CA2928473A1 - Paraffinic froth treatment - Google Patents

Abstract

Described is a paraffinic froth treatment (PFT) process. Paraffinic solvent and a bitumen froth comprising bitumen, water, and solids are added to a froth settling unit (FSU). Following settling in the FSU, hydrocarbon-rich overflow and a solids-rich underflow is produced from the FSU. A portion of the solids-rich underflow is recirculated into the FSU via a recirculation stream for increasing bitumen recovery.

Description

PARAFFINIC FROTH TREATMENT
BACKGROUND
Field of Disclosure [0001] The disclosure relates generally to the field of oil sand processing. More specifically, the disclosure relates to paraffinic froth treatment.
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 water, steam or solvents to extract the heavy oil. Where the oil sand is treated with water, the technique may be referred to as water-based extraction (WBE). WBE is a commonly used process to extract bitumen from mined oil sand.

[0005] In an example of WBE, mined oil sands are mixed with water to create a slurry suitable for extraction. Caustic may be added to adjust the slurry pH to a desired level and thereby enhance the efficiency of the separation of bitumen.

[0006] Regardless of the type of WBE employed, the extraction process will typically result in the production of a bitumen froth comprising bitumen, water, and solids and a tailings stream comprising solids and water. The tailings stream may consist essentially of coarse solids and some fines and water. A typical composition of bitumen froth may be about 60 weight (wt.) % bitumen, 30 wt. % water, and 10 wt. % solids. A bitumen froth may be, for instance, 40-80 wt. % bitumen, 10-50 wt. % water, and 2-30 wt. % (or 5-15 wt.
%) solids. The water and solids in the froth are considered as contaminants. The contaminants may be substantially eliminated or reduced to a level suitable for feed to an oil refinery or an upgrading facility, respectively. Elimination or reduction of the contaminants may be referred to as a froth treatment process. Elimination or reduction of the contaminants may be achieved by diluting the bitumen froth with a solvent. The solvent may comprise any suitable solvent, such as an organic solvent. For example, the organic solvent may comprise naphtha solvent and/or paraffinic solvent. Diluting the bitumen with solvent (also referred to as dilution) may increase the density differential between bitumen and water and solids.
Diluting the bitumen with solvent may enable the elimination or reduction of contaminants using multi-stage gravity settlers. Use of the multi-stage gravity settlers may result in a "diluted bitumen froth"
and another tailings stream. The another tailings stream may be commonly referred to as the froth treatment tailings. The froth treatment tailings may comprise residual bitumen, residual solvent, solids and water. The froth treatment tailings stream may be further processed to recover residual solvent, for instance in a tailings solvent recovery unit (TSRU). If the solvent is paraffinic solvent, the froth treatment tailings may be referred to as "paraffinic froth treatment tailings" and comprise precipitated asphaltenes.

[0007] Figure 1 is a flow diagram of a conventional paraffinic froth treatment (PFT).
Bitumen froth (2) is added to a froth setting unit (FSU) (4) to produce a hydrocarbon-rich overflow (6) and a solids-rich underflow (8). Solvent (not shown) is removed from the hydrocarbon-rich overflow (6) to produce a bitumen product (not shown).
Solvent (10) is added to the solids-rich underflow (8) and is fed to another froth settling unit (FSU-2) (12).
FSU-2 (12) produces a second hydrocarbon-rich overflow (14) and a second solids-rich underflow (16). The second hydrocarbon-rich overflow (14) is added to the FSU
(4) as the solvent source and may be combined with the bitumen froth (2) before its addition to the FSU
(4), as illustrated. The second solids-rich underflow (16) may be combined with dilution water (18) and passed to a tailings solvent recovery unit (TSRU) (20). The TSRU produces a solvent stream (22) and tailings (24).

[0008] At a high level, PFT serves to separate water and solids from the bitumen.
Most of the water and solids, along with precipitated asphaltenes, end up in the tailings. The degree of bitumen recovery is therefore an important parameter in PFT.

[0009] There is a need for an alternative or improved paraffinic froth treatment to recover bitumen.
SUMMARY

[0010] It is an object of the present disclosure to provide a paraffinic froth treatment to recover bitumen.

[0011] Described is a paraffinic froth treatment (PFT) process.
Paraffinic solvent and a bitumen froth comprising bitumen, water, and solids are added to a froth settling unit (FSU).
Following settling in the FSU, hydrocarbon-rich overflow and a solids-rich underflow is produced from the FSU. A portion of the solids-rich underflow is recirculated into the FSU
via a recirculation stream for increasing bitumen recovery.

[0012] 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

[0013] 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.

[0014] Figure 1 is a flow diagram of a conventional paraffinic froth treatment.

[0015] Figure 2 is a flow chart of an embodiment of a paraffinic froth treatment described herein.

[0016] Figure 3 is a flow diagram of an embodiment of a paraffinic froth treatment described herein.

[0017] Figure 4 is a flow diagram of an embodiment of a paraffinic froth treatment described herein.

[0018] Figure 5 is a flow diagram of an embodiment of a paraffinic froth treatment described herein.

[0019] Figure 6 is a bar graph illustrating fractional solvent and bitumen carry under from paraffinic solvent addition as described herein as compared to a conventional process.

[0020] 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

[0021] 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.

[0022] 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.

[0023] Throughout this disclosure, where a range is used, any number between or inclusive of the range is implied.

[0024] 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.

[0025] "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. %).
In addition, bitumen can contain some water and nitrogen compounds ranging from less than 0.4 wt. % to in excess of 0.7 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.

[0026] "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 10.00 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.

[0027]
"Fine particles", "fine solids", or "fines" are generally defined as those solids having a size of less than 44 microns (,tm), that is, material that passes through a 325 mesh (44 micron).

[0028]
"Coarse particles" or "coarse solids" are generally defined as those solids having a size of greater than 44 microns ( m).

[0029]
The term "solvent" as used in the present disclosure should be understood to mean either a single solvent, or a combination of solvents.

[0030]
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.

[0031]
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.

[0032]
The term "paraffinic solvent" (also known as aliphatic) as used herein means solvents comprising normal paraffins, isoparaffins or blends thereof in amounts greater than 50 wt. %. Presence of other components such as olefins, aromatics or naphthenes may counteract the function of the paraffinic solvent and hence may be present in an amount of only 1 to 20 wt. % combined, for instance no more than 3 wt. %. The paraffinic solvent may be a C4 to C20 or C4 to C6 paraffinic hydrocarbon solvent or a combination of iso and normal components thereof The paraffinic solvent may comprise n-pentane, iso-pentane, or a combination thereof The paraffinic solvent may comprise about 60 wt. % pentane and about 40 wt. % iso-pentane, with none or less than 20 wt. % of the counteracting components referred above.

[0033] Figure 2 is a flow chart of an embodiment of a paraffinic froth treatment (PFT) process. Paraffinic solvent and a bitumen froth comprising bitumen, water, and solids is added (202) to a froth settling unit (FSU). Following settling in the FSU, hydrocarbon-rich overflow and a solids-rich underflow is produced (204) from the FSU. A portion of the solids-rich underflow is recirculated (206) into the FSU via a recirculation stream for increasing bitumen recovery.

[0034] Figure 3 is a flow diagram of a PFT using two recirculation streams. Bitumen froth (302) may be added to a froth setting unit (FSU) (304) to produce a hydrocarbon-rich overflow (306) and a solids-rich underflow (308). A bitumen froth may comprise bitumen, water, and solids, for instance, 40-80 wt. % bitumen, 10-50 wt. % water, and 2-30 wt. % (or 5-15 wt. %) solids. Paraffinic solvent (not shown) may be removed from the hydrocarbon-rich overflow (306) to produce a bitumen product (not shown). In contrast to the conventional PFT illustrated in Figure 1, a portion of the solids-rich underflow (308) may be recirculated into the FSU (304) via a first recirculation stream (331) for increasing bitumen recovery.
Another portion (line 333) of the solids-rich underflow (308) may be combined with paraffinic solvent (310) (line 336) to form a combined stream (335). The combined stream (335) may be passed to a downstream froth settling unit (FSU-2) (312). By settling, the FSU-2 (312) may form a second hydrocarbon-rich overflow (314) and a second solids-rich underflow (316).

[0035] Additionally (as illustrated in Figure 3) or alternatively, a portion of the second solids-rich underflow (316) may be recirculated into FSU-2 (312) via a second recirculation stream (334) for increasing bitumen recovery. The paraffinic solvent (310) may be added to the solids-rich underflow (308) (line 336), as described above, and/or to the second recirculation stream (334) (line 338).

[0036] The second hydrocarbon-rich overflow (314) may be added to the FSU
(304) as the paraffinic solvent source and may be combined with the bitumen froth (302) before its addition to the FSU (304), as illustrated.

[0037] The recirculation stream (331) may be introduced into the FSU
(304) by first combining with a fraction of the second hydrocarbon-rich overflow (314), (line 332).

[0038] The second solids-rich underflow (316) may be combined with dilution water (318) and the portion not recirculated (line 339) may be passed to a tailings solvent recovery unit (TSRU) (320). Steam or an inert gas may be introduced into the TSRU to vaporize and remove paraffinic solvent. The TSRU may produce a paraffinic solvent stream (322) and tailings (324). Recovered paraffinic solvent may be recycled to the process.
The tailings (324) may be directed to a tailings deposition area or processed further in tailings processing facilities.

[0039] The described recirculation is purposed to assist bitumen recovery. The recirculation increases the counter-current nature of the PFT process without having to add additional FSUs. In this way, a higher driving force may be achieved to assist bitumen recovery.

[0040] Any suitable device may be used for recirculation, for instance, a centrifugal pump. The paraffinic solvent may be mixed with the recirculation streams using any suitable device, for instance, static mixers or an impinging jet, with the mixing device disposed close to the paraffinic solvent addition point.

[0041] The recirculation streams may be fed to a variety of locations in the FSU(s) including, but not limited to, a feed inlet through which the bitumen froth (302) is introduced into the FSU (304) or through which the combined stream (335) is introduced into the FSU-2 (312). The feed location and flow rates of the recirculation streams into the FSUs may be used to disrupt the flow pattern within the vessel below the feed inlet so as to achieve a longer residence time and higher contacting efficiency for hydrocarbon extraction from the aggregates. Additionally, the residence time of aggregates or flocs may be manipulated through the use of appropriate vessel internals, such as baffles.

[0042] For the first recirculation, the weight ratio of the recirculation stream to the bitumen froth may be between 0.05:1 and 10:1.

[0043] For the second recirculation, the weight ratio of the second recirculation stream to the portion of the solids-rich underflow added to the FSU-2 may be between 0.05:1 and 10:1.

[0044] The FSUs may be any suitable unit for gravity settling froth. The FSUs may comprise a vertical tank and a conical bottom. The underflow may be withdrawn from the bottom of the FSUs. The bottom of the FSUs may be within the conical bottom.
The overflow has a higher liquid content (by weight) and a lower solid content (by weight) than the underflow. The overflow of the FSU may comprise of less than 1 wt. %, or less than 0.1 wt. % fines. The overflow of the FSU may have less than 10 wt. %, or less than 8 wt. %, asphaltenes.

[0045] The hydrocarbon-rich overflow of the FSU may comprise bitumen and paraffinic solvent. Paraffinic solvent may be recovered from the overflow. For example, the overflow may be passed through a solvent recovery unit (SRU) or other suitable apparatus in which the paraffinic solvent is flashed off and condensed in a condenser associated with the solvent flashing apparatus and recycled/reused in the process. The SRU may be any suitable SRU, for instance a fractionation vessel.

[0046] With reference to Figure 4, instead of adding the FSU-2 overflow (414) to the recirculation stream (431) of the FSU (404), a fraction (440) of the paraffinic solvent (410) fed to the process may be added to the recirculation stream (431) of the FSU
underflow.
Bitumen froth (402) may be added to a froth setting unit (FSU) (404) to produce a hydrocarbon-rich overflow (406) and a solids-rich underflow (408). Paraffinic solvent (not shown) may be removed from the hydrocarbon-rich overflow (406) to produce a bitumen product (not shown). A portion (433) of the solids-rich underflow (408) may be passed to FSU-2 (412). The FSU-2 (412) may produce a second hydrocarbon-rich overflow (414) and a second solids-rich underflow (416). The second hydrocarbon-rich overflow (414) may be added to the FSU (404) as the solvent source and may be combined with the bitumen froth (402) before its addition to the FSU (404), as illustrated. A portion of the solids-rich underflow (408) may be recirculated into the FSU (404) via a first recirculation stream (431) for increasing bitumen recovery. Additionally (as illustrated in Figure 4) or alternatively, a portion of the second solids-rich underflow (416) may be recirculated into FSU-2 (412) via a second recirculation stream (434) for increasing bitumen recovery. At least a portion of the paraffinic solvent (410) may be added to one or more of the following streams:
the first recirculation stream (431) (line 440), the solids-rich underflow (408) (line 436), and the second recirculation stream (434) (via line 442).

[0047] The second solids-rich underflow (416) may be combined with dilution water (418) and passed to a tailings solvent recovery unit (TSRU) (420). The TSRU
may produce a solvent stream (422) and tailings (424).

[0048] A weight ratio of the paraffinic solvent combined with the recirculation stream (via 440) to the paraffinic solvent added to the FSU-2 (via 436 and 442) may be between 0.2:1 and 0.8:1.

[0049] A weight ratio of the paraffinic solvent combined with the recirculation stream to the paraffinic solvent added to the FSU-2 may be between 0.1:1 and 3:1.

[0050] In Figures 3 and 4, the recirculation is shown back to the respective settling unit. However, the recirculation need not be so. As illustrated in Figure 5, the paraffinic solvent may be added to the underflow stream of the FSU rather than only the recirculation stream. This configuration may allow for added extraction while minimizing the reduction in the solvent concentration entering FSU-2.

[0051] In Figure 5, the solvent addition differs from Figures 3 and 4.
Bitumen froth (502) may be added to a froth setting unit (FSU) (504) to produce a hydrocarbon-rich overflow (506) and a solids-rich underflow (508). Paraffinic solvent (not shown) may be removed from the hydrocarbon-rich overflow (506) to produce a bitumen product (not shown). A portion (533) of the solids-rich underflow (508) may be passed to FSU-2 (512).
The FSU-2 (512) may produce a second hydrocarbon-rich overflow (514) and a second solids-rich underflow (516). The second hydrocarbon-rich overflow (514) may be added to the FSU (504) as the solvent source and may be combined with the bitumen froth (502) before its addition to the FSU (504), as illustrated. A portion of the solids-rich underflow (508) may be recirculated into the FSU (504) via a first recirculation stream (531) for increasing bitumen recovery. Additionally (as illustrated in Figure 5) or alternatively, a portion of the second solids-rich underflow (516) may be recirculated into FSU-2 (512) via a second recirculation stream (534) for increasing bitumen recovery. Paraffinic solvent (510) may be added to one of more of the following streams: the solids-rich underflow (508) (via line 544), the portion (533) of the solids-rich underflow (508) (via line 536), and the second recirculation stream (534) (via line 542).

[0052] The second solids-rich underflow (516) may be combined with dilution water (518) and passed to a tailings solvent recovery unit (TSRU) (520). The TSRU
may produce a solvent stream (522) and tailings (524).

[0053] While two FSUs are illustrated in Figures 3 to 5, any suitable number of FSUs may be used and recirculation may be performed on anywhere from one to all of the FSUs in the PFT. For instance, a process having two FSUs but using recirculation only in the second FSU may comprise:
a. adding a paraffinic solvent and a bitumen froth comprising bitumen, water, and solids to a froth settling unit (FSU);
b. following settling in the FSU, producing a hydrocarbon-rich overflow and a solids-rich underflow from the FSU;
c. passing the solids-rich underflow to a downstream froth settling unit (FSU-2), together with paraffinic solvent, to form, following settling, a second hydrocarbon-rich overflow and a second solids-rich underflow; and d. recirculating a portion of the second solids-rich underflow into the FSU-2 via a second recirculation stream for increasing bitumen recovery.
Experimental

[0054] Multiple recirculation configurations were tested in a 2.3 tpd froth capacity two stage FSU PFT pilot plant, operating the first stage FSU around 70 C and the second stage FSU (FSU-2) around 90 C. In these tests, the paraffinic solvent addition rate to the process was fixed, but the addition was split between the conventional injection point (line 336) and the new injection point in an established FSU-2 underflow recirculation system (line 338), as in Figure 3, at split fractions of 33% (via the conventional injection point) - 67% (via the new injection point) and 50%-50% (via conventional injection point vs. new injection point). The results from the 33%-67% experimentation and from the 50%-50%
experimentation are shown in the two upper bars in the graph in Figure 6.

[0055] This experimentation was also run with the "base" solvent injection (all solvent injected into the FSU-1 underflow to FSU-2) with recirculating 50% of the FSU-2 underflow back to the FSU-2 (see line 334 in Figure 3). In this case, the flow rate to FSU-2 was doubled so that the FSU-2 underflow to solvent recovery (see line 339 in Figure 3) remained the same as in the base case operation. In this experiment, all solvent was injected via the conventional injection point (see line 336 in Figure 3). The results from this experimentation is shown in the third bar from the top in the graph in Figure 6, labeled "Base with Recirc".

[0056] As a baseline, the conventional process was run (all solvent injected into the FSU-1 underflow to FSU-2) without any recirculation of FSU-2 underflow. The result from this experimentation is shown in the bottom bar in the graph in Figure 6, labeled "Base".

[0057] All cases were run at the same total solvent injection rate to the system.

[0058] As seen from these results in Figure 6, it has been discovered that adding solvent to the FSU-2 recirculation stream (see two upper bars in the graph in Figure 6) decreased bitumen losses as compared to the conventional PFT process (see bottom bar in the graph in Figure 6).

[0059] Additionally, it has been discovered that recirculation of a part of the FSU-2 underflow (see third bar from the top in the graph in Figure 6) without any modification to the paraffinic solvent addition to the system also decreased bitumen losses as compared to the conventional PFT process (see bottom bar in the graph in Figure 6).

[0060] 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 preceding description, therefore, is not meant to limit the scope of the disclosure. Rather, the scope of the disclosure is to be determined only by the appended claims and their equivalents. It is also contemplated that structures and features in the present examples can be altered, rearranged, substituted, deleted, duplicated, combined, or added to each other.

Claims (25)

CLAIMS:

1. A process comprising:
a) adding a paraffinic solvent and a bitumen froth comprising bitumen, water, and solids to a froth settling unit (FSU);
b) following settling in the FSU, producing a hydrocarbon-rich overflow and a solids-rich underflow from the FSU; and c) recirculating a portion of the solids-rich underflow into the FSU via a recirculation stream for increasing bitumen recovery.

2. The process of claim 1, wherein a weight ratio of the recirculation stream to the bitumen froth is between 0.05:1 and 10:1.

3. The process of claim 1 or 2, further comprising passing another portion of the solids-rich underflow to a downstream froth settling unit (FSU-2), together with paraffinic solvent, to form, following settling, a second hydrocarbon-rich overflow and a second solids-rich underflow.

4. The process of claim 3, further comprising adding the second hydrocarbon-rich overflow to the FSU, wherein the second hydrocarbon-rich overflow is used as a source of the paraffinic solvent.

5. The process of claim 4, wherein the second hydrocarbon-rich overflow is split and combined separately with the bitumen froth and with the recirculation stream prior to addition to the FSU.

6. The process of claim 3 or 4, further comprising combining the recirculation stream with paraffinic solvent as a source of the paraffinic solvent, and then combining with the bitumen froth and the second hydrocarbon-rich overflow, and then adding a resultant stream into the FSU.

7. The process of claim 6, wherein a weight ratio of the paraffinic solvent combined with the recirculation stream to the paraffinic solvent added to the FSU-2 is between 0.1:1 and 3:1.

8. The process of any one of claims 3 to 7, further comprising recirculating a portion of the second solids-rich underflow into the FSU-2 via a second recirculation stream for increasing bitumen recovery.

9. The process of claim 8, wherein a weight ratio the second recirculation stream to the portion of the solids-rich underflow added to the FSU-2 is between 0.05:1 and 10:1.

10. The process of any one of claims 3 to 9, wherein at least a portion of the paraffinic solvent is added to at least one of the solids-rich underflow and the portion of the solids-rich underflow to be added to the FSU-2.

11. The process of claim 8 or 9, wherein at least a portion of the paraffinic solvent is added to the second recirculation stream.

12. The process of any one of claims 2 to 11, further comprising adding dilution water to the second solids-rich underflow to enhance flow of the second solids-rich underflow.

13. The process of any one of claims 3 to 11, wherein the paraffinic solvent is mixed with the other portion of the solids-rich underflow using a mixing device or pump.

14. The process of any one of claims 1 to 13, further comprising removing the solvent from the hydrocarbon-rich overflow to form a bitumen product.

15. The process of any one of claims 3 to 12, further comprising removing solvent from at least a portion of the second solids-rich underflow to form a tailings stream.

16. The process of any one of claims 1 to 15, wherein the paraffinic solvent comprises greater than 50 volume % pentane, based on a weight of the paraffinic solvent.

17. A process comprising:
a) adding a paraffinic solvent and a bitumen froth comprising bitumen, water, and solids to a froth settling unit (FSU);
b) following settling in the FSU, producing a hydrocarbon-rich overflow and a solids-rich underflow from the FSU;
c) passing the solids-rich underflow to a downstream froth settling unit (FSU-2), together with paraffinic solvent, to form, following settling, a second hydrocarbon-rich overflow and a second solids-rich underflow; and d) recirculating a portion of the second solids-rich underflow into the FSU-2 via a second recirculation stream for increasing bitumen recovery.

18. The process of claim 17, further comprising adding the second hydrocarbon-rich overflow to the FSU, wherein the second hydrocarbon-rich overflow is used as a source of the paraffinic solvent.

19. The process of claim 17 or 18, wherein a weight ratio the second recirculation stream to the solids-rich underflow added to the FSU-2 is between 0.05:1 and 10:1.

20. The process of any one of claims 17 to 19, wherein at least a portion of the paraffinic solvent is added to the second recirculation stream.

21. The process of any one of claims 17 to 20, further comprising adding dilution water to the second solids-rich underflow to enhance flow of the second solids-rich underflow.

22. The process of any one of claims 17 to 21, wherein the paraffinic solvent is mixed with the solids-rich underflow using a mixing device or pump.

23. The process of any one of claims 17 to 22, further comprising removing the solvent from the hydrocarbon-rich overflow to form a bitumen product.

24. The process of any one of claims 17 to 23, further comprising removing solvent from at least a portion of the second solids-rich underflow to form a tailings stream.

25. The process of any one of claims 17 to 24, wherein the paraffinic solvent comprises greater than 50 volume % pentane, based on a weight of the paraffinic solvent.