- 1) It can improve the recovery yield of bitumen and saleable synthetic crude oil equal to or above the present level;
- 2) It can improve thermodynamic efficiency and reduce the amount of heat required in bitumen extraction operations; and
- 3) It can reduce, or remove and eliminate, environmental impact.
- 4) The composition does not affect the total petroleum hydrocarbon (TPH) concentrations of the bitumen.

DESCRIPTION OF THE FIGURES

FIG. 1 shows Bitumen Recovery Units comparing the invention with prior art methods.

DETAILED DESCRIPTION OF THE INVENTION

The following description is provided to enable any person skilled in the art to make and use the invention and sets forth the best modes contemplated by the inventor of carrying out his invention. Various modifications, however, will remain readily apparent to those skilled in the art, since the general principles of the present invention have been defined herein specifically to provide an improved and environmentally safe composition for recovering bitumen from oil sands.

As used herein, the term “about” means “approximately,” and, in any event, may indicate as much as a 10% deviation from the number being modified.

Process

As explained in more detail below the current composition is directly useable in the current CHWE process. However, it somewhat modifies the way in which the process attains its results. The most apparent differences and advantages are the need for much lower amounts of energy because the water temperature is much lower and the use of environmentally safe additives so that the effluents from the process are harmless.

The process conceptually consists of four phases which are interdigitated into the CHWE process steps. In the first two phases, Phase I (extraction) and Phase II (separation)—an organic terpenoids solvent such as D-limonene is used to extract the organic compounds. Because the preferred terpenes are non-soluble in water a surfactant is used to decrease the surface tension of water to emulsify the terpene or even make it soluble both in water and in the organic (bitumen) phase. The large bitumen hydrocarbons are extracted by the terpene and surfactant thus freeing them from their bond to the sand. Also, when the terpene dissolves into the bitumen, it decreases both bitumen viscosity and density. The terpene will not extract/interact with all the organic compounds (particularly the low molecular weight and more hydrophilic compounds) in the bitumen. The alcohol and acetone extract and suspend the rest of the organic compound that are not extracted by the surfactant/terpene. Alcohol and acetone have a high affinity for small organic compounds therefore they continue to extract and separate the smaller organic hydrocarbons from the sand. The addition of the sodium carbonate pH builder acts to make the organic compounds more soluble in the organic phase because the amount of base added is not sufficient to saponify them as in the CHWE process. As a result the aqueous phase is not above pH 8 (i.e., fairly close to neutrality).

In the next two phases Phase III (blocking) and Phase IV (suspension) the alcohol and acetone as well as the pH builder keep the smaller molecules in suspension and keep them from reattaching themselves to the solids. The use of acetone and alcohol also decreases the boiling point needed separate the organics thus decreasing the heating requirements during the extraction and separation phase of the bitumen. The final product has a neutral pH and no toxic compounds have been added. The terpene, surfactant, alcohol and acetone are readily biodegradable.

Ingredients

As indicated, the present invention is a two component system for low temperature extraction of bitumen from oil sands. The first component is a solvent component and the second component is a pH building component. The solvent component comprises a monoterpene such as citral, citronellal, citronellol, limonene or linalool; the preferred terpene being the cyclic terpene D-limonene; a short chain alcohol, a short chain ketone and a non-ionic surfactant. The purpose of the solvent component is to dissolve into the bitumen and to loosen it from the sand and other solid material and help suspend it in an emulsion. The alcohol and ketone are relatively hydrophilic and interact with the hydrophilic moiety of the surfactant to emulsify and suspend the more organic hydrophobic components and/or to directly solvate them. Isopropyl and propyl alcohol are the preferred short chain alcohols although alcohols having between 2 and 5 carbons and ketones having 3-6 carbons (such as 2-butanone) are within the usable range. Acetone is the preferred ketone. The terpene is relatively hydrophobic and interacts/dissolves into the bitumen and interacts with the hydrophobic moiety of the surfactant.

Surfactants are amphiphilic organic compounds that have both hydrophobic and hydrophilic groups so that one end of the molecule is soluble in hydrophobic compounds such as bitumen and limonene while another part of the molecule is soluble in water and water miscible compounds such as isopropyl alcohol. As such they generally lower the surface tension of water and emulsify hydrophilic and hydrophobic compounds. In a typical oil in water emulsion (where hydrophilic particles are embedded in an aqueous milieu) The hydrophobic ends of the surfactant molecule are dissolved into the oil particles so that the surface of each particle is essentially covered by hydrophilic groups (the other ends of the surfactant molecules) which help the particles interact with and remain suspended in the water. Depending on the type of hydrophilic group present on the surfactant molecule, the surfactant may have a negative charge (an anionic surfactant), a positive charge (a cationic surfactant) or a neutral charge (a nonionic surfactant). The present invention generally employs anionic surfactants. Depending on the nature of the hydrophobic and hydrophilic groups a given surfactant may be generally hydrophilic or generally hydrophobic. This is known as the HLB or hydrophilic-lipophilic balance of the surfactant. The HLB scale runs from 0 to 20 with surfactants with an HLB number below about 10 being so hydrophobic that they are primarily lipid soluble while those with an HLB of greater than 10 are primarily water soluble. Surfactants having an HLB value in the range of about 7-11 act as emulsifiers that produce stable water in oil emulsions while those having an HLB value in the range of about 12-16 act as emulsifiers that produce stable oil in water emulsions. Surfactants having very high HLB values (e.g. 16-20) act as hydrotropes which are capable of solubilizing hydrophobic materials without forming micelles or small particles of the hydrophobic substance. It will be apparent that the preferred surfactants with be in the HLB range of 12-16 because bitumen is emulsified into water and then floated free to be recovered as a froth. Currently, ethoxylated/propoxylated alcohol-nonylphenol surfactants (such as TERGITOL NP-6 and NP-7 or NEXEO Surfactant 579 (Nexeo Solutions)) or ethoxylated/propoxylated branched alcohols (such as TRITO XL-80N) are preferred. A preferred single surfactant has an HLB of between 11 and 12. Addition of a quantity of lower HLB surfactant may encourage the bitumen particles to coalesce and allow separation particularly in a secondary recovery situation. Different surfactants can be combined to obtain an ideal HLB value. An ideal surfactant blend would create an HLB value between 12 and 16. In some situations addition of hydrotropic surfactant may aid in the initial separation of the bitumen from the solid mineral portion of the ore.

The preferred surfactants are nonionic although a small quantity of an anionic hydrotrope may be included in combination with the anionic surfactant(s). The surfactant may include one or more ethoxylated acetylenic alcohols, such as, for example, 2,5,8,11-tetramethyl-6-dodecyn-5,8-diol ethoxylate. In most cases, the ethoxysulfate analog of the ethoxylated can be substitute. Suitable non-ionic surfactants include, for example, DYNOL® surfactants such as DYNOL 604, or 607 (Air Products and Chemicals, Inc.); SURFYNOL® surfactants (Air Products and Chemicals, Inc.) such as SURFYNOL 420, 440, 465, and 485; TOMADOL® surfactants (Tomah Products, Inc.) such as TOMADOL 1-3, 1-5, 1-7, 1-9, 1-73B, 2.5, 23-1, 23-3, 23-5, 23-6.5, 25-3, 25-7, 25-9, 25-12, 45-7, 45-13; 91-6 and 91-8, TERGITOL® nonionic surfactants (Dow Chemical Company) such as TERGITOL MinFoam, L-61, L-64, L-81, L-101, NP-4, NP-6, NP-7, NP-8, NP-9, NP-11, NP-12, NP-13, NP-15, NP-30, and NP-40; TRITON® surfactants (Dow Chemical Company), such as TRITON X-15, X-35, X-45, X-100, X-114, X-165, X-305, X-405, X-207, BG and CA; NOVEC® Fluorosurfactant FC-4434 (3M Company); POLYFOX® AT-1118B (Omnova Solutions, Inc.); ZONYL® surfactants (DuPont) such as ZONYL 210, 225, 321, 8740, 8834L, 8857A, 8952, 9027, 9338, 9360, 9361, 9582, 9671, FS-300, FS-500, FS-610, 1033D, FSE, FSK, FSH, FSJ, FSA, and FSN-100; LUTENSOL® surfactants (BASF) such as LUTENSOL OP 30-70%, A 3 N, A 9 N, A 12 N, A 65 N, AO 3, AO 4, AO 8, AT 25, AT 55, CF 10 90, DNP 10, NP 4, NP-6, NP 9, NP 10, NP-50, NP-70-70%, NP-100, ON 40, ON 60, OP-10, TDA 3, TDA 6, TDA 9, TDA 10, XL 40, XL 50, XL 60, XL 69, XL 70, XL 79, XL 80, XL 89, XL 90, XL 99, XL 100, XL 140, XP 100, XP 140, XP 30 XP 40, XP 50, XP 60, XP 69, XP 70, XP 79, XP 80, XP 89, XP 90 and XP 99; MACOL® surfactants (BASF) such as MACOL 16, CSA 20 POLYETHER, LA 4, LA 12, LF 110 and LF 125A; MAPHOS polyphosphate ester nonionic surfactants (BASF) such as MAPHOS 58, 60A, 66H, 8135 and M-60; MAZON® 1651 surfactant (BASF); MAZOX® LDA Lauramine OXIDE (BASF); PLURAFAC® surfactants (BASF) such as PLURAFAC AO8A, B-26, B25-5, D25, LF 1200, LF 2210, LF 4030, LF 7000, RA-20, RA 30, RA 40, RCS 43, RCS 48, S205LF, S305LF, S505LF, SLF-18, SLF-18B-45, SLF 37, SL-22, SL-42, SL 62, SL 92, and L1220; PLURONIC® surfactants (BASF) such as PLURONIC 10R5, 17R2, 17R4, 25R2, 25R4, 31R1, F38, F68 LF, F68, F77, F87, F88, F98, F108, F108 NF, F127, F127 NF, F127NF 500BHT, L10, L31, L92, L101, L121, N-3, P65, P84, P85, P103, P105, P123; TETRONIC® surfactants (BASF) such as TETRONIC 304, 701, 901, 904, 908, 1107, 1301, 1304, 1307, 150R1. Mixtures of one of more of these surfactants can be used. Although nonionic surfactants are used almost exclusively, small quantities of ionic hydrotropic agents may be included. Suitable hydrotropic agents may include, for example, one or more of TRITON® products (Dow Chemical Company) such as TRITON H-66, H-55, QS-44 or XQS-20.

Soluble salts are added as pH builders to increase solubility of organic compounds in the organic phase and to help prevent reattachment of the bitumen. The preferred salts are sodium or potassium carbonate, silicate or hydroxide. The amount of pH builder added brings the extracted bitumen to near neutrality in pH. The “middlings” or effluent water is also near neutrality (e.g., below pH 8.0) unlike the high pH caustic effluents of the CHWE.

A laboratory test of a preferred embodiment of the present invention was made according to methods routinely used to test extraction of bitumen from oil sands. The method used is based on a paper “Batch Extraction Unit for Tar Sand Processing Studies by E. C. Sanford and F. A. Seyer of the Syncrude Canada Ltd., Research Department, Edmonton, Alberta, Canada which was a portion of the HENRY H. STORCH AWARD SYMPOSIUM presented in Miami Beach, Fla. in the fall of 1978. The method described in this paper defined the Bitumen Extraction Unit by providing a laboratory simulation of the commercial Clark extraction process. In this method a jacketed extraction cell (stainless steel pot) is maintained at a constant temperature (approximately 80° C. in the traditional process). The cell is square to facilitate slurrying and agitation by air or paddle stirring without need for added baffles. Air is added through the impeller (paddle) shaft, and the container is of sufficient height to provide a quiescent zone for froth accumulation. Impeller speed is controlled by a variable speed motor and tachometer. The cell has a valve at its bottom to remove tailings. In testing with the traditional hot water method, about 1.5 L of distilled water is heater to about 90° C. in a separate container. A quantity of oil sand is homogenized and an aliquot is subjected to a procedure to determine bitumen, solids and water content. A 500 g sample of the oil sand is weighed and 150 ml of the 90° C. water is added to the extraction cell. This water is stirred with the impeller in its lowest position until the water temperature is reduced to the jacket temperature (here 80° C.). The 500 g oil sand sample is added to the cell and the motor assembly and impeller are used to break up lumps with the impeller being left about ¾ of an inch above the bottom. The impeller is then set to 600 rpm and the airflow is adjusted to 465 cc/min and stirring is continued for 10 min. The airflow is stopped and 1 L of 80° C. water is added and stirring is continued for 10 min. Mixing is then stopped and the primary froth is skimmed off the top of the cell with a special spatula. The remaining material is mixed at 800 rpm with an airflow of about 232 cc/min for 5 min. The secondary froth is then collected. The froth samples are analyzed for bitumen, solid and water content. Finally solids and remaining water are drained from the cell; the cell is cleaned with solvent and the next sample is analyzed.

This same procedure (with slight modification described below) is carried out to test the inventive compositions except that test temperatures are lower than 80° C. As explained briefly above, the inventive composition consists of two parts, a solvent mixture and a pH builder. For the following tests a preferred embodiment of the solvent mixture was used and the pH builder was sodium carbonate as a 20% solution. For the tests the temperature was set to 35° C. For the “control” 500 g of tar sand (containing about 9.6% bitumen) was added to the cell along with 150 mL of 35° C. tap water. This mixture was stirred for 10 min (as described above). At that point a liter of 35° C. tap water was added and the stirring continued for another 10 min. The primary froth was collected and stirring (800 rpm) and air addition were started again for 5 min. Thereafter, the secondary froth was collected.

The solvent composition for this test contained D-limonene (15-25%), nonylphenol ethoxylated surfactant with HLB of 11-12 (25-35%), acetone (5-15%) and isopropyl alcohol (35-45%). For the treatment, the steps were the same except that 1 mL of the solvent component was added along with the 150 mL of water for the initial stirring. The 40 mL of pH builder (20% sodium carbonate) was added along with 960 mL of tap water for the stirring prior to primary froth collection. Following collection of the primary froth, air and stirring were restarted for 5 min. Then the secondary froth was allowed to float up and was collected.

A preferred solvent mixture for this use is 15%-25% D-limonene, 25-35% surfactant, 5%-15% acetone and 35%-45% isopropyl alcohol. A more preferred solvent mixture for this use is 18%-22% D-limonene, 28-32% surfactant, 8%-12% acetone and 38%-42% isopropyl alcohol. The remarkable thing is that only 1 mL of the solvent mixture was used to treat 500 g of oil sand ore in just over 1 L of water. The most useful range of the solvent mixture appears to be about 0.1 mL to about 5 mL per 100 g of ore. Larger amounts of the mixture can be used, of course. Because the minimum amount of surfactant is 35%, the formula cannot contain more than 65% mixed organic solvents. This comes out to 1.3 mL solvent per kilogram of ore or 1.3 L of solvent per metric ton of ore. This means that the actual concentration of solvents or surfactants released into the environment is extremely low. This also makes the cost of the solvent composition essentially insignificant. Even more important is that the small amounts of biodegradable solvents (and surfactants) that are added to the environment are essentially nontoxic. In terms of added pH builder about 16 g of sodium carbonate are used per kilogram of ore which equals about 1.6 kg of sodium carbonate per metric ton of ore—again a negligible quantity.

FIG. 1 shows the results of the inventive composition versus the control. Interestingly, the primary froth recovery was essentially identical for the control and the treatment, but the secondary froth recovery was dramatically higher for the treatment. Therefore, the total bitumen recovered for the control was 60% while that for the treatment was 79% which is essentially the recovery level produced by the traditional hot water system. Thus, the inventive process recovers the same amount of bitumen with a much lower energy burden to heat the water and without using sodium hydroxide and extremely high pH values. In fact, the middlings after the removal of froth and sand had a pH of only 8.6 whereas the control pH was 7.8. Quality measurements of the froths according to the methods developed by Sanford and Seyer showed that the qualities were comparable except that the treatment method produced froths having a lower level of solids (e.g., sand and clay particles). This is good because it reduces the amount of purification that the recovered bitumen must undergo. However, the primary froth from the treatment contained somewhat more water than the control. This appears to be related to the chain length of the surfactant (i.e., the hydrophilic-lipophilic (HLB) characteristic). Certain sand particle whose advancing water contact angles (θ_a) are in the range of 15-60° demonstrate a repulsive hydration force at relatively short separation distances. Appearance of the strong hydrophobic force is due to the likelihood that the double-chain cationic surface can create a higher hydrocarbon chain packing density than the single-chain cationic surfaces, thereby resulting in a significantly lower water inclusion in the froth while still rejecting solids. The ideal surfactant blend would create an HLB value between 12 and 16.

To demonstrate the innocuous characteristics of these ingredients a toxicology test was performed on the minnowPimephales promelas. The test material was a2% aqueous solution of the solvent composition. At the preferred use amounts (1 mL per liter) the effluent concentration would be 0.1% rather than 2%. It is assumed that the effluent would be further diluted before reaching the environment. The effluent was tested by treating the minnows with 750 mg/L of the effluent (a further dilution of over 1,000 fold). The diluted effluent showed no effect on the fish indicating that even without natural degradation of the active ingredients, simple dilution is sufficient to render the solvent composition innocuous. In actual practice, all of the solvent ingredients are biodegradable so that even less of the active ingredients will ever reach the environment. In addition, a certified microtox analysis was carried out usingVibrio flscherias a test organism. Again, a 2% dilution of the material was tested at a dilution of 10 g/L of test solution using 2% NaCl to achieve osmotic balance. A 50% dilution series (50 g/L down to 0.39 g/L) was carried out with a Model 50 benchtop unit following the procedures given in “Microtox Acute Toxicity Basic Test Procedures (1995) Microbics Corporation, Carlsbad, Calif.” and “Biological Test Method: Toxicity Test Using Luminescent Bacteria.” (November 1992).Report EPS 1/RM/24. Environment Canada. This produced an 15-min EC₅₀(mg/L) of 4.30 with a 95% confidence limit of 3.76-4.91 with a zinc sulfate reference toxicant. This translates to a Cumulative mean EC₅₀(±SD) for 20 tests of 4.02±0.91. This indicates extremely low toxicity.

The following claims are thus to be understood to include what is specifically illustrated and described above, what is conceptually equivalent, what can be obviously substituted and also what essentially incorporates the essential idea of the invention. Those skilled in the art will appreciate that various adaptations and modifications of the just-described preferred embodiment can be configured without departing from the scope of the invention. The illustrated embodiment has been set forth only for the purposes of example and that should not be taken as limiting the invention. Therefore, it is to be understood that, within the scope of the appended claims, the invention may be practiced other than as specifically described herein.