CA2937452C - Method of dewatering of a tailings stream - Google Patents
Method of dewatering of a tailings stream Download PDFInfo
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- CA2937452C CA2937452C CA2937452A CA2937452A CA2937452C CA 2937452 C CA2937452 C CA 2937452C CA 2937452 A CA2937452 A CA 2937452A CA 2937452 A CA2937452 A CA 2937452A CA 2937452 C CA2937452 C CA 2937452C
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D21/00—Separation of suspended solid particles from liquids by sedimentation
- B01D21/01—Separation of suspended solid particles from liquids by sedimentation using flocculating agents
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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
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/52—Treatment of water, waste water, or sewage by flocculation or precipitation of suspended impurities
- C02F1/5209—Regulation methods for flocculation or precipitation
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/52—Treatment of water, waste water, or sewage by flocculation or precipitation of suspended impurities
- C02F1/54—Treatment of water, waste water, or sewage by flocculation or precipitation of suspended impurities using organic material
- C02F1/56—Macromolecular compounds
-
- 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
- C02F11/147—Treatment of sludge; Devices therefor by de-watering, drying or thickening with addition of chemical agents using organic substances
-
- C—CHEMISTRY; METALLURGY
- C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
- C10G—CRACKING HYDROCARBON OILS; PRODUCTION OF LIQUID HYDROCARBON MIXTURES, e.g. BY DESTRUCTIVE HYDROGENATION, OLIGOMERISATION, POLYMERISATION; RECOVERY OF HYDROCARBON OILS FROM OIL-SHALE, OIL-SAND, OR GASES; REFINING MIXTURES MAINLY CONSISTING OF HYDROCARBONS; REFORMING OF NAPHTHA; MINERAL WAXES
- C10G1/00—Production of liquid hydrocarbon mixtures from oil-shale, oil-sand, or non-melting solid carbonaceous or similar materials, e.g. wood, coal
- C10G1/04—Production of liquid hydrocarbon mixtures from oil-shale, oil-sand, or non-melting solid carbonaceous or similar materials, e.g. wood, coal by extraction
- C10G1/045—Separation of insoluble materials
-
- C—CHEMISTRY; METALLURGY
- C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
- C10G—CRACKING HYDROCARBON OILS; PRODUCTION OF LIQUID HYDROCARBON MIXTURES, e.g. BY DESTRUCTIVE HYDROGENATION, OLIGOMERISATION, POLYMERISATION; RECOVERY OF HYDROCARBON OILS FROM OIL-SHALE, OIL-SAND, OR GASES; REFINING MIXTURES MAINLY CONSISTING OF HYDROCARBONS; REFORMING OF NAPHTHA; MINERAL WAXES
- C10G1/00—Production of liquid hydrocarbon mixtures from oil-shale, oil-sand, or non-melting solid carbonaceous or similar materials, e.g. wood, coal
- C10G1/04—Production of liquid hydrocarbon mixtures from oil-shale, oil-sand, or non-melting solid carbonaceous or similar materials, e.g. wood, coal by extraction
- C10G1/047—Hot water or cold water extraction processes
-
- 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
- C10G2300/00—Aspects relating to hydrocarbon processing covered by groups C10G1/00 - C10G99/00
- C10G2300/10—Feedstock materials
- C10G2300/1033—Oil well production fluids
-
- 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
- C10G2300/00—Aspects relating to hydrocarbon processing covered by groups C10G1/00 - C10G99/00
- C10G2300/20—Characteristics of the feedstock or the products
- C10G2300/201—Impurities
- C10G2300/208—Sediments, e.g. bottom sediment and water or BSW
Landscapes
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Organic Chemistry (AREA)
- Life Sciences & Earth Sciences (AREA)
- Environmental & Geological Engineering (AREA)
- Hydrology & Water Resources (AREA)
- Water Supply & Treatment (AREA)
- General Chemical & Material Sciences (AREA)
- Oil, Petroleum & Natural Gas (AREA)
- Wood Science & Technology (AREA)
- Treatment Of Sludge (AREA)
- Separation Of Suspended Particles By Flocculating Agents (AREA)
Abstract
A method for dewatering oil sands tailings streams, in-line and in real time, measures in-line one or more of solids concentration, clay content and flow rate of a tailings stream and a concentration of flocculant of a flocculant-containing stream. After combining an amount of the flocculant-containing stream with the tailings stream, the resulting flocculant-enriched tailings stream is subjected to shear, based initially upon the measurements taken, and is mixed in a dynamic shear device to obtain flocculated tailings. Images or chord lengths of the flocculated tailings are obtained continuously inline in real time prior to a separation step. Signals indicative of a flocculation state of the flocculated tailings are derived in-line in real time using the images, the chord-lengths, or both, for automatically controlling, in real time, the shear applied for controlling dewaterability and yield strength of the flocculated tailings.
Description
METHOD OF DEWATERING OF A TAILINGS STREAM
The present invention relates to a method of dewatering of a tailings stream, in particular oil sands tailings.
Oil sands mining operations generate significant volumes of so-called 'tailings' that pose unique challenges for water recovery and land reclamation. Currently, the legacy Mature Fine Tailings (MFT) or continuously produced Fluid Fine Tailings (FFT) are stored in tailings ponds and are typically periodically transported without treatment.
Treatment of tailings can lead to reduced volumes of tailings and to faster mine closure and reclamation of the disturbed land.
Several treatments have been suggested. A potentially effective tailings treatment option is flocculation.
Flocculation uses flocculants that help the clay/fines in the tailings to form large aggregates which settle thereby leaving the water for reclamation.
An example of a method for monitoring and controlling the dewatering of oil sands tailings has been described in US20160100135. US20160100135 discloses an in-line monitoring method, wherein an image capture device is positioned in a flow of flocculated oil sands tailing through a pipeline for acquiring one or more images of the flocculated oil sands tailing; collecting the one or more images; and analyzing the one or more images to ensure production of alleged optimum floc structures.
A problem of the method as described in U520160100135 is that it does not allow for inline real-time measurement of process sensitivities and disturbances including (but =
The present invention relates to a method of dewatering of a tailings stream, in particular oil sands tailings.
Oil sands mining operations generate significant volumes of so-called 'tailings' that pose unique challenges for water recovery and land reclamation. Currently, the legacy Mature Fine Tailings (MFT) or continuously produced Fluid Fine Tailings (FFT) are stored in tailings ponds and are typically periodically transported without treatment.
Treatment of tailings can lead to reduced volumes of tailings and to faster mine closure and reclamation of the disturbed land.
Several treatments have been suggested. A potentially effective tailings treatment option is flocculation.
Flocculation uses flocculants that help the clay/fines in the tailings to form large aggregates which settle thereby leaving the water for reclamation.
An example of a method for monitoring and controlling the dewatering of oil sands tailings has been described in US20160100135. US20160100135 discloses an in-line monitoring method, wherein an image capture device is positioned in a flow of flocculated oil sands tailing through a pipeline for acquiring one or more images of the flocculated oil sands tailing; collecting the one or more images; and analyzing the one or more images to ensure production of alleged optimum floc structures.
A problem of the method as described in U520160100135 is that it does not allow for inline real-time measurement of process sensitivities and disturbances including (but =
- 2 -not limited to) variation in the clay content in the tailings feed stream and amount of flocculant injected into the tailings stream. Oil sand tailings (like other types of tailings) can have substantial variability in compositions and in case the amount of.flocculant is not optimized, this may result in ineffective flocculation or unnecessary loss of expensive flocculants. In this respect it is noted that the method as described in US20160100135 determines 'good' or 'bad' flocculation based on dewatering only, without considering the yield strength which is important for reclamation as well. Also, the method as described in US20160100135 does not account for under- or overshearing of the tailings.
Another problem of the method as described in US20160100135 is that it uses variations in the pixel brightness of the image as an estimate of the 'well flocculated' material, which can be specific to MFT/FFTs.
This value changes depending on the composition of a tailings stream (which may change over time and which may be different for different types of tailings) and which cannot be monitored dynamically in the described method.
Another issue with the known method is that the signal as generated according to the method as described in US20160100135 is insensitive between well-flocculated and oversheared state of treated tailings. After the tailings have become well flocculated the signal saturates; in this manner, the metric cannot differentiate between 'well mixed' and 'over mixed' materials.
It is an object of the present invention to solve, minimize or at least reduce one or more of the above problems.
Another problem of the method as described in US20160100135 is that it uses variations in the pixel brightness of the image as an estimate of the 'well flocculated' material, which can be specific to MFT/FFTs.
This value changes depending on the composition of a tailings stream (which may change over time and which may be different for different types of tailings) and which cannot be monitored dynamically in the described method.
Another issue with the known method is that the signal as generated according to the method as described in US20160100135 is insensitive between well-flocculated and oversheared state of treated tailings. After the tailings have become well flocculated the signal saturates; in this manner, the metric cannot differentiate between 'well mixed' and 'over mixed' materials.
It is an object of the present invention to solve, minimize or at least reduce one or more of the above problems.
- 3 -It is a further object of the present invention to provide an alternative method of monitoring and controlling the flocculation and/or dewatering of a tailings stream.
One or more of the above or other objects may be achieved according to the present invention by providing a method of dewatering of a tailings stream, in particular oil sands tailings, the method at least comprising the steps of:
(a) providing a tailings stream;
(b) measuring at least the solids concentration, the clay content and the flow rate of the tailings stream provided in step (a);
(c) providing a flocculant-containing stream;
(d) measuring the concentration of flocculant of the flocculant-containing stream as provided in step (c);
(e) combining the flocculant-containing stream provided in step (c) with the tailings stream provided in step (a) thereby obtaining a flocculant-enriched tailings stream;
(f) subjecting the flocculant-enriched tailings stream obtained in step (e) to shear and mixing in a shear device thereby obtaining flocculated tailings;
(g) separating the flocculated tailings thereby obtaining a dewatered tailings stream and a water-enriched stream;
wherein the amount of flocculant-containing stream combined in step (e) is based on the clay content of the tailings stream as measured in step (b) and the concentration of flocculant of the flocculant-containing stream as measured in step (d); and wherein the amount of shear in step (f) is selected dependent on the solids concentration, the clay content and the flow rate of the tailings stream as measured in step (b).
One or more of the above or other objects may be achieved according to the present invention by providing a method of dewatering of a tailings stream, in particular oil sands tailings, the method at least comprising the steps of:
(a) providing a tailings stream;
(b) measuring at least the solids concentration, the clay content and the flow rate of the tailings stream provided in step (a);
(c) providing a flocculant-containing stream;
(d) measuring the concentration of flocculant of the flocculant-containing stream as provided in step (c);
(e) combining the flocculant-containing stream provided in step (c) with the tailings stream provided in step (a) thereby obtaining a flocculant-enriched tailings stream;
(f) subjecting the flocculant-enriched tailings stream obtained in step (e) to shear and mixing in a shear device thereby obtaining flocculated tailings;
(g) separating the flocculated tailings thereby obtaining a dewatered tailings stream and a water-enriched stream;
wherein the amount of flocculant-containing stream combined in step (e) is based on the clay content of the tailings stream as measured in step (b) and the concentration of flocculant of the flocculant-containing stream as measured in step (d); and wherein the amount of shear in step (f) is selected dependent on the solids concentration, the clay content and the flow rate of the tailings stream as measured in step (b).
- 4 -It has surprisingly been found according to the present invention that it allows for inline real-time measurement of process sensitivities and disturbances including (but not limited to) variation in the clay content in the tailings feed stream and amount of flocculant injected into the tailings stream. As the present invention makes the amount of flocculant added dependent on the clay content of the tailings stream the flocculation process can be optimized, whilst overuse of (and hence loss of expensive) flocculant can be minimized.
A further advantage of the method according to the present invention is that the quality of the flocculated tailings can be maintained at a target flocculation state with respect to both dewatering and yield strength values using automated control of the shear in the shear device.
It has been found according to the present invention that, from a reclamation perspective, both dewatering and yield strength are important parameters. A low yield strength of the flocculated tailings may indicate slow or ineffective reclamation even with good immediate dewatering.
In step (a), a tailings stream is provided. The tailings stream is not limited in any way (in terms of composition, phase, etc.) and can be any tailings stream as obtained in mining, oil sands operations, etc.
However, preferably, the tailing stream is an oil sands tailings stream such as MFT. Also, it is preferred that the tailings stream is continuously flowing.
Preferably, the tailings stream as provided in step (a) comprises from 55 to 85 wt.% water, preferably at least 60 wt.%, more preferably at least 65 wt.%, and =
A further advantage of the method according to the present invention is that the quality of the flocculated tailings can be maintained at a target flocculation state with respect to both dewatering and yield strength values using automated control of the shear in the shear device.
It has been found according to the present invention that, from a reclamation perspective, both dewatering and yield strength are important parameters. A low yield strength of the flocculated tailings may indicate slow or ineffective reclamation even with good immediate dewatering.
In step (a), a tailings stream is provided. The tailings stream is not limited in any way (in terms of composition, phase, etc.) and can be any tailings stream as obtained in mining, oil sands operations, etc.
However, preferably, the tailing stream is an oil sands tailings stream such as MFT. Also, it is preferred that the tailings stream is continuously flowing.
Preferably, the tailings stream as provided in step (a) comprises from 55 to 85 wt.% water, preferably at least 60 wt.%, more preferably at least 65 wt.%, and =
- 5 -preferably at most 75 wt.%, more preferably at most 70 wt. %.
Further it is preferred that the tailings stream as provided in step (a) comprises from 15 to 45 wt.% solids, preferably at least 25 wt.% and preferably at most 35 wt.%. The solids in the tailings stream are typically mineral solids with a particle diameter of less than 44 micron ("fines"), as greater solids particles may have bene removed earlier. Further, in case the tailings stream is an oils sands stream, it usually contains at least 5 ppm bitumen, typically at least 10 ppm, more typically at least 15 ppm, even more typically at least ppm, sometimes even as high as 10 wt.%.
In step (b), at least the solids concentration, the 15 clay content and the flow rate of the tailings stream provided in step (a) are measured.
The person skilled in the art will readily understand that various suitable devices and methods are available for measuring the solids concentration, the clay content 20 and the flow rate.
Typically, the solids concentration is measured using an in-line densitometer, e.g. a nuclear densitometer, coriolis meter, etc. If desired, dependent on the solids concentration measured in step (b), the tailings stream may optionally be diluted to a predefined value for the solids concentration, typically between 20-40 wt.%, preferably above 25 wt.% and preferably below 35 wt.%.
Typically, the clay content is measured using spectroscopic techniques such as IR, NIR and FT-NIR. If desired, non-contacting sensors may be used. Preferably, in step (b) the clay content is measured using Near-infrared spectroscopy (NIR; 700-2500 nm), preferably using a non-contacting NIR device.
=
Further it is preferred that the tailings stream as provided in step (a) comprises from 15 to 45 wt.% solids, preferably at least 25 wt.% and preferably at most 35 wt.%. The solids in the tailings stream are typically mineral solids with a particle diameter of less than 44 micron ("fines"), as greater solids particles may have bene removed earlier. Further, in case the tailings stream is an oils sands stream, it usually contains at least 5 ppm bitumen, typically at least 10 ppm, more typically at least 15 ppm, even more typically at least ppm, sometimes even as high as 10 wt.%.
In step (b), at least the solids concentration, the 15 clay content and the flow rate of the tailings stream provided in step (a) are measured.
The person skilled in the art will readily understand that various suitable devices and methods are available for measuring the solids concentration, the clay content 20 and the flow rate.
Typically, the solids concentration is measured using an in-line densitometer, e.g. a nuclear densitometer, coriolis meter, etc. If desired, dependent on the solids concentration measured in step (b), the tailings stream may optionally be diluted to a predefined value for the solids concentration, typically between 20-40 wt.%, preferably above 25 wt.% and preferably below 35 wt.%.
Typically, the clay content is measured using spectroscopic techniques such as IR, NIR and FT-NIR. If desired, non-contacting sensors may be used. Preferably, in step (b) the clay content is measured using Near-infrared spectroscopy (NIR; 700-2500 nm), preferably using a non-contacting NIR device.
=
- 6 -Typically, the flow rate is measured using a flow meter. Suitable flow meters are e.g. magnetic meters, coriolis meters, pressure drop devices, etc.
In step (c), a flocculant-containing stream is provided. The person skilled in the art will readily understand that the flocculant, the amount thereof in the flocculant-containing stream and optional other components are not particularly limited. The flocculant may be selected from a broad variety of components (or mixtures thereof). Preferably the flocculant comprises a polymeric flocculant. The flocculants may be charged or uncharged. Suitable flocculants are polyacrylamides, polyacrylates, (co)polymers of ethylene oxide, etc.
Generally, the flocculant-containing stream comprises 0.05-5 wt.% flocculant in aqueous solution (dosed at 10-5000 g/tons of dry solids), preferably 0.3-0.5 wt.%
(dosed at 500-1500 g/tons of dry solids).
In step (d), the concentration of flocculant of the flocculant-containing stream as provided in step (c) is measured. Again, the person skilled in the art will readily understand that there are many suitable devices or methods for doing so. Also, the person skilled in the art will readily understand that the concentration can be measured directly or by means of a proxy (such as viscosity) that reflects the concentration. For example, a viscometer or a rheometer can be used. Usually, in step (d) also the flow rate of the flocculant-containing stream is determined.
In step (e), the flocculant-containing stream provided in step (c) is combined with the tailings stream provided in step (a) thereby obtaining a flocculant-enriched tailings stream. The person skilled in the art will understand that this combining can be done upstream r
In step (c), a flocculant-containing stream is provided. The person skilled in the art will readily understand that the flocculant, the amount thereof in the flocculant-containing stream and optional other components are not particularly limited. The flocculant may be selected from a broad variety of components (or mixtures thereof). Preferably the flocculant comprises a polymeric flocculant. The flocculants may be charged or uncharged. Suitable flocculants are polyacrylamides, polyacrylates, (co)polymers of ethylene oxide, etc.
Generally, the flocculant-containing stream comprises 0.05-5 wt.% flocculant in aqueous solution (dosed at 10-5000 g/tons of dry solids), preferably 0.3-0.5 wt.%
(dosed at 500-1500 g/tons of dry solids).
In step (d), the concentration of flocculant of the flocculant-containing stream as provided in step (c) is measured. Again, the person skilled in the art will readily understand that there are many suitable devices or methods for doing so. Also, the person skilled in the art will readily understand that the concentration can be measured directly or by means of a proxy (such as viscosity) that reflects the concentration. For example, a viscometer or a rheometer can be used. Usually, in step (d) also the flow rate of the flocculant-containing stream is determined.
In step (e), the flocculant-containing stream provided in step (c) is combined with the tailings stream provided in step (a) thereby obtaining a flocculant-enriched tailings stream. The person skilled in the art will understand that this combining can be done upstream r
- 7 -of or in the shear device. If desired, some additional flocculant may be added after exiting the shear device.
Also, if desired the tailings stream may be pre-sheared before flocculant addition and entering the shear device.
According to the present invention, the amount of flocculant-containing stream combined in step (e) is based on the clay content of the tailings stream measured in step (b) and the concentration of flocculant of the flocculant-containing stream as measured in step (d).
Preferably, the amount of flocculant-containing stream combined in step (e) is also based on the density and/or the flow rate of the tailings stream as measured in step (b).
In step (f), the flocculant-enriched tailings stream obtained in step (e) is subjected to shear and mixing in a shear device thereby obtaining flocculated tailings. As the person skilled in the art is familiar with shear devices, this is not further described here in detail.
Usually, the shear device is a static mixer, a dynamic mixer, a series of stirred tanks, etc. Preferably, the shear device is a dynamic mixer. Examples of shear devices are:
- in-line dynamic mixers (i.e. mechanical impellers installed in-pipe) such as conventional pitched blade turbines, hydrofoil variants such as A310 (commercially available from Lightnin (Rochester, NY, US)), XE3, HE3 or Maxflo W variants (commercially available from Lightnin);
- static mixers (i.e. inserts in empty pipes with geometrics to promote mixing): Kenics (commercially available from Chemineer (US)), SMV or SMX variants (commercially available from Sulzer (Winterthur, Switzerland)), static mixers with STM elements or variants obtainable from Statiflo (Macclesfield, UK);
. ,
Also, if desired the tailings stream may be pre-sheared before flocculant addition and entering the shear device.
According to the present invention, the amount of flocculant-containing stream combined in step (e) is based on the clay content of the tailings stream measured in step (b) and the concentration of flocculant of the flocculant-containing stream as measured in step (d).
Preferably, the amount of flocculant-containing stream combined in step (e) is also based on the density and/or the flow rate of the tailings stream as measured in step (b).
In step (f), the flocculant-enriched tailings stream obtained in step (e) is subjected to shear and mixing in a shear device thereby obtaining flocculated tailings. As the person skilled in the art is familiar with shear devices, this is not further described here in detail.
Usually, the shear device is a static mixer, a dynamic mixer, a series of stirred tanks, etc. Preferably, the shear device is a dynamic mixer. Examples of shear devices are:
- in-line dynamic mixers (i.e. mechanical impellers installed in-pipe) such as conventional pitched blade turbines, hydrofoil variants such as A310 (commercially available from Lightnin (Rochester, NY, US)), XE3, HE3 or Maxflo W variants (commercially available from Lightnin);
- static mixers (i.e. inserts in empty pipes with geometrics to promote mixing): Kenics (commercially available from Chemineer (US)), SMV or SMX variants (commercially available from Sulzer (Winterthur, Switzerland)), static mixers with STM elements or variants obtainable from Statiflo (Macclesfield, UK);
. ,
- 8 -- stirred mixing tanks (i.e. vessels equipped with impellers and/or agitators): process tanks with SC-3 impellers (commercially available from Lightnin) or other dynamic mixers designed for tanks.
According to the present invention, the amount of shear in step (f) is selected dependent on the flow rate, the density and clay content of the tailings stream as measured in step (b). Usually, also the geometry of the shear device is taken into account. The amount of shear can for example be adjusted by changing the mixing speed (or the flow rate in case of a static mixer).
Advantageously, this allows for a feed-forward mechanism in the shear device based on information obtained upstream of the shear device. Similarly, a feed-back mechanism may be present based on information obtained downstream of the shear device as will be discussed below.
According to a preferred embodiment of the present invention, the flocculation state of the flocculated tailings as obtained in step (f) is determined using one or more of:
- an image capturing device, preferably a PVM (Particle Vision and Measurement; commercially available from Mettler Toledo (Columbus, Ohio, US));
- a particle size measurement device, preferably a FBRM
(Focused Beam Reflectance Measurement; commercially available from Mettler Toledo);
- the solids concentration of the tailings stream as measured in step (b); and - the clay content of the tailings stream as measured in step (b).
In this respect it is noted, that the present invention introduces the (new) concept of the
According to the present invention, the amount of shear in step (f) is selected dependent on the flow rate, the density and clay content of the tailings stream as measured in step (b). Usually, also the geometry of the shear device is taken into account. The amount of shear can for example be adjusted by changing the mixing speed (or the flow rate in case of a static mixer).
Advantageously, this allows for a feed-forward mechanism in the shear device based on information obtained upstream of the shear device. Similarly, a feed-back mechanism may be present based on information obtained downstream of the shear device as will be discussed below.
According to a preferred embodiment of the present invention, the flocculation state of the flocculated tailings as obtained in step (f) is determined using one or more of:
- an image capturing device, preferably a PVM (Particle Vision and Measurement; commercially available from Mettler Toledo (Columbus, Ohio, US));
- a particle size measurement device, preferably a FBRM
(Focused Beam Reflectance Measurement; commercially available from Mettler Toledo);
- the solids concentration of the tailings stream as measured in step (b); and - the clay content of the tailings stream as measured in step (b).
In this respect it is noted, that the present invention introduces the (new) concept of the
- 9 -'flocculation state' of flocculated tailings, at least for monitoring and controlling the dewatering and yield strength of oil sands tailings. Irrespective of this new concept being used, as the person skilled in the art is familiar with the above-mentioned measurement methods and devices to obtain the flocculation state, these measurement methods and devices are not further described here in detail. According to the present invention, the image capturing device is particularly used for the purpose of assessing the dewaterability and yield strength (by analysis of the images along with analysis of other signals such as obtained from e.g. an FBRM, a NIR device and a densitometer, to determine the flocculation state which is an estimate of the dewatering and yield strength), and the particle size measurement device for measuring the size of flocs (which is also used indirectly to help the estimation of the dewaterability and yield strength. If e.g. an FBRM is used, the direct measurement is the floc size, often called 'chord length'. The signals such as obtained from e.g. a PVM and an FBRM, in addition to the ones obtained from e.g. a NIR device and densitometer are then used to determine the flocculation state, which is an estimate of the dewatering and yield strength).
Preferably, the flocculation state of the flocculated tailings as obtained in step (f) is determined whilst in addition using an image capturing device (preferably a PVM), that is used to measure the initial dewaterability and yield strength of the tailings stream provided in step (a). This additional image capturing device may help to normalize the signal obtained using the image capturing device for determining the flocculation state of the flocculated tailings as mentioned above.
Preferably, the flocculation state of the flocculated tailings as obtained in step (f) is determined whilst in addition using an image capturing device (preferably a PVM), that is used to measure the initial dewaterability and yield strength of the tailings stream provided in step (a). This additional image capturing device may help to normalize the signal obtained using the image capturing device for determining the flocculation state of the flocculated tailings as mentioned above.
- 10 -Of course, if desired and as is preferred according to the present invention, further flocculation state determination or analysis methods may be used, e.g. on the basis of image processing (of the flocs), such as Eigenfunction, Fourier transformation, fractal dimensional analysis, variation of pixel brightness, classifiers, wavelet transformation, mean gradient energy analysis, entropy (randomness) analysis, spectral weight analysis, etc.
Also, the person skilled in the art will readily understand how to record and analyse the signals from the various instruments using a computer.
According to an especially preferred embodiment according to the present invention, the determined flocculation state is used to control (and adjust if desired) one or more of:
- the amount of shear in step (f); and - the residence time of the flocculant-enriched tailings stream in the shear device in step (f). This advantageously allows for a feedback loop to the shear device. In this respect it is noted, that the present invention - apart from introducing the concept of the 'flocculation state' of flocculated tailings as mentioned above - also introduces the concept of using the flocculation state for controlling the flocculation process. By measuring the flocculation state of the flocculated tailings it can be determined whether the flocculation has been effective and, if not, e.g. the amount of shear applied in step (f) can be controlled by increasing or decreasing the amount of shear, if appropriate.
If desired, the flocculated tailings obtained in step (f) may be transported in a pipeline to a remote
Also, the person skilled in the art will readily understand how to record and analyse the signals from the various instruments using a computer.
According to an especially preferred embodiment according to the present invention, the determined flocculation state is used to control (and adjust if desired) one or more of:
- the amount of shear in step (f); and - the residence time of the flocculant-enriched tailings stream in the shear device in step (f). This advantageously allows for a feedback loop to the shear device. In this respect it is noted, that the present invention - apart from introducing the concept of the 'flocculation state' of flocculated tailings as mentioned above - also introduces the concept of using the flocculation state for controlling the flocculation process. By measuring the flocculation state of the flocculated tailings it can be determined whether the flocculation has been effective and, if not, e.g. the amount of shear applied in step (f) can be controlled by increasing or decreasing the amount of shear, if appropriate.
If desired, the flocculated tailings obtained in step (f) may be transported in a pipeline to a remote
- 11 -separator before it is separated in step (g), although it is noted in this respect that the separation already happens in the pipeline (and/or in the deposit areas where the water is collected). Hence, the use of a dedicated separation vessel is possible but not essential to the invention.
In step (g), the flocculated tailings are separated thereby obtaining a dewatered tailings stream and a water-enriched stream. Typically, the dewatered tailings stream comprises from 30 to 75 wt.% solids, preferably above 45 wt.% (and usually below 65 wt.%).
Hereinafter the present invention will be further illustrated by the following non-limiting drawings.
Herein shows:
Fig. 1 schematically a flow scheme of the method for monitoring and controlling the dewatering of an oil sands tailings stream according to the present invention.
For the purpose of this description, same reference numbers refer to same or similar components.
The flow scheme of Figure 1, generally referred to with reference number 1, shows a densitometer 2, a non-contacting NIR device 3 and a flowmeter 4 (respectively for measuring the solids concentration, the clay content and the flow rate of the oil sands tailing stream 10), a shear device 6 (in the embodiment of Figure 1 in the form of a dynamic mixer), a viscometer 5 and flow meter 11 (respectively for measuring the flocculant concentration and the flow rate of the flocculant-containing stream 20), a first PVM 7, a FBRM 8 and a second PVM 9.
During use, the tailings stream is supplied via line 10. After optional diluting with water using water stream 40, at least the solids concentration (in densitometer 2), the clay content (in NIR device 3) and the flow rate . .
In step (g), the flocculated tailings are separated thereby obtaining a dewatered tailings stream and a water-enriched stream. Typically, the dewatered tailings stream comprises from 30 to 75 wt.% solids, preferably above 45 wt.% (and usually below 65 wt.%).
Hereinafter the present invention will be further illustrated by the following non-limiting drawings.
Herein shows:
Fig. 1 schematically a flow scheme of the method for monitoring and controlling the dewatering of an oil sands tailings stream according to the present invention.
For the purpose of this description, same reference numbers refer to same or similar components.
The flow scheme of Figure 1, generally referred to with reference number 1, shows a densitometer 2, a non-contacting NIR device 3 and a flowmeter 4 (respectively for measuring the solids concentration, the clay content and the flow rate of the oil sands tailing stream 10), a shear device 6 (in the embodiment of Figure 1 in the form of a dynamic mixer), a viscometer 5 and flow meter 11 (respectively for measuring the flocculant concentration and the flow rate of the flocculant-containing stream 20), a first PVM 7, a FBRM 8 and a second PVM 9.
During use, the tailings stream is supplied via line 10. After optional diluting with water using water stream 40, at least the solids concentration (in densitometer 2), the clay content (in NIR device 3) and the flow rate . .
- 12 -(in flow meter 4) of the tailings stream 10 are measured.
If desired, optional chemicals (such as coagulants, e.g.
gypsum and alums) may be added as stream 50.
A flocculant-containing stream is supplied via line 20. The concentration (in viscometer 5) of flocculant and the flow rate (in flow meter 11) of the flocculant-containing stream 20 are measured.
Then the flocculant-containing stream 20 is combined with the tailings stream 10 thereby obtaining a flocculant-enriched tailings stream. In the embodiment of Figure 1, the streams 10 and 20 are combined in the dynamic mixer 6. In the dynamic mixer 6, the flocculant-enriched tailings is subjected to shear and mixing thereby obtaining flocculated tailings 30. Subsequently (not shown) the flocculated tailings are separated thereby obtaining a dewatered tailings stream and a water-enriched stream.
The amount of flocculant-containing stream 20 combined in the dynamic mixer 6 is based on the clay content (measured in NIR device 3) of the tailings stream 10 and the concentration (measured in viscometer 5) of flocculant of the flocculant-containing stream 20.
Further, the amount of shear in the dynamic mixer 6 is selected dependent on the solids concentration (measured in densitometer 2), the clay content (measured in NIR device 3), the flow rate (measure in flow meter 4) of the tailings stream 10 and the geometry of the dynamic mixer 6. If desired, the amount of shear can be adjusted by e.g. changing the mixing speed in dynamic mixer 6.
In the embodiment of Fig. 1 a 'flocculation state observer model' was developed to produce an estimate of the flocculation state of the flocculated tailings 30, considering input from the first PVM 7 (on dewaterability
If desired, optional chemicals (such as coagulants, e.g.
gypsum and alums) may be added as stream 50.
A flocculant-containing stream is supplied via line 20. The concentration (in viscometer 5) of flocculant and the flow rate (in flow meter 11) of the flocculant-containing stream 20 are measured.
Then the flocculant-containing stream 20 is combined with the tailings stream 10 thereby obtaining a flocculant-enriched tailings stream. In the embodiment of Figure 1, the streams 10 and 20 are combined in the dynamic mixer 6. In the dynamic mixer 6, the flocculant-enriched tailings is subjected to shear and mixing thereby obtaining flocculated tailings 30. Subsequently (not shown) the flocculated tailings are separated thereby obtaining a dewatered tailings stream and a water-enriched stream.
The amount of flocculant-containing stream 20 combined in the dynamic mixer 6 is based on the clay content (measured in NIR device 3) of the tailings stream 10 and the concentration (measured in viscometer 5) of flocculant of the flocculant-containing stream 20.
Further, the amount of shear in the dynamic mixer 6 is selected dependent on the solids concentration (measured in densitometer 2), the clay content (measured in NIR device 3), the flow rate (measure in flow meter 4) of the tailings stream 10 and the geometry of the dynamic mixer 6. If desired, the amount of shear can be adjusted by e.g. changing the mixing speed in dynamic mixer 6.
In the embodiment of Fig. 1 a 'flocculation state observer model' was developed to produce an estimate of the flocculation state of the flocculated tailings 30, considering input from the first PVM 7 (on dewaterability
- 13 -and yield strength) and optionally normalized to the signal produced by the second PVM 9 (providing a baseline image of the tailing stream 10), the SD/mean of the FBRM
signal obtained in FBRM 8 (on the size of flocs), the clay content (as measured in NIR device 3) and the solids concentration (as measured in densitometer 2). This flocculation state was then used as a control parameter for controlling the amount of shear applied in the dynamic mixer 6. This control parameter could also be used to control the residence time of the flocculant-enriched tailings stream in the dynamic mixer 6.
The person skilled in the art will readily understand that many modifications may be made without departing from the scope of the invention. Further, the person skilled in the art will readily understand that, while the present invention in some instances may have been illustrated making reference to a specific combination of features and measures, many of those features and measures are functionally independent from other features and measures given in the respective embodiment(s) such that they can be equally or similarly applied independently in other embodiments.
signal obtained in FBRM 8 (on the size of flocs), the clay content (as measured in NIR device 3) and the solids concentration (as measured in densitometer 2). This flocculation state was then used as a control parameter for controlling the amount of shear applied in the dynamic mixer 6. This control parameter could also be used to control the residence time of the flocculant-enriched tailings stream in the dynamic mixer 6.
The person skilled in the art will readily understand that many modifications may be made without departing from the scope of the invention. Further, the person skilled in the art will readily understand that, while the present invention in some instances may have been illustrated making reference to a specific combination of features and measures, many of those features and measures are functionally independent from other features and measures given in the respective embodiment(s) such that they can be equally or similarly applied independently in other embodiments.
Claims (59)
1. A method of dewatering of an oil sands tailings stream (10) at least comprising the steps of:
(a) providing a tailings stream (10);
(b) measuring, in-line, one or more of solids concentration (2), clay content (3) and flow rate (4) of the tailings stream (10) provided in step (a);
(c) providing a flocculant-containing stream (20);
(d) measuring a concentration (5) of flocculant of the flocculant-containing stream (20) as provided in step ( c) ;
(e) combining the flocculant-containing stream (20) provided in step (c) with the tailings stream (10) provided in step (a) thereby obtaining a flocculant-enriched tailings stream;
(f) subjecting the flocculant-enriched tailings stream obtained in step (e) to shear, based initially upon the clay content (3), the solids concentration (2) or both, and the tailings flow rate and mixing in a dynamic shear device (6) thereby obtaining flocculated tailings (30);
(g) capturing first images of the flocculated tailings (3) continuously inline and in real time using a first image capturing device (7), or chord-lengths of the flocculated tailings (3) continuously and in-line in real time using a Focused Beam Reflectance Measurement device (FBRM) (8), or both; and (h) separating the flocculated tailings thereby obtaining a dewatered tailings stream and a water-enriched stream;
wherein the amount of flocculant-containing stream (20) combined in step (e) is controlled in real time based on at least the clay content (3), the solids concentration (2) or both, and the tailings flow rate of the tailings stream (10) as measured in step (b) and the concentration (5) of flocculant of the flocculant-containing stream (20) as measured in step (d); and wherein first signals indicative of a flocculation state of the in-line flocculated tailings are derived using the first images of the flocculated tailings (3) inline in real time, or the chord-lengths of the flocculated tailings (3) in-line in real time, or both, for automatically controlling, in real time, adjustment of the initial shear applied in step (f) for controlling the dewaterability and yield strength of the flocculated tailings prior to step (h).
(a) providing a tailings stream (10);
(b) measuring, in-line, one or more of solids concentration (2), clay content (3) and flow rate (4) of the tailings stream (10) provided in step (a);
(c) providing a flocculant-containing stream (20);
(d) measuring a concentration (5) of flocculant of the flocculant-containing stream (20) as provided in step ( c) ;
(e) combining the flocculant-containing stream (20) provided in step (c) with the tailings stream (10) provided in step (a) thereby obtaining a flocculant-enriched tailings stream;
(f) subjecting the flocculant-enriched tailings stream obtained in step (e) to shear, based initially upon the clay content (3), the solids concentration (2) or both, and the tailings flow rate and mixing in a dynamic shear device (6) thereby obtaining flocculated tailings (30);
(g) capturing first images of the flocculated tailings (3) continuously inline and in real time using a first image capturing device (7), or chord-lengths of the flocculated tailings (3) continuously and in-line in real time using a Focused Beam Reflectance Measurement device (FBRM) (8), or both; and (h) separating the flocculated tailings thereby obtaining a dewatered tailings stream and a water-enriched stream;
wherein the amount of flocculant-containing stream (20) combined in step (e) is controlled in real time based on at least the clay content (3), the solids concentration (2) or both, and the tailings flow rate of the tailings stream (10) as measured in step (b) and the concentration (5) of flocculant of the flocculant-containing stream (20) as measured in step (d); and wherein first signals indicative of a flocculation state of the in-line flocculated tailings are derived using the first images of the flocculated tailings (3) inline in real time, or the chord-lengths of the flocculated tailings (3) in-line in real time, or both, for automatically controlling, in real time, adjustment of the initial shear applied in step (f) for controlling the dewaterability and yield strength of the flocculated tailings prior to step (h).
2. The method according to claim 1 further comprising, following step (e), the step of:
capturing second images of the in-line flocculant-enriched tailings stream, continuously and in real time using a second image capturing device (9) prior to the dynamic shear device (6);
deriving second signals from the second images; and comparing the second signals to the first signals for further adjusting the shear applied in step (f).
capturing second images of the in-line flocculant-enriched tailings stream, continuously and in real time using a second image capturing device (9) prior to the dynamic shear device (6);
deriving second signals from the second images; and comparing the second signals to the first signals for further adjusting the shear applied in step (f).
3. The method according to claim 1 wherein the first signals indicative of the flocculation state are derived using image analysis.
4. The method of claim 3 wherein the image analysis comprises one or more of Eigenfunction, Fourier transformation, fractal dimensional analysis, classifiers, wavelet transformation, mean gradient analysis, entropy analysis, spectral weight analysis and combinations thereof.
5. The method according to claim 2 wherein the deriving the second series of signals further comprises using the measurements obtained in step (b).
6. The method according to any one of claims 1 to 5, wherein the tailings stream (10) as provided in step (a) comprises from 55 to 85 wt.% water.
7. The method according to any one of claims 1 to 5, wherein the tailings stream (10) as provided in step (a) comprises from at least 60 wt.% water.
8. The method according to any one of claims 1 to 5, wherein the tailings stream (10) as provided in step (a) comprises at least 65 wt.% water.
9. The method according to any one of claims 1 to 5, wherein the tailings stream (10) as provided in step (a) comprises at most 75 wt.% water.
10. The method according to any one of claims 1 to 5, wherein the tailings stream (10) as provided in step (a) comprises at most 70 wt.% water.
11. The method according to any one of claims 1 to 10, wherein the tailings stream (10) as provided in step (a) comprises from 15 to 45 wt.%
solids,
solids,
12. The method according to any one of claims 1 to 10, wherein the tailings stream (10) as provided in step (a) comprises at least 25 wt.%
solids.
solids.
13. The method according to any one of claims 1 to 10, wherein the tailings stream (10) as provided in step (a) comprises at most 35 wt.% solids
14. The method according to any one of claims 1 to 13 wherein the measuring solids concentration comprises measuring density for determining solids concentration.
15. The method according to any one of claims 1 to 14 further comprising diluting the tailings stream with water for controlling the solids concentration.
16. The method according to any one of claims 1 to 15, wherein in step (b) the clay content (3) is measured using Near-infrared spectroscopy (NIR; 700-2500 nm).
17. The method of claim 16 wherein the measuring of the Near-infrared spectroscopy (NIR; 700-2500 nm) uses a non-contacting NIR device.
18. The method according to any one of claims 1 to 17, wherein the flocculant comprises a polymeric flocculant.
19. The method according to any one of claims 1 to 18 wherein the measuring the concentration (5) of the flocculant comprises measuring viscosity in-line in real time for determining the concentration of the flocculant.
20. The method according to any one of claims 1 to 19, wherein the first image capturing device (7) is a real-time PVM® (Particle Vision Microscope).
21. The method according to claim 2, wherein the second image capturing device (9) is a real-time PVM® (Particle Vision Microscope).
22. The method according to any one of claims 1 to 21, wherein the automatically controlling in real time, the shear applied in step (f) comprises one or more of automatically controlling the amount of shear applied, the residence time of the flocculant-enriched tailings stream in the shear device or combinations thereof.
23. A method of dewatering of an oil sands tailings stream (10) at least comprising the steps of:
(a) providing a tailings stream (10);
(b) measuring, in-line, one or more of solids concentration (2), clay content (3) and flow rate (4) of the tailings stream (10) provided in step (a);
(c) providing a flocculant-containing stream (20);
(d) measuring a concentration (5) of flocculant of the flocculant-containing stream (20) as provided in step ( c) ;
(e) combining the flocculant-containing stream (20) provided in step (c) with the tailings stream (10) provided in step (a) thereby obtaining a flocculant-enriched tailings stream;
(0 subjecting the flocculant-enriched tailings stream obtained in step (e) to shear and mixing in a dynamic shear device (6) thereby obtaining flocculated tailings (30);
(g) capturing first images of the flocculated tailings (3) continuously inline and in real time using a first image capturing device (7), or chord-lengths of the flocculated tailings (3) continuously and in-line in real time using a Focused Beam Reflectance Measurement device (FBRM) (8), or both; and (h) separating the flocculated tailings thereby obtaining a dewatered tailings stream and a water-enriched stream;
wherein the amount of flocculant-containing stream (20) combined in step (e) is controlled in real time based on at least the clay content (3), the solids concentration (2) or both, and the flow rate of the tailings stream (10) as measured in step (b) and the concentration (5) of flocculant of the flocculant-containing stream (20) as measured in step (d); and wherein first signals indicative of a flocculation state of the in-line flocculated tailings are derived using the first images of the flocculated tailings (3) inline in real time, or the chord-lengths of the flocculated tailings (3) in-line in real time, or both, for automatically controlling, in real time, adjustment of the initial shear applied in step (f) for controlling the dewaterability and yield strength of the flocculated tailings prior to step (h).
(a) providing a tailings stream (10);
(b) measuring, in-line, one or more of solids concentration (2), clay content (3) and flow rate (4) of the tailings stream (10) provided in step (a);
(c) providing a flocculant-containing stream (20);
(d) measuring a concentration (5) of flocculant of the flocculant-containing stream (20) as provided in step ( c) ;
(e) combining the flocculant-containing stream (20) provided in step (c) with the tailings stream (10) provided in step (a) thereby obtaining a flocculant-enriched tailings stream;
(0 subjecting the flocculant-enriched tailings stream obtained in step (e) to shear and mixing in a dynamic shear device (6) thereby obtaining flocculated tailings (30);
(g) capturing first images of the flocculated tailings (3) continuously inline and in real time using a first image capturing device (7), or chord-lengths of the flocculated tailings (3) continuously and in-line in real time using a Focused Beam Reflectance Measurement device (FBRM) (8), or both; and (h) separating the flocculated tailings thereby obtaining a dewatered tailings stream and a water-enriched stream;
wherein the amount of flocculant-containing stream (20) combined in step (e) is controlled in real time based on at least the clay content (3), the solids concentration (2) or both, and the flow rate of the tailings stream (10) as measured in step (b) and the concentration (5) of flocculant of the flocculant-containing stream (20) as measured in step (d); and wherein first signals indicative of a flocculation state of the in-line flocculated tailings are derived using the first images of the flocculated tailings (3) inline in real time, or the chord-lengths of the flocculated tailings (3) in-line in real time, or both, for automatically controlling, in real time, adjustment of the initial shear applied in step (f) for controlling the dewaterability and yield strength of the flocculated tailings prior to step (h).
24. The method according to claim 23 further comprising, following step (e), the step of:
capturing second images of the in-line flocculant-enriched tailings stream, continuously and in real time using a second image capturing device (9) prior to the dynamic shear device (6);
deriving second signals from the second images; and comparing the second signals to the first signals for further adjusting the shear applied in step (f).
capturing second images of the in-line flocculant-enriched tailings stream, continuously and in real time using a second image capturing device (9) prior to the dynamic shear device (6);
deriving second signals from the second images; and comparing the second signals to the first signals for further adjusting the shear applied in step (f).
25. The method according to claim 23 wherein the first signals indicative of the flocculation state are derived using image analysis.
26. The method of claim 25 wherein the image analysis comprises one or more of Eigenfunction, Fourier transformation, fractal dimensional analysis, classifiers, wavelet transformation, mean gradient analysis, entropy analysis, spectral weight analysis and combinations thereof.
27. The method according to claim 24 wherein the deriving the second series of signals further comprises using the measurements obtained in step (b).
28. The method according to claim 24, wherein the automatically controlling in real time, the shear applied in step (f) comprises one or more of automatically controlling the amount of shear applied, the residence time of the flocculant-enriched tailings stream in the shear device or combinations thereof.
29. The method according to any one of claims 23 to 28 wherein the tailings stream (10) as provided in step (a) comprises from 55 to 85 wt.%
water.
water.
30. The method according to any one of claims 23 to 28, wherein the tailings stream (10) as provided in step (a) comprises from at least 60 wt.%
water.
water.
31. The method according to any one of claims 23 to 28, wherein the tailings stream (10) as provided in step (a) comprises at least 65 wt.% water.
32. The method according to any one of claims 23 to 28, wherein the tailings stream (10) as provided in step (a) comprises at most 75 wt.% water.
33. The method according to any one of claims 23 to 28, wherein the tailings stream (10) as provided in step (a) comprises at most 70 wt.% water.
34. The method according to any one of claims 23 to 33, wherein the tailings stream (10) as provided in step (a) comprises from 15 to 45 wt.%
solids,
solids,
35. The method according to any one of claims 23 to 33, wherein the tailings stream (10) as provided in step (a) comprises at least 25 wt.%
solids.
solids.
36. The method according to any one of claims 23 to 33, wherein the tailings stream (10) as provided in step (a) comprises at most 35 wt.% solids
37. The method according to any one of claims 23 to 36 wherein the measuring solids concentration comprises measuring density for determining solids concentration.
38. The method according to any one of claims 23 to 37 further comprising diluting the tailings stream with water for controlling the solids concentration.
39. The method according to any one of claims 23 to 38, wherein in step (b) the clay content (3) is measured using Near-infrared spectroscopy (NIR;
700-2500 nm).
700-2500 nm).
40. The method of claim 39 wherein the measuring of the Near-infrared spectroscopy (NIR; 700-2500 nm) uses a non-contacting NIR device.
41. The method according to any one of claims 23 to 40, wherein the flocculant comprises a polymeric flocculant.
42. The method according to any one of claims 23 to 41 wherein the measuring the concentration (5) of the flocculant comprises measuring viscosity in-line in real time for determining the concentration of the flocculant.
43. The method according to any one of claims 23 to 42, wherein the first image capturing device (7) is a real-time PVM® (Particle Vision Microscope).
44. The method according to claim 24, wherein the second image capturing device (9) is a real-time PVM® (Particle Vision Microscope).
45. A method of dewatering of an oil sands tailings stream (10) at least comprising the steps of:
(a) providing a tailings stream (10);
(b) measuring, in-line, one or more of solids concentration (2), clay content (3) and flow rate (4) of the tailings stream (10) provided in step (a);
(c) providing a flocculant-containing stream (20);
(d) measuring a concentration (5) of flocculant of the flocculant-containing stream (20) as provided in step ( c) ;
(e) combining the flocculant-containing stream (20) provided in step (c) with the tailings stream (10) provided in step (a) thereby obtaining a flocculant-enriched tailings stream;
(f) subjecting the flocculant-enriched tailings stream obtained in step (e) to shear, based initially upon the clay content (3), the solids concentration (2) or both, and the flow rate of the tailings and mixing in a dynamic shear device (6) thereby obtaining flocculated tailings (30); and (h) separating the flocculated tailings thereby obtaining a dewatered tailings stream and a water-enriched stream;
wherein the amount of flocculant-containing stream (20) combined in step (e) is controlled in real time based on at least the clay content (3), the solids concentration (2) or both, and the flow rate of the tailings stream (10) as measured in step (b) and the concentration (5) of flocculant of the flocculant-containing stream (20) as measured in step (d).
(a) providing a tailings stream (10);
(b) measuring, in-line, one or more of solids concentration (2), clay content (3) and flow rate (4) of the tailings stream (10) provided in step (a);
(c) providing a flocculant-containing stream (20);
(d) measuring a concentration (5) of flocculant of the flocculant-containing stream (20) as provided in step ( c) ;
(e) combining the flocculant-containing stream (20) provided in step (c) with the tailings stream (10) provided in step (a) thereby obtaining a flocculant-enriched tailings stream;
(f) subjecting the flocculant-enriched tailings stream obtained in step (e) to shear, based initially upon the clay content (3), the solids concentration (2) or both, and the flow rate of the tailings and mixing in a dynamic shear device (6) thereby obtaining flocculated tailings (30); and (h) separating the flocculated tailings thereby obtaining a dewatered tailings stream and a water-enriched stream;
wherein the amount of flocculant-containing stream (20) combined in step (e) is controlled in real time based on at least the clay content (3), the solids concentration (2) or both, and the flow rate of the tailings stream (10) as measured in step (b) and the concentration (5) of flocculant of the flocculant-containing stream (20) as measured in step (d).
46. The method according to claim 45, wherein the tailings stream (10) as provided in step (a) comprises from 55 to 85 wt.% water.
47. The method according to claim 45 wherein the tailings stream (10) as provided in step (a) comprises from at least 60 wt.% water.
48. The method according to claim 45, wherein the tailings stream (10) as provided in step (a) comprises at least 65 wt.% water.
49. The method according to claim 45, wherein the tailings stream (10) as provided in step (a) comprises at most 75 wt.% water.
50. The method according to claim 45, wherein the tailings stream (10) as provided in step (a) comprises at most 70 wt.% water.
51. The method according to any one of claims 45 to 50, wherein the tailings stream (10) as provided in step (a) comprises from 15 to 45 wt.%
solids,
solids,
52. The method according to any one of claims 45 to 50, wherein the tailings stream (10) as provided in step (a) comprises at least 25 wt.%
solids.
solids.
53. The method according to any one of claims 45 to 50, wherein the tailings stream (10) as provided in step (a) comprises at most 35 wt.% solids
54 The method according to any one of claims 45 to 53 wherein the measuring solids concentration comprises measuring density for determining solids concentration.
55. The method according to any one of claims 45 to 54 further comprising diluting the tailings stream with water for controlling the solids concentration.
56. The method according to any one of claims 45 to 55, wherein in step (b) the clay content (3) is measured using Near-infrared spectroscopy (NIR;
700-2500 nm).
700-2500 nm).
57. The method of claim 56 wherein the measuring of the Near-infrared spectroscopy (NIR; 700-2500 nm) uses a non-contacting NIR device.
58. The method according to any one of claims 45 to 57, wherein the flocculant comprises a polymeric flocculant.
59. The method according to any one of claims 45 to 58 wherein the measuring the concentration (5) of the flocculant comprises measuring viscosity in-line in real time for determining the concentration of the flocculant.
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| CA2937452A CA2937452C (en) | 2016-07-28 | 2016-07-28 | Method of dewatering of a tailings stream |
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| Application Number | Priority Date | Filing Date | Title |
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| CA2937452A CA2937452C (en) | 2016-07-28 | 2016-07-28 | Method of dewatering of a tailings stream |
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| CA2937452C true CA2937452C (en) | 2020-12-15 |
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