GB2177624A

GB2177624A - Separating or cleaning particulate material

Info

Publication number: GB2177624A
Application number: GB08518108A
Authority: GB
Inventors: Boon Lek Chong; Huan Su Wong
Original assignee: Individual
Current assignee: Individual
Priority date: 1985-07-18
Filing date: 1985-07-18
Publication date: 1987-01-28
Also published as: GB8518108D0

Abstract

Particulate material is conveyed through a rotating conduit 1 by helical vanes 8 against an opposing flow of fluid. A pipe 13 extends into a first end 2 of the conduit 1 to deliver fluid and a chute 14 extends into the second end 3 to deliver particulate material. The conduit is inclined to the horizontal to provide a downward gradient for fluid flow and is constricted at the first end 2 to prevent backflow of fluid. Rakes 15 are fixed to the internal walls of the conduit for providing agitation. The conduit is housed in circumferential bearings and driven through a circumferential gear. The apparatus may be used with a fluid which is a liquid or liquid solvent in a cleaning process where cleaned particles emerge at the first end and soiled liquid at the second end. Used in a separating process, coarse particles emerge at the first end and fine particles at the second end. <IMAGE>

Description

SPECIFICATION Improvements in or relating to separating or cleaning particulate matter This invention relates to a process and apparatus for separating or cleaning particulate matter so as, for example, to remove soluble constituents from particulate matter or to separate fine or light particles from heavier or coarser particles.

It is known in the field of mining for example for a separating or cleaning process to include moving particulate matter along a channel and establishing a flow of water or solvent through the channel in the direction of conveyance.

It is also known to use apparatus comprising a vertical cylinder in which there is provided a spirally upward flow of liquid bearing the material to be cleaned which is fed in at the bottom of the cylinder. The material to be cleaned is heavier than the waste material and is thrown against the side of the cylinder and drops against the direction of liquid flow to the bottom of the cylinder where it is withdrawn. The lighter waste is drawn off at the top together with the liquid.

According to the present invention, in a separating or cleaning process, particulate material is conveyed through a rotating conduit by means at least one helical vane within the conduit and a flow of fluid is established through the conduit in a direction opposed to the direction of conveyance. The process may be one of separating or of cleaning or a combination thereof depending on the nature of the material and of the fluid.

The process may use a fluid which is a solvent and preferably the fluid is a liquid. Advantageously the conduit may be inclined to the horizontal to provide a downward gradient for the flow of fluid.

According to the present invention there is further provided apparatus for use in any such process including a conduit having a first end for the admission of fluid and for the emission of processed particulate material and a second end for the admission of unprocessed particulate material and for the emission of fluid and fluid borne particles, which conduit has at least one helical vane disposed along its length and extending radially inwards from the inner wall thereof so as to convey particulate material from the second end to the first end upon rotation of the conduit.

It will be appreciated that the direction of rotation of the conduit must be matched to the handedness of the helical vane to produce conveyance in the required direction, a right handed vane requiring anticlockwise rotation of the conduit as viewed from the second end towards the first end.

The vane or at least one of the vanes may advantageously be perforate to allow passage of fluid and fine particles in the direction of fluid flow.

In a preferred embodiment a pipe extends into the conduit through the first end and is adapted for the discharge of fluid at one or more locations spaced from the first end so as to minimise loss of fluid from the first end.

Similarly a chute may extend into the second end for the admission of particulate material which is to be processed.

Both pipe and chute must not foul the vane or vanes so that the inward radial extent of the vanes is limited to provided a clear space around the longitudinal axis of the conduit.

Preferably the conduit is generally cylindrical and may be inclined to the horizontal for downhill flow of fluid.

In a preferred embodiment of the invention the conduit includes a constriction adjacent the first end to prevent the back flow of fluid, the construction being formed by the abuttment of two frustroconical portions arranged such that a first frustroconical portion at the first end tapers towards the second end and the second frustro-conical portion tapers towards the first end.

The apparatus may include a plurality of cylindrical portions of differing radius, with or without the frustro-conical portions described above.

In a preferred embodiment, the conduit includes rakes which are fixed to the internal surface of the conduit whereby material is urged to rotate with the conduit walls and is thereby agitated. Conveniently the rakes comprise netting which acts as a sieve to allow the passage of fluid and fine particles.

The conduit may conventiently be rotatable within circumferential bearings and driven by means of at least one externally circumferential gear engageable with a driving gear.

An embodiment of the invention will now be described with reference to the accompanying drawing, in which Figure 1 is a partly sectioned side elevation of an apparatus including a conduit with a pair of helical vanes.

The apparatus of Figure 1 has a conduit 1 having a first and second end 2 & 3 respectively. The conduit 1 comprises a single cylindrical portion 4 and a first and second frustro-conical portions 5 and 6 respectively which taper in opposite directions to thereby form a constriction 7 adjacent the first end 2. A pair of right handed helical vanes 8 and 9 extend the full length of the conduit, the vanes 8 and 9 being of equal axial pitch and axially spaced by one half pitch.

The conduit 1 is mounted on circumferential bearings 10 and has a circumferential gear 11 which is driven by a driving gear 12.

A pipe 13 extends through the first end 2 and admits a flow of water beyond the constriction 7 and a chute 14 extends through the second end 3 to admit particulate material (not shown).

The conduit is inclined to the horizontal by an angle A so as to provide a downward gradient for the flow of fluid.

Rakes 15 comprising netting are fixed to the internal surface of the conduit 1 and extend axially between the vanes 8 and 9.

In use in a process for cleaning crushed rock (not shown) of its clay or fine content with water for example the conduit 1 is rotated anti-clockwiseas viewed along its longitudinal axis from the second end 3 to the first end 2. Rock admitted through the chute 14 is conveyed towards the first end 2. Water flows through the pipe 13 into the conduit and washes the rock which is agitated by action of the vanes 8 and the netting so that washed rock emerges at the first end 2 and soiled water carrying the clay and fine content at the second end 3.

A suitable speed of rotation for this process is approximately 1/2 to 2 revolutions per second so that the particulate matter is conveyed towards the first end moving along the lower side of the conduit as it rotates. The speed of rotations is chosen such that the centrifugal force produced by rotation is not sufficient to make the material adhere circumferentially to the inner surface of the conduit throughout a complete rotation.

In a process for separating material into coarse and fine constituents, material admitted through the chute 14 is separated both by centrifugal action and by the combined effects of agitation and the opposing water flow which carries fine particles towards the second end. Thus coarse particles emerge at the first end of the conduit and water borne fine particles at the second end thereby achieving separation.

Further examples of specific uses of the apparatus are in washing and extracting sand, the washing of sea sand to remove its salt content, and the separation of tin ore and sand from clay.

Claims

1. A separating or cleaning process in which particulate material is conveyed through a rotating conduit by means of at least one helical: vane within the conduit and wherein a flow of fluid is established through the conduit in a direction opposed to the direction of conveyance.

2. A process as claimed in claim 1 wherein the fluid is a solvent.

3. A process as claimed in either of claims 1 and 2 wherein the fluid is a liquid.

4. A process as claimed in any preceding claim wherein the conduit is inclined to the horizontal to provide a downward gradient for the flow of fluid.

5. Apparatus for use in a process as claimed in any preceding claim including a conduit having a first end for the admission of fluid and for the emission of processed particulate material and a second end for the admission of unprocessed particulate material and for the emission of fluid and fluid borne particles, and means for rotating the conduit in which the conduit has at least one helical vane disposed along its length and extending ratially inwards from the inner wall thereof so as to convey particulate material from the second end to the first end upon rotation of the conduit.

6. Apparatus as claimed in claim 5 wherein the conduit is generally cylindrical.

7. Apparatus as claimed in either of claims 5 and 6 wherein the conduit is inclined to the horizontal to provide a downward gradient for the flow of fluid.

8. Apparatus as claimed in any of claims 5 to 7 wherein the or at least one of the vanes is perforate.

9. Apparatus as claimed in any of claims 5 to 8 wherein a pipe extends into the conduit through the first end and is adapted for the discharge of fluid at one or more locations spaced from the first end.

10. Apparatus as claimed in any of claims 5 to 9 wherein a chute extends into the conduit through the second end for the admission of particulate material.

11. Apparatus as claimed in any of claims 5 to 10 wherein the conduit includes a constriction adjacent the first end.

12. Apparatus as claimed in claim 11 wherein the constriction is formed by the abuttment of two frustro-conical portions of the conduit arranged such that a first frustro-conical portion at the first end tapers towards the second end and the second frustro-conical portion tapers towards the first end.

13. Apparatus as claimed in any of claims 5 to 12 wherein the conduit includes a plurality of cylindrical portions of differing radius.

14. Apparatus as claimed in any of claims 5 to 13 wherein rakes are fixed to the internal surface of the conduit.

15. Apparatus as claimed in claim 14 wherein the rakes comprise netting.

16. Apparatus as claimed in any of claims 5 to 15 wherein the conduit is rotatable within circumferential bearings.

17. Apparatus as claimed in claim 16 wherein the conduit is rotatable by means of at least one externally circumferential gear engageable with a driving gear.

18. Apparatus substantially as hereinbefore described with reference to the accompanying drawing.