Methods and apparatus for bitumen extraction   

Abstract: A bitumen extraction method can include the use of a two or more mixing drums aligned in series for spraying solvent over bituminous material and/or tailings loaded in the mixing drums while the mixing drums rotate. Such mixing can result in the dissolution of bitumen into the solvent, which then allows for the separation of a “dilbit” stream from the bituminous material.

This application claims priority to U.S. Provisional Patent Application No. 61/511,894, filed Jul. 26, 2011, and U.S. Provisional Patent Application No. 61/525,557, filed Aug. 19, 2011. Each application is incorporated herein by reference in its entirety.

Bituminous material such as oil sands typically include sand, clay, water, and heavy crude oil. Many countries in the world have large deposits of oil sands, including the United States, Russia, and various countries in the Middle East. However, three quarters of the world\'s reserves are found in Venezuela and Canada. Oil sands may represent as much as two thirds of the world\'s total petroleum resource, but are difficult to develop because of the expense associated with recovering oil from oil sands.

Bitumen extraction from bituminous material such as oil sand can be a very energy intensive process. In the extraction of bitumen from bituminous material, the bituminous material is typically mined, usually by a bucket wheel excavator of dragline, and is then subjected to hot water extraction processing. In a typical hot water extraction process, the bituminous material is mixed with hot water such that the bitumen content of the bituminous material floats as a froth and the solid matter content of the bituminous material sinks, thereby making it possible to skim off the froth for further separation and eventual refinement to finished products. In some conventional hot water extraction processes, 87% by weight of bitumen and diluent naphtha are recovered from the bituminous material, with a loss of 13% by weight being dumped with the waste solid matter. The disposal of the solid matter involves passing the solid matter together with accompanying hot water to a tailings pond. The hot water that is lost can be at a temperature of approximately 185° F. to 195° F. The loss of this hot water considerably reduces the overall plant thermodynamic efficiency as the beat loss must be made up when reheating cold water for the hot water extraction process.

In many hot water bitumen extraction processes, the tailings produced by the process include solid matter, hot water, and hydrocarbons not removed by the hot water process. These tailings can be sluiced into retaining areas, such as large ponds formed from dams or dykes built from tailings. When a first pond is filled, a second dam is built in the middle of the mined out area and this process of building dams and filling the ponds formed between the dams is continued until the reserve of mineable oil sands has been depleted. At this future time, most of the area of the mined out acreage will be covered under almost a continuous pond including water, oil emulsions, and clay fines gel. Environmental authorities have determined that there has been and will continue to be pollution impacts on the underground water streams, surrounding lakes, and other fresh water bodies adjacent to the mining areas. Under this tailings disposal system, little, if any, of the mined out land can be reclaimed and put to useable form.

SUMMARY

Disclosed below are representative embodiments that are not intended to be limiting in any way. Instead, the present disclosure is directed toward novel and nonobvious features, aspects, and equivalents of the embodiments of the methods described below. The disclosed features and aspects of the embodiments can be used alone or in various novel and nonobvious combinations and sub-combinations with one another.

In some embodiments, a bitumen extraction method includes a step of feeding a first quantity of bituminous material into a first mixing drum, a step of spraying first solvent over the first quantity of bituminous material inside the first mixing drum, a step of separating the first quantity of bituminous material into a first dilbit stream and a first tailings stream, a step of feeding the first tailings stream into a second mixing drum, a step of spraying first solvent over the first tailings stream inside the second mixing drum, and a step of separating the first tailings stream into a second dilbit stream and a second tailings stream.

In some embodiments, a bitumen extraction system includes a first mixing drum having a first solvent inlet, a first dilbit outlet, and a first tailings outlet; a first separation unit having a second dilbit inlet in fluid communication with the first dilbit outlet, a cleaned dilbit outlet, and a solid materials outlet; and a second mixing drum having a first tailings inlet in fluid communication with the first tailings outlet, a second dilbit outlet in fluid communication with the first solvent inlet, and a second tailings outlet.

In at least one or more embodiments, novel features and/or advantages of the method can include use of a mixing drum to add solvent to bituminous material, recover dilbit, and remove tailings; use of multiple mixing drums in counterflow configuration; use of one or more hydrocyclones to carry out bitumen extraction; reducing or eliminating the need for hot water in bitumen extraction processing; reducing or eliminating tailings ponds containing oil emulsions and unstable clay fine gels; improving the thermodynamic efficiency of the bitumen extraction process; and improving the bitumen recovery efficiency to greater than 90%.

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 extracting bitumen from bituminous material as disclosed herein;

FIG. 2 is a process flow diagram detailing a method for extracting bitumen from bituminous material as disclosed herein;

FIG. 3 is a flow chart detailing a method for extracting bitumen from bituminous material as disclosed herein;

FIG. 4 is a process flow diagram detailing a method for extracting bitumen from bituminous material as disclosed herein;

FIG. 5 is a process flow diagram detailing a method for extracting bitumen from bituminous material as disclosed herein;

FIG. 6 is a process flow diagram detailing a method for extracting bitumen from bituminous material as disclosed herein;

FIG. 7 is a process flow diagram detailing a method for extracting bitumen from bituminous material as disclosed herein;

FIG. 8 is a flow chart detailing a method for extracting bitumen from bituminous material as disclosed herein; and

FIG. 9 is a process flow diagram detailing a method for extracting bitumen from bituminous material as disclosed herein.

DETAILED DESCRIPTION

With reference to FIG. 1, a bitumen extraction method according to some embodiments disclosed herein includes a step 100 of feeding bituminous material into a mixing drum, a step 110 of spraying solvent over the bituminous material inside the mixing drum, and a step 120 of separating the bituminous material into a dilbit stream and a tailings stream.

The mixing drum used in step 100 can generally include any type of drum suitable for use in mixing together bituminous material and solvent. In some embodiments, the mixing drum is an enclosed drum that includes one or more inlets for feeding bituminous material and solvent into the drum and one or more outlets for removing various mixtures of materials from the mixing drum. The various inlets and outlets in the mixing drum can be located throughout the mixing drum. The material of the mixing drum is not limited, and may include materials that are generally impermeable and corrosion resistant. In some embodiments, the mixing drum has a generally cylindrical shape, although other shapes may be used. The mixing drum can also vary in size and dimensions, and the size and dimensions of the drum are generally selected based on the amount of bituminous material to be handled inside the mixing drum and the bituminous material characteristics (i.e. particle size, dissolution rate etc.).

In some embodiments, the mixing drum is a cylindrically-shaped drum oriented such that the axis of the cylindrically-shaped drum is generally horizontal. The cylindrically-shaped drum can also be slanted such that one end is higher than the other, or positioned in a generally vertical position. However for purposes of this discussion, the drum will be described in the scenario where the axis of the drum is generally horizontal.

The cylindrical drum can include one or more inlets located at various locations throughout the drum for feeding bituminous material inside of the drum. In some embodiments, the inlets are located proximate one end of the drum for the introduction of bituminous material into the drum. The inlets can be located around the circumference of the drum near one end of the drum, in the end wall of the drum (i.e., the wall perpendicular to the ground when the axis of the drum is positioned horizontally), or a combination of both.

The drum can also include inlets for providing solvent to the interior of the drum. The inlets for adding solvent into the drum can be located anywhere about the drum, such as those locations described above with respect to inlets for feeding bituminous material inside of the drum. In some embodiments, inlets are provided at various locations throughout the drum such that solvent can be added into the drum at various locations throughout the drum.

In some embodiments, the various inlets and outlets included in the mixing drum can be sealed when mixing occurs within the mixing drum. Sealing of the inlets and outlet can help to ensure that materials inside the mixing drum do not leak out of the mixing drum, and also that any gases or vapors produced inside of the mixing drum do not leak out of the mixing drum.

In some embodiments, one or more spray bars are positioned within the drum to provide solvent to the interior of the drum. In such embodiments, the spray bar passes through an end wall of the drum and solvent enters the interior of the drum by passing through the spray bar and into the drum. The spray bar can include numerous nozzles along its length where solvent is sprayed into the interior of the drum. In some embodiments, the spray bar is oriented generally parallel to the axis of the cylindrical drum, although other orientations can be used.

In some embodiments, the interior walls of the mixing drum include a liner that protects the shell of the mixing drum. This liner can cover the entirety of the interior wall of the mixing drum or only portions of the interior of the mixing drum. Any suitable liner material can be used, and in some embodiments, the liner material is alloy steel or a thick layer of rubber or any other elastomer that is compatible with the selected solvent. This liner material prevents wear to the mixing drum. Any manner of securing the liner to the interior walls of the mixing drum can be used, and in some embodiments, the liners are bolted securely to the mixing drums with specially designed washers that prevent drum leakage.

The cylindrical drum can also include a mechanism for rotating the drum, including rotating the drum about its axis. Any manner of rotating the drum can be used, including hydraulic motors and tire and trunnion mechanisms. The speed at which the drum can be rotated can vary over a wide range of speeds.

The cylindrical drum can also include a screen liner for facilitating the separation of materials inside the drum. The screen liner can have any suitable shape, including a generally cylindrical shape. When the screen liner has a cylindrical shape, the diameter of the screen liner can be smaller than the diameter of the mixing drum such that the screen liner is positioned inside of and coaxial with. the mixing drum. In some embodiments, the screen liner can include a plurality of coaxially aligned screens, with each screen having a different mesh size. In this manner, the multiple screen liner can effect a coarse and fine separation of materials inside the mixing drum.

The screen liner can extend along the entire length of the drum or only a portion of the length of the drum. In some embodiments, the screen liner is located at only one end of the drum, and preferably the end of the drum opposite inlets for introducing bituminous material into the drum. In some embodiments, the screen liner has a length that is more than half the length of the mixing drum. For example, the mixing drum can have an overall length of 22 meters, with the screen liner having a length of 12 meters. In such a configuration, mixing occurs in the mixing drum along the first 10 meters of the mixing drum, and separation occurs along the last 12 meters of the mixing drum. In this manner, mixing between bituminous material and solvent can take place along a first portion of the length of the drum while separation occurs at the end of the drum, after substantial mixing has taken place.

The mesh size of the screen liner can vary and be adjusted depending on the sizes of the material to be separated. In application, the screen effectively creates an area between the liner and the drum where material that passes through the liner can collect and be removed from the drum via a first outlet, and an area within the screen liner where bituminous material having bitumen extracted therefrom (i.e., tailings) remains. The material that cannot pass through the liner remains within this inner area can be removed from the drum via a second (i.e., tailings) outlet. The first outlet is therefore positioned along the drum in a position that communicates with the area between the liner and the drum. In some embodiments, this location will be along the circumference of the drum. Similarly, the second outlet can be positioned at a location that is in communication with the interior of the screen liner. In some embodiments, this location will be on an end wall of the drum. In some embodiments, the mesh size of the screen liner is from between 40 mesh and 200 mesh. The cylindrical drum can further include lifting shelves (i.e., lifters) that help to promote mixing within the drum when the drum rotates. The height of each lifting shelf generally extends radially inward from the interior wall of the mixing drum, while the length of each lifting shelf is generally oriented parallel to the axis of the drum. In this manner, the lifting shelves carry a portion of the material inside of the drum up along the wall of the drum as the drum rotates. Eventually the lifting shelves rotate to a position where they slant downwardly and the lifted material falls back down towards the bottom of the drum. This movement of the material helps to promote mixing as discussed in greater detail below. The lifting shelves can be made from any suitable material, including steel, rubber, or other elastomers compatible with the solvents in use. Each lifting shelf can have a length that extends the entire length of the drum or the lifting shelves can lengths that are shorter than the length of the drum. When in shorter segments, various lifting shelves along the length of the drum can be offset from other lifting shelves located at other positions along the length of the drum.

The height of each lifting shelf can be any suitable height and the heights of the lifting shelves can be the same or varying throughout the drum. In some embodiments, the placement and height of each lifting shelf can be adjusted in order to vary the residence time of the material inside of the drum. Longer residence times can lead to more nixing, and therefore adjustments can be made to the placement and height of the lifting shelves used in order to increase or decrease residence time. In some embodiments, the lifting shelves can be in the form a flute, such as commonly used in a cement mixer, to gently knead and mix the slurry without creating high shear.

Retention rings may also be included within the drum to further vary residence time. One or more retention rings can be placed axially along the length of the drum and will slow the movement of material from one end of the drum to the other, thereby increasing residence time and promoting further mixing between materials.

In some embodiments, the mixing drum may also include a heating mechanism for heating the material inside of the mixing drum. Any suitable type of heater can be used to accomplish the heating of material inside the mixing drum. In some embodiments, the mixing drum includes direct or indirect heating via, for example, a hot water or steam jacket surrounding a portion or all of the exterior of the mixing drum to thereby provide heat from the hot water or steam passing through the jacket through the walls of the mixing drum and to the material inside of the mixing drum. Use of a heater with the mixing drum can be especially preferable when the materials inside of the mixing drum are cold when transported into the mixing drum. For example, when the bituminous material transported into the mixing drum is mined Alberta oil sands, the temperature of the bituminous material is very cold. In some embodiments, the heater used in conjunction with the mixing drum is capable of heating the materials inside of the mixing drum to a temperature between 20° C. and 75° C. The heater may be incorporated with the mixing drum to create a heated mixing drum (e.g., steam jacket) or the heater may be an independent device to raise the temperature of the bituminous material and/or solvent prior to entering the mixing drum. In some embodiments the heater may be upstream in the process flow sheet either before a primary crusher or incorporated within the primary crushing stage.

In some embodiments, the mixing drum is a trommel or a pulper. Trommels or pulpers generally include the closed drum configuration used for the mixing drum and can further include the internal screen mechanism for separating various materials inside of the drum. Any trommel or pulper suitable for use in mixing together and separating different materials can be used.

The bituminous material fed into the mixing drum can include any material that includes a bitumen content. In some embodiments, the bituminous material is oil sands or tar sands. The source of bituminous material is also not limited, and can include bituminous material obtained from natural deposits (such as by mining) or material that is produced by other processes (such as distillation bottoms produced by a distillation column). The bitumen content of the bituminous material can vary across a wide range and is generally dictated by the quality of the bituminous material being processed. For example, high quality bituminous material can include greater than 20% by weight bitumen, while lower quality bituminous material can include less than 5% by weight bitumen. Other components of the bituminous material can include, but is not limited to, water, clay, and sand.

Any suitable manner for feeding the bituminous material into the mixing drum can be used. As mentioned above, the bituminous material can be fed into the mixing drum through one or more inlets located at various locations throughout the mixing drum. The bituminous material can be transported to the mixing drum inlet by any manner, including through the use of conveyor belts, chutes, hoppers, and screw feeders. In some embodiments, the bituminous material is transported into the mixing drum as the mixing drum is rotating about its axis.

In some embodiments, the bituminous material may be broken into smaller pieces prior to introduction into the mixing drum. Any manner of breaking up the large pieces of bituminous material may be used, including the use of a traditional breaker, sizer, or crusher. In some embodiments, the bituminous material is broken up into pieces having a size of less than 3 inches or, in some cases, less than 1 inch.

In some embodiments, solvent is mixed with the bituminous material prior to and/or during the process of breaking up larger pieces of bituminous material into smaller pieces. The solvent used during the breaking/crushing step can be the same solvent used in subsequent solvent extraction steps. In some embodiments, the solvent is a paraffinic solvent, such as pentane. The solvent used in the breaking/crushing step can be heated, such as to within a range of from 50° F. to 100° F. Additionally, the apparatus used to crush the bituminous material can be heated using an internal or external heating mechanism.

Adding the solvent to the bituminous material can be carried out in any suitable manner that wets the bituminous material with solvent and begins the process of dissolving bitumen in the solvent. In some embodiments, the solvent is sprayed over the bituminous material. For example, a crushing apparatus can be configured with one or more spray nozzles for spraying solvent over the bituminous material before and/or as the bituminous material passes through the crushing mechanism (e.g., a crushing roller). In other embodiments, the solvent and the bituminous material can be mixed together to form solvent-wet bituminous material prior to being introduced into a crushing apparatus. In other words, a mixing vessel separate from the crushing apparatus can be provided that prepares the solvent-wet bituminous material prior to introducing the bituminous material into the crushing apparatus. Any suitable mixing vessel, including a mixing vessel having mixing blades, can be used. Adding solvent to the bituminous material can also be carried out on the conveyors, buckets, or chutes used to transport the bituminous material to the crushing apparatus.

Any suitable amount of solvent can be added to the bituminous material. In some embodiments, the amount of solvent added to the bituminous material is from 0.5 to 4 times the amount of bitumen in the bituminous material on a v/v basis.

The solvent-wet bituminous material is subsequently crushed in order to reduce the size of clumps of bituminous material and assist with further mixing between the solvent and the bituminous material. Any manner of crushing the solvent-wet bituminous material can be used, including the use of crushing apparatus known to those of ordinary skill in the art. Exemplary crushing mechanisms include, but are not limited to, crushing rollers or sizers.

In some embodiments, the solvent-wet bituminous material is crushed by passing the solvent-wet bituminous material through crushing rollers. The crushing rollers can be individually driven by electrical motors, gear motors, or with coupling and gears counter rotating via V-belts. Even distribution of the solvent-wet bituminous material across the entire length of the crushing rollers or other crushing mechanisms, the use of a favorable angle of entry, and in the case of crusher rollers, adjusting the speed and diameter of the crusher rollers, can help to ensure efficient crushing of the solvent-wet bituminous material and reduced wear and tear on the crushing mechanism.

Crushing rollers used to crush the solvent-wet bituminous material can also be internally heated to help improve disaggregation. Any suitable manner of internally heating the crushing rollers can used, such as through the use of steam, hot water, or electricity. The crusher rollers can be heated to any suitable temperature for improving disaggregation. In some embodiments, the crusher rollers are heated to a temperature below the boiling point temperature of the solvent, such as from 50° F. to 100° F.

In some embodiments, the crusher rollers are provided with perforations or holes that deliver solvent to the surface of the crusher rollers. Providing solvent in this manner can create a wet film on the surface of the crusher rollers that further reduced mechanical wear and tear on the surface of the crusher rollers. The solvent delivered through these holes can be heated and can be delivered to the surface of the crusher rollers continuously or intermittently.

In some embodiments, conveyors can be used to deliver bituminous material into the crushing apparatus. In instances where the bituminous material is wetted with solvent prior to being introduced into the crushing apparatus, the conveyors can be used to deliver solvent-wet bituminous material into the crushing apparatus. In instances where the mechanism for adding solvent to the bituminous material is incorporated into the crushing apparatus (e.g. spray nozzles located within the crushing apparatus and upstream of the crushing mechanism), the conveyors can be used to deliver dry bituminous material into the crushing apparatus.

In some embodiments, the steps of adding solvent to the bituminous material and crushing the solvent-wet bituminous material are repeated. Additional solvent can be added to the crushed solvent-wet bituminous material produced by the first solvent addition step and the first crushing step, followed by subjecting the crushed solvent-wet bituminous material to a second crushing step. Following the one or more wetting and crushing steps, the bituminous material can be fed into the mixing drum.

Once bituminous material has been fed into the mixing drum, a step 110 of spraying a solvent over the bituminous material inside the mixing drum takes place. The solvent wets the bituminous material and forms a slurry of material inside the mixing drum. One aim of adding solvent to the bituminous material inside of the drum is to promote the dissolution of bitumen into the solvent to thereby extract it from the bituminous material. The rotating mixing drum, lifting shelves, retention rings, heat and other mechanisms can be used to promote the mixing between the bituminous material and the solvent and the dissolution of the bitumen in the solvent. Eventually, a phase of bitumen diluted in solvent, also referred to as “dilbit,” and a phase of bitumen-depleted tailings will result from the mixing of solvent and bituminous material inside of the mixing drum.

Any solvent capable of dissolving all or a specific part of the bitumen can be sprayed over the bituminous material inside of the mixing drum. Exemplary solvent suitable for use in step 110 include paraffinic solvents (such as propane and pentane), naphtha, bio-diesel, methanol, and ethanol. In some embodiments, the solvent is “dilbit,” i.e., bitumen diluted in a solvent. Any of these solvents mentioned above may serve as the solvent component in the “dilbit.” In some embodiments where “dilbit” is used as the solvent sprayed over the bituminous material, the “dilbit” is from about 30% to about 80% solvent by volume.

In some embodiments, the amount of solvent sprayed over the bituminous material is based on a ratio of solvent to bitumen content in the bituminous material. Accordingly, the amount of solvent used can vary based on the quality of the bituminous material (i.e., the bitumen content of the bituminous material and the pore size in the bitumen) and the solvent density or solvency power. In some embodiments, the solvent to bitumen ratio used in the spraying step 110 is from about 0.5:1 to 4:1 on a volume basis. Using a solvent to bitumen ratio within this range can help to ensure that enough solvent is sprayed over the bituminous material to dissolve a substantial portion of the bitumen content of the bituminous material.

When spraying solvent into the mixing drum containing bituminous material therein, a volume of the mixing drum will be occupied by the resulting slurry. In some embodiments, the amount of bituminous material and solvent into the mixing drum at one time is controlled in order to ensure that no greater than or no less than a specified percentage of the internal volume mixing drum is occupied. Over or under filling the mixing drum can negatively impact the mixing of the solvent and bituminous material and the dissolution of bitumen into the solvent. In some embodiments, from 20% to 60% of the volume inside the mixing drum is occupied by bituminous material and solvent.

As described above, the effect of spraying the solvent over the bituminous material is to create a slurry of material inside the mixing drum that can include two phases. The first phase is bitumen diluted in solvent (“dilbit”). The second phase is bitumen-depleted tailings. The bitumen-depleted tailings will generally include solvent, water, sand, clay, and a relatively small amount of bitumen that was not dissolved by the solvent. In some embodiments, the bitumen-depleted tailings can also include precipitated asphaltenes. Some or all of the bitumen content of the bitumen-depleted tailings can include bitumen that is occluded on the inert material of the tailings. While the rotation of the mixing drum can work to remove some of the bitumen that is stuck to the inert material (e.g., due to contact between slurry falling from the lifting shelves with slurry residing at the bottom of the mixing drum), the rotation of the drum typically does not remove all of the occluded bitumen from the inert material. Accordingly, a relatively small amount of bitumen remains with the bitumen-depleted tailings.

The rotation of the drum while the solvent is sprayed over the bituminous material can be any suitable speed that helps to promote mixing. of the solvent and the bituminous mater and the create dilbit. In some embodiments, the rotational speed is kept relatively slow in order to avoid the dispersion of the clay component of the bituminous material. High rotational speeds cause clay dispersion because of high agitation and attrition breaking up clay lenses. Clay dispersion is undesirable because clays can become suspended in the dilbit and affect dilbit quality, requiring additional clay removal steps. In some embodiments, the rotational speed of the mixing drum is kept to less than 10 rpm in order to avoid clay dispersion, although higher rotational speeds can be used.

In some embodiments, the rotation of the mixing drum continues after spraying solvent over the bituminous material inside the mixing drum has ceased. Continuing to rotate the mixing drum during and after the solvent is sprayed over the bituminous material inside the mixing drum promotes mixing of the slurry of bituminous material and solvent and the dissolution of the bitumen content of the bituminous material into the solvent as described above. In some embodiments, the mixing of the slurry by the continued rotation of the mixing drum during and after solvent is sprayed over the bituminous material can continue for a period of time sufficient to ensure that bitumen dissolution occurs and a dilbit phase is created. The specific period of time of mixing can vary based on varying factors, including the bitumen content of the bituminous material and the amount of solvent sprayed over the bituminous material. In practice, the mixing drum may be a continuously operated device with a constant feed of bituminous material and solvent to one end and a continuous discharge of dilbt and bitumen depleted material at the other end, thus providing a residence time in the drum sufficient for dissolution and separation to occur.

The injection of solvent into the mixing drum and the subsequent mixing of the solvent and the bituminous material to create dilbit can, in some embodiments, create a need for the mixing drum to include a solvent vapor recovery system. A solvent recovery system can be necessary due to the volatility of some of the solvents suitable for use in the methods described herein. Despite being injected into the mixing drum as a liquid, portions of such volatile solvents may convert to a vapor phase once inside the mixing drum, and therefore require venting from inside the mixing drum. Any solvent vapor recovery system suitable for use with a mixing drum can be used, including one or more solvent vents on the mixing drum and a solvent vapor collection vessel connected to the one or more solvent vents.

In some embodiments, the mixing drum can be a pressurized mixing drum. A pressurized mixing drum may be necessary in instances where the solvent injected into the mixing drum will not remain in a liquid state unless the mixing drum is pressurized. For example, the mixing drum can be a pressurized mixing drum when propane or butane is used in order to keep the propane and/or butane in a liquid state inside the mixing drum. Any mechanism suitable for pressurizing the mixing drum can be used.

In some embodiments, the solvent added to the bitumen material in the mixing drum can undergo pretreatment, such as heating the solvent. Additionally, heat can be applied to the bitumen material and solvent being mixed inside the mixing drum. In some embodiments, the heating of the mixing drum is accomplished by a heating source external to the mixing drum. The heating can be via indirect heating, including through the use of steam via a steam jacket on the mixing drum or direct steam injection.

The mixture of bituminous material and solvent and the creation of a slurry having dilbit and bitumen-depleted tailings is followed by a step 120 of separating the dilbit from the bitumen depleted tailings. Any technique capable of separating the dilbit from the slurry can be used (e.g., hydrocyclones, thickeners, clarifiers or filtration devices). As mentioned above, a liner screen located within the mixing drum can be used in some embodiments. The liner screen, such as a coaxial liner screen position at one end of the mixing drum, can have a mesh size that is large enough to allow the dilbit to pass through but that is small enough to keep the bitumen-depleted tailings within the liner screen. As the dilbit passes through the liner screen, the dilbit can be routed to an outlet in the mixing drum so that it can be removed from the mixing drum and used in subsequent steps of the process. Similarly, the bitumen-depleted tailings that remain within the liner screen can be transported out of the mixing drum via an outlet in the mixing drum. Once removed from the mixing drum, the bitumen-depleted tailings can be subjected to further processing, such as further contacting with solvent for additional bitumen recovery or solvent recovery.

Based on the mixing and separation steps, the dilbit obtained from the mixing drum can typically include from about 30 to about 60 wt % bitumen and from about 40 to about 70 wt % solvent. Relatively small amounts of solid material, such as sand, may also be included in the dilbit. In some embodiments, the dilbit may include from about 0 to about 3 wt % solid material. With respect to the bitumen-depleted tailings resulting from the mixing and separating steps, the bitumen-depleted tailings generally include from about 50 to about 75 wt % inert materials (such as clay and sand), from about 0 to about 5 wt % water, from about 25 to about 40 wt % solvent, and from about 3 to about 15 wt % bitumen.

Due to the undesirable presence of solid material such as fine solids or clays in the dilbit, additional steps can be taken to remove the solid material and form an essentially pure dilbit material. Any technique that removes solid material from the dilbit can be used. In some embodiments, a hydrocyclone, centrifuge, desander, switchable filter tube, filter, polymeric membrane, or screen is used to remove the solid material from the dilbit. Preferably, the hydrocyclone, centrifuge, filter, polymeric membrane, screen, etc., removes 95% or more of the solid material in the dilbit, although removal of solid material down to any level suitable for subsequent processing is also acceptable. The solid material, which will include mostly sand particles, can then be disposed of, added back with the bitumen-depleted tailings leaving the mixing drum, or be recycled back into the mixing drum in the same manner as bituminous material is fed into the mixing drum in order to attempt to recover any remaining bitumen that may be occluded on the solid material. When solid material is fed back into the mixing drum, the solid material undergoes similar or identical processing steps as those described above with respect to bituminous material.

The purified dilbit obtained after solid material is removed therefrom can be subjected to a variety of further processing steps. In some embodiments, the dilbit is transported to a storage tank where it can be added to other dilbit already collected. In some embodiments, dilbit collected in the storage tank can be used as the solvent sprayed over the bituminous material in step 110. In order to ensure that the dilbit used as solvent in step 110 has a desirable bitumen and solvent content, additional solvent can be added to the storage tank or bitumen can be removed from the storage tank. For example, if the dilbit contained in the storage tank includes 60 wt % solvent and 40 wt % bitumen but a 70% wt solvent and 30 wt % bitumen content is desired when the dilbit is used as solvent sprayed over the bituminous material in the mixing drum, then solvent can be added to the storage tank to get the dilbit in the storage tank to the correct composition. The solvent that is added to the storage tank can be any of the solvents discussed above. Any suitable manner of removing bitumen from the storage tank can be used, such as by distillation, flashing, gravity separation, and filtration with polymeric membranes.

In embodiments where the dilbit is used as a solvent and sprayed over bituminous material transported into the mixing drum in step 110, the dilbit can optionally be heated by a heating mechanism prior to being sprayed over the bituminous material. In some embodiments and depending on the boiling point of the solvent, the dilbit is heated to a temperature between 20° C. and 120° C. Any type of heater can be used to heat the dilbit to a temperature within this range, including a heat exchanger.

In instances where the solvent used in step 110 is preferably not dilbit, the dilbit in the storage tank can be processed to separate the bitumen from the solvent, at which point the separated solvent can be used as the solvent sprayed over the bituminous material in step 110. The separated bitumen can then be transported to further processing apparatus, such as apparatus used to upgrade the bitumen into commercially useful lighter hydrocarbons. Any manner of separating the dilbit into solvent and bitumen can be used, including the use of a froth tank or distillation units.

As noted above, the bitumen-depleted tailings resulting from the mixing and separating steps can include a residual amount of solvent. Therefore, in some embodiments, the bitumen-depleted tailings are treated for solvent removal and recovery. Any methods suitable for removing solvent from tailings can be used. In some embodiments, treatment for solvent removal includes washing the tailings with the same solvent that is used in the initial mixing stage. This washing can take place in a secondary mixing drum similar or identical to the one or more primary mixing drums described above and used to mix bituminous material and solvent. In some embodiments, the additional solvent used in the washing stage is in the vapor phase or is supercritical solvent. This can help to minimize the amount of solvent remaining in the tailings after the washing stage. The washing with additional solvent can be carried out in one or more washing stages. While the washing with additional solvent can remove the majority of the solvent in the tailings, some trace amounts of additional solvent may remain in the tailings. Accordingly, the tailings can be further processed for further solvent recovery, such as via a column, filtration device, or by drying or flashing to remove the solvent prior to discharge of the tailings as a final waste.

In some embodiments, the washing of the bitumen-depleted tailings with additional solvent can be carried out in the same mixing drum used for spraying the initial bituminous material with the solvent. In such embodiments, the mixing drum will typically include a screen liner so that separation of the dilbit and the bitumen-depleted tailings can be carried out within the mixing drum. In practice, washing with a additional solvent can begin by terminating the spraying of solvent into the mixing drum and removing the dilbit separated from the bitumen-depleted tailings via the screen liner from the mixing drum. The bitumen-depleted tailings can remain in the mixing drum. Additional solvent is then added to the bitumen-depleted tailings inside the mixing drum, including adding vaporous or supercritical solvent to the tailings. Rotation of the drum to promote mixing between the tailings and the additional solvent can be carried out in a similar or identical fashion as described above. The additional solvent displaces the solvent out of the tailings, where it can then pass through the screen liner located inside the mixing drum to effect separation of the solvent from the tailings. The washed tailings, which now include some trace amounts of additional solvent, remain within the screen liner and can be processed to remove trace additional solvent from the tailings, including by removing the tailings from the mixing drum and heating the tailings to the point of evaporating the trace additional solvent.

In embodiments where the mixing drum does not include a screen liner or other internal separation device, the slurry can be removed from the mixing drum and then be subjected to separation of the dilbit from the bitumen-depleted tailings. The bitumen-depleted tailings can then be transported back into the same mixing drum used for the first solvent spraying step and be subjected to further solvent washing as described above. Any suitable apparatus can be used to separate the slurry, including but not limited to, a thickener. When a thickener is used, the slurry is received by the thickener, and the thickener separates the slurry such that it produces a stream of dilbit and a stream of bitumen-depleted tailings.

FIG. 2 illustrates a process diagram of embodiments described above. Bituminous material 200 is run through a crusher 210 to reduce the size of larger pieces of the bituminous material 200. Once crushed, the bituminous material 200 is transported to a mixing drum 220 that includes a spray bar 225. As the bituminous material 200 enters the mixing drum 220, solvent is sprayed over the bituminous material 200 via the spray bar 225. The mixing drum 220 rotates during the spraying and a slurry is formed. The slurry generally contains a bitumen-enriched solvent phase and a bitumen-depleted tailings phase. A screen liner 226 inside of the mixing drum 220 works to separate the bitumen-enriched solvent phase from the bitumen-depleted tailings phase 235. The bitumen enriched solvent phase 230 leaves the mixing drum and is sent to a separation unit 240, such as a hydrocyclone. The separation unit 240 works to separate any solid material from the bitumen-enriched solvent phase 230. Accordingly, the separation unit 240 creates a purified dilbit stream 250 and a solid materials stream 260. The solid materials stream 260 is routed back to the mixing drum 226 to undergo further mixing with solvent inside the mixing drum 220. Alternatively, the solid materials stream 260 can be added back with the bitumen-depleted tailings phase 235. The purified dilbit stream 250 is sent to a storage tank 270 where several different processing steps can occur. In some instances, the dilbit stream 250 will be suitable for use as solvent that is sprayed over bituminous material inside of the mixing drum 220. In some instances, the amount of solvent and bitumen in the dilbit stream 250 will need to be adjusted, at which point bitumen 280 can be removed from the dilbit 250 in the storage tank 270 or solvent 290 can be added to the storage tank 270. In still other instances, the dilbit 250 will be separated into solvent and bitumen 280, with the solvent being sprayed over further bituminous material inside of the mixing drum 250 and the bitumen 280 being sent to an upgrader.

In some embodiments, a method of extracting bitumen from bituminous material utilizes two or more mixing drums aligned in series. With reference to FIG. 3, the method can include a step 300 of feeding a first quantity of bituminous material into a first mixing drum, a step 310 of spraying solvent over the first quantity of bituminous material inside the first mixing drum, a step 320 of separating the first quantity of bituminous material into a first dilbit stream and a first tailings stream, a step 330 of feeding the first tailings stream into a second mixing drum, a step 340 of spraying solvent over the first tailings stream inside the second mixing drum, a step 350 of separating the first tailings stream into a second dilbit stream and a second tailings stream, a step 360 of feeding a second quantity of bituminous material into the first mixing drum, and a step 370 of spraying the second dilbit stream over the second quantity of bituminous material inside the first mixing drum.

In step 300, a first quantity of bituminous material is fed into a first mixing drum. The bituminous material and the mixing drum used in step 300 may be similar or identical to the bituminous material and mixing drum described in greater detail above. Similarly, the manner of feeding the bituminous material into the first mixing drum can be similar or identical to the feeding step 100 described in greater detail above. The first quantity of bituminous material used in step 300 can be any quantity that can be processed in the mixing drum. Accordingly, the size of the mixing drum can impact the size of the first quantity of bituminous material.

In step 310, a solvent is sprayed over the first quantity of bituminous material inside the first mixing drum. Step 310 can be similar or identical to step 110 described in greater detail above, including the type and amount of solvent used, the rotation of the mixing drum during spraying, and the delivery of solvent via a spray bar extending through the mixing drum. Similarly, the result of step 310 is similar or identical to step 110 described in greater detail above. Mixing the solvent and bituminous material results in the formation of a slurry containing bitumen dissolved in solvent and solvent-wet inert material (that may or may not have some bitumen occluded thereon). In some embodiments, the solvent sprayed over the bituminous material in step 310 is paraffinic solvent.

In step 320, the first quantity of bituminous material, which is now solvent wet and in the form of the previously described slurry, is separated into a first dilbit stream and a first tailings stream. The manner of separating the slurry into these two components is similar or identical to the separation methods described above in connection with step 120. Thus, in some embodiments, the mixing drum includes a liner screen that filters the dilbit away from the tailings. Alternatively, the slurry is removed from the mixing drum and separated external to the mixing drum, such as in a thickener or hydrocyclone. The separated first dilbit stream and the first tailings stream can be similar or identical to the dilbit and tailings described above in step 120. Accordingly, the first dilbit stream can include primarily bitumen and solvent and the first tailings stream can include solvent, water, and inert materials, such as sand and clay. As also mentioned above in the discussion of step 120, the first dilbit stream can further include a relatively small amount of solid particles and the first tailings stream can include a bitumen content, including bitumen that remains occluded on the inert material and/or bitumen that is dissolved in solvent that remains with the tailings.

In step 330, the first tailings stream produced from the separation step 320 is transported and fed in to a second mixing drum. The first tailings stream can be transported to the second mixing drum in any suitable manner, including through the use of conveyors, chutes, or screw feeders. The second mixing drum can be similar or identical to the first mixing drum. While the shape and orientation of the second mixing drum is not limited, in some embodiments the second mixing drum is a horizontally positioned cylindrical drum. As with the previously described mixing drum, the second mixing drum can be capable of rotating about its axis to promote mixing between the first tailings stream and solvent injected therein, and can also include a screen liner for separating materials after mixing. The size of the second mixing drum is also not limited, and will generally be selected based on the amount of tailings to be processed inside of the second mixing drum. In some embodiments, the second mixing drum is a trommel or pulper as, described in greater detail above.

Alternatively, step 330 can be omitted. In such embodiments, the first tailings stream can remain in the first mixing drum, and further solvent processing of the tailings can be carried out in the same mixing drum used to spray first solvent over the bituminous material. If the first mixing drum does not include a mechanism for separating the slurry into a dilbit stream and a tailings stream, the slurry can be temporarily removed from the mixing drum to separate the slurry into a dilbit stream and a tailings stream, after which the tailings stream can be transported back into the first mixing drum. Any suitable method for separating the slurry external to the mixing drum can be used, including using a filter press or screening mechanism.

In step 340, solvent is sprayed over the first tailings stream inside the second mixing drum (or, in embodiments where step 330 is omitted, in the first mixing drum). The manner in which the solvent is sprayed over the first tailings stream can be similar or identical to the spraying step 110 described in greater detail above. Thus, in some embodiments, the solvent is sprayed over the first tailings stream using a spray bar that extends into the second mixing drum. Any solvent described here can be used, although in some embodiments, the solvent is dilbit. When dilbit is used as the solvent, the amount of dilbit used in step 340 can be based on the same ratios discussed above in step 110. More specifically, the amount of dilbit used in step 340 can be based on the bitumen content of the tailings, and range from a solvent (i.e., dilbit) to bitumen ratio of from 0.5:1 to 9:1 on a volume basis.

When dilbit is used as the solvent in step 340, the source of the dilbit is not limited, although in some preferred embodiments, the source of the dilbit is downstream processing steps. More specifically, and as described in greater detail below, the dilbit may be originated from an additional mixing drum located downstream from and connected in series with the first and second mixing drums. For example, where a third mixing drum is connected in series with the first and second mixing drum, the third mixing drum can receive tailings produced from the second mixing drum. Treatment of these tailings in the third mixing drum with solvent will produce dilbit, which once separated and removed from the third mixing drum, can be recycled back and used as the dilbit sprayed over the tailings in the second mixing drum. Generally speaking, dilbit produced from a mixing drum can be used as the solvent in the mixing drum immediately prior in a series of mixing drums.

In step 350, the slurry produced inside of the second mixing drum by virtue of spraying solvent over the first stream of tailings is separated into a second dilbit stream and a second tailings stream. This separation step can be similar or identical to the separation steps 330 and 120 discussed in greater detail above. Accordingly, in some embodiments, the separation is carried out by virtue of a liner screen inside of the second mixing drum that filters the second dilbit stream from the second tailings stream, while in other embodiments, the separation is carried out in a separation vessel (such as a thickener or hydrocyclone) located external to the second mixing drum. The second dilbit stream and second tailings stream produced by the separation step can be similar or identical in composition to the dilbit and tailings streams described in greater detail above. In some embodiments, the dilbit and tailings streams are lower in bitumen content then the dilbit and tailings stream produced in the first mixing drum.

Once the second mixing drum has produced a second dilbit stream, a step 360 of feeding a second quantity of bituminous material into the first mixing drum and a step 370 of spraying the second stream of dilbit over the second quantity of bituminous material inside of the first mixing drum can take place. In this manner, the overall bitumen extraction method generates its own solvent and becomes at least partially self-sufficient. The dilbit moves in a counter-flow direction to the solids and becomes more loaded with bitumen after each stage (i.e., mixing drum). Thus, the dilbit leaving the first mixing drum and which has passed through one or more downstream mixing drums reaches optimal bitumen content for further processing or separation.

Step 360 of feeding a second quantity of bituminous material into the first mixing drum can be similar or identical to step 300 and 100 described in greater detail above. Accordingly, in some embodiments, the bituminous material is oil sands and is fed into the first mixing drum using conveyor belts or the like.

Step 370 of spraying the second dilbit stream over the second quantity of bituminous material can be similar or identical to step 310 and 110 described in greater detail above. The dilbit can be sprayed over the second quantity of bituminous material using a spray bar extending into the first mixing drum, and the first mixing drum may be rotating about its axis as dilbit is sprayed over the bituminous material. Additionally, the result of this step is similar to the spraying steps described above. A slurry is formed that include bitumen dissolved in solvent and solvent-wet tailings. The slurry can be separated as described above, and a continuous process of bitumen extraction is thus established.

In some embodiments, the second stream of dilbit is subjected to a further separation step prior to being sprayed over the second quantity of bituminous material inside of the first mixing drum. The separation step generally aims to remove any solid material from the dilbit, such as sand that may have filtered through the screen liner inside of the second mixing drum. Any suitable separation method can be used to separate solid material from the second stream of dilbit. In some embodiments, the separation is carried out by processing the dilbit in a hydrocyclone, a centrifuge, filter, clarifier, desander, or through a screen.

In some embodiments, the second stream of dilbit is heated prior to being injected into the first mixing drum. For example, the second dilbit stream can be heated to a temperature in the range of from 20° C. to 40° C. prior to being sprayed over bituminous material inside of the first mixing drum. Any suitable type of heating mechanism can be used to heat the second dilbit stream, including the use of a heat exchanger.

The composition of the second stream of dilbit may also be adjusted prior to being sprayed over the second quantity of bituminous material. Thus, in scenarios where the dilbit sprayed over the bituminous material has a preferred bitumen content and solvent content, additional solvent can be added to the dilbit prior to spraying. Other processing steps to adjust the composition of the dilbit can also be used, such as removing solvent or bitumen from the dilbit.

The first dilbit stream and any other dilbit produced by the first mixing drum (such as dilbit produced after spraying the second stream of dilbit over the second quantity of bituminous material and separating the resulting slurry) can be transported to a dilbit storage unit. Dilbit in the dilbit storage unit can subsequently be processed to separate the bitumen from the solvent. Any suitable manner of carrying out such a separation can be used, such as by evaporating off the solvent. Solvent separated from the bitumen can be collected and reused in the process, while bitumen can be upgraded into lighter hydrocarbon products. In some embodiments, the dilbit leaving the first mixing drum can be subjected to solids separation such as the solids separation discussed in greater detail above prior to being stored in the dilbit storage tank. In some embodiments, the separation process uses a hydrocyclone, centrifuge, desander, switchable filter tube, or screen and removes solid material such as sand that may be contained in the dilbit upon removal from the first mixing drum.

The first dilbit stream produced from step 320 can typically include from about 30 to about 60 wt % bitumen and from about 40 to about 70 wt % solvent. Relatively small amounts of solid material, such as sand, may also be included in the first dilbit stream. In some embodiments, the first dilbit stream may include from about 0 to about 3 wt % solid material. The first tailings stream produced from step 320 can generally include from about 50 to about 75 wt % inert materials (such as clay and sand), from about 0 to about 5 wt % water, from about 25 to about 40 wt % solvent, and from about 3 to about 15 wt % bitumen. The second dilbit stream produced from step 350 can typically include less bitumen content than the first dilbit stream, such as from about 20 to about 50 wt %, and the second tailings stream can typically include less bitumen content then the first tailings stream, such as from about 1% to about 8% wt %. When the slurry produced from step 370 is separated into a dilbit stream and a tailings stream, the dilbit stream can typically have a bitumen content in the range of from 5 to 30 wt % and the tailings can have a bitumen content in the range of from 0 to 5 wt % (or greater if a solvent is used that precipitates asphaltenes).

While FIG. 3 includes two mixing steps carried out in two mixing drums, the method can include further mixing steps that utilize still additional mixing drums. For example, the bitumen-depleted tailings produced in the second mixing drum can be transported to a third mixing drum, where solvent is sprayed over the tailings, the resulting slurry is separated, and the separated dilbit is used in the first and/or second mixing drum. Ultimately, any suitable number of mixing steps and mixing drums, with the mixing drums be generally aligned in the order described above (i.e., mixing drum X+1 receives tailings from mixing drum X, and mixing drum X+1 provides a dilbit that can be used in any of the preceding mixing drums). With reference to FIG. 4, a process diagram of embodiments of the above described method is illustrated. A first mixing drum 400 is provided, which receives bituminous material 410 such as oil sand. Solvent 420 (for example, dilbit) is sprayed over the bituminous material 410 inside of the first mixing drum 400 to create a slurry that can subsequently be separated inside of the first mixing drum 400. The slurry is separated into a first tailings stream 415 and a first dilbit stream 416. The first tailings stream 415 is transported to a second mixing drum 430. Dilbit 440 originating from downstream processes is sprayed over the first tailings stream 415 inside of the second mixing drum 430 to create a slurry, although in some embodiments, fresh solvent can be used in place of dilbit 440. The slurry is then separated into the a second tailings stream 435 and a second dilbit stream 436. The second tailings stream 435 can either be subjected to further bitumen extraction processing, such as in a third mixing drum, or treated for solvent removal and deposited as waste material. The second dilbit stream 436 is transported first to a separation unit 470. The separation unit 470 removes solid material that may be present in the dilbit stream 436. The dilbit stream 436 (or a portion thereof) is then transported back to the first mixing drum 400, where it can be sprayed over additional bituminous material 410 being fed into the first mixing drum 400.

The first dilbit stream 416 leaving the first mixing drum 400 can be transported to a separation unit 450 that is similar to the separation unit 470. The separation unit 450 acts to remove solid material from the first dilbit stream 416 prior to sending the first dilbit stream 416 to a dilbit storage unit 460. From the dilbit storage unit 460, the first dilbit stream 416 can be sent to further processing units, such as unit for separating the bitumen from the solvent.

In some embodiments, systems that can be used to carry out the bitumen extraction methods described above include a first mixing drum, a first separation unit, a second mixing drum, and (optionally) a dilbit storage unit. The first mixing drum is generally similar or identical to the mixing drums described in greater detail above, and includes a first dilbit inlet, a first dilbit outlet, and a first tailings outlet. The first separation unit is also similar or identical to the separation units discussed above, and is generally used to separate solid material from dilbit that leaves the first mixing drum. The first separation unit therefore includes a second dilbit inlet that is in fluid communication with the first dilbit outlet of first mixing drum. In this manner, dilbit leaving the first mixing drum can be transported into the first separation unit. The first separation unit also includes a cleaned dilbit outlet for transporting cleaned dilbit (i.e., dilbit with less solid material than when the dilbit entered the first separation unit) out of the first separation unit, and a solid materials outlet for transporting separated solid material out of the first separation unit.

The second mixing drum is generally similar or identical to the mixing drums described in greater detail above, and includes a first tailings inlet. The first tailings inlet is in fluid communication with the first tailings outlet of the first mixing drum, and allows for the first tailings stream leaving the first mixing drum to be fed into the second mixing drum. Inside the second mixing drum the first tailings unit will be subjected to bitumen extraction by being sprayed with solvent that dissolves bitumen that remains with the first tailings and subsequently separating the dissolved bitumen from the tailings. Accordingly, the second mixing drum also includes a second dilbit outlet and a second tailings outlet for removing each component from the second mixing drum.

The second dilbit outlet of the second mixing drum is in fluid communication with the first dilbit inlet of the first mixing drum so that dilbit leaving the second mixing drum can be sprayed over bituminous material being fed into the first mixing drum. In this manner, the solvent needed for bitumen extraction in the first mixing drum is provided by the dilbit produced in the second mixing drum, and the bitumen content of the dilbit moving in a countercurrent direction through one or more mixing drums can be increased to an optimal concentration for downstream processing or separation.

The dilbit storage unit of the system includes a cleaned dilbit inlet that is in fluid communication with the cleaned dilbit outlet of the first separation unit. In this manner, the cleaned dilbit exiting the first separation unit can be transported to and stored in the dilbit storage unit. Dilbit in the dilbit storage unit can subsequently be transported to downstream processing units, such as a distillation unit for separating the solvent from the bitumen.

The system described above can also include more than two mixing drums. Any additional mixing drums are used in the same manner as the first two mixing drums. For example, a third mixing drum would receive the tailings from the second mixing drum and can be used to provide a dilbit stream that is used in the first and/or second mixing drum.

In some embodiments, the bitumen extraction method and the mixing drum configurations described above are used in conjunction with additional downstream processing. Typically, the downstream processing includes conducting further bitumen extraction processing on the bituminous material or the tailings exiting the mixing drum. By conducting further processing on the bituminous material or tailings, the overall extraction rate of bitumen from the initial bituminous material can be improved.

In some embodiments, one or more hydrocyclones are used to carry out further bitumen extraction on material exiting the mixing drum. More specifically, the one or more hydrocyclones can be used when separation of dilbit and tailings is not carried out inside of the mixing drums and instead the mixing drum outputs a slurry of solvent and bituminous material. Such a slurry is injected into a hydrocyclone, which acts to separate the dilbit from the tailings. The dilbit reports to the overflow stream of the hydrocyclone while the tailings report to the underflow of the hydrocyclone. In this manner, the mixing drum need not include separation apparatus (such as an internal screen). The dilbit leaving the hydrocyclone can be sent to a separation unit to separate the solvent from the bitumen, or can be recycled for use as a solvent in bitumen extraction. The tailings can be deposited back into the area from which the bituminous material was mined.

FIG. 5 illustrates a general schematic of a mixing drum 510 having a single hydrocyclone 520 located downstream of the mixing drum 510. In such a set up, the hydrocyclone 520 is used to separate the slurry 515 that exits the mixing drum 510 into a dilbit stream 525 and a tailings stream 526. As shown in FIG. 5, the dilbit stream 525 leaving the hydrocylcone can be sent to a separator 530 for separating the dilbit stream 525 into solvent and bitumen. The separator 530 can either perform a total separation, or as shown in FIG. 5, can remove a portion of bitumen while recycling the dilbit back to the mixing drum 510. Once the dilbit is recycled back to the mixing drum 510, it can be used in subsequent mixing steps with bituminous material inside of the mixing drum 510. The tailings stream 526 exits the bottom of the hydrocyclone 520 and can be deposited as mine backfill.

Typical hydrocyclones suitable for use in the above described method and system 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 slurry is introduced into the hydrocyclone at a direction generally perpendicular to the axis of the hydrocyclone. This induces a spiral rotation on the slurry inside the hydrocyclone and enhances the radial acceleration on the tailings within the slurry. 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 solid tailings phase is greater than that of the fluid dilbit phase, 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.

The manner of transporting the slurry from the mixing drum 516 to the hydrocyclone 520 can include any suitable mechanism for moving slurry away from the outlet of the mixing drum 510 and into the hydrocyclone 520. In some embodiments, piping is used to connect the outlet of the mixing drum 510 to the inlet of the hydrocyclone 520. A pump 530 can also be used to ensure the movement of the slurry from the mixing drum 510 to the hydrocyclone 520.

In some embodiments, including embodiments where separation of the slurry does not occur inside of the mixing drum, the slurry leaving the mixing drum is sent to a separation unit prior to being sent to the hydrocyclone. Exemplary separation units suitable for use in the method include, but are not limited to, thickeners, clarifiers, or filters. Such separation units can be desirable when clays are present in the slurry leaving the mixing drum. Separation units such as thickeners can remove these clays and produce an overflow of dilbit having reduced or eliminated clay content. The underflow of the separation unit generally includes the bitumen-depleted tailings having a solvent content, and this stream can be sent to the hydrocyclone. In some embodiments, the bitumen-depleted tails leaving a separation unit can be in the form a filter cake, in which case additional solvent can be added to the filter cake to re-slurry the material prior to sending the tailings to the hydrocyclone.

In some embodiments, two or more hydrocyclones aligned in series and located downstream of the mixing drum can be used to improve the overall amount of bitumen recovered from the slurry. The two or more hydrocyclones can use a counter current flow wherein dilbit recovered from one hydrocyclone is recycled back and added to the slurry being introduced to the previous hydrocyclone. By so doing, the overall bitumen extraction efficiency can be improved. Any number of hydrocyclones can be used in such a system, and calculations or experimentation can be carried out to determine the number of hydrocyclones necessary to maximize bitumen extraction. In some embodiments, the number of hydrocyclones used depends on how efficiently the hydrocyclones are at “washing” the dilbit from the tailings, with additional hydrocyclones necessary when the “washing” is less efficient.

FIG. 6 illustrates a system where four hydrocyclones 610, 620, 630, 640 are aligned in series downstream of the mixing drum 600. A pump 650, 651, 652, 653 is placed between the mixing drum 600 and the first hydrocyclone 610, between the first hydrocyclone 610 and the second hydrocyclone 620, between the second hydrocyclone 620 and the third hydrocyclone 630, and between the third hydrocyclone 630 and the fourth hydrocyclone 640 in order to assist in the movement of material between each of the units. The mixing drum 600 is provided for producing a slurry of bituminous material and solvent, although in some embodiments the pump box of pump 650 can serve as both the mixing drum 600 and the pump 650 when solvent and bituminous material arc fed directly into the pump 650. The hydrocyclones 610, 620, 630, 640 are provided for separating the slurry into dilbit and tailings. In the series of hydrocyclones, the tailings leaving each hydrocyclone are mixed with additional solvent (e.g., dilbit) and sent into the next hydrocyclone in the series until a tailings stream substantially free of bitumen is produced. Simultaneously, the dilbit stream leaving each hydrocyclone is sent to be mixed with the tailings entering the previous hydrocyclone in the series until a dilbit sufficiently loaded with bitumen is produced in the first hydrocyclone in the series.

Referring still to FIG. 6, in operation the method begins with introducing bituminous material 601 into the mixing drum 600 and spraying solvent 602 over the bituminous material 601 inside the mixing drum 600 as described in greater detail above. The mixing drum 600 does not include internal separation apparatus, and therefore outputs a slurry 603 including bituminous material and solvent. Enough solvent 602 is sprayed over the bituminous material 601 to ensure the slurry 603 is pumpable. While not shown in FIG. 6, the slurry can be pumped to a separation unit, such as the thickener described previously, to remove, for example, clays from the slurry and produce a tailings stream that is sent to the hydrocyclones. Pump 650 pumps the slurry 603 to the first hydrocyclone 610, where the slurry 603 is injected into the hydrocyclone 610 at a direction generally perpendicular to the axis of the hydrocyclone 610. Centrifugal forces act on the slurry 603 and separate the slurry into a first dilbit stream 611 and a first tailings stream 612. The first dilbit stream 611 can include some of the less dense solid particles of the slurry 603, and therefore can be sent to a separation unit 660 that removes fine solids from the first dilbit stream 611. In some embodiments, an objective of the hydrocyclone system is to have the first hydrocyclone 610 produce a first dilbit stream 611 that includes a solids level of less than 1000 wppm.

The first tailings stream 612 leaving the first hydrocyclone 610 is transported to the second hydrocyclone 620. Pump 651 helps to move first tailings stream 612 towards the second hydrocyclone 620 and can also serve as a mechanism for adding further dilbit to the first tailings stream 612 to ensure the first tailings stream 612 is pumpable. As discussed in greater detail below, the dilbit added to the first tailings stream 612 can come from the third hydrocyclone 630. The mixture of the first tailings stream 612 and the dilbit is transported to and injected into the second hydrocyclone 620 at a direction generally perpendicular to the axis of the second hydrocyclone 620. As with the first hydrocyclone 610, centrifugal forces act on the first tailings stream 612 to separate the first tailings stream into a second dilbit stream 621 and a second tailings stream 622. Because the slurry 603 leaving the mixing drum 600 is in a pumpable condition by virtue of the amount of solvent 602 added to the bituminous material 601 inside the mixing drum 600, the second dilbit stream 621 need not be added with the slurry 603. Instead, the second dilbit stream 621 can be used as make-up solvent to be used inside the mixing drum 600 and further load the second dilbit stream 621 with additional bitumen content. Accordingly, the second dilbit stream 621 can be transported to the mixing drum 600 and combined with solvent 602 entering the mixing drum 600. Alternatively, the second dilbit stream 621 can replace the solvent 602, thereby making the overall system generally self-sufficient (i.e., no fresh solvent is needed for the mixing drum 603 stage after start up).

The second tailings stream 622 is transported to the third hydrocylone 630 in much the same manner as the first tailings stream 612 is transported to the second hydrocyclone 620, including the use of a pump 652 to move the second tailings stream 622 towards the third hydrocyclone 630. The second tailings stream 622 can be mixed with dilbit obtained from the fourth hydrocyclone 640 in order to ensure that the second tailings stream 622 is pumpable. Once transported into the third hydrocyclone 630, the second tailings stream 622 is separated into a third dilbit stream 631 and a third tailings stream 632. As mentioned above, the third dilbit stream 631 is recycled back in the system to be added with the first tailings stream 612 being sent into the second hydrocyclone 620.

The third tailings stream 632 leaving the third hydrocyclone 630 is transported towards the fourth hydrocyclone 640. During the transport, the third tailings stream 632 can be mixed with additional tailings solids that are obtained when the first dilbit stream 611 is sent to the separation unit 660 to remove less dense solid particles that report to the overflow in the first hydrocyclone 610 rather than the underflow. The third tailings stream 632 can also be mixed with solvent to ensure the third tailings stream 632 is pumpable. The solvent will typically be a fresh solvent rather than a dilbit stream obtained from another hydrocyclone in the system. Once solvent and/or additional tailings solids are added to the third tailings stream 632, the third tailings stream 632 is injected into the fourth hydrocyclone 640 for separation into a fourth dilbit stream 641 and a fourth tailings stream 642. The fourth dilbit stream 641 can be recycled back to be mixed with the second tailings stream 622 being transported to the third hydrocyclone 630.

After the fourth hydrocyclone 640, the fourth tailings stream 642 can be in a condition where it is sufficiently stripped of bitumen material and is therefore a final waste product of the system and method. The fourth tailings stream 642 can include a solvent content, and in some embodiments, the fourth tailings stream 642 can be sent to a solvent recovery unit where the solvent is removed from the tailings. Any solvent recovery unit or system can be used to remove the solvent from the tailings, including a belt dryer to flash recover the solvent. Solvent can also be recovered using wash columns, wherein the tailings are packed in a column and solvent is displaced out of the tailings by the introduction into the column of various wash fluids.

As noted above, any number of hydrocyclones can be used to carry out the bitumen extraction. Regardless of the number of hydrocyclones used, general operating procedures can be followed. For example, the last hydrocyclone in the series will produce a tailings stream that has the lowest bitumen content of any of the tailings streams produced by the various hydrocyclones in the series and will not be sent to another hydrocyclone for the purpose of separating dilbit from the tailings. However, the tailings leaving the last hydrocylone in the series may include a solvent content that can be recovered using various solvent recovery processes. Additionally, the first hydrocyclone in the series will produce a dilbit stream that has the highest bitumen content of the any of the dilbit streams produced by the various hydrocyclones in the series, and will therefore be the dilbit stream that is treated as a product of the system rather than being recycled back into the system. In some embodiments, the dilbit from the first hydrocyclone in a series of hydrocyclones will be sent to a separation unit to separate solvent from the bitumen, and the separated bitumen will then be sent to further processing units where bitumen upgrading takes place. The solvent removed from the bitumen can be recycled back in the process. Furthermore, with the exception of the dilbit stream produced by the first hydrocyclone, the dilbit leaving each hydrocyclone in the series will be mixed with the tailings entering the preceding hydrocyclone in the series. As described above, in the case of the second hydrocyclone in the series, the dilbit can be used as the solvent for the mixing drum step rather than being added to the slurry produced by the mixing drum in order to make the overall method more self sufficient.

As noted above, dilbit from each hydrocyclone is mixed with tailings entering the previous hydrocyclone in order to ensure that the tailings are pumpable. In some embodiments, the S:B ratio used in the initial mixing drum is increased so that the dilbit obtained from each hydrocyclone has a suitably high amount of solvent to make the tailings pumpable when mixed with the dilbit. In embodiments described above where one or more mixing drums are used to extract bitumen, the S:B ratio can be within the range of 0.5:1 to 9:1. When one or more hydrocyclones are used downstream of the mixing drum, the S:B ratio used in the mixing drum can range from 1.5:1 to 10:1, although any S:B ratio that produces a pumpable slurry can be used. In addition to helping to ensure that addition of the dilbit to the tailings makes the tailings pumpable, the increased S:B ratio can also improve “wash” efficiency inside of the hydrocyclones (i.e., result in improved separation of dilbit and tailings). Each hydrocyclone in the circuit can be operated at a different S:B ratio to help accomplish these goals.

In some embodiments, a second series of hydrocyclones can be used to remove the solvent from the final tailings produced by the first series of hydrocyclones. The second series of hydrocyclones are arranged and operated in a similar or identical manner to the first series of hydrocyclones. As shown in FIG. 7, the final tailings 642 produced by the first series of hydrocyclones are mixed with a solvent mixture 721 that can be the same solvent as used previously to form a slurry. The mixture of solvent can be obtained from the overflow of the second hydrocyclone 720 in the second series of hydrocyclones. The slurry is then injected into a first hydrocyclone 710, which uses centrifugal force to separate a solvent mixture 711 from a first tailings 712. The first solvent mixture 711 of the first hydrocyclone 710 can be sent to a separation unit 740 where primary solvent is separated, while the first tailings 712 are sent to the second hydrocyclone 720. Prior to being injected into the second hydrocyclone 720, the first tailings 712 are mixed with a third solvent mixture 731 obtained from the overflow of the third (and in this case, final) hydrocyclone 730. The second hydrocyclone 720 produces a second solvent mixture 721 which, as noted previously, is mixed with the final tailings 642 from the first series of hydrocyclones, and a second tailings stream 722, which is mixed with fresh solvent and injected into the third (and in this case, final) hydrocyclone 730. The third tailings 732 produced by the third hydrocyclone 730 have the smallest amount of solvent of any of the tailings produced in the second series of hydrocyclones, and the third solvent mixture 731 is mixed with the second tailings 722.

Any of the hydrocyclones used in the methods and systems described herein can include an external heating source for heating the material inside of the hydrocyclone. The heating can be indirect heating, such as through the use of steam.

In some embodiments, the downstream processing utilizes one or more packed columns for conducting further bitumen extraction on the bitumen-depleted tailings produced by the upstream mixing drum (or mixing drums). in such embodiments, the downstream processing generally includes introducing the bitumen-depleted tailings into one or more packed columns, followed by passing solvent through the tailings packed in the column(s). As the solvent passes through the packed column(s), the solvent dissolves bitumen remaining in the tailings and carries it through and out of the column as a bitumen laden solvent. In some embodiments, the solvent used in the packed column is the same solvent used in the upstream mixing drums, such as a paraffinic solvent.

With reference to FIG. 8, the downstream processing method can include a step 800 of loading bitumen-depleted tailings in a column, a step 810 of feeding a first quantity of solvent into the column, a step 820 of collecting bitumen-enriched solvent exiting the column, and optionally, a step 830 of feeding the bitumen-enriched solvent into the column.

With reference to the step 800 of loading bitumen-depleted tailings in a column, the bitumen-depleted tailings generally include the tailings produced by the upstream mixing drum or drums. In embodiments where multiple mixing drums are used upstream of the column, the tailings can come from the last mixing drum in the series of mixing drums.

The column into which the tailings are loaded can be any type of column suitable for carrying out bitumen. In some embodiments, the column has 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. In some embodiments, the column can 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 construction for the vertical column is also not limited. Any material that will hold the bitumen material within the column can be used. The material may also preferably be a non-porous material such that various solvents fed into the column may 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 fed into the column as well as any potentially corrosive materials.

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

A wide variety of dimensions can be used for the column, including the height, inner cross sectional diameter and outer cross sectional diameter of the column. In some embodiments, the ratio of height to inner cross sectional diameter ranges from 0.25:1 to 15:1.

The tailings can be loaded in the column according to any suitable method. For example, in some embodiments, the tailings are generally loaded in the column by introducing the tailings into the column at the top end of the column. The bottom end of the column can be blocked, such as by a removable plug or by virtue of the bottom end of the column resting against the floor. In some embodiments, a metal filter screen at the bottom end of the column can be used to maintain the bitumen material in the vertical column. In such configurations, introducing the tailings at the top end of the column fills the column with tailings.

In some embodiments, the tailings loaded into the column by pouring the bitumen material into the top end of the column. In one example, tailings can be transported to the column via a conveyor having one end positioned over the top end of the column. In such a configuration, the tailings fall into the column after it is transported over the end of the conveyor positioned over the column. Manual methods of loading tailings into the column can also be used. such as mechanical or manual shoveling the tailings into column. For larger diameter columns, automatic distribution systems can be used, such as the systems disclosed in U.S. Pat. Nos. 4,555,210 and 6,729,365.

The amount of tailings loaded in the column may be such that the tailings substantially fill the column. In some embodiments, the tailings may be added to the column to occupy 90% or more of the volume of the column. In some embodiments, the tailings may not be filled to the top of the column so that room is provided to feed solvent into the column.

Generally speaking, the loading of tailings into the column as described above will lead to a well packed column. That is to say, the tailings will settle into the vertical column in manner that results in minimal void spaces within vertical column. If the vertical column is not well packed (i.e., includes too many void spaces or overly large void spaces), solvent added to the column to dissolve and extract bitumen (a step of the method described in greater detail below) will flow through the vertical column too quickly. When solvent passes through the tailings too quickly, an insufficient amount of solvation of bitumen occurs and a generally poor extraction process results.

In some embodiments, additional steps may be taken to ensure a packed column of tailings and thereby promote sufficient solvation of bitumen when solvent is passed through the tailings loaded in the column. In some embodiments, the size of individual pieces of the tailings can be reduced prior to loading the tailings into the column. Reducing the size of the pieces of the tailings may help the pieces of the tailings settle closer to each other in the column and avoid the formation of void spaces or overly large void spaces. The pieces of tailings can be reduced in size by any suitable procedure, such as by crushing or grinding the pieces. In some embodiments, the pieces are reduced in size based on the diameter of the column used. In some embodiments, the pieces are reduced to a size that is 15% or less than the diameter of the column. For example, when the column has a diameter of 40 inches, the pieces can be reduced to a size of 6 inches or less. For commercial operation the material is usually reduced to nominally 8 inches or less for ease of handling and to ensure dissolution within adequate retention time.

In other embodiments, the tailings can be packed down once it is loaded in the column in order to reduce or eliminate void spaces. Any method of packing down the tailings may be used. In some embodiments, a piston or the like is inserted into the top end of the vertical column and force is applied to the piston to move the piston downwardly into the column in order to pack down the tailings. The piston may apply pressure downwardly on the tailings loaded in the column as a consistent application of downward pressure or as a series of downward blows. Alternatively, a vibration device, such as the device disclosed in U.S. Pat. No. 3,061,278 can be used to pack down the tailings. Packing down of the tailings can also be performed manually. Additionally, packing may be allowed to occur under its own weight, including after solvent has been added to the tailings. After solvent has been added to the tailings and the bitumen has become partially solvated, the mixture of solvent and tailings can compact and slump down under its own weight. After the tailings are packed down once, additional tailings can be added to the column to take up the space in the column created by the packing. The packing down of tailings and adding of further tailings can be repeated one or more times.

In step 810, a first quantity of solvent is fed into the column. One objective of adding solvent to the column is to dissolve the bitumen content of the tailings loaded in the column. Put another way, the solvent is added to the column to reduce the viscosity of the bitumen and allow it to flow through and out of the column. Without the solvent, the bitumen content of the tailings at room temperature may have a viscosity in the range of 100,000 times that of water and will not flow through the column. The addition of the solvent reduces the viscosity of the bitumen to a flowable state and allows it to travel out of the column with the first solvent.

Accordingly, the solvent used in step 810 can be any suitable solvent for dissolving or reducing the viscosity of the bitumen in the bitumen material. In some embodiments, the first solvent includes a hydrocarbon solvent. The solvent can be the same solvent as is used when mixing solvent and bituminous material in the upstream mixing drum. In some embodiments, the solvent is a paraffinic solvent, such as pentane.

The solvent added into the column need not be 100% solvent. Other components can be included with the solvent when it is added into the column. In some embodiments, the solvent added into the column include a bitumen content. The solvent might include a bitumen content when the solvent added into the column in step 810 is solvent that has already been used to extract bitumen. As described in greater detail below, solvent that passes through tailings in a column may exit the column as bitumen-enriched solvent, and this bitumen-enriched solvent may be used to carry out step 810 being performed on a different column packed with tailings. For example, bitumen-enriched solvent collected from the bottom of a first column as described in greater detail below may be added to bitumen material loaded in a second column in order to carry out step 810 in the second column.

The solvent can be fed into the column in a wide variety of ways. For example, in some embodiments, solvent is injected into the tailings loaded in the column at various locations along the height of the column. Such injection may be accomplished through the use of column side injectors that are spaced along the height of the column and extend through the side wall of the column and into the interior of the column where the tailings are loaded. Injection of solvent at various locations along the height of the column can also be accomplished by using a single pipe that extends down into the column and includes various locations along the length of the pipe where solvent can exit the pipe. The pipe can be positioned down the center of the column or off to the side of the column.

In configurations such as those described above, the solvent may be injected into the column beginning with the lowest injection positions first and moving upwardly through the column. Injecting solvent into the column in this manner and in this order helps to ensure percolation of solvent through the column and prevents the column from plugging up as described in greater detail below.

In some embodiments, the amount of solvent added to the column is based on a ratio of solvent to bitumen content in the tailings on a v/v basis (herein referred to as “S:B”) In some embodiments, the S:B ratio is greater than 1.

As discussed above, the solvent can be injected into the column starting from the bottom of the column and moving upwards to the top of the column. Injecting the solvent into the column in this manner may beneficially prevent the column from plugging by ensuring that the S:B ratio does not fall below 1 at any location inside the column. If solvent is added at the top of the column at an S:B ratio of 1, a portion of the solvent may flow down the column to a location where the S:B ratio is below 1 and therefore does not sufficiently reduce the viscosity of the bitumen to flow through the column. This may result in the column plugging up. By introducing the solvent at an S:B ratio of at least 1 at the bottom of the column and subsequently and sequentially adding solvent at higher positions along the column at an S:B ratio greater than 1, portions of the injected solvent may not be able to flow downwardly to a location in the column where the S:B ratio is not greater than 1 and plug the column. Accordingly, the manner of injecting the solvent into the column described in greater detail above may avoid problems related to column plugging.

If the column does become plugged due to the S:B ratio falling below 1 at a location within the column, steps can be taken to unplug the column. More specifically, the location of the plug can be identified and additional solvent can be injected into the column at the injection point just below the plug (when the column is operated in a downward flow mode). The additional solvent injected into the column can be injected into the column in such a manner as to close off the bottom of the column and force the solvent to flow upwardly though the column. For example, increasing the flow rate and pressure of the injected solvent may result in closing off the bottom of the column. The upwardly moving solvent may then displace and dissolve the bitumen phase causing the plug due to the viscosity issues.

The solvent fed into the column flows downwardly through the tailings loaded in the column. The solvent flows downwardly through the height of the column via small void spaces in the tailings. The solvent may travel the flow of least resistance through the tailings. As the solvent flows through the tailings, the solvent can dissolve bitumen contained in the tailings and thereby form bitumen-enriched solvent. In some embodiments, 90%, preferably 95%, and most preferably 99% or more of the bitumen in the tailings is dissolved in the solvent and becomes part of the bitumen-enriched solvent phase.

The bitumen-enriched solvent that flows downwardly through the height of the column may exit the column at, for example, the bottom end of the column. Accordingly, a step 820 of collecting the bitumen-enriched solvent exiting the column is performed. Any method of collecting the bitumen-enriched solvent can be used, such as by providing a collection vessel at the bottom end of the column. The bottom end of the column can include a metal filter screen having a mesh size that does not permit bitumen material 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 until the bitumen-enriched solvent phase substantially or completely stops exiting the column. In some embodiments, collection is carried out for from 2 to 60 minutes.

In some embodiments, the bitumen-enriched solvent collected in step 820 contains 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 can also be included in the bitumen-enriched solvent phase.

In some embodiments, the flow of solvent through the column and the removal of bitumen-enriched solvent phase is aided by adding a pressurized gas into the column either before or after solvent is fed into the column. Applying a pressurized gas over the tailings loaded in the column can facilitate the separation of the bitumen-enriched solvent from the non-bitumen components of the tailings loaded in the vertical column. Once liberated and having a much reduced viscosity due to the addition of the solvent, the bitumen-enriched solvent phase can be pushed out of the column either by the continual addition of pressurized gas or by feeding additional solvent into the column. The addition of additional solvent or bitumen-enriched solvent collected in step 820 can displace the liberated bitumen-enriched solvent from the tailings by providing a driving force across a filtration element (i.e., the non-bituminous components of the tailings). Any suitable gas may be used. In some embodiments, the gas is nitrogen, carbon dioxide or steam. The gas can also be added over the tailings loaded in the vertical column in any suitable amount. In some embodiments, 1.8 m3 to 10.6 in3 of gas per ton of tailoings is used. This is equivalent to a range of about 4.5 liters to 27 liters of gas per liter of tailings. In certain embodiments, 3.5 m3 of gas per ton of tailings is used.

After collecting bitumen-enriched solvent, a step 830 of feeding the collected bitumen-enriched solvent back into the column can optionally be performed. The bitumen-enriched solvent phase can be fed into the column in a similar or identical manner as described above with respect to feeding a first quantity of solvent into the column. The bitumen-enriched solvent may be fed back into the column “as is” or may be diluted with additional solvent prior to feeding the bitumen-enriched solvent back into the column. The amount of bitumen-enriched solvent phase fed into the column is not limited. In some embodiments, the bitumen-enriched solvent fed into the column is approximately 0.5 to 3.0 times the amount of bitumen by volume contained in the original bitumen material.

In some embodiments, the bitumen-enriched solvent fed into the column behaves much like the first quantity of solvent fed into the column. The bitumen-enriched solvent flows downwardly through the column, dissolving additional bitumen still contained in the column and forcing any entrapped bitumen-enriched solvent out of the column. The bitumen-enriched solvent eventually may exit the column, where it may be collected in a similar or identical manner to the collection step 820 described above.

The steps of collecting bitumen-enriched solvent and feeding bitumen-enriched solvent back into the column can be repeated one or more times in order to remove greater amounts of bitumen from the tailings loaded in the column. In some examples, the steps of collecting the bitumen-enriched solvent and feeding the bitumen-enriched solvent into the column are repeated until less than 1 wt % bitumen of the bitumen material is remaining in the column.

In some embodiments, more than one column is provided for carrying out the extraction of bitumen from tailings. The columns can generally be aligned in parallel and can each receive a portion of the tailings produced in the mixing drums upstream. The bitumen-enriched solvent produced from each of the columns can be combined for further use or processing. Similarly, the tailings leaving each of the columns after bitumen extraction can be combined for further processing or disposal.

In some embodiments, the bitumen-enriched solvent obtained from processing the tailings in the columns can be used as the solvent that is sprayed over bituminous material in the upstream mixing drums. Alternatively, the bitumen-enriched solvent can be separated into a solvent phase and a bitumen phase. The bitumen-enriched solvent can also be divided such that some of the bitumen-enriched solvent is used upstream in the mixing drums, and a remaining portion is separated into solvent and bitumen.

In some embodiments, the tailings remaining in the column after solvent has been passed therethrough contain a trace amount solvent. Accordingly, further drying steps can be carried out in order to remove and recover the trace amount of solvent. Any suitable drying apparatus can be used. The drying apparatus generally operates by heating the tailings to the point of evaporating the solvent. The evaporated solvent can be collected, condensed, and reused. The dried tailings can be disposed of.

With reference to FIG. 9, a system 900 including packed columns downstream of the mixing drums is illustrated. The system 900 generally includes a mineral sizer 920, a first pulper 930, a first thickener 940, a second pulper 950, a second thickener 960, a wash column 970, and a dryer 980. While the system 900 includes, for example, two pulpers, other embodiments of the system can have fewer or more pulpers. The system 900 will generally include one thickener paired with each pulper. The system 900 can also include multiple wash columns. In some embodiments, the system 900 includes four wash column aligned in parallel.

In operation, system 900 begins with bituminous material 910, such as the bituminous material described above, being transported into the mineral sizer 920. Solvent 915, such as the solvent described above, can be injected into the mineral sizer 920 at the same time as the bituminous material 910 (as shown in FIG. 9) and/or can be mixed with the bituminous material 910 prior to its introduction into the mineral sizer 920. The mineral sizer 920 works to reduce the size of large clumps of material that may be present in the bituminous material 910, and the solvent 915 helps to begin the process of dissolving bitumen while reducing the wear on the mineral sizer.

A slurry 925 of bituminous material and solvent exits the mineral sizer 920 and is transported to the first pulper 930. In the first pulper 930, solvent is sprayed over the slurry 925 as described in greater detail above. The solvent sprayed over the slurry 925 in the pulper 930 can be a fresh stream of solvent, or, as shown in FIG. 9, can be recycle dilbit 961 obtained from the downstream second thickener 960. In some embodiments, the solvent used in the first pulper 930 is the same solvent used in the mineral sizer 915 and as will be used in the second pulper 950. When dilbit 961 is used, the solvent component of the dilbit can be same solvent used throughout the rest of the system 900.

A first pulper slurry 935 is produced as a result of the mixing of solvent and bituminous material in the first pulper 930. In some embodiments, separation of the first pulper slurry 935 into a dilbit stream and a bitumen-depleted slurry can be carried out inside of the pulper. However, as shown in FIG. 9, the first pulper slurry 935 leaves the first pulper 930 and is transported to a first thickener 940. The first thickener 940 operates to separate the first pulper slurry 935 into a dilbit stream 941 and a bitumen-depleted slurry stream 942. The dilbit stream 941 can be sent to further processing apparatus where the solvent component of the dilbit stream 941 is separated from the bitumen component. The bitumen-depleted slurry stream 942 is transported to a second pulper 950.

The second pulper 950 operates in much the same way as the first pulper 930. Solvent is sprayed over the bitumen-depleted slurry stream 942 in order to dissolvent additional bitumen content. The solvent can be clean solvent, or, ash shown in FIG. 9, can be dilbit 972 obtained from the downstream wash column 970. In some embodiments, the solvent used in the second pulper 950 (including the solvent component of the dilbit 972) is the same solvent as used throughout the system 900.

A second pulper slurry 955 is produced as a result of the mixing of solvent and bitumen-depleted slurry in the second pulper 950. In some embodiments, separation of the second pulper slurry 955 into a dilbit stream and a bitumen-depleted slurry can be carried out inside of the pulper. However, as shown in FIG. 9, the second pulper slurry 955 leaves the second pulper 950 and is transported to a second thickener 960. The second thickener 960 operates to separate the second pulper slurry 955 into a dilbit stream 961 and a bitumen-depleted slurry stream 962. The dilbit stream 961 can be sent to further processing apparatus where the solvent component of the dilbit stream 941 is separated from the bitumen component, or can be recycled back for use in the first pulper 930. The bitumen-depleted slurry stream 962 is transported to one or more downstream wash columns 970.

The bitumen depleted slurry stream 962 is loaded in the one or more wash columns 970, where solvent 971 is passed through the bitumen-depleted slurry stream 962 in order to dissolve additional bitumen and remove the bitumen from the bitumen-depleted slurry stream 962 in the form of a dilbit stream 972. The solvent 971 used in the wash column 972 can be the same solvent used through the system 900. In some embodiments, multiple wash cycles are carried out and can include recycling dilbit 972 back through the wash column 970. Once a sufficient number of wash cycles have been carried out, the dilbut 972 can be sent to separation apparatus for separating solvent from bitumen, or, as shown in FIG. 9, can be recycled back for use in the second pulper 950.

The solvent washing that takes place in the wash column 970 ultimately produces a solvent-wet tailings phase 973 that can be removed from the wash column 970 and sent to a dryer for removal of the trace amount of solvent included in the tailings phase 973. In some embodiments, the dryer 980 can operate by heating the tailings phase 973 to a temperature above the boiling point temperature of the solvent component, thereby causing the solvent to evaporate and exit the dryer 980 as a solvent vapor 981. The solvent vapor 981 can then be sent to a condenser for condensing the vapor back to a liquid so that it might be reused in the system 900. Once the solvent has been evaporated from the tailings, a dry tailings phase 982 can be discharged from the dryer and disposed of.

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) arc 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.