Methods for extracting bitumen from bituminous material   

Abstract: Methods for preparing solvent-dry, stackable tailings. The method can include the steps of adding a first quantity of solvent to a bitumen material to form a first mixture, separating a first quantity of bitumen-enriched solvent from the first mixture and thereby creating solvent-wet tailings, and adding a quantity of water to the solvent-wet tailings to separate a solvent component from the solvent-wet tailings and thereby forming solvent-dry, stackable tailings. The solvent used in the methods can include paraffinic solvent, such as pentane.

This application claims priority to U.S. Provisional Patent Application No. 61/511,913, filed Jul. 26, 2011, and U.S. Provisional Patent Application No. 61/525,582, filed Aug. 19, 2011. Each application is incorporated herein by reference in its entirety.

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

As noted above, oil sands represent one of the well known sources of bitumen. Oil sands typically include bitumen, water, and mineral solids. The mineral solids can include inorganic solids such as coal, sand, and clay. Oil sand deposits can be found in many parts of the world, including North America. One of the largest North American oil sands deposits is in the Athabasca region of Alberta, Canada. In the Athabasca region, the oil sands formation can be found at the surface, although it may be buried two thousand feet below the surface overburden or more.

Oil sands deposits can be measured in barrels equivalent of oil. The Athabasca oil sands deposit has been estimated to contain the equivalent of about 1.7 to 2.3 trillion barrels of oil. Global oil 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 oil sands may vary 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 can require extracting the bitumen from the naturally occurring geological material. In the case of oil sands, this may include separating the bitumen from the mineral solids and other components of oil sands.

One conventional process for separating bitumen from mineral solids and other components of oil sands includes mixing the oil 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 from the oil sands and allows air bubbles to attach to the released bitumen droplets. These air bubbles float to the top of the mixture and form a bitumen-enriched froth. The froth can include 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 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. The tailings stream can also include 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.

Tailings produced by the hot water process and/or the froth treatment process can pose several problems. Firstly, as noted above, the tailings produced by conventional methods can include solvents, precipitated asphaltenes, 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 can 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 these materials present environmental risks. This can 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 chemical and physical problems. In some circumstances, the total volume of the tailings produced by the conventional methods may be more than the volume of mined oil 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 problems. The conventional methods sometimes 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 can have a sludge-like consistency that may last indefinitely. The sludge-like consistency means that the tailings are not stackable, thereby 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 can be 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.

SUMMARY

Disclosed are embodiments of a method for producing solvent-dry, stackable tailings, and the solvent-dry, stackable tailings produced therefrom.

In some embodiments, a method of extracting bitumen from bituminous material is disclosed. The method includes passing a solvent through a first quantity of bituminous material and passing water through the first quantity of bituminous material. The solvent can be a paraffinic solvent. The method can produce solvent-dry tailings due at least in part to the inclusion of a water wash step that is capable of effectively removing solvent from the tailings produced during the process. The solvent-dry tailings are beneficial because they are easier to dispose of from an environmental standpoint.

In some embodiments, a method for extracting bitumen from bituminous material is disclosed. The method includes mixing solvent with bituminous material and forming a mixture, separating the mixture into a bitumen-enriched solvent phase and a bitumen-depleted tailings phase, and passing water through the bitumen-depleted tailings phase. The solvent can be a paraffinic solvent. The method can produce solvent-dry tailings due at least in part to the inclusion of a water wash step that is capable of effectively removing solvent from the tailings produced during the process. The solvent-dry tailings are beneficial because they are easier to dispose of from an environmental standpoint.

In some embodiments, a method for extracting bitumen from bituminous material is disclosed. The method includes contacting a bituminous material with a solvent and forming solvent-wet bituminous material, and contacting the solvent-wet bituminous material with water and forming a water-wet bituminous material. The solvent can be a paraffinic solvent. The method can produce solvent-dry tailings due at least in part to the inclusion of a water wash step that is capable of effectively removing solvent from the tailings produced during the process. The solvent-dry tailings are beneficial because they are easier to dispose of from an environmental standpoint.

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.

Thus, 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 therefore also 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:

FIG. 1 is a flow chart detailing a method for producing solvent-dry, stackable tailings as disclosed herein;

FIG. 2 is a schematic diagram for a system and method for producing solvent-dry, stackable tailings as disclosed herein;

FIG. 3 is a schematic diagram for a system and method for producing solvent-dry, stackable tailings as disclosed herein; and

FIG. 4 is a schematic diagram for a system and method for producing solvent-dry, stackable tailings as disclosed 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” may include one or more than one individual solvent compounds 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 “oil sands” includes oil sands. The separations described herein can be partial, substantial or complete separations unless indicated otherwise. All percentages recited herein are volume percentages unless indicated otherwise.

Oil sands are used throughout this disclosure as a representative bitumen material. However, the methods and systems disclosed herein are not limited to processing of oil sands. Applicant believes that any bitumen material may be processed by the methods and systems disclosed herein.

With reference to FIG. 1, one embodiment of a method for producing solvent-dry, stackable tailings includes a step 100 of adding a first quantity of solvent to a bitumen material 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 adding a quantity of water to the remaining portion of the first mixture, which can be considered solvent-wet tailings.

Step 100 of adding a first quantity of solvent to bitumen material to form a first mixture represents a step in the solvent extraction process (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 bitumen material is mixed with one or more solvents to dissolve bitumen in the solvent and thereby separate it from the other components of the bitumen material (e.g., the mineral solids of oil sands).

The solvent used in step 100 can include a hydrocarbon solvent. Any suitable hydrocarbon solvent or mixture of hydrocarbon solvents that is capable of dissolving bitumen can 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 solvent is a paraffinic solvent. Any paraffinic solvent suitable for use in dissolving bitumen can be used. In some embodiments, the paraffinic solvent is pentane. Other suitable paraffinic solvents include, but are not limited to, ethane, butane, hexane and heptane

The solvent added into the bitumen material in step 100 need not be 100% solvent. Other components can be included with the solvent when it is added into the bitumen material. In some embodiments, the solvent added into the column includes a bitumen content. Solvent including a bitumen content can be referred to as bitumen-enriched solvent, dissolved bitumen (“disbit”), or diluted bitumen (“dilbit”). Bitumen-enriched solvent can be obtained from bitumen extraction processes where a solvent has already been used to extract bitumen from bitumen material. In some embodiments, the bitumen-enriched solvent is bitumen-enriched solvent separated from the first mixture in step 110 described in greater detail below and recycled back within the method for use in step 100.

The bitumen material used in step 100 can be any material that includes bitumen. In some embodiments, the bitumen material includes any material having more than 3 wt % bitumen. Exemplary bitumen materials include, but are not limited to, oil sands, black shales, coal formations, and hydrocarbon sources contained in sandstones and carbonates. The bitumen material can be obtained by any known methods for obtaining bitumen material, such as by surface mining.

In some embodiments, the bitumen material is subjected to one or more pretreatment steps prior to being mixed with the solvent. Any type of pretreatment step that will promote mixing between the solvent and bitumen material and/or promote extraction of bitumen from the bitumen material can be used. In some embodiments, the pretreatment step involves heating the bitumen material. In some embodiments, the bitumen material is heated to a temperature in the range of from 30° C. to 75° C. Any manner of heating the bitumen material can be used in the pretreatment step. In some embodiments, the bitumen material is heated by adding steam to the bitumen material. Immersed or external heaters can also be used to heat the bitumen material.

While some embodiments include a bitumen material heating pretreatment step as described above, other embodiments specifically exclude any bitumen material heating pretreatment steps. In such embodiments, the bitumen material is mixed with the solvent at the naturally occurring temperature of the bitumen material prior to mixing. The method can thereby eliminate the cost associated with heating the bitumen and simplify the overall method. In some embodiments the solvent is heated or retains heat from the previous recovery steps in recovering solvent from the bitumen.

The step of adding a first quantity of solvent to the bitumen material to form a 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.

The solvent can be added to the bitumen material by any suitable manner for ultimately forming a mixture of the two components. For example, the solvent can be added to the bitumen material by mixing the two components together. The mixing of the bitumen material and the solvent is preferably carried out to the point of dissolving most, if not all, of the bitumen contained in the bitumen material. In some embodiments, the bitumen material and the solvent are 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 can also contain mechanisms for stirring and mixing solvent and bitumen material to further promote dissolution of the bitumen in the 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 bitumen material and the first solvent, such as shown in U.S. Pat. No. 5,474,397.

In certain embodiments, bitumen material and the solvent are mixed by virtue of the manner in which the bitumen material and the solvent are introduced into the vessel. That is to say, the solvent is introduced into a vessel already containing bitumen material at a high velocity, thereby effectively agitating and mixing the contents of the vessel. Conversely, the bitumen material can be introduced into a vessel already containing solvent.

In some embodiments the bitumen material and solvent are mixed by introducing the solvent at a bitumen crushing stage that takes place upstream of the main mixing step and which is aimed at reducing the size of the bitumen material. The solvent can be added to the bitumen material either in the crusher or prior to or after the crusher. Further mixing can be undertaken during transport of the mixture from the crusher to subsequent processing steps (e.g., by pumping the mixture and transporting the mixture in a pipeline).

The amount of the solvent added to the bitumen material can be a sufficient amount to effectively dissolve at least a portion, or desirably all, of the bitumen in the bitumen material. In some embodiments, the amount of the solvent mixed with the bitumen material is approximately 0.5 to 4.0 times the amount of bitumen by volume contained in the bitumen material, approximately 0.75 to 3.0 times the amount of the bitumen by volume contained in the bitumen material, or preferably approximately 1.0 to 2.0 times the amount of bitumen by volume contained in the bitumen material.

It should be noted that the ratio of the solvent to bitumen can be affected by the amount of bitumen in the bitumen material. For example, more solvent may be required for lower grade oils sands ore (e.g., 6 wt % bitumen) than for average grade oil sands ore (e.g., between 9 wt % and 14 wt % bitumen). Conversely, very high grade oil sands ore (e.g., greater than 15 wt % bitumen) may require a higher solvent to bitumen ratio again.

The first mixture of the solvent and the bitumen material generally includes bitumen-enriched solvent, with the majority of the bitumen from the bitumen material dissolved in the bitumen-enriched solvent phase. In some embodiments, 90%, preferably 95%, and most preferably 99% or more of the bitumen in the bitumen material is dissolved in the solvent and becomes part of the bitumen-enriched solvent. In some embodiments, the solvent may be light enough to precipitate asphaltenes as a means to reject the heavy portion of the bitumen within the bitumen material. In such embodiments the total bitumen dissolved will be lower by virtue of the asphaltene component rejection.

The bitumen-enriched solvent is separated from the first mixture at step 110. Separation of the bitumen-enriched solvent from the first mixture may result in the first mixture becoming solvent-wet tailings when a portion of the solvent remains behind in the primarily non-bituminous components of the first mixture after separation of bitumen-enriched solvent. Any suitable process for separating the bitumen-enriched solvent from the first mixture can be used, such as by filtering bitumen-enriched solvent from the first mixture (including but not limited to filtration via an automatic pressure filter, vacuum filtration, pressure filtration, and crossflow filtration), settling the first mixture and decanting bitumen-enriched solvent off the top of the settled mixture, by gravity or gas overpressure drainage of the bitumen-enriched solvent from the first mixture, or by displacement washing of the bitumen-enriched solvent from the first mixture. Any of these separation methods can be used alone or in combination to separate bitumen-enriched solvent from the first mixture.

In some embodiments, the bitumen-enriched solvent removed from the first mixture includes from about 5 wt % to about 50 wt % of bitumen and from about 50 wt % to about 95 wt % of the solvent. The bitumen-enriched solvent may include little or no non-bitumen components of the bitumen material (e.g., mineral solids). The solvent-wet tailings created by removing the bitumen-enriched solvent from the first mixture can include from about 75 wt % to about 95 wt % non-bitumen components and from about 5 wt % to about 25 wt % solvent. The solvent component of the solvent-wet tailings represents solvent mixed with the bitumen material but which is not removed from the first mixture during separation step 110. This solvent component of the solvent-wet tailings can have bitumen dissolved therein. Accordingly, in some embodiments, the solvent-wet tailings includes from about 1 wt % to about 5 wt % of bitumen.

The vessel for mixing mentioned previously can function as both a mixer and a separator for separating the bitumen-enriched solvent 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 is divided into sections. One section may be used to mix the bitumen material and the solvent and another section may be used to separate the bitumen-enriched solvent from the first mixture.

The separation of the bitumen-enriched solvent 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 from the first mixture by any of the above-mentioned methods can be preceded or followed by applying pressurized gas over the first mixture. Applying a pressurized gas over the first mixture can facilitate the separation of the bitumen-enriched solvent from the non-bitumen components of the solvent-wet tailings. Bitumen-enriched solvent entrained between solid sand particles can then be removed by applying additional solvent to the solvent-wet tailings as described in greater detail below. The addition of additional solvent can displace the liberated bitumen-enriched solvent from the solvent-wet tailings by providing a driving force across a filtration element (i.e., the non-bituminous components of the bitumen material). Any suitable gas capable of displacing solvent can be used. In some embodiments, the gas is nitrogen, carbon dioxide, or steam. In some embodiments the pressurized gas may be solvent vapor or superheated solvent of the same solvent that is used in the dissolution stage. The gas can 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 bitumen material is used. This is equivalent to a range of about 4.5 liters to 27 liters of gas per liter of bitumen material. In certain embodiments, 3.5 ft3 of gas per ton of bitumen material is used.

Bitumen-enriched solvent separated during step 110 can be subjected to further processing to separate the solvent from the bitumen. Any suitable method of separating the two components can be used. In some embodiments, the bitumen-enriched solvent is heated to a temperature above the boiling temperature of the solvent, resulting in the solvent evaporating off of the bitumen. The evaporated solvent can be collected, condensed, and recycled back in the extraction process.

After bitumen-enriched solvent has been separated from the first mixture and solvent-wet tailings have been produced as a result, a step 120 of adding a quantity of water to the solvent-wet tailings is carried out in order to remove solvent from the solvent-wet tailings. Addition of the water can displace the solvent component and force the solvent out of the solvent-wet tailings. As noted above, the solvent-wet tailings can include from about 5 wt % to about 20 wt % of the solvent, and it is desirable to remove this solvent from the tailings to make the tailings more environmentally friendly. In some embodiments, the solvent also has some bitumen dissolved therein, which will also be displaced from the solvent-wet tailings.

Any manner of adding water to the solvent-wet tailings that results in displacement of solvent from the solvent-wet tailings can be used. In some embodiments, the manner in which the water is added to the solvent-wet tailings is similar or identical to the manner in which the first solvent is added to the first mixture.

In some embodiments, water with an elevated temperature (i.e., above room temperature) or steam is used to displace solvent from solvent wet tailings. Water with an elevated temperature can preferably be at a temperature greater than the boiling point temperature of the solvent. When water at an elevated temperature or steam is used, the introduction of the water or steam into the solvent-wet tailings can serve to both displace the solvent and remove solvent via evaporation. For example, steam may rapidly condense once introduced into the solvent-wet tailings and transfer heat to the solvent, resulting in solvent evaporation. Water at an elevated temperature can be added with the solvent-wet tailings in the same manner as water at room temperature. Steam can be injected into the solvent-wet tailings. Any manner for injecting steam into the solvent-wet tailings can be used. In some embodiments, injection lines are inserted into the solvent-wet tailings through which steam can be injected into the solvent-wet tailings.

The amount of the water or steam added to the solvent-wet tailings can be sufficient to effectively displace and/or evaporate at least a portion, or desirably all, of the solvent in the solvent-wet tailings. The amount of water added to the solvent-wet tailings can be approximately 0.5 to 4 times the amount of bitumen by volume originally contained in the bitumen material. The amount of steam added to the solvent-wet tailings can be approximately less than or equal to 2 times the amount of bitumen by volume originally contained in the bitumen material.

In some embodiments, the water is added in two or more stages, with the water being in the same or different phases for each stage. For example, in some embodiments, a first stage addition of water includes the addition of water in a liquid phase, and a second stage addition of water includes the addition of steam. When water in a liquid phase is used for any stage, the water can be at any suitable temperature, including water at elevated temperatures.

In some embodiments, the addition of water to the solvent-wet tailings results in the removal of 95% or more of the solvent in the solvent-wet tailings. The solvent can leave the solvent-wet tailings as a solvent-water mixture. The solvent-water mixture can include from about 10 wt % to about 40 wt % solvent and from about 60 wt % to about 90 wt % water. The mixture of water and solvent can be collected and separated so that the water and solvent can be reused in the extraction method. Any suitable method for separating the water and solvent can be used. In some embodiments, the water and solvent are separated based on differences in boiling temperatures.

As with previously described separation steps, separation of the solvent from the solvent-wet tailings by adding water can be preceded or followed by applying pressurized gas over the solvent-wet tailings. Applying a pressurized gas over the solvent-wet tailings can facilitate the separation of the solvent component of the solvent-wet tailings from the non-bitumen components of the solvent-wet tailings. The liberated solvent can then be displaced from the solvent-wet tailings by applying additional water to the solvent-wet tailings. The application of a gas overpressure can also displace solvent from the solvent-wet tailings by providing a driving force across a filtration element (i.e., the non-bituminous components of the solvent-wet tailings). Any suitable gas for displacing solvent can be used. In some embodiments, the gas is nitrogen, carbon dioxide or steam. The gas can also be added over the mixture in any suitable amount. In some embodiments, 1.8 m3 to 10.6 m3 of gas per ton of bitumen material is used. This is equivalent to a range of about 4.5 liters to 27 liters of gas per liter of bitumen material. In certain embodiments, 3.5 ft3 of gas per ton of bitumen material is used.

The solvent-dry, stackable tailings resulting from removal of the solvent from the solvent-wet tailings generally include inorganic solids, such as sand and clay, water, and little to no 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 can create damp tailings that will not produce dust when transporting or depositing the tailings. This range of water content can also provide stackable tailings that will not flow like dry sand, and therefore have the ability to be retained within an area without the need for retaining structures (e.g., a tailings pond). This range of water content can 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 can also include less than 2 wt % bitumen (or greater if asphaltenes are rejected).

Generally speaking, the above-described process can be considered advantageous over the previously known hot water bitumen extraction process because water is used to remove solvent rather than to extract bitumen from bitumen material. Avoiding the use of water to extract bitumen can mitigate or eliminate many of the problems discussed in greater detail above.

In some embodiments, the above described method may be carried with the use of a plate and frame-type filter press. After performing step 100 of mixing solvent with bitumen material, the first mixture may be loaded into a plate and frame-type filter press, at which point steps 110 and 120 may be carried out.

The plate and frame-type filter press may be any suitable type of plate and frame-type filter press, including both vertical and horizontal plate and frame-type filter presses. An exemplary vertical plate and frame-type filter press suitable for use in this method is described in U.S. Pat. No. 4,222,873. An exemplary horizontal plate and frame-type filter press suitable for use in this method is described in U.S. Pat. No. 6,521,135. Generally, the first mixture may be pumped into frame chamber located between two filter plates. The first mixture fills the frame chamber and, as the frame chamber becomes fully occupied by the first mixture, separation step 110 takes place as liquid bitumen-enriched solvent migrates out of the frame chamber through the filter cloths of each filter plate. The solid material of the first mixture remains behind in the frame chamber.

Separation of the bitumen-enriched solvent from the first mixture may also take place by adding additional solvent into the filter press after loading the first mixture into the frame chamber. The additional solvent pumped into the frame chamber may serve to displace bitumen-enriched solvent from the frame chamber and through the filter cloths. Any suitable amount of additional solvent that will displace bitumen-enriched solvent from the frame chamber may be introduced into the frame chamber. The solvent may be the same solvent used when forming the first mixture in step 100 or may be another type of solvent as described in greater detail above.

The addition of water to separate solvent can proceed in a similar or identical fashion to the addition of solvent into the frame chamber as described above. The addition of water into the frame chamber loaded with solvent-wet tailings can displace solvent through the filter cloths and out of the frame chamber.

When utilizing a filter press to carry out the method described herein, pressurized gas can be injected into the frame chamber before or after the addition of the first mixture, the solvent, or the water. The addition of the pressurized gas can help promote the separation of the materials targeted for separation by, e.g., liberating the material from the mineral solids so that it may more freely be removed upon subsequent addition of a displacement liquid. The introduction of pressurized gas into the frame chamber can proceed according to the details provided above for applying pressurized gas over a first mixture.

In some embodiments, the above described method is carried out by utilizing countercurrent washing. After step 100 of adding solvent to bitumen material to form a first mixture, the 110 and 120 can take place by moving the various materials through each other in opposite directions. For example, with respect to step 110, the separation step can be carried out by performing a countercurrent washing process where solvent traveling in one direction is passed through the first mixture traveling in an opposite direction. In some embodiments, the first mixture is loaded at the bottom of a screw classifier conveyor positioned at an incline, while a second quantity of 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 quantity of solvent flows down the inclined screw classifier conveyor and passes through the first mixture. The second quantity of solvent can displace bitumen-enriched solvent contained in the first mixture, thereby “washing” the bitumen-enriched solvent from the first mixture.

Separation of the bitumen-enriched solvent and the first mixture may naturally occur based on the configuration of the screw classifier conveyor, with the predominantly liquid bitumen-enriched solvent collecting at one end of the washing unit and the predominantly solid solvent-wet tailings at the opposite end of the washing unit. For example, when an inclined screw classifier conveyor is used, the bitumen-enriched solvent can collect at the bottom of the screw classifier conveyor, while the solvent-wet tailings can collect at the top of the screw classifier conveyor. The bitumen-enriched solvent can include predominantly bitumen and solvent.

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

Steps 120 can be carried out in a similar fashion. The solvent-wet tailings obtained after washing the first mixture in a countercurrent process can be subjected to a countercurrent washing with water. As the water passes through the solvent-wet tailings traveling in an opposite direction, the water displaces the solvent.

In some embodiments, the above described method is carried out by utilizing a vertical column. The first mixture prepared in step 100 can be loaded in a vertical column. Any method of loading the first mixture in the vertical column can be used. The first mixture can be poured into the vertical column or, when an appropriate first mixture viscosity is obtained from mixing step 100, the first mixture can be pumped into the vertical column. First mixture can 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 can be blocked, such as by a removable plug, 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 is used to maintain the first mixture in the vertical column. Accordingly, introducing first mixture at the top end of the vertical column can fill the vertical column with first mixture. In some embodiments, the vertical column is free of any obstructions, such as platforms or stages. 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 is added to the vertical column to occupy 90% or more of the volume of the vertical column. In some embodiments, the first mixture is not filled to the top of the vertical column so that room is provided to inject first solvent, second solvent, etc., into the vertical column.

In some embodiments, a pre-loading separation step is carried out after the mixture has been prepared in step 100 but before the mixture is loaded in the vertical column. The pre-loading separation step can include separating a liquid component of the first mixture from the first mixture. The liquid component can include a quantity of the bitumen-enriched solvent that is produced upon mixing the solvent and the bitumen material to form the first mixture. Because this liquid component is accessible immediately upon formation of the first mixture and relatively easy to separate from the first mixture using basic separation techniques, it can be separated from the first mixture prior to performing the further separation steps that occur in the vertical column and which are primarily aimed at separating the more inaccessible quantities of the bitumen-enriched solvent included in the first mixture.

The liquid component of the first mixture can be separated from the first mixture prior to loading the first mixture in the column by any suitable separation method capable of separating a liquid component from a first mixture. In some embodiments, any type of filtration process can be used wherein the liquid component passes through a filtration medium that does not allow solid particles of a certain size to pass therethrough. Accordingly, when filtration is performed, the liquid component including bitumen-enriched solvent passes through the filter while bitumen material having some bitumen-enriched solvent entrained therein will not pass through the medium. In other embodiments, the liquid component is separated by decanting the first mixture. When contained within a vessel, the first mixture can include a liquid component that resides above the bitumen material. Accordingly, the liquid component can be poured or skimmed off the top of the first mixture to separate the liquid component from the remainder of the first mixture.

In some embodiments where this pre-loading separation step is carried out, the amount of solvent added to the bitumen material to form the first mixture is more than is added when a pre-loading separation step is not performed. The aim of adding this higher amount of solvent is to create a liquid component that is plentiful in the first mixture and relatively easy to access for purposes of separation from the first mixture. In some embodiments, an amount 1.5 to 3 times the typical amount of solvent is used to ensure that the pre-loading separation step may be carried out.

As mentioned previously, the solvent used in step 100 to form the first mixture can be dilbit. In some embodiments, the solvent used to form the first mixture is preferably paraffinic-based dilbit when a pre-loading separation step is to be carried out.

As noted above, the column can have a generally vertical orientation. The vertical orientation can include aligning the column substantially perpendicular to the ground, but also can include orientations where the column forms angles less than 90° with the ground. The column can generally be oriented at any angle that results in gravity aiding the flow of the solvent and water from one end of the column to the other. In some embodiments, the column is oriented at an angle anywhere within the range of from about 1° to 90° with the ground. In a preferred embodiment, the column is 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 can be used. The material can also preferably be a non-porous material such that various liquids injected into the vertical column only exit the column from one of the ends of the vertical column. The material can 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 can have two ends opposite one another, designated a top end and a bottom end. The cross-section of the vertical column can be any shape, such as a circle, oval, square or the like. The cross-section of the vertical column can change along the height of the column, including both the shape and size of the vertical column cross-section. The vertical column can be a straight line vertical column having no bends or curves along the height of the vertical column. Alternatively, the vertical column can include one or more bends or curves. In some embodiments, the interior chamber of the vertical column is free of obstructions, such as platforms or stages.

Any dimensions can 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 ranges from 0.5:1 to 15:1.

Once first mixture is loaded in the vertical column, the separation and addition steps 110 and 120 are carried out. With respect to step 110, separation of the bitumen-enriched solvent from the mixture loaded in the column can be accomplished by adding a second quantity of solvent into the vertical column. The second quantity of solvent can be added into the vertical column at either the top end of the column (down flow mode) or the bottom end of the column (up flow mode). When a down flow mode is used, the second quantity of solvent flows downwardly through the first mixture loaded in the column. As the second quantity of solvent flows downwardly through the column, it can displace bitumen-enriched solvent from the column. When an up flow mode is used, the second quantity of solvent flows upwardly through the first mixture loaded in the column. As the second quantity of solvent flow upwardly through the column, it can dissolve further bitumen contained in the first mixture and displace bitumen-enriched solvent in the first mixture. A gas overpressure as described in greater detail above, can then be used to displace the dissolved bitumen and solvent back down through the first mixture and out of the column.

The second quantity of solvent can be added into the vertical column by any suitable method. In some embodiments, the second quantity of solvent is poured or pumped into the vertical column at the top end and allowed to flow down through the first mixture loaded therein under the influence of gravity. In some embodiments, the second quantity of the solvent is pumped into the column from the bottom end of the column. External pressures can also be added to promote the downward flow of the solvent after it has been added into the vertical column.

In some embodiments, the second quantity of solvent is added to the vertical column under flooded conditions. In other words, more solvent is 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 addition into the column in a down flow mode, the solvent can flow downwardly through the height of the column via small void spaces in the first mixture. The solvent can 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 solvent can travel the flow of least resistance through the first mixture. As the solvent flows downwardly through the first mixture, bitumen enriched solvent contained in the first mixture can be displaced downwardly through the column.

Upon addition into the column in an up flow mode, the solvent flows upwardly through the height of the column via small void spaces in the first mixture. The solvent can flow upwardly through the continuous pumping of solvent into the column from the bottom end of the column. As the solvent flows upwardly through the first mixture, bitumen in the first mixture may be dissolved and bitumen-enriched solvent contained in the first mixture may be displaced upwardly. After the solvent has been added to the column in an up flow mode, the dissolved bitumen and solvent can flow downwardly back through the column as described above in the down flow mode. The force acting on the dissolved bitumen and solvent can either be gravity or an external force, such as a gas overpressure.

The bitumen-enriched solvent that has flowed downwardly through the height of the vertical column in either mode can exit the bottom end of the vertical column, where it can be collected. Any method of collecting the bitumen-enriched solvent can be used, such as by providing a collection vessel at the bottom end of the vertical column. The bottom end of the vertical column can 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 can be carried out for any suitable period of time. In some embodiments, collection is carried out for 2 to 30 minutes.

Bitumen-enriched solvent that has exited the column can be recycled back into the top or bottom of the vertical column or upstream of the column to perform further dissolution of any undissolved bitumen still contained in the vertical column. The collection and reintroduction of the bitumen-enriched solvent into the column can be performed several times in an attempt to increase the amount of bitumen removed from the column. Alternatively, or in conjunction with adding bitumen-enriched solvent into the column, further amounts of fresh solvent can be added to the column to displace bitumen-enriched solvent.

With respect to step 120, water is added into the column in the same manner as described above with respect to the addition of the solvent into the column. The addition of water serves to displace the solvent from the vertical column. Mixtures of water and solvent can be collected and reintroduced into the column to displace further solvent from the column. Alternatively or in conjunction with adding the water and solvent mixture back into the column, additional water can be added to the column to displace further solvent from the column.

Step 120 can be carried out in two steps, with one step occurring after the solvent-wet tailings have been discharged from the column. In a first step, the solvent-wet tailings are discharged from the column and a first portion of the quantity of water is added to the solvent-wet tailings to separate a liquid component from the solvent wet tailings. In a second step, the solvent-wet tailings are re-loaded into the column and the second portion of the first quantity of water is added to the solvent-wet tailings loaded in the column. In some embodiments, 25% to 50% of the water is used in the first portion and 50% to 75% of the water is used in the second portion.

The material contained in the vertical column after the removal of solvent generally includes solvent-dry stackable tails as described in greater detail above. The solvent-dry, stackable tails can be removed from the vertical column by any suitable process. The solvent-dry, stackable tailings can 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 is covered with one or more removable plugs or valves, and the one or more plugs or valves can be removed to allow the solvent-dry, stackable tailings 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 can be removed to allow the solvent-dry, stackable tailings to flow out of the vertical column. Alternatively, the screen may be an annular ring at the lower part of the column to allow dissolved bitumen or liquids to pass without obstructing the outflow of solids once the plug or valve is removed. In certain embodiments, the vertical column is lifted off of the ground, thereby allowing the solvent-dry, stackable tailings to flow out of the bottom end of the vertical column. External forces can also be applied to the vertical column to promote the discharging of the solvent-dry, stackable tailings from the vertical column.

In some embodiments, the solvent and/or water added into the column can be added into the column from the bottom of the column to create an upflow of solvent or water into the column. Solvent or water can be added in this manner to unplug a vertical column that has become plugged. The bottom of the column may be closed off to force the solvent or water upwards when introduced at the bottom of the column. For example, increasing the flow rate and pressure of the injected solvent or water can result in closing off the bottom of the column. The upwardly moving solvent or water can then displace or dissolve the material causing the plug in the column.

With reference to FIG. 2, a system 200 for carrying out the above-described method includes a mixer 205 for mixing bitumen material 210 and solvent 215. Any suitable mixing vessel can be used, including a mixing vessel that operates under pressure in order to maintain the solvent 215 as a liquid. A first mixture 220 is formed by the mixing of the bitumen material 210 and the solvent 215 in the mixer 205. The first mixture 220 is transported to a first separation unit 225 where bitumen-enriched solvent 230 is separated from the first mixture 220. Any separation unit suitable for separating the bitumen-enriched solvent 230 from the first mixture 220 can be used. Gas 285-1 can be pumped into the first separation unit 225 to promote separation of bitumen from the non-bitumen components of the bitumen material. When gas 285-1 is pumped into first separation unit 225, the spent gas may also exit the first separation unit 225 with the bitumen-enriched solvent 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 bitumen-enriched solvent 230 and does not require any additional separation processing (but may be recovered and reused from an economics standpoint). Removal of the bitumen-enriched solvent 230 from the first mixture 220 via first separation unit 225 results in the first mixture 220 becoming solvent-wet tailings 235. The solvent-wet tailings 235 produced by the first separation unit 225 are transported to a second separation unit 260 where the solvent 265 is removed from the solvent-wet tailings 235 by adding water 270 to the solvent-wet tailings 235. Any separation unit suitable for separating the solvent 265 from the solvent wet tailings 235 may be used. Separation of the solvent 265 from the solvent-wet tailings 235 results in the solvent-wet tailings 235 becoming solvent-dry, stackable tailings 275.

With reference to FIG. 3, a system 300 for carrying out the extraction method disclosed herein that utilizes a vertical column includes a mixing vessel 305 for mixing bitumen material 310 with a first quantity of solvent 315 to form a first mixture 320. Any type of mixing vessel may be used to mix the bitumen material 310 and the solvent 315.

The first mixture 320 is then loaded in the vertical column 325. FIG. 3 depicts the first mixture 320 being loaded in the top end of the vertical column 325, but the first mixture 320 can also be loaded from the bottom end of the vertical column 325 or from the side of the vertical column 325. Once the first mixture 320 is loaded in the vertical column 325, a second quantity of solvent or solvent vapor 330 is injected into the top end of the vertical column. The second quantity of solvent 330 flows down the height of the vertical column 325, dissolving solid bitumen in the first mixture 320 and/or displacing dissolved bitumen in the first mixture 320 along the way. The non-bitumen components of the bitumen material remain in a packed condition in the vertical column 325 as the second quantity of solvent 330 passes through the first mixture 320. The second quantity of solvent 330 exits the bottom end of the vertical column 325 as a bitumen-enriched solvent phase 335. The second quantity of solvent 330 is now a bitumen-enriched solvent phase 335 because the second quantity of solvent 330 dissolves solid bitumen contained in the first mixture 320 and/or coalesces with dissolved bitumen contained in the first mixture 320 as the second quantity of solvent 330 passed through the vertical column 325.

The bitumen-enriched solvent phase 335 is collected at the bottom end of the vertical column 325 for further processing of the bitumen contained therein. Some of the second quantity of solvent 330 remains in the first mixture 320 loaded in the vertical column 325. Water 350 is added to the vertical column 325 to displace solvent out of the vertical column 325. The water 350 flows down the height of the vertical column 325, displacing solvent contained in the first mixture 320. The water 350 exits the bottom end of the vertical column 325 as a water and solvent mixture 355, which can be separated into water and solvent so each component may be reused.

Optionally, the system also includes one or more gas purge injections 365-1 and 365-3. The gas purge injections 365-1 and 365-3 may occur before and/or after any of the solvent or water injection steps, and may serve to help separate bitumen and first solvent from the non-bitumen component of the first mixture 320.

After displacement of solvent, the material loaded in the column 325 is solvent-dry, stackable tailings 360. The solvent-dry, stackable tailings 360 is discharged out of the vertical column 325. FIG. 3 depicts solvent-dry, stackable tailings 360 being removed from the bottom end of the vertical column 325, but the solvent-dry, stackable tailings 360 may also be discharged from the top end of the vertical column 325.

With reference to FIG. 4, a system for carrying out the extraction method disclosed herein that utilizes countercurrent washing includes loading a first mixture 410 of bitumen material and solvent in a washing unit 405. The washing unit 405 receives the first mixture 410 and transports it in a first direction while moving solvent 415 towards the first mixture 410 in a direction opposite the direction the first mixture 410 is traveling. The first mixture 410 mixes with the solvent 415, during which bitumen-enriched solvent in the first mixture 410 is displaced from the first mixture 410 by the solvent or solvent vapor 415. Bitumen-enriched solvent 420 and solvent-wet tailings 425 separate due to the countercurrent configuration of the washing unit 405.

Solvent-wet tailings 425 are transported to a second washing unit 450 where it flows in a direction opposite to a direction of flow of water 455 introduced into the second washing unit 450. The solvent-wet tailings 425 mix with the water 455, during which the solvent in the solvent-wet tailings 425 is displaced by the water 455. Accordingly, solvent-water mixture 460 and solvent-dry, stackable tailings 465 are formed. The solvent-water mixture 460 and the solvent-dry, stackable tailings 465 separate due to the countercurrent configuration of the secondwashing unit 450. The final stage 450 may be a column, vessel, or plate and frame filter as described previously to effect a more efficient final water removal to produce solvent-dry stackable tailings.

In any of the embodiments described herein, the method can include a further step of depositing the solvent-dry, stackable tailings in a mine pit formed when mining the first bitumen material. 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 is 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 bitumen material is less than the original amount of bitumen material 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 bitumen material generally produce wet tailings having a volume that is 125% of the original volume of the mined bitumen material, 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 can lead to a much earlier trafficable reclamation for the deposit, an aspect of tailings management which has not been attained by oil sands operators to date.

As described in greater detail in U.S. Pat. Nos. 7,985,333 and 7,909,989, further processing can be performed on other components produced by the methods described above. For example, the bitumen-enriched solvent phase can be processed to separate the bitumen therefrom. Furthermore, as described U.S. Published Patent Application No. 2011/0017642, 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 can be cracked in a nozzle reactor (with or without deasphalting) to produce light hydrocarbon distillate. The light hydrocarbon distillate can then be used as a solvent to extract bitumen from bitumen material. In one example, the light hydrocarbon distillate produced is recycled within the same process to initiate extraction of bitumen from further bitumen material. Additionally, any solvent separated or removed from a mixture can be recovered and reused in the process.

Paraffinic solvent can be present in the tailings as a result of using paraffinic solvent to dissolve and extract bitumen from the bituminous material. Water effectively removes paraffinic solvent from the tailings at least in part because of the immiscibility of the water and paraffinic solvent. For example, when tailings are treated with water by passing a plug of water through the tailings, the immiscibility of the water and paraffinic solvent helps to ensure that the water pushes the paraffinic solvent out of the tailings rather than mix with the paraffinic solvent and potentially leave a mixture of paraffinic solvent and water in the tailings.

In some embodiments, a method of performing bitumen extraction on bituminous material that includes the formation of solvent-dry tailings includes a step 500 of passing a solvent through a first quantity of bituminous material, and a step of 510 of passing water through the first quantity of bituminous material. In this method, the solvent is a paraffinic solvent.

In step 500, solvent is passed through a first quantity of bituminous material. One aim of step 500 is to dissolve bitumen contained in the bituminous material into the solvent as a means for eventually extracting the bitumen content from the bituminous material. The solvent typically passes through the bituminous material by traveling through the interstitial spaces within the bituminous material. As it passes through these spaces, the solvent contacts bitumen contained in the bituminous material and dissolves the bitumen. The solvent thus becomes “bitumen-enriched,” and when the bitumen-enriched solvent has passed all the way through the bituminous material, bitumen content in the bituminous material has been effectively extracted from the bituminous material.

The bituminous material can be similar or identical to the bitumen material described in greater detail above. In some embodiments, the bituminous material is oil sand or oil sand. In some embodiments, the bituminous material is obtained from previous bitumen extraction process steps. For example, in some embodiments, oil sand or the like is mixed with solvent capable of dissolving bitumen and the resulting mixture is separated into a bitumen-enriched solvent phase and a bitumen-depleted tailings phase. The mixing can be carried out in a mixing drum or the like, and the separation can be carried out using a thickener, hydrocyclone, or the like. The bitumen-enriched solvent phase can be subjected to further processing that separates the solvent from the bitumen. Separated solvent can be reused in the process and bitumen can be subjected to upgrading processes. The bitumen-depleted tailings phase from such a process will typically include a solvent content and a bitumen content in addition to the sand and clay of the original oil sand. For example, in some embodiments, the bitumen-depleted tailings phase includes up to 40% of the bitumen contained in the original oil sand. This bitumen-depleted tailings can serve as the bituminous material used in the method described herein.

Any technique that results in the passing of solvent through the bituminous material can be used. In some embodiments, the solvent is passed through the bituminous material by loading the bituminous material in a vessel, adding solvent at one end of the vessel, and causing the solvent to move through the bituminous material to the opposite end of the vessel. Any vessel capable of containing the bituminous material can be used, and the size and shape of the vessel is not limited. Solvent can be moved through the bituminous material using, for example, gravity or an external force, such as the application of an inert gas at one end of the vessel. When inert gas is used to move solvent through the bituminous material, the vessel can be a sealed vessel, so that the introduction of inert gas into one end of the vessel forces the solvent to move through the bituminous material to the other end of the vessel.

In some embodiments, the vessel or sealed vessel is a vertical column as described in greater detail above. The bituminous material is loaded in the vertical column as described above, and solvent is added to the top end of the vessel such that it may move downwardly through the bituminous material loaded in the vertical column to the bottom end of the vessel. As mentioned above, gravity can be relied on to move the solvent down through the bituminous material, or the vertical column can be a sealed vertical column and inert gas can be introduced at the top end of the vertical column after solvent has been added into the column to force the solvent to move downwardly through the bituminous material loaded in the vertical column. When inert gas is used to promote the movement of the solvent through the bituminous material, the inert gas can be applied at a pressure ranging from 30 psig to 300 psig. Typically, the pressure at which the inert gas is applied into vertical column can vary based on how packed the bituminous material is in the vertical column, the height of the column, and the resulting pressure drop over the column length. The more packed the bituminous material, the greater the pressure will need to be to move the solvent downwardly through the bituminous material. Any suitable inert gas can be used, and in some embodiments, the inert gas is nitrogen.

The solvent used in step 500 can be similar or identical to the first solvent described in greater detail above. In some embodiments, the first solvent is a solvent capable of dissolving bitumen. In some preferred embodiments, the solvent is a paraffinic solvent.

The amount of solvent passed through the bituminous material in step 500 typically depends on the bitumen content of the bituminous material, although other factors can impact how much solvent is passed through the bituminous material. In some embodiments, a ratio of solvent to bitumen content of the bituminous material on a volume basis (or S:B ratio) is used to specify the amount of solvent passed through the bituminous material. The S:B ratio in step 500 can vary from between 0.5:1 to 4:1.

The solvent that passes through the bituminous material will have a bitumen content based on the amount of bitumen that dissolves into the solvent as it passes through the bituminous material. In some embodiments, the solvent will have removed from 40% to 75% of the bitumen content of the bituminous material. The solvent that passes through the bituminous material can therefore be collected and subjected to further processing that separates the solvent from the bitumen content. The separated solvent can be reused in the process, and the bitumen can be subjected to upgrading processes to produce lighter hydrocarbons.

In some embodiments, a portion of the solvent that is introduced into the bituminous material will not pass all the way through the bituminous material, and will instead remain in the interstitial pores of the bituminous material. This trapped solvent can still have dissolved bitumen therein, and therefore a step 510 of passing water through the bituminous material can be carried out to remove solvent from the bituminous material. When the solvent is paraffinic, the water is effective at displacing the solvent from the bituminous material due to the immiscibility of the paraffinic solvent and the water. For example, when a plug of water is moved through the bituminous material, the paraffinic solvent is pushed out of the bituminous material by the water plug rather than mixing with the water, which could possibly lead to paraffinic solvent remaining in the bituminous material.

Passing water through the bituminous material can be carried out in a similar or identical fashion to how the solvent is passed through the bituminous material. While any manner of passing the water through the bituminous material can be used, some embodiments call for the water to be passed through bituminous material loaded in a vessel, such as a sealed vertical column. In such embodiments, water is introduced at the top end of the sealed vertical column, and moves downwardly through the bituminous material under the force of gravity or through the application of external force. In some embodiments, inert gas is introduced into the top end of the sealed vertical column after water has been introduced into the top end of the sealed vertical column to push the water downward through the bituminous material. When inert gas is introduced, the inert gas can be introduced at a pressure of from 30 to 50 psig. In some embodiments, the pressure of the inert gas is kept relatively low so as not to move the water through the bituminous material at a velocity that results in disrupting the clays attached to the sand particles in the bituminous material.

The amount of water used in step 510 can be based on a ratio of volume of water added to the total volume of the interstitial pore spaces in the bituminous material (W:P ratio). In some embodiments, the W:P ratio for step 510 is from 1:1 to 5:1, meaning that, generally speaking, a volume of water anywhere from one to five times the volume of pore spaces in the bituminous material is passed through the bituminous material.

The water passing through the bituminous material in step 510 will result in solvent and water exiting the bituminous material. The solvent can include dissolved bitumen, and therefore steps can be taken to separate the water, solvent, and bitumen. The water and solvent (having bitumen dissolved therein) can be relatively easy to separate due to the immiscibility of the solvent in the water. In some embodiments, the solvent and water may naturally phase separate, forming a layer of solvent over the water. Once the solvent and water are separated, the solvent can be processed to separate the solvent from the bitumen. Separated water and solvent can be reused in the process, and bitumen can be subjected to upgrading processing.

Any of the above described steps wherein solvent or water is passed through the bituminous material can be performed in multiple stages. That is to say, multiple quantities of solvent can be passed through the bituminous material in individual stages prior to passing any water through the bituminous material. Multiple quantities of water can be passed through the bituminous material in individual stages after the solvent wash has been completed. Using multiple stages of washes for one or more of the solvent and water can result in more complete removal of bitumen and solvent from the bituminous material.

After steps 500 and 510 have been carried out, a tailings phase is left over. When a vessel is used to carry out these steps, the tailings can be discharged from the vessel. The tailings phase generally includes the non-bitumen solid materials of the original bituminous material, such as sand and clay. In conventional bitumen extraction processes that utilize solvents, the tailings include a solvent content. However, in the above method, the water wash can result in the production of tailings that have less than 200 ppm solvent. Additionally, the tailings can include less than 2 wt % of the original bitumen content of the bituminous material. Bitumen and solvent levels in these ranges can satisfy stringent environmental regulations set by various organizations overseeing oil sand mining and bitumen extraction.

The tailings can also include a water content due to the water content present in the original bituminous material and the water added to the bituminous material as part of removing solvent from the bituminous material. In some embodiments, the water content of the tailings is about 14 wt % and the tailings can be transported by conveyor for deposition. In some embodiments, it may be useful to add additional water to the discharged tailings so that the tailings are in the form of a pumpable slurry.

In some embodiments, a method of extracting bitumen from bituminous material and producing solvent-dry tailings includes a step 600 of contacting a bituminous material with a solvent and forming a solvent-wet bituminous material and a step 610 of contacting the solvent-wet bituminous material with water and forming a water-wet bituminous material. In the method described above, the solvent is preferably a paraffinic solvent.

The first solvent, water, and bituminous material used in steps 600 and 610 are similar or identical to the first solvent, second solvent, and water described above in the method including steps 500 and 510.

Each or both of the contacting steps 600 and 610 can include passing the solvent and water through the bituminous material as described in greater detail above. When a contacting step 600 or 610 includes passing one of the wash materials through the bituminous material, the bituminous material becomes wet with whichever of the wash materials is passed through the bituminous material. For example, when bituminous material is contacted with solvent by passing the solvent through the bituminous material, a portion of the solvent becomes trapped in the bituminous material, thereby making the bituminous material solvent-wet bituminous material. When steps 600 and 610 include passing the wash material through the bituminous material, the method is similar or identical to the method described above (i.e., the method including steps 500 and 510).

Each or both of the contacting step 600 and 610 can also include adding wash material to bituminous material and mixing the two components into a mixture or slurry. Mixing can differ from passing a wash material through the bituminous material in that a mixing step does not require the movement of wash material from one side of the bituminous material through to the opposite side of the bituminous material and the discharge of a relatively large portion of the wash material from the bituminous material. Rather, mixing generally includes a majority or all of the wash material remaining with the bituminous material in the form of a slurry and the two components being mixed together.

Any suitable manner of mixing solvent or water with the bituminous material can be used to carry out step 600 or 610. The mixing can occur by adding both the bituminous material and the wash material to a vessel and mixing the two components together to form a slurry of bituminous material that is wet with the specific wash material used in the contacting step. Mixing together the wash material and the bituminous material can provide desirable results. For example, when solvent is mixed with bituminous material, the mixing promotes the dissolution of bitumen from the bituminous material into the solvent.

In embodiments where any of the contacting steps 600 or 610 include mixing wash material with the bituminous material, the contacting step can further include a step of separating out certain components from the resulting mixture. When step 600 includes mixing, the separation step will generally include separating a bitumen-enriched solvent phase from solvent-wet bituminous material. When step 610 includes mixing, the separation step will generally include separating a mixture of solvent and water from the solvent-wet bituminous material. Any suitable separation methods can be used to carry out the above-described separations. Exemplary separation methods can include any of those described in previous embodiments, including but not limited to, filtering, settling and decanting, gravity or gas overpressure drainage, and displacement washing.

In some embodiments, one or both of the separation steps described above are carried out in a hydrocyclone. Generally speaking, the mixture formed in step 600 or 610 is transported into a hydrocyclone where the hydrocyclone acts to separate the mixture into an overflow and an underflow. When the mixture formed in step 600 is separated in a hydrocyclone, the mixture will be separated into a bitumen-enriched solvent overflow and a solvent-wet bituminous material underflow. When the mixture formed in step 610 is separated in a hydrocyclone, the mixture will be separated into a solvent and water mixture overflow and a water-wet bituminous material underflow.

Any suitable hydrocyclone can be used to carry out the separation process. Typical hydrocyclones suitable for use in the above described method include hydrocyclone separators that utilize centrifugal forces to separate materials of different density, size, and/or shape. The hydrocyclone will typically include a stationary vessel having an upper cylindrical section narrowing to form a conical base. The mixtures are introduced into the hydrocyclone at a direction generally perpendicular to the axis of the hydrocyclone. This induces a spiral rotation on the mixture inside the hydrocyclone and enhances the radial acceleration on the solids within the mixture. The hydrocyclone also typically includes two outlets. The underflow outlet is situated at the apex of the cone, and the overflow outlet is an axial tube rising to the vessel top (sometimes also called the vortex finder).

When the density of the solids is greater than that of the fluid portion of the mixture, the heavier solid particles migrate quickly towards the cone wall where the flow is directed downwards. Lower density solid particles migrate more slowly and therefore may be captured in the upward spiral flow and exit from vortex finder via the low pressure center. Factors affecting the separation efficiency include fluid velocity, density, and viscosity, as well as the mass, size, and density of the tailings particles. The geometric configuration of the hydrocyclone can also play a role in separation efficiency. Parameters that can be varied to adjust separation efficiency include cyclone diameter, inlet width and height, overflow diameter, position of the vortex finder, height of the cylindrical chamber, total height of the hydrocyclone, and underflow diameter.

A separate hydrocyclone can be provided to carry out each of the separation steps that occur after the contacting (i.e., mixing) steps 600 or 610, or a single hydrocyclone can be used for one or more separations. In embodiments where a separate hydrocyclone is provided for each separation, a first hydrocyclone receives and separates the first mixture formed in step 600, and a second hydrocyclone receives and separates the second mixture formed in step 610. Each of the hydrocyclones can be sized and configured especially for the separation for which it is used.

When each separation step is carried out in a separate hydrocyclone, the process can generally proceed as follows: A bituminous material and a solvent are contacted so as to form a first mixture. The first mixture is delivered into the first hydrocyclone and separated into a bitumen-enriched solvent overflow and a solvent-wet bituminous material underflow. The underflow is contacted with water so as to form a second mixture. The second mixture is delivered into the second hydrocyclone and separated into a solvent and water overflow and a water-wet bituminous material underflow.

In some embodiments, each separation step can include multiple stages such that the mixture is passed through the hydrocyclone multiple times before being passed through to the next hydrocyclone. For example, the first mixture of bituminous material and solvent can be passed through a hydrocyclone a first time, followed by collecting the first solvent-wet bituminous material overflow, adding an additional quantity of solvent, and passing the resulting mixture through the same hydrocyclone. This can be repeated numerous times to increase the separation efficiency. In the case of the second separation step, multiple passes through the hydrocyclone may be necessary to effect a suitable separation of solvent from the water-wet bituminous material because of the immiscibility between the solvent (i.e., paraffinic solvent) and the water.

When solvent is added to a stream separated by the hydrocyclone, such as in the case of adding additional solvent to the solvent-wet bituminous material overflow described above, the additional solvent can be obtained from a downstream hydrocyclone separation. In this manner, the solvent flows countercurrent to the solids for multiple washes and more efficient bitumen extraction with higher bitumen loading into the solvent is obtained with each subsequent hydro cyclone stage.

Any bitumen recovered from the above-described methods, such as the bitumen content of the bitumen-enriched solvent phases, can also undergo any type of upgrading processing known to those of ordinary skill in the art. Upgrading of the bitumen can 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 can 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 can also include any processes known to those of ordinary skill in the art, such as distillation, hydrocracking, hydrotreating, and coking. The 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.

Several advantages can be realized by using the methods and systems described herein. Specifically, the use of a single solvent where the solvent is paraffinic can provide numerous advantages over other solvent bitumen extraction techniques, including those techniques using more than one type of solvent. Firstly, the use of paraffinic solvent can increase the throughput of the method by a factor of 2 or greater. Improved throughput can be realized due to the use of the lighter paraffinic solvent that is capable of solvating the bitumen material faster than heavier solvents and results in reduced viscosity dilbit, which can be recovered from the solids easier. The paraffinic solvent can also advantageously precipitate asphaltenes, further eliminating the heavy viscosity component. In some instances, the paraffinic solvent causes the asphaltenes to precipitate into the solids, and more specifically onto the finer clays. The precipitated asphaltenes are captured by finer clays while the dilbit passes through and out of the bitumen material for successful bitumen extraction. The precipitation of asphaltene can also be beneficial by allowing for the upgrading of bitumen extracted in the dilbit using conventional upgrading processing equipment (i.e., specialized upgrading equipment capable of handling asphaltenes as well as bitumen is not required).

The systems and methods that use a single solvent instead of two different types of solvents can also be advantageous from a capital expenditure (CAPEX) perspective. Single solvent systems typically only require a single distillation unit for the separation and recovery of the single solvent. Single solvent systems, including single solvent systems using a paraffinic solvent, also tend to require smaller distillation units as compared to when heavier solvents are used. Operating expenditures (OPEX) are also reduced when using a single solvent system versus a two solvent system. For example, lower heating duty is required for removing a single, relatively light, solvent from the tailings. Finally, environmental advantages can result from the single solvent system. Carbon dioxide emissions and fugitive solvent loses can be reduced when a single solvent system is used in lieu of a system that uses two different types of solvents.

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.