U.S. patent application number 13/558041 was filed with the patent office on 2013-01-31 for methods and apparatus for bitumen extraction.
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 | 20130026077 13/558041 |
Document ID | / |
Family ID | 47596354 |
Filed Date | 2013-01-31 |
United States Patent
Application |
20130026077 |
Kind Code |
A1 |
Joshi; Mahendra ; et
al. |
January 31, 2013 |
Methods and Apparatus for Bitumen Extraction
Abstract
A bitumen extraction method can include the use of a two or more
mixing drums aligned in series for spraying solvent over bituminous
material and/or tailings loaded in the mixing drums while the
mixing drums rotate. Such mixing can result in the dissolution of
bitumen into the solvent, which then allows for the separation of a
"dilbit" stream from the bituminous material.
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: |
47596354 |
Appl. No.: |
13/558041 |
Filed: |
July 25, 2012 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61511894 |
Jul 26, 2011 |
|
|
|
61525557 |
Aug 19, 2011 |
|
|
|
Current U.S.
Class: |
208/390 ;
196/14.52 |
Current CPC
Class: |
C10G 1/045 20130101 |
Class at
Publication: |
208/390 ;
196/14.52 |
International
Class: |
C10G 1/04 20060101
C10G001/04 |
Claims
1. A bitumen extraction method comprising: feeding a first quantity
of bituminous material into a mixing drum; spraying a solvent over
the first quantity of bituminous material inside the mixing drum;
and separating the first quantity of bituminous material into a
dilbit stream and a tailings stream.
2. The method as recited in claim 1, wherein the solvent comprises
a paraffinic solvent.
3. The method as recited in claim 1, wherein the solvent comprises
pentane
4. The method as recited in claim 1, wherein the first quantity and
second quantity of bituminous material comprises oil sands.
5. The method as recited in claim 1, further comprising: removing
the dilbit stream and tailings stream from inside the mixing drum;
feeding a second quantity of bituminous material into the mixing
drum; and spraying the dilbit stream over the second quantity of
bituminous material inside the mixing drum.
6. The method as recited in claim 1, further comprising: rotating
the mixing drum while spraying solvent over the first quantity of
bituminous material.
7. The method as recited in claim 6, wherein the mixing drum is
rotated at a rate of less than 10 rpm.
8. The method as recited in claim 1, wherein solvent is sprayed
over the first quantity of bituminous material at a solvent:bitumen
ratio of from 0.5:1 to 3:1 on a volume basis.
9. The method as recited in claim 1, wherein separating the first
quantity of bituminous material into a dilbit stream and a tailings
stream comprises filtering the dilbit stream from the tailings
stream through a screen liner positioned inside of the mixing
drum.
10. The method as recited in claim 1, further comprising:
separating solid material from the dilbit stream.
11. The method as recited in claim 10, wherein separating solid
material from the dilbit stream comprises subjecting the dilbit
stream to a hydrocyclone, polymeric membrane, or centrifugal
separation unit.
12. The method as recited in claim 5, further comprising adding
solvent to the dilbit stream or removing bitumen from the dilbit
stream prior to spraying the dilbit stream over the second quantity
of bituminous material inside the mixing drum.
13. A bitumen extraction system comprising: a mixing drum
comprising a solvent inlet, a first dilbit outlet, and a first
tailings outlet; a first separation unit comprising a second dilbit
inlet in fluid communication with the first dilbit outlet, a
cleaned dilbit outlet, and a solid materials outlet; and a dilbit
storage unit comprising a cleaned dilbit inlet in fluid
communication with the cleaned dilbit outlet.
14. The bitumen extraction system as recited in claim 13, wherein
the cleaned dilbit outlet is in fluid communication with the
solvent inlet of the mixing drum.
15. The bitumen extraction system as recited in claim 13, wherein
the mixing drum further includes a liner screen positioned inside
of the mixing drum.
16. A bitumen extraction system comprising: a mixing drum
comprising a solvent inlet and a slurry outlet; a hydrocyclone
comprising a slurry inlet, a bitumen-depleted tailings outlet, and
a dilbit outlet, wherein the slurry inlet is in fluid communication
with the slurry inlet of the mixing drum and the dilbit outlet is
in fluid communication with the solvent inlet.
Description
[0001] This application claims priority to U.S. Provisional Patent
Application No. 61/511,894, filed Jul. 26, 2011, and U.S.
Provisional Patent Application No. 61/525,557, filed Aug. 19, 2011.
Each application is incorporated herein by reference in its
entirety.
BACKGROUND
[0002] Bituminous material such as oil sands typically include
sand, clay, water, and heavy crude oil. Many countries in the world
have large deposits of oil sands, including the United States,
Russia, and various countries in the Middle East. However, three
quarters of the world's reserves are found in Venezuela and Canada.
Oil sands may represent as much as two thirds of the world's total
petroleum resource, but are difficult to develop because of the
expense associated with recovering oil from oil sands.
[0003] Bitumen extraction from bituminous material such as oil sand
can be a very energy intensive process. In the extraction of
bitumen from bituminous material, the bituminous material is
typically mined, usually by a bucket wheel excavator of dragline,
and is then subjected to hot water extraction processing. In a
typical hot water extraction process, the bituminous material is
mixed with hot water such that the bitumen content of the
bituminous material floats as a froth and the solid matter content
of the bituminous material sinks, thereby making it possible to
skim off the froth for further separation and eventual refinement
to finished products. In some conventional hot water extraction
processes, 87% by weight of bitumen and diluent naphtha are
recovered from the bituminous material, with a loss of 13% by
weight being dumped with the waste solid matter. The disposal of
the solid matter involves passing the solid matter together with
accompanying hot water to a tailings pond. The hot water that is
lost can be at a temperature of approximately 185.degree. F. to
195.degree. F. The loss of this hot water considerably reduces the
overall plant thermodynamic efficiency as the beat loss must be
made up when reheating cold water for the hot water extraction
process.
[0004] In many hot water bitumen extraction processes, the tailings
produced by the process include solid matter, hot water, and
hydrocarbons not removed by the hot water process. These tailings
can be sluiced into retaining areas, such as large ponds formed
from dams or dykes built from tailings. When a first pond is
filled, a second dam is built in the middle of the mined out area
and this process of building dams and filling the ponds formed
between the dams is continued until the reserve of mineable oil
sands has been depleted. At this future time, most of the area of
the mined out acreage will be covered under almost a continuous
pond including water, oil emulsions, and clay fines gel.
Environmental authorities have determined that there has been and
will continue to be pollution impacts on the underground water
streams, surrounding lakes, and other fresh water bodies adjacent
to the mining areas. Under this tailings disposal system, little,
if any, of the mined out land can be reclaimed and put to useable
form.
SUMMARY
[0005] Disclosed below are representative embodiments that are not
intended to be limiting in any way. Instead, the present disclosure
is directed toward novel and nonobvious features, aspects, and
equivalents of the embodiments of the methods described below. The
disclosed features and aspects of the embodiments can be used alone
or in various novel and nonobvious combinations and
sub-combinations with one another.
[0006] In some embodiments, a bitumen extraction method includes a
step of feeding a first quantity of bituminous material into a
first mixing drum, a step of spraying first solvent over the first
quantity of bituminous material inside the first mixing drum, a
step of separating the first quantity of bituminous material into a
first dilbit stream and a first tailings stream, a step of feeding
the first tailings stream into a second mixing drum, a step of
spraying first solvent over the first tailings stream inside the
second mixing drum, and a step of separating the first tailings
stream into a second dilbit stream and a second tailings
stream.
[0007] In some embodiments, a bitumen extraction system includes a
first mixing drum having a first solvent inlet, a first dilbit
outlet, and a first tailings outlet; a first separation unit having
a second dilbit inlet in fluid communication with the first dilbit
outlet, a cleaned dilbit outlet, and a solid materials outlet; and
a second mixing drum having a first tailings inlet in fluid
communication with the first tailings outlet, a second dilbit
outlet in fluid communication with the first solvent inlet, and a
second tailings outlet.
[0008] In at least one or more embodiments, novel features and/or
advantages of the method can include use of a mixing drum to add
solvent to bituminous material, recover dilbit, and remove
tailings; use of multiple mixing drums in counterflow
configuration; use of one or more hydrocyclones to carry out
bitumen extraction; reducing or eliminating the need for hot water
in bitumen extraction processing; reducing or eliminating tailings
ponds containing oil emulsions and unstable clay fine gels;
improving the thermodynamic efficiency of the bitumen extraction
process; and improving the bitumen recovery efficiency to greater
than 90%.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] The preferred and other embodiments are disclosed in
association with the accompanying drawings in which:
[0010] FIG. 1 is a flow chart detailing a method for extracting
bitumen from bituminous material as disclosed herein;
[0011] FIG. 2 is a process flow diagram detailing a method for
extracting bitumen from bituminous material as disclosed
herein;
[0012] FIG. 3 is a flow chart detailing a method for extracting
bitumen from bituminous material as disclosed herein;
[0013] FIG. 4 is a process flow diagram detailing a method for
extracting bitumen from bituminous material as disclosed
herein;
[0014] FIG. 5 is a process flow diagram detailing a method for
extracting bitumen from bituminous material as disclosed
herein;
[0015] FIG. 6 is a process flow diagram detailing a method for
extracting bitumen from bituminous material as disclosed
herein;
[0016] FIG. 7 is a process flow diagram detailing a method for
extracting bitumen from bituminous material as disclosed
herein;
[0017] FIG. 8 is a flow chart detailing a method for extracting
bitumen from bituminous material as disclosed herein; and
[0018] FIG. 9 is a process flow diagram detailing a method for
extracting bitumen from bituminous material as disclosed
herein.
DETAILED DESCRIPTION
[0019] With reference to FIG. 1, a bitumen extraction method
according to some embodiments disclosed herein includes a step 100
of feeding bituminous material into a mixing drum, a step 110 of
spraying solvent over the bituminous material inside the mixing
drum, and a step 120 of separating the bituminous material into a
dilbit stream and a tailings stream.
[0020] The mixing drum used in step 100 can generally include any
type of drum suitable for use in mixing together bituminous
material and solvent. In some embodiments, the mixing drum is an
enclosed drum that includes one or more inlets for feeding
bituminous material and solvent into the drum and one or more
outlets for removing various mixtures of materials from the mixing
drum. The various inlets and outlets in the mixing drum can be
located throughout the mixing drum. The material of the mixing drum
is not limited, and may include materials that are generally
impermeable and corrosion resistant. In some embodiments, the
mixing drum has a generally cylindrical shape, although other
shapes may be used. The mixing drum can also vary in size and
dimensions, and the size and dimensions of the drum are generally
selected based on the amount of bituminous material to be handled
inside the mixing drum and the bituminous material characteristics
(i.e. particle size, dissolution rate etc.).
[0021] In some embodiments, the mixing drum is a
cylindrically-shaped drum oriented such that the axis of the
cylindrically-shaped drum is generally horizontal. The
cylindrically-shaped drum can also be slanted such that one end is
higher than the other, or positioned in a generally vertical
position. However for purposes of this discussion, the drum will be
described in the scenario where the axis of the drum is generally
horizontal.
[0022] The cylindrical drum can include one or more inlets located
at various locations throughout the drum for feeding bituminous
material inside of the drum. In some embodiments, the inlets are
located proximate one end of the drum for the introduction of
bituminous material into the drum. The inlets can be located around
the circumference of the drum near one end of the drum, in the end
wall of the drum (i.e., the wall perpendicular to the ground when
the axis of the drum is positioned horizontally), or a combination
of both.
[0023] The drum can also include inlets for providing solvent to
the interior of the drum. The inlets for adding solvent into the
drum can be located anywhere about the drum, such as those
locations described above with respect to inlets for feeding
bituminous material inside of the drum. In some embodiments, inlets
are provided at various locations throughout the drum such that
solvent can be added into the drum at various locations throughout
the drum.
[0024] In some embodiments, the various inlets and outlets included
in the mixing drum can be sealed when mixing occurs within the
mixing drum. Sealing of the inlets and outlet can help to ensure
that materials inside the mixing drum do not leak out of the mixing
drum, and also that any gases or vapors produced inside of the
mixing drum do not leak out of the mixing drum.
[0025] In some embodiments, one or more spray bars are positioned
within the drum to provide solvent to the interior of the drum. In
such embodiments, the spray bar passes through an end wall of the
drum and solvent enters the interior of the drum by passing through
the spray bar and into the drum. The spray bar can include numerous
nozzles along its length where solvent is sprayed into the interior
of the drum. In some embodiments, the spray bar is oriented
generally parallel to the axis of the cylindrical drum, although
other orientations can be used.
[0026] In some embodiments, the interior walls of the mixing drum
include a liner that protects the shell of the mixing drum. This
liner can cover the entirety of the interior wall of the mixing
drum or only portions of the interior of the mixing drum. Any
suitable liner material can be used, and in some embodiments, the
liner material is alloy steel or a thick layer of rubber or any
other elastomer that is compatible with the selected solvent. This
liner material prevents wear to the mixing drum. Any manner of
securing the liner to the interior walls of the mixing drum can be
used, and in some embodiments, the liners are bolted securely to
the mixing drums with specially designed washers that prevent drum
leakage.
[0027] The cylindrical drum can also include a mechanism for
rotating the drum, including rotating the drum about its axis. Any
manner of rotating the drum can be used, including hydraulic motors
and tire and trunnion mechanisms. The speed at which the drum can
be rotated can vary over a wide range of speeds.
[0028] The cylindrical drum can also include a screen liner for
facilitating the separation of materials inside the drum. The
screen liner can have any suitable shape, including a generally
cylindrical shape. When the screen liner has a cylindrical shape,
the diameter of the screen liner can be smaller than the diameter
of the mixing drum such that the screen liner is positioned inside
of and coaxial with. the mixing drum. In some embodiments, the
screen liner can include a plurality of coaxially aligned screens,
with each screen having a different mesh size. In this manner, the
multiple screen liner can effect a coarse and fine separation of
materials inside the mixing drum.
[0029] The screen liner can extend along the entire length of the
drum or only a portion of the length of the drum. In some
embodiments, the screen liner is located at only one end of the
drum, and preferably the end of the drum opposite inlets for
introducing bituminous material into the drum. In some embodiments,
the screen liner has a length that is more than half the length of
the mixing drum. For example, the mixing drum can have an overall
length of 22 meters, with the screen liner having a length of 12
meters. In such a configuration, mixing occurs in the mixing drum
along the first 10 meters of the mixing drum, and separation occurs
along the last 12 meters of the mixing drum. In this manner, mixing
between bituminous material and solvent can take place along a
first portion of the length of the drum while separation occurs at
the end of the drum, after substantial mixing has taken place.
[0030] The mesh size of the screen liner can vary and be adjusted
depending on the sizes of the material to be separated. In
application, the screen effectively creates an area between the
liner and the drum where material that passes through the liner can
collect and be removed from the drum via a first outlet, and an
area within the screen liner where bituminous material having
bitumen extracted therefrom (i.e., tailings) remains. The material
that cannot pass through the liner remains within this inner area
can be removed from the drum via a second (i.e., tailings) outlet.
The first outlet is therefore positioned along the drum in a
position that communicates with the area between the liner and the
drum. In some embodiments, this location will be along the
circumference of the drum. Similarly, the second outlet can be
positioned at a location that is in communication with the interior
of the screen liner. In some embodiments, this location will be on
an end wall of the drum. In some embodiments, the mesh size of the
screen liner is from between 40 mesh and 200 mesh. The cylindrical
drum can further include lifting shelves (i.e., lifters) that help
to promote mixing within the drum when the drum rotates. The height
of each lifting shelf generally extends radially inward from the
interior wall of the mixing drum, while the length of each lifting
shelf is generally oriented parallel to the axis of the drum. In
this manner, the lifting shelves carry a portion of the material
inside of the drum up along the wall of the drum as the drum
rotates. Eventually the lifting shelves rotate to a position where
they slant downwardly and the lifted material falls back down
towards the bottom of the drum. This movement of the material helps
to promote mixing as discussed in greater detail below. The lifting
shelves can be made from any suitable material, including steel,
rubber, or other elastomers compatible with the solvents in use.
Each lifting shelf can have a length that extends the entire length
of the drum or the lifting shelves can lengths that are shorter
than the length of the drum. When in shorter segments, various
lifting shelves along the length of the drum can be offset from
other lifting shelves located at other positions along the length
of the drum.
[0031] The height of each lifting shelf can be any suitable height
and the heights of the lifting shelves can be the same or varying
throughout the drum. In some embodiments, the placement and height
of each lifting shelf can be adjusted in order to vary the
residence time of the material inside of the drum. Longer residence
times can lead to more nixing, and therefore adjustments can be
made to the placement and height of the lifting shelves used in
order to increase or decrease residence time. In some embodiments,
the lifting shelves can be in the form a flute, such as commonly
used in a cement mixer, to gently knead and mix the slurry without
creating high shear.
[0032] Retention rings may also be included within the drum to
further vary residence time. One or more retention rings can be
placed axially along the length of the drum and will slow the
movement of material from one end of the drum to the other, thereby
increasing residence time and promoting further mixing between
materials.
[0033] In some embodiments, the mixing drum may also include a
heating mechanism for heating the material inside of the mixing
drum. Any suitable type of heater can be used to accomplish the
heating of material inside the mixing drum. In some embodiments,
the mixing drum includes direct or indirect heating via, for
example, a hot water or steam jacket surrounding a portion or all
of the exterior of the mixing drum to thereby provide heat from the
hot water or steam passing through the jacket through the walls of
the mixing drum and to the material inside of the mixing drum. Use
of a heater with the mixing drum can be especially preferable when
the materials inside of the mixing drum are cold when transported
into the mixing drum. For example, when the bituminous material
transported into the mixing drum is mined Alberta oil sands, the
temperature of the bituminous material is very cold. In some
embodiments, the heater used in conjunction with the mixing drum is
capable of heating the materials inside of the mixing drum to a
temperature between 20.degree. C. and 75.degree. C. The heater may
be incorporated with the mixing drum to create a heated mixing drum
(e.g., steam jacket) or the heater may be an independent device to
raise the temperature of the bituminous material and/or solvent
prior to entering the mixing drum. In some embodiments the heater
may be upstream in the process flow sheet either before a primary
crusher or incorporated within the primary crushing stage.
[0034] In some embodiments, the mixing drum is a trommel or a
pulper. Trommels or pulpers generally include the closed drum
configuration used for the mixing drum and can further include the
internal screen mechanism for separating various materials inside
of the drum. Any trommel or pulper suitable for use in mixing
together and separating different materials can be used.
[0035] The bituminous material fed into the mixing drum can include
any material that includes a bitumen content. In some embodiments,
the bituminous material is oil sands or tar sands. The source of
bituminous material is also not limited, and can include bituminous
material obtained from natural deposits (such as by mining) or
material that is produced by other processes (such as distillation
bottoms produced by a distillation column). The bitumen content of
the bituminous material can vary across a wide range and is
generally dictated by the quality of the bituminous material being
processed. For example, high quality bituminous material can
include greater than 20% by weight bitumen, while lower quality
bituminous material can include less than 5% by weight bitumen.
Other components of the bituminous material can include, but is not
limited to, water, clay, and sand.
[0036] Any suitable manner for feeding the bituminous material into
the mixing drum can be used. As mentioned above, the bituminous
material can be fed into the mixing drum through one or more inlets
located at various locations throughout the mixing drum. The
bituminous material can be transported to the mixing drum inlet by
any manner, including through the use of conveyor belts, chutes,
hoppers, and screw feeders. In some embodiments, the bituminous
material is transported into the mixing drum as the mixing drum is
rotating about its axis.
[0037] In some embodiments, the bituminous material may be broken
into smaller pieces prior to introduction into the mixing drum. Any
manner of breaking up the large pieces of bituminous material may
be used, including the use of a traditional breaker, sizer, or
crusher. In some embodiments, the bituminous material is broken up
into pieces having a size of less than 3 inches or, in some cases,
less than 1 inch.
[0038] In some embodiments, solvent is mixed with the bituminous
material prior to and/or during the process of breaking up larger
pieces of bituminous material into smaller pieces. The solvent used
during the breaking/crushing step can be the same solvent used in
subsequent solvent extraction steps. In some embodiments, the
solvent is a paraffinic solvent, such as pentane. The solvent used
in the breaking/crushing step can be heated, such as to within a
range of from 50.degree. F. to 100.degree. F. Additionally, the
apparatus used to crush the bituminous material can be heated using
an internal or external heating mechanism.
[0039] Adding the solvent to the bituminous material can be carried
out in any suitable manner that wets the bituminous material with
solvent and begins the process of dissolving bitumen in the
solvent. In some embodiments, the solvent is sprayed over the
bituminous material. For example, a crushing apparatus can be
configured with one or more spray nozzles for spraying solvent over
the bituminous material before and/or as the bituminous material
passes through the crushing mechanism (e.g., a crushing roller). In
other embodiments, the solvent and the bituminous material can be
mixed together to form solvent-wet bituminous material prior to
being introduced into a crushing apparatus. In other words, a
mixing vessel separate from the crushing apparatus can be provided
that prepares the solvent-wet bituminous material prior to
introducing the bituminous material into the crushing apparatus.
Any suitable mixing vessel, including a mixing vessel having mixing
blades, can be used. Adding solvent to the bituminous material can
also be carried out on the conveyors, buckets, or chutes used to
transport the bituminous material to the crushing apparatus.
[0040] Any suitable amount of solvent can be added to the
bituminous material. In some embodiments, the amount of solvent
added to the bituminous material is from 0.5 to 4 times the amount
of bitumen in the bituminous material on a v/v basis.
[0041] The solvent-wet bituminous material is subsequently crushed
in order to reduce the size of clumps of bituminous material and
assist with further mixing between the solvent and the bituminous
material. Any manner of crushing the solvent-wet bituminous
material can be used, including the use of crushing apparatus known
to those of ordinary skill in the art. Exemplary crushing
mechanisms include, but are not limited to, crushing rollers or
sizers.
[0042] In some embodiments, the solvent-wet bituminous material is
crushed by passing the solvent-wet bituminous material through
crushing rollers. The crushing rollers can be individually driven
by electrical motors, gear motors, or with coupling and gears
counter rotating via V-belts. Even distribution of the solvent-wet
bituminous material across the entire length of the crushing
rollers or other crushing mechanisms, the use of a favorable angle
of entry, and in the case of crusher rollers, adjusting the speed
and diameter of the crusher rollers, can help to ensure efficient
crushing of the solvent-wet bituminous material and reduced wear
and tear on the crushing mechanism.
[0043] Crushing rollers used to crush the solvent-wet bituminous
material can also be internally heated to help improve
disaggregation. Any suitable manner of internally heating the
crushing rollers can used, such as through the use of steam, hot
water, or electricity. The crusher rollers can be heated to any
suitable temperature for improving disaggregation. In some
embodiments, the crusher rollers are heated to a temperature below
the boiling point temperature of the solvent, such as from
50.degree. F. to 100.degree. F.
[0044] In some embodiments, the crusher rollers are provided with
perforations or holes that deliver solvent to the surface of the
crusher rollers. Providing solvent in this manner can create a wet
film on the surface of the crusher rollers that further reduced
mechanical wear and tear on the surface of the crusher rollers. The
solvent delivered through these holes can be heated and can be
delivered to the surface of the crusher rollers continuously or
intermittently.
[0045] In some embodiments, conveyors can be used to deliver
bituminous material into the crushing apparatus. In instances where
the bituminous material is wetted with solvent prior to being
introduced into the crushing apparatus, the conveyors can be used
to deliver solvent-wet bituminous material into the crushing
apparatus. In instances where the mechanism for adding solvent to
the bituminous material is incorporated into the crushing apparatus
(e.g. spray nozzles located within the crushing apparatus and
upstream of the crushing mechanism), the conveyors can be used to
deliver dry bituminous material into the crushing apparatus.
[0046] In some embodiments, the steps of adding solvent to the
bituminous material and crushing the solvent-wet bituminous
material are repeated. Additional solvent can be added to the
crushed solvent-wet bituminous material produced by the first
solvent addition step and the first crushing step, followed by
subjecting the crushed solvent-wet bituminous material to a second
crushing step. Following the one or more wetting and crushing
steps, the bituminous material can be fed into the mixing drum.
[0047] Once bituminous material has been fed into the mixing drum,
a step 110 of spraying a solvent over the bituminous material
inside the mixing drum takes place. The solvent wets the bituminous
material and forms a slurry of material inside the mixing drum. One
aim of adding solvent to the bituminous material inside of the drum
is to promote the dissolution of bitumen into the solvent to
thereby extract it from the bituminous material. The rotating
mixing drum, lifting shelves, retention rings, heat and other
mechanisms can be used to promote the mixing between the bituminous
material and the solvent and the dissolution of the bitumen in the
solvent. Eventually, a phase of bitumen diluted in solvent, also
referred to as "dilbit," and a phase of bitumen-depleted tailings
will result from the mixing of solvent and bituminous material
inside of the mixing drum.
[0048] Any solvent capable of dissolving all or a specific part of
the bitumen can be sprayed over the bituminous material inside of
the mixing drum. Exemplary solvent suitable for use in step 110
include paraffinic solvents (such as propane and pentane), naphtha,
bio-diesel, methanol, and ethanol. In some embodiments, the solvent
is "dilbit," i.e., bitumen diluted in a solvent. Any of these
solvents mentioned above may serve as the solvent component in the
"dilbit." In some embodiments where "dilbit" is used as the solvent
sprayed over the bituminous material, the "dilbit" is from about
30% to about 80% solvent by volume.
[0049] In some embodiments, the amount of solvent sprayed over the
bituminous material is based on a ratio of solvent to bitumen
content in the bituminous material. Accordingly, the amount of
solvent used can vary based on the quality of the bituminous
material (i.e., the bitumen content of the bituminous material and
the pore size in the bitumen) and the solvent density or solvency
power. In some embodiments, the solvent to bitumen ratio used in
the spraying step 110 is from about 0.5:1 to 4:1 on a volume basis.
Using a solvent to bitumen ratio within this range can help to
ensure that enough solvent is sprayed over the bituminous material
to dissolve a substantial portion of the bitumen content of the
bituminous material.
[0050] When spraying solvent into the mixing drum containing
bituminous material therein, a volume of the mixing drum will be
occupied by the resulting slurry. In some embodiments, the amount
of bituminous material and solvent into the mixing drum at one time
is controlled in order to ensure that no greater than or no less
than a specified percentage of the internal volume mixing drum is
occupied. Over or under filling the mixing drum can negatively
impact the mixing of the solvent and bituminous material and the
dissolution of bitumen into the solvent. In some embodiments, from
20% to 60% of the volume inside the mixing drum is occupied by
bituminous material and solvent.
[0051] As described above, the effect of spraying the solvent over
the bituminous material is to create a slurry of material inside
the mixing drum that can include two phases. The first phase is
bitumen diluted in solvent ("dilbit"). The second phase is
bitumen-depleted tailings. The bitumen-depleted tailings will
generally include solvent, water, sand, clay, and a relatively
small amount of bitumen that was not dissolved by the solvent. In
some embodiments, the bitumen-depleted tailings can also include
precipitated asphaltenes. Some or all of the bitumen content of the
bitumen-depleted tailings can include bitumen that is occluded on
the inert material of the tailings. While the rotation of the
mixing drum can work to remove some of the bitumen that is stuck to
the inert material (e.g., due to contact between slurry falling
from the lifting shelves with slurry residing at the bottom of the
mixing drum), the rotation of the drum typically does not remove
all of the occluded bitumen from the inert material. Accordingly, a
relatively small amount of bitumen remains with the
bitumen-depleted tailings.
[0052] The rotation of the drum while the solvent is sprayed over
the bituminous material can be any suitable speed that helps to
promote mixing. of the solvent and the bituminous mater and the
create dilbit. In some embodiments, the rotational speed is kept
relatively slow in order to avoid the dispersion of the clay
component of the bituminous material. High rotational speeds cause
clay dispersion because of high agitation and attrition breaking up
clay lenses. Clay dispersion is undesirable because clays can
become suspended in the dilbit and affect dilbit quality, requiring
additional clay removal steps. In some embodiments, the rotational
speed of the mixing drum is kept to less than 10 rpm in order to
avoid clay dispersion, although higher rotational speeds can be
used.
[0053] In some embodiments, the rotation of the mixing drum
continues after spraying solvent over the bituminous material
inside the mixing drum has ceased. Continuing to rotate the mixing
drum during and after the solvent is sprayed over the bituminous
material inside the mixing drum promotes mixing of the slurry of
bituminous material and solvent and the dissolution of the bitumen
content of the bituminous material into the solvent as described
above. In some embodiments, the mixing of the slurry by the
continued rotation of the mixing drum during and after solvent is
sprayed over the bituminous material can continue for a period of
time sufficient to ensure that bitumen dissolution occurs and a
dilbit phase is created. The specific period of time of mixing can
vary based on varying factors, including the bitumen content of the
bituminous material and the amount of solvent sprayed over the
bituminous material. In practice, the mixing drum may be a
continuously operated device with a constant feed of bituminous
material and solvent to one end and a continuous discharge of dilbt
and bitumen depleted material at the other end, thus providing a
residence time in the drum sufficient for dissolution and
separation to occur.
[0054] The injection of solvent into the mixing drum and the
subsequent mixing of the solvent and the bituminous material to
create dilbit can, in some embodiments, create a need for the
mixing drum to include a solvent vapor recovery system. A solvent
recovery system can be necessary due to the volatility of some of
the solvents suitable for use in the methods described herein.
Despite being injected into the mixing drum as a liquid, portions
of such volatile solvents may convert to a vapor phase once inside
the mixing drum, and therefore require venting from inside the
mixing drum. Any solvent vapor recovery system suitable for use
with a mixing drum can be used, including one or more solvent vents
on the mixing drum and a solvent vapor collection vessel connected
to the one or more solvent vents.
[0055] In some embodiments, the mixing drum can be a pressurized
mixing drum. A pressurized mixing drum may be necessary in
instances where the solvent injected into the mixing drum will not
remain in a liquid state unless the mixing drum is pressurized. For
example, the mixing drum can be a pressurized mixing drum when
propane or butane is used in order to keep the propane and/or
butane in a liquid state inside the mixing drum. Any mechanism
suitable for pressurizing the mixing drum can be used.
[0056] In some embodiments, the solvent added to the bitumen
material in the mixing drum can undergo pretreatment, such as
heating the solvent. Additionally, heat can be applied to the
bitumen material and solvent being mixed inside the mixing drum. In
some embodiments, the heating of the mixing drum is accomplished by
a heating source external to the mixing drum. The heating can be
via indirect heating, including through the use of steam via a
steam jacket on the mixing drum or direct steam injection.
[0057] The mixture of bituminous material and solvent and the
creation of a slurry having dilbit and bitumen-depleted tailings is
followed by a step 120 of separating the dilbit from the bitumen
depleted tailings. Any technique capable of separating the dilbit
from the slurry can be used (e.g., hydrocyclones, thickeners,
clarifiers or filtration devices). As mentioned above, a liner
screen located within the mixing drum can be used in some
embodiments. The liner screen, such as a coaxial liner screen
position at one end of the mixing drum, can have a mesh size that
is large enough to allow the dilbit to pass through but that is
small enough to keep the bitumen-depleted tailings within the liner
screen. As the dilbit passes through the liner screen, the dilbit
can be routed to an outlet in the mixing drum so that it can be
removed from the mixing drum and used in subsequent steps of the
process. Similarly, the bitumen-depleted tailings that remain
within the liner screen can be transported out of the mixing drum
via an outlet in the mixing drum. Once removed from the mixing
drum, the bitumen-depleted tailings can be subjected to further
processing, such as further contacting with solvent for additional
bitumen recovery or solvent recovery.
[0058] Based on the mixing and separation steps, the dilbit
obtained from the mixing drum can typically include from about 30
to about 60 wt % bitumen and from about 40 to about 70 wt %
solvent. Relatively small amounts of solid material, such as sand,
may also be included in the dilbit. In some embodiments, the dilbit
may include from about 0 to about 3 wt % solid material. With
respect to the bitumen-depleted tailings resulting from the mixing
and separating steps, the bitumen-depleted tailings generally
include from about 50 to about 75 wt % inert materials (such as
clay and sand), from about 0 to about 5 wt % water, from about 25
to about 40 wt % solvent, and from about 3 to about 15 wt %
bitumen.
[0059] Due to the undesirable presence of solid material such as
fine solids or clays in the dilbit, additional steps can be taken
to remove the solid material and form an essentially pure dilbit
material. Any technique that removes solid material from the dilbit
can be used. In some embodiments, a hydrocyclone, centrifuge,
desander, switchable filter tube, filter, polymeric membrane, or
screen is used to remove the solid material from the dilbit.
Preferably, the hydrocyclone, centrifuge, filter, polymeric
membrane, screen, etc., removes 95% or more of the solid material
in the dilbit, although removal of solid material down to any level
suitable for subsequent processing is also acceptable. The solid
material, which will include mostly sand particles, can then be
disposed of, added back with the bitumen-depleted tailings leaving
the mixing drum, or be recycled back into the mixing drum in the
same manner as bituminous material is fed into the mixing drum in
order to attempt to recover any remaining bitumen that may be
occluded on the solid material. When solid material is fed back
into the mixing drum, the solid material undergoes similar or
identical processing steps as those described above with respect to
bituminous material.
[0060] The purified dilbit obtained after solid material is removed
therefrom can be subjected to a variety of further processing
steps. In some embodiments, the dilbit is transported to a storage
tank where it can be added to other dilbit already collected. In
some embodiments, dilbit collected in the storage tank can be used
as the solvent sprayed over the bituminous material in step 110. In
order to ensure that the dilbit used as solvent in step 110 has a
desirable bitumen and solvent content, additional solvent can be
added to the storage tank or bitumen can be removed from the
storage tank. For example, if the dilbit contained in the storage
tank includes 60 wt % solvent and 40 wt % bitumen but a 70% wt
solvent and 30 wt % bitumen content is desired when the dilbit is
used as solvent sprayed over the bituminous material in the mixing
drum, then solvent can be added to the storage tank to get the
dilbit in the storage tank to the correct composition. The solvent
that is added to the storage tank can be any of the solvents
discussed above. Any suitable manner of removing bitumen from the
storage tank can be used, such as by distillation, flashing,
gravity separation, and filtration with polymeric membranes.
[0061] In embodiments where the dilbit is used as a solvent and
sprayed over bituminous material transported into the mixing drum
in step 110, the dilbit can optionally be heated by a heating
mechanism prior to being sprayed over the bituminous material. In
some embodiments and depending on the boiling point of the solvent,
the dilbit is heated to a temperature between 20.degree. C. and
120.degree. C. Any type of heater can be used to heat the dilbit to
a temperature within this range, including a heat exchanger.
[0062] In instances where the solvent used in step 110 is
preferably not dilbit, the dilbit in the storage tank can be
processed to separate the bitumen from the solvent, at which point
the separated solvent can be used as the solvent sprayed over the
bituminous material in step 110. The separated bitumen can then be
transported to further processing apparatus, such as apparatus used
to upgrade the bitumen into commercially useful lighter
hydrocarbons. Any manner of separating the dilbit into solvent and
bitumen can be used, including the use of a froth tank or
distillation units.
[0063] As noted above, the bitumen-depleted tailings resulting from
the mixing and separating steps can include a residual amount of
solvent. Therefore, in some embodiments, the bitumen-depleted
tailings are treated for solvent removal and recovery. Any methods
suitable for removing solvent from tailings can be used. In some
embodiments, treatment for solvent removal includes washing the
tailings with the same solvent that is used in the initial mixing
stage. This washing can take place in a secondary mixing drum
similar or identical to the one or more primary mixing drums
described above and used to mix bituminous material and solvent. In
some embodiments, the additional solvent used in the washing stage
is in the vapor phase or is supercritical solvent. This can help to
minimize the amount of solvent remaining in the tailings after the
washing stage. The washing with additional solvent can be carried
out in one or more washing stages. While the washing with
additional solvent can remove the majority of the solvent in the
tailings, some trace amounts of additional solvent may remain in
the tailings. Accordingly, the tailings can be further processed
for further solvent recovery, such as via a column, filtration
device, or by drying or flashing to remove the solvent prior to
discharge of the tailings as a final waste.
[0064] In some embodiments, the washing of the bitumen-depleted
tailings with additional solvent can be carried out in the same
mixing drum used for spraying the initial bituminous material with
the solvent. In such embodiments, the mixing drum will typically
include a screen liner so that separation of the dilbit and the
bitumen-depleted tailings can be carried out within the mixing
drum. In practice, washing with a additional solvent can begin by
terminating the spraying of solvent into the mixing drum and
removing the dilbit separated from the bitumen-depleted tailings
via the screen liner from the mixing drum. The bitumen-depleted
tailings can remain in the mixing drum. Additional solvent is then
added to the bitumen-depleted tailings inside the mixing drum,
including adding vaporous or supercritical solvent to the tailings.
Rotation of the drum to promote mixing between the tailings and the
additional solvent can be carried out in a similar or identical
fashion as described above. The additional solvent displaces the
solvent out of the tailings, where it can then pass through the
screen liner located inside the mixing drum to effect separation of
the solvent from the tailings. The washed tailings, which now
include some trace amounts of additional solvent, remain within the
screen liner and can be processed to remove trace additional
solvent from the tailings, including by removing the tailings from
the mixing drum and heating the tailings to the point of
evaporating the trace additional solvent.
[0065] In embodiments where the mixing drum does not include a
screen liner or other internal separation device, the slurry can be
removed from the mixing drum and then be subjected to separation of
the dilbit from the bitumen-depleted tailings. The bitumen-depleted
tailings can then be transported back into the same mixing drum
used for the first solvent spraying step and be subjected to
further solvent washing as described above. Any suitable apparatus
can be used to separate the slurry, including but not limited to, a
thickener. When a thickener is used, the slurry is received by the
thickener, and the thickener separates the slurry such that it
produces a stream of dilbit and a stream of bitumen-depleted
tailings.
[0066] FIG. 2 illustrates a process diagram of embodiments
described above. Bituminous material 200 is run through a crusher
210 to reduce the size of larger pieces of the bituminous material
200. Once crushed, the bituminous material 200 is transported to a
mixing drum 220 that includes a spray bar 225. As the bituminous
material 200 enters the mixing drum 220, solvent is sprayed over
the bituminous material 200 via the spray bar 225. The mixing drum
220 rotates during the spraying and a slurry is formed. The slurry
generally contains a bitumen-enriched solvent phase and a
bitumen-depleted tailings phase. A screen liner 226 inside of the
mixing drum 220 works to separate the bitumen-enriched solvent
phase from the bitumen-depleted tailings phase 235. The bitumen
enriched solvent phase 230 leaves the mixing drum and is sent to a
separation unit 240, such as a hydrocyclone. The separation unit
240 works to separate any solid material from the bitumen-enriched
solvent phase 230. Accordingly, the separation unit 240 creates a
purified dilbit stream 250 and a solid materials stream 260. The
solid materials stream 260 is routed back to the mixing drum 226 to
undergo further mixing with solvent inside the mixing drum 220.
Alternatively, the solid materials stream 260 can be added back
with the bitumen-depleted tailings phase 235. The purified dilbit
stream 250 is sent to a storage tank 270 where several different
processing steps can occur. In some instances, the dilbit stream
250 will be suitable for use as solvent that is sprayed over
bituminous material inside of the mixing drum 220. In some
instances, the amount of solvent and bitumen in the dilbit stream
250 will need to be adjusted, at which point bitumen 280 can be
removed from the dilbit 250 in the storage tank 270 or solvent 290
can be added to the storage tank 270. In still other instances, the
dilbit 250 will be separated into solvent and bitumen 280, with the
solvent being sprayed over further bituminous material inside of
the mixing drum 250 and the bitumen 280 being sent to an
upgrader.
[0067] In some embodiments, a method of extracting bitumen from
bituminous material utilizes two or more mixing drums aligned in
series. With reference to FIG. 3, the method can include a step 300
of feeding a first quantity of bituminous material into a first
mixing drum, a step 310 of spraying solvent over the first quantity
of bituminous material inside the first mixing drum, a step 320 of
separating the first quantity of bituminous material into a first
dilbit stream and a first tailings stream, a step 330 of feeding
the first tailings stream into a second mixing drum, a step 340 of
spraying solvent over the first tailings stream inside the second
mixing drum, a step 350 of separating the first tailings stream
into a second dilbit stream and a second tailings stream, a step
360 of feeding a second quantity of bituminous material into the
first mixing drum, and a step 370 of spraying the second dilbit
stream over the second quantity of bituminous material inside the
first mixing drum.
[0068] In step 300, a first quantity of bituminous material is fed
into a first mixing drum. The bituminous material and the mixing
drum used in step 300 may be similar or identical to the bituminous
material and mixing drum described in greater detail above.
Similarly, the manner of feeding the bituminous material into the
first mixing drum can be similar or identical to the feeding step
100 described in greater detail above. The first quantity of
bituminous material used in step 300 can be any quantity that can
be processed in the mixing drum. Accordingly, the size of the
mixing drum can impact the size of the first quantity of bituminous
material.
[0069] In step 310, a solvent is sprayed over the first quantity of
bituminous material inside the first mixing drum. Step 310 can be
similar or identical to step 110 described in greater detail above,
including the type and amount of solvent used, the rotation of the
mixing drum during spraying, and the delivery of solvent via a
spray bar extending through the mixing drum. Similarly, the result
of step 310 is similar or identical to step 110 described in
greater detail above. Mixing the solvent and bituminous material
results in the formation of a slurry containing bitumen dissolved
in solvent and solvent-wet inert material (that may or may not have
some bitumen occluded thereon). In some embodiments, the solvent
sprayed over the bituminous material in step 310 is paraffinic
solvent.
[0070] In step 320, the first quantity of bituminous material,
which is now solvent wet and in the form of the previously
described slurry, is separated into a first dilbit stream and a
first tailings stream. The manner of separating the slurry into
these two components is similar or identical to the separation
methods described above in connection with step 120. Thus, in some
embodiments, the mixing drum includes a liner screen that filters
the dilbit away from the tailings. Alternatively, the slurry is
removed from the mixing drum and separated external to the mixing
drum, such as in a thickener or hydrocyclone. The separated first
dilbit stream and the first tailings stream can be similar or
identical to the dilbit and tailings described above in step 120.
Accordingly, the first dilbit stream can include primarily bitumen
and solvent and the first tailings stream can include solvent,
water, and inert materials, such as sand and clay. As also
mentioned above in the discussion of step 120, the first dilbit
stream can further include a relatively small amount of solid
particles and the first tailings stream can include a bitumen
content, including bitumen that remains occluded on the inert
material and/or bitumen that is dissolved in solvent that remains
with the tailings.
[0071] In step 330, the first tailings stream produced from the
separation step 320 is transported and fed in to a second mixing
drum. The first tailings stream can be transported to the second
mixing drum in any suitable manner, including through the use of
conveyors, chutes, or screw feeders. The second mixing drum can be
similar or identical to the first mixing drum. While the shape and
orientation of the second mixing drum is not limited, in some
embodiments the second mixing drum is a horizontally positioned
cylindrical drum. As with the previously described mixing drum, the
second mixing drum can be capable of rotating about its axis to
promote mixing between the first tailings stream and solvent
injected therein, and can also include a screen liner for
separating materials after mixing. The size of the second mixing
drum is also not limited, and will generally be selected based on
the amount of tailings to be processed inside of the second mixing
drum. In some embodiments, the second mixing drum is a trommel or
pulper as, described in greater detail above.
[0072] Alternatively, step 330 can be omitted. In such embodiments,
the first tailings stream can remain in the first mixing drum, and
further solvent processing of the tailings can be carried out in
the same mixing drum used to spray first solvent over the
bituminous material. If the first mixing drum does not include a
mechanism for separating the slurry into a dilbit stream and a
tailings stream, the slurry can be temporarily removed from the
mixing drum to separate the slurry into a dilbit stream and a
tailings stream, after which the tailings stream can be transported
back into the first mixing drum. Any suitable method for separating
the slurry external to the mixing drum can be used, including using
a filter press or screening mechanism.
[0073] In step 340, solvent is sprayed over the first tailings
stream inside the second mixing drum (or, in embodiments where step
330 is omitted, in the first mixing drum). The manner in which the
solvent is sprayed over the first tailings stream can be similar or
identical to the spraying step 110 described in greater detail
above. Thus, in some embodiments, the solvent is sprayed over the
first tailings stream using a spray bar that extends into the
second mixing drum. Any solvent described here can be used,
although in some embodiments, the solvent is dilbit. When dilbit is
used as the solvent, the amount of dilbit used in step 340 can be
based on the same ratios discussed above in step 110. More
specifically, the amount of dilbit used in step 340 can be based on
the bitumen content of the tailings, and range from a solvent
(i.e., dilbit) to bitumen ratio of from 0.5:1 to 9:1 on a volume
basis.
[0074] When dilbit is used as the solvent in step 340, the source
of the dilbit is not limited, although in some preferred
embodiments, the source of the dilbit is downstream processing
steps. More specifically, and as described in greater detail below,
the dilbit may be originated from an additional mixing drum located
downstream from and connected in series with the first and second
mixing drums. For example, where a third mixing drum is connected
in series with the first and second mixing drum, the third mixing
drum can receive tailings produced from the second mixing drum.
Treatment of these tailings in the third mixing drum with solvent
will produce dilbit, which once separated and removed from the
third mixing drum, can be recycled back and used as the dilbit
sprayed over the tailings in the second mixing drum. Generally
speaking, dilbit produced from a mixing drum can be used as the
solvent in the mixing drum immediately prior in a series of mixing
drums.
[0075] In step 350, the slurry produced inside of the second mixing
drum by virtue of spraying solvent over the first stream of
tailings is separated into a second dilbit stream and a second
tailings stream. This separation step can be similar or identical
to the separation steps 330 and 120 discussed in greater detail
above. Accordingly, in some embodiments, the separation is carried
out by virtue of a liner screen inside of the second mixing drum
that filters the second dilbit stream from the second tailings
stream, while in other embodiments, the separation is carried out
in a separation vessel (such as a thickener or hydrocyclone)
located external to the second mixing drum. The second dilbit
stream and second tailings stream produced by the separation step
can be similar or identical in composition to the dilbit and
tailings streams described in greater detail above. In some
embodiments, the dilbit and tailings streams are lower in bitumen
content then the dilbit and tailings stream produced in the first
mixing drum.
[0076] Once the second mixing drum has produced a second dilbit
stream, a step 360 of feeding a second quantity of bituminous
material into the first mixing drum and a step 370 of spraying the
second stream of dilbit over the second quantity of bituminous
material inside of the first mixing drum can take place. In this
manner, the overall bitumen extraction method generates its own
solvent and becomes at least partially self-sufficient. The dilbit
moves in a counter-flow direction to the solids and becomes more
loaded with bitumen after each stage (i.e., mixing drum). Thus, the
dilbit leaving the first mixing drum and which has passed through
one or more downstream mixing drums reaches optimal bitumen content
for further processing or separation.
[0077] Step 360 of feeding a second quantity of bituminous material
into the first mixing drum can be similar or identical to step 300
and 100 described in greater detail above. Accordingly, in some
embodiments, the bituminous material is oil sands and is fed into
the first mixing drum using conveyor belts or the like.
[0078] Step 370 of spraying the second dilbit stream over the
second quantity of bituminous material can be similar or identical
to step 310 and 110 described in greater detail above. The dilbit
can be sprayed over the second quantity of bituminous material
using a spray bar extending into the first mixing drum, and the
first mixing drum may be rotating about its axis as dilbit is
sprayed over the bituminous material. Additionally, the result of
this step is similar to the spraying steps described above. A
slurry is formed that include bitumen dissolved in solvent and
solvent-wet tailings. The slurry can be separated as described
above, and a continuous process of bitumen extraction is thus
established.
[0079] In some embodiments, the second stream of dilbit is
subjected to a further separation step prior to being sprayed over
the second quantity of bituminous material inside of the first
mixing drum. The separation step generally aims to remove any solid
material from the dilbit, such as sand that may have filtered
through the screen liner inside of the second mixing drum. Any
suitable separation method can be used to separate solid material
from the second stream of dilbit. In some embodiments, the
separation is carried out by processing the dilbit in a
hydrocyclone, a centrifuge, filter, clarifier, desander, or through
a screen.
[0080] In some embodiments, the second stream of dilbit is heated
prior to being injected into the first mixing drum. For example,
the second dilbit stream can be heated to a temperature in the
range of from 20.degree. C. to 40.degree. C. prior to being sprayed
over bituminous material inside of the first mixing drum. Any
suitable type of heating mechanism can be used to heat the second
dilbit stream, including the use of a heat exchanger.
[0081] The composition of the second stream of dilbit may also be
adjusted prior to being sprayed over the second quantity of
bituminous material. Thus, in scenarios where the dilbit sprayed
over the bituminous material has a preferred bitumen content and
solvent content, additional solvent can be added to the dilbit
prior to spraying. Other processing steps to adjust the composition
of the dilbit can also be used, such as removing solvent or bitumen
from the dilbit.
[0082] The first dilbit stream and any other dilbit produced by the
first mixing drum (such as dilbit produced after spraying the
second stream of dilbit over the second quantity of bituminous
material and separating the resulting slurry) can be transported to
a dilbit storage unit. Dilbit in the dilbit storage unit can
subsequently be processed to separate the bitumen from the solvent.
Any suitable manner of carrying out such a separation can be used,
such as by evaporating off the solvent. Solvent separated from the
bitumen can be collected and reused in the process, while bitumen
can be upgraded into lighter hydrocarbon products. In some
embodiments, the dilbit leaving the first mixing drum can be
subjected to solids separation such as the solids separation
discussed in greater detail above prior to being stored in the
dilbit storage tank. In some embodiments, the separation process
uses a hydrocyclone, centrifuge, desander, switchable filter tube,
or screen and removes solid material such as sand that may be
contained in the dilbit upon removal from the first mixing
drum.
[0083] The first dilbit stream produced from step 320 can typically
include from about 30 to about 60 wt % bitumen and from about 40 to
about 70 wt % solvent. Relatively small amounts of solid material,
such as sand, may also be included in the first dilbit stream. In
some embodiments, the first dilbit stream may include from about 0
to about 3 wt % solid material. The first tailings stream produced
from step 320 can generally include from about 50 to about 75 wt %
inert materials (such as clay and sand), from about 0 to about 5 wt
% water, from about 25 to about 40 wt % solvent, and from about 3
to about 15 wt % bitumen. The second dilbit stream produced from
step 350 can typically include less bitumen content than the first
dilbit stream, such as from about 20 to about 50 wt %, and the
second tailings stream can typically include less bitumen content
then the first tailings stream, such as from about 1% to about 8%
wt %. When the slurry produced from step 370 is separated into a
dilbit stream and a tailings stream, the dilbit stream can
typically have a bitumen content in the range of from 5 to 30 wt %
and the tailings can have a bitumen content in the range of from 0
to 5 wt % (or greater if a solvent is used that precipitates
asphaltenes).
[0084] While FIG. 3 includes two mixing steps carried out in two
mixing drums, the method can include further mixing steps that
utilize still additional mixing drums. For example, the
bitumen-depleted tailings produced in the second mixing drum can be
transported to a third mixing drum, where solvent is sprayed over
the tailings, the resulting slurry is separated, and the separated
dilbit is used in the first and/or second mixing drum. Ultimately,
any suitable number of mixing steps and mixing drums, with the
mixing drums be generally aligned in the order described above
(i.e., mixing drum X+1 receives tailings from mixing drum X, and
mixing drum X+1 provides a dilbit that can be used in any of the
preceding mixing drums). With reference to FIG. 4, a process
diagram of embodiments of the above described method is
illustrated. A first mixing drum 400 is provided, which receives
bituminous material 410 such as oil sand. Solvent 420 (for example,
dilbit) is sprayed over the bituminous material 410 inside of the
first mixing drum 400 to create a slurry that can subsequently be
separated inside of the first mixing drum 400. The slurry is
separated into a first tailings stream 415 and a first dilbit
stream 416. The first tailings stream 415 is transported to a
second mixing drum 430. Dilbit 440 originating from downstream
processes is sprayed over the first tailings stream 415 inside of
the second mixing drum 430 to create a slurry, although in some
embodiments, fresh solvent can be used in place of dilbit 440. The
slurry is then separated into the a second tailings stream 435 and
a second dilbit stream 436. The second tailings stream 435 can
either be subjected to further bitumen extraction processing, such
as in a third mixing drum, or treated for solvent removal and
deposited as waste material. The second dilbit stream 436 is
transported first to a separation unit 470. The separation unit 470
removes solid material that may be present in the dilbit stream
436. The dilbit stream 436 (or a portion thereof) is then
transported back to the first mixing drum 400, where it can be
sprayed over additional bituminous material 410 being fed into the
first mixing drum 400.
[0085] The first dilbit stream 416 leaving the first mixing drum
400 can be transported to a separation unit 450 that is similar to
the separation unit 470. The separation unit 450 acts to remove
solid material from the first dilbit stream 416 prior to sending
the first dilbit stream 416 to a dilbit storage unit 460. From the
dilbit storage unit 460, the first dilbit stream 416 can be sent to
further processing units, such as unit for separating the bitumen
from the solvent.
[0086] In some embodiments, systems that can be used to carry out
the bitumen extraction methods described above include a first
mixing drum, a first separation unit, a second mixing drum, and
(optionally) a dilbit storage unit. The first mixing drum is
generally similar or identical to the mixing drums described in
greater detail above, and includes a first dilbit inlet, a first
dilbit outlet, and a first tailings outlet. The first separation
unit is also similar or identical to the separation units discussed
above, and is generally used to separate solid material from dilbit
that leaves the first mixing drum. The first separation unit
therefore includes a second dilbit inlet that is in fluid
communication with the first dilbit outlet of first mixing drum. In
this manner, dilbit leaving the first mixing drum can be
transported into the first separation unit. The first separation
unit also includes a cleaned dilbit outlet for transporting cleaned
dilbit (i.e., dilbit with less solid material than when the dilbit
entered the first separation unit) out of the first separation
unit, and a solid materials outlet for transporting separated solid
material out of the first separation unit.
[0087] The second mixing drum is generally similar or identical to
the mixing drums described in greater detail above, and includes a
first tailings inlet. The first tailings inlet is in fluid
communication with the first tailings outlet of the first mixing
drum, and allows for the first tailings stream leaving the first
mixing drum to be fed into the second mixing drum. Inside the
second mixing drum the first tailings unit will be subjected to
bitumen extraction by being sprayed with solvent that dissolves
bitumen that remains with the first tailings and subsequently
separating the dissolved bitumen from the tailings. Accordingly,
the second mixing drum also includes a second dilbit outlet and a
second tailings outlet for removing each component from the second
mixing drum.
[0088] The second dilbit outlet of the second mixing drum is in
fluid communication with the first dilbit inlet of the first mixing
drum so that dilbit leaving the second mixing drum can be sprayed
over bituminous material being fed into the first mixing drum. In
this manner, the solvent needed for bitumen extraction in the first
mixing drum is provided by the dilbit produced in the second mixing
drum, and the bitumen content of the dilbit moving in a
countercurrent direction through one or more mixing drums can be
increased to an optimal concentration for downstream processing or
separation.
[0089] The dilbit storage unit of the system includes a cleaned
dilbit inlet that is in fluid communication with the cleaned dilbit
outlet of the first separation unit. In this manner, the cleaned
dilbit exiting the first separation unit can be transported to and
stored in the dilbit storage unit. Dilbit in the dilbit storage
unit can subsequently be transported to downstream processing
units, such as a distillation unit for separating the solvent from
the bitumen.
[0090] The system described above can also include more than two
mixing drums. Any additional mixing drums are used in the same
manner as the first two mixing drums. For example, a third mixing
drum would receive the tailings from the second mixing drum and can
be used to provide a dilbit stream that is used in the first and/or
second mixing drum.
[0091] In some embodiments, the bitumen extraction method and the
mixing drum configurations described above are used in conjunction
with additional downstream processing. Typically, the downstream
processing includes conducting further bitumen extraction
processing on the bituminous material or the tailings exiting the
mixing drum. By conducting further processing on the bituminous
material or tailings, the overall extraction rate of bitumen from
the initial bituminous material can be improved.
[0092] In some embodiments, one or more hydrocyclones are used to
carry out further bitumen extraction on material exiting the mixing
drum. More specifically, the one or more hydrocyclones can be used
when separation of dilbit and tailings is not carried out inside of
the mixing drums and instead the mixing drum outputs a slurry of
solvent and bituminous material. Such a slurry is injected into a
hydrocyclone, which acts to separate the dilbit from the tailings.
The dilbit reports to the overflow stream of the hydrocyclone while
the tailings report to the underflow of the hydrocyclone. In this
manner, the mixing drum need not include separation apparatus (such
as an internal screen). The dilbit leaving the hydrocyclone can be
sent to a separation unit to separate the solvent from the bitumen,
or can be recycled for use as a solvent in bitumen extraction. The
tailings can be deposited back into the area from which the
bituminous material was mined.
[0093] FIG. 5 illustrates a general schematic of a mixing drum 510
having a single hydrocyclone 520 located downstream of the mixing
drum 510. In such a set up, the hydrocyclone 520 is used to
separate the slurry 515 that exits the mixing drum 510 into a
dilbit stream 525 and a tailings stream 526. As shown in FIG. 5,
the dilbit stream 525 leaving the hydrocylcone can be sent to a
separator 530 for separating the dilbit stream 525 into solvent and
bitumen. The separator 530 can either perform a total separation,
or as shown in FIG. 5, can remove a portion of bitumen while
recycling the dilbit back to the mixing drum 510. Once the dilbit
is recycled back to the mixing drum 510, it can be used in
subsequent mixing steps with bituminous material inside of the
mixing drum 510. The tailings stream 526 exits the bottom of the
hydrocyclone 520 and can be deposited as mine backfill.
[0094] Typical hydrocyclones suitable for use in the above
described method and system 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 slurry is introduced into the
hydrocyclone at a direction generally perpendicular to the axis of
the hydrocyclone. This induces a spiral rotation on the slurry
inside the hydrocyclone and enhances the radial acceleration on the
tailings within the slurry. 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).
[0095] When the density of the solid tailings phase is greater than
that of the fluid dilbit phase, 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.
[0096] The manner of transporting the slurry from the mixing drum
516 to the hydrocyclone 520 can include any suitable mechanism for
moving slurry away from the outlet of the mixing drum 510 and into
the hydrocyclone 520. In some embodiments, piping is used to
connect the outlet of the mixing drum 510 to the inlet of the
hydrocyclone 520. A pump 530 can also be used to ensure the
movement of the slurry from the mixing drum 510 to the hydrocyclone
520.
[0097] In some embodiments, including embodiments where separation
of the slurry does not occur inside of the mixing drum, the slurry
leaving the mixing drum is sent to a separation unit prior to being
sent to the hydrocyclone. Exemplary separation units suitable for
use in the method include, but are not limited to, thickeners,
clarifiers, or filters. Such separation units can be desirable when
clays are present in the slurry leaving the mixing drum. Separation
units such as thickeners can remove these clays and produce an
overflow of dilbit having reduced or eliminated clay content. The
underflow of the separation unit generally includes the
bitumen-depleted tailings having a solvent content, and this stream
can be sent to the hydrocyclone. In some embodiments, the
bitumen-depleted tails leaving a separation unit can be in the form
a filter cake, in which case additional solvent can be added to the
filter cake to re-slurry the material prior to sending the tailings
to the hydrocyclone.
[0098] In some embodiments, two or more hydrocyclones aligned in
series and located downstream of the mixing drum can be used to
improve the overall amount of bitumen recovered from the slurry.
The two or more hydrocyclones can use a counter current flow
wherein dilbit recovered from one hydrocyclone is recycled back and
added to the slurry being introduced to the previous hydrocyclone.
By so doing, the overall bitumen extraction efficiency can be
improved. Any number of hydrocyclones can be used in such a system,
and calculations or experimentation can be carried out to determine
the number of hydrocyclones necessary to maximize bitumen
extraction. In some embodiments, the number of hydrocyclones used
depends on how efficiently the hydrocyclones are at "washing" the
dilbit from the tailings, with additional hydrocyclones necessary
when the "washing" is less efficient.
[0099] FIG. 6 illustrates a system where four hydrocyclones 610,
620, 630, 640 are aligned in series downstream of the mixing drum
600. A pump 650, 651, 652, 653 is placed between the mixing drum
600 and the first hydrocyclone 610, between the first hydrocyclone
610 and the second hydrocyclone 620, between the second
hydrocyclone 620 and the third hydrocyclone 630, and between the
third hydrocyclone 630 and the fourth hydrocyclone 640 in order to
assist in the movement of material between each of the units. The
mixing drum 600 is provided for producing a slurry of bituminous
material and solvent, although in some embodiments the pump box of
pump 650 can serve as both the mixing drum 600 and the pump 650
when solvent and bituminous material arc fed directly into the pump
650. The hydrocyclones 610, 620, 630, 640 are provided for
separating the slurry into dilbit and tailings. In the series of
hydrocyclones, the tailings leaving each hydrocyclone are mixed
with additional solvent (e.g., dilbit) and sent into the next
hydrocyclone in the series until a tailings stream substantially
free of bitumen is produced. Simultaneously, the dilbit stream
leaving each hydrocyclone is sent to be mixed with the tailings
entering the previous hydrocyclone in the series until a dilbit
sufficiently loaded with bitumen is produced in the first
hydrocyclone in the series.
[0100] Referring still to FIG. 6, in operation the method begins
with introducing bituminous material 601 into the mixing drum 600
and spraying solvent 602 over the bituminous material 601 inside
the mixing drum 600 as described in greater detail above. The
mixing drum 600 does not include internal separation apparatus, and
therefore outputs a slurry 603 including bituminous material and
solvent. Enough solvent 602 is sprayed over the bituminous material
601 to ensure the slurry 603 is pumpable. While not shown in FIG.
6, the slurry can be pumped to a separation unit, such as the
thickener described previously, to remove, for example, clays from
the slurry and produce a tailings stream that is sent to the
hydrocyclones. Pump 650 pumps the slurry 603 to the first
hydrocyclone 610, where the slurry 603 is injected into the
hydrocyclone 610 at a direction generally perpendicular to the axis
of the hydrocyclone 610. Centrifugal forces act on the slurry 603
and separate the slurry into a first dilbit stream 611 and a first
tailings stream 612. The first dilbit stream 611 can include some
of the less dense solid particles of the slurry 603, and therefore
can be sent to a separation unit 660 that removes fine solids from
the first dilbit stream 611. In some embodiments, an objective of
the hydrocyclone system is to have the first hydrocyclone 610
produce a first dilbit stream 611 that includes a solids level of
less than 1000 wppm.
[0101] The first tailings stream 612 leaving the first hydrocyclone
610 is transported to the second hydrocyclone 620. Pump 651 helps
to move first tailings stream 612 towards the second hydrocyclone
620 and can also serve as a mechanism for adding further dilbit to
the first tailings stream 612 to ensure the first tailings stream
612 is pumpable. As discussed in greater detail below, the dilbit
added to the first tailings stream 612 can come from the third
hydrocyclone 630. The mixture of the first tailings stream 612 and
the dilbit is transported to and injected into the second
hydrocyclone 620 at a direction generally perpendicular to the axis
of the second hydrocyclone 620. As with the first hydrocyclone 610,
centrifugal forces act on the first tailings stream 612 to separate
the first tailings stream into a second dilbit stream 621 and a
second tailings stream 622. Because the slurry 603 leaving the
mixing drum 600 is in a pumpable condition by virtue of the amount
of solvent 602 added to the bituminous material 601 inside the
mixing drum 600, the second dilbit stream 621 need not be added
with the slurry 603. Instead, the second dilbit stream 621 can be
used as make-up solvent to be used inside the mixing drum 600 and
further load the second dilbit stream 621 with additional bitumen
content. Accordingly, the second dilbit stream 621 can be
transported to the mixing drum 600 and combined with solvent 602
entering the mixing drum 600. Alternatively, the second dilbit
stream 621 can replace the solvent 602, thereby making the overall
system generally self-sufficient (i.e., no fresh solvent is needed
for the mixing drum 603 stage after start up).
[0102] The second tailings stream 622 is transported to the third
hydrocylone 630 in much the same manner as the first tailings
stream 612 is transported to the second hydrocyclone 620, including
the use of a pump 652 to move the second tailings stream 622
towards the third hydrocyclone 630. The second tailings stream 622
can be mixed with dilbit obtained from the fourth hydrocyclone 640
in order to ensure that the second tailings stream 622 is pumpable.
Once transported into the third hydrocyclone 630, the second
tailings stream 622 is separated into a third dilbit stream 631 and
a third tailings stream 632. As mentioned above, the third dilbit
stream 631 is recycled back in the system to be added with the
first tailings stream 612 being sent into the second hydrocyclone
620.
[0103] The third tailings stream 632 leaving the third hydrocyclone
630 is transported towards the fourth hydrocyclone 640. During the
transport, the third tailings stream 632 can be mixed with
additional tailings solids that are obtained when the first dilbit
stream 611 is sent to the separation unit 660 to remove less dense
solid particles that report to the overflow in the first
hydrocyclone 610 rather than the underflow. The third tailings
stream 632 can also be mixed with solvent to ensure the third
tailings stream 632 is pumpable. The solvent will typically be a
fresh solvent rather than a dilbit stream obtained from another
hydrocyclone in the system. Once solvent and/or additional tailings
solids are added to the third tailings stream 632, the third
tailings stream 632 is injected into the fourth hydrocyclone 640
for separation into a fourth dilbit stream 641 and a fourth
tailings stream 642. The fourth dilbit stream 641 can be recycled
back to be mixed with the second tailings stream 622 being
transported to the third hydrocyclone 630.
[0104] After the fourth hydrocyclone 640, the fourth tailings
stream 642 can be in a condition where it is sufficiently stripped
of bitumen material and is therefore a final waste product of the
system and method. The fourth tailings stream 642 can include a
solvent content, and in some embodiments, the fourth tailings
stream 642 can be sent to a solvent recovery unit where the solvent
is removed from the tailings. Any solvent recovery unit or system
can be used to remove the solvent from the tailings, including a
belt dryer to flash recover the solvent. Solvent can also be
recovered using wash columns, wherein the tailings are packed in a
column and solvent is displaced out of the tailings by the
introduction into the column of various wash fluids.
[0105] As noted above, any number of hydrocyclones can be used to
carry out the bitumen extraction. Regardless of the number of
hydrocyclones used, general operating procedures can be followed.
For example, the last hydrocyclone in the series will produce a
tailings stream that has the lowest bitumen content of any of the
tailings streams produced by the various hydrocyclones in the
series and will not be sent to another hydrocyclone for the purpose
of separating dilbit from the tailings. However, the tailings
leaving the last hydrocylone in the series may include a solvent
content that can be recovered using various solvent recovery
processes. Additionally, the first hydrocyclone in the series will
produce a dilbit stream that has the highest bitumen content of the
any of the dilbit streams produced by the various hydrocyclones in
the series, and will therefore be the dilbit stream that is treated
as a product of the system rather than being recycled back into the
system. In some embodiments, the dilbit from the first hydrocyclone
in a series of hydrocyclones will be sent to a separation unit to
separate solvent from the bitumen, and the separated bitumen will
then be sent to further processing units where bitumen upgrading
takes place. The solvent removed from the bitumen can be recycled
back in the process. Furthermore, with the exception of the dilbit
stream produced by the first hydrocyclone, the dilbit leaving each
hydrocyclone in the series will be mixed with the tailings entering
the preceding hydrocyclone in the series. As described above, in
the case of the second hydrocyclone in the series, the dilbit can
be used as the solvent for the mixing drum step rather than being
added to the slurry produced by the mixing drum in order to make
the overall method more self sufficient.
[0106] As noted above, dilbit from each hydrocyclone is mixed with
tailings entering the previous hydrocyclone in order to ensure that
the tailings are pumpable. In some embodiments, the S:B ratio used
in the initial mixing drum is increased so that the dilbit obtained
from each hydrocyclone has a suitably high amount of solvent to
make the tailings pumpable when mixed with the dilbit. In
embodiments described above where one or more mixing drums are used
to extract bitumen, the S:B ratio can be within the range of 0.5:1
to 9:1. When one or more hydrocyclones are used downstream of the
mixing drum, the S:B ratio used in the mixing drum can range from
1.5:1 to 10:1, although any S:B ratio that produces a pumpable
slurry can be used. In addition to helping to ensure that addition
of the dilbit to the tailings makes the tailings pumpable, the
increased S:B ratio can also improve "wash" efficiency inside of
the hydrocyclones (i.e., result in improved separation of dilbit
and tailings). Each hydrocyclone in the circuit can be operated at
a different S:B ratio to help accomplish these goals.
[0107] In some embodiments, a second series of hydrocyclones can be
used to remove the solvent from the final tailings produced by the
first series of hydrocyclones. The second series of hydrocyclones
are arranged and operated in a similar or identical manner to the
first series of hydrocyclones. As shown in FIG. 7, the final
tailings 642 produced by the first series of hydrocyclones are
mixed with a solvent mixture 721 that can be the same solvent as
used previously to form a slurry. The mixture of solvent can be
obtained from the overflow of the second hydrocyclone 720 in the
second series of hydrocyclones. The slurry is then injected into a
first hydrocyclone 710, which uses centrifugal force to separate a
solvent mixture 711 from a first tailings 712. The first solvent
mixture 711 of the first hydrocyclone 710 can be sent to a
separation unit 740 where primary solvent is separated, while the
first tailings 712 are sent to the second hydrocyclone 720. Prior
to being injected into the second hydrocyclone 720, the first
tailings 712 are mixed with a third solvent mixture 731 obtained
from the overflow of the third (and in this case, final)
hydrocyclone 730. The second hydrocyclone 720 produces a second
solvent mixture 721 which, as noted previously, is mixed with the
final tailings 642 from the first series of hydrocyclones, and a
second tailings stream 722, which is mixed with fresh solvent and
injected into the third (and in this case, final) hydrocyclone 730.
The third tailings 732 produced by the third hydrocyclone 730 have
the smallest amount of solvent of any of the tailings produced in
the second series of hydrocyclones, and the third solvent mixture
731 is mixed with the second tailings 722.
[0108] Any of the hydrocyclones used in the methods and systems
described herein can include an external heating source for heating
the material inside of the hydrocyclone. The heating can be
indirect heating, such as through the use of steam.
[0109] In some embodiments, the downstream processing utilizes one
or more packed columns for conducting further bitumen extraction on
the bitumen-depleted tailings produced by the upstream mixing drum
(or mixing drums). in such embodiments, the downstream processing
generally includes introducing the bitumen-depleted tailings into
one or more packed columns, followed by passing solvent through the
tailings packed in the column(s). As the solvent passes through the
packed column(s), the solvent dissolves bitumen remaining in the
tailings and carries it through and out of the column as a bitumen
laden solvent. In some embodiments, the solvent used in the packed
column is the same solvent used in the upstream mixing drums, such
as a paraffinic solvent.
[0110] With reference to FIG. 8, the downstream processing method
can include a step 800 of loading bitumen-depleted tailings in a
column, a step 810 of feeding a first quantity of solvent into the
column, a step 820 of collecting bitumen-enriched solvent exiting
the column, and optionally, a step 830 of feeding the
bitumen-enriched solvent into the column.
[0111] With reference to the step 800 of loading bitumen-depleted
tailings in a column, the bitumen-depleted tailings generally
include the tailings produced by the upstream mixing drum or drums.
In embodiments where multiple mixing drums are used upstream of the
column, the tailings can come from the last mixing drum in the
series of mixing drums.
[0112] The column into which the tailings are loaded can be any
type of column suitable for carrying out bitumen. In some
embodiments, the column has a generally vertical orientation. The
vertical orientation may include aligning the column substantially
perpendicular to the ground, but also may include orientations
where the column forms angles less than 90.degree. with the ground.
In some embodiments, the column can 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.
[0113] The material of construction for the vertical column is also
not limited. Any material that will hold the bitumen material
within the column can be used. The material may also preferably be
a non-porous material such that various solvents fed into the
column may 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 fed into
the column as well as any potentially corrosive materials.
[0114] The shape of the column is not limited to a specific
configuration. Generally speaking, the column can have two ends
opposite one another, designated a top end and a bottom end. The
cross-section of the column can be any shape, such as a circle,
oval, square, rectangle, or the like. In some embodiments, the
cross-section of the column changes along the height of the column,
including both the shape and size of the column cross-section. The
column can be a straight line column having no bends or curves
along the height of the vertical column. Alternatively, the column
can include one or more bends or curves. In some embodiments, the
column is free of obstructions, such as platforms of stages.
[0115] A wide variety of dimensions can be used for the column,
including the height, inner cross sectional diameter and outer
cross sectional diameter of the column. In some embodiments, the
ratio of height to inner cross sectional diameter ranges from
0.25:1 to 15:1.
[0116] The tailings can be loaded in the column according to any
suitable method. For example, in some embodiments, the tailings are
generally loaded in the column by introducing the tailings into the
column at the top end of the column. The bottom end of the column
can be blocked, such as by a removable plug or by virtue of the
bottom end of the column resting against the floor. In some
embodiments, a metal filter screen at the bottom end of the column
can be used to maintain the bitumen material in the vertical
column. In such configurations, introducing the tailings at the top
end of the column fills the column with tailings.
[0117] In some embodiments, the tailings loaded into the column by
pouring the bitumen material into the top end of the column. In one
example, tailings can be transported to the column via a conveyor
having one end positioned over the top end of the column. In such a
configuration, the tailings fall into the column after it is
transported over the end of the conveyor positioned over the
column. Manual methods of loading tailings into the column can also
be used. such as mechanical or manual shoveling the tailings into
column. For larger diameter columns, automatic distribution systems
can be used, such as the systems disclosed in U.S. Pat. Nos.
4,555,210 and 6,729,365.
[0118] The amount of tailings loaded in the column may be such that
the tailings substantially fill the column. In some embodiments,
the tailings may be added to the column to occupy 90% or more of
the volume of the column. In some embodiments, the tailings may not
be filled to the top of the column so that room is provided to feed
solvent into the column.
[0119] Generally speaking, the loading of tailings into the column
as described above will lead to a well packed column. That is to
say, the tailings will settle into the vertical column in manner
that results in minimal void spaces within vertical column. If the
vertical column is not well packed (i.e., includes too many void
spaces or overly large void spaces), solvent added to the column to
dissolve and extract bitumen (a step of the method described in
greater detail below) will flow through the vertical column too
quickly. When solvent passes through the tailings too quickly, an
insufficient amount of solvation of bitumen occurs and a generally
poor extraction process results.
[0120] In some embodiments, additional steps may be taken to ensure
a packed column of tailings and thereby promote sufficient
solvation of bitumen when solvent is passed through the tailings
loaded in the column. In some embodiments, the size of individual
pieces of the tailings can be reduced prior to loading the tailings
into the column. Reducing the size of the pieces of the tailings
may help the pieces of the tailings settle closer to each other in
the column and avoid the formation of void spaces or overly large
void spaces. The pieces of tailings can be reduced in size by any
suitable procedure, such as by crushing or grinding the pieces. In
some embodiments, the pieces are reduced in size based on the
diameter of the column used. In some embodiments, the pieces are
reduced to a size that is 15% or less than the diameter of the
column. For example, when the column has a diameter of 40 inches,
the pieces can be reduced to a size of 6 inches or less. For
commercial operation the material is usually reduced to nominally 8
inches or less for ease of handling and to ensure dissolution
within adequate retention time.
[0121] In other embodiments, the tailings can be packed down once
it is loaded in the column in order to reduce or eliminate void
spaces. Any method of packing down the tailings may be used. In
some embodiments, a piston or the like is inserted into the top end
of the vertical column and force is applied to the piston to move
the piston downwardly into the column in order to pack down the
tailings. The piston may apply pressure downwardly on the tailings
loaded in the column as a consistent application of downward
pressure or as a series of downward blows. Alternatively, a
vibration device, such as the device disclosed in U.S. Pat. No.
3,061,278 can be used to pack down the tailings. Packing down of
the tailings can also be performed manually. Additionally, packing
may be allowed to occur under its own weight, including after
solvent has been added to the tailings. After solvent has been
added to the tailings and the bitumen has become partially
solvated, the mixture of solvent and tailings can compact and slump
down under its own weight. After the tailings are packed down once,
additional tailings can be added to the column to take up the space
in the column created by the packing. The packing down of tailings
and adding of further tailings can be repeated one or more
times.
[0122] In step 810, a first quantity of solvent is fed into the
column. One objective of adding solvent to the column is to
dissolve the bitumen content of the tailings loaded in the column.
Put another way, the solvent is added to the column to reduce the
viscosity of the bitumen and allow it to flow through and out of
the column. Without the solvent, the bitumen content of the
tailings at room temperature may have a viscosity in the range of
100,000 times that of water and will not flow through the column.
The addition of the solvent reduces the viscosity of the bitumen to
a flowable state and allows it to travel out of the column with the
first solvent.
[0123] Accordingly, the solvent used in step 810 can be any
suitable solvent for dissolving or reducing the viscosity of the
bitumen in the bitumen material. In some embodiments, the first
solvent includes a hydrocarbon solvent. The solvent can be the same
solvent as is used when mixing solvent and bituminous material in
the upstream mixing drum. In some embodiments, the solvent is a
paraffinic solvent, such as pentane.
[0124] The solvent added into the column need not be 100% solvent.
Other components can be included with the solvent when it is added
into the column. In some embodiments, the solvent added into the
column include a bitumen content. The solvent might include a
bitumen content when the solvent added into the column in step 810
is solvent that has already been used to extract bitumen. As
described in greater detail below, solvent that passes through
tailings in a column may exit the column as bitumen-enriched
solvent, and this bitumen-enriched solvent may be used to carry out
step 810 being performed on a different column packed with
tailings. For example, bitumen-enriched solvent collected from the
bottom of a first column as described in greater detail below may
be added to bitumen material loaded in a second column in order to
carry out step 810 in the second column.
[0125] The solvent can be fed into the column in a wide variety of
ways. For example, in some embodiments, solvent is injected into
the tailings loaded in the column at various locations along the
height of the column. Such injection may be accomplished through
the use of column side injectors that are spaced along the height
of the column and extend through the side wall of the column and
into the interior of the column where the tailings are loaded.
Injection of solvent at various locations along the height of the
column can also be accomplished by using a single pipe that extends
down into the column and includes various locations along the
length of the pipe where solvent can exit the pipe. The pipe can be
positioned down the center of the column or off to the side of the
column.
[0126] In configurations such as those described above, the solvent
may be injected into the column beginning with the lowest injection
positions first and moving upwardly through the column. Injecting
solvent into the column in this manner and in this order helps to
ensure percolation of solvent through the column and prevents the
column from plugging up as described in greater detail below.
[0127] In some embodiments, the amount of solvent added to the
column is based on a ratio of solvent to bitumen content in the
tailings on a v/v basis (herein referred to as "S:B") In some
embodiments, the S:B ratio is greater than 1.
[0128] As discussed above, the solvent can be injected into the
column starting from the bottom of the column and moving upwards to
the top of the column. Injecting the solvent into the column in
this manner may beneficially prevent the column from plugging by
ensuring that the S:B ratio does not fall below 1 at any location
inside the column. If solvent is added at the top of the column at
an S:B ratio of 1, a portion of the solvent may flow down the
column to a location where the S:B ratio is below 1 and therefore
does not sufficiently reduce the viscosity of the bitumen to flow
through the column. This may result in the column plugging up. By
introducing the solvent at an S:B ratio of at least 1 at the bottom
of the column and subsequently and sequentially adding solvent at
higher positions along the column at an S:B ratio greater than 1,
portions of the injected solvent may not be able to flow downwardly
to a location in the column where the S:B ratio is not greater than
1 and plug the column. Accordingly, the manner of injecting the
solvent into the column described in greater detail above may avoid
problems related to column plugging.
[0129] If the column does become plugged due to the S:B ratio
falling below 1 at a location within the column, steps can be taken
to unplug the column. More specifically, the location of the plug
can be identified and additional solvent can be injected into the
column at the injection point just below the plug (when the column
is operated in a downward flow mode). The additional solvent
injected into the column can be injected into the column in such a
manner as to close off the bottom of the column and force the
solvent to flow upwardly though the column. For example, increasing
the flow rate and pressure of the injected solvent may result in
closing off the bottom of the column. The upwardly moving solvent
may then displace and dissolve the bitumen phase causing the plug
due to the viscosity issues.
[0130] The solvent fed into the column flows downwardly through the
tailings loaded in the column. The solvent flows downwardly through
the height of the column via small void spaces in the tailings. The
solvent may travel the flow of least resistance through the
tailings. As the solvent flows through the tailings, the solvent
can dissolve bitumen contained in the tailings and thereby form
bitumen-enriched solvent. In some embodiments, 90%, preferably 95%,
and most preferably 99% or more of the bitumen in the tailings is
dissolved in the solvent and becomes part of the bitumen-enriched
solvent phase.
[0131] The bitumen-enriched solvent that flows downwardly through
the height of the column may exit the column at, for example, the
bottom end of the column. Accordingly, a step 820 of collecting the
bitumen-enriched solvent exiting the column is performed. Any
method of collecting the bitumen-enriched solvent can be used, such
as by providing a collection vessel at the bottom end of the
column. The bottom end of the column can include a metal filter
screen having a mesh size that does not permit bitumen material 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 until the bitumen-enriched solvent phase substantially or
completely stops exiting the column. In some embodiments,
collection is carried out for from 2 to 60 minutes.
[0132] In some embodiments, the bitumen-enriched solvent collected
in step 820 contains from about 10 wt % to about 60 wt % bitumen
and from about 40 wt % to about 90 wt % first solvent. Minor
amounts of non-bitumen material can also be included in the
bitumen-enriched solvent phase.
[0133] In some embodiments, the flow of solvent through the column
and the removal of bitumen-enriched solvent phase is aided by
adding a pressurized gas into the column either before or after
solvent is fed into the column. Applying a pressurized gas over the
tailings loaded in the column can facilitate the separation of the
bitumen-enriched solvent from the non-bitumen components of the
tailings loaded in the vertical column. Once liberated and having a
much reduced viscosity due to the addition of the solvent, the
bitumen-enriched solvent phase can be pushed out of the column
either by the continual addition of pressurized gas or by feeding
additional solvent into the column. The addition of additional
solvent or bitumen-enriched solvent collected in step 820 can
displace the liberated bitumen-enriched solvent from the tailings
by providing a driving force across a filtration element (i.e., the
non-bituminous components of the tailings). Any suitable gas may be
used. In some embodiments, the gas is nitrogen, carbon dioxide or
steam. The gas can also be added over the tailings loaded in the
vertical column in any suitable amount. In some embodiments, 1.8
m.sup.3 to 10.6 in.sup.3 of gas per ton of tailoings is used. This
is equivalent to a range of about 4.5 liters to 27 liters of gas
per liter of tailings. In certain embodiments, 3.5 m.sup.3 of gas
per ton of tailings is used.
[0134] After collecting bitumen-enriched solvent, a step 830 of
feeding the collected bitumen-enriched solvent back into the column
can optionally be performed. The bitumen-enriched solvent phase can
be fed into the column in a similar or identical manner as
described above with respect to feeding a first quantity of solvent
into the column. The bitumen-enriched solvent may be fed back into
the column "as is" or may be diluted with additional solvent prior
to feeding the bitumen-enriched solvent back into the column. The
amount of bitumen-enriched solvent phase fed into the column is not
limited. In some embodiments, the bitumen-enriched solvent fed into
the column is approximately 0.5 to 3.0 times the amount of bitumen
by volume contained in the original bitumen material.
[0135] In some embodiments, the bitumen-enriched solvent fed into
the column behaves much like the first quantity of solvent fed into
the column. The bitumen-enriched solvent flows downwardly through
the column, dissolving additional bitumen still contained in the
column and forcing any entrapped bitumen-enriched solvent out of
the column. The bitumen-enriched solvent eventually may exit the
column, where it may be collected in a similar or identical manner
to the collection step 820 described above.
[0136] The steps of collecting bitumen-enriched solvent and feeding
bitumen-enriched solvent back into the column can be repeated one
or more times in order to remove greater amounts of bitumen from
the tailings loaded in the column. In some examples, the steps of
collecting the bitumen-enriched solvent and feeding the
bitumen-enriched solvent into the column are repeated until less
than 1 wt % bitumen of the bitumen material is remaining in the
column.
[0137] In some embodiments, more than one column is provided for
carrying out the extraction of bitumen from tailings. The columns
can generally be aligned in parallel and can each receive a portion
of the tailings produced in the mixing drums upstream. The
bitumen-enriched solvent produced from each of the columns can be
combined for further use or processing. Similarly, the tailings
leaving each of the columns after bitumen extraction can be
combined for further processing or disposal.
[0138] In some embodiments, the bitumen-enriched solvent obtained
from processing the tailings in the columns can be used as the
solvent that is sprayed over bituminous material in the upstream
mixing drums. Alternatively, the bitumen-enriched solvent can be
separated into a solvent phase and a bitumen phase. The
bitumen-enriched solvent can also be divided such that some of the
bitumen-enriched solvent is used upstream in the mixing drums, and
a remaining portion is separated into solvent and bitumen.
[0139] In some embodiments, the tailings remaining in the column
after solvent has been passed therethrough contain a trace amount
solvent. Accordingly, further drying steps can be carried out in
order to remove and recover the trace amount of solvent. Any
suitable drying apparatus can be used. The drying apparatus
generally operates by heating the tailings to the point of
evaporating the solvent. The evaporated solvent can be collected,
condensed, and reused. The dried tailings can be disposed of.
[0140] With reference to FIG. 9, a system 900 including packed
columns downstream of the mixing drums is illustrated. The system
900 generally includes a mineral sizer 920, a first pulper 930, a
first thickener 940, a second pulper 950, a second thickener 960, a
wash column 970, and a dryer 980. While the system 900 includes,
for example, two pulpers, other embodiments of the system can have
fewer or more pulpers. The system 900 will generally include one
thickener paired with each pulper. The system 900 can also include
multiple wash columns. In some embodiments, the system 900 includes
four wash column aligned in parallel.
[0141] In operation, system 900 begins with bituminous material
910, such as the bituminous material described above, being
transported into the mineral sizer 920. Solvent 915, such as the
solvent described above, can be injected into the mineral sizer 920
at the same time as the bituminous material 910 (as shown in FIG.
9) and/or can be mixed with the bituminous material 910 prior to
its introduction into the mineral sizer 920. The mineral sizer 920
works to reduce the size of large clumps of material that may be
present in the bituminous material 910, and the solvent 915 helps
to begin the process of dissolving bitumen while reducing the wear
on the mineral sizer.
[0142] A slurry 925 of bituminous material and solvent exits the
mineral sizer 920 and is transported to the first pulper 930. In
the first pulper 930, solvent is sprayed over the slurry 925 as
described in greater detail above. The solvent sprayed over the
slurry 925 in the pulper 930 can be a fresh stream of solvent, or,
as shown in FIG. 9, can be recycle dilbit 961 obtained from the
downstream second thickener 960. In some embodiments, the solvent
used in the first pulper 930 is the same solvent used in the
mineral sizer 915 and as will be used in the second pulper 950.
When dilbit 961 is used, the solvent component of the dilbit can be
same solvent used throughout the rest of the system 900.
[0143] A first pulper slurry 935 is produced as a result of the
mixing of solvent and bituminous material in the first pulper 930.
In some embodiments, separation of the first pulper slurry 935 into
a dilbit stream and a bitumen-depleted slurry can be carried out
inside of the pulper. However, as shown in FIG. 9, the first pulper
slurry 935 leaves the first pulper 930 and is transported to a
first thickener 940. The first thickener 940 operates to separate
the first pulper slurry 935 into a dilbit stream 941 and a
bitumen-depleted slurry stream 942. The dilbit stream 941 can be
sent to further processing apparatus where the solvent component of
the dilbit stream 941 is separated from the bitumen component. The
bitumen-depleted slurry stream 942 is transported to a second
pulper 950.
[0144] The second pulper 950 operates in much the same way as the
first pulper 930. Solvent is sprayed over the bitumen-depleted
slurry stream 942 in order to dissolvent additional bitumen
content. The solvent can be clean solvent, or, ash shown in FIG. 9,
can be dilbit 972 obtained from the downstream wash column 970. In
some embodiments, the solvent used in the second pulper 950
(including the solvent component of the dilbit 972) is the same
solvent as used throughout the system 900.
[0145] A second pulper slurry 955 is produced as a result of the
mixing of solvent and bitumen-depleted slurry in the second pulper
950. In some embodiments, separation of the second pulper slurry
955 into a dilbit stream and a bitumen-depleted slurry can be
carried out inside of the pulper. However, as shown in FIG. 9, the
second pulper slurry 955 leaves the second pulper 950 and is
transported to a second thickener 960. The second thickener 960
operates to separate the second pulper slurry 955 into a dilbit
stream 961 and a bitumen-depleted slurry stream 962. The dilbit
stream 961 can be sent to further processing apparatus where the
solvent component of the dilbit stream 941 is separated from the
bitumen component, or can be recycled back for use in the first
pulper 930. The bitumen-depleted slurry stream 962 is transported
to one or more downstream wash columns 970.
[0146] The bitumen depleted slurry stream 962 is loaded in the one
or more wash columns 970, where solvent 971 is passed through the
bitumen-depleted slurry stream 962 in order to dissolve additional
bitumen and remove the bitumen from the bitumen-depleted slurry
stream 962 in the form of a dilbit stream 972. The solvent 971 used
in the wash column 972 can be the same solvent used through the
system 900. In some embodiments, multiple wash cycles are carried
out and can include recycling dilbit 972 back through the wash
column 970. Once a sufficient number of wash cycles have been
carried out, the dilbut 972 can be sent to separation apparatus for
separating solvent from bitumen, or, as shown in FIG. 9, can be
recycled back for use in the second pulper 950.
[0147] The solvent washing that takes place in the wash column 970
ultimately produces a solvent-wet tailings phase 973 that can be
removed from the wash column 970 and sent to a dryer for removal of
the trace amount of solvent included in the tailings phase 973. In
some embodiments, the dryer 980 can operate by heating the tailings
phase 973 to a temperature above the boiling point temperature of
the solvent component, thereby causing the solvent to evaporate and
exit the dryer 980 as a solvent vapor 981. The solvent vapor 981
can then be sent to a condenser for condensing the vapor back to a
liquid so that it might be reused in the system 900. Once the
solvent has been evaporated from the tailings, a dry tailings phase
982 can be discharged from the dryer and disposed of.
[0148] 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).
[0149] 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) arc 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.
[0150] 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.
* * * * *