Method for extracing bitumen from an oil sand feed stream

Abstract

The present invention provides a method for extracting bitumen from an oil sand feed stream, the method including at least the steps of: (a) providing an oil sand feed stream; (b) contacting the oil sand feed stream with a hydrocarbon solvent thereby obtaining a solvent-diluted oil sand slurry; (c) filtering the solvent-diluted oil sand slurry thereby obtaining a solids-enriched stream and a filtrate; and (d) removing at least a part of the hydrocarbon solvent from the solids-enriched stream thereby obtaining a solvent-depleted solids-enriched stream, wherein in step (d) the at least part of the hydrocarbon solvent is removed from the solids-enriched stream by purging with a gas stream at a gas/solids weight ratio (related to the solids-enriched stream) of at most 3.0%.

We claim: 
     
         1 . A method for extracting bitumen from an oil sand feed stream, the method comprising at least the steps of:
 (a) providing an oil sand feed stream;   (b) contacting the oil sand feed stream with a hydrocarbon solvent thereby obtaining a solvent-diluted oil sand slurry;   (c) filtering the solvent-diluted oil sand slurry thereby obtaining a solids-enriched stream and a filtrate; and   (d) removing at least a part of the hydrocarbon solvent from the solids-enriched stream thereby obtaining a solvent-depleted solids-enriched stream,
 wherein in step (d) said at least part of the hydrocarbon solvent is removed from the solids-enriched stream by purging with a gas stream at a gas/solids weight ratio (related to the solids-enriched stream) of at most 3.0%. 
   
     
     
         2 . The method according to  claim 1 , wherein the hydrocarbon solvent used in step (b) comprises a hydrocarbon having from 3 to 9 carbon atoms per molecule. 
     
     
         3 . The method according to  claim 1 , wherein the hydrocarbon solvent used in step (b) comprises an aliphatic hydrocarbon having 3 to 9 carbon atoms per molecule. 
     
     
         4 . The method according to any  claim 2 , wherein the hydrocarbon solvent used in step (b) comprises at least 90 wt. % of an aliphatic hydrocarbon having 3 to 9 carbon atoms per molecule. 
     
     
         5 . The method according to  claim 1 , wherein in step (c) the solvent-diluted oil sand slurry is deposited as a filter cake on a filter medium and wherein during filtering the pressure above the filter cake is at least 1.7 bara. 
     
     
         6 . The method according to  claim 5 , wherein the pressure of the solids-enriched stream obtained in step (c) is lowered to below 1.2 barg. 
     
     
         7 . The method according to  claim 5 , wherein the pressure of the solids-enriched stream obtained in step (c) is lowered to below 0.1 barg. 
     
     
         8 . The method according to  claim 5 , wherein during the filtering in step (c) the pressure above the filter cake is in the range of from 1.7 to 5.0 bara. 
     
     
         9 . The method according to  claim 5 , wherein during the filtering in step (c) the pressure above the filter cake is in the range of from 2.4 to 4.0 bara. 
     
     
         10 . The method according to  claim 5 , wherein during the filtering in step (c) the pressure difference over the filter cake is below 4.0 bar. 
     
     
         11 . The method according to  claim 5 , wherein during the filtering in step (c) the pressure difference over the filter cake is below 3.0 bar. 
     
     
         12 . The method according to  claim 1 , wherein hydrocarbon solvent is removed from the filtrate thereby obtaining a bitumen-enriched stream. 
     
     
         13 . The method according to  claim 1 , wherein in step (d) the hydrocarbon solvent is removed by purging with the gas stream at a gas/solids weight ratio (related to the solids-enriched stream) of at most 2.0%. 
     
     
         14 . The method according to  claim 1 , wherein in step (d) the hydrocarbon solvent is removed by purging with the gas stream at a gas/solids weight ratio (related to the solids-enriched stream) of at most 0.5%. 
     
     
         15 . The method according to  claim 1 , wherein the solvent-depleted solids-enriched stream obtained in step (d) comprises at least 1.0 wt. % water, based on the solvent-depleted solids-enriched stream. 
     
     
         16 . The method according to  claim 1 , wherein the solvent-depleted solids-enriched stream obtained in step (d) comprises at least 2.0 wt. % water, based on the solvent-depleted solids-enriched stream. 
     
     
         17 . The method according to  claim 1 , wherein the solvent-depleted solids-enriched stream obtained in step (d) has a water content (relative to present mineral solids) that is at most 1.0 wt. % lower than the water content of the oil sand feed stream provided in step (a). 
     
     
         18 . The method according to  claim 1 , wherein the solvent-depleted solids-enriched stream obtained in step (d) has a hydrocarbon solvent content of at most 0.025 wt. %. 
     
     
         19 . The method according to  claim 1 , wherein the solvent-depleted solids-enriched stream obtained in step (d) has a hydrocarbon solvent content of at most 0.010 wt. %.