Note: Descriptions are shown in the official language in which they were submitted.
CA 02839509 2014-01-15
METHODS FOR SEPARATING A FEED MATERIAL DERIVED
FROM A PROCESS FOR RECOVERING BITUMEN FROM OIL SANDS
TECHNICAL FIELD
Separation methods for separating a feed material comprising solid mineral
material, water and bitumen, wherein the feed material is derived from a
process for recovering
bitumen from oil sands.
BACKGROUND OF THE INVENTION
Oil sands is essentially comprised of a matrix of bitumen, solid mineral
material
and water.
The bitumen component of oil sands 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 sands. For example, bitumen has been defined by the United Nations
Institute for Training
and Research as a hydrocarbon with a viscosity greater than 104 mPa s (at
deposit temperature)
and a density greater than 1000 kg/m3 at 15.6 degrees Celsius.
The solid mineral material component of oil sands typically consists of sand,
rock,
silt and clay. Solid mineral material may be present in oil sands 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 sands as
coarse mineral
material, while silt and clay are generally present in oil sands as fine
mineral material.
A typical deposit of oil sands 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.
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Water based technologies are typically used to extract bitumen from oil sands
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.
In a typical water based oil sands extraction process, the oil sands ore is
first mixed
with water to form an aqueous slurry. The slurry is then processed to release
bitumen from within
the oil sands 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.
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.
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.
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 by solvent extraction in one or more solvent extraction
apparatus in order to produce
the bitumen product and the froth treatment tailings. Exemplary solvent
extraction apparatus
include gravity settling vessels, inclined plate separators and centrifuges.
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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.
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.
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.
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.
Froth treatment tailings therefore typically contain solid mineral material,
water,
froth treatment diluent, and small amounts 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).
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Much of the residual froth treatment diluent remaining in froth treatment
tailings is
typically recovered from the froth treatment tailings in a tailings solvent
recovery unit (TSRU).
The froth treatment tailings (including the tailings bitumen) are then
typically disposed of in a
tailings pond.
A significant amount of bitumen from the original oil sands ore is therefore
typically lost to the froth treatment tailings as residual bitumen. There are
both environmental
incentives and economic incentives for recovering all or a portion of this
residual bitumen.
In addition, the solid mineral material which is included in the froth
treatment
tailings 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
contained in typical froth treatment tailings may include titanium bearing
minerals such as rutile
(Ti02), anatase (Ti02), ilmenite (FeTiO3) and leucoxene (typically an
alteration product of
ilmenite) and zirconium bearing minerals such as zircon (ZrSiO4). Titanium and
zirconium
bearing minerals are typically used as feedstocks for manufacturing engineered
materials due to
their inherent properties.
Although oil sands 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 sands 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.
Froth treatment tailings may be further processed to recover bitumen and/or
heavy
minerals therefrom. Froth treatment tailings may be further processed as
"whole tailings", or froth
treatment tailings may be separated and fractions of the separated froth
treatment tailings may be
further processed. Examples in the art of methods for further processing froth
treatment tailings to
recover bitumen and/or heavy minerals therefrom may be found in Canadian
Patent No. 2,426,113
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(Reeves et al), Canadian Patent Application No. 2,548,006 (Erasmus et al), and
Canadian Patent
Application No. 2,662,346 (Moran et al).
There remains a need in the art for methods for separating feed materials
comprising solid mineral material, water and bitumen, wherein the feed
materials are derived from
a process for recovering bitumen from oil sands, and wherein representative
feed materials may
include (but are not limited to) a bitumen froth, whole froth treatment
tailings, and/or fractions of
whole froth treatment tailings.
SUMMARY OF THE INVENTION
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.
In this document, "gravity settling" means an operation in which components of
a
mixture are separated using gravity, and is therefore distinguished from other
separation
operations such as molecular sieve processes, absorption processes, adsorption
processes,
magnetic processes, electrical processes, enhanced gravity settling processes,
etc.
In this document, "gravity settler" includes a gravity settling vessel, an
inclined
plate separator, a rotary disc contactor, a thickener, and any other suitable
apparatus which
facilitates gravity settling, with or without the use of process aids such as
flocculants and
demulsifiers. In this document, gravity settler also includes a mixing
apparatus which may be
used in association with the gravity settling operation.
In this document, "gravity settling vessel" means a tank or other vessel into
which a
mixture may be introduced in order to facilitate separation of the mixture
using gravity, but is
distinguishable from an inclined plate separator. A gravity settling vessel
may have any shape,
size and/or configuration which is suitable for achieving gravity separation.
A gravity settling
vessel may or may not include internal structures such as weirs, sumps,
launders, baffles,
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distributors, etc. and may or may not include internal mechanical devices such
as rakes,
conveyors, augers, etc.
In this document, "inclined plate separator" means an apparatus which is
comprised
of a plurality of stacked inclined plates onto which a mixture to be separated
may be introduced so
that the mixture passes along the plates in order to achieve separation of
components of the
mixture, and is distinguishable from a gravity settling vessel.
In this document, "enhanced gravity separation" means an operation in which
components of a mixture are separated using centrifugal acceleration or
centripetal acceleration
resulting from rotational movement of the mixture, and is therefore
distinguished from gravity
separation processes.
In this document, "enhanced gravity separator" or "enhanced gravity separation
apparatus" includes a centrifuge, a hydrocyclone and any other suitable
apparatus which facilitates
enhanced gravity separation.
In this document, "solvent extraction" means an operation in which components
of
a mixture are separated by adding to the mixture a suitable liquid solvent
which dissolves and/or
dilutes one or more components of the mixture, thereby facilitating separation
of components of
the mixture.
In this document, "solvent extraction apparatus" includes gravity settlers
(including
without limitation, gravity settling vessels, inclined plate separators, and
rotary disc contactors)
and enhanced gravity separators (including without limitation, centrifuges and
hydrocyclones).
In this document, "froth treatment diluent" means any substance containing one
or
more hydrocarbon compounds and/or substituted hydrocarbon compounds which is
suitable for
use in diluting and/or dissolving bitumen froth in a froth treatment process.
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 the practice of the invention.
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In this document, "diluent" may include a froth treatment diluent and/or a
hydrocarbon diluent.
In this document, "naphthenic type diluent" means a froth treatment diluent or
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.
In this document, "naphthenic froth treatment process" means a froth treatment
process which uses a sufficient amount of one or more naphthenic type diluents
so that the froth
treatment process is recognized in the art as a naphthenic froth treatment
process as distinguished
from a paraffinic froth treatment process.
In this document, "paraffinic type diluent" means a froth treatment diluent or
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.
In this document, "paraffinic froth treatment process" means a froth treatment
process which uses a sufficient amount of one or more paraffinic type diluents
so that the froth
treatment process is recognized in the art as a paraffinic froth treatment
process as distinguished
from a naphthenic froth treatment process.
In this document, "froth flotation" means an operation in which components of
a
mixture are separated by passing a gas through the mixture so that the gas
causes one or more
components of the mixture to float to the top of the mixture and form a froth.
In this document,
froth flotation may be performed using flotation cells or tanks, flotation
columns or any other
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suitable froth flotation apparatus, which may or may not include agitators or
mixers, and froth
flotation may include the use of flotation aids, including without limitation,
surfactants and
frothing agents.
In this document, "heavy minerals" includes solid mineral material which has a
specific gravity greater than that of quartz (i.e., a specific gravity greater
than about 2.65),
including but not limited to titanium bearing minerals such as rutile (Ti02),
anatase (TiO2),
ilmenite (FeTiO3) and leucoxene (typically an alteration product of ilmenite)
and zirconium
bearing minerals such as zircon (ZrSiO4).
The present invention is directed at methods for separating a feed material
comprising solid mineral material, water and bitumen, wherein the feed
material is derived from a
process for recovering bitumen from oil sands. The feed material may consist
of, may consist
essentially of, or may be comprised of a bitumen froth, whole froth treatment
tailings, a fraction of
whole froth treatment tailings, and/or any other suitable material derived
from oil sands.
The methods of the invention are solvent extraction separation methods which
are
performed in one or more solvent extraction stages. As a result, the feed
material may be further
comprised of a hydrocarbon diluent, and/or the methods may be comprised of
introducing a
hydrocarbon diluent into one or more of the solvent extraction stages.
In all aspects of the invention, the methods of the invention may be comprised
of
any number of solvent extraction stages. In some embodiments of all aspects,
the methods may be
comprised of more than three solvent extraction stages. In some embodiments of
all aspects, the
methods may be comprised of a first solvent extraction stage and a final
solvent extraction stage.
In some embodiments of all aspects, the methods may be comprised of one or
more intermediate
solvent extraction stages.
In some embodiments of all aspects of the invention, the methods of the
invention
may be performed in a countercurrent manner. In some embodiments of all
aspects, an extract
may be produced as an overflow product in a first solvent extraction stage and
a raffinate may be
produced as an underflow product in a final solvent extraction stage.
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In all aspects of the invention, the solvent extraction feed material may be
any
suitable material derived from oil sands. In some embodiments of all aspects,
the solvent
extraction feed material may consist of, may consist essentially of, or may be
comprised of a
bitumen froth. In some embodiments of all aspects, the solvent extraction feed
material may
consist of, may consist essentially of, or may be comprised of whole froth
treatment tailings. In
some embodiments of all aspects, the solvent extraction feed material may
consist of, may consist
essentially of, or may be comprised of a coarse mineral material fraction of
whole froth treatment
tailings. In some embodiments of all aspects, the solvent extraction feed
material may consist of,
may consist essentially of, or may be comprised of a fine mineral material
fraction of whole froth
treatment tailings.
In all aspects of the invention, the solvent extraction stages may be
performed using
any suitable solvent extraction apparatus. The solvent extraction apparatus
may be similar in each
solvent extraction stage or the solvent extraction apparatus may be different
in some or all of the
solvent extraction stages. In some embodiments of all aspects, the solvent
extraction apparatus
may be comprised of a mixing apparatus for mixing and/or conditioning the
solvent extraction
feed material.
In some embodiments of all aspects of the invention, the methods may be
further
comprised of introducing an amount of a hydrocarbon diluent into one or more
of the solvent
extraction stages. In some embodiments of all aspects, the hydrocarbon diluent
may be introduced
into a final solvent extraction stage.
In some embodiments of all aspects of the invention, the hydrocarbon diluent
may
consist of, may consist essentially of, or may be comprised of a paraffinic
type diluent. In some
embodiments of all aspects, the hydrocarbon diluent may consist of, may
consist essentially of, or
may be comprised of a naphthenic type diluent.
In a first exemplary aspect, the invention is a separation method, the method
comprising:
(a) introducing a first solvent extraction feed material into a
first solvent extraction
stage, wherein the first solvent extraction feed material is comprised of
solid
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mineral material, water and bitumen, and wherein the first solvent extraction
feed
material is derived from a process for recovering bitumen from oil sands;
(b) allowing the first solvent extraction feed material to separate in the
first solvent
extraction stage into an underflow zone and an overflow zone;
(c) withdrawing a first stage underflow product from the underflow zone of
the first
solvent extraction stage;
(d) withdrawing a first stage overflow product from the overflow zone of
the first
solvent extraction stage;
(e) withdrawing a first intra-stage recycle component from the overflow
zone of the
first solvent extraction stage; and
(f) combining the first intra-stage recycle component with the first
solvent extraction
feed material.
In some embodiments, the first solvent extraction feed material may be
comprised
of an upstream underflow product of an upstream solvent extraction stage.
In some embodiments, the first exemplary aspect may further comprise:
(a) introducing the first stage underflow product into a second solvent
extraction stage
as a second solvent extraction feed material;
(b) allowing the second solvent extraction feed material to separate in the
second
solvent extraction stage into an underflow zone and an overflow zone;
(c) withdrawing a second stage underflow product from the underflow zone of
the
second solvent extraction stage; and
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(d) withdrawing a second stage overflow product from the overflow
zone of the second
solvent extraction stage.
In some embodiments, the first exemplary aspect may further comprise:
(a) withdrawing a second intra-stage recycle component from the overflow
zone of the
second solvent extraction stage; and
(b) combining the second intra-stage recycle component with the second
solvent
extraction feed material.
In some embodiments, the first exemplary aspect may be further comprised of
introducing the second stage overflow product into the first solvent
extraction stage.
In some embodiments, the first exemplary aspect may further comprise:
(a) introducing the second stage underflow product into a third
solvent extraction stage
as a third solvent extraction feed material;
(b) allowing the third solvent extraction feed material to separate in the
third solvent
extraction stage into an underflow zone and an overflow zone;
(c) withdrawing a third stage underflow product from the underflow zone of
the third
solvent extraction stage; and
(d) withdrawing a third stage overflow product from the overflow zone of
the third
solvent extraction stage.
In some embodiments, the first exemplary aspect may further comprise:
(a) withdrawing a third intra-stage recycle component from the
overflow zone of the
third solvent extraction stage; and
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(b) combining the third intra-stage recycle component with the
third solvent extraction
feed material.
In some embodiments, the first exemplary aspect may be further comprised of
introducing the third stage overflow product into the second solvent
extraction stage.
In a second exemplary aspect, the invention is a separation method for
producing
an extract and a raffinate from a solvent extraction feed material comprising
solid mineral
material, water and bitumen, wherein the solvent extraction feed material is
derived from a process
for recovering bitumen from oil sands, wherein the separation method is
comprised of a plurality
of solvent extraction stages, wherein each of the solvent extraction stages
produces from a stage
solvent extraction feed material an overflow product from an overflow zone and
an underflow
product from an underflow zone, and wherein in at least one of the solvent
extraction stages a
stage intra-stage recycle component is produced from the overflow zone and is
recycled to the
solvent extraction stage.
In some embodiments of the first exemplary aspect and the second exemplary
aspect, an intra-stage recycle component may be produced in each of the
solvent extraction stages
and may be recycled back to the solvent extraction stage.
A ratio by weight of the intra-stage recycle component to the solvent
extraction
feed material provides an intra-stage recycle ratio. The intra-stage recycle
ratio may be similar in
each solvent extraction stage or may be different in some or all of the
solvent extraction stages. In
some embodiments, the intra-stage recycle ratio may be between about 0.1 and
1.5. In some
embodiments, the intra-stage recycle ratio may be between about 0.5 and 1.
In a third exemplary aspect, the invention is a separation method, the method
comprising:
(a) introducing a first solvent extraction feed material into a first
solvent extraction
stage, wherein the first solvent extraction feed material is comprised of
solid
mineral material, water and bitumen, and wherein the first solvent extraction
feed
material is derived from a process for recovering bitumen from oil sands;
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(b) allowing the first solvent extraction feed material to
separate in the first solvent
extraction stage into an underflow zone and an overflow zone;
(c) withdrawing a first stage underflow product from the underflow zone of
the first
solvent extraction stage at a first stage underflow product withdrawal rate;
(d) withdrawing a first stage overflow product from the overflow zone of
the first
solvent extraction stage at a first stage overflow product withdrawal rate;
(e) introducing the first stage underflow product into a second solvent
extraction stage
as a second solvent extraction feed material;
(0 allowing the second solvent extraction feed material to
separate in the second
solvent extraction stage into an underflow zone and an overflow zone;
(g) withdrawing a second stage underflow product from the underflow zone of
the
second solvent extraction stage at a second stage underflow product withdrawal
rate, wherein the first stage underflow product withdrawal rate is greater
than the
second stage underflow product withdrawal rate;
(h) withdrawing a second stage overflow product from the overflow zone of
the second
solvent extraction stage at a second stage overflow product withdrawal rate;
and
(i) introducing the second stage overflow product into the first solvent
extraction
stage.
In a fourth exemplary aspect, the invention is a separation method, the method
comprising:
(a) introducing a first solvent extraction feed material into a
first solvent extraction
stage, wherein the first solvent extraction feed material is comprised of
solid
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mineral material, water and bitumen, and wherein the first solvent extraction
feed
material is derived from a process for recovering bitumen from oil sands;
(b) allowing the first solvent extraction feed material to separate in the
first solvent
extraction stage into an underflow zone and an overflow zone;
(c) withdrawing a first stage underflow product from the underflow zone of
the first
solvent extraction stage at a first stage underflow product withdrawal rate;
(d) withdrawing a first stage overflow product from the overflow zone of
the first
solvent extraction stage at a first stage overflow product withdrawal rate;
(e) introducing the first stage underflow product into a second
solvent extraction stage
as a second solvent extraction feed material;
(0 allowing the second solvent extraction feed material to
separate in the second
solvent extraction stage into an underflow zone and an overflow zone;
(g) withdrawing a second stage underflow product from the underflow zone of
the
second solvent extraction stage at a second stage underflow product withdrawal
rate;
(h) withdrawing a second stage overflow product from the overflow zone of
the second
solvent extraction stage at a second stage overflow product withdrawal rate;
introducing the second stage overflow product into the first solvent
extraction
stage;
(i) introducing the second stage underflow product into a third solvent
extraction stage
as a third solvent extraction feed material;
(k) allowing the third solvent extraction feed material to
separate in the third solvent
extraction stage into an underflow zone and an overflow zone;
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(1)
withdrawing a third stage underflow product from the underflow zone of
the third
solvent extraction stage at a third stage underflow product withdrawal rate;
(m) withdrawing a third stage overflow product from the overflow zone of the
third
solvent extraction stage at a third stage overflow product withdrawal rate;
and
(n)
introducing the third stage overflow product into the second solvent
extraction
stage;
wherein at least one of the first stage underflow product withdrawal rate and
the second stage
underflow product withdrawal rate is greater than the third stage underflow
product withdrawal
rate.
In a fifth exemplary aspect, the invention is a separation method for
producing an
extract and a raffinate from a solvent extraction feed material comprising
solid mineral material,
water and bitumen, wherein the solvent extraction feed material is derived
from a process for
recovering bitumen from oil sands, wherein the separation method is comprised
of a plurality of
solvent extraction stages, wherein each of the solvent extraction stages
produces an overflow
product and an underflow product, wherein the extract is produced as the
overflow product in a
first solvent extraction stage, wherein the raffinate is produced as the
underflow product in a final
solvent extraction stage, and wherein an underflow product withdrawal rate of
the underflow
product produced in at least one of the solvent extraction stages other than
the final solvent
extraction stage is greater than the underflow product withdrawal rate of the
raffinate.
In the third exemplary aspect, the fourth exemplary aspect and the fifth
exemplary
aspect, an underflow product withdrawal rate of the underflow product produced
in at least one of
the solvent extraction stages other than a final solvent extraction stage is
greater than the
underflow product withdrawal rate of the underflow product withdrawal rate
produced in the final
solvent extraction stage. In the third exemplary aspect, the fourth exemplary
aspect and the fifth
exemplary aspect, a differential is therefore provided between the underflow
product withdrawal
rate in at least of the solvent extraction stages and the underflow product
withdrawal rate in the
final solvent extraction stage.
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In some embodiments of the third exemplary aspect, the fourth exemplary aspect
and the fifth exemplary aspect, the differential between the underflow product
withdrawal rate in
at least one of the solvent extraction stages and the underflow product
withdrawal rate in the final
solvent extraction stage may be no greater than about the first stage overflow
product withdrawal
rate. In some embodiments of the third exemplary aspect, the fourth exemplary
aspect and the
fifth exemplary aspect, the differential between the underflow product
withdrawal rate in at least
one of the solvent extraction stages and the underflow product withdrawal rate
in the final solvent
extraction stage may be no greater than about an introduction rate of a
hydrocarbon diluent into
the solvent extraction stages.
In some embodiments of the third exemplary aspect, the differential between
the
first stage underflow product withdrawal rate and the second stage underflow
product withdrawal
rate may be no greater than about the first stage overflow product withdrawal
rate. In some
embodiments of the third exemplary aspect, the differential between the first
stage underflow
product withdrawal rate and the second stage underflow product withdrawal rate
may be no
greater than about an introduction rate of a hydrocarbon diluent into the
solvent extraction stages.
In some embodiments of the fourth exemplary aspect, the first stage underflow
product withdrawal rate may be greater than the third stage underflow product
withdrawal rate. In
some embodiments of the fourth exemplary aspect, the second stage underflow
product
withdrawal rate may be greater than the third stage underflow product
withdrawal rate.
In some embodiments of the fourth exemplary aspect, the differential between
the
first stage underflow product withdrawal rate and the third stage underflow
product withdrawal
rate may be no greater than about the first stage overflow product withdrawal
rate. In some
embodiments of the fourth exemplary aspect, the differential between the first
stage underflow
product withdrawal rate and the third stage underflow product withdrawal rate
may be no greater
than about an introduction rate of a hydrocarbon diluent into the solvent
extraction stages.
In some embodiments of the fourth exemplary aspect, the differential between
the
second stage underflow product withdrawal rate and the third stage underflow
product withdrawal
rate may be no greater than about the first stage overflow product withdrawal
rate. In some
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CA 02839509 2014-01-15
embodiments of the fourth exemplary aspect, the differential between the
second stage underflow
product withdrawal rate and the third stage underflow product withdrawal rate
may be no greater
than an introduction rate of a hydrocarbon diluent into the solvent extraction
stages.
In some embodiments of the fifth exemplary aspect, the first stage underflow
product withdrawal rate may be greater than the final stage underflow product
withdrawal rate. In
some embodiments of the fifth exemplary aspect, an intermediate stage
underflow product
withdrawal rate may be greater than the final stage underflow product
withdrawal rate.
In some embodiments of the fifth exemplary aspect, the differential between
the
first stage underflow product withdrawal rate and the final stage underflow
product withdrawal
rate may be no greater than about the first stage overflow product withdrawal
rate. In some
embodiments of the third exemplary aspect, the differential between the first
stage underflow
product withdrawal rate and the final stage underflow product withdrawal rate
may be no greater
than an introduction rate of a hydrocarbon diluent into the solvent extraction
stages.
In some embodiments of the fifth exemplary aspect, the differential between
the
intermediate stage underflow product withdrawal rate and the final stage
underflow product
withdrawal rate may be no greater than about the first stage overflow product
withdrawal rate. In
some embodiments of the third exemplary aspect, the differential between the
intermediate stage
underflow product withdrawal rate and the final stage underflow product
withdrawal rate may be
no greater than an introduction rate of a hydrocarbon diluent into the solvent
extraction stages.
In some embodiments of the third exemplary aspect, the fourth exemplary aspect
and the fifth exemplary aspect, the differential between the underflow
component withdrawal rates
may be any amount which permits effective management of the solvent extraction
stages. In some
embodiments of the third exemplary aspect, the fourth exemplary aspect and the
fifth exemplary
aspect, the differential between the underflow component withdrawal rates may
be greater or even
much greater than the first stage overflow product withdrawal rate. In some
embodiments of the
third exemplary aspect, the fourth exemplary aspect and the fifth exemplary
aspect, the differential
between the underflow component withdrawal rates may be greater than or even
much greater than
the introduction rate of the hydrocarbon diluent into the solvent extraction
stages. In some
embodiments, however, differentials above a threshold may result in
difficulties in balancing the
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CA 02839509 2014-01-15
interfaces between the overflow zones and the underflow zones in the solvent
extraction apparatus
and may negatively effect the quality of the extract which is produced by the
solvent extraction.
BRIEF DESCRIPTION OF DRAWINGS
Embodiments of the invention will now be described with reference to the
accompanying drawings, in which:
Figure 1 is a schematic process flow diagram depicting exemplary embodiments
of
the methods of the invention.
Figure 2 is a material balance for a pilot plant test of a portion of the
process flow
diagram depicted in Figure 1, in which the feed material is derived from a
fine mineral material
fraction of froth treatment tailings.
Figure 3 is a material balance for a pilot plant test of a portion of the
process flow
diagram depicted in Figure I, in which the feed material is derived from a
coarse mineral material
fraction of froth treatment tailings.
DETAILED DESCRIPTION
The present invention is directed at methods for separating a feed material
comprising solid mineral material, water and bitumen, wherein the feed
material is derived from a
process for recovering bitumen from oil sands. The feed material may consist
of, may consist
essentially of, or may be comprised of a bitumen froth, whole froth treatment
tailings, a fraction of
whole froth treatment tailings, and/or any other suitable material derived
from oil sands.
The methods of the invention are solvent extraction methods which are
performed
in one or more solvent extraction stages.
Exemplary embodiments of the invention are hereafter described with reference
to
Figure 1, in which a coarse mineral material fraction and a fine mineral
material fraction of froth
treatment tailings are both processed using the methods of the invention.
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In the exemplary embodiments depicted in Figure 1, the froth treatment
tailings
result from a process for recovering bitumen from oil sands. In the exemplary
embodiments, the
process for recovering bitumen from oil sands is comprised of producing a
bitumen froth from the
oil sands and is further comprised of separating the froth treatment tailings
from the bitumen froth
in a froth treatment process.
A typical bitumen froth may be comprised of about 60 percent bitumen, about 30
percent water and about 10 percent solid mineral material by weight. Bitumen
froth may therefore
be characterized generally as containing, in decreasing order of amount by
weight: (1) bitumen;
(2) water; and (3) solid mineral material.
Typical froth treatment tailings may be comprised of between about 3 percent
and
about 12 percent bitumen and froth treatment diluent (if the froth treatment
tailings contain a froth
treatment diluent), between about 15 percent and about 20 percent solid
mineral material, with the
balance being comprised primarily of water. Froth treatment tailings may
therefore be
characterized generally as containing, in decreasing order of amount by
weight: (1) water; (2)
solid mineral material; and (3) bitumen.
In the exemplary embodiments depicted in Figure 1, the froth treatment
tailings
may or may not contain a froth treatment diluent. For example, the froth
treatment tailings may
result from a froth treatment process in which no froth treatment diluent is
used, or the froth
treatment tailings may have been subjected to a tailings solvent recovery unit
(TSRU) process or a
similar process in which substantially all of the froth treatment diluent has
been recovered from
the froth treatment tailings.
Referring to Figure 1, a schematic process flow diagram depicting exemplary
embodiments of the methods of the invention is provided. In the exemplary
embodiments, froth
treatment tailings (20) resulting from a froth treatment process (not shown)
and comprising solid
mineral material, water and an amount of bitumen are first provided. The froth
treatment tailings
(20) also comprise an amount of a froth treatment diluent which is used in the
froth treatment
process.
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As depicted in Figure 1, the froth treatment tailings (20) are separated into
a coarse
mineral material fraction (22) and a fine mineral material fraction (24). As
depicted in Figure 1,
the froth treatment tailings (20) are separated using a hydrocyclone (26).
In some embodiments, the separation of the froth treatment tailings (20) may
be
performed so that the fine mineral material fraction (24) contains between
about 0.65 times and
about 0.85 times the amount of the bitumen which is contained in the froth
treatment tailings (20).
As depicted in Figure 1, the coarse mineral material fraction (22) and the
fine
mineral material fraction (24) are separately subjected to further processing
in accordance with the
exemplary embodiments of the methods of the invention.
The fine mineral material fraction (24) is comprised of solid mineral
material, water
and an amount of bitumen. The fine mineral material fraction (24) may also be
comprised of an
amount of froth treatment diluent from the froth treatment tailings (20).
As depicted in Figure 1, the fine mineral material fraction (24) is first
subjected to
conditioning (40) in order to produce a first solvent extraction feed material
(42) comprised of
solid mineral material, water, and an amount of bitumen. The first solvent
extraction feed material
(42) is also comprised of an amount of froth treatment diluent from the fine
mineral material
fraction (24).
A purpose of conditioning the fine mineral material fraction (24) is to
prepare the
fine mineral material fraction (24) for solvent extraction. As depicted in
Figure 1, conditioning
(40) the fine mineral material fraction (24) is comprised of agitating the
fine mineral material
fraction (24) in order to facilitate separation of the bitumen from the solid
mineral material.
As depicted in Figure 1, conditioning (40) the fine mineral material fraction
(24) is
further comprised of concentrating the fine mineral material fraction (24) so
that a concentration
of the bitumen by weight in the first solvent extraction feed material (42) is
greater than a
concentration of the bitumen by weight in the fine mineral material fraction
(24).
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In some embodiments, concentrating the fine mineral material fraction (24) may
be
performed so that the concentration of the bitumen by weight in the first
solvent extraction feed
material (42) is between about 1.25 times and about 3 times the concentration
of the bitumen by
weight in the fine mineral material fraction (24). In some particular
embodiments, concentrating
the fine mineral material fraction (24) may be performed so that the
concentration of the bitumen
by weight in the first solvent extraction feed material (42) is between about
2 times and about 3
times the concentration of the bitumen by weight in the fine mineral material
fraction (24).
As depicted in Figure 1, conditioning (40) the fine mineral material fraction
(24),
including both agitating the fine mineral material fraction (24) and
concentrating the fine mineral
material fraction (24) is performed by subjecting the fine mineral material
fraction (24) to froth
flotation in a froth flotation apparatus (44). As depicted in Figure 1, the
froth flotation apparatus
(44) is comprised of an agitator or mixer for agitating the fine mineral
material fraction (24) in the
froth flotation apparatus (44). Alternatively, the fine mineral material
fraction (24) may be passed
through a separate agitator or mixer before being subjected to froth flotation
in the froth flotation
apparatus (44).
Agitating the fine mineral material fraction (24) may be comprised of
subjecting
the fine mineral material fraction (24) to an agitation intensity, which may
be expressed in watts
per kilogram of fine mineral material fraction (24) which is agitated. In some
embodiments, the
agitation intensity may be at least about 25 watts per kilogram. In some
embodiments, the
agitation intensity may be between about 25 watts per kilogram and about 2000
watts per
kilogram. In some embodiments, the agitation intensity may be between about
200 watts per
kilogram and about 1500 watts per kilogram. In some embodiments, the agitation
intensity may
be between about 500 watts per kilogram and about 1200 watts per kilogram.
Agitating the fine mineral material fraction (24) may have an agitation
duration,
which may be expressed as the length of time for which the fine mineral
material fraction (24) is
agitated. In some embodiments, the agitation duration may be at least about 5
minutes. In some
embodiments, the agitation duration may be at between about 5 minutes and
about 40 minutes. In
some embodiments, the agitation duration may be between about 5 minutes and
about 30 minutes.
In some embodiments, the agitation duration may be between about 10 minutes
and about 20
minutes.
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The froth flotation may have a froth flotation intensity, which may be
expressed in
kilograms of added air per kilogram of fine mineral material fraction (24)
which is subjected to
froth flotation. In some embodiments, the froth flotation intensity may be at
least about 0.00005
kilograms of added air per kilogram of fine mineral material fraction (24). In
some embodiments,
the froth flotation intensity may be between about 0.00005 kilograms and about
0.05 kilograms of
added air per kilogram of fine mineral material fraction (24). In some
embodiments, the froth
flotation intensity may be between about 0.01 kilograms and about 0.03
kilograms of added air per
kilogram of fine mineral material fraction (24). In some embodiments, the
froth flotation intensity
may be between about 0.01 and about 0.02 kilograms of added air per kilogram
of fine mineral
material fraction (24).
The froth flotation may have a froth flotation duration, which may be
expressed as
the length of time for which the fine mineral material fraction (24) is
subjected to froth flotation.
In some embodiments, the froth flotation duration may be at least about 5
minutes. In some
embodiments, the froth flotation duration may be between about 5 minutes and
about 40 minutes.
In some embodiments, the froth flotation duration may be between about 5
minutes and about 30
minutes. In some embodiments, the froth flotation duration may be between
about 10 minutes and
about 20 minutes.
Conditioning the fine mineral material fraction (24) may be performed at any
suitable temperature. In some embodiments, conditioning the fine mineral
material fraction (24)
may be performed so that the fine mineral material fraction (24) has a
temperature of between
about 40 degrees Celsius and about 95 degrees Celsius.
Conditioning the fine mineral material fraction (24) in the froth flotation
apparatus
(44) produces the first solvent extraction feed material (42) as an overflow
product and produces
froth flotation tailings (46) as an underflow product. The froth flotation
tailings (46) may be
disposed of in any suitable manner.
In some embodiments, conditioning the fine mineral material fraction (24) may
be
performed so that the first solvent extraction feed material (42) contains
between about 0.6 times
and about 0.95 times the amount of the bitumen which is contained in the fine
mineral material
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fraction (24). In some particular embodiments in which conditioning the fine
mineral material
fraction (24) is comprised of subjecting the fine mineral material fraction
(24) to froth flotation,
the first solvent extraction feed material (42) may contain as much as about
0.95 times the amount
of the bitumen which his contained in the fine mineral material fraction (24).
The first solvent extraction feed material (42) is subjected to solvent
extraction (68)
in order to produce an extract (70) and a raffinate (72).
The solvent extraction (68) may be performed at any suitable temperature. In
some
embodiments, the solvent extraction (68) may be performed so that the solvent
extraction feed
material has a temperature of between about 40 degrees Celsius and about 95
degrees Celsius.
The solvent extraction (68) may be performed using a diluent as a solvent. The
diluent may be comprised of a hydrocarbon diluent which is introduced into the
solvent extraction
and/or the diluent may be comprised of residual froth treatment diluent which
is contained in the
froth treatment tailings (20) as a result of the froth treatment process.
As depicted in Figure 1, an amount of a hydrocarbon diluent is introduced to
the
solvent extraction (68). The hydrocarbon diluent may consist of, may consist
essentially of, or
may be comprised of any suitable naphthenic type diluent or any suitable
paraffinic type diluent.
The amount of the hydrocarbon diluent (108) which is introduced into the
solvent extraction (68)
may be expressed as an introduction rate of the hydrocarbon diluent (108).
In embodiments in which the hydrocarbon diluent is comprised of a paraffinic
type
diluent, the amount of the paraffinic type diluent is preferably selected so
that the precipitation of
asphaltenes is minimized and so that the recovery of bitumen is maximized.
In some particular embodiments in which the hydrocarbon diluent is comprised
of a
naphthenic type diluent, the hydrocarbon diluent may be comprised of or
consist of naphtha or
toluene. In some particular embodiments in which the hydrocarbon diluent is
comprised of or
consists of naphtha, the naphtha may have an aromaticity of between about 10
and 20 percent.
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The performance of toluene as the hydrocarbon diluent in the solvent
extraction
(68) and the performance of naphtha as the hydrocarbon diluent in the solvent
extraction (68) may
be dependent upon the diluent to feed material ratio by weight, upon the
diluent to bitumen ratio
by weight, upon the temperature at which the solvent extraction (68) is
performed, and upon the
length of time for which the solvent extraction (68) is performed.
At equivalent values of diluent to feed material ratio by weight and
equivalent
temperatures, the extent of recovery of bitumen in the solvent extraction (68)
may generally be
greater if the hydrocarbon diluent consists of toluene than if the hydrocarbon
diluent consists of
naphtha.
In embodiments in which the hydrocarbon diluent consists essentially of
toluene,
the extent of recovery of bitumen in the solvent extraction (68) may be
relatively insensitive to the
diluent to feed material ratio by weight.
In embodiments in which the hydrocarbon diluent consists essentially of
naphtha,
the extent of recovery of bitumen in the solvent extraction (68) may be
maximized if the diluent to
feed material ratio by weight is relatively low (i.e., less than or equal to
about 0.5).
In embodiments in which the hydrocarbon diluent consists essentially of
naphtha,
the water concentration in the extract (70) produced by the solvent extraction
(68) may decrease as
the temperature at which the solvent extraction (68) is performed increases if
the diluent to feed
material ratio by weight is relatively low (i.e., less than or equal to about
0.5).
In embodiments in which an amount of a froth treatment diluent is introduced
into
the solvent extraction (68), the hydrocarbon diluent is preferably selected
having regard to the
composition of the froth treatment diluent.
As a first consideration, in some applications it may be convenient for the
composition of the froth treatment diluent and the composition of the
hydrocarbon diluent to be
similar.
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However, as a second consideration, the use of a paraffinic type diluent as
the
hydrocarbon diluent where the solvent extraction feed material is comprised of
an amount of a
paraffinic type diluent as the froth treatment diluent may not be effective to
recover precipitated
asphaltenes, unless the concentration of the hydrocarbon diluent during the
solvent extraction (68)
can be maintained below the critical level which results in significant
asphaltene precipitation.
Stated otherwise, the use of a paraffinic type diluent as the hydrocarbon
diluent may be reasonably
effective for recovering non-asphaltenic bitumen material, but may be less
effective for recovering
asphaltenes.
As a result, where the solvent extraction feed material is comprised of an
amount of
a naphtha type diluent as the froth treatment diluent, the hydrocarbon diluent
may also be
comprised of a naphtha type diluent, since asphaltene precipitation is not a
major concern. Where
the solvent extraction feed material is comprised of an amount of a naphtha
type diluent as the
froth treatment diluent, the hydrocarbon diluent may be comprised of a
paraffinic type diluent if
recovery of asphaltenes is not essential or if the concentration of the
paraffinic type diluent can be
maintained below the critical level which results in significant asphaltene
precipitation. Where the
solvent extraction feed material is comprised of an amount of a paraffinic
type diluent as the froth
treatment diluent, the hydrocarbon diluent may be comprised of a naphtha type
diluent, since the
naphtha type diluent may facilitate the recovery of asphaltenes. Where the
solvent extraction feed
material is comprised of an amount of a paraffinic type diluent, the
hydrocarbon diluent may be
comprised of a paraffinic type diluent if recovery of asphaltenes is not
essential or if the
concentration of the paraffinic type diluent can be maintained below the
critical level which results
in significant asphaltene precipitation.
As depicted in Figure 1, the solvent extraction (68) is performed using two
stages
of solvent extraction and solvent extraction apparatus which are arranged in a
countercurrent
configuration.
As depicted in Figure 1, the first stage solvent extraction apparatus (80) is
comprised of a first mixer (82) and a first gravity settler (84) and the
second stage solvent
extraction apparatus (86) is comprised of a second mixer (88) and a second
gravity settler (90). As
depicted in Figure 1, each of the gravity settlers (84, 90) is comprised of a
gravity settling vessel.
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CA 02839509 2015-08-31
The first solvent extraction feed material (42) is delivered to the first
mixer (82) for
mixing and is then delivered to the first gravity settler (84). The first
solvent extraction feed
material (42) separates in the first gravity settler (84) into an overflow
zone (92) and an underflow
zone (94), with an interface therebetween. A first stage overflow product
(100) is withdrawn from
the overflow zone (92) and a first stage underflow product (102) is withdrawn
from the underflow
zone (94).
As depicted in Figure 1, a first intra-stage recycle component (112) is
withdrawn
from the overflow zone (92) of the first gravity settler (84) and is combined
with the first solvent
extraction feed material (42) in order to recycle the first intra-stage
recycle component (112) to the
first solvent extraction stage. In the embodiments depicted in Figure 1, a
first intra-stage recycle
ratio by weight of the first intra-stage recycle component (112) to the first
solvent extraction feed
material (42) may be between about 0.1 and about 1.5, or may be between about
0.5 and about 1.
The first stage underflow product (102) is delivered to the second mixer (88)
for
mixing and is then delivered to the second gravity settler (90) as a second
solvent extraction feed
material (103). The second solvent extraction feed material (103) separates in
the second gravity
settler (90) into an overflow zone (96) and an underflow zone (98), with an
interface therebetween.
A second stage overflow product (104) is withdrawn from the overflow zone (96)
and a second
stage underflow product (106) is withdrawn from the underflow zone (98).
As depicted in Figure 1, a second intra-stage recycle component (114) is
withdrawn
from the overflow zone (96) of the second gravity settler (90) and is combined
with the second
solvent extraction feed material (103) in order to recycle the second intra-
stage recycle component
(114) to the second solvent extraction stage. In the embodiments depicted in
Figure 1, a second
intra-stage recycle ratio by weight of the second intra-stage recycle
component (114) to the second
solvent extraction feed material (103) may be between about 0.1 and about 1.5,
or may be between
about 0.5 and about 1.
An amount of a hydrocarbon diluent (108) is also delivered to the second mixer
(88) for mixing with the first stage underflow product (102). The hydrocarbon
diluent (108) is
typically selected having regard to the composition of the froth treatment
diluent.
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CA 02839509 2014-01-15
The amount of the hydrocarbon diluent (108) which is delivered to the second
mixer (88) may be selected to provide a desired diluent to feed material ratio
by weight in the
second stage solvent extraction apparatus (86). Alternatively, the amount of
hydrocarbon diluent
(108) which is delivered to the second mixer (88) may be selected to provide a
desired diluent to
bitumen ratio by weight in the second stage solvent extraction apparatus (86).
In some particular embodiments, the desired diluent to feed material ratio by
weight
and/or the desired diluent to bitumen ratio by weight in the second stage
solvent extraction
apparatus (86) may be greater than the desired diluent to feed material ratio
by weight and/or the
desired diluent to bitumen ratio by weight in the first stage solvent
extraction apparatus (80).
The diluent to feed material ratio may be determined having regard to both the
composition and the amount of the froth treatment diluent which is included in
the solvent
extraction feed material.
In some embodiments in which the hydrocarbon diluent (108) and the froth
treatment diluent consist essentially of a naphthenic type diluent, the first
stage of solvent
extraction may be performed at a diluent to bitumen ratio of generally between
about 1 and about
10 by weight, and the second stage of solvent extraction may be performed at a
diluent to bitumen
ratio of generally between about 5 and about 100 by weight.
In some embodiments in which the hydrocarbon diluent (108) and the froth
treatment diluent consist essentially of a naphthenic type diluent, the first
stage of solvent
extraction may be performed at a diluent to feed material ratio of generally
between about 0.09
and about 1 by weight, and the second stage of solvent extraction may be
performed at a diluent to
feed material ratio of generally between about 0.1 and about 1 by weight.
In some embodiments in which the hydrocarbon diluent (108) and the froth
treatment diluent consist essentially of naphtha as a naphthenic type diluent,
the first stage of
solvent extraction may be performed at a diluent to feed material ratio of
between about 0.09 and
about 0.75 by weight, between about 0.09 and about 0.5 by weight, or between
about 0.09 and
about 0.25 by weight.
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In some embodiments in which the hydrocarbon diluent (108) and the froth
treatment diluent consist essentially of naphtha as a naphthenic type diluent,
the second stage of
solvent extraction may be performed at a diluent to feed material ratio of
between about 0.1 and
about 1 by weight, between about 0.1 and about 0.5 by weight, or between about
0.1 and about 0.3
by weight.
In some embodiments in which the hydrocarbon diluent (108) and the froth
treatment diluent consist essentially of toluene as a naphthenic type diluent,
the first stage of
solvent extraction may be performed at a diluent to feed material ratio of
between about 0.1 and
about 0.9 by weight, between about 0.1 and about 0.5 by weight, or between
about 0.2 and about
0.4 by weight.
In some embodiments in which the hydrocarbon diluent (108) and the froth
treatment diluent consist essentially of toluene as a naphthenic type diluent,
the second stage of
solvent extraction may be performed at a diluent to feed material ratio of
between about 0.1 and
about 1 by weight, between about 0.2 and about 0.5 by weight, or between about
0.2 and about 0.5
by weight.
Although naphtha and toluene are both naphthenic type diluents, the
performance
of naphtha in the solvent extraction (68) may be more sensitive to the diluent
to feed material ratio
than is the performance of toluene in the solvent extraction (68). In
particular, and as described
above, in some embodiments in which the hydrocarbon diluent (108) and the
froth treatment
diluent consist essentially of naphtha as a naphthenic type diluent, the
extent of recovery of
bitumen from the solvent extraction feed material may be maximized and the
solid mineral
material concentration in the extract (70) may be minimized by providing a
diluent to feed
material ratio which is relatively low (i.e. less than or equal to about 0.5).
In some embodiments in which the hydrocarbon diluent (108) and the froth
treatment diluent consist essentially of a paraffinic type diluent, the
solvent extraction (68) may be
performed under conditions in which the diluent to feed material ratio by
weight may be less than
a diluent to feed material ratio which will result in significant asphaltene
precipitation.
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The second stage overflow product (104) is recycled to the first mixer (82).
The
second stage underflow product (106) is the raffinate (72) and may be disposed
of in any suitable
manner. The first stage overflow product (100) is the extract (70).
The first stage overflow product (100) is withdrawn from the overflow zone
(92) at
a first stage overflow product withdrawal rate. The first stage underflow
product (102) is
withdrawn from the underflow zone (94) at a first stage underflow product
withdrawal rate. The
second stage overflow product (104) is withdrawn from the overflow zone (96)
at a second stage
overflow product withdrawal rate. The second stage underflow product (106) is
withdrawn from
the underflow zone (98) at a second stage underflow product withdrawal rate.
The first stage underflow product withdrawal rate is greater than the second
stage
underflow product withdrawal rate. As a result, a differential exists between
the first stage
underflow product withdrawal rate and the second stage underflow product
withdrawal rate. In
some embodiments as depicted in Figure 1, the differential between the first
stage underflow
product withdrawal rate and the second stage underflow product withdrawal rate
may be limited so
that the differential is no greater than the first stage overflow product
withdrawal rate. In some
embodiments as depicted in Figure 1, the differential between the first stage
underflow product
withdrawal rate and the second stage underflow product withdrawal rate may be
limited so that the
differential is no greater than the introduction rate of the hydrocarbon
diluent (108) into the
solvent extraction (68).
The raffinate (72) may be subjected to a solvent recovery process before
disposal in
order to recover substantially all or a portion of the froth treatment diluent
and the hydrocarbon
diluent (108) therefrom.
The extract (70) is comprised of solid mineral material, water, and an amount
of
bitumen. The extract (72) is also comprised of an amount of the froth
treatment diluent from the
second feed material (60) and an amount of the hydrocarbon diluent (108) which
is present in the
extract (70) as a result of the recycling of the second stage extraction
overflow product (104) to
the first mixer (82).
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In some embodiments, the extract (70) may contain between about 0.7 times and
about 0.95 times the amount of the bitumen which is contained in the first
solvent extraction feed
material (42). In some embodiments the extract (70) may contain between about
0.6 times and
about 0.8 times the amount of the bitumen which is contained in the fine
mineral material fraction
(24).
The extract (70) has a solid mineral material concentration by weight and a
water
concentration by weight. If the solid mineral material concentration and the
water concentration in
the extract (70) are below acceptable limits, the extract (70) may be suitable
for further processing
and/or transport as a diluted bitumen (i.e., dilbit) product. The further
processing of the extract
(70) may be comprised of subjecting the extract (70) to a diluent recovery
process (not shown) for
recovering substantially all or a portion of the froth treatment diluent and
the hydrocarbon diluent
(108) therefrom.
If, however, the solid mineral material concentration and/or the water
concentration
by weight in the extract (70) are above acceptable limits, the extract (70)
may optionally be
subjected to clarifying (not shown) in order to produce a clarified extract
which has a reduced solid
mineral material concentration by weight and/or water concentration by weight
in comparison with
the extract (70).
The froth flotation tailings (46) and the raffinate (72) may similarly be
subjected to
a diluent recovery process (not shown) in order to recover substantially all
or a portion of the froth
treatment diluent and the hydrocarbon diluent (108) therefrom.
The coarse solid material fraction (22) is comprised of solid mineral
material,
water, and an amount of bitumen. A large proportion of the heavy minerals
which are originally
contained in the froth treatment tailings (20) will typically be present as
coarse solid mineral
material in the coarse solid material fraction (22).
The coarse solid material fraction (22) may also be comprised of an amount of
froth
treatment diluent from the froth treatment tailings (20).
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CA 02839509 2014-01-15
Where the coarse solid material fraction (22) is comprised of a froth
treatment
diluent, the froth treatment diluent may be comprised of a naphthenic type
diluent and/or a
paraffinic type diluent, depending upon the type of froth treatment process
from which the froth
treatment tailings (20) were obtained.
Although the froth treatment tailings (20) may be obtained from a paraffinic
froth
treatment process so that the coarse solid material fraction (22) may be
comprised of a paraffinic
type diluent as a froth treatment diluent, the processing of the coarse solid
material fraction (22)
may be more effective if the froth treatment tailings (20) have been produced
by a naphthenic
froth treatment process than if the froth treatment tailings (20) have been
produced by a paraffinic
froth treatment process.
A reason for this is that froth treatment tailings (20) from a paraffinic
froth
treatment process may typically contain relatively larger amounts of bitumen
than froth treatment
tailings (20) from a naphthenic froth treatment process. In addition, the
bitumen contained in froth
treatment tailings (20) from a paraffinic froth treatment process typically
includes a relatively
large proportion of asphaltenes.
The amount and nature of the bitumen which is typically contained in froth
treatment tailings (20) from a paraffinic froth treatment process presents
processing challenges
which may require more aggressive and/or rigorous process conditions for
processing the coarse
mineral material fraction (22) than if the froth treatment tailings (22) have
been produced from a
naphthenic froth treatment process.
As depicted in Figure 1, the coarse mineral material fraction (22) is first
subjected
to froth flotation (140) in order to produce a first solvent extraction feed
material (142) and froth
flotation tailings (144) therefrom.
As depicted in Figure 1, the froth flotation (140) is comprised of a first
froth
flotation stage (146) and a second froth flotation stage (148). As depicted in
Figure 1, the first
froth flotation stage (146) is performed in a first flotation vessel (150) and
the second froth
flotation stage (148) is performed in a second flotation vessel (152).
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CA 02839509 2014-01-15
As depicted in Figure 1, both the first froth flotation stage (146) and the
second
froth flotation stage (148) are performed in the presence of a suitable amount
of an injected gas
such as air (not shown) and in the presence of a suitable amount of a suitable
frothing agent (not
shown). Non-limiting examples of potentially suitable frothing agents include
glycol based
frothers and/or alcohol based frothers.
The concentration of the frothing agent in the coarse solid material fraction
(22)
may be any concentration which his suitable for encouraging the formation of a
froth layer. In
some embodiments, the concentration of the frothing agent may be less than or
equal to about 200
grams of frothing agent per tonne of solid mineral material which is included
in the coarse solid
material fraction (22). In some embodiments, the concentration of the frothing
agent may be less
than or equal to about 100 grams per tonne of solid mineral material which is
included in the
coarse solid material fraction (22). In some embodiments, the concentration of
the frothing agent
may be between about 15 grams and about 50 grams per tonne of solid mineral
material which is
included in the coarse solid material fraction (22).
As a specific non-limiting example, in the embodiments depicted in Figure 1, a
suitable frothing agent may be CytecTM F-507 frother, a product of Cytec
Industries Inc., and may
be added to the feed material to provide a frothing agent concentration of
between about 15 grams
and about 50 grams per tonne of feed material in each of the froth flotation
stages (146,148).
The froth flotation stages (146,148) may be arranged in a scavenging
configuration
or in a cleaning configuration. The scavenging configuration of the froth
flotation (140) is
depicted by solid lines in Figure 1. The cleaning configuration of the froth
flotation (140) is
depicted by dashed lines in Figure 1.
In the scavenging configuration of the froth flotation (140), the first froth
flotation
stage (146) is a rougher froth flotation stage and the second froth flotation
stage (148) is a
scavenger froth flotation stage so that subjecting the coarse mineral material
fraction (22) to froth
flotation (140) is comprised of subjecting the coarse mineral material
fraction (22) to the rougher
froth flotation stage in order to produce a rougher stage float product (154)
and a rougher stage
sink product (156), and is further comprised of subjecting the rougher stage
sink product (156) to
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CA 02839509 2014-01-15
the scavenger froth flotation stage in order to produce a scavenger stage
float product (158) and a
scavenger stage sink product (160).
In the scavenging configuration of the froth flotation (140) as depicted in
Figure 1,
the rougher stage float product (154) and the scavenger stage float product
(158) are combined so
that the first solvent extraction feed material (142) is comprised of or
consists essentially of the
rougher stage float product (154) and the scavenger stage float product (158),
and the froth
flotation tailings (144) are comprised of or consist essentially of the
scavenger stage sink product
(160).
In the scavenging configuration of the froth flotation (140), subjecting the
rougher
stage sink product (156) to the scavenger froth flotation stage may be
comprised of adding an
amount of a collector (not shown) to the rougher stage sink product (156) in
order to enhance the
recovery of heavy minerals in the scavenger stage float product (158). In the
embodiments
depicted in Figure 1, the collector may be comprised of a hydrocarbon liquid
such as kerosene,
naphtha or a mixture thereof. It is believed that the collector adheres to
heavy minerals which
have amounts of bitumen attached thereto, thereby increasing the
hydrophobicity and floatability
of the heavy minerals.
The concentration of the collector in the rougher stage sink product (156) may
be
any concentration which is suitable for collecting the heavy minerals which
are contained in the
rougher stage sink product (156) without interfering significantly with the
production of the froth
layer in the scavenger froth flotation stage. In some embodiments, the
concentration of the
collector in the rougher stage sink product (156) may be less than or equal to
about 10 liters per
tonne of solid mineral material which is included in the rougher stage sink
product (156). In some
embodiments, the concentration of the collector in the rougher stage sink
product (156) may be
less than or equal to about 1 liter per tonne of solid mineral material which
is included in the
rougher stage sink product (156).
In the scavenging configuration of the froth flotation (140) as depicted in
Figure 1,
the rougher froth flotation stage and the scavenger froth flotation stage are
performed so that the
residence time of the coarse mineral material fraction in the rougher froth
flotation stage is longer
than the residence time of the rougher stage sink product in the scavenger
froth flotation stage.
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CA 02839509 2014-01-15
For example, in some applications of the method of the invention, the
residence time of the coarse
mineral material fraction in the rougher froth flotation stage may be about 10
minutes and the
residence time of the rougher stage sink product in the scavenger froth
flotation stage may be
about 5 minutes.
In the cleaning configuration of the froth flotation (140), the first froth
flotation
stage (146) is a rougher froth flotation stage and the second froth flotation
stage (148) is a cleaner
froth flotation stage so that subjecting the coarse mineral material fraction
(22) to froth flotation
(140) is comprised of subjecting the coarse mineral material fraction (22) to
the rougher froth
flotation stage in order to produce a rougher stage float product (154a) and a
rougher stage sink
product (156a), and is further comprised of subjecting the rougher stage float
product (154a) to the
cleaner froth flotation stage in order to produce a cleaner stage float
product (158a) and a cleaner
stage sink product (160a).
In the cleaning configuration of the froth flotation (140) as depicted in
Figure 1, the
first solvent extraction feed material (142) is comprised of or consists
essentially of the cleaner
stage float product (158a). Furthermore, in the cleaning configuration of the
froth flotation (140)
as depicted in Figure 1, the rougher stage sink product (156a) and the cleaner
stage sink product
(160a) are combined so that the froth flotation tailings (144) are comprised
of or consist
essentially of the rougher stage sink product (156a) and the cleaner stage
sink product (160a).
In the embodiments of both the scavenging configuration and the cleaning
configuration of the froth flotation (140) as described above, the coarse
mineral material fraction
(22) may have a solid mineral material concentration of between about 20
percent and about 80
percent by weight of the coarse mineral material fraction (22) when the coarse
mineral material
fraction (22) is introduced to the froth flotation (140) or more particularly,
when the coarse
mineral material fraction (22) is introduced to the first froth flotation
stage (146).
A purpose of the froth flotation (140) is to concentrate the heavy minerals by
rejecting the froth flotation tailings (144) in order to produce the first
solvent extraction feed
material (142). The first solvent extraction feed material (142) has a
substantially smaller volume
than the coarse mineral material fraction (22) and can therefore be processed
more efficiently than
the coarse mineral material fraction (22).
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Following the froth flotation (140), the first solvent extraction feed
material (142)
is subjected to solvent extraction (170) in order to produce therefrom a
raffinate (172) comprising
a heavy mineral concentrate with reduced bitumen content and an extract (174)
containing
bitumen.
The first solvent extraction feed material (142) has a solid mineral material
concentration. The first solvent extraction feed material (142) may have any
solid mineral
material concentration which is suitable for conducting the solvent extraction
(170). In some
embodiments, the first solvent extraction feed material (142) may have a solid
mineral material
concentration which is lower than a solid mineral material concentration which
will interfere with
the recovery of the extract (174). In some embodiments, the first solvent
extraction feed material
(142) may have a solid mineral material concentration of at least about 20
percent by weight of the
first solvent extraction feed material (142) when it is introduced to the
solvent extraction (170). In
some embodiments, the first solvent extraction feed material (142) may have a
solid mineral
material concentration of less than or equal to about 80 percent by weight of
the first solvent
extraction feed material (142) when it is introduced to the solvent extraction
(170). In some
embodiments, the first solvent extraction feed material (142) may have a solid
mineral material
concentration of less than or equal to about 70 percent by weight of the first
solvent extraction
feed material (142) when it is introduced to the solvent extraction (170). In
some embodiments,
the first solvent extraction feed material (142) may have a solid mineral
material concentration of
between about 20 percent and 70 percent by weight of the first solvent
extraction feed material
(142) when it is introduced to the solvent extraction (170).
The bitumen content of the solvent extraction feed material will typically
decrease
as the number of stages of solvent extraction (170) increases, so that the
solvent extraction feed
material is progressively cleaned of bitumen by the stages of solvent
extraction. In some
embodiments, the number of stages of solvent extraction (170) may be selected
so that the bitumen
concentration of the raffinate (172) is no greater than a desired limit which
will facilitate
subsequent processing of the raffinate (172) to recover the heavy minerals
therefrom.
In some embodiments, the desired limit of the bitumen concentration in the
raffinate (172) may be about 0.5 percent bitumen by weight of the raffinate
(172).
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CA 02839509 2015-08-31
As depicted in Figure 1, the solvent extraction (170) is comprised of a first
solvent
extraction stage (176), a second solvent extraction stage (178) and a third
solvent extraction stage
(180).
As depicted in Figure 1, the solvent extraction stages (176,178,180) are
arranged in
a countercurrent configuration. As a result, the extract (174) is produced
from the first solvent
extraction stage (176) and the raffinate (172) is produced from the third
solvent extraction stage
(180).
The first solvent extraction stage (176) is comprised of attritioning the
first solvent
extraction feed material (142) in order to produce an attritioned first
solvent extraction feed
material (192). The first solvent extraction stage (176) is further comprised
of separating the
attritioned first solvent extraction feed material (192) in order to produce a
first stage underflow
product (194) and a first stage overflow product (196).
As depicted in Figure 1, the first solvent extraction feed material (142) may
have a
solid mineral material concentration of between about 20 percent and about 70
percent by weight
of the first solvent extraction feed material (142). The first solvent
extraction feed material (142)
may be comprised of an amount of make-up water (197) to provide a desired
solid mineral material
concentration for the first solvent extraction feed material (142). The make-
up water (197) may be
comprised of or may consist essentially of fresh water and/or water which is
recycled from the
methods of the invention or from other processes.
As depicted in Figure 1, the attritioning of the first solvent extraction feed
material
(142) is performed by mixing the first solvent extraction feed material (142)
in a first mixer (198).
A purpose of the attritioning is to liberate bitumen from the first solvent
extraction feed material
(142) so that the bitumen can more effectively be separated from the heavy
minerals in the
separating of the attritioned first solvent extraction feed material (192).
Another purpose of the
attritioning is to mix the constituents of the first solvent extraction feed
material (142).
As depicted in Figure 1, the separating of the attritioned first solvent
extraction feed
material (192) is performed by passing the attritioned first solvent
extraction feed material (192)
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CA 02839509 2014-01-15
through a first gravity settler (200). As depicted in Figure 1, the first
gravity settler (200) is
comprised of a first gravity settling vessel.
The attritioned first solvent extraction feed material (192) separates in the
first
gravity settler (200) into an overflow zone (202) and an underflow zone (204),
with an interface
therebetween. The first stage overflow product (196) is withdrawn from the
overflow zone (202)
and the first stage underflow product (194) is withdrawn from the underflow
zone (204).
As depicted in Figure 1, a first intra-stage recycle component (206) is
withdrawn
from the overflow zone (202) of the first gravity settler (200) and is
combined with the first
solvent extraction feed material (142) in order to recycle the first intra-
stage recycle component
(206) to the first solvent extraction stage. In the embodiments depicted in
Figure 1, a first intra-
stage recycle ratio by weight of the first intra-stage recycle component (206)
to the attritioned first
solvent extraction feed material (192) may be between about 0.1 and 1.5, or
may be between about
0.5 and about 1.
As depicted in Figure 1, the extract (174) is comprised of or consists
essentially of
the first stage overflow product (196). As depicted in Figure 1, the first
stage underflow product
(194) is subjected to the second solvent extraction stage (178) as a second
solvent extraction feed
material (210).
The second solvent extraction feed material (210) has a solid mineral material
concentration. The second solvent extraction feed material (210) may have any
solid mineral
material concentration which is suitable for conducting the solvent extraction
(170). In some
embodiments, the second solvent extraction feed material (210) may have a
solid mineral material
concentration which is lower than a solid mineral material concentration which
will interfere with
the recovery of the extract (174). In some embodiments, the second solvent
extraction feed
material (210) may have a solid mineral material concentration of at least
about 20 percent by
weight of the second solvent extraction feed material (210) when it is
introduced to the solvent
extraction (170). In some embodiments, the second solvent extraction feed
material (210) may
have a solid mineral material concentration of less than or equal to about 80
percent by weight of
the second solvent extraction feed material (210) when it is introduced to the
solvent extraction
(170). In some embodiments, the second solvent extraction feed material (210)
may have a solid
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CA 02839509 2014-01-15
mineral material concentration of less than or equal to about 70 percent by
weight of the second
solvent extraction feed material (210) when it is introduced to the solvent
extraction (170). In
some embodiments, the second solvent extraction feed material (210) may have a
solid mineral
material concentration of between about 20 percent and 70 percent by weight of
the second solvent
extraction feed material (210) when it is introduced to the solvent extraction
(170).
The second solvent extraction stage (178) is comprised of attritioning the
second
solvent extraction feed material (210) in order to produce an attritioned
second solvent extraction
feed material (212). The second solvent extraction stage (178) is further
comprised of separating
the attritioned second solvent extraction feed material (212) in order to
produce a second stage
underflow product (214) and a second stage overflow product (216).
As depicted in Figure 1, the second solvent extraction feed material (210) may
have
a solid mineral material concentration of between about 20 percent and about
70 percent by weight
of the second solvent extraction feed material (210).
As depicted in Figure 1, the attritioning of the second solvent extraction
feed
material (210) is performed by mixing the second solvent extraction feed
material (210) in a
second mixer (218). A purpose of the attritioning is to liberate bitumen from
the second solvent
extraction feed material (210) so that the bitumen can more effectively be
separated from the
heavy minerals in the separating of the attritioned second solvent extraction
feed material (212).
Another purpose of the attritioning is to mix the constituents of the second
solvent extraction feed
material (210).
As depicted in Figure 1, the separating of the attritioned second solvent
extraction
feed material (212) is performed by passing the attritioned second solvent
extraction feed material
(212) through a second gravity settler (220). As depicted in Figure 1, the
second gravity settler
(220) is comprised of a second gravity settling vessel.
The attritioned second solvent extraction feed material (212) separates in the
second gravity settler (220) into an overflow zone (222) and an underflow zone
(224), with an
interface therebetween. The second stage overflow product (216) is withdrawn
from the overflow
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CA 02839509 2014-01-15
zone (222) and the second stage underflow product (214) is withdrawn from the
underflow zone
(224).
As depicted in Figure 1, a second intra-stage recycle component (226) is
withdrawn
from the overflow zone (222) of the second gravity settler (220) and is
combined with the second
solvent extraction feed material (210) in order to recycle the second intra-
stage recycle component
(226) to the second solvent extraction stage. In the embodiments depicted in
Figure 1, a second
intra-stage recycle ratio by weight of the second intra-stage recycle
component (226) to the
attritioned second solvent extraction feed material (212) may be between about
0.1 and 1.5, or
may be between about 0.5 and about 1.
As depicted in Figure 1, the second stage overflow product (216) is mixed with
the
first solvent extraction feed material (142) in the first mixer (198) so that
the second stage
overflow product (216) is introduced into the first solvent extraction stage
(176). As depicted in
Figure 1, the second solvent extraction underflow component (214) is subjected
to the third
solvent extraction stage (180) as a third solvent extraction feed material
(230).
The third solvent extraction feed material (230) has a solid mineral material
concentration. The third solvent extraction feed material (230) may have any
solid mineral
material concentration which is suitable for conducting the solvent extraction
(170). In some
embodiments, the third solvent extraction feed material (230) may have a solid
mineral material
concentration which is lower than a solid mineral material concentration which
will interfere with
the recovery of the extract (174). In some embodiments, the third solvent
extraction feed material
(230) may have a solid mineral material concentration of at least about 20
percent by weight of the
third solvent extraction feed material (230) when it is introduced to the
solvent extraction (170).
In some embodiments, the third solvent extraction feed material (230) may have
a solid mineral
material concentration of less than or equal to about 80 percent by weight of
the third solvent
extraction feed material (230) when it is introduced to the solvent extraction
(170). In some
embodiments, the third solvent extraction feed material (230) may have a solid
mineral material
concentration of less than or equal to about 70 percent by weight of the third
solvent extraction
feed material (230) when it is introduced to the solvent extraction (170). In
some embodiments,
the third solvent extraction feed material (230) may have a solid mineral
material concentration of
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CA 02839509 2014-01-15
between about 20 percent and 70 percent by weight of the third solvent
extraction feed material
(230) when it is introduced to the solvent extraction (170).
The third solvent extraction stage (180) is comprised of attritioning the
third
solvent extraction feed material (230) in order to produce an attritioned
third solvent extraction
feed material (232). The third solvent extraction stage (180) is further
comprised of separating the
attritioned third solvent extraction feed material (232) in order to produce a
third stage underflow
product (234) and a third stage overflow product (236).
As depicted in Figure 1, the third solvent extraction feed material (230) may
have a
solid mineral material concentration of between about 20 percent and about 70
percent by weight
of the third solvent extraction feed material (230).
As depicted in Figure 1, the attritioning of the third solvent extraction feed
material
(230) is performed by mixing the third solvent extraction feed material (230)
in a third mixer
(238). A purpose of the attritioning is to liberate bitumen from the third
solvent extraction feed
material (230) so that the bitumen can more effectively be separated from the
heavy minerals in
the separating of the attritioned third solvent extraction feed material
(232). Another purpose of
the attritioning is to mix the constituents of the third solvent extraction
feed material (230).
As depicted in Figure 1, the separating of the attritioned third solvent
extraction
feed material (232) is performed by passing the attritioned third solvent
extraction feed material
(232) through a third gravity settler (240). As depicted in Figure 1, the
third gravity settler (240)
is comprised of a third gravity settling vessel.
The attritioned third solvent extraction feed material (232) separates in the
third
gravity settler (240) into an overflow zone (248) and an underflow zone (250),
with an interface
therebetween. The third stage overflow product (236) is withdrawn from the
overflow zone (248)
and the third stage underflow product (234) is withdrawn from the underflow
zone (250).
As depicted in Figure 1, a third intra-stage recycle component (252) is
withdrawn
from the overflow zone (248) of the third gravity settler (240) and is
combined with the third
solvent extraction feed material (230) in order to recycle the third intra-
stage recycle component
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CA 02839509 2014-01-15
(252) to the third solvent extraction stage. In the embodiments depicted in
Figure 1, a third intra-
stage recycle ratio by weight of the third intra-stage recycle component (252)
to the attritioned
third solvent extraction feed material (232) may be between about 0.1 and 1.5,
or may be between
about 0.5 and about 1.
As depicted in Figure 1, the third stage overflow product (236) is mixed with
the
first stage underflow product (194) in the second mixer (218) so that the
third stage overflow
product (236) is introduced into the second solvent extraction stage (178). As
depicted in Figure
1, the raffinate (172) is comprised of or consists essentially of the third
stage underflow product
(234).
The solvent extraction (170) may be performed using a diluent as a solvent.
The
diluent may be comprised of a hydrocarbon diluent which is introduced into the
solvent extraction
(170) and/or the diluent may be comprised of residual froth treatment diluent
which is contained in
the froth treatment tailings (20) as a result of the froth treatment process.
The diluent may be comprised of or may consist essentially of one or more
suitable
naphthenic type diluents or may be comprised of a mixture of one or more
suitable naphthenic
type diluents and/or paraffinic type diluents. The amount of the diluent may
be any amount which
is effective to facilitate the separation of the solvent extraction feed
material in order to produce
the raffinate (172) and the extract (174).
In some embodiments in which the diluent may be comprised of a paraffinic type
diluent, the paraffinic type diluent may be present in the diluent as a
residual amount of a froth
treatment diluent which was contained in the froth treatment tailings (20) as
a result of a paraffinic
froth treatment process. In some embodiments in which the diluent may consist
essentially of one
or more naphthenic type diluents, some of the naphthenic type diluent may be
present in the
diluent as a residual amount of a froth treatment diluent which was contained
in the froth treatment
tailings (20) as a result of a naphthenic froth treatment process.
In some embodiments in which the diluent may be comprised of a paraffinic type
diluent, the amount of the paraffinic type diluent may be selected in order to
control the amount of
asphaltenes which are precipitated during the solvent extraction (170), since
precipitated
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asphaltenes will tend to be included in the raffinate (172) and not in the
extract (174). An
excessive amount of precipitated asphaltenes contained in the raffinate (172)
may interfere with
subsequent processing to recover the heavy minerals from the raffinate (172).
In some embodiments in which the diluent may be comprised of a naphthenic type
diluent, a suitable diluent may be comprised of or may consist essentially of
naphtha or toluene.
In some embodiments, the diluent may be comprised of or may consist
essentially of naphtha.
The amount of the diluent may be any amount which is suitable for conducting
the
solvent extraction (170). In some embodiments in which the diluent may be
comprised of a
naphthenic type diluent, the amount of the diluent may be selected in order to
maximize the
separation of the solvent extraction feed material into the raffinate (172)
and the extract (174).
As depicted in Figure 1, an amount of a hydrocarbon diluent (244) is combined
with the second stage underflow product (214) so that the hydrocarbon diluent
(244) is introduced
into the third solvent extraction stage (180). As depicted in Figure 1, the
hydrocarbon diluent
(244) consists essentially of naphtha. The amount of the hydrocarbon diluent
(244) which is
introduced into the solvent extraction (170) may be expressed as an
introduction rate of the
hydrocarbon diluent (244).
As depicted in Figure 1, the amount of the hydrocarbon diluent (244) is
selected so
that each of the first solvent extraction stage (176), the second solvent
extraction stage (178), and
the third solvent extraction stage (180) is performed in the presence of at
least about 15 percent by
weight of a diluent.
The first stage overflow product (196) is withdrawn from the overflow zone
(202)
at a first stage overflow product withdrawal rate. The first stage underflow
product (194) is
withdrawn from the underflow zone (204) at a first stage underflow product
withdrawal rate. The
second stage overflow product (216) is withdrawn from the overflow zone (222)
at a second stage
overflow product withdrawal rate. The second stage underflow product (214) is
withdrawn from
the underflow zone (224) at a second stage underflow product withdrawal rate.
The third stage
overflow product (236) is withdrawn from the overflow zone (248) at a third
stage overflow
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CA 02839509 2014-01-15
product withdrawal rate. The third stage underflow product (234) is withdrawn
from the
underflow zone (250) at a third stage underflow product withdrawal rate.
At least one of the first stage underflow product withdrawal rate and the
second
stage underflow product withdrawal rate is greater than the third stage
underflow product
withdrawal rate. As a result, a differential exists between the first stage
underflow product
withdrawal rate and/or the second stage underflow product withdrawal rate in
comparison with the
third stage underflow product withdrawal rate. In some embodiments as depicted
in Figure 1, the
differential between the first stage underflow product withdrawal rate and/or
the second stage
underflow product withdrawal rate in comparison with the third stage underflow
product
withdrawal rate may be limited so that the differential is no greater than the
first stage overflow
product withdrawal rate. In some embodiments as depicted in Figure 1, the
differential between
the first stage underflow product withdrawal rate and/or the second stage
underflow product
withdrawal rate in comparison with the third stage underflow product
withdrawal rate may be
limited so that the differential is no greater than the introduction rate of
the hydrocarbon diluent
(244) into the solvent extraction (170).
In some embodiments, the processing of the coarse mineral material fraction
(22)
may be capable of producing a raffinate (172) which has a bitumen
concentration which is no
greater than about 0.5 percent by weight of the raffinate (172). In some
embodiments, the
processing of the coarse mineral material fraction (22) may be capable of
producing a raffinate
(172) which has a bitumen concentration which is no greater than about 0.5
percent of the dry
weight of the raffinate (172), where the dry weight of the raffinate (172) is
the weight of the
raffinate (172) excluding water.
In some embodiments, the processing of the coarse mineral material fraction
(22)
may be capable of producing an extract (174) which has a water concentration
which is no greater
than about 0.5 percent by weight of the extract (174). In some embodiments,
the processing of the
coarse mineral material fraction (22) may be capable of producing an extract
(174) which has a
solid mineral material concentration which is no greater than about 0.5
percent by weight of the
extract (174). In some embodiments, the processing of the coarse mineral
material fraction (22)
may be capable of producing an extract (174) which has a combined solid
mineral material and
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CA 02839509 2014-01-15
water concentration which is no greater than about 1.0 percent by weight of
the extract (174), or in
some embodiments no greater than about 0.5 percent by weight of the extract
(174).
In some embodiments, the processing of the coarse mineral material fraction
(22)
may be capable of recovering in the first solvent extraction feed material
(142) at least about 90
percent of the heavy minerals which are contained in the coarse mineral
material fraction (22) by
weight of the coarse mineral material fraction (22). In some embodiments, the
processing of the
coarse mineral material fraction (22) may be capable of recovering in the
first solvent extraction
feed material (142) at least about 95 percent of the heavy minerals which are
contained in the
coarse mineral material fraction (22) by weight of the coarse mineral material
fraction (22). In
some embodiments, the processing of the coarse mineral material fraction (22)
may be capable of
recovering in the first solvent extraction feed material (142) at least about
80 percent of the
bitumen which is contained in the coarse mineral material fraction (22) by
weight of the coarse
mineral material fraction (22).
In some embodiments, the processing of the coarse mineral material fraction
(22)
may be capable of recovering in the extract (174) at least about 80 percent of
the bitumen which is
contained in the coarse mineral material fraction (22) by weight of the coarse
mineral material
fraction (22). In some embodiments, the processing of the coarse mineral
material fraction (22)
may be capable of recovering in the extract (174) at least about 85 percent of
the bitumen which is
contained in the coarse mineral material fraction (22) by weight of the coarse
mineral material
fraction (22). In some embodiments, the processing of the coarse mineral
material fraction (22)
may be capable of recovering at least about 90 percent of the bitumen which is
contained in the
coarse mineral material fraction (22) by weight of the coarse mineral material
fraction (22).
Following the solvent extraction (170), the extract (174) may be further
processed
and/or may be stored or transported for further processing. It may also be
desirable to subject the
extract (174) to a diluent recovery process (not shown) in order to recover at
least a portion of the
diluent from the extract (174) in order to facilitate recycling of the diluent
before processing,
storing and/or transporting the extract (174).
In some embodiments, all or a portion of the extract (174) may be provided to
the
solvent extraction (68) relating to the fine mineral material fraction (24) to
provide or to
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CA 02839509 2014-01-15
supplement the hydrocarbon diluent (108) which is added in the solvent
extraction (68). Providing
all or a portion of the extract (174) to the solvent extraction (68) may
reduce the amount of fresh
hydrocarbon diluent (108) which must be added in the solvent extraction (68).
Following the solvent extraction (170), the raffinate (172) may be further
processed
to recover the heavy minerals which are contained therein. It may also be
desirable to subject the
raffinate (172) to a diluent recovery process (not shown) in order to reduce
the diluent
concentration of the raffinate (172) before attempting to recover the heavy
minerals therefrom.
Referring to Figure 2, a material balance for a pilot plant scale experiment
is
provided for a method for processing a fine mineral material fraction (24) of
froth treatment
tailings (20) in accordance with the methods of the invention. Referring to
Figure 3, a material
balance for a pilot plant scale experiment is provided for a method for
processing a coarse mineral
material fraction (22) of froth treatment tailings (20) in accordance with
methods of the invention.
Referring to Figure 2, the first stage underflow product withdrawal rate is
3.10
kilograms per minute, the second stage underflow product withdrawal rate is
2.90 kilograms per
minute, the first overflow product withdrawal rate is 0.34 kilograms per
minute, and the
introduction rate of the hydrocarbon diluent (108) is 0.32 kilograms per
minute. It is noted that
the differential between the first stage underflow product withdrawal rate and
the second stage
underflow product withdrawal rate is 0.20 kilograms per minute. The
differential is therefore less
than both the first overflow product withdrawal rate and the introduction rate
of the hydrocarbon
diluent (108).
Referring to Figure 3, the first stage underflow product withdrawal rate is
0.44
kilograms per minute, the second stage underflow product withdrawal rate is
0.35 kilograms per
minute, the third stage underflow product withdrawal rate is 0.35 kilograms
per minute, the first
overflow product withdrawal rate is 0.045 kilograms per minute, and the
introduction rate of the
hydrocarbon diluent (244) is 0.06 kilograms per minute. It is noted that the
differential between
the first stage underflow product withdrawal rate and the third stage
underflow product withdrawal
rate is 0.09 kilograms per minute. The differential is therefore greater than
both the first overflow
product withdrawal rate and the introduction rate of the hydrocarbon diluent
(244).
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CA 02839509 2014-01-15
As described herein, the present invention is directed at solvent extraction
separation methods. In some embodiments, the present invention is more
particularly directed at
withdrawing an intra-stage recycle component from one or more solvent
extraction stages. In
some embodiments, the present invention is more particularly directed at
providing that an
underflow product withdrawal rate in at least one of the solvent extraction
stages other than the
final solvent extraction stage is greater than the underflow product
withdrawal rate in the final
solvent extraction stage so that there is a differential between the underflow
product withdrawal
rates.
Both of these aspects of the invention are directed toward improving
multiphase
separation processes which can be complicated by interphase developments such
as emulsions, rag
layers, sludges, etc. and at improving the separation of the bitumen phase in
the solvent extraction
stages.
1 5
Both of these aspects of the invention may potentially provide improved
process
efficiencies in that relatively less hydrocarbon diluent may potentially be
necessary in the
processes and/or the size of the processes may potentially be reduced, by
ultimately reducing the
amount of hydrocarbon diluent which is required to achieve a desired standard
of performance.
In the intra-stage recycle aspect of the invention, providing an intra-stage
recycle
component creates an opportunity to remove interphase developments such as rag
material from
the solvent extraction apparatus and transferring such material to a mixer
where it may be treated
with mechanical energy and potentially be shifted to a new equilibrium that
may be less prone to
developing such interphase developments. Providing an intra-stage recycle
component may also
provide a further benefit of reducing the solid mineral material concentration
in the solvent
extraction apparatus, thereby reducing the viscosity of the bitumen phase in
the solvent extraction
apparatus and potentially improving the separation in the solvent extraction
apparatus and
potentially improving the quality of the extract produced by the solvent
extraction.
In the underflow component withdrawal rate differential aspect of the
invention, the
relatively higher underflow component withdrawal rate in an upstream solvent
extraction stage
causes a reduction in the residence time, primarily of the underflow component
in the solvent
extraction apparatus, which may potentially "draw" some interphase
developments such as rag
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CA 02839509 2014-01-15
material to the underflow component, thereby potentially reducing an
accumulation of rag material
in the solvent extraction apparatus.
In the practice of the invention, the phenomenon of rag material accumulation
may
in some embodiments be controlled by monitoring the fluid density in the
solvent extraction
apparatus and increasing the underflow component withdrawal rate from the
solvent extraction
apparatus if the fluid density of the material in the solvent extraction
apparatus increases above a
desired value. In some embodiments, the fluid density may be monitored by
monitoring the fluid
density of the intra-stage recycle component.
In the underflow component withdrawal rate differential aspect of the
invention,
transferring "additional" underflow material to the downstream solvent
extraction stage also
provides an opportunity for more mechanical energy to be imparted to the
potentially problematic
underflow material and in a countercurrent process, allows such underflow
material to be
subjected to an increased hydrocarbon diluent concentration in the downstream
solvent extraction
stage. This increased hydrocarbon diluent concentration may assist in reducing
the amount of rag
material (by shifting to a new phase equilibrium), may provide improved
settling in the
downstream solvent extraction apparatus because of the increased dilution of
the material in the
downstream solvent extraction apparatus. This may in turn result in an
improved quality of the
overflow component which is produced in the downstream solvent extraction
apparatus. If this
improved quality overflow component is recycled back to the previous solvent
extraction stage,
the improved quality of the overflow component may assist in minimizing
interphase development
such as rag material in the previous solvent extraction stage.
In the underflow component withdrawal rate differential aspect of the
invention,
maintaining the underflow component withdrawal rate in the final solvent
extraction stage at a
lower rate relative to the underflow component withdrawal rate in one or more
of the upstream
solvent extraction stages provides for a relatively greater overflow component
withdrawal rate in
the final solvent extraction stage. In a countercurrent process, where the
overflow component
from the final solvent extraction stage is recycled back to the previous
solvent extraction stage, the
relatively greater overflow component withdrawal rate in the final solvent
extraction stage
provides an increased opportunity to dilute the material in the previous
solvent extraction stage
and provides potentially improved separation in the previous solvent
extraction stage, which may
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result in an improved quality of the overflow component in the previous
solvent extraction stage
by increasing the bitumen phase residence time in the previous solvent
extraction stage.
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.
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