Bitumen recovery from tar sands
First Claim
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1. A process for recovering bitumen from tar sands, the process comprising the step of:
- obtaining bitumen-containing tar sands;
pretreating the tar sands with a diluent so as to lower the viscosity of the bitumen such that the viscosity is in the range of from about 5 to about 20 poise at a digestion temperature of from about 40°
C. to about 70°
C.;
digesting the tar sand in a slightly basic solution at a temperature in the range of from about 40°
C. to about 70°
C. to disengage the bitumen from said particles in the tar sand;
mixing the tar sand during the digestion step so as to create a shear stress force field in the range of from about 20 to about 100 dynes per square centimeter; and
separating the tar sand into a bitumen-rich concentrate and tailings by flotation.
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Abstract
A process for recovering bitumen from tar sands wherein the tar sands are pretreated with a diluent, such as kerosene in the preferred embodiment, to lower the viscosity of the bitumen such that it is in the range of about 5 to about 20 poise at the digestion temperature. The tar sands are then digested at a temperature in the range of about 45° C. to about 60° C. and at a pH of about 7.8 to about 8.6. The tar sands are then transferred to a flotation cell where the bitumen-rich concentrate is separated from the sand.
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Citations
19 Claims
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1. A process for recovering bitumen from tar sands, the process comprising the step of:
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obtaining bitumen-containing tar sands; pretreating the tar sands with a diluent so as to lower the viscosity of the bitumen such that the viscosity is in the range of from about 5 to about 20 poise at a digestion temperature of from about 40°
C. to about 70°
C.;digesting the tar sand in a slightly basic solution at a temperature in the range of from about 40°
C. to about 70°
C. to disengage the bitumen from said particles in the tar sand;mixing the tar sand during the digestion step so as to create a shear stress force field in the range of from about 20 to about 100 dynes per square centimeter; and separating the tar sand into a bitumen-rich concentrate and tailings by flotation. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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14. A process for recovering bitumen from tar sands, the process comprising the steps of:
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obtaining a bitumen-containing tar sand; pretreating the tar sand with a diluent which is insoluble in water and which is readily dissolved by bitumen so as to lower the viscosity of the bitumen such that the viscosity is in the range of from about 5 to about 20 poise at 50°
C.;digesting the tar sand in a slightly basic solution at a temperature in the range of from about 45°
C. to about 60°
C. to disengage the bitumen from sand particles in the tar sand;mixing the tar sand during the digestion step so as to create a shear stress force field in the range of from about 20 to about 100 dynes per square centimeter; and separating the tar sand into a bitumen-rich concentrate and tailings by flotation. - View Dependent Claims (15, 16, 17, 18)
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19. A process for recovering bitumen from tar sands, the process comprising the steps of:
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obtaining a bitumen-containing tar sand; pretreating the tar sands with a solvent which is insoluble in water but is readily dissolved by bitumen so as to lower the viscosity of the bitumen such that the viscosity is in the range of from about 5.5 to about 20 poise at 50°
C.;digesting the tar sand at a solids concentration of about 75% in a solution having a pH in the range of from about 7.8 to about 8.6 and a temperature in the range of from about 45°
C. to about 60°
C.;mixing the tar sand during the digestion step so as to create a shear stress force field in the range of from about 20 to about 100 dynes per square centimeter; and separating the tar sand into a bitumen-rich concentrate and tailings in a flotation cell at a temperature in the range of from about 35°
C. to about 45°
C. and at a pH in the range of from about 6.8 to about 7.8.
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Specification