ENHANCED MECHANICAL DEWATERING OF A SLURRY

Abstract

The present disclosure relates to methods and a vehicle for enhancing the mechanical dewatering of a slurry. In one aspect, the disclosure concerns a method for enhanced dewatering of a settling pond with a mechanical dewatering vehicle including: measuring one or more properties of a slurry to be deposited in the settling pond; determining a buoyancy profile for the vehicle, based on the one or more properties measured and one or more properties of the vehicle, such that the vehicle is neutrally buoyant in the slurry when deposited in the settling pond; and determining an optimal slurry depth for the slurry to be deposited in the settling pond such that the vehicle is able to maintain substantially shear-free traction as the vehicle traverses the slurry.

Claims

1-21. (canceled)

22. A system for enhanced dewatering of a settling pond with a mechanical dewatering vehicle, said system comprising: an external processing device; and at least one measuring device for measuring properties of a slurry to be deposited in the settling pond, wherein the external processing device comprises at least one processor and a memory and is programmed to: determine a buoyancy profile for the vehicle, based on the one or more properties measured and one or more properties of the vehicle, such that the vehicle is neutrally buoyant in the slurry when deposited in the settling pond; and determine an optimal slurry depth for the slurry to be deposited in the settling pond such that the vehicle is able to maintain substantially shear-free traction as the vehicle traverses the slurry.

23. The system of claim 22, wherein the mechanical dewatering vehicle comprises a vehicle configured to traverse over slurries and slurry-like mediums and provide low ground pressure.

24. The system of claim 23, wherein the mechanical dewatering vehicle is an Archimedes Screw Tractor comprising a chassis and at least two scrolls fitted to the chassis, each scroll having at least one outwardly extending helical spiral flange, said vehicle configured to be propelled by rotation of the scrolls such that the flange on each scroll engages with the slurry through or over which the vehicle traverses.

25. The system of claim 22, wherein the properties measured by the at least one measuring device comprise any one of solids density, liquor density, solids flow rate, liquor flow rate, slurry flow rate, slurry density, and slurry shear strength.

26. The system of claim 22, wherein the properties measured comprise any one of initial settled slurry density, initial shear strength, initial slurry viscosity, initial moisture content, initial particle size distribution and initial residue solids content.

27. The system of claim 22, wherein the vehicle is neutrally buoyant when a buoyant force acting on the vehicle substantially equals forces that would otherwise cause the vehicle to sink or rise in the slurry in the settling pond.

28. The system of claim 22, wherein the substantially shear-free traction comprises traction along a base layer of the settling pond without re-pulping, re-mixing or re-saturation of the base layer.

29. The system of claim 26, wherein the one or more properties of the vehicle considered when determining said buoyancy profile comprise any one of the mass of the vehicle, the volume of the vehicle, a slurry engaging surface area of the vehicle, the dimensions of the scrolls of the vehicle and the volume of the scrolls of the vehicle.

30. The system of claim 29, wherein the one or more of the properties of the vehicle correspond to one or more features of the vehicle capable of being modified so as to enable the vehicle to conform with, or meet, the buoyancy profile determined.

31. The system of claim 30, wherein the one or more features capable of being modified further provide the vehicle with a desired operating speed and traction.

32. The system of claim 30, wherein the one or more features comprise the addition or removal of a mass from the vehicle.

33. The system of claim 30, wherein the one or more features comprise a ballast system configured to adjustably hold a volume of material to alter the mass of the vehicle and thereby the buoyancy of the vehicle.

34. The system of claim 30, wherein the one or more features comprise substituting the scrolls of the vehicle to alter the buoyancy of the vehicle.

35. The system of claim 30, wherein the one or more features comprise modifications to increase or decrease any one of the number, the shape and the pitch of the flange or portions thereof that extend along a length of each said scroll of the vehicle to alter the speed and/or traction of the vehicle and the weight of each scrolls and thus the buoyancy of the vehicle.

36. The system of claim 22, further comprising periodically re-measuring the one or more properties of the slurry to at least monitor when a target slurry density and/or shear strength is achieved or reached.

37. A method of enhanced dewatering of a settling pond with a mechanical dewatering vehicle, said method comprising: measuring one or more properties of a slurry to be deposited in the settling pond; determining a buoyancy profile for the vehicle, based on the one or more properties measured and one or more properties of the vehicle, such that the vehicle is neutrally buoyant in the slurry when deposited in the settling pond; and determining an optimal slurry depth for the slurry to be deposited in the settling pond such that the vehicle is able to maintain substantially shear-free traction as the vehicle traverses the slurry.

38. The method of claim 37, wherein the mechanical dewatering vehicle is an Archimedes Screw Tractor comprising a chassis and at least two scrolls fitted to the chassis, each scroll having at least one outwardly extending helical spiral flange, said vehicle configured to be propelled by rotation of the scrolls such that the flange on each scroll engages with the slurry through or over which the vehicle traverses.

39. The method of claim 37, further comprising periodically re-measuring the one or more properties of the slurry to at least monitory the dewatering of the settling pond.

40. A method of modifying a mechanical dewatering vehicle for enhanced dewatering of a slurry, said method comprising: measuring one or more properties of the slurry; determining a buoyancy profile for the vehicle, based on the one or more properties measured and one or more properties of the vehicle, such that the vehicle is neutrally buoyant in the slurry; and modifying the vehicle, based on the buoyancy profile determined, such that the vehicle is able to maintain substantially shear-free traction as the vehicle traverses the slurry.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0076] Preferred features, embodiments and variations of the disclosure may be discerned from the following Detailed Description which provides sufficient information for those skilled in the art to perform the disclosure. The Detailed Description is not to be regarded as limiting the scope of the preceding Summary of Disclosure in any way. The Detailed Description will make reference to a number of drawings as follows:

[0077] FIG. 1 is a line drawing of a mechanical dewatering vehicle;

[0078] FIG. 2 is an illustration of a system for enhanced dewatering of a settling pond according to an embodiment of the present disclosure;

[0079] FIG. 3 is a flowchart showing steps in a method for enhanced dewatering of a settling pond according to an embodiment of the present disclosure; and

[0080] FIG. 4 is a flowchart showing steps in a method of modifying a mechanical dewatering vehicle for enhanced dewatering of a settling pond according to an embodiment of the present disclosure.

DETAILED DESCRIPTION

[0081] FIG. 1 shows an Archimedes Screw Tractor vehicle (100) used for the mechanical dewatering of slurries. FIG. 2 shows a system (200) for enhanced dewatering of a settling pond. Lastly, FIGS. 3 and 4 respective show a method (300) for enhanced dewatering of a settling pond and a method (400) of modifying a vehicle (100) for enhanced dewatering of a settling pond.

[0082] Referring to FIG. 1, 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.

[0083] 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).

[0084] The vehicle (100) is buoyant at least partially due to the scrolls (130), which are hollow.

[0085] 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.

[0086] The vehicle (100) facilitates in the mechanical dewatering of slurries through consolidation of the slurry material under the loading weight of the vehicle (100) as it traverses over, or through, the slurry. The vehicle (100) further facilitates in the mechanical dewatering of slurries through the formation of scroll lines (i.e., drainage channels; 150) by passage of the scrolls (130) of the vehicle (100). As the slurry material is consolidated, fluid is released into the scroll lines (150) and drains away.

[0087] Referring to FIG. 2, the system (200) includes: an external processing device (210); and a measuring device (not shown) for measuring properties of a slurry sample (220) obtained from a slurry (230) to be deposited in a settling pond. The external processing device (210) is programmed to determine a buoyancy profile the vehicle (100A) based on the one or more properties measured and the properties of the vehicle (100A), such that the vehicle (100B) is neutrally buoyant in the slurry (230) when deposited in the settling pond. The external processing device (210) is further programmed to determine an optimal slurry depth (shown as Δh) for the slurry (230) to be deposited in the settling pond such that the vehicle (100B) is able to maintain substantially shear-free traction along a base layer (240) of the settling pond.

[0088] The measuring includes measuring properties from at least one sample (220) taken from the slurry (230) before it is deposited in the settling pond. The measuring is performed after the sample (220) has reached “settled density” or a density at which excess fluid is no longer being shed by consolidating forces at a rate equal to the vertical permeability of the slurry (230). The properties measured include slurry density and shear strength or properties from which slurry density and/or shear strength can be derived.

[0089] The measuring includes using a measuring device, such as, e.g., a hand-held shear vane shear tester, together with a slurry coring device to develop a density/shear strength curve from which at least slurry density can be inferred, once a suitable number of measurements have been obtained.

[0090] Once the measuring has been undertaken, operations personnel (250) onsite input the properties into the device (210) to determine the buoyancy profile for the vehicle (100A) to be neutrally buoyant within the slurry (230), when deposited in the settling pond.

[0091] A buoyance profile is determined at which the average density of the vehicle (100A) is substantially equal to the density of the slurry (230) into which it is, or will be, at least partially immersed.

[0092] Neutral buoyancy is achieved when a buoyant force acting on the vehicle (100B) balances out forces that would otherwise cause the vehicle (100B) to sink or rise in the slurry (230).

[0093] Based on the buoyancy profile determined, the device further outputs modifications to be made to the vehicle (100A) so as to enable the vehicle (100A) to conform with, or meet, the neutral buoyancy profile determined and/or provide an optimal operating speed to maintain substantially shear-free traction.

[0094] The one or more features include any feature that has an effect on the weight, density and/or buoyancy of the vehicle (100A). For example, the features may include the addition or removal of a mass from the vehicle (100A).

[0095] Conversely, the features may include the use of a ballast-like system provided on the vehicle (100A). The system may include one or more tanks located on the vehicle (100A) and configured to hold a volume of material to alter the mass and thereby the buoyancy of the vehicle (100A).

[0096] Generally, the one or more features include substituting the scrolls (130) of the vehicle (100A) to alter the buoyancy of the vehicle (100A). For example, in scenarios in which the vehicle (100A) needs to be less buoyant, the vehicle (100A) can be fitted with smaller scrolls (130) having a smaller hollow internal volume. Conversely, in scenarios in which the vehicle (100A) needs to be more buoyant, the vehicle (100A) can be fitted with larger scrolls (130) having a larger hollow internal volume.

[0097] The one or more features of the vehicle (100A) may further include modifiable features to provide the vehicle (100A) with an optimal operating speed and/or traction, preferably while maintaining vehicle stability.

[0098] The device (210) is further programmed to determine an optimal slurry depth (Δh) for the slurry (230) to be deposited in the settling pond such that the vehicle (100B) is able to maintain substantially shear-free traction along the base layer (240) of the settling pond at an optimal speed determined by the device (210).

[0099] The optimal slurry depth (Δh) is the depth at which the scrolls (130B) of the vehicle (100B) maintain substantially shear-free traction with the base layer (240) while being neutrally buoyant within the deposited slurry (230). The optimal slurry depth (Δh) coincides with the depth at which the helical flanges (132) of the scrolls (130B) of the vehicle (100B) are able to maintain engagement with the base layer (240) of the settling pond but not a depth at which a remainder of the scrolls (130B) engage with the base layer (240).

[0100] Operations personnel (250) onsite will monitor the slurry depth in the settling pond as the deposited slurry (230) dewaters, and will deposit further slurry (230) as needed to maintain the optimal slurry depth (Δh).

[0101] The external processing device (210) can include a computer, a tablet, a smart phone, a smart watch or a PDA, for example. Generally, the device (210) includes at least one display and one or more keys, buttons or switches for the operations personnel (250) to input the slurry properties measured.

[0102] The method (300) of enhanced dewatering of a settling pond with the vehicle (100) as shown in FIG. 2 is now described in detail with reference to FIG. 3.

[0103] At step 310, the operations personnel (250) measure one or more properties of the slurry sample (220) to determine, or derive, a measurement of at least slurry density and slurry shear strength prior to the slurry (230) being deposited in the settling pond.

[0104] The operations personnel (250) inputs the measurement(s) into the external processing device (210).

[0105] The operations personnel (250) may further input into the external processing device (210) one or more parameters of the settling pond to receive the slurry (230) and/or properties of the vehicle (100A).

[0106] At step 320, the device (210) determines a buoyancy profile for the vehicle (100) to be neutrally buoyant in the slurry (230) when deposited in the settling pond.

[0107] At this stage, the method (300) can include one or more further steps as will be described later with reference to the method (400) for modifying the vehicle (100) for enhanced dewatering of the settling pond. The modifications are made so that the vehicle (100) at least conforms with the neutral buoyancy profile determined at step 320.

[0108] At step 330, the device (210) determines an optimal slurry depth (Δh) for the slurry (230) to be deposited in the settling pond and for the vehicle (100) to maintain substantially shear-free traction along the base layer (240) of the settling pond.

[0109] As indicated above, the optimal slurry depth (Δh) coincides with the depth at which the helical flanges (132) of the scrolls (130B) of the vehicle (100B) are able to maintain engagement with the base layer (240) of the settling pond but not a depth at which a remainder of the scrolls (130B) engage with the base layer (240). This is to prevent re-pulping/re-mixing/re-saturation of the base layer (240) of the settling pond, which would otherwise slow the dewatering process.

[0110] The method (400) of modifying a vehicle (100) for enhanced dewatering of a settling pond with the vehicle (100) as shown in FIG. 2 is now described in detail with reference to FIG. 4.

[0111] At step 410, the operations personnel (250) measure one or more properties of a slurry sample (220) to determine, or derive, a measurement of at least slurry density and slurry shear strength, prior to the slurry (230) being deposited in the settling pond.

[0112] The operations personnel (250) inputs the measurement(s) into the external processing device (210).

[0113] The operations personnel (250) may further input into the external processing device (210) one or more parameters of the settling pond to receive the slurry (230) and/or the properties of the vehicle (100) to be modified.

[0114] At step 420, the device (210) determines a buoyancy profile for the vehicle (100) to be neutrally buoyant in the slurry (230) when deposited in the settling pond.

[0115] At this stage, the device (210) may further suggest modifications to alter the buoyancy of the vehicle (100) so that it conforms with the neutral buoyancy profile determined. The device (210) may further suggest modification to alter the operating speed and/or traction of the vehicle (100).

[0116] At step 430, modifications are made to the vehicle (100) to alter at least the buoyancy of the vehicle (100) to conform with the neutral buoyance profile determined at step 420.

[0117] The modifications may include substituting the scrolls (130) of the vehicle (100).

[0118] For example, in scenarios in which the vehicle (100) needs to be less buoyant, the vehicle (100) can be fitted with smaller scrolls (130) having a smaller hollow internal volume.

[0119] Conversely, in scenarios in which the vehicle (100A) needs to be more buoyant, the vehicle (100A) can be fitted with larger scrolls (130) having a larger hollow internal volume.

[0120] The modifications may further include increasing or decreasing the number, shape and/or pitch of the helical spiral flange (132) or portions thereof that extend along a length of each scroll (130) to alter the weight of each scroll (130) and thus the buoyancy of the vehicle (100) and/or alter the traction and/or operating speed of the vehicle (100).

[0121] 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.

[0122] 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 disclosure. 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.

[0123] In compliance with the statute, the disclosure has been described in language more or less specific to structural or methodical features. It is to be understood that the disclosure is not limited to specific features shown or described since the means herein described comprises preferred forms of putting the disclosure into effect. The disclosure 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.