CA3037959C

CA3037959C - Pretreatment of froth treatment affected tailings with floatation and stripping prior to tailings dewatering and containment

Info

Publication number: CA3037959C
Application number: CA3037959A
Authority: CA
Inventors: Elco Dick Hollander; Babak Derakhshandeh; Wayne Brown; Javed Ally; Cedric LABORDE-BOUTET
Original assignee: Suncor Energy Inc
Current assignee: Suncor Energy Inc
Priority date: 2019-03-26
Filing date: 2019-03-26
Publication date: 2023-01-17
Anticipated expiration: 2039-03-26
Also published as: CA3037959A1

Abstract

A two-stage process for pre-treating froth treatment affected tailings obtain from a tailings pond includes a floatation stage and a stripping stage. The floatation stage can be the first stage for removing bitumen and dissolved light hydrocarbons, such as naphthenic diluent, while the stripping stage then removes residual light hydrocarbons to produce a vapour stream including air and light hydrocarbons as well as a cleaned tailings stream. The cleaned tailings is then be subjected to dewatering, which can include the addition of an immobilization chemical and a flocculant followed by pipelining and discharging into a mine pit to form a permanent aquatic storage structure with a settle solids-rich layer and a water cap.

Description

PRETREATMENT OF FROTH TREATMENT AFFECTED TAILINGS WITH
FLOATATION AND STRIPPING PRIOR TO TAILINGS DEWATERING AND
CONTAINMENT
TECHNICAL FIELD
[001] The technical field generally relates to the treatment of tailings, and more particularly the pre-treatment of froth treatment affected tailings prior to subjecting the tailings to flocculation and dewatering.
BACKGROUND

[002] There are several techniques that have been developed for treating fine tailings in order to separate the particulate mineral solids from the water. Some techniques involve the addition of an immobilization chemical and a flocculant into the fine tailings followed by deposition of the flocculated tailings into a containment area to form a layer of settled solids layer that is capped by a water layer.

[003] Various types of tailings materials are produced in mining and extraction operations. For example, in oil sands extraction operations, several streams of coarse and fine tailings are produced and typically supplied to tailings ponds for storage. One type of tailings stream that is produced by bitumen froth treatment contains light hydrocarbons, such as diluent or solvent, that are part of the froth treatment process. In bitumen froth treatment, a diluent or solvent is added to the bitumen froth in order to enhance the separation of the bitumen components from the aqueous and mineral solids components of the bitumen froth. Some of the diluent or solvent reports to the underflow tailings streams in the froth treatment process and residual amounts can thus be present in tailings ponds.

[004] There are indeed a number of challenges in the area of tailings management, handling, treatment and disposal.
SUMMARY

[005] A two-stage process for removing light hydrocarbons, such as naphthenic diluent, froth treatment affected tailings using both floatation and stripping can facilitate the removal of the bitumen and light hydrocarbons to produce cleaned tailings for treatment in a dewatering operation as well as generating suitable output streams, such as bitumen froth and a light hydrocarbon vapour. Floatation particularly facilitates efficient removal of a portion of the bitumen, which includes dissolved light hydrocarbons, while stripping enables a polishing of the tailings to further reduce the light hydrocarbon content to desired levels for the dewatering operation. The two-stage process can facilitate generating a bitumen froth material that is of adequate quality while producing a cleaned tailings material that has a desired low light hydrocarbon content for dewatering operations that may form, for example, a permanent aquatic storage structure (PASS) with settled solid material and a water cap.

[006] In some implementations, there is provided a process for treating froth treatment tailing (FTT) affected tailings that includes bitumen and naphthenic diluent, comprising: retrieving FTT-affected tailings from a tailings pond; diluting the FTT-affected tailings with water to produce diluted tailings; subjecting the diluted tailings to floatation comprising providing air bubbles and agitation in a floatation vessel to produce a bitumen froth overflow stream and a bitumen depleted tailings stream that includes residual diluent that are withdrawn from the floatation vessel; subjecting the bitumen depleted tailings stream to stripping comprising providing air bubbles in a stripper vessel to strip at least a portion of the residual diluent from the bitumen depleted tailings to produce a vapor overhead stream comprising air and diluent and a cleaned tailings stream having a diluent content below a threshold level, that are withdrawn from the stripper vessel; and subjecting the cleaned tailings to dewatering. The dewatering can include adding an immobilization chemical and a flocculant to the cleaned tailings to produce a flocculated tailings material; and supplying the flocculated tailings material into a mine pit to form a PASS that includes a settled solids-rich layer and a water cap.

[007] In some implementations, the FTT-affected tailings comprise mature fine tailings (MFT) retrieved from the tailings pond. The dilution can be performed to reduce a yield stress of the diluted tailings to below 5 Pa, below 3 Pa, or below 1 Pa.
The floatation an include injection of air into the floatation vessel at superficial gas velocities of less than 1 cm/s, less than 0.5 cm/s, less than 0.3 cm/s, less than 0.2 cm/s and can be above 0.1 cm/s or above 0.15 cm/s. The agitation during floatation is performed to provide high-energy mechanical agitation of at least 0.65 W/Kg, at least 1 W/Kg, at least 1.5 W/Kg, at least 5 W/Kg, and/or up to at most 8.3 W/Kg. The stripping can include injection of air into the stripper vessel at superficial gas velocities above 1 cm/s, above 3 cm/s, above 5 cm/s and/or up to 10 cm/s. Agitation can be provided in the stripper vessel during stripping to provide mechanical agitation, which can be above 0.1 W/Kg and below 1 W/Kg, and can be provided to keep mineral solids suspended. The agitation in the stripper vessel is preferably provided at lower mechanical energies compared to the agitation in the floatation vessel, and/or the air in the stripper vessel is provided at higher superficial gas velocities compared to the air in the floatation vessel.

[008] In some implementations, the process includes adding a second tailings stream to the cleaned tailings, the second tailings stream being a non-FTT-affected tailings that does not contain substantial light hydrocarbons. The process can also include subjecting the bitumen froth overflow to froth processing in order to produce at least one bitumen enriched component and at least one water and solid enriched component. The process can also include supplying the bitumen froth overflow into an oil sands extraction facility.

[009] In some implementations, the process includes subjecting the diluent in the vapor overhead stream to destruction, such as by thermal or catalytic combustion in order to produce energy. The process can also include subjecting the vapor overhead stream to diluent recovery. The diluent recovery can include condensation of diluent to produce liquid diluent and diluent depleted air. The liquid diluent can be recylced into a froth treatment operation or another unit of the oil sands extraction operation.

[0010] In some implementations, the FTT-affected tailings have a diluent content above 1000ppm or above 2000ppm upon retrieval from the tailings pond. The floatation and the stripping can be operated so that the diluent content of the cleaned tailings is below 250ppm, 200ppm, 150ppm, 100ppm or 8Oppm or below the threshold so as to be suitable for the dewatering of the cleaned tailings. The floatation can be operated such that between 40% and 80%, or between 50 and 75%, of the diluent in the FTT-affected tailings are removed. The stripping can be operated such that between 50% and 90%, or between 55% and 80%, of the residual diluent in the bitumen depleted tailings is removed. The floatation and stripping can be operated such that at least 90%
of the diluent in the FIT-affected tailings has been removed from the cleaned tailings.

[0011] In some implementations, the floatation is performed using a single floatation vessel or a series of multiple floatation vessels. In some implementations, the stripping is performed using a single stripper vessel or a series of multiple stripper vessels. The floatation vessel or the stripper vessel or both can each have a roof for retaining vapours within a chamber of the vessel. The floatation vessel or the stripper vessel or both can each have a vapour outlet system for collecting and transporting vapours out of the chamber of the vessel.

[0012] In some implementations, there is provided a process for treating froth treatment tailing (FTT) affected tailings that includes bitumen and light hydrocarbons, comprising; subjecting the FTT-affected tailings to floatation comprising providing gas bubbles therein to produce a bitumen froth material that floats upward and a bitumen depleted tailings material that includes light hydrocarbons; subjecting the bitumen depleted tailings material to stripping comprising providing gas bubbles to strip at least a portion of the residual light hydrocarbons from the bitumen depleted tailings to produce an overhead vapour comprising air and light hydrocarbons and a cleaned tailings material; and subjecting the cleaned tailings material to dewatering. The dewatering can include adding a flocculant to the cleaned tailings material to produce a flocculated tailings material; and discharging the flocculated tailings material into a sub-aerial deposition location to allow water to separate from flocculated solid material.

[0013] In some implementations, the floatation or the stripping or both are performed in situ within a tailings pond. The floatation or the stripping or both can employ caisson-type vessels deployed in the tailings pond.

[0014] In some implementations, the floatation or the stripping or both are performed ex situ within a floatation vessel and a stripper vessel respectively.

[0015] In some implementations, the floatation is conducted in situ, the bitumen depleted tailings material is retrieved from the tailings pond and supplied into a stripper vessel, and the stripper vessel is operated to produce an underflow stream of the cleaned tailings material and an overhead stream of the overhead vapour.

[0016] In some implementations, the light hydrocarbons comprise naphthenic or paraffinic solvent or a combination thereof.

[0017] In some implementations, the dewatering further comprises adding an immobilization chemical to the cleaned tailings material. The dewatering can further include discharging the flocculated tailings material into a mine pit as the sub-aerial deposition location to form a PASS that includes a settled solids-rich layer and a water cap. Alternatively, the dewatering can include discharging the flocculated tailings material in thin lifts onto a sloped deposition area as the sub-aerial deposition location to allow water to drain away from drying solid material.

[0018] In some implementations, the gas provided in the floatation or the stripping or both is air.

[0019] In some implementations, the FTT-affected tailings is diluted to obtain a yield strength below a certain value, such as below 5 Pa or 1 Pa, for example. The dilution can be performed using process water.

[0020] In some implementations, there is provided a process for treating froth treatment tailing (FTT) affected tailings that includes bitumen and light hydrocarbons, comprising: subjecting the FTT-affected tailings to stripping comprising providing gas bubbles to strip at least a portion of the residual light hydrocarbons from the tailings to produce an overhead vapour comprising air and light hydrocarbons and a stripped tailings material that includes residual bitumen; subjecting the stripped tailings material to floatation comprising providing gas bubbles therein to produce a bitumen froth material that floats upward and a cleaned tailings material; and subjecting the cleaned tailings material to dewatering. The dewatering can include adding a flocculant to the cleaned tailings material to produce a flocculated tailings material; and discharging the flocculated tailings material into a sub-aerial deposition location to allow water to separate from flocculated solid material.

[0021] As mentioned above and herein, the process can have various features regarding the operation of the stripping and floatation stages, for example regarding dilution, agitation, air injection, in situ or ex situ operation, unit design and arrangements, froth and vapour overhead processing, features of the dewatering stage, and so on.

[0022] In some implementation, there is provided a system for treating froth treatment tailing (FTT) affected tailings that includes bitumen and light hydrocarbons, comprising: a retrieval assembly comprising a pipeline and a pump for retrieving FTT-affected tailings from a tailings source; a floatation unit comprising at least one floatation vessel in fluid communication with the retrieval assembly to receive the FTT-affected tailings, the floatation vessel comprising an air injection system for providing air bubbles, an agitation system for agitating the FIT-affected tailings, a froth outlet to withdraw a bitumen froth overflow stream and a tailings outlet to withdraw a bitumen depleted tailings stream that includes residual light hydrocarbons that are withdrawn from the floatation vessel; a stripping unit comprising at least one stripper vessel to strip at least a portion of the residual light hydrocarbons from the bitumen depleted tailings, the stripper vessel having a tailings inlet in fluid communication with the tailings outlet of the floatation vessel, an air injection system for providing air bubbles, an upper outlet for releasing a vapor overhead comprising air and stripped light hydrocarbons and a tailings outlet for withdrawing a cleaned tailings stream; and a dewatering unit. The dewatering unit can include a chemical addition assembly in fluid communication with the tailings outlet for receiving the cleaned tailings stream and adding an immobilization chemical and a flocculant thereto to produce a flocculated tailings material; a pipeline coupled to the chemical addition assembly and configured to supply the flocculated tailings material into a mine pit to form a PASS that includes a settled solids-rich layer and a water cap.

[0023] In some implementations, the tailings source is a tailings pond. The retrieval assembly can include a dredge or a barge. The retrieval assembly can be configured to access mature fine tailings (MFT) or fluid tailings from a tailings pond to obtain the FTT-affected tailings.

[0024] In some implementations, the air injection system of the floatation unit comprises a sparger, and the agitation system of the floatation unit comprises an impeller. The air injection system of the stripping unit can also include a sparger. The stripping unit can include an agitation system that also includes an impeller.
The impellers are driven by corresponding motors.

[0025] In some implementations, the system also includes a dilution assembly configured to add a dilution liquid into the FTT-affected tailings prior to the floatation unit.
The dilution assembly can be configured to dilute the FIT-affected tailings to have a reduced yield strength below 5 Pa or below 1 Pa, for example.

[0026] In some implementations, the air injection systems of the floatation unit can be configured to provide superficial gas velocities within certain ranges as described herein, and the agitation system of the floatation unit can be configured to provide mechanical agitation at certain ranges as described herein. The air injection system and an agitation system of the stripping unit can also be configured for operation within certain ranges.

[0027] In some implementations, the system also includes an addition line configured to add a second tailings stream to the cleaned tailings, the second tailings stream being a non-FIT-affected tailings that does not contain substantial light hydrocarbons.

[0028] In some implementations, the system includes a froth reprocessing assembly configured for subjecting the bitumen froth overflow to froth processing in order to produce at least one bitumen enriched component and at least one water and solid enriched component.

[0029] In some implementations, the system also includes a vapour overhead treatment assembly configured for processing at least a portion of the vapour overhead.
The vapour overhead treatment assembly can include a combustion system to enable thermal or catalytic combustion of light hydrocarbons in the vapour overhead.
The vapour overhead treatment assembly can incldue a light hydrocarbon recovery system.
The light hydrocarbon recovery system can include a condenser to condense light hydrocarbons to produce recovered liquid and light hydrocarbon depleted air.

[0030] In some implementations, the floatation and stripping units are configured to be operated so that the light hydrocarbon content of the cleaned tailings is brought below certain thresholds or enables certain recovery levels at the different stages, such that the cleaned tailings are suitable for the dewatering of the cleaned tailings.

[0031] The floatation and stripping units can each include a single vessel or a series of multiple vessels. The vessels can each have a roof for retaining vapours within a chamber of the vessel and/or a vapour outlet system for collecting and transporting vapours out of the chamber of the vessel.

[0032] The light hydrocarbons can incldue naphthenic diluent or paraffinic solvent (e.g., C5 to C7 alkanes) or other hydrocarbons within the Fl fraction.

[0033] In some implementations, there is provided a system for treating froth treatment tailing (FTT) affected tailings that includes bitumen and light hydrocarbons, comprising: a retrieval assembly comprising a pipeline and a pump for retrieving FTT-affected tailings from a tailings source; a stripping unit comprising at least one stripper vessel comprising a tailings inlet in fluid communication with the retrieval assembly to receive the FTT-affected tailings, an air injection system for providing air bubbles to strip a portion of the light hydrocarbons from the FTT-affected tailings, an upper outlet for releasing a vapor overhead comprising air and stripped light hydrocarbons and a tailings outlet for withdrawing a light hydrocarbon depleted tailings stream that includes residual bitumen; a floatation unit comprising at least one floatation vessel comprising a tailings inlet in fluid communication with the tailings outlet of the stripping vessel to receive the light hydrocarbon depleted tailings stream, an air injection system for providing air bubbles to generate a bitumen froth, an agitation system for agitating the light hydrocarbon depleted tailings stream, a froth outlet to withdraw a bitumen froth overflow stream and a tailings outlet to withdraw a cleaned tailings stream; and a dewatering unit. The dewatering unit can include a chemical addition assembly in fluid communication with the tailings outlet for receiving the cleaned tailings stream and adding an immobilization chemical and a flocculant thereto to produce a flocculated tailings material; and a pipeline coupled to the chemical addition assembly and configured to supply the flocculated tailings material into a mine pit to form a PASS that includes a settled solids-rich layer and a water cap.

[0034] The system with the stripping unit followed by a floatation unit can have various additional features as described above or herein.

[0035] In some implementations, there is provided a process for treating froth treatment tailing (FTT) affected tailings that includes bitumen and light hydrocarbons, comprising:
subjecting the FTT-affected tailings to a multi-stage air bubbling process to produce at least one bitumen froth stream comprising bitumen and dissolved light hydrocarbons, vapour overhead comprising light hydrocarbons and air, and a cleaned tailings material that are depleted in light hydorcarbons; and dewatering the cleaned tailings, wherein the dewatering. The dewatering can include adding an immobilization chemical and a flocculant to the cleaned tailings to produce a flocculated tailings material;
and pipelining the flocculated tailings material into a containment earthwork structure to form a PASS
that includes a settled solids-rich layer and a water cap.
[0035a] In accordance with another aspect, there is provided a process for stripping froth treatment tailing (FTT) affected tailings that includes bitumen and light hydrocarbons, comprising: providing gas bubbles to strip the light hydrocarbons from the FTT-affected Date Recue/Date Received 2021-05-21 8a tailings; and producing an overhead vapour comprising air and at least a portion of the light hydrocarbons and a stripped tailings material that includes residual bitumen.
[0035b] In accordance with another aspect, there is provided a system for treating froth treatment tailing (FTT) affected tailings that includes bitumen and light hydrocarbons, the system comprising: a stripping unit comprising at least one stripper vessel comprising: a tailings inlet to receive the FTT-affected tailings; a gas injection system for providing gas bubbles to strip a portion of the light hydrocarbons from the FTT-affected tailings; an upper outlet for releasing a vapour overhead comprising air and stripped light hydrocarbons; and a tailings outlet for withdrawing a cleaned tailings material that are depleted in light hydrocarbons and that include residual bitumen.

[0036] It should be understood that the processes and systems as described above can have further features that are described below or illustrated in the drawings.
Date Recue/Date Received 2021-05-21 BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 is a process flow diagram illustrating an example pretreatment of froth treatment affected tailings prior to dewatering of the tailings.

[0038] Figure 2 is another process flow diagram illustrating another example pretreatment of froth treatment affected tailings prior to dewatering of the tailings.

[0039] Figure 3 is yet another process flow diagram illustrating a further example pretreatment of froth treatment affected tailings prior to dewatering of the tailings.

[0040] Figure 4 is a diagram showing a separation vessel.

[0041] Figure 5 is another diagram showing a different separation vessel.

[0042] Figure 6 is a further diagram showing a separation vessel with a downcomer.

[0043] Figure 7 is another diagram showing part of a separation vessel with a roof.

[0044] Figure 8 is a process flow diagram illustrating yet another example pretreatment of froth treatment affected tailings prior to dewatering of the tailings.

[0045] Figure 9 is a graph of measured rate constant versus N3.29D2.29 J90.73.

[0046] Figure 10 is a graph of stripped naphtha mass versus time, including estimate and model prediction curves.
DETAILED DESCRIPTION

[0047] Techniques to pretreat froth treatment affected tailings include a multi-stage process for removing light hydrocarbons from the tailings to produce a cleaned tailings material that is suitable for treatment in a dewatering process. For example, the process can include subjecting the tailings to floatation to produce a bitumen froth overflow and a bitumen depleted tailings, which are subsequently subjected to stripping to produce a vapor overhead stream that contains diluent or solvent and a bottom cleaned tailings stream that is suitable for treatment in the dewatering process. In some implementations, this two-stage process facilitates removal of diluent from the tailings such that the cleaned tailings can be advantageously flocculated, dewatered and contained.

[0048] The dewatering process can include the addition of an immobilization chemical as well as a flocculant in order to produce a flocculated tailings material that is supplied into a mine pit or other containment structure in order to form a permanent aquatic storage structure (PASS) having a water cap and a bottom settled solids layer that contains and entraps contaminants of concern. By pretreating the diluent affected tailings in order to remove a substantial amount of the diluent prior to the dewatering operation, negative impacts that diluent could have for the long-term sustainability of the dewatered solids can be achieved.

[0049] Residual light hydrocarbons, such as naphtha and paraffinic solvent, are present in froth treatment tailings that are produced during bitumen froth treatment processes. Naphtha is used as diluent in naphthenic froth treatment (NFT), while paraffinic solvent is used in paraffinic froth treatment (PET) processes.
Froth treatment tailings are typically supplied to a tailings pond and therefore the light hydrocarbons can be present in various parts of the tailings pond. Tailings that have been affected by the light hydrocarbons of froth treatment and are found in the tailings pond can be referred to as froth treatment tailings (FTT) affected tailings or froth treatment affected tailings. In general, the tailings material treated using the techniques described herein can be referred to as "FTT-affected tailings". The light hydrocarbons found in such tailings can support microbial activity and could therefore impact or alter aquatic closure performance as well as add to greenhouse gas and volatile organic compound emissions. The light hydrocarbons used in froth treatment can therefore be a challenge in terms of processing tailings from ponds in order to separate water from the mineral solids and move toward reclamation or permanent containment of the materials.

[0050] By removing a substantial portion or all of the light hydrocarbons from the FTT-affected tailings, the resulting cleaned tailings can be flocculated and dewatered more efficiently and effectively. For example, the settled solids layer at the bottom of the PASS
deposit can have minimal microbial activity related to the presence of such light hydrocarbons. Various techniques and systems will be described for the removal of light hydrocarbons, such as diluent, from FTT-affected tailings further below.

[0051] Referring to Figure 1, in one implementation, froth treatment tailings (10) are supplied from an upstream froth treatment operation (not shown) into a tailings pond (12). A tailings stream can be retrieved from the tailings pond (12) and may be from the mature fine tailings (MET) layer of the tailings pond (12). It is noted that the tailings stream can be obtained from various tailings sources that include "fluid tailings". This tailings stream can be referred to as FIT-affected tailings (14), affected MET, "aMFT", or FTT-affected affected fluid tailings, for example. A pump (16) can be used to retrieve the affected MET (14) from the tailings pond (12) and supplied to a two-stage diluent separation system (17). The pump could also be a dredge or a barge. While the FTT-affected tailings (14) that are supplied to the two-stage diluent separation system (17) are typically from an MET layer of a tailings pond, they can also be sourced from other FIT-affected tailings sources and could include or consist of FIT supplied directly from the froth treatment operation. The tailings that are fed into the two-stage diluent separation system (17) can be any combination of FIT, FIT-affected tailings, and other tailings materials that contain or are affected by light hydrocarbons. It is also noted that tailings not affected by light hydrocarbons can be combined with the affected tailings to form the tailings stream fed into the two-stage diluent separation system (17).

[0052] The two-stage diluent separation system (17) can include a floatation unit (18) as the first stage. The floatation unit (18) can include a floatation vessel (20), a mixing system that can include an agitator or mixer (22), an air inlet (24), and as well as overflow and underflow outlets. The floatation stage is operated to produce at least a bitumen froth overflow (26) and a bitumen depleted tailings underflow (28).
Other outlets, such as a middlings outlet, can be provided if desired. The affected tailings stream 14 can be directly pumped into the floatation unit (18), or it can be pre-treated to change one or more properties. For example, as shown in Figure 1, water (29) can be added to the affected MET (14) prior to introduction into the floatation unit (18) or into the floatation vessel (20) itself. This pre-dilution of the affected tailings 14 can be performed depending on the solids content and other properties of the tailings retrieved from the pond (12). For example, if high solids MFT (e.g., around 40 wt% solids) is retrieved from the pond (12), then it can be diluted with water to a solids content of 10 to 30 wt%, or 15 to 20 wt%, prior to introduction into the flotation unit (18). It is also noted the dilution can be performed to reduce the yield strength of the retrieved tailings to below a yield strength threshold, which may be about 5 Pa. Yield strength of the tailings can be lowered by subjecting the tailings to high shearing, dilution, and/or modifying the chemistry related to the clays in the tailings.

[0053] It is also noted that the first and second stages can have corresponding predilution to facilitate providing the rheology for the given separation mechanisms.
Thus, the first stage (e.g., floatation) can have a dilution to facilitate removal of bitumen from tailings by air floatation, while the second stage (e.g., stripping) can have a dilution to facilitate separation of light hydrocarbons to be separated from the tailings (e.g., to ensure bubbles can be dispersed finely enough such that solvent dissolved in the bitumen can transfer from the bitumen phase to the gas phase). For instance, if stripping would benefit from a lower yield stress to facilitate separation, then additional dilution can be provided for the feed material to the stripper.

[0054] In one implementation, the floatation stage can employ relatively low air flow rate as well as relatively high mechanical energy input, e.g., provided by the mechanical agitator (22), in order to induce formation of an upper zone of bitumen froth and a lower zone of bitumen depleted tailings. It has been found that a notable amount (e.g., the majority) of the light hydrocarbons, such as diluent, can be found dissolved within the bitumen of the tailings. Therefore, the bitumen froth overflow will contain light hydrocarbons as well as the heavier components of the bitumen. The floatation stage can also be operated to enable the removal of a given percentage of the light hydrocarbons found in the affected MFT (14). For example, the light hydrocarbon recovery in the floatation stage may be between 50% and 80%, or between 60%
and 70% of the light hydrocarbons originally in the affected MFT, such that a majority but not all of the light hydrocarbons are removed along with bitumen in the floatation stage. In another example, the floatation stage is operated so that the bitumen depleted tailings has a light hydrocarbons content below 500-1000ppm, and then the stripping stage is operated so that the cleaned tailings has a light hydrocarbons content below 250ppm or preferably below 200ppm, 150ppm, 100ppm, or 50ppm, for example.

[0055] Still referring to Figure 1, the bitumen depleted tailings (28) produced by the floatation stage are then sent to the second separation stage, which is a stripping stage that includes a stripper (30). The stripper (30) includes a stripping vessel (32) with a feed inlet for the bitumen depleted tailings as well as an overhead outlet and a bottoms outlet.
The stripper (30) also includes an air inlet (34) for injecting air into the tailings material, as well as a mixing system that can include an agitator or mixer (36). Other inlets and outlets can also be provided, if desired.

[0056] The stripping stage can be operated as a polishing stage in order to remove the smaller amounts of light hydrocarbon that remain within the bitumen depleted tailings (28). The stripping stage produces a vapor overhead stream (38) that includes both air and stripped light hydrocarbons, and a cleaned tailings stream (40) which is substantially depleted in bitumen and light hydrocarbons. The cleaned tailings (40) may include, for example, below 250ppm or below 100ppm of light hydrocarbons, such as diluent.
The cleaned tailings may also have a diluent content that represents at least 90%
recovery compared to the diluent content of the affected MFT (14) and/or at least 50 to 70%
recovery compared to the diluent content of the flotation underflow which is the bitumen depleted tailings stream.

[0057] While an example of the flotation and stripping stages have been described above, it should be noted that there are various other possible implementations of the two-stage pre-treatment process. Some of the possible implementations, including equipment that could be used, will be described further below.

[0058] Still referring to Figure 1, the cleaned tailings (40) can be combined with another tailings stream that has not been affected by FFT. This non-FFT
affected tailings (42) can be withdrawn from a different tailings pond (12a) or could be withdrawn from the same tailings pond as the affected MET but from a different location where FFT
has not affected and therefore light hydrocarbon content is very low or zero. The combining of different tailings streams can be performed in order to obtain a combined tailings material that has a desired composition, notably a desired low level of light hydrocarbons. To this end, the different tailings streams can be subjected to measurements to determine diluent content, and then the tailings stream can be combined in a proportion to obtain an overall desired diluent content. The final combined tailings stream can be provided with a diluent content below 250ppm, 200ppm, 100 ppm, 80 ppm, or 60 ppm, or lower, for example, and this final diluent threshold can be determined depending on the dewatering process to be used.

[0059] As shown in Figure 1, the cleaned tailings (40), which may have been combined with a non-FTT affected tailings material, can then be supplied to a dewatering stage (44). There are various types of dewatering operations that exist that can be used for separating water from the mineral solids contained in the cleaned tailings (40). In one example, the dewatering operation includes adding an immobilization chemical (46) to cleaned tailings (40) followed by a flocculant (48) in order to produce a flocculated tailings material (50), which is then conditioned in a pipeline and supplied to a permanent aquatic storage structure, "PASS" (52). In the PASS, the flocculated solids with immobilized contaminants of concern settle to the bottom to form a settled solids layer (54), and a water cap (56) forms as an upper layer of the PASS. Various details regarding this type of potential dewatering operation can be found described in Canadian patent document Nos. CA 2,958,873 and 2,921,835.

[0060] It is also noted that alternative dewatering processes can also be used. For example, in one dewatering process a flocculent solution can be added to the cleaned tailings in order to produce a flocculated tailings material which can then be pipeline conditioned and deposited in thin lifts on a sloped sub-aerial deposition area in order to form a dry tailings material and allowing the water to drain and flow away from the drying solids. Various other dewatering processes can also be used and can involve filters, thickeners, deposition methods, and various other techniques.

[0061] Still referring to Figure 1, while the main material of concern is the FTT-affected tailings (14) which is pretreated in order to remove bitumen and light hydrocarbons so that the cleaned tailings (40) can be subjected to flocculation and dewatering, the upper streams including the bitumen froth overflow (26) and the vapor overhead (38) can also be subjected to further processing. Some example processing of such streams will be described below.

[0062] In one implementation, the bitumen froth overflow (26) can be subjected to froth processing (58) in order to separate one or more of its various components, including bitumen, water, solids, and diluent. The froth processing can include one or more separators that remove water and solids from the bitumen froth overflow (26) in order to produce an upgraded froth that is suitable for reintroduction into the froth treatment process of the main oil sands processing plant. It should be noted that the froth processing (58) can also be adapted depending on the type of light hydrocarbons that are present in the tailings bitumen. For example, when naphthenic diluent is the light hydrocarbon, the bitumen froth overflow (26) should have a manageable consistency where solids and water can be removed and the diluted upgraded froth can then be fed back into froth treatment or primary separation units of the oil sands processing plant.
Date Recue/Date Received 2020-11-06

[0063] In addition, in some implementations, the floatation stage is operated such that the bitumen froth overflow (26) can be directly introduced into the main oil sands processing plant at one or more locations, e.g., into one or more vessel that is part of a primary separation stage that separates oil sands slurry into tailings and bitumen froth and/or part of a secondary separation stage that involves NFT or PFT.

[0064] On the other hand, when paraffinic solvent is the light hydrocarbon, the bitumen froth overflow (26) may contain higher amounts of asphaltenes that were rejected as part of the PFT operation. By way of example, diluent-containing froth may have an asphaltene content of about 10 to 15 wt% on a total hydrocarbon basis, whereas paraffin-containing froth may have an asphaltene content of about 80-85 wt% on a total hydrocarbon basis. Thus, the bitumen froth originating from paraffinic froth treatment tailings would be of lower quality and thus may be different to process or separate to meet diluted bitumen product specifications. In addition, for paraffinic solvent, the floatation and stripping stages could be adapted in terms of operating conditions to tailor the separation processes to the different composition and properties compared to naphthenic diluent. Other techniques can thus be used with such paraffin-containing froth streams in order to deal with the higher asphaltene content, either by removing asphaltenes or re-dissolving the asphaltenes within the hydrocarbon phase.

[0065] The vapor overhead stream (38) can also be subjected to further processing. In one example, the vapor overhead stream (38) can be subjected to processing that includes either destruction or recovery of the light hydrocarbons present in the stream.
Regarding destruction of the light hydrocarbons, various methods can be used, such as bio-filtration or oxidation. Oxidation can include thermal oxidation via combustion (60) or incineration, as illustrated, catalytic oxidation. A reverse flow reactor (RFR) could also be used. The light hydrocarbons can also be used as fuel gas in order to produce energy (62), which can be utilized within the general oil sands processing plant or within the particular pretreatment facility for treating FTT-affected tailings. Various methods can be used, particularly those that are suitable for destroying light hydrocarbons, such as diluent.

[0066] Alternatively, the light hydrocarbons can be recovered from the vapor overhead stream (38). The vapor overhead stream (38) can thus be separated from the air for reuse. For example, the separation can include condensation using a condenser (64) in order to condense the light hydrocarbons contained in the vapor overhead stream to produce hydrocarbon depleted air and liquid light hydrocarbons (66) that can be recycled back into froth treatment or another part of the oil sands processing facility. Other separation techniques can also be used for light hydrocarbon recovery, such as absorption, adsorption (e.g., zeolite based or activated carbon based), and/or membrane separation. One or more of the techniques described in the following reference can be used: Removal of Volatile Organic Compounds from polluted air, Faisal I. Khan and Aloke Kr. Ghosal, Journal of Loss Prevention in Process Industries 13, 527-545, 2000.
When the light hydrocarbons include diluent, the recovered liquid diluent (66) can be recycled back into the froth treatment process. Alternatively, the recovered liquid diluent could be utilized in the froth processing (58) in order to enhance separation of the bitumen from the water and solids in that froth stream.

[0067] Turning now to Figures 2 and 3, alternative implementations of the two-stage pre-treatment will be described in which at least one in situ treatment is performed. While the implementation shown in Figure 1 includes two ex situ vessels that are operated to perform the two-stage pre-treatment of floatation followed by stripping, the implementations in Figures 2 and 3 employ an in situ treatment within the pond (12) itself. in this regard, it should be noted that an in situ treatment can be performed in the pond (12) and the resulting tailings material can be used in the process as described above and illustrated in Figure 1, where floatation and stripping vessel are used.

[0068] Referring to Figure 2, in one implementation, the floatation stage is performed in situ within the pond (12). The air inlet (24) of the floatation stage is thus provided within the pond itself and bitumen is floated upward to the surface of the pond (12) to form a bitumen froth material which is not removed as an overflow stream per se although bitumen skimming from the ponds could be performed. The bitumen depleted tailings (28) can then be retrieved from the pond (12) and supplied via the pump (16) to an ex situ stripping vessel 32 similar to the one illustrated in Figure 1. The air can be supplied via an in situ sparger (68) that is positioned along with the retrieval inlet (70) so that bitumen depleted tailings can be formed and retrieved from the pond (12). In situ floatation can provide advantages in terms of lower capital costs and equipment requirements for performing the floatation stage of the pre-treatment process, while ex situ flotation can facilitate enhanced process control and adaptability.

[0069] In situ methods within tailings ponds offer the option of a more gentle and slow treatment. For example, surface processing equipment would typically have retention times of minutes to hours, and this means that any process step would ideally have fast kinetics, implying for example higher mechanical energy input. In situ methods within tailings ponds may have retention times of months to years and are therefore compatible with much slower kinetics. As the ponds are already in existence, in situ methods can leverage this fact and use the ponds as vessel-like structure to perform the desired separation steps.

[0070] Referring to Figure 3, in another implementation, the floatation and stripping stages are performed in situ within the pond (12). For this alternative implementation, the floatation and stripping units can employ treatment cells (72, 74) that can be caisson-type cells. The treatment cells (72, 74) can be box-type that is set down on a prepared base within the pond or an open-type that has no bottom face. Each in situ treatment cell (72, 74) can be operated in a similar manner to the ex situ floatation and stripping stages as described further above.

[0071] When multiple in situ vessels are used, material can be pumped between the vessels and then once the pre-treatment is complete the cleaned tailings would be pumped to the dewatering operation. Floated bitumen could be recovered (e.g., via skimming) and processed in a similar way as for land-based equipment.

[0072] In terms of benefits of using in situ vessels within the tailings pond, the shore-based real estate required for the vessels is reduced or eliminate and pond-based infrastructure could be mobile. Mines, such as oil sands mines, are usually space-constrained as footprint is either used for tailings storage or consists of ore to be mined.
Locating infrastructure, such as in situ vessels (e.g., caisson-type vessels), within the ponds avoids potential issues with mine development. In addition, providing mobile vessels within the pond can enable the vessels to be moved towards the fluid tailings that require processing, thus eliminating some pumping or dredging requirements from the pond to the given vessel.

[0073] In terms of deployment and operation, the caisson in situ vessels can first be floated to the desired MFT location and lowered into the material. Dilution water can be sourced from the top of the pond and introduced within the MET in the caisson.
Air can be introduced at the bottom of the caisson. An agitator can be provided within the caisson for providing mechanical energy to the mixture. Floated bitumen can be selectively removed (e.g., via a skimmer) at the top of the caisson. Vapour can be recovered from the head space of the caisson. The cleaned tailings formed within the caisson can be pumped to dewatering operation via a pipeline.

[0074] Various different types of ex situ and in situ vessels and equipment can be used to implement the two-stage floatation and stripping pre-treatment process. In one example, a conventional oil sands slurry floatation cell (76) can be used for one or both of the flotation and stripping stages. An example of such a flotation cell is illustrated in Figure 4 and has a tailings inlet, a conical bottom, and outlets for the underflow and an upper stream. Air can be provided via a sparger that is located within a lower part of the vessel, or introduced with the tailings feed, or a combination thereof.

[0075] Alternatively, a simple lower-cost container-type vessel can be used, such as a BakerTM tank (78), which is a simple vessel with the necessary inlets and outlets and optionally with integrated wheels for mobility and features for being mounted and hauled via truck. An example of this type of vessel is illustrated in Figure 5. Such simple vessels can have some benefits since vessels can be swapped out for maintenance, allowing for a convenient sparing philosophy, has operated for a certain time period and has lower performance it can simply be swapped out for a new vessel and the old vessel can simply be disposed of.

[0076] Another alternative type of vessel is a Jameson Cell (80), an example of which is illustrated in Figure 6. In this example, air bubbles are not supplied using a sparger within the main chamber of the floatation vessel, but rather using a downcomer (82) which enables intense contact between air bubbles entering the air inlet (84) and tailings that are being jetted through an orifice (86). In the downcomer (82), the jet of liquid shears and entrains air from the atmosphere and the jet plunges into a liquid column where the kinetic energy mixes the air and tailings together to form fine air bubbles which collide with the particles. The material then enters the main separation chamber (88) in which the air and bitumen froth rise and form an upper froth zone (90) that overflows to form the froth overflow stream (26) while bitumen depleted tailings are withdrawn from the underflow outlet. While a single downcomer is shown in Figure 6, it is noted that the Jameson Cell type separator can have multiple downcomers that enter the same main separation chamber.

[0077] In the example shown in Figure 6, the Jameson Cell is used as a floatation unit (18), which can be advantageous since the floatation stage particularly benefits from high intensity mixing. In addition, a Jameson Cell can also be used for the stripping stage and appropriate adaptations can be made, such as providing an overhead collection system to collect the overhead vapour stream for further processing, if desired.

[0078] It is noted that the floatation and stripping vessels can be the same or different types of vessels. When using the same type of vessel, maintenance and replacement of vessels can be facilitated. Alternatively, each stage can use a different type of vessel that is specially adapted for the corresponding purpose and type of separation that is desired. It is also noted that air bubbles can be provided using various mechanisms, such as spargers, upstream mixers, downcomers, and so on. The separation vessels can have additional features, such as a pump around, agitators, internal baffles, etc., if desired. In addition, the inlets and outlets of the separation vessels can have various different structures and features. For example, the froth collection system to recover froth overflow can include an overflow weir and/or a bitumen skimmer device at the top of the vessel.

[0079] Referring now to Figure 7, one or both of the floatation and stripping vessels can include a roof (92) and a vapour overhead line (94) to withdraw vapours.
The roof (92) can be flat or domed and can be configured to provide a seal with the chamber to retain vapours within the upper portion of the vessel and thus allow the vapours to be safely withdrawn via the vapour overhead line (94). Thus, the floatation unit can include the roof (92) and vapour overhead line (94) to recover light hydrocarbons that may separate from the bitumen and/or tailings and report to the upper part of the vessel. In addition, the stripping unit can include a froth purge line located in an upper part of the vessel to withdraw any froth that may accumulate in the vessel. Froth purging from the stripping unit can be done continuously or periodically. It is also noted that the two-stage system can be implemented where the floatation vessel and the stripper are substantially similar or identical in terms of construction and equipment but would be operated using certain different operating parameters (e.g. mixing energy, air flow rates).

[0080] It should be noted that various different types of vessels and equipment could be used to implement the two-stage process described herein. Only some possible separators have been discussed above. Other types of vessels that could be used are separators that are typically used for mining applications or separators that are typically used for oil cleanup applications. Such separators do not have to be specially designed for a two-stage process such that one described herein. In addition, such separators do not have to be treated as a fixed asset of the plant or the overall processing operation but can be treated as a piece of temporary remediation equipment. For example, deployment of the separator may include providing a temporary foundation, that can be made of wooden beams and rig mats rather than a concrete foundation. The separator could also be on wheels to facilitate mobilization and relocation. Thus, the separators that are used for the two-stage process described herein can have a design and deployment strategy that is relatively different from those employed in conventional large-scale oil sands mining and extraction operations.

[0081] In terms of process control, the floatation and stripping stages can be operated using feedback or feedforward control strategies based on measurements regarding diluent content taken from any of the tailings or hydrocarbon streams in the process. For example, light hydrocarbons can be detected and/or measured in one or more tailings streams and the stages can be operated to achieve a certain light hydrocarbon removal level. In addition, vapours could be detected or measured from the second stage, and used as a metric for determining whether cleaning has sufficiently progressed by detecting or measuring the residual concentration of light hydrocarbons in the gas phase.

[0082] In an alternative implementation, as shown in Figure 8, the order of the floatation and stripping stages can be reversed, such that the FIT-affected tailings are first subjected to stripping and then a light hydrocarbon stripped tailings material is subjected to floatation to remove bitumen as froth overflow.

[0083] Referring to Figure 8, the FIT-affected tailings (14) can be withdrawn from a tailings pond (12) or another tailings source (95) and supplied via the pump 16 to an alternative two-stage diluent separation system (17A). In the first stage of system (17A), a first stage stripping unit (96) is used to remove light hydrocarbons from the tailings to produce a stripped tailings stream (98) and an overhead vapour (100).
Stripping air (102) can be injected at conditions that facilitate stripping of light hydrocarbons, while not emphasizing floatation of bitumen. Some bitumen can still be floated to form a froth material that can be removed as a first stage froth (104). It is also noted that dilution water (106) added to the tailings feed can be provided to provide a desired rheology for the tailings to facilitate stripping of light hydrocarbons.

[0084] The stripped tailings stream (98) can then be supplied to a second stage floatation unit (108) where floatation air (110) is provided to facilitate floatation of bitumen remaining in the tailings material. The second stage floatation unit (108) produces a cleaned tailings stream (112), a bitumen froth stream (114) and optionally a gas overhead stream (116). The stripped tailings stream (98) can also be diluted with second stage dilution water (118) to provide desired rheological conditions for the floatation stage. The floatation unit can be operated (e.g., air injection, residence time, temperature, pressure, relative feed rates of inputs, vessel sizing, bitumen content, rheology, etc.) can be provided to promote floatation of a substantial proportion of the bitumen remaining in the tailings in order to produce the cleaned tailings having a light hydrocarbon content meeting a desired level.

[0085] Still referring to Figure 8, the cleaned tailings (112) are then supplied to a dewatering operation that can include the addition of one or more dewatering chemicals (120) followed by discharging into a containment structure (122) (e.g., a mine pit) for settling and consolidation. The dewatering operation may be conducted to form a PASS
(52), as described above, with a settled solids layer (54) and a water cap (56).

[0086] Regarding the order of stages for the two-stage process, depending on various factors it may be desirable to select a certain order, i.e., flotation followed by stripping or stripping followed by floatation. For example, if froth recovery is to be minimized due to quality concerns or it is desired to prioritize recovery of light components from the tailings, it can be advantageous to perform stripping first. The initial tailings material has a high content of volatile components which tend to evaporate quickly, and thus a first-stage stripping treatment would result in larger qualities of light hydrocarbons being removed and recovered selectively. Thus, if maximizing the recovery of light hydrocarbons is prioritized over bitumen froth recovery, then it can be preferred to perform stripping first. On the other hand, if froth recovery is prioritized over light hydrocarbon recovery, then it may be preferred to perform floatation as the first stage followed by stripping.

[0087] The driving force for stripping would be higher with material with higher initial light hydrocarbon content. Therefore, in principle, the maximum removal of light hydrocarbons per volume of supplied air would be achieved if stripping is performed prior to floatation. A drawback of a first-stage stripping process implementation is that stripped light hydrocarbons can be lost, whereas light hydrocarbons recovered in a bitumen froth material could be more readily available for reprocessing. Stripping may be done first for scenarios where floatation is not commercially practical, e.g., when bitumen froth quality very poor or it cannot be reprocessed. In terms of froth quality, it can be considered that a froth with below 15 wt% bitumen is of poor quality and can be considered waste material, while froth with a bitumen content above 50 wt% can be considered normal and can in some cases be supplied back into a bitumen extraction facility without additional treatment. Froth with bitumen contents between 30 wt% and 50 wt% can be considered lower quality but in many cases can be subjected to reprocessing to produce an upgraded froth that can be recycled back into a bitumen extraction facility.
Of course, reprocessing of froth having a bitumen content above 15 wt% and below 40 or 50 wt%
can be assessed on a case-by-case basis.

[0088] As noted above, the light hydrocarbons described herein can include naphthenic diluent and/or paraffinic solvents that can be used in froth treatment and are sufficiently non-volatile to remain in the tailings at atmospheric conditions.
It is also noted that the light hydrocarbons can also be defined using boiling point ranges or bio-availability based on certain standards. For example, the light hydrocarbons can be defined as including a hydrocarbon fraction Fl as per the Canadian Counsel for Ministers of the Environment (CCME) standard, where Fl hydrocarbons include all extractable hydrocarbons that have a boiling point between the normal straight chain hydrocarbons C6 and nClo. The Fl hydrocarbons can also be used as a proxy for diluent and solvent in tailings materials. The light hydrocarbons can also be defined as Fl hydrocarbons in addition to pentane, for example if pentane is present in the tailings.
Other lighter hydrocarbons, such as propane, that could be present during upstream bitumen processing would not remain in the tailings due to volatility.
EXPERIMENTS & RESULTS

[0089] A number of experiments were conducted to assess operating parameters and performance for removing diluent from FTT affected MET.

[0090] Certain characteristics including hydrodynamic parameters (air flow rate, superficial velocity, gas holdup, bubble size), temperature, pressure, and tailings slurry composition and rheology were assessed for potential impact on the separation processes. The actual hydrocarbon composition (naphtha:bitumen, as well as naphtha composition) were assessed as well, and is a relevant design input for the process and vessels. Effects of diluent and bitumen content were also analyzed.

[0091] The majority of the light hydrocarbons can be found dissolved within the bitumen of the tailings. It has been found that that diluent is not present as a free phase, but rather as a solution of diluent in bitumen and a small fraction dissolved in the water phase. This is a relevant factor for the design and implementation of diluent separation processes.

[0092] It was further found that ease of light hydrocarbon recovery was a strong function of both light hydrocarbon composition and light hydrocarbon-to-bitumen ratio.
Light hydrocarbons will partition between the vapour phase and the light hydrocarbon/bitumen phase following Raoult's law. It is observed that vapour phase recovery reduces with decreasing light hydrocarbon to bitumen ratios, and complete recovery can only be achieved asymptotically. This sets practical limits to the light hydrocarbon recovery through stripping.

[0093] Light hydrocarbon recovery was found to be dominated by total amount of stripping medium (e.g., air) supplied, and the effective mass transfer coefficient.
Recovery is a weak function of temperature and pressure.

[0094] The impact of dilution with water was also tested. It was found that dilution can be a relevant parameter to achieve desired recovery performance, particularly for thicker fine tailings materials. In one experiment, 2:1 dilution of pond MET with process effluent water provided adequate recovery performance and froth quality. At lower dilution levels for high solids content materials, it was found that recovery performance was reduced and froth quality suffered. Depending on the requirements of the given implementation, dilution could be tailored to promote certain froth quality and/or recovery performance.
Dilution can thus be used for a reduction of the yield stress of the tailings fluid. In addition, lower yield stress for stripping enhances the likelihood of making small bubbles, which can increase specific surface area and holdup. This facilitates enhanced efficiency of the supplied air. Lower yield stress for floatation enhances the ability for a bitumen/air agglomerate to separate from the fluid and be recovered as froth. Dilution can thus have an impact on both floatation and stripping stages.

[0095] Experimentation found that three notable parameters can be considered including: dilution (e.g., similar for both floatation and stripping), mechanical energy input (e.g., high for floatation, lower for stripping) and superficial gas velocity (e.g., low for floatation, higher for stripping). For floatation, the process is interested in bitumen recovery, which is typically described in literature by:
Rb = 1-exp(-k*t) with k a rate constant and t the floatation time. =

[0096] Figure 9 captures experimental data with the floatation rate constant on the y-axis and the design parameters (N=impeller speed [1/s], D=impeller diameter [m], Jg=superficial gas velocity [m/s]). The rate constant can be predicted using the factor of the x-axis shown in Figure 9, as these relationships can provide an appropriate basis for scale up. Since light hydrocarbon is dissolved in bitumen, bitumen recovery also enables diluent recovery.

[0097] Figure 10 shows a typical result regarding removal of progressive amounts of naphtha over time using stripping. In principle, arbitrarily low naphtha concentrations can be reached by continued stripping.

[0098] It is also noted that experimentation assessed superficial gas velocities and mechanical energy input for each of the two stages and determined certain practical and workable ranges as well as advantageous operational ranges. For instance, the floatation unit can be operated at superficial gas velocities of less than 1 cm/s, less than 0.5 cm/s, less than 0.3 cm/s or less than 0.2 cm/s while being above 0.1 or 0.15 cm/s;
and the agitation during floatation can be performed to provide mechanical agitation of at least 0.65 W/Kg, at least 1 W/Kg, at least 1.5 W/Kg, at least 5 W/Kg, and up to 8.3 W/Kg.
These ranges cover practical scenarios for sizing of the floatation vessel, but different mechanical energy input could be used if the vessel sizing were changed.
Regarding the stripping stage, the stripper vessel can be operated at superficial gas velocities above 1 cm/s, above 3 cm/s, above 5 cm/s, and up to 10 cm/s. The agitation for the stripper vessel can provide mechanical agitation above 0.1 W/Kg and below 1 W/Kg, below 0.8, 0.5 or 0.3 W/Kg, or another level to keep solids in suspension.

[0099] In addition, depending on the design of the vessels, there can be a trade-off between vessel size (which impacts retention time) and mechanical energy input. The vessel sizing also depends on the desired throughput. For example, the design can either use a larger vessel with a smaller motor for mechanical energy input, or a smaller vessel with a larger motor for mechanical energy input.

Claims

26

1. A process for treating froth treatment tailing (FTT) affected tailings that includes bitumen and naphthenic diluent, comprising:
retrieving FTT-affected tailings from a tailings pond;
diluting the FTT-affected tailings with water to produce diluted tailings;
subjecting the diluted tailings to floatation comprising providing air bubbles and agitation in a floatation vessel to produce a bitumen froth overflow stream and a bitumen depleted tailings stream that includes residual diluent that are withdrawn from the floatation vessel;
subjecting the bitumen depleted tailings stream to stripping comprising providing air bubbles in a stripper vessel to strip at least a portion of the residual diluent from the bitumen depleted tailings to produce a vapour overhead stream comprising air and diluent and a cleaned tailings stream having a diluent content below a threshold level, that are withdrawn from the stripper vessel; and subjecting the cleaned tailings to dewatering comprising:
adding an immobilization chemical and a flocculant to the cleaned tailings to produce a flocculated tailings material;
supplying the flocculated tailings material into a mine pit to form a permanent aquatic storage structure (PASS) that includes a settled solids-rich layer and a water cap.

2. The process of claim 1, wherein the FTT-affected tailings comprise mature fine tailings (MFT) retrieved from the tailings pond.

3. The process of claim 1 or 2, wherein the dilution is performed to reduce a yield stress of the diluted tailings to below 5 Pa.

4. The process of claim 1 or 2, wherein the dilution is performed to reduce a yield stress of the diluted tailings to below 3 Pa.

5. The process of claim 1 or 2, wherein the dilution is performed to reduce a yield stress of the diluted tailings to below 1 Pa.

6. The process of any one of claims 1 to 5, wherein the floatation comprises injection of air into the floatation vessel at superficial gas velocities of less than 1 cm/s.

7. The process of any one of claims 1 to 5, wherein the floatation comprises injection of air into the floatation vessel at superficial gas velocities of less than 0.5 cm/s.

8. The process of any one of claims 1 to 5, wherein the floatation comprises injection of air into the floatation vessel at superficial gas velocities of less than 0.2 cm/s.

9. The process of any one of claims 1 to 8, wherein the floatation comprises injection of air into the floatation vessel at superficial gas velocities above 0.1 cm/s and below 1 cm/s.

10. The process of any one of claims 1 to 8, wherein the floatation comprises injection of air into the floatation vessel at superficial gas velocities above 0.15 cm/s and below 0.5 cm/s.

11. The process of any one of claims 1 to 8, wherein the floatation comprises injection of air into the floatation vessel at superficial gas velocities above 0.15 cm/s and below 0.3 cm/s.

12. The process of any one of claims 1 to 11, wherein the agitation during floatation is performed to provide high-energy mechanical agitation of at least 0.65 W/Kg.

13. The process of any one of claims 1 to 11, wherein the agitation during floatation is performed to provide high-energy mechanical agitation of at least 1 W/Kg.

14. The process of any one of claims 1 to 11, wherein the agitation during floatation is performed to provide high-energy mechanical agitation of at least 1.5 W/Kg.

15. The process of any one of claims 1 to 11, wherein the agitation during floatation is performed to provide high-energy mechanical agitation of at least 5 W/Kg.

16. The process of any one of claims 1 to 15, wherein the agitation during floatation is performed to provide high-energy mechanical agitation of at most 8.3 W/Kg and above 0.65 W/Kg.

17. The process of any one of claims 1 to 16, wherein the stripping comprises injection of air into the stripper vessel at superficial gas velocities above 1 cm/s.

18. The process of any one of claims 1 to 16, wherein the stripping comprises injection of air into the stripper vessel at superficial gas velocities above 3 cm/s.

19. The process of any one of claims 1 to 16, wherein the stripping comprises injection of air into the stripper vessel at superficial gas velocities above 5 cm/s.

20. The process of any one of claims 1 to 19, wherein the stripping comprises injection of air into the stripper vessel at superficial gas velocities above 1 cm/s and up to cm/s.

21. The process of any one of claims 1 to 20, wherein agitation is provided in the stripper vessel during stripping to provide mechanical agitation above 0.1 W/Kg and below 1 W/Kg.

22. The process of claim 21, wherein the agitation provided in the stripper vessel is sufficient to keep mineral solids suspended.

23. The process of claim 21 or 22, wherein the agitation in the stripper vessel is provided at lower mechanical energies compared to the agitation in the floatation vessel.

24. The process of any one of claims 1 to 23, wherein the air in the stripper vessel is provided at higher superficial gas velocities compared to the air in the floatation vessel.

25. The process of any one of claims 1 to 24, further comprising adding a second tailings stream to the cleaned tailings, the second tailings stream being a non-FTT-affected tailings that does not contain substantial light hydrocarbons.

26. The process of any one of claims 1 to 25, further comprising subjecting the bitumen froth overflow to froth processing in order to produce at least one bitumen enriched component and at least one water and solid enriched component.

27. The process of any one of claims 1 to 25, further comprising supplying the bitumen froth overflow into an oil sands extraction facility.

28. The process of any one of claims 1 to 27, further comprising subjecting the diluent in the vapour overhead stream to destruction.

29. The process of claim 28, wherein the destruction comprises thermal or catalytic combustion in order to produce energy.

30. The process of any one of claims 1 to 27, further comprising subjecting the vapour overhead stream to diluent recovery.

31. The process of claim 30, wherein the diluent recovery comprises condensation of diluent to produce liquid diluent and diluent depleted air.

32. The process of claim 31, further comprising recycling the liquid diluent into a froth treatment operation or another unit of the oil sands extraction operation.

33. The process of any one of claims 1 to 32, wherein the FTT-affected tailings have a diluent content above 1000ppm upon retrieval from the tailings pond.

34. The process of any one of claims 1 to 32, wherein the FTT-affected tailings have a diluent content above 2000ppm upon retrieval from the tailings pond.

35. The process of any one of claims 1 to 34, wherein the floatation and the stripping are operated so that the diluent content of the cleaned tailings is below 250ppm so as to be suitable for the dewatering of the cleaned tailings.

36. The process of any one of claims 1 to 34, wherein the floatation and the stripping are operated so that the diluent content of the cleaned tailings is below 200ppm so as to be suitable for the dewatering of the cleaned tailings.

37. The process of any one of claims 1 to 34, wherein the floatation and the stripping are operated so that the diluent content of the cleaned tailings is below 150ppm so as to be suitable for the dewatering of the cleaned tailings.

38. The process of any one of claims 1 to 34, wherein the floatation and the stripping are operated so that the diluent content of the cleaned tailings is below 100ppm so as to be suitable for the dewatering of the cleaned tailings.

39. The process of any one of claims 1 to 34, wherein the floatation and the stripping are operated so that the diluent content of the cleaned tailings is below 80ppm so as to be suitable for the dewatering of the cleaned tailings.

40. The process of any one of claims 1 to 34, wherein the floatation and the stripping are operated so that the diluent content of the cleaned tailings is below the threshold level so as to be suitable for the dewatering of the cleaned tailings.

41. The process of any one of claims 35 to 40, wherein the floatation is operated such that between 40% and 80% of the diluent in the FTT-affected tailings are removed.

42. The process of any one of claims 35 to 40, wherein the floatation is operated such that between 50 and 75% of the diluent in the FTT-affected tailings are removed

43. The process of claim 41 or 42, wherein the stripping is operated such that between 50% and 90% of the residual diluent in the bitumen depleted tailings is removed.

44. The process of claim 41 or 42, wherein the stripping is operated such that between 55% and 80% of the residual diluent in the bitumen depleted tailings is removed.

45. The process of any one of claims 1 to 44, wherein the floatation and stripping are operated such that at least 90% of the diluent in the FTT-affected tailings has been removed from the cleaned tailings.

46. The process of any one of claims 1 to 45, wherein the floatation is performed using a single floatation vessel.

47. The process of any one of claims 1 to 45, wherein the floatation is performed using a series of multiple floatation vessels.

48. The process of any one of claims 1 to 47, wherein the stripping is performed using a single stripper vessel.

49. The process of any one of claims 1 to 47, wherein the stripping is performed using a series of multiple stripper vessels.

50. The process of any one of claims 1 to 49, wherein the floatation vessel or the stripper vessel or both each have a roof for retaining vapours within a chamber of the vessel.

51. The process of claim 50, wherein the floatation vessel or the stripper vessel or both each have a vapour outlet system for collecting and transporting vapours out of the chamber of the vessel.

52. A process for treating froth treatment tailing (FTT) affected tailings that includes bitumen and light hydrocarbons, comprising:
subjecting the FTT-affected tailings to floatation comprising providing gas bubbles therein to produce a bitumen froth material that floats upward and a bitumen depleted tailings material that includes light hydrocarbons;
subjecting the bitumen depleted tailings material to stripping comprising providing gas bubbles to strip at least a portion of the residual light hydrocarbons from the bitumen depleted tailings to produce an overhead vapour comprising air and light hydrocarbons and a cleaned tailings material; and subjecting the cleaned tailings material to dewatering comprising:
adding a flocculant to the cleaned tailings material to produce a flocculated tailings material;
discharging the flocculated tailings material into a sub-aerial deposition location to allow water to separate from flocculated solid material.

53. The process of 52, wherein the floatation or the stripping or both are performed in situ within a tailings pond.

54. The process of claim 53, wherein the floatation or the stripping or both employ caisson-type vessels deployed in the tailings pond.

55. The process of claim 52, wherein the floatation or the stripping or both are performed ex situ within a floatation vessel and a stripper vessel respectively.

56. The process of 52, wherein the floatation is conducted in situ, the bitumen depleted tailings material is retrieved from the tailings pond and supplied into a stripper vessel, and the stripper vessel is operated to produce an underflow stream of the cleaned tailings material and an overhead stream of the overhead vapour.

57. The process of any one of claims 52 to 56, wherein the light hydrocarbons comprise naphthenic diluent.

58. The process of any one of claims 52 to 57, wherein the light hydrocarbons comprise paraffinic solvent.

59. The process of any one of claims 52 to 58, wherein the dewatering further comprises adding an immobilization chemical to the cleaned tailings material.

60. The process of claim 59, wherein the dewatering further comprises discharging the flocculated tailings material into a mine pit as the sub-aerial deposition location to form a permanent aquatic storage structure (PASS) that includes a settled solids-rich layer and a water cap.

61. The process of any one of claims 52 to 60, wherein the dewatering further comprises discharging the flocculated tailings material in thin lifts onto a sloped deposition area as the sub-aerial deposition location to allow water to drain away from drying solid material.

62. The process of any one of claims 52 to 61, wherein the gas provided in the floatation or the stripping or both is air.

63. The process of any one of claims 52 to 62, wherein the FTT-affected tailings are provided to the floatation with a yield strength below 5 Pa.

64. The process of any one of claims 52 to 62, wherein the FTT-affected tailings are provided to the floatation with a yield strength below 1 Pa.

65. The process of claim 63 or 64, wherein the FTT-affected tailings is diluted to obtain the yield strength.

66. The process of claim 65, where the dilution is performed using process water.

67. A process for treating froth treatment tailing (FTT) affected tailings that includes bitumen and light hydrocarbons, comprising:
subjecting the FTT-affected tailings to stripping comprising providing gas bubbles to strip at least a portion of the residual light hydrocarbons from the tailings to produce an overhead vapour comprising air and light hydrocarbons and a stripped tailings material that includes residual bitumen;
subjecting the stripped tailings material to floatation comprising providing gas bubbles therein to produce a bitumen froth material that floats upward and a cleaned tailings material; and subjecting the cleaned tailings material to dewatering comprising:
adding a flocculant to the cleaned tailings material to produce a flocculated tailings material;
discharging the flocculated tailings material into a sub-aerial deposition location to allow water to separate from flocculated solid material.

68. The process of claim 67, wherein the FTT-affected tailings comprise mature fine tailings (MFT) retrieved from a tailings pond.

69. The process of claim 67 or 68, further comprising diluting the FTT-affected tailings to produce diluted tailings that are subjected to the stripping, wherein the dilution is performed to reduce a yield stress of the diluted tailings to below 5 Pa.

70. The process of claim 67 or 68, further comprising diluting the FTT-affected tailings to produce diluted tailings that are subjected to the stripping, wherein the dilution is performed to reduce a yield stress of the diluted tailings to below 1 Pa.

71. The process of any one of claims 67 to 70, wherein the stripping comprises agitation of the FTT-affected tailings sufficient to keep mineral solids suspended.

72. The process of claim 71, wherein the agitation for the stripping is provided at lower mechanical energies compared to agitation of the stripped tailings material provided in for the floatation.

73. The process of any one of claims 67 to 72, wherein the gas provided in the stripping is provided at higher superficial gas velocities compared to the gas provided for the floatation.

74. The process of any one of claims 67 to 73, further comprising adding a second tailings stream to the cleaned tailings, the second tailings stream being a non-FTT-affected tailings that does not contain substantial light hydrocarbons.

75. The process of any one of claims 67 to 74, further comprising collecting the overhead vapour.

76. The process of claim 75, further comprising subjecting light hydrocarbons in the overhead vapour to destruction.

77. The process of claim 76, wherein the destruction comprises thermal or catalytic combustion in order to produce energy.

78. The process of any one of claims 67 to 75, further comprising subjecting the overhead vapour to light hydrocarbon recovery.

79. The process of claim 78, wherein the light hydrocarbon recovery comprises condensation of light hydrocarbons to produce liquid light hydrocarbons and light hydrocarbon depleted air.

80. The process of claim 79, further comprising recycling the liquid light hydrocarbons into a froth treatment operation or another unit of the oil sands extraction operation.

81. The process of any one of claims 67 to 80, wherein the FTT-affected tailings have a light hydrocarbon content above 1000ppm upon subjecting to the stripping.

82. The process of any one of claims 67 to 80, wherein the FTT-affected tailings have a light hydrocarbon content above 2000ppm upon subjecting to the stripping.

83. The process of any one of claims 67 to 82, wherein the stripping and the floatation are operated so that the light hydrocarbon content of the cleaned tailings is below 250ppm so as to be suitable for the dewatering of the cleaned tailings.

84. The process of any one of claims 67 to 82, wherein the floatation and the stripping are operated so that the diluent content of the cleaned tailings is below 200ppm so as to be suitable for the dewatering of the cleaned tailings.

85. The process of any one of claims 67 to 82, wherein the floatation and the stripping are operated so that the diluent content of the cleaned tailings is below 150ppm so as to be suitable for the dewatering of the cleaned tailings.

86. The process of any one of claims 67 to 82, wherein the floatation and the stripping are operated so that the diluent content of the cleaned tailings is below 100ppm so as to be suitable for the dewatering of the cleaned tailings.

87. The process of any one of claims 67 to 82, wherein the floatation and the stripping are operated so that the diluent content of the cleaned tailings is below 80ppm so as to be suitable for the dewatering of the cleaned tailings.

88. The process of any one of claims 67 to 82, wherein the floatation and the stripping are operated so that the diluent content of the cleaned tailings is below a threshold level so as to be suitable for the dewatering of the cleaned tailings.

89. The process of any one of claims 67 to 88, wherein the stripping and the floatation are operated such that at least 90% of the light hydrocarbons in the FTT-affected tailings has been removed from the cleaned tailings.

90. The process of any one of claims 67 to 89, wherein the floatation is performed using a single floatation vessel.

91. The process of any one of claims 67 to 89, wherein the floatation is performed using a series of multiple floatation vessels.

92. The process of any one of claims 67 to 91, wherein the stripping is performed using a single stripper vessel.

93. The process of any one of claims 67 to 91, wherein the stripping is performed using a series of multiple stripper vessels.

94. The process of any one of claims 67 to 89, wherein the floatation is performed using a floatation vessel, the stripping is performed using a single stripper vessel, and the floatation vessel or the stripper vessel or both have a roof for retaining vapours within a chamber of the vessel.

95. The process of claim 94, wherein the floatation vessel or the stripper vessel or both each have a vapour outlet system for collecting and transporting vapours out of the chamber of the vessel.

96. The process of any one of claims 67 to 95, wherein the stripping or the floatation or both are performed in situ.

97. The process of claim 67, wherein the stripping or the floatation or both are performed in situ within a tailings pond, and wherein the floatation or the stripping or both employ caisson-type vessels deployed in the tailings pond.

98. The process of claim 67, wherein the floatation or the stripping or both are performed ex situ within a floatation vessel and a stripper vessel respectively.

99. The process of any one of claims 67 to 98, wherein the light hydrocarbons comprise naphthenic diluent.

100. The process of any one of claims 67 to 98, wherein the light hydrocarbons comprise paraffinic solvent.

101. The process of any one of claims 67 to 100, wherein the dewatering further comprises adding an immobilization chemical to the cleaned tailings material.

102. The process of claim 101, wherein the dewatering further comprises discharging the flocculated tailings material into a mine pit as the sub-aerial deposition location to form a permanent aquatic storage structure (PASS) that includes a settled solids-rich layer and a water cap.

103. The process of any one of claims 67 to 102, wherein the dewatering further comprises discharging the flocculated tailings material in thin lifts onto a sloped deposition area as the sub-aerial deposition location to allow water to drain away from drying solid material.

104. The process of any one of claims 67 to 103, wherein the gas provided in the floatation or the stripping or both is air.

105. A system for treating froth treatment tailing (FTT) affected tailings that includes bitumen and light hydrocarbons, comprising:
a retrieval assembly comprising a pipeline and a pump for retrieving FTT-affected tailings from a tailings source;
a floatation unit comprising at least one floatation vessel in fluid communication with the retrieval assembly to receive the FTT-affected tailings, the floatation vessel comprising an air injection system for providing air bubbles, an agitation system for agitating the FTT-affected tailings, a froth outlet to withdraw a bitumen froth overflow stream and a tailings outlet to withdraw a bitumen depleted tailings stream that includes residual light hydrocarbons that are withdrawn from the floatation vessel;
a stripping unit comprising at least one stripper vessel to strip at least a portion of the residual light hydrocarbons from the bitumen depleted tailings, the stripper vessel having a tailings inlet in fluid communication with the tailings outlet of the floatation vessel, an air injection system for providing air bubbles, an upper outlet for releasing a vapour overhead comprising air and stripped light hydrocarbons and a tailings outlet for withdrawing a cleaned tailings stream; and a dewatering unit comprising:
a chemical addition assembly in fluid communication with the tailings outlet for receiving the cleaned tailings stream and adding an immobilization chemical and a flocculant thereto to produce a flocculated tailings material;

a pipeline coupled to the chemical addition assembly and configured to supply the flocculated tailings material into a mine pit to form a permanent aquatic storage structure (PASS) that includes a settled solids-rich layer and a water cap.

106. The system of claim 105, wherein the tailings source is a tailings pond.

107. The system of claim 106, wherein the retrieval assembly comprises a dredge or a barge.

108. The system of any one of claims 105 to 107, wherein the air injection system of the floatation unit comprises a sparger.

109. The system of any one of claims 105 to 108, wherein the agitation system of the floatation unit comprises an impeller.

110. The system of any one of claims 105 to 109, wherein the air injection system of the stripping unit comprises a sparger.

111. The system of any one of claims 105 to 110, wherein the stripping unit comprises an agitation system.

112. The system of claim 111, wherein the agitation system of the stripping unit comprises an impeller.

113. The system of any one of claims 105 to 112, wherein the retrieval assembly is configured to access mature fine tailings (MFT) from the tailings source to obtain the FTT-affected tailings.

114. The system of any one of claims 105 to 112, further comprising a dilution assembly configured to add a dilution liquid into the FTT-affected tailings prior to the floatation unit.

115. The system of claim 114, wherein the dilution assembly is configured to dilute the FTT-affected tailings to have a reduced yield strength below 5 Pa.

116. The system of claim 114, wherein the dilution assembly is configured to dilute the FTT-affected tailings to have a reduced yield strength below 1 Pa.

117. The system of any one of claims 105 to 116, wherein the air injection system of the floatation unit is configured to provide superficial gas velocities of less than 1 cm/s.

118. The system of any one of claims 105 to 116, wherein the air injection system of the floatation unit is configured to provide superficial gas velocities of less than 0.5 cm/s.

119. The system of any one of claims 105 to 116, wherein the air injection system of the floatation unit is configured to provide superficial gas velocities of less than 0.2 cm/s.

120. The system of any one of claims 105 to 116, wherein the air injection system of the floatation unit is configured to provide superficial gas velocities above 0.1 cm/s and below 0.5 cm/s.

121. The system of any one of claims 105 to 120, wherein the agitation system of the floatation unit is configured to provide mechanical agitation of at least 0.65 W/Kg.

122. The system of any one of claims 105 to 120, wherein the agitation system of the floatation unit is configured to provide mechanical agitation of at least 1 W/Kg.

123. The system of any one of claims 105 to 120, wherein the agitation system of the floatation unit is configured to provide mechanical agitation of at least 1.5 W/Kg.

124. The system of any one of claims 105 to 120, wherein the agitation system of the floatation unit is configured to provide mechanical agitation of at least 5 W/Kg.

125. The system of any one of claims 105 to 120, wherein the agitation system of the floatation unit is configured to provide mechanical agitation of at most 8.3 W/Kg and above 0.65 W/Kg.

126. The system of any one of claims 105 to 125, wherein the air injection system of the stripping unit is configured to provide superficial gas velocities above 1 cm/s.

127. The system of any one of claims 105 to 125, wherein the air injection system of the stripping unit is configured to provide superficial gas velocities above 5 cm/s.

128. The system of any one of claims 105 to 125, wherein the air injection system of the stripping unit is configured to provide superficial gas velocities above 1 cm/s and up to 10 cm/s.

129. The system of claim 111 or 112, wherein the agitation system of the stripping unit is configured to provide mechanical agitation above 0.1 W/Kg and below 1 W/Kg.

130. The system of claim 111, 112 or 129, wherein the agitation system of the stripping unit is configured to provide mechanical agitation to keep mineral solids suspended.

131. The system of claim 111, 112, 129 or 130, wherein the agitation system of the stripping unit is configured to provide lower mechanical energies compared to the agitation system in the floatation unit.

132. The system of any one of claims 105 to 131, wherein the air injection system of the stripping unit is configured to provide higher superficial gas velocities compared to the air injection system of the floatation unit.

133. The system of any one of claims 105 to 132, further comprising an addition line configured to add a second tailings stream to the cleaned tailings, the second tailings stream being a non-FTT-affected tailings that does not contain substantial light hydrocarbons.

134. The system of any one of claims 105 to 133, further comprising a froth reprocessing assembly configured for subjecting the bitumen froth overflow to froth processing in order to produce at least one bitumen enriched component and at least one water and solid enriched component.

135. The system of any one of claims 105 to 134, further comprising a vapour overhead treatment assembly configured for processing at least a portion of the vapour overhead.

136. The system of claim 135, wherein the vapour overhead treatment assembly comprises a combustion system to enable thermal or catalytic combustion of light hydrocarbons in the vapour overhead.

137. The system of claim 135, wherein the vapour overhead treatment assembly comprises a light hydrocarbon recovery system.

138. The system of claim 137, wherein the light hydrocarbon recovery system comprises a condenser to condense light hydrocarbons to produce recovered liquid and light hydrocarbon depleted air.

139. The system of any one of claims 105 to 138, wherein the FTT-affected tailings have a light hydrocarbon content above 1000ppm upon retrieval from the tailings source, and wherein the floatation and stripping units are configured to be operated so that the light hydrocarbon content of the cleaned tailings is below 250ppm so as to be suitable for the dewatering of the cleaned tailings.

140. The system of any one of claims 105 to 138, wherein the FTT-affected tailings have a light hydrocarbon content above 2000ppm upon retrieval from the tailings source, and wherein the floatation and stripping units are configured to be operated so that the light hydrocarbon content of the cleaned tailings is below 250ppm so as to be suitable for the dewatering of the cleaned tailings.

141. The system of any one of claims 105 to 138, wherein the FTT-affected tailings have a light hydrocarbon content above 1000ppm upon retrieval from the tailings source, and wherein the floatation and stripping units are configured to be operated so that the light hydrocarbon content of the cleaned tailings is below 200ppm so as to be suitable for the dewatering of the cleaned tailings.

142. The system of any one of claims 105 to 138, wherein the FTT-affected tailings have a light hydrocarbon content above 1000ppm upon retrieval from the tailings source, and wherein the floatation and stripping units are configured to be operated so that the light hydrocarbon content of the cleaned tailings is below 150ppm so as to be suitable for the dewatering of the cleaned tailings.

143. The system of any one of claims 105 to 138, wherein the FTT-affected tailings have a light hydrocarbon content above 1000ppm upon retrieval from the tailings source, and wherein the floatation and stripping units are configured to be operated so that the light hydrocarbon content of the cleaned tailings is below 100ppm so as to be suitable for the dewatering of the cleaned tailings.

144. The system of any one of claims 105 to 138, wherein the FTT-affected tailings have a light hydrocarbon content above 1000ppm upon retrieval from the tailings source, and wherein the floatation and stripping units are configured to be operated so that the light hydrocarbon content of the cleaned tailings is below 80ppm so as to be suitable for the dewatering of the cleaned tailings.

145. The system of any one of claims 105 to 138, wherein the FTT-affected tailings have a light hydrocarbon content above 1000ppm upon retrieval from the tailings source, and wherein the floatation and stripping units are configured to be operated so that the light hydrocarbon content of the cleaned tailings is below a threshold level so as to be suitable for the dewatering of the cleaned tailings.

146. The system of claim 145, wherein the floatation unit is configured to operate such that between 40% and 80% of the light hydrocarbon in the FTT-affected tailings are removed.

147. The system of claim 145, wherein the floatation unit is configured to operate such that between 50% and 75% of the light hydrocarbon in the FTT-affected tailings are removed.

148. The system of claim 145, wherein the stripping unit is configured to operate such that between 50% and 90%of the residual light hydrocarbon in the bitumen depleted tailings is removed.

149. The system of claim 145, wherein the stripping unit is configured to operate such that between 55% and 80%of the residual light hydrocarbon in the bitumen depleted tailings is removed.

150. The system of any one of claims 105 to 149, wherein the floatation and stripping units are configured to operate such that at least 90% of the light hydrocarbons in the FTT-affected tailings has been removed from the cleaned tailings, or the light hydrocarbon content is brought below a predetermined threshold.

151. The system of any one of claims 105 to 150, wherein the floatation unit comprises a single floatation vessel.

152. The system of any one of claims 105 to 150, wherein the floatation unit comprises a series of multiple floatation vessels.

153. The system of any one of claims 105 to 152, wherein the stripping unit comprises a single stripper vessel.

154. The system of any one of claims 105 to 152, wherein the stripping unit comprises a series of multiple stripper vessels.

155. The system of any one of claims 105 to 154, wherein the floatation vessel or the stripper vessel or both each have a roof for retaining vapours within a chamber of the vessel.

156. The system of claim 155, wherein the floatation vessel or the stripper vessel or both each have a vapour outlet system for collecting and transporting vapours out of the chamber of the vessel.

157. The system of any one of claims 105 to 131, wherein the light hydrocarbons comprise naphthenic diluent.

158. The system of any one of claims 105 to 131, wherein the light hydrocarbons comprise paraffinic solvent.

159. The system of claim 158, wherein the paraffinic solvent comprises a C5 tO

al kane.

160. The system of claim 158, wherein the paraffinic solvent comprises pentane.

161. A system for treating froth treatment tailing (FTT) affected tailings that includes bitumen and light hydrocarbons, comprising:
a retrieval assembly comprising a pipeline and a pump for retrieving FTT-affected tailings from a tailings source;
a stripping unit comprising at least one stripper vessel comprising a tailings inlet in fluid communication with the retrieval assembly to receive the FTT-affected tailings, an air injection system for providing air bubbles to strip a portion of the light hydrocarbons from the FTT-affected tailings, an upper outlet for releasing a vapour overhead comprising air and stripped light hydrocarbons and a tailings outlet for withdrawing a light hydrocarbon depleted tailings stream that includes residual bitumen;
a floatation unit comprising at least one floatation vessel comprising a tailings inlet in fluid communication with the tailings outlet of the stripping vessel to receive the light hydrocarbon depleted tailings stream, an air injection system for providing air bubbles to generate a bitumen froth, an agitation system for agitating the light hydrocarbon depleted tailings stream, a froth outlet to withdraw a bitumen froth overflow stream and a tailings outlet to withdraw a cleaned tailings stream;
a dewatering unit comprising:
a chemical addition assembly in fluid communication with the tailings outlet for receiving the cleaned tailings stream and adding an immobilization chemical and a flocculant thereto to produce a flocculated tailings material;
a pipeline coupled to the chemical addition assembly and configured to supply the flocculated tailings material into a mine pit to form a permanent aquatic storage structure (PASS) that includes a settled solids-rich layer and a water cap.

162. The system of claim 161, wherein the tailings source is a tailings pond.

163. The system of claim 162, wherein the retrieval assembly comprises a dredge or a barge.

164. The system of any one of claims 161 to 163, wherein the air injection system of the floatation unit comprises a sparger.

165. The system of any one of claims 161 to 164, wherein the agitation system of the floatation unit comprises an impeller.

166. The system of any one of claims 161 to 165, wherein the air injection system of the stripping unit comprises a sparger.

167. The system of any one of claims 161 to 166, wherein the retrieval assembly is configured to access mature fine tailings (MFT) from the tailings source to obtain the FTT-affected tailings.

168. The system of any one of claims 161 to 167, further comprising a dilution assembly configured to add a dilution liquid into the FTT-affected tailings prior to the stripping unit.

169. The system of claim 168, wherein the dilution assembly is configured to dilute the FTT-affected tailings to have a reduced yield strength below 5 Pa.

170. The system of claim 168, wherein the dilution assembly is configured to dilute the FTT-affected tailings to have a reduced yield strength below 1 Pa.

171. The system of any one of claims 161 to 170, wherein the air injection system of the floatation unit is configured to provide superficial gas velocities of less than 1 cm/s.

172. The system of any one of claims 161 to 170, wherein the air injection system of the floatation unit is configured to provide superficial gas velocities of less than 0.5 cm/s.

173. The system of any one of claims 161 to 170, wherein the air injection system of the floatation unit is configured to provide superficial gas velocities of less than 0.2 cm/s.

174. The system of any one of claims 161 to 170, wherein the air injection system of the floatation unit is configured to provide superficial gas velocities above 0.1 cm/s and below 1 cm/s.

175. The system of any one of claims 161 to 170, wherein the air injection system of the floatation unit is configured to provide superficial gas velocities above 0.1 cm/s and below 0.5 cm/s.

176. The system of any one of claims 161 to 170, wherein the air injection system of the floatation unit is configured to provide superficial gas velocities above 0.1 cm/s and below 0.3 cm/s.

177. The system of any one of claims 161 to 176, wherein the agitation system of the floatation unit is configured to provide mechanical agitation of at least 0.65 W/Kg.

178. The system of any one of claims 161 to 176, wherein the agitation system of the floatation unit is configured to provide mechanical agitation of at least 1 W/Kg.

179. The system of any one of claims 161 to 176, wherein the agitation system of the floatation unit is configured to provide mechanical agitation of at least 1.5 W/Kg.

180. The system of any one of claims 161 to 176, wherein the agitation system of the floatation unit is configured to provide mechanical agitation of at least 5 W/Kg.

181. The system of any one of claims 161 to 176, wherein the agitation system of the floatation unit is configured to provide mechanical agitation of at most 8.3 W/Kg and above 0.65 W/Kg.

182. The system of any one of claims 161 to 181, wherein the air injection system of the stripping unit is configured to provide superficial gas velocities above 1 cm/s.

183. The system of any one of claims 161 to 181, wherein the air injection system of the stripping unit is configured to provide superficial gas velocities above 5 cm/s.

184. The system of any one of claims 161 to 181, wherein the air injection system of the stripping unit is configured to provide superficial gas velocities above 1 cm/s and up to 10 cm/s.

185. The system of any one of claims 161 to 184, wherein the stripping unit further comprises an agitation system.

186. The system of claim 185, wherein the agitation system of the stripping unit comprises an impeller.

187. The system of claim 185 or 186, wherein the agitation system of the stripping unit is configured to provide mechanical agitation above 0.1 W/Kg and below 1 W/Kg.

188. The system of claim 185 or 186, wherein the agitation system of the stripping unit is configured to provide mechanical agitation to keep mineral solids suspended.

189. The system of claim 185 or 186, wherein the agitation system of the stripping unit is configured to provide lower mechanical energies compared to the agitation system in the floatation unit.

190. The system of any one of claims 161 to 189, wherein the air injection system of the stripping unit is configured to provide higher superficial gas velocities compared to the air injection system of the floatation unit.

191. The system of any one of claims 161 to 190, further comprising an addition line configured to add a second tailings stream to the cleaned tailings, the second tailings stream being a non-FTT-affected tailings that does not contain substantial light hydrocarbons.

192. The system of any one of claims 161 to 191, further comprising a froth reprocessing assembly configured for subjecting the bitumen froth overflow to froth processing in order to produce at least one bitumen enriched component and at least one water and solid enriched component.

193. The system of any one of claims 161 to 192, further comprising a vapour overhead treatment assembly configured for processing at least a portion of the vapour overhead.

194. The system of claim 193, wherein the vapour overhead treatment assembly comprises a combustion system to enable thermal or catalytic combustion of light hydrocarbons in the vapour overhead.

195. The system of claim 193, wherein the vapour overhead treatment assembly comprises a light hydrocarbon recovery system.

196. The system of claim 195, wherein the light hydrocarbon recovery system comprises a condenser to condense light hydrocarbons to produce recovered liquid and light hydrocarbon depleted air.

197. The system of any one of claims 161 to 196, wherein the FTT-affected tailings have a light hydrocarbon content above 1000ppm upon retrieval from the tailings source.

198. The system of any one of claims 161 to 196, wherein the FTT-affected tailings have a light hydrocarbon content above 2000ppm upon retrieval from the tailings source.

199. The system of claim 197 or 198, wherein the floatation and stripping units are configured to be operated so that the light hydrocarbon content of the cleaned tailings is below 250ppm so as to be suitable for the dewatering of the cleaned tailings.

200. The system of claim 197 or 198, wherein the floatation and stripping units are configured to be operated so that the light hydrocarbon content of the cleaned tailings is below 200ppm so as to be suitable for the dewatering of the cleaned tailings.

201. The system of claim 197 or 198, wherein the floatation and stripping units are configured to be operated so that the light hydrocarbon content of the cleaned tailings is below 150ppm so as to be suitable for the dewatering of the cleaned tailings.

202. The system of claim 197 or 198, wherein the floatation and stripping units are configured to be operated so that the light hydrocarbon content of the cleaned tailings is below 100ppm so as to be suitable for the dewatering of the cleaned tailings.

203. The system of claim 197 or 198, wherein the floatation and stripping units are configured to be operated so that the light hydrocarbon content of the cleaned tailings is below 80ppm so as to be suitable for the dewatering of the cleaned tailings.

204. The system of claim 197 or 198, wherein the floatation and stripping units are configured to be operated so that the light hydrocarbon content of the cleaned tailings is below a threshold level so as to be suitable for the dewatering of the cleaned tailings.

205. The system of any one of claims 161 to 204, wherein the floatation and stripping units are configured to operate such that at least 90% of the light hydorcarbons in the FTT-affected tailings has been removed from the cleaned tailings.

206. The system of any one of claims 161 to 205, wherein the floatation unit comprises a single floatation vessel.

207. The system of any one of claims 161 to 205, wherein the floatation unit comprises a series of multiple floatation vessels.

208. The system of any one of claims 161 to 207, wherein the stripping unit comprises a single stripper vessel.

209. The system of any one of claims 161 to 207, wherein the stripping unit comprises a series of multiple stripper vessels.

210. The system of any one of claims 161 to 209, wherein the floatation unit or the stripper unit or both each have a roof for retaining vapours within a chamber of the unit.

211. The system of claim 210, wherein the floatation unit or the stripper unit or both each have a vapour outlet system for collecting and transporting vapours out of the chamber of the unit.

212. The system of any one of claims 161 to 211, wherein the light hydrocarbons comprise naphthenic diluent.

213. The system of any one of claims 161 to 212, wherein the light hydrocarbons comprise paraffinic solvent.

214. The system of claim 213, wherein the paraffinic solvent comprises a C5 tO

al kane.

215. The system of claim 214, wherein the paraffinic solvent comprises pentane.

216. A process for treating froth treatment tailing (FTT) affected tailings that includes bitumen and light hydrocarbons, comprising:
subjecting the FTT-affected tailings to a multi-stage air bubbling process to produce at least one bitumen froth stream comprising bitumen and dissolved light hydrocarbons, vapour overhead comprising light hydrocarbons and air, and a cleaned tailings material that are depleted in light hydrocarbons;
dewatering the cleaned tailings, wherein the dewatering comprises:
adding an immobilization chemical and a flocculant to the cleaned tailings to produce a flocculated tailings material;
pipelining the flocculated tailings material into a containment earthwork structure to form a permanent aquatic storage structure (PASS) that includes a settled solids-rich layer and a water cap.

217. The process of claim 216, wherein the multi-stage air bubbling process comprises floatation followed by stripping.

218. The process of claim 216, wherein the FTT-affected tailings comprise mature fine tailings (MFT) retrieved from a tailings pond.

219. The process of claim 216 or 218, wherein the FTT-affected tailings are subjected to dilution prior to multi-stage air bubbling process.

220. The process of claim 219, wherein the dilution is performed to reduce a yield stress of the FTT-affected tailings to below 3 Pa.

221. The process of any one of claims 218 to 220, wherein the multi-stage air bubbling process comprises a first stage that includes injection of air into the FTT-affected tailings at superficial gas velocities of less than 0.5 cm/s and more than 0.1 cm/s.

222. The process of claim 221, wherein the first stage includes mechanical agitation of the FTT-affected tailings of at least 1.5 W/Kg and at most 8.3 W/Kg.

223. The process of claim 221 or 222, wherein the multi-stage air bubbling process comprises a subsequent stage downstream of the first stage, and the subsequent stage comprises injection of air into the FTT-affected tailings at superficial gas velocities above 1 cm/s and up to 10 cm/s.

224. The process of claim 223, wherein the subsequent stage comprises mechanical agitation of the FTT-affected tailings above 0.1 W/Kg and below 1 W/Kg.

225. The process of claim 224, wherein the mechanical agitation provided in the subsequent stage is sufficient to keep mineral solids suspended.

226. The process of claim 224 or 225, wherein the mechanical agitation in the subsequent stage is at lower mechanical energies compared to the mechanical agitation in the first stage.

227. The process of any one of claims 216 to 226, further comprising adding a second tailings stream to the cleaned tailings, the second tailings stream being a non-FTT-affected tailings that does not contain substantial light hydrocarbons.

228. The process of any one of claims 216 to 227, further comprising subjecting the bitumen froth stream to froth processing in order to produce at least one bitumen enriched component and at least one water and solid enriched component.

229. The process of any one of claims 216 to 228, further comprising supplying the bitumen froth stream into an oil sands extraction facility.

230. The process of any one of claims 216 to 229, further comprising subjecting the light hydrocarbons in the vapour overhead to destruction.

231. The process of claim 230, wherein the destruction comprises thermal or catalytic combustion in order to produce energy.

232. The process of any one of claims 216 to 229, further comprising subjecting the vapour overhead to light hydrocarbons recovery.

233. The process of claim 232, wherein the light hydrocarbons recovery comprises condensation of the light hydrocarbons in the vapour overhead to produce liquid light hydrocarbons and light hydrocarbons depleted air.

234. The process of claim 233, further comprising recycling the liquid vapour overhead into a froth treatment operation or another unit of the oil sands extraction operation.

235. The process of any one of claims 216 to 234, wherein the FTT-affected tailings have a diluent content above 1000ppm upon feeding into the multi-stage air bubbling process.

236. The process of any one of claims 216 to 235, wherein the FTT-affected tailings have a diluent content above 2000ppm upon feeding into the multi-stage air bubbling process.

237. The process of any one of claims 216 to 236, wherein the multi-stage air bubbling process is operated so that the light hydrocarbons content of the cleaned tailings is below 250ppm so as to be suitable for the dewatering of the cleaned tailings.

238. The process of any one of claims 216 to 236, wherein the multi-stage air bubbling process is operated so that the light hydrocarbons content of the cleaned tailings is below 200ppm so as to be suitable for the dewatering of the cleaned tailings.

239. The process of any one of claims 216 to 236, wherein the multi-stage air bubbling process is operated so that the light hydrocarbons content of the cleaned tailings is below 150ppm so as to be suitable for the dewatering of the cleaned tailings.

240. The process of any one of claims 216 to 236, wherein the multi-stage air bubbling process is operated so that the light hydrocarbons content of the cleaned tailings is below 100ppm so as to be suitable for the dewatering of the cleaned tailings.

241. The process of any one of claims 216 to 236, wherein the multi-stage air bubbling process is operated so that the light hydrocarbons content of the cleaned tailings is below 80ppm so as to be suitable for the dewatering of the cleaned tailings.

242. The process of any one of claims 216 to 236, wherein the multi-stage air bubbling process is operated so that the light hydrocarbons content of the cleaned tailings is below a threshold level so as to be suitable for the dewatering of the cleaned tailings.

243. The process of any one of claims 216 to 242, wherein the multi-stage air bubbling process is operated such that at least 90% of the light hydrocarbons in the FTT-affected tailings has been removed from the cleaned tailings.

244. The process of any one of claims 216 to 243, wherein each stage of the multi-stage air bubbling process is performed using a single vessel.

245. The process of any one of claims 216 to 243, wherein each stage of the multi-stage air bubbling process is performed using a series of multiple vessels.

246. The process of claim 244 or 245, wherein each vessel of the multi-stage air bubbling process has a roof for retaining vapours within a chamber of the vessel.

247. The process of claim 246, wherein each vessel has a vapour outlet system for collecting and transporting vapours out of the chamber of the vessel.

248. The process of 217, wherein the floatation or the stripping or both are performed in situ within a tailings pond.

249. The process of claim 216, wherein the multi-stage air bubbling process is performed in situ using caisson-type vessels deployed in a tailings pond.

250. The process of claim 216, wherein the multi-stage air bubbling process is performed ex situ.

251. The process of 216, wherein the multi-stage air bubbling process comprises an in situ stage followed by an ex situ stage.

252. The process of any one of claims 216 to 251, wherein the light hydrocarbons comprise naphthenic diluent.

253. The process of any one of claims 216 to 252, wherein the light hydrocarbons comprise paraffinic solvent.

254. A process for stripping froth treatment tailing (FTT) affected tailings that includes bitumen and light hydrocarbons, comprising:
providing gas bubbles to strip the light hydrocarbons from the FTT-affected tailings; and producing an overhead vapour comprising air and at least a portion of the light hydrocarbons and a stripped tailings material that includes residual bitumen.

255. The process of claim 254, wherein the FTT-affected tailings comprise mature fine tailings (MFT) retrieved from a tailings pond.

256. The process of claim 254 or 255, further comprising diluting the FTT-affected tailings to produce diluted tailings that are subjected to the stripping.

257. The process of claim 256, wherein the dilution is performed to reduce a yield stress of the diluted tailings to below 5 Pa.

258. The process of claim 256, wherein the dilution is performed to reduce a yield stress of the diluted tailings to below 1 Pa.

259. The process of any one of claims 254 to 258, wherein the stripping further comprises agitating the FTT-affected tailings sufficient to keep mineral solids suspended.

260. The process of any one of claims 254 to 259, further comprising collecting the overhead vapour.

261. The process of claim 260, further comprising subjecting light hydrocarbons in the overhead vapour to destruction.

262. The process of claim 261, wherein the destruction comprises thermal or catalytic combustion in order to produce energy.

263. The process of any one of claims 254 to 260, further comprising subjecting the overhead vapour to light hydrocarbon recovery.

264. The process of claim 263, wherein the light hydrocarbon recovery comprises condensation of light hydrocarbons to produce liquid light hydrocarbons and light hydrocarbon depleted air.

265. The process of claim 264, further comprising recycling the liquid light hydrocarbons into a froth treatment operation or another unit of the oil sands extraction operation.

266. The process of any one of claims 254 to 265, wherein the FTT-affected tailings have a light hydrocarbon content above 1000ppm upon subjecting to the stripping.

267. The process of any one of claims 254 to 265, wherein the FTT-affected tailings have a light hydrocarbon content above 2000ppm upon subjecting to the stripping.

268. The process of any one of claims 254 to 267, wherein the stripping is operated such that between 50% and 90%, or between 55% and 80%, of the light hydrocarbons in the FTT-affected tailings has been removed from the stripped tailings material.

269. The process of any one of claims 254 to 268, wherein the stripping is performed using a single stripper vessel.

270. The process of any one of claims 254 to 268, wherein the stripping is performed using a series of multiple stripper vessels.

271. The process of any one of claims 254 to 268, wherein the stripping is performed using a single stripper vessel, and the stripper vessel has a roof for retaining vapours within a chamber of the vessel.

272. The process of claim 271, wherein the stripper vessel has a vapour outlet system for collecting and transporting vapours out of the chamber of the stripper vessel.

273. The process of any one of claims 254 to 272, wherein the stripping is performed in situ.

274. The process of claim 254, wherein the stripping is performed in situ within a tailings pond, and the stripping employs a caisson-type vessel deployed in the tailings pond.

275. The process of claim 254, wherein the stripping is performed ex situ within a stripper vessel.

276. The process of any one of claims 254 to 275, wherein the light hydrocarbons comprise naphthenic diluent.

277. The process of any one of claims 254 to 275, wherein the light hydrocarbons comprise paraffinic solvent.

278. The process of any one of claims 254 to 277, wherein the gas provided in the stripping is air.

279. A system for treating froth treatment tailing (FTT) affected tailings that includes bitumen and light hydrocarbons, the system comprising:
a stripping unit comprising at least one stripper vessel comprising:
a tailings inlet to receive the FTT-affected tailings;
a gas injection system for providing gas bubbles to strip a portion of the light hydrocarbons from the FTT-affected tailings;
an upper outlet for releasing a vapour overhead comprising air and stripped light hydrocarbons; and a tailings outlet for withdrawing a cleaned tailings material that are depleted in light hydrocarbons and that include residual bitumen.

280. The system of claim 279, further comprising a retrieval assembly comprising a pipeline and a pump for retrieving FTT-affected tailings from a tailings source.

281. The system of claim 280, wherein the tailings source is a tailings pond.

282. The system of claim 281, wherein the retrieval assembly comprises a dredge or a barge.

283. The system of any one of claims 280 to 282, wherein the retrieval assembly is configured to access mature fine tailings (MFT) from the tailings source to obtain the FTT-affected tailings.

284. The system of any one of claims 279 to 283, wherein the stripping unit further comprises an agitation system.

285. The system of claim 284, wherein the agitation system of the stripping unit comprises an impeller.

286. The system of any one of claims 279 to 285, further comprising a dilution assembly configured to add a dilution liquid into the FTT-affected tailings prior to the stripping unit.

287. The system of claim 286, wherein the dilution assembly is configured to dilute the FTT-affected tailings to have a reduced yield strength below 5 Pa.

288. The system of claim 286, wherein the dilution assembly is configured to dilute the FTT-affected tailings to have a reduced yield strength below 1 Pa.

289. The system of any one of claims 279 to 288, wherein the gas injection system of the stripping unit comprises an air injection system.

290. The system of claim 289, wherein the air injection system of the stripping unit comprises a sparger.

291. The system of claim 289 or 290, wherein the air injection system of the stripping unit is configured to provide superficial gas velocities above 1 cm/s.

292. The system of any one of claims 289 to 291, wherein the air injection system of the stripping unit is configured to provide superficial gas velocities above 5 cm/s.

293. The system of any one of claims 289 to 291, wherein the air injection system of the stripping unit is configured to provide superficial gas velocities above 1 cm/s and up to 10 cm/s.

294. The system of claim 284 or 285, wherein the agitation system of the stripping unit is configured to provide mechanical agitation above 0.1 W/Kg and below 1 W/Kg.

295. The system of claims 284 or 285, wherein the agitation system of the stripping unit is configured to provide mechanical agitation to keep mineral solids suspended.

296. The system of any one of claims 279 to 295, further comprising an addition line configured to add a second tailings stream to the cleaned tailings material, the second tailings stream being a non-FTT-affected tailings that does not contain substantial light hydrocarbons.

297. The system of any one of claims 279 to 296, further comprising a vapour overhead treatment assembly configured for processing at least a portion of the vapour overhead.

298. The system of claim 297, wherein the vapour overhead treatment assembly comprises a combustion system to enable thermal or catalytic combustion of light hydrocarbons in the vapour overhead.

299. The system of claim 297, wherein the vapour overhead treatment assembly comprises a light hydrocarbon recovery system.

300. The system of claim 299, wherein the light hydrocarbon recovery system comprises a condenser to condense light hydrocarbons to produce recovered liquid and light hydrocarbon depleted air.

301. The system of any one of claims 280 to 300, wherein the FTT-affected tailings have a light hydrocarbon content above 1000ppm upon retrieval from the tailings source.

302. The system of any one of claims 280 to 300, wherein the FTT-affected tailings have a light hydrocarbon content above 2000ppm upon retrieval from the tailings source.

303. The system of any one of claims 279 to 302, wherein the stripping unit comprises a single stripper vessel.

304. The system of any one of claims 279 to 302, wherein the stripping unit comprises a series of multiple stripper vessels.

305. The system of any one of claims 279 to 303, wherein the stripper unit has a roof for retaining vapours within a chamber of the unit.

306. The system of claim 305, wherein the stripper unit has a vapour outlet system for collecting and transporting vapours out of the chamber of the unit.

307. The system of any one of claims 279 to 306, wherein the light hydrocarbons comprise naphthenic diluent.

308. The system of any one of claims 279 to 307, wherein the light hydrocarbons comprise paraffinic solvent.

309. The system of claim 308, wherein the paraffinic solvent comprises a C5 tO

al kane.

310. The system of claim 309, wherein the paraffinic solvent comprises pentane.