Note: Descriptions are shown in the official language in which they were submitted.
CA 02707577 2010-06-28
Mr. Jan Kruyer, P.Eng. Box 138 Thorsby, Canada TOC 2P0
SCALING UP THE OLEOPHILIC SIEVE PROCESS
RELATED APPLICATIONS
This application is related to Canadian Patent applications number 2,704,175
filed approximately May 20th , 2010 entitled "Removing Hydrophilic Minerals
from Bitumen Products", number 2,700,446 filed April 22nd, 2010 entitled
"Speed
of Separation ¨ Mine Face Oil Sand extraction", number 2,690,951 filed January
27th, 2010 entitled "Endless Cable Belt Alignment Apparatus and Methods for
Separation", number 2,661,579 filed April 9th, 2009 entitled "Helical Conduit
Hydrocyclone Methods", number 2,647,855 filed January 15th, 2009 entitled
"Design of Endless Cable Multiple Wrap Bitumen Extractors" and number
2,638,596 filed August 6th , 2008 entitled "Endless Cable System and
Associated
Methods", which are referenced in these specifications by number.
FIELD OF THE INVENTION
The present invention relates to scaling up the oleophilic sieve process for
the
recovery of bitumen from aqueous suspensions of oil sand bitumen and
particulate
solids. The scale up factors described include:
1. RPM of bitumen aglomerators, which impact on the surface speed of
revolving apertured oleophilic screens,
2. Internal diameter of aglomerator drums, and
3. Length of aglomerator drums or width of sieve.
Operation and design information is introduced that will provide adequate
strength of
construction for large size bitumen aglomerators while achieving effective
aglomeration at high rates of rotation, high feedstock throughputs and
efficient
screening to separate bitumen phase from aqueous phase. Accordingly, the
present
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Mr. Jan Kruyer, P.Eng. Box 138 Thorsby, Canada TOO 2P0
invention involves the fields of process engineering, chemistry and chemical
engineering.
=
BACKGROUND OF THE INVENTION
A detailed description of oil sand, tar sand or bituminous sand deposits, and
of
the processing of these ore deposits to produce bitumen product is provided in
the
above referenced patent applications. The Northern Alberta oil sands resource
may in
time be found to contain almost half of the remaining economically recoverable
world
oil reserves.
Alberta oil sand ore consist of sand grains covered with a thin envelope of
water, with the voids between the grains filled with mineral fines, water and
bitumen.
Between 10 and 20 percent of the oil sand ore is less than 100 meters below
the
surface and in time all this ore may be strip-mined after overburden removal.
With
current technology some of the remainder may be recovered by in situ methods
that
use steam or combustion to bring bitumen products to the surface. The current
commercial method for processing mined oil sand, invented by Karl Clark about
80
years ago, mines the oil sand and mixes it with water, process aid and air to
form a
thick aerated slurry that is subsequently flooded with water and then is
separated in
large flotation vessels where aerated bitumen particles rise to the top and
are
skimmed off to become the bitumen products of separation. Steam is used to
remove
air from the bitumen froth product before it is cleaned. The de-aerated
bitumen
product, containing water and mineral particulates, is processed further to
eventually
yield refinery oil products.
An alternate process developed by the present inventor does not use bitumen
froth flotation or flotation vessels but screens bitumen product out of
aqueous oil sand
mixtures. This process was introduced in patents granted to the present
inventor
many years ago, and is disclosed and claimed in more practical detail in his
pending
patents referred to above.
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Mr. Jan Kruyer, P.Eng. Box 138 Thorsby, Canada TOC 2P0
There are several configurations of froth flotation used by the various
commercial plants, and one such configuration may be described with the use of
Figure 1. After the removal and stockpiling of overburden, the oil sand ore is
surface
mined by means of very large mechnical power shovels and is moved by dump
trucks, that can handle 400 tons of oil sand per load, to roll crushers that
break the oil
sand, clay lenses and rocks to a manageable size. In one commercial plant the
crushed oil sand is further broken into smaller sizes using ore breakers
similar in
concept to those disclosed in expired Canadian patent 1,162,899 entitled
"Rotative
Grizzly for Oil Sand Separation" granted to the present inventor on February
28th,
1984.
Commercially the crushed ore is mixed with water and air in a cyclo feeder
and introduced into a slurry pipeline where it flows in turbulent flow for 2
to 10
kilometers to condition the oil sand ore to a digested and aerated slurry
suitable for
separation in a primary separation vessel (PSV) or primary separation cell
(PSC).
Caustic process aid normally is added to properly condition the ore with water
and
form an aerated thick pipeline slurry, that is then flooded with flood water
before it
enters the PSV. Aerated bitumen rises to the top of the PSV or PSC and is
skimmed
off as the froth product, which is cleaned up thereafter to remove air, water
and solids
to produce a product that can be upgraded to synthetic crude oil or that can
be diluted
and shipped by pipeline to a refinery. In the commercial plants the middlings
and
bottoms of the PSV are pumped to a tailings oil recovery vessel (TORY) or to
subaeration flotation cells to float off additional bitumen froth which in
some cases is
returned to the PSV or PSC for recovery. From there the tailings flow to a
tailings
pond. Commercial plants have many flow loops and careful control is required
to
optimize bitumen recovery which averages between 80 and 95 percent depending
on
plant configuration and on the grade and type of oil sand ore processed. The
many
suspension flow loops, shown for example in Figure 1, are labour intensive and
require careful chemistry and flow control for plant optimization. The bitumen
product of a commercial oil sand froth flotation plant averages about 60 wt%
bitumen, 10 wt% mineral solids and 30 wt% water.
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Mr. Jan Kruyer, P.Eng. Box 138 Thorsby, Canada TOC 2P0
Flooded pipeline slurry takes about 70 minutes or more of residence time in a
typical commercial oil sands plant to achieve acceptable bitumen recovery. Any
residual unrecovered bitumen ends up in the tailings ponds and represents a
loss of
revenue. The reason for the required long bitumen froth flotation residence
time may
be found in the fact that it takes time for bitumen particles, attached to air
bubbles, to
rise upwards through an aqueous suspension of downward settling sand, silt and
clay.
The caustic process aid used disperses this aqueous suspension, and make it
less
viscous, so that aerated bitumen can rise ufiward at an acceptable rate, but
it still takes
a long time for bitumen attached to air bubbles to reach the tops of PSV,
TORY. PSC
or subaerqation flotation cells.
The chemistry of mineral particle and bitumen dispersion; the reduction of
slurry viscosity, the effective bitumen attachment to air bubbles in the
presence of
very small clay particles, and the subsequent upward flotation of aerated
bitumen past
downward settling minerals is very complex but is not the topic of the present
invention. The present invention deals with the much simpler process of
screening
bitumen from an aqueous suspension of water and particulate minerals, and
doing so
in an efficient manner, using a residence time that is as short as possible.
Due to the chemical and mechanical procedures used in the current froth
flotation commercial oil sand extraction plants, the commercial tailings
contain altra-
fine mineral particles, small bitumen particles and biwetted solids. These
have a
strong tendency to form colloidal thixotropic gel structures in the fluid
tailings of
tailings ponds after the sand drops out. The gels prevent dewatering of the
fluid
tailings after these have settled to about 30 to 35 percent mineral content.
After that,
the natural compacting of fluid tailings is very slow, and most estimates
suggest that
many hundreds of years will pass before undisturbed mature fluid tailings will
reach
consolidation.
Gel formation in fluid tailings is somewhat analogous to the process that
takes
place when jello powder is dissolved in warm water and is then allowed to cool
and
set to form the familiar jello desert, containing a very high percentage of
bound water.
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Mr. Jan Kruyer, P.Eng. Box 138 Thorsby, Canada TOC 2P0
The concepts described in the present invention and in its companion
copending patents are very different from froth flotation. In the present
invention, oil
sand slurried in water is aglomerated in a revolving aglomerator and the ultra-
fine
minerals and the bi-wetted solids become part of the bitumen product. In this
manner
the gel forming solids are removed, do not report of the tailings, and this
results in
fluid tailings that can be dewatered.
OVERVIEW OF BITUMEN SCREENING
As described in the above referenced patents, bitumen screening does not
make use of bitumen froth flotation in a PSV, PSC, TORV or subearation
flotation
cells, but rather agglomerates the small bitumen particles of a dispersed oil
sand
aqueous slurry and then passes the aglomerated slurry through an endless
revolving
apertured oleophilic screen in the form of multiple adjacent wraps of endless
cable.
Aglomerated bitumen is captured by the cable wrap surfaces and de-bituminized
slurry passes through the slits between cable wraps in a separation zone. The
captured
bitumen is removed from the cable wrap surfaces in a bitumen removal zone, as
described in the above referenced copending Canadian patent application
numbers
2,704,175 , 2,700,446 , 2,690,951 , 2,661,579 , 2,647,855 , and 2,638,596. The
screens do not have cross members, can be made to be very strong and long
lasting
and may be heated before removal, and combed or squeezed by rigid grooved or
by
pliable rubber rollers for easy removal of bitumen from the cable wraps in
bitumen
removal zones. The present invention describes methods and equipment for
optimizing and speeding up the bitumen aglomeration and screening process.
One flow diagram of an oleophilic screen proposed for separating mined oil
sand ore is shown in Figure 2. Oil sand is mined and transported to roller
crushers.
Dump trucks are not shown in this Figure to show one option of locating the
extraction process close to the mine face made potentially possible by the
small size
of separation equipment of the present invention. The crushed ore is conveyed
to a
high speed ablation drum described in application CA 2,700,446 of the present
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Mr. Jan Kruyer, P.Eng. Box 138 Thorsby, Canada TOC 2P0
inventor. As an option, the coarse crushed ore may be broken up by a rotating
grizzly
as desribed in granted patent CA 1,162,899 of the present inventor before
entering the
high speed ablation drum. After removal of rock and gravel oversize by a
vibrating
grizzly, the slurry flows into a confined path hydrocyclone to remove fine
gravel and
coarse sand as described in application CA 2,661,579 of the present inventor
In this
hydrocyclone a small amount of fluid is injected into the slurry along the
confined
path upstream from the hydrocyclone vessel to drive dispersed bitumen from the
outside lane to the inside lane of the confined path and cause more bitumen to
report
to the overflow of the hydrocyclone. This injected fluid may be water, a gas,
or a gas
dissolved at high pressure in water. The fluid essentially washes trapped
bitumen and
ultrafines out of the coarse slurry stream flowing along the outside lane of
the
confined path and moves these to the inside lane.
The confined path hydrocyclone underflow removes fine gravel and coarse
sand from the slurry to prevent blinding of the oleophilic apertured screen by
gravel
and also to reduce the amount of abrasive sand contacting the surfaces of the
screen
cable wraps. The overflow from the hydrocyclone enters the aglomerator. In the
agglomerator drum, bitumen particles adhere to oleophilic surfaces inside the
drum in
increasing thicknesses until shear forces in the drum strip off or slough off
enlarged
bitumen from these surfaces. Thus, dispersed bitumen particles of the shiny
enlarge
in size in the agglomerator before the slurry leaves the agglomerator through
an
apertured cylindrical drum wall. Slurry leaving the drum through the drum
apertures
passes through an oleophilic screen, formed by cable wraps which are in
contact with
the apertured drum wall. Bitumen phase is captured by the screen in a
separation
zone. The screen is in the form of adjacent wraps of endless cable suitable
for
capturing bitumen, and the cable may be plastic rope or metal wire rope or
monofilament.
Bitumen captured by cable wraps in a separation zone is removed from cable
wrap surfaces in a bitumen removal zone to become the bitumen product. The
debituminized slurry, called effluent, representing agglomerated slurry from
which
bitumen has been removed, passes through the apertures of the screen in the
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CA 02707577 2010-06-28
Mr. Jan Kruyer, P.Eng. Box 138 Thorsby, Canada TOC 2P0
separation zone, said apertures comprising the apertures of the agglomerator
drum
partly covered by cable wraps. The effluent of slurry screening joins the
hydrocyclone underflow for dewatering. The mineral particle size of the
effluent is
smaller than the particle size of the hydrocyclone underflow and this allows
the
hydrocyclone underflow to act as a sand filter for removing fines from the
effluent
during dewatering. This water run off may be used as recycle water for
producing
more slurry. Water run off from the solid tailings may additionally be
processed by a
conventional high velocity hydrocyclone shown in Figure 2 to remove part of
its fines
before this water is used to produce more slurry. In that case, the undefflow
of the
conventional hydrocyclone joins the agglomerator and screen effluent for
filtering by
confined path hydrocyclone undefflow.
In the bitumen aglomeration and screening process, most of the ultrafines and
biwetted solids of the oil sand slurry become part of the bitumen phase that
is
recovered from the screen surfaces in a bitumen removal zone, and does not end
up in
the effluent. The water run off from the solid tailings may be returned to the
process
as recycle water since bitumen agglomeration and screening is very tolerant of
fine
mineral content in recycle water. The moist solid tailings of the process may
contain
to 25 percent water, resulting in a need for additional water to prepare more
slurry
in the ablation drum. This additional water may be hot water to achieve a
slurry
20 temperature of about 35 degrees centigrade or lower during winter time
when mined
oil sand ore is frozen. Reagents may be added to this fresh water if needed.
Additional run-of water may be recovered and used for slurry preparation after
the
tailings are returned to the mine site and drained to less than 25 percent
water for site
remediation.
SCALE UP OF AGLOMERATION AND SCREENING
Performance of bitumen aglomerators and apertured oleophilic screens were
studied in the Kruyer Oleophilic Sieve pilot plant. These agglomerators and
screens
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Mr. Jan Kruyer, P.Eng. Box 138 Thorsby, Canada TOC 2P0
were small enough to accommodate the available feedstock and yet were large
enough to give representative data.
One very effective unit was designed for a suspension feed rate of 1.0 metric
ton per hour. However, the test program indicated that the feed rate could be
increased many fold without deteriorating the performance of the separator.
The drum
diameter was 1.108 meters, its length was 0.095 meters and the maximum
designed
rotation rate was 3 RPM. The unit easily handled a feed rate exceeding 2.5
metric
tonnes per hour of suspension, representing approximately 2 cubic meters per
hour, or
two and a half time design capacity at that speed. During the test program it
became
obvious that the separation process could be speeded up significantly by
increasing
RPM of the agglomerator. However, the equipment was not designed for higher
speeds.
Based on these pilot plant tests, a standard aglomerator drum with associated
screen was defined for the purpose of scale up calculations. This standard
drum has a
diameter of 1.0 meter, a sieve width of 1.0 meter and a rotation rate of 1.0
RPM.
For a properly designed separator, sieving is a function of the diameter of
the
apertured cylindrical wall of the aglomerator; but aglomeration is a function
of the
cross sectional area of the aglommerator drum and oleophilic ball loading when
the
drum is partly filled with a bed of balls. Therefore, the overall bitumen
agglomeration and screening scale up factor for this process may be a function
of
agglomerator drum diameter raised to some power between 1 and 2. However for
the
initial calculations it was taken to be a function of drum diameter to the
exponent of
one. Only aditional pilot plant experiments with larger separators can refine
the
actual exponent for separating each suspension feedstock, because each type of
feedstock will require a different amount of aglomeration.
Based on the above discussion, scale up of the equipment will involves three
variables. These are RPM, inside diameter of the apertured cylindrical wall of
the
drum (represented by D) and apertured aglomerator length, which is equal to
the
width of the apertured screen, represented by L. Apertured cylindrical wall is
used
here as a reference since an agglomerator may have a cylindrical wall that is
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Mr. Jan Kruyer, P.Eng. Box 138 Thorsby, Canada TOC 2P0
apertured for only part of its length when extensive aglomeration is required,
or when
the aglomerator drum diameter is small. Generaly, a larger diameter
aglomerator has
a larger ball volume and this results in a higher degree of aglomeration. Thus
the
standard aglomerator drum and associated screen defined for the purpose of
scale up
calculations has a drum diameter of 1.0 meter, a sieve width of 1.0 meter and
a
rotation rate of 1.0 RPM. The following procedure may then be used to
anticipate the
scale up performance of an aglomerator with its associated apertured
oleophilic
endless screen belt.
We first adjust the pilot plant data to 1.0 RPM , which converts the feed rate
into (2)(1)/(3) = 0.67 cubic feed of suspension per hour for a 95 cm long
drum. We
then adjust the pilot plant data to convert it to a standard 1.0 meter drum
diameter.
This results in a feed rate of (0.67)(1)/(1.108) = 0.60 cubic feed of
suspension per
hour. We next adjust the 95 cm long apertured pilot plant drum to 1.0 meter
long to
obtain a standard feed rate of (0.60)(1.0)/(0.095) =6.3 cubic feed of
suspension per
hour with the standard agglomerator and screen.
Thus a standard 1 meter diameter drum, with a 1 meter long apertured
cylindrical wall to serve a 1 meter wide screen and rotating at 1 RPM has a
separating
capacity of 6.3 cubic meters per hour of suspension feedstock. For scale up
calculations, the anticipated feedstock separation capacity of any oleophilic
screen
separator is taken as 6.3 cbic meters per hour multiplied by the agglomerator
diameter
(D) multiplied by the sieve width (L) and multiplied by the drum rotation rate
(RPM).
For effective agglomeration the drum should operate below cateracting bed
speed,
since a cateracting bed may interfere with the agglomerating process for most
oil sand
suspensions. Cateracting of a bed in a revolving drum normally starts around
75% of
the critical drum speed. A more reasonable speed may be less than that, for
example
50% of the critical drum speed. The table below ilustrates the critial speeds
of drums
of various diameters, along with the corresponding cateracting speed based on
75% of
the critical drum speed. These cateracting speeds are for mixtures that do not
contain
viscous bitumen. The presence of viscous bitumen in suspensions tumbling with
balls in an agglomerator will alter to a small degree the cateracting speed.
For that
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Mr. Jan Kruyer, P.Eng. Box 138 Thorsby, Canada TOC 2P0
reason the agglomerators of the present invention should normally be rotated
at a rate
below the cateracting speed.
Diameter. Area. Critical 75% critical Circum. Speed
m. sq. m. RPM RPS m. m./s.
1.108 0.964 40.19 0.502 3.48 1.75
1 0.785 42.31 0.529 3.14 1.66
2 3.142 29.92 0.374 6.28 2.35
3 7.069 24.43 0.305 9.42 2.88
4 12.57 21.15 0.264 12.57 3.32
5 19.64 18.92 0.237 15.71 3.72
6 28.27 17.27 0.216 18.85 4.07
Thus, a 2 meter apertured drum has a cross sectional area of 3.142
square meters, its critical rotation rate is 29.92 RPM and its 75% critical
rotation rate
is 0.374 revolutions per second, its circumference is 6.28 meters, the surface
speed of
the apertured wall is 2.35 meters per second at cateracting speed. The surface
speed
of an apertured oleophilic screen in contact with the apertured drum wall is
the same.
SAMPLE SCALE UP CALCULATION
A typical commercial oil sands extraction plant may have 4 trains, each
processing 7000 metric tons of oil sand ore per hour in a 3 meter diameter
agglomerator to produce 75,000 barrels per day of bitumen suitable for
upgrading.
Determine the anticipated width of the apertured screen.
Assume that 7000 metric tons of water are required to produce the desired
slurry for separation. The total volume of slurry per hour, assuming an oil
sand
density of 2.1 metric tons per cubic meter is (7000)/(2.1)+(7000/(1.0) =
10,333 cubic
meters.
Critical RPM for a 3 meter diameter drum is 24.43 RPM and cateracting
starts at approximately 75%, or 18.3 RPM. Selecting an aglomerator RPM of 15,
CA 02707577 2010-06-28
Mr. Jan Kruyer, P.Eng. Box 138 Thorsby, Canada TOG 2P0
which is below the cateracting speed, and referencing this to the standard
drum
defined above computes into the following result:
The reference drum speed is 1 RPM, diameter is 1 meter, screen width is
1 meter, flow rate is 6.3 cubic meters per hour. The proposed commercial drum
rotates at15 RPM, its diameter is 3 meters, and the flow rate is 10,333 cubic
meters
per hour. The screen width (or agglomerator effective length) is solved for as
follows:
Adjusting for speed: (6.3 m3/hr) (15 RPM/1 RPM) = 95 m3/hr
Adjusting for diameter (95 m3/hr) (3) / (1) = 284 m3/hr
The length is: (10,333 m3/hr) /((284 m3/hr)/ lm)) = 36 meters.
Another approach is (10,333)/((6.3)(15)(3))= 36.4 meters of screen width.
Thus the screen width and the apertured length of the 3 meter diameter
commercial agglomerator is 36 meters to separate a suspension of 7000 metric
tons of
oil sand and 7000 metric tons of water. Alternately two aglomerators may be
used in
parallel that use 18 meter wide sieves, or four agglomerators with 9 meter
wide.screens.. Figure 7 illustrates the relative sizes of a current commercial
primary
separation cell (PSC) and subaeration flotation cells to process 7000 tons of
oil sand
ore per hour are compared with the above two 18 meter long aglomerators that
are
expected to achieve the same suspension throughput and bitumen recovery
efficiency.
AGGLOMERATOR WEIGHT AND PRIOR ART
The weight of a 3 meter diameter, 18 meter long agglomerator partly filled
with tumbling balls and rotating at 15 RPM can be very substantial, requiring
very
rigid drum construction. The pilot plant separator used a perforated steel
sheet for the
agglomerator cylindrical wall and used an endless mesh belt for the apertured
oleophilic screen. Such an apparatus is not strong enough for use in a
commercial
plant using 3 meter or larger diameter drums that need to operate year round
without
major break downs. The present invention describes equipment designs and
operation
that overcome such scale up problems
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Mr. Jan Kruyer, P.Eng. Box 138 Thorsby, Canada TOC 2P0
BRIEF DESCRIPTION OF THE DRAWINGS
Fig. 1. One type of commercial oil sands plant using a PSV and a TORV.
Fig. 2. A general flow diagram for a potential commercial plant processing
mined oil sand by agglomeration and bitumen screening.
Fig. 3A. An internal sectional view along the length of an aglomerator that
uses adjacent steel hoops aligned by steel rods to form the aglomerator
apertured
cylindrical wall. The agglomerator is partly filled with a bed of balls. Fig.
3B
provides construction details of hoops welded to the steel rods and showing
the
location of endless cable wraps between the hoops.
Fig. 4A...A cross sectional view accross the agglomerator of Fig. 3A but also
showing a single cable wrap in contact with the apertured agglomerator wall in
a
separation zone and in contact with rollers in a bitumen removal zone. Fig.
4B. A
multy tine scraper for transfering bitumen from hoops to cable wraps.
Fig. 5A. This drawing is similar to the drawing of Figure 3A but in this case
the agglomerator is separated by an apertured circular disc into two
compartments.
Suspension flows into the first compartment that is filled with tower packings
to
agglomerate the flowing suspension by means of contact with a revolving fixed
bed
of tower packings. After that the partly agglomerated suspension passes
through the
apertured disc into a second compartment that is partly filled with a bed of
tumbling
balls which complete the agglomeration process and kneads the agglomerated
bitumen. Only the second compartment has an apertured cylindrical wall in the
form
of hoops similar to the hoops of the agglomerator of Figure 3A, and provided
with
cable wraps in between the hoops to form a separation zone. Fig. 5B. This
drawing is
similar to Figure 5A except that the first compartment is concentric with the
second
compartment. The first compartment contains a fixed bed of tower packings that
rotate with the agglomerator and the second compartment contains a bed of
tumbling
balls that partly fill this second compartment. The compartments are separated
by a
cylindrial apertured wall in the form of a punched metal sheet rolled into a
cylinder,
mounted inside a set of rigid bars that provide strength and rigidity to the
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Mr. Jan Kruyer, P.Eng. Box 138 Thorsby, Canada TOC 2P0
agglomerator and also prevent major damage by balls to the metal sheet
separating
the two compartments. In this case the cylindical wall of the agglomerator
drum
spans nearly the full length of the drum and is made up of hoops, with cable
wraps in
between, as is the case with Figure 3A. Fig. 5C shows one possible location
for
rollers to support slewing rings of Figure 5A and 5 B. Fig. 5D shows a more
preferred location for rollers to support slewing rings of Figure 5A and 5B.
Fig. 6A shows an internal sectional view of a rotating drum with a cateracting
bed. Fig. 6B is an isometric drawing of the drum of Figure 5A, also showing
the
location of bitumen removal rollers and cable wraps between apertured drum
wall and
rollers, but not showing drum supports or drive. An effluent guide baffle is
shown
under the apertured wall portion of the drum. Fig. 6C. is an isometric drawing
of
multiple wraps of endless cable on two rollers taken from pending patent CA
2,638,596 to show the guide rollers needed to keep multiple wraps of a single
endless
cable on rollers or drums and to prevent the cable from rolling off. Fig. 6D
is a
photograp of a spherical Jaeger Tr-pack
Fig. 7. illustrates the size of the main vessels of a current oil sand
extraction
plant and of an anticipated oleophilic sieve extraction plant with the same
capacity.
As shown, the equipment needed for commercial bitumen screening is expected to
be
at least an order of magnitude smaller than the equipment needed for
commercial
bitumen froth flotation.
DEFINITIONS
Before the present invention is described in greater detail, it is to be
understood that this invention is not limited to the particular structures,
process steps,
or materials disclosed herein, but is extended to equivalents thereof as would
be
recognized by those ordinarily skilled in the relevant arts. It should also be
understood that terminology employed herein is used for the purpose of
describing
particular embodiments only and is not intended to be limiting
It must be noted that, as used in this specification and the appended
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Mr. Jan Kruyer, P.Eng. Box 138 Thorsby, Canada TOC 2P0
claims, the singular forms "a," "an," and "the" include plural referents
unless the
context clearly dictates otherwise. Thus, for example, reference to "a splice"
includes
one or more of such splices, reference to "an endless cable" includes
reference to one
or more of such endless cables, and reference to "the material" includes
reference to
one or more of such materials.
In describing and claiming the present invention, the following terminology
will be used in accordance with the definitions Set forth below. When
reference is
made to a given terminology in several definitions, these references should be
considered to augment or support each other or shed additional light.
"ablation" refers to digesting oil sand ore with water due to turbulence at a
temperature warm enough to cause disengagement of bitumen from water covered
sand grains .
"agglomerating" refers to a process in which an aqueous suspension of
bitumen particles and mineral particulates is contacted by oleophilic
surfaces, such as
from a bed of rotating tower packings with oleophilic surfaces or a bed of
tumbling
oleophilic balls in a drum agglomerator, wherein bitumen coats the surfaces of
the
tower packings or of the ball surfaces in increasing thickness until shear
forces, due to
suspension flow and rotation of the agglomerator, strip enlarged bitumen
particles
from these oleophilic surfaces. In many cases bitumen that coats oleophilic
balls
tumbling in a drum aglomerator will fill the voids between the balls and this
bitumen
will be moved and extruded out of these voids by the kneading action of the
moving
bed of balls surrounded by a revolving cylindrical drum wall. The agglomerated
bitumen normally is extruded to an apertured oleophilic screen in contact with
a
bottom portion of an apertured cylindrical aglomerator exit wall. Grinding
balls,
bearing balls, rubber coated balls or a mixture of light balls, for example
golf balls,
and metal balls may be used for such bed of balls. Also spherical Jaeger Tr-
packs
(See Fig 6D) or stronger tower packings may be used as balls instead of golf
balls for
mixing with metal balls to form a bed of tumbling balls of suitable average
density.
The average density of the balls must be large enough that the bed will tumble
inside
the drum agglomerator in the presence of viscous bitumen at a desired
operating
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Mr. Jan Kruyer, P.Eng. Box 138 Thorsby, Canada TOC 2P0
temperature. However the average ball density must be low enough to prevent an
agglomerator drum to take on the weight of a ball mill. Hence, a agglomerator
drum
is not a ball mill but is of lighter construction. The bed of balls (including
voids
between the balls) may fill between 10 and 90 percent of the volume of the
drum,
depending on the shape of the agglomerator and on the desired amount of
agglomeration desired. A bed of tower packings does not normally tumble inside
of a
drum filled with a bitumen containing mixture since the viscosity of bitumen
at
process temperature tends to prevents tumbling of light tower packings by
themselves. When not tumbling, tower packings rotate in unison with the
aglomerator walls and the suspension flowing through the tower packings comes
into
intimate contat with the surfaces of the tower packings as the suspension
passes
through the aglomerator compartment through the voids of the tower packings,
causing aglomeration of the bitumen particles of the suspension due to
temporary
adhesion to bitumen coated tower packing surfaces.
"agglomeration" refers agglomerating, which is to increasing the size of
bitumen particles in a continuous aqueous mixture by means of a drum
agglomerator
prior to the removal of enlarged bitumen particles from the mixture by an
oleophilic
apertured screen formed by adjacent cable wraps. When a bed of tumbling
oleophilic
balls is used in the drum, these balls agglomerate the bitumen and also knead
the
collected bitumen. This kneeding does not occur when, instead of tumbling
balls,
tower packings are used in the drum aglomerator that remain stationary with
respect
to the drum wall.
"aqueous phase" or water phase refers to water that may contain solids and
dispersed bitumen.
"bitumen phase" refers to bitumen that may contain dispersed water and
solids.
"bitumen removal zone" refers to a section along an apertured oleophilic
screen. In a bitumen removal zone, adhering bitumen phase is removed from the
screen surfaces to become the product of separation. In the present invention
the
screen surfaces are cable wrap surfaces.
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Mr. Jan Kruyer, P.Eng. Box 138 Thorsby, Canada TOC 2P0
"bitumen" refers to a viscous hydrocarbon that contains maltenes and
asphaltenes and is found originally in oil sand ore interstitially between
sand grains.
Maltenes generally represent the liquid portion of bitumen in which
asphaltenes of
extremely small size are thought to be dissolved or dispersed. Asphaltenes
contain
the bulk of the metals of bitumen and probably give bitumen its high
viscosity. In a
typical oil sands plant, there are many different streams that may contain
bitumen
particles that have disengaged from the sand grains. These streams may, but do
not
have to contain sand grains. Asphaltenes may be removed from bitumen by
dissolving bitumen in straight chain hydrocarbons, resulting in precipitation
of
asphaltenes.
"bitumen product" or "raw bitumen" both refer to bitumen originally
derived from an oil sand deposit and may be the raw uncleaned bitumen product
of
separating oil sand slurry from mined oil sand ore, may be the raw bitumen
product of
in situ bitumen production, may be the raw bitumen product of separating oil
sand
tailings pond sludge (fluid tailings) or may be the raw bitumen product
derived from
processing an intermediate process stream of an oil sands plant. The raw
bitumen
may be obtained by means of an oleophilic apertured screen, by means of
bitumen
froth flotation or by in situ methods. Bitumen froth obtained by means of
bitumen
froth flotation contains air. Bitumen obtained by screening with an apertured
oleophilic screen normally does not contain much air.. In the present
invention it can
be advantageous to heat the bitumen product before it is recovered in a
bitumen
removal zone. Such heating may be done, for example, by sparging live steam
into
the bitumen product after it leaves a separation zone and moves towards a
bitumen
removal zone, or when bitumen is removed in a bitumen removal zone. One nice
feature of the separator design of Figure 4A is that either or both rollers
(41 and 42)
may be filled with flowing cold water to cool the cable wraps, heated as a
result of
prior steam sparging of adhering bitumen, before these wraps return to the
separation
zone.
"bitumen recovery" or "bitumen recovery yield" refers to the percentage of
bitumen removed from an original mixture or composition. Therefore, in a
simplified
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Mr. Jan Kruyer, P.Eng. Box 138 Thorsby, Canada TOC 2P0
example, a 100 kg mixture containing 45 kg of water and 40 kg of bitumen where
38
kg of bitumen out of the 40 kg is removed, the bitumen recovery or recovery
yield
would be a 95%.
"cable" refers to a non metalic rope, a metal wire rope, a single wire, a
monofilament or a multistrand filament rope.
"cable wraps" refers to the wraps of endless cable wrapped around two or
more rollers where the spaces between sequential cable wraps form apertures
through
which aqueous phase can pass, giving up most of its bitumen content to the
wraps as
it passes through the wrap apertures.
"conditioning" in reference to mined oil sand is consistent with conventional
usage and refers to mixing a mined oil sand with water, air and caustic soda
to
produce a warm or hot slurry of oversize material, coarse sand, silt, clay and
aerated
bitumen suitable for recovering bitumen froth from said slurry by means of
froth
flotation. Such mixing can be done in a conditioning drum or tumbler or,
alternatively, the mixing can be done as it enters into a slurry pipeline
and/or while in
transport in the slurry pipeline. Conditioning aerates the bitumen for
subsequent
recovery in separation vessels by bitumen froth flotation. Likewise, referring
to a
composition as "conditioned" indicates that the composition has been subjected
to
such a conventional conditioning process.
"confined" refers to a state of substantial enclosure. A path of fluid may be
confined if the path is, e.g., walled or blocked on a plurality of sides, such
that there is
an inlet and an outlet, and the flow is controlled to some degree by the shape
of the
confining material, enclosure or housing. Confined path refers to a path that
is
confined by an enclosure. For example, a fluid flowing in a pipe is confined
by the
walls of the pipe.
"cylindrical" as used herein indicates a generally elongated shape having a
circular cross-section of approximately constant diameter. The elongated shape
has a
length referred herein also as a depth as calculated from a defined end wall.
"endless cable" or "endless wire rope" is used in this disclosure to refer to
a
cable having no beginning or end, but rather the beginning merges into an end
and
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Mr. Jan Kruyer, P.Eng. Box 138 Thorsby, Canada TOC 2P0
vice-versa, to create an endless or continuous cable. The endless cable can
be, e.g., a
wire rope, a non metallic rope, a carbon fiber rope, a single wire, compound
filament
or a monofilament which is spliced together to form a continuous loop, e.g. by
a long
splice, by several long splices, by 9 strand splices, or by welding or by
adhesion.
"enlarged bitumen" refers to bitumen particles that have been agglomerated
in an agomerator drum to form enlarged bitumen phase particles or bitumen
phase
fluid streamers for subsequent capture by an apertured oleophilic screen, for
example
by oleophilic cable wraps that form a screen without cross members.
"generally" refers to something that occurs most of the time or in most
instances, or that occurs for the most part with regards to an overall
picture, but
disregards specific instances in which something does not occur.
"fluid" refers to flowable matter. Fluids specifically includes water,
bitumen,
slurries, suspensions or mixtures, and combinations of two or more fluids. In
describing certain embodiments, the terms sludge, slurry, mixture, mixture
fluid and
fluid are used interchangeably, unless explicitly stated to the contrary. A
fluid may
also be a gas or a gas dissolved under pressure in water.
"mesh belt" refers to a revolvable flexible belt woven into a mesh belt and
spliced to make it endless. For example, a nomex mesh belt is commercially
available that is woven from strong artificial fibres, has cross members, and
is re-
enforced with thin strands of berylium copper wire woven in the fabric to keep
the
belt more rigid. Alternately polyesther monofilaments may be woven into a mesh
belt comprising long logitudinal strands of polyesther with shorter polyesther
filaments woven into the longitudinal strands to form cross members. The edges
of
such a belt may be heated to weld the cross members to the outer longetudinal
members. The monofilaments may be 1 to 3 millimeters in diameter and the
apertures may be between 0.5 and 2 square centimeters. When mesh belt are
used,
automatic tracking of the belt is required to keep the belt from running off
the belt
supports. Mesh belt functioned very well when the oleophilic sieve process was
used
in the pilot plant but did not stand up to long duration testing. Cable wraps
have
replaced mesh belts in more recent developments of the process.
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Mr. Jan Kruyer, P.Eng. Box 138 Thorsby, Canada TOC 2P0
"mineral particulate matter" usually refers to the mineral matter found in
bitumen and may include titanium ore particles, zirconium ore particles, sand
particles, silt particles and clay particles; and may include other components
including in silver, gold, aluminum, calcium, iron, potassium, magnesium,
sodium,
silica, titanium and zirconium in measurable quantity. Particle sizes may vary
between less than 2 microns and up to 1000 microns. Bitumen product obtained
from
separating a tailings pond sludge (fluid tailings) by means of an apertured
oleophilic
screen or sieve was found to be high in rutile ore mineral particulate matter,
which is
a premium ore of titanium.
"multiple wraps of endless metal cable" or "multiple wraps of endless
plastic rope" refers to a revolvable endless belt without cross members formed
from
metal or plastic rope. Tracking is not required since the wraps are guided by
grooves
in rollers and/or by the spaces between hoops of apertured drum surfaces.
However,
when multiple wraps of single endless rope or cable are used, guide rollers
are
required to prevent the wraps from running off a supporting drum or roller.
"multiple wrap endless cable" as used in reference to separations
processing refers to a revolvable endless cable that is wrapped around two or
more
drums and/or rollers a multitude of times to form an endless belt having
spaced cables
and no cross members. Proper movement of the endless belt can be facilitated
by at
least two guide rollers or guides that prevent the cable from rolling off an
edge of the
drum or roller and guide the cable back to the opposite end of the same or
other drum
or roller. Apertures of the endless belt are formed by the slits, spaces or
gaps between
sequential wraps. The endless cable can be a single wire, a wire rope, a
plastic rope,
a compound filament or a monofilament which is spliced together to form a
continuous loop, e.g. by splicing, welding, etc. As a general guideline, the
diameter of
the endless cable can be as large as 3 cm and as small as 0.01 cm or any size
in
between, although other sizes might be suitable for some applications. Very
small
diameter endless cables would normally be used for small separation equipment
and
large diameter cables for large separating equipment. A multiwrap endless
cable belt
may be formed by wrapping the endless cable multiple times around two or more
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Mr. Jan Kruyer, P.Eng. Box 138 Thorsby, Canada TOC 2P0
rollers or apertured drums. The wrapping is done in such a manner as to
minimize
twisting of and stresses in the individual strands of the endless cable. An
oleophilic
endless cable belt is a cable belt made from a material that is oleophilic
under the
conditions at which it operates. For example, a steel cable is formed from a
multitude
of wires and the cross section of such a cable is not perfectly round but
contains
surface imperfections because of the warp of the individual wires. Bitumen
captured
by such a cable may at least partly fill the voids between the individual
wires along
the cable surface, and will remain captured there while the bulk of the
bitumen is
removed from the cable surface in a bitumen recovery zone. This residual
bitumen
keeps the cable oleophilic even after the bulk of the bitumen has been removed
from
the cable, and this remaining bitumen serves as a nucleus for capturing more
bitumen
in a separation zone.
"oleophilic" as used in these specifications refers specifically to bitumen
attracting. Most dry surfaces are bitumen attracting upon contact or can be
made to
be bitumen attracting. A plastic rope, or a metal wire rope normally is
bitumen
attracting upon contact and will capture bitumen upon contact unless the rope
is
coated with a bitumen repelling coating. A plastic rope or metal wire rope
that is
coated with a thin layer of bitumen normally is oleophilic or bitumen
attracting since
this layer of bitumen will capture additional bitumen upon contact. A plastic
rope or
metal wire rope will not attract bitumen when it is coated or partly coated
with light
oil since the low viscosity of the light oil will not provide adequate
stickiness for the
adhesion of bitumen to the rope. Similarly, a rope covered with a thin layer
of hot
bitumen will not be very oleophilic until the thin layer of bitumen has cooled
down
sufficiently to allow bitumen adhesion to the rope under the conditions of the
claimed
methods.
"oil sand bitumen product of separation" as used herein refers to any
bitumen product that results from processing an oil sand mixture by any method
including sieving of the mixture. The oil sand mixture may be a slurry of oil
sand and
water, it may be the tailings of separating an oil sand slurry, it may be the
middlings
of separating an oil sand slurry, it may be tailings pond sludge, it may be
bitumen
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Mr. Jan Kruyer, P.Eng. Box 138 Thorsby, Canada TOC 2P0
froth that has resulted from separating an oil sand slurry, or it may be the
bitumen in a
bitumen in water emulsion obtained from processing deep oil sand deposits by
means
of steam injection or oil sand formation combustion.
"oleophilic apertured wall" refers to oleophilic sieve, to oleophilic
apertured
screen, to oleophilic mesh belt, or to oleophilic endless rope or wire rope
cable
formed into an apertured oleophilic belt by means of wrapping the cable
multiple
times around rollers or drums. When using oleophilic apertured walls to
separate
bitumen from an aqueous mixture, water and suspended hydrophilic solids pass
through the apertures of the belt or through the slits between sequential
wraps of the
oleophilic endless cable, whilst bitumen and oleophilic solids are captured by
the
oleophilic belt surfaces or cable wrap surfaces in a separation zone. The
captured
bitumen is subsequently removed from these surfaces in a bitumen removal zone
to
become the bitumen product of separation. Mesh belts were used in the prior
art of
the inventor, but in many cases mesh belts did not last very long in the
presence of
abrasive sand. For that reason, mesh belts were replaced by endless plastic
rope belts
or metal wire rope belts, which made the technology more commercially viable.
Alternately the endless belts may be made from multiple wraps or single wraps
of
endless monofilament material, such as polypropylene, nylon, polyester or
similar
materials, spliced to make each monofilament endless.
"oversize solids" refers to any solids that are larger in size than the linear
distance between adjacent cable wrap surfaces and preferably refers to any
solids that
are in size about 10% of the linear distance between adjacent cable wrap
surfaces or
smaller. When such solids are abrasive, these may cause damage to the wraps.
Therefore, in many cases oversize also includes abrasive sand that may damage
cable
wraps. In case of a mesh belt, oversize was defined in relation to the size of
the mesh
apertures.
"residence time" refers to the time span taken for a mixture between entering
and leaving a system, a process, a vessel or an apparatus. It is assumed that
during
this time span the desired separation, compaction, settling or processing has
been
achieved.
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Mr. Jan Kruyer, P.Eng. Box 138 Thorsby, Canada TOC 2P0
"recovery" and "removal" of bitumen as used herein have a somewhat
similar meaning. Bitumen recovery generally refers to the recovery of bitumen
from
a bitumen containing mixture. Bitumen removal generally refers to the removal
of
adhering bitumen from the surfaces of a mesh belt or from the oleophilic wraps
of
endless cable. Bitumen is recovered from a mixture by an apertured oleophilic
screen
when bitumen is "captured" by the screen in a separation zone and adheres to
the
screen surfaces. Bitumen is stripped or removed from the screen surfaces in a
bitumen
removal zone. A bitumen recovery apparatus is an apparatus that recovers
bitumen
from a mixture.
"retained on" refers to association primarily via simple mechanical forces,
e.g. a particle lying on a gap between two or more cables. In contrast, the
term
"retained by" refers to association primarily via active adherence of one item
to
another, e.g. retaining of bitumen by an oleophilic cable or adherence of
bitumen
coated balls to bitumen coated internal walls of an agglomerator. In .some
cases, a
material may be both retained on and retained by an apertured oleophilic
screen.
roller" indicates a revolvable cylindrical member or a drum, and such terms
are used interchangeably herein.
"separation zone" refers to a section along an apertured oleophilic screen. In
a separation zone, bitumen adheres to the surfaces of the screen and aqueous
phase
generally passes through the apertures of the screen.
"tower packings" are light plastic extrusions, with large apertures, normally
used to provide oleophilic surfaces in extraction towers. When used in
rotating
bitumen agglomerators, the tower packings may completely fill the agglomerator
drum and the dispersion then flows through the apertures of the tower
packings.
Bitumen adheres to the oleophilic tower packing surfaces in increasing
thickness until
shear from the flowing dispersion strips enlarged bitumen from the packing
surfaces.
Jaeger Tr-Packs typically are spherical plastic tower packings that have a
very high
open area, and are very light. These tower packings are well suited for use in
bitumen
agglomerators when tumbling balls are not desired, or may be used as balls in
a
mixture of balls. A mixture of Jaeger Tr-packs and heavier balls may form a
bed of
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Mr. Jan Kruyer, P.Eng. Box 138 Thorsby, Canada TOC 2P0
tumbling free bodies in an agglomerator drum, free bodies being bodies that
will
tumble in a rotating drum in the presence of a suspension containing bitumen
particles. In that case Jaeger Tr-packs are considered to be balls.
"screen" refers to an apertured wall, sieve or cable belt. Apertures of a
wall,
of a screen or of a sieve are the holes or slits through which aqueous phase
can pass.
"schematic view" refers to a simplified drawing showing only the pertinent
features to explain its operation.
"sieve" refers to an apertured oleophilic screen and is used interchangeably
with "screen" unless specifically stated to the contrary. However, a screen
may also
be used to remove oversize particulates and in that case may not be oleophilic
and is
not a sieve as defined in these specifications. In prior patents of the
present inventor
the term "sieve" referred specifically to mesh belts, to metal conveyor belts
or to
perforated metal drum walls from which bitumen product was scraped or removed.
In the currently pending patent applications of the inventor the term "sieve"
more
specifically refers to screens formed from multiple adjacent wraps of endless
rope,
since mesh belts, apertured drum walls and commercial metal conveyor belts
were
found to performed poorly or wore out during long term separation of bitumen
from
aqueous mixtures. For that reason the term "screen" is used in preference to
"sieve"
in these specifications to indicate the difference between current and prior
art.
"single wrap endless cable" refers to an endless cable which is wrapped
around two or more cylindrical members in a single pass, i.e. contacting each
roller or
drum only once. Single wrap endless cables do not require a guide or guide
rollers to
keep them aligned on the support rollers but may need methods to provide cable
tension for each wrap. This is particularly so when sequential cable wraps are
of the
exact same lengths. In that case the wraps preferably are made from from
stretchable
material, such as nylon, or the cable may be designed to be stretchable and
provide
suitable tension in each wrap. Single wrap endless cables may serve the same
purpose
as multiple wrap endless cables for separations. When multiple wrap endless
cables
are specified, single wrap endless cables may be used in stead unless
specifically
excluded.
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Mr. Jan Kruyer, P.Eng, Box 138 Thorsby, Canada TOC 2P0
"sludge" as used herein refers to any mixture of fine solids in water and
contains residual bitumen. In describing or claiming certain embodiments, the
term
sludge, fluid tailings, fine tailings, mature fine tailings, bitumen
containing
suspensions and mixture are used interchangeably, unless explicitly stated to
the
contrary. In the oil sands industry, sludge is a term that used to be reserved
for a
mixture of bitumen and dispersed solids in a continuous water phase in a mined
oil
sands tailings pond but more recently "fluid tailings", "fine tails", "fresh
fine tails" or
"mature fine tails" have come in vogue for political reasons and also to
provide a
distinction as to how long this sludge has resided in a tailings pond.
"slurry" as used herein refers to a mixture of solid particulates and bitumen
particulates or droplets in a continuous water phase In the oil sands
industry, oil sand
slurry is a term normally used to describe an oil sand ore that has been or is
in the
process of being digested with water to disengage bitumen from sand grains. A
process aid normally is used when a slurry is produced for subsequent bitumen
froth
flotation. When a slurry is produced for separation by an oleophilic sieve, a
process
aid may not be required, or a different process aid may be used.
"sparging" or "sparged" as used herein refers to the introduction of a gas,
such as steam, carbon dioxide or other gas under pressure into a bitumen
containing
mixture or into fluid tailings or effluents through tubes, pipes, enclosure
openings,
perforated pipes or porous pipes. The type of gas used for sparging normally
is
described in the specifications. When steam is the sparging gas it may be used
to
increase the temperature of bitumen to reduce its viscosity. Live steam may
also
serve to both heat bitumen and to add water to bitumen.
"substantially" refers to the complete or nearly complete extent or degree of
an action, characteristic, property, state, structure, item, or result. For
example, an
object that is "substantially" enclosed would mean that the object is either
completely
enclosed or nearly completely enclosed. The exact allowable degree of
deviation
from absolute completeness may in some cases depend on the specific context.
However, generally speaking the nearness of completion will be so as to have
the
same overall result as if absolute and total completion were obtained. The use
of
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Mr. Jan Kruyer, P.Eng. Box 138 Thorsby, Canada TOC 2P0
"substantially" is equally applicable when used in a negative connotation to
refer to
the complete or near complete lack of an action, characteristic, property,
state,
structure, item, or result.
"surface speed" is the speed of movement of the surface of an apertured
agglomerator outlet or is the speed of movement of an apertured oleophilic
screen.
"velocity" as used herein is consistent with a physics-based definition;
specifically, velocity is speed having a particular direction. As such, the
magnitude
of velocity is speed. Velocity further includes a direction. When the velocity
component is said to alter, that indicates that the bulk directional vector of
velocity
acting on an object in the fluid stream (liquid particle, solid particle,
etc.) is not
constant. Spiraling or helical flow-patterns in a conduit are specifically
defined to
have changing bulk directional velocity.
"wrapped" or "wrap" in relation to a monofilament, wire, rope or cable
wrapping around an object indicates an extended amount of contact. Wrapping
does
not necessarily indicate full or near-full encompassing of the object.
As used herein, a plurality of components may be presented in a common list
for convenience. However, these lists should be construed as though each
member of
the list is individually identified as a separate and unique member. Thus, no
individual member of such list should be construed as a de facto equivalent of
any
other member of the same list solely based on their presentation in a common
group
without indications to the contrary.
Concentrations, amounts, volumes, and other numerical data may be
expressed or presented herein in a range format. It is to be understood that
such a
range format is used merely for convenience and brevity and thus should be
interpreted flexibly to include not only the numerical values explicitly
recited as the
limits of the range, but also to include all the individual numerical values
or sub-
ranges encompassed within that range as if each numerical value and sub-range
is
explicitly recited. As an illustration, a numerical range of "about 1 inch to
about 5
inches" should be interpreted to include not only the explicitly recited
values of about
1 inch to about 5 inches, but also include individual values and sub-ranges
within the
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Mr. Jan Kruyer, P.Eng. Box 138 Thorsby, Canada TOC 2P0
indicated range. Thus, included in this numerical range are individual values
such as
2, 3, and 4 and sub-ranges such as from 1-3, from 2-4, and from 3-5, etc. This
same
principle applies to ranges reciting only one approximate numerical value.
Furthermore, such an interpretation should apply regardless of the breadth of
the
range or the characteristics being described.
Bold text in the present disclosure is provided for convenience only.
MORE DETAILED DESCRIPTION OF THE FIGURES
Fig. 1. Is a flow diagram of a typical commercial oil sands plant using a PSV
(primary separation vessel) and a TORV (tailings oil recovery vessel). In this
drawing
the oil sand ore is mined and moved by large dump trucks to roller crushers
where the
ore is crushed to a size suitable for slurry transport. A cyclo feeder mixes
the crushed
ore with water and air and introduces the resulting mixture into a pipeline
for slurry
transport and to condition the oil sand ore to convert it into a slurry by
turbulent flow
in the pipeline Additional air may be introduced into the slurry along the
pipeline.
The amount of water added at the hydrocyclone is limited in order to produce a
thick
slurry that will contain entrained air. Flood water is then added to thin the
aerated
slurry for suitable froth flotation in a PSV. Residence time in the PSV
reportedly is
about 45 minutes for most oil sand slurries. Bitumen froth is skimmed from the
top.
Bottoms and middlings from the PSV are pumped to the TORV for recovering some
of the bitumen that would not float in the PSV. Bitumen froth rising to the
top of the
TORV is pumped to the PSV inlet and middlings from the TORV are hydrocycloned
to yield additional bitumen froth that is returned to the TORV. TORV tailings
and
hydrocyclone underflow are pumped through a slurry pipeline to a tailings pond
for
beach settling of coarse sand for building pond dykes and the resulting fluid
tailings
run off flow into the sedimentation area where these take a few years to
settle before
recycle water from the top of the pond can be used in the extraction plant.
After
settling the fines form thixotropic gels that will not dewater naturally.
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Mr. Jan Kruyer, P.Eng. Box 138 Thorsby, Canada TOC 2P0
Residence time in a TORV is not reported in current literature. It is
reasonable to
assume that total residence time in the PSV andf the TORV is at leasty 70
minutes.
Each commercial oil sands plant uses a different configuration but each uses
very
large separation vessels to encourage bitumen froth to rise to the top and to
maximize
bitumen froth recovery. Some use a PSC (primary separation cell) which has a
steeper cone than a PSV and some use subaeration cells in place of a TORV. In
subaerated cells, air is introduced into the middlings product of a PSV or PSC
by
means of rapidly rotating air spargers that introduce air into the bottom of
these cells
to scavenge for and float additional bitumen froth.
Pumps and sample ports are not shown in Figure 1 to keep it simple but
clearly much control is required in a current commercial oil sand extraction
plant to
optimize the flow and composition in all the various pipeline flow loops.
Figure 1 is
only one of several variations of the Clark process in commercial use.
Fig. 2. is a general flow diagram for processing mined oil sand by bitumen
agglomeration and screening. Several configurations are possible and one of
these is
illustrated in this Figure. As described in copending patent application CA
2,700,446
the equipment required for bitumen agglomeration and screening may be small
enough to allow oil sand extraction closer to the mine face than is feasible
with the
huge vessels of the current commercial plants. In Figure 2, oil sand is mined
and
crushed and then enters a high speed ablation drum. The older commercial oil
sands
extraction plants use conditioning drums, which are very large slowly turning
drums
to condition oil sand with water, caustic soda and air to make a thick aerated
slurry
suitable for flooding, followed by flotation in a PSV. In contrast, the
ablation drum
of the referenced copending application has high throughput capacity, is much
smaller and rotates fast in cateracting mode to form a diluted oil sand slurry
that
contains very little or no air and is ready for separation in a shorter time
than is
possible in the current commercial plants that required a thick aerated
slurry.
The dilute oil sand slurry is coarse screened to remove rocks and coarse
gravel
and then is pumped to a confined path hydrocyclone that is disclosed in detail
in
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Mr. Jan Kruyer, P.Eng. Box 138 Thorsby, Canada TOC 2P0
copending patent application CA 2,638,550. This hydrocyclone features a
confined
path in the form of a coiled pipe upstream of the hydrocyclone body. The
coiled pipe
is provided with nozzles in the outside lane for fluid injection to drive
dispersed
bitumen particles from the outside lane to the inside lane for reporting to
the
hydrocyclone overflow. The confined path hydrocyclone overflow enters a
rotating
agglomerator that features an apertured cylindrical wall that is partly
covered with a
revolving apertured oleophilic screen in the form of multiple adjacent cable
wraps. In
a separation zone debituminized slurry flows through the drum and screen
apertures
along the bottom of the agglomerator to become effluent whilst agglomerated
bitumen leaving the agglomerator through its apertured wall adheres to the
screen
cable wraps to be removed in a bitumen removal zone represented by two squeeze
rollers above the agglomerator. This is the raw bitumen product of separation
and
contains some water and solids but specifically contains ultrafine minerals.
In the
current commercial processes the ultrafines end up in the settling portions of
tailings
ponds and there form a thixotropic gell, which is the reason why current
commercial
fluid tailings after settling will not dewater in commerial tailings ponds.
Unlike the
current commercial plants that allow these ultrafines to report to the fluid
tailings, the
ability of agglomerating the ultrafines into the bitumen product prevents
these gel
forming ultrafines from entering tailings ponds, as described in copending
patent
application CA 2,696,181.
The underflow of the confined path hydrocyclone provides a filter bed for the
effluent leaving the agglomerator and allows water run off from the resulting
tailings
to return to the process for making more oil sand slurry. This water run off
may be
hydrocycloned to remove some of its solids before returning to the process,
and the
underflow of this conventional hydrocyclone may also be filtered by the sand
bed of
the confined path hydrocyclone. One nice feature of bitumen screening is that
the
process is very tolerant of fines in the process water. The left over solid
tailings
contain between 20 and 25% water and this creates a demand for some fresh
water for
slurry preparation. During winter time this fresh water may be hot water to
melt
frozen lumps of oil sand ore in the ablation drum.
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Mr. Jan Kruyer, P.Eng. Box 138 Thorsby, Canada TOG 2P0
Fig. 3A is a sectional view of a conditioning drum cut lengthwise. Feedstock
(1) enters the drum (2) through a rotary seal type entrance (3) and flows into
a bed (4)
of balls (5) contained in the drum (2). The drum has endwalls (6 and 7)
supported at
one end by a rotary turn table (8) on a structural mount (14) which turn table
allows
passage of feedstock through its centre. The drum (2) is supported at the
other end by
a shaft (10) in a bearing in a large pillow block (9) on a structural mount
(13). A
sprocket (11) mounted on the shaft (10) is mechanically coupled to a gear
motor (12)
by a roller chain. The two end walls (6 and 7) are connected to each other by
heavy
bars (15) that prevent sagging of the drum due to the weight of the bed (4) of
balls. A
number of these bars (15) are mounted concentric with the feedstock (1)
entrance (3)
and their number and size are calculated to suitably strengthen the drum (2).
Instead
of a series of bars (15), a rigid central pipe (not shown) may be used, which
contains
a few holes to allow feedstock (1) to flow to the bed (4) of balls. The
cylindrical wall
(16) of the conditioning drum is comprised of a large number of hoops (17)
that may
be assembled from cut sections of steel plate or that may be rolled from flat
bars.
These hoops have in internal diameter, an external diameter and a thickness.
In all
cases the thickness of each hoop is smaller in size than the difference
between the
hoop outside diameter and inside diameter. That is the reason why these are
called
hoops instead of rings. In many cases the hoop thickness is less than one
tenth of the
difference between hoop outside diameter and inside diameter. For example,
nominal
0.25 inch thick (6 mm), 4 inch wide (100mm) steel flat bars may be rolled into
hoops
that are 2 meters in inside diameter; the ends may welded together, and the
hoops (17)
may be re-rolled to make them truly round. Each hoop is welded at its inside
diameter to cross bars that are evenly spaced around the periphery of the drum
(2) and
these cross bars are attached to the end walls (6 and 7) of the drum (2) by
means of
attachment rings (201 and 202) In this manner the cylindrical wall (16) of the
drum
(2) is apertured, contains a bed (4) of balls (5) and allows exit from the
drum for
feedstock (1) after it has been processed. Oleophilic cable wraps (18) partly
fill the
spaces between adjacent hoops to partly block or reduce the size of the
aperture
openings of the drum and to capture bitumen phase. The workings of the drum
and of
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Mr. Jan Kruyer, P.Eng. Box 138 Thorsby, Canada TOO 2P0
the cable wraps are explained in more details with Figure 4. A enlarged cross
sectional view of a few hoops (17) welded to a cross bar (16) and with cable
wraps
(18) between hoops (17) is shown in Fig. 3B, which uses the same component
numbers as Figure 3A. Again referring to Figure 3A, a flanged opening (20) is
provided for the insertion or removal of balls (5) and the inside of the end
wall (6) is
kept smooth to prevent balls from getting caught in the flange opening (20).
Splash
baffles (21 and 22) may be provided under the drum. When the drum is short or
when the cross bars (16) are heavy, concentric bars (15) or concentric pipe
may not
be required, since the cross bars (16) welded to each hoop (17) inside
diameter, and
fastened to the end walls will provide considerable strength and rigidity to
the drum
(2).
Fig. 4A is a cros sectional view across the width of the drum of Figure 3A and
also shows revolving rollers and revolving cross bars covered by cable wraps.
Each
cable wrap (30) is in contact with many of the cross bars (31) Shown are the
feedstock entry (32) and the main strenghtening bars (33) that provide
rigidity to the
drum (34) and hoops (35) welded on the inside diameter (36) to cross bars (31)
that
keep the hoops properly aligned and spaced. Also shown are the splash baffles
(37)
and the flow of aqueous phase (38) out of the agglomerator in the separation
zone
(39). Shown also are the bitumen removal zone (40) consisting of two rollers
(41 and
42) that may be grooved and prevent any significant amounts of bitumen to pass
by
these rollers but causes the bitumen (43) to flow into a bitumen receiver (44)
that has
an exit pipe (45) for transporting the bitumen product away from the receiver
(44) by
means of a pump (not shown) Also shown are one of several nozzles (46) that
may be
used to spray water onto bitumen (not shown to keep the drawing simple)
adhering to
the cable wraps (47). The bitumen receiver (44) has optional baffles (48 and
49) to
heat the rising bitumen on the moving cable wraps. This heating is illustrated
by the
electrical resistance symbol (50). Heating may be done by sparging live steam
between these baffles ((48 and 49) into the rising bitumen. Couette flow of
cold
bitumen entering with the cable wraps into the space between the baffles (48
and 49)
will force the heated biutmen upward into the bitumen receiver, as indicated
by the
CA 02707577 2010-06-28
Mr. Jan Kruyer, P.Eng. Box 138 Thorsby, Canada TOC 2P0
curved arrow at the top of the left baffle (48). One nice feature of the
separator design
of Figure 4A is that either or both rollers (41 or 42) may be cooled, for
example by
water flowing through the roller interiors to cool down warm cable wraps
before
these leave the bitumen removal zone to return to the separation zone for
capturing
more bitumen.
A scraper blade (51) attached to the bottom receiver baffle (48) serves to
scrape bitumen from the hoop (34) surfaces and transfer it to to cable wraps
(30) as
these move upward to the bitumen removal zone (40). As described, the baffles
(48
and 49) are placed close to the cable wraps (31) to cause couette flow of
viscous
bitumen into the receiver (44) before this bitumen is contacted by live steam.
The top
baffle (49) may have edges adjacent to the outer cable wraps and may be angled
and
automatically adjusted with respect to distance to the cable wraps to enhance
the
desired couette flow of bitumen adhering to the cable wraps (30) and prevent
spilage
of bitumen. The force of gravity could cause warm excess bitumen to fall off
the
wraps (31) or flow downward along the wraps but the baffles contain this
excess
bitumen and, with colder, more viscous bitumen behind it, cause it to flow
upward
into the receiver due to couette flow. Thus, bitumen leaving the hoops (35) of
the
rotating agglomerator (34) are relatively cold and will tend to fill the space
between
the baffles(48 and 49). Positioning of these two baffles (48 and 49) and
control of
heating (50) therefore represent an important part of equipment optimization
and
adjustment.
Warm water or hot air may be provided instead of cold water from the nozzles
(46) to remove superficial mineral matter from the captured bitumen before it
is
removed in the bitumen removal zone, and alternately to preheat the captured
bitumen. However, care must be taken not to wash warm bitumen down the rising
cable wraps.
For an agglomerator rotating counter clockwise as in Figure 4A, feedstock
(53) enters the agglomerator (34) through its central inlet (32) and is
agglomerated by
a bed (54) of balls to increase the size of bitumen particles dispersed in the
feedstock
(53) by means of adhesion to oleophilic surfaces of the balls and subsequent
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Mr. Jan Kruyer, P.Eng. Box 138 Thorsby, Canada TOC 2P0
sloughing off of enlarged bitumen phase particles back into the mixture or for
temporary storage in voids of the bed (54) oof balls. Aqueous phase (38)
mainly
leaves through the left bottom quadrant (55) of the agglomerator wall, where
the
voids between wraps and hoops are not blocked by bitumen. Along the right
bottom
quadrant (56) of the agglomerator wall, bitumen being kneaded out of the ball
voids
due to the movement of the bed (54) of balls in the revolving agglomerator
(34) will
tend to fill the aperture voids between wrap and hoop surfaces (See Figure 3B
for a
close up sketch of the apertures) and will prevent or reduce the flow of
aqueous phase
(38) out of the agglomerator (34). Kneading by the bed (54) of balls will tend
to
cause bitumen phase to flow through the drum apertures in the right bottom
quadrant
(56) of the drum (34) and deposit a thick layer of bitumen (not shown) on the
cable
wraps for transfer to the bitumen removal zone (40) Splash baffles (37) may be
replaced by a tank to collect the effluent for transport to storage or
dewatering.
Fig. 4B illustrates a short section of the scraper (51) of Figure 4A. The
scraper (67) has teeth (65) that fit between the hoops to more effectively
scrape
bitumen from the hoops and deposit it on the cable wraps moving towards the
bitumen removal zone. Or in other words, the scraper of Figure 4B has adjacent
slits
(66) that accommodate adjacent hoops for proper transfer of bitumen from hoops
to
wraps.
Fig. 5A is similar to Figure 3A with two main differences. In Figure 5A the
agglomerator has two compartments. The first compartment (70) receives the
feedstock (71) and is filled with oleophilic tower packings (72) in a maner
that these
tower packings (72) are not free to tumble. From there the partly agglomerated
feedstock passes through an apertured wall (73) into a second compartment (74)
partly filled with a bed of tumbling balls (75) The cylindrical wall (76) of
the second
compartment (74) is similar in construction and operation as the apertured
cylidrical
wall of Figures 3 and 4 and is as described with these Figures. Another major
difference is that the agglomerator end walls (77 and 78) have slewing rings
(79) that
are supported on rollers (80) on shafts in bearings that are driven by a motor
(81). In
Figure 3A the drum was supported by amounted central bearing and by a vertical
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Mr. Jan Kruyer, P.Eng. Box 138 Thorsby, Canada TOG 2P0
central turn table bearing. When designing agglomerators supported by slewing
rings,
the endwalls normally are reenforced to prevent deformation. However, such
reenforcement is not shown here for the sake of simplicity.
Fig. 5B is very similar to Figure 5A with the exception that the first
compartment (90) is concentric with the second compartment (91) which two
compartments are separated by a perforated cylindrical sheet (92) that
increases the
hold up of mixture in the first compartment for feedstock agglomeration by
tower
packings before entering the second compartment (91) for agglomerating by a
bed of
balls.
Figs. 5C illustrate the potential locations of three sets of rollers (80) that
support the slewing rings of the rapidly rotating agglomerator. For simplicity
of
explaining the drawing, the rollers of Figures 5 A and 5B are positioned
according to
Figure 5C. However, the preferred position is shown by Fig. 5D which uses two
bottom rollers (98 and 99) to support the slewing ring. The top roller (97)
prevents
the rapidly turning agglomerator from jumping off the bottom rollers (98 and
99)
Fig. 6A is an illustration of a cateracting bed (100) of balls in a drum (101)
rotating at approximately 75 percent of critical drum rotation rate.
Fig. 6B is an isometric drawing of the drum (102) of Figure 5A, showing the
unapertured portion (103) of the drum wall, the apertured portion (104) of the
drum
wall, the rollers of the bitumen removal zone (105), the apertured oleophilic
screen
(106) in the form of adjacent cable wraps, the feedstock entrance (107) and
showing a
baffle plate (108) for directing effluent. It does not show drum supports or
drum
drive.
Fig. 6C is an illustration of a revolvable oleophilic screen in the form of
adjacent cable wraps (120) supported by grooved main rollers (121 and 122) and
with
cable guide rollers (123 and 124) that keep the endless cable from running off
the
main rollers (121 and 122). This concept was disclosed in detail in pending
Canadian
patent 2,638,596. The same type of endless cable, guide rollers, and adjacent
cable
wraps are used in the present invention. However, in the present invention one
of the
rollers is an apertured agglomerator drum and the other roller is one or both
of the
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Mr. Jan Kruyer, P.Eng. Box 138 Thorsby, Canada TOC 2P0
rollers of the bitumen removal zone. Since the concept of guide rollers to
keep
endless cables on rollers or drums has been described in detail in application
2,638,596 and is used in the present invention, there did not seem to be a
need to
explain this again. However, in all cases in the present invention a set of
guide rollers
is required for each endless cable unless each cable wrap is an endless cable
by itself.
In that case, each revolving cable wrap remains permanently between two
sequential
hoops as it revolves from separation zone to bitumen removal zone and back.
Then
the endless wraps all must be the same in length, and/or the wraps must be
made from
a stretchable material, such as nylon or from strechable cable or rope to
provide
proper wrap movement between the two zones and to prevent wrap slippage.
Fig. 6D is a photographic immage of a polyolefin Jaeger Tr-pack type of
tower packing that is spherical and may also be used on conjunction with and
be
mixed with metal balls in a bed of tumbling balls provided that the bed of
balls will
not crush nor destroy the Tr-packs. Similar tower packings may be designed and
fabricated that are of stronger design, or made from stronger materials and
may then
be used as replacements for Jaeger Tr-packs to serve the purpose of reducing
the
density of a mixed bed of balls in an agglomerator.
Fig. 7. shows a comparison between the rtequired size of a commercial PSC
(primary separation cell) plus subaeration cells for recovering bitumen from
7000
metric tons of oil sand ore per hour, and the required size of bitumen
agglomerators
and apertured screens for processing the same amount of ore per hour with the
same
degree of bitumen recovery. A typical commercial oil sand extraction plant
processing 7000 metric tons of mined oil sand uses a conical primary
separation cell
(PSC) that has a diameter of 30 meters and a height of 21 meters and a volume
of
about 7900 cubic meters to process approximately 10,300 cubic meters of slurry
per
hour, resulting in a PSC residence time of 46 minutes. The middlings from the
PSC
are processed in banks of 8 subearation flotation cells that have a combined
volume
of 1280 cubic meter. Assuming that 25 percent of the slurry flowing through
the PSC
volume are middlings, this will cause a flow of 2600 cubic meters of middlings
per
hour through subearation cellls that have a combined volume of 1280 meters.
The
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Mr. Jan Kruyer, P.Eng. Box 138 Thorsby, Canada TOC 2P0
resulting residence time in the subaeration cells then becomes 30 minutes and
the
total residence time through the PSC and the subaeration cells is 76 minutes
or more
than an hour and a quarter based on these data. In comparison, separating the
same
feedstock by means of agglomeration and sieving may only take 2.1 minutes
since the
flow rate is the same and the equipment volume is only 255 cubic meters.
Based on scale up calculations detailed in the previous pages, a 3 meter
diameter, 36 meter long agglomerator with associated apertured screen rotating
at 15
RPM is anticipated to separate 10,300 cubic meters of slurry per hour and with
the
same efficiency of bitumen recovery as the PSC and subaeration cells. Instead
of
using a single 36 meter long agglomerator, two 18 meter long agglomerators may
be
used. This comparison is illustrated in Figure 7. This suggests that an
oleophilic
sieve is 36 times as fast as froth flotation, which is remarkable. Even if it
turns out to
be only 10 times faster, this difference will have a huge impact on the future
of mined
oil sands extraction.
Six meter diameter agglomerators may be used instead of 3 meter diameter
agglomerators to reduce the width of the desired apertured screens, but then
the RPM
must be reduced to about 11 RPM to stay well below the cateracting RPM. In
that
case two agglomerators may be used that are 6 meters in diameter and are 12
meters
long. It is anticipated that increasing the drum diameter to 6 meters will
allow a
reduction in the percentage ball fill of an aglomerator to achieve the same
degree of
agglomeration as compared with a 3 meter diameter aglomerator.
The scale up factors presented here will need to be tested in the field with
very
large equipment and will require major R&D funding. However, the potential of
being able to reduce oil sand slurry processing time from about 76 minutes to
3 or
even 8 minutes will have a tremendous impact on the cost of commercial oil
sand
processing.
While these scale up calculations make emminent sense, it is obvious that
very larger scale test work is required to verify these data. It is not very
likely that
such large scale up test work will be attempted soon with oil sand slurries
since that
would interfere to a significant degree with the operation of a commercial oil
sands
CA 02707577 2010-06-28
Mr. Jan Kruyer, P.Eng. Box 138 Thorsby, Canada TOC 2P0
plant. However, the same scale up test work may be done with tailings pond
sludge,
or fluid tailings, as these are now called. Millions of cubic meters of fluid
tailings lay
in waste in the existing commercial oil sand tailings ponds. Performing large
size
scale up test work on fluid tailings will in no measure interfere with the
operation of a
commerial oil sands extraction plant. Not only will it produce a significant
amount of
bitumen that perhaps may be converted to asphalt for road construction but it
will also
clean up the tailings ponds by capturing the ultrafines that are the bad
actors which
prevent dewatering of fluid tailings.
Since oil sand slurries, after oversize removal, can be separated by an
agglomerator and associated apertured oleophilic screen with the same ease as
fluid
tailings, any scale up data obtained from processing fluid tailings may have
direct
application in commercial processing of oil sand slurries to produce bitumen
from
mined oil sand.
The average density of a bed of balls may vary from 1.5 gram per c.c. to 8
gram per c.c. depending on the feedstock composition, on the aglomerator
diameter
and on agglomerator ball loading. Normally the average density is less than 4
grams
per cubic centimeter to get agglomerators away from heavy ball mill designs.
The
ball diameter may vary in size but the average ball diameter of a bed of balls
normally
is between 1 centimeter and 10 centimeters. The thickness of the hoops may
vary
from 3 centimeters to 0.2 centimeters but the preferred range is between 1.5
centimeters and 0.5 centimeters. The distance between two adjacent hoops may
be
between 10 centimeters and 1 centimeter depending on the diameter of the cable
wraps selected to fit between the hoop surfaces and the thickness of the hoops
but the
preferred distance is between 6 centimeters and 1 centimeter.
SUMMARY
Pilot plant test work with oleophilic sieves and bitumen aglomerators has been
very successful. Mined high grade oil sand, medium grade oil sand, low grade
oil
sand, conventional middlings and tailings pond sludge or fluid tailings were
separated
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Mr. Jan Kruyer, P.Eng. Box 138 Thorsby, Canada TOC 2P0
in very simple equipment and achieved higher bitumen recovery than was
possible by
means of bitumen froth flotation in the curent commercial oil sands plants
that use the
process invented by Karl Clark over 80 years ago. The present inventor joined
the
Alberta Research Council in 1961 while Karl was still employed there as a
consultant.
As a result, he had access to and read all the research reports of Karl Clark,
who died
one year before the first commercial plant using the Clark process started oil
sand
processing. Kruyer was given permission to develop a process to overcome the
problems that had surface after the Clark process had been commercialized.
Instead
of attempting to improve the Clark froth flotation process, he chose a
different route
which involved sieving bitumen from suspensions. Only a few years prior to
that, the
Research Council of Alberta had given the Clark process to the industry for
free.
After a very successful start the Kruyer process was put on the shelf and the
inventor
was fired when he objected. The matter went to court for resolution and in a
consent
judgment the inventor was granted the right to continue development of his
process
on his own. In the years that followed he improved the oleophilic sieve
process and
was able to achieve more efficient bitumen recovery and faster separation
rates than
was possible with the Clark process. One major benefit was the discovery that
the
tailings of agglomeration and sieving will dewater rapidly. This in contrast
to the
commercial Clark process that produces fluid tailings that, after settling for
a few
years to 30 to 35 percent solids content, will not dewater naturally after
that. Another
significant discovery was that, while bitumen froth flotation of fluid
tailings from
tailings ponds was a failure, a suitable aglomerator and oleophilic sieve
combination
achieved very high bitumen recovery from such fluid tailings, and require very
simple
small equipment that featured high throughput. In other words, screening
bitumen
from a suspension turned out to be more efficient and much faster than
attaching air
bubbles to bitumen particles and waiting for these bitumen particles to rise
through an
aqueous sluny of settling sand and solids.
Several patents were granted originally for this process, but these were based
on the equipment that was developed in the pilot plant. For example, bitumen
agglomerators were patented that used perforated steel sheets for the
apertured
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Mr. Jan Kruyer, P.Eng. Box 138 Thorsby, Canada TOC 2P0
aglomerator cylindrical wall. While such patented aglomerators worked very
well in
the pilot plant, scaling these up to large commercial sizes became an
engineering
imposibility. These simply were not strong enough when extended to larger
sizes.
Similarly, endless mesh sieve belts were used in the pilot plant for
separating
suspension that contained agglomerated bitumen, water and mineral
particulates.
These mesh belts worked remarkably well in the pilot plant but did not last
for more
than a few months, and would have not lasted very long in a continuous
commercial
plant. As a result, an extensive development program was entered into to make
the
process suitable for scale up to the sizes needed for a commercial oil sands
plant.
As described, this technology uses a completely different approach, as
compared to conventionally accepted methods, to separate bitumen from
suspensions;
and covers a very broad field of engineering. As a result, the many copending
patent
applications referred to in the present invention, together with this present
invention,
cover a very broad, new and potentially very profitable field of engineering.
Unfortunately, during the past 50 years, much time and money have been
invested by
industry and governments on improving parts of the Clark process, and this has
resulted in many experts who are hesitant to look beyond the merits of the
Clark
process.
Thus, while many of the patents granted in the past had the objective of
improving the extraction of bitumen from aqueous suspensions on a pilot scale,
the
currently pending patent aplications are dedicated to making the process
commercially viable in a large scale industrial setting.
Of course, it is to be understood that the above described arrangements, and
specific examples and uses, are only illustrative of the application of the
principles of
the present invention. Thus while the nresent invention has been described
above
with particularity and detail in connection with what is presently deemed to
be
the most practical and preferred embodiments of the invention, it will be
apparent to those of ordinary skill in the art that numerous modifications may
be made without departing from the principles and concepts set forth herein.
38
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