Note: Descriptions are shown in the official language in which they were submitted.
DOCKET NO.: NS-641
DEPOSITION OF FLOCCULATED TAILINGS
Technical Field
[0001] The following relates to a process for dewatering tailings such
as oil sands
tailings. In particular, a process is provided for optimizing the dewatering
of polymeric
flocculant-treated tailings by controlling the deposition or discharge
conditions of polymeric
flocculant-treated tailings into a deposition area.
Background
[0002] Oil sands deposits such as those found in the Athabasca Region
of Alberta,
Canada, generally comprise water-wet sand grains held together by a matrix of
viscous heavy
oil or bitumen. Bitumen is a complex and viscous mixture of large or heavy
hydrocarbon
molecules that contain a significant amount of sulfur, nitrogen and oxygen.
Oil sands
processing involves extraction and froth treatment to produce diluted bitumen
that is further
processed to produce synthetic crude oil and other valuable commodities. The
extraction of
bitumen from sand using hot water processes yields large volumes of fine
tailings composed
of fine silts, clays, residual bitumen and water. Mineral fractions with a
particle diameter less
than 44 microns are referred to as "fines." These fines are typically clay
mineral suspensions,
predominantly kaolinite and illite. The fine tailings suspension is typically
between 55 and
85% water and/or 15 to 45% fine particles by mass. Dewatering of fine tailings
occurs very
slowly.
[0003] Generally, the fine tailings are discharged into a storage pond
for settling and
dewatering. When first discharged in the pond, the very low density material
is referred to as
thin fine tailings. Dewatering of thin fine tailings occurs very slowly. After
a few years, when
the thin fine tailings have reached a solids content of about 30-35 wt%, they
are referred to as
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fluid fine tailings (FFT) and sometimes mature fine tailings (MFT), which
still behave as a
fluid-like colloidal suspension. The fact that mature fine tailings behave as
a fluid and have
very slow consolidation rates significantly limits options to reclaim tailings
ponds. Thus, a
challenge facing the industry remains the removal of water from the fluid fine
tailings to
strengthen the deposits, so that they can be reclaimed and no longer require
containment.
[0004] Most of the recent efforts surrounding the elimination of
tailings ponds
involve removing FFT from the ponds, such as by dredging, and performing one
or more of
mechanical, chemical or electrical processes followed by placement of the
partially dewatered
tailings to form a landform. One such process involves flocculating FFT using
conventional
flocculating agents. The flocculated solids are then added to a tailings
deposition site where
accelerated dewatering can occur. The current state of the art attempts to
achieve optimum
flocculant dosage and optimum mixing in a mixing vessel or in-line mixer
located at some
distance along a discharge pipe (see, for example, CA 2,789,678 and CA
2,678,818).
However, achieving optimum flocculation has been a challenge for the industry
and the
majority of recent development in the industry has been focused on the
optimization of
polymer/FFT and not much attention has be placed on the manner in which FFT is
deposited.
[0005] It was recently discovered by the present applicant that the
manner in which
flocculated tailings are deposited in deposition sites can have a negative
impact on the
dewatering of the deposit, in particular, when dealing with fully (completely)
flocculated
tailings. Up until now, it was commonly believed that additional mixing was
required at
discharge, as obtaining fully (completely) flocculated tailings was not
possible. Thus, the
previous state of the art relied on the discharge velocity at deposition to
improve
tailings/flocculant mixing to improve flocculation of the tailings (see, for
example, Canadian
Patent Application No. 2,886,983).
[0006] Hence, there is a need in the industry to be able to achieve
fully (completely)
flocculated tailings, together with a deposition scheme for depositing same,
to enhance the
dewatering of flocculated tailings.
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Summary
[0007] The present application is directed to a method of dewatering
tailings, in
particular, oil sands tailings, by first optimizing flocculation conditions to
obtain fully
(completely) flocculated tailings and then controlling the discharge of the
flocculated tailings
into a tailings deposition site. Thus, broadly stated, in one aspect, a
process for dewatering
tailings is provided, comprising:
= providing a tailings feed having a solids content in the range of about
10 wt% to about
70 wtc/0;
= adding an effective amount of a polymeric flocculant to the tailings feed
and mixing the
polymeric flocculant and tailings feed mixture in a mixing device sufficient
to flocculate
the tailings and minimize the capillary suction time (CST) of the flocculated
tailings to
form fully flocculated tailings;
= transporting the fully flocculated tailings to a deposition area;
= discharging the fully flocculated tailings into the deposition area at a
discharge velocity
of substantially zero to minimize further mixing;
= naturally forming a sloped beached material deposit in the deposition
area whereby
water is released from the sloped beached material to form a released water
pool that
pools away from the sloped beached material; and
= continuously removing water from the released water pool to ensure that
the sloped
beached material at a discharge point is at a higher elevation than the
released water
pool to minimize any buoyant forces on the beached material deposit.
[0008] In one embodiment, the mixing device is a dynamic mixer. In one
embodiment, the tailings are oil sand tailings. In one embodiment, the oil
sand tailings are
fluid fine tailings (FFT) or mature fine tailings (MFT). In one embodiment,
the tailings have a
solids content in the range of about about 15 wt% to about 45 wt%, in
particular, when the
tailings are FFT or MFT. In one embodiment, the FFT or MFT are diluted to
about 20 wt% to
about 30 wt% solids content.
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[0009] In one embodiment, the polymeric flocculant is a water-soluble
polymer
having a moderate to high molecular and an intrinsic viscosity of at least
about 3 dl/g
(measured in 1M NaCI at 25 C). The polymeric flocculant may be cationic, non-
ionic,
amphoteric, or anionic. The polymeric flocculant can be in an aqueous solution
at a
concentration of about between 0.05 and 5% by weight of polymeric flocculant.
Typically, the
polymeric flocculant solution will be used at a concentration of about 1 g/L
to about 5 g/L.
[00010] Suitable doses of polymeric flocculant can range from 10 grams
to 10,000
grams per tonne of tailings. Preferred doses range from about 400 to about
1,500 grams per
tonne of tailings.
[00011] In one embodiment, the tailings feed is first treated with a
coagulant prior to
the addition of the polymeric flocculant to form fully flocculated tailings.
In one embodiment,
the coagulant is gypsum added at an average dosage of about 900 to about 1500
grams per
tonne. In one embodiment, the coagulant is flue-gas desulfurization (FGD)
solids added at an
average dosage of about 1000 to about 4000 grams per tonne. Flue-gas
desulfurization
(FGD) is a set of technologies used to remove sulfur dioxide (S02) from
exhaust flue gases of
fossil-fuel power plants. Particularly useful are FGD solids produced when
using calcium
oxide to remove sulfur dioxide from flue gases and emissions, which, on
average, are
comprised of about 30% slaked lime, 6% gypsum and 64% inerts. In one
embodiment, the
coagulant is lime added at an average dosage of about 900 to about 1500 grams
per tonne.
In one embodiment, the coagulant is alum added at an average dosage of about
900 to about
1500 grams per tonne.
[00012] In one embodiment, the fully flocculated tailings has a
capillary suction time
(CST) of <75 seconds, preferably < 50 seconds, and more preferably < 25
seconds. In one
embodiment, the fully flocculated tailings are discharged either sub-aerially
or sub-aqueously.
In one embodiment, the fully flocculated tailings are deposited sub-aerially
at or near the
surface of the tailings deposit. In one embodiment, the fully flocculated
tailings are
transported to the deposition area by means of a horizontal pipe, said
horizontal pipe having a
discharge end comprising an elbow and a vertical pipe of sufficient length to
eliminate the
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horizontal velocity of the fully flocculated tailings such that the velocity
of the fully flocculated
tailings upon discharge is substantially zero.
[00013] Additional aspects and advantages of the present method will be
apparent in
view of the description, which follows. It should be understood, however, that
the detailed
description and the specific examples, while indicating preferred embodiments,
are given by
way of illustration only, since various changes and modifications will become
apparent to
those skilled in the art from this detailed description.
Brief Description of the Drawincis
(00014) The method provided will now be described by way of an exemplary
embodiment with reference to the accompanying simplified, diagrammatic, not-to-
scale
drawings:
[00015] FIG. 1 shows a schematic of a method for treating and dewatering
raw Fluid
Fine Tailings (FFT).
[00016] FIG. 2 is a photograph of a deposition cell useful in practicing
the method
provided herein.
[00017] FIG. 3 is a photograph of a discharge pipe in a deposition cell
modified to
ensure almost zero velocity at discharge.
[00018] FIG. 4 is a photograph showing a close up of the discharge end
of the
discharge pipe of FIG. 3.
[00019] FIG. 5 is a photograph of a deposition cell filled with fully
flocculated tailings,
which illustrates the dewatering of the fully flocculated tailings.
[00020] FIG. 6 is a frequency distribution graph whereby the x-axis
shows the CST
value range and the y-axis is the number of occurrences of that CST value
during the course
of the test program.
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Detailed Description
[00021] A method is provided for dewatering tailings. As used herein,
the term
"tailings" means any tailings produced during a mining operation, including
tailings derived
from oil sands extraction operations, which contain a fines fraction. The term
is meant to
include fluid fine tailings (FFT) from tailings ponds (also referred to as
mature fine tailings
(MFT)) and other fine tailings (for example, thickener underf low or froth
treatment tailings,
which may bypass a tailings pond) which are derived from ongoing oil sands
extraction
operations. As used herein, the term "fine tailings" means tailings that are
derived from oil
sands extraction operations that contain a fines fraction. Fines are generally
defined as solids
having a diameter less than 44 microns. The raw FFT will generally have a
solids content of
around 30 to 40 wt% and may be diluted to about 20-30 wt% with water for use
in the present
process. However, any oil sands fine tailings having a solids content ranging
from about 10
wt% to about 70 wt% or higher can be used.
[00022] As used herein, the term "flocculant" refers to a reagent that
bridges the
neutralized or coagulated particles into larger agglomerates, resulting in
more efficient
settling. Flocculants useful herein are generally anionic, nonionic, cationic
or amphoteric
polymers, which may be naturally occurring or synthetic, having relatively
high molecular
weights. Preferably, the polymeric flocculants are characterized by molecular
weights ranging
between about 1,000 kD to about 50,000 kD. Suitable natural polymeric
flocculants may be
polysaccharides such as dextran, starch or guar gum. Suitable synthetic
polymeric
flocculants include, but are not limited to, charged or uncharged polyacrylam
ides, for
example, a high molecular weight polyacrylamide-sodium polyacrylate co-
polymer. Useful
flocculating polymers or "flocculants" include charged or uncharged
polyacrylamides such as
a high molecular weight polyacrylamide-sodium polyacrylate co-polymer with
about 25-35%
anionicity. The polyacrylamide-sodium polyacrylate co-polymers may be branched
or linear
and have molecular weights that can exceed 20 million.
[00023] Other useful polymeric flocculants can be made by the
polymerization of
(meth)acrylamide, N-vinyl pyrrolidone, N-vinyl formamide, N,N
dimethylacrylamide, N-vinyl
acetamide, N-vinylpyridine, N-vinylimidazole, isopropyl acrylamide and
polyethylene glycol
methacrylate, and one or more anionic monomer(s) such as acrylic acid,
methacrylic acid, 2-
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acrylamido-2-methylpropane sulphonic acid (ATBS) and salts thereof, or one or
more cationic
monomer(s) such as dimethylaminoethyl acrylate (ADAM E), dimethylaminoethyl
methacrylate
(MADAME), dimethydiallylammonium chloride (DADMAC), acrylamido propyltrimethyl
ammonium chloride (APTAC) and/or methacrylamido propyltrimethyl ammonium
chloride
(MAPTAC).
[00024] As used herein, the term "coagulant" refers to a reagent that
neutralizes
repulsive electrical charges surrounding particles to destabilize suspended
solids and to
cause the solids to agglomerate. Suitable coagulants include, but are not
limited to, alum,
aluminum chlorohydrate, aluminum sulphate, lime (calcium oxide), slaked lime
(calcium
hydroxide), calcium chloride, magnesium chloride, iron (II) sulphate (ferrous
sulphate), iron
(Ill) chloride (ferric chloride), sodium aluminate, gypsum (calcium sulphate
dehydrate), Flue
Gas Desulfurization Solids ("FGD solids", the composition of which is
described in more detail
below), or any combination thereof.
[00025] As used herein, "g/tonne" or "g/t" means an amount of coagulant,
FGD
solids or flocculant (in grams) added per tonne of tailings solids.
[00026] As used herein, "flocs" are larger-size clusters of mineral
particles produced
as a result of flocculation. "Flocculation" is a process of contact and
adhesion of mineral
particles due to the addition of a flocculant, a coagulant or a combination of
a flocculant and
coagulant.
[00027] As used herein, "fully flocculated tailings" means tailings
(either untreated
tailings or tailings that have been first treated with a coagulant such as
gypsum, alum, lime or
FGD solids) that are treated with a flocculant, resulting in a flocculant-
treated tailings product
having a low capillary suction time (CST). CST can be measured using a Triton
Electronics
Ltd. Capillary Suction Time tester and measures how long it takes for water to
be suctioned
through a filter. Low values indicate rapid dewatering, which is the case when
tailings are
fully flocculated, whereas high values indicate slow dewatering ability and,
thus, poor
flocculation. Thus, fully flocculated tailings would have a low CST and poorly
flocculated
tailings would have a high CST. For tailings such as FFT or MFT having about
25 wt% to
about 30 wt% solids, a low CST would be < 50 seconds, preferably <25 seconds.
For
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tailings such as FFT or MFT having a higher solids content, i.e., about 30 wt%
to about 35
wt% solids, a low CST would be about <50 seconds to about <75 seconds.
Further, "fully
flocculated tailings" are characterized by the water release when the fully
flocculated tailings
are slowly poured over the edge of a sample bucket in that the fully
flocculated tailings will
break off in chunks with clear water released as the chunks break away. "Fully
flocculated
tailings" can also be determined by visually inspecting the flocculated
tailings in either a glass
pipe or a glass jar where a flocculated structure having large water channels
between the
flocs is observed. In operational practice, a flocculated tailings sample is
typically both
visually inspected and the CST is determined in the lab.
[00028] FIG. 1 shows a simplified flow sheet for producing fully
flocculated tailings.
In particular, raw fluid fine tailings (Raw FFT) 10, taken from the FFT
centrifuge plant main
feedline, was diluted with recycle water 12 for density control. Recycle water
was supplied
from the FFT centrifuge plant. The FFT was pretreated with FGD solids slurry
14, which slurry
was formed by mixing FGD solids 16 and recycle water 12 in mix tank 18. The
FGD solids
slurry 14 was added to the Raw FFT 10 upstream of a static mixer 20 and the
Raw FFT and
FGD solids mixture 22 was then fed to a residence time tank 24, which tank was
equipped
with mixers, to provide sufficient time for the calcium ions present in the
FGD solids slurry to
dissolve into solution and interact with the clay particles present in the
FFT. The pretreated
FFT 26 was then fed to a hydrofoil dynamic mixer 28 where polymer solution 30
was added to
create a flocculated FFT stream 32 that was subsequently sent to a deposition
cell. It is
understood, however, that any dynamic mixer could be used.
[00029] A dynamic mixer is used to continuously mix the oil sands fluid
fine tailings
with the water-soluble flocculating polymer, which results in a more
consistent production of
well-defined floc structures and subsequently leads to good dewatering. Some
advantages of
using a hydrofoil dynamic mixer include the ability to control the mixing
energy input
independent of the feed flow rate; it is a more reliable operation; and it
results in more robust
flocculation performance (i.e., more robust flocs). The ability to control the
energy input
allows one to obtain the optimal operation regime for floc formation, as above
or below the
optimal operation regime could result in over-shearing or under-mixing of the
mixture of FFT
and flocculant solution, both of which result in poor water release. Further,
use of a stirred
tank reactor allows the operator to control the mixing time (i.e., residence
time) of the
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flocculant to more readily ensure a more robust flocculation performance
without over-
shearing or under-mixing. Ultimately, however, any mixing device can be used
as long as the
mixing is sufficient to flocculate the tailings and minimize the capillary
suction time (CST) of
the flocculated tailings, resulting in fully flocculated tailings.
[00030] An aerial view of a deposition cell that can be used for
depositing fully
flocculated tailings is shown in FIG. 2. The deposition cell shown in FIG. 2
was used in
Example 1 below to show how deposition of fully flocculated tailings should be
at or near a
zero discharge velocity for optimum dewatering. In particular, FIG. 3 shows a
horizontal
discharge pipe that transports the fully flocculated tailings from the dynamic
mixer to the
deposition cell. It was discovered by the present applicant that deposition of
fully flocculated
tailings from a horizontal pipe resulted in excess mixing energy applied to
the fully flocculated
tailings, resulting in over-shearing of the flocs and poor water release. This
is believed to be
due to the horizontal velocity of the tailings travelling through the
transport pipe. Hence, a
typical horizontal deposition pipe of the prior art, which generally has a
large diameter of
about 20 to 24 inches, was modified such that the discharge velocity of the
tailings upon
placement in the deposition cell was at or near zero, i.e., so that there is
no further mixing and
placement or deposition of the fully flocculated tailings is essentially
quiescent. This was
accomplished by adding a 90-degree elbow to the end of the horizontal pipe,
which reduced
the horizontal velocity to essentially zero. In addition, the vertical portion
of the 90-degree
elbow, measured from the bottom of the elbow, is relatively short, e.g., less
than about two
pipe diameters in length resulting in a relatively short vertical discharge
end of the deposition
pipe. Thus, the addition of a 90-degree elbow, together with the large
discharge pipe
diameter, was sufficient to essentially eliminate the horizontal velocity of
the tailings as well as
minimize the vertical velocity of the tailings upon discharge, resulting in
minimum further
mixing of the tailings at discharge. .
[00031] As can be seen in FIG. 3, the discharge end of the discharge
pipe of the
present application is close to the surface of the deposition cell. Thus, the
tailings essentially
"fountain" up near or slightly beneath the surface of the tailings deposit. In
one embodiment,
the discharge end is between about 20 inches to about 40 inches off the
ground. Essentially,
the height of the vertical pipe is selected to ensure no further mixing of the
fully flocculated
tailings occurs, i.e., is of sufficient length to eliminate the horizontal
velocity; thus, the tailings
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are deposited at essentially zero velocity at the surface of the tailings
deposition (i.e., velocity
of the tailings is net zero at discharge).
[00032] FIG. 4 is a close-up photograph of the end of pipe of FIG. 3.
In FIG. 4, the
fully flocculated tailings will be deposited sub-aerially, although it is
understood that the
tailings could also be deposited sub-aqueously, as long as the end of pipe is
designed such
that the discharge velocity is substantially zero at the surface of the
tailings deposit. By
depositing the fully flocculated tailings with essentially zero velocity,
i.e., with only a minimal
vertical velocity and no horizontal velocity, the stacking of the tailings
deposit is maximized,
thereby maximizing the slope of the tailings deposit and facilitating the
release and removal of
the water.
[00033] When tailings are deposited sub-aqueously, the water or
tailings will help
minimize the vertical velocity, which would be beneficial as long as the
deposit can
accumulate above the water line. This will only occur to a small extent unless
the water
released from the flocculation process is continuously removed. When released
water is
continuously removed, the end of the deposition pipe as described above will
be submerged
in the beached material, however, additional tailings that are deposited will
form a naturally
occurring channel so that the tailings would flow up though this channel and
be deposited at
essentially zero velocity.
[00034] FIG. 5 is an aerial photograph of a tailings deposition cell
showing the water
that is released from the stacked, fully flocculated tailings deposit (also
referred to herein as
"beached material"). As can be seen in FIG. 5 deposition of the fully
flocculated tailings
results in a naturally formed slope of beached material where the water
released from the
tailings forms a released water pool, which is at a lower elevation than the
stacked beached
material. It is important that the release water be continuously removed to
ensure the
beached material is not submerged in the released water so as to minimize any
buoyant
forces on the deposited or beached material. In addition, it is desirable to
have the beached
material exposed to the atmosphere so that the beached material can be further
dewatered/consolidated for reclamation. The water was pumped off utilizing a
diesel driven
pump, although it is understood that other means for removing the released
water pool could
be used. Thus, the entire bottom of the deposition cell was sloped towards the
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structure where its base was about 1 meter lower in elevation than the
discharge point.
Sloping the cell facilitates better drainage of the deposited material. The
purpose of the
decant structure is to allow for longer-term drainage of the cell surface once
the deposit
reaches its final fill height. Underdrainage as is known in the art can also
be incorporated into
the cell.
Example 1
[00035] A deposition cell, such as shown in FIG. 2, was used in the
present
experiment. Fluid fine tailings (FFT) was sourced from a tailings pond and the
typical solids
content, i.e., mineral solids + bitumen, of the raw FFT feed averaged around
33.5 wt%. The
raw FFT was diluted with recycle water and the diluted FFT stream had an
average total
solids content of about 30.5 wt%. During the course of the experiment, which
lasted about 20
days, close to 131,000m3 of diluted FFT was flocculated and sent to the
deposition cell having
a volume of about 70,000 m3. In the present experiment, the diluted FFT was
first treated
with FGD solids using an FGD solids slurry of about 13.5 wt% solids. The
average dosage of
FGD solids was about 3950 g/tonne. The FGD solids was added to the diluted FFT
stream
and mixed utilizing an inline static mixer before the mixture was sent to an
agitated residence
time tank. A hold up time of approximately 10 minutes was achieved in the
tank, which was
adequate for dissolution of the calcium ions in the FGD solids to cause
coagulation of the clay
particles present in the FFT. Atypical FGD solids chemical composition is
shown in Table 1.
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[00036] Table 1. Chemical Composition of FGD Solids
Chemical Average
Name Common Name
Formula wt.%
CaS03-1/2H20 Calcium sulfite 44 8
hemihydrate
CaSO4-2H20 Calcium sulfate Gypsum 6 1
dihydrate
CaCO3 Calcium carbonate Limestone (calcite) 9 3
CaO Calcium oxide Quicklime <1
Ca(OH)2 Calcium hydroxide Slaked lime/hydrated lime 30 5
lnerts Coke 10 2
H20 Water 1 0.5
[00037] The FGD solids treated FFT was then transferred to a hydrofoil
dynamic
mixer consisting of two 30 inch diameter hydrofoil impellers driven by a 400
hp electric motor.
Polymer was also added to the hydrofoil dynamic mixer using a polymer
injection quill
fabricated from 4-inch schedule 160 steel pipe and was positioned to deliver
the polymer
solution near the impeller tips along the vessel centerline. The polymer used
was a
polyacrylamide with a medium charge density and high molecular weight with an
overall
average dosage of 1175 g/tonne. The quality of the flocculated product was
monitored via
capillary suction time (CST) measurements in order to ensure that the FFT was
fully
flocculated, i.e., to ensure proper dewatering performance was adhered to at
all times.
Polymer dosage was adjusted based on CST measurements to keep the CST values
in the
range of 10-20 seconds. CST measurements were taken on an hourly basis and
could be
taken at the exit of the hydrofoil dynamic mixer or at the end of pipe
location. CST
measurements of the fully flocculated tailings (FFT) were measured with a
Triton Electronics
Type 319 Multi-CST, 5-channel unit. The measurement heads were equipped with
1.8 cm
diameter by 2.5 cm high funnels. Whatman TM Grade 4 (55 mm diameter) filter
paper was
used for the CST measurements. All of the CST data that was taken during the
filling of the
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deposition cell (both after the hydrofoil dynamic mixer and the end of pipe)
is plotted in a
frequency distribution graph shown in FIG. 6, where the x axis shows the CST
value range
and the y axis is the number of occurrences of that CST value during the
course of the test
program. It can be seen from FIG. 6 that the average CST value is in the 10-15
second range
with over 95% of all the values being below a value of 30 seconds. Adequate
dewatering was
deemed to have been achieved if any flocculated FFT sample has a CST value of
less than
50 seconds. Based on this criterion, all of the flocculated FFT that was
deposited in the cell
met the specification of being properly flocculated.
[00038] Nearly 80,000 m3 of release water was removed from the cell, as
water was
continuously released while the flocculated material was deposited. After
about a month or
two, the total solids content of the dewatered material was about 52-55 wt%.
It is understood
that the dewatered material will continue to dewater over time.
Interpretation
[00039] The corresponding structures, materials, acts, and equivalents
of all means
or steps plus function elements in the claims appended to this specification
are intended to
include any structure, material, or act for performing the function in
combination with other
claimed elements as specifically claimed.
[00040] References in the specification to "one embodiment", "an
embodiment", etc.,
indicate that the embodiment described may include a particular aspect,
feature, structure, or
characteristic, but not every embodiment necessarily includes that aspect,
feature, structure,
or characteristic. Moreover, such phrases may, but do not necessarily, refer
to the same
embodiment referred to in other portions of the specification. Further, when a
particular
aspect, feature, structure, or characteristic is described in connection with
an embodiment, it
is within the knowledge of one skilled in the art to affect or connect such
module, aspect,
feature, structure, or characteristic with other embodiments, whether or not
explicitly
described. In other words, any module, element or feature may be combined with
any other
element or feature in different embodiments, unless there is an obvious or
inherent
incompatibility, or it is specifically excluded.
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[00041] It is further noted that the claims may be drafted to exclude
any optional
element. As such, this statement is intended to serve as antecedent basis for
the use of
exclusive terminology, such as "solely," "only," and the like, in connection
with the recitation of
claim elements or use of a "negative" limitation. The terms "preferably,"
"preferred," "prefer,"
"optionally," "may," and similar terms are used to indicate that an item,
condition or step being
referred to is an optional (not required) feature.
[00042] The singular forms "a," "an," and "the" include the plural
reference unless the
context clearly dictates otherwise. The term "and/or" means any one of the
items, any
combination of the items, or all of the items with which this term is
associated. The phrase
"one or more" is readily understood by one of skill in the art, particularly
when read in context
of its usage.
[00043] The term "about" can refer to a variation of 5%, 10%,
20%, or 25% of
the value specified. For example, "about 50" percent can in some embodiments
carry a
variation from 45 to 55 percent. For integer ranges, the term "about" can
include one or two
integers greater than and/or less than a recited integer at each end of the
range. Unless
indicated otherwise herein, the term "about" is intended to include values and
ranges
proximate to the recited range that are equivalent in terms of the
functionality of the
composition, or the embodiment.
[00044] As will be understood by one skilled in the art, for any and
all purposes,
particularly in terms of providing a written description, all ranges recited
herein also
encompass any and all possible sub-ranges and combinations of sub-ranges
thereof, as well
as the individual values making up the range, particularly integer values. A
recited range
includes each specific value, integer, decimal, or identity within the range.
Any listed range
can be easily recognized as sufficiently describing and enabling the same
range being broken
down into at least equal halves, thirds, quarters, fifths, or tenths. As a non-
limiting example,
each range discussed herein can be readily broken down into a lower third,
middle third and
upper third, etc.
[00045] As will also be understood by one skilled in the art, all
language such as "up
to", "at least", "greater than", "less than", "more than", "or more", and the
like, include the
number recited and such terms refer to ranges that can be subsequently broken
down into
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sub-ranges as discussed above. In the same manner, all ratios recited herein
also include all
sub-ratios falling within the broader ratio.
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