CA3077551A1 - Enhanced dewatering of mining tailings employing aluminosilicate pre-treatment - Google Patents

Abstract

The invention relates to a process for separating solids from an aqueous slurry con-taining particulate material, which particulate material comprises sand particles and fines particles and contains clay particles, which aqueous suspension has a solids content of from 30 to 70% by weight and a sand to fines ratio of from greater than 1:1 to 3:1, which process comprises applying a treatment system to the aqueous slurry to cause flocculation of the particulate material, and subsequently separating the so formed flocculated particulate material as solids from the slurry, in which the treatment system comprises (a) at least one aluminosilicate nanoparticulate material, in which the molar ratio of aluminium to silicon is from 0.7:1 to 3:1; (b) at least one polymeric flocculant, which has an intrinsic viscosity of at least 5 dl/g (measured at 25 C in 1 M NaCI), and (c) optionally, at least one cationic coagulant. In addition, the present invention also encompasses a composition formed from an aqueous slurry containing particulate material, which particulate material comprises sand particles and fines particles and contains clay particles, which aqueous suspen-sion has a solids content of from 30 to 70% by weight and a sand to fines ratio of from greater than 1:1 to 3:1, which composition comprises flocculated particulate sol-ids and a treatment system in which the treatment system comprises: (a) at least one aluminosilicate nanoparticulate material, in which the molar ratio of aluminium to sili-con is from 0.7:1 to 3:1; (b) at least one polymeric flocculant, which has an intrinsic viscosity of at least 5 dl/g (measured at 25 C in 1 M NaCI), and (c) optionally, at least one cationic coagulant. Further, the invention relates to the aforementioned treatment system and its use. The invention provides effective dewatering of aqueous slurries containing particulate material having sand and fines components and containing clay particles employing a new treatment system to yield a dewatered particulate material.

Description

Enhanced Dewatering of Mining Tailings Employing Aluminosilicate Pre-treatment Background of the Invention Field of the Invention The present invention, in one of its aspects, relates to a process for treating an aqueous slurry such as a tailings stream from a mineral processing operation.
Said process employs a treatment system that includes at least one aluminosilicate nano-particulate material and at least one polymeric flocculent. In another of its aspects, the present invention also relates to an aqueous composition containing an aqueous slurry of particulate material comprising sand particles and fines particles and also contains at least one aluminosilicate nanoparticulate material and at least one poly-meric flocculent.
Description of the Prior Art Processes of treating mineral ores, coal or oil sands to extract mineral values or in the case of coal and oil sands to recover the hydrocarbons, will normally result in waste material from the beneficiation process. Often the waste material is an aque-ous slurry or sludge comprising particulate mineral material, for instance clay, shale, sand, grit, oil sands tailings, metal oxides etc. admixed with water.
Typically, the slurry of waste material would be thickened in one or more gravity sed-imentation vessels, which are sometimes referred to as thickeners, to concentrate the solids and recover some of the water content. In some processes where the val-uable metal is recovered by dissolution or leaching, the waste solid material may be separated from the liquor containing the mineral values by a series of counter current sedimentation vessels, sometimes referred to as a recovery circuit. In the Bayer alu-mina process for example, following an initial digestion stage, the solids, often re-ferred to as red mud, would be passed to an initial gravity sedimentation vessel, often referred to as a thickener, and washed in the liquor from subsequent gravity sedi-mentation vessels, often referred to as washer vessels. The solids from the initial thickener stage would be passed from the base of the vessel as an underflow and Date recue/Received Date 2020-04-06

2 into the first of a series of counter current sedimentation vessels (washer vessels), in which the solids from each washer vessel would be passed as an underflow succes-sively to each subsequent washer vessel and in which an aqueous liquor is used to wash the solids in each stage before being passed to each previous washer stage and then finally into the first thickener stage. Polymeric flocculants may be added into any one or more thickener or water stages to assist with the solids liquid separation.
The waste solids from the last washer stage would then be passed as an underflow to a disposal area, for example a lake or tailings dam.
GB 2080272 describes aqueous suspensions of red mud being removed from the Bayer process for making alumina by the addition of at least the first stage of the re-covery circuit of a flocculants selected from starch, homopolymers of acrylic acid or acrylates, copolymers of acrylic acid or acrylates containing at least 80 molar percent acrylic acid or acrylate monomers and combinations thereof and subsequent addition to later, more dilute stages in the recovery circuit of a copolymer containing from about 35 to 75 molar percent of acrylic acid or acrylate and from about 65 to 25 molar percent of acrylamide monomers.
US 5653946 refers to a process for fluidifying flocculated aqueous suspensions of red muds in the production of alumina from bauxite by the Bayer process, which con-sists: in dissolving bauxite using sodium hydroxide; then, in decanting and in washing the red muds formed in order to separate them from the alumina in successive vats, while recycling the washing water upstream; and finally, in eliminating the red muds thus treated; and in which a flocculant consisting of a polyacrylamide of molecular weight greater than 10 million is introduced into the suspension of one of the succes-sive vats; wherein a dispersing agent formed by an anionic acrylic acid polymer of molecular weight lower than 50,000 is added simultaneously with said flocculant to the suspension in the same vat.
Addition of chemical additives to enhance recovery of components in other areas such as extraction of bitumen from oil sands or water treatment or papermaking is also known.
Date recue/Received Date 2020-04-06

3 WO 2010 088388 describes a method of treating an aqueous slurry to disperse and separate components of the slurry, to enhance recovery of the components of the slurry and to enhance dewatering of the solids in the resulting residual slurry for wa-ter recovery and solids reclamation. The method involves providing an aqueous slur-ry by slurrying a solid mineral component; adding to this slurry a sodium or potassium zeolite having a weight ratio of aluminium to silicon in the range of about 0.72:1 to about 1.3:1 in an amount sufficient to disperse and separate components of the slur-ry to form a dispersed slurry. The method involves adding to this dispersed slurry suf-ficient quantities of a source of multivalent cations to react with the zeolite to immedi-ately neutralise the dispersive effect of the zeolite causing the solid components to immediately begin to aggregate and settle. This is said to enhance separation and subsequent recovery of solid components of the slurry and enhance subsequent wa-ter removal and consolidation of residual components of the slurry.
WO 98/52877 describes a method of treating water to coagulate particulate matter contained therein. The method involves sequential steps of providing an aqueous suspension comprising particulate matter with multivalent cations absorbed on the surface of the particulate matter; optionally adding a source of multivalent cations;
optionally adding a cationic polyacrylamide, adding a sodium or potassium zeolite crystalloid coagulant (ZOO) having particulate sizes of at least about 4 nm and hav-ing a weight ratio of aluminium to silicon in the range of about 0.72:1 to about 1.3:1 in which the suspension has sufficient respective of amounts of the multivalent cations and the ZCC to effect coagulation of the particulate matter by ion exchange between the absorbed cations and the sodium or potassium present in the ZOO.
In a typical mineral, coal or oil sands processing operation, waste solids are separat-ed from solids that contain mineral valuables or hydrocarbon in an aqueous process.
The aqueous suspensions of waste solids often contain clays and other minerals and are usually referred to as tailings. These solids are often concentrated by a floccula-tion process in a gravity thickener to give a higher density underflow and to recover some of the process water.
In some cases, the waste material such as mine tailings can be conveniently dis-posed of in an underground mine as backfill. Generally, this waste comprises a high Date recue/Received Date 2020-04-06

4 proportion of coarse large sized particles together with other smaller sized particles and is pumped into the mine as a slurry, occasionally with the addition of a pozzolan, where it is allowed to dewater leaving a sedimented solid in place. It is commonplace to use flocculant to assist this process by flocculating the fine material to increase the rate of sedimentation. However, in this instance, the coarse material will normally sediment at a faster rate than the flocculated fines, resulting in a heterogeneous de-posit of coarse and fine solids.
For other applications it may not be possible to dispose of the waste in an under-ground mine. In these cases, it is common practice to dispose of the material, by pumping the aqueous slurry or underflow to lagoons, heaps or stacks, which may be above ground, or into open mine voids, or even purpose-built dams or containment areas. It is usual to pump the aqueous slurry to a surface holding area, often referred to as a tailings pit or dam or more usually a tailings pond in the case of oil sands.
This initial placement of the mining waste into the disposal area may be as a free-flowing liquid, thickened paste or the material may be further treated to remove much of the water, allowing it to be stacked and handled as a solid-like material.
Once de-posited at this surface holding area, water will continue to be released from the aqueous suspension resulting in further concentration of the solids over a period of time through the actions of sedimentation, drainage and evaporation. Once a suffi-cient volume of water has been collected this is usually pumped back to the mineral or oil sands processing plant.
For example, in the case where the tailings are sent to the disposal area in a liquid and fluid form, they must be contained in a lagoon by dams or similar impoundment structures. The tailings may have been pretreated by adding flocculating agents and thickened in a gravity thickener to remove and recover some of the water content, but the overall solids content is such that the fluid has no, or a low yield stress, and hence the material behaves largely as a liquid on deposition. These lagoons may be relatively shallow, or relatively deep, depending upon how much land is available, the location for building impoundment area and other geotechnical factors generally with-in the vicinity of the mine site. Dependent upon the nature of the solid particles in the waste, often the particles will gradually settle from the aqueous slurry and form a compact bed at the bottom of the deposition area. Released water may be recovered Date recue/Received Date 2020-04-06 by pumping or is lost to the atmosphere through evaporation and groundwater through drainage. It is desirable to remove the aqueous phase from the tailings whereby the geotechnical moisture content is below the liquid limit of tailings solids, in order to manage the remaining tailings in a form that has a predominantly solid or

5 semi-solid handling characteristic. Numerous methods can be employed to achieve this, the most common, when the material properties of the tailings allow, is self-weight consolidation in a tailings dam, whereby the permeability of tailings is suffi-cient enough to overcome the filling rate of the dam and water can be freely released from the tailings. Where the permeability of the tailings is not sufficient for water to escape freely, polymers are typically used to improve permeability thereby making the tailings more suitable for a self-weight consolidation process.
Eventually, it may be possible to rehabilitate the land containing the dewatered solids when they are sufficiently dry and compact. However, in other cases, the nature of the waste solids will be such that the particles are too fine to settle completely into a compact bed, and although the slurry will thicken and become more concentrated over time, it will reach a stable equilibrium whereby the material is viscous but still fluid, making the land very difficult to rehabilitate. It is known that the flocculants are sometimes used to treat the tailings before depositing them into the disposal area, to increase the sed-imentation rate and increase the release of water for recovery or evaporation.
In an alternative method, the tailings may be additionally thickened, often by the treatment with polymeric agents, such that the yield stress of the material increases so that the slurry forms heaps or stacks when it is pumped into the deposition area.
Specialised thickening devices such as Paste Thickeners or Deep Cone Thickeners may be used to produce an underflow with the required properties.
Alternatively, the polymeric agents may be added the tailings slurry during the transfer or discharge into the disposal area, to render the material less mobile and achieve the required yield stress. This heaped geometry aids more rapid dewatering and drying of the ma-terial to a solid-like consistency as the water is removed and recovered more rapidly through run-off and drainage, and the compaction of the solids may occur more rap-idly through the increased weight and pressure of the solids when formed into a heap or a stack. In some instances, the deposition of the solids is controlled to build up relatively narrow bands of tailings which can also dewater quickly through evapora-tion, prior to adding a new layer of treated waste material on top. This is sometimes Date recue/Received Date 2020-04-06

6 referred to as thin lift or dry stacking. Typically, each relatively narrow band of tailings (i.e. each layer of treated waste material) would tend to have a thickness of from 0.1 to 0.5 m. In the case of red mud, this material often has sufficient yield stress to form the layered stacks without further polymer treatment and this method has been wide-ly used to dispose of tailings from alumina processing for a number of years.
Air dry-ing of tailings can be used to great effect where the environment has some evapora-tion potential and there is enough land area to spread the tailings thinly enough for this process to be effective. Where the area for evaporation is limited it is possible for the polymers to be added to the tailings to improve this process. The addition of the polymer may increase the permeability of the tailings whereby at least about 20% by weight of water can be allowed to drain, while another 20% of the water that is typi-cally more associated with the particle surfaces and the clay matrix can be removed through evaporation.
It is often useful for the tailings pond or dam to be of limited size to minimise the im-pact on the environment. In addition, providing larger tailings ponds can be expen-sive due to the high costs of earthmoving and the building of containment walls.
These ponds tend to have a gently sloping bottom which allows any water released from the solids to collect in one area and which can be pumped back to the plant. A
problem that frequently occurs is when the size of the tailings pond and the dam are not large enough to cope with the output of tailings from the mineral processing op-eration. Another problem that frequently occurs is when fine particles of solids are carried away with the run-off water. Thus, the released water containing the fine par-ticles could have a detrimental impact on recycling and subsequent uses of the wa-ter.
Another method for disposal of the mine tailings is to use mechanical dewatering de-vices such as filters and centrifuges. Such mechanical dewatering devices are able to remove a significant amount of water from the aqueous mineral slurry, such that the waste material may be deposited in the disposal area directly with a solid like consistency. In many cases, it is necessary to treat the tailings with polymeric floccu-lating agent immediately prior to the mechanical dewatering step, to enable this equipment to perform efficiently and achieve the degree of dewatering required.
Date recue/Received Date 2020-04-06

7 A further method for disposal of the mine waste is through filtration in a Geotube0, whereby the aqueous slurry placed into a permeable geotextile bag which retains the solids particles and some of the water is released by a filtration process, escaping through the walls of the geotextile bag. In some cases, where the starting permeabil-.. ity of the mine tailings is low, it may be desirable to add a flocculating agent in order to increase the filtration rate and improve the retention of fine solids within the Geo-tube .
For example, in oil sands mining, the ore is processed to recover the hydrocarbon fraction, and the remaining material, constitutes the tailings. In the oil sands extrac-tion process, the main process material is water, and the tailings are mostly sand with some silt and clay, with some residual bitumen. Physically, the tailings consist of an easily dewatered, solid part (sand tailings) and a more fluid part (sludge). The most satisfactory place to dispose of the tailings, is of course in the existing excavat-ed hole in the ground. Nevertheless, the sand tailings alone from the one cubic foot of ore occupy just about one cubic foot. The amount of sludge is variable, depending on the quality and process conditions, but average about 0.3 ft3. The tailings simply will not fit into the hole in the ground. Therefore, there is generally a requirement to build additional impoundment areas for the tailings.
Within the oil sands industry, there are many different types of process tailings streams as defined in Technical Guide for Fluid Fine Tailings Management, COSIA
2012, which may require treatment with polymeric agents. One example is "fine fluid tailings" (FFT) which is the fines fraction (mainly silt and clay) from the process after the hydrocarbon content has been largely recovered, and the sand fraction has been largely removed, usually by passing the "whole tailings" (WT) through a cyclone. The solids content of the fine fluid tailings may vary significantly, depending upon if mate-rial has been thickened by gravity sedimentation. Whole Tailings (WT) may be re-garded as tailings produced from primary or secondary separation vessels of the ex-traction plant and contains sand, fines and water. In general, the sand to fines ratio of the WT are greater than 4:1 and may be as high as 20:1.
Another example is "composite tails" (CT) in which all the particle size ranges are present (sand, silt and clay). This may be the whole tailings, prior to the removal of Date recue/Received Date 2020-04-06

8 the sand, or other tailings streams which may be formed by subsequent mixing of fine tailings with sand fractions, to varying degrees. The sand to fines ratio of CT
tend to be greater than 3:1 and may be as high as 6:1 or 7:1. A further example is "mature fines tailings" (MFT) which are formed after storage of fluid fine tailings, or in some cases combine tailings, in a tailings pond for several years. FFT tend to have sand to fines ratios significantly below 1:1 and MFT tend have much lower sand con-tents typically less than 0.3:1, for instance less than 0.25:1.
In the oil sands fine tailings pond, the process water, any residual hydrocarbons and minerals settle naturally to form different strata. The upper stratum can be predomi-nantly water that may be recycled as process water to the extraction process.
The lower strata can contain settled residual hydrocarbon and minerals which are pre-dominantly fines, usually clay. It is usual to refer to this lower stratum as mature fines tailings. It is known that mature fines tailings consolidate extremely slowly and may take many hundreds of years to settle into a consolidated solid mass.
Consequently, mature fines tailings and the ponds containing them are a major challenge to tailings management and the mining industry.
The composition of mature fines tailings tends to be variable. The upper part of the stratum may have a mineral content of about 10% by weight but at the bottom of the stratum the mineral content may be as high as 50% by weight. The variation in the solids content is believed to be because of the slow settling of the solids and consol-idation occurring over time. The average mineral content of the MFT tends to be of about 30% by weight. MFT behaviour is typically dominated by clay behaviour, with the solids portion of the MFT behaving more as a plastic-type material than that of a coarser, more friable sand.
The MFT frequently comprises a mixture of sand, fines and clay. Generally, the sand is defined as siliceous particles of any size greater than 44 pm and may be a com-ponent of the MFT solids in an amount of up to 50% by weight. The remainder of the mineral content of the MFT tends to be made up of a mixture of clay and fines (silts).
Generally, fines refer to mineral particles no greater than 44 pm. The clay may be any material traditionally referred to as clays by virtue of its mineralogy and will gen-erally have a particle size of below 2 pm. Typically, the clays tend to be a blend of Date recue/Received Date 2020-04-06

9 kaolin, illite, chlorite and water swelling clays, such as smectites which are some-times referred to as montmorillonites and may be interlayered with the other types of clay. Additional variations in the composition of MFT may be as a result of the resid-ual hydrocarbon which may be dispersed in the mineral tailings and may segregate in the tailings pond into mat layers of hydrocarbon. The MFT in a pond not only has a wide variation of compositions distributed from top to bottom of the pond but there may also be pockets of different compositions at random locations throughout the pond.
It has been known to treat aqueous slurry such as tailings using polymer flocculants.
See, for example, any of:
EP-A-388108;
WO 96/05146;
WO 01/92167;
W004/060819;
WO 01/05712; and W097/06111.
Canadian patent 2,803,904 teaches the use of high molecular weight multi valent anionic polymers for clay aggregation. Specifically, a polymer comprising an anionic water-soluble multivalent cation-containing acrylate copolymer is described.
Canadian patent 2,803,025 teaches a polymer similar to the polymer taught in Ca-nadian patent 2,803,904 with the proviso that the polymer has an intrinsic viscosity of less than 5 dl/gm.
US 8721896 B1 describes a method of treating an aqueous mineral slurry to dis-perse and separate components of the slurry, to enhance the recovery of compo-nents of the slurry, and to enhance dewatering of the solids in the resulting residual slurry. The method involves providing an aqueous slurry comprising slurrying water and solid mineral components, optionally adding to the aqueous slurry a sodium or potassium zeolite having a weight ratio of aluminium to silicon in the range of about 0.72:1 to about 1.3:1 in an amount sufficient to disperse and separate the compo-nents of the slurry; adding to the dispersed slurry initially provided all the dispersed slurry having been treated with the zeolite a water solution of a polymer reactive with the mineral components in which the polymer is said to be selected from water-Date recue/Received Date 2020-04-06 soluble multivalent cation containing acrylate copolymers having an IV of less than 5 dl/g.
US 2017/0349461 claims a method for separating mature fine tailings from suspen-5 sion comprising mature fine tailings and water which involves introducing inorganic nanoparticles into the suspension such that the inorganic nanoparticles interact with the mature fines tailings. The inorganic nanoparticles are said to have a diameter of 50 nm or smaller. Paragraph [0023] relating to the examples reveals that four types of nanoparticles were investigated: (i) alumina (<50 nm), (ii) cationic nano silica (10-

10 20 nm) (powder and colloid); (iii) anionic nanosilica (5 nm), and (iv) magnesium ox-ide (30 nm).
WO 2017/084986 describes a multivalent cation containing copolymer derived from one or more ethylenically unsaturated acids. The copolymer has the following char-acteristics: (a) an intrinsic viscosity of at least about 3 dl/g when measured in 1 M
NaCI solution at 25 C, (b) the copolymer is derived from a monomer mixture com-prising an ethylenically unsaturated acid and at least one comonomer, the ethyleni-cally unsaturated acid present in an amount in the range of from about 5% to about 65% by weight; and (c) a residual comonomer content of less than 1000 ppm when the comonomer is an acrylamide. The copolymer, inter-alia, is useful as a flocculent for treating an aqueous slurry comprising particulate material, preferably tailings from a mining operation.
Canadian 2,831,352 discloses a process for dewatering fluid fine tailings, comprising combining fluid fine tailings with fresh oil sands tailings to create a tailings mixture having a sand to fines ratio of about 1.0 to about 2Ø Optionally, the tailings mixture may be diluted with water to an optimal density. An aqueous polymeric flocculent is then added to the tailings mixture with mixing of the polymeric flocculants and tail-ings mixture to form a flocculated material. This is then transferred to a deposition cell for dewatering.
US 2018/0201528 describes a method of dewatering an aqueous mineral suspension comprising introducing into the suspension flocculating system comprising a mixture of polyethylene glycol and polyethylene oxide polymers. The mixture of polyethylene Date recue/Received Date 2020-04-06

11 glycol and polyethylene oxide polymers is said to be useful for the treatment of sus-pensions of particulate material, especially waste mineral slurries and is said to be particularly suitable for the treatment of tailings and other waste material resulting from mineral processing, in particular, the processing of oil sands tailings.
Clay-based minerals are known to cause problems in mineral processing operations.
When the mined ore contains significant amounts of clay, then treatment and dispos-al of the waste (gangue) material after the recovery (beneficiation) of the valuables is often problematic. This is because the stacked platelets of a clay mineral particle tend to delaminate (or break apart) when contacted with water and these delaminat-ed platelets form (or rearrange into) network type structures held together by electro-static forces between the edges and the faces of the clay platelets. The high specif-ic surface area, combined with the hydrophilic nature of the surfaces, causes water to become trapped with solids, and the waste is then difficult to concentrate and dewat-er. This can result in both excessive volumes of waste material, soft deposits which do not compact readily over time, and loss of process water.
Polymeric flocculants, such as Magnafloc0 and Rheomax0 ETD ranges, supplied by BASF, have been used to enhance the rate of settling and dewatering of tailings de-posits. However, in some cases, whilst the polymers do improve the rate and extent of water removal to some degree, this is not sufficient to increase the solids content of the material beyond the plastic limit of the system and, further self-weight compac-tion does not occur, leading to the creation of soft deposits which are not suitable for rehabilitation.
One such example is the Canadian oil sands industry, where it is well documented that their fine tailings will remain semi-fluid for many hundreds of years, except where the process allows for a significant amount of water evaporation and atmospheric drying. This problem is especially the case for deep pour deposits of tailings, which make the most effective use of land and mining voids but have limited opportunity for evaporative dewatering. Evaporation to dewater tailings to a solids content above the plastic point can only be used on relatively thin layers of deposited tailings, which requires a massive area of land to operate effectively.
Date recue/Received Date 2020-04-06

12 Another industry which also produces problematic high clay containing tailings is the phosphate industry, for example in Florida, USA.
There is a need for a more effective process for dewatering waste solids containing clays, especially one that improves upon or overcomes the aforementioned prob-lems.
Summary of the Invention The present invention provides a process for separating solids from an aqueous slur-ry containing particulate material, which particulate material comprises sand particles and fines particles and contains clay particles, which aqueous suspension has a sol-ids content of from 30 to 70% by weight and a sand to fines ratio of from greater than 1:1 to 3:1, which process comprises applying a treatment system to the aqueous slurry to cause flocculation of the particulate material, and subsequently separating the so formed flocculated particulate material as solids from the slurry, in which the treatment system comprises (a) at least one aluminosilicate nanoparticulate material, in which the molar ratio of aluminium to silicon is from 0.7:1 to 3:1;
(b) at least one polymeric flocculent, which has an intrinsic viscosity of at least 5 dl/g (measured at 25 C in 1 M NaCI), and (c) optionally, at least one cationic coagulant.
By applying a treatment system to the aqueous slurry, the process of the present in-vention includes applying the treatment system, including the components thereof, to any one or more components used to form the aqueous slurry. Further, the treatment system may be applied to the aqueous slurry by addition of at least one of the treat-ment system components to a component forming the aqueous slurry and at least one of the treatment system components to another component forming the aqueous slurry. In addition, the treatment system may be applied to the aqueous slurry by ad-dition of at least one of the treatment system components to at least one component forming the aqueous slurry and the remainder of the treatment system components may be added to the aqueous slurry to be treated according to the present invention.
Thus, where, for instance, the aqueous slurry is formed by combining any one or Date recue/Received Date 2020-04-06

13 more of whole tailings (WT), composite tailings (CT), mature fines tailings (MFT), fluid fines tailings (FFT), thin fines tailings (TFT) and/or thickened fines tailings (ThFT) together with other components of the aqueous slurry such as sand, the treatment system may be applied to any one or more of these components forming the aqua-ous slurry or may be split across different components streams or a combination of different components streams and the final aqueous slurry at different components of the treatment system may be added to different components streams of the aqueous slurry.
The invention also relates to a composition formed from an aqueous slurry containing particulate material, which particulate material comprises sand particles and fines particles and contains clay particles, which aqueous slurry has a solids content of from 30 to 70% by weight and a sand to fines ratio greater than 1:1 to 3:1, which composition comprises flocculated particulate solids and a treatment system in which the treatment system comprises (a) at least one aluminosilicate nanoparticulate material, in which the molar ratio of aluminium to silicon is from 0.7:1 to 3:1;
(b) at least one polymeric flocculant, which has an intrinsic viscosity of at least 5 dl/g (measured at 25 C in 1 M NaCI), and (c) optionally, at least one cationic coagulant.
The invention further relates to a treatment system for separating solids from an aqueous slurry containing particulate material, which particulate material comprises sand particles and fines particles and contains clay particles, which aqueous slurry has a solids content of from 30 to 70% by weight and a sand to fines ratio of greater than 1:1 to 3:1, in which the treatment system comprises (a) at least one aluminosilicate nanoparticulate material, in which the molar ratio of aluminium to silicon is from 0.7:1 to 3:1;
(b) at least one polymeric flocculant, which has an intrinsic viscosity of at least 5 dl/g (measured at 25 C in 1 M NaCI), and (c) optionally, at least one cationic coagulant.
Date recue/Received Date 2020-04-06

14 The invention additionally relates to the use of said treatment system for separating solids from an aqueous slurry.
Description of Drawings Figure 1 illustrates filtration apparatus employed in the test work of the examples.
Figure 2 is a graphical representation of the results of the filter cake moisture content variance on the dose of aluminosilicate nanoparticulate material Product A and em-ploying 700 g/t of Flocculent A from Table 1 of Example 5.
Figure 3 is a graphical representation of the results of turbidity variance on the dose of aluminosilicate nanoparticulate material Product A and employing 700 g/t of Floc-culent A from Table 1 of Example 5.
Figure 4 is a graphical representation of the results of the filter cake moisture content variance on the dose of aluminosilicate nanoparticulate material Product A and em-ploying 700 g/t of Flocculent B from Table 2 of Example 5.
Figure 5 is a graphical representation of the results of turbidity variance on the dose of aluminosilicate nanoparticulate material Product A and employing 700 g/t of Floc-culent B from Table 2 of Example 5.
Figure 6 is a graphical representation of the results of the filter cake moisture content variance on the dose of aluminosilicate nanoparticulate material Product A and em-ploying 700 g/t of Flocculent A from Table 3 of Example 6.
Figure 7 is a graphical representation of the results of turbidity variance on the dose of aluminosilicate nanoparticulate material Product A and employing 700 g/t of Floc-culent A from Table 3 of Example 6.
Figure 8 is a graphical representation of the results of the filter cake moisture content variance on the dose of aluminosilicate nanoparticulate material Product A and em-ploying 900 g/t of Flocculent A from Table 4 of Example 7.
Figure 9 is a graphical representation of the results of turbidity variance on the dose of aluminosilicate nanoparticulate material Product A and employing 900 g/t of Floc-culant A from Table 4 of Example 7.
Figure 10 is a graphical representation of the results of the filter cake moisture con-tent variance on the dose of aluminosilicate nanoparticulate material Product A and employing lkg/t of Flocculent B from Table 5 of Example 7.
Date recue/Received Date 2020-04-06 Figure 11 is a graphical representation of the results of turbidity variance on the dose of aluminosilicate nanoparticulate material Product A and employing lkg/t of Floccu-lent B from Table 5 of Example 7.
Figure 12 is a graphical representation of the results of the filter cake moisture con-5 tent variance on the dose of aluminosilicate nanoparticulate material Product A, Product B, Product C or Product D and employing 400 g/t of Flocculent B from Table 6 of Example 8.
Figure 13 is a graphical representation of the results of turbidity variance on the dose of aluminosilicate nanoparticulate material Product A, Product B, Product C or Prod-10 uct D and employing 400 g/t of Flocculent B from Table 6 of Example 8.
Figure 14 provides a graphical representation of the natural coagulation state of clays, showing a plot of suspension (aqueous slurry) viscosity (mPas) versus pH and providing two-dimensional representations of the respective coagulated structure of the clay platelets.
Detailed Description The aqueous slurry should have a solids content of from 30% to 70% by weight of the aqueous slurry. The aqueous slurry to be treated may already have a solids con-tent within this range. Typically, however, an aqueous slurry may have undergone some sort of initial thickening stage where an amount of the aqueous liquid may have been removed. Such an initial thickening stage may, for instance, be a sedimentation stage, such as in a thickening or sedimentation vessel or in a pit.
Alternatively, the thickening stage may include a belt thickener or a centrifuge. Other means of bring-ing the solids content to within the required range may also be possible.
By particulate mineral solids we mean that the solids include mineral or mining solids, typically from a mining or mineral processing operation. The particulate solids in the slurry may, for instance, contain filter cake solids or tailings. Often, the particulate mineral material comprises tailings. Suitably, the aqueous slurry may comprise phos-phate slimes, gold slimes or wastes from diamond processing. Typically, the particu-late mineral material is selected from the group consisting of coal fines tailings, min-eral sands tailings, red mud (alumina Bayer process tailings), oil sands tailings, ma-Date recue/Received Date 2020-04-06 ture fines tailings, zinc ore tailings, lead ore tailings, copper ore tailings, silver ore tailings, uranium ore tailings, nickel ore tailings and iron ore tailings.
Suitably the at least one aluminosilicate nanoparticulate material (a) should be added to the aqueous slurry before adding the at least one polymeric flocculent (b).
Typical-ly, the at least one aluminosilicate nanoparticulate material (a) may be added to the aqueous slurry first and subsequently the at least one polymeric flocculent (b) should be added. The optional component (c) of the treatment system, the at least one cati-onic coagulant, may be added to the aqueous slurry after the addition of the at least one aluminosilicate nanoparticulate material (a) but before the addition of the at least one polymeric flocculent (b) or alternatively the optional at least one cationic coagu-lant (c) may be added subsequently to the at least one polymeric flocculent (b). In some cases, it may even be desirable to add the optional at least one cationic coagu-lant (c) simultaneously with the addition of the at least one polymeric flocculent (b).
Suitably, the aqueous slurry employed in the present invention may comprise clay in a coagulated state and the treatment system comprises adding to the aqueous slurry aluminosilicate nanoparticulate material (a) to reduce the coagulated state of the clay particles to a less coagulated state within the aqueous slurry and then addition of the polymeric flocculent (b) to flocculate the sand and de-coagulate treated clay particles.
By clay being in a coagulated state, we mean that clay platelets are linked to each other, typically by electrostatic forces on the platelet faces and/or edges.
Clays may exist in a number of coagulated states and typically these include arrangements where the platelets are linked in a face-to-face structure; a mixture of face-to-face and edge to face structures; a mixture of edge to face and edge-to-edge structures;
and edge-to-edge structures. When the clay is in a substantially un-coagulated form the clay platelets tend to be substantially separated. Aqueous slurries tend to exhibit highest viscosity when the clay platelets contain edge to face structures, for instance mixtures of edge to face and edge-to-edge structures and especially mixtures of edge to face and edge-to-edge structures. This is illustrated in Figure 14.
Those aqueous slurries which contain clay in a coagulated form, particularly where the coagulated structure induces high viscosities, for instance as understood often to Date recue/Received Date 2020-04-06 be the case when the slurries are oil sands MFT slurries or oil sands FFT
slurries, tend to be particularly difficult to dewater.
The inventors realised that by employing a treatment system that includes an alumi-nosilicate nanoparticulate material as part of the treatment system in conjunction with a polymeric flocculent for clay containing aqueous slurries, more effective dewatering can be achieved. Without being limited to theory, it is believed that the effectiveness of the present process involving the special treatment system may be as a result of breaking down the electrostatic forces between coagulated clay platelets so as to .. allow the polymer chains of the flocculent to attach to a greater proportion of the sus-pended solids without interference from the coagulated clay. This allows for the im-proved release of water which would have been otherwise trapped inside of the co-agulated clay structures. The inventors believe that the aluminosilicate nanoparticu-late material may be acting on the coagulated clay particles by breaking down or di-minishing electrostatic attractive forces between them and hence transforming the clay particles into a coagulated form of fully and/or partially separated particles (as depicted in Figure 14).
In addition, the inventors have found that the employment of the treatment system facilitates the co-disposal of the fines and the sand. Desirably, this treatment enables the deposited solids separated from the aqueous slurry to contain both the fines and sand particles forming a relatively homogenous deposit with minimal segregation of fines and sand particles. Prevention of segregation during co-disposal of the fines and sand particles is important because otherwise the heavier sand particles would tend to settle faster while the fines would take longer to settle and would tend to be washed away with the liquid separated from the slurry. Thus, in the process accord-ing to the invention the liquid separated from the aqueous slurry tends to have a low-er fines particles content. This can be measured by well-known filtration techniques.
Suitably, the liquid separated from the aqueous slurry should have a solids content of less than 5% by weight of the total separated liquid. Preferably the solids content is less than 2% by weight of the total separated liquid, more preferably less than 1% by weight of the total separated liquid, even more preferably from 0.001% to 0.75% by total weight of the separated liquid, still more preferably from 0.01% to 0.5%
by total Date recue/Received Date 2020-04-06 weight of the separated liquid, often from 0.01% to 0.1% by total weight of separated liquid.
The particulate material contained in the aqueous slurry includes sand and fines. By sand we mean mineral solids (excluding gravel) with a particle size greater than 44 pm and generally less than 2 mm (not including bitumen). By fines we mean mineral solids, such as silts, with a particle size of equal to or less than 44 pm (not including bitumen). In general, the clay component of the aqueous slurry is part of the fines component. Thus, fines include the clay component as well as any other non-clayey mineral particles of the aforementioned size range. The particulate solid material con-tained in the aqueous slurry usually comprises a sand to fines ratio of greater than 1:1 to 3:1. By greater than 1.1 we mean just above 1.1, for instance 1.11 or 1.12.
Thus, the sand to fines ratio may be from 1.11:1 to 3:1 or from 1.12:1 to 3:1.
Other desirable ranges include from 1.15:1 to 3:1 or from 2:1 to 3:1 or from 1.15:1 to 2.9:1 or from 2:1 to 2.9:1 or from 2:1 to 2.8:1. The aqueous slurry may have a fines solids content of from 10% to 45%, by total weight of aqueous slurry.
The invention is of particular applicability where the aqueous slurry is derived from an oil sands fluid fines tailings (FFT), thickened fine tailings (ThFT) or a mature fines tailings (MFT). Fluid fine tailings (FFT) are generally understood to mean a liquid suspension of oil sands fine tailings or fines dominated tailings in water, with a solids content greater than 2% but less than the solids content corresponding to the Liquid Limit. Mature fines tailings are understood to be a more specific category of fluid fine tailings with a sand to fines ratio of less than 0.3 and a solids content typically greater than 30%. Thin fine tails (TFT) may be understood to be a category of fluid fine tail-ings with a sand to fines ratio of less than 0.3 and a solids content typically between

15 and 30%. Thickened fine tailings (ThFT) mean fluid fine tailings (FFT) or thin fine tailings (TFT) that have been thickened by removal of some of the aqueous content.
However, the solids content of such thickened fine tailings would not be above the liquid limit and therefore remain fluid.
Typically, the aqueous slurry comprises from 10% to 50% clay particles based on the total weight of solids. In general, the clay particles tend to be predominantly kaolinite and illite. The clay frequently also contains smectite and chlorite. The proportions of Date recue/Received Date 2020-04-06 the clay components of oil sands clays in marine deposits tend to vary according to depth within the deposit. Generally, illite species slightly dominates in the top end of the deposits. The smectite species are generally interlayered with either the kaolinite or illite species, and this tends to induce additional separation of particles.
The aluminosilicate nanoparticulate material has a molar ratio of aluminium to silicon from 0.7:1 to 3:1. Suitably, the molar ratio of aluminium to silicon may be from 0.8:1 to 2.9:1 or from 0.8:1 to 2.8:1. Desirably the aluminosilicate nanoparticulate material has a molar ratio of aluminium to silicon of from 0.8:1 to 2.5:1. Preferably the molar ratio of aluminium to silicon should be from 0.9:1 to 2.2:1 or 0.9:1 to 2.1:1 or 0.9:1 to 2:1, for instance from 1:1 t02:1.
The aluminosilicate nanoparticulate material may be prepared by combining an aqueous aluminate solution with an aqueous silicate solution. Typically, the aqueous aluminate can be an aqueous aluminate salt, for instance an alkali metal aluminate salt such as potassium aluminate, sodium aluminate or lithium aluminate. The aque-ous silicate solution can be an aqueous silicate salt, for instance an alkali metal sili-cate salt such as potassium silicate, sodium silicate or lithium silicate.
Suitably, the aqueous aluminate solution may be at a concentration of from 0.2% to 3%
(wt./wt. as A1203). Preferably, the concentration should be from 0.5% to 2%, more preferably from 0.75% to 1.5%. Suitably, the aqueous silicate solution may be at a concentra-tion of from 0.2% to 3% (wt./wt. as 5i02). Preferably, the concentration should be from 0.5% to 2%, more preferably from 0.75% to 1.5%.
The aqueous aluminate solution and the aqueous silicate solution desirably should be combined undercontinuous mixing conditions. This can be done by adding one of the aqueous solutions to the other aqueous solution which is in a vessel with con-stant stirring or agitation. Alternatively, the two aqueous solutions may be combined as to flowing streams followed by mixing. In this case the mixing may be achieved by employing an in-line static mixer or baffles or by employing in-line active mixing, for instance employing a CSTR (continuous stirred tank reactor).
The ratio of respective volumes and/or respective concentrations of aqueous alumi-nate solution and aqueous silicate solution should be chosen to be sufficient to pro-Date recue/Received Date 2020-04-06 vide a molar ratio of from 0.7:1 to 3:1 aluminium to silicon or any of the other more specific ratios within this range identified above.
The aqueous aluminate solution and the aqueous silicate solution desirably should 5 be combined at an ambient temperature, for instance from 10 C to 30 C, preferably 15 C to 25 C, suitably, from 17 C or 18 C to 22 C or 23 C. The reaction time may tend to vary according to the temperature at which the reaction is taking place. Typi-cally, there is an inverse relationship between reaction time and temperature in that at higher temperatures the reaction tends to be faster.
Suitably, the aluminosilicate nanoparticulate material consists predominantly of parti-cles of size below 50 nm. By predominantly we mean that greater than 50% by weight of the aluminosilicate nanoparticulate material. Typically, the aluminosilicate nanoparticulate material comprises from 55% to 100% by weight of particles of size below 50 nm. Often, the aluminosilicate nanoparticulate material comprises from 60% to 95%, desirably from 65% to 90%, or from 70% to 85% by weight of particles of size below 50 nm. Desirably, greater than 50% by weight of the aluminosilicate nanoparticulate material comprises particles of size below 30 nm, preferably below nm.
The aluminosilicate nanoparticulate material may comprise cage like structures that form a network comprising aluminium, silicon and oxygen atoms. The inventors be-lieve that the aluminosilicate nanoparticulate material may comprise zeolite such as Zeolite A or Faujasite or Sodalite or mixtures thereof. In general, there is expected to be a predominance of Sodalite aluminosilicate structures. By this we mean that it is likely that the aluminosilicate nanoparticulate material is made up from greater than 50% by weight of Sodalite. This is believed to be the case in view of the relatively higher ratio of aluminium to silicon. Suitably, the aluminosilicate nanoparticulate ma-terial comprises from 55 to 100% by weight of Sodalite, desirably from 60 to 100% by weight of Sodalite, typically from 70% to 95% by weight of Sodalite, usually from 75%
to 90% by weight of Sodalite. Sodalite is formed from p cages which are linked direct-ly through square faces. Sodalite is not strictly considered to be a zeolite.
Zeolite A is formed from p cages that are linked through square faces but with a D4R
spacer.
Date recue/Received Date 2020-04-06 Faujasite is also formed from p cages but linked through hexagonal faces but with a D6R spacer.
The polymeric flocculent (b) should be a polymer having an intrinsic viscosity of at least 5 dl/g (measured at 25 C in 1 M NaCI). The polymer may be non-ionic, anionic, amphoteric or cationic. Typically, this may be formed from ethylenically unsaturated monomers. In the case of a non-ionic polymeric flocculent the polymer may be de-rived from at least one non-ionic ethylenically unsaturated monomer. In the case of an anionic polymeric flocculent, the polymer may be derived from at least one anionic ethylenically unsaturated monomer, optionally including at least one ethylenically un-saturated non-ionic monomer. When the polymeric flocculent is cationic, it may be derived from one or more ethylenically unsaturated cationic monomers, optionally in combination with an ethylenically unsaturated non-ionic monomer. Where the poly-meric flocculent is amphoteric, this may be derived from ethylenically unsaturated anionic monomers and ethylenically unsaturated cationic monomers, optionally in combination with ethylenically unsaturated non-ionic monomers. Preferably, the pol-ymeric flocculent (b) is a polymer formed from repeating units derived from at least one ethylenically unsaturated monomer bearing an anionic group and optionally at least one ethylenically unsaturated non-ionic monomer.
Preferably still, the polymeric flocculent (b) is a water-soluble polymer derived from ethylenically unsaturated monomers selected from the group consisting of homopol-ymers of one or more ethylenically unsaturated acid monomers (or salts thereof); and copolymers formed from a monomer mixture comprising of (A) one or more ethyleni-cally unsaturated acid monomers (or salts thereof), (B) one or more ethylenically un-saturated non-ionic monomers selected from the group consisting of acrylamide, methacrylamide, hydroxy alkyl acrylate, vinyl acetate, vinyl alcohol, allyl alkyl ether, styrene and 01-8 alkyl acrylates (C) one or more other ethylenically unsaturated mon-omers different from (A) and (B). Ethylenically unsaturated monomers in category (C) may include other ethylenically unsaturated non-ionic monomers not specified in cat-egory (B) or alternatively it may be ethylenically unsaturated monomers bearing a cationic functional group.
Date recue/Received Date 2020-04-06 Suitable hydroxy alkyl acrylates as non-ionic comonomers may include any of hy-droxyethyl acrylate, hydroxypropyl acrylate and hydroxybutyl acrylate, and suitable hydroxyalkyl methacrylates include hydroxyethyl methacrylate, hydroxypropyl meth-acrylate and hydroxybutyl methacrylate. Suitable C1_8 alkyl acrylates as non-ionic comonomers may include methyl acrylate, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, n-butyl acrylate, sec-butyl acrylate, isobutyl acrylate, tert-butyl acrylate, ethylhexyl acrylate, n-octyl acrylate, or cyclohexyl acrylate.
Suitable allyl alkyl ethers as non-ionic monomers may include allyl methyl ether, ally!
ethyl ether, allyl n-propyl ether or allyl isopropyl ether.
The at least one ethylenically unsaturated acid monomers of category (A) may be any suitable anionic ethylenically unsaturated monomer. Suitable acid groups may include carboxylic acids, sulphonic acids, sulphuric acids, phosphoric acids or phos-phonic acids. By referring to the specific ethylenically unsaturated acid monomers we also include the corresponding salts thereof by this definition. We also include the corresponding anhydride of an acid group in the definition of ethylenically unsaturat-ed acid monomers. Suitable monomers in this category include acrylic acid, meth-acrylic acid, maleic acid, fumaric acid, itaconic acid, ethacrylic acid, crotonic acid, mono esters of ethylenically unsaturated dicarboxylic acids, such as mono methyl maleate, mono methyl fumarate, mono ethyl maleate, mono n-butyl maleate, and mono n-butyl fumarate, styrene carboxylic acids, maleic anhydride, itaconic anhy-dride, 2-acrylamido-2-methylpropylene acid, vinylsulfonic acid, allyl sulphonic acid, vinylphosphonic acid, 2-hydroxy ethyl methacrylate phosphate.
When the polymeric flocculent (b) is a polymer comprising components (A), (B) and contains component (C), desirably the other ethylenically unsaturated monomers (C) may be selected from one or more cationic monomers, provided that the overall ani-onic equivalent content is greater than the overall cationic equivalent content. Suite-bly, the one or more cationic monomers are included in the monomer mixture in an amount of up to 10 mol % total cationic monomer based on the total molar content of monomers in the monomer mixture.
Date recue/Received Date 2020-04-06 More preferably, the polymeric flocculent (b) is a copolymer of acrylamide with (meth)acrylic acid (or salt thereof) or a homopolymer of (meth)acrylic acid (or salt thereof).
The polymeric flocculent (b) may desirably be any anionic homopolymer or anionic copolymer that contains multivalent or monovalent counterion. Typically, the multiva-lent or monovalent counterion containing homopolymer or copolymer would be the multivalent or monovalent salt of the copolymer. Suitably, the multivalent counterion may be formed from alkaline earth metals, group Illa metals, transition metal etc.
Preferable multivalent counterions include magnesium ions, calcium ions, aluminium ions etc. Desirably, the monovalent counterion may be formed from alkali metals or ammonium. Preferable monovalent counterions include lithium ions, sodium ions, potassium ions, ammonium ions etc. Suitable homopolymers or copolymers contain-ing multivalent counterions may include repeating units of magnesium diacrylate, cal-cium diacrylate and aluminium triacrylate. Suitable copolymers containing monova-lent counterions include lithium acrylate, sodium acrylate, potassium acrylate and ammonium acrylate.
Desirably, the copolymer comprises repeating units of (meth)acrylamide and an eth-ylenically unsaturated anionic monomer contains a sodium counterion, a potassium counterion, an ammonium counterion, a calcium counterion or a magnesium counter-ion. Preferably, the copolymer contains a calcium counterion. More preferably, the copolymer is of acrylamide and an ethylenically unsaturated anionic monomer con-taining a calcium counterion.
Typically, the multivalent or monovalent counterion is contained in the homopolymer or copolymer of the polymeric flocculent (b) in a significant amount relative to the number of repeating units of the ethylenically unsaturated anionic monomer.
Normal-ly, the molar equivalent of multivalent or monovalent counterion to repeating anionic monomer units is at least 0.10:1. Suitably, the molar ratio equivalent may be from 0.15:1 to 1.6:1, normally from 0.20:1 to 1.2:1, preferably from 0.25:1 to 1:1.
The multivalent or monovalent counterion containing copolymer may be obtainable by copolymerisation of ethylenically unsaturated anionic monomer which is already in Date recue/Received Date 2020-04-06 association with the multivalent or monovalent counterion, for instance multivalent or monovalent cation salts of ethylenically unsaturated anionic monomer with (meth)acrylamide.
Thus, the multivalent or monovalent counterion containing copolymer, may be de-rived from a monomer mixture comprising a multivalent or monovalent cation salt of an ethylenically unsaturated anionic monomer and (meth)acrylamide. The ethyleni-cally unsaturated anionic monomer salt may be present in an amount in the range of from 5% to 95% by weight, based on the total weight of the monomers.
Desirably, the amounts of the respective monomers used to form the copolymer may be, for in-stance, from 5% to 95% by weight of multivalent or monovalent cation salt of an eth-ylenically unsaturated anionic monomer; and from 5% to 95% by weight of (meth) acrylamide.
Preferably, the amount of multivalent or monovalent cation salt of the ethylenically unsaturated anionic monomer may be from 5% to 85% by weight, such as from 5%
to 70% by weight, typically from 10% to 60% by weight, often from 15% to 50%
by weight, desirably from 20% to 45% by weight, for instance from 25% to 40% by weight; and the amount of (meth)acrylamide may be from 50% to 95% by weight, such as 30% to 95% by weight, typically from 40% to 90% by weight, often from 50%
to 85% by weight, desirably from 55% to 80% by weight, for instance from 60%
to 75% by weight.
Preferably, polymerisation is effected by reacting the aforementioned monomer mix-ture using redox initiators and/or thermal initiators. Typically, redox initiators include a reducing agent such as sodium sulphite, sodium metabisulphite, sulphur dioxide and an oxidising compound such as ammonium persulphate or a suitable peroxy com-pound, such as tertiary butyl hydroperoxide etc. Redox initiation may employ up to 10,000 ppm (based on weight of aqueous monomer) of each component of the redox couple. Preferably though, each component of the redox couple is often less than 1000 ppm, typically in the range from 1 to 100 ppm, normally in the range from 4 to 50 ppm. The ratio of reducing agent to oxidising agent may be from 10:1 to 1:10, Date recue/Received Date 2020-04-06 preferably in the range from 5:1 to 1:5, more preferably from 2:1 to 1:2 for instance around 1:1.
The polymerisation of the monomer mixture may be conducted by employing a ther-5 mal initiator alone or in combination with other initiator systems, for instance redox initiators. Thermal initiators would include suitable initiator compound that releases radicals at an elevated temperature, for instance azo compounds, such as azobisiso-butyronintrile (AIBN), 4,4'-azo bis-(4-cyanovalereic acid) (ACVA). Typically, thermal initiators are used in an amount of up to 10,000 ppm, based on weight of aqueous 10 monomer. In most cases, however, thermal initiators are used in the range from 100 to 5000 ppm, preferably from 200 to 2000 ppm, more preferably from 300 to 700 ppm, usually around from 400 to 600 ppm, based on the weight of the aqueous mon-omer mixture.
15 Typical methods of preparation of the multivalent or monovalent counterion contain-ing copolymer are given in WO 2017084986.
Intrinsic viscosity of the polymeric flocculent (b) may be determined by first preparing a stock solution. This may be achieved by placing 1.0 g of copolymer in a bottle and 20 adding 199 ml of deionised water. This mixture may then be mixed for 4 hours, for instance on a tumble wheel, at ambient temperature (25 C). Diluted solutions may then be prepared by, for instance, taking 0.0g, 4.0 g, 8.0 g, 12.0 g and 16.0 g, re-spectively, of the aforementioned stock solution and placing each into 100 ml volu-metric flasks. In each case, 50 ml of sodium chloride solution (2 M) should then be 25 added by pipette and the flask then filled to the 100 ml mark with deionised water and in each case the mixtures shaken for five minutes until homogenous. In each case, the respective diluted copolymer solutions are in turn transferred to an Ubbelohde viscometer and the measurement carried out at 25 C with the capillary viscometer Lauda iVisc. As such, the reduced specific viscosity of each of the dilute solution may be calculated and then extrapolated to determine the intrinsic viscosity of the poly-mer, as described in the literature.
Suitably, polymeric flocculent (b) may have an intrinsic viscosity in the range of from 5 to 30 dl/g, desirably from 5 to 25 dl/g, such as from 6 to 20 dl/g, for instance from 7 Date recue/Received Date 2020-04-06 to 20 dl/g, often from 9 to 19 dl/g, typically from 10 to 18 dl/g, normally from 12 to 18 dl/g.
In one preferred form, the polymeric flocculent (b) is water-soluble. By water-soluble we mean that the polymer has a gel content measurement of less than 50% gel.
The gel content measurement is described below.
The gel content may be determined by filtering a stock solution (preparation of a stock solution is described above in the method of measuring intrinsic viscosity) through a sieve with a 190 pm mesh size. The residue which stays in the filter is washed, recovered, dried (110 C) and weighed, and the percentage of undissolved polymer is calculated (weight of dry residue from the filter [g] /weight of dry polymer before filtration [g]). Where necessary, this provides a quantifiable confirmation of the visual solubility evaluation.
The optional cationic coagulant (c) is suitably a polymeric material having a weight average molar mass of from 10,000 to 2 million g/mol. Suitable polymers include polymers of diallyl dialkyl ammonium halide, for instance the homopolymers of diallyl dimethyl ammonium chloride (DADMAC). Suitable polymers may be formed from other cationic monomers such as quaternary ammonium salts of acrylate esters, for instance quaternary ammonium salts of dialkyl amino alkyl (meth) acrylate, such as the methyl chloride quaternary ammonium salt of dimethyl amino ethyl acrylate (DMAEA-q) or the methyl chloride quaternary ammonium salt of dimethyl amino ethyl methacrylate (DMAEMA-q). Further suitable polymers may be formed from cat-ionic monomers based on the quaternary ammonium salts of amino alkyl acryla-mides, including the quaternary ammonium salts of dialkyl amino alkyl (meth) acrylamides, for instance acrylamido propyl trimethylammonium chloride (APTAC) or methacrylamido propyl trimethylammonium chloride (MAPTAC). The aforesaid cati-onic monomers may be as homopolymers or as copolymers, for instance copoly-mers with acrylamide, such as DADMAC acrylamide copolymers, APTAC acrylamide copolymers, MAPTAC acrylamide copolymers, DMAEA-q acrylamide copolymers, and DMAEMA-q acrylamide copolymers.
Date recue/Received Date 2020-04-06 Other suitable polymers include polyamines, for instance partially or fully hydrolysed polyvinyl formamides containing repeating vinyl amine units. Other polymers include polyethyleneimines, polymers of alkyl amines with formaldehyde and/or epichlorohy-drin, and polycyandiamides.
Typical doses of the aluminosilicate nanoparticulate material (a) lie in the range of from 10 to 2000 g aluminosilicate nanoparticulate material (based on solids content) per tonne of solids content of the aqueous slurry. Desirably, this may be from 20 to 1500 g per tonne, suitably from 30 or 40 or 50 to 1000 g per ton, often from 75 to 750 g per tonne, frequently from 90 to 500 g per tonne, usually from 100 to 400 g per tonne.
Typical doses of the polymeric flocculent (b) may range from 20 to 2000 g of polymer per tonne of solids content of the aqueous slurry. Desirably, this may be from 40 or 50 to 1500 g per tonne, suitably from 75 to 1000 g per tonne, often from 90 to 750 g per tonne, usually from 100 to 500 g per tonne.
The exact doses of each of the two components may depend on the particular aque-ous slurry, including the particular particulate mineral material of the slurry and the solids content of the slurry. The optional cationic coagulant (c) may be applied to the aqueous suspension in doses in the ranges from 10 to 1000 g/tonne based on active weight of coagulant on dry weight of aqueous slurry, for instance in the range of from to 750 g/tonne, or from 50 to 500 g/tonne, or from 100 to 250 g/tonne.
25 Suitably, the particulate solids of the aqueous slurry comprise mineral solids. Typical-ly, the particulate solids may for instance contain filter cake solids or tailings. Often, the aqueous slurry may be an underflow from a gravimetric thickener, a thickened plant waste stream or alternatively may be an unthickened plant waste stream.
For instance, the aqueous slurry may comprise phosphate slimes, gold slimes or wastes from diamond processing. Typical aqueous slurries include slurries of mineral sands tailings, zinc ore tailings, lead ore tailings, copper ore tailings, silver ore tailings, ura-nium ore tailings, nickel ore tailings, iron ore tailings, coal fines tailings, oil sands tail-ings or red mud. The aqueous slurry suitable for treatment in accordance with the present invention may include the concentrated suspension from the final thickener Date recue/Received Date 2020-04-06 or wash stage of a mineral processing operation. Thus, the aqueous slurry may de-sirably result from a mineral processing operation. Preferably, the suspension com-prises tailings. Suitably, the particulate solids contained in the aqueous slurry may comprise at least some solids which are hydrophilic, for instance water swelling clays. More preferably, the particulate solids of the aqueous slurry may be derived from tailings from a mineral sands process, coal fines tailings, oil sands tailings, phosphate tailings or red mud.
The concentration of the aqueous slurry will tend to vary according to the particular type of substrate. In general, the aqueous slurry can often be a slurry of thickened tailings, for instance a thickened tailings suspension flowing as an underflow from a thickener, for instance a gravimetric thickener, or other stirred sedimentation vessel.
Suitably, the aqueous slurry may have a solids content in the range of from 30 to 70 % by total weight of aqueous slurry, for instance from 45% to 65% by weight.
Prefer-ably, the solids content of the aqueous slurry will often be from 30 to 50%, frequently from 30 to 45% by total weight of the aqueous slurry. When a pre-thickening stage occurs, the sand fraction (<44pm) solids may already be combined with the fine sol-ids fraction, or may be combined with the tailings stream subsequently, after the thickening stage.
Suitably, the aqueous slurry containing the particulate material may be an underflow stream which flows from a sedimentation vessel in which a first suspension of the particulate mineral material is separated into a supernatant layer comprising an aqueous liquor and a thickened layer which is removed from the vessel as an under-flow. It would be this underflow which would be subjected to the treatment according to the present invention. It would not be possible to achieve the objectives of the in-vention by adapting the separation in a conventional sedimentation vessel as the yield stress of the thickened layer would be so high that it would be impossible to stir the thickened layer or remove the thickened layer from the conventional sedimenta-tion vessel as an underflow. Furthermore, such solids would not be able to flow as an underflow from the vessel.
Aqueous slurries may not necessarily have a sand to fines ratio within the range of greater than 1:1 to 3:1. For instance, whole tailings (WT) have sand to fines ratios of Date recue/Received Date 2020-04-06 greater than 4:1 and mostly tend to be greater than 5:1 and may be as high as 20:1.
Composite tailings (CT) also have high sand to fines ratios typically more than 3:1 and in some cases more than 5:1 and may be as high as 6:1 or 7:1. On the other hand fluid fines tailings (FFT), thin fines tailings (TFT), thickened fines tailings (ThFT) and mature fines tailings (MFT) all tend to have very low sand to fines ratios.
FFT tend to have sand to fine ratios significantly below 1:1 and MFT tend to have much lower sand contents typically less than 0.3:1, for instance less than 0.25:1.
The sand to fines ratios of aqueous slurries not having a sand to fines ratio within the range of greater than 1:1 to 3:1, or greater than 1:1 to 2:1 may be adjusted to a sand to fines ratio within the scope of the present invention, including any of the preferred sand to fines ratios recited herein.
For aqueous slurries where the sand to fines ratios fall below 1:1, for instance, as in .. the case of MFT slurries, FFT slurries, TFT slurries and ThFT slurries, the sand to fines ratio may be increased. One way of achieving this is to combine sand with the aforesaid MFT, FFT, TFT or ThFT slurries. The sand may be a concentrated sand fraction, for instance the underflow from a cyclone processing whole tailings (VVT).
Another way of carrying this out would be to mix the aforesaid MFT, FFT, TFT
or ThFT slurries with whole tailings (WT). In both cases the proportions of sand fraction or whole tailings to the MFT, FFT, TFT or ThFT slurries should be such that the so formed composite tailings (CT) should have a sand to fines ratio of from greater than 1:1 to 3:1, preferably from 1.1:1 to 2.9:1, more preferably from 1.2:1 to 2.8:1 and more preferably still from 1.2:1 to 2.7:1 and yet more preferably from 1.2 to 1 to 2.5:1.
Where the aqueous slurries have a sand to fines ratio greater than 3:1, preferably greater than 2.8:1 and more preferably greater than 2.7:1, as in the case of whole tailings (WT) or even some conventional composite tailings (CT), the adjustment of .. the sand to fines ratio should be a reduction of the sand content. One way of con-ducting this would be to pass whole tailings (WT) through a screen which filters out large coarse size sand particles such as greater than 120 pm or preferably greater than 100 pm. This may also be achieved by passing the aqueous slurry, for instance whole tailings, through a cyclone which cuts at the desired particle size, for instance Date recue/Received Date 2020-04-06 120 pm or 100 pm, to remove the larger particle size sand. This removal of some of the sand would serve to reduce the sand to fines ratio to the desired level.
There are a number of ways in which the treatment system can be applied to the aqueous slurry including addition to any of the components forming the aqueous 5 slurry such as precursor slurries or other components such as sand.
In accordance with one aspect of the inventive process the aqueous slurry may be formed from a first precursor aqueous slurry in which the sand to fines ratio is below 1:1, suitably below 0.7:1, for instance below 0.5:1, and the sand to fines ratio may be 10 .. adjusted to increase the sand to fines ratio by either, (a) combining the first precursor aqueous slurry with sand; and/or (b) combining the first precursor aqueous slurry with a second precursor aque-ous slurry, which second precursor aqueous slurry has a sand to fines ratio of greater than 3:1, suitably greater than 4:1 and especially suitably greater than 5:1, 15 .. and thereby forming the aqueous slurry, in which the treatment system or components thereof desirably would be applied to any one or more of the first precursor aqueous slurry, the sand component, the sec-ond precursor aqueous slurry and/or the aqueous slurry.
20 In one suitable embodiment of this aspect of the invention the sand in (a) may be in the form of a sand stream, preferably the underflow sand stream from a cyclone pro-cessing whole tailings (WT). Desirably, the first precursor aqueous slurry is selected from the group consisting of mature fines tailings (MFT), fluid fines tailings (FFT), thin fines tailings (TFT), thickened fines tailings (ThFT). The second precursor aqueous 25 .. slurry may desirably be whole tailings (WT).
In accordance with a further aspect of the inventive process the aqueous slurry may be formed from a second precursor aqueous slurry in which the sand to fines ratio is greater than 3:1, suitably greater than 4:1 and especially suitably greater than 5:1, 30 and the sand to fines ratio desirably would be adjusted to decrease the sand to fines ratio by separating sand particles having a particle size greater than a predetermined size limit, preferably greater than 100 pm, from the second precursor aqueous slurry thereby, and thereby forming the aqueous slurry, Date recue/Received Date 2020-04-06 in which the treatment system or components thereof are applied to any one or more of the second precursor aqueous slurry and/or the aqueous slurry. The predeter-mined size limit may be set at any level sufficient to remove sufficient sand particles in order to provide an aqueous slurry of the desired sand to fines ratio in accordance with the invention. This may, for instance, be greater than 100 pm or in some cases greater than 110 pm or in other cases greater than 120 pm, depending upon the par-ticle size distribution and sand content of the second precursor aqueous slurry. The second precursor aqueous slurry may, for instance, be whole tailings (WT).
Preferably, the separation of the sand from the second precursor aqueous slurry is conducted using a cyclone or by use of a screen having a mesh size sufficient to re-move the sand particles having a particle size greater than the predetermined size limit.
Desirably, the aqueous slurry of particulate material comprises flowing as slurry of mature fines tailings (MFT) and/or fluid fines tailings (FFT) and/or thickened fines tail-ings (ThFT) along a conduit and in which a slurry of sand is combined with the slurry of mature fines tailings and/or fluid fines tailings and/or thickened fines tailings (ThFT) to provide a combined tailings stream (CbT) having the desired sand to fines ratio of from greater than 1:1 to 3:1, wherein the components of the treatment system are applied to (i) the mature fines tailings and/or fluid fines tailings and/or thickened fines tailings (ThFT), and/or (ii) the combined tailings (CbT) stream, and in which the so treated combined tailings (CbT) stream is fed to a deposition area.
Preferably the aluminosilicate nanoparticulate material (a) is either fed into the slurry of MFT and/or FFT and/or ThFT, fed into the sand slurry; or fed into the combined tailings stream (CbT) and thereafter the polymeric flocculant (b) is added to the so treated combined tailings stream (CbT). Optionally, the cationic coagulant (c) may be added to the combined tailings stream (CbT) either before, or preferably after the addition of the flocculant (b).
It may be desirable in some cases to add the polymeric flocculant (b) to the aqueous slurry as it exits the conduit for instance pipeline. In other cases, it may be desirable to add the flocculant prior to the aqueous slurry exiting the outlet of the conduit, or more specifically pipeline, for instance less than 100 m, less than 50 m and desirably Date recue/Received Date 2020-04-06 less than 10 m from the outlet. In general, the polymeric flocculant (b) desirably would be added to the aqueous slurry in the conduit or pipeline and close to the out-let, for instance less than 50 m from the outlet, for instance from 0.1 to 30 m from the outlet, or from 0.5 to 20 m from the outlet, or from 1 to 10 m from the outlet, or even from 1 to 5 m from the outlet.
Typically, the aqueous slurry is transferred by pumping along a conduit to a deposi-tion area. The conduit can be any convenient means for transferring the aqueous slurry to the deposition area and may, for instance, be a pipeline or even a trench.
The deposition area may be a tailings dam or lagoon or may be adjacent to a tailings dam or lagoon, or preferably an open mining void or pit.
Normally the aqueous slurry would be transferred continuously to the deposition area i.e. without interruption of the flow. However, in some cases it may be desirable to transfer the aqueous slurry first to a holding vessel or pond, before being transferred to the deposition area.
Suitably, the aqueous slurry is transferred to the deposition area through a conduit, for instance a pipeline. Normally, such a conduit, for instance pipeline, would have an outlet from which the aqueous slurry exits as it flows to the deposition area. Typi-cally, the outlet of the conduit, for instance pipeline, is at the deposition area or may be close to the deposition area, for instance less than 20 m, usually less than 10 m and desirably less than 5 m from the deposition area. In such cases where the con-duit or more specifically pipeline is close to the deposition area, the aqueous slurry should be able to flow into the deposition area.
Desirably the so treated combined tailings stream (CbT) is fed into a void or im-poundment at the deposition area, in which the void or impoundment has a depth of at least 5 m and the deposited solids are allowed to separate from the released su-pernatant liquid and consolidate. Desirably, the separated solids form a relatively homogeneous deposit with minimal segregation of the fines and sand particles.
The void or impoundment area may have a depth of at least 10 m, for instance at least 15 m or suitably at least 20 m. The depth may be as much as 50 m or even as much as 75 m or as much as 100 m or more. Thus, the void or impoundment may have a Date recue/Received Date 2020-04-06 depth in the range of from 5 m to 100 m, from 10 m to 75 m, from 15 m to 50 m or from 20 m to 40 m. This method of deep void disposal is sometimes referred to as Deep Pour. Deep Pour technique is believed by the inventors to be analogous to the technique described in Section 4 of the COSIA document entitled, "Deep Fines-Dominated (Cohesive) Deposits" and available on the COSIA website (httbs://www.cosia.ca/ubloads/documents/id7/TechGuideFluidTailindsMdmt Aud201 The supernatant liquid separated from the so treated slurry should form above the particulate solids deposited in the void or impoundment. Generally, the supernatant liquid may desirably be continually or periodically removed from the void or im-poundment area.
Alternatively, the so treated combined tailings stream may be fed onto a beach sur-face at the deposition area and form thin layers of newly deposited beach material which dewaters through drainage and evaporation. The beached surface may have an angle of incline of from 0.5 and 100 .
In some instances, in accordance with the invention, the deposition of the solids is controlled to build up relatively narrow bands of tailings which can also dewater quickly through evaporation, prior to adding a new layer of treated waste material on top. This technique of using narrow band disposal may sometimes be referred to as "Thin Lift". In general, the deposition of the so treated aqueous slurry may be onto a beached surface, for instance as described in the previous paragraph. The inventors believe that the "Thin Lift" method of disposal in regard to the oil sands industry is analogous to the technique described in section 3 of the aforementioned COSIA
document, entitled, "Thin Layered Fines Dominated Deposits". This document uses from 0.1 to 0.5 m as a typical thickness for each lift.
Outside the oil sands industry, for instance in the alumina industry, the invention may also be employed by the deposition of thin layers, having a thickness of up to 0.5 m.
For instance, the so treated material at a deposition area, such as onto a beached surface, as described above, the analogous technique may be referred to as "Dry Stacking". A general description for this type of technique in the alumina industry is Date recue/Received Date 2020-04-06 described, particularly in section 3, in the paper given by DJ Cooling (Alcoa World Alumina Australia) to the Paste 2007 Conference in Perth, Australia. The paper is entitled, "Improving the Sustainability of Residue Management Practices ¨
Alcoa World Alumina Australia", Australian Centre for Geo-mechanics, Perth, ISBN 0-9756756-7-2.
In one aspect of the invention the treatment system may comprise adding the alumi-nosilicate nanoparticulate material (a) to the aqueous slurry of particulate material before adding the polymeric flocculent (b). Typically, aqueous slurry of particulate material may first be treated by the addition of the aluminosilicate nanoparticulate material (a) and then the so treated slurry subjected to a mixing stage followed by the addition of the polymeric flocculent (b). Alternatively, the aqueous slurry of particulate material may be treated by the addition of the whole treatment system followed by subjecting the so treated aqueous slurry to a mixing stage. Nevertheless, it may be desirable that the aqueous slurry of particulate material is subjected to a mixing stage after the addition of each of the aluminosilicate nanoparticulate material (a) and the polymeric flocculent (b) of the treatment system. Optionally, cationic coagulant (c) may be added between the addition of the aluminosilicate nanoparticulate material (a) and the polymeric flocculent (b), simultaneously with the addition of the polymeric flocculent (b) or subsequent to the addition of the polymeric flocculent (b).
The aluminosilicate nanoparticulate material (a) may typically be added as an aque-ous formulation to the aqueous slurry.
Typically, the aluminosilicate nanoparticulate material should be produced near to where it is being used. The aluminosilicate nanoparticulate material should be used soon after it has been produced. This is because the aluminosilicate nanoparticulate material ages with time. The ageing of the material results in the particles tending to grow and/or agglomerate into polyparticulate networks. As the particles grow and/or agglomerate the surface area for a given mass of the aluminosilicate tends to reduce.
In addition, the viscosity of the aqueous aluminosilicate material may increase. Even-tually, this may form a gel. Where the aqueous aluminosilicate nanoparticulate mate-rial is diluted sufficiently, for instance by quenching with water, the formation of a gel may be avoided, however eventually the aqueous aluminosilicate composition may Date recue/Received Date 2020-04-06 tend to become turbid with gradual precipitation of the aluminosilicate. Where the aluminosilicate polyparticulate material ages extensively, the effectiveness of the ma-terial may reduce. Suitably, the aluminosilicate nanoparticulate material may be pro-duced and dosed directly into the aqueous slurry to be treated as part of the treat-5 ment system. Ideally, the aluminosilicate nanoparticulate material should be used within 24 hours of being produced, desirably within 12 hours, usually within 9 hours, often within 6 hours, preferably within 2 hours, more preferably within 1 hour, and most preferably within 30 minutes.
10 Desirably, the aluminosilicate nanoparticulate material may be produced at the same location as the process for treating the aqueous slurry. The aluminosilicate nanopar-ticulate material may be produced in apparatus that comprises storage facilities for each of the concentrated aluminate and silicate aqueous solutions, a means for combining the two solutions, a means for mixing and reacting the two solutions and a 15 .. means for storage of the resultant aluminosilicate nanoparticulate material. This ap-paratus may be a temporary apparatus which can be assembled by installing the components at the required location or the apparatus may be portable in that it is constructed in such a way that allows the apparatus to be moved from one location to another as required. A suitable apparatus for conveniently delivering the aluminosili-20 .. cate nanoparticulate material at the required location may comprise vessels for each of the aluminate solution and the silicate solution, conduits from each of the vessels to convey the two solutions leading to a device for combining the two solutions.
The two solutions may be conveyed along the conduits by means of pumping devic-25 es or if appropriate by means of gravity. The means for combining the two solutions may be by feeding the aluminate and silicate solutions into a single conduit where the two solutions can combine. This may be, for instance, a Y connection or a T
connec-tion. Preferably the concentrated aluminate and silicate solutions will be prediluted prior to the point where the two components are combined. The conduit containing 30 the mixture of two solutions may contain internal mixing devices, for instance a static mixer and/or baffles and/or a mixing unit such as a continuous stirred tank reactor (CSTR).
Date recue/Received Date 2020-04-06 Alternatively, the means for combining the two solutions may be a separate vessel into which the two conduits carrying the respective aluminate and silicate solutions connect. The contents of the combined and mixed aluminate and silicate solutions should react relatively quickly to form the aluminosilicate nanoparticulate material.
Speed of reaction may be from 5 seconds to 5 minutes, for instance from 10 seconds to 3 minutes, such as from 20 seconds to 1 minute. The speed of the reaction may be influenced to some extent by the temperature of the environment where the alu-minate and silicate are reacted. The so formed aluminosilicate nanoparticulate mate-rial may then be fed into a suitable storage vessel which may be stirred.
Preferably the reaction mixture may be further diluted as it is transferred into the storage tank, to slow down any further growth and aggregation of the nanoparticles.
The produced aluminosilicate nanoparticulate material may be dosed directly into the aqueous slurry to be treated as part of the treatment system. This may be achieved using suitable dosing equipment which is already available commercially and well known in the art.
The concentration of the aluminosilicate nanoparticulate material (a) may be any suitable concentration in which it would be effective in the treatment and which is easily fed into and to mix with the aqueous slurry. Suitably, the aluminosilicate nano-particulate material should be at a concentration from 0.2 % to 5 %, often from 0.5 %
to 2 % and preferably from 0.5% to 1.5% based on the weight of the solids of the aluminosilicate on the weight of the aqueous composition containing the aluminosili-cate.
The flocculent (b) may be added as an aqueous solution or as dry particles directly to the aqueous slurry.
The aqueous solution of flocculent (b) is typically obtained by dissolving the polymer in water or by diluting a more concentrated solution of the polymer. Generally solid particulate polymer, for instance in the form of powder, beads or substantially spheri-cal particles, is dispersed in water and allowed to dissolve with agitation.
This may be achieved using conventional make up equipment. Desirably, the polymer solution can be prepared using the Auto Jet Wet (trademark) supplied by BASF, for example Date recue/Received Date 2020-04-06 as described in GB 1501938. The polymer solution may also be prepared according to any of the disclosures of US 4518261, US 5857773, US 6039470, US 5580168, US 5540499, US 5164429, US 5344619. The polymer solution may even be pre-pared using polymer slicing/shearing equipment, for instance as described by US
4529794, US 4874588, or even any of the disclosures CA 2667277, CA 2667281, CA
2700239, CA 2700244, CA 2775168, CA 2787175, CA 2821558 or US 2009/095688.
Alternatively, the polymer may be supplied in the form of a reverse phase emulsion or dispersion which can then be inverted into water by conventional techniques.
The concentration of the aqueous solution of the polymer of flocculent (b) may be any suitable concentration which would facilitate the polymer solution to be fed into and mix with the aqueous slurry. Although it is conceivable that the aqueous polymer solution may be 5% weight/volume or more, it is usual that the concentration be less than 5% weight/volume. Typically, the polymer solution will tend to be below 3%
weight/volume. Usually the aqueous polymer concentration will be at least 0.01%
weight/volume. Suitably the aqueous polymer concentration may be from 0.01% to 5% weight/volume, typically from 0.02% to 3%, often from 0.05% to 1%.
The polymeric cationic coagulant (c) may be added as an aqueous solution or as dry particles to the aqueous slurry.
Typically, the cationic coagulant is manufactured directly as an aqueous solution, or it may be in the form of dry particles and then pre-dissolved in water to prepare an aqueous solution. In the latter case, generally the solid particulate cationic coagulant, for instance in the form of powder, beads or substantially spherical particles, can be dispersed in water and allowed to dissolve with agitation. This may be achieved us-ing suitable make-up equipment (as described above in regard to flocculent (b)) It is also possible that the cationic coagulant is manufactured directly as an aqueous so-lution of higher concentration, and then diluted with water and mixing to form a lower concentration aqueous solution.
The concentration of the aqueous solution of the cationic coagulant (c) may be any suitable concentration which would facilitate the coagulant solution to be fed into and to mix with the aqueous slurry. Although it is conceivable that the aqueous cationic Date recue/Received Date 2020-04-06 coagulant concentration solution may be greater than 50% weight/volume, it is usual that the concentration be equal to or lower than 50% weight/volume. Usually the cati-onic coagulant solution will be from 0.01% to 50% weight/volume. Suitably, the aqueous cationic coagulant solution concentration will be from 0.1% to 30%, often from 1 to 10%.
The examples that follow are intended to illustrate the invention without in any way being limiting.
Date recue/Received Date 2020-04-06 Examples Description of the flocculants used in the examples:
Flocculant A is a copolymer of sodium acrylate and acrylamide having a weight ratio of 40/60 and exhibiting an intrinsic viscosity of 10 dl/g and in the form of a bead having been prepared by traditional reverse-phase suspension polymerisation.
Flocculant B is a copolymer of calcium diacrylate and acrylamide having a weight ratio of 40/60 and exhibiting an intrinsic viscosity of 15 dl/g in the form of a powder and prepared according to Example 1 of W02017084986.
Example 1 ¨ Preparation of alumina-silicate nanoparticles with a 2:1 Al:Si molar ratio (Product A) Reagents:
Liquid sodium aluminate (20 c/owt/wt as A1203) Liquid sodium silicate solution (44 c/owt/wt total solids, 32 c/owt/wt as SiO2) Deionised water (at 20 C) = (i) Prepare a dilute solution of sodium aluminate by adding 10.2g of liquid sodium aluminate to 167g of deionised water, whilst mixing with high shear for 30 seconds.
= (ii) Prepare a dilute solution of sodium silicate by adding 3.7g of liquid sodium silicate to 167g of deionised water, whilst mixing with high shear for 30 seconds.
= (iii) Place the dilutie solution of sodium silicate (step i) into a 600 ml glass beaker, set up with an overhead electric stirrer and an axial flow turbine four blade impeller. Start the impellor at 1100 rpm and add the dilute solution of sodium aluminate (step ii). After 10 seconds, reduce the impellor speed to 250 rpm.
After a further 3 minutes, turn off the agitator.
= (iv) Immediately transfer the mixture prepared (step iii) into a 2000 ml glass beaker containing 660 ml of deionised water. Stir the final mixture to ensure that it Date recue/Received Date 2020-04-06 is completely homogeneous. Product A is now ready for immediate use in the application tests.
=
Example 2 ¨ Preparation of alumina-silicate nanoparticles with a 1.5:1 Al:Si molar 5 ratio (Product B) Using the method as described in Example 1 above, except for varying the quantities of the following reagents:
i. 9.1g of liquid sodium aluminate ii. 4.4g of liquid sodium silicate Example 3 ¨ Preparation of alumina-silicate nanoparticles with a 1:1 Al:Si molar ratio (Product C) Using the method as described in Example 1 above, except for varying the quantities of the following reagents:
i. 7.5g of liquid sodium aluminate ii. 5.5g of liquid sodium silicate Example 4 ¨ Preparation of alumina-silicate nanoparticles with a 0.5:1 Al:Si molar ratio (Product D) Using the method as described in Example 1 above, except for varying the quantities of the following reagents:
i. 4.8g of liquid sodium aluminate ii. 7.1g of liquid sodium silicate Example 5 ¨ treatment of tailings from an oilsands, bitumen extraction process.
Oilsands process water, as used below, typically has a similar chemical composition to the aqueous phase of the MFT slurry used to prepared the test substrate.
A substrate sample with 2:1 SFR (sand/fines ratio) was prepared by blending parts (wt) of MFT obtained from an oilsands operation, and 75 parts (wt) of wet coarse tailings to yield a combined tailings material of the following composition:
Sand (particulates > 44 pm) 40.1 % wt Fines (particulates < 44 pm) 20.0 % wt Process Water 39.9 % wt Date recue/Received Date 2020-04-06 The combined tailings material was mixed continuously to ensure homogeneity, and sub-sampled into individual aliquots (50 g) for subsequent testing.
Part 1 ¨ testing for substrate dewaterability and consolidation:
Product (s) containing alumina-silicate nanoparticles, were freshly prepared, as described in Examples 1 ¨ 4 above . Flocculent polymer solutions were prepared to contain 0.5 %wt/vol of polymer in oilsands process water.
The 50 g aliquot of the combined tailings substrate is placed in a 120 ml beaker and mixed with a flat blade stirrer at 400 rpm. After 10 seconds, the required amount of the 0.5% wt/vol alumina-silicate nanoparticle Product is added and subsequently, after 10 seconds, the required amount of 0.5% wt/vol flocculent solution is added, and mixing is continued until the sample is conditioned to the visual point of optimum flocculation / net water release (NWR), at which time the mixer is stopped.
The mixing time after the flocculent addition required to reach the point of optimum conditioning is recorded, and it may differ significantly for different types and dosages of aluminosilicate nanoparticulate material and flocculent.
After conditioning, the treated substrate is transferred into a pressure filter apparatus consisting of a cylindrical chamber of diameter 3.25 cm, fitted with fine filter media at one end, and a solid sliding piston at the other. (see fig 1). A force equal to an internal pressure of 6 psi is then applied to the piston for a period of 10 mins, during which the water expelled through the filter media is collected. The particulate solids content of the release water was determined gravimetrically by drying at 110 C
for 2 hrs. The dry weight value obtained was adjusted for the electrolyte content of the process water (0.27 %wt/vol). The moisture content of the filtercake was determined by drying at 110 C for 24 hours.
Part 2 ¨ testing for fines capture during sub-aqueous deposition 50 g aliquot of the combined tailings substrate is treated with aluminosilicate nanoparticulate material and flocculent as has been previously described in Part 1.
After conditioning, the treated substrate is transferred into a 250 ml measuring cylinder which already contains 200 ml of water. The cylinder is then inverted vigorously three times to disperse the treated substrate into the bulk of the water.
Date recue/Received Date 2020-04-06 The cylinder is then left to stand for 10 mins before sampling the supernatant water and measuring the residual turbidity.
Table 1: 2:1 SFR Oilsands Tailings with Flocculent A (see Fig 2 & 3) Part 1 Part 2 Product A Flocculent A
Mixing Time Cake Solids Mixing Time Turbidity Dose (g/t) Dose (kg/t) (s) (%wt) (s) (NTU) 0 0.67 36.1 60.9 42.5 719 33 0.67 44.3 66.3 42.8 77 67 0.67 50.4 76.5 49.0 40 100 0.67 49.9 77.4 40.9 37 133 0.67 55.0 77.8 41.5 40 166 0.67 58.8 78.3 50.5 57 Table 2: 2:1 SFR Oilsands Tailings with Flocculent B (see Fig 4 & 5) Part 1 Part 2 Product A Flocculent B
Mixing Time Cake Solids Mixing Time Turbidity Dose (g/t) Dose (kg/t) (s) (%wt) (s) (NTU) 0 0.73 59.0 62.5 46.8 1080 33 0.73 43.1 59.4 49.2 941 67 0.73 55.9 60.9 51.1 1070 100 0.73 60.0 67.6 56.0 102 133 0.73 59.4 65.9 59.6 24 166 0.73 56.3 70.4 59.7 28 The results show that for the substrate mixture with a 2:1 SFR, the pre-addition of Product A significantly reduced the residual moisture in the dewatered solids, and improved the retention and capture of fine particles during both dewatering and sub-aqueous deposition when tested in conjunction with either Flocculent A or Flocculent B. For example, when pre-treated with 100 g/t of Product A, the tailings dewatered to yield a final solids of 77.4% compared to 60.9% for the tailings treated with Flocculent A alone. Similarly, the fine capture improved as indicated by residual Date recue/Received Date 2020-04-06 turbidity; 102 NTU with the pre-treatment compared to 1070 NTU when the addition of Product A is omitted.
Example 6 - Treatment of tailings from an oilsands, bitumen extraction process Testing was carried out as previously described in example 5 above, except that a substrate sample with 1.5:1 SFR (sand/fines ratio) was prepared by blending parts (wt) of MFT, and 55 parts (wt) of wet coarse tailings to yield a combined tailings material of the following composition:
Sand (particulates > 44 pm) 22.8 %wt Fines (particulates < 44 pm) 34.1 %wt Process Water 43.1 %wt Table 3: 1.5:1 SFR Oilsands Tailings with Flocculent A (see Fig 6 & 7) Part 1 Part 2 Product A Flocculent A
Mixing Time Cake Solids Mixing Time Turbidity Dose (g/t) Dose (kg/t) (s) (%wt) (s) (NTU) 0 0.68 42.6 54.5 43.6 1430 0 0.71 42.9 55.2 45.8 1020 0 0.82 47.8 71.2 49.3 61 0 0.89 62.1 73.4 54.4 50 36 0.71 38.8 54.9 47.0 153 71 0.71 45.4 67.4 43.2 90 107 0.71 61.3 73.9 40.0 52 143 0.71 58.2 76.7 46.7 69 179 0.71 58.2 74.6 45.7 70 214 0.71 44.4 71.2 55.7 49 The results show that for the substrate mixture with a 1.5:1 SFR, the pre-addition of Product A significantly reduced the residual moisture in the dewatered solids, and improved the retention and capture of fine particles during both dewatering and sub-aqueous deposition when tested in conjunction with Flocculent A. Further, increasing the dosage of Flocculent A without the pre-treatment with Product A, for example Date recue/Received Date 2020-04-06 from 0.71 kg/t to 0.89 kg/t achieved inferior dewatering when compared to a pre-treatment of 143 g/t Product A, and 0.71 kg/t of Flocculant A.
Example 7 - Treatment of tailings from an oilsands, bitumen extraction process Testing was carried out as previously described in example 5 above, except that a substrate sample with 1:1 SFR (sand/fines ratio) was prepared by blending 100 parts (wt) of MFT, and 37.5 parts (wt) of wet coarse tailings to yield a combined tailings material of the following composition:
Sand (particulates > 44 pm) 25.9 %wt Fines (particulates < 44 pm) 25.9 %wt Process Water 48.2 %wt Table 4: 1:1 SFR Oilsands Tailings with Flocculant A (see Fig 8 & 9) Part 1 Part 2 Product A Flocculant A
Mixing Time Cake Solids Mixing Time Turbidity Dose (g/t) Dose (kg/t) (s) (%wt) (s) (NTU) 0 0.88 49.0 54.1 47.8 741 0 0.96 55.2 64.6 53.3 228 0 1.04 65.7 57.8 72.0 88 40 0.88 60.3 66.3 53.6 207 80 0.88 57.5 59.3 44.3 105 120 0.88 60.3 58.7 41.2 96 160 0.88 54.4 59.3 62.2 149 199 0.88 58.0 57.3 53.5 146 Date recue/Received Date 2020-04-06 Table 5: 1:1 SFR Oilsands Tailings with Flocculant B (see Fig 10 & 11) Part 1 Part 2 Product A Flocculant B
Mixing Time Cake Solids Mixing Time Turbidity Dose (g/t) Dose (kg/t) (s) (%wt) (s) (NTU) 0 1.00 68.7 47.8 56.2 1360 0 1.04 74.1 48.1 79.4 298 0 1.08 102.0 55.4 94.8 382 0 1.12 110.0 55.7 95.6 307 120 1.00 68.1 52.3 70.0 248 160 1.00 80.1 57.7 85.7 128 199 1.00 108.7 56.3 78.4 72 239 1.00 71.4 58.9 88.6 109 319 1.00 112.6 57.1 105.0 119 The results show that for the substrate mixture with a 1:1 SFR, the pre-addition of Product A with either Flocculant A or Flocculant B, achieved improvements with both 5 higher cake solids, and lower turbidity, than was achieved by either flocculant alone.
For example, Flocculant A alone achieved a maximum cake solids of 64.6% and turbidity of 228 NTU at a dose of 0.96 kg/t, whereas a pre-treatment dose of 40 g/t, and 0.88 kg/t Flocculant A achieved a maximum cake solids of 66.3% and turbidity of 207 NTU. Similarly, 1.12 kg/t of Flocculant B alone achieved a maximum cake solids 10 of 55.7% and turbidity of 307 NTU, whereas a pre-treatment dose of 160 g/t, and 1.0 kg/t Flocculant B achieved a maximum cake solids of 57.7% and turbidity of 128 NTU.
Example 8 - Treatment of tailings from an oilsands, bitumen extraction process 15 Testing was carried out as previously described in example 5 above, except that a substrate sample with 2:1 SFR (sand/fines ratio) was prepared by blending 100 parts (wt) of MFT, and 75 parts (wt) of wet coarse tailings to yield a combined tailings material of the following composition:
Sand (particulates > 44 pm) 39.8 %wt 20 Fines (particulates < 44 pm) 19.9 %wt Process Water 40.3 %wt Date recue/Received Date 2020-04-06 Note - the M FT used in example 8 was a different sample to the M FT tailings substrated used in the previous examples (5 - 7) Table 6: 2:1 SFR Oilsands Tailings with Flocculent B (see Fig 12 & 13) Pre-treatment Part 1 Part 2 Flocculent Cake Dose Mixing Mixing Turbidity Product B (kg/t) Solids (g/t) Time (s) Time (s) (NTU) (%wt) n/a 0.35 53.5 65.7 32.0 5940 n/a 0.4 46.1 75.6 39.5 3450 A 17 0.35 49.5 64.9 37.8 3680 A 34 0.35 52.7 78 36.5 1500 A 67 0.35 48.1 78.5 n/a 751 A 101 0.35 61.9 77.6 43.4 843 A 134 0.35 67.6 77.7 43.7 122 B 17 0.4 42.8 81.6 NT NT
B 34 0.35 NT NT 37.7 3060 B 34 0.4 47.7 81.4 NT NT
B 67 0.35 NT NT 40.1 1520 B 67 0.4 58.8 81.7 NT NT
B 134 0.35 NT NT 45.5 226 B 134 0.4 41.3 80.7 NT NT
C 34 0.35 NT NT 36.5 2060 C 34 0.40 55.5 80.9 NT NT
C 67 0.35 NT NT 40.3 1190 C 67 0.40 49.4 81.8 NT NT
C 101 0.35 NT NT 39.8 522 C 101 0.40 53.9 81.2 NT NT
C 134 0.35 NT NT 40.8 297 C 134 0.40 54.4 72.1 NT NT
D 17 0.35 49.5 64.9 39.4 3010 D 34 0.35 52.7 78.0 41.0 1340 D 67 0.35 48.1 78.5 35.2 1400 Date recue/Received Date 2020-04-06 101 0.35 61.9 77.6 40.1 1200 134 0.35 67.6 77.7 41.6 161 NT = not tested The results show that for all the different Al:Si ratios tested, the pre-treatment with the aluminasilicate nanoparticles both imcreased the cake solids, and reduced the measured turbidity when compared to the relevant control tests.
Date recue/Received Date 2020-04-06

Claims (39)

Claims

1. A process for separating solids from an aqueous slurry containing particulate material, which particulate material comprises sand particles and fines particles and contains clay particles, which aqueous suspension has a solids content of from 30 to 70% by weight and a sand to fines ratio of from greater than 1:1 to 3:1, which process comprises applying a treatment system to the aqueous slurry to cause flocculation of the particulate material, and subsequently separating the so formed flocculated particulate material as solids from the slurry, in which the treatment system comprises (a) at least one aluminosilicate nanoparticulate material, in which the molar ratio of aluminium to silicon is from 0.7:1 to 3:1;
(b) at least one polymeric flocculant, which has an intrinsic viscosity of at least 5 dl/g (measured at 25 C in 1 M NaCl), and (c) optionally, at least one cationic coagulant.

2. A process according to claim 1 in which the aqueous slurry comprises clay in a coagulated state and the treatment system comprises adding to the aqueous slurry aluminosilicate nanoparticulate material (a) to reduce the coagulated state of the clay particles to a less coagulated state within the aqueous slurry and then addition of the polymeric flocculant (b) to flocculate the sand and de-coagulate treated clay par-ticles.

3. A process according to claim 1 or claim 2 in which the aqueous slurry comprises a sand to fines ratio of from greater than 1:1 to 2:1.

4. A process according to any preceding claims in which the aqueous slurry has a fines solids content of from 10% to 45% by total weight of aqueous slurry.

5. A process according to any preceding claim in which the aqueous slurry has been derived from an oilsands fluid fines tailings (FFT), thickened fine tailings or a mature fines tailings (MFT).
Date reçue/Received Date 2020-04-06

6. A process according to any preceding claim in which the aqueous slurry compris-es from 10 percent to 70 percent clay particles based on the total weight of solids.

7. A process according to any preceding claim in which the clay particles contained in the aqueous slurry are predominantly kaolinite and illite, additionally comprises smectite and chlorite.

8. A process according to any preceding claim in which the aluminosilicate nano-particulate material has a molar ratio of aluminium to silicon of from 0.8:1 to 2.5:1.

9. A process according to any preceding claim in which the aluminosilicate nano-particulate material has a molar ratio of aluminium to silicon of from 0.9:1 to 2:1.

10. A process according to any preceding claim in which the aluminosilicate nano-.. particulate material consists predominantly of particles of size below 50 nm, prefera-bly below 20 nm.

11. A process according to any preceding claim in which the aluminosilicate nano-particulate material consists predominantly of sodalite aluminosilicate structures.

12. A process according to any preceding claim in which the polymeric flocculent (b) is a polymer formed from repeating units derived from at least one ethylenically un-saturated monomer bearing an anionic group and optionally at least one ethylenically unsaturated non-ionic monomer.

13. A process according to any preceding claim in which the polymeric flocculent (b) is a water-soluble polymer derived from ethylenically unsaturated monomers selected from the group consisting of homopolymers of an ethylenically unsaturated acid monomers (or salts thereof); and copolymers formed from a monomer mixture com-prising of (A) one or more ethylenically unsaturated acid monomers (or salts thereof), (B) one or more ethylenically unsaturated non-ionic monomers selected from the group consisting of acrylamide, methacrylamide, hydroxy alkyl acrylate, vinyl acetate, vinyl alcohol, allyl alkyl ether, styrene and C1-8 alkyl acrylates, and optionally (C) one or more other ethylenically unsaturated monomers different from (A) and (B).
Date reçue/Received Date 2020-04-06

14. A process according to claim 13 in which the one or more ethylenically unsatu-rated acid monomers are selected from the group consisting of acrylic acid, meth-acrylic acid, maleic acid, fumaric acid, itaconic acid, 2-acrylamido-2-methyl propane sulphonic acid, vinylsulfonic acid, allyl sulphonic acid, vinylphosphonic acid and 2-5 .. hydroxy ethyl methacrylate phosphate.

15. A process according to claim 13 or claim 14 in which the one or more other eth-ylenically unsaturated monomers (C) are selected from one or more cationic mono-mers, provided that overall anionic equivalent content is greater than the overall cati-10 onic equivalent content and preferably the one or more cationic monomers are in-cluded in the monomer mixture in an amount of up to 10 mol % total cationic mono-mer based on the total molar content of monomers in the monomer mixture.

16. A process according to any preceding claim in which the polymeric flocculent (b) 15 is a copolymer of acrylamide with (meth)acrylic acid (or salt thereof) or a homopoly-mer of (meth)acrylic acid (or salt thereof).

17. A process according to any preceding claim in which the polymeric flocculent (b) exhibits an intrinsic viscosity of at least 6 dl/g.

18. A process according to any preceding claim in which the cationic coagulant (c) is selected from the group consisting of homopolymers of diallyldimethylammonium chloride (DADMAC), copolymers of diallyldimethylammonium chloride (DADMAC) and acrylamide, homopolymers of methyl chloride quaternised dimethyl amino ethyl acrylate (DMAEA-q), copolymers of methyl chloride quaternised dimethyl amino ethyl acrylate (DMAEA-q) and acrylamide, homopolymers of methyl chloride quaternised dimethyl amino ethyl methacrylate (DMEMA-q), copolymers of methyl chloride quaternised dimethyl amino ethyl methacrylate (DMEMA-q) and acrylamide, homo-polymers of acrylamido propyl trimethylammonium chloride (APTAC), copolymers of acrylamido propyl trimethylammonium chloride (APTAC) and acrylamide, homopoly-mers of methacrylamido propyl trimethylammonium chloride (MAPTAC), copolymers of methacrylamido propyl trimethylammonium chloride (MAPTAC) and acrylamide, partially or fully hydrolysed polyvinyl formamides containing repeating vinyl amine Date reçue/Received Date 2020-04-06 units; polyethyleneimines, polymers formed from alkyl amines with formaldehyde and/or epichlorohydrin, and polycyandiamides.

19. A process according to any preceding claim in which the aqueous slurry is formed from a first precursor aqueous slurry in which the sand to fines ratio is below 1:1, and the sand to fines ratio is adjusted to increase the sand to fines ratio by ei-ther, (a) combining the first precursor aqueous slurry with sand; and/or (b) combining the first precursor aqueous slurry with a second precursor aqueous slurry, which second precursor aqueous slurry has a sand to fines ratio of greater than 3:1, suitably greater than 4:1 and especially suitably greater than 5:1, and thereby forming the aqueous slurry, in which the treatment system or components thereof are applied to any one or more of the first precursor aqueous slurry, the sand component, the second precursor aqueous slurry and/or the aqueous slurry.

20. A process according to claim 19 in which the sand in (a) is in the form of a sand stream, preferably the underflow sand stream from a cyclone processing whole tail-ings (WT).

21. A process according to claim 19 or claim 20 in which the first precursor aqueous slurry is selected from the group consisting of mature fines tailings (MFT), fluid fines tailings (FFT), thin fines tailings (TFT), thickened fines tailings (ThFT).

22. A process according to any of claims 1 to 18 in which the aqueous slurry is formed from a second precursor aqueous slurry in which the sand to fines ratio is greater than 3:1, suitably greater than 4:1 and especially suitably greater than 5:1, and the sand to fines ratio is adjusted to decrease the sand to fines ratio by separat-ing sand particles having a particle size greater than a predetermined size limit, pref-erably greater than 100 pm, from the second precursor aqueous slurry thereby, and thereby forming the aqueous slurry, in which the treatment system or components thereof are applied to any one or more of the second precursor aqueous slurry and/or the aqueous slurry.
Date reçue/Received Date 2020-04-06

23. A process according to any of claims 19 to 21 in which the second precursor aqueous slurry is whole tailings (VVT).

24. A process according to claim 22 in which the separation of the sand from the second pre-cursor aqueous slurry is conducted using a cyclone or a screen sufficient to remove the sand particles having a particle size greater than the predetermined size limit.

25. A process according to any preceding claim in which the aqueous slurry of par-ticulate material comprises flowing as slurry of mature fines tailings (MFT) and/or fluid fines tailings (FFT) along a conduit and in which a slurry of sand is combined with the slurry of mature fines tailings and/or fluid fines tailings to provide a combined tailings stream (CbT), wherein the components of the treatment system are applied to (i) the mature fines tailings and/or fluid fines tailings; and/or (ii) the combined tailings stream (CbT), and in which the so treated combined tailings stream is fed to a deposition area.

26. A process according to claim 25 in which the aluminosilicate nanoparticulate ma-terial (a) is either fed into the slurry of MFT and/or FFT, fed into the sand slurry or fed into the combined tailings stream (CbT) and thereafter the polymeric flocculant (b) is added to the so treated combined tailings stream (CbT).

27. A process according to claim 25 or claim 26 in which the so treated combined tailings stream (CbT) is fed into a void or impoundment at the deposition area, in which the void or impoundment has a depth of at least 5 m, preferably at least 20 m, and the deposited solids are allowed to separate from the released supernatant liquid and consolidate.

28. A process according to claim 27 in which a supernatant liquid separated from the so treated slurry forms above the particulate solids deposited in the void or im-poundment and in which the supernatant liquid is continually or periodically removed from the void.
Date reçue/Received Date 2020-04-06

29. A process according to claim 27 or claim 28 in which the so treated combined tailings stream is fed onto a beach surface at the deposition area and form thin layers of newly deposited beach material which dewaters through drainage and evapora-tion.

30. A process according to claim 29 in which the beached surface has an angle of incline of between 0.5 and 10 .

31. A process according to any preceding claim in which the aqueous slurry of par-ticulate material is first treated by the addition of the aluminosilicate nanoparticulate material (a) and then subjecting the so treated aqueous slurry to a mixing stage fol-lowed by addition of the polymeric flocculant (b).

32. A process according to any preceding claim in which the aqueous slurry of par-ticulate material is treated by the addition of the treatment system and then subject-ing the so treated aqueous slurry to a mixing stage.

33. A process according to any preceding claim in which the aqueous slurry of par-ticulate material is subjected to a mixing stage after the addition of each of the alumi-nosilicate nanoparticulate material (a) and the polymeric flocculant (b) of the treat-ment system.

34. A composition formed from an aqueous slurry containing particulate material, which particulate material comprises sand particles and fines particles and contains clay particles, which aqueous suspension has a solids content of from 30 to 70% by weight and a sand to fines ratio of from greater than 1:1 to 3:1, which composition comprises flocculated particulate solids and a treatment system in which the treatment system comprises (a) at least one aluminosilicate nanoparticulate material, in which the molar ratio of aluminium to silicon is from 0.7:1 to 3:1;
(b) at least one polymeric flocculant, which has an intrinsic viscosity of at least 5 dl/g (measured at 25 C in 1 M NaCl), and (c) optionally, at least one cationic coagulant.
Date reçue/Received Date 2020-04-06

35. A composition according to claim 34 incorporating one or more of the features of any of claims 3 to 18.

36. A treatment system for separating solids from an aqueous slurry containing par-ticulate material, which particulate material comprises sand particles and fines parti-cles and contains clay particles, which aqueous slurry has a solids content of from 30 to 70% by weight and a sand fines ratio of greater than 1:1 to 3:1, in which the treatment system comprises (a) at least one aluminosilicate nanoparticulate material, in which the molar ratio of aluminium to silicon is from 0.7:1 to 3:1;
(b) at least one polymeric flocculant, which has an intrinsic viscosity of at least 5 dl/g (measured at 25 C in 1 M NaCl), and (c) optionally, at least one cationic coagulant.

37. A treatment system according to claim 36 incorporating one or more features of any of claims 3 to 18.

38. Use of a treatment system for separating solids from an aqueous slurry contain-ing particulate material, which particulate material comprises sand particles and fines particles and contains clay particles, which aqueous slurry has a solids content of from 30 to 70% by weight and a sand fines ratio of greater than 1:1 to 3:1, in which the treatment system comprises (a) at least one aluminosilicate nanoparticulate material, in which the molar ratio of aluminium to silicon is from 0.7:1 to 3:1;
(b) at least one polymeric flocculant, which has an intrinsic viscosity of at least 5 dl/g (measured at 25 C in 1 M NaCl), and (c) optionally, at least one cationic coagulant.

39. Use according to claim 38 incorporating one or more features of any of claims 3 to 18.
Date reçue/Received Date 2020-04-06