Pre-treatment of oil sands fine tailings by debris removal

Abstract

The present disclosure provides systems, processes, devices and techniques for pre- treating oil sands fine tailings in order to remove coarse debris from oil sands fine tailings and produce screened oil sands fine tailings, the screened oil sands fine tailings having improved reactivity and / or mixability with chemicals in a subsequent chemical tailings treatment operation that can include dewatering. The pre-treatment screening techniques can further produce screened oil sands fine tailings thereby enabling a reduction in terms of damage, clogging and / or plugging of downstream equipment used in the downstream tailings treatment operation, which can include flocculation and dewatering.

Description

PRE-TREATMENT OF OIL SANDS FINE TAILINGS BY DEBRIS REMOVAL TECHNICAL FIELD

[0001] The technical field generally relates to the treatment of mine tailings derived from mining operations, and more particularly to techniques that can involve screening for removing coarse debris from oil sands fine tailings for example prior to flocculation and dewatering operations. BACKGROUND

[0002] Oil sands tailings are generated from hydrocarbon extraction process operations that separate the valuable hydrocarbons from oil sand ore. There are various types of oil sands tailings, such as mature fine tailings (MFT) formed in a tailings pond. Tailings materials that have a high fines content can be subjected to dewatering operations, which can involve adding chemical additives such as coagulants and / or flocculants and then separating solid minerals from the water in the tailings by supplying the treated tailings to a sub-aerial deposition area for deposition in thin lifts for drying, to a dewatering device, or to a pit for settling of the mineral solids.

[0003] Prior to addition of a flocculant or other chemical agents to the tailings material, the fine tailings can be screened to remove coarse debris that can cause issues in downstream operations. For example, there exist methods and apparatuses for removing coarse debris from fine tailings prior to a flocculation and dewatering operation. However, there is still a need for enhancements in terms of methods and screening apparatuses for coarse debris removal from tailings streams. SUMMARY

[0004] The present disclosure provides processes, systems, devices and techniques for pre-treating an aqueous suspension including fine solid particles and coarse debris, in order to remove coarse debris prior to further treatments. The present techniques are particularly claimed and described with respect to an aqueous suspension derived from mining operations and referred to as mining tailings, including oil sands fine tailings, such as mature fine tailings (MFT).

[0005] In one aspect, there is provided pre-treatment screening assembly comprising a spillbox feed tank comprising a bottom wall and side walls extending upwardly from the bottom wall, thereby defining a tank cavity, a tailings inlet provided in the bottom wall for receiving a tailings fluid flow into the tank cavity, and a screening device having a screening surface receiving the tailings fluid flow from the spillbox feed tank, the screening surface being configured to allow material with a predetermined size that is included in the tailings fluid flow to flow through the screening surface and separate coarse debris from the tailings fluid flow, thereby separating the tailings fluid into a coarse debris fraction and a screened tailings fluid; and a collector body arranged below the screening surface of the screening device to receive the screened tailings fluid, the collector body comprising side walls and a bottom wall defining together a collecting cavity.

[0006] In another aspect, there is provided pre-treatment screening assembly comprising a spillbox feed tank comprising a bottom wall and side walls extending upwardly from the bottom wall, thereby defining a tank cavity, and a tailings inlet provided above a portion of the tank cavity for discharging downwardly a tailings fluid flow into the tank cavity; a screening device having a screening surface receiving the tailings fluid flow from the spillbox feed tank, the screening surface being configured to allow material with a predetermined size that is included in the tailings fluid flow to flow through the screening surface and separate coarse debris from the tailings fluid flow, thereby separating the tailings fluid into a coarse debris fraction and a screened tailings fluid; and a collector body arranged below the screening surface of the screening device to receive the screened tailings fluid, the collector body comprising side walls and a bottom wall defining together a collecting cavity.

[0007] In another aspect, there is provided pre-treatment screening assembly comprising a spillbox feed tank comprising a bottom wall and side walls extending upwardly from the bottom wall, thereby defining a tank cavity, and a tailings inlet provided substantially centrally in the bottom wall for receiving a tailings fluid flow into the tank cavity; a screening device having a screening surface receiving the tailings fluid flow spilling from the spillbox feed tank, the screening surface being configured to allow material with a predetermined size that is included in the tailings fluid flow to flow through the screening surface and separate coarse debris from the tailings fluid flow, thereby separating the tailings fluid into a coarse debris fraction and a screened tailings fluid; and a collector body arranged below the screening surface of the screening device to receive the screened tailings fluid.

[0008] In another aspect, there is provided a pre-treatment screening assembly comprising a spillbox feed tank comprising a bottom wall and side walls extending upwardly from the bottom wall, thereby defining a tank cavity, and a tailings inlet comprising a distribution pipe extending substantially horizontally above a portion of the tank cavity for discharging downwardly a tailings fluid flow into the tank cavity; a screening device having a screening surface receiving the tailings fluid flow from the spillbox feed tank, the screening surface being configured to allow material with a predetermined size that is included in the tailings fluid flow to flow through the screening surface and separate coarse debris from the tailings fluid flow, thereby separating the tailings fluid into a coarse debris fraction and a screened tailings fluid; and a collector body arranged below the screening surface of the screening device to receive the screened tailings fluid.

[0009] In another aspect, there is provided a pre-treatment screening assembly comprising a spillbox feed tank comprising a bottom wall and side walls extending upwardly from the bottom wall, thereby defining a tank cavity, a tailings inlet for receiving a tailings fluid flow into the tank cavity, and an overflow weir extending outwardly from an upper portion of the tank cavity; a screening device having a screening surface receiving the tailings fluid flow spilling over the overflow weir of the spillbox feed tank, the screening surface being configured to allow material with a predetermined size that is included in the tailings fluid flow to flow through the screening surface and separate coarse debris from the tailings fluid flow, thereby separating the tailings fluid into a coarse debris fraction and a screened tailings fluid; and a collector body arranged below the screening surface of the screening device to receive the screened tailings fluid; wherein a width of the overflow weir is smaller than a width of the screening surface.

[0010] In another aspect, there is provided a pre-treatment screening assembly comprising a spillbox feed tank comprising a bottom wall and side walls extending upwardly from the bottom wall, thereby defining a tank cavity, a tailings inlet for receiving a tailings fluid flow into the tank cavity, and an adjustable valve configured to cooperate with the tailings inlet in response to the level measured by the level sensor; a screening device having a screening surface receiving the tailings fluid flow from the spillbox feed tank, the screening surface being configured to allow material with a predetermined size that is included in the tailings fluid flow to flow through the screening surface and separate coarse debris from the tailings fluid flow, thereby separating the tailings fluid into a coarse debris fraction and a screened tailings fluid; a collector body arranged below the screening surface of the screening device to receive the screened tailings fluid, the collector body comprising side walls and a bottom wall defining together a collecting cavity; and a level sensor for measuring a tailings fluid level in one of the tank cavity and the collecting cavity.

[0011] In another aspect, there is provided a pre-treatment screening assembly comprising a spillbox feed tank comprising a bottom wall and side walls extending upwardly from the bottom wall, thereby defining a tank cavity, a tailings inlet for receiving a tailings fluid flow into the tank cavity, and an overflow weir extending outwardly from an upper portion of the tank cavity; a screening device comprising a screening surface receiving the tailings fluid flow spilling over the overflow weir of the spillbox feed tank, the screening surface being configured to allow material with a predetermined size that is included in the tailings fluid flow to flow through the screening surface and separate coarse debris from the tailings fluid flow, thereby separating the tailings fluid into a coarse debris fraction and a screened tailings fluid, and a cleaning device to remove the coarse debris from the screening surface; and a collector body arranged below the screening surface of the screening surface to receive the screened tailings fluid.

[0012] In another aspect, there is provided a pre-treatment screening assembly comprising a screening device comprising a screening surface receiving a tailings fluid flow, the screening surface being configured to allow material with a predetermined size that is included in the tailings fluid flow to flow through the screening surface and separate coarse debris from the tailings fluid flow, thereby separating the tailings fluid into a coarse debris fraction and a screened tailings fluid, the screening surface defining a first adjustable inclination angle with a horizontal direction; and a collector body arranged below the screening surface of the screening surface to receive the screened tailings fluid.

[0013] In another aspect, there is provided a pre-treatment screening assembly comprising a screening device comprising a screening surface receiving a tailings fluid flow, the screening surface being configured to allow material with a predetermined size that is included in the tailings fluid flow to flow through the screening surface and separate coarse debris from the tailings fluid flow, thereby separating the tailings fluid into a coarse debris fraction and a screened tailings fluid, and a mechanical cleaning device configured to mechanically remove the coarse debris from the screening surface; and a collector body arranged below the screening surface of the screening surface to receive the screened tailings fluid.

[0014] In another aspect, there is provided a pre-treatment screening assembly comprising a screening device comprising a screening surface receiving a tailings fluid flow, the screening surface being configured to allow material with a predetermined size that is included in the tailings fluid flow to flow through the screening surface and separate coarse debris from the tailings fluid flow, thereby separating the tailings fluid into a coarse debris fraction and a screened tailings fluid, and a cleaning device configured to remove the coarse debris from the screening surface; a collector body arranged below the screening surface of the screening surface to receive the screened tailings fluid; and a debris collection bin arranged under or close to the screening device to collect the coarse debris removed from the screening surface.

[0015] In another aspect, there is provided a pre-treatment screening assembly comprising a spillbox feed tank comprising a bottom wall and side walls extending upwardly from the bottom wall, thereby defining a tank cavity, a tailings inlet for receiving a tailings fluid flow into the tank cavity, and an overflow weir extending outwardly from an upper portion of the tank cavity; a screening device comprising a screening surface receiving the tailings fluid flow spilling over the overflow weir of the spillbox feed tank, the screening surface being configured to allow material with a predetermined size that is included in the tailings fluid flow to flow through the screening surface and separate coarse debris from the tailings fluid flow, thereby separating the tailings fluid into a coarse debris fraction and a screened tailings fluid; and a collector body arranged below the screening surface of the screening device and having a collecting cavity to receive the screened fluid, the collector body comprising a discharge opening formed in a bottom portion of the collector body for collecting and easily removing debris that build up in the collector body.

[0016] In another aspect, there is provided a pre-treatment screening assembly comprising a screening device comprising a screening surface receiving a tailings fluid flow, the screening surface being configured to allow material with a predetermined size that is included in the tailings fluid flow to flow through the screening surface and separate coarse debris from the tailings fluid flow, thereby separating the tailings fluid into a coarse debris fraction and a screened tailings fluid; and a collector body arranged below the screening surface of the screening device and comprising a bottom wall and side walls extending from the bottom wall, thereby defining a collecting cavity to receive the screened fluid, a discharge opening formed in a bottom portion of the collector body for collecting and easily removing debris that build up in the collector body, the side walls converging toward the discharge opening.

[0017] In another aspect, there is provided a pre-treatment screening assembly comprising a screening device comprising a screening surface receiving a tailings fluid flow, the screening surface being configured to allow material with a predetermined size that is included in the tailings fluid flow to flow through the screening surface and separate coarse debris from the tailings fluid flow, thereby separating the tailings fluid into a coarse debris fraction and a screened tailings fluid; and a collector body arranged below the screening surface of the screening device and having a collecting cavity to receive the screened fluid, the collector body comprising a deflector plate arranged in the collecting cavity.

[0018] In another aspect, there is provided a pre-treatment screening assembly comprising a plurality of spillbox feed tanks, each spillbox feed tank comprising a bottom wall and side walls extending upwardly from the bottom wall, thereby defining a tank cavity, a tailings inlet for receiving a tailings fluid flow into the tank cavity, an overflow weir extending outwardly from an upper portion of the tank cavity, and an adjustable valve configured to cooperate with the tailings inlet; a plurality of screening devices, each screening device having a screening surface receiving the tailings fluid flow spilling over the overflow weir of one of the spillbox feed tanks, the screening surface being configured to allow material with a predetermined size that is included in the tailings fluid flow to flow through the screening surface and separate coarse debris from the tailings fluid flow, thereby separating the tailings fluid into a coarse debris fraction and a screened tailings fluid; and a collector body arranged below the screening surface of the screening devices having a collecting cavity to receive the screened tailings fluids of the plurality of screening devices; the adjustable valves of the spillbox feed tanks being adjusted for the different spillbox feed tanks to have a substantially similar outlet flow.

[0019] In another aspect, there is provided a pre-treatment screening assembly comprising a spillbox feed tank comprising a bottom wall and side walls extending upwardly from the bottom wall, thereby defining a tank cavity, a tailings inlet for receiving a tailings fluid flow into the tank cavity, and a screening device having a screening surface receiving the tailings fluid flow from the spillbox feed tank, the screening surface being configured to allow material with a predetermined size that is included in the tailings fluid flow to flow through the screening surface and separate coarse debris from the tailings fluid flow, thereby separating the tailings fluid into a coarse debris fraction and a screened tailings fluid; a collector body arranged below the screening surface of the screening device to receive the screened tailings fluid; and a frame to which the spillbox feed tank, the screening device and the collector body are mounted, for the spillbox feed tank, the screening device and the collector body to be spaced apart from a ground surface supporting the frame.

[0020] In another aspect, there is provided a pre-treatment screening assembly comprising a plurality of spillbox feed tanks, each spillbox feed tank comprising a bottom wall and side walls extending upwardly from the bottom wall, thereby defining a tank cavity, a tailings inlet for receiving a tailings fluid flow into the tank cavity, and an overflow weir extending outwardly from an upper portion of the tank cavity; at least two screening devices, each screening device defining a longitudinal direction and having two opposed longitudinal ends, said at least two screening devices extending side to side substantially parallel, and each screening device having a screening surface receiving the tailings fluid flow spilling over the overflow weir of one of the spillbox feed tanks, the screening surface being configured to allow material with a predetermined size that is included in the tailings fluid flow to flow through the screening surface and separate coarse debris from the tailings fluid flow, thereby separating the tailings fluid into a coarse debris fraction and a screened tailings fluid; an access platform extending along the screening devices at one of their longitudinal ends; and a collector body arranged below the screening surface of the screening devices having a collecting cavity to receive the screened tailings fluids.

[0021] In another aspect, there is provided a pre-treatment site comprising a pre- treatment screening assembly according to the present disclosure; an inlet line fluidly connected to the pre-treatment screening assembly to discharge a tailings fluid flow onto the screening surface of the screening device; and a discharge line fluidly connected to the collector body for downstream treatment operations of the screened tailings fluid.

[0022] In another aspect, there is provided a process for screening coarse debris from a tailings fluid flow coming from an inlet line, the process comprising providing the tailings fluid flow to a pre-treatment screening assembly comprising a spillbox feed tank having a bottom wall and side walls extending upwardly from the bottom wall, thereby defining a tank cavity, a screening device and a collector body; connecting the inlet line to a tailings inlet formed in the bottom wall of the spillbox feed tank so as to form in the tank cavity a substantially vertical tailings fluid inlet flow; filling the tank cavity of the spillbox feed tank with the tailings fluid flow; discharging a tailings fluid outlet flow from the tank cavity onto the screening device, the screening device having a screening surface configured to allow material with a predetermined size that is included in the tailings fluid flow to flow through the screening surface and separate coarse debris from the tailings fluid flow, thereby separating the tailings fluid into a coarse debris fraction and a screened tailings fluid; and collecting the screened tailings fluid into the collector body

[0023] In another aspect, there is provided a process for screening coarse debris from a tailings fluid flow coming from an inlet line, the process comprising providing the tailings fluid flow to a pre-treatment screening assembly comprising a spillbox feed tank having a bottom wall and side walls extending upwardly from the bottom wall, thereby defining a tank cavity, a screening device and a collector body; connecting the inlet line to a tailings inlet provided above a portion of the tank cavity for discharging downwardly the tailings fluid flow into the tank cavity; filling the tank cavity of the spillbox feed tank with the tailings fluid flow; discharging a tailings fluid outlet flow from the tank cavity onto the screening device, the screening device having a screening surface configured to allow material with a predetermined size that is included in the tailings fluid flow to flow through the screening surface and separate coarse debris from the tailings fluid flow, thereby separating the tailings fluid into a coarse debris fraction and a screened tailings fluid; and collecting the screened tailings fluid into the collector body.

[0024] In another aspect, there is provided a process for screening coarse debris from a tailings fluid flow coming from an inlet line, the process comprising providing the tailings fluid flow to a pre-treatment screening assembly comprising a spillbox feed tank with a tank cavity, a screening device and a collector body; connecting the inlet line to a tailings inlet formed in the spillbox feed tank; filling the tank cavity of the spillbox feed tank with the tailings fluid flow; discharging a tailings fluid outlet flow from the tank cavity onto the screening device, the screening device having a screening surface configured to allow material with a predetermined size that is included in the tailings fluid flow to flow through the screening surface and separate coarse debris from the tailings fluid flow, thereby separating the tailings fluid into a coarse debris fraction and a screened tailings fluid; collecting the screened tailings fluid into the collector body; and removing the coarse debris from the screening surface.

[0025] In another aspect, there is provided a process for screening coarse debris from a tailings fluid flow coming from an inlet line and going into a discharge line, the process comprising providing the tailings fluid flow to a pre-treatment screening assembly comprising a spillbox feed tank with a tank cavity, a screening device and a collector body having a discharge outlet connected to the discharge line; connecting the inlet line to a tailings inlet formed in the spillbox feed tank; filling the tank cavity of the spillbox feed tank with the tailings fluid flow; discharging a tailings fluid outlet flow from the tank cavity onto the screening device, the screening device having a screening surface configured to allow material with a predetermined size that is included in the tailings fluid flow to flow through the screening surface and separate coarse debris from the tailings fluid flow, thereby separating the tailings fluid into a coarse debris fraction and a screened tailings fluid; collecting the screened tailings fluid into the collector body; and deflecting the screened tailings fluid inlet flow filling the collector body from the discharge outlet.

[0026] In another aspect, there is provided a process for screening coarse debris from a tailings fluid flow coming from an inlet line and going into a discharge line, the process comprising providing the tailings fluid flow to a pre-treatment screening assembly comprising a spillbox feed tank with a tank cavity, a screening device and a collector body having a discharge outlet connected to the discharge line; connecting the inlet line to a tailings inlet formed in the spillbox feed tank; filling the tank cavity of the spillbox feed tank with the tailings fluid flow; discharging a tailings fluid outlet flow from the tank cavity onto the screening device, the screening device having a screening surface configured to allow material with a predetermined size that is included in the tailings fluid flow to flow through the screening surface and separate coarse debris from the tailings fluid flow, thereby separating the tailings fluid into a coarse debris fraction and a screened tailings fluid; collecting the screened tailings fluid into the collector body; and removing debris building up in the collector body.

[0027] In another aspect, there is provided a process for screening coarse debris from a tailings fluid flow coming from an inlet line, the process comprising providing the tailings fluid flow to a pre-treatment screening assembly comprising at least two spillbox feed tanks having each a tank cavity with an upper portion and an overflow weir extending outwardly from the upper portion of the tank cavity, the pre-treatment screening assembly further comprising a screening device and a collector body; connecting the inlet line to a tailings inlet formed in each of the spillbox feed tanks; filling each tank cavity of the spillbox feed tanks with the tailings fluid flow for the tailings fluid flow to reach an overflow weir of each of the spillbox feed tanks; discharging a tailings fluid outlet flow over the overflow weir of the tank cavity onto the screening device, the screening device having a screening surface configured to allow material with a predetermined size that is included in the tailings fluid flow to flow through the screening surface and separate coarse debris from the tailings fluid flow, thereby separating the tailings fluid into a coarse debris fraction and a screened tailings fluid; collecting the screened tailings fluid into the collector body; and adjusting the outflow rate of at least one of the tailings fluid outlet flow for the different spillbox feed tanks to have a substantially similar outlet flow rate.

[0028] In another aspect, there is provided a pre-treatment screening assembly comprising a spillbox feed tank defining a tank cavity and comprising a bottom wall, and a tailings inlet provided in the bottom wall for receiving a tailings fluid flow into the tank cavity; a screening device having a screening surface receiving the tailings fluid flow from the spillbox feed tank, the screening surface being configured to allow material smaller than a predetermined size that is included in the tailings fluid flow to flow through the screening surface and separate coarse debris larger than or equal to the predetermined size from the tailings fluid flow, thereby separating the tailings fluid into a coarse debris fraction and a screened tailings fluid; and a collector body arranged below the screening surface of the screening device to receive the screened tailings fluid.

[0029] In another aspect, there is provided pre-treatment screening assembly comprising a spillbox feed tank defining a tank cavity and comprising a tailings inlet provided above an upper portion of the tank cavity for discharging downwardly a tailings fluid flow into the tank cavity; a screening device having a screening surface receiving the tailings fluid flow from the spillbox feed tank, the screening surface being configured to allow material smaller than a predetermined size that is included in the tailings fluid flow to flow through the screening surface and separate coarse debris larger than or equal to the predetermined size from the tailings fluid flow, thereby separating the tailings fluid into a coarse debris fraction and a screened tailings fluid; and a collector body arranged below the screening surface of the screening device to receive the screened tailings fluid.

[0030] In another aspect, there is provided pre-treatment screening assembly comprising a spillbox feed tank defining a tank cavity and comprising a tailings inlet for receiving a tailings fluid flow into the tank cavity; an adjustable inlet valve configured to adjust the tailings fluid inlet flow in the spillbox feed tank; a screening device having a screening surface receiving the tailings fluid flow from the spillbox feed tank, the screening surface being configured to allow material smaller than a predetermined size that is included in the tailings fluid flow to flow through the screening surface and separate coarse debris larger than or equal to the predetermined size from the tailings fluid flow, thereby separating the tailings fluid into a coarse debris fraction and a screened tailings fluid; a collector body arranged below the screening surface of the screening device to receive the screened tailings fluid and defining a collecting cavity; and one or more level sensors for measuring a tailings fluid level in the tank cavity and / or the collecting cavity. The adjustable inlet valve is configured to adjust the tailings fluid inlet flow in the spillbox feed tank in response to the tailings fluid level measured by the one or more level sensors.

[0031] In another aspect, there is provided a pre-treatment screening assembly comprising a spillbox feed tank defining a tank cavity and comprising a tailings inlet for receiving a tailings fluid flow into the tank cavity; a screening device comprising a screening surface receiving the tailings fluid flow from the spillbox feed tank, the screening surface being configured to allow material smaller than a predetermined size that is included in the tailings fluid flow to flow through the screening surface and separate coarse debris larger than or equal to the predetermined size from the tailings fluid flow, thereby separating the tailings fluid into a coarse debris fraction and a screened tailings fluid, and a cleaning device to remove the coarse debris from the screening surface; and a collector body arranged below the screening surface of the screening device to receive the screened tailings fluid.

[0032] In another aspect, there is provided pre-treatment screening assembly comprising a screening device comprising a screening surface receiving a tailings fluid flow, the screening surface being configured to allow material smaller than a predetermined size that is included in the tailings fluid flow to flow through the screening surface and separate coarse debris larger than or equal to the predetermined size from the tailings fluid flow, thereby separating the tailings fluid into a coarse debris fraction and a screened tailings fluid, the screening surface defining an inclination angle with respect to horizontal; a cleaning device configured to cooperate with the screening device to adjust the inclination angle when the screening device is configured into a cleaning mode; and a collector body arranged below the screening surface of the screening device to receive the screened tailings fluid.

[0033] In another aspect, there is provided pre-treatment screening assembly comprising a screening device comprising a screening surface receiving a tailings fluid flow, the screening surface being configured to allow material smaller than a predetermined size that is included in the tailings fluid flow to flow through the screening surface and separate coarse debris larger than or equal to the predetermined size from the tailings fluid flow, thereby separating the tailings fluid into a coarse debris fraction and a screened tailings fluid, a collector body arranged below the screening surface of the screening device to receive the screened tailings fluid; and a collection bin arranged under or close to the screening device to collect the coarse debris removed from the screening surface and / or a tailings fluid loss resulting from a tailings running off of the screening surface.

[0034] In another aspect, there is provided pre-treatment screening assembly comprising a spillbox feed tank defining a tank cavity and comprising a tailings inlet for receiving a tailings fluid flow into the tank cavity; a screening device comprising a screening surface receiving the tailings fluid flow spilling from the spillbox feed tank, the screening surface being configured to allow material smaller than a predetermined size that is included in the tailings fluid flow to flow through the screening surface and separate coarse debris larger than or equal to the predetermined size from the tailings fluid flow, thereby separating the tailings fluid into a coarse debris fraction and a screened tailings fluid; and a collector body defining a collecting cavity and arranged below the screening surface of the screening device, the collector body comprising a sand discharge opening formed in a bottom portion of the collector body for collecting and periodically removing sand accumulated in the collector body.

[0035] In another aspect, there is provided pre-treatment screening assembly comprising: a screening device comprising a screening surface receiving a tailings fluid flow, the screening surface being configured to allow material smaller than a predetermined size that is included in the tailings fluid flow to flow through the screening surface and separate coarse debris larger than or equal to the predetermined size from the tailings fluid flow, thereby separating the tailings fluid into a coarse debris fraction and a screened tailings fluid; and a collector body arranged below the screening surface of the screening device and defining a collecting cavity to receive the screened fluid, the collector body comprising: a tailings discharge outlet for discharging the screened tailings fluid from the collecting cavity; and a deflector plate arranged in the collecting cavity forming a barrier between inflow off the screening device and the tailings discharge outlet.

[0036] In another aspect, there is provided a pre-treatment screening assembly comprising: a spillbox feed tank defining a tank cavity and comprising a tailings inlet for providing a tailings fluid flow into the tank cavity; a screening device having a screening surface receiving the tailings fluid flow from the spillbox feed tank, the screening surface being configured to allow material smaller than a predetermined size that is included in the tailings fluid flow to flow through the screening surface and separate coarse debris larger than or equal to the predetermined size from the tailings fluid flow, thereby separating the tailings fluid into a coarse debris fraction and a screened tailings fluid; a collector body arranged below the screening surface of the screening device to receive the screened tailings fluid; and a frame supporting the spillbox feed tank, the screening device and the collector body and configured such that the spillbox feed tank, the screening device and the collector body are spaced apart from a ground surface on which the frame rests.

[0037] In another aspect, there is provided a pre-treatment screening assembly comprising: a plurality of spillbox feed tanks, each spillbox feed tank defining a tank cavity and comprising a tailings inlet for providing a tailings fluid flow into the tank cavity; at least two screening devices, each screening device defining a longitudinal direction and having two opposed longitudinal ends, said at least two screening devices extending side to side substantially parallel, and each screening device having a screening surface receiving the tailings fluid flow from the spillbox feed tanks, the screening surface being configured to allow material smaller than a predetermined size that is included in the tailings fluid flow to flow through the screening surface and separate coarse debris larger than or equal to the predetermined size from the tailings fluid flow, thereby separating the tailings fluid into a coarse debris fraction and a screened tailings fluid; an access platform extending along the screening devices at one of their longitudinal ends; and a collector body arranged below the screening surface of the screening devices to receive the screened tailings fluids.

[0038] In another aspect, there is provided a pre-treatment facility comprising: a pre-treatment screening assembly according to the present disclosure; an inlet line fluidly connected to the pre-treatment screening assembly to discharge a tailings fluid flow onto the screening surface of the screening device; and a discharge line fluidly connected to the collector body for downstream treatment operations of the screened tailings fluid.

[0039] In another aspect, there is provided a process for screening coarse debris from a tailings fluid flow provided by an inlet line, the process comprising: providing the tailings fluid flow to a pre-treatment screening assembly comprising a spillbox feed tank, a screening device and a collector body, the spillbox feed tank defining a tank cavity and comprising a bottom wall; filling the tank cavity of the spillbox feed tank with the tailings fluid flow through a tailings inlet formed in the bottom wall of the spillbox feed tank so as to form in the tank cavity a substantially vertical tailings fluid inlet flow; discharging a tailings fluid outlet flow from the tank cavity onto the screening device, the screening device having a screening surface configured to allow material smaller than a predetermined size that is included in the tailings fluid flow to flow through the screening surface and separate coarse debris larger than or equal to the predetermined size from the tailings fluid flow, thereby separating the tailings fluid into a coarse debris fraction and a screened tailings fluid; and collecting the screened tailings fluid into the collector body.

[0040] In another aspect, there is provided a process for screening coarse debris from a tailings fluid flow provided by an inlet line, the process comprising: providing the tailings fluid flow to a pre-treatment screening assembly comprising a spillbox feed, a screening device and a collector body, the spillbox feed tank defining a tank cavity; filling the tank cavity of the spillbox feed tank with the tailings fluid flow through a tailings inlet provided above an upper portion of the tank cavity for discharging downwardly the tailings fluid flow into the tank cavity; discharging a tailings fluid outlet flow from the tank cavity onto the screening device, the screening device having a screening surface configured to allow material smaller than a predetermined size that is included in the tailings fluid flow to flow through the screening surface and separate coarse debris larger than or equal to the predetermined size from the tailings fluid flow, thereby separating the tailings fluid into a coarse debris fraction and a screened tailings fluid; and collecting the screened tailings fluid into the collector body.

[0041] In another aspect, there is provided a process for screening coarse debris from a tailings fluid flow provided by an inlet line, the process comprising: providing the tailings fluid flow to a pre-treatment screening assembly comprising a spillbox feed tank defining a tank cavity, a screening device and a collector body; filling the tank cavity of the spillbox feed tank with the tailings fluid flow through a tailings inlet formed in the spillbox feed tank; discharging a tailings fluid outlet flow from the tank cavity onto the screening device, the screening device having a screening surface configured to allow material smaller than a predetermined size that is included in the tailings fluid flow to flow through the screening surface and separate coarse debris larger than or equal to the predetermined size from the tailings fluid flow, thereby separating the tailings fluid into a coarse debris fraction and a screened tailings fluid; collecting the screened tailings fluid into the collector body; and removing the coarse debris from the screening surface.

[0042] In another aspect, there is provided process for screening coarse debris from a tailings fluid flow provided by an inlet line and going into a discharge line, the process comprising: providing the tailings fluid flow to a pre-treatment screening assembly comprising a spillbox feed tank defining a tank cavity, a screening device and a collector body having a discharge outlet connected to the discharge line; filling the tank cavity of the spillbox feed tank with the tailings fluid flow through a tailings inlet formed in the spillbox feed tank; discharging a tailings fluid outlet flow from the tank cavity onto the screening device, the screening device having a screening surface configured to allow material smaller than a predetermined size that is included in the tailings fluid flow to flow through the screening surface and separate coarse debris larger than or equal to the predetermined size from the tailings fluid flow, thereby separating the tailings fluid into a coarse debris fraction and a screened tailings fluid; collecting the screened tailings fluid into the collector body; and deflecting the screened tailings fluid inlet flow filling the collector body from the discharge outlet.

[0043] In another aspect, there is provided a process for screening coarse debris from a tailings fluid flow provided by an inlet line and going into a discharge line, the process comprising: providing the tailings fluid flow to a pre-treatment screening assembly comprising a spillbox feed tank defining a tank cavity, a screening device and a collector body having a discharge outlet connected to the discharge line; filling the tank cavity of the spillbox feed tank with the tailings fluid flow through a tailings inlet formed in the spillbox feed tank; discharging a tailings fluid outlet flow from the tank cavity onto the screening device, the screening device having a screening surface configured to allow material smaller than a predetermined size that is included in the tailings fluid flow to flow through the screening surface and separate coarse debris larger than or equal to the predetermined size from the tailings fluid flow, thereby separating the tailings fluid into a coarse debris fraction and a screened tailings fluid; collecting the screened tailings fluid into the collector body; and removing sand accumulated in the collector body.

[0044] In another aspect, there is provided a process for screening coarse debris from a tailings fluid flow coming from an inlet line, the process comprising: providing the tailings fluid flow to a pre-treatment screening assembly comprising a plurality of spillbox feed tanks with a tank cavity, a screening device, a collector body and a plurality of overflow weirs extending outwardly from an upper portion of a respective one of the tank cavities; filling each tank cavity of the spillbox feed tanks with the tailings fluid flow through a tailings inlet formed in each of the spillbox feed tanks for the tailings fluid flow to reach an overflow weir extending from a respective one of the spillbox feed tanks; discharging a tailings fluid outlet flow over the overflow weir of the tank cavity onto the screening device, the screening device having a screening surface configured to allow material smaller than a predetermined size that is included in the tailings fluid flow to flow through the screening surface and separate coarse debris larger than or equal to the predetermined size from the tailings fluid flow, thereby separating the tailings fluid into a coarse debris fraction and a screened tailings fluid; collecting the screened tailings fluid into the collector body; and adjusting the outflow rate of at least one of the tailings fluid outlet flow for the plurality of spillbox feed tanks to have a substantially similar outlet flow rate.

[0045] In another aspect, there is provided a -treatment screening facility, comprising: a plurality of pre-treatment screening assemblies according to the present disclosure; a plurality of adjustable inlet valves configured to adjust the tailings inlet flow in a respective one of the spillbox feed tanks; the adjustable inlet valves being adjustable for the respective spillbox feed tanks to provide a substantially similar outlet flow into each spillbox feed tank.

[0046] In another aspect, there is provide a pre-treatment screening facility, comprising: a pre-treatment screening assembly according to the present disclosure; an inlet line fluidly connected to the pre-treatment screening assembly to discharge a tailings fluid flow onto the screening surface of the screening device; and a discharge line fluidly connected to the collector body for downstream treatment operations of the screened tailings fluid.

[0047] The pre-treatment screening assembly according to the present disclosure is thus particularly advantageous in that, among other advantages that will be detailed in the following description, the screening capacity is improved, the losses of tailings fluid are reduced, the screened tailings fluid are efficiently removed from a collecting cavity of the assembly, the coarse debris received and retained by the assembly are efficiently removed and the debris are prevented from settling in the collecting cavity. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] Figs. 1 and 2 are respectively front and rear perspective views of a first implementation of a pre-treatment screening assembly, the pre-treatment screening assembly comprising spillbox feed tanks for receiving a tailings fluid flow, screening devices receiving the tailings fluid flow from the spillbox feed tanks and separating the tailings fluid into a coarse debris fraction and a screened tailings fluid, and collector bodies receiving the screened tailings fluid;

[0049] Fig. 3 is a front elevation view of the pre-treatment screening assembly of Fig. 1;

[0050] Fig. 4 is a side elevation view of the pre-treatment screening assembly of Fig. 1

[0051] Figs. 5 and 6 are respectively front and rear perspective views of a second implementation of a pre-treatment screening assembly comprising spillbox feed tanks, screening devices and collector bodies;

[0052] Fig. 7 is a cross-section view of a third implementation of a pre-treatment screening assembly, the pre-treatment screening assembly further comprising a debris collection bin;

[0053] Fig. 8 is an elevation view of an implementation of a spillbox feed tank;

[0054] Fig. 9 is an elevation view of another implementation of a spillbox feed tank;

[0055] Fig. 10 is a side elevation view of an implementation of a spillbox feed tank and a screening device;

[0056] Fig. 11 is a cross-section view of an implementation of a screening device;

[0057] Fig. 12 is a cross-section view of another implementation of a screening device, a mechanical cleaning device being mounted to the screening device;

[0058] Fig. 13 is front perspective view of the screening device of the pre- treatment screening assembly of Fig. 1, the screening device having a screening surface with an adjustable inclination angle;

[0059] Fig. 14 is a rear perspective view of the screening device of Fig. 13;

[0060] Fig. 15 is a side elevation view of the screening device of Fig. 13;

[0061] Fig. 16 is a top plan view of the screening device of Fig. 13;

[0062] Fig. 17 is a cross-section view of a bottom portion of an implementation of a collector body comprising a bottom discharge opening;

[0063] Fig. 18 is a rear perspective view of the collector body of the pre-treatment screening assembly of Fig. 1;

[0064] Fig. 19 is a top plan view of the collector body of Fig. 18;

[0065] Fig. 20 is a cross-section view of the collector body of Fig. 18;

[0066] Fig. 21 is a rear perspective view of a vortex breaker;

[0067] Fig. 22 is a cross-section view of the vortex breaker of Fig. 21;

[0068] Fig. 23 is a schematic view of an implementation of a pre-treatment site; and

[0069] Fig. 24 is a schematic view of another implementation of a pre-treatment site. DETAILED DESCRIPTION

[0070] Systems, processes, devices and techniques are described that allow pre- treating oil sands fine tailings in order to remove coarse debris prior to a chemical tailings treatment operation, such as chemical enhanced dewatering or other processes.

[0071] There are provided pre-treatment screening techniques for removing coarse debris from oil sands fine tailings and produce screened oil sands fine tailings, the screened oil sands fine tailings having improved reactivity and / or mixability with chemicals in a subsequent chemical tailings treatment operation. The pre-treatment screening techniques can further produce screened oil sands fine tailings thereby enabling to reduce or eliminate damage, clogging and / or plugging of downstream equipment used in the chemical tailings treatment operation. General pre-treatment screening assembly

[0072] Pre-treatment screening assemblies can be configured for receiving debris containing oil sands fine tailings and for removing coarse debris from an oil sands fine tailings fluid. The oil sands fine tailings are for instance retrieved from a tailings pond. An oil sands fine tailings fluid that is pumped from the tailings pond by means of a dredge or barge typically includes various kinds of debris.

[0073] Figs. 1 to 4 represent a first implementation of the pre-treatment screening assembly 100. Figs. 5 and 6 represent a second implementation of the pre-treatment screening assembly 100, whereas Fig. 7 represents a third implementation. Referring to the first implementation of Figs. 1 to 7, the pre-treatment screening assembly 100 can include a frame 102, at least one spillbox feed tank 110, at least one screening device 140 in fluid communication with the spillbox feed tank 110 and at least one collector body 160. In the implementation shown, the spillbox feed tank 110, the screening device 140 and the collector body 160 are mounted to the frame 102. In other implementations, at least one of the spillbox feed tank 110, the screening device 140 and the collector body 160 can sit directly on a ground surface.

[0074] As represented for instance in Figs. 6 and 7, the oil sands tailings fluid is fed to the pre-treatment screening assembly 100 through an inlet line 104, which is connected to the spillbox feed tank 110. The spillbox feed tank 110 then discharges the tailings fluid onto the screening device 140. The screening device 140 has a screening surface 142 that is configured to separate coarse debris from the tailings fluid, thereby producing a screened tailings fluid which flows through the screening surface 142 and coarse debris that are retained by the screening surface 142. The screened tailings fluid is collected by the collector body 160. The screened tailings fluid can contain material with a predetermined size enabling the material to flow through the screening surface 142 of the screening device 140 toward and into the collector body 160. The screened tailings fluid collected in the collector body 160 can then be sent to a discharge line 108 for downstream chemical tailings treatment operations that can include, for instance but without being limitative, coagulation and / or flocculation and dewatering.

[0075] Some improvements relative to the different components of the pre- treatment screening assembly 100 will now be described; the improvements can either be considered separately or be combined together. Spillbox feed tank implementations

[0076] Referring now more particularly to Figs. 8 to 10, the spillbox feed tank 110, which is configured to feed the oil sands fine tailings fluid to the screening device 140, includes a tailings inlet 112, a tank cavity 114 defined by side walls 116 and a bottom wall 118, and an overflow weir 120. The oil sands fine tailings fluid is fed into the tank cavity 114 via the tailings inlet 112 and flows upward into the tank cavity 114 until reaching the overflow weir 120, at which point the tailings fluid flows over the overflow weir 120 and down onto the screening device 140. Tailings inlet

[0077] In the example implementation of the spillbox feed tank 110 from Fig. 9, the tailings inlet 112 is formed in the bottom wall 118, for example substantially centrally. In the existing spillbox feed tank 110' represented for instance in Fig. 8, the tailings inlet 112' is formed in one of the side walls 116' of the spillbox feed tank 110' so that, when a tailings fluid flow is introduced into the tank cavity 114' via the tailings inlet 112', the tailings fluid flow rebounds on the side wall opposed to the one in which the tailings inlet 112' is formed. This existing spillbox feed tank geometry creates an uneven flow distribution across the screening surface of the screening device when the tailings fluid flows over the overflow weir onto the screening surface. Such an arrangement of the tailings inlet 112' can lead to an overload of one side of the screening surface, resulting in high losses of the fine tailings fluid running off of the screening device on this side.

[0078] On the contrary, in the spillbox feed tank 110 represented in Fig. 9, in which the tailings inlet 112 is formed in the bottom wall 118 of the spillbox feed tank 110, for instance centrally in the bottom wall 118, the flow bias is significantly reduced in comparison with the spillbox feed tank 110' of Fig. 8, resulting in an improved screening of the tailings fluid. In the spillbox feed tank of Fig. 9, the tailings fluid defines a substantially vertical flow in the tank cavity 114 when introduced therein via the tailings inlet 112. The tailings fluid can then be discharged uniformly onto the screening surface 142 of the screening device 140. As a result, the used surface area of the screening surface 142 is increased in comparison with the spillbox feed tank 110' of Fig. 8, the tailings fluid overflow is reduced and thus the screening capacity of the pre- treatment screening assembly 100 comprising the spillbox feed tank 110 of Fig. 9 is improved in comparison with a pre-treatment screening assembly comprising the spillbox feed tank 110' of Fig. 8.

[0079] Referring to Fig. 6, another implementation of the inlet line 104 is disclosed. In the implementation shown, the pre-treatment screening assembly 100 comprises four spillbox feed tanks 110 arranged by pairs and spilling the oil sands tailings fluid on two screening devices 140. Unlike the spillbox feed tanks 110 represented in Figs. 8 and 9 in which the oil sands tailings fluid forms a vertically rising fluid flow in the tank cavity 114, in the implementation represented in Fig. 6, the tailings inlet 112 comprises a substantially horizontally extending distribution pipe 117. The distribution pipe 117 extends above one of the pairs of spillbox feed tanks 110 and comprises, in the implementation shown, two opposed longitudinal outlets 115 for the oil sands tailings fluid to be discharged downwardly into each one of pair of spillbox feed tank 110. In other words, the tailings inlet 112 is provided above an upper portion of the tank cavity 114. The inlet distribution pipe 117 extends substantially horizontally above the upper portion of the tank cavity 114. This substantially horizontal arrangement of the tailings inlet 112 limits the risk that coarse debris settle and plug the tailings inlet 112 of the spillbox feed tank 110. In the implementation shown, the pre-treatment screening assembly 100 further comprises two spaced apart vertically extending distribution pipes 105 fluidly connecting the inlet line 104 and the tailings inlet 112. Dimensions of the overflow weir being narrower than dimensions of the screening surface

[0800] As represented for instance in Fig. 7, the screening device 140 has an upstream inlet 144, the tailings fluid flow being discharged onto the screening surface 142 of the screening device 140 over the overflow weir 120 of the spillbox feed tank 110 at the upstream inlet 144.

[0081] As represented for instance in Fig. 10, the screening device 140 has a plurality of substantially parallel screening bars that are spaced apart from each other so as to define openings on either side of each screening bar. The screening device 140 also includes a plurality of supporting bars forming boundaries of the screening surface 142. The supporting bars are arranged so that the screening surface 142 of the screening device 140 is substantially rectangular and defines a length L1 and a width L2, whereas the overflow weir 120 of the spillbox feed tank 110 defines a width W, as it is represented for instance in Fig. 10.

[0082] In some existing implementations of the pre-treatment screening assembly, the width of the overflow weir substantially corresponds to the width of the screening surface, so that a significant quantity of the tailings fluid that is discharged from the spillbox feed tank on the screening device is in fact discharged on the supporting bars of the screening device, and thus is discharged outside the screening surface, i.e. outside the collector body 160. This results in significant amounts of the tailings fluid that are not screened by the pre-treatment screening assembly.

[0083] In the shown implementation, as represented for instance in Fig. 10, the overflow weir 120 is dimensioned so that its width W is narrower than the width L2 of the screening surface 142. To this end, baffle plates 124 can be arranged in the tank cavity 114 of the spillbox feed tank 110, substantially parallel to the side walls 116, so as to the reduce the width W of the overflow weir 120 over which the tailings fluid is discharged at the upstream inlet 144 of the screening device 140 and to direct the tailings fluid flow towards the overflow weir 120. In the shown implementation, two baffle plates extend in the tank cavity, but it could also be conceived one single baffle plate extending in the tank cavity to direct the tailings fluid flow towards the overflow weir 120.

[0084] In some implementations, the width W of the overflow weir 120 represents less than about 90% of the width L2 of the screening surface 142. In some other implementations, the width W of the overflow weir 120 represents less than about 85% of the width L2 of the screening surface 142. In yet other implementations, the width W of the overflow weir 120 represents less than about 80% of the width L2 of the screening surface 142.

[0085] As the width W of the overflow weir 120 is reduced relative to the width L2 of the screening surface 142, the losses of the tailings fluid (i.e. the amount of the tailings fluid being discharged outside the screening surface 142 of the screening device 140, and thus outside the collector body 160) are reduced, and thus the capacity of the pre-treatment screening assembly 100 is increased compared to the pre-treatment screening assemblies in which the width of the overflow weir substantially corresponds to the width of the screening surface. Control and regulation devices

[0086] As detailed above, the tailings fluid is fed into the tank cavity 114 of the spillbox feed tank 110 via the tailings inlet 112 and then flows over the overflow weir 120 and down to the screening device 140 from the upstream inlet 144 (which corresponds to an upper edge of the overflow weir 120). Referring to Fig. 7, the pre- treatment screening assembly 100 can further comprise at least one adjustable valve 113 (or adjustable inlet valve) configured to adjust the tailings fluid inlet flow in the spillbox feed tank 110, for instance by cooperating with the tailings inlet 112. The spillbox feed tank 110 can further comprise a level sensor 126, as represented in Fig. 7, the level sensor 126 being configured to measure the tailings fluid level in the tank cavity 114 of the spillbox feed tank 110. In the implementation represented in Fig. 7, the adjustable inlet valve 113 is arranged in the vicinity of – proximate - the tailings inlet 112, but the adjustable valve 113 could be arranged elsewhere. For instance, the adjustable valve 113 could be arranged directly on the inlet line 104. In the implementation represented in Fig. 6, the adjustable valve could further be arranged, for instance and without being limitative, on the distribution pipe 117, or on the outlet 115. The pre-treatment screening assembly 100 could further comprise an adjustable valve (which can also be referred to as an adjustable outlet valve) mounted down the collector body 160 and cooperating with a discharge pump configured to make the screened tailings fluid circulate in the discharge line 108.

[0087] For instance and without being limitative, the level sensor 126 comprises two distinct pressure transmitters that are arranged in the tank cavity 114 and that measure the pressure of the tailings fluid at two distinct locations of the tank cavity 114. In another implementation, as represented in Fig. 1, the level sensor 126 can be arranged down a collecting cavity 166, for instance in a lower portion of the collector body 160. On the basis of a pressure difference between pressures measured by the two distinct pressure transmitters, the level sensor 126 determines the level of the tailings fluid in the tank cavity 114. For instance, the level sensor 126 can use the following principle: P=d*g*h, where P is the pressure difference between two vertical positions of a fluid, d is the density of the fluid, g is the gravitational constant and h is the distance between the two vertical positions at which the pressures of the fluid are measured, to determine the level of the tailings fluid in the tank cavity 114. Other implementations can be conceived to determine the level of the tailings fluid in the tank cavity 114. The adjustable valve 113 can then be actuated in response to the tailings fluid level determined by the level sensor 126.

[8800] For instance, when the level determined by the level sensor 126 is above a first pre-determined threshold, the adjustable valve 113 can be actuated to cooperate with the tailings inlet 112 so as to reduce the tailings fluid flow rate at the tailings inlet 112. To this end, the adjustable valve 113 can be designed to cooperate with a pump – or inlet pump - mounted in the inlet line 104 to feed the spillbox feed tank 110 with the tailings fluid.

[0089] On the other hand, when the tailings fluid level determined by the level sensor 126 is below a second pre-determined threshold, the adjustable valve 113 cooperating with the tailings inlet 112 can be actuated so as to increase the tailings fluid flow rate at the tailings inlet 112.

[0090] On the basis of the level measurements by the level sensor 126 (arranged for instance and without being limitative in the tank cavity 114 or in the collecting cavity 166), the adjustable valve 113 can also cooperate with transfer pumps (e.g., either inlet transfer pumps or outlet transfer pumps, depending on the location of the transfer pumps with regards to the inlet line 104 and the discharge line 108) of the pre- treatment screening assembly 100. For instance, when the tailings fluid level in the tank cavity and / or in the inlet line 104 and / or in the collecting cavity 166 is below a pre- determined threshold, the adjustable valve 113 can cooperate with the transfer pump configured to feed the spillbox feed tank 110 with the tailings fluid, for the transfer pump to speed up and / or for the adjustable valve 113 to open up, so as to increase the flow of the tailings fluid in the spillbox feed tank 110. Alternatively, when the tailings fluid level in the tank cavity 114 and / or in the inlet line 104 and / or in the collecting cavity 166 is above a pre-determined threshold, the adjustable valve 113 can cooperate with the transfer pump configured to feed the spillbox feed tank 110 with the tailings fluid, for the transfer pump to slow down and / or for the adjustable valve 113 to close up, so as to decrease the flow of the tailings fluid in the spillbox feed tank 110. The transfer pumps can be operated for instance to feed the spillbox feed tank 110 with the tailings fluid, to discharge the tailings fluid on the screening surface 142 of the screening device 140 or to make the screened tailings fluid circulate in the discharge line 108. It is understood that the level sensor 126 could also be configured to cooperate directly with any of the inlet and / or outlet transfer pumps, without cooperating with any adjustable valve 113. For instance, when the tailings fluid level in the tank cavity and / or in the inlet line 104 and / or in the collecting cavity 166 is below a pre-determined threshold, the level sensor 126 can cooperate with the outlet transfer pump configured to feed the discharge line 108 with the screened tailings fluid, for the outlet transfer pump to slow down, so as to decrease the flow of the screened tailings fluid in the discharge line 108. Alternatively, when the tailings fluid level in the tank cavity 114 and / or in the inlet line 104 and / or in the collecting cavity 166 is above a pre- determined threshold, the level sensor 126 can cooperate with the outlet transfer pump configured to feed the discharge line 108 with the screened tailings fluid, for the outlet transfer pump to speed up, so as to increase the flow of the screened tailings fluid in the discharge line 108. The level sensor 126 could also be configured to cooperate with an outlet adjustable valve to adjust the flow of the screened tailings fluid in the discharge line 108.

[0091] It is to be noted that, in some implementations, the frame 102 provides the pre-treatment screening assembly 100 with an elevated structure with regards to a ground surface supporting the screening assembly 100. In other words, the frame 102 is designed to space the spillbox feed tank 110, the screening device 140 and the collector body 160 from the ground surface. The frame 102 is thus configured to provide the different pumps of the assembly 100 with adequate suction pressure, in particular to ensure an efficient removal of the screened tailings fluid from the collector body 160. Screening device implementations

[0092] Referring again to Fig. 7, the tailings fluid is discharged from the spillbox feed tank 110 over the overflow weir 120 into the screening device 140 at the upstream inlet 144. The screening device 140 further comprises a bottom end 146, as represented for instance in Fig. 2. The bottom end 146 is designed to ease the removal of the coarse debris received and retained by the screening surface 142 towards a collection area 180. To enhance the removal of the coarse debris towards the collection area 180, the screening surface 142 can be inclined downwardly so as to define a first inclination angle a1 with respect to a horizontal direction; the first inclination angle a1 can range between about 25 degrees and about 45 degrees. For instance, the first inclination angle a1 measures about 30 degrees. Adjustable inclination of the screening surface

[0093] It should be noted that the first inclination angle a1 can be adjustable so as to adapt to the nature of the tailings to be screened or perform specific operational steps such as maintenance operations for instance. For instance, the screening device 140 is configured to have an operating mode as well as a cleaning mode in which the inclination angle a1 is adjustable. In the shown implementation, as represented for instance in Figs. 13 to 16, the pre-treatment screening assembly 100 further comprises a winch 148 that is configured to adjust the first inclination angle a1 formed by the screening surface 142 relative to the horizontal direction when the screening device 140 is configured in the cleaning mode. In the implementation shown, the winch 148 is configured to be manually actuated, but a pre-treatment screening assembly 100 having a motorized system configured to adjust the first inclination angle a1 of the screening surface 142 could also be provided. The pre-treatment screening assembly 100 could also comprise a plurality of interchangeable screening surfaces 142 each forming a different first inclination angle a1 with respect to a horizontal direction. As a result, it is possible to adapt the arrangement of the screening surface 142 of the screening device 140 so as to alternatively enable self-cleaning of the screening surface 142 or at least ease the discharging of the coarse debris from the screening surface 142 towards the collection area 180, or to reduce the tailings fluid losses resulting from a running off of the screening surface 142.

[0094] In other words, it is understood that the screening device 140 is designed to allow a user to reduce the first inclination angle a1 of the screening surface 142, if the coarse debris loading on the screening surface 142 is insufficient and / or if the tailings fluid losses are excessive. A user can also increase the first inclination angle a1 of the screening surface 142 so as to increase the self-cleaning of the screening surface 142, for instance under heavy debris loading or when it is considered that the amount of the coarse debris on the screening surface 142 has reached a pre-determined threshold.

[0095] The pre-treatment screening assembly can further comprise a sensor designed to evaluate the quantity of coarse debris on the screening surface. The pre- treatment screening assembly could further comprise a control circuit receiving a signal from the sensor when the quantity of coarse debris on the screening surface measured by the sensor has reached a pre-determined threshold, the control circuit then actuating the winch 148 as seen on Fig. 13 to 17 – or any other adapted mechanical device - so as to increase the value of the first inclination angle a1 formed between the screening surface and the horizontal direction.

[0096] The pre-treatment screening assembly could further comprise an additional sensor designed to evaluate the quantity of tailings fluid losses resulting from a running off of the screening surface; the control circuit could further be designed to receive a signal from the additional sensor when the quantity of tailings fluid losses has reached a pre-determined threshold, the control circuit then actuating the winch 148 as seen on Fig. 13 to 17 – or any other adapted mechanical device - so as to reduce the first inclination angle a1 formed between the screening surface and the horizontal direction.

[0097] In another implementation of the screening device 140 represented for instance in Fig. 11, the screening surface 142 could have a concave profile, thereby having a varying slope decreasing from a top end 147 of the screening device 140 to the bottom end 146 of the screening device 140. For instance, the angle formed between the screening surface 142 and the horizontal direction can vary between about 0 degree, at the bottom end 146 of the screening device 140, and about 80 degrees, at the top end 147 of the screening device 140.

[0098] The use of a concave profile for the screening surface 142 is particularly efficient for the automatic removal and / or accumulation of the coarse debris reaching the screening surface 142, without resulting from an increase of the tailings fluid losses resulting from a running off of the screening surface 142. Mechanical cleaning device

[0099] In some implementations, as represented in Fig. 12, the pre-treatment screening assembly 100 further comprises a mechanical cleaning device 170 that is configured to mechanically remove the coarse debris from the screening surface 142 of the screening device 140. The mechanical cleaning device 170 can regularly remove the coarse debris from the screening surface 142 and / or when the quantity of the coarse debris on the screening surface 142 has reached a pre-determined threshold. To this end, the mechanical cleaning device 170 can cooperate with the above- mentioned control circuit and be actuated in response to a signal sent by the above- mentioned sensor that is designed to evaluate the quantity of the coarse debris on the screening surface 142.

[00100] For instance and without being limitative, the mechanical cleaning device 170 comprises rakes and / or rotating brushes designed to go all over the screening surface 142 so as to pull the coarse debris away from the screening surface 142; for instance, the mechanical cleaning device 170 pulls the coarse debris toward the collection area 180.

[00101] In some implementations, as represented in Fig. 12, the screening device 140 comprises an upper portion 150 having an upper screening surface 151, and a lower portion 152 having a lower screening surface 153. The upper screening surface 151 defines an upper angle a2 with the horizontal direction and the lower screening surface 153 defines a lower angle a3 relative to the horizontal, the upper angle a2 being greater than the lower angle a3. In some implementations, the upper angle a2 can be between about 30 degrees and about 60 degrees, and the lower angle a3 can be between about 15 degrees and about 30 degrees. Optionally, the upper angle a2 can be between about 40 degrees and about 50 degrees, and the lower angle a3 can be between about 20 degrees and about 25 degrees. In some implementations, the upper angle a2 can be at least about 1.5 times greater than the lower angle a3. Optionally, the upper angle a2 can be about two times greater than the lower angle a3.

[00102] The arrangement of the upper and lower portions 150, 152 of the screening device 140 enables to efficiently separate the liquids from the coarse debris of the tailings fluid, and to direct the coarse debris towards the lower portion 152, so as to ease their removal from the screening device 140.

[00103] As represented in Fig. 12, the mechanical cleaning device 170 can be arranged on the lower portion 152 of the screening device 140, so that the dimensions of the mechanical cleaning device 170 are reduced with regards to a screening device 140 having one single inclination angle relative to the horizontal direction, in which case the mechanical cleaning device 170 would be dimensioned to go all over the screening surface 142.

[00104] As represented for instance in Fig. 12, the mechanical cleaning device 170 can comprise at least one rake 171 to remove coarse debris from the lower screening surface 153 of the lower portion 150. The rake 171 can be mounted on a caterpillar 191 to automatically remove coarse debris from the screening surface 142 of the screening device 140.

[00105] The mechanical cleaning device 170 can further comprise a shaker (not illustrated in Fig. 12) designed to make the screening surface 142 vibrate so as to more easily accumulate the coarse debris, and then to more easily remove them. Debris collection bin

[00106] In some existing implementations of the pre-treatment screening assembly, the coarse debris that are removed from the screening device are rejected in the tailings pond. However, such a coarse debris management requires in particular from the screening device to be close to the tailings pond.

[00107] As it is represented for instance in Fig. 7, the pre-treatment screening assembly 100 can further comprise a debris collection bin 172 that is placed, for instance and without being limitative, under, beside or in the vicinity of the screening device 140, so as to collect the coarse debris that are removed from the screening surface 142, for instance by the above described mechanical cleaning device 170. The debris collection bin 172 can also be configured to collect at least partially a tailings fluid loss resulting from a tailings running off of the screening surface. The coarse debris that are collected in the debris collection bin 172 can then be hauled away at an appropriate dump location, so as to permanently be removed from the tailings pond 202 and to reduce their long-term impact on the tailings fluid dredging. The dimensions of the debris collection bin 172 are adapted so that the debris collection bin 172 will only need to be emptied, for instance, a few times a month.

[00108] Still referring to Figure 7, the pre-treatment screening assembly 100 can also comprise a debris heater 173 designed to heat the debris collection bin 172 so that its content will not freeze, which would make it more complex for the coarse debris to be removed from the debris collection bin 173. As mentioned above, the debris collection bin 172 can also be configured to at least partially collect tailings fluid overflow resulting from tailings running off of the screening surface. The pre-treatment screening assembly 100 can further comprise a debris collection pump mounted to an end of a pipe 174 extending partially in the debris collection bin 173, as represented in Fig. 7, that is designed to pump the tailings fluid loss from the debris collection bin 172 and to inject them back into the spillbox feed tank 110. The debris collection bin 172 and the debris collection pump 174 enable to increase the quantity of the tailings fluid that is processed by the pre-treatment screening assembly 100. Moreover, the use of the debris collection bin 172 enables to reduce constraints relative to the location of the screening device 140 close to the tailings pond 202, for debris removal purposes. Collector body implementations

[00109] As mentioned above, after the oil sands fine tailings fluid has been discharged at the upstream inlet 144 of the screening device 140, the screened oil sands fine tailings fluid is collected by the collector body 160.

[00110] The collector body 160 can be sized and configured to enable the flow of the screened tailings fluid to accumulate and form a more uniform composition of the screened tailings. Thus, for instance, fluctuations in the composition of the tailings retrieved from the tailings pond 202 can be attenuated both by the removal of the coarse debris via the screening device 140 and also by the accumulation of the screened tailings fluid having greater uniformity than the tailings fluid piped from the tailings pond.

[00111] In the shown implementation, the collector body 160 has side walls 162 and a bottom wall 164 that define together a collecting cavity 166.

[00112] In the implementation shown in Figs. 1 to 4 and Fig. 19, the pre-treatment screening assembly 100 further comprises two overflow weirs 60 located at opposed longitudinal ends of the collector body 160. The overflow weirs 60 are designed to collect screened tailings fluid overflowing from the collector body 160. The overflow weirs 60 comprise an overflow outlet 62, for the tailings fluid to be removed from the overflow weirs 60. Design of the collector body

[00113] As represented for instance in Figs. 2 and 17, the bottom wall 164 of the collector body 160 can comprise a bottom discharge opening 165 - or sand discharge opening - designed to easily remove debris, such as sand particles, that build up or accumulate in the collector body 164 and that have not been removed by the screening device 140. In the implementation shown, the discharge opening 165 is formed in a side wall 162 of the collector body 160 opposed to the side wall 162 in which the discharge outlet 167 is formed. In some implementations, debris is removed from the collector body 160 via the bottom discharge opening 165 using, for instance, a pump fluidly connected to the collecting cavity 166 of the collector body 160.

[00114] In some other implementations, as represented in Figs. 1 to 4, the pre- treatment screening assembly 100 further comprises a flushing inlet nozzle 50, for instance formed in a side wall 62 opposed to the one in which the bottom discharge opening 165 is formed. Flush water can thus circulate in the collecting cavity 166, in a bottom portion thereof, from the flushing inlet nozzle 50 towards the bottom discharge opening 165, so as to push debris towards the bottom discharge opening 165 and remove the debris from the collector body 160 via the bottom discharge opening 165, thus preventing the debris from settling in the bottom portion of the collecting cavity 166. The bottom discharge opening 165 thus forms a flushing outlet of the collector body 160. It is appreciated that the shape, the configuration and the location of the bottom discharge openings 165, as well as the shape, the configuration and the location of the flushing inlet nozzles 50 can vary from the implementation shown. The pressure of the flushing water can also be adapted to the dimensions of the collector body 160, and to the debris having to be removed therefrom.

[00115] The collector body 160 can be designed to direct the debris towards the bottom discharge opening 165, in order to ease their removal outside the collector body 160. The collector body 160 can therefor have a bottom conical shape or, as represented for instance in Fig. 20, at least one sloped side wall 163 extending from one of the side walls 162 and being designed to direct debris towards the bottom discharge opening 165. For instance, the sloped side wall 163 starts midway up the side wall 162 of the collector body 160 opposite the side wall 162 in which the discharge outlet 167 is formed, and slopes downwardly towards the discharge outlet 167. As represented in Fig. 20, the sloped side wall 163 can extend between one of the side walls 162 and the bottom wall 164. Air reduction in the screened tailings

[00116] Referring to Fig. 2, the screened tailings fluid collected in the collecting cavity 166 of the collector body 160 is then released from the collector body 166 through at least one discharge outlet 167 that can be located in the bottom wall 164 or in a bottom portion of one of the side walls 162 of the collector body 160 and connected to the discharge line 108. The discharge line 108 then sends the screened tailings fluid to further treatments, such as flocculation and dewatering of the screened tailings. The pre-treatment screening assembly 100 comprises at least one discharge pump 109 to make the screened tailings fluid circulate in the discharge line 108.

[00117] In some pre-treatment screening assemblies, air can be trapped within the screened tailings fluid flow, when the screened tailings fluid falls through the screening device. The formed air pockets sometimes disrupt operation of the pre-treatment screening assembly, for instance by disrupting the working of the discharge pump.

[00118] So as to reduce the negative impact of the air mixing on the pre-treatment of the tailings, as represented in Figs. 1, 2 and 7, the discharge outlet 167 can be arranged in one of the side walls 162 of the collector body 160 that extends perpendicularly to the upstream inlet 144 of the screening device 140 and perpendicularly to the width L2 of the screening surface 142.

[00119] The upstream inlet 144 of the screening device 140 and the discharge outlet 167 of the collector body 160 can be arranged on a same side of the collector body 160 (i.e., so as to be spaced apart from each other, the upstream inlet 144 being directly vertically above the tailings discharge outlet 167). In other words, the tailings fluid is discharged at the upstream inlet 144 in a first direction and the screened tailings fluid is discharged at the tailings discharge outlet 167 in a second direction opposed to the first direction. As the tailings fluid passes through the screening surface 142, the tailings fluid can plummet substantially vertically into the collector body 160 directly above the discharge outlet 167. As that plummeting fluid hits the tailings fluid level in the collector body 160, the tailings fluid can entrain air into the collector body liquid phase (like a waterfall), which can then increase the risk of short circuiting to the discharge outlet 167 directly below and on same side. The pre-treatment screening assembly 100 can thus further comprise at least one deflector plate 168 arranged in the collecting cavity 166 of the collector body 160, for instance above the discharge outlet 167, as represented for instance in Figs. 19 and 20. The deflector plate 168 provides a barrier between inflow off the screening device 140 and the discharge outlet 167 of the collector body 160 to limit the risk of tailings fluid inflow short circuiting to the discharge outlet 167 and carrying air with it. In other words, the deflector plate 168 creates a path of travel for the tailings fluid in the collector body 160 that increases retention time for a particle of fluid allowing more time for air to rise to surface and dissipate instead of being pulled into the discharge outlet 167 and entrained in the discharge line 108.

[00120] In the implementation represented, the deflector plate 168 is oriented at an inclination angle a4 with respect to the horizontal direction. In an implementation, the inclination angle a4 is between about 15 degrees and about 75 degrees. Optionally, the inclination angle a4 is between about 30 degrees and about 60 degrees. Further optionally, the inclination angle a4 is between about 40 degrees and about 50 degrees.

[00121] In some other implementations, as represented for instance in Figs. 20, the sloped deflector plate 168 extends only partially between two opposed side walls 162 of the collector body 160, a substantially horizontal portion 169 extending between the deflector plate 168 and the side wall 162 opposed to the one from which the deflector plate 168 extends.

[00122] As represented in Figs. 20 to 22, the pre-treatment screening assembly 100 can further comprise a vortex breaker 161 mounted into the discharge outlet 167 of the collector body 160 and extending at least partially in the collecting cavity 166.

[00123] As represented for instance in Figs. 21 and 22, the vortex breaker 161 comprises a substantially cylindrical body 190 and a vortex breaking core 192 arranged in the cylindrical body 190. In the shown implementation, the vortex breaking core 192 has a crossed-shaped section: the vortex breaking core 192 comprises two plates 194, 195 assembled together in a substantially perpendicular way, the two plates 194, 195 being secured to the cylindrical body 190. Pre-treatment screening assembly implementations

[00124] It should be understood that the present description is not limited to a pre- treatment screening assembly 100 comprising solely one spillbox feed tank 110, one screening device 140 and one collector body 160, the different elements being mounted to the frame 102.

[00125] Indeed the pre-treatment screening assembly 100 can include a plurality of screening devices mounted adjacently and operating in parallel with respect to each other.

[00126] As represented for instance in Figs. 1 to 4, the pre-treatment screening assembly 100 can include four spillbox feed tanks 110, each spillbox feed tank 110 having an overflow weir 120 for discharging a tailings fluid flow on a corresponding screening device 140.

[00127] The pre-treatment screening assembly 100 can have one single collector body 160 arranged below the different screening devices 140, or there can be one or more collector bodies 160 for each overlying screening device 140.

[00128] In the implementation of the pre-treatment screening assembly 100 comprising a plurality of collector bodies 160, each collector body can have a discharge outlet 167, or the pre-treatment screening assembly 100 can have a possibly larger single discharge outlet 167. It is thus possible to form the single discharge outlet 167 in one of the side walls 162 or bottom walls 164 of the collector bodies 160 so as to adapt the pre-treatment screening assembly 100 to the location where it is installed. Optimization of the pre-treatment screening assembly design

[00129] As represented in Figs. 1 to 6, in order to improve the operation of the pre- treatment screening assembly 100, the assembly 100 can include platforms, stairways and railings 106 which allow an operator to easily and safely monitor the pre-treatment screening assembly 100, for example to monitor the screening surfaces 142.

[00130] In some implementations, as represented in Figs. 1 and 2, platforms 106 are arranged between two adjacent screening devices 140. As represented in Figs. 5 and 6, the pre-treatment screening assembly 100 can comprise one platform 106 extending along a longitudinal direction L of the pre-treatment screening assembly 100, and substantially perpendicularly to the length L1 of the screening devices 140.

[00131] This arrangement of the platform 106 enables to increase the dimensions of the screening surfaces 142 of the two adjacent screening devices 140 compared to an implementation wherein the pre-treatment screening assembly 100 includes platforms 106 which are arranged between two adjacent screening devices 140. Other arrangements of the platform 106 can be conceived within the framework of the present disclosure; for instance, the platform 106 can be arranged so as to overhang the screening devices 140.

[00132] As represented in Fig. 5, the pre-treatment screening assembly 100 can further comprise vertically extending paths 107, such as ladders, extending from the ground towards the platforms 106 surrounding or extending between or along the screening devices 140, for a user to easily and safely access the screening devices 140, when the frame 102 comprises an elevated structure. In the shown implementation, the paths 107 are mounted to the frame 102. The pre-treatment screening assembly 100 can further comprise intermediate platforms 103 for instance extending along the lower portion of the collector body 160, for a user to easily access, for instance and without being limitative, the discharge outlets 167 or the bottom discharge openings 165.

[00133] As represented in Figs. 1, 13 and 14, the screening devices 140 can comprise each an access door 157, for instance to let a user easily access the screening surface 142, to clean and / or repair it, whenever needed. In the implementation of the pre-treatment screening assembly 100 in which the platforms 106 are arranged between two adjacent screening devices 140, as represented in Figs. 1 and 2, the access doors 157 of the two adjacent screening devices usually face each other, on each side of the corresponding platform 106.

[00134] In the implementation of the pre-treatment screening assembly 100 comprising one single platform 106, as represented in Fig. 5, the access doors of the screening devices 140 can be arranged at a longitudinal end of the screening device 140 at which the sole platform 106 extends.

[00135] In the implementation of the pre-treatment screening assembly 100 in which the platforms 106 do not extend between two adjacent screening devices 140, the dimensions of the screening surfaces 142 of the screening devices 140 can be increased. The overall screening surface of the pre-treatment screening assembly 100 can thus be increased, and so is the pre-treatment capacity of the pre-treatment screening assembly 100.

[00136] As represented in Fig. 1, the pre-treatment screening assembly 100 can further have a manway 70 for instance formed in one of the side walls 162 of the collector body 160, to allow a user, for instance for maintenance and / or repair purposes, to access the collecting cavity 166. Plurality of adjustable overflow weirs

[00137] In the shown implementation from Figs. 1 and 2, the pre-treatment screening assembly 100 comprises a plurality of spillbox feed tanks 110, each of them having an overflow weir 120.

[00138] In some implementations, the overflow weirs 120 of the spillbox feed tanks 110 are adjustable and configured to ensure that the different spillbox feed tanks 110 of the pre-treatment screening assembly 100 have a substantially similar outlet flow that is discharged on the corresponding screening device 140. Indeed, the ground on which the pre-treatment screening assembly 100 is installed via the frame 102 can be uneven, either at the installation of the screening assembly 100, or over time. The inclination of the pre-treatment screening assembly 100 can result in pressure differentials between the tailings inlets 112 of different spillbox feed tanks 110 and between the discharge outlets 167 of the collector bodies 160. As a result, one of the screening devices 140 can lack tailings fluid, whereas another one of the screening devices 140 can be overflowed. To limit the tailings fluid flow differences between the different screening devices 140, the above-described adjustable valves 113 can be adjusted differently between the different screening devices 140, and / or the adjustable overflow weirs 120 can be adjusted according to an elevation of each spillbox feed tank 110 relative to the ground on which the frame 102 is located. In other words, the adjustable overflow weirs 120 enable to compensate for differences in the elevation of the different spillbox feed tanks 110 and to effectively re-establish a substantially similar level across all spillbox feed tanks 110.

[00139] The adjustability of the overflow weirs 120 can be implemented in different manners. For instance, the spillbox feed tanks 110 can have a mounting base 130, the spillbox feed tanks 110 being mounted to the frame 102 of the pre-treatment screening assembly 100 via their respective mounting base 130. The mounting base 130 can be adjustable so as to adjust the elevation of the overflow weir 120.

[00140] Alternatively, the overflow weirs 120 of the spillbox feed tanks 110 can comprise adjustable plates that are configured to modify the elevation at which the tailings fluid flow will flow out of the tank cavity 114 of the spillbox feed tank 110.

[00141] It is thus understood that the adjustable overflow weirs 120 of the spillbox feed tanks 110 allows to more evenly discharge the tailings fluid flow on the screening surface 142 of the different screening devices 140, thus improving the capacity and efficiency of the pre-treatment screening assembly 100. Pre-treatment site implementations

[00142] In another aspect, there is provided a pre-treatment site for the pre- treatment of fine tailings, comprising several pre-treatment screening assemblies arranged close to a tailings pond.

[00143] As represented in Fig. 23, an existing pre-treatment site 200' can include six pre-treatment screening assemblies 100', each of them having, for instance, four screening devices 140'. The four screening devices 140' of each pre-treatment screening assembly 100' are substantially parallel to each other so that each pre- treatment screening assembly 100' has a substantially rectangular shape with a long side I1' and a small side I2', the small side I2' of the assembly 100' corresponding substantially to a length of the screening devices 140.

[00144] Moreover, the six pre-treatment screening assemblies 100' of the pre- treatment site 200' represented in Fig. 23 are arranged side by side along their long side I1', so that the twenty-four screening devices 140 are arranged in a substantially parallel manner along the tailings pond 202. Optimized footprint pre-treatment site

[00145] The pre-treatment site 200 represented in Fig. 24 comprises, for instance, three pre-treatment screening assemblies 100, each of them having for instance four screening devices 140. Each pre-treatment screening assembly 100 has a substantially rectangular shape with a long side I1 and a short side I2, the four corners of the rectangular being constituted by the four screening devices 140.

[00146] The three pre-treatment screening assemblies 100 are arranged side by side, their long sides I1 being substantially parallel to each other.

[00147] The footprint of the pre-treatment site 200 represented in Fig. 24 is thus significantly reduced compared to the footprint of the existing pre-treatment site 200' as represented in Fig. 23. Furthermore, thanks to an increase of the efficiency of the pre- treatment screening assemblies 100, the efficiency of the disclosed pre-treatment site 200 of Fig. 24 is substantially identical or greater than the efficiency of the existing pre- treatment site 200' of Fig. 23.

[00148] Moreover, among many significant advantages, the reduced footprint of the pre-treatment site 200 compared to the pre-treatment site 200' of Fig. 23 enables to reduce the dimensions of the inlet line 104 of the different pre-treatment screening assemblies 100. Less collection areas 180 and / or less debris collection bins 172 for the collecting of the coarse debris are also required. It is appreciated that the location and the number of the pre-treatment screening assemblies 100 and / or the screening devices 140 of the pre-treatment site 200 can vary from the implementation shown. Method implementations

[00149] In another aspect, there is provided a method for screening debris from an oil sands fine tailings fluid to pre-treat the oil sands fine tailings fluid for chemical treatment, such as flocculation and dewatering. The oil sands fine tailings fluid comes from an inlet line 104. It is noted that the flocculation and dewatering can be performed using various methods. In one example, the screened tailings are subjected to in-line flocculation and are then transferred by pipeline to a deposition site that can include deposition cells in which the flocculated tailings are deposited in multiple thin lifts. The water drains away from the flocculated material to form a dewatered solid material. In another example, the screened tailings are subjected to in-line adding of an immobilization chemical and a flocculant to form a flocculated material that is then transferred by pipeline to a mine pit or similar containment structure where the solids settle to form a settled layer and the water forms a water cap thereby forming a permanent aquatic storage structure (PASS). Other chemical treatment and dewatering methods are also possible.

[00150] The pre-treatment screening is enabled by one or more of the above- described assemblies, systems and devices.

[00151] The method includes providing a spillbox feed tank 110 with a tailings fluid flow, the spillbox feed tank 110 having side walls 116 and a bottom wall 118 defining together a tank cavity 114, the spillbox feed tank 110 also comprising an overflow weir 120.

[00152] The method includes connecting the inlet line 104 to a tailings inlet 112 formed in the bottom wall 118 of the spillbox feed tank 110. For instance, the connection of the inlet line 104 to the tailings inlet 112 is configured to form a substantially vertical inlet flow in the tank cavity 114.

[00153] The method also includes feeding the spillbox feed tank 110 with the tailings fluid flow so that the tailings fluid flow reaches the overflow weir 120.

[00154] The method can further include adjusting at least one of the inlet and outlet flow rates of the tailings fluid flowing respectively to and from the spillbox feed tank 110. In other words, the method can further include adjusting the flow rate of the tailings fluid introduced into the tank cavity 114 via the tailings inlet 112 and / or of the tailings fluid going out of the tank cavity 114 when flowing over the overflow weir 120. It should be noted that the adjustment can be performed in response to different criteria, including a measured fluid level in the tank cavity 114, a fluid losses quantity of fluid resulting from a running off of the screening surface 142, a measured amount of coarse debris on the screening surface 142, etc.

[00155] The method can thus further include measuring a level of the tailing fluid in the tank cavity 114. Measuring can include sensing the level of the fed tailings with a level sensor. Measuring can also be performed differently; for example, it can be performed manually by an operator. Optionally, the level sensor can be operatively connected to a control circuit so as to monitor the level of tailings within the tank cavity 114 and / or within the collecting cavity 166 of the collector body 160 and actuate certain devices, such as valves (inlet and / or outlet valves) or inlet and / or outlet transfer pumps, to act in response to the sensed level when reaching given thresholds.

[00156] The modification of the inlet and / or outlet flow rates of the tailings fluid flow can be performed in response to the measured level of the tailings fluid in the tank cavity 114.

[00157] The method further comprises discharging the tailings fluid on a screening device 140, the tailings fluid being discharged over the overflow weir 120 and down to the screening device 140. The screening device 140 has a screening surface 142 configured to allow material with a predetermined size to flow through the screening surface 142 and separate the coarse debris, thereby splitting the tailings fluid into coarse debris and a screened tailings fluid. In some implementations, the method can include evenly discharging the tailings fluid flow along a width L2 of the screening device 140 so as to maximize a screening surface efficiency. Optionally, the method can include discharging the tailings fluid flow onto at most about 80% of the width of the screening surface 142. Further optionally, the method can include discharging the tailings fluid flow onto at most about 85% of the width screening surface 142. Still further optionally, the method can include discharging the tailings fluid flow onto at most about 90% of the width screening surface 142.

[00158] The method can further comprise removing the coarse debris from the screening surface 142.

[00159] As detailed above, the screening surface 142 is oriented at a first inclination angle a1 with respect to a horizontal direction. The method can further comprise adjusting the first inclination angle a1 of the screening surface 142.

[00160] The method can further comprise at least one of: - measuring an amount of coarse debris on the screening surface 142; measuring a fluid level in the tank cavity 114; and _ measuring an amount of tailings fluid losses resulting from a running off of the screening surface 142.

[00161] For instance, the first inclination angle a1 of the screening surface 142 can be modified in response to at least one of the measured amount of coarse debris, the measured fluid level in the tank cavity and the measured amount of tailings fluid losses.

[00162] The method can further comprise collecting the removed debris in a debris collection bin 172 which can be located near the screening device 140.

[00163] The method can further comprise heating the debris collected in the debris collection bin 172.

[00164] The method can further comprise pumping the tailings fluid contained in the debris collection bin 172 back into the spillbox feed tank 110, so as to reduce the amount of oil sands tailings fluid losses resulting from a running off of the screening surface 142. Depending on the time of the year, the pumping of the tailings fluid in the debris collection bin 172 can be performed with or without the heating of the debris collection bin 172.

[00165] The method can further comprise applying vibrations to the screening surface 142. Thanks to the vibrations, the coarse debris retained by the screening surface 142 can be more easily removed from the screening surface 142.

[00166] The method can further include collecting the screened tailings fluid in a collector body 160 prior to transporting the screened tailings fluid for chemical treatment via a discharge line 108. The collector body 160 can comprise a discharge outlet 167 connected to the discharge line 108.

[00167] The method can further include deflecting a screened tailings fluid flow upstream of the collector body 160 from the discharge outlet 167. Deflection can reduce the amount of air flowing with the screened tailings fluid flow in the discharge line 108.

[00168] The method can further comprise removing debris building up in the collector body 164. The method can comprise pumping the debris out of the collector body 164 via a bottom discharge opening 165 and / or flush watering the debris towards the bottom discharge opening 165 and circulating flush water in a bottom portion of the collecting cavity 166 from a flushing inlet nozzle 50 towards the bottom discharge opening 165.

[00169] The method can include providing a pre-treatment screening assembly 100 comprising at least two spillbox feed tanks 110 having each a tank cavity 114. The method can include adjusting the outflow rate of the tailings fluid flow discharged over the overflow weir 120 of at least one spillbox feed tank 110 of the different spillbox feed tanks 110 to have a substantially similar outlet flow rate between the different spillbox feed tanks 110.

[00170] Each overflow weir 120 defines a height relative to a ground on which the pre-treatment screening assembly 100 stands. The method can further comprise adjusting the height of at least one overflow weir 120 from the plurality of spillbox feed tanks 110 to obtain a substantially similar outlet flow rate between the different spillbox feed tanks 110.

[00171] Each spillbox feed tank 110 defines a height relative to a ground on which the pre-treatment screening assembly 100 stands. The method can further comprise adjusting the height of at least one spillbox feed tank 110 from the plurality of spillbox feed tanks 110 to have a substantially similar outlet flow rate between the spillbox feed tanks 110.

[00172] The steps of the method can be repeated or conducted for a plurality of pre-treatment screening assemblies 100 arranged in series or in parallel.

[00173] It should be understood that the pre-treatment screening techniques described herein provide screened tailings for improved and consistent mixing with chemicals in downstream tailings treatment operations.

[00174] In some implementations, the pre-treatment screening assembly removes coarse debris that would impede or inhibit chemical reactions, for instance flocculation reactions involving flocculant and fine solid particles in the tailings. The pre-treatment process can remove coarse debris having different chemical or inertial properties compared to the fine solid particles that are not removed.

[00175] In certain applications, the fine solid particles include clay and can have a certain shape, size and surface characteristics that are considered for the chemical selection and process design for the chemical treatment operation, and can bestow certain macroscopic fluid properties. In one example, the pre-treatment screening assembly can remove bitumen masses including slugs or mats that negatively affect anionic polymeric flocculant reactions with the fine solid particles in the tailings.

[00176] In some implementations, the pre-treatment screening assembly removes coarse debris that would have disrupted the mixing of the chemical additive and the fine tailings. For instance, the pre-treatment screening assembly can remove coarse debris that would impede consistent mixer performance or mixer flow regime. The pre- treatment screening assembly can also remove coarse debris that would cause two phase macroscopic fluid behaviour, thereby providing screened fine tailings having one phase macroscopic fluid behaviour. The pre-treatment screening assembly can remove coarse debris so that the resulting pre-treated tailings fluid is homogeneous, or does not contain a substantial amount of settling solid particles. The pre-treatment screening assembly can also remove coarse debris that would complicate or prevent reliable process modelling of the fluid mixing, flocculation or dewatering operations.

[00177] In some implementations, the pre-treatment screening assembly removes coarse debris that would damage or clog equipment.

[00178] While several implementations have been described and illustrated herein in relation to oil sands fine tailings, it should be understood that the processes, systems, devices and techniques can also be used for any other aqueous suspensions that include solid particles and coarse debris. Such aqueous suspensions can comprise mining tailings resulting from mining operations, such as mature fine tailings.

[00179] In the preceding description, the same numerical references refer to similar elements. Furthermore, for the sake of simplicity and clarity, not all figures contain references to all the components and features, and references to some components and features can be found in only one figure, and components and features of the present disclosure which are illustrated in other figures can be easily inferred therefrom.

[00180] Finally, while the description and drawings describe and illustrate certain implementations and examples of the pre-treatment techniques, the components, geometries, arrangements and / or configurations can have various other characteristics, features and co-operations as those presented herein.

[00181] Several alternative implementations have been described and illustrated herein. The implementations of the disclosure described above are intended to be exemplary only. A person of ordinary skill in the art would appreciate the features of the individual implementations, and the possible combinations and variations of the components. A person of ordinary skill in the art would further appreciate that any of the implementations could be provided in any combination with the other implementations disclosed herein. It is understood that the disclosure can be embodied in other specific forms without departing from the central characteristics thereof. The present examples and implementations, therefore, are to be considered in all respects as illustrative and not restrictive, and the disclosure is not to be limited to the details given herein. Accordingly, while the specific implementations have been illustrated and described, numerous modifications come to mind. The scope of the disclosure is therefore intended to be limited solely by the scope of the appended claims.

[00182] Any publications, including patents, patent applications and articles, referenced or mentioned in this specification are herein incorporated in their entirety into the specification, to the same extent as if each individual publication was specifically and individually indicated to be incorporated herein. In addition, citation or identification of any reference in the description of some implementations of the disclosure shall not be construed as an admission that such reference is available as prior art to the present disclosure.

Claims

<pat:ClaimStatement>CLAIMS< / pat:ClaimStatement> <pat:Claims com:id="claims"> <pat:Claim com:id="CLM-00001"> <pat:ClaimNumber>1< / pat:ClaimNumber> <pat:ClaimText>1. A pre-treatment screening assembly comprising: a spillbox feed tank defining a tank cavity and comprising a tailings inlet provided above an upper portion of the tank cavity for downwardly discharging a tailings fluid flow into the tank cavity; a screening device having a screening surface receiving the tailings fluid flow from the spillbox feed tank, the screening surface being configured to allow material smaller than a predetermined size that is included in the tailings fluid flow to flow through the screening surface and separate coarse debris larger than or equal to the predetermined size from the tailings fluid flow, thereby separating the tailings fluid into a coarse debris fraction and a screened tailings fluid; and a collector body arranged below the screening surface of the screening device to receive the screened tailings fluid. < / pat:ClaimText> < / pat:Claim> <pat:Claim com:id="CLM-00002"> <pat:ClaimNumber>2< / pat:ClaimNumber> <pat:ClaimText>2. The pre-treatment screening assembly according to claim 1, wherein the screening device comprises a cleaning device to remove the coarse debris from the screening surface. < / pat:ClaimText> < / pat:Claim> <pat:Claim com:id="CLM-00003"> <pat:ClaimNumber>3< / pat:ClaimNumber> <pat:ClaimText>3. The pre-treatment screening assembly according to claim 1 or 2, wherein the collector body comprises side walls at least partially delimiting a collecting cavity and further comprises a sand discharge opening formed in a bottom portion of the collector body for periodically removing sand accumulated in the collecting cavity. < / pat:ClaimText> < / pat:Claim> <pat:Claim com:id="CLM-00004"> <pat:ClaimNumber>4< / pat:ClaimNumber> <pat:ClaimText>4. The pre-treatment screening assembly according to claim 1 or 2, wherein the screening device has an upstream inlet, the tailings fluid being discharged on the screening surface at the upstream inlet, the collector body having side walls defining at least partially a collecting cavity of the collector body and a tailings discharge outlet for discharging the screened tailings fluid from the collecting cavity, the tailings discharge outlet being located vertically below the upstream inlet of the screening device. < / pat:ClaimText> < / pat:Claim> <pat:Claim com:id="CLM-00005"> <pat:ClaimNumber>5< / pat:ClaimNumber> <pat:ClaimText>5. The pre-treatment screening assembly according to any one of claims 1 to 4, further comprising an inlet line fluidly connected to the tailings inlet of the spillbox feed tank, the inlet line comprising an inlet distribution pipe extending substantially horizontally above the upper portion of the tank cavity. < / pat:ClaimText> < / pat:Claim> <pat:Claim com:id="CLM-00006"> <pat:ClaimNumber>6< / pat:ClaimNumber> <pat:ClaimText>6. The pre-treatment screening assembly according to claim 5, further comprising multiple spillbox feed tanks, wherein the inlet distribution pipe extends above a corresponding upper portion of the tank cavity of each of the multiple spillbox feed tanks. < / pat:ClaimText> < / pat:Claim> <pat:Claim com:id="CLM-00007"> <pat:ClaimNumber>7< / pat:ClaimNumber> <pat:ClaimText>7. The pre-treatment screening assembly according to claim 6, wherein the inlet distribution pipe comprises two opposed longitudinal outlets for the tailings fluid to be discharged downwardly into a respective one of the multiple spillbox feed tanks. < / pat:ClaimText> < / pat:Claim> <pat:Claim com:id="CLM-00008"> <pat:ClaimNumber>8< / pat:ClaimNumber> <pat:ClaimText>8. The pre-treatment screening assembly according to any one of claims 5 to 7, wherein the pre-treatment screening assembly further comprises an overflow weir extending outwardly from the upper portion of the tank cavity, the screening surface receiving the tailings fluid flow spilling over the overflow weir. < / pat:ClaimText> < / pat:Claim> <pat:Claim com:id="CLM-00009"> <pat:ClaimNumber>9< / pat:ClaimNumber> <pat:ClaimText>9. The pre-treatment screening assembly according to claim 8, wherein a width of the overflow weir is smaller than a width of the screening surface. < / pat:ClaimText> < / pat:Claim> <pat:Claim com:id="CLM-00010"> <pat:ClaimNumber>10< / pat:ClaimNumber> <pat:ClaimText>10. The pre-treatment screening assembly according to claim 8 or 9, wherein the spillbox feed tank comprises a baffle plate extending in the tank cavity to direct the tailings fluid flow towards the overflow weir. < / pat:ClaimText> < / pat:Claim> <pat:Claim com:id="CLM-00011"> <pat:ClaimNumber>11< / pat:ClaimNumber> <pat:ClaimText>11. The pre-treatment screening assembly according to claim 10, wherein the spillbox feed tank comprises a bottom wall and side walls extending upwardly from the bottom wall and the baffle plate extends in the tank cavity from one of the side walls and the bottom wall and comprises a portion parallel to one of the side walls. < / pat:ClaimText> < / pat:Claim> <pat:Claim com:id="CLM-00012"> <pat:ClaimNumber>12< / pat:ClaimNumber> <pat:ClaimText>12. The pre-treatment screening assembly according to claim 11, wherein the spillbox feed tank comprises two baffle plates arranged in the tank cavity in parallel relationship with two opposed side walls. < / pat:ClaimText> < / pat:Claim> <pat:Claim com:id="CLM-00013"> <pat:ClaimNumber>13< / pat:ClaimNumber> <pat:ClaimText>13. The pre-treatment screening assembly according to any one of claims 5 to 12, further comprising an adjustable inlet valve configured to adjust the tailings fluid inlet flow into the spillbox feed tank. < / pat:ClaimText> < / pat:Claim> <pat:Claim com:id="CLM-00014"> <pat:ClaimNumber>14< / pat:ClaimNumber> <pat:ClaimText>14. The pre-treatment screening assembly according to claim 13, wherein the adjustable inlet valve is arranged on the inlet line, the pre-treatment screening assembly further comprising an inlet transfer pump configured to feed the spillbox feed tank with the tailings fluid flow of the inlet line, the adjustable inlet valve cooperating with the inlet transfer pump. < / pat:ClaimText> < / pat:Claim> <pat:Claim com:id="CLM-00015"> <pat:ClaimNumber>15< / pat:ClaimNumber> <pat:ClaimText>15. The pre-treatment screening assembly according to claim 13 or 14, further comprising a discharge line receiving the screened tailings fluid from the collector body, wherein the pre-treatment screening assembly further comprises an adjustable outlet valve arranged on the discharge line. < / pat:ClaimText> < / pat:Claim> <pat:Claim com:id="CLM-00016"> <pat:ClaimNumber>16< / pat:ClaimNumber> <pat:ClaimText>16. The pre-treatment screening assembly according to claim 15, further comprising a discharge pump configured to make the screened tailings fluid flow through the discharge line, the adjustable outlet valve cooperating with the discharge pump. < / pat:ClaimText> < / pat:Claim> <pat:Claim com:id="CLM-00017"> <pat:ClaimNumber>17< / pat:ClaimNumber> <pat:ClaimText>17. The pre-treatment screening assembly according to any one of claims 5 to 12, wherein the pre-treatment screening assembly further comprises one or more level sensors for measuring a tailings fluid level in the tank cavity and / or within the collector body. < / pat:ClaimText> < / pat:Claim> <pat:Claim com:id="CLM-00018"> <pat:ClaimNumber>18< / pat:ClaimNumber> <pat:ClaimText>18. The pre-treatment screening assembly according to claim 17, wherein the one or more level sensors comprise at least two pressure transmitters arranged in the tank cavity to measure the pressure of the tailings fluid at at least two distinct locations of the tank cavity to determine the tailings fluid level therefrom. < / pat:ClaimText> < / pat:Claim> <pat:Claim com:id="CLM-00019"> <pat:ClaimNumber>19< / pat:ClaimNumber> <pat:ClaimText>19. The pre-treatment screening assembly according to claim 17 or 18, wherein the pre-treatment screening assembly further comprises an adjustable inlet valve configured to adjust the tailings fluid inlet flow in response to the tailings fluid level measured by the one or more level sensors. < / pat:ClaimText> < / pat:Claim> <pat:Claim com:id="CLM-00020"> <pat:ClaimNumber>20< / pat:ClaimNumber> <pat:ClaimText>20. The pre-treatment screening assembly according to any one of claims 17 to 19, wherein the pre-treatment screening assembly further comprises an inlet transfer pump configured to feed the spillbox feed tank with the tailings fluid in response to the tailings fluid level measured by the one or more level sensors. < / pat:ClaimText> < / pat:Claim> <pat:Claim com:id="CLM-00021"> <pat:ClaimNumber>21< / pat:ClaimNumber> <pat:ClaimText>21. A process for screening coarse debris from a tailings fluid flow provided by an inlet line, the process comprising: providing the tailings fluid flow to a pre-treatment screening assembly comprising a spillbox feed tank, a screening device and a collector body, the spillbox feed tank defining a tank cavity; filling the tank cavity of the spillbox feed tank with the tailings fluid flow of the inlet line through a tailings inlet provided above an upper portion of the tank cavity for discharging downwardly the tailings fluid flow into the tank cavity; discharging a tailings fluid outlet flow from the tank cavity onto the screening device, the screening device having a screening surface configured to allow material smaller than a predetermined size that is included in the tailings fluid flow to flow through the screening surface and separate coarse debris larger than or equal to the predetermined size from the tailings fluid flow, thereby separating the tailings fluid into a coarse debris fraction and a screened tailings fluid; and collecting the screened tailings fluid into the collector body. < / pat:ClaimText> < / pat:Claim> <pat:Claim com:id="CLM-00022"> <pat:ClaimNumber>22< / pat:ClaimNumber> <pat:ClaimText>22. The process according to claim 21, further comprising modifying at least one of an inlet flow rate and an outlet flow rate of the spillbox feed tank. < / pat:ClaimText> < / pat:Claim> <pat:Claim com:id="CLM-00023"> <pat:ClaimNumber>23< / pat:ClaimNumber> <pat:ClaimText>23. The process according to claim 22, further comprising measuring a level of tailings fluid in the tank cavity and modifying the at least one of an inlet flow rate and an outlet flow rate of the spillbox feed tank in response to the tailings fluid level measured in the tank cavity. < / pat:ClaimText> < / pat:Claim> <pat:Claim com:id="CLM-00024"> <pat:ClaimNumber>24< / pat:ClaimNumber> <pat:ClaimText>24. The process according to any one of claims 21 to 23, further comprising removing at least one of sand accumulated in the collector body and coarse debris from the screening surface. < / pat:ClaimText> < / pat:Claim> <pat:Claim com:id="CLM-00025"> <pat:ClaimNumber>25< / pat:ClaimNumber> <pat:ClaimText>25. The process according to any one of claims 21 to 24, further comprising applying vibrations to the screening surface. < / pat:ClaimText> < / pat:Claim> < / pat:Claims>