CA2863487C - Methods for processing an oil sand slurry or a bitumen extract stream - Google Patents

Abstract

A method may include providing a bitumen extract stream, having bitumen dissolved in a first solvent, and suspended fines; separating the bitumen extract stream into a concentrated fines stream and a low fines bitumen extract stream; producing agglomerated fines by agglomerating the concentrated fines stream; forming washed agglomerated fines by washing the agglomerated fines with a washing solvent that removes residual bitumen extract from the agglomerated fines; producing dry solids by removing the washed solvent from the washed agglomerated fines; and producing a bitumen product stream by removing the first solvent from the low fines bitumen extract stream.

Description

METHODS FOR PROCESSING AN OIL SAND SLURRY OR A BITUMEN
EXTRACT STREAM
BACKGROUND
Field of Disclosure [00011 The disclosure relates generally to the field of oil sand processing. More specifically, the disclosure relates to methods for processing an oil sand slurry or a bitumen extract stream.
Description of Related Art

[0002] This section is intended to introduce various aspects of the art, which may be associated with the present disclosure. This discussion is believed to assist in providing a framework to facilitate a better understanding of particular aspects of the present disclosure.
Accordingly, it should be understood that this section should be read in this light, and not necessarily as admissions of prior art.
[00031 Modern society is greatly dependent on the use of hydrocarbon resources for fuels and chemical feedstocks. Hydrocarbons are generally found in subsurface formations that can be termed "reservoirs." Removing hydrocarbons from the reservoirs depends on numerous physical properties of the subsurface formations, such as the permeability of the rock containing the hydrocarbons, the ability of the hydrocarbons to flow through the subsurface formations, and the proportion of hydrocarbons present, among other things.
Easily harvested sources of hydrocarbons are dwindling, leaving less accessible sources to satisfy future energy needs. As the costs of hydrocarbons increase, the less accessible sources become more economically attractive.
100041 Recently, the harvesting of oil sand to remove heavy oil has become more economical. Flydrocarbon removal from oil sand may be performed by several techniques.
For example, a well can be drilled to an oil sand reservoir and steam, hot air, solvents, or a combination thereof, can be injected to release the hydrocarbons. The released hydrocarbons may be collected by wells and brought to the surface. In another technique, strip or surface mining may be performed to access the oil sand, which can be treated with hot water, steam or solvents to extract the heavy oil. This other technique may be referred to as a water-based extraction process (WBE). The WBE is a commonly used process to extract bitumen from mined oil sand. In another technique, a non-water-based extraction process can be used to treat the strip or surface mined oil sand. The non-water-based extraction process may be referred to as a solvent-based recovery process. The commercial application of a solvent-based recovery process has, for various reasons, eluded the oil sand industry. A major challenge associated with the solvent based extraction process is the tendency of fine particles within the oil sand to hamper the separation of solids from the heavy oil (e.g., bitumen) extracted. The fine particles that remain with the bitumen have an adverse impact on the transport of the bitumen within pipelines and have a negative impact on the downstream upgrading and/or refining of the bitumen. For these reasons, it is desirable to reduce the solids content of the bitumen to a value much less than 1 weight (wt.) %.
Another major challenge to the application of a solvent-based recovery process for oil sand is the recovery of solvent from the bitumen-free solids. This solvent-based recovery process is often energy intensive and limits the economics of the overall solvent-based process.
[0005] One proposed method for handling the challenges of fine solids in a solvent-based recovery process is to classify the oil sand slurry into a coarse stream having coarse solids and a fines stream having fines solids, as described in U.S.
Patent No. 4,071,433 (Hanson 1). Handling the challenges of fine solids in a solvent-based recovery process may be referred to as solid classification. Thc fines stream may be referred to as a fines solids stream; the coarse stream may be referred to as a coarse solids stream. Hanson 1 describes a process where the oil sand slurry is separated into two streams, one comprising the majority of the coarse solids and the other comprising the majority of the fines solids. The fines stream is directed to a coker to yield coke and a hydrocarbon vapor stream. The coarse stream is filtered and then washed with kerosene. The filtrate from the filtration process and the hydrocarbon vapor stream from the coker are directed to a fractionator. The fractionator produces gas and oil fractions, which are recovered as products. The process handles the fines solids by having them act as the nuclei in the coke forming reaction.
The fines solids are then removed when the coke is discharged from the coker. Using a coker to handle the fines solids, however, has the disadvantages of lowering the liquid yield of the bitumen extraction process and results in liquid products that require hydrogen stabilization.
The disadvantageous outcomes are particularly undesirable at production facilities.
[0006] Another example of solid classification in a solvent-based recovery process is described in U.S. Patent No. 4,139,450 (Hanson 2). Hanson 2 describes a process where the oil sand slurry is separated into two phases ¨ a fines stream having fine solids and a coarse stream having coarse solids. Bitumen extract is removed from the coarse solids by filtration.
Two centrifuging steps are used to recover the bitumen extract from the fine solids. The first centrifuge is used to separate the majority of the fine solids from the bitumen extract. Prior to the second centrifuge, fine solids from the first centrifuge are mixed with fresh solvent. The mixture is then centrifuged in the second centrifuge to recover a lean bitumen extract stream.
The solids from the second centrifuge are finally mixed with water and then undergoes steam stripping to recover residual solvent. The process in Hanson 2 has the disadvantage of requiring multiple stages of fine solids dispersion and concentration. The process in Hanson 2 also has the disadvantage of producing a fine tailings stream that will require a tailings pond for long term storage.
[0007] Another example of solid classification in a solvent-based recovery process is the process described in CA 1,169,002 (Karnofsky). Karnofsky describes a process where an oil sand slurry is separated into a coarse solids stream and a fines solids stream by gravity separation. Bitumen extract is removed from the coarse solids stream by using a series of percolating beds. Bitumen extract is removed from the fines solids stream by using a complicated system of clarifiers, thickeners, and filters. The process in Karnofsky has the disadvantage that solid-liquid scparation of the fines solids stream remains a challenge.
[0008] Another example of solid classification in a solvent-based recovery process is a solvent extraction with solids agglomeration process. The solid agglomeration process was coined Solvent Extraction Spherical Agglomeration (SESA). Previously described methodologies for SESA have not been commercially adopted. In general, the SESA process

- 3 -=
involves mixing oil sand with a hydrocarbon solvent to form an oil sand slurry, adding an aqueous bridging liquid to the oil sand slurry to form a mixture, agitating the mixture in a slow and controlled manner to nucleate particles, and continuing such agitation so as to permit these nucleated particles to form larger multi-particle spherical agglomerates for removal.
The aqueous bridging liquid may be water or an aqueous solution since the solids of oil sand are mostly hydrophilic and water is immiscible to hydrocarbon solvents. The aqueous bridging liquid preferentially wets the solids. With the right amount of the aqueous bridging liquid and suitable agitation of the slurry; the aqueous bridging liquid displaces the suspension liquid on the surface of the solids. As a result of interfacial forces among three phases (i.e.
the aqueous bridging liquid, the suspension liquid, and the solids), fine particles within the solids consolidate into larger, compact agglomerates that are more readily separated from the suspension liquid.
[0009] The SESA process described by Meadus et al. in U.S. Patent No.

4,057,486 involves combining solvent extraction with solids agglomeration to achieve dry tailings suitable for direct mine refill. Organic material is separated from oil sand by mixing the oil sand material with an organic solvent to form a slurry, after which an aqueous bridging liquid is added in an amount of 8 to 50 weight percent (wt.%) of the feed mixture. By using controlled agitation, solid particles from oil sand come into contact with the aqueous bridging liquid and adhere to each other to form macro-agglomerates with a mean diameter of 2 millimeters (mm) or greater. The macro-agglomerates are more easily separated from the organic solvent compared to un-agglomerated solids. The macro-agglomerates are referred to as macro-agglomerates because they result from the consolidation of both fine particles and coarse particles that make up oil sand.
[0010] U.S. Patent No. 4,719,008 (Sparks et al.) describes a process to apply SESA to varying ore grade qualities by a micro-agglomeration procedure in which the fine particles of the oil sand are consolidated to produce micro-agglomerates with a similar particle size distribution to coarser grained particles of the oil sand. Using the micro-agglomeration procedure, the solid-liquid separation behavior of the agglomerated oil sand will be similar regardless of ore grade quality. The micro-agglomeration procedure occurs within a slowly rotating horizontal vessel. The conditions of the slowly rotating horizontal vessel arc that which favor the formation of large agglomerates; however, a light milling action is used to continuously break down the micro-agglomerates. The micro-agglomerates are formed by obtaining an eventual equilibrium between cohesive and destructive forces.
Since micro-agglomerates of large size can lead to bitumen recovery losses owing to entrapment of extracted bitumen within the agglomerated solids, the levels of bridging liquid is kept to as low as possible commensurate with achieving economically viable solid-liquid separations.
[0011] With the formation of the micro-agglomerates, the process of solid-liquid separation using common separation devices is easier compared to the situation where the fine particles (i.e., fine solids) are not agglomerated. Applicable separation devices include at least one of gravity separators, centrifuges, hydrocyclones, screens, and filters. Although the separation devices have been shown to be effective in separating micro-agglomerates from bitumen extract, a portion of the fine solids remain un-agglomerated because they are non-wetting with the aqueous bridging liquid and thus remain as residual fine solids in the bitumen extract. The amount of the residual fine solids that remain in the bitumen extract can be greater than 1 wt. % on a dry bitumen basis. Wt. % on a dry bitumen basis means ignoring water in the bitumen extract for the purpose of calculation. "Dry bitumen basis" means ignoring the presence of water in the bitumen extract for the purpose of calculating wt.%.
[0012] Solvent deasphalting has previously been proposed as a method to remove the residual fine solids that remain from the bitumen extract. U.S. Patent No.
4,572,777 (Peck) describes a process where non-dissolved asphaltenes are used to remove the fine solids within the bitumen extract. The bitumen extract may comprise a solvent mixture where at least one solvent has a solubility parameter higher than bitumen and at least one solvent with a solubility parameter lower than bitumen. The non-dissolved asphaltenes may result from removing the higher solubility parameter solvent from the bitumen extract so that a fraction of the asphaltenes will precipitate and aggregate with the fine solids. The precipitated asphaltenes and fine solids can then be readily separated from the bitumen extract.

- 5 -[0013] The addition of chemical additives to the bitumen extract has been proposed as a method to remove fines from the bitumen extract. U.S. Patent No. 4,229,281 (Alquist et al.) describes a process where the bitumen extract is mixed with water comprising a cationic surfactant to form a mixture. The mixture settles into a low fine bitumen extract layer, an interface layer where the fine solids collect, and an aqueous layer. Solvent can be removed from the low fine bitumen extract layer to produce a low-ash bitumen product.
The water in the aqueous layer can be recycled and mixed with makeup water and surfactant.
The interface layer, which comprises the fine solids and residual bitumen, can be disposed of as waste or undergo further treatment in an attempt to recover water and the residual bitumen.
[0014] U.S. Patent No. 4,888,108 (Farnand) describes a process where an aliphatic solvent, such as pentane, is added along with a chemical additive to the bitumen extract. The addition of the aliphatic solvent causes asphaltenes to precipitate onto the residual fine solids.
The combination of the precipitated asphaltenes and the chemical additive causes the residual fine solids to aggregate so that they can by readily separated from the bitumen extract.
Farnand describes that the most effective chemical additives are water-soluble organic compounds with a low miscibility with the bitumen extract. The organic compounds preferably comprise a carboxylic acid and/or hydroxyl groups, and have a weakly acidic and/or polar character. The chemical additives, such as resorcinol, catechol, formic acid, and maleic acid, have a synergistic effect with the addition of the aliphatic solvent. Less additive and aliphatic solvent was needed, when used in combination, to obtain the same level of solids removal as compared to when the additive or aliphatic solvent was used alone. Farnand theorized that the improved residual fine solids aggregation was due to the precipitated asphaltenes increased attraction to the residual fine solids with the polar additives adsorbed onto the residual fine solids surfaces.
[0015] Another method for removing the residual fine solids that remain in the bitumen extract is to use aliphatic solvents for the extraction of bitumen from oil sand. U.S.
Patent Publication 2011/0127197 (Blackboum et al.) describes the use of a C3 to C9 paraffinic solvent for extracting bitumen from oil sand. The use of paraffinic solvent, such as pentane, prevents all or a portion of the asphaltenes within the bitumen from dissolving into

- 6 -solution during the solvent-based recovery process. Since the asphaltenes tend to be associated with fine solids, the asphaltenes that do not dissolve prevent the fine solids from dispersing into the bitumen extract. Blackboum et al. described that the use of the paraffinic solvent improved the separation of bitumen extract by filtration. The increased filtration rate, compared to when an aromatic solvent was used for bitumen extraction, was most likely due to the fact that some of the fine solids remained attached to the solid asphaltenes and thus were not free to block the filter media or the solid bed on top of the filter media. The use of paraffinic solvent in the solvent-based recovery process resulted in faster settling fine solids that could be readily separated from the majority of the bitumen extract by gravity to producc a bitumen extract with fine solids content of less than 0.1 wt.% on a dry bitumen basis.
[0016] The processes described above are for handling fines within the solvent based-recovery process. For example, the oil sand slurry can be classified into a fines strcam and a coarse stream to improve solid-liquid separation of the fines stream in the oil sand slurry from the coarse stream. Asphaltcne precipitation and/or chemical additives can be used to help separate out the fines stream from the bitumen extract. However, after the fines stream is separated out from the bitumen extract, there remains a need to develop an effective method for removing residual bitumen and solvent from the fines without re-dispersing the fines stream in an oil sand slurry or a bitumen extract stream.
SUMMARY
[0017] It is an object of the present disclosure to provide methods for processing an oil sand slurry or a bitumen extract stream.
[0018] A method may comprise: a) providing a bitumen extract stream, comprising bitumen dissolved in a first solvent, and suspended fines; b) separating the bitumen extract stream into a concentrated fines stream and a low fines bitumen extract stream; c) producing agglomerated fines by agglomerating the concentrated fines stream; d) forming washed agglomerated fines by washing the agglomerated fines with a washing solvent that removes residual bitumen extract from the agglomerated fines; e) producing dry solids by removing the

- 7 -washing solvent from the washed agglomerated fines; and 0 producing a bitumen product stream by removing the first solvent from thc low fines bitumen extract stream.
[0019] The foregoing has broadly outlined the features of the present disclosure so that the detailed description that follows may be better understood.
Additional features will also be described herein.
BRIEF DESCRIPTION OF THE DRAWINGS
[0020] These and other features, aspects and advantages of the disclosure will become apparent from the following description, appending claims and the accompanying drawings, which are briefly described below.
[0021] Figure 1 is a graph of the resulting permeability of a bed of agglomerates.
[00221 Figure 2 is a flow chart of a method for processing a bitumen extract stream.
[0023] Figure 3 is a flow chart of a method for processing an oil sand slurry.
[0024] Figure 4 is a flow chart of a method for processing an oil sand slurry.
100251 Figure 5 is a flow chart of a method for processing an oil sand slurry.
100261 It should be noted that the figures are merely examples and no limitations on the scope of the present disclosure are intended thereby. Further, the figures are generally not drawn to scale, but are drafted for purposes of convenience and clarity in illustrating various aspects of the disclosure.
DETAILED DESCRIPTION
[0027] For the purpose of promoting an understanding of the principles of the disclosure, reference will now be made to the features illustrated in the drawings and specific language will be used to describe the same. It will nevertheless be understood that no limitation of the scope of the disclosure is thereby intended. Any alterations and further modifications, and any further applications of the principles of the disclosure as described herein are contemplated as would normally occur to one skilled in the art to which the

- 8 disclosure relates. It will be apparent to those skilled in the relevant art that some features that are not relevant to the present disclosure may not be shown in the drawings for the sake of clarity.
[0028] At the outset, for ease of reference, certain terms used in this application and their meaning as used in this context are set forth below. To the extent a term used herein is not defined below, it should be given the broadest definition persons in the pertinent art have given that term as reflected in at least one printed publication or issued patent. Further, the present processes are not limited by the usage of the terms shown below, as all equivalents, synonyms, new developments and terms or processes that serve the same or a similar purpose are considered to be within the scope of the present disclosure.
[0029] Throughout this disclosure, where a range is used, any number between or inclusive of the range is implied.
[0030] A "hydrocarbon" is an organic compound that primarily includes the elements of hydrogen and carbon, although nitrogen, sulfur, oxygen, metals, or any number of other elements may be present in small amounts. Hydrocarbons generally refer to components found in heavy oil or in oil sand. However, the techniques described are not limited to heavy oils but may also be used with any number of other reservoirs to improve gravity drainage of liquids. Hydrocarbon compounds may be aliphatic or aromatic, and may be straight chained, branched, or partially or fully cyclic.
[0031] "Bitumen" is a naturally occurring heavy oil material. Generally, it is the hydrocarbon component found in oil sand. Bitumen can vary in composition depending upon the degree of loss of more volatile components. It can vary from a very viscous, tar-like, semi-solid material to solid forms. The hydrocarbon types found in bitumen can include aliphatics, aromatics, resins, and asphaltenes. A typical bitumen might be composed of:
19 weight (wt.) % aliphatics (which can range from 5 wt. % - 30 wt. %, or higher);
19 wt. % asphaltenes (which can range from 5 wt. % - 30 wt. %, or higher);
30 wt. % aromatics (which can range from 15 wt. % - 50 wt. %, or higher);

- 9 -32 wt. % resins (which can range from 15 wt. % - 50 wt. %, or higher); and some amount of sulfur (which can range in excess of 7 wt. %).
In addition, bitumen can contain some water and nitrogen compounds ranging from less than 0.4 wt. % to in excess 010.7 wt. %. The percentage of the hydrocarbon found in bitumen can vary. The term "heavy oil" includes bitumen as well as lighter materials that may be found in a sand or carbonate reservoir.
[00321 "Heavy oil" includes oils which are classified by the American Petroleum Institute ("API"), as heavy oils, extra heavy oils, or bitumens. The term "heavy oil" includes bitumen. Heavy oil may have a viscosity of about 1,000 centipoise (cP) or more, 10,000 cP or more, 100,000 cP or more, or 1,000,000 cP or more. In general, a heavy oil has an API
gravity between 22.3 API (density of 920 kilograms per meter cubed (kg/m3) or 0.920 grams per centimeter cubed (g/cm3)) and 10.0 API (density of 1,000 kg/m3 or 1 g/cm3). An extra heavy oil, in general, has an API gravity of less than 10.0 API (density greater than 1,000 kg/m3 or 1 g/cm3). For example, a source of heavy oil includes oil sand or bituminous sand, which is a combination of clay, sand, water and bitumen. The recovery of heavy oils is based on the viscosity decrease of fluids with increasing temperature or solvent concentration. Once the viscosity is reduced, the mobilization of fluid by steam, hot water flooding, or gravity is possible. The reduced viscosity makes the drainage or dissolution quicker and therefore directly contributes to the recovery rate.
100331 The term "bituminous feed" refers to a stream derived from oil sand that requires downstream processing in order to realize valuable bitumen products or fractions.
The bituminous feed is one that comprises bitumen along with undesirable components.
Undesirable components may include but are not limited to clay, minerals, coal, debris and water. The bituminous feed may be derived directly from oil sand, and may be, for example, raw oil sand ore. Further, the bituminous feed may be a feed that has already realized some initial processing but nevertheless requires further processing. Also, recycled streams that comprise bitumen in combination with other components for removal as described herein can be included in the bituminous feed. A bituminous feed need not be derived directly from oil sand, but may arise from other processes. For example, a waste product from other extraction

- 10-processes which comprises bitumen that would otherwise not have been recovered may be used as a bituminous feed.
100341 "Fine particles" are generally defined as those solids having a size of less than 44 microns (l.im), that is, material that passes through a 325 mesh (44 micron).
[0035] "Coarse particles" are generally defined as those solids having a size of greater than 44 microns ( m).
[0036] A "solvent-based recovery process" or "solvent extraction process"
or "oil sands solvent extraction process" includes any type of hydrocarbon recovery process that uses a solvent, at least in part, to enhance the recovery, for example, by diluting or lowering a viscosity of the hydrocarbon. Solvent-based recovery processes may be used in combination with other recovery processes, such as, for example, thermal recovery processes. In solvent-based recovery processes, a solvent is injected into a subterranean reservoir. The solvent may be heated or unheated prior to injection, may be a vapor or liquid and may be injected with or without steam. Solvent-based recovery processes may include, but are not limited to, solvent assisted cyclic steam stimulation (SA-CSS), solvent assisted steam assisted gravity drainage (SA-SAGD), solvent assisted steam flood (SA-SF), vapor extraction process (VAPEX), heated vapor extraction process (H-VAPEX), cyclic solvent process (CSP), heated cyclic solvent process (H-CSP), solvent flooding, heated solvent flooding, liquid extraction process, heated liquid extraction process, solvent-based extraction recovery process (SEP), thermal solvent-based extraction recovery processes (TSEP), and any other such recovery process employing solvents either alone or in combination with steam. A
solvent-based recovery process may be a TSEP if the solvent is heated prior to injection into the subterranean reservoir. The solvent-based recovery process may employ gravity drainage.
[0037] "Macro-agglomeration" is the consolidation of both fine particles and coarse particles that make up the oil sand. Macro-agglomerates may have a mean diameter of 2 millimeters (mm) or greater.

- 11 -=

[0038] "Micro-agglomeration" is the consolidation of fine particles that make up the oil sand. Micro-agglomerates may have a mean diameter of less than 2 millimeters (mm).
[0039] A "bitumen extract stream" is generally defined as a stream comprising bitumen dissolved in a solvent, and also comprising suspended fines. The bitumen extract stream may have a solids content of less than 30 wt. %, or less than 20 wt. %.
[0040] A "low fines bitumen extract stream" is generally defined as a bitumen extract stream having a low solids content, such as less than 0.5 wt. %, or less than 0.1 wt. %, on a dry bitumen basis.
[0041] A "concentrated fines stream" is generally defined as a fines stream having a high solids content, such as greater than 30 wt. %, or greater than 40 wt. %.
[0042] A "bitumen product stream" is generally defined as a bitumen product that may be suitable for transport within pipelines and processing within downstream refineries.
The bitumen product stream may have a solids content of less than 0.5 wt.%, or less than 0.1 wt. %, on a dry bitumen basis.
[0043] The terms "approximately," "about," "substantially," and similar terms are intended to have a broad meaning in harmony with the common and accepted usage by those of ordinary skill in the art to which the subject matter of this disclosure pertains. It should be understood by those of skill in the art who review this disclosure that these terms are intended to allow a description of certain features described and claimed without restricting the scope of these features to the precise numeral ranges provided. Accordingly, these terms should be interpreted as indicating that insubstantial or inconsequential modifications or alterations of the subject matter described and are considered to be within the scope of the disclosure.
[0044] The articles "the", "a" and "an" are not necessarily limited to mean only one, but rather are inclusive and open ended so as to include, optionally, multiple such elements.
[0045] "At least one," in reference to a list of one or more entities should be understood to mean at least one entity selected from any one or more of the entity in the list of

- 12-entities, but not necessarily including at least one of each and every entity specifically listed within the list of entities and not excluding any combinations of entities in the list of entities.
This definition also allows that entities may optionally be present other than the entities specifically identified within the list of entities to which the phrase "at least one" refers, whether related or unrelated to those entities specifically identified. Thus, as a non-limiting example, "at least one of A and B" (or, equivalently, "at least one of A or B," or, equivalently "at least one of A and/or B") may refer, to at least one, optionally including more than one, A, with no B present (and optionally including entities other than B); to at least one, optionally including more than one, B, with no A present (and optionally including entities other than A); to at least one, optionally including more than one, A, and at least one, optionally including more than one, B (and optionally including other entities). In other words, the phrases "at least one," "one or more," and "and/or" are open-ended expressions that are both conjunctive and disjunctive in operation. For example, each of the expressions "at least one of A, B and C," "at least one of A, B, or C," "one or morc of A, B, and C,"
"one or more of A, B, or C" and "A, B, and/or C" may mean A alone, B alone, C alone, A and B
together, A and C together, B and C together, A, B and C together, and optionally any of the above in combination with at least one other entity.
[0046] Effective agglomeration of solids may require a solids concentration within an oil sand slurry of greater than 30 wt. %, or greater than 40 wt. %. Figure 1 shows a significant reduction in the bed permeability of agglomerates as the concentration of an oil sand slurry is reduced. The bitumen extract stream may have a solids concentrations of less than 30 wt. %, or more likely less than 20 wt. Vo, which is lower than a solids concentration indicative of effective agglomeration of solids. It may be desirable to concentrate the fine solids to produce an oil sand slurry more suitable for solids agglomeration, thereby allowing for effective agglomeration of solids. The fine solids that have been concentrated may be referred to as concentrated fines. The concentrated fines may be agglomerated by agitating the solids in a mixing tank, a rotating vessel, or within a pipeline. A
bridging liquid may be added to the concentrated fines to assist in the agglomeration process. The concentrated fines

- 13 -may be mixed with additional solids prior to agglomeration. For example, the concentrated fines may be mixed with an oil sand slurry prior to agglomeration.
[0047] The methods described in the present disclosure may be combined with aspects of other solvent-based recovery processes, including but not limited to solvent extraction with a solids agglomeration process. The solvent extraction process need not be solvent extraction with a solids agglomeration process. Non-limiting examples of solvent-based recovery processes that are solvent extraction with solids agglomeration processes, include those described in the background of the present disclosure and in CA 2,724,806 ("Adeyinka et al.").
[0048] Adeyinka et al. discloses extracting bitumen from oil sands in a manner that employs solvent. A solvent is combined with a bituminous feed derived from oil sand to form an initial slurry. The initial slurry is separated into a fines solids stream and a coarse solids stream, where the majority of the fine solids within the oil sand are in the fine solids stream and the majority of the coarse solids within oil sand are in the coarse solids stream. The coarse solids steam can be separated into coarse solids and a first low solids bitumen extract stream. Aqueous bridging liquid is added to the fine solids stream to agglomerate the fine solids in the stream and form an agglomerated slurry. The agglomerated slurry can be separated into agglomerates and a second low solids bitumen extract stream. A
second solvent can be mixed with the low solids bitumen extract streams to form a solvent-bitumen low solids mixture, which can then be separated further into low grade and high grade bitumen extracts. Recovery of solvent from the low grade and high grade extracts is conducted to produce bitumen products of commercial value.
[0049] A method and system for processing a bitumen extract stream (202) may be depicted in Figures 2 and 5. The method and system may comprise providing the bitumen extract stream (202), (502). The bitumen extract stream (202) may comprise bitumen dissolved in a first solvent. The bitumen extract stream (202) may comprise suspended fines.
[0050] The method and system may comprise separating the bitumen extract stream (202) into a concentrated fines stream (208) and a low fines bitumen extract stream (206),

- 14 -(504). The bitumen extraction stream (202) may be separated in a separator (204). The bitumen extract within the bitumen extract stream (202) may be separated from fines within the bitumen extract stream (202) to produce the low fines bitumen extract stream (206) and the concentrated fines stream (208). The concentrated fines stream (208) may have a solids content of greater than 30 wt. %, or greater than 40 wt. %. The separator (204) may comprise any suitable separator. For example, the separator (204) may comprise gravity separation or an enhanced gravity process. Other examples of a separator (204) include, but are not limited to, clarifiers, thickeners, centrifuges, and cyclonic devices.
[00511 Separating the bitumen extract stream (202) can be assisted by precipitating asphaltenes and/or by adding additives to help aggregate the fines in the bitumen extract stream (202) into larger particles that can be more readily separated from the bitumen extract.
The precipitated asphaltenes and the fines may be separated from a weight majority of the bitumen.
[0052] The low fines bitumen extract stream (206) may have a solids content of less than 0.5 wt. %, or less than 0.1 wt. %, on a dry bitumen basis. Achieving this level of solids content in the low fines bitumen extract stream (206) may require the removal of the oleophilic fines that are in a stable suspension with the bitumen extract stream (202). The removal of these olcophilic fines can be assisted by precipitating asphaltenes and/or by adding additives to help aggregate the fines in the bitumen extract stream (202) into larger particles that can be more readily separated from the bitumen extract stream (202).
Asphaltene precipitation can be induced by at least one of adding or removing solvent from the bitumen extract stream (202), changing the temperature of the bitumen extract stream (202), and changing the pressure of the bitumen extract stream (202). The solvent may be referred to as a second solvent. One way to induce asphaltene precipitation is to add a paraffinic solvent, such as but not limited to pentane, to the bitumen extract stream (202).
Applicable additives that can be used to help aggregate the fines in the bitumen extract stream (202) include chemical additives, such as surfactants, flocculants, and coagulants. The chemical additive can be water soluble where an aqueous solution of the chemical additive is mixed with the bitumen extract stream (202). The chemical additive can be miscible with the bitumen extract

- 15 -stream (202). The chemical additive can be directly miscible in the hydrocarbon phase.
Other classes of applicable additives that may be suitable include solid additives. Examples of solid additives include, but are not limited to, clays, molecular sieves, activated carbon, and carbon black. The solid additives, which may be much larger particles than the fines in the bitumen extract stream, may absorb and/or adsorb the fines in the bitumen extract stream prior to being separated from the bitumen extract stream.
100531 The bitumen within the bitumen extract stream may remain in the low fines bitumen extract stream (206). For example, when the additive added to assist in separating the bitumen extract stream into the concentrated fines stream (208) and the low fines bitumen extract stream (206) from the fines is a water soluble additive, the water soluble additive makes the bitumen extract stream remain the dominant phase in the low fines bitumen extract stream as compared to the fines.
[0054] While not shown in Figure 2, the first solvent can be removed from the low fines bitumen extract stream (206) to produce a bitumen product strcam (222), (512). Other solvent may also be removed from the low fines bitumen extract stream (206) to produce the bitumen product stream (222). The bitumcn product stream (222) may be suitable for transport within pipelines and processing within downstream refineries. The bitumen product stream (222) may have a solids content of less than 0.5 wt. %, or less than 0.1 wt. %.
100551 The method and system may comprise producing agglomerated fines (212) by agglomerating the concentrated fines stream (208), (506). The concentrated fines stream (208) may be agglomerated in an agglomeration process (210). The agglomerated fines (212) may be produced after the concentrated fines stream (208) exits the separator (204) to enter the agglomeration process (210).
[0056] Agglomerating the concentrated fines stream (208) may comprise adding a bridging liquid to the concentrated fines stream (208). The bridging liquid may assist in agglomerating the concentrated fines stream (208). The bridging liquid may be an aqueous liquid. The bridging liquid may include additional additives, referred to as agglomerating assistive additives, to ensure agglomeration of the oleophilie fines within the concentrated

- 16-CA 02863487 2014-09-1.1 fines stream (208). The bridging liquid is a liquid with an affinity for solids particles in the concentrated fines stream (208). The bridging liquid may be immiscible in the first solvent.
Exemplary aqueous liquids may be recycled water from other aspects or steps of oil sands processing. The aqueous liquid need not be pure water, and may be water containing one or more salts, a waste product from conventional aqueous oil sand extraction processes which may include additives, aqueous solution with a range of pH, or any other acceptable aqueous solution capable of adhering to solid particles in such a way that permits fines to adhere to each other.
[00571 The agglomeration process (210) may be assisted by some form of agitation.
The form of agitation may be mixing, shaking, rolling, or another known suitable method.
The agitation of the concentrated fines stream (208) need only be severe enough and of sufficient duration to intimately contact the bridging liquid with the solids in the concentrated fines stream (208). Exemplary rolling type vessels include rod mills and tumblers.
Exemplary mixing type vessels include mixing tanks, blenders, and attrition scrubbers. In the case of mixing type vessels, a sufficient amount of agitation may be needed to keep the agglomerated fines (212) in suspension. In rolling type vessels, the solids content of the concentrated fines stream (208) may be greater than 40 wt. % so that compaction forces assist agglomerated fines (212). The agitation of a slurry has an impact on the growth of the agglomerated fines (212). In the case of mixing type vessels, the mixing power can be increased in order to limit the growth of agglomerates by attrition of said agglomerates. In the case of rolling type vessels, the fill volume and rotation rate of the vessel can be adjusted in order to increase the compaction forces used in the communition of agglomerated fines (212).
[0058] Before agglomerating the concentrated fines stream (208), the concentrated fines stream (208) may be mixed with additional solids. For example, the concentrated fines stream (208) may be mixed with an additional agglomerated solids and/or an oil sand slurry prior to agglomerating the concentrated fines stream (208). The larger sand particles that are within an oil sand slurry may provide additional surface for the concentrated fines stream (208) to agglomerate.

- 17 -[0059] The method and system may comprise forming washed agglomerated fines (218) by washing the agglomerated fines (212), (508). The agglomerated fines (212) may be washed in a washing process (214). The washed agglomerated fines (218) may be formed after the agglomerated fines (212) exit the agglomerator process (210) to enter the washing process (214). The agglomerated fines (212) may be washed in the washing process (214) with a washing solvent (216). The agglomerated fines (212) may be washed in the washing process (214) with the washing solvent (216) with the aid of a filter. The filter may assist in removing residual bitumen extract from the agglomerated fines (212) to form the washed agglomerated fines (218). The washed agglomerated fines (218) may be placed directly on the filter. The agglomerated fines (212) may be washed counter-currently with the washing solvent (216). The filter may comprise a drying portion where the agglomerated fines are dried. The drying portion may minimize the content of washing solvent within the washed agglomerated fines (218) prior to drying within a tailings solvent recovery unit. The filter may comprise a drainage portion upstream of a washing portion. The drainage portion may be for draining liquid from the filter. The washing portion may be for washing the agglomerated fines with the washing solvent. The washed agglomerated fines (218) may be mixed with additional agglomerated solids (for instance from an agglomerated oil sand slurry) prior to being filtered by the filter.
[0060] The method and system may comprise producing dry solids (222) by removing the washing solvent (220) from the washed agglomerated fines stream (218), (510). Other solvent, such as but not limited to the first solvent, may also be removed from the washed agglomerated fines stream (218) while producing the dry solids (222). The dry solids (222) may be produced in a tailings solvent recovery unit (227). The dry solids (222) may be produced after the washed agglomerated fines stream (218) exits the washing process (214) to enter the tailings solvent recovery unit (227). The dry solids (222) may have a solvent content of less than 0.5 wt. %. The dry solids (222) may have a liquid content of less than 15 wt. cYD.
The first solvent in the bitumen extraction stream (202) and the washing solvent (216) may be the same or different.

- 18-100611 The tailings solvent recovery unit (227) may use direct and/or indirect heat to evaporate the washing solvent (216) from the washed agglomerated fines stream (218). The tailings solvent recovery unit (227) may impose a vacuum to remove solvent vapor.
"Vacuum" as used herein simply means a pressure gradient causing a suction.
The tailings solvent recovery unit (227) may impose a gas flow current to remove dry solids solvent vapor.
The tailings solvent recovery unit (227) may comprise tailings solvent recovery units. Once drying of the dry solids (222) is complete, the dry solids (222) can be sent to disposal.
[00621 The agglomerated fines (212) may be drained and washed in a low oxygen gas-tight filtration unit. The low oxygen gas-tight filtration unit may be any suitable unit, such as but not limited to a vacuum belt or a vacuum and/or pressure pan filter. The agglomerated fines (212) may be washed in a counter-current manner with progressively cleaner solvent.
For example, four separate washing stages with progressively cleaner solvent may be employed as the agglomerated fines (212) progresses along the vacuum belt. The counter-current washing of the agglomerated fines (212) allows for the efficient use of the washing solvent. In the final stage of the low oxygen gas-tight filtration unit, the agglomerated fines (212) may be dried by flowing gas through the agglomerated fines (212). The resulting washed agglomerated fines (218) may be in the form of a filter cake, which may be relatively free of bitumen and have a moisture content of less than 15 wt.%, may go to further solvent removal steps before discarding as dry solids (222) with low residual solvent content that meets or exceeds environmental requirements.
[0063] Removing fines from a bitumen extract stream (202) in the manner depicted in Figures 2 and 5 and described above with respect to Figures 2 and 5 may have the advantage of providing an effective method for recovering residual bitumen extract from the agglomerated fines without re-dispersing the agglomerated fines (212) in a fluid. For example, the residual bitumen extract can be recovered by counter-current washing of the agglomerated fines (212) by using a filter. Residual bitumen extract means bitumen extract in the concentrated fines stream (208) after being separated from the low fines bitumen extract stream. The residual bitumen extract is bitumen cxtract that remains in the agglomerated fines (212). Recovering the residual bitumen extract by filtration may be more efficient than

-19-multiple stages of fluid washing and concentrating of the agglomerated fines (212) in vessels.
The agglomerated fines (212) can be dried to a solvent content of less than 5 wt. % during thc drying stage of the filter. The initial drying of the agglomerated fines (212) within the filter may reduce the required load on the tailings solvent recovery unit (227).
100641 The solvent extraction with solid agglomeration process described by Adeyinka et al. is one suitable solvent extraction process for the processes described with respect to Figures 2 and 5. As mentioned above, the effective agglomeration of the agglomerated fines may require a solids concentration within the slurry of greater than 30 wt.
%, or greater than 40 wt. %. The fines stream described by Adeyinka et al. may have a solids concentration much less than 30 wt. %. For this reason, the fines stream may be concentrated as described in the present disclosure prior to agglomeration of the agglomerated fines. The fines are concentrated by separating the majority of the bitumen extract from the fines.
[00651 The solvent extraction process may involve removal and recovery of solvent used in the process. In this way, solvent is used and re-used, even when a good deal of bitumen is entrained within the solvent. Because an exemplary solvent to bitumen ratio of the bitumen extract may be 2:1 or lower, it is acceptable to use recycled solvent containing bitumen as the extraction liquor to achieve this ratio. Make-up solvent is used to account for solvent losses and may form part of the bitumen extract stream (202), the oil sand slurry (302 or 402), the washing solvent (216), or solvent used in the washing steps (318 or 420). The amount of make-up solvent may depend solely on solvent losses, as there is no requirement to store and/or not re-use solvent that has been used in a previous step within the process. When solvent is said to be "removed", or "recovered", this does not require removal or recovery of all solvent, as it is understood that some solvent will be retained with the bitumen even when the majority of the solvent is removed.
[0066] The methods and systems disclosed may contain a single solvent recovery unit for recovering the solvent(s) arising from the bitumen extract stream. The methods and systems disclosed may contain more than one solvent recovery unit. Solvent may be recovered by conventional means. For example, typical solvent recovery units may comprise

- 20 -a fractionation tower or a distillation unit. The solvent recovered in this fashion will not contain bitumen entrained in the solvent. The recovered solvent may be referred to as clean solvent. The clean solvent may be used as the washing solvent in the washing of solids in order that the cleanest wash of the solids is conducted using the cleanest solvent.
[0067I The solvent recovered from the solvent recovery unit may comprise entrained bitumen. The solvent recovered may be re-used as the extraction liquor for combining with the bituminous feed. The solvent may have bitumen entrained within the solvent, for example, in countercurrent washing of solids. Additional solvent may be added to a solvent having bitumen entrained to achieve a desired solvent to bitumen ratio.
[0068] Figure 3 is a flow chart of a method and system for processing an oil sand slurry (302). The method and system shown in Figure 3 may comprise providing an oil sand slurry (302). The oil sand slurry (302) may be provided by combining a bituminous feed (not shown) and an extraction liquor (not shown). The oil sand slurry (302) may comprise a bitumen extract and solids. The oil sand slurry (302) may have a solid content in the range of to 70 wt.%, 20 to 70 wt.%, or 40 to 70 wt.%. In the case of a solvent extraction with solids agglomeration process, a higher solids content oil sand slurry may be desired since that may increase the compaction forces that may help in an agglomeration process. In other cases, a lower solids content may be desired in order to reduce the mixing energy needed in a solvent-based extraction process. A lower solids content oil sand slurry may be desired for solid-liquid separation. The oil sand slurry may have a higher solids content for the solvent-based extraction process and the agglomeration process; the oil sand slurry may be diluted to a lower solids content prior to solid-liquid separation.
[0069] The temperature of the oil sand slurry (302) may be in the range of 20-100 C.
When the oil sand slurry has a temperature within the aforementioned range, the temperature of the oil sand slurry may be referred to as an elevated temperature. The temperature may be within this range to increase the bitumen dissolution rate. The temperature may be within this range to reduce the viscosity of the oil sand slurry, thereby promoting more effective sand digestion and agglomerate formation. An elevated slurry temperature may be desired to

-21 -improve the solid-liquid separation process. Higher temperatures results in a reduced slurry viscosity, which in turn, may improve solid-liquid separation. Temperatures above 100 C are generally avoided due to the complications resulting from high vapor pressures.
[00701 The extraction liquor may comprise a first solvent used to extract bitumen from the bituminous feed in the oil sand slurry (302). The term "solvent" as used herein should be understood to mean either a single solvent, or a combination of solvents. The extraction liquor may comprise a hydrocarbon solvent capable of dissolving the bitumen. The extraction liquor may be a solution of a hydrocarbon solvent(s) and bitumen, where the bitumen content of the extraction liquor may range between 0 and 70 wt.%, or between 0 and 50 wt.%. to the extraction liquor may contain dissolved bitumen. When the extraction liquor contains dissolved bitumen, the volume of the extraction liquor may be increased without an increase in the required inventory of hydrocarbon solvent(s).
[00711 The solvent extraction process may be adjusted to provide a ratio of solvent to bitumen in the oil sands slurry that minimizes asphaltenes precipitation during bitumen extraction. The presence of some amount of precipitated asphaltenes is unavoidable. By adjusting the amount of solvent flowing into bitumen extraction, one can control a ratio of solvent to bitumen in an extraction vessel. Bitumen in the extraction vessel comes from the bituminous feed and any bitumen entrained in the extraction liquor. Selecting the ratio of bitumen to solvent may decrease the costs for processing the bituminous feed if the ratio is one with less solvent than bitumen. Having less solvent than bitumen may lower the costs for processing the bituminous feed because of the lower solvent requirements.
[0072] The ratio of solvent to bitumen may be selected as a target ratio.
The target ratio may be less than 2:1. For example but not limited to, the target ratio may be 1.5:1 or less, 1:1 or less, or 0.75:1. For clarity, ratios may be expressed in the present disclosure using a colon between two values, such as "2:1", or may equally be expressed as a single number, such as "2", which carries the assumption that the denominator of the ratio is 1 and is expressed on a weight to weight basis.

- 22 -[0073] The extraction liquor may be recycled from a downstream step. For instance, solvent recovered in a solvent recovery unit may be used to wash solids, and the resulting lean bitumen extract stream may be used as the extraction liquor. The residual bitumen within the extraction liquor may increases the volume of the extraction liquor. The residual bitumen within the extraction liquor may increase the solubility of the extraction liquor for additional bitumen dissolution.
[0074] Several types of solvents are suitable for use in the solvent extraction process.
The solvent may be a light aromatic solvent with zcro to 100% aromatic compounds.
Exemplary solvents include, but are not limited to, benzene, toluene, naphtha and kerosene.
In cases where the aromatic content of the solvent is less than what is needed to fully dissolve the bitumen in the bituminous feed, pre-dissolved bitumen within the extraction liquor can increase the solubility of the extraction liquor towards dissolving additional bitumen.
[0075] The solvent may comprise at least one of an open chain aliphatic hydrocarbon, and a cyclic aliphatic hydrocarbon. For example, low boiling point cycloalkanes, or mixture of such cycloalkanes, can substantially dissolve asphaltencs.
[0076] The solvent may comprise a paraffinic solvent in which the solvent to bitumen ratio of the bitumen extract and/or the first extraction liquor is maintained at a level to avoid or limit precipitation of asphaltenes. The paraffinic solvent may comprise at least one of an alkane, a natural gas condensate, and a distillate from a fractionation unit (or diluent cut) containing more than 40% small chain paraffins of 3 to 10 carbon atoms, referred to herein as a small chain (or short chain) paraffin mixture.
[0077] Should an alkane be selected as the solvent, the alkane may comprise at least one of a normal alkane and an iso-alkane. The alkane may comprise at least one of heptane, iso-heptane, hexane, iso-hexane, pentane, and iso-pentane.
[0078] A cyclic aliphatic hydrocarbon may be selected as the solvent, it may comprise a cycloalkane of 4 to 9 carbon atoms. A mixture of C3-C9 cyclic and/or open chain aliphatic solvents may be appropriate. Exemplary cycloalkanes include at least one of cyclohexane and

- 23 -cyclopentane. If the solvent is selected as the distillate from a fractionation unit, it may for example be one having a final boiling point of less than 180 C. An exemplary upper limit of the final boiling point of the distillate may be less than I00 C. A mixture of C3-C10 cyclic and/or open chain aliphatic solvents would also be appropriate. For example, it can be a mixture of C3-C9 cyclic aliphatic hydrocarbons and paraffinic solvents where the percentage of the cyclic aliphatic hydrocarbons in the mixture is greater than 50%.
[0079] The solvent may have a final boiling point of less than 200 C
(degrees Celsius). The solvent may have a final boiling point of less than 100 C. While it is not necessary to use a solvent having a final boiling point of less than 200 C or less than 100 C , there may be an extra advantage that solvent recovery proceeds at lower temperatures, and requires a lower energy consumption.
[0080J The method and system shown in Figure 3 may comprise forming an agglomerated slurry (306) by agglomerating solids in the oil sand slurry (302) in an agglomeration process (31'7). Agglomerating the oil sand slurry (302) may comprise adding a bridging liquid (304) to the oil sand slurry (302) to agglomerate the solids in the oil sand slurry as agglomerated solids.
[0081] The agglomerated solids within the agglomerated slurry (306) may be sized on the order of 0.1-1.0 mm, on the order of 0.1-0.5 mm or on the order of 0.1-0.3 mm. At least 80 wt. % of the agglomerated solids may be 0.1-1.0 mm, on the order of 0.1-0.5 mm or 0.1 to 0.3 mm in size. The rate of agglomeration may be controlled by a balance between intensity of agitation within an agglomeration vessel, shear within the agglomeration vessel which can be adjusted, for example, by changing the shape or size of the agglomeration vessel, fincs content of the slurry, bridging liquid addition, and residence time of the agglomeration process (317). The agglomerated slurry (306) may have a solids content of 20 to 70 wt. %.
100821 The bridging liquid (304) is described above with reference to Figure 2. The bridging liquid may be added to the oil sand slurry (302) in a concentration of less than 20 wt.
% of the slurry, less than 10 wt. % of the slurry, between 1 wt. % and 20 wt.
%, or between 1 wt. % and 10 wt. %. The bridging liquid (304) may comprise fine particles (for instance less

- 24 -than 44 um) suspended therein. The fine particles may serve as seed particles for the agglomeration process (317). The bridging liquid (304) may comprise less than 40 wt.% solid fines, or of 20 to 70 wt. % solid fines.
[0083] The agglomeration process (317) may be assisted by some form of agitation as described above with reference to Figure 2.
[0084] The method and system shown in Figure 3 may comprise forming a bitumen extract stream (308) by separating bitumen extract from agglomerated solids in the agglomerated slurry (306). The bitumen extract stream (308) may be formed within a washing step (318). The bitumen extract stream (308) comprises bitumen extract and suspended fines.
[0085] The method and system depicted in Figure 3 may comprise aggregating fines in the bitumen extract stream (308) by adding an aqueous solution (310) of an additive. The bitumen extract stream may be separated from the aggregated fines in a separator (312) to produce a low fines bitumen extract stream (314) and a concentrated fines stream (316). The separator (312) may comprise any suitable separator as described above with reference to Figure 2. At least a portion of the concentrated fines stream (316) may be recycled so that it is used as the bridging liquid (304) described above for mixing with at least a portion of the oil sand slurry (302).
[0086] Separating the bitumen extract stream (308) into a concentrated fines stream (308) and a low fines bitumen extract stream (314) may result in the production of three layers: a low fines bitumen extract layer, an aqueous layer, and an interface layer. The interface layer may be between the low fines bitumen extract layer and the aqueous layer.
The bitumen extract layer may be free of a weight majority of the fines and have a solids content of less than 0.5 wt. %, or less than 0.1 wt. %. The aqueous layer comprises primarily water. The aqueous layer may be reused. The interface layer comprises the concentrated fines, which may be a concentrated fines stream. The interface layer may have water as a continuous phase. The interface layer may have less than 5 wt. % bitumen extract. All or some of the interface layer may be used as the bridging liquid in the agglomeration process

- 25 -described in step (b). Using the interface layer as the bridging liquid has the potential advantage of reducing the amount of the concentrated fines stream (316) that would have to be sent to tailings ponds, by allowing the fines to be captured in the agglomerated solids.
Using the interface layer as the bridging liquid has the potential advantage of allowing for the recovery of the bitumen that is within the interface layer.
[0087] Separating the bitumen extract stream (308) into a concentrated fines stream (308) and a low fines bitumen extract stream (314) may result in the production of two layers:
a low fines bitumen extract layer and an aqueous layer. The bitumen extract layer may be free of a weight majority of the fines and have a solids content of less than 0.5 wt. %, or less than 0.1 wt. %. The aqueous layer may comprise a fines stream. The aqueous layer may have water as a continuous phase. The aqueous layer may be the concentrated fines stream. The aqueous layer may have less than 5 wt. % bitumen extract. Some or all of the aqueous layer may be used as the bridging liquid in the agglomeration process described in step (b). The aqueous layer may be processed to further concentrate the fine solids, for instance by separating fine solids within the aqueous layer from a weight majority of water to produce a dewatered concentrated fines stream having water as a continuous phase. The dewatered concentrated fines stream may be used as the bridging liquid (304). Using the aqueous layer or a portion of the aqueous layer as the bridging liquid has the potential advantage of reducing the amount of the concentrated fines stream (316) that would have to be sent to tailing ponds, by allowing the fines to be captured in the agglomerated solids.
[0088] The method and system shown in Figure 3 may comprise washing the agglomerated solids with a washing solvent in the washing step (318) to remove residual bitumen extract from the agglomerated fines. Washing solvent may be removed from the washed agglomerated solids (320) to produce dry solids (322) using a tailings solvent recovery unit (327) as described above with reference to Figure 2.
[0089] Figure 4 is a flow chart of a method and system for processing an oil sand slurry (402). The method and system shown in Figure 4 may comprise providing n oil sand slurry (402). The oil sand slurry (402) may be provided by combining a bituminous feed (not

-26-shown) and an extraction liquor (not shown). The oil sand slurry (402) may comprise a bitumen extract and solids.
[00901 The method and system shown in Figure 4 may comprise separating the oil sand slurry (402) in a separator (404) into a bitumen extract stream (406) and a coarse solids stream (408). The separator (410) may be any suitable separator as described above with reference to Figure 2. The majority (by weight) of the fines within the oil sand slurry (402) are in the bitumen extract stream (406) and the majority (by weight) of the coarse solids within the oil sand slurry (402) are in the coarse solids stream (408). The method and system may comprise separating the fines from the bitumen extract stream (406) in another separator (410) to produce a low fines bitumen extract stream (412) and a concentrated fines stream (414). The separator (410) may be any suitable separator as described above with reference to Figure 2.
[00911 The separation process occurring in separation (410) may be assisted by precipitating asphaltcnes and/or by adding additives to help aggregate the fines into larger particles that can be more readily separated from the bitumen extract, as described above with reference to Figure 2. The method and system shown in Figure 4 may comprise agglomerating the concentrated fines stream (414) in an agglomerator (416) to produce agglomerated fines (418).
[0092] The method and system in Figure 4 may comprise forming washed agglomerated fines (422) by washing the agglomerated fines (418) with a washing solvent in a washing step (420) to remove residual bitumen extract from the agglomerated fines.
[0093] The method and system shown in Figure 4 may comprise producing dry solids (424) by removing the washing solvent from the washed agglomerated fines (422).
[0094] The bitumen extract may remain the continuous phase of the concentrated fines stream (414). For example, whcn a watcr soluble additive is used to assist fine solid separation, the bitumen extract remains the dominant phase of the concentrated fines stream (414).

- 27 -[0095] The concentrated fines stream (414) may be mixed with additional solids prior to agglomeration. For example, the concentrated fines stream (414) may be mixed with oil sand slurry prior to agglomeration. The larger sand particles that are within the oil sand slurry may provide additional surface for the fines to agglomerate on.
[0096] As mentioned above, effective agglomeration of solids may require a solids concentration of greater than 30 wt. %, or more preferably, greater than 40 wt. %. The bitumen extract stream (406) may have solids concentration of less than 30 wt.
% solids, or more likely may have solids concentration of less than 20 wt.% solids. For this reason, it is desirable to concentrate the fines by the process described herein in order to produce a slurry more suitable for solids agglomeration.
[0097] The agglomerated fines (418) may be washed with a washing solvent using a filter. The agglomerated fines (418) may be placed directly on the filter media and washed counter-currently with the solvent. The filter may be as described above with reference to Figure 2. The agglomerated fines (418) may be mixed with additional agglomerated solids prior to filtration with the filter. The additional agglomerated solids may be from an agglomerated oil sand slurry.
[0098] Removing fines from the bitumen extract stream (406) in the way shown in Figure 4 may have the advantage of providing an effective method for recovering bitumen from the separated fines without re-dispersing the fines in a fluid. For example, the bitumen may be recovered by countercurrent washing of the agglomerated fines with a filter.
Recovering bitumen by filtration may be more efficient than multiple stages of fluid washing and concentrating of the fines in vessels. Additionally, the fines may be dried to a solvent content of less than 5 wt. % during the drying stage of the filter. The initial drying of the fines within the filter may reduce the required load on the tailings solvent recovery unit (427).
[0099] The separation process with the separator 410 may produce a low fines bitumen extract stream (412) that has a solids content of less than 0.1 wt. %
on a dry bitumen basis. As described in the background section, achieving this level of solid content in the low fines bitumen extract stream requires the removal of the oleophilic fines that are in a stable

- 28 -CA 02863487 201.4-09-11 suspension with the low fines bitumen extract stream. The removal of these oleophilic fines may be assistcd by precipitating asphaltenes and/or by adding additives to help aggregate the fines into larger particles that can be more readily separated from the low fines bitumen extract stream. Asphaltene precipitation can be induced by adding or removing solvent from the bitumen extract stream, changing the temperature, and/or by changing the pressure of the bitumen extract stream. One way to induce asphaltene precipitation is to add a paraffinic solvent, such as but not limited to pentane, to the bitumen extract stream.
Applicable additives that can be used to help aggregate the fines include chemical additives, such as surfactants, flocculants, and coagulants. The chemical additive can be water soluble where an aqueous solution of the chemical additive is mixed with the bitumen extract.
The chemical additive can be directly miscible in the hydrocarbon phase. Other classes of additives that may be suitable include solid additives. Examples of solid additives include, but are not limited to, clays, molecular sieves, activated carbon, and carbon black. The solid additives, which may be much larger particles than the fines, absorb and/or adsorb the fines prior to being separated from the bitumen extract.
[001001 Flocculation may be used to assist solid-liquid separation. It is well known that flocculation of fines within an aqueous fluid is dependent on the sands-to-fines ratio (S:F) of the slurry. The flocs, which are comprised of an aggregation of the solids and flocculants, are larger at higher S:F and as result the settling rate of the flocs is higher.
The S:F of the bitumen extract stream used herein may be controlled in order to optimize the separation process with separator (410). For example, the S:F of the bitumen extract stream described above may be increased by adding coarse solids to the bitumen extract stream.
The S:F may be increased to produce larger aggregates with the precipitated asphaltenes and/or additives.
The larger aggregates may have a faster settling rate. The S:F of the bitumcn extract stream may be controlled by mixing it with a portion from the coarse solids stream.
The S:F of the bitumen extract may be controlled to produce a concentrated fines stream (414) more suitable for solids agglomeration. The increased amount of sand in the concentrated fines steam (414) may improve the agglomeration process.

- 29 -, 1001011 It should be understood that numerous changes, modifications, and alternatives to the preceding disclosure can be made without departing from the scope of the disclosure.
= The scope of the claims should not be limited by particular embodiments set forth herein, but should be construed in a manner consistent with the specification as a whole.

-30-

Claims (48)

CLAIMS:

1. A method comprising:
(a) providing a bitumen extract stream, comprising bitumen dissolved in a first solvent, and suspended fines;
(b) separating the bitumen extract stream into a concentrated fines stream and a low fines bitumen extract stream;
(c) producing agglomerated fines by agglomerating the concentrated fines stream;
(d) forming washed agglomerated fines by washing the agglomerated fines with a washing solvent that removes residual bitumen extract from the agglomerated fines;
(e) producing dry solids by removing the washing solvent from the washed agglomerated fines; and producing a bitumen product stream by removing the first solvent from the low fines bitumen extract stream.

2. The method of claim 1, further comprising, prior to (a):
forming an oil sand slurry, comprising a bitumen extract and solids, by contacting a bituminous feed with an extraction liquor;
forming an agglomerated slurry by adding a bridging liquid to the oil sand slurry to agglomerate the solids as agglomerated solids; and forming the bitumen extract stream by separating the bitumen extract from the agglomerated solids.

3. The method of claim 1, further comprising, prior to (a):
forming an oil sand slurry, comprising a bitumen extract and solids, by contacting a bituminous feed with an extraction liquor; and separating the oil sand slurry into the bitumen extract stream and a coarse solids stream, wherein a weight majority of fine solids within the oil sand slurry are in the bitumen extract stream and a weight majority of coarse solids within the oil sand slurry are in the coarse solids stream.

4. The method of claim 2, further comprising mixing a portion of the concentrated fines stream with a portion of the oil sand slurry.

5. The method of any one of claims 1 to 4, wherein (b) is effected by gravity separation or enhanced gravity separation.

6. The method of claim 5, wherein (b) is effected within a thickener.

7. The method of any one of claims 1 to 6, further comprising forming precipitated asphaltenes by precipitating asphaltenes within the bitumen extract stream.

8. The method of claim 7, further comprising separating the precipitated asphaltenes and the fines from a weight majority of the bitumen.

9. The method of claim 7, wherein the asphaltenes are precipitated in the bitumen extract stream by adding a second solvent to the bitumen extract stream.

10. The method of claim 9, wherein the second solvent is a paraffinic solvent.

11. The method of claim 7, wherein precipitating asphaltenes comprises changing a temperature of the bitumen extract stream.

12. The method of claim 7, wherein precipitating asphaltenes comprises changing the pressure of the bitumen extract stream.

13. The method of any one of claims 1 to 12, wherein separating the bitumen extract stream comprises adding a chemical additive to the bitumen extract stream.

14. The method of claim 13, wherein the chemical additive is at least one of a surfactant, flocculent, and coagulant.

15. The method of claim 14, wherein the chemical additive is a water soluble additive and wherein the method further comprises adding an aqueous solution, comprising the chemical additive, to the bitumen extract stream.

16. The method of claim 14, wherein the chemical additive is miscible with the bitumen extract stream.

17. The method of any one of claims 1 to 16, wherein separating the bitumen extract stream comprises adding a solid additive to the bitumen extract stream.

18. The method of claim 17, wherein the solid additive is at least one of a sand, a clay, a molecular sieve, activated carbon, and carbon black.

19. The method of any one of claims 1 to 18, wherein the bitumen product stream has a solids content of less than 0.5 wt. %.

20. The method of any one of claims 1 to 18, wherein the bitumen product stream has a solids content of less than 0.1 wt. %.

21. The method of any one of claims 1 to 20, wherein the concentrated fines stream is agglomerated within a mixing tank, a rotating vessel, or a pipeline.

22. The method of any one of claims 1 to 21, wherein agglomerating the concentrated fines stream comprises adding a bridging liquid to the concentrated fines stream.

23. The method of claim 22, wherein the bridging liquid is an aqueous liquid.

24. The method of claim 22, wherein the bridging liquid comprises an agglomerating assisting additive.

25. The method of any one of claims 1 to 24, further comprising mixing the concentrated fines stream with additional solids prior to agglomerating the concentrated fines stream.

26. The method of any one of claims 1 to 25, wherein washing the agglomerated fines comprises using a filter.

27. The method of any one of claims 1 to 26, wherein washing the agglomerated fines comprises washing the agglomerated fines counter-currently with the washing solvent.

28. The method of claim 26, wherein the filter comprises a drainage portion upstream of a washing portion.

29. The method of claim 26 or 28, wherein the filter comprises a drying portion.

30. The method of any one of claims 1 to 29, further comprising mixing the agglomerated fines with additional agglomerated solids prior to washing the agglomerated fines.

31. The method of any one of claims 1 to 30, wherein (b) results in a formation of three layers: a low fines bitumen extract layer, an interface layer, and an aqueous layer.

32. The method of claim 31, wherein the interface layer comprises the concentrated fines stream.

33. The method of claim 31, wherein the interface layer has water as a continuous phase.

34. The method of any one of claims 31 to 33, wherein the aqueous layer is reused in (b).

35. The method of any one of claims 1 to 30, wherein (b) results in the formation of two layers: a low fines bitumen extract layer and an aqueous layer.

36. The method of claim 35, wherein the aqueous layer comprises the concentrated fines stream.

37. The method of claim 35 or 36, further comprising producing a dewatered concentrated fines stream by separating the fine solids within the aqueous layer from a weight majority of water.

38. The method of claim 37, wherein the dewatered concentrated fines stream has water as a continuous phase.

39. The method of claim 22, wherein the concentrated fines stream is used as the bridging liquid.

40. The method of claim 22, wherein (b) results in a formation of three layers: a low fines bitumen extract layer, an interface layer, and an aqueous layer, and wherein a portion of the interface layer is the bridging liquid.

41. The method of claim 22, wherein (b) results in a formation of two layers: a low fines bitumen extract layer and an aqueous layer, and wherein a portion of the aqueous layer is the bridging liquid.

42. The method of claim 22, wherein (b) results in a formation of two layers: a low fines bitumen extract layer and a aqueous layer, and wherein the fine solids within the aqueous layer are separated from a weight majority of water to produce a dewatered concentrated fines stream, and wherein a portion of the dewatered concentrated fines stream is used as the bridging liquid.

43. The method of any one of claim 1 to 42, further comprising controlling a sands-to-fines ratio of the bitumen extract stream.

44. The method of claim 3, further comprising controlling a sands-to-fines ratio of the bitumen extract stream and increasing the sands-to-fines ratio by mixing the bitumen extract stream with a portion of the coarse solids stream.

45. The method of any one of claims 1 to 44, wherein the concentrated fines stream has a solids content of greater than 30 wt. %.

46. The method of any one of claims 1 to 44, wherein the concentrated fines stream has a solids content of greater than 40 wt. %.

47. The method of any one of claims 1 to 46, wherein the dry solids have a liquid content of less than 15 wt.%.

48. The method of any one of claims 1 to 42, further comprising increasing a sands-to-fines ratio and a solids content of the bitumen extract stream by adding coarse solids to the bitumen extract stream.