Bitumen extraction process
View Patent ↗A process for the extraction and recovery of bitumen from oil sands using deionized silicate solutions. Bitumen is recovered in a process comprising contacting a deionized silicate solution with an ore sand oil to produce a froth comprising bitumen and a tailings stream comprising water, sand and clay fines and optionally unrecovered bitumen. Preferably the tailings stream is dewatered and recovered water may be recycled to the extraction process.
1. A process for extracting bitumen from an oil sands ore, comprising (a) providing an aqueous slurry of an oil sands ore, and (b) contacting the slurry with a deionized silicate solution and optionally a caustic, to extract bitumen from the ore to produce i) a froth comprising bitumen, and ii) an aqueous tailings stream comprising sand and clay fines;
wherein the deionized silicate solution has a molar ratio of Si:M of at least 2.6, wherein M is an alkali metal and the deionized silicate solution has a S-value of 50% or greater.
2. A process according to claim 1 further comprising (c) dewatering the aqueous tailings stream.
3. A process of claim 2 further comprising adding an anionic polyacrylamide or an anionic polyacrylamide and a low molecular weight cationic organic polymer after step (b) and before step (c) to flocculate the aqueous tailings stream.
4. A process of claim 1 wherein air is added during the contacting step (b).
5. A process according to claim 1 wherein the temperature in step (b) is 25 to 90° C.
6. A process according to claim 1 wherein the deionized silicate solution is a deionized colloidal silica.
7. A process according to claim 1 further comprising, after step (b) a step (d) permitting separation of the aqueous tailings stream into a middlings and a coarse tailings.
8. A process according to claim 7 further comprising removing the froth from the aqueous tailings and contacting the froth with solvent to extract bitumen from the froth and to produce a froth treatment tailings.
9. A process according to claim 8 wherein the solvent is selected from the group consisting of paraffinic C 5 to C 8 n-alkanes, and naphthenic solvents.
10. A process according to claim 7 further comprising contacting the middlings with air to produce a second froth, a second middlings and a fine tailings, and permitting separation of the second froth and the fine tailings.
11. A process according to claim 10 further comprising contacting the second middlings with air to produce a third froth and a second fine tailings.
12. A process of claim 1 wherein the aqueous tailings stream comprises 1) a middlings stream of unrecovered bitumen and clay fines; and 2) a coarse tailings stream comprising sand and clay fines.
13. A process according to claim 1 further comprising, after step (b) and before step (c), step (d) permitting separation of the aqueous tailings stream into a middlings and a coarse tailings wherein step (c) comprises dewatering the middlings and coarse tailings separately.
14. A process according to claim 13 further comprising removing the froth from the aqueous tailings and contacting the froth with solvent to extract bitumen from the froth and to produce a froth treatment tailings.
15. A process according to claim 14 wherein the solvent is selected from the group consisting of paraffinic C 5 to C 8 n-alkanes, and naphthenic solvents.
16. A process according to claim 10 further comprising contacting the second middlings with air to produce a third froth and a second fine tailings.
17. A process according to claim 1 wherein the deionized silicate solution is prepared by contacting a solution of sodium silicate with a strong cation exchange resin.
18. A process according to claim 1 wherein the deionized silicate solution is prepared by contacting a solution of sodium silicate with a weak cation exchange resin.
19. A process according to claim 1 wherein the deionized silicate solution is prepared by removing alkali metal from a solution of alkali metal silicate using bipolar electrolysis.