CA3012250A1 - Treatment of froth tailings from oil sands processing - Google Patents

Abstract

Processes of consolidating bitumen froth tailings which includes fines and process water are disclosed. The processes include mixing the bitumen froth tailings with a highly water soluble salt or an aqueous solution thereof to destabilize and consolidate solids in the tailings, e.g., to destabilize and consolidate fines in the tailings and separating the consolidated solids from the process water. A water soluble polymer flocculant and coarse particles, e.g., sand, can also be used in the treatment of bitumen froth tailings. Residual hydrocarbons in the bitumen froth tailings can optionally be recovered.

Description

TREATMENT OF FROTH TAILINGS FROM OIL
SANDS PROCESSING
TECHNICAL FIELD
[0001] The present disclosure relates to dewatering and consolidation of froth tailings from oil sands extraction processes. Residual hydrocarbons present in the froth tailings can also be separated and recovered.
BACKGROUND

[0002] The separation and extraction of oil and bitumen from soil, sand, or other forms of mineral matter is a difficult and expensive process. The commercial operations presently used to extract bitumen from Canadian oil sands involve crushing oil sand ore and combining it with hot or warm water and chemical aids such as sodium hydroxide (NaOH) to form a slurry. The chemical aids, together with the mechanical action of transporting the slurry through a hydrotransport pipeline, help to detach bitumen from oil sand particles. At the extraction plant, the conditioned slurry is discharged into primary separation vessels and bitumen is separated from solids by aeration to form a bitumen containing froth that can be skimmed off the surface of the water. The solids, mainly sand and some fines, together with process-affected water, are discharged as a tailings slurry to a tailings pond. The term fines as used herein is consistent with the Canadian oil sands classification system and means solid particles with sizes equal to or less than 44 microns (pm). Sand is considered solid particles with sizes greater than 44 rim.

[0003] Bitumen froth is an emulsion of bitumen (about 50%-60%), water (about 30%-40%) and solids (about 10%-14%), mostly but not entirely mineral fines. The components of this emulsion are not easily separated. To reduce interfacial tension, reduce viscosity and provide a density difference, a diluent or solvent is added, followed by various forms of enhanced gravity separation. Like primary separation, froth treatment produces tailings, which in most commercial operations is also discharged as a separate stream to tailings ponds, where it combines with the tailings deposited from the primary separation cells.

[0004] The management and sustainability of tailings ponds pose significant and growing problems. It is estimated that tailings ponds associated with Canadian oil sands operations now cover an area of more than 200 km2. Reclamation efforts have had limited success and the ponds DM_US 153846401-2 098351 0041 continue to grow in size. The tailings ponds contain components that are toxic to aquatic life and the water cannot be discharged to natural waterways such as the Athabasca River. Because of the presence of fine particles, a gel-like layer of so-called mature fine tailings also develops in the ponds. It is estimated that under the action of gravity alone, this component would take more than a century to consolidate and settle.

[0005] Although froth tailings are a small component of the tailings produced (2-4%) from oil sands extraction, they contain most of the components that are considered problematic, including significant residues of bitumen among other hydrocarbons including the diluent or solvents used to extract the bitumen. Froth tailings also have somewhat elevated concentrations of pyrite, naturally occurring radioactive materials, and some heavy metals.

[0006] Treating the froth tailings as a separate stream before it enters tailings ponds would therefore confer significant environmental advantages and improvements to current processes. It would enable operators to apply different suites of tailings technologies to this stream, facilitate reclamation by removing the most toxic components, and reduce fugitive emissions associated with residual pollutants.
SUMMARY OF THE DISCLOSURE

[0007] Advantages of the present disclosure include processes to treat bitumen froth tailings to dewater the tailings to produce high solids content materials.
Additional advantageous can include separating hydrocarbons from the tailings.

[0008] These and other advantages are satisfied, at least in part, by a process of consolidating bitumen froth tailings. The process comprises treating the bitumen froth tailings, which include fines and process water, with a highly water soluble salt.
Advantageously, the process can include treating the bitumen froth tailings with the at least one highly water soluble salt or solution thereof and can optionally include either or both of at least one polymer flocculant or solution thereof and/or coarse particles, e.g., sand, to form a treated tailings. The treated tailings can include a consolidated material in the process water. The process water can then be advantageously separated from the consolidated material.

[0009] Implementations of the process of the present disclosure include, for example, (i) treating the bitumen froth tailings with at least one highly water soluble salt to form a treated Dm_us 53846401-2.0983511 0041 tailings including a consolidated material in the process water, (ii) treating the bitumen froth tailings with at least one highly water soluble salt and at least one polymer flocculant to form a treated tailings including a consolidated material in the process water, (iii) treating the bitumen froth tailings with at least one highly water soluble salt thereof, and coarse particles to form a treated tailings including a consolidated material in the process water, and (iv) treating the bitumen froth tailings with at least one highly water soluble salt, at least one polymer flocculant and coarse particles to form a treated tailings including a consolidated material in the process water. Each of these implementations can include aqueous solutions of the salt and/or polymer flocculant to treat the tailings. Each of these implementations can include separating the process water from the consolidated material.

[0010] In practicing aspects of the processes, bitumen froth tailings that include hydrocarbon, such as tar, crude oil, heavy oil, or other hydrocarbon oil, bitumen, asphaltenes, etc. or diluents or solvents or any combinations thereof, can be separated and recovered. The process can further comprise treating the tailings with a diluent to dilute the hydrocarbon and recovering the diluted hydrocarbon. Advantageously, the hydrocarbon separated from the tailings can contain a low amount of fines or has low minerals content, e.g., less than about 1 wt% or no more than about 0.5 wt% or no more than about 0.1 wt%.

[0011] In practicing aspects of the processes of the present disclosure and the various embodiments thereof, the separated process water can include the at least one highly water soluble salt and the process can further comprise: one or more of: (i) recovering at least a portion of the separated process water; (ii) recycling at least a portion of recovered separated process water to treat additional bitumen froth tailings; (iii) purifying at least a portion of recovered process water and/or (iv) concentrating the at least one highly water soluble salt in recovered process water to form a brine and using the brine to treat additional bitumen froth tailings. Such concentration can be carried out by reverse osmosis, for example.

[0012] Yet another aspect of the present disclosure includes recovering the consolidated materials from the tailings. Advantageously, the processes of the present disclosure can consolidate the solids of the tailings to produce a consolidated material having a solids content in excess of about 45% by weight, e.g., a solids content of greater than about 50% and higher than about 60%, 65%, 70% and 75% by weight.
DM_US 153846401-2 098351 0041

[0013] Embodiments of the processes include one or more of the following features individually or combined. For example, in some embodiments the at least one highly water soluble salt can have a solubility in water (a salt/water solubility) of at least about 5 g/100 g at 20 C, e.g., at least about 10 g/100 g at 20 C. In other embodiments, the at least one highly water soluble salt is a non-hydrolyzing salt. In still further embodiments, the at least one highly water soluble salt can have a monovalent cation and can include an ammonium based salt, a phosphate based salt, or a sulfate based salt.

[0014] In certain embodiments, the treated tailings can have a salt-tailings concentration of at least 0.5 wt% of the at least one highly water soluble salt and preferably no less than about 1 wt%, such as at least about 2 wt% and even greater than about 3 wt%, 4 wt%, 5 wt%, etc. of the at least one highly water soluble salt. In other embodiments, treating bitumen froth tailings includes using a solution of one or more highly soluble salts sourced from a natural or existing source, e.g., seawater or a body of hypersaline water. In some embodiments, the at least one polymer flocculant is a polyacrylamide or co-polymer thereof The treated tailings can have a polymer-tailings concentration of the at least one polymer flocculant of no less than zero and up to about 0.001 wt%, e.g., up to about 0.003 wt%, 0.005 wt%, 0.01 wt% or 0.04 wt%.
Advantageously, the polymer flocculant forms high density flocs, e.g., having a density greater than the process water, which facilitates separation and dewatering of the consolidated solids. In other embodiments, the tailings also can be treated with coarse particles, e.g., sand, at a sand to fines ratio of less than 4:1, e.g., between about 2.5:1.0 to 0.5:1 or between about 2.25:1 to about 0.75:1.

[0015] In various embodiments, treating the tailings can include combining the bitumen froth tailings with a solution including the at least one highly water soluble salt and the at least one polymer flocculant. In some embodiments, treating the tailings can include combining a stream of the oil sands tailing with a stream of a solution including the at least one highly water soluble salt and a separate stream of a solution including the at least one polymer flocculant.
Alternatively, or in combination, treating the tailings can include combining a stream of the bitumen froth tailings with a stream of a solution including both the at least one highly water soluble salt and the at least one polymer flocculant. Coarse particles (sand) can also be added to the bitumen froth tailings or stream thereof and/or to any or all of the solution streams.
DM_US 1538464O1-2.O98351 0041 Advantageously, the streams can be mixed inline and/or with the aid of an inline mixer. In certain embodiments, treating the bitumen froth tailings can be carried out at a temperature of no more than 50 C, e.g., no more than about 40 C or 30 C. In other embodiments, treating the composition includes using a solution of one or more highly soluble salts sourced from a natural or existing source such as seawater or a body of hypersaline water.

[0016] In still further embodiments, the process water can be separated from the consolidated material by any one or more of decanting, filtering, vacuuming, gravity draining, etc. or combinations thereof. In various embodiments, separating the process water from the consolidated material can include mechanically dewatering the consolidated material, e.g., mechanically dewatering the consolidated material by a dewatering screw. Once separated, the consolidated material can be transferred for further dewatering or disposal.

[0017] In practicing certain aspects of the processes of the present disclosure and the various embodiments thereof, the consolidated material formed in the treated tailings according to certain embodiments can result in a high solids content after mixing and/or dewatering the treated tailings in a short period of time. In some embodiments, the consolidated material can have a solids content of greater than about 50% and at least about 60%, 65%, 70%, 75% and 80% by weight after mixing and/or dewatering. In certain embodiments a solids content of at least about 70 % is achieved within about one month of gravity draining after treating the tailings, e.g., within about two weeks or within about one week of gravity draining after treating the tailings.

[0018] Additional advantages of the present invention will become readily apparent to those skilled in this art from the following detailed description, wherein only the preferred embodiment of the invention is shown and described, simply by way of illustration of the best mode contemplated of carrying out the invention. As will be realized, the invention is capable of other and different embodiments, and its several details are capable of modifications in various obvious respects, all without departing from the invention. Accordingly, the drawings and description are to be regarded as illustrative in nature, and not as restrictive.
Dmiis 153846401-2 098351 0041 BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Reference is made to the attached drawings, wherein elements having the same reference numeral designations represent similar elements throughout and wherein:

[0020] Figure 1 schematically illustrates an exemplary embodiment of a process of consolidating bitumen froth tailings.

[0021] Figure 2A is a picture of a vial containing bitumen froth tailings sample.

[0022] Figure 2B is a picture of a vial containing bitumen froth tailings after treatment with a highly soluble salt and polymer flocculant followed by centrifugation in accordance with certain embodiments of the present disclosure.

[0023] Figure 3 is a picture of vials containing bitumen froth tailings treated with a highly soluble salt, polymer flocculant and sand.

[0024] Figure 4 is a picture of vials containing bitumen froth tailings treated with a highly soluble salt, polymer flocculant, sand and a diluent.
DETAILED DESCRIPTION OF THE DISCLOSURE

[0025] The present disclosure relates to treating bitumen froth tailings to consolidate and dewater the tailings. As described in the background section, bitumen froth tailings are a waste by-product of the process of extracting bitumen from oil sands and include process water, fines, and hydrocarbons such as tar, crude oil, heavy oil, or other hydrocarbon oil, bitumen, asphaltenes, etc. or diluents or solvents or any combinations thereof. In certain aspects, treating the bitumen froth tailings can also include separating and recovering the hydrocarbons from the tailings. Advantageously, the process of the present disclosure can consolidate the solids of the tailings to produce consolidated material having a solids content in excess of about 45% by weight, e.g., a solids content of greater than about 50% and higher than about 60%, 65%, 70%
and 75% by weight.

[0026] The solids of bitumen froth tailings are classified according to particle sizes. The term fines as used herein is consistent with the Canadian oil sands classification system and means solid particles with sizes equal to or less than 44 microns (im). Sand is considered solid particles with sizes greater than 44 [im. Oil sands deposits include a significant amount of fines, e.g., 10-30 wt%. The tailings from oils sands extraction can also include a significant amount of DM_US 153846401-2 098351 0041 fines by weight (>5 wt%) as their solids content. Such tailings can include at least about 10 wt%, 20 wt%, 30 wt%, 40 wt%, 50 wt%, 60 wt%, 70 wt% or higher fines as their solids content.

[0027] The terms coagulation and flocculation are often used interchangeably in the literature. As used herein, however, coagulation means particle aggregation brought about by the addition of hydrolyzing salts, whereas flocculation means particle aggregation induced by flocculating polymers. Hydrolyzing salts undergo hydrolysis when added to water to form metal hydroxides, which precipitate from the solution, trapping fines and other minerals in the coagulating mass. Hydrolyzing salts typically have low solubility in water and are used as coagulants. Aggregation induced by flocculation, in contrast, is believed to be the result of the polymer binding to the particles thereby tying the particles together into a so called floc causing aggregation of the particles.

[0028] In practicing aspects of the present disclosure, bitumen froth tailings, e.g., a suspension of particulate solids in an aqueous liquid which include fines and process water, can be consolidated by treating the bitumen froth tailings with one or more highly water soluble salt(s) or an aqueous solution thereof to destabilize and consolidate solids in the tailings, e.g., to destabilize and consolidate fines in the tailings. Aggregation induced by the addition of salts is believed to be the result of destabilizing the particles suspended in the fluid by an alteration or a shielding of the surface electrical charge of the particles to reduce the inter-particle repulsive forces that prevent aggregation. The process water can then be separated from the consolidated material. Advantageously, the consolidated material has a solids content of at least 45% by weight, e.g., a solids content of greater than about 50% by weight.

[0029] Salts that are useful in practicing the present disclosure include salts that are highly soluble in water. A highly water soluble salt as used herein is one that has a solubility in water of greater than 2 g of salt per 100 g of water (i.e., a salt/water solubility of 2g/100g) at 20 C. Preferably the highly water soluble salt has a water solubility of at least about 5 g/100 g at 20 C, e.g., at least about 10 g/100 g of salt/water at 20 C.

[0030] In addition, the highly water soluble salts used in the processes of the present disclosure are preferably non-hydrolyzing. Hydrolyzing salts undergo hydrolysis when added to water to form metal hydroxides, which precipitate from the solution. Such hydrolyzing salts are believed to form open flocs with inferior solids content and cannot be readily recycled for use DM_US 153846401-2 098351 0041 with additional tailings in continuous or semi-continuous processes. In addition, hydrolyzing salts typically have low solubility in water and are used at elevated temperatures to ensure sufficient solubility for aggregation, which is an energy intensive process.
See US 4,225,433 which discloses the use of lime as a coagulating agent at a temperature of 75 C.

[0031] Further, the highly water soluble salts are preferably not carboxylate salts since such organic acid salts tend to be more expensive than inorganic salts and can be deleterious to plant and/or animal life.

[0032] Highly water soluble salts that are not hydrolyzing and useful in practicing processes of the present disclosure include salts having a monovalent cation, e.g., alkali halide salts such as sodium chloride, potassium chloride; also salts with monovalent cations such as sodium nitrate, potassium nitrate, sodium and potassium phosphates, sodium and potassium sulfates, etc. are useful in practicing processes of the present disclosure.
Other monovalent cationic salts useful in practicing processes of the present disclosure include ammonium based salts such as ammonium acetate (NH4C2H302), ammonium chloride (NH4C1), ammonium bromide (NH413r), ammonium carbonate ((NH4)2CO3), ammonium bicarbonate (NH4HCO3), ammonium nitrate (NH4NO3), ammonium sulfate ((NH4)2SO4), ammonium hydrogen sulfate (NH4HSO4), ammonium dihydrogen phosphate (NH4H2PO4), ammonium hydrogen phosphate ((NH4)2HPO4), ammonium phosphate ((NH4)3PO4), etc. Mixtures of such salts can also be used.

[0033] Ammonium based salts are useful for practicing the present disclosure since residual ammonium based salts on the consolidated material after combining the salt with the bitumen froth tailings are not harmful to plant life. In fact, many of the ammonium based salts are useful as fertilizers and are in fact beneficial to plant life, e.g., ammonium chloride, ammonium nitrate, ammonium sulfate, etc. Many of the monovalent sulfate and phosphate salts are also useful as fertilizers. In certain embodiments of the present disclosure, the highly water soluble salt or salts used in the processes of the present disclosure can preferably be non-toxic and beneficial to plant life to aid in environmental remediation and the restoration of mine sites.

[0034] In one aspect of the present disclosure, treating bitumen froth tailings with a highly water soluble salt destabilizes and consolidates solids in the tailings. Such a process can include mixing the bitumen froth tailings, which includes fines and process water, with a highly water soluble salt to consolidate the fines, and separating the process water from the consolidated DM_US 153846401-2 098351 0041 fines to produce a high solids content, e.g., at least 45% by weight. In certain embodiments, the highly water soluble salt is an ammonium based salt.

[0035] Highly water soluble salts that can be used in practicing the present process can also include salts having multivalent cations. Such salts include, for example, divalent cation salts such as calcium and magnesium cation salts, such as calcium chloride (CaCl2), calcium bromide (CaBr2), calcium nitrate (Ca(NO3)2), magnesium chloride (MgCl2), magnesium bromide (MgBr2), magnesium nitrate (Mg(NO3)2), magnesium sulfate (MgSO4); and trivalent cation salts such as aluminum and iron (III) cation salts, e.g., aluminum chloride (A1C13), aluminum nitrate (Al(NO3)3), aluminum sulfate (Al2(SO4)3), iron (III) chloride (FeC13), iron (III) nitrate (Fe(NO3)3), iron (III) sulfate (Fe2(SO4)3, etc. As explained above, the highly water soluble salts used in the processes of the present disclosure are preferably non-hydrolyzing. Many of the multivalent cation salts are hydrolyzing and thus less preferred for the reasons stated above.
Moreover, experimentation with multivalent salts showed increased fouling of containers and formation of less cohesive consolidated materials as compared to highly water soluble salts having monovalent cations. In addition, some multivalent salts, such as FeCl3 and Fe2(SO4)3, are particularly corrosive and Fe2(SO4)3 is formed from oxidizing pyrite and results in acid mine run-off, which make such salts less preferable for use in processes of the present disclosure.

[0036] We found that when a sufficiently high concentration of the highly water soluble is included in the treated tailings, the salt can destabilize and consolidate solids in the tailings.
For a relatively short process times with a relatively low energy input, the salt-tailings concentration of the at least one highly water soluble salt should preferably be at least 0.5 wt%
and preferably no less than about 1 wt%, such as at least about 2 wt% and even at least about 3 wt%, 4 wt%, 5 wt%, etc. The term "salt-tailings concentration" as used herein refers to the concentration of the highly water soluble salt(s) in the treated tailings and is determined by taking the percentage of the mass of highly water soluble salt(s) divided by the combined mass of the salt(s) plus the tailings and any water used to dilute the salt(s). For example, combining 1 part undiluted (i.e., neat) salt to 99 parts tailings by weight results in a salt-tailings concentration of 1 wt%. Alternatively, treating bitumen froth tailings with an equal weight of a 2 wt% solution of the salt also results in a salt-tailings concentration of 1 wt% in the treated tailings.
DM_US 153846401-2 098351 0041

[0037] The highly water soluble salt(s) can be used to treat bitumen froth tailings as a solid, e.g., combining the salt as a powder with the tailings. Alternatively, the salt can be used to treat bitumen froth tailings as a solution, e.g., combining an aqueous salt solution with the tailings. In some aspects of the present disclosure, an aqueous solution of the highly water soluble salt can be prepared having a concentration of no less than about 1 wt%, e.g., greater than about 2 wt%, 3 wt%, 5 wt%, 7 wt%, 10 wt%, 20 wt%, 30 wt% and even as great as a 40 wt% or as an aqueous salt slurry.

[0038] In some embodiments of the present processes, it can be more advantageous to use a natural source of a highly soluble salt or salts such as in a natural body of water including such salts in sufficiently high concentration such as at least about 2 wt% and even at least about 3 wt% or greater. For example, ocean or seawater can be used as a source of highly soluble salts, which can significantly improve the economics of the process under certain conditions. The vast majority of seawater has a salinity of between 31 g/kg and 38 g/kg, that is, 3.1-3.8%. On average, seawater in the world's oceans has a salinity of about 3.5% (35 g/L, 599 mM).
Seawater includes of a mixture of salts, containing not only sodium cations and chlorine anions (together totaling about 85% of the dissolved salts present), but also sulfate anions and calcium, potassium and magnesium cations. There are other ions present (such as bicarbonate), but these are the main components. Another natural source of highly soluble salts that can be used as a source of highly soluble salts includes a hypersaline body of water, e.g., a hypersaline lake, pond, or reservoir. A hypersaline body of water is a body of water that has a high concentration of sodium chloride and other highly soluble salts with saline levels surpassing ocean water, e.g., greater than 3.8 wt% and typically greater than about 10 wt%. Such hypersaline bodies of water are located on the surface of the earth and also subsurface, which can be brought to the surface as a result of oil sands mining operations.

[0039] The bitumen froth tailings and salt solution or slurry should be mixed at a ratio sufficient to destabilize the tailings and/or cause consolidation of the solids therein. In one aspect of the present disclosure, the bitumen froth tailings and the salt solution are mixed

[0040] at a ratio within a range of about 5.0:1.0 to about 1.0:5.0, e.g., mixed at a ratio within a range of about 3:1 to about 1:3, such as about 1.5:1.0 to about 1.0:1.5 bitumen froth tailings to salt solution.

[0041] After treating the bitumen froth tailings with at least one highly water soluble salt the solids in the tailings can be consolidated such as by mixing followed by gravity sedimentation in a settling tank or by centrifugation to increase the rate of forming a consolidated material in the treated tailings. The consolidated material can be separated from the process water by decanting, filtering, electrofiltration, cross-flow filtering, vacuuming, and/or by mechanical dewatering, i.e., applying an external force to the consolidated material. Once separated, the consolidated material can be transferred for further dewatering or disposal.

[0042] The process of the present disclosure allows for large scale treatment of bitumen froth tailings in a continuous or semi-continuous process. For example, the process water separated from an initial tailings treatment can advantageously include a significant amount of the one or more highly water soluble salt(s). This separated process water, or at least a portion thereof, can then be recovered and recycled to consolidate the solids of additional bitumen froth tailings by mixing the recovered process water with additional bitumen froth tailings. The highly water soluble salt(s) in the recovered process water can be concentrated and/or additional highly water soluble salt(s) added to formulate a solution from the recovered process water for use in treating additional bitumen froth tailings.

[0043] Although highly water soluble salts can destabilize and consolidate solids in the tailings, it was found that the process could be significantly improved by including one or more polymer flocculant(s) to the process. Including a polymer flocculant to the process of treating tailings with a highly water soluble salt can significantly reduce the time for consolidation of fines.

[0044] In addition, the processes of the present disclosure can also include treating bitumen froth tailings with coarse particles, e.g., particles with sizes greater than 44 pin, such as sand, to significantly increase the solids content. It is believed that use of coarse particles such as sand are needed to increase the solids content of the tailings to greater than about 60% without use of thermal treatments or long processing times. While treating bitumen froth tailings with water soluble salt(s) and coarse particles without polymer flocculant(s) can consolidate solids in the tailings, such a process leads to a loose consolidation.

[0045] Hence, implementation of the process of the present disclosure include (i) treating bitumen froth tailings with at least one highly water soluble salt to form a treated tailings including a consolidated material in the process water, (ii) treating bitumen froth tailings with at least one highly water soluble salt and at least one polymer flocculant to form a treated tailings including a consolidated material in the process water, (iii) treating bitumen froth tailings with at least one highly water soluble salt thereof, and coarse particles to form a treated tailings including a consolidated material in the process water, and (iv) treating bitumen froth tailings with at least one highly water soluble salt, at least one polymer flocculant and coarse particles to form a treated tailings including a consolidated material in the process water. Each of these implementations can include aqueous solutions of the salt and/or polymer flocculant to treat the tailings. Each of these implementations can include separating the process water from the consolidated material. The process water can be readily separated from the consolidated material as, for example, by one or more of decanting, filtering, electrofiltering, cross-flow filtering, gravity draining, vacuuming and other evaporating techniques, etc. or combinations thereof and/or by one or more of a device for dewatering consolidated material such as a centrifuge, decanting centrifuge, dewatering screw, hydrocyclone, vacuum belt filter, filter press or pressing devices, etc. or combinations thereof. In addition, the separated consolidated material can be disposed or deposited in a containment structure which allows removal of released water from the consolidated material.

[0046]
Polymers that are useful in practicing the present disclosure include water soluble flocculating polymers such as polyacrylamides or copolymers thereof such as a nonionic polyacrylamide, an anionic polyacrylamide (APAM) and a cationic polyacrylamide (CPAM), which can contain co-monomers such as acryloxyethyltrimethyl ammonium chloride (DAC), methacryloxyethyltrimethyl ammonium chloride (DMC), dimethyldiallyammonium chloride (DMDAAC), etc. Other water soluble flocculating polymers useful for practicing the present disclosure include a polyamine, such as a polyamine or quaternized form thereof, e.g., polyacrylamide-co-dimethylaminoethylacrylate in quaternized form, a polyethyleneimine, a polydiallyldimethyl ammonium chloride, a polydicyandiamide, or their copolymers, a polyamide-co-amine, polyelectrolytes such as a sulfonated polystyrenes can also be used. Other water soluble polymers such as polyethylene oxide and its copolymers can be used. The polymer flocculants can be synthesized in the form of a variety of molecular weights (MW), electric charge types and charge density to suit specific requirements. Advantageously, the flocculating DM_US 153846401-2 098351 0041 polymer used in practicing processes of the present disclosure do not include use of activated polysaccharides or activated starches, i.e., polysaccharides and starches that have been heat treated, in sufficient amounts to lower the density of the floc to below the density of the process water from which they are separated. Such activated polysaccharides and activated starches when used in sufficiently high dosages tend to form low density flocs which rise to the surface of an aqueous composition complicating removal of hydrocarbon and can hinder removal of solids in large scale operations involving high solids content and can also hinder dewatering of consolidated material.

[0047] The amount of polymer(s) used to treat tailings should preferably be sufficient to flocculate the solids in the tailings and any added sand. The amount of polymer(s) used to treat tailings can be characterized as a concentration based on the total weight of the tailings or as a dosage based on the weight percent of the solids in the tailings.

[0048] In some embodiments of the present disclosure, the concentration of the one or more polymer flocculant(s) in the treated tailings has a polymer-tailings concentration of no less than zero and up to about 0.001 wt%, e.g., up to than about 0.003 wt%, 0.005 wt% or up to about 0.01 wt%. For relatively short processing times, consolidation of the fines/sand mixture can be obtained at polymer-tailings concentrations no less than about 0.04 wt%. The term "polymer-tailings concentration" as used herein refers to the concentration of the flocculating polymer(s) in the treated tailings and is determined by taking the percentage of the mass of the polymer(s) divided by the combined mass of the polymer(s) plus the tailings and any water used to dissolve the polymer(s). For example, combining 1 part undiluted (i.e., neat) polymer to 9999 parts tailings by weight results in a polymer-tailings concentration of 0.01 wt%.
Alternatively, treating bitumen froth tailings with an equal weight of a 0.02 wt% solution of the polymer also results in a polymer-tailings concentration of 0.01 wt%. In certain embodiments, bitumen froth tailings is treated with at least one polymer flocculant to yield a polymer-tailings concentration of up to about 0.02 wt%, such as up to about 0.03 wt%, 0.04 wt%, 0.05 wt%, and even at least about 0.07 wt%, 0.09 wt%, 0.1 wt%, 0.2 wt%, etc. The amount of polymer flocculant can be used in greater concentrations. However, after certain high concentrations it becomes difficult to dissolve the flocculant, the solution becomes too viscous and the process is less economical.
DM_US 153846401-2.098351 0041

[0049] In some embodiments of the present disclosure, the concentration of the one or more polymer flocculant(s) in the treated tailings has dosage (weight of the flocculant(s) to weight of the solids in the tailings) of up to about 0.005 wt%, e.g., up to about 0.01 wt% and preferably up to about 0.015 wt%, 0.020 wt%, 0.025 wt%, 0.03 wt%, or 0.04 wt%.

[0050] It was observed that the amount of polymer flocculant can be reduced if the salt-tailings concentration is increased. While the reason for this effect is not clear, a very low polymer-tailings concentration of up to about 0.001 wt%, e.g., up to about 0.003 wt%, 0.005, wt%, 0.01 wt%, 0.02 wt%, 0.03 wt%, 0.04 wt%, 0.05 wt %, for example, can achieve reasonably fast consolidation of solids in bitumen froth tailings if the salt-tailings concentration is increased.

[0051] Coarse particles useful for practicing processes according to the present disclosure are preferably sand and when used in treating tailings the amount of such particles are preferably in a sand to fines ratio (SFR ratio) of less than 4:1, e.g., between about 2.5:1.0 to 0.5:1 or between about 0.75:1 and 2.25:1. The SFR ratio is calculated by determining the amount of sand added to an estimated amount of solid fines in the tailings on a weight basis.
It is believed that the use of coarse particles facilitates packing of the consolidated fines which advantageously increases the solids content and can even form a jammed structure of consolidated solids, i.e. a structure in which generally individual particles of the consolidated solid can no longer move freely relative to other particles.

[0052] Treating bitumen froth tailings with at least one highly water soluble salt and optionally with either or both of at least one polymer flocculant and/or sand can be carried out in a number of ways. In certain embodiments, treating the bitumen froth tailings includes combining and/or mixing the various components. In addition, the at least one salt can be added directly to the tailings either as an undiluted powder or as a solution; the at least one polymer flocculant can be added directly to the tailings either as an undiluted material or as a solution, and the sand can be added to the tailings directly or with the salt and/or polymer or solutions thereof. The salt and polymer can be combined in a single solution, with or without sand, and combined with the tailings. The order of combining the salt, polymer and sand to the tailings can give equivalent results and optimization of the process will depend on the scale and equipment used in the process.
DM_US 153846401-2 098351 0041

[0053] However, it tends to be more convenient to first prepare one or more solutions including the one or more highly water soluble salt(s) and the one or more polymer flocculant(s) followed by combining the one or more solutions with the bitumen froth tailings and sand. In certain embodiments, an aqueous solution of one or more highly water soluble salt(s) can be prepared having a concentration of no less than about 0.5 wt% or 1 wt%, e.g., at least about 2 wt%, 3 wt%, 4 wt%, 5 wt%, 6 wt%, 7 wt%, 10 wt%, 20 wt%, 30 wt% and even as great as a 40 wt% or as an aqueous salt slurry for use in treating the tailings. The one or more polymer flocculant(s) can also be included in the aqueous solution of the salt(s) and can have a concentration of no less than zero and up to about 0.001 wt%, e.g., up to about 0.003 wt%, 0.005 wt%, 0.01 wt%, 0.04 wt%, 0.05 wt %, 0.1 wt%, 0.2 wt%, 0.4 wt%, for example.
The aqueous solution of the highly water soluble salt(s) and polymer flocculant(s) can be used to treat the bitumen froth tailings and can be combined with such tailings at a ratio of between 5.0:1.0 and 1.0:5.0, such as 3: to 1:3 and at a ratio between 1.5:1.0 to 1.0:1.5 of bitumen froth tailings to aqueous solution. Sand can be combined with the tailings before, during, or after combining the tailings with the salt(s) and polymer(s) solutions.

[0054] Because highly water soluble salts and polymer flocculants that are preferably water soluble are used in the process of the present disclosure, the temperature of the treated tailings need not be elevated above ambient to practice the process. In certain embodiments, treating the bitumen froth tailings according to the various embodiments herein can be carried out at a temperature of no more than 50 C, e.g., no more than about 40 C or 30 C.
Advantageously, the processes of the present disclosure can be practiced without addition of a significant amount of an alkali metal hydroxide salt(s), such as lithium, sodium or potassium hydroxide, e.g., less than 0.05 wt% or without any addition of such salts.
Such strongly alkali salts tend to require elevated temperatures to be effective.

[0055] In practicing aspects of the present disclosure, bitumen froth tailings, e.g., a suspension of particulate solids in an aqueous liquid which include fines and process water, can be consolidated by treating the bitumen froth tailings with at least one highly water soluble salt or aqueous solutions thereof and can optionally include either or both of (i) at least one polymer flocculant, e.g., a water soluble flocculating polymer, or aqueous solutions thereof, and/or (ii) coarse particles, e.g., sand to form a treated tailings. Treating tailings in this manner can cause DM_US 153846401-2 098351 0041 destabilization and consolidation of the solids, e.g., fines and sand, in the treated tailings to form a consolidated material, which can settle under gravity relatively quickly, in the process water.
The process water can then be readily separated from the consolidated material.

[0056] The treated tailings and/or consolidated material can be further dewatered to further separate the process water from the consolidated material and, in some instances, further consolidate the solids. In some embodiments, the consolidated material formed in the treated tailings can be separated from the process water by any one or more of decanting, filtering, e.g., electrofiltering, cross-flow filtering, gravity draining, vacuuming and other evaporating techniques, etc. or combinations thereof and/or by any one or more of a mechanical dewatering, i.e., applying an external force to the consolidated material, with a device for dewatering consolidated material such as by applying a centrifuge, decanting centrifuge, dewatering screw, hydrocyclone, filter press, pressing device, etc. or combinations thereof. In one aspect of the processes of the present disclosure, the process water can be separated from the consolidated material by passing a stream of treated tailings through a cross-flow filter, e.g., a porous or slotted pipe, which filters and dewaters the treated tailings stream to separate the process water from the consolidated material. In another aspect of the processes of the present disclosure, the process water can be separated from the consolidated material by gravity draining to achieve a solids content of at least about 70% within about a month after treating the tailings, e.g., within about two weeks or within about one week of gravity draining after treating the tailings.

[0057] The consolidated material formed in the treated tailings can advantageously have a high solids content, e.g., a solids content of greater than about 50% and at least about 60%, 65%, 70% and 75% by weight. In addition, the consolidated material formed in the treated tailings according to certain embodiments can result in a high solids content after mixing and/or dewatering the treated tailings in a short period. In embodiments of the present disclosure, the consolidated material can have a solids content of greater than about 50% and at least about 60%, 65%, 70%, 75% and 80% by weight after mixing and/or dewatering. In certain embodiments a solids content of at least about 70 % is achieved within about one month of gravity draining after treating the tailings, e.g., within about two weeks or within about one week of gravity draining after treating the tailings.
DM_US 153846401-2 098351 0041

[0058] In an embodiment of the present disclosure, the process includes mixing the bitumen froth tailings with a highly water soluble salt, e.g., an ammonium based salt, a water soluble polymer, e.g., a polyacrylamide, and sand, e.g., in a sand to fines ratio of between 0.75:1 and 2.25:1 to form a treated tailings including a consolidated material having a high solids content, e.g., a solids content of greater than about 50% by weight, e.g., at least about 60%, 65%, 70 wt% or higher.

[0059] Another advantage of the processes of the present disclosure is the recovery of materials from tailings that include rare earth elements. For example, certain tailings can include valuable minerals that include rare earth elements. A rare earth element (REE), as defined by IUPAC, is one of a set of seventeen chemical elements in the periodic table, specifically the fifteen lanthanides, as well as scandium and yttrium. Scandium and yttrium are considered rare earth elements because they tend to occur in the same ore deposits as the lanthanides and exhibit similar chemical properties. Many of the REE are used in electronic devices, magnets, high performance coatings. Such REE include cerium (Ce), dysprosium (Dy), erbium (Er), europium (Eu), gadolinium (Gd), holmium (Ho), lanthanum (La), lutetium (Lu), neodymium (Nd), praseodymium (Pr), promethium (Pm), samarium (Sm), scandium (Sc), terbium (Tb), thulium (Tm), ytterbium (Yb) and yttrium (Y).

[0060] REE in aqueous fines are typically in the form of an ion or oxide.
For example, zirconium can be present as zircon, ZrSiO4, titanium can be present as the minerals ilmenite, leucoxene and rutile. Coal ash and coal cleaning wastes contain rare earth elements. Fire clay coal ash has unusually high concentrations of Yttrium and zirconium. Oil sands tailings also contain REE.

[0061] The processes of the present disclosure are useful in recovering REE. It is believed that in some tailings, REEs absorb on the surface of clays in tailings. In other tailings, REEs are included also among the solids of the tailings but can also be in the process water.
Absorbed REEs can be exchanged with the highly water soluble salts of the present disclosure, e.g., ammonium based salts due to an exchange of ammonium ions for the REE
ions. REEs from the solids of the tailings can be obtained by leaching the solids with acid followed by extraction and precipitation or by caustic decomposition followed by acid leaching.
DM_US 153846401-2 098351 0041

[0062] Another aspect of processes of the present disclosure includes consolidating an aqueous composition including fines and process water, e.g., tailings, which include REE
materials by treating the composition with at least one highly water soluble salt, e.g., an ammonium based salt such as ammonium sulfate, to form a treated composition including a consolidated material in process water which includes the REE materials in the process water and/or among the consolidated materials. In one aspect of the present disclosure, the treated composition consolidates the fines and also separates REE materials from the solids and into the process water. The process water can then be separated from the consolidated material and the REE materials can be recovered from the separated process water. The REE
materials can be recovered from the process water by precipitation, e.g., using oxalic acid, or extraction. Other methods for recovering REE from the process water include mineral processing and physical beneficiation, deep eutectic solvents/ionic liquids extraction, acid dissolution, high temperature phase separations, use of REE selective sorbents, photophoresis, in-situ brine injection and extraction, reactive grinding, etc. In other aspect of the present disclosure, the treated composition consolidates the fines and REEs are among the consolidated materials. The process water can then be separated from the consolidated material. The consolidated material can then be leached with acid, e.g., nitric acid, sulfuric acid, etc., followed by extraction with solvent and/or ion exchange resins and precipitated. Alternatively, the consolidated material can then be treated with a caustic reagent such as sodium hydroxide to decompose certain of the materials to form hydroxides of the REEs followed by leaching in acid, e.g., HC1.

[0063] The process of the present disclosure allows for large scale treatment of bitumen froth tailings in a continuous or semi-continuous process with further recovering, recycling and purifying at least a portion of the process water in the tailings. When non-hydrolyzing, highly water soluble salts are used in the processes of the present disclosure, the process water separated from an initial treated tailings can advantageously include a significant amount of the one or more highly water soluble salt(s) initially used to treat the tailings.

[0064] In practicing aspects of the processes of the present disclosure and the various embodiments thereof, the separated process water can include the at least one highly water soluble salt and the process can further comprise one or more of: (i) recovering at least a portion of the separated process water; (ii) recycling at least a portion of recovered separated process DM_US 153846401-2 098351 0041 water to treat additional bitumen froth tailings; and/or (iii) purifying at least a portion of recovered process water. In some implementations, the recovered separated process water, which includes the highly soluble salts(s), can be processed to concentrate the highly soluble salts(s) in the water. For example, a reserve osmosis system, which generates desalted water and a waste brine, can be used to generate a brine which includes the highly soluble salts(s) from recovered, separated process water from the treated bitumen froth tailings. This brine can then be used to treat additional bitumen froth tailings and the process can be carried out in a continuous or semi-continuous manner.

[0065] Figure 1 schematically illustrates such an exemplary continuous or semi-continuous process. As shown in the figure, bitumen froth tailings is treated with one or more highly water soluble salt(s) by combining a stream of the salt(s) (101a), which can be as an aqueous solution, with a stream of tailings (103a). Optionally, the tailings can also be treated with one or more polymer flocculant(s) by combining a stream of the flocculants(s) (102a), which can be as an aqueous solution, with the tailings stream (103a).
Alternatively, the salts(s) and flocculant(s) can be combined together as a solution to treat the tailings as a stream thereof.
Coarse particles (sand) can also be added to the bitumen froth tailings or stream thereof and/or to any or all of the solution streams.

[0066] The streams of salt(s) and polymer(s) can be sourced from holding areas 101 and 102 and the streams of tailings and sand can be sourced from holding areas 103 and 105, respectively. Alternatively, the froth tailings and/or the stream of sand can be sourced directly from an oil sands extraction or separation operation.

[0067] For this embodiment, the stream of salt(s) (101a) and polymer(s) (102a) and tailings stream (103a) are carried to mixing device 107. (Optionally, a stream of sand can be added to the streams of salt(s) and polymer(s) (105a) or to tailings stream (105b), for example).
Mixing device 107 can be an inline mixer, a mixing tank, ribbon mixer or other mixing device that can mix streams 101a, 102a, 103a and 105a. For this embodiment, the bitumen froth tailings are combined with the salt(s) and polymer(s) as solutions followed by addition of sand to treat the tailings. However, the bitumen froth tailings can be treated with an aqueous solution including both the salt(s) and polymer(s. In addition, the order can be changed, e.g., the sand can be combined with the bitumen froth tailings (105b) followed by mixing with the salt(s) and DM_US 153846401-2 098351 0041 polymer(s) solution or solutions. The sand can be added as a wet or dry stream. In some embodiments, the combination of the streams in a line can cause sufficient mixing to eliminate the need for a separate mixing device, e.g., inline mixing, and the combined streams can be carried directly to a mechanical dewatering device to separate consolidated material from process water.

[0068]
As shown in the embodiment of Figure 1, after mixer 107, the treated tailings, which include a consolidated material and process water, is transferred to a solids/liquid separator 109, e.g., dewatering device, to separate the process water from the consolidated material.
Such devices include, for example, one or more of a decanting, filtering, electrofiltering, cross-flow filtering, gravity draining, or vacuuming device or combination thereof and/or by one or more of a device for dewatering consolidated material such as a centrifuge, decanting centrifuge, dewatering screw, hydrocyclone, vacuum belt filter, filter press or pressing devices, etc. or combinations thereof.

[0069]
A stream of separated process water (111) can be recovered and collected in a tank or pond and a stream of separated consolidated material (113) can be recovered. For this embodiment, the recovered process water (111) includes the process water from the tailings and from stream 101a and thus includes residual salt(s) from the one or more highly water soluble salt(s) and can possibly include residual polymer(s) from the one or more polymer flocculant(s.
There are also highly water soluble salts that are constituents of the original tailings and these become part of the recovered process water. In some embodiments, the recovered process water (111) can then be transferred to a water purifying system 115 to purify at least a portion of the recovered process water (117) which can be used for other operations or discharged. Water purifying systems that can be used for embodiments of the processes of the present disclosure include reverse osmosis systems, vacuum distillation systems, electrodialysis, filtration systems, etc. The remaining, non-purified recovered process water, which includes the one or more highly water soluble salt(s) from stream 101a and potentially highly water soluble salt(s) that are constituents of the original tailings (119) can be recycled back to the treatment process. For this embodiment, at least a portion of the non-purified recovered process water can be recycled back to holding tank 101 and deficiency in the concentration of the salt(s) or polymer(s) can be DM_US 153846401-2 098351 0041 corrected by adding additional highly water soluble salt(s) or polymer flocculant(s) from one or more make-up tanks such as make-up tanks 121 and 122.

[0070] In certain implementations of the process of the present disclosure, at least a portion, if not all, of recovered process water stream 111 can be recovered and purified with a reverse osmosis system. Such a system can concentrate the at least one highly soluble salt in the recovered portion of separated process water 111 to form a brine. At least a portion, if not all, of the brine can be cycled back to salt / polymer flocculant storage 101 and/or 102 to treat additional tailings. Such a reverse osmosis system can concentrate the at least one highly soluble salt to a concentration of greater than about 2 wt% such as greater than about 4 wt%, 5 wt%, 6 wt%, 7wt% and higher such that the salt-tailings concentration in salt /polymer flocculant storage containers can be at an equilibrium of about 2wt% to about 7 wt%, and values therebetween, or higher. Thus, the salt concentration of the highly water soluble salt in storage 101 can be maintained at a range of about 2 wt % to about 7 wt%, and values therebetween, depending on the amount of process water subject to reverse osmosis system and cycled back to the process.
The aqueous solution stream including the at least one highly water soluble salt and the at least one polymer flocculant can be combined with the tailings stream 103a at a ratio within a range of about 5.0:1.0 to about 1.0:5.0, e.g., combined at a ratio within a range of about 3:1 to about 1:3, such as about 1.5:1.0 to about 1.0:1.5.

[0071] The process of the present disclosure can also include steps to recover residual hydrocarbon, e.g., tar, crude oil, heavy oil, or other hydrocarbon oil, bitumen, asphaltenes, etc.
from the bitumen froth tailings. As explained earlier, bitumen froth tailings typically include a low amount of residual bitumen. The bitumen froth tailings can also include residual asphaltenes depending on the oil sands extraction process as well as other hydrocarbons, such as tar, crude oil, heavy oil, or other hydrocarbon oil, etc. and/or diluents or solvents from the oil sands extraction operation.

[0072] The process of the present disclosure can further include adding an organic diluent to the bitumen froth tailings to dilute hydrocarbon therein and to promote separation and recovery of the hydrocarbon. Organic diluents useful for the processes of the present disclosure are soluble or mix readily with the hydrocarbon but are immiscible with water.
Organic diluents useful for the processes of the present disclosure aid in diluting the hydrocarbon separated from the composition to reduce the viscosity thereof. Such organic diluents include, for example, aromatic hydrocarbons such as benzene, toluene, xylene, non-aromatic hydrocarbons such as pentanes, hexanes, cyclohexane, heptanes, mixtures of hydrocarbons such as naphtha, e.g., light or heavy naphtha, kerosene and paraffinic diluents, etc. Hydrocarbon separated from the treated tailings can then be recovered by any number of processes useful for recovering hydrocarbon separated from solids and an aqueous mixture such as by skimming, decanting, distilling, centrifuging, etc. using such devices such as decanters, distillation columns, pressure separators, centrifuges, open tank, hydrocyclones, settling chambers or other separators, etc.

[0073] It is believed that when a polymer flocculant is used to treat the tailings, the polymer acts in concert with the salt(s) to sequester solids, particularly fines, and to minimize emulsion formation in the treated composition. The organic diluent(s) aid in separating the hydrocarbon and lowers the viscosity of viscous hydrocarbons separated from the composition, which aids in recovering the hydrocarbons. Advantageously, the hydrocarbon separated from the tailings can contain a low amount of fines or has low minerals content, e.g., less than about 1 wt% or no more than about 0.5 wt% or no more than about 0.1 wt%. The determination of fines content can be assessed by detecting for mineral matter content in the separated hydrocarbon by infrared spectroscopy, x-ray diffraction, ash content or by an equivalent method.

[0074] In addition, the consolidated solids can be recovered. The recovered consolidated solids can include residual highly water soluble salt(s) from the treatment of the tailings. When the salt used in treating the tailings is beneficial to plant life, such as an ammonium based salt or sulfate based salt or phosphate based salt, the residual salt can act as a fertilizer with the consolidated solids.

[0075] EXAMPLES

[0076] The following examples are intended to further illustrate certain preferred embodiments of the invention and are not limiting in nature. Those skilled in the art will recognize, or be able to ascertain, using no more than routine experimentation, numerous equivalents to the specific substances and procedures described herein.

[0077] Bitumen Froth Tailings

[0078] A portion of a bitumen froth tailings (FT) sample obtained from an oil sands extraction operation was poured into a glass jar and the picture shown in Figure 2A taken a few DM_US 153846401-2 098351 0041 minutes later. There was a degree of settling and some sand was visible at the bottom of the jar.
The fines remained suspended. A sample of the stirred and remixed material was taken and its solids content determined to be 12.6% by drying in a vacuum oven.

[0079] Treatment of Bitumen Froth Tailings With Highly Water Soluble Salt and Polymer Flocculant

[0080] In an initial consolidation experiment, equal weights of a 5%
ammonium sulfate solution containing 0.1% polyacrylamide (PAM) and froth tailings were mixed in a vial then centrifuged at 3000 rpm for 30 secs, to accelerate settling. The result is shown in Figure 2B. It can be seen that the solids consolidate to give a bottom layer in contact with an apparently clear supernatant. It appears that there is a layer of black material at the surface of the clear water, but this is simply a reflection of the bottom mineral layer in the meniscus.

[0081] The supernatant liquid was removed with a pipette and the solids content of the consolidated material was determined to be 38.7% by drying.

[0082] Treatment of Bitumen Froth Tailings With Highly Water Soluble Salt and Polymer Flocculant and Sand

[0083] Additional treatment of froth tailings samples with a salt solution, polymer and sand were performed in two additional ways. First, sand was added to a froth tailings sample to give a solids ratio (sand to froth tailings solids) of 1:1. Salt (ammonium sulfate) and polymer (polyacrylamide) were then added as solids and the mixture stirred. The amount of salt and polymer added gave a salt concentration of 2.5% and a polymer concentration of 0.05%, respectively, in the final mixture. The vial was then centrifuged at 3000 rpm for 30 secs, to accelerate settling. The result is shown in the vial on the left in Figure 3.
The result obtained with the addition of an equal weight of the 5% ammonium sulfate solution containing 0.1%
polyacrylamide polymer to the froth tailings/sand mixture is shown in the right-hand vial. A
consolidated material was obtained using both methods.

[0084] The solids content of the consolidated material at the bottom of the froth tailings/solution vial (right hand vial in Figure 3) was determined to be 53.9%.

[0085] Treatment of Bitumen Froth Tailings With Highly Water Soluble Salt and Polymer Flocculant and Sand and Diluent DM_US 153846401-2 098351 0041

[0086] A further set of experiments involved the simultaneous removal of residual hydrocarbon from the froth tailings, principally bitumen, using a diluent. The results are shown in Figure 4. The vial on the left was obtained by mixing froth tailings with an equal weight of a 5% ammonium sulfate solution containing 0.1% polyacrylamide (PAM) and some naphtha. No sand was used. The vial on the right included sand, with the proportion of sand to froth tailings (FT) solids being 1:1. Without sand, the hydrocarbon layer appeared to contain some emulsified clays/hydrocarbons. The material obtained using sand appeared much cleaner.
This was confirmed using infrared spectroscopy.

[0087] Only the preferred embodiment of the present invention and examples of its versatility are shown and described in the present disclosure. It is to be understood that the present invention is capable of use in various other combinations and environments and is capable of changes or modifications within the scope of the inventive concept as expressed herein. Thus, for example, those skilled in the art will recognize, or be able to ascertain, using no more than routine experimentation, numerous equivalents to the specific substances, procedures and arrangements described herein. Such equivalents are considered to be within the scope of this invention, and are covered by the following claims.
DM_US 153846401-2 098351 0041

Claims (34)

WHAT IS CLAIMED IS:

1. A process for consolidating bitumen froth tailings which include fines and process water, the process comprising:
treating the bitumen froth tailings with at least one highly water soluble salt to form a treated tailings including a consolidated material in the process water; and separating the process water from the consolidated material.

2. A process of consolidating bitumen froth tailings which include fines and process water, the process comprising:
treating the bitumen froth tailings with at least one highly water soluble salt and at least one polymer flocculant to form a treated tailings including a consolidated material in the process water; and separating the process water from the consolidated material.

3. A process of consolidating bitumen froth tailings which include fines and process water, the process comprising:
treating the bitumen froth tailings with at least one highly water soluble salt and coarse particles to form a treated tailings including a consolidated material in the process water; and separating the process water from the consolidated material.

4. A process of consolidating bitumen froth tailings which include fines and process water, the process comprising:
treating the bitumen froth tailings with at least one highly water soluble salt, at least one polymer flocculant and coarse particles to form a treated tailings including a consolidated material in the process water; and separating the process water from the consolidated material.

5. The process of any one of claims 1-4, wherein the bitumen froth tailings further comprise hydrocarbon and the process further comprises treating the bitumen froth tailings with a diluent to dilute the hydrocarbon and recovering the diluted hydrocarbon.

6. The process of claim 5, wherein the hydrocarbon comprises bitumen or asphaltenes or a combination thereof.

7. The process of any one of claims 5-6, wherein the recovered diluted hydrocarbon has less than 1 wt% of fines.

8. The process of any one of claims 1-7, wherein the at least one highly water soluble salt has a solubility in water of greater than 10 g/100 g at 20 °C

9. The process of any one of claims 1-4, wherein the at least one highly water soluble salt has a monovalent cation.

10. The process of any one of claims 1-9, wherein the treated tailings has a salt-tailings concentration of the at least one highly water soluble salt of at least 0.5 wt%.

11. The process of any one of claims 1-11, wherein the at least one highly water soluble salt is an ammonium based salt.

12. The process of claim 11, wherein the ammonium based salt is selected from ammonium chloride, ammonium bromide, ammonium carbonate, ammonium bicarbonate, ammonium nitrate, ammonium sulfate, ammonium phosphate, or a combination thereof.

13. The process of any one of claims 2 or 4-12, wherein the at least one polymer flocculant is a polyacrylamide or co-polymer thereof.

14. The process of any one of claims 2 or 4-13, wherein the treated tailings have a polymer-tailings concentration of the at least one polymer flocculant of no less than about 0.04 wt%.

15. The process of any one of claims 1 or 3-12, wherein the tailings are treated with sand at a sand to fines ratio between 2.5:1.0 to 0.5:1.

16. The process of any one of claims 1-12, wherein treating the tailings includes combining the bitumen froth tailings with a stream of an aqueous solution including the at least one highly water soluble salt to produce a treated tailings stream.

17. The process of any one of claims 2 or 4-13, wherein treating the tailings includes combining the bitumen froth tailings with a solution including the at least one highly water soluble salt and the at least one polymer flocculant to produce a treated tailings stream.

18. The process of any one of claims 2 or 4-13, wherein treating the tailings includes combining the bitumen froth tailings with a stream of an aqueous solution including the at least one highly water soluble salt and a stream of an aqueous solution including the at least one polymer flocculant to produce a treated tailings stream.

19. The process of any one of claims 3-13, wherein treating the tailings includes combining the bitumen froth tailings with a stream of an aqueous solution including the at least one highly water soluble salt and a stream of an aqueous solution including the at least one polymer flocculant and adding sand to the tailings and/or to at least one of the streams to produce a treated tailings stream.

20. The process of any one of claims 16-19, wherein the streams are mixed in line and optionally with an inline mixer to produce the treated tailings stream.

21. The process of any one of claims 16-20, wherein the treated tailings stream is passed through a cross-flow filter to separate the process water from the consolidated material.

22. The process of any one of claims 1-20, comprising separating the process water from the consolidated material by any one or more of decanting, filtering, vacuuming, gravity draining, electrofiltering, or combinations thereof.

23 The process of any one of claims 1-20, wherein separating the process water from the consolidated material includes mechanically dewatering the consolidated material.

24. The process of any one of claims 1-20, wherein separating the process water from the consolidated material includes gravity draining.

25. The process of any one of claims 1-24, wherein the consolidated material has a solids content of at least 45% by weight.

26. The process of any one of claims 1-25, further comprising recovering at least a portion of the separated process water and subjecting a portion of the recovered separated process water to reverse osmosis to form a brine which includes the at least one highly soluble salt and using the brine to treat additional bitumen froth tailings.

27. The process of claim 26, further comprising recycling at least a portion of the recovered separated process water to treat additional bitumen froth tailings.

28. The process of any one of claims 26-27, further comprising purifying at least a portion of the recovered process water.

29. The process of any one of claims 1-28, wherein the tailings are treated at a temperature of less than 50 °C.

30. A process for consolidating bitumen froth tailings which include hydrocarbon, fines and process water, the process comprising:

treating the bitumen froth tailings with at least one highly water soluble salt to form a treated tailings including a consolidated material in the process water; and separating the hydrocarbon from the process water and the consolidated material.

31. The process of claim 30, further comprising treating the bitumen froth tailings with a diluent to dilute the hydrocarbon and recovering the diluted hydrocarbon.

32. The process of any one of claims 30-31, wherein the recovered diluted hydrocarbon has less than 1 wt% of fines.

33. The process of any one of claims 30-32, further comprising recovering at least a portion of the separated process water and subjecting a portion of the recovered separated process water to reverse osmosis to form a brine including the at least one highly soluble salt and using the brine to treat additional bitumen froth tailings.

34. The consolidated material obtained from any one of claims 1-33.