Note: Descriptions are shown in the official language in which they were submitted.
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Composition for Recovering Bitumen from Oil Sands
Cross-reference to Prior Applications
[0001] Not applicable.
U.S. Government Support
[0002] Not applicable.
Background
Area of the Art
[0003] [AREA OF ART]
Description of the Background
[0004] Almost all of the energy used on our planet come ultimately from the
Sun. Fossil
fuels represent the photosynthetic products of long-dead photosynthetic
organisms.
Generally, fossils of macroscopic terrestrial organisms yield materials that
range from
peats to coals. Generally, microscopic marine and freshwater aquatic
photosynthetic
organisms have left us with "oil" or, more properly, petroleum. When aquatic
photosynthetic organisms ("algae" and "zooplankton") die and are entrapped in
sediments, the organic matter is modified by heat and pressure and the
resulting organic
fluids migrate and become trapped by overlying geological structures to form
"oil
reservoirs" which can be tapped to form oil wells. However, large amounts of
aquatic
organic matter become deposited with clay minerals or with sand grains to form
organically rich sandstone or shale. When the conditions are such that the
organic matter
is unable to migrate one is left with oil sand, tar sand or even oil shale.
The organic matter
can be extracted from these material as "unconventional" petroleum.
[0005] Many of the largest unconventional petroleum deposits actually contain
a carbon-
rich substance known as "bitumen" or tar. The term "bitumen" includes a
variety of
viscous or solid mixtures of hydrocarbons that occur naturally as asphalt,
tar, mineral
waxes, and the like. Bitumen can be thought of as petroleum from which most of
the
volatile components have been driven off over time. Bitumen deposits can be
found in
many parts of the world and, where they occur in admixture with sand or clay,
such
deposits are often referred to as bituminous sands, oil sands or tar sands
(hereinafter
referred to as "oil sands"). The majority of all the known oil in the world is
contained in ore
primarily oil sands. Large deposits of bituminous sands are present in Canada,
the USA,
Venezuela and Africa. Canada's oil sands are currently being exploited
commercially on a
large scale. Because the deposits lie at or close to the surface of the ground
in the major
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Canadian locations (Athabasca oil sands), the bituminous ore can be strip-
mined and
transported to a central facility for treatment. Although modern refinery
processes allow
bitumen to be converted into mixtures of more fluid hydrocarbons (and other
petrochemicals), the bitumen, which is extremely dense and viscous, must first
be
separated from the solid portions of the ore (primarily sand and clay) as well
as from
water added during the mining and transportation processes. The environmental
problems currently attributed to oil sand mining are largely related to these
removed
byproducts.
[0006] Oil sand, as mined commercially, contains an average of 10-12% bitumen,
83-
85% mineral matter and 4-6% water. Today, all of the producers doing surface
mining,
such as Syncrude Canada, Suncor Energy and Albian Sands Energy etc., use a
variation
of the Clark Hot Water Extraction (CHWE) process. It is possible to think of
this process
as involving Heat, Air and High pH to remove bitumen from the solids (sand,
etc.). The
application of heat lowers the viscosity (i.e. melts) of the bitumen so that
some of it can
detach from the solids. The addition of air provides bubbles that help float
the dense
bitumen to form a froth. Not only do the air bubbles act as "life jackets" to
float the
bitumen, the bubbles represent hydrophobic surfaces so that the bitumen is
able to
transfer from the solid (sand) surface to the bubble surface. Increasing the
pH improves
the floatation and separation process. To some extent this effect is believed
to result from
the neutralization and saponification of organic acids, etc. in the bitumen to
form natural
surfactants.
[0007] In the CHWE process, the ores are mined using open-pit mining
technology. The
mined ore is then crushed for size reduction. A film of water coats most of
the mineral
matter, and this property permits extraction by the hot-water process. The oil
sand is put
into massive rotating drums and slurried with hot water at 50-80 C water and
some
steam. The formed slurry is often transported using a "hydro transport"
pipeline which
includes mixing the ore with warm water at high pH at the mine and pumping it
by pipeline
to the extraction plant. During the transport to the plant, the bituminous ore
is conditioned,
causing complex physical and chemical changes to occur that break the surface
tension
between hydrocarbon and water components. Bitumen itself contains naturally
occurring
water-soluble organic acids and surfactants, but these do not become fully
active until the
pH and temperature conditions are sufficiently high. Sodium hydroxide (NaOH or
caustic
soda) or other basic chemicals such as potassium hydroxide are added to raise
the pH.
Under these conditions, the bitumen begins to liquefy and detach from the
mineral
particles. Conditioned slurry is passed through a screen to remove rocks and
large
pebbles. At the extraction plant a primary separation vessel (PSV), a large,
conical
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separation vessel, is used to recover bitumen by flotation as bitumen froth
which floats to
the top while coarse sand settles and is pumped to disposal sites. The froth
of bitumen is
skimmed from the top of the PSV and generally consists of about 60%-65%
bitumen,
25%-30% water and about10% solids by weight.
[0008] The initial separation is known as primary extraction and the froth is
known as
"primary froth." After the primary froth is harvested, additional mixing and
addition of air
(secondary extraction) produces a "secondary froth" from the bitumen still
suspended in
the water (known as "middlings"). The primary and secondary extraction yield
at least
80% of the bitumen in the ore. The remaining bitumen remains suspended in the
water or
adheres to the solids. A portion of that bitumen can be recovered by various
secondary
treatments. Generally, 88-95% (in some cases as much as 100%) of the bitumen
in the
mined ore is recovered.
[0009] Coarse sand from the primary separators is used to build dikes, forming
the large
tailings ponds needed to contain the effluent. In these ponds the fine
particles settle
slowly, producing clarified water that is reused in the extraction process.
The fine particles
do not consolidate to their original density, so every cubic meter of oil sand
mined creates
about 1.4 cubic meters of material for disposal. Removal of the contaminants
from the
froth stream is achieved through dilution with naphtha followed by two stages
of
centrifugation. The industry has recently installed inclined-plate gravity
settlers in series
with the centrifuges. About 98% of the bitumen in the froth is recovered. The
water needs
of a large project like that of Syncrude are substantial, amounting to about
0.4% of the
average flow of the Athabasca River. After removal of residual water and fine
solids, the
bitumen is mixed with lighter petroleum-based solvents or chemically "cracked"
so that it
can be transported by pipeline as "synthetic crude oil" for subsequent
refining into a
variety of hydrocarbon products. After oil extraction, the spent sand and
other materials
are then returned to the mine, which is eventually reclaimed.
[0010] A main disadvantage of this conventional extraction procedure is the
large
amounts of energy that are required for heating the hot water used for bitumen
separation
from the ore. A further disadvantage is that the caustic soda employed in the
process is
toxic and corrosive and requires careful and expensive regeneration or
disposal
procedures. The energy required for the hot water process is produced by
burning
hydrocarbons and results in the production of large amounts of carbon dioxide.
This
greatly increases the amount of greenhouse gases attributable to oil sands
even before
refining and use as conventional motor fuels. In addition, the large volume of
water used
for processing becomes contaminated by the added sodium hydroxide and soluble
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organic and inorganic components extracted from the bitumen. This necessitates
complex processing to reclaim the water and isolate the local environment from
harm.
[0011] There is consequently a great need for improved processes that overcome
or at
least reduce these problems. Up until now these attempts at improved processes
have
generally involved the addition of solvents and surfactants. Because bitumen
is heavy
(i.e., dense) and extremely viscous, it is generally known that added solvents
can
decrease the viscosity and density of the bitumen so that it can flow and
float on water
with or without an "air bubble assist." Hopefully, additional solvents would
achieve this
without requiring high temperatures. Similarly, surfactants ("wetting agents")
help detach
the bitumen from the mineral particles and suspend the bitumen as an emulsion
until the
mineral particles settle out gravitationally. An example of this approach is
found in
Published U.S. Patent Application 2008/0169222 which discloses an improved tar
sand
process invented by Kevin Ophus.
[0012] The Ophus process uses an emulsion of the organic solvent d-limonene to
separate the bitumen from the sand particles. The emulsion is prepared by
mixing about
40% D-limonene and about 60% water (in the form of a weak sodium bicarbonate
solution) with about 0.2% anionic surfactant and a trace amount of an anti-
foaming agent.
Vigorous mixing produces an emulsion having the color and consistency of dairy
cream.
A quantity of this emulsion is added to an aqueous slurry of tar sand where is
helps the
bitumen separate from the sand. Charts and tables in this application show
that for the
process to obtain an 80% bitumen recovery, the solvent content of the slurry
must be at
least about 5% and the temperature must be at least 30 C. At higher
temperatures
and/or higher solvent concentrations recovery is above 80%, and at lower
temperatures
and lower solvent concentrations recovery is below 80%. The Ophus process
partially
solves the disadvantages of the prior art Clark process by lowering the amount
of energy
used to heat the water and by largely eliminating the use of sodium hydroxide.
However,
this comes as the expense of introducing a considerable amount of organic
solvent (d-
limonene) and into the process. To the extent that this solvent dissolves into
the bitumen,
it can be recovered and recycled by distillation; however, there is a
considerable energy
cost in such recovery. To the extent that the solvent enters the waste stream,
it is
considered to be of low toxicity although it has some potential as an
irritant. D-limonene is
slowly biodegradable. Surfactants used are also biodegradable. Apart from the
cost of the
d-limonene, the main cost of the Ophus process seems to be that of the energy
to heat
the water.
[0013] The conventional process has not yet been superseded by improved
technology
and continues to be plagued by a number of environmental problems. First is
energy
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usage. Conventional procedures require large amounts of energy for heating the
hot
water used for bitumen separation. This is currently provided primarily by
natural gas.
Obviously, this natural gas is not free. The requirement to heat the
extraction water
significantly increases the cost of the recovered bitumen.
[0014] Second is the problem of environmental pollution; the current
extraction process
requires huge amounts of natural gas for the heating water. As of 2007, the
Canadian oil
sands industry used about 4% of the Western Canada Sedimentary Basin natural
gas
production. By 2015, this may increase 2.5 fold particularly if key pipelines
are brought on
line. This burning of natural gas generates large amounts of carbon dioxide
and diverts
natural gas from electric power generation and other uses where it could
actually
moderate overall carbon dioxide production. The serious "greenhouse" effects
of gases
such as carbon dioxide on the world climate is well recognized.
[0015] An additional environmental problem is produced by the processing of
smaller
bitumen and mineral particles remaining in an intermediate water layer, called
middlings
which are pumped onto a separation vessel similar to the one mentioned above.
The
middlings are ultimately pumped to settling or tailing ponds and ultimately
return to the
local rivers. Pollutants enter the ecosystem creating numerous hazards for the
wildlife as
well as humans. Studies have shown that hundreds to thousands of birds each
year die
due to the effects of tailing ponds. Many birds migrating across the country
landing in
waters to rest, and toxic components in the water can lead to an 80-90% death
rate.
There has also been a large impact on the fish that live and spawn in the
area. As toxins
accumulate in the rivers due to the refining process, bizarre mutations,
tumors and
deformed fish species have begun to appear. A study commissioned by the
regions
health authority, found that several known toxins and carcinogens were
elevated.
Aboriginal communities that live around the river are becoming increasingly
worried about
how the animals they eat and their drinking water are being affected.
Summary of the Invention
[0016] An exemplary embodiment of the invention relates to a two part
composition
useful for extracting bitumen from bituminous sand ores (oil sands). This
combination is
particularly useful for extracting bitumen from high grade 10% to 14%
bituminous sand
ores as a full or partial replacement for the conventional hot water/caustic
soda process.
Typically, the combination recovers 80% of the bitumen using a small amount of
the
composition and at temperatures no greater than 35 C. The basic rate of
recovery can be
increased by increasing the temperature and/or the amount of composition
employed.
Cost benefit analysis can be used to select the optimum combination of
temperature and
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volume of composition. The composition can be used directly in existing
extraction
equipment. It is likely that specially designed equipment could yield even
better
recoveries.
[0017] When used directly in existing PSVs the two part composition
particularly
enhances the secondary froth recovery rate. Another use for the invention
relates to a
process of extracting bitumen from lower grade 6% to 8% bituminous sand ores.
Another
embodiment of the present invention relates to the extraction of residual
concentrations of
Total Petroleum Hydrocarbons (TPH) from the tailing ponds. The inventive
compositions
are unique in that they release the bitumen from the sand and keep it in an
emulsified
state for ease in transport. Thereafter, an additional stage is applied to
float the bitumen
for ease in recovery. The composition can be easily manipulated to a range
sufficient to
extract bitumen from a variety of ore.
[0018] The two part composition comprises in the first part a solvent mixture
containing
an environmentally safe monoterpene solvent, a non-ionic surfactant, a short
chain
alcohol and a short chain ketone. The preferred monoterpene solvent is a
biodegradable
cyclic terpene such as D-limonene. The second part of the combination is an
aqueous
solution of a pH builder such as sodium or potassium carbonate, sodium or
potassium
hydroxide or sodium or potassium silicate. In use in existing equipment for
primary
bitumen recovery a small quantity of the solvent mixture is added to the ore
and mixed
thoroughly. Following that a larger volume of the aqueous pH builder is added
and mixing
is continued. Finally, a large volume of water is added with continued mixing
in a PSV.
When mixing stops, the primary froth separates from the ore and water and is
harvested.
Mixing then is continued along with addition of air and the secondary froth
separates and
is harvested. Unlike the traditional caustic soda process, the pH of the
middlings is below
pH 9Ø The middlings and the tailing are then subjected to enhanced secondary
recovery
processing which may include use of an embodiment of the present invention to
release
additional bitumen from the ore and middlings.
[0019] Depending on the precise application the various ingredients of the
solvent
mixture are included in different amounts. Preferably, these ingredients are
present in the
following proportions (by volume) selected to make 100%:
Ingredient Parts by Volume
Terpene 7% to 40%
Non-Ionic Surfactant 15% to 45%
Short Chain Ketone 5% to 15%
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Short Chain Alcohol 25% to 45%
[0020] The solvent mixture may also contain one or more other solvents or
diluents, but
the primary ingredients listed above should preferably comprise at least 90%
by volume
of the composition.
[0021] The solvent mixture is a combination of surfactants and solvents
designed to
affect the surface tension of the bitumen in bituminous sand ores to
facilitate the
separation of the bitumen from the other materials present. The composition
also helps to
liquefy the bitumen and to maintain the bitumen in a suspended form to
facilitate the
separation process. Following an initial interaction of the mixture with
bitumen ore a pH
builder such as sodium carbonate is added. The pH builder enhances the
emulsification
of bitumen and promotes frothing and flotation of the bitumen.
[0022] The composition can be used to extract bitumen from its ore at
essentially
ambient temperature (e.g. 10 to 35 C), but it can be heated to higher
temperatures, but
still generally below those used for the conventional hot water process.
Energy
requirements can therefore be reduced considerably without substantial
reduction of
extraction yields. Under certain conditions, the exemplary forms of the
composition may
increase the yield of extracted bitumen as compared to conventional processes.
[0023] The main ingredients of the composition are compounds that are known to
be
safe and non-toxic and so that the spent composition can be disposed of
without
procedures required for the disposal of hazardous chemicals.
[0024] The composition may be used in much the same way as the conventional
process
for extraction of bitumen. That is to say, the mined oil sands ore is mixed
and agitated
with the composition to form an aqueous phase and a hydrocarbon phase, the
hydrocarbon phase is allowed to rise to the top of the mixture, and the
hydrocarbon phase
is then harvested.
[0025] The composition, at least in its preferred forms, can therefore have
the following
advantages:
1) It can improve the recovery yield of bitumen and saleable synthetic crude
oil
equal to or above the present level;
2) It can improve thermodynamic efficiency and reduce the amount of heat
required
in bitumen extraction operations; and
3) It can reduce, or remove and eliminate, environmental impact.
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4) The composition does not affect the total petroleum hydrocarbon (TPH)
concentrations of the bitumen.
Description of the Figures
[0026] FIGURE 1 shows Bitumen Recovery Units comparing the invention with
prior art
methods.
Detailed Description of the Invention
[0027] The following description is provided to enable any person skilled in
the art to
make and use the invention and sets forth the best modes contemplated by the
inventor
of carrying out his invention. Various modifications, however, will remain
readily apparent
to those skilled in the art, since the general principles of the present
invention have been
defined herein specifically to provide an improved and environmentally safe
composition
for recovering bitumen from oil sands.
[0028] As used herein, the term "about" means "approximately," and, in any
event, may
indicate as much as a 10% deviation from the number being modified.
[0029] Process As explained in more detail below the current composition is
directly
useable in the current CHWE process. However, it somewhat modifies the way in
which
the process attains its results. The most apparent differences and advantages
are the
need for much lower amounts of energy because the water temperature is much
lower
and the use of environmentally safe additives so that the effluents from the
process are
harmless.
[0030] The process conceptually consists of four phases which are
interdigitated into the
CHWE process steps. In the first two phases, Phase I (extraction ) and Phase
II
(separation) ¨ an organic terpenoids solvent such as D-limonene is used to
extract the
organic compounds. Because the preferred terpenes are non-soluble in water a
surfactant is used to decrease the surface tension of water to emulsify the
terpene or
even make it soluble both in water and in the organic (bitumen) phase. The
large bitumen
hydrocarbons are extracted by the terpene and surfactant thus freeing them
from their
bond to the sand. Also, when the terpene dissolves into the bitumen, it
decreases both
bitumen viscosity and density. The terpene will not extract/interact with all
the organic
compounds (particularly the low molecular weight and more hydrophilic
compounds) in
the bitumen. The alcohol and acetone extract and suspend the rest of the
organic
compound that are not extracted by the surfactant/terpene. Alcohol and acetone
have a
high affinity for small organic compounds therefore they continue to extract
and separate
the smaller organic hydrocarbons from the sand. The addition of the sodium
carbonate
pH builder acts to make the organic compounds more soluble in the organic
phase
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because the amount of base added is not sufficient to saponify them as in the
CHWE
process. As a result the aqueous phase is not above pH 8 (i.e., fairly close
to neutrality).
[0031] In the next two phases Phase III (blocking) and Phase IV (suspension)
the
alcohol and acetone as well as the pH builder keep the smaller molecules in
suspension
and keep them from reattaching themselves to the solids. The use of acetone
and alcohol
also decreases the boiling point needed separate the organics thus decreasing
the
heating requirements during the extraction and separation phase of the
bitumen. The final
product has a neutral pH and no toxic compounds have been added. The terpene,
surfactant, alcohol and acetone are readily biodegradable.
[0032] Ingredients As indicated, the present invention is a two component
system for low
temperature extraction of bitumen from oil sands. The first component is a
solvent
component and the second component is a pH building component. The solvent
component comprises a monoterpene such as citral, citronella!, citronellol,
limonene or
linalool; the preferred terpene being the cyclic terpene D-limonene; a short
chain alcohol,
a short chain ketone and a non-ionic surfactant. The purpose of the solvent
component is
to dissolve into the bitumen and to loosen it from the sand and other solid
material and
help suspend it in an emulsion. The alcohol and ketone are relatively
hydrophilic and
interact with the hydrophilic moiety of the surfactant to emulsify and suspend
the more
organic hydrophobic components and/or to directly solvate them. Isopropyl and
propyl
alcohol are the preferred short chain alcohols although alcohols having
between 2 and 5
carbons and ketones having 3-6 carbons (such as 2-butanone) are within the
usable
range. Acetone is the preferred ketone. The terpene is relatively hydrophobic
and
interacts/dissolves into the bitumen and interacts with the hydrophobic moiety
of the
surfactant.
[0033] Surfactants are amphiphilic organic compounds that have both
hydrophobic and
hydrophilic groups so that one end of the molecule is soluble in hydrophobic
compounds
such as bitumen and limonene while another part of the molecule is soluble in
water and
water miscible compounds such as isopropyl alcohol. As such they generally
lower the
surface tension of water and emulsify hydrophilic and hydrophobic compounds.
In a
typical oil in water emulsion (where hydrophilic particles are embedded in an
aqueous
milieu) The hydrophobic ends of the surfactant molecule are dissolved into the
oil
particles so that the surface of each particle is essentially covered by
hydrophilic groups
(the other ends of the surfactant molecules) which help the particles interact
with and
remain suspended in the water. Depending on the type of hydrophilic group
present on
the surfactant molecule, the surfactant may have a negative charge (an anionic
surfactant), a positive charge (a cationic surfactant) or a neutral charge (a
nonionic
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surfactant). The present invention generally employs anionic surfactants.
Depending on
the nature of the hydrophobic and hydrophilic groups a given surfactant may be
generally
hydrophilic or generally hydrophobic. This is known as the HLB or hydrophilic-
lipophilic
balance of the surfactant. The HLB scale runs from 0 to 20 with surfactants
with an HLB
number below about 10 being so hydrophobic that they are primarily lipid
soluble while
those with an HLB of greater than 10 are primarily water soluble. Surfactants
having an
HLB value in the range of about 7-11 act as emulsifiers that produce stable
water in oil
emulsions while those having an HLB value in the range of about 12-16 act as
emulsifiers
that produce stable oil in water emulsions. Surfactants having very high HLB
values (e.g.
16-20) act as hydrotropes which are capable of solubilizing hydrophobic
materials without
forming micelles or small particles of the hydrophobic substance. It will be
apparent that
the preferred surfactants with be in the HLB range of 12-16 because bitumen is
emulsified
into water and then floated free to be recovered as a froth. Currently,
ethcmlated/propoxylated alcohol- nonylphenol surfactants (such as TERGITOL NP-
6 and
NP-7 or NEXEO Surfactant 579 (Nexeo Solutions)) or ethoxylated/propoxylated
branched
alcohols (such as TRITO XL-80N) are preferred. A preferred single surfactant
has an HLB
of between 11 and 12. Addition of a quantity of lower HLB surfactant may
encourage the
bitumen particles to coalesce and allow separation particularly in a secondary
recovery
situation. Different surfactants can be combined to obtain an ideal HLB value.
An ideal
surfactant blend would create an HLB value between 12 and 16. In some
situations
addition of hydrotropic surfactant may aid in the initial separation of the
bitumen from the
solid mineral portion of the ore.
[0034] The preferred surfactants are nonionic although a small quantity of an
anionic
hydrotrope may be included in combination with the anionic surfactant(s). The
surfactant
may include one or more ethoxylated acetylenic alcohols, such as, for example,
2,5,8,11-
tetramethy1-6-dodecyn-5,8-diol ethoxylate. In most cases, the ethoxysulfate
analog of the
ethoxylated can be substitute. Suitable non-ionic surfactants include, for
example,
DYNOL surfactants such as DYNOL 604, or 607 (Air Products and Chemicals,
Inc.);
SURFYNOL surfactants (Air Products and Chemicals, Inc.) such as SURFYNOL 420,
440, 465, and 485; TOMADOL surfactants (Tomah Products, Inc.) such as TOMADOL
1-3, 1-5, 1-7, 1-9, 1-73B, 2.5, 23-1, 23-3, 23-5, 23-6.5, 25-3, 25-7, 25-9, 25-
12, 45-7, 45-
13; 91-6 and 91-8,TERGITOL nonionic surfactants (Dow Chemical Company) such
as
TERGITOL MinFoam, L-61, L-64, L-81, L-101, NP-4, NP-6, NP-7, NP-8, NP-9, NP-
11,
NP-12, NP-13, NP-15, NP-30, and NP-40; TRITON surfactants (Dow Chemical
Company), such as TRITON X-15, X-35, X-45, X-100, X-114, X-165, X-305, X-405,
X-
207, BG and CA; NOVEC Fluorosurfactant FC-4434 (3M Company); POLYFOX AT-
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1118B (Omnova Solutions, Inc.); ZONYL surfactants (DuPont) such as ZONYL 210,
225, 321, 8740, 8834L, 8857A, 8952, 9027, 9338, 9360, 9361, 9582, 9671, FS-
300, FS-
500, FS-610, 1033D, FSE, FSK, FSH, FSJ, FSA, and FSN-100; LUTENSOL
surfactants
(BASF) such as LUTENSOL OP 30-70%, A 3 N, A 9 N, A 12 N, A 65 N, AO 3, AO 4,
AO
8, AT 25, AT 55, CF 10 90, DNP 10, NP 4, NP-6, NP 9, NP 10, NP-50, NP-70-70%,
NP-
100, ON 40, ON 60, OP-10, TDA 3, TDA 6, TDA 9, TDA 10, XL 40, XL 50, XL 60, XL
69,
XL 70, XL 79, XL 80, XL 89, XL 90, XL 99, XL 100, XL 140, XP 100, XP 140, XP
30 XP
40, XP 50, XP 60, XP 69, XP 70, XP 79, XP 80, XP 89, XP 90 and XP 99; MACOL
surfactants (BASF) such as MACOL 16, CSA 20 POLYETHER, LA 4, LA 12, LF 110 and
LF 125A; MAPHOS polyphosphate ester nonionic surfactants (BASF) such as MAPHOS
58, 60A, 66H, 8135 and M-60; MAZON 1651 surfactant (BASF); MAZOX LDA
Lauramine OXIDE (BASF); PLURAFAC surfactants (BASF) such as PLURAFAC AO8A,
B-26, B25-5, D25, LF 1200, LF 2210, LF 4030, LF 7000, RA-20, RA 30, RA 40, RCS
43,
RCS 48, S205LF, S305LF, S505LF, SLF-18, SLF-18B-45, SLF 37, SL-22, SL-42, SL
62,
SL 92, and L1220; PLURONIC surfactants (BASF) such as PLURONIC 10R5, 17R2,
17R4, 25R2, 25R4, 31R1, E38, F68 LF, E68, F77, E87, F88, F98, E108, E108 NF,
F127,
F127 NF, F127NF 500BHT, L10, L31, L92, L101, L121, N-3, P65, P84, P85, P103,
P105,
P123; TETRONIC surfactants (BASF) such as TETRONIC 304, 701, 901, 904, 908,
1107, 1301, 1304, 1307, 150R1. Mixtures of one of more of these surfactants
can be
used. Although nonionic surfactants are used almost exclusively, small
quantities of ionic
hydrotropic agents may be included. Suitable hydrotropic agents may include,
for
example, one or more of TRITON products (Dow Chemical Company) such as TRITON
H-66, H-55, QS-44 or XQS-20.
[0035] Soluble salts are added as pH builders to increase solubility of
organic
compounds in the organic phase and to help prevent reattachment of the
bitumen. The
preferred salts are sodium or potassium carbonate, silicate or hydroxide. The
amount of
pH builder added brings the extracted bitumen to near neutrality in pH. The
"middlings" or
effluent water is also near neutrality (e.g., below pH 8.0) unlike the high pH
caustic
effluents of the CHWE.
[0036] A laboratory test of a preferred embodiment of the present invention
was made
according to methods routinely used to test extraction of bitumen from oil
sands. The
method used is based on a paper "Batch Extraction Unit for Tar Sand Processing
Studies
by E.C. Sanford and F.A. Seyer of the Syncrude Canada Ltd., Research
Department,
Edmonton, Alberta, Canada which was a portion of the HENRY H. STORCH AWARD
SYMPOSIUM presented in Miami Beach, FL in the fall of 1978. The method
described in
this paper defined the Bitumen Extraction Unit by providing a laboratory
simulation of the
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.
commercial Clark extraction process. In this method a jacketed extraction cell
(stainless
steel pot) is maintained at a constant temperature (approximately 80 C in the
traditional
process). The cell is square to facilitate slurrying and agitation by air or
paddle stirring
without need for added baffles. Air is added through the impeller (paddle)
shaft, and the
container is of sufficient height to provide a quiescent zone for froth
accumulation.
Impeller speed is controlled by a variable speed motor and tachometer. The
cell has a
valve at its bottom to remove tailings. In testing with the traditional hot
water method,
about 1.5 L of distilled water is heater to about 90 C in a separate
container. A quantity of
oil sand is homogenized and an aliquot is subjected to a procedure to
determine bitumen,
solids and water content. A 500 g sample of the oil sand is weighed and 150 ml
of the
90 C water is added to the extraction cell. This water is stirred with the
impeller in its
lowest position until the water temperature is reduced to the jacket
temperature (here
80 C). The 500 g oil sand sample is added to the cell and the motor assembly
and
impeller are used to break up lumps with the impeller being left about 3/4 of
an inch above
the bottom. The impeller is then set to 600 rpm and the airflow is adjusted to
465 cc/min
and stirring is continued for 10 min. The airflow is stopped and 1 L of 80 C
water is
added and stirring is continued for 10 min. Mixing is then stopped and the
primary froth is
skimmed off the top of the cell with a special spatula. The remaining material
is mixed at
800 rpm with an airflow of about 232 cc/min for 5 min. The secondary froth is
then
collected. The froth samples are analyzed for bitumen, solid and water
content. Finally
solids and remaining water are drained from the cell; the cell is cleaned with
solvent and
the next sample is analyzed.
[0037] This same procedure (with slight modification described below) is
carried out to
test the inventive compositions except that test temperatures are lower than
80 C. As
explained briefly above, the inventive composition consists of two parts, a
solvent mixture
and a pH builder. For the following tests a preferred embodiment of the
solvent mixture
was used and the pH builder was sodium carbonate as a 20% solution. For the
tests the
temperature was set to 35 C. For the "control" 500g of tar sand (containing
about 9.6%
bitumen) was added to the cell along with 150mL of 35 C tap water. This
mixture was
stirred for 10 min (as described above). At that point a liter of 35 C tap
water was added
and the stirring continued for another 10 min. The primary froth was collected
and stirring
(800 rpm) and air addition were started again for 5 min. Thereafter, the
secondary froth
was collected.
[0038] The solvent composition for this test contained D-limonene (15-25%),
nonylphenol
ethoxylated surfactant with HLB of 11-12 (25-35%), acetone (5-15%) and
isopropyl
alcohol (35-45%). For the treatment, the steps were the same except that 1 mL
of the
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solvent component was added along with the 150 mL of water for the initial
stirring. The
40 mL of pH builder (20% sodium carbonate) was added along with 960 mL of tap
water
for the stirring prior to primary froth collection. Following collection of
the primary froth, air
and stirring were restarted for 5 min. Then the secondary froth was allowed to
float up and
was collected.
[0039] A preferred solvent mixture for this use is 15%-25% D-limonene, 25-35%
surfactant, 5%-15% acetone and 35%-45% isopropyl alcohol. A more preferred
solvent
mixture for this use is 18%-22% D-limonene, 28-32% surfactant, 8%-12% acetone
and
38%-42% isopropyl alcohol. The remarkable thing is that only 1 mL of the
solvent mixture
was used to treat 500 g of oil sand ore in just over 1 L of water. The most
useful range of
the solvent mixture appears to be about 0.1 mL to about 5 mL per 100 g of ore.
Larger
amounts of the mixture can be used, of course. Because the minimum amount of
surfactant is 35%, the formula cannot contain more than 65% mixed organic
solvents.
This comes out to 1.3 mL solvent per kilogram of ore or 1.3 L of solvent per
metric ton of
ore. This means that the actual concentration of solvents or surfactants
released into the
environment is extremely low. This also makes the cost of the solvent
composition
essentially insignificant. Even more important is that the small amounts of
biodegradable
solvents (and surfactants) that are added to the environment are essentially
nontoxic. In
terms of added pH builder about 16 g of sodium carbonate are used per kilogram
of ore
which equals about 1.6 kg of sodium carbonate per metric ton of ore¨again a
negligible
quantity.
[0040] Fig. 1 shows the results of the inventive composition versus the
control.
Interestingly, the primary froth recovery was essentially identical for the
control and the
treatment, but the secondary froth recovery was dramatically higher for the
treatment.
Therefore, the total bitumen recovered for the control was 60% while that for
the
treatment was 79% which is essentially the recovery level produced by the
traditional hot
water system. Thus, the inventive process recovers the same amount of bitumen
with a
much lower energy burden to heat the water and without using sodium hydroxide
and
extremely high pH values. In fact, the middlings after the removal of froth
and sand had a
pH of only 8.6 whereas the control pH was 7.8. Quality measurements of the
froths
according to the methods developed by Sanford and Seyer showed that the
qualities
were comparable except that the treatment method produced froths having a
lower level
of solids (e.g., sand and clay particles). This is good because it reduces the
amount of
purification that the recovered bitumen must undergo. However, the primary
froth from the
treatment contained somewhat more water than the control. This appears to be
related to
the chain length of the surfactant (i.e., the hydrophilic-lipophilic (HLB)
characteristic).
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Certain sand particle whose advancing water contact angles (Ga) are in the
range of 15-
.
600 demonstrate a repulsive hydration force at relatively short separation
distances.
Appearance of the strong hydrophobic force is due to the likelihood that the
double-chain
cationic surface can create a higher hydrocarbon chain packing density than
the single-
chain cationic surfaces, thereby resulting in a significantly lower water
inclusion in the
froth while still rejecting solids. The ideal surfactant blend would create an
HLB value
between 12 and 16.
[0041] To demonstrate the innocuous characteristics of these ingredients a
toxicology
test was performed on the minnow Pimephales promelas. The test material was a
2%
aqueous solution of the solvent composition. At the preferred use amounts (1
mL per liter)
the effluent concentration would be 0.1% rather than 2%. It is assumed that
the effluent
would be further diluted before reaching the environment. The effluent was
tested by
treating the minnows with 750 mg/L of the effluent (a further dilution of over
1,000 fold).
The diluted effluent showed no effect on the fish indicating that even without
natural
degradation of the active ingredients, simple dilution is sufficient to render
the solvent
composition innocuous. In actual practice, all of the solvent ingredients are
biodegradable
so that even less of the active ingredients will ever reach the environment.
In addition, a
certified microtox analysis was carried out using Vibrio fischeri as a test
organism. Again,
a 2% dilution of the material was tested at a dilution of 10g/L of test
solution using 2%
NaCI to achieve osmotic balance. A 50% dilution series (50g/L down to 0.39g/L)
was
carried out with a Model 50 benchtop unit following the procedures given in
"Microtox
Acute Toxicity Basic Test Procedures (1995) Microbics Corporation, Carlsbad,
CA" and
"Biological Test Method: Toxicity Test Using Luminescent Bacteria."
(November1992).
Report EPS 1/RM/24. Environment Canada. This produced an 15-min EC50 (mg/L) of
4.30 with a 95% confidence limit of 3.76 - 4.91 with a zinc sulfate reference
toxicant. This
translates to a Cumulative mean EC50 ( SD) for 20 tests of 4.02 0.91. This
indicates
extremely low toxicity.
[0042] The following claims are thus to be understood to include what is
specifically
illustrated and described above, what is conceptually equivalent, what can be
obviously
substituted and also what essentially incorporates the essential idea of the
invention.
Those skilled in the art will appreciate that various adaptations and
modifications of the
just-described preferred embodiment can be configured without departing from
the scope
of the invention. The illustrated embodiment has been set forth only for the
purposes of
example and that should not be taken as limiting the invention. Therefore, it
is to be
understood that, within the scope of the appended claims, the invention may be
practiced
other than as specifically described herein.
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