Apparatus and method for recovering a hydrocarbon diluent from tailings

Abstract

An apparatus and a method for separating diluted tailings containing a hydrocarbon diluent into a recovered diluent component and a diluent recovered tailings component. The method includes introducing the diluted tailings into a diluent recovery vessel so that they form a tailings pool in the diluent recovery vessel, introducing an amount of steam directly into the tailings pool, mixing the diluted tailings which are contained in the tailings pool, and maintaining the diluted tailings in the diluent recovery vessel for a residence time. The apparatus includes a diluent recovery vessel having a tailings pool section, a steam distributor located in the tailings pool section, and a mixing device associated with the tailings pool section.

1 . A method of separating a diluted tailings comprising a hydrocarbon diluent into a recovered diluent component and a diluent recovered tailings component, wherein the diluted tailings are derived from a bitumen froth treatment process, the method comprising:
 (a) introducing the diluted tailings into an interior of a diluent recovery vessel so that the diluted tailings form a tailings pool in a tailings pool section of the diluent recovery vessel;   (b) introducing an amount of steam directly into the tailings pool;   (c) mixing the diluted tailings which are contained in the tailings pool;   (d) maintaining the diluted tailings in the diluent recovery vessel for a residence time in order to separate the diluted tailings into the recovered diluent component and the diluent recovered tailings component;   (e) recovering the recovered diluent component from the diluent recovery vessel; and   (f) recovering the diluent recovered tailings component from the diluent recovery vessel.   
     
     
         2 . The method as claimed in  claim 1  wherein the interior of the diluent recovery vessel has an absolute pressure of between 20 kPa and 120 kPa. 
     
     
         3 . The method as claimed in  claim 1  wherein the interior of the diluent recovery vessel has a temperature of between 40 degrees Celsius and 120 degrees Celsius. 
     
     
         4 . The method as claimed in  claim 1  wherein introducing the steam directly into the tailings pool is comprised of distributing the steam throughout the tailings pool with a steam distributor located in the tailings pool. 
     
     
         5 . The method as claimed in  claim 4  wherein the steam distributor is configured so that the steam is introduced directly into the tailings pool in a direction toward a lower end of the diluent recovery vessel. 
     
     
         6 . The method as claimed in  claim 1  wherein the residence time is between 1 minute and 50 minutes. 
     
     
         7 . The method as claimed in  claim 1  wherein mixing the diluted tailings is comprised of stirring the diluted tailings. 
     
     
         8 . The method as claimed in  claim 1  wherein mixing the diluted tailings is comprised of passing the diluted tailings through a recirculation circuit which is in communication with the tailings pool. 
     
     
         9 . The method as claimed in  claim 8  wherein mixing the diluted tailings is further comprised of stirring the diluted tailings. 
     
     
         10 . The method as claimed in  claim 7  wherein stirring the diluted tailings is performed at a stirring intensity of between 0.05 watts per kilogram and 40 watts per kilogram. 
     
     
         11 . The method as claimed in  claim 10  wherein stirring the diluted tailings is performed at a stirring intensity of between 1.5 watts per kilogram and 10 watts per kilogram. 
     
     
         12 . The method as claimed in  claim 8  wherein the diluted tailings are introduced into the diluent recovery vessel at a feed rate by weight, wherein the diluted tailings are passed through the recirculation circuit at a recirculation rate by weight, and wherein the recirculation rate is between 5 percent and 50 percent of the feed rate. 
     
     
         13 . The method as claimed in  claim 12  wherein the recirculation rate is between 10 percent and 20 percent of the feed rate. 
     
     
         14 . The method as claimed in  claim 1  wherein the diluted tailings are introduced into the diluent recovery vessel at a feed rate by weight, wherein the steam is introduced into the tailings pool at a steam addition rate by weight, and wherein the steam addition rate is between 5 percent and 30 percent of the feed rate. 
     
     
         15 . The method as claimed in  claim 14  wherein the steam addition rate is between 5 percent and 15 percent of the feed rate. 
     
     
         16 . The method as claimed in  claim 1  wherein the diluent recovery vessel has a lower end and an upper end and wherein the tailings pool is formed at the lower end of the diluent recovery vessel, further comprising providing a foam breaking device in the interior of the diluent recovery vessel between the tailings pool and the upper end of the diluent recovery vessel. 
     
     
         17 . The method as claimed in  claim 16  wherein the interior of the diluent recovery vessel defines a vessel axis and wherein providing the foam breaking device is comprised of rotating a foam breaker about a foam breaker axis which is parallel with the vessel axis. 
     
     
         18 . The method as claimed in  claim 17  wherein the foam breaker is comprised of a brush. 
     
     
         19 . The method as claimed in  claim 17  wherein mixing the diluted tailings is comprised of rotating a stirrer in the tailings pool about a stirrer axis which is parallel with the vessel axis. 
     
     
         20 . The method as claimed in  claim 19  wherein the foam breaker and the stirrer are both mounted on a stirring shaft and wherein the stirring shaft has a stirring shaft axis which is coincident with the foam breaker axis and the stirrer axis so that rotating the foam breaker and rotating the stirrer are both comprised of rotating the stirring shaft. 
     
     
         21 . The method as claimed in  claim 16 , wherein the interior of the diluent recovery vessel defines a vessel axis, wherein the tailings pool section has a tailings pool cross-sectional area transverse to the vessel axis in the interior of the diluent recovery vessel, wherein providing the foam breaking device is comprised of providing a foam breaking cross-sectional area transverse to the vessel axis in the interior of the diluent recovery vessel, and wherein the foam breaking cross-sectional area is larger than the tailings pool cross sectional area. 
     
     
         22 . The method as claimed in  claim 21  wherein the interior of the diluent recovery vessel is comprised of a vertical column. 
     
     
         23 . The method as claimed in  claim 1  wherein the hydrocarbon diluent is comprised of a naphthenic type diluent. 
     
     
         24 . The method as claimed in  claim 23  wherein an interior of the diluent recovery vessel has an absolute pressure of between 30 kPa and 120 kPa. 
     
     
         25 . The method as claimed in  claim 23  wherein an interior of the diluent recovery vessel has a temperature of between 60 degrees Celsius and 120 degrees Celsius. 
     
     
         26 . The method as claimed in  claim 1  wherein the hydrocarbon diluent is comprised of a paraffinic type diluent. 
     
     
         27 . The method as claimed in  claim 26  wherein an interior of the diluent recovery vessel has an absolute pressure of between 20 kPa and 110 kPa. 
     
     
         28 . The method as claimed in  claim 26  wherein an interior of the diluent recovery vessel has a temperature of between 40 degrees Celsius and 70 degrees Celsius. 
     
     
         29 . The method as claimed in  claim 1  wherein the diluted tailings are comprised of a coarse mineral material fraction of a froth treatment tailings. 
     
     
         30 . The method as claimed in  claim 29  wherein the hydrocarbon diluent is comprised of a naphthenic type diluent. 
     
     
         31 . The method as claimed in  claim 29  wherein the hydrocarbon diluent is comprised of a paraffinic type diluent. 
     
     
         32 . The method as claimed in  claim 29  wherein the residence time is between 1 minute and 20 minutes. 
     
     
         33 . The method as claimed in  claim 32  wherein the diluted tailings have a hydrocarbon diluent content and wherein the hydrocarbon diluent content is less than 3 percent by weight of the diluted tailings. 
     
     
         34 . The method as claimed in  claim 1  wherein the diluted tailings are comprised of a fine mineral material fraction of a froth treatment tailings. 
     
     
         35 . The method as claimed in  claim 34  wherein the hydrocarbon diluent is comprised of a naphthenic type diluent. 
     
     
         36 . The method as claimed in  claim 34  wherein the hydrocarbon diluent is comprised of a paraffinic type diluent. 
     
     
         37 . The method as claimed in  claim 34  wherein the residence time is between 1 minute and 50 minutes. 
     
     
         38 . The method as claimed in  claim 37  wherein the diluted tailings have a hydrocarbon diluent content and wherein the hydrocarbon diluent content is greater than 3 percent by weight of the diluted tailings. 
     
     
         39 . An apparatus for separating a diluted tailings comprising a hydrocarbon diluent into a recovered diluent component and a diluent recovered tailings component, wherein the diluted tailings are derived from a bitumen froth treatment process, the apparatus comprising:
 (a) a diluent recovery vessel having a lower end, an upper end, an interior, and a tailings pool section at the lower end of the interior of the diluent recovery vessel;   (b) a diluted tailings inlet for introducing the diluted tailings into the interior of the diluent recovery vessel;   (c) a recovered diluent component outlet at the upper end of the diluent recovery vessel for recovering the recovered diluent component from the diluent recovery vessel;   (d) a diluent recovered tailings component outlet at the lower end of the diluent recovery vessel for recovering the diluent recovered tailings component from the diluent recovery vessel;   (e) a steam distributor located in the tailings pool section of the diluent recovery vessel; and   (f) a mixing device associated with the tailings pool section of the diluent recovery vessel, for mixing the diluted tailings which form a tailings pool in the tailings pool section of the diluent recovery vessel.   
     
     
         40 . The apparatus as claimed in  claim 39  wherein the mixing device is comprised of a stirrer which is located in the tailings pool section of the diluent recovery vessel. 
     
     
         41 . The apparatus as claimed in  claim 39  wherein the mixing device is comprised of a recirculation circuit which is in communication with the tailings pool section of the diluent recovery vessel. 
     
     
         42 . The apparatus as claimed in  claim 41  wherein the recirculation circuit is comprised of a pump for passing the diluted tailings through the recirculation circuit. 
     
     
         43 . The apparatus as claimed in  claim 41  wherein the mixing device is further comprised of a stirrer which is located in the tailings pool section of the diluent recovery vessel. 
     
     
         44 . The apparatus as claimed in  claim 39 , further comprising a foam breaking device located in the interior of the diluent recovery vessel between the tailings pool section of the diluent recovery vessel and the upper end of the diluent recovery vessel. 
     
     
         45 . The apparatus as claimed in  claim 44  wherein the interior of the diluent recovery vessel defines a vessel axis, wherein the foam breaking device is comprised of a foam breaker, wherein the foam breaker has a foam breaker axis, wherein the foam breaker is rotatable about the foam breaker axis, and wherein the foam breaker axis is parallel with the vessel axis. 
     
     
         46 . The apparatus as claimed in  claim 45  wherein the foam breaker is comprised of a brush. 
     
     
         47 . The apparatus as claimed in  claim 45  wherein the mixing device is comprised of a stirrer which is located in the tailings pool section of the diluent recovery vessel. 
     
     
         48 . The apparatus as claimed in  claim 47  wherein the stirrer has a stirrer axis, wherein the stirrer is rotatable about the stirrer axis, and wherein the stirrer axis is parallel with the vessel axis. 
     
     
         49 . The apparatus as claimed in  claim 48  wherein the foam breaker and the stirrer are both mounted on a stirring shaft, wherein the stirring shaft has a stirring shaft axis which is coincident with the foam breaker axis and the stirrer axis, and wherein the stirring shaft is rotatable in order to rotate the foam breaker and the stirrer. 
     
     
         50 . The apparatus as claimed in  claim 44  wherein the interior of the diluent recovery vessel defines a vessel axis, wherein the tailings pool section has a tailings pool cross-sectional area transverse to the vessel axis in the interior of the diluent recovery vessel, wherein the foam breaking device is comprised of a foam breaking cross-sectional area transverse to the vessel axis in the interior of the diluent recovery vessel, and wherein the foam breaking cross-sectional area is larger than the tailings pool cross-sectional area. 
     
     
         51 . The apparatus as claimed in  claim 50  wherein the interior of the diluent recovery vessel is comprised of a vertical column. 
     
     
         52 . The apparatus as claimed in  claim 39  wherein the steam distributor is configured to introduce steam into the tailings pool section of the diluent recovery vessel in a direction toward the lower end of the diluent recovery vessel.