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US 4,676,889 AGranted
Solvent extraction process for recovering bitumen from tar sand
AssigneeChevron Research Company
InventorsC. Richard Hsieh, Roger K. Clifford
Life of this patent
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Abstract
Bitumen recovered from tar sand by direct solvent extraction followed by washing of the sand tailings with countercurrent solvent flow and a solvent/aqueous phase separation step to recover solvent and residual bitumen.
Claims15
A process for recovering bitumen from tar sand which comprises:
- (a) preparing a mixture containing divided tar sand and an organic solvent wherein the ratio of the solvent to the bitumen in the tar sand is at least 2 parts solvent to 1 part bitumen form a bitumen/solvent phase with a viscosity low enough to facilitate the physical separation of a significant portion of said bitumen/solvent phase from the mineral matrix of the tar sand;
- (b) separating by physical means at least a portion of the bitumen/solvent phase from the mineral matrix;
- (c) mixing the separated mineral matrix of step (b) with additional solvent in a washing stage to recover bitumen remaining with the mineral matrix;
- (d) introducing the recovered solvent/bitumen mixture from wash step (c) back into step (a);
- (e) recovering organic solvent from the mineral matrix of step (c) using an aqueous/organic solvent froth flotation phase separation wherein the majority of the mineral matrix remains with the aqueous phase;
- (f) recycling the solvent recovered from the phase separation of step (e) back to the washing step of (c);
- (g) separating bitumen from the bitumen/solvent phase of step (b);
- and
- (h) returning solvent collected from step (g) back to step (a).
6 more elements
Dependencies are inferred from the claim text.