AU666963B2 - Screening apparatus - Google Patents

Description

AUSTRALIA

Patent Act COMPLET SPECIFICATION

(ORIGINAL)

Class I j696% nt. Class Application Number: Lodged: Complete Specification Lodged: Accepted: Published: o

I

r Priority: Related Art: Names(s) of Applicant(s): LETTELA PTY. LTD.

Actual Inventor(s): RAYMOND MAXWELL WOODGATE RONALD JAMES LETTEN Our Address for service is: PHILLIPS ORMONDE FITZPATRICK Patent and Trade Mark Attorneys 367 Collins Street MELBOURNE, Australia 3000 Complete Specification for the invention entitled: SCREENING APPARATUS The following statement is a full description of this invention, including the best method of performing it known to applicant(s): 1 0804N 2 SCREENING APPARATUS This invention relates generally to apparatus for centrifuge screening of ores, and in particular to a screening basket for such an apparatus. The basket and apparatus are applicable for dewatering ore slurries, such as coal slurries, and it will be convenient to hereinafter disclose the invention in relation to that exemplary application. It is to be appreciated, however, that the basket and apparatus are not limited to that application., Centrifuge screening apparatus are widely used in the processing of mined ores in order to extract a mine product.

One such apparatus typically includes a frusto-conical shaped screening basket, having a wedge wire screening wall. The basket is mounted horizontally on its central axis within the apparatus for both rotation about that axis as well as horizontal vibration. In operation, wet solids or slurries are continuously introduced through a feed inlet into the rotating and vibrating basket at the smaller feed end. Solids within the slurry are centrifugally retained by the screening wall, although basket vibration cause them to be transported along the basket to the larger discharge end wheie they are discharged. Water and fines in the slurry pass through the wedge wire screening wall due to high centrifugal forces developed within the rotation basket. As a cesult, good 2. dewatering and separation of fines from the solids can be achieved on a continuous basis with the apparatus.

The screening basket is constructed with a metal skeletal frame supporting a wedge wire screening wall. The wall is welded to the frame so that the basket is a rigid unitary structure intended to withstand a heavy continuous workload during a reasonable working life. However, the workloads usually quickly lead to screening wall wear, as well as basket damage. The abrasive slurries in continuous contact with the screening wall cause wedge wire wear, and can also cause critical wall damage. Moreover, the vibration of the basket can lead to fatigue damage, particularly in connection zones between the wedge wire and skeletal frame.

The unitary structure of baskets currently in use inhibits their economical repair or reconditioning.

Consequently, baskets that have been worn or damaged to an 3 extent effecting their screening ability are usually removed from the apparatus and discarded for replacement by a completely new basket. That is so even though the wear or damage to a basket may be localised, or at least does not extend throughout the basket screening wall.

Moreover, if the wear or damage is of a nature that justifies basket repair, that basket must usually be removed from the apparatus to attend to the repair. As a consequence, the apparatus is less productive which adds to overall ore processing costs.

It is an object of the present invention to provide an improved screening basket.

A further object of the present invention is to provide a screening basket that lends itself to economical repair and reconditioning.

Another object of the present invention is to provide a screening basket that can undergo at least some repair and reconditioning in situ in the screening apparatus.

.iththse objetmind- Qd provides a screening basket for a centrifuge screenin/ apparatus, including: a generally frusto-conical sh aped basket frame; and, an array of screening elements r ovably mounted on the frame so as to provide a periphera /screening wall within the frame.

Preferably, the basket frame include a series of elongate mounting members spaced apart axi ly along the frame with each mounting member extending ripherally about the frame. The screening elements exten /between at least some of those mounting members and are re asably mounted thereon.

Preferably, between opp ite axial ends of the basket frame the mounting members decrease in radial extent. This provides The basket fr e with a stepped configuration over the axial extent ther of.

In one emboiment, the mounting members are mounting rings. Those ylngs are arranged in pairs spaced axially along the basket rame, and respective screening elements extend between, and are mounted to, the mounting rings of each ring pair./ In this embodiment, the mounting rings of each pair raially coincide. Those ring pairs are also evenly gradt dimfrm n aial end nthr 7 Q. o 3a With those objects in mind, the present invention provides a screening basket for a centrifuge ore screening apparatus, including: a generally frustoconical shaped basket frame having a series of elongate mounting members spaced apart along an axis of the frame with each mounting member extending about a periphery of the frame, the mounting members being arranged in adjacent pairs spaced along the frame axis; and, juxtaposed rows of ore screening elements spaced along the frame axis with each row extending about the frame periphery, the screening element(s) forming each row extending laterally between and being removably mounted to the mounting members of a respective mounting member pair, the rows of ore screening together providing a substantially continuous peripheral screening wall within the basket frame.

Preferably, between opposite axial ends of the basket frame the mounting members decrease in radial extent. This provides the basket frame with a stepped configuration over the axial extent thereof. The stepped configuration of the basket frame provides axial steps between adjacent rows of screening elements so that the screening wall is axially stepped between the opposite axial •ends of the basket frame.

In one embodiment, the mounting members are mounting rings. Those rings are arranged in pairs spaced axially along the basket frame, and respective S 20 screening elements extend between, and are mounted to, the mounting rings of each ring pair. In this embodiment, the mounting rings of each pair radially S. coincide. Those ring pairs are also evenly graduated in nominal diameters from one axial end to another axial end of the basket frame. This provides a generally right, stepped frusto-conical shaped basket frame.

25 Preferably, the screening elements are individually releasably mounted on the basket frame. In this way, each screening element may be individually mounted on the frame and removed therefrom.

4 -of the basket frame. This prov-e-e-s a generally right, stepped frusto-conical shaped basket frame.

Preferably, the screening elements are indj idually releasably mounted on the basket frame. In t 's way, each screening element may be individually mounte on the frame and removed therefrom.

Preferably, the screening ements are arranged in rows axially spaced along the bask frame with adjacent rows being positioned juxtaposed ne another. Each row of screening elements preferbl y extends between adjacent mounting members. T stepped configuration of the basket frame provide axial steps between adjacent rows of screening el ents so that the screening wall is axially stepped between th ppsite ends f the basket Preferably, each screening element has a pair of opposed edge regions. Each edge region engages with a respective mounting member for mounting the screening element thereto.

Preferably each edge region is configured so as to at least partially fit about or into a respective mounting ring. To 2Q that end, at least some of the edge regions each have an elongate mounting recess into which a respective mounting ring interferingly fits for mounting of the respective screening element thereon. Some other edge regions each have an elongate retaining shoulder against which a respective 5. mounting ring interferingly engages for mounting of the screening elements thereon.

Preferably, locking members are provided to releasably lock the screening elements in position on the basket frame.

Those locking members are preferably located within gaps between spaced apart adjacent rows of screening elements, and engage with adjacent screening elements to retain those elements in mounted position on the basket frame. In one embodiment, those locking members are locking strips which releasably interengage with edge regions of adjacent screening elements. Moreover, those locking strips bridge between the TRl^ edge regions so as to close the gaps between adjacent 7 screening element rows.

Uf The following description refers to a preferred embodiment of the screening basket of the present invention.

To facilitate an understanding of the invention, reference is 5 made in the description to the accompanying drawings where the basket is illustrated in that preferred embodiment. It is to be understood that the basket is not limited to the preferred embodiment as hereinafter described and as illustrated in the drawings.

In the drawings: Fig. 1 is a perspective view of a screening basket according to a preferred embodiment of the present invention; Fig. 2 is a cross sectional view through Section II-II of the basket of Fig. 1; and, Fig. 3 is a cross sectional view through Section III-III of the basket of Fig. 1.

Referring to the drawings, there is generally shown a screening basket 1 for a centrifuge screening apparatus (not shown).

The basket 1 includes a generally frusto-conical shaped S" basket frame 2 of a rigid, unitary structure. The frame 2 is of a skeletal configuration and includes a series of elongate mounting members 3 spaced apart axially along the frame 2, and "2Q each extending peripherally about the frame 2.

In this embodiment, the mounting members 3 are mounting rings 4a,4b. Those rings 4a,4b are arranged in pairs spaced axially along the basket frame 2 from a feed end 5 to a discharge end 6 of the basket 1. Adjacent pairs of rings 4a,4b are arranged close to one another.

Five mounting ring pairs 4a,4b are provided in this embodiment, although it should be appreciated that other ring pair numbers may be suitable. One mounting ring 4a of one ring pair is positioned at the feed end 5 of the basket I, whilst one mounting ring 4b of another ring pair is positioned at the opposite discharge end 6 of the basket 1. The remaining three mounting ring pairs 4a,4b are positioned side-by-side along the frame 2 intermediate those end ring pairs 4a,4b.

The mounting rings 4a,4b of each pair are equally, axially spaced apart from one another. Moreover, as shown in Figs. 2 and 3, juxtaposed mounting rings 4a,4b of adjacent ring pairs are axially spaced apart. That spacing is small relative to the spacing of the mounting rings 4a,4b within each pair.

6 The mounting rings 4a,4b within each pair radially coincide. Thus, the rings 4a,4b within each pair are of the same shape and diameter, and have a common central axis X which is the rotation axis of the basket 1. However, the mounting ring pairs 4a,4b are sized relative to one another so that the ring pairs are generally evenly graduated in nominal diameter from the feed end 5 to the discharge end 6 so as to provide a generally right, frusto-conical shaped frame 2.

Thus, the mounting rings 4a,4b and ring pairs provide the frame 2 with a stepped configuration over its axial extent, steps occurring between each mounting ring pair 4a,4b. The diameter of the mounting rings 4a,4b in successive ring pairs increase from the feed end 5 to the discharge end 6.

The mounting ring 4a at the smaller feed end 5 of the basket 1 provides a base flange ring 7 at which the basket 1 can be removably mounted within a screening apparatus. That base ring 7 and mounting is of a conventional construction well known to those skilled in the relevant art.

The mcunting ring 4b at the larger discharge end 6 ot 2G the basket provides a top flange ring 8.

The remaining mounting rings 4a,4b are of circular cross sectional shape, although it should be appreciated that other shapes may also be suitable.

In this embodiment, the mounting rings 4a,4b are manufactured from metal plate or rod, such as mild or :tainless steel.

The frame 2 also includes a plurality of support members 9 for supporting the mounting members 3 in their spaced apart peripheral relation. Those support members 9 are spaced apart aoout the frame 2 and each extends along the frame 2. Each mounting member 3 is rigidly secured to each support member 9 in order to form a rigid unitary frame structure.

The support members 9 are support beams 10 extending between the mounting rings 4a,4b from the feed end 5 to the discharge end 6 of the basket 1.

Each support beam 10 is of a generally stepped configuration consistent with the stepped mounting ring pair arrangement. Each support beam 10 has a stepped inner edge region 11 facing inwardly of the basket frame 2, and the mounting rings 4a,4b are mounted at that edge region 11.

7 Thus, the support beams 10 i-e generally and predominantly positioned radially outwardly of the mounting rings 4a,4b.

In this embodiment, the support beams 10 are manufactured from metal plate, such as mild or stainless steel.

An array of screening elements 12 are removably mounted on the frame 2 so as to provide a peripheral screening wall 13 within the frame 2. The screening elements 12 are individually releasably mounted on the basket frame 2. Thus, each element 12 may be mounted on the frame 2 and removed therefrom without disturbing other elements 12 of the basket i. In this way, individual screening elements 12 may be replaced as necessary without having to completely dismantle the screening wall 13.

The screening elements 12 are arranged in rows axially spaced along the basket frame 2. Adjacent rows are positioned juxtaposed one another with each row extending circumferentially about the frame 2. Thus, the rows of screening elements 12 together present a substantially continuous screening wall 13 within the basket frame 2.

2C Each row of screening elements 12 extends between and is mounted on a respective pair of mounting rings 4a,4b. The stepped arrangement of the mounting ring pairs 4a,4b provides axial steps between adjacent rows of screening elements 12.

The spacing between adjacent mounting ring pairs 4a, 4b, and the sizing of the screening elements 12, is such that adjacent rows of screening elements 12 axially overlap one another as shown in Figs. 2 and 3. That overlapping ensures axial continuity of the screening wall 13 between adjacent screening element rows. Thus, the screening wall 13 is axially stepped between the basket ends 5,6. That stepped arrangement may facilitate removal and replacement of individual screening elements 12, as will become more apparent hereinafter.

Each row of screening elements 12 contains one or more screening elements 12. Thus, in one embodiment, a single element 12 may form each row, whilst in an alternative embodiment a plurality such as four or eight elements may be arranged end-to-end in a row formation. A plurality of elements 12 in each row has an advantage of enabling replacement of smaller individual screening elements 12 within rows as required.

8 Each screening element 12 is elongate and extends longitudinally of each row. In this embodiment, each screening element 12 includes a screening strip 14, generally planar, but at least in use is curved consistent with the basket frame curvature. Each screening strip 14 has screening apertures therethrough for screening materials during basket use. The size and configuration of those apertures will be well appreciated by those skilled in the relevant art.

Each screening element 12 has a pair of opposed longitudinal edge regions 15,16, each of which engages with a respective mounting ring 4a,4b within a respective ring pair, for mounting of the screening element 12. To that end, each edge region 15,16 is configured so as to at least partially fit about or into a respective mounting ring 4a,4b for supporting the element 12 thereon.

One corresponding edge region 16 of each screening S element 12, except those screening elements 12 mounted adjacent the discharge end 6 of the basket i, has an elongate mounting recess 17, such as a mounting groove, extending o.

therealong and into which a respective mounting ring 4b fits.

That fit is a close sliding or interference fit. Each mounting recess 17 is located at a rear of the screening element 12, and opens toward the opposite edge region 15 of the same screening element 12. In this way, the one edge region 16 tends to hook about the mounting ring 4b in a clipping manner in order to support the element 12 thereon.

The screening elements 12 have an L-shaped mounting portion 18 extending rearwardly from the screening strip 14 at each one edge region 16, the mounting recess 17 being defined between the screening strip 14 and mounting portion 18.

The one edge region 16 of each screening element 12 mounted adjacent the discharge end 6 of the basket 1 also has an elongate mounting recess 19 extending therealong and into which the mounting ring 4b at that basket end 6 fits. That fit is a close sliding or interference fit. Again, the mounting recess 19 is located at a rear of the screening elements 12, but opens rearwardly away from the screening strip 14. In this way, the one edge region 16 can be press slid onto the mounting ring 4b which, as indicated above, is a top flange ring 8.

9 The other corresponding edge region 15 of each screening element 12, except the screening elements 12 adjacent the feed end 5 of the basket 1, has an elongate retaining shoulder extending therealong and against which a respective mounting ring 4a engages for mounting of the screening element 12. The retaining shoulder 20 is positioned so as to extend partially about a side of the mounting :ing 4a remote from the mounting ring 4b into which the mounting recess 17 fits. That engagement is a close or interfering engagement. Each retaining shoulder 20 is located at a rear of the screening element 12. In this way, with the mounting recess 17 at the one edge region 16 hooking about one mounting ring 4b of a ring pair, the retaining shoulder 20 at the opposite edge region 15 can engage about the other mounting ring 4a of the same ring pair to firmly retain the element 12 in position extending between the mounting rings 4a,4b of that pair.

The screening elements 12 have a retaining portion 21 extending rearwardly from the screening strip 14 at each other edge region 15 and defining the retaining shoulder 0 The other edge region 15 of each screening element 12 to be mounted adjacent the feed end 5 of the basket 1 is cornstructed for receipt in an elongate retaining recess 22 provided in the mounting ring 4a at that basket feed end As outlined above, that mounting ring 4a is in the form of a base flange ring 7, which is provided with an endless retaining recess 22 into which the other edge region 15 of each screening element 12 fits. That fit is a close sliding or interference fit. The retaining recess 22 opens axially o inwardly of the basket 1 so that the other edge region 15 of a screening element 12 can be press slid into the retaining recess 22, as the one edge region 16 of the same element 12 is hooked about the other mounting ring 4b of the same ring pair.

Where a plurality of screening elements 12 are arranged end-to-end in each row then juxtaposed end regions 23 of adjacent screening elements 12 abut one another to form a continuous screening row. In one embodiment (as shown), the end regions 23 abut in flat end face-to-end face relation. In an alternative embodiment (not shown), those end regions 23 are configured to interengage, and thereby enhance mating of the end regions 23 and minimise their offsetting or other 10 separation during basket use. To that end, the end regions 23 may be provided with tongue and groove or other interengaging p ,rtions.

In this embodiment, the screening elements 12 are composed of a plastics material, such as polyurethane.

Locking members 24 are provided to releasably lock the screening elements 12 in position on the frame 2. Thus, although the screening elements 12 by themselves mount on the mounting members 3, the locking members 24 ensure that the mounting is retained during basket use. In particular, the locking members 24 prevent the slurry being screened in the basket 1 from inadvertently dislodging the elements 12.

Moreover, the locking members 24 act to close gaps 25 defined in step regions between the adjacent rows of screening elements 12.

The locking members 24 include locking strips 26 for extending peripherally about the basket frame 2 between adjacent screening element rows. Those strips 26 are releasably locatable between juxtaposed edge regions 15,16 of adjacent screening element rows, and act to maintain those edge regions 15,16 in engagement with their respective mounting rings 4a,4b. Thus, when the mounting rings 4a,4b are S in position on the frame 2, continuous peripheral gaps 25 are defined at the step regions between the screening element rows, and the locking strips 26 are locatable in those gaps to close them and also urge the edge regions 15,16 to maintain their engagement with the mounting rings 4a,4b.

Each locking strip 26 includes a connection portion 27 for extending into a respective gap 25 between juxtaposed edge regions 15,16 of adjacent screening elements 12 and lockingly engaging those edge regions 15,16. The connection portion 27 extends entirely along the locking strip 26 and, together with the edge regions 15,16, is configured to interengage with the edge regions 15,16. To that end, the edge regions 15,16 and connection portions 27 are provided with tongue and groove connections 28 (as shown) or other connections (not shown).

Each edge region 15,16 has a connection groove 29 extending therealong, those grooves 29 facing one another across the element row gap 25, and each connection portion 27 has a pair of connection tongues 30 extending therealong and projecting 11 in opposite outward directions for seating in respective connection grooves 29.

The connection portions 27 are press fitted into the element row gaps 25 with an interference fit. Moreover, the edge regions 15,16 and/or the connection portions 27 are sufficiently flexible to enable press fitting and pull release of the strips 26, as well as being sufficiently resilient to create forces exerted on the edge regions 15,16 to maintain them in engagement with the mounting rings 4a,4b. In this embodiment, the locking strips 26 are composed of a plastics material, such as polyurethane, to provide the desired flexibility and resilience.

Each locking strip 26 also includes a cover portion 31 for bridging the gap 25 and providing a transition bridge between the screening element rows that inhibits any build up of slurry in the step regions or slurry ingress into the gaps To that end, the cover portions 31 act to seal against S the edge regions 15,16, and provide a transition surface 32 between surfaces of those edge regions 15,16.

Each cover portion 31 has a pair of sealing lip regions 33,34 projecting from the connection portion 27 for sealing engagement with a respective screening element edge region 15,16. That sealing engagement is achieved as a result of the press fitting of the connection portion 27 into the gap Lip regions 33 engaging the screening element 12 closer to the smaller feed end 5 of the basket i, seats in a recess 35 in the edge region 15. In this way, during basket use, the lip region 33 is sheltered from slurry moving over the step region toward the larger discharge end 6 of the basket 1. The other lip region 34, engaging the screening element 12 closer to the discharge end 6 of the basket i, is feathered or tapered toward that discharge end 6. In this way, during basket use, slurry moving over the step region flows uninterrupted onto the downstream screening element row.

In this embodiment, the connection and cover portions 27,31 of each locking strip 26 are formed integral with one another, such as by moulding of the strip 26.

The locking members 24 also include at least one further locking strip 36 for extending peripherally about the basket frame 2 at the discharge end 6 of the basket 1, in order to 12 lock the adjacent screening element row to the mounting ring 4b at that discharge end 6. That locking strip 36 also assists in protecting the mounting ring 4b from wear and damage from solids discharging through the discharge end 6.

Each locking strip 36 engages the screening element edge regions 16 and juxtaposed mounting ring 4b in order to lock them together. To that end, the locking strip 36 includes a connection portion 37 for releasably connecting with the screening element edge region 16. The edge region 16 and connection portion 37 are configured to interengage to achieve that connection. The edge region 16 and connection portion 37 are provided with a tongue and groove connection 38 (as shown), or other connections (not shown). The edge region 16 has a connection groove 39 extending therealong and opening axially outwardly of the basket i, whilst the connection portion 37 has a connection tongue 40 extending therealong for S seating in the connection groove 39. The tongue 40 and groove 39 are of a dove tailed profile to enhance interengagement.

The connection portion 37 is press fitted into the connection groove 39 with an interference fit. To that end, the edge region 16 and/or the connection portion 37 are sufficiently flexible to enable press fitting and pull release of the locking strip 36. In this embodiment, the locking strip 36 is composed of a plastics material, such as polyurethane, to provide the desired resilient flexibility.

Each locking strip 36 also includes another connection portion 41 for releasably connecting with the mounting ring 4b to lock them together. That connection portion 41 is S configured to engage about the mounting ring 4b. To that end, the connection portion 41 has a hooked profile so as to extend from the connection portion 37 engaging the edge region 16 and pass about the mounting ring 4b in a hooking manner. The passage of the connection portion 41 over and about the mounting ring 4b also acts to protectively cover that ring 4b.

In th4s embodiment, the connection portions 37,41 of the locking strip 36 are formed integral with one another, such as by moulding.

Each of the locking strips 26,36 extends entirely about the basket 1 to lock the adjacent screening element 12 in position. However, in an alternative embodiment, several 13 strips 26,36 may be arranged end-to-end along each screening element row. Those several strips 26,36 may coincide with, or overlap between several screening elements 12 forming each element row.

The screening basket 1 of the present invention is used in a screening apparatus in the same manner as conventional baskets. However, the construction of the present basket 1 may reduce fatigue damage. In that regard, the releasable mounting of the screening elements, and less rigid overall construction of the basket, may enable better absorption and dissipation of fatigue forces when compared with existing unitary baskets.

In any event, the releasable mounting of the screteing elements enables ready removal and replacement of those elements upon their wear or damage. Individual element S replacement can be achieved easily and quickly, which in turn S should prolong the effective working life of the basket.

Moreover, element replacement can be attended to while the S basket remains mounted within the screening apparatus.

~Consequently, apparatus down time may be minimised.

Finally, it will be appreciated that various modifications and/or additions may be made to the screening basket and element without departing from the ambit of the present invention as defined in the claims appended hereto.

Claims (18)

1. A screening basket for a centrifuge ore screening apparatus, including: a generally frusto-conical shaped basket frame having a series of elongate mounting members spaced apart along an axis of the frame with each mounting member extending about a periphery of the frame, the mounting members being arranged in adjacent pairs spaced along the frame axis; and, juxtaposed rows of ore screening elements spaced along the frame axis with each row extending about the frame periphery, the screening element(s) forming each row extending laterally between and being removably mounted to the mounting members of a respective mounting member pair, the rows of ore screening together providing a substantially continuous peripheral screening wall within the basket frame.

2. A screening basket as claimed in claim 1, wherein between opposite axial ends of the basket frame the mounting members decrease in radial extent so as to provide the basket frame with a stepped configuration over the axial extent thereof, the stepped configuration of the basket frame providing axial steps between adjacent rows of screening elements so that the screening wall is axially stepped between the opposite axial ends of the basket frame.

A screening basket as claimed in claim 2, wherein the mounting members i of each pair radially coincide. 20

4. A screening basket as claimed in any preceding claim, wherein the mounting members are mounting rings.

A screening basket as claimed in claim 4, wherein the mounting ring pairs are evenly graduated in nominal diameters from one axial end to another axial 25end of the basket frame, thereby to provide a generally right, stepped frusto- conical shaped basket frame.

6. A screening basket as claimed in any preceding claim, wherein the basket frame further includes a plurality of support members for supporting the mounting members in their spaced apart peripheral relation, the support members being spaced apart about and extending along the basket frame, with the mounting members being rigidly secured thereto.

7. A screening basket as claimed in claim 6 when appended to claim 2, wherein each support member includes a support beam of generally stepped .C k configuration consistent with the stepped mounting member configuration, and the mounting members are mounted toward an inner edge region facing inwardly of the basket frame so that the support beams are predominantly positioned radially outwardly of the mounting members.

8. A screening basket as claimed in any preceding claim, wherein the screening elements are individually releasably mounted on the basket frame, whereby each screening element may be individually mounted on the frame and removed therefrom.

9. A screening basket as claimed in any preceding claim, wherein each screening element has a pair of opposed edge regions, each of which engages with a respective mounting member for mounting the screening element thereto.

A screening basket as claimed in claim 9 when appended to claim 4 or any claim appended thereto, wherein each edge region is configured so as to at least partially fit about or into a respective mounting ring.

11. A screening basket as claimed in claim 10, wherein at leat some of the edge regions each have an elongate mounting recess extending therealong and into which a respective mounting ring interferingly fits for mounting of the respective screening element thereon.

12. A screening basket as claimed in claim 10 or 11, wherein at least some of i the edge regions each have an elongate retaining shoulder extending therealong :i 20 and against which a respective mounting ring interferingly engages for mounting of the screening elements thereon.

13. A screening basket as claimed in any preceding claim, and further including locking members releasably locking the screening elements in position on the basket frame. 25

14. A screening basket as claimed in claim 13, wherein adjacent rows of the screening elements are spaced apart so as to define gaps therebetween, and the locking members are located within the gaps and engage with adjacent screening elements to retain those screening elements in mounted position on the basket frame.

15. A screening basket as claimed in claim 14, wherein the locking members include locking strips extending peripherally about the basket frame in the gaps between adjacent screening element rows, the locking strips engaging juxtaposed r f7 -16- edge regions of the screening elements so as to urge those edge regions into mounting engagement with the basket frame.

16. A screening basket as claimed in claim 15, wherein the locking strips and edge regions of the screening elements are configured to releasably interengage with one another, and the locking strips bridge between the edge regions so as to close the gaps between adjacent screening element rows.

17. A screening basket for a centrifuge ore screening apparatus, substantially as hereinbefore described with reference to what is shown in the accompanying drawings. DATED:

18 December 1995 PHILLIPS ORMONDE FITZPATRICK Attorneys for: LETTELA PTY. LTD. *o ol o go c *e 6 I ABSTRACT A screening basket for a centrifuge screening apparatus. The basket includes a generally frusto-conical shaped basket frame; and, an array of screening elements (12) removably mounted on the frame The screening elements (12) provide a peripheral screening wall (13) within the frame through which ores can be screened. o e*o