Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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METHODS FOR CREATING TRAFFICABLE OIL SANDS TAILINGS
TECHNICAL FIELD
[0001] The disclosure relates generally to the field of
resource extraction,
and more particularly to methods and processes associated with mining and the
extraction of bitumen and/or heavy oil from oil sands.
BACKGROUND
[0002] The extraction of bitumen, or heavy oil, from oil
sands is increasingly
relied upon as a means of meeting worldwide demand for oil.
[0003] The extraction of bitumen or heavy oil from mined
oil sands may be
accomplished using a variety of methods, including the Clark Hot Water
Extraction
process (and its various derivatives). However, the extraction of bitumen
using
techniques such as the Clark Hot Water Extraction method produces tailings, as
a
by-product of bitumen production, and the associated storage, treatment and
reclamation of the tailings presents various operational and environmental
costs to
the extraction of bitumen from oil sands. It is estimated that approximately
220
square kilometers of tailings ponds (including, for example, 1.1 billion cubic
meters
of mature fine tailings (MET), which may be a highly stable mixture of fine
clay
particles and water, and may, for example, have the consistency of yogurt)
exist in
Alberta, Canada, and the quantity of MET is estimated to be growing by
approximately 10% per year. Tailings ponds are toxic to plants and animals,
and the
reclamation of these tailings ponds are delayed indefinitely due to the
presence of
MET within the tailings ponds. As bitumen extraction is increasingly regulated
by
governmental authorities seeking to mitigate the environmental impact, there
is a
need for safe and efficient disposal of tailings. For example, the Alberta
Energy
Regulator (AER) Directive 074 (Tailings Performance Criteria and Requirements
for
Oil Sands Schemes), established on February 3, 2009, and its successor, the
Tailings Management Framework for Mineable Athabasca Oil Sands, seek to reduce
the growth of tailings accumulation
[0004] Improvement in the processing of oils sands, and
more particularly
the processing of tailings, is therefore desirable.
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SUMMARY
[0005] The disclosure describes methods for processing
oil sands and/or
tailings produced during extraction of bitumen from oil sands.
[0006] In one aspect, the disclosure describes a method
of processing oil
sands, the method comprising contacting aqueous material with oil sands to
produce
a suspension; separating a fraction of bitumen from the suspension to produce
a
bitumen-depleted suspension, wherein the bitumen-depleted suspension includes
solid particulate matter whose aggregation is being inhibited by surfactant;
reducing
the surfactant-effected inhibition to solid particulate matter aggregation in
the
bitumen-depleted suspension; and contacting the treated intermediate
suspension
with an aggregating agent to produce a treated suspension such that the solid
particulate matter is aggregated within the treated suspension.
[0007] In another aspect, the present disclosure
describes a method of
processing a bitumen-depleted suspension, wherein the bitumen-depleted
suspension includes solid particulate matter whose aggregation is being
inhibited by
surfactant, the method comprising: reducing the surfactant-effected inhibition
to solid
particulate matter aggregation in the bitumen-depleted suspension; and
contacting
the treated intermediate suspension with an aggregating agent to produce a
treated
suspension such that the solid particulate matter is aggregated within the
treated
suspension.
[0008] Further details of these and other aspects of the
subject matter of this
application will be apparent from the detailed description and drawings
included
below.
DESCRIPTION OF THE DRAWINGS
[0009] Reference is now made to the accompanying
drawings, in which:
[0010] FIG. 1 shows a flowchart of an exemplary method
for processing oil
sands;
[0011] FIG. 2 shows a flowchart of an exemplary method
for processing a
bitumen-depleted suspension; and
[0012] FIG. 3 is a process flow diagram of an exemplary
method for
processing oil sands.
2
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DETAILED DESCRIPTION
[0013]
Aspects of various embodiments are described through reference to
the drawings.
[0014]
Although terms such as "maximize", "minimize" and "optimize" may
be used in the present disclosure, it should be understood that such terms may
be
used to refer to improvements, tuning and refinements which may not be
strictly
limited to maximal, minimal or optimal.
[0015]
"Fine solid particulate matter is solid particulate matter having a
particle size of less than about 2 micrometres. In some embodiments, for
example,
the fine solid particulate matter includes silt and/or clay particles.
In some
embodiments, for example, the fine solid particulate matter includes clay
platelets,
such as, for example, clay platelets having a negative charge. In some
embodiments, for example, the fine solid particulate matter may comprise
colloidal
solids, or non-settleable solids.
[0016]
"Coarse solid particulate matter is solid particulate matter having a
particle size of greater than about 2 micrometers. In some embodiments, for
example, the coarse solid particulate matter may be sand particles that do not
break
apart under conditions where clay particles subjected to surfactant break
apart (such
as, for example, where clay particles subjected to surfactant break apart to
form into
a colloid). In some embodiments, for example, the coarse solid particulate
material
may, for example, include sand particles, silt and gravel.
[0017]
"Surfactant" is a material, compound or compounds, and functions to
inhibit, prevent or substantially prevent aggregation of the solid particulate
matter. In
some embodiments, for example, the surfactant includes one or more anionic
surfactants. In some embodiments, for example, the surfactant is one or more
anionic surfactants. In some embodiments, for example, the surfactant includes
a
carboxylate-functional surfactant, a sulfate/sulfonate functional surfactant,
or a
combination of a carboxylate-functional surfactant and a sulfate/sulfonate
functional
surfactant. In some embodiments, for example, the surfactant is a carboxylate-
functional surfactant, a sulfate/sulfonate functional surfactant, or a
combination of a
carboxylate-functional surfactant and a sulfate/sulfonate functional
surfactant.
[0018]
This disclosure is based in part on the surprising discovery that
surfactants released from bitumen and/or heavy oil extraction (for example,
under
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the conditions required for Clark Hot Water Extraction, and its various
derivatives
and related processes) interfere with any attempt to aggregate (for example,
by
coagulation, flocculation and settling the particles contained in the
tailings) the solid
particulate matter suspended in tailings required for the treatment and
reclamation of
the tailings. This may, for example, interfere with production of trafticable
deposits
(as defined by the Alberta Energy Regulator Directive 074 dated February 3,
2009)
and reuse of water in processes and methods of extracting bitumen. Trafficable
deposits may be a deposit typically created through a process involving self-
weight
consolidation, drying, enhanced drainage, and/or capping with minimum
undrained
shear strength of 5 kPa one year after deposition. The trafficable surface
layer may
have a minimum undrained shear strength of 10 kPa five years after active
deposition. The treatment of tailings to at least mitigate the formation of
fluid fine
tailings and mature fine tailings will permit higher recycle rates of water.
[0019] FIG:1 illustrates a flowchart of an exemplary
method 100 for
processing oil sands. Method 100 and/or parts thereof may be performed using
systems and devices known to those skilled in the art, and for example, those
systems and devices utilized in the field in the extraction of bitumen from
oil sands.
Method 100 and/or parts thereof may be performed in conjunction with other
methods herein disclosed. Method 100 may comprise contacting aqueous material
with oil sands to produce an intermediate suspension. The oil sands may, for
example, comprise a mixture of crude bitumen (or alternatively a semi-solid,
or more
viscous, form of crude oil), gravel, sand, silt and clay. In some embodiments,
for
example, the aqueous material includes water. In some embodiments, for
example,
the water is hot water. in some embodiments, for example the hot water
comprises
water at a temperature from about 75 degrees Celsius to about 95 degrees
Celsius.
In some embodiments, for example, the water is warm water. In some
embodiments,
for example, the warm water comprises water at a temperature from about 30
degrees Celsius to about 75 degrees Celsius. In some embodiments, for example,
the water is pH adjusted. in some embodiments, for example, the water is pH
adjusted to a range of about 8 to about 13. In some embodiments, for example,
the
water is pH adjusted to a range of about 9.5 to about 10. In some embodiments,
for
example, the suspension is a product of the Clark Hot Water Extraction
process, or
its various derivatives.
[0020] At least a fraction of the bitumen is separated
from the oil sands to
produce the bitumen-depleted suspension (see block 104). In this respect, the
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intermediate suspension is separated into a bitumen-rich phase and a bitumen-
depleted suspension. In some embodiments, for example, the separation is based
on differences in density between the bitumen-rich phase and the bitumen-
depleted
suspension. In some embodiments, for example, the separation includes
separation
effected by flotation.
[0021] The bitumen-depleted suspension includes a
suspended phase that
is suspended within an aqueous phase. The suspended phase includes solid
particulate matter. In some embodiments, for example, the solid particulate
material
includes fine solid particulate matter.
[0022] The bitumen-depleted suspension also includes
surfactant. At least a
fraction of the surfactant within suspension is functioning to inhibit
aggregation of the
solid particulate matter (such as, for example, fine solid particulate matter)
and
thereby interfering with the gravity settling of the solid particulate matter.
In some
embodiments, for example, a fraction of the surfactant of the suspension may
be
adsorbed to the solid particulate matter (such as, for example, fine solid
particulate
matter), and the adsorbed surfactant creates a negative net electrical charge
on the
solid particulate matter, which causes repulsion of the solid particulate
matter from
one another.
[0023] In some embodiments, for example, the bitumen-
depleted
suspension includes up to about 20 volume % of fine solid particulate matter,
based
on the total volume of the bitumen-depleted suspension. In some embodiments,
for
example, the bitumen-depleted suspension includes from about 5 volume % of
fine
solid particulate matter, based on the total volume of the bitumen-depleted
suspension, to about 15 volume % of fine solid particulate matter, based on
the total
volume of the bitumen-depleted suspension.
[0024] In some embodiments, for example, the bitumen-
depleted
suspension includes up to about 20 volume % of clay platelets, based on the
total
volume of the bitumen-depleted suspension. In some embodiments, for example,
the bitumen-depleted suspension includes from about 5 volume % of clay
platelets,
based on the total volume of the bitumen-depleted suspension, to about 15
volume
% of clay platelets, based on the total volume of the bitumen-depleted
suspension.
[0025] In some embodiments, for example, the bitumen-
depleted
suspension includes tailings produced during extraction of bitumen or heavy
oil from
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oil sands. Exemplary methods of extractions of bitumen or heavy oil from oil
sands
include the Clark Hot Water Extraction process and its various derivatives. In
some
embodiments, for example, the tailings include tailings obtained from a
tailings pond.
In those embodiments where the tailings includes tailings obtained from a
tailings
pond, in some of these embodiments, for example, the tailings comprise fluid
fine
tailings, mature fine tailings, or a combination of fluid fine tailings and
mature fine
tailings.
[0026] ln some embodiments, for example, the bitumen-
depleted
suspension includes fluid fine tailings. In some embodiments, for example, the
fluid
fine tailings include from about 5 volume % of fine solid particulate matter,
based on
the total volume of the fluid fine tailings, to about 15 volume % of fine
solid
particulate matter, based on the total volume of the fluid fine tailings. In
some
embodiments, for example, the fluid fine tailings are obtained from, or are
present
within, tailing ponds. In some embodiments, for example, the tailing ponds are
located within an oil sands mining operation, a bitumen extraction operation,
or a
heavy oil extraction operation. In some embodiments, for example, the fluid
fine
tailings may be a suspension of fine clay particulate matter in water that
does not
settle with coarse tailings in a tailings pond.
[0027] In some embodiments, for example, the bitumen-
depleted
suspension includes mature fine tailings. Mature fine tailings have a higher
density
than fluid fine tailings. In some embodiments, for example, the mature fine
tailings is
a composition including fine clay solid particulate matter and water. In some
embodiments, for example, the mature fine tailings include about 10 volume %
of
fine solid particulate matter, based on the total volume of the mature fine
tailings, to
about 20% by volume of fine solid particulate matter, based on the total
volume of
the mature fine tailings. In some embodiments, for example, the mature fine
tailings
settle, over a period of time, from the fluid fine tailings within a tailings
pond, such
as, for example, over a period of time of about two (2) years. In some
embodiments,
for example, the mature fine tailings are obtained from, or are present
within, tailing
ponds. In some embodiments, for example, the tailing ponds are located within
an
oil sands mining operation, a bitumen extraction operation, or a heavy oil
extraction
operation.
[0028] The method 100 further includes reducing the
surfactant-effected
inhibition to solid particulate matter aggregation within the bitumen-depleted
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suspension to produce a treated intermediate suspension (see block 106). In
some
embodiments, the reducing of the surfactant-effected inhibition to solid
particulate
matter aggregation includes reducing the surfactant-effected inhibition to
fine solid
particulate matter aggregation.
[0029] In some embodiments, for example, the reducing of
the surfactant-
effected inhibition to solid particulate matter aggregation (such as, for
example, fine
solid particulate matter aggregation) includes contacting the bitumen-depleted
suspension with an adsorbent such that at least a fraction of the surfactant
(dissolved within an aqueous phase of the bitumen-depleted suspension) becomes
adsorbed to the adsorbent to form an adsorbent-surfactant complex. In some
,
embodiments, for example, the contacting is effected over a period of at least
two
(2) hours, such as, for example, four (4) hours, such as, for example, six (6)
hours.
The contacting effects production of a treated intermediate suspension
including the
adsorbent-surfactant complex. In this respect, in some embodiments, for
example,
the treated intermediate suspension includes a solid phase, and the solid
phase
includes the absorbent-surfactant complex. In some embodiments, for example,
the
adsorbent agent comprises one or more of activated carbon, charcoal, silica
gel or
waste tire rubber granules.
[0030] In some embodiments, for example, sufficient
adsorbent is contacted
with the bitumen-depleted suspension such that at least 75% of the surfactant
(within the bitumen-depleted suspension) becomes adsorbed to the adsorbent to
form an adsorbent-surfactant complex, In some embodiments, for example,
sufficient adsorbent is contacted with the bitumen-depleted suspension such
that at
least 90% of the surfactant (within the bitumen-depleted suspension) becomes
adsorbed to the adsorbent to form an adsorbent-sUrfactant complex.
[0031] In some embodiments, for example, the amount of
adsorbent that is
contacted with the bitumen-depleted suspension is based upon at least the
sensed
amount (e.g. by a sensor), or determined amount, of surfactant. In some
embodiments, for example, prior to the contacting of the adsorbent with the
bitumen-
depleted suspension, the concentration of surfactant within the bitumen-
depleted
suspension is sensed such that an amount of surfactant within the bitumen-
depleted
suspension is determined, and the amount of adsorbent that is contacted with
the
bitumen-depleted suspension is based upon at least the determined amount of
surfactant within the bitumen-depleted suspension.
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[0032]
In some embodiments, for example, the reducing of the surfactant-
effected inhibition to solid particulate matter aggregation (such as, for
example, fine
solid particulate matter aggregation) includes subjecting the bitumen-depleted
suspension to flotation. During flotation, bitumen-depleted suspension is
separated
into an overflow and an underflow. In some embodiments, for example, the
underflow includes (or, in some embodiments, for example, is defined by) the
treated intermediate suspension. In some embodiments, for example, flotation
may
comprise contacting the bitumen-depleted suspension with at least air. In some
embodiments, for example, the flotation process may be performed within an
enclosure wherein air bubbles are introduced at the bottom of the enclosure
such
that the air bubbles come into contact with bitumen-depleted suspension as
they rise
through the aqueous phase of the bitumen-depleted suspension. Without being
limited to theory, as the air bubbles rise to the surface, surfactants will
become
associated with the air bubbles and be carried to the surface of the aqueous
phase.
The surfactant may be then removed by skimming techniques known to those
skilled
in the art.
10033]
In some embodiments, for example, after flotation, at least a fraction
of the underflow may include residual surfactant, and the underflow may be
further
treated by contacting with the adsorbent, as described above, to produce the
treated
intermediate suspension. In some of these embodiments, for example, the amount
of adsorbent that is contacted with the underflow suspension is based upon at
least
the amount of residual surfactant within the underflow.
In some of these
embodiments, for example, prior to the contacting of the adsorbent with the
underflow, the concentration of surfactant within the underflow is sensed
(e.g. by a
sensor) such that an amount of surfactant within the underflow is determined,
and
the amount of adsorbent that is contacted with the underflow is based upon the
determined amount of surfactant within the underflow.
[0034]
In some embodiments, for example, the method 100 may further
include, prior to the reducing of the surfactant-effected inhibition to solid
particulate
matter aggregation within the bitumen-depleted suspension, separating at least
a
fraction of the coarse solid particulate material from the bitumen-depleted
suspension. The coarse solid particulate matter may, in some circumstances and
conditions, settle quickly and easily once removed from the bitumen-depleted
suspension, to effect production of trafficable deposits, and may be disposed
of, or
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deposited within a land full, without further processing. In some embodiments,
for
example, the coarse solid particulate material may be separated from the
bitumen
depleted suspension using a hydrocyclone, or via another device or technique
known to those skilled in the art. Removal of at least a fraction of the
coarse solid
particulate matter may, in some embodiments, for example, reduce the cost and
duration of tailings processing when compared to processes wherein their
removal is
not performed, as time and/or processing reagents/inputs may be saved.
[0035] In some embodiments, for example, prior to the reducing of the
surfactant-effected inhibition to solid particulate matter aggregation within
the
bitumen-depleted suspension to produce a treated intermediate suspension, the
bitumen-depleted suspension is conditioned. In some embodiments, for example,
the conditioning is such that the bitumen-depleted suspension is pre-disposed
for
the reducing the surfactant-effected inhibition to solid particulate matter
aggregation.
In this respect, in some embodiments, for example, the conditioning is such
that the
bitumen-depleted suspension is pre-disposed for the contacting with an
adsorbent.
Also, in this respect, in some embodiments, for example, the conditioning is
such
that the bitumen-depleted suspension is pre-disposed for the treatment by
flotation.
In some embodiments, for example, the conditioning is such that the bitumen-
depleted suspension is pre-disposed such that, after the reducing the
surfactant-
effected inhibition to solid particulate matter aggregation within the bitumen-
depleted
suspension to produce a treated intermediate suspension, the solid particulate
material of the treated intermediate suspension is pre-disposed for
aggregation
when the treated intermediate suspension is contacted with an aggregating
agent.
In some embodiments, for example, the conditioning includes at least one of
adding
aqueous material, adding water, applying heat, adding chemicals, applying
electrical
forces, and applying mechanical forces to the bitumen-depleted suspension.
Such
conditioning, for example, may be helpful to achieve a desired viscosity
and/or a
desired consistency of the bitumen-depleted suspension. In some embodiments,
for
example, the conditioning is effected when the bitumen-depleted suspension
includes fluid fine tailings or mature fine tailings. Such tailings may
contain relatively
less water, and are relatively more viscous. In some embodiments, for example,
such tailings are gel-like, and may have the consistency of yogurt. In this
respect,
such tailings are disposed in a condition which makes it difficult to effect a
reduction
in the surfactant-effected inhibition to solid particulate matter aggregation
(such as
by surfactant removal) or aggregation of solid particulate material (after the
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reduction in the surfactant-effected inhibition to solid particulate matter
aggregation
within the bitumen-depleted suspension). In such cases, the conditioning may
mitigate such difficulties. In some embodiments, for example, the conditioning
may
not be required for bitumen-depleted suspensions that have been recently
produced.
[0036] The treated intermediate suspension is contacted
with an aggregating
agent to produce a treated suspension such that at least a fraction of the
suspended
solid particulate matter becomes aggregated to produce aggregated solid
particulate
material within the treated suspension(see block 108). In some embodiments,
for
example, the aggregating agent is a coagulant, and the contacting the treated
intermediate suspension with the coagulant is such that the solid particulate
matter
is aggregated. In some embodiments, for example, the aggregated solid
particulate
matter includes fine solid particulate material.
[0037] In some embodiments, for example, the method 100
further includes
agitating or mixing the treated intermediate suspension when contacting the
treated
intermediate suspension with the aggregating agent.
[0038] In some embodiments, for example, the aggregating
agent may be
added to the treated intermediate suspension contemporaneously with the
agitating
or mixing the treated intermediate suspension. The agitation or mixing may,
for
example, occur within an enclosure wherein the treated intermediate suspension
is
contained therein. Insufficient mixing of the treated intermediate suspension
upon
contacting the treated intermediate suspension with the aggregating agent may
prevent adequate aggregation of the solid particulate matter (including fine
solid
particulate matter), while over-mixing may shear the newly aggregated solid
particulate material (including newly aggregated fine solid particulate
matter) into
non-aggregated solid particulate matter. In some embodiments, for example, the
mixing, which may be known as flash mixing to those skilled in the art, may be
sustained for between about 30 seconds to about 60 seconds.
[0039] Subsequent to the initial agitation or mixing of
the aqueous phase, in
some embodiments, for example, method 100 may comprise a second agitation or
mixing of the treated suspension after contacting the treated intermediate
suspension with the aggregating agent. The second agitation or mixing of the
treated suspension, after contacting the treated intermediate suspension with
the
aggregating agent, may effect further aggregation of the solid particulate
matter
(including further aggregation of the fine solid particulate matter) without
shearing
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apart the aggregated solid particulate material (including aggregated fine
solid
particulate matter). In some embodiments, for example, the second agitation or
mixing may comprise flocculation.
[0040]
In some embodiments, for example, the second agitation or mixing is
applied to the treated suspension such that the treated suspension is at a
speed of
about I ft/sec. In some embodiments, for example, the second agitation or
mixing
may occur in an enclosure, for example a basin, comprising a plurality of
compartments, each compartment having decreasing mixing speed relative to the
compartment preceding it. In some embodiments, for example, as the treated
suspension moves from compartment to compartment, aggregation of the solid
particulate matter (such as, for example, the fine solid particulate matter)
may occur
such that increasingly large floc may form. In some embodiments, for example,
flocculation may be sustained for about thirty to forty-five minutes.
[0041]
In some embodiments, for example, coagulation and flocculation, as
it relates to the aggregation of the solid particulate matter (such as, for
example, fine
solid particulate matter), may be based on the electrical charges of the solid
particulate matter. In some embodiments, for example, such solid particulate
matter
may have a net negative charge when suspended in the aqueous phase, and
accordingly, solid particulate matter may repel each other. In this respect,
in some
embodiments, for example, the aggregating agent may effect coagulation by
destabilizing or neutralizing the charge of such solid particulate matter. The
amount
of aggregating agent necessary to effect aggregation may depend on the zeta
potential, a measurement of the magnitude of electrical charge surrounding the
colloidal solid particulate matter. If the zeta potential is large, then more
aggregating
agent may be necessary.
[0042]
In some embodiments, for example, the aggregating agent may be
one or more compounds, materials or agents that may initiate, promote, cause
or
enhance aggregation of the solid particulate matter (such as, for example, the
fine
solid particulate matter), for example, by coagulation and flocculation. In
some
embodiments, for example, the aggregating agent may comprise a coagulant to
effect destabilization of the solid particulate matter in solution.
In some
embodiments, for example, the coagulant may comprise a chemical coagulant or
an
electrochemically-generated coagulant.
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[0043] In some embodiments, for example, the aggregating
agent enhances
flocculation. In some embodiments, for example, the aggregating agent may, for
example, comprise a metallic salt or a cationic polymer. In some embodiments,
for
example, anionic or non-ionic polymers may not be appropriate as aggregating
agents, as a positive charge is required to neutralize the net negative charge
that
may be present in relation to the solid particulate matter (such as, for
example, fine
solid particulate matter). In some embodiments, for example, the aggregating
agent
may, for example, comprise one or more of aluminum sulfate, ferric sulfate,
ferrous
sulfate, ferric chloride, cationic polymer, calcium hydroxide, calcium oxide,
sodium
aluminate, bentonite, calcium carbonate or sodium silicate.
[0044] The aggregation of the solid particulate matter
(such as, for example,
fine solid particulate matter) may also be affected by characteristics of the
aqueous
phase, such as pH, alkalinity, temperature, duration of mixing or agitation of
the
treated intermediate suspension, flow characteristics during mixing and zeta
potential. In some embodiments, for example, the aqueous phase may be
alkaline.
In some embodiments, for example, the aggregating agent comprises aluminum
sulfate and the aqueous phase is alkaline.
[0045] In those embodiments where the treated
intermediate suspension is
produced by the contacting of the bitumen-depleted suspension with the
adsorbent,
or where the treated intermediate suspension is produced by the contacting of
the
underflow of a flotation operation, with the adsorbent, in some of these
embodiments, for example, the method 100 further comprises, prior to
contacting of
the treated intermediate suspension with the aggregating agent, separating the
adsorbent-surfactant complex from the treated intermediate suspension. In some
embodiments, for example, the adsorbent-surfactant complex may be removed if
it
interferes with or inhibits aggregation of the solid particulate matter (such
as, for
example, fine solid particulate matter). The adsorbent-surfactant complex may,
for
example, be removed if it interferes with or inhibits the function of the
aggregating
agent, which will be further described below. In some embodiments, for
example,
the adsorbent-surfactant complex may be removed using a hydro-cyclone. In
other
embodiments, for example, the adsorbent-surfactant complex may be removed
using filtering media. In other embodiments, for example, the adsorbent-
surfactant
complex may be removed by collecting it from the surface of the treated
intermediate suspension,
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[0046] In some embodiments, for example, method 100 may
further
comprise separating a solids-rich material from the treated suspension_ The
solids-
rich material includes at least a fraction of the aggregated solid particulate
material.
In some embodiments, for example, such as those embodiments where the
bitumen-depleted suspension is contacted with an adsorbent such that at least
a
fraction of the surfactant becomes adsorbed to the adsorbent to produce an
adsorbent-surfactant complex, the solids-rich material includes the surfactant-
adsorbent complex. In some embodiments, for example, the separating is
effected
by gravity settling.
[0047] In some embodiments, for example, the gravity
settling, for effecting
separation of the solids-rich material from the treated suspension, may be
effected
within a settling zone_ In some embodiments, for example, the settling zone is
disposed within a sedimentation basin or pond. In some embodiments, for
example,
the settling is conducted over a time interval that is sufficient such that an
aqueous
phase becomes separated from the treated suspension such that the aqueous
phase is removable from the settling zone without substantially removing the
solids-
rich material. In some embodiments, for example, the settling time ranges from
one
(1) hour to seven (7) days. In some embodiments, for example, the settling
time is
from one (1) hour to 48 hours. The aqueous phase may in some embodiments, for
example, be recycled or reused in method 100 or in other related oil sands
processes. In some embodiments, for example, method 100 enables water recycle.
In some embodiments, for example, method 100 enables greater levels of water
recycle compared to prior art processes.
[0048] In this respect, in some embodiments, for example,
the method 100
further comprises separating at least a fraction of an aqueous phase from the
treated suspension, and recycling the separated aqueous phase such that the
aqueous material being contacted with the oil sands includes the separated
aqueous
phase.
[0049] In some embodiments, for example, the solids-rich
material that
remains in the enclosure may be periodically removed and placed in a landfill
where
further drying may take place to produce a final trafficable deposit. In some
embodiments, for example, the solids-rich material remaining in the enclosure
may
be permitted accumulate over multiple settling cycles before being placed in a
landfill where further drying may take place to produce a final trafficable
deposit.
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[0050] In this respect, in some embodiments, for example, the reducing of
the surfactant-effected inhibition to solid particulate matter aggregation in
the
bitumen-depleted suspension is such that, the aggregation of the solid
particulate
matter (such as, for example, the fins solid particulate matter), effected in
response
to the contacting of the produced treated intermediate with the aggregating
agent, is
such that gravity settling of a solid-rich material, including the aggregated
solid
particulate matter, is effected, and such that, after the separation of the
solid-rich
material from the treated intermediate, and after sufficient drying of the
separated
solid-rich material, production of a trafficable deposit is effected.
[0051] Turning now to FIG. 2, there is disclosed a method 200 of processing
a bitumen-depleted suspension, the bitumen-depleted suspension comprising a
suspended phase that is suspended within an aqueous phase. The suspended
phase includes solid particulate matter, such as, for example, fine solid
particulate
matter. The bitumen-depleted suspension also includes surfactant At least a
fraction of the surfactant within the suspension is functioning to inhibit
aggregation of
the solid particulate matter and thereby interfering with the gravity settling
of the
solid particulate matter. In some embodiments, for example, a fraction of the
surfactant of the suspension is adsorbed to the solid particulate matter, and
the
adsorbed surfactant effects repulsion of other solid particulate matter.
[0052] Method 200 and/or parts thereof may be performed using systems
and devices known to those skilled in the art. Method 200 and/or parts thereof
may
be performed in conjunction with other methods herein disclosed.
[0053] Method 200 comprises reducing the surfactant-effected inhibition to
solid particulate matter aggregation in the bitumen-depleted suspension to
produce
a treated intermediate suspension (see block 202); and contacting the treated
intermediate suspension with an aggregating agent to produce a treated
suspension
such that at least a fraction of the suspended solid particulate matter (such
as, for
example, the fine solid particulate matter) is aggregated within the treated
suspension (see block 204).
[0054] FIG. 3 illustrates a process flow diagram of an exemplary process
for
treating oil sands, and mitigates the surfactant-effected inhibition to solid
particulate
matter aggregation within tailings produced within that process.
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[0055] Bitumen ore is mixed with heated water, chemicals
(including, for
example, NaOH, to increase pH) and air. This mixture 12 is conducted through a
Hydrotransport pipeline for transport to a primary separation cell (PSC) 102.
Along
the way, the bitumen is washed off of the sand particles and combined with the
air
to create a bitumen froth.
[0056] Within the PSC 102, the bitumen froth, middlings
(residual bitumen,
fines & water), and coarse tailings and water, are separated by gravity. The
bitumen
froth 14 is skimmed from the top, deaerated, and then conducted to a holding
tank
104, prior to being conducted to a froth treatment facility 106. The coarse
tailings
and water settles to the bottom of the PSC 102 and are then conducted as
stream
18 to the tailings pond 120. The middlings 16 are subjected to flotation
within a
flotation circuit 108 where additional bitumen is recovered as a froth and is
recycled
,
as a stream $8 to the PSC 102. The tailings 30 include fine particulate
matter,
water, and relatively significant amounts of surfactant.
[0057] Within the froth treatment facility 106,
hydrocarbon solvent is added
to absorb and dilute the bitumen from the froth mixture in order to separate
the
bitumen from the fine particulate matter and water. Both of the overflow 20
and the
underflow 22 are heated within respective solvent recovery units 110, 112 to
evaporate solvent to produce, respectively, bitumen product 24 and froth
treatment
tailings 26, while also producing recovered solvent streams 28, 30. The froth
treatment tailings 26 include fine particulate matter, water, and relatively
significant
amounts of surfactant. The recovered solvent is stored in a holding tank 114.
(00581 Both of the tailings 26, 30 are conducted to a
facility 116 for effecting
reducing of the surfactant-effected inhibition to solid particulate matter
aggregation,
as described above. The resulting treated intermediate suspension 32 is
conducted
to the coagulation, flocculation and settling facility 118, where the treated
intermediate suspension $2 is contacted with an aggregating agent to produce a
treated suspension such that at least a fraction of the suspended solid
particulate
matter becomes aggregated to produce aggregated solid particulate material
within
the treated suspension. The solids-rich material 34 is then separated from the
treated suspension, and may be sent to landfill. The solids-rich material
includes at
least a fraction of the aggregated solid particulate material, and may also,
in some
embodiments, include the adsorbent-surfactant complex. In some embodiments,
for
example, the separating is effected by gravity settling. The aqueous phase $6
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also separated from the treated suspension, and then recycled such that the
aqueous material being contacted with the oil sands (for example, as part of
the
Clark Hot Water Extraction process) includes the separated aqueous phase.
(0059] The above description is meant to be exemplary
only, and one skilled
in the relevant arts will recognize that changes may be made to the
embodiments
described without departing from the scope of the invention disclosed. For
example,
the blocks and/or operations in the flowcharts and drawings described herein
are for
purposes of example only. There may be many variations to these blocks and/or
operations without departing from the teachings of the present disclosure. For
instance, the blocks may be performed in a differing order, or blocks may be
added,
deleted, or modified. The present disclosure may be embodied in other specific
forms without departing from the subject matter of the claims. Also, one
skilled in the
relevant arts will appreciate that while the systems, devices and assemblies
disclosed and shown herein may comprise a specific number of
elements/components, the systems, devices and assemblies Could be modified to
include additional or fewer of such elements/components. The present
disclosure is
also intended to cover and embrace all suitable changes in technology.
Modifications which fall within the scope of the present invention will be
apparent to
those skilled in the art, in light of a review of this disclosure, and such
modifications
are intended to fall within the appended claims.
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