Note: Descriptions are shown in the official language in which they were submitted.
CA 02867357 2014-10-16
METHODS FOR PROCESSING A BITUMINOUS FEED
BACKGROUND
Field of Disclosure
[0001] The disclosure relates generally to the field of oil sand
processing. More
specifically, the disclosure relates to methods for processing a bituminous
feed.
Description of Related Art
[0002] This section is intended to introduce various aspects of the art,
which may be
associated with the present disclosure. This discussion is believed to assist
in providing a
framework to facilitate a better understanding of particular aspects of the
present disclosure.
Accordingly, it should be understood that this section should be read in this
light, and not
necessarily as admissions of prior art.
[0003] Modern society is greatly dependent on the use of hydrocarbon
resources for
fuels and chemical feedstocks. Hydrocarbons are generally found in subsurface
formations
that can be termed "reservoirs." Removing hydrocarbons from the reservoirs
depends on
numerous physical properties of the subsurface formations, such as the
permeability of the
rock containing the hydrocarbons, the ability of the hydrocarbons to flow
through the
subsurface formations, and the proportion of hydrocarbons present, among other
things.
Easily harvested sources of hydrocarbons are dwindling, leaving less
accessible sources to
satisfy future energy needs. As the costs of hydrocarbons increase, the less
accessible sources
become more economically attractive.
[0004] Recently, the harvesting of oil sand to remove heavy oil has
become more
economical. Hydrocarbon removal from oil sand may be performed by several
techniques.
For example, a well can be drilled to an oil sand reservoir and steam, hot
air, solvents, or a
combination thereof, can be injected to release the hydrocarbons. The released
hydrocarbons
may be collected by wells and brought to the surface. In another technique,
strip or surface
mining may be performed to access the oil sand, which can be treated with hot
water, steam or
solvents to extract the heavy oil. This other technique may be referred to as
a water-based
extraction process (WBE). The WBE is a commonly used process to extract
bitumen from
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mined oil sand. In another technique, a non-water-based extraction process can
be used to
treat the strip or surface mined oil sand. The non-water-based extraction
process may be
referred to as a solvent-based recovery process. The commercial application of
a solvent-
based recovery process has, for various reasons, eluded the oil sand industry.
A major
challenge associated with the solvent based extraction process is the tendency
of fine particles
within the oil sand to hamper the separation of solids from the heavy oil
(e.g., bitumen)
extracted. The fine particles that remain with the bitumen have an adverse
impact on the
transport of the bitumen within pipelines and have a negative impact on the
downstream
upgrading and/or refining of the bitumen. For these reasons, it is desirable
to reduce the
solids content of the bitumen to a value much less than 1 weight (wt.) %.
Another major
challenge to the application of a solvent-based recovery process for oil sand
is the recovery of
solvent from the bitumen-free solids. This solvent-based recovery process is
often energy
intensive and limits the economics of the overall solvent-based recovery
process.
[0005] A
solid agglomeration process has been proposed for use in the solvent-based
recovery process. The solid agglomeration process was coined Solvent
Extraction Spherical
Agglomeration (SESA). Previously described methodologies for SESA have not
been
commercially adopted. In general, the SESA process involves mixing oil sand
with a
hydrocarbon solvent to form an oil sand slurry, adding an aqueous bridging
liquid to the oil
sand slurry to form a mixture, agitating the mixture in a slow and controlled
manner to
nucleate particles, and continuing such agitation so as to permit these
nucleated particles to
form larger multi-particle spherical agglomerates for removal. The aqueous
bridging liquid
may be water or an aqueous solution since the solids of oil sand are mostly
hydrophilic and
water is immiscible to hydrocarbon solvents. The aqueous bridging liquid
preferentially wets
the solids. With the right amount of the aqueous bridging liquid and suitable
agitation of the
slurry; the aqueous bridging liquid displaces the suspension liquid on the
surface of the solids.
As a result of interfacial forces among three phases (i.e. the aqueous
bridging liquid, the
suspension liquid, and the solids), fine particles within the solids
consolidate into larger,
compact agglomerates that are more readily separated from the suspension
liquid.
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[0006]
The SESA process described by Meadus et al. in U.S. Patent No. 4,057,486
involves combining solvent extraction with solids agglomeration to achieve dry
tailings
suitable for direct mine refill. Organic material is separated from oil sand
by mixing the oil
sand material with an organic solvent to form a slurry, after which an aqueous
bridging liquid
is added in an amount of 8 to 50 weight percent (wt.%) of the feed mixture. By
using
controlled agitation, solid particles from oil sand come into contact with the
aqueous bridging
liquid and adhere to each other to form macro-agglomerates with a mean
diameter of 2
millimeters (mm) or greater. The macro-agglomerates are more easily separated
from the
organic solvent compared to un-agglomerated solids. The macro-agglomerates are
referred to
as macro-agglomerates because they result from the consolidation of both fine
particles and
coarse particles that make up oil sand.
[0007]
U.S. Patent No. 4,719,008 (Sparks et al.) describes a process to apply SESA to
varying ore grade qualities by a micro-agglomeration procedure in which the
fine particles of
the oil sand are consolidated to produce micro-agglomerates with a similar
particle size
distribution to coarser grained particles of the oil sand. Using the micro-
agglomeration
procedure, the solid-liquid separation behavior of the agglomerated oil sand
will be similar
regardless of ore grade quality. The micro-agglomeration procedure occurs
within a slowly
rotating horizontal vessel. The conditions of the slowly rotating horizontal
vessel are that
which favor the formation of large agglomerates; however, a light milling
action is used to
continuously break down the micro-agglomerates. The micro-agglomerates are
formed by
obtaining an eventual equilibrium between cohesive and destructive forces.
Since
micro-agglomerates of large size can lead to bitumen recovery losses owing to
entrapment of
extracted bitumen within the agglomerated solids, the levels of bridging
liquid is kept to as
low as possible commensurate with achieving economically viable solid-liquid
separations.
[0008]
With the formation of the micro-agglomerates, the process of solid-liquid
separation using common separation devices is easier compared to the situation
where the fine
particles are un-agglomerated. Applicable separation devices include at least
one of gravity
separators, centrifuges, hydrocyclones, screens, and filters. Although the
separation devices
have been shown to be effective in separating micro-agglomerates from bitumen
extract, a
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portion of the fine solids remain un-agglomerated because they are non-wetting
with the
aqueous bridging liquid and thus remain as residual fine solids in the bitumen
extract. The
amount of the residual fine solids that remain in the bitumen extract can be
greater than 1 wt.
% on a dry bitumen basis. "Dry bitumen basis" means ignoring the presence of
water in the
bitumen extract for the purpose of calculating wt. %.
[0009] Solvent deasphalting has previously been proposed as a method to
remove the
residual fine solids that remain from the bitumen extract. U.S. Patent No.
4,888,108
(Farnand) describes a process where an aliphatic solvent, such as pentane, is
added along with
a chemical additive to the bitumen extract. The addition of the aliphatic
solvent causes
asphaltenes to precipitate onto the residual fine solids. The combination of
the precipitated
asphaltenes and the chemical additive causes the residual fine solids to
aggregate so that they
can be readily separated from the bitumen extract. Farnand describes that the
most effective
chemical additives are water-soluble organic compounds with a low miscibility
with the
bitumen extract. The organic compounds preferably comprise a carboxylic acid
and/or
hydroxyl groups, and have a weakly acidic and/or polar character. The chemical
additives,
such as resorcinol, catechol, formic acid, and maleic acid, have a synergistic
effect with the
addition of the aliphatic solvent. Less additive and aliphatic solvent was
needed, when used
in combination, to obtain the same level of solids removal as compared to when
the additive
or aliphatic solvent was used alone. Farnand theorized that the improved
residual fine solids
aggregation was due to the precipitated asphaltenes increased attraction to
the residual fine
solids with the polar additives adsorbed onto the residual fine solids
surfaces.
[00101 Another method for removing the residual fine solids that remain
in the
bitumen extract is to use aliphatic solvents for the extraction of bitumen
from oil sand. U.S.
Patent Publication 2011/0127197 (Blackbourn et al.) describes the use of a C3
to C9
paraffinic solvent for extracting bitumen from oil sand. The use of paraffinic
solvent, such as
pentane, prevents all or a portion of the asphaltenes within the bitumen from
dissolving into
solution during the solvent-based recovery process. Since the asphaltenes tend
to be
associated with fine solids, the asphaltenes that do not dissolve prevent the
fine solids from
dispersing into the bitumen extract. Blackbourn et al. described that the use
of the paraffinic
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solvent improved the separation of bitumen extract by filtration. The
increased filtration rate,
compared to when an aromatic solvent was used for bitumen extraction, was most
likely due
to the fact that some of the fine solids remained attached to the solid
asphaltenes and thus
were not free to block the filter media or the solid bed on top of the filter
media. The use of
paraffinic solvent in the solvent-based recovery process resulted in faster
settling fine solids
that could be readily separated from the majority of the bitumen extract by
gravity to produce
a bitumen extract with fine solids content of less than 0.1 wt.% on a dry
bitumen basis.
100111 The use of aliphatic solvents in a solvent-based recovery process
has been
proposed as a method to reduce the amount of residual solvent in tailings.
U.S. Patent No.
8,257,580 (Duyvesteyn et al.) describes a method for preparing dry, stackable
tailings. Dry,
stackable tailings may be defined as comprising less than 0.1 wt.% solvent and
from about 2
wt. % to about 15 wt. %. Water. The method involves contacting the oils sand
with a light
aromatic solvent to dissolve bitumen. The bitumen extract is then separated
from the solids in
order to produce a first solid tailings that has residual bitumen extract
entrained within. The
residual bitumen extract is removed from the tailings by washing the solids
with a light
hydrocarbon solvent to produce solvent-wet tailings where the remaining light
hydrocarbon
solvent can be readily recovered by heating and/or pressure reduction. A light
hydrocarbon
solvent may be defined as a cyclo- or iso-paraffin having between 3 and 9
carbons. The light
hydrocarbon solvent is typically an aliphatic solvent such as at least one of
propane, butane,
and pentane. Duyvesteyn et at. describes that this method has the potential
advantage of
reducing the required energy to recover the light hydrocarbon solvent from
tailings and the
potential advantage of requiring that only the washing stage needs to be
pressurized in the
solvent-based recovery process.
[0012] The above-described processes demonstrate that the use of
aliphatic solvent in
a solvent-based recovery process may reduce the amount of residual solvent in
the tailings.
However, the use of aliphatic solvent does pose challenges to the solvent-
based recovery
process. The use of aliphatic solvent may increase the chance that
asphaltenes, which have
not dissolved (i.e., undissolved asphaltenes), will be present in undesirable
locations within
the solvent-based recovery process. For example, undissolved asphaltenes may
be present in
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an extraction vessel, thereby trapping bitumen within the asphaltene and
inorganic solid
pores. Undissolved asphaltenes may be referred to as precipitated asphaltenes.
The
extraction vessel is a vessel where bitumen is extracted from oil sand. The
bitumen trapped
may result in additional losses of bitumen with the tailings. The undissolved
asphaltenes tend
to foul various components, such as piping, valves, and filters, which may
result in an
increased need for maintenance.
[0013] In view of the aforementioned disadvantages, there is a need for
improved
methods for processing a bituminous feed. For example, there is a need for a
method for
using aliphatic solvents in a solvent-based recovery process that takes
advantage of the
benefits of using aliphatic solvents while mitigating the problems that the
presence of
undissolved asphaltenes may have on the solvent-based recovery process.
SUMMARY
[0014] It is an object of the present disclosure to provide methods for
processing a
bituminous feed.
[0015] A method for processing a bituminous feed may comprise: a) forming
an oil
sand slurry, comprising a bitumen extract and solids, by contacting the
bituminous feed with a
first extraction liquor, comprising a first solvent; b) forming a rich bitumen
extract stream and
separated solids by separating the solids from the bitumen extract; c) forming
a washed solids
stream and a lean bitumen extract stream, comprising precipitated asphaltenes,
by washing the
separated solids with an aliphatic solvent; d) forming a deasphalted lean
bitumen extract
stream by separating the precipitated asphaltenes from the lean bitumen
extract stream; and e)
obtaining a bitumen product stream by removing the first solvent from at least
one of a first
portion of the rich bitumen extract stream and a first portion of the
deasphalted lean bitumen
extract stream.
[0016] A method for processing a bituminous feed may comprise: a) forming
an oil
sand slurry, comprising a bitumen extract and solids, by contacting the
bituminous feed with a
first extraction liquor comprising a first solvent; b) forming a rich bitumen
extract stream,
comprising the bitumen extract and residual fine solids, by separating the
solids from the
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bitumen extract; c) providing a hydrocarbon fluid comprising undissolved
asphaltenes; d)
forming an asphaltene-bitumen extract mixture by mixing the hydrocarbon fluid
with the rich
bitumen extract stream; e) forming a low solids bitumen extract stream by
separating
asphaltenes and the residual fine solids from the asphaltene-bitumen extract
mixture; and f)
obtaining a bitumen product stream by removing the first solvent from the low
solids bitumen
extract stream.
100171 A method for processing a bituminous feed may comprise: a)
providing a first
extraction liquor comprising deasphalted bitumen and a first solvent; b)
forming an oil sand
slurry, comprising a bitumen extract and solids, by contacting the bituminous
feed with the
first extraction liquor; c) forming a rich bitumen extract stream by
separating the solids from
the bitumen extract; and d) obtaining a bitumen product stream by removing the
first solvent
from a first portion of the rich bitumen extract stream.
[0018] The foregoing has broadly outlined the features of the present
disclosure so
that the detailed description that follows may be better understood.
Additional features will
also be described herein.
BRIEF DESCRIPTION OF THE DRAWINGS
[0019] These and other features, aspects and advantages of the disclosure
will become
apparent from the following description, appending claims and the accompanying
drawings,
which are briefly described below.
100201 Figure 1 is a flow chart of a method for processing a bituminous
feed.
[0021] Figure 2 is a flow chart of a method for processing a bituminous
feed.
[0022] Figure 3 is a flow chart of a method for processing a bituminous
feed.
[0023] Figure 4 is a flow chart of a method for processing a bituminous
feed.
[0024] Figure 5 is a flow chart of a method for processing a bituminous
feed.
[0025] Figure 6 is a flow chart of a method for processing a bituminous
feed.
[0026] Figure 7 is a flow chart of a method for processing a bituminous
feed.
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[0027] Figure 8 is a flow chart of a method for processing a bituminous
feed.
[0028] Figure 9 is a flow chart of a method for processing a bituminous
feed.
[0029] It should be noted that the figures are merely examples and no
limitations on
the scope of the present disclosure are intended thereby. Further, the figures
are generally not
drawn to scale, but are drafted for purposes of convenience and clarity in
illustrating various
aspects of the disclosure.
DETAILED DESCRIPTION
[0030] For the purpose of promoting an understanding of the principles of
the
disclosure, reference will now be made to the features illustrated in the
drawings and specific
language will be used to describe the same. It will nevertheless be understood
that no
limitation of the scope of the disclosure is thereby intended. Any alterations
and further
modifications, and any further applications of the principles of the
disclosure as described
herein are contemplated as would normally occur to one skilled in the art to
which the
disclosure relates. It will be apparent to those skilled in the relevant art
that some features
that are not relevant to the present disclosure may not be shown in the
drawings for the sake
of clarity.
[0031] At the outset, for ease of reference, certain terms used in this
application and
their meaning as used in this context are set forth below. To the extent a
term used herein is
not defined below, it should be given the broadest definition persons in the
pertinent art have
given that term as reflected in at least one printed publication or issued
patent. Further, the
present processes are not limited by the usage of the terms shown below, as
all equivalents,
synonyms, new developments and terms or processes that serve the same or a
similar purpose
are considered to be within the scope of the present disclosure.
[0032] Throughout this disclosure, where a range is used, any number
between or
inclusive of the range is implied.
[0033] A "hydrocarbon" is an organic compound that primarily includes the
elements
of hydrogen and carbon, although nitrogen, sulfur, oxygen, metals, or any
number of other
elements may be present in small amounts. Hydrocarbons generally refer to
components
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found in heavy oil or in oil sand. However, the techniques described are not
limited to heavy
oils but may also be used with any number of other reservoirs to improve
gravity drainage of
liquids. Hydrocarbon compounds may be aliphatic or aromatic, and may be
straight chained,
branched, or partially or fully cyclic.
[0034] "Bitumen" is a naturally occurring heavy oil material. Generally,
it is the
hydrocarbon component found in oil sand. Bitumen can vary in composition
depending upon
the degree of loss of more volatile components. It can vary from a very
viscous, tar-like,
semi-solid material to solid forms. The hydrocarbon types found in bitumen can
include
aliphatics, aromatics, resins, and asphaltenes. A typical bitumen might be
composed of:
19 weight (wt.) % aliphatics (which can range from 5 wt. % - 30 wt. %, or
higher);
19 wt. % asphaltenes (which can range from 5 wt. % - 30 wt. %, or higher);
30 wt. % aromatics (which can range from 15 wt. % - 50 wt. %, or higher);
32 wt. % resins (which can range from 15 wt. % - 50 wt. %, or higher); and
some amount of sulfur (which can range in excess of 7 wt. %).
In addition, bitumen can contain some water and nitrogen compounds ranging
from less than
0.4 wt. % to in excess of 0.7 wt. %. The percentage of the hydrocarbon found
in bitumen can
vary. The term "heavy oil" includes bitumen as well as lighter materials that
may be found in
a sand or carbonate reservoir.
[0035] "Heavy oil" includes oils which are classified by the American
Petroleum
Institute ("API"), as heavy oils, extra heavy oils, or bitumens. The term
"heavy oil" includes
bitumen. Heavy oil may have a viscosity of about 1,000 centipoise (cP) or
more, 10,000 cP or
more, 100,000 cP or more, or 1,000,000 cP or more. In general, a heavy oil has
an API
gravity between 22.3 API (density of 920 kilograms per meter cubed (kg/m3) or
0.920 grams
per centimeter cubed (g/cm3)) and 10.0 API (density of 1,000 kg/m3 or 1
g/cm3). An extra
heavy oil, in general, has an API gravity of less than 10.0 API (density
greater than 1,000
kg/m3 or 1 g/cm3). For example, a source of heavy oil includes oil sand or
bituminous sand,
which is a combination of clay, sand, water and bitumen. The recovery of heavy
oils is based
on the viscosity decrease of fluids with increasing temperature or solvent
concentration. Once
the viscosity is reduced, the mobilization of fluid by steam, hot water
flooding, or gravity is
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possible. The reduced viscosity makes the drainage or dissolution quicker and
therefore
directly contributes to the recovery rate.
[0036] The term "bituminous feed" refers to a stream derived from oil
sand 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.
Undesirable components may include but are not limited to clay, minerals,
coal, debris and
water. The bituminous feed may be derived directly from oil sand, and may be,
for example,
raw oil sand 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
sand, 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.
[0037] "Fine particles" are generally defined as those solids having a
size of less than
44 microns (um), that is, material that passes through a 325 mesh (44 micron).
[0038] "Coarse particles" are generally defined as those solids having a
size of greater
than 44 microns (um).
[0039] A "solvent-based recovery process" or "solvent extraction process"
or "oil
sand solvent extraction process" includes any type of hydrocarbon recovery
process that uses
a solvent, at least in part, to enhance the recovery, for example, by diluting
or lowering a
viscosity of the hydrocarbon. Solvent-based recovery processes may be used in
combination
with other recovery processes, such as, for example, thermal recovery
processes. In solvent-
based recovery processes, a solvent is injected into a subterranean reservoir.
The solvent may
be heated or unheated prior to injection, may be a vapor or liquid and may be
injected with or
without steam. Solvent-based recovery processes may include, but are not
limited to, solvent
assisted cyclic steam stimulation (SA-CSS), solvent assisted steam assisted
gravity drainage
(SA-SAGD), solvent assisted steam flood (SA-SF), vapor extraction process
(VAPEX),
heated vapor extraction process (H-VAPEX), cyclic solvent process (CSP),
heated cyclic
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solvent process (H-CSP), solvent flooding, heated solvent flooding, liquid
extraction process,
heated liquid extraction process, solvent-based extraction recovery process
(SEP), thermal
solvent-based extraction recovery processes (TSEP), and any other such
recovery process
employing solvents either alone or in combination with steam. A solvent-based
recovery
process may be a TSEP if the solvent is heated prior to injection into the
subterranean
reservoir. The solvent-based recovery process may employ gravity drainage.
[0040] "Macro-agglomeration" is the consolidation of both fine particles
and coarse
particles that make up the oil sand. Macro-agglomerates may have a mean
diameter of 2
millimeters (mm) or greater.
[0041] "Micro-agglomeration" is the consolidation of fine particles that
make up the
oil sand. Micro-agglomerates may have a mean diameter of less than 2
millimeters (mm).
[0042] A "rich bitumen extract stream" is generally defined as a bitumen
extract
stream from which at least some solids have been removed.
[0043] A "lean bitumen extract stream" is generally defined as a bitumen
extract
stream from which a rich bitumen stream and at least some solids have been
removed.
[0044] A "washed solids stream" is generally defined as a solids stream
that has been
washed using a solvent, such as but not limited to an aliphatic solvent.
[0045] A "deasphalted lean bitumen extract stream" is generally defined
as a lean
bitumen extract stream that has been deasphalted to remove some or all
asphaltenes.
[0046] A "bitumen extract" is generally defined as bitumen that has been
extracted
from oil sand.
[0047] "Residual solid fines" are generally defined as fines remaining in
a stream
following a solids separation process.
[0048] A "bitumen product stream" is generally defined as a high grade
bitumen
product that may be suitable for transport within pipelines and processing
within downstream
refineries. A high grade bitumen product stream may have a solids content of
less than 1
wt.%, or less than 0.1 wt. %, on a dry bitumen basis.
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[0049] A "low grade bitumen product stream" is generally defined as the
result of
removing solvent from a stream containing precipitated asphaltenes, such as
precipitated
asphaltenes which have been removed from a lean bitumen extract stream, or an
asphaltene-
bitumen extract mixture comprising precipitated asphaltenes, or a precipitated
asphaltenes
separated from a diluted bitumen extract stream.
[0050] The term "solvent" as used in the present disclosure should be
understood to
mean either a single solvent, or a combination of solvents.
[0051] "Solvent deasphalting" is generally defined as a method to remove
the solids
that remain in a bitumen extract from the bitumen extract.
[0052] The terms "approximately," "about," "substantially," and similar
terms are
intended to have a broad meaning in harmony with the common and accepted usage
by those
of ordinary skill in the art to which the subject matter of this disclosure
pertains. It should be
understood by those of skill in the art who review this disclosure that these
terms are intended
to allow a description of certain features described and claimed without
restricting the scope
of these features to the precise numeral ranges provided. Accordingly, these
terms should be
interpreted as indicating that insubstantial or inconsequential modifications
or alterations of
the subject matter described and are considered to be within the scope of the
disclosure.
[0053] The articles "the", "a" and "an" are not necessarily limited to
mean only one,
but rather are inclusive and open ended so as to include, optionally, multiple
such elements.
[0054] "At least one," in reference to a list of one or more entities
should be
understood to mean at least one entity selected from any one or more of the
entity in the list of
entities, but not necessarily including at least one of each and every entity
specifically listed
within the list of entities and not excluding any combinations of entities in
the list of entities.
This definition also allows that entities may optionally be present other than
the entities
specifically identified within the list of entities to which the phrase "at
least one" refers,
whether related or unrelated to those entities specifically identified. Thus,
as a non-limiting
example, "at least one of A and B" (or, equivalently, "at least one of A or
B," or, equivalently
"at least one of A and/or B") may refer, to at least one, optionally including
more than one, A,
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with no B present (and optionally including entities other than B); to at
least one, optionally
including more than one, B, with no A present (and optionally including
entities other than
A); to at least one, optionally including more than one, A, and at least one,
optionally
including more than one, B (and optionally including other entities). In other
words, the
phrases "at least one," "one or more," and "and/or" are open-ended expressions
that are both
conjunctive and disjunctive in operation. For example, each of the expressions
"at least one
of A, B and C," "at least one of A, B, or C," "one or more of A, B, and C,"
"one or more of A,
B, or C" and "A, B, and/or C" may mean A alone, B alone, C alone, A and B
together, A and
C together, B and C together, A, B and C together, and optionally any of the
above in
combination with at least one other entity.
100551
Solvent deasphalting of a lean bitumen extract stream has the advantage of
controlling a location within a solvent extraction process where asphaltenes
are precipitated.
It may be desirable to limit or eliminate asphaltene precipitation within
transfer lines carrying
asphaltene containing streams between equipment used in a solvent extraction
process to
mitigate fouling. It may desirable to limit the amount of undissolved
asphaltenes within an
extraction vessel of a solvent extraction process to limit the effect
undissolved asphaltenes
have on reducing the rate by which bitumen dissolves into an extraction
liquor. There are
locations within the solvent extraction process where asphaltene precipitation
may be
desirable. For example, asphaltene precipitation may be desirable in locations
within the
solvent extraction process where the lean bitumen extract stream is mixed with
a rich bitumen
extract stream to form a combined stream. The combined stream may be
deasphalted to
produce a deasphalted bitumen extract stream and a deasphalted extraction
liquor. The
deasphalted bitumen extract stream has the advantage that residual solid fines
are removed
during deasphalting to produce reduced ash and increased API bitumen product,
as compared
to a bitumen extract stream that has not been deasphalted, when solvent is
removed from the
deasphalted bitumen extract. The deasphalted extraction liquor may have the
advantage of
producing an extraction liquor that more readily extracts bitumen from the
bituminous feed
than an extraction liquor that is not deasphalted. The deasphalted extraction
liquor may have
this advantage because of the absence of asphaltene molecules within the
extraction liquor.
The asphaltene molecules may reduce the rate of bitumen dissolution.
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CA 02867357 2014-10-16
[0056]
The solvent deasphalting described in the present disclosure may be referred
to
as controlled deasphalting. The controlled deasphalting may be combined with
aspects of
other solvent extraction processes, including but not limited to solvent
extraction with a solids
agglomeration process. Non-limiting examples of solvent extraction processes
that are
solvent extraction with solids agglomeration processes, include those
described in the
background of the present disclosure and in CA 2,724,806 ("Adeyinka et al.").
[0057]
Adeyinka et at. discloses extracting bitumen from oil sand in a manner that
employs solvent. A first solvent is combined with a bituminous feed derived
from oil sand to
form an initial slurry. The initial slurry is separated into a fines solids
stream and a coarse
solids stream, where the majority of the fine solids within the oil sand are
in the fine solids
stream and the majority of the coarse solids within oil sand are in the coarse
solids stream.
The coarse solids steam can be separated into coarse solids and a first low
solids bitumen
extract stream. Aqueous bridging liquid is added to the fine solids stream to
agglomerate the
fine solids in the stream and form an agglomerated slurry. The agglomerated
slurry can be
separated into agglomerates and a second low solids bitumen extract stream. A
second
solvent can be mixed with the first and second low solids bitumen extract
streams to form 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 high
grade bitumen
extracts is conducted to produce bitumen products of commercial value.
[0058]
The solvent extraction with solid agglomeration processes described by
Adeyinka et at. is one suitable solvent extraction process for the processes
described in the
present disclosure. The aqueous bridging liquid of Adeyinka et at. may be
added to the slurry
(without separating the slurry into a coarse stream and a fine stream),
followed by
agglomeration. The extraction liquor that contacts the bituminous feed may
allow for
complete or near complete dissolution of the bitumen to increase overall
bitumen recovery.
Complete dissolution of the bitumen will result in fine solids dispersing into
the bitumen
extract which, if left dispersed, will hamper solid-liquid separation
downstream of the
extraction process. In
contrast to the method described in U.S. Patent Publication
2011/0127197 (Blackbourn et al.), the initial dispersing of the fine solids of
Adeyinka et at. is
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acceptable because the solid agglomeration process will allow for the majority
of the fine
solids to be recaptured as agglomerates with the aqueous bridging liquid. The
lean bitumen
extract stream described in the present disclosure may be used as the second
solvent in the
process described by Adeyinka et al. The lean bitumen extract stream, which
may be
comprised of an aliphatic solvent such as but not limited to pentane, when
mixed with the low
solids bitumen extract, may result in asphaltene precipitation. The asphaltene
precipitation
may be referred to as precipitated asphaltenes. The precipitated asphaltenes
aggregate with
the residual solids, forming aggregated precipitated asphaltenes, and settle
by gravity to form
a high grade bitumen extract above a low grade bitumen extract. Solvent within
the high
grade bitumen extract can be recovered from the high grade bitumen extract
overflow to form
a bitumen product with a solid content of less than 0.1 wt. %. The low grade
bitumen extract
may be recycled to other units of the solvent extraction process to separate
bitumen from the
aggregated precipitated asphaltenes. Solvent may be recovered from the low
grade bitumen
extract to produce a low grade bitumen product with commercial value.
[0059] Figure 1 is a flow chart of a method for processing a bituminous
feed. The
method may de-asphalt a lean bitumen extract stream. Figure 5 is another flow
chart for
processing a bituminous feed.
[0060] The method may comprise forming an oil sand slurry (108) by
contacting a
bituminous feed (102) with a first extraction liquor (104), in a bitumen
extraction step (106),
(502). The oil sand slurry (108) may comprise a bitumen extract and solids.
[0061] The first extraction liquor may comprise a first solvent. The
first solvent may
be used to extract bitumen from the bituminous feed. The first extraction
liquor may
comprise a hydrocarbon solvent capable of dissolving the bitumen. The first
extraction liquor
may be a solution of a hydrocarbon solvent(s) and bitumen, where the bitumen
content of the
first extraction liquor may range between 0 and 70 wt.%, or between 0 and 50
wt.%, or
between 30 and 70 wt. %. The first extraction liquor may contain dissolved
bitumen. When
the first extraction liquor contains dissolved bitumen, the volume of the
first extraction liquor
may be increased without an increase in the required inventory of hydrocarbon
solvent(s).
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CA 02867357 2014-10-16
[0062] A second solvent (142) may be added in the bitumen extraction step
(106).
The second solvent (142) may contact the bituminous feed (102) to help form
the oil sand
slurry (108).
[0063] The solvent extraction process may be adjusted to provide a ratio
of solvent
(the first solvent and/or the second solvent) to bitumen in the oil sands
slurry that minimizes
asphaltenes precipitation during the bitumen extraction step (106). The
presence of some
amount of precipitated asphaltenes is unavoidable. By adjusting the amount of
first and/or
second solvent flowing into a bitumen extraction vessel of the bitumen
extraction step (106), a
ratio of the first and/or second solvent to the bitumen in the bitumen
extraction vessel can be
controlled. Bitumen in the bitumen extraction vessel comes from the bituminous
feed and any
bitumen entrained in the first extraction liquor. Selecting the ratio of the
first and/or second
solvent to the bitumen may decrease the costs for processing the bituminous
feed if the ratio is
one with less solvent than bitumen. Having less first and/or second solvent
than bitumen may
lower the costs for processing the bituminous feed because of the lower first
and/or second
solvent requirements.
[0064] The ratio of the first and/or second solvent to the bitumen may be
selected as a
target ratio. The target ratio may be less than 2:1. For example but not
limited to, the target
ratio may be 1.5:1 or less, 1:1 or less, or 0.75:1. For clarity, ratios may be
expressed in the
present disclosure 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.
[0065] The first extraction liquor may be recycled to the bitumen
extraction step (106)
from a downstream step, such as but not limited to from liquid splitter (140),
as detailed
below. Residual bitumen within the first extraction liquor may increase the
volume of the
first extraction liquor. The residual bitumen within the first extraction
liquor may increase the
solubility of the first extraction liquor for additional bitumen dissolution.
[0066] Throughout this application including with reference to all
Figures, the terms
"solvent", "first solvent", "second solvent", and "third solvent" are each
considered to be a
"solvent" as defined in the present disclosure. The "solvent", "first
solvent", "second
- 16 -
CA 02867357 2014-10-16
solvent", and/or "third solvent" may be the same or different from one
another. As is evident
from the description of the Figures, the "solvent", "first solvent", "second
solvent", and/or
"third solvent" may be added in different locations in the process and/or may
be added alone
or as part of a composition such as but not limited to as part of an
extraction liquor (e.g., a
first extraction liquor, a second extraction liquor). The "first solvent",
"second solvent",
and/or "third solvent" may interchangeably be referred to as a solvent. This
paragraph applies
to all of the Figures in the present disclosure.
[0067] Several types of solvents are suitable for use in the solvent
extraction process.
The solvent may comprise an organic solvent or a mixture of organic solvents.
The solvent
may comprise light aromatic compounds. The light aromatic compounds may be a
light
aromatic solvent with zero to 100% aromatic compounds. A light aromatic
solvent may have
less than 16 carbon atoms per molecule. Exemplary solvents include, but are
not limited to,
benzene, toluene, naphtha and kerosene. In cases where the aromatic content of
the solvent is
less than what is needed to fully dissolve the bitumen in the bituminous feed,
pre-dissolved
bitumen within the extraction liquor can increase the solubility of the
extraction liquor
towards dissolving additional bitumen. This paragraph applies to all of the
Figures in the
present disclosure.
[0068] The solvent may comprise at least one of an open chain aliphatic
hydrocarbon,
and a cyclic aliphatic hydrocarbon. Low boiling point cycloalkanes, or mixture
of such
cycloalkanes, can substantially dissolve asphaltenes. This paragraph applies
to all of the
Figures in the present disclosure.
[0069] The solvent may comprise a paraffinic solvent. The paraffinic
solvent may be
one in which the solvent to bitumen ratio of the bitumen extract and/or the
first extraction
liquor is maintained at a level to avoid or limit precipitation of
asphaltenes. The paraffinic
solvent may comprise at least one of an alkane, a natural gas condensate, and
a distillate from
a fractionation unit (or diluent cut) containing more than 40% small chain
paraffins of 3 to 10
carbon atoms, referred to in the present disclosure as a small chain (or short
chain) paraffin
mixture. This paragraph applies to all of the Figures in the present
disclosure.
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[0070] Should an alkane be selected as the solvent, the alkane may
comprise at least
one of a normal alkane and an iso-alkane. The alkane may comprise at least one
of heptane,
iso-heptane, hexane, iso-hexane, pentane, and iso-pentane. This paragraph
applies to all of
the Figures in the present disclosure.
[0071] A cyclic aliphatic hydrocarbon may be selected as the solvent, it
may comprise
a cycloalkane of 4 to 9 carbon atoms. A mixture of C3-C9 cyclic and/or open
chain aliphatic
solvents may be appropriate. Exemplary cycloalkanes include at least one of
cyclohexane and
cyclopentane. 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 C. An exemplary
upper limit of
the final boiling point of the distillate may be less than 100 C. A mixture of
C3-C10 cyclic
and/or open chain aliphatic solvents would also be appropriate. For example,
it can be a
mixture of C3-C9 cyclic aliphatic hydrocarbons and paraffinic solvents where
the percentage
of the cyclic aliphatic hydrocarbons in the mixture is greater than 50%. This
paragraph
applies to all of the Figures in the present disclosure.
[0072] The solvent may have a final boiling point of less than 200 C
(degrees
Celsius). The solvent may have a final boiling point of less than 100 C. While
it is not
necessary to use a solvent having a boiling point of less than 200 C or less
than 100 C, there
may be an extra advantage that solvent recovery proceeds at lower
temperatures, and requires
a lower energy consumption than solvent recovery at higher temperatures.
[0073] The oil sand slurry may have a solid content in the range of 5 to
70 wt.%, 20 to
70 wt.%, or 40 to 70 wt.%. In the case of a solvent extraction process with
solids
agglomeration process, a higher solids content oil sand slurry may be desired.
The higher
solids content may increase the compaction forces that may help in the solids
agglomeration
process. In other cases, a lower solids content may be desired. The lower
solids content may
reduce the mixing energy needed in the solvent based extraction process. The
oil sand slurry
may have a higher solids content for the extraction and agglomeration
processes and then be
diluted to a lower solids content prior to solid-liquid separation. This
paragraph applies to all
of the Figures in the present disclosure.
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[0074] The temperature of the oil sand slurry may be at a value that is
configured to
minimize a presence of undissolved asphaltenes in the oil sand slurry. The
value may include
any number within or bounded by the range of 20-100 C. When the temperature of
the oil
sand slurry is kept at a value that minimizes the presence of undissolved
asphaltenes in the oil
sand slurry, the bitumen dissolution rate may be decreased; the viscosity of
the oil sand slurry
may be decreased. Decreasing the bitumen dissolution rate and/or the viscosity
of the oil sand
slurry may promote more effective sand digestion and agglomerate formation
than increasing
the bitumen dissolution rate and/or decreasing the viscosity of the oil sand
slurry. When the
temperature of the oil sand slurry is kept at the value that minimizes the
presence of
undissolved asphaltenes in the oil sand slurry, the solid-liquid separation
may be improved
because higher temperatures may result in a reduced slurry viscosity, which in
turn, may
improve the solid-liquid separation process. Temperatures above 100 C are
generally
avoided due to the complications resulting from high vapor pressures. This
paragraph applies
to all Figures in the present disclosure.
[0075] The method may comprise diluting the oil sand slurry (108) prior
to separating
the solids in the oil sand slurry (108) from the bitumen extract in the oil
sand slurry (108).
The oil sand slurry (108) may be diluted in a dilution step (110) to form a
diluted oil sand
slurry (147). The oil sand slurry (108) may be diluted by a second extraction
liquor (112).
The oil sand slurry (108) may be diluted by a third solvent (144). The first
extraction liquor
(104) may have a bitumen content that is the same or more than that of the
second extraction
liquor (112). The bitumen content of the second extraction liquor (112) may be
between 0 and
70 wt. %.
[0076] The method may comprise forming a rich bitumen extract stream
(118) and
separated solids (116) by separating the solids from the bitumen extract,
(504). The method
may comprise forming the rich bitumen extract stream (118) and the separated
solids (116) in
a solid-liquid separator (114). Any suitable solid-liquid separator (114) may
be used. For
example and without limitation, the solid-liquid separator (114) may comprise
a gravity settler
or an enhanced gravity settler.
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[0077] The method may comprise forming a washed solids stream (124) and a
lean
bitumen extract stream (126) by washing the separated solids (116) with an
aliphatic solvent
(122), (506). The separated solids (116) may be washed with the aliphatic
solvent (122) in a
washer unit (120). The aliphatic solvent (122) may be used to precipitate
asphaltenes, which
are removed from the washer unit (120) as part of the lean bitumen extract
stream (126). The
lean bitumen extract stream (122) may comprise precipitated asphaltenes.
[0078] The method may comprise forming a deasphalted lean bitumen extract
stream
(132) by separating the precipitated asphaltenes (130) from the lean bitumen
extract stream
(126), (508). The precipitated asphaltenes (130) may be separated from the
lean bitumen
extract stream (126) in a separator (128). The separator (128) may be any
suitable separator.
For example, the separator (128) may include but is not limited to a gravity
settler or an
enhanced gravity settler. At least a portion of the deasphalted lean bitumen
extract stream
(132) may be recycled as recycled deasphalted lean bitumen extract stream. The
recycled
deasphalted lean bitumen extract stream may be the second extraction liquor
(112). The
recycled deasphalted lean bitumen extract stream may be the first extraction
liquor (104).
Solvent may be recovered from the precipitated asphaltenes (130) to form a low
grade
bitumen stream (not shown).
[0079] The method may comprise recycling at least a portion of the rich
bitumen
extract stream (118) as recycled rich bitumen extract stream. The recycled
rich bitumen
extract stream may be the first extraction liquor (104). The rich bitumen
extraction extract
stream (118) may be fed to a liquid splitter (140) to split the rich bitumen
extract stream (118)
into a first portion of the rich bitumen extract stream (148) and a second
portion of the rich
bitumen extract stream (104). The second portion of the rich bitumen extract
stream (104)
may be the at least the portion of the rich bitumen extract stream recycled as
the recycled rich
bitumen extract stream. The first portion of the rich bitumen extract stream
(148) may be
referred to as a portion of the rich bitumen extract stream. The second
portion of the rich
bitumen extract stream 104 may be referred to as a portion of the rich bitumen
extract stream.
Using at least a portion of the rich bitumen extract stream as the first
extraction liquor may
ensure that the solvent-to-bitumen ratio (S:B) of the initial bitumen extract
obtained from
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CA 02867357 2014-10-16
dissolution of bitumen from the bituminous feed is less than the S:B of the
lean bitumen
extract. The lower S:B ratio has the advantage of increasing the amount of
bitumen
dissolution from the bituminous feed, which may increase overall bitumen
recovery.
Additional solvent may be added to the recycled rich bitumen extract stream to
achieve a
desired S:B ratio.
[0080] The method may comprise obtaining a bitumen product stream (138)
by
removing the first solvent (136) from at least one of a portion (148) of the
rich bitumen
extract stream (118) (i.e., the first portion of the rich bitumen extract
stream (148)) and a
portion (149) of the deasphalted lean bitumen extract stream (132), (510). The
bitumen
product stream (138) may be obtained by removing solvent in a solvent recovery
step (134)
from at least one of the portion (148) of the rich bitumen extract stream
(118) and a portion of
the deasphalted lean bitumen extract stream (132). The portion (148) of the
rich bitumen
extract stream (118) may be referred to as the first portion of the rich
bitumen extract stream;
the portion (149) of the deasphalted lean bitumen extract stream may be
referred to as the first
portion of the deasphalted lean bitumen extract stream, or the second portion
of the
deasphalted lean bitumen extract stream.
[0081] The method may comprise mixing an additional solvent with the
recycled
deasphalted lean bitumen extract stream. The method may comprise mixing the
additional
solvent prior to the recycled deasphalted lean bitumen extract stream's use as
the first
extraction liquor (104) and/or the second extraction liquor (112). The first
extraction liquor
and/or the second extraction liquor (112) may comprise, in addition to the
deasphalted lean
bitumen extract stream (132), the additional solvent.
[0082] The deasphalting of the lean bitumen extract stream, of the
process depicted in
Figure 1, has the advantage of controlling the location within the solvent
extraction process
where asphaltenes are precipitated. The precipitated asphaltenes and fine
solids may be
separated from the lean bitumen extract stream in the separator (128). The
deasphalted lean
bitumen extract stream (132) may reduce the chance that asphaltene
precipitation will foul
process equipment, including but not limited to the pipelines used to recycle
the lean bitumen
extract stream (126) to upstream processes. Reducing the risk of fouling
process equipment
- 21 -
CA 02867357 2014-10-16
by asphaltene precipitation may substantially decrease the need for
maintenance of the
process equipment. The lower solid content of the deasphalted lean bitumen
extract stream
(132) may reduce the chance of plugging of process equipment by solids. For
this reason, the
hydrodynamic requirements for fluid flow in pipelines and other process
equipment may be
dictated by factors other than the risk of solid settling.
[0083] The method may comprise forming an asphaltene-bitumen extract
mixture by
mixing the precipitated asphaltenes (130) with at least some of the portion of
the rich bitumen
extract stream (148) (not shown). The asphaltene-bitumen extract mixture may
be separated
from the first portion of the rich bitumen extract stream (148) to remove the
residual solids
that are within the first portion of the rich bitumen extract stream (148).
Removing the
residual solids may allow for the precipitated asphaltenes (130) from the lean
bitumen extract
stream (126) to assist with the aggregation and separation of the residual
fine solids from the
first portion of the rich bitumen extract stream (148).
[0084] The temperature and pressure of the asphaltene-bitumen extract
mixture can be
adjusted to improve the ability of the precipitated asphaltenes (130) to
aggregate the fine
solids. For example, the asphaltene-bitumen extract mixture temperature may be
lowered
(i.e., the asphaltene-bitumen extract mixture temperature may be cooled) to
increase the
viscosity and capture ability of the precipitated asphaltenes (130) and/or to
reduce the
tendency of the precipitated asphaltenes to dissolve; the asphaltene-bitumen
extract mixture
temperature may be increased (i.e., the asphaltene-bitumen extract mixture may
be heated) to
reduce the tendency of the precipitated asphaltenes to dissolve based on their
thermodynamic
equilibrium. Additional aliphatic solvent, such as but not limited to pentane,
may be added to
the asphaltene-bitumen extract mixture to precipitate additional asphaltenes
that may further
help aggregate the fine solids. Solvent may be removed from the asphaltene-
bitumen extract
mixture to obtain a low grade bitumen product stream.
[0085] Prior to entering the dilution step (110), the oil sand slurry may
be mixed with
an aqueous bridging liquid to form an agglomerated slurry. Mixing the oil sand
slurry with
the aqueous bridging liquid may help to agglomerate the solids within the oil
sand slurry and
form an agglomerated slurry. The agglomerates within the agglomerated slurry
may be sized
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on the order of 0.1-1.0 mm, on the order of 0.1-0.5 mm or on the order of 0.1-
0.3 mm. At
least 80 wt. % of the agglomerates within the agglomerated slurry may be 0.1-
1.0 mm, on the
order of 0.1-0.5 mm or 0.1 to 0.3 mm in size. The rate of agglomeration may be
controlled by
a balance between intensity of agitation within an agglomeration vessel, shear
within the
vessel which can be adjusted, for example, by changing the shape or size of
the vessel, fines
content of the slurry, bridging liquid addition, and residence time of the
agglomeration
process. The agglomerated slurry may have a solids content of 20 to 70 wt. %.
[0086] The aqueous bridging liquid may be a liquid with affinity for the
solids
particles in the bituminous feed. The aqueous bridging liquid may be a liquid
that is
immiscible in the first extraction liquor and/or the second extraction liquor.
Exemplary
aqueous bridging liquids may be water that accompany the bituminous feed
and/or recycled
water from other aspects or steps of oil sand processing. The aqueous bridging
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 solution with a range of pH, or any other acceptable aqueous solution
capable of
adhering to solid particles in such a way that permits fines to adhere to each
other. An
exemplary aqueous bridging liquid is water. The aqueous bridging liquid may be
added to the
slurry in a concentration of less than 20 wt. % of the slurry, less than 10
wt. % of the slurry,
between 1 wt. % and 20 wt. %, or between 1 wt. % and 10 wt. %. The aqueous
bridging
liquid may comprise fine particles (for instance less than 44 micrometer
(,tm)) suspended
within the aqueous bridging liquid. The fine particles suspended may serve as
seed particles
for the agglomeration process. The aqueous bridging liquid may comprise less
than 40 wt.%
solid fines, or have a solids content of 20 to 70 wt. %.
[0087] The agglomeration process may be assisted by some form of
agitation. The
form of agitation may be mixing, shaking, rolling, or another known suitable
method. The
agitation of the bituminous feed (102) need only be severe enough and of
sufficient duration
to intimately contact the aqueous bridging liquid with the solids in the
bituminous 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
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vessels, a sufficient amount of agitation is needed to keep the formed
agglomerates in
suspension. In rolling type vessels, the solids content of the bituminous feed
may be greater
than 40 wt. % so that compaction forces assist agglomerate formation. The
agitation of the oil
sand slurry has an impact on the growth of the agglomerates. In the case of
mixing type
vessels, the mixing power can be increased in order to limit the growth of
agglomerates by
attrition of said agglomerates. In the case of rolling type vessels the fill
volume and rotation
rate of the vessel can be adjusted in order to increase the compaction forces
used in the
communition of agglomerates.
[0088] Figure 2 is a flow chart of a method for processing a bituminous
feed. The
method shown in Figure 2 may de-asphalt a diluted bitumen product stream.
[0089] The method may comprise forming an oil sand slurry (208) by
contacting a
bituminous feed (202) with a first extraction liquor (204) in a bitumen
extraction step (206),
(502). The oil sand slurry (208) may comprise a bitumen extract and solids.
The first
extraction liquor (204) may be comprised of the same components as the first
extraction
liquor (104) previously described. A second solvent (242) may be added in the
bitumen
extraction step (206). The second solvent (242) may contact the bituminous
feed (202) to
help form the oil sand slurry (208).
[0090] The method may comprise diluting the oil sand slurry (208) prior
to separating
the solids in the oil sand slurry (208) from the bitumen extract in the oil
sand slurry (208).
The oil sand slurry (208) may be diluted in a dilution step (210) to form a
diluted oil sand
slurry (247). The oil sand slurry (208) may be diluted by a second extraction
liquor (207).
The oil sand slurry (208) may be diluted by a third solvent (244). The first
extraction liquor
(204) may have a bitumen content that is the same or more than that of the
second extraction
liquor (207) as described above with reference to Figure 1.
[0091] The method may comprise forming a rich bitumen extract stream
(218) and
separated solids (216) by separating the solids from the bitumen extract (504)
in a separation
step (214) as described above with reference to Figure 1.
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[0092] The method may comprise forming a washed solids stream (224) and a
lean
bitumen extract stream (226) by washing the separated solids (216) with an
aliphatic solvent
(222), (508). The separated solids (216) may be washed with the aliphatic
solvent (222) in a
washer unit (220). The aliphatic solvent (222) may be used to precipitate
asphaltenes which
are removed from the washer unit (220) as part of the lean bitumen extract
stream (226) as
described above with reference to Figure 1. The lean bitumen extract stream
(226) may
comprise precipitated asphaltenes.
[0093] The method may comprise forming a diluted bitumen extract stream
(not
shown) by combining a portion of the rich bitumen extract stream (219) with a
portion of the
lean bitumen extract stream (226) in a deasphalting unit (228). The method may
comprise
forming the portion of the rich bitumen extract stream (219) that contacts the
portion of the
lean bitumen extract stream (226) to form the deasphalted bitumen extract
stream in a liquid
splitter (240). The rich bitumen extract stream (218) may be fed to the liquid
splitter (240).
Once in the liquid splitter (240), the rich bitumen extract stream (218) may
be split into the
portion of the rich bitumen extract stream (219), which contacts the portion
of the lean
bitumen extract stream (226) to form the deasphalted bitumen extract stream,
and a second
portion of the rich bitumen extract stream (204). The second portion of the
rich bitumen
extract stream (204) may be used as the first extraction liquor (204). The
portion of the lean
bitumen extract stream (226) may be mixed with the portion of the rich bitumen
extract
stream (219) to help remove residual fine solids from the portion of the rich
bitumen extract
stream (219). The portion of the rich bitumen extract stream (219) may be
referred to as a
first portion of the rich bitumen extract stream. The second portion of the
rich bitumen
extract stream (204) may be referred to as a portion of the rich bitumen
extract stream.
[0094] The method may comprise forming a deasphalted bitumen extract
stream (231)
by separating precipitated asphaltenes (230) from the diluted bitumen extract
stream in the
deasphalting unit (228).
[0095] The method may comprise obtaining a bitumen product stream (238)
by
removing solvent (236) from the deasphalted bitumen extract stream (231). The
solvent (236)
may be removed from the deasphalted bitumen extract stream (231) in a solvent
recovery unit
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CA 02867357 2014-10-16
(234). The bitumen product stream (238) may have a solids content of less than
1 wt. %, or
less than 0.1 wt. %. Solvent (236) can be removed from the deasphalted bitumen
extract
stream (231) to produce a bitumen product stream (238) with a solids content
low enough to
be for downstream refining operations.
100961 The deasphalting of the diluted bitumen extract stream, of the
process depicted
in Figure 2, has the advantage of controlling the location within the solvent
extraction process
where asphaltenes are precipitated. A majority of the solids that remain
suspended in the rich
bitumen extract stream are oleophilic solids with organic matter adsorbed on
the solids. The
solids suspended in the rich bitumen extract stream may remain suspended
because of strong
interactions with certain components of dissolved bitumen. When an aliphatic
solvent, such
as but not limited to pentane, is mixed with the rich bitumen extract stream,
the solids
suspended tend to aggregate into larger particles that can be readily
separated from the
bitumen extract stream within the rich bitumen extract stream. The solids
suspended may
aggregate with precipitated asphaltenes to form even larger aggregates. The
larger aggregates
may be readily separated from the lean bitumen extract stream in a separator
(214).
[0097] A portion of the lean bitumen extract stream may not be mixed with
the rich
bitumen extract stream. This portion of the lean bitumen extract stream may be
deasphalted
in a fashion similar to what is described in the process of Figure 1 to
produce a deasphalted
lean bitumen extract stream, which can be used as part of the second
extraction liquor (207)
and/or as part of the first extraction liquor (204).
100981 Figure 3 is a flow chart of a method for processing a bituminous
feed. The
method may de-asphalt an extraction liquor and a diluted bitumen product
stream.
[0099] The method may comprise forming an oil sands slurry (308) by
contacting a
bituminous feed (302) with a first extraction liquor (304) comprising a first
solvent in a
bitumen extraction step (306), (602). The oil sands slurry (308) may comprise
a bitumen
extract and solids. The first extraction liquor (304) may be comprised of the
same
components of the first extraction liquor (104) previously described. A second
solvent (342)
may be added in the bitumen extraction step (306). The second solvent (342)
may contact the
bituminous feed (302) to help form the oil sand slurry (308).
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CA 02867357 2014-10-16
[001001 The method may comprise diluting the oil sands slurry (308) prior
to
separating the solids in the oil sands slurry (308) from the bitumen extract
in the oil sands
slurry (308). The oil sands slurry (308) may be diluted in a dilution step
(310) to form a
diluted oil sand slurry (347). The oil sands slurry (308) may be diluted by a
second extraction
liquor (305). The oil sands slurry (308) may be diluted by a third solvent
(344).
[00101] The method may comprise forming a rich bitumen extract stream
(318) and
separated solids (316) by separating the bitumen extract from the solids in a
separation step
(314) as described above with reference to Figure 1, (604). The separated
solids may be
referred to as residual fine solids.
100102] The method may comprise forming a washed solids stream (324) and a
lean
bitumen extract stream (326) by washing the separated solids (316) with an
aliphatic solvent
(322). The separated solids (316) may be washed with the aliphatic solvent
(322) in a washer
unit (320). The aliphatic solvent (322) may be used to precipitate
asphaltenes, which are
removed from the washer unit (320) as part of the lean bitumen extract stream
(326) as
described above with reference to Figure 1.
[00103] The method may comprise combining at least a portion of the rich
bitumen
extract stream (318) with at least a portion of the lean bitumen extract
stream (326) in a
deasphalting unit (328) to form a diluted bitumen extract stream (not shown).
Additional
aliphatic solvent may be added to the diluted bitumen extract stream to
precipitate
asphaltenes, forming a deasphalted bitumen extract stream (329) and separated
asphaltenes
(330). The deasphalted bitumen extract (329) may be separated by a splitter
(327) into a
deasphalted extraction liquor (332) and a diluted bitumen product stream
(331). The
deasphalted extraction liquor (332) can be used as the first extraction liquor
(304) for adding
to the bituminous feed (302) and/or as the second extraction liquor (305) for
adding to the oil
sand slurry (308).
[00104] The deasphalting unit (328) may separate the diluted bitumen
extract stream
with a separator. The separator (328) may separate the deasphalted bitumen
extract stream
into a deasphalted extraction liquor (332) and a diluted bitumen product
stream (331).
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CA 02867357 2014-10-16
[00105] The method may comprise obtaining a bitumen product stream (338)
by
removing a first solvent (336) from the diluted bitumen product stream (331).
The solvent
(336) may be removed from the diluted bitumen product stream (331) in a
solvent recovery
unit (334). The bitumen product stream (338) may have a solids content of less
than 1 wt. %,
or less than 0.1 wt. %. Solvent can be removed from the diluted bitumen
product stream
(331) to produce the bitumen product stream (338) with a substantially low
solids content.
The substantially low solids content may render the bitumen suitable for
downstream refining
operations.
[00106] The method may comprise obtaining a low grade bitumen product
stream by
removing the first solvent from the precipitated asphaltenes to obtain a low
grade bitumen
product stream. The precipitated asphaltenes may be mixed with the rich
bitumen extract
stream.
[00107] The deasphalting of the diluted bitumen extract stream, of the
process depicted
in Figure 3, has the advantage of controlling the location within the solvent
extraction process
where asphaltenes are precipitated. Precipitated asphaltenes and fine solids
may be readily
separated from the diluted bitumen extract stream in the separator (327). The
deasphalted
bitumen extract stream (329) can be separated into the deasphalted extraction
liquor and the
diluted bitumen product stream with both streams having favorable properties.
The diluted
bitumen product stream has the advantage that residual solid fines are removed
during the
deasphalting process and results in a low ash bitumen product. The deasphalted
extraction
liquor has the advantage of being an extraction liquor that may more readily
dissolve bitumen
from the bituminous feed due to the absence of asphaltene molecules that
reduce the rate of
bitumen dissolution. The use of a deasphalted extraction liquor can result in
an increase in
bitumen recovery from a bituminous feed. The deasphalted extraction liquor has
the
advantage of limiting fouling by asphaltene precipitation within the process
equipment
pipelines used to transfer the deasphalted extraction liquor to the bituminous
feed. The lower
solid content of the deasphalted extraction liquor may also reduce the chance
of catastrophic
plugging of process equipment, including pipelines, by settling solids. The
deasphalted
bitumen may have an asphaltene content of less than 15 wt.%, less than 10
wt.%, or less than
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CA 02867357 2014-10-16
wt.%. The deasphalted bitumen may have an undissolved (precipitated)
asphaltene content
of less than 1 wt.%, less than 0.5 wt.%, or less than 0.2 wt.%. To achieve
these undissolved
(precipitated) asphaltene contents, the deasphalted bitumen may be subjected,
for instance, to
gravity separation.
[00108] Figure 4 is a flow chart of a method for processing a bituminous
feed. The
method may de-asphalt and solvent extract with solids agglomeration.
[00109] The method may comprise forming an oil sands slurry (408) by
contacting a
bituminous feed (402) with a first extraction liquor (404) comprising a first
solvent in a
bitumen extraction step (406). The oil sands slurry (408) may comprise a
bitumen extract and
solids. The first extraction liquor (404) may be comprised of the same
components of the first
extraction liquor (104) previously described. A second solvent (442) may be
added in the
bitumen extraction step (406). The second solvent (442) may contact the
bituminous feed
(402) to help form the oil sand slurry (408).
[00110] The method may comprise diluting the oil sands slurry (408) prior
to
separating the solids in the oil sands slurry (408) from the bitumen extract
in the oil sands
slurry (408). The oil sands slurry (408) may be diluted in a dilution step
(410) to form a
diluted oil sand slurry (447). The oil sands slurry (408) may be diluted by a
second extraction
liquor (407). The oil sands slurry (408) may be diluted by a third solvent
(444).
[00111] An aqueous bridging liquid (445) may be added to the oil sand
slurry (408) as
part of an agglomeration step (446) to agglomerate the solids in the slurry
and form an
agglomerated slurry (448). As described above, the aqueous bridging liquid may
wet the
solids and displace the suspension liquid on the surface of the solids. The
aqueous bridging
liquid may be referred to as a bridging liquid. As a result of interfacial
forces among three
phases (i.e. the aqueous bridging liquid, the suspension liquid, and the
solids), fine particles
within the solids may consolidate into larger, compact agglomerates that are
more readily
separated from the suspension liquid.
[00112] The method may comprise forming a rich bitumen extract stream
(418) and
separated solids (416) by separating the bitumen extract from the solids in a
separation step
- 29 -
CA 02867357 2014-10-16
(414) as described with reference to Figure 1. The separated solids may be
referred to as
residual solids.
[00113] The method may comprise forming a washed agglomerated solids
stream (424)
and a lean bitumen extract stream (426) by washing the separated solids (416)
with an
aliphatic solvent (422) in a washer unit (420). The aliphatic solvent (422)
may be used to
precipitate asphaltenes removed from the washer unit (420) as part of the lean
bitumen extract
stream (426) as described above with reference to Figure 1.
[00114] The method may comprise forming a diluted bitumen extract stream
by
combining a portion (419) of the rich bitumen extract stream (418) with a
portion of the lean
bitumen extract stream (426) in a deasphalting unit (428). The method may
comprise forming
the portion of the rich bitumen extract stream (419) that contacts the portion
of the lean
bitumen extract stream (426) in a liquid splitter (440) such as the liquid
splitter (240)
previously described with respect to Figure 1. The liquid splitter (440) may
function in the
same way as the liquid splitter (240) previously described with respect to
Figure 1 to split the
rich bitumen extract stream (218) into the portion of the rich bitumen extract
stream (419),
which contacts the portion of the lean bitumen extract stream (426), and a
second portion of
the rich bitumen extract stream (404). The second portion of the rich bitumen
extract stream
(404) may be the same as the second portion of the rich bitumen extract stream
(204)
discussed with respect to Figure 1. The portion of the lean bitumen extract
stream (426) may
be mixed with the portion of the rich bitumen extract stream (418) to help
remove residual
fine solids from the portion of the rich bitumen extract stream (418). The
portion of the rich
bitumen extract stream (419) may be referred to as a first portion of the rich
bitumen extract
stream. The second portion of the rich bitumen extract stream (404) may be
referred to as a
portion of the rich bitumen extract stream.
[00115] The second portion of the rich bitumen extract stream (404) may
not be mixed
with the rich bitumen extract stream. The second portion of the rich bitumen
extract stream
(404) may be deasphalted, in a fashion similar to what is described with
respect to Figure 1, to
produce a deasphalted lean bitumen extract stream. The deasphalted lean
bitumen extract
stream may be used as part of the second extraction liquor (407).
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CA 02867357 2016-06-28
,
,
[00116] The method may comprise separating the diluted bitumen
extract stream, in a
solid-liquid separation step, to form a low solids bitumen extract stream
(431), settled solids
and undissolved asphaltenes (430).
[00117] The method may comprise obtaining another bitumen product
stream (438) by
removing the first solvent (436) from the low solids bitumen extract stream
(431). The
solvent (436) may be removed from the low solids bitumen extract stream (431)
in a solvent
recovery unit (434). The another bitumen product stream (438) may have a
solids content of
less than 1 wt. %, or less than 0.1 wt. %. Solvent can be removed from the low
solids
bitumen extract stream (431) to produce the another bitumen product stream
(438) with a
substantially low solids content. The substantially low solids content may
render the bitumen
suitable for downstream refining operations.
[00118] Solvent extraction with solid agglomeration process is one
suitable solvent
extraction process for use with the processes described in the present
disclosure. The portion
of the rich bitumen extract stream may be recycled so that it is used as the
first extraction
liquor. Using a portion of the rich bitumen extract stream as the first
extraction liquor ensures
that the S:B of the initial bitumen extract obtained from dissolution of
bitumen from the
bituminous feed is less than the S:B of the bitumen extract. The lower S:B
ratio has the
advantage of increasing the amount of bitumen dissolution from the bituminous
feed, which
may increase overall bitumen recovery. However, the complete or near complete
dissolution
of the bitumen will result in fine solids dispersing into the bitumen extract
which, if left
dispersed, will hamper solid-liquid separation downstream of the solvent
extraction process.
Dispersion of the fine solids prior to solid agglomeration is acceptable
because the solid
agglomeration process will allow for the majority of the fine solids to be
recaptured as
agglomerates with the bridging liquid. The temperature, pressure, solvent
composition,
extraction liquor composition(s), and/or S:B of the bitumen extract may be
configured to
minimize the presence of undissolved asphaltenes. The temperature, pressure,
solvent
composition, extraction liquor composition(s), and/or S:B of the bitumen
extract may be
configured to minimize the presence of undissolved asphaltenes by keeping a
value of the
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CA 02867357 2014-10-16
temperature, pressure, solvent composition, extraction liquor composition(s),
and/or S:B of
the bitumen extract at a value that minimizes the presence of undissolved
asphaltenes.
[00119] The residual solids that remain in the rich bitumen extract stream
may be
removed by mixing a portion of the rich bitumen extract stream with some or
all of the lean
bitumen extract stream. The increased S:B ratio of the diluted bitumen extract
stream may
cause the residual solids to aggregate with or without accompanying asphaltene
precipitation.
The aggregated fine solids may readily be separated from the diluted bitumen
extract stream
in a separator (428). The solvent can be removed from the diluted bitumen
extract stream to
produce a bitumen product stream with a solid content of less than 0.1 wt.%.
The underflow
stream from the separation process may be recycled upstream of the separation
process in
order to recover residual bitumen extract from the solid agglomerates. For
example, the
underflow comprised of undissolved asphaltenes may be recycled and mixed with
the rich
bitumen extract stream to assist with the aggregation of the fine solids. In
cases when
precipitated asphaltenes are aggregated with the fine solids, the solvent can
be recovered from
the underflow extract stream to produce a low grade bitumen product with
commercial value.
[00120] Figures 6 and 8 are a flow charts of a method for processing a
bituminous feed.
[00121] The method may comprise forming an oil sand slurry (808) by
contacting a
bituminous feed (802) with a first extraction liquor (804), in a bitumen
extraction step (806),
(602), as described above with reference to Figure 1. The oil sand slurry
(808) may comprise
a bitumen extract and solids, as described above with reference to Figure 1.
The first
extraction liquor (804) may comprise a first solvent, as described above with
reference to
Figure 1.
[00122] The method may comprise forming a rich bitumen extract stream
(818) and
separated solids (816) by separating the solids from the bitumen extract,
(604), as described
above with reference to Figure 1. The method may comprise forming the rich
bitumen extract
stream (818) and the separated solids (816) in a solid-liquid separator (814),
as described
above with reference to Figure 1.
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CA 02867357 2014-10-16
[00123] The method may comprise providing a hydrocarbon fluid (850)
comprising
undissolved asphaltenes (606). The hydrocarbon fluid (850) may be any suitable
hydrocarbon
fluid for increasing the solvent to bitumen ratio and to precipitate
asphaltenes as described
above with reference to Figure 1.
[00124] The method may comprise forming an asphaltene-bitumen extract
mixture
(852) by mixing the hydrocarbon fluid (850) with the rich bitumen extract
stream (818),
(608). The hydrocarbon fluid (850) may be mixed with the rich bitumen extract
stream (818)
in a mixer (851). The mixer (851) may be any suitable mixer to combine the two
streams.
[00125] The method may comprise forming a low solids bitumen extract
stream (854)
by separating asphaltenes and residual fine solids (856) from the asphaltene-
bitumen extract
mixture (852), (610). The method may comprise forming the low solids bitumen
extract
stream (854) and the asphaltenes and residual fine solids (856) in a solid-
liquid separator
(853), as described above with reference to Figure 1.
[00126] The method may comprise obtaining a bitumen product stream (858)
by
removing the first solvent (860) from the low solids bitumen extract stream
(854), (612), as
described above with reference to Figure 1. The bitumen product stream (858)
may be
obtained by removing the first solvent (860) in a solvent recovery step (862).
[00127] Figures 7 and 9 are flow charts of a method for processing a
bituminous feed.
[00128] The method may comprise providing an extraction liquor (904)
comprising
deasphalted bitumen and a first solvent, in a solvent extraction step (906),
(702), as described
above with reference to Figure 1.
[00129] The method may comprise forming an oil sand slurry (908) by
contacting the
bituminous feed (902) with the extraction liquor (904), (704), as described
above with
reference to Figure 1. The oil sand slurry (908) may comprise a bitumen
extract and solids.
[00130] The method may comprise forming a rich bitumen extract stream
(918) by
separating the solids (916) from the bitumen extract (706), as described above
with reference
to Figure 1. The rich bitumen extract stream (918) may be separated from the
solids (916) in
a solid-liquid separator (914), as described above.
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CA 02867357 2016-06-28
,
,
[00131] The method may comprise obtaining a bitumen product stream
(962) by
removing the first solvent (964) from a portion of the rich bitumen extract
stream (918) (708),
as described above (708) with reference to Figure 1. The bitumen product
stream (962) may
be obtained by removing the first solvent (964) in a solvent recovery step
(968).
[00132] The deasphalted bitumen within the first extraction liquor
may have several
advantages. The deasphalted bitumen may be more readily able to dissolve
bitumen from the
bituminous feed. The deasphalted bitumen may be more readily able to dissolve
bitumen
from the bituminous feed due to a reduced amount of asphaltene content. The
reduced
amount of asphaltene content can reduce a rate of bitumen dissolution.
Therefore, the
deasphalted bitumen may increase bitumen dissolution in the first extraction
liquor.
Therefore, the deasphalted bitumen may result in an increase in bitumen
recovery from a
bituminous feed. The deasphalted bitumen may have the advantage of limiting
fouling by
asphaltene precipitation. The deasphalted bitumen may limit fouling by
asphaltene
precipitiation within the process equipment pipelines used to transfer the
deasphalted bitumen
to the bituminous feed because of the lower asphaltene content of the
deasphalted bitumen.
The deasphalted bitumen may reduce the chance of catastrophic plugging of
process
equipment, including pipelines, by settling solids. The lower solid content of
the deasphalted
bitumen may allow for this reduction. The deasphalted bitumen may allow for
the removal of
residual solid fines during deasphalting to produce reduced ash and increased
API bitumen
product, as compared to a bitumen extract stream that has not been
deasphalted, when solvent
is removed from the deasphalted bitumen. The deasphalted bitumen may have an
asphaltene
content of less than 15 wt.%, less than 10 wt.%, or less than 5 wt.%. The
deasphalted
bitumen may have an undissolved (precipitated) asphaltene content of less than
1 wt.%, less
than 0.5 wt.%, or less than 0.2 wt.%. To achieve these undissolved
(precipitated) asphaltene
contents, the deasphalted bitumen may be subjected, for example but not
limited to, to gravity
separation.
[00133] Examples
[00134] A bituminous feed of oil sand (10.3 wt.% bitumen, 3.5 wt.%
water, 27.8 wt.%
fines) was mixed with a pentane-bitumen extraction liquor (first extraction
liquor) at 1500
- 34 -
CA 02867357 2016-06-28
,
,
rpm for 15 minutes at room temperature in a mixing vessel (bitumen extraction
step) to form
an oil sand slurry. The oil sand slurry was 50 wt.% solids and at a solvent-to-
bitumen ratio of
0.8. After 15 minutes of mixing, water was added as a bridging liquid and
adjusted to achieve
a final water-to-solids ratio of 0.08. The oil sand slurry was mixed at 1500
rpm for 2 minutes
to achieve microagglomerates via spherical agglomeration. The agglomerated
slurry was
filtered (solid-liquid separation step), followed by washing of the separated
solids with
pentane (aliphatic solvent) using a wash ratio of 0.7 mL of solvent/g of
solids. Two tests were
performed according to the above procedure.
[00135] Test 1: The bitumen of the pentane-bitumen extraction
liquor (first extraction
liquor) was a non-deasphalted bitumen comprising approximately 18 wt.%
asphaltenes.
[00136] Test 2: The bitumen of the pentane-bitumen extraction
liquor (first extraction
liquor) was a partially deasphalted bitumen comprising approximately 9 wt. %
asphaltenes.
[00137] Bitumen recovery was determined by the Dean-Stark method.
In the
Dean-Stark method, a weighed sample is separated into bitumen, water, and
solids by
refluxing toluene. Condensed toluene and co-distilled water an continuously
separated in a
trap designed to recycle the solvent through an extraction thimble, dissolving
the bitumen
present in the sample, while the water is retained in the trap. Once the three
components have
been physically separated, they can be determined by various means. Test 1,
using a partially
deasphalted bitumen (first extraction liquor), had a total bitumen recovery of
85%. Test 2,
using a deasphalted bitumen (first extraction liquor), had a total bitumen
recovery of 90%.
This result strongly suggests that a deasphalted bitumen has the advantage of
producing an
extraction liquor that more readily extracts bitumen from the bituminous feed.
[00138] The scope of the claims should not be limited by particular
embodiments set
forth herein, but should be construed in a manner consistent with the
specification as a whole.
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