Low energy process for extraction of bitumen from oil sand

Abstract

An improved low energy extraction process for recovering bitumen from oil sand whereby essentially all of the thermal energy input for processing the oil sand takes place at the slurry mixing step as opposed to at both the slurry mixing step and the slurry flooding step. Mined oil sand is mixed with sufficient hot slurry water to produce an oil sand slurry having a density in the preferred range of about 1.50 g/cc to about 1.60 g/cc and a temperature in the preferred range of about 40° C. to about 55° C., more preferably greater than about 43° C. The oil sand slurry is conditioned, preferably by pumping it through a pipeline for a sufficient length of time, and then flooded with cold flood water to produce a diluted slurry having a density in the range of about 1.4 g/cc to about 1.5 g/cc and a temperature generally below 40° C. and typically in the range of about 30° C. to about 35° C. The diluted slurry is introduced into a gravity separation vessel where bitumen froth is recovered.

1 . A method for recovering bitumen from oil sand, comprising: 
 dry mining oil sand at a mine site;    mixing the oil sand with sufficient hot slurry water to produce an oil sand slurry containing bitumen, sand, water and entrained air, the oil sand slurry having a density in the range of about 1.50 g/cc to about 1.65 g/cc and a temperature in the range of about 40° C. to about 70° C.;    conditioning the oil sand slurry;    flooding the conditioned oil sand slurry with cold flood water to produce a diluted slurry; and    introducing the diluted slurry into a gravity separation vessel wherein separate layers of bitumen froth, middlings and sand tailings are formed; and    separately removing bitumen froth, middlings and sand tailings from the vessel.    
   
   
       2 . The method as set forth in  claim 1  wherein the hot slurry water has a temperature in the range of about 70° C. to about 95° C.  
   
   
       3 . The method as set forth in  claim 1  wherein the oil sand slurry has a temperature in the range of about 40° C. to about 55° C.  
   
   
       4 . The method as set forth in  claim 3  wherein the oil sand slurry has a temperature greater than about 43° C.  
   
   
       5 . The method as set forth in  claim 1  wherein the oil sand slurry has a temperature in the range of about 40° C. to about 50° C.  
   
   
       6 . The method as set forth in  claim 1  wherein the oil sand slurry has a temperature in the range of about 40° C. to about 45° C.  
   
   
       7 . The method as set forth in  claim 1  wherein caustic is added during the mixing step.  
   
   
       8 . The method as set forth in  claim 1  wherein the conditioning step comprises pumping the oil sand slurry through a pipeline.  
   
   
       9 . The method as set forth in  claim 8  wherein the pipeline has sufficient length so that a slurry retention time therein is at least 10 minutes.  
   
   
       10 . The method as set forth in  claim 1  wherein the conditioning step comprises retaining the oil sand slurry in a tumbler or agitation tank.  
   
   
       11 . The method as set forth in  claim 10  wherein the slurry retention time in the tumbler and/or agitation tank is between about 7 minutes to about 12 minutes.  
   
   
       12 . The method as set forth in  claim 1  wherein the oil sand slurry has a density in the range of about 1.50 g/cc to about 1.60 g/cc.  
   
   
       13 . The method as set forth in  claim 1  wherein the diluted slurry has a density in the range of about 1.4 g/cc to about 1.5 g/cc.  
   
   
       14 . The method as set forth in  claim 13  wherein the diluted slurry has a density in the range of about 1.45 g/cc to about 1.5 g/cc.  
   
   
       15 . The method as set forth in  claim 1  wherein the cold flood water has a temperature in the range of about 2° C. to about 50° C.  
   
   
       16 . The method as set forth in  claim 1  wherein the cold flood water has a temperature in the range of about 2° C. to about 27° C.  
   
   
       17 . The method as set forth in  claim 1  wherein the flood water has a temperature in the range of about 5° C. to about 10° C.  
   
   
       18 . The method as set forth in  claim 1  wherein the diluted slurry has a temperature in the range of about 25° C. to about 40° C.  
   
   
       19 . The method as set forth in  claim 1  wherein the diluted slurry has a temperature in the range of about 30° C. to 35° C.  
   
   
       20 . The method as set forth in  claim 1  comprising: 
 heating bitumen in the vessel by adding heated water as an underwash layer immediately beneath the bitumen froth layer.    
   
   
       21 . The method as set forth in  claim 1  wherein the oil sand is of about low to average grade.  
   
   
       22 . The method as set forth in  claim 1  wherein the oil sand slurry has a density in the range of about 1.55 g/cc to about 1.60 g/cc.  
   
   
       23 . The method as set forth in  claim 1  wherein the mixing step occurs in a mix box or cyclofeeder.