FIELD OF THE ART

[0001] The present embodiments relate to processes recovering bitumen from oil sands ore wherein cement is used as a process aid.

BACKGROUND

[0002] Bituminous sands - colloquially known as oil sands (and sometimes referred to as tar sands) - are a type of unconventional petroleum deposit. The sands contain naturally occurring mixtures of sand, clays, water, and a dense and extremely viscous form of petroleum technically referred to as bitumen (or colloquially "tar" due to its similar appearance, odor, and color). Oil sands are found in large amounts in many countries throughout the world, but are found in extremely large quantities in Canada and Venezuela. Oil sand deposits in northern Alberta in Canada contain approximately 1.6 trillion barrels of bitumen, and production from oil sands mining operations is expected to reach 1.5 million barrels of bitumen per day by 2020.

[0003] Oil sands reserves have only recently been considered to be part of the world's oil reserves, as higher oil prices and new technology enable them to be profitably extracted and upgraded to usable products. They are often referred to as unconventional oil or crude bitumen, in order to distinguish the bitumen extracted from oil sands from the free- flowing hydrocarbon mixtures known as crude oil traditionally produced from oil wells.

[0004] Conventional crude oil is normally extracted from the ground by drilling oil wells into a petroleum reservoir, and allowing oil to flow into them under natural reservoir pressures, although artificial lift and techniques such as water flooding and gas injection are usually required to maintain production as reservoir pressure drops toward the end of a field's life. Because extra-heavy oil and bitumen flow very slowly, if at all, toward producing wells under normal reservoir conditions, the sands may be extracted by either strip mining or the oil made to flow into wells by in situ techniques which reduce the viscosity such as by injecting steam, solvents, and/or hot air into the sands. These processes can use more water and require larger amounts of energy than conventional oil extraction, although many conventional oil fields also require large amounts of water and energy to achieve suitable production rates.

[0005] The original process for extraction of bitumen from the sands was developed by Dr. Karl Clark, working with Alberta Research Council in the 1920s. Today, the producers doing surface mining use a variation of the Clark Hot Water Extraction (CHWE) process. In this process, the ores are mined using open-pit mining technology. The mined ore is then crushed for size reduction. Hot water at 40-80°C is added to the ore and the formed slurry is conditioned and transported, for example using a piping system called hydrotransport line, to the extraction unit, for example to a primary separation vessel (PSV) where bitumen may be recovered by flotation as bitumen froth. The hydrotransport line may be configured to condition the oil sand while moving it to the extraction. The water used for hydrotransport is generally cooler(but still heated) than in the tumblers or conditioning drums.

[0006] The displacement and liberation of bitumen from the sands is achieved by wetting the surface of the sand grains with an aqueous solution containing a caustic wetting agent, such as sodium hydroxide, sodium carbonate, sodium silicate or calcium hydroxide. The resulting strong surface hydration forces operative at the surface of the sand particles give rise to the displacement of the bitumen by the aqueous phase. Once the bitumen has been displaced and the sand grains are free, the phases can be separated by froth flotation based on the natural hydrophobicity exhibited by the free bituminous droplets at moderate pH values (Hot water extraction of bitumen from Utah tar sands, Sepulveda et al. S. B. Radding, ed., Symposium on Oil Shale, Tar Sand, and Related Material - Production and Utilization of Synfuels: Preprints of Papers Presented at San Francisco, California, August 29 - September 3, 1976; vol. 21, no. 6, pp. 1 10-122 (1976)).

[0007] The recovered bitumen froth generally consists of about 60% bitumen, 30% water and 10% solids by weight. The recovered bitumen froth may be cleaned to reject the contained solids and water to meet the requirement of downstream upgrading processes. Depending on the bitumen content in the ore, between 90 and 100% of the bitumen can be recovered using modern hot water extraction techniques.

[0008] The amount of bitumen and quality of the froth may be dependent, for example, on the bitumen's ability to separate from sand grains and attach to air. It has been observed that when the pH of the process is increased to between 8-10, organic acids in the bitumen may be neutralized into natural surfactants. These surfactants improve bitumen-air attachment by lowering interfacial tension and they separate the bitumen from sand grains by increasing interfacial charges. This improves the amount of bitumen which is recovered in the primary flotation process and helps to reduce the amount of solid particulate which is included in the froth.

[0009] Sodium hydroxide is used commercially to provide the alkaline environment for the CHWE process. Other inorganic bases such as sodium silicate, sodium carbonate, ammonia, and sodium tripolyphosphate have been evaluated and found to be inferior to NaOH, because, for example, they require a higher concentration or were unable to provide the same level of recovery as NaOH. Several other chemical classes of reagents have been proposed to improve bitumen recovery and froth quality. These include surfactants, flocculants, polymeric dispersants, and organic solvents. These approaches have been found to provide varying levels of success in laboratory tests, but generally NaOH is still the most economical choice and therefore the commercially preferred process aid. Sodium hydroxide is, however, extremely corrosive and highly reactive, requiring specialized engineering controls, protective equipment and personal hygiene measures. Use of NaOH also may result in accumulation of sodium ions in recycled water, which can cause dispersion of higher clays and can produce tailings with poor geotechnical properties that turn into mature fine tailings. This is especially true for low grade and oxidized ores, which present the greatest challenges in bitumen recovery and produce the major portion of fine tailings.

[0010] US Patent Publication No. 2008/0223757 discloses a method for enhancing the efficiency of bitumen recovery from oil sands ore, said method comprising the step of mixing lime into an oil sands ore-water slurry in association with a slurry-based bitumen extraction process.

[0011] The description herein of certain advantages and disadvantages of known methods and compositions is not intended to limit the scope of the present disclosure. Indeed, the present embodiments may include some or all of the features described above without suffering from the same disadvantages.

BRIEF SUMMARY

[0012] Disclosed herein are processes for recovering bitumen from oil sands ore wherein cement is used as a process aid. In one aspect, a process is provided for recovering bitumen from oil sands ore, comprising: (i) adding cement to an oil sands ore-water slurry; and (ii) liberating bitumen. In another aspect, a process is provided for extracting bitumen from an oil sand ore, comprising: (i) mixing oil sands ore with water or an aqueous solution to form a slurry; (ii) aerating the slurry to form a froth containing bitumen within the slurry; (iii) separating the froth from the slurry; (iv) adding cement to the slurry prior to or during one or more of the preceding steps; and (v) liberating bitumen from the froth. In particular embodiments, the cement comprises one or more types of hydraulic cements, such as Portland cement.

BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 shows the bitumen recovery data as a function of time for low grade ore sample LG2 treated by sodium hydroxide and API class A cement (Cem A).

[0014] Figure 2 shows the bitumen recovery rate as a function of added API class A cement.

[0015] Figure 3 shows the bitumen recovery as a function of time for low grade ore sample LG3 when pH of water was adjusted to 8.5 and 10.0 using sodium hydroxide and API class A cement. DETAILED DESCRIPTION

[0016] Disclosed herein are processes for enhancing recovery of bitumen from oil sands ore. In particular, exemplary processes for the recovery of bitumen from oil sands ore involve a water-based extraction process whereby a cement is added to a oil sands ore-water slurry. The water-based extraction process of oil sands refers to any known extraction process for producing aqueous tailings, including but not limited to the Clark Hot Water Extraction (CHWE) process, a hot water flotation process, or the like.

[0017] It has been discovered that cement, such as a hydraulic cement like Portland cement, can be used to adjust alkalinity of the oil sand ore-water slurry to enhance the efficiency of bitumen recovery in an extraction process. Cement can be an economical process aid, particularly compared to sodium hydroxide. In addition, the handling and storage of cement is relatively safe when compared to corrosive sodium hydroxide. The cement, as used herein, may make fine and ultrafine solids more hydrophilic and agglomerated. It also may facilitate bitumen-air bubble attachment and thus improve bitumen flotation.

[0018] Cement

[0019] In exemplary embodiments, the cement process aid may be any of a variety of cements and pozzalanic materials. In one embodiment, the cement contains one or more hydraulic cements. Exemplary hydraulic cements include Portland cement, Portland-based cement, pozzolana cement, gypsum cement, high alumina cement, slag cement, silica cement, kiln dust or mixtures thereof. Exemplary Portland cements may be those classified as class A, C, H and G cements according to American Petroleum Institute (API) specification for materials and testing for well cements. They can also be classified by ASTM CI 50 or EN 197 in classes of I, II, III, IV and V. In one embodiment, the cement is a hydraulic cement that comprises calcium, aluminum, silicon, oxygen and/or sulfur which may set and harden by reaction with water. In one embodiment the cement is an alkaline cement. In a particular embodiment, the cement comprises a mixture of two or more hydraulic cements..

[0020] In one embodiment, the cement comprises one or more types of Portland cement. Portland cement is the most common type of cementitious material used around the world. It consists mainly of calcium silicates and aluminates and some iron-containing phases. When mixed with water, Portland cement undergoes various hydration reactions resulting in raised pH as well as generation of new species including calcium silicate hydrates (CSHs). CSH may bind strongly to other mineral grains, resulting in a setting process.

[0021] Portland cement (also referred to as Ordinary Portland Cement or OPC) is a basic ingredient of concrete, mortar, stucco and most non-specialty grout. Portland cement is a mixture that results from the calcination of natural materials such as limestone, clay, sand and/or shale. In particular, Portland cement comprises a mixture of calcium silicates, including CasSiOs and Ca ₂ Si0 ₄ , which result from the calcination of limestone (CaCOs) and silica (S1O2). This mixture is known as cement clinker. In order to achieve the desired setting qualities in the finished product, calcium sulfate (about 2-8%, most typically about 5%), usually in the form of gypsum or anhydrite, is added to the clinker and the mixture is finely ground to form the finished cement powder. For example, a typical bulk chemical composition of Portland cement is about 61 to about 67 wt% calcium oxide (CaO), about 12 to about 23 wt% silicon oxide (S1O ₂ ), about 2.5 to about 6 wt% aluminum oxide (AI ₂ O ₃ ), about 0 about 6 wt% ferric oxide (Fe ₂ 0s) and about 1.5 about 4.5 wt% sulfate. The properties of Portland Cement can be characterized by the mineralogical composition of the clinker. Major clinker phases present in Portland cements include: Alite (3CaO.Si0 ₂ ), Belite (2CaO.Si0 ₂ ), Aluminate (3Cao.Al ₂ 0 ₃ ) and Ferrite (4CaO. Al ₂ 0 ₃ .Fe20 ₃ ).

[0022] In an exemplary embodiment, the cement is a fine powder mixture which contains more than 90% Portland cement clinker, calcium sulfate and up to 5% minor constituents (see European Standard EN 197.1).

[0023] During the preparation of the cement, a grinding process may be controlled to obtain a powder with a broad particle size range, in which typically 15% by mass consists of particles below 5 μιη diameter, and 5% of particles above 45 μιη. The measure of particle fineness usually used is the "specific surface area", which is the total particle surface area of a unit mass of cement. The rate of initial reaction (up to 24 hours) of the cement on addition of water is directly proportional to the specific surface area. Typical values are 320-380 m ² -kg ^_1 for general purpose cements, and 450-650 m ² -kg ^l for "rapid hardening" cements.

[0024] Bitumen Recovery/Extraction Processes

[0025] In an exemplary embodiment, a process for enhancing the efficiency of bitumen recovery from oil sands ore comprises adding water and cement to the oil sands ore which contains bitumen.

[0026] In one embodiment, a process for recovering bitumen from oil sands ore includes: (i) adding cement to an oil sands ore-water slurry; and (ii) liberating bitumen.

[0027] In another embodiment, a process for extracting bitumen from an oil sand ore includes: (i) mixing oil sands ore with water or an aqueous solution to form a slurry; (ii) aerating or conditioning the slurry to form a froth containing bitumen within the slurry; (iii) separating the froth from the slurry; (iv) adding cement to the slurry prior to or during one or more of the preceding steps; and (v) liberating bitumen from the froth.

[0028] In exemplary embodiments, the cement process aid may be added in any mixing, conditioning, or separation step in the bitumen recovery process. In view of the embodiments described herein, it will be understood that the cement process aid could be added at other points in the bitumen recovery/extraction process as necessary or desired.

[0029] In one embodiment, the cement may be added to the oil sand ore-water slurry during any point before or during the mixing stage. In exemplary embodiments, mixing of the ore-water slurry may be achieved by any known process or apparatus. For example, after the oil sands ores have been mined and crushed, the oil sands ores may be transported by conveyor to a slurry preparation plant, where hot water is added to make the oil sand ore-water slurry. In one embodiment, the oil sands ore may be low grade ore. In one embodiment, the oil sands ore may be high grade ore. In exemplary embodiments, the temperature of the water and/or the slurry may be any temperature as necessary or desired. In an exemplary embodiment, the temperature of the water and/or the slurry may be elevated to provide an effective amount of heat to the slurry to substantially release the bitumen from sand surface. In one embodiment, the water or aqueous solution used in the process may be between at a temperature of about 0°C to about 100°C; 0°C to about 90°C; about 20°C to about 90°C; about 40°C to about 90°C; or about 40°C to about 60°C. In exemplary embodiments, depending, for example, on the temperature of the water, and/or the availability of thermal energy in the process, the temperature of the slurry may be elevated to and/or maintained at about 40° C to about 60° C. In the exemplary embodiments, the cement may be added before or during any of the mixing and conditioning stages described above, or their respective equivalents.

[0030] In one embodiment, the cement may be added to the oil sand ore-water slurry during any point before or during a conditioning stage. Conditioning of the slurry, as described herein, may include further mixing or churning of the slurry, aeration of the slurry to form a froth, breaking of lumps in the slurry into smaller lumps, liberation of bitumen from sand grains, breaking of bitumen into smaller droplets, attaching liberated bitumen droplets to air bubbles, mixing the slurry with optional additives and other process aids, or the like. Generally, the effect of the conditioning stage is to enhance or maximize the liberation of bitumen from the sand grains and separation of bitumen or the froth containing bitumen from the slurry. Conditioning of the slurry may be achieved by any means known in the art and is not limited to the embodiments described herein.

[0031] In exemplary embodiments, after the slurry has been prepared and mixed, the ore-water slurry may be conditioned by any known process or apparatus. For example, after the slurry is formed, the slurry may be transported through a slurry hydrotransport pipeline, which may be used to condition the slurry. In the slurry hydrotransport pipeline, the hydrodynamic forces from speed of the slurry may liberate bitumen from the sand grains, break the liberated bitumen into smaller droplets, and promote attachment of the liberated bitumen droplets to entrained air bubbles. In exemplary embodiments, the size, shape, configuration, and length of the hydrotransport pipeline may be predetermined to provide any necessary or desired results. For example, the length of the hydrotransport pipeline may be determined, at least in part, on the processing plant location, the slurry temperature, the initial lump size, or other conditions that may affect the conditioning of the slurry. In some embodiments, the hydrotransport pipeline may be up to about 5 kilometers. The speed of the slurry through the hydrotransport pipeline may be predetermined to provide any necessary or desired result. For example, in an exemplary process, the slurry is transported through the pipeline at about 3 to about 5 meters per second. In the exemplary embodiments, the cement may be added before or during any of the mixing and conditioning stages described above, or their respective equivalents.

[0032] Aerating the slurry (or a derivative of the slurry) may be achieved by any means know in the art. In exemplary embodiments, aerating the slurry promotes the formation of froth and may be achieved, for example by mixing or churning the slurry in a mixing or transport vessel or apparatus, such as the transport of the slurry in a slurry hydrotransport pipeline. In some embodiments, the slurry or a derivative thereof may be aerated, for example, by sparging the slurry or derivative thereof in a vessel or apparatus (e.g., during the secondary separation process, described below). In one embodiment, the cement may be added to the oil sand ore-water slurry (or any derivative thereof) before or during any extraction process. As used herein, an "extraction" process may include any process step or stage that furthers the liberation, separation, or isolation of bitumen from the other components of the oil-water slurry or its derivatives.

[0033] In one embodiment, the cement may be added to the oil sand ore-water slurry (or any derivative thereof) before or during a primary separation process. As referred to herein, the "primary separation process" is the first separation of bitumen froth from solids after the oil sands ore-water slurry is formed and conditioned. In exemplary embodiments, primary separation of the bitumen froth from the solids may be accomplished by any known process or apparatus. For example, at the end of the slurry hydrotransport pipeline, the conditioned slurry may be discharged to one or more large stationary particle separation cells (PSC) or vessels. In the PSC, the aerated bitumen may float through the slurry upwards to the top of the cell where it may overflow, and be collected as primary bitumen froth. Within the PSC, the coarse solids may settle, forming a dense slurry at the bottom of the PSC which can be removed from the bottom of the PSC as "tailings" stream. Within the PSC, fine solids with some un-aerated fugitive fine bitumen droplets may remain suspended in the slurry. This low-density slurry may be removed from the middle of the separation cell as a "middlings" stream. In various embodiments, the cement process aid may be added before or during any of the primary separation stages described herein, or their respective equivalents. For example, the cement process aid may be added to the oil sand ore-water slurry in the PSC.

[0034] In exemplary embodiments, one or more of the streams from the primary separation processes may optionally undergo further processing to further the bitumen separation and isolation from the other components of the streams. These processes are referred to as "secondary separation processes." In exemplary embodiments, the cement may be added to the slurry or any derivative thereof in a secondary separation process. For example, the middlings stream may be further processed using flotation technology to enhance bitumen-air attachment. An exemplary flotation technology may be, for example, mechanical flotation process or a flotation column in which air is added to enhance bitumen- air attachment. In this flotation process, middlings may be subjected to vigorous agitation and aeration, and the aerated fine bitumen droplets may be recovered as secondary bitumen froth. The secondary bitumen froth may be returned to the PSC for further cleaning or sent with the primary bitumen froth from PSC to a subsequent bitumen froth cleaning stage. In exemplary embodiments, the tailings stream from the PSC may be further processed, for example, in a tailings oil recovery (TOR) unit. The TOR may include a secondary separation cell or a flotation cells for further recovery of bitumen from the tailing stream. In the secondary separation processes, additional air or water may be added to the process streams to further enhance the separation or isolation of bitumen. In the embodiments, cement may be added to the slurry or process streams thereof to further enhance the separation or isolation of bitumen from these streams.

[0035] In exemplary embodiments, the streams from separation processes may optionally undergo additional processing to further the bitumen separation and isolation. For example, the primary separation process and/or the secondary separation process, or any of the steps related thereto may be repeated in order to achieve the necessary or desired result. In the exemplary embodiments, the cement process aid may be used in these additional processing steps to further the bitumen separation and isolation.

[0036] In certain embodiments, the cement can be used to replace some or all of the sodium hydroxide or other process aid chemicals in a process for recovering bitumen from oil sands ore. In one embodiment, the process does not comprise the addition of any sodium hydroxide or other process aid chemicals other than cement.

[0037] In the exemplary embodiments, the cement material may be added to the oil sands slurries as a dry powder or as a suspension in water.

[0038] In exemplary embodiments, the cement may be added to the oil sands ore- water slurry (or any process streams derived therefrom) in any amount to provide a necessary or desired result. For example, the dosage of cement may be the amount effective to provide the maximum yield of bitumen at that point in the process. In exemplary embodiments the cement may be added in a broad range of cement dosages without adversely impacting bitumen extraction or release water chemistry. In exemplary embodiments, the cement dosage may be that which is effective to reduce the attraction between clay particles and bitumen, thereby promoting the detachment of clay particles from bitumen droplets in an oil sands ore-water slurry. In exemplary embodiments, the dosage of cement process aid is any amount sufficient to raise the pH of the slurry or stream to about 6 to about 12, or about 8 to about 1 1, or about 8.5 to about 10.

[0039] In one embodiment, the dosage of cement added to the oil sands ore-water slurry or process streams derived therefrom is in the range of about 10 to about 10000 grams cement per dry ton (g/t) of ore (e.g., for the slurry) or of dry suspended solids (e.g., for other process streams). In some embodiments, the dosage is from about 100 to about 5000 g/t, about 100 to about 2000 g/t, about 50 to about 1700 g/t, about 100 to about 1600 g/t, about 500 to about 1150 g/t, or about 500 to about 1000 g/t. In one embodiment, the dosage of cement is about 300 g/t, about 350 g/t, about 400 g/t, about 450 g/t, about 500 g/t, about 550 g/t, about 600 g/t, about 650 g/t, about 700 g/t, about 750 g/t, about 800 g/t, about 850 g/t, about 900 g/t, about 950 g/t, about 1000 g/t, about 1050 g/t, about 1100 g/t, about 1 150 g/t, about 1200 g/t, about 1250 g/t, about 1300 g/t, about 1350 g/t, about 1400 g/t, about 1450 g/t, about 1500 g/t, about 1550 g/t, or about 1600 g/t.

[0040] In one embodiment, after addition of the cement, the cement is permitted to remain in contact with the oil sands ore-water slurry (or process streams derived therefrom) for a predetermined amount of time prior to separation of the bitumen. In some embodiments, the cement remains in contact with the oil-water slurry or a process stream for about 10 minutes to about 180 minutes, about 15 minutes to about 120 minutes, about 20 minutes to about 90 minutes, or about 20 minutes to about 60 minutes prior to the separation of the bitumen.

[0041] In certain embodiments, the processes may recover at least about 5%, about 10%, about 20%, about 30%, about 40%, or about 50% more bitumen than comparable processes using sodium hydroxide or lime.

[0042] In one embodiment, at least about 60%, about 65%, about 70%, about 75%, about 80%, about 85%, about 90%, about 95% of the total organic compounds or bitumen are extracted in the primary and secondary separation steps of the processes described herein.

[0043] In any of the foregoing embodiments, the slurry (or process streams derived therefrom) may further include any additive or other process aid, such as a surfactant, an anti- foaming agent, a polymer, a flocculent, a mineral oil or a mixture thereof. In one embodiment, the additives are in an amount of 0.01 to 10 weight percent based on the total weight of the composition.

[0044] The following examples are presented for illustrative purposes only, and are not intended to be limiting.

EXAMPLES

[0045] Testing Methods

[0046] The experiments were conducted in a laboratory scale Denver flotation cell (Metso Minerals, Danville, PA) under semi-batch conditions (batch water, continuous air). In a typical experiment, 300 g of oil sand ore was added to 1.5 1 pre-heated water at 50°C at the impeller speed of 1000 rpm in a 2 1 rectangular cell. The flotation cell was kept at 50°C by using a hot water circulating bath. The pH of water/slurry was adjusted to 8.5 or by addition of sodium hydroxide or cement prior to addition of ore and the pH was monitored during the flotation process. The slurry was conditioned for 5 min. The slurry was then subjected to air bubble flotation using an airflow rate of 200 ml/min Froths were collected at time intervals of 2, 5, 10, 20 and 60 after flotation while agitation was paused for 30 sec. Bitumen recovery rates, solid and water contents were determined from solvent extraction on standard Soxhlet extractor units using toluene solvent. The experiments were run in triplicate experiments, with recovery rates being reproducible within ±5%.

[0047] Compositions of Oil Sands Samples

[0048] Samples of low and high grade Athabasca oil sands were obtained from Alberta Innovates Technology Futures, oil sands sample bank (Edmonton, Canada). The general composition of oil sands ores used in the examples is shown in Table 1.

[0049] Table 1

[0050] Compositions of Cements

[0051] API cements class A and G were obtained from Lehigh Cement Company (Edmonton, Canada). ReezCEM 800™ is a microfine blend of Class A cement and pozzolanic materials with particle size less than 15 μιη available from Pontis Energy Inc (Calgary, Canada). Bulk chemical composition by XRF analysis of cement samples used in the examples are given in Table 2.

[0052] Table 2

[0053] Example 1. Comparison of Bitumen Recovery from High Grade Oil

Sands [0054] In this example, bitumen was recovered from high grade oil sand ores using sodium hydroxide and API class A cement process aids. In these experiments, the pH of water was adjusted to 8.5 using NaOH or cement before the flotation process. As shown in Table 3, bitumen recovery in the presence of Portland cement resulted in higher bitumen recoveries than bitumen recovery in the presence of NaOH. Furthermore, the conditions for these improved recovery rates did not change the water chemistry with respect to the concentration of mono- and divalent cations.

[0055] Table 3

Cem A = API class A cement

[0056] Example 2. Comparison of Bitumen Recovery from Low Grade Oil

Sands

[0057] In this example, bitumen was recovered from low grade oil sand ores, using sodium hydroxide and API class A cement process aids. In these experiments, the pH of water was adjusted to 8.5 using NaOH or cement before the flotation process. As shown in Table 4, bitumen recovery in the presence of Portland cement resulted in higher bitumen recoveries than bitumen recovery in the presence of NaOH. Furthermore, the conditions for these improved recovery rates did not change the water chemistry with respect to the concentration of mono- and divalent cations.

[0058] Table 4

Cem A = API Class A cement

[0059] Figure 1 shows the bitumen recovery data as a function of time for low grade ore sample LG2 treated by NaOH and API Class A cement (Cem A). As shown in Figure 1, the use of Portland cement improves the liberation of bitumen from sand. For this LG2 sample, more than 70% of bitumen is liberated within 20 min of flotation compared to only 50% when NaOH was used.

[0060] Example 3. Effect of Dosage of Portland Cement on Bitumen Recovery

Rate

[0061] In this example, the effect of dosage of Portland cement on bitumen recovery rate was examined in an experiment using 100 - 1600 g/t of API Class A Portland cement on low grade oil sand sample LG3. Data are summarized in Table 5 and graphically represented in Figure 2. The results show that Portland cement can be used as an effective process aid at a wide range of dosages, and that the dosage of 750 g/t gave the maximum recovery rate of 90%.

[0062] Table 5

[0063] Example 4. Effect of pH on Bitumen Recovery Rates

[0064] In this example, the effect of dosage on bitumen recovery rate was examined in an experiment wherein the pH of water/slurry was adjusted to 8.5 or 10 by addition of sodium hydroxide or Portland cement prior to addition of ore and monitored during the flotation process. As shown in Table 6, Portland cement at both pH 8.5 and 10 results in higher recovery rate when compared to pH adjustments using sodium hydroxide. It was also noted that Portland cement increased bitumen recovery from pH 8.5 to 10, while under the same conditions bitumen recovery was reduced when sodium hydroxide was used. This is graphically represented in Figure 3. [0065] Table 6

[0066] Example 5. Effect of the Type of Portland Cement on Bitumen Recovery

[0067] In this example, the effect of the type of Portland cement on bitumen recovery from oil sand ores was assessed. Class A and G cements as well as a microfine cement, ReezCEM™, were utilized on a low grade oil sand sample of LG3. Data are summarized in Table 7. It was found that all types of Portland cement could be used as a process aid in bitumen recovery from oil sand ores.

[0068] Table 7

[0069] Example 6. Effect of Using Recycled Water From A Portland Cement Process

[0070] In this example, the use of recycled water from process comprising Portland cement was also examined. In this study, the process water was used after filtration for bitumen recovery using flotation. The pH of water was initially adjusted to 8.5 using Portland cement and a low grade ore sand sample from LG3 was used. As shown in Table 8, bitumen recoveries did not change within 5 cycles of water reuse, and no significant change in water chemistry was observed.

[0071] Table 8