[0001] The present invention relates to a vehicle and methods of enhancing and use of the vehicle in the dewatering of settling ponds, particularly tailings, slurries, soft soils, dredge spoils and the like.

BACKGROUND

[0002] Tailings, also called slimes, leach residue, or slickens, are the waste materials left over after mechanical and chemical processes are used to extract a desirable fraction from a non-desired fraction of a mined ore. Dredge spoils is generally underwater sediment material (e.g., sand, silt and clay material) excavated during dredging activities, such as, e.g., the maintenance of shipping transport routes and port facilities. Typically, both tailings and dredge spoils (collectively hereafter referred to as a "slurries") have a semi-liquid consistency containing particles of solid material (e.g., ground rock, process effluents and/or sediment material) ranging in size from the size of a grain of sand to a few microns, and fluid. In some cases, a slurry further includes process additives to enhance the settling and consolidation of the ground rock and process effluents.

[0003] Typically, mine processing plants, port authorities or other processing facilities dispose of slurries in a disposal facility in the form of a tailings dam, pond or similar impoundment (collectively hereafter referred to as a "settling pond").

[0004] Over the last century, the volumes of slurries being generated from the resources sector has grown dramatically as the demand for minerals and metals has increased and lower and lower grades of ore are being mined. Similarly, increased maritime and general shipping traffic and subsequent port activity has increased the importance and frequency of maintaining shipping transport routes, and thus dredging activity. As such, many techniques are being employed to try and reduce the area required for an effective settling pond and/or to increase the load of existing settling ponds. Generally, all such techniques involve trying to improve the consolidation and dewatering rates of slurries through chemical and/or mechanical means, since the natural dewatering of slurries by consolidation and evaporation can take several years, is unpredictable and leads to variable outcomes.

[0005] Such mechanical means can involve a process whereby at least one vehicle (generally an Archimedes screw propelled vehicle) makes multiple passages across a settling pond to enhance the consolidation and dewatering of the slurry contained therein.

[0006] Whilst the above process has proven to be effective in improving the consolidation and dewatering of slurries, the present inventors have recognised that the process is not optimal and that through further refinements to both the vehicle utilised and its application, the consolidation and dewatering of slurries can be further enhanced.

SUMMARY OF INVENTION

[0007] Embodiments of the present invention provide a vehicle and methods, which may minimize or overcome at least one of the problems or difficulties mentioned above, or which may provide the public with a useful or commercial choice.

[0008] According to a first aspect of the present invention there is provided a method of enhancing a vehicle for or when used for mechanically dewatering a slurry, said method including:

measuring one or more parameters of the slurry;

determining a suitable buoyancy profile for the vehicle based on the one or more parameters measured; and

modifying one or more features of the vehicle based on the buoyancy profile determined so as to provide the vehicle with a desired operating depth, speed and/or traction in the slurry.

[0009] According to a second aspect of the present invention, there is provided a vehicle for mechanically dewatering a slurry, said vehicle including one or more features that have been modified based on a suitable buoyancy profile determined for the vehicle, said buoyancy profile being based on one or more parameters of the slurry that have been measured, wherein said vehicle has been modified to provide a desired operating depth, speed and/or traction in the slurry.

[0010] According to a third aspect of the present invention, there is provided a vehicle for mechanically dewatering a slurry when enhanced by the method of the first aspect.

[0011] Advantageously, the enhanced vehicle and methods of the present invention allow for a more efficient and cost-effective dewatering of slurries. By modifying the vehicle to suit the characteristics of a slurry to be dewatered, the vehicle is configured with a substantially optimal balance of speed, traction and operating depth to enhance the dewatering of the slurry with minimal re-pulping (i.e., re-saturating/re-mixing), the latter being a common problem associated with the use of other untailored mechanical dewatering vehicles. Moreover, the present invention provides a resulting vehicle that is substantially safer to operate than other untailored mechanical dewatering vehicles, which often have mismatched characteristics, such as, e.g., traction with weight, in order for the vehicle to be capable of high speed, at the expense of stability. A person skilled in the art will appreciate that the use of other untailored mechanical dewatering vehicles typically results in an inefficient dewatering operation that, in some case, can be unsafe.

[0012] A person skilled in the art will also appreciate that the vehicle and methods of the present invention while described with respect to the dewatering of slurries in settling ponds, may be applied to any semi-liquid, self-settling mixture capable of being mechanically dewatered and in which transition of the mixture to a solid phase is desired, such as, e.g., the dewatering of construction sites, agricultural sites, environmental sites, land reclamation impoundments, river beds, fine solids or municipal biosludge and the like.

[0013] As used herein, the term "settling pond" refers to any reservoir open to the atmosphere and used to collect slurry-like material. The term encompasses tailings dams, waterlogged marshes, dredge spoil impoundments and the like. The settling pond may include a substrate over which the slurry is deposited.

[0014] As used herein, the term "slurry" and variations such as "slurries" refers to emplaced tailings, slimes, leach residues, slickens, dredge spoils and other like material having slurry-like properties.

[0015] As used herein, the term "slurry discharge point" refers to a location in the settling pond from which slurry is discharged into the settling pond.

[0016] As used herein, the term "drainage collection point" refers to a low point in the settling pond or operational area designated to collect run-off fluid.

[0017] As used herein, the term "vehicle" may encompass any land or amphibious vehicle configured to traverse over slurries and slurry-like mediums. Preferably, a vehicle adapted to provide low ground pressure.

[0018] The vehicle may include a chassis, a cabin, and at least one auger-like cylinder fitted with at least one outwardly extending helical spiral flange (hereafter collectively referred to as a "scroll"). Typically, the vehicle may be propelled by rotation of the scroll. Preferably, the at least one outwardly extending helical spiral flange may be configured to engage with a medium through or over which the vehicle traverses.

[0019] Preferably, the vehicle includes at least two scrolls extending beneath and/or along each longitudinal side of the chassis. Of the at least two scrolls, one scroll may have at least one helical spiral flange that extends clockwise along a length of the scroll, and the other scroll may have at least one helical spiral flange that extends counter-clockwise along a length of the scroll.

[0020] The vehicle is inherently buoyant irrespective of the medium through or over which it traverses, which may at least be partially attributable to the scrolls, which are substantially hollow.

[0021] The vehicle may include one or more engines to counter-rotate the scrolls such that one scroll rotates clockwise and the other scroll rotates counter-clockwise. Advantageously, any lateral movement of the vehicle may be cancelled out by counter-rotation of the scrolls thereby allowing the vehicle to be propelled either forwards or backwards in a direction substantially parallel with the axis of rotation of the scrolls.

[0022] In use, the vehicle facilitates in the mechanical dewatering of slurries through the dewatering and subsequent consolidation of slurry material under the loading weight of the vehicle as it traverses over the surface of the slurry, and the creation of surface drainage channels (i.e., scroll lines) by the passage of the scrolls of the vehicle. Typically, as the slurry material consolidates, fluid is released into the scroll lines and drains away.

[0023] The vehicle may or may not include a vehicle tracking system to assist in tracking of the vehicle in operation. Typically, the vehicle tracking system may include a GPS logger unit or GPS tracker or other hardware/software to assist in tracking of the vehicle, preferably off site tracking.

[0024] As indicated above, the method of enhancing the vehicle for mechanical dewatering includes an initial step of measuring one or more parameters of the slurry to be dewatered in order to determine a buoyancy profile for the vehicle. The one or more parameters may include any parameter suitable for the determining of the buoyancy profile. For example, the parameters may include one or more of initial slurry density (preferably initial settled slurry density), initial slurry depth, initial shear strength, initial slurry viscosity, initial moisture content, initial particle size distribution ("PSD") and initial residue solids content. Preferably, the one or more parameters measured may at least include initial slurry depth, initial moisture content and initial settled slurry density.

[0025] Typically, the one or more parameters are measured from at least one sample taken from the slurry to be dewatered. The one or more parameters may be measured using any suitable means. For example, some parameters may be measured using a hand-held shear vane shear tester together with routine slurry coring to develop a density/shear strength curve.

[0026] Preferably, the parameters are measured from at least two samples taken from the slurry, more preferably from samples taken at different locations within the slurry.

[0027] In preferred embodiments, the measuring of the one or more parameters may be deferred or delayed until the slurry no longer releases excess fluid by consolidation under gravity alone. This is known as reaching "field capacity" or a density at which excess fluid stops being shed by consolidating forces at a rate equal to the vertical permeability of the slurry.

[0028] A person skilled in the art will appreciate that the "field capacity" is variable depending on the properties of the slurry. Typically, however, a slurry is allowed to consolidate for a period of between 24 to 72 hours or longer before said measuring is undertaken. Advantageously, this allows for an accurate measurement of at least the initial settled slurry density.

[0029] Once the measuring is undertaken, the method includes a subsequent step of determining a suitable buoyancy profile for the vehicle based on the one or more parameters measured, preferably at least the initial slurry depth, the initial moisture content and the initial settled slurry density, most preferably at least the initial settled slurry density.

[0030] Any suitable buoyancy profile may be determined to achieve a desired buoyancy of the vehicle in a slurry for efficient dewatering of the slurry.

[0031] For example, it may be desirable that a portion of the vehicle be more or less buoyant in the slurry than other portions of the vehicle.

[0032] Typically, however, the buoyancy profile may be determined to achieve a desired buoyancy of the vehicle as a whole relative to the slurry, preferably along a longitudinal axis of the vehicle.

[0033] Preferably, the buoyancy profile may be determined such that the vehicle achieves a maximal penetration of the scrolls within the slurry.

[0034] In some embodiments, the maximal penetration of the scrolls within the slurry may result in the scrolls engaging with the substrate underlying the slurry, for example.

[0035] In other embodiments, however, the initial slurry depth may exceed a maximal operating depth capability of the vehicle.

[0036] A person skilled in the art will appreciate that whether or not the scrolls of the vehicle engage with the substrate is largely dependent on the initial slurry settled density and the initial slurry depth (i.e., pour depth).

[0037] In scenarios in which an initial slurry depth exceeds the maximal operating depth capability of the vehicle, the vehicle may still be used to dewater the slurry albeit less effectively at least partially due to reduced traction, a reduced operating speed and a reduced consolidating force applied by the vehicle, mainly the reduced consolidating force applied by the vehicle. Typically, the vehicle in such scenarios is able to propel through or over the slurry through a propeller-like action of the scrolls.

[0038] However, in preferred embodiments and as indicated above, the pour depth of the slurry may be controlled or within a range at which the scrolls of the vehicle, when configured for maximal penetration, are able to engage with the substrate underlying the slurry and thereby achieve substantial traction and an efficient or desired operating speed.

[0039] In some embodiments, said determining a suitable buoyancy profile for the vehicle based on the one or more parameters measured may be at least partially undertaken or at least partially assisted with the use of designing and modelling software.

[0040] Once a suitable buoyancy profile for the vehicle has been determined, one or more features of the vehicle may be modified so as to provide the vehicle with a desired operating depth, speed and/or traction in the slurry to be dewatered, preferably whilst maintaining stability. [0041] As hereinbefore mentioned, the desired operating depth is the depth at which the vehicle achieves maximal penetration of the scrolls within the slurry, preferably a depth at which the scrolls are able to engage with the substrate underlying the slurry, slurry depth permitting. Typically, the scrolls of the vehicle of the present invention are able to engage with the substrate underlying the slurry at a depth of up to about 1,200mm.

[0042] Likewise, the desired traction is preferably maximum traction, which, as also hereinbefore mentioned, is at least partially dependent on the maximal penetration of the scrolls within the slurry.

[0043] The desired speed is preferably the maximum operating speed the vehicle is capable of while maintaining dewatering activities (i.e., without re-pulping/re-mixing/re-saturating occurring). A person skilled in the art will appreciate that this is at least partially affected by the properties of the slurry. For example, dewatering of a slurry with a lower density is likely to require the vehicle operating at a lower speed than a slurry with a higher density if re -pulping is to be avoided or at least minimized. Typically, the desired speed may be between about 0.1 m.s ^-1 and about 1 m.s ^-1 . The vehicle has an absolute maximum speed of about 2 m.s ^-1 .

[0044] Typically, the one or more features of the vehicle modified may include any suitable feature that has an effect on the desired operating depth, speed and/or traction.

[0045] For example, the one or more features may include any feature that alters the buoyancy of the vehicle, which in turn may at least partially affect the operating depth, speed, and/or traction. Preferably, the one or more features may include features that are readily altered or adjustable. Advantageously, this may assist in modifying the one or more features to suit another slurry at a later date.

[0046] Altering the mass of the vehicle, for example, may alter the buoyancy of the vehicle. This may be achieved through any suitable means, such as, e.g., the addition or removal of mass from the vehicle (e.g., one or more weights or counterweights, one or more sand bags, etc.).

[0047] In some embodiments, the mass of the vehicle may be altered through the use of a ballast-like tank system. The ballast-like tank system may include one or more tanks located in suitable locations on the vehicle and configured to each hold a volume of material, preferably a fluid, such as, e.g. water or the like, and/or a fine particulate, such as, e.g., sand or the like, to alter the mass and thereby the buoyancy of the vehicle. The volume of material held by each tank may be altered by hand or by one or more pumps operatively associated with the tanks.

[0048] In some embodiments, the mass of the vehicle may be altered by modifying the scrolls of the vehicle. For example, in scenarios where the vehicle needs to be more negatively buoyant, the scrolls of the vehicle may be substituted for smaller less buoyant scrolls. Conversely, in scenarios where the vehicle needs to be more positively buoyant, the scrolls of the vehicle may be substituted for larger more buoyant scrolls.

[0049] The one or more features of the vehicle modified may also include modifications to the scrolls.

[0050] For example, modification to increase or decrease a number of helical spiral flanges that extend along a length of each scroll or a portion thereof. Typically, this modification will be limited to a vehicle including more than one helical spiral flange that extends along a length of each scroll or a portion thereof.

[0051] For example, modification of the pitch and/or height of the helical spiral flange that extends along a length of each scroll or a portion thereof may alter the speed and/or traction of the vehicle.

[0052] In some embodiments, the number and/or the pitch of the helical spiral flange or a portion thereof may be altered to achieve a desired traction and/or desired speed. For example, the number of helical spiral flanges may be increased or reduced to respectively increase or reduce traction. For example, the pitch may be increased to provide reduced traction and greater speed or decreased to provide greater traction and reduced speed.

[0053] Likewise, in some embodiments, the height of the helical spiral flange or a portion thereof may be altered to achieve a desired traction. For example, the height may be increased to provide greater traction and/or greater speed or decreased to provide reduced traction, gross weight and limit achievable speed.

[0054] Like with the determining of the suitable buoyancy profile, in some embodiments, said modifying one or more features of the vehicle may be at least partially undertaken or at least partially assisted with the use of designing and modelling software.

[0055] The method may include a further step of testing the vehicle for static and/or dynamic stability, preferably prior to deploying the vehicle on the slurry to be dewatered. In preferred embodiments, the testing may be at least partially undertaken or at least partially assisted with the use of designing and modelling software.

[0056] The testing may include any suitable tests configured to determine a stability of the vehicle when operating at the desired operating depth, speed and/or traction in the slurry to be dewatered. Preferably, the testing may also test the vehicle at other operating depths, speeds and/or tractions and/or other slurry conditions.

[0057] Based on the testing, the method may include a further subsequent step of re- modifying one or more features of the vehicle based on the buoyancy profile and the testing, preferably to achieve a desired stability. In a preferred embodiment, the re-modifying may include altering the mass of the vehicle and/or the centre of gravity of the vehicle, preferably via the ballast-like tank system, to at least partially enhance the stability of the vehicle while providing the vehicle with the desired operating depth, speed and/or traction in the slurry.

[0058] The method may include a further step of balancing an achievable speed through traction limitation with stability afforded by a centre of gravity of the vehicle as a result of the specific buoyancy profile determined in the slurry (irrespective of slurry depth).

[0059] According to a fourth aspect of the present invention, there is provided a method of enhancing the dewatering of a slurry, said method including the following steps:

(a) providing the vehicle of the second or third aspects;

(b) identifying one or more parameters of the slurry, including an initial slurry density, a target slurry density, an initial shear strength of slurry and/or a target shear strength of slurry;

(c) determining one or more operational parameters, including optimal path, duration and/or frequency of passage of the vehicle over the slurry, based on the parameters of the slurry identified;

(d) traversing the slurry with the vehicle according to the operational parameters determined; and

(e) repeating said traversing of step (d) until at least the target slurry density and/or target shear strength of slurry is reached.

[0060] The method may include one or more features or characteristics of the vehicle and method of enhancement as hereinbefore described. [0061] The method may include one or more features or characteristics of the methods disclosed or described in Canadian Patent Application No. 2 742 041, filed 2 June 2011, and U.S. Patent Application No. 13/782,104 (U.S. Publication No. US 2014/0246385 Al), filed 1 March 2013, the entire contents of both being incorporated herein by reference.

[0062] As indicated, the method in step (b) includes the identifying of one or more parameters of the slurry, including an initial slurry density, a target slurry density, an initial shear strength of slurry and/or a target shear strength of slurry, preferably initial settled slurry density.

[0063] The method may further include identifying any one of the parameters hereinbefore mentioned and/or identifying one or more parameters of the settling pond within which the slurry to be dewatered is contained.

[0064] The method may further include identifying one or more further parameters, such as, e.g., regional climatology and settling pond personnel operation parameters (e.g., shift rosters).

[0065] In preferred embodiments, the method in step (b) may include: identification of one or more parameters of the slurry including initial settled slurry density, target slurry density, initial shear strength of slurry, target shear strength of slurry, initial depth of slurry, target depth of slurry, specific gravity, vertical permeability of the saturated slurry, and variability in slurry initial viscosity; identification of one or more parameters of the settling pond including area of operation, angles of repose, locations of slurry discharge points, locations of drainage collection points and drainage structures; and identification of one or more parameters of the regional climatology including median rainfall, median evaporation and the relationship between pan evaporation and lake evaporation.

[0066] Once the parameters of the slurry have been identified, the method in step (c) includes determining one or more operational parameters, including optimal path, duration and/or frequency of passage of the vehicle over the slurry, based on the parameters of the slurry identified.

[0067] Typically, the operational parameters determined will be optimal parameters likely to result in optimal dewatering of the slurry.

[0068] For example, the optimal path will typically be a path in which drainage of fluid released from the slurry by passage of the vehicle is optimised. The optimal path may be any particular path suitably adapted to create a surface drain to direct fluid released from an elevated or consolidated portion of the slurry to a drainage collection point of the settling pond. In some embodiments, the optimal path may be a path extending substantially between a slurry discharge point and the drainage collection point of the settling pond.

[0069] The optimal path may be adapted in response to vehicle performance and slurry behaviour during dewatering operations to sustain optimal dewatering of the slurry.

[0070] The optimal duration and/or frequency of passage of the vehicle may preferably be any suitable duration and/or frequency that at least sustains dewatering of the slurry while minimising re-pulping.

[0071] In step (d) of the method, the slurry may be traversed with the vehicle typically until at least the settling pond has been entirely traversed, preferably thereby covering the settling pond and the slurry contained therein with scroll lines to assist in drainage of fluid released from the slurry.

[0072] In step (e), said traversing may be repeated until at least the target slurry density and/or target shear strength of slurry is reached. Typically, when repeating said traversing, scroll lines formed in step (d) may be deepened by repeat passages of the vehicle and/or split by repeat passages of the vehicle between previously formed scroll lines.

[0073] In a preferred embodiment, the method may include periodic monitoring of at least the slurry density and/or the shear strength of the slurry.

[0074] Typically, the periodic monitoring may include routine measuring of at least the slurry density and/or shear strength of slurry to identify when the target slurry density and/or target shear strength of slurry is reached.

[0075] Measurements may be made using any suitable means. Preferably, the measurements may be made using a hand-held shear vane shear tester together with routine slurry coring to develop a density/shear strength curve.

[0076] Once sufficient measurements have been made, the shear vane measurements may then be used to infer the slurry density. An advantage of taking routine measurements is that rapid density determinations may be made thus allowing the forecasting of future slurry deposition schedules.

[0077] Any of the features described herein can be combined in any combination with any one or more of the other features described herein within the scope of the invention.

[0078] The reference to any prior art in this specification is not, and should not be taken as an acknowledgement or any form of suggestion that the prior art forms part of the common general knowledge.

BRIEF DESCRIPTION OF DRAWINGS

[0079] Preferred features, embodiments and variations of the invention may be discerned from the following Detailed Description which provides sufficient information for those skilled in the art to perform the invention. The Detailed Description is not to be regarded as limiting the scope of the preceding Summary of Invention in any way. The Detailed Description will make reference to a number of drawings as follows:

[0080] Figure 1 is a photograph showing a representative example of a vehicle used for mechanically dewatering a slurry;

[0081] Figure 2 is a flow chart showing steps in a method of enhancing the vehicle shown in Figure 1 for mechanically dewatering a slurry according to an embodiment of the present invention; and

[0082] Figure 3 is a flow chart showing steps in a method of enhancing the dewatering of a slurry according to an embodiment of the present invention.

DETAILED DESCRIPTION

[0083] Figure 1 shows a vehicle (100) used for the mechanical dewatering of slurries. The vehicle (100) includes a chassis (110), a cabin (120) and two scrolls (130) configured to rotate and propel the vehicle (100). Each scroll (130) has at least one outwardly extending helical spiral flange (132) configured to engage with the medium through or over which the vehicle (100) traverses.

[0084] The two scrolls (130) extend beneath and/or along each longitudinal side of the chassis (110). One scroll (130) has at least one helical spiral flange (132) that extends clockwise along a length of the scroll (130). The other scroll (130) has at least one helical spiral flange (132) that extends counter-clockwise along a length of the scroll (130).

[0085] The vehicle (100) is buoyant, at least partially due to the scrolls (130), which are hollow.

[0086] In use, the scrolls (130) are counter-rotated to propel the vehicle (100). That is, one scroll (130) is rotated clockwise and the other scroll (130) is rotated counter-clockwise. Each scroll (130) is driven by an engine.

[0087] The vehicle (100) facilitates in the mechanical dewatering of slurries through the consolidation of slurry material under the loading weight of the vehicle (100) as it traverses over the surface of the slurry. The vehicle (100) further facilitates in the mechanical dewatering of slurries through the creation of scroll lines (i.e., drainage channels; 150) by the passage of the scrolls (130) of the vehicle (100). As the slurry material consolidates, fluid is released into the scroll lines (150) and drains away.

[0088] A method (200) of enhancing the vehicle (100; only shown in Figure 1) to suit a particular slurry to be dewatered is now described with reference to Figure 2.

[0089] At step 210, one or more parameters of the slurry are measured. Typically, the measuring of the parameters of the slurry is deferred or delayed until excess fluid is no longer being released from the slurry under the consolidating force of gravity alone. Typically, this occurs between 24 to 72 hours after the slurry is poured into a settling pond. Sometimes, this can take up to two weeks depending on the slurry's properties.

[0090] The one or more parameters measured will include any parameter suitable in determining a suitable buoyancy profile for the vehicle (100) at subsequent step 212 of the method (200). Typically, at least the initial settled slurry density and the initial slurry depth are measured. Other parameters that can be measured include: initial shear strength; initial slurry viscosity; initial moisture content; initial particle size distribution ("PSD"); and/or initial residue solids content.

[0091] The parameters can be measured by any suitable means. Typically, the parameters are measured from one or more samples taken from the slurry. Generally, from samples taken from different locations within the slurry.

[0092] At step 212, a suitable buoyancy profile for the vehicle (100) is determined based on the one or more parameters measured at step 210.

[0093] Any suitable buoyancy profile is determined to achieve a desired buoyancy of the vehicle (100) in the slurry for the efficient mechanical dewatering of the slurry.

[0094] The buoyancy profile is determined for the vehicle (100) as a whole, and is determined along a longitudinal axis of the vehicle (100).

[0095] The buoyancy profile is determined such that the vehicle (100) achieves a maximal penetration of the scrolls (130; only shown in Figure 1) within the slurry.

[0096] In some scenarios, the initial slurry depth, measured at step 210 can exceed a maximal operation depth capability of the vehicle (100) of 1,200mm. In such scenarios, the vehicle (100) can still be used to dewater the slurry albeit less effectively at least partially due to reduced traction, a reduced operating speed and a reduced consolidating force applied by the vehicle (100), mainly the reduced consolidating force applied by the vehicle (100). The vehicle (100) is, however, still able to propel through the slurry by a propeller- like action of the rotating scrolls (130).

[0097] In other preferred scenarios, the maximal penetration of the scrolls (130) will result in the scrolls (130) engaging with a substrate underlying the slurry and thereby achieving at least substantial traction and an efficient or desired operating speed.

[0098] Generally, in most scenarios, the slurry depth is controlled such that the maximal penetration of the scrolls (130) typically results in the scrolls (130) engaging with the substrate underlying the slurry.

[0099] At step 214, one or more features of the vehicle (100) are modified based on the buoyancy profile determined so as to provide the vehicle (100) with a desired operating depth, speed and/or traction in the slurry to be dewatered.

[00100] The desired operating depth is the depth at which the scrolls (130) of the vehicle (100) achieve maximum penetration of the slurry, and preferably engage with the substrate underlying the slurry, slurry depth permitting.

[00101] The desired speed is a maximum speed the vehicle is capable of while maintaining dewatering activities (i.e., without repulping). [00102] The desired traction is maximum traction, which as mentioned above, is at least partially dependent on the depth of penetration of the scrolls (130) in the slurry.

[00103] The features of the vehicle (100) modified include any suitable feature that alters the buoyancy of the vehicle (100), and, in turn, has at least a partial effect on the operating depth, speed, and/or traction of the vehicle (100) in the slurry.

[00104] The features include features that alter the mass of the vehicle (100) and therefore the buoyancy of the vehicle (100).

[00105] The features can include weights that can be added or removed from the vehicle (100).

[00106] In some embodiments, the vehicle (100) can be fitted with a ballast-like tank system configured to allow the mass of the vehicle (100) to be altered and thereby the buoyancy of the vehicle (100) to be altered. The ballast- like tank system will include tanks located in suitable locations on the vehicle (100) and configured to hold a volume of material (e.g., a fluid such as water or the like, and/or a fine particulate such as sand or the like). The volume of material held by each tank can be altered by either hand or pump.

[00107] The mass and buoyancy of the vehicle (100) can also be modified by altering the size of the scrolls (130) fitted to the vehicle (100). In scenarios in which the vehicle (100) needs to be more negatively buoyant, the scrolls (130) fitted to the vehicle (100) can be substituted for smaller less buoyant scrolls (130). Conversely, in other scenarios in which the vehicle (100) needs to be more positively buoyant, the scrolls (130) fitted to the vehicle (100) can be substituted for larger more buoyant scrolls (130).

[00108] Other features of the vehicle (100) that can be modified to achieve a desired speed and/or traction include the pitch and height of the helical spiral flange (132; shown only in Figure 1) that extends along the length of each scroll (130) and/or the number of helical spiral flanges (132; shown only in Figure 1) that extend along the length of each scroll (130).

[00109] The pitch of the helical spiral flange (132) can be increased to provide reduced traction and therefore greater speed or decreased to provide greater traction and therefore reduced speed.

[00110] Likewise, the height of the helical spiral flange (132) can be increased to provide greater traction and therefore greater speed or decreased to provide reduced traction, gross weight and/or to limit achievable speed.

[00111] The number of helical spiral flanges (132) can be increased or reduced to respectively provide greater traction and therefore greater speed or decreased to provide reduced traction, gross weight and/or to limit achievable speed.

[00112] At step 216, the vehicle (100) is tested for static and/or dynamic stability. The testing includes any suitable tests configured to determine a stability of the vehicle (100) when operating at the desired operating depth, speed, and/or traction in the slurry to be dewatered. The testing can also test the vehicle (100) under other conditions.

[00113] If the vehicle (100) is determined to be stable, dewatering of the slurry using the vehicle (100) can commence.

[00114] If, however, the vehicle (100) is determined to be unstable, one or more features of the vehicle (100) as hereinbefore described at step 214 can be re-modified at step 218 to at least partially enhance the stability of the vehicle (100) while providing the vehicle (100) with the desired operating depth, speed and/or traction in the slurry.

[00115] At step 219, the vehicle (100) is re-tested for static and/or dynamic stability as hereinbefore described with respect to step 216.

[00116] Steps 218 and 219 are repeated until the vehicle (100) is determined to be stable, at which point dewatering of the slurry using the vehicle (100) can commence.

[00117] A method (300) of enhancing the dewatering of a slurry is now described with reference to Figure 3.

[00118] At step 310, a vehicle (100; only shown in Figure 1) is provided that has been enhanced to suit the slurry according to method (200), described above.

[00119] At step 312, one or more parameters of the slurry to be dewatered are identified.

[00120] As with step 210 described above, the identification of the parameters of the slurry is typically deferred or delayed until excess fluid is no longer being released from the slurry under the consolidating force of gravity alone. Typically, this occurs between 24 to 72 hours after the slurry is poured into a settling pond. Sometimes, this can take up to two weeks depending on the slurry's properties.

[00121] The one or more parameters identified include an initial slurry density, a target slurry density, an initial shear strength of slurry and a target shear strength of slurry. Other parameters of the slurry that can be identified include: specific gravity, vertical permeability of the saturated slurry, and variability in slurry initial viscosity.

[00122] The step can further include: identification of one or more parameters of the settling pond including area of operation, angles of repose, locations of slurry discharge points, locations of drainage collection points and drainage structures; and identification of one or more parameters of the regional climatology including median rainfall, median evaporation and the relationship between pan evaporation and lake evaporation.

[00123] The parameters can be identified by any suitable means. Typically, for slurry parameters, the parameters are measured from one or more samples taken from the slurry. Generally, from samples taken from different locations within the slurry.

[00124] At step 314, one or more operational parameters are determined based on the parameters determined in step 312.

[00125] The operational parameters determined include an optimal path, duration and frequency of passage of the vehicle (100) provided in step 310. Generally, the operational parameters determined are optimal parameters likely to result in optimal dewatering of the slurry.

[00126] The optimal path is any particular path across the slurry that will create a surface drain to direct fluid released from an elevated or consolidated portion of the slurry to a drainage collection point of a settling pond within which the slurry is contained. Typically, the optimal path is adapted or modified routinely in response to the vehicle's (100) performance and the slurry's behaviour during dewatering operations in order to ensure sustained optimal dewatering of the slurry.

[00127] The optimal duration and/or frequency of passage of the vehicle (100) is any suitable duration or frequency that at least sustains dewatering of the slurry while minimizing re-pulping.

[00128] At step 316, the vehicle (100) traverses the slurry according to the operational parameters determined at step 314.

[00129] Typically, the slurry is entirely traversed by the vehicle (100) thereby covering the settling pond with scroll lines (150; only shown in Figure 1) to assist in drainage of fluid released from the slurry.

[00130] At step 318, the one or more parameters of the slurry are measured and step 316 is repeated until at least the target slurry density and/or the target shear strength of slurry is reached.

[00131] Typically, at least the slurry density and/or the shear strength of slurry are periodically monitored through routine measurements to identify when the target slurry density and/or the target shear strength of slurry is reached.

[00132] Generally, the routine measurements are made using a hand-held shear vane tester together with routine slurry coring.

[00133] When step 316 is repeated, the vehicle (100) can traverse along the previously formed scroll lines (150) thereby deepening them through repeat passages and/or split the previously formed scroll lines (150) by passing between them.

[00134] In the present specification and claims (if any), the word "comprising" and its derivatives including "comprises " and "comprise " include each of the stated integers but does not exclude the inclusion of one or more further integers.

[00135] Reference throughout this specification to "one embodiment" or "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the present invention. Thus, the appearance of the phrases "in one embodiment" or "in an embodiment" in various places throughout this specification are not necessarily all referring to the same embodiment. Furthermore, the particular features, structures, or characteristics may be combined in any suitable manner in one or more combinations.

[00136] In compliance with the statute, the invention has been described in language more or less specific to structural or methodical features. It is to be understood that the invention is not limited to specific features shown or described since the means herein described comprises preferred forms of putting the invention into effect. The invention is, therefore, claimed in any of its forms or modifications within the proper scope of the appended claims (if any) appropriately interpreted by those skilled in the art.