Note: Descriptions are shown in the official language in which they were submitted.
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PROCESS FOR RECOVERING BITUMEN FROM OIL SANDS ORE BY FROTHING AND ADDITION OF
CEMENT POWDER
FIELD OF THE ART
[0001] The present embodiments relate to processes recovering bitumen from oil
sands ore wherein cement is used as a process aid.
BACKGROUND
[0002] Bituminous sands - colloquially known as oil sands (and sometimes
referred
to as tar sands) - are a type of unconventional petroleum deposit. The sands
contain naturally
occurring mixtures of sand, clays, water, and a dense and extremely viscous
form of
petroleum technically referred to as bitumen (or colloquially "tar" due to its
similar
appearance, odor, and color). Oil sands are found in large amounts in many
countries
throughout the world, but are found in extremely large quantities in Canada
and Venezuela.
Oil sand deposits in northern Alberta in Canada contain approximately 1.6
trillion barrels of
bitumen, and production from oil sands mining operations is expected to reach
1.5 million
barrels of bitumen per day by 2020.
[0003] Oil sands reserves have only recently been considered to be part of the
world's oil reserves, as higher oil prices and new technology enable them to
be profitably
extracted and upgraded to usable products. They are often referred to as
unconventional oil or
crude bitumen, in order to distinguish the bitumen extracted from oil sands
from the free-
flowing hydrocarbon mixtures known as crude oil traditionally produced from
oil wells.
[0004] Conventional crude oil is normally extracted from the ground by
drilling oil
wells into a petroleum reservoir, and allowing oil to flow into them under
natural reservoir
pressures, although artificial lift and techniques such as water flooding and
gas injection arc
usually required to maintain production as reservoir pressure drops toward the
end of a field's
life. Because extra-heavy oil and bitumen flow very slowly, if at all, toward
producing wells
under normal reservoir conditions, the sands may be extracted by either strip
mining or the oil
made to flow into wells by in situ techniques which reduce the viscosity such
as by injecting
steam, solvents, and/or hot air into the sands. These processes can use more
water and require
larger amounts of energy than conventional oil extraction, although many
conventional oil
fields also require large amounts of water and energy to achieve suitable
production rates.
[0005] The original process for extraction of bitumen from the sands was
developed by Dr. Karl Clark, working with Alberta Research Council in the
1920s. Today,
the producers doing surface mining use a variation of the Clark Hot Water
Extraction
(CHWE) process. In this process, the ores are mined using open-pit mining
technology. The
mined ore is then crushed for size reduction. Hot water at 40-80 C is added to
the ore and the
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formed slurry is conditioned and transported, for example using a piping
system called
hydrotransport line, to the extraction unit, for example to a primary
separation vessel (PSV)
where bitumen may be recovered by flotation as bitumen froth. The
hydrotransport line may
be configured to condition the oil sand while moving it to the extraction. The
water used for
hydrotransport is generally cooler(but still heated) than in the tumblers or
conditioning
drums.
[0006] The displacement and liberation of bitumen from the sands is achieved
by
wetting the surface of the sand grains with an aqueous solution containing a
caustic wetting
agent, such as sodium hydroxide, sodium carbonate, sodium silicate or calcium
hydroxide.
The resulting strong surface hydration forces operative at the surface of the
sand particles
give rise to the displacement of the bitumen by the aqueous phase. Once the
bitumen has
been displaced and the sand grains are free, the phases can be separated by
froth flotation
based on the natural hydrophobicity exhibited by the free bituminous droplets
at moderate pH
values (Hot water extraction of bitumen from Utah tar sands, Sepulveda et al.
S. B. Radding,
ed., Symposium on Oil Shale, Tar Sand, and Related Material - Production and
Utilization of
Synfuels: Preprints of Papers Presented at San Francisco, California, August
29 - September
3,1976; vol. 21, no. 6, pp. 110-122 (1976)).
[0007] The recovered bitumen froth generally consists of about 60% bitumen,
30%
water and 10% solids by weight. The recovered bitumen froth may be cleaned to
reject the
contained solids and water to meet the requirement of downstream upgrading
processes.
Depending on the bitumen content in the ore, between 90 and 100% of the
bitumen can be
recovered using modern hot water extraction techniques.
[0008] The amount of bitumen and quality of the froth may be dependent, for
example, on the bitumen's ability to separate from sand gains and attach to
air. It has been
observed that when the pH of the process is increased to between 8-10, organic
acids in the
bitumen may be neutralized into natural surfactants. These surfactants improve
bitumen-air
attachment by lowering interfacial tension and they separate the bitumen from
sand grains by
increasing interfacial charges. This improves the amount of bitumen which is
recovered in the
primary flotation process and helps to reduce the amount of solid particulate
which is
included in the froth.
[0009] Sodium hydroxide is used commercially to provide the alkaline
environment
for the CHWE process. Other inorganic bases such as sodium silicate, sodium
carbonate,
ammonia, and sodium tripolyphosphate have been evaluated and found to be
inferior to
NaOH, because, for example, they require a higher concentration or were unable
to provide
the same level of recovery as NaOH. Several other chemical classes of reagents
have been
proposed to improve bitumen recovery and froth quality. These include
surfactants,
flocculants, polymeric dispersants, and organic solvents. These approaches
have been found
to provide varying levels of success in laboratory tests, but generally NaOH
is still the most
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economical choice and therefore the commercially preferred process aid. Sodium
hydroxide is, however,
extremely corrosive and highly reactive, requiring specialized engineering
controls, protective equipment and
personal hygiene measures. Use of NaOH also may result in accumulation of
sodium ions in recycled water, which
can cause dispersion of higher clays and can produce tailings with poor
geotechnical properties that turn into
mature fine tailings. This is especially true for low grade and oxidized ores,
which present the greatest challenges
in bitumen recovery and produce the major portion of fine tailings.
[0010] US Patent Publication No. 2008/0223757 discloses a method for enhancing
the efficiency of
bitumen recovery from oil sands ore, said method comprising the step of mixing
lime into an oil sands ore-water
slurry in association with a slurry-based bitumen extraction process.
[0011] The description herein of certain advantages and disadvantages of known
methods and
compositions is not intended to limit the scope of the present disclosure.
Indeed, the present embodiments may
include some or all of the features described above without suffering from the
same disadvantages.
BRIEF SUMMARY
[0012] Disclosed herein are processes for recovering bitumen from oil sands
ore wherein cement is used
as a process aid. In one aspect, a process is provided for recovering bitumen
from oil sands ore, comprising: (i)
adding cement to an oil sands ore-water slurry; and (ii) liberating bitumen.
In another aspect, a process is provided
for extracting bitumen from an oil sand ore, comprising: (i) mixing oil sands
ore with water or an aqueous solution
to form a slurry; (ii) aerating the slurry to form a froth containing bitumen
within the slurry; (iii) separating the
froth from the slurry; (iv) adding cement to the slurry prior to or during one
or more of the preceding steps; and
(v) liberating bitumen from the froth. In particular embodiments, the cement
comprises one or more types of
hydraulic cements, such as Portland cement. It is further provided, a process
for recovering bitumen from oil sands
ore, comprising: (i) mixing oil sands ore with water or an aqueous solution to
form a slurry; (ii) aerating the slurry
to form a froth containing bitumen within the slurry; (iii) separating the
froth from the slurry; (iv) adding a cement
comprising one or more hydraulic cements that comprises calcium, aluminum,
silicon, oxygen and/or sulfur to an
oil sands ore-water slurry prior to or during one of the process steps; and
(v) liberating bitumen.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] Figure 1 shows the bitumen recovery data as a function of time for low
grade ore sample LG2
treated by sodium hydroxide and API class A cement (Cem A).
[0014] Figure 2 shows the bitumen recovery rate as a function of added API
class A cement.
100151 Figure 3 shows the bitumen recovery as a function of time for low grade
ore sample LG3 when pH
of water was adjusted to 8.5 and 10.0 using sodium hydroxide and API class A
cement.
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DETAILED DESCRIPTION
[0016] Disclosed herein are processes for enhancing recovery of bitumen from
oil
sands ore. In particular, exemplary processes for the recovery of bitumen from
oil sands ore
involve a water-based extraction process whereby a cement is added to a oil
sands ore-water
slurry. The water-based extraction process of oil sands refers to any known
extraction process
for producing aqueous tailings, including but not limited to the Clark Hot
Water Extraction
(CHWE) process, a hot water flotation process, or the like.
[0017] It has been discovered that cement, such as a hydraulic cement like
Portland
cement, can be used to adjust alkalinity of the oil sand ore-water slurry to
enhance the
efficiency of bitumen recovery in an extraction process. Cement can be an
economical
process aid, particularly compared to sodium hydroxide. In addition, the
handling and storage
of cement is relatively safe when compared to corrosive sodium hydroxide. The
cement, as
used herein, may make fine and ultrafine solids more hydrophilic and
agglomerated. It also
may facilitate bitumen-air bubble attachment and thus improve bitumen
flotation.
[0018] Cement
[0019] In exemplary embodiments, the cement process aid may be any of a
variety
of cements and pozzalanic materials. In one embodiment, the cement contains
one or more
hydraulic cements. Exemplary hydraulic cements include Portland cement,
Portland-based
cement, pozzolana cement, gypsum cement, high alumina cement, slag cement,
silica cement,
kiln dust or mixtures thereof. Exemplary Portland cements may be those
classified as class A,
C, H and G cements according to American Petroleum Institute (API)
specification for
materials and testing for well cements. They can also be classified by ASTM
C150 or EN 197
in classes of I, II, III, IV and V. In one embodiment, the cement is a
hydraulic cement that
comprises calcium, aluminum, silicon, oxygen and/or sulfur which may set and
harden by
reaction with water. In one embodiment the cement is an alkaline cement. In a
particular
embodiment, the cement comprises a mixture of two or more hydraulic cements..
[0020] In one embodiment, the cement comprises one or more types of Portland
cement. Portland cement is the most common type of cementitious material used
around the
world. It consists mainly of calcium silicates and aluminates and some iron-
containing
phases. When mixed with water, Portland cement undergoes various hydration
reactions
resulting in raised pH as well as generation of new species including calcium
silicate hydrates
(CSHs). CSH may bind strongly to other mineral grains, resulting in a setting
process.
[0021] Portland cement (also referred to as Ordinary Portland Cement or OPC)
is a
basic ingredient of concrete, mortar, stucco and most non-specialty grout.
Portland cement is
a mixture that results from the calcination of natural materials such as
limestone, clay, sand
and/or shale. In particular, Portland cement comprises a mixture of calcium
silicates,
including Ca3Si05 and Ca2SiO4, which result from the calcination of limestone
(CaCO3) and
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silica (SiO2). This mixture is known as cement clinker. In order to achieve
the desired setting
qualities in the finished product, calcium sulfate (about 2-8%, most typically
about 5%),
usually in the form of gypsum or anhydrite, is added to the clinker and the
mixture is finely
ground to form the finished cement powder. For example, a typical bulk
chemical
composition of Portland cement is about 61 to about 67 wt% calcium oxide
(CaO), about 12
to about 23 wt% silicon oxide (SiO2), about 2.5 to about 6 wt% aluminum oxide
(A1201),
about 0 about 6 wt% ferric oxide (Fe2O3) and about 1.5 about 4.5 wt% sulfate.
The properties
of Portland Cement can be characterized by the mineralogical composition of
the clinker.
Major clinker phases present in Portland cements include: Alite (3CaO.Si02),
Belite
(2CaO.Si09), Aluminate (3Cao.A1203) and Ferrite (4Ca0. A1203 .Fe2O3).
[0022] In an exemplary embodiment, the cement is a fine powder mixture which
contains more than 90% Portland cement clinker, calcium sulfate and up to 5%
minor
constituents (see European Standard EN197.1).
[0023] During the preparation of the cement, a grinding process may be
controlled
to obtain a powder with a broad particle size range, in which typically 15% by
mass consists
of particles below 5 lam diameter, and 5% of particles above 45 [tm. The
measure of particle
fineness usually used is the "specific surface area", which is the total
particle surface area of a
unit mass of cement. The rate of initial reaction (up to 24 hours) of the
cement on addition of
water is directly proportional to the specific surface area. Typical values
are 320-380 m2-kg 1
for general purpose cements, and 450-650 m2-kg-I for "rapid hardening"
cements.
[0024] Bitumen Recovery/Extraction Processes
[0025] In an exemplary embodiment, a process for enhancing the efficiency of
bitumen recovery from oil sands ore comprises adding water and cement to the
oil sands ore
which contains bitumen.
[0026] In one embodiment, a process for recovering bitumen from oil sands ore
includes: (i) adding cement to an oil sands ore-water slurry; and (ii)
liberating bitumen.
[0027] In another embodiment, a process for extracting bitumen from an oil
sand
ore includes: (i) mixing oil sands ore with water or an aqueous solution to
form a slurry; (ii)
aerating or conditioning the slurry to form a froth containing bitumen within
the slurry; (iii)
separating the froth from the slurry; (iv) adding cement to the slurry prior
to or during one or
more of the preceding steps; and (v) liberating bitumen from the froth.
[0028] In exemplary embodiments, the cement process aid may be added in any
mixing, conditioning, or separation step in the bitumen recovery process. In
view of the
embodiments described herein, it will be understood that the cement process
aid could be
added at other points in the bitumen recovery/extraction process as necessary
or desired.
[0029] In one embodiment, the cement may be added to the oil sand ore-water
slurry during any point before or during the mixing stage. In exemplary
embodiments,
mixing of the ore-water slurry may be achieved by any known process or
apparatus. For
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example, after the oil sands ores have been mined and crushed, the oil sands
ores may be
transported by conveyor to a slurry preparation plant, where hot water is
added to make the
oil sand ore-water slurry. In one embodiment, the oil sands ore may be low
grade ore. In one
embodiment, the oil sands ore may be high grade ore. In exemplary embodiments,
the
temperature of the water and/or the slurry may be any temperature as necessary
or desired. In
an exemplary embodiment, the temperature of the water and/or the slurry may be
elevated to
provide an effective amount of heat to the slurry to substantially release the
bitumen from
sand surface. In one embodiment, the water or aqueous solution used in the
process may be
between at a temperature of about 0 C to about 100 C; 0 C to about 90 C; about
20 C to
about 90 C; about 40 C to about 90 C; or about 40 C to about 60 C. In
exemplary
embodiments, depending, for example, on the temperature of the water, and/or
the
availability of thermal energy in the process, the temperature of the slurry
may be elevated to
and/or maintained at about 40 C to about 60 C. In the exemplary embodiments,
the cement
may be added before or during any of the mixing and conditioning stages
described above, or
their respective equivalents.
[0030] In one embodiment, the cement may be added to the oil sand ore-water
slurry during any point before or during a conditioning stage. Conditioning of
the slurry, as
described herein, may include further mixing or churning of the slurry,
aeration of the slurry
to form a froth, breaking of lumps in the slurry into smaller lumps,
liberation of bitumen from
sand grains, breaking of bitumen into smaller droplets, attaching liberated
bitumen droplets to
air bubbles, mixing the slurry with optional additives and other process aids,
or the like.
Generally, the effect of the conditioning stage is to enhance or maximize the
liberation of
bitumen from the sand grains and separation of bitumen or the froth containing
bitumen from
the slurry. Conditioning of the slurry may be achieved by any means known in
the art and is
not limited to the embodiments described herein.
[0031] In exemplary embodiments, after the slurry has been prepared and mixed,
the ore-water slurry may be conditioned by any known process or apparatus. For
example,
after the slurry is formed, the slurry may be transported through a slurry
hydrotransport
pipeline, which may be used to condition the slurry. In the slurry
hydrotransport pipeline, the
hydrodynamic forces from speed of the slurry may liberate bitumen from the
sand grains,
break the liberated bitumen into smaller droplets, and promote attachment of
the liberated
bitumen droplets to entrained air bubbles. In exemplary embodiments, the size,
shape,
configuration, and length of the hydrotransport pipeline may be predetermined
to provide any
necessary or desired results. For example, the length of the hydrotransport
pipeline may be
determined, at least in part, on the processing plant location, the slurry
temperature, the initial
lump size, or other conditions that may affect the conditioning of the slurry.
In some
embodiments, the hydrotransport pipeline may be up to about 5 kilometers. The
speed of the
slurry through the hydrotransport pipeline may be predetermined to provide any
necessary or
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desired result. For example, in an exemplary process, the slurry is
transported through the
pipeline at about 3 to about 5 meters per second. In the exemplary
embodiments, the cement
may be added before or during any of the mixing and conditioning stages
described above, or
their respective equivalents.
[0032] Aerating the slurry (or a derivative of the slurry) may be achieved by
any
means know in the art. In exemplary embodiments, aerating the slurry promotes
the
formation of froth and may be achieved, for example by mixing or churning the
slurry in a
mixing or transport vessel or apparatus, such as the transport of the slurry
in a slurry
hydrotransport pipeline. In some embodiments, the slurry or a derivative
thereof may be
aerated, for example, by sparging the slurry or derivative thereof in a vessel
or apparatus
(e.g., during the secondary separation process, described below). In one
embodiment, the
cement may be added to the oil sand ore-water slurry (or any derivative
thereof) before or
during any extraction process. As used herein, an "extraction" process may
include any
process step or stage that furthers the liberation, separation, or isolation
of bitumen from the
other components of the oil-water slurry or its derivatives.
[0033] In one embodiment, the cement may be added to the oil sand ore-water
slurry (or any derivative thereof) before or during a primary separation
process. As referred
to herein, the "primary separation process" is the first separation of bitumen
froth from solids
after the oil sands ore-water slurry is formed and conditioned. In exemplary
embodiments,
primary separation of the bitumen froth from the solids may be accomplished by
any known
process or apparatus. For example, at the end of the slurry hydrotransport
pipeline, the
conditioned slurry may be discharged to one or more large stationary particle
separation cells
(PSC) or vessels. In the PSC, the aerated bitumen may float through the slurry
upwards to
the top of the cell where it may overflow, and be collected as primary bitumen
froth. Within
the PSC, the coarse solids may settle, forming a dense slurry at the bottom of
the PSC which
can be removed from the bottom of the PSC as "tailings" stream. Within the
PSC, fine solids
with some un-aerated fugitive fine bitumen droplets may remain suspended in
the slurry.
This low-density slurry may be removed from the middle of the separation cell
as a
"middlings" stream. In various embodiments, the cement process aid may be
added before or
during any of the primary separation stages described herein, or their
respective equivalents.
For example, the cement process aid may be added to the oil sand ore-water
slurry in the
PSC.
[0034] In exemplary embodiments, one or more of the streams from the primary
separation processes may optionally undergo further processing to further the
bitumen
separation and isolation from the other components of the streams. These
processes are
referred to as "secondary separation processes." In exemplary embodiments, the
cement may
be added to the slurry or any derivative thereof in a secondary separation
process. For
example, the middlings stream may be further processed using flotation
technology to
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enhance bitumen-air attachment. An exemplary flotation technology may be, for
example,
mechanical flotation process or a flotation column in which air is added to
enhance bitumen-
air attachment. In this flotation process, middlings may be subjected to
vigorous agitation
and aeration, and the aerated fine bitumen droplets may be recovered as
secondary bitumen
froth. The secondary bitumen froth may be returned to the PSC for further
cleaning or sent
with the primary bitumen froth from PSC to a subsequent bitumen froth cleaning
stage. In
exemplary embodiments, the tailings stream from the PSC may be further
processed, for
example, in a tailings oil recovery (TOR) unit. The TOR may include a
secondary separation
cell or a flotation cells for further recovery of bitumen from the tailing
stream. In the
secondary separation processes, additional air or water may be added to the
process streams
to further enhance the separation or isolation of bitumen. In the embodiments,
cement may
be added to the slurry or process streams thereof to further enhance the
separation or isolation
of bitumen from these streams.
[0035] In exemplary embodiments, the streams from separation processes may
optionally undergo additional processing to further the bitumen separation and
isolation. For
example, the primary separation process and/or the secondary separation
process, or any of
the steps related thereto may be repeated in order to achieve the necessary or
desired result.
In the exemplary embodiments, the cement process aid may be used in these
additional
processing steps to further the bitumen separation and isolation.
[0036] In certain embodiments, the cement can be used to replace some or all
of the
sodium hydroxide or other process aid chemicals in a process for recovering
bitumen from oil
sands ore. In one embodiment, the process does not comprise the addition of
any sodium
hydroxide or other process aid chemicals other than cement.
[0037] In the exemplary embodiments, the cement material may be added to the
oil
sands slurries as a dry powder or as a suspension in water.
[0038] In exemplary embodiments, the cement may be added to the oil sands ore-
water slurry (or any process streams derived therefrom) in any amount to
provide a necessary
or desired result. For example, the dosage of cement may be the amount
effective to provide
the maximum yield of bitumen at that point in the process. In exemplary
embodiments the
cement may be added in a broad range of cement dosages without adversely
impacting
bitumen extraction or release water chemistry. In exemplary embodiments, the
cement
dosage may be that which is effective to reduce the attraction between clay
particles and
bitumen, thereby promoting the detachment of clay particles from bitumen
droplets in an oil
sands ore-water slurry. In exemplary embodiments, the dosage of cement process
aid is any
amount sufficient to raise the pH of the slurry or stream to about 6 to about
12, or about 8 to
about 11, or about 8.5 to about 10.
[0039] In one embodiment, the dosage of cement added to the oil sands ore-
water
slurry or process streams derived therefrom is in the range of about 10 to
about 10000 grams
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cement per dry ton (g/t) of ore (e.g., for the slurry) or of dry suspended
solids (e.g., for other
process streams). In some embodiments, the dosage is from about 100 to about
5000 g/t,
about 100 to about 2000 g/t, about 50 to about 1700 g/t, about 100 to about
1600 g/t, about
500 to about 1150 g/t, or about 500 to about 1000 g/t. In one embodiment, the
dosage of
cement is about 300 g/t, about 350 g/t, about 400 g/t, about 450 g/t, about
500 g/t, about 550
git, about 600 g/t, about 650 g/t, about 700 g/t, about 750 g/t, about 800
g/t, about 850 g/t,
about 900 g/t, about 950 g/t, about 1000 g/t, about 1050 g/t, about 1100 g/t,
about 1150 g/t,
about 1200 g/t, about 1250 g/t, about 1300 g/t, about 1350 g/t, about 1400
g/t, about 1450 g/t,
about 1500 g/t, about 1550 g/t, or about 1600 g/t.
[0040] In one embodiment, after addition of the cement, the cement is
permitted to
remain in contact with the oil sands ore-water slurry (or process streams
derived therefrom)
for a predetermined amount of time prior to separation of the bitumen. In some
embodiments, the cement remains in contact with the oil-water slurry or a
process stream for
about 10 minutes to about 180 minutes, about 15 minutes to about 120 minutes,
about 20
minutes to about 90 minutes, or about 20 minutes to about 60 minutes prior to
the separation
of the bitumen.
[0041] In certain embodiments, the processes may recover at least about 5%,
about
10%, about 20%, about 30%, about 40%, or about 50% more bitumen than
comparable
processes using sodium hydroxide or lime.
[0042] In one embodiment, at least about 60%, about 65%, about 70%, about 75%,
about 80%, about 85%, about 90%, about 95% of the total organic compounds or
bitumen are
extracted in the primary and secondary separation steps of the processes
described herein.
[0043] In any of the foregoing embodiments, the slurry (or process streams
derived
therefrom) may further include any additive or other process aid, such as a
surfactant, an anti-
foaming agent, a polymer, a flocculent, a mineral oil or a mixture thereof In
one
embodiment, the additives are in an amount of 0.01 to 10 weight percent based
on the total
weight of the composition.
[0044] The following examples are presented for illustrative purposes only,
and are
not intended to be limiting.
EXAMPLES
[0045] Testing Methods
[0046] The experiments were conducted in a laboratory scale Denver flotation
cell
(Metso Minerals, Danville, PA) under semi-batch conditions (batch water,
continuous air). In
a typical experiment, 300 g of oil sand ore was added to 1.5 1 pre-heated
water at 50 C at the
impeller speed of 1000 rpm in a 2 1 rectangular cell. The flotation cell was
kept at 50 C by
using a hot water circulating bath. The pH of water/slurry was adjusted to 8.5
or by addition
of sodium hydroxide or cement prior to addition of ore and the pH was
monitored during the
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flotation process. The slurry was conditioned for 5 min. The slurry was then
subjected to air
bubble flotation using an airflow rate of 200 ml/min Froths were collected at
time intervals of
2, 5, 10, 20 and 60 after flotation while agitation was paused for 30 sec.
Bitumen recovery
rates, solid and water contents were determined from solvent extraction on
standard Soxhlet
extractor units using toluene solvent. The experiments were run in triplicate
experiments,
with recovery rates being reproducible within +5%.
[0047] Compositions of Oil Sands Samples
[0048] Samples of low and high grade Athabasca oil sands were obtained from
Alberta Innovates Technology Futures, oil sands sample bank (Edmonton,
Canada). The
general composition of oil sands ores used in the examples is shown in Table
1.
[0049] Table 1
High Grade Oil Sands Low Grade Ore Sands
HG1 HG2 HG3 LG1 LG2 LG3
Bitumen A 12.56 12.40 12.35 8.09 6.06 7.32
Water % 3.77 6.00 5.24 3.35 9.44 6.57
Solids % 83.67 81.60 82.41 88.56 84.50 86.11
[0050] Compositions of Cements
[0051] APT cements class A and G were obtained from Lehigh Cement Company
(Edmonton, Canada). ReezCEM 800TM is a microfine blend of Class A cement and
pozzolanic materials with particle size less than 15 um available from Pontis
Energy Inc
(Calgary, Canada). Bulk chemical composition by XRF analysis of cement samples
used in
the examples are given in Table 2.
[0052] Table 2
Cement A Cement G ReezCEM 800
CaO 65.4 65.9 62.9
5i02 17.9 16.7 19.3
Fe2O3 4.76 5.90 3.18
SO3 4.27 4.14 5.55
A1203 3.10 2.78 3.89
MgO 2.23 1.83 2.61
K20 0.676 0.836 0.831
Na2O 0.477 0.441 0.250
CuO 0.179 0.211 0.165
TiO2 0.183 0.191 0.266
BaO 0.151 0.082 0.192
ZnO 0.111 0.121 0.131
Sr0 0.108 0.104 0.075
13205 0.085 0.113 0.139
[0053] Example 1. Comparison of Bitumen Recovery from High Grade Oil
Sands
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[0054] In this example, bitumen was recovered from high grade oil sand ores
using
sodium hydroxide and API class A cement process aids. In these experiments,
the pH of
water was adjusted to 8.5 using NaOH or cement before the flotation process.
As shown in
Table 3, bitumen recovery in the presence of Portland cement resulted in
higher bitumen
recoveries than bitumen recovery in the presence of NaOH. Furthermore, the
conditions for
these improved recovery rates did not change the water chemistry with respect
to the
concentration of mono- and divalent cations.
[0055] Table 3
Sample Treated Bitumen Bitumen/Solid Bitumen/Water [Na] [Ca2] [Mg2]
ID by Recovery A Ratio Ratio PPm PPm PPm
HG1 NaOH 91.56 2.94 0.41 47 0.6 0.1
Cem A 94.05 2.46 0.30 47 0.6 0.1
HG2 NaOH 94.37 2.09 0.23 20 5.2 18
Cem A 95.41 2.13 0.22 18 4.6 16
HG3 NaOH 90.62 2.61 0.34 25 7.6 8.3
Cem A 92.29 2.54 0.37 30 10 9.7
Cem A = API class A cement
[0056] Example 2. Comparison of Bitumen Recovery from Low Grade Oil
Sands
[0057] In this example, bitumen was recovered from low grade oil sand ores,
using
sodium hydroxide and API class A cement process aids. In these experiments,
the pH of
water was adjusted to 8.5 using NaOH or cement before the flotation process.
As shown in
Table 4, bitumen recovery in the presence of Portland cement resulted in
higher bitumen
recoveries than bitumen recovery in the presence of NaOH. Furthermore, the
conditions for
these improved recovery rates did not change the water chemistry with respect
to the
concentration of mono- and divalent cations.
[0058] Table 4
Sample Treated Bitumen Bitumen/Solid Bitumen/Water [Nal [Ca2+] [Mg2]
ID by Recovery % Ratio Ratio PPm PPm PPm
LG1 NaOH 59.41 1.00 0.13 17 22 16
Cem A 60.68 0.77 0.10 13 20 14
LG2 NaOH 64.19 0.68 0.09 19 50 18
Cem A 90.71 0.97 0.15 15 47 15
LG3 NaOH 71.28 1.28 0.30 40 0.1 0.1
Cem A 82.69 1.28 0.30 43 0.1 0.1
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Cem A = API Class A cement
[0059] Figure 1 shows the bitumen recovery data as a function of time for low
grade ore sample LG2 treated by NaOH and API Class A cement (Cem A). As shown
in
Figure 1, the use of Portland cement improves the liberation of bitumen from
sand. For this
LG2 sample, more than 70% of bitumen is liberated within 20 min of flotation
compared to
only 50% when NaOH was used.
[0060] Example 3. Effect of Dosage of Portland Cement on Bitumen Recovery
Rate
[0061] In this example, the effect of dosage of Portland cement on bitumen
recovery rate was examined in an experiment using 100 - 1600 git of API Class
A Portland
cement on low grade oil sand sample LG3. Data are summarized in Table 5 and
graphically
represented in Figure 2. The results show that Portland cement can be used as
an effective
process aid at a wide range of dosages, and that the dosage of 750 g/t gave
the maximum
recovery rate of 90%.
[0062] Table 5
100 g/t 500 g/t 750 g/t 1150 g/t
1600 g/t
pH (initial) 9.00 9.82 9.96 10.14 10.33
pH (final) 7.73 8.50 8.89 9.41 9.82
Bitumen Recovery % 65.51 84.95 90.80 78.59 69.95
Bitumen/Solid Ratio 1.07 0.88 0.83 0.73 0.66
Bitumen/Water Ratio 0.25 0.26 0.23 0.21 0.14
Processed Water Analysis
[Nat] in ppm 44 44 48 49 47
[Ca2+ ] in ppm 0.1 1.4 7.2 5.2 5.0
[mg2+] in ppm
0.1 0.1 0.1 0.1 0.1
[0063] Example 4. Effect of pH on Bitumen Recovery Rates
[0064] In this example, the effect of dosage on bitumen recovery rate was
examined in an experiment wherein the pH of water/slurry was adjusted to 8.5
or 10 by
addition of sodium hydroxide or Portland cement prior to addition of ore and
monitored
during the flotation process. As shown in Table 6, Portland cement at both pH
8.5 and 10
results in higher recovery rate when compared to pH adjustments using sodium
hydroxide. It
was also noted that Portland cement increased bitumen recovery from pH 8.5 to
10, while
under the same conditions bitumen recovery was reduced when sodium hydroxide
was used.
This is graphically represented in Figure 3.
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[0065] Table 6
Froth Froth Froth Froth Froth [Nal [Ca21 [Mg2]
No. 1 No. 2 No. 3 No. 4 No. 5 PPm PPm PPm
NaOH (pH 8.5) 13.62% 27.39% 40.44% 54.63% 71.28% 40 0.1
0.1
NaOH (pH 15.10% 24.92% 35.61% 44.96% 58.70% 68 0.1
0.1
10.0)
Cem A (pH 15.84% 31.10% 47.30% 63.95% 82.69% 43 0.1
0.1
8.5)
Cem A (pH 18.58% 39.14% 59.41% 75.51% 90.80% 48 7.2
0.1
10.0)
[0066] Example 5. Effect of the Type of Portland Cement on Bitumen
Recovery
[0067] In this example, the effect of the type of Portland cement on bitumen
recovery from oil sand ores was assessed. Class A and G cements as well as a
microfine
cement, ReezCEMTm, were utilized on a low grade oil sand sample of LG3. Data
are
summarized in Table 7. It was found that all types of Portland cement could be
used as a
process aid in bitumen recovery from oil sand ores.
[0068] Table 7
Treated by Bitumen Bitumen/Solid Bitumen/Water [Na] ICa2+]
[Mg2]
Recovery A) Ratio Ratio PPm PPm PPm
Cem A 82.69 1.28 0.30 43 0.1 0.1
Cem G 73.95 1.20 0.28 43 0.1 0.1
ReezCEM 78.52 1.16 0.28 41 0.1 0.1
[0069] Example 6. Effect of Using Recycled Water From A Portland Cement
Process
[0070] In this example, the use of recycled water from process comprising
Portland
cement was also examined. In this study, the process water was used after
filtration for
bitumen recovery using flotation. The pH of water was initially adjusted to
8.5 using Portland
cement and a low grade ore sand sample from LG3 was used. As shown in Table 8,
bitumen
recoveries did not change within 5 cycles of water reuse, and no significant
change in water
chemistry was observed.
[0071] Table 8
Cycle 1 Cycle 2 Cycle 3 Cycle 4 Cycle 5
Cement added (g/ t) 51 49 63 93 87
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Bitumen Recovery % 66.10 64.25 69.05 71.36 76.48
Bitumen/Solid Ratio 1.12 1.34 1.29 1.08 1.06
Bitumen/Water Ratio 0.26 0.32 0.34 0.36 0.37
pH (initial) 8.64 8.55 8.50 8.54 8.58
pH (final) 7.53 7.66 7.72 7.81 7.86
Processed Water Analysis:
[Na] in ppm 47 59 38 74 77
[Ca2+ ] in ppm 0.1 0.1 0.1 0.1 0.6
[m82-] in ppm
0.1 0.7 0.1 0.1 0.1
14
