CA2581992A1 - Gravity powered and cleaning flotation circuits - Google Patents
Gravity powered and cleaning flotation circuits Download PDFInfo
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- CA2581992A1 CA2581992A1 CA 2581992 CA2581992A CA2581992A1 CA 2581992 A1 CA2581992 A1 CA 2581992A1 CA 2581992 CA2581992 CA 2581992 CA 2581992 A CA2581992 A CA 2581992A CA 2581992 A1 CA2581992 A1 CA 2581992A1
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- flotation
- froth
- feeding
- middlings
- bitumen
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- 238000005188 flotation Methods 0.000 title claims abstract description 194
- 238000004140 cleaning Methods 0.000 title claims abstract description 51
- 230000005484 gravity Effects 0.000 title claims abstract description 14
- 239000010426 asphalt Substances 0.000 claims abstract description 98
- 238000000926 separation method Methods 0.000 claims abstract description 56
- 238000000034 method Methods 0.000 claims abstract description 44
- 230000008569 process Effects 0.000 claims abstract description 43
- 239000002002 slurry Substances 0.000 claims abstract description 41
- 239000004576 sand Substances 0.000 claims abstract description 30
- 239000004927 clay Substances 0.000 claims abstract description 24
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 22
- 239000002358 oil sand bitumen Substances 0.000 claims abstract description 18
- 238000011084 recovery Methods 0.000 description 11
- 238000005381 potential energy Methods 0.000 description 9
- 238000005273 aeration Methods 0.000 description 7
- 239000002245 particle Substances 0.000 description 6
- 238000000605 extraction Methods 0.000 description 5
- 239000003027 oil sand Substances 0.000 description 5
- 238000013019 agitation Methods 0.000 description 3
- 230000008901 benefit Effects 0.000 description 2
- 230000002706 hydrostatic effect Effects 0.000 description 2
- 229910052500 inorganic mineral Inorganic materials 0.000 description 2
- 238000012423 maintenance Methods 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 239000011707 mineral Substances 0.000 description 2
- 238000002360 preparation method Methods 0.000 description 2
- 230000004044 response Effects 0.000 description 2
- 239000002562 thickening agent Substances 0.000 description 2
- 238000011144 upstream manufacturing Methods 0.000 description 2
- 238000013459 approach Methods 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 239000003638 chemical reducing agent Substances 0.000 description 1
- 230000001010 compromised effect Effects 0.000 description 1
- 239000006185 dispersion Substances 0.000 description 1
- 230000005611 electricity Effects 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 238000009291 froth flotation Methods 0.000 description 1
- 125000000524 functional group Chemical group 0.000 description 1
- 230000008570 general process Effects 0.000 description 1
- 230000002209 hydrophobic effect Effects 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 238000010348 incorporation Methods 0.000 description 1
- 230000014759 maintenance of location Effects 0.000 description 1
- 230000007246 mechanism Effects 0.000 description 1
- 238000002156 mixing Methods 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 238000012545 processing Methods 0.000 description 1
- 238000000746 purification Methods 0.000 description 1
- 238000010992 reflux Methods 0.000 description 1
- 230000000630 rising effect Effects 0.000 description 1
- 238000012216 screening Methods 0.000 description 1
- 238000009987 spinning Methods 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 238000012546 transfer Methods 0.000 description 1
- 238000003260 vortexing Methods 0.000 description 1
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B03—SEPARATION OF SOLID MATERIALS USING LIQUIDS OR USING PNEUMATIC TABLES OR JIGS; MAGNETIC OR ELECTROSTATIC SEPARATION OF SOLID MATERIALS FROM SOLID MATERIALS OR FLUIDS; SEPARATION BY HIGH-VOLTAGE ELECTRIC FIELDS
- B03B—SEPARATING SOLID MATERIALS USING LIQUIDS OR USING PNEUMATIC TABLES OR JIGS
- B03B9/00—General arrangement of separating plant, e.g. flow sheets
- B03B9/02—General arrangement of separating plant, e.g. flow sheets specially adapted for oil-sand, oil-chalk, oil-shales, ozokerite, bitumen, or the like
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B03—SEPARATION OF SOLID MATERIALS USING LIQUIDS OR USING PNEUMATIC TABLES OR JIGS; MAGNETIC OR ELECTROSTATIC SEPARATION OF SOLID MATERIALS FROM SOLID MATERIALS OR FLUIDS; SEPARATION BY HIGH-VOLTAGE ELECTRIC FIELDS
- B03D—FLOTATION; DIFFERENTIAL SEDIMENTATION
- B03D1/00—Flotation
- B03D1/02—Froth-flotation processes
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- Life Sciences & Earth Sciences (AREA)
- Chemical & Material Sciences (AREA)
- Geology (AREA)
- Oil, Petroleum & Natural Gas (AREA)
- Physical Water Treatments (AREA)
Abstract
An oil sand bitumen flotation process and apparatus involving (i) feeding an aerated slurry comprising bitumen, sand, clay and water to a primary separation cell to produce a middlings stream, (ii) feeding the middlings stream to roughing middlings unit to produce a roughing middlings froth; (iii) feeding the roughing middlings froth to a cleaning unit to produce upgraded bitumen froth and collecting the upgraded bitumen froth. The invention also includes an oil sand bitumen flotation process including (i) feeding an aerated slurry comprising bitumen, sand, clay and water to a primary separation cell to produce a middlings stream; (ii) feeding the middlings stream to flotation means to produce a middlings froth and middlings tailings, characterized in feeding the middlings stream under gravity flow to the flotation means.
Description
GRAVITY POWERED AND CLEANING FLOTATION CIRCUITS
FIELD OF THE INVENTION
This invention relates to gravity powered flotation and cleaning circuits of use in the cleaning of mineral slurries, particularly within commercial oil sand bitumen flotation circuits.
BACKGROUND OF THE INVENTION
Traditionally, oil sand is mined from large surface-accessible deposits and, subsequently, undergoes a series of screening, crushing of oversize material and tumbling steps to break apart frozen and/or consolidated lumps. Hot water is added and, depending on the operation, some chemicals to facilitate clay dispersion are also metered in, with the aerated slurry then being transported several kilometres via a pipeline to the extraction plant.
There are variations on this general process with several new operations considering using either counter-current drum separators or hydrocyclones to reject coarse sand close to the mine.
The extraction plant units and process steps flow sheet also varies, depending on the mine. Existing operations utilize a primary separation stage using a primary separation cell (PSC) where this very large vessel separates aerated bitumen from coarse sand, clay, and water through a combination of flotation of the aerated bitumen and settling of the sand and clays. The PSC also has a mid-vessel take-off line that is used for level control and middlings recovery. Middlings are aggregates of bitumen, sand, and water that neither tends to float or sink but to reflux in and near the interface between the bitumen froth and the slurry zone.
This mid-level middlings take-off stream provides for traditional flotation to occur involving multiple stages of flotation cells arranged in series. All flotation cells mentioned herein are continuous devices, i.e. they operate on a continuous basis, wherein slurry feed enters the cell, froth is removed from the surface and tailings exit from a valve or weir assembly. In the lexicon of the mineral processing industry these flotation cells would be the equivalent of a rough flotation step or a "roughing" step. In all existing Canadian oil sand operations, the froth from the flotation cells is recycled back to the feed and then to the PSC, as it is too low a grade to be sent to the next purification step - being froth treatment.
Flotation cell froth is not only lower in grade but it also is the most stubborn component of the fresh feed bitumen, perhaps, because of oil-wet clays, emulsified water, or the presence of functional groups on the surface of the bitumen that makes it more hydrophilic than clean bitumen. Returning this slow-floating and difficult-to-separate material to the feed and to the PSC, means that the PSC must float two very different bitumen streams. One stream is the fresh feed with relatively fast-floating and clean separating bitumen, while the other is the middlings recycle, with its stubborn slow-floating bitumen aggregates. The PSC must, as a consequence, be operated as a compromise to both of these feed components. It cannot be pulled, i.e. operated in a manner that results in a high mass recovery to the froth, as hard as it could if only fresh feed was present.
Rather, it must be operated more slowly so that only the grade-acceptable portion of the middlings stream reports to the froth, lest all of the middlings is recovered and the overall grade of the PSC
froth drops below froth treatment feed quality standards. This common configuration, therefore, results in lower PSC bitumen recovery because it cannot be pulled as hard as it could if the middlings froth was not recycled.
All flotation cells require energy in some form to work. To date, the most common flotation device used in the Canadian oil sands is the mechanical cell that employs a rotating mixer (rotor) and a stationary assembly (stator) to prevent vortexing within the flotation cell.
Air is passed into the cell to provide a mechanism for the hydrophobic bitumen to attach and rise to the surface, where the froth is collected in troughs or launders. The mixing energy imparted by the rotor brings gas bubbles in contact with bitumen so the bitumen droplets or particles can be collected and separated from the sand and water. Electrical energy converted to mechanical energy by the motor, sheaves, gear reducers, and rotor is necessary to mix the slurry and collect the bitumen on the gas bubbles so the bitumen can be separated and recovered out of the slurry.
Other flotation devices that are of potential for use in the oil sands also require energy to work. Feed-slurry-aeration cells, i.e. external gas contacting flotation cells employ the pressure drop across a slurry flow restriction to impart shear energy to the slurry-gas mixture and, thus, provide the energy needed for bitumen to overcome bubble surface tension and laminar flow and collect on the bubble. Colunm cells use less energy within the cell, but require the slurry to be pumped many metres vertically so the counter-current flow of rising gas bubbles versus the settling sand and bitumen can be established for the required stage retention time. This energy, whether it is in the form of a motor-rotor assembly or pumps, is an operating cost penalty for the operations in the form of consumed electricity, consequent environmental emissions, and wear on equipment that will require regular maintenance.
There is, therefore, a need to improve the aforesaid compromised prior art processes, which improvement would result in an operation that results in a higher mass recovery to the froth and enhanced floating rate of the bitumen aggregates of the middlings recycle.
Oil sand extraction plant processes that employ a PSC must pump bitumen slurry into the PSC and which, thus, is many metres in height. A typical PSC would be 20 to 30 metres in diameter and over 30 metres tall. The slurry within the PSC, therefore, represents considerable potential energy that can be used for slurry transport and, innovatively, to power a flotation machine. It is an object of the present invention to exploit the potential energy contained within a PSC or any other step in an oil sands flowsheet where bitumen slurry is high relative to either grade or sub-grade structures for the purposes of powering a flotation device.
SUMMARY OF THE INVENTION
The present invention in one aspect provides for a solution to the recovery and grade problem created by the aforesaid prior art compromise by upgrading the middlings flotation froth separately from the PSC to an acceptable grade and then send it directly to froth treatment. To do this, the roughing middlings froth is floated again in a cleaning stage. This is not used anywhere in the Canadian oil sands. The invention utilizes the use of one or more cleaning stages for the purposes of increasing the bitumen content of the final froth stream.
A cleaning stage is defmed as the re-floating of froth from a middlings or a PSC tailings flotation circuit or from a previous cleaning stage. It is, therefore, the second, third, etc.
flotation step of a bitumen froth with the goal of upgrading that stream in terms of its bitumen content or grade.
Accordingly, in one aspect, the invention provides an oil sand bitumen flotation process comprising (i) feeding an aerated slurry comprising bitumen, sand, clay and water to a primary separation cell to produce a middlings stream, (ii) feeding said middlings stream to roughing middlings means to produce a roughing middlings froth;
(iii) feeding said roughing middlings froth to cleaning means to produce upgraded bitumen froth and collecting said upgraded bitumen froth.
Preferably, the process fiuther comprises feeding the upgraded bitumen froth to froth treatment means.
In a further aspect, the invention provides an oil sand bitumen flotation process comprising (i) feeding an aerated slurry comprising bitumen, sand, clay and water to a primary separation cell;
(ii) removing aerated bitumen from said primary separation cell;
(iii) removing said sand and clay as tailings from said primary separation cell;
(iv) removing a middlings stream from said primary separation cell;
(v) feeding said middlings stream to flotation means;
(vi) removing a first middlings froth from said flotation means;
(vii) removing tailings from said flotation means;
characterized in feeding said first middlings froth of step (vi) to first flotation cleaning means to produce an upgraded bitumen stream.
The process, as hereinabove defined, preferably has the flotation means selected from flotation column means and flotation contact cell means.
In one aspect, the invention provides a process wherein the flotation means is a flotation column means and further comprises feeding the tailings of step (vii) constituting flotation column tailings to first contract cell means in series with the flotation column, to produce a first contact cell froth and feeding the first contact cell froth to second flotation cleaning means to produce an upgraded bitumen stream.
In a further aspect, the invention provides a process further comprising feeding the sand and clay tailings of step (iii) to hydrocyclone means to produce a cyclone overflow and feeding the overflow to second contact cell means to produce a second contact cell froth, and feeding the second contact cell froth to third floatation cleaning means to produce an upgraded bitumen stream.
In a further aspect, the invention provides a process as hereinabove defmed further comprising removing primary separation cell froth from the primary separation cell and feeding said primary separation cell froth to fourth flotation cleaning means to produce an upgraded bitumen stream.
In preferred embodiments, the invention as hereinabove defmed provides a process wherein the first, second, third and fourth flotation cleaning means are the same.
In further embodiments, the invention provides a process wherein the upgraded bitumen stream is fed to froth treatment means to produce upgraded bitumen.
By the term "upgraded bitumen stream" is mean enhancement of the bitumen grade, either by % by weight or volume of the stream relative to the input froth grade.
In this specification and claims the term "contact cells" means one or more, used in series or parallel, of the feed-slurry-aeration family of froth flotation devices.
The flotation cleaning means may comprise one or more flotation cleaning units, which is defined herein as a unit that re-floats froth from a previous flotation stage, which stage can be mechanical, column, feed-slurry-aeration, or a primary separation device.
Cleaning the froth from a middlings or PSC tailings stream means that the quality, i.e.
bitumen, water, mineral content, can be improved so the stream can be sent to froth treatment and not recycled back to the PSC. This means that the PSC can be pulled harder, solely in response to the fresh feed, and not held back for fear of recovering excessive amounts of low-grade middlings to the froth, which would reduce grade and create downstream problems.
Pulling the PSC harder, and pulling the middlings and PSC tailings flotation circuits according to the dynamics of their systems, will result in higher overall bitumen recoveries.
It will be readily appreciated that bitumen recovery, at acceptable grade, is the goal of the extraction plant.
In a further aspect, the invention provides an oil sand bitumen flotation circuit apparatus comprising (i) a primary separation cell, (ii) means for feeding an aerated slurry comprising bitumen, sand, clay and water to said primary separation cell to produce a middlings stream, (iii) roughing middlings means, (iv) means for feeding said middlings stream to said roughing middlings means to produce a roughing middlings froth;
(v) cleaning means, (vi) means for feeding said roughing middlings froth to said cleaning means to produce upgraded bitumen froth; and (vii) means for collecting said upgraded bitumen froth.
In a further aspect, the invention provides an apparatus further comprising (viii) froth treatment means; and (ix) means for feeding said upgraded bitumen froth to said froth treatment means.
In a further aspect, the invention provides an oil sand bitumen flotation circuit apparatus comprising (i) a primary separation cell, (ii) means for feeding an aerated slurry comprising bitumen, sand, clay and water to a primary separation cell;
(iii) means for removing aerated bitumen from said primary separation cell;
(iv) means for removing said sand and clay as tailings from said primary separation cell;
(v) means for removing a middlings stream from said primary separation cell;
(vi) flotation means;
(vii) means for feeding said middlings stream to said flotation means;
(viii) means for removing a first middlings froth from said flotation means;
(ix) means for removing tailings from said flotation means;
characterized in having (x) a first flotation cleaning means; and (xi) means for feeding said first middlings froth of step (vi) to said first flotation cleaning means to produce an upgraded bitumen stream.
In preferred embodiments the flotation means is selected from flotation column means and flotation contact cell means.
In further embodiments, the invention provides an apparatus wherein said flotation means is flotation column means and further comprising (xii) first contact cell means, (xiii) second contact cell means; and (xiv) means for feeding said tailings of step (vii) constituting flotation column tailings to said first contract cell means in series with said flotation column means, to produce a first contact cell froth and feeding said first contact cell froth to said second flotation cleaning means to produce an upgraded bitumen stream.
In a further aspect, the invention provides an apparatus as hereinabove defmed further comprising (xv) hydrocyclone means, (xvi) third flotation cleaning means and (xvii) means for feeding said sand and clay tailings of step (iii) to said hydrocyclone means to produce a cyclone overflow, and feeding said overflow to said second contact cell means to produce a second contact cell froth, and feeding said second contact cell froth to said third floatation cleaning means to produce an upgraded bitumen stream.
In a further aspect, the invention provides an apparatus as hereinabove defmed further comprising (xviii) fourth flotation cleaning means and (xiv) means for removing primary separation cell froth from said primary separation cell and feeding said primary separation cell froth to said fourth flotation cleaning means to produce an upgraded bitumen stream.
In a further aspect, the invention provides an apparatus as hereinabove defined wherein two or more of said first, second, third and fourth flotation cleaning means are the same.
In a further aspect, the invention provides an apparatus as hereinabove defmed further comprising (xx) froth treatment means and (xxi) means for feeding said upgraded bitumen stream to said froth treatment means to produce upgraded bitumen.
In a further aspect, the invention provides an oil sand bitumen flotation process comprising (i) feeding an aerated slurry comprising bitumen, sand, clay and water to a primary separation cell to produce a middlings stream;
(ii) feeding said middlings stream to flotation means to produce a middlings froth and middlings tailings, characterized in feeding said middlings stream under gravity flow to said flotation means.
In a further aspect, the invention provides a process as hereinabove defined wherein the flotation means is selected from flotation column means and flotation contact cell means.
In a further aspect, the invention provides a process as hereinabove defined wherein the flotation means is flotation column means and which process produces a flotation column froth and flotation column tailings.
In a further aspect, the invention provides a process as hereinabove defmed wherein the flotation means is flotation contact cell means.
In yet a further aspect, the invention provides a process as hereinabove defmed further comprising feeding the flotation column tailings to flotation contact cell means to produce a flotation contact cell froth and contact cell tailings.
In a further aspect, the invention provides an oil sand bitumen flotation circuit comprising (i) a primary separation cell;
(ii) feeding an aerated slurry comprising bitumen, sand, clay and water to said primary separation cell to produce a middlings stream;
(iii) flotation means;
(iv) means for feeding said middlings stream to said flotation means to produce a middlings froth and middlings tailings, characterized in (v) means for feeding said middlings stream under gravity flow to said flotation means.
In a further aspect, the invention provides an apparatus as hereinabove defmed wherein the flotation means is selected from flotation column means and flotation contact cell means.
In a further aspect, the invention provides an apparatus as hereinabove defmed wherein the flotation means is flotation column means.
In a further aspect, the invention provides an,apparatus as hereinabove defmed wherein the flotation means is flotation contact cell means.
BRIEF DESCRIPTION OF THE DRAWINGS
In order that the invention may be better understood, preferred embodiments will now be described, by way of example only, wherein Figs. 1 and 2 are diagrammatic representations of oil sand bitumen flotation processes and apparatus according to the prior art;
Figs. 3 and 4 are diagrammatic representations of oil sand bitumen flotation processes and apparatus according to the invention, and wherein the same numerals denote like parts.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
With reference to Fig. 1, this shows generally as 10, a prior art bubble-particle collection circuit, showing the sources of energy necessary for froth collection, having a pair of primary separation cells 12 to which is fed fresh feed 14 and from which is obtained bitumen froth 16, non-segregating tailings 18 and 1 middlings take-off stream 20.
In this embodiment, the collection energy comes from mechanical agitation imported to the slurry within the plurality of mechanical cells 22 each having a spinning rotor (not shown). This step requires consumption of electrical energy, but does not utilize the potential energy held by the slurry in the upstream process when it is present in the primary separation cells 12, in the formation of the bitumen/gas bubble froth in mechanical cells 22. Further, pumps 24 are required to feed middlings stream 20 and non-segregated tailings froth stream 26.
Fig. 2 shows, generally as 100, an alternative prior art bubble-particle collection circuit apparatus and process requiring input energy, but not using the potential energy stored in the slurry present in the upstream primary separation cells 12. In this embodiment, mechanical cells 22 have been replaced by column cells 28 requiring column feed pumps 30, which provide electrical/mechanical energy to get the slurry and gas bubbles can manifest and create the conditions for bubble-particle froth collection.
An embodiment of a cleaning flotation circuit according to the invention can be seen in Fig. 3 wherein there are three roughing flotation stages represented. The primary separation cell receives fresh feed from the hydrotransport system or some other feed preparation step. A middlings stream is used for level control of the PSC and to send a dilute slurry stream to the flotation circuit where additional bitumen is recovered.
The first flotation step is a flotation column and the tailings of the column flow to the next flotation stage, being a contact cell. The tailings from the PSC are pumped to a hydrocyclone stage with the cyclone overflow being treated in another flotation a contact cell.
As mentioned, hereinbefore, current practice in the Canadian oil sands is to recycle the froth from the roughing stages back to the PSC. In this embodiment, however, the froth from all three roughing stages reports to a cleaning stage where the bitumen content is upgraded enough so it can be sent directly to the froth treatment process. If one stage of cleaning is not enough then multiple stages can be used. There are a variety of options for handling the tailings from the cleaning steps.
In more detail, Fig. 3, shows generally as 200, an oil sand bitumen flotation cleaning circuit apparatus and process according to the invention.
Circuit 200 has primary separation cell 12 to which is fed fresh feed 14 and from which bitumen froth 16, non-segregating tailings 18 and middlings tailings 20 are run off.
Middlings stream 20 is fed to a first flotation stage feed slurry aeration column cell 32. Froth 31 from stage 32 is fed to a combined flotation stage cell 33.
Tailings from stage 32 are passed to a second flotation stage contact cell 34 to provide froth 35 which is combined with froth 31 and passed also to combined flotation stage cell 33.
Tailings from cell 34 exit circuit 200.
PSC 12 tailings are pumped to hydrocyclone 36 wherein non-segregating tailings exit circuit 200. Hydrocyclone overflow process stream 39 from hydrocyclone 36 is fed to a third flotation stage cell 38 to produce non-segregated tailings stream 41 which exits circuit 200 and froth 42, which is combined with froth streams 31 and 35 for transfer to combined flotation stage cell 33. Tailings from cell 33 are recycled through contact 44 to PSC
middlings stream 20 while cell 33 froth 46 is fed to treatment unit 46.
Bitumen froth 46 is of a sufficient quality to report to froth treatment and not be recycled to the PSC.
It should be noted that the incorporation of cleaning stage 33 provides the most preferred embodiment of the present invention.
In the aspect of the present invention directed to use of gravity powered flotation as hereinbefore defined, and described hereinbelow, the primary separation cell receives fresh feed from the hydrotransport system or some other feed preparation step. A
middlings stream is used for level control of the PSC and to send a dilute slurry stream to the flotation circuit where additional bitumen is recovered. The first flotation step is a flotation column and the tailings of the column flow to the next flotation stage, being a contact cell.
The tailings from the PSC are pumped to a hydrocyclone stage with the cyclone overflow being treated in another contact cell flotation cell. The two flotation stages on the PSC
middlings stream exploit the potential energy of the PSC slurry. The column requires no pump and, hence, no energy to get the slurry into the cell so the counter-current flow within the column can be established. Similarly, the contact cell stage after the column utilizes the potential energy, i.e.
hydrostatic head within the column to create a pressure drop across a feed restriction so the shear field necessary for bitumen collection can be established. No pump is required.
In more detail, Fig. 4 shows generally as 300 a gravity powered flotation circuit apparatus and process according to the invention having a pair of primary separation cells 12 fed with fresh food 14 and which provides between froth 16, PSC tailings 18 and middlings stream 20.
Circuit 300 has a feed slurry aeration cell 50 as a first flotation stage, and a contact cell 52 as a second flotation stage. Hydrocyclones 54 are used to treat tailings 18 to provide hydrocyclones overflowers 56. Cells 50 produces first flotation stage tailings 58 which are fed to contact cells 52, whereby second flotation tailings 60 are passed as combined flotation tailings 62 to thickener 64, which produces non-segregating tailings built from the coarse sand obtained from the hydrocyclone underflow and thickener underflow.
Hydrocyclone flow 56 is treated in flotation stage 68 to provide tailings 70 and froth 72 which is fed back to PSC 12, while hydrocyclone underflow of coarse sand and a little water exit circuit 300.
First and second stage froths 72 and 74, respectively, are combined and recycled with primary feed 14 to PSC 12.
The elevation of the hydrocyclones 54 treating PSC tails 18 provides enough hydrostatic head, i.e. potential energy to drive contactor 68 of the third flotation stage. The contractor is that part of a contact flotation cell wherein gas bubbles and slurry are in intimate contact before, through, and after a shear field generated by a pressure drop across a restriction in the feed pipe.
The columns and Contact Cells flotation machines used in this embodiment uses no pumps, rotors, electric motors, or dedicated energy of any kind for the collection of bitumen and its separation, via the froth interface. The energy needed for these cells to work, defined as the energy needed for the bubble-particle collection process to occur in a reasonable amount of time, is provided exclusively by potential energy stored in the slurry as a result of transporting the slurry to either the PSC 12 or to hydrocyclones 54. These are true gravity powered flotation devices and circuits. Flotation columns or any of the family of feed-slurry-aeration devices, also known as external gas contacting flotation devices on the market, can be used within a gravity powered circuit similar to that as described herein.
The essence of the present invention is the exploitation of gravity in the form of slurry potential energy, as a result of other processes, such as primary separation in a PSC, to enable the bubble-particle, or droplet collection process, in one or more flotation stages. The invention includes flotation circuits wherein the aeration of the slurry requires an external energy source and it, also, includes circuits that are self-aspirating, i.e.
having no blowers or compressors.
The invention provides in one aspect the benefits of lower energy and operating costs for the oil sand producers. _ Table 1 shows an example of the energy savings of a gravity powered over a conventional mechanical cell circuit for a new oil sand project. Savings in power alone approach $1 million per year. Added to this sum would be capital savings from fewer pumps or electric motors; maintenance on the pumps, rotors, or stators; and higher availability of the flotation circuit which is probably the biggest revenue argument of all.
Mechanical cells Contact Columns/cells Contact Contact Column (2) Cells (4) Cell volume 160 m3 Cell diameter 7.0 m 7.0 6.0 m Effective cell footprint (assume square) 49.0 m2 49.0 36.0 m2 $/kWh 0.05 Availability 95%
Total #ofcells 15 2 4 6 Footprint 735 mZ 98 .144 242 m2 Jg 1.3 cm/s 0.6 0.6 cm/s Air 27,016 m3/h 1,663 2,443 4,105 m3/h Agitation? Y No No kW_AIR 500 500 kW_AGITATION 1,950 N/A
kWh per year 20,388,900 4,161,000 Annual power cost $1,019,445 $208,050 Power savings $811,395 The present invention in a.further aspect provides the benefit that cleaning the froth from a middlings or PSC tailings stream means that the quality (bitumen, water, mineral content) can be improved so the stream can be sent to froth treatment and not recycled back to the PSC. This means that the PSC can be pulled harder, solely in response to the fresh feed, and not held back for fear of recovering excessive amounts of low grade middlings to the froth, which would reduce grade and create downstream problems. Pulling the PSC
harder, and pulling the middlings and PSC tailings flotation circuits according to the dynamics of their system, will result in higher overall bitumen recoveries.
Bitumen recovery, at acceptable grade, is the goal of the extraction plant.
Table 2 illustrates what a 1% increase in bitumen recovery would be worth at today's oil prices and for an operation producing 100,000 barrels per day of oil.
Additional barrels from higher recovery 1,000 Discount rate 9%
Price per barrel $60 Operating cost per barrel $20 Plant availability 95%
Year Income Expense Net NPV
1 $0 $0 2 $13,870,000 $0 $13,870,000 3 $13,870,000 $0 $13,870,000 4 $13,870,000 $0 $13,870,000 $13,870,000 $0 $13,870,000 $41,224,692 6 $13,870,000 $0 $13,870,000 7 $13,870,000 $0 $13,870,000 8 $13,870,000 $0 $13,870,000 9 $13,870,000 $0 $13,870,000 $13,870,000 $0 $13,870,000 $76,288,142 Although this disclosure has described and illustrated certain preferred embodiments of the invention, it is to be understood that the invention is not restricted to those particular 5 embodiments. Rather, the invention includes all embodiments, which are functional or mechanical equivalence of the specific embodiments and features that have been described and illustrated.
FIELD OF THE INVENTION
This invention relates to gravity powered flotation and cleaning circuits of use in the cleaning of mineral slurries, particularly within commercial oil sand bitumen flotation circuits.
BACKGROUND OF THE INVENTION
Traditionally, oil sand is mined from large surface-accessible deposits and, subsequently, undergoes a series of screening, crushing of oversize material and tumbling steps to break apart frozen and/or consolidated lumps. Hot water is added and, depending on the operation, some chemicals to facilitate clay dispersion are also metered in, with the aerated slurry then being transported several kilometres via a pipeline to the extraction plant.
There are variations on this general process with several new operations considering using either counter-current drum separators or hydrocyclones to reject coarse sand close to the mine.
The extraction plant units and process steps flow sheet also varies, depending on the mine. Existing operations utilize a primary separation stage using a primary separation cell (PSC) where this very large vessel separates aerated bitumen from coarse sand, clay, and water through a combination of flotation of the aerated bitumen and settling of the sand and clays. The PSC also has a mid-vessel take-off line that is used for level control and middlings recovery. Middlings are aggregates of bitumen, sand, and water that neither tends to float or sink but to reflux in and near the interface between the bitumen froth and the slurry zone.
This mid-level middlings take-off stream provides for traditional flotation to occur involving multiple stages of flotation cells arranged in series. All flotation cells mentioned herein are continuous devices, i.e. they operate on a continuous basis, wherein slurry feed enters the cell, froth is removed from the surface and tailings exit from a valve or weir assembly. In the lexicon of the mineral processing industry these flotation cells would be the equivalent of a rough flotation step or a "roughing" step. In all existing Canadian oil sand operations, the froth from the flotation cells is recycled back to the feed and then to the PSC, as it is too low a grade to be sent to the next purification step - being froth treatment.
Flotation cell froth is not only lower in grade but it also is the most stubborn component of the fresh feed bitumen, perhaps, because of oil-wet clays, emulsified water, or the presence of functional groups on the surface of the bitumen that makes it more hydrophilic than clean bitumen. Returning this slow-floating and difficult-to-separate material to the feed and to the PSC, means that the PSC must float two very different bitumen streams. One stream is the fresh feed with relatively fast-floating and clean separating bitumen, while the other is the middlings recycle, with its stubborn slow-floating bitumen aggregates. The PSC must, as a consequence, be operated as a compromise to both of these feed components. It cannot be pulled, i.e. operated in a manner that results in a high mass recovery to the froth, as hard as it could if only fresh feed was present.
Rather, it must be operated more slowly so that only the grade-acceptable portion of the middlings stream reports to the froth, lest all of the middlings is recovered and the overall grade of the PSC
froth drops below froth treatment feed quality standards. This common configuration, therefore, results in lower PSC bitumen recovery because it cannot be pulled as hard as it could if the middlings froth was not recycled.
All flotation cells require energy in some form to work. To date, the most common flotation device used in the Canadian oil sands is the mechanical cell that employs a rotating mixer (rotor) and a stationary assembly (stator) to prevent vortexing within the flotation cell.
Air is passed into the cell to provide a mechanism for the hydrophobic bitumen to attach and rise to the surface, where the froth is collected in troughs or launders. The mixing energy imparted by the rotor brings gas bubbles in contact with bitumen so the bitumen droplets or particles can be collected and separated from the sand and water. Electrical energy converted to mechanical energy by the motor, sheaves, gear reducers, and rotor is necessary to mix the slurry and collect the bitumen on the gas bubbles so the bitumen can be separated and recovered out of the slurry.
Other flotation devices that are of potential for use in the oil sands also require energy to work. Feed-slurry-aeration cells, i.e. external gas contacting flotation cells employ the pressure drop across a slurry flow restriction to impart shear energy to the slurry-gas mixture and, thus, provide the energy needed for bitumen to overcome bubble surface tension and laminar flow and collect on the bubble. Colunm cells use less energy within the cell, but require the slurry to be pumped many metres vertically so the counter-current flow of rising gas bubbles versus the settling sand and bitumen can be established for the required stage retention time. This energy, whether it is in the form of a motor-rotor assembly or pumps, is an operating cost penalty for the operations in the form of consumed electricity, consequent environmental emissions, and wear on equipment that will require regular maintenance.
There is, therefore, a need to improve the aforesaid compromised prior art processes, which improvement would result in an operation that results in a higher mass recovery to the froth and enhanced floating rate of the bitumen aggregates of the middlings recycle.
Oil sand extraction plant processes that employ a PSC must pump bitumen slurry into the PSC and which, thus, is many metres in height. A typical PSC would be 20 to 30 metres in diameter and over 30 metres tall. The slurry within the PSC, therefore, represents considerable potential energy that can be used for slurry transport and, innovatively, to power a flotation machine. It is an object of the present invention to exploit the potential energy contained within a PSC or any other step in an oil sands flowsheet where bitumen slurry is high relative to either grade or sub-grade structures for the purposes of powering a flotation device.
SUMMARY OF THE INVENTION
The present invention in one aspect provides for a solution to the recovery and grade problem created by the aforesaid prior art compromise by upgrading the middlings flotation froth separately from the PSC to an acceptable grade and then send it directly to froth treatment. To do this, the roughing middlings froth is floated again in a cleaning stage. This is not used anywhere in the Canadian oil sands. The invention utilizes the use of one or more cleaning stages for the purposes of increasing the bitumen content of the final froth stream.
A cleaning stage is defmed as the re-floating of froth from a middlings or a PSC tailings flotation circuit or from a previous cleaning stage. It is, therefore, the second, third, etc.
flotation step of a bitumen froth with the goal of upgrading that stream in terms of its bitumen content or grade.
Accordingly, in one aspect, the invention provides an oil sand bitumen flotation process comprising (i) feeding an aerated slurry comprising bitumen, sand, clay and water to a primary separation cell to produce a middlings stream, (ii) feeding said middlings stream to roughing middlings means to produce a roughing middlings froth;
(iii) feeding said roughing middlings froth to cleaning means to produce upgraded bitumen froth and collecting said upgraded bitumen froth.
Preferably, the process fiuther comprises feeding the upgraded bitumen froth to froth treatment means.
In a further aspect, the invention provides an oil sand bitumen flotation process comprising (i) feeding an aerated slurry comprising bitumen, sand, clay and water to a primary separation cell;
(ii) removing aerated bitumen from said primary separation cell;
(iii) removing said sand and clay as tailings from said primary separation cell;
(iv) removing a middlings stream from said primary separation cell;
(v) feeding said middlings stream to flotation means;
(vi) removing a first middlings froth from said flotation means;
(vii) removing tailings from said flotation means;
characterized in feeding said first middlings froth of step (vi) to first flotation cleaning means to produce an upgraded bitumen stream.
The process, as hereinabove defined, preferably has the flotation means selected from flotation column means and flotation contact cell means.
In one aspect, the invention provides a process wherein the flotation means is a flotation column means and further comprises feeding the tailings of step (vii) constituting flotation column tailings to first contract cell means in series with the flotation column, to produce a first contact cell froth and feeding the first contact cell froth to second flotation cleaning means to produce an upgraded bitumen stream.
In a further aspect, the invention provides a process further comprising feeding the sand and clay tailings of step (iii) to hydrocyclone means to produce a cyclone overflow and feeding the overflow to second contact cell means to produce a second contact cell froth, and feeding the second contact cell froth to third floatation cleaning means to produce an upgraded bitumen stream.
In a further aspect, the invention provides a process as hereinabove defmed further comprising removing primary separation cell froth from the primary separation cell and feeding said primary separation cell froth to fourth flotation cleaning means to produce an upgraded bitumen stream.
In preferred embodiments, the invention as hereinabove defmed provides a process wherein the first, second, third and fourth flotation cleaning means are the same.
In further embodiments, the invention provides a process wherein the upgraded bitumen stream is fed to froth treatment means to produce upgraded bitumen.
By the term "upgraded bitumen stream" is mean enhancement of the bitumen grade, either by % by weight or volume of the stream relative to the input froth grade.
In this specification and claims the term "contact cells" means one or more, used in series or parallel, of the feed-slurry-aeration family of froth flotation devices.
The flotation cleaning means may comprise one or more flotation cleaning units, which is defined herein as a unit that re-floats froth from a previous flotation stage, which stage can be mechanical, column, feed-slurry-aeration, or a primary separation device.
Cleaning the froth from a middlings or PSC tailings stream means that the quality, i.e.
bitumen, water, mineral content, can be improved so the stream can be sent to froth treatment and not recycled back to the PSC. This means that the PSC can be pulled harder, solely in response to the fresh feed, and not held back for fear of recovering excessive amounts of low-grade middlings to the froth, which would reduce grade and create downstream problems.
Pulling the PSC harder, and pulling the middlings and PSC tailings flotation circuits according to the dynamics of their systems, will result in higher overall bitumen recoveries.
It will be readily appreciated that bitumen recovery, at acceptable grade, is the goal of the extraction plant.
In a further aspect, the invention provides an oil sand bitumen flotation circuit apparatus comprising (i) a primary separation cell, (ii) means for feeding an aerated slurry comprising bitumen, sand, clay and water to said primary separation cell to produce a middlings stream, (iii) roughing middlings means, (iv) means for feeding said middlings stream to said roughing middlings means to produce a roughing middlings froth;
(v) cleaning means, (vi) means for feeding said roughing middlings froth to said cleaning means to produce upgraded bitumen froth; and (vii) means for collecting said upgraded bitumen froth.
In a further aspect, the invention provides an apparatus further comprising (viii) froth treatment means; and (ix) means for feeding said upgraded bitumen froth to said froth treatment means.
In a further aspect, the invention provides an oil sand bitumen flotation circuit apparatus comprising (i) a primary separation cell, (ii) means for feeding an aerated slurry comprising bitumen, sand, clay and water to a primary separation cell;
(iii) means for removing aerated bitumen from said primary separation cell;
(iv) means for removing said sand and clay as tailings from said primary separation cell;
(v) means for removing a middlings stream from said primary separation cell;
(vi) flotation means;
(vii) means for feeding said middlings stream to said flotation means;
(viii) means for removing a first middlings froth from said flotation means;
(ix) means for removing tailings from said flotation means;
characterized in having (x) a first flotation cleaning means; and (xi) means for feeding said first middlings froth of step (vi) to said first flotation cleaning means to produce an upgraded bitumen stream.
In preferred embodiments the flotation means is selected from flotation column means and flotation contact cell means.
In further embodiments, the invention provides an apparatus wherein said flotation means is flotation column means and further comprising (xii) first contact cell means, (xiii) second contact cell means; and (xiv) means for feeding said tailings of step (vii) constituting flotation column tailings to said first contract cell means in series with said flotation column means, to produce a first contact cell froth and feeding said first contact cell froth to said second flotation cleaning means to produce an upgraded bitumen stream.
In a further aspect, the invention provides an apparatus as hereinabove defmed further comprising (xv) hydrocyclone means, (xvi) third flotation cleaning means and (xvii) means for feeding said sand and clay tailings of step (iii) to said hydrocyclone means to produce a cyclone overflow, and feeding said overflow to said second contact cell means to produce a second contact cell froth, and feeding said second contact cell froth to said third floatation cleaning means to produce an upgraded bitumen stream.
In a further aspect, the invention provides an apparatus as hereinabove defmed further comprising (xviii) fourth flotation cleaning means and (xiv) means for removing primary separation cell froth from said primary separation cell and feeding said primary separation cell froth to said fourth flotation cleaning means to produce an upgraded bitumen stream.
In a further aspect, the invention provides an apparatus as hereinabove defined wherein two or more of said first, second, third and fourth flotation cleaning means are the same.
In a further aspect, the invention provides an apparatus as hereinabove defmed further comprising (xx) froth treatment means and (xxi) means for feeding said upgraded bitumen stream to said froth treatment means to produce upgraded bitumen.
In a further aspect, the invention provides an oil sand bitumen flotation process comprising (i) feeding an aerated slurry comprising bitumen, sand, clay and water to a primary separation cell to produce a middlings stream;
(ii) feeding said middlings stream to flotation means to produce a middlings froth and middlings tailings, characterized in feeding said middlings stream under gravity flow to said flotation means.
In a further aspect, the invention provides a process as hereinabove defined wherein the flotation means is selected from flotation column means and flotation contact cell means.
In a further aspect, the invention provides a process as hereinabove defined wherein the flotation means is flotation column means and which process produces a flotation column froth and flotation column tailings.
In a further aspect, the invention provides a process as hereinabove defmed wherein the flotation means is flotation contact cell means.
In yet a further aspect, the invention provides a process as hereinabove defmed further comprising feeding the flotation column tailings to flotation contact cell means to produce a flotation contact cell froth and contact cell tailings.
In a further aspect, the invention provides an oil sand bitumen flotation circuit comprising (i) a primary separation cell;
(ii) feeding an aerated slurry comprising bitumen, sand, clay and water to said primary separation cell to produce a middlings stream;
(iii) flotation means;
(iv) means for feeding said middlings stream to said flotation means to produce a middlings froth and middlings tailings, characterized in (v) means for feeding said middlings stream under gravity flow to said flotation means.
In a further aspect, the invention provides an apparatus as hereinabove defmed wherein the flotation means is selected from flotation column means and flotation contact cell means.
In a further aspect, the invention provides an apparatus as hereinabove defmed wherein the flotation means is flotation column means.
In a further aspect, the invention provides an,apparatus as hereinabove defmed wherein the flotation means is flotation contact cell means.
BRIEF DESCRIPTION OF THE DRAWINGS
In order that the invention may be better understood, preferred embodiments will now be described, by way of example only, wherein Figs. 1 and 2 are diagrammatic representations of oil sand bitumen flotation processes and apparatus according to the prior art;
Figs. 3 and 4 are diagrammatic representations of oil sand bitumen flotation processes and apparatus according to the invention, and wherein the same numerals denote like parts.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
With reference to Fig. 1, this shows generally as 10, a prior art bubble-particle collection circuit, showing the sources of energy necessary for froth collection, having a pair of primary separation cells 12 to which is fed fresh feed 14 and from which is obtained bitumen froth 16, non-segregating tailings 18 and 1 middlings take-off stream 20.
In this embodiment, the collection energy comes from mechanical agitation imported to the slurry within the plurality of mechanical cells 22 each having a spinning rotor (not shown). This step requires consumption of electrical energy, but does not utilize the potential energy held by the slurry in the upstream process when it is present in the primary separation cells 12, in the formation of the bitumen/gas bubble froth in mechanical cells 22. Further, pumps 24 are required to feed middlings stream 20 and non-segregated tailings froth stream 26.
Fig. 2 shows, generally as 100, an alternative prior art bubble-particle collection circuit apparatus and process requiring input energy, but not using the potential energy stored in the slurry present in the upstream primary separation cells 12. In this embodiment, mechanical cells 22 have been replaced by column cells 28 requiring column feed pumps 30, which provide electrical/mechanical energy to get the slurry and gas bubbles can manifest and create the conditions for bubble-particle froth collection.
An embodiment of a cleaning flotation circuit according to the invention can be seen in Fig. 3 wherein there are three roughing flotation stages represented. The primary separation cell receives fresh feed from the hydrotransport system or some other feed preparation step. A middlings stream is used for level control of the PSC and to send a dilute slurry stream to the flotation circuit where additional bitumen is recovered.
The first flotation step is a flotation column and the tailings of the column flow to the next flotation stage, being a contact cell. The tailings from the PSC are pumped to a hydrocyclone stage with the cyclone overflow being treated in another flotation a contact cell.
As mentioned, hereinbefore, current practice in the Canadian oil sands is to recycle the froth from the roughing stages back to the PSC. In this embodiment, however, the froth from all three roughing stages reports to a cleaning stage where the bitumen content is upgraded enough so it can be sent directly to the froth treatment process. If one stage of cleaning is not enough then multiple stages can be used. There are a variety of options for handling the tailings from the cleaning steps.
In more detail, Fig. 3, shows generally as 200, an oil sand bitumen flotation cleaning circuit apparatus and process according to the invention.
Circuit 200 has primary separation cell 12 to which is fed fresh feed 14 and from which bitumen froth 16, non-segregating tailings 18 and middlings tailings 20 are run off.
Middlings stream 20 is fed to a first flotation stage feed slurry aeration column cell 32. Froth 31 from stage 32 is fed to a combined flotation stage cell 33.
Tailings from stage 32 are passed to a second flotation stage contact cell 34 to provide froth 35 which is combined with froth 31 and passed also to combined flotation stage cell 33.
Tailings from cell 34 exit circuit 200.
PSC 12 tailings are pumped to hydrocyclone 36 wherein non-segregating tailings exit circuit 200. Hydrocyclone overflow process stream 39 from hydrocyclone 36 is fed to a third flotation stage cell 38 to produce non-segregated tailings stream 41 which exits circuit 200 and froth 42, which is combined with froth streams 31 and 35 for transfer to combined flotation stage cell 33. Tailings from cell 33 are recycled through contact 44 to PSC
middlings stream 20 while cell 33 froth 46 is fed to treatment unit 46.
Bitumen froth 46 is of a sufficient quality to report to froth treatment and not be recycled to the PSC.
It should be noted that the incorporation of cleaning stage 33 provides the most preferred embodiment of the present invention.
In the aspect of the present invention directed to use of gravity powered flotation as hereinbefore defined, and described hereinbelow, the primary separation cell receives fresh feed from the hydrotransport system or some other feed preparation step. A
middlings stream is used for level control of the PSC and to send a dilute slurry stream to the flotation circuit where additional bitumen is recovered. The first flotation step is a flotation column and the tailings of the column flow to the next flotation stage, being a contact cell.
The tailings from the PSC are pumped to a hydrocyclone stage with the cyclone overflow being treated in another contact cell flotation cell. The two flotation stages on the PSC
middlings stream exploit the potential energy of the PSC slurry. The column requires no pump and, hence, no energy to get the slurry into the cell so the counter-current flow within the column can be established. Similarly, the contact cell stage after the column utilizes the potential energy, i.e.
hydrostatic head within the column to create a pressure drop across a feed restriction so the shear field necessary for bitumen collection can be established. No pump is required.
In more detail, Fig. 4 shows generally as 300 a gravity powered flotation circuit apparatus and process according to the invention having a pair of primary separation cells 12 fed with fresh food 14 and which provides between froth 16, PSC tailings 18 and middlings stream 20.
Circuit 300 has a feed slurry aeration cell 50 as a first flotation stage, and a contact cell 52 as a second flotation stage. Hydrocyclones 54 are used to treat tailings 18 to provide hydrocyclones overflowers 56. Cells 50 produces first flotation stage tailings 58 which are fed to contact cells 52, whereby second flotation tailings 60 are passed as combined flotation tailings 62 to thickener 64, which produces non-segregating tailings built from the coarse sand obtained from the hydrocyclone underflow and thickener underflow.
Hydrocyclone flow 56 is treated in flotation stage 68 to provide tailings 70 and froth 72 which is fed back to PSC 12, while hydrocyclone underflow of coarse sand and a little water exit circuit 300.
First and second stage froths 72 and 74, respectively, are combined and recycled with primary feed 14 to PSC 12.
The elevation of the hydrocyclones 54 treating PSC tails 18 provides enough hydrostatic head, i.e. potential energy to drive contactor 68 of the third flotation stage. The contractor is that part of a contact flotation cell wherein gas bubbles and slurry are in intimate contact before, through, and after a shear field generated by a pressure drop across a restriction in the feed pipe.
The columns and Contact Cells flotation machines used in this embodiment uses no pumps, rotors, electric motors, or dedicated energy of any kind for the collection of bitumen and its separation, via the froth interface. The energy needed for these cells to work, defined as the energy needed for the bubble-particle collection process to occur in a reasonable amount of time, is provided exclusively by potential energy stored in the slurry as a result of transporting the slurry to either the PSC 12 or to hydrocyclones 54. These are true gravity powered flotation devices and circuits. Flotation columns or any of the family of feed-slurry-aeration devices, also known as external gas contacting flotation devices on the market, can be used within a gravity powered circuit similar to that as described herein.
The essence of the present invention is the exploitation of gravity in the form of slurry potential energy, as a result of other processes, such as primary separation in a PSC, to enable the bubble-particle, or droplet collection process, in one or more flotation stages. The invention includes flotation circuits wherein the aeration of the slurry requires an external energy source and it, also, includes circuits that are self-aspirating, i.e.
having no blowers or compressors.
The invention provides in one aspect the benefits of lower energy and operating costs for the oil sand producers. _ Table 1 shows an example of the energy savings of a gravity powered over a conventional mechanical cell circuit for a new oil sand project. Savings in power alone approach $1 million per year. Added to this sum would be capital savings from fewer pumps or electric motors; maintenance on the pumps, rotors, or stators; and higher availability of the flotation circuit which is probably the biggest revenue argument of all.
Mechanical cells Contact Columns/cells Contact Contact Column (2) Cells (4) Cell volume 160 m3 Cell diameter 7.0 m 7.0 6.0 m Effective cell footprint (assume square) 49.0 m2 49.0 36.0 m2 $/kWh 0.05 Availability 95%
Total #ofcells 15 2 4 6 Footprint 735 mZ 98 .144 242 m2 Jg 1.3 cm/s 0.6 0.6 cm/s Air 27,016 m3/h 1,663 2,443 4,105 m3/h Agitation? Y No No kW_AIR 500 500 kW_AGITATION 1,950 N/A
kWh per year 20,388,900 4,161,000 Annual power cost $1,019,445 $208,050 Power savings $811,395 The present invention in a.further aspect provides the benefit that cleaning the froth from a middlings or PSC tailings stream means that the quality (bitumen, water, mineral content) can be improved so the stream can be sent to froth treatment and not recycled back to the PSC. This means that the PSC can be pulled harder, solely in response to the fresh feed, and not held back for fear of recovering excessive amounts of low grade middlings to the froth, which would reduce grade and create downstream problems. Pulling the PSC
harder, and pulling the middlings and PSC tailings flotation circuits according to the dynamics of their system, will result in higher overall bitumen recoveries.
Bitumen recovery, at acceptable grade, is the goal of the extraction plant.
Table 2 illustrates what a 1% increase in bitumen recovery would be worth at today's oil prices and for an operation producing 100,000 barrels per day of oil.
Additional barrels from higher recovery 1,000 Discount rate 9%
Price per barrel $60 Operating cost per barrel $20 Plant availability 95%
Year Income Expense Net NPV
1 $0 $0 2 $13,870,000 $0 $13,870,000 3 $13,870,000 $0 $13,870,000 4 $13,870,000 $0 $13,870,000 $13,870,000 $0 $13,870,000 $41,224,692 6 $13,870,000 $0 $13,870,000 7 $13,870,000 $0 $13,870,000 8 $13,870,000 $0 $13,870,000 9 $13,870,000 $0 $13,870,000 $13,870,000 $0 $13,870,000 $76,288,142 Although this disclosure has described and illustrated certain preferred embodiments of the invention, it is to be understood that the invention is not restricted to those particular 5 embodiments. Rather, the invention includes all embodiments, which are functional or mechanical equivalence of the specific embodiments and features that have been described and illustrated.
Claims (27)
1. An oil sand bitumen flotation process comprising (i) feeding an aerated slurry comprising bitumen, sand, clay and water to a primary separation cell to produce a middlings stream, (ii) feeding said middlings stream to roughing middlings means to produce a roughing middlings froth;
(iii) feeding said roughing middlings froth to cleaning means to produce upgraded bitumen froth and collecting said upgraded bitumen froth.
(iii) feeding said roughing middlings froth to cleaning means to produce upgraded bitumen froth and collecting said upgraded bitumen froth.
2. A process as claimed in claim 1 further comprising feeding said upgraded bitumen froth to froth treatment means.
3. An oil sand bitumen flotation process comprising (i) feeding an aerated slurry comprising bitumen, sand, clay and water to a primary separation cell;
(ii) removing aerated bitumen from said primary separation cell;
(iii) removing said sand and clay as tailings from said primary separation cell;
(iv) removing a middlings stream from said primary separation cell;
(v) feeding said middlings stream to flotation means;
(vi) removing a first middlings froth from said flotation means;
(vii) removing tailings from said flotation means;
characterized in feeding said first middlings froth of step (vi) to first flotation cleaning means to produce an upgraded bitumen stream.
(ii) removing aerated bitumen from said primary separation cell;
(iii) removing said sand and clay as tailings from said primary separation cell;
(iv) removing a middlings stream from said primary separation cell;
(v) feeding said middlings stream to flotation means;
(vi) removing a first middlings froth from said flotation means;
(vii) removing tailings from said flotation means;
characterized in feeding said first middlings froth of step (vi) to first flotation cleaning means to produce an upgraded bitumen stream.
4. A process as claimed in claim 3 wherein said flotation means is selected from flotation column means and flotation contact cell means.
5. A process as claimed in claim 4 wherein said flotation means is a flotation column means and further comprising feeding said tailings of step (vii) constituting flotation column tailings to first contract cell means in series with said flotation column, to produce a first contact cell froth and feeding said first contact cell froth to second flotation cleaning means to produce an upgraded bitumen stream.
6. A process as claimed in any one of claims 3 to 5 further comprising feeding said sand and clay tailings of step (iii) to hydrocyclone means to produce a cyclone overflow, and feeding said overflow to second contact cell means to produce a second contact cell froth, and feeding said second contact cell froth to third floatation cleaning means to produce an upgraded bitumen stream.
7. A process as claimed in any one of claims 3 to 6 further comprising removing primary separation cell froth from said primary separation cell and feeding said primary separation cell froth to fourth flotation cleaning means to produce an upgraded bitumen stream.
8. A process as claimed in any one of claims 3 to 7 wherein said first, second, third and fourth flotation cleaning means are the same.
9. A process as claimed in any one of claims 3 to 8 wherein said upgraded bitumen stream is fed to froth treatment means to produce upgraded bitumen.
10. An oil sand bitumen flotation circuit apparatus comprising (i) a primary separation cell, (ii) means for feeding an aerated slurry comprising bitumen, sand, clay and water to said primary separation cell to produce a middlings stream, (iii) roughing middlings means, (iv) means for feeding said middlings stream to said roughing middlings means to produce a roughing middlings froth;
(v) cleaning means, (vi) means for feeding said roughing middlings froth to said cleaning means to produce upgraded bitumen froth; and (vii) means for collecting said upgraded bitumen froth.
(v) cleaning means, (vi) means for feeding said roughing middlings froth to said cleaning means to produce upgraded bitumen froth; and (vii) means for collecting said upgraded bitumen froth.
11. Apparatus as claimed in claim 10 further comprising (viii) froth treatment means; and (ix) means for feeding said upgraded bitumen froth to said froth treatment means.
12. An oil sand bitumen flotation circuit apparatus comprising (i) a primary separation cell, (ii) means for feeding an aerated slurry comprising bitumen, sand, clay and water to a primary separation cell;
(iii) means for removing aerated bitumen from said primary separation cell;
(iv) means for removing said sand and clay as tailings from said primary separation cell;
(v) means for removing a middlings stream from said primary separation cell;
(vi) flotation means;
(vii) means for feeding said middlings stream to said flotation means;
(viii) means for removing a first middlings froth from said flotation means;
(ix) means for removing tailings from said flotation means characterized in (x) having a first flotation cleaning means; and (xi) means for feeding said first middlings froth of step (vi) to said first flotation cleaning means to produce an upgraded bitumen stream.
(iii) means for removing aerated bitumen from said primary separation cell;
(iv) means for removing said sand and clay as tailings from said primary separation cell;
(v) means for removing a middlings stream from said primary separation cell;
(vi) flotation means;
(vii) means for feeding said middlings stream to said flotation means;
(viii) means for removing a first middlings froth from said flotation means;
(ix) means for removing tailings from said flotation means characterized in (x) having a first flotation cleaning means; and (xi) means for feeding said first middlings froth of step (vi) to said first flotation cleaning means to produce an upgraded bitumen stream.
13. Apparatus as claimed in claim 12 wherein said flotation means is selected from flotation column means and flotation contact cell means.
14. Apparatus as claimed in claim 13 wherein said flotation means is flotation column means and further comprising (xii) first contact cell means, (xiii) second contact cell means and (xiv) means for feeding said tailings of step (vii) constituting flotation column tailings to said first contract cell means in series with said flotation column means, to produce a first contact cell froth and feeding said first contact cell froth to said second flotation cleaning means to produce an upgraded bitumen stream.
15. Apparatus as claimed in any one of claims 12 to 14 further comprising (xv) hydrocyclone means, (xvi) third flotation cleaning means and (xvii) means for feeding said sand and clay tailings of step (iii) to said hydrocyclone means to produce a cyclone overflow, and feeding said overflow to said second contact cell means to produce a second contact cell froth, and feeding said second contact cell froth to said third floatation cleaning means to produce an upgraded bitumen stream.
16. Apparatus as claimed in any one of claims 12 to 15 further comprising (xviii) fourth flotation cleaning means and (xiv) means for removing primary separation cell froth from said primary separation cell and feeding said primary separation cell froth to said fourth flotation cleaning means to produce an upgraded bitumen stream.
17. Apparatus as claimed in any one of claims 12 to 16 wherein two or more of said first, second, third and fourth flotation cleaning means are the same.
18. Apparatus as claimed in any one of claims 12 to 17 further comprising (xx) froth treatment means and (xxi) means for feeding said upgraded bitumen stream to said froth treatment means to produce upgraded bitumen.
19. An oil sand bitumen flotation process comprising (i) feeding an aerated slurry comprising bitumen, sand, clay and water to a primary separation cell to produce a middlings stream;
(ii) feeding said middlings stream to flotation means to produce a middlings froth and middlings tailings, characterized in feeding said middlings stream under gravity flow to said flotation means.
(ii) feeding said middlings stream to flotation means to produce a middlings froth and middlings tailings, characterized in feeding said middlings stream under gravity flow to said flotation means.
20. A process as claimed in claim 19 wherein said flotation means is selected from flotation column means and flotation contact cell means.
21. A process as claimed in claim 20 wherein said flotation means is flotation column means and producing a flotation column froth and flotation column tailings.
22. A process as claimed in claim 20 wherein said flotation means is flotation contact cell means.
23. A process as claimed in claim 21 further comprising feeding said flotation column tailings to flotation contact cell means to produce a flotation contact cell froth and contact cell tailings.
24. An oil sand bitumen flotation circuit comprising (i) a primary separation cell;
(ii) feeding an aerated slurry comprising bitumen, sand, clay and water to said primary separation cell to produce a middlings stream;
(iii) flotation means;
(iv) means for feeding said middlings stream to said flotation means to produce a middlings froth and middlings tailings, characterized in (v) means for feeding said middlings stream under gravity flow to said flotation means.
(ii) feeding an aerated slurry comprising bitumen, sand, clay and water to said primary separation cell to produce a middlings stream;
(iii) flotation means;
(iv) means for feeding said middlings stream to said flotation means to produce a middlings froth and middlings tailings, characterized in (v) means for feeding said middlings stream under gravity flow to said flotation means.
25. Apparatus as claimed in claim 24 wherein said flotation means is selected from flotation column means and flotation contact cell means.
26. Apparatus as claimed in claim 25 wherein said flotation means is flotation column means.
27. Apparatus as claimed in claim 25 wherein said flotation means is flotation contact cell means.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA 2581992 CA2581992A1 (en) | 2007-03-08 | 2007-03-08 | Gravity powered and cleaning flotation circuits |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA 2581992 CA2581992A1 (en) | 2007-03-08 | 2007-03-08 | Gravity powered and cleaning flotation circuits |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2581992A1 true CA2581992A1 (en) | 2008-09-08 |
Family
ID=39747227
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 2581992 Abandoned CA2581992A1 (en) | 2007-03-08 | 2007-03-08 | Gravity powered and cleaning flotation circuits |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA2581992A1 (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2017079276A1 (en) * | 2015-11-03 | 2017-05-11 | Magglobal, Llc | Methods, devices, systems and processes for upgrading iron oxide concentrates using reverse flotation of silica at a natural ph |
| CN120394205A (en) * | 2025-07-01 | 2025-08-01 | 中南大学 | A flotation column with multi-stage mineralization |
-
2007
- 2007-03-08 CA CA 2581992 patent/CA2581992A1/en not_active Abandoned
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2017079276A1 (en) * | 2015-11-03 | 2017-05-11 | Magglobal, Llc | Methods, devices, systems and processes for upgrading iron oxide concentrates using reverse flotation of silica at a natural ph |
| US10201816B2 (en) | 2015-11-03 | 2019-02-12 | Magglobal, Llc | Methods, devices, systems and processes for upgrading iron oxide concentrates using reverse flotation of silica at a natural pH |
| CN120394205A (en) * | 2025-07-01 | 2025-08-01 | 中南大学 | A flotation column with multi-stage mineralization |
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