Process and System For Recovery of Bitumen From Oil Sands

Abstract

A process is described for bitumen extraction from oil sands. Solvent extraction is used, incorporating fines agglomeration to simplify subsequent separation. A high quality bitumen product is formed, having water and solids content that exceeds downstream processing and pipeline requirements. An embodiment of the process comprises combining a first solvent and a bituminous feed to form an initial slurry, which is optionally separated into fine solids and coarse solids. Solids are agglomerated to form an agglomerated slurry. A low solids bitumen extract from the agglomerated slurry is mixed with a second solvent to form a solvent-bitumen low solids mixture, the second solvent having a similar or lower boiling point than the first solvent. The mixture is separated to produce high grade and low grade bitumen extracts. The first and second solvents are recovered from the high grade bitumen extract, leaving a high grade bitumen product.

1 . A process for recovery of bitumen from oil sands comprising:
 combining a first solvent and a bituminous feed from oil sands to form an initial slurry;   separating the initial slurry into a fine solids stream and a coarse solids stream;   agglomerating solids from the fine solids stream to form an agglomerated slurry comprising agglomerates and a low solids bitumen extract;   separating the low solids bitumen extract from the agglomerated slurry;   mixing a second solvent with the low solids bitumen extract to form a solvent-bitumen low solids mixture, the second solvent having a similar or lower boiling point than the first solvent;   subjecting the mixture to gravity separation to produce a high grade bitumen extract and a low grade bitumen extract; and   recovering the first and second solvent from the high grade bitumen extract, leaving a high grade bitumen product.   
     
     
         2 . The process of  claim 1 , additionally comprising recovering the first solvent from the coarse solids stream prior to agglomerating. 
     
     
         3 . The process of  claim 1 , wherein the ratio of the first solvent to bitumen in the initial slurry is selected to avoid precipitation of asphaltenes during agglomeration. 
     
     
         4 . The process of  claim 3 , wherein the ratio of solvent to bitumen during agglomeration is less than 2:1. 
     
     
         5 . The process of  claim 1 , wherein agglomerating solids comprises adding an aqueous bridging liquid to the fine solids stream and providing agitation. 
     
     
         6 . The process of  claim 1 , additionally comprising adding steam to the bituminous feed before combining with the first solvent, to increase the temperature of the bituminous feed to a temperature of from about 0° C. to about 60° C., or is from about 0° C. to about 30° C. 
     
     
         7 . The process of  claim 1 , wherein the initial slurry is formed in a low oxygen environment. 
     
     
         8 . The process of  claim 1 , wherein the coarse solids stream is combined with the agglomerated slurry prior to separating the low solids bitumen extract from the agglomerated slurry. 
     
     
         9 . The process of  claim 1 , wherein the first solvent comprises a paraffinic solvent, a cyclic aliphatic hydrocarbon, or a mixture thereof;
 wherein the paraffinic solvent comprises an alkane, a natural gas condensate, a distillate from a fractionation unit, or a combination thereof containing more than 40% small chain paraffins of 5 to 10 carbon atoms;   wherein the alkane comprises heptane, iso-heptane, hexane, iso-hexane, pentane, iso-pentane, or a combination thereof; and   wherein the cyclic aliphatic hydrocarbon comprises a cycloalkane of 4 to 9 carbon atoms.   
     
     
         10 . The process of  claim 9 , wherein the distillate from a fractionation unit has a final boiling point of less than about 180° C., or less than about 100° C. 
     
     
         11 . The process of  claim 1 , wherein the boiling point of the second solvent is less than 100° C. 
     
     
         12 . The process of  claim 1 , wherein the first solvent and second solvent are the same. 
     
     
         13 . The process of  claim 1 , wherein the agglomerated slurry is separated into the low solids bitumen extract and agglomerates in a solid-liquid separator, and the solid-liquid separator comprises a secondary stage for countercurrently washing the agglomerates separated from the agglomerated slurry. 
     
     
         14 . The process of  claim 1 , wherein the first solvent recovered from the high grade bitumen extract comprises entrained bitumen, and is re-used for combining with the bituminous feed or for including with the fine solids stream during agglomeration. 
     
     
         15 . A process for recovery of bitumen from oil sands comprising:
 combining a first solvent and a bituminous feed from oil sands to form an initial slurry;   separating the initial slurry into a fine solids stream and a coarse solids stream;   agglomerating solids from the fine solids stream to form an agglomerated slurry comprising agglomerates and a low solids bitumen extract;   mixing a second solvent with the agglomerated slurry to form a solvent-bitumen agglomerated slurry mixture, the second solvent having a similar or lower boiling point than the first solvent;   subjecting the mixture to separation to produce a high grade bitumen extract and a low grade bitumen extract;   recovering the first and second solvent from the high grade bitumen extract, leaving a high grade bitumen product; and   recovering the first and second solvent from the low grade bitumen extract, leaving a low grade bitumen product.   
     
     
         16 . The process of  claim 15 , additionally comprising recovering the first solvent from the coarse solids stream prior to agglomerating. 
     
     
         17 . The process of  claim 15 , wherein the ratio of the first solvent to bitumen in the initial slurry is selected to avoid precipitation of asphaltenes during agglomerating. 
     
     
         18 . The process of  claim 15 , wherein agglomerating solids comprises adding an aqueous bridging liquid to the fine solids stream and providing agitation. 
     
     
         19 . The process of  claim 15 , additionally comprising adding steam to the bituminous feed before combining with the first solvent, to increase the temperature of the bituminous feed to a temperature of from about 0° C. to about 60° C., or is from about 0° C. to about 30° C. 
     
     
         20 . The process of  claim 15 , wherein the initial slurry is formed in a low oxygen environment. 
     
     
         21 . The process of  claim 15 , wherein the coarse solids stream is combined with the agglomerated slurry prior to mixing the second solvent with the agglomerated slurry. 
     
     
         22 . The process  claim 15 , wherein the first solvent comprises a paraffinic solvent, a cyclic aliphatic hydrocarbon, or a mixture thereof;
 wherein the paraffinic solvent comprises an alkane, a natural gas condensate, a distillate from a fractionation unit, or a combination thereof containing more than 40% small chain paraffins of 5 to 10 carbon atoms;   wherein the alkane comprises heptane, iso-heptane, hexane, iso-hexane, pentane, iso-pentane, or a combination thereof; and   wherein the cyclic aliphatic hydrocarbon comprises a cycloalkane of 4 to 9 carbon atoms.   
     
     
         23 . The process of  claim 22 , wherein the distillate from a fractionation unit has a final boiling point of less than about 180° C., or less than about 100° C. 
     
     
         24 . The process of  claim 15 , wherein the boiling point of the second solvent is less than 100° C. 
     
     
         25 . The process of  claim 15 , wherein the second solvent is immiscible or can be rendered immiscible in the first solvent. 
     
     
         26 . The process of  claim 15 , wherein the high grade bitumen extract and the low grade bitumen extract are separated in a solid-liquid separator, and
 the solid-liquid separator comprises a secondary stage for countercurrently washing agglomerates separated from the solvent-bitumen agglomerated slurry mixture.   
     
     
         27 . The process of  claim 15 , wherein the first solvent recovered from the high grade bitumen extract comprises entrained bitumen, and is re-used for combining with the bituminous feed or for including with the fine solids stream during agglomeration. 
     
     
         28 . A process for recovery of a bitumen product from oil sands comprising:
 combining a first solvent and a bituminous feed from oil sands to form an initial slurry;   agglomerating solids from initial slurry to form an agglomerated slurry comprising agglomerates and a low solids bitumen extract;   mixing a second solvent with the agglomerated slurry to form a solvent-bitumen agglomerated slurry mixture, the second solvent having a similar or lower boiling point than the first solvent;   subjecting the mixture to separation to produce a high grade bitumen extract and a low grade bitumen extract comprising substantially all solids and water; and   recovering the first and second solvent from the high grade bitumen extract, leaving a high grade bitumen product;   wherein the ratio of first solvent to bitumen in the initial slurry is selected to avoid precipitation of asphaltenes during agglomeration.   
     
     
         29 . The process of  claim 28 , additionally comprising recovering solvent from the low grade bitumen extract, leaving a low grade bitumen product. 
     
     
         30 . The process of  claim 28 , additionally comprising separating the low solids bitumen extract from the agglomerated slurry. 
     
     
         31 . The process of  claim 28 , wherein the ratio of solvent to bitumen during agglomeration is less than 2:1. 
     
     
         32 . The process of  claim 28 , additionally comprising adding steam to the bituminous feed before combining with the first solvent, to increase the temperature of the bituminous feed to a temperature of from about 0° C. to about 60° C., or is from about 0° C. to about 30° C. 
     
     
         33 . The process of  claim 28 , wherein the initial slurry is formed in a low oxygen environment. 
     
     
         34 . The process of  claim 28 , wherein the first solvent comprises a paraffinic solvent, a cyclic aliphatic hydrocarbon, or a mixture thereof;
 wherein the paraffinic solvent comprises an alkane, a natural gas condensate, a distillate from a fractionation unit, or a combination thereof containing more than 40% small chain paraffins of 5 to 10 carbon atoms;   wherein the alkane comprises heptane, iso-heptane, hexane, iso-hexane, pentane, iso-pentane, or a combination thereof; and   wherein the cyclic aliphatic hydrocarbon comprises a cycloalkane of 4 to 9 carbon atoms.   
     
     
         35 . The process of  claim 34 , wherein the distillate from a fractionation unit has a final boiling point of less than about 180° C., or less than about 100° C. 
     
     
         36 . The process of  claim 28 , wherein the boiling point of the second solvent is less than 100° C. 
     
     
         37 . The process of  claim 28 , wherein the second solvent is immiscible or can be rendered immiscible in the first solvent. 
     
     
         38 . The process of  claim 28 , wherein the high grade bitumen extract and the low grade bitumen extract are separated in a solid-liquid separator, and the solid-liquid separator comprises a secondary stage for countercurrently washing agglomerates separated from the solvent-bitumen agglomerated slurry mixture. 
     
     
         39 . The process of  claim 28 , wherein the first solvent recovered from the high grade bitumen extract comprises entrained bitumen, and is re-used for combining with the bituminous feed or for including with the initial slurry during agglomeration. 
     
     
         40 . A system for recovery of bitumen from oil sands comprising:
 a slurry system wherein a bituminous feed is mixed with a first solvent to form an initial slurry;   an agglomerator for agglomerating solids and producing an agglomerated slurry;   a primary solid-liquid separator for separating the agglomerated slurry into agglomerates and a low solids bitumen extract;   a gravity separator for receiving the low solids bitumen extract and a second solvent; and   a primary solvent recovery unit for recovering the first solvent or the second solvent in a high grade bitumen extract arising from the gravity separator and for separating bitumen therefrom.   
     
     
         41 . The system of  claim 40 , additionally comprising a fine/coarse solids separator in fluid communication with the slurry system for receiving the initial slurry and separating a fine solids stream therefrom, and wherein the agglomerator is for agglomerating the fine solids stream therein. 
     
     
         42 . The system of  claim 40 , additionally comprising a secondary solid-liquid separator for countercurrently washing agglomerates received from the primary solid-liquid separator. 
     
     
         43 . The system of  claim 42 , wherein the primary or the secondary solid-liquid separator comprises a gravity separator, cyclone, screen, or belt filter. 
     
     
         44 . The system of  claim 40 , additionally comprising a secondary solvent recovery unit for recovering solvent from the agglomerates separated in the primary solid-liquid separator. 
     
     
         45 . The system of  claim 40 , additionally comprising a steam source for pre-conditioning feed entering the slurry system. 
     
     
         46 . The system of  claim 41 , additionally comprising means for directing a coarse solids stream derived from the fine/coarse solids separator for combination with the agglomerated slurry arising from the agglomerator prior to entry of the slurry into the primary solid-liquid separator. 
     
     
         47 . The system of  claim 40 , wherein the slurry system comprises a mix box, a pump, a pipeline or a combination thereof, having a feed section for a gas blanket to provide a low oxygen environment. 
     
     
         48 . The system of  claim 40 , wherein the primary solid-liquid separator comprises a settling vessel, cyclone, or screen.