FIELD OF THE INVENTION

This invention relates to a feed apparatus for a slurry and in particular to a feed apparatus that can be used to feed slurry from a hydro-excavation or NDD process to a dewatering screen or other recycling or slurry treatment process at an elevated location.

BACKGROUND OF THE INVENTION

Hydro-excavation is a process for performing ground works wherein high-pressure water jets are used to cut and dig earth and a vacuum system is used to suck up the resulting slurry into a storage tank mounted on a vehicle (referred to herein after as a“hydrovac tanker”) for subsequent disposal. The slurry held in the storage tank of such hydrovac tankers must be emptied at a disposal or recycling site.

The slurry collected during such hydro-evacuation process typically comprises 50% free water and 50% solids. Typically such slurry is discharged from the storage tank of the hydrovac tanker into a reception hopper at a disposal or recycling site by hydraulically raising the tank while opening a rear door in the tank, such that the slurry is discharged into the reception hopper under gravity. This typically requires the reception hopper to be positioned at a relatively low level.

However, slurry recycling systems upon which the slurry is to be treated, such as dewatering screens, are typically mounted at a higher level than the reception hopper, for example so that the slurry can be delivered onto the recycling system under gravity and so that separated water and fine material passing through a dewatering screen or other treatment process can collect under gravity in a sump therebeneath. Therefore, it is often required to convey the slurry from the reception hopper to an elevated position via a suitable conveying device.

Due to the high water content of the slurry and the often abrasive nature of the solids entrained therein bucket elevators are considered particularly suitable for this purpose, wherein a series of spaced apart buckets are mounted on an endless belt, chains or like endless elements extending around upper and lower sprockets, pulleys or other guide means driven such that the buckets, filled with the slurry, travel upwardly between the upper and lower sprockets or pulleys between a loading zone adjacent said lower sprocket or pulley and within the reception hopper and a discharge zone adjacent the upper sprocket or pulley, the buckets being inverted in said discharge zone as they pass over the upper sprocket or pulley to discharge material therefrom before returning to said loading zone adjacent the lower sprocket or pulley to be refilled.

However, problems can arise in feeding the slurry to the loading zone of the bucket conveyor. The wet nature of the slurry prevents the use of traditional belt conveyors for transferring the material to the loading zone of the bucket conveyor. Furthermore, solid material in the slurry tends to settle out of suspension in the reception hopper and fall to the bottom of the hopper, away from the loading zone of the bucket elevator. One prior art solution is to use a screw conveyor to feed material from the reception hopper to the loading zone of the bucket elevator, such as disclosed in US 4,534,461. However, the often abrasive nature of hydro excavation waste leads to rapid wear of such screw conveyors.

SUMMARY OF THE INVENTION

According to the present invention there is provided an apparatus for feeding slurry to a recycling or slurry treatment process at an elevated location, said apparatus comprising a reception hopper for receiving slurry from a transport vehicle and a bucket elevator for conveying said slurry from a loading zone in communication with the reception hopper to a discharge zone at an elevated location, wherein said reception hopper comprises a trough having parallel side walls and a bottom wall, said loading zone of said bucket elevator communicating with a first end of said trough, said trough including a movable wall moveable towards said first end of the trough to urge slurry towards the loading zone of the bucket elevator. Preferably said moveable wall extends perpendicular to said side walls of the trough. Preferably drive means are provided for moving said moveable wall towards and away from said first end of the trough. In one embodiment said drive means may comprise a multi-stage ram.

A seal assembly may be provided around a peripheral edge of said moveable wall engaging the side walls and bottom wall of the trough to form a seal thereagainst. Preferably said seal assembly is replaceable.

Elongate guides may be provided along the side walls of the trough for guiding movement of the moveable wall. Said elongate guides may comprise respective guide rails on either side of the trough extending parallel to the side walls of the trough, said moveable wall including carriages engaging said guide rails. The guide rails may be provided at or adjacent upper edges of the side walls of the trough. In one embodiment the guide rails may be provided on lower sides of respective lips extending inwardly from an upper edge of each side wall of the trough.

Preferably a support frame is provided on a rear side of the moveable wall adapted to maintain the moveable wall perpendicular to side walls of the trough. Where provided, said carriages engaging said guides may be provided on an upper side of said support frame, extending perpendicular to the moveable wall and parallel to the side walls of the trough.

The bucket elevator may comprise a plurality of spaced apart buckets mounted on one or more endless elements extending around upper and lower guide means driven such that the buckets travel upwardly between the upper and lower guide means between said loading zone, wherein the buckets can receive material held in the reception hopper, and a discharge zone adjacent the upper guide means, the buckets being inverted in said discharge zone as they pass over the upper guide means to discharge material therefrom before returning to said loading zone adjacent the lower guide means. Said one or more endless elements may comprise an endless belt upon which the buckets are mounted, said upper and lower guide means comprising upper and lower rollers or pulleys upon which the endless belt is mounted. The loading zone of the bucket elevator may be located within the reception hopper at or adjacent said first end of the trough. Each bucket of the bucket elevator may comprise a base, a back wall, lateral walls, and a front wall.

The apparatus may further comprise a dewatering device adjacent a discharge zone of the bucket elevator for receiving slurry therefrom. The dewatering device may comprise a dewatering screen having an apertured deck upon which slurry is deposited from said discharge zone of said bucket elevator, vibration generating means for vibrating said apertured deck whereby undersize material and water passes through said apertured deck and is collected in a sump beneath said apertured deck while oversize material falls from a discharge end of said deck.

BRIEF DESCRIPTION OF THE DRAWINGS

An apparatus for feeding slurry to a recycling or slurry treatment process at an elevated location 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

Figure 1 is a perspective view of a slurry treatment apparatus for treating hydro evacuation waste incorporating a feed apparatus in accordance with an embodiment of the present invention;

Figure 2 is a side view of the apparatus of Figure 1 ;

Figure 3 is an end view of the apparatus of Figure 1 ;

Figure 4 is a further perspective view of the apparatus of Figure 1 ;

Figure 5 is a sectional view on line A-A of Figure 2; and

Figure 6 to 8 are plan views of the apparatus of Figure 1 showing the moveable wall of the reception hopper in different positions. DETAILED DESCRIPTION OF THE DRAWINGS

As illustrated in the drawings, a slurry treatment apparatus for treating hydro evacuation waste, in particular for dewatering said waste, incorporating a feed apparatus in accordance with an embodiment of the present invention comprises a reception hopper 2 adapted to receive slurry discharged from a hydrovac tanker, a dewatering screen 4 mounted on a support frame 6 above a sump 8 and an inclined bucket elevator 10 for conveying slurry from the reception hopper 2 to the dewatering screen 4.

The reception hopper 2 comprises an elongate trough having parallel side walls 12,14 and a bottom wall 15. A movable wall 16 is mounted within the reception hopper 2 adapted to be advanced along the trough towards a loading zone 18 of the bucket elevator 10 at one end of the reception hopper 2 for urging material within the reception hopper 2 towards and into said loading zone 18 of the bucket elevator 10. The bottom wall 15 of the reception hopper 2 may slope downwardly towards the loading zone 18 of the bucket elevator 10.

A resilient seal assembly 20 is mounted on a peripheral edge of the moveable wall 16 forming a liquid tight seal between the moveable wall 16 and the side walls 12,14 and bottom wall 15 of the reception hopper 2. The seal assembly 20 may be replaceable when worn.

A support frame 22 is provided on a rear side of the moveable wall 16. Guide rails 24,26 are provided along lower sides of respective lips 28,30, said lips 28,30 extending inwardly from upper edges of the side walls 12,14 of the reception hopper 2. The guide rails 24,26 extend parallel to the side walls 12,14 of the reception hopper 2. Carriages 32,34 are provided on upper sides of the support frame 22 of the movable wall extending perpendicular to the movable wall 16 and parallel to the side walls 12,14 of the reception hopper, said carriages 32,34 engaging the guide rails 24,26 to guide movement of the moveable wall 16 along the elongate trough defined by the reception hopper 2 and to maintain the moveable wall 16 perpendicular to the side walls 12,14 of the reception hopper 2. The engagement of the carriages 32,34 with the guide rails 24,26 also maintains the seal assembly 20 of the moveable wall 16 in engagement with the side and bottom walls 12,14,15 of the reception hopper 2. The carriages 32,34 may be adapted to run on the guide rails 24,26 without requiring lubrication.

A multi-stage ram 36 or other suitable actuating means is provided for displacing the moveable wall 16 along the reception hopper 2, preferably acting between the moveable wall and a rear wall of the reception hopper.

The bucket elevator 10 comprises an endless belt 38 supported upon upper and lower guide rollers (not shown) within an inclined conveyor support frame 40, a plurality of spaced apart buckets 42 being mounted on the endless belt 38 such that the buckets travel upwardly on an upper run of the belt 38 between the loading zone 18 within an end region of the reception hopper 2, wherein the buckets 42 can receive material held in the reception hopper, and a discharge zone 44 located an an elevated location above the dewatering screen 4, the buckets 42 being inverted in said discharge zone 44 as they pass over the upper guide roller to discharge material therefrom onto a deck 46 of the dewatering screen 4 before returning to said loading zone 18 adjacent the lower guide means on a lower run of the belt 38 to be refilled. Each bucket 42 comprises a base, a back wall, lateral walls, and a front wall as is conventional in the art.

The loading zone 18 of the bucket elevator 10 is defined by an end region of the reception hopper 2, opposite said moveable wall 16. The side walls 12,14 of the reception hopper preferably taper inwardly towards said loading zone 18, the bottom wall 15 of the reception hopper defining a curved sump region 48 through which the buckets 42 pass in close proximity to the bottom wall 18 to ensure that all of the material in the reception hopper 2 is transferred to the dewatering screen 4 via the bucket elevator 10.

In use, with the moveable wall 16 in a fully retracted position, as illustrated in Figure 6, slurry, such as hydro-evacuation waste from a hydrovac tanker, is discharged into the reception hopper 2, flowing into the loading zone 18 of the bucket elevator 10, which is operated to convey the slurry onto the deck 46 of the dewatering screen 4. As the level of the slurry in the reception hopper 2 falls, a point is reached, which may be detected by a level sensor, at which the ram 36 is extended to begin to advance the moveable wall 16 towards the loading zone 18 of the bucket elevator 10, as illustrated in Figure 7, while the bucket elevator 10 continues to convey the slurry to the deck 46 of the dewatering screen 4. The moveable wall 16 pushes any solid material collected in the bottom of the reception hopper 2 towards the loading zone 18 of the bucket elevator. The moveable wall 16 continues to be advanced until it reaches it fully advanced position within the reception hopper 2, as shown in Figure 8. Once the reception hopper has been emptied of slurry by the bucket elevator 10 the bucket elevator 10 is stopped and the ram 36 is operated to return the moveable wall 16 to its full retracted position within the reception hopper 2 before a further batch of slurry is discharged into the reception hopper 2 and the process repeated. While the feed apparatus has been described in the above embodiment in use with a dewatering screen it is envisaged that the feed apparatus in accordance with the present invention may used to convey slurry from a reception hopper to an elevated location in respect of numerous other applications and the apparatus may be modified without departing from the scope of the present invention as defined in the appended claims.