U.S. patent application number 13/559124 was filed with the patent office on 2013-01-31 for methods for extracting bitumen from bituminous material.
This patent application is currently assigned to MARATHON OIL CANADA CORPORATION. The applicant listed for this patent is Cherish M. Hoffman, Mahendra Joshi, Julian Kift, Whip C. Thompson, Dominic J. Zelnik. Invention is credited to Cherish M. Hoffman, Mahendra Joshi, Julian Kift, Whip C. Thompson, Dominic J. Zelnik.
Application Number | 20130026078 13/559124 |
Document ID | / |
Family ID | 47596355 |
Filed Date | 2013-01-31 |
United States Patent
Application |
20130026078 |
Kind Code |
A1 |
Joshi; Mahendra ; et
al. |
January 31, 2013 |
Methods for Extracting Bitumen From Bituminous Material
Abstract
Methods for preparing solvent-dry, stackable tailings. The
method can include the steps of adding a first quantity of solvent
to a bitumen material to form a first mixture, separating a first
quantity of bitumen-enriched solvent from the first mixture and
thereby creating solvent-wet tailings, and adding a quantity of
water to the solvent-wet tailings to separate a solvent component
from the solvent-wet tailings and thereby forming solvent-dry,
stackable tailings. The solvent used in the methods can include
paraffinic solvent, such as pentane.
Inventors: |
Joshi; Mahendra; (Katy,
TX) ; Kift; Julian; (Reno, NV) ; Hoffman;
Cherish M.; (Reno, NV) ; Thompson; Whip C.;
(Reno, NV) ; Zelnik; Dominic J.; (Sparks,
NV) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Joshi; Mahendra
Kift; Julian
Hoffman; Cherish M.
Thompson; Whip C.
Zelnik; Dominic J. |
Katy
Reno
Reno
Reno
Sparks |
TX
NV
NV
NV
NV |
US
US
US
US
US |
|
|
Assignee: |
MARATHON OIL CANADA
CORPORATION
Calgary
CA
|
Family ID: |
47596355 |
Appl. No.: |
13/559124 |
Filed: |
July 26, 2012 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61511913 |
Jul 26, 2011 |
|
|
|
61525582 |
Aug 19, 2011 |
|
|
|
Current U.S.
Class: |
208/390 ;
208/424; 208/434 |
Current CPC
Class: |
C10G 1/045 20130101 |
Class at
Publication: |
208/390 ;
208/434; 208/424 |
International
Class: |
C10G 1/04 20060101
C10G001/04; C10G 1/00 20060101 C10G001/00 |
Claims
1. A method comprising: passing a solvent through a first quantity
of bituminous material; and passing water through the first
quantity of bituminous material; wherein the solvent comprises a
paraffinic solvent.
2. The method as recited in claim 1, further comprising: loading
the first quantity of bituminous material into a sealed vessel
prior to passing the solvent and the water through the first
quantity of bituminous material.
3. The method as recited in claim 2, wherein the sealed vessel is a
sealed vertical column having a top end and a bottom end opposite
the top end.
4. The method as recited in claim 3, wherein passing the solvent
through the first quantity of bituminous material comprises: adding
the solvent at the top end of the sealed vertical column;
introducing inert gas into the sealed vertical column at the top
end of the sealed vertical column and pushing the solvent down
through the bituminous material loaded in the sealed vertical
column; and collecting the solvent exiting the bottom end of the
sealed vertical column.
5. The method as recited in claim 3, wherein the solvent exiting
the bottom end of the vertical column comprises solvent and
bitumen.
6. The method as recited in claim 2, wherein passing the water
through the first quantity of bituminous material comprises: adding
the water at a top end of the vertical column; introducing inert
gas into the vertical column at the top end of the vertical column
and pushing the water down through the bituminous material loaded
in the vertical column; and collecting residual solvent exiting the
bottom end of the vertical column.
7. The method as recited in claim 1, wherein the bituminous
material comprises oil sand.
8. The method as recited in claim 1, wherein the bituminous
material is solvent-wet.
9. The method as recited in claim 2, wherein the bituminous
material loaded in the vertical column comprises a plurality of
interstitial pores, and wherein the ratio of volume of water passed
through the first quantity of bituminous to total volume of the
plurality of interstitial pores is from 1:1 to 5:1.
10. The method as recited in claim 2, further comprising: removing
the first quantity of bituminous material from the sealed vessel
after passing the water through the first quantity of bituminous
material.
11. The method as recited in claim 10, wherein the bituminous
material removed from the sealed vessel comprises less than 200 ppm
on a weight basis of solvent and less than 2% by weight
bitumen.
12. A method comprising: providing a bituminous material comprising
a paraffinic solvent; passing water through the bituminous material
and pushing paraffinic solvent out of the bituminous material; and
collecting paraffinic solvent pushed out of the bituminous
material.
13. The method as recited in claim 12, wherein the bituminous
material comprises bitumen-depleted tailings derived from oil
sands.
14. A method comprising: contacting a bituminous material with a
solvent and forming solvent-wet bituminous material; contacting the
solvent-wet bituminous material with water and forming a water-wet
bituminous material; wherein the solvent comprises a paraffinic
solvent.
15. The method as recited in claim 14, wherein contacting the
bituminous material with the solvent comprises: mixing the
bituminous material with the solvent and forming the first
solvent-wet bituminous material; and separating a bitumen-enriched
solvent phase from the first solvent-wet bituminous material using
a hydrocyclone.
16. The method as recited in claim 14, wherein contacting the
solvent-wet bituminous material with the water comprises: mixing
the solvent-wet bituminous material with water and forming the
water-wet bituminous material; and separating a mixture of solvent
and water from the water-wet bituminous material using a
hydrocyclone.
Description
[0001] This application claims priority to U.S. Provisional Patent
Application No. 61/511,913, filed Jul. 26, 2011, and U.S.
Provisional Patent Application No. 61/525,582, filed Aug. 19, 2011.
Each application is incorporated herein by reference in its
entirety.
BACKGROUND
[0002] Bitumen is a heavy type of crude oil that is often found in
naturally occurring geological materials such as oil sands, black
shale, coal formations, and weathered hydrocarbon formations
contained in sandstones and carbonates. Some bitumen may be
described as flammable brown or black mixtures or oil like
hydrocarbons derived naturally or by distillation from petroleum.
Bitumen can be in the form of anywhere from a viscous oil to a
brittle solid, including asphalt, oils, and natural mineral waxes.
Substances containing bitumen may be referred to as bituminous,
e.g., bituminous coal, bituminous oil, or bituminous pitch. At room
temperature, the flowability of some bitumen is much like cold
molasses. Bitumen may be processed to yield oil and other
commercially useful products, primarily by cracking the bitumen
into lighter hydrocarbon material.
[0003] As noted above, oil sands represent one of the well known
sources of bitumen. Oil sands typically include bitumen, water, and
mineral solids. The mineral solids can include inorganic solids
such as coal, sand, and clay. Oil sand deposits can be found in
many parts of the world, including North America. One of the
largest North American oil sands deposits is in the Athabasca
region of Alberta, Canada. In the Athabasca region, the oil sands
formation can be found at the surface, although it may be buried
two thousand feet below the surface overburden or more.
[0004] Oil sands deposits can be measured in barrels equivalent of
oil. The Athabasca oil sands deposit has been estimated to contain
the equivalent of about 1.7 to 2.3 trillion barrels of oil. Global
oil sands deposits have been estimated to contain up to 4 trillion
barrels of oil. By way of comparison, the proven worldwide oil
reserves are estimated to be about 1.3 trillion barrels.
[0005] The bitumen content of some oil sands may vary from
approximately 3 wt % to 21 wt %, with a typical content of
approximately 12 wt %. Accordingly, an initial step in deriving oil
and other commercially useful products from bitumen typically can
require extracting the bitumen from the naturally occurring
geological material. In the case of oil sands, this may include
separating the bitumen from the mineral solids and other components
of oil sands.
[0006] One conventional process for separating bitumen from mineral
solids and other components of oil sands includes mixing the oil
sands with hot water and, optionally, a process aid such as caustic
soda (see, e.g., U.S. Pat. No. 1,791,797). Agitation of this
mixture releases bitumen from the oil sands and allows air bubbles
to attach to the released bitumen droplets. These air bubbles float
to the top of the mixture and form a bitumen-enriched froth. The
froth can include around 60% bitumen, 30% water, and 10% inorganic
minerals. The bitumen-enriched froth is separated from the mixture,
sometimes with the aid of a solvent, and further processed to
isolate the bitumen product.
[0007] For example, the froth can be treated with an aromatic
(naphtha-type) solvent to produce a clean bitumen product that can
serve as a refinery upgrader feed stock. The bulk of the mineral
solids can also be removed to form a tailings stream. The tailings
stream can also include water, solvent, precipitated asphaltenes
(in the case where the asphaltene is not soluble in the solvent
used to separate the bitumen-enriched froth from the mixture), and
some residual bitumen.
[0008] Tailings produced by the hot water process and/or the froth
treatment process can pose several problems. Firstly, as noted
above, the tailings produced by conventional methods can include
solvents, precipitated asphaltenes, or residual bitumen. The
bitumen and asphaltenes in a tailings stream represent unrecovered
hydrocarbon that will not be processed into valuable commercial
products. Accordingly, the conventional methods can result in a
lower yield of hydrocarbon material, and consequently, diminished
profit.
[0009] Additionally, the presence of bitumen and asphaltene in the
tailings can complicate the disposal of the tailings because these
materials present environmental risks. This can also be true for
residual solvent included in the tailings that can be
environmentally unfriendly.
[0010] The amount of tailings produced by conventional methods can
also present chemical and physical problems. In some circumstances,
the total volume of the tailings produced by the conventional
methods may be more than the volume of mined oil sands, which means
that not all of the tailings can be returned to the mined area.
[0011] The physical characteristics of the tailings can also
present problems. The conventional methods sometimes utilize water
and caustic as part of the process. This can result in the
activation and swelling of certain clay components of a tailings
stream. Accordingly, the tailings can have a sludge-like
consistency that may last indefinitely. The sludge-like consistency
means that the tailings are not stackable, thereby limiting the
manner in which to dispose of the tailings. Often the only disposal
option is to deposit the tailings in a tailings pond located
outside of the mine area. These ponds can be costly to build and
maintain and can be damaging to the local environment, including
the local water supply. Furthermore, ponds can be damaging to the
local wildlife population, such as birds, which can be caught in
the oil and solvent laden tailings produced by hot-water extraction
processes.
SUMMARY
[0012] Disclosed are embodiments of a method for producing
solvent-dry, stackable tailings, and the solvent-dry, stackable
tailings produced therefrom.
[0013] In some embodiments, a method of extracting bitumen from
bituminous material is disclosed. The method includes passing a
solvent through a first quantity of bituminous material and passing
water through the first quantity of bituminous material. The
solvent can be a paraffinic solvent. The method can produce
solvent-dry tailings due at least in part to the inclusion of a
water wash step that is capable of effectively removing solvent
from the tailings produced during the process. The solvent-dry
tailings are beneficial because they are easier to dispose of from
an environmental standpoint.
[0014] In some embodiments, a method for extracting bitumen from
bituminous material is disclosed. The method includes mixing
solvent with bituminous material and forming a mixture, separating
the mixture into a bitumen-enriched solvent phase and a
bitumen-depleted tailings phase, and passing water through the
bitumen-depleted tailings phase. The solvent can be a paraffinic
solvent. The method can produce solvent-dry tailings due at least
in part to the inclusion of a water wash step that is capable of
effectively removing solvent from the tailings produced during the
process. The solvent-dry tailings are beneficial because they are
easier to dispose of from an environmental standpoint.
[0015] In some embodiments, a method for extracting bitumen from
bituminous material is disclosed. The method includes contacting a
bituminous material with a solvent and forming solvent-wet
bituminous material, and contacting the solvent-wet bituminous
material with water and forming a water-wet bituminous material.
The solvent can be a paraffinic solvent. The method can produce
solvent-dry tailings due at least in part to the inclusion of a
water wash step that is capable of effectively removing solvent
from the tailings produced during the process. The solvent-dry
tailings are beneficial because they are easier to dispose of from
an environmental standpoint.
[0016] It is to be understood that the foregoing is a brief summary
of various aspects of some disclosed embodiments. The scope of the
disclosure need not therefore include all such aspects or address
or solve all issues noted in the Background above. In addition,
there are other aspects of the disclosed embodiments that will
become apparent as the specification proceeds.
[0017] Thus, the foregoing and other features, utilities, and
advantages of the subject matter described herein will be apparent
from the following more particular description of certain
embodiments as illustrated in the accompanying drawings. In this
regard, it is therefore also to be understood that the scope of the
invention is to be determined by the claims as issued and not by
whether given subject includes any or all features or aspects noted
in this Summary or addresses any issues noted in the
Background.
BRIEF DESCRIPTION OF THE DRAWINGS
[0018] The preferred and other embodiments are disclosed in
association with the accompanying drawings in which:
[0019] FIG. 1 is a flow chart detailing a method for producing
solvent-dry, stackable tailings as disclosed herein;
[0020] FIG. 2 is a schematic diagram for a system and method for
producing solvent-dry, stackable tailings as disclosed herein;
[0021] FIG. 3 is a schematic diagram for a system and method for
producing solvent-dry, stackable tailings as disclosed herein;
and
[0022] FIG. 4 is a schematic diagram for a system and method for
producing solvent-dry, stackable tailings as disclosed herein.
DETAILED DESCRIPTION
[0023] Before describing the details of the various embodiments
herein, it should be appreciated that the terms "solvent," "a
solvent" and "the solvent" may include one or more than one
individual solvent compounds unless expressly indicated otherwise.
Mixing solvents that include more than one individual solvent
compound with other materials can include mixing the individual
solvent compounds simultaneously or serially unless indicated
otherwise. It should also be appreciated that the term "oil sands"
includes oil sands. The separations described herein can be
partial, substantial or complete separations unless indicated
otherwise. All percentages recited herein are volume percentages
unless indicated otherwise.
[0024] Oil sands are used throughout this disclosure as a
representative bitumen material. However, the methods and systems
disclosed herein are not limited to processing of oil sands.
Applicant believes that any bitumen material may be processed by
the methods and systems disclosed herein.
[0025] With reference to FIG. 1, one embodiment of a method for
producing solvent-dry, stackable tailings includes a step 100 of
adding a first quantity of solvent to a bitumen material to form a
first mixture, a step 110 of separating a first quantity of
bitumen-enriched solvent phase from the first mixture, and a step
120 of adding a quantity of water to the remaining portion of the
first mixture, which can be considered solvent-wet tailings.
[0026] Step 100 of adding a first quantity of solvent to bitumen
material to form a first mixture represents a step in the solvent
extraction process (also sometimes referred to as dissolution,
solvation, or leaching). Solvent extraction is a process of
separating a substance from a material by dissolving the substance
of the material in a liquid. In this situation, the bitumen
material is mixed with one or more solvents to dissolve bitumen in
the solvent and thereby separate it from the other components of
the bitumen material (e.g., the mineral solids of oil sands).
[0027] The solvent used in step 100 can include a hydrocarbon
solvent. Any suitable hydrocarbon solvent or mixture of hydrocarbon
solvents that is capable of dissolving bitumen can be used. The
hydrocarbon solvent or mixture of hydrocarbon solvents can be
economical and relatively easy to handle and store. The hydrocarbon
solvent or mixture of hydrocarbon solvents may also be generally
compatible with refinery operations.
[0028] In some embodiments, the solvent is a paraffinic solvent.
Any paraffinic solvent suitable for use in dissolving bitumen can
be used. In some embodiments, the paraffinic solvent is pentane.
Other suitable paraffinic solvents include, but are not limited to,
ethane, butane, hexane and heptane
[0029] The solvent added into the bitumen material in step 100 need
not be 100% solvent. Other components can be included with the
solvent when it is added into the bitumen material. In some
embodiments, the solvent added into the column includes a bitumen
content. Solvent including a bitumen content can be referred to as
bitumen-enriched solvent, dissolved bitumen ("disbit"), or diluted
bitumen ("dilbit"). Bitumen-enriched solvent can be obtained from
bitumen extraction processes where a solvent has already been used
to extract bitumen from bitumen material. In some embodiments, the
bitumen-enriched solvent is bitumen-enriched solvent separated from
the first mixture in step 110 described in greater detail below and
recycled back within the method for use in step 100.
[0030] The bitumen material used in step 100 can be any material
that includes bitumen. In some embodiments, the bitumen material
includes any material having more than 3 wt % bitumen. Exemplary
bitumen materials include, but are not limited to, oil sands, black
shales, coal formations, and hydrocarbon sources contained in
sandstones and carbonates. The bitumen material can be obtained by
any known methods for obtaining bitumen material, such as by
surface mining.
[0031] In some embodiments, the bitumen material is subjected to
one or more pretreatment steps prior to being mixed with the
solvent. Any type of pretreatment step that will promote mixing
between the solvent and bitumen material and/or promote extraction
of bitumen from the bitumen material can be used. In some
embodiments, the pretreatment step involves heating the bitumen
material. In some embodiments, the bitumen material is heated to a
temperature in the range of from 30.degree. C. to 75.degree. C. Any
manner of heating the bitumen material can be used in the
pretreatment step. In some embodiments, the bitumen material is
heated by adding steam to the bitumen material. Immersed or
external heaters can also be used to heat the bitumen material.
[0032] While some embodiments include a bitumen material heating
pretreatment step as described above, other embodiments
specifically exclude any bitumen material heating pretreatment
steps. In such embodiments, the bitumen material is mixed with the
solvent at the naturally occurring temperature of the bitumen
material prior to mixing. The method can thereby eliminate the cost
associated with heating the bitumen and simplify the overall
method. In some embodiments the solvent is heated or retains heat
from the previous recovery steps in recovering solvent from the
bitumen.
[0033] The step of adding a first quantity of solvent to the
bitumen material to form a mixture can be performed as a
continuous, batch, or semi-batch process. Continuous processing may
typically be used in larger scale implementations. However, batch
processing may result in more complete separations than continuous
processing.
[0034] The solvent can be added to the bitumen material by any
suitable manner for ultimately forming a mixture of the two
components. For example, the solvent can be added to the bitumen
material by mixing the two components together. The mixing of the
bitumen material and the solvent is preferably carried out to the
point of dissolving most, if not all, of the bitumen contained in
the bitumen material. In some embodiments, the bitumen material and
the solvent are mixed in a vessel to dissolve the bitumen and form
the first mixture. The vessel can be selectively opened or closed.
The vessel used for mixing can also contain mechanisms for stirring
and mixing solvent and bitumen material to further promote
dissolution of the bitumen in the solvent. For example, powered
mixing devices such as a rotating blade may be provided to mix the
contents of the vessel. In another example, the vessel itself may
be rotated to cause mixing between the bitumen material and the
first solvent, such as shown in U.S. Pat. No. 5,474,397.
[0035] In certain embodiments, bitumen material and the solvent are
mixed by virtue of the manner in which the bitumen material and the
solvent are introduced into the vessel. That is to say, the solvent
is introduced into a vessel already containing bitumen material at
a high velocity, thereby effectively agitating and mixing the
contents of the vessel. Conversely, the bitumen material can be
introduced into a vessel already containing solvent.
[0036] In some embodiments the bitumen material and solvent are
mixed by introducing the solvent at a bitumen crushing stage that
takes place upstream of the main mixing step and which is aimed at
reducing the size of the bitumen material. The solvent can be added
to the bitumen material either in the crusher or prior to or after
the crusher. Further mixing can be undertaken during transport of
the mixture from the crusher to subsequent processing steps (e.g.,
by pumping the mixture and transporting the mixture in a
pipeline).
[0037] The amount of the solvent added to the bitumen material can
be a sufficient amount to effectively dissolve at least a portion,
or desirably all, of the bitumen in the bitumen material. In some
embodiments, the amount of the solvent mixed with the bitumen
material is approximately 0.5 to 4.0 times the amount of bitumen by
volume contained in the bitumen material, approximately 0.75 to 3.0
times the amount of the bitumen by volume contained in the bitumen
material, or preferably approximately 1.0 to 2.0 times the amount
of bitumen by volume contained in the bitumen material.
[0038] It should be noted that the ratio of the solvent to bitumen
can be affected by the amount of bitumen in the bitumen material.
For example, more solvent may be required for lower grade oils
sands ore (e.g., 6 wt % bitumen) than for average grade oil sands
ore (e.g., between 9 wt % and 14 wt % bitumen). Conversely, very
high grade oil sands ore (e.g., greater than 15 wt % bitumen) may
require a higher solvent to bitumen ratio again.
[0039] The first mixture of the solvent and the bitumen material
generally includes bitumen-enriched solvent, with the majority of
the bitumen from the bitumen material dissolved in the
bitumen-enriched solvent phase. In some embodiments, 90%,
preferably 95%, and most preferably 99% or more of the bitumen in
the bitumen material is dissolved in the solvent and becomes part
of the bitumen-enriched solvent. In some embodiments, the solvent
may be light enough to precipitate asphaltenes as a means to reject
the heavy portion of the bitumen within the bitumen material. In
such embodiments the total bitumen dissolved will be lower by
virtue of the asphaltene component rejection.
[0040] The bitumen-enriched solvent is separated from the first
mixture at step 110. Separation of the bitumen-enriched solvent
from the first mixture may result in the first mixture becoming
solvent-wet tailings when a portion of the solvent remains behind
in the primarily non-bituminous components of the first mixture
after separation of bitumen-enriched solvent. Any suitable process
for separating the bitumen-enriched solvent from the first mixture
can be used, such as by filtering bitumen-enriched solvent from the
first mixture (including but not limited to filtration via an
automatic pressure filter, vacuum filtration, pressure filtration,
and crossflow filtration), settling the first mixture and decanting
bitumen-enriched solvent off the top of the settled mixture, by
gravity or gas overpressure drainage of the bitumen-enriched
solvent from the first mixture, or by displacement washing of the
bitumen-enriched solvent from the first mixture. Any of these
separation methods can be used alone or in combination to separate
bitumen-enriched solvent from the first mixture.
[0041] In some embodiments, the bitumen-enriched solvent removed
from the first mixture includes from about 5 wt % to about 50 wt %
of bitumen and from about 50 wt % to about 95 wt % of the solvent.
The bitumen-enriched solvent may include little or no non-bitumen
components of the bitumen material (e.g., mineral solids). The
solvent-wet tailings created by removing the bitumen-enriched
solvent from the first mixture can include from about 75 wt % to
about 95 wt % non-bitumen components and from about 5 wt % to about
25 wt % solvent. The solvent component of the solvent-wet tailings
represents solvent mixed with the bitumen material but which is not
removed from the first mixture during separation step 110. This
solvent component of the solvent-wet tailings can have bitumen
dissolved therein. Accordingly, in some embodiments, the
solvent-wet tailings includes from about 1 wt % to about 5 wt % of
bitumen.
[0042] The vessel for mixing mentioned previously can function as
both a mixer and a separator for separating the bitumen-enriched
solvent from the first mixture. Alternatively, separate vessels can
be used for mixing and separating, wherein the first mixture is
transported from the mixing vessel to a separation vessel. In some
embodiments, the vessel is divided into sections. One section may
be used to mix the bitumen material and the solvent and another
section may be used to separate the bitumen-enriched solvent from
the first mixture.
[0043] The separation of the bitumen-enriched solvent from the
first mixture can be performed as a continuous, batch, or
semi-batch process. Continuous processing may typically be used in
larger scale implementations. However, batch processing may result
in more complete separations than continuous processing.
[0044] Separation of the bitumen-enriched solvent from the first
mixture by any of the above-mentioned methods can be preceded or
followed by applying pressurized gas over the first mixture.
Applying a pressurized gas over the first mixture can facilitate
the separation of the bitumen-enriched solvent from the non-bitumen
components of the solvent-wet tailings. Bitumen-enriched solvent
entrained between solid sand particles can then be removed by
applying additional solvent to the solvent-wet tailings as
described in greater detail below. The addition of additional
solvent can displace the liberated bitumen-enriched solvent from
the solvent-wet tailings by providing a driving force across a
filtration element (i.e., the non-bituminous components of the
bitumen material). Any suitable gas capable of displacing solvent
can be used. In some embodiments, the gas is nitrogen, carbon
dioxide, or steam. In some embodiments the pressurized gas may be
solvent vapor or superheated solvent of the same solvent that is
used in the dissolution stage. The gas can also be added over the
first mixture in any suitable amount. In some embodiments, 1.8
m.sup.3 to 10.6 m.sup.3 of gas per ton of bitumen material is used.
This is equivalent to a range of about 4.5 liters to 27 liters of
gas per liter of bitumen material. In certain embodiments, 3.5
ft.sup.3 of gas per ton of bitumen material is used.
[0045] Bitumen-enriched solvent separated during step 110 can be
subjected to further processing to separate the solvent from the
bitumen. Any suitable method of separating the two components can
be used. In some embodiments, the bitumen-enriched solvent is
heated to a temperature above the boiling temperature of the
solvent, resulting in the solvent evaporating off of the bitumen.
The evaporated solvent can be collected, condensed, and recycled
back in the extraction process.
[0046] After bitumen-enriched solvent has been separated from the
first mixture and solvent-wet tailings have been produced as a
result, a step 120 of adding a quantity of water to the solvent-wet
tailings is carried out in order to remove solvent from the
solvent-wet tailings. Addition of the water can displace the
solvent component and force the solvent out of the solvent-wet
tailings. As noted above, the solvent-wet tailings can include from
about 5 wt % to about 20 wt % of the solvent, and it is desirable
to remove this solvent from the tailings to make the tailings more
environmentally friendly. In some embodiments, the solvent also has
some bitumen dissolved therein, which will also be displaced from
the solvent-wet tailings.
[0047] Any manner of adding water to the solvent-wet tailings that
results in displacement of solvent from the solvent-wet tailings
can be used. In some embodiments, the manner in which the water is
added to the solvent-wet tailings is similar or identical to the
manner in which the first solvent is added to the first
mixture.
[0048] In some embodiments, water with an elevated temperature
(i.e., above room temperature) or steam is used to displace solvent
from solvent wet tailings. Water with an elevated temperature can
preferably be at a temperature greater than the boiling point
temperature of the solvent. When water at an elevated temperature
or steam is used, the introduction of the water or steam into the
solvent-wet tailings can serve to both displace the solvent and
remove solvent via evaporation. For example, steam may rapidly
condense once introduced into the solvent-wet tailings and transfer
heat to the solvent, resulting in solvent evaporation. Water at an
elevated temperature can be added with the solvent-wet tailings in
the same manner as water at room temperature. Steam can be injected
into the solvent-wet tailings. Any manner for injecting steam into
the solvent-wet tailings can be used. In some embodiments,
injection lines are inserted into the solvent-wet tailings through
which steam can be injected into the solvent-wet tailings.
[0049] The amount of the water or steam added to the solvent-wet
tailings can be sufficient to effectively displace and/or evaporate
at least a portion, or desirably all, of the solvent in the
solvent-wet tailings. The amount of water added to the solvent-wet
tailings can be approximately 0.5 to 4 times the amount of bitumen
by volume originally contained in the bitumen material. The amount
of steam added to the solvent-wet tailings can be approximately
less than or equal to 2 times the amount of bitumen by volume
originally contained in the bitumen material.
[0050] In some embodiments, the water is added in two or more
stages, with the water being in the same or different phases for
each stage. For example, in some embodiments, a first stage
addition of water includes the addition of water in a liquid phase,
and a second stage addition of water includes the addition of
steam. When water in a liquid phase is used for any stage, the
water can be at any suitable temperature, including water at
elevated temperatures.
[0051] In some embodiments, the addition of water to the
solvent-wet tailings results in the removal of 95% or more of the
solvent in the solvent-wet tailings. The solvent can leave the
solvent-wet tailings as a solvent-water mixture. The solvent-water
mixture can include from about 10 wt % to about 40 wt % solvent and
from about 60 wt % to about 90 wt % water. The mixture of water and
solvent can be collected and separated so that the water and
solvent can be reused in the extraction method. Any suitable method
for separating the water and solvent can be used. In some
embodiments, the water and solvent are separated based on
differences in boiling temperatures.
[0052] As with previously described separation steps, separation of
the solvent from the solvent-wet tailings by adding water can be
preceded or followed by applying pressurized gas over the
solvent-wet tailings. Applying a pressurized gas over the
solvent-wet tailings can facilitate the separation of the solvent
component of the solvent-wet tailings from the non-bitumen
components of the solvent-wet tailings. The liberated solvent can
then be displaced from the solvent-wet tailings by applying
additional water to the solvent-wet tailings. The application of a
gas overpressure can also displace solvent from the solvent-wet
tailings by providing a driving force across a filtration element
(i.e., the non-bituminous components of the solvent-wet tailings).
Any suitable gas for displacing solvent can be used. In some
embodiments, the gas is nitrogen, carbon dioxide or steam. The gas
can also be added over the mixture in any suitable amount. In some
embodiments, 1.8 m.sup.3 to 10.6 m.sup.3 of gas per ton of bitumen
material is used. This is equivalent to a range of about 4.5 liters
to 27 liters of gas per liter of bitumen material. In certain
embodiments, 3.5 ft.sup.3 of gas per ton of bitumen material is
used.
[0053] The solvent-dry, stackable tailings resulting from removal
of the solvent from the solvent-wet tailings generally include
inorganic solids, such as sand and clay, water, and little to no
solvent. As used herein, the term "solvent-dry" means containing
less than 0.1 wt % total solvent. As used herein, the term
"stackable" means having a water content of from about 2 wt % to
about 15 wt %. This range of water content can create damp tailings
that will not produce dust when transporting or depositing the
tailings. This range of water content can also provide stackable
tailings that will not flow like dry sand, and therefore have the
ability to be retained within an area without the need for
retaining structures (e.g., a tailings pond). This range of water
content can also provide tailings that are not so wet as to be
sludge-like or liquid-like. The solvent-dry, stackable tailings
produced by the above described method can also include less than 2
wt % bitumen (or greater if asphaltenes are rejected).
[0054] Generally speaking, the above-described process can be
considered advantageous over the previously known hot water bitumen
extraction process because water is used to remove solvent rather
than to extract bitumen from bitumen material. Avoiding the use of
water to extract bitumen can mitigate or eliminate many of the
problems discussed in greater detail above.
[0055] In some embodiments, the above described method may be
carried with the use of a plate and frame-type filter press. After
performing step 100 of mixing solvent with bitumen material, the
first mixture may be loaded into a plate and frame-type filter
press, at which point steps 110 and 120 may be carried out.
[0056] The plate and frame-type filter press may be any suitable
type of plate and frame-type filter press, including both vertical
and horizontal plate and frame-type filter presses. An exemplary
vertical plate and frame-type filter press suitable for use in this
method is described in U.S. Pat. No. 4,222,873. An exemplary
horizontal plate and frame-type filter press suitable for use in
this method is described in U.S. Pat. No. 6,521,135. Generally, the
first mixture may be pumped into frame chamber located between two
filter plates. The first mixture fills the frame chamber and, as
the frame chamber becomes fully occupied by the first mixture,
separation step 110 takes place as liquid bitumen-enriched solvent
migrates out of the frame chamber through the filter cloths of each
filter plate. The solid material of the first mixture remains
behind in the frame chamber.
[0057] Separation of the bitumen-enriched solvent from the first
mixture may also take place by adding additional solvent into the
filter press after loading the first mixture into the frame
chamber. The additional solvent pumped into the frame chamber may
serve to displace bitumen-enriched solvent from the frame chamber
and through the filter cloths. Any suitable amount of additional
solvent that will displace bitumen-enriched solvent from the frame
chamber may be introduced into the frame chamber. The solvent may
be the same solvent used when forming the first mixture in step 100
or may be another type of solvent as described in greater detail
above.
[0058] The addition of water to separate solvent can proceed in a
similar or identical fashion to the addition of solvent into the
frame chamber as described above. The addition of water into the
frame chamber loaded with solvent-wet tailings can displace solvent
through the filter cloths and out of the frame chamber.
[0059] When utilizing a filter press to carry out the method
described herein, pressurized gas can be injected into the frame
chamber before or after the addition of the first mixture, the
solvent, or the water. The addition of the pressurized gas can help
promote the separation of the materials targeted for separation by,
e.g., liberating the material from the mineral solids so that it
may more freely be removed upon subsequent addition of a
displacement liquid. The introduction of pressurized gas into the
frame chamber can proceed according to the details provided above
for applying pressurized gas over a first mixture.
[0060] In some embodiments, the above described method is carried
out by utilizing countercurrent washing. After step 100 of adding
solvent to bitumen material to form a first mixture, the 110 and
120 can take place by moving the various materials through each
other in opposite directions. For example, with respect to step
110, the separation step can be carried out by performing a
countercurrent washing process where solvent traveling in one
direction is passed through the first mixture traveling in an
opposite direction. In some embodiments, the first mixture is
loaded at the bottom of a screw classifier conveyor positioned at
an incline, while a second quantity of solvent may be introduced at
the top of the screw classifier conveyor. An exemplary screw
classifier conveyor suitable for use in this method is described in
U.S. Pat. No. 2,666,242. As the screw classifier conveyor moves the
first mixture upwardly, the second quantity of solvent flows down
the inclined screw classifier conveyor and passes through the first
mixture. The second quantity of solvent can displace
bitumen-enriched solvent contained in the first mixture, thereby
"washing" the bitumen-enriched solvent from the first mixture.
[0061] Separation of the bitumen-enriched solvent and the first
mixture may naturally occur based on the configuration of the screw
classifier conveyor, with the predominantly liquid bitumen-enriched
solvent collecting at one end of the washing unit and the
predominantly solid solvent-wet tailings at the opposite end of the
washing unit. For example, when an inclined screw classifier
conveyor is used, the bitumen-enriched solvent can collect at the
bottom of the screw classifier conveyor, while the solvent-wet
tailings can collect at the top of the screw classifier conveyor.
The bitumen-enriched solvent can include predominantly bitumen and
solvent.
[0062] The countercurrent process can include multiple stages. For
example, after a first pass of solvent through the first mixture,
the resulting bitumen-enriched solvent can be passed through the
resulting solvent-wet tailings several more times. Alternatively,
additional quantities of fresh solvent can be passed through the
resulting solvent-wet tailings one or more times. In this manner,
the bitumen-enriched solvent or fresh quantities of solvent can
become progressively more enriched with bitumen after each stage
and the solvent-wet tailings can lose progressively more bitumen
after each stage.
[0063] Steps 120 can be carried out in a similar fashion. The
solvent-wet tailings obtained after washing the first mixture in a
countercurrent process can be subjected to a countercurrent washing
with water. As the water passes through the solvent-wet tailings
traveling in an opposite direction, the water displaces the
solvent.
[0064] In some embodiments, the above described method is carried
out by utilizing a vertical column. The first mixture prepared in
step 100 can be loaded in a vertical column. Any method of loading
the first mixture in the vertical column can be used. The first
mixture can be poured into the vertical column or, when an
appropriate first mixture viscosity is obtained from mixing step
100, the first mixture can be pumped into the vertical column.
First mixture can generally be loaded in the vertical column by
introducing the first mixture into the column at the top end of the
vertical column. The bottom end of the vertical column can be
blocked, such as by a removable plug, valve, or by virtue of the
bottom end of the vertical column resting against the floor. In
some embodiments, a metal filter screen at the bottom end of the
vertical column is used to maintain the first mixture in the
vertical column. Accordingly, introducing first mixture at the top
end of the vertical column can fill the vertical column with first
mixture. In some embodiments, the vertical column is free of any
obstructions, such as platforms or stages. The amount of first
mixture loaded in the vertical column may be such that the first
mixture substantially fills the vertical column with first mixture.
In some embodiments, first mixture is added to the vertical column
to occupy 90% or more of the volume of the vertical column. In some
embodiments, the first mixture is not filled to the top of the
vertical column so that room is provided to inject first solvent,
second solvent, etc., into the vertical column.
[0065] In some embodiments, a pre-loading separation step is
carried out after the mixture has been prepared in step 100 but
before the mixture is loaded in the vertical column. The
pre-loading separation step can include separating a liquid
component of the first mixture from the first mixture. The liquid
component can include a quantity of the bitumen-enriched solvent
that is produced upon mixing the solvent and the bitumen material
to form the first mixture. Because this liquid component is
accessible immediately upon formation of the first mixture and
relatively easy to separate from the first mixture using basic
separation techniques, it can be separated from the first mixture
prior to performing the further separation steps that occur in the
vertical column and which are primarily aimed at separating the
more inaccessible quantities of the bitumen-enriched solvent
included in the first mixture.
[0066] The liquid component of the first mixture can be separated
from the first mixture prior to loading the first mixture in the
column by any suitable separation method capable of separating a
liquid component from a first mixture. In some embodiments, any
type of filtration process can be used wherein the liquid component
passes through a filtration medium that does not allow solid
particles of a certain size to pass therethrough. Accordingly, when
filtration is performed, the liquid component including
bitumen-enriched solvent passes through the filter while bitumen
material having some bitumen-enriched solvent entrained therein
will not pass through the medium. In other embodiments, the liquid
component is separated by decanting the first mixture. When
contained within a vessel, the first mixture can include a liquid
component that resides above the bitumen material. Accordingly, the
liquid component can be poured or skimmed off the top of the first
mixture to separate the liquid component from the remainder of the
first mixture.
[0067] In some embodiments where this pre-loading separation step
is carried out, the amount of solvent added to the bitumen material
to form the first mixture is more than is added when a pre-loading
separation step is not performed. The aim of adding this higher
amount of solvent is to create a liquid component that is plentiful
in the first mixture and relatively easy to access for purposes of
separation from the first mixture. In some embodiments, an amount
1.5 to 3 times the typical amount of solvent is used to ensure that
the pre-loading separation step may be carried out.
[0068] As mentioned previously, the solvent used in step 100 to
form the first mixture can be dilbit. In some embodiments, the
solvent used to form the first mixture is preferably
paraffinic-based dilbit when a pre-loading separation step is to be
carried out.
[0069] As noted above, the column can have a generally vertical
orientation. The vertical orientation can include aligning the
column substantially perpendicular to the ground, but also can
include orientations where the column forms angles less than
90.degree. with the ground. The column can generally be oriented at
any angle that results in gravity aiding the flow of the solvent
and water from one end of the column to the other. In some
embodiments, the column is oriented at an angle anywhere within the
range of from about 1.degree. to 90.degree. with the ground. In a
preferred embodiment, the column is oriented at an angle anywhere
within the range of from about 15.degree. to 90.degree. with the
ground.
[0070] The material of the vertical column is also not limited. Any
material that will hold the first mixture within the vertical
column can be used. The material can also preferably be a
non-porous material such that various liquids injected into the
vertical column only exit the column from one of the ends of the
vertical column. The material can be a corrosive resistant material
so as to withstand the potentially corrosive components of the
first mixture loaded in the column as well as any potentially
corrosive materials injected into the vertical column.
[0071] The shape of the vertical column is not limited to a
specific configuration. Generally speaking, the vertical column can
have two ends opposite one another, designated a top end and a
bottom end. The cross-section of the vertical column can be any
shape, such as a circle, oval, square or the like. The
cross-section of the vertical column can change along the height of
the column, including both the shape and size of the vertical
column cross-section. The vertical column can be a straight line
vertical column having no bends or curves along the height of the
vertical column. Alternatively, the vertical column can include one
or more bends or curves. In some embodiments, the interior chamber
of the vertical column is free of obstructions, such as platforms
or stages.
[0072] Any dimensions can be used for the vertical column,
including the height, inner cross sectional diameter and outer
cross sectional diameter of the vertical column. In some
embodiments, the ratio of height to inner cross sectional diameter
ranges from 0.5:1 to 15:1.
[0073] Once first mixture is loaded in the vertical column, the
separation and addition steps 110 and 120 are carried out. With
respect to step 110, separation of the bitumen-enriched solvent
from the mixture loaded in the column can be accomplished by adding
a second quantity of solvent into the vertical column. The second
quantity of solvent can be added into the vertical column at either
the top end of the column (down flow mode) or the bottom end of the
column (up flow mode). When a down flow mode is used, the second
quantity of solvent flows downwardly through the first mixture
loaded in the column. As the second quantity of solvent flows
downwardly through the column, it can displace bitumen-enriched
solvent from the column. When an up flow mode is used, the second
quantity of solvent flows upwardly through the first mixture loaded
in the column. As the second quantity of solvent flow upwardly
through the column, it can dissolve further bitumen contained in
the first mixture and displace bitumen-enriched solvent in the
first mixture. A gas overpressure as described in greater detail
above, can then be used to displace the dissolved bitumen and
solvent back down through the first mixture and out of the
column.
[0074] The second quantity of solvent can be added into the
vertical column by any suitable method. In some embodiments, the
second quantity of solvent is poured or pumped into the vertical
column at the top end and allowed to flow down through the first
mixture loaded therein under the influence of gravity. In some
embodiments, the second quantity of the solvent is pumped into the
column from the bottom end of the column. External pressures can
also be added to promote the downward flow of the solvent after it
has been added into the vertical column.
[0075] In some embodiments, the second quantity of solvent is added
to the vertical column under flooded conditions. In other words,
more solvent is added to the top of the vertical column than what
flows down through the first mixture, thereby creating a head of
solvent at the top of the vertical column.
[0076] Upon addition into the column in a down flow mode, the
solvent can flow downwardly through the height of the column via
small void spaces in the first mixture. The solvent can flow
downwardly through the force of gravity or by an external force
applied to the vertical column. Examples of external forces applied
include the application of pressure from the top of the vertical
column or the application of suction at the bottom of the vertical
column. The solvent can travel the flow of least resistance through
the first mixture. As the solvent flows downwardly through the
first mixture, bitumen enriched solvent contained in the first
mixture can be displaced downwardly through the column.
[0077] Upon addition into the column in an up flow mode, the
solvent flows upwardly through the height of the column via small
void spaces in the first mixture. The solvent can flow upwardly
through the continuous pumping of solvent into the column from the
bottom end of the column. As the solvent flows upwardly through the
first mixture, bitumen in the first mixture may be dissolved and
bitumen-enriched solvent contained in the first mixture may be
displaced upwardly. After the solvent has been added to the column
in an up flow mode, the dissolved bitumen and solvent can flow
downwardly back through the column as described above in the down
flow mode. The force acting on the dissolved bitumen and solvent
can either be gravity or an external force, such as a gas
overpressure.
[0078] The bitumen-enriched solvent that has flowed downwardly
through the height of the vertical column in either mode can exit
the bottom end of the vertical column, where it can be collected.
Any method of collecting the bitumen-enriched solvent can be used,
such as by providing a collection vessel at the bottom end of the
vertical column. The bottom end of the vertical column can include
a metal filter screen having a mesh size that does not permit first
mixture to pass through but which does allow for bitumen-enriched
solvent to pass through and collect in a collection vessel located
under the screen. Collection of bitumen-enriched solvent can be
carried out for any suitable period of time. In some embodiments,
collection is carried out for 2 to 30 minutes.
[0079] Bitumen-enriched solvent that has exited the column can be
recycled back into the top or bottom of the vertical column or
upstream of the column to perform further dissolution of any
undissolved bitumen still contained in the vertical column. The
collection and reintroduction of the bitumen-enriched solvent into
the column can be performed several times in an attempt to increase
the amount of bitumen removed from the column. Alternatively, or in
conjunction with adding bitumen-enriched solvent into the column,
further amounts of fresh solvent can be added to the column to
displace bitumen-enriched solvent.
[0080] With respect to step 120, water is added into the column in
the same manner as described above with respect to the addition of
the solvent into the column. The addition of water serves to
displace the solvent from the vertical column. Mixtures of water
and solvent can be collected and reintroduced into the column to
displace further solvent from the column. Alternatively or in
conjunction with adding the water and solvent mixture back into the
column, additional water can be added to the column to displace
further solvent from the column.
[0081] Step 120 can be carried out in two steps, with one step
occurring after the solvent-wet tailings have been discharged from
the column. In a first step, the solvent-wet tailings are
discharged from the column and a first portion of the quantity of
water is added to the solvent-wet tailings to separate a liquid
component from the solvent wet tailings. In a second step, the
solvent-wet tailings are re-loaded into the column and the second
portion of the first quantity of water is added to the solvent-wet
tailings loaded in the column. In some embodiments, 25% to 50% of
the water is used in the first portion and 50% to 75% of the water
is used in the second portion.
[0082] The material contained in the vertical column after the
removal of solvent generally includes solvent-dry stackable tails
as described in greater detail above. The solvent-dry, stackable
tails can be removed from the vertical column by any suitable
process. The solvent-dry, stackable tailings can be removed from
either the top end or the bottom end of the vertical column. In
some embodiments, the bottom end of the vertical column is covered
with one or more removable plugs or valves, and the one or more
plugs or valves can be removed to allow the solvent-dry, stackable
tailings to discharge out of the vertical column by the force of
gravity. For example, if the bottom end of the vertical column is
blocked by a screen as described in greater detail above, the
screen can be removed to allow the solvent-dry, stackable tailings
to flow out of the vertical column. Alternatively, the screen may
be an annular ring at the lower part of the column to allow
dissolved bitumen or liquids to pass without obstructing the
outflow of solids once the plug or valve is removed. In certain
embodiments, the vertical column is lifted off of the ground,
thereby allowing the solvent-dry, stackable tailings to flow out of
the bottom end of the vertical column. External forces can also be
applied to the vertical column to promote the discharging of the
solvent-dry, stackable tailings from the vertical column.
[0083] In some embodiments, the solvent and/or water added into the
column can be added into the column from the bottom of the column
to create an upflow of solvent or water into the column. Solvent or
water can be added in this manner to unplug a vertical column that
has become plugged. The bottom of the column may be closed off to
force the solvent or water upwards when introduced at the bottom of
the column. For example, increasing the flow rate and pressure of
the injected solvent or water can result in closing off the bottom
of the column. The upwardly moving solvent or water can then
displace or dissolve the material causing the plug in the
column.
[0084] With reference to FIG. 2, a system 200 for carrying out the
above-described method includes a mixer 205 for mixing bitumen
material 210 and solvent 215. Any suitable mixing vessel can be
used, including a mixing vessel that operates under pressure in
order to maintain the solvent 215 as a liquid. A first mixture 220
is formed by the mixing of the bitumen material 210 and the solvent
215 in the mixer 205. The first mixture 220 is transported to a
first separation unit 225 where bitumen-enriched solvent 230 is
separated from the first mixture 220. Any separation unit suitable
for separating the bitumen-enriched solvent 230 from the first
mixture 220 can be used. Gas 285-1 can be pumped into the first
separation unit 225 to promote separation of bitumen from the
non-bitumen components of the bitumen material. When gas 285-1 is
pumped into first separation unit 225, the spent gas may also exit
the first separation unit 225 with the bitumen-enriched solvent
230. Because the gas does not dissolve in either the bitumen or the
first solvent of the first mixture 220, the gas exits with the
bitumen-enriched solvent 230 and does not require any additional
separation processing (but may be recovered and reused from an
economics standpoint). Removal of the bitumen-enriched solvent 230
from the first mixture 220 via first separation unit 225 results in
the first mixture 220 becoming solvent-wet tailings 235. The
solvent-wet tailings 235 produced by the first separation unit 225
are transported to a second separation unit 260 where the solvent
265 is removed from the solvent-wet tailings 235 by adding water
270 to the solvent-wet tailings 235. Any separation unit suitable
for separating the solvent 265 from the solvent wet tailings 235
may be used. Separation of the solvent 265 from the solvent-wet
tailings 235 results in the solvent-wet tailings 235 becoming
solvent-dry, stackable tailings 275.
[0085] With reference to FIG. 3, a system 300 for carrying out the
extraction method disclosed herein that utilizes a vertical column
includes a mixing vessel 305 for mixing bitumen material 310 with a
first quantity of solvent 315 to form a first mixture 320. Any type
of mixing vessel may be used to mix the bitumen material 310 and
the solvent 315.
[0086] The first mixture 320 is then loaded in the vertical column
325. FIG. 3 depicts the first mixture 320 being loaded in the top
end of the vertical column 325, but the first mixture 320 can also
be loaded from the bottom end of the vertical column 325 or from
the side of the vertical column 325. Once the first mixture 320 is
loaded in the vertical column 325, a second quantity of solvent or
solvent vapor 330 is injected into the top end of the vertical
column. The second quantity of solvent 330 flows down the height of
the vertical column 325, dissolving solid bitumen in the first
mixture 320 and/or displacing dissolved bitumen in the first
mixture 320 along the way. The non-bitumen components of the
bitumen material remain in a packed condition in the vertical
column 325 as the second quantity of solvent 330 passes through the
first mixture 320. The second quantity of solvent 330 exits the
bottom end of the vertical column 325 as a bitumen-enriched solvent
phase 335. The second quantity of solvent 330 is now a
bitumen-enriched solvent phase 335 because the second quantity of
solvent 330 dissolves solid bitumen contained in the first mixture
320 and/or coalesces with dissolved bitumen contained in the first
mixture 320 as the second quantity of solvent 330 passed through
the vertical column 325.
[0087] The bitumen-enriched solvent phase 335 is collected at the
bottom end of the vertical column 325 for further processing of the
bitumen contained therein. Some of the second quantity of solvent
330 remains in the first mixture 320 loaded in the vertical column
325. Water 350 is added to the vertical column 325 to displace
solvent out of the vertical column 325. The water 350 flows down
the height of the vertical column 325, displacing solvent contained
in the first mixture 320. The water 350 exits the bottom end of the
vertical column 325 as a water and solvent mixture 355, which can
be separated into water and solvent so each component may be
reused.
[0088] Optionally, the system also includes one or more gas purge
injections 365-1 and 365-3. The gas purge injections 365-1 and
365-3 may occur before and/or after any of the solvent or water
injection steps, and may serve to help separate bitumen and first
solvent from the non-bitumen component of the first mixture
320.
[0089] After displacement of solvent, the material loaded in the
column 325 is solvent-dry, stackable tailings 360. The solvent-dry,
stackable tailings 360 is discharged out of the vertical column
325. FIG. 3 depicts solvent-dry, stackable tailings 360 being
removed from the bottom end of the vertical column 325, but the
solvent-dry, stackable tailings 360 may also be discharged from the
top end of the vertical column 325.
[0090] With reference to FIG. 4, a system for carrying out the
extraction method disclosed herein that utilizes countercurrent
washing includes loading a first mixture 410 of bitumen material
and solvent in a washing unit 405. The washing unit 405 receives
the first mixture 410 and transports it in a first direction while
moving solvent 415 towards the first mixture 410 in a direction
opposite the direction the first mixture 410 is traveling. The
first mixture 410 mixes with the solvent 415, during which
bitumen-enriched solvent in the first mixture 410 is displaced from
the first mixture 410 by the solvent or solvent vapor 415.
Bitumen-enriched solvent 420 and solvent-wet tailings 425 separate
due to the countercurrent configuration of the washing unit
405.
[0091] Solvent-wet tailings 425 are transported to a second washing
unit 450 where it flows in a direction opposite to a direction of
flow of water 455 introduced into the second washing unit 450. The
solvent-wet tailings 425 mix with the water 455, during which the
solvent in the solvent-wet tailings 425 is displaced by the water
455. Accordingly, solvent-water mixture 460 and solvent-dry,
stackable tailings 465 are formed. The solvent-water mixture 460
and the solvent-dry, stackable tailings 465 separate due to the
countercurrent configuration of the secondwashing unit 450. The
final stage 450 may be a column, vessel, or plate and frame filter
as described previously to effect a more efficient final water
removal to produce solvent-dry stackable tailings.
[0092] In any of the embodiments described herein, the method can
include a further step of depositing the solvent-dry, stackable
tailings in a mine pit formed when mining the first bitumen
material. The manner in which the solvent-dry, stackable tailings
are deposited in the mine pit is not limited. In one example, the
solvent-dry, stackable tailings is transported to the mine pit by
one or more trucks and poured into the mine pit from the trucks.
Solvent-dry, stackable tailings may also be deposited in a mine pit
through the use of conveyor belts that empty into the mine pits. In
some embodiments, the volume of solvent-dry, stackable tailings
produced from the mined bitumen material is less than the original
amount of bitumen material mined such that the entirety of the
solvent-dry, stackable tailings may be deposited in the mine pit.
To the contrary, conventional hot water processing of bitumen
material generally produce wet tailings having a volume that is
125% of the original volume of the mined bitumen material, even
after settling and decanting of excess liquid. Additionally, the
presence of some amount of water in the solvent-dry, stackable
tailings may aid in the compaction of the solvent-dry, stackable
tailings. This can lead to a much earlier trafficable reclamation
for the deposit, an aspect of tailings management which has not
been attained by oil sands operators to date.
[0093] As described in greater detail in U.S. Pat. Nos. 7,985,333
and 7,909,989, further processing can be performed on other
components produced by the methods described above. For example,
the bitumen-enriched solvent phase can be processed to separate the
bitumen therefrom. Furthermore, as described U.S. Published Patent
Application No. 2011/0017642, herein incorporated by reference, any
bitumen obtained from the above-described methods or from further
processing of the bitumen-enriched solvent phases produced by the
above-described processes can be cracked in a nozzle reactor (with
or without deasphalting) to produce light hydrocarbon distillate.
The light hydrocarbon distillate can then be used as a solvent to
extract bitumen from bitumen material. In one example, the light
hydrocarbon distillate produced is recycled within the same process
to initiate extraction of bitumen from further bitumen material.
Additionally, any solvent separated or removed from a mixture can
be recovered and reused in the process.
[0094] Paraffinic solvent can be present in the tailings as a
result of using paraffinic solvent to dissolve and extract bitumen
from the bituminous material. Water effectively removes paraffinic
solvent from the tailings at least in part because of the
immiscibility of the water and paraffinic solvent. For example,
when tailings are treated with water by passing a plug of water
through the tailings, the immiscibility of the water and paraffinic
solvent helps to ensure that the water pushes the paraffinic
solvent out of the tailings rather than mix with the paraffinic
solvent and potentially leave a mixture of paraffinic solvent and
water in the tailings.
[0095] In some embodiments, a method of performing bitumen
extraction on bituminous material that includes the formation of
solvent-dry tailings includes a step 500 of passing a solvent
through a first quantity of bituminous material, and a step of 510
of passing water through the first quantity of bituminous material.
In this method, the solvent is a paraffinic solvent.
[0096] In step 500, solvent is passed through a first quantity of
bituminous material. One aim of step 500 is to dissolve bitumen
contained in the bituminous material into the solvent as a means
for eventually extracting the bitumen content from the bituminous
material. The solvent typically passes through the bituminous
material by traveling through the interstitial spaces within the
bituminous material. As it passes through these spaces, the solvent
contacts bitumen contained in the bituminous material and dissolves
the bitumen. The solvent thus becomes "bitumen-enriched," and when
the bitumen-enriched solvent has passed all the way through the
bituminous material, bitumen content in the bituminous material has
been effectively extracted from the bituminous material.
[0097] The bituminous material can be similar or identical to the
bitumen material described in greater detail above. In some
embodiments, the bituminous material is oil sand or oil sand. In
some embodiments, the bituminous material is obtained from previous
bitumen extraction process steps. For example, in some embodiments,
oil sand or the like is mixed with solvent capable of dissolving
bitumen and the resulting mixture is separated into a
bitumen-enriched solvent phase and a bitumen-depleted tailings
phase. The mixing can be carried out in a mixing drum or the like,
and the separation can be carried out using a thickener,
hydrocyclone, or the like. The bitumen-enriched solvent phase can
be subjected to further processing that separates the solvent from
the bitumen. Separated solvent can be reused in the process and
bitumen can be subjected to upgrading processes. The
bitumen-depleted tailings phase from such a process will typically
include a solvent content and a bitumen content in addition to the
sand and clay of the original oil sand. For example, in some
embodiments, the bitumen-depleted tailings phase includes up to 40%
of the bitumen contained in the original oil sand. This
bitumen-depleted tailings can serve as the bituminous material used
in the method described herein.
[0098] Any technique that results in the passing of solvent through
the bituminous material can be used. In some embodiments, the
solvent is passed through the bituminous material by loading the
bituminous material in a vessel, adding solvent at one end of the
vessel, and causing the solvent to move through the bituminous
material to the opposite end of the vessel. Any vessel capable of
containing the bituminous material can be used, and the size and
shape of the vessel is not limited. Solvent can be moved through
the bituminous material using, for example, gravity or an external
force, such as the application of an inert gas at one end of the
vessel. When inert gas is used to move solvent through the
bituminous material, the vessel can be a sealed vessel, so that the
introduction of inert gas into one end of the vessel forces the
solvent to move through the bituminous material to the other end of
the vessel.
[0099] In some embodiments, the vessel or sealed vessel is a
vertical column as described in greater detail above. The
bituminous material is loaded in the vertical column as described
above, and solvent is added to the top end of the vessel such that
it may move downwardly through the bituminous material loaded in
the vertical column to the bottom end of the vessel. As mentioned
above, gravity can be relied on to move the solvent down through
the bituminous material, or the vertical column can be a sealed
vertical column and inert gas can be introduced at the top end of
the vertical column after solvent has been added into the column to
force the solvent to move downwardly through the bituminous
material loaded in the vertical column. When inert gas is used to
promote the movement of the solvent through the bituminous
material, the inert gas can be applied at a pressure ranging from
30 psig to 300 psig. Typically, the pressure at which the inert gas
is applied into vertical column can vary based on how packed the
bituminous material is in the vertical column, the height of the
column, and the resulting pressure drop over the column length. The
more packed the bituminous material, the greater the pressure will
need to be to move the solvent downwardly through the bituminous
material. Any suitable inert gas can be used, and in some
embodiments, the inert gas is nitrogen.
[0100] The solvent used in step 500 can be similar or identical to
the first solvent described in greater detail above. In some
embodiments, the first solvent is a solvent capable of dissolving
bitumen. In some preferred embodiments, the solvent is a paraffinic
solvent.
[0101] The amount of solvent passed through the bituminous material
in step 500 typically depends on the bitumen content of the
bituminous material, although other factors can impact how much
solvent is passed through the bituminous material. In some
embodiments, a ratio of solvent to bitumen content of the
bituminous material on a volume basis (or S:B ratio) is used to
specify the amount of solvent passed through the bituminous
material. The S:B ratio in step 500 can vary from between 0.5:1 to
4:1.
[0102] The solvent that passes through the bituminous material will
have a bitumen content based on the amount of bitumen that
dissolves into the solvent as it passes through the bituminous
material. In some embodiments, the solvent will have removed from
40% to 75% of the bitumen content of the bituminous material. The
solvent that passes through the bituminous material can therefore
be collected and subjected to further processing that separates the
solvent from the bitumen content. The separated solvent can be
reused in the process, and the bitumen can be subjected to
upgrading processes to produce lighter hydrocarbons.
[0103] In some embodiments, a portion of the solvent that is
introduced into the bituminous material will not pass all the way
through the bituminous material, and will instead remain in the
interstitial pores of the bituminous material. This trapped solvent
can still have dissolved bitumen therein, and therefore a step 510
of passing water through the bituminous material can be carried out
to remove solvent from the bituminous material. When the solvent is
paraffinic, the water is effective at displacing the solvent from
the bituminous material due to the immiscibility of the paraffinic
solvent and the water. For example, when a plug of water is moved
through the bituminous material, the paraffinic solvent is pushed
out of the bituminous material by the water plug rather than mixing
with the water, which could possibly lead to paraffinic solvent
remaining in the bituminous material.
[0104] Passing water through the bituminous material can be carried
out in a similar or identical fashion to how the solvent is passed
through the bituminous material. While any manner of passing the
water through the bituminous material can be used, some embodiments
call for the water to be passed through bituminous material loaded
in a vessel, such as a sealed vertical column. In such embodiments,
water is introduced at the top end of the sealed vertical column,
and moves downwardly through the bituminous material under the
force of gravity or through the application of external force. In
some embodiments, inert gas is introduced into the top end of the
sealed vertical column after water has been introduced into the top
end of the sealed vertical column to push the water downward
through the bituminous material. When inert gas is introduced, the
inert gas can be introduced at a pressure of from 30 to 50 psig. In
some embodiments, the pressure of the inert gas is kept relatively
low so as not to move the water through the bituminous material at
a velocity that results in disrupting the clays attached to the
sand particles in the bituminous material.
[0105] The amount of water used in step 510 can be based on a ratio
of volume of water added to the total volume of the interstitial
pore spaces in the bituminous material (W:P ratio). In some
embodiments, the W:P ratio for step 510 is from 1:1 to 5:1, meaning
that, generally speaking, a volume of water anywhere from one to
five times the volume of pore spaces in the bituminous material is
passed through the bituminous material.
[0106] The water passing through the bituminous material in step
510 will result in solvent and water exiting the bituminous
material. The solvent can include dissolved bitumen, and therefore
steps can be taken to separate the water, solvent, and bitumen. The
water and solvent (having bitumen dissolved therein) can be
relatively easy to separate due to the immiscibility of the solvent
in the water. In some embodiments, the solvent and water may
naturally phase separate, forming a layer of solvent over the
water. Once the solvent and water are separated, the solvent can be
processed to separate the solvent from the bitumen. Separated water
and solvent can be reused in the process, and bitumen can be
subjected to upgrading processing.
[0107] Any of the above described steps wherein solvent or water is
passed through the bituminous material can be performed in multiple
stages. That is to say, multiple quantities of solvent can be
passed through the bituminous material in individual stages prior
to passing any water through the bituminous material. Multiple
quantities of water can be passed through the bituminous material
in individual stages after the solvent wash has been completed.
Using multiple stages of washes for one or more of the solvent and
water can result in more complete removal of bitumen and solvent
from the bituminous material.
[0108] After steps 500 and 510 have been carried out, a tailings
phase is left over. When a vessel is used to carry out these steps,
the tailings can be discharged from the vessel. The tailings phase
generally includes the non-bitumen solid materials of the original
bituminous material, such as sand and clay. In conventional bitumen
extraction processes that utilize solvents, the tailings include a
solvent content. However, in the above method, the water wash can
result in the production of tailings that have less than 200 ppm
solvent. Additionally, the tailings can include less than 2 wt % of
the original bitumen content of the bituminous material. Bitumen
and solvent levels in these ranges can satisfy stringent
environmental regulations set by various organizations overseeing
oil sand mining and bitumen extraction.
[0109] The tailings can also include a water content due to the
water content present in the original bituminous material and the
water added to the bituminous material as part of removing solvent
from the bituminous material. In some embodiments, the water
content of the tailings is about 14 wt % and the tailings can be
transported by conveyor for deposition. In some embodiments, it may
be useful to add additional water to the discharged tailings so
that the tailings are in the form of a pumpable slurry.
[0110] In some embodiments, a method of extracting bitumen from
bituminous material and producing solvent-dry tailings includes a
step 600 of contacting a bituminous material with a solvent and
forming a solvent-wet bituminous material and a step 610 of
contacting the solvent-wet bituminous material with water and
forming a water-wet bituminous material. In the method described
above, the solvent is preferably a paraffinic solvent.
[0111] The first solvent, water, and bituminous material used in
steps 600 and 610 are similar or identical to the first solvent,
second solvent, and water described above in the method including
steps 500 and 510.
[0112] Each or both of the contacting steps 600 and 610 can include
passing the solvent and water through the bituminous material as
described in greater detail above. When a contacting step 600 or
610 includes passing one of the wash materials through the
bituminous material, the bituminous material becomes wet with
whichever of the wash materials is passed through the bituminous
material. For example, when bituminous material is contacted with
solvent by passing the solvent through the bituminous material, a
portion of the solvent becomes trapped in the bituminous material,
thereby making the bituminous material solvent-wet bituminous
material. When steps 600 and 610 include passing the wash material
through the bituminous material, the method is similar or identical
to the method described above (i.e., the method including steps 500
and 510).
[0113] Each or both of the contacting step 600 and 610 can also
include adding wash material to bituminous material and mixing the
two components into a mixture or slurry. Mixing can differ from
passing a wash material through the bituminous material in that a
mixing step does not require the movement of wash material from one
side of the bituminous material through to the opposite side of the
bituminous material and the discharge of a relatively large portion
of the wash material from the bituminous material. Rather, mixing
generally includes a majority or all of the wash material remaining
with the bituminous material in the form of a slurry and the two
components being mixed together.
[0114] Any suitable manner of mixing solvent or water with the
bituminous material can be used to carry out step 600 or 610. The
mixing can occur by adding both the bituminous material and the
wash material to a vessel and mixing the two components together to
form a slurry of bituminous material that is wet with the specific
wash material used in the contacting step. Mixing together the wash
material and the bituminous material can provide desirable results.
For example, when solvent is mixed with bituminous material, the
mixing promotes the dissolution of bitumen from the bituminous
material into the solvent.
[0115] In embodiments where any of the contacting steps 600 or 610
include mixing wash material with the bituminous material, the
contacting step can further include a step of separating out
certain components from the resulting mixture. When step 600
includes mixing, the separation step will generally include
separating a bitumen-enriched solvent phase from solvent-wet
bituminous material. When step 610 includes mixing, the separation
step will generally include separating a mixture of solvent and
water from the solvent-wet bituminous material. Any suitable
separation methods can be used to carry out the above-described
separations. Exemplary separation methods can include any of those
described in previous embodiments, including but not limited to,
filtering, settling and decanting, gravity or gas overpressure
drainage, and displacement washing.
[0116] In some embodiments, one or both of the separation steps
described above are carried out in a hydrocyclone. Generally
speaking, the mixture formed in step 600 or 610 is transported into
a hydrocyclone where the hydrocyclone acts to separate the mixture
into an overflow and an underflow. When the mixture formed in step
600 is separated in a hydrocyclone, the mixture will be separated
into a bitumen-enriched solvent overflow and a solvent-wet
bituminous material underflow. When the mixture formed in step 610
is separated in a hydrocyclone, the mixture will be separated into
a solvent and water mixture overflow and a water-wet bituminous
material underflow.
[0117] Any suitable hydrocyclone can be used to carry out the
separation process. Typical hydrocyclones suitable for use in the
above described method include hydrocyclone separators that utilize
centrifugal forces to separate materials of different density,
size, and/or shape. The hydrocyclone will typically include a
stationary vessel having an upper cylindrical section narrowing to
form a conical base. The mixtures are introduced into the
hydrocyclone at a direction generally perpendicular to the axis of
the hydrocyclone. This induces a spiral rotation on the mixture
inside the hydrocyclone and enhances the radial acceleration on the
solids within the mixture. The hydrocyclone also typically includes
two outlets. The underflow outlet is situated at the apex of the
cone, and the overflow outlet is an axial tube rising to the vessel
top (sometimes also called the vortex finder).
[0118] When the density of the solids is greater than that of the
fluid portion of the mixture, the heavier solid particles migrate
quickly towards the cone wall where the flow is directed downwards.
Lower density solid particles migrate more slowly and therefore may
be captured in the upward spiral flow and exit from vortex finder
via the low pressure center. Factors affecting the separation
efficiency include fluid velocity, density, and viscosity, as well
as the mass, size, and density of the tailings particles. The
geometric configuration of the hydrocyclone can also play a role in
separation efficiency. Parameters that can be varied to adjust
separation efficiency include cyclone diameter, inlet width and
height, overflow diameter, position of the vortex finder, height of
the cylindrical chamber, total height of the hydrocyclone, and
underflow diameter.
[0119] A separate hydrocyclone can be provided to carry out each of
the separation steps that occur after the contacting (i.e., mixing)
steps 600 or 610, or a single hydrocyclone can be used for one or
more separations. In embodiments where a separate hydrocyclone is
provided for each separation, a first hydrocyclone receives and
separates the first mixture formed in step 600, and a second
hydrocyclone receives and separates the second mixture formed in
step 610. Each of the hydrocyclones can be sized and configured
especially for the separation for which it is used.
[0120] When each separation step is carried out in a separate
hydrocyclone, the process can generally proceed as follows: A
bituminous material and a solvent are contacted so as to form a
first mixture. The first mixture is delivered into the first
hydrocyclone and separated into a bitumen-enriched solvent overflow
and a solvent-wet bituminous material underflow. The underflow is
contacted with water so as to form a second mixture. The second
mixture is delivered into the second hydrocyclone and separated
into a solvent and water overflow and a water-wet bituminous
material underflow.
[0121] In some embodiments, each separation step can include
multiple stages such that the mixture is passed through the
hydrocyclone multiple times before being passed through to the next
hydrocyclone. For example, the first mixture of bituminous material
and solvent can be passed through a hydrocyclone a first time,
followed by collecting the first solvent-wet bituminous material
overflow, adding an additional quantity of solvent, and passing the
resulting mixture through the same hydrocyclone. This can be
repeated numerous times to increase the separation efficiency. In
the case of the second separation step, multiple passes through the
hydrocyclone may be necessary to effect a suitable separation of
solvent from the water-wet bituminous material because of the
immiscibility between the solvent (i.e., paraffinic solvent) and
the water.
[0122] When solvent is added to a stream separated by the
hydrocyclone, such as in the case of adding additional solvent to
the solvent-wet bituminous material overflow described above, the
additional solvent can be obtained from a downstream hydrocyclone
separation. In this manner, the solvent flows countercurrent to the
solids for multiple washes and more efficient bitumen extraction
with higher bitumen loading into the solvent is obtained with each
subsequent hydro cyclone stage.
[0123] Any bitumen recovered from the above-described methods, such
as the bitumen content of the bitumen-enriched solvent phases, can
also undergo any type of upgrading processing known to those of
ordinary skill in the art. Upgrading of the bitumen can comprise
any processing that generally produces a stable liquid (i.e.,
synthetic crude oil) and any subsequent refinement of synthetic
crude oil into petroleum products. The process of upgrading bitumen
to synthetic crude oil can include any processes known to those of
ordinary skill in the art, such as heating or cracking the bitumen
to produce synthetic crude. The process of refining synthetic crude
can also include any processes known to those of ordinary skill in
the art, such as distillation, hydrocracking, hydrotreating, and
coking. The petroleum products produced by the upgrading process
are not limited, any may include petroleum, diesel fuel, asphalt
base, heating oil, kerosene, and liquefied petroleum gas.
[0124] Several advantages can be realized by using the methods and
systems described herein. Specifically, the use of a single solvent
where the solvent is paraffinic can provide numerous advantages
over other solvent bitumen extraction techniques, including those
techniques using more than one type of solvent. Firstly, the use of
paraffinic solvent can increase the throughput of the method by a
factor of 2 or greater. Improved throughput can be realized due to
the use of the lighter paraffinic solvent that is capable of
solvating the bitumen material faster than heavier solvents and
results in reduced viscosity dilbit, which can be recovered from
the solids easier. The paraffinic solvent can also advantageously
precipitate asphaltenes, further eliminating the heavy viscosity
component. In some instances, the paraffinic solvent causes the
asphaltenes to precipitate into the solids, and more specifically
onto the finer clays. The precipitated asphaltenes are captured by
finer clays while the dilbit passes through and out of the bitumen
material for successful bitumen extraction. The precipitation of
asphaltene can also be beneficial by allowing for the upgrading of
bitumen extracted in the dilbit using conventional upgrading
processing equipment (i.e., specialized upgrading equipment capable
of handling asphaltenes as well as bitumen is not required).
[0125] The systems and methods that use a single solvent instead of
two different types of solvents can also be advantageous from a
capital expenditure (CAPEX) perspective. Single solvent systems
typically only require a single distillation unit for the
separation and recovery of the single solvent. Single solvent
systems, including single solvent systems using a paraffinic
solvent, also tend to require smaller distillation units as
compared to when heavier solvents are used. Operating expenditures
(OPEX) are also reduced when using a single solvent system versus a
two solvent system. For example, lower heating duty is required for
removing a single, relatively light, solvent from the tailings.
Finally, environmental advantages can result from the single
solvent system. Carbon dioxide emissions and fugitive solvent loses
can be reduced when a single solvent system is used in lieu of a
system that uses two different types of solvents.
[0126] In view of the many possible embodiments to which the
principles of the disclosed invention may be applied, it should be
recognized that the illustrated embodiments are only preferred
examples of the invention and should not be taken as limiting the
scope of the invention. Rather, the scope of the invention is
defined by the following claims. We therefore claim as our
invention all that comes within the scope and spirit of these
claims.
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