WO2011014725A1

WO2011014725A1 - Methods for obtaining bitumen from bituminous materials

Info

Publication number: WO2011014725A1
Application number: PCT/US2010/043822
Authority: WO
Inventors: Willem P.C. Duyvesteyn; Julian Kift
Original assignee: Marathon Oil Canada Corporation
Priority date: 2009-07-30
Filing date: 2010-07-30
Publication date: 2011-02-03
Also published as: CA2769528A1

Abstract

Methods for obtaining bitumen from bituminous material. The methods may include a dissolution step where a first solvent is added to material comprising bitumen to dissolve the bitumen contained therein. The majority of the dissolved bitumen is then removed from the mixture of first solvent and material comprising bitumen by filtering or settling the mixture of first solvent and material comprising bitumen. Any residual dissolved bitumen is then removed from the mixture of first solvent and material comprising bitumen by adding additional first solvent to the mixture to displace the residual dissolved bitumen from the mixture.

Description

METHODS FOR OBTAINING BITUMEN FROM BITUMINOUS MATERIALS

BACKGROUND

Bitumen is a heavy type of crude oil that is often found in naturally occurring geological materials such as tar sands, black shales, coal formations, and weathered hydrocarbon formations contained in sandstones and carbonates. Some bitumen can be described as flammable brown or black mixtures or tarlike hydrocarbons derived naturally or by distillation from petroleum. Some bitumen can be in the form of a viscous oil to a brittle solid, including asphalt, tars, and natural mineral waxes. Substances containing bitumen are typically referred to as bituminous, e.g., bituminous coal, bituminous tar, or bituminous pitch. At room temperature, the flowability of some bitumen is much like cold molasses. Bitumen can be processed to yield oil and other commercially useful products, primarily by cracking the bitumen into lighter hydrocarbon material.

As noted above, tar sands represent one of the well known sources of bitumen. Tar sands typically include bitumen, water and mineral solids. The mineral solids can include inorganic solids such as coal, sand, and clay. Tar sand deposits can be found in many parts of the world, including North America. One of the largest tar sands deposits is in the Athabasca region of Alberta, Canada. In the Athabasca region, the tar sands formation can be found at the surface, although it can also be buried two thousand feet below the surface overburden or more. Tar sands deposits are measured in barrels equivalent of oil. It is estimated that the Athabasca tar sands deposit contains the equivalent of about 1.7 to 2.3 trillion barrels of oil. Global tar sands deposits have been estimated to contain up to 4 trillion barrels of oil. By way of comparison, the proven worldwide oil reserves are estimated to be about 1.3 trillion barrels. The bitumen content of some tar sands varies from approximately 3 wt% to 21 wt%, with a typical content of approximately 12 wt%. Accordingly, an initial step in deriving oil and other commercially useful products from bitumen typically requires extracting bitumen from the naturally occurring geological material. In the case of tar sands, this can include separating the bitumen from the mineral solids and other components of tar sands. One conventional process for separating bitumen from mineral solids and other components of tar sands includes mixing the tar sands with hot water and, optionally, a process aid such as caustic soda (see, e.g., U.S. Pat. No. 1,791,797). Agitation of this mixture releases bitumen particles from the tar sands and allows air bubbles to attach to the released bitumen particles. These air bubbles float to the top of the mixture and form a bitumen-enriched froth. In Applicant's experience, such a froth typically includes around 60% bitumen, 30% water, and 10% inorganic minerals. The bitumen-enriched froth is separated from the mixture, sometimes with the aid of a solvent, and further processed to isolate the bitumen product. For example, the froth can be treated with an aliphatic (pentane-type) or an aromatic (naphtha-type) solvent to produce a clean bitumen product that can serve as a refinery upgrader feed stock. The bulk of the mineral solids can also be removed to form a tailings stream. Typically, the tailings stream also includes water, solvent, precipitated asphaltenes (in the case where the asphaltene is not soluble in the solvent used to separate the bitumen-enriched froth from the mixture), and some residual bitumen.

One issue with conventional hot water extraction methods is that they may achieve relatively low bitumen recoveries when used on low grade bituminous materials (e.g., bituminous material having a bitumen content of 10 wt% or less). Low recovery rates will be especially problematic in regions where a regulatory board stipulates a minimum bitumen recovery for certain grades of bituminous material. For example, the Alberta Energy and

Utilities Board has implemented guidelines requiring that the bitumen recovery rate for hot water extraction using naphtha-based froth treatment of ore sands having less than 11% bitumen content satisfy the following equation:

Bitumen Recovery > -2.5*(Ore Grade)² + 54.1*(Ore Grade) - 202.6 (1)

where both Bitumen Recovery and Ore Grade are expressed in wt-%. Figure. 1 provides a graphical representation of Equation (1) set against data for actual bitumen recoveries achieved on ore sands of various grades when using a hot water extraction process using paraffmic froth treatment. In Figure 1, the line marked A represents the minimum required bitumen recovery rate for various ore grades as defined by the Alberta Energy and Utilities Board according to

Equation (1) above, while line B represents a least square fit of a set of extraction data from a hot water extraction operating plant in the Athabasca region. As can be seen in Figure 1 , the actual bitumen recoveries achieved from this set of data in the range between approximately 10% and 11% fall below the board's directive for bitumen extraction. Furthermore, an extrapolation of line B back towards the lower ore grades would suggest that the actual bitumen recoveries from the hot water extraction method continue to fall below the mandated minimum. Accordingly, it is possible that these hot water extraction methods will not be permitted for extracting bitumen from lower grade bituminous material.

The difficulty for conventional hot water extraction methods in extracting bitumen from low grade bituminous materials typically stems from the impact that hot water has on the relatively high content of certain clay components in low grade tar sands ores. In Applicant's experience, the introduction of caustic hot water during the extraction process typically causes certain clay components (e.g., montmorillonite) in the bituminous material to activate and swell, especially when the caustic hot water contains divalent ions such as calcium. The swollen and activated clay will then mix with the water phase introduced to the bituminous material by the hot water extraction methods and produce a clay suspension with a relatively high viscosity and density. If the clay suspension is present rather than just hot water, surfactants produced during the natural weathering of the asphaltene components of the bitumen phase that normally liberate bitumen by reducing interfacial tensions between bitumen particles and sand particles will instead absorb on the clay particles. A reduction in the number of liberated bitumen particles will likely impact the efficient production of a high grade bitumen froth, as there are fewer liberated bitumen particles to attach to air bubbles during the notation step. Furthermore, it is typically more difficult for proper air bubbles to be formed in a clay suspension. As a result of the inability of conventional hot water extraction methods to recover acceptable amounts of bitumen from low grade bituminous materials, the versatility of the conventional methods is curtailed. The conventional methods are limited to processing higher grade bituminous materials, which ultimately makes the conventional methods more expensive to carry out. Additionally, without a method for economically processing low grade bituminous material, a significant portion of the world's bitumen resources can end up going to waste.

Another issue with conventional hot water extraction processes relates to the tailings produced by these processes. For example, tailings produced by conventional methods can include precipitated asphaltenes and/or residual bitumen. The bitumen and asphaltenes in a tailings stream represent unrecovered hydrocarbon that will not be processed into valuable commercial products. Accordingly, the conventional methods typically result in a lower yield of hydrocarbon material, and consequently, diminished profit.

Additionally, the presence of bitumen and asphaltene in the tailings can complicate the disposal of the tailings because theses hydrocarbons can present environmental risks. This may also be true for residual solvent included in the tailings that can be environmentally unfriendly.

The amount of tailings produced by conventional methods can also present significant problems. In some circumstances, the total volume of the tailings produced by the conventional methods is more than the volume of mined tar sands, which means that not all of the tailings can be returned to the mined area. The physical characteristics of the tailings can also present significant problems. The conventional methods utilize water and caustic as part of the process. This can result in the activation and swelling of certain clay components of a tailings stream. Accordingly, the tailings have a sludge-like consistency that can last indefinitely. The sludge-like consistency means that the tailings are not stackable, thereby severely limiting the manner in which to dispose of the tailings. Often the only disposal option is to deposit the tailings in a tailings pond located outside of the mine area. These ponds are costly to build and maintain and can be damaging to the local environment, including the local water supply. Furthermore, ponds can be damaging to the local wildlife population, such as birds, which can be caught in the oil and solvent laden tailings produced by hot- water extraction processes.

One known method for separating bitumen from tar sands that produces tailings having problems as discussed above is described in U.S. Pat. No. 4,347,118 (the '118 patent). The '118 patent discloses a method in which pentane is used to extract bitumen from tar sands. The pentane solvent does not dissolve the asphaltene fraction of the bitumen that is not pentane soluble. Thus, this fraction of the bitumen remains as a solid and is discharged with the tailings. The precipitated C5 asphaltene possesses a complex, card-house type structure that tends to include bitumen and/or solvent, resulting in additional losses of hydrocarbons with the tailings. For Athabasca-type bitumen, the asphaltene precipitate alone can result in a significant loss of the total initial hydrocarbon content of the tar sands, and original bitumen can also be lost to tailings due to inclusions in the asphaitene precipitate. Another bitumen extraction process that produces problematic tailings is described in U.S. Pat. No. 5,143,598 (the '598 patent). The '598 patent discloses a method that includes adding heptane to tar sands to form a bitumen-rich heptane phase and then displacing the bitumen-rich heptane phase with water. The use of heptane can result in the precipitation of the heptane insoluble C7 asphaltene fraction present in the bitumen phase. The heptane insoluble asphaltene fraction is discharged with the tailings.

SUMMARY

Disclosed are embodiments of a method for obtaining bitumen from bituminous materials. In some embodiments, a method for obtaining bitumen from bituminous materials includes mixing a first material comprising bitumen with a first solvent to form a first mixture. The first mixture includes a bitumen-enriched solvent phase. The method also includes separating a first quantity of the bitumen-enriched solvent phase from the first mixture. Separation of the first quantity of the bitumen-enriched solvent phase from the first mixture is accomplished by filtering or settling the first mixture. The method also includes separating a second quantity of the bitumen-enriched solvent phase from the first mixture. Separation of the first quantity of the bitumen-enriched solvent phase is accomplished by adding a second solvent to the first mixture in order to displace the second quantity of bitumen-enriched solvent phase from the first mixture.

In some embodiments, a method for obtaining bitumen from bituminous material includes mixing a material comprising bitumen with a first solvent. The method also includes filtering or separating a first portion of the bitumen-enriched solvent phase from the first result of mixing the material comprising bitumen with the first quantity of first solvent. The method also includes adding a second solvent to a second result of filtering or separating the first portion of the bitumen-enriched solvent phase from the first result.

Also disclosed are embodiments of a method for producing solvent-dry, stackable tailings, and the solvent-dry, stackable tailings produced therefrom. In some embodiments, the method includes a first solvent extraction step performed on material comprising bitumen, a separation step to separate a bitumen-enriched solvent phase and form first solvent-wet tailings, a separation step including the addition of second solvent to the first solvent-wet tailings to displace the first solvent from the first solvent- wet tailings, and a separation step to remove second solvent from the second solvent-wet tailings produced after second solvent displaces the first solvent in the first solvent-wet tailings. In certain embodiments, the addition of first and second solvents to material comprising bitumen is performed without substantial separation steps. Rather, the solvents are allowed to flow through the stationary material comprising bitumen to thereby remove bitumen and first solvent from the material comprising bitumen. Such methods can produce solvent-dry, stackable tailings stream that are easier to dispose of and more environmentally friendly than tailings streams produced by known methods for extracting bitumen from material comprising bitumen.

In some embodiments, a method for producing solvent-dry, stackable tailings includes a step of mixing a first material comprising bitumen with a first solvent to form a first mixture. The first mixture includes a bitumen-enriched solvent phase. The method also includes a step of separating the bitumen-enriched solvent phase from the first mixture. Separation of the bitumen-enriched solvent phase from the first mixture results in the first mixture becoming first solvent- wet tailings that include a first solvent component. The method further includes a step of separating the first solvent component from the first solvent-wet tailings. This separation is carried out by adding a second solvent to the first solvent-wet tailings, with the second solvent displacing the first solvent in the first solvent-wet tailings. This step results in the first solvent- wet tailings becoming second solvent-wet tailings, with the second-solvent wet tailings including a second solvent component. The method also include a step of separating the second solvent component from the second solvent- wet tailings to thereby form solvent-dry, stackable tailings. In some embodiments, a method for producing solvent-dry, stackable tailings includes a step of mixing a first material comprising bitumen with a first quantity of first solvent to form a first mixture. The method also includes a step of loading the first mixture into a vertical column having a top end and a bottom end. A step of injecting a second quantity of first solvent into the first mixture loaded in the vertical column at the top end of the vertical column is also included. The method further includes a step of collecting a bitumen-enriched solvent phase at the bottom end of the vertical column. The method also includes a step of injecting a first quantity of second solvent into the first mixture loaded in the vertical column at the top end of the vertical column. Additionally, the method includes the step of collecting a first solvent- enriched second solvent phase at the bottom end of the vertical column. The method also includes a step of discharging the first mixture from the vertical column. It is to be understood that the foregoing is a brief summary of various aspects of some disclosed embodiments. The scope of the disclosure need not therefore include all such aspects or address or solve all issues noted in the background above. In addition, there are other aspects of the disclosed embodiments that will become apparent as the specification proceeds.

The foregoing and other features, utilities, and advantages of the subject matter described herein will be apparent from the following more particular description of certain embodiments as illustrated in the accompanying drawings. In this regard, it is to be understood that the scope of the invention is to be determined by the claims as issued and not by whether given subject includes any or all features or aspects noted in this Summary or addresses any issues noted in the Background.

BRIEF DESCRIPTION OF THE DRAWINGS

The preferred and other embodiments are disclosed in association with the accompanying drawings in which: Figure 1 is a graph showing the minimum bitumen extraction rate as stipulated by the

Alberta Energy and Utilities Board for hot water extraction methods using naphtha-based froth treatment of various grades of ore sands and the actual bitumen extraction rates achieved using a hot water extraction method using paraffinic froth treatment for various grades of ore sands;

Figure 2 is a flow chart detailing a method for obtaining bitumen from bituminous material as disclosed herein; Figure 3 is a schematic diagram for a system and method for obtaining bitumen from bituminous material as disclosed herein;

Figure 4 is a schematic diagram for a system and method for obtaining bitumen from bituminous material as disclosed herein; Figure 5 is a schematic diagram for a system and method for obtaining bitumen from bituminous material as disclosed herein;

Figure 6 is the graph shown in Figure 1 and further including the bitumen extraction rates achieved for oils sands of various grades using the method described herein;

Figure 7 is a flow chart detailing a method for producing solvent-solvent-dry, stackable tailings as disclosed herein;

Figure 8 is a schematic diagram for a system and method for producing solvent-dry, stackable tailings as disclosed herein;

Figure 9 is a schematic diagram for a system and method for producing solvent-dry, stackable tailings as disclosed herein; Figure 10 is a flow chart detailing a method for producing solvent-dry, stackable tailings as disclosed herein;

Figure 11 is a schematic diagram for a system and method for producing solvent-dry, stackable tailings as disclosed herein; and Figure 12 is a photograph of solvent-dry, stackable tailings produced by the methods and systems described herein.

DETAILED DESCRIPTION

Before describing the details of the various embodiments herein, it should be appreciated that the terms "solvent," "a solvent" and "the solvent" include one or more than one individual solvent compound unless expressly indicated otherwise. Mixing solvents that include more than one individual solvent compound with other materials can include mixing the individual solvent compounds simultaneously or serially unless indicated otherwise. It should also be appreciated that the term "tar sands" includes oil sands. The separations described herein can be partial, substantial or complete separations unless indicated otherwise. All percentages recited herein are weight percentages unless indicated otherwise.

Tar sands are used throughout this disclosure as a representative material comprising bitumen. However, the methods disclosed herein are not limited to processing of tar sands. Any material comprising bitumen may be processed by the methods disclosed herein. With reference to Figure 2, a method for obtaining bitumen from bituminous materials includes a step 100 of mixing a material comprising bitumen with a first solvent to form a first mixture, a step 110 of separating a first quantity of bitumen-enriched solvent phase from the first mixture, and a step 120 of separating a second quantity of bitumen-enriched solvent phase from the first mixture. The step 100 of mixing a material comprising bitumen with a first solvent to form a first mixture represents a solvent extraction step (also sometimes referred to as dissolution, solvation, or leaching). Solvent extraction is a process of separating a substance from a material by dissolving the substance of the material in a liquid. In this situation, the material comprising bitumen is mixed with one or more solvents to dissolve bitumen in the solvent and thereby separate it from the other components of the material comprising bitumen (e.g., the mineral solids of tar sands).

The first solvent used in the mixing step can include a hydrocarbon solvent. Any suitable hydrocarbon solvent or mixture of hydrocarbon solvents that is capable of dissolving bitumen can be used. In some embodiments, the hydrocarbon solvent may be a hydrocarbon solvent that does not result in asphaltene precipitation. The hydrocarbon solvent or mixture of hydrocarbon solvents can be economical and relatively easy to handle and store. The hydrocarbon solvent or mixture of hydrocarbon solvents may also be generally compatible with refinery operations. In some embodiments, the first solvent may be a light aromatic solvent. The light aromatic solvent may be an aromatic compound having a boiling point temperature less than about 400 ⁰C at atmospheric pressure. In some embodiments, the light aromatic solvent used in the first mixing step may be an aromatic having a boiling point temperature in the range of from about 75⁰C to about 350 ⁰C at atmospheric pressure, and more specifically, in the range of from about 100 ⁰C to about 25O⁰C at atmospheric pressure. In some embodiments, the light aromatic solvent may be an aromatic having a boiling point temperature less than 200⁰C. It should be appreciated that the light aromatic solvent need not be 100% aromatic compounds. Instead, the light aromatic solvent may include a mixture of aromatic and non- aromatic compounds. For example, the first solvent can include greater than zero to about 100 wt% aromatic compounds, such as approximately 10 wt% to 100 wt% aromatic compounds, or approximately 20 wt% to 100 wt% aromatic compounds.

Any of a number of suitable aromatic compounds may be used as the first solvent. Examples of aromatic compounds that can be used as the first solvent include benzene, toluene, xylene, aromatic alcohols and combinations and derivatives thereof. The first solvent can also include compositions, such as kerosene, diesel (including biodiesel), light gas oil, light distillate (distillate having boiling point temperature in the range of from 140 ⁰C to 260 ⁰C), commercial aromatic solvents such as Solvesso 100, Solvesso 150, and Solvesso 200 (also known in the U.S.A. as Aromatic 100, 150, and 200, including mainly C₁₀-C₁₁ aromatics, and produced by ExxonMobil), and/or naphtha. In some embodiments, the first solvent may have a boiling point temperature of approximately 75 ⁰C to 375 ⁰C. Naphtha, for example, may be particularly effective at dissolving bitumen and may be generally compatible with refinery operations.

The material comprising bitumen used in the mixing step may be any material that includes bitumen. Exemplary materials comprising bitumen include, but are not limited to, tar sands, black shales, coal formations, and hydrocarbon sources contained in sandstones and carbonates. The material comprising bitumen may be obtained by any known methods for obtaining material comprising bitumen, such as by surface mining, underground mining, or any other in situ extraction methods, such as vapor extraction (Vapex), and steam assisted gravity drainage (SAGD) extraction.

In some embodiments, the material comprising bitumen may be low grade material comprising bitumen. Low grade material comprising bitumen may include any material having a bitumen content of less than about 10 wt%.

The aim of mixing the first solvent and the material comprising bitumen at 100 may be to have the first solvent fully penetrate the material comprising bitumen so that the entire bitumen content of the material comprising bitumen may be dissolved by the first solvent. Accordingly, any mixing process or mixing device known to those of ordinary skill in the art that will allow for the first solvent to disperse throughout the bituminous material and solvate the bitumen content of the bituminous material may be used.

The amount of time during which the first solvent and material comprising bitumen are mixed may be one factor that affects how comprehensively the first solvent dissolves the bitumen content of the material comprising bitumen. Generally speaking, the material may be mixed for any period of time. In some embodiments, mixing may be carried out for from 5 seconds to 60 minutes. With tar sand clumps of 3 inches or less, the mixing time may be limited to less than 30 minutes in order to avoid emulsion formation as discussed in greater detail below.

The manner in which the first solvent and material comprising bitumen are mixed may be another factor that affects how comprehensively the first solvent dissolves the bitumen content of the material comprising bitumen. Generally speaking, any mixing method may be used. In some embodiments, the mixing methods include the use of mixing devices, such as rotating blades or propellers. For example, the first solvent and the material comprising bitumen may be contained in a vessel having a mixing blade or propeller included therein. Engaging the mixing blade or propeller may mix the two materials together and help ensure that the first solvent fully penetrates the material comprising bitumen to dissolve the bitumen. In some embodiments, mixing may also be accomplished through the use of a rotating vessel in which the first solvent and material comprising bitumen may be contained. For example, the material comprising bitumen and the first solvent may be mixed by using a rotary drum plus trammel screen. The material comprising bitumen and first solvent may be added to the rotary drum at the same time to thereby produce a first mixture with barren over size material removed from the first mixture.

In some embodiments, the vessel used for mixing the first solvent and the material comprising bitumen need not have moving parts, such as a mixing blade or a rotating drum. Rather, mixing between the first solvent and the material comprising bitumen may be accomplished by the manner in which the materials are introduced into a vessel. For example, first solvent may be introduced into a vessel already containing material comprising bitumen at a relatively high velocity, thereby effectively causing agitation and mixing between the first solvent and the material comprising bitumen. In some embodiments, the first solvent need not be introduced at a relatively high velocity. Rather, the first solvent may be poured over material comprising bitumen packed in a vessel or in a heap on a pad and allowed to flow downwardly through the material comprising bitumen under the force of gravity or an externally applied force (such as overpressure or vacuum pressure). In this manner, the first solvent may fully penetrate the material comprising bitumen and achieve comprehensive dissolution of the bitumen without the need for agitation of the first solvent and material comprising bitumen.

The power used to mix the first solvent and the material comprising bitumen may also be controlled to ensure adequate bitumen dissolution while avoiding certain undesirable side effects. In some embodiments, the power used when mixing at 100 may be controlled in order to avoid the formation of water-solvent emulsions. Material comprising bitumen may include from about 2 wt% to about 10 wt% water, and excessive mixing with the first solvent can result in the formation of certain water-solvent emulsions that can be quite stable. However, by controlling the amount of power used when mixing (along with other factors such as the mixing time), the water content of the material comprising bitumen may stay associated with the non-bitumen components of the material comprising bitumen. Generally, any mixing regime that produces a Reynolds number in excess of 10,000 would likely result in the formation of certain water- solvent emulsions. Accordingly, in some embodiments, any mixing power that produces a first mixture having a Reynolds number less than 10,000 may be used. Such a result may be achieved by utilizing low intensity blending over an extended period of time, rather than blending at high intensities for shorter periods of time.

Additionally, using a mixing regime that results in a first mixture having a Reynolds number less than 10,000 may also avoid the undesirable breakdown or disintegration of any clay components of the material comprising bitumen. In some embodiments, the breakdown of clay components may be avoided by utilizing a mixing regime that produces a first mixture having a Reynolds number of less than 2,000 and with only laminar flow characteristics.

Mixing first solvent and material comprising bitumen at 100 may be performed at any suitable temperature and pressure. In certain embodiments, it may be desirable to perform the mixing at a reduced pressure to maintain the first solvent as a liquid during the mixing. In some embodiments, mixing may be performed at higher temperatures to allow for the use of a wider range of suitable first solvents (e.g. , aromatic solvents having a boiling point temperature higher than 400 ⁰C). The higher mixing temperature may be achieved by using first solvent recovered from the method described herein. Such first solvent may be recovered using a distillation process and therefore may have a high temperature (e.g., just below its boiling point temperature). Accordingly, when this first solvent is mixed with room temperature bituminous material, the mixing occurs at elevated temperature.

The step 100 of mixing a material comprising bitumen and a first solvent according to any of the above procedures and parameters can be performed as a continuous, batch, or semi- batch process. Continuous processing may typically be used in larger scale implementations. However, batch processing may result in more complete separations than continuous processing.

The amount of the first solvent added to the material comprising bitumen may be a sufficient amount to effectively dissolve at least a portion, or desirably all, of the bitumen in the material comprising bitumen. In some embodiments, the amount of the first solvent mixed with the material comprising bitumen may be approximately 0.5 to 6.0 times the amount of bitumen by volume contained in the material comprising bitumen, approximately 0.6 to 3.0 times the amount of bitumen by volume contained in the material comprising bitumen, or approximately 0.75 to 2.0 times the amount of bitumen by volume contained in the material comprising bitumen. The amount of first solvent mixed with the material comprising bitumen may be sufficient to fill up the open spaces between particles in the material comprising bitumen. In some embodiments, a minimum amount of solvent necessary to solvate most or all of the bitumen content of the material comprising bitumen may be added. In this manner, first solvent may be conserved and subsequent separation steps may be simplified (or eliminated altogether).

The mixing of the first solvent and the material comprising bitumen may generally result in the formation of a first mixture comprising a bitumen-enriched solvent phase. The bitumen-enriched solvent phase may include bitumen dissolved in the first solvent. In some embodiments, 80%, preferably 90%, and most preferably 95% or more of the bitumen in the material comprising bitumen may be dissolved in the first solvent and becomes part of the bitumen-enriched solvent phase.

In step 110, a first quantity of bitumen-enriched solvent phase may be separated from the first mixture. Any suitable method for separating the first quantity of bitumen-enriched solvent phase from the first mixture may be used. In some embodiments, the bitumen-enriched solvent phase may be separated from the first mixture by filtering or settling the first mixture.

Filtering of the first mixture may generally include any process wherein a filter medium is used to maintain the non-bitumen components of the material comprising bitumen on one side of the filter medium while allowing the bitumen-enriched solvent phase to collect on the opposite side of the filter medium by passing through the filter medium. Any type of filter medium may be used provided the filter medium is capable of preventing the flow of at least a portion of the non-bitumen components through the filter medium while allowing bitumen- enriched solvent phase to flow through the filter medium.

In some embodiments, the filtering process may involve a vacuum filter. The vacuum filter may be static (e.g., a pan filter) or continuous (e.g., a belt filter). The bitumen- enriched solvent phase may flow down through and out of the filter while the non-bitumen components of the material comprising bitumen remain in the filter.

In some embodiments, the filtering process may involve the use of a plate and frame- type filter press. The first mixture may be loaded in a frame chamber lined on either side with filter clothes. As the first mixture fills the frame chamber, the bitumen-enriched solvent phase may pass through the filter clothes and out of the frame chamber, leaving the non-bitumen components of the material comprising bitumen behind. Any plate and frame-type filter press known to those of ordinary skill in the art may be used. An exemplary plate and frame-type filter press suitable for use in this method is described in U.S. Pat. No. 4,222,873. Any of the filtration methods suitable for use in separating a first quantity of bitumen- enriched solvent phase from the first mixture may include the injection of gas over the first mixture to further promote separation. For example, in the case of filtering the first mixture via a plate and frame-type filter press, gas may be injected into the frame chamber after the frame chamber has been filled with the first mixture to further promote the separation of the bitumen- enriched solvent phase from non-bitumen components in the first mixture. Bitumen-enriched solvent phase liberated by the introduction of gas may then pass out of the filter chamber as part of the first quantity of bitumen-enriched solvent phase. Alternatively, the liberated bitumen- enriched solvent phase may remain in the first mixture, but will be repositioned so as to increase the likelihood that the liberated bitumen-enriched solvent phase is displaced from the first mixture during the separation of the second quantity of the bitumen-enriched solvent phase by the addition of a second quantity of first solvent to the first mixture. Any suitable gas may be used for promoting separation during filtration. In some embodiments, the gas may be any inert gas. In some embodiments, the gas may be nitrogen, carbon dioxide or steam. The amount of gas used with filtration is not limited. In the case of a plate and frame-type filter press, 1.8 m³ to 10.6 m³ of gas per ton of material comprising bitumen may be injected into the frame chamber. This is equivalent to a range of about 4.5 liters to 27 liters of gas per liter of material comprising bitumen. In some embodiments, 3.5 m³ of gas per ton of material comprising bitumen may be

j

used.

Settling of the first mixture may generally include any process wherein the heavier components of the first mixture are allowed to settle to the bottom of the first mixture under the influence of gravity or externally applied forces or a combination thereof, while the lighter components of the first mixture reside at the top of the first mixture and above of the heavier components of the mixture.

In some embodiments, settling of the first mixture may result in the non-bituminous components of the material comprising bitumen (e.g., mineral solids of tar sands) settling to the bottom of the first mixture while the bitumen-enriched solvent phase remains at the top of the first mixture and above the non-bituminous components of the material comprising bitumen. A first quantity of bitumen-enriched solvent phase may then be separated from the first mixture by any of a variety of procedures. In some embodiments, less than 100% of the bitumen-enriched solvent phase may be separated from the settled first mixture as a first quantity of bitumen- enriched solvent. Therefore, a second quantity of bitumen-enriched solvent phase may be removed from the settled first mixture via a second separation step described in greater detail below.

Settling may be carried out according to any known settling technique suitable for use with mixtures of solvents and materials comprising bitumen. In some embodiments, the settling technique includes storing the first mixture in a vessel for a period of time, during which gravity acts on the first mixture to cause the heavier components of the first mixture to settle to the bottom of the vessel. In some embodiments, pressure may be applied over the first mixture or a vacuum may be applied under the first mixture to promote the settling of the heavier components.

Settling may also be carried out for any suitable period of time. Generally speaking, settling carried out for longer periods of time will result in greater separation between the non- bituminous components of the material comprising bitumen and the bitumen-enriched solvent phase.

Any method of separating a first quantity of bitumen-enriched solvent phase from the settled first mixture may be used. In some embodiments, a first quantity of bitumen-enriched solvent phase is decanted from the top of the settled first mixture. Decanting may generally include pouring the top portion of the settled first mixture (i.e., bitumen-enriched solvent phase) out of a vessel in which the first mixture was settled while retaining the bottom portion of the settled mixture (i. e. , the non-bituminous components of the material comprising bitumen) in the settling vessel. Separation of a first quantity of bitumen-enriched solvent phase from a settled first mixture may also include skimming the first quantity of bitumen-enriched solvent phase from the top of the settled first mixture.

Settling of the first mixture may also result in the creation of a filter aid that may be used to further separate the bitumen-enriched solvent phase from the non-bituminous components of the first mixture. During settling, the heavier components may settle to the bottom of the first mixture and form a porous layer that may serves as a filter aid. That is to say, liquids may pass through the porous layer/filter aid and any solid particulate contained in the liquid may be filtered out of the liquid as it passes through the porous layer/filter aid. Therefore, to the extent that any non-bituminous material is still contained in the bitumen-enriched solvent phase after settling, such non-bituminous material may be filtered out of the bitumen-enriched solvent phase by filtering the bitumen-enriched solvent phase through the porous layer/filter aid formed during settling. Additionally, after the bitumen-enriched solvent phase has been separated from the porous layer/filter aid, further wash fluid (e.g., additional first solvent) may be passed through the porous layer to remove any residual amounts of bitumen that may not have been dissolved during the mixing step 100.

Any of the above described separation methods can be performed as continuous, batch, or semi-batch processes. Continuous processing may typically be used in larger scale implementations. However, batch processing may result in more complete separations than continuous processing.

The amount of bitumen-enriched solvent phase separated from the first mixture to make up the first quantity of bitumen-enriched solvent phase is not limited. In some embodiments, the first quantity of bitumen-enriched solvent phase may be equal to from about

5% to about 75 % of the total amount of bitumen-enriched solvent phase included in the first mixture.

As noted above, the composition of the bitumen-enriched solvent phase may generally include bitumen and first solvent. In some embodiments, the first quantity of bitumen- enriched solvent phase removed from the first mixture may include from about 5 wt% to about 25 wt% of bitumen and from about 75 wt% to about 95 wt% of the first solvent. The bitumen- enriched solvent phase may include little or no non-bitumen components of the material comprising bitumen (e.g. , mineral solids).

In step 120, a second quantity of bitumen-enriched solvent phase may be separated from the first mixture. The addition of a second solvent to the first mixture may displace the second quantity bitumen-enriched solvent phase that is still present in the first mixture after the separation step 110 and thereby force the second quantity of bitumen-enriched solvent phase out of the first mixture. Some of the second solvent may remain in the first mixture, but little to no bitumen-enriched solvent phase may remain. The second solvent may be the same class of first solvent (i.e., a light aromatic hydrocarbon) or the exact same first solvent as used when mixing first solvent with the material comprising bitumen. Alternatively, the second solvent may be a different solvent from the first solvent (i.e., a non-light aromatic solvent). In some embodiments where a second solvent used is different from the first solvent, the second solvent may be a polar solvent. The polar solvent can be any suitable polar solvent that is capable of displacing the first solvent. In some embodiments, the polar solvent may be an oxygenated hydrocarbon. Oxygenated hydrocarbons may include any hydrocarbons having an oxygenated functional group. Oxygenated hydrocarbons may include alcohols, ketones and ethers. Oxygenated hydrocarbons as used in the present application do not include alcohol ethers or glycol ethers.

Suitable alcohols for use as the polar solvent may include methanol, ethanol, propanol, and butanol. The alcohol may be a primary (e.g., ethanol), secondary (e.g., isopropyl alcohol) or tertiary alcohol (e.g., tert-butyl alcohol). As noted above, the polar solvent may also be a ketone. Generally, ketones are a type of compound that contains a carbonyl group (C=O) bonded to two other carbon atoms in the form: Rl(C0)R2. Neither of the substituents Rl and R2 may be equal to hydrogen (H) (which would make the compound an aldehyde). A carbonyl carbon bonded to two carbon atoms distinguishes ketones from carboxylic acids, aldehydes, esters, amides, and other oxygen- containing compounds. The double-bond of the carbonyl group distinguishes ketones from alcohols and ethers. The simplest ketone is acetone, CH3-CO-CH3 (systematically named propanone).

In some embodiments where the second solvent used is different from the first solvent, the second solvent can include one or more volatile hydrocarbon solvents. Volatile hydrocarbon solvents may generally include hydrocarbons having a boiling point temperature between about -20 ⁰C and 150 ⁰C. Volatile hydrocarbon solvents may also include aliphatic compounds that are capable of solvating bitumen and/or the first solvent. Suitable aliphatic compounds can include compounds such as alkanes or alkenes. Any of these aliphatic compounds can be functionalized or non-functionalized. In some embodiments, the second solvent may include one or more aliphatic hydrocarbons having 3 to 9 carbon atoms. In some embodiments, the second solvent may include aliphatic hydrocarbons having no more than 9 carbon atoms. The second solvent may also include lower carbon paraffins, such as cyclo- and iso-paraffins having 3 to 9 carbon atoms. The second solvent may include one or more of any of the following compounds: methane, ethane, propane, butane, and/or pentane, alkene equivalents of these compounds and/or combinations and derivatives thereof.

In some embodiments, the second solvent may include liquefied petroleum gas (LPG). The term "liquefied petroleum gas" is used broadly herein to refer to any hydrocarbon gas (hydrocarbons that are gases at ambient temperature (25 ⁰C) and pressure (1 arm)) that has been compressed to form a liquid. Preferably, the LPG may be primarily or even entirely propane or predominantly or entirely butane. However, other LPG formulations are contemplated including commercially available formulations. The composition of common commercial LPG can vary depending on the time of the year, geographical location, etc. Commercial LPG is a natural derivative of both natural gas and crude oil. Often, LPG is a mixture of propane and butane (n-butane and/or i-butane) with small amounts of propylene and butylene (any one or combination of the four isomers). A powerful odorant such as ethanethiol is typically added to make it easy to detect leaks. Commercial LPG also often contains very small amounts of lighter hydrocarbons, such as ethane and ethylene, and heavier hydrocarbons such as pentane.

Three examples of commercial LPG are shown below in Table 1 : Table 1 - Examples of Commercially Available LPG

LPG may be stored and transported under pressure to maintain the hydrocarbons as Hquids. In some embodiments, LPG may have a boiling point at atmospheric pressure of approximately -80 °C to 10 ⁰C, desirably, approximately -55 °C to 5 ⁰C, or, suitably, approximately -35 ⁰C to -5 ⁰C.

Any suitable amount of second solvent may be added to the first mixture in order to displace the second quantity of bitumen-enriched solvent phase. In some embodiments, the second solvent may be added to the first mixture in an amount of from about 10% to about 400% of the amount of first solvent mixed with the material comprising bitumen during step 100.

The second quantity of bitumen-enriched solvent phase displaced from the first mixture may include predominantly bitumen and first solvent. In some embodiments, the second quantity of bitumen-enriched solvent phase may include from about 5 wt% to about 50 wt% bitumen and from about 50 wt% to about 95 wt% first solvent. Little to no non-bitumen components of the material comprising bitumen may be present in the second quantity of bitumen-enriched solvent phase.

After removal of the second quantity of bitumen-enriched solvent phase, the first mixture may include little or no bitumen. In some embodiments, the first mixture may include from 0 wt% to about 2 wt% bitumen, from about 2 wt% to about 15 wt% first solvent, and from about 83 wt% to about 98 wt% non-bitumen components after separation of the second quantity of bitumen-enriched solvent phase.

Any suitable method for adding a second solvent to the first mixture may be used to separate the second quantity bitumen-enriched solvent phase from the first mixture. In some embodiments, the second solvent may be added to the first mixture as part of a countercurrent washing process. In some embodiments, the second solvent may be added to a first mixture loaded in a plate and frame-type filter press. In some embodiments, the second solvent may be added to a first mixture loaded in a vertical column.

When a countercurrent process is used to add the second solvent, the process may generally include moving the first mixture in one direction while passing the second solvent through the first solvent-wet tailings in an opposite direction. For example, the first mixture may be loaded at the bottom of a screw classifier conveyor positioned at an incline, while the second solvent may be introduced at the top of the screw classifier conveyor. An exemplary screw classifier conveyor suitable for use in this method is described in U.S. Pat. No. 2,666,242. As the screw classifier conveyor moves the first mixture upwardly, the second solvent may flow down the inclined screw classifier conveyor and pass through the first mixture. The second solvent may displace a second quantity of bitumen-enriched solvent phase contained in the first mixture, thereby "washing" the second quantity of bitumen-enriched solvent from the first mixture. Separation of the second quantity of bitumen-enriched solvent phase and the first mixture may naturally occur based on the configuration of the screw classifier conveyor, with the predominantly liquid bitumen-enriched solvent phase collecting at one end of the washing unit and the predominantly solid first mixture collecting at the opposite end of the washing unit. For example, when an inclined screw classifier conveyor is used, the second quantity of bitumen- enriched solvent phase may collect at the bottom of the screw classifier conveyor, while the first mixture may collect at the top of the screw classifier conveyor. The countercurrent process may include multiple stages. For example, after a first pass of second solvent through the first mixture, the resulting second quantity of bitumen- enriched solvent phase may be passed through the first mixture several more times. Alternatively, additional quantities of fresh second solvent may be passed through the first mixture one or more times. In this manner, the second quantity of bitumen-enriched solvent phase or fresh quantities of second solvent may become progressively more enriched with bitumen after each stage and the first mixture may lose progressively more bitumen after each stage.

When a plate and frame-type filter press is used to separate the second quantity of bitumen-enriched solvent phase from the first mixture through the addition of a second solvent, the process may generally include injecting the second solvent into the first mixture that is loaded in the frame chamber of the plate and frame-type filter press.

Any suitable type of plate and frame-type filter press may be used. The plate and frame-type filter press used for the separation of the second quantity of bitumen-enriched solvent phase may be a separate plate and frame-type filter press from the plate and frame-type filter press used to separate the first quantity of bitumen-enriched solvent phase from the first mixture, or may be the same plate and frame-type filter press used to separate the first quantity of bitumen-enriched solvent phase from the first mixture. When the same plate and frame-type filter press is used, the method may include adding the second solvent to the first mixture still loaded in the frame chamber after separation of the first quantity of bitumen-enriched solvent phase. In other words, the method need not include a step of removing the first mixture from the plate and frame-type filter press before injecting the second solvent.

The second solvent may be pumped into the plate and frame-type filter press where it may displace the second quantity of bitumen-enriched solvent phase from the first mixture located in the frame chambers. The second quantity of bitumen-enriched solvent phase displaced out of the first mixture may migrate through the filter clothes lining the frame chamber. Some of the second solvent injected into the first mixture may also migrate out of the frame chamber with the second quantity of bitumen-enriched solvent phase, but some of the second solvent may remain in the first mixture loaded in the frame chamber. In some embodiments, 95% or more of the bitumen-enriched solvent phase remaining in the first mixture may be displaced by the addition of the second solvent.

Gas may also be injected into the frame chamber prior to or following the injection of the second solvent into the first mixture. Injecting gas into the frame chamber may promote the separation of the bitumen-enriched solvent phase from mineral solids in the first mixture. By liberating the bitumen-enriched solvent phase in this manner, the bitumen-enriched solvent phase may be more likely to be displaced from the first mixture upon the addition of the second solvent. The process for adding gas may be identical to the method described above with respect to addition of gas as part of separating the first quantity of bitumen-enriched solvent phase from the first mixture in a plate and frame-type filter press. When a vertical column is used to separate the second quantity of bitumen-enriched solvent, the process may generally include loading the first mixture in a vertical column and adding the second solvent to the first mixture from the top end of the vertical column. The second solvent may flow down through the vertical column, displacing the bitumen-enriched solvent phase from the first mixture loaded in the vertical column until a second quantity of bitumen-enriched solvent phase eventually exits the vertical column and the bottom end of the vertical column.

Any method of loading the first mixture in the vertical column may be used. First mixture may be poured into the vertical column or, when an appropriate first mixture viscosity is obtained, the first mixture may be pumped into the vertical column. The first mixture may be loaded in the vertical column by introducing the first mixture into the column at the top end of the vertical column. The bottom end of the vertical column may be blocked, such as by a removable plug or valve or by virtue of the bottom end of the vertical column resting against the floor. In some embodiments, a metal filter screen at the bottom end of the vertical column may be used to maintain the first mixture in the vertical column. As such, introducing the first mixture at the top end of the vertical column may fill the vertical column with first mixture. The amount of first mixture loaded in the vertical column may be such that the first mixture substantially fills the vertical column with first mixture. In some embodiments, first mixture may be added to the vertical column to occupy 90% or more of the volume of the vertical column. In some embodiments, the first mixture may not be filled to the top of the vertical column so that room is provided to inject the second quantity of the first solvent. As noted above, the column may have a generally vertical orientation. The vertical orientation may include aligning the column substantially perpendicular to the ground, but also may include orientations where the column forms angles less than 90° with the ground. The column may generally be oriented at any angle that results in gravity aiding the flow of the second quantity of first solvent from one end of the column to the other. In some embodiments, the column may be oriented at an angle anywhere within the range of from about 1° to 90° with the ground. In a preferred embodiment, the column may be oriented at an angle anywhere within the range of from about 15° to 90° with the ground.

The material of the vertical column is also not limited. Any material that will hold the first mixture within the vertical column may be used. The material may also preferably be a non-porous material such that liquids injected into the vertical column may only exit the column from one of the ends of the vertical column. The material may be a corrosive resistant material so as to withstand the potentially corrosive components of the first mixture loaded in the column as well as any potentially corrosive materials injected into the vertical column.

The shape of the vertical column is not limited to a specific configuration. Generally speaking, the vertical column may have two ends opposite one another, designated a top end and a bottom end. The cross-section of the vertical column may be any shape, such as a circle, oval, square or the like. The cross-section of the vertical column may change along the height of the column, including both the shape and size of the vertical column cross-section. The vertical column may be a straight line vertical column having no bends or curves along the height of the vertical column. Alternatively, the vertical column may include one or more bends or curves. Any dimensions may be used for the vertical column, including the height, inner cross sectional diameter and outer cross sectional diameter of the vertical column. In some embodiments, the ratio of height to inner cross sectional diameter may range from 0.5:1 to 15:1.

Once the first mixture is loaded in the vertical column, the second can be added into the vertical column. The second solvent may be added into the vertical column at the top end of the column such that the second solvent flows down and through the first mixture loaded in the column. The second solvent may be added into the vertical column by any suitable method. In some embodiments, the second solvent may be poured into the vertical column at the top end and allowed to flow down through the first mixture loaded therein under the influence of gravity. External forces may also be applied to the vertical column to assist the flow of the second solvent through the vertical column.

The amount of second solvent added to the first mixture loaded in the vertical column is not limited. The amount may preferably be enough second solvent to displace most or all of the remaining bitumen-enriched solvent in the first mixture. In some embodiments, the amount of second solvent added may be from about 1.25 to about 2.25 times the amount of bitumen by volume in the original material comprising bitumen.

Upon injection into the first mixture, the second solvent may flow downwardly through the height of the column via small void spaces in the first mixture. The second solvent may flow downwardly through the force of gravity or by an external force applied to the vertical column. Examples of external forces applied include the application of pressure from the top of the vertical column or the application of suction at the bottom of the vertical column. The second first solvent may typically travel the flow of least resistance through the first mixture. As the second solvent flows downwardly through the first mixture, bitumen-enriched solvent phase may be displaced out of the first mixture.

In some embodiments, the addition of second solvent may be carried out under flooded conditions. In other words, more second solvent may be added to the top of the vertical column than what flows down through the first mixture, thereby creating a head of solvent at the top of the vertical column and creating a "plug flow" condition through the column.

The bitumen-enriched solvent that is being displaced by the second solvent may flow downwardly through the height of the vertical column and exit the vertical column where it may be collected for further use and processing. In some embodiments, the bitumen-enriched solvent may include from about 10 wt % to about 60 wt% bitumen and from about 40 wt% to about 90 wt% second solvent. Minor amounts of non-bitumen material may also be included in the bitumen-enriched solvent phase. In some embodiments, 95 % or more of the bitumen-enriched solvent phase may be removed from the first mixture through the addition of the second quantity of first solvent.

Any method of collecting the second quantity of bitumen-enriched solvent may be used, such as by providing a collection vessel at the bottom end of the vertical column. The bottom end of the vertical column may include a metal filter screen having a mesh size that does not permit first mixture to pass through but which does allow for the second quantity of bitumen- enriched solvent to pass through and collect in a collection vessel located under the screen. Collection of the second quantity of bitumen-enriched solvent may be carried out for any suitable period of time. In some embodiments, collection is carried out for 2 to 30 minutes.

The method may include further additions of second solvent to displace any remaining bitumen-enriched solvent phase from the first mixture loaded in the vertical column. In other words, after injecting a first quantity of second solvent and collecting the bitumen- enriched solvent at the bottom of the vertical column, a second quantity of second solvent may be added to the vertical column to displace additional bitumen-enriched solvent from the first mixture. Repeating these steps may increase the overall removal rate of bitumen-enriched solvent phase from the first mixture. In some embodiments, the use of multiple second solvent injection steps may result in the removal of 95% or more of the bitumen-enriched solvent phase in the first mixture.

The second quantity of bitumen-enriched solvent phase collected according to any of the above-described methods may be combined with the first quantity of bitumen-enriched solvent phase prior to any further processing conducted on the bitumen-enriched solvent phase. The combined bitumen-enriched solvent phase may undergo further processing to, for example, isolate the bitumen from the solvent and/or upgrade the bitumen. Isolation of the bitumen content may be carried out according to any method know to those of ordinary skill in the art, including heating the bitumen-enriched solvent phase to a temperature above the boiling point temperature of the first solvent in order to evaporate the first solvent. Any evaporated solvent may be captured and condensed for further use. Upgrading of the bitumen may comprise any processing that generally produces a stable liquid (i.e., synthetic crude oil) and any subsequent refinement of synthetic crude oil into petroleum products. The process of upgrading bitumen to synthetic crude oil may include any processes known to those of ordinary skill in the art, such as heating or cracking the bitumen to produce synthetic crude. The process of refining synthetic crude may also include any processes known to those of ordinary skill in the art, such as distillation, hydrocracking, hydrotreating and coking. They petroleum products produced by the upgrading are not limited, any may include petroleum, diesel fuel, asphalt base, heating oil, kerosene, and liquefied petroleum gas.

Optionally, the method may include further steps to remove any second solvent remaining in the first mixture after the second quantity of bitumen-enriched solvent phase has been displaced. In some embodiments, the removal of the second solvent may only take place after most or all of the bitumen in the first mixture has been removed from the first mixture (e.g., by removing most or all the bitumen-enriched solvent phase from the first mixture).

In embodiments where the second solvent is a light aromatic solvent, the second solvent may be removed by displacing the second solvent from the first mixture through the addition of a third solvent to the first mixture. The third solvent can be any suitable solvent that is useful for displacing the second solvent from the first mixture. In some embodiments, the third solvent may have a lower vapor pressure than the second solvent to enhance removal of the third solvent in subsequent processing steps. In some embodiments, the third solvent may be a hydrocarbon solvent. Any suitable hydrocarbon solvent or mixture of hydrocarbon solvents that is capable of displacing the first solvent may be used. The hydrocarbon solvent or mixture of hydrocarbon solvents can be economical and relatively easy to handle and store. The hydrocarbon solvent or mixture of hydrocarbon solvents may also be generally compatible with refinery operations.

In some embodiments, the third hydrocarbon solvent can include one or more volatile hydrocarbon solvents. The volatile hydrocarbon solvent may be identical to the volatile hydrocarbon solvent described above in greater detail.

Adding third solvent to the first mixture may be carried out in any suitable manner that results in second solvent displacement from the first mixture. In some embodiments, third solvent may be added to the first mixture in an identical manner to any of the methods described above for the addition of the second solvent to the mixture. For example, the third solvent may be added to a first mixture loaded in a plate and frame-type filter press, the third solvent may be added to the first mixture in a countercurrent washing process, or the third solvent may be added to the first mixture loaded in a vertical column.

The amount of the third solvent added to the first mixture may be sufficient to effectively displace at least a portion, or desirably all, of the second solvent remaining in the first mixture after separation of the second quantity of bitumen-enriched solvent phase. The amount of third solvent added to the first mixture may be approximately 0.5 to 1 times the amount of bitumen by volume originally contained in the material comprising bitumen.

As with previously described separation steps, separation of the second solvent from the first mixture may be preceded or followed by applying pressurized gas over the first mixture. Applying a pressurized gas over the first mixture may facilitate the separation of the second solvent from the non-bitumen components of the first mixture. The liberated second solvent can then be removed from the first mixture upon the addition of the third solvent to the first mixture. Any suitable gas may be used. In some embodiments, the gas may be an inert gas. In some embodiments, the gas may be nitrogen, carbon dioxide or steam. The gas may also be added over the first mixture in any suitable amount. In some embodiments, 1.8 m³ to 10.6 m³ of gas per ton of material comprising bitumen may be used. This is equivalent to a range of about 4.5 liters to 27 liters of gas per liter of material comprising bitumen. In some embodiments, 3.5 m³ of gas per ton of material comprising bitumen may be used.

In some embodiments, the addition of third solvent to the first mixture may result in the removal of 95% or more of the second solvent in the first mixture. The second solvent may leave the first mixture as a mixture of second solvent and third solvent. The second solvent-third solvent mixture may include from about 5 wt% to about 50 wt% second solvent and from about

50 wt% to about 95 wt% third solvent.

The removal of the second solvent from the first mixture through the addition of third solvent may result in a quantity of third solvent not passing all the way through the first mixture. In some embodiments, the first mixture may include from about 70 wt % to about 95 wt% non- bitumen components and from about 5 wt% to about 30 wt% third solvent after removal of the first solvent from the first mixture. As such, the first mixture may undergo further processing to remove the third solvent produce solvent-dry tailings. Any manner of removing third solvent from the first mixture may be used. In some embodiments the third solvent may be removed from the first mixture by drying, flashing or heating the first mixture. In this manner, the third solvent may evaporate from the first mixture and leave behind solvent-dry tailings. Separation of the third solvent from the first mixture may result in 95% or more of the third solvent in the first mixture being removed.

When the third solvent is a volatile hydrocarbon, the energy required to remove the third solvent may be minimal. In some embodiments, the third solvent may be removed from the solvent-wet tailings at room temperature.

Removal of the third solvent from the first mixture may also result in the separation of any second solvent still present in the first mixture. Separation of the second solvent may occur together with the separation of the third solvent, such as by heating or flashing the solvent wet tailings in a manner causing both solvents to evaporate from the first mixture. Alternatively, the separation may be incremental, wherein the flashing or heating is carried out to start with at conditions that will cause only the third solvent to evaporate, followed by adjusting the conditions to cause the evaporation of the second solvents. Any solvent removed from the first mixture may be recovered for further use, such as by sending the evaporated solvents to stills. The solvent-dry tailings resulting from removal of the third solvent from the first mixture may generally include inorganic solids, such as sand and clay, water, and little to no second and third solvent. As used herein, the term "solvent-dry" means containing less than 0.1 wt% total solvent. The water content of the solvent-dry tailings may range from about 2 wt% to about 15 wt%. This range of water content may create a damp tailings that will not produce dust when transporting or depositing the tailings. This range of water content may also provide a stackable tailings that will not flow like dry sand, and therefore has the ability to be retained within an area without the need for retaining structures (e.g., a tailings pond). This range of water content may also provide tailings that are not so wet as to be sludge-like or liquid-like.

In embodiments where the second solvent is a volatile hydrocarbon solvent, the second solvent may be removed by drying, flashing or heating the first mixture. Removal of the second solvent may be accomplished by any of the procedure with minimal energy input due to the volatility of the second solvent. The second solvent may evaporate from the first mixture and leave behind solvenx-dry tailings as described above. Separation of the second solvent from the first mixture may result in 95% or more of the second solvent in the first mixture being removed.

With reference to Figure 3, a system 200 for carrying out the above-described method may include a mixer 205 for mixing material comprising bitumen 210 and a first solvent 215. Any suitable mixing vessel may be used, including a mixing vessel that operates under pressure in order to maintain the first solvent as a liquid. A first mixture 220 is formed by the mixing of the material comprising bitumen 210 and the first solvent 215 in the mixer 205. The first mixture 220 contains bitumen-enriched solvent phase. The first mixture 220 is transported to a first separation unit 225 where a first quantity of bitumen-enriched solvent phase 230 is separated from the first mixture 220. Any filtration, or settling separation unit suitable for separating the first quantity of bitumen-enriched solvent phase 230 from the first mixture 220 may be used. Gas 285-1 may be pumped into the first separation unit 225 to promote separation of bitumen-enriched solvent phase from the non- bitumen components of the material comprising bitumen. When gas 285-1 is pumped into first separation unit 225, the spent gas may also exit the first separation unit 225 with the first quantity of bitumen-enriched solvent phase 230. Because the gas does not dissolve in either the bitumen or the first solvent of the first mixture 220, the gas exits with the first quantity of bitumen-enriched solvent phase 230 and does not require any additional separation processing.

The first mixture 220' remaining after the separation of the first quantity of bitumen- enriched solvent phase 230 is transported to a second separation unit 240 where a second solvent

245 is added to the first mixture 220' in order to separate a second quantity of bitumen-enriched solvent phase 255 from the first mixture 220'. Any separation unit suitable for separating the second quantity of bitumen enriched solvent 255 from the first mixture 220' through the addition of a second solvent 245 may be used. Gas 285-2 may be pumped into the second separation unit 240 to promote separation of the bitumen-enriched solvent phase from the non-bitumen components of the first mixture 220'. In some embodiments, separation units 225 and 240 may be one in the same unit to avoid the need to transport first mixture 220'.

With reference to Figure 4, a version of the system used to carry out the method of the above embodiment wherein countercurrent washing is shown. Pre-mixture 310 includes material comprising bitumen mixed with first solvent to cause bitumen to dissolve in the first solvent. The pre-mixture 310 is transported to a first separation unit 315 where a first quantity of bitumen-enriched solvent phase 320 is separated from the pre-mixture 310. The first separation unit 315 may be any type of filtering, settling or drainage separation unit suitable for separating a first quantity of bitumen-enriched solvent phase 320 from the pre-mixture 310. The pre-mixture 310' remaining after the separation of the first quantity of bitumen- enriched solvent phase 320 is transported to a washing unit 325. The pre-mixture 310' moves in a first direction and a second solvent 330 moves in an opposite direction towards the pre-mixture 310'. The pre-mixture 310' mixes with the second solvent 330, during which a second quantity of bitumen-enriched solvent phase 335 is displaced from the pre-mixture 310' by the second solvent 330. The second quantity of bitumen-enriched solvent phase 335 and the first mixture 310" separate due to the countercurrent configuration of the washing unit 325. In some embodiments, a portion of the bitumen enriched solvent phase 335 may be mixed with material comprising bitumen to form pre-mixture 310.

With reference to Figure 5, another version of the system used to carry out the method of this embodiment where a vertical column is utilized is shown. A mixing vessel 405 is provided for mixing material comprising bitumen 410 with a first solvent 415 to form a first mixture 420. Any type of mixing vessel may be used to mix the material comprising bitumen

410 and the first solvent 415.

The first mixture 420 is then loaded in the vertical column 425. Figure 4 depicts the first mixture 420 being loaded in the top end of the vertical column 425, but the first mixture 420 can also be loaded from the bottom end of the vertical column 425 or from the side of the vertical column 425. Once the first mixture 420 is loaded in the vertical column 425, a first quantity of bitumen-enriched solvent phase 430 is filtered out of the vertical column. Filtering of the first quantity of bitumen-enriched solvent phase 430 can be under the force of gravity or with the aid of a gas 435. The first quantity of bitumen-enriched solvent phase 430 is collected at the bottom end of the vertical column 425. Any gas 435 injected into the first mixture 420 may also exit out of the vertical column. A second solvent 440 is injected into the top end of the vertical column 425. The second solvent 440 flows down the height of the vertical column 425, displacing a second quantity of bitumen-enriched solvent phase 445 from the first mixture 420. The non-bitumen components of the material comprising bitumen remain in a packed condition in the vertical column 425 as the second solvent 440 passes through the first mixture 425 and displaces the second quantity of bitumen-enriched solvent phase 445. The second quantity of bitumen- enriched solvent phase 445 exits the bottom end of the vertical column 425 along with any of the second solvent 440 that travels all the way through the vertical column 425.

As described in greater detail in co-pending U.S. Application Nos. 12/041,554 and 11/249,234, further processing may be performed on the components produced by the methods described above. For example, the first quantity and second quantity of bitumen-enriched solvent phase may be processed to separate the bitumen therefrom. Furthermore, as described in co-pending application No. 12/509,298, herein incorporated by reference, any bitumen obtained from the above-described methods or from further processing of the bitumen-enriched solvent phases produced by the above-described processes may be cracked in a nozzle reactor (with or without deasphalting) to produce light hydrocarbon distillate. The light hydrocarbon distillate may then be used as a first solvent to extract bitumen from material comprising bitumen. In one example, the light hydrocarbon distillate produced may be recycled within the same process to initiate extraction of bitumen from further material comprising bitumen. Additionally, any solvent separated or removed from a mixture may be recovered and reused in the process. For example, where the bitumen-enriched solvent phases are separated into bitumen and first solvent, the first solvent may be recovered and reused in the process. Separation of the solvents may be accomplished by any know method, such as through the use of stills.

In some embodiments, tailings typically produced by bitumen extraction methods are processed to remove most, if not substantially all, of the solvent from the tailings so that the solvents can be considered "solvent-dry". With reference to FIG. 7, one embodiment of a method for producing solvent-dry, stackable tailings may include mixing 1000 a first quantity of material comprising bitumen with a first solvent to form a first mixture, separating 1100 a bitumen-enriched solvent phase from the first mixture to thereby form first solvent-wet tailings, separating 1200 first solvent from the first solvent- wet tailings by adding second solvent to the first solvent- wet tailings and thereby forming second solvent- wet tailings, and separating 1300 second solvent from the second solvent-wet tailings to thereby form solvent-dry, stackable tailings.

The mixing step 1000 is similar or identical to the mixing step 100 described in greater detail above. The mixing step 1000 is a solvent extraction step where material comprising bitumen and a hydrocarbon solvent are mixed together to extract the bitumen content from the remaining materials of the material comprising bitumen. The hydrocarbon solvent and the material comprising bitumen used can be similar or identical to the hydrocarbon solvent and material comprising bitumen described in greater detail above.

The material comprising bitumen and the first solvent may be mixed by any suitable manner for mixing two materials for any suitable period of time. The mixing of the material comprising bitumen and the first solvent is preferably carried out to the point of dissolving most, if not all, of the bitumen contained in the material comprising bitumen. In some embodiments, the material comprising bitumen and the first solvent may be mixed in a vessel to dissolve the bitumen and form the first mixture. The vessel can be selectively opened or closed. The vessel used for mixing may also contain mechanisms for stirring and mixing solvent and material comprising bitumen to further promote dissolution of the bitumen in the first solvent. For example, powered mixing devices such as a rotating blade may be provided to mix the contents of the vessel. In another example, the vessel itself may be rotated to cause mixing between the material comprising bitumen and the first solvent.

In certain embodiments, material comprising bitumen and the first solvent may be mixed by virtue of the manner in which the material comprising bitumen and the first solvent are introduced into the vessel. That is to say, the first solvent may be introduced into a vessel already containing material comprising bitumen at a high velocity, thereby effectively agitating and mixing the contents of the vessel. Conversely, the material comprising bitumen may be introduced into a vessel already containing first solvent. The amount of the first solvent added to the material comprising bitumen may be a sufficient amount to effectively dissolve at least a portion, or desirably all, of the bitumen in the material comprising bitumen. In some embodiments, the amount of the first solvent mixed with the material comprising bitumen may be approximately 0.5 to 3.0 times the amount of bitumen by volume contained in the material comprising bitumen, approximately 0.6 to 2.0 times the amount of the bitumen by volume contained in the material comprising bitumen, or approximately 0.75 to 1.5 times the amount of bitumen by volume contained in the material comprising bitumen.

It should be noted that the ratio of the first solvent to bitumen may be affected by the amount of bitumen in the material comprising bitumen. For example, more solvent may be required for lower grade tars sands ore (e.g., 6 wt% bitumen) than for higher grade tar sands ore (e.g., greater than 12 wt% bitumen).

The first mixture of the first solvent and the material comprising bitumen may generally result in the formation of a bitumen-enriched solvent phase within the first mixture, with the majority of the bitumen from the material comprising bitumen dissolved in the bitumen- enriched solvent phase. In some embodiments, 90%, preferably 95%, and most preferably 99% or more of the bitumen in the material comprising bitumen is dissolved in the first solvent and becomes part of the bitumen-enriched solvent phase.

The bitumen-enriched solvent phase may be separated 1100 from the first mixture. Separation of the bitumen-enriched solvent phase from the first mixture may result in the first mixture becoming first solvent-wet tailings. Any suitable process for separating the bitumen- enriched solvent phase from the first mixture may be used, such as by filtering (including filtration via an automatic pressure filter), settling and decanting, or by gravity or gas overpressure drainage.

In some embodiments, the bitumen-enriched solvent phase removed from the first mixture may include from about 5 wt% to about 50 wt% of bitumen and from about 50 wt% to about 95 wt% of the first solvent. The bitumen-enriched solvent phase may include little or no non-bitumen components of the material comprising bitumen (e.g., mineral solids). The first solvent-wet tailings created by removing the bitumen-enriched solvent phase from the first mixture may include from about 75 wt% to about 95 wt% non-bitumen components of the material comprising bitumen and from about 5 wt% to about 25 wt% first solvent. The first solvent component of the first solvent-wet tailings represents first solvent mixed with the material comprising bitumen but which is not removed from the first mixture during separation step 110. This first solvent component of the first solvent- wet tailings may have bitumen dissolved therein. Accordingly, in some embodiments, the first solvent-wet tailings may include from about 50 wt% to about 99 wt% of bitumen.

The vessel for mixing mentioned previously may function as both the mixer and a separator for separating the bitumen-enriched solvent phase from the first mixture. Alternatively, separate vessels can be used for mixing and separating, wherein the first mixture is transported from the mixing vessel to a separation vessel. In some embodiments, the vessel may be divided into sections. One section may be used to mix the material comprising bitumen and the first solvent and another section may be used to separate the bitumen-enriched solvent phase from the first mixture.

The separation of the bitumen-enriched solvent phase from the first mixture can be performed as a continuous, batch, or semi-batch process. Continuous processing may typically be used in larger scale implementations. However, batch processing may result in more complete separations than continuous processing. Separation of the bitumen-enriched solvent phase from the first mixture by any of the above-described methods may be preceded or followed by applying pressurized gas over the first mixture. Applying a pressurized gas over the first mixture may facilitate the separation of the bitumen-enriched solvent phase from the non-bitumen components of the first solvent-wet tailings. Liberated bitumen-enriched solvent phase can then be removed by applying additional first solvent to the first solvent-wet tailings as described in greater detail below. The addition of additional first solvent may also displace the liberated bitumen-enriched solvent phase from the first solvent- wet tailings by providing a driving force across a filtration element (i.e., the non- bituminous components of the material comprising bitumen). Any suitable gas may be used. In some embodiments, the gas may be nitrogen, carbon dioxide or steam. The gas may also be added over the first mixture in any suitable amount. In some embodiments, 62.5 ft³ to 375 ft³ of gas per ton of material comprising bitumen may be used. This is equivalent to a range of about 4.5 liters to 27 liters of gas per liter of material comprising bitumen. In certain embodiments, 125 ft³ of gas per ton of material comprising bitumen may be used. In some embodiments, the bitumen-enriched solvent phase may be separated from the first mixture by filtering the first mixture with a plate and frame-type filter press. Any plate and frame-type filter press known to those of ordinary skill in the art may be used. An exemplary plate and frame-type filter press suitable for use in this method is described in U.S. Pat. No. 4,222,873. Generally, the first mixture is pumped into frame chamber located between two filter plates. The first mixture fills the frame chamber and the liquid component of the first mixture migrates out of the frame chamber through the filter cloths of each filter plate, thereby separating the liquid component of the first mixture from the solid component of the first mixture. In this case, the liquid component is the bitumen-enriched solvent phase (i.e., first solvent having bitumen dissolved therein) and the solids component is the first solvent- wet tailings. The bitumen-enriched solvent phase that has passed out of the frame chamber is routed out of the plate and frame-type filter press while the first solvent-wet tailings are left behind in the frame chamber.

When utilizing a plate and frame-type filter press to separate the first mixture, pressurized gas may be injected into the frame chamber after the frame chamber has been filled with the first mixture to promote the separation of the bitumen-enriched solvent phase from mineral solids in the first mixture. The introduction of pressurized gas into the frame chamber may proceed according to the details provided above for applying pressurized gas over a first mixture.

In some embodiments, separating 1100 bitumen-enriched solvent phase from the first mixture may include a second separation stage in addition to the separation described above. When the bitumen-enriched solvent phase is removed from the first mixture, a residual amount of bitumen-enriched solvent phase may remain in the first mixture. Because the first mixture includes a residual amount of bitumen-enriched solvent phase, the first mixture may now be considered first solvent-wet tailings. Accordingly, the second separation stage may be performed to remove the residual bitumen-enriched solvent phase from the first solvent-wet tailings. The second separation stage may be performed by adding a second quantity of first solvent to the first solvent-wet tailings. The addition of a second quantity of first solvent displaces the residual bitumen-enriched solvent phase and thereby forces the residual bitumen- enriched solvent phase out of the first solvent-wet tailings. Some of the second quantity of the first solvent may remain in the first solvent-wet tailings, but little to no bitumen-enriched solvent phase remains. In this manner, the first solvent-wet tailings may remain first solvent-wet tailings even after the second stage of separation, although the first solvent-wet tailing become essentially bitumen-free.

Any suitable amount of first solvent may be added to the first solvent- wet tailings in order to displace the bitumen-enriched solvent phase. In some embodiments, the second quantity of first solvent may be added to the first solvent- wet tailings in an amount of from about 10% to about 200% of the first quantity of first solvent mixed with the material comprising bitumen.

The second quantity of first solvent may also be added to the first solvent-wet tailings in any suitable fashion. For example, where the first solvent-wet tailings remain loaded in the frame chamber of a plate and frame-type filter press as described above, the second quantity of first solvent may be added to the frame chamber to displace the residual bitumen-enriched solvent phase out of the first-solvent wet tailings and through the filter screens on either side of the filter chamber.

The solvent used for the second quantity of first solvent may be the same solvent used for the first quantity of first solvent. Alternatively, the solvent used for the second quantity of first solvent may be a different solvent from the solvent used for the first quantity of first solvent. However, the second quantity of first solvent is still of the type of first solvents described in greater detail above (e.g., a light aromatic solvent).

The residual bitumen-enriched solvent phase displaced from the first solvent-wet tailings may include predominantly bitumen and first solvent. In some embodiments, the residual bitumen-enriched solvent phase may include from about 5 wt% to about 50 wt% bitumen and from about 50 wt% to about 95 wt% first solvent. Little to no non-bitumen components of the material comprising bitumen may be present in the residual bitumen-enriched solvent phase. After removal of the residual bitumen-enriched solvent phase, the first solvent- wet tailings may include little or no bitumen. In some embodiments, the first solvent-wet tailings may include from 0 wt% to about 2 wt% bitumen, from about 2 wt% to about 15 wt% first solvent, and from about 83 wt% to about 98 wt% non-bitumen components.

The residual bitumen-enriched solvent phase collected from the second separation stage may be combined with the bitumen-enriched solvent phase collected from the first separation stage prior to any further processing conducted on the bitumen-enriched solvent phase.

In certain embodiments, the second separation stage may be carried out by washing the first solvent-wet tailings with the second quantity of first solvent in a countercurrent process. The countercurrent process may generally include moving the first solvent-wet tailings in one direction while passing the second quantity of first solvent through the first solvent- wet tailings in an opposite direction. For example, the first solvent-wet tailings may be loaded at the bottom of a screw classifier conveyor positioned at an incline, while second quantity of first solvent may be introduced at the top of the screw classifier conveyor. An exemplary screw classifier conveyor suitable for use in this method is described in U.S. Pat. No. 2,666,242. As the screw classifier conveyor moves the first solvent-wet tailings upwardly, the second quantity of first solvent may flow down the inclined screw classifier conveyor and passes through the first solvent-wet tailings. The second quantity of first solvent may displace any residual bitumen- enriched solvent phase contained in the first solvent-wet tailings, thereby "washing" the bitumen from the first solvent-wet tailings.

Separation of the residual bitumen-enriched solvent phase and the first solvent-wet tailings may naturally occur based on the configuration of the screw classifier conveyor, with the predominantly liquid residual bitumen-enriched solvent phase collecting at one end of the washing unit and the predominantly solid first solvent-wet tailings at the opposite end of the washing unit. For example, when an inclined screw classifier conveyor is used, the residual bitumen-enriched solvent phase may collect at the bottom of the screw classifier conveyor, while the first solvent- wet tailings may collect at the top of the screw classifier conveyor. The residual bitumen-enriched solvent phase may include predominantly bitumen and first solvent. In some embodiments, the residual bitumen-enriched solvent phase may include from about 5 wt% to about 50 wt% bitumen and from about 50 wt% to about 95 wt% first solvent. The bitumen- enriched solvent phase may include relatively minor amounts of non-bitumen components of the material comprising bitumen. The first solvent-wet tailings may include predominantly first solvent and non-bitumen components of the material comprising bitumen. The first solvent component of the first solvent-wet tailings may be first solvent that does not pass all the way through the first solvent-wet tailings in the countercurrent washing process. In some embodiments, the first solvent-wet tailings may include from about 5 wt% to about 20 wt% first solvent and from about 80 wt% to about 95 wt% non-bitumen components (e.g., mineral solids). The first solvent-wet tailings may include no bitumen, especially in the case where additional quantities of first solvent are added to the first solvent- wet tailings as described in greater detail below.

The countercurrent process may include multiple stages. For example, after a first pass of first solvent through the first solvent- wet tailings, the resulting residual bitumen-enriched solvent phase may be passed through the first solvent-wet tailings several more times. Alternatively, additional quantities of fresh first solvent may be passed through the first solvent- wet tailings one or more times. In this manner, the residual bitumen-enriched solvent phase or fresh quantities of first solvent may become progressively more enriched with bitumen after each stage and the first solvent-wet tailings may lose progressively more bitumen after each stage.

The first solvent component of the first solvent- wet tailings may be separated 1200 from the first solvent- wet tailings by adding a second solvent to the first solvent- wet tailings. Addition of the second solvent may displace the first solvent component and force the first solvent out of the first solvent-wet tailings. As noted above, the first solvent-wet tailings may include from about 5 wt% to about 20 wt% of the first solvent, and it is desirable to remove this first solvent from the tailings to make the tailings more environmentally friendly. The second solvent can be any suitable solvent that is useful for displacing the first solvent, and can include any of the second solvents described in greater detail above. Adding second solvent to the first solvent-wet tailings may be carried out in any suitable manner that results in first solvent displacement from the first solvent- wet tailings. In some embodiments, second solvent may be added to the first solvent-wet tailings in a similar or identical manner to the addition of first solvent to the first solvent-wet tailings described in greater detail above. The amount of the second solvent added to the first solvent-wet tailings may be sufficient to effectively displace at least a portion, or desirably all, of the first solvent in the first solvent-wet tailings. The amount of second solvent added to the first solvent-wet tailings may be approximately 0.5 to 1 times the amount of bitumen by volume originally contained in the material comprising bitumen. In some embodiments, the addition of second solvent to the first solvent- wet tailings may result in the removal of 95% or more of the first solvent in the first solvent-wet tailings. The first solvent may leave the first solvent-wet tailings as a first solvent-second solvent mixture. The first solvent-second solvent mixture may include from about 5 wt% to about 50 wt% first solvent and from about 50 wt% to about 95 wt% second solvent. The removal of the first solvent from the first solvent- wet tailings through the addition of second solvent may result in a quantity of second solvent not passing all the way through the first solvent-wet tailings. Accordingly, the first solvent-wet tailings may become a second solvent- wet tailings upon separation of the first solvent. In some embodiments, the second solvent-wet tailings may include from about 70 wt % to about 95 wt% non-bitumen components and from about 5 wt% to about 30 wt% second solvent. As with previously described separation steps, separation of the first solvent from the first solvent-wet tailings by adding second solvent may be preceded or followed by applying pressurized gas over the first solvent-wet tailings. Applying a pressurized gas over the first solvent-wet tailings may facilitate the separation of the first solvent component of the first solvent-wet tailings from the non-bitumen components of the first solvent-wet tailings. The liberated first solvent can then be displaced from the first solvent-wet tailings by applying additional second solvent to the first solvent- wet tailings. The application of a gas overpressure may also displace first solvent from the first solvent-wet tailings by providing a driving force across a filtration element (i.e., the non-bituminous components of the first solvent- wet tailings). Any suitable gas may be used. In some embodiments, the gas is nitrogen, carbon dioxide or steam. The gas may also be added over the second mixture in any suitable amount. In some embodiments, 62.5 ft³ to 375 ft³ of gas per ton of material comprising bitumen may be used. This is equivalent to a range of about 4.5 liters to 27 liters of gas per liter of material comprising bitumen. In certain embodiments, 125 ft³ of gas per ton of material comprising bitumen may be used.

In some embodiments, separating 1200 first solvent component of the first solvent- wet tailings may utilize a plate and frame-type filter press to separate the first solvent from the first solvent- wet tailings. The plate and frame-type filter press may be a separate plate and frame-type filter press from the plate and frame-type filter press used to separate the bitumen- enriched solvent phase from the first mixture and/or the first solvent-wet tailings, or the same plate and frame-type filter press may be used to separate the bitumen-enriched solvent phase from the first mixture (or first solvent-wet tailings) and to separate the first solvent from the first solvent-wet tailings. When the same plate and frame-type filter press is used, the method may include adding second solvent to the first solvent-wet tailings still contained in the frame chamber. In other words, the method need not include a step of removing the first solvent-wet tailings (containing mostly solid phases) from the plate and frame-type filter press before mixing with second solvent. The second solvent may be pumped into the plate and frame-type filter press where it displaces the first solvent component of the first solvent- wet tailings located in the frame chambers as it either filters down from the top to the bottom or is pumped upwards from the bottom to the top. When utilizing a plate and frame-type filter press to separate the first solvent from the first solvent- wet tailings, pressurized gas may be injected into the frame chamber after the frame chamber has been filled with the first solvent-wet tailings. Injecting pressurized gas into the first solvent-wet tailings may promote the separation of the first solvent from mineral solids in the first solvent-wet tailings. The process for adding gas may be similar or identical to the method described above with respect to separation of the bitumen-enriched solvent phase from the first mixture (or first solvent-wet tailings) in a plate and frame-type filter press.

The second solvent may passes through the first solvent-wet tailings loaded in the frame chamber and displaces the first solvent. In some embodiments, 95% or more of the first solvent in the first solvent-wet tailings may be displaced by the second solvent. This first solvent may pass through the filter clothes and out of the frame chamber. Some of the second solvent may also pass through the filter clothes, while some second solvent may remain in the frame chamber. As such, the first solvent-wet tailings may become second solvent-wet tailings.

The separation of first solvent from the first solvent-wet tailings through the addition of second solvent may also be carried out as a countercurrent washing process. The countercurrent process may generally include moving the first solvent-wet tailings in one direction while passing the second solvent through the first solvent-wet tailings in an opposite direction. For example, the first solvent-wet tailings may be loaded at the bottom of a screw classifier conveyor positioned at an incline, while second solvent may be introduced at the top of the inclined screw classifier conveyor. As the screw classifier conveyor moves the first solvent- wet tailings upwardly, the second solvent may flow down the inclined screw classifier conveyor and pass through the first solvent-wet tailings. The two materials may mix and first solvent may be displaced by the second solvent, thereby "washing" the first solvent from the first solvent-wet tailings. In some embodiments, 85% or more of the first solvent in the first solvent-wet tailings may be displaced by the second solvent. The first solvent-second solvent mixture that collects at one end of the screw classifier conveyor may include from about 5 wt% to about 50 wt% first solvent and from about 50 wt% to about 95 wt% second solvent. Some of the second solvent may remain with the tailings, thereby forming the second solvent-wet tailings that collect at the opposite end of the screw classifier conveyor. In some embodiments, the second solvent-wet tailings may include from about 10 wt% to about 30 wt% second solvent and from about 70 wt% to about 90 wt% non-bitumen components. The countercurrent process may include multiple stages as described in greater detail above with respect to washing the first mixture or first solvent- wet tailings. In a multiple stage countercurrent process, the second solvent may displace progressively more first solvent after each stage and the first solvent-wet tailings lose progressively more first solvent after each stage. The second solvent may be removed from the second solvent- wet tailings at 130 to thereby produce solvent-dry, stackable tailings. Any manner of removing second solvent from the second solvent-wet tailings may be used. In some embodiments, the second solvent may be removed from the second solvent- wet tailings by drying, flashing or heating the second solvent- wet tailings. In certain embodiments, second solvent may be separated and recovered at an elevated temperature or reduced pressure to above or below atmospheric pressure to recover the secondary solvent depending on the solvent flash point. For example, the process may include flashing off a gaseous second solvent under controlled pressure let down or vacuum recovery of a less volatile secondary solvent without the need for elevated temperature.

Once the second solvent is separated from the second solvent-wet tailings, solvent- dry, stackable tailings may be left behind. Separation of the second solvent from the second solvent-wet tailings may result in 95% or more of the second solvent in the second solvent-wet tailings being removed.

When the second solvent is a volatile hydrocarbon, the energy required to remove the second solvent may be minimal. In some embodiments, the second solvent may be removed from the second solvent-wet tailings at room temperature. The second solvent removed from the second solvent-wet tailings as a vapor may be recompressed or condensed and recycled back in the process.

Removing 1300 second solvent from the second solvent- wet tailings may also include separation of any residual amount of first solvent that has remained in the second solvent-wet tailings despite separation 1200. Separation of the first solvent may occur together with the separation of the second solvent, such as by heating or flashing the second-solvent wet tailings in a manner causing both solvents to evaporate from the second-solvent wet tailings. Alternatively, the separation may be incremental, wherein the flashing or heating is carried out to start with at conditions that will cause only the second solvent to evaporate, followed by adjusting the conditions to cause the evaporation of the first solvents. Any solvent removed from the second solvent- wet tailings may be recovered for further use, such as by sending the evaporated solvents to stills.

The solvent-dry, stackable tailings resulting from removal of the second solvent from the second solvent-wet tailings may generally include inorganic solids, such as sand and clay, water, and little to no first and second solvent. As used herein, the term "solvent-dry" means containing less than 0.1 wt% total solvent. As used herein, the term "stackable" means having a water content of from about 2 wt% to about 15 wt%. This range of water content may create a damp tailings that will not produce dust when transporting or depositing the tailings. This range of water content may also provide a stackable tailings that will not flow like dry sand, and therefore has the ability to be retained within an area without the need for retaining structures (e.g., a tailings pond). This range of water content may also provide tailings that are not so wet as to be sludge-like or liquid-like. The solvent-dry, stackable tailings produced by the above described method may also include less than 2 wt% bitumen and asphaltene.

With reference to FIG. 8, a system 2000 for carrying out the above-described method, may include a mixer 2050 for mixing material comprising bitumen 2100 and first solvent 2150. Any suitable mixing vessel may be used, including a mixing vessel that operates under pressure in order to maintain the first solvent as a liquid. A first mixture 2200 is formed by the mixing of the material comprising bitumen 2100 and the first solvent 2150 in the mixer 2050. The first mixture 2200 is transported to a first separation unit 2250 where a bitumen-enriched solvent phase 2300 is separated from the first mixture 2200. Any separation unit suitable for separating the bitumen-enriched solvent phase 2300 from the first mixture 2200. In some embodiments, first separation unit 2250 is a plate and frame filter press. Gas 2850-1 may be pumped into the first separation unit 2250 to promote separation of bitumen from the non-bitumen components of the material comprising bitumen. When gas 2850-1 is pumped into first separation unit 2250, the spent gas may also exit the first separation unit 2250 with the bitumen-enriched solvent phase 2300. Because the gas does not dissolve in either the bitumen or the first solvent of the first mixture 2200, the gas exits with the bitumen-enriched solvent phase and does not require any additional separation processing. Removal of the bitumen-enriched solvent phase 2300 from the first mixture 2200 via first separation unit 2250 results in the first mixture 2200 becoming first solvent-wet tailings 2350. The first solvent-wet tailings 2350 produced by the first separation unit 2250 are transported to a second separation unit 2400 where second solvent 2450 is added to the first solvent-wet tailings 2350 in order to separate first solvent 2550 from the first solvent- wet tailings 2350. Any separation unit suitable for separating the first solvent 2550 from the first solvent wet tailings 2350 may be used. In some embodiments, second separation unit 2400 is a plate and frame filter press. Gas 2850-2 may be pumped into the second separation unit 2400 to promote separation of the first solvent 2550 from the non-bitumen components of the first solvent-wet tailings 2350. When gas 2850-2 is pumped into second separation unit 2400, the spent gas may also exit the second separation unit 2400 with the first solvent 2550. Because the gas does not dissolve in the first solvent 2550, the gas exits without need for any additional separation processing.. Separation of the first solvent 2550 from the first solvent-wet tailings 2350 results in the first solvent-wet tailings 2350 becoming second solvent-wet tailings 2500. The second solvent- wet tailings 2500 are transported to a third separation unit 2600 where the second solvent is removed from the second solvent-wet tailings 2500 phase to thereby form solvent-dry, stackable tailings 2700. hi this regard, the third separation unit 2600 produces solvent-dry, stackable tailings 2700 and a removed second solvent stream 2650. The third separation unit 2600 may be any suitable unit capable of removing second solvent 2650 from the second solvent- wet tailings 2500. For example, the third separation unit 2600 may be a dryer, a heater or a flashing unit to evaporate the second solvent from the second solvent-wet tailings 250.0

With reference to FIG. 9, a variation of the system used to carry out the method of the above embodiment includes the use of countercurrent. Pre-mixture 3100 includes material comprising bitumen mixed with first solvent to cause bitumen to dissolve in the first solvent.

Washing unit 3050 receives the pre-mixture 3100 moving in a first direction and first solvent 3150 moving in an opposite direction. The material comprising bitumen 3100 mixes with the first solvent 3150, during which the dissolved bitumen in the pre-mixture 3100 is displaced from the pre-mixture 3100 by the first solvent 3150. As such, a bitumen-enriched solvent phase 3200 and a first solvent-wet tailings 3250 are formed. The bitumen-enriched solvent phase 3200 and the first solvent- wet tailings 3250 separate due to the countercurrent configuration of the washing unit 3050. First solvent-wet tailings 3250 are transported to a second washing unit 3300 where it flows in a direction opposite to a direction of flow of second solvent 3350 introduced into the second washing unit 3300. The first solvent-wet tailings 3250 mix with the second solvent 3350, during which the first solvent in the first solvent-wet tailings 3250 is displaced by the second solvent 3350. As such, first solvent-second solvent mixture 3400 and second solvent- wet tailings 3450 are formed. The first solvent-second solvent mixture 3400 and the second solvent- wet tailings 3450 separate due to the countercurrent configuration of the second washing unit 3300. Second solvent-wet tailings 3450 are transported to first separation unit 3500 where second solvent 3550 is removed from the second solvent-wet tailings 3450 to produce solvent- dry, stackable tailings 3600. First separation unit 3500 may be any suitable separation unit for removing second solvent 3550, such as a heating unit or a flashing unit.

In certain embodiments, a method for producing solvent-dry, stackable tailings may include loading a mixture of material comprising bitumen and first solvent in a vertical column and treating the mixture by injecting solvents at the top of the vertical column. Additional first solvent may be injected at the top of the vertical column to extract bitumen from the material comprising bitumen as the first solvent travels through the material comprising bitumen. Second solvent may also be injected at the top of the vertical column to remove first solvent from the material loaded in the vertical column. Such treatment results in production of solvent-dry, stackable tailings in the vertical column.

With reference to FIG. 10 the method according to this embodiment may include forming 4000 a first mixture by mixing material comprising bitumen with a first quantity of first solvent. Forming 4000 first mixture may be similar or identical to the mixing process 1000 described in greater detail above. Any mixing processes may be used to mix the material comprising bitumen with the first quantity of first solvent. The material comprising bitumen may be mixed with the first solvent in the same ratios as set forth above. In some embodiments, the aim of mixing at 4000 is to create a first mixture that has a suitable viscosity for pumping the first mixture. If too much first solvent is added to the material comprising bitumen, then it may not be possible to pump the first mixture because all of the non-bitumen components of the first mixture will settle out. If too little first solvent is added to the material comprising bitumen, then it may not be possible to pump the first mixture because it is too viscous. Accordingly, the amount of first solvent added to the material comprising bitumen when forming the first mixture may be an amount that results in the first mixture having a viscosity in the range of from 2 to 50 centipoise.

In certain embodiments, the amount of first solvent added when forming 4000 the mixture is from about 0.5 to about 1.25, and preferably 0.75 times the amount of bitumen by volume in the original material comprising bitumen. As with mixing 1000, the material comprising bitumen used in when forming 4000 the mixture may be any material having 3 wt% or more bitumen content and the first solvent may generally be a light aromatic solvent capable of dissolving the bitumen in the material comprising bitumen. By mixing the first quantity of first solvent with the material comprising bitumen, the first quantity of first solvent may begin to dissolve the bitumen in the material comprising bitumen. As such, the first mixture may begins to form two phases. The first phase may be the bitumen-enriched solvent phase and the second phase may be the first solvent-wet tailings. 50% or more of the bitumen in the material comprising bitumen may be dissolved upon the addition of the first quantity of first solvent to the material comprising bitumen. The first mixture may be loaded 4100 in a vertical column. Any method of loading the first mixture in the vertical column may be used. First mixture may be poured into the vertical column or, when an appropriate first mixture viscosity is obtained from mixing 4000, the first mixture may be pumped into the vertical column. First mixture may generally be loaded in the vertical column by introducing the first mixture into the column at the top end of the vertical column. The bottom end of the vertical column may be blocked, such as by a removable plug or by virtue of the bottom end of the vertical column resting against the floor. In some embodiments, a metal filter screen at the bottom end of the vertical column may be used to maintain the first mixture in the vertical column. Accordingly, introducing first mixture at the top end of the vertical column may fill the vertical column with first mixture. The amount of first mixture loaded in the vertical column may be such that the first mixture substantially fills the vertical column with first mixture. In some embodiments, first mixture may be added to the vertical column to occupy 90% or more of the volume of the vertical column. In some embodiments, the first mixture may not be filled to the top of the vertical column so that room is provided to inject first solvent, second solvent, etc., into the vertical column.

As noted above, the column may have a generally vertical orientation. The vertical orientation may include aligning the column substantially perpendicular to the ground, but also may include orientations where the column forms angles less than 90° with the ground. The column may generally be oriented at any angle that results in gravity aiding the flow of the first solvent, second solvent, etc., from one end of the column to the other. In some embodiments, the column may be oriented at an angle anywhere within the range of from about 1° to 90° with the ground. In a preferred embodiment, the column may be oriented at an angle anywhere within the range of from about 15° to 90° with the ground.

The material of the vertical column is also not limited. Any material that will hold the first mixture within the vertical column may be used. The material may also preferably be a non-porous material such that various liquids injected into the vertical column may only exit the column from one of the ends of the vertical column. The material may be a corrosive resistant material so as to withstand the potentially corrosive components of the first mixture loaded in the column as well as any potentially corrosive materials injected into the vertical column.

The shape of the vertical column is not limited to a specific configuration. Generally speaking, the vertical column may have two ends opposite one another, designated a top end and a bottom end. The cross-section of the vertical column may be any shape, such as a circle, oval, square or the like. The cross-section of the vertical column may change along the height of the column, including both the shape and size of the vertical column cross-section. The vertical column may be a straight line vertical column having no bends or curves along the height of the vertical column. Alternatively, the vertical column may include one or more bends or curves.

Any dimensions may be used for the vertical column, including the height, inner cross sectional diameter and outer cross sectional diameter of the vertical column. In some embodiments, the ratio of height to inner cross sectional diameter may range from 0.5 : 1 to 15 : 1.

Once first mixture is loaded in the vertical column, a second quantity of first solvent may be injected 4200 into the vertical column. The second quantity of first solvent may be injected into the vertical column at the top end of the column such that the second quantity of first solvent flows down and through the first mixture loaded in the column. The second quantity of first solvent may be injected into the vertical column by any suitable method. In some embodiments, the second quantity of first solvent may be poured into the vertical column at the top end and allowed to flow down through the first mixture loaded therein under the influence of gravity. The amount of first solvent added 4200 to the first mixture is not limited. The amount may preferably be enough first solvent to displace most or all of the dissolved bitumen content of the first mixture. In some embodiments, the amount of first solvent added at 4200 may be from about 1.25 to about 2.25 times the amount of bitumen by volume in the original material comprising bitumen. In some embodiments, the addition 4200 of second quantity of first solvent may be carried out under flooded conditions. In other words, more first solvent may be added to the top of the vertical column than what flows down through the first mixture, thereby creating a head of solvent at the top of the vertical column. Upon injection into the first mixture, the first solvent may flow downwardly through the height of the column via small void spaces in the first mixture. The first solvent may flow downwardly through the force of gravity or by an external force applied to the vertical column. Examples of external forces applied include the application of pressure from the top of the vertical column or the application of suction at the bottom of the vertical column. The first solvent may travel the flow of least resistance through the first mixture. As the first solvent flows downwardly through the first mixture, bitumen contained in the first mixture may be dissolved in the first solvent. In this manner, the first solvent flowing through the first mixture may become bitumen enriched. The first solvent injected into the first mixture may also join together with the first solvent component of the first mixture. Bitumen may already be dissolved in the first solvent component of the first mixture, and thus when the second quantity of injected first solvent joins with the first solvent component of the first mixture, the combined first solvents are bitumen enriched.

The bitumen-enriched solvent that has flowed downwardly through the height of the vertical column may exit the vertical column, where it may be collected 4300 for further use and processing. In some embodiments, the bitumen-enriched solvent may include from about 10 wt% to about 60 wt% bitumen and from about 40 wt% to about 90 wt% first solvent. Minor amounts of non-bitumen material may also be included in the bitumen-enriched solvent phase. In some embodiments, 95 % or more of the bitumen may be removed from the first mixture upon completion of collecting 4300 bitumen-enriched solvent.

Any method of collecting the bitumen-enriched solvent may be used, such as by providing a collection vessel at the bottom end of the vertical column. The bottom end of the vertical column may include a metal filter screen having a mesh size that does not permit first mixture to pass through but which does allow for bitumen-enriched solvent to pass through and collect in a collection vessel located under the screen. Collection of bitumen-enriched solvent may be carried out for any suitable period of time. In some embodiments, collection is carried out for 2 to 30 minutes.

Steps 4200 and 4300 may be repeated several times. In other words, after injecting a second quantity of first solvent and collecting the bitumen-enriched solvent at the bottom of the vertical column, a third quantity of first solvent may be added to the vertical column to extract additional bitumen from the first mixture. Repeating steps 4200 and 4300 may increase the overall extraction rate of bitumen from the first mixture. In some embodiments, the use of multiple first solvent injection steps may result in removing 99% or more of the bitumen in the first mixture.

After collection of bitumen-enriched solvent has been completed or while bitumen- enriched solvent is still being collected, a first quantity of second solvent may be injected 4400 into the column. Second solvent may be similar or identical to the second solvent described in greater detail in the previous embodiment. In some embodiments, the second solvent may be a volatile hydrocarbon solvent.

The first quantity of second solvent may be injected into the column at the top end of the column such that the first quantity of second solvent flows down and through the first mixture loaded in the column. The first quantity of second solvent may be injected into the vertical column by any suitable method. In some embodiments, the first quantity of second solvent may be poured into the vertical column at the top end and allowed to flow down through the first mixture loaded therein.

The amount of second solvent added 4400 to the first mixture is not limited. The amount may preferably be enough second solvent to displace most or all of the first solvent contained in the first mixture. In some embodiments, the first quantity of second solvent added to the first mixture may be from about 0.5 to about 2.0, and preferably about 1 times the amount of bitumen by volume contained in the original material comprising bitumen. If multiple second solvent addition steps are performed, then the total amount of second solvent added may be about 1.0 times the amount of bitumen by volume contained in the original material comprising bitumen.

Upon injection into the first mixture, the second solvent may flow downwardly through the height of the column via void spaces in the first mixture. The second solvent may flow down the height of the vertical column under the force of gravity or by an external force applied to the vertical column, such as pressure at the top end of the vertical column or suction at the bottom end of the vertical column. The second solvent may travel the flow of least resistance through the first mixture. As the second solvent flows downwardly through the first mixture, first solvent in the first mixture may be dissolved in the second solvent. In this manner, the second solvent may become first solvent-enriched.

The first solvent-enriched second solvent that has flowed downwardly through the height of the column may exit the column where it may be collected 4500 for further use and processing. In some embodiments, the first solvent-enriched second solvent may include from about 50 wt% to about 90 wt% second solvent and from about 10 wt% to about 50 wt% first solvent. Minor amounts of bitumen and non-bitumen material may also be included in the first solvent-enriched second solvent phase. In some embodiments, 95% of the first solvent may be removed from the first mixture upon completion of collecting 4500 the first solvent-enriched second solvent.

In some embodiments, the addition 4400 of second solvent may be carried out under flooded conditions. In other words, more second solvent may be added to the top of the vertical column than what flows down through the first mixture, thereby creating a head of solvent at the top of the vertical column.

Any method of collecting 4500 the first solvent-enriched second solvent may be used, such as by providing a collection vessel at the bottom end of the vertical column. The bottom end of the vertical column may include a metal filter screen having a mesh size that does not permit first mixture to pass through but which does allow for first solvent-enriched second solvent to pass through and collect in a collection vessel located under the screen. Collection of first solvent-enriched second solvent may be carried out for any suitable period of time. In some embodiments, collection may be carried out for 2 to 30 minutes.

Steps 4400 and 4500 may be repeated one or more times. In other words, after injecting a first quantity of second solvent and collecting the first solvent-enriched second solvent at the bottom of the vertical column, a second quantity of second solvent may be added to the vertical column to extract additional first solvent from the first mixture. Repeating steps 4400 and 4500 may increase the overall removal rate of first solvent from the first mixture. In some embodiments, the use of multiple second solvent injection steps may result in removing 99% or more of the first solvent in the first mixture. The first mixture is discharged 4600 from the column. The first mixture may be removed from the vertical column by any suitable process. The first mixture loaded in the vertical column may be removed from either the top end or the bottom end of the vertical column. In some embodiments, the bottom end of the vertical column may be covered with a removable plug, and the plug may be removed to allow the first mixture loaded in the vertical column to discharge out of the vertical column by the force of gravity. For example, if the bottom end of the vertical column is blocked by a screen as described in greater detail above, the screen may be removed to allow the first mixture loaded in the vertical column to flow out of the vertical column. In certain embodiments, the vertical column may be lifted off of the ground, thereby allowing the first mixture loaded in the vertical column to flow out of the bottom end of the vertical column. External forces may also be applied to the vertical column to promote the discharging of the first mixture from the vertical column. The discharged first mixture may generally include non-bitumen components of the material comprising bitumen (e.g., mineral solids) and a relatively small amount of second solvent. In some embodiments, the discharged first mixture may be from about 80 wt% to about

95 wt% non-bitumen components and from about 5 wt% to about 20 wt% second solvent. The discharged first mixture may include little or no first solvent and little or no bitumen.

The residual second solvent in the discharged first mixture may be removed 4700 from the discharged first mixture to produce solvent-dry, stackable tailings. Any suitable procedure may be used to remove the residual second solvent from the discharged first mixture. In some embodiments, the discharged first mixture may be flashed or dried in order to remove the second solvent. The removal of second solvent may include recovering the second solvent for reuse in the above method. Such recovery may include condensing the evaporated second solvent back into a liquid form.

In one variation to discharging, the removal of the residual second solvent may be performed prior to discharging the first mixture from the vertical column. Such removal may be carried out by any suitable process for removing second solvent from first mixture loaded in the vertical column. In some embodiments, heated gas may be injected into the first mixture in order to remove the residual second solvent. Heated gas may be injected into the first mixture by any suitable process. In some embodiments, the gas may be added to a freeboard on top of the first mixture loaded in the column. In certain embodiments, one or more gas injection lines may run down through the first mixture loaded in the vertical column. These lines may be placed down the center of the vertical column, along the sides of the vertical column, or a combination of both. In certain embodiments, a double walled vertical column may be provided, with the internal wall being porous. Gas may be pumped into the space between the two walls. The gas may then travel into the first mixture loaded in the inner most cylinder of the vertical column by traveling through the porous inner wall. Any suitable gas may be used for this removal step, such as nitrogen, carbon dioxide or steam. The gas may generally be heated to a temperature above the boiling point temperature of the second solvent in order to result in the removal of the second solvent from the first mixture. The amount of gas added to the first mixture is not limited. In some embodiments, 3.5 m³ of heated gas may be added per 20 kg of first mixture. The gas injected into the first mixture loaded in the vertical column and the evaporated second solvent may exit the vertical column at the bottom end of the vertical column. For example, where the bottom end of the vertical column includes a metal filter screen, the gases may pass through the filter screen. Gas exiting the vertical column may be collected and reused within the process.

Once the second solvent is removed, a solvent-dry, stackable tailings may be produced. The majority of the bitumen in the first mixture may be removed via the first solvent, the majority of the first solvent in the first mixture may be removed via the second solvent, and the majority of the second solvent in the first mixture may be removed via a process such as flashing or drying, thereby resulting in the formation of solvent-dry, stackable tailings. The solvent-dry, stackable tailings may generally include inorganic solids, such as sand and clay, water content, and little or no solvent. In some embodiments, the solvent-dry, stackable tailings may be considered solvent-dry because they include less than 0.1 wt% total solvent. Similarly, the solvent-dry, stackable tailings may be considered stackable because they include a water content in the range of from 2 wt% to 15 wt%. This range of water content may reduce or eliminate the problem of tailings dust during transportation and deposition of the tailings. Further, this range or water content may provide for solvent-dry, stackable tailings that may be deposited without requiring retention infrastructure to maintain the tailings in place. The solvent-dry, stackable tailings may include less than 2 wt% bitumen and asphaltene.

Additional steps may be included in the method of this embodiment to farther accomplish the production of solvent-dry, stackable tailings. In one example, the method may further include one or more gas purge steps. Gas purge steps may be performed before or after any of the solvent injection steps. The gas purge steps may help to separate dissolved bitumen and/or first solvent from the non-bitumen components of first mixture. Once dissolved bitumen is separated from non-bitumen components via the gas purge, the dissolved bitumen may be more readily displaced by the first solvent. Similarly, once first solvent is separated from non- bitumen components via the gas purge, the first solvent may be more readily displaced by the second solvent.

The gas may be injected into the vertical column in any suitable manner. In some embodiments, the gas may be added to a freeboard on top of the first mixture loaded in the column. In certain embodiments, one or more gas injection lines may run down through the first mixture loaded in the vertical column. These lines may be placed down the center of the vertical column, along the sides of the vertical column, or a combination of both. In certain embodiments, a double walled vertical column may be provided, with the internal wall being porous. Gas may be pumped into the space between the two walls. The gas may then travel into the first mixture loaded in the inner most cylinder of the vertical column by traveling through the porous inner wall.

Any amount of gas may be injected into the first mixture to remove dissolved bitumen. In some embodiments, between 50 and 200 ft³ of gas per ton of material comprising bitumen feed may be used. The gas used in the gas purges is not limited. In some embodiments, the gas may be an inert gas. For example, the gas may be nitrogen, carbon dioxide, or steam.

Another step may include injecting cooled gas into the vertical column to purge the vertical column. Cooled gas may be added to remove the gaseous second solvent present in interstitial spaces of the tailings after a heated gas has been injected to vaporize second solvent. Any suitable gas may be used. In some embodiments, the gas is nitrogen or carbon dioxide.

With reference to FIG. 11, a system that may be used to carry out the method of this embodiment may include a mixing vessel 5050 for mixing material comprising bitumen 5100 with a first quantity of first solvent 5150 to form a first mixture 5200. Any type of mixing vessel may be used to mix the material comprising bitumen 5100 and the first solvent 5150.

The first mixture 5200 is then loaded in the vertical column 5250. FIG. 11 depicts the first mixture 5200 being loaded in the top end of the vertical column 5250, but the first mixture

5200 can also be loaded from the bottom end of the vertical column 5250 or from the side of the vertical column 5250. Once the first mixture 5200 is loaded in the vertical column 5250, a second quantity of first solvent 5300 is injected into the top end of the vertical column. The second quantity of first solvent 5300 flows down the height of the vertical column 5250, dissolving solid bitumen in the first mixture 5200 and/or displacing dissolved bitumen in the first mixture 5200 along the way. The non-bitumen components of the material comprising bitumen remain in a packed condition in the vertical column 5250 as the second quantity of first solvent 5300 passes through the first mixture 5200. The second quantity of first solvent 5300 exits the bottom end of the vertical column 5250 as a bitumen-enriched solvent phase 5350. The second quantity of first solvent 5300 is now a bitumen-enriched solvent phase 5350 because the second quantity of first solvent 5300 dissolves solid bitumen contained in the first mixture 5200 and/or coalesces with dissolved bitumen contained in the first mixture 5200 as the second quantity of first solvent 5300 passed through the vertical column 5250.

The bitumen-enriched solvent phase 5350 is collected at the bottom end of the vertical column 5250 for further processing of the bitumen contained therein. Some of the second quantity of first solvent 5300 remains in the first mixture 5200 loaded in the vertical column 5250. A first quantity of second solvent 5400 is then added to the vertical column 5250. The first quantity of second solvent 5400 flows down the height of the vertical column 5250, dissolving and/or displacing first solvent contained in the first mixture 5200. The first quantity of second solvent 5400 exits the bottom end of the vertical column 5250 as a first solvent- enriched second solvent phase 5450.

The first solvent-enriched second solvent phase 5450 is collected at the bottom end of the vertical column 5250 to recover and possibly reuse the first and second solvents contained therein. Optionally, the system also includes a series of gas purge injections 5550-1, 5550-2, and 5550-3. The gas purge injections 5550-1, 5550-2, and 5550-3 may occur before and/or after any of the solvent injection steps, and may serve to help separate bitumen and first solvent from the non-bitumen component of the first mixture 5200. While not depicted in FIG. 11, still other gas streams may be injected into the vertical column 5250. For example, a hot gas stream may be injected into the vertical column after the first quantity of second solvent 5400 has been added to the first mixture 5200 in order to vaporize any second solvent that does not exit the vertical column 5250 at the bottom end of the vertical column 5250.

Once all of the solvent and gas streams have been injected, the first mixture 5200 becomes solvent-dry, stackable tailings 5500 which are discharged out of the vertical column 5250. FIG. 11 depicts solvent-dry, stackable tailings 5500 being removed from the bottom end of the vertical column 5250, but the solvent-dry, stackable tailings 5500 may also be discharged from the top end of the vertical column 5250.

FIG. 12 is a photograph of solvent-dry, stackable tailings derived from processing about 600 kg of Athabasca oil sands containing about 12.5 wt% bitumen in a system as illustrated in FIG. 11. The solvent-dry, stackable tailings shown contain less than 0.1 wt% bitumen.

In both embodiments described above, the method can include a further step of depositing the solvent-dry, stackable tailings in a mine pit formed when mining the first material comprising bitumen. The manner in which the solvent-dry, stackable tailings are deposited in the mine pit is not limited. In one example, the solvent-dry, stackable tailings may be transported to the mine pit by one or more trucks and poured into the mine pit from the trucks. Solvent-dry, stackable tailings may also be deposited in a mine pit through the use of conveyor belts that empty into the mine pits. In some embodiments, the volume of solvent-dry, stackable tailings produced from the mined material comprising bitumen may be less than the original amount of material comprising bitumen mined such that the entirety of the solvent-dry, stackable tailings may be deposited in the mine pit. To the contrary, conventional hot water processing of material comprising bitumen may generally produce wet tailings having a volume that is 125% of the original volume of the mined material comprising bitumen, even after settling and decanting of excess liquid. Additionally, the presence of some amount of water in the solvent- dry, stackable tailings may aid in the compaction of the solvent-dry, stackable tailings. This may lead to a much earlier trafficable reclamation for the deposit, an aspect of tailings management which has not been attained by tar sands operators to date.

As described in greater detail in co-pending U.S. Application Nos. 12/041,554 and 11/249,234, further processing may be performed on other components produced by the methods described above. For example, the bitumen-enriched solvent phase may be processed to separate the bitumen therefrom. Furthermore, as described in co-pending application No. 12/509,298, herein incorporated by reference, any bitumen obtained from the above-described methods or from further processing of the bitumen-enriched solvent phases produced by the above-described processes may be cracked in a nozzle reactor (with or without deasphalting) to produce light hydrocarbon distillate. The light hydrocarbon distillate may then be used as a first solvent to extract bitumen from material comprising bitumen. In one example, the light hydrocarbon distillate produced may be recycled within the same process to initiate extraction of bitumen from further material comprising bitumen. Additionally, any solvent separated or removed from a mixture may be recovered and reused in the process. For example, the first solvent-enriched second solvent phase may be recovered after being separated from the second solvent-wet tailings and reused in the process. More specifically, the first solvent-enriched second solvent phase is separated into first and second solvent that may be used in the process. Separation of the solvents may be accomplished by any know method, such as through the use of stills.

Any bitumen recovered from the above-described methods, such as the bitumen content of the bitumen-enriched solvent phases, may also undergo any type of upgrading processing known to those of ordinary skill in the art. Upgrading of the bitumen may comprise any processing that generally produces a stable liquid (i. e. , synthetic crude oil) and any subsequent refinement of synthetic crude oil into petroleum products. The process of upgrading bitumen to synthetic crude oil may include any processes known to those of ordinary skill in the art, such as heating or cracking the bitumen to produce synthetic crude. The process of refining synthetic crude may also include any processes known to those of ordinary skill in the art, such as distillation, hydrocracking, hydrotreating and coking. They petroleum products produced by the upgrading process are not limited, any may include petroleum, diesel fuel, asphalt base, heating oil, kerosene, and liquefied petroleum gas.

Examples

Example 1. Semi-Continuous Countercurrent Washing Using a Plate and Frame Horizontal Filter Press

A first bitumen extraction experiment was conducted using a plate and frame filter press. 600 kg of oil sand ore having a bitumen content of 6 wt% (i.e., 36 kg bitumen content) was mixed with a primary solvent of Solvesso 150. The primary solvent to bitumen volume ratio was about 2:1. The primary solvent and oil sand ore was mixed for 15 minutes in a disaggregation device.

The ore/solvent mixture was removed from the disaggregation device and pumped to the plate and frame filter press. The plate and frame filter press was filled through a fill orifice until pressure reached a maximum. The plate and frame filter was pressurized with an inert gas and the bitumen-enriched solvent phase collected at the outlet of the plate and frame filter press. The bitumen-enriched solvent phase weighed 70 kg, including 22 kg of bitumen and 48 kg of primary solvent. First mixture remained in the filter press.

A secondary solvent of methanol was pumped into the plate and frame filter press at a solvent to original bitumen weight volume ratio of 1.5:1. The plate and frame filter press was pressurized with inert atmosphere and the secondary solvent was forced through the first mixture in a plug flow 'washing' action. The secondary bitumen-enriched solvent phase was collected at the outlet of the plate and frame filter press. The secondary bitumen-enriched solvent phase weighed 74 kg, including 7 kg of bitumen and a combined 67 kg of primary and secondary solvent. As 22 kg of bitumen was collected in the primary bitumen-enriched solvent phase and 7 kg of bitumen was collected in the secondary bitumen-enriched solvent phase, a total of 29 kg of bitumen was extracted from 600 kg of oil sand ore having 36 kg of bitumen contained therein. Accordingly, 81% of the bitumen in the sample was extracted from the low grade oil sand.

Example 2. Semi-Continuous Countercurrent Washing Using a Vertical Column

A second bitumen extraction experiment was conducted using a vertical column. 600 kg of oil sand ore having a bitumen content of 6 wt% (i.e., 36 kg bitumen content) was mixed with a primary solvent of Solvesso 150. The primary solvent to bitumen volume ratio was about 2:1. The primary solvent and oil sand ore was mixed for 15 minutes in a disaggregation device.

The ore/solvent mixture was removed from the disaggregation device and pumped to the top end of the vertical column. The vertical column was filled with the ore/solvent mixture until a bed of full height was formed, and the top end of the vertical column was then sealed. The vertical column had a height of 6 feet and an inner diameter of 22 inches. Filtering with the aid of overpressure was then performed to separate a primary bitumen-enriched solvent phase. The vertical column was pressurized with an inert gas and the primary bitumen-enriched solvent phase was collected at the bottom end of the vertical column. The primary bitumen-enriched solvent phase weighed 72 kg, including 24 kg of bitumen and 48 kg of primary solvent. First mixture remained in the vertical column.

A secondary solvent of methanol was pumped into the top end of the vertical column at a solvent to original bitumen volume ratio of 2:1. The vertical column was pressurized with inert atmosphere and the secondary solvent was forced through the first mixture in a plug flow 'washing' action. The secondary bitumen-enriched solvent phase was collected at the bottom end of the vertical column. The secondary bitumen-enriched solvent phase weighed 92 kg, including 8 kg of bitumen and a combined 84 kg of primary and secondary solvent.

As 24 kg of bitumen was collected in the primary bitumen-enriched solvent phase and 8 kg of bitumen was collected in the secondary bitumen-enriched solvent phase, a total of 32 kg of bitumen was extracted from 600 kg of oil sand ore having 36 kg of bitumen contained therein. Accordingly, 89% of the bitumen in the sample was extracted from the low grade oil sand. Example 3. Laboratory Scale Testing Of Low Grade Ore Using Light Aromatic Primary Solvent And Aliphatic Secondary Solvent

One kilogram of low grade oil sand ore, containing about 9% bitumen, was mixed with 400 grams of naphtha (light aromatic primary solvent) in a beaker equipped with an agitator with a bow-tie blade. The mixture of low grade oil sand ore and naphtha was agitated about one hour. The resulting slurry was transferred into a Buchner filter lined with a coarse filter paper. Vacuum was applied for about 15 minutes until the cake appeared to be "dry". The cake removed from the Buchner filter had an API gravity of about 27. The cake was then placed into a 2 liter nutsche with a pressure rating of 20 bar. A 3 bar pressure nitrogen purge was applied to expel a quantity of bitumen-enriched naphtha. Subsequently, about one liter of liquid propane (aliphatic secondary solvent) at 15 bar pressure was added to the nutsche. After the liquid propane at 15 bar pressure was added to the nutsche, the pressure let down valve was opened and the nutsche free board over pressure discharged all of the entrained bitumen-enriched solvent displaced from the cake by the liquid propane. To prevent freezing at the discharge valve, the discharge valve was placed in a temperature controlled hot water bath. Any excess propane that flashed off was burned and vented to the atmosphere. This displacement procedure generally lasted about 15 minutes. After all the propane was removed, another nitrogen purge was performed. A clean and somewhat compacted filter cake was then discharged. The filter cake was analyzed for residual bitumen and assayed 1.23% bitumen. Based on the bitumen content of the original low grade oil sand ore, a bitumen recovery of about 88% was calculated. Example 4. Example 3 for Various Grades of Oil Sands

The bitumen extraction process as described above in Example 3 was performed on oil sand ores of various grades ranging from about 8% to about 13%. The diamond shaped data points in Figure 6 show the bitumen recovery rates for the various grades of oil sands when utilizing the process described in Example 3, while the circle shaped data points show the extraction rates achieved by a conventional hot water process combined with paraffinic froth treatment. Figure 6 also includes a least square fit line for all of the diamond-shaped data points. When comparing the data in FIG. 6 with line A in Figure 1, it can be seen that the method described in Example 3 achieves extraction rates above the rates stipulated by the Alberta Energy and Utilities Board as well as above the results achieved by the convention hot water extraction process. Example 5. Semi-Continuous Countercurrent Washing Using a Plate and Frame Horizontal Filter Press

A first bitumen extraction experiment was conducted using a plate and frame filter press. 200.0 kg of oil sand ore having a bitumen content of 12 wt% was mixed with a primary solvent of Solvesso 150. The primary solvent to bitumen ratio was about 1:1. The primary solvent and oil sand ore was mixed for 15 minutes in a disaggregation device.

The ore/solvent mixture was removed from the disaggregation device and pumped to the plate and frame filter press. The plate and frame filter press was filled through a fill orifice until pressure reached a maximum. The plate and frame filter was pressurized with an inert gas and the bitumen-enriched solvent phase collected at the outlet of the plate and frame filter press. The bitumen-enriched solvent phase weighed 29.0 kg, includingH.O kg of bitumen and 15.0 kg of primary solvent. First solvent- wet tailings remained in the filter press.

A fresh solution of primary solvent was pumped into the plate and frame filter press at a solvent to original bitumen weight ratio of 0.75:1. The plate and frame filter press was pressurized with inert atmosphere and the fresh primary solvent was forced through the first solvent-wet tailings in a plug flow 'washing' action. The secondary bitumen-enriched solvent phase was collected at the outlet of the plate and frame filter press. The secondary bitumen- enriched solvent phase weighed 24.5 kg, including 6.5 kg of bitumen and 18.0 kg of primary solvent. The first solvent-wet tailings remained in the plate and frame filter press.

The first solvent-wet tailings remaining in the plate and frame filter press were cleaned of residual primary solvent and any remaining bitumen using a secondary lighter solvent of heptane. The fresh solution of secondary solvent was pumped into the plate and frame filter press across the first solvent-wet tailings at a secondary solvent to original bitumen weight ratio of 0.79:1. The plate and frame filter press was pressurized with inert atmosphere while the first solvent-second solvent mixture was collected at the outlet of the filter. The first solvent-second solvent mixture included 3.3 kg of bitumen and 19.0 kg of second solvent. The first solvent- second solvent mixture was sent to an evaporation separation process to recycle the secondary solvent. The second solvent-wet tailings remaining in the plate and frame filter press included 0.2 kg bitumen and 8 kg of secondary solvent.

The second solvent-wet tailings loaded in the plate and frame filter press were pressurized with heated inert gas to vaporize the residual secondary solvent and produce final solvent-dry, stackable tailings for discharge. After vaporization, the solvent-dry, stackable tailings had a total weight of 176.0 kg, including 0.2 kg bitumen and 0.1 kg secondary solvent.

Table 2 summarizes the measurements taken of various samples throughout the experiment.

Table 2 Mass Balance for Solvent Extraction of Bitumen in a Plate and Frame Filter Press Apparatus

Example 6. Semi-Continuous Countercurrent Washing Using a Vertical Column

A second bitumen extraction experiment was conducted using a vertical column. 600.0 kg of oil sand ore having a bitumen content of about 12 wt% was mixed with a primary solvent of Solvesso 150. The primary solvent to bitumen ratio was about 0.84:1. The primary solvent and oil sand ore was mixed for 15 minutes in a disaggregation device.

The ore/solvent mixture was removed from the disaggregation device and pumped to the top end of the vertical column. The vertical column was filled with the ore/solvent mixture until a bed of full height was formed, and the top end of the vertical column was then sealed. The vertical column had a height of 6 feet and a inner diameter of 22 inches. The vertical column was pressurized with an inert gas and the bitumen-enriched solvent phase was collected at the bottom end of the vertical column. The bitumen-enriched solvent phase weighed 75.3 kg, including 37.3 kg of bitumen and 38.0 kg of primary solvent. First solvent-wet tailings remained in the vertical column.

A fresh solution of primary solvent was pumped into the top end of the vertical column at a solvent to original bitumen weight ratio of 0.73:1. The vertical column was pressurized with inert atmosphere and the fresh primary solvent was forced through the first solvent-wet tailings in a plug flow 'washing' action. The secondary bitumen-enriched solvent phase was collected at the bottom end of the vertical column. The secondary bitumen-enriched solvent phase weighed 78 kg, including 25 kg of bitumen and 53 kg of primary solvent. The first solvent-wet tailings remained in the vertical column.

The first solvent-wet tailings remaining in the vertical column were cleaned of residual primary solvent and any remaining bitumen using a secondary lighter solvent of heptane. The fresh solution of secondary solvent was pumped into the top end of the vertical column at a secondary solvent to original bitumen weight ratio of 0.68:1. The vertical column was pressurized with inert atmosphere while the first solvent-second solvent mixture was collected at the bottom end of the vertical column. The first solvent-second solvent mixture included 9.8 kg of bitumen and 50.0 kg of second solvent. The first solvent-second solvent mixture was sent to a evaporation separation process to recycle the secondary solvent. The second solvent-wet tailings remaining in the vertical column included 0.4 kg bitumen and 49 kg of secondary solvent. The second solvent-wet tailings loaded in the vertical column were pressurized with heated inert gas to vaporize the residual secondary solvent and produce final solvent-dry, stackable tailings for discharge. After vaporization, the solvent-dry, stackable tailings had a total weight of 528.0 kg, including 0.4 kg bitumen and 0.2 kg secondary solvent.

Table 3 summarizes the measurements taken of various samples throughout the experiment.

Table 3 Mass Balance for Solvent Extraction of Bitumen in a Vertical Column Apparatus

Example 7. Continuous Countercurrent Washing Example Using a Screw Classifier

50.0 kg of oil sand ore containing about 11 wt% bitumen content was mixed with a primary solvent of Solvesso 150. The primary solvent was added to the oil sand ore at a primary solvent to original bitumen weight ratio of about 2.3:1. The oil sand ore and primary solvent were mixed for about 15 minutes in a disaggregation device.

The ore/solvent mixture was removed from the disaggregation device and a solid-liquid separation was performed in a settling device to drain the bitumen-enriched solvent phase from the first solvent-wet tailings. The first solvent-wet tailings contained around 7.3 wt% bitumen.

The bitumen-enriched solvent phase weighed 6.5 kg, including 2.0 kg bitumen and 4.5 kg primary solvent.

The first solvent-wet tailings were fed to a dewatering screw classifier. The first solvent- wet tailings were added to the dewatering screw classifier feed well at a rate of about 1 kg/minute with a maximum feed rate of about 1.2 kg/minute. The helical dewatering screw classifier pulled the first solvent- wet tailings up from the feed well to a discharge at the top of the dewatering screw classifier, while the liquid component of the first solvent- wet tailings drained back to form a pool and overflow at the feed box of the dewatering screw classifier.

Primary solvent was added approximately 1/3 of the distance up the dewatering screw classifier at a rate of 45 wt% of the feed mass. The primary solvent was delivered by spray nozzles. The primary solvent removed the remaining bitumen-enriched solvent phase from the first solvent-wet tailings as it flowed through the first solvent-wet tailings and down the apparatus, forming a pool at the bottom of the screw classifier and then overflowing into a product drum. The bitumen-enriched solvent phase weighed 25.7 kg, including 3.0 kg bitumen and 22.7 kg primary solvent.

The first solvent- wet tailings were discharged from the top of the apparatus and passed to a second dewatering screw classifier for secondary solvent washing. A second stage washing was conducted across a second dewatering screw classifier in the same manner as the primary wash using a lighter solvent to wash out the residual primary solvent and any remaining bitumen. The secondary solvent was heptane, and was added at a rate of about 35 wt% the feed mass. The first solvent-second solvent mixture included 0.3 kg bitumen and 2.2 kg secondary solvent.

The second solvent-wet tailings after the secondary washing stages were sent to a secondary solvent recovery stage to remove the secondary solvent. The second solvent- wet tailings included 0.0 kg of bitumen and 17.0 kg of secondary solvent. The secondary solvent was evaporated in a separate rotary drying stage to recover residual second solvent. The solvent- dry, stackable tailings produced after separating the second solvent had a total mass of 45.0 kg, including 0.1 kg of bitumen and 0.1 kg of secondary solvent. Table 4 summarizes the measurements taken of various samples throughout the experiment.

Table 4. Mass Balance for Solvent Extraction of Bitumen in Dewatering Screw Classifier

Example 8. Continuous Countercurrent Washing Example Using a Dewatering Screen

200.0 kg of oil sand ore containing about 12 wt% bitumen content was mixed with a primary solvent of Solvesso 150. The primary solvent was added to the oil sand ore at a primary solvent to original bitumen weight ratio of about 3.8:1. The oil sand ore and primary solvent were mixed for about 15 minutes in a disaggregation device.

The ore/solvent mixture was removed from the disaggregation device and a solid-liquid separation was performed in a settling device to drain the bitumen-enriched solvent phase from the first solvent-wet tailings. The first solvent-wet tailings contained 3 wt% bitumen. The bitumen-enriched solvent phase weighed 81.6 kg, including 17.6 kg bitumen and 64 kg primary solvent.

The first solvent-wet tailings were then passed directly to a dewatering screen having an aspect ratio of 1. A primary solvent was sprayed onto the dewatering screen at around 1/3 of the distance up the dewatering screen. The primary solvent was added at a rate of 35 wt% the feed mass. Bitumen-enriched solvent phase was collected into compartments under the dewatering screen. The bitumen-enriched solvent phase weighed 75.3 kg, including 5.3 kg bitumen and 70.0 kg primary solvent.

A secondary solvent was sprayed onto the dewatering screen at around 1/3 of the distance up the dewatering screen. The secondary solvent was heptane, and was added at a rate of 10 wt% the feed mass. First solvent-second solvent mixture was collected into compartments under the dewatering screen. The first solvent-second solvent included 1.0 kg bitumen and 4.0 kg secondary solvent.

The second solvent-wet tailings after the secondary washing stage were sent to a secondary solvent recovery stage to remove the secondary solvent. The second solvent- wet tailings included 0.1 kg of bitumen and 17.0 kg of secondary solvent. The secondary solvent was evaporated in a separate rotary drying stage to recover residual second solvent. The solvent- dry, stackable tailings produced after separating the second solvent had a total mass of 175.0 kg, including 0.1 kg of bitumen and 0.1 kg of secondary solvent. Table 5 summarizes the measurements taken of various samples throughout the experiment. Table 5. Mass Balance for Solvent Extraction of Bitumen Over a Dewatering Screen

* Countercurrent flow includes recycle bitumen from prior washings stages

In view of the many possible embodiments to which the principles of the disclosed invention may be applied, it should be recognized that the illustrated embodiments are only preferred examples of the invention and should not be taken as limiting the scope of the invention. Rather, the scope of the invention is defined by the following claims. We therefore claim as our invention all that comes within the scope and spirit of these claims.

Claims

CLAIMS What is claimed is:

1. A method comprising:

forming a first mixture by mixing a material comprising bitumen with a first solvent, wherein the first mixture comprises a bitumen-enriched solvent phase;

separating a first portion of the bitumen-enriched solvent phase from the first mixture by filtering or settling the first mixture; and

separating a second portion of the bitumen-enriched solvent phase from the first mixture by adding a second solvent to the first mixture.

2. The method as recited in claim 1, wherein the material comprising bitumen comprises less than 10 wt % bitumen.

3. The method as recited in claim 1, wherein the first portion of the bitumen-enriched solvent phase and the second portion of the bitumen-enriched solvent phase account for 90% or more of the bitumen-enriched solvent phase included in the first mixture.

4. The method as recited in claim 1, wherein adding the second solvent to the first mixture comprises washing the first mixture with the second solvent in a countercurrent fashion.

5. The method as recited in claim 1, further comprising loading the first mixture in a vertical column having a top end and a bottom end prior to separating the second portion of the bitumen-enriched solvent phase from the first mixture by adding a second solvent to the first mixture.

6. The method as recited in claim 5, wherein adding the second solvent to the first mixture comprises adding the second solvent to the first mixture at the top end of the vertical column.

7. The method as recited in claim 5, wherein the second quantity of bitumen-enriched solvent phase is collected at the bottom end of the vertical column.

8. The method as recited in claim 5, further comprising adding gas over the first mixture loaded in the vertical column.

9. The method as recited in claim 1, further comprising loading the first mixture into a plate and frame-type filter press prior to separating the second portion of the bitumen-enriched solvent phase from the first mixture by adding the second solvent to the first mixture.

10. The method as recited in claim 9, wherein adding the second solvent to the first mixture comprises introducing the second solvent into the first mixture loaded in the plate and frame-type filter press.

11. The method as recited in claim 9, further comprising adding gas over the first mixture loaded in the plate and frame-type filter press.

12. The method as recited in claim 1, wherein the first solvent comprises a light aromatic solvent.

13. The method as recited in claim 12, wherein the second solvent comprises light aromatic solvent.

14. The method as recited in claim 13, wherein the first solvent and the second solvent comprise the same light aromatic solvent.

15. The method as recited in claim 12, wherein the second solvent comprises a volatile hydrocarbon solvent.

16. The method as recited in claim 12, wherein the second solvent comprises a polar solvent.

17. The method as recited in claim 16, wherein the polar solvent comprises an oxygenated hydrocarbon compound.

18. The method as recited in claim 12, wherein the light aromatic solvent comprises kerosene, diesel, gas oil, naphtha, benzene, toluene, an aromatic alcohol, derivatives thereof, or a combination thereof.

19. The method as recited in claim 1, wherein the material comprising bitumen comprises tar sands.

20. The method as recited in claim 1, wherein forming the first mixture by mixing the material comprising bitumen with the first solvent comprises mixing the material comprising bitumen and the first solvent for a period of from 5 seconds to 60 minutes.

21. The method as recited in claim 1, wherein mixing the material comprising bitumen with the first solvent comprises low intensity blending.

22. The method as recited in claim 1, wherein the amount of first solvent mixed with the material comprising bitumen is from 0.5 to 6.0 times the amount of bitumen by volume in the material comprising bitumen.

23. The method as recited in claim 1, wherein the amount of second solvent added to the first mixture is from 10% to 400% of the amount of first solvent mixed with the material comprising bitumen.

24. The method as recited in claim 1, further comprising:

upgrading a bitumen component of the first portion of the bitumen-enriched solvent phase or the second portion of the bitumen-enriched solvent phase.

25. A method comprising:

mixing a material comprising bitumen with a first solvent;

filtering or settling a first portion of the bitumen-enriched solvent phase from the first result of mixing the material comprising bitumen with the first solvent; and

adding a second solvent to a second result of filtering or settling the first portion of the bitumen-enriched solvent phase from the first result.

26. The method as recited in claim 25, wherein the material comprising bitumen comprises less than 10 wt % bitumen.

27. The method as recited in claim 25, wherein the first solvent comprises a light aromatic solvent.

28. The method as recited in claim 27, wherein the second solvent comprises a light aromatic solvent.

29. The method as recited in claim 28, wherein the first solvent and the second solvent comprise the same light aromatic solvent.

30. The method as recited in claim 27, wherein the second solvent comprises a volatile hydrocarbon solvent.

31. The method as recited in claim 27, wherein the second solvent comprises a polar solvent.

32. The method as recited in claim 25, wherein the material comprising bitumen comprises tar sands.

33. The method as recited in claim 25, further comprising:

upgrading a bitumen component of the first portion of the bitumen-enriched solvent phase or a bitumen component of a third result of adding a second quantity of first solvent to the second result.

34. A method comprising:

forming a first mixture by mixing a material comprising bitumen with a first quantity of first solvent, wherein the first mixture comprises a bitumen-enriched solvent phase;

separating the bitumen-enriched solvent phase from the first mixture and thereby producing first solvent-wet tailings, wherein the first solvent-wet tailings comprise a first solvent component; separating the first solvent component from the first solvent-wet tailings by adding a second solvent to the first solvent-wet tailings and thereby producing second solvent-wet tailings, wherein the second solvent-wet tailings comprise a second solvent component; and

separating the second solvent component from the second solvent-wet tailings and thereby forming solvent-dry, stackable tailings.

35. The method as recited in claim 34, wherein separating the bitumen-enriched solvent phase from the first mixture comprises:

separating a first quantity of the bitumen-enriched solvent phase from the first mixture by filtering, settling or draining the bitumen-enriched solvent phase from the first mixture; and

separating a second quantity of the bitumen-enriched solvent phase from the first mixture by adding a second quantity of first solvent to the first mixture.

36. The method as recited in claim 35, wherein separating the second quantity of the bitumen-enriched solvent phase from the first mixture comprises washing the first mixture with the second quantity of first solvent in a countercurrent process.

37. The method as recited in claim 34, wherein separating the first solvent component from the first solvent-wet tailings comprises washing the first solvent-wet tailings with the second solvent in a countercurrent process.

38. The method as recited in claim 34, wherein separating the second solvent from the second solvent-wet tailings comprises flashing the second solvent component from the second solvent-wet tailings.

39. The method as recited in claim 34, wherein the first solvent comprises a light aromatic solvent.

40. The method as recited in claim 39, wherein the light aromatic solvent comprises kerosene, diesel, gas oil, naphtha, benzene, toluene, an aromatic alcohol, derivatives thereof, or a combination thereof.

41. The method as recited in claim 34, wherein the second solvent comprises a volatile hydrocarbon solvent.

42. The method as recited in claim 41, wherein the volatile hydrocarbon solvent comprises a cyclo- or iso-paraffm having between 3 and 9 carbons, derivatives thereof, or combinations thereof.

43. The method as recited in claim 34, wherein the second solvent comprises liquefied petroleum gas.

44. The method as recited in claim 34, wherein separating the bitumen-enriched solvent phase from the first mixture comprises filtering the first mixture in a plate and frame-type filter press.

45. The method as recited in claim 34, wherein separating the first solvent component from the first solvent-wet tailings comprises filtering the first solvent-wet tailings in a plate and frame-type filter press.

46. The method as recited in claim 44, wherein filtering the first mixture in a plate and frame-type filter press further comprises adding a gas over the first mixture loaded in the plate and frame-type filter press.

47. The method as recited in claim 45, wherein filtering the first solvent- wet tailings in a plate and frame-type filter press further comprises adding a gas over the first solvent-wet tailings loaded in the plate and frame-type filter press.

48. The method as recited in claim 34, wherein the material comprising bitumen comprises tar sands.

49. The method as recited in claim 34, wherein the solvent-dry, stackable tailings comprise less than 0.1 wt% first solvent and second solvent.

50. A method comprising:

forming a first mixture by mixing material comprising bitumen with a first quantity of solvent;

loading the first mixture in a vertical column having a top end and bottom end;

injecting a second quantity of first solvent into the first mixture loaded in the vertical column at the top end of the vertical column;

collecting a bitumen-enriched solvent phase at the bottom end of the vertical column; injecting a first quantity of second solvent into the first mixture loaded in the vertical column at the top end of the vertical column;

collecting a first solvent-enriched second solvent phase at the bottom end of the vertical column; and

discharging the first mixture from the vertical column..

51. The method as recited in claim 50, further comprising adding a gas over the top end of the vertical column prior to injecting the second quantity of first solvent.

52. The method as recited in claim 50, further comprising adding a gas over the top end of the vertical column after injecting the second quantity of first solvent and prior to injecting the first quantity of second solvent.

53. The method as recited in claim 50, further comprising adding a gas over the top end of the vertical column after injecting the first quantity of second solvent.

54. The method as recited in claim 50, wherein the first solvent comprises a light aromatic solvent.

55. The method as recited in claim 54, wherein the light aromatic solvent comprises kerosene, diesel, gas oil, naphtha, benzene, toluene, an aromatic alcohol, derivatives thereof, or a combination thereof.

56. The method as recited in claim 50, wherein the second solvent comprises a volatile hydrocarbon solvent.

57. The method as recited in claim 56, wherein the volatile hydrocarbon solvent comprises a cyclo- or iso-paraffm having between 3 and 9 carbons, derivatives thereof, or combinations thereof.

58. The method as recited in claim 50, wherein the second solvent comprises liquefied petroleum gas.

59. The method as recited in claim 50, wherein the material comprising bitumen comprises tar sands.

60. The method as recited in claim 50, further comprising separating a residual amount of second solvent from the first mixture prior to discharging the first mixture from the vertical column.

61. The method as recited in claim 50, further comprising separating a residual amount of second solvent from the first mixture after discharging the first mixture from the vertical column.

62. The method as recited in claim 60, wherein separating a residual amount of second solvent from the first mixture comprises injecting a heated gas into the first mixture to evaporate the residual second solvent.

63. The method as recited in claim 61, wherein separating a residual amount of second solvent from the first mixture comprises injecting a heated gas into the first mixture to evaporate the residual second solvent.

64. Solvent-dry, stackable tailings produced by the method recited in claim 34.

65. Solvent-dry, stackable tailings produced by the method recited in claim 50.

66. A method comprising:

mixing a material comprising bitumen with a first quantity of first solvent; separating a bitumen-enriched solvent phase from a first result of mixing the material comprising bitumen with the first quantity of first solvent mixture;

separating a first solvent component from a second result of separating the bitumen- enriched solvent phase from the first result; and

separating a second solvent component from a third result of separating the first solvent component from the second result.

67. The method as recited in claim 66, wherein separating the bitumen-enriched solvent phase from the first result of mixing the material comprising bitumen with the first quantity of first solvent mixture comprises:

filtering, settling or draining a first quantity of bitumen-enriched solvent phase from the first result of mixing the material comprising bitumen with the first quantity of first solvent mixture; and

adding a second quantity of first solvent to the first result of mixing the material comprising bitumen with the first quantity of first solvent mixture.

68. A method comprising:

mixing material comprising bitumen with a first quantity of solvent;

loading a first result of mixing material comprising bitumen with a first quantity of solvent in a vertical column having a top end and bottom end;

injecting a second quantity of first solvent into the first result loaded in the vertical column at the top end of the vertical column; collecting a bitumen-enriched solvent phase at the bottom end of the vertical column; injecting a first quantity of second solvent into the first result loaded in the vertical column at the top end of the vertical column;

discharging the first result from the vertical column..

69. The method as claimed in claim 34, further comprising:

upgrading a bitumen component of the bitumen-enriched solvent phase.

70. The method as claimed in claim 50, further comprising:

upgrading a bitumen component of the bitumen-enriched solvent phase.

71. The method as claimed in claim 66, further comprising:

upgrading a bitumen component of the bitumen-enriched solvent phase.

72. The method as claimed in claim 68, further comprising:

upgrading a bitumen component of the bitumen-enriched solvent phase.