CA2755637A1 - Solvent treatment of paraffinic froth treatment underflow - Google Patents
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Abstract
A method is provided to recover a composition comprising asphaltenes from an oil sand compositions, the method including the steps of: contacting an oil sand composition with water to form a water and oil sand slurry; separating the water and oil sand slurry into a froth comprising mineral solids, water and a hydrocarbon phase, and an underflow stream comprising solids, water, and entrained hydrocarbons; contacting the froth with a sufficient amount of a paraffinic solvent to reach at least partial asphaltene precipitation to form a solvent diluted froth; separating the solvent--diluted froth into a hydrocarbon phase containing a majority of the paraffinic solvent, a majority of the hydrocarbons from the solvent-diluted froth, and a tailings stream containing a majority of solids and a majority of the water present in the froth wherein at least a portion of the asphaltenes from the oil sand are not in the hydrocarbon phase; contacting the tailings stream with a cyclic solvent to form a diluted tailings stream comprising an hydrocarbon phase; and separating at least a portion of the hydrocarbon phase from the diluted tailings stream wherein the hydrocarbon phase is a composition comprising asphaltenes.
Description
SOLVENT TREATMENT OF PARAFFINIC FROTH TREATMENT
UNDERFLOW
Field of the Invention The invention relates to a method and apparatus for treatment of bitumen froth treatment underflow to recover asphaltenes.
Background Oil sand is essentially a matrix of bitumen, mineral material and water, and possibly encapsulated air. The bitumen component of oil sand consists of viscous hydrocarbons which behave much like a solid at normal in situ temperatures and which act as a binder for the other components of the oil sand matrix. Oil sand will typically contain about 10%
to 12% bitumen and about 3% to 6% water, with the remainder of the oil sand being made up of mineral matter. The mineral matter component in oil sand may contain about 14% to 20% fines, measured by weight of total mineral matter contained in the deposit, but the amount of fines may increase to about 30% or more for poorer quality deposits. Oil sand extracted from the Athabasca area near Fort McMurray, Alberta, Canada, averages about 11 % bitumen, 5% water and 84% mineral matter, with about 15%
to 20% of the mineral matter being made up of fines. Oil sand deposits are mined for the purpose of extracting bitumen from them, which is then upgraded to synthetic crude oil.
The "water process" is a process for extracting bitumen from oil sand. In this process, aggressive thermal action and aggressive mechanical action are used to liberate and separate bitumen from the oil sand. An example of the water process is the hot water process. In the hot water process, oil sand is first conditioned by mixing it with hot water at about 95.degree celsius and steam in a conditioning vessel which vigorously agitates the resulting slurry in order to disintegrate the oil sand. Once the disintegration of the oil sand is complete, the slurry is separated by allowing the sand and rock to settle out. Bitumen, with air entrained in the bitumen, floats to the top of the slurry and is withdrawn as a bitumen froth. The remainder of the slurry is then treated further or scavenged by froth flotation techniques to recover bitumen that did not float to the top of the slurry during the separation step. The froth is further treated to separate solids and water from liquid hydrocarbons. An example of a hot water process is suggested in US
patent no. 5,645,714, the disclosure of which is incorporated herein.
US patent no. 5,236,577 suggests a high temperature process for treating bitumen froth where a froth is further processed by contact with a diluent at a temperature in the range of 80 to 300 C. Examples of diluents are naphtha, Varsol, and natural gas condensate.
The elevated temperature is indicated to improve the rate of separation, and to improve the ultimate product quality, as measured by decreasing the solids and water content of the treated froth.
Canadian patent number 2,232,929, the disclosure of which is incorporated herein, discloses an improvement to the hot water process that utilizes a paraffinic solvent to extract bitumen from the bitumen froth. The paraffinic solvent may be a five or six carbon number paraffin. The paraffinic solvent will dilute the bitumen, but also cause a portion of asphaltenes present in the bitumen to precipitate from the hydrocarbon phase.
Precipitation of a portion of the asphaltenes reduces the hydrocarbon yield of the process, but provides for an improved quality bitumen product. The amount of asphaltenes precipitated may be controlled by, for example, altering the ratio of solvent to bitumen. Typically, enough asphaltenes are precipitated to result in a bitumen product that contains less than about ten percent by weight asphaltenes, resulting in removal of five to ten percent of the bitumen as precipitated asphaltenes.
Canadian patent application 2682,109 suggests a process to recover asphaltenes from tailings produced by a paraffinic solvent froth treatment process. Solvent in the underflow stream from the paraffinic solvent froth treatment is first removed in a tailings solvent recovery unit (TSRU), and then two solvents are added sequentially in the TSRU underflow.
First a cyclic solvent is added, and then a polar and non-polar solvent is added to extract hydrocarbons from the tailings stream. The polar-non-polar solvent may be a mixture of alkanes such as three to ten carbon number alkanes, and either ketones or alcohols or a combination of ketones and alcohols. A
hydrocarbon phase is formed that contains the solvents and extracted hydrocarbons. The hydrocarbon phase is then separated into recyclable solvents and an asphaltene product.
Summary of the Invention A method is provided to recover a composition comprising asphaltenes from an oil sand compositions, the method comprising the steps of., contacting an oil sand composition with water to form a water and oil sand slurry; separating the water and oil sand slurry into a froth comprising mineral solids, water and a hydrocarbon phase, and an underflow stream comprising solids, water, and entrained hydrocarbons; contacting the froth with a sufficient amount of a paraffinic solvent to reach at least partial asphaltene precipitation to form a solvent diluted froth; separating the solvent-diluted froth into a hydrocarbon phase containing a majority of the paraffinic solvent, a majority of the hydrocarbons from the solvent-diluted froth, and a tailings stream containing a majority of solids and a majority of the water present in the froth wherein at least a portion of the asphaltenes from the oil sand are not in the hydrocarbon phase; contacting the tailings stream with a cyclic solvent to form a diluted tailings stream comprising an hydrocarbon phase; and separating at least a portion of the hydrocarbon phase from the diluted tailings stream wherein the hydrocarbon phase is a composition comprising asphaltenes. The composition comprising asphaltenes may also contain
UNDERFLOW
Field of the Invention The invention relates to a method and apparatus for treatment of bitumen froth treatment underflow to recover asphaltenes.
Background Oil sand is essentially a matrix of bitumen, mineral material and water, and possibly encapsulated air. The bitumen component of oil sand consists of viscous hydrocarbons which behave much like a solid at normal in situ temperatures and which act as a binder for the other components of the oil sand matrix. Oil sand will typically contain about 10%
to 12% bitumen and about 3% to 6% water, with the remainder of the oil sand being made up of mineral matter. The mineral matter component in oil sand may contain about 14% to 20% fines, measured by weight of total mineral matter contained in the deposit, but the amount of fines may increase to about 30% or more for poorer quality deposits. Oil sand extracted from the Athabasca area near Fort McMurray, Alberta, Canada, averages about 11 % bitumen, 5% water and 84% mineral matter, with about 15%
to 20% of the mineral matter being made up of fines. Oil sand deposits are mined for the purpose of extracting bitumen from them, which is then upgraded to synthetic crude oil.
The "water process" is a process for extracting bitumen from oil sand. In this process, aggressive thermal action and aggressive mechanical action are used to liberate and separate bitumen from the oil sand. An example of the water process is the hot water process. In the hot water process, oil sand is first conditioned by mixing it with hot water at about 95.degree celsius and steam in a conditioning vessel which vigorously agitates the resulting slurry in order to disintegrate the oil sand. Once the disintegration of the oil sand is complete, the slurry is separated by allowing the sand and rock to settle out. Bitumen, with air entrained in the bitumen, floats to the top of the slurry and is withdrawn as a bitumen froth. The remainder of the slurry is then treated further or scavenged by froth flotation techniques to recover bitumen that did not float to the top of the slurry during the separation step. The froth is further treated to separate solids and water from liquid hydrocarbons. An example of a hot water process is suggested in US
patent no. 5,645,714, the disclosure of which is incorporated herein.
US patent no. 5,236,577 suggests a high temperature process for treating bitumen froth where a froth is further processed by contact with a diluent at a temperature in the range of 80 to 300 C. Examples of diluents are naphtha, Varsol, and natural gas condensate.
The elevated temperature is indicated to improve the rate of separation, and to improve the ultimate product quality, as measured by decreasing the solids and water content of the treated froth.
Canadian patent number 2,232,929, the disclosure of which is incorporated herein, discloses an improvement to the hot water process that utilizes a paraffinic solvent to extract bitumen from the bitumen froth. The paraffinic solvent may be a five or six carbon number paraffin. The paraffinic solvent will dilute the bitumen, but also cause a portion of asphaltenes present in the bitumen to precipitate from the hydrocarbon phase.
Precipitation of a portion of the asphaltenes reduces the hydrocarbon yield of the process, but provides for an improved quality bitumen product. The amount of asphaltenes precipitated may be controlled by, for example, altering the ratio of solvent to bitumen. Typically, enough asphaltenes are precipitated to result in a bitumen product that contains less than about ten percent by weight asphaltenes, resulting in removal of five to ten percent of the bitumen as precipitated asphaltenes.
Canadian patent application 2682,109 suggests a process to recover asphaltenes from tailings produced by a paraffinic solvent froth treatment process. Solvent in the underflow stream from the paraffinic solvent froth treatment is first removed in a tailings solvent recovery unit (TSRU), and then two solvents are added sequentially in the TSRU underflow.
First a cyclic solvent is added, and then a polar and non-polar solvent is added to extract hydrocarbons from the tailings stream. The polar-non-polar solvent may be a mixture of alkanes such as three to ten carbon number alkanes, and either ketones or alcohols or a combination of ketones and alcohols. A
hydrocarbon phase is formed that contains the solvents and extracted hydrocarbons. The hydrocarbon phase is then separated into recyclable solvents and an asphaltene product.
Summary of the Invention A method is provided to recover a composition comprising asphaltenes from an oil sand compositions, the method comprising the steps of., contacting an oil sand composition with water to form a water and oil sand slurry; separating the water and oil sand slurry into a froth comprising mineral solids, water and a hydrocarbon phase, and an underflow stream comprising solids, water, and entrained hydrocarbons; contacting the froth with a sufficient amount of a paraffinic solvent to reach at least partial asphaltene precipitation to form a solvent diluted froth; separating the solvent-diluted froth into a hydrocarbon phase containing a majority of the paraffinic solvent, a majority of the hydrocarbons from the solvent-diluted froth, and a tailings stream containing a majority of solids and a majority of the water present in the froth wherein at least a portion of the asphaltenes from the oil sand are not in the hydrocarbon phase; contacting the tailings stream with a cyclic solvent to form a diluted tailings stream comprising an hydrocarbon phase; and separating at least a portion of the hydrocarbon phase from the diluted tailings stream wherein the hydrocarbon phase is a composition comprising asphaltenes. The composition comprising asphaltenes may also contain
2 non-asphaltenes bitumen components, and could also contain some of the aromatic and/or paraffinic solvent components, but asphaltenes may be the dominate component in this composition.
A paraffinic solvent used in paraffinic froth treatment step may comprise butane, pentane, hexane, heptanes, or mixtures thereof. A portion of asphaltenes present in the froth are partitioned from the hydrocarbon phase into a separate asphaltene phase resulting in a bitumen product that is more readily transported and processed. The cyclic solvent used in underflow treatment may be, for example, benzene, toluene, xylene, reformate or mixtures thereof. The suitable solvent could comprise cycloparaffins, for example, cyclopentane, cyclohexane or methycyclohexane. The weight ratio of cyclic solvent to recovered asphaltenes may be between about 3 to I or about 15 to 1. Recovery of an asphaltene product according to the present invention provides a product that can either be used as a fuel, or sold, and also removes this component from the tailings stream that is disposed of in, for example, a tailings pond.
Recovery of asphaltenes from the tailings stream directly from the froth separation rather than from the tailings from a tailings solvent separation unit decreases the solvent volume to be processed in the tailings solvent recovery unit, and utilizes solvent remaining with the froth separation tailings to reduce the amount of cyclic solvent required. Removal of at least a portion of bitumen and asphaltenes remaining in the tailings from the froth separation prior to the tailings being processed in the tailings solvent recovery unit according to the present invention also improves the operation of the tailings solvent recovery unit because bitumen and asphaltenes, when present in the tailings, tend to hold solvent, and increase temperatures needed to vaporize solvent as well as solvent volume to be vaporized.
Brief description of the Figure The Figure is a process flow drawing for the process of the present invention.
Detailed Description of the Invention Referring now to the Figure, an oil sand ore stream, 101, is contacted with water 102 in a mixer 120, to form a water and oil sand slurry 103. The oil sand ore can be a mined bitumen ore from a formation such as oil sands found in the Athabasca area near Fort McMurray, Alberta, Canada. The ratio of oil sand ore to water may be, for example, in the range of I to 6 or I to 2. The oil sands may contain between 75 and 95 percent by weight of mineral solids, and may contain between 10 and 20 percent by weight hydrocarbons. The hydrocarbon portion of the oil sands may have a gravity of between 7 and 10 'A PI and may contain from 10 to 25 percent by weight of asphaltenes. Other components of the hydrocarbon portion of the oil sand ore may be 10 to 40 percent by weight aliphatics, 5 to 20 percent by weight aromatics, and 10 to 50 percent by weight polar compounds. The mixer may agitate the slurry to break up solids and to increase the area of
A paraffinic solvent used in paraffinic froth treatment step may comprise butane, pentane, hexane, heptanes, or mixtures thereof. A portion of asphaltenes present in the froth are partitioned from the hydrocarbon phase into a separate asphaltene phase resulting in a bitumen product that is more readily transported and processed. The cyclic solvent used in underflow treatment may be, for example, benzene, toluene, xylene, reformate or mixtures thereof. The suitable solvent could comprise cycloparaffins, for example, cyclopentane, cyclohexane or methycyclohexane. The weight ratio of cyclic solvent to recovered asphaltenes may be between about 3 to I or about 15 to 1. Recovery of an asphaltene product according to the present invention provides a product that can either be used as a fuel, or sold, and also removes this component from the tailings stream that is disposed of in, for example, a tailings pond.
Recovery of asphaltenes from the tailings stream directly from the froth separation rather than from the tailings from a tailings solvent separation unit decreases the solvent volume to be processed in the tailings solvent recovery unit, and utilizes solvent remaining with the froth separation tailings to reduce the amount of cyclic solvent required. Removal of at least a portion of bitumen and asphaltenes remaining in the tailings from the froth separation prior to the tailings being processed in the tailings solvent recovery unit according to the present invention also improves the operation of the tailings solvent recovery unit because bitumen and asphaltenes, when present in the tailings, tend to hold solvent, and increase temperatures needed to vaporize solvent as well as solvent volume to be vaporized.
Brief description of the Figure The Figure is a process flow drawing for the process of the present invention.
Detailed Description of the Invention Referring now to the Figure, an oil sand ore stream, 101, is contacted with water 102 in a mixer 120, to form a water and oil sand slurry 103. The oil sand ore can be a mined bitumen ore from a formation such as oil sands found in the Athabasca area near Fort McMurray, Alberta, Canada. The ratio of oil sand ore to water may be, for example, in the range of I to 6 or I to 2. The oil sands may contain between 75 and 95 percent by weight of mineral solids, and may contain between 10 and 20 percent by weight hydrocarbons. The hydrocarbon portion of the oil sands may have a gravity of between 7 and 10 'A PI and may contain from 10 to 25 percent by weight of asphaltenes. Other components of the hydrocarbon portion of the oil sand ore may be 10 to 40 percent by weight aliphatics, 5 to 20 percent by weight aromatics, and 10 to 50 percent by weight polar compounds. The mixer may agitate the slurry to break up solids and to increase the area of
3 contact between the solids and the water. The mixer may also heat the slurry to a temperature of, for example, between 40 and 90 C to enhance separation of the hydrocarbons from the solids. Air and chemicals such as caustic or surfactants maybe added to the slurry to further enhance separation of the hydrocarbons from the solids. Alternatively, liberation of hydrocarbon from mineral material may be accomplished in a slurry conditioning transportation line. The water and oil sand slurry optionally may be screened in a screener 121 to remove larger solids 104 from a remaining slurry stream 105.
Remaining slurry stream 105 may be further processed to provide an initial solids separation in a first separator 123 producing an underflow stream 114, containing solids and water with some bitumen, and a froth 106. The froth contains a majority of the hydrocarbons from the oil sands stream, along with entrained water and solids. Typically, the froth contains about 60 weight percent bitumen, about 30 weight percent water, and about 10 weight percent mineral solids. The first separator may include additional steps and equipment, such as, for example, flotation cells, to increase the bitumen recovery and de-aerators to remove excessive air.
Froth, 106, from the first separator may be contacted with a paraffinic solvent, 108 to form a solvent-diluted froth 107. The solvent may cause at least some of the asphaltenes present in the froth to precipitate and to partition from the liquid hydrocarbon phase into a separate solid hydrocarbon phase.
The paraffinic solvent may contain between about 80 and 100 percent by weight of saturated hydrocarbons that do not contain rings. The paraffinic solvent may contain less than about 2 percent by weight of aromatic hydrocarbons and less than about 8 percent by weight cycloparaffins. The paraffinic solvent may include more than 90 percent by weight hydrocarbons having from four to seven carbon atoms, or optionally five or six carbon atoms. In one embodiment of the present invention, the solvent is more than 90 percent by weight pentane.
The solvent-diluted froth stream 107 may be routed to a second separator, 124, the second separator effective to separate the solvent-diluted froth into a hydrocarbon phase 110 and a tailings stream I11. The hydrocarbon phase contains a majority of the solvent present in the solvent-diluted froth feed, optionally at least 60 percent of the solvent in the solvent-diluted froth feed. The hydrocarbon phase also contains a majority of the non-asphaltene hydrocarbons present in the froth.
Optionally, the hydrocarbon phase may contain at least 70 percent to the non-asphaltene hydrocarbons present in the froth stream. The tailings stream may contain a majority of the inorganic solids and a majority of the water present in the froth along with at least a portion of any precipitated asphaltenes. In some embodiments of the invention, the tailings stream contains more than 95 percent of the solids present in the froth, and optionally at least 99 percent of the solids from the froth.
Remaining slurry stream 105 may be further processed to provide an initial solids separation in a first separator 123 producing an underflow stream 114, containing solids and water with some bitumen, and a froth 106. The froth contains a majority of the hydrocarbons from the oil sands stream, along with entrained water and solids. Typically, the froth contains about 60 weight percent bitumen, about 30 weight percent water, and about 10 weight percent mineral solids. The first separator may include additional steps and equipment, such as, for example, flotation cells, to increase the bitumen recovery and de-aerators to remove excessive air.
Froth, 106, from the first separator may be contacted with a paraffinic solvent, 108 to form a solvent-diluted froth 107. The solvent may cause at least some of the asphaltenes present in the froth to precipitate and to partition from the liquid hydrocarbon phase into a separate solid hydrocarbon phase.
The paraffinic solvent may contain between about 80 and 100 percent by weight of saturated hydrocarbons that do not contain rings. The paraffinic solvent may contain less than about 2 percent by weight of aromatic hydrocarbons and less than about 8 percent by weight cycloparaffins. The paraffinic solvent may include more than 90 percent by weight hydrocarbons having from four to seven carbon atoms, or optionally five or six carbon atoms. In one embodiment of the present invention, the solvent is more than 90 percent by weight pentane.
The solvent-diluted froth stream 107 may be routed to a second separator, 124, the second separator effective to separate the solvent-diluted froth into a hydrocarbon phase 110 and a tailings stream I11. The hydrocarbon phase contains a majority of the solvent present in the solvent-diluted froth feed, optionally at least 60 percent of the solvent in the solvent-diluted froth feed. The hydrocarbon phase also contains a majority of the non-asphaltene hydrocarbons present in the froth.
Optionally, the hydrocarbon phase may contain at least 70 percent to the non-asphaltene hydrocarbons present in the froth stream. The tailings stream may contain a majority of the inorganic solids and a majority of the water present in the froth along with at least a portion of any precipitated asphaltenes. In some embodiments of the invention, the tailings stream contains more than 95 percent of the solids present in the froth, and optionally at least 99 percent of the solids from the froth.
4 Asphaltenes may be partially partitioned from the hydrocarbon phase into a separate asphaltene phase and at least partially rejected into the tailings. This partitioning may be useful when decreasing the asphaltene content of the bitumen product increases options for marketing the bitumen. For example, the asphaltenes removed from the bitumen and not recovered with the bitumen product may be between ten and eighty percent of the asphaltenes present in the oil sand composition.
For simplicity, a single second separator is shown in the Figure, although it is to be understood that the second separator could be a series of separation stages optionally including counter-current contacting with solvent. The second separator can be tank separator(s), hydrocyclone(s), inclined plate separator(s), or their combinations. The second separator may have internals to enhance separation and material handling.
Recycle solvent 109 may be recovered from the hydrocarbon stream l 10 in a solvent recovery unit 125, leaving a bitumen product 112. The bitumen product may have less than about percent by weight asphaltene content, and less than I percent by weight water content. Some 15 solvent may optionally remain in the bitumen product, for example, to facilitate pipeline transportation of the bitumen product.
The solvent recovery unit 125 may use known methods to remove more volatile hydrocarbons from less volatile hydrocarbons such as distillation and supercritical solvent separation. The tailings solvent recovery unit may utilize known methods to remove volatile hydrocarbons from solids and/or aqueous streams such as using the heat present in the tailings stream for vaporization of the solvent.
Tailing stream 111 may be contacted with cyclic solvent 118 in contactor 126 to form a diluted tailings stream 117. The weight ratio of cyclic solvent to asphaltenes in the tailings may between 15 to I and 3 to 1. The amount of cyclic solvent used will generally be the amount necessary to provide sufficient contact between the cyclic solvent and the tailings stream rather than the amount needed based on solubility of the asphaltenes in the cyclic solvent. Thus, the weight ratio of cyclic solvent to total tailings stream may be between 1.3 to I and 0.2 to 1.
The cyclic solvent may be, for example, an aromatic such as, for example, benzene, toluene, xylene, or reformate, a cycloparaffin such as cyclopentane, cyclohexane, or methylcyclohexane, or mixtures thereof. The contactor could be, for example, a static mixer, mixing valve, mixing vessel with internals, or pump. Alternatively, the contactor may be a length of pipe within which the solvent contacts the tailings sufficiently to cause at least a portion of the asphaltenes to dissolve in the cyclic solvent. At least a portion of any paraffinic solvent that remained with the tailings stream would also be incorporated into the cyclic solvent. . The paraffinic solvent in the tailings stream may marginally reduce the amount of cyclic solvent needed to effectively remove precipitated ashphaltenes from the tailings stream.
For simplicity, a single second separator is shown in the Figure, although it is to be understood that the second separator could be a series of separation stages optionally including counter-current contacting with solvent. The second separator can be tank separator(s), hydrocyclone(s), inclined plate separator(s), or their combinations. The second separator may have internals to enhance separation and material handling.
Recycle solvent 109 may be recovered from the hydrocarbon stream l 10 in a solvent recovery unit 125, leaving a bitumen product 112. The bitumen product may have less than about percent by weight asphaltene content, and less than I percent by weight water content. Some 15 solvent may optionally remain in the bitumen product, for example, to facilitate pipeline transportation of the bitumen product.
The solvent recovery unit 125 may use known methods to remove more volatile hydrocarbons from less volatile hydrocarbons such as distillation and supercritical solvent separation. The tailings solvent recovery unit may utilize known methods to remove volatile hydrocarbons from solids and/or aqueous streams such as using the heat present in the tailings stream for vaporization of the solvent.
Tailing stream 111 may be contacted with cyclic solvent 118 in contactor 126 to form a diluted tailings stream 117. The weight ratio of cyclic solvent to asphaltenes in the tailings may between 15 to I and 3 to 1. The amount of cyclic solvent used will generally be the amount necessary to provide sufficient contact between the cyclic solvent and the tailings stream rather than the amount needed based on solubility of the asphaltenes in the cyclic solvent. Thus, the weight ratio of cyclic solvent to total tailings stream may be between 1.3 to I and 0.2 to 1.
The cyclic solvent may be, for example, an aromatic such as, for example, benzene, toluene, xylene, or reformate, a cycloparaffin such as cyclopentane, cyclohexane, or methylcyclohexane, or mixtures thereof. The contactor could be, for example, a static mixer, mixing valve, mixing vessel with internals, or pump. Alternatively, the contactor may be a length of pipe within which the solvent contacts the tailings sufficiently to cause at least a portion of the asphaltenes to dissolve in the cyclic solvent. At least a portion of any paraffinic solvent that remained with the tailings stream would also be incorporated into the cyclic solvent. . The paraffinic solvent in the tailings stream may marginally reduce the amount of cyclic solvent needed to effectively remove precipitated ashphaltenes from the tailings stream.
5 The diluted tailings 1 l7 may be processed in a tailings separator 128 to separate the diluted tailings into a hydrocarbon composition 131 and a deasphaltened tailings stream 133. The tailing separator may be, for example, a tank settler, cyclone, inclined plate separator, or centrifuge, or a combination thereof.
The deasphaltened tailings stream 133 may be processed in a tailings solvent recovery unit 129 to remove at least a portion of the solvent present in the tailings stream, producing an aromatic and paraffinc solvent stream 113, and a solvent free tailings stream 115. The recovered solvent from the tailings solvent recovery unit 113 may be combined with stream 131 and fed into distillation unit 127 The tailings solvent recovery unit 129 may be a flash vessel wherein the solvent is vaporized and recovered as paraffinic solvent stream 113. Stripping steam may be sparged into the flash vessel to provide a deeper removal of solvent. Optionally, the tailings solvent recovery unit 129 may be modified to remove the cyclic solvent and the paraffinic solvent as separate streams, for example, by removing the cyclic solvent as a side draw to a stipper which may include a reboiler to provide removal of at least a portion of the paraffinic solvent present in the side draw.
Because the present invention reduces the amount of solvent remaining in the tailings stream, it may be economical to either eliminate the tailings solvent recovery unit, or produce one solvent stream that could be recycled either to the paraffinic solvent or the cyclic solvent, or used as diluent for either produced bitumen or the produced asphaltenes stream.
The hydrocarbon composition 131, and optionally the aromatic and paraffinic solvent stream 113 from the tailings solvent recovery unit 129, may be processed in a distillation unit 127 to recover solvents. A paraffinic solvent 130 may be recovered and recycled back to froth treatment, and a cyclic solvent stream 135 may be recycled back to contactor 126. An asphaltene product stream 132 may also be produced. In an embodiment where the paraffinic solvent comprises pentanes, and the cyclic solvent comprises toluene, the separation of the two solvents by distillation is readily accomplished because of the significant separation in boiling points of the solvents. Alternatively, the aromatic and paraffinic solvent stream 113 could be combined with cyclic solvent stream 135 and recycled directly to contactor 126. The presence of some paraffinic material in the cyclic solvent stream is not harmful to the process because the amount of cyclic solvent used is limited by the need to obtain good contact between the solvent and the tailings, and therefore more cyclic solvent is needed than what would be dictated by the solubility of the asphaltenes in the cyclic solvent.
The asphaltene product stream 132 may be utilized as a fuel, gasified, or sold for other end uses for which asphaltenes are known to be useful. The present invention results in the production of the additional asphaltene product, and removes this material from the tailings stream that is ultimately disposed of in, for example, a tailings pond.
The deasphaltened tailings stream 133 may be processed in a tailings solvent recovery unit 129 to remove at least a portion of the solvent present in the tailings stream, producing an aromatic and paraffinc solvent stream 113, and a solvent free tailings stream 115. The recovered solvent from the tailings solvent recovery unit 113 may be combined with stream 131 and fed into distillation unit 127 The tailings solvent recovery unit 129 may be a flash vessel wherein the solvent is vaporized and recovered as paraffinic solvent stream 113. Stripping steam may be sparged into the flash vessel to provide a deeper removal of solvent. Optionally, the tailings solvent recovery unit 129 may be modified to remove the cyclic solvent and the paraffinic solvent as separate streams, for example, by removing the cyclic solvent as a side draw to a stipper which may include a reboiler to provide removal of at least a portion of the paraffinic solvent present in the side draw.
Because the present invention reduces the amount of solvent remaining in the tailings stream, it may be economical to either eliminate the tailings solvent recovery unit, or produce one solvent stream that could be recycled either to the paraffinic solvent or the cyclic solvent, or used as diluent for either produced bitumen or the produced asphaltenes stream.
The hydrocarbon composition 131, and optionally the aromatic and paraffinic solvent stream 113 from the tailings solvent recovery unit 129, may be processed in a distillation unit 127 to recover solvents. A paraffinic solvent 130 may be recovered and recycled back to froth treatment, and a cyclic solvent stream 135 may be recycled back to contactor 126. An asphaltene product stream 132 may also be produced. In an embodiment where the paraffinic solvent comprises pentanes, and the cyclic solvent comprises toluene, the separation of the two solvents by distillation is readily accomplished because of the significant separation in boiling points of the solvents. Alternatively, the aromatic and paraffinic solvent stream 113 could be combined with cyclic solvent stream 135 and recycled directly to contactor 126. The presence of some paraffinic material in the cyclic solvent stream is not harmful to the process because the amount of cyclic solvent used is limited by the need to obtain good contact between the solvent and the tailings, and therefore more cyclic solvent is needed than what would be dictated by the solubility of the asphaltenes in the cyclic solvent.
The asphaltene product stream 132 may be utilized as a fuel, gasified, or sold for other end uses for which asphaltenes are known to be useful. The present invention results in the production of the additional asphaltene product, and removes this material from the tailings stream that is ultimately disposed of in, for example, a tailings pond.
6 Distillation unit 127 could be multiple distillation columns, or could be a column with a side draw and optionally a stripper to remove at least a portion of the more volatile solvent from the side draw stream.
Water in the tailings stream 115 may be at least partially separated from the solids and recycled, for example, to the slurry of oil sand slurry 103. Recycling water from the tailings reduces the need to provide additional water 102. Recycling this water as hot water also provides additional heat to the front- end water extraction process and improves energy efficiency of the overall process. Alternatively, at least a portion of the heat in the tailing stream 115 can be recovered using heat exchangers before the tailings stream 115 is sent to the tailings pond.
The invention also includes the apparatus capable of performing the method.
Example Froth from a commercial oil sands facility using a water process for initial separation of mineral components from bitumen, was processed in a pilot paraffinic froth treatment facility where the froth treatment underflow was collected. The composition of the froth treatment underflow was 7% bitumen, 7% paraffinic solvent (pentanes and hexanes are the main constituents) and water + solids of 86%, all by mass.
A cyclic solvent, in this case toluene, was added to the froth treatment underflow, at a ratio of 0.6/1 toluene to underflow by volume. The mixture was homogenized, at ambient temperature, using a pitch blade turbine type impeller duel mixer, with baffles in the mixing container.
Homogenization lasted for 3 minutes with an impeller rotation speed of 600 rpm. After homogenization, the mixture was allowed to settle for 30 minutes. After settling, samples of the top hydrocarbon mixture and bottom aqueous material were collected for analysis.
The composition of the hydrocarbon phase and the aqueous phase are contained in the tables below Hydrocarbon Phase Composition by Mass (%) Solvent (paraffinic + Bitumen Water Ash toluene) 86.7 11.0 0.7 1.6 Aqueous Phase Composition by Mass (%) Paraffinic Solvent Toluene Bitumen Water + Solids 0.9 4.0 0.6 94.5
Water in the tailings stream 115 may be at least partially separated from the solids and recycled, for example, to the slurry of oil sand slurry 103. Recycling water from the tailings reduces the need to provide additional water 102. Recycling this water as hot water also provides additional heat to the front- end water extraction process and improves energy efficiency of the overall process. Alternatively, at least a portion of the heat in the tailing stream 115 can be recovered using heat exchangers before the tailings stream 115 is sent to the tailings pond.
The invention also includes the apparatus capable of performing the method.
Example Froth from a commercial oil sands facility using a water process for initial separation of mineral components from bitumen, was processed in a pilot paraffinic froth treatment facility where the froth treatment underflow was collected. The composition of the froth treatment underflow was 7% bitumen, 7% paraffinic solvent (pentanes and hexanes are the main constituents) and water + solids of 86%, all by mass.
A cyclic solvent, in this case toluene, was added to the froth treatment underflow, at a ratio of 0.6/1 toluene to underflow by volume. The mixture was homogenized, at ambient temperature, using a pitch blade turbine type impeller duel mixer, with baffles in the mixing container.
Homogenization lasted for 3 minutes with an impeller rotation speed of 600 rpm. After homogenization, the mixture was allowed to settle for 30 minutes. After settling, samples of the top hydrocarbon mixture and bottom aqueous material were collected for analysis.
The composition of the hydrocarbon phase and the aqueous phase are contained in the tables below Hydrocarbon Phase Composition by Mass (%) Solvent (paraffinic + Bitumen Water Ash toluene) 86.7 11.0 0.7 1.6 Aqueous Phase Composition by Mass (%) Paraffinic Solvent Toluene Bitumen Water + Solids 0.9 4.0 0.6 94.5
7 The bitumen recovery of this treatment is 93%.
8
Claims (13)
1. A method to recover a composition comprising asphaltenes from an oil sand compositions, the method comprising the steps of:
contacting an oil sand composition with water to form a water and oil sand slurry;
separating the water and oil sand slurry into a froth comprising mineral solids, water and a hydrocarbon phase, and an underflow stream comprising solids, water, and entrained hydrocarbons;
contacting the froth with a sufficient amount of a paraffinic solvent to reach at least partial asphaltene precipitation to form a solvent diluted froth;
separating the solvent-diluted froth into a hydrocarbon phase containing a majority of the paraffinic solvent, a majority of the hydrocarbons from the solvent-diluted froth, and a tailings stream containing a majority of solids and a majority of the water present in the froth wherein at least a portion of the asphaltenes from the oil sand are not in the hydrocarbon phase; and contacting the tailings stream with a cyclic solvent to form a diluted tailings stream comprising an hydrocarbon phase; and separating at least a portion of the hydrocarbon phase from the diluted tailings stream wherein the hydrocarbon phase is an a composition comprising asphaltenes.
contacting an oil sand composition with water to form a water and oil sand slurry;
separating the water and oil sand slurry into a froth comprising mineral solids, water and a hydrocarbon phase, and an underflow stream comprising solids, water, and entrained hydrocarbons;
contacting the froth with a sufficient amount of a paraffinic solvent to reach at least partial asphaltene precipitation to form a solvent diluted froth;
separating the solvent-diluted froth into a hydrocarbon phase containing a majority of the paraffinic solvent, a majority of the hydrocarbons from the solvent-diluted froth, and a tailings stream containing a majority of solids and a majority of the water present in the froth wherein at least a portion of the asphaltenes from the oil sand are not in the hydrocarbon phase; and contacting the tailings stream with a cyclic solvent to form a diluted tailings stream comprising an hydrocarbon phase; and separating at least a portion of the hydrocarbon phase from the diluted tailings stream wherein the hydrocarbon phase is an a composition comprising asphaltenes.
2. The method of claim 1 wherein the paraffinic solvent comprises between butane, pentane, hexane, heptane or a combination thereof.
3. The method of claim 1 wherein the paraffinic solvent comprises at least ninety percent by weight of pentane and hexane, and a ratio of paraffinic solvent to bitumen product is between 1.1 and 3.5.
4. The method of claim 2 wherein the paraffinic solvent comprises at least ninety percent by weight of pentane.
5. The method of claim 2 wherein the paraffinic solvent comprises at least ninety percent by weight of hexane.
6. The method of claim 1 further comprising the step of separating the hydrocarbon phase into a recyclable paraffinic solvent, a recyclable cyclic solvent, and a product comprising asphaltenes.
7. The method of claim 1 further comprising the step of separating the hydrocarbon phase containing a majority of the paraffinic solvent and a majority of the hydrocarbons.
8. The method of claim 1 wherein the weight ratio of cyclic solvent to bitumen is between 15 to 1 and 3 to 1.
9. The method of claim 1 wherein the cyclic solvent comprises benzene.
10. The method of claim 1 wherein the cyclic solvent comprises toluene.
11. The method of claim 1 wherein the cyclic solvent comprises xylene.
12. The method of claim 1 wherein the cyclic solvent comprises reformate.
13. The method of claim 1 wherein the cyclic solvent comprises cycloparaffins.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US40545910P | 2010-10-21 | 2010-10-21 | |
| US61/405,459 | 2010-10-21 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2755637A1 true CA2755637A1 (en) | 2012-04-21 |
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ID=45956815
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 2755637 Abandoned CA2755637A1 (en) | 2010-10-21 | 2011-10-19 | Solvent treatment of paraffinic froth treatment underflow |
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| CA (1) | CA2755637A1 (en) |
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103923686A (en) * | 2014-04-21 | 2014-07-16 | 西南石油大学 | Composite solvent for room-temperature extraction and separation of oil sand |
| US9719023B1 (en) | 2016-03-15 | 2017-08-01 | Syncrude Canada Ltd. In Trust For The Owners Of The Syncrude Project As Such Owners Exist Now And In The Future | Method for recovering solvent from froth treatment tailings with in-situ steam generation |
| US10017699B2 (en) | 2016-05-18 | 2018-07-10 | Titanium Corporation Inc. | Process for recovering bitumen from froth treatment tailings |
| US10954448B2 (en) | 2017-08-18 | 2021-03-23 | Canadian Natural Resources Limited | High temperature paraffinic froth treatment process |
| US11261384B2 (en) | 2019-09-11 | 2022-03-01 | Syncrude Canada Ltd. In Trust For The Owners Of The Syncrude Project As Such Owners Exist Now And In The Future | Recovery of hydrocarbon diluent from froth treatment tailings |
-
2011
- 2011-10-19 CA CA 2755637 patent/CA2755637A1/en not_active Abandoned
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103923686A (en) * | 2014-04-21 | 2014-07-16 | 西南石油大学 | Composite solvent for room-temperature extraction and separation of oil sand |
| US9719023B1 (en) | 2016-03-15 | 2017-08-01 | Syncrude Canada Ltd. In Trust For The Owners Of The Syncrude Project As Such Owners Exist Now And In The Future | Method for recovering solvent from froth treatment tailings with in-situ steam generation |
| US10017699B2 (en) | 2016-05-18 | 2018-07-10 | Titanium Corporation Inc. | Process for recovering bitumen from froth treatment tailings |
| US10954448B2 (en) | 2017-08-18 | 2021-03-23 | Canadian Natural Resources Limited | High temperature paraffinic froth treatment process |
| US11261384B2 (en) | 2019-09-11 | 2022-03-01 | Syncrude Canada Ltd. In Trust For The Owners Of The Syncrude Project As Such Owners Exist Now And In The Future | Recovery of hydrocarbon diluent from froth treatment tailings |
| US11566183B2 (en) | 2019-09-11 | 2023-01-31 | Syncrude Canada Ltd. In Trust For The Owners Of The Syncrude Project As Such Owners Exist Now And In The Future | Recovery of hydrocarbon diluent from froth treatment tailings |
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