CA3102651A1 - Small-scale bitumen extraction processes and plants - Google Patents
Small-scale bitumen extraction processes and plants Download PDFInfo
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- CA3102651A1 CA3102651A1 CA3102651A CA3102651A CA3102651A1 CA 3102651 A1 CA3102651 A1 CA 3102651A1 CA 3102651 A CA3102651 A CA 3102651A CA 3102651 A CA3102651 A CA 3102651A CA 3102651 A1 CA3102651 A1 CA 3102651A1
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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
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- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F11/00—Treatment of sludge; Devices therefor
- C02F11/12—Treatment of sludge; Devices therefor by de-watering, drying or thickening
- C02F11/14—Treatment of sludge; Devices therefor by de-watering, drying or thickening with addition of chemical agents
- C02F11/143—Treatment of sludge; Devices therefor by de-watering, drying or thickening with addition of chemical agents using inorganic substances
- C02F11/145—Treatment of sludge; Devices therefor by de-watering, drying or thickening with addition of chemical agents using inorganic substances using calcium compounds
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- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F2101/00—Nature of the contaminant
- C02F2101/30—Organic compounds
- C02F2101/32—Hydrocarbons, e.g. oil
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- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F2103/00—Nature of the water, waste water, sewage or sludge to be treated
- C02F2103/10—Nature of the water, waste water, sewage or sludge to be treated from quarries or from mining activities
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Abstract
ABSTRACT
The use of calcium oxide (Ca0) instead of sodium hydroxide (Na0H) as a process additive in the ore-conditioning stage of a slurry-based process for extracting bitumen from oil sands ore results in reduced retention times for both the ore-conditioning stage and the bitumen froth formation stage of the bitumen extraction process. These reduced retention times enable the use of smaller process vessels, thereby making it feasible to carry out both of these process phases in small-scale processing facilities located close to oil sands deposits, so that excavated oil sands ore only has to be hauled to the nearby small-scale facilities, and only the bitumen-rich froth produced at the small-scale facilities needs to be conveyed to the main bitumen extraction plant, thus reducing ore transportation costs.
Date Recue/Date Received 2020-12-14
The use of calcium oxide (Ca0) instead of sodium hydroxide (Na0H) as a process additive in the ore-conditioning stage of a slurry-based process for extracting bitumen from oil sands ore results in reduced retention times for both the ore-conditioning stage and the bitumen froth formation stage of the bitumen extraction process. These reduced retention times enable the use of smaller process vessels, thereby making it feasible to carry out both of these process phases in small-scale processing facilities located close to oil sands deposits, so that excavated oil sands ore only has to be hauled to the nearby small-scale facilities, and only the bitumen-rich froth produced at the small-scale facilities needs to be conveyed to the main bitumen extraction plant, thus reducing ore transportation costs.
Date Recue/Date Received 2020-12-14
Description
SMALL-SCALE BITUMEN EXTRACTION PROCESSES AND PLANTS
FIELD
The present disclosure relates in general to oil sands ore-water slurry-based bitumen extraction processes, and methods for improving the efficiency of such processes and ancillary operations, including operations for transportation of oil sands ore from mines to oil sands plants.
BACKGROUND
The oil sands deposits in the Athabasca region of Alberta, Canada contain about 142 billion cubic meters (or 890 billion barrels) of heavy hydrocarbons, in the form of bitumen, constituting the third largest hydrocarbon deposit in the world.
These oil sands are composed of about 12% bitumen, 82% to 85% mineral matter (solids), and 3%
to 6%
water (by weight). The fraction of the solids smaller than 45 microns in size (1 micron =
0.001 millimeter) is commonly referred to as "fines", made up of silt and clay particles.
The clay fraction of the fines (i.e., smaller than 2 microns in size) is an important factor in both bitumen extraction processes and oil sands tailings disposal processes.
Bitumen been commercially produced from surface-mined oil sands ore using ore-water slurry-based extraction processes since 1967. The current bitumen production capacity in the Alberta oil sands is about 1.3 billion barrels per day, and it is predicted to increase to more than 2.0 billion barrels per day over the next decade with the commissioning of new extraction plants and increases in the capacity of existing plants.
Extraction of bitumen from oil sands ore in slurry-based extraction processes typically involves three basic processes (schematically depicted in Figure 1 herein):
= Liberation of bitumen from the oil sands ore matrix;
= Coalescence of small bitumen droplets in the slurry to form larger droplets; and = Aeration to produce a bitumen-rich froth from which the bitumen can be recovered using flotation methods.
Date Recue/Date Received 2020-12-14 The Clark Hot Water Extraction (CHWE) process, which was developed in the 1930s, is commonly used in commercial slurry-based bitumen extraction plants.
The CHWE process involves preparation of an ore-water slurry containing approximately equal amounts (by mass) of oil sands ore and water, with the water (also referred to as process water) typically being at a temperature of about 50-85 degrees Celsius. Caustic sodium hydroxide (NaOH) is added to the slurry during this stage to increase its pH to a value between 8.1 and 9.0 (pH being a measure of acidity defined by the equation pH = -log [WI, where [H-1 is the molar hydrogen ion concentration). This increase in pH
results in activation of asphaltic acids naturally present in the bitumen to produce surfactant species that reduce water surface tension and bitumen/water interfacial tension (abbreviated herein as "B/W WI.") in the water film between sand particles and bitumen in the extraction process slurry. This reduction of B/W IFT in the extraction process slurry has the beneficial effect of promoting the liberation of bitumen from the oil sands ore matrix, in accordance with Figure 1.
However, because the CHWE process reduces B/W IFT, also promotes hydrophilicity or wettability of bitumen droplets, and thus has the undesirable effect of suppressing coalescence of bitumen droplets (which is desirable because larger bitumen droplets resulting from coalescence can be extracted more efficiently than smaller droplets) and aeration kinetics, thereby reducing bitumen extraction efficiency. For these reasons, the CHWE process requires longer retention times and therefore very large process vessels (for example, primary reactor vessels in CHWE plants may be 40 meters or more in diameter). These requirements entail correspondingly large capital costs and operating costs.
Furthermore, because the CHWE process reduces water surface tension, it promotes dispersion of silt-size and clay-size particles in the extraction process slurry, produces tailings effluents with poor settling and consolidation properties, and results in production of mature fluid fine tailings (or mature FFT¨also called mature fine tailings or MFT).
FIELD
The present disclosure relates in general to oil sands ore-water slurry-based bitumen extraction processes, and methods for improving the efficiency of such processes and ancillary operations, including operations for transportation of oil sands ore from mines to oil sands plants.
BACKGROUND
The oil sands deposits in the Athabasca region of Alberta, Canada contain about 142 billion cubic meters (or 890 billion barrels) of heavy hydrocarbons, in the form of bitumen, constituting the third largest hydrocarbon deposit in the world.
These oil sands are composed of about 12% bitumen, 82% to 85% mineral matter (solids), and 3%
to 6%
water (by weight). The fraction of the solids smaller than 45 microns in size (1 micron =
0.001 millimeter) is commonly referred to as "fines", made up of silt and clay particles.
The clay fraction of the fines (i.e., smaller than 2 microns in size) is an important factor in both bitumen extraction processes and oil sands tailings disposal processes.
Bitumen been commercially produced from surface-mined oil sands ore using ore-water slurry-based extraction processes since 1967. The current bitumen production capacity in the Alberta oil sands is about 1.3 billion barrels per day, and it is predicted to increase to more than 2.0 billion barrels per day over the next decade with the commissioning of new extraction plants and increases in the capacity of existing plants.
Extraction of bitumen from oil sands ore in slurry-based extraction processes typically involves three basic processes (schematically depicted in Figure 1 herein):
= Liberation of bitumen from the oil sands ore matrix;
= Coalescence of small bitumen droplets in the slurry to form larger droplets; and = Aeration to produce a bitumen-rich froth from which the bitumen can be recovered using flotation methods.
Date Recue/Date Received 2020-12-14 The Clark Hot Water Extraction (CHWE) process, which was developed in the 1930s, is commonly used in commercial slurry-based bitumen extraction plants.
The CHWE process involves preparation of an ore-water slurry containing approximately equal amounts (by mass) of oil sands ore and water, with the water (also referred to as process water) typically being at a temperature of about 50-85 degrees Celsius. Caustic sodium hydroxide (NaOH) is added to the slurry during this stage to increase its pH to a value between 8.1 and 9.0 (pH being a measure of acidity defined by the equation pH = -log [WI, where [H-1 is the molar hydrogen ion concentration). This increase in pH
results in activation of asphaltic acids naturally present in the bitumen to produce surfactant species that reduce water surface tension and bitumen/water interfacial tension (abbreviated herein as "B/W WI.") in the water film between sand particles and bitumen in the extraction process slurry. This reduction of B/W IFT in the extraction process slurry has the beneficial effect of promoting the liberation of bitumen from the oil sands ore matrix, in accordance with Figure 1.
However, because the CHWE process reduces B/W IFT, also promotes hydrophilicity or wettability of bitumen droplets, and thus has the undesirable effect of suppressing coalescence of bitumen droplets (which is desirable because larger bitumen droplets resulting from coalescence can be extracted more efficiently than smaller droplets) and aeration kinetics, thereby reducing bitumen extraction efficiency. For these reasons, the CHWE process requires longer retention times and therefore very large process vessels (for example, primary reactor vessels in CHWE plants may be 40 meters or more in diameter). These requirements entail correspondingly large capital costs and operating costs.
Furthermore, because the CHWE process reduces water surface tension, it promotes dispersion of silt-size and clay-size particles in the extraction process slurry, produces tailings effluents with poor settling and consolidation properties, and results in production of mature fluid fine tailings (or mature FFT¨also called mature fine tailings or MFT).
- 2 -Date Recue/Date Received 2020-12-14 Existing bitumen extraction plants have been built at considerable distances from the oil sands deposits that supply them with oil sands ore. In some operations, the mined oil sands ore (typically containing about 82% to 85% solids (sand and fines) and only about 12% bitumen) is transported from the mine site by truck to the extraction plant, where the oil sands ore-water slurry is then prepared. In other operations, the oil sands ore-water slurry is prepared at or close to the mine site and hydraulically conveyed to the extraction plant by pipeline, thus achieving some efficiencies over trucking the ore to the extraction plant. In each of these scenarios, large masses of sand are being conveyed considerable distances and at considerable cost, only to be disposed of at an early stage of the bitumen extraction process ¨ i.e., the larger sand particles that typically make up at least 80% of the solids fraction of oil sands ore settle fairly quickly out of the ore-water slurry during the initial bitumen liberation stage of the extraction process, while the fines fraction (silt and clay particles) remains suspended in the slurry.
For the foregoing reasons, there is a need for slurry-based bitumen extraction processes that avoid or reduce undesirable effects resulting from treatment of oil sands ore-water slurries with NaOH in conventional slurry-based bitumen extraction processes.
There is also a need for means and methods for reducing the capital costs and operational costs associated with transportation of oil sands ore (in either as-excavated form or slurried form) from oil sands mine sites to bitumen extraction plants.
BRIEF SUMMARY
The present disclosure teaches slurry-based bitumen extraction processes that make it possible to use comparatively small-scale oil sands processing plants located comparatively close to oil sands deposits to produce bitumen-rich extraction froth, which can be transported by pipeline to new or existing oil sands plants where the bitumen will be extracted from the froth. This will result in greatly reduced ore transportation costs, because the as-excavated oil sands ore only has to be hauled to the small-scale processing plants rather than all the way to a conventional bitumen extraction plant.
Costs are also greatly reduced for operations that transport oil sands ore from the mine site to the
For the foregoing reasons, there is a need for slurry-based bitumen extraction processes that avoid or reduce undesirable effects resulting from treatment of oil sands ore-water slurries with NaOH in conventional slurry-based bitumen extraction processes.
There is also a need for means and methods for reducing the capital costs and operational costs associated with transportation of oil sands ore (in either as-excavated form or slurried form) from oil sands mine sites to bitumen extraction plants.
BRIEF SUMMARY
The present disclosure teaches slurry-based bitumen extraction processes that make it possible to use comparatively small-scale oil sands processing plants located comparatively close to oil sands deposits to produce bitumen-rich extraction froth, which can be transported by pipeline to new or existing oil sands plants where the bitumen will be extracted from the froth. This will result in greatly reduced ore transportation costs, because the as-excavated oil sands ore only has to be hauled to the small-scale processing plants rather than all the way to a conventional bitumen extraction plant.
Costs are also greatly reduced for operations that transport oil sands ore from the mine site to the
- 3 -Date Recue/Date Received 2020-12-14 bitumen extraction plant, because most of the sand in the oil sands ore will have been removed at the small-scale plant. Therefore, the bitumen content of the frothed slurry piped to the main plant will be much higher than the bitumen content of slurried ore.
These benefits are achieved by combining both the bitumen separation stage and the aeration/froth production stage in the small-scale bitumen processing plants (which could be mobile plants), with lime (calcium oxide, or CaO) or hydrated lime (calcium hydroxide, or Ca(OH)2) being used as a process additive in the bitumen separation stage instead of sodium hydroxide (NaOH) as in the CHWE process. Unique chemical properties provided by CaO in aqueous environments include:
= provision of hydroxyl ions (OH), which increase the pH of the oil sands ore-water slurry (like NaOH does); and = provision of calcium ions (Ca2 ), which simultaneously react with the active species in the slurry, such as clays, bicarbonates (HCO3), bitumen, and water-soluble naphthenates.
The water-soluble naphthenates are surfactants that reduce water surface tension, but the reaction of the calcium ions with the naphthenates reduces their surfactant activity and thus increases bitumen/water interfacial tension (B/W IFT) in the oil sands ore-water slurry, therefore promoting coalescence and aeration of bitumen droplets (instead of suppressing bitumen coalescence and aeration of bitumen droplets like NaOH
does). For this reason, the retention time for the bitumen liberation stage would be significantly less than the retention time for the CHWE process, which makes it possible to used smaller process vessels for a given bitumen production rate. This is one of the reasons why the use of CaO makes it feasible for the bitumen liberation stage to be carried out in smaller plant facilities.
The increase in B/W IFI due to the reaction of calcium ions with naphthenates in the slurry also promotes attraction of air bubbles to bitumen droplets in the slurry, in accordance with Figure 1. Therefore, the formation of bitumen-rich froth during the aeration stage is more efficient than in extraction processes using NaOH, thus making it feasible to use smaller process vessels for the aeration/flotation stage for a given bitumen
These benefits are achieved by combining both the bitumen separation stage and the aeration/froth production stage in the small-scale bitumen processing plants (which could be mobile plants), with lime (calcium oxide, or CaO) or hydrated lime (calcium hydroxide, or Ca(OH)2) being used as a process additive in the bitumen separation stage instead of sodium hydroxide (NaOH) as in the CHWE process. Unique chemical properties provided by CaO in aqueous environments include:
= provision of hydroxyl ions (OH), which increase the pH of the oil sands ore-water slurry (like NaOH does); and = provision of calcium ions (Ca2 ), which simultaneously react with the active species in the slurry, such as clays, bicarbonates (HCO3), bitumen, and water-soluble naphthenates.
The water-soluble naphthenates are surfactants that reduce water surface tension, but the reaction of the calcium ions with the naphthenates reduces their surfactant activity and thus increases bitumen/water interfacial tension (B/W IFT) in the oil sands ore-water slurry, therefore promoting coalescence and aeration of bitumen droplets (instead of suppressing bitumen coalescence and aeration of bitumen droplets like NaOH
does). For this reason, the retention time for the bitumen liberation stage would be significantly less than the retention time for the CHWE process, which makes it possible to used smaller process vessels for a given bitumen production rate. This is one of the reasons why the use of CaO makes it feasible for the bitumen liberation stage to be carried out in smaller plant facilities.
The increase in B/W IFI due to the reaction of calcium ions with naphthenates in the slurry also promotes attraction of air bubbles to bitumen droplets in the slurry, in accordance with Figure 1. Therefore, the formation of bitumen-rich froth during the aeration stage is more efficient than in extraction processes using NaOH, thus making it feasible to use smaller process vessels for the aeration/flotation stage for a given bitumen
- 4 -Date Recue/Date Received 2020-12-14 production rate, and for the aeration/flotation stage to be carried out in smaller plant facilities.
Accordingly, methods and processes in accordance with the present disclosure take advantage of the beneficial effects of using lime (CaO) as an extraction process additive in slurry-based bitumen extraction processes to provide higher bitumen recovery efficiency, faster extraction process kinetics, and tailings with improved geotechnical characteristics without harmful effects on process water chemistry. These benefits make it feasible for both primary (bitumen liberation) and secondary (froth production) stages of slurry-based bitumen extraction processes to be carried out in small-scale facilities close to the oil sands deposits, and thus significantly reducing capital costs and operating costs associated with transportation of oil sands ore to the main extraction plants.
In one aspect, the present disclosure teaches a method for processing oil sands ore by treating an oil sands ore-water slurry with calcium oxide (CaO) at dosage between 250 to 400 parts CaO per million parts oil sands ore by mass, wherein the slurry is prepared by mixing approximately equal masses of oil sands ore and process water, and wherein the temperature of the process water is about 50 to 60 degrees Celsius. The slurry may be conditioned by gentle agitation or stirring to achieve liberation of bitumen from the oil sands ore matrix, and to separate substantially bitumen-free sand from the slurry. The CaO may be added in the form of either quicklime (CaO) or hydrated lime (Ca0H2).
This may be referred to as the first (or ore conditioning) stage of the ore processing method.
The oil sands ore processing method may include the further step of generating a bitumen-rich froth by injecting air into the conditioned ore-water slurry produced by the ore conditioning stage (i.e., the slurry that remains after separation and removal of sand from the slurry). The resultant bitumen-rich froth will typically contain over 50%
bitumen and less than about 15% solids by weight. The generation of bitumen-rich froth may be referred to as the second (or froth production) stage of the ore processing method.
Accordingly, methods and processes in accordance with the present disclosure take advantage of the beneficial effects of using lime (CaO) as an extraction process additive in slurry-based bitumen extraction processes to provide higher bitumen recovery efficiency, faster extraction process kinetics, and tailings with improved geotechnical characteristics without harmful effects on process water chemistry. These benefits make it feasible for both primary (bitumen liberation) and secondary (froth production) stages of slurry-based bitumen extraction processes to be carried out in small-scale facilities close to the oil sands deposits, and thus significantly reducing capital costs and operating costs associated with transportation of oil sands ore to the main extraction plants.
In one aspect, the present disclosure teaches a method for processing oil sands ore by treating an oil sands ore-water slurry with calcium oxide (CaO) at dosage between 250 to 400 parts CaO per million parts oil sands ore by mass, wherein the slurry is prepared by mixing approximately equal masses of oil sands ore and process water, and wherein the temperature of the process water is about 50 to 60 degrees Celsius. The slurry may be conditioned by gentle agitation or stirring to achieve liberation of bitumen from the oil sands ore matrix, and to separate substantially bitumen-free sand from the slurry. The CaO may be added in the form of either quicklime (CaO) or hydrated lime (Ca0H2).
This may be referred to as the first (or ore conditioning) stage of the ore processing method.
The oil sands ore processing method may include the further step of generating a bitumen-rich froth by injecting air into the conditioned ore-water slurry produced by the ore conditioning stage (i.e., the slurry that remains after separation and removal of sand from the slurry). The resultant bitumen-rich froth will typically contain over 50%
bitumen and less than about 15% solids by weight. The generation of bitumen-rich froth may be referred to as the second (or froth production) stage of the ore processing method.
- 5 -Date Recue/Date Received 2020-12-14 Accordingly, this method effectively combines the primary and secondary stages of conventional bitumen extraction processes, by introducing air in the ore-water slurry produced in the ore conditioning stage.
The first and second stages of the ore processing method may be carried out in small-scale extraction plants built at locations remote from the main bitumen extraction plant, such as at location adjacents to or reasonably close to the mine site where the oil sands ore is being excavated. The bitumen-rich froth may be transported by pipeline to the main extraction plant by pipeline.
Tailings effluents discharged from the ore conditioning and froth production process vessels may be combined and disposed of as non-segregating tailings (NST) material, also using CaO as an additive in tailings treatment processes or using conventional tailings management methods.
BRIEF DESCRIPTION OF THE DRAWING
Embodiments will now be described with reference to the accompanying Figure 1, which conceptually illustrates basic processes involved in extracting bitumen from oil sands ore, and specifically illustrating that:
= a decrease in bitumen/water interfacial tension (B/W JET) in the water film between sand particles and bitumen in an oil sands ore-water slurry promotes liberation of bitumen from the sand;
= an increase in B/W IFT promotes coalescence of bitumen droplets in the slurry; and = an increase in B/WIFI also promotes attachment of air bubbles to bitumen droplets in the slurry and thus promotes production of bitumen-rich froth.
DESCRIPTION
Examples of the use of lime (CaO) as a process additive for different purposes in the oil sands industry include Canadian Patent Nos. 2,188,064 and 2,522,031 (for NST
production), Canadian Patent No. 2,581,586 and U.S. Patent No. 7,931,800 (for bitumen
The first and second stages of the ore processing method may be carried out in small-scale extraction plants built at locations remote from the main bitumen extraction plant, such as at location adjacents to or reasonably close to the mine site where the oil sands ore is being excavated. The bitumen-rich froth may be transported by pipeline to the main extraction plant by pipeline.
Tailings effluents discharged from the ore conditioning and froth production process vessels may be combined and disposed of as non-segregating tailings (NST) material, also using CaO as an additive in tailings treatment processes or using conventional tailings management methods.
BRIEF DESCRIPTION OF THE DRAWING
Embodiments will now be described with reference to the accompanying Figure 1, which conceptually illustrates basic processes involved in extracting bitumen from oil sands ore, and specifically illustrating that:
= a decrease in bitumen/water interfacial tension (B/W JET) in the water film between sand particles and bitumen in an oil sands ore-water slurry promotes liberation of bitumen from the sand;
= an increase in B/W IFT promotes coalescence of bitumen droplets in the slurry; and = an increase in B/WIFI also promotes attachment of air bubbles to bitumen droplets in the slurry and thus promotes production of bitumen-rich froth.
DESCRIPTION
Examples of the use of lime (CaO) as a process additive for different purposes in the oil sands industry include Canadian Patent Nos. 2,188,064 and 2,522,031 (for NST
production), Canadian Patent No. 2,581,586 and U.S. Patent No. 7,931,800 (for bitumen
- 6 -Date Recue/Date Received 2020-12-14 extraction), Canadian Patent Application No. 2,840,675 (for destabilization of bitumen-water emulsions), and Canadian Patent Application No. 2,977,524 (for dewatering of existing mature FF1 inventories).
In one embodiment of an oil sands ore processing method in accordance with the present disclosure, an oil sands ore-water slurry is prepared by blending approximately of oil sands ore and process water, and treating this ore-water slurry with CaO
at a dosage sufficient to maintain the pH of the slurry within the range of about 8.0 to about 8.4. By way of non-limiting example, a dosage of about 300 milligrams of CaO per kilogram of oil sands ore (i.e., about 300 parts per million by mass) may be effective in many cases to maintain the slurry pH within this range; however, the appropriate dosage to maintain this pH range in any given case may be higher than or less than 300 ppm, depending on variables including by not limited to properties of the ore and the process water.
The increase in slurry pH resulting from CaO addition reduces bitumen-water interfacial tension (B/W IFT) in the water film between the sand grains and bitumen by generating surfactant species from bitumen asphaltenes, and promotes liberation of bitumen from the oil sands ore matrix, as depicted in Figure 1. In this sense, therefore, present invention and CHWE process are based on the same bitumen liberation mechanism, by the increase in the ore-water slurry pH.
Calcium ions (Ca2 ) present in the slurry due to the addition of CaO react with water-soluble naphthenates in the slurry so as to reduce the surfactant activities of these species and increases water surface tension and B/W IFT. The increase in water surface tension suppresses the dispersion of silt-size and clay-size particles in the slurry. The increase in B/W IFT reduces water wettability of bitumen droplets in the slurry, thereby promoting coalescence of bitumen droplets and attachment of air bubbles to the bitumen droplets, thereby increasing bitumen recovery efficiency and improving overall extraction process kinetics. Therefore, bitumen extraction process using CaO as an extraction process additive require shorter retention times and smaller process vessels.
In one embodiment of an oil sands ore processing method in accordance with the present disclosure, an oil sands ore-water slurry is prepared by blending approximately of oil sands ore and process water, and treating this ore-water slurry with CaO
at a dosage sufficient to maintain the pH of the slurry within the range of about 8.0 to about 8.4. By way of non-limiting example, a dosage of about 300 milligrams of CaO per kilogram of oil sands ore (i.e., about 300 parts per million by mass) may be effective in many cases to maintain the slurry pH within this range; however, the appropriate dosage to maintain this pH range in any given case may be higher than or less than 300 ppm, depending on variables including by not limited to properties of the ore and the process water.
The increase in slurry pH resulting from CaO addition reduces bitumen-water interfacial tension (B/W IFT) in the water film between the sand grains and bitumen by generating surfactant species from bitumen asphaltenes, and promotes liberation of bitumen from the oil sands ore matrix, as depicted in Figure 1. In this sense, therefore, present invention and CHWE process are based on the same bitumen liberation mechanism, by the increase in the ore-water slurry pH.
Calcium ions (Ca2 ) present in the slurry due to the addition of CaO react with water-soluble naphthenates in the slurry so as to reduce the surfactant activities of these species and increases water surface tension and B/W IFT. The increase in water surface tension suppresses the dispersion of silt-size and clay-size particles in the slurry. The increase in B/W IFT reduces water wettability of bitumen droplets in the slurry, thereby promoting coalescence of bitumen droplets and attachment of air bubbles to the bitumen droplets, thereby increasing bitumen recovery efficiency and improving overall extraction process kinetics. Therefore, bitumen extraction process using CaO as an extraction process additive require shorter retention times and smaller process vessels.
- 7 -Date Recue/Date Received 2020-12-14 As well, chemical reaction between calcium ions and clay particles in the slurry causes coagulation of the clay particles and suppresses attraction between the clay particles and water, thus reducing the dispersion of clay particles in the slurry, which is beneficial for management of the tailings effluent discharged from the bitumen extraction plant.
In methods in accordance with the present disclosure, an oil sands ore-water slurry is prepared as described above, followed by a two-stage bitumen extraction process as follows:
(1) ore conditioning by adjusting the extraction process slurry pH to about
In methods in accordance with the present disclosure, an oil sands ore-water slurry is prepared as described above, followed by a two-stage bitumen extraction process as follows:
(1) ore conditioning by adjusting the extraction process slurry pH to about
8.0 to about 8.4 by addition of CaO, to promote liberation of bitumen from the oil sands matrix and separation of most of the solids from the extraction process slurry; and (2) formation of a bitumen extraction froth by air injection or flotation processes, while maintaining the extraction process slurry pH between about 8.0 and about 8.4 with addition of CaO as necessary.
In essence, methods in accordance with the present disclosure combine the primary and secondary extraction steps of the CWHE process into a single step, by using CaO as an additive and injecting air into sufficiently conditioned and de-sanded oil sands-ore water slurry. Processing plants using these methods would require shorter retention times to produce the bitumen-rich extraction froth, and therefore would require smaller process vessels and would have lower capital costs and operating costs than conventional slurry-based bitumen extraction plants. Accordingly, such plants could be comparatively small in scale, making them feasible at locations closer to the oil sands ore mining sites.
Because these methods use CaO as an extraction process additive, they would produce tailings effluent with improved settling and consolidation properties, and would eliminate or mitigate increases in the concentration of sodium ions (Nat) in the process water caused by CHWE process. The tailings produced from small-scale plants using these methods can deposited as a non-segregating tailings (NST) material or by implementing existing tailings management practices.
Date Recue/Date Received 2020-12-14 Experimental Observations It has been experimentally validated by laboratory-scale bitumen extraction tests using Denver Flotation apparatus that when NaOH is used as an extraction process additive (i.e., per the CHWE process), the extraction froth composition in terms of bitumen-to-solids (B/S) mass ratio is weakly dependent on the oil sands ore-water slurry conditioning retention time. However, when CaO is used as an extraction process additive to produce a slurry pH range similar to the slurry pH for the CHWE
process, the B/S ratio of the extraction froth increases with increased slurry conditioning retention time.
Results from experimental tests using a high-grade oil sands ore, and corresponding water chemistry data, are presented in Tables 1 and 2 respectively (below):
Primary Froth Secondary Froth Total Bitumen Bitumen Bitumen Recovery B/S Recovery B/S Recovery B/S
Additive (%) Ratio (%) Ratio (%) Ratio CaO 46.34 3.70 48.51 0.93 94.85 2.17 CaO(*) 64.91 3.70 30.11 0.90 95.02 2.68 NaOH 61.88 4.55 35.81 1.37 97.69 3.30 (*) 10 minutes conditioning retention time _____________________ B/S: Bitumen-to-Solids mass ratio Table 1 ¨ Bitumen extraction tests with high-grade ore EC Alkalinity (mg-CaCO3/L) Cations (mOL) Anions (mg/L) Additive pH (mS/cm) Total CO3- HCO3- Na" Mg2+ Ca2+ Cl- S042-PW 8.7 1.80 288 14 274 340 13 17 179 CaO 8.4 1.77 229 2 227 334 10 17 187 CaO(*) 8.5 1.76 241 8 233 338 11 20 185 NaOH 8.8 1.90 298 26 272 384 _ 5 6 184 247 (*) 10 minutes conditioning retention time B/S: Bitumen-to-Solids mass ratio Table 2¨ Water chemistry, bitumen extraction tests with high-grade ore
In essence, methods in accordance with the present disclosure combine the primary and secondary extraction steps of the CWHE process into a single step, by using CaO as an additive and injecting air into sufficiently conditioned and de-sanded oil sands-ore water slurry. Processing plants using these methods would require shorter retention times to produce the bitumen-rich extraction froth, and therefore would require smaller process vessels and would have lower capital costs and operating costs than conventional slurry-based bitumen extraction plants. Accordingly, such plants could be comparatively small in scale, making them feasible at locations closer to the oil sands ore mining sites.
Because these methods use CaO as an extraction process additive, they would produce tailings effluent with improved settling and consolidation properties, and would eliminate or mitigate increases in the concentration of sodium ions (Nat) in the process water caused by CHWE process. The tailings produced from small-scale plants using these methods can deposited as a non-segregating tailings (NST) material or by implementing existing tailings management practices.
Date Recue/Date Received 2020-12-14 Experimental Observations It has been experimentally validated by laboratory-scale bitumen extraction tests using Denver Flotation apparatus that when NaOH is used as an extraction process additive (i.e., per the CHWE process), the extraction froth composition in terms of bitumen-to-solids (B/S) mass ratio is weakly dependent on the oil sands ore-water slurry conditioning retention time. However, when CaO is used as an extraction process additive to produce a slurry pH range similar to the slurry pH for the CHWE
process, the B/S ratio of the extraction froth increases with increased slurry conditioning retention time.
Results from experimental tests using a high-grade oil sands ore, and corresponding water chemistry data, are presented in Tables 1 and 2 respectively (below):
Primary Froth Secondary Froth Total Bitumen Bitumen Bitumen Recovery B/S Recovery B/S Recovery B/S
Additive (%) Ratio (%) Ratio (%) Ratio CaO 46.34 3.70 48.51 0.93 94.85 2.17 CaO(*) 64.91 3.70 30.11 0.90 95.02 2.68 NaOH 61.88 4.55 35.81 1.37 97.69 3.30 (*) 10 minutes conditioning retention time _____________________ B/S: Bitumen-to-Solids mass ratio Table 1 ¨ Bitumen extraction tests with high-grade ore EC Alkalinity (mg-CaCO3/L) Cations (mOL) Anions (mg/L) Additive pH (mS/cm) Total CO3- HCO3- Na" Mg2+ Ca2+ Cl- S042-PW 8.7 1.80 288 14 274 340 13 17 179 CaO 8.4 1.77 229 2 227 334 10 17 187 CaO(*) 8.5 1.76 241 8 233 338 11 20 185 NaOH 8.8 1.90 298 26 272 384 _ 5 6 184 247 (*) 10 minutes conditioning retention time B/S: Bitumen-to-Solids mass ratio Table 2¨ Water chemistry, bitumen extraction tests with high-grade ore
- 9 -Date Recue/Date Received 2020-12-14 Primary bitumen extraction efficiency with CaO additive increased from about 46% to 65% by allowing 10 minutes ore-water conditioning time with a very mild agitation, while the B/S ratio remained at about 3.7. These results indicate that bitumen was liberated to a greater extent by allowing a longer ore-water slurry conditioning retention time. Total bitumen recoveries were obtained using NaOH and CaO
additives were about 97.7% and 95.0% respectively.
Also using high-grade oil sands ore, bitumen extraction tests were performed with both NaOH and CaO as additives, with air intake in the primary extraction step; the corresponding bitumen extraction and process water chemistry results are presented in Table 3 and Table 4 respectively (below):
Primary Froth Secondary Froth Total Bitumen Bitumen Bitumen Recovery B/S Recovery B/S Recovery B/S
Additive (%) Ratio (%) Ratio (%) Ratio CaO 62.12 3.70 35.25 1.75 97.37 2.92 NaOH 71.04 2.78 24.46 2.94 95.50 2.69 B/S: Bitumen-to-Solids mass ratio Table 3¨ Bitumen extraction tests with high-grade ore, primary recovery with air intake EC Alkalinity (mg-Ca CO3/L) Cations (mg/L) Anions (mg/L) Additive pH (mS/cm) Total CO3- HCO3- Na" Mg2+ Ca2+ Cl- S042-PW 8.7 1.80 288 14 274 340 13 17 CaO 8.4 1.77 243 4 239 331 11 19 NaOH 8.8 1.91 313 24 289 390 6 8 Table 4¨ Water chemistry, bitumen extraction tests with high-grade ore, primary recovery with air intake With air intake in the primary extraction step and short conditioning times, both NaOH and CaO additives provided higher bitumen recovery efficiency. However, because of limited ore-water slurry conditioning, bitumen froths were of lower B/S ratios.
additives were about 97.7% and 95.0% respectively.
Also using high-grade oil sands ore, bitumen extraction tests were performed with both NaOH and CaO as additives, with air intake in the primary extraction step; the corresponding bitumen extraction and process water chemistry results are presented in Table 3 and Table 4 respectively (below):
Primary Froth Secondary Froth Total Bitumen Bitumen Bitumen Recovery B/S Recovery B/S Recovery B/S
Additive (%) Ratio (%) Ratio (%) Ratio CaO 62.12 3.70 35.25 1.75 97.37 2.92 NaOH 71.04 2.78 24.46 2.94 95.50 2.69 B/S: Bitumen-to-Solids mass ratio Table 3¨ Bitumen extraction tests with high-grade ore, primary recovery with air intake EC Alkalinity (mg-Ca CO3/L) Cations (mg/L) Anions (mg/L) Additive pH (mS/cm) Total CO3- HCO3- Na" Mg2+ Ca2+ Cl- S042-PW 8.7 1.80 288 14 274 340 13 17 CaO 8.4 1.77 243 4 239 331 11 19 NaOH 8.8 1.91 313 24 289 390 6 8 Table 4¨ Water chemistry, bitumen extraction tests with high-grade ore, primary recovery with air intake With air intake in the primary extraction step and short conditioning times, both NaOH and CaO additives provided higher bitumen recovery efficiency. However, because of limited ore-water slurry conditioning, bitumen froths were of lower B/S ratios.
- 10 -Date Recue/Date Received 2020-12-14 In these tests, total bitumen recovery with NaOH and CaO additives were about 96% and 97% respectively, while total B/S ratios were about 2.7 and 2.9 respectively.
The long-term effects of extraction process additives on extraction process efficiency were tested by performing two consecutive tests, by recycling the release water recovered form the first test and using it as process water for the second extraction test, without importing fresh water from external sources; these tests are called Two Lock Cycle tests. Bitumen extraction data obtained using NaOH and CaO additives, with corresponding process water chemistry data, are presented in Table 5 and Table respectively (below):
Primary Froth Secondary Froth Total Recovery B/S Recovery B/S Recovery B/S
Additive Cycle (%) Ratio (%) Ratio (%) Ratio NaOH 1 84.6 4.76 7.3 1.22 91.9 4.12 NaOH 2 80.2 4.00 7.5 1.19 87.7 3.30 CaO 1 89.7 3.57 6.2 1.14 95.9 3.27 CaO 2 89.3 4.00 6.1 1.14 95.4 3.64 B/S: Bitumen-to-Solids mass ratio _____________________________ Table 5- Bitumen extraction tests, normal-grade ore, using NaOH and CaO
additives without importing fresh water Alkalinity Cations Anions EC (mg-CaCO3/l) (mg/l) (mg/l) Additive Cycle pH (mS/cm) Total HCO3- Na+ Ca2+ Mg2+ Cl- SO4=
APW APW 8.6 1420 394 450 299 13.3 8.5 NaOH 1 8.7 1570 480 539 334 3.1 4.4 175 NaOH 2 8.8 1690 488 537 366 1.9 3.7 183 CaO 1 8.7 1480 371 414 305 4.7 3.7 185 CaO 2 8.7 1480 350 393 311 3.2 2.4 187 Table 6- Water chemistry, normal-grade ore bitumen extraction tests, normal grade ore, using NaOH and CaO additives without importing fresh water In these tests, CaO addition provided higher total bitumen extraction efficiencies of about 95.9% and 95.4% for the first and second Lock Cycles, while the total bitumen
The long-term effects of extraction process additives on extraction process efficiency were tested by performing two consecutive tests, by recycling the release water recovered form the first test and using it as process water for the second extraction test, without importing fresh water from external sources; these tests are called Two Lock Cycle tests. Bitumen extraction data obtained using NaOH and CaO additives, with corresponding process water chemistry data, are presented in Table 5 and Table respectively (below):
Primary Froth Secondary Froth Total Recovery B/S Recovery B/S Recovery B/S
Additive Cycle (%) Ratio (%) Ratio (%) Ratio NaOH 1 84.6 4.76 7.3 1.22 91.9 4.12 NaOH 2 80.2 4.00 7.5 1.19 87.7 3.30 CaO 1 89.7 3.57 6.2 1.14 95.9 3.27 CaO 2 89.3 4.00 6.1 1.14 95.4 3.64 B/S: Bitumen-to-Solids mass ratio _____________________________ Table 5- Bitumen extraction tests, normal-grade ore, using NaOH and CaO
additives without importing fresh water Alkalinity Cations Anions EC (mg-CaCO3/l) (mg/l) (mg/l) Additive Cycle pH (mS/cm) Total HCO3- Na+ Ca2+ Mg2+ Cl- SO4=
APW APW 8.6 1420 394 450 299 13.3 8.5 NaOH 1 8.7 1570 480 539 334 3.1 4.4 175 NaOH 2 8.8 1690 488 537 366 1.9 3.7 183 CaO 1 8.7 1480 371 414 305 4.7 3.7 185 CaO 2 8.7 1480 350 393 311 3.2 2.4 187 Table 6- Water chemistry, normal-grade ore bitumen extraction tests, normal grade ore, using NaOH and CaO additives without importing fresh water In these tests, CaO addition provided higher total bitumen extraction efficiencies of about 95.9% and 95.4% for the first and second Lock Cycles, while the total bitumen
- 11 -Date Recue/Date Received 2020-12-14 extraction efficiencies withNaOH addition were about 91.9% and 87.7% for the first and second Lock Cycles.
Process water chemistry data presented in Table 2, Table 4, and Table 6 show that the use of CaO does not harm process water chemistry, while NaOH addition increases the salinity and sodium ion concentration of the process water.
Because of variances in the composition and properties of oil sands ore and water used as process water in bitumen extraction processes, optimal retention times for the ore conditioning (or first) stage and the bitumen-rich froth formation (or second) stage of commercial implementations of methods in accordance with the present disclosure may vary, and the selection of appropriate retention times for these process stages will be refined with the generation of additional data from operating facilities.
It will be readily appreciated by those skilled in the art that various modifications to embodiments in accordance with the present disclosure may be devised without departing from the present teachings, including modifications which may use structures or materials later conceived or developed. It is to be especially understood that the scope of the present disclosure should not be limited by or to any particular embodiments described, illustrated, and/or claimed herein, but should be given the broadest interpretation consistent with the disclosure as a whole. It is also to be understood that the substitution of a variant of a claimed element or feature, without any substantial resultant change in functionality, will not constitute a departure from the scope of the disclosure or claims.
In this patent document, any form of the word "comprise" is intended to be understood in a non-limiting sense, meaning that any element or feature following such word is included, but elements or features not specifically mentioned are not excluded. A
reference to an element or feature by the indefinite article "a" does not exclude the possibility that more than one such element or feature is present, unless the context clearly requires that there be one and only one such element. Wherever used herein, any form of the word "typical" is to be understood in the sense of representative or common usage or practice, and not as implying invariability or essentiality.
Process water chemistry data presented in Table 2, Table 4, and Table 6 show that the use of CaO does not harm process water chemistry, while NaOH addition increases the salinity and sodium ion concentration of the process water.
Because of variances in the composition and properties of oil sands ore and water used as process water in bitumen extraction processes, optimal retention times for the ore conditioning (or first) stage and the bitumen-rich froth formation (or second) stage of commercial implementations of methods in accordance with the present disclosure may vary, and the selection of appropriate retention times for these process stages will be refined with the generation of additional data from operating facilities.
It will be readily appreciated by those skilled in the art that various modifications to embodiments in accordance with the present disclosure may be devised without departing from the present teachings, including modifications which may use structures or materials later conceived or developed. It is to be especially understood that the scope of the present disclosure should not be limited by or to any particular embodiments described, illustrated, and/or claimed herein, but should be given the broadest interpretation consistent with the disclosure as a whole. It is also to be understood that the substitution of a variant of a claimed element or feature, without any substantial resultant change in functionality, will not constitute a departure from the scope of the disclosure or claims.
In this patent document, any form of the word "comprise" is intended to be understood in a non-limiting sense, meaning that any element or feature following such word is included, but elements or features not specifically mentioned are not excluded. A
reference to an element or feature by the indefinite article "a" does not exclude the possibility that more than one such element or feature is present, unless the context clearly requires that there be one and only one such element. Wherever used herein, any form of the word "typical" is to be understood in the sense of representative or common usage or practice, and not as implying invariability or essentiality.
- 12 -Date Recue/Date Received 2020-12-14
Claims (9)
CLAIMED ARE DEFINED AS FOLLOWS:
1. A method of processing oil sands ore comprising treatment of an oil sands ore-water slurry with calcium oxide (Ca0) at a dosage in the range of about 250 to 400 parts Ca0 per million parts oil sands ore by mass (ppm) ore mass, at a slurry temperature of about 50 to 60 degrees Celsius.
2. A method as in Claim 1 wherein the Ca0 is provided in the form of quick lime and/or hydrated lime.
3. A method as in Claim 1 or Claim 2 wherein the ore-water slurry is prepared by blending approximately equal masses of oil sands ore and process water.
4. A method as in any one of Claims 1-3 wherein the oil sands ore-water slurry is conditioned by gentle agitation or stirring to liberate bitumen from the oil sands ore matrix and to separate substantially bitumen-free sand grains from the ore-water slurry.
5. A method as in any one of Claims 1-5, comprising the further step of injecting air into the ore-water slurry to produce a bitumen-rich froth.
6. A method as in Claim 5 wherein the bitumen-rich froth contains at least 50%
bitumen by weight, and nor more than 15% solids by weight.
bitumen by weight, and nor more than 15% solids by weight.
7. A method as in Claim 5 or Claim 6, comprising the further step of transporting the bitumen-rich froth to an oil sands plant by pipeline.
8. A method as in any one of Claims 5-7 wherein tailings effluents produced by the ore-conditioning and froth-production processes are combined and disposed as non-segregating tailings.
9. A method as in Claim 8 wherein the tailings effluents are treated with Ca0.
Date Recue/Date Received 2020-12-14
Date Recue/Date Received 2020-12-14
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