GB2309922A - Separator for particulate solids - Google Patents

Abstract

A particle separator is provided which uses a plurality of different diameter discs with the smaller discs mounted between larger diameter discs to effect a separation of different size range materials in the feed. The oversize material is retained on the outside of the larger diameter disc; the intermediate size material is retained on the outside of the smaller diameter discs; and the undersize material passes between the larger and smaller diameter discs. Tines are used to separate the oversize, intermediate and undersize materials from one another.

Description

SEPARATOR The invention relates to a separator for particulate solids, particularly but not exclusively for hetrogenious minerals such as coal or metallic ores, wherein particles cf selected dimensions are to be separated from differently dimensioned material. The apparatus may also be used for classifying waste material, paper pulp and the like.

Conventional sizing apparatus, for example as disclosed in GB448838 or GB1087921 include screens composed of interlocking arrays of eccentric rotating discs. Such apparatus contains many moving parts and is complex, expensive and liable to breakage, particularly when using coarse minerals.

According to the present invention a particle separator includes: A rotor comprising a multiplicity of small discs mounted for coaxial rotation, a multiplicity of large discs having a greater radial dimension than the small discs and being mounted for rotation coaxillay with the small discs, the small discs being located between the large discs via a spacer disc.

A feed adapted to provide a flow of particulate material impinging said rotor.

A collector having a multiplicity of tines arranged in spaced relation to receive the large discs, ends of the tines being arranged to co-operate with edges of the small discs to collect material having a dimension allowing passage between the large discs but preventing passage between the small discs.

The present invention provides a simple and efficient means of separating particulate materials. The need for a sizing bed is obviated, with consequent reduction in costs and - liability to failure. Wet or dry material can be efficiently separated.

The ends of the tines may abut the edges of the discs Alternatively they may be spaced from them, centrifugal force serving to propel a stream material outwardly rrom the centre of the rotor towards the collector. The collector may be positioned to catch correctly sized material taking into account the action of gravity on the outwardly moving stream.

A single rotor is preferred, although a succession of two or more apparatus in accordance with the invention ma be used to make successive separations from a flow of material.

The feed of unseparated material is preferably directed towards the rotor, more preferably towards the axis thereof, that is choke or partial choke feed. A tangential flow is Aot preferred for efficient separation. A free flow of unseparated material, that is under gravity, is preferred.

The large and small discs may be disposed of altel-natively upon the rotor. Alternatively the discs may be arranged in any convenient arrangement to suit the size analysis of the particulate material, for example each large disc may be separated by two or more small discs. The rotor may have an axle upon which the discs are mounted. Alternatively an axle may carry a drum upon which the discs are mounted, the drum having a diameter substantially larger than that of an axle, for example up to im.

More than two sizes of discs may be employed.

Intermediate having a dimension between that of the large and small discs may be disposed between the latter upon the rotor. A plurality of collectors may have tines arranged to collect material from the edges of each of the intermediate discs.

A cleansing collector may be provided to clean the rotor during each revolution. The tines of the cleansing collector preferably pass between all of the discs to remove any particles lodged between them. The cleansing collector may be located at any convenient position between the first collector and feed during rotation of the rotor.

The discs are preferably circular. In a preferred embodiment of the invention, the large discs are provided with a segment removed to form a peripheral notch. This prevents oversize pieces of material from becoming seated upon the rotor by engaging such pieces and impelling them on the rotcr.

In a first preferred embodiment of the invention all of the discs are arranged to rotate at the same speed and relay be secured on a common axle.

In a second preferred embodiment of the invention selected discs or disc segments may rotate at a different speed or may be stationary. This has the advantage of reducing adhesion of material between the rotors.

The invention is further described by means of example but not in any limitative sense, with reference to the accompanying drawings of which: Fig 1 is a schematic elevation of apparatus in accordance with the invention.

Fig 2 shows the rotor in plan view.

Fig 2a shows an alternative rotor.

Fig 2b shows cross-sections of four alternative rotors.

Fig 2 is a plan view an end elevation of a further alternative rotor.

Fig 3 shows an alternative embodiment of the invention having an adjustable collector.

Fig 3a illustrates an alternative embodiment of the invention having three collectors.

Fig 3b shows the embodiment shown in Fig 3a with an alternative location of the cleaner.

The apparatus shown in Figs 1 and 2 comprises a conveyor 8 arranged to deposit particulate material, such as coal upon a spreader or collector plate 1. The spreader 1 is arranged to distribute material evenly across the surface of a curved feed chute 2 and arranged to give a "choke" or "partial choke" feed to the rotor 3. The spreader plate is provided with an end pivot and adjustable portion la to control the flow to the rotor. The rotor as shown in Fig 2, comprises an axle 6 carrying a multiplicity of circular discs. Alternate discs.3a have a larger radius than smaller discs 3b disposed between them. Each set of discs is separated by a spacer 3c.

In use of the apparatus material having a dimension less that the separation between the small and large rotors can pass between them and fall into a chute 9. Large particles of material which cannot pass between the large plates 3a is deflected from the periphery of the rotor into a second chute 10. Material having a dimension such that it may pass between the large discs 3a but not between the small discs 3b is collected by a collector 4 having tines which pass between the large discs and abut the edges of the small discs. This intermediate sized material may be collected in the chute 10 with the larger material or may be gathered elsewhere.

cleanser 5 has tines arranged o pass between all of the discs and abut the surface of the spacer 3c. The cleanser may be located downstream of the collector 4 at any position upstream of the chute 2. For example vertically downwardly or horizontally as shown in Fig 1.

A pivoted barrier 7 serves to prevent material from overshooting into the collector 10. A peripheral notch, or serrated circular arc, cut from the edge of some or each of the large discs 3a serves to prevent large pieces of material becoming seated upon the rotor. The impulse given to a large piece by the edge of the rotor causes the piece to be impelled through the barrier into the collector 10.

Because material (under "free flow") enters the rotor assembly as a "choke or "partial choke" feed (ie this could be at 30-45 degrees from the horizontal for example depending on disc aperture, material analysis and moisture) a change of direction is required as material is "conveyed" round the disc periphery.

At this point acceleration of all particles occurs in the new direction of rotation causing: (i) Primary separation of particles upon impingement with the rotor and dependant on the degree of free flow feed conditions and "open area" presented.

(ii)Secondary separation as material changes direction and is accelerated/re-adjusted by the smaller disc tip (circumference) and larger disc sides.

(iii)Tertiary separation of previously adhered fine particles to larger/course material. This is caused through contact/rubbing between "oversize" particles and the disc sides/edges under acceleration and material re-adjustment on the "peripheral conveyor".

All undersized material from (i), (ii) or (iii) is caused to be released between the small discs into the chute 9. Options of larger material are dependent of the position of the collector (4). In such cases the peripheral velocity of the discs could be greater than the flow of material onto the rotor, (in that direction) Fig 2a illustrates an alternative rotor having discs 3c, 3d with radii intermediate between those of the small discs 3b and large discs 3e. Material having a dimension greater than the separation between the outer discs 3e is excluded from the rotor.

Material having a smaller dimension can enter the rotor.

Particles smaller than the separation between discs 3d and 3e but greater than that between discs 3c and 3d may be removed by a collector abutting the edge of the discs 3c. Smaller material which is able to pass between the plates 3c and 3d can similarly be collected by tines of a collector abutting the edges of the discs 3b. Fine material can pass unimpeded through the rotor.

Fig 2b illustrates a disc wherein two peripheral segments are removed or the dic edges curve - serrated to eject large particles from the rotor. The angular extent of the nodel may be determined by the size and shape of material. For example pieces of slate may require use of comparatively large notches or serrations. It is preferred that all of the material to be separated can pass between the largest discs, only exceptionally large pieces requiring use of the notches. The elliptical disc shown in the lower part of the figure may be used alternatively to achieve the same function.

Fig 2c shows a plan view and elevation of an alternative arrangement for separating fine material from larger pieces. The larger and smaller discs 20 and 21 are formed as a unitary construction so as to present a series of grooves into which fine matter may pass. Coarse material may be removed from the surface of the rotor by a collector 22. (The disc 20/21 being enclosed by larger carrying discs 30). Fig 3 illustrates a modification of the invention having a collector movable about a pivot 14 to adjust the radius of the ends of the tines between a first position adjacent the edge of the rotor and a second position adjacent smaller discs 3b.

This allows the size of material collected to be adjusted as required. The speed of the rotor may also be adjusted to further control the degree of separation, a slower speed increasing the degree of separation. Variable degrees of separation is not readily achieved with previously known separation apparatus. In addition the collector may be moved radially around the rotor as shown at 33. This allows the position of the ends of the tines to be adjusted to compensate for the effect of gravity or the stream of material propelled from the rotor.

Fig 3a shows a separator having three collectors 30, 31 , 32 arranged to collect different fractions from the differently dimensioned discs.

Fig 3b shows that the cleansing scraper 5 may be located immediately adjacent the feed, alternatively to the arrangement shown in Fig 3a. This allows fine material to fall freely from the rotor.

In alternative embodiments of the invention the spacing between some or all of the discs may be adjustable to regulate the sizes of particles separated.

Claims (16)

Claims:

1. A particle separator including: a) a rotor comprising a multiplicity of small discs mounted for coaxial rotation, a multiplicity of large discs having a greater radial dimension that the small discs and being mounted for rotation coaxially with the small discs, the small discs being located between the large discs via a spacer disc; b) a feed adapted to provide a flow of particulate material impinging said rotor; c) a collector having a multiplicity of tines arranged in spaced relation to receive the large discs, ends of the tines being arranged to co operate with edges of the small discs to collect material having a dimension allowing passage between the large discs but preventing passage between the small discs.

2. A separator according to claim 1 in which the large and small discs are disposed alternatively upon the rotor.

3. A separator according to claim 1 in which each large disc is separated by two or more small discs.

4. A separator according to any of claims 1 to 3 in which more than two sizes of discs are employed.

5. A separator according to any preceding claim in which the rotor has an axle upon which the discs are mounted or in which an axle carries a drum upon which the discs are mounted.

6. A separator according to any preceding claim in which the feed of unseparated material is directed towards the axis of the rotor.

7. A separator according to any preceding claim in which two or more rotors are used to make successive separations from a flow of material.

8. A separator according to any preceding claim in which intermediate discs having a dimension between that of the large and small discs are disposed between the latter upon the rotor.

9. A separator according to claim 8 in which a plurality of collectors have tines arranged to collect material from the edges of each of the intermediate discs.

10. A separator according to any preceding claim in which a cleansing collector is provided to clean the rotor during each revolution.

11. A separator according to any preceding claim in which the large discs are provided with a segment removed to form a peripheral notch or serrated circular arc.

12. A separator according to any preceding claim in which selected discs or disc segments may rotate at a different speed or are stationary.

13. A method of separating material using the separator of any preceding claim.

14. A method according to claim 13 in which the material is coal.

15. A separator substantially as described herein, with reference to the drawings.

16. A method of separating material substantially as described herein.