CA2581586A1 - Extraction of bitumen from oil sands using lime - Google Patents
Extraction of bitumen from oil sands using lime Download PDFInfo
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- CA2581586A1 CA2581586A1 CA 2581586 CA2581586A CA2581586A1 CA 2581586 A1 CA2581586 A1 CA 2581586A1 CA 2581586 CA2581586 CA 2581586 CA 2581586 A CA2581586 A CA 2581586A CA 2581586 A1 CA2581586 A1 CA 2581586A1
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- C—CHEMISTRY; METALLURGY
- C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
- C10G—CRACKING HYDROCARBON OILS; PRODUCTION OF LIQUID HYDROCARBON MIXTURES, e.g. BY DESTRUCTIVE HYDROGENATION, OLIGOMERISATION, POLYMERISATION; RECOVERY OF HYDROCARBON OILS FROM OIL-SHALE, OIL-SAND, OR GASES; REFINING MIXTURES MAINLY CONSISTING OF HYDROCARBONS; REFORMING OF NAPHTHA; MINERAL WAXES
- C10G1/00—Production of liquid hydrocarbon mixtures from oil-shale, oil-sand, or non-melting solid carbonaceous or similar materials, e.g. wood, coal
- C10G1/04—Production of liquid hydrocarbon mixtures from oil-shale, oil-sand, or non-melting solid carbonaceous or similar materials, e.g. wood, coal by extraction
- C10G1/047—Hot water or cold water extraction processes
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Abstract
In a method for enhancing the efficiency of bitumen recovery from oil sands ore, CaO lime (or Ca(OH)2) is mixed into an oil sands ore-water slurry prior to or during the operation of slurry-based bitumen extraction processes. The lime is introduced at dosages effective to reduce the electro-chemical attraction between clay particles and bitumen in the slurry, thereby promoting detachment of clay particles from bitumen droplets in the ore-wate r slurry. This occurs because water-soluble asphaltic acids formed at the bitumen-water interface act as surfactants and eliminate the activity of Ca2+ and Mg2+ ions binding the cla y particles and bitumen together. The detachment of clay particles promotes the attachment o f air bubbles to the bitumen droplets, thereby forming a bitumen-rich froth which will float to t he surface of the ore--water slurry, thus facilitating bitumen recovery.
Description
EXTRACTION OF BITUMEN FROM OIL SANDS USING LIME
FIELD OF THE INVENTION
The present invention relates to processes for extracting bitumen from oil sands.
BACKGROUND OF THE INVENTION
The oil sands deposits of northern Alberta in Canada contain about 142 billion cubic meters (or 890 billion barrels) of bitumen, thus constituting the largest oil sands deposit in the world. In the Athabasca of Alberta, the oil sands deposits are typically composed of (by weight) io about 12% bitumen, 82% to 85% mineral matter (solids) and 3% to 6% water.
Of the solids fraction, the solids smaller than 45 microns in size (i.e., silt and clay) are referred to as fines.
The clay fraction of the fines can be a significant factor in processes for both extraction of bitumen and disposal of oil sands tailings (i.e., residue from primary oil sands processing).
The bitumen content of the Athabasca deposits has been commercially utilized by oil sands ore-water slurry-based extraction processes and thermal in-situ processes and upgraded to synthetic crude oil at a production capacity of over one million barrels per day. In the major bitumen recovery operations in the Athabasca region, bitumen is produced from the surface-mineable oil sands using water-slurry-based extraction processes, in which the oil sands "ore"
(i.e., the raw oil sands material, as excavated from the oil sands deposits) is mixed with hot water to form an ore-water slurry. Asphaltic acids present in bitumen, which contain partly aromatic, oxygen functional groups such as phenolic, carboxylic and sulphonic types, become water-soluble, especially when the ore-water slurry's pH (i.e., a measure of acidity expressed as the minus logarithm of the hydrogen ions concentration: pH = -log [H+]) is slightly over 7, and act as surfactants reducing the surface and interfacial tensions. Reduction of the surface and interfacial tensions of the ore-water slurry system results in the disintegration of the ore structure and liberation of bitumen from the ore. Accordingly, the water-soluble fraction of bitumen asphaltenes plays an important role in the recovery of bitumen from the surface-mineable oil sands ore.
It is know to increased the water-soluble fraction of bitumen by increasing the pH of the oil sands ore-water slurry by the addition of caustic soda (NaOH), soda ash (NaZCO3), or any salt of weak acid and strong base (hydrolysis of which would be basic).
Alternatively, this desirable result can be achieved by modifying the asphaltene molecules contained in bitumen by oxidation, sulfonation and/or sulfoxidation reactions to water soluble surfactants, which reduce the surface and interfacial tensions: see International Application No. PCT/CA2005/001875 (WIPO Pub.
No. WO 2006/060917).
Liberated bitumen has to be recovered from the ore-water slurry by separation methods based on density differences. Bitumen density is very close to the density of water;
consequently, bitumen needs to become effectively "attached" to air bubbles in order for it to be recovered from the ore-water slurry system by means of flotation. However, clay particles present in the ore can become attached to bitumen droplets, thus preventing the desired interaction between bitumen and air bubbles. This undesirable attachment of clay particles to bitumen is promoted by calcium (Ca 2) and magnesium (Mg2+) ions present in the process water.
Another significant factor with respect to bitumen recovery is that the temperature of the ore-water slurry has to be above a critical temperature, above which bitumen becomes mobile enough (i.e., having sufficiently low viscosity) to enfold the air bubble (and thus facilitate flotation). This critical temperature for the Athabasca bitumen is reported by several researchers to be around 32 C.
In summary, liberation of bitumen from oil sands matrix and attachment of air bubbles to the liberated bitumen are essential process steps for bitumen recovery in ore-water slurry-based extraction processes.
FIELD OF THE INVENTION
The present invention relates to processes for extracting bitumen from oil sands.
BACKGROUND OF THE INVENTION
The oil sands deposits of northern Alberta in Canada contain about 142 billion cubic meters (or 890 billion barrels) of bitumen, thus constituting the largest oil sands deposit in the world. In the Athabasca of Alberta, the oil sands deposits are typically composed of (by weight) io about 12% bitumen, 82% to 85% mineral matter (solids) and 3% to 6% water.
Of the solids fraction, the solids smaller than 45 microns in size (i.e., silt and clay) are referred to as fines.
The clay fraction of the fines can be a significant factor in processes for both extraction of bitumen and disposal of oil sands tailings (i.e., residue from primary oil sands processing).
The bitumen content of the Athabasca deposits has been commercially utilized by oil sands ore-water slurry-based extraction processes and thermal in-situ processes and upgraded to synthetic crude oil at a production capacity of over one million barrels per day. In the major bitumen recovery operations in the Athabasca region, bitumen is produced from the surface-mineable oil sands using water-slurry-based extraction processes, in which the oil sands "ore"
(i.e., the raw oil sands material, as excavated from the oil sands deposits) is mixed with hot water to form an ore-water slurry. Asphaltic acids present in bitumen, which contain partly aromatic, oxygen functional groups such as phenolic, carboxylic and sulphonic types, become water-soluble, especially when the ore-water slurry's pH (i.e., a measure of acidity expressed as the minus logarithm of the hydrogen ions concentration: pH = -log [H+]) is slightly over 7, and act as surfactants reducing the surface and interfacial tensions. Reduction of the surface and interfacial tensions of the ore-water slurry system results in the disintegration of the ore structure and liberation of bitumen from the ore. Accordingly, the water-soluble fraction of bitumen asphaltenes plays an important role in the recovery of bitumen from the surface-mineable oil sands ore.
It is know to increased the water-soluble fraction of bitumen by increasing the pH of the oil sands ore-water slurry by the addition of caustic soda (NaOH), soda ash (NaZCO3), or any salt of weak acid and strong base (hydrolysis of which would be basic).
Alternatively, this desirable result can be achieved by modifying the asphaltene molecules contained in bitumen by oxidation, sulfonation and/or sulfoxidation reactions to water soluble surfactants, which reduce the surface and interfacial tensions: see International Application No. PCT/CA2005/001875 (WIPO Pub.
No. WO 2006/060917).
Liberated bitumen has to be recovered from the ore-water slurry by separation methods based on density differences. Bitumen density is very close to the density of water;
consequently, bitumen needs to become effectively "attached" to air bubbles in order for it to be recovered from the ore-water slurry system by means of flotation. However, clay particles present in the ore can become attached to bitumen droplets, thus preventing the desired interaction between bitumen and air bubbles. This undesirable attachment of clay particles to bitumen is promoted by calcium (Ca 2) and magnesium (Mg2+) ions present in the process water.
Another significant factor with respect to bitumen recovery is that the temperature of the ore-water slurry has to be above a critical temperature, above which bitumen becomes mobile enough (i.e., having sufficiently low viscosity) to enfold the air bubble (and thus facilitate flotation). This critical temperature for the Athabasca bitumen is reported by several researchers to be around 32 C.
In summary, liberation of bitumen from oil sands matrix and attachment of air bubbles to the liberated bitumen are essential process steps for bitumen recovery in ore-water slurry-based extraction processes.
BRIEF SUMMARY OF THE INVENTION
In general terms, the present invention is a non-caustic bitumen extraction process, which relates to bitumen recovery in oil sands ore-water slurry based extraction processes by using lime (CaO or Ca(OH)Z) as an additive. The addition of CaO (or Ca(OH)2) lime, in effective dosages, into ore-water slurry has been found to promote the liberation of bitumen from the oil sands matrix, to promote detachment of clay particles from bitumen droplets, and to improve or promote the attachment of bitumen to air bubbles, thus increasing bitumen recovery efficiencies.
The methods of the present invention also improve the release water chemistry and reduce the clay content in the release water by flocculating the clay particles present therein, thus enhancing the release water's suitability for recycling to the extraction process. The methods of the present invention are effective over a wide range of process temperatures, specifically including (but not limited to) the range of 25 C to 85 C.
DESCRIPTION OF THE INVENTION
The methods of present invention use CaO lime (or Ca(OH)Z) at dosages 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. The addition of CaO lime into the ore-water slurry causes the pH of the slurry to increase, in turn causing the asphaltic acids at the bitumen-water interface to become water-soluble. Water-soluble asphaltic acids formed at the bitumen-water interface act as surfactants and eliminate the activity of Ca2+ and MgZ+ ions binding the clay particles and bitumen together.
When CaO lime (or Ca(OH)2) is added to the ore-water slurry, the alkali action (i.e., increased pH due to the introduction of OH' ions) results in an increase in the solubility of asphaltic acids (fraction of bitumen asphaltenes), and clay particles in the slurry react with the Ca2+ and Mg2+ ions. This results in detachment of clay particles from bitumen droplets, and promotes the attachment of bitumen droplets to air bubbles, which in turn promotes bitumen extraction efficiency for reasons previously discussed.
The clay particles detached from the bitumen droplets flocculate within the slurry mixture by ion exchange reactions (specifically: 2Clay-Na + Ca2+ H(Clay)Z-Ca + 2Na+) between the clay and the Ca2+ ions introduced by CaO addition and/or the Caz+ and Mg 2 ions attached to water-soluble asphaltic acids produced by CaO addition. Experimental findings have indicated that any release water recovered from ore-water slurry conditioned with CaO
lime had much lower turbidity (a measure for the number of suspended clay size particles in the water). In fact, addition of CaO lime even at very low dosages introduces additional Ca2+ ions for the clay particle to flocculate, which converts Ca(OH)Z to NaOH (by the ion exchange reaction: 2Clay-Na + Ca(OH)Z H(Clay)2Ca + 2NaOH) during the extraction process. Release water chemistry results indicating low Ca2+ and Mg + concentrations provide evidence that such ion exchange reactions are occurring in addition to chemical reactions forming carbonates (CaCO3 or MgCO3) from bicarbonates (i.e., by the reaction: Ca,Mg(HCO3)Z + Ca(OH)2 H Ca,MgCO3 +
2H20).
Furthermore, carbon dioxide (CO2) contained in the atmosphere will also react with Ca(OH)z lime added into an ore-water slurry, resulting in the precipitation of calcium carbonate (CaCO3) by the reaction: Ca(OH)Z + CO2 H CaCO3 + H20. As a result of this reaction, the pH
of the slurry and/or release water would be reduced as functions of time and temperature, to the range of approximately 8.0 (or even lower).
In laboratory tests of the methods of present invention, CaO lime (or Ca(OH)2) was used as a process aid for bitumen without harming the release water chemistry, because of the above-noted chemical reactions taking place simultaneously. As an example, the process water used for the preparation of oil sands ore-water slurry had the following chemistry: pH
= 8.18, Total Alkalinity (mg CaCO3/L) = 307, HCO3 Alkalinity (mg CaCO3/L) = 307, Na+ = 441 mg/L, Mg +
= 7.8 mg/L, Ca2+ = 7.6 mg/L, Cl- = 171 mg/L, and S042- = 158 mg/L. Extraction tests were performed using a Denver D-12 Flotation Cell apparatus, at 50 C temperature, using ore-water slurry composed of 300 g ore and 360 g process water. When no additive was used:
= bitumen extraction efficiency was measured at 92.3%;
= the froth was composed of 21.6% bitumen, 34.1% water and 45.4% solids; and = the chemistry of the release water was: pH = 8.33, Total Alkalinity (mg CaCO3/L) =
230, HCO3 Alkalinity (mg CaCO3/L) = 230, Na+ = 340 mg/L, Mg2+ = 9.1 mg/L, Ca2+
=
8.4 mg/L, Cl- = 165 mg/L, and S042- = 174 mg/L.
Extraction tests were performed on the same ore-water slurry sample, using the same process water and at the same temperature, and using CaO as a process aid for extraction at a dosage of 60 mg-Ca0 per kg ore, with the following results:
= bitumen extraction efficiency was measured as 96.4 %;
= the froth was composed of 21.5% bitumen, 35.0% water, and 41.7% solids; and = the chemistry of the release water was of pH = 8.52, Total Alkalinity (mg CaCO3/L) =
247, HCO3 Alkalinity (mg CaCO3/L) = 241, Na+ = 338 mg/L, MgZ+ = 10.4 mg/L, Ca2+ =
10.2 mg/L, Cl- = 176 mg/L, and SO42- = 185 mg/L.
Similar results were obtained when the release water recovered from the previous test was used as the process water for the next extraction test. The data presented above illustrate that show that bitumen extraction efficiency is improved by the use of CaO
lime (or Ca(OH)2) as a process aid, without harming the release water chemistry. When CaO is used as a process aid for bitumen extraction, the chemistry of the release water improves; the release water becomes more suitable than the original water for recycling for use in the extraction process.
In summary, the addition of CaO (or Ca(OH)2) into oil sands ore-water slurry systems as a process aid for bitumen extraction results in the following benefits:
= Increased bitumen extraction efficiency (by suppressing bitumen-clay attractions and promoting bitumen-air attachments);
= Promotion of flocculation of clay particles, thereby reducing the amount of suspended clay particles in the release water; and = Improved release water chemistry due to reduction of Ca2+ and Mg1+
concentrations in the release water.
In general terms, the present invention is a non-caustic bitumen extraction process, which relates to bitumen recovery in oil sands ore-water slurry based extraction processes by using lime (CaO or Ca(OH)Z) as an additive. The addition of CaO (or Ca(OH)2) lime, in effective dosages, into ore-water slurry has been found to promote the liberation of bitumen from the oil sands matrix, to promote detachment of clay particles from bitumen droplets, and to improve or promote the attachment of bitumen to air bubbles, thus increasing bitumen recovery efficiencies.
The methods of the present invention also improve the release water chemistry and reduce the clay content in the release water by flocculating the clay particles present therein, thus enhancing the release water's suitability for recycling to the extraction process. The methods of the present invention are effective over a wide range of process temperatures, specifically including (but not limited to) the range of 25 C to 85 C.
DESCRIPTION OF THE INVENTION
The methods of present invention use CaO lime (or Ca(OH)Z) at dosages 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. The addition of CaO lime into the ore-water slurry causes the pH of the slurry to increase, in turn causing the asphaltic acids at the bitumen-water interface to become water-soluble. Water-soluble asphaltic acids formed at the bitumen-water interface act as surfactants and eliminate the activity of Ca2+ and MgZ+ ions binding the clay particles and bitumen together.
When CaO lime (or Ca(OH)2) is added to the ore-water slurry, the alkali action (i.e., increased pH due to the introduction of OH' ions) results in an increase in the solubility of asphaltic acids (fraction of bitumen asphaltenes), and clay particles in the slurry react with the Ca2+ and Mg2+ ions. This results in detachment of clay particles from bitumen droplets, and promotes the attachment of bitumen droplets to air bubbles, which in turn promotes bitumen extraction efficiency for reasons previously discussed.
The clay particles detached from the bitumen droplets flocculate within the slurry mixture by ion exchange reactions (specifically: 2Clay-Na + Ca2+ H(Clay)Z-Ca + 2Na+) between the clay and the Ca2+ ions introduced by CaO addition and/or the Caz+ and Mg 2 ions attached to water-soluble asphaltic acids produced by CaO addition. Experimental findings have indicated that any release water recovered from ore-water slurry conditioned with CaO
lime had much lower turbidity (a measure for the number of suspended clay size particles in the water). In fact, addition of CaO lime even at very low dosages introduces additional Ca2+ ions for the clay particle to flocculate, which converts Ca(OH)Z to NaOH (by the ion exchange reaction: 2Clay-Na + Ca(OH)Z H(Clay)2Ca + 2NaOH) during the extraction process. Release water chemistry results indicating low Ca2+ and Mg + concentrations provide evidence that such ion exchange reactions are occurring in addition to chemical reactions forming carbonates (CaCO3 or MgCO3) from bicarbonates (i.e., by the reaction: Ca,Mg(HCO3)Z + Ca(OH)2 H Ca,MgCO3 +
2H20).
Furthermore, carbon dioxide (CO2) contained in the atmosphere will also react with Ca(OH)z lime added into an ore-water slurry, resulting in the precipitation of calcium carbonate (CaCO3) by the reaction: Ca(OH)Z + CO2 H CaCO3 + H20. As a result of this reaction, the pH
of the slurry and/or release water would be reduced as functions of time and temperature, to the range of approximately 8.0 (or even lower).
In laboratory tests of the methods of present invention, CaO lime (or Ca(OH)2) was used as a process aid for bitumen without harming the release water chemistry, because of the above-noted chemical reactions taking place simultaneously. As an example, the process water used for the preparation of oil sands ore-water slurry had the following chemistry: pH
= 8.18, Total Alkalinity (mg CaCO3/L) = 307, HCO3 Alkalinity (mg CaCO3/L) = 307, Na+ = 441 mg/L, Mg +
= 7.8 mg/L, Ca2+ = 7.6 mg/L, Cl- = 171 mg/L, and S042- = 158 mg/L. Extraction tests were performed using a Denver D-12 Flotation Cell apparatus, at 50 C temperature, using ore-water slurry composed of 300 g ore and 360 g process water. When no additive was used:
= bitumen extraction efficiency was measured at 92.3%;
= the froth was composed of 21.6% bitumen, 34.1% water and 45.4% solids; and = the chemistry of the release water was: pH = 8.33, Total Alkalinity (mg CaCO3/L) =
230, HCO3 Alkalinity (mg CaCO3/L) = 230, Na+ = 340 mg/L, Mg2+ = 9.1 mg/L, Ca2+
=
8.4 mg/L, Cl- = 165 mg/L, and S042- = 174 mg/L.
Extraction tests were performed on the same ore-water slurry sample, using the same process water and at the same temperature, and using CaO as a process aid for extraction at a dosage of 60 mg-Ca0 per kg ore, with the following results:
= bitumen extraction efficiency was measured as 96.4 %;
= the froth was composed of 21.5% bitumen, 35.0% water, and 41.7% solids; and = the chemistry of the release water was of pH = 8.52, Total Alkalinity (mg CaCO3/L) =
247, HCO3 Alkalinity (mg CaCO3/L) = 241, Na+ = 338 mg/L, MgZ+ = 10.4 mg/L, Ca2+ =
10.2 mg/L, Cl- = 176 mg/L, and SO42- = 185 mg/L.
Similar results were obtained when the release water recovered from the previous test was used as the process water for the next extraction test. The data presented above illustrate that show that bitumen extraction efficiency is improved by the use of CaO
lime (or Ca(OH)2) as a process aid, without harming the release water chemistry. When CaO is used as a process aid for bitumen extraction, the chemistry of the release water improves; the release water becomes more suitable than the original water for recycling for use in the extraction process.
In summary, the addition of CaO (or Ca(OH)2) into oil sands ore-water slurry systems as a process aid for bitumen extraction results in the following benefits:
= Increased bitumen extraction efficiency (by suppressing bitumen-clay attractions and promoting bitumen-air attachments);
= Promotion of flocculation of clay particles, thereby reducing the amount of suspended clay particles in the release water; and = Improved release water chemistry due to reduction of Ca2+ and Mg1+
concentrations in the release water.
The dosage of CaO lime addition to oil sands ore-water slurry has to be controlled, since the excessive addition of CaO could result in flocculation of clay with Ca2+, which would result in increase in viscosity and the formation of yield stress. As persons skilled in the art will know, yield stress is a geotechnical property of the ore-water slurry, and is a measure of the shear stress when the shear rate is approaching to zero. Formation of yield stress results in a gel-like fluid property for the ore-water slurry, caused by the clay flocculation by CaZ+
(and/or Mgz+) ions.
Formation of yield stress in oil sands ore-water slurry is undesirable for bitumen extraction (whereas formation of yield stress is desirable for production of non-segregating tailings for the deposition of oil sands tailings as a non-segregating mix). Formation of yield stress can be anticipated for the addition of CaO in dosages of approximately 1,000 mg of CaO per kg ore or higher.
Experiments performed for the present invention suggest that the optimal upper limit of the CaO dosage is in the range of 600 mg per kg (milligrams per kilogram) of ore, based on oil sands ore having the typical composition set out previously in this specification. The CaO
dosage could be higher than 600 mg per kg depending on the ore composition (or, more specifically, the percentage of bitumen, by weight), without deleteriously affecting the release water chemistry. However, the bitumen extraction efficiency would not be sharply reduced if CaO were to be used in excessive amounts.
The practical or desirable upper limit of CaO dosage will also be a function of process water chemistry and ore characteristics (e.g., bitumen properties, mineral type, fines contents, clay type, etc.). Therefore, the use of CaO as a bitumen extraction process aid has a wide open window of CaO dosage for process operators, without negatively affecting bitumen extraction efficiency or release water chemistry. However, tests results have tended to suggest an optimal dosage of CaO lime addition in the range of 30 to 200 mg per kg of ore, and it is to be noted that the lime dosage can be effectively monitored by pH measurement. Although dosages outside this optimal range may be beneficially used in accordance with the principles of the present invention, the dosage of CaO lime addition preferably should not exceed the dosage that would increase the pH of the ore-water slurry to above approximately 9.5.
(and/or Mgz+) ions.
Formation of yield stress in oil sands ore-water slurry is undesirable for bitumen extraction (whereas formation of yield stress is desirable for production of non-segregating tailings for the deposition of oil sands tailings as a non-segregating mix). Formation of yield stress can be anticipated for the addition of CaO in dosages of approximately 1,000 mg of CaO per kg ore or higher.
Experiments performed for the present invention suggest that the optimal upper limit of the CaO dosage is in the range of 600 mg per kg (milligrams per kilogram) of ore, based on oil sands ore having the typical composition set out previously in this specification. The CaO
dosage could be higher than 600 mg per kg depending on the ore composition (or, more specifically, the percentage of bitumen, by weight), without deleteriously affecting the release water chemistry. However, the bitumen extraction efficiency would not be sharply reduced if CaO were to be used in excessive amounts.
The practical or desirable upper limit of CaO dosage will also be a function of process water chemistry and ore characteristics (e.g., bitumen properties, mineral type, fines contents, clay type, etc.). Therefore, the use of CaO as a bitumen extraction process aid has a wide open window of CaO dosage for process operators, without negatively affecting bitumen extraction efficiency or release water chemistry. However, tests results have tended to suggest an optimal dosage of CaO lime addition in the range of 30 to 200 mg per kg of ore, and it is to be noted that the lime dosage can be effectively monitored by pH measurement. Although dosages outside this optimal range may be beneficially used in accordance with the principles of the present invention, the dosage of CaO lime addition preferably should not exceed the dosage that would increase the pH of the ore-water slurry to above approximately 9.5.
Use of the methods of the present invention will prevent or minimize the undesirable accumulation of Na+ ions in recycled release water from the oil sands tailings (i.e., tailings water recycled for use in ore-water slurry), since the present invention does not use any process additives such as NaOH or Na2CO3 or any other sodium salts (i.e., sodium salts of weak acids) for the extraction of bitumen.
The methods of the present invention may also result in significant reduction in the operating temperature of the oil sands ore-water slurry-based extraction processes (depending on the ore grade), thereby reducing thermal energy consumption, COZ emissions, and bitumen production costs.
The methods of the present invention may also be readily adapted for use in conjunction with processes taught in International Application No. PCT/CA2005/001875 (WIPO
Pub. No.
The methods of the present invention may also result in significant reduction in the operating temperature of the oil sands ore-water slurry-based extraction processes (depending on the ore grade), thereby reducing thermal energy consumption, COZ emissions, and bitumen production costs.
The methods of the present invention may also be readily adapted for use in conjunction with processes taught in International Application No. PCT/CA2005/001875 (WIPO
Pub. No.
7). The application of the teachings of both inventions, either concurrently or sequentially, will further promote the liberation of bitumen from the oil sands matrix by promoting the attachment of air bubbles to bitumen droplets, thereby forming a bitumen-rich froth which will float to the surface of the ore-water slurry, thus facilitating bitumen recovery.
The benefits and particulars of the methods of the present invention are further described and summarized below:
1. Addition of CaO lime (or Ca(OH)2) to oil sands ore-water slurries in concentrations as low as 0.05 grams per kilogram of ore improves the efficiency of bitumen extraction in water-slurry based extraction processes by promoting the liberation of bitumen from oil sands matrix and attachment of air bubbles to bitumen.
2. The addition and mixing of CaO (or Ca(OH)Z) into an oil sands ore-water slurry can be effected in a variety of ways, including direct introduction into ore conditioning vessels; ore-water slurry transportation pipelines; primary, secondary, or other separation vessels; and/or into any slurry preparation feed water, including recycle and/or make-up water. Persons skilled in the art of the present invention will readily appreciate that other methods and means for adding and mixing CaO (or Ca(OH)2) into an oil sands ore-water slurry may be devised without departing from the essential principles of the present invention.
3. The addition of CaO lime to oil sands ore-water slurries improves the efficiency of slurry-based bitumen extraction processes by reducing the attachment of clay particles to bitumen, thus promoting liberation of bitumen droplets from the oil sands matrix.
4. The addition of CaO lime to oil sands ore-water slurries improves the attachment of air bubbles to bitumen, thus promoting the flotation of bitumen to the slurry surface in the form of a bitumen-rich froth.
5. The addition of CaO lime to oil sands ore-water slurries improves bitumen extraction efficiency in the temperature range of 25 C to 85 C. Therefore, the present invention may result in the reduction of extraction process temperature to the range of 35 C to 45 C, which results in significant savings in energy consumption and CO2 emissions.
6. The addition of CaO lime to oil sands ore-water slurries reduces the amount of clay particles in the release water, by flocculating the clay particles by ion exchange mechanisms between the clay and Ca2+ and Mg2+ ions.
7. The addition of CaO lime to oil sands ore-water slurries improves the water chemistry of the release water by reducing CaZ+ and MgZ+ concentrations by way of bicarbonate-to-carbonate reactions and by ion exchange reactions between the clay particles and Ca2+
and Mgl+ ions.
The benefits and particulars of the methods of the present invention are further described and summarized below:
1. Addition of CaO lime (or Ca(OH)2) to oil sands ore-water slurries in concentrations as low as 0.05 grams per kilogram of ore improves the efficiency of bitumen extraction in water-slurry based extraction processes by promoting the liberation of bitumen from oil sands matrix and attachment of air bubbles to bitumen.
2. The addition and mixing of CaO (or Ca(OH)Z) into an oil sands ore-water slurry can be effected in a variety of ways, including direct introduction into ore conditioning vessels; ore-water slurry transportation pipelines; primary, secondary, or other separation vessels; and/or into any slurry preparation feed water, including recycle and/or make-up water. Persons skilled in the art of the present invention will readily appreciate that other methods and means for adding and mixing CaO (or Ca(OH)2) into an oil sands ore-water slurry may be devised without departing from the essential principles of the present invention.
3. The addition of CaO lime to oil sands ore-water slurries improves the efficiency of slurry-based bitumen extraction processes by reducing the attachment of clay particles to bitumen, thus promoting liberation of bitumen droplets from the oil sands matrix.
4. The addition of CaO lime to oil sands ore-water slurries improves the attachment of air bubbles to bitumen, thus promoting the flotation of bitumen to the slurry surface in the form of a bitumen-rich froth.
5. The addition of CaO lime to oil sands ore-water slurries improves bitumen extraction efficiency in the temperature range of 25 C to 85 C. Therefore, the present invention may result in the reduction of extraction process temperature to the range of 35 C to 45 C, which results in significant savings in energy consumption and CO2 emissions.
6. The addition of CaO lime to oil sands ore-water slurries reduces the amount of clay particles in the release water, by flocculating the clay particles by ion exchange mechanisms between the clay and Ca2+ and Mg2+ ions.
7. The addition of CaO lime to oil sands ore-water slurries improves the water chemistry of the release water by reducing CaZ+ and MgZ+ concentrations by way of bicarbonate-to-carbonate reactions and by ion exchange reactions between the clay particles and Ca2+
and Mgl+ ions.
8. The methods of the present invention reduce or eliminate the accumulation of Na+ ions in recycled release water from the oil sands tailings, since the present invention does not use any process aid such as NaOH, NaZCOj or any other sodium salts of weak acids for the extraction of bitumen.
9. The Caz+ ions injected into the ore-water slurry by virtue of CaO lime addition in accordance with the present invention also promotes flocculation of clay particles during the disposal of oil sands tailings.
10. Carbon dioxide (CO2) contained in the atmosphere would also react with Ca(OH)2 lime added into ore-water slurry as an additive to improve bitumen extraction, which result in the precipitation of calcium carbonate, with consequent reduction of the pH of the slurry and/or release water to as low as or lower than 8Ø
11. The methods of the present invention can be readily adapted for cooperative use in association with other processes directed to bitumen recovery from oil sands ore, including but not limited to the processes taught by the following patent applications:
1. International Application No. PCT/CA2005/001875 (WO 2006/060917); and 2. Canadian Patent Applications No. 2,188,064 and No. 2,522,031 (directed specifically to the production of non-segregating oil sands tailings using CaO or CaO+CO2).
Although the methods of the present invention have been described with specific reference to the use of CaO lime (or Ca(OH)Z) as a process additive, it is also to be noted that the methods of the invention can be readily adapted to use oxides (or hydroxides) of other alkaline earth metals (for example, beryllium, magnesium, strontium, and barium) as alternatives to CaO
lime (or Ca(OH)Z), and all such alternative methods and usages are intended to come within the scope of the present invention.
It will be readily appreciated by those skilled in the art that various modifications of the present invention may be devised without departing from the essential concepts and principles of the invention, and all such modifications are intended to come within the scope of the present invention and the claims appended hereto. It is to be especially understood that the invention is not intended to be limited to illustrated embodiments, and that the substitution of a variant of a claimed element or feature, without any substantial resultant change in the working of the invention, will not constitute a departure from the scope of the invention.
In this patent document, the word "comprising" is used in its non-limiting sense to mean that items following that word are included, but items not specifically mentioned are not excluded. A reference to an element by the indefinite article "a" does not exclude the possibility that more than one of the element is present, unless the context clearly requires that there be one and only one such element.
1. International Application No. PCT/CA2005/001875 (WO 2006/060917); and 2. Canadian Patent Applications No. 2,188,064 and No. 2,522,031 (directed specifically to the production of non-segregating oil sands tailings using CaO or CaO+CO2).
Although the methods of the present invention have been described with specific reference to the use of CaO lime (or Ca(OH)Z) as a process additive, it is also to be noted that the methods of the invention can be readily adapted to use oxides (or hydroxides) of other alkaline earth metals (for example, beryllium, magnesium, strontium, and barium) as alternatives to CaO
lime (or Ca(OH)Z), and all such alternative methods and usages are intended to come within the scope of the present invention.
It will be readily appreciated by those skilled in the art that various modifications of the present invention may be devised without departing from the essential concepts and principles of the invention, and all such modifications are intended to come within the scope of the present invention and the claims appended hereto. It is to be especially understood that the invention is not intended to be limited to illustrated embodiments, and that the substitution of a variant of a claimed element or feature, without any substantial resultant change in the working of the invention, will not constitute a departure from the scope of the invention.
In this patent document, the word "comprising" is used in its non-limiting sense to mean that items following that word are included, but items not specifically mentioned are not excluded. A reference to an element by the indefinite article "a" does not exclude the possibility that more than one of the element is present, unless the context clearly requires that there be one and only one such element.
Claims (2)
1. The use of CaO lime (or Ca(OH)2) as an additive oil sands ore-water slurry to enhance the efficiency of bitumen recovery from the oil sands ore.
2. A method for enhancing the efficiency of bitumen recovery from oil sands ore, said method comprising the step of adding CaO lime (or Ca(OH)2) to an oil sands ore-water slurry prior to or during the operation of slurry-based bitumen extraction processes.
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| CA2581586A CA2581586C (en) | 2006-03-15 | 2007-03-14 | Extraction of bitumen from oil sands using lime |
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| Application Number | Priority Date | Filing Date | Title |
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| CA2,541,273 | 2006-03-15 | ||
| CA2541273 | 2006-03-15 | ||
| CA2581586A CA2581586C (en) | 2006-03-15 | 2007-03-14 | Extraction of bitumen from oil sands using lime |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US9011972B2 (en) | 2008-10-29 | 2015-04-21 | E I Du Pont De Nemours And Company | Treatment of tailings streams |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US9011972B2 (en) | 2008-10-29 | 2015-04-21 | E I Du Pont De Nemours And Company | Treatment of tailings streams |
| US9481799B2 (en) | 2008-10-29 | 2016-11-01 | The Chemours Company Fc, Llc | Treatment of tailings streams |
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