Surfactant composition and method for treating bitumen froth

Abstract

The invention relates to a surfactant composition comprising an ionic liquid prepared from an unsubsituted or substituted primary, secondary or tertiary amine, or from an unsubstituted or substituted pyridine, amidine or guanidine with at least one fatty acid and/or resin acid. The invention also relates to a method for treating bitumen froth from a separation process, where bitumen is separated from mineral solids. The method comprises addition of said surfactant composition to the diluent and/or to the froth before phase separation.

Claims

1. A surfactant composition comprising at least one ionic liquid prepared from an unsubsituted or substituted primary, secondary or tertiary amine, or from an unsubstituted or substituted pyridine, amidine or guanidine with at least one fatty acid and/or resin acid.

2. The surfactant composition according to claim 1, wherein the composition comprises a mixture of fatty acids and/or resin acids.

3. The surfactant composition according to claim 1, wherein the fatty acid is selected from stearic acid or isostearic acid.

4. The surfactant composition according to claim 1, wherein the fatty acid originates from Kraft pulp process or from biodiesel production.

5. The surfactant composition according to claim 4, wherein the fatty acid is tall oil fatty acid.

6. The surfactant composition according to claim 1, wherein the substituted tertiary amine is choline.

7. The surfactant composition according to claim 1, wherein the substituted guanidine is tetramethylguanidine (TMG).

8. The surfactant composition according to claim 1, wherein the surfactant composition comprises two or more different ionic liquids.

9. Use of a surfactant composition according to claim 1 for separation of bitumen from an aqueous phase and mineral solids phase.

10. A method for treating bitumen froth from a separation process, where bitumen is separated from mineral solids, the method comprising obtaining bitumen froth that comprises bitumen, water and mineral solids, adding organic diluent, such as naphthenic or paraphenic solvent, to the froth, providing a phase separation between an organic phase, aqueous phase and solid phase, wherein a surfactant composition according to claim 1 is added to the diluent and/or to the froth before the phase separation in amount of less than 1500 ppm, preferably less than 1000 ppm.

11. The method according to claim 10, wherein the surfactant composition is added in amount of 5-1500 ppm, preferably 10-1000 ppm, more preferably 10-500 ppm.

12. The method according to claim 10, wherein bitumen is separated from mineral solids in a process that use oil sand, oil shale, oil contaminated sand or oil contaminated earth, tailing pond material and/or sand containing crude oil as raw material.

13. The method according to claim 10, wherein the obtained bitumen froth comprises 30-75 weight-% of bitumen, 15-35 weight-% of water and 5-20 weigh-% of mineral solids before the phase separation step.

14. A method according to claim 10, wherein the organic phase comprises 83-95 weight-% of bitumen, 0.1-0.5 weight-% of water and 0.0-0.5 weigh-% of mineral solids after the phase separation step.

15. A method according to claim 10, wherein the phase separation between the organic phase, aqueous phase and solid phase is performed by using centrifugation and/or gravity settling.

Description

EXPERIMENTAL

[0035] Preparation of Froth Samples

[0036] Froth sample was obtained from an industrial process. During the transport to the laboratory the sample was phase-separated. In the laboratory the froth sample was homogenized by using a 5 dm.sup.3 glass jacketed reactor equipped with stirrer over 3 hours under heating at 90? C. The froth sample comprised 10.6 weight-% of solid matter, 65.0 weight-% of bitumen and 24.4 weight-% of water.

[0037] Tested Ionic Liquids

[0038] Following ionic liquids were tested as surfactants:

[0039] N,N,N,N-tetramethylguanidinium stearate [TMG][Ster]

[0040] N,N,N,N-tetramethylguanidinium isostearate [TMG][iSter]

[0041] N,N,N,N-tetramethylguanidinium rosin [TMG][Ros]

[0042] Guanidine isostearate [Gd][iSter]

[0043] Choline isostearate [Ch][iSter]

[0044] Mixing of Froth with Surfactant/Toluene Solution and Centrifugation

[0045] Homogenized froth was removed from the glass jacketed reactor through the bottom valve into a glass beaker. 31 g of homogenized froth was transferred into each 50 ml Falcon centrifuge sample tubes while still hot. Approximately 8 g of surfactant/toluene solution was quickly added to maintain a surfactant/toluene:froth ratio of 1:3.9 or surfactant/toluene:bitumen ratio of 1:2.5. A blank sample comprising only toluene and froth and a reference sample comprising froth and a commercial surfactant comprising sodium dodecyl sulfate were also prepared at similar conditions.

[0046] Phase Separation and Bitumen Recovery

[0047] The Falcon centrifuge sample tubes were shaken vigorously by hand for a few minutes and then placed in a centrifuge to perform separation of the toluene-bitumen phase from the other froth constituents. Centrifugation was performed at 40? C. at 3000 rpm for 20 minutes. Solid material appeared in the bottom of the tube as a separate phase. The Falcon centrifuge sample tubes were allowed to rest for approximately 30 min. No visible phase separation of toluene-bitumen phase was observed. The liquid phase was removed to a second Falcon centrifuge sample tube where the phase separation is observed from bottom to top as follows: 0.1-2 ml of solid residue, 0.5-6.5 ml of clear liquid phase, 22-27 ml of toluene-bitumen phase.

[0048] Primary bitumen recovery is defined by measuring the volume of the bitumen-toluene phase in the second Falcon centrifuge sample tube by using the volumetric scale of the tube and using the known density of the bitumen sample in the calculations. Highly viscous bitumen remaining on top of the solid material layer in the first Falcon centrifuge sample tube used in the centrifugation was collected to form the secondary recovery of bitumen. Total bitumen recovery comprises both the primary bitumen recovery and the secondary bitumen recovery.

[0049] Samples for determining the water content by Karl Fischer analysis and solid matter content in toluene-bitumen phase were taken from the middle of the toluene-bitumen layer from the primary bitumen recovery.

[0050] Results

[0051] The bitumen recovery and water content results for [TMG][Ster] when used as surfactant are presented in FIG. 1. The results indicate that it is possible to provide 10.5% higher bitumen recovery with [TMG][Ster], used as 750 ppm concentration. At the same time, however, the water content in bitumen increases 2.56 fold. The optimum dosage was estimated to be somewhat lower, namely 500 ppm. This results a bitumen recovery which is 1.7% higher and a water content, which is 16% lower than the corresponding values for the reference sample.

[0052] The bitumen recovery and water content results for [TMG][iSter] when used as surfactant are presented in FIG. 2. The results indicate a higher bitumen recovery and relatively stable water content throughout the concentration series. The optimum dosage was estimated to be 500 ppm also for [TMG][iSter]. This concentration results a bitumen recovery which is 9.4% higher and a water content, which is only 8% higher than the corresponding values for the reference sample.

[0053] The bitumen recovery and water content results for [TMG][Ros] when used as surfactant are presented in FIG. 3. The optimum dosages were estimated to be drastically lower, either 137 ppm, which resulted 9.5% higher bitumen recovery with identical bitumen water content, or 274 ppm, which resulted identical bitumen recovery but 28% lower water content. This provides further degrees of freedom, depending whether the bitumen recovery or water content is of primary interest.

[0054] The bitumen recovery and water content results for [Gd][iSter] when used as surfactant are presented in FIG. 4. The optimum dosages were estimated to be either 240 ppm, which resulted a bitumen recovery which is 7.5% higher with similar water content, or 480 ppm, which resulted identical bitumen recovery but 48% lower water content than the corresponding value for the reference sample.

[0055] The bitumen recovery and water content results for [Ch][iSter] when used as surfactant are presented in FIG. 5. The optimum dosage was estimated to be 514 ppm, which resulted 52% lower water content than the corresponding value for the reference sample.

CONCLUSIONS

[0056] All ionic liquids comprising tetramethylguanidinium are able to provide higher bitumen recovery than the corresponding reference sample, but may cause increase in bitumen water content. One of the promising alternatives seem to be [TMG][Ros] which provides a positive response at significantly lower dosages. Furthermore [TMG][Ros] can provide significant improvement either in bitumen recovery, with increase by 9.5% units, or in water content with reduction of 28% units, depending on which parameter is more critical in the process. Results obtained with [Gd][iSter] and [Ch][iSter] are particularly interesting for operators who are suffering from high bitumen water content. These ionic liquids were able to provide a reduction of approximately 50% in water content, compared to corresponding value of the reference sample.

[0057] Even if the invention was described with reference to what at present seems to be the most practical and preferred embodiments, it is appreciated that the invention shall not be limited to the embodiments described above, but the invention is intended to cover also different modifications and equivalent technical solutions within the scope of the enclosed claims.