Method for recovering bitumen from oil sand

Abstract

In one aspect, the present invention provides a method for recovering bitumen from an oil sand, the method comprising: (a) contacting a bitumen-containing oil sand with a first solvent mixture of cyclohexane and ethanol to provide an extraction mixture comprising a sand phase and an organic phase; (b) separating the sand phase from the organic phase comprising bitumen, ethanol and cyclohexane; (c) separating an azeotropic mixture comprising cyclohexane and ethanol from the organic phase; and (d) recovering bitumen from the organic phase. The first solvent mixture comprises from about 95 to about 65 percent cyclohexane and from about 5 to about 35 percent ethanol.

1 . A method for recovering bitumen from an oil sand, the method comprising:
 (a) contacting a bitumen-containing oil sand with a first solvent mixture of cyclohexane and ethanol to provide an extraction mixture comprising a sand phase and an organic phase, the first solvent mixture comprising from about 95 to about 65 percent cyclohexane and from about 5 to about 35 percent ethanol;   (b) separating the sand phase from the organic phase comprising bitumen, ethanol and cyclohexane;   (c) separating an azeotropic mixture comprising cyclohexane and ethanol from the organic phase; and   (d) recovering bitumen from the organic phase.   
     
     
         2 . The method according to  claim 1 , further comprising a drying step in which the organic phase is treated with a drying agent. 
     
     
         3 . The method according to  claim 2 , wherein the drying agent comprises anhydrous recovered oil sand. 
     
     
         4 . The method according to  claim 1 , wherein the first solvent mixture is used in an amount corresponding to a weight ratio of first solvent mixture to oil sand in a range from about 3 to 1 to about 500 to 1. 
     
     
         5 . The method according to  claim 1 , wherein the first solvent mixture comprises about 70 percent cyclohexane and about 30 percent ethanol. 
     
     
         6 . The method according to  claim 1 , wherein the contacting is carried for a period of time ranging from about 0.1 hour to about 24 hours. 
     
     
         7 . The method according to  claim 1 , wherein the contacting is carried out a temperature in a range from about 25° C. to about 150° C. 
     
     
         8 . The method according to  claim 1 , wherein the recovering bitumen from the organic phase is carried out prior to separating the azeotropic mixture from the organic phase. 
     
     
         9 . The method according to  claim 8 , wherein the recovering bitumen comprises centrifugation of the organic phase is carried out at a temperature in a range from about minus 40° C. to about 25° C. 
     
     
         10 . The method according to  claim 1 , wherein the recovering bitumen from the organic phase is carried out following separating the azeotropic mixture from the organic phase. 
     
     
         11 . The method according to  claim 1 , wherein the separating the azeotropic mixture is carried out by distillation at a pressure in a range from about 0.1 atmosphere to about 5 atmosphere. 
     
     
         12 . The method according to  claim 1 , wherein the separating the azeotropic mixture is carried out by distillation at ambient pressure. 
     
     
         13 . The method according to  claim 1 , further comprising a step of transporting the organic phase to a second location remote from a first location at which the contacting is carried out. 
     
     
         14 . The method according to  claim 13 , wherein the transporting comprises transport by pipeline. 
     
     
         15 . A method for recovering bitumen from an oil sand, the method comprising:
 (a) contacting in-situ a bitumen-containing oil sand in a subsurface deposit with a first solvent mixture of cyclohexane and ethanol to provide an extraction mixture, a sand phase and an organic phase, the first solvent mixture comprising from about 95 to about 65 percent cyclohexane and from about 5 to about 35 percent ethanol;   (b) removing the organic phase comprising bitumen, cyclohexane and ethanol from the subsurface deposit;   (c) separating an azeotropic mixture comprising cyclohexane and ethanol from the organic phase; and   (d) recovering bitumen from the organic phase.   
     
     
         16 . The method according to  claim 15 , wherein the order of steps (a)-(d) is first (a) then (b) then (c) then (d). 
     
     
         17 . The method according to  claim 15 , further comprising a drying step in which the organic phase is treated with a drying agent. 
     
     
         18 . The method according to  claim 15 , wherein the first solvent mixture is used in an amount corresponding to a weight ratio of first solvent mixture to oil sand in a range from about 0.5 to 1 to about 50 to 1. 
     
     
         19 . The method according to  claim 15 , wherein the separating the azeotropic mixture is carried out by distillation at a pressure in a range from about 0.1 atmosphere to about 5 atmosphere. 
     
     
         20 . A method for recovering bitumen from an oil sand, the method comprising:
 (a) contacting at ambient temperature a bitumen-containing oil sand with a first solvent mixture comprising about 69 cyclohexane and about 31 percent ethanol to provide an extraction mixture comprising a sand phase and an organic phase; the first solvent mixture being used in an amount corresponding to a weight ratio of first solvent mixture to oil sand in a range from about 3 to 1 to about 500 to 1;   (b) separating the sand phase from the organic phase comprising bitumen, ethanol and cyclohexane;   (c) separating an azeotropic mixture comprising cyclohexane and ethanol from the organic phase; and   (d) recovering bitumen from the organic phase.