AU673088B2 - Improvements in dewatering chutes for belt conveyors - Google Patents

Description

AUSTRALIA

Patents Act 1990 COMPLETE SPECIFICATION FOR A STANDARD PATENT Name of Applicant(s): Actual Inventors: Address for Service: TASMAN ENGINEERS PTY. LTD.

Paul SUNDSTROM Graham BURLEIGH CULLEN CO., Patent Trade Mark Attorneys, 240 Queen Street, Brisbane, Qld. 4000, Australia.

c a o e o Invention Title: IMPROVEMENTS IN DEWATERING CHUTES FOR BELT CONVEYORS Details of Associated Provisional Applications: Nos. PM0503 filed 12 August 1993 The following statement is a full description of this invention, including the best method of performing it known to us: THIS INVENTION relates to improvements in dewatering chutes for belt conveyors.

The accumulation of excess water in material coal, ore) being carried on belt conveyors is at times a serious problem, particularly in underground mining operatons. Excess water can cause the material to slide back down the conveyor at steeply inclined sections of conveyors.

Consequently measures must be taken to reduce the amount of water in the conveyed material, and the use of dewatering chutes at transfer points between conveyors is one way of achieving this.

In known dewatering chutes, dewatering screens are generally located directly in the chutework carrying the main material flow between the feed and receiving conveyors. These screens, which aria usually very expensive, are in contact with the main material stream, and hence are subject to wear.

Further, as these screens are located in the chutework carrying the main material flow, they are *unable to be used to dewater other secondary material streams, such as those coming from belt cleaning systems.

It is an object of the present invention to provide an improved dewatering chute which overcomes or ameliorates the abovedescribed disadvantages, or which at least provides the consumer with a useful choice.

In one broad form, the present invention provides apparatus for extracting water from a stream of material, comprising an inclined chute for passage of the material stream therealong, a slot extending at least partially across the chute, the chute having a downwardly curved portion defining the upper edge of the slot, whereby in use, water is conveyed at least partially around the curved portion and through the slot while the bulk of the material stream passes over the slot.

Water on the bottom of the material stream (including material fines carried with the water) is drawn around the curved portion by surface tension between the water and the curved portion, while the momentum of the material stream carries it over the slot.

Typically, the inclined chute is located adjacent the discharge end of a belt conveyor, and the material stream is discharged from the belt conveyor onto the chute. The momentum of the material stream discharged from the belt conveyor carries it beyond the slot. However, water which has settled on the conveyor belt below the material tends to follow the belt around the end pulley due to surface tension between the water and belt. The water and material fines separate from the 15 material stream and land above the slot. The water (and i° o fines) flow around the curved portion of the chute and through the slot.

In addition, or alternatively, the lower end of the chute has a downwardly curved portion, and a transverse barrier member is located a predetermined distance downstream from this curved portion. The momentum of the material stream travelling down the chute carries it over the barrier member, but water at the ,...bottom of the stream is conveyed at least partially around the curved portion onto the upstream face of the barrier member.

The barrier member may be provided with an upper flexible flap which, if struck by larger portions of the material stream having a lower trajectory, bends to permit those larger portions to pass over the barrier member.

Preferably, a collection tray is located under the inclined chute to collect water and other material passing through the slot and/or down the upstream face of the barrier member. The collected material is passed to a remote screening station containing a dewatering screen. Water and fines pasing through the screen are treated to extract water which is then pumped onto the collection tray to flush material collected thereon to the screen.

The collection tray is preferably large enough to collect material scraped from the conveyor belt by belt cleaning devices.

Since water and material fines are separated from the main material stream before passing to the remote dewatering screen, the screen is not abraded by the main material flow. Furthermore, the screen can collect material from a number of sources.

In order that the invention may be more fully understood and put into practice, an embodiment thereof will now be described by way of example, with reference 0: to the accompanying drawing which is a schematic '668 15 sectional elevational view of a dewatering chute.

As shown in the drawing, a dewatering chute 3 is located between a feed conveyor 2 and a receiving conveyor 16. A stream of material 1 leaving the feed conveyor belt 2 has a trajectory which causes the material to impact the dewatering chute 3 at a region 4 some distance from the jib pulley 5 of conveyor 2.

Free water in the stream of material, having settled on the belt 2 below the bulk of the material, 0* 0. tends to follow the belt 2 around the pulley 5 due to surface adhesion of the water to the belt. Due to the centrifugal action of the pulley 5 and the momentum of e* the water stream (and any fines carried with it), a fan of water/fines is created between the underside of the main material stream and the pulley. Free water/material fines 6 therefore separate from the main material stream, and impact higher up the chute 3, closer to the jib pulley The water (and any material fines) 6 flow down the chute 3 and are intercepted by a transverse slot 7 extending across substantially the whole width of the dewatering chute 3. The water/fines 6 are drawn by surface tension around a shaped plate 8 which forms the upper edge of slot 7 in the bottom of the chute 3. The water/fines flow through the slot 7 and onto a central collection tray 9 by way of a guide plate/tray 10 (as can be seen in the drawing).

The shaped plate 8 is of a similar width to the slot 7, and its curvature is selected so that it retains the water thereon by surface tension.

After the main material stream 1 has landed on the chute 3, its momentum carries it past the lower end of the chute 3 as a projected stream 27. Additional free water from the main material stream (and further material fines) 11 are separated from the continuing material stream 27 by a second shaped plate 12. The water 11 (including any fines carried therewith) clings to the curved plate 12 by surface tension, and is directed onto 15 the upstram face of a guide plate or barrier 13, which passes it to the central collection tray 9. Again, having regard to the speed and characteristics of the materials stream, the shaped plate 12 is curved so that the water 11 is retained thereon by surface tension.

20 The second shaped plate 12 also extends to substantially across the whole width of the chute 3.

The barrier-like guide plate 13 is provided with a flexible flap 14 at its upper end. This flap 14 intercepts water and material fines which have a lower trajectory than material steam 27. However, if large lumps of material 15 in the material stream 27 strike the flap 14, the flap deflects or bends to permit the large lumps of material to pass through to the receiving conveyor 16 with the material stream 27.

Belt cleaners 19, 20 are suitably provided adjacent the jib pulley 5, in accordance with conventional practice. Additional water/material fines streams 17 and 18 scraped from the conveyor belt 2 by belt cleaners 19 and 20 fall to the same central collection tray 9.

Any material which passes between the jib puilley 5 and the dewatering chute 3 will also be collected by collection tray 9.

A spray bar 21 injects water at the top of the central collection tray 9 to flush material collected on the tray to a screening station 22. The screening station 22 comprises a sloping screen 23. Material flushed from collection tray 9 passes over the dewatering screen 23, with the larger particles 24 passing on to the receiving conveyor 16 while the water and fines form a slurry underflow 25 which passes through the screen 23.

The slurry 25 is fed to a treatment system 26 to remove additional fines material 28. The water component 29 extracted from this slurry by the treatment system is then recycled. Namely, a pump pumps the extracted water to the spray bar 21 described above.

The treatment system 26 may be in the form of a settling tank. Alternatively, the treatment system may suitably comprise a cyclone, or the like, for separating water from material fines.

:6 It will therefore be apparent that water is extracted from the material streams by the shaped plates 20 8, 12 and passes to the collection tray 9, and then through the screen 23. Since only fine or light material passes over screen 23, it is not subject to excessive wear. Moreover, the abovedescribed system allows the screen 23, located remote from the main material stream, 6• to be used to dewater secondary material streams such as .6 s those from the belt cleaners 19, The foregoing describes only one embodiment of 66 the invention and modifications which are obvious to those skilled in the art may be made thereto without departing from the scope of the invention. For example, additional slots and shaped plates can be inserted on longer chutes. In addition, the single transverse slot 7 may be replaced by a plurality of staggered slots, each extending only partially across the chute.

Claims (9)

1. Apparatus for extracting water from a stream of material, comprising an inclined chute for passage of the material stream therealong, a slot extending at least partially across the chute, the chute having a downwardly curved portion defining the upper edge of the slot, whereby in use, water is conveyed at least partially around the curved portion and through the slot while the bvlk of the material stream passes over the slot.

2. Apparatus as claimed in claim 1, further comprising screening means located remotely from the 15 inclined chute, and conduit means for receiving water and other materials passing through the slot and conveying said water and other materials to the screening means.

3. Apparatus as claimed in claim 2, wherein the conduit comprises an inclined tray positioned below the slot, and the screening means comprises an inclined dewatering screen located below the lower end of the inclined tray, whereby material is conveyed gravitationally along the tray to the screen.

4. Apparatus as claimed in claim 2 or 3, further comprising treatment means for receiving water and other material filtered by the screening means, said treatment means being adapted to extract water from the filtered material, and pump means for pumping the extracted water onto the conduit means,

5. Apparatus as claimed in any preceding claim, wherein the chute is located adjacent the discharge end of a belt conveyor and the material stream is discharged from the belt conveyor onto the chute, said slot being positioned such that the momentum of the material stream discharged from the belt conveyor carries it beyond the slot, and water carried with the material stream by the belt conveyor is separated Ifom the material stream after discharge from the belt conveyor and falls on to the chute above the slot and is conveyed at least partially around the curved portion through the slot.

6. Apparatus as claimed in claim 5 when appended to any one of claims 2 to 4, further comprising at least one belt cleaning device associated with the belt conveyor, said conduit being positioned below the belt cleaning device to receive water and other materials scraped from the belt conveyor by the belt cleaning device.

7. Apparatus as claimed in any preceding claim, wherein the chute has a second downwardly curved portion at its lower end, said apparatus further comprising a transverse barrier member located below the chute and spaced a predetermined distance downstream from the second curved portion, wherein in use, the momentum of the material stream passing over the lower end of the chute carries it over the barrier member while water flowing down the chute with the material stream is separated from the stream and conveyed at least partially around the curved portion onto the upstream side of the barrier member.

8. Apparatus as claimed in claim 7, wherein the barrier member has a flexible upper portion which is adapted to bend if struck by larger portions of the material stream to permit said larger portions to pass over the barrier member.

9. Apparatus for extracting water from a stream of material, comprising an inclined chute for passage of the material stream therealong, the lower end of the chute having a downwardly curved portion, a transverse barrier member located below the chute and spaced a predetermined distance downstream of its lower end, wherein in use, the momentum of the material stream passing over the lower end of the chute carries it over the barrier member while water flowing down the chute with the material stream is separated from the stream and conveyed at least partially around the curved portion onto the upstream face of the barrier member. Apparatus for extracting water from a stream of material, said apparatus being substantially as hereinbefore described with reference to the accompanying drawing. DATED~ this eighth day of August 1994 TASMAN ENGINEERS PTY, LTD. By their Patent Attorneys CULLEN CO. ABSTRACT A dewatering chute is positioned between a feed conveyor and a receiving conveyor The dewatering chute has a downwardly curved portion (8) defining the upper edge of a slot extending transversely across the chute. A stream of material (1) discharged from conveyor passes over the slot but water sepa:iated from the material stream is carried around the curved portion by surface tension and passes through the slot to a collection tray Water and other material scraped from the conveyor belt (12) by belt cleaning devices (19, 20) are also collected by the collection tray The bottom end of the chute has a downwardly curved portion (12) and a transverse 15 barrier (13) is positioned downstream of the bottom end of the chute. The momentum of material (27) passing along the chute carries it over the transverse barrier (13) on to the receiving conveyor but water separated from the material stream (27) is carried around the curved portion (12) by surface adhesion, and on to the barrier (13) which directs it to collection tray All material collected by collection tray is passed to a screen The collection tray is irrigated by water extracted from the water filtered through the screen (23) while material (24) which does not pass through screen (23) is directed on to the receiving conveyor (16).