Method for extracting bitumen from an oil sand stream

Abstract

The present invention provides a method for extracting bitumen from an oil sand stream that includes the steps of: providing an oil sand stream; contacting the oil sand stream with a liquid comprising a solvent thereby obtaining a solvent-diluted oil sand slurry; separating the solvent-diluted oil sand slurry, thereby obtaining a solids-depleted stream and a solids-enriched stream; increasing the S/B weight ratio of the solids-enriched stream thereby obtaining a solids-enriched stream having an increased S/B weight ratio and a liquid stream; filtering the solids-enriched stream having an increased S/B weight ratio, thereby obtaining bitumen-depleted sand. In another embodiment, the invention is a system for practicing this method.

What is claimed is: 
     
         1 . A method for extracting bitumen from an oil sand stream, the method comprising at least the steps of:
 providing an oil sand stream;   contacting the oil sand stream with a liquid comprising a solvent thereby obtaining a solvent-diluted oil sand slurry;   separating the solvent-diluted oil sand slurry, thereby obtaining a solids-depleted stream and a solids-enriched stream;   increasing the solvent-to-bitumen (S/B) weight ratio of the solids-enriched stream thereby obtaining a solids-enriched stream having an increased S/B weight ratio and a liquid stream; and   filtering the solids-enriched stream having an increased S/B weight ratio, thereby obtaining bitumen-depleted sand.   
     
     
         2 . The method of  claim 1 , wherein the solvent comprises an aliphatic hydrocarbon, preferably having from 3 to 9 carbon atoms per molecule. 
     
     
         3 . The method of  claim 2 , wherein the solvent comprises from 4 to 7 carbons per molecule, or a combination thereof. 
     
     
         4 . The method of  claim 1  wherein the solvent-diluted oil sand slurry has a solvent-to-bitumen (S/B) weight ratio of from 0.5 to 4.0. 
     
     
         5 . The method of  claim 4  wherein the solvent-diluted oil sand slurry has a solvent-to-bitumen (S/B) weight ration of from 0.7 to 3.0 
     
     
         6 . The method of  claim 5  wherein the solvent-diluted oil sand slurry has a solvent-to-bitumen (S/B) weight ration of from 0.9 to 2.5. 
     
     
         7 . The method of  claim 1  wherein the solvent-diluted oil sand slurry comprises from 10 to 60 vol. % of solids. 
     
     
         8 . The method of  claim 7  wherein the solvent-diluted oil sand slurry comprises from 20 to 40 vol. % of solids. 
     
     
         9 . The method of  claim 8  wherein the solvent-diluted oil sand slurry comprises from 25 to 35 vol. % of solids. 
     
     
         10 . The method of  claim 1  wherein the solvent is removed from the solids-depleted stream thereby obtaining a bitumen-enriched stream. 
     
     
         11 . The method of  claim 1  wherein the solids-enriched stream comprises from 30 to 65 vol. % of solids. 
     
     
         12 . The method of  claim 11  wherein the solids-enriched stream comprises from 40 to 55 vol. % of solids. 
     
     
         13 . The method of  claim 12  wherein the solids-enriched stream comprises from 45 to 55 vol. % of solids. 
     
     
         14 . The method of  claim 1  wherein at least part of the liquid stream is used in the step of contacting the oil sand stream with a liquid comprising a solvent. 
     
     
         15 . The method  claim 1  wherein the solids-enriched stream having an increased S/B weight ratio has an S/B weight ratio of from 1.5 to 8.0. 
     
     
         16 . The method  claim 15  wherein the solids-enriched stream having an increased S/B weight ratio has an S/B weight ratio of from 2.0 to 7.0. 
     
     
         17 . The method  claim 16  wherein the solids-enriched stream having an increased S/B weight ratio has an S/B weight ratio of from 2.2 to 6.0. 
     
     
         18 . The method of  claim 1  wherein in the step of filtering the solids-enriched stream, a (“first”) bitumen-enriched filtrate is obtained, which is at least partly reused in the step of contacting the oil sand stream with a liquid comprising a solvent. 
     
     
         19 . The method of  claim 18  wherein the bitumen-enriched filtrate has an S/B weight ratio of from 1.2 to 8.0. 
     
     
         20 . The method of  claim 19  wherein the bitumen-enriched filtrate has an S/B weight ratio of from 2.0 to 7.0. 
     
     
         21 . The method of  claim 20  wherein the bitumen-enriched filtrate has an S/B weight ratio of from 2.2 to 6.0. 
     
     
         22 . The method of  claim 1  wherein in the step of filtering the solids-enriched stream having an increased S/B weight ratio, a (“second”) bitumen-depleted filtrate is obtained, and the (“second”) bitumen-depleted filtrate is at least partly reused in the step of increasing the solvent-to-bitumen (S/B) weight ratio of the solids-enriched stream. 
     
     
         23 . The method of  claim 22 , wherein the bitumen-depleted filtrate has an S/B weight ratio of above 3.0. 
     
     
         24 . The method of  claim 23 , wherein the bitumen-depleted filtrate has an S/B weight ratio of above 5.0. 
     
     
         25 . A system for performing a method for extracting bitumen from an oil sand stream, the system comprising:
 a mixer for contacting an oil sand stream with a liquid, the liquid comprising a solvent, the mixer having an inlet for the oil sand stream and an outlet for a solvent-diluted oil sand slurry;   a solid/liquid separator for separating the solvent-diluted oil sand slurry, the separator having a first outlet for a solids-depleted stream and a second outlet for a solids-enriched stream;   a washer for increasing the S/B weight ratio of the solids-enriched stream, the washer having a first outlet for a solids-enriched stream having an increased S/B weight ratio and a second outlet for a liquid stream; and   a filter for filtering the solids-enriched stream having an increased S/B weight ratio, the filter having an outlet for a bitumen-depleted sand.