U.S. patent application number 14/110570 was filed with the patent office on 2014-02-06 for method of processing a bituminous feed using an emulsion.
The applicant listed for this patent is Emilio Alvarez, Thomas R. Palmer, Fritz Pierre, Jr., Brian C. Speirs. Invention is credited to Emilio Alvarez, Thomas R. Palmer, Fritz Pierre, Jr., Brian C. Speirs.
Application Number | 20140034553 14/110570 |
Document ID | / |
Family ID | 47070987 |
Filed Date | 2014-02-06 |
United States Patent
Application |
20140034553 |
Kind Code |
A1 |
Palmer; Thomas R. ; et
al. |
February 6, 2014 |
Method of Processing a Bituminous Feed Using an Emulsion
Abstract
The present disclosure relates to a method of processing a
bituminous feed. The bituminous feed is contacted with a bridging
liquid-in-extraction liquor emulsion to form a slurry. Solids in
the slurry are agglomerated, using agitation, to form an
agglomerated slurry comprising agglomerated solids and a low solids
bitumen extract. The agglomerates are then separated from the low
solids bitumen extract. Emulsifying the bridging liquid prior to
contacting it with the oil sands may reduce the amount of energy
required for the agglomeration process. Other potential benefits
may include the production of smaller and more uniform
agglomerates. The former may lead to higher bitumen recoveries and
the latter may improve the solid-liquid separation rate.
Inventors: |
Palmer; Thomas R.; (Lima,
NY) ; Speirs; Brian C.; (Calgary, CA) ;
Pierre, Jr.; Fritz; (Humble, TX) ; Alvarez;
Emilio; (Missouri City, TX) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Palmer; Thomas R.
Speirs; Brian C.
Pierre, Jr.; Fritz
Alvarez; Emilio |
Lima
Calgary
Humble
Missouri City |
NY
TX
TX |
US
CA
US
US |
|
|
Family ID: |
47070987 |
Appl. No.: |
14/110570 |
Filed: |
March 9, 2012 |
PCT Filed: |
March 9, 2012 |
PCT NO: |
PCT/US12/28557 |
371 Date: |
October 8, 2013 |
Current U.S.
Class: |
208/390 |
Current CPC
Class: |
C10G 2300/44 20130101;
C10G 1/04 20130101; C10G 1/045 20130101; C10G 2300/80 20130101;
C10G 2300/805 20130101; B01D 3/009 20130101 |
Class at
Publication: |
208/390 |
International
Class: |
C10G 1/04 20060101
C10G001/04 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 27, 2011 |
CA |
2738194 |
Claims
1. A method of processing a bituminous feed, the method comprising:
a) contacting the bituminous feed with a bridging
liquid-in-extraction liquor emulsion, to form a slurry, wherein the
extraction liquor comprises a solvent; b) agglomerating solids
within the slurry, using agitation, to form an agglomerated slurry
comprising agglomerates and a low solids bitumen extract; and c)
separating the agglomerates from the low solids bitumen
extract.
2. The method of claim 1, wherein the emulsion comprises bridging
liquid droplets, at least 80 wt. % of which are sized between one
of 1 and 100 .mu.m and 1 and 10 .mu.m.
3. (canceled)
4. The method of claim 1, wherein the emulsion comprises 5 wt. % to
50 wt. % of the bridging liquid.
5. The method of claim 1, wherein the emulsion is one of unstable
and stable.
6. (canceled)
7. The method of claim 1, further comprising, prior to step a),
forming the emulsion.
8. The method of claim 7, wherein the forming of the emulsion
comprises one of (i) adding an additive to facilitate the formation
of the emulsion, (ii) using an ultrasonic emulsifier, (iii) using a
tubular mixer, static mixer, blender, liquid jet mixer, or a
combination thereof.
9. The method of claim 8, wherein the additive comprises one of an
alkaline solution and a surfactant.
10-12. (canceled)
13. The method of claim 1, wherein the emulsion is mixed with the
bituminous feed using a liquid jet.
14. The method of claim 1, further comprising recovering the
solvent from the low solids bitumen extract to form a bitumen
product.
15. The method of claim 14, further comprising washing the
agglomerates of step c) with one of (i) the solvent recovered from
the low solids bitumen extract and (ii) a solvent, which solvent is
the same as or different from the solvent of step a), to extract
additional bitumen and to form washed agglomerates.
16. (canceled)
17. The method of claim 1, further comprising recovering solvent
from one of (i) the agglomerates, which have been separated from
the low solids bitumen extract and (ii) the washed
agglomerates.
18. (canceled)
19. The method of claim 1, wherein the extraction liquor comprises
the solvent of step a) and bitumen in an amount of 10 to 50 wt.
%.
20. The method of claim 1, further comprising, prior to step a),
contacting the bituminous feed with additional extraction liquor to
begin extraction.
21. The method of claim 1, wherein the bridging liquid is one of
water and an aqueous solution.
22. (canceled)
23. The method of claim 1, wherein at least 80 wt. % of the
agglomerates of step c) are between 0.1 and 1 mm.
24. The method of claim 1, wherein the agglomerated slurry has a
solids content of 20 to 70 wt. %.
25. The method of claim 1, wherein the solvent comprises an organic
solvent or a mixture of organic solvents, wherein the solvent
comprises a paraffinic solvent, a cyclic aliphatic hydrocarbon, or
a mixture thereof, and wherein the paraffinic solvent comprises an
alkane, a natural as condensate, a distillate from a fractionation
unit, or a combination thereof, containing more than 40% small
chain paraffins of 5 to 10 carbon atoms.
26-27. (canceled)
28. The method of claim 25, wherein the alkane comprises a normal
alkane, an iso-alkane, or a combination thereof and wherein the
alkane comprises heptane, iso-heptane, hexane, iso-hexane, pentane,
iso-pentane, or a combination thereof.
29. (canceled)
30. The method of claim 28, wherein the cyclic aliphatic
hydrocarbon comprises a cycloalkane of 4 to 9 carbon atoms and
wherein the cycloalkane comprises cyclohexane, cyclopentane, or a
mixture thereof.
31. (canceled)
32. The method of claim 1, wherein one of (i) the solvent comprises
at least 50 wt. % cyclohexanebu, (ii) the extraction liquor
comprises residual solids, (iii) the bridging liquid comprises
solid fines, (iv) bridging liquid has a solids content of less than
40 wt. % and (v) the agglomeration is effected in one or more
vessels.
33-36. (canceled)
37. The method of claim 1, wherein step b) comprises agitating by
mixing, shaking, or rolling.
38. The method of claim 1, wherein a ratio of one of the solvent to
bitumen in the agglomerated slurry is less than 2:1 and emulsion to
slurry is in a range of 1.5 to 0.1 by weight.
39-40. (canceled)
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application claims the benefit of Canadian patent
application number 2,738,194 filed on Apr. 27, 2011 entitled METHOD
OF PROCESSING A BITUMINOUS FEED USING AN EMULSION, the entirety of
which is incorporated herein.
FIELD
[0002] The present disclosure relates generally to the field of
hydrocarbon extraction from mineable deposits, such as bitumen from
oil sands.
BACKGROUND
[0003] Methodologies for extracting hydrocarbon from oil sands have
required energy intensive processing steps to separate solids from
the products having commercial value.
[0004] Solvent extraction processes for the recovery of the
hydrocarbons have been proposed as an alternative to water
extraction of oil sands. However, the commercial application of a
solvent extraction process has, for various reasons, eluded the oil
sands industry. A major challenge to the application of solvent
extraction to oil sands is the tendency of fine particles within
the oil sands to hamper the separation of solids from the
hydrocarbon extract. Solids agglomeration is a technique that can
be used to deal with this challenge.
[0005] Solids agglomeration is a size enlargement technique that
can be applied within a liquid suspension to assist solid-liquid
separation. The process involves agglomerating fine solids, which
are difficult to separate from a liquid suspension, by the addition
of a second liquid. The second liquid preferentially wets the
solids but is immiscible with the suspension liquid. With the
addition of an appropriate amount of the second liquid and a
suitable agitation, the second liquid displaces the suspension
liquid on the surface of the solids. As a result of interfacial
forces between the three phases, the fines solids consolidate into
larger, compact agglomerates that are more readily separated from
the suspension liquid.
[0006] Solids agglomeration has been used in other applications to
assist solid-liquid separation. For example, the process has been
used in the coal industry to recover fine coal particles from the
waste streams produced during wet cleaning treatments (see for
example, U.S. Pat. Nos. 3,856,668 (Shubert); 4,153,419 (Clayfield);
4,209,301 (Nicol et al.); 4,415,445 (Hatem) and 4,726,810
(Ignasiak)). Solids agglomeration has also been proposed for use in
the solvent extraction of bitumen from oil sands. This application
was coined Solvent Extraction Spherical Agglomeration (SESA). A
more recent description of the SESA process can be found in Sparks
et al., Fuel 1992(71); pp 1349-1353.
[0007] Previously described methodologies for SESA have not been
commercially adopted. In general, the SESA process involves mixing
oil sands with a hydrocarbon solvent, adding a bridging liquid to
the oil sands slurry, agitating the mixture in a slow and
controlled manner to nucleate particles, and continuing such
agitation to permit these nucleated particles to form larger
multi-particle spherical agglomerates for removal. The bridging
liquid is preferably water or an aqueous solution since the solids
of oil sands are mostly hydrophilic and water is immiscible with
hydrocarbon solvents.
[0008] The SESA process described by Meadus et al. in U.S. Pat. No.
4,057,486, involves combining solvent extraction with solids
agglomeration to achieve dry tailings suitable for direct mine
refill. In the process, organic material is separated from oil
sands by mixing the oil sands material with an organic solvent to
form a slurry, after which an aqueous bridging liquid is added in
the amount of 8 to 50 wt. % of the feed mixture. By using
controlled agitation, solid particles from oil sands come into
contact with the aqueous bridging liquid and adhere to each other
to form macro-agglomerates of a mean diameter of 2 mm or greater.
The formed agglomerates are more easily separated from the organic
solvent compared to un-agglomerated solids. This process permitted
a significant decrease in water use, as compared with conventional
water-based extraction processes. The multi-phase mixture need only
be agitated severely enough and for sufficient time to intimately
contact the aqueous liquid with the fine solids. The patent
discloses that it is preferable that the type of agitation be a
rolling or tumbling motion for at least the final stages of
agglomeration. These types of motion should assist in forming
compact and spherical agglomerates from which most of the
hydrocarbons are excluded. The formed agglomerates are referred to
as macro-agglomerates because they result from the consolidation of
both the fine particles (sized less than 44 .mu.m) and the coarse
particles (sized greater than 200 .mu.m) found in the oil
sands.
[0009] U.S. Pat. No. 3,984,287 (Meadus et al.) and U.S. Pat. No.
4,406,788 (Meadus et al.) both describe apparatuses for extracting
bitumen from oil sands while forming macro-agglomerates for easy
solid-liquid separation. U.S. Pat. No. 3,984,287 (Meadus et al.)
describes a two vessel agglomeration apparatus. The apparatus
comprises a mixing vessel for agitating the oil sands, the bridging
liquid, and the solvent to form a slurry with suspended
agglomerates. The slurry is screened in order to remove a portion
of the hydrocarbon liquid within which the bitumen product is
dissolved. The agglomerates are then directed to a tapered rotating
drum where they are mixed with additional solvent and bridging
liquid. The additional solvent acts to wash the excess bitumen from
the agglomerates. The additional bridging liquid allows the
agglomerates to grow by a layering mechanism and under the
increasing compressive forces produced by the tapered rotating drum
bed depth. The compressive forces act to preferentially remove
hydrocarbon liquid from the pores of the agglomerates such that,
when optimal operating conditions are imposed, the pores of the
agglomerates end up being filled with only the bridging liquid, and
the solvent that remains on the surface of the agglomerates is
easily recovered. U.S. Pat. No. 4,406,788 (Meadus et al.) describes
a similar apparatus to that of U.S. Pat. No. 3,984,287 (Measdus et
al.), but where the extraction and agglomeration processes occurs
within a single vessel. Within this vessel, the flow of solvent is
counter-current to the flow of agglomerates which results in
greater extraction efficiency.
[0010] The above-mentioned patents describe methods of using the
fines within oil sands and an aqueous bridging liquid to promote
the consolidation of the coarse oil sands particles into compact
macro-agglomerates having minimal entrained hydrocarbons and which
are easily separated from the hydrocarbon liquid by simple
screening. This macro-agglomeration process may be suitable for oil
sands feeds comprising greater than 15 wt % fines. For oil sands
with a lesser amount of fines, the resulting agglomerates show poor
strength and a significant amount of hydrocarbons entrained within
their pores. The inability of the macro-agglomeration process to
produce agglomerates of similar solid-liquid separation
characteristics regardless of oil sands feed grade, is a
limitation. This limitation can be mitigated by using a water and
fine particle slurry as the bridging liquid. U.S. Pat. No.
3,984,287 (Meadus et al.) reveals that middlings of a primary
separation vessel of a water-based extraction process or sludge
from the water-based extraction tailings ponds may be used as the
bridging liquids with high fines content. It has been shown that
when sludge is used as the bridging liquid, the addition of the
same amount of sludge per unit weight of oil sands feed may result
in the production of agglomerates of the same drainage properties
regardless of oil sands quality. The use of sludge, however,
introduces other challenges such as the fact that the appropriate
sludge may not be readily available at the mine site. Furthermore,
the use of sludge as the bridging liquid leads to larger
agglomerates that are more prone to entrapment of bitumen.
[0011] U.S. Pat. No. 4,719,008 (Sparks et al.) describes a process
to address the agglomeration challenge posed by varying ore grades
by means of a micro-agglomeration procedure in which the fine
particles of the oil sands are consolidated to produce agglomerates
with a similar particle size distribution to the coarser grained
particles of the oil sands. Using this micro-agglomeration
procedure, the solid-liquid separation behavior of the agglomerated
oil sands will be similar regardless of ore grade. The
micro-agglomeration process is described as occurring within a
slowly rotating horizontal vessel. The conditions of the vessel
favor the formation of large agglomerates; however, a light milling
action is used to continuously break down the agglomerates. The
micro-agglomerates are formed by obtaining an eventual equilibrium
between cohesive and destructive forces. Since rapid agglomeration
and large agglomerates can lead to bitumen recovery losses owing to
entrapment of extracted bitumen within the agglomerated solids, the
level of bridging liquid is kept as low as possible commensurate
with achieving economically viable solid-liquid separation.
[0012] The micro-agglomeration process described in U.S. Pat. No.
4,719,008 (Sparks et al.) has several disadvantages that have thus
far limited the application of the technology. Some of these
disadvantages will now be described.
[0013] In previously described SESA processes, the bridging liquid
is either added directly to the dry oil sands or it is added to the
oil sands slurry comprising the oil sands and the hydrocarbon
solvent. In the former scenario, bitumen extraction and particle
agglomeration occurs simultaneously. For this reason, the growth of
agglomerates may hamper the dissolution of the bitumen into the
solvent, it may lead to trapping of bitumen within the
agglomerates, and it may result in an overall increase in the
required residence time for bitumen extraction. In the scenario
where the bridging liquid is added to the oil sands slurry,
excessive agglomeration may occur in the locations of bridging
liquid injection. These agglomerates will tend to be larger than
the desired agglomerate size and result in an increase in the
viscosity of the slurry. A higher slurry viscosity may hamper the
mixing needed to uniformly distribute the bridging liquid
throughout the remaining areas of the slurry. Poor bridging liquid
dispersion may result in a large agglomerate size distribution,
which is not preferred.
[0014] An important step in the agglomeration process is the
distribution of the bridging liquid throughout the liquid
suspension. Poor distribution of the bridging liquid may result in
regions within the slurry of too low and too high binging liquid
concentrations. Regions of low bridging liquid concentrations may
have no or poor agglomeration of fine solids, which may result in
poor solid-liquid separation. Regions of high bridging liquid
concentration may have excess agglomeration of solids, which may
result in the trapping of bitumen or bitumen extract within the
large agglomerates. In the process described in U.S. Pat. No.
4,719,008 (Sparks et al.), the milling action of the rotating
vessel acts to both breakup large agglomerates and distribute the
bridging liquid throughout the vessel in order to achieve uniform
agglomerate formation. In a commercial application, the rotating
vessel would need to be large enough to process the high volumetric
flow rates of oil sands. Accomplishing uniform mixing of the
bridging liquid in such a large vessel would require a significant
amount of mixing energy and long residence times.
[0015] Coal mining processes often produce aqueous slurries
comprising fine coal particles. Solids agglomeration has been
proposed as a method of recovering these fine coal particles, which
may constitute up to 30 wt. % of the mined coal. In the solids
agglomeration process, the hydrophobic coal particles are
agglomerated within the aqueous slurry by adding an oil phase as
the bridging liquid. When the aqueous slurry, with bridging liquid,
is agitated, the coal particles become wetted with an oil layer and
adhere to each other to form agglomerates. The hydrophilic ash
particles are not preferentially wetted by the oil phase and, as a
result, remain un-agglomerated and suspended in the aqueous phase.
The agglomerated coal material, with reduced ash content, is
readily separated from the aqueous slurry by mechanical methods
such as screening.
[0016] U.S. Pat. No. 3,856,668 (Shubert) and U.S. Pat. No.
4,209,301 (Nicol et al.) describe a coal agglomeration process
where the oil is first emulsified in water to form an oil-in-water
emulsion before the oil is added to the aqueous slurry. Having the
bridging liquid in the form of an emulsion allows for faster and
more uniform agglomerate formation. The required amount of mixing
energy needed for agglomeration is also significantly reduced
compared to the case where the bridging liquid is added directly to
the aqueous slurry. Additionally, the amount of bridging liquid
needed for effective agglomeration of the coal particles is
reduced.
[0017] U.S. Pat. No. 4,153,419 (Clayfiled et al.) describes a
process for the agglomeration of coal fines within an aqueous
slurry by staged addition of a bridging liquid to the aqueous
slurry. Each agglomeration stage comprises the addition of a
bridging liquid to the slurry, agitation of the mixture, and
removal of agglomerates from the aqueous slurry. The inventors
found that performing the agglomeration process in at least two
stages yielded higher agglomeration of the coal particles as
compared to the case where the same amount of bridging liquid was
added in one agglomeration stage.
[0018] U.S. Pat. No. 4,415,445 (Van Hattem et al.) describes a
process for the agglomeration of coal fines within an aqueous
slurry by the addition of a bridging liquid and the addition of
seed pellets that are substantially larger than the coal fines. The
presence of seed pellets induces agglomerate growth to occur
predominately by a layering mechanism rather than by a coalescence
mechanism. Since the rate of agglomeration occurs much faster by
layering compared to coalescence, the process described therein
allows agglomerates to form very quickly so that, for a given
residence time, a higher throughput of agglomerates can be obtained
compared to the throughput obtainable in the absence of seed
pellets.
[0019] It would be desirable to provide an alternative or improved
method for processing a bituminous feed.
SUMMARY
[0020] The present disclosure relates to a method of processing a
bituminous feed. The bituminous feed is contacted with a bridging
liquid-in-extraction liquor emulsion to form a slurry. Solids in
the slurry are agglomerated, using agitation, to form an
agglomerated slurry comprising agglomerated solids and a low solids
bitumen extract. The agglomerates are then separated from the low
solids bitumen extract. Emulsifying the bridging liquid prior to
contacting it with the bituminous feed may reduce the amount of
energy required for the agglomeration process. Other potential
benefits may include the production of smaller and more uniform
agglomerates. The former may lead to higher bitumen recoveries and
the latter may improve the solid-liquid separation rate.
[0021] In a first aspect, the present disclosure provides a method
of processing a bituminous feed, the method comprising: a)
contacting the bituminous feed with a bridging liquid-in-extraction
liquor emulsion, to form a slurry, wherein the extraction liquor
comprises a solvent; b) agglomerating solids within the slurry,
using agitation, to form an agglomerated slurry comprising
agglomerates and a low solids bitumen extract; and c) separating
the agglomerates from the low solids bitumen extract.
[0022] Other aspects and features of the present disclosure will
become apparent to those ordinarily skilled in the art upon review
of the following description of specific embodiments in conjunction
with the accompanying figures.
BRIEF DESCRIPTION OF THE DRAWINGS
[0023] Embodiments of the present disclosure will now be described,
by way of example only, with reference to the attached Figures.
[0024] FIG. 1 is a flow chart illustrating a disclosed
embodiment.
[0025] FIG. 2 is a schematic illustrating a disclosed
embodiment.
[0026] FIG. 3 is a schematic illustrating a disclosed
embodiment.
[0027] FIG. 4 is a schematic illustrating a disclosed
embodiment.
DETAILED DESCRIPTION
[0028] The present disclosure relates to a method of processing a
bituminous feed using a bridging liquid-in-extraction liquor
emulsion. This method may be combined with aspects of other solvent
extraction processes, including, but not limited to, those
described above in the background section, and those described in
Canadian Patent Application Serial No. 2,724,806 ("Adeyinka et
al."), filed Dec. 10, 2010 and entitled "Processes and Systems for
Solvent Extraction of Bitumen from Oil Sands".
[0029] Prior to describing embodiments specifically related to the
emulsion, a summary of the processes described in Adeyinka et al.
is provided in the following paragraph.
Summary of Processes of Solvent Extraction Described in Adeyinka et
al.
[0030] To extract bitumen from oil sands in a manner that employs
solvent, a solvent is combined with a bituminous feed derived from
oil sands to form an initial slurry. Separation of the initial
slurry into a fine solids stream and coarse solids stream may be
followed by agglomeration of solids from the fine solids stream to
form an agglomerated slurry. The agglomerated slurry can be
separated into agglomerates and a low solids bitumen extract.
Optionally, the coarse solids stream may be reintroduced and
further extracted in the agglomerated slurry. A low solids bitumen
extract can be separated from the agglomerated slurry for further
processing. Optionally, the mixing of a second solvent with the low
solids bitumen extract to extract bitumen may take place, forming a
solvent-bitumen low solids mixture, which can then be separated
further into low grade and high grade bitumen extracts. Recovery of
solvent from the low grade and/or high grade extracts is conducted,
to produce bitumen products of commercial value.
[0031] As outlined in the summary section, and now with reference
to FIG. 1, the present disclosure relates to a method of processing
a bituminous feed. The bituminous feed is contacted with a bridging
liquid-in-extraction liquor emulsion to form a slurry (102). Solids
in the slurry are agglomerated, using agitation, to form an
agglomerated slurry comprising agglomerated solids and a low solids
bitumen extract (104). The agglomerates are then separated from the
low solids bitumen extract (106). Emulsifying the bridging liquid
prior to contacting it with the bituminous feed may reduce the
amount of energy required for the agglomeration process. Other
potential benefits may include the production of smaller and more
uniform agglomerates. The former may lead to higher bitumen
recoveries and the latter may improve the solid-liquid separation
rate.
[0032] The term "bituminous feed" refers to a stream derived from
oil sands that requires downstream processing in order to realize
valuable bitumen products or fractions. The bituminous feed is one
that comprises bitumen along with undesirable components. Such a
bituminous feed may be derived directly from oil sands, and may be,
for example raw oil sands ore. Further, the bituminous feed may be
a feed that has already realized some initial processing but
nevertheless requires further processing. Also, recycled streams
that comprise bitumen in combination with other components for
removal as described herein can be included in the bituminous feed.
A bituminous feed need not be derived directly from oil sands, but
may arise from other processes. For example, a waste product from
other extraction processes which comprises bitumen that would
otherwise not have been recovered, may be used as a bituminous
feed. Such a bituminous feed may be also derived directly from oil
shale oil, bearing diatomite or oil saturated sandstones.
[0033] FIG. 2 is a schematic of a disclosed embodiment with
additional steps including emulsion formation and downstream
solvent recovery. The bridging liquid (202) is dispersed within the
extraction liquor (204) using an emulsifier (206) to form a
water-in-oil type emulsion. This step may be performed off-site.
The emulsion (208) and an oil sands slurry (212) are fed into an
agglomerator (210). One or more agglomerators may be used.
[0034] In one embodiment, dry oil sands (214) are first contacted
with an extraction liquor (216) that is free of any bridging liquid
in a slurry system (217). The mixture is well mixed in order to
dissolve all (or nearly all) of the bitumen within the oil sands.
This oil sands slurry (212) is then mixed with the emulsion (208)
to agglomerate the fine particles. In this embodiment, the bitumen
is first extracted from the oil sands (214) prior to agglomeration
in order to prevent (or limit) the agglomeration process from
hampering the dissolution of bitumen into the extraction liquor.
The composition of the extraction liquor used to produce the oil
sands slurry (212) may be the same or different from the extraction
liquor used to produce the emulsion. In another embodiment, the
emulsion may be directly mixed (218) with the oil sands (214) and
potentially additional extraction liquor (216) so that extraction
and agglomeration occur simultaneously.
[0035] The agglomerated slurry (220), comprising agglomerates and a
low solids bitumen extract, is sent to a solid-liquid separator
(222) to produce a low solids bitumen extract (224) and
agglomerates (226). The low solids bitumen extract is sent to a
solvent recovery unit (228) to recover solvent (230) leaving a
bitumen product (234). The agglomerates are sent to a tailings
solvent recovery unit (236) to recover solvent (238) leaving dry
tailings (240).
[0036] FIG. 3 is a schematic of a disclosed embodiment, where the
emulsion is mixed directly with the oil sands. FIG. 3 also includes
additional steps including emulsion formation and downstream
solvent recovery. The bridging liquid (302) is first dispersed
within the extraction liquor (304) using an emulsifier (306) to
form the emulsion (318). The emulsion (318) is fed into a slurry
system (317). Dry oil sands (314) are fed into the slurry system
(317) and mixed with the emulsion (318) to form an oil sands slurry
(312), which is fed into the agglomerator (310). Extraction liquor
(316) may also be added directly to the slurry system (317).
[0037] The agglomerated slurry (320), comprising agglomerates and a
low solids bitumen extract, is sent to a solid-liquid separator
(322) to produce a low solids bitumen extract (324) and
agglomerates (326). The low solids bitumen extract (324) is sent to
a solvent recovery unit (328) to recover solvent (330) leaving a
bitumen product (334). The agglomerates (326) are sent to a
desolventizer (336) to recover solvent (338) leaving dry tailings
(340). Make-up extraction liquor may also be added.
[0038] The solvent (330) removed from the low solids bitumen
extract (324) is used in the solid-liquid separator (322). The
solid-liquid separator (322) produces extraction liquor (304) for
addition to the emulsifier (306), as described above.
[0039] FIG. 4 is a flow chart of a disclosed embodiment, where the
emulsion is mixed with the oil sands after the oil sands have been
slurried with additional extraction liquor. FIG. 4 also includes
additional steps including emulsion formation and downstream
solvent recovery. The bridging liquid (402) is first dispersed
within the extraction liquor (404) using an emulsifier (406) to
form the emulsion (418). The emulsion (418) is fed into the
agglomerator (410). Dry oil sands (414) and extraction liquor (416)
are fed into the slurry system (417) to form oil sands slurry (412)
which is fed into the agglomerator (410).
[0040] The agglomerated slurry (420), comprising agglomerates and a
low solids bitumen extract, is sent to a solid-liquid separator
(422) to produce a low solids bitumen extract (424) and
agglomerates (426). The low solids bitumen extract (424) is sent to
a solvent recovery unit (428) to recover solvent (430) leaving a
bitumen product (434). The agglomerates (426) are sent to a
desolventizer (436) to recover solvent (438) leaving dry tailings
(440).
[0041] The solvent (430) removed from the low solids bitumen
extract (424) is used in the solid-liquid separator (422). The
solid-liquid separator (422) produces extraction liquor (404) for
addition to the emulsifier (406) or the slurry system (417), as
described above. Make-up extraction liquor may also be added.
Forming the Emulsion
[0042] The emulsion comprises a bridging liquid dispersed in an
extraction liquor, both of which are described below. The emulsion
may be formed with various known liquid-in-liquid emulsifiers.
Exemplary devices include, but are not limited to, tubular mixers,
static mixers, blenders, and liquid jet mixers. In one embodiment,
the emulsion forming device is an ultrasonic emulsifier. This
device is expected to produce micron size bridging liquid droplets
with a lower power requirement than a conventional homogenizer. In
one embodiment, the bridging liquid droplets within the emulsion
are 1 to 100 .mu.m in size, or 1 to 10 .mu.m in size. In one
embodiment, at least 80 wt. % of the bridging liquid droplets
within the emulsion are 1 to 100 .mu.m in size, or are 1 to 10
.mu.m in size.
[0043] Using such an emulsion may enable the formation of
macro-agglomerates or micro-agglomerates from the solids of the
bituminous feed. Macro-agglomerates are agglomerates that are
predominantly greater than 2 mm in diameter. These agglomerates
comprise both the fine particles (less than 44 .mu.m) and sand
grains of the oil sands. Micro-agglomerates are agglomerates that
are predominately less than 1 mm in diameter and they principally
comprise fine particles of the oil sands. It has been found that
for the SESA process described above, the formation of
micro-agglomerates are more suitable for maximizing bitumen
recovery for a range of oil sands grades. In one embodiment, the
agglomerated slurry has a solids content of 20 to 70 wt. %. In one
embodiment, a ratio of emulsion to slurry is in a range of 1.5 to
0.1 by weight.
Unstable or Stable Emulsion
[0044] In one embodiment, an unstable emulsion is used. An unstable
emulsion may reduce the energy needed for the bridging liquid to
contact and attach with the solid particles. It has been shown that
for stable emulsions, kinetic restriction from such factors as
electrical double layer interactions and film thinning
considerations can lead to increased power consumption in the
solids agglomeration process [see Int. J. of Min. Proc. Vol. 4 pp
173-184]. An "unstable emulsion", as used herein, means an emulsion
that begins to segregate during the agglomeration process. However,
it is not desirable to have the unstable emulsion segregate much
faster (for instance an order of magnitude faster) than the
agglomeration process, since this would defeat the purpose of using
an emulsion. The time scale of agglomeration, in one non-limiting
example, may be on the order of minutes, for instance 2 to 5
minutes.
[0045] In another embodiment, a stable emulsion is used. In this
embodiment, a stable emulsion is desirable in order to keep the
bridging liquid droplets within the emulsion small and discreet
during the agglomeration process. The stability of the emulsion may
be provided by the interaction between the bridging liquid and the
asphaltenes dissolved within the extraction liquor. Additional
stabilizing agents may include alkaline additives such as NaOH,
Na.sub.2CO.sub.3 and NH.sub.4OH. Residual solids fines, which may
be found in the extraction liquor, may also act as emulsion
stabilizers. Such fines may also serve as nuclei for solids
agglomeration. A "stable emulsion", as used herein, means an
emulsion that will not segregate during the agglomeration process.
The "stable emulsion" may be thermodynamically or kinetically
stable.
[0046] A surfactant may be added to the emulsion.
Agitation
[0047] Agglomeration is assisted by some form of agitation. The
form of agitation may be mixing, shaking, rolling, or another known
suitable method. The agitation of the feed need only be severe
enough and of sufficient duration to intimately contact the
emulsion with the solids in the feed. Exemplary rolling type
vessels include rod mills and tumblers. Exemplary mixing type
vessels include mixing tanks, blenders, and attrition scrubbers. In
the case of mixing type vessels, a sufficient amount of agitation
is needed to keep the formed agglomerates in suspension. In rolling
type vessels, the solids content of the feed is, in one embodiment,
greater than 40 wt. % so that compaction forces assist agglomerate
formation.
Extraction Liquor
[0048] The extraction liquor comprises a solvent used to extract
bitumen from the bituminous feed. The term "solvent", as used
herein, should be understood to mean either a single solvent, or a
combination of solvents.
[0049] In one embodiment, the extraction liquor comprises a
hydrocarbon solvent capable of dissolving the bitumen. The
extraction liquor may be a solution of a hydrocarbon solvent(s) and
bitumen, where the bitumen content of the extraction liquor may
range between 10 to 50 wt. %. It may be desirable to have dissolved
bitumen within the extraction liquor in order to increase the
volume of the extraction liquor without an increase in the required
inventory of hydrocarbon solvent(s). In cases where non-aromatic
hydrocarbon solvents are used, the dissolved bitumen within the
extraction liquor also increases the solubility of the extraction
liquor towards dissolving additional bitumen.
[0050] The solvent used in the process may include low boiling
point solvents such as low boiling point cycloalkanes, or a mixture
of such cycloalkanes, which substantially dissolve asphaltenes. The
solvent may comprise a paraffinic solvent in which the solvent to
bitumen ratio is maintained at a level to avoid or limit
precipitation of asphaltenes.
[0051] While it is not necessary to use a low boiling point
solvent, when it is used, there is the extra advantage that solvent
recovery through an evaporative process proceeds at lower
temperatures, and requires a lower energy consumption. When a low
boiling point solvent is selected, it may be one having a boiling
point of less than 100.degree. C.
[0052] The solvent selected according to certain embodiments may
comprise an organic solvent or a mixture of organic solvents. For
example, the solvent may comprise a paraffinic solvent, an open
chain aliphatic hydrocarbon, a cyclic aliphatic hydrocarbon, or a
mixture thereof. Should a paraffinic solvent be utilized, it may
comprise an alkane, a natural gas condensate, a distillate from a
fractionation unit (or diluent cut), or a combination of these
containing more than 40% small chain paraffins of 5 to 10 carbon
atoms. These embodiments would be considered primarily a small
chain (or short chain) paraffin mixture. Should an alkane be
selected as the solvent, the alkane may comprise a normal alkane,
an iso-alkane, or a combination thereof. The alkane may
specifically comprise heptane, iso-heptane, hexane, iso-hexane,
pentane, iso-pentane, or a combination thereof. Should a cyclic
aliphatic hydrocarbon be selected as the solvent, it may comprise a
cycloalkane of 4 to 9 carbon atoms. A mixture of C.sub.4-C.sub.9
cyclic and/or open chain aliphatic solvents would be
appropriate.
[0053] Exemplary cycloalkanes include cyclohexane, cyclopentane, or
a mixture thereof.
[0054] If the solvent is selected as the distillate from a
fractionation unit, it may for example be one having a final
boiling point of less than 180.degree. C. An exemplary upper limit
of the final boiling point of the distillate may be less than
100.degree. C.
[0055] A mixture of C.sub.4-C.sub.10 cyclic and/or open chain
aliphatic solvents would also be appropriate. For example, it can
be a mixture of C.sub.4-C.sub.9 cyclic aliphatic hydrocarbons and
paraffinic solvents where the percentage of the cyclic aliphatic
hydrocarbon in the mixture is greater than 50%.
[0056] Extraction liquor may be recycled from a downstream step.
For instance, as illustrated in FIGS. 3 and 4, solvent (330, 430)
recovered in the solvent recovery unit (328, 428), is used to wash
agglomerates, and the resulting stream is then used as extraction
liquor. As a result, the extraction liquor may comprise residual
bitumen and residual solid fines. The residual bitumen increases
the volume of the extraction liquor and it may increase the
solubility of the extraction liquor for additional bitumen
dissolution. Residual solids fines in the extraction liquor may act
as emulsion stabilizers.
[0057] The solvent may also include additives. These additives may
or may not be considered a solvent per se. Possible additives may
be components such as de-emulsifying agents or solids aggregating
agents. Having an agglomerating agent additive present in the
bridging liquid and dispersed in the first solvent may be helpful
in the subsequent agglomeration step. Exemplary agglomerating agent
additives include cements, fly ash, gypsum, lime, brine, water
softening wastes (e.g. magnesium oxide and calcium carbonate),
solids conditioning and anti-erosion aids such as polyvinyl acetate
emulsion, commercial fertilizer, humic substances (e.g. fulvic
acid), polyacrylamide based flocculants and others. Additives may
also be added prior to gravity separation with the second solvent
to enhance removal of suspended solids and prevent emulsification
of the two solvents. Exemplary additives include methanoic acid,
ethylcellulose and polyoxyalkylate block polymers.
Bridging Liquid
[0058] A bridging liquid is a liquid with affinity for the solids
particles in the bituminous feed, and which is immiscible in the
solvent. Exemplary aqueous liquids may be recycled water from other
aspects or steps of oil sands processing. The aqueous liquid need
not be pure water, and may indeed be water containing one or more
salts, a waste product from conventional aqueous oil sand
extraction processes which may include additives, aqueous solutions
with a range of pH, or any other acceptable aqueous solution
capable of adhering to solid particles within an agglomerator in
such a way that permits fines to adhere to each other. An exemplary
bridging liquid is water.
[0059] The bridging liquid may be added to the extraction liquor in
a concentration of less than 50 wt. % of the emulsion. In another
embodiment, the bridging liquid is added to the extraction liquor
in a concentration of less than 25 wt. %. In one embodiment, the
bridging liquid is added in a concentration of between 5 wt. % and
50 wt. % or between 10 wt. % and 25 wt. %. In one embodiment, the
bridging liquid may comprise fine particles (sized less than 44
.mu.m) suspended therein. These fine particles may serve as seed
particles for the agglomeration process. In one embodiment, the
bridging liquid has a solids content of less than 40 wt. %.
Ratio of Solvent to Bitumen for Agglomeration
[0060] The process may be adjusted to render the ratio of the
solvent to bitumen in the agglomerator at a level that avoids
precipitation of asphaltenes during agglomeration. Some amount of
asphaltene precipitation is unavoidable, but by adjusting the
amount of solvent flowing into the system, with respect to the
expected amount of bitumen in the bituminous feed, when taken
together with the amount of bitumen that may be entrained in the
extraction liquor used, can permit the control of a ratio of
solvent to bitumen in the agglomerator. When the solvent is
assessed for an optimal ratio of solvent to bitumen during
agglomeration, the precipitation of asphaltenes can be minimized or
avoided beyond an unavoidable amount. Another advantage of
selecting an optimal solvent to bitumen ratio is that when the
ratio of solvent to bitumen is too high, costs of the process may
be increased due to increased solvent requirements.
[0061] An exemplary ratio of solvent to bitumen to be selected as a
target ratio during agglomeration is less than 2:1. A ratio of
1.5:1 or less, and a ratio of 1:1 or less, for example, a ratio of
0.75:1, would also be considered acceptable target ratios for
agglomeration. For clarity, ratios may be expressed herein using a
colon between two values, such as "2:1", or may equally be
expressed as a single number, such as "2", which carries the
assumption that the denominator of the ratio is 1 and is expressed
on a weight to weight basis.
Slurry System
[0062] The slurry system may optionally be a mix box, a pump, or a
combination of these. By slurrying the extraction liquor together
with the bituminous feed, and optionally with additional additives,
the bitumen entrained within the feed is given an opportunity to
become extracted into the solvent phase prior to agglomeration
within the agglomerator.
Solid-Liquid Separator
[0063] As described above, the agglomerated slurry may be separated
into a low solids bitumen extract and agglomerates in a
solid-liquid separator. The solid-liquid separator may comprise any
type of unit capable of separating solids from liquids, so as to
remove agglomerates. Exemplary types of units include a gravity
separator, a clarifier, a cyclone, a screen, a belt filter, or a
combination thereof.
[0064] The system may contain a solid-liquid separator but may
alternatively contain more than one. When more than one
solid-liquid separation step is employed at this stage of the
process, it may be said that both steps are conducted within one
solid-liquid separator, or if such steps are dissimilar, or not
proximal to each other, it may be said that a primary solid-liquid
separator is employed together with a secondary solid-liquid
separator. When a primary and secondary unit are both employed,
generally, the primary unit separates agglomerates, while the
secondary unit involves washing agglomerates.
[0065] Non-limiting methods of solid-liquid separation of an
agglomerated slurry are described in Canadian Patent Application
Serial No. 2,724,806 (Adeyinka et al.), filed Dec. 10, 2010.
Secondary Stage of Solid-Liquid Separation to Wash Agglomerates
[0066] As a component of the solid-liquid separator, a secondary
stage of separation may be introduced for counter-currently washing
the agglomerates separated from the agglomerated slurry. The
initial separation of agglomerates may be said to occur in a
primary solid-liquid separator, while the secondary stage may occur
within the primary unit, or may be conducted completely separately
in a secondary solid-liquid separator. By "counter-currently
washing", it is meant that a progressively cleaner solvent is used
to wash bitumen from the agglomerates. Solvent involved in the
final wash of agglomerates may be re-used for one or more upstream
washes of agglomerates, so that the more bitumen entrained on the
agglomerates, the less clean will be the solvent used to wash
agglomerates at that stage. The result being that the cleanest wash
of agglomerates is conducted using the cleanest solvent.
[0067] A secondary solid-liquid separator for counter-currently
washing agglomerates may be included in the system or may be
included as a component of a system described herein. The secondary
solid-liquid separator may be separate or incorporated within the
primary solid-liquid separator. The secondary solid-liquid
separator may optionally be a gravity separator, a cyclone, a
screen, or belt filter. Further, a secondary solvent recovery unit
for recovering solvent arising from the solid-liquid separator can
be included. The secondary solvent recovery unit may be a
conventional fractionation tower or a distillation unit.
[0068] When conducted in the process, the secondary stage for
counter-currently washing the agglomerates may comprise a gravity
separator, a cyclone, a screen, a belt filter, or a combination
thereof.
[0069] The solvent used for washing the agglomerates may be solvent
recovered from the low solids bitumen extract, as described with
reference to FIGS. 2 to 4. A second solvent may alternatively or
additionally be used as described in Canadian Patent Application
Serial No. 2,724,806 (Adeyinka et al.) for additional bitumen
extraction downstream of the agglomerator.
Recycle and Recovery of Solvent
[0070] The process may involve removal and recovery of solvent used
in the process.
[0071] In this way, solvent is used and re-used, even when a good
deal of bitumen is entrained therein. Because an exemplary
solvent:bitumen ratio in the agglomerator may be 2:1 or lower, it
is acceptable to use recycled solvent containing bitumen to achieve
this ratio. The amount of make-up solvent required for the process
may depend solely on solvent losses, as there is no requirement to
store and/or not re-use solvent that has been used in a previous
extraction step. When solvent is said to be "removed", or
"recovered", this does not require removal or recovery of all
solvent, as it is understood that some solvent will be retained
with the bitumen even when the majority of the solvent is
removed.
[0072] The system may contain a single solvent recovery unit for
recovering the solvent(s) arising from the gravity separator. The
system may alternatively contain more than one solvent recovery
unit.
[0073] Solvent may be recovered by conventional means. For example,
typical solvent recovery units may comprise a fractionation tower
or a distillation unit. Solvent recovered in this fashion will not
have bitumen entrained therein. This clean solvent may be used in
the last wash stage of the agglomerate washing process so that the
cleanest wash of the agglomerates is performed using the cleanest
solvent.
[0074] The solvent recovered in the process may comprise entrained
bitumen therein, and can thus be re-used as the extraction liquor
for combining with the bituminous feed. Other optional steps of the
process may incorporate the solvent having bitumen entrained
therein, for example in countercurrent washing of agglomerates, or
for adjusting the solvent and bitumen content prior to
agglomeration to achieve the selected ratio within the agglomerator
that avoids precipitation of asphaltenes.
Extraction Step May be Separate from Agglomeration Step
[0075] Solvent extraction may be conducted separately from
agglomeration in certain embodiments of the process. Unlike certain
prior processes, where the solvent is first exposed to the
bituminous feed within the agglomerator, certain embodiments
described herein include contact of the extraction liquor with
bituminous feed prior to the agglomeration step. This has the
effect of reducing residence time in the agglomerator, when
compared to certain previously proposed processes which require
extraction of bitumen and agglomeration to occur simultaneously.
The instant process is tantamount to agglomeration of pre-blended
slurry in which extraction via bitumen dissolution is substantially
or completely achieved separately. Performing extraction upstream
of the agglomerator permits the use of enhanced material handling
schemes whereby flow/mixing systems such as pumps, mix boxes or
other types of conditioning systems can be employed. Additionally,
performing extraction upstream of the agglomerator prevents (or
limits) the agglomeration process from hampering the dissolution of
bitumen into the extraction liquor.
[0076] Because the extraction may occur upstream of the
agglomeration step, the residence time in the agglomerator may be
reduced. One other reason for this reduction is that by adding
components, such as water, some initial nucleation of particles
that ultimately form larger agglomerates can occur prior to the
agglomerator.
Dilution of Agglomerator Discharge to Improve Product Quality
[0077] Solvent may be added to the agglomerated slurry for dilution
of the slurry before discharge into the primary solid-liquid
separator, which may be for example a deep cone settler. This
dilution can be carried out in a staged manner to pre-condition the
primary solid-liquid separator feed to promote higher solids
settling rates and lower solids content in the solid-liquid
separator's overflow. The solvent with which the slurry is diluted
may be derived from recycled liquids from the liquid-solid
separation stage or from other sources within the process.
[0078] When dilution of agglomerator discharge is employed in this
embodiment, the solvent to bitumen ratio of the feed into the
agglomerator is set to obtain from about 10 to about 90 wt. %
bitumen in the discharge, and a workable viscosity at a given
temperature. In certain cases, these viscosities may not be optimal
for the solid-liquid separation (or settling) step. In such an
instance, a dilution solvent of equal or lower viscosity may be
added to enhance the separation of the agglomerated solids in the
clarifier, while improving the quality of the clarifier overflow by
reducing viscosity to permit more solids to settle. Thus, dilution
of agglomerator discharge may involve adding the solvent, or a
separate dilution solvent, which may, for example, comprise an
alkane.
Potential Advantages
[0079] There may be advantages of embodiments described herein as
compared to SESA. It is believed that the bridging liquid to solids
contact, which is needed for agglomeration, can be enhanced if the
bridging liquid is first emulsified in the extraction liquor prior
to mixing it with the oil sands solids. Similar advantages have
been realized in the agglomeration of coal fine particles (see U.S.
Pat. No. 3,856,668 (Shubert) and U.S. Pat. No. 4,209,301 (Nicol et
al.)).
[0080] Previous solids agglomeration processes have required large
energy inputs. Embodiments described herein are expected to reduce
the total energy needed to form the agglomerates. The reduction in
energy may be a result of both a reduction in the required time and
the required power needed for the agglomeration process. A
reduction in residence time may translate to smaller and less
expensive vessels. A reduction in the power requirement means that
that the torque requirements of motors used in certain types of
agglomeration vessels can be reduced. In the case of rotating type
vessels, the required amount of milling may be reduced.
Furthermore, the wear of the internals of the vessels may be
reduced due to a reduction in the required mixing intensity.
[0081] The emulsified bridging liquid is expected to more quickly
and more uniformly distribute within the oil sands slurry. For this
reason, the amount of bridging liquid needed to agglomerate the
fine particles within oil sands slurry is expected to be less than
that which would be required if the bridging liquid was not
emulsified. A reduced amount of bridging liquid may result in
smaller agglomerates which have been shown to result in higher
bitumen recovery values. The improved distribution of bridging
liquid within the oil sands slurry is also expected to result in a
narrower particle size distribution for the agglomerates.
Agglomerates that are more uniform in size may have higher drainage
rates for solid-liquid separation methods such as filtration and
screening.
[0082] In the preceding description, for purposes of explanation,
numerous details are set forth in order to provide a thorough
understanding of the embodiments. However, it will be apparent to
one skilled in the art that these specific details are not
required.
[0083] The above-described embodiments are intended to be examples
only. Alterations, modifications and variations can be effected to
the particular embodiments by those of skill in the art without
departing from the scope, which is defined solely by the claims
appended hereto.
Laboratory Experiments
[0084] Experiments were conducted to test the effectiveness of
using a bridging liquid-in-extraction liquor emulsion to
agglomerate oil sand solids within a slurry. The liquid drainage
rate of the formed agglomerates was used as the experimental
measurement to determine the effectiveness of the agglomeration
process. The agglomerates were also visually inspected for their
size and uniformity.
[0085] Athabasca oil sand was treated in a Soxhlet extractor, with
toluene as the extraction solvent, to remove bitumen and water from
the solids. The oil sand solids were dried overnight in an oven
(100.degree. C.) and then used as the solids in the agglomeration
process. Pure cyclohexane was used as the extraction liquor and
distilled water was used as the bridging liquid. Bitumen was
excluded from the solids and the solvent in order to allow for
visual inspection of the agglomeration process. For each
experiment, a total of 350 g of solids, 311.5 g of cyclohexane, and
38.5 g of water were used. This composition translated to a solids
content of 50 wt. % and a water to solids ratio of 0.11 for the
agglomerated slurry.
[0086] A Parr reactor (series 5100) (Parr Instrument Company,
Moline, Ill., USA) was used as the agglomerator. The reactor vessel
was made of glass that permits direct observation of the mixing
process. A turbine type impeller powered by an explosion proof
motor of 0.25 hp was used. The mixing and agglomeration speed of
the impeller were set to 1000 rpm. This rotation speed allowed the
slurry to remain fluidized at all conditions of the experiments.
The agglomeration experiments were conducted at room temperature
(22.degree. C.).
Experiment 1: Agglomeration by Adding Bridging Liquid Directly to
Solids Slurry
[0087] 350 g of oil sand solids and 311.5 g of cyclohexane were
placed into the Parr reactor vessel. The solids and solvent were
mixed at 1000 rpm for 1 minute to fully homogenize the mixture.
After 1 minute of mixing, water was quickly pored into the vessel
through a sample port. The mixture was then mixed at 1000 rpm for
an additional 2 minutes to agglomerate the solids.
[0088] After the agglomeration process, the impeller was turned off
and the agglomerates were allowed to settle for over 1 minute. The
supernatant was pored into a separate container and the wet solids
were transferred to a Buchner funnel. The solids rested on a filter
paper with a nominal pore size of 170 .mu.m. The filter's effective
area was approximately 8 cm.sup.2. The solids bed height was 10.8
cm. A portion of the collected supernatant was pored on top of the
solids until a liquid height of 1.9 cm formed above the solids
surface. A light vacuum was then applied to the Buchner funnel and
the initial drainage rate of the liquid was recorded. The initial
drainage rate for solids agglomerated by adding bridging liquid
directly to the solids slurry was 0.37 mL/(cm.sup.2sec).
Experiment 2: Agglomeration by First Emulsifying Bridging Liquid
with Solvent and then Adding Emulsion to Solids Slurry
[0089] 38.5 g of water was added to 115.5 g of solvent in a glass
bottle. The mixture was then emulsified by placing the glass bottle
in an ultrasonic bath for 10 minutes. 350 g of oil sand solids and
196 g of cyclohexane were placed into the Parr reactor vessel. The
solids and solvent were mixed at 1000 rpm for 1 minute to fully
homogenize the mixture. After 1 minute of mixing, the emulsion was
quickly pored into the vessel through a sample port. The mixture
was then mixed at 1000 rpm for an additional 2 minutes to
agglomerate the solids.
[0090] After the agglomeration process, the impeller was turned off
and the agglomerates where allowed to settle for over 1 minute. The
supernatant was pored into a separate container and the wet solids
were transferred to a Buchner funnel. The solids rested on a filter
paper with a nominal pore size of 170 .mu.m. The filter's effective
area and the funnel's cross-sectional area were approximately 8 cm.
The solids bed height was 10.8 cm. A portion of the collected
supernatant was pored on top of the solids until a liquid height of
1.9 cm formed above the solids surface. A light vacuum was then
applied to the Buchner funnel and the initial drainage rate of the
liquid was recorded. The initial drainage rate for solids
agglomerated by first emulsifying the bridging liquid with solvent
and then adding emulsion to solids slurry was approximately 2.1
mL/(cm.sup.2sec). This drainage rate was approximately 5.7 times
greater than that of agglomerates formed without first emulsifying
the bridging liquid.
* * * * *