CA3010053A1 - Methods of tailings treatment - Google Patents

Abstract

The present embodiments generally relate to methods for the treatment of tailings, e.g., oil sands tailings, e.g., mature fine tailings. This in particular may include methods comprising the use of one or more polymers and/or one or more flocculants, wherein said method may comprise a pH adjustment and may result in improved performance of said one or more polymers and/or said one or more flocculants.

Description

METHODS OF TAILINGS TREATMENT
FIELD OF THE ART
[001] The present disclosure generally relates to improved methods of treating tailings, e.g., methods comprising the dewatering of tailings such as oil sands tailings.
BACKGROUND

[002] Bituminous sands, also referred to as oil sands, are a type of petroleum deposit. Oil sands typically contain naturally occurring mixtures of sand, clay, water, and a dense, extremely viscous form of petroleum technically referred to as bitumen (or colloquially "tar" due to their similar appearance, odor, and color). Oil sands may be found in large quantities in many countries throughout the world, most abundantly so in Canada and Venezuela.
Oil sand deposits in northern Alberta in Canada (Athabasca oil sands) are thought to contain approximately 1.6 trillion barrels of bitumen, and production from oil sands mining operations is expected to reach 1.5 million barrels of bitumen per day by 2020.

[003] Oil sands reserves are an important part of the world's oil reserves, particularly as higher oil prices and new technology enable oil sands reserves to be profitably extracted and upgraded to usable products. Oil sands are often referred to as unconventional oil or crude bitumen, in order to distinguish the bitumen extracted from oil sands from the free-flowing hydrocarbon mixtures known as crude oil traditionally produced from oil wells.

[004] Conventional crude oil may be extracted from the ground by drilling oil wells into a petroleum reservoir and allowing oil to flow into them under natural reservoir pressure, although artificial lift and techniques such as water flooding and gas injection may be required to maintain production as reservoir pressure drops toward the end of a field's life. Since extra-heavy oil and bitumen flow very slowly, if at all, towards producing wells under normal reservoir conditions, the sands may be extracted by strip mining or the oil made to flow into wells by in situ techniques that reduce the viscosity, such as by injecting steam, solvents, and/or hot air into the sands. These processes may use more water and may require larger amounts of energy than conventional oil extraction, although many conventional oil fields also typically require large amounts of water and energy to achieve good rates of production.

[005] Water-based oil sand extraction processes generally include ore preparation, extraction, and tailings treatment stages wherein a large volume of solids-laden aqueous tailings may generally be produced.

[006] These tailings may generally be referred to as oil sands process tailings, or oil sands tailings. These tailings may require solid-liquid separation in order to efficiently recycle the water and reduce the volume of the tailings. In many processes, these oil sands tailings are pumped to large settling ponds (or tailings ponds).

[007] In tailings ponds, the process water, unrecovered hydrocarbons, and minerals generally settle naturally to form different strata. The upper stratum is usually primarily water that may be recycled as process water to the extraction process. The lower stratum generally contains the heaviest materials, mostly sand, which settle to the bottom of the pond. The middle stratum, often referred to as "mature fine tailings" ("MFT"), generally includes water and hydrophilic and biwetted ultrafine solids, mainly clays and other charged silicates and metal oxides, that tend to form stable colloids in water and exhibit a very slow settling and dewatering behavior, resulting in tailing ponds that may take several years to manage.

[008] The composition of mature fine tailings tends to be highly variable.
Near the top of the stratum the mineral content may be about 10% by weight and over time may consolidate and comprise up to 50% by weight of the materials contained at the bottom of the stratum. Overall, mature fine tailings may have an average mineral content of about 30% by weight. While fines may generally be the dominant particle size fraction in the mineral content, the sand content may be 15% by weight of the solids and the clay content may be up to 75% by weight of the solids, reflecting the oil sand ore and extraction process. Additional variation may result from the residual hydrocarbon which may be dispersed in the mineral or may segregate into mat layers of hydrocarbon. The mature fine tailings in a pond may not only contain a wide variation of compositions distributed from top to bottom of the pond, but also may contain pockets of different compositions at random locations throughout the pond. Additionally, mature fine tailings generally behave as a fluid-like colloidal material.

[009] In treatment processes for dewatering oil sands tailings, clays and ultra-fine solids are often challenging to capture and in many instances may remain suspended in the treated water which will be recycled back to the extraction process. These solids may be detrimental to bitumen recovery, and as such, maximizing separation of the fines from the water during tailings treatment is of general importance. As such, improving the treatment of tailings is of great interest.
BRIEF SUMMARY

[0010] The present embodiments generally pertain to a method of treating tailings which method includes the use of one or more flocculants in order to improve flocculant performance, wherein said method comprises a pH adjustment of a solution comprising said tailings, wherein said pH
adjustment occurs not before a first introduction of one or more polymers and not after completion of mechanical dewatering. In some embodiments, said pH adjustment may be effected by the introduction of carbon dioxide. In some embodiments, said pH
adjustment may be effected by introducing an acid and/or highly acidic dispersant, coagulant, polymer, flocculant, monomers that may polymerize to form a polymer, or any other process additive product. In some embodiments, said method may comprise a plurality of introductions of one or more polymers, e.g., said plurality of introductions may comprise a plurality of introductions occurring at one time-point in said method, and/or said plurality of introductions may comprise at least one introduction occurring at a first time-point of said method, and at least one introduction occurring at a second time-point of said method, wherein said first time-point and second time-point are different from one another. In some embodiments, said method may comprise the introduction of several different flocculants, e.g., said flocculants may comprise a polymer comprising one or more monomers of the following: acryloyloxy ethyl trimethyl ammonium chloride ("AETAC"); methacryloyloxyethyltrimethylammonium chloride;
methacrylamidopropyltrimethylammonium chloride ("MAPTAC");
acrylamidopropyltrimethylammonium chloride;
methacryloyloxyethyldimethylammonium sulfate; dimethylaminoethyl acrylate; dimethylaminopropylmethacrylamide; Q6;
Q6o 4;
diallyldimethylammonium chloride ("DADMAC"); calcium diacrylate ("CDA");
acrylamide;
acrylic acid; any monomer substituted with a carboxylic acid group or salt thereof; 2-acrylamido-2-methylpropane sulfonic acid ("AMPS"); ethylene oxide; propylene oxide;
functionalized ethylene oxide; epoxide; functionalized propylene oxide; epoxy or glycidyl ether functionalized hydrophobic monomers; 1 ,2-epoxy tetradecane; 2-ethylhexylglycidyl ether; 2, 2, 3, 3, 4, 4, 5, 5-octafluoropentyl ether; benzyl glycidyl ether; 4-nonylphenyl glycidyl ether;
silane- or siloxane-functionalized glycidyl ethers; silane or siloxane-functionalized monomers; 3-glycidyloxypropyl polydimethyl siloxane; 3-glycidyloxypropyl trimethoxysilane; 3-glycidoxypropyldimethylethoxysilane; alkylene oxide; olefin oxide; aliphatic, cycloaliphatic or mixed aliphatic/cycloaliphatic alkylene oxide; alkylene oxide substituted by one or more aromatic radicals; 1,2-epoxybutane; 2,3-epoxybutane; the epoxypentanes; the epoxyhexanes; the epoxyoctanes; the epoxydecanes; the epoxydodecanes; 2,4,4-trimethy1-1,2-epoxypentane; 2,4,4-trimethy1-2,3-epoxypentane; cyclohexylepoxythane; 7-oxabicyclo[4.1.0]heptane;

oxabicyclo[3.1.0]hexane; 3-methy1-6-oxabicyclo[3.1.0]hexane; 4-ethy1-6-oxabicyclo[3.1.0]hexane; styrene oxide; 1 -phenyl- 1 ,2-epoxypropane; 1,2-butylene oxide; 2,3-butylene oxide; the epoxypentanes, the epoxyhexanes; 2,3-epoxyheptane; nonene oxide; 5-butyl-3,4-epoxyoctane; 1 ,2-epoxydodecane; 1,2-epoxyhexadecane; 1 ,2-epoxyoctadecane; 5-benzy1-2,3-epoxyheptane; 4-cyclo-hexy1-2,3-epoxypentane; chlorostyrene oxide; styrene oxide; ortho-, meta-, and para-ethylstyrene oxide; glycidyl benzene; the oxabicycloalkanes;
alkyl-substituted oxabicycloalkanes, e.g., 7-oxabicyclo[4.1.0]heptane; oxabicyclo[3.1.0]hexane;
4-propy1-7-oxabicyclo[4.1.0]heptane; and/or 3-amy1-6-oxabicyclo[3.1.0Thexanel.

[0011] In some embodiments, the pH of said tailings may be adjusted more than one time during said method. In some embodiments, the pH of said tailings before said pH
adjustment may be about 6.60 or higher. In some embodiments, the pH of said tailings before said pH adjustment may be about 6.60 or higher, 6.70 or higher, 6.80 or higher, 6.90 or higher, 7.00 or higher, 7.10 or higher, 7.20 or higher, 7.30 or higher, 7.40 or higher, 7.50 or higher, 7.60 or higher, 7.70 or higher, 7.80 or higher, 7.90 or higher, 8.00 or higher, 8.10 or higher, 8.20 or higher, 8.30 or higher, 8.40 or higher, 8.50 or higher, 8.60 or higher, 8.70 or higher, 8.80 or higher, 8.90 or higher, 9.00 or higher, 9.10 or higher, 9.20 or higher, 9.30 or higher, 9.40 or higher, 9.50 or higher, 9.60 or higher, 9.70 or higher, 9.80 or higher, 9.90 or higher, or 10.00 or higher. In some embodiments, the pH of said tailings after said pH adjustment may be about 6.50 or lower. In some embodiments, the pH of said tailings after said pH adjustment may be about 6.50 or lower, 6.40 or lower, 6.30 or lower, 6.20 or lower, 6.10 or lower, 6.00 or lower, 5.90 or lower, 5.80 or lower, 5.70 or lower, 5.60 or lower, 5.50 or lower, 5.40 or lower, 5.30 or lower, 5.20 or lower, 5.10 or lower, 5.00 or lower, 4.90 or lower, 4.80 or lower, 4.70 or lower, 4.60 or lower, 4.50 or lower, 4.40 or lower, 4.30 or lower, 4.20 or lower, 4.10 or lower, or 4.00 or lower.

[0012] In some embodiments, said method may comprise the following steps: a. a first introduction of one or more polymers; b. flocculation; c. floc conditioning;
d. mechanical dewatering; e. solid-liquid (cake-centrate) separation; and f. cake deposition for continued cake drying and/or dewatering. In some embodiments, said method may comprise the following steps:
a. a first introduction of one or more polymers; b. flocculation; c. floc conditioning; d.
mechanical dewatering; e. solid-liquid (cake-centrate) separation; and f. cake deposition for continued cake drying and/or dewatering; and further wherein said one or more polymers begin to mix with the tailings prior to any pH adjustment. In some embodiments, said method may comprise steps a.-f., and may additionally comprise a plurality of polymer introductions. In some embodiments, one or more additional polymer introductions may occur during and/or after step a. and not after step d. In some embodiments, the pH of said tailings may be adjusted not before step a. and not after step d. In some embodiments, said pH adjustment may occur during and/or after a first introduction of one or more polymers. In some embodiments, said pH adjustment may occur before, during, and/or after flocculation. In some embodiments, said pH adjustment may occur before, during, and/or after floc conditioning. In some embodiments, said pH
adjustment may occur before or during mechanical dewatering, e.g., centrifugation, thin lift, and/or the introduction of one or more thickeners. In some embodiments, said method may comprise introduction of one or more flocculants. In some embodiments, said tailings may comprise oil sands tailings; mature fine tailings; fluid fine tailings;
tailings from coal mining, copper mining, aluminum mining, nickel mining, gold mining, and/or mineral processing; and/or in-process tailings. In some embodiments, said tailings may comprise oil sands tailings. In some embodiments, said tailings may comprise mature fine tailings.

[0013] In some embodiments, said method may comprise centrifugation as a mechanical dewatering step. In some embodiments, said method may comprise the introduction of cationic, neutral or anionic flocculants or a combination of any of the foregoing, e.g., said flocculants may comprise one or more polymers, comprising one or more monomers of the following:
acryloyloxy ethyl trimethyl ammonium chloride ("AETAC");
methacryloyloxyethyltrimethylammonium chloride;
methacrylamidopropyltrimethylammonium chloride ("MAPTAC"); acrylamidopropyltrimethylammonium chloride;

methacryloyloxyethyldimethylammonium sulfate; dimethylaminoethyl acrylate;
dimethylaminopropylmethacrylamide; Q6; Q6o 4; diallyldimethylammonium chloride ("DADMAC"); calcium diacrylate ("CDA"); acrylamide; acrylic acid; any monomer substituted with a carboxylic acid group or salt thereof; 2-acrylamido-2-methylpropane sulfonic acid ("AMPS"); ethylene oxide; propylene oxide; functionalized ethylene oxide;
epoxide;
functionalized propylene oxide; epoxy or glycidyl ether functionalized hydrophobic monomers;
1 ,2-epoxy tetradecane; 2-ethylhexylglycidyl ether; 2, 2, 3, 3, 4, 4, 5, 5-octafluoropentyl ether;
benzyl glycidyl ether; 4-nonylphenyl glycidyl ether; silane- or siloxane-functionalized glycidyl ethers; silane or siloxane-functionalized monomers; 3-glycidyloxypropyl polydimethyl siloxane;
3-glycidyloxypropyl trimethoxysilane; 3-glycidoxypropyldimethylethoxysilane;
alkylene oxide;
olefin oxide; aliphatic, cycloaliphatic or mixed aliphatic/cycloaliphatic alkylene oxide; alkylene oxide substituted by one or more aromatic radicals; 1,2-epoxybutane; 2,3-epoxybutane; the epoxypentanes; the epoxyhexanes; the epoxyoctanes; the epoxydecanes; the epoxydodecanes;
2,4,4-trimethy1-1,2-epoxypentane; 2,4,4-trimethy1-2,3-epoxypentane;
cyclohexylepoxythane; 7-oxabicyclo[4.1.0]heptane; 6-oxabicyclo[3.1.0]hexane; 3-methy1-6-oxabicyclo[3.1.0]hexane; 4-ethy1-6-oxabicyclo[3.1.0]hexane; styrene oxide; 1 -phenyl- 1 ,2-epoxypropane;
1,2-butylene oxide; 2,3-butylene oxide; the epoxypentanes, the epoxyhexanes; 2,3-epoxyheptane; nonene oxide; 5-butyl-3,4-epoxyoctane; 1 ,2-epoxydodecane; 1,2-epoxyhexadecane; 1 ,2-epoxyoctadecane; 5-benzy1-2,3-epoxyheptane; 4-cyclo-hexy1-2,3-epoxypentane;
chlorostyrene oxide; styrene oxide; ortho-, meta-, and para-ethylstyrene oxide; glycidyl benzene; the oxabicycloalkanes; alkyl-substituted oxabicycloalkanes, e.g., 7-oxabicyclo[4.1.0]heptane;
oxabicyclo[3.1.0]hexane; 4-propy1-7-oxabicyclo[4.1.0]heptane; and/or 3-amy1-6-oxabicyclo[3.1.0Jhexane.].

[0014] In some embodiments, the pH of said tailings may not be adjusted prior to a first introduction of one or more polymers. In some embodiments, the pH of said tailings prior to introduction of one or more polymers may be or may be adjusted to between about 7.0 to about 10Ø In some embodiments, said method may comprise a centrate solids content of 1.00% or less, 0.95% or less, 0.90% or less, 0.85% or less, 0.80% or less, 0.75% or less, 0.70% or less, 0.65% or less, 0.60% or less, 0.55% or less, 0.50% or less, 0.45% or less, 0.40% or less, 0.35%
or less, 0.30% or less, 0.25% or less, 0.20% or less, 0.15% or less, or 0.10%
or less that results from treating said tailings. In some embodiments, said method may comprise a cake solids content of 40.0% or more, 40.5% or more, 41.0% or more, 41.5% or more, 42.0%
or more, 42.5% or more, 43.0% or more, 43.5% or more, 44.0% or more, 44.5% or more, 45.0% or more, 45.5% or more, 46.0% or more, 46.5% or more, 47.0% or more, 47.5% or more, or 48.0% or more, 48.5% or more, 49.0% or more, 49.5% or more, 50.0% or more, 50.5% or more, 51.0% or more, 51.5% or more, 52.0% or more, 52.5% or more, 53.0% or more, 53.5% or more, 54.0% or more, 54.5% or more, 55.0% or more, 55.5% or more, 56.0% or more, 56.5% or more, 57.0% or more, 57.5% or more, 58.0% or more, 58.5% or more, 59.0% or more, 59.5% or more, 60.0% or more, 60.5% or more, 61.0% or more, 61.5% or more, 62.0% or more, 62.5% or more, 63.0% or more, 63.5% or more, 64.0% or more, 64.5% or more, or 65.0% or more that results from treating said tailings. In some embodiments, said method may comprise introduction of a polymer comprising acrylamide monomers. In some embodiments, said method may comprise introduction of a copolymer comprising acrylamide monomers and acrylic acid monomers. In some embodiments, said method may comprise introduction of a polymer comprising acrylic acid monomers. In some embodiments, said method may comprise introduction a polymer comprising acrylic acid monomers, wherein said acrylic acid monomers comprise a monomer percentage of 10% or more, 15% or more, 20% or more, 25% or more, 30% or more, 35% or more, 40% or more, 45% or more, 50% or more, 60% or more, 70% or more, 80% or more, or 90% or more, 95% or more, 99% or more. In some embodiments, said method may comprise introduction of a polymer comprising acrylic acid monomers, wherein said acrylic acid monomers comprise a monomer percentage of 100%.

[0015] In some embodiments, said method may comprise introduction of a polymer, e.g., DPAM
at a dose on a weight ratio of polymer to solids (dry basis) of 1 ppm or less, 10 ppm or less, 25 ppm or less, 50 ppm or less, 50 ppm or more, 100 ppm or more, 200 ppm or more, 300 ppm or more, 400 ppm or more, 500 ppm or more, 600 ppm or more, 700 ppm or more, 800 ppm or more, 900 ppm or more, 1000 ppm or more, 1100 ppm or more, 1200 ppm or more, 1300 ppm or more, 1400 ppm or more, 1500 ppm or more, 1600 ppm or more, 1700 ppm or more, 1800 ppm or more, 1900 ppm or more, or 2000 ppm or more.

[0016] In some embodiments a DPAM or other polymer is dosed based on weight ratio of polymer (on a dry basis) to MFT (or clay) solids (on a dry basis. g of polymer/g of clay = the ppm polymer dose (wherein the ppm ranges are polymer dose ranges, not polymer application solution concentrations)). Dry polyacrylamide ("DPAM") may be synthesized by many methods, including those in the working examples, and generally the synthesized DPAM is well over 1 million Da. The polymer, e.g., DPAM, can be added to the MFT as a solution of any concentration. In some embodiments a solution containing 0.5-1.5% of polymer, e.g., DPAM, is used. In other embodiments a solution comprising a very low or higher concentration of DPAM
or other polymer may be used. In some embodiments the DPAM is added in dry form ¨90%. In some embodiments, said one or more polymers and/or said one or more flocculants may begin to mix with said tailings before said pH adjustment occurs. In some embodiments, said introduction may comprise injection, pouring, and/or dripping. Furthermore, the present application generally encompasses a product produced by any of the methods described herein.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

[0017] Figure 1 presents data related to an experiment that evaluated the effect of the final pH of a solution comprising tailings on cake and centrate solids, wherein said solution was treated in accordance with Example 1. The black circles represent cake solids content values, and the black triangles represent centrate solids content values.

[0018] Figure 2 presents data related to an experiment that evaluated the effect of various doses of a polymer used to treat a solution comprising tailings on cake and centrate solids, wherein said solution was treated accordance with Example 2. The black circles represent cake solids content values, and the black triangles represent centrate solids content values.

[0019] Figure 3 presents data related to an experiment that evaluated the effect of final dose of a polymer used to treat a solution comprising tailings on cake and centrate solids, wherein said solution was treated accordance with Example 2. The black circles represent cake solids content values, and the black triangles represent centrate solids content values.

[0020] Figure 4 presents data related to an experiment that evaluated the effect of the initial pH
of a solution comprising tailings on the cake solids content, wherein said solution was treated in accordance with Example 3.

[0021] Figure 5 resents data related to an experiment that evaluated the effect of the final dose of a polymer used to treat a solution comprising tailings on cake and centrate solids, wherein said solution was treated in accordance with Example 4. The black circles represent cake solids content values, and the black triangles represent centrate solids content values.

[0022] Figure 6 presents data related to an experiment that evaluated the effect of the final dose of a polymer used to treat a solution comprising tailings on cake and centrate solids, wherein said solution was treated in accordance with Example 4. The black circles represent cake solids content values, and the black triangles represent centrate solids content values.

[0023] Figure 7 presents data related to an experiment that evaluated the effect of the final dose of a polymer used to treat a solution comprising tailings on cake and centrate solids, wherein said solution was treated in accordance with Example 4. The black circles represent cake solids content values, and the black triangles represent centrate solids content values.

[0024] Figure 8 presents data related to an experiment that evaluated the effect of the final dose of a polymer used to treat a solution comprising tailings on cake and centrate solids, wherein said solution was treated in accordance with Example 5. The black circles represent cake solids content values.

[0025] Figure 9 presents a contour plot demonstrating the relationship of performance with dose of a polymer and final pH of a solution comprising tailings, wherein said solution was treated in accordance with Example 5.

[0026] Figure 10 presents a plot of maximum cake solids vs. polymer molecular weight as standard viscosity in accordance with Example 6.

[0027] Figure 11 presents data related to an experiment that evaluated the effect of the final dose of a polymer used to treat a solution comprising tailings on cake and centrate solids, wherein said solution was treated in accordance with Example 7. The black circles represent cake solids content values, and the black triangles represent centrate solids content values.

[0028] Figure 12 presents data related to an experiment that evaluated the effect of the final dose of a polymer used to treat a solution comprising tailings on cake and centrate solids, wherein said solution was treated in accordance with Example 7. The black circles represent cake solids content values, and the black triangles represent centrate solids content values.

[0029] Figure 13 presents data related to an experiment that evaluated the effect of the final dose of a polymer used to treat a solution comprising tailings on cake and centrate solids, wherein said solution was treated in accordance with Example 7. The black circles represent cake solids content values, and the black triangles represent centrate solids content values.
DETAILED DESCRIPTION

DEFINITIONS

[0030] The various exemplary embodiments disclosed herein generally relate to methods for treating tailings such as oil sands tailings. In exemplary embodiments, the methods involve methods for flocculating solids in the tailings and/or methods for dewatering of the tailings.
Exemplary methods may generally comprise the use of one or more flocculants in order to flocculate solids in the tailings, in combination with adjusting the pH of a solution comprising said tailings. In exemplary embodiments, the pH adjustment is performed not before a first introduction of one or more polymer flocculants and not after completion of mechanical dewatering. The present embodiments also generally relate to a product that may be produced by any of the methods described herein.

[0031] As used herein the singular forms "a", "and", and "the" include plural referents unless the context clearly dictates otherwise. All technical and scientific terms used herein have the same meaning as commonly understood to one of ordinary skill in the art to which this invention belongs unless clearly indicated otherwise.

[0032] As used herein, the terms "tailings" and "tailings stream" generally refer to the discarded materials that may be generated in the course of extracting a valuable material from an ore.
Exemplary tailings include, but are not limited to, tailings from coal mining, copper mining, gold mining, aluminum mining, nickel mining and/or mineral processing. Exemplary tailings also include tailings from the processing of oil sands. While many of the exemplary embodiments are described with reference to oil sands tailings, it is understood that the exemplary compositions, processes, and methods are not limited to applications in oil sands tailings, but also can be applied to various other tailings. The term tailings is meant to be inclusive of but not limited to any of the types of tailings discussed herein, e.g., process oil sand tailings, in-process tailings, oil sands tailings, and the like.

[0033] The terms "process oil sand tailings", "oil sands tailings stream", "oil sands process tailings", or "oil sands tailings", generally refer to tailings that may be directly generated as bitumen is extracted from oil sands. In tar sand processing, tailings may comprise the whole tar sand ore and any net additions of process water less the recovered bitumen.

[0034] Any tailings fraction obtained from the process, such as tailings from primary separation cell, primary flotation and secondary flotation, process tailings, froth treatment tailings, and mature fine tailings or combination thereof, may be treated by the exemplary processes described herein. The tailings may comprise a colloidal sludge suspension comprising clay minerals and/or metal oxides/hydroxides. In exemplary embodiments, the tailings stream may comprise water and solids.

[0035] Tailings generally comprise mineral solids having a variety of particle sizes. Mineral fractions with a particle diameter greater than 44 microns may be referred to as "coarse"
particles, or "sand." Mineral fractions with a particle diameter less than 44 microns may be referred to as "fines" and may essentially be comprised of silica and silicates and clays that may be easily suspended in the water. Ultrafine solids, e.g., particles < 1 Jim may also be present in the tailings stream and may be primarily composed of clays. The tailings may include but are not limited to including one or more of the coarse particles, fine tailings, MFT, FFT, or ultrafine solids.

[0036] The oil sands tailings may additionally include but are not limited to including one or more of any of the tailings streams that may be produced in a process to extract bitumen from an oil sands ore. In some embodiments, the tailings may comprise paraffinic or naphthenic tailings, for example paraffinic froth tailings. The tailings may be combined into a single tailings stream for dewatering or each tailings stream may be dewatered individually.

[0037] In some embodiments, the tailings stream may be produced from an oil sands ore and may comprise water and solids, for example sand and fines. In exemplary embodiments, the tailings stream may comprise at least one of the coarse tailings, fluid fine tailings, MFT, fine tailings, and ultrafine tailings. In some embodiments, the processes may be used to treat ultrafine solids. In some embodiments, the tailings stream may comprise a fine (particle size < 44 m) content of about 10 to about 100 wt%, about 20 to about 100 wt%, about 30 to about 100 wt%, or about 40 to about 90 wt% of the dry tailings. In some embodiments, the tailings stream may comprise about 0.01 to about 5 wt% of bitumen. In some embodiments, the oil sands ore tailings stream may comprise process tailings.

[0038] Any of the above terms referencing "tailings" additionally generally comprises fluid fine tailings ("FFT") such as mature fine tailings ("MFT") from tailings ponds and fine tailings from ongoing extraction operations (for example, froth treatment tailings or thickener underflow) which may bypass a tailings pond.

[0039] As used herein, "fines" generally may refer to mineral fractions that may comprise a particle diameter less than 44 microns.

[0040] As used herein, "fluid fine tailings" or "FFT" may comprise a liquid suspension of oil sand fines in water with a solids content greater than 2%.

[0041] The term "mature fine tailings" ("MFT") generally may refer to fine tailings that may comprise a solids content of about 30-35%, and that generally may comprise almost entirely solids <44 microns. MFT generally may behave as a fluid-like colloidal material. MFT may comprise FFT with a low sand to fines ratio ("SFR"), i.e., generally less than about 0.3, and a solids content that may be generally greater than about 30%.

[0042] As used herein, "sand" generally may refer to mineral fractions that may comprise a particle diameter greater than 44 microns.

[0043] As used herein, the term "coagulant" generally may refer to an agent that may typically destabilize colloidal suspensions. Exemplary coagulants may comprise but are not limited to comprising inorganic coagulants such as aluminium sulfate ("ALS") and other metal sulfates and gypsum, organic coagulants such as polyamines and polyDADMACs, and other inorganic and organic coagulants known in the art. Exemplary coagulants may comprise highly acidic coagulants.

[0044] In some embodiments, the coagulant may comprise a poly(diallyldimethyl ammonium chloride) compound; an epi-polyamine compound; a polymer that may comprise one or more quaternized ammonium groups, such as acryloyloxyethyltrimethylammonium chloride, methacryloyloxyethyltrimethylammonium chloride, methacrylamidopropyltrimethylammonium chloride, acrylamidopropyltrimethylammonium chloride; or a mixture thereof In some embodiments, one or more inorganic coagulants may be added to the tailings stream. An inorganic coagulant may, for example, reduce, neutralize or invert electrical repulsions between particles. Exemplary inorganic coagulants may comprise but are not limited to inorganic salts such as aluminum sulfate, polyaluminum chloride, polyaluminum silica sulfate, ferric chloride, ferrous chloride, ferric sulfate, ferrous sulfate, lime, calcium chloride, calcium sulfate, magnesium chloride, or various commercially available iron or aluminum salts coagulants.

[0045] As used herein the term "nonionic monomer" generally refers to a monomer that possesses a neutral charge. Exemplary nonionic monomers may comprise but are not limited to comprising monomers selected from the group consisting of acrylamide ("AMD"), methacrylamido, vinyl, allyl, ethyl, and the like, all of which may be substituted with a side chain selected from, for example, an alkyl, arylalkyl, dialkyl, ethoxyl, and/or hydrophobic group.
In an exemplary embodiment, a nonionic monomer may comprise AMD.

[0046] As used herein, the term "anionic monomers" may refer to either anionic monomers that are substantially anionic in whole or (in equilibrium) in part, at a pH in the range of about 6.0 to about 8Ø The "anionic monomers" may be neutral at low pH (from a pH of about 2 to about 6), or to anionic monomers that are anionic at low pH.

[0047] Examples of anionic monomers may comprise but are not limited to comprising acrylic, methacrylic, maleic monomers and the like, calcium diacrylate, and/or any monomer substituted with a carboxylic acid group or salt thereof. In some embodiments, anionic monomers which may be substituted with a carboxylic acid group include, for example, acrylic acid, and methacrylic acid. In some embodiments, an anionic monomer may be a (meth)acrylamide monomer wherein the amide group has been hydrolyzed to a carboxyl group. Said monomer may be a derivative or salt of a monomer according to the embodiments. Additional examples of anionic monomers comprise but are not limited to comprising sulfonic acids or a sulfonic acid group, or both. In some embodiments, the anionic monomers may comprise a sulfonic function that may comprise, for example, 2-acrylamido-2-methylpropane sulfonic acid ("AMPS").

[0048] As used herein, the term "cationic monomer" generally refers to a monomer that possesses a positive charge. Examples of cationic monomers may comprise but are not limited to comprising acryloyloxy ethyl trimethyl ammonium chloride ("AETAC"), methacryloyloxyethyltrimethylammonium chloride, methacrylamidopropyltrimethylammonium chloride ("MAPTAC"), acrylamidopropyltrimethylammonium chloride, methacryloyloxyethyldimethylammonium sulfate, dimethylaminoethyl acrylate, dimethylaminopropylmethacrylamide, Q6, Q6o 4, and/or diallyldimethylammonium chloride ("DADMAC").

[0049] Said cationic monomers may also comprise but are not limited to comprising dialkylaminoalkyl acrylates and methacrylates and their quaternary or acid salts, including, but not limited to, dimethylaminoethyl acrylate methyl chloride quaternary salt, dimethylaminoethyl acrylate methyl sulfate quaternary salt, dimethyaminoethyl acrylate benzyl chloride quaternary salt, dimethylaminoethyl acrylate sulfuric acid salt, dimethylaminoethyl acrylate hydrochloric acid salt, diethylaminoethyl acrylate, methyl chloride quaternary salt, dimethylaminoethyl methacrylate methyl chloride quaternary salt, dimethylaminoethyl methacrylate methyl sulfate quaternary salt, dimethylaminoethyl methacrylate benzyl chloride quaternary salt, dimethylaminoethyl methacrylate sulfuric acid salt, dimethylaminoethyl methacrylate hydrochloric acid salt, dimethylaminoethyl methacryloyl hydrochloric acid salt, dialkylaminoalkylacrylamides or methacrylamides and their quaternary or acid salts such as acrylamidopropyltrimethylammonium chloride, dimethylaminopropyl acrylamide methyl sulfate quaternary salt, dimethylaminopropyl acrylamide sulfuric acid salt, dimethylaminopropyl acrylamide hydrochloric acid salt, methacrylamidopropyltrimethylammonium chloride, dimethylaminopropyl methacrylamide methyl sulfate quaternary salt, dimethylaminopropyl methacrylamide sulfuric acid salt, dimethylaminopropyl methacrylamide hydrochloric acid salt, diethylaminoethylacrylate, diethylaminoethylmethacrylate and diallyldialkylammonium halides such as diallyldiethylammonium chloride and diallyldimethyl ammonium chloride.
Alkyl groups may generally be C1-8 alkyl.

[0050] As used herein, the terms "polymer," "polymers," "polymeric," and similar terms are used in their ordinary sense as understood by one skilled in the art, and thus may be used herein to refer to or describe a large molecule (or group of such molecules) that may comprise recurring units. Polymers may be formed in various ways, including by polymerizing monomers and/or by chemically modifying one or more recurring units of a precursor polymer.
Unless otherwise specified, a polymer may comprise a "homopolymer" that may comprise substantially identical recurring units that may be formed by, for example, polymerizing, a particular monomer. Unless otherwise specified, a polymer may also comprise a "copolymer" that may comprise two or more different recurring units that may be formed by, for example, copolymerizing, two or more different monomers, and/or by chemically modifying one or more recurring units of a precursor polymer. Unless otherwise specified, a polymer or copolymer may also comprise a "terpolymer"
which generally refers to a polymer that comprises three or more different recurring units. Any one of the one or more polymers discussed herein may be used in any exemplary process, for example, as a flocculant.

[0051] In some embodiments, one or more polymers may comprise one or more monomers of the following: acryloyloxy ethyl trimethyl ammonium chloride ("AETAC");
methacryloyloxyethyltrimethylammonium chloride;
methacrylamidopropyltrimethylammonium chloride ("MAPTAC"); acrylamidopropyltrimethylammonium chloride;
methacryloyloxyethyldimethylammonium sulfate; dimethylaminoethyl acrylate;
dimethylaminopropylmethacrylamide; Q6; Q6o 4; diallyldimethylammonium chloride ("DADMAC"); calcium diacrylate ("CDA"); acrylamide; acrylic acid; any monomer substituted with a carboxylic acid group or salt thereof; 2-acrylamido-2-methylpropane sulfonic acid ("AMPS"); ethylene oxide; propylene oxide; functionalized ethylene oxide;
epoxide;
functionalized propylene oxide; epoxy or glycidyl ether functionalized hydrophobic monomers;
1 ,2-epoxy tetradecane; 2-ethylhexylglycidyl ether; 2, 2, 3, 3, 4, 4, 5, 5-octafluoropentyl ether;
benzyl glycidyl ether; 4-nonylphenyl glycidyl ether; silane- or siloxane-functionalized glycidyl ethers; silane or siloxane-functionalized monomers; 3-glycidyloxypropyl polydimethyl siloxane;
3-glycidyloxypropyl trimethoxysilane; 3-glycidoxypropyldimethylethoxysilane;
alkylene oxide;
olefin oxide; aliphatic, cycloaliphatic or mixed aliphatic/cycloaliphatic alkylene oxide; alkylene oxide substituted by one or more aromatic radicals; 1,2-epoxybutane; 2,3-epoxybutane; the epoxypentanes; the epoxyhexanes; the epoxyoctanes; the epoxydecanes; the epoxydodecanes;
2,4,4-trimethy1-1,2-epoxypentane; 2,4,4-trimethy1-2,3-epoxypentane;
cyclohexylepoxythane; 7-oxabicyclo[4.1.0]heptane; 6-oxabicyclo[3.1.0]hexane; 3-methyl-6-oxabicyclo[3.1.0]hexane; 4-ethy1-6-oxabicyclo[3.1.0]hexane; styrene oxide; 1 -phenyl- 1 ,2-epoxypropane;
1,2-butylene oxide; 2,3-butylene oxide; the epoxypentanes, the epoxyhexanes; 2,3-epoxyheptane; nonene oxide; 5-butyl-3,4-epoxyoctane; 1 ,2-epoxydodecane; 1,2-epoxyhexadecane; 1 ,2-epoxyoctadecane; 5-benzy1-2,3-epoxyheptane; 4-cyclo-hexy1-2,3-epoxypentane;
chlorostyrene oxide; styrene oxide; ortho-, meta-, and para-ethylstyrene oxide; glycidyl benzene; the oxabicycloalkanes; alkyl-substituted oxabicycloalkanes, e.g., 7-oxabicyclo[4.1.0]heptane;
oxabicyclo[3.1.0]hexane; 4-propy1-7-oxabicyclo[4.1.0]heptane; and/or 3-amy1-6-oxabicyclo[3.1.0Jhexane.]

[0052] As used herein, the term "flocculant" may generally refer to a reagent that may bridge neutralized or coagulated particles into larger agglomerates, typically resulting in more efficient settling. In some embodiments, said flocculants may comprise a polymer, copolymer, and/or terpolymer comprising one or more monomers, wherein said monomers may be one or more nonionic, one or more anionic, and/or one or more cationic monomers. In some embodiments, said flocculants may comprise one or more polymers, copolymers, and/or terpolymers comprising, but not limited to comprising, one or more monomers of the following: acryloyloxy ethyl trimethyl ammonium chloride ("AETAC");
methacryloyloxyethyltrimethylammonium chloride; methacrylamidopropyltrimethylammonium chloride ("MAPTAC");
acrylamidopropyltrimethylammonium chloride;
methacryloyloxyethyldimethylammonium sulfate; dimethylaminoethyl acrylate; dimethylaminopropylmethacrylamide; Q6;
Q6o 4;
diallyldimethylammonium chloride ("DADMAC"); calcium diacrylate ("CDA");
acrylamide;
acrylic acid; any monomer substituted with a carboxylic acid group or salt thereof; 2-acrylamido-2-methylpropane sulfonic acid ("AMPS"); ethylene oxide; propylene oxide;
functionalized ethylene oxide; epoxide; functionalized propylene oxide; epoxy or glycidyl ether functionalized hydrophobic monomers; 1 ,2-epoxy tetradecane; 2-ethylhexylglycidyl ether; 2, 2, 3, 3, 4, 4, 5, 5-octafluoropentyl ether; benzyl glycidyl ether; 4-nonylphenyl glycidyl ether;
silane- or siloxane-functionalized glycidyl ethers; silane or siloxane-functionalized monomers; 3-glycidyloxypropyl polydimethyl siloxane; 3-glycidyloxypropyl trimethoxysilane; 3-glycidoxypropyldimethylethoxysilane; alkylene oxide; olefin oxide; aliphatic, cycloaliphatic or mixed aliphatic/cycloaliphatic alkylene oxide; alkylene oxide substituted by one or more aromatic radicals; 1,2-epoxybutane; 2,3-epoxybutane; the epoxypentanes; the epoxyhexanes; the epoxyoctanes; the epoxydecanes; the epoxydodecanes; 2,4,4-trimethy1-1,2-epoxypentane; 2,4,4-trimethy1-2,3-epoxypentane; cyclohexylepoxythane; 7-oxabicyclo[4.1.0]heptane;

oxabicyclo[3.1.0]hexane; 3-methyl-6-oxabicyclo[3.1.0]hexane; 4-ethy1-6-oxabicyclo[3.1.0]hexane; styrene oxide; 1 -phenyl- 1 ,2-epoxypropane; 1,2-butylene oxide; 2,3-butylene oxide; the epoxypentanes, the epoxyhexanes; 2,3-epoxyheptane; nonene oxide; 5-butyl-3,4-epoxyoctane; 1 ,2-epoxydodecane; 1,2-epoxyhexadecane; 1 ,2-epoxyoctadecane; 5-benzy1-2,3-epoxyheptane; 4-cyclo-hexy1-2,3-epoxypentane; chlorostyrene oxide; styrene oxide; ortho-, meta-, and para-ethylstyrene oxide; glycidyl benzene; the oxabicycloalkanes;
alkyl-substituted oxabicycloalkanes, e.g., 7-oxabicyclo[4.1.0]heptane; oxabicyclo[3.1.0]hexane;
4-propy1-7-oxabicyclo[4.1.0]heptane; and/or 3-amy1-6-oxabicyclo[3.1.0Jhexane.].

[0053] As used herein, the term "produced water" generally refers to any aqueous fluids produced during any type of industrial process, e.g., an oil or gas extraction or recovery process, or any portion thereof. Typically the produced water may be obtained during an industrial process involving the use of water, generally copious amounts of water, wherein the end product of such industrial process may be an aqueous material or "produced water"
which may be of an undesirable purity. Produced water may be generated during processes or portions thereof which involve oil sands.

[0054] As used herein, the term "mechanical dewatering" generally refers to any process that may be used to aid in the dewatering of tailings, e.g., oil sands tailings. In some embodiments, mechanical dewatering may comprise centrifugation, thin lift, and/or thickeners. In some embodiments, mechanical dewatering may comprise centrifugation.

[0055] As used herein, the term "introduction" generally refers to any means known in the art by which addition of a substance, e.g., a polymer, e.g., carbon dioxide, may occur.

[0056] As used herein, the terms "polymer introduction", "introduction of a polymer", and "introduction of one or more polymers" generally refer to one or more introductions of one or more polymers, e.g., one or more flocculants, to a stream. Introductions of polymers may occur one or more times at one or more time-points and one or more locations during methods of treating tailings. Introductions of polymers may occur by any means known in the art that is appropriate for a given polymer and/or for any form of a given polymer, e.g., dry, or, in solution.
The introduction of one or more polymers according to the invention may also include the addition or introduction of one or more monomers, e.g., into a stream, which after introduction polymerize to form one or more polymers . The one or more monomers and/or one or more polymers may be introduced by any means suitable means, e.g., via one or more injections, pouring, and/or dripping, for a given monomer and/or polymer, and furthermore any means suitable for any form of a given polymer, e.g., dry, or, in solution.
METHODS

[0057] Disclosed herein are methods for treating tailings such as oil sands tailings. In exemplary embodiments, the methods involve methods for flocculating solids in the tailings and/or methods for the dewatering of tailings. Exemplary methods may generally comprise the use of one or more flocculants in order to flocculate solids from the tailings, in combination with adjusting the pH of a solution comprising said tailings. In exemplary embodiments, the pH
adjustment is performed not before a first introduction of one or more polymers and not after completion of dewatering. The exemplary methods generally may be used for treating oil sands tailings in need of solid-liquid separation, e.g., in order to efficiently recycle water and to reduce the volume of tailings which may be transferred to a dedicated disposal area and/or a tailings pond. By using the exemplary methods, a more complete separation of the solids from the water may be achieved, improving process efficiency relative to conventional processes for treating tailings streams. The exemplary methods described herein may be used to enhance settling of solids, especially fine and ultrafine solids and/or MFT, in tailings and particularly in oils sands and/or oil sands ore tailings streams. The exemplary methods may be readily incorporated into current processing facilities and may provide economic and environmental benefits.
Additionally, the present disclosure generally relates to any product that may be produced by any of the methods described herein.

[0058] In some embodiments, the pH adjustment of a solution comprising said tailings may be effected by introduction of carbon dioxide. In some embodiments, the pH
adjustment of a solution comprising said tailings may be effected by introduction of an acid and/or highly acidic dispersant, coagulant, flocculant, and/or any other process additive product.
In some embodiments, said method may comprise the introduction of one or more polymers by any suitable means such as via injection, pouring, dripping, and the like. In some embodiments, said one or more polymers may comprise one or more flocculants. In some embodiments, said method may comprise introduction of several different flocculants. In some embodiments, said flocculants may comprise a polymer comprising one or more monomers of the following:
acryloyloxy ethyl trimethyl ammonium chloride ("AETAC");
methacryloyloxyethyltrimethylammonium chloride;
methacrylamidopropyltrimethylammonium chloride ("MAPTAC"); aerylamidopropyltrimethylammonium chloride;
methaeryloyloxyethyldimethylammonium sulfate; dimethylaminoethyl acrylate;
dimethylaminopropylmethacrylamide; Q6; Q6o 4; diallyldimethylammonium chloride ("DADMAC"); calcium diacrylate ("CDA"); acrylamide; acrylic acid; any monomer substituted with a carboxylic acid group or salt thereof; 2-acrylamido-2-methylpropane sulfonic acid ("AMPS"); ethylene oxide; propylene oxide; functionalized ethylene oxide;
epoxide;
functionalized propylene oxide; epoxy or glycidyl ether functionalized hydrophobic monomers;
1 ,2-epoxy tetradecane; 2-ethylhexylglycidyl ether; 2, 2, 3, 3, 4, 4, 5, 5-octafluoropentyl ether;
benzyl glycidyl ether; 4-nonylphenyl glycidyl ether; silane- or siloxane-functionalized glycidyl ethers; silane or siloxane-functionalized monomers; 3-glycidyloxypropyl polydimethyl siloxane;
3-glycidyloxypropyl trimethoxysilane; 3-glycidoxypropyldimethylethoxysilane;
alkylene oxide;
olefin oxide; aliphatic, cycloaliphatic or mixed aliphatic/cycloaliphatic alkylene oxide; alkylene oxide substituted by one or more aromatic radicals; 1,2-epoxybutane; 2,3-epoxybutane; the epoxypentanes; the epoxyhexanes; the epoxyoctanes; the epoxydecanes; the epoxydodecanes;
2,4,4-trimethy1-1,2-epoxypentane; 2,4,4-trimethy1-2,3-epoxypentane;
cyclohexylepoxythane; 7-oxabicyclo[4.1.0]heptane; 6-oxabicyclo[3.1.0]hexane; 3-methy1-6-oxabicyclo[3.1.0]hexane; 4-ethy1-6-oxabicyclo[3.1.0]hexane; styrene oxide; 1 -phenyl- 1 ,2-epoxypropane;
1,2-butylene oxide; 2,3-butylene oxide; the epoxypentanes, the epoxyhexanes; 2,3-epoxyheptane; nonene oxide; 5-butyl-3,4-epoxyoctane; 1 ,2-epoxydodecane; 1,2-epoxyhexadecane; 1 ,2-epoxyoctadecane; 5-benzy1-2,3-epoxyheptane; 4-cyclo-hexy1-2,3-epoxypentane;
chlorostyrene oxide; styrene oxide; ortho-, meta-, and para-ethylstyrene oxide; glycidyl benzene; the oxabicycloalkanes; alkyl-substituted oxabicycloalkanes, e.g., 7-oxabicyclo[4.1.0]heptane;
oxabicyclo[3.1.0]hexane; 4-propy1-7-oxabicyclo[4.1.0]heptane; and/or 3-amy1-6-oxabicyclo[3.1.0Jhexane.]. In some embodiments, said method may comprise use of one or more flocculants, wherein said one or more flocculants may be any flocculant that may achieve a desired result when used in conjunction with the methods described herein.

[0059] In some embodiments, said method may comprise a plurality of introductions of one or more polymers. For example, said method may comprise introduction of a first polymer, a pH
adjustment, and then introduction of a second polymer. In some embodiments, said method may comprise introduction of a first polymer, introduction of a second polymer, and then a pH
adjustment. In some embodiments, said first and second polymers may comprise different polymers. In some embodiments, said first and second polymers may comprise the same polymer. In some embodiments, said method may comprise a plurality of introductions of one or more polymers, wherein each introduction of said plurality of introductions may occur at different time points in said method. In some embodiments, said method may comprise a plurality of introductions of one or more polymers, wherein each introduction of said plurality of introductions may occur at the same time point in said method. In some embodiments, the pH
adjustment may occur more than one time during the treatment of said tailings, e.g., the pH of a solution comprising tailings may be adjusted during a first introduction of a first polymer, which . =
may be followed by introduction of a second polymer, and then subsequently the pH of the solution may be adjusted again.

[0060] In some embodiments, the pH of said tailings before said pH adjustment may be about 6.60 or higher. In some embodiments, the pH of said tailings before said pH
adjustment may be about 6.60 or higher, 6.70 or higher, 6.80 or higher, 6.90 or higher, 7.00 or higher, 7.10 or higher, 7.20 or higher, 7.30 or higher, 7.40 or higher, 7.50 or higher, 7.60 or higher, 7.70 or higher, 7.80 or higher, 7.90 or higher, 8.00 or higher, 8.10 or higher, 8.20 or higher, 8.30 or higher, 8.40 or higher, 8.50 or higher, 8.60 or higher, 8.70 or higher, 8.80 or higher, 8.90 or higher, 9.00 or higher, 9.10 or higher, 9.20 or higher, 9.30 or higher, 9.40 or higher, 9.50 or higher, 9.60 or higher, 9.70 or higher, 9.80 or higher, 9.90 or higher, or 10.00 or higher.

[0061] In some embodiments, the pH of said tailings after said pH adjustment may be about 6.50 or lower. In some embodiments, the pH of said tailings after said pH
adjustment may be about 6.50 or lower, 6.40 or lower, 6.30 or lower, 6.20 or lower, 6.10 or lower, 6.00 or lower, 5.90 or lower, 5.80 or lower, 5.70 or lower, 5.60 or lower, 5.50 or lower, 5.40 or lower, 5.30 or lower, 5.20 or lower, 5.10 or lower, 5.00 or lower, 4.90 or lower, 4.80 or lower, 4.70 or lower, 4.60 or lower, 4.50 or lower, 4.40 or lower, 4.30 or lower, 4.20 or lower, 4.10 or lower, or 4.00 or lower.

[0062] In some embodiments, said method may comprise the following steps: a. a first introduction of one or more polymers; b. flocculation; c. floc conditioning;
d. mechanical dewatering; e. solid liquid (cake-centrate) separation; and f. cake deposition for continued cake drying and/or dewatering. In some embodiments, said method may comprise the following steps:
a. a first introduction of one or more polymers; b. flocculation; c. floc conditioning; d.
mechanical dewatering; e. solid liquid (cake-centrate) separation; and f. cake deposition for continued cake drying and/or dewatering; under conditions wherein said one or more polymers are allowed to mix or interact with the tailings prior to any pH adjustment, i.e., said one or more polymers are permitted to interact with any solids that may be present in said tailings before a pH
adjustment is effected. This initial mixing of the polymer or polymers with the solids in the tailings may be effected for any desired duration, e.g., for several minutes, hours or longer. In some embodiments, a plurality of introductions of one or more polymers may occur during a method that may comprise steps a.-f. In some embodiments, the pH adjustment may occur more than one time during a method that comprises steps a.-f. In some embodiments, the pH may be adjusted not before step a. and not after step d. In some embodiments, the pH
adjustment may occur during and/or after a polymer introduction. In some embodiments, the pH
adjustment may occur before, during, and/or after flocculation. In some embodiments, the pH
adjustment may occur before, during, and/or after floc conditioning. In some embodiments, the pH adjustment may occur before or during mechanical dewatering, e.g., centrifugation, thin lift, and/or the introduction of one or more thickeners.

[0063] In some embodiments, said method may comprise introduction of one or more flocculants, e.g., the introduction of cationic, neutral or anionic flocculants, and/or a combination thereof In some embodiments, said flocculants may comprise one or more polymers comprising one or more monomers of the following: acryloyloxy ethyl trimethyl ammonium chloride ("AETAC"); methacryloyloxyethyltrimethylammonium chloride;
methacrylamidopropyltrimethylammonium chloride ("MAPTAC");
acrylamidopropyltrimethylammonium chloride;
methacryloyloxyethyldimethylammonium sulfate; dimethylaminoethyl acrylate; dimethylaminopropylmethacrylamide; Q6;
Q6o 4;
diallyldimethylammonium chloride ("DADMAC"); calcium diacrylate ("CDA");
acrylamide;
acrylic acid; any monomer substituted with a carboxylic acid group or salt thereof 2-acrylamido-2-methylpropane sulfonic acid ("AMPS"); ethylene oxide; propylene oxide;
functionalized ethylene oxide; epoxide; functionalized propylene oxide; epoxy or glycidyl ether functionalized hydrophobic monomers; 1 ,2-epoxy tetradecane; 2-ethylhexylglycidyl ether; 2, 2, 3, 3, 4, 4, 5, 5-octafluoropentyl ether; benzyl glycidyl ether; 4-nonylphenyl glycidyl ether;
silane- or siloxane-functionalized glycidyl ethers; silane or siloxane-functionalized monomers; 3-glycidyloxypropyl polydimethyl siloxane; 3-glycidyloxypropyl trimethoxysilane; 3-glycidoxypropyldimethylethoxysilane; alkylene oxide; olefin oxide; aliphatic, cycloaliphatic or mixed aliphatic/cycloaliphatic alkylene oxide; alkylene oxide substituted by one or more aromatic radicals; 1,2-epoxybutane; 2,3-epoxybutane; the epoxypentanes; the epoxyhexanes; the epoxyoctanes; the epoxydecanes; the epoxydodecanes; 2,4,4-trimethy1-1,2-epoxypentane; 2,4,4-trimethy1-2,3-epoxypentane; cyclohexylepoxythane; 7-oxabicyclo[4.1.0]heptane;

oxabicyclo[3.1.0]hexane; 3-methyl-6-oxabicyclo[3.1.0]hexane; 4-ethy1-6-oxabicyclo[3.1.0]hexane; styrene oxide; 1 -phenyl- 1 ,2-epoxypropane; 1,2-butylene oxide; 2,3-butylene oxide; the epoxypentanes, the epoxyhexanes; 2,3-epoxyheptane; nonene oxide; 5-butyl-3,4-epoxyoctane; 1 ,2-epoxydodecane; 1,2-epoxyhexadecane; 1 ,2-epoxyoctadecane; 5-benzy1-2,3-epoxyheptane; 4-cyclo-hexy1-2,3-epoxypentane; chlorostyrene oxide; styrene oxide; ortho-, meta-, and para-ethylstyrene oxide; glycidyl benzene; the oxabicycloalkanes;
alkyl-substituted oxabicycloalkanes, e.g., 7-oxabicyclo[4.1.0]heptane; oxabicyclo[3.1.0]hexane;
4-propy1-7-oxabicyclo[4.1.0]heptane; and/or 3-amyl-6-oxabicyclo[3.1.0Jhexaned.

[0064] In some embodiments, said tailings may comprise oil sands tailings;
mature fine tailings;
fluid fine tailings; tailings from coal mining, copper mining, aluminum mining, nickel mining, gold mining, and/or mineral processing; and/or in-process tailings. In some embodiments, said tailings may comprise oil sands tailings. In some embodiments, said tailings may comprise mature fine tailings.

[0065] In some embodiments, said method may comprise a mechanical dewatering step. Said mechanical dewatering step may comprise centrifugation, thin lift, and/or the introduction of one or more thickeners.

[0066] In some embodiments, the pH of said tailings may not be adjusted prior to a first introduction of one or more polymers, e.g., one or more flocculants. In other embodiments the pH of said tailings or a portion thereof may have been previously adjusted (higher or lower) prior to a first introduction of one or more polymers, e.g., one or more flocculants. In some embodiments, the pH of said tailings prior to a first introduction of one or more polymers, e.g., via injection may be or may be adjusted to between about 7.0 to about 10.0, wherein said adjustment may occur by any means known in the art.

[0067] In some embodiments, said method may result in a centrate solids content of 1.00% or less, 0.95% or less, 0.90% or less, 0.85% or less, 0.80% or less, 0.75% or less, 0.70% or less, 0.65% or less, 0.60% or less, 0.55% or less, 0.50% or less, 0.45% or less, 0.40% or less, 0.35%
or less, 0.30% or less, 0.25% or less, 0.20% or less, 0.15% or less, or 0.10%
or less that results from treating said tailings in accordance with said method. In some embodiments, said method may comprise a cake solids content of 40.0% or more, 40.5% or more, 41.0% or more, 41.5% or more, 42.0% or more, 42.5% or more, 43.0% or more, 43.5% or more, 44.0% or more, 44.5% or more, 45.0% or more, 45.5% or more, 46.0% or more, 46.5% or more, 47.0% or more, 47.5% or more, or 48.0% or more, 48.5% or more, 49.0% or more, 49.5% or more, 50.0% or more, 50.5%
or more, 51.0% or more, 51.5% or more, 52.0% or more, 52.5% or more, 53.0% or more, 53.5%
or more, 54.0% or more, 54.5% or more, 55.0% or more, 55.5% or more, 56.0% or more, 56.5%
or more, 57.0% or more, 57.5% or more, 58.0% or more, 58.5% or more, 59.0% or more, 59.5%
or more, 60.0% or more, 60.5% or more, 61.0% or more, 61.5% or more, 62.0% or more, 62.5%

or more, 63.0% or more, 63.5% or more, 64.0% or more, 64.5% or more, or 65.0%
or more that results from treating said tailings.

[0068] In some embodiments, said method may comprise introduction of a polymer comprising acrylamide monomers. In some embodiments, said method may comprise introduction of a copolymer comprising acrylamide monomers and acrylic acid monomers. In some embodiments, said method may comprise introduction of a polymer comprising acrylic acid monomers. In some embodiments, said acrylic acid monomers may comprise a monomer percentage of 10% or more, 15% or more, 20% or more, 25% or more, 30% or more, 35% or more, 40% or more, 45%
or more, 50% or more, 60% or more, 70% or more, 80% or more, or 90% or more, 95% or more, 99% or more. In some embodiments, said acrylic acid monomers may comprise a monomer percentage of 100%.

[0069] In some embodiments, said method may comprise introduction of a polymer solution comprising a pH of 3.50 or higher, 4.00 or higher, 4.50 or higher, 5.00 or higher, 5.50 or higher, 6.00 or higher, 6.50 or higher, or 7.00 or higher. In some embodiments, said method may comprise introduction of a polymer at any concentration necessary to achieve a desired result in accordance with said method. In some embodiments, said method may comprise introduction of a polymer at a concentration of 1 ppm or less, 10 ppm or less, 25 ppm or less, 50 ppm or less, 50 ppm or more, 100 ppm or more, 200 ppm or more, 300 ppm or more, 400 ppm or more, 500 ppm or more, 600 ppm or more, 700 ppm or more, 800 ppm or more, 900 ppm or more, 1000 ppm or more, 1100 ppm or more, 1200 ppm or more, 1300 ppm or more, 1400 ppm or more, 1500 ppm or more, 1600 ppm or more, 1700 ppm or more, 1800 ppm or more, 1900 ppm or more, or 2000 ppm or more. In some embodiments, the dosage of a polymer may comprise a dosage that may be adjusted based on the molecular weight of the polymer.

[0070] In some embodiments, said method may comprise introduction of a polymer comprising any standard viscosity value. In some embodiments, said one or more polymers and/or said one or more flocculants may begin to mix with said tailings before said pH
adjustment occurs. In some embodiments, said method may comprise introduction of a polymer in a dry form, e.g., a DPAM, and/or a polymer in a solution form, e.g., an SPAM.

[0071] The following examples are presented for illustrative purposes only and are not intended to be limiting.

EXAMPLES
Materials and Methods

[0072] MFT was acquired from an active oil sands mining site in Canada. The MFT sample comprised a solid content that was mostly clay and bitumen with little to no sand present. The MFT had a pH of about 7.8 and a total solid content of 24.4% (bitumen 1.16%) with a mean particle size of 11.8 um. Process water was acquired from an active oil sands mining site in Canada. The pH of said process water (7.9) was similar to that of the MFT.
This process water was used to prepare the polymer solutions described in Table 1 and the examples that follow.
Table 1 ¨ Composition of Polymers Polymer General Charge (')/0 Form of Molecular SV
Number Type of Acrylic Acid Polymer wt. (cP) Polymer Monomers) 1 DPAM 27 Na n/a 4.10 2 DPAM 27 Na n/a 3.08 3 DPAM 27 Na n/a 1.66 4 SPAM 28 Acid >1 MDa*
SPAM 28 Acid 502 kDa ¨1*
6 DPAM 100 Acid n/a n/a 7** DPAM 100 Na** n/a n/a 8 SPAM 100 Acid 361 kDa ¨1*
* Estimated, ** 7 is polymer 6 neutralized with NaOH during dissolution resulting in a pH of 6.93 at 0.813%.

[0073] Dry polyacrylamide ("DPAM") polymer solutions were prepared by slowly adding the dry polymer to process water with stirring by overhead stirrer fitted with a Phipps-Bird paddle.
Polymer 3 was not dried due to low gel strength. Therefore, the polymer solution was prepared directly from the gel by adding the gel to process water and inverting until dissolved. Solution polyacrylamide ("SPAM") polymers were diluted with process water in a bottle and mixed by shaking to afford the polymer solution.

[0074] In general, treatment of solutions comprising MFT as described by the present examples proceeded as follows. For the flocculation of the MFT, 500 g of MFT was added to a 1 L beaker.
A 4-blade pitched impeller (Shell design) attached to a Eurostar 60 overhead mixer was set 20 mm from the bottom of the beaker. The motor was set to 300 rpm and the torque readout of the Eurostar was zeroed. The FBRM probe was set in the beaker at a position which allowed the probe to stay submerged in the mixing MFT without contacting the impeller. An initial mixing period was employed to condition the MFT, adjust the pH, and achieve a constant particle size.
The polymer solution was injected as fast as possible to the vortex of the MFT
(time = 0). A
second pH adjustment was made by a single injection 60 s after polymer addition (time = 60 s).
The solution was mixed for a total time of 131 s after polymer addition.

[0075] The flocculated MFT was transferred to two 50 mL centrifuge tubes using a modified plastic pipet with the narrow portion of the pipet tip cut off to prevent the flocculated material from being subjected to additional shear during transfer. The tubes were placed in a centrifuge for 2 min at a speed of 910 rcf. The resulting centrate from both tubes were combined in a beaker and homogenized. A portion of the centrate was weighed into a tared aluminum pan and placed in an oven overnight at 105-110 C to determine centrate solids content. Excess centrate was removed from the walls of the centrifuge tube by wiping with a laboratory tissue. A whole centrifuge cake was transferred into a tared aluminum pan with a spatula, weighed, and placed in an oven overnight at 105-110 C to determine cake solids content.
Example 1: Polymer Performance under Various pH Conditions

[0076] In the present example, the cake and centrate solids content percentages were evaluated at various initial and final pH conditions with Polymer 2 acting as a flocculant during tailings treatment (see Table 2). The effect of pH adjustment on the performance of Polymer 2 was assessed (see Table 2).
TABLE 2¨ POLYMER 2 PERFORMANCE UNDER VARIOUS INITIAL AND FINAL PH
CONDITIONS
Exp. Polymer 1" Additive 2" Additive pH Solids Content OM
(1E) ( 1.) ID Conc. Dose NaOH HCl NaOH HCl Initial Final Centrate Cake (ppm) 6M 12M 6M 12 M
A 2 0.800% 1000 0 0 0 0 7.7 7.86 1.50% 41.2%
2 0.800% 1000 0 0 1000 0 7.8 10.2 2 0.800% 1000 0 0 0 500 7.9 5.50 0.19% 44.6%
D 2 0.800% 1000 0 500 0 0 5.9 5.90 5.36% 41.0%

=

[0077] Increasing the pH to 10.2 after polymer addition resulted in a stable mixture that did not separate upon centrifugation (see Table 2, Experiment B). Reduction of the pH
to 5.50 following addition of Polymer 2 improved performance, as centrate solids were reduced and centrifuge cake solids demonstrated an improvement (see Table 2, Experiment C). Acid addition before polymer addition (see Table 2, Experiment D) was not as effective as adding the acid after the polymer (see Table 2, Experiment C). Reducing the pH before polymer addition (see Table 2, Experiment D) appeared to decrease performance from the baseline (see Table 2, Experiment A, where the pH was not adjusted).

[0078] Further experiments evaluating the performance of Polymer 2 at various pH conditions were performed and evaluated (see Table 3). For the experiments of Table 3, the initial pH of the solutions was approximately the same, whereas the final pH was adjusted to different values for assessment of performance.
TABLE 3- FINAL PH VS. CAKE AND CENTRATE SOLIDS CONTENT
Exp. Polymer 1St Additive (4) 2" Additive pH
Solids Content (')/0) (IL) ID Conc. Dose NaOH HCl NaOH HCI Initi Final Centrate Cake (ppm 6M 12M 6M 12M at A 2 0.800% 1000 0 0 0 0 7.7 7.86 1.50% 41.2%
E 2 0.800% 1000 0 0 0 125 7.7 7.04 1.18% 41.5%
F 2 0.800% 1000 0 0 0 250 7.6 6.43 0.80% 41.0%
G 2 0.800% 1000 0 0 0 375 7.5 5.93 0.32% 41.3%
H 2 0.800% 1000 0 0 0 450 7.8 5.69 0.21% 43.7%
C 2 0.800% 1000 0 0 0 500 7.9 5.50 0.19% 44.6%
I 2 0.800% 1000 0 0 0 500 7.7 5.48 0.20% 43.1%
J 2 0.800% 1000 0 0 0 600 7.7 5.08 0.23% 43.0%
K 2 0.800% 1000 0 0 0 750 7.6 4.60 0.22% 43.9%
L 2 0.800% 1000 0 0 0 1000 7.5 3.76 0.29% 42.9%

[0079] Figure 1 presents a plot of cake and centrate solids vs. final pH from the data presented in Table 3. All pH adjustments were made by adding various amounts of acid after polymer addition. As presented in Table 3 and Figure 1, the centrate solids reduced sharply as the final pH was reduced from about 7.80 to about 5.70. At pH of about 5.70, the centrate contained almost no solid particles, and the measured centrate solid content was almost entirely dissolved solids (see Table 3 and Figure 1). Further pH reduction from about 5.70 to about 4.50 resulted in consistently low centrate solids.
Example 2: Polymer Performance at Various Concentrations

[0080] In the present example, polymer performance was evaluated at various concentrations wherein the initial pH was approximately the same between different experiments, and further wherein the final pH was either about 4.50 (see Table 4 and Figure 2) or about 5.40 (see Table 4 and Figure 3). The data presented in Figure 2 and Figure 3 as well as Table 4 demonstrated that centrate solids increased sharply below a minimum polymer dose of 900 ppm.
Equal to or above 900 ppm, centrate solids were low and were approximately the same over the dose range assessed (up to 2,000 ppm). Centrate performance was the same for both the final pH conditions of about 4.50 (Figure 2) and about 5.40 (Figure 3).
TABLE 4- POLYMER 2 PERFORMANCE AT VARIOUS DOSES AT FINAL PH OF 4.5 OR
5.4 Exp. Polymer 1' Additive ( L) 2" Additive pH
Solids Content (`)/0) ( L) ID Conc. Dose NaOH HCl NaOH HC1 Initi Final Centrate Cake (ppm 6M 12M 6M 12M al M 2 0.800% 800 0 0 0 750 7.33 4.41 0.99% 39.3%
N 2 0.800% 900 0 0 0 750 7.56 4.47 0.23% 41.7%
K 2 0.800% 1000 0 0 0 750 7.6 4.60 0.22% 43.9%
O 2 0.800% 1200 0 0 0 750 7.71 4.45 0.23% 47.2%
P 2 0.800% 1500 0 0 0 750 7.43 4.43 0.24% 48.2%
Q 2 0.800% 2000 0 0 0 750 7.80 4.44 0.20% 47.5%
R 2 0.813% 800 0 0 0 500 7.79 5.46 0.92% 40.6%
S 2 0.813% 900 0 0 0 500 7.63 5.38 0.33% 41.0%
T 2 0.813% 1000 0 0 0 500 7.87 5.42 0.20% 45.2%
U 2 0.813% 1200 0 0 0 500 7.87 5.41 0.19% 47.7%
/ 2 0.813% 1500 0 0 0 500 7.75 5.39 0.18% 47.7%
W 2 0.813% 2000 0 0 0 500 7.87 5.80 0.19% 45.3%

[0081] Cake solids increased as polymer dose increased from 900 ppm to its maximum at 1200 ppm for both final pH conditions (see Figure 2, Figure 3, and Table 4). The maximum cake solids achieved was about 48% at both pH 4.50 as well as 5.40. The results of Example 2 demonstrated that a wide range of doses of polymer and final pH may be used to achieve maximum performance.
Example 3: Polymer Performance at Various Initial pH Conditions

[0082] In the following example, polymer performance was evaluated at various initial pH
conditions (before polymer addition), wherein the final pH value was adjusted to approximately the same value after polymer addition for all of said experiments (see experiments X-AD in Table 5). The resulting centrifuge cake performance was evaluated (see Figure 4 and Table 5).

FINAL PH
Exp. Polymer Pt Additive ( 1) 2" Additive PH
Solids Content CYO
(p,L) ID Conc. Dose NaOH HCl NaOH HC1 Initi Final Centrate Cake (ppm 6M 12M 6M 12M at X 2 0.813% 1600 500 0 0 750 9.47 5.97 0.25% 47.1%
Y 2 0.813% 1600 250 0 0 625 8.65 5.48 0.21% 48.2%
Z 2 0.813% 1600 125 0 0 563 8.23 5.45 0.19% 48.2%
AA 2 0.813% 1600 0 0 0 500 7.77 5.41 0.19% 48.1%
AB 2 0.813% 1600 0 63 0 438 7.34 5.47 0.18% 47.2%
AC 2 0.813% 1600 0 125 0 375 6.94 5.38 0.19% 44.5%
AD 2 0.813% 1600 0 250 0 250 6.26 5.46 0.20% 39.2%

[0083] The data presented in Figure 4 and Table 5 demonstrated effective performance over a wide initial pH range (for example see Experiment X and Experiment AC in Table 5), with high performance that appeared to occur at an initial pH of about 7.60 to 8.60.
Example 4: Performance of Polymers under Various Conditions

[0084] In the present example, three additional polymers, Polymers 1, 4, and 5, which had different molecular weights but similar charges, were assessed for performance under various conditions (see Table 6). Figure 5 and Figure 6 present plots for experiments that were performed with Polymer 1 and Polymer 4. The maximum cake solids for Polymer 1 and Polymer 4 were about 45% and 46%. The critical minimum dose for centrate performance for Polymer 1 and Polymer 4 was about 800 ppm for Polymer 1 and about 1200 ppm for Polymer 4.

TABLE 6 - PERFORMANCE OF POLYMERS 1,4, AND 5 AT VARIOUS DOSES AND AT
CONSTANT FINAL PH
Exp. Polymer 1st Additive (IL) 2" Additive pH
Solids Content (%) (pL) ID Conc. Dose NaOH HC1 NaOH HCl Initi Final Centrate Cake (ppm 6M 12M 6M 12M al AE 1 0.813% 700 0 0 0 750 7.76 4.48 0.45% 39.6%
AF 1 0.813% 800 0 0 0 750 7.81 4.48 0.24% 40.8%
AG 1 0.813% 1000 0 0 0 750 7.80 4.48 0.23% 44.0%
All 1 0.813% 1500 0 0 0 750 7.79 4.59 0.23% 44.7%
Al 1 0.813% 2000 0 0 0 750 7.71 4.59 0.21% 44.0%
AJ 4 3.05% 1000 0 0 0 750 7.80 4.41 3.74% 39.1%
AK 4 3.05% 1100 0 0 0 750 7.62 4.35 2.63% 39.7%
AL 4 3.05% 1200 0 0 0 750 7.86 4.31 0.28% 45.1%
AM 4 3.05% 1500 0 0 0 750 7.54 4.28 0.25% 45.9%
AN 4 3.05% 2000 0 0 0 750 7.47 4.34 0.26% 45.7%
AO 5 3.05% 1000 0 0 0 750 7.49 4.24 10.9% 39.1%
AP 5 3.05% 1250 0 0 0 750 7.41 4.27 8.32% 39.4%
AQ 5 3.05% 1400 0 0 0 750 7.86 4.42 0.29% 44.4%
AR 5 3.05% 1500 0 0 0 750 7.41 4.21 0.31% 42.8%
AS 5 3.05% 2000 0 0 0 750 7.75 4.24 0.31% 45.6%
AT 5 3.05% 4000 0 0 0 750 7.67 4.34 0.25% 44.2%

[0085] Figure 7 presents data related to experiments performed using Polymer 5, which was a low molecular weight polymer. The maximum cake solids were about 46% at 2000 ppm with a critical minimum dose for centrate performance of about 1400 ppm for Polymer 5.
Example 5: Polymer Performance under Various Conditions

[0086] In the following example, the performance of Polymer 3 was evaluated under various conditions. For Polymer 3 the maximum cake solids were assessed by a series of experiments AU-BE (see Table 7) varying both the dose and final pH. The critical minimum dose for centrate performance was not determined, but should be equal to the minimum dose tested (1000 ppm) or less. The maximum cake solids achieved at a final pH of about 4.5 was 47% (see Figure 8).

VALUES
Exp. Polymer 1st Additive (pL) 2"d Additive pH
Solids Content ("A) ( L) ID Conc. Dose NaOH HCl NaOH HC1 Initi Final Centrate Cake (ppm 6M 12M 6M 12M at AU 3 0.800% 1000 0 0 0 750 7.89 4.48 0.29% 46.6%
AV 3 0.800% 1508 0 0 0 750 7.86 4.51 0.28% 46.9%
AW 3 0.800% 1967 0 0 0 750 7.91 4.60 0.27% 47.0%
AX 3 0.800% 1000 0 0 0 500 7.94 5.45 0.21% 46.5%
AY 3 0.800% 1508 0 0 0 500 7.91 5.46 0.19% 46.9%
AZ 3 0.800% 1508 0 0 0 500 7.83 5.45 0.20% 46.7%
BA 3 0.800% 1508 0 0 0 500 7.87 5.49 0.19% 46.8%
BB 3 0.800% 1967 0 0 0 500 7.92 5.54 0.23% 45.9%
BC 3 0.800% 1000 0 0 0 0 7.86 7.97 0.86% 43.0%
BD 3 0.800% 1508 0 0 0 0 7.90 7.94 1.34% 41.6%
BE 3 0.800% 1967 0 0 0 0 7.90 7.96 1.64% 40.2%

[0087] A contour plot is shown in Figure 9 to demonstrate the relationship of performance with dose and final pH for Polymer 3. Without the pH adjustment, i.e., where the final pH remains near 7.8, cake solids were low and very responsive to changes in dose and pH
(see Figure 9). In the range of final pH values of about 4.5 to about 5.4, there was a plateau of maximum cake solids (see Figure 9). In this range, performance was high and unresponsive to changes in dose and final pH.
Example 6: Performance of Polymers

[0088] Polymers 1-5 had similar charge but differed by molecular weight (see Table 1). The maximum cake solids and minimum critical dose for centrate solids (as determined above) are shown in Table 8. The results indicated that highest cake solids may be achieved with an intermediate molecular weight polymer.

CENTRATE SOLIDS
Polymer ID Maximum Exp. ID Dose Critical Polymer SV Cake Solids (ppm) mimimum (cps) dose (ppm) 1 4.10 44.7% AH 1500 800 2 3.08 48.2% P 1500 900 3 1.66 46.7% AY, AZ, BA 1508 <1000 4 ¨1.2-1.4* 45.9% AM 1500 1200 ¨1 n/a n/a n/a 1400

[0089] Maximum cake solids vs. polymer molecular weight as standard viscosity is plotted in Figure 10. The plot indicates the highest, maximum cake solids content is about 48.5% for a polymer having a standard viscosity of about 2.5.
Example 7: Performance of Polymers under Various Conditions

[0090] In contrast to Polymers 1-5, which had 27-28% acrylic acid monomer (or charge) content, Polymers 7-8 were polyacrylic acid homopolymers, having 100% acrylic acid monomer content. Polymer 6 was prepared in the acid form. Since no NaOH was used to neutralize the acrylic acid monomer, Polymer 6 contained no sodium acrylate groups or sodium content.
Polymer 7 was a solution of polymer 6 dissolved in process water with caustic resulting in a 0.813% polymer solution at a pH of 7Ø

[0091] Figure 11 and Figure 12 present plots of dose vs. solids for Polymers 6 and 7, respectively, and the results are also presented in Table 9. Both polymers resulted in the same minimum critical dose for centrate performance of about 1300 ppm. Cake solids for Polymer 6 increased from 38% to a maximum 45% as dose increased from 1300 to 2000 ppm.
The cake solids for Polymer 7 increased from 38% to a maximum 45% over dose range of 1300 to 1500 ppm and achieved 45.5% cake solids at 2000 ppm.

TABLE 9- PERFORMANCE OF POLYMERS 6,7, AND 8 AT VARIOUS DOSES AND A
CONSTANT FINAL PH
Exp. Polymer 1st Additive ( L) 2" Additive pH
Solids Content ( /0) ( L) ID Conc. Dose NaOH HCI NaOH HC1 Initi Final Centrate Cake (ppm 6M 12M 6M 12M al BF 6 0.813% 1000 0 0 0 750 7.60 4.28 2.73% 37.4%
BG 6 0.813% 1200 0 0 0 750 7.92 4.13 0.37% 37.2%
BH 6 0.813% 1300 0 0 0 750 7.87 4.17 0.24% 38.0%
BI 6 0.813% 1500 0 0 0 750 7.82 4.14 0.24% 40.0%
BJ 6 0.813% 2000 0 0 0 750 7.61 3.88 0.23% 44.9%
BK 7 0.813% 1000 0 0 0 750 7.79 4.47 3.51% 38.1%
BL 7 0.813% 1200 0 0 0 750 7.82 4.56 0.54% 37.9%
BM 7 0.813% 1300 0 0 0 750 7.80 4.41 0.24% 40.8%
BN 7 0.813% 1500 0 0 0 750 7.85 4.32 0.24% 44.7%
BO 7 0.813% 2000 0 0 0 750 7.74 4.65 0.22% 45.7%
BP 8 3.05% 800 0 0 0 750 7.55 4.22 2.00% 39.1%
BQ 8 3.05% 900 0 0 0 750 7.66 4.26 0.28% 40.7%
BR 8 3.05% 1000 0 0 0 750 7.40 4.21 0.28% 41.4%
BS 8 3.05% 1250 0 0 0 750 7.76 4.17 0.31% 42.0%
BT 8 3.05% 1500 0 0 0 750 7.45 4.13 0.29% 41.6%
BU 8 3.05% 2000 0 0 0 750 7.43 4.10 0.27% 39.9%

[0092] A low molecular weight (361 kDa) polymer, Polymer 8, was assessed.
Figure 13 presents the plot of dose vs. solids for Polymer 8. The minimum critical dose for centrate performance for Polymer 8 was about 900 ppm. The cake solids reached a maximum of about 42% for Polymer 8.

[0093] In the preceding procedures, various steps have been described. It will, however, be evident that various modifications and changes may be made thereto, and additional procedures may be implemented, without departing from the broader scope of the exemplary procedures as set forth in the claims that follow.

Claims (49)

1. A method of treating tailings which method includes the use of one or more flocculants in order to improve flocculant performance, wherein said method comprises a first pH
adjustment of a solution comprising said tailings, wherein said first pH
adjustment occurs not before a first introduction of one or more polymers and not after completion of mechanical dewatering.

2. The method claim 1, wherein additional polymers are added after said first pH
adjustment.

3. The method claim 1 or 2, which may include one or more other pH
adjustments of the solution comprising the tailings, which other pH adjustment or adjustments are effected before or after the first pH adjustment.

4. The method claim 1, 2 or 3 wherein said pH adjustment is effected by the introduction of carbon dioxide.

5. The method of any one of the foregoing claims, wherein said pH
adjustment is effected by introducing an acid and/or highly acidic dispersant, coagulant, flocculant, or any other process additive product.

6. The method of any one of the foregoing claims, wherein said method comprises a plurality of introductions of one or more polymers.

7. The method of claim 6, wherein said plurality of introductions occurs at one time-point in said method.

8. The method of claim 6 or claim 7, said plurality of introductions comprises at least one introduction occurring at a first time-point of said method, and at least one introduction occurring at a second time-point of said method, wherein said first time-point and second time-point are different from one another.

9. The method of any one of the foregoing claims, wherein said method comprises the introduction of several different flocculants.

10. The method of claim 9, wherein said flocculants comprise a polymer comprising one or more monomers of the following: acryloyloxy ethyl trimethyl ammonium chloride ("AETAC"); methacryloyloxyethyltrimethylammonium chloride;
methacrylamidopropyltrimethylammonium chloride ("MAPTAC");
acrylamidopropyltrimethylammonium chloride;

methacryloyloxyethyldimethylammonium sulfate; dimethylaminoethyl acrylate;
dimethylaminopropylmethacrylamide; Q6; Q6o 4; diallyldimethylammonium chloride ("DADMAC"); calcium diacrylate ("CDA"); acrylamide; acrylic acid; any monomer substituted with a carboxylic acid group or salt thereof; 2-acrylamido-2-methylpropane sulfonic acid ("AMPS"); ethylene oxide; propylene oxide; functionalized ethylene oxide;
epoxide; functionalized propylene oxide; epoxy or glycidyl ether functionalized hydrophobic monomers; 1 ,2-epoxy tetradecane; 2-ethylhexylglycidyl ether; 2, 2, 3, 3, 4, 4, 5, 5-octafluoropentyl ether; benzyl glycidyl ether; 4-nonylphenyl glycidyl ether; silane-or siloxane-functionalized glycidyl ethers; silane or siloxane-functionalized monomers;
3-glycidyloxypropyl polydimethyl siloxane; 3-glycidyloxypropyl trimethoxysilane; 3-glycidoxypropyldimethylethoxysilane; alkylene oxide; olefin oxide; aliphatic, cycloaliphatic or mixed aliphatic/cycloaliphatic alkylene oxide; alkylene oxide substituted by one or more aromatic radicals; 1,2-epoxybutane; 2,3-epoxybutane; the epoxypentanes; the epoxyhexanes; the epoxyoctanes; the epoxydecanes; the epoxydodecanes; 2,4,4-trimethyl-1,2-epoxypentane; 2,4,4-trimethyl-2,3-epoxypentane;
cyclohexylepoxythane; 7-oxabicyclo[4.1.0]heptane; 6-oxabicyclo[3.1.0]hexane; 3-methyl-6-oxabicyclo[3.1.0]hexane; 4-ethyl-6-oxabicyclo[3.1.0]hexane; styrene oxide; 1 -phenyl- 1 ,2-epoxypropane; 1,2-butylene oxide; 2,3-butylene oxide; the epoxypentanes, the epoxyhexanes; 2,3-epoxyheptane; nonene oxide; 5-butyl-3,4-epoxyoctane; 1 ,2-epoxydodecane; 1,2-epoxyhexadecane; 1 ,2-epoxyoctadecane; 5-benzyl-2,3-epoxyheptane; 4-cyclo-hexyl-2,3-epoxypentane; chlorostyrene oxide; styrene oxide;
ortho-, meta-, and para-ethylstyrene oxide; glycidyl benzene; the oxabicycloalkanes;
alkyl-substituted oxabicycloalkanes, e.g., 7-oxabicyclo[4.1.0]heptane;
oxabicyclo[3.1.0]hexane; 4-propyl-7-oxabicyclo[4.1.0]heptane; and/or 3-amyl-6-oxabicyclo[3.1 .O.Jhexane.].

11. The method of any one of the foregoing claims, wherein the pH of said tailings is adjusted more than one time during said method.

12. The method of any one of the foregoing claims, wherein the pH of said tailings before said pH adjustment is about 6.60 or higher.

13. The method of any one of the foregoing claims, wherein the pH of said tailings before said pH adjustment is about 6.60 or higher, 6.70 or higher, 6.80 or higher, 6.90 or higher, 7.00 or higher, 7.10 or higher, 7.20 or higher, 7.30 or higher, 7.40 or higher, 7.50 or higher, 7.60 or higher, 7.70 or higher, 7.80 or higher, 7.90 or higher, 8.00 or higher, 8.10 or higher, 8.20 or higher, 8.30 or higher, 8.40 or higher, 8.50 or higher, 8.60 or higher, 8.70 or higher, 8.80 or higher, 8.90 or higher, 9.00 or higher, 9.10 or higher, 9.20 or higher, 9.30 or higher, 9.40 or higher, 9.50 or higher, 9.60 or higher, 9.70 or higher, 9.80 or higher, 9.90 or higher, or 10.00 or higher.

14. The method of any one of the foregoing claims, wherein the pH of said tailings after said pH adjustment is about 6.50 or lower.

15. The method of any one of the foregoing claims, wherein the pH of said tailings after said pH adjustment is about 6.50 or lower, 6.40 or lower, 6.30 or lower, 6.20 or lower, 6.10 or lower, 6.00 or lower, 5.90 or lower, 5.80 or lower, 5.70 or lower, 5.60 or lower, 5.50 or lower, 5.40 or lower, 5.30 or lower, 5.20 or lower, 5.10 or lower, 5.00 or lower, 4.90 or lower, 4.80 or lower, 4.70 or lower, 4.60 or lower, 4.50 or lower, 4.40 or lower, 4.30 or lower, 4.20 or lower, 4.10 or lower, or 4.00 or lower.

16. The method of any one of the foregoing claims, wherein said method comprises the following steps:
a. a first introduction of one or more polymers;
b. flocculation;
c. floc conditioning;
d. mechanical dewatering;
e. solid-liquid (cake-centrate) separation; and f. cake deposition for continued cake drying and/or dewatering.

17. The method of any one of the foregoing claims, wherein said method comprises the following steps:
a. a first introduction of one or more polymers;
b. flocculation c. floc conditioning;
d. mechanical dewatering;
e. solid-liquid (cake-centrate) separation; and f. cake deposition for continued cake drying and/or dewatering;

and further wherein said one or more polymers begin to mix with the tailings prior to a pH adjustment.

18. The method of claim 16 or claim 17, wherein said method comprises a plurality of introductions of one or more polymers.

19. The method of any one of claims 16-18, wherein one or more additional polymer introductions occur during and/or after step a. and not after step d.

20. The method of claims 16-19, wherein the pH of said tailings is adjusted not before step a.
and not after step d.

21. The method of any one of claims 16-20, wherein pH adjustment occurs during and/or after a first polymer introduction.

22. The method of any one of claims 16-21, wherein pH adjustment occurs before, during, and/or after flocculation.

23. The method of any one of claims 16-22, wherein pH adjustment occurs before, during, and/or after floc conditioning.

24. The method of any one of claims 16-23, wherein pH adjustment occurs before or during mechanical dewatering.

25. The method of any one of the foregoing claims, wherein said method comprises one or more introductions of one or more flocculants.

26. The method of any one of the foregoing claims, wherein said tailings comprise oil sands tailings; mature fine tailings; fluid fine tailings; tailings from coal mining, copper mining, aluminum mining, nickel mining, gold mining, and/or mineral processing; and/or in-process tailings.

27. The method of any one of the foregoing claims, wherein said tailings comprise oil sands tailings.

28. The method of any one of the foregoing claims, wherein said tailings comprise mature fine tailings.

29. The method of any one of the foregoing claims, wherein said mechanical dewatering method comprises centrifugation, thin lift, and/or the introduction of one or more thickeners.

30. The method of any one of the foregoing claims, wherein said method comprises centrifugation as a mechanical dewatering step.

31. The method of any one of the foregoing claims, wherein said method comprises the introduction of cationic, neutral or anionic flocculants or a combination of any of the foregoing.

32. The method of claim 31, wherein said flocculants comprise one or more polymers, comprising one or more monomers of the following: acryloyloxy ethyl trimethyl ammonium chloride ("AETAC"); methacryloyloxyethyltrimethylammonium chloride;
methacrylamidopropyltrimethylammonium chloride ("MAPTAC");
acrylamidopropyltrimethylammonium chloride;
methacryloyloxyethyldimethylammonium sulfate; dimethylaminoethyl acrylate;
dimethylaminopropylmethacrylamide; Q6; Q6o 4; diallyldimethylammonium chloride ("DADMAC"); calcium diacrylate ("CDA"); acrylamide; acrylic acid; any monomer substituted with a carboxylic acid group or salt thereof; 2-acrylamido-2-methylpropane sulfonic acid ("AMPS"); ethylene oxide; propylene oxide; functionalized ethylene oxide;
epoxide; functionalized propylene oxide; epoxy or glycidyl ether functionalized hydrophobic monomers; 1 ,2-epoxy tetradecane; 2-ethylhexylglycidyl ether; 2, 2, 3, 3, 4, 4, 5, 5-octafluoropentyl ether; benzyl glycidyl ether; 4-nonylphenyl glycidyl ether; silane-or siloxane-functionalized glycidyl ethers; silane or siloxane-functionalized monomers;
3-glycidyloxypropyl polydimethyl siloxane; 3-glycidyloxypropyl trimethoxysilane; 3-glycidoxypropyldimethylethoxysilane; alkylene oxide; olefin oxide; aliphatic, cycloaliphatic or mixed aliphatic/cycloaliphatic alkylene oxide; alkylene oxide substituted by one or more aromatic radicals; 1,2-epoxybutane; 2,3-epoxybutane; the epoxypentanes; the epoxyhexanes; the epoxyoctanes; the epoxydecanes; the epoxydodecanes; 2,4,4-trimethyl-1,2-epoxypentane; 2,4,4-trimethyl-2,3-epoxypentane;
cyclohexylepoxythane; 7-oxabicyclo[4.1.0]heptane; 6-oxabicyclo[3.1.0]hexane; 3-methyl-6-oxabicyclo[3.1.0]hexane; 4-ethyl-6-oxabicyclo[3.1.0]hexane; styrene oxide; 1 -phenyl- 1 ,2-epoxypropane; 1,2-butylene oxide; 2,3-butylene oxide; the epoxypentanes, the epoxyhexanes; 2,3-epoxyheptane; nonene oxide; 5-butyl-3,4-epoxyoctane; 1 ,2-epoxydodecane; 1,2-epoxyhexadecane; 1 ,2-epoxyoctadecane; 5-benzyl-2,3-epoxyheptane; 4-cyclo-hexyl-2,3-epoxypentane; chlorostyrene oxide; styrene oxide;
ortho-, meta-, and para-ethylstyrene oxide; glycidyl benzene; the oxabicycloalkanes;
alkyl-substituted oxabicycloalkanes, e.g., 7-oxabicyclo[4.1.0]heptane;

oxabicyclo[3.1.0]hexane; 4-propyl-7-oxabicyclo[4.1.0]heptane; and/or 3-amyl-6-oxabicyclo[3.1.OJhexane.]..

33. The method of any one of the foregoing claims, wherein the pH of said tailings is not adjusted prior to a first introduction of one or more polymers.

34. The method of any one of the foregoing claims, wherein the pH of said tailings or a portion thereof prior to a first introduction of said one or more polymers is or is adjusted to between about 7.0 to about 10.0 inclusive.

35. The method of claim 34, wherein said pH adjustment of the tailings to a pH
between about 7.0 to about 10.0 inclusive may occur in a single step or said pH
adjustment may be effected in several steps.

36. The method of any one of the foregoing claims, wherein said method comprises a centrate solids content of 1.00% or less, 0.95% or less, 0.90% or less, 0.85%
or less, 0.80% or less, 0.75% or less, 0.70% or less, 0.65% or less, 0.60% or less, 0.55% or less, 0.50% or less, 0.45% or less, 0.40% or less, 0.35% or less, 0.30% or less, 0.25% or less, 0.20% or less, 0.15% or less, or 0.10% or less that results from treating said tailings.

37. The method of any one of the foregoing claims, wherein said method comprises a cake solids content of 40.0% or more, 40.5% or more, 41.0% or more, 41.5% or more, 42.0%
or more, 42.5% or more, 43.0% or more, 43.5% or more, 44.0% or more, 44.5% or more, 45.0% or more, 45.5% or more, 46.0% or more, 46.5% or more, 47.0% or more, 47.5%
or more, or 48.0% or more, 48.5% or more, 49.0% or more, 49.5% or more, 50.0%
or more, 50.5% or more, 51.0% or more, 51.5% or more, 52.0% or more, 52.5% or more, 53.0% or more, 53.5% or more, 54.0% or more, 54.5% or more, 55.0% or more, 55.5%
or more, 56.0% or more, 56.5% or more, 57.0% or more, 57.5% or more, 58.0% or more, 58.5% or more, 59.0% or more, 59.5% or more, 60.0% or more, 60.5% or more, 61.0%
or more, 61.5% or more, 62.0% or more, 62.5% or more, 63.0% or more, 63.5% or more, 64.0% or more, 64.5% or more, or 65.0% or more that results from treating said tailings.

38. The method of any one of the foregoing claims, wherein said method comprises introduction of a polymer comprising acrylamide monomers.

39. The method of any one of the foregoing claims, wherein said method comprises introduction of a copolymer comprising acrylamide monomers and acrylic acid monomers.

40. The method of any one of the foregoing claims, wherein said method comprises introduction of a polymer comprising acrylic acid monomers.

41. The method of claim 39 or claim 40, wherein said acrylic acid monomers comprise a monomer percentage of 10% or more, 15% or more, 20% or more, 25% or more, 30%
or more, 35% or more, 40% or more, 45% or more, 50% or more, 60% or more, 70% or more, 80% or more, or 90% or more, 95% or more, 99% or more.

42. The method of claim 40, wherein said acrylic acid monomers comprise a monomer percentage of 100%.

43. The method of any one of the foregoing claims, wherein said pH adjustment is effected by introducing an acid and/or highly acidic dispersant, coagulant, flocculant, or any other process additive product.

44. The method of any one of the foregoing claims, wherein said method comprises introduction of a polymer at a concentration of 1 ppm or less, 10 ppm or less, 25 ppm or less, 50 ppm or less, 50 ppm or more, 100 ppm or more, 200 ppm or more, 300 ppm or more, 400 ppm or more, 500 ppm or more, 600 ppm or more, 700 ppm or more, 800 ppm or more, 900 ppm or more, 1000 ppm or more, 1100 ppm or more, 1200 ppm or more, 1300 ppm or more, 1400 ppm or more, 1500 ppm or more, 1600 ppm or more, 1700 ppm or more, 1800 ppm or more, 1900 ppm or more, or 2000 ppm or more.

45. The method of any one of the foregoing claims wherein the amount of introduced polymer or polymers is selected based on MFT solids concentration and/or the means of mechanical dewatering.

46. The method of any one of the foregoing claims, wherein said method comprises introduction of a polymer in dry form, e.g., a dry polyacrylamide (DPAM)-based polymer.

47. The method of any one of the foregoing claims, wherein said one or more polymers and/or said one or more flocculants begin to mix with said tailings before said pH
adjustment occurs.

48. The method of any one of the foregoing claims, wherein said introduction of one or more polymers comprises injection, pouring, and/or dripping.

49. A product produced by the method of any one of the foregoing claims.