RECOVERY OF BITUMEN FROM OIL SANDS USING SONICATION

This invention relates to a process for the separation of bitumen from oil sands using sonication.

BACKGROUND

Bitumen is generally extracted from oil sands by hot water based extraction processes. In these processes, aggressive thermal and mechanical action is usually needed to liberate and separate the bitumen from the oil sands.

Water-based extraction processes generally involve the following steps:

Delivery of mined oil sand to crushers to reduce size of "oil sand lumps" for material handling purposes;

Mixing the crushed oil sand with warm or hot water to form a slurry of bitumen, mineral solids and water with addition of any chemicals believed to be necessary to enhance bitumen separation and recovery;

Transporting the aforementioned slurry to vessels where the bitumen is separated from the slurry;

Separating the aerated bitumen droplets in a primary separation vessel;

Recovering aerated bitumen droplets as bitumen froth; and

Recovering bitumen that was not recovered in the primary separation vessel (e.g. from the middlings stream

and the bottom of the primary separation vessel) in subsequent separation vessels. The middlings stream is a dilute suspension of water that contains mineral matter that has not settled to the bottom of the primary separation vessel and bitumen which did not float in the primary separation. The middlings are usually subjected to further flotation steps, for example, to recover additional bitumen.

Some oil sands (depending on, for example, the mineralogy of the original oil sand and the composition of the process water) form suspensions of high viscosity or suspensions exhibiting a high yield stress, which may inhibit bitumen flotation and therefore the recovery of bitumen.

For instance, it has been observed that clay containing bitumen-water suspensions may be sufficiently viscous or have a yield stress that impedes the flotation of aerated bitumen .

Two methods are generally employed to reduce the viscosity of an oil sand slurry. These are:

- Controlling the amount of fine mineral matter which is fed to the separation vessel (s); and

Addition of chemical process aids to enhance dispersion of very fine mineral particles that enter the separation vessel (s).

The relationship between middlings viscosity and recovery of bitumen in a commercial oil sands extraction process has been studied. (See Schramm, L. L. (1989), "The Influence of Suspension Viscosity on Bitumen Rise Velocity and Potential Recovery in the Hot Water Flotation Process for Oil Sands",

Journal of Canadian Petroleum Technology, 1989, 28(3), 73- 80. )

The water chemistry conditions under which the viscosity of slurries of Athabasca oil sands in water could be minimized for the purpose of increasing recovery of bitumen in an oil sands extraction process has also been studied. (See Wallace, D., Tipman, R., Komishke, B., Wallwork, V. and Perkins, E. (2004), "Fines/Water Interactions and Consequences of the Presence of Degraded Illite on Oil Sands Extractability", The Canadian Journal of Chemical Engineering, 2004, 82(4), 667-677.)

Also, studies suggest shear could be a contributing factor to the efficiency of a bitumen recovery process. For instance, an analysis of the bitumen recovery process indicated that the type of energy may be more important than the total amount of energy: see Sanford, E. C, "Processability of Athabasca Oil Sand: Interrelationship Between Oil Sand Fine Solids, Process Aids, Mechanical Energy and Oil Sand Age After Mining", The Canadian Journal of Chemical Engineering, 1983, 61, 554 - 567.

In suspensions of very fine solids isolated from the Athabasca oil sands, the application of shear was also shown to reduce the apparent viscosity of a suspension of clay in water. (See Chow, R., Zhou, J., and Wallace, D., "The Rheology of Oil Sands Slurries", Oil Sands 2006 Conference, Edmonton, AB, February 22 - 24, 2006.)

However, there remains a need for methods and devices that reduce the yield stress and/or reduce the viscosity of suspensions to allow for the flotation of bitumen in a bitumen-recovery process.

SUMMARY

According to an aspect of the present invention, there is provided a method for separating bitumen froth from an oil sand, the method comprising applying sonic energy to a bitumen-water slurry.

In one embodiment of the present invention, there is provided a method for separating bitumen froth from an oil sand, the method comprising adding water to an oil sand feed to form a slurry; conditioning the slurry; feeding the slurry to a separator; applying sonic energy to the slurry; and allowing the slurry to be separated into a bitumen froth and one or more heavier fractions.

BRIEF DESCRIPTION OF FIGURES

Figure 1 is a flow scheme of a bitumen extraction process according to an embodiment of the invention.

Figure 2 is a perspective drawing showing a manifold vertical array configuration of a sonic energy generating device according to one embodiment of the invention.

Figure 3 is a top view of a manifold vertical array configuration of a sonic energy generating device according to one embodiment of the invention.

Figure 4 is a schematic drawing showing the configuration and placement of slurry samples relative to a sonic generator .

Figure 5 is a schematic drawing of a test set-up to assess the effect of sonic energy on the viscosity of a laponite suspension .

Figure 6 is a graph showing a comparison of primary bitumen recovery when sonic energy is applied as compared with when no sonic energy is applied to ten oil sands samples.

Figure 7 is a graph showing a comparison of primary and secondary bitumen recovery when sonic energy is applied as compared with when no sonic energy is applied to ten oil sands samples.

Figure 8 is a graph showing a comparison of total bitumen recovery when sonic energy is applied as compared with when no sonic energy is applied to ten oil sands samples.

DESCRIPTION

There are a number of factors that may influence yield stress and/or viscosity of a suspension containing fine mineral solids.

For example, the concentration of fine solids, the mineralogy of the fine solids, the nature of the interaction between those fine solids to form either dispersed or coagulated suspensions of varying viscosity and the shear experienced by the suspension all influence the yield stress and/or viscosity of the suspension.

Hydrodynamics on the scale of a commercial separation vessel are quite complex. However, the flotation of aerated bitumen droplets and settling of coarse solids may be described approximately by Stokes' Law which defines the frictional force exerted on small spherical particles in a continuous viscous fluid. Stokes' Law takes the form:

u ₂ = (2*g/9)*r ₂ ² * (P ₂ -P ₁ ) / _ηi )

where U ₂ is the rise or sedimentation velocity, as the case may be, for a particle of radius r ₂ and of density p ₂ through a medium of density p _x and of viscosity ηi. The term, g, is the acceleration due to gravity.

In the case of bitumen flotation, because the density of the aerated bitumen, p ₂ , is less than the density of the middlings, pi, the value of u ₂ is positive, which corresponds to an upward movement or flotation of the aerated bitumen droplets .

For a process in which the slurry has a relatively constant residence time in the separation vessel, the greater the rise velocity, u ₂ , of the aerated bitumen droplets, the greater the likelihood of any single bitumen droplet reaching the surface of the separation vessel. Therefore, given a population of bitumen droplets in a dispersion, the greater the rise velocity, the greater the recovery of the bitumen droplets in the separation vessel.

Stokes' Law suggests that the following variables may be altered to increase the rise velocity of a bitumen droplet:

- Droplet size;

The density differential between the bitumen and the middlings phase through which the bitumen floats; and

The viscosity of the middlings phase. The concentration of solids in the middlings and the interactions among the fine particle fraction affects the viscosity of the middlings phase.

If the viscosity of the middlings phase can be reduced, the rise velocity for any aerated bitumen droplet should

increase proportionately and the likelihood of that aerated bitumen droplet reaching the surface of the separation vessel should also increase.

As noted above, there are a number of means by which viscosity of a suspension of mineral particles and bitumen droplets in water could be reduced. As further noted, in suspensions of very fine solids isolated from the Athabasca oil sands, the application of shear was shown to reduce the apparent viscosity of the suspension (Chow et al.) . Also, as noted above, the type of energy may be more important than the total amount of energy.

Thus the type of shearing inside the separator could be a contributing factor to the efficiency of a bitumen recovery process (Sanford E. C).

Also, the timing at which shear is applied to the oil sand suspension can play a role. Viscosity reduction by application of shear prior to the oil sand slurry being fed into a process unit may not be effective because the viscosity of the slurry increases almost instantaneously when shear is removed. Further, and in an example where the process unit is a separation vessel, the use of a mixer within the separation vessel may increase the shear, and thereby reduce the viscosity of the middlings; however, the large-scale mixing regime that might result from a mixer may interfere with the flotation of the bitumen in a commercial separation cell. Accordingly, for shear to be effective in improving bitumen flotation, it would have to be applied in a sufficient quantity during the bitumen flotation process to result in the desired degree of shearing, while not upsetting the hydrodynamic regime in the separation cell.

Sonic treatment involves the act of applying sonic energy to agitate particles in a sample. The effects of sonic waves are believed to differ from other forms of agitation such as mechanical agitation. Mechanical agitation, for example, by use of a conventional mixer or even by the discharge of the suspension from a pipe into a vessel, is generally much more vigorous and may result in a more drastic disruption of the flow patterns within a separation vessel.

It has been observed by the present inventors that the use of sonic energy may decrease the viscosity and/or yield stress of fluid suspensions of bitumen and may result in an improved separation of the bitumen from the solids fraction.

Devices used to introduce sonic energy into a bitumen suspension according to the present invention are not particularly limited. These generally include sonic generating devices, examples of which are sonic generators such as sonic probes or vibrating discs, for example. The acoustic frequency sonicator described in U.S. Patent No. 4,941,134 or U.S. Patent No. 5,005,773, may be used, for example. A person skilled in the art would be able to determine a suitable type of sonic generating device to be used, based on factors such as the type of separator, and the amplitude and frequency of agitation desired. These factors depend in turn on the nature of the oil sand, which is quite variable.

In one embodiment of the invention, a sonic generating device may be used in a bitumen extraction process, such as for example, a water-based extraction process.

Figure 1 shows an embodiment of the present invention used within a conventional bitumen extraction process. In an oil sands extraction process, oil sand feed (10) from a mining

operation, for example, may be fed to a crusher (30) via a truck (20) or similar device at an input end of the oil sands separation process. In the crusher (30), the oil sand lumps are reduced in size for material handling purposes and to allow for more rapid breakdown in the subsequent extraction process. The ore (38) may be conveyed via one or more conveyor belts (35). The discharge (50) from the conveyor belts (35) may be the inlet feed to a rotary breaker (60) or other device where water may be first added to the oil sand feed. The breaker (60) mixes the oil sands with a hot water stream (70) to produce a slurry mixture which passes through the openings in the walls of the breaker (60) or which may be transported from the breaker (60) into a pump box (100).

Rejects (80) from the breaker (60) such as the components of the oil sand feed (e.g. rocks, shale and hard lumps of oil sand) that are not sufficiently reduced in size in the breaker (60) to be fed into pipeline (90), may be removed. Chemical processing aids (95) may be added, for example, to the breaker (60), to the pump box (100), or to pipeline (90). Chemical processing aids may also be added to separation vessel (140), to flotation cells (180, 240), or to other parts of the process as would be understood by a person skilled in the art. Separation vessel (140) may be a separator, for example, while separation vessels (180, 240) may be flotation cells, for example. The slurry mixture from the pump box (100) may be fed to a pipeline (90) for simultaneous conditioning and transport to an array of bitumen separation vessels including vessels (140, 240) and (180) .

Pump (85) may provide the energy that transports the slurry to the separation vessels (140, 180, 240). There may be a series of pumps at various locations between the pump box (100) and the separation vessel (140).

The conditioned slurry (110) that is formed within the pipeline (90) may pass through pump (115) and is the inlet stream to a primary separation vessel, which may be, for example, a separator (140) . The types of separators that may be used at this stage would be known to a person skilled in the art. For example, conical shaped separation vessels or tanks and troughs of various configurations and dimensions can be used.

At the top of the separator (140), a bitumen froth (250) overflows the top of the separator into a collection device such as a launder (not shown) .

The bitumen froth (250) may be subjected to further processing steps, such as de-aeration in a steam de-aerator (260) and then may be sent via a pump (270) into a bitumen froth storage unit (280) .

In the separator (140), a large portion of the coarse solids can be separated from the bitumen and water mixture in the form of a concentrated slurry of solids in water. Some bitumen may remain in this concentrated slurry. The concentrated slurry may be removed through the bottom outlet (150) of the separator (140) and may be separated by a screen (160) into oversize particles (170), and to smaller particles (175), which may be sent to bitumen flotation cells (180) for additional bitumen recovery. The bitumen froth output (190) from the flotation cells (180) may be recycled into the conditioned slurry inlet stream (110) of

the separator (140). Alternatively, the bitumen froth (250) may be pumped directly to the steam de-aerator (260) . The bottom discharge (200) from the flotation cells (180), may be sent via one or more treatment units (210) to an external tailings facility (230) or other facility for treatment and reclamation of tailings. The output (215) from treatment unit (210) may be sent to a device for water recycling (300) which produces recycled water (305) and output (310) which may be sent to the tailings facility (230).

A middlings phase (225) from the separator (140) that comprises bitumen which did not float in the separator (140) and mineral particles which did not sink in the separator (140) may be subjected to further flotation of the bitumen in one or more flotation cells (240) . The flotation cells may be conventional flotation cells that are known to people skilled in the art or modifications thereof that allow for recovery of a bitumen froth. The bitumen froth output (246) from the flotation cells (240) may be recycled into the inlet stream (110) of the separator (140) . All or part of the bitumen froth (246) may be pumped directly to the steam de-aerator (260) .

The bottom discharge (245) containing water, mineral solids and unrecovered bitumen from the flotation cells (240) may be pumped into the bottom of the separator or otherwise combined with the stream from the bottom outlet (150) of the separator (140) .

When an embodiment such as Figure 1 is used, sonic energy may be applied to the contents of the separator (140), or potentially at other stages in the extraction process including the conditioning pipeline (90). The sonic energy

may be supplied via a sonic energy generating device (285), such as, for example a sonicator, located for example within or on the side of the separator (140), although addition of sonic energy at other locations within the process may be possible, provided that the device is able to transmit sonic energy into the contents of the separator. For example, one or more sonic energy generating devices may be directly in the separator where the device would cause the contents of the separator (e.g. the bitumen-water slurry) to vibrate. Alternatively, the sonic energy generating device may be placed on the outside of the separator, and the sonic energy may be transmitted to the contents of the separator through the wall of the separator. Sonic energy generating devices may also be present in or on one or more flotation cells (180, 240), or at other points within the extraction process .

It is believed that the application of sonic energy produces a shear that results in a decrease in the viscosity of the contents of the separator (140) resulting in an increase in the rise velocity of the aerated bitumen resulting in an increased recovery of bitumen froth (250). The sonic energy generating device includes electronic components. The electronic components of the device would ordinarily be located outside of the separator, while the portions of the device that transmit the sonic energy into the suspension may be located inside the separator so as to be in contact with the slurry. It is also possible for the sonic energy generating device to be located outside of the separator and transmit sonic energy through the walls of the separator. For example, the sonic generator may be a probe sonicator having an induction panel and an electronic portion for operating the probe sonicator. The electronic portion of

such a device may be located outside of a separator, while the probe and induction panel are within the separator.

Figure 2 shows an example of a configuration of a sonic energy generating device that may be used according to an embodiment of the invention. In Figure 2, an arrangement of multimodule "prong-type" sonic frequency sonicators that may be positioned inside a separator containing a slurry of mineral particles and bitumen is shown. The water and clay- bitumen separator (300) may have a top cylindrical portion (305) and a conical bottom portion (310) . The top portion (305) may be equipped with a manifold (320), for example. The manifold may have a sonic energy generating device comprising one or more sonicator prongs (330) which extend into the water-sand-clay-bitumen slurry (350). In an alternative embodiment, the bottom portion (310) of separator (300) may have one or more sonicator devices, which may be sonicator probes, for example.

Sonic energy from the sonicator prongs may increase the rise velocity of the aerated bitumen, while heavier fractions may separate out and be dispensed through outlet (335) at the bottom of separator (300). Figure 3 illustrates the top view of the arrangement shown in Figure 2.

EXAMPLES

Different configurations of sonic energy generating devices, test cells and materials were used to demonstrate that the application of sonic energy may decrease the yield stress and/or reduce the viscosity of suspensions of fine mineral matter to the extent that the rise velocity of low density particles is increased.

The tests were also designed to demonstrate that different configurations of sonic energy generating devices may be used to obtain the desired effect of decreased yield stress and/or viscosity reduction over a range of material compositions. The tests measured the desired effect through visual observation, measurement of viscosity and measurement of the flotation recovery efficiency of bitumen from oil sands in a bitumen recovery experiment .

Example 1: Flotation of Light Beads in a Coagulated

Suspension of Fine Mineral Matter from Athabasca Oil Sand

A slurry of mineral particles having an average size of less than 10 μm and spiked with greater than 1000 mg sodium/kilogram of slurry was produced from clay samples obtained from Alberta oil sands. Sodium was added to create similar conditions to those that may exist from time to time inside separation vessels during the production process. The fine mineral particles in a suspension of this water chemistry are known to coagulate, causing an increase in viscosity or yield stress, thereby inhibiting movement (i.e. flotation) of low density particles vertically through the coagulated suspension.

The test suspension of clay particles was opaque and dark, which affected the ability to visually observe the effect of sonic energy on the flotation of the low-density particles. Two features were incorporated into the design of the demonstration test to improve the ability to visually evaluate the effects of sonic energy.

First, G3500 Z-light ceramic microspheres, (manufactured by 3M, also referred to as 3M™ Hollow Ceramic Microspheres G- 3500) were used to simulate floatable bitumen particles.

These microspheres were of a specific gravity (700 kg/m ³ ) and size (median size of 130 μm and a d ₉₀ of 290 μ, where d ₉₀ is the size of a screen through which 90% of the microspheres would pass) similar to those of aerated bitumen particles. Once they float to the surface of the suspension, the Z- light microspheres are more easily distinguishable from the suspension as compared to the bitumen.

Second, the test configuration was adaptable to permit visualization of the effect of acoustics on flotation.

Observation of the separation/flotation of the microspheres was potentially difficult due to the colour-blending of the suspension and the microspheres, especially in test vessels of large volumes. Therefore, smaller test vessels were used in some experiments to better visualize the effect of acoustics on separation.

Figure 4 shows a schematic representation of the various configurations of the test vessels relative to the sonic energy generating device that was used. Four configurations are shown. The demonstration equipment consisted of a large, acrylic, clear-walled tank (400) that could be filled with either water or with the test suspension (410) . The tank had dimensions of 38 inches (length) by 8 inches (width) by 35.35inches (height) (95 cm X 20 cm X 88.38 cm). A prong- type of sonic generator (420) was immersed in either water or the test suspension.

In configuration 1, the tank (400) was filled with approximately 170 L of the test suspension and approximately 5% microspheres by weight. A single module "prong-type" sonic generator (420) was used to apply the sonic energy at a frequency in the range of 100 Hz to 500 Hz to the test

suspension. While some separation/flotation of the microspheres could be visualized in this configuration, the opacity of the suspension in the tank prevented clear visualization. However, a flotation effect was observed after approximately 10 seconds.

In configuration 2, the large tank (400) was filled with water. A small, closed, clear-walled, test vessel (430) filled with a mixture of the test suspension and microspheres (450) was immersed in the water in the large tank (400) immediately adjacent to the sonic generator. In configuration 3, the test vessel (430) was immersed in the water in the tank (400) but was separated from the sonic generator by distances up to several inches.

For each of the configurations 2 and 3, a single module

"prong-type" of sonic generator was used to apply the sonic energy in a frequency range of 100 Hz to 500 Hz to the test suspension either by direct contact of the sonic generator with the walls of the test vessel (430) or by transmittal of the sonic energy through the water in the large tank (400), through the walls of the test vessel (430) and into the test suspension inside the test vessel (430) .

In configuration 2, the test suspension was exposed to sonic energy by the means described previously for approximately 5 seconds. The microspheres floated toward the top of the test suspension during sonication, appearing at the surface within the 5-second test period.

In configuration 3, the test suspension was exposed to sonic energy by the means described previously. After 5 seconds, a smaller volume of microspheres was evident at the top of the test suspension than the volume observed in

configuration 2. It is believed that this was due to attenuation of the sonic energy over the distance between the generator and the test vessel (430).

Configuration 4 represents a control, where no sonication was applied to the vessel (430) containing the test suspension and microspheres (450). In this configuration, it took several hours to see visible separation of the microspheres from the suspension.

The above experiments demonstrated that sonic energy is able to reduce the yield stress or the viscosity of a clay suspension so that floatable material, such as bitumen, can float.

Example 2 : Sedimentation of Heavy Beads in a Transparent Suspension of Artificial Clays

A tank manufactured from Lexan™ was constructed with a metal structural frame to allow visual observation of tests performed. The tank was constructed to be long and narrow so as to allow testing at different distances from the sonic drive while limiting internal volume. The sonic drive system was mounted on a wall of the tank with a sealing system that allowed for the fitting of various induction panel shapes and sizes. The dimensions of the tank were 1 foot (height) by 1 foot (width) by 8 feet (length) (30 cm X 30 cm X 240 cm) . The tank also had a movable internal wall that allowed for the creation of a tank of smaller volume inside the large tank when testing at a distance of less than 8 feet (240 cm) was not necessary. In this manner, the length of the tank containing water or test suspensions could be reduced from 8 feet (240 cm) to less than 1 foot (30 cm) .

The drive system was variable in frequency and amplitude, unlike the device in Example 1 which operated at a fixed frequency and amplitude. A linear Bose™ fatigue analysis system was chosen as it can operate to a maximum amplitude of +1 mm and frequencies approaching 200 Hz.

The Bose system (ElectroForce™ 200N Test Branch) was linked to the tank through a hole in one end of the tank and made water tight with a seal. The drive shaft from the Bose drive was fitted with a bracket so that a variety of panels that could transmit sonic energy into the suspension of interest could be attached. The panels were not limited by shape or size except to be within the limits of the tank dimensions. The bulk of the work was done with a flat circular panel of 10.5 cm in diameter. A larger panel having a diameter of 15 cm was used to evaluate the effect on viscosity reduction.

The internal wall of the tank was located to create a small tank of dimensions 1 foot (height) by 1 foot (width) by 2 feet (length) (30 cm X 30 cm X 60 cm) within the large tank. A test suspension of laponite suspension having a viscosity of 170 cP at a shear rate of 5 s ^"1 and a viscosity of 17 cP at a shear rate of 200 s ^~l was added to the small tank.

Recipes for making such a suspension with this rheology can vary but a person skilled in the art would be able to determine suitable recipes to use. Laponite is an artificial clay that may be used to simulate clay suspensions and to investigate the movement of low density or high density particles through the suspension. Laponite suspensions have the advantages of being transparent over a wide range of concentrations, and of exhibiting a range of

yield stresses and viscosities simply by altering the pH and salt concentration in the suspensions.

In this test, glass beads that had been painted black and that were denser than the laponite suspension were dropped in the suspension just forward of the induction panel (i.e. the flat plate on the end of the reciprocating shaft) of the Bose system. The resulting drop of the beads was visually observed.

The beads were observed to drop at a velocity on the order of 1 cm/second until just above the top edge of the induction panel; at this point, the sedimentation velocity of the beads increased by a factor of approximately ten as they passed through the test suspension of laponite in front of the induction panel.

Deceleration occurred below the panel and just above the tank floor where the test beads were observed to slow to a similar rate to that observed at the beginning of the test. The test beads exhibited enhanced sedimentation with sonication as a result of the beads being heavier than the test suspension. However, Stokes' equation indicates that had low density beads been used, enhanced flotation would have been observed with sonication.

A second test was conducted wherein beads were placed in a line across the width of the tank at the surface of the suspension. Sonic energy was applied via the Bose generator and the pattern of beads falling was observed. Beads that were closest to the centerline of the panel were observed to fall as much as ten times faster than those at the edge of the small tank, outside the outer dimensions of the

induction panel. Conversely, beads that were placed close to the tank wall fell only slightly faster than when no sonic energy was applied, and slower than centrally located beads .

Example 3 : Direct Measurement of the Effect of Sonic Energy on the Reduction of Viscosity of a Laponite Suspension

To determine the effect of sonic energy on the viscosity of a laponite suspension, a test set-up as shown in Figure 5 was used. A straddle (520) was constructed to suspend a viscometer (500) over the top of the test tank (510) . The rotational measurement cylinder or "bob" of the viscometer (530) was then lowered into the suspension (505) while isolating the viscometer from vibration. A Bose sonic generator (540) comprising an induction panel (550) was used to provide sonic energy to the suspension as shown by double-headed arrow (560). The Bose sonic generator used was the same sonic generator as in Example 2.

A potential artifact that may interfere with the measurement of viscosity reduction is the transmission of sonic energy up the bob shaft to the sensor head. If this phenomenon exists, an apparent change in viscosity in response to application of sonic energy might be recorded by the instrument even though the viscosity of the test suspension was not affected by the sonic energy.

The possibility of transmission of sonic energy to the sensor head was investigated by measuring the viscosity of a Newtonian fluid (ethylene glycol) as a control with and without sonic induction. A Newtonian fluid is one in which viscosity is independent of shear in contrast to a non-

Newtonian fluid (such as a laponite suspension) where viscosity is a function of shear. When sonic energy was applied to a control experiment using ethylene glycol, there was no change in the viscosity reading provided by the viscometer. This demonstrated that the there was no sonic induction to the sensor head of the viscometer. Therefore, for non-Newtonian fluids, any measured changes in viscosity as a result of application of sonic energy could be attributed to the change in the viscosity of the non- Newtonian fluid itself.

The sonic energy applied to a test suspension can be characterized by frequency and amplitude. Both frequency and amplitude can be increased by increasing the voltage of the Bose sonic generator up to operational limits of amplitude and frequency for the generator. An initial attempt to optimize induction frequency was carried out by step-wise frequency change and setting the voltage to just below the auto shutdown point of the Bose system. For the specific design of the Bose system used in this experiment, a frequency of 27 Hz was determined to be the optimum frequency for reduction of viscosity of the laponite suspension. A frequency of this order also was subsequently confirmed for a test suspension of coagulated fine mineral matter isolated from Athabasca oil sand. Notwithstanding these measurements, other optimum combinations of frequency and amplitude as defined by required voltage to operate the sonic equipment may exist for other physical designs of sonic generation equipment.

To investigate the dissipation rate as distance from the induction source increases, the straddle viscometer was moved away from the induction panel at 4 inch (10 cm)

increments. The viscosity reduction effect was observable given a sonic frequency of 27 Hz out to a distance of 64 inches (160 cm) . Up to a distance of about 60 inches (150 cm) , there was a 25% reduction in viscosity as a result of sonication. At 68 inches (170 cm), no reduction in viscosity could be detected. This indicated that the effect of sonic energy was evident at considerable distances from the source. Such information is relevant to designing an appropriate array of sonic sources in a separation unit or vessel.

Other experiments indicated that the diameter of the induction panel on the Bose drive system also had an effect on the extent of viscosity reduction in the test suspension. This implied that optimum equipment designs for a commercial process should consider the physical configuration of the sonic source, and the frequency and amplitude of the drive system.

A similar test was used to measure the distance from the sonic source where the application of sonic energy could break the yield stress of a gelled test suspension of laponite. For the specific configuration of the Bose equipment used in this experiment, the sonic energy could break the yield stress up to a distance of 9 inches (22.5 cm) from the sonic source. While this experiment demonstrated that the sonic energy could be used for both viscosity reduction of a non-Newtonian fluid and breaking the yield stress of a gelled material, it is anticipated that far more power would be required to break yield stress than to reduce viscosity.

This example demonstrated that the effect of the sonic energy on enhanced flotation/sedimentation was related to a reduction in viscosity of the test suspension of clays.

Example 4 : Direct Measurement of Enhanced Recovery of Bitumen from Oil Sand Using a Sonic-Assisted Water Based Extraction Process

The effect of sonication on the recovery of bitumen from various oil sands was investigated using a test tank. The internal wall of the tank was located to create a small tank of dimensions 1 foot (height) by 1 foot (width) by 2 feet (length) (30 cm X 30 cm X 60 cm) within the large tank. The Bose sonic generator used in Examples 2 and 3 was mounted on the small tank in the same manner as in Examples 2 and 3.

A batch flotation cell for the determination of the recovery of bitumen from oil sand was constructed. The design of the cell followed that described by Bulmer, J. T. and Starr, J. in "Lab Scale Hot Water Extraction of Oil Sand", Syncrude Analytical Methods for Oil Sand and Bitumen Processing, Alberta Oil Sands Technology and Research Authority, Edmonton, Alberta, 1979.

The batch flotation cell described in Bulmer and Starr was a double walled cube-shaped cell constructed of steel with an internal dimension of 89 mm (height) x 89 mm (width) x 200 mm (length) . The double wall served to allow fluids to be circulated through the wall to control the temperature of the contents of the cell during the extraction test.

For the present experiment, a single-walled cell of the same dimensions was constructed with a square metal base of 89 mm

dimensions and metal posts approximately 200 mm long at each corner. The walls were constructed of polyethylene to allow the sonic waves to more readily penetrate the contents of the cell.

The internal wall of the tank was located to create a small tank of dimensions 1 foot (height) by 1 foot (width) by 2 feet (length) (30 cm X 30 cm X 60 cm) within the large tank. A platform was attached to the bottom of the small tank to allow attachment of the batch flotation cell. The small tank was filled with water and a laboratory circulator/heater was used to control the temperature of the water to 50 ⁰ C. Given the design of the platform, the batch flotation cell was immersed to a depth of approximately 190 mm in the small tank.

To determine the effect of sonic energy on the viscosity, the test cell was filled with a clay dispersion. When the vibrating disc was turned on and the polyethylene panels started to vibrate, the viscosity as measured by the rotating bob viscometer decreased.

Bitumen recovery experiments were carried out on ten oil sand samples that had been selected from various locations in the Shell Albian Muskeg River Mine. The experiments generally followed the standard procedure described by Bulmer and Starr which describes a laboratory method for measuring the amount of bitumen that can be recovered from oil sand in a water-based extraction process. In the present experiment, the test was conducted with water in the small tank at a temperature of 55°C (rather than at 82°C that is specified in the Bulmer and Starr method) . The lower

temperature more closely approximates current operating temperatures in commercial extraction circuits.

In the present experiment, three recovery steps were carried out (unlike in Bulmer and Starr where only two steps were carried out) .

The method in Bulmer and Starr resulted in a primary froth, and the proportion of bitumen in the test sample of oil sand recovered in the primary froth was referred to as "primary recovery". Furthermore, Bulmer and Starr described the subsequent collection of a secondary froth, and the proportion of bitumen recovered in the secondary froth was referred to as "secondary recovery".

Accordingly, and consistent with the terminology of Bulmer and Starr, in the present experiment, the proportion of bitumen in the test sample of oil sand that was recovered in the primary froth and the secondary froth is referred to as the "primary plus secondary recovery". In addition, in the present example, the method of collecting the secondary froth was subsequently repeated to produce a tertiary froth. The proportion of bitumen in the test sample of oil sand that was recovered in the primary, secondary and tertiary froth is referred to in this example as the "total recovery" .

In this experiment, the speed of the stirrer was reduced by a factor of two as compared to the speed that was used in Bulmer and Starr, namely, to 300 RPM. This step was taken so the system would not be swamped with mechanical energy, which might overwhelm the effect of the sonication. An oil sand slurry in any continuous bitumen recovery process, will

experience shear thinning due to mechanical mixing as well as sonic energy input. It is important, nonetheless, to recognize that the test cell used for this testing program does not scale hydrodynamically to any current commercial separation cell.

Ten separate oil sands were used to take into account the natural variability of the oil sands. The recoveries were measured, both when sonication was used, and when no sonication was applied. Sonic energy frequencies and levels were held constant for all tests.

It has been established in laboratory tests that the repeatability of a single batch extraction test is 3% absolute. This means that when comparing the recoveries of two tests on a single ore at different test conditions, the difference in recoveries must be greater than about 8% absolute to be viewed as being significant at the 95% level of confidence.

The data from the experiment (primary, primary plus secondary and total recoveries) are shown in Figures 6 to 8, with statistically significant differences between tests adding sonic energy and those not adding acoustic energy being marked by a star.

Figure 6 shows that in four cases, the primary recovery was statistically significantly higher with addition of sonic energy than without. Figure 7 shows that in two cases, the primary plus secondary recovery was statistically significantly higher with sonic energy than without. Figure 8 shows that in four cases, the total recovery was statistically significantly higher with sonic energy than

without. In no case was recovery without sonic energy statistically significantly better than with sonic energy (at the 95% level of confidence) .

Accordingly, with at least some oil sands, there is a benefit derived from the addition of sonic energy.

Although the foregoing invention has been described in some detail by way of illustration and example for purposes of clarity of understanding, it is readily apparent to those of ordinary skill in the art in light of the teachings of this invention that certain changes and modifications may be made thereto without departing from the spirit or scope of the appended claims.

The citation of any publication, patent or patent application is for its disclosure prior to the filing date and should not be construed as an admission that the present invention is not entitled to antedate such publication, patent or patent application by virtue of prior invention.

It must be noted that as used in the specification and the appended claims, the singular forms of "a", "an" and "the" include plural reference unless the context clearly indicates otherwise.

Unless defined otherwise all technical and scientific terms used herein have the same meaning as commonly understood to one of ordinary skill and the art to which this invention belongs .

Unless otherwise indicated, subject matter from all publications, patents and patent applications referenced herein is incorporated by reference.