SODIUM TRIPHOSPHATE AND CAUSTIC AS PROCESS AIDS FOR THE EXTRACTION OF BITUMEN FROM MINED OIL SANDS

A process of extracting bitumen from oil sand ores having a fines content up to about 60% and a bitumen content higher than about 6% is provided, comprising: determining a dosage (wt %) of caustic necessary to yield a desired primary bitumen recovery; determining an amount of caustic (wt %) and an amount of sodium triphosphate (wt %) which yields substantially the same desired primary bitumen recovery or greater as the dosage of caustic (wt %) alone; mixing the oil sand ore with heated water to produce an oil sand slurry; and adding the amounts of caustic (wt %) and sodium triphosphate (wt %) before, during or after mixing the oil sand ore with heated water to condition the oil sand slurry and to improve bitumen recovery from the oil sand ore; whereby the sum of the amounts of caustic (wt %) and sodium triphosphate (wt %) is substantially equal to the dosage of caustic (wt %) alone.

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Description
FIELD OF THE INVENTION

The present invention relates to a process of extracting bitumen from oil sand ores by adding a combination of sodium triphosphate and caustic (sodium hydroxide) to condition the oil sand slurry.

BACKGROUND OF THE INVENTION

Oil sand generally comprises water-wet sand grains held together by a matrix of viscous heavy oil or bitumen. Bitumen is a complex and viscous mixture of large or heavy hydrocarbon molecules. The Athabasca oil sand deposits may be efficiently extracted by surface mining which involves shovel-and-truck operations. The mined oil sand is trucked to crushing stations for size reduction, and fed into slurry preparation units where hot water and caustic (sodium hydroxide) are added to form an oil sand slurry. The oil sand slurry may be further conditioned by transporting it using a hydrotransport pipeline to a primary separation vessel (PSV) where the conditioned slurry is allowed to separate under quiescent conditions for a prescribed retention period into a top layer of bitumen froth, a middle layer of middlings (i.e., warm water, fines, residual bitumen), and a bottom layer of coarse tailings (i.e., warm water, coarse solids, residual bitumen). The bitumen froth, middlings and tailings are separately withdrawn. The bitumen froth is de-aerated, heated, and treated to produce diluted bitumen which is further processed to produce synthetic crude oil and other valuable commodities.

“Fines” are particles such as fine quartz and other heavy minerals, colloidal clay or silt generally having any dimension less than about 44 μm. “Coarse solids” are solids generally having any dimension greater than about 44 μm. Oil sand extraction typically involves processing ores which are relatively high in bitumen content and low in fines content. However, there exists an abundance of “poor ores” which alone yield poor bitumen recovery and consequently cannot be processed unless a high proportion of high-grade, good ores are blended into these dry ore feeds. “Poor ores” are oil sand ores generally having low bitumen content (about 6 to about 10%) and/or high fines content (greater than about 30%). In comparison, “good ores” are oil sand ores generally having high bitumen content (about 10 to about 12% or higher) and/or low fines content (less than about 20%).

Caustic is used in bitumen extraction to improve bitumen recovery and froth quality. Caustic promotes the release of natural surfactants from bitumen to the aqueous phase, precipitates divalent cations such as calcium and magnesium, modifies the electrical surface potential of bitumen and solids, adjusts the pH, and makes solids more hydrophilic, leading to better bitumen-solids separation. For an oil sand ore, there is normally an optimal caustic dosage at which the highest bitumen recovery can be obtained and the optimal dosage appears to be determined by both the fines content (Sanford, E., 1983, Can. J. Chem. Eng. 61:554-567) and the ore grade.

However, the use of caustic may create undesired consequences. Caustic is toxic and corrosive, impacting health and the environment and causing scaling on equipment. Compared to the caustic dosage for good ores, a higher caustic dosage is required for poor ores, but does not necessarily improve bitumen recovery and froth quality. Caustic disperses fines, hindering fines settling and tailings treatment. Higher caustic dosages induce bitumen emulsification which impairs froth treatment.

Accordingly, there is a need for a method of minimizing the amount of caustic used in bitumen extraction.

SUMMARY OF THE INVENTION

The current application is directed to a process of extracting bitumen from mined oil sand ores by adding a combination of sodium triphosphate and caustic to condition the oil sand slurry. It was surprisingly discovered that by conducting the process of the present invention, one or more of the following benefits may be realized:

(1) The combined use of sodium triphosphate and caustic has a synergistic effect, improving bitumen recovery and froth quality in poor (low-grade high-fines) and good ores.

(2) For good ores, the combined use of sodium triphosphate and caustic does not have any negative impact on processability.

(3) The combined use of sodium triphosphate and caustic requires a lower amount of total chemical addition than the use of caustic alone, and is more effective at much lower dosages than caustic alone.

(4) The combined use of sodium triphosphate and caustic minimizes the amount of caustic, negating problems normally encountered by use of high caustic dosages. Sodium triphosphate is non-toxic to humans, animals, and the environment; a scaling and corrosion inhibitor; reduces the chances of bitumen emulsification; and hydrolyzes such that divalent cations captured in chelating form may be released for fine solids coagulation in tailings treatment; and the hydrolyzed species (e.g., ATP which is nutritious and essential to life) may positively impact the environment and land reclamation.

Thus, use of the present invention conserves the amounts of process aids in bitumen extraction, and improves bitumen recovery and froth quality.

In one aspect, a process of extracting bitumen from oil sand ores having a fines content up to about 60% and a bitumen content higher than about 6% is provided, comprising:

    • determining a dosage (wt %) of caustic necessary to yield a desired primary bitumen recovery;
    • determining an amount of caustic (wt %) and an amount of sodium triphosphate (wt %) which yields substantially the same desired primary bitumen recovery or greater as the dosage of caustic (wt %) alone;
    • mixing the oil sand ore with heated water to produce an oil sand slurry; and
    • adding the amounts of caustic (wt %) and sodium triphosphate (wt %) before, during or after mixing the oil sand ore with heated water to condition the oil sand slurry and to improve bitumen recovery from the oil sand ore;
    • whereby the sum of the amounts of caustic (wt %) and sodium triphosphate (wt %) is substantially equal to the dosage of caustic (wt %).

In one embodiment, the amount of caustic ranges from about 0 wt % to about 0.05 wt % of poor oil sand ore. In one embodiment, the sufficient amount of sodium triphosphate ranges from about 0.005 wt % to about 0.05 wt % of poor oil sand ore.

In one embodiment, the amount of caustic ranges from about 0 wt % to about 0.05 wt % of good oil sand ore. In one embodiment, the amount of sodium triphosphate ranges from about 0.003 wt % to about 0.009 wt % of good oil sand ore.

In one embodiment, the caustic is sodium hydroxide.

BRIEF DESCRIPTION OF THE DRAWINGS

Referring to the drawings wherein like reference numerals indicate similar parts throughout the several views, several aspects of the present invention are illustrated by way of example, and not by way of limitation, in detail in the figures, wherein:

FIG. 1 is a schematic showing, in general, the extraction process for extracting bitumen from mined oil sand ore.

FIG. 2 is a graph showing primary bitumen recovery (%) as a function of dosages (wt %) of caustic or sodium triphosphate alone, or in combination, for poor oil sand AR.

FIG. 3 is a graph showing primary froth bitumen content (%) as a function of dosages (wt %) of caustic or sodium triphosphate alone, or in combination, for poor oil sand AR.

FIG. 4 is a graph showing primary froth solids content (%) as a function of dosages (wt %) of caustic or sodium triphosphate alone, or in combination, for poor oil sand AR.

FIG. 5 is a graph showing combined bitumen recovery (%) as a function of dosages (wt %) of caustic or sodium triphosphate alone, or in combination, for poor oil sand AR.

FIG. 6 is a graph showing primary bitumen recovery (%) as a function of dosages (wt %) of caustic or sodium triphosphate alone, or in combination, for poor oil sand AD.

FIG. 7 is a graph showing primary froth bitumen content (%) as a function of dosages (wt %) of caustic or sodium triphosphate alone, or in combination, for poor oil sand AD.

FIG. 8 is a graph showing primary froth solids content (%) as a function of dosages (wt %) of caustic or sodium triphosphate alone, or in combination, for poor oil sand AD.

FIG. 9 is a graph showing combined bitumen recovery (%) as a function of dosages (wt %) of caustic or sodium triphosphate alone, or in combination, for poor oil sand AD.

FIG. 10 is a graph showing combined froth bitumen content (%) as a function of dosages (wt %) of caustic or sodium triphosphate alone, or in combination, for poor oil sand AD.

FIG. 11 is a graph showing primary bitumen recovery (%) as a function of dosages (wt %) of caustic or sodium triphosphate alone, or in combination, for poor oil sand AAX.

FIG. 12 is a graph showing primary froth bitumen content (%) as a function of dosages (wt %) of caustic or sodium triphosphate alone, or in combination, for poor oil sand AAX.

FIG. 13 is a graph showing primary froth solids content (%) as a function of dosages (wt %) of caustic or sodium triphosphate alone, or in combination, for poor oil sand AAX.

FIG. 14 is a graph showing combined bitumen recovery (%) as a function of dosages (wt %) of caustic or sodium triphosphate alone, or in combination, for poor oil sand AAX.

FIG. 15 is a graph showing primary bitumen recovery (%) as a function of dosages (wt %) of caustic or sodium triphosphate alone, or in combination, for good ore AR12.

FIG. 16 is a graph showing primary froth bitumen content (%) as a function of dosages (wt %) of caustic or sodium triphosphate alone, or in combination, for good ore AR12.

FIG. 17 is a graph showing primary froth solids content (%) as a function of dosages (wt %) of caustic or sodium triphosphate alone, or in combination, for good ore AR12.

FIG. 18 is a graph showing combined bitumen recovery (%) as a function of dosages (wt %) of caustic or sodium triphosphate alone, or in combination, for good ore AR12.

FIG. 19 is a graph showing combined froth bitumen content (%) as a function of dosages (wt %) of caustic or sodium triphosphate alone, or in combination, for good ore AR12.

 DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The detailed description set forth below in connection with the appended drawings is intended as a description of various embodiments of the present invention and is not intended to represent the only embodiments contemplated by the inventor. The detailed description includes specific details for the purpose of providing a comprehensive understanding of the present invention. However, it will be apparent to those skilled in the art that the present invention may be practiced without these specific details.

The present invention relates generally to a process of extracting bitumen from mined oil sand ores by adding a combination of sodium triphosphate and caustic to condition the oil sand slurry.

In one embodiment of the process of the present invention useful in extracting bitumen from oil sand ores, oil sand is mined from an oil sand rich area such as the Athabasca Region of Alberta. The oil sand ore may comprise a fines content up to about 60% and a bitumen content greater than about 6%.

FIG. 1 is a general schematic of a bitumen extraction process from mined oil sand ore. The oil sand is mixed with heated water in a slurry preparation unit. The slurry preparation unit may comprise a tumbler, screening device and pump box; however, it is understood that any slurry preparation unit known in the art can be used.

In addition to the oil sand and water, sodium triphosphate and caustic are also added to the slurry preparation unit to aid in conditioning the oil sand slurry. As used herein, the term “sodium triphosphate” means the sodium salt of the polyphosphate penta-anion which is the conjugate base of triphosphoric acid. Synonyms, abbreviations, and other names for sodium triphosphate include STP, STPP, sodium tripolyphosphate, and TPP. Sodium triphosphate has the molecular formula Na5P3O10. Triphosphate is a chelating agent which binds strongly to metal cations such as, for example, calcium and magnesium. Since polyphosphates are hydrolyzed into simpler phosphates, polyphosphates are non-toxic to humans, animals, and the environment.

The amount of caustic is determined by initially testing varying caustic dosages to elucidate the optimal caustic dosage which yields a desired primary bitumen recovery. In one embodiment, the sufficient amount of caustic ranges from about 0.01 wt % to about 0.05 wt % of poor oil sand ore. In one embodiment, the sufficient amount of caustic ranges from about 0.01 wt % to about 0.05 wt % of good oil sand ore. In one embodiment, the caustic is sodium hydroxide.

The amount of sodium triphosphate is determined by the optimal caustic dosage and type of oil sand ore. In one embodiment, the dosage for each of caustic and sodium triphosphate does not exceed 0.05 wt % since higher dosages are impractical in industrial operations due to costs and efforts to conserve process aids. In one embodiment, the sufficient amount of sodium triphosphate ranges from about 0.005 wt % to about 0.05 wt % of poor oil sand ore. In one embodiment, the sufficient amount of sodium triphosphate ranges from about 0.003 wt % to about 0.009 wt % of good oil sand ore.

The sodium triphosphate and caustic may be added to the water prior to mixing with oil sand, directly into the slurry preparation unit during mixing, or to the oil sand slurry prepared prior to hydrotransport/slurry conditioning. Preferably, the sodium triphosphate and caustic are added to the heated water.

Following the addition of sodium triphosphate and caustic, the oil sand slurry may be screened through a screen portion, where additional water may be added to clean the rejects (e.g., oversized rocks) prior to delivering the rejects to a rejects pile. The screened oil sand slurry is collected in a vessel such as pump box where the oil sand slurry is then pumped through a hydrotransport pipeline (slurry conditioning), which pipeline is of a adequate length to ensure sufficient conditioning of the oil sand slurry, e.g., thorough digestion/ablation/dispersion of the larger oil sand lumps, coalescence of released bitumen flecks and aeration of the coalesced bitumen droplets.

The conditioned oil sand slurry is then fed to a bitumen separation vessel (also referred to as a primary separation vessel or PSV), which bitumen separation vessel operates under somewhat more quiescent conditions to allow the bitumen droplets to rise to the top of the vessel and form bitumen froth, which froth over flows to the launder and is collected for further froth treatment. Tailings are either discarded or further treated for additional bitumen recovery.

Exemplary embodiments of the present invention are described in the following Example, which is set forth to aid in the understanding of the invention, and should not be construed to limit in any way the scope of the invention as defined in the claims which follow thereafter.

Example 1

Samples of three poor ores and one good ore were tested (Table 1). The three poor ores had bitumen contents ranging from 8.7% to 9.6%, with fines contents from 26% up to 39%. The good ore had a bitumen content of 11.9% and a fines content of 16%.

TABLE 1 Classification of Ore Poor Ore Good Ore Designation AR AAX AD AR12 Bitumen, % 9.0 8.7 9.6 11.9 Solids < 44 μm, % 26 39 38 16 Solids d50, μm 213 92 80 130

Batch extraction unit testing was conducted, using blended process water, conducting conditioning at 50° C., and testing different dosages of caustic alone, sodium triphosphate alone, and a combination of caustic and sodium triphosphate to assess whether a combination of process aids might have a synergistic effect. The dosages were based upon the dry oil sand weight (500 g for each test). Initial tests involving addition of caustic alone were conducted to find an optimal caustic dosage for each ore, followed by subsequent tests involving addition of sodium triphosphate alone, and in combination with caustic. The dosages for caustic or sodium triphosphate did not exceed 0.05 wt % since higher dosages are impractical in plant operations due to costs and efforts to conserve process aids.

The data were reconciled for material balance using the Bilmat™ program, Version 9.2, 2006 (Algosys Inc., Quebec, CA). The extraction performance was indicated by the primary, secondary, and wall bitumen recoveries (Rp, Rs, Rw), which were calculated using equation (1):

R i = M if · X B , if M os · X B , os ( 1 )

where R denotes bitumen recovery; M is the mass; X is the mass fraction; the subscript i represents either primary (p), secondary (s), or wall (w); and the subscripts f, B, and os stand for froth, bitumen, and oil sand, respectively.

The combined recovery (Rc) which is the sum of the primary and secondary recoveries was calculated using equation (2):


Rc=Rp+Rs  (2)

The total recovery (Rt) which is the sum of the primary, secondary, and wall bitumen recoveries was calculated using equation (3):


Rt=Rp+Rs+Rw  (3)

Poor Ore AR

For poor ore AR, the primary bitumen recovery was 11.6% when no process aid was used (Table 2). The addition of caustic improved processability. As the primary bitumen recovery did not substantially change when the caustic dosage was increased from 0.03% to 0.04%, 0.03% was selected as the dosage for further testing with sodium triphosphate addition. When the caustic dosage was further increased to 0.05%, the primary bitumen recovery increased to 32.2%.

The primary bitumen recovery and primary froth bitumen content generally increased with increasing chemical dosage (FIGS. 2 and 3). The results for caustic alone and sodium triphosphate alone were almost identical for primary bitumen recovery (FIG. 2) and primary froth bitumen content (FIG. 3), indicating that sodium triphosphate was as effective as caustic. The combined use of caustic and sodium triphosphate is preferred due to having a synergistic effect. The best performance was achieved with the combination of reagents (caustic at 0.03 wt % and sodium triphosphate at 0.05 wt %) which yielded a primary bitumen recovery of 53.3% and a primary froth bitumen content of 44.6%.

TABLE 2 Chemical Bitumen Recovery, % Froth Quality Test Dosage, wt % Wall Bitumen Content, % Solids Content, % Series Caustic STP Primary Secondary Froth Combined Total Primary Secondary Combined Primary Secondary Combined 1 0 0 11.6 10.4 1.1 21.9 23.0 21.7 15.7 18.4 6.9 30.1 19.7 0.01 0 13.8 15.0 2.2 28.8 31.0 24.8 18.6 21.2 8.5 32.6 23.0 0.02 0 15.5 14.8 2.0 30.3 32.3 25.9 17.6 21.2 8.5 31.4 22.1 0.03 0 21.0 17.7 2.1 38.7 40.8 28.9 19.8 23.9 9.0 29.6 20.5 0.04 0 20.2 17.1 2.7 37.3 40.0 29.4 21.7 25.3 9.3 31.4 21.2 0.05 0 32.2 18.6 3.1 50.8 53.9 31.1 22.9 27.5 10.4 28.9 18.5 2 0 0.01 13.9 9.2 0.7 23.0 23.7 21.0 10.4 15.0 7.3 18.4 13.6 0 0.02 16.3 8.7 0.5 25.0 25.5 25.9 9.8 16.5 7.0 17.4 13.1 0 0.03 20.5 9.6 0.4 30.1 30.5 29.3 11.6 19.7 6.8 20.9 14.4 0 0.04 26.8 13.6 0.7 40.4 41.1 32.5 12.4 21.1 7.8 19.9 14.7 0 0.05 27.7 15.4 0.8 43.1 44.0 33.1 18.0 25.5 8.3 24.8 16.6 3 0.01 0.01 18.5 8.8 0.5 27.2 27.7 28.6 15.9 22.7 5.6 29.6 16.7 0.01 0.02 20.3 12.3 0.6 32.6 33.2 30.8 15.6 22.6 5.9 27.0 17.3 0.01 0.03 25.6 18.8 0.8 44.3 45.2 35.9 19.9 26.8 6.8 29.5 19.8 0.01 0.04 30.5 17.9 0.8 48.4 49.2 38.6 22.0 30.2 9.9 27.9 19.0 0.01 0.05 29.6 20.7 1.0 50.3 51.3 36.8 23.3 29.7 7.9 29.2 19.1 4 0.03 0.01 28.5 17.4 0.9 45.8 46.8 37.0 20.1 28.0 7.2 29.9 19.2 0.03 0.02 29.9 16.7 0.8 46.6 47.4 37.4 21.0 29.2 9.7 26.7 18.2 0.03 0.03 32.6 20.0 0.9 52.6 53.6 38.8 24.3 31.6 9.2 28.8 18.9 0.03 0.04 42.7 26.0 1.1 68.7 69.8 42.5 27.9 35.5 10.5 29.0 19.4 0.03 0.05 53.3 20.5 1.1 73.7 74.9 44.6 28.3 38.5 12.6 28.4 18.5

For the primary froth solids content, sodium triphosphate alone or in combination with caustic (0.01 wt %) resulted in lower froth solids contents than the use of caustic alone (FIG. 4). When caustic (0.03 wt %) was combined with different dosages of sodium triphosphate (0.01-0.05 wt %), the froth solids contents were similar to those obtained with the use of caustic alone.

For a fair comparison, the total chemical dosage (caustic and sodium triphosphate dosages) should be considered. When sodium triphosphate (0.01 wt %) and caustic (0.03 wt %) were combined, the total chemical dosage was 0.04 wt %. Compared to caustic alone (0.04 wt %), the primary recovery increased from 20.2% to 28.5% and primary froth bitumen content increased from 29.4% to 37% (Table 3). The results of primary bitumen recovery and primary froth bitumen content were grouped by the total chemical dosages for oil sand AR. For every group at the same total chemical dosage, the combined use of caustic and sodium triphosphate improved the primary froth quality. The primary bitumen recovery was also improved by the combined uses of caustic and sodium triphosphate, except for the case with a total chemical dosage of 0.03 wt %, at which the primary recoveries did not differ.

TABLE 3 Chemical Dosage, wt % Primary Froth Bitumen Group Total Caustic STP Recovery, % Content, % 1 0.02 0.02 0 15.5 25.9 0.02 0 0.02 16.3 25.9 0.02 0.01 0.01 18.5 28.6 2 0.03 0.03 0 21.0 28.9 0.03 0 0.03 20.5 29.3 0.03 0.01 0.02 20.3 30.8 3 0.04 0.04 0 20.2 29.4 0.04 0 0.04 26.8 32.5 0.04 0.01 0.03 25.6 35.9 0.04 0.03 0.01 28.5 37.0 4 0.05 0.05 0 32.2 31.1 0.05 0 0.05 27.7 33.1 0.05 0.01 0.04 30.5 38.6 0.05 0.03 0.02 29.9 37.4

Similar to the primary bitumen recovery (FIG. 2), the combined bitumen recovery (sum of the primary plus secondary recoveries; FIG. 5) was also improved by the combination of caustic (0.03 wt %) and sodium triphosphate at various dosages.

Poor Ore AD

Poor ore AD processed reasonably well with a primary recovery of 70.2% and a total recovery of 87.7% when no process aid was used (Table 4). The caustic dosage of 0.02 wt % was selected based on the raw primary froth amounts obtained from test series #1. Based upon the total bitumen recoveries, it appears that 0.01 wt % should be the optimal caustic dosage; thus, the caustic dosage of 0.02 wt % used in test series #3 was higher than the optimal dosage.

Sodium triphosphate performed much better than caustic in regards to primary bitumen recovery (FIG. 6) and primary froth quality (FIG. 7). The lowest primary bitumen recovery was 82.9% (sodium triphosphate, 0.005 wt %) which was still higher than the highest primary bitumen recovery of 78.9% obtained with caustic (0.04 wt %). For caustic, the primary froth bitumen content was about 50% and did not generally change with increasing caustic dosage. In contrast, the primary froth bitumen content was higher than 60% with sodium triphosphate. The highest primary froth bitumen content was 68.2% with sodium triphosphate at 0.02 wt %. Sodium triphosphate also reduced the primary froth solids content when compared to caustic (FIG. 8). Sodium triphosphate performed significantly better than caustic, significantly increasing the primary bitumen recovery and the froth bitumen content, and reducing the froth solids content. The overall performance using sodium triphosphate at 0.005 wt % was superior than using caustic at 0.05 wt %.

For the combination of caustic and sodium triphosphate, the performance was generally better than caustic. Significant increases were observed for the primary bitumen recovery (FIG. 6) and the primary froth bitumen content (FIG. 7). For the primary froth solids content, the results of the combination of caustic and sodium triphosphate were similar to those of caustic (FIG. 8).

TABLE 4 Chemical Bitumen Recovery, % Froth Quality Test Dosage, wt % Wall Bitumen Content, % Solids Content, % Series Caustic STP Primary Secondary Froth Combined Total Primary Secondary Combined Primary Secondary Combined 1 0 0 70.2 15.9 1.6 86.1 87.7 50.3 11.6 42.1 8.2 24.4 19.2 0.01 0 73.6 17.9 1.6 91.5 93.2 50.0 13.6 40.2 9.2 22.3 21.5 0.02 0 70.1 18.2 1.9 88.3 90.3 48.6 11.9 41.7 9.2 26.8 17.7 0.03 0 72.6 16.7 2.1 89.3 91.4 48.1 12.3 41.9 9.8 27.0 18.4 0.04 0 78.9 11.9 1.8 90.8 92.7 48.7 12.2 44.0 10.6 26.7 18.0 0.05 0 78.6 12.1 2.2 90.7 92.9 48.6 11.4 46.0 9.7 34.1 18.9 2 0 0.005 82.9 6.8 2.0 89.7 91.8 62.3 12.2 54.9 8.3 22.6 29.2 0 0.01 86.1 6.3 1.8 92.4 94.2 60.1 10.9 54.1 8.1 22.9 25.5 0 0.02 84.5 6.4 1.1 90.9 92.1 68.2 10.9 58.7 8.2 20.7 21.4 0 0.03 85.5 5.6 1.2 91.1 92.3 62.7 12.4 57.3 10.5 24.8 24.0 0 0.05 83.9 6.9 1.1 90.8 91.9 63.5 10.9 57.7 8.7 27.2 22.3 3 0.02 0.005 80.8 9.5 1.7 90.2 91.9 50.6 10.6 46.4 8.5 27.3 20.2 0.02 0.01 77.9 5.7 1.2 83.6 84.8 53.0 10.6 49.0 8.8 24.0 21.3 0.02 0.02 87.1 4.5 1.0 91.6 92.6 68.5 11.7 61.1 9.7 19.9 23.0 0.02 0.03 85.9 6.1 1.2 91.9 93.2 58.6 12.3 52.1 10.0 20.3 23.6 0.02 0.05 88.9 2.7 1.0 91.6 92.6 68.8 10.9 64.9 10.1 22.6 19.4

FIG. 9 shows the results of the combined bitumen recovery. The results of all three test series were similar (about 90%) and did not appear to change with the chemical dosages. However, sodium triphosphate alone and in combination with caustic significantly improved the combined froth quality by increasing the combined froth bitumen content compared to caustic alone (FIG. 10).

The results of primary bitumen recovery and froth bitumen content for poor ore AD were grouped by the total chemical dosage (Table 5). For every group at the same total chemical dosage, sodium triphosphate alone or in combination with caustic outperformed caustic alone.

TABLE 5 Chemical Dosage, wt % Primary Froth Bitumen Group Total Caustic STP Recovery, % Content, % 1 0.01 0.01 0 73.6 40.2 0.005 0 0.005 82.9 54.9 0.01 0 0.01 86.1 54.1 2 0.02 0.02 0 70.1 41.7 0.02 0 0.02 84.5 58.7 3 0.03 0.03 0 72.6 41.9 0.03 0 0.03 85.5 57.3 0.025 0.02 0.005 80.8 46.4 0.03 0.02 0.01 77.9 49.0 4 0.04 0.04 0 78.9 44.0 0.04 0.02 0.02 87.1 61.1 5 0.05 0.05 0 78.6 46.0 0.05 0 0.05 83.9 57.7 0.05 0.02 0.03 85.9 52.1

Poor Ore AAX

Ore AAX was a very poor processing ore. The primary bitumen recovery was low at 13.0% coupled with a low primary froth bitumen content at 19.7% when no process aid was used (Table 6). Even at the highest caustic dosage (0.05 wt %), the primary recovery remained low at 26.7%, and did not appear to change with the increased caustic dosage from 0.02 wt % to 0.04 wt %. The dosage of 0.03 wt % was thus not necessarily the optimal dosage.

TABLE 6 Chemical Bitumen Recovery, % Froth Quality Test Dosage, wt % Wall Bitumen Content, % Solids Content, % Series Caustic STP Primary Secondary Froth Combined Total Primary Secondary Combined Primary Secondary Combined 1 0 0 13.0 8.6 0.6 21.6 22.2 19.7 11.6 15.5 7.8 16.2 12.2 0.01 0 16.9 11.0 0.7 27.9 28.6 26.0 11.1 17.0 8.6 15.2 12.6 0.02 0 21.6 11.2 0.7 32.8 33.5 32.1 13.3 21.7 8.1 15.3 12.1 0.03 0 23.0 12.9 0.8 35.9 36.7 28.4 12.4 19.3 7.5 13.5 10.8 0.04 0 22.9 15.4 1.0 38.3 39.3 29.4 13.9 20.3 7.8 14.9 12.0 0.05 0 26.7 16.2 1.1 42.9 44.0 34.8 15.7 23.8 7.0 14.8 11.5 2 0 0.005 20.7 10.4 0.4 31.1 31.5 29.2 13.3 20.9 6.9 17.7 12.6 0 0.01 26.4 10.7 0.6 37.1 37.7 32.9 11.2 21.1 7.0 16.6 12.2 0 0.02 36.7 13.4 0.6 50.1 50.7 41.0 13.3 26.4 6.5 18.4 12.8 0 0.03 37.8 14.9 0.6 52.6 53.3 41.7 13.8 26.5 6.3 13.9 10.4 0 0.05 41.6 14.9 0.9 56.5 57.3 42.0 17.3 30.5 8.4 14.6 11.2 3 0.03 0.005 57.7 16.1 3.1 73.8 76.9 51.9 20.1 38.6 7.9 15.6 11.1 0.03 0.01 46.5 17.9 1.0 64.4 65.4 39.0 15.7 27.6 8.2 16.0 12.0 0.03 0.02 50.6 17.7 1.2 68.3 69.4 41.0 18.9 31.5 7.1 14.0 10.1 0.03 0.03 54.2 15.7 2.5 69.9 72.4 47.0 20.0 36.1 8.1 16.0 11.3 0.03 0.05 59.5 16.1 1.4 75.6 77.0 49.6 20.7 38.3 9.4 18.8 13.1

Sodium triphosphate outperformed caustic, increasing the primary bitumen recovery (FIG. 11) and froth bitumen content (FIG. 12), and decreasing the froth solids content (FIG. 13). The best performance for caustic was obtained at the highest dosage of 0.05 wt %. A similar performance was achieved at a sodium triphosphate dosage as low as 0.01 wt %. The combined use of caustic and sodium triphosphate had a synergistic effect, yielding greater increases in the primary bitumen recovery (FIG. 11) and the primary froth bitumen content (FIG. 12) compared to either caustic or sodium triphosphate. The best performance was achieved with the combination of reagents (the lowest sodium triphosphate dosage at 0.005 wt % and caustic at 0.03 wt %) which yielded a primary bitumen recovery of 57.7% and a primary froth bitumen content of 51.9%. For the primary froth solids content, the results of the combination of caustic and sodium triphosphate were similar to those of caustic (FIG. 13). Sodium triphosphate alone or in combination with caustic improved the combined bitumen recovery when compared to caustic (FIG. 14). The trends for the combined bitumen recovery are similar to those for the primary bitumen recovery (FIG. 11).

The results of the primary bitumen recovery and the primary froth bitumen content for poor ore AAX were grouped by the total chemical dosage (Table 7). For every group at the same total chemical dosage, sodium triphosphate alone or in combination with caustic (0.03 wt %) performed significantly better than caustic.

TABLE 7 Chemical Dosage, wt % Primary Froth Bitumen Group Total Caustic STP Recovery, % Content, % 1 0.01 0.01 0 16.9 26.0 0.005 0 0.005 20.7 29.2 0.01 0 0.01 26.4 32.9 2 0.02 0.02 0 21.6 32.1 0.02 0 0.02 36.7 41.0 3 0.03 0.03 0 23.0 28.4 0.03 0 0.03 37.8 41.7 4 0.04 0.04 0 22.9 29.4 0.04 0.03 0.01 46.5 39.0 0.035 0.03 0.005 57.7 51.9 5 0.04 0.04 0 22.9 29.4 0.04 0.03 0.01 46.5 39.0 0.035 0.03 0.005 57.7 51.9

Good Ore AR12

Testing of a good ore was conducted to confirm whether any of the process aids might have negative effects on the processability. Ore AR12 was a good processing ore, yielding a total recovery of 97.5% when no process aid was used (Table 8). Caustic and sodium triphosphate, alone or in combination, had little effect on the total bitumen recovery, but improved the primary bitumen recovery and froth quality.

The primary bitumen recovery was about 88% when no process aid was used (FIG. 15). When caustic (0.01 wt %) was used, the primary bitumen recovery increased to 92.5% and did not appear to change as the dosage increased. With sodium triphosphate (0.006 wt %), the primary bitumen recovery reached 92.8%. The combination of caustic (0.01 wt %) and sodium triphosphate (0.003 wt %) yielded a primary bitumen recovery of 94.0%.

Without any process aid, the primary froth bitumen content was 52.9% (FIG. 16). The primary froth bitumen content increased with increasing caustic dosage, reaching 61.7% at the highest caustic dosage (0.03 wt %). With sodium triphosphate (0.006 wt %), the bitumen content was 57.9%. The combined use of caustic and sodium triphosphate had a synergistic effect, with the primary froth bitumen content sharply increasing as the sodium triphosphate dosage increased. With sodium triphosphate (0.009 wt %) and caustic (0.01 wt %), the primary froth bitumen content reached 64.6%. For the primary froth solids content (FIG. 17), there were no noticeable differences among the various process aids.

The effects of sodium triphosphate alone and in combination with caustic on combined bitumen recovery are shown in FIG. 18. The results did not appear to change with increased dosage and were within the experimental error range. However, the combined froth bitumen quality was significantly improved by the combined use of caustic and sodium triphosphate (FIG. 19) as was the case for the primary froth bitumen content (FIG. 16). Overall, the results indicate that use of sodium triphosphate alone and in combination with caustic did not have any negative impacts on the processability of the good ore.

TABLE 8 Chemical Bitumen Recovery, % Froth Quality Test Dosage, wt % Wall Bitumen Content, % Solids Content, % Series Caustic STP Primary Secondary Froth Combined Total Primary Secondary Combined Primary Secondary Combined 1 0 0 88.0 7.7 1.7 95.8 97.5 52.9 29.6 49.8 12.3 22.2 13.6 0.01 0 92.5 3.4 2.1 95.9 98.0 55.7 28.3 53.9 12.8 24.7 13.6 0.02 0 91.9 3.2 2.4 95.1 97.5 59.3 34.1 57.9 12.8 23.1 13.4 0.03 0 92.2 3.3 2.2 95.5 97.8 61.7 31.5 59.7 13.1 18.8 13.4 2 0 0.003 91.1 4.7 2.1 95.7 97.8 53.9 28.9 51.8 13.1 23.5 14.0 0 0.006 92.8 3.1 2.0 95.9 97.9 57.9 27.2 55.8 13.9 28.3 14.9 0 0.009 93.1 2.7 1.9 95.9 97.7 57.5 25.4 55.5 14.1 29.1 15.1 3 0.01 0.003 94.0 1.8 1.9 95.8 97.7 58.1 28.9 57.1 13.6 27.4 14.1 0.01 0.006 94.4 2.0 1.4 96.5 97.9 61.8 25.5 60.0 13.7 25.1 14.2 0.01 0.009 93.6 1.8 1.4 95.4 96.8 64.6 30.1 63.2 13.1 22.0 13.4

From the foregoing description, one skilled in the art can easily ascertain the essential characteristics of this invention, and without departing from the spirit and scope thereof, can make various changes and modifications of the invention to adapt it to various usages and conditions. Thus, the present invention is not intended to be limited to the embodiments shown herein, but is to be accorded the full scope consistent with the claims, wherein reference to an element in the singular, such as by use of the article “a” or “an” is not intended to mean “one and only one” unless specifically so stated, but rather “one or more”. All structural and functional equivalents to the elements of the various embodiments described throughout the disclosure that are known or later come to be known to those of ordinary skill in the art are intended to be encompassed by the elements of the claims. Moreover, nothing disclosed herein is intended to be dedicated to the public regardless of whether such disclosure is explicitly recited in the claims.

Claims

1. A process of extracting bitumen from an oil sand ore having a fines content up to about 60% and a bitumen content higher than about 6%, comprising: whereby the sum of the amounts of caustic (wt %) and sodium triphosphate (wt %) is substantially equal to the dosage of caustic (wt %) alone.

determining a dosage (wt %) of caustic necessary to yield a desired primary bitumen recovery;
determining an amount of caustic (wt %) and an amount of sodium triphosphate (wt %) which yields substantially the same desired primary bitumen recovery or greater as the dosage of caustic (wt %) alone;
mixing the oil sand ore with heated water to produce an oil sand slurry; and
adding the amounts of caustic (wt %) and sodium triphosphate (wt %) before, during or after mixing the oil sand ore with heated water to condition the oil sand slurry and to improve bitumen recovery from the oil sand ore;

2. The process of claim 1, wherein the bitumen content ranges from about 6% to about 10%, the fines content is greater than about 25%, the caustic amount ranges from about 0 wt % to about 0.05 wt %, and the sodium triphosphate amount ranges from about 0.005 wt % to about 0.05 wt %.

3. The process of claim 2, wherein the bitumen content is about 8%, the fines content is about 40%, the caustic amount is about 0.03 wt %, and the sodium triphosphate amount is about 0.005 wt %.

4. The process of claim 2, wherein the bitumen content is about 9%, the fines content is about 26%, the caustic amount is about 0.03 wt %, and the sodium triphosphate amount is about 0.05 wt %.

5. The process of claim 2, wherein the bitumen content is about 9.5%, the fines content is about 35%, the caustic amount ranges from about 0.01 wt % to about 0.02 wt %, and the sodium triphosphate amount ranges from about 0.005 wt % to about 0.05 wt %.

6. The process of claim 1, wherein the bitumen content is greater than about 10%, the fines content is less than about 20%, the caustic amount ranges from about 0.01 wt % to about 0.05 wt %, and the sodium triphosphate amount ranges from about 0.003 wt % to about 0.009 wt %.

7. The process of claim 6, wherein the bitumen content is about 12%, the fines content is about 16%, the caustic amount is about 0.01 wt %, and the sodium triphosphate amount is about 0.003 wt %.

8. The process of claim 1, wherein a total dosage of caustic and sodium triphosphate is about 0.04 wt %, wherein the caustic amount ranges from about 0.01 wt % to about 0.03 wt %, and the sodium triphosphate amount ranges from about 0.01 wt % to about 0.03 wt %.

9. The process of claim 1, wherein the caustic comprises sodium hydroxide.

Patent History
Publication number: 20140151270
Type: Application
Filed: Dec 4, 2012
Publication Date: Jun 5, 2014
Applicant: Syncrude Canada Ltd. in trust for the owners of the Syncrude Project (Fort McMurray)
Inventors: JUN LONG (Edmonton), YONG GU (Edmonton)
Application Number: 13/705,015
Classifications
Current U.S. Class: Inorganic (only) Liquid (208/391)
International Classification: C10G 1/04 (20060101);