CA2907155C - Product cleaning of bitumen extracted from oil sands solvent extraction processes - Google Patents

Abstract

A bitumen extract stemming from solvent-based extraction and an aliphatic solvent are counter-currently passed through one another to produce a light phase comprising deasphalted oil and aliphatic solvent, and a heavy phase comprising asphaltenes, water, and solids.

Description

PRODUCT CLEANING OF BITUMEN EXTRACTED FROM OIL SANDS SOLVENT
EXTRACTION PROCESSES
BACKGROUND
Field of Disclosure [00011 The disclosure relates generally to the field of oil sand processing. More specifically, the disclosure relates to field of solvent-based bitumen extraction.
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.

[0003] 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.

[0004] Recently, the harvesting of oil sand to remove heavy oil has become more economical. Hydrocarbon 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 I

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.

[0005] 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.) %, on a dry bitumen basis "Dry bitumen basis" means ignoring the presence of water in the bitumen for the purpose of calculating wt. %.

[0006] A solid agglomeration process has been proposed for use in the solvent-based recovery 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 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.

[0007] 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.

[0008]
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 are that which favor the formation of large agglomerates; however, a light milling action is used to continuously break down the large agglomerates. The micro-agglomerates are formed by obtaining an eventual equilibrium between cohesive and destructive forces.
Since 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.

[0009]
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 are un-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.

[0010] 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.
4,888,108 (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 be 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.

[0011] 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.
Application Publication No. 2011/0127197 (Blackbourn 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 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. Blackbourn 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 produce a bitumen extract with fine solids content of less than 0.1 wt.% on a dry bitumen basis.

[0012] The use of aliphatic solvents in a solvent-based recovery process has been proposed as a method to reduce the amount of residual solvent in tailings. U.S. Patent No. 8,257,580 (Duyvesteyn et al.) describes a method for preparing dry, stackable tailings.
Dry, stackable tailings may be defined as comprising less than 0.1 wt.% solvent and from about 2 wt. % to about 15 wt. % water, based on a weight of the tailings. The method involves contacting the oils sand with a light aromatic solvent to dissolve bitumen. The bitumen extract is then separated from the solids in order to produce a first solid tailings that has residual bitumen extract entrained within. The residual bitumen extract is removed from the tailings by washing the solids with a light hydrocarbon solvent to produce solvent-wet tailings where the remaining light hydrocarbon solvent can be readily recovered by heating and/or pressure reduction. A light hydrocarbon solvent may be defined as a cyclo- or iso-paraffin having between 3 and 9 carbons. The light hydrocarbon solvent is typically an aliphatic solvent such as at least one of propane, butane, and pentane. Duyvesteyn et al. describes that this method has the potential advantage of reducing the required energy to recover the light hydrocarbon solvent from tailings and the potential advantage of requiring that only the washing stage needs to be pressurized in the solvent-based recovery process.

[0013] Solvent-based extraction may produce a bitumen extract having approximately 1-3 wt. % solids and 0.5-2 wt. % water, based on a weight of the bitumen extract.

[0014] It is desirable to provide an alternative process for reducing the solids content of a bitumen extract stemming from solvent-based extraction.

[0015] Deasphalting evolved in the 1930s as a solvent extraction process for lubes bright stock manufacture. It involved contacting the heavy vacuum residue with liquid propane solvent in countercurrent fashion using a variety of tower and internal configurations. The liquid propane dissolves the lower molecular weight and more saturated oils while precipitating the heavy aromatics, resins, and asphaltenes which may be referred to as tar or rock. Solvent deasphalting is very selective for metals and concarbon; i.e.
metals and concarbon are preferentially rejected into the tar / rock stream. Heavier liquid alkane solvents such as butane and pentane have since been used commercially for fuels applications as they produce a less selective deasphalted oil. As the solvent molecular weight increases, deasphalted oil yield increases though with a decrease in selectivity. Solvent deasphalting requires the use of liquid solvents thus requiring the appropriate pressure to maintain the solvent in the liquid state.
SUMMARY

[0016] It is an object of the present disclosure to provide a process for reducing the solids content of a bitumen extract stemming from solvent based extraction.

[0017] A bitumen extract stemming from solvent-based extraction and an aliphatic solvent are counter-currently passed through one another to produce a light phase comprising deasphalted oil and aliphatic solvent, and a heavy phase comprising asphaltenes, water, and solids.

[0018] 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

[0019] 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.

[0020] Figure 1 is a flow chart of a process for reducing solids content of a bitumen extract from solvent-based extraction.

[0021] Figure 2 is a flow diagram of a process for reducing solids content of a bitumen extract from solvent-based extraction.

!

[0022] Figure 3 is a flow diagram of a process for reducing solids content of a bitumen extract from solvent-based extraction, which may be integrated with existing water-based extraction froth cleaning processes

[0023] 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

[0024] 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 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.

[0025] 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.

[0026] Throughout this disclosure, where a range is used, any number between or inclusive of the range is implied.

[0027] 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.

[0028] "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);
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. %), based on a weight of the bitumen. =
In addition, bitumen can contain some water and nitrogen compounds ranging from less than 0.4 wt. % to in excess of 0.7 wt. %, based on a weight of the bitumen. 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.

[0029] "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 10.00 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.

[0030] 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 processes which comprises bitumen that would otherwise not have been recovered may be used as a bituminous feed.

[0031] "Fine particles" are generally defined as those solids having a size of less than 44 microns (vim), that is, material that passes through a 325 mesh (44 micron).

[0032] "Coarse particles" are generally defined as those solids having a size of greater than 44 microns (pm).

[0033] A "solvent-based recovery process", "solvent extraction process", "solvent extraction", or "oil sand 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.

[0034] "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.

[0035] "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).

[0036] A "bitumen extract" is generally defined as bitumen that has been extracted from oil sand.

[0037] A "bitumen product stream" or "bitumen product" is generally defined as a high grade bitumen product that may be suitable for transport within pipelines and processing within downstream refineries. A high grade bitumen product stream may have a solids content of less than 1 wt. %, or less than 0.1 wt. %, on a dry bitumen basis.

[0038] The term "solvent" as used in the present disclosure should be understood to mean either a single solvent, or a combination of solvents.

[0039] 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.

[0040] 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.

[0041] "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 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 more 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.

[0042] The present process treats a bitumen extract stemming from a solvent-based extraction process. The solvent-based extraction process may include, but is not limited to, solvent extraction with a solids agglomeration process. Non-limiting examples of solvent extraction 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.).

[0043] Adeyinka et al. discloses extracting bitumen from oil sand in a manner that employs solvent. A first 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 first and second 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 bitumen extracts is conducted to produce bitumen products of commercial value.

[0044]
Figure 1 is a flow chart of a process for reducing solids content of a bitumen extract from solvent-based extraction. A bitumen extract stemming from solvent-based extraction if provided (102) along with and an aliphatic solvent (104). The aliphatic solvent and the bitumen extract are counter-currently passed through one another to produce a light phase comprising deasphalted oil and aliphatic solvent, and a heavy phase comprising asphaltenes, water, and solids (106).

[0045]
Figure 2 is a flow diagram of a process for reducing solids content of a bitumen extract from solvent-based extraction. The bitumen extract (204) stemming from solvent-based extraction may be introduced into a vessel (202). A typical bitumen extract (204) may include bitumen, up to 5 wt. % (more typically up to 1.5 wt. %) solids, and up to 5wt.% (more typically up to 1.5 wt. %) water, based upon a weight of bitumen extract. Any pressure vessel suitable for light liquid aliphatic solvents (206) may be used. The vessel (202) may be a deasphalter, which is known in the art of refinery deasphalting of feeds such as heavy vacuum gas oil, atmospheric residue or vacuum residue. The vessel (202) may be a vertical tower and may include baffle, tray, or packing internals. The internals increase the contacting between the solvent and the bitumen. The aliphatic solvent (206) may be introduced into the vessel (202) to enable countercurrent flow. The light aliphatic solvent (206) and the heavy bitumen feed (204) may be counter-currently passed through one another to produce a light phase (208) comprising deasphalted oil and most of the aliphatic solvent, and a heavy liquid phase (210) comprising resins, asphaltenes, solids, and a small amount of aliphatic solvent. Beneficially, a majority of the solids are contained in the heavy liquid phase (210).

[0046] Any suitable aliphatic solvent (206) may be used. The aliphatic solvent (206) may have greater than 50 wt. % of a C3 to C7 aliphatic hydrocarbon. The aliphatic solvent (206) may have greater than 50 wt. % of n-pentane, iso-pentane, or a combination thereof

[0047] The aliphatic solvent content of the light phase (208) may be reduced downstream, for instance in a solvent recovery unit (not shown), to produce a partially deasphalted bitumen product. The light phase may have an asphaltene content of less than 20 wt. %, less than 12 wt. %, or less than 8 wt. %, based on a weight of the light phase. The partially deasphalted bitumen product may have a solids content of less than 1000 ppmw (parts per million by weight), less than 300 ppmw, less than 100 ppmw, or less than 50 ppmw, based on a weight of the partially deasphalted bitumen product. The partially deasphalted bitumen product may be sent to a refinery for refining. Refinery specifications generally require less than 300 ppmw solids. The partially deasphalted bitumen product may have a water content of less than 1000 ppmw, 500 ppmw, or less than 200 ppmw, based on a weight of the partially deasphalted bitumen product. The partially deasphalted bitumen product may have less than 1300 ppmw combined water and solids, based on a weight of the partially deasphalted bitumen product, which is a typical refinery specification.

[0048] Figure 3 is a flow diagram of a process for reducing solids content of a bitumen extract from solvent-based extraction. Figure 3 shares like elements to Figures 2 as follows:
vessel (302), bitumen extract (304), aliphatic solvent (306), light phase (308), and heavy phase (310). Figure 3 additionally includes processing of the heavy phase (310).

[0049] The heavy phase (310) may be combined with a bitumen froth (312) and paraffinic solvent (314) and froth treatment may be effected on the resulting combination. The bitumen froth (312) may be passed through any suitable froth pump (316). The bitumen froth (312) and paraffinic solvent (314) may be mixed in any suitable mixer (318).
Paraffinic solvent (320) may also or alternatively be added downstream of the mixer (318).

[0050] The paraffinic solvent (314) may be recycled from a PFT process. A
PFT process is described, without limitation, in CA 2,587,166 (Sury). The PFT process may include a two stage froth treatment process including two froth treatment units (also known as froth settling units (FSUs)). The paraffinic solvent (314 and/or 320) may be a second stage FSU overflow, which overflow includes the paraffinic solvent (314 and/or 320). The combination of the heavy phase (310), bitumen froth (312), and paraffinic solvent (314 and/or 320) may be mixed in any suitable mixer (322) and be introduced into an FSU (324). The FSU
(324) may produce a diluted bitumen stream (326) and froth treatment tailings (328).
Heat savings may be realized by such integration with a PFT process.

[0051] The solvent content of the diluted bitumen stream (326) may be reduced, for instance in any suitable solvent recovery unit (not shown), to produce a second bitumen product (not shown).

[0052] Fine solids (defined as having an average particle size of less than 44 microns) in the feed bitumen extract can pass to the heavy phase. Maltenes from the heavy phase may be recovered in the PFT process.

[0053] The solvent used may be n-pentane or any combination of pentane isomers. The process may operate at temperatures between 100 C and 190 C at pressures greater than 450 psig. The solvent to oil ratio may be 4-8:1 on a volume basis.

[0054] The rock / tar solution leaving the bottom of the contacting vessel may be subsequently mixed with the froth at contacting vessel conditions and then subsequently cooled before entering the conventional paraffinic froth treatment process.

[0055] Examples

[0056] An experiment was conducted at a pilot plant. The pilot plant has a 28 foot column with alternating baffles. The feed rate could be adjusted between about 1 and 2 gph (gallons per hour). Syncrude bitumen having about 1 wt. % solids was used as a surrogate for the bitumen extract from a solvent-based extraction. Table 1 illustrates the conditions and results.

[0057] Table 1.
Run Run hours Feed gph Treat Feed Overhead Bottoms Volume Temperature Temperature Temperature # (gallons per Ratio hour) (Degrees F) (Degrees F) (Degrees F) 1 31 0.99 6.11 207 206 201 2 11 1.07 7.56 309 349 274 3 13 1.02 7.94 296 331 282 4 9 0.97 8.20 300 320 275 21 1.48 6.30 310 312 293

[0058] Solids were found to be less than 50 ppmw in the deasphalted oil (DA0), while water was found to be less than 100 ppmw.

[0059] 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.

Claims (23)

CLAIMS:

1. A process for reducing solids content of a bitumen extract stemming from a solvent-based extraction process, comprising:
a) providing a bitumen extract stemming from solvent-based extraction wherein the bitumen extract has been extracted from oil sand and contains greater than 1 wt. % solids;
b) providing an aliphatic solvent;
c) counter-currently passing the aliphatic solvent and the bitumen extract through one another to produce a light phase comprising deasphalted oil and aliphatic solvent, and a heavy phase comprising asphaltenes, water, and solids; and d) reducing an aliphatic solvent content of the light phase to produce a first bitumen product;
wherein the first bitumen product has less than 1000 ppmw solids, based on a weight of the first bitumen product.

2. The process of claim 1, wherein the aliphatic solvent travels upwards.

3. The process of claim 2, wherein step c) is effected in a vertical tower.

4. The process of claim 2, wherein step c) is effected in a vertical tower comprising baffles, trays, or packed internals.

5. The process of claim 1, wherein the first bitumen product has less than 300 ppmw solids, based on a weight of the first bitumen product.

6. The process of claim 1, wherein the first bitumen product has less than 100 ppmw solids based on a weight of the first bitumen product.

7. The process of claim 1, wherein the first bitumen product has less than 50 ppmw solids based on a weight of the first bitumen product.

8. The process of any one of claims 1 to 7, wherein the first bitumen product has less than 200 ppmw water, based on a weight of the first bitumen product.

9. The process of any one of claims 1 to 7, wherein the first bitumen product has less than 100 ppmw water, based on a weight of the first bitumen product.

10. The process of any one of claims 1 to 7, wherein the first bitumen product has less than 1300 ppmw combined water and solids, based on a weight of the first bitumen product.

11. The process of any one of claims 1 to 10, further comprising refining the first bitumen product.

12. The process of any one of claims 1 to 11, further comprising combining the heavy phase with a bitumen froth and paraffinic solvent, and effecting froth treatment on a resulting combination.

13. The process of claim 12, wherein the paraffinic solvent, which is combined with the heavy phase and the bitumen froth, is recycled from the paraffinic froth treatment process.

14. The process of claim 12 or 13, wherein the froth treatment comprises a two-stage froth treatment process comprising two froth settling units.

15. The process of claim 14, wherein the paraffinic solvent is combined with the heavy phase and the bitumen froth by combining a second stage froth settling unit overflow with the heavy phase, which overflow comprises the paraffinic solvent.

16. The process of any one of claims 12 to 15, wherein the froth treatment produces a diluted bitumen stream and froth treatment tailings.

17. The process of claim 16, further comprising reducing a solvent content in the diluted bitumen stream to produce a second bitumen product.

18. The process of any one of claims 1 to 17, wherein the aliphatic solvent of b) comprises greater than 50 wt. % of a C4 to C7 aliphatic hydrocarbon, based on a weight of the aliphatic solvent of b).

19. The process of any one of claims 1 to 17, wherein the aliphatic solvent of b) comprises greater than 50 wt. % of n-pentane, iso-pentane, or a combination thereof, based on a weight of the aliphatic solvent of b).

20. The method of any one of claims 1 to 19, wherein the heavy phase further comprises aliphatic solvent and non-asphaltenic bitumen.

21. The method of any one of claims 1 to 20, wherein the light phase has an asphaltene content of less than 20 wt. %, based on a weight of the light phase.

22. The method of any one of claims 1 to 20, wherein the light phase has an asphaltene content of less than 12 wt. %, based on a weight of the light phase.

23. The method of any one of claims 1 to 20, wherein the light phase has an asphaltene content of less than 8 wt. %, based on a weight of the light phase.