Note: Descriptions are shown in the official language in which they were submitted.
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DOCKET NO.: NS-506
INTEGRATED PROCESS FOR REDUCING SOLIDS FROM THE PRODUCT OF
SOLVENT EXTRACTION OF OIL SANDS BITUMEN
FIELD OF THE INVENTION
The present invention relates generally to methods of reducing solids content
in
high-solids diluted bitumen produced by an existing solvent extraction process
of mined
oil sand.
BACKGROUND OF THE INVENTION
Oil sand deposits such as those found in the Athabasca Region of Alberta,
Canada, generally comprise water-wet sand grains held together by a matrix of
viscous
heavy oil or bitumen. Bitumen is a complex and viscous mixture of large or
heavy
hydrocarbon molecules which contain a significant amount of sulfur, nitrogen
and
oxygen. Oil sands processing involves either Clark hot water extraction or
solvent
extraction to produce diluted bitumen which is further processed to produce
synthetic
crude oil and other valuable commodities. Clark hot water extraction
technology or its
variants require large amounts of water and generate a great quantity of wet
tailings.
Part of the wet tailings becomes mature fine tailings which contain
approximately 30%
fine solids and are a great challenge for tailings treatment. In addition,
certain problem
oil sands, often having high fines content, yield low bitumen recoveries in
the water-
based extraction process. This leads to economic losses and environmental
issues with
bitumen in wet tailings.
In contrast, solvent extraction of bitumen from mined oil sands uses little or
no
water, generates no wet tailings, and can achieve higher bitumen recovery than
the
exiting water-based extraction. Solvent extraction usually produces diluted
bitumen
product containing less than about 0.5 wt% water without any additional
treatment step
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such as centrifugation or deasphalting. Solvent extraction is thus potentially
more
robust and more environmentally friendly than water-based extraction.
Solvent extraction is conducted using either a single solvent or mixture of
solvents. One process uses paraffinic solvents and rejects a significant
amount of
asphaltene (see for example, Canadian Patent Application No. 2,715,301 and
Canadian
Patent Application No. 2,724,806). This process yields a low-solids product
similar to a
paraffinic froth treatment product, which contains less than about 0.1 wt%
water and
solids and is pipelinable and marketable. The diluted bitumen product is
produced with
low solids content through a fines capture process with asphaltene
precipitation.
Product of less than about 0.04 wt% (400 mg/kg) solids on dry bitumen basis
with
significant deasphalting has been reported. However, this process does not
recycle the
asphaltene-rich tails. Product of less than about 0.1 wt% (1000 mg/kg) solids
on dry
bitumen basis with significant deasphalting has also been reported. However,
mixing
the asphaltene-rich tails with the oil sand-solvent slurry causes the release
of the
captured fines back into the hydrocarbon product, defeating the purpose of
product
cleanup by deasphalting. The combined bitumen (maltene and asphaltene)
recovery for
solvent extraction processes with significant asphaltene rejection is
estimated below
about 88%, considering about 6% loss of bitumen in the extraction itself.
Another solvent extraction process uses aromatic and paraffinic solvents, and
rejects little asphaltene (see for example, Canadian Patent Application No.
2,761,555
and Canadian Patent Application No. 2,751,719). Bitumen recovery greater than
about
95% can be achieved. However, this process normally produces a high-solids
product
similar to a naphtha froth treatment product, which is not marketable without
upgrading.
The diluted bitumen product typically contains about 0.2-0.5 wt% of solids on
dilbit basis
and about 0.4-1 wt% on dry bitumen basis. The solids are almost exclusively
fines
which are difficult to remove by settling or centrifugation. Bitumen may be
lost in the
centrifuge tails. The product must be locally upgraded by coking to be
pipelinable and
marketable.
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Accordingly, there is a need for a method of producing low-solids marketable
bitumen at a reasonably high bitumen recovery.
SUMMARY OF THE INVENTION
The current application is directed to a method of producing a low solids,
essentially water-free bitumen product from an oil sand/solvent slurry
produced by an
existing solvent extraction process of mined oil sand. It was surprisingly
discovered that
by conducting the method of the present invention, one or more of the
following benefits
may be realized:
(1) The invention may be integrated with an existing solvent extraction
process in which diluted bitumen is extracted from oil sand using either a
single solvent
(e.g., a light solvent such as C3-C9 paraffinic solvent) or a combination of
solvents (e.g.,
a high-flash point heavy solvent and a light solvent).
(2) The quality of the diluted bitumen product is enhanced by sufficient
mixing. There is about 35% improvement of the product quality by using a high
energy-
dissipation impeller as compared to a low energy-dissipation impeller.
(3) High-solids asphaltene-rich tails produced by the invention are further
treated without releasing captured fines in the solvent extraction process.
(4) Light solvent recovered by the invention is recycled in both the
solvent
extraction process and the bitumen solids content reduction process of the
invention.
(5) One solvent extraction process uses a combination of a heavy solvent
and
a light solvent. Using the method of the invention, a low-solids, water-free
stream is
produced which comprises predominantly bitumen and heavy solvent which may be
a
light gas oil. The stream may contain less than about 500 mg/kg solids on dry
bitumen
basis. The stream may be pipelined either to a distillation unit for heavy
solvent
recovery prior to sale, or to market directly as "synthetic bitumen" or
"synbit" including
the heavy solvent as a diluent. The synbit has a filterable solids content of
less than
about 300 mg/kg which is considered fungible in refineries.
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(6)
One solvent extraction process uses only a light solvent. Using the
method of the invention, a low-solids, water-free stream is produced which
comprises
predominantly bitumen.
Use of the present invention improves reduction of water and solids content in
a
final bitumen product, thereby in turn producing a low-solids marketable
bitumen
product with a reasonably high bitumen recovery. The bitumen recovery in the
final
bitumen product is generally greater than about 90% including the bitumen loss
in the
solvent extraction process.
Thus, broadly stated, in one aspect of the invention, a method of producing a
marketable bitumen product having low solids and essentially no water from an
oil
sand/solvent slurry produced in a solvent extraction process of mined oil sand
is
provided, comprising:
= subjecting the oil sand/solvent slurry to solid-liquid separation to
produce a high-
solids diluted bitumen stream and a first solids stream;
= mixing the high-solids diluted bitumen with a light solvent (LS) stream in
at least
a first mixer to produce a diluted bitumen-LS mixture;
= subjecting the diluted bitumen-LS mixture to separation in at least a
first
separator to produce a low-solids diluted bitumen stream and high-solids
asphaltene-rich tails;
= recovering the LS from the low-solids diluted bitumen in a diluent
recovery unit to
produce the marketable bitumen product;
= washing the high-solids asphaltene-rich tails with LS and combining the
washed
high-solids asphaltene-rich tails with the first solids stream to produce a
second
solid stream; and
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= drying the second solid stream in a dryer to recover the LS and produce
dry
tailings.
In one embodiment, the LS is a paraffinic C8-C7 solvent. In one embodiment,
wherein both a heavy solvent (HS) and a light solvent (LS) are used in solvent
extraction, the LS to bitumen mass ratio ranges from about 2.5 to about 4Ø
In one embodiment, the LS is a paraffinic C5-C8 solvent. In one embodiment,
wherein only LS is used in solvent extraction, the LS to bitumen mass ratio
ranges from
about 1.2 to about 2Ø
In one embodiment, the bitumen recovery is greater than about 90 wt%. In
another embodiment, the bitumen recovery is greater than about 88 wt%.
BRIEF DESCRIPTION OF THE DRAWINGS
Referring to the drawings wherein like reference numerals indicate similar
parts
throughout the several views, several aspects of the present invention are
illustrated by
way of example, and not by way of limitation, in detail in the figures,
wherein:
FIG. 1 is a diagram showing, in general, one embodiment of a bitumen solids
content
reduction process of the present invention.
FIG. 2 is a diagram showing, in general, one embodiment of a bitumen solids
content
reduction process of the present invention.
FIG. 3 shows two graphs of the solids concentration in dilbit (mg/kg) versus
settling time
(minutes).
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
The detailed description set forth below in connection with the appended
drawings is intended as a description of various embodiments of the present
invention
and is not intended to represent the only embodiments contemplated by the
inventor.
The detailed description includes specific details for the purpose of
providing a
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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.
The present invention relates generally to a method of reducing solids content
in
high-solids diluted bitumen produced by solvent extraction of mined oil sand.
Reduction
of bitumen water and solids content improves bitumen product quality, thereby
in turn
producing a low-solids marketable bitumen product with a reasonably high
bitumen
recovery. The method of the present invention is integrated with an existing
solvent
extraction process. High-solids asphaltene-rich tails produced by the method
of the
invention are further treated without releasing captured fines in the solvent
extraction
process. Light solvent recovered by the method of the invention is reused in
the solvent
extraction process and in the bitumen solids content reduction process of the
invention.
The method of the invention thus imparts environmental and economic benefits.
Several embodiments of the method for reducing solids content in high-solids
diluted bitumen produced by an existing solvent extraction process are
described
herein. The solvent extraction process may be, but is not limited to, one
described
below or one described in the background section. The embodiment of the
invention
shown in FIG. 1 integrates the solvent extraction process as described in
Canadian
Patent Application No. 2,751,719, wherein bitumen is extracted from oil sand
using a
combination of high-flash point heavy solvent (HS) and light solvent (LS). The
embodiment of the present invention shown in FIG. 2 integrates a solvent
extraction
process wherein bitumen is extracted from oil sand using only LS.
As used herein, the term "heavy solvent" or "HS" refers to a solvent with a
typical
boiling range of 177-480 C and generally includes hydrocarbon liquids in the
C10 to 030
range such as light gas oil and diesel.
As used herein, the term "light solvent" or "LS" means a solvent with a
typical
boiling range of 36-126 C and generally includes hydrocarbon liquids in the C5
to C8
range such as pentane, hexane, cyclohexane, heptanes and octane.
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=
FIG. 1 shows one embodiment of the method of the present invention integrated
with an existing solvent extraction process which uses a combination of HS and
LS.
The solvent extraction process is shown separated with a dashed line in FIG.
1. The oil
sand is delivered in a dry form from a mine to a slurry preparation and
conditioning unit
(e.g., a tumbler/crusher circuit) which is located in an extraction plant. The
oil sand is
prepared, conditioned, crushed, and mixed with a HS and a LS-rich in two
stages to
form an oil sand/solvent slurry 100. As used herein, a "LS-rich stream" is
defined as a
stream containing more than about 50 wt% LS. The oil sand/solvent slurry 100
is
passed through a first solid-liquid separator 10, e.g., a filter, to produce a
high-solids
diluted bitumen stream or high-solids "dilbit" 105 and a filter cake 101.
The filter cake 101 is fed to a repulper 11 in which it is vigorously mixed
with a
LS-dominant stream pumped into the repulper 11. As used herein, a "LS-dominant
stream" is defined as a stream containing more than about 80 wt% LS. The
repulper 11
may be a baffled tank agitated with impellers. After repulping, the repulped
filter cake
102 is passed through a second solid-liquid separator 12, e.g., a top-loading
filter, to
produce a first filtrate stream 130 and a first filter cake 103a. The first
filter cake 103a is
then washed with a pure LS stream and a second filtrate stream 132 and a
second filter
cake 103b are separated from the second solid-liquid separator 12. It is
understood
that the second filtrate stream 132 and second filter cake 103b could be
produced in a
third, separate, solid-liquid separator. The first filtrate stream 130 and the
second
filtrate stream 132 may be recycled back to the solvent extraction process as
the LS-
rich stream to produce the oil sand/solvent slurry and the repulper 11 as the
LS-
dominant stream, respectively. The filter cake 103b is dried in a solids dryer
13 to
recover the LS and to produce dry tailings 104 for disposal.
The high-solids diluted bitumen 105 contains about 1 wt% solids on dry bitumen
basis. The high-solids diluted bitumen 105 is sufficiently mixed with a LS
stream 110 in
a suitable mixer 14 to produce a diluted bitumen-LS mixture 106. In one
embodiment,
the LS stream 110 comprises C6-C7 paraffins. In another embodiment, the LS
stream
110 comprises 05-08 paraffins.
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=
The flow rate of LS stream 110 is adjusted so that the mass ratio of LS stream
110 to high-solids diluted bitumen 105 is controlled to be in the range of
about 0.5 to
about 1Ø Since the high-solids diluted bitumen 105 in this embodiment
already
contains LS, the mass ratio of LS to bitumen is about 2.5 to about 4.0 in the
diluted
bitumen-LS mixture 106. At such a ratio, only moderate asphaltene
precipitation occurs
due to the presence in high-solids diluted bitumen 105 of an aromatics-rich
HS, a light
gas oil fraction produced from an oil sand bitumen upgrading unit.
In one embodiment, the diluted bitumen-LS mixture 106 is fed to a separator 15
in which it is subjected to separation to produce low-solids diluted bitumen
107 and
high-solids asphaltene-rich tails stream 108. Since the solids and asphaltene
from the
diluted bitumen-LS mixture 106 settle in the separator 15, the low-solids
diluted bitumen
107 may contain less than about 500 mg/kg filterable solids and about 1000
mg/kg
water on dry bitumen basis. In one embodiment, separator 15 is a gravity
settler. In
another embodiment, separator 15 is a general solid-liquid separator that
includes a
bank of centrifuges.
The low-solids diluted bitumen 107 is fed to a diluent recovery unit 16 to
recover
the LS stream 110. Any manner of recovering the LS stream 110 from the low-
solids
diluted bitumen 107 may be used. In one embodiment, the LS stream 110 is
recovered
by flashing off from the low-solids diluted bitumen 107. The recovered LS
stream 110
can be recycled in both the method of the invention and the solvent extraction
process.
In one embodiment, a greater portion of the recovered LS stream 110 is reused
in the
mixer 14, while a lesser portion 111 of the recovered LS stream 110 is reused
in the
solvent extraction process.
Removal of the LS stream 110 from the low-solids diluted bitumen 107 produces
a low-solids, water-free stream 109 comprising predominantly bitumen and HS.
In one
embodiment, the stream 109 (also referred to herein as the marketable bitumen
product) contains less than about 500 mg/kg solids on dry bitumen basis. In
one
embodiment, the HS is a light gas oil. The stream 109 may be pipelined either
to a
distillation unit for HS recovery prior to sale, or to market directly as
synthetic bitumen or
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"synbit" including the HS as a diluent. In one embodiment, the synbit has a
filterable
solids content of less than about 300 mg/kg which is considered fungible in
refineries.
At this stage, the method of the invention is integrated with the existing
solvent
process. The high-solids asphaltene-rich tails stream 108 enters the solvent
extraction
process downstream of the repulper 11 to avoid liberating the captured fines
through
agitation. The tails stream 108 is fed to the second solid-liquid separator 12
only after
passage of filtrate stream from the repulped slurry 102 through the second
solid-liquid
separator 12 and formation of a filter cake 103, which is a precursor of first
filter cake
103a. The liquids of the tails stream 108 drain through the filter cake 103,
while highly
viscous asphaltene fine-solids tails are retained by the top layer of the
filter cake 103 to
form first filter cake 103a. The filter cake 103a is washed at least once with
LS, for
example light paraffinic solvent 111. After washing and draining, the solids
in tails
stream 108, now mixed with first filter cake 103a to form second filter cake
103b, are
relatively dry. Second filter cake 103b is further dried in the solids dryer
13 to recover
LS as part of the solvent extraction process. The subsequent dry tailings 104
thus
include the asphaltene-fine solids tails and spent oil sand solids. The heat
duty to
recover the LS from tails stream 108 is minimized following this integration.
In one embodiment, the total hydrocarbon loss including maltene, asphaltene
and HS after the treatment of the tails stream 108 is less than about 5 wt% on
oil sand
bitumen basis. Taking into account a typical hydrocarbon loss of about 4 wt%
on oil
sand bitumen basis for the existing solvent extraction process, the combined
bitumen
recovery is greater than about 90%.
FIG. 2 shows one embodiment of the method of the present invention integrated
with an existing solvent extraction process wherein bitumen is extracted from
oil sand
using only LS. However, the method of the invention is generally the same as
that
shown in FIG. 1.
The solvent extraction process is shown separated with a dashed line in FIG.
2.
The oil sand is delivered in a dry form from a mine to a slurry preparation
and
conditioning unit (e.g., a tumbler/crusher circuit) which is located in an
extraction plant.
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=
The oil sand is prepared, conditioned, crushed, and mixed with a LS-rich
stream to form
an oil sand/solvent slurry 300. The oil sand/solvent slurry 300 is passed
through a
solid-liquid separator 30, e.g., a top-loaded filter, to separate high-solids
diluted bitumen
or high solids "dilbit" 303 and a first filter cake 301a. The first filter
cake 301a is then
washed with a pure LS stream. A second filtrate stream 332 and a second filter
cake
301b are separated from the solid-liquid separator 30. Second filtrate stream
332 may
be recycled back to the solvent extraction process, e.g., an oil sand/solvent
slurry
preparation unit, as the LS-rich stream. The second filter cake 301b is dried
in a solids
dryer 31 to recover the LS and to produce dry tailings 302 for disposal.
The high-solids diluted bitumen 303 is sufficiently mixed with a LS stream 308
in
a mixer 32 to produce a diluted bitumen-LS mixture 304. In one embodiment, the
LS
stream 308 comprises 05-08 paraffins.
The mass ratio of LS to bitumen in stream 304 is controlled to be in the range
of
about 1.2 to about 2.0 by adjusting the flow rate of the LS stream 308.
The diluted bitumen-LS mixture 304 is fed to a separator, e.g., a gravity
settler,
33 in which it is subjected to separation to produce low-solids diluted
bitumen 305 and
high-solids asphaltene-rich tails stream 306. In one embodiment, the separator
33 is a
general solid-liquid separator that includes a bank of centrifuges.
The low-solids diluted bitumen 305 is fed to a diluent recovery unit 34 to
recover
the LS stream 308. Any manner of recovering the LS stream 308 from the low-
solids
diluted bitumen 305 may be used. In one embodiment, the LS stream 308 is
recovered
by flashing off from the low-solids diluted bitumen 305. The recovered LS
stream 308 is
recycled in both the method of the invention and the solvent extraction
process. In one
embodiment, a greater portion of the recovered LS stream 308 is reused in the
mixer
32, while a lesser portion 309 of the recovered LS stream 308 is reused in the
solvent
extraction process.
Removal of the LS stream 308 from the low-solids diluted bitumen 305 produces
a low-solids, essentially water-free stream 307 comprising predominantly
bitumen. In
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one embodiment, the stream 307 contains less than about 400 mg/kg solids on
dry
bitumen basis.
At this stage, the method of the invention is integrated with the existing
solvent
process. The high-solids asphaltene-rich tails stream 306 enters the solvent
extraction
process downstream of any slurry preparation/conditioning unit to avoid
liberating the
captured fines through agitation. The tails stream 306 is fed to the solid-
liquid separator
30 only after passage of the liquid in the oil sand/solvent slurry 300 through
the solid-
liquid separator 30 and formation of a filter cake 301, which is a precursor
of first filter
cake 301a. The liquids of the high solids tails stream 306 drain through the
filter cake
301, while highly viscous asphaltene fine-solids tails are retained by the top
layer of the
filter cake 301 to form first filter cake 301a. The first filter cake 301a is
washed at least
once with fresh LS. After washing and draining, the solids in the high-solids
tails stream
306, now mixed in second filter cake 301b, are relatively dry. Second filter
cake 301b is
further dried in the solids dryer 31 to recover LS as part of the solvent
extraction
process. The subsequent dry tailings 302 thus include the asphaltene-fine
solids tails
and spent oil sand solids. The heat duty to recover the LS from high-solids
tails stream
306 is minimized following this integration.
In one embodiment, the total hydrocarbon loss including maltene and asphaltene
after the treatment of the tails stream 306 is less than about 6 wt% on oil
sand bitumen
basis. Taking into account a typical hydrocarbon loss of about 6 wt% on oil
sand
bitumen basis for the existing solvent extraction process, the combined
bitumen
recovery is greater than about 88 wt%.
In the embodiments shown in FIGS. 1 and 2, the mixer 14 and 32 may comprise
a high energy-input impeller. In one embodiment, the impeller comprises a
Rushton
turbine which is a radial flow impeller having a flat disk upon which flat,
concave, or
semi-circular blades are vertically mounted. Preferably, the Ruston turbine is
run at a
speed that causes the mixed liquid to be in a fully turbulent regime in order
to enhance
collision and aggregation between individual asphaltene particles and
asphaltene
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particles-fine solids. The duration of mixing may range from about 1 minute to
about 10
minutes.
In the embodiments shown in FIGS. 1 and 2, the gravity settler 15 and 33 may
comprise any suitable apparatus which facilitates gravity settling including,
but not
limited to, a gravity settling vessel and an inclined plate separator ("IPS").
An IPS refers
is an apparatus comprising a plurality of stacked inclined plates onto which a
mixture to
be separated may be introduced so that the mixture passes along the plates in
order to
achieve separation of components of the mixture.
Exemplary embodiments of the present invention are described in the following
Examples, which are set forth to aid in the understanding of the invention,
and should
not be construed to limit in any way the scope of the invention as defined in
the claims
which follow thereafter.
Example 1
A dilbit product of about 620 g containing approximately 33 wt% bitumen, 33
wt%
virgin light gas oil and 34 wt% heptane was mixed with additional heptane
using various
impellers at 50 C. The hydrocarbon mixture of about 1000 g contained
approximately
wt% bitumen, 20 wt% virgin light gas oil and 60 wt% heptane. The mixed
hydrocarbon sample was allowed to settle in a vessel at 50 C.
FIG. 3 shows the filterable solids concentration reduction in the top 1-2 cm
of the
20 mixed hydrocarbon sample during settling. "RT" stands for Rushton
turbine which is an
impeller with high levels of energy dissipation; "PBT" stands for pitched
blade turbine
which is a medium energy-dissipation impeller; and "A310" is a hydrofoil which
is a
relatively low energy-dissipation impeller. The mixing time was 5 minutes,
except for
one RT mixing case of 10 minutes. The average filterable solids concentrations
at 20
minutes settling time are shown in Table 1. There is about 35% improvement of
the
product quality by using a high energy-input impeller (RT) as compared to the
low
energy-input impeller (A310).
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Table 1.
Impeller Type Solids concentration in Solids concentration on dry
bitumen
dilbit (mg/kg) basis (mg/kg)
RT 90 450
PBT 113 565
A310 140 700
Example 2
An oil sand sample containing 8.9 wt% bitumen and 38% fines in its solids was
extracted with two solvents: virgin light gas oil and heptane in a batch
apparatus. The
oil sand/solvent slurry proceeded through four filtration stages with a
repulping step
between the second and third stages. An asphaltene and solids-rich tails
sample from
Example 1 was added to the top of the filter cake after the third stage
filtration.
Alternately, the tails sample was added to the repulper before the third stage
filtration.
The tails sample mass is about 5% of the oil sand mass.
Table 2 shows the filterable solids concentrations in four filtrates for three
cases:
the control (i.e., no tails addition); addition of tails after repulping and
third stage
filtration; and addition of tails during repulping. The first and second stage
filtrates
varied slightly in their solids contents due to the variation in oil sand
feeds. The post-
third stage tails addition shows no significant change of the solids
concentrations in the
third and fourth stage filtrates as compared to the control case, indicating
that captured
fines in the tails sample were retained by the filter cake. The tails addition
during
repulping shows drastic increase of the solids concentration in the third
stage filtrate,
indicating that captured fines in the tails sample were released during
repulping. Since
all filtrates except the first stage filtrate are recycled in the process, the
released solids
will eventually reach the first stage filtrate (product) which is undesirable.
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Table 2.
Filtrate No Tails Addition Post-Third Stage Tails
Addition
(mg/kg) Tails Addition During
Repulping
(mg/kg) _ (mg/kg)
First Stage 2270 3600 3360
Second Stage 1750 2120 2120
Third Stage 390 320 10530
Fourth Stage 100 150 840
Table 3 shows the variations in filter #2 process rate including third and
fourth
stage filtrations and total hydrocarbon (bitumen, light gas oil and
asphaltene) loss as a
result of adding a tails stream on post-third stage filter cake. The results
indicate about
15% reduction in filter process rate and 3% increase (on oil sand bitumen
basis) in
hydrocarbon loss compared to the control case (i.e., no tails addition). This
sample of
oil sand was aged and poorer in quality than typical fresh oil sands, which
resulted in
higher hydrocarbon loss in the control case.
Table 3.
Parameter No Tails Addition Post-Third Stage
Tails Addition
Filter #2 Process Rate (t/m2h) 14.1 11.9
Hydrocarbon Loss on Oil Sand 8.5 11.3
Bitumen Basis (wt%)
The scope of the claims should not be limited by the preferred embodiments set
forth in the examples, but should be given the broadest interpretation
consistent with the
description as a whole.
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