Note: Descriptions are shown in the official language in which they were submitted.
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Mr. Jan Kruyer, P.Eng. Box 138 Thorsby, Canada TOC 2P0
POND SLUDGE BITUMEN AND ULTRA FINES
AGGLOMERATION AND RECOVERY
RELATED APPLICATIONS
This application is related to Canadian Patent application number 2,653,058
filed February 16`h , 2009 entitled "Dewatering Oil Sand Fine Tailings Using
Revolving Oleophilic Apertured Wall", Canadian Patent Application 2,647,855
filed January 15`h, 2009 entitled "Design of Endless Cable Multiple Wrap
Bitumen Extractors" and Canadian patent application number 2,638,596 filed
August 6th , 2008 entitled "Endless Cable System and Associated Methods", and
are referenced to by title in the present specifications.
FIELD OF THE INVENTION
The present invention relates to process devices and methods for processing
aqueous suspensions containing oil sand bitumen and discloses methods to
remove
ultrafines and bitumen from mature fine tailings, from fresh fine tailings,
from
middlings of an oil sands extraction plant and from any other aqueous
processed oil
sand stream that contains bitumen and mineral fines. Accordingly, the present
invention involves the fields of process engineering, chemistry and chemical
engineering.
In particular the present invention relates to Canadian Patent Application
entitled "Dewatering Oil Sand Fine Tailings Using Revolving Oleophilic
Apertured
Wall" in seeking to remove from fine tailings those components that prevent
fine
tailings dewatering. However, the present invention differs from this prior
application in several major areas. In particular, the present invention makes
use of
various cations in solution to cause bitumen phase to agglomerate with and
capture
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Mr. Jan Kruyer, P.Eng. Box 138 Thorsby, Canada TOC 2P0
montmorillonite nano particles and other fine particulates, which bitumen is
then
removed from the fine tailings by the use of an apertured oleophilic wall. The
prior
application, which was only filed a few months earlier, did not make claims
for the
use of cations. The present invention also discloses additional agglomeration
methods and equipment.
BACKGROUND OF THE INVENTION
A detailed description of oil sands, tar sands or bituminous sands deposits
and
of the processing of these ores to produce bitumen is provided in the above
referenced
patent applications. Some authors report that the Northern Alberta oil sands
resource
contains more than half of the remaining world oil reserves.
The Alberta oil sands 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. Only part of this ore can be mined economically. Current mining
methods
are not commercially viable when the ore is overlain by too much overburden or
when the oil sand layer is too thin or the ore is too lean to make overburden
removal
cost effective. About 10 percent of the oil sand ore can be mined but the
remainder is
covered with too much overburden. The ore contains approximately 84 weight
percent mineral solids and the remaining approximately 16 weight percent
comprises
bitumen and water. A high grade oil sand contains about 5 percent water and 11
percent bitumen or higher, and a low grade oil sand contains about 8 percent
water
and 8 percent bitumen or lower. Normally an oil sand ore containing less than
6
percent bitumen is not considered economical for processing especially. when
covered
by a thick layer of overburden. Low grade oil sands generally contain more
mineral
fines (silt and clay) and the associated connate water often is high in
divalent cations.
Low grade oil sands are more difficult to process than high grade oil sands.
Some oil
sand ores are found in estuary deposits, which ores usually are relatively
easy to
process by froth flotation, and some are found in marine deposits which are
more
difficult to process by current commercial flotation methods.
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Mr. Jan Kruyer, P.Eng. Box 138 Thorsby, Canada TOC 2P0
There presently are several commercial facilities near Fort McMurray which
extract bitumen from mined oil sands by the commercial Clark Hot Water
Extraction
Process which uses froth flotation to recover the bitumen. These are very
large
plants. For example, one plant per day mines at least 230,000 long tons of oil
sand
ore, uses 190,000 long tons of water, extracts 25,000 long tons of bitumen,
discharges
380,000 long tons of tailings, reclaims 120,000 long tons of tailings water
and rejects
12,000 long tons of oversize material. By the year 2006 three Alberta mined
oil sands
plants processed per day about one million long tons of oil sand ore to
produce more
than 700,000 barrels of bitumen per day.
In accordance with the first step of one commercial application of the Clark
process, the oil sand is mixed with hot water, air and a small amount of
"process aid"
(usually NaOH) to produce an aqueous slurry in which sand grains, fines,
bitumen
droplets and air bubbles are suspended in hot water. The oil sand slurry is
formed by
tumbling in a drum with hot water and process aid or by turbulent mixing of
ore with
water and process aid in a long distance pipeline. Flotation air enters the
slurry in the
drum or in the pipeline after which the slurry is diluted with additional
water and
introduced into a primary separation vessel known as a "PSV" where additional
air
may be required to cause bitumen droplets to attach to air bubbles and rise to
the top
of the vessel to be skimmed off as the "primary bitumen froth" product.
Process aid has a high pH and this serves to release from the ore carboxylic
(naphthenic) and sulfate/sulfonate detergents to allow for disengagement of
bitumen
from the sand grains,to provide the mineral surfaces in the slurry with a
strong
negative potential to disperse these minerals in the slurry, to encourage the
adhesion
of bitumen to gas bubbles, and to allow aerated bitumen to rise to the top of
separation vessels. The resulting aqueous phase pH in the Clark process
averages
about 8.5 . After operating for a while, the commercial oil sand plants limit
the use of
fresh water for processing oil sand ore by using a large amount of recycle
water from
its tailings ponds. This also reduces the amount of process aid required for
extracting
bitumen from oil sand ore since the recycle water usually contains residual
process
aid and detergents.
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Mr. Jan Kruyer, P.Eng. Box 138 Thorsby, Canada TOC 2P0
Most of the oil sand bitumen is recovered in the PSV and is skimmed off the
top as the "primary froth". The coarse sand, together with water, some fines,
some
bitumen, some process aid, and some surfactants, sink and leave the PSV
through a
bottom outlet. This stream is referred to as "primary tailings".
Some bitumen and some fines leave the extraction process with the primary
tailings, but most of the slurry fines and some bitumen in aqueous suspension
collect
in the mid section of the PSV. This suspension is removed from the PSV mid
section
in the form of an aqueous drag stream called "middlings" and is introduced
into a
series of induced air flotation cells. Here the middlings are contacted with a
flood of
minute air bubbles to cause a large portion of the residual bitumen to attach
to these
air bubbles and float to the top of the cells to be skimmed off as the
"secondary
bitumen froth" product. For most processed ores, secondary froth contains more
mineral matter than primary froth and makes up only a small portion of the
total
bitumen recovered. A tailings product, referred to as "secondary tailings",
leaves
from the bottom outlet of the flotation cells, is combined with the primary
tailings and
is sent to a tailings pond by pipeline. The secondary tailings contain water,
some
fines, some bitumen, some process aid, and some surfactants. In more recent
developments the tailings are processed further to recover additional bitumen.
The combined tailings are discharged onto the shore of a large tailings pond
with or without the use of hydrocyclones. Here the coarse sand grains are
deposited
on the beach, leaving a fluid suspension of bitumen, fine solids, process aid
and
surfactants. This fine mixture flows into the sedimentation portion of the
tailings
pond where mineral fines and residual bitumen settle. Some water is released
and
rises to the top of the tailings pond, and this water is used is recycle
water. The
process water used in the current commercial extraction plants consists of
about 10
percent fresh water from the Athabasca river and about 90 percent recycle
water form
the tailings ponds. This recycle water can contain up to about 2 percent
solids.
Higher solids contents tend to interfere with oil sands processing in the
Clark
process. Water containing a higher solids content remain in the ponds where
the
particulate minerals and bitumen suspension go through a sorting process and
slowly
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Mr. Jan Kruyer, P.Eng. Box 138 Thorsby, Canada TOC 2P0
settle until the settled suspension, called "fine tailings" or "tailings pond
sludge",
reaches a solids content of about 30 weight percent and a bitumen content of
about 2
weight percent. It is then called "mature fine tailings" which are thought to
form
microscopic card-house structures of clay due to the plate-like character of
the
electrically charged clay fines. These electric charges are the result of
process aid
additions to the original oil sand slurry.
Ultrafine mineral particles, bitumen and biwetted solids in the mature fine
tailings suspension accumulate into thixotropic gel structures that severely
limit
further settling of the mature fine talings. Some of these components are
believed to
form plugs that prevent the escape of water through the pores of the cardhouse
structures. Compacting of the sediment, after that, results from the combined
weight
of the accumulating sediment and from fine sand and silt settling into the
sediment
from above, and from wind blown sand from the tailings pond dykes raining down
into the pond. It has been suggested that coarse mineral particles, such as
sand, may
break through the existing card house or gel structures and open up dewatering
channels in the thixotropic sediment while the finer sand and silt particles
become
trapped in the gel, densify it, and provide assistance in its very slow
compaction.
This natural compacting is so slow that most estimates suggest hundreds or
even
thousands of years before mature sludge will reach consolidation.
Problems with the accumulation of settling oil sand fine tailings problem were
not realized until about a decade after the first commercial oil sand plant
started its
operation. Initially it was assumed that the tailings would settle by gravity
in the
tailings ponds into a solid material that could be covered effectively by sand
and
overburden for subsequent site remediation. The possibility of gel forming
structures
in uncompacted fluid oil sand tailings was not contemplated beforehand and
this
unexpected problem has resulted in decades and many millions of dollars of
research
devoted to try and eliminate the fluid tailings problem. This research is
still ongoing
and has resulted in a large number of master's theses, doctor's theses,
research
publications, and a number of patents. By the year 2009 about 700 million
cubic
meters of tailings pond sludge have accumulated and are stored in huge ponds.
This
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Mr. Jan Kruyer, P.Eng. Box 138 Thorsby, Canada TOC 2P0
sludge is toxic. For example, when 10% pond water is mixed with 90% fresh
water,
about 50% of fish entering and remaining in this water mixture will die within
96
hours. Furthermore, to put 700 million cubic meters of toxic sludge in
perspective:
this amount is sufficient to cover a two lane highway, 10 meters wide, up to
the
rafters of a 6 story building, 15 meters high, for 5000 kilometers all the way
across
Canada from Victoria to Halifax. Should one of the pond dykes ever break due
to
seismic activity it would devastate the surrounding landscape.
Research that has been conducted by universities and oil sands companies on
overcoming the fluid tailings problem has been exclusively devoted to
understanding
the mechanism of bitumen froth flotation and to overcome its problems. Much
research has been devoted to gaining an understanding of how to modify fluid
tailings, how to accommodate it, how to reduce the amount of fluid tailings
(sludge)
produced, or how to chemically treat the sludge in the hope of consolidating
it into a
solid mass for oil sand lease remediation. Great strides have been made in
understanding the physics, chemistry, mechanism and behaviour of fluid
tailings; but
no conclusive and satisfactory solution has yet been found. Confirmation of
this may
be found in published literature and in the fact that Syncrude Canada Ltd.,
the
company in the forefront of sludge research, is currently asking the Alberta
government for permission to expand its tailings pond.
SUMMARY OF THE INVENTION
Fluid tailings contain a wide range of particulates and several types of clay
but
only some of these particulates are the bad actors that prevent fluid tailings
compaction and dewatering and comprise only a small percentage of the fine
minerals
of the fluid tailings. Bitumen particles, bi-wetted articles and nano size
montmorillonite clay particles have the ability to block the release of water
from fluid
tailings (sludge) due to the formation of gels and plugs that are strong
enough to
prevent or reduce sludge compaction when left undisturbed in the tailings
ponds.
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Mr. Jan Kruyer, P.Eng. Box 138 Thorsby, Canada TOC 2P0
As an independent inventor I have developed an approach that uses bitumen
agglomeration in a tumbler with a bed of oleophilic balls to capture into the
bitumen
phase those small amounts of nano size montmorillonite clay particles and bi-
wetted
(mostly humic) particles that prevent fluid tailings dewatering. I remove
these bad
actors from the fluid tailings. Bitumen already present in the tailings ponds
is used to
capture these detrimental particulates. The resulting bitumen phase with its
captured
particulates is thereafter removed from the fluid tailings by means of an
apertured
oleophilic wall whilst the effluent passing through the wall apertures is sent
to a
tailings pond for more rapid settling, compaction and release of recycle
water.
In order to achieve more effective capture of nano-size clay and bi-wetted
particles by bitumen, I add approximately one half mole to two moles of a
multivalent
salt oxide, or hydroxide reagent to each 100 kilo grams of montmorillonite in
the
suspension in order to change the surface chemistry of the clay and bitumen
particulates and thereby encourage the adhesion of the ultra fine clay
particulates to
bitumen during kneading that takes place in the agglomeration process of a
bitumen
agglomerator. The multivalent chemical or reagent added can contain calcium,
magnesium, iron or aluminum ions. A proper selection of the reagent and its
dosage
is a function of the fluid tailings composition. Both the type and dosage of
reagent
are influenced by a desire to maximize the adhesion of particulate matter to
bitumen,
but also to optimize bitumen agglomeration while minimizing the accumulation
of an
undesirable amount or type of ions in the resulting effluent. For example,
this
effluent will produce clarified water when allowed to settle for some time and
this
clarified water may be used as recycle water in a commercial oil sands
extraction
plant, where a high concentration of chlorine in such plant recycle water may
result in
severe corrosion when oil sand bitumen is upgraded or refined. Similarly a
high
concentration of calcium and magnesium ions in recycle water may have a very
negative effect on bitumen recovery and froth quality during froth flotation
of mined
oil sands. Sulphate ions in sludge may result in the eventual release of
hydrogen
sulphide to the atmosphere. For that reason care is to be taken to choose a
suitable
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Mr. Jan Kruyer, P.Eng. Box 138 Thorsby, Canada TOC 2P0
reagent and a suitable dosage of that reagent for addition to the fluid
tailings (sludge)
in the process of the present invention.
Other reagents may be added to the sludge after processing before it is sent
to
a tailings pond for settling, compaction and released of process water for use
as
recycle in a commercial oil extraction plant. For example, the effluent from
processing sludge in an agglomerator may be sparged with carbon dioxide in the
effluent pipeline to produce precipitating calcium carbonate or magnesium
carbonate
and thereby reduce the accumulation of calcium or magnesium ions in the
subsequently released recycle water.
In order to do all this, the present patent discloses and claims a bitumen
agglomerator with an agglomerating capacity that is much larger than the
bitumen
agglomerators I have patented before. It also has a shape that is different
from my
prior bitumen agglomerators, and achieves more effective agglomeration.
The agglomerator is in the form of a revolving cone with a central inlet
at the perimeter of the base and an apertured cylindrical wall outlet at the
opposite
end. The cone is tilted about 90 degrees to provide a generally horizontal
central
revolving axis from inlet to outlet. Furthermore, the newly disclosed
agglomerator
may revolve at speeds that are not necessarily synchronized with the surface
speed of
an apertured oleophilic wall mounted around or below the apertured
agglomerator
outlet.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 a is a side view of an agglomerator of the present invention, showing a
central inlet and an apertured outlet. The agglomerator is supported by
slewing rings
mounted on the agglomerator external surface and supported by rollers mounted
on a
shaft in bearings to revolve the agglomerator with a geared motor (not shown).
FIG. lb is a small scale perspective view of the agglomerator vessel of FIG
1 a, showing the inlet and the apertured outlet and the conical shape of the
agglomerator with its slewing rings.
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FIG. 1 c is an illustration of balls tumbling in an agglomerator that revolves
well below the critical speed to prevent the formation of a cateracting bed.
FIG. 1 d is an illustration of balls tumbing in an agglomerator that revolves
below the critical speed but fast enough to achieve cateracting of the balls.
FIG. 2a shows a circular cross section of the agglomerator filled with a bed
of
balls and filled with a level of mixture.
FIG. 2b is a sectional view of the agglomerator through section A-A of FIG.
2a. It shows the conical shape of the agglomerator partly filled with balls of
various
diameters and with a level of mixture. The central inlet is shown, as well as
the
apertured cylindrical outlet. Note, that under the outlet is an apertured
oleophilic wall
but this wall is not in contact with the apertured agglomerator outlet, and
this
provides for an opportunity to allow the surface speed of the agglomerator
outlet to be
different from the surface speed of the apertured oleophilic wall.
FIG. 2c illustrates one method of feeding mixture into the agglomerator.
FIG. 2d illustrates the use of a funnel with a screen to provide feed to the
method of FIG. 2c. The screen is provided to prevent large particles, such as
tree
roots, helmets, bottles or other refuse from entering the aggomerator.
FIG. 2e illustrates another method of feeding mixture into the agglomerator.
In this case there are two flanges that include a rotary seal to allow feed to
flow from
a stationary pipe into the revolving agglomerator.
FIG. 2f illustrates that the balls of the agglomerator may comprise two
materials, for example a steel core and a rubber cover. Alternately the bed of
balls
may consist of a mixture of metal balls and plastic balls, and the metal balls
may be
made from steel or from brass or bronze or may have an oleophilic copper
coating.
FIG. 3a is a schematic drawing to illustrate the agglomerator with the exit
covered by an apertured oleophilic belt to serve as the separation zone while
a set of
squeeze rollers serve as the bitumen removal zone to allow bitumen to flow
into a
receptacle. In this case the agglomerator exit is in contact with the
oleophilic belt and
this requires that the agglomerator exit surface speed be the same as the
oleophilic
belt surface speed.
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FIG. 3b is a schematic drawing of two agglomerator exits mounted above a
single apertured oleophilic belt. The exits are not in contact with the belt
surfaces and
this allows for surface speeds of the agglomerator exits to be different from
the
surface speed of the belt. Note, that in both cases here, the apertured
oleophilic wall is
inclined to achieve more effective separation as disclosed and explained in
the
copending patent application entitled "Design of Endless Cable Multiple Wrap
Bitumen Extractors"
FIG. 4 is a flow diagram of a mixing vessel for mixing reagent with sludge
before it enters the agglomerator, which agglomerator is similar to the one
illustrated
in FIG. 2b. Using such mixing vessel ahead of the agglomerator allows for the
thorough mixing of reagent with sludge before contact is made with the balls
of the
agglomerator. For the sake of simplicity, the apertured oleophilic belt is not
shown
here but is assumed to be present to produce a bitumen product and an effluent
from
which at least part of the bitumen, bi-wetted particles and ultrafines have
been
removed.
DETAILED DESCRIPTION
Before the present invention is disclosed and described, 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
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.
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Mr. Jan Kruyer, P.Eng. Box 138 Thorsby, Canada TOC 2P0
Definitions
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.
"agglomeration" refers to increasing the size of bitumen particles in an
aqueous mixture by means of an agglomeration drum prior to the removal of
enlarged
bitumen particles from the mixture by an oleophilic apertured wall, such as a
sieve,
screen, belt or cable wraps. As bitumen agglomerates it captures oleophilic
mineral
particulates as well as bi-wetted particles which are partly oleophilic. It
also captures
ultrafine hydrophilic particulates when the chemistry of the aqueous phase
causes the
adhesion of these ultrafines to the bitumen surface upon contact. This may
occur
when the aqueous phase contains divalent cations or when the pH of the aqueous
phase becomes acidic. It also may occur when the particulates come in very
close
contact with a bitumen surface after electric surface charges have been
reduced. In
such cases the surface forces of repulsion can become forces of attraction.
"agglomeration drum" refers to a drum containing oleophilic surfaces that is
used to increase the particle size of bitumen particles in oil sand mixtures
prior to
separation, and to capture bi-wetted and ultrafine particulates in the bitumen
phase.
Bitumen particles flowing through the revolving interior of said drum, through
voids
between oleophilic balls, come in contact with oleophilic surfaces and adhere
thereto
to form a layer of bitumen of increasing thickness until the layer becomes so
thick
that shear from mixture flowing through the revolving drum causes a portion of
the
bitumen layer to slough off, and/or to flow to the exit of the agglomerator,
resulting in
bitumen particles that are larger than the original bitumen particles of the
mixture.
Bi-wetted and ultrafine particulates become part of the bitumen phase in the
agglomeration process when the aqueous phase is pre-conditioned to increase
attractive forces and reduce repulsive forces between these particles and
bitumen
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Mr. Jan Kruyer, P.Eng. Box 138 Thorsby, Canada TOC 2P0
while retaining repulsive forces between coarse hydrophilic silica sand, silt
and clay
particulates and bitumen. When a bed of oleophilic balls is used in the drum,
these
balls agglomerate the bitumen but also kneed the collected bitumen. This
kneeding
normally does not occur when tower packings are used in the drum that remain
stationary with respect to the drum wall. Such tower packings were sometimes
used
in the prior art of the inventor.
"oleophilic apertured wall" refers to oleophilic sieve, to oleophilic
apertured
screen, to oleophilic mesh belt, to drum with oleophilic apertured cylindrical
wall or
to oleophilic endless rope or wire rope cable formed into an apertured
oleophilic belt
by means of wrapping the cable multiple times around two or more 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 drum,
or belt
or through the slits between sequential wraps of the oleophilic endless cable,
whilst
bitumen and oleophilic solids are captured by the oleophilic drum or belt
surfaces or
cable wraps. The captured bitumen and oleophilic solids are subsequently
removed
from these surfaces, along with some entrained water and entrained hydrophilic
solids
to become the bitumen product of separation.
"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. Finely dispersed and partly hydrophilic asphaltenes also are
thought of
as being one of the residual components in sludge that prevent or reduce
sludge
dewatering. Asphaltenes make up part of an agglomerated bitumen product
collected
by an apertured oleophilic wall.
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Mr. Jan Kruyer, P.Eng. Box 138 Thorsby, Canada TOC 2P0
"bitumen recovery" or "bitumen recovery yield" refers to the percentage of
bitumen removed from an original mixture or composition. Therefore, in a
simplified
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 some or most of its bitumen content to
the
wraps as it passes through the apertures.
"central location" refers to a location that is not at the periphery. In the
case
of a pipe, a central location is a location that is neither at the beginning
of the pipe nor
at the end point of the pipe and is sufficiently remote from either end to
achieve a
desired effect, e.g. washing, slurry preparation, disruption of agglomerated
materials,
heating of bitumen on cable wraps, etc.
"coagulant" as used herein refers to a chemical, a suspension or a solution of
a
chemical which when mixed with sludge or when mixed with a precursor of sludge
reduces the electrical charges of the particles in the sludge or in its
precursor.
"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 flotation. Likewise, referring to a
composition as
"conditioned" indicates that the composition has been subjected to such a
conditioning process.
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"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.
"couette flow" refers to laminar flow of a viscous fluid in the space between
two or more parallel or nearly parallel surfaces, one of which is moving
relative to the
other surfaces which are stationary. The flow is driven by virtue of viscous
drag force
acting on the fluid due to the moving surface, in cooperation with or against
any
pressure gradient parallel to the surfaces. Couette flow illustrates shear-
driven fluid
motion. The moving surface may be a mesh belt or multiple cable wraps and the
stationary surfaces may be the sides of a confined path enclosure. Revolving
endless
mesh belts or cable wraps coated with bitumen passing through a confined path
may
cause couette flow of bitumen due to the movement of the belt or of the
endless cable
wraps relative to the stationary walls of the enclosure. The stationary walls
may slow
down the flow of viscous bitumen through the confined path and allow the
accumulation of viscous bitumen to partly or completely fill a cross section
of the
enclosure.
"critical speed" is the speed of rotation of a drum in which the movable
contents of the drum adjacent to the interior drum wall remain in contact with
the
drum wall at all times due to centripetal force. For a conical drum critical
speed
computation of the drum is based on the largest internal diameter of the
conical drum.
"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 top or
side 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
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
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Mr. Jan Kruyer, P.Eng. Box 138 Thorsby, Canada TOC 2P0
or a monofilament which is spliced together to form a continuous loop, e.g. by
a long
splice, by several long splices, or by welding or by adhesion.
"enlarged bitumen" refers to bitumen particles that have been agglomerated in
an agomerating drum to form enlarged bitumen phase particles or bitumen phase
fluid
streamers for subsequent capture by an apertured oleophilic wall, for example
by
oleophilic cable wraps. Enlarged bitumen may contain captured solids.
"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, as used in the present invention
typically include a liquid, gas, and/or flowable particulate solids, and may
optionally
further include amounts of solids and/or gases dispersed therein. As such,
fluid
specifically includes slurries, suspensions or mixtures (continuous liquid
phase with
suspended particulates), flowable dry solids, aerated liquids, gases, 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.
"long splice" refers to a splice used in the marine and in the elevator
industry
to join the ends of ropes, wire ropes or cables to increase the available
length of such
ropes or cables or to make them endless while providing good strength in the
rope or
cable at the splice. The diameter of the rope or cable at a long splice
normally is not
much larger than the average diameter of the rope or cable itself.
"metallic" refers to both metals and metalloids. Metals include those
compounds typically considered metals found within the transition metals,
alkali and
alkali earth metals. Examples of metals are Ag, Au, Cu, Al, and Fe. Metalloids
include specifically Si, B, Ge, Sb, As, and Te. Metallic materials also
include alloys
or mixtures that include metallic materials. Such alloys or mixtures may
further
include additional additives.
"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
CA 02666025 2009-05-19
Mr. Jan Kruyer, P.Eng. Box 138 Thorsby, Canada TOC 2P0
rollers a multitude of times to form an endless belt having spaced cables.
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 rollers. 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 a cable is not
perfectly
round but contains surface imperfections because of the wraps 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 bitumen serves as a nucleus for
attracting
more bitumen in a separation zone.
"oleophilic" as used in these specifications refers to bitumen attracting.
Most
dry surfaces are bitumen attracting or can be made to be bitumen attracting. A
plastic
rope, or a metal wire rope normally is bitumen attracting 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
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Mr. Jan Kruyer, P.Eng. Box 138 Thorsby, Canada TOC 2P0
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.
"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 larger than 50% of the linear distance between adjacent cable wrap
surfaces.
Such solids tend to be abrasive and may cause damage to the wraps. In case of
a
mesh belt, oversize is similarly defined with respect to the size of the mesh
apertures.
"precursor" A precursor of sludge is any suspension from an oil sands plant
that eventually becomes part of the contents of a tailings pond or of a
tailings stream.
"residence time" refers to the time span taken for a mixture to leave a
system,
a process, a vessel or an apparatus after it has entered the system, process,
vessel or
apparatus. It is assumed that during this time span the desired separation,
compaction, settling or processing has been achieved.
"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 and bitumen removal generally refers to the removal
of
adhering bitumen from a mesh belt or from cable wraps of an endless cable.
Bitumen
is recovered from a mixture by an oleophilic sieve when bitumen is "captured"
by the
sieve in a separation zone and adheres to the sieve surfaces. Bitumen is
stripped or
removed from an apertured oleophilic wall 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
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Mr. Jan Kruyer, P.Eng. Box 138 Thorsby, Canada TOC 2P0
coated balls to bitumen coated internal walls of an agglomerator. In some
cases, a
material may be both retained on and retained by cable wraps.
"roller" indicates a revolvable cylindrical member or a drum, and such terms
are used interchangeably herein.
"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.
"sieve" refers to an apertured wall and is used interchangeably with "screen"
unless stated otherwise. For example, a screen may be used to remove oversize
particulates and in that case may not be oleophilic.
"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 when sequential cable wraps are of different lengths.
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.
"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. These
various
terms are used by various organizations and authors and often have the same
meaning
unless specifically defined. For example, sludge leaves the impression of
something
dirty and unattractive, whereas the term fine tailings has much more appeal to
the
human mind, similar to fine wine.
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Mr. Jan Kruyer, P.Eng. Box 138 Thorsby, Canada TOC 2P0
"slurry" as used herein refers to a mixture of solid particulates and bitumen
particulates or droplets in a continuous water phase It normally is 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.
"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 is
generally 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. Carbon dioxide may be
sparged into an effluent or into a suspension to change the chemistry of the
suspension. When a suspension contains multivalent cations, for example
calcium
ions, sparging the suspension with carbon dioxide may cause the calcium to
react
with the sparged carbon dioxide to form calcium carbonate precipitates, and
thus
remove calcium ions from the suspension. This is of importance when suspension
water is recycled to an extraction process that has little tolerance for
calcium ions.
"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
"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
wall.
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Mr. Jan Kruyer, P.Eng. Box 138 Thorsby, Canada TOC 2P0
"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 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
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.
CA 02666025 2009-05-19
Mr. Jan Kruyer, P.Eng. Box 138 Thorsby, Canada TOC 2P0
Bold headings in the present disclosure are provided for convenience only.
SUSPENSIONS SUITABLE FOR PROCESSING
The objectives of the present invention is to remove from or to prevent the
accumulation of gel forming of ultrafines and bi-wetted mineral particulates
in
tailings pond sludge (tailings pond sludge having various names which include
fluid
tailings, fine tailings, mature fine tailings, etc.) by using bitumen to
capture such
ultrafines and particulates However, several oil sand streams are precursors
that
contain residual bitumen and contain ultrafines and/or bi-wetted particulates
which
eventually report to a tailings pond. Examples of such precursors include:
1) The fluid run off when oil sand tailings are deposited on the shore of a
talings pond.
2) Fluid tailings that have resided in a tailings pond for less than a year.
3) Fluid tailings that have resided in a tailings pond for more than a year.
4) Fluid tailings that have resided in a tailings pond for decades
5) Fluid tailings from subaeration flotation cells which currently are mixed
with primary tailings from a PSV before the combined tailings are pumped to
a tailings pond.
6) Middlings from a PSV.
7) Overflow from hydrocyclones when combined tailings are separated into
underflow and overflow.
8) Fluid streams from thickeners that separate tailings into aqueous streams
that contain coarse minerals on the one hand and fine minerals on the other
hand.
9) Aqueous streams that result from the clean up of bitumen froth, such as
streams from dilution centrifuging and from paraffinic bitumen clean up after
light hydrocarbons have been removed from such streams.
10) Any other aqueous oil sand plant streams that contain fines and bitumen.
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Mr. Jan Kruyer, P.Eng. Box 138 Thorsby, Canada TOC 2P0
In summary, all oil sand streams that contain fines and bitumen may be
considered suitable candidates for processing by the apparatus and methods of
the
present invention. Additional bitumen may be added to such a stream if the
original
bitumen content of the stream is inadequate to remove the desired amount of
gel
forming ultrafine particles and bi-wetted particles. Tailings ponds often
contain
bitumen mats that have separated from the sludge but remain suspended in the
tailings ponds. Such bitumen mats are good candidates for augmenting the
bitumen
supply when needed in the present invention.
It is the objective of the present invention to speed up sludge compaction, so
that less time is required before suitable oil sand lease remediation can
start without
leaving behind a landscape that is marred by huge bodies of toxic aqueous
suspensions covered by a superficial layer of water.
THE NATURE OF SLUDGE FINES
In the current tailings ponds the fluid tailings or sludge contain a huge
amount
of clay. This clay includes kaolinite which has a low shrink-swell capacity
when
mixed with water and has a low cation cation exchange capacity (1-15 meq/100g.
based on dry weight of clay) when ions are added to the suspension water. It
includes
illite which has a low shrink-swell capacity and a low cation exchange
capacity (20 -
meq/100 g.). It also includes montmorillonite which is a swelling clay that
has a
high cation exchange capacity (60 - 120 meq/100g). Montmorillonite is
considered
largely responsible for gel formation in oil sand sludges. It has a very large
surface
area because it has a layered structure. This makes montmorillonite highly
adsorbent,
25 especially for polar molecules. When montmorillonite comes in contact with
water, it
absorbs the water and swells up.
Montmorillonite's water content is variable and the clay particles increase
greatly in thickness when these absorbs water. The surface area of dry
montmorillonite clay is very large because the clay platelets are very-thin
and very
30 small, and amount to about 70 square meter per gram based on dry weight
when the
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Mr. Jan Kruyer, P.Eng. Box 138 Thorsby, Canada TOC 2P0
external particle surface is considered only. When the internal accessible
particle
surface is considered, the particle surface of montmorillonite is about 800
square
meters per gram dry weight. That area is larger than several football fields
per gram
of clay. Such a huge particle surface has a major impact on the jell forming
ability of
montmorillonate clay in water in the presence of cations. While kaolinite and
illite
can also have very small particles, the montmorillonite particles appear to be
the
major causes of jell formation in tailings pond sludge. As an example of the
difference in surface activity of two clay types, one gram of montmorillonite
absorbs
about 10 milligrams of calcium in 5 minutes from a 1 millimole calcium
solution
while one gram of fine kaollinite with a similar average particle size as the
montmorillonite adsorbs about 1.5 milligram of calcium in 500 minutes.
Specifically, montmorillonite is a layered silicate mineral with crystals that
consist of three layers: a silicon tetrahedron, an aluminum octahedron, and
another
silicon tetrahedron. The unit structure is a very thin platelet about 1
nanometer thick
and 100 to 1000 nanometers wide and long, with a negative charge on the flat
surfaces. This negative charge may be neutralized by an interlayer of cations.
The
bonding strength between the negative charge on the surfaces and the
interlayer
cations of montmorillonite is low. Therefore, when montmorillonite is in
contact with
a solution containing another ion, the interlayer cations and in-solution
cations are
exchanged fairly rapidly with each other, especially when the pH of the
solution is 6
or more. The surfaces of montmorillonite platelets are negatively charged, and
the
edges are positively charged. Since opposite charges attract, when
montmorillonite is
dispersed in water, the platelets bond together electrostatically to form a
house-of-
cards structure and the liquid becomes viscous. When this structure develops
further,
the montmorillonite-dispersed liquid becomes a gel that can include the total
volume
of a tailings pond sludge. When stirring or shearing the mixture, the gel
temporarily
returns to a dispersed liquid since it is thixotropic. It appears that
shearing and
kneading an aqueous mixture, that contains montmorillonite, bitumen and
multivalent
cations in a bed of oleophilic balls, result in physical and chemical
reactions that
bond montmorillonite ultrafine particulates with bitumen and captures these in
the
bitumen phase.
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Mr. Jan Kruyer, P.Eng. Box 138 Thorsby, Canada TOC 2P0
Removing gel forming particles from sludge will improve sludge dewatering
in a major way. The present invention removes these particles by first adding
a
multivalent salt, oxide or hydroxide to the suspension being processed. The
suspension then enters a revolving bitumen agglomerator containing a bed of
oleophilic balls, which balls provide collection, agglomeration, shear and
mixing of
the bitumen phase with the mineral particulates to recover bitumen from the
aqueous
phase and to capture the adhering particulates into the bitumen phase. In a
bitumen
agglomerator, the oleophilic balls temporarily capture bitumen on their
surfaces,
knead the bitumen, and then release a portion of this bitumen back into the
mixture in
the form of enlarged bitumen phase particles that flow to the agglomerator
outlet. A
partial separation of the bitumen phase from the aqueous phase takes place in
the
agglomerator and this separation is mostly completed when the mixture leaves
the
agglomerator and passes through a revolving apertured oleophilic wall
(oleophilic
sieve). There the bitumen phase is captured by the surfaces of the oleophilic
wall in a
separation zone whilst aqueous phase effluent passes through the wall
apertures on its
way to a tailings pond or to further processing. The bitumen phase is removed
from
the wall surfaces in a bitumen removal zones and contains dispersed water
droplets
and mineral particulates. The concepts of bitumen agglomeration and the use of
apertured oleophilic walls is described in detail in the many patents granted
to the
present inventor and also in his currently pending patents. However, the
present
patent makes use of a new agglomerator design and of a method and operation
not
previously disclosed or claimed. While the present invention introduces a new
type
of bitumen agglomerator with a conical wall, other types of agglomerators
disclosed
and claimed previously by the inventor serve the same purpose but are not as
effective and efficient for the purposes of the present invention.
MORE DETAILED DESCRIPTION OF THE FIGURES
FIG. 1 a is a side view of an agglomerator of the present invention, suitably
supported to allow agglomerator rotation rates up to the critical speed
showing a
central inlet 100 and an apertured outlet 101. In this drawing the conical
agglomerator shell 104 is supported by slewing rings 102 and 103 mounted on
the
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Mr. Jan Kruyer, P.Eng. Box 138 Thorsby, Canada TOC 2P0
agglomerator shell 104 and supported by 4 rollers rollers 105, 106 (two other
rollers
not shown) mounted on shafts 107 in bearings 108 to revolve the agglomerator
shell
104 with a geared motor (not shown). The agglomerator outlet 101 is shown here
as
being covered by an endless multiwrap cable 130 which serves as the revolving
apertured oleophilic wall. When bearings are preferred in stead of slewing
rings
supported by rollers, one bearing and support may be mounted on the wall near
the
central inlet 100 concentrically with the inlet 100 and another bearing with
much
larger bore may be installed on the agglomerator shell 104 before or after the
apertured cylindrical outlet wall 101. Alternately, a smaller diameter bearing
may be
mounted concentrically on the solid endwall of the cylindrical outlet.
FIG. lb is a small scale perspective view of the agglomerator shell of FIG la,
showing the inlet 110 and the apertured outlet 111 and the conical shape of
the
agglomerator shell 109 with its slewing rings 112 and 113.
FIG. 1 c is an illustration of balls 114 revolving in the agglomerator shell
115
that revolves well below the critical speed of the agglomerator to prevent the
formation of a cateracting bed of balls 114. The critical speed is defined in
terms of
rotation rate as: RPM critical = 42.3 / Jd where d is the largest agglomerator
shell
internal diameter in meters. For example, an agglomerator shell that has a
maximum
internal diameter of two meters has a critical speed of 29.9 RPM and a shell
with a
maximum diameter of one meter has a critical speed of 42.3 RPM. Ball loading
and
adhesion between ball and shell wall due to bitumen have some impact on the
onset
of cateracting of balls in the agglomerator shell, and adhesion is influenced
by
bitumen temperature and solids content. Cataracting normally does not occur at
shell
RPM's below 55% of the critical RPM.
FIG. Id is an illustration of balls 117 tumbling in an agglomerator shell 116
that revolves below the critical speed but fast enough to achieve cateracting
of the
balls. Assuming that a shell RPM for cateracting turns at 75% of critical RPM,
it is
clear from the above critical RPM equation that in a conical agglomerator the
balls
may be cateracting in the large diameter portion of the shell but not
cateracting in the
smaller diameter portions of the shell. This is one of the features of the
agglomerator
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Mr. Jan Kruyer, P.Eng. Box 138 Thorsby, Canada TOC 2P0
of the present invention which allows for very thorough mixing of and intimate
contact between the feed and the balls near the entry of the agglomerator,
followed by
less violent mixing but more kneading of bitumen, clay and cation further down
the
length of the agglomerator before leaving though the apertured cylindrical
outlet.
FIG. 2a shows a circular cross section of the agglomerator shell 204 partly
filled with a bed of balls 203 and partly filled with a level of mixture 202.
The cross
section faces the agglomerator inlet 201 and a section line 200 is indicated
by A-A
which applies to line B-B of FIG. 2b The cross section shows the agglomerator
shell
204 through line B-B of FIG. 2b, the inlet 201, the large balls that reside
near the line
B-B and the mixture 202 being processed.
FIG. 2b is a sectional view of the agglomerator through section A-A of FIG.
2a. The dashed line B-B indicates the sectional location of FIG. 2a. FIG. 2b
shows
the conical shape of the agglomerator shell 205 partly filled with balls 206
of various
diameters and with a level of mixture 207. The central inlet 208 is shown, as
well as
the apertured outlet 209. Details for supporting apertured cylindrical
oleophilic
agglomerator walls are disclosed in the referenced copending patent
application
entitled "Design of Endless Cable Multiple Wrap Bitumen Extractors". An
apertured
oleophilic wall 210 in the form of multiple cable wraps is shown below the
apertured
outlet 208. The use of multiple cable wraps as the apertured oleophilic walls
are
disclosed in copending patent application entitled "Endless Cable System and
Associated Methods". Note, that the cable wraps 210 in FIG. 2b may not be in
contact
with the apertured agglomerator outlet 209 wall, and this provides for an
opportunity
to allow the surface speed of the agglomerator outlet 209 to be different from
the
surface speed of the apertured oleophilic wall 210. Thus this Figure
illustrates a
conical agglomerator shell partly filled with mixture and balls, where the
balls may be
cateracting near the entry of the shell, but not cateracting further down the
shell, and
with an outlet that deposits the processed mixture onto an apertured
oleophilic wall
that may or may not move at the same surface speed as the agglomerator outlet.
Cateracting may be beneficial for some mixtures, composition or temperature
conditions and not beneficial for others.
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The conical shape of the agglomerator shell achieves a sorting process when
various sizes of balls are used as shown in FIG. 2b. The large size balls tend
to
concentrate inside that part of the conical shell characterized by a
relatively large
shell diameter; the small size balls tend to concentrate inside that part of
the shell
characterized by a relatively small shell diameter, including the apertured
agglomerator exit. The intermediate size balls tend to concentrate in the mid
section
of the agglomerator. A bed of large balls has about the same percentage void
volume
as a bed of small or intermediate balls but the individual void sizes are
larger between
large balls than between small balls. Similarly, the voids between
intermediate size
balls are of an intermediate size. As a result, the permeability in the region
occupied
by the large balls is greater than in the region occupied by the intermediate
size balls
and is much greater than in the region occupied by the small balls. In fact,
cutting the
size of internal void dimensions by half reduces the permeability of a bed of
balls by
four, and cutting the size of internal void dimensions by four reduces the
permeability
of a bed of balls by sixteen. This change in permeability in a conical bitumen
agglomerator serves initially to provide very good acceptance of mixture into
the
voids between the large balls at the beginning section of the agglomerator
occupied
by large balls, followed by a progressively increased kneading as bitumen
progressively fills more of the ball voids. This exposes oleophilic bitumen
surfaces to
gel forming minerals as the mixture flows through the voids of progressively
smaller
balls towards the agglomerator outlet. The voids between the large balls
capture the
mixture entering the agglomerator and start the agglomeration process. The
smaller
voids between the progressively smaller balls knead the bitumen and
particulates and
transport the resulting bitumen phase towards the apertured cylindrical
agglomerator
outlet of the conical agglomerator. This mechanism prevents mixture from
simply
flowing overtop of the bed of balls to the agglomerator outlet.
FIG. 2c illustrates one method of feeding mixture into the agglomerator. In
this case a flexible hose 212 is connected to the agglomerator inlet 216 and
curves
upward to provide for mixture inlet that is above the agglomerator contents.
The hose
212 is connected with flanges 214 to a rigid pipe section 215 mounted in a set
of two
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Mr. Jan Kruyer, P.Eng. Box 138 Thorsby, Canada TOC 2P0
bearings 213 that keep the pipe section 215 in proper alignment, either
vertical or at a
slope.
FIG. 2d illustrates the use of a funnel 216 with a screen 217 to provide feed
218 to the rigid pipe section of FIG 2c. The revolving funnel conveniently
accepts a
feed without the need for a rotary seal and the screen 217 prevents large
particles,
such as tree roots, helmets, bottles or other refuse from entering the
aggomerator.
The set of bearings 220 of FIG. 2d are the same bearings 213 of FIG. 2c. An
optional
blade 250 may be used to remove debris from the revolving screen 217.
FIG. 2e illustrates another method of feeding mixture into the agglomerator.
In this case there are two flanges 221 that include a rotary seal to allow
feed to flow
from a stationary pipe 222 into the revolving agglomerator inlet 223.
FIG. 2f illustrates that the balls 230 of the agglomerator may comprise two
materials, for example a steel core 231 and a rubber cover 232. Alternately
the bed of
balls may consist of a mixture of metal balls and plastic balls (for example
golf balls),
and the metal balls may be made from steel or from brass or bronze or may have
a
copper coating to increase the oleophilicicity of the ball surfaces. Unlike a
ball mill, a
bitumen agglomerator does not grind the mixture particulates but adheres to
bitumen
of the mixture. It kneads bitumen and captures solids into the bitumen phase
in this
particular invention. For that reason, the balls of an agglomerator may have
resilient
surfaces that can absorb shock. Using such balls in a ball mill simply would
not grind
the ball mill charge of minerals but would leave the particulate matter mostly
unchanged in size. Unlike a ball mill, the objective of a ball charge in this
bitumen
agglomerator is to strip bitumen from a mixture and to knead the captured
bitumen.
The density of the bed of balls in an agglomerator must be high enough to
allow
release of the balls from the agglomerator drum wall before these balls reach
the top
of the agglomerator and to allow effective kneading of the mixture and its
bitumen
content. When the balls are too heavy the power required to turn the
agglomerator
may go up. The required optimum ball density is a function of ball loading in
the
agglomerator, of the RPM of the agglomerator, of the composition of the
mixture and
of the temperature of the mixture which control the viscosity and thickness of
the
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Mr. Jan Kruyer, P.Eng. Box 138 Thorsby, Canada TOC 2P0
bitumen layer adhering to the ball surfaces. Balls that are small in size have
a larger
surface area per mass than balls that are large in size and will have a
greater tendency
to stick to each other and to the upper portions of the revolving agglomerator
shell.
Consequently, small agglomerator balls may need to be heavier than large
agglomerator balls. As explained with FIG. 2f , the permeability of a bed of
small
balls is much lower than through a bed of large balls.
FIG. 3a is a schematic drawing to illustrate the agglomerator 301 with the
apertured cylindrical exit 302 covered for about 50 percent of its
circumference by an
apertured oleophilic belt 303 for the separation zone. A set of squeeze
rollers 304
provide the bitumen removal zone to allow bitumen to flow into a receptacle
305. In
this case the agglomerator exit 302 is in contact with the oleophilic belt 303
and this
requires that the agglomerator exit surface speed is the same as the
oleophilic belt
speed. Effluent flows into an effluent receiver 308.
FIG. 3b is a schematic drawing of two agglomerators with apertured
cylindrical exits 310 and 311 mounted above a single apertured oleophilic belt
312.
The exits 310 and 311 are not in contact with the belt 312 surfaces and this
allows for
surface speeds of the agglomerator exits 310 and 311 to be different from the
surface
speed of the belt 312. Sets of squeeze rollers 313 and 313 are used to remove
bitumen from the belt 312 and deposit this bitumen into bitumen receptacles
315 and
316 as effluent flows into effluent receivers 317 and 318. Besides squeeze
rollers, a
wide variety of methods for the removal of bitumen from apertured oleophilic
walls
have been disclosed and claimed in the above referenced patent applications.
The
belt under the agglomerator outlets is inclined in both cases to optimize
separation of
bitumen phase from aqueous phase as described in copending patent application
entitled "Design of Endless Cable Multiple Wrap Bitumen Extractors"
FIG. 4 is a flow diagram of a mixing vessel 401 for mixing reagent 402 with
sludge 403 or bitumen containing mixture before it enters the agglomerator
404,
which is shown here similar to FIG. 2b. Control valves 405, 406 and 407
monitor the
flow. Such a mixing vessel 401, using for example a revolving mixer 410 allows
for
the thorough mixing of reagent 402 with sludge or mixture 403 before the
combined
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Mr. Jan Kruyer, P.Eng. Box 138 Thorsby, Canada TOC 2P0
mixture 420 enters the agglomerator and contacts the balls of the agglomerator
404.
For the sake of simplicity, the apertured oleophilic wall is not shown here
but is
assumed to be present to produce a bitumen product 411 and an effluent 413
from
which at least part of the bitumen, bi-wetted particles and ultrafines have
been
removed. Carbon dioxide 412 may be sparged into the pipeline that transports
the
effluent to a tailings pond. This carbon dioxide 412 may serve to chemically
react
with residual multivalent cations to condition the effluent 411 so that water
released
in time from this effluent is low in multivalent cation content. For example,
the
carbon dioxide may react with calcium hydroxide in the effluent in a long
distance
pipeline to a pond and precipitate calcium carbonate in the tailings pond and
thus
remove residual calcium cations before recycle water of the pond is used for
processing oil sand ore.
The reagents used in FIG. 4 are coagulants that promote adhesion of fine
montmorillonite particulate matter to bitumen. Examples of such coagulants are
calcium or magnesium oxide, calcium or magnesium hydroxide, calcium or
magnesium sulphate, calcium or magnesium chloride, aluminum or iron based
coagulants or polymer based coagulants. To achieve the ability to add a
coagulant to
a mixture without diluting this mixture with too much water, the reagent may
be
supplied in the form of a finely dispersed aqueous suspension of the coagulant
or in
the form of a mud or paste. For example, milk of lime, which is a concentrated
suspension of calcium hydroxide in water, or a water wet paste of lime. Mixing
such
a reagent suspension or paste with fluid tailing very quickly makes the cation
available for reacting with the fluid tailings solids and bitumen. In pilot
tests for
separating very tight bitumen in water emulsions, using a bitumen agglomerator
and
an apertured oleophilic wall, the use of fine calcium sulphate suspended in
water
proved to be a very effective reagent for quickly breaking the emulsion and
recovering the bitumen. Any type of commercially available , and often
proprietary,
coagulant may be considered, provided the coagulants is inexpensive, works
well to
achieve the desired objective of capturing monymorillonite and will not have a
detrimental effect on any resulting recycle water used for froth flotation of
bitumen.
CA 02666025 2009-05-19
Mr. Jan Kruyer, P.Eng. Box 138 Thorsby, Canada TOC 2P0
The reagent should be inexpensive enough to be economically viable for use in
large
quantities and it should not do serious damage to processing equipment or
reduce
bitumen recovery or bitumen product quality of resulting recycle water for
froth
flotation. For example, when recycle water is used for processing additional
oil sand
in a commercial oil sands extraction plant, a high content of calcium or
magnesium
ions in the recycle water will have a negative impact on bitumen recovery and
bitumen product quality in the commercial froth flotation plant, unless
removed in
part. Similarly a high content of chlorine ions in recycle water may have a
corrosive
effect on equipment used in subsequent commercial processing of bitumen
product
because of residual chlorine ion content in water droplets carried by this
bitumen.
Bitumen product 411 of FIG. 4 produced by the revolving apertured oleophilic
wall of the present invention will contain a significant amount of very small
mineral
particulates which, if removed by dilution centrifuging could end up back in
the
tailings pond and essentially defeat the objectives of the present invention.
For that
reason the recovered bitumen 410 should either be discarded as landfill or
processed
by deasphalting with propane or higher molecular weight straight chain
hydrocarbons
or hydrocarbon mixtures to concentrate the fines with asphalt instead of
returning
dispersed fine particulates to the tailings pond that supplies recycle water
for froth
flotation.
There have thus been described various methods and units of equipment for
capturing gel forming fines from suspensions such as tailings pond sludge,
fluid
tailings , fine tailings or precursors of these suspensions. These methods and
apparatus units add multivalent cations to the suspension and then process
that
mixture in bitumen agglomerators with oleophilic balls to capture gel forming
suspension components into bitumen contained in these suspensions or into
additional
bitumen material added to these suspensions. In many cases, tailings ponds
contain
bitumen mats or bitumen lenses that have separated from the settling fines.
These
bitumen mats would provide a very suitable augmentation source of bitumen for
the
purposes of the present invention. Thereafter the agglomerated mixture is
passed
through an apertured oleophilic wall to separate it into an agglomerated
bitumen
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Mr. Jan Kruyer, P.Eng. Box 138 Thorsby, Canada TOC 2P0
phase product and into an aqueous phase effluent. The aqueous phase effluent
may
then be processed to chemically remove ions that might interfere with
commercial
bitumen extraction when part of the aqueous phase ends up as recycle water.
The
agglomerated bitumen phase may then be discarded or processed to recover
valuable
bitumen while keeping the gel forming components in a form that does not allow
these to disperse in tailings ponds that may produce recycle water for
commercially
processing of oil sands.
While the present disclosure has concentrated on the use of a truncated
conical
vessel with central mixture inlet and apertured cylindrical wall outlet, the
present
invention also contemplates the use of a more conventional bitumen
agglomerator of
the prior art of the inventor that is shaped in the form of cylindrical vessel
with a
central inlet and with an apertured cylindrical vessel wall that forms the
agglomerated
mixture outlet. Such a more conventional bitumen agglmerator may be used
instead,
but with lower efficiency, to capture ultrafine and bi-wetted particulates
into the
bitumen phase of sludge.
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. Numerous modifications and alternative arrangements may
be
devised by those skilled in the art without departing from the spirit and
scope of the
present invention, and the appended claims are intended to cover such
modifications
and arrangements. Thus while the present 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, including, but not
limited to,
variations in size, materials, shape, form, function and manner of operation,
assembly
and use may be made without departing from the principles and concepts set
forth
herein.
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