DEWATERING SCREEN

Abstract

A dewatering screen includes a frame upon which is mounted a deck having a plurality of apertures therein, the frame being mounted on a base and being provided with vibration generator for imparting vibration to the deck. A delivery means delivers wet particulate material to be dewatered onto the deck, and there is at least one dividing wall extending across a portion of the deck, the dividing wall(s) separating the deck into a material dewatering region and one or more water drainage regions. The delivery means delivers wet particulate material to be dewatered onto the material dewatering region.

Claims

1. A dewatering screen comprising: a frame configured for the mounting at a base; a deck mounted upon said frame, said deck having a plurality of apertures therein; a vibration generator for imparting vibration to said deck; and at least one dividing wall extending across a portion of said deck, said at least one dividing wall partitioning said deck into a material dewatering region and one or more water drainage regions; wherein said material dewatering region is configured to receive wet particulate material from a delivery means so that the wet particulate material can be dewatered at said deck.

2. The dewatering screen of claim 1, wherein the width of said material dewatering region is greater than or equal to the total width of said one or more water drainage regions.

3. The dewatering screen of claim 1, wherein said at least one dividing wall extends from an upstream end of said deck towards a downstream end of said deck.

4. The dewatering screen of claim 3, further comprising side walls on either side of said deck, and a rear wall extending between said side walls at said upstream end of said deck, said at least one dividing wall extending from said rear wall of said deck towards said downstream end of said deck.

5. The dewatering screen of claim 4, wherein said at least one dividing wall extends substantially parallel to said side walls.

6. The dewatering screen of claim 4, wherein said at least one dividing wall has a height less than or equal to the height of said side walls.

7. The dewatering screen of claim 4, wherein said at least one dividing wall comprises first and second dividing walls located on either side of said material dewatering region, a respective one of said water drainage regions being provided between each of said first and second dividing walls and a respective side wall of said dewatering screen.

8. The dewatering screen of claim 7, wherein the sum of the widths of said water drainage regions is less than the width of said material dewatering region of said deck.

9. The dewatering screen of claim 8, wherein the width of said material dewatering region is at least twice that of the sum of the widths of said water drainage regions.

10. The dewatering screen of claim 1, wherein said at least one dividing wall has a length of between one third and three quarters of the length of said deck.

11. The dewatering screen of claim 1, wherein said openings in said one or more water drainage regions are greater in area than said openings in said material dewatering region of said deck.

12. The dewatering screen of claim 1, further comprising a weir at a downstream end of said deck.

13. The dewatering screen of claim 12, wherein the height of said at least one dividing wall is greater than the height of said weir.

14. The dewatering screen of claim 1, wherein said deck is arranged substantially horizontally, and said vibration generator is adapted to convey particulate material towards a downstream end of said deck.

15. The dewatering screen of claim 1, further comprising a sump beneath said deck for receiving water and undersize material passing through said openings in said deck.

16. The dewatering screen of claim 15, wherein water and undersize material collected in said sump is pumped to at least one hydrocyclone, at least a portion of an underflow of the at least one hydrocyclone being delivered onto said material dewatering region of said deck.

17. The dewatering screen of claim 1, wherein drainage apertures, slots or channels are provided in at least a portion of said at least one dividing wall to provide an alternative route for water to pass from said material dewatering region into said one or more water drainage regions and/or into a sump located beneath said deck.

18. The dewatering screen of claim 1, wherein the height of said at least one dividing wall varies along its length, the height being greatest at its upstream end and least at its downstream end.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0017] A dewatering screen in accordance with an embodiment of the present invention will now be described, by way of example only, with reference to the accompanying drawings, in which:

[0018] FIG. 1 is a perspective view of a dewatering screen in accordance with an embodiment of the present invention;

[0019] FIG. 2 is a perspective view of the dewatering screen of FIG. 1 with the motor bridge removed for clarity;

[0020] FIG. 3 is a sectional side view of the dewatering screen of FIG. 1 on line A-A of FIG. 4; and

[0021] FIG. 4 is a plan view of the dewatering screen of FIG. 1.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0022] A dewatering screen in accordance with an embodiment of the present invention is illustrated in the drawings. The dewatering screen comprises a deck 2 having a plurality of small openings 4 therein through which water and undersize material (for example fine particles and contaminants) can pass.

[0023] The deck 2 is mounted on a support frame comprises spaced apart side plates 6,8 and interconnecting bridging members (extending below the deck and therefore hidden in the drawings). The support frame may be mounted on a base frame (not shown) via resilient mountings to allow the support frame to move with respect to the base frame. The support frame may be suspended from the base frame via suitable resilient mounts.

[0024] A vibration generator is mounted between the side plates 6,8 of the support frame, extending transverse to the deck 2 of the dewatering screen. The vibration generator may comprise a pair of eccentrically loaded rotors mounted in a motor bridge extending between the side plates 6,8 for rotation about substantially parallel rotational axes extending transverse to the deck 2. A driver or drive means, such as an electric or hydraulic motor (not shown), is typically provided for rotatably driving the rotors. While the rotors are shown in drawings as being mounted above the deck 2, it is envisaged, that the rotors may be mounted beneath the deck 2.

[0025] Rotation of the rotors of the vibration generator imparts a vibratory motion to the deck 2 and to the material carried thereon. Such vibratory motion causes the material placed on the deck to be agitated, preventing blocking of the openings 4 in the deck 2, and causes material on the deck 2 to be conveyed towards a downstream end of the screen.

[0026] The deck 2 may be formed from a plurality of polyurethane mats arranged in a common plane. Side walls 12,14 are provided on either side of the deck 2 adjacent the side plates 6,8 of the frame. A rear wall 16 extend between the side walls 12,14 at an upstream end of the deck 2. A weir 18 may be provided at the downstream end of the deck 2, over which oversize material (e.g. dewatered sand) is arranged to pass to be received within a collection hopper and/or onto a stockpiling conveyor (not shown).

[0027] A sump (not shown) may be provided beneath the deck 2 for collecting water and undersize material that passes through the openings in the deck.

[0028] In the embodiment illustrated in the drawings, a pair of dividing walls 20,22 extend from the rear wall 16 of the deck 2, extending parallel to and spaced from the side walls 12,14 of the deck 2, the dividing walls 20,22 dividing or partitioning the surface of the deck 2 into a central material dewatering region D, upon which material to be dewatered is delivered, and a pair of water drainage regions W1,W2 on either side of the material dewatering region D. The dividing walls 20,22 have a length less than that of the side walls 12,14 of the deck 2, such that gaps remain between the ends of the dividing walls 20,22 and the downstream end of the deck 2. The dividing walls 20,22 may have a length between one third and three quarters of the length of the deck 2. The height of the dividing walls 20,22 may be equal to or slightly less than that of the side walls 12,14 of the deck 2.

[0029] In one embodiment it is envisaged that the dividing walls may have a maximum height at the rear wall 16 of the deck 2 and a reduced height at the downstream ends of the dividing walls, the height of the walls reducing gradually or in steps along their length. This may allow water to weir over the dividing walls from the material dewatering region D into the water drainage regions W1,W2.

[0030] At least a portion of each dividing wall may incorporate water drainage apertures, slots or channels to allow water to drain through the dividing walls from the material dewatering region D into the water drainage regions W1,W2 and/or directly into the sump beneath the deck. The dividing walls may be at least partially hollow to allow water to draining through the walls, from one side to the other or through the bottom of the walls, via suitable apertures in the portions of the deck to which the dividing walls are attached.

[0031] In use, wet particulate material, such as washed sand, to be dewatered is delivered onto the central material dewatering region D of the deck 2 adjacent the upstream end of the deck 2, the material moving towards the downstream end of the deck 2 as the deck is vibrated by the vibration generator. Undersize material and water passes through the openings 4 in the deck 2 while the oversize material, with a reduced water content, passes over the weir 18 at the downstream end of the deck 2. The particulate material tends to form a gradient against the weir 18 at the downstream end of the deck 2.

[0032] As the water and particulate material reaches a downstream end of the dividing walls 20,22, the water, with some particulate material, tends to flow around the end of each dividing wall 20,22 and into the water drainage regions W1,W2 on either side of the material dewatering region, and proceeds towards the upstream end of the deck. This water, with a much lower particulate concentration than that on the remainder of the deck 2, can flow more easily through the openings 4 in the water drainage regions W1,W2 of the deck 2. The openings 4 in the water drainage regions W1,W2 of the deck 2 may be greater in area that those in the material dewatering region D of the deck 2, allowing for an even greater flow rate of water through the deck 2 in the water drainage regions W1,W2.

[0033] Water may also drain in the water drainage regions W1,W2 and/or directly into the sump through drainage apertures, slots or channels in the dividing walls, where provided, providing an alternative route for the water to reach the sump beneath the deck.

[0034] As the flow rate of particulate material and water increases, excess water continues to preferentially flow around the downstream ends of the dividing walls 20,22, and possibly also over the top of the dividing walls 20,22, and into the water drainage regions W1,W2 and readily passes through the deck 2 to drain into the sump therebeneath, while the substantially dewatered particulate material passes over the weir 18 at the downstream end of the deck 2 to be collected in a hopper and/or onto a stockpiling conveyor.

[0035] The water and undersize material collected in the sump beneath the deck may be pumped to one or more hydrocyclones, at least a portion of the underflow from the one or more hydrocyclones being passed back onto the deck of the dewatering screen, such as onto the material dewatering region of the deck.

[0036] While in the embodiment shown in the drawings the dividing walls are shown as being arranged parallel to the side walls of the deck and one another, it is envisaged that dividing walls may diverge away from each other towards the downstream end of the deck or may converge towards each other.

[0037] In an alternative embodiment of the invention it is envisaged that a single dividing wall may be provided, extending from the end wall of the deck to divide the deck into a single material dewatering region and a single water drainage region.

[0038] The width of the material dewatering region D may be greater than the width of the water drainage region or the sum of the widths of the water drainage regions W1,W2 where two dividing walls are provided. Optionally, the width of the material dewatering region D is at least twice the width of the water drainage region or the sum of the widths of the water drainage regions.

[0039] Reducing the effective size of the material dewatering region of the deck by the provision of one or more dividing walls separating the deck into a material dewatering region and one or more water drainage regions would seem contrary to the accepted principle of increasing the size of the deck available for dewatering material to provide increased capacity. However, by providing separate water drainage regions, with reduced particular concentration, the problems of the prior art blockage of the openings in the deck and resulting restriction in the flow rate of water through the deck are alleviated and the overall capacity of the dewatering screen is greatly increased. Furthermore, the system is effectively self regulating, with more of less water passing through the water drainage regions of the deck depending upon the flow rate and water content of the material supplied onto the dewatering screen.

[0040] In an alternative embodiment is it envisaged that the dewatering screen may be adapted to facilitate the removal of floating material, such as light organics or lignite, from the or each water drainage region via an upstream end of the screen. This could be achieved by partially or fully removing at least a portion of the rear wall 16 of the deck 2 in the water drainage regions W1,W2 or forming suitable apertures or slots in the rear wall in the regions so that water carrying the floating material can flow out of the water drainage regions W1,W2 from an upstream end of the deck. Such water carrying floating material may be passed to further treatment processes, such as a further dewatering screen.

[0041] The invention is not limited to the embodiment described herein but can be amended or modified without departing from the scope of the present invention, which is intended to be limited only by the scope of the appended claims as interpreted according to the principles of patent law including the doctrine of equivalents.