Note: Descriptions are shown in the official language in which they were submitted.
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SEPARATION AND RECOVERY OF BITUMEN OIL FROM TAR SANDS
BACKGROUND OF THE INVENTION
01 This invention relates to a method for separating bitumen oil from tar
sands and the like.
02 The current industry practice for extracting bitumen from tar sands and the
like is the hot
water process, utilizing aggressive thermal and mechanical action to liberate
and separate the
bitumen. The hot water process is typically a three-step process. Step one
involves conditioning
the oil sands by vigorously mixing it with hot water to completely
disintegrate the oil sands. Step
two is the gravity separation of the sand and rock from the slurry, allowing
the bitumen to float
to the top where it is concentrated and removed as a bitumen froth. Step three
is treatment of the
remainder slurry, referred to as the middlings, using froth floatation
techniques to recover
bitumen that did not float during step two. To assist in the recovery of
bitumen during step one,
sodium hydroxide, referred to as caustic, is added to the slurry in order to
increase the pH of the
slurry. This has the effect of promoting the separation of the bitumen from
the clay and slica
minerals.
03 A problem related to the industry practice is that the addition of caustic,
coupled with the
vigorous and complete physical dispersal of the fmes, produces a middlings
stream that may
contain large amounts of well dispersed fines held in suspension. The recovery
of bitumen from
these middlings stream increases with the increase in the fines concentration
over time. In
addition, the middling stream that remains following step three, referred to
as the scavenging
step, poses a huge disposal problem. Current practice for the disposal of the
resultant sludge
involves the pumping of the sludge into large tailings ponds. This practice
poses serious
environmental risks.
04 The industry practice for the extraction of bitumen from oil sands has been
to maximize
the recovery of bitumen while minimizing the production of sludge, which
require treatment and
disposal. The industry practice typically provides for a bitumen recovery of
between about 80 %
and 95 % of the total amount of bitumen contained in the oil sands. Lower
bitumen recoveries
are experienced with oil sands of high fme material and low bitumen contents.
To increase
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bitumen recovery, methods have arisen to reheat and recycle water recovered
during the solids
de-watering phase to rewash the sand settled in the primary separation vessel,
whereby the
dispersed fine material may undergo further froth floatation treatment for
bitumen recovery.
SUMMARY OF INVENTION
05 A process for the separation of bitumen oil from tar sands and the like is
disclosed.
Slurry is supplied to a mixing chamber, for example the mixing chamber of a
jet pump, at an
input point of the separation process. Non-ionic surfactant is added to the
slurry. The slurry is
agitated within the jet pump and passes into a pipeline to effect a partial to
full phase separation
of the oil and water fraction from the solids fraction of the slurry. The non-
ionic surfactant helps
prevent re-agglomeration of the solids and oil fraction. The partially to
fully separated fractions
of the slurry are discharged into a hydrocyclone to effect a second phase
separation of the slurry.
One or more hydrocyclone separators may be used to separate and concentrate
any remaining
residual bitumen oil and liquid from the solids fraction. Diluent may be added
to the slurry prior
to the mixing chamber to soften the tar sands prior to phase separation.
06 The process distinguishes itself from others in that it does not
contemplate the use of
elutriation vessels, clarifiers, separators, baths or similar devices to
condition and/or to separate
the oil and liquids from the solids fraction. An aspect of the invention is
that bitumen separation
is achieved during mixing in the presence of a non-ionic surfactant, for
example within the jet
pump and within the pipeline. The extraction of bitumen oil from the tar sands
and the release of
the solid particles from the oil sand matrix continues in the slurry exiting
the jet pump as the jet
pump transports the slurry to the material separation and classification
process.
07 Pre-conditioning of the raw material is not a requirement of this process,
greatly reducing
the infrastructure of the plant, although diluent may be added to soften the
bitumen. Rather the
solids fraction of the slurry is physically and/or chemically conditioned by
the wash fluid and
non-ionic surfactant. The use of elutriation vessels, clarifiers, separators,
baths or the like are
replaced with hydrocyclone separators. The hydrocyclone separators are
designed to separate
and classify the slurry stream using centrifugal forces into two stream
fractions consisting of
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water and oil and solids. The process can be applied to separate bitumen
attached to any type of
solid. Further, multiple wash step loops are possible to maximise bitumen
separation and
recover, or to achieve any level of treatment recovery desired.
08 An apparatus according to an aspect of the invention comprises hopper,
motive pump,
mixer such as a jet pump, pipeline, source of non-ionic surfactant, and
hydrocyclone separator.
The hopper is designed to receive the raw material and can be shaped as a cone
bottom vessel or
alternatively equipped with a mechanical auger designed to convey material to
the inlet of the jet
pump. The motive pump is designed to supply the high pressure fluid necessary
to operate the jet
pump which by use of a nozzle within the jet pump the fluid is converted into
a high velocity jet
to produce a vacuum within the mixing chamber of the jet pump to suction the
tar sands into the
inlet of the jet pump. Further aspects of the invention are described in the
detailed description
that follows.
BRIEF DESCRIPTION OF THE DRAWINGS
09 An exemplary embodiment is now described in detail with reference to the
drawings, in
which:
FIGS. IA-1F are flow charts of a process of separation and recovery of bitumen
from tar
sands in which the proposed invention may be used, in which Fig. 1A shows a
first wash
treatement process of the input slurry with water, Fig. 1B shows wash steps
with solvent on the
heavier output from the steps of Fig. lA, Fig. 1C shows wash steps with water
on the heavier
output from Fig. 1 B, Fig. 1 D shows a first oil\water separation treatment
process on the lighter
output from the process of Fig. IA, Fig. IE shows process steps for the
treatment of de-watered
solids using a thermal screw, Fig. 1 F shows treatment of recovered wash water
and Fig. 1 G
shows the interrelationship of Figs. lA-1F;
FIG. 2 is a schematic of the feed hopper, jet pump, pipeline and hydrocyclone
according
to the invention; and.
FIG. 3 is a detailed schematic of a jet pump for use in a method according to
the
invention.
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DETAILED DESCRIPTION OF THE DRAWINGS
With reference to Figs. lA-1F, an overview of a process for the separation and
recovery
of bitumen oil from tar sands and the like is described. Tar sands, also
referred to as oil sands,
are a matrix of bitumen, water, and mineral material. The bitumen consists of
viscous
hydrocarbons, which acts as a binder for the other components of the oil sand
matrix. A typical
deposit of oil sand will contain about 10 % to 12 % bitumen and about 3 % to 6
% water. The
mineral material consists of rock, sand, silt and clay. Clay and silt are
considered to be fmes.
Mineral material can contain about 14 % to 30 % fines. Although it is
understood that the
described process and apparatus may be applied to removing oil from any type
of particulate
material, in accordance with a preferred embodiment of the invention, the
process and apparatus
are applied to separating and recovering bitumen oil from tar sands, such as
that derived from
mining or drilling operations.
11 As shown in Fig. lA, unprocessed tar sands or tailings 1 from a mining or
drilling
operation may be fed into a receiving hopper 2 via a preferably a belt
conveyor 3 or alterna.tively
via a front end loader 4 at an input end of the tar sands separation process.
At the input end, the
unprocessed tar sands have undergone little or no processing, and no phase
separation but are
preferably treated with a hydrocarbon diluent before or upon being fed into
the hopper 2. The
diulent may be supplied from a supply D of diluent injected through line D 1
into the hopper 2.
The diluent is a hydrocarbon fluid that has lighter components than the
bitumen in the
unprocessed tar sands. Preferred diluents are predominantly composed of C6 to
C 12
hydrocarbons, and may be for example a readily available hydrocarbon such as
naphtha or diesel.
The diluent is added in an amount sufficient to reduce the density of the
bitumen, and may be
added for example in an amount by weight equal to the amount by weight of
bitumen in the
unprocessed tar sands.
12 The belt conveyor 3 features a troughed belt on 20 degree or greater idlers
and are readily
available in the industry. The receiving hopper 2 may be supplied with a
mechanical grinder 5
and has its discharge coupled to a jet transfer pump 6. The mechanical grinder
5 is also readily
available in the industry. The jet pumps 6 is also readily available in the
industry, such as those
manufactured by Genflo Pumps, but some care must be taken in choosing the jet
pump, and it is
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preferred to use the jet pump shown in Fig. 3. The jet pump 6 should operate
at a high Reynolds
number, above 250,000, and preferably in the order of 650,000 to 750,000. Such
a Reynolds
number may be obtained by a combination of high pressure, for example 80 psi
or more, and a
sufficiently long mixing chamber, as for example shown in Fig. 3. All jet
pumps described in
this patent document preferably have this configuration.
13 As the tar sands enter the receiving hopper 2 they may be mechanically
ground,
preferably using a horizontal shear mixer 5 to produce particles 50mm in size
or smaller. The
jet transfer pump 6 at the respective base of cone 7 of the receiving hopper 2
mixes the ground
tar sands 1 with a water stream from line 8 to produce a slurry mixture in
line 9 which is passed
into a first hydrocyclone separator 10. A non-ionic surfactant from surfactant
source S is added
to the line 8 through line S 1.
14 Centrifugal forces within the first hydrocyclone separator 10 separate a
large portion of
the solids from the bitumen oil and water mixture. The solids are removed from
the bottom of
hydrocyclone separator 10 and gravity discharged into cone bottom hopper 11.
The remaining
slurry mixture, comprising primarily of the bitumen oil and water, in line 12,
is gravity
discharged into a centrate collection tank 13. Any residual solids in this
stream settle to the
bottom of the centrate collection tank 13. The oil and water are removed from
the top at point 14
of the centrate collection tank. A further jet transfer pump 15 located at
base 16 of the centrate
collection tank 13 removes and mixes the solids with the hot water stream in
line 17 and passes it
through line 18 to a second hydrocyclone separator 19. Centrifugal forces
within the second
hydrocyclone separator 19 separate the remaining portion of the solids from
the oil and water
fractions. The solids are removed from the bottom of hydrocyclone separator 19
and gravity
discharged into the cone bottom hopper. A jet transfer pump 20 located at base
21 of the cone
bottom hopper 11 removes and mixes the solids with the water stream in line 22
and passes it
through line 23 to the inlet of centrifuge 24. Optionally, the water wash step
can be repeated
multiple times with each step identical to the preceding step. Non-ionic
surfactant from source S
may be added through line S2 to line 22 at the inlet to pump 20.
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15 The surfactant is added to line 8 and 22 in an amount that avoids
generating an emulsion
in the line 9 and line 23 respectively while helping to prevent re-
agglomeration of bitumen and
solids after de-agglomeration in the jet pump 6 and 20. A flow rate of non-
ionic surfactant less
than 0.025% by weight of the total slurry flow at the exit of the jet pump 6
or jet pump 20 is
believed to avoid generating an emulsion. To prevent re-agglomeration of
bitumen and solids,
the non-ionic surfactant should have a flow rate of more than 0.005% by weight
of the total
slurry flow rate. Hence, if the slurry flow equals 100 kg per second, then the
amount of non-ionic
surfactant should be in the amount of more than 5 g per second and less than
25 g per second,
preferably around 10 g per second (corresponding to 0.01 % by weight). The
diluent helps to
soften the bitumen, while the non-ionic surfactant acts as a wash aid that
assists in separating the
bitumen from solids in the hydrocyclone separator 10 or centrifuge 24. The
effect of the non-
ionic surfactant allows the water stream in line 8 and 22 to be at a
relatively low temperature,
such as the typical ambient 20C of a tar sands plant, although the process may
be operated at
lower or higher temperatures. Preferred non-ionic surfactants in source S
include
alkylphenolethoxylates such as octylphenylpolyethoxyethanols or
nonylphenylpolyethoxyethanols available from Dow Chemical. It is preferred
that the process be
carried out at or near neutral pH, for example in the range 6-8, to avoid
emulsification of the oil
and water by the action of the surfactant. Too high a pH will tend to promote
emulsification.
16 As shown in Fig. 1B, solids removed from the bottom of the cone bottom
hopper 11 are
de-watered using centrifuge 24, preferably a basket or solid bowl centrifuge.
Alternative
mechanical dewatering technology such as inclined dewatering screws or belt
filter presses can
also be used. De-watered solids 25 are discharged into a cone bottom receiving
hopper 26. A jet
transfer pump 27 at the base of the cone 28 of the receiving hopper 26 mixes
the solids with a
solvent stream from line 29 to produce a slurry mixture in line 30 which is
passed into a
hydrocyclone separator 31. The solvent stream may be heated. Centrifugal
forces within the
hydrocyclone separator 31 separate a large portion of the solids from the oil
and solvent mixture.
The solids are removed from the bottom of hydrocyclone separator 31 and
gravity discharged
into the cone bottom hopper 32. The remaining slurry mixture, comprised
primarily of the oil
and solvent, in line 33, is gravity discharged into the centrate collection
tank 34. Any residual
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solids in this stream settle to the bottom of the centrate collection tank 34.
The oil and solvent are
separated from the top of centrate collection tank at point 35. The jet
transfer pump 36 located at
the respective base 37 of the centrate collection tank 35 mixes the solids
with a solvent stream in
line 38 and passes it through line 39 to the second hydrocyclone separator 40.
Centrifugal forces
within a second hydrocyclone separator 40 separates the remaining portion of
the solids from the
oil and solvent mixture. The solids are removed from the bottom of
hydrocyclone separator 40
and gravity discharged into the cone bottom hopper 32. Optionally, the solvent
wash step can be
repeated multiple times with each step identical to the preceding step. The
solvent stream in line
38 may be heated.
17 Referring to Fig. 1C, solids that are deposited in cone bottom hopper 32
are removed via
jet pump 41 at base 42 and de-watered by centrifuge 43, preferably using a
basket or solid bowl
centrifuge. Other alternative mechanical dewatering technology can be used
such as inclined
dewatering screws and or belt filter presses. De-watered solids 44 are gravity
discharged into a
cone bottom receiving hopper 45. Jet transfer pump 46 at the base of the cone
47 of the receiving
hopper 45 mixes the de-watered solids with a water stream from line 48 to
produce a slurry
mixture in line 49 which is passed into a hydrocyclone separator 50.
Centrifugal forces within
the first hydrocyclone separator 50 separate a large portion of the solids
from the oil and water
mixture. The solids are removed from the bottom of hydrocyclone separator 50
and gravity
discharged into cone bottom hopper 51. The remaining slurry mixture, comprised
of the oil and
water, in line 52, is gravity discharged into centrate collection tank 53. The
solids settle to the
bottom of the centrate collection tank 53. The oil and water are removed from
the top at point 54
of the centrate collection tank. Jet transfer pump 551ocated at base 32 of
centrate collection tank
56 removes and mixes the solids with a water stream in line 57 and passes it
through line 58 to a
second hydrocyclone separator 59. Centrifugal forces within the second
hydrocyclone separator
59 separate the remaining portion of the solids from the oil and water
mixture. The solids are
removed from the bottom of hydrocyclone separator 59 and gravity discharged
into the cone
bottom hopper 51. Optionally, the hot water wash step can be repeated multiple
times with each
step identical to the preceding step. If necessary, further non-ionic
surfactant may be added to the
lines 48 and 57 in the same manner as in lines 8 and 22. As a further option,
the solids collected
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from cone bottom hopper 51, mostly clays and silts, can be further treated by
further thickening
then fed into a thermal screw. There, the solids may be mixed with calcium
oxide. The use of
calcium oxide is contemplated in an embodiment of the invention to chemically
condition the
solids. Calcium oxide addition is to coagulate the solids to release sorbed
water, which if added
in sufficient concentration will locally increase the temperature of the
solids, coupled with the
heat input form the other direct and indirect heating systems can cause the
water and any residual
hydrocarbons to vaporize. The thermal screw may be equipped with a vapour
recovery system
since the reaction would be exothermic. A dry solids stream is produced after
the oxidation of
any remaining hydrocarbons in the clay and silt slurry.
18 Solids that are deposited in the cone bottom hopper 51 are removed via jet
pump 60 at the
base 61 and mixed with a water stream in line 62 and passes it through line 63
to the inlet of
centrifuge 64, which is for example a basket or solid bowel centrifuge. Other
alternative
mechanical dewatering technology can be used such as inclined dewatering
screws and/or belt
filter presses. De-watered solids 65 can be optionally discharged into
receiving pile 66 or
alternatively discharged into cone bottom receiving hopper 67 for thermal
treatment. Solids
requiring additional thermal treatment for treatment and recovery of any
residual hydrocarbons
or alternatively for further drying are to be blended and mixed with calcium
oxide in a controlled
manner directly within the thermal screw at the inlet point of the thermal
screw. Mixing
calcium oxide with moist solids chemically reacts with the moisture associated
with the solids to
locally increase the temperature of solids through direct heating caused by
the exothermic
reactions, causing both moisture and residual hydrocarbons to vaporize. The
mix ratio of
calcium oxide is a function of the desired temperature increase, which to
achieve can require the
addition of water to the solids in hopper 67. Residual de-watered solids,
consisting of the clays
and silts recovered from the wastewater treatment process can be discharged
via line 68 into the
cone bottom receiving hopper 67 for thermal treatment.
19 Referring in particular to Fig. 1E, subsequently, and optionally, a thermal
screw 69 may
be used to treat a portion of the entire solids fraction for removal of any
residual hydrocarbons or
alternatively for further drying. The thermal screw 69 is configured to
contemplate the direct and
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indirect heating of the solids for treatment by exposing the solids directly
to direct heat produced
through the addition of calcium oxide and through the addition of either hot
exhaust gases from a
combustion engine or alterna.tively a hot inert gas. Calcium oxide is to be
metered directly into
the thermal screw at the inlet point for blending and mixing with the solids.
Indirect heating is
provided by the heater system 73 which can consist of the heating of the
outside trough surface
of the thermal screw using electric heaters, or an outside jacket designed to
receive and circulate
hot oil or alternatively steam for contact with the surface. A rotary valve 70
at the base of cone
71 of the receiving hopper 67 meters the de-watered solids into the thermal
screw 69. A rotary
valve (not shown) at the base of cone 174 meters calcium oxide into the solids
fraction as it
enters the thermal screw 67. Both rotary valves are equipped with a variable
frequency drive to
provide operational control of the feed input. The thermal screw 69 preferably
consists of a
screw conveyor complete with a gas manifold collection system 72, heating
system 73, cooler
74, gas-liquid separator 75, blower 76, inert gas storage system 77, and inert
gas recycle system
at point 78. The de-watered solids are introduced into the thermal screw at
point 69. Hot inert
gas from the inert gas recycle system 78 or alternatively the hot exhaust
gases from a combustion
engine (not shown) is introduced into the thermal screw using a rotary swivel
at 79 via line 80.
Prior to introduction into the thermal screw 69 the inert gas is indirectly
heated to the operating
temperature of the thermal screw through the wrapping of the inert gas line 81
between the
heater system 73 and body of the thermal screw 82. In the case where hot
exhaust gases are used,
the gases can be injected directly into the thermal screw without indirect pre-
heating of the gases.
Hot gases 83 from within the thermal screw 69 consisting principally of
vaporized hydrocarbons
and water vapor are removed under a vacuum in the case where an inert gas
storage supply is
used or alternatively under positive pressure in the case where hot exhaust
gases from a
combustion engine are used for direct heating and the maintaining of a non-
oxidizing
environment within the thermal screw from the thermal screw via line 84 at
multiple gas
discharge ports on top of the screw housing shown at the respective locations
85, 86 and 87.
20 The hot gases removed from the thermal screw via line 84 are separated into
two gas
streams at point 88. Hot gases in line 89 are passed into the water knockout
drum 90 for water
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removal after which the gases pass through line 91 to the fuel inlet system of
the gas fired co-
generation unit 92.
21 Hot gases in line 93 are passed into the cooler at point 94, where the hot
gas mixture is
cooled using an air cooler 74. Alternatively, a chiller may be used instead.
Exiting via line 95
from the cooler 74 is a cooled multi-phase mixture consisting of the inert gas
and liquid droplets
of oil and water. The mixture enters the gas-liquid separator 75 at point 96
where the condensate
is separated from the inert gas. The inert gas exits the gas-liquid separator
75 via line 98.
22 Blower 76, preferably a rotary lobe blower, withdraws the hot gases from
the thermal
screw under a vacuum or positive pressure depending on the source and nature
of the hot gases
used for direct heating and maintance of the non-oxidizing environment. The
blower is equipped
with a variable speed drive to control the vacuum pressure under which the
thermal screw 69 is
operated.
23 The inert gas is discharged from the blower 76 via line 99, where at point
101, the line is
split into two gas streams shown via lines 102 and 103. Control valves 104 and
105 and gas flow
meter 106 regulate the inert gas flow that is recycled to the thermal screw
69. Inert gas via line
107 and recycled gas 108 are indirectly heated using the hot outside surface
of the thermal screw
housing before entering the swivel connection at 78 of the holoflyte screw
auger of the thermal
screw. Excess exhaust gas, via line 102, enters a vapor recovery unit 109
where the gas is fiarther
chilled to remove any residual hydrocarbons and vaporized metals. The inert
gas is discharged
from the vapor recovery system via line 110 to the atmosphere at point 111.
Optionally the entire
inert gas stream via line 99 can be recycled via line 103 or alternatively
discharged via line 102
to be processed by the vapor recovery unit 109 as would be the case for hot
exhaust gases
utilized from a combustion engine for direct heating.
24 Referring in particular to Fig. 1D, oily materials separated by
hydrocyclone separators
10, 19, 31, 40, 50 and 59 and discharged into centrate collection tanks 13, 34
and 53 via lines 12,
35, and 52 are treated separately for the recovery of bitumen oil for the
different oil-water
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mixtures via lines 112 and 114 and oil-solvent mixture streams via line 113.
All, or a portion of
all, the solids fraction de-watered using the centrifuges 115 and 116 are
gravity discharged into
the feed hoppers 45 and 67 of the thermal screw 69. The oil-water fraction of
the oily material
deposited in centrate collection tank 13 overflows via line 112 into the
floatation unit 115. Air is
introduced via a line 116 into the floatation unit through fme bubble
diffusers at 117 to produce
fme bubbles to float and concentrate the bitumen oil to produce a froth which
discharges via line
118 into the oil-water separator 119.
25 The concentrated oil-water mixture is removed at point 120 of the
floatation unit 115 and
passed via line 118 to the oil/water separator 119. The oil water separator
119 separates the oil
from the water, with the oil removed via line 121 and passed into the oil
storage tank 122. The
water is removed via line 123 which then interconnects with line 124 to form
line 125 which is
passed into a rapid mix tank 126.
26 The water mixture enters the rapid mix tank 126 where it is treated with
primary
coagulant 127 introduced via a line into the mix tank 128. Synthetic polymers
are the preferred
coagulant, but metal-based coagulants can also be used. The treated water
mixture exits the rapid
mix tank 126 via line 129 and enters into flocculation unit 130. The treated
water mixture flows
through a series of baffled slow mix chambers equipped with slow rotating
mechanical mixers.
Residual particles in the water mixture are coagulated and agglomerated within
the flocculation
unit.
27 The coagulated water exists the flocculation unit 130 via line 131 and
enters into a
sedimentation tank 132. The coagulated solids are gravity settled in the
sedimentation tank 132.
A jet pump 133 at the base 134 of the sedimentation tank 132 removes and
transfers the
coagulated solids via line 135 to the mechanical de-watering unit 116,
preferably a basket or
solid bowel centrifuge. The de-watered solids exits the centrifuge via line
136 and are transferred
to the cone bottom receiving hopper 67 of the thermal screw 69.
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28 Referring in particular to Fig. 1F, the water from the sedimentation tank
132 overflows
via a weir at point 137 and is discharged via line 138 to a surge tank 139.
From surge tank 139
the water is pumped via line 140 into a filtration unit 141 for the removal of
any residual solids
carryover from the sedimentation tank 132. Residual solids are captured within
filtration unit
141. The clarified water exits the filtration unit 141 via line 142 and enters
storage tank 143.
From the storage tank water enters a vacuum filtration unit 144.
29 Optionally, the filter unit 141 and vacuum distillation unit 144 may be by-
passed via line
145 with the clarified water directly recycled via line 146 to the water
storage tank 147.
30 Clarified water via line 148 enters the vacuum filtration unit 144 where it
is heated under
a vacuum to produce distilled water. Distilled water exits via line 149 from
the vacuum filtration
unit 144 where it is pumped to the water storage tank 147. The brine
concentrate containing the
impurities is discharged from the vacuum filtration unit 144 via line 150 into
the concentrate
tank 151 for disposal. Optionally, the concentrate can be recycled back to the
vacuum filtration
unit using a control loop that relies on the resultant brine concentration for
additional distillation
to recover as much as distilled water as possible.
31 With reference to Figure 2, the operation of a preferred feed hopper, jet
pump and
hydrocyclone is described in further detail. The tar sands material is first
deposited into feed
hopper 152 that has an elongated trough at its base within which lies an auger
153. Diluent is
added through line D1 from source D. The tar sands material is then augured
with auger 153 to
the inlet of the jet pump 154. A pressurized wash fluid 155 is fed to the
inlet nozzle 156 of the
jet pump 154 using a conventional centrifugal pump (not shown). Non-ionic
surfactant from
source S is added to the wash fluid 155 through line S 1. The jet pump inlet
nozzle 156 directs a
flow into the mixer 157 educting the tar sands into the jet pump 154 where
extreme turbulence
and mixing occurs at point 158. The slurry flow slows in velocity in the
diffuser 159. The slurry
then flows into an engineered pipeline 160 of a sufficient length required to
optimize separation
for the wash fluid used from where it enters the entrance of the hydrocyclone
161. A centrifugal
force is created in the upper chamber 162 of the hydrocyclone. The solids are
forced to the
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outside of the hydrocyclone at point 163 and the wash fluid and bitumen are
forced to the center
of the hydrocyclone at point 164. The solids exit the hydrocyclone at the
vortex 165 as an
underflow. The wash fluid and bitumen exit the hydrocyclone as an overflow at
point 166 at the
top of the hydrocyclone. The wash fluid and bitumen are transported in a
flexible pipeline 167 to
the next phase which can be a repeat of the first step.
32 With reference to Figure 3, the operation of the jet pump 154 is described
in further
detail. Unlike other pumps, a jet pump has no moving parts. A typical jet pump
consists of the
following: a jet supply line 168, a nozzle 169, a suction chamber 171, a
mixing chamber 172 and
a diffusor 173 leading to a discharge line. In a jet pump, pumping action is
created as a fluid
(liquid, steam or gas) passes at a high pressure and velocity through the
nozzle 169 and into a
chamber 171 that has both an inlet and outlet opening. Pressurised wash fluid
is fed into the jet
pump 154 at jet supply line 168. The wash fluid passes through inlet nozzle
169, where it meets
tar sand material gravity fed from hopper inlet 170 at the suction chamber
171. The resulting
slurry is mixed and agitated within the mixing chamber 172 where it undergoes
an initial phase
separation of oil fraction from solid fraction. The agitated slurry slows in
velocity in the diffuser
173. Upon entry into the jet pump 154, the tar sands material from hopper 152
is entrained and
mixed with the wash fluid from the nozzle 169, which undergoes a substantial
pressure drop
across the jet pump 154 and causes extreme mixing of the slurry. The extreme
mixing and
pressure drop causes cavitation bubbles to develop on the inside of chamber
171, which implode
on solid particles to enhance the separation of the bitumen oil from the solid
particles.
33 The jet pump used with the present invention functions as an ejector or an
injector or an
eductor, distinct from a venturi pump and an airmover. A venturi has little in
common
conceptually with a jet pump. A venturi is a pipe that starts wide and
smoothly contracts in a
short distance to a throat and then gradually expands again. It is used to
provide a low pressure.
If the low pressure is used to induce a secondary flow it becomes a pump,
resulting in a loss of
pressure in the throat. If the secondary flow is substantial the loss will be
too great to have a
venturi operate like a pump. To operate like a pump it would have to be
redesigned as a jet
pump. Venturi pumps have limited capacity in applications like chemical dosing
where a small
CA 02531007 2005-12-12
14
amount of chemical is added to a large volume of fluid. A jet pump is a pump
that is used to
increase the pressure or the speed of a fluid. Energy is put into the fluid
and then taken out by a
different form. In a jet pump energy is added by way of a high speed jet fluid
called the primary
flow. In the design shown in Fig. 3, the primary flow is produced by jet
nozzle 169. Energy is
taken out mostly as increased pressure of a stream of fluid passing through.
In a jet pump this
stream is called the secondary flow and it is said to be entrained by the
primary flow. A jet pump
is designed to be energy efficient. A venturi pump does not have the capacity
to induce large
volumes of flow, where as a jet pump can and operate energy efficient. Unlike
a venturi pump, a
jet pump consists of a nozzle, mixing chamber and diffuser. In a jet pump
these components are
specifically engineered to have the pump operate energy efficient. A venturi
pump does not have
a defmed nozzle, but instead a constriction in the pipe. It also does not have
a defmed mixing
chamber.
34 The wash fluid can be combination of fluids used singularly or in
combination in multiple
loops consisting of a chemically treated or chemical free hot or cold water or
alternatively a hot
or cold solvent. As disclosed above, in the case of water used as a wash
fluid, non-ionic
surfactant is added to the wash fluid to prevent re-agglomeration of solids
and bitumen, and to
enhance solid-bitumen separation. The wash fluid can chemically and/or
physically react with
the bitumen oil to partition the oil to the liquid phase to permit separation
and recovery by
hydrocyclone separation. The continuous supply of wash fluid by the motive
pump provides for
the transport of the tar sands carried in a wash fluid stream to continue the
extraction of bitumen
from the oil sands in the pipeline. Hydrocyclone separator 161 is used to
classify and remove the
bitumen oil and water fraction from the solids fraction, with the solid
fraction deposited into a
second hopper. If necessary, the solids fraction can be repeatedly treated for
additional bitumen
recovery by repeating the process.
PROCESS CONDITIONS
35 As the tar sands enter the receiving feed hopper, they are mechanically
ground,
preferably using a horizontal shear mixer, to reduce the solid particles to 25
mm in size or
smaller and mixed with diluent. The motive pump (not shown), preferably of a
centrifugal
CA 02531007 2005-12-12
pump, is configured to draw a cold wash water with non-ionic surfactant from a
water tank to
produce a high pressure water stream at the inlet of the jet pump. By cold in
this context means
between about 1C and 27C, and may be between lOC and 20C. At the jet pump
inlet the high
pressure water stream, at approximately 120 psi, is converted within the jet
pump nozzle into a
high velocity water jet, referred to as the primary flow. The substantial
pressure drop within the
jet pump draws the slurry mixture from the hopper, referred to as the
secondary flow, into the jet
pump where it is mixed with the primary flow to achieve a resultant percent
solids concentration
of 25 % or less by volume.
36 The optional treatment of the clays and fines, collected after the solids
are collected from
the first wash process, would be thickened to approximately 60% solids before
being fed into the
thermal screw.
37 This invention therefore contemplates the use of non-ionic surfactants
added to the wash
stream of jet pumps to effect separation of oil from solid particles. This
method distinguishes
itself from other processes in that it does not contemplate the use of
elutriation vessels, clarifiers,
separators, baths or the like to condition and or separate the oil and liquids
from the solids
fraction. Bitumen separation is achieved during mixing within the jet pump and
pipeline during
transport. No other vessels or technologies are required to effect separation
of bitumen oil from
solids. Therefore the process is substantially simplified in comparison to
existing hot water or
solvent bitumen extraction processes. The use of centrifugal forces by way of
hydrocyclones and
centrifuges are employed throughout the process for separation and
classification of the different
stream fractions consisting of water, oil, and solids. In accordance with
aspects of this invention,
physical, chemical and thermal processes are employed to separate, treat and
recover bitumen oil
from solid particles, irrespective of the oil and solid type and
concentration. Direct and indirect
heating of the different medias are provided using a variety of chemical and
chemical free
treatment liquid wash and thermal processes to effect separation of bitumen
oil from the solids.
Such process strategy provides for the treatment of all solid particle types,
including those
particles of high surface activity consisting of silts and clays, prone to
adsorb and retain oil
CA 02531007 2005-12-12
16
contamination. Treatment and disposal of the fmes are provided in the process
contemplated,
maximizing the recovery of bitumen.
38 There are no moving parts contacting the slurry, making this process less
mechanically
intensive and subsequently more economical to operate from a O&M standpoint,
compared to
other bitumen recovery processes. Each step of the method is configured and
optimized to
separate bitumen with the end process being bitumen recovery.
39 The method has application in the processing of tar sands, production sand,
drill cuttings
derived from bitumen laden geological formations using water based drill
fluids, contaminated
oily sand or gravel, and contaminated soil.
40 In a further embodiment, non-ionic surfactant can be mixed with a water
wash fluid and
added to a tar sands slurry with or without added diluent. The non-ionic
surfactant is added in
the same proportions as used with the jet pumps. However, in this embodiment,
jet pumps need
not be used, or jet pumps in a pipeline need not be used. Other agitation
methods in a mixing
chamber may be used to separate bitumen from the solids fraction of a tar
sand, such as by use of
rotating paddles, rotating screws, mechanical shaker, high-shear impeller or
jet pumps used
within a bowl acting as a mixing chamber. The duration of agitation may vary
from 2 minutes to
several hours. Once the bitumen and solids are agitated together with the non-
ionic surfactant to
achieve a desired degree of separation, they may be removed separately as a
substantially solid
phase and a substantially liquid phase from the fluid stream by using
hydrocyclones and
centrifuges as described in relation to Figs. lA-1F. The solid phase may then
be subject to
further washing, with for example water, and further agitation, with or
without use of non-ionic
surfactant, to further remove bitumen from the solid phase. The liquid phase
may be separated
into oil and water streams by use of techniques as described in relation to
Fig. 1D and lE, or
other techniques such as air flotation and skimming.
41 Immaterial modifications may be made to the embodiments disclosed here
without
departing from the invention.
