GB2244937A

GB2244937A - Separating apparatus

Info

Publication number: GB2244937A
Application number: GB9112856A
Authority: GB
Inventors: Nicholas Hugh Twomey
Original assignee: DANDEM Manufacturing Ltd
Current assignee: DANDEM Manufacturing Ltd
Priority date: 1990-06-15
Filing date: 1991-06-14
Publication date: 1991-12-18
Anticipated expiration: 2011-06-14
Also published as: GB2244937B; IE900767A1; GB9112856D0; ZA914614B

Abstract

Apparatus for separating water and washed sand comprises a vessel 4 into which the mixture is fed, having a channel 8, of semi-circular cross section, extending therefrom along which water flows to overflow 9. A bucket wheel 15 lifts the sand from vessel 4 to chute 18, each bucket having a mesh base 24 to drain off water. A filter disc 33 rotates upstream of overflow 9, making a seal with channel 8, and is backwashed by water from radial nozzle tube 45. An auger 27 rotates with the disc to return sand to vessel 4. <IMAGE>

Description

The present invention relates to separating apparatus for separating particulate material from a liquid, and in particular, though not limited to separating apparatus for separating fine particles of washed sand from water.

Sand for use for building purposes in general is washed with water. It is important that the sand, and in particular the relatively fine particles of sand, are separated from the washing water. Otherwise, considerable loss of sand occurs. Various separating apparatus are known for separating sand from the washing water. Such separating apparatus, in general, comprises a filter through which the mixture of sand and water is filtered. However, such known apparatus suffer from various problems. One problem in particular is that the filters tend to get blocked.

Where the filters are of a sufficiently wide mesh to avoid blockage of the filter, a considerable loss of relatively fine particles of sand occurs.

Furthermore, the capacity of such apparatus, in general, is relatively limited.

There is therefore a need for separating apparatus which overcomes the problems of known separating apparatus.

The present invention is directed towards providing such separating apparatus.

According to the invention, there is provided separating apparatus for separating particulate material from a liquid, the separating apparatus comprising a sump housing defining an upstream sump, and a channel housing extending from the sump housing, the channel housing defining a downstream channel of substantially semi-circular cross sectional area communicating with and extending in a downstream direction from the sump for draining liquid from the sump, a weir extending across the channel at the downstream end thereof for retaining liquid in the channel, a rotatable member rotatably mounted in the sump carrying a plurality of buckets extending round the periphery thereof for raising the particulate material from the sump and delivering the particulate material into a chute, separating means in each bucket for separating the liquid from the particulate material prior to the particulate material being delivered from each bucket into the chute, an auger conveyor rotatably mounted in the channel and cooperating with the channel housing for returning particulate material into the sump, circular filter means rotatably mounted in the channel and extending transversely thereof intermediate the auger conveyor and the weir for filtering particulate material from the liquid passing therethrough, the filter means sealably engaging an inner surface of the channel housing defining the channel, and being rotatable in the channel about a rotational axis co-inciding with the axis of generation of the channel, at least one cleaning nozzle mounted downstream of the filter means for directing a fluid through the filter means from the downstream side thereof for dislodging particulate material from the upstream side of the filter means, the cleaning nozzle being mounted above the level of the liquid.

In one embodiment of the invention, a plurality of cleaning nozzles are provided for directing an elongated curtain of fluid through the filter means.

Preferably, the cleaning nozzles are mounted on an elongated manifold at spaced apart locations.

Advantageously, the manifold extends from a position substantially adjacent the rotational axis of the filter means to a position adjacent the periphery of the filter means.

In another embodiment of the invention, the auger conveyor is rigidly mounted on an auger shaft rotatable about a rotational axis co-inciding with the axis of generation of the channel, and the filter means is rigidly mounted on the auger shaft.

In another embodiment of the invention, the filter means comprises a hoop-shaped frame having a plurality of radial members extending inwardly therefrom to a hub for engaging the auger shaft, and a filter medium of circular area mounted on the hoop-shaped framework.

Advantageously, sealing means extend from the filter means for sealably engaging the inner surface of the channel housing defining the channel.

In another embodiment of the invention, the rotatable member is rotatable about a rotational axis extending in a transverse direction relative to the rotational axis of the auger conveyor.

Preferably, the rotatable member comprises a circular drum rigidly mounted on a drive shaft, the drive shaft being rotatably mounted in the sump housing.

In another embodiment of the invention, drive means are provided for driving the rotatable member and the auger conveyor and filter means.

The invention will be more clearly understood from the following description of a preferred embodiment thereof, given by way of example only, with reference to the accompanying drawings, in which: Fig. 1 is a front elevational view of separating apparatus according to the invention for separating particulate material from a liquid, Fig. 2 is a plan view of the apparatus of Fig. 1, Fig. 3 is an end view of the apparatus of Fig. 1, Fig. 4 is a sectional front elevational view on the line IV-IV of Fig. 2 of the apparatus of Fig.

1, Fig. 5 is a cross sectional end view on the line V-V of Fig. 1, and Fig. 6 is a sectional plan view on the line VI-VI of Fig. 4 of a detail of the separating apparatus of Fig. 1.

Referring to the drawings, there is illustrated separating apparatus according to the invention indicated generally by the reference numeral 1 for separating particulate material from a liquid, in this case, sand from water. The apparatus 1 comprises a main housing 2 of steel. The main housing 2 comprises a sump housing 3 which defines an upstream sump 4 into which the mixture of sand and water to be separated is delivered. A channel housing 6 extends from the sump housing 3 and defines a downstream channel 8 of semicircular cross section which extends in a downstream direction from the sump 4 for draining water from the sump 4. A weir 9 extends transversely across the channel 8 for maintaining a level of water in the channel 8. A transverse end wall 10 closes the downstream end of the channel 8.An outlet 11 on the downstream side of the weir 9 drains water from the channel 8 having passed over the weir 9. The main housing 2 is supported on a framework 12 extending from a base 14.

A rotatable member, namely, a rotatable drum 15 of steel rigidly mounted on a drive shaft 16 is rotatably mounted in the sump 4. The drive shaft 16 is rotatable in bearings 13 in the sump housing 3. Drive means for driving the drive shaft 16 and in turn the drum 15 in the direction of the arrow A comprises an electrically powered motor (not shown) which drives the shaft 16 through a gear box (also not shown), both of which are mounted on the base 14. A plurality of buckets 17 of steel for delivering sand from the sump 4 to a chute 18 are rigidly mounted around the periphery of the drum 15. The chute 18 is mounted on the sump housing 3 so that as the buckets 17 are moving downwardly, sand in the bucket 17 falls under gravity into the chute 18, through which the sand is delivered for collection. Each bucket 17 comprises side walls 19 and a base 20 extending from the drum 15.A front wall 21 extending from the base 20 and between the side walls 19 defines with the base 20, the side walls 19 and the drum 15 a hollow interior region 22. An open mouth 23 which faces in the direction of motion of the buckets 17 as the drum 15 rotates in the direction of the arrow A provides access to the interior region 22 so that on rotation of the drum 15 sand is scooped from the sump 4 into the interior region 22. Separating means for separating water from the sand in the buckets 17 prior to the sand being delivered into the chute 18 comprises a filter member 24 of gauze material forming portion of the base 20 of each bucket 17 (see Fig. 4) so that as each bucket 17 rises out of the water in the sump 4 water commences to drain from the sand through the filter member 24 back into the sump 4.

An auger conveyor 27 of steel rigidly mounted on an auger shaft 28 is rotatable in the channel 8 and cooperates with the channel housing 6 for returning particles of sand from the channel 8 to the sump 4 which are carried with the water through the channel 6 and normally collect in the bottom of the channel 8.

A transverse member 29 is mounted in the channel housing 6 and extends transversely across the channel 8. The auger shaft 28 is rotatable in bearings 30 one of which is carried on the transverse member 29 and the other on the transverse end wall 10. The bearings 30 are mounted so that the rotational axis of the auger shaft 28 and in turn the auger conveyor 27 co-incides with the axis of generation of the inner surface 32 defining the channel 8.

Filter means comprising a disc filter 33 for filtering remaining particles of sand in the water is mounted in the channel 8 intermediate the auger conveyor 27 and the weir 9. The disc filter 33 is rigidly mounted on the auger shaft 28, and rotatable therewith, and extends transversely of the channel 8. The disc filter 33 comprises a hoop-shaped framework 34 of steel rigidly mounted on the auger shaft 28. The hoop framework 34 comprises a circular hoop 35 and a plurality of radial members 36 extending from the hoop 35 to a hub 37 rigidly mounted on the auger shaft 28.

A filter medium, namely, a wire mesh filter 39 is mounted on the hoop framework 34. The wire mesh filter is of circular shape of diameter substantially similar to the diameter of the hoop 35 and is secured to the hoop framework 34 by spotwelds at appropriate points. The outer diameter of the hoop 35 and the diameter of the wire mesh filter 39 is substantially similar to the diameter of the inner surface 32 of the channel 8 with a small clearance to accommodate rotation of the disc filter 33. Sealing means for sealing the disc filter 33 against the inner surface 32 of the channel 8 to prevent the passage of unfiltered water across the disc filter 33 comprises a sealing flange 40 of flexible plastics material which extends from the hoop 35 around the periphery 41 of the hoop 35.A ring 42 is secured to the hoop 35 by screws 43 and clamps the flange 40 in position between the ring 42 and the hoop 35. Drive means for driving the auger shafts for in turn rotating the auger conveyor 27 and the disc filter 33 in the direction of the arrow B comprises a motor (not shown) which drives the auger shaft 28 through a gear box (also not shown) both of which are mounted on the base 14.

A manifold 45 mounted on a bracket 46 extending upwardly from the channel housing 6, extends from a position substantially co-inciding with the axis of rotation of the disc filter 33 to the periphery 47 of the disc filter 33 on the downstream side thereof. A plurality of cleaning nozzles 49 spaced apart along the manifold 45 extend from the manifold 45 and direct jets of cleaning fluid, in this case, water through the mesh filter 39 from the downstream side for dislodging particles of sand from the upstream side of the mesh filter 39. The nozzles 49 are arranged so that the jets of water generated by the nozzles 49 essentially form a transverse curtain of water which extends substantially radially of the disc filter 33 from adjacent the axis of rotation of the disc filter 33 to the periphery 47 of the disc filter 33.The manifold 45 and nozzles 49 are arranged on the side of the channel 8 so that as the disc filter 33, rotating in the direction of the arrow B, leaves the water in the channel 8, the mesh filter 39 is subjected to the jets of cleaning water. Water under pressure is delivered from a high pressure source (not shown) through a pipe (not shown) to the manifold 45.

The mesh size of the filter 39 depends on the size of particles that are to be recovered. In other words, the maximum size of particles which may be discharged with the water through the outlet 11 from the channel 8. In practice, where it is desired to retain the maximum size of particle in the water discharged through the outlet relatively low, it is envisaged that the filter 39 will be of wire mesh with a mesh size of approximately 100 microns. Although, it is envisaged that the mesh size may be 200 microns in many cases. Needless to say, as mentioned above, any appropriate mesh size may be used depending on the permissible particle size which may be discharged through the outlet 11.

In use, a mixture of sand and water to be separated is delivered into the sump 4 of the separating apparatus 1. In practice, the separating apparatus 1 works continuously and the water and sand is continuously delivered into the sump 4 at a rate at which the separating apparatus 1 can cope. The buckets 17 rotating with the drum 15 scoop up sand and water from the sump 4. The sand is separated from the water by the filter members 24 in the base 20 of each bucket 17. As the buckets 17 commence to move downwardly, sand in the buckets 17 is discharged under gravity through the open mouths 23 into the chute 18. Water with some sand particles entrained therein flows from the sump 4 through the channel 8. As the auger conveyor 27 rotates, some of the sand particles which collect in the base of the channel 8 are returned to the sump 4. Other particles which remain entrained in the water are filtered out of the water by the disc filter 33. The cleaning nozzles 49 directing a curtain of high pressure water at the disc filter 33 dislodge particles of sand collected on the upstream side of the filter 39 as the filter 39 rotates out of the water. The filtered water then passes over the weir 9, where it is discharged through the outlet 11.

While the filter means has been described as comprising a disc filter formed by a mesh filter mounted on a hoop framework, any other construction of disc filter may be provided. Indeed, other filters besides a mesh filter may be used. Needless to say, while specific mesh sizes for the mesh filter have been described, mesh filters of other size may be used.

Further, while a plurality of cleaning nozzles have been described as being mounted on a manifold, in certain cases, it is envisaged that a single cleaning nozzle may be sufficient. While it is preferable, it is not essential that the cleaning nozzles be arranged to direct a jet of water which extends substantially radially relative to the disc filter from the rotational axis thereof to the periphery. Any other suitable arrangement of cleaning nozzle and jet of cleaning fluid may be used. Needless to say, while the cleaning fluid has been described as being water, any other suitable cleaning fluid may be used.

Indeed, in certain cases, it is envisaged that high pressure air may be used.

Further, it will be appreciated that any other construction of rotatable member besides that described may be used, and it will also of course be appreciated any other suitable auger conveyor besides that described may likewise be mounted in the channel.

Claims

1. Separating apparatus for separating particulate material from a liquid, the separating apparatus comprising a sump housing defining an upstream sump, and a channel housing extending from the sump housing, the channel housing defining a downstream channel of substantially semi-circular cross sectional area communicating with and extending in a downstream direction from the sump for draining liquid from the sump, a weir extending across the channel at the downstream end thereof for retaining liquid in the channel, a rotatable member rotatably mounted in the sump carrying a plurality of buckets extending round the periphery thereof for raising the particulate material from the sump and delivering the particulate material into a chute, separating means in each bucket for separating the liquid from the particulate material prior to the particulate material being delivered from each bucket into the chute, an auger conveyor rotatably mounted in the channel and cooperating with the channel housing for returning particulate material into the sump, circular filter means rotatably mounted in the channel and extending transversely thereof intermediate the auger conveyor and the weir for filtering particulate material from the liquid passing therethrough, the filter means sealably engaging an inner surface of the channel housing defining the channel, and being rotatable in the channel about a rotational axis co-inciding with the axis of generation of the channel, at least one cleaning nozzle mounted downstream of the filter means for directing a fluid through the filter means from the downstream side thereof for dislodging particulate material from the upstream side of the filter means, the cleaning nozzle being mounted above the level of the liquid.

2. Separating apparatus as claimed in Claim 1 in which a plurality of cleaning nozzles are provided for directing an elongated curtain of fluid through the filter means.

3. Separating apparatus as claimed in Claim 2 in which the cleaning nozzles are mounted on an elongated manifold at spaced apart locations.

4. Separating apparatus as claimed in Claim 3 in which the manifold extends from a position substantially adjacent the rotational axis of the filter means to a position adjacent the periphery of the filter means.

5. Separating apparatus as claimed in Claim 3 or 4 in which the manifold is mounted on a mounting bracket extending from the channel housing.

6. Separating apparatus as claimed in any preceding claim in which the auger conveyor is rigidly mounted on an auger shaft rotatable about a rotational axis co-inciding with the axis of generation of the channel, and the filter means is rigidly mounted on the auger shaft.

7. Separating apparatus as claimed in Claim 6 in which the filter means comprises a hoop-shaped frame having a plurality of radial members extending inwardly therefrom to a hub for engaging the auger shaft, and a filter medium of circular area mounted on the hoop-shaped framework.

8. Separating apparatus as claimed in any preceding claim in which sealing means extend from the filter means for sealably engaging the inner surface of the channel housing defining the channel.

9. Separating apparatus as claimed in any preceding claim in which the rotatable member is rotatable about a rotational axis extending in a transverse direction relative to the rotational axis of the auger conveyor.

10. Separating apparatus as claimed in any preceding claim in which the rotatable member comprises a circular drum rigidly mounted on a drive shaft, the drive shaft being rotatably mounted in the sump housing.

11. Separating apparatus as claimed in any preceding claim in which drive means are provided for driving the rotatable member and the auger conveyor and filter means.

12. Separating apparatus substantially as described herein with reference to and as illustrated in the accompanying drawings.