred to in the industry
as "middlings" and in
the present invention will also be referred to as "PSV middlings".
[06] To improve overall bitumen recovery, it is important to capture both the
floating and non-
floating bitumen that still remains in the middlings and tailings underflow.
One way for
recovering bitumen from PSV tailings and middlings is described in Canadian
Patent No.
1,248,476 and U.S. Patent No. 4,545,892. In these patents, the PSV tailings
and middlings are
combined and introduced into a second separation vessel referred to as the
tailings oil recovery
vessel ("TORN"). Briefly stated, the incoming feed to the vessel is deflected
and spread out
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laterally and contacted from below by an upwelling stream of aerated and
recycled TORY
middlings. The air bubbles in the recycled TORV middlings contact and aerate
previously non-
buoyant bitumen in the feed to produce "secondary" bitumen froth.
[07] More particularly, a plenum assembly is positioned inside the TORY,
centrally of the
chamber of the TORY, in the body of the TORY middlings. The plenum assembly
comprises a
plurality of eductor/aerator devices, each eductor/aerator device comprising a
nozzle and a
venturi tube, the nozzle being positioned close to but gapped from the venturi
tube. Each
eductor/aerator device extends outwardly from the plenum assembly lower wall,
being connected
to the lower wall by the venturi tube. Finally, each nozzle is circumscribed
by a tubular sparger
mounted thereon.
[08] The recycled TORV middlings are upwardly fed at a high velocity into the
nozzles of the
eductor/aerator assemblies in order to entrain additional middlings present in
the TORY.
Pressurized air is fed to the tubular sparger to aerate the recycled middlings
feed. The aerated
middlings exit the nozzle and are injected into the inlet of the venturi tube.
The motive jet of
recycled middlings induces a flow of non-aerated middlings from the TORY
chamber through
the gap formed between the nozzle and the venturi tube. The aerated middlings
first collect in
the plenum chamber and are then discharged outwardly, slightly upwardly, and
generally radially
from the plenum chamber through slot-like outlets.
[09] In operation, however, there were several drawbacks to using the above-
described
plenum assembly. For example, the eductor/aerator devices would routinely
become plugged
with or damaged by the solids present in the recycled middlings. Further, the
recycled middlings
had to be fed at relatively high motive velocities in order to generate
additional entrainment of
middlings, which further contributed to the erosion damage to the
eductor/aerator devices.
Finally, because the plenum assembly was situated inside the TORY, the entire
TORY operation
had to be shut down and the plenum assembly removed whenever maintenance of
the plenum
assembly was required. The TORY would have to be drained to enable access to
the normally
submerged assembly, resulting in labor and repair costs as well as lost
production.
[10] The present invention addresses some of the problems associated with the
plenum
assembly by providing a gravity separation vessel having mounted thereto a
downpipe assembly
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comprising at least one downpipe having a nozzle for aerating recycled
middlings, which
downpipe assembly does not need to be internally mounted. Thus, the downpipe
assembly is
easily accessible for maintenance without having to shut down the entire
vessel operation.
Summary of the invention
[11] In accordance with an aspect of the invention, a method for continuously
recovering
bitumen as froth from a feed stream having solids, water and bitumen is
presented, including:
= delivering the feed stream into a separating vessel through a feedwell and
allowing the
feed stream to separate into an upper bitumen-rich zone, a middlings zone and
a lower
concentrated solids zone;
= providing a downpipe assembly comprising at least one downpipe having an
upper end
and an open lower end, said downpipe assembly mounted to the separation vessel
such
that each downpipe extends substantially vertically into the separation vessel
and the
open lower end of each downpipe extends below the bitumen-rich zone;
= removing a stream of middlings from the middlings zone of the separation
vessel and
introducing the middlings stream into the upper end of the downpipe by means
of a
nozzle positioned at or near the upper end of each downpipe to form a jet of
middlings;
= introducing air into the middlings stream to produce aerated middlings and
allowing the
aerated middlings to issue from the open lower end of each downpipe below the
bitumen-
rich froth zone of the separation vessel; and
= continuously recovering the bitumen froth from the upper bitumen-rich zone
and
withdrawing the solids from the lower concentrated solids zone in the
separation vessel.
[12] The term "nozzle" in the present invention includes any device having a
contracting,
tapering tube or vent, an orifice plate, or the like, which can be used to
accelerate the flow of a
liquid.
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[13] In one embodiment, air is introduced into the middlings stream through an
opening at or
near the upper end of the downpipe. In another embodiment, air is introduced
into the middlings
stream prior to introducing the middlings into the nozzle.
[14] The present method targets both the floating bitumen (i.e., aerated
bitumen) and the non-
floating bitumen present in a feed stream. Without being bound to theory, it
would be expected
that all floating bitumen present in a feed stream would be recovered in a
separating vessel.
However, this does not appear to be the case, likely due to mixing in the
vessel and/or
insufficient residence time. Thus, some of the floating bitumen still reports
to the middlings
zone. Further, a significant amount of the bitumen in the feed stream may be
present as non-
floating bitumen, likely due to the bitumen droplets being contaminated with
solids or that the
droplets are too small to promote aeration and flotation. Hence, non-floating
bitumen may also
be present in the middlings zone and in the lower solids layer. This non-
floating bitumen
requires more substantial shearing/conditioning and/or applied aeration to
promote some portion
of it to be floatable.
[15] By way of example, it is estimated that somewhere between about 50 to
about 80 percent
of the bitumen remaining in the combined PSV middlings and PSV tailings is in
the form of non-
floating bitumen. Thus, successful capture of even a portion of this non-
floating bitumen can
significantly increase the overall bitumen recoveries from oil sand slurry.
Hence, the present
invention is directed towards increasing the recovery of non-floating bitumen
present in a feed
stream having solids, water and bitumen.
[16] In one embodiment of the present invention, the separating vessel is a
primary separation
vessel (PSV), as known in the art, and the feed stream is diluted oil sand
slurry. The downpipe
assembly of the present invention is mounted to the PSV and the PSV middlings
are
continuously recycled back to the downpipe assembly to aerate a portion of the
non-floating
bitumen present therein. The aerated PSV middlings are thus introduced back
into the PSV
where the aerated bitumen will now have an opportunity to be recovered as
primary froth. The
continuous recycling of the PSV middlings also provides the floating bitumen
present in the PSV
middlings another opportunity to report to the bitumen-rich zone.
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[17] In another embodiment, the separating vessel of the present invention is
a secondary
separation vessel, for example, a tailings oil recovery vessel (TORN), as
known in the art, and
the feed stream is PSV middlings or combined PSV middlings and PSV tailings.
In this
embodiment, the downpipe assembly of the present invention is mounted to the
TORY and the
TORY middlings are continuously recycled back to the downpipe assembly, where
a portion of
the non-floating bitumen is aerated and then introduced back into the TORY.
The aerated
bitumen will now have an opportunity to be recovered as secondary or TORY
froth. The
continuous recycling of the TORV middlings also gives the floating bitumen
present in the
TORV middlings another opportunity to report to the bitumen froth layer.
[18] In accordance with another aspect of the invention, an apparatus for
continuously
recovering bitumen as froth from a feed stream having solids, water and
bitumen is presented,
having:
= a separating vessel having a feedwell for receiving the feed stream, the
separating vessel
operative for separating the feed stream into an upper bitumen-rich zone, a
middlings
zone and a lower concentrated solids zone;
= a downpipe assembly having at least one downpipe with an upper end and an
open lower
end, said downpipe assembly mounted to the separation vessel such that each
downpipe
extends substantially vertically into the separation vessel and the open lower
end of each
downpipe extends below the bitumen-rich zone;
= a nozzle positioned at or near the upper end of each downpipe and in fluid
communication with the downpipe;
= means for removing a stream of middlings from the middlings zone of the
separating and
introducing the stream of middlings into the nozzle; and
= an air supply means for introducing air into the stream of middlings and
producing
aerated middlings.
[19] The downpipe assembly of the present invention can be readily maintained
without
interfering with the vessel operation, as it does not have to be mounted
internally like the prior
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art plenum assembly. Further, each individual downpipe can ' be separately
maintained or
replaced without interfering with the operation of the other downpipes.
Existing separation
vessels can be easily retrofitted with a downpipe assembly of the present
invention in order to
practice the invention.
[20] In addition, lower nozzle velocities are needed in the present invention.
In the prior art
plenum assembly, high nozzle velocities were needed in order to produce
entrainment of
additional middlings slurry into the venturis of the eductor/aerator devices.
The recycled
middlings flow through the nozzles was only about 3,000 USGPM. Thus, it was
desirable to
entrain several times that amount into the venturis for improved bitumen
recoveries. In the
present invention, however, entrainment of additional middlings is not
necessary. The use of
downwardly fed downpipes allows for direct pumping of higher volumes of
recycled middlings
through the nozzles, for example, up to about 14,000 USGPM. Hence, the
recycled middlings
can be fed at much lower velocities that the velocities needed when using the
prior art
eductor/aerator assembly. Further, because the recycled middlings are fed
downwardly through
the downpipe, there is a lower air requirement needed to aerate the recycled
middlings.
[21] Lowering the feed velocity allows one to use nozzles having larger
diameter openings or
orifices. For example, in the previous prior art plenum assembly, the nozzles
used had to have
nozzle opening of about 3 inches in diameter to maintain a high enough
velocity of about 25
meters/second. Since some of the largest solids present in the middlings could
be close to 3
inches in diameter, the nozzles would regularly plug. In the present
invention, however, the
velocity needed is much lower and can be as low as about 5 to 10
meters/second, or lower. Thus,
nozzles can be used in the present invention that have openings as large as 6
inches in diameter,
or higher. Thus, the reduced velocity and larger diameter openings in the
nozzles of the present
invention ultimately leads to less plugging of the nozzles and less wear.
Brief description of the drawings
[22] The features and advantages of the invention will become more apparent
from the
following detailed description of the embodiment with reference to the
attached diagrams
wherein:
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[23] Figure 1 is a schematic flowsheet showing one embodiment of the invention
where the
separating vessel used for recovering non-floating bitumen is a TORV and the
feed stream is a
combination of PSV middlings and PSV tailings.
[24] Figure 2 is a schematic flowsheet showing one embodiment of the invention
where the
separating vessel used for recovering non-floating bitumen is a TORY and the
feed stream is
PSV tailings. In this embodiment, the PSV middlings are combined with the TORY
middlings
and aerated in the TORV downpipe assembly.
[25] Figure 3 is a schematic flowsheet showing one embodiment of the invention
where the
separating vessel used for recovering non-floating bitumen is a PSV and the
feed stream is
diluted oil sand slurry.
[26] Figure 4 is a perspective of a downpipe assembly comprising a plurality
of downpipes
mounted to a separation vessel that can be used to practice the present
invention.
[27] Figure 5 is a cross-section of a downpipe that can be used to practice
the present
invention.
[28] It will be noted that in the attached diagrams like features bear similar
labels.
Detailed description of the embodiments
[29] The detailed description set forth below in connection with the appended
drawings is
intended as a description of various embodiments of the present invention and
is not intended to
represent the only embodiments contemplated by the inventors. The detailed
description
includes specific details for the purpose of providing a comprehensive
understanding of the
present invention. However, it will be apparent to those skilled in the art
that the present
invention may be practiced without these specific details.
[30] An embodiment of the invention is shown in Figure 1. In this embodiment,
the feed
stream is combined middlings and tailings obtained from a primary separation
vessel (PSV) and
the separating vessel comprising a downpipe assembly of the present invention
is a tailings oil
recovery vessel (TORN).
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[31] With reference to Figure 1, diluted oil sand slurry is introduced into
PSV 10 via feed line
12, where the diluted slurry is temporarily retained under quiescent
conditions to produce an
overflowing primary bitumen froth stream ("PSV froth"), a middlings stream
recovered from the
midsection of the PSV 10 ("PSV middlings"), and an underflow sand tailings
stream ("PSV
tailings"). In a preferred embodiment, an underwash of warm water is
introduced via line 14
directly underneath the layer of primary bitumen froth.
[32] Primary bitumen froth overflows into launder 16 and is collected for
further upgrading.
The PSV middlings and the PSV tailings are both pumped through withdrawal
lines 18 and 20,
respectively, and are combined into a single feed stream in feed line 22.
[33] As previously mentioned, both the PSV middlings and the PSV tailings
comprise a
significant amount of bitumen. Typically, the portion of bitumen that is not
recovered as
primary bitumen froth is between about 2% to about 10% of the total bitumen
present in the
diluted oil sand slurry. A large portion of the remaining bitumen is present
in the form of non-
floating bitumen.
[34] The feed stream of combined PSV middlings and PSV tailings is introduced
into TORV
24 via feed line 26, which is connected to feedwell 28. It is understood that
the PSV middlings
and PSV tailings could also be fed to the feedwell via separate feed lines as
shown in Figure 4.
The feed stream is temporarily retained in TORV 24 to produce an overflowing
secondary
bitumen froth stream ("TORN froth"), a middlings stream ("TORN middlings") and
an
underflow sand tailings stream ("TORN tailings"). A significant portion of the
non-floating
bitumen reports to the TORY middlings. Preferably, feedwell 28 extends into
the TORY
middlings layer, where the feed stream is introduced. However, it is
understood that the feed
stream can be introduced into the TORV 24 by other means known in the art.
[35] The TORY middlings, which contain both the floating and non-floating
bitumen, are
continuously removed via withdrawal line 30 and further aerated by means of
downpipe
assembly 31. Downpipe assembly 31 comprises at least one downpipe 32 and each
downpipe 32
has a flow nozzle 34 located at or near the upper end 36 of downpipe 32. In
this embodiment,
flow nozzle 34 comprises a nozzle tube and an orifice plate. It is understood
that a variety of
different types of nozzles can be used to produce the middlings jet. In this
embodiment, air is
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injected into the middlings stream prior to the middlings entering nozzle 34.
In another
embodiment, downpipe 32 further comprises at least one air inlet (as shown in
Figure 5) for
entraining air. In yet a further embodiment, the upper end of the downpipe is
not completely
sealed around the nozzle, thereby allowing air to be drawn therethrough. Lower
end 38 of
downpipe 32 is open to TORV 24 and the aerated TORV middlings are introduced
into the
TORV middlings layer.
[36] Overflowing TORV froth is collected in launder 40 and may be pumped back
to PSV 10
via line 42. The TORV froth is typically first mixed with diluted oil sand
slurry before being
introduced into PSV 10. In the alternative, the TORV froth can be combined
with PSV froth for
further upgrading. TORV tailings are also continuously removed via line 44 to
be either further
treated or disposed in tailings disposal sites.
[37] Figure 2 shows another embodiment of the present invention. In this
embodiment, the
feed stream to the TORV 24 via feedwell 28 is PSV tailings only. The PSV
middlings are
removed via withdrawal line 118 and combined with TORV middlings and the
combined PSV
and TORV middlings are then fed to downpipe assembly 31 for aeration.
[38] Figure 3 shows another embodiment of the present invention. In this
embodiment, the
settling vessel is PSV 310, which has been retrofitted with downpipe assembly
331. Diluted oil
sand slurry is fed into PSV 310 via feedwell 328. The diluted slurry is
temporarily retained
under quiescent conditions to produce an overflowing primary bitumen froth
stream ("PSV
Froth"), a middlings stream recovered from the midsection of the PSV 310 ("PSV
middlings"),
and an underflow sand tailings stream ("PSV tailings").
[39] PSV froth overflows into launder 316 and is collected for further
upgrading. PSV
tailings are continuously removed for further treatment or disposal in
suitable tailings disposal
sites. The PSV middlings, however, are continuously removed via withdrawal
line 318 and
recycled back to downpipe assembly 331. Downpipe assembly 331 comprises nozzle
334 and
downpipe 332. The upper end 336 of downpipe 332 further comprises air inlet
333 for supplying
air 335 into downpipe 332. The PSV middlings flow through the nozzle 334
causing a jet 337 to
issue in a downward path into downpipe 332. The jet 337 of middlings issuing
from the nozzle
334 sheers and then freely entrains air through the open ended air inlet 333.
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[40] The jet 337 and air entrained with it are forced together in the limited
volume of the
downpipe 332 which creates a mixing zone 339. The aerated PSV middlings exit
from the open
lower end 338 into PSV 310.
[41] Figure 4 shows one embodiment of a separating vessel equipped with a
downpipe
assembly that can be used to practice the present invention. Settling vessel
450 comprises
launder 416 for collecting the overflowing bitumen froth, middlings outlet 454
for removing
middlings, and tailings outlet (not shown) for removing the solids that settle
to the bottom of the
settling vessel. Middlings that are removed via middlings outlet 454 and are
recycled via feed
line 455, which splits into smaller feed lines for feeding each individual
downpipe 432 of
downpipe assembly 431. A slurry distributor (not shown) could also be used to
distribute the
middlings to the downpipes. Middlings are introduced into nozzles 434 to
produce a jet of
middlings in each downpipe 432. Air is naturally entrained through air inlets
434 and into each
downpipe where the high sheer rate of the plunging jet results in the
entrained layer of air being
broken down into a multitude of small air bubbles, typically of about 500 tm
diameter, which
are carried down the downpipe 432.
[42] Figure 5 is a cross-section of one embodiment of a downpipe useful in the
present
invention. Downpipe 432 comprises an upper end 436, which end is in fluid
communication
with nozzle 434. Nozzle 434 ends in orifice 446 for accelerating the feed
stream and producing a
feed stream jet 437 in downpipe 432. The feed stream jet 437 entrains air 435
from air inlet 433
and shears the air into a multitude of smaller air bubbles. The jet 437 and
entrained air are
forced together in the limited volume of the downpipe 432 to create mixing
zone 439.
[43] Examples
[44] The present invention was tested using a separating vessel similar to the
TORV that is
currently being used in the applicant's oil sands operations as a secondary
gravity settling tank.
Three TORV operating conditions were tested:
(1) TORY operating as a simple gravity settler;
(2) direct air injection into the TORV feed stream; and
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(3) using a downpipe assembly mounted to the TORV for aerating TORV middlings.
[45] Preparation of the Feed Stream
[46] Two grades of oil sand were tested, a low-grade ore (9.6% bitumen, 21%
fines) and a
poor processing ore (8.9% bitumen, 24% fines). Generally, an ore such as the
poor processing
ore having such low bitumen (8.9%) and high fines (24%) would not be used
commercially
without blending it with higher grade ores. However, if recovery of bitumen
can be sufficiently
increased practicing the present invention, processing of such poor grade oil
sand may be more
economically viable.
[47] Each ore sample was first mixed with hot water and NaOH in a tumbler with
a zero
discharge weir height for minimum residence time. The oversize rejects were
removed using a
trommel screen (1/4 inch woven wire mesh) at the discharge end of the tumbler.
The oil sand
slurry passed through the screens into a mixing tank, and was pumped into a
100 mm diameter
pipeline loop for oil sand slurry conditioning. The conditioned slurry was
removed through a
slipstream off the pipeline loop.
[48] Flood water was added to the conditioned slurry as it was fed to a
primary separation
vessel (PSV), but no air was added to the slurry. Froth underwash water was
introduced to the
PSV in the vicinity below the froth layer. PSV middlings were withdrawn at 300
g/s and the
PSV tailings flow rate controlled the froth interface level. The PSV middlings
and PSV tailings
were combined and used as the TORV feed stream. About 90% of the total bitumen
reported to
the primary froth layer. Thus, about 10% bitumen still remained in the TORV
feed stream. Of
the bitumen present in the TORV feed stream, it was estimated that about 41%
of the bitumen
was floating (i.e., aerated) bitumen.
[49] TORV operating as a simple gravity settler
[50] The TORV was operated as a simple tank to provide additional passive
bitumen recovery.
PSV middlings and tailings were used as feed and the TORV middlings were
discharged at a rate
of 200 g/s. The TORV tailings removal rate controlled the bitumen froth
interface level. The %
bitumen recovered in the TORV was measured.
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[51] TORV with direct air addition to the feed stream
[52] Air was added to the PSV middlings and the PSV tailings as separate
streams using
perforated inline pipe sections for the air addition. The two aerated streams
were then combined
prior to feeding the combined stream to the feedwell of the TORY. The TORV
middlings were
discharged at a rate of 200 g/s. The TORY tailings removal rate controlled the
bitumen froth
interface level. The % bitumen recovered in the TORV was measured.
[53] TORV with downpipe assembly
[54] In this instance, the TORV was further equipped with a downpipe assembly
of the
present invention. The feed stream was introduced into the TORY via the
feedwell and the
TORV middlings were removed and fed to the downpipe assembly to provide the
TORV
middlings with further aeration. The TORY tailings removal rate controlled the
bitumen froth
interface level and the % bitumen recovered in the TORY was measured.
[55] Table 1 shows the % recovery of bitumen from TORV feed stream using low-
grade ore
under the above three conditions. In this example, the PSV recovery of bitumen
was about 90%
and it was estimated that 41% of the bitumen in the TORY feed stream was in
the form of
floating bitumen.
Table 1
TORV Operation Simple Tank Air Injection TORV + Downpipe
Assembly
TORY Recovery 43% < 43% 56%
Increment in TORY Recovery + 13%
Compared to Simple Tank
Increment in Extraction Recovery + 1%
Compared to the Simple Tank
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[56] The incremental increase in overall bitumen recovery of 1% would amount
to significant
commercial value. In current operations, this would amount to an additional
1.5 million barrels
of bitumen per year.
[57] Table 2 shows the % recovery of bitumen from TORV feed stream using poor
processing
ore under the above three conditions. In this example, the PSV recovery of
bitumen was only
about 30% and it was estimated that only 14% of the bitumen in the TORV feed
stream was in
the form of floating bitumen.
Table 2
TORV Operation Simple Tank Air Injection TORV + Downpipe
Assembly
TORY Recovery 15% 27% 51%
Increment in TORY Recovery + 36%
Compared to Simple Tank
Increment in Extraction Recovery + 15%
Compared to the Simple Tank
[58] It can be seen from this example that use of the present invention
resulted in a recovery
of almost half of the non-floating bitumen present in the feed stream. The
incremental increase
in overall bitumen of 15% indicates that poor processing ore may be a viable
source of bitumen
when using the present invention for secondary bitumen recovery.
[59] The previous description of the disclosed embodiments is provided to
enable any person
skilled in the art to make or use the present invention. Various modifications
to those
embodiments will be readily apparent to those skilled in the art, and the
generic principles
defined herein may be applied to other embodiments without departing from the
spirit or scope
of the invention.
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CA 02577743 2007-02-09
[60] Thus, the present invention is not intended to be limited to the
embodiments shown
herein, but is to be accorded the full scope consistent with the claims,
wherein reference to an
element in the singular, such as by use of the article "a" or "an" is not
intended to mean "one and
only one" unless specifically so stated, but rather "one or more". All
structural and functional
equivalents to the elements of the various embodiments described throughout
the disclosure that
are known or later come to be known to those of ordinary skill in the art are
intended to be
encompassed by the elements of the claims. Moreover, nothing disclosed herein
is intended to
be dedicated to the public regardless of whether such disclosure is explicitly
recited in the
claims.
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