U.S. patent application number 12/778655 was filed with the patent office on 2011-11-17 for apparatus and method for recovering a hydrocarbon diluent from tailings.
This patent application is currently assigned to TITANIUM CORPORATION, INC.. Invention is credited to Andy H. HILL, Kevin MORAN, Chakravarthy SISHTLA.
Application Number | 20110278202 12/778655 |
Document ID | / |
Family ID | 44910815 |
Filed Date | 2011-11-17 |
United States Patent
Application |
20110278202 |
Kind Code |
A1 |
MORAN; Kevin ; et
al. |
November 17, 2011 |
APPARATUS AND METHOD FOR RECOVERING A HYDROCARBON DILUENT FROM
TAILINGS
Abstract
An apparatus and a method for separating diluted tailings
containing a hydrocarbon diluent into a recovered diluent component
and a diluent recovered tailings component. The method includes
introducing the diluted tailings into a diluent recovery vessel so
that they form a tailings pool in the diluent recovery vessel,
introducing an amount of steam directly into the tailings pool,
mixing the diluted tailings which are contained in the tailings
pool, and maintaining the diluted tailings in the diluent recovery
vessel for a residence time. The apparatus includes a diluent
recovery vessel having a tailings pool section, a steam distributor
located in the tailings pool section, and a mixing device
associated with the tailings pool section.
Inventors: |
MORAN; Kevin; (Edmonton,
CA) ; HILL; Andy H.; (Glen Ellyn, IL) ;
SISHTLA; Chakravarthy; (Woodridge, IL) |
Assignee: |
TITANIUM CORPORATION, INC.
Edmonton
CA
|
Family ID: |
44910815 |
Appl. No.: |
12/778655 |
Filed: |
May 12, 2010 |
Current U.S.
Class: |
208/424 ;
196/14.52 |
Current CPC
Class: |
C10G 2300/807 20130101;
C10G 2300/802 20130101; B01D 17/0205 20130101; B01D 17/0214
20130101; C10G 1/047 20130101 |
Class at
Publication: |
208/424 ;
196/14.52 |
International
Class: |
C10G 1/04 20060101
C10G001/04; C10C 3/08 20060101 C10C003/08 |
Claims
1. A method of separating a diluted tailings comprising a
hydrocarbon diluent into a recovered diluent component and a
diluent recovered tailings component, wherein the diluted tailings
are derived from a bitumen froth treatment process, the method
comprising: (a) introducing the diluted tailings into an interior
of a diluent recovery vessel so that the diluted tailings form a
tailings pool in a tailings pool section of the diluent recovery
vessel; (b) introducing an amount of steam directly into the
tailings pool; (c) mixing the diluted tailings which are contained
in the tailings pool; (d) maintaining the diluted tailings in the
diluent recovery vessel for a residence time in order to separate
the diluted tailings into the recovered diluent component and the
diluent recovered tailings component; (e) recovering the recovered
diluent component from the diluent recovery vessel; and (f)
recovering the diluent recovered tailings component from the
diluent recovery vessel.
2. The method as claimed in claim 1 wherein the interior of the
diluent recovery vessel has an absolute pressure of between 20 kPa
and 120 kPa.
3. The method as claimed in claim 1 wherein the interior of the
diluent recovery vessel has a temperature of between 40 degrees
Celsius and 120 degrees Celsius.
4. The method as claimed in claim 1 wherein introducing the steam
directly into the tailings pool is comprised of distributing the
steam throughout the tailings pool with a steam distributor located
in the tailings pool.
5. The method as claimed in claim 4 wherein the steam distributor
is configured so that the steam is introduced directly into the
tailings pool in a direction toward a lower end of the diluent
recovery vessel.
6. The method as claimed in claim 1 wherein the residence time is
between 1 minute and 50 minutes.
7. The method as claimed in claim 1 wherein mixing the diluted
tailings is comprised of stirring the diluted tailings.
8. The method as claimed in claim 1 wherein mixing the diluted
tailings is comprised of passing the diluted tailings through a
recirculation circuit which is in communication with the tailings
pool.
9. The method as claimed in claim 8 wherein mixing the diluted
tailings is further comprised of stirring the diluted tailings.
10. The method as claimed in claim 7 wherein stirring the diluted
tailings is performed at a stirring intensity of between 0.05 watts
per kilogram and 40 watts per kilogram.
11. The method as claimed in claim 10 wherein stirring the diluted
tailings is performed at a stirring intensity of between 1.5 watts
per kilogram and 10 watts per kilogram.
12. The method as claimed in claim 8 wherein the diluted tailings
are introduced into the diluent recovery vessel at a feed rate by
weight, wherein the diluted tailings are passed through the
recirculation circuit at a recirculation rate by weight, and
wherein the recirculation rate is between 5 percent and 50 percent
of the feed rate.
13. The method as claimed in claim 12 wherein the recirculation
rate is between 10 percent and 20 percent of the feed rate.
14. The method as claimed in claim 1 wherein the diluted tailings
are introduced into the diluent recovery vessel at a feed rate by
weight, wherein the steam is introduced into the tailings pool at a
steam addition rate by weight, and wherein the steam addition rate
is between 5 percent and 30 percent of the feed rate.
15. The method as claimed in claim 14 wherein the steam addition
rate is between 5 percent and 15 percent of the feed rate.
16. The method as claimed in claim 1 wherein the diluent recovery
vessel has a lower end and an upper end and wherein the tailings
pool is formed at the lower end of the diluent recovery vessel,
further comprising providing a foam breaking device in the interior
of the diluent recovery vessel between the tailings pool and the
upper end of the diluent recovery vessel.
17. The method as claimed in claim 16 wherein the interior of the
diluent recovery vessel defines a vessel axis and wherein providing
the foam breaking device is comprised of rotating a foam breaker
about a foam breaker axis which is parallel with the vessel
axis.
18. The method as claimed in claim 17 wherein the foam breaker is
comprised of a brush.
19. The method as claimed in claim 17 wherein mixing the diluted
tailings is comprised of rotating a stirrer in the tailings pool
about a stirrer axis which is parallel with the vessel axis.
20. The method as claimed in claim 19 wherein the foam breaker and
the stirrer are both mounted on a stirring shaft and wherein the
stirring shaft has a stirring shaft axis which is coincident with
the foam breaker axis and the stirrer axis so that rotating the
foam breaker and rotating the stirrer are both comprised of
rotating the stirring shaft.
21. The method as claimed in claim 16, wherein the interior of the
diluent recovery vessel defines a vessel axis, wherein the tailings
pool section has a tailings pool cross-sectional area transverse to
the vessel axis in the interior of the diluent recovery vessel,
wherein providing the foam breaking device is comprised of
providing a foam breaking cross-sectional area transverse to the
vessel axis in the interior of the diluent recovery vessel, and
wherein the foam breaking cross-sectional area is larger than the
tailings pool cross sectional area.
22. The method as claimed in claim 21 wherein the interior of the
diluent recovery vessel is comprised of a vertical column.
23. The method as claimed in claim 1 wherein the hydrocarbon
diluent is comprised of a naphthenic type diluent.
24. The method as claimed in claim 23 wherein an interior of the
diluent recovery vessel has an absolute pressure of between 30 kPa
and 120 kPa.
25. The method as claimed in claim 23 wherein an interior of the
diluent recovery vessel has a temperature of between 60 degrees
Celsius and 120 degrees Celsius.
26. The method as claimed in claim 1 wherein the hydrocarbon
diluent is comprised of a paraffinic type diluent.
27. The method as claimed in claim 26 wherein an interior of the
diluent recovery vessel has an absolute pressure of between 20 kPa
and 110 kPa.
28. The method as claimed in claim 26 wherein an interior of the
diluent recovery vessel has a temperature of between 40 degrees
Celsius and 70 degrees Celsius.
29. The method as claimed in claim 1 wherein the diluted tailings
are comprised of a coarse mineral material fraction of a froth
treatment tailings.
30. The method as claimed in claim 29 wherein the hydrocarbon
diluent is comprised of a naphthenic type diluent.
31. The method as claimed in claim 29 wherein the hydrocarbon
diluent is comprised of a paraffinic type diluent.
32. The method as claimed in claim 29 wherein the residence time is
between 1 minute and 20 minutes.
33. The method as claimed in claim 32 wherein the diluted tailings
have a hydrocarbon diluent content and wherein the hydrocarbon
diluent content is less than 3 percent by weight of the diluted
tailings.
34. The method as claimed in claim 1 wherein the diluted tailings
are comprised of a fine mineral material fraction of a froth
treatment tailings.
35. The method as claimed in claim 34 wherein the hydrocarbon
diluent is comprised of a naphthenic type diluent.
36. The method as claimed in claim 34 wherein the hydrocarbon
diluent is comprised of a paraffinic type diluent.
37. The method as claimed in claim 34 wherein the residence time is
between 1 minute and 50 minutes.
38. The method as claimed in claim 37 wherein the diluted tailings
have a hydrocarbon diluent content and wherein the hydrocarbon
diluent content is greater than 3 percent by weight of the diluted
tailings.
39. An apparatus for separating a diluted tailings comprising a
hydrocarbon diluent into a recovered diluent component and a
diluent recovered tailings component, wherein the diluted tailings
are derived from a bitumen froth treatment process, the apparatus
comprising: (a) a diluent recovery vessel having a lower end, an
upper end, an interior, and a tailings pool section at the lower
end of the interior of the diluent recovery vessel; (b) a diluted
tailings inlet for introducing the diluted tailings into the
interior of the diluent recovery vessel; (c) a recovered diluent
component outlet at the upper end of the diluent recovery vessel
for recovering the recovered diluent component from the diluent
recovery vessel; (d) a diluent recovered tailings component outlet
at the lower end of the diluent recovery vessel for recovering the
diluent recovered tailings component from the diluent recovery
vessel; (e) a steam distributor located in the tailings pool
section of the diluent recovery vessel; and (f) a mixing device
associated with the tailings pool section of the diluent recovery
vessel, for mixing the diluted tailings which form a tailings pool
in the tailings pool section of the diluent recovery vessel.
40. The apparatus as claimed in claim 39 wherein the mixing device
is comprised of a stirrer which is located in the tailings pool
section of the diluent recovery vessel.
41. The apparatus as claimed in claim 39 wherein the mixing device
is comprised of a recirculation circuit which is in communication
with the tailings pool section of the diluent recovery vessel.
42. The apparatus as claimed in claim 41 wherein the recirculation
circuit is comprised of a pump for passing the diluted tailings
through the recirculation circuit.
43. The apparatus as claimed in claim 41 wherein the mixing device
is further comprised of a stirrer which is located in the tailings
pool section of the diluent recovery vessel.
44. The apparatus as claimed in claim 39, further comprising a foam
breaking device located in the interior of the diluent recovery
vessel between the tailings pool section of the diluent recovery
vessel and the upper end of the diluent recovery vessel.
45. The apparatus as claimed in claim 44 wherein the interior of
the diluent recovery vessel defines a vessel axis, wherein the foam
breaking device is comprised of a foam breaker, wherein the foam
breaker has a foam breaker axis, wherein the foam breaker is
rotatable about the foam breaker axis, and wherein the foam breaker
axis is parallel with the vessel axis.
46. The apparatus as claimed in claim 45 wherein the foam breaker
is comprised of a brush.
47. The apparatus as claimed in claim 45 wherein the mixing device
is comprised of a stirrer which is located in the tailings pool
section of the diluent recovery vessel.
48. The apparatus as claimed in claim 47 wherein the stirrer has a
stirrer axis, wherein the stirrer is rotatable about the stirrer
axis, and wherein the stirrer axis is parallel with the vessel
axis.
49. The apparatus as claimed in claim 48 wherein the foam breaker
and the stirrer are both mounted on a stirring shaft, wherein the
stirring shaft has a stirring shaft axis which is coincident with
the foam breaker axis and the stirrer axis, and wherein the
stirring shaft is rotatable in order to rotate the foam breaker and
the stirrer.
50. The apparatus as claimed in claim 44 wherein the interior of
the diluent recovery vessel defines a vessel axis, wherein the
tailings pool section has a tailings pool cross-sectional area
transverse to the vessel axis in the interior of the diluent
recovery vessel, wherein the foam breaking device is comprised of a
foam breaking cross-sectional area transverse to the vessel axis in
the interior of the diluent recovery vessel, and wherein the foam
breaking cross-sectional area is larger than the tailings pool
cross-sectional area.
51. The apparatus as claimed in claim 50 wherein the interior of
the diluent recovery vessel is comprised of a vertical column.
52. The apparatus as claimed in claim 39 wherein the steam
distributor is configured to introduce steam into the tailings pool
section of the diluent recovery vessel in a direction toward the
lower end of the diluent recovery vessel.
Description
TECHNICAL FIELD
[0001] An apparatus and method for separating diluted tailings
containing a hydrocarbon diluent into a recovered diluent component
and a diluent recovered tailings component.
BACKGROUND OF THE INVENTION
[0002] Oil sand is essentially comprised of a matrix of bitumen,
solid mineral material and water.
[0003] The bitumen component of oil sand includes hydrocarbons
which are typically quite viscous at normal in situ temperatures
and which act as a binder for the other components of the oil sand.
For example, bitumen has been defined by the United Nations
Institute for Training and Research as a hydrocarbon with a
viscosity greater than 10.sup.4 mPa s (at deposit temperature) and
a density greater than 1000 kg/m.sup.3 at 15.6 degrees Celsius.
[0004] The solid mineral material component of oil sand typically
consists of sand, rock, silt and clay. Solid mineral material may
be present in oil sand as coarse mineral material or fine mineral
material. The accepted division between coarse mineral material and
fine mineral material is typically a particle size of about 44
microns. Solid mineral material having a particle size greater than
about 44 microns is typically considered to be coarse mineral
material, while solid mineral material having a particle size less
than about 44 microns is typically considered to be fine mineral
material. Sand and rock are generally present in oil sand as coarse
mineral material, while silt and clay are generally present in oil
sand as fine mineral material.
[0005] A typical deposit of oil sand may contain (by weight) about
10 percent bitumen, up to about 6 percent water, with the remainder
being comprised of solid mineral material, which may include a
relatively small amount of impurities such as humic matter and
heavy minerals.
[0006] Water based technologies are typically used to extract
bitumen from oil sand ore originating from the Athabasca area in
northeastern Alberta, Canada. A variety of water based technologies
exist, including the Clark "hot water" process and a variety of
other processes which may use hot water, warm water or cold water
in association with a variety of different separation
apparatus.
[0007] In a typical water based oil sand extraction process, the
oil sand ore is first mixed with water to form an aqueous slurry.
The slurry is then processed to release bitumen from within the oil
sand matrix and prepare the bitumen for separation from the slurry,
thereby providing a conditioned slurry. The conditioned slurry is
then processed in one or more separation apparatus which promote
the formation of a primary bitumen froth while rejecting coarse
mineral material and much of the fine mineral material and water.
The separation apparatus may also produce a middlings stream from
which a secondary bitumen froth may be scavenged. This secondary
bitumen froth may be added to the primary bitumen froth or may be
kept separate from the primary bitumen froth.
[0008] A typical bitumen froth (comprising a primary bitumen froth
and/or a secondary bitumen froth) may contain (by weight) about 60
percent bitumen, about 30 percent water and about 10 percent solid
mineral material, wherein a large proportion of the solid mineral
material is fine mineral material. The bitumen which is present in
a typical bitumen froth is typically comprised of both
non-asphaltenic material and asphaltenes.
[0009] This bitumen froth is typically subjected to a froth
treatment process in order to reduce its solid mineral material and
water concentration by separating the bitumen froth into a bitumen
product and froth treatment tailings.
[0010] In a typical froth treatment process, the bitumen froth is
diluted with a froth treatment diluent to provide a density
gradient between the hydrocarbon phase and the water phase and to
lower the viscosity of the hydrocarbon phase. The diluted bitumen
froth is then subjected to separation in one or more separation
apparatus in order to produce the bitumen product and the froth
treatment tailings. Exemplary separation apparatus include gravity
settling vessels, inclined plate separators and centrifuges.
[0011] Some commercial froth treatment processes use naphthenic
type diluents (defined as froth treatment diluents which consist
essentially of or contain a significant amount of one or more
aromatic compounds). Examples of naphthenic type diluents include
toluene (a light aromatic compound) and naphtha, which may be
comprised of both aromatic and non-aromatic compounds.
[0012] Other commercial froth treatment processes use paraffinic
type diluents (defined as froth treatment diluents which consist
essentially of or contain significant amounts of one or more
relatively short-chained aliphatic compounds). Examples of
paraffinic type diluents are C4 to C8 aliphatic compounds and
natural gas condensate, which typically contains short-chained
aliphatic compounds and may also contain small amounts of aromatic
compounds.
[0013] Froth treatment processes which use naphthenic type diluents
(i.e., naphthenic froth treatment processes) typically result in a
relatively high bitumen recovery (perhaps about 98 percent), but
also typically result in a bitumen product which has a relatively
high solid mineral material and water concentration.
[0014] Froth treatment processes which use paraffinic type diluents
(i.e., paraffinic froth treatment processes) typically result in a
relatively lower bitumen recovery (in comparison with naphthenic
froth treatment processes), and in a bitumen product which has a
relatively lower solid mineral material and water concentration (in
comparison with naphthenic froth treatment processes). Both the
relatively lower bitumen recovery and the relatively lower solid
mineral material and water concentration may be attributable to the
phenomenon of asphaltene precipitation, which occurs in paraffinic
froth treatment processes when the concentration of the paraffinic
type diluent exceeds a critical level. This asphaltene
precipitation results in bitumen being lost to the froth treatment
tailings, but also provides a cleaning effect in which the
precipitating asphaltenes trap solid mineral material and water as
they precipitate, thereby separating the solid mineral material and
the water from the bitumen froth.
[0015] Froth treatment tailings therefore typically contain solid
mineral material, water, and an amount of residual bitumen (perhaps
about 2-12 percent of the bitumen which was contained in the
original bitumen froth, depending upon whether the froth treatment
process uses a naphthenic type diluent or a paraffinic type
diluent).
[0016] There are both environmental incentives and economic
incentives for recovering all or a portion of the residual bitumen
which is contained in froth treatment tailings.
[0017] In addition, the solid mineral material which is included in
froth treatment tailings typically comprises an amount of heavy
minerals. Heavy minerals are typically considered to be solid
mineral material which has a specific gravity greater than that of
quartz (i.e., a specific gravity greater than about 2.65). The
heavy minerals in the solid mineral material which is typically
contained in froth treatment tailings may include titanium metal
minerals such as rutile (TiO.sub.2), anatase (TiO.sub.2), ilmenite
(FeTiO.sub.3) and leucoxene (typically an alteration product of
ilmenite) and zirconium metal minerals such as zircon
(ZrSiO.sub.4). Titanium and zirconium bearing minerals are
typically used as feedstocks for manufacturing engineered materials
due to their inherent properties.
[0018] Although oil sand ore may contain a relatively low
concentration of heavy minerals, it is known that these heavy
minerals tend to concentrate in the bitumen froth which is
extracted from the oil sand ore, and therefore become concentrated
in the froth treatment tailings which result from froth treatment
processes, primarily as coarse mineral material. As a result, froth
treatment tailings may typically contain a sufficient concentration
of heavy minerals to provide an economic incentive to recover these
heavy minerals from the froth treatment tailings.
[0019] Froth treatment tailings are therefore tailings which are
derived from a bitumen froth treatment process. The prior art
further includes processes for treating bitumen froth to recover
heavy minerals therefrom and processes for treating froth treatment
tailings to recover bitumen and/or heavy minerals therefrom. These
processes are directed at the treatment of bitumen froth or
components of bitumen froth and may therefore be described
generally as bitumen froth treatment processes. In addition, these
processes typically result in the production of tailings which may
be described generally as tailings which are derived from a bitumen
froth treatment process.
[0020] Canadian Patent No. 861,580 (Bowman) describes a process for
the recovery of heavy metals from a primary bitumen froth. Canadian
Patent No. 879,996 (Bowman) describes a process for the recovery of
heavy metals from a secondary bitumen froth. Canadian Patent No.
927,983 (Penzes) describes a process for the recovery of heavy
metal materials from primary bitumen froth. Canadian Patent No.
1,013,696 (Baillie et al) describes a process for producing from
froth treatment tailings a quantity of heavy metal compounds such
as titanium and zirconium minerals which are substantially free of
bitumen and other hydrocarbon substances. Canadian Patent No.
1,076,504 (Kaminsky et al) describes a process for concentrating
and recovering titanium and zirconium containing minerals from
froth treatment tailings. Canadian Patent No. 1,088,883 (Trevoy et
al) describes a dry separatory process for concentrating
titanium-based and zirconium-based minerals from first stage
centrifuge froth treatment tailings. Canadian Patent No. 1,326,571
(Ityokumbul et al) describes a process for recovering metal values
such as titanium and zirconium from froth treatment tailings.
Canadian Patent No. 2,426,113 (Reeves et al) describes a process
for recovering heavy minerals from froth treatment tailings.
Canadian Patent Application No. 2,548,006 (Erasmus et al) describes
a process for recovering heavy minerals from froth treatment
tailings.
[0021] Canadian Patent No. 1,081,642 (Porteous et al) and Canadian
Patent No. 1,094,484 (Porteous et al) both describe processes for
recovering bitumen from froth treatment tailings. Canadian Patent
No. 1,238,597 (Seitzer) describes a process for the recovery of
diluent and bitumen from the predominantly aqueous phase of
electrostatically treated froth treatment tailings. Canadian Patent
No. 1,252,409 (St. Amour et al) describes a method for recovering
bitumen from a waste sludge obtained from a retention pond used to
store tailings from water extraction of bitumen from tar sands.
[0022] Canadian Patent Application No. 2,682,109 (Sury et al)
describes a method of extracting a hydrocarbon product from a
hydrocarbon-containing stream which comprises adding a first
solvent comprising an aromatic solvent to the stream to separate
the stream in to a hydrocarbon layer and an aqueous layer, and
adding a second solvent comprising a mixture of a polar solvent and
a non-polar solvent to the hydrocarbon layer to separate the
hydrocarbon product from the hydrocarbon layer.
[0023] Froth treatment tailings and other tailings which are
derived from a bitumen froth treatment process may also contain an
amount of a hydrocarbon diluent which has been used to facilitate
the bitumen froth treatment process or processes. For example, a
froth treatment diluent may be added to a bitumen froth to
facilitate the separation of the bitumen froth into the bitumen
product and the froth treatment tailings. Similarly, a hydrocarbon
diluent may be added to froth treatment tailings and/or components
of froth treatment tailings to facilitate the recovery of bitumen
and/or heavy minerals therefrom. It is desirable to recover at
least a portion of the hydrocarbon diluent from the tailings so
that it can be reused.
[0024] Hydrocarbon diluent is typically recovered from froth
treatment tailings in a naphtha recovery unit (NRU) in the case of
naphthenic type diluents, or in a tailings solvent recovery unit
(TSRU) in the case of paraffinic type diluents. Processes relating
to the recovery of naphthenic type diluents and paraffinic type
diluents from froth treatment tailings are known in the art.
[0025] Canadian Patent No. 1,027,501 (Simmer) describes a method
for recovering hydrocarbon diluent from hot centrifuge tailings
produced in the treatment of bitumen froth which comprises
introducing the tailings into a vacuum flash vessel maintained at a
sufficiently low sub-atmospheric pressure to vaporize the major
portion of the contained diluent.
[0026] Canadian Patent No. 2,272,035 (Sarkar et al) describes a
method for recovering hydrocarbon diluent from a slurry containing
heavy oil, particulate solids, diluent and water which comprises
introducing the slurry into a vacuum flash vessel chamber
maintained at a sufficiently low sub-atmospheric pressure to
vaporize diluent and water and introducing sufficient steam into a
pool of residual slurry at the bottom of the chamber to vaporize
residual diluent and water.
[0027] Canadian Patent No. 2,272,045 (King et al) describes a
method for recovering hydrocarbon diluent from tailings produced in
the treatment of bitumen froth which comprises introducing the
froth treatment tailings into a steam stripping vessel maintained
at near atmospheric pressure (the vessel having a plurality of
interior, vertically spaced shed decks), evenly distributing the
froth treatment tailings over the shed decks to maximize the
surface area of the froth treatment tailings, and introducing steam
below the shed decks so that it flows countercurrently to the froth
treatment tailings and heats the froth treatment tailings to
vaporize the hydrocarbon diluent and some water.
[0028] Canadian Patent No. 2,353,109 (Foulds et al) describes a
process for treating an underflow stream from a last separation
step in a paraffinic solvent process for separating bitumen from an
oil sands froth which comprises introducing the stream to a solvent
recovery vessel that is substantially free of internals and wherein
the temperature and pressure are such that the solvent is normally
a vapour, maintaining a pool of liquid and solids in the lower part
of the vessel at a controlled level for sufficient time to allow
the solvent to vapourize, and agitating the pool to a level of
agitation where the asphaltenes are dispersed, submerged and
re-agglomeration of asphaltenes is inhibited and the solids are
maintained in suspension.
[0029] Canadian Patent No. 2,587,166 (Sury), Canadian Patent No.
2,613,873 (Sury) and Canadian Patent No. 2,614,669 (Sury) each
describe processes for recovering paraffinic solvent from froth
treatment tailings which comprises introducing the froth treatment
tailings into a tailings solvent recovery unit (TSRU) and
introducing inert gas or steam into the TSRU in order to vaporize
at least a portion of the paraffinic solvent. In some embodiments,
the TSRU contains internals and the inert gas or steam is
introduced into the TSRU below the internals. In some embodiments,
the TSRU is substantially free of internals and the inert gas or
steam is introduced into a liquid pool which is formed in the
bottom of the TSRU. In some embodiments, tailings from the TSRU are
fed into a second TSRU which is maintained at an absolute pressure
which is lower than the first TSRU. In some embodiments, the
absolute pressure in the first TSRU is between 100 and 200 kPa and
the absolute pressure in the second TSRU is between 20 and 200 kPa.
In some embodiments, the froth treatment tailings contain
asphaltenes and the paraffinic solvent is vaporized from asphaltene
agglomerates.
[0030] Canadian Patent Application No. 2,651,155 (Sury et al)
describes a method of recovering hydrocarbons from bitumen froth
which comprises passing froth treatment tailings to a tailings
solvent recovery unit (TSRU) and optionally to a second TSRU, and a
third TSRU, wherein the operating pressure in each TSRU is lower
than the operating pressure in the preceding TSRU.
[0031] Canadian Patent Application No. 2,454,942 (Grant et al)
describes a process for separating a diluted tailings into a
recovered solvent component and a solvent recovered tailings
component which comprises discharging and returning a portion of
the solvent recovered tailings component to the solvent recovery
apparatus as a returned solvent recovered tailings component.
[0032] Canadian Patent Application No. 2,173,559 (Scheybeler) and
U.S. Pat. No. 6,712,215 (Scheybeler) each describe a method of
recovering solvent from oil sand tailings which comprises directing
a stream of tailings and saturated steam through a nozzle and
discharging the combined stream of tailings and saturated steam
against an impaction target.
SUMMARY OF THE INVENTION
[0033] References in this document to orientations, to operating
parameters, to ranges, to lower limits of ranges, and to upper
limits of ranges are not intended to provide strict boundaries for
the scope of the invention, but should be construed to mean
"approximately" or "about" or "substantially", within the scope of
the teachings of this document, unless expressly stated
otherwise.
[0034] In this document, "bitumen froth treatment process" includes
processes for treating a bitumen froth and processes for treating
one or more components of a bitumen froth.
[0035] In this document, "coarse mineral material fraction" means a
component of froth treatment tailings which comprises a minimal
amount of solid mineral material having a particle size less than
about 44 microns.
[0036] In this document, "diluted tailings" means tailings
containing an amount of a hydrocarbon diluent which result from a
bitumen froth treatment process for the treatment of a bitumen
froth and/or the treatment of one or more components of a bitumen
froth.
[0037] In this document, "fine mineral material fraction" means a
component of froth treatment tailings which comprises a minimal
amount of solid mineral material having a particle size greater
than or equal to about 44 microns.
[0038] In this document, "froth treatment tailings" means tailings
which are produced by a bitumen froth treatment process.
[0039] In this document, "heavy mineral concentrate" means a
component of froth treatment tailings into which heavy minerals
have been concentrated in a process for treating froth treatment
tailings.
[0040] In this document, "hydrocarbon diluent" means any substance
containing one or more hydrocarbon compounds and/or substituted
hydrocarbon compounds which is suitable for use for diluting and/or
dissolving bitumen in a bitumen froth treatment process.
[0041] In this document, "naphthenic type diluent" means a
hydrocarbon diluent which includes a sufficient amount of one or
more aromatic compounds so that the diluent essentially exhibits
the properties of a naphthenic type diluent as recognized in the
art, as distinguished from a paraffinic type diluent. In this
document, a naphthenic type diluent may therefore be comprised of a
mixture of aromatic and non-aromatic compounds, including but not
limited to such substances as naphtha and toluene.
[0042] In this document, "naphthenic froth treatment process" means
a bitumen froth treatment process which uses a sufficient amount of
one or more naphthenic type diluents so that the bitumen froth
treatment process is recognized in the art as a naphthenic froth
treatment process as distinguished from a paraffinic froth
treatment process.
[0043] In this document, "paraffinic type diluent" means a
hydrocarbon diluent which includes a sufficient amount of one or
more relatively short-chain aliphatic compounds (such as, for
example, C5 to C8 aliphatic compounds) so that the diluent
essentially exhibits the properties of a paraffinic type diluent as
recognized in the art, as distinguished from a naphthenic type
diluent. In this document, a paraffinic type diluent may therefore
be comprised of a mixture of aliphatic and non-aliphatic compounds,
including but not limited to such substances as natural gas
condensate.
[0044] In this document, "paraffinic froth treatment process" means
a bitumen froth treatment process which uses a sufficient amount of
one or more paraffinic type diluents so that the bitumen froth
treatment process is recognized in the art as a paraffinic froth
treatment process as distinguished from a naphthenic froth
treatment process.
[0045] The present invention is directed at an apparatus and a
method for separating diluted tailings containing a hydrocarbon
diluent into a recovered diluent component and a diluent recovered
tailings component.
[0046] The diluted tailings result from a bitumen froth treatment
process for the treatment of a bitumen froth and/or for the
treatment of one or more components of a bitumen froth.
Consequently, the diluted tailings are derived from a bitumen froth
treatment process. In some embodiments, the diluted tailings may be
comprised of, may consist of, or may consist essentially of froth
treatment tailings. In some embodiments, the diluted tailings may
be comprised of, may consist of, or may consist essentially of a
coarse mineral material fraction of froth treatment tailings. In
some embodiments, the diluted tailings may be comprised of, may
consist of, or may consist essentially of a fine mineral material
fraction of froth treatment tailings.
[0047] The diluted tailings may therefore be comprised of solid
mineral material and water, and may be comprised of an amount of
residual bitumen. The diluted tailings are further comprised of an
amount of a hydrocarbon diluent.
[0048] In some embodiments, the method of the invention may be
comprised of providing a tailings pool containing the diluted
tailings, introducing an amount of steam directly into the tailings
pool, mixing the diluted tailings which are contained in the
tailings pool, and providing a suitable residence time for the
diluted tailings so that an equilibrium state can be achieved or
approached amongst the liquid and vapour phases of the components
of the diluted tailings and the steam, thereby enabling the
recovery of recovered diluent component.
[0049] In some embodiments, the apparatus of the invention may be
comprised of a diluent recovery vessel having a tailings pool
section, a steam distributor located in the tailings pool section
of the diluent recovery vessel, and a mixing device associated with
the tailings pool section, for mixing diluted tailings which form a
tailings pool in the tailings pool section.
[0050] In an exemplary method aspect, the invention is a method of
separating a diluted tailings comprising a hydrocarbon diluent into
a recovered diluent component and a diluent recovered tailings
component, wherein the diluted tailings are derived from a bitumen
froth treatment process, the method comprising: [0051] (a)
introducing the diluted tailings into an interior of a diluent
recovery vessel so that the diluted tailings form a tailings pool
in a tailings pool section of the diluent recovery vessel; [0052]
(b) introducing an amount of steam directly into the tailings pool;
[0053] (c) mixing the diluted tailings which are contained in the
tailings pool; [0054] (d) maintaining the diluted tailings in the
diluent recovery vessel for a residence time in order to separate
the diluted tailings into the recovered diluent component and the
diluent recovered tailings component; [0055] (e) recovering the
recovered diluent component from the diluent recovery vessel; and
[0056] (f) recovering the diluent recovered tailings component from
the diluent recovery vessel.
[0057] In an exemplary apparatus aspect, the invention is an
apparatus for separating a diluted tailings comprising a
hydrocarbon diluent into a recovered diluent component and a
diluent recovered tailings component, wherein the diluted tailings
are derived from a bitumen froth treatment process, the apparatus
comprising: [0058] (a) a diluent recovery vessel having a lower
end, an upper end, an interior, and a tailings pool section at the
lower end of the interior of the diluent recovery vessel; [0059]
(b) a diluted tailings inlet for introducing the diluted tailings
into the interior of the diluent recovery vessel; [0060] (c) a
recovered diluent component outlet at the upper end of the diluent
recovery vessel for recovering the recovered diluent component from
the diluent recovery vessel; [0061] (d) a diluent recovered
tailings component outlet at the lower end of the diluent recovery
vessel for recovering the diluent recovered tailings component from
the diluent recovery vessel; [0062] (e) a steam distributor located
in the tailings pool section of the diluent recovery vessel; and
[0063] (f) a mixing device associated with the tailings pool
section of the diluent recovery vessel, for mixing the diluted
tailings which form a tailings pool in the tailings pool section of
the diluent recovery vessel.
[0064] In some embodiments, the method of the invention may be
performed using the exemplary apparatus of the invention as
described above. In some embodiments, the method of the invention
may be performed using an apparatus which is different from the
exemplary apparatus of the invention as described above.
[0065] The diluent recovery vessel may have any shape and/or size
which is suitable for separating the diluted tailings into the
recovered diluent component and the solvent recovered tailings
component. In some embodiments, the interior of the diluent
recovery vessel may be comprised of a horizontal column having a
ratio of vertical dimension to horizontal dimension which is less
than about 1:1. In some embodiments, the interior of the diluent
recovery vessel may be comprised of a vertical column having a
ratio of vertical dimension to horizontal dimension which is
greater than or equal to about 1:1.
[0066] The tailings pool section of the diluent recovery vessel may
be defined by any portion of the interior of the diluent recovery
vessel. In some embodiments, the tailings pool section may be
located at or adjacent to the lower end of the diluent recovery
vessel so that the diluted tailings form a tailings pool at or
adjacent to the lower end of the diluent recovery vessel.
[0067] In some embodiments, the diluent recovery vessel may be
comprised of internal structures for increasing the distribution
and surface area of the diluted tailings in the interior of the
diluent recovery vessel. In some embodiments, the internal
structures may be comprised of shed decks. In some embodiments, the
internal structures may be located between the diluted tailings
inlet and the tailings pool section of the diluent recovery
vessel.
[0068] In some embodiments, the diluent recovery vessel may be free
or substantially free of internal structures.
[0069] The method of the invention may be performed at any
operating pressure which is suitable for separating the diluted
tailings into the recovered diluent component and the diluent
recovered tailings component. In some embodiments, the method of
the invention may be performed at an operating pressure which is
sub-atmospheric or slightly above atmospheric pressure. In some
embodiments, the method of the invention may be performed at an
absolute pressure of between about 20 kPa (about 3 psia) and about
120 kPa (about 17 psia) as the operating pressure. In some
embodiments, the operating pressure of the method may be achieved
by maintaining the interior of the diluent recovery vessel at the
operating pressure.
[0070] The method of the invention may be performed at any
operating temperature which is suitable for separating the diluted
tailings into the recovered diluent component and the diluent
recovered tailings component. In some embodiments, the method of
the invention may be performed at an operating temperature which is
between about 40 degrees Celsius and about 120 degrees Celsius. In
some embodiments, the operating temperature of the method may be
achieved by maintaining the interior of the diluent recovery vessel
at the operating temperature.
[0071] The hydrocarbon diluent may be comprised of, may consist of,
or may consist essentially of any type of hydrocarbon diluent as
defined herein.
[0072] In some embodiments, the hydrocarbon diluent may be
comprised of, may consist of, or may consist essentially of a
naphthenic type diluent. In some embodiments, the hydrocarbon
diluent may be comprised of, may consist of, or may consist
essentially of a paraffinic type diluent. In some embodiments, the
hydrocarbon diluent may be comprised of a combination of one or
more naphthenic type diluents and/or one or more paraffinic type
diluents.
[0073] In some embodiments in which the hydrocarbon diluent is
comprised of, consists of, or consists essentially of a naphthenic
type diluent, the method of the invention may be performed at an
absolute pressure of between about 30 kPa (about 4 psia) and about
120 kPa (about 17 psia) as the operating pressure, and the method
may be performed at an operating temperature of between about 60
degrees Celsius and about 120 degrees Celsius.
[0074] In some embodiments in which the hydrocarbon diluent is
comprised of, consists of, or consists essentially of a paraffinic
type diluent, the method of the invention may be performed at an
absolute pressure of between about 20 kPa (about 3 psia) and about
110 kPa (about 16 psia) as the operating pressure, and the method
may be performed at an operating temperature of between about 40
degrees Celsius and about 70 degrees Celsius.
[0075] The method of the invention may be performed as a batch
method or as a continuous method. In some embodiments, the diluted
tailings may be introduced into the diluent recovery vessel at a
feed rate by weight of the diluted tailings. In some embodiments,
the feed rate of the diluted tailings may be dependent upon the
desired residence time of the diluted tailings in the diluent
recovery vessel.
[0076] The diluted tailings may be introduced into the interior of
the diluent recovery vessel at any location in the diluent recovery
vessel and in any manner. In some embodiments, the diluted tailings
may be introduced into the interior of the diluent recovery vessel
via a diluted tailings inlet. In some embodiments, the diluted
tailings may be introduced into the interior of the diluent
recovery vessel at a diluted tailings inlet which is located at or
adjacent to the upper end of the diluent recovery vessel.
[0077] In some embodiments, the diluted tailings may be introduced
into the interior of the diluent recovery vessel by distributing
the diluted tailings throughout the diluent recovery vessel. In
some embodiments, the diluted tailings may be introduced into the
interior of the diluent recovery vessel by distributing the diluted
tailings throughout the diluent recovery vessel at a location which
is located at or adjacent to the upper end of the diluent recovery
vessel. In some embodiments, the diluted tailings may be
distributed throughout the diluent recovery vessel by a tailings
distributor which is located in the interior of the diluent
recovery vessel and which is associated with the diluted tailings
inlet.
[0078] In some embodiments in which the diluent recovery vessel is
comprised of internal structures, the internal structures may be
located between the diluted tailings inlet and the tailings pool
section of the diluent recovery vessel.
[0079] The steam may be introduced into the tailings pool section
of the diluent recovery vessel and directly into the tailings pool
in any manner which is suitable for exposing the diluted tailings
to the steam. In some embodiments, introducing the steam directly
into the tailings pool may be comprised of distributing the steam
throughout the tailings pool with a steam distributor which is
located in the tailings pool. In some embodiments, the steam
distributor may be configured so that the steam is introduced
directly into the tailings pool in a direction toward the lower end
of the diluent recovery vessel.
[0080] The steam may be introduced into the diluent recovery vessel
at any steam addition rate by weight of the steam which is suitable
for separating the diluted tailings into the recovered diluent
component and the diluent recovered tailings component. In some
embodiments, the steam addition rate may be dependent upon the feed
rate of the diluted tailings into the diluent recovery vessel. In
some embodiments, the steam addition rate may be between about 5
percent and about 30 percent of the feed rate of the diluted
tailings. In some embodiments, the steam rate may be between about
5 percent and about 15 percent of the feed rate.
[0081] The recovered diluent component may be recovered from the
diluent recovery vessel at any location in the diluent recovery
vessel and in any manner. In some embodiments, the recovered
diluent component may be recovered from the diluent recovery vessel
via a recovered diluent component outlet. In some embodiments, the
recovered diluent component may be recovered from the diluent
recovery vessel via a recovered diluent component outlet which is
located at or adjacent to the upper end of the diluent recovery
vessel. In some embodiments, the recovered diluent component may be
recovered from the diluent recovery vessel by venting the recovered
diluent component from the diluent recovery vessel.
[0082] In some embodiments, the recovered diluent component which
is recovered from the diluent recovery vessel may be further
treated in order to condense the recovered diluent component and/or
in order to reduce the amount of water and other impurities which
may be contained in the recovered diluent component. In some
embodiments, the recovered diluent component or the further treated
recovered diluent component may be recycled for use in a bitumen
froth treatment process.
[0083] The diluent recovered tailings component may be recovered
from the diluent recovery vessel in any manner. In some
embodiments, the diluent recovered tailings component may be
recovered from the diluent recovery vessel via a diluent recovered
tailings component outlet which is located at or adjacent to the
lower end of the diluent recovery vessel and which is in
communication with the tailings pool section of the diluent
recovery vessel. In some embodiments, the diluent recovered
tailings component may be recovered from the diluent recovery
vessel at the diluent recovered tailings component outlet by
draining, pumping, augering or otherwise withdrawing the diluent
recovered tailings component from the diluent recovery vessel via
the diluent recovered tailings component outlet.
[0084] In some embodiments, the diluent recovered tailings
component may be further treated in order to reduce the amount of
water and other impurities which may be contained in the diluent
recovered tailings component and/or in order to recover additional
bitumen, heavy minerals, or other substances therefrom. In some
embodiments, the diluent recovered tailings component or the
further treated diluent recovered tailings component may be
disposed of in a similar manner as other tailings which result from
the processing of oil sand.
[0085] The residence time of the diluted tailings in the diluent
recovery vessel may be any residence time which is suitable for
achieving or approaching an equilibrium state amongst the liquid
and vapour phases of the components of the diluted tailings and the
steam.
[0086] In some embodiments, the residence time may be dependent
upon the composition of the diluted tailings. In some embodiments,
the residence time may increase as the amount of solid mineral
material having a particle size less than about 44 microns which is
present in the diluted tailings increases. It is theorized that
this phenomenon may be due to increased surface area and porosity
which may be associated with solid mineral material having a
particle size less than about 44 microns.
[0087] In some embodiments, the residence time may be dependent
upon the hydrocarbon diluent content of the diluted tailings (i.e.,
the concentration of hydrocarbon diluent in the diluted tailings).
In some embodiments, the residence time may increase as the
hydrocarbon diluent content of the diluted tailings increases. It
is theorized that this phenomenon may be due to mass transfer
considerations relating to the hydrocarbon diluent.
[0088] In some embodiments, the residence time may be dependent
upon both the composition of the diluted tailings and upon the
hydrocarbon diluent content of the diluted tailings. In some
embodiments, the hydrocarbon diluent content of the diluted
tailings may tend to increase as the amount of solid mineral
material having a particle size less than about 44 microns which is
present in the diluted tailings increases. It is theorized that
this phenomenon may be due to the increased surface area and
porosity which may be associated with solid mineral material having
a particle size less than about 44 microns, which may provide an
increased capability of the solid mineral material to absorb and/or
adsorb the hydrocarbon diluent.
[0089] In some embodiments, the residence time may be dependent
upon the steam addition rate, and/or upon the mixing intensity.
[0090] In some embodiments, the residence time may be dependent
upon a combination of factors including but not limited to the
composition of the diluted tailings, the hydrocarbon diluent
content of the diluted tailings, the steam addition rate, and/or
the mixing intensity.
[0091] In some embodiments, the residence time may be between about
1 minute and about 50 minutes.
[0092] In some embodiments in which the diluted tailings may be
comprised of, may consist of, or may consist essentially of a
coarse mineral material fraction of froth treatment tailings, the
residence time may be between about 1 minute and about 20 minutes.
In some embodiments in which the diluted tailings have a
hydrocarbon diluent content of less than about 3 percent by weight
of the diluted tailings, the residence time may be between about 1
minute and about 20 minutes.
[0093] In some embodiments in which the diluted tailings may be
comprised of, may consist of, or may consist essentially of a fine
mineral material fraction of froth treatment tailings, the
residence time may be between about 1 minute and about 50 minutes.
In some embodiments in which the diluted tailings have a
hydrocarbon diluent content which is greater than about 3 percent
by weight of the diluted tailings, the residence time may be
between about 1 minute and about 50 minutes.
[0094] The diluted tailings may be mixed in the tailings pool in
any manner using any structure, device or apparatus which is
suitable for mixing the diluted tailings. In some embodiments,
mixing the diluted tailings in the tailings pool may be performed
using a combination of methods and/or techniques and/or may be
performed using a combination of structures, devices or
apparatus.
[0095] In some embodiments, mixing the diluted tailings may be
comprised of stirring the diluted tailings. In some embodiments,
stirring the diluted tailings may be comprised of rotating a
stirrer in the tailings pool. The stirrer may be comprised of any
structure, device or apparatus which is capable of stirring the
diluted tailings.
[0096] Stirring the diluted tailings may be performed at any
stirring intensity which is suitable for mixing the diluted
tailings. In some embodiments, stirring the diluted tailings may be
performed at a stirring intensity of between about 0.05 watts per
kilogram of the diluted tailings and about 40 watts per kilogram of
the diluted tailings. In some embodiments, stirring the diluted
tailings may be performed at a stirring intensity of between about
1.5 watts per kilogram of the diluted tailings and about 10 watts
per kilogram of the diluted tailings.
[0097] In some embodiments, mixing the diluted tailings may be
comprised of passing the diluted tailings through a recirculation
circuit which is in communication with the tailings pool section of
the diluent recovery vessel and the tailings pool. In some
embodiments, the recirculation circuit may be comprised of a pump
for passing the diluted tailings through the recirculation circuit.
In some embodiments, the recirculation circuit may be associated
with the diluent recovered tailings component outlet.
[0098] The diluted tailings may be passed through the recirculation
circuit at any recirculation rate by weight which is suitable for
mixing the diluted tailings. In some embodiments, the recirculation
rate may be between about 5 percent and about 50 percent of the
feed rate. In some embodiments, the recirculation rate may be
between about 10 percent and about 20 percent of the feed rate.
[0099] In some embodiments, mixing the diluted tailings in the
tailings pool may be comprised of both stirring the diluted
tailings and passing the diluted tailings through a recirculation
circuit.
[0100] In some embodiments, mixing the diluted tailings in the
tailings pool may assist in distributing the steam throughout the
tailings pool by breaking the steam into smaller droplets and/or
dispersing the steam throughout the diluted tailings.
[0101] In some embodiments, the method of the invention may be
further comprised of providing a foam breaking device in the
interior of the diluent recovery vessel and the apparatus of the
invention may be further comprised of a foam breaking device
located in the interior of the diluent recovery vessel. In some
embodiments, the foam breaking device may be located between the
tailings pool and the upper end of the diluent recovery vessel. In
some embodiments, the foam breaking device may be located between
the tailings pool and the diluted tailings inlet. In some
embodiments, the foam breaking device may be located between the
tailings pool and the recovered diluent component outlet.
[0102] The foam breaking device may be comprised of any structure,
device or apparatus or combination of structures, devices or
apparatus which is capable of breaking, dissipating, reducing
and/or dispersing foam which may be formed from the diluted
tailings and the steam in the tailings pool. In some embodiments,
the foam breaking device may be comprised of a foam breaker.
[0103] In some embodiments, the foam breaker may be comprised of a
structure, device or apparatus which has a foam breaker axis and
which is rotatable about the foam breaker axis. In some
embodiments, the interior of the diluent recovery vessel may define
a vessel axis, and the foam breaker axis may be substantially
parallel with the vessel axis. In some embodiments, the foam
breaker axis may be coincident with the vessel axis. In some
embodiments, the foam breaker may be comprised of a brush which is
rotatable in the interior of the diluent recovery vessel about the
foam breaker axis.
[0104] In some embodiments, the foam breaker may assist in
dispersing the diluted tailings and/or breaking the diluted
tailings into smaller droplets as the diluted tailings pass through
the diluent recovery vessel from the diluted tailings inlet toward
the tailings pool. In some embodiments, the foam breaker may also
provide an increased surface area for the diluted tailings to
contact as the diluted tailings pass through the diluent recovery
vessel, which may enhance the heat and mass transfer
characteristics of the diluent recovery vessel.
[0105] In some embodiments in which the mixing device is comprised
of a stirrer, the stirrer may be rotatable in the tailings pool
section and the tailings pool about a stirrer axis which is
substantially parallel with the vessel axis. In some embodiments,
the stirrer axis may be coincident with the vessel axis. In some
embodiments, the stirrer axis may be coincident with the foam
breaker axis.
[0106] In some such embodiments, the foam breaker and the stirrer
may both be mounted on a stirring shaft, the stirring shaft may
have a stirring shaft axis which is coincident with the foam
breaker axis and the stirrer axis, and the stirring shaft may be
rotatable in order to rotate both the foam breaker and the stirrer.
In some such embodiments, the stirring shaft may be driven by a
stirring motor.
[0107] In some such embodiments, the foam breaker and the stirrer
may be independently rotatable by being mounted on different shafts
and/or by being driven by different motors.
[0108] In some embodiments, the foam breaking device may be
comprised of an increased horizontal dimension in the interior of
the diluent recovery vessel and/or an increased cross-sectional
area in the interior of the diluent recovery vessel, relative to
one or more other sections of the diluent recovery vessel.
[0109] In some such embodiments, the tailings pool section and thus
the tailings pool may have a tailings pool horizontal dimension and
the foam breaking device may be comprised of a foam breaking
horizontal dimension, wherein the foam breaking horizontal
dimension is larger than the tailings pool horizontal
dimension.
[0110] In some such embodiments, the tailings pool section and thus
the tailings pool may have a tailings pool cross-sectional area
transverse to the vessel axis in the interior of the diluent
recovery vessel and the foam breaking device may be comprised of a
foam breaking cross-sectional area transverse to the vessel axis in
the interior of the diluent recovery vessel, wherein the foam
breaking cross-sectional area is larger than the tailings pool
cross-sectional area.
[0111] In some such embodiments, the ratio of the foam breaking
horizontal dimension to the tailings pool horizontal dimension may
be between about 1.2:1 and about 2.5:1. In some such embodiments,
the ratio of the foam breaking cross-sectional area to the tailings
pool cross-sectional area may be between about 1.4:1 and about
6.25:1.
[0112] In some such embodiments, the foam breaking horizontal
dimension and/or the foam breaking cross-sectional area may extend
over an isolated section of the interior of the diluent recovery
vessel. In some such embodiments, the foam breaking horizontal
dimension and/or the foam breaking cross-sectional area may extend
over the entire vertical dimension of the interior of the diluent
recovery vessel with the exception of the tailings pool
section.
BRIEF DESCRIPTION OF DRAWINGS
[0113] Embodiments of the invention will now be described with
reference to the accompanying drawings, in which:
[0114] FIG. 1 is a schematic drawing of a first exemplary
embodiment of an apparatus according to the invention.
[0115] FIG. 2 is a schematic drawing of a second exemplary
embodiment of an apparatus according to the invention.
[0116] FIG. 3 is a table presenting data from bench scale
experimental testing of an embodiment of the method of the
invention, in which the diluted tailings consist of either a heavy
mineral concentrate obtained from froth treatment tailings, a
washed heavy mineral concentrate, a fine mineral material fraction
obtained from froth treatment tailings, or a dewatered fine mineral
material fraction.
[0117] FIG. 4 is a graph presenting data resulting from bench scale
experimental testing of an embodiment of the method of the
invention, in which the diluted tailings consist of a heavy mineral
concentrate obtained from froth treatment tailings.
[0118] FIG. 5 is a graph presenting data resulting from bench scale
experimental testing of an embodiment of the method of the
invention, in which the diluted tailings consist of a fine mineral
material fraction obtained from froth treatment tailings.
DETAILED DESCRIPTION
[0119] The present invention is directed at an apparatus and a
method for separating a diluted tailings into a recovered diluent
component and a diluent recovered tailings component.
[0120] FIG. 1 provides a schematic drawing of a first exemplary
embodiment of an apparatus according to the invention. FIG. 2
provides a schematic drawing of a second exemplary embodiment of an
apparatus according to the invention. The apparatus depicted in
FIG. 1 and FIG. 2 are examples of apparatus which may be used to
perform the method of the invention.
[0121] Referring to FIG. 1 and FIG. 2, there is depicted an
apparatus (20) for separating a diluted tailings into a recovered
diluent component and a diluent recovered tailings component.
[0122] The apparatus (20) is comprised of a diluent recovery vessel
(22). As depicted in FIG. 1 and FIG. 2, the diluent recovery vessel
(22) has a lower end (24), an upper end (26), an interior (28) and
a tailings pool section (30) at the lower end (24) of the interior
(28) of the diluent recovery vessel (22). The interior (28) of the
diluent recovery vessel (22) defines a vessel axis (32).
[0123] As depicted in FIG. 1 and FIG. 2, the interior (28) of the
diluent recovery vessel (22) is comprised of a vertical column so
that the vertical dimension of the interior (28) of the diluent
recovery vessel (22) is greater than or equal to the horizontal
dimension of the interior (28) of the diluent recovery vessel (22).
As depicted in FIG. 1 and FIG. 2, the ratio of the vertical
dimension of the interior (28) of the diluent recovery vessel (22)
to the horizontal dimension of the interior (28) of the diluent
recovery vessel (22) is between about 5:1 and about 6:1.
[0124] The apparatus is further comprised of a diluted tailings
inlet (38) for introducing diluted tailings (40) into the interior
(28) of the diluent recovery vessel (22). As depicted in FIG. 1 and
FIG. 2, the diluted tailings inlet (38) is located adjacent to the
upper end (26) of the diluent recovery vessel (22). The diluted
tailings inlet (38) is in communication with a source (not shown)
of the diluted tailings (40).
[0125] The diluted tailings (40) are tailings which are derived
from a bitumen froth treatment process, and may be comprised of,
may consist of, or may consist essentially of froth treatment
tailings, a fine mineral material fraction of froth treatment
tailings, a coarse mineral material fraction of froth treatment
tailings, a heavy mineral concentrate produced from froth treatment
tailings, and/or any other tailings which are derived from froth
treatment tailings.
[0126] The diluted tailings (40) are therefore typically comprised
of solid mineral material, water, and an amount of residual
bitumen. The diluted tailings (40) are further comprised of an
amount of a hydrocarbon diluent such as, for example, a naphthenic
type diluent and/or a paraffinic type diluent.
[0127] A diluted tailings heater (42) is interposed between the
source of the diluted tailings (40) and the diluted tailings inlet
(38). The diluted tailings heater (42) transfers heat to the
diluted tailings (40) in order to raise the temperature of the
diluted tailings (40) to a desired feed temperature. The desired
feed temperature of the diluted tailings (40) depends upon the
composition of the diluted tailings (40), including the composition
of the hydrocarbon diluent which is included in the diluted
tailings (40).
[0128] The diluted tailings inlet (38) is connected or otherwise
associated with a tailings distributor (44) which is located in the
interior (28) of the diluent recovery vessel (22). The tailings
distributor (44) distributes the diluted tailings (40) throughout
the interior (28) of the diluent recovery vessel (22).
[0129] The diluted tailings (40) move downward through the interior
(28) of the diluent recovery vessel (22) from the tailings
distributor (44) and form a tailings pool (46) in the tailings pool
section (30) of the diluent recovery vessel (22).
[0130] As depicted in FIG. 1 and FIG. 2, the diluent recovery
vessel (22) is substantially free of internal structures (not
shown) such as shed decks or other structures for increasing the
distribution and the surface area of the diluted tailings in the
interior (28) of the diluent recovery vessel (22). It is believed
that internal structures will not normally be required in the
diluent recovery vessel (22) in the practice of the invention. If,
however, internal structures are provided in the apparatus (20),
they may typically be provided between the diluted tailings inlet
(38) and the tailings pool section (30) of the diluent recovery
vessel (22).
[0131] The apparatus (20) is further comprised of a recovered
diluent component outlet (48) for recovering a recovered diluent
component (50) from the diluent recovery vessel (22). As depicted
in FIG. 1 and FIG. 2, the recovered diluent component outlet (48)
is located at the upper end (26) of the diluent recovery vessel
(22). The recovered diluent component outlet (48) is in
communication with a condensing apparatus (52).
[0132] As depicted in FIG. 1 and FIG. 2, the condensing apparatus
(52) is comprised of a condenser (54) and a liquid separator vessel
(56). Heat is removed from the recovered diluent component (50) in
the condenser (54) in order to produce a condensed recovered
diluent component (58). The condensed recovered diluent component
(58) is separated in the liquid separator vessel (56) into
recovered hydrocarbon diluent (60) and recovered water (62).
[0133] The apparatus (20) is further comprised of a diluent
recovered tailings component outlet (68) for recovering a diluent
recovered tailings component (70) from the diluent recovery vessel
(22). As depicted in FIG. 1 and FIG. 2, the diluent recovered
tailings component outlet (68) is located at the lower end (24) of
the diluent recovery vessel (22) at the bottom of the tailings pool
section (30) of the diluent recovery vessel (22). The diluent
recovered tailings component (70) may be recovered from the diluent
recovery vessel (22) via the diluent recovered tailings component
outlet (68) by draining, pumping, augering or otherwise withdrawing
the diluent recovered tailings component (70).
[0134] The apparatus (20) is further comprised of a steam
distributor (78) located in the tailings pool section (30) of the
diluent recovery vessel (22) for introducing an amount of steam
(80) directly into the tailings pool section (30) of the diluent
recovery vessel (22). The steam distributor (78) distributes the
steam (80) throughout the tailings pool section (30) of the diluent
recovery vessel (22).
[0135] As depicted in FIG. 1 and FIG. 2, the steam distributor (78)
may be comprised of a sparger ring, a fritted material or other
suitable structure, device or apparatus which provides an array of
apertures (not shown) for distributing the steam (80) throughout
the tailings pool section (30). In order to minimize the likelihood
of plugging of the apertures due to the movement of the diluted
tailings (40) downward in the tailings pool section (30), the steam
distributor (78) may be configured to introduce the steam (80) into
the tailings pool section (30) of the diluent recovery vessel (22)
in a direction toward the lower end (24) of the diluent recovery
vessel (22) by locating the apertures on a lower side of the steam
distributor (78).
[0136] The steam distributor (78) is in communication with a source
(not shown) of the steam (80). The source of the steam (80) may be
comprised of a heater (not shown) or a boiler (not shown) for
heating water to produce the steam (80).
[0137] The apparatus (20) is further comprised of a mixing device
(88) associated with the tailings pool section (30) of the diluent
recovery vessel (22), for mixing the diluted tailings (40) which
form the tailings pool (46) in the tailings pool section (30) of
the diluent recovery vessel (22).
[0138] As depicted in FIG. 1 and FIG. 2, the mixing device (88) is
comprised of a stirrer (90) which is located in the tailings pool
section (30) of the diluent recovery vessel (22). The stirrer (90)
is mounted on a stirring shaft (92) which provides a stirrer axis
(94) for the stirrer (90). As depicted in FIG. 1 and FIG. 2, the
stirrer axis (94) is substantially parallel with the vessel axis
(32) and is also substantially coincident with the vessel axis
(32). The stirring shaft (92) is rotatable so that the stirrer (90)
is rotatable about the stirrer axis (94). The stirring shaft (92)
is driven by a stirring motor (96).
[0139] As depicted in FIG. 1 and FIG. 2, the mixing device (88) is
further comprised of a recirculation circuit (100) which is in
communication with the tailings pool section (30) of the diluent
recovery vessel (22). The diluted tailings (40) are passed through
the recirculation circuit (100) in order to mix the diluted
tailings (40). The recirculation circuit (100) is comprised of a
conduit loop (102) and a pump (104) for passing the diluted
tailings (40) through the recirculation circuit (100).
[0140] As depicted in FIG. 1 and FIG. 2, the recirculation circuit
(100) is associated with the diluent recovered tailings component
outlet (68) so that a portion of the diluent recovered tailings
component (70) which is recovered from the diluent recovery vessel
(22) via the diluent recovered tailings component outlet (68) is
recirculated back to the tailings pool section (30).
[0141] The apparatus (20) is further comprised of a foam breaking
device (110) in the interior (28) of the diluent recovery vessel
(22). FIG. 1 and FIG. 2 depict alternate embodiments of the foam
breaking device (110).
[0142] Referring to FIG. 1, a first embodiment of the foam breaking
device (110) is comprised of a foam breaker (112) which is located
between the tailings pool section (30) of the diluent recovery
vessel (22) and the upper end (26) of the diluent recovery vessel
(22). The foam breaker (112) is rotatable about a foam breaker axis
(114). As depicted in FIG. 1, the foam breaker axis (114) is
substantially parallel with the vessel axis (32) and is also
substantially coincident with the vessel axis (32). As depicted in
FIG. 1, the foam breaker (112) is mounted on the stirring shaft
(92) so that rotation of the stirring shaft (92) by the stirring
motor (96) rotates both the stirrer (90) and the foam breaker
(112). As depicted in FIG. 1, the foam breaker (112) is comprised
of a brush.
[0143] The foam breaker (112) may assist in reducing the amount of
foam which accumulates in the diluent recovery vessel (22). The
foam breaker (112) may also assist in dispersing the diluted
tailings (40) and/or breaking the diluted tailings (40) into
smaller droplets as the diluted tailings (40) pass through the
diluent recovery vessel (22) from the diluted tailings inlet (38)
toward the tailings pool section (30). The foam breaker (112) may
also provide an increased surface area for the diluted tailings
(40) to contact as the diluted tailings (40) pass through the
diluent recovery vessel (22), which may enhance the heat and mass
transfer characteristics of the diluent recovery vessel (22).
[0144] Referring to FIG. 2, a second embodiment of the foam
breaking device (110) is comprised of an increased horizontal
dimension in the interior (28) of the diluent recovery vessel (22)
and/or an increased cross-sectional area in the interior (28) of
the diluent recovery vessel (22), relative to the tailings pool
section (30) of the interior (28) of the diluent recovery vessel
(22).
[0145] More particularly, the tailings pool section (30) is
comprised of a tailings pool horizontal dimension (120), the foam
breaking device (110) is comprised of a foam breaking horizontal
dimension (122), and the foam breaking horizontal dimension (122)
is larger than the tailings pool horizontal dimension (120).
Similarly, the tailings pool section (30) is comprised of a
tailings pool cross-sectional area (124), the foam breaking device
(110) is comprised of a foam breaking cross-sectional area (126),
and the foam breaking cross-sectional area (124) is larger than the
tailings pool cross-sectional area (126).
[0146] As depicted in FIG. 2, the ratio of the foam breaking
horizontal dimension (122) to the tailings pool horizontal
dimension (120) is about 1.75:1. As depicted in FIG. 2, the ratio
of the foam breaking cross-sectional area (126) to the tailings
pool cross-sectional area (124) is about 3:1.
[0147] As depicted in FIG. 2, the increased foam breaking
horizontal dimension (122) and the increased foam breaking
cross-sectional area (126) extends over an isolated section of the
interior (28) of the diluent recovery vessel (22).
[0148] The method of the invention may be performed using the
apparatus of the invention, or the method of the invention may be
performed using an alternate apparatus or combination of
apparatus.
[0149] The performance of the method of the invention using an
apparatus similar to the apparatus (20) depicted in FIG. 1 and/or
FIG. 2 is now described.
[0150] The method of the invention may be performed as a batch
method or as a continuous method. In the description which follows,
the method of the invention is described using the apparatus (20)
depicted in FIG. 1 and/or FIG. 2 in a continuous method.
[0151] Diluted tailings (40) from a source of diluted tailings (40)
are delivered to the diluted tailings heater (42) where they are
heated to a desired feed temperature. The desired feed temperature
may be the same as or different from the desired operating
temperature for the method of the invention, depending upon whether
a heater is provided in the diluent recovery vessel (22) and
depending upon the desired operating temperature. In some
embodiments, a desired operating temperature range for the method
may generally be between about 40 degrees Celsius and about 120
degrees Celsius.
[0152] If the hydrocarbon diluent which is contained in the diluted
tailings (40) consists of one or more naphthenic type diluents, the
desired operating temperature for the method may generally be
higher than if the hydrocarbon diluent consists of one or more
paraffinic type diluents. In some embodiments, a desired operating
temperature range for the method in conjunction with naphthenic
type diluents may be between about 60 degrees Celsius and about 120
degrees Celsius. In some embodiments, a desired operating
temperature range for the method in conjunction with paraffinic
type diluents may be between about 40 degrees Celsius and about 70
degrees Celsius. In some embodiments, a desired operating
temperature range for the method in conjunction with a mixture of
naphthenic type diluents and paraffinic type diluents may be a
compromise of the two above ranges.
[0153] The diluted tailings (40) pass from the diluted tailings
heater (42) to the diluted tailings inlet (38) and then to the
tailings distributor (44) where the diluted tailings (40) are
distributed throughout the diluent recovery vessel (22). The
diluted tailings (40) are introduced into the diluent recovery
vessel (22) at a feed rate by weight of the diluted tailings
(40).
[0154] The diluted tailings (40) move downward from the tailings
distributor (44) through the interior (28) of the diluent recovery
vessel (22) and form a tailings pool (46) in the tailings pool
section (30) of the diluent recovery vessel (22).
[0155] The interior (28) of the diluent recovery vessel (22) is
maintained at the desired operating pressure for the method. In
some embodiments, the desired operating pressure may be
sub-atmospheric or slightly above atmospheric pressure. In some
embodiments, a suitable operating pressure range for the method may
generally be an absolute pressure between about 20 kPa (about 3
psia) and about 120 kPa (about 17 psia).
[0156] If the hydrocarbon diluent which is contained in the diluted
tailings (40) consists of one or more naphthenic type diluents, the
desired operating pressure for the method may generally be higher
than if the hydrocarbon diluent consists of one or more paraffinic
type diluents. In some embodiments, a desired operating pressure
range for the method in conjunction with naphthenic type diluents
may be an absolute pressure between about 30 kPa (about 4 psia) and
about 120 kPa (about 17 psia). In some embodiments, a desired
operating pressure range for the method in conjunction with
paraffinic type diluents may be an absolute pressure between about
20 kPa (about 3 psia) and about 110 kPa (about 16 psia). In some
embodiments, a desired operating pressure range for the method in
conjunction with a mixture of naphthenic type diluents and
paraffinic type diluents may be a compromise of the two above
ranges.
[0157] In some embodiments, the operating pressure for the method
may be minimized in order to minimize the temperature at which the
method is performed.
[0158] The diluted tailings (40) are subjected to two separate
treatments in the tailings pool (46). First, an amount of steam
(80) is introduced directly into the tailings pool (46) in order to
transfer heat to the diluted tailings (40) and in order to subject
the diluted tailings (40) to steam stripping or steam distillation.
Second, the diluted tailings (40) in the tailings pool are mixed in
order to promote an equilibrium state amongst the liquid and vapour
phases of the components of the diluted tailings (40) and the steam
(80).
[0159] These two treatments are continued for an appropriate
residence time in order to provide an opportunity for the liquid
and vapour phases of the components of the diluted tailings (40)
and the steam (80) to achieve or approach the equilibrium state. In
some embodiments, a suitable residence time of the diluted tailings
(40) in the diluent recovery vessel (22) may be between about 1
minute and about 50 minutes.
[0160] If the diluted tailings (40) are comprised of, consist of,
or consist essentially of a fine mineral material fraction of froth
treatment tailings, the appropriate residence time may be longer
than if the diluted tailings (40) consist of a coarse mineral
material fraction. Similarly, if the hydrocarbon diluent content of
the diluted tailings (40) is greater than about 3 percent by weight
of the diluted tailings (40), the appropriate residence time may be
longer than if the hydrocarbon diluent content of the diluted
tailings (40) is less than about 3 percent by weight of the diluted
tailings (40). The residence time may also be affected by other
factors, including but not limited to the steam addition rate and
the mixing intensity.
[0161] In some embodiments in which the diluted tailings (40) are
comprised of, consist of, or consist essentially of a coarse
mineral material fraction and/or if the hydrocarbon diluent content
of the diluted tailings (40) is less than about 3 percent by weight
of the diluted tailings (40), a suitable residence time of the
diluted tailings (40) in the diluent recovery vessel (22) may be
between about 1 minute and about 20 minutes.
[0162] In some embodiments in which the diluted tailings (40) are
comprised of, consist of, or consist essentially of a fine mineral
material fraction and/or if the hydrocarbon diluent content of the
diluted tailings (40) is greater than about 3 percent by weight of
the diluted tailings (40), a suitable residence time of the diluted
tailings (40) in the diluent recovery vessel (22) may be between
about 1 minute and about 50 minutes.
[0163] Referring to FIG. 1 and FIG. 2, introducing the steam (80)
directly to the tailings pool (46) is comprised of distributing the
steam (80) throughout the tailings pool (46) with the steam
distributor (78). The steam (80) is provided to the steam
distributor (78) by the source of the steam (80) and is introduced
into the tailings pool (46) by the steam distributor (78) at a
steam addition rate by weight of the steam (80). In some
embodiments, the steam addition rate may be dependent upon the feed
rate of the diluted tailings (40) into the diluent recovery vessel
(22). In some embodiments, a suitable steam addition rate range may
be between about 5 percent and about 30 percent of the feed rate.
In some embodiments, a suitable steam addition rate range may be
between about 5 percent and about 15 percent of the feed rate.
[0164] Referring to FIG. 1 and FIG. 2, mixing the diluted tailings
(40) is comprised of stirring the diluted tailings (40) with the
stirrer (90) at a stirring intensity. In some embodiments, a
suitable stirring intensity range may be between about 0.05 watts
per kilogram of the diluted tailings (40) and about 40 watts per
kilogram of the diluted tailings (40). In some embodiments, a
suitable stirring intensity range may be between about 1.5 watts
per kilogram of the diluted tailings (40) and about 10 watts per
kilogram of the diluted tailings (40).
[0165] Referring to FIG. 1 and FIG. 2, mixing the diluted tailings
(40) is further comprised of passing the diluted tailings (40)
through the recirculation circuit (100) at a recirculation rate. In
some embodiments, the recirculation rate may be dependent upon the
feed rate of the diluted tailings (40) into the diluent recovery
vessel (22). In some embodiments, a suitable recirculation rate
range may be between about 5 percent and about 50 percent of the
feed rate. In some embodiments, a suitable recirculation rate range
may be between about 10 percent and about 20 percent of the feed
rate.
[0166] Mixing the diluted tailings (40) may assist in distributing
the steam (80) throughout the tailings pool (46) by breaking the
steam (80) into smaller droplets and/or dispersing the steam (80)
throughout the diluted tailings (40).
[0167] The combination of introducing the steam (80) into the
tailings pool (46) and mixing the diluted tailings (40) which are
contained in the tailings pool (46) may result in the formation
from the diluted tailings (40) of foam above the tailings pool
(46). The presence of foam may be detrimental to the performance of
the method.
[0168] Referring to FIG. 1 and FIG. 2, the method is further
comprised of providing the foam breaking device (110) in the
interior (28) of the diluent recovery vessel (22).
[0169] Referring to FIG. 1, one type of foam breaking device (110)
is comprised of the foam breaker (112) which is rotatable with the
stirrer (90) by the stirring shaft (92) and the stirring motor
(96). The rotation of the foam breaker (112) breaks down the foam
which is formed from the diluted tailings (40) and inhibits the
foam from moving upward in the diluent recovery vessel (22).
[0170] Referring to FIG. 2, an alternate type of foam breaking
device (110) is comprised of the increased foam breaking horizontal
dimension and/or increased foam breaking cross-sectional area
relative to the tailings pool horizontal dimension and/or the
tailings pool cross-sectional area respectively. The presence of
the increased foam breaker horizontal dimension and/or the
increased foam breaker cross-sectional area inhibits the foam from
moving upward in the diluent recovery vessel (22) and appears to
inhibit the stability of the foam.
[0171] As a result of the combined effects of introducing the steam
(80) directly into the tailings pool (46), mixing the diluted
tailings (40) which are contained in the tailings pool (46), and
providing a suitable residence time of the diluted tailings (40) in
the diluent recovery vessel (22) to promote an equilibrium state
amongst the liquid and vapour components of the diluted tailings
(40) and the steam (80), the diluted tailings (40) are separated
into the recovered diluent component (50) and the diluent recovered
tailings component (70).
[0172] The recovered diluent component (50) moves upward through
the diluent recovery vessel (22) to the recovered diluent component
outlet (48) where the recovered diluent component (50) is recovered
from the diluent recovery vessel (22) and passed to the condensing
apparatus (52). In the condensing apparatus (52), the recovered
diluent component (50) is condensed and separated into the
recovered hydrocarbon diluent (60) and the recovered water (62).
The recovered hydrocarbon diluent (60) may be recycled for use in a
bitumen froth treatment process. The recovered water (62) may be
recycled for use in a bitumen froth treatment process or some other
process.
[0173] The diluent recovered tailings component (70) are retained
in the tailings pool section (30) of the diluent recovery vessel
(22) until the diluent recovered tailings component (70) is
recovered from the diluent recovery vessel (22) via the diluent
recovered tailings component outlet (68) by draining, pumping,
augering or otherwise withdrawing the diluent recovered tailings
component (70) from the diluent recovery vessel (22). After it is
recovered from the diluent recovery vessel (22), the diluent
recovered tailings component (70) may be further treated or may be
disposed of.
Examples
[0174] Bench scale experimental testing of an embodiment of the
method of the invention was conducted using several different types
of diluted tailings. The bench scale experimental testing was
conducted as a batch implementation of the method of the
invention.
[0175] FIG. 3 is a table providing data from the bench scale
experimental testing in which the diluted tailings consisted of
either a heavy mineral concentrate obtained from froth treatment
tailings ("HMC"), a washed heavy mineral concentrate
("HMC-washed"), a fine mineral material fraction obtained from
froth treatment tailings ("Fines"), or a dewatered fine mineral
material fraction ("Fines-dewatered").
[0176] FIG. 4 is a graph presenting data resulting from the bench
scale experimental testing in which the diluted tailings consisted
of a heavy mineral concentrate ("HMC") or a washed heavy mineral
concentrate ("HMC-washed") obtained from froth treatment tailings.
The data points presented in FIG. 4 represent the arithmetic
average of data for as many as four test runs. The error bars
represent the standard deviations of the data which provided the
data points.
[0177] FIG. 5 is a graph presenting data resulting from the bench
scale experimental testing in which the diluted tailings consisted
of a fine mineral material fraction ("Fines") obtained from froth
treatment tailings. The data points presented in FIG. 5 represent
discrete data for a number of individual test runs.
[0178] The HMC was comprised of an aqueous slurry (containing about
50 wt % solid mineral material) of a coarse mineral material
fraction of froth treatment tailings in which heavy minerals were
concentrated. The Fines were comprised of an aqueous slurry
(containing about 10 wt % solid mineral material) of a fine mineral
material fraction of froth treatment tailings of the type which
could be produced by separating froth treatment tailings by
cycloning.
[0179] The washed heavy mineral concentrate ("HMC-washed") was a
heavy mineral concentrate which was washed with water. Referring to
FIG. 3, washing the heavy mineral concentrate effectively reduced
the concentration of the hydrocarbon diluent in the heavy mineral
concentrate via rejection of fine mineral material which is coated
with hydrocarbon diluent.
[0180] The dewatered fine mineral material fraction
("Fines-dewatered") was a fine mineral material fraction from which
some water had been removed. Referring to FIG. 3, dewatering the
fine mineral material fraction effectively increased the
concentration of the hydrocarbon diluent in the fine mineral
material fraction due to the removal of the water.
[0181] The hydrocarbon diluent for all of the bench scale
experimental testing reported in FIGS. 3-5 consisted of naphtha.
Referring to FIG. 3, the hydrocarbon diluent content for the
HMC/HMC-washed samples ranged between about 0.76 wt % and about
1.47 wt % and the hydrocarbon diluent content for the
Fines/Fines-dewatered samples ranged between about 9.31 wt % and
49.28 wt %. As a comparison, it is noted that a typical naphtha
recovery unit (NRU) or tailings solvent recovery unit (TSRU)
conventionally processes feed material which has a hydrocarbon
diluent content which is in the order of about 5 wt %.
[0182] The apparatus (20) for the experimental testing was
comprised of a stainless steel tube as the diluent recovery vessel
(22). The tube had an outside diameter (OD) of about 5 cm (about 2
inches), a length of about 40 cm (about 16 inches), and was
provided with closure fittings at each end to facilitate quick
assembly and disassembly, addition or removal of the contents of
the tube, and cleaning of the tube as necessary.
[0183] The apparatus (20) for the experimental testing was further
comprised of a stirrer (90) for mixing the diluted tailings (40)
and a recovered diluent component outlet (48) for recovering the
recovered diluent component (50) from the diluent recovery vessel
(22).
[0184] The diluent recovery vessel (22) was heated to the desired
operating temperatures using a test stand furnace and heating tape.
The test stand furnace was used to keep the top of the diluent
recovery vessel (22) and the recovered diluent component outlet
(48) at a temperature slightly greater than 100 degrees Celsius to
prevent condensation of the recovered diluent component (50) within
the diluent recovery vessel (22) before reaching the condensing
apparatus (52) and to minimize heat losses from the diluent
recovery vessel (22) during steam stripping.
[0185] Three designs for the steam distributor (78) were evaluated
during the experimental testing. A first design was comprised of a
0.3175 cm (0.125 inch) thick porous foam metal disk. A second
design was comprised of a 0.159 cm (0.0625 inch) sintered metal
disk. A third design was comprised of a dual-screen (25 micrometer
opening) configuration. Results from the experimental testing
suggested that the first design and the third design were less
susceptible to plugging and a resulting undesirable increased
pressure drop across the steam distributor (78) than was the second
design.
[0186] Two options for mitigating foaming were evaluated during the
experimental testing.
[0187] A first foam breaking option utilized a one inch diameter
brush attached to the stirring shaft (92) of the stirrer (90) at a
location immediately below the recovered diluent component outlet
(48). Tests performed in the diluent recovery vessel (22) out of
the test stand under foaming conditions demonstrated that the brush
could effectively break up the foam and prevent the foam from
rising further in the diluent recovery vessel (22). The first
option was similar to the foam breaking device (110) depicted in
FIG. 1.
[0188] A second foam breaking option utilized a beaker having a
diameter of about 12 cm (about 4.5 inches). The beaker was filled
with an equivalent amount of diluted tailings (40) as was contained
in the diluent recovery vessel (22) during the experimental
testing. The beaker was placed on a hot plate and the temperature
of the diluted tailings (40) was increased. It was observed that as
the temperature of the diluted tailings (40) increased, an
increasing amount of foam would be produced and would gradually
rise in the beaker. The foam stopped rising at a level of about 40
percent of the beaker height. The size of the beaker was selected
to simulate the foam breaking device (110) depicted in FIG. 2,
having a larger diameter freeboard section as compared with the
diluent recovery vessel (22) used in the experimental testing.
[0189] The experimental testing of the method of the invention was
generally conducted according to the following procedure: [0190]
(a) the test stand furnace and heating tape and a steam generator
furnace were switched on and set to the desired temperatures;
[0191] (b) once the steam generator furnace reached its desired
temperature, a water pump was switched on to initiate steam
generation, with the flow of steam (80) being directed to a bypass
line in order to bypass the diluent recovery vessel (22); [0192]
(c) the diluent recovery vessel (22) was preloaded with a desired
batch amount of diluted tailings (40) and installed in the test
unit; [0193] (d) once the test stand furnace reached the desired
100 degree Celsius temperature, the flow of steam (80) was
redirected from the bypass line to the diluent recovery vessel (22)
and stirring of the diluted tailings (40) was commenced; [0194] (e)
the volumes of the recovered hydrocarbon diluent (60) and the
recovered water (62) which were separated from the recovered
diluent component (50) in the condensing apparatus (52) were
measured as a function of time; [0195] (f) the flow of steam (80)
and the mixing of the diluted tailings (40) continued until the
rate of condensation of the recovered hydrocarbon diluent (60) in
the condensing apparatus (52) decreased to nearly zero or until a
desired duration of the flow of steam (80) and mixing of the
diluted tailings (40) following an initial condensation of the
recovered hydrocarbon diluent (60) was attained, at which time the
flow of steam (80) and the mixing of the diluted tailings (40)
ceased and the steam (80) was again diverted to the bypass line;
[0196] (g) after completion of the test, all of the inlets and
outlets in the diluent recovery vessel (22) were capped off and the
diluent recovery vessel (22) was removed from the test stand;
[0197] (h) after the diluent recovery vessel (22) cooled to the
ambient temperature, it was opened and the recovered diluent
tailings component (70) contained in the diluent recovery vessel
(22) was removed and prepared for analysis by centrifuging and
decanting; and [0198] (i) the separated solid and liquid components
of the recovered diluent tailings component (70) were weighed and
analyzed for water content, hydrocarbon diluent content, and
bitumen content.
[0199] As indicated above, FIGS. 3-5 present data resulting from
the bench scale experimental testing.
[0200] Referring to FIGS. 3-5, it is noted that the operating
parameters for the testing were generally as follows:
[0201] Operating Temperature: about 99-105 degrees Celsius
[0202] Operating Pressure: about 1-1.2 atmosphere absolute
[0203] Steam Addition Rate: about 0.59-1.5 g/min
[0204] Steam-To-Feed Ratio: about 0.03-0.40
[0205] The following is noted from observations made during the
experimental testing and from a review of FIGS. 3-5: [0206] (a) the
recovery of the hydrocarbon diluent from the HMC and HMC-washed
diluted tailings (40) in the experimental testing resulted in a
hydrocarbon diluent content in the diluent recovered tailings
component (70) of between about 0.072 wt % and about 0.152 wt %,
representing a hydrocarbon diluent recovery of between about 89.1
percent and about 91.7 percent; [0207] (b) the recovery of the
hydrocarbon diluent from the Fines and Fines-dewatered diluted
tailings (40) in the experimental testing resulted in a hydrocarbon
diluent content in the diluent recovered tailings component (70) of
between about 0.050 wt % and about 0.146 wt %, representing a
hydrocarbon diluent recovery of between about 98.4 percent and
about 99.8 percent; [0208] (c) the data pertaining to the
processing of the Fines-dewatered diluted tailings (40) suggests
that increasing the solids content and the hydrocarbon diluent
content of the diluted tailings (40) to as high as 49.28 percent
had no detrimental effect on either the extent of recovery of the
hydrocarbon diluent from the diluted tailings (40) or upon the
hydrocarbon diluent content of the diluent recovered tailings
component (70); [0209] (d) at moderate steam addition rates (0.59
g/min and 0.75 g/min), a residence time of about 15 to 20 minutes
was necessary to obtain near complete recovery (i.e., greater than
about 80 percent) of the hydrocarbon diluent from the HMC and
HMC-washed diluted tailings (40), while a residence time of about
40-50 minutes was necessary to obtain near complete recovery (i.e.,
greater than about 80 percent) of the hydrocarbon diluent from the
Fines and Fines-dewatered diluted tailings (40); [0210] (e) at a
relatively high steam addition rate (1.5 g/min), a residence time
of less than 5 minutes was necessary to obtain a near complete
recovery (i.e., greater than about 80 percent) of the hydrocarbon
diluent from HMC diluted tailings (40); [0211] (f) the hydrocarbon
diluent contents of the Fines and Fines-dewatered diluted tailings
(40) were significantly higher (by nearly an order of magnitude)
than the hydrocarbon diluent contents of the HMC and HMC-washed
diluted tailings (40); [0212] (g) having regard to Points (d), (e)
and (f) above, the residence time necessary to obtain near complete
recovery (i.e., greater than about 80 percent) of the hydrocarbon
diluent from diluted tailings (40) using the method of the
invention may be dependent upon the time required to achieve or
approach an equilibrium state amongst the liquid and vapour phases
of the components of the diluted tailings (40) and the steam (80);
[0213] (h) having regard to Points (d), (e) and (f) above, the
residence time necessary to obtain near complete recovery (i.e.,
greater than about 80 percent) of the hydrocarbon diluent from
diluted tailings (40) using the method of the invention may be
dependent upon the composition of the diluted tailings (40), upon
the hydrocarbon diluent content of the diluted tailings (40), upon
the steam addition rate, upon the mixing intensity, or upon a
combination of these and/or other factors; and [0214] (i) having
regard to Point (e) above, the residence time necessary to obtain
near complete recovery (i.e., greater than about 80 percent) of the
hydrocarbon diluent from diluted tailings (40) using the method of
the invention may be dependent upon the time required to achieve or
approach an equilibrium state amongst the liquid and vapour phases
of the components of the diluted tailings (40) and the steam (80),
which in turn may be dependent upon the composition of the diluted
tailings (40), upon the hydrocarbon diluent content of the diluted
tailings (40), upon the steam addition rate, upon the mixing
intensity, or upon a combination of these and/or other factors.
[0215] In this document, the word "comprising" is used in its
non-limiting sense to mean that items following the word are
included, but items not specifically mentioned are not excluded. A
reference to an element by the indefinite article "a" does not
exclude the possibility that more than one of the elements is
present, unless the context clearly requires that there be one and
only one of the elements.
* * * * *