Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
Binder and method of forming the binder for granulation,
aggregation and structuring of mineral solids
TECHNICAL FIELD
[0001] The present invention relates to composition and method for
granulation, aggregation and structuring of mineral solids.
BACKGROUND
[0002] Mining processes world-wide produce waste streams of solids-
containing water slurries. Generally these water slurries are sent to ponds
where, within months to a few years, the solids settle to a reclaimable
condition and the supernatant water is returned to process.
[0003] The mining and processing of oil sands is a major industry in
the province of Alberta, Canada. As in virtually all mining processes, mine
waste disposal is a major cost and a major environmental concern.
[0004] From the inception of Alberta oil sands processing by hot water
extraction, a fine particle slurry containing predominantly clays has been
produced. Unfortunately the usual tailings pond gravity separation process
has not been effective in settling the fine clays from the water. Instead, the
fine clay solids have concentrated and remained in stable suspensions of up
to 40% clay solids, and these suspensions are projected to be stable for
hundreds of years. It is a government requirement that these clay solids be
separated and recovered to be used in restoration of the mine site. Clay
slurries that have not been sent to tailings ponds are referred to as fresh
fine
tailings (FFT). Ponded clay slurries are referred to as mature fine tailings
(M Fr).
[0005] Industry efforts over the last decades have focused on
essentially two routes to fine tailings reclamation. The first route involves
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blending the clay tailings slurry, usually MFT, with sand separated from oil
sands ore during bitumen extraction. Weight ratios in these sand-to-clay
blends are described as Sand:Fines ratios (SFR's). One particular process,
referred to as Combined Tailings (CT), could have SFR's of from 4:1 to 6:1,
which results in immense quantities of sand compared to the fines being
sequestered. In order to assist dewatering of these sand-to-fines blends
gypsum or alum are often added. Unfortunately, these inorganic salts add
undesirable dissolved-solids loading to the process water and these sulfur-
containing salts may eventually produce dangerous gases on the mine site.
[0006] The obvious drawback of the CT process is that huge quantities
of sand are required to sequester disproportionately small amounts of clay.
Handling and controlled-metering of these volumes of clay and sand is both
a difficult and expensive in process. Large volumes of sand are required for
mine-site construction including building dykes to contain ever increasing
volumes of MFT. Because of these uses, sand has become a scarce
commodity.
[0007] A second route to dewatering MFT has been to treat the MFT
with flocculants and other chemical additives to accelerate the solids
settling
process, using reduced amounts of sand. This treated MFT is pumped to
what are essentially small tailings ponds called Dedicated Deposition Areas
(DDAs).
[0008] A desired result is that the clay solids in the DDA will, within
an
acceptable time-frame, settle and consolidate to facilitate incorporation of
the settled fines in mine-site reclamation. However, regardless of any
significant reduction of settling times in the DDA, the fines will still be
fines.
Any mine site reclamation process seeks to prevent re-release of
unconsolidated fines back to process water or the environment.
[0009] Additionally, the water slurries of fine clays may also contain
residual bitumen from the hot water bitumen extraction process. Residual
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bitumen, as well as other chemicals added in or following the extraction
process inhibit the effective separation and disposal of clay from the water
slurry. It is highly desirable that residual bitumen be trapped in the solids.
[0010] The present disclosure relates to the treatment and disposal of
oil sands fine clay tailings from (e.g. Alberta) oil sands bitumen production
as part of mine-site reclamation.
[0011] To address the deficiencies in current practices in oil sands
operations, there is a need to provide a binder composition, use of the
binder composition, and to provide a granulation process for fine clay
particles that does not require the incorporation of sand and/or is broadly
applicable and therefore not limited to the different types of water swelling
clays.
SUMMARY OF THE INVENTION:
[0012] It is an embodiment of the present invention to provide a
method to produce a binder that granulates, aggregates and structures fine
clay particles. According to an embodiment, granulation is produced in a
fine clay tailings slurry by the sequential addition of two water soluble
organic polymers that react to form in situ a granulated binder. In one
aspect, the disclosed binder granulates the fine tailings particles and the
granulated tailings particles aggregate to form a structure that can be
stacked, centrifuged, or sub-aqueously deposited without re-release of fines
to process or to the environment.
[0013] According to an embodiment, there is provided a method of
producing in-situ (i.e. on-site and in the presence of fines) a granulating
binder in an aqueous dispersed mineral slurry, the process comprising:
[0014] (a) providing an aqueous slurry comprising slurrying water
and solid mineral component(s), and
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[0015] (b) adding to the dispersed slurry of (a) sufficient quantities
of
an anionic flocculant, and
[0016] (c) adding to the dispersed slurry of (b) sufficient quantities
of
a cationic coagulant, to
[0017] (d) cause the two components in (b) and (c) to react to form a
granulating binder that granulates and aggregates the mineral components
of the aqueous slurry.
[0018] According to an embodiment, there is provided a method for
treating tailings derived from oil sands extractions to form a granulated
aggregated material and an aqueous component.
[0019] According to an embodiment, there is provided use of a
composition for treating fine tailings derived from oil sands extractions
comprising a slurry comprising water, solid mineral component(s), and/or
organic components to form aggregated material and an aqueous
component, the composition comprising: an anionic polymer flocculant and a
cationic polymer coagulant, wherein when the composition is reacted in situ
with tailings, will convert the tailings into a granulated aggregated material
and an aqueous component.
[0020] According to an embodiment, there is provided a method for
treating fine tailings of a slurry comprising water, solid mineral
component(s), and/or organic components derived from oil sands extractions
to form a granulated aggregated material and an aqueous component, the
method comprising:
subjecting tailings to a sufficient dosage of an anionic polymer flocculant
and to a sufficient dosage of a cationic polymer coagulant so as to
convert the tailings into a granulated aggregated material and an
aqueous component.
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[0021] In one aspect, the subjecting the tailings comprises subjecting
the tailings to the sufficient dosage of the anionic polymer flocculant to
form
a paste material; and then subjecting the paste material to the sufficient
dosage of the cationic polymer coagulant, wherein the reaction of the anionic
polymer flocculant with the cationic polymer coagulant forms a granulating
binder that converts the paste material into the granulated aggregated
material and the aqueous component.
[0022] The method further comprising one or more of mixing the paste
material before the subjecting the paste material to the cationic polymer
coagulant and mixing after the subjecting the paste material to the cationic
polymer coagulant.
[0023] In one aspect, the sufficient dosage of the anionic polymer
flocculant is greater than about 250 g/ton of tailing solids; is greater than
about 450 g/ton of tailing solids; is greater than about 1000 g/ton of tailing
solids; or is about 1,115 g/ton of tailing solids.
[0024] In one aspect, the sufficient dosage of the cationic polymer
coagulant (active) is greater than about 25 g/ton of tailing solids; is
greater
than about 100 g/ton of tailing solids; or is about 995 g/ton of tailing
solids.
[0025] In one aspect, the sufficient dosage of the anionic polymer
flocculant is at least about 1.5 to about 2 times the dosage of conventional
flocculation and the sufficient dosage of the cationic coagulant at least
about
18 to about 40 times the active dosage of conventional coagulation.
[0026] In one aspect, the anionic polymer is a copolymer or terpolymer
anionic flocculant, or is a high-molecular-weight copolymer or terpolymer
anionic flocculant.
[0027] In one aspect, the anionic polymer flocculant is a sodium
acrylate/acrylamide copolymer, a potassium acrylate/acrylamide copolymer,
Date Recue/Date Received 2020-09-11
ammonium acrylate/acrylamide copolymer, or a calcium
diacrylate/acrylamide copolymer.
[0028] In one aspect, the sodium acrylate/acrylamide copolymer is a
35 wt.% or a 46 wt.% sodium acrylate/acrylamide copolymer.
[0029] In one aspect, the sodium acrylate/acrylamide copolymer is a
high molecular weight copolymer.
[0030] In one aspect, the calcium diacrylate/acrylamide copolymer is a
40 wt.% calcium diacrylate/acrylamide copolymer.
[0031] In one aspect, the calcium diacrylate/acrylamide copolymer is a
medium or a high molecular weight copolymer.
[0032] In one aspect, the cationic polymer coagulant is a high
molecular weight diallyl dimethyl ammonium chloride polymer (DADMAC) or
a high molecular weight dimethylamine/epichlorohydrin copolymer
(DMA/EPI).
[0033] In one aspect, the method further comprising admixing a dry
cationic flocculant with the liquid cationic polymer coagulant before the step
of subjecting the tailings to the sufficient dosage of the cationic polymer
coagulant. In one aspect, the admixing produces a blend of cationic polymer
flocculant and high molecular weight dimethylamine/epichlorohydrin
copolymer (DMA/EPI).
[0034] In one aspect, the blend comprises up to 20 wt.% cationic
polymer flocculant; comprises less than or about 10 wt.% cationic polymer
flocculant; or is 5 wt.% cationic polymer flocculant and 95 wt.% DMA/EPI
(actives) blend.
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[0035] In one aspect, the method further comprising the step of
diluting the cationic polymer coagulant with water before the step of
admixing of the cationic polymer flocculant.
[0036] In one aspect, the cationic polymer flocculant is a
quaternary/acrylamide cationic dry flocculant.
[0037] In one aspect, the further comprising diluting the anionic
polymer flocculant solution with water before the step of subjecting the
tailings to the sufficient dosage of the anionic polymer flocculant.
[0038] In one aspect, the method further comprising separating the
granulated aggregated material from the aqueous component.
[0039] In one aspect, the aqueous component comprises water.
[0040] In one aspect, the tailings are FFT or MFT.
[0041] In one aspect, the tailings are extraction tailings which are
tailings which are obtained after a first extraction process.
[0042] In one aspect, the granulated aggregated material comprises
sequestered contaminants. In one aspect, the sequestered contaminants
are one or more of metalloids, polyatomic non-metals, and surfactants. In
one aspect, the sequestered contaminants comprise arsenic, selenium, and
naphthenate.
[0043] In one aspect, the tailings are particulates that are less than
or
equal to 44 microns.
[0044] According to an embodiment, there is provided a granulating
binder for immobilizing mineral solids within a waste stream of mineral
solids-containing water slurry obtained from a mining process, the
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granulating binder comprises a sufficient dosage of an anionic flocculant with
a sufficient dosage of a cationic coagulant, wherein the reaction of the
anionic flocculant with the cationic coagulant in the presence of mineral
solids within a waste stream of mineral solids-containing water slurry forms
the granulated binder that will immobilize the mineral solids into a
granulated aggregated material.
[0045] In one aspect, the sufficient dosage of the anionic polymer
flocculant is mixed with the mineral solids to form a paste material; and the
sufficient dosage of the cationic polymer coagulant is mixed with the paste
material to convert the paste material into the granulated aggregated
material.
BRIEF DESCRIPTION OF THE DRAWINGS
[0046] Figure 1 is a photo showing the formation of the white haze
after initial admixing anionic polymer flocculant and a cationic polymer
coagulant, using a method in accordance with an embodiment of the
invention;
[0047] Figure 2 is a photo showing the formation of a coalesced form
of an insoluble white cocoon (binder) upon continued stirring of the white
haze of figure 1;
[0048] Figure 3 is a photo showing the wet aggregated structure
obtained by using a method in accordance with an embodiment of the
invention;
[0049] Figure 4 is a photo of a deposit from Figure 3 obtained by using
a method in accordance with an embodiment of the invention after drying
and re-submerged in water;
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[0050] Figure 5 is a photo of a larger volume of the stackable
aggregate obtained by using a method in accordance with an embodiment of
the invention dropped from one-half meter height onto a 10 mesh screen
and allowed to dry;
[0051] Figure 6 is a photo showing the dried stackable solid in
isolation
from the screen obtained by using a method in accordance with an
embodiment of the invention;
[0052] Figure 7 is a photo showing the granulated aggregate in being
dropped into water;
[0053] Figure 8 is a photo showing the aggregate of figure 7 settling in
water; and
[0054] Figure 9 is a photo showing a dried aggregated structure that
had been submerged in water for 10 days and capable of supporting a brick
thereon.
DETAILED DESCRIPTION
[0055] Reference will be made below in detail to exemplary
embodiments of the invention, examples of which are illustrated in the
accompanying drawings. Wherever possible, the same reference numerals
used throughout the drawings refer to the same or like parts.
[0056] Examples
[0057] Example 1 - Binder formation
[0058] To examine the formation of binders, various combinations of
anionic and cationic components were tested. Anionic components were
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selected from commercial anionic flocculants and the cationic components
were cationic coagulants with or without a cationic flocculant.
[0059] As the anionic component, four commercial anionic polymer
flocculants were evaluated:
(a) a 35wt.% and a 46 wt.% sodium acrylate/acrylamide high
molecular weight copolymer.
(b) two, 40wt. % calcium diacrylate/acrylamide copolymers, medium
and high molecular weights.
[0060] As the cationic component, four commercial polymer coagulants
and one cationic flocculant were evaluated;
(a) a low and high molecular weight diallyl/dimethyl/ammonium
chloride (DADMAC) copolymer, both 20% actives.
(b) a low and high molecular weight dimethylamine/epichlorohydrin
copolymer (DMA/EPI) both 49% actives. (a) and (b) are considered
to be coagulants in water treatment.
(c) a lOwt.% quaternary/acrylamide cationic dry flocculant.
[0061] To demonstrate the formation of the binder alone, 39 ml of
water was placed in a clear container and 5.8 ml of a 0.4% solution of the
high molecular weight, 46wt.% anionic copolymer flocculant was added with
mixing. Then, 3 ml of a 0.69% (active) high molecular DMA/EPI solution
was added with mixing.
[0062] As shown in figures 1 and 2, a white haze formed immediately
(see figure 1) upon initial mixing of the anionic copolymer flocculant and
high molecular weight DMA/EPI solution and with continued stirring the haze
coalesced to form an insoluble white cocoon (see figure 2).
Date Recue/Date Received 2020-09-11
[0063] The above example demonstrates that the formation of the
binder alone can be generated by placing in an amount of water that is
contained in the sample of tailings being aggregated (sample weight less
weight of solids), adding to the water a volume of anionic polymer solution
(with mixing). Then adding to the container, with rapid mixing, a volume of
high-molecular-weight cationic coagulant solution. With rapid mixing a white
haze will quickly develop. As mixing continues the haze coalesces into a
white, insoluble cocoon-like deposit in clear water.
[0064] When the ratio of anionic to cationic disclosed herein is used,
the haze will quickly disappear and the cocoon forms. This test or similar
tests can be used to determine a ratio and quantity of the reactants to
produce the binder.
[0065] Example 2 - Treatment of Tailings
[0066] Figures 3 to 9 show the treatment of the 34.8 % fine tailing
solids to produce granules and aggregate structure. Other MFT samples
have 25% and 33.8% solids. . The two FFT samples were 11% and 12.4%
solids. All of the additional four fine tailings produced granulated and
aggregated tailings at the disclosed dosages.
[0067] A 50 ml sample of the undiluted 34.8% solids MFT (a specific
gravity of 1.2) was placed in a clear container. 5.8 ml of a 0.4% solution of
the high molecular weight, 46 wt. .% anionic copolymer flocculant was added
with vigorous hand stirring, until the sample began to express coloured
water. The sample at this point was paste-like. The dosage of anionic
copolymer flocculant was 1,115 g/ton (i.e. 1,115 ppm) of MFT solids.
[0068] Next, 3 ml of a 0.69% (active) sample of the high molecular
weight DMA/EPI coagulant, again with vigorous hand stirring. Shortly after
mixing began, the consistency of the sample began to visually change,
developing a gritty sand-like character. The formation of granules could be
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clearly seen. As mixing continued, the mix began to sound like stirring sand.
Mixing was continued until no more change in consistency was noted.
Colourless (i.e. no residual oil), clear water began to drain from the sample.
Some granules were observed leaving the aggregated mass with the draining
water but these granules immediately settled and were easily captured and
reincorporated into the aggregated mass. The dosage of the DMA/EPI
polymer actives was 995g/ton of MFT solids.
[0069] At this point the sample was a free-standing mass. Figure 3
shows the wet aggregated structure pushed by a spatula up the wall of the
container, with the container angled to drain more clear water. This clear
water (which is the water not bound within the swollen clay particles) is
vicinal water that was released from the aggregated structure and as can be
seen, within the vicinal water there is a small amount of intact granules
which importantly do not disperse in the vicinal water and are heavy.
[0070] These solids are stackable as the solids, and when left to dry,
become a basalt-like 'rock'. If immersed in water the 'rock' does not
disintegrate. Figure 4 shows a deposit produced according to one
embodiment of the method of the invention which was dried and then re-
submerged in water.
[0071] Example 3 - Treatment of Tailings
[0072] The conditions of Example 2 were repeated, but in this instance
the 5.8 ml of anionic flocculant was diluted with 12 ml of water (e.g.
reclaim)
before adding the flocculant to the MFT sample. This created 25% MFT and
reduced the mixing energy required to thoroughly mix the flocculant to
produce the paste material and to achieve vicinal water break-out. The 3 ml
of coagulant solution was then added with mixing and the granulated
aggregated structure was again produced, draining clear water. This
structure centrifuged easily to a solid that does not disintegrate in water.
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[0073] Example 4 - Treatment of Tailings
[0074] The conditions of Example 1 were repeated, but with 900g of
34.8% MFT in the smaller bowl of a MixMaster using its double cage-blades
for intensive mixing. After the aggregate was produced, it was dropped from
1.2 meter height onto a 10 mesh screen, drainage collected, and the
aggregated structure sitting on the screen left to dry, as shown in figure 5.
Figure 5 demonstrates the stability of the granulated aggregated structure
when wet. On the other hand a typical flocced structure would adhere to
and/or fall through the screen. The granulated aggregate according to the
present disclosure is supported by the screen and does not fall through the
screen.
[0075] Figure 6 shows the same dried granulated aggregated structure
of figure 5, but now removed from the screen. As shown, the granulated
aggregated structure did not penetrate nor adhere to the screen.
[0076] Figures 7 and 8 show the granulated aggregate being dropped
into and descending through the water.
[0077] Figure 9 shows a granulated aggregated structure, that had
been dried and then submerged in water for 10 days and is capable of
supporting a brick.
[0078] Discussion
[0079] The present disclosure describes formation of a binder that
granulates, aggregates and structures the fine clay particles from tailings.
Unlike current practices in oil sands operations this granulation process for
fine clay particles does not require the incorporation of sand.
[0080] In one embodiment, granulation is produced in a fine clay
tailings slurry by the sequential addition of two water soluble organic
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polymers that react to form in situ a granulating binder. This binder
granulates the fine tailings particles. The granulated tailings particles
aggregate to form a structure that can be stacked, centrifuged, or sub-
aqueously deposited without re-release of fines to process or to the
environment.
[0081] The Examples above clearly demonstrate methods to produce a
granulated, draining, semi-solid from a mineral slurry. In particular, all the
tested FFT and MFT responded similarly in the formation of a granular
deposit. The dosage levels of binder required to produce granular
aggregation were essentially the same relative to tailings solids.
[0082] The present disclosure demonstrates the binder's ability to
handle different sources of fine tailings. In one embodiment, the only
significant difference in granulation and structuring of all these fine
tailings
was the intensity of mixing required with higher slurry viscosity.
[0083] Accordingly, the present invention relates, in one embodiment,
relates to a method of producing a granulated, draining, semi-solid from a
mineral slurry. In one aspect, the invention relates to a method for
producing a granulated aggregate from an aqueous, dispersed slurry from an
oil sands operation comprising:
[0084] (a) providing an aqueous, dispersed slurry from an oil sands
operation (FFT or MFT) comprising slurrying water, solid mineral components
and possibly organic components such as bitumen;
[0085] (b) adding to the dispersed slurry of (a) sufficient quantities
of
a water solution of an anionic polymeric flocculant, such addition resulting
in
a paste structure that begins to release slurry water. In one aspect, high-
solids tailings slurries may require intense mixing to achieve the paste
structure.
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[0086] (c) adding, with mixing, to the paste structure of (b) a cationic
coagulant, such addition resulting in the in-situ formation of a granulating
binder that converts the paste structure into a gritty, stiff, draining, free-
standing granulated aggregate.
[0087] The granular nature of the produced free-standing aggregate
resembles that of a structure of wet, course beach sand. Any granules
leaving with the clear, initially-draining water are clearly visible and fall
instantly for easy recovery and re-addition to the aggregate.
[0088] At conventional dosages, the anionic flocculant will flocculate
the suspended solids. The anionic flocculant dosage needed to produce
flocced material is around 450 g/ton of tailing solids. At an effective dosage
for producing the binder, the anionic flocculant will produce a paste-like
deposit, releasing water. According to the present embodiment, when an
excess amount of anionic flocculant is selected (i.e. greater than about 250
g/ton of tailing solids), only then does the material become a desired paste-
like deposit. Therefore, the paste-like material is a dispersed material and
is
obtained when the amount of the anionic flocculant that is used is in excess
of the amounts typically used to flocculate mineral solids.
[0089] In one embodiment, the desired amount of anionic flocculant is
greater than about 450 g/ton of tailing solids. In another embodiment, the
desired amount of anionic flocculant is greater than about 1000 g/ton of
tailing solids.
[0090] In one embodiment, the anionic flocculant is a high-molecular-
weight anionic flocculant. In one embodiment, the anionic flocculant is an
anionic polymeric flocculant. In one embodiment, the anionic flocculant is a
copolymer or terpolymer anionic flocculant or is a high-molecular-weight
copolymer or terpolymer anionic flocculant.
Date Recue/Date Received 2020-09-11
[0091] As would be understood, the term anionic polymer can mean a
homopolymer of an anionic monomer or a copolymer of an anionic monomer
and a nonionic monomer. The term anionic terpolymer could be understood
to mean a polymer of two anionic monomers (e.g. sodium acrylate and
calcium diacrylate) and a nonionic monomer (e.g. acrylamide).
[0092] In one aspect, the anionic flocculant can be a water-soluble,
high-molecular-weight acrylate/acrylamide-type copolymer or terpolymer.
In one aspect, the anionic flocculant is a commercial dry anionic flocculant,
Zetag 4145 by Solenis LLC of Wilmington DE USA. Zetag 4145 is a 46 wt.%
sodium acrylate/acrylamide copolymer in dry form. In one embodiment, the
dosage of Zetag 4145 used in the Examples was 1,115 g/per ton of MFT
solids.
[0093] In one embodiment, the cationic coagulant is a cationic
polymeric coagulant. While not wishing to be bound by any particular
theory, Applicant believes that, if used in the desired amounts, the cationic
coagulant is able to convert the anionic flocculant-treated and paste-like
material to granules. Thus, in certain embodiments the use of the desired
amounts of the cationic coagulant means a dosage in excess of what is
known in the water treatment industry for usual coagulation (which is about
25 ppm). In one aspect, the commercial liquid cationic coagulant in these
tests was Floquat FL 3249 by SNF Inc. of Riceboro, GA USA. Floquat FL
3249 is a 49% actives dimethylamine/epichlorohydrin viscous liquid
copolymer. The dosage of DMA/EPI actives was 995g (active)/ton of MFT
solids.
[0094] In one aspect, the commercial dry cationic copolymer flocculant
in these tests was Zetag 7563 supplied by Solenis LLC. It is a supplement to
the DMA/EPI, as described.
[0095] Using the components as disclosed in the Examples, an
effective granulation, aggregation and structuring was developed when the
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anionic copolymer was added to the tailings first. In one aspect, the addition
sequence of the anionic constituent first, cationic constituent second, is one
preferred addition sequence according to an embodiment of the invention.
However, in another aspect, the addition sequence could be the cationic
constituent first and the anionic constituent second.
[0096] In one aspect, the sufficient dosage (in g/ton tailing solids) of
high-molecular-weight anionic flocculant to produce the binder for aggregate
formation (and to begin water release) has been found to be in the range of
about 1.5 to 2 times that of anionic flocculant required in conventional
tailings flocculation which is about 250-500 g/ton of tailing solids. In some
aspects, the required dosage (g/ton tailing solids) of high-molecular-weight
organic cationic coagulant (active) is in the same g/ton range as that of the
anionic flocculant.
[0097] From the Examples, the performance of the anionic component
copolymers as binder reactants, one preferred embodiment was the 46 wt.%
sodium acrylate/acrylamide copolymer, followed closely in order by the
35wt.% sodium acrylate/acrylamide copolymer, then the high molecular
weight 40 wt.% calcium diacrylate/acrylamide copolymer, then the medium
molecular weight 40 wt.% calcium diacrylate/acrylamide copolymer.
[0098] Using the components as disclosed in the Examples, the high
molecular weight DMA/EPI coagulant was the most effective in granulation,
aggregation and structuring the MFT, regardless of which one of the anionic
copolymers was used.
[0099] The 10 wt.% cationic flocculant was not effective in replacing
the DMA/EPI in the initial formation of the granular structure (results not
shown). However, if 2.5 wt.% of the cationic flocculant was blended with
the 97.5 wt.% DMA/EPI product (effectively creating a 5 wt.%
flocculant/95wt.% DMA/EPI actives blend), granulation was maintained. In
one embodiment, this blend reduced the amount of granules that left the
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deposit with the initial drainage water and appeared to strengthened the
structure of the deposit.
[00100] Materials handling in oil sands processes, particularly of dry
flocculants, is often a problem. In some embodiments, handling problems
with the addition of another flocculant to this process can be avoided if the
dry cationic flocculant product is blended with the DMA/EPI product, adding
water to the blend to produce a 40wt.% actives product. Without being
limited to any particular theory it is believed that the dry flocculant will
essentially dissolve in the diluted DMA/EPI and therefore simplifying the
process of applying the cationic component as used in the Examples.
[00101] The present inventor has surprisingly discovered that water-
soluble organic polymers can be added sequentially to FFT or MFT, forming a
water-insoluble or granulating binder that produces granules in-situ from
clay tailings. In preferred embodiments, the organic polymers are
commercial water treatment organic polymers. The formed granules are
easily visible and aggregate to form a draining semi-solid structure that can
be wet-stacked.
[00102] The semi-solid wet structure can be formed directly from high-
solids tailings without dilution, or from dilute tailings with initial
increased
water release. The structure of this deposit releases clear water initially
and
continues to release oil-free, clear, solids-free water under (simulated)
stacked-compression.
[00103] Any granulated tailings released during initial dewatering of the
aggregated structure settle instantly from the water and are easily
recovered. Residual bitumen is bound in the granules and aggregate. If
taken to dryness, the structure resembles basalt and will not collapse in
water. The semi-solid wet-stacked structure is not disrupted by freeze-
thawing, as the granules and structure remain intact.
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[00104] Importantly, the wet granulated structure can also be
centrifuged for additional water release. Importantly, the granulated
structure can be sub-aqueously deposited without release of fines while
being deposited, or over time.
[00105] In some embodiments, the granulated structure could be
subjected to compression and drying sufficient to produce the basalt-like
structure of desired stack thicknesses.
[00106] Beneficially, sand-free fluid tailings of any solids content
could
be pumped to a mined-out area of the mine pit and there treated
continuously, producing wet, free-draining solids and clear water. The solids
could be conveyor-drained and stacked with conventional mining equipment
for mine site reclamation, never to be handled again, which is in contrast to
current industry practice. Existing centrifuge applications would be
enhanced. In some embodiments, sub-aqueous deposition may well be the
economic choice.
[00107] In some embodiments, this sub-aqueous deposition could be
done with continuous processing of MFT and deposition in an oil sands
mined-out pit for permanent sequestering of oil sands fines. Importantly, no
further handling would ever be required.
[00108] According to an embodiment, the granulation process of the
present disclosure may sequester process water contaminants such as
arsenic (metalloids), selenium (polyatomic non-metals), and/or
naphthenates (surfactants) within the granulated and aggregated tailings
structure. These substances can be considered contaminants and therefore,
undesirable for various reasons (e.g. environmental impact). Without being
limited to any particular theory, the high charge cationic coagulant
component (e.g. the second step in the formation of the binder) will
insolublize and sequester arsenic, selenium, and naphthenates, in the
formed granulated solids.
19
Date Recue/Date Received 2020-09-11
[00109] The embodiments of the present application described above
are intended to be examples only. Those of skill in the art may effect
alterations, modifications and variations to the particular embodiments
without departing from the intended scope of the present application. In
particular, features from one or more of the above-described embodiments
may be selected to create alternate embodiments comprised of a
subcombination of features which may not be explicitly described above. In
addition, features from one or more of the above-described embodiments
may be selected and combined to create alternate embodiments comprised
of a combination of features which may not be explicitly described above.
Features suitable for such combinations and subcombinations would be
readily apparent to persons skilled in the art upon review of the present
application as a whole. Any dimensions provided in the drawings are
provided for illustrative purposes only and are not intended to be limiting on
the scope of the invention. The subject matter described herein and in the
recited claims intends to cover and embrace all suitable changes in
technology.
Date Recue/Date Received 2020-09-11
