WO2018152613A1

WO2018152613A1 - Dewatering thick fine tailings using dilution and near infrared monitoring techniques

Info

Publication number: WO2018152613A1
Application number: PCT/CA2017/051493
Authority: WO
Inventors: Trevor Bugg; Enbo Feng; Ramesh Kadali; Bryan Adams; Marc Goranson; Naveen Prathap; Adrian Revington; Kushagra Mittal; Benito Moyls; John Diep
Original assignee: Suncor Energy Inc.
Priority date: 2017-02-24
Filing date: 2017-12-11
Publication date: 2018-08-30
Also published as: CA3053555A1; CA3053555C; CA2959035C; CA2959035A1

Abstract

A process for dewatering mature fine tailings derived from oil sands extraction is provided, including steps of obtaining a near-infrared (NIR) spectral measurement of the flow of mature fine tailings (MFT) in order to determine a clay content thereof, diluting the in-line MFT flow based on the NIR-derived clay content, subjecting the diluted flow to in-line homogenization using mixers, injecting a flocculant solution into the pre-treated MFT flow based on the clay content, and subsequently dewatering to produce an aqueous phase and a solids-enriched material.

Description

DEWATERING THICK FINE TAILINGS USING DILUTION AND NEAR INFRARED

MONITORING TECHNIQUES

TECHNICAL FIELD

[0001] The technical field generally relates to dewatering thick fine tailings, and more particularly to dewatering operations that include dilution and/or near infrared (NIR) based monitoring techniques.

BACKGROUND

[0002] Tailings are left over material derived from a mining extraction process. Tailings derived from mining operations, for example, oil sands mining, are often placed in dedicated disposal ponds for settling. The settling or separation of fine solids from the water is a relatively slow process. Due to the behaviour of fine solids in the aqueous phase, a material that can be referred to as "thick fine tailings" (TFT) is formed. TFT material mainly includes water and fine mineral solids. The fines are small solid particulates having various sizes up to about 44 microns. TFT material has a solids content with a fines portion sufficiently high such that the fines tend to remain in suspension in the water and the material has slow consolidation rates.

[0003] In some scenarios, the TFT can form in a tailings pond. When whole tailings (which include coarse solid material, fine solids, and water) or thin fine tailings (which include a relatively low content of fine solids and a high water content) are supplied to a tailings pond, the tailings separate by gravity into different layers over time. The bottom layer is predominantly coarse material, such as sand, and the top layer is predominantly water. The middle layer is relatively sand depleted, but still has a fair amount of fine solids suspended in the aqueous phase. This middle layer is an example of TFT, and is often referred to as "mature fine tailings" (MFT).

[0004] MFT can be formed from various different types of mine tailings that are derived from the processing of different types of mined ore. While the formation of MFT typically takes a fair amount of time (e.g., between 1 and 3 years under gravity settling conditions in the pond) when derived from certain whole tailings supplied form an extraction operation, it should be noted that MFT and MFT-like materials may be formed more rapidly depending on the composition and post-extraction processing of the tailings, which may include thickening or other separation steps that may remove a certain amount of coarse solids and/or water prior to supplying the processed tailings to the tailings pond.

[0005] Certain techniques have been developed for dewatering TFT. Dewatering of TFT can include contacting the thick fine tailings with a flocculant and then depositing the flocculated material on a sub-aerial deposition surface where the deposited material can release water and eventually dry.

[0006] In the context of dewatering TFT, there are a number of challenges related to the monitoring, handling, and management of the materials involved.

SUM MARY

[0007] In some implementations, there is a process for dewatering mature fine tailings (MFT) derived from oil sands extraction, the process comprising: providing an inline MFT flow; obtaining near infrared (NIR) spectral measurements of the MFT flow using NIR spectroscopy, to determine an NIR derived clay content of the MFT flow; diluting the in-line MFT flow with an aqueous stream based on the NIR derived clay content to produce a diluted MFT flow having a clay-to-water ratio (CWR) between about 0.25 and about 0.33; subjecting the diluted MFT flow to in-line homogenization in a series of in-line mixers to produce a pre-treated MFT flow; injecting an aqueous flocculant solution into the pre-treated MFT flow at a flocculant dosage based on the NIR derived clay content, to produce a flocculation material; and dewatering the flocculation material to produce an aqueous phase and a solids-enriched material.

[0008] In some implementations, the NIR spectral measurements are obtained online or at-line. In some implementations, the NIR spectral measurements are obtained using reflectance-type NIR spectroscopy.

[0009] In some implementations, the process includes determining the NIR derived clay content from the NIR spectral measurements in accordance with a pre-determined chemometric model correlating NIR spectral measurements and actual clay content of MFT samples.

[0010] In some implementations, diluting of the in-line MFT flow based on the NIR derived clay content is controlled according to feedforward control. [001 1] In some implementations, the CWR of the diluted MFT flow is a predetermined CWR value. In some implementations, diluting of the in-line MFT flow comprises injecting an aqueous stream co-directionally into the MFT flow. In some implementations, diluting of the in-line MFT flow comprises injecting the aqueous stream within a central region of the MFT flow. In some implementations, diluting of the in-line MFT flow is controlled by adjusting of a flowrate of the aqueous stream.

[0012] In some implementations, diluting of the in-line MFT flow is performed via multiple dilution inlets provided along a flowpath of the MFT flow, wherein the dilution inlets are controlled for injection via only one of the dilution inlets at a time.

[0013] In some implementations, there is provided a dilution unit for injecting a dilution fluid into thick fine tailings (TFT), the dilution unit comprising: a main pipe for transporting an in-line TFT flow; and at least one injector quill comprising: a feed pipe section extending into the main pipe and receiving a flow of the dilution fluid; and an outlet at a distal end of the feed pipe section, the outlet being configured and positioned within the main pipe to expel the dilution fluid co-directionally and within a central region of the TFT flow to produce a diluted TFT flow.

[0014] In some implementations, the outlet is positioned at a cross-sectional center- point of the main pipe.

[0015] In some implementations, the at least one injector quill comprises a first injector quill and a second injector quill. In some implementations, the first and second injector quills are located in spaced-apart relation to each other along a length of the main pipe. In some implementations, the first injector quill is sized and configured to provide lower flowrate of the dilution fluid compared to the second injector quill. In some implementations, the feed pipe section of the first injector quill has a smaller diameter than that of the feed pipe section of the second injector quill. In some implementations, the first injector quill is located upstream from the second injector quill. In some implementations, the first and second injector quills are configured for injection of the dilution fluid via only one of the injector quills at a time. In some implementations, the first and second injector quills further comprise a control assembly configured to control the flowrate of the dilution fluid injected into the TFT. In some implementations, the control assembly comprises valves and a controller configured to adjust the valves. [0016] In some implementations, the unit also includes a common dilution fluid header in fluid communication with the first and second injector quills for supplying dilution fluid thereto.

[0017] In some implementations, the feed pipe section is oriented at an oblique angle relative to the main pipe. In some implementations, the oblique angle is between about 60° and about 30° facing upstream of a flow direction. In some implementations, the oblique angle is about 45°.

[0018] In some implementations, the outlet is formed by an oblique cut through an end of the feed pipe section. In some implementations, the oblique cut is provided to form an annular surface of the outlet that is substantially normal to a length of the main pipe.

[0019] In some implementations, the outlet comprises a nozzle. In some implementations, the nozzle comprises an elbow-type nozzle that is oriented and positioned to point along a central longitudinal axis of the main pipe.

[0020] In some implementations, the unit also includes a bypass line configured to bypass at least a portion of the TFT past the at least one injector quill. In some implementations, the bypass line comprises: an inlet portion in fluid communication with the main pipe upstream of the at least one injector quill; an outlet portion in fluid communication with the main pipe downstream of the at least one injector quill; and a flow control assembly comprising valves or gates in order to provide or cease fluid communication with the main pipe.

[0021] In some implementations, the at least one injector quill is configured to provide sufficient dilution fluid to produce the diluted TFT flow having a clay-to-water ratio (CWR) within a CWR range between about 0.25 and about 0.33.

[0022] In some implementations, the at least one injector quill is configured to produce the diluted TFT flow having a target CWR value within the CWR range.

[0023] In some implementations, the TFT is derived from an oil sands extraction operation. [0024] In some implementations, the at least one injector quill is configured for injection of a liquid dilution stream comprising fresh water, process water, and/or recycle water streams from an extraction operation.

[0025] In some implementations, there is provided a pre-treatment system for pre- treating thick fine tailings (TFT) prior to flocculation and dewatering, the pre-treatment system comprising: a dilution unit for injecting a dilution fluid into a TFT flow to produce a diluted TFT flow; and a homogenization unit comprising: an upstream pipe section receiving the diluted TFT flow; a plurality of in-line mixers for subjecting the diluted TFT flow to mixing to produce a homogenized diluted TFT flow; and a downstream pipe section for supplying the homogenized diluted TFT flow to a flocculation unit. In some implementations, the dilution unit is as defined above or herein.

[0026] In some implementations, the dilution unit comprises one or more branch lines in fluid communication with the TFT flow to form one or more corresponding Tee junctions. In some implementations, the branch line is configured and operated such that a dilution fluid jet entering the TFT flow generally aligns with a central region of the TFT flow. In some implementations, the dilution unit comprises multiple sequential branch lines having different pipe diameters for providing different flowrates of the dilution fluid into the TFT flow. In some implementations, the dilution unit comprises multiple sequential side streams entering the TFT flow, and each side stream comprises multiple branch lines provided around the TFT flow for injection therein at different injection angles.

[0027] In some implementations, the in-line mixers are arranged in series. In some implementations, the in-line mixers comprise static mixers. In some implementations, at least eight of the static mixers are provided in series.

[0028] In some implementations, the upstream pipe section has a smaller diameter than a supply line supplying the diluted TFT thereto.

[0029] In some implementations, the dilution unit, the homogenization unit, and a connection conduit therebetween are configured such that the dilution fluid within the TFT remains generally spaced away from side walls of the connection conduit until the diluted TFT arrives at the homogenization unit. [0030] In some implementations, there is provided a process for dewatering thick fine tailings (TFT), comprising: supplying a TFT flow to the dilution unit as defined above or herein; supplying the diluted TFT flow to an in-line homogenization unit to produce a pre-treated TFT flow; subjecting the pre-treated TFT flow to flocculation to produce a flocculation material; and dewatering the flocculation material to produce an aqueous stream and a dewatered solids-enriched material.

[0031] In some implementations, there is provided a process for dewatering thick fine tailings (TFT), comprising: supplying a TFT flow to a dilution unit to produce a diluted TFT having a target clay content within a pre-determined clay-to-water (CWR) range; supplying the diluted TFT flow to an in-line homogenization unit to produce a pre- treated TFT flow; subjecting the pre-treated TFT flow to flocculation with a flocculant dosage based on the target clay content, to produce a flocculation material; and dewatering the flocculation material to produce an aqueous stream and a dewatered solids-enriched material.

[0032] In some implementations, the dilution unit is as defined above and/or herein.

[0033] In some implementations, the process also includes retrieving the TFT from a tailings source to produce the TFT flow which has variable clay content; monitoring clay content of the TFT flow on-line or at-line; and controlling the dilution unit in response to the variable clay content of the TFT flow via feedforward control, in order to maintain the target clay content.

[0034] In some implementations, the process also includes monitoring clay content of the diluted TFT and/or the pre-treated TFT; controlling the dilution unit in response to the clay content of the diluted TFT via feedback control, in order to maintain the target clay content.

[0035] In some implementations, there is provided a process for treating thick fine tailings (TFT), comprising: determining clay content of an in-line flow of the TFT using near infrared (NIR) spectrometry; injecting a flocculant into the TFT at a flocculant dosage based on the clay content of the TFT to produce a flocculation material; and dewatering the flocculation material to produce an aqueous stream and a dewatered flocculated material. [0036] In some implementations, the process includes diluting the TFT prior to injecting the flocculant. In some implementations, the diluting is performed upstream of the NIR spectrometry. In some implementations, the diluting is performed downstream of the NIR spectrometry. In some implementations, the diluting is controlled based on the clay content using NIR spectrometry, in order to obtain a diluted TFT flow having a target clay-to-water ratio (CWR) which is subjected to flocculation. In some implementations, the target CWR is within a CWR range between about 0.25 and about 0.33.

[0037] In some implementations, there process includes controlling dilution in response to the clay content via feedforward control, in order to maintain the target CWR. In some implementations, the process includes controlling dilution in response to the clay content via feedback control, in order to maintain a target clay content.

[0038] In some implementations, there is provided a process for treating thick fine tailings (TFT), comprising: determining clay content of an in-line flow of the TFT using near infrared (NIR) spectrometry; diluting the TFT based on the clay content determined by the NIR spectrometry to obtain a diluted TFT having a target clay content; injecting a flocculant into the TFT based on the target clay content of the diluted TFT, to produce a flocculation material; and dewatering the flocculation material to produce an aqueous stream and a dewatered solids-enriched material.

[0039] In some implementations, there is provided a process for treating thick fine tailings (TFT), comprising: diluting a TFT flow to obtain a diluted TFT; determining clay content of the diluted TFT using near infrared (NIR) spectrometry; controlling the diluting of the TFT flow based on the clay content determined by the NIR spectrometry, to maintain a target clay content of the diluted TFT; injecting a flocculant into the diluted TFT, to produce a flocculation material; and dewatering the flocculation material to produce an aqueous stream and a dewatered solids-enriched material.

[0040] In some implementations, there is provided a process for treating thick fine tailings (TFT), comprising: determining flocculant concentration of an in-line flow of a flocculant solution using near infrared (NIR) spectrometry; determining clay content of an in-line flow of the TFT; injecting the flocculant solution into the TFT at a flocculant dosage based on the clay content of the TFT and the flocculant concentration, to produce a flocculation material; dewatering the flocculation material to produce an aqueous stream and a solids-enriched material.

[0041] In some implementations, the process includes controlling the flocculant concentration in the flocculant solution using feedback control.

[0042] In some implementations, the process includes controlling the flocculant dosage in response to a change in the clay content, comprising: in response to an increase in the clay content: increasing the flocculant concentration in the flocculant solution, increasing a flowrate of the flocculant solution injected into the TFT, increasing a relative flowrate of the flocculant solution with respect to the TFT, and/or performing or increasing dilution of the TFT with an aqueous stream to reduce the clay content thereof; and in response to a decrease in the clay content: decreasing the flocculant concentration in the flocculant solution, decreasing a flowrate of the flocculant solution injected into the TFT, decreasing a relative flowrate of the flocculant solution with respect to the TFT, and/or decreasing or ceasing dilution of the TFT with an aqueous stream to reduce the clay content thereof.

[0043] In some implementations, determining the clay content of the in-line flow of the TFT is performed using NIR spectrometry. In some implementations, the NIR spectrometry comprises obtaining NIR spectral measurements on-line or at-line. In some implementations, the NIR spectral measurements are obtained using reflectance-type NIR spectroscopy. [0044] In some implementations, the process includes determining an NIR derived flocculant concentration from the NIR spectral measurements in accordance with a predetermined chemometric model correlating NIR spectral measurements and actual flocculant concentration in flocculant solution samples; and controlling injection of the flocculant solution based on the NIR derived flocculant concentration. In some implementations, the flocculant concentration and the clay content of the TFT flow are continuously determined; and the flocculant dosage is continuously adjusted based on the flocculant concentration and the clay content.

[0045] In some implementations, there is provided a process for treating thick fine tailings (TFT), comprising: injecting a flocculant into a TFT flow to produce a flocculation material; obtaining near infrared (NIR) spectral measurements of the flocculation material using NIR spectroscopy, to provide an NIR derived dewatering parameter; dewatering the flocculation material to produce an aqueous stream and a dewatered solids-enriched material; and controlling a process operating condition based on the NIR derived dewatering parameter using feedback control.

[0046] In some implementations, the controlling comprises adjusting injection of the flocculant into the TFT flow as the process operating condition, in response to a change in the dewatering parameter. In some implementations, the controlling comprises adjusting dilution of the TFT flow prior to injection of the flocculant as the process operating condition, in response to a change in the dewatering parameter. In some implementations, the controlling comprises adjusting clay content of the TFT flow prior to injection of the flocculant as the process operating condition, in response to a change in the dewatering parameter.

[0047] In some implementations, the dewatering parameter comprises Net Water Release (NWR) determined after a NWR drainage time, wherein:

NWR = (quantity of water separated and recovered from the flocculation material - quantity of water added to TFT prior to flocculation including water from dilution and/or flocculant addition ) / (quantity of initial water in TFT prior to dilution and flocculant addition).

[0048] When the dilution fluid is water and the flocculant is added in the form or an aqueous solution, this added water is subtracted from the water release from the flocculated material. The NWR can thus take into account the total amount of water that may be added to the TFT prior to the dewatering step.

[0049] In some implementations, the NWR drainage time is between 20 minutes and 48 hours, between one hour and 36 hours or between 12 hours and 24 hours. In some implementations, the controlling comprises adjusting the process operating condition when the NWR falls below an NWR threshold. In some implementations, the NWR threshold is between 0.4 to 0.6 when the NWR drainage time is between 12 hours and 36 hours.

[0050] In addition, it should be noted that other dewatering parameters can be used. For example, instead of determining NWR after a given time period (e.g., 24 hours), the clay-to-water ratio (CWR) of the material can be measured after a given time period. The CWR can be determined as follows for the example time period of 24 hours after initiating dewatering:

CWR = (wt% solids in 24 hrs x % Clay)/(wt% water in 24hrs).

[0051] When CWR parameter is used, a minimum target can be set. For example, the minimum target for a 24 hours CWR can be 0.6, 0.65, or 0.7. It is also noted that the two terms NWR and CWR are related (NWR= 1-(Feed CWR/24hr CWR)).

[0052] In some implementations, the TFT is derived from an oil sands extraction operation.

[0053] In some implementations, the dewatering comprises subjecting the flocculation material to thickening in a thickener vessel and/or filtering by a filter device.

[0054] In some implementations, the dewatering comprises sub-aerial deposition. In some implementations, the sub-aerial deposition is performed onto a sloped deposition surface.

[0055] In some implementations, method for controlling polymer flocculant dosing into thick fine tailings (TFT), comprising: continuously obtaining near infrared (NIR) spectral measurements of the TFT using NIR spectroscopy, to provide an NIR derived clay content of the TFT; continuously obtaining NIR spectral measurements of a flocculant solution comprising the polymer flocculation using NIR spectroscopy, to provide an NIR derived flocculation concentration in the flocculant solution; and injecting the flocculant solution into the TFT to produce a flocculation material; and dosing the flocculant on a clay basis in accordance with the NIR derived flocculation concentration and the NIR derived clay content of the TFT.

[0056] In some implementations, the method includes diluting the TFT prior to injecting the flocculant solution to produce a diluted TFT. In some implementations, the NIR derived clay content in the TFT is obtained upstream of the diluting. In some implementations, the NIR derived clay content in the TFT is obtained for the diluted TFT downstream of the diluting. In some implementations, the diluting is controlled so that the diluted TFT has a clay-to-water ratio (CWR) between about 0.25 and about 0.33.

[0057] In some implementations, the TFT is derived from an oil sands extraction operation.

[0058] In some implementations, the method further includes dewatering the flocculation material. In some implementations, the dewatering comprises subjecting the flocculation material to thickening in a thickener vessel and/or filtering by a filter device. In some implementations, the dewatering comprises sub-aerial deposition onto a sloped deposition surface. In some implementations, each of the NIR spectral measurements is obtained using a reflectance-type NIR probe.

[0059] In some scenarios, the dewatering may include discharging the flocculated material into a location (e.g., a pit of a mine) to form a permanent aquatic storage structure.

[0060] Dilution of the TFT combined with NIR measurements to obtain clay content properties can enable advantages related to facilitating efficient flocculant dosage on a clay basis to achieve consistent dewatering performance. In addition, providing co- directional and centerline injection of the dilution fluid prior to flocculant injection can facilitate one or more of the following advantages: inhibiting plugging of the dilution injector outlets, enhancing mixing of the dilution fluid with the tailings by reducing segregation issues, and improving efficiency of downstream mixers. NIR measurements for obtaining NIR derived clay content in various TFT streams and/or flocculant concentration in the flocculant solution can also provide advantages, such as effective flocculant dosage on a clay basis, efficient flocculant usage, and enhanced performance of the dewatering process via feedback and/or feedforward control.

BRIEF DESCRIPTION OF DRAWINGS

[0061] Fig 1 is a flow diagram of an example thick fine tailings dewatering operation.

[0062] Fig 2 is a plan partial-transparent view schematic of an example dilution device fluidly connected to a pipeline.

[0063] Fig 3 is a plan partial-transparent view schematic of components of a dilution device.

[0064] Fig 4 is a cross-sectional view schematic of components of a dilution device.

[0065] Fig 5 is a plan view schematic of components of a dilution device.

[0066] Fig 6 is a plan view schematic of example components of a dilution device.

[0067] Fig 7 is a schematic of a pipeline configuration including a dilution device and downstream mixers.

[0068] Fig 8 is a flow diagram of an example thick fine tailings dewatering operation

[0069] Fig 9 is a graph of absorbance units versus wavelength number showing example NIR spectra of MFT.

[0070] Figs 10 to 17 are graphs of predicted values versus true values for various different component concentrations and variables (clay, fines, water, bitumen, MBI, etc.) in tailings.

[0071] Fig 18 is a graph of absorbance units versus wavelength number showing example NIR spectra of a mixture of MFT and polymer flocculant solution.

[0072] Fig 19 is a graph of predicted values versus true values for a dewatering parameter.

[0073] Fig 20 is a close up of a graph of predicted values versus true values illustrating correlation lines over different ranges of data points. DETAILED DESCRIPTION

[0074] The techniques described herein relate to the pre-treatment, monitoring, and handling of fluid materials in the context of dewatering thick fine tailings (TFT). In particular, enhancements described herein relate to the dilution of TFT prior to the addition of a flocculant solution, as well as the use of near infrared (NIR) techniques for determining properties of the TFT, the diluted TFT, the flocculant solution, and the flocculated material, which can be used for enhanced process control.

Overview of thick fine tailings dewatering operation

[0075] Referring to Fig 8, a thick fine tailings dewatering system 10 can include a thick fine tailings (TFT) source 12, such as a tailings pond, from which TFT is retrieved as an in-line TFT flow 14. The TFT flow 14 can then be supplied to one or more pre- treatment units 16 to produce a pretreated TFT stream 18. The pre-treatment units 16 can include various different units for screening, diluting, pre-shearing and/or chemically pre-treating the TFT. The pretreated TFT stream 18 is then supplied to a flocculant injection unit 20 for injecting a flocculant stream 22 into the tailings. Alternatively, there may be no pre-treatment units in some scenarios, and the thick fine tailings are supplied directly from the source to the flocculant injection step. The resulting flocculation material 24 can then be subjected to conditioning 26, which may include pipeline shear conditioning, to form a conditioned material 28. The conditioned material 28 is then sent to a dewatering unit 30, which may for example be a sub-aerial deposition area. Release water 32 separates from solid flocculated material and can be used a recycled water 34a, 34b for addition to certain pre-treatment units 16 (e.g., dilution unit) and/or to form part of the flocculant stream 22.

[0076] It should also be noted that the TFT source can be generated in various ways. In some scenarios, extraction tailings-that include course solids (e.g., sand), fine solids (e.g., clay), water and residual compounds-are supplied directly from an extraction facility to a tailings pond where the extraction tailings separate over time to form different layers in the pond, the fine unsettled layer being composed of thick fine tailings. In some other scenarios, extraction tailings can first be subjected to a separation step where coarse solids are removed and a thin fine tailings material is produced. The thin fine tailings, which has a relatively low solids concentration, is then supplied to a settling area or pond to allow settling and consolidation to form thick fine tailings material. The step of removing coarse mineral solids from the extraction tailings can also include removal of some of the fine solids as well. Examples of producing thick fine tailings and treating extraction tailings are described in Canadian patent No. 2,796,025. This patent describes, for example, a method that includes depositing extraction tailings to form a "sand dump" which facilitates removal of coarse solids and entrapment of some fine solids; collecting thin fine tailings next to the sand dump in a collection basin; and supplying a stream thin fine tailings from the collection basin to a maturation pond in order to generate thick fine tailings. Any of the techniques described in patent No. 2,796,025 can be used to generate thick fine tailings that are then processed using techniques described herein.

[0077] Fig 8 also illustrates that various process streams can be monitored using measurement devices M. Such measurement devices M can measure process parameters, such as composition, flow rates, rheological properties, temperature, and so on. The data from the measurement devices M can then be used to control process unit operations. For example, flocculant dosage is a relevant parameter for enabling consistent and efficient performance of the flocculation and dewatering of the TFT. Process parameters, such as flocculant concentration in the flocculant stream 22 and the composition of the pretreated TFT stream 18, are relevant to flocculant dosage and thus can be measured and used to inform the flocculant dosage.

[0078] It should be noted that other types of dewatering chemicals can be used instead of or in addition to the flocculant. In addition, while the units illustrated in Fig 1 may be provided as part of an in-line pipe-based system in which the materials are transported and treated in a continuous manner along a pipeline prior to being deposited, in some implementations it is possible to use units that are not in-line pipe- based but are rather tank-based, for example, to perform certain process steps. In some implementations, the flocculant comprises an anionic polymer flocculant, which may be a sodium salt of an anionic polymer, such as a 30% anionic sodium polyacrylamide- polyacrylate co-polymer. The polymer flocculant may also have a desired high molecular weight, for instance over 10,000,000, for certain flocculation reactivity and dewatering potential. The polymer flocculant may be generally linear or not according to the desired shear and process response and reactivity with the given TFT. [0079] It should further be noted that various features, step and implementations described above may be combined with other features, step and implementations described above or herein. For example, one or more pre-treatment methods may be selected in accordance with given TFT properties. For instance, in the case where the TFT to be treated has higher bitumen content (e.g., higher than 5 wt.%) a bitumen removal step may be included, whereas in the case that the thick fine tailings to be treated has a bitumen content lower than 5 wt.% one may opt not to implement a bitumen removal step. Likewise, in the case where the TFT to be treated has an initial low yield strength (e.g., lower than 5 to 15 Pa) and/or low clay content, a pre-shearing step or dilution may not be performed. In some scenarios, the TFT to be treated may have one or more features where certain selected pre-treatment(s) would be beneficial, and thus may be selected based upon an initial analysis of the thick fine tailings.

[0080] Dewatering techniques can be influenced by various properties of the TFT being treated. Some of the properties that can influence the process are yield stress, viscosity, clay-to-water ratio (CWR), sand-to-fines ratio (SFR), clay content, bitumen content, salt content, and various other chemical and rheological properties. Various additional methods and steps may be combined to improve the dewatering operation in accordance with certain properties of the TFT.

[0081] It is also noted that the flocculant injection unit can have various designs, such as an in-line co-annular injector or other types of injectors that rapidly disperse the flocculant solution into the TFT. In addition, the downstream handling of the flocculation material can include pipelining and expelling into a deposition area for dewatering. The pipelining can be managed according to various techniques that have been previously described, e.g., where the flocculation material is subject to sufficient in-line shear to be within a water-release zone upon deposition. The water-release zone can be where the flocculated material has passed a peak yield stress but is not over-sheared, such that the water-release characteristics of the material are in a maximum region. The design and operation of the pipeline can be conducted according to the Camp Number, for example. It is noted that other downstream handling equipment can be used to handle the flocculation material in between flocculation and dewatering.

[0082] It is also noted that the dewatering step can be performed using various techniques. In some implementations, the dewatering includes depositing the flocculated material onto a sub-aerial deposition area in relatively thin "lifts" (e.g., approximately 20 to 30 centimeters) where each lift is allowed to dewater and dry by drainage and evaporation before a subsequent lift is deposited on the dewatered lift. In some implementations, the flocculated material can be discharged into a holding structure (e.g., a mine pit) where it fills the volume and eventually forms a permanent aquatic storage structure with solids at the bottom and water on top. Other dewatering techniques can include supplying the flocculated material to a dewatering device (e.g., gravity thickener, centrifugal separation device) which produces a solids-depleted water fraction and a solids-enriched water-depleted fraction that can be deposited sub-aerially.

Dilution pre-treatment implementations

[0083] Referring to Fig 1 , a dilution unit 36 can be used to pre-treat the TFT by adding an aqueous dilution stream 38. The dilution can be controlled in order to obtain a diluted TFT stream 40 having a clay-to-water ratio (CWR) within a CWR range facilitating the flocculation and dewatering of the TFT, for example by enhanced control of flocculant dosage on a clay basis. In some implementations, the CWR of the diluted TFT stream 40 may be in between 0.25 and 0.33.

[0084] Still referring to Fig 1 , the diluted TFT stream 40 can be subjected to homogenization 42 which may be accomplished by passing through mixing devices in order to thoroughly mix the added dilution fluid into the TFT. The resulting pretreated TFT stream 18 can then be supplied to the flocculant injection unit 20.

[0085] Referring to Fig 2, in some implementations the dilution unit 36 includes various features that can be used in particular for in-line systems. The dilution unit 36 can include a main pipe conduit 39 that receives the TFT flow 14, and a diluting injector quill 41 extending into the main pipe conduit 39 and having an dilution outlet 43 that is sized and positioned within the main pipe conduit 39 such that the dilution fluid is injected co-directionally within the TFT flow 14 to form a dilution component flow that is surrounded by TFT material. In other words, the dilution fluid is injected co-directionally into a middle region of the TFT flow away from internal walls of the main pipe conduit 39. In some implementations, the dilution outlet 43 is positioned at a cross-sectional center- point 44 of the main pipe conduit 39. The dilution outlet 43 can also be positioned at a determined distance away from the surrounding side walls of the main pipe conduit 39, in order to prevent the dilution stream from contacting the side walls prior to homogenization 42. The dilution outlet 43 can also be designed to have a shape that limits the formation of an outward cone-like spray of the dilution liquid that would impinge on the side walls.

[0086] It should be understood that "co-directional" means that the dilution fluid is injected in the same general direction as the flow of TFT so that the injected dilution fluid remains within the bulk flow of the tailings rather than forming a segregated flow against the side pipe walls. Thus, co-directional injection does not require that the outlet of the dilution unit be oriented to expel the dilution fluid precisely parallel to the longitudinal axis of the pipe, but rather that the dilution fluid have a velocity component in the downstream direction sufficient to be carried with and mix into the bulk of the TFT flow. In other words, the dilution fluid can be injected at various angles relative to the longitudinal axis of the pipe, but should have sufficient forward momentum to avoid substantial segregation that would lead to stratified flow along the pipe walls. As per the description of various implementations of the dilution unit, the dilution fluid can be injected at certain angles relative to the longitudinal axis of the pipe or parallel therewith.

[0087] As illustrated in Fig 2, the dilution unit 36 can include additional features, such as a bypass line 46 coupled to the pipeline so as to bypass a portion or all of the incoming TFT flow 14 past the diluting injector quill 41 , which may be useful when the TFT material already has the desired properties. Appropriate valves or gates 48 (e.g., knife gates) can be provided on the bypass line 46 and the other pipeline components around the main pipe conduit 39 in order to operate the bypass.

[0088] The piping and equipment of the dilution unit 36 can include various elbows 50, Y-laterals 52, flanges 54, pipe sections 56, drains, reducers, and so on. The dilution unit 36 can be adapted to fluidly connect to an existing pipeline 60a, 60b.

[0089] Still referring to Fig 2, there can be more that one dilution injector quill 40 for providing the dilution fluid. In some implementations, there are at least a first injector quill and a second injector quill that are located in spaced-apart relation along a length of the main pipe conduit 39. In some implementations, the injector quills are configured to receive and inject at different flow rates in order to provide different levels of dilution. For example, one dilution quill may have a smaller feed pipe section 62 and smaller dilution outlet 43 for diluting at lower rates compared to a larger dilution quill. Such high-rate and low-rate dilution quills can be operated alternatively, i.e., only one is operated at a time depending on the dilution targets for a given incoming TFT. In other scenarios, dilution quills can be operated simultaneously, if desired. The multiple dilution quills can be supplied with dilution fluid via a single dilution fluid header 64.

[0090] Referring now to Figs 2 and 3, the injector quills 40 can each be configured such that the feed pipe section 62 is at an oblique angle β relative to the main pipe conduit 39, and the dilution outlet 43 is formed by providing an oblique cut through the pipe (also referred to as a biased-cut nozzle). The oblique angle may be, for example, between 60° and 30° (e.g. 45°). Such constructions are easy and low-cost, while promoting the co-directional and center-line injection of the dilution liquid. It should nevertheless be noted that other injector quill configurations can be used, which may include a nozzle 66 as illustrated in Fig 6.

[0091] Referring to Fig 3, the dilution unit 36 includes equipment for cooperation of the injector quills 40 and the main pipe conduit 39, such as openings in the main pipe conduit 39 by which the feed pipe sections 62 enter, as well as associated attachment elements such as pads 68 that may each have a weeping hole 70 and upstream and downstream sides 72, 74 abutting on the feed pipe sections 62.

[0092] Referring briefly to Fig 6, it should be noted that the injector quills 40 can have various constructions and configurations, which can be provided to achieve the co- directional and center-line injection of the dilution fluid. In some implementations, the injector quill 40 may have an elbow-type nozzle 66 that is oriented and positioned to point along the central longitudinal axis of the main pipe conduit 39. The outlet 42 of the injector quill 40 can be the same or similar diameter as the upstream pipe section 62, or the outlet can be tapered as illustrated in the elbow-type nozzle 66 embodiment of Fig 6.

[0093] In some implementations, the dilution unit 36 has a "Tee" configuration, examples of which are generally illustrated in Figs 4 and 5. Due to lower maintenance and ease of operation, a Tee joint can be used. The mixing performance of a Tee joint has been found effective particularly with certain conditions. First, the approaching flow to the Tee joint should be fully turbulent to promote effective mixing. Second, it has been found that the pipe diameters are a strong function of the ratio of the flow rates for both the streams (Equation 1): q / Q = (d/ D) 1.5 (Equation 1) where q and Q are flow rates of the side and main streams respectively. Similarly, d and D represent the side and main stream pipe diameters.

[0094] The mixing mechanism of a Tee joint can be divided into two parts. The first part where most of the mixing occurs is known as the initial mixing zone. The length of the initial mixing zone is relatively small and depends upon the ratio of momenta of the two streams. To maximize mixing in this zone, the jet of dilution fluid should get the maximum exposure to the approaching thick fine tailings flow. In other words, the jet should not prematurely bend to the side wall adjacent to the Tee inlet. In situations where the side stream is injected with very high momentum, the jet may strike the opposite wall, and unfortunately the understanding of mixing performance in such situations is not well established in the literature. Hence for optimum mixing, the jet should generally align to the centerline of the main pipe section 39, and be designed as per the correlation presented above.

[0095] Since the ratio of TFT and dilution water flow rates will depend upon the CWR of the TFT feed, the ideal ratio of the pipe diameters will also change for each CWR. To promote good mixing performance within practical measures, multiple sequential Tee joints can be provided. In some implementations, referring to Fig 5, three sequential Tee junctions are provided, each with different branch diameters (d3, d2, di) suitable for low, mid and high CWR (0.35, 0.43, and 0.48) feeds respectively. Furthermore, it has been found that the addition of the side stream through multiple side branches provides improved mixing over the single side inlet. In some implementations, each side stream can be split in to multiple side streams of equal diameters (e.g., four streams of equal diameters oriented at 90° to each other, as illustrated in Fig 4). The multiple inlets also encourage the dilution fluid jets to align on the centerline of the main pipe, thus promoting effective mixing.

[0096] Referring now to Fig 7, the homogenization unit 40 downstream from the dilution unit 36 can include multiple mixers 76 arranged in series. Fig 7 also illustrates that the dilution unit 36 can be incorporated within a pipeline system that includes an upstream supply pipeline 78 (with a diameter Di) and an upstream feed pipe (with diameter D2), where D2 may be smaller than Di to facilitate providing desired turbulence or flow rate conditions. In addition, there may be a downstream pipe section 82 in fluid communication with the dilution unit 36 to provide the diluted TFT 40 to the first mixer 76. The mixers 76 may be static mixers that are provided in-line. The mixers 76 may be followed by a second downstream pipe section 84, followed by a downstream supply pipeline 86 that supplies the pretreated TFT to the flocculant injection unit 20. The piping and equipment downstream of the dilution unit 36 may be configured to fully mix the dilution fluid with the TFT. The pipe lengths , L2 and L3 as well as the number and design of the mixers 76 can be adjusted accordingly. In some implementations, there can be at least eight static mixers 76, at least ten static mixers, or between eight and sixteen static mixers arranged in series.

[0097] In some implementations, the homogenization is performed without the use of downstream static mixers. For example, the homogenization can be performed by shear imparted from the pipeline flow in combination with one or more pumps that are located in between the dilution and the flocculation. Shear provided by pipe walls and pump can be sufficient for attaining certain target mixing levels (e.g. , 0.05 CoV or below) prior to flocculation. In addition, centerline injection of the dilution fluid can facilitate such homogenization techniques by inhibiting segregation of the dilution fluid from the tailings. When the dilution fluid is water with a specific gravity of 1 and the TFT have a clay or solids content that increases the density to about 1.2 or 1.3, for example, the tendency of the fluids being segregated can be significant. Thus, by providing the co-directional and centerline injection the dilution fluid can avoid contacting the side pipe walls as a segregated flow and can be pre-mixed with the tailings prior to a downstream pump or static mixer which can complete the homogenization prior to flocculation. For thicker TFT materials, the tendency for stratified flow can be greater, and thus the benefit of centerline injection can also increase.

[0098] Co-directional and centerline water injection followed by homogenization facilitates providing a well-mixed, non-stratified diluted TFT flow that can be effectively flocculated and subsequently dewatered. Simple addition of water to a TFT flow without mixing can result in a stratified flow which, in turn, can reduce the efficiency of the flocculation stage. Dilution can not only aid in providing a consistent CWR of the TFT flow to facilitate accurate flocculant dosing, but can also enhance flocculant usage due to improved in-line mixing of the flocculant with a well-mixed diluted TFT flow.

[0099] Providing co-directional and centerline injection of the dilution fluid can facilitate various advantages, such as inhibiting plugging of the injector outlets, reducing segregation issues, and enhancing efficient operation of downstream mixers when present. For instance, providing the dilution fluid near the centerline of the TFT flow so that the dilution fluid is still surrounded by TFT material as the stream engages the downstream mixers, enables more efficient mixing. For example, if the dilution fluid contacts the pipe wall, then there can be increased risk of segregation resulting in lower mixing efficiency, performance, reliability, and/or adaptability to changes in flow rates. In some implementations, the centreline water injection for the injectors promotes mixing between the TFT flow 18 and the dilution water 38 prior to the downstream static mixers 76 where the bulk of the mixing occurs.

[00100] In addition, multiple water inlets, as illustrated in Figs 2, 3 and 5, can provide advantages, including facilitating the control of dilution water flowrates at higher and lower dilution water requirements. For example, when the incoming TFT flow has a lower CWR and thus lower dilution is indicated, the dilution unit can be operated by injecting water via only one of the water inlets which may be selected to be the smaller feed pipe section designed for providing lower flowrates. When the incoming TFT flow has a higher CWR and thus higher dilution is indicated, the dilution unit 36 can be operated by injecting water via the larger feed pipe section designed for providing higher flowrates. The different water inlets or feed pipe sections can be designed with a flowrate capacity sufficiently large that sufficient water can be supplied for a maximum CWR that may be encountered to enable a certain target diluted CWR level. The multiple feed pipe sections can also be equipped with valves or other devices so that one or more can be controlled to vary the water flowrate. The CWR of the TFT and its flowrate can change significantly depending on a number of factors (e.g., retrieval site of the TFT, depth of TFT in pond, composition of the TFT, pre-treatment of TFT, upstream operations in the dewatering process, etc.). The dilution unit can have multiple water inlets to facilitate control of the dilution water flowrate at both high and low range flows, optionally with only one water inlet operating at a time. [00101] In some implementations, the dilution unit can be controlled in order to obtain a target CWR value within the CWR range (e.g., about 0.25 to about 0.33). The CWR range can be determined based on a number of factors, such as the composition of the TFTs to treat, the polymer flocculant to be used, additional chemicals or pre-treatments to be implemented, the design and operation of the flocculant injector and the dilution unit, and the mixing characteristics in the system. The CWR range can be determined using empirical testing and/or modelling. For instance, TFT samples having different CWRs can be tested by subjecting the samples to flocculation and dewatering conditions to determine a preferred CWR range in which maximum dewatering occurs, e.g., a preferred Net-Water-Release (NWR) from the flocculated material. Studies have determined that NWR and CWR can be correlated, and thus the CWR range can be determined or defined in to obtain a desired NWR for the process design criteria. Empirical testing can include multiple runs using different polymer flocculants and other variables that may influence the NWR (or another dewatering parameter) in order to determine a CWR range. Once the CWR range is determined, the dilution can be designed and operated to achieve target CWR values for the TFT flow prior to flocculation.

[00102] In addition, the dilution control can be coordinated with measurements, such as NIR based readings, providing data that is correlated with compositional properties related to clay content (e.g., clay wt% per total weight of fluid, CWR, etc.). In some implementations, dilution control includes regulating or varying the flowrate of the dilution fluid, which may be done by manipulating a valve or orifice incorporated into the feed pipe section(s) of the dilution unit, by varying a pump that supplies the dilution fluid, by controlling the number of dilution inlets that are open, by varying the relative flowrates between the TFT flow and the dilution fluid, and/or by various other methods.

[00103] The dilution fluid can be an aqueous stream substantially composed of water, which may include or consist of fresh water, process effluent water (e.g., from an extraction process from which the TFT was derived), and/or other water sources. The dilution fluid may include little or no clay or other suspended solid materials. For example, dilution water may be taken from oil sands or other mining operations, and/or may be recycled from the dewatering operation itself as part of the release water. In some implementations, the dilution may be carried out by combining a higher water content tailings stream into to a TFT stream. In the event that the dilution fluid includes clay, an additional measurement probe (e.g., NIR probe) may be incorporated for measuring the clay content of the dilution fluid, and that reading can be incorporated into the overall determination of the diluted TFT clay content for flocculant dosing and process control purposes. It should be noted that while NIR based methods are described herein in detail, various other measurement and control techniques could be used in connection with the dilution methods (e.g., a density meter could be used).

[00104] In some implementations, the TFT exhibits non-Newtonian rheology, and the dilution followed by homogenization enable the pre-treated TFT to be closer to Newtonian behaviour.

[00105] In some implementations, the homogenization of the diluted thick fine tailings is performed to achieve a least a certain level of mixing, which may be defined in a number of ways, e.g., by coefficient of variation (CoV). For example, the homogenization can be done to produce a mixture having at least a target mixing level, such as a CoV of at most 0.05, at most 0.04, at most 0.03 or at most 0.02. The target CoV range can be 0.05 to 0.01 , which have been studied using modelling techniques and it has been found that this range provides desirable performance. Higher CoV values can also be possible, and can be verified by modelling, small scale testing, or other techniques. Other mixing parameters can also be used for process design and/or process control. The homogenization level can be influence or controlled by a number of variables, such as flow rate, mixer type and number, pipe diameter and length, flow regime (e.g., turbulence, Reynolds Number), or other pipeline features that impart shear and/or enable turbulence. The mixers may be in-line static mixers, tank mixers, or a combination thereof. The mixers may be monitored and controlled to impart a controlled and pre-determined amount of mixing energy to the diluted tailings, or the mixers can simply be provided without any active or ongoing control.

[00106] Referring to Fig 1 , in some implementations, one or more control units 86 can be provided to receive data and to control a process variable, such as the dilution flow 38. Fig 1 illustrates that there may be various measurement devices, e.g., NIR sensors (A) to (D), that are arranged at different points in the system, and there may be associated control units 86 (A) to (D) that are configured for receiving the measured data from the measurement devices and controlling one or more process variables based on the data. For example, measurements of CWR or clay content from the TFT flow 14 can be used control dilution fluid 38 via control unit (A), and measurements of CWR or clay content from the diluted and well-mixed TFT flow 18 can be used control flocculant 22 input via control unit (B). Other control units can be located at different points in the system to control process variables, such as flowrates, which can impact the dewatering process.

[00107] Control unit (A) can be configured to control the dilution unit (e.g., the different injector quills) to provide sufficient dilution fluid to obtain a target CWR value for the diluted TFT flow 40 depending on the clay content of the incoming TFT flow 14. Control unit (A) can thus enable feedforward control for the dilution, although it can also be configured for feedback control of upstream operations such as dredging or other TFT retrieval activities.

[00108] Control unit (B) can be configured to control the flocculant solution flowrate to provide a target flocculant dosage based on the clay content of the incoming diluted TFT flow 18, as clay-based dosage can facilitate enhanced flocculant dosing and usage. Control unit (B) can thus enable feedforward control for the dilution, although it may also be configured for feedback control of the dilution.

[00109] Control unit (C) can be configured to control flocculant solution preparation, including the operation of a polymer make-down unit (PMU), the flocculant content of the flocculant solution (e.g., wt% of the polymer flocculant in the solution), and the chemistry of the flocculant solution (e.g., due to the water used for the flocculant solution, which may include process water, make-up water, fresh water, and/or distilled or purified water). Control unit (C) can operate based on measured properties of the flocculant solution 22 (e.g., measured flocculant content) that is supplied to the flocculation injection step 20. Control unit (C) can thus enable feedback control for flocculation solution preparation.

[001 10] Control unit (D) can be configured to control various parts of the process based on measured data regarding the flocculated material (e.g., yield stress, water release characteristics, rheological properties, etc.). Control unit (D) can, for example, be coupled to other control units (A), (B) and/or (C) so that upstream process variables can be controlled or adjusted based on downstream flocculated material properties. Control unit (D) can thus enable feedback control for various aspects of the process. [001 11] The measurement devices M can be configured and operated to obtain one or more relevant data type regarding a process stream or unit operation of interest. In some implementations, the measurement devices include NIR based sensors. More regarding NIR based measurements and clay content determination is discussed further below.

[001 12] In some implementations, the NI R probe(s) can be angled and positioned within the pipeline(s) in certain ways according to the various streams to be measured. For instance, in homogeneous process streams the N I R probes may be positioned at various angles and locations within the pipe. In non-homogeneous streams, such as N I RD, it may be advantageous to locate the probe closer to the center of the pipe and identify one or more angle of immersion to obtain the best representative scan of the stream for compositional analyses. In addition, for segregated streams that have distinct layers of different fluid compositions, it may be desired to locate multiple N I R probes at a same location along a pipe length but at different positions within the pipe (e.g., upper and lower regions) for obtaining measurements regarding the two distinct fluid layers.

[001 13] While NIR probes can be advantageously used to determine various characteristics of process streams, it should also be noted that alternative methods can be used. For example, when determining clay content of the TFT stream prior to or after dilution, it is possible to use other techniques, such as methylene blue index (MBI) methods. Various MBI methodologies can be implemented.

NIR spectrometry and process control implementations

[001 14] Referring to Fig 1 , various NI R based measurement and monitoring techniques can be implemented in connection with the flocculation and dewatering operation. For example, a first NI R probe (N I RA) can be provided to determine clay content of the TFT flow 14, which can be used to control or vary operation of the dilution 36 (e.g., control the flowrate of dilution added to the TFT, and the operation of the dilution unit). A second N I R probe (N I RB) can be provided to determine clay content of the diluted TFT flow 18 after the homogenization 42, which can be used to control or vary operation of the flocculation step 36 (e.g., control the flowrate of the flocculant solution 22 added to the diluted TFT 18). A third N I R probe (N I R_C) can be provided to determine polymer flocculant concentration of the flocculant solution 22 prior to addition into the diluted TFT 18. A fourth N I R probe (N I RD) can be provided to determine characteristics of the flocculated material. For example, an N I R probe located at N I RD can identify whether segregation of the flocculated material into a water fraction and a solids-enriched fraction is occurring.

[001 15] It should be noted that the various N I R probes can be used to obtain N I R spectral data that can be used to determine a number of compositional properties of the process streams. Thus, for example, the N I R probe at N I RA can obtain data that is used to determine not only clay content for dilution control, but also bitumen content to determine whether a bitumen pre-treatment step should be implemented or whether the downstream process should be otherwise adapted to higher bitumen content. In addition, other N I R probes and associated controllers not shown in Fig 1 can also be provided to monitor and control the process. The N I R probes and associated controllers can be automated to provide continuous data acquisition and control, or can be manual or semi-manual to provide more periodic data acquisition and control.

[001 16] In some implementations, the overall dewatering process includes multiple N I R sensor locations generally corresponding to N I RA, N I RB, N I RC and N I RD. The N I R based measurements facilitate optimizing polymer flocculant addition based on the TFT feed composition to maximize water separation and production of treated, dewatered material. On-line or at-line N I R measurements can facilitate rapid data acquisition of process variables that are relevant to flocculant dosage, and thus avoid delays related to laboratory-based sampling and measurement techniques.

[001 17] In some implementations, NIR probes are used to obtain clay content and flocculant content data. The NIR probes can be installed on-line. Transmission-type NIR probes and/or reflectance-type NIR probes can be used. It was found that reflectance- type NIR probes (e.g., Albedo™ probe) facilitate reduced fouling of the probes. The NIR probes can be used on-line, where the probes are physically integrated into the tailings treatment pipeline. The NIR probes can also be used at-line, where the probes are portable but are used at certain locations of the pipeline to take measurements rather than taking a sample and performing the measurement at another location (e.g., laboratory). The NIR probes can be used in conjunction with slipstreams taken off of certain process streams, either on-line or at-line, if desired. [001 18] In existing methods using NIR spectrometry for oil sands materials, the component of interest has typically been bitumen. However, according to implementations described herein, NIR spectrometry is used to determine clay related properties of a TFT stream. Existing methods for measuring or estimating clay content, such as methylene blue index (MBI), have the challenge of being off-line techniques. In addition, clay content on a solids basis can vary widely in slurry streams, for example from 10 wt% to 100 wt% (or above 100% when MBI are used), and the variability of clay content can cause challenges in terms of fluid rheology, mixing, and flocculant dosing. Thus, accurate and real-time clay content measurements, which are facilitated by NIR spectrometry, can have a number of advantages in the context of flocculation and dewatering of slurry streams, such as TFT. Accurate clay content measurements are also relatively complex and time consuming, and thus an NIR-based correlation enables real-time NIR measurements that have been correlated to accurate information to leverage the painstaking baseline measurements.

[001 19] In some implementations, the NIR probe is provided on-line or at-line at a location along the pipeline in which the pipe is full of tailings slurry. Locating and operating the NIR probes may therefore be done in conjunction with where the slurry completely fills the pipe. For example, at certain operating conditions of lower flowrates, a given pipe section having a larger diameter may not be completely full while other pipe sections having smaller diameters will remain full. The NIR probes can be used at such slurry-filled locations of the pipeline for improved data collection. In addition, certain flow control devices may be installed and operated in order to ensure that a given NIR measurement location of a pipeline is full during NIR measurement collection.

[00120] In some operations that retrieve tailings (e.g., MFT) from existing ponds, a density-meter has been used to determine in-pond density in order to then estimate clay content based on density-clay correlations. However, this methodology may have challenges with respect to new ponds or ponds that display different settling and mixing characteristics. Instead of using density as a correlated proxy for clay content, NIR based techniques described herein can enable rapid determination of clay content for flocculant dosage.

[00121] Existing flocculant injectors that have a particular design and construction can be used in an optimal fashion within a pre-determined range of CWR, which influences the rheology and mixing as well as the clay-basis flocculant dose. The NIR and dilution techniques described herein facilitate achieving accurate CWR levels within the optimal CWR range. The target CWR can be achieved by diluting the TFT with water, where the target CWR can be pre-determined based on a number of factors, such as the flocculant injector design, the composition of the TFT, and the nature of the polymer flocculant to be used. The target CWR may be determined based in part on existing infrastructure and equipment of a TFT dewatering system, to enhance operation of the system. In some scenarios, the NIR probes for determining clay content of the TFT can be used to determine the CWR after the TFT screens that remove coarse solids debris and before the dilution unit. Thus, the NIR based measurement techniques for determining clay content combined with dilution of the TFT prior to flocculation can facilitate enhanced flocculant injection and dosing on a clay basis.

[00122] In some implementations, statistical process control (SPC) can be used. For example, online NIR scans (e.g., at 1 -minute frequency or faster) can provide several thousand data points at each scan. SPC can be used for the detection of process abnormalities based on changes to the statistical properties of the NIR scan data. Multiple scan data can be taken from "normal operation" (which can be called "training data"), and statistical limits can then be defined for the data. Subsequently, the statistical properties of each NIR scan can be compared with these pre-determined statistical limits. If there are sustained deviations or excursions, the process may be identified as "abnormal" compared with the training data. In the context of flocculation and dewatering of thick fine tailings, "abnormal" operation can mean that the quality of additives has changed, that there are unknown components in the stream, or that the process itself has changed due to damage to the internal components that the operators are not aware of. When the SPC chart shows abnormality, the corrective action may be automated or non-automated. For example, further investigation may be needed to bring the process back to normal; or the so-called "abnormality" may be accepted and it may be added to the "training data" in order to recalculate the statistical limits. SPC can help in detecting the subtle changes in the process or a given process stream in real time.

Thick fine tailings and other tailings streams

[00123] As noted above, TFT material mainly includes water and fine mineral solids, where the solids content and the fines portion are sufficiently high such that the fines tend to remain in suspension in the water and the material has slow consolidation rates. More particularly, the TFT may have a ratio of coarse particles to the fines that is less than or equal to one. The TFT can have a fines content sufficiently high such that flocculation of the fines and conditioning of the flocculated material can achieve a two phase material where release water can flow through and away from the floes. For example, TFT may have a solids content between 10 wt.% and 45 wt.% (or between 15 wt% and 40 wt%, or between 20 wt% and 35 wt%), and a fines content of at least 50 wt.% on a total solids basis (or at least 55 wt.%, 60 wt%, 65 wt%, 70 wt%, 75 wt%, 80 wt%, 85 wt%, 90 wt%, 95 wt% or 99 wt% on a total solids basis), giving the material a relatively low sand or coarse solids content. The TFT may be retrieved from a tailings pond or another source. While TFT is typically formed by gravity settling in a pond or other structure, it should also be noted that TFT material can also be formed using other separation devices.

[00124] As also mentioned above, TFT dewatering techniques may include various steps for pre-treating the thick fine tailings, chemically modifying the thick fine tailings by addition of a dewatering chemical such as a polymer flocculant, as well as monitoring or managing physical and chemical properties of the thick fine tailings.

[00125] In the context of oil sands, for example, tailings may include fine and coarse mineral particles, water and residual bitumen. Tailings may be stored in large reservoirs called tailings ponds. The TFT supply arrangement and methodology may be provided in accordance with the properties of the TFT to be treated by the dewatering operation. For example, dredges, barges, submersible pumps, pipe layouts and pre-treatment units may be provided and operated based on thick fine tailings properties. The dredges or submersible pumps that may be used in the case of treating tailings withdrawn from a tailings pond may be operated to retrieve the TFT from a certain depth or location to obtain thick fine tailings within desired property ranges, such as clay-to-water ratio (CWR), sand-to-fines ratio (SFR), and/or bitumen content ranges.

[00126] It should also be noted that certain aspects of the dewatering techniques described herein may be adapted for different types of TFT. For example, the structure, properties and dosage range of the dewatering chemical, such as a polymer flocculant, may be modified and provided depending affinities with the particular type of thick fine tailings. In addition, certain pre-treatment steps may be performed for thick fine tailings having certain properties and compositions. For example, thick fine tailings containing quantities of hydrocarbons, e.g., heavy hydrocarbons such as bitumen, which would interfere with flocculation, may be subjected to an initial hydrocarbon removal step below a threshold concentration. In another example, thick fine tailings having a relatively high static yield stress, for example due to having a composition with a relatively high fines content and density, may be subjected to a pre-shear thinning or dilution treatment prior to addition of the dewatering chemical.

[00127] In general, TFT will have properties depending on its processing history and the nature of the mined ore from which it was derived. While water and fine solids are the main components of TFT, there may be various other compounds and materials present in the TFT depending on its origin and upstream processing history. It is also noted that the TFT material that is supplied to the flocculation and dewatering operation may be variable in terms of one or more properties (flow rate, chemistry, composition, etc.) such that monitoring and process control can be adapted to the variable TFT feed stream.

[00128] In addition, other tailings streams can be subjected to certain treatments and analyses that are disclosed herein. For example, the dilution device and associated methodologies can be implemented for tailings streams other than TFT in order to obtain desired dilution effects for such tailings streams, which may be desirable prior to a subsequent treatment (e.g., a chemical treatment, such as flocculation, or a physical treatment). In particular, tailings streams that can benefit from NIR analyses, CWR measurements and/or dilution can be used in connection with techniques described herein. Such NIR analyses, CWR measurements and/or dilution of various tailings streams can be done in the context of enhancing chemical treatment the tailings stream, for example by using clay based dosage of a chemical. For instance, depending on the composition of the tailings stream and the nature of the downstream treatment of the tailings stream, the NIR based methods can be adapted to monitor certain relevant properties. It should also be noted that the downstream treatment (e.g., flocculation) can be adapted depending on the composition of the tailings stream.

[00129] The following are examples of tailings streams that may be diluted, monitored and/or otherwise treated using various techniques described herein: whole tailings, froth treatment tailings, thin fine tailings, secondary/tertiary tailings, or blended/combined tailings. Whole tailings are produced from an extraction plant and include coarse mineral solids (e.g., sand) and fine mineral solids (e.g., clay) with a typical solids content of about 45 to 55 wt% although other compositions are possible. Froth treatment tailings are tailings from a froth treatment operation, typically derived from an underflow stream of a thickener or a tailings solvent recovery unit (TSRU). Thin fine tailings are relatively low solids content tailings (e.g., about 5 to 9 wt%) with a high fines content on a solids basis due to the coarser solids having been removed typically by settling. Thin fine tailings are often considered a precursor to TFT or MFT, since when left to settle thin fine tailings slowly increase in fines concentration to form TFT over a few years. Secondary and tertiary tailings are tailings that are derived from certain parts of an extraction operation.

[00130] Various blended or combined tailings materials can also be used in certain methods described herein. A blended tailings material includes tailings from multiple different sources, each source having a different composition. A blended tailings stream can be diluted using a substantially water based stream as the dilution fluid, or a first tailings stream can be diluted by adding a higher water content second tailings stream to thereby form a diluted blended tailings stream. For instance, a low clay content tailings (e.g., thin fine tailings) can be used as the dilution fluid that is injected into a higher clay content tailings (e.g., TFT), where NIR techniques can be used to analyse one or both of the tailings streams and/or the dilution device can be used for the injection. Such blending of multiple tailings streams can be controlled to achieve a desired composition of the diluted blended tailings stream to enhance downstream processing (e.g., flocculation or other chemical treatments). For example, NIR probes can be deployed for the input tailings streams and/or the diluted tailings stream and can be coupled to a controller in order to control the dilution to achieve the desired composition of the diluted tailings stream (e.g., the desired clay content).

[00131] It is also noted that tailings materials that are subjected to treatments and analyses as disclosed herein, can be retrieved from tailings disposal areas or can be supplied as tailings streams directly from a unit operation of an extraction plant (e.g., an underflow stream from a thickener, settling vessel, clarifier, centrifuge, etc.).

Additional implementations of NIR based monitoring and process control [00132] In some scenarios, NIR based monitoring techniques can be used in the context of various clay-containing oil sands slurry streams, such as hydrotransport slurry, primary extraction streams, secondary extraction streams, including various overflow, middlings and underflow streams. The clay-containing oil sands slurry stream can have an on-line or at-line NIR probe which obtains NIR spectral measurements, which are correlated to clay content properties to generate NIR derived clay content data for the given stream. The NIR derived clay content can then be used to control at least one upstream or downstream process operating condition. For example, extraction or mixing operations, which can be influenced by clay content, can be adjusted based on the NIR derived clay content. Thus, techniques described herein in relation to the dilution and flocculation of TFT streams can be adapted for use in other clay-containing oil sands slurry streams.

EXPERIMENTATION, MODELLING & RESULTS

[00133] NIR spectrometry has been studied in the context of thick fine tailings (TFT) flocculation and dewatering operations. Experimentation, chemometric modelling information, and other results are described below.

Reflectance and transmission NIR probes

[00134] Both reflectance and transmission NIR probes were tested in the context of obtaining NIR data. At location NIRc (see Fig 1), the transmission-type NIR probe experienced fouling which reduced the efficiency in this case. The reflectance-type NIR probe (Albedo™) was then used at NIRc for improved on-line NIR data collection for polymer flocculant concentration determination. The reflectance-type N I R probe was also used at N I RB for successful N I R data collection for clay content determination.

[00135] At locations N I RB and NIRc, the streams being analyzed are substantially homogeneous. On the other hand, at location N I RD the flocculated material may have undergone significant flocculation and in-line water release, making this stream relatively heterogeneous across a given cross-section of the pipeline. It is noted that the N I R spectrometry method and probe can be adapted depending on the data of interest, the composition of the stream, and the heterogeneity of the stream at the measurement point. For example, short or long N I R wavelengths can be selected depending on the desired application and the particular setup of the probe(s) at the given measurement location. Longer wavelengths can facilitate sampling of bulk material that may be heterogeneous, while shorter wavelengths can facilitate lower extinction coefficients and can permit longer path lengths to be used.

[00136] In some implementations, the NIR probe collects data and the region of interest of the spectra is from approximately 700 nanometers to 2,500 nanometers. The region of interest may not be a specific peak that is monitored within this range, but rather a combination of peaks that enable determination of characteristics or species of interest.

[00137] The NIR probe can use diffuse reflection (bundle) type of measurement and can be an immersion-type probe. In terms of optics characteristics, the NIR probe can include a 2m fiber bundle, with multiple (e.g., 14) fibers, NIR 400nm bis 2200nm, with 600 micron core. The illuminated spot diameter can be 5 mm.

Components or indicators for detection by NIR spectrometry and chemometric modelling

[00138] For NIRc, the main component of interest in the flocculant solution is the polymer flocculant for determination of concentration. Other components of the flocculant solution could also be measured, particularly when the aqueous component used to make the solution is process-affected water derived from extraction operations (e.g., tailings pond water, recycle water streams) and thus may contain dissolved or suspended compounds.

[00139] For TFT streams, there are a number of components that can be measured using NIR spectrometry, including bitumen or hydrocarbons, mineral solids, water, clay, fines, sands, methylene blue index (MBI), and so on. Fig 9 is a graph of absorbance units versus wavelength number showing a typical NIR spectra of MFT. MBI is one method for determining clay content of a sample, and depending on the particular MBI methodology that is used the MBI clay content can be above 100%. MBI is often used in the context of oil sands processing, and there may be significant amount of existing data based on MBI measurements. MBI of clays can thus be viewed as an indicator of clay content and can itself be determined by NIR in the context of the techniques described herein. [00140] Chemometric modelling was undertaken to develop correlations between the NIR spectral data and actual compositions of the TFT under study. Figs 10 to 17 are graphs illustrating predicted values versus true values for various different component concentrations, showing NIR chemometric model validations. Various other chemometric models have been developed for other variables, such as SFR and weight percent of certain components on a total solids basis.

[00141] Flocculated material was also subjected to NIR based testing. Fig 18 is a graph of absorbance units versus wavelength number showing an NIR spectra of MFT with polymer flocculant solution. Fig 19 illustrates a correlation with respect to the NWR from the flocculated material.

[00142] It was also found that there was a correlation between N I R spectra from flocculated MFT prior to dewatering and the NWR after 24 hours of dewatering, which indicates that NI R spectrometry can be used to measure the flocculated material prior to dewatering to predict dewatering performance as well as provide feedback to modify upstream operating conditions to enhance the process. Thus, referring to Fig 1 , for example, the process can include obtaining NI R data at location N I RD; based on the N I R data, determining an NI R-predicted dewatering parameter (e.g., NWR after a certain time period, such as 24 hours); and then adjusting the upstream process, as needed, to increase the dewatering parameter for the process. Thus, rather than waiting the full NWR drainage time period (e.g., 24 hours) in order to determine the dewatering performance, a real-time N I R measurement and correlation can be made to quickly predict general dewatering performance and make upstream adjustments to enhance the process.

[00143] It has also been found that chemometric modelling should be performed in a thorough and diligent manner in order to ensure that outlier data points are excluded and that the model is accurate over the relevant operating window. Fig 20 is an example pulled from modelling work for water content (wt% water), and illustrates that data points taken over too narrow a range gives an inaccurate correlation.

[00144] Tests have been also conducted on samples of oil sands MFT to assess flocculant dosage requirements. It has been found that dosing on a clay basis provides enhanced flocculation, dewatering and flocculate usage compared to dosing on a total mineral or total solids basis. It has also been found that clay based flocculant dosage can be performed over a CWR range of 0.23 to 0.44 to achieve the target dewatering performance for certain MFT samples and existing process equipment. Additional work has been conducted to develop a two-phase protocol to determine optimal flocculant dosages.

[00145] Additional studies sampling a TFT feed at intervals over several hours revealed that when feeding TFT from certain sources (e.g., ponds) most TFT properties can display little variance with the exception of the fines or clay content which have displayed some fluctuations for a single source. Blended TFT samples from different sources can display relatively consistent mineral content but significantly varying fines and clay content over the sampling periods. Therefore, when blending TFT streams from different sources, the clay content can monitored rather than approximating with mineral content for determining optimal flocculant dosage.

[00146] In the course of further testing, it has been determined that the clay content in TFT can be used for determining the optimal target set-point for polymer flocculant addition to the TFT, which reduces over- or under-dosage of the polymer flocculant that can result in reduced on-spec production of flocculated material. The clay content in TFT can also be used for accurate and real-time measurement of polymer flocculant concentration in the flocculation solution, which can help in maintaining the required concentration steady and consistent through closed-loop control. The clay content in TFT can also be used to maintain the specification of the TFT consistently in real-time for maximizing production of treated, solids-enriched, dewatered tailings material.

It should be noted that various implementations and aspects described herein can be combined with others that are described herein. For example, various pre-treatments steps can be combined with each other and with the steps of flocculant addition and dewatering. As another example, multiple NIR measurement points and process control strategies can be used in combination with each other for various parts of the overall process. It should also be noted that various apparatuses, systems and structures can be used to implement the methods described herein. In addition, methods described herein do not necessarily require that all of the steps be performed in the order illustrated or shown herein. Implementations and aspects of the techniques described herein are meant to be examples, and it should be understood that various alternatives and variants could also be used.

Claims

1. A process for dewatering mature fine tailings (MFT) derived from oil sands extraction, the process comprising: providing an in-line MFT flow; obtaining near infrared (NIR) spectral measurements of the MFT flow using NIR spectroscopy, to determine an NIR derived clay content of the MFT flow; diluting the in-line MFT flow with an aqueous stream based on the NIR derived clay content to produce a diluted MFT flow having a clay-to-water ratio (CWR) between about 0.25 and about 0.33; subjecting the diluted MFT flow to in-line homogenization in a series of in-line mixers to produce a pre-treated MFT flow; injecting an aqueous flocculant solution into the pre-treated MFT flow at a flocculant dosage based on the NIR derived clay content, to produce a flocculation material; and dewatering the flocculation material to produce an aqueous phase and a solids- enriched material.

2. The process of claim 1 , wherein the NIR spectral measurements are obtained on-line or at-line.

3. The process of claim 1 or 2, wherein the NIR spectral measurements are obtained using reflectance-type NIR spectroscopy.

4. The process of any one of claims 1 to 3, further comprising: determining the NIR derived clay content from the NIR spectral measurements in accordance with a pre-determined chemometric model correlating NIR spectral measurements and actual clay content of MFT samples.

5. The process of any one of claims 1 to 4, wherein diluting of the in-line MFT flow based on the NIR derived clay content is controlled according to feedforward control.

6. The process of any one of claims 1 to 5, wherein the CWR of the diluted MFT flow is a pre-determined CWR value.

7. The process of any one of claims 1 to 6, wherein diluting of the in-line MFT flow comprises injecting an aqueous stream co-directionally into the MFT flow.

8. The process of any one of claim 7, wherein diluting of the in-line MFT flow comprises injecting the aqueous stream within a central region of the MFT flow.

9. The process of claim 7 or 8, wherein diluting of the in-line MFT flow is controlled by adjusting of a flowrate of the aqueous stream.

10. The process of any one of claims 1 to 9, wherein diluting of the in-line MFT flow is performed via multiple dilution inlets provided along a flowpath of the MFT flow, wherein the dilution inlets are controlled for injection via only one of the dilution inlets at a time.

1 1. A dilution unit for injecting a dilution fluid into thick fine tailings (TFT), the dilution unit comprising: a main pipe for transporting an in-line TFT flow; and at least one injector quill comprising: a feed pipe section extending into the main pipe and receiving a flow of the dilution fluid; and an outlet at a distal end of the feed pipe section, the outlet being configured and positioned within the main pipe to expel the dilution fluid co-directionally and within a central region of the TFT flow to produce a diluted TFT flow.

12. The dilution unit of claim 11 , wherein the outlet is positioned at a cross-sectional center-point of the main pipe.

13. The dilution unit of claim 1 1 or 12, wherein the at least one injector quill comprises a first injector quill and a second injector quill.

14. The dilution unit of claim 13, wherein the first and second injector quills are located in spaced-apart relation to each other along a length of the main pipe.

15. The dilution unit of claim 13 or 14, wherein the first injector quill is sized and configured to provide lower flowrate of the dilution fluid compared to the second injector quill.

16. The dilution unit of claim 15, wherein the feed pipe section of the first injector quill has a smaller diameter than that of the feed pipe section of the second injector quill.

17. The dilution unit of claim 15 or 16, wherein the first injector quill is located upstream from the second injector quill.

18. The dilution unit of any one of claims 13 to 17, wherein the first and second injector quills are configured for injection of the dilution fluid via only one of the injector quills at a time.

19. The dilution unit of any one of claims 13 to 18, wherein the first and second injector quills further comprise a control assembly configured to control the flowrate of the dilution fluid injected into the TFT.

20. The dilution unit of claim 19, wherein the control assembly comprises valves and a controller configured to adjust the valves.

21. The dilution unit of any one of claims 13 to 20, further comprising a common dilution fluid header in fluid communication with the first and second injector quills for supplying dilution fluid thereto.

22. The dilution unit of any one of claims 11 to 21 , wherein the feed pipe section is oriented at an oblique angle relative to the main pipe.

23. The dilution unit of claim 22, wherein the oblique angle is between about 60° and about 30° facing upstream of a flow direction.

24. The dilution unit of claim 23, wherein the oblique angle is about 45°.

25. The dilution unit of any one of claims 22 to 24, wherein the outlet is formed by an oblique cut through an end of the feed pipe section.

26. The dilution unit of claim 25, wherein the oblique cut is provided to form an annular surface of the outlet that is substantially normal to a length of the main pipe.

27. The dilution unit of any one of claims 11 to 24, wherein the outlet comprises a nozzle.

28. The dilution unit of claim 27, wherein the nozzle comprises an elbow-type nozzle that is oriented and positioned to point along a central longitudinal axis of the main pipe.

29. The dilution unit of any one of claims 1 1 to 28, further comprising: a bypass line configured to bypass at least a portion of the TFT past the at least one injector quill.

30. The dilution unit of claim 29, wherein the bypass line comprises: an inlet portion in fluid communication with the main pipe upstream of the at least one injector quill; an outlet portion in fluid communication with the main pipe downstream of the at least one injector quill; and a flow control assembly comprising valves or gates in order to provide or cease fluid communication with the main pipe.

31. The dilution unit of any one of claims 11 to 30, wherein the at least one injector quill is configured to provide sufficient dilution fluid to produce the diluted TFT flow having a clay-to-water ratio (CWR) within a CWR range between about 0.25 and about 0.33.

32. The dilution unit of claim 31 , wherein the at least one injector quill is configured to produce the diluted TFT flow having a target CWR value within the CWR range.

33. The dilution unit of any one of claims 1 1 to 32, wherein the TFT is derived from an oil sands extraction operation.

34. The dilution unit of any one of claims 11 to 33, wherein the at least one injector quill is configured for injection of a liquid dilution stream comprising fresh water, process water, and/or recycle water streams from an extraction operation.

35. A pre-treatment system for pre-treating thick fine tailings (TFT) prior to flocculation and dewatering, the pre-treatment system comprising: a dilution unit for injecting a dilution fluid into a TFT flow to produce a diluted TFT flow; and a homogenization unit comprising: an upstream pipe section receiving the diluted TFT flow; a plurality of in-line mixers for subjecting the diluted TFT flow to mixing to produce a homogenized diluted TFT flow; and a downstream pipe section for supplying the homogenized diluted TFT flow to a flocculation unit.

36. The pre-treatment system of claim 35, wherein the dilution unit is as defined in any one of claims 1 1 to 34.

37. The pre-treatment system of claim 35, wherein the dilution unit comprises one or more branch lines in fluid communication with the TFT flow to form one or more corresponding Tee junctions.

38. The pre-treatment system of claim 37, wherein the branch line is configured and operated such that a dilution fluid jet entering the TFT flow generally aligns with a central region of the TFT flow.

39. The pre-treatment system of claim 37, wherein the dilution unit comprises multiple sequential branch lines having different pipe diameters for providing different flowrates of the dilution fluid into the TFT flow.

40. The pre-treatment system of claim 37, wherein the dilution unit comprises multiple sequential side streams entering the TFT flow, and each side stream comprises multiple branch lines provided around the TFT flow for injection therein at different injection angles.

41. The pre-treatment system of any one of claims 35 to 40, wherein the in-line mixers are arranged in series.

42. The pre-treatment system of any one of claims 35 to 41 , wherein the in-line mixers comprise static mixers.

43. The pre-treatment system of any one of claims 42, wherein at least eight of the static mixers are provided in series.

44. The pre-treatment system of any one of claims 35 to 41 , wherein the upstream pipe section has a smaller diameter than a supply line supplying the diluted TFT thereto.

45. The pre-treatment system of any one of claims 35 to 41 , wherein the dilution unit, the homogenization unit, and a connection conduit therebetween are configured such that the dilution fluid within the TFT remains generally spaced away from side walls of the connection conduit until the diluted TFT arrives at the homogenization unit.

46. A process for dewatering thick fine tailings (TFT), comprising: supplying a TFT flow to the dilution unit as defined in any one of claims 11 to 34; supplying the diluted TFT flow to an in-line homogenization unit to produce a pre- treated TFT flow; subjecting the pre-treated TFT flow to flocculation to produce a flocculation material; and dewatering the flocculation material to produce an aqueous stream and a dewatered solids-enriched material.

47. A process for dewatering thick fine tailings (TFT), comprising: supplying a TFT flow to a dilution unit to produce a diluted TFT having a target clay content within a pre-determined clay-to-water (CWR) range; supplying the diluted TFT flow to an in-line homogenization unit to produce a pre- treated TFT flow; subjecting the pre-treated TFT flow to flocculation with a flocculant dosage based on the target clay content, to produce a flocculation material; dewatering the flocculation material to produce an aqueous stream and a dewatered solids-enriched material.

48. The process of claim 47, wherein the dilution unit is as defined in any one of claims 1 1 to 34.

49. The process of any one of claims 47 or 48, further comprising: retrieving the TFT from a tailings source to produce the TFT flow which has variable clay content; monitoring clay content of the TFT flow on-line or at-line; and controlling the dilution unit in response to the variable clay content of the TFT flow via feedforward control, in order to maintain the target clay content.

50. The process of any one of claims 47 to 49, further comprising: monitoring clay content of the diluted TFT and/or the pre-treated TFT; controlling the dilution unit in response to the clay content of the diluted TFT via feedback control, in order to maintain the target clay content.

51. A process for treating thick fine tailings (TFT), comprising: determining clay content of an in-line flow of the TFT using near infrared (NIR) spectrometry; injecting a flocculant into the TFT at a flocculant dosage based on the clay content of the TFT to produce a flocculation material; and dewatering the flocculation material to produce an aqueous stream and a dewatered flocculated material.

52. The process of claim 51 , further comprising: diluting the TFT prior to injecting the flocculant.

53. The process of claim 52, wherein the diluting is performed upstream of the NIR spectrometry.

54. The process of claim 52, wherein the diluting is performed downstream of the NIR spectrometry.

55. The process of claim 54, wherein the diluting is controlled based on the clay content using NIR spectrometry, in order to obtain a diluted TFT flow having a target clay-to- water ratio (CWR) which is subjected to flocculation.

56. The process of claim 55, wherein the target CWR is within a CWR range between about 0.25 and about 0.33.

57. The process of any one of claims 54 to 56, further comprising: controlling dilution in response to the clay content via feedforward control, in order to maintain the target CWR.

58. The process of claim 53, further comprising: controlling dilution in response to the clay content via feedback control, in order to maintain a target clay content.

59. A process for treating thick fine tailings (TFT), comprising: determining clay content of an in-line flow of the TFT using near infrared (NIR) spectrometry; diluting the TFT based on the clay content determined by the NIR spectrometry to obtain a diluted TFT having a target clay content; injecting a flocculant into the TFT based on the target clay content of the diluted TFT, to produce a flocculation material; and dewatering the flocculation material to produce an aqueous stream and a dewatered solids-enriched material.

60. A process for treating thick fine tailings (TFT), comprising: diluting a TFT flow to obtain a diluted TFT; determining clay content of the diluted TFT using near infrared (NIR) spectrometry; controlling the diluting of the TFT flow based on the clay content determined by the NIR spectrometry, to maintain a target clay content of the diluted TFT; injecting a flocculant into the diluted TFT, to produce a flocculation material; and dewatering the flocculation material to produce an aqueous stream and a dewatered solids-enriched material.

61. A process for treating thick fine tailings (TFT), comprising: determining flocculant concentration of an in-line flow of a flocculant solution using near infrared (NIR) spectrometry; determining clay content of an in-line flow of the TFT; injecting the flocculant solution into the TFT at a flocculant dosage based on the clay content of the TFT and the flocculant concentration, to produce a flocculation material; dewatering the flocculation material to produce an aqueous stream and a solids- enriched material.

62. The process of claim 61 , further comprising: controlling the flocculant concentration in the flocculant solution using feedback control.

63. The process of claim 61 or 62, further comprising: controlling the flocculant dosage in response to a change in the clay content, comprising: in response to an increase in the clay content: increasing the flocculant concentration in the flocculant solution, increasing a flowrate of the flocculant solution injected into the TFT, increasing a relative flowrate of the flocculant solution with respect to the TFT, and/or performing or increasing dilution of the TFT with an aqueous stream to reduce the clay content thereof; and in response to a decrease in the clay content: decreasing the flocculant concentration in the flocculant solution, decreasing a flowrate of the flocculant solution injected into the TFT, decreasing a relative flowrate of the flocculant solution with respect to the TFT, and/or decreasing or ceasing dilution of the TFT with an aqueous stream to reduce the clay content thereof.

64. The process of any one of claims 61 to 63, wherein determining the clay content of the in-line flow of the TFT is performed using NIR spectrometry.

65. The process of any one of claims 61 to 64, wherein the NIR spectrometry comprises obtaining NIR spectral measurements on-line or at-line.

66. The process of claim 65, wherein the NIR spectral measurements are obtained using reflectance-type NIR spectroscopy.

67. The process of claim 65 or 66, further comprising: determining an NIR derived flocculant concentration from the NIR spectral measurements in accordance with a pre-determined chemometric model correlating NIR spectral measurements and actual flocculant concentration in flocculant solution samples; and controlling injection of the flocculant solution based on the NIR derived flocculant concentration.

68. The process of any one of claims 61 to 67, wherein the flocculant concentration and the clay content of the TFT flow are continuously determined; and the flocculant dosage is continuously adjusted based on the flocculant concentration and the clay content.

69. A process for treating thick fine tailings (TFT), comprising: injecting a flocculant into a TFT flow to produce a flocculation material; obtaining near infrared (NIR) spectral measurements of the flocculation material using NIR spectroscopy, to provide an NIR derived dewatering parameter; dewatering the flocculation material to produce an aqueous stream and a dewatered solids-enriched material; and controlling a process operating condition based on the NIR derived dewatering parameter using feedback control.

70. The process of claim 69, wherein the controlling comprises: adjusting injection of the flocculant into the TFT flow as the process operating condition, in response to a change in the dewatering parameter.

71. The process of claim 69 or 70, wherein the controlling comprises: adjusting dilution of the TFT flow prior to injection of the flocculant as the process operating condition, in response to a change in the dewatering parameter.

72. The process of any one of claims 69 to 71 , wherein the controlling comprises: adjusting clay content of the TFT flow prior to injection of the flocculant as the process operating condition, in response to a change in the dewatering parameter.

73. The process of any one of claims 69 to 72, wherein the dewatering parameter comprises Net Water Release (NWR) determined after a NWR drainage time, wherein:

74. The process of claim 73, wherein the NWR drainage time is between 20 minutes and 48 hours, between one hour and 36 hours or between 12 hours and 24 hours.

75. The process of claim 73 or 74, wherein the controlling comprises adjusting the process operating condition when the NWR falls below an NWR threshold.

76. The process of claim 75, wherein the NWR threshold is between 0.4 to 0.6 when the NWR drainage time is between 12 hours and 36 hours.

77. The process of any one of claims 69 to 76, wherein the TFT is derived from an oil sands extraction operation.

78. The process of any one of claims 69 to 77, wherein the dewatering comprises subjecting the flocculation material to thickening in a thickener vessel and/or filtering by a filter device.

79. The process of any one of claims 69 to 77, wherein the dewatering comprises sub- aerial deposition.

80. The process of claim 79, wherein the sub-aerial deposition is performed onto a sloped deposition surface.

81. A method for controlling polymer flocculant dosing into thick fine tailings (TFT), comprising: continuously obtaining near infrared (NIR) spectral measurements of the TFT using NIR spectroscopy, to provide an NIR derived clay content of the TFT; continuously obtaining NIR spectral measurements of a flocculant solution comprising the polymer flocculation using NIR spectroscopy, to provide an NIR derived flocculation concentration in the flocculant solution; and injecting the flocculant solution into the TFT to produce a flocculation material; and dosing the flocculant on a clay basis in accordance with the NIR derived flocculation concentration and the NIR derived clay content of the TFT.

82. The method of claim 81 , further comprising: diluting the TFT prior to injecting the flocculant solution to produce a diluted TFT.

83. The method of claim 82, wherein the NIR derived clay content in the TFT is obtained upstream of the diluting.

84. The method of claim 82, wherein the NIR derived clay content in the TFT is obtained for the diluted TFT downstream of the diluting.

85. The method of any one of claims 82 to 84, wherein the diluting is controlled so that the diluted TFT has a clay-to-water ratio (CWR) between about 0.25 and about 0.33.

86. The method of any one of claims 81 to 85, wherein the TFT is derived from an oil sands extraction operation.

87. The method of any one of claims 81 to 86, further comprising dewatering the flocculation material.

88. The method of claim 87, wherein the dewatering comprises subjecting the flocculation material to thickening in a thickener vessel and/or filtering by a filter device.

89. The method of claim 87, wherein the dewatering comprises sub-aerial deposition onto a sloped deposition surface.

90. The method of any one of claims 81 to 89, wherein each of the NIR spectral measurements is obtained using a reflectance-type NIR probe.